IRRADIATION-CAPSULE STUDY OF URANIUM MONOCARBIDE

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

Price, R.B.; Stahl, D.; Stang, J.H.

1960-03-01

Small cylindrical specimens of enriched UC were irradiated to evaluate usefulness as a high-temperature fuel for stationary power reactors. Detailed thermal and nuclear analyses were made to arrive at an appropriate capsule design on the basis of target specimen center-line temperature ( approximately 1500 deg F), specimen surface temperature (1100 deg F), specimen composition (U--5 wt.% C), and acapsule o.d. of 1.125 in. Temperature data from thermocouples inside the capsule indicated that five of the six capsules irradiated operated at close to the design conditions. Irradiation periods for individual capsules were varied to give burnups ranging from 1,000 to 20,000more » Mwd/t of U. Preliminary evidence indicates that this range of burnups was achieved. By using temperature and heat-flux data from the actual irradiations to estimate effective in-pile specimen thermal conductivities, it was found that the conductivity did not appear to vary during the exposures. (auth)« less

Design of a bituminous mixture for perpetual pavement

NASA Astrophysics Data System (ADS)

Gireesh Kumar, S.; Satya, J.; Mittal, Kratagya; Raju, Sridhar

2018-03-01

The flexible pavements with a design period of 50 years without requiring major structural rehabilitation and reconstructions are called as perpetual pavements. The present study aims at designing a high modulus Dense Bituminous Macadam (DBM) mixture for perpetual pavements using Industrial Grade (IG) bitumen in combination with Viscosity Grade (VG30) bitumen. Various blending combinations were tried and the ratio of 70:30 for IG: VG30 was found to fulfill the requirements. The modified Marshall hammer was used for the preparation of specimens, as the nominal size of aggregate was 25 mm. A comparative study on DBM mixture with VG30 alone and with IG: VG30 (70:30) was done and the Optimum Binder Contents obtained were 5.0 % and 5.3 % respectively at 4 % air voids. The water sensitivity tests were carried out on the bituminous specimens in accordance with AASHTO T 283 and the Indirect Tensile Strength (ITS) ratio obtained were 80.0 % and 98.3 % respectively for specimens with VG30 and IG: VG30. The stiffness modulus of DBM specimens with IG: VG30 bitumen was 3 times higher than DBM with VG30 bitumen.

A new specimen management system using RFID technology.

PubMed

Shim, Hun; Uh, Young; Lee, Seung Hwan; Yoon, Young Ro

2011-12-01

The specimen management system with barcode needs to be improved in order to solve inherent problems in work performance. This study describes the application of Radio Frequency Identification (RFID) which is the solution for the problems associated with specimen labeling and management. A new specimen management system and architecture with RFID technology for clinical laboratory was designed. The suggested system was tested in various conditions such as durability to temperature and aspect of effective utilization of new work flow under a virtual hospital clinical laboratory environment. This system demonstrates its potential application in clinical laboratories for improving work flow and specimen management. The suggested specimen management system with RFID technology has advantages in comparison to the traditional specimen management system with barcode in the aspect of mass specimen processing, robust durability of temperature, humidity changes, and effective specimen tracking.

Experimental investigation of reinforced bonded joints for composite laminates.

PubMed

Bisagni, Chiara; Furfari, Domenico; Pacchione, Marco

2018-02-01

An experimental study has been carried out to investigate the behaviour of co-bonded carbon fibre reinforced plastics joints with a novel design incorporating a through the thickness local reinforcement. Different specimens were manufactured to investigate static and fatigue behaviour, as well as delamination size after impact and damage tolerance characteristics. The mechanical performances of the specimens with local reinforcement, consisting of the insertion of spiked thin metal sheets between co-bonded laminates, were compared with those ones obtained from specimens with purely co-bonded joints. This novel design demonstrated by tests that damage progression under cycling load results significantly delayed by the reinforcements. A significant number of experimental results were obtained that can be used to define preliminary design guidelines.

Experimental investigation of reinforced bonded joints for composite laminates

PubMed Central

Bisagni, Chiara; Furfari, Domenico; Pacchione, Marco

2017-01-01

An experimental study has been carried out to investigate the behaviour of co-bonded carbon fibre reinforced plastics joints with a novel design incorporating a through the thickness local reinforcement. Different specimens were manufactured to investigate static and fatigue behaviour, as well as delamination size after impact and damage tolerance characteristics. The mechanical performances of the specimens with local reinforcement, consisting of the insertion of spiked thin metal sheets between co-bonded laminates, were compared with those ones obtained from specimens with purely co-bonded joints. This novel design demonstrated by tests that damage progression under cycling load results significantly delayed by the reinforcements. A significant number of experimental results were obtained that can be used to define preliminary design guidelines. PMID:29568127

Modeling and testing miniature torsion specimens for SiC joining development studies for fusion

DOE PAGES

Henager, Jr., C. H.; Nguyen, Ba N.; Kurtz, Richard J.; ...

2015-08-05

The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. For this research, miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti 3SiC 2 + SiC joints with SiC and tested in torsion-shear prior to and after neutron irradiation. However, many miniature torsion specimens fail out-of-plane within the SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated strengths to determine irradiation effects.more » Finite element elastic damage and elastic–plastic damage models of miniature torsion joints are developed that indicate shear fracture is more likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated test data for a variety of joint materials. The unirradiated data includes Ti 3SiC 2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. Finally, the implications for joint data based on this sample design are discussed.« less

Recommendations for clinical biomarker specimen preservation and stability assessments.

PubMed

Dakappagari, Naveen; Zhang, Hui; Stephen, Laurie; Amaravadi, Lakshmi; Khan, Masood U

2017-04-01

With the wide use of biomarkers to enable critical drug-development decisions, there is a growing concern from scientific community on the need for a 'standardized process' for ensuring biomarker specimen stability and hence, a strong desire to share best practices on preserving the integrity of biomarker specimens in clinical trials and the design of studies to evaluate analyte stability. By leveraging representative industry experience, we have attempted to provide an overview of critical aspects of biomarker specimen stability commonly encountered during clinical development, including: planning of clinical sample collection procedures, clinical site training, selection of sample preservation buffers, shipping logistics, fit-for-purpose stability assessments in the analytical laboratory and presentation of case studies covering widely utilized biomarker specimen types.

Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

PubMed Central

Wokosin, David L.; Squirrell, Jayne M.; Eliceiri, Kevin W.; White, John G.

2008-01-01

Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components. PMID:18607511

Microwave processing of a dental ceramic used in computer-aided design/computer-aided manufacturing.

PubMed

Pendola, Martin; Saha, Subrata

2015-01-01

Because of their favorable mechanical properties and natural esthetics, ceramics are widely used in restorative dentistry. The conventional ceramic sintering process required for their use is usually slow, however, and the equipment has an elevated energy consumption. Sintering processes that use microwaves have several advantages compared to regular sintering: shorter processing times, lower energy consumption, and the capacity for volumetric heating. The objective of this study was to test the mechanical properties of a dental ceramic used in computer-aided design/computer-aided manufacturing (CAD/CAM) after the specimens were processed with microwave hybrid sintering. Density, hardness, and bending strength were measured. When ceramic specimens were sintered with microwaves, the processing times were reduced and protocols were simplified. Hardness was improved almost 20% compared to regular sintering, and flexural strength measurements suggested that specimens were approximately 50% stronger than specimens sintered in a conventional system. Microwave hybrid sintering may preserve or improve the mechanical properties of dental ceramics designed for CAD/CAM processing systems, reducing processing and waiting times.

Optical workstation with concurrent, independent multiphoton imaging and experimental laser microbeam capabilities

NASA Astrophysics Data System (ADS)

Wokosin, David L.; Squirrell, Jayne M.; Eliceiri, Kevin W.; White, John G.

2003-01-01

Experimental laser microbeam techniques have become established tools for studying living specimens. A steerable, focused laser beam may be used for a variety of experimental manipulations such as laser microsurgery, optical trapping, localized photolysis of caged bioactive probes, and patterned photobleaching. Typically, purpose-designed experimental systems have been constructed for each of these applications. In order to assess the consequences of such experimental optical interventions, long-term, microscopic observation of the specimen is often required. Multiphoton excitation, because of its ability to obtain high-contrast images from deep within a specimen with minimal phototoxic effects, is a preferred technique for in vivo imaging. An optical workstation is described that combines the functionality of an experimental optical microbeam apparatus with a sensitive multiphoton imaging system designed for use with living specimens. Design considerations are discussed and examples of ongoing biological applications are presented. The integrated optical workstation concept offers advantages in terms of flexibility and versatility relative to systems implemented with separate imaging and experimental components.

Optimal design of studies of influenza transmission in households. I: case-ascertained studies.

PubMed

Klick, B; Leung, G M; Cowling, B J

2012-01-01

Case-ascertained household transmission studies, in which households including an 'index case' are recruited and followed up, are invaluable to understanding the epidemiology of influenza. We used a simulation approach parameterized with data from household transmission studies to evaluate alternative study designs. We compared studies that relied on self-reported illness in household contacts vs. studies that used home visits to collect swab specimens for virological confirmation of secondary infections, allowing for the trade-off between sample size vs. intensity of follow-up given a fixed budget. For studies estimating the secondary attack proportion, 2-3 follow-up visits with specimens collected from all members regardless of illness were optimal. However, for studies comparing secondary attack proportions between two or more groups, such as controlled intervention studies, designs with reactive home visits following illness reports in contacts were most powerful, while a design with one home visit optimally timed also performed well.

Effect of storage temperature on endogenous GHB levels in urine.

PubMed

LeBeau, M A; Miller, M L; Levine, B

2001-06-15

Because gamma-hydroxybutyrate (GHB) is an endogenous substance present in the body and is rapidly eliminated after ingestion, toxicologists investigating drug-facilitated sexual assault cases are often asked to differentiate between endogenous and exogenous levels of GHB in urine samples. This study was designed to determine the effects of storage temperature on endogenous GHB levels in urine. Specifically, it was designed to ascertain whether endogenous levels can be elevated to a range considered indicative of GHB ingestion. Urine specimens from two subjects that had not been administered exogenous GHB were collected during a 24h period and individually pooled. The pooled specimens were separated into standard sample cups and divided into three storage groups: room temperature ( approximately 25 degrees C), refrigerated (5 degrees C), and frozen (-10 degrees C). Additionally, some specimens were put through numerous freeze/thaw cycles to mimic situations that may occur if multiple laboratories analyze the same specimen. Periodic analysis of the samples revealed increases in the levels of endogenous GHB over a 6-month period. The greatest increase (up to 404%) was observed in the samples maintained at room temperature. The refrigerated specimens showed increases of 140-208%, while the frozen specimens showed smaller changes (88-116%). The specimens subjected to multiple freeze/thaw cycles mirrored specimens that had been thawed only once. None of the stored urine specimens demonstrated increases in GHB concentrations that would be consistent with exogenous GHB ingestion.

Rapid repair of severely earthquake-damaged bridge piers with flexural-shear failure mode

NASA Astrophysics Data System (ADS)

Sun, Zhiguo; Wang, Dongsheng; Du, Xiuli; Si, Bingjun

2011-12-01

An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers (CFRP). After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is provided.

Effectiveness of Specimen Collection Technology in the Reduction of Collection Turnaround Time and Mislabeled Specimens in Emergency, Medical-Surgical, Critical Care, and Maternal Child Health Departments.

PubMed

Saathoff, April M; MacDonald, Ryan; Krenzischek, Erundina

2018-03-01

The objective of this study was to evaluate the impact of specimen collection technology implementation featuring computerized provider order entry, positive patient identification, bedside specimen label printing, and barcode scanning on the reduction of mislabeled specimens and collection turnaround times in the emergency, medical-surgical, critical care, and maternal child health departments at a community teaching hospital. A quantitative analysis of a nonrandomized, pre-post intervention study design evaluated the statistical significance of reduction of mislabeled specimen percentages and collection turnaround times affected by the implementation of specimen collection technology. Mislabeled specimen percentages in all areas decreased from an average of 0.020% preimplementation to an average of 0.003% postimplementation, with a P < .001. Collection turnaround times longer than 60 minutes decreased after the implementation of specimen collection technology by an average of 27%, with a P < .001. Specimen collection and identification errors are a significant problem in healthcare, contributing to incorrect diagnoses, delayed care, lack of essential treatments, and patient injury or death. Collection errors can also contribute to an increased length of stay, increased healthcare costs, and decreased patient satisfaction. Specimen collection technology has structures in place to prevent collection errors and improve the overall efficiency of the specimen collection process.

An experimental and analytical investigation on the response of GR/EP composite I-frames

NASA Technical Reports Server (NTRS)

Moas, E., Jr.; Boitnott, R. L.; Griffin, O. H., Jr.

1991-01-01

Six-foot diameter, semicircular graphite/epoxy specimens representative of generic aircraft frames were loaded quasi-statically to determine their load response and failure mechanisms for large deflections that occur in an airplane crash. These frame-skin specimens consisted of a cylindrical skin section cocured with a semicircular I-frame. Various frame laminate stacking sequences and geometries were evaluated by statically loading the specimen until multiple failures occurred. Two analytical methods were compared for modeling the frame-skin specimens: a two-dimensional branched-shell finite element analysis and a one-dimensional, closed-form, curved beam solution derived using an energy method. Excellent correlation was obtained between experimental results and the finite element predictions of the linear response of the frames prior to the initial failure. The beam solution was used for rapid parameter and design studies, and was found to be stiff in comparison with the finite element analysis. The specimens were found to be useful for evaluating composite frame designs.

Optimization of Elastically Tailored Tow-Placed Plates with Holes

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.; Tatting, Brian F.; Guerdal, Zafer

2003-01-01

Elastic stiffness tailoring of laminated composite panels by allowing the fibers to curve within the plane of the laminate is a design concept that has been demonstrated to be both beneficial and practical. The objective of the present paper is to demonstrate the effectiveness of stiffness tailoring through the use of curvilinear fibers to reduce stress concentrations around the hole and improve the load carrying capability of panels. Preliminary panel designs that are to be manufactured and tested were determined through design studies for flat plates without holes under axial compression using an optimization program. These candidate designs were then analyzed with finite element models that accurately reflect the test conditions and geometries in order to decide upon the final designs for manufacture and testing. An advanced tow-placement machine is used to manufacture the test panels with varying fiber orientation angles. A total of six large panels measuring three feet by six feet, each of which is used to produce four specimens with or without holes, are fabricated. The panels were machined into specimens with holes and tested at NASA Langley Research Center. Buckling response and failure of panels without holes and with two different hole dimensions are presented. Buckling and failure loads of tow-steered specimens are significantly greater than the buckling and failure loads of traditional straight-fiber specimens.

Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading

NASA Astrophysics Data System (ADS)

Ketiyot, Rattapon; Hansapinyo, Chayanon

2018-04-01

An experimental investigation was conducted to study the performance of precast beam-column concrete connections using T-section steel inserts into the concrete beam and joint core, under reversed cyclic loading. Six 2/3-scale interior beam-column subassemblies, one monolithic concrete specimen and five precast concrete specimens were tested. One precast specimen was a simple connection for a gravity load resistant design. Other precast specimens were developed with different attributes to improve their seismic performance. The test results showed that the performance of the monolithic specimen M1 represented ductile seismic behavior. Failure of columns and joints could be prevented, and the failure of the frame occurred at the flexural plastic hinge formation at the beam ends, close to the column faces. For the precast specimens, the splitting crack along the longitudinal lapped splice was a major failure. The precast P5 specimen with double steel T-section inserts showed better seismic performance compared to the other precast models. However, the dowel bars connected to the steel inserts were too short to develop a bond. The design of the precast concrete beams with lap splice is needed for longer lap lengths and should be done at the beam mid span or at the low flexural stress region.

Charpy Impact Energy and Microindentation Hardness of 60-NITINOL

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2012-01-01

60-NITINOL (60 wt.% Ni 40 wt.% Ti) is being studied as a material for advanced aerospace components. The Charpy impact energy and microindentation hardness has been studied for this material, fabricated by vacuum induction skull melting (casting) and by hot isostatic pressing. Test specimens were prepared in various hardened and annealed heat treatment conditions. The average impact energy ranged from 0.33 to 0.49J for the hardened specimens while the annealed specimens had impact energies ranging from 0.89 to 1.18J. The average hardness values of the hardened specimens ranged from 590 to 676 HV while that of the annealed specimens ranged from 298 to 366 HV, suggesting an inverse relationship between impact energy and hardness. These results are expected to provide guidance in the selection of heat treatment processes for the design of mechanical components.

Conceptual design of a biological specimen holding facility. [Life Science Laboratory for Space Shuttle

NASA Technical Reports Server (NTRS)

Jackson, J. K.; Yakut, M. M.

1976-01-01

An all-important first step in the development of the Spacelab Life Science Laboratory is the design of the Biological Specimen Holding Facility (BSHF) which will provide accommodation for living specimens for life science research in orbit. As a useful tool in the understanding of physiological and biomedical changes produced in the weightless environment, the BSHF will enable biomedical researchers to conduct in-orbit investigations utilizing techniques that may be impossible to perform on human subjects. The results of a comprehensive study for defining the BSHF, description of its experiment support capabilities, and the planning required for its development are presented. Conceptual designs of the facility, its subsystems and interfaces with the Orbiter and Spacelab are included. Environmental control, life support and data management systems are provided. Interface and support equipment required for specimen transfer, surgical research, and food, water and waste storage is defined. New and optimized concepts are presented for waste collection, feces and urine separation and sampling, environmental control, feeding and watering, lighting, data management and other support subsystems.

i RadMat: A thermo-mechanical testing system for in situ high-energy X-ray characterization of radioactive specimens

DOE PAGES

Zhang, Xuan; Xu, Chi; Wang, Leyun; ...

2017-01-27

Here, we present an in situ Radiated Materials (iRadMat) experimental module designed to interface with a servo-hydraulic load frame for X-ray measurements at beamline 1-ID at the Advanced Photon Source. This new capability allows in situ studies of radioactive specimens subject to thermo-mechanical loading using a suite of high-energy X-ray scattering and imaging techniques. The iRadMat is a radiation-shielded vacuum heating system with the sample rotation-under-load capability. We describe the design features and performances of the iRadMat and present a dataset from a 300 °C uniaxial tensile test of a neutron-irradiated pure Fe specimen to demonstrate its capabilities.

Investigation of the Leak Response of a Carbon-Fiber Laminate Loaded in Biaxial Tension

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Ratcliffe, James G.

2013-01-01

Designers of pressurized structures have been reluctant to use composite materials because of concerns over leakage. Biaxial stress states are expected to be the worst-case loading condition for allowing leakage to occur through microcracks. To investigate the leakage behavior under in-plane biaxial loading, a cruciform composite specimen was designed that would have a relatively large test section with a uniform 1:1 biaxial loading ratio. A 7.6-cm-square test section was desired for future investigations of the leakage response as a result of impact damage. Many iterations of the cruciform specimen were evaluated using finite element analysis to reduce stress concentrations and maximize the size of the uniform biaxial strain field. The final design allowed the specimen to go to relatively high biaxial strain levels without incurring damage away from the test section. The specimen was designed and manufactured using carbon/epoxy fabric with a four-ply-thick, quasi-isotropic, central test section. Initial validation and testing were performed on a specimen without impact damage. The specimen was tested to maximum biaxial strains of approximately 4500micro epsilon without apparent damage. A leak measurement system containing a pressurized cavity was clamped to the test section and used to measure the flow rate through the specimen. The leakage behavior of the specimen was investigated for pressure differences up to 172 kPa

An ultrahigh vacuum multipurpose specimen chamber with sample introduction system for in situ transmission electron microscopy investigations

NASA Technical Reports Server (NTRS)

Heinemann, K.; Poppa, H.

1986-01-01

A commercial transmission electron microscope (TEM), with flat-plate upper pole piece configuration of the objective lens, and top-entry specimen introduction was modified by introducing an ultrahigh vacuum (UHV) specimen chamber for in situ TEM experimentation. The pumping and design principles and special features of this UHV chamber, which makes it possible to obtain 5 x 10 to the -10th mbar pressure at the site of the specimen, while maintaining the airlock system that allows operation in the 10 to the -10th mbar range within 15 min after specimen change, are described. Design operating pressures and image quality (resolution of metal particles smaller than 1 nm in size) were achieved. Schematic drawings and design dimensions are included.

Umbilical Connect Techniques Improvement-Technology Study

NASA Technical Reports Server (NTRS)

Valkema, Donald C.

1972-01-01

The objective of this study was to develop concepts, specifications, designs, techniques, and procedures capable of significantly reducing the time required to connect and verify umbilicals for ground services to the space shuttle. The desired goal was to reduce the current time requirement of several shifts for the Saturn 5/Apollo to an elapsed time of less than one hour to connect and verify all of the space shuttle ground service umbilicals. The study was conducted in four phases: (1) literature and hardware examination, (2) concept development, (3) concept evaluation and tradeoff analysis, and (4) selected concept design. The final product of this study was a detail design of a rise-off disconnect panel prototype test specimen for a LO2/LH2 booster (or an external oxygen/hydrogen tank for an orbiter), a detail design of a swing-arm mounted preflight umbilical carrier prototype test specimen, and a part 1 specification for the umbilical connect and verification design for the vehicles as defined in the space shuttle program.

Study of the fracture kinetics in structural aluminum alloys subjected to a long-term action of a static load and a corrosive medium using specimens of a new type

NASA Astrophysics Data System (ADS)

Kablov, E. N.; Grinevich, A. V.; Lutsenko, A. N.; Erasov, V. S.; Nuzhnyi, G. A.; Gulina, I. V.

2017-04-01

A new type of specimens is proposed to study the fracture kinetics of the metallic materials subjected to a long-term simultaneous action of a tensile load and a corrosive medium. The new design of specimens makes it possible to determine the stress intensity factor at the crack opening fixed by a wedging bolt, to perform investigations in any aggressive medium, and to measure the tensile load on a specimen at any stage of tests. Standard apparatus is used for this purpose. Plate specimens made of structural aluminum alloys 1163T and V95pchT2 are tested. A paradoxical fact of increasing the conventional stress intensity factor of the V95pchT2 alloy during the development of a corrosion crack is revealed.

Transition Fracture Toughness Characterization of Eurofer 97 Steel using Pre-Cracked Miniature Multi-notch Bend Bar Specimens

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

Chen, Xiang; Sokolov, Mikhail A.; Linton, Kory D.

In this report, we present the feasibility study of using pre-cracked miniature multi-notch bend bar specimens (M4CVN) with a dimension of 45mm (length) x 3.3mm (width) x 1.65mm (thickness) to characterize the transition fracture toughness of Eurofer97 based on the ASTM E1921 Master Curve method. From literature survey results, we did not find any obvious specimen size effects on the measured fracture toughness of unirradiated Eurofer97. Nonetheless, in order to exclude the specimen size effect on the measured fracture toughness of neutron irradiated Eurofer97, comparison of results obtained from larger size specimens with those from smaller size specimens after neutronmore » irradiation is necessary, which is not practical and can be formidably expensive. However, limited literature results indicate that the transition fracture toughness of Eurofer97 obtained from different specimen sizes and geometries followed the similar irradiation embrittlement trend. We then described the newly designed experimental setup to be used for testing neutron irradiated Eurofer97 pre-cracked M4CVN bend bars in the hot cell. We recently used the same setup for testing neutron irradiated F82H pre-cracked miniature multi-notch bend bars with great success. Considering the similarity in materials, specimen types, and the nature of tests between Eurofer97 and F82H, we believe the newly designed experimental setup can be used successfully in fracture toughness testing of Eurofer97 pre-cracked M4CVN specimens.« less

Characterization of the Edge Crack Torsion (ECT) Test for Mode III Fracture Toughness Measurement of Laminated Composites

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.

2004-01-01

The edge crack torsion (ECT) test is designed to initiate mode III delamination growth in composite laminates. The test has undergone several design changes during its development. The objective of this paper was to determine the suitability of the current ECT test design a mode III fracture test. To this end, ECT tests were conducted on specimens manufactured from IM7/8552 and S2/8552 tape laminates. Three-dimensional finite element analyses were performed. The analysis results were used to calculate the distribution of mode I, mode II, and mode III strain energy release rate along the delamination front. The results indicated that mode IIIdominated delamination growth would be initiated from the specimen center. However, in specimens of both material types, the measured values of GIIIc exhibited significant dependence on delamination length. Load-displacement response of the specimens exhibited significant deviation from linearity before specimen failure. X-radiographs of a sample of specimens revealed that damage was initiated in the specimens prior to failure. Further inspection of the failure surfaces is required to identify the damage and determine that mode III delamination is initiated in the specimens.

Characterization of the Edge Crack Torsion (ECT) Test for Mode III Fracture Toughness Measurement of Laminated Composites

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.

2004-01-01

The edge crack torsion (ECT) test is designed to initiate mode III delamination growth in composite laminates. An ECT specimen is a rectangular laminate, containing an edge delamination at the laminate mid-plane. Torsion load is applied to the specimens, resulting in relative transverse shear sliding of the delaminated faces. The test data reduction schemes are intended to yield initiation values of critical mode III strain energy release rate, G(sub IIIc), that are constant with delamination length. The test has undergone several design changes during its development. The objective of this paper was to determine the suitability of the current ECT test design as a mode III fracture test. To this end, ECT tests were conducted on specimens manufactured from IM7/8552 and specimens made from S2/8552 tape laminates. Several specimens, each with different delamination lengths are tested. Detailed, three-dimensional finite element analyses of the specimens were performed. The analysis results were used to calculate the distribution of mode I, mode II, and mode III strain energy release rate along the delamination front. The results indicated that mode III-dominated delamination growth would be initiated from the specimen center. However, in specimens of both material types, the measured values of G(sub IIIc) exhibited significant dependence on delamination length. Furthermore, there was a large amount of scatter in the data. Load-displacement response of the specimens exhibited significant deviation from linearity before specimen failure. X-radiographs of a sample of specimens revealed that damage was initiated in the specimens prior to failure. Further inspection of the failure surfaces is required to identify the damage and determine that mode III delamination is initiated in the specimens.

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

Henager, Jr., C. H.; Nguyen, Ba N.; Kurtz, Richard J.

The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. For this research, miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti 3SiC 2 + SiC joints with SiC and tested in torsion-shear prior to and after neutron irradiation. However, many miniature torsion specimens fail out-of-plane within the SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated strengths to determine irradiation effects.more » Finite element elastic damage and elastic–plastic damage models of miniature torsion joints are developed that indicate shear fracture is more likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated test data for a variety of joint materials. The unirradiated data includes Ti 3SiC 2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. Finally, the implications for joint data based on this sample design are discussed.« less

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

Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

The international fusion community has designed a miniature torsion specimen for neutron irradiation studies of joined SiC and SiC/SiC composite materials. Miniature torsion joints based on this specimen design were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with CVD-SiC and tested in torsion-shear prior to and after neutron irradiation. However, many of these miniature torsion specimens fail out-of-plane within the CVD-SiC specimen body, which makes it problematic to assign a shear strength value to the joints and makes it difficult to compare unirradiated and irradiated joint strengths to determine the effects of themore » irradiation. Finite element elastic damage and elastic-plastic damage models of miniature torsion joints are developed that indicate shear fracture is likely to occur within the body of the joined sample and cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The model results are compared and discussed with regard to unirradiated and irradiated joint test data for a variety of joint materials. The unirradiated data includes Ti3SiC2 + SiC/CVD-SiC joints with tailored joint moduli, and includes steel/epoxy and CVD-SiC/epoxy joints. The implications for joint data based on this sample design are discussed.« less

The effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resin: An in vitro study.

PubMed

Anasane, Nayana; Ahirrao, Yogesh; Chitnis, Deepa; Meshram, Suresh

2013-03-01

Denture fracture is an unresolved problem in complete denture prosthodontics. However, the repaired denture often experiences a refracture at the repaired site due to poor transverse strength. Hence, this study was conducted to evaluate the effect of joint surface contours and glass fiber reinforcement on the transverse strength of repaired acrylic resins. A total of 135 specimens of heat polymerized polymethyl methacrylate resin of dimensions 64 × 10 × 2.5 mm were fabricated. Fifteen intact specimens served as the control and 120 test specimens were divided into four groups (30 specimens each), depending upon the joint surface contour (butt, bevel, rabbet and round), with two subgroups based on type of the repair. Half of the specimens were repaired with plain repair resin and the other half with glass fibers reinforced repair resin. Transverse strength of the specimens was determined using three-point bending test. The results were analyzed using one-way ANOVA and Tukey post-hoc test (α= 0.05). Transverse strength values for all repaired groups were significantly lower than those for the control group (P < 0.001) (88.77 MPa), with exception of round surface design repaired with glass fiber reinforced repair resin (89.92 MPa) which was significantly superior to the other joint surface contours (P < 0.001). Glass fiber reinforced resin significantly improved the repaired denture base resins as compared to the plain repair resin (P < 0.001). Specimens repaired with glass fiber reinforced resin and round surface design exhibited highest transverse strength; hence, it can be advocated for repair of denture base resins.

Commercial products to preserve specimens for tuberculosis diagnosis: a systematic review.

PubMed

Reeve, B W P; McFall, S M; Song, R; Warren, R; Steingart, K R; Theron, G

2018-07-01

Eliminating tuberculosis in high-burden settings requires improved diagnostic capacity. Important tests such as Xpert® MTB/RIF and culture are often performed at centralised laboratories that are geographically distant from the point of specimen collection. Preserving specimen integrity during transportation, which could affect test performance, is challenging. To conduct a systematic review of commercial products for specimen preservation for a World Health Organization technical consultation. Databases were searched up to January 2018. Methodological quality was assessed using Quality Assessment of Technical Studies, a new technical study quality-appraisal tool, and Quality Assessment of Diagnostic Accuracy Studies-2. Studies were analysed descriptively in terms of the different products, study designs and diagnostic strategies used. Four products were identified from 16 studies: PrimeStore-Molecular-Transport-Medium (PS-MTM), FTA card, GENO•CARD (all for nucleic acid amplification tests [NAATs]) and OMNIgene•SPUTUM (OMS; culture, NAATs). PS-MTM, but not FTA card or GENO•CARD, rendered Mycobacterium tuberculosis non-culturable. OMS reduced Löwenstein-Jensen but not MGIT™ 960™ contamination, led to delayed MGIT time-to-positivity, resulted in Xpert performance similar to cold chain-transported untreated specimens, and obviated the need for N-acetyl-L-cysteine-sodium hydroxide decontamination. Data from paucibacillary specimens were limited. Evidence that a cold chain improves culture was mixed and absent for Xpert. The effect of the product alone could be discerned in only four studies. Limited evidence suggests that transport products result in test performance comparable to that seen in cold chain-transported specimens.

Evaluation of the Kodak Surecell Chlamydia test for the laboratory diagnosis of adult inclusion conjunctivitis.

PubMed

Tantisira, J G; Kowalski, R P; Gordon, Y J

1995-07-01

The Kodak Surecell Chlamydia test, a rapid enzyme immunoassay, has been reported to be highly sensitive (93%) and specific (96%) for detecting chlamydial lipopolysaccharide antigen in conjunctival specimens from infants, but has not been evaluated previously in adult conjunctival specimens. This study was designed to determine the efficacy of the Kodak Surecell Chlamydia test for the laboratory diagnosis of adult inclusion conjunctivitis. Twenty Chlamydia culture-positive conjunctival specimens from adults (true-positives) and 20 true-negative specimens were tested with the Kodak Surecell Chlamydia test. The Kodak Surecell Chlamydia test was 40% (8/20) sensitive, 100% (20/20) specific, and 70% (28/40) efficient. This study indicates that the Kodak Surecell Chlamydia test, though highly specific, is less sensitive in its ability to diagnose chlamydial conjunctivitis in adults than has been reported previously in infants.

New specimen design for studying the growth of small fatigue cracks with surface acoustic waves

NASA Astrophysics Data System (ADS)

London, Blair

1985-08-01

The study of small surface fatigue cracks in AISI 4140 quenched and tempered steel by a nondestructive surface acoustic wave technique is summarized. A novel cantilevered bending, plate-type fatigue specimen is described that is compatible with the acoustic method. Small cracks are initiated from a 25-μm deep surface pit produced by an electrospark machine. The importance of studying these cracks which closely approximate naturally occurring fatigue cracks is briefly discussed.

Design and fabrication of composite wing panels containing a production splice

NASA Technical Reports Server (NTRS)

Reed, D. L.

1975-01-01

Bolted specimens representative of both upper and lower wing surface splices of a transport aircraft were designed and manufactured for static and random load tension and compression fatigue testing including ground-air-ground load reversals. The specimens were fabricated with graphite-epoxy composite material. Multiple tests were conducted at various load levels and the results were used as input to a statistical wearout model. The statically designed specimens performed very well under highly magnified fatigue loadings. Two large panels, one tension and compression, were fabricated for testing by NASA-LRC.

Pure moment testing for spinal biomechanics applications: Fixed versus sliding ring cable-driven test designs.

PubMed

Eguizabal, Johnny; Tufaga, Michael; Scheer, Justin K; Ames, Christopher; Lotz, Jeffrey C; Buckley, Jenni M

2010-05-07

In vitro multi-axial bending testing using pure moment loading conditions has become the standard in evaluating the effects of different types of surgical intervention on spinal kinematics. Simple, cable-driven experimental set-ups have been widely adopted because they require little infrastructure. Traditionally, "fixed ring" cable-driven experimental designs have been used; however, there have been concerns with the validity of this set-up in applying pure moment loading. This study involved directly comparing the loading state induced by a traditional "fixed ring" apparatus versus a novel "sliding ring" approach. Flexion-extension bending was performed on an artificial spine model and a single cadaveric test specimen, and the applied loading conditions to the specimen were measured with an in-line multiaxial load cell. The results showed that the fixed ring system applies flexion-extension moments that are 50-60% less than the intended values. This design also imposes non-trivial anterior-posterior shear forces, and non-uniform loading conditions were induced along the length of the specimen. The results of this study indicate that fixed ring systems have the potential to deviate from a pure moment loading state and that our novel sliding ring modification corrects this error in the original test design. This suggests that the proposed sliding ring design should be used for future in vitro spine biomechanics studies involving a cable-driven pure moment apparatus. Copyright 2010 Elsevier Ltd. All rights reserved.

A Damage Tolerance Comparison of Composite Hat-Stiffened and Honeycomb Sandwich Structure for Launch Vehicle Interstage Applications

NASA Technical Reports Server (NTRS)

Nettles, A. T.

2011-01-01

In this study, a direct comparison of the compression-after-impact (CAI) strength of impact-damaged, hat-stiffened and honeycomb sandwich structure for launch vehicle use was made. The specimens used consisted of small substructure designed to carry a line load of approx..3,000 lb/in. Damage was inflicted upon the specimens via drop weight impact. Infrared thermography was used to examine the extent of planar damage in the specimens. The specimens were prepared for compression testing to obtain residual compression strength versus damage severity curves. Results show that when weight of the structure is factored in, both types of structure had about the same CAI strength for a given damage level. The main difference was that the hat-stiffened specimens exhibited a multiphase failure whereas the honeycomb sandwich structure failed catastrophically.

Flexural strength and failure modes of layered ceramic structures.

PubMed

Borba, Márcia; de Araújo, Maico D; de Lima, Erick; Yoshimura, Humberto N; Cesar, Paulo F; Griggs, Jason A; Della Bona, Alvaro

2011-12-01

To evaluate the effect of the specimen design on the flexural strength (σ(f)) and failure mode of ceramic structures, testing the hypothesis that the ceramic material under tension controls the mechanical performance of the structure. Three ceramics used as framework materials for fixed partial dentures (YZ--Vita In-Ceram YZ; IZ--Vita In-Ceram Zirconia; AL--Vita In-Ceram AL) and two veneering porcelains (VM7 and VM9) were studied. Bar-shaped specimens were produced in three different designs (n=10): monolithic, two layers (porcelain-framework) and three layers (TRI) (porcelain-framework-porcelain). Specimens were tested for three-point flexural strength at 1MPa/s in 37°C artificial saliva. For bi-layered design, the specimens were tested in both conditions: with porcelain (PT) or framework ceramic (FT) layer under tension. Fracture surfaces were analyzed using stereomicroscope and scanning electron microscopy (SEM). Young's modulus (E) and Poisson's ratio (ν) were determined using ultrasonic pulse-echo method. Results were statistically analyzed by Kruskal-Wallis and Student-Newman-Keuls tests. Except for VM7 and VM9, significant differences were observed for E values among the materials. YZ showed the highest ν value followed by IZ and AL. YZ presented the highest σ(f). There was no statistical difference in the σ(f) value between IZ and IZ-FT and between AL and AL-FT. σ(f) values for YZ-PT, IZ-PT, IZ-TRI, AL-PT, AL-TRI were similar to the results obtained for VM7 and VM9. Two types of fracture mode were identified: total and partial failure. The mechanical performance of the specimens was determined by the material under tension during testing, confirming the study hypothesis. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Identification of Cytological Features Distinguishing Mucosa-Associated Lymphoid Tissue Lymphoma from Reactive Lymphoid Proliferation Using Thyroid Liquid-Based Cytology

PubMed Central

Suzuki, Ayana; Hirokawa, Mitsuyoshi; Ito, Aki; Takada, Nami; Higuchi, Miyoko; Hayashi, Toshitetsu; Kuma, Seiji; Miyauchi, Akira

2018-01-01

Objective To identify cytological differences between mucosa-associated lymphoid tissue lymphoma (MALT-L) and nonneoplastic lymphocytes using thyroid liquid-based cytology (LBC). Study Design We observed LBC and conventional specimens from 35 MALT-L cases, 3 diffuse large B-cell cell lymphoma (DLBCL) cases, and 44 prominent nonneoplastic lymphocytic infiltration cases. Results In MALT-L cases, the incidence of lymphoglandular bodies in the LBC specimens was lower than that in the conventional specimens (p < 0.001). Moreover, the nuclear sizes in LBC specimens were larger than those in conventional specimens. In 62.9% of the MALT-L and all DLBCL specimens, large nuclei were present in > 10% of the lymphoid cells in LBC specimens. Two cases with prominent nonneoplastic lymphocytic infiltration also exhibited these findings. In LBC specimens, swollen naked nuclei with less punctate chromatin patterns and thin nuclear margins were observed in 92.1% of lymphoma and 20.5% of prominent nonneoplastic lymphocytic infiltration. Elongated nuclei were significantly more apparent in thyroid lymphoma than in prominent nonneoplastic lymphocytic infiltration (p < 0.001), with a significantly higher incidence in LBC specimens than in conventional specimens (p < 0.001). Conclusions Lymphoglandular bodies are not reliable markers for lymphoma diagnosis using LBC specimens. Large, swollen naked, and elongated nuclei are useful in distinguishing thyroid lymphoma from nonneoplastic lymphocytes in LBC specimens. PMID:29597203

Assessing the feasibility of yttria-stabilized zirconia in novel designs as mandibular anterior fixed lingual retention following orthodontic treatment

NASA Astrophysics Data System (ADS)

Stout, Matthew

The purpose of this study is to explore the feasibility of yttria-stabilized zirconia (Y-TZP) in fixed lingual retention as an alternative to stainless steel. Exploratory Y-TZP specimens were milled to establish design parameters. Next, specimens were milled according to ASTM standard C1161-13 and subjected to four-point flexural test to determine materials properties. Finite Element (FE) Analysis was employed to evaluate nine novel cross-sectional designs and compared to stainless steel wire. Each design was analyzed under the loading conditions to determine von Mises and bond stress. The most promising design was fabricated to assess accuracy and precision of current CAD/CAM milling technology. The superior design had a 1.0 x 0.5 mm semi-elliptical cross section and was shown to be fabricated reliably. Overall, the milling indicated a maximum percent standard deviation of 9.3 and maximum percent error of 13.5 with a cost of $30 per specimen. Y-TZP can be reliably milled to dimensions comparable to currently available metallic retainer wires. Further research is necessary to determine the success of bonding protocol and clinical longevity of Y-TZP fixed retainers. Advanced technology is necessary to connect the intraoral scan to an aesthetic and patient-specific Y-TZP fixed retainer.

The length of pre-existing fissures effects on the mechanical properties of cracked red sandstone and strength design in engineering.

PubMed

Wu, Jiangyu; Feng, Meimei; Yu, Bangyong; Han, Guansheng

2018-01-01

It is important to study the mechanical properties of cracked rock to understand the engineering behavior of cracked rock mass. Consequently, the influence of the length of pre-existing fissures on the strength, deformation, acoustic emission (AE) and failure characteristics of cracked rock specimen was analyzed, and the optimal selection of strength parameter in engineering design was discussed. The results show that the strength parameters (stress of dilatancy onset and uniaxial compressive strength) and deformation parameters (axial strain and circumferential strain at dilatancy onset and peak point) of cracked rock specimen decrease with the increase of the number of pre-existing fissures, and the relations which can use the negative exponential function to fit. Compared with the intact rock specimens, the different degrees of stress drop phenomena were produced in the process of cracked rock specimens when the stress exceeds the dilatancy onset. At this moment, the cracked rock specimens with the existence of stress drop are not instantaneous failure, but the circumferential strain, volumetric strain and AE signals increase burstingly. And the yield platform was presented in the cracked rock specimen with the length of pre-existing fissure more than 23mm, the yield failure was gradually conducted around the inner tip of pre-existing fissure, the development of original fissures and new cracks was evolved fully in rock. However, the time of dilatancy onset is always ahead of the the time of that point with the existence of stress drop. It indicates that the stress of dilatancy onset can be as the parameter of strength design in rock engineering, which can effectively prevent the large deformation of rock. Copyright © 2017 Elsevier B.V. All rights reserved.

Identification of type materials of the species of Protypotherium Ameghino, 1885 and Patriarchus Ameghino, 1889 (Notoungulata: Interatheriidae) erected by Florentino Ameghino.

PubMed

FernÁndez, Mercedes; Fernicola, Juan Carlos; CerdeÑo, Esperanza; Reguero, Marcelo A

2018-02-27

The first collections of Interatheriinae (Interatheriidae, Notoungulata) were created by the brothers Florentino and Carlos Ameghino, based on fossil specimens collected from diverse outcrops of Argentina and housed at different national institutions. In order to perform a systematic study of the subfamily, it is essential to revise as much specimens as possible, but first of all those that were used to establish the respective species, that is, the type material. Florentino Ameghino never referred to the collection number of the type specimens of the species he erected in any of his publications; this fact added to the occasional absence of illustrations and adequate descriptions, all of which make their identification a complex task. Thus, when studying the species erected by Florentino Ameghino within Protypotherium and Patriarchus, we recognised a lack of correspondence between some specimens that appeared labelled as types in the collections and the original descriptions of these species. In this contribution, we identify the type specimens of the eleven species of Protypotherium and eight of Patriarchus founded by Florentino Ameghino, housed in the Museo Argentino de Ciencias Naturales "Bernardino Rivadavia" (Buenos Aires, Argentina) and the Zoological Museum of the University of Copenhagen (Denmark). Three case studies are presented: a) specimens correctly identified; b) specimens erroneously catalogued as type material; and c) specimens not established as types in Ameghino's catalogue, but herein recognised as such. Lectotype and paralectotype of P. antiquum are herein designated.

Molecular Typing of Clinical Adenovirus Specimens by an Algorithm which Permits Detection of Adenovirus Coinfections and Intermediate Adenovirus Strains

PubMed Central

McCarthy, Troy; Lebeck, Mark G.; Capuano, Ana W.; Schnurr, David P.; Gray, Gregory C.

2009-01-01

Background Epidemiological data suggest that clinical outcomes of human adenovirus (HAdV) infection may be influenced by virus serotype, coinfection with multiple strains, or infection with novel intermediate strains. In this report, we propose a clinical algorithm for detecting HAdV coinfection and intermediate strains. Study Design We PCR amplified and sequenced subregions of the hexon and fiber genes of 342 HAdV positive clinical specimens obtained from 14 surveillance laboratories. Sequences were then compared with those from 52 HAdV prototypic strains. HAdV positive specimens that showed nucleotide sequence identity with a corresponding prototype strain were designated as being of that strain. When hexon and fiber gene sequences disagreed, or sequence identity was low, the specimens were further characterized by viral culture, plaque purification, repeat PCR with sequencing, and genome restriction enzyme digest analysis. Results Of the 342 HAdV-positive clinical specimens, 328 (95.9%) were single HAdV strain infections, 12 (3.5%) were coinfections, and 2 (0.6%) had intermediate strains. Coinfected specimens and intermediate HAdV strains considered together were more likely to be associated with severe illness compared to other HAdv-positive specimens (OR=3.8; 95% CI = 1.2–11.9). Conclusions The majority of severe cases of HAdV illness cases occurred among immunocompromised patients. The analytic algorithm we describe here can be used to screen clinical specimens for evidence of HAdV coinfection and novel intermediate HAdV strains. This algorithm may be especially useful in investigating HAdV outbreaks and clusters of unusually severe HAdV disease. PMID:19577957

Effect of fiber orientation on the failure behavior of a glass-fiber reinforced thermoplastic composite

NASA Astrophysics Data System (ADS)

Liang, Jiaai; Kalyanasundaram, Shankar

2017-05-01

In this study, hour-glass specimens made of a glass-fiber reinforced polypropylene composite with different fiber orientations were stamp formed in an open die. Strains on the surfaces of these specimens were recorded by a 3D photogrammetric measurement system. Specimens were cut into the designed shapes with two different fiber orientations [0°/90° and 45°/45°]. Based on the forming limit diagrams drawn for these material systems, it is found that change in fiber orientation induces change in deformation mode and different forming limit in strains.

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.

Molecular Auditing: An Evaluation of Unsuspected Tissue Specimen Misidentification.

PubMed

Demetrick, Douglas J

2018-06-18

Context Specimen misidentification is the most significant error in laboratory medicine, potentially accounting for hundreds of millions of dollars in extra health care expenses and significant morbidity in patient populations in the United States alone. New technology allows the unequivocal documentation of specimen misidentification or contamination; however, the value of this technology currently depends on suspicion of the specimen integrity by a pathologist or other health care worker. Objective To test the hypothesis that there is a detectable incidence of unsuspected tissue specimen misidentification among cases submitted for routine surgical pathology examination. Design To test this hypothesis, we selected specimen pairs that were obtained at different times and/or different hospitals from the same patient, and compared their genotypes using standardized microsatellite markers used commonly for forensic human DNA comparison in order to identify unsuspected mismatches between the specimen pairs as a trial of "molecular auditing." We preferentially selected gastrointestinal, prostate, and skin biopsies because we estimated that these types of specimens had the greatest potential for misidentification. Results Of 972 specimen pairs, 1 showed an unexpected discordant genotype profile, indicating that 1 of the 2 specimens was misidentified. To date, we are unable to identify the etiology of the discordance. Conclusions These results demonstrate that, indeed, there is a low level of unsuspected tissue specimen misidentification, even in an environment with careful adherence to stringent quality assurance practices. This study demonstrates that molecular auditing of random, routine biopsy specimens can identify occult misidentified specimens, and may function as a useful quality indicator.

Drop-Weight Impact Test on U-Shape Concrete Specimens with Statistical and Regression Analyses

PubMed Central

Zhu, Xue-Chao; Zhu, Han; Li, Hao-Ran

2015-01-01

According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation. PMID:28793540

Elastic-Plastic Behaviour of Ultrasonic Assisted Compression of Polyvinyl Chloride (PVC) Foam

NASA Astrophysics Data System (ADS)

Muhalim, N. A. D.; Hassan, M. Z.; Daud, Y.

2018-04-01

The present study aims to investigate the elastic-plastic behaviour of ultrasonic assisted compression of PVC closed-cell foam. A series of static and ultrasonic compression test of PVC closed-cell foam were conducted at a constant cross head speed of 30 mm/min on dry surface condition. For quasi-static test, specimen was compressed between two rigid platens using universal testing machine. In order to evaluate the specimen behavior under ultrasonic condition, specimen was placed between a specifically design double-slotted block horn and rigid platen. The horn was designed and fabricated prior to the test as a medium to transmit the ultrasonic vibration from the ultrasonic transducer to the working specimen. It was tuned to a frequency of 19.89 kHz in longitudinal mode and provided an average oscillation amplitude at 6 µm on the uppermost surface. Following, the characteristics of stress-strain curves for quasi-static and ultrasonic compression tests were analyzed. It was found that the compressive stress was significantly reduced at the onset of superimposed ultrasonic vibration during plastic deformation.

Development of procedures for calculating stiffness and damping of elastomers in engineering applications. Part 5: Elastomer performance limits and the design and test of an elastomer damper

NASA Technical Reports Server (NTRS)

Tecza, J. A.; Darlow, M. S.; Smalley, A. J.

1979-01-01

Tests were performed on elastomer specimens of the material polybutadiene to determine the performance limitations imposed by strain, temperature, and frequency. Three specimens were tested: a shear specimen, a compression specimen, and a second compression specimen in which thermocouples were embedded in the elastomer buttons. Stiffness and damping were determined from all tests, and internal temperatures were recorded for the instrumented compression specimen. Measured results are presented together with comparisons between predictions of a thermo-viscoelastic analysis and the measured results. Dampers of polybutadiene and Viton were designed, built, and tested. Vibration measurements were made and sensitivity of vibration to change in unbalance was also determined. Values for log decrement were extracted from the synchronous response curves. Comparisons were made between measured sensitivity to unbalance and log decrement and predicted values for these quantities.

Performance of V-4Cr-4Ti material exposed to DIII-D tokamak environment

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

Tsai, H.; Chung, H.M.; Smith, D.L.

1997-04-01

Test specimens made with the 832665 heat of V-4Cr-4Ti alloy were exposed in the DIII-D tokamak environment to support the installation of components made of a V-4Cr-4Ti alloy in the radiative divertor of the DIII-D. Some of the tests were conducted with the Divertor Materials Evaluation System (DiMES) to study the short-term effects of postvent bakeout, when concentrations of gaseous impurities in the DIII-D chamber are the highest. Other specimens were mounted next to the chamber wall behind the divertor baffle plate, to study the effects of longer-term exposures. By design, none of the specimens directly interacted with the plasma.more » Preliminary results from testing the exposed specimens indicate only minor degradation of mechanical properties. Additional testing and microstructural characterization are in progress.« less

New procedure to reduce the time and cost of broncho-pulmonary specimen management using the Previ Isola® automated inoculation system.

PubMed

Nebbad-Lechani, Biba; Emirian, Aurélie; Maillebuau, Fabienne; Mahjoub, Nadia; Fihman, Vincent; Legrand, Patrick; Decousser, Jean-Winoc

2013-12-01

The microbiological diagnosis of respiratory tract infections requires serial manual dilutions of the clinical specimen before agar plate inoculation, disrupting the workflow in bacteriology clinical laboratories. Automated plating instrument systems have been designed to increase the speed, reproducibility and safety of this inoculating step; nevertheless, data concerning respiratory specimens are lacking. We tested a specific procedure that uses the Previ Isola® (bioMérieux, Craponne, France) to inoculate with broncho-pulmonary specimens (BPS). A total of 350 BPS from a university-affiliated hospital were managed in parallel using the manual reference and the automated methods (expectoration: 75; broncho-alveolar lavage: 68; tracheal aspiration: 17; protected distal sample: 190). A specific enumeration reading grid, a pre-liquefaction step and a fluidity test, performed before the inoculation, were designed for the automated method. The qualitative (i.e., the number of specimens yielding a bacterial count greater than the clinical threshold) and quantitative (i.e., the discrepancy within a 0.5 log value) concordances were 100% and 98.2%, respectively. The slimmest subgroup of expectorations could not be managed by the automated method (8%, 6/75). The technical time and cost savings (i.e., number of consumed plates) reached 50%. Additional studies are required for specific populations, such as cystic fibrosis specimens and associated bacterial variants. An automated decapper should be implemented to increase the biosafety of the process. The PREVI Isola® adapted procedure is a time- and cost-saving method for broncho-pulmonary specimen processing. © 2013.

Characterization of cementitiously stabilized subgrades for mechanistic-empirical pavement design

NASA Astrophysics Data System (ADS)

Solanki, Pranshoo

Pavements are vulnerable to subgrade layer performance because it acts as a foundation. Due to increase in the truck traffic, pavement engineers are challenged to build more strong and long-lasting pavements. To increase the load-bearing capacity of pavements, subgrade layer is often stabilized with cementitious additives. Thus, an overall characterization of stabilized subgrade layer is important for enhanced short- and long-term pavement performance. In this study, the effect of type and amount of additive on the short-term performance in terms of material properties recommended by the new Mechanistic-Empirical Pavement Design Guide (MEPDG) is examined. A total of four soils commonly encountered as subgrades in Oklahoma are utilized. Results show that the changes in the Mr, ME and UCS values stabilized specimens depend on the soil type and properties of additives. The long-term performance (or durability) of stabilized soil specimens is investigated by conducting freeze-thaw (F-T) cycling, vacuum saturation and tube suction tests on 7-day cured P-, K- and C-soil specimens stabilized with 6% lime, 10% CFA and 10% CKD. This study is motivated by the fact that during the service life of pavement stabilized layers are subjected to F-T cycles and moisture variations. It is found that that UCS value of all the stabilized specimens decreased with increase in the number of F-T cycles. A strong correlation was observed between UCS values retained after vacuum saturation and F-T cycles indicating that vacuum saturation could be used as a time-efficient and inexpensive method for evaluating durability of stabilized soils. In this study, short- and long-term observations from stabilization of sulfate bearing soil with locally available low (CFA), moderate (CKD) and high (lime) calcium-based stabilizers are determined to evaluate and compare the effect of additive type on the phenomenon of sulfate-induced heave. The impact of different factors on the development of the ettringite, responsible for sulfate-induced heaving, is also discussed. For Level 2 design of pavements, a total of four stress-based statistical models and two feed-forward-type artificial neural network (ANN) models, are evaluated for predicting resilient modulus of 28-day cured stabilized specimens. Specifically, one semi-log stress-based, three log-log stress-based, one Multi-Layer Perceptrons Network (MLPN), and one Radial Basis Function Network (RBFN) are developed. Overall, semi-log stress-based and MLPN neural network are found to show best acceptable performance for the present evaluation and validation datasets. Further, correlations are presented for stress-based models to correlate Mr with compacted specimen characteristics and soil/additive properties. Additionally, the effect of type of additive on indirect tensile and fatigue characteristics of selected stabilized P- and V-soil is evaluated. This study is based on the fact that stabilized layer is subjected to tensile stresses under wheel loading. Thus, the resilient modulus in tension (M rt), fatigue life and strength in tension (sigmat) or flexure (represented by modulus of rupture, MOR) becomes another important design parameter within the mechanistic framework. Cylindrical specimens are prepared, cured for 28 days and subjected to different stress sequences in indirect tension to study the Mrt. On the other hand, stabilized beam specimens are compacted using a Linear Kneading Compactor and subjected to repeated cycles of reloading-unloading after 28 days of curing in a four-point beam fatigue apparatus for evaluating fatigue life and flexural stiffness. It is found that all three additives improved the Mrt, sigmat and MOR values; however, degree of improvement varied with the type of additive and soil. This study encompasses the differences in the design of semi-rigid pavements developed using AASHTO 1993 and AASHTO 2002 MEPDG methodologies. Further, the design curves for fatigue performance prediction of stabilized layers are developed for different stabilized pavement sections. Knowledge gained from the parametric analysis of different sections using AASHTO 1993 and MEPDG is expected to be useful to pavement designers and others in implementation of the new MEPDG for future pavement design. (Abstract shortened by UMI.)

Advanced composite vertical stabilizer for DC-10 transport aircraft

NASA Technical Reports Server (NTRS)

Stephens, C. O.

1978-01-01

The structural design configuration for the Composite Vertical Stabilizer is described and the structural design, analysis, and weight activities are presented. The status of fabrication and test activities for the development test portion of the program is described. Test results are presented for the skin panels, spar web, spar cap to cover, and laminate properties specimens. Engineering drawings of vertification test panels and root fittings, rudder support specimens, titanium fittings, and rear spar specimen analysis models are included.

Design and fabrication of a micron scale free-standing specimen for uniaxial micro-tensile tests

NASA Astrophysics Data System (ADS)

Tang, Jun; Wang, Hong; Li, Shi Chen; Liu, Rui; Mao, Sheng Ping; Li, Xue Ping; Zhang, Cong Chun; Ding, Guifu

2009-10-01

This paper presents a novel design and fabrication of test chips with a nickel free-standing specimen for the micro uniaxial tensile test. To fabricate test chips on the quartz substrate significantly reduces the fabrication time, minimizes the number of steps and eliminates the effect of the wet anisotropic etching process on mechanical properties. The test chip can be gripped tightly to the test machine and aligned accurately in the pulling direction; furthermore, the approximately straight design of the specimen rather than the traditional dog-bone structure enables the strain be directly measured by a displacement sensor. Both finite-element method (FEM) analysis and experimental results indicate the reliability of the new design. The test chip can also be extended to other materials. The experimental measured Young's modulus of a thin nickel film and the ultimate tensile strength are approximately 94.5 Gpa and 1.76 Gpa, respectively. The results were substantially supported by the experiment on larger gauge specimens by a commercial dynamic mechanical analysis (DMA) instrument. These specimens were electroplated under the same conditions. The low Young's modulus and the high ultimate tensile strength might be explained by the fine grain in the electroplated structure.

An electronic specimen collection protocol schema (eSCPS). Document architecture for specimen management and the exchange of specimen collection protocols between biobanking information systems.

PubMed

Eminaga, O; Semjonow, A; Oezguer, E; Herden, J; Akbarov, I; Tok, A; Engelmann, U; Wille, S

2014-01-01

The integrity of collection protocols in biobanking is essential for a high-quality sample preparation process. However, there is not currently a well-defined universal method for integrating collection protocols in the biobanking information system (BIMS). Therefore, an electronic schema of the collection protocol that is based on Extensible Markup Language (XML) is required to maintain the integrity and enable the exchange of collection protocols. The development and implementation of an electronic specimen collection protocol schema (eSCPS) was performed at two institutions (Muenster and Cologne) in three stages. First, we analyzed the infrastructure that was already established at both the biorepository and the hospital information systems of these institutions and determined the requirements for the sufficient preparation of specimens and documentation. Second, we designed an eSCPS according to these requirements. Finally, a prospective study was conducted to implement and evaluate the novel schema in the current BIMS. We designed an eSCPS that provides all of the relevant information about collection protocols. Ten electronic collection protocols were generated using the supplementary Protocol Editor tool, and these protocols were successfully implemented in the existing BIMS. Moreover, an electronic list of collection protocols for the current studies being performed at each institution was included, new collection protocols were added, and the existing protocols were redesigned to be modifiable. The documentation time was significantly reduced after implementing the eSCPS (5 ± 2 min vs. 7 ± 3 min; p = 0.0002). The eSCPS improves the integrity and facilitates the exchange of specimen collection protocols in the existing open-source BIMS.

Test Methodology Development for Experimental Structural Assessment of ASC Planar Spring Material for Long-Term Durability

NASA Technical Reports Server (NTRS)

Yun, Gunjin; Abdullah, A. B. M.; Binienda, Wieslaw; Krause, David L.; Kalluri, Sreeramesh

2014-01-01

A vibration-based testing methodology has been developed that will assess fatigue behavior of the metallic material of construction for the Advanced Stirling Convertor displacer (planar) spring component. To minimize the testing duration, the test setup is designed for base-excitation of a multiplespecimen arrangement, driven in a high-frequency resonant mode; this allows completion of fatigue testing in an accelerated period. A high performance electro-dynamic exciter (shaker) is used to generate harmonic oscillation of cantilever beam specimens, which are clasped on the shaker armature with specially-designed clamp fixtures. The shaker operates in closed-loop control with dynamic specimen response feedback provided by a scanning laser vibrometer. A test coordinator function synchronizes the shaker controller and the laser vibrometer to complete the closed-loop scheme. The test coordinator also monitors structural health of the test specimens throughout the test period, recognizing any change in specimen dynamic behavior. As this may be due to fatigue crack initiation, the test coordinator terminates test progression and then acquires test data in an orderly manner. Design of the specimen and fixture geometry was completed by finite element analysis such that peak stress does not occur at the clamping fixture attachment points. Experimental stress evaluation was conducted to verify the specimen stress predictions. A successful application of the experimental methodology was demonstrated by validation tests with carbon steel specimens subjected to fully-reversed bending stress; high-cycle fatigue failures were induced in such specimens using higher-than-prototypical stresses

THE TYPES OF PALAEARCTIC HIPPORHININI (Coleoptera, Curculionidae, Cyclominae) CONSERVED AT THE MUSÉUM NATIONAL D'HISTOIRE NATURELLE, PARIS.

PubMed

Meregalli, Massimo; Perrin, Hélène

2015-11-30

The Palaearctic species of Curculionidae: Cyclominae: Hipporhinini conserved at the Muséum national d'Histoire Naturelle, Paris were critically revised in order to recognise the type specimens, select lectotypes or, where necessary, designate neotypes. Out of 135 species whose types were presumably preserved in the MNHN, original type specimens of 116 could be found. The holotypes of 21 species were available, either because originally designated as such, or because the species was unequivocally based on a single specimen; a paratype of another taxon, whose holotype is preserved in another collection, was also examined. The lectotypes of 93 species were designated, and a syntype of another species was also seen. Neotypes of 10 more species were designated, thus leading to a total number of species whose type is conserved at the MNHN to 126. Type specimens of five more species described by French authors, not present in the MNHN but conserved in other museums, were found as well and were included in the paper, with the further designation of three lectotypes. All types treated herein were labelled and photographed.

A procedure for scaling sensory attributes based on multidimensional measurements: application to sensory sharpness of kitchen knives

NASA Astrophysics Data System (ADS)

Takatsuji, Toshiyuki; Tanaka, Ken-ichi

1996-06-01

A procedure is derived by which sensory attributes can be scaled as a function of various physical and/or chemical properties of the object to be tested. This procedure consists of four successive steps: (i) design and experiment, (ii) fabrication of specimens according to the design parameters, (iii) assessment of a sensory attribute using sensory evaluation and (iv) derivation of the relationship between the parameters and the sensory attribute. In these steps an experimental design using orthogonal arrays, analysis of variance and regression analyses are used strategically. When a specimen with the design parameters cannot be physically fabricated, an alternative specimen having parameters closest to the design is selected from a group of specimens which can be physically made. The influence of the deviation of actual parameters from the desired ones is also discussed. A method of confirming the validity of the regression equation is also investigated. The procedure is applied to scale the sensory sharpness of kitchen knives as a function of the edge angle and the roughness of the cutting edge.

Statistical approaches for the determination of cut points in anti-drug antibody bioassays.

PubMed

Schaarschmidt, Frank; Hofmann, Matthias; Jaki, Thomas; Grün, Bettina; Hothorn, Ludwig A

2015-03-01

Cut points in immunogenicity assays are used to classify future specimens into anti-drug antibody (ADA) positive or negative. To determine a cut point during pre-study validation, drug-naive specimens are often analyzed on multiple microtiter plates taking sources of future variability into account, such as runs, days, analysts, gender, drug-spiked and the biological variability of un-spiked specimens themselves. Five phenomena may complicate the statistical cut point estimation: i) drug-naive specimens may contain already ADA-positives or lead to signals that erroneously appear to be ADA-positive, ii) mean differences between plates may remain after normalization of observations by negative control means, iii) experimental designs may contain several factors in a crossed or hierarchical structure, iv) low sample sizes in such complex designs lead to low power for pre-tests on distribution, outliers and variance structure, and v) the choice between normal and log-normal distribution has a serious impact on the cut point. We discuss statistical approaches to account for these complex data: i) mixture models, which can be used to analyze sets of specimens containing an unknown, possibly larger proportion of ADA-positive specimens, ii) random effects models, followed by the estimation of prediction intervals, which provide cut points while accounting for several factors, and iii) diagnostic plots, which allow the post hoc assessment of model assumptions. All methods discussed are available in the corresponding R add-on package mixADA. Copyright © 2015 Elsevier B.V. All rights reserved.

Design and dosimetry of small animal radiation facilities

NASA Astrophysics Data System (ADS)

Rodriguez, Manuel R.

The aim of this work was to develop an irradiation system for radiobiology studies. We designed a novel image-guided micro-irradiator capable of partial-body zebrafish embryo irradiation. The radiation source is a 50 kV photon beam from a miniature x-ray source (Xoft Inc., CA). The source is inserted in a cylindrical brass collimator, 3 cm in diameter and 3 cm in length. The collimator has a 1 mm-diameter pinhole along the longitudinal axis, which provides a well-focused beam with a sharp penumbra. A photodiode is installed at one exit of the pinhole collimator to monitor the photon dose rate. The source with the collimator is attached under a movable table. A video camera, connected to the computer, is placed above the movable table to record position of the specimens in relation to the pinhole collimator. The captured images are analyzed, and the relative distances between the specimens and the pinhole are calculated. The coordinates are sent to the computer-controlled movable table to accurately position the specimens in the beam. Monte Carlo simulations were performed to characterize dosimetric properties of the system, to determine dosimetric sensitivity, and to help in the design. The image-guidance and high precision of the movable table enable very accurate specimen position. The beam monitoring system provides accurate, fast and easy dose determination. Portability and self-shielding make this system suitable for any radiobiology laboratory. This novel micro-irradiator is appropriate for partial irradiation of zebrafish embryos; however its potential use is much wider like irradiation of cell cultures or other small specimens.

Design of a Resistively Heated Thermal Hydraulic Simulator for Nuclear Rocket Reactor Cores

NASA Technical Reports Server (NTRS)

Litchford, Ron J.; Foote, John P.; Ramachandran, Narayanan; Wang, Ten-See; Anghaie, Samim

2007-01-01

A preliminary design study is presented for a non-nuclear test facility which uses ohmic heating to replicate the thermal hydraulic characteristics of solid core nuclear reactor fuel element passages. The basis for this testing capability is a recently commissioned nuclear thermal rocket environments simulator, which uses a high-power, multi-gas, wall-stabilized constricted arc-heater to produce high-temperature pressurized hydrogen flows representative of reactor core environments, excepting radiation effects. Initially, the baseline test fixture for this non-nuclear environments simulator was configured for long duration hot hydrogen exposure of small cylindrical material specimens as a low cost means of evaluating material compatibility. It became evident, however, that additional functionality enhancements were needed to permit a critical examination of thermal hydraulic effects in fuel element passages. Thus, a design configuration was conceived whereby a short tubular material specimen, representing a fuel element passage segment, is surrounded by a backside resistive tungsten heater element and mounted within a self-contained module that inserts directly into the baseline test fixture assembly. With this configuration, it becomes possible to create an inward directed radial thermal gradient within the tubular material specimen such that the wall-to-gas heat flux characteristics of a typical fuel element passage are effectively simulated. The results of a preliminary engineering study for this innovative concept are fully summarized, including high-fidelity multi-physics thermal hydraulic simulations and detailed design features.

An in-situ study in SEM of delamination in several graphite/epoxy composite material systems

NASA Technical Reports Server (NTRS)

Bradley, W. L.

1986-01-01

A three point bend fixture compatible with the current loading stage for the Scanning Electron Microscope was designed and fabricated. End-notched flexure tests were run on several materials. Work to date was on AS4/3502, T6T145/F155, and T6T145/F185. Fracture toughness was measured. Fracture of neat resin specimens was begun. The decrease in delaminatin fracture toughness, compared to neat resin toughness, due to rigid fiber filler and interlaminar failure is addressed. An experimental program was designed to try to determine the proper interpretatin for apparent microcracking in neat resin specimens.

Study of foldable elastic tubes for large space structure applications, phase 1

NASA Technical Reports Server (NTRS)

Jones, I. W.; Boateng, C.; Williams, C. D.

1980-01-01

Structural members that might be suitable for strain energy deployable structures, are discussed with emphasis on a thin-walled cylindrical tube with a cross-section that is called 'bi-convex'. The design of bi-convex tube test specimens and their fabrication are described as well as the design and construction of a special purpose testing machine to determine the deployment characteristics. The results of the first series of tests were quite mixed, but clearly revealed that since most of the specimens failed to deploy completely, due to a buckling problem, this type of tube requires some modification in order to be viable.

Reliability of concentrations of organophosphate pesticide metabolites in serial urine specimens from pregnancy in the Generation R Study.

PubMed

Spaan, Suzanne; Pronk, Anjoeka; Koch, Holger M; Jusko, Todd A; Jaddoe, Vincent W V; Shaw, Pamela A; Tiemeier, Henning M; Hofman, Albert; Pierik, Frank H; Longnecker, Matthew P

2015-05-01

The widespread use of organophosphate (OP) pesticides has resulted in ubiquitous exposure in humans, primarily through their diet. Exposure to OP pesticides may have adverse health effects, including neurobehavioral deficits in children. The optimal design of new studies requires data on the reliability of urinary measures of exposure. In the present study, urinary concentrations of six dialkyl phosphate (DAP) metabolites, the main urinary metabolites of OP pesticides, were determined in 120 pregnant women participating in the Generation R Study in Rotterdam. Intra-class correlation coefficients (ICCs) across serial urine specimens taken at <18, 18-25, and >25 weeks of pregnancy were determined to assess reliability. Geometric mean total DAP metabolite concentrations were 229 (GSD 2.2), 240 (GSD 2.1), and 224 (GSD 2.2) nmol/g creatinine across the three periods of gestation. Metabolite concentrations from the serial urine specimens in general correlated moderately. The ICCs for the six DAP metabolites ranged from 0.14 to 0.38 (0.30 for total DAPs), indicating weak to moderate reliability. Although the DAP metabolite levels observed in this study are slightly higher and slightly more correlated than in previous studies, the low to moderate reliability indicates a high degree of within-person variability, which presents challenges for designing well-powered epidemiological studies.

Advanced manufacturing development of a composite empennage component for L-1011 aircraft

NASA Technical Reports Server (NTRS)

1979-01-01

Work on process verification and tooling development continued. The cover process development was completed with the decision to proceed with low resin content prepreg material (34 + or - 3% by weight) in the fabrication of production readiness verification test (PRVT) specimens and the full-scale covers. The structural integrity of the cover/joint design was verified with the successful test of the cover attachment to fuselage ancillary test specimen (H25). Failure occurred, as predicted, in the skin panel away from the fuselage joint at 141 percent of the design ultimate load. With the successful completion of the H25 test, the PRVT cover specimens, which are identical to the H25 ancillary test specimen, were cleared for production. Eight of the twenty cover specimens were fabricated and are in preparation for test. All twenty of the PRVT spar specimens were fabricated and also were prepared for test. The environmental chambers used in the durability test of ten cover and ten spar PRVT specimens were completed and installed in the load reaction frames.

Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

NASA Technical Reports Server (NTRS)

Westfall, L. J.; Petrasek, D. W.

1985-01-01

Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760C (1400 F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

Thermal-mechanical fatigue test apparatus for metal matrix composites and joint attachments

NASA Technical Reports Server (NTRS)

Westfall, Leonard J.; Petrasek, Donald W.

1988-01-01

Two thermal-mechanical fatigue (TMF) test facilities were designed and developed, one to test tungsten fiber reinforced metal matrix composite specimens at temperature up to 1430C (2600F) and another to test composite/metal attachment bond joints at temperatures up to 760F (1400F). The TMF facility designed for testing tungsten fiber reinforced metal matrix composites permits test specimen temperature excursions from room temperature to 1430C (2600F) with controlled heating and loading rates. A strain-measuring device measures the strain in the test section of the specimen during each heating and cooling cycle with superimposed loads. Data is collected and recorded by a computer. The second facility is designed to test composite/metal attachment bond joints and to permit heating to a maximum temperature of 760C (1400F) within 10 min and cooling to 150C (300F) within 3 min. A computer controls specimen temperature and load cycling.

2015 Accomplishments-Tritium aging studies on stainless steel. Effects of hydrogen isotopes, crack orientation, and specimen geometry on fracture toughness

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

Morgan, Michael J.

This study reports on the effects of hydrogen isotopes, crack orientation, and specimen geometry on the fracture toughness of stainless steels. Fracture toughness variability was investigated for Type 21-6-9 stainless steel using the 7K0004 forging. Fracture toughness specimens were cut from the forging in two different geometric configurations: arc shape and disc shape. The fracture toughness properties were measured at ambient temperature before and after exposure to hydrogen gas and compared to prior studies. There are three main conclusions that can be drawn from the results. First, the fracture toughness properties of actual reservoir forgings and contemporary heats of steelmore » are much higher than those measured in earlier studies that used heats of steel from the 1980s and 1990s and forward extruded forgings which were designed to simulate reservoir microstructures. This is true for as-forged heats as well as forged heats exposed to hydrogen gas. Secondly, the study confirms the well-known observation that cracks oriented parallel to the forging grain flow will propagate easier than those oriented perpendicular to the grain flow. However, what was not known, but is shown here, is that this effect is more pronounced, particularly after hydrogen exposures, when the forging is given a larger upset. In brick forgings, which have a relatively low amount of upset, the fracture toughness variation with specimen orientation is less than 5%; whereas, in cup forgings, the fracture toughness is about 20% lower than that forging to show how specimen geometry affects fracture toughness values. The American Society for Testing Materials (ASTM) specifies minimum specimen section sizes for valid fracture toughness values. However, sub-size specimens have long been used to study tritium effects because of the physical limitation of diffusing hydrogen isotopes into stainless steel at mild temperatures so as to not disturb the underlying forged microstructure. This study shows that fracture toughness values of larger specimens are higher and more representative of the material’s fracture behavior in a fully constrained tritium reservoir. The toughness properties measured for sub-size specimens were about 65-75% of the values for larger specimens. While the data from sub-size specimens are conservative, they may be overly so. The fracture toughness properties from sub-size specimens are valuable in that they can be used for tritium effects studies and show the same trends and alloy differences as those seen from larger specimen data. Additional work is planned, including finite element modeling, to see if sub-size specimen data could be adjusted in some way to be more closely aligned with the actual material behavior in a fully constrained pressure vessel.« less

Pulsed-voltage atom probe tomography of low conductivity and insulator materials by application of ultrathin metallic coating on nanoscale specimen geometry.

PubMed

Adineh, Vahid R; Marceau, Ross K W; Chen, Yu; Si, Kae J; Velkov, Tony; Cheng, Wenlong; Li, Jian; Fu, Jing

2017-10-01

We present a novel approach for analysis of low-conductivity and insulating materials with conventional pulsed-voltage atom probe tomography (APT), by incorporating an ultrathin metallic coating on focused ion beam prepared needle-shaped specimens. Finite element electrostatic simulations of coated atom probe specimens were performed, which suggest remarkable improvement in uniform voltage distribution and subsequent field evaporation of the insulated samples with a metallic coating of approximately 10nm thickness. Using design of experiment technique, an experimental investigation was performed to study physical vapor deposition coating of needle specimens with end tip radii less than 100nm. The final geometries of the coated APT specimens were characterized with high-resolution scanning electron microscopy and transmission electron microscopy, and an empirical model was proposed to determine the optimal coating thickness for a given specimen size. The optimal coating strategy was applied to APT specimens of resin embedded Au nanospheres. Results demonstrate that the optimal coating strategy allows unique pulsed-voltage atom probe analysis and 3D imaging of biological and insulated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Concepts for improving the damage tolerance of composite compression panels. [aircraft structures

NASA Technical Reports Server (NTRS)

Rhodes, M. D.; Williams, J. G.

1984-01-01

The residual strength of specimens with damage and the sensitivity to damage while subjected to an applied inplane compression load were determined for flatplate specimens and blade-stiffened panels. The results suggest that matrix materials that fail by delamination have the lowest damage tolerance capability. Alternate matrix materials or laminates which are transversely reinforced suppress the delamination mode of failure and change the failure mode to transverse shear crippling which occurs at a higher strain value. Several damage-tolerant blade-stiffened panel design concepts are evaluated. Structural efficiency studies conducted show only small mass penalties may result from incorporating these damage-tolerant features in panel design. The implication of test results on the design of aircraft structures was examined with respect to FAR requirements.

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Skoumal, D. E.

1980-01-01

Bonded and bolted designs are presented for each of four major attachment types. Prepreg processing problems are discussed and quality control data are given for lots 2W4604, 2W4632 and 2W4643. Preliminary design allowables test results for tension tests and compression tests of laminates are included. The final small specimen test matrix is defined and the configuration of symmetric step-lap joint specimens are shown. Finite element modeling studies of a double lap joint were performed to evaluate the number of elements required through the adhesive thickness to assess effects of various joint parameters on stress distributions. Results of finite element analyses assessing the effect of an adhesive fillet on the stress distribution in a double lap joint are examined.

Three alternative structural configurations for phlebotomy: a comparison of effectiveness.

PubMed

Mannion, Heidi; Nadder, Teresa

2007-01-01

This study was designed to compare the effectiveness of three alternative structural configurations for inpatient phlebotomy. It was hypothesized that decentralized was less effective when compared to centralized inpatient phlebotomy. A non-experimental prospective survey design was conducted at the institution level. Laboratory managers completed an organizational survey and collected data on inpatient blood specimens during a 30-day data collection period. A random sample (n=31) of hospitals with onsite laboratories in the United States was selected from a database purchased from the Joint Commission on Accreditations of Healthcare Organizations (JCAHO). Effectiveness of the blood collection process was measured by the percentage of specimens rejected during the data collection period. Analysis of variance showed a statistically significant difference in the percentage of specimens rejected for centralized, hybrid, and decentralized phlebotomy configurations [F (2, 28) = 4.27, p = .02] with an effect size of .23. Post-hoc comparison using Tukey's HSD indicated that mean percentage of specimens rejected for centralized phlebotomy (M = .045, SD = 0.36) was significantly different from the decentralized configuration (M = 1.42, SD = 0.92, p = .03). found to be more effective when compared to the decentralized configuration.

Titanium honeycomb acoustic lining structural and thermal test report. [for acoustic tailpipe for JT8D engine

NASA Technical Reports Server (NTRS)

Joynes, D.; Balut, J. P.

1974-01-01

The results are presented of static, fatigue and thermal testing of titanium honeycomb acoustic panels representing the acoustic tailpipe for the Pratt and Whitney Aircraft JT8D Refan engine which is being studied for use on the Boeing 727-200 airplane. Test specimens represented the engine and tailpipe flange joints, the rail to which the thrust reverser is attached and shear specimens of the tailpipe honeycomb. Specimens were made in four different batches with variations in configuration, materials and processes in each. Static strength of all test specimens exceeded the design ultimate load requirements. Fatigue test results confirmed that aluminum brazed titanium, as used in the Refan tailpipe design, meets the fatigue durability objectives. Quality of welding was found to be critical to life, with substandard welding failing prematurely, whereas welding within the process specification exceeded the panel skin life. Initial fatigue testing used short grip length bolts which failed prematurely. These were replaced with longer bolts and subsequent testing demonstrated the required life. Thermal tests indicate that perforated skin acoustic honeycomb has approximately twice the heat transfer of solid skin honeycomb.

Design, fabrication and test of graphite/polymide composite joints and attachments: Summary

NASA Technical Reports Server (NTRS)

Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

1983-01-01

The design, analysis and testing performed to develop four types of graphite/polyimide (Gr/PI) bonded and bolted composite joints for lightly loaded control surfaces on advanced space transportation systems that operate at temperatures up to 561K (550 F) are summarized. Material properties and 'small specimen' tests were conducted to establish design data and to evaluate specific design details. 'Static discriminator' tests were conducted on preliminary designs to verify structural adequacy. Scaled up specimens of the final joint designs, representative of production size requirements, were subjected to a series of static and fatigue tests to evaluate joint strength. Effects of environmental conditioning were determined by testing aged (125 hours 589K (600 F)) and thermal cycled (116K to 589K (-250 F to 600 F), 125 times) specimens. It is concluded Gr/PI joints can be designed and fabricated to carry the specified loads. Test results also indicate a possible resin loss or degradation of laminates after exposure to 589K (600 F) for 125 hours.

Design, fabrication and test of graphite/polyimide composite joints and attachments. [spacecraft control surfaces

NASA Technical Reports Server (NTRS)

Cushman, J. B.; Mccleskey, S. F.; Ward, S. H.

1982-01-01

The design, analysis, and testing performed to develop four types of graphite/polyimide (Gr/PI) bonded and bolted composite joints for lightly loaded control surfaces on advanced space transportation systems that operate at temperatures up to 561 K (550 F) are summarized. Material properties and small specimen tests were conducted to establish design data and to evaluate specific design details. Static discriminator tests were conducted on preliminary designs to verify structural adequacy. Scaled up specimens of the final joint designs, representative of production size requirements, were subjected to a series of static and fatigue tests to evaluate joint strength. Effects of environmental conditioning were determined by testing aged (125 hours at 589 K (600 F)) and thermal cycled (116 K to 589 K (-250 F to 600 F), 125 times) specimens. It is concluded Gr/PI joints can be designed and fabricated to carry the specified loads. Test results also indicate a possible resin loss or degradation of laminates after exposure to 589 K (600 F) for 125 hours.

Inselect: Automating the Digitization of Natural History Collections

PubMed Central

Hudson, Lawrence N.; Blagoderov, Vladimir; Heaton, Alice; Holtzhausen, Pieter; Livermore, Laurence; Price, Benjamin W.; van der Walt, Stéfan; Smith, Vincent S.

2015-01-01

The world’s natural history collections constitute an enormous evidence base for scientific research on the natural world. To facilitate these studies and improve access to collections, many organisations are embarking on major programmes of digitization. This requires automated approaches to mass-digitization that support rapid imaging of specimens and associated data capture, in order to process the tens of millions of specimens common to most natural history collections. In this paper we present Inselect—a modular, easy-to-use, cross-platform suite of open-source software tools that supports the semi-automated processing of specimen images generated by natural history digitization programmes. The software is made up of a Windows, Mac OS X, and Linux desktop application, together with command-line tools that are designed for unattended operation on batches of images. Blending image visualisation algorithms that automatically recognise specimens together with workflows to support post-processing tasks such as barcode reading, label transcription and metadata capture, Inselect fills a critical gap to increase the rate of specimen digitization. PMID:26599208

Inselect: Automating the Digitization of Natural History Collections.

PubMed

Hudson, Lawrence N; Blagoderov, Vladimir; Heaton, Alice; Holtzhausen, Pieter; Livermore, Laurence; Price, Benjamin W; van der Walt, Stéfan; Smith, Vincent S

2015-01-01

The world's natural history collections constitute an enormous evidence base for scientific research on the natural world. To facilitate these studies and improve access to collections, many organisations are embarking on major programmes of digitization. This requires automated approaches to mass-digitization that support rapid imaging of specimens and associated data capture, in order to process the tens of millions of specimens common to most natural history collections. In this paper we present Inselect-a modular, easy-to-use, cross-platform suite of open-source software tools that supports the semi-automated processing of specimen images generated by natural history digitization programmes. The software is made up of a Windows, Mac OS X, and Linux desktop application, together with command-line tools that are designed for unattended operation on batches of images. Blending image visualisation algorithms that automatically recognise specimens together with workflows to support post-processing tasks such as barcode reading, label transcription and metadata capture, Inselect fills a critical gap to increase the rate of specimen digitization.

Simple Magnetic Device Indicates Thickness Of Alloy 903

NASA Technical Reports Server (NTRS)

Long, Pin Jeng; Rodriguez, Sergio; Bright, Mark L.

1995-01-01

Handheld device called "ferrite indicator" orginally designed for use in determining ferrite content of specimen of steel. Placed in contact with specimen and functions by indicating whether magnet attracted more strongly to specimen or to calibrated reference sample. Relative strength of attraction shows whether alloy overlay thinner than allowable.

CARES/Life Software for Designing More Reliable Ceramic Parts

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Powers, Lynn M.; Baker, Eric H.

1997-01-01

Products made from advanced ceramics show great promise for revolutionizing aerospace and terrestrial propulsion, and power generation. However, ceramic components are difficult to design because brittle materials in general have widely varying strength values. The CAPES/Life software eases this task by providing a tool to optimize the design and manufacture of brittle material components using probabilistic reliability analysis techniques. Probabilistic component design involves predicting the probability of failure for a thermomechanically loaded component from specimen rupture data. Typically, these experiments are performed using many simple geometry flexural or tensile test specimens. A static, dynamic, or cyclic load is applied to each specimen until fracture. Statistical strength and SCG (fatigue) parameters are then determined from these data. Using these parameters and the results obtained from a finite element analysis, the time-dependent reliability for a complex component geometry and loading is then predicted. Appropriate design changes are made until an acceptable probability of failure has been reached.

Damage Tolerant Design for Cold-Section Turbine Engine Disks

DTIC Science & Technology

1981-06-01

Ti-6Al-4V Disks ......... .. 59 28. FIOO 2nd-Stage Fan Disk Designs ........ ................ .. 61 29. Fan Disk Tangential Stress Profile... 61 30. Life-Limiting Features of Damage-Tolerant Disk .......... ... 62 31. Disk Life Limits .... ...................... 62 32. Life Test...Stress Rati• Model ..... .......... .. 113 61 . Thick-Section Center-Notched Specimen ....... ............. .. 116 62. Bolthole Specimen

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

Barclay, D. L.

1980-01-01

Results of an experimental program to develop several types of graphite/polyimide (GR/PI) bonded and bolted joints for lightly loaded flight components for advanced space transportation systems and high speed aircraft are presented. Tasks accomplished include: a literature survey; design of static discriminator specimens; design allowables testing; fabrication of test panels and specimens; small specimen testing; and standard joint testing. Detail designs of static discriminator specimens for each of the four major attachment types are presented. Test results are given for the following: (1) transverse tension of Celion 3000/PMR-15 laminate; (2) net tension of a laminate for both a loaded and unloaded bolt hole; (3) comparative testing of bonded and co-cured doublers along with pull-off tests of single and double bonded angles; (4) single lap shear tests, transverse tension and coefficient of thermal expansion tests of A7F (LARC-13 amide-imide modified) adhesive; and (5) tension tests of standard single lap, double lap, and symmetric step lap bonded joints. Also, included are results of a finite element analysis of a single lap bonded composite joint.

Design, fabrication and test of graphite/polyimide composite joints and attachments for advanced aerospace vehicles

NASA Technical Reports Server (NTRS)

1980-01-01

Principal program activities dealt with the literature survey, design of joint concepts, assessment of GR/PI material quality, fabrication of test panels and specimens, and small specimen testing. Bonded and bolted designs are presented for each of the four major attachment types. Quality control data are presented for prepreg Lots 2W4651 and 3W2020. Preliminary design allowables test results for tension tests and compression tests of laminates are also presented.

Plant Disease Severity Assessment-How Rater Bias, Assessment Method, and Experimental Design Affect Hypothesis Testing and Resource Use Efficiency.

PubMed

Chiang, Kuo-Szu; Bock, Clive H; Lee, I-Hsuan; El Jarroudi, Moussa; Delfosse, Philippe

2016-12-01

The effect of rater bias and assessment method on hypothesis testing was studied for representative experimental designs for plant disease assessment using balanced and unbalanced data sets. Data sets with the same number of replicate estimates for each of two treatments are termed "balanced" and those with unequal numbers of replicate estimates are termed "unbalanced". The three assessment methods considered were nearest percent estimates (NPEs), an amended 10% incremental scale, and the Horsfall-Barratt (H-B) scale. Estimates of severity of Septoria leaf blotch on leaves of winter wheat were used to develop distributions for a simulation model. The experimental designs are presented here in the context of simulation experiments which consider the optimal design for the number of specimens (individual units sampled) and the number of replicate estimates per specimen for a fixed total number of observations (total sample size for the treatments being compared). The criterion used to gauge each method was the power of the hypothesis test. As expected, at a given fixed number of observations, the balanced experimental designs invariably resulted in a higher power compared with the unbalanced designs at different disease severity means, mean differences, and variances. Based on these results, with unbiased estimates using NPE, the recommended number of replicate estimates taken per specimen is 2 (from a sample of specimens of at least 30), because this conserves resources. Furthermore, for biased estimates, an apparent difference in the power of the hypothesis test was observed between assessment methods and between experimental designs. Results indicated that, regardless of experimental design or rater bias, an amended 10% incremental scale has slightly less power compared with NPEs, and that the H-B scale is more likely than the others to cause a type II error. These results suggest that choice of assessment method, optimizing sample number and number of replicate estimates, and using a balanced experimental design are important criteria to consider to maximize the power of hypothesis tests for comparing treatments using disease severity estimates.

Preparation of reconstituted Charpy V-notch impact specimens for generating pressure vessel steel fracture toughness data

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

Perrin, J.S.; Fromm, E.O.; Server, W.L.

1982-01-01

The arc stud welding process has been adapted for use in producing reconstituted Charpy V-notch impact specimens. In this process, each half of a tested and fractured Charpy specimen is used as the central region of a reconstituted specimen. End tabs are joined to one half of a fractured specimen by a specially designed stud welding apparatus. SA533B-1 and SA508-2 unirradiated and irradiated pressure vessel steel specimens have been produced. Both conventional and precracked reconstituted specimen data have been produced. Both types of data have been shown to be in excellent agreement with original specimen data. The arc stud weldingmore » process can therefore be used to increase the amount of data obtainable from a limited number of specimens or to obtain Charpy data when full size specimens cannot otherwise be obtained.« less

Independent Predictors of Prognosis Based on Oral Cavity Squamous Cell Carcinoma Surgical Margins.

PubMed

Buchakjian, Marisa R; Ginader, Timothy; Tasche, Kendall K; Pagedar, Nitin A; Smith, Brian J; Sperry, Steven M

2018-05-01

Objective To conduct a multivariate analysis of a large cohort of oral cavity squamous cell carcinoma (OCSCC) cases for independent predictors of local recurrence (LR) and overall survival (OS), with emphasis on the relationship between (1) prognosis and (2) main specimen permanent margins and intraoperative tumor bed frozen margins. Study Design Retrospective cohort study. Setting Tertiary academic head and neck cancer program. Subjects and Methods This study included 426 patients treated with OCSCC resection between 2005 and 2014 at University of Iowa Hospitals and Clinics. Patients underwent excision of OCSCC with intraoperative tumor bed frozen margin sampling and main specimen permanent margin assessment. Multivariate analysis of the data set to predict LR and OS was performed. Results Independent predictors of LR included nodal involvement, histologic grade, and main specimen permanent margin status. Specifically, the presence of a positive margin (odds ratio, 6.21; 95% CI, 3.3-11.9) or <1-mm/carcinoma in situ margin (odds ratio, 2.41; 95% CI, 1.19-4.87) on the main specimen was an independent predictor of LR, whereas intraoperative tumor bed margins were not predictive of LR on multivariate analysis. Similarly, independent predictors of OS on multivariate analysis included nodal involvement, extracapsular extension, and a positive main specimen margin. Tumor bed margins did not independently predict OS. Conclusion The main specimen margin is a strong independent predictor of LR and OS on multivariate analysis. Intraoperative tumor bed frozen margins do not independently predict prognosis. We conclude that emphasis should be placed on evaluating the main specimen margins when estimating prognosis after OCSCC resection.

Postbuckling behavior of graphite-epoxy panels

NASA Technical Reports Server (NTRS)

Starnes, J. H., Jr.; Dickson, J. N.; Rouse, M.

1984-01-01

Structurally efficient fuselage panels are often designed to allow buckling to occur at applied loads below ultimate. Interest in applying graphite-epoxy materials to fuselage primary structure led to several studies of the post-buckling behavior of graphite-epoxy structural components. Studies of the postbuckling behavior of flat and curved, unstiffened and stiffened graphite-epoxy panels loaded in compression and shear were summarized. The response and failure characteristics of specimens studied experimentally were described, and analytical and experimental results were compared. The specimens tested in the studies described were fabricated from commercially available 0.005-inch-thick unidirectional graphite-fiber tapes preimpregnated with 350 F cure thermosetting epoxy resins.

New Technique for Tibiotalar Arthrodesis Using a New Intramedullary Nail Device: A Cadaveric Study

PubMed Central

Eisenstein, Emmanuel D.; Rodriguez, Mario

2016-01-01

Introduction. Ankle arthrodesis is performed in a variety of methods. We propose a new technique for tibiotalar arthrodesis using a newly designed intramedullary nail. Methods. We proposed development of an intramedullary device for ankle arthrodesis which spared the subtalar joint using a sinus tarsi approach. Standard saw bones models and computer assisted modeling and stress analysis were used to develop different nail design geometries and determine the feasibility of insertion. After the final design was constructed, the device was tested on three cadaveric specimens. Results. Four basic nail geometries were developed. The optimal design was composed of two relatively straight segments, each with a different radius of curvature for their respective tibial and talar component. We successfully implemented this design into three cadaveric specimens. Conclusion. Our newly designed tibiotalar nail provides a new technique for isolated tibiotalar fusion. It utilizes the advantages of a tibiotalar calcaneal nail and spares the subtalar joint. This design serves as the foundation for future research to include compression options across the tibiotalar joint and eventual transition to clinical practice. PMID:27818800

New Technique for Tibiotalar Arthrodesis Using a New Intramedullary Nail Device: A Cadaveric Study.

PubMed

Eisenstein, Emmanuel D; Rodriguez, Mario; Abdelgawad, Amr A

2016-01-01

Introduction . Ankle arthrodesis is performed in a variety of methods. We propose a new technique for tibiotalar arthrodesis using a newly designed intramedullary nail. Methods . We proposed development of an intramedullary device for ankle arthrodesis which spared the subtalar joint using a sinus tarsi approach. Standard saw bones models and computer assisted modeling and stress analysis were used to develop different nail design geometries and determine the feasibility of insertion. After the final design was constructed, the device was tested on three cadaveric specimens. Results . Four basic nail geometries were developed. The optimal design was composed of two relatively straight segments, each with a different radius of curvature for their respective tibial and talar component. We successfully implemented this design into three cadaveric specimens. Conclusion . Our newly designed tibiotalar nail provides a new technique for isolated tibiotalar fusion. It utilizes the advantages of a tibiotalar calcaneal nail and spares the subtalar joint. This design serves as the foundation for future research to include compression options across the tibiotalar joint and eventual transition to clinical practice.

Designing a biomechanics investigation: choosing the right model.

PubMed

Olson, Steven A; Marsh, J Lawrence; Anderson, Donald D; Latta Pe, Loren L

2012-12-01

Physical testing is commonly performed to answer important biomechanical questions in the treatment of patients with fractures and other orthopaedic conditions. However, a variety of mistakes that are made in performing such investigations can severely limit their impact. The goal of this article is to discuss important aspects of study design to consider when planning for biomechanical investigations so that the studies can provide maximal benefit to the field. The best mechanical investigations begin with a good research question, one that comes out of patient care experience, is clearly defined, and can be stated concisely. The first practical issue to be considered is often choosing the type of physical specimens to be tested to address the research question. A related issue involves determining how many specimens will be needed to answer the posed mechanical question. Cadavers are generally still the closest to the actual clinical situation, but they are limited by interspecimen variability, which often requires a matched pair design that can address only one question. Simulated bone specimens limit variability and can replicate normal and osteoporotic bone. In planning the physical testing, the critical mechanical variables involved in answering the research question must be identified and due consideration given to deciding how best to measure them. Another important issue that arises relates to whether or not single static loadings will suffice in the testing (eg, to study construct stiffness) or whether cyclic dynamic testing is necessary (eg, to study late failure likely attributable to fatigue). To summarize, experimental design should be carefully planned before initiating mechanical testing. Sample size calculations should be performed to ensure adequate power and that clinically relevant differences can be detected. This pregame analysis can save significant time and cost and greatly increase the likelihood that the results will advance knowledge.

Identification of Unique Metabolites of the Designer Opioid Furanyl Fentanyl.

PubMed

Goggin, Melissa M; Nguyen, An; Janis, Gregory C

2017-06-01

The illicit drug market has seen an increase in designer opioids, including fentanyl and methadone analogs, and other structurally unrelated opioid agonists. The designer opioid, furanyl fentanyl, is one of many fentanyl analogs clandestinely synthesized for recreational use and contributing to the fentanyl and opioid crisis. A method has been developed and validated for the analysis of furanyl fentanyl and furanyl norfentanyl in urine specimens from pain management programs. Approximately 10% of samples from a set of 500 presumptive heroin-positive urine specimens were found to contain furanyl fentanyl, with an average concentration of 33.8 ng/mL, and ranging from 0.26 to 390 ng/mL. Little to no furanyl norfentanyl was observed; therefore, the furanyl fentanyl specimens were further analyzed by untargeted high-resolution mass spectrometry to identify other metabolites. Multiple metabolites, including a dihydrodiol metabolite, 4-anilino-N-phenethyl-piperidine (4-ANPP) and a sulfate metabolite were identified. The aim of the presented study was to identify the major metabolite(s) of furanyl fentanyl and estimate their concentrations for the purpose of toxicological monitoring. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The neotype barcode of the cotton aphid (Hemiptera: Aphididae: Aphis gossypii Glover, 1877) and a proposal for type barcodes

USDA-ARS?s Scientific Manuscript database

A type barcode is a DNA barcode unequivocally tied to an authoritatively identified specimen, preferably the primary type specimen. Type barcodes are analogous, albeit subordinate, to type specimens, providing a stable reference to which other barcodes can be compared. We here designate and describe...

Reliability of concentrations of organophosphate pesticide metabolites in serial urine specimens from pregnancy in the Generation R study

PubMed Central

Spaan, Suzanne; Pronk, Anjoeka; Koch, Holger M.; Jusko, Todd A.; Jaddoe, Vincent W.V.; Shaw, Pamela A.; Tiemeier, Henning M.; Hofman, Albert; Pierik, Frank H.; Longnecker, Matthew P.

2014-01-01

The widespread use of organophosphate (OP) pesticides has resulted in ubiquitous exposure in humans, primarily through their diet. Exposure to OP pesticides may have adverse health effects, including neurobehavioral deficits in children. The optimal design of new studies requires data on the reliability of urinary measures of exposure. In the present study, urinary concentrations of six dialkyl phosphate (DAP) metabolites, the main urinary metabolites of OP pesticides, were determined in 120 pregnant women participating in the Generation R Study in Rotterdam. Intra-class correlation coefficients (ICCs) across serial urine specimens taken at <18, 18–25, and >25 weeks of pregnancy were determined to assess reliability. Geometric mean total DAP metabolite concentrations were 229 (GSD 2.2), 240 (GSD 2.1), and 224 (GSD 2.2) nmol/g creatinine across the three periods of gestation. Metabolite concentrations from the serial urine specimens in general correlated moderately. The ICCs for the six DAP metabolites ranged from 0.14 to 0.38 (0.30 for total DAPs), indicating weak to moderate reliability. Although the DAP metabolite levels observed in this study are slightly higher and slightly more correlated than in previous studies, the low to moderate reliability indicates a high degree of within-person variability, which presents challenges for designing well-powered epidemiologic studies. PMID:25515376

Effect of silica fume on compressive strength of oil-polluted concrete in different marine environments

NASA Astrophysics Data System (ADS)

Shahrabadi, Hamid; Sayareh, Sina; Sarkardeh, Hamed

2017-12-01

In the present research, effect of silica fume as an additive and oil polluted sands as aggregates on compressive strength of concrete were investigated experimentally. The amount of oil in the designed mixtures was assumed to be constant and equal to 2% of the sand weight. Silica fume accounting for 10%, 15% and 20% of the weight is added to the designed mixture. After preparation and curing, concrete specimens were placed into the three different conditions: fresh, brackish and saltwater environments (submerged in fresh water, alternation of exposed in air & submerged in sea water and submerged in sea water). The result of compressive strength tests shows that the compressive strength of the specimens consisting of silica fume increases significantly in comparison with the control specimens in all three environments. The compressive strength of the concrete with 15% silica fume content was about 30% to 50% higher than that of control specimens in all tested environments under the condition of using polluted aggregates in the designed mixture.

Scanning Tunneling Microscope For Use In Vacuum

NASA Technical Reports Server (NTRS)

Abel, Phillip B.

1993-01-01

Scanning tunneling microscope with subangstrom resolution developed to study surface structures. Although instrument used in air, designed especially for use in vacuum. Scanning head is assembly of small, mostly rigid components made of low-outgassing materials. Includes coarse-positioning mechanical-translation stage, on which specimen mounted by use of standard mounting stub. Tunneling tip mounted on piezoelectric fine-positioning tube. Application of suitable voltages to electrodes on piezoelectric tube controls scan of tunneling tip across surface of specimen. Electronic subsystem generates scanning voltages and collects data.

Subcritical water liquefaction of oil palm fruit press fiber in the presence of sodium hydroxide: an optimisation study using response surface methodology.

PubMed

Mazaheri, Hossein; Lee, Keat Teong; Bhatia, Subhash; Mohamed, Abdul Rahman

2010-12-01

Thermal decomposition of oil palm fruit press fiber (FPF) into a liquid product (LP) was achieved using subcritical water treatment in the presence of sodium hydroxide in a high pressure batch reactor. This study uses experimental design and process optimisation tools to maximise the LP yield using response surface methodology (RSM) with central composite rotatable design (CCRD). The independent variables were temperature, residence time, particle size, specimen loading, and additive loading. The mathematical model that was developed fit the experimental results well for all of the response variables that were studied. The optimal conditions were found to be a temperature of 551 K, a residence time of 40 min, a particle size of 710-1000 microm, a specimen loading of 5 g, and a additive loading of 9 wt.% to achieve a LP yield of 76.16%. 2010 Elsevier Ltd. All rights reserved.

Species selection in secondary wood products: implications for product design and promotion

Treesearch

Matthew S. Bumgardner; Scott A. Bowe; Scott A. Bowe

2002-01-01

This study investigated the perceptions that people have of several commercially important wood species and determined if word-based and specimen-based evaluations differed. Such knowledge can help secondary wood manufacturers better understand their products and develop more effective design concepts and promotional messages. A sample of more than 250 undergraduate...

Flat tensile specimen design for advanced composites

NASA Technical Reports Server (NTRS)

Worthem, Dennis W.

1990-01-01

Finite element analyses of flat, reduced gage section tensile specimens with various transition region contours were performed. Within dimensional constraints, such as maximum length, tab region width, gage width, gage length, and minimum tab length, a transition contour radius of 41.9 cm produced the lowest stress values in the specimen transition region. The stresses in the transition region were not sensitive to specimen material properties. The stresses in the tab region were sensitive to specimen composite and/or tab material properties. An evaluation of stresses with different specimen composite and tab material combinations must account for material nonlinearity of both the tab and the specimen composite. Material nonlinearity can either relieve stresses in the composite under the tab or elevate them to cause failure under the tab.

Impact damage and residual strength analysis of composite panels with bonded stiffeners. [for primary aircraft structures

NASA Technical Reports Server (NTRS)

Madan, Ram C.; Shuart, Mark J.

1990-01-01

Blade-stiffened, compression-loaded cover panels were designed, manufactured, analyzed, and tested. All panels were fabricated from IM6/1808I interleafed graphite-epoxy. An orthotropic blade stiffener and an orthotropic skin were selected to satisfy the design requirements for an advanced aircraft configuration. All specimens were impact damaged prior to testing. Experimental results were obtained for three- and five-stiffener panels. Analytical results described interlaminar forces caused by impact and predicted specimen residual strength. The analytical results compared reasonably with the experimental results for residual strength of the specimens.

37 CFR 1.166 - Specimens.

Code of Federal Regulations, 2010 CFR

2010-07-01

... COMMERCE GENERAL RULES OF PRACTICE IN PATENT CASES National Processing Provisions Plant Patents § 1.166... quantity and at a time in its stage of growth as may be designated, for study and inspection. Such...

Surgical Specimen Management: A Descriptive Study of 648 Adverse Events and Near Misses.

PubMed

Steelman, Victoria M; Williams, Tamara L; Szekendi, Marilyn K; Halverson, Amy L; Dintzis, Suzanne M; Pavkovic, Stephen

2016-12-01

- Surgical specimen adverse events can lead to delays in treatment or diagnosis, misdiagnosis, reoperation, inappropriate treatment, and anxiety or serious patient harm. - To describe the types and frequency of event reports associated with the management of surgical specimens, the contributing factors, and the level of harm associated with these events. - A retrospective review was undertaken of surgical specimen adverse events and near misses voluntarily reported in the University HealthSystem Consortium Safety Intelligence Patient Safety Organization database by more than 50 health care facilities during a 3-year period (2011-2013). Event reports that involved surgical specimen management were reviewed for patients undergoing surgery during which tissue or fluid was sent to the pathology department. - Six hundred forty-eight surgical specimen events were reported in all stages of the specimen management process, with the most common events reported during the prelaboratory phase and, specifically, with specimen labeling, collection/preservation, and transport. The most common contributing factors were failures in handoff communication, staff inattention, knowledge deficit, and environmental issues. Eight percent of the events (52 of 648) resulted in either the need for additional treatment or temporary or permanent harm to the patient. - All phases of specimen handling and processing are vulnerable to errors. These results provide a starting point for health care organizations to conduct proactive risk analyses of specimen handling procedures and to design safer processes. Particular attention should be paid to effective communication and handoffs, consistent processes across care areas, and staff training. In addition, organizations should consider the use of technology-based identification and tracking systems.

Seismic design repair and retrofit strategies for steel roof deck diaphragms

NASA Astrophysics Data System (ADS)

Franquet, John-Edward

Structural engineers will often rely on the roof diaphragm to transfer lateral seismic loads to the bracing system of single-storey structures. The implementation of capacity-based design in the NBCC 2005 has caused an increase in the diaphragm design load due to the need to use the probable capacity of the bracing system, thus resulting in thicker decks, closer connector patterns and higher construction costs. Previous studies have shown that accounting for the in-plane flexibility of the diaphragm when calculating the overall building period can result in lower seismic forces and a more cost-efficient design. However, recent studies estimating the fundamental period of single storey structures using ambient vibration testing showed that the in-situ approximation was much shorter than that obtained using analytical means. The difference lies partially in the diaphragm stiffness characteristics which have been shown to decrease under increasing excitation amplitude. Using the diaphragm as the energy-dissipating element in the seismic force resisting system has also been investigated as this would take advantage of the diaphragm's ductility and limited overstrength; thus, lower capacity based seismic forces would result. An experimental program on 21.0m by 7.31m diaphragm test specimens was carried out so as to investigate the dynamic properties of diaphragms including the stiffness, ductility and capacity. The specimens consisted of 20 and 22 gauge panels with nailed frame fasteners and screwed sidelap connections as well a welded and button-punch specimen. Repair strategies for diaphragms that have previously undergone inelastic deformations were devised in an attempt to restitute the original stiffness and strength and were then experimentally evaluated. Strength and stiffness experimental estimations are compared with those predicted with the Steel Deck Institute (SDI) method. A building design comparative study was also completed. This study looks at the difference in design and cost yielded by previous and current design practice with EBF braced frames. Two alternate design methodologies, where the period is not restricted by code limitations and where the diaphragm force is limited to the equivalent shear force calculated with RdR o = 1.95, are also used for comparison. This study highlights the importance of incorporating the diaphragm stiffness in design and the potential cost savings.

Genomic treasure troves: complete genome sequencing of herbarium and insect museum specimens.

PubMed

Staats, Martijn; Erkens, Roy H J; van de Vossenberg, Bart; Wieringa, Jan J; Kraaijeveld, Ken; Stielow, Benjamin; Geml, József; Richardson, James E; Bakker, Freek T

2013-01-01

Unlocking the vast genomic diversity stored in natural history collections would create unprecedented opportunities for genome-scale evolutionary, phylogenetic, domestication and population genomic studies. Many researchers have been discouraged from using historical specimens in molecular studies because of both generally limited success of DNA extraction and the challenges associated with PCR-amplifying highly degraded DNA. In today's next-generation sequencing (NGS) world, opportunities and prospects for historical DNA have changed dramatically, as most NGS methods are actually designed for taking short fragmented DNA molecules as templates. Here we show that using a standard multiplex and paired-end Illumina sequencing approach, genome-scale sequence data can be generated reliably from dry-preserved plant, fungal and insect specimens collected up to 115 years ago, and with minimal destructive sampling. Using a reference-based assembly approach, we were able to produce the entire nuclear genome of a 43-year-old Arabidopsis thaliana (Brassicaceae) herbarium specimen with high and uniform sequence coverage. Nuclear genome sequences of three fungal specimens of 22-82 years of age (Agaricus bisporus, Laccaria bicolor, Pleurotus ostreatus) were generated with 81.4-97.9% exome coverage. Complete organellar genome sequences were assembled for all specimens. Using de novo assembly we retrieved between 16.2-71.0% of coding sequence regions, and hence remain somewhat cautious about prospects for de novo genome assembly from historical specimens. Non-target sequence contaminations were observed in 2 of our insect museum specimens. We anticipate that future museum genomics projects will perhaps not generate entire genome sequences in all cases (our specimens contained relatively small and low-complexity genomes), but at least generating vital comparative genomic data for testing (phylo)genetic, demographic and genetic hypotheses, that become increasingly more horizontal. Furthermore, NGS of historical DNA enables recovering crucial genetic information from old type specimens that to date have remained mostly unutilized and, thus, opens up a new frontier for taxonomic research as well.

A universal fluid cell for the imaging of biological specimens in the atomic force microscope.

PubMed

Kasas, Sandor; Radotic, Ksenja; Longo, Giovanni; Saha, Bashkar; Alonso-Sarduy, Livan; Dietler, Giovanni; Roduit, Charles

2013-04-01

Recently, atomic force microscope (AFM) manufacturers have begun producing instruments specifically designed to image biological specimens. In most instances, they are integrated with an inverted optical microscope, which permits concurrent optical and AFM imaging. An important component of the set-up is the imaging chamber, whose design determines the nature of the experiments that can be conducted. Many different imaging chamber designs are available, usually designed to optimize a single parameter, such as the dimensions of the substrate or the volume of fluid that can be used throughout the experiment. In this report, we present a universal fluid cell, which simultaneously optimizes all of the parameters that are important for the imaging of biological specimens in the AFM. This novel imaging chamber has been successfully tested using mammalian, plant, and microbial cells. Copyright © 2013 Wiley Periodicals, Inc.

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.

Design, Fabrication and Test of Composite Curved Frames for Helicopter Fuselage Structure

NASA Technical Reports Server (NTRS)

Lowry, D. W.; Krebs, N. E.; Dobyns, A. L.

1984-01-01

Aspects of curved beam effects and their importance in designing composite frame structures are discussed. The curved beam effect induces radial flange loadings which in turn causes flange curling. This curling increases the axial flange stresses and induces transverse bending. These effects are more important in composite structures due to their general inability to redistribute stresses by general yielding, such as in metal structures. A detailed finite element analysis was conducted and used in the design of composite curved frame specimens. Five specimens were statically tested and compared with predicted and test strains. The curved frame effects must be accurately accounted for to avoid premature fracture; finite element methods can accurately predict most of the stresses and no elastic relief from curved beam effects occurred in the composite frames tested. Finite element studies are presented for comparative curved beam effects on composite and metal frames.

Design and implementation of the canadian kidney disease cohort study (CKDCS): A prospective observational study of incident hemodialysis patients

PubMed Central

2011-01-01

Background Many nephrology observational studies use renal registries, which have well known limitations. The Canadian Kidney Disease Cohort Study (CKDCS) is a large prospective observational study of patients commencing hemodialysis in five Canadian centers. This study focuses on delineating potentially reversible determinants of adverse outcomes that occur in patients receiving dialysis for end-stage renal disease (ESRD). Methods/Design The CKDCS collects information on risk factors and outcomes, and stores specimens (blood, dialysate, hair and fingernails) at baseline and in long-term follow-up. Such specimens will permit measurements of biochemical markers, proteomic and genetic parameters (proteins and DNA) not measured in routine care. To avoid selection bias, all consenting incident hemodialysis patients at participating centers are enrolled, the large sample size (target of 1500 patients), large number of exposures, and high event rates will permit the exploration of multiple potential research questions. Preliminary Results Data on the baseline characteristics from the first 1074 subjects showed that the average age of patients was 62 (range; 50-73) years. The leading cause of ESRD was diabetic nephropathy (41.9%), and the majority of the patients were white (80.0%). Only 18.7% of the subjects received dialysis in a satellite unit, and over 80% lived within a 50 km radius of the nearest nephrologist's practice. Discussion The prospective design, detailed clinical information, and stored biological specimens provide a wealth of information with potential to greatly enhance our understanding of risk factors for adverse outcomes in dialysis patients. The scientific value of the stored patient tissue will grow as new genetic and biochemical markers are discovered in the future. PMID:21324196

Mitochondrial DNA in Residual Leukemia Cells in Cerebrospinal Fluid in Children with Acute Lymphoblastic Leukemia

PubMed Central

Egan, Kathryn; Kusao, Ian; Troelstrup, David; Agsalda, Melissa; Shiramizu, Bruce

2010-01-01

This feasibility study was designed to assess the ability to measure mitochondrial DNA (mtDNA) in cerebrospinal fluid (CSF) cells that contributed to minimal disease/persistent or residual disease (MD/PRD) from children with acute lymphoblastic leukemia (ALL). Increase in mtDNA copies in cancer cells has been suggested to play a role in MD/PRD. CSF as well as blood specimens from 6 children were assayed for MD/PRD and mtDNA copy numbers by quantitative real-time polymerase chain reaction. Of 7 MD/PRD-positive specimens, 6 had increased mtDNA copy numbers; while 11 MD/PRD-negative specimens had no increase in mtDNA copy numbers, p < 0.003. This is the first proof-of-concept study to measure mtDNA copy numbers in MD/PRD-positive CSF specimens from children with ALL. Increase of mtDNA copy numbers in MD/PRD childhood ALL cells and its significance as a mechanism for recurrence requires further investigation. Keywords Minimal residual disease; Acute lymphoblastic leukemia; Central nervous system; Cerebrospinal fluid; Mitochondria PMID:21331151

16 CFR 1615.4 - Test procedure.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Specimen holder. The specimen holder is designed to permit suspension of the specimen in a fixed vertical... series of loads for char length determinations. Suitable metal hooks consist of No. 19 gauge steel wire... least 8 h at 21±1.1 °C (70±2 °F) and 65±2 pct relative humidity. Shorter conditioning times may be used...

Monitoring the use of anatomical teaching material using a low-cost radio frequency identification system: A comprehensive assessment.

PubMed

Noël, Geoffroy P J C; Connolly, Ciaran C

2016-01-01

The correct tracking and monitoring of anatomical specimens is not only imperative in any modern body donation programs but also in any universities for which teaching the next generation of health care professionals is the primary mission. This has long been an arduous process for anatomy institutions across the world, and the recent focus of new curricula on self-directed learning adds new stress on specimens which are used by students. The radio frequency identification (RFID) technology has been proposed as a very effective tracking system in healthcare considering that it enables automatic identification and data capture of multiple items at once. In this study, the feasibility of a low-cost RFID inventory system is assessed, from its design to the performance of commercially available RFID tags in a gross anatomy laboratory. The results show that ultrahigh frequency-based RFID tags successfully performed when attached to a collection of 112 plastinated and 280 wet dissected specimens. Comparison analysis of different tags reveals, however, that careful selection of RFID tags needs to be considered when wet specimens need to be tracked as preservation fluids can absorb radio waves energy. This study demonstrates that it is economically feasible to incorporate RFID technology to closely monitor the use of anatomical teaching specimens. The described RFID inventory system was not only able to preserve the integrity of the specimens being used by limiting handling and therefore human error but was also able to identify missing or misplaced specimens and to update their status. © 2015 American Association of Anatomists.

A method for predicting the fatigue life of pre-corroded 2024-T3 aluminum from breaking load tests

NASA Astrophysics Data System (ADS)

Gruenberg, Karl Martin

Characterization of material properties is necessary for design purposes and has been a topic of research for many years. Over the last several decades, much progress has been made in identifying metrics to describe fracture mechanics properties and developing procedures to measure the appropriate values. However, in the context of design, there has not been as much success in quantifying the susceptibility of a material to corrosion damage and its subsequent impact on material behavior in the framework of fracture mechanics. A natural next step in understanding the effects of corrosion damage was to develop a link between standard material test procedures and fatigue life in the presence of corrosion. Simply stated, the goal of this investigation was to formulate a cheaper and quicker method for assessing the consequences of corrosion on remaining fatigue life. For this study, breaking load specimens and fatigue specimens of a single nominal gage (0.063″) of aluminum alloy 2024-T3 were exposed to three levels of corrosion. The breaking load specimens were taken from three different material lots, and the fatigue tests were carried out at three stress levels. All failed specimens, both breaking load and fatigue specimens, were examined to characterize the damage state(s) and failure mechanism(s). Correlations between breaking load results and fatigue life results in the presence of corrosion damage were developed using a fracture mechanics foundation and the observed mechanisms of failure. Where breaking load tests showed a decrease in strength due to increased corrosion exposure, the corresponding set of fatigue tests showed a decrease in life. And where breaking load tests from different specimen orientations exhibited similar levels of strength, the corresponding set of fatigue specimens showed similar lives. The spread from shortest to longest fatigue lives among the different corrosion conditions decreased at the higher stress levels. Life predictions based on breaking load data were generally shorter than the experimental lives by an average of 20%. The life prediction methodology developed from this investigation is a very valuable tool for the purpose of assessing material substitution for aircraft designers, alloy differentiation for manufacturers, or inspection intervals and aircraft retirement schedules for aircraft in service.

Human papillomavirus DNA in the urogenital tracts of men with gonorrhoea, penile warts or genital dermatoses.

PubMed Central

Hillman, R J; Ryait, B K; Botcherby, M; Taylor-Robinson, D

1993-01-01

OBJECTIVE--To assess the presence of human papillomavirus (HPV) DNA in urethral and urine specimens from men with and without sexually transmitted diseases. DESIGN--Prospective study. SETTING--Two London departments of genitourinary medicine PATIENTS--100 men with urethral gonorrhoea, 31 men with penile warts and 37 men with genital dermatoses. METHODS--Urethral and urine specimens were taken, HPV DNA extracted and then amplified using the polymerase chain reaction. HPV types 6, 11, 16, 18, 31 and 33 were identified using Southern blotting followed by hybridisation. RESULTS--HPV DNA was detected in 18-31% of urethral swab specimens and in 0-14% of urine specimens. Men with penile warts had HPV detected in urethral swabs more often than did men in the other two clinical groups. "High risk" HPV types were found in 71-83% of swab specimens and in 73-80% of urine specimens containing HPV DNA. CONCLUSIONS--HPV is present in the urogenital tracts of men with gonorrhoea, penile warts and with genital dermatoses. In men with urethral gonorrhoea, detection of HPV in urethral specimens is not related to the number of sexual partners, condom usage, racial origin or past history of genital warts. HPV DNA in the urethral swab and urine specimens may represent different aspects of the epidemiology of HPV in the male genital tract. The preponderance of HPV types 16 and 18 in all three groups of men may be relevant to the concept of the "high risk male". Images PMID:8392967

Evaluation of a dried blood and plasma collection device, SampleTanker(®), for HIV type 1 drug resistance genotyping in patients receiving antiretroviral therapy.

PubMed

Diallo, Karidia; Lehotzky, Erica; Zhang, Jing; Zhou, Zhiyong; de Rivera, Ivette Lorenzana; Murillo, Wendy E; Nkengasong, John; Sabatier, Jennifer; Zhang, Guoqing; Yang, Chunfu

2014-01-01

Whatman 903 filter paper is the only filter paper that has been used for HIV drug resistance (HIVDR) genotyping in resource-limited settings. In this study, we evaluated another dried blood specimen collection device, termed SampleTanker(®) (ST), for HIVDR genotyping. Blood specimens from 123 antiretroviral therapy (ART)-experienced patients were used to prepare ST whole blood and ST plasma specimens; they were then stored at ambient temperature for 2 or 4 weeks. The remaining plasma specimens were stored at -80°C and used as frozen plasma controls. Frozen plasma viral load (VL) was determined using the Roche Amplicor HIV-1 Monitor test, v.1.5 and 50 specimens with VL ≥3.00 log10 copies/ml were genotyped using the broadly sensitive genotyping assay. The medium VL for the 50 frozen plasma specimens with VL ≥3.00 log10 was 3.58 log10 copies/ml (IQR: 3.32-4.11) and 96.0% (48/50) of them were genotyped. Comparing to frozen plasma specimens, significantly lower genotyping rates were obtained from ST whole blood (48.98% and 42.85%) and ST plasma specimens (36.0% and 36.0%) stored at ambient temperature for 2 and 4 weeks, respectively (p<0.001). Nucleotide sequence identity and resistance profile analyses between the matched frozen plasma and ST whole blood or ST plasma specimens revealed high nucleotide sequence identities and concordant resistance profiles (98.1% and 99.0%, and 96.6% and 98.9%, respectively). Our results indicate that with the current design, the ST may not be the ideal dried blood specimen collection device for HIVDR monitoring for ART patients in resource-limited settings.

Probabilistic Composite Design

NASA Technical Reports Server (NTRS)

Chamis, Christos C.

1997-01-01

Probabilistic composite design is described in terms of a computational simulation. This simulation tracks probabilistically the composite design evolution from constituent materials, fabrication process, through composite mechanics and structural components. Comparisons with experimental data are provided to illustrate selection of probabilistic design allowables, test methods/specimen guidelines, and identification of in situ versus pristine strength, For example, results show that: in situ fiber tensile strength is 90% of its pristine strength; flat-wise long-tapered specimens are most suitable for setting ply tensile strength allowables: a composite radome can be designed with a reliability of 0.999999; and laminate fatigue exhibits wide-spread scatter at 90% cyclic-stress to static-strength ratios.

Design and evaluation of low cost blades for large wind driven generating systems

NASA Technical Reports Server (NTRS)

Eggert, W. S.

1982-01-01

The development and evaluation of a low cost blade concept based on the NASA-Lewis specifications is discussed. A blade structure was designed and construction methods and materials were selected. Complete blade tooling concepts, various technical and economic analysis, and evaluations of the blade design were performed. A comprehensive fatigue test program was conducted to provide data and to verify the design. A test specimen of the spar assembly, including the root end attachment, was fabricated. This is a full-scale specimen of the root end configuration, 20 ft long. A blade design for the Mod '0' system was completed.

Grips for Lightweight Tensile Specimens

NASA Technical Reports Server (NTRS)

Witte, William G., Jr.; Gibson, Walter D.

1987-01-01

Set of grips developed for tensile testing of lightweight composite materials. Double-wedge design substantially increases gripping force and reduces slippage. Specimen held by grips made of hardened wedges. Assembly screwed into load cell in tensile-testing machine.

Experimental Studies on Behaviour of Reinforced Geopolymer Concrete Beams Subjected to Monotonic Static Loading

NASA Astrophysics Data System (ADS)

Madheswaran, C. K.; Ambily, P. S.; Dattatreya, J. K.; Ramesh, G.

2015-06-01

This work describes the experimental investigation on behaviour of reinforced GPC beams subjected to monotonic static loading. The overall dimensions of the GPC beams are 250 mm × 300 mm × 2200 mm. The effective span of beam is 1600 mm. The beams have been designed to be critical in shear as per IS:456 provisions. The specimens were produced from a mix incorporating fly ash and ground granulated blast furnace slag, which was designed for a compressive strength of 40 MPa at 28 days. The reinforced concrete specimens are subjected to curing at ambient temperature under wet burlap. The parameters being investigated include shear span to depth ratio (a/d = 1.5 and 2.0). Experiments are conducted on 12 GPC beams and four OPCC control beams. All the beams are tested using 2000 kN servo-controlled hydraulic actuator. This paper presents the results of experimental studies.

A study of elevated temperature testing techniques for the fatigue behavior of PMCS: Application to T650-35/AMB21

NASA Technical Reports Server (NTRS)

Gyekenyesi, Andrew L.; Gastelli, Michael G.; Ellis, John R.; Burke, Christopher S.

1995-01-01

An experimental study was conducted to investigate the mechanical behavior of a T650-35/AMB21 eight-harness satin weave polymer composite system. Emphasis was placed on the development and refinement of techniques used in elevated temperature uniaxial PMC testing. Issues such as specimen design, gripping, strain measurement, and temperature control and measurement were addressed. Quasi-static tensile and fatigue properties (R(sub sigma) = 0.1) were examined at room and elevated temperatures. Stiffness degradation and strain accumulation during fatigue cycling were recorded to monitor damage progression and provide insight for future analytical modeling efforts. Accomplishments included an untabbed dog-bone specimen design which consistently failed in the gage section, accurate temperature control and assessment, and continuous in-situ strain measurement capability during fatigue loading at elevated temperatures. Finally, strain accumulation and stiffness degradation during fatigue cycling appeared to be good indicators of damage progression.

Clinical biochemistry laboratory rejection rates due to various types of preanalytical errors.

PubMed

Atay, Aysenur; Demir, Leyla; Cuhadar, Serap; Saglam, Gulcan; Unal, Hulya; Aksun, Saliha; Arslan, Banu; Ozkan, Asuman; Sutcu, Recep

2014-01-01

Preanalytical errors, along the process from the beginning of test requests to the admissions of the specimens to the laboratory, cause the rejection of samples. The aim of this study was to better explain the reasons of rejected samples, regarding to their rates in certain test groups in our laboratory. This preliminary study was designed on the rejected samples in one-year period, based on the rates and types of inappropriateness. Test requests and blood samples of clinical chemistry, immunoassay, hematology, glycated hemoglobin, coagulation and erythrocyte sedimentation rate test units were evaluated. Types of inappropriateness were evaluated as follows: improperly labelled samples, hemolysed, clotted specimen, insufficient volume of specimen and total request errors. A total of 5,183,582 test requests from 1,035,743 blood collection tubes were considered. The total rejection rate was 0.65 %. The rejection rate of coagulation group was significantly higher (2.28%) than the other test groups (P < 0.001) including insufficient volume of specimen error rate as 1.38%. Rejection rates of hemolysis, clotted specimen and insufficient volume of sample error were found to be 8%, 24% and 34%, respectively. Total request errors, particularly, for unintelligible requests were 32% of the total for inpatients. The errors were especially attributable to unintelligible requests of inappropriate test requests, improperly labelled samples for inpatients and blood drawing errors especially due to insufficient volume of specimens in a coagulation test group. Further studies should be performed after corrective and preventive actions to detect a possible decrease in rejecting samples.

Detection of Head and Neck Cancer in Surgical Specimens Using Quantitative Hyperspectral Imaging.

PubMed

Lu, Guolan; Little, James V; Wang, Xu; Zhang, Hongzheng; Patel, Mihir R; Griffith, Christopher C; El-Deiry, Mark W; Chen, Amy Y; Fei, Baowei

2017-09-15

Purpose: This study intends to investigate the feasibility of using hyperspectral imaging (HSI) to detect and delineate cancers in fresh, surgical specimens of patients with head and neck cancers. Experimental Design: A clinical study was conducted in order to collect and image fresh, surgical specimens from patients ( N = 36) with head and neck cancers undergoing surgical resection. A set of machine-learning tools were developed to quantify hyperspectral images of the resected tissue in order to detect and delineate cancerous regions which were validated by histopathologic diagnosis. More than two million reflectance spectral signatures were obtained by HSI and analyzed using machine-learning methods. The detection results of HSI were compared with autofluorescence imaging and fluorescence imaging of two vital-dyes of the same specimens. Results: Quantitative HSI differentiated cancerous tissue from normal tissue in ex vivo surgical specimens with a sensitivity and specificity of 91% and 91%, respectively, and which was more accurate than autofluorescence imaging ( P < 0.05) or fluorescence imaging of 2-NBDG ( P < 0.05) and proflavine ( P < 0.05). The proposed quantification tools also generated cancer probability maps with the tumor border demarcated and which could provide real-time guidance for surgeons regarding optimal tumor resection. Conclusions: This study highlights the feasibility of using quantitative HSI as a diagnostic tool to delineate the cancer boundaries in surgical specimens, and which could be translated into the clinic application with the hope of improving clinical outcomes in the future. Clin Cancer Res; 23(18); 5426-36. ©2017 AACR . ©2017 American Association for Cancer Research.

A novel design for storage of inner stress by colloidal processing on rock-like materials

NASA Astrophysics Data System (ADS)

Chen, Weichang; Wang, Sijing; Lekan Olatayo, Afolagboye; Fu, Huanran

2018-06-01

Inner stress exists in rocks, affecting rock engineering, yet has received very little attention and quantitative investigation because of uncertainty about its characteristics. Previous studies have suggested that the inner stresses of rock materials are closely related to their physical state variation. In this work, a novel mold was designed to simulate the storage process of inner stress in specimens composed of quartz sands and epoxy. Then, thermal tests were carried out to change the physical state of the specimens, and expansion of the specimens was monitored. The results indicated that inner stress could be partly locked by the mold and it could also be released by heating. It can be inferred from the analysis that one necessary condition of storage and release of inner stress is physical state variation. Additionally, by using an XRD method, the variations in the interplanar spacing of the quartz sands were detected, and the results reflect that inner stress could be locked-in aggregates (quartz sands) by a cement constraint (solid epoxy). The inner stress stored in quartz sands was calculated using height and interplanar spacing variations.

Design of a high-temperature experiment for evaluating advanced structural materials

NASA Technical Reports Server (NTRS)

Mockler, Theodore T.; Castro-Cedeno, Mario; Gladden, Herbert J.; Kaufman, Albert

1992-01-01

This report describes the design of an experiment for evaluating monolithic and composite material specimens in a high-temperature environment and subject to big thermal gradients. The material specimens will be exposed to aerothermal loads that correspond to thermally similar engine operating conditions. Materials evaluated in this study were monolithic nickel alloys and silicon carbide. In addition, composites such as tungsten/copper were evaluated. A facility to provide the test environment has been assembled in the Engine Research Building at the Lewis Research Center. The test section of the facility will permit both regular and Schlieren photography, thermal imaging, and laser Doppler anemometry. The test environment will be products of hydrogen-air combustion at temperatures from about 1200 F to as high as 4000 F. The test chamber pressure will vary up to 60 psia, and the free-stream flow velocity can reach Mach 0.9. The data collected will be used to validate thermal and stress analysis models of the specimen. This process of modeling, testing, and validation is expected to yield enhancements to existing analysis tools and techniques.

Cryogenic Moisture Uptake in Foam Insulation for Space Launch Vehicles

NASA Technical Reports Server (NTRS)

Fesmire, James E.; ScholtensCoffman, Brekke E.; Sass, Jared P.; Williams, Martha K.; Smith, Trent M.; Meneghelli, Barrry J.

2008-01-01

Rigid polyurethane foams and rigid polyisocyanurate foams (spray-on foam insulation), like those flown on Shuttle, Delta IV, and will be flown on Ares-I and Ares-V, can gain an extraordinary amount of water when under cryogenic conditions for several hours. These foams, when exposed for eight hours to launch pad environments on one side and cryogenic temperature on the other, increase their weight from 35 to 80 percent depending on the duration of weathering or aging. This effect translates into several thousand pounds of additional weight for space vehicles at lift-off. A new cryogenic moisture uptake apparatus was designed to determine the amount of water/ice taken into the specimen under actual-use propellant loading conditions. This experimental study included the measurement of the amount of moisture uptake within different foam materials. Results of testing using both aged specimens and weathered specimens are presented. To better understand cryogenic foam insulation performance, cryogenic moisture testing is shown to be essential. The implications for future launch vehicle thermal protection system design and flight performance are discussed.

Study of the lithology, petrology and rock chemistry for the Pyramid Mountains, New Mexico

NASA Technical Reports Server (NTRS)

Grant, S. K.

1985-01-01

Rock and soil samples were collected at 24 sites within the Pyramid Mountains of southwestern New Mexico. The site locations are specified as 10-acre plots within the Section, Township, and Range land survey system. Hand specimen are described. The specimen were analyzed by X-ray fluorescence. The technique is designed to obtain good analysis for silica. The other elements are run so that matrix factor logic can be used to adjust the silica intensities, and to compensate for the element interaction.

Design, fabrication, and implementation of thermally driven outdoor testing devices for building joint sealants.

PubMed

White, C C; Tan, K T; O'Brien, E P; Hunston, D L; Chin, J W; Williams, R S

2011-02-01

The paper describes the development, implementation, and testing of two thermally driven outdoor exposure instruments. These devices are unique in their ability to impose field generated thermally induced strain on sealant specimens while monitoring their resulting load and displacement. The instruments combine a fixed wood and steel supporting frame with a moving polyvinyl chloride frame, and employ differences in the coefficients of thermal expansion between the supporting frame and moving frame to induce strain on the sealant specimens. Two different kinds of instruments have been fabricated, "winter/tension" and "winter/compression" designs. In the winter/tension design, the thermally induced dimensional change is directly transferred to the specimens; while in the winter/compression design, the samples are loaded in an opposite direction with the dimensional change. Both designs are instrumented to monitor load and displacement and are built so that the strain on the specimen does not exceed ±25% over the range of temperatures expected in Gaithersburg, MD. Additionally, a weather station is colocated with the device to record environmental conditions in 1 min intervals. This combination of weather information with mechanical property data enables a direct link between environmental conditions and the corresponding sealant response. The reliability and effectiveness of these instruments are demonstrated with a typical sealant material. The results show that the instruments work according to the design criteria and provide a meaningful quantitative platform to monitor the mechanical response of sealant exposed to outdoor weathering.

Gram staining apparatus for space station applications

NASA Technical Reports Server (NTRS)

Molina, T. C.; Brown, H. D.; Irbe, R. M.; Pierson, D. L.

1990-01-01

A self-contained, portable Gram staining apparatus (GSA) has been developed for use in the microgravity environment on board the Space Station Freedom. Accuracy and reproducibility of this apparatus compared with the conventional Gram staining method were evaluated by using gram-negative and gram-positive controls and different species of bacteria grown in pure cultures. A subsequent study was designed to assess the performance of the GSA with actual specimens. A set of 60 human and environmental specimens was evaluated with the GSA and the conventional Gram staining procedure. Data obtained from these studies indicated that the GSA will provide the Gram staining capability needed for the microgravity environment of space.

A Novel Small-Specimen Planar Biaxial Testing System With Full In-Plane Deformation Control.

PubMed

Potter, Samuel; Graves, Jordan; Drach, Borys; Leahy, Thomas; Hammel, Chris; Feng, Yuan; Baker, Aaron; Sacks, Michael S

2018-05-01

Simulations of soft tissues require accurate and robust constitutive models, whose form is derived from carefully designed experimental studies. For such investigations of membranes or thin specimens, planar biaxial systems have been used extensively. Yet, all such systems remain limited in their ability to: (1) fully prescribe in-plane deformation gradient tensor F2D, (2) ensure homogeneity of the applied deformation, and (3) be able to accommodate sufficiently small specimens to ensure a reasonable degree of material homogeneity. To address these issues, we have developed a novel planar biaxial testing device that overcomes these difficulties and is capable of full control of the in-plane deformation gradient tensor F2D and of testing specimens as small as ∼4 mm × ∼4 mm. Individual actuation of the specimen attachment points, combined with a robust real-time feedback control, enabled the device to enforce any arbitrary F2D with a high degree of accuracy and homogeneity. Results from extensive device validation trials and example tissues illustrated the ability of the device to perform as designed and gather data needed for developing and validating constitutive models. Examples included the murine aortic tissues, allowing for investigators to take advantage of the genetic manipulation of murine disease models. These capabilities highlight the potential of the device to serve as a platform for informing and verifying the results of inverse models and for conducting robust, controlled investigation into the biomechanics of very local behaviors of soft tissues and membrane biomaterials.

Enclosed Cutting-And-Polishing Apparatus

NASA Technical Reports Server (NTRS)

Rossier, R. N.; Bicknell, B.

1989-01-01

Proposed apparatus cuts and polishes specimens while preventing contamination of outside environment or of subsequent specimens processed in it. Designed for use in zero gravity but also includes features useful in cutting and polishing of toxic or otherwise hazardous materials on Earth. Includes remote manipulator for handling specimens, cutting and polishing wire, inlets for gas and liquid, and outlets for waste liquid and gas. Replaceable plastic liner surrounds working space.

Distribution of Human papillomavirus load in clinical specimens.

PubMed

Lowe, Brian; O'Neil, Dominic; Loeffert, Dirk; Nazarenko, Irina

2011-04-01

The information about the range and distribution of Human papillomavirus load in clinical specimens is important for the design of accurate clinical tests. The amount of Human papillomavirus in cervical specimens was estimated using the digene HC2 HPV DNA Test(®) (QIAGEN). This semi-quantitative assay is based on linear signal amplification with an analytical limit-of-detection of approximately 2500 virus copies per assay and 3-4 log dynamic range. The dynamic range of the assay was extended by a serial dilution strategy. Two large sets of positive specimens (n=501 and 569) were analyzed and 9-11% of specimens was estimated to contain more than 7 × 10(7) copies of virus. The viral load was also assessed for an assortment of specimens with known cytology diagnoses (n=9435) and histological diagnoses (n=2056). The percentage of specimens with more than 7 × 10(7) copies of virus was estimated to be 0.89 for normal cells, 4.2 for atypical cells (unknown significance), 14.31 for cells of low-grade lesions and 22.24 for cells of high-grade lesions. The viral load increased with disease severity, but its broad distribution may not support its use as a disease biomarker. This information is important for assay design and automation, where cross-reactivity and sample-to-sample contamination must be addressed rigorously. Copyright © 2011 Elsevier B.V. All rights reserved.

Assembly and Delivery of Rabbit Capsules for Irradiation of Silicon Carbide Cladding Tube Specimens in the High Flux Isotope Reactor

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

Koyanagi, Takaaki; Petrie, Christian M.

Neutron irradiation of silicon carbide (SiC)-based fuel cladding under a high radial heat flux presents a critical challenge for SiC cladding concepts in light water reactors (LWRs). Fission heating in the fuel provides a high heat flux through the cladding, which, combined with the degraded thermal conductivity of SiC under irradiation, results in a large temperature gradient through the thickness of the cladding. The strong temperature dependence of swelling in SiC creates a complex stress profile in SiCbased cladding tubes as a result of differential swelling. The Nuclear Science User Facilities (NSUF) Program within the US Department of Energy Officemore » of Nuclear Energy is supporting research efforts to improve the scientific understanding of the effects of irradiation on SiC cladding tubes. Ultimately, the results of this project will provide experimental validation of multi-physics models for SiC-based fuel cladding during LWR operation. The first objective of this project is to irradiate tube specimens using a previously developed design that allows for irradiation testing of miniature SiC tube specimens subjected to a high radial heat flux. The previous “rabbit” capsule design uses the gamma heating in the core of the High Flux Isotope Reactor (HFIR) to drive a high heat flux through the cladding tube specimens. A compressible aluminum foil allows for a constant thermal contact conductance between the cladding tubes and the rabbit housing despite swelling of the SiC tubes. To allow separation of the effects of irradiation from those due to differential swelling under a high heat flux, a new design was developed under the NSUF program. This design allows for irradiation of similar SiC cladding tube specimens without a high radial heat flux. This report briefly describes the irradiation experiment design concepts, summarizes the irradiation test matrix, and reports on the successful delivery of six rabbit capsules to the HFIR. Rabbits of both low and high heat flux configurations have been assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. These rabbits contain a wide variety of specimens including monolith tubes, SiC fiber SiC matrix (SiC/SiC) composites, duplex specimens (inner composite, outer monolith), and specimens with a variety of metallic or ceramic coatings on the outer surface. The rabbits are targeted for insertion during HFIR cycle 475, which is scheduled for September 2017.« less

Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

PubMed

Tibesku, C O; Innocenti, B; Wong, P; Salehi, A; Labey, L

2012-02-01

Long-term success of contemporary total knee replacements relies to a large extent on proper implant alignment. This study was undertaken to test whether specimen-matched cutting blocks based on computed axial tomography (CT) scans could provide accurate rotational alignment of the femoral component. CT scans of five fresh frozen full leg cadaver specimens, equipped with infrared reflective markers, were used to produce a specimen-matched femoral cutting block. Using those blocks, the bone cuts were made to implant a bi-compartmental femoral component. Rotational alignment of the components in the horizontal plane was determined using an optical measurement system and compared with all relevant rotational reference axes identified on the CT scans. Average rotational alignment for the bi-compartmental component in the horizontal plane was 1.9° (range 0°-6.3°; standard deviation 2.6°). One specimen that showed the highest deviation from the planned alignment also featured a completely degraded medial articular surface. The CT-based specimen-matched cutting blocks achieved good rotational alignment accuracy except for one specimen with badly damaged cartilage. In such cases, imaging techniques that visualize the cartilage layer might be more suitable to design cutting blocks, as they will provide a better fit and increased surface support.

Next-Generation Sequencing of Aquatic Oligochaetes: Comparison of Experimental Communities

PubMed Central

Vivien, Régis; Lejzerowicz, Franck; Pawlowski, Jan

2016-01-01

Aquatic oligochaetes are a common group of freshwater benthic invertebrates known to be very sensitive to environmental changes and currently used as bioindicators in some countries. However, more extensive application of oligochaetes for assessing the ecological quality of sediments in watercourses and lakes would require overcoming the difficulties related to morphology-based identification of oligochaetes species. This study tested the Next-Generation Sequencing (NGS) of a standard cytochrome c oxydase I (COI) barcode as a tool for the rapid assessment of oligochaete diversity in environmental samples, based on mixed specimen samples. To know the composition of each sample we Sanger sequenced every specimen present in these samples. Our study showed that a large majority of OTUs (Operational Taxonomic Unit) could be detected by NGS analyses. We also observed congruence between the NGS and specimen abundance data for several but not all OTUs. Because the differences in sequence abundance data were consistent across samples, we exploited these variations to empirically design correction factors. We showed that such factors increased the congruence between the values of oligochaetes-based indices inferred from the NGS and the Sanger-sequenced specimen data. The validation of these correction factors by further experimental studies will be needed for the adaptation and use of NGS technology in biomonitoring studies based on oligochaete communities. PMID:26866802

Type specimens of Crotalus scutulatus (Chordata: Reptilia: Squamata: Viperidae) re-examined, with new evidence after more than a century of confusion

USGS Publications Warehouse

Cardwell, Michael D.; Gotte, Steve W.; McDiarmid, Roy W.; Gilmore, Ned; Poindexter, James A.

2013-01-01

The original description of Crotalus scutulatus (Chordata: Reptilia: Squamata: Viperidae) was published in 1861 by Robert Kennicott, who did not identify a type specimen or a type locality. We review the history of specimens purported to be the type(s) and various designations of type locality. We provide evidence that ANSP 7069 (formerly one of two specimens of USNM 5027) is the holotype and that the appropriate type locality is Fort Buchanan, near present-day Sonoita, in Santa Cruz County, Arizona.

Consideration of Wear Rates at High Velocity

DTIC Science & Technology

2010-03-01

specimen retracted back into the test slipper. The amount of wear was analyzed by comparing the pretest and posttest specimen thicknesses and weights...and Design System (DADS) Model . . . . . . . . . . . . . . . . . . . . . . . 62 3.1.2 January 2008 Test Mission Raw DADS Data . . 64 3.1.3 DADS...The experimental high-speed test track at Holloman Air Force Base (AFB) has undergone many design innovations over a span of fifty years. One of the

Post Flight Analysis of Optical Specimens from MISSE7

NASA Technical Reports Server (NTRS)

Stewart, Alan F.; Finckenor, Miria

2012-01-01

More than 100 optical specimens were flown on the MISSE7 platform. These included bare substrates in addition to coatings designed to exhibit clearly defined or enhanced sensitivity to the accumulation of contamination. Measurements were performed using spectrophotometers operating from the UV through the IR as well as ellipsometry. Results will be presented in addition to discussion of the best options for design of samples for future exposure experiments.

The type-material of Arctiinae (Lepidoptera, Erebidae) described by Burmeister and Berg in the collection of the Museo Argentino de Ciencias Naturales Bernardino Rivadavia (Buenos Aires, Argentina).

PubMed

Beccacece, Hernán M; Vincent, Benoit; Navarro, Fernando R

2014-01-01

Carlos G. Burmeister and Carlos Berg were among the most important and influential naturalists and zoologists in Argentina and South America and described 241 species and 34 genera of Lepidoptera. The Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN) housed some of the Lepidoptera type specimens of these authors. In this study we present a catalogue with complete information and photographs of 11 Burmeister type specimens and 10 Berg type specimens of Phaegopterina, Arctiina and Pericopina (Lepidoptera, Erebidae, Arctiinae, Arctiini) housed in the MACN. Lectotypes or holotypes were designated where primary type specimens could be recognized; in some cases we were not able to recognize types. The catalogue also proposes nomenclatural changes and new synonymies: Opharus picturata (Burmeister, 1878), comb. n.; Opharus brunnea Gaede, 1923: 7, syn. n.; Hypocrisias jonesi (Schaus, 1894), syn. n.; Leucanopsis infucata (Berg, 1882), stat. rev.; Paracles argentina (Berg, 1877), sp. rev.; Paracles uruguayensis (Berg, 1886), sp. rev.

A study of environmental characterization of conventional and advanced aluminum alloys for selection and design. Phase 2: The breaking load test method

NASA Technical Reports Server (NTRS)

Sprowls, D. O.; Bucci, R. J.; Ponchel, B. M.; Brazill, R. L.; Bretz, P. E.

1984-01-01

A technique is demonstrated for accelerated stress corrosion testing of high strength aluminum alloys. The method offers better precision and shorter exposure times than traditional pass fail procedures. The approach uses data from tension tests performed on replicate groups of smooth specimens after various lengths of exposure to static stress. The breaking strength measures degradation in the test specimen load carrying ability due to the environmental attack. Analysis of breaking load data by extreme value statistics enables the calculation of survival probabilities and a statistically defined threshold stress applicable to the specific test conditions. A fracture mechanics model is given which quantifies depth of attack in the stress corroded specimen by an effective flaw size calculated from the breaking stress and the material strength and fracture toughness properties. Comparisons are made with experimental results from three tempers of 7075 alloy plate tested by the breaking load method and by traditional tests of statistically loaded smooth tension bars and conventional precracked specimens.

The type-material of Arctiinae (Lepidoptera, Erebidae) described by Burmeister and Berg in the collection of the Museo Argentino de Ciencias Naturales Bernardino Rivadavia (Buenos Aires, Argentina)

PubMed Central

Beccacece, Hernán M.; Vincent, Benoit; Navarro, Fernando R.

2014-01-01

Abstract Carlos G. Burmeister and Carlos Berg were among the most important and influential naturalists and zoologists in Argentina and South America and described 241 species and 34 genera of Lepidoptera. The Museo Argentino de Ciencias Naturales Bernardino Rivadavia (MACN) housed some of the Lepidoptera type specimens of these authors. In this study we present a catalogue with complete information and photographs of 11 Burmeister type specimens and 10 Berg type specimens of Phaegopterina, Arctiina and Pericopina (Lepidoptera, Erebidae, Arctiinae, Arctiini) housed in the MACN. Lectotypes or holotypes were designated where primary type specimens could be recognized; in some cases we were not able to recognize types. The catalogue also proposes nomenclatural changes and new synonymies: Opharus picturata (Burmeister, 1878), comb. n.; Opharus brunnea Gaede, 1923: 7, syn. n.; Hypocrisias jonesi (Schaus, 1894), syn. n.; Leucanopsis infucata (Berg, 1882), stat. rev.; Paracles argentina (Berg, 1877), sp. rev.; Paracles uruguayensis (Berg, 1886), sp. rev. PMID:25061380

Acoustic fatigue and sound transmission characteristics of a ram composite panel design

NASA Technical Reports Server (NTRS)

Cockburn, J. A.; Chang, K. Y.; Kao, G. C.

1972-01-01

An experimental study to determine the acoustic fatigue characteristics of a flat multi-layered structural panel is described. The test panel represented a proposed design for the outer skin of a research application module to be housed within the space shuttle orbiter vehicle. The test specimen was mounted in one wall of the Wyle 100,000 cu ft reverberation room and exposed to a broadband acoustic environment having an overall level of 145 db. The test panel was exposed to nine separate applications of the acoustic environment, each application consisting of 250 seconds duration. Upon completion of the ninth test run, the specimen was exposed to a simulated micrometeoroid impact near the panel center. One additional test run of 250 seconds duration was then performed to complete the overall simulation of 50 flight missions. The experimental results show that no significant fatigue damage occurred until the test specimen was exposed to a simulated micrometeoroid impact. The intermediate foam layer forming the core of the test specimen suffered considerable damage due to this impact, causing a marked variation in the dynamic characteristics of the overall test panel. During the final application of the acoustic environment, the strain and acceleration response spectra showed considerable variation from those spectra obtained prior to impact of the panel. Fatigue damage from acoustic loading however, was limited to partial de-bonding around the edges of the composite panel.

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.

Development of Mix Design Method in Efforts to Increase Concrete Performance Using Portland Pozzolana Cement (PPC)

NASA Astrophysics Data System (ADS)

Krisnamurti; Soehardjono, A.; Zacoeb, A.; Wibowo, A.

2018-01-01

Earthquake disaster can cause infrastructure damage. Prevention of human casualties from disasters should do. Prevention efforts can do through improving the mechanical performance of building materials. To achieve high-performance concrete (HPC), usually used Ordinary Portland Cement (OPC). However, the most widely circulating cement types today are Portland Pozzolana Cement (PPC) or Portland Composite Cement (PCC). Therefore, the proportion of materials used in the HPC mix design needs to adjust to achieve the expected performance. This study aims to develop a concrete mix design method using PPC to fulfil the criteria of HPC. The study refers to the code/regulation of concrete mixtures that use OPC based on the results of laboratory testing. This research uses PPC material, gravel from Malang area, Lumajang sand, water, silica fume and superplasticizer of a polycarboxylate copolymer. The analyzed information includes the investigation results of aggregate properties, concrete mixed composition, water-binder ratio variation, specimen dimension, compressive strength and elasticity modulus of the specimen. The test results show that the concrete compressive strength achieves value between 25 MPa to 55 MPa. The mix design method that has developed can simplify the process of concrete mix design using PPC to achieve the certain desired performance of concrete.

Modeling and characterization of through-the-thickness properties of 3D woven composites

NASA Technical Reports Server (NTRS)

Hartranft, Dru; Pravizi-Majidi, Azar; Chou, Tsu-Wei

1995-01-01

The through-the-thickness properties of three-dimensionally (3D) woven carbon/epoxy composites have been studied. The investigation aimed at the evaluation and development of test methodologies for the property characterization in the thickness direction, and the establishment of fiber architectures were studied: layer-to-layer Angle Interlock, through-the-thickness Orthogonal woven preform with surface pile was also designed and manufactured for the fabrication of tensile test coupons with integrated grips. All the preforms were infiltrated by the resin transfer molding technique. The microstructures of the composites were characterized along the warp and fill (weft) directions to determine the degree of yarn undulations, yarn cross-sectional shapes, and microstructural dimensions. These parameters were correlated to the fiber architecture. Specimens were designed and tested for the direct measurement of the through-the-thickness tensile, compressive and shear properties of the composites. Design optimization was conducted through the analysis of the stress fields within the specimen coupled with experimental verification. The experimentally-derived elastic properties in the thickness direction compared well with analytical predictions obtained from a volume averaging model.

Thermal test of the insulation structure for LH 2 tank by using the large experimental apparatus

NASA Astrophysics Data System (ADS)

Kamiya, S.; Onishi, K.; Konshima, N.; Nishigaki, K.

Conceptual designs of large mass LH 2 (liquid hydrogen) storage systems, whose capacity is 50,000 m3, have been studied in the Japanese hydrogen project, World Energy Network (WE-NET) [K. Fukuda, in: WE-NET Hydrogen Energy Symposium, 1999, P1-P41]. This study has concluded that their thermal insulation structures for the huge LH 2 tanks should be developed. Their actual insulation structures comprise not only the insulation material but also reinforced members and joints. To evaluate their thermal performance correctly, a large test specimen including reinforced members and joints will be necessary. After verifying the thermal performance of a developed large experimental apparatus [S. Kamiya, Cryogenics 40 (1) (2000) 35] for measuring the thermal conductance of various insulation structures, we tested two specimens, a vacuum multilayer insulation (MLI) with a glass fiber reinforced plastic (GFRP) support and a vacuum solid insulation (microtherm ®) with joints. The thermal background test for verifying the thermal design of the experimental apparatus showed that the background heat leak is 0.1 W, small enough to satisfy apparatus performance requirement. The thermal conductance measurements of specimens also showed that thermal heat fluxes of MLI with a GFRP support and microtherm ® are 8 and 5.4 W/m2, respectively.

Investigating Delamination Migration in Composite Tape Laminates

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.; DeCarvalho, Nelson V.

2014-01-01

A modification to a recently developed test specimen designed to investigate migration of a delamination between neighboring ply interfaces in tape laminates is presented. The specimen is a cross-ply laminated beam consisting of 40 plies with a polytetrafluoroethylene insert spanning part way along its length. The insert is located between a lower 0-degree ply (specimen length direction) and a stack of four 90-degree plies (specimen width direction). The modification involved a stacking sequence that promotes stable delamination growth prior to migration, and included a relocation of the insert from the specimen midplane to the interface between plies 14 and 15. Specimens were clamped at both ends onto a rigid baseplate and loaded on their upper surface via a piano hinge assembly, resulting in a predominantly flexural loading condition. Tests were conducted with the load-application point positioned at various locations along a specimen's span. This position affected the sequence of damage events during a test.

The width-tapered double cantilever beam for interlaminar fracture testing

NASA Technical Reports Server (NTRS)

Bascom, W. D.; Jensen, R. M.; Bullman, G. W.; Hunston, D. L.

1984-01-01

The width-tapered double-cantilever-beam (WTDCB) specimen configuration used to determine the Mode-I interlaminar fracture energy (IFE) of composites has special advantages for routine development work and for quality-assurance purposes. These advantages come primarily from the simplicity of testing and the fact that the specimen is designed for constant change in compliance with crack length, so that the computation of Mode-I IFE is independent of crack length. In this paper, a simplified technique for fabrication and testing WTDCB specimens is described. Also presented are the effects of fiber orientation and specimen dimensions, a comparison of data obtained using the WTDCB specimens and other specimen geometries, and comparison of data obtained at different laboratories. It is concluded that the WTDCB gives interlaminar Mode-I IFE essentially equal to other type specimens, and that it can be used for rapid screening in resin-development work and for quality assurance of composite materials.

Rutting performance of cold bituminous emulsion mixtures

NASA Astrophysics Data System (ADS)

Arshad, Ahmad Kamil; Ali, Noor Azilatom; Shaffie, Ekarizan; Hashim, Wardati; Rahman, Zanariah Abd

2017-10-01

Cold Bituminous Emulsion Mixture (CBEM) is an environmentally friendly alternative to hot mix asphalt (HMA) for road surfacing, due to its low energy requirements. However, CBEM has generally been perceived to be less superior in performance, compared to HMA. This paper details a laboratory study on the rutting performance of CBEM. The main objective of this study is to determine the Marshall properties of CBEM and to evaluate the rutting performance. The effect of cement in CBEM was also evaluated in this study. The specimens were prepared using Marshall Mix Design Method and rutting performance was evaluated using the Asphalt Pavement Analyzer (APA). Marshall Properties were analysed to confirm compliance with the PWD Malaysia's specification requirements. The rutting performance for specimens with cement was also found to perform better than specimens without cement. It can be concluded that Cold Bituminous Emulsion Mixtures (CBEM) with cement is a viable alternative to Hot Mix Asphalt (HMA) as their Marshall Properties and performance obtained from this study meets the requirements of the specifications. It is recommended that further study be conducted on CBEM for other performance criteria such as moisture susceptibility and fatigue.

A simple cryo-holder facilitates specimen observation under a conventional scanning electron microscope.

PubMed

Tang, Chih-Yuan; Huang, Rong-Nan; Kuo-Huang, Ling-Long; Kuo, Tai-Chih; Yang, Ya-Yun; Lin, Ching-Yeh; Jane, Wann-Neng; Chen, Shiang-Jiuun

2012-02-01

A pre-cryogenic holder (cryo-holder) facilitating cryo-specimen observation under a conventional scanning electron microscope (SEM) is described. This cryo-holder includes a specimen-holding unit (the stub) and a cryogenic energy-storing unit (a composite of three cylinders assembled with a screw). After cooling, the cryo-holder can continue supplying cryogenic energy to extend the observation time for the specimen in a conventional SEM. Moreover, the cryogenic energy-storing unit could retain appropriate liquid nitrogen that can evaporate to prevent frost deposition on the surface of the specimen. This device is proved feasible for various tissues and cells, and can be applied to the fields of both biology and material science. We have employed this novel cryo-holder for observation of yeast cells, trichome, and epidermal cells in the leaf of Arabidopsis thaliana, compound eyes of insects, red blood cells, filiform papillae on the surface of rat tongue, agar medium, water molecules, penicillium, etc. All results suggested that the newly designed cryo-holder is applicable for cryo-specimen observation under a conventional SEM without cooling system. Most importantly, the design of this cryo-holder is simple and easy to operate and could adapt a conventional SEM to a plain type cryo-SEM affordable for most laboratories. Copyright © 2011 Wiley Periodicals, Inc.

Improved sensitivity of vaginal self-collection and high-risk human papillomavirus testing.

PubMed

Belinson, Jerome L; Du, Hui; Yang, Bin; Wu, Ruifang; Belinson, Suzanne E; Qu, Xinfeng; Pretorius, Robert G; Yi, Xin; Castle, Philip E

2012-04-15

Self-collected vaginal specimens tested for high-risk human papillomavirus (HR-HPV) have been shown to be less sensitive for the detection of cervical intraepithelial neoplasia or cancer (≥CIN 3) than physician-collected endocervical specimens. To increase the sensitivity of self-collected specimens, we studied a self-sampling device designed to obtain a larger specimen from the upper vagina (POI/NIH self-sampler) and a more sensitive polymerase chain reaction (PCR)-based HR-HPV assay. Women (10,000) were screened with cervical cytology and HR-HPV testing of vaginal self-collected and endocervical physician-collected specimens. Women were randomly assigned to use either a novel self-collection device (POI/NIH self-sampler) or conical-shaped brush (Qiagen). The self-collected and clinician-collected specimens were assayed by Cervista (Hologic) and the research only PCR-based matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF). Women with any abnormal screening test underwent colposcopy and biopsy. Women (8,556), mean age of 38.9, had complete data; 1.6% had ≥ CIN 3. For either HR-HPV assay, the sensitivity was similar for the two self-collection devices. Tested with Cervista, the sensitivity for ≥CIN 3 of self-collected specimens was 70.9% and for endocervical specimens was 95.0% (p = 0.0001). Tested with MALDI-TOF, the sensitivity for ≥CIN 3 of self-collected specimens was 94.3% and for endocervical specimens was also 94.3% (p = 1.0). A self-collected sample using a PCR-based assay with the capability of very high throughput has similar sensitivity as a direct endocervical specimen obtained by a physician. Large population-based screening "events" in low-resource settings could be achieved by promoting self-collection and centralized high-throughput, low-cost testing by PCR-based MALDI-TOF. Copyright © 2011 UICC.

A Comparison of the Flexural and Impact Strengths and Flexural Modulus of CAD/CAM and Conventional Heat-Cured Polymethyl Methacrylate (PMMA).

PubMed

Al-Dwairi, Ziad N; Tahboub, Kawkab Y; Baba, Nadim Z; Goodacre, Charles J

2018-06-13

The introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) technology to the field of removable prosthodontics has recently made it possible to fabricate complete dentures of prepolymerized polymethyl methacrylate (PMMA) blocks, which are claimed to be of better mechanical properties; however, no published reports that have evaluated mechanical properties of CAD/CAM PMMA. The purpose of this study was to compare flexural strength, impact strength, and flexural modulus of two brands of CAD/CAM PMMA and a conventional heat-cured PMMA. 45 rectangular specimens (65 mm × 10 mm × 3 mm) were fabricated (15 CAD/CAM AvaDent PMMA specimens from AvaDent, 15 CAD/CAM Tizian PMMA specimens from Shütz Dental, 15 conventional Meliodent PMMA specimens from Heraeus Kulzer) and stored in distilled water at (37  ± 1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on unnotched specimens. The morphology of the fractured specimens was studied under a scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey pairwise multiple comparisons with 95% confidence interval. The Schütz Dental specimens showed the highest mean flexural strength (130.67 MPa) and impact strength (29.56 kg/m 2 ). The highest mean flexural modulus was recorded in the AvaDent group (2519.6 MPa). The conventional heat-cured group showed the lowest mean flexural strength (93.33 MPa), impact strength (14.756 kg/m 2 ), and flexural modulus (2117.2 MPa). Differences in means of flexural properties between AvaDent and Schütz Dental specimens were not statistically significant (p > 0.05). As CAD/CAM PMMA specimens exhibited improved flexural strength, flexural modulus, and impact strength in comparison to the conventional heat-cured groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in mechanical properties. © 2018 by the American College of Prosthodontists.

Identification of Mycobacterium tuberculosis in Clinical Specimens of Patients Suspected of Having Extrapulmonary Tuberculosis by Application of Nested PCR on Five Different Genes

PubMed Central

Khosravi, Azar D.; Alami, Ameneh; Meghdadi, Hossein; Hosseini, Atta A.

2017-01-01

Definitive and rapid diagnosis of extrapulmonary tuberculosis (EPTB) is challenging since conventional techniques have limitations due to the paucibacillary nature of the disease. To increase the sensitivity of detection of Mycobacterium tuberculosis (MTB) in EPTB specimens, we performed a nested PCR assay targeting several genes of MTB on EPTB specimens. A total of 100 clinical specimens from suspected cases of EPTB were processed. Standard staining for acid fast bacilli (AFB) was performed as the preliminary screening test. Extracted DNAs from specimens were subjected to Nested PCR technique for the detection of five different MTB target genes of IS6110, IS1081, hsp65kd, mbp64, and mtp40. On performing AFB staining, only 13% of specimens were positive, of which ascites fluid (33.3%), followed by pleural effusion (30.8%) showed the greatest AFB positivity rate. We demonstrated slight improvement in yields in lymph node which comprised the majority of specimens in this study, by employing PCR targeted to IS6110- and hsp65-genes in comparison to AFB staining. However, the yields in ascites fluid and pleural effusion were not substantially improved by PCR, but those from bone and wound were, as in nested PCR employing either gene, the same positivity rate were obtained for ascites fluid (33.3%), while for pleural effusion specimens only IS1081 based PCR showed identical positivity rate with AFB stain (30.8%). The results for bone and wound specimens, however, demonstrated an improved yield mainly by employing IS1081 gene. Here, we report higher detection rate of EPTB in clinical specimens using five different targeted MTB genes. This nested PCR approach facilitates the comparison and the selection of the most frequently detected genes. Of course this study demonstrated the priority of IS1081 followed by mtp40 and IS6110, among the five tested genes and indicates the effectiveness of any of the three genes in the design of an efficient nested-PCR test that facilitates an early diagnosis of paucibacillary EPTB cases, which are difficult to diagnose with the available standard. PMID:28144587

Identification of Mycobacterium tuberculosis in Clinical Specimens of Patients Suspected of Having Extrapulmonary Tuberculosis by Application of Nested PCR on Five Different Genes.

PubMed

Khosravi, Azar D; Alami, Ameneh; Meghdadi, Hossein; Hosseini, Atta A

2017-01-01

Definitive and rapid diagnosis of extrapulmonary tuberculosis (EPTB) is challenging since conventional techniques have limitations due to the paucibacillary nature of the disease. To increase the sensitivity of detection of Mycobacterium tuberculosis (MTB) in EPTB specimens, we performed a nested PCR assay targeting several genes of MTB on EPTB specimens. A total of 100 clinical specimens from suspected cases of EPTB were processed. Standard staining for acid fast bacilli (AFB) was performed as the preliminary screening test. Extracted DNAs from specimens were subjected to Nested PCR technique for the detection of five different MTB target genes of IS6110, IS1081, hsp65kd, mbp64 , and mtp40 . On performing AFB staining, only 13% of specimens were positive, of which ascites fluid (33.3%), followed by pleural effusion (30.8%) showed the greatest AFB positivity rate. We demonstrated slight improvement in yields in lymph node which comprised the majority of specimens in this study, by employing PCR targeted to IS6110 - and hsp65-genes in comparison to AFB staining. However, the yields in ascites fluid and pleural effusion were not substantially improved by PCR, but those from bone and wound were, as in nested PCR employing either gene, the same positivity rate were obtained for ascites fluid (33.3%), while for pleural effusion specimens only IS1081 based PCR showed identical positivity rate with AFB stain (30.8%). The results for bone and wound specimens, however, demonstrated an improved yield mainly by employing IS1081 gene. Here, we report higher detection rate of EPTB in clinical specimens using five different targeted MTB genes. This nested PCR approach facilitates the comparison and the selection of the most frequently detected genes. Of course this study demonstrated the priority of IS1081 followed by mtp40 and IS6110 , among the five tested genes and indicates the effectiveness of any of the three genes in the design of an efficient nested-PCR test that facilitates an early diagnosis of paucibacillary EPTB cases, which are difficult to diagnose with the available standard.

Modernization of existing VVER-1000 surveillance programs

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

Kochkin, V.; Erak, D.; Makhotin, D.

2011-07-01

According to generally accepted world practice, evaluation of the reactor pressure vessel (RPV) material behavior during operation is carried out using tests of surveillance specimens. The main objective of the surveillance program consists in insurance of safe RPV operation during the design lifetime and lifetime-extension period. At present, the approaches of pressure vessels residual life validation based on the test results of their surveillance specimens have been developed and introduced in Russia and are under consideration in other countries where vodo-vodyanoi energetichesky reactors- (VVER-) 1000 are in operation. In this case, it is necessary to ensure leading irradiation of surveillancemore » specimens (as compared to the pressure vessel wall) and to provide uniformly irradiated specimen groups for mechanical testing. Standard surveillance program of VVER-1000 has several significant shortcomings and does not meet these requirements. Taking into account program of lifetime extension of VVER-1000 operating in Russia, it is necessary to carry out upgrading of the VVER-1000 surveillance program. This paper studies the conditions of a surveillance specimen's irradiation and upgrading of existing sets to provide monitoring and prognosis of RPV material properties for extension of the reactor's lifetime up to 60 years or more. (authors)« less

The Effect of Various Weave Designs on Mechanical Behavior of Lamina Intraply Composite Made from Kenaf Fiber Yarn

NASA Astrophysics Data System (ADS)

Yuhazri, M. Y.; Amirhafizan, M. H.; Abdullah, A.; Sihombing, H.; Saarah, A. B.; Fadzol, O. M.

2016-11-01

The development of lamina intraply composite is a novel approach that can be adopted to address the challenges of balance mechanical properties of polymer composite. This research will focuses on the effects of weave designs on the mechanical behavior of a single ply or also known as lamina intraply composite. The six (6) specimens of lamina intraply composites were made by kenaf fiber as a reinforcement and unsaturated polyester resin as a matrix in various weave designs which were plain, twill, satin, basket, mock leno and leno weave. The vacuum infusion technique was adopted due to advantages over hand lay-up. It was found that the plain, twill and satin weave exhibited better mechanical properties on tensile strength. The fiber content of the specimen was 40% and the result of the resin content of the specimen was 60% due to the higher permeability of natural fiber.

Liquid micrurgy chamber and microsyringe designs allow more efficient micromanipulations

NASA Technical Reports Server (NTRS)

Daniels, E. W.

1967-01-01

More efficient micromanipulations on large amoebae achieved by liquid micrurgy chamber and microsyringe. These innovations move the system closer to the specimen, and flatten the specimen for a clear view of the nuclei, also eliminating spherical abberation and evaporation.

Vestibular Function Research (VFR) experiment. Phase B: Design definition study

NASA Technical Reports Server (NTRS)

1978-01-01

The Vestibular Functions Research (VFR) Experiment was established to investigate the neurosensory and related physiological processes believed to be associated with the space flight nausea syndrome and to develop logical means for its prediction, prevention and treatment. The VFR Project consists of ground and spaceflight experimentation using frogs as specimens. The phase B Preliminary Design Study provided for the preliminary design of the experiment hardware, preparation of performance and hardware specification and a Phase C/D development plan, establishment of STS (Space Transportation System) interfaces and mission operations, and the study of a variety of hardware, experiment and mission options. The study consist of three major tasks: (1) mission mode trade-off; (2) conceptual design; and (3) preliminary design.

Creep rupture testing of carbon fiber-reinforced epoxy composites

NASA Astrophysics Data System (ADS)

Burton, Kathryn Anne

Carbon fiber is becoming more prevalent in everyday life. As such, it is necessary to have a thorough understanding of, not solely general mechanical properties, but of long-term material behavior. Creep rupture testing of carbon fiber is very difficult due to high strength and low strain to rupture properties. Past efforts have included testing upon strands, single tows and overwrapped pressure vessels. In this study, 1 inch wide, [0°/90°]s laminated composite specimens were constructed from fabric supplied by T.D. Williamson Inc. Specimen fabrication methods and gripping techniques were investigated and a method was developed to collect long term creep rupture behavior data. An Instron 1321 servo-hydraulic material testing machine was used to execute static strength and short term creep rupture tests. A hanging dead-weight apparatus was designed to perform long-term creep rupture testing. The testing apparatus, specimens, and specimen grips functioned well. Collected data exhibited a power law distribution and therefore, a linear trend upon a log strength-log time plot. Statistical analysis indicated the material exhibited slow degradation behavior, similar to previous studies, and could maintain a 50 year carrying capacity at 62% of static strength, approximately 45.7 ksi.

Development of a PCR Assay to Detect Low Level Trypanosoma cruzi in Blood Specimens Collected with PAXgene Blood DNA Tubes for Clinical Trials Treating Chagas Disease.

PubMed

Wei, Bo; Chen, Lei; Kibukawa, Miho; Kang, John; Waskin, Hetty; Marton, Matthew

2016-12-01

Chagas disease is caused by the parasitic infection of Trypanosoma cruzi (T. cruzi). The STOP CHAGAS clinical trial was initiated in 2011 to evaluate posaconazole in treating Chagas disease, with treatment success defined as negative qualitative PCR results of detecting the parasites in blood specimens collected post-treatment. PAXgene Blood DNA tubes were utilized as a simple procedure to collect and process blood specimens. However, the PAXgene blood specimens challenged published T. cruzi PCR methods, resulting in poor sensitivity and reproducibility. To accurately evaluate the treatment efficacy of the clinical study, we developed and validated a robust PCR assay for detecting low level T. cruzi in PAXgene blood specimens. The assay combines a new DNA extraction method with a custom designed qPCR assay, resulting in limit of detection of 0.005 and 0.01 fg/μl for K98 and CL Brener, two representative strains of two of T. cruzi's discrete typing units. Reliable qPCR standard curves were established for both strains to measure parasite loads, with amplification efficiency ≥ 90% and the lower limit of linearity ≥ 0.05 fg/μl. The assay successfully analyzed the samples collected from the STOP CHAGAS study and may prove useful for future global clinical trials evaluating new therapies for asymptomatic chronic Chagas disease.

Prevention of dental erosion of a sports drink by nano-sized hydroxyapatite in situ study.

PubMed

Min, Ji Hyun; Kwon, Ho Keun; Kim, Baek Il

2015-01-01

To evaluate the inhibitory effects of the sports drink containing nano-sized hydroxyapatite (nano-HA) on dental erosion in situ. The study had a single-blind, two-treatment crossover design. The two treatment groups were a control group (CG; Powerade only) and an experimental group (EG; 0.25% wt/vol nano-HA was added to Powerade). Ten subjects wore removable palatal appliances containing bovine enamel specimens. The appliances were immersed in each drink for 10 mins, 4 times a day for 10 days. The tooth surface microhardness (SMH) was tested, and the erosion depth and the morphology of the tooth surface were observed. The data were analysed by repeated measures anova and t-test. Between the baseline and the 10th day, SMH was decreased by 80% in the specimens of the CG (P < 0.001), whereas there was only a 6% decrease in the SMH of the specimens in the EG. An erosion depth of 12.70 ± 4.66 μm and an irregular tooth surface were observed on the 10th day in the specimens of the CG. No dental erosions, however, was observed in the specimens of the EG. The sports drink containing 0.25% nano-HA was effective in preventing dental erosion in situ. © 2014 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Failure probability of three designs of zirconia crowns

PubMed Central

Ramos, G. Freitas; Monteiro, E. Barbosa Carmona; Bottino, M.A.; Zhang, Y.; de Melo, R. Marques

2015-01-01

Objectives This study utilized a 2-parameter Weibull analysis for evaluation of lifetime of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. Methods Sixty first molars were selected and prepared for full-coverage crowns with three different designs(n = 20): Traditional –crowns with zirconia framework covered with feldspathic porcelain; Modified– crowns partially covered with veneering porcelain; and Monolithic–full-contour zirconia crowns. All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100N, 3Hz) with a piston with hemispherical tip (Ø=6 mm) until the specimens failed or up to 2×106 cycles. Every 500,000 cycles intervals, the fatigue tests were interrupted, and stereomicroscopy (10 X) was used to inspect the specimens for damage. We performed Weibull analysis of interval data to calculate the number of failures in each interval. Results The types and number of failures according to the groups were: cracking (Traditional-13, Modified-6) and chipping (Traditional-4) of the feldspathic porcelain, followed by delamination (Traditional-1) at the veneer/core interface and debonding (Monollithic-2) at the cementation interface. Weibull parameters (beta, scale; and eta, shape), with a two-sided confidence interval of 95%, were: Traditional – 1.25 and 0.9 × 106cycles; Modified– 0.58 and 11.7 × 106 cycles; and Monolithic – 1.05 and 16.5 × 106 cycles. Traditional crowns showed greater susceptibility to fatigue, the Modified group presented higher propensity to early failures, and the Monolithic group showed no susceptibility to fatigue. The Modified and Monolithic groups presented the highest number of crowns with no failures after the fatigue test. Conclusions The three crown designs presented significantly different behaviors under fatigue. The Modified and the Monolithic groups presented less probability to failure after 2×106cycles. PMID:26509988

Peeling behavior and spalling resistance of CFRP sheets bonded to bent concrete surfaces

NASA Astrophysics Data System (ADS)

Yuan, Hong; Li, Faping

2010-05-01

In this paper, the peeling behavior and the spalling resistance effect of carbon fiber reinforced polymer (CFRP) sheets externally bonded to bent concrete surfaces are firstly investigated experimentally. Twenty one curved specimens and seven plane specimens are studied in the paper, in which curved specimens with bonded CFRP sheets can simulate the concrete spalling in tunnel, culvert, arch bridge etc., whereas plane specimens with bonded CFRP sheets can simulate the concrete spalling in beam bridge, slab bridge and pedestrian bridge. Three kinds of curved specimens with different radii of curvature are chosen by referring to practical tunnel structures, and plane specimens are used for comparison with curved ones. A peeling load is applied on the FRP sheet by loading a circular steel tube placed into the central notch of beam to debond CFRP sheets from the bent concrete surface, meanwhile full-range load-deflection curves are recorded by a MTS 831.10 Elastomer Test System. Based on the experimental results, a theoretical analysis is also conducted for the specimens. Both theoretical and experimental results show that only two material parameters, the interfacial fracture energy of CFRP-concrete interface and the tensile stiffness of CFRP sheets, are needed for describing the interfacial spalling behavior. It is found that the radius of curvature has remarkable influence on peeling load-deflection curves. The test methods and test results given in the paper are helpful and available for reference to the designer of tunnel strengthening.

Crush testing, characterizing, and modeling the crashworthiness of composite laminates

NASA Astrophysics Data System (ADS)

Garner, David Michael, Jr.

Research in the field of crashworthiness of composite materials is presented. A new crush test method was produced to characterize the crush behavior of composite laminates. In addition, a model of the crush behavior and a method for rank ordering the energy absorption capability of various laminates were developed. The new crush test method was used for evaluating the crush behavior of flat carbon/epoxy composite specimens at quasi-static and dynamic rates. The University of Utah crush test fixture was designed to support the flat specimen against catastrophic buckling. A gap, where the specimen is unsupported, allowed unhindered crushing of the specimen. In addition, the specimen's failure modes could be clearly observed during crush testing. Extensive crush testing was conducted wherein the crush force and displacement data were collected to calculate the energy absorption, and high speed video was captured during dynamic testing. Crush tests were also performed over a range of fixture gap heights. The basic failure modes were buckling, crack growth, and fracture. Gap height variations resulted in poorly, properly, and overly constrained specimens. In addition, guidelines for designing a composite laminate for crashworthiness were developed. Modeling of the crush behavior consisted of the delamination and fracture of a single ply or group of like plies during crushing. Delamination crack extension was modeled using the mode I energy release rate, G lc, where an elastica approach was used to obtain the strain energy. Variations in Glc were briefly explored with double cantilever beam tests wherein crack extension occurred along a multidirectional ply interface. The model correctly predicted the failure modes for most of the test cases, and offered insight into how the input parameters affect the model. The ranking method related coefficients of the laminate and sublaminate stiffness matrices, the ply locations within the laminate, and the laminate thickness. The ranking method correctly ordered the laminates tested in this study with respect to their energy absorption.

Laser assisted soldering: microdroplet accumulation with a microjet device.

PubMed

Chan, E K; Lu, Q; Bell, B; Motamedi, M; Frederickson, C; Brown, D T; Kovach, I S; Welch, A J

1998-01-01

We investigated the feasibility of a microjet to dispense protein solder for laser assisted soldering. Successive micro solder droplets were deposited on rat dermis and bovine intima specimens. Fixed laser exposure was synchronized with the jetting of each droplet. After photocoagulation, each specimen was cut into two halves at the center of solder coagulum. One half was fixed immediately, while the other half was soaked in phosphate-buffered saline for a designated hydration period before fixation (1 hour, 1, 2, and 7 days). After each hydration period, all tissue specimens were prepared for scanning electron microscopy (SEM). Stable solder coagulum was created by successive photocoagulation of microdroplets even after the soldered tissue exposed to 1 week of hydration. This preliminary study suggested that tissue soldering with successive microdroplets is feasible even with fixed laser parameters without active feedback control.

Biomedical Experiments Scientific Satellite /BESS/

NASA Technical Reports Server (NTRS)

Berry, W. E.; Tremor, J. W.; Aepli, T. C.

1976-01-01

The Biomedical Experiments Scientific Satellite (BESS) program is proposed to provide a long-duration, earth-orbiting facility to expose selected specimens in a series of biomedical experiments through the 1980's. Launched and retrieved by the Space Transportation System, the fully reusable, free-flying BESS will contain all systems necessary to conduct a six-month to one-year spaceflight mission. The spacecraft system will consist of a large pressurized experiment module and a standard NASA service module currently conceived as the Goddard Multi-Mission Spacecraft (MMS). The experiment module will contain the life-support systems, waste management system, specimen-holding facilities, and monitoring, evaluating, and data-handling equipment. Although a variety of specimens will be flown in basic biological and medical studies, the primate was taken as the principal design driver since it has a maximal life-support demand.

Column strength of tubes elastically restrained against rotation at the ends

NASA Technical Reports Server (NTRS)

Osgood, William R

1938-01-01

Report presents the results of a study made of the effects of known end restraint on commercially available round and streamline tubing of chromium-molybdenum steel, duralumin, stainless steel, and heat-treated chromium-molybdenum steel; and a more accurate method than any previously available, but still a practical method, was developed for designing compression members in riveted or welded structures, particularly aircraft. Two hundred specimens were tested as short, medium-length, and long columns with freely supported ends or elastically restrained ends. Tensile and compressive tests were made on each piece of original tubing from which column specimens were cut.

Performance of lap splices in large-scale column specimens affected by ASR and/or DEF.

DOT National Transportation Integrated Search

2012-06-01

This research program conducted a large experimental program, which consisted of the design, construction, : curing, deterioration, and structural load testing of 16 large-scale column specimens with a critical lap splice : region, and then compared ...

Specimen Design for Sustained Load Testing of Parallel-Laid Glass Fibre Reinforced Plastics.

DTIC Science & Technology

prepared by molding on a sheet of woven glass fabric and stripping this off just before bonding, to leave a roughened surface. The test specimens are 1/2 inch wide strips cut from the laminates. (Author, modified-PL)

Effects of a 3D segmental prosthetic system for tricuspid valve annulus remodelling on the right coronary artery: a human cadaveric coronary angiography study.

PubMed

Riki-Marishani, Mohsen; Gholoobi, Arash; Sazegar, Ghasem; Aazami, Mathias H; Hedjazi, Aria; Sajjadian, Maryam; Ebrahimi, Mahmoud; Aghaii-Zade Torabi, Ahmad

2017-09-01

A prosthetic system to repair secondary tricuspid valve regurgitation was developed. The conceptual engineering of the current device is based on 3D segmental remodelling of the tricuspid valve annulus in lieu of reductive annuloplasty. This study was designed to investigate the operational safety of the current prosthetic system with regard to the anatomical integrity of the right coronary artery (RCA) in fresh cadaveric human hearts. During the study period, from January to April 2016, the current prosthetic system was implanted on the tricuspid valve annulus in fresh cadaveric human hearts that met the study's inclusion criteria. The prepared specimens were investigated via selective coronary angiography of the RCA in the catheterization laboratory. The RCA angiographic anatomies were categorized as normal, distorted, kinked or occluded. Sixteen specimens underwent implantation of the current prosthetic system. The mean age of the cadaveric human hearts was 43.24 ± 15.79 years, with vehicle accident being the primary cause of death (59%). A dominant RCA was noticed in 62.5% of the specimens. None of the specimens displayed any injury, distortion, kinking or occlusion in the RCA due to the implantation of the prostheses. In light of the results of the present study, undertaken on fresh cadaveric human heart specimens, the current segmental prosthetic system for 3D remodelling of the tricuspid valve annulus seems to be safe vis-à-vis the anatomical integrity of the RCA. Further in vivo studies are needed to investigate the functional features of the current prosthetic system with a view to addressing the complex pathophysiology of secondary tricuspid valve regurgitation. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Field evaluation of a new light trap for phlebotomine sand flies.

PubMed

Gaglio, Gabriella; Napoli, Ettore; Falsone, Luigi; Giannetto, Salvatore; Brianti, Emanuele

2017-10-01

Light traps are one of the most common attractive method for the collection of nocturnal insects. Although light traps are generally referred to as "CDC light traps", different models, equipped with incandescent or UV lamps, have been developed. A new light trap, named Laika trap 3.0, equipped with LED lamps and featured with a light and handy design, has been recently proposed into the market. In this study we tested and compared the capture performances of this new trap with those of a classical light trap model under field conditions. From May to November 2013, a Laika trap and a classical light trap were placed biweekly in an area endemic for sand flies. A total of 256 sand fly specimens, belonging to 3 species (Sergentomyia minuta, Phlebotomus perniciosus, Phlebotomus neglectus) were collected during the study period. The Laika trap captured 126 phlebotomine sand flies: P. perniciosus (n=38); S. minuta (n=88), a similar number of specimens (130) and the same species were captured by classical light trap which collected also 3 specimens of P. neglectus. No significant differences in the capture efficiency at each day of trapping, neither in the number of species or in the sex of sand flies were observed. According to results of this study, the Laika trap may be a valid alternative to classical light trap models especially when handy design and low power consumption are key factors in field studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Microfabricated instrument for tissue biopsy and analysis

DOEpatents

Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

2001-01-01

A microfabricated biopsy/histology instrument which has several advantages over the conventional procedures, including minimal specimen handling, smooth cutting edges with atomic sharpness capable of slicing very thin specimens (approximately 2 .mu.m or greater), micro-liter volumes of chemicals for treating the specimens, low cost, disposable, fabrication process which renders sterile parts, and ease of use. The cutter is a "cheese-grater" style design comprising a block or substrate of silicon and which uses anisotropic etching of the silicon to form extremely sharp and precise cutting edges. As a specimen is cut, it passes through the silicon cutter and lies flat on a piece of glass which is bonded to the cutter. Microchannels are etched into the glass or silicon substrates for delivering small volumes of chemicals for treating the specimen. After treatment, the specimens can be examined through the glass substrate.

Measurement of damping of graphite epoxy materials

NASA Technical Reports Server (NTRS)

Crocker, M. J.

1985-01-01

The design of an experiment to measure the damping of a cylindrical graphite-epoxy specimen with a three point support and a knife edge support is described as well as equipment used in tests conducted to determine the influence of the support at the two ends of the specimen and to simulate an idealized free-free boundary condition at the two edges. A curve fitting technique is being used to process the frequency response data obtained. Experiments conducted on the thin plate specimen also reveal the influence of the end support condition on the damping ratio of the specimen. The damping ratio values measured for both specimens appear to be strongly influenced by the shape of the specimen and appear to depend on length and fiber orientation as well as the presence of discontinuities such as sharp bends, corners, and notches.

An experimental study on the shear strength of FRP perfobond shear connector

NASA Astrophysics Data System (ADS)

Gwon, S. C.; Kim, S. H.; Yoon, S. J.; Choi, C. W.

2018-06-01

In this study, push-out tests were conducted to investigate shear behaviour of FRP perfobond shear connector. The parameters influencing shear capacity of FRP perfobond shear connector are concrete dowel effect, shear resistance effect of the laterally reinforced FRP re- bar, and frictional effect between shear connector and concrete. The specimens were designed to consider these parameters. The specimens coated with sand to increase frictional resistance between the FRP re-bar and concrete. Based on the test results and the parameters, new equation was suggested to predict shear strength of FRP perfobond shear connectors. The predicted results and the experimental results were compared to check the feasibility of prediction.

Gram staining apparatus for space station applications.

PubMed Central

Molina, T C; Brown, H D; Irbe, R M; Pierson, D L

1990-01-01

A self-contained, portable Gram staining apparatus (GSA) has been developed for use in the microgravity environment on board the Space Station Freedom. Accuracy and reproducibility of this apparatus compared with the conventional Gram staining method were evaluated by using gram-negative and gram-positive controls and different species of bacteria grown in pure cultures. A subsequent study was designed to assess the performance of the GSA with actual specimens. A set of 60 human and environmental specimens was evaluated with the GSA and the conventional Gram staining procedure. Data obtained from these studies indicated that the GSA will provide the Gram staining capability needed for the microgravity environment of space. Images PMID:1690529

Weight versus volume in breast surgery: an observational study

PubMed Central

Parmar, Chetan; West, Malcolm; Pathak, Samir; Nelson, J; Martin, Lee

2011-01-01

Objectives The study hypothesis is to assess correlation of breast specimen weight versus volume. Design Consecutive patients undergoing breast surgery at a single tertiary referral centre during a 6-month period were included. Specimen weight was measured in grams. Direct volume measurements were performed using water displacement. Data including side of the breast, age and menstrual status of the patient were noted. Setting Knowledge of breast volume provides an objective guide in facilitating the achievements of balance in reconstructive operations. Surgeons use intraoperative weight measurements from individual breasts to calculate the breast volume assuming that weight is equal to the volume of the specimen. However, it is unclear whether weight accurately reveals the true volume of resection. Participants Forty-one patients were included in the study with 28 having bilateral surgeries, 13 having unilateral procedures giving a total of 69 breast specimens. Main outcome measures Breast specimen weight correlation to breast specimen volume. Results The mean age of the group was 42.4 years. Fifty-two specimens were from premenopausal patients and 17 were of postmenopausal. Thirty-five were left-sided. Twenty-six patients had bilateral breast reduction, two had bilateral mastectomy, nine had a unilateral mastectomy and four patients had a unilateral breast reduction. The difference between weight and volume of these breasts was 36.4 units (6.6% difference). The difference in measurement of weight and volume in premenopausal was 37.6 units compared to 32.6 units in postmenopausal women. The density was 1.07 and 1.06, respectively. This was statistically not significant. Conclusions No significant difference between volume and weight was seen in this series. Furthermore, we are unable to support the notion that premenopausal patients have a significant difference in the proportion of fatty and glandular tissue as there was little difference between the weight and the volume. An easy, clinically proper formula for the quantification of actual breast volume has yet to be derived. PMID:22140613

Design concepts for the Centrifuge Facility Life Sciences Glovebox

NASA Technical Reports Server (NTRS)

Sun, Sidney C.; Horkachuck, Michael J.; Mckeown, Kellie A.

1989-01-01

The Life Sciences Glovebox will provide the bioisolated environment to support on-orbit operations involving non-human live specimens and samples for human life sceinces experiments. It will be part of the Centrifuge Facility, in which animal and plant specimens are housed in bioisolated Habitat modules and transported to the Glovebox as part of the experiment protocols supported by the crew. At the Glovebox, up to two crew members and two habitat modules must be accommodated to provide flexibility and support optimal operations. This paper will present several innovative design concepts that attempt to satisfy the basic Glovebox requirements. These concepts were evaluated for ergonomics and ease of operations using computer modeling and full-scale mockups. The more promising ideas were presented to scientists and astronauts for their evaluation. Their comments, and the results from other evaluations are presented. Based on the evaluations, the authors recommend designs and features that will help optimize crew performance and facilitate science accommodations, and specify problem areas that require further study.

Patient-specific core decompression surgery for early-stage ischemic necrosis of the femoral head

PubMed Central

Wang, Wei; Hu, Wei; Yang, Pei; Dang, Xiao Qian; Li, Xiao Hui; Wang, Kun Zheng

2017-01-01

Introduction Core decompression is an efficient treatment for early stage ischemic necrosis of the femoral head. In conventional procedures, the pre-operative X-ray only shows one plane of the ischemic area, which often results in inaccurate drilling. This paper introduces a new method that uses computer-assisted technology and rapid prototyping to enhance drilling accuracy during core decompression surgeries and presents a validation study of cadaveric tests. Methods Twelve cadaveric human femurs were used to simulate early-stage ischemic necrosis. The core decompression target at the anterolateral femoral head was simulated using an embedded glass ball (target). Three positioning Kirschner wires were drilled into the top and bottom of the large rotor. The specimen was then subjected to computed tomography (CT). A CT image of the specimen was imported into the Mimics software to construct a three-dimensional model including the target. The best core decompression channel was then designed using the 3D model. A navigational template for the specimen was designed using the Pro/E software and manufactured by rapid prototyping technology to guide the drilling channel. The specimen-specific navigation template was installed on the specimen using positioning Kirschner wires. Drilling was performed using a guide needle through the guiding hole on the templates. The distance between the end point of the guide needle and the target was measured to validate the patient-specific surgical accuracy. Results The average distance between the tip of the guide needle drilled through the guiding template and the target was 1.92±0.071 mm. Conclusions Core decompression using a computer-rapid prototyping template is a reliable and accurate technique that could provide a new method of precision decompression for early-stage ischemic necrosis. PMID:28464029

Patient-specific core decompression surgery for early-stage ischemic necrosis of the femoral head.

PubMed

Wang, Wei; Hu, Wei; Yang, Pei; Dang, Xiao Qian; Li, Xiao Hui; Wang, Kun Zheng

2017-01-01

Core decompression is an efficient treatment for early stage ischemic necrosis of the femoral head. In conventional procedures, the pre-operative X-ray only shows one plane of the ischemic area, which often results in inaccurate drilling. This paper introduces a new method that uses computer-assisted technology and rapid prototyping to enhance drilling accuracy during core decompression surgeries and presents a validation study of cadaveric tests. Twelve cadaveric human femurs were used to simulate early-stage ischemic necrosis. The core decompression target at the anterolateral femoral head was simulated using an embedded glass ball (target). Three positioning Kirschner wires were drilled into the top and bottom of the large rotor. The specimen was then subjected to computed tomography (CT). A CT image of the specimen was imported into the Mimics software to construct a three-dimensional model including the target. The best core decompression channel was then designed using the 3D model. A navigational template for the specimen was designed using the Pro/E software and manufactured by rapid prototyping technology to guide the drilling channel. The specimen-specific navigation template was installed on the specimen using positioning Kirschner wires. Drilling was performed using a guide needle through the guiding hole on the templates. The distance between the end point of the guide needle and the target was measured to validate the patient-specific surgical accuracy. The average distance between the tip of the guide needle drilled through the guiding template and the target was 1.92±0.071 mm. Core decompression using a computer-rapid prototyping template is a reliable and accurate technique that could provide a new method of precision decompression for early-stage ischemic necrosis.

Bacterial Colonization and Tissue Compatibility of Denture Base Resins.

PubMed

Olms, Constanze; Yahiaoui-Doktor, Maryam; Remmerbach, Torsten W; Stingu, Catalina Suzana

2018-06-15

Currently, there is minimal clinical data regarding biofilm composition on the surface of denture bases and the clinical tissue compatibility. Therefore, the aim of this experimental study was to compare the bacterial colonization and the tissue compatibility of a hypoallergenic polyamide with a frequently used PMMA resin tested intraorally in a randomized split-mouth design. Test specimens made of polyamide ( n = 10) and PMMA ( n = 10) were attached over a molar band appliance in oral cavity of 10 subjects. A cytological smear test was done from palatal mucosa at baseline and after four weeks. The monolayers were inspected for micronuclei. After four weeks in situ, the appliance was removed. The test specimens were immediately cultivated on non-selective and selective nutrient media. All growing colonies were identified using VITEK-MS. The anonymized results were analyzed descriptively. A total of 110 different bacterial species could be isolated, including putative pathogens. An average of 17.8 different bacterial species grew on the PMMA specimens, and 17.3 on the polyamide specimens. The highest number of different bacterial species was n = 24, found on a PMMA specimen. On the two specimens, a similar bacterial distribution was observed. Micronuclei, as a marker for genotoxic potential of dental materials, were not detected. This study indicates that the composition of bacterial biofilm developed on these resins after four weeks is not influenced by the type of resin itself. The two materials showed no cytological differences. This investigation suggests that polyamide and PMMA are suitable for clinical use as denture base material.

Designs for a quantum electron microscope.

PubMed

Kruit, P; Hobbs, R G; Kim, C-S; Yang, Y; Manfrinato, V R; Hammer, J; Thomas, S; Weber, P; Klopfer, B; Kohstall, C; Juffmann, T; Kasevich, M A; Hommelhoff, P; Berggren, K K

2016-05-01

One of the astounding consequences of quantum mechanics is that it allows the detection of a target using an incident probe, with only a low probability of interaction of the probe and the target. This 'quantum weirdness' could be applied in the field of electron microscopy to generate images of beam-sensitive specimens with substantially reduced damage to the specimen. A reduction of beam-induced damage to specimens is especially of great importance if it can enable imaging of biological specimens with atomic resolution. Following a recent suggestion that interaction-free measurements are possible with electrons, we now analyze the difficulties of actually building an atomic resolution interaction-free electron microscope, or "quantum electron microscope". A quantum electron microscope would require a number of unique components not found in conventional transmission electron microscopes. These components include a coherent electron beam-splitter or two-state-coupler, and a resonator structure to allow each electron to interrogate the specimen multiple times, thus supporting high success probabilities for interaction-free detection of the specimen. Different system designs are presented here, which are based on four different choices of two-state-couplers: a thin crystal, a grating mirror, a standing light wave and an electro-dynamical pseudopotential. Challenges for the detailed electron optical design are identified as future directions for development. While it is concluded that it should be possible to build an atomic resolution quantum electron microscope, we have also identified a number of hurdles to the development of such a microscope and further theoretical investigations that will be required to enable a complete interpretation of the images produced by such a microscope. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Analysis and seismic tests of composite shear walls with CFST columns and steel plate deep beams

NASA Astrophysics Data System (ADS)

Dong, Hongying; Cao, Wanlin; Wu, Haipeng; Zhang, Jianwei; Xu, Fangfang

2013-12-01

A composite shear wall concept based on concrete filled steel tube (CFST) columns and steel plate (SP) deep beams is proposed and examined in this study. The new wall is composed of three different energy dissipation elements: CFST columns; SP deep beams; and reinforced concrete (RC) strips. The RC strips are intended to allow the core structural elements — the CFST columns and SP deep beams — to work as a single structure to consume energy. Six specimens of different configurations were tested under cyclic loading. The resulting data are analyzed herein. In addition, numerical simulations of the stress and damage processes for each specimen were carried out, and simulations were completed for a range of location and span-height ratio variations for the SP beams. The simulations show good agreement with the test results. The core structure exhibits a ductile yielding mechanism characteristic of strong column-weak beam structures, hysteretic curves are plump and the composite shear wall exhibits several seismic defense lines. The deformation of the shear wall specimens with encased CFST column and SP deep beam design appears to be closer to that of entire shear walls. Establishing optimal design parameters for the configuration of SP deep beams is pivotal to the best seismic behavior of the wall. The new composite shear wall is therefore suitable for use in the seismic design of building structures.

Ternary Magnesium-Lithium Base Constitution Diagrams and Magnesium Alloys of Low Alloy Additions

DTIC Science & Technology

1951-03-01

progress In eperimental development of mgmesiu-bease &alls with low alloy additions. The primry purpose of this investiptiU is to obtain alloys baving a...Casting Magnesium-Lithium Base Ternary Alloys Melting and Castirg Technigue The design , construction and operation of equipment for melting and...protection during heat treatment were: 1. Design and construction of a specimen container to hold a number of specimens in an inert atmosphere in order to WAC

Investigation of Weibull statistics in fracture analysis of cast aluminum

NASA Technical Reports Server (NTRS)

Holland, Frederic A., Jr.; Zaretsky, Erwin V.

1989-01-01

The fracture strengths of two large batches of A357-T6 cast aluminum coupon specimens were compared by using two-parameter Weibull analysis. The minimum number of these specimens necessary to find the fracture strength of the material was determined. The applicability of three-parameter Weibull analysis was also investigated. A design methodology based on the combination of elementary stress analysis and Weibull statistical analysis is advanced and applied to the design of a spherical pressure vessel shell. The results from this design methodology are compared with results from the applicable ASME pressure vessel code.

Sequencing historical specimens: successful preparation of small specimens with low amounts of degraded DNA.

PubMed

Sproul, John S; Maddison, David R

2017-11-01

Despite advances that allow DNA sequencing of old museum specimens, sequencing small-bodied, historical specimens can be challenging and unreliable as many contain only small amounts of fragmented DNA. Dependable methods to sequence such specimens are especially critical if the specimens are unique. We attempt to sequence small-bodied (3-6 mm) historical specimens (including nomenclatural types) of beetles that have been housed, dried, in museums for 58-159 years, and for which few or no suitable replacement specimens exist. To better understand ideal approaches of sample preparation and produce preparation guidelines, we compared different library preparation protocols using low amounts of input DNA (1-10 ng). We also explored low-cost optimizations designed to improve library preparation efficiency and sequencing success of historical specimens with minimal DNA, such as enzymatic repair of DNA. We report successful sample preparation and sequencing for all historical specimens despite our low-input DNA approach. We provide a list of guidelines related to DNA repair, bead handling, reducing adapter dimers and library amplification. We present these guidelines to facilitate more economical use of valuable DNA and enable more consistent results in projects that aim to sequence challenging, irreplaceable historical specimens. © 2017 John Wiley & Sons Ltd.

A simple-shear rheometer for linear viscoelastic characterization of vocal fold tissues at phonatory frequencies.

PubMed

Chan, Roger W; Rodriguez, Maritza L

2008-08-01

Previous studies reporting the linear viscoelastic shear properties of the human vocal fold cover or mucosa have been based on torsional rheometry, with measurements limited to low audio frequencies, up to around 80 Hz. This paper describes the design and validation of a custom-built, controlled-strain, linear, simple-shear rheometer system capable of direct empirical measurements of viscoelastic shear properties at phonatory frequencies. A tissue specimen was subjected to simple shear between two parallel, rigid acrylic plates, with a linear motor creating a translational sinusoidal displacement of the specimen via the upper plate, and the lower plate transmitting the harmonic shear force resulting from the viscoelastic response of the specimen. The displacement of the specimen was measured by a linear variable differential transformer whereas the shear force was detected by a piezoelectric transducer. The frequency response characteristics of these system components were assessed by vibration experiments with accelerometers. Measurements of the viscoelastic shear moduli (G' and G") of a standard ANSI S2.21 polyurethane material and those of human vocal fold cover specimens were made, along with estimation of the system signal and noise levels. Preliminary results showed that the rheometer can provide valid and reliable rheometric data of vocal fold lamina propria specimens at frequencies of up to around 250 Hz, well into the phonatory range.

Thick Concrete Specimen Construction, Testing, and Preliminary Analysis

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

Clayton, Dwight A.; Hoegh, Kyle; Khazanovich, Lev

The purpose of the U.S. Department of Energy Office of Nuclear Energy’s Light Water Reactor Sustainability (LWRS) Program is to develop technologies and other solutions that can improve the reliability, sustain the safety, and extend the operating lifetimes of nuclear power plants (NPPs) beyond 60 years. Since many important safety structures in an NPP are constructed of concrete, inspection techniques must be developed and tested to evaluate the internal condition. In-service containment structures generally do not allow for the destructive measures necessary to validate the accuracy of these inspection techniques. This creates a need for comparative testing of the variousmore » nondestructive evaluation (NDE) measurement techniques on concrete specimens with known material properties, voids, internal microstructure flaws, and reinforcement locations. A preliminary report detailed some of the challenges associated with thick reinforced concrete sections and prioritized conceptual designs of specimens that could be fabricated to represent NPP concrete structures for using in NDE evaluation comparisons. This led to the construction of the concrete specimen presented in this report, which has sufficient reinforcement density and cross-sectional size to represent an NPP containment wall. Details on how a suitably thick concrete specimen was constructed are presented, including the construction materials, final nominal design schematic, as well as formwork and rigging required to safely meet the desired dimensions of the concrete structure. The report also details the type and methods of forming the concrete specimen as well as information on how the rebar and simulated defects were embedded. Details on how the resulting specimen was transported, safely anchored, and marked to allow access for systematic comparative NDE testing of defects in a representative NPP containment wall concrete specimen are also given. Data collection using the MIRA Ultrasonic NDE equipment and initial results are also presented along with a discussion of the preliminary findings. Comparative NDE of various defects in reinforced concrete specimens is a key component in identifying the most promising techniques and directing the research and development efforts needed to characterize concrete degradation in commercial NPPs. This requires access to the specimens for data collection using state-of-the-art technology. The construction of the specimen detailed in this report allows for an evaluation of how different NDE techniques may interact with the size and complexities of NPP concrete structures. These factors were taken into account when determining specimen size and features to ensure a realistic design. The lateral dimensions of the specimen were also chosen to mitigate unrealistic boundary effects that would not affect the results of field NPP concrete testing. Preliminary results show that, while the current methods are able to identify some of the deeper defects, improvements in data processing or hardware are necessary to be able to achieve the precision and reliability achieved in evaluating thinner and less heavily reinforced concrete structures.« less

Energy efficient engine shroudless, hollow fan blade technology report

NASA Technical Reports Server (NTRS)

Michael, C. J.

1981-01-01

The Shroudless, Hollow Fan Blade Technology program was structured to support the design, fabrication, and subsequent evaluation of advanced hollow and shroudless blades for the Energy Efficient Engine fan component. Rockwell International was initially selected to produce hollow airfoil specimens employing the superplastic forming/diffusion bonding (SPF/DB) fabrication technique. Rockwell demonstrated that a titanium hollow structure could be fabricated utilizing SPF/DB manufacturing methods. However, some problems such as sharp internal cavity radii and unsatisfactory secondary bonding of the edge and root details prevented production of the required quantity of fatigue test specimens. Subsequently, TRW was selected to (1) produce hollow airfoil test specimens utilizing a laminate-core/hot isostatic press/diffusion bond approach, and (2) manufacture full-size hollow prototype fan blades utilizing the technology that evolved from the specimen fabrication effort. TRW established elements of blade design and defined laminate-core/hot isostatic press/diffusion bonding fabrication techniques to produce test specimens. This fabrication technology was utilized to produce full size hollow fan blades in which the HIP'ed parts were cambered/twisted/isothermally forged, finish machined, and delivered to Pratt & Whitney Aircraft and NASA for further evaluation.

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

Bayesian Estimation of Pneumonia Etiology: Epidemiologic Considerations and Applications to the Pneumonia Etiology Research for Child Health Study

PubMed Central

Fu, Wei; Shi, Qiyuan; Prosperi, Christine; Wu, Zhenke; Hammitt, Laura L.; Feikin, Daniel R.; Baggett, Henry C.; Howie, Stephen R.C.; Scott, J. Anthony G.; Murdoch, David R.; Madhi, Shabir A.; Thea, Donald M.; Brooks, W. Abdullah; Kotloff, Karen L.; Li, Mengying; Park, Daniel E.; Lin, Wenyi; Levine, Orin S.; O’Brien, Katherine L.; Zeger, Scott L.

2017-01-01

Abstract In pneumonia, specimens are rarely obtained directly from the infection site, the lung, so the pathogen causing infection is determined indirectly from multiple tests on peripheral clinical specimens, which may have imperfect and uncertain sensitivity and specificity, so inference about the cause is complex. Analytic approaches have included expert review of case-only results, case–control logistic regression, latent class analysis, and attributable fraction, but each has serious limitations and none naturally integrate multiple test results. The Pneumonia Etiology Research for Child Health (PERCH) study required an analytic solution appropriate for a case–control design that could incorporate evidence from multiple specimens from cases and controls and that accounted for measurement error. We describe a Bayesian integrated approach we developed that combined and extended elements of attributable fraction and latent class analyses to meet some of these challenges and illustrate the advantage it confers regarding the challenges identified for other methods. PMID:28575370

Scanning Miniature Microscopes without Lenses

NASA Technical Reports Server (NTRS)

Wang, Yu

2009-01-01

The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the nonpolarizing beam splitter were replaced by a polarizing one, then the specimen would be illuminated by s-polarized light. Upon reflection from the specimen, some of the s-polarized light would become p-polarized. Only the p-polarized light would contribute to the image on the CCD; in other words, the image would contain information on the polarization rotating characteristic of the specimen.

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...

Designing a Uniaxial Tension/Compression Test for Springback Analysis in High-Strength Steel Sheets

PubMed Central

Stoudt, M. R.; Levine, L. E.; Ma, L.

2016-01-01

We describe an innovative design for an in-plane measurement technique that subjects thin sheet metal specimens to bidirectional loading. The goal of this measurement is to provide the critical performance data necessary to validate complex predictions of the work hardening behavior during reversed uniaxial deformation. In this approach, all of the principal forces applied to the specimen are continually measured in real-time throughout the test. This includes the lateral forces that are required to prevent out of plane displacements in the specimen that promote buckling. This additional information will, in turn, improve the accuracy of the compensation for the friction generated between the anti-bucking guides and the specimen during compression. The results from an initial series of experiments not only demonstrate that our approach is feasible, but that it generates data with the accuracy necessary to quantify the directionally-dependent changes in the yield behavior that occur when the strain path is reversed (i.e., the Bauschinger Effect). PMID:28133391

Design and Performance Checks of the NPL Axial Heat Flow Apparatus

NASA Astrophysics Data System (ADS)

Wu, J.; Clark, J.; Stacey, C.; Salmon, D.

2015-03-01

This paper describes the design and performance checks of the NPL axial heat flow apparatus developed at the National Physical Laboratory for measurement of thermal conductivity. This apparatus is based on an absolute steady-state technique and is suitable for measuring specimens with thermal conductivities in the range from to and at temperatures between and . A uniform heat flow is induced in a cylindrical bar-shaped specimen that is firmly clamped between a guarded heater unit at the top and a water-cooled base. Heat is supplied at a known rate at the top end of the specimen by the heater unit and constrained to flow axially through the specimen by a surrounding edge-guard system, which is closely matched to the temperature gradient within the test specimen. The performance of this apparatus has been checked against existing NPL thermal-conductivity reference materials NPL 2S89 (based on Stainless Steel 310) and BSC Pure Iron (pure iron supplied by the British Steel Corporation with 99.96 % purity). The measured data produced by the newly designed NPL axial heat flow apparatus agree with the reference data for NPL 2S89 within 2 % and with that of BSC Pure Iron to within 3 % at temperatures from to . This apparatus is being used to provide accurate measurements to industrial and academic organizations and has also been used to develop a new range of NPL reference materials for checking other experimental techniques and procedures for thermal-conductivity measurements.

Design of Artificially Cracked Concrete Specimens for Virginia Department of Transportation Material Evaluation

DOT National Transportation Integrated Search

2018-05-01

The penetration of chloride ions and moisture through cracks in reinforced concrete structures can accelerate the corrosion of steel reinforcement and shorten the service life of the structure. The purpose of this study was to develop a method for si...

Advanced imaging techniques II: using a compound microscope for photographing point-mount specimens

USDA-ARS?s Scientific Manuscript database

Digital imaging technology has revolutionized the practice photographing insects for scientific study. Herein described are lighting and mounting techniques designed for imaging micro Hymenoptera. Techniques described here are applicable to all small insects, as well as other invertebrates. The ke...

Large strain cruciform biaxial testing for FLC detection

NASA Astrophysics Data System (ADS)

Güler, Baran; Efe, Mert

2017-10-01

Selection of proper test method, specimen design and analysis method are key issues for studying formability of sheet metals and detection of their forming limit curves (FLC). Materials with complex microstructures may need an additional micro-mechanical investigation and accurate modelling. Cruciform biaxial test stands as an alternative to standard tests as it achieves frictionless, in-plane, multi-axial stress states with a single sample geometry. In this study, we introduce a small-scale (less than 10 cm) cruciform sample allowing micro-mechanical investigation at stress states ranging from plane strain to equibiaxial. With successful specimen design and surface finish, large forming limit strains are obtained at the test region of the sample. The large forming limit strains obtained by experiments are compared to the values obtained from Marciniak-Kuczynski (M-K) local necking model and Cockroft-Latham damage model. This comparison shows that the experimental limiting strains are beyond the theoretical values, approaching to the fracture strain of the two test materials: Al-6061-T6 aluminum alloy and DC-04 high formability steel.

Experimental development of processes to produce homogenized alloys of immiscible metals, phase 3

NASA Technical Reports Server (NTRS)

Reger, J. L.

1976-01-01

An experimental drop tower package was designed and built for use in a drop tower. This effort consisted of a thermal analysis, container/heater fabrication, and assembly of an expulsion device for rapid quenching of heated specimens during low gravity conditions. Six gallium bismuth specimens with compositions in the immiscibility region (50 a/o of each element) were processed in the experimental package: four during low gravity conditions and two under a one gravity environment. One of the one gravity processed specimens did not have telemetry data and was subsequently deleted for analysis since the processing conditions were not known. Metallurgical, Hall effect, resistivity, and superconductivity examinations were performed on the five specimens. Examination of the specimens showed that the gallium was dispersed in the bismuth. The low gravity processed specimens showed a relatively uniform distribution of gallium, with particle sizes of 1 micrometer or less, in contrast to the one gravity control specimen. Comparison of the cooling rates of the dropped specimens versus microstructure indicated that low cooling rates are more desirable.

Apparatus for Hot Impact Testing of Material Specimens

NASA Technical Reports Server (NTRS)

Pawlik, Ralph J.; Choi, Sung R.

2006-01-01

An apparatus for positioning and holding material specimens is a major subsystem of a system for impact testing of the specimens at temperatures up to 1,500 C. This apparatus and the rest of the system are designed especially for hot impact testing of advanced ceramics, composites, and coating materials. The apparatus includes a retaining fixture on a rotating stage on a vertically movable cross support driven by a linear actuator. These components are located below a furnace wherein the hot impact tests are performed (see Figure 1). In preparation for a test, a specimen is mounted on the retaining fixture, then the cross support is moved upward to raise the specimen, through an opening in the bottom of the furnace, to the test position inside the furnace. On one side of the furnace there is another, relatively small opening on a direct line to the specimen. Once the specimen has become heated to the test temperature, the test is performed by using an instrumented external pressurized-gas-driven gun to shoot a projectile through the side opening at the specimen.

Structure-property relations and crack resistance at the bovine dentin-enamel junction.

PubMed

Lin, C P; Douglas, W H

1994-05-01

The present report is a study of the fracture behavior of the dentin-enamel complex, involving enamel, dentin, and the dentin-enamel junction (DEJ), that combines experimental design, computational finite element analysis, and fractography. Seven chevron-notched short-bar bovine DEJ specimens were utilized in this study. The general plane of the DEJ was approximately perpendicular to the fracture plane. All specimens were stored at 37 degrees C and 100% relative humidity for 24 h prior to being tested. A fracture test set-up was designed for application of tensile load on the DEJ specimens to initiate a crack at the vertex of the chevron in the enamel, across the DEJ zone and into the bulk dentin. During fracture testing, a water chamber was used to avoid dehydration of the specimen. The results showed that the lower boundary value of the fracture toughness of the DEJ perpendicular to its own plane was 3.38 +/- 0.40 MN/m1.5 and 988.42 +/- 231.39 J/m2, in terms of KIC and GKC, respectively. In addition, there was an extensive plastic deformation (83 +/- 12%) collateral to the fracture process at the DEJ zone. The fractography revealed that the deviation of the crak path involved an area which was approximately 50-100 microns deep. The parallel-oriented coarse collagen bundles with diameters of 1-5 microns at the DEJ zone may play a significant role in resisting the enamel crack. This reflects the fact, that in the intact tooth, the multiple full thickness cracks commonly found in enamel do not typically cause total failure of the tooth by crack extension into the dentin.

Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

NASA Technical Reports Server (NTRS)

Ratcliffe, James G.

2010-01-01

This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

Performance of lap splices in large-scale column specimens affected by ASR and/or DEF-extension phase.

DOT National Transportation Integrated Search

2015-03-01

A large experimental program, consisting of the design, construction, curing, exposure, and structural load : testing of 16 large-scale column specimens with a critical lap splice region that were influenced by varying : stages of alkali-silica react...

ADAPTATION OF CRACK GROWTH DETECTION TECHNIQUES TO US MATERIAL TEST REACTORS

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

A. Joseph Palmer; Sebastien P. Teysseyre; Kurt L. Davis

2015-04-01

A key component in evaluating the ability of Light Water Reactors to operate beyond 60 years is characterizing the degradation of materials exposed to radiation and various water chemistries. Of particular concern is the response of reactor materials to Irradiation Assisted Stress Corrosion Cracking (IASCC). Some test reactors outside the United States, such as the Halden Boiling Water Reactor (HBWR), have developed techniques to measure crack growth propagation during irradiation. The basic approach is to use a custom-designed compact loading mechanism to stress the specimen during irradiation, while the crack in the specimen is monitored in-situ using the Direct Currentmore » Potential Drop (DCPD) method. In 2012 the US Department of Energy commissioned the Idaho National Laboratory and the MIT Nuclear Reactor Laboratory (MIT NRL) to take the basic concepts developed at the HBWR and adapt them to a test rig capable of conducting in-pile IASCC tests in US Material Test Reactors. The first two and half years of the project consisted of designing and testing the loader mechanism, testing individual components of the in-pile rig and electronic support equipment, and autoclave testing of the rig design prior to insertion in the MIT Reactor. The load was applied to the specimen by means of a scissor like mechanism, actuated by a miniature metal bellows driven by pneumatic pressure and sized to fit within the small in-core irradiation volume. In addition to the loader design, technical challenges included developing robust connections to the specimen for the applied current and voltage measurements, appropriate ceramic insulating materials that can endure the LWR environment, dealing with the high electromagnetic noise environment of a reactor core at full power, and accommodating material property changes in the specimen, due primarily to fast neutron damage, which change the specimen resistance without additional crack growth. The project culminated with an in-pile demonstration at the MIT Reactor. The test rig and associated support equipment were used to apply loads to a representative Compact Tensile specimen during one MITR operating cycle, while measuring crack growth using the DCPD method. Although the test period was short (approximately 70 days), and the accumulated neutron dose relatively small, successful operation of the test rig was demonstrated. The specimen was cycled more than 8000 times (more than would be typical for a long term IASCC test), which was sufficient to propagate a crack of over 2 mm.« less

Fracture toughness testing on ferritic alloys using the electropotential technique

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

Huang, F.H.; Wire, G.L.

1981-06-11

Fracture toughness measurements as done conventionally require large specimens (5 x 5 x 2.5 cm) which would be prohibitively expensive to irradiate over the fluence and temperature ranges required for first wall design. To overcome this difficulty a single specimen technique for J intergral fracture toughness measurements on miniature specimens (1.6 cm OD x 0.25 cm thick) was developed. Comparisons with specimens three times as thick show that the derived J/sub 1c/ is constant, validating the specimen for first wall applications. The electropotential technique was used to obtain continuous crack extension measurements, allowing a ductile fracture resistence curve to bemore » constructed from a single specimen. The irradiation test volume required for fracture toughness measurements using both miniature specimens and single specimen J measurements was reduced a factor of 320, making it possible to perform a systematic exploration of irradiation temperature and dose variables as required for qualification of HT-9 and 9Cr-1Mo base metal and welds for first wall application. Fracture toughness test results for HT-9 and 9Cr-1Mo from 25 to 539/sup 0/C are presented to illustrate the single specimen technique.« less

Slow Crack Growth Behavior and Life/Reliability Analysis of 96 wt % Alumina at Ambient Temperature With Various Specimen/Loading Configurations

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Powers, Lynn M.; Nemeth, Noel N.

2000-01-01

Extensive constant stress-rate testing for 96 wt % alumina was conducted in room-temperature distilled water using four different specimen/loading configurations: rectangular beam test specimens under four-point uniaxial flexure, square plate test specimens in ring-on-ring biaxial flexure, square plate test specimens in ball-on-ring biaxial flexure, and dog-boned tensile test specimens in pure tension. The slow crack growth (SCG) parameter n was almost independent of specimen/loading configurations, in either four-point uniaxial flexure, ring-on-ring biaxial flexure, ball-on-ring biaxial flexure, or pure tension, ranging from n = 35 to 47 with an average value of n = 41.1 +/- 4.5. The prediction of fatigue strength/reliability based on the four-point uniaxial flexure data by using the CARES/Life design code as well as a simple PIA model was in good agreement with both the ring-on-ring biaxial and the ball-on-ring biaxial flexure data. A poor prediction using the PIA model was observed for the dog-boned tensile test specimens, presumably due to different flaw population involved in the tensile test specimens.

Analytical and experimental investigation of aircraft metal structures reinforced with filamentary composites. Phase 2: Structural fatigue, thermal cycling, creep, and residual strength

NASA Technical Reports Server (NTRS)

Blichfeldt, B.; Mccarty, J. E.

1972-01-01

Specimens representative of metal aircraft structural components reinforced with boron filamentary composites were manufactured and tested under cyclic loading, cyclic temperature, or continuously applied loading to evaluate some of the factors that affect structural integrity under cyclic conditions. Bonded, stepped joints were used throughout to provide composite-to-metal transition regions at load introduction points. Honeycomb panels with titanium or aluminum faces reinforced with unidirectional boron composite were fatigue tested at constant amplitude under completely reversed loading. Results indicated that the matrix material was the most fatigue-sensitive part of the design, with debonding initiating in the stepped joints. However, comparisons with equal weight all-metal specimens show a 10 to 50 times improved fatigue life. Fatigue crack propagation and residual strength were studied for several different stiffened panel concepts, and were found to vary considerably depending on the configuration. Composite-reinforced metal specimens were also subjected to creep and thermal cycling tests. Thermal cycling of stepped joint tensile specimens resulted in a ten percent decrease in residual strength after 4000 cycles.

Fabrication and testing of prestressed composite rotor blade spar specimens

NASA Technical Reports Server (NTRS)

Gleich, D.

1974-01-01

Prestressed composite spar specimens were fabricated and evaluated by crack propagation and ballistic penetration tests. The crack propagation tests on flawed specimens showed that the prestressed composite spar construction significantly suppresses crack growth. Damage from three high velocity 30 caliber projectile hits was confined to three small holes in the ballistic test specimen. No fragmentation or crack propagation was observed indicating good ballistic damage resistance. Rotor attachment approaches and improved structural performance configurations were identified. Design theory was verified by tests. The prestressed composite spar configuration consisted of a compressively prestressed high strength ARDEFORM 301 stainless steel liner overwrapped with pretensioned S-994 fiberglass.

Development of test specimens to obtain the transmission factors to attenuate photons of 0.511 MeV

NASA Astrophysics Data System (ADS)

Costa, J. J. S.; Cardoso, D. D.; Gavazza, S.; Oliveira, C. L.; Morales, R. K.; Amorim, A. S.; Balthar, M. C. V.; Oliveira, L. S. R.

2018-03-01

For designing a shielding, it is necessary, mainly, to determine or have access to the following parameters: transmission factors of the material used and type of radiation to be shielded. Cylindrical test specimens with different thicknesses were developed for experimentally obtaining the material transmission factor for shielding calculation. The cylindrical test specimens were made considering the geometric characteristics of the detector, the ease of production and the energy of 0.511 MeV from the 18F-FDG decay. A type of concrete widely used in Brazil was used in the preparation of the cylindrical test specimens.

Catalog of type specimens of recent mammals: Rodentia (Myomorpha, Anomaluromorpha, and Hystricomorpha) in the National Museum of Natural History, Smithsonian Institution

USGS Publications Warehouse

Fisher, Robert D.; Ludwig, Craig A.

2014-01-01

The type collection of Recent mammals in the Division of Mammals, National Museum of Natural History, Smithsonian Institution, contains 945 specimens bearing names of 931 species-group taxa of Rodentia (Myomorpha, Anomaluromorpha, and Hystricomorpha) as of August 2013. This catalog presents an annotated list of these holdings comprised of 905 holotypes, 16 lectotypes, 8 syntypes (48 specimens), and 2 neotypes. In addition, we include 44 specimens that are part of syntype series that should be in the collection but cannot be found or are now known to be in other collections. One hundred and ten of the names are new since the last type catalog covering these suborders A lectotype for Mus peruvianus Peale, 1848, is newly designated herein. Nine specimens previously reported were subsequently sent to the vertebrate paleontology collection and are not included here. Suborders and families are ordered as in Carleton and Musser; within families, currently recognized genera are arranged alphabetically; within each currently recognized genus, accounts are arranged alphabetically by original published name. Information in each account includes original name and abbreviated citation thereto, current name if other than original, citation for first use of current name combination for the taxon (or new name combination if used herein for the first time), type designation, U.S. National Museum catalog number(s), preparation, age and sex, date of collection and collector, original collector number, type locality, and remarks as appropriate. Digital photographs of each specimen will serve as a condition report and will be attached to each electronic specimen record.

Catalog of type specimens of recent mammals: Rodentia (Sciuromorpha and Castorimorpha) in the National Museum of Natural History, Smithsonian Institution

USGS Publications Warehouse

Fisher, Robert D.; Ludwig, Craig A.

2012-01-01

The type collection of Recent mammals in the Division of Mammals, National Museum of Natural History, Smithsonian Institution, contains 843 specimens bearing names of 820 species group taxa of Rodentia (Sciuromorpha and Castorimorpha) as of July 2011. This catalog presents a list of these holdings, which comprise 798 holotypes, 14 lectotypes, seven syntypes (30 specimens), and one neotype. In addition, we include three holotypes and 10 specimens that are part of syntype series that should be in the collection but cannot be found and three syntypes that were originally in this collection but are now known to be in other collections. One specimen that no longer has name-bearing status is included for the record. Forty-one of the names are new since the last type catalog. One new lectotype is designated. Suborders and families are listed as in Wilson and Reeder. Within families, currently recognized genera are arranged alphabetically. Within each currently recognized genus, accounts are arranged alphabetically by original published name. Information in each account includes original name and abbreviated citation thereto, current name if other than original, citation for first use of current name combination for the taxon (or new name combination if used herein for the first time), type designation, U.S. National Museum catalog number(s), preparation, age and sex, type locality, date of collection and name of collector, collector’s original number, and comments or additional information as appropriate. Digital photographs of each specimen serve as a condition report and will be linked to each electronic specimen record.

Effect of Premolar Axial Wall Height on Computer-Aided Design/Computer-Assisted Manufacture Crown Retention.

PubMed

Martin, Curt; Harris, Ashley; DuVall, Nicholas; Wajdowicz, Michael; Roberts, Howard Wayne

2018-03-28

To evaluate the effect of premolar axial wall height on the retention of adhesive, full-coverage, computer-aided design/computer-assisted manufacture (CAD/CAM) restorations. A total of 48 premolar teeth randomized into four groups (n = 12 per group) received all-ceramic CAD/CAM restorations with axial wall heights (AWH) of 3, 2, 1, and 0 mm and 16-degree total occlusal convergence (TOC). Specimens were restored with lithium disilicate material and cemented with self-adhesive resin cement. Specimens were loaded to failure after 24 hours. The 3- and 2-mm AWH specimens demonstrated significantly greater failure load. Failure analysis suggests a 2-mm minimum AWH for premolars with a TOC of 16 degrees. Adhesive technology may compensate for compromised AWH.

In Situ Microstructural Control and Mechanical Testing Inside the Transmission Electron Microscope at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Wang, Baoming; Haque, M. A.

2015-08-01

With atomic-scale imaging and analytical capabilities such as electron diffraction and energy-loss spectroscopy, the transmission electron microscope has allowed access to the internal microstructure of materials like no other microscopy. It has been mostly a passive or post-mortem analysis tool, but that trend is changing with in situ straining, heating and electrical biasing. In this study, we design and demonstrate a multi-functional microchip that integrates actuators, sensors, heaters and electrodes with freestanding electron transparent specimens. In addition to mechanical testing at elevated temperatures, the chip can actively control microstructures (grain growth and phase change) of the specimen material. Using nano-crystalline aluminum, nickel and zirconium as specimen materials, we demonstrate these novel capabilities inside the microscope. Our approach of active microstructural control and quantitative testing with real-time visualization can influence mechanistic modeling by providing direct and accurate evidence of the fundamental mechanisms behind materials behavior.

Examining Mechanical Strength Characteristics of Selective Inhibition Sintered HDPE Specimens Using RSM and Desirability Approach

NASA Astrophysics Data System (ADS)

Rajamani, D.; Esakki, Balasubramanian

2017-09-01

Selective inhibition sintering (SIS) is a powder based additive manufacturing (AM) technique to produce functional parts with an inexpensive system compared with other AM processes. Mechanical properties of SIS fabricated parts are of high dependence on various process parameters importantly layer thickness, heat energy, heater feedrate, and printer feedrate. In this paper, examining the influence of these process parameters on evaluating mechanical properties such as tensile and flexural strength using Response Surface Methodology (RSM) is carried out. The test specimens are fabricated using high density polyethylene (HDPE) and mathematical models are developed to correlate the control factors to the respective experimental design response. Further, optimal SIS process parameters are determined using desirability approach to enhance the mechanical properties of HDPE specimens. Optimization studies reveal that, combination of high heat energy, low layer thickness, medium heater feedrate and printer feedrate yielded superior mechanical strength characteristics.

Rapid, cost-effective, sensitive and quantitative detection of Acinetobacter baumannii from pneumonia patients

PubMed Central

Nomanpour, B; Ghodousi, A; Babaei, A; Abtahi, HR; Tabrizi, M; Feizabadi, MM

2011-01-01

Background and Objectives Pneumonia with Acinetobacter baumannii has a major therapeutic problem in health care settings. Decision to initiate correct antibiotic therapy requires rapid identification and quantification of organism. The aim of this study was to develop a rapid and sensitive method for direct detection of A. baumannii from respiratory specimens. Materials and Methods A Taqman real time PCR based on the sequence of bla oxa-51 was designed and used for direct detection of A. baumannii from 361 respiratory specimens of patients with pneumonia. All specimens were checked by conventional bacteriology in parallel. Results The new real time PCR could detect less than 200 cfu per ml of bacteria in specimens. There was agreement between the results of real time PCR and culture (Kappa value 1.0, p value<0.001). The sensitivity, specificity and predictive values of real time PCR were 100%. The prevalence of A. baumannii in pneumonia patients was 10.53 % (n=38). Poly-microbial infections were detected in 65.71% of specimens. Conclusion Acinetobacter baumannii is the third causative agent in nosocomial pneumonia after Pseudomonas aeroginosa (16%) and Staphylococcus aureus (13%) at Tehran hospitals. We recommend that 104 CFU be the threshold for definition of infection with A. baumannii using real time PCR. PMID:22530083

Evaluation of energy absorption of new concepts of aircraft composite subfloor intersections

NASA Technical Reports Server (NTRS)

Jones, Lisa E.; Carden, Huey D.

1989-01-01

Forty-one composite aircraft subfloor intersection specimens were tested to determine the effects of geometry and material on the energy absorbing behavior, failure characteristics, and post-crush structural integrity of the specimens. The intersections were constructed of twelve ply + or - 45 sub 6 laminates of either Kevlar 49/934 or AS-4/934 graphite-epoxy in heights of 4, 8, and 12 inches. The geometry of the specimens varied in the designs of the intersection attachment angle. Four different geometries were tested.

The Influence of Strain-Rate History and Temperature on the Shear Strength of Copper, Titanium and Mild Steel

DTIC Science & Technology

1976-03-01

Temperature dependence of flow stress of titanium, at (a) low and (b) high strain rates. 76 18 Strain dependence of apparent and intrinsic strain-rate...Cryostat in position surrounding specimen 98 B3 General view of low- temperature apparatus 98 CI Design of high - temperature titanium specimen and grip 99 C2... High - temperature titanium specimen and stainless- steel grips 100 C3 Transmission of torsional wave through mechanical connectors, at (a) 2000C (b

Principles and practices of irradiation creep experiment using pressurized mini-bellows

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

Byun, Thak Sang; Li, Meimei; Snead, Lance Lewis

2013-01-01

This article is to describe the key design principles and application practices of the newly developed in-reactor irradiation creep testing technology using pressurized mini-bellows. Miniature creep test frames were designed to fit into the high flux isotope reactor (HFIR) rabbit capsule whose internal diameter is slightly less than 10 mm. The most important consideration for this in-reactor creep testing technology was the ability of the small pressurized metallic bellows to survive irradiation at elevated temperatures while maintaining applied load to the specimen. Conceptual designs have been developed for inducing tension and compression stresses in specimens. Both the theoretical model andmore » the in-furnace test confirmed that a gas-pressurized bellows can produce high enough stress to induce irradiation creep in subsize specimens. Discussion focuses on the possible stress range in specimens induced by the miniature gas-pressurized bellows and the limitations imposed by the size and structure of thin-walled bellows. A brief introduction to the in-reactor creep experiment for graphite is provided to connect to the companion paper describing the application practices and irradiation creep data. An experimental and calculation procedure to obtain in-situ applied stress values from post irradiation in-furnace force measurements is also presented.« less

Design and construction of a guarded hot plate apparatus operating down to liquid nitrogen temperature.

PubMed

Li, Manfeng; Zhang, Hua; Ju, Yonglin

2012-07-01

A double-sided guarded hot plate apparatus (GHP) is specifically designed, fabricated, and constructed for the measurement of thermal conductivities of insulation specimens operated down to liquid nitrogen temperature (-196 °C), at different controlled pressures from 0.005 Pa to 0.105 MPa. The specimens placed in this apparatus are 300 mm in diameter at various thicknesses ranging from 4 mm to 40 mm. The apparatus is different from traditional GHP in terms of structure, supporting and heating method. The details of the design and construction of the hot plate, the cold plates, the suspensions, the clampings, and the vacuum chamber of the system are presented. The measurement methods of the temperatures, the input power, the meter area, and the thickness of the specimens are given. The apparatus is calibrated with teflon plates as sample and the maximum deviation from the published data is about 6% for thermal conductivity. The uncertainties for the measurement are also discussed in this paper.

Does Pneumatic Tube System Transport Contribute to Hemolysis in ED Blood Samples?

PubMed Central

Phelan, Michael P.; Reineks, Edmunds Z.; Hustey, Fredric M.; Berriochoa, Jacob P.; Podolsky, Seth R.; Meldon, Stephen; Schold, Jesse D.; Chamberlin, Janelle; Procop, Gary W.

2016-01-01

Introduction Our goal was to determine if the hemolysis among blood samples obtained in an emergency department and then sent to the laboratory in a pneumatic tube system was different from those in samples that were hand-carried. Methods The hemolysis index is measured on all samples submitted for potassium analysis. We queried our hospital laboratory database system (SunQuest®) for potassium results for specimens obtained between January 2014 and July 2014. From facility maintenance records, we identified periods of system downtime, during which specimens were hand-carried to the laboratory. Results During the study period, 15,851 blood specimens were transported via our pneumatic tube system and 92 samples were hand delivered. The proportions of hemolyzed specimens in the two groups were not significantly different (13.6% vs. 13.1% [p=0.90]). Results were consistent when the criterion was limited to gross (3.3% vs 3.3% [p=0.99]) or mild (10.3% vs 9.8% [p=0.88]) hemolysis. The hemolysis rate showed minimal variation during the study period (12.6%–14.6%). Conclusion We found no statistical difference in the percentages of hemolyzed specimens transported by a pneumatic tube system or hand delivered to the laboratory. Certain features of pneumatic tube systems might contribute to hemolysis (e.g., speed, distance, packing material). Since each system is unique in design, we encourage medical facilities to consider whether their method of transport might contribute to hemolysis in samples obtained in the emergency department. PMID:27625719

Does Pneumatic Tube System Transport Contribute to Hemolysis in ED Blood Samples?

PubMed

Phelan, Michael P; Reineks, Edmunds Z; Hustey, Fredric M; Berriochoa, Jacob P; Podolsky, Seth R; Meldon, Stephen; Schold, Jesse D; Chamberlin, Janelle; Procop, Gary W

2016-09-01

Our goal was to determine if the hemolysis among blood samples obtained in an emergency department and then sent to the laboratory in a pneumatic tube system was different from those in samples that were hand-carried. The hemolysis index is measured on all samples submitted for potassium analysis. We queried our hospital laboratory database system (SunQuest(®)) for potassium results for specimens obtained between January 2014 and July 2014. From facility maintenance records, we identified periods of system downtime, during which specimens were hand-carried to the laboratory. During the study period, 15,851 blood specimens were transported via our pneumatic tube system and 92 samples were hand delivered. The proportions of hemolyzed specimens in the two groups were not significantly different (13.6% vs. 13.1% [p=0.90]). Results were consistent when the criterion was limited to gross (3.3% vs 3.3% [p=0.99]) or mild (10.3% vs 9.8% [p=0.88]) hemolysis. The hemolysis rate showed minimal variation during the study period (12.6%-14.6%). We found no statistical difference in the percentages of hemolyzed specimens transported by a pneumatic tube system or hand delivered to the laboratory. Certain features of pneumatic tube systems might contribute to hemolysis (e.g., speed, distance, packing material). Since each system is unique in design, we encourage medical facilities to consider whether their method of transport might contribute to hemolysis in samples obtained in the emergency department.

The MANTA: An RPV design to investigate forces and moments on a lifting surface

NASA Technical Reports Server (NTRS)

Bryan, Kevin; Soutar, John; Witty, Peter; Mediate, Bruno; Quast, Thomas; Combs, Dan; Schubert, Martin; Condron, David; Taylor, Scott; Garino, ED

1989-01-01

The overall goal was to investigate and exploit the advantages of using remotely powered vehicles (RPV's) for in-flight data collection at low Reynold's numbers. The data to be collected is on actual flight loads for any type of rectangular or tapered airfoil section, including vertical and horizontal stabilizers. The data will be on a test specimen using a force-balance system which is located forward of the aircraft to insure an undisturbed air flow over the test section. The collected data of the lift, drag and moment of the test specimen is to be radioed to a grand receiver, thus providing real-time data acquisition. The design of the mission profile and the selection of the instrumentation to satisfy aerodynamic requirements are studied and tested. A half-size demonstrator was constructed and flown to test the flight worthiness of the system.

Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

PubMed Central

Wu, J.S.; Kim, A. M.; Bleher, R.; Myers, B.D.; Marvin, R. G.; Inada, H.; Nakamura, K.; Zhang, X.F.; Roth, E.; Li, S.Y.; Woodruff, T. K.; O'Halloran, T. V.; Dravid, Vinayak P.

2013-01-01

A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room- and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. PMID:23500508

A hybrid scanning force and light microscope for surface imaging and three-dimensional optical sectioning in differential interference contrast.

PubMed

Stemmer, A

1995-04-01

The design of a scanned-cantilever-type force microscope is presented which is fully integrated into an inverted high-resolution video-enhanced light microscope. This set-up allows us to acquire thin optical sections in differential interference contrast (DIC) or polarization while the force microscope is in place. Such a hybrid microscope provides a unique platform to study how cell surface properties determine, or are affected by, the three-dimensional dynamic organization inside the living cell. The hybrid microscope presented in this paper has proven reliable and versatile for biological applications. It is the only instrument that can image a specimen by force microscopy and high-power DIC without having either to translate the specimen or to remove the force microscope. Adaptation of the design features could greatly enhance the suitability of other force microscopes for biological work.

Design features and results from fatigue reliability research machines.

NASA Technical Reports Server (NTRS)

Lalli, V. R.; Kececioglu, D.; Mcconnell, J. B.

1971-01-01

The design, fabrication, development, operation, calibration and results from reversed bending combined with steady torque fatigue research machines are presented. Fifteen-centimeter long, notched, SAE 4340 steel specimens are subjected to various combinations of these stresses and cycled to failure. Failure occurs when the crack in the notch passes through the specimen automatically shutting down the test machine. These cycles-to-failure data are statistically analyzed to develop a probabilistic S-N diagram. These diagrams have many uses; a rotating component design example given in the literature shows that minimum size and weight for a specified number of cycles and reliability can be calculated using these diagrams.

Application of high-speed photography to the study of high-strain-rate materials testing

NASA Astrophysics Data System (ADS)

Ruiz, D.; Harding, John; Noble, J. P.; Hillsdon, Graham K.

1991-04-01

There is a growing interest in material behaviour at strain rates greater than 104sec1, for instance in the design of aero-engine turbine blades. It is necessary therefore, to develop material testing techniques that give well-defined information on mechanical behaviour in this very high strain-rate regime. A number of techniques are available, including the expanding ring test1, a miniaturised compression Hopkinson bar technique using direct impact and the double-notch shear test3 which has been described by Nicholas4 as "one of the most promising for future studies in dynamic plasticity". However, although it is believed to be a good test for determining the flow stress at shear strain rates of 104sec and above, the design of specimen used makes an accurate determination of strain extremely difficult while, in the later stages of the test the deformation mode involves rotation as well as shear. If this technique is to be used, therefore, it is necessary to examine in detail the progressive deformation and state of stress within the specimen during the impact process. An attempt can then be made to assess how far the data obtained is a reliable measure of the specimen material response and the test can be calibrated. An extensive three stage analysis has been undertaken. In the first stage, reported in a previous paper5, the initial elastic behaviour was studied. Dynamic photoelastic experiments were used to support linear elastic numerical results derived by the finite element method. Good qualitative agreement was obtained between the photoelastic experiment and the numerical model and the principal source of error in the elastic region of the double-notch shear test was identified as the assumption that all deformation of the specimen is concentrated in the two shear zones. For the epoxy (photoelastic) specimen a calibration factor of 5.3 was determined. This factor represents the ratio between the defined (nominal) gauge length and the effective gauge length. The second stage of the analysis of the double-notch shear (DNS) specimen is described in this paper. This consists of the use of ultra-high speed photography to provide information on the plastic deformation behaviour of the specimen. Two different high speed cine cameras were used for this work, a Hadland "Imacon" 792 electronic image converter camera and a Cordin 377 rotating mirror-drum optical camera. Implementation of the two cameras and photographic results are briefly compared and contrasted here. Stage three of this work consists of an advanced numerical analysis of the elasto-plastic, strain rate dependent behaviour of the DNS specimen. The principle intention of the authors was to use the physical data collected from high speed photographs for correlation with this work. Full details of the numerical work are presented elsewhere6 but some salient results will be given here for completeness.

Overview of experimental support for fission-product transport analyses at Oak Ridge National Laboratory

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

Wichner, R.P.

The program was designed to determine fission product and aerosol release rates from irradiated fuel under accident conditions, to identify the chemical forms of the released material, and to correlate the results with experimental and specimen conditions with the data from related experiments. These tests of PWR fuel were conducted and fuel specimen and test operating data are presented. The nature and rate of fission product vapor interaction with aerosols were studied. Aerosol deposition rates and transport in the reactor vessel during LWR core-melt accidents were studied. The Nuclear Safety Pilot Plant is dedicated to developing an expanded data basemore » on the behavior of aerosols generated during a severe accident.« less

Experimental study on the connection property of full-scale composite member

NASA Astrophysics Data System (ADS)

Panpan, Cao; Qing, Sun

2018-01-01

The excellent properties of composite result in its increasingly application in electric power construction, however there are less experimental studies on full-scale composite member connection property. Full-scale experiments of the connection property between E-glass fiber/epoxy reinforced polymer member and steel casing in practical engineering have been conducted. Based on the axial compression test of the designed specimens, the failure process and failure characteristics were observed, the load-displacement curves and strain distribution of the specimens were obtained. The finite element analysis was used to get the tensile connection strength of the component. The connection property of the components was analyzed to provide basis of the casing connection of GFRP application in practical engineering.

Structure and mechanical properties of Cresco-Ti laser-welded joints and stress analyses using finite element models of fixed distal extension and fixed partial prosthetic designs.

PubMed

Uysal, Hakan; Kurtoglu, Cem; Gurbuz, Riza; Tutuncu, Naki

2005-03-01

The Cresco-Ti System uses a laser-welded process that provides an efficient technique to achieve passive fit frameworks. However, mechanical behavior of the laser-welded joint under biomechanical stress factors has not been demonstrated. This study describes the effect of Cresco-Ti laser-welding conditions on the material properties of the welded specimen and analyzes stresses on the weld joint through 3-dimensional finite element models (3-D FEM) of implant-supported fixed dentures with cantilever extensions and fixed partial denture designs. Twenty Grade III (ASTM B348) commercially pure titanium specimens were machine-milled to the dimensions described in the EN10002-1 tensile test standard and divided into test (n = 10) and control (n = 10) groups. The test specimens were sectioned and laser-welded. All specimens were subjected to tensile testing to determine yield strength (YS), ultimate tensile strength (UTS), and percent elongation (PE). The Knoop micro-indentation test was performed to determine the hardness of all specimens. On welded specimens, the hardness test was performed at the welded surface. Data were analyzed with the Mann-Whitney U test and Student's t test (alpha=.05). Fracture surfaces were examined by scanning electron microscopy to characterize the mode of fracture and identify defects due to welding. Three-dimensional FEMs were created that simulated a fixed denture with cantilever extensions supported by 5 implants (M1) and a fixed partial denture supported by 2 implants (M2), 1 of which was angled 30 degrees mesio-axially. An oblique load of 400 N with 15 degrees lingual-axial inclinations was applied to both models at various locations. Test specimens fractured between the weld and the parent material. No porosities were observed on the fractured surfaces. Mean values for YS, UTS, PE, and Knoop hardness were 428 +/- 88 MPa, 574 +/- 113 MPa, 11.2 +/- 0.4%, 270 +/- 17 KHN, respectively, for the control group and 642 +/- 2 MPa, 772 +/- 72 MPa, 4.8 +/- 0.7%, 353 +/- 23 KHN, respectively, for the test group. The differences between the groups were significant for all mechanical properties ( P <.05). For both models, the FEA revealed that maximum principal stresses were concentrated at the framework-weld junction but did not exceed the UTS of the weld joint. Within the constraints of the finite element models, mechanical failure of the welded joint between the support and the framework may not be expected under biomechanical conditions simulated in this study.

The effect of thermocycling on the fracture toughness and hardness of core buildup materials.

PubMed

Medina Tirado, J I; Nagy, W W; Dhuru, V B; Ziebert, A J

2001-11-01

Thermocycling has been shown to cause surface degradation of many dental materials, but its effect on the fracture toughness and hardness of direct core buildup materials is unknown. This study was designed to determine the effect of thermocycling on the fracture toughness and hardness of 5 core buildup materials. Fifteen specimens were prepared from each of the following materials: Fluorocore, VariGlass VLC, Valiant PhD, Vitremer, and Chelon-Silver. American Standard for Testing Materials guidelines for single-edge notch, bar-shaped specimens were used. Ten specimens of each material were thermocycled for 2000 cycles; the other 5 specimens were not thermocycled. All specimens were subjected to 3-point bending in a universal testing machine. The load at fracture was recorded, and the fracture toughness (K(IC)) was calculated. Barcol hardness values were also determined. Data were analyzed with 1-way analysis of variance and compared with the Tukey multiple range test (P<.05). Pearson's correlation coefficient was also calculated to measure the association between fracture toughness and hardness. Fluorocore had the highest thermocycled mean K(IC) and Valiant PhD the highest non-thermocycled K(IC). Chelon-Silver demonstrated the lowest mean K(IC) both before and after thermocycling. One-way analysis of variance demonstrated significant differences between conditions, and the Tukey test showed significant differences (P<.05) between materials for both conditions. Most specimens also showed significant hardness differences between conditions. Pearson's correlation coefficient indicated only a mild-to-moderate correlation between hardness and fracture toughness. Within the limitations of this study, the thermocycling process negatively affected the fracture toughness and hardness of the core buildup materials tested.

A Comparative Study of the Retentive Strengths of Commercial and Indigenously Developed Luting Cements using Both Lathe-cut and Clinically Simulated Specimens.

PubMed

Mathew, Joe; Kurian, Byju P; Philip, Biju; Mohammed, Sunil; Menon, Preetha; Raj, Rajan S

2016-08-01

Superior adhesive strength in luting agents is of paramount significance in fixed partial denture success. In this in vitro study five cements were tested for retentive qualities, using both lathe-cut and hand-prepared specimens. A total of 104 freshly extracted tooth specimens were prepared. Seventy of them were lathe-cut and 30 specimens were hand-prepared to simulate clinical conditions. Five different cements were tested, which included a compomer, a composite, a zinc phosphate, and 2 glass-ionomer luting cements. Of the 5, 2 trial cements were indigenously developed by Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Trivandrum, India - a glass-ionomer cement (Chitra GIC) and a chemical-cure composite (Chitra CCC). All cements were compared within each group and between groups (lathe-prepared and hand-prepared). GC Fuji 1 (GC America) exhibited superior retentive strengths in both lathe-cut and hand-prepared specimens, whereas the compomer cement displayed the lowest values when tested. In lathe-cut specimens, statistical analysis showed no significant difference between GC Fuji 1 and indigenously developed Chitra CCC. Both Chitra CCC and GC Fuji 1 have comparable strengths in lathe-cut samples, making Chitra CCC a potential luting agent. Statistical analysis reveals that all cements, except GC Fuji 1, exhibited a significant decrease in strength due to the change in design uniformity. The chemical bonding of GC Fuji 1 proves to be quite strong irrespective of shape and precision of the tooth crown. The indigenously developed Chitra GIC and Chitra CCC showed promising results to be used as a potential luting agent.

Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia.

PubMed

Dewaele, Leonard; Tsogtbaatar, Khishigjav; Barsbold, Rinchen; Garcia, Géraldine; Stein, Koen; Escuillié, François; Godefroit, Pascal

2015-01-01

The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abundant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown to adult individuals. Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The skull length of these babies is around 5% that of the largest known S. angustirostris specimens, so these specimens document the earliest development stages of this giant hadrosaur and bridge a large hiatus in our knowledge of the ontogeny of S. angustirostris. The studied specimens are likely part of a nest originally located on a riverbank point bar. The perinatal specimens were buried by sediment carried by the river current presumably during the wet summer season. Perinatal bones already displayed diagnostic characters for Saurolophus angustirostris, including premaxillae with a strongly reflected oral margin and upturned premaxillary body in lateral aspect. The absence of a supracranial crest and unfused halves of the cervical neural arches characterize the earliest stages in the ontogeny of S. angustirostris. The eggshell fragments associated with the perinatal individuals can be referred to the Spheroolithus oogenus and closely resemble those found in older formations (e.g. Barun Goyot Fm in Mongolia) or associated with more basal hadrosauroids (Bactrosaurus-Gilmoreosaurus in the Iren Dabasu Fm, Inner Mongolia, China). This observation suggests that the egg microstructure was similar in basal hadrosauroids and more advanced saurolophines. One of the authors (FE) is employed by the commercial organization Eldonia. Eldonia provided support in the form of a salary for FE, but did not have any additional role or influence in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and it does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials.

Experimental Verification of the Structural Glass Beam-Columns Strength

NASA Astrophysics Data System (ADS)

Pešek, Ondřej; Melcher, Jindřich; Balázs, Ivan

2017-10-01

This paper deals with experimental research of axially and laterally loaded members made of structural (laminated) glass. The purpose of the research is the evaluation of buckling strength and actual behaviour of the beam-columns due to absence of standards for design of glass load-bearing structures. The experimental research follows the previous one focusing on measuring of initial geometrical imperfections of glass members, testing of glass beams and columns. Within the frame of the research 9 specimens were tested. All of them were of the same geometry (length 2000 mm, width 200 mm and thickness 16 mm) but different composition - laminated double glass made of annealed glass or fully tempered glass panes bonded together by PVB or EVASAFE foil. Specimens were at first loaded by axial force and then by constantly increasing bending moment up to failure. During testing lateral deflections, vertical deflection and normal stresses at mid-span were measured. A maximum load achieved during testing has been adopted as flexural-lateral-torsional buckling strength. The results of experiments were statistically evaluated according to the European standard for design of structures EN 1990, appendix D. There are significant differences between specimens made of annealed glass or fully tempered glass. Differences between specimens loaded by axial forces 1 kN and 2 kN are negligible. The next step was to determine the design strength by calculation procedure based on buckling curves approach intended for design of steel columns and develop interaction criterion for glass beams-columns.

A combined RT-PCR and dot-blot hybridization method reveals the coexistence of SJNNV and RGNNV betanodavirus genotypes in wild meagre (Argyrosomus regius).

PubMed

Lopez-Jimena, B; Cherif, N; Garcia-Rosado, E; Infante, C; Cano, I; Castro, D; Hammami, S; Borrego, J J; Alonso, M C

2010-10-01

To detect the possible coexistence of striped jack nervous necrosis virus (SJNNV) and red-spotted grouper nervous necrosis virus (RGNNV) genotypes in a single fish, a methodology based on the combination of PCR amplification and blot hybridization has been developed and applied in this study. The degenerate primers designed for the PCR procedure target the T4 region within the capsid gene, resulting in the amplification of both genotypes. The subsequent hybridization of these amplification products with two different specific digoxigenin-labelled probes resulted in the identification of both genotypes separately. The application of the RT-PCR protocol to analyse blood samples from asymptomatic wild meagre (Argyrosomus regius) specimens has shown a 46.87% of viral nervous necrosis virus carriers. The combination of RT-PCR and blot hybridization increases the detection rate up to 90.62%, and, in addition, it has shown the coexistence of both genotypes in 18 out of the 32 specimens analysed (56.25%). This study reports the coexistence of betanodaviruses belonging to two different genotypes (SJNNV and RGNNV) in wild fish specimens. This is the first report demonstrating the presence of SJNNV and RGNNV genotypes in the same specimen. This study also demonstrates a carrier state in this fish species for the first time. © 2010 The Authors. Journal compilation © 2010 The Society for Applied Microbiology.

The Effects of Fresh Detox Juices on Color Stability and Roughness of Resin-Based Composites.

PubMed

Yikilgan, İhsan; Akgul, Sinem; Hazar, Ahmet; Kedıcı Alp, Cemile; Baglar, Serdar; Bala, Oya

2018-02-27

To evaluate the effects of three fresh detox juices, including an orange, green, and red beverage, on the color stability and surface roughness of three anterior esthetic resin-based composites (RBCs). Disk-shaped specimens were prepared with three different esthetic RBCs (Amaris, G-aenial Anterior, Clearfil Majesty ES-2) according to the manufacturers' instructions. Forty specimens were prepared for each RBC, and all specimens were stored in artificial saliva at 37°C for 24 hours. The initial color values and surface roughness measurements of the specimens were taken using a spectrophotometer and a profilometer. The specimens were then divided into 4 subgroups (n = 10). All specimens except the control specimens were immersed in their designated fresh detox juices (green, red, or orange) for 10 minutes twice a day. Color and surface roughness measurements were taken on day 15 and day 30, and the results were analyzed by one-way ANOVA and Tukey HSD test. The association between color change and surface roughness was evaluated by Spearman's Rank Correlation analysis. Color changes and surface roughness increased upon exposure to fresh detox juices for 15 and 30 days for all of the RBCs. All of the G-aenial and Amaris groups displayed color changes above the threshold of acceptability, whereas Clearfil Majesty ES-2 displayed a color change above the threshold of acceptability only after exposure to the red beverage for 30 days (ΔE > 3.7). With regard to surface roughness, Clearfil Majesty ES-2 outperformed the other RBCs (p < 0.001). According to Spearman's Rank Correlation analysis, there was no correlation between color change and surface roughness (p > 0.001). Exposure to the fresh detox juices used in this study led to similar color changes in the RBCs used in this study. © 2018 by the American College of Prosthodontists.

Time-of-flight atom-probe field-ion microscope for the study of defects in metals. Report No. 2357. [W--25 at. % Re

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

Hall, T.M.; Wagner, A.; Berger, A.S.

1975-06-01

An ultra-high vacuum time-of-flight (TOF) atom-probe field ion microscope (FIM) specifically designed for the study of defects in metals is described. The variable magnification FIM image is viewed with the aid of an internal image intensification system based on a channel electron-multiplier array. The specimen is held in a liquid-helium-cooled goniometer stage, and the specimen is exchanged by means of a high-vacuum (less than 10/sup -6/ torr) specimen exchange device. This stage allows the specimen to be maintained at a tip temperature anywhere in the range from 13 to 450/sup 0/K. Specimens can also be irradiated in-situ with any low-energymore » (less than 1 keV) gas ion employing a specially constructed ion gun. The pulse-field evaporated ions are detected by a Chevron ion-detector located 2.22 m from the FIM specimen. The TOF of the ions are measured by a specially constructed eight-channel digital timer with a resolution of +-10 ns. The entire process of applying the evaporation pulse to the specimen, measuring the dc and pulse voltages, and analyzing the TOF data is controlled by a NOVA 1220 computer. The computer is also interfaced to a Tektronix graphics terminal which displays the data in the form of a histogram of the number of events versus the mass-to-charge ratio. An extensive set of computer programs to test and operate the atom-probe FIM have been developed. With this automated system we can presently record and analyze 10 TOF s/sup -1/. In the performance tests reported here the instrument has resolved the seven stable isotopes of molybdenum, the five stable isotopes of tungsten, and the two stable isotopes of rhenium in a tungsten--25 at. percent rhenium alloy. (auth)« less

Growth and characterization of dexterous nonlinear optical material: Dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol (DMAPNP)

NASA Astrophysics Data System (ADS)

Saravanan, M.

2016-08-01

The crystals (dimethyl amino pyridinium 4-nitrophenolate 4-nitrophenol [DMAPNP] suitable for NLO applications were grown by the slow cooling method. The solubility and metastable zone width measurement of DMAPNP specimen was studied. The material crystallizes in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The ocular precision in the intact visible region was found to be good for non-linear optical claim. Quality of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of DMAPNP sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The third order nonlinear optical properties of DMAPNP crystals were premeditated by Z-scan method. Birefringence and optical homogeneity of the crystal were evaluated using modified channel spectrum method. The half wave voltage of the grown crystal deliberate from the elector optic experimentation. Photoconductivity measurement specified consummate of inducing dipoles owing to brawny incident radiation and also disclose the nonlinear activities of the grown specimen.

Parametric study and characterization of the isobaric thermomechanical transformation fatigue of nickel-rich NiTi SMA actuators

NASA Astrophysics Data System (ADS)

Bertacchini, Olivier W.; Schick, Justin; Lagoudas, Dimitris C.

2009-03-01

The recent development of various aerospace applications utilizing Ni-rich NiTi Shape memory Alloys (SMAs) as actuators motivated the need to characterize the cyclic response and the transformation fatigue behavior of such alloys. The fatigue life validation and certification of new designs is required in order to be implemented and used in future applications. For that purpose, a custom built fatigue test frame was designed to perform isobaric thermally induced transformation cycles on small dogbones SMA actuators (test gauge cross-section up to: 1.270 x 0.508 mm2). A parametric study on the cyclic response and transformation fatigue behavior of Ni-rich NiTi SMAs led to the optimization of several material/process and test parameters, namely: the applied stress range, the heat treatment, the heat treatment environment and the specimen thickness. However, fatigue testing was performed in a chilled waterless glycol environment maintained at a temperature of 5°C that showed evidence of corrosion-assisted transformation fatigue failure. Therefore, it was necessary to build a fatigue test frame that would employ a dry and inert cooling methodology to get away from any detrimental interactions between the specimens and the cooling medium (corrosion). The selected cooling method was gaseous nitrogen, sprayed into a thermally insulated chamber, maintaining a temperature of -20°C. The design of the gaseous nitrogen cooling was done in such a way that the actuation frequency is similar to the one obtained using the original design (~ 0.1 Hz). For both cooling methods, Joule resistive heating was used to heat the specimens. In addition and motivated by the difference in surface quality resulting from different material processing such as EDM wire cutting and heat treatments, EDM recast layer and oxide layer were removed. The removal was followed by an ultra-fine polish (0.05 μm) that was performed on a subset of the fatigue specimens. Experimental results are presented for full actuation of the SMA actuators and are given in terms of applied stress, accumulated plastic strain and number of cycles to failure. In addition, the assessment of the influence of the surface quality is supported by fatigue tests results and post-failure microstructure analysis.

Design of a rib impactor equipment

NASA Astrophysics Data System (ADS)

Torres, C. R.; García, G.; Aguilar, L. A.; Martínez, L.

2017-01-01

The human ribs must be analyzed as long and as curved bones, due to their physiology. For the development of an experimental equipment that simulate the application of loads, over the rib in the moment of a frontal collision in an automobile with seat belt, it was applied a methodology that constituted in the identification of needs and the variables which led the design of 3D model, from this it was used the technique of fused deposition modeling for the development of the equipment pieces. The supports that hold the rib ends were design with two and three degrees of freedom that allows the simulation of rib movement with the spine and the breastbone in the breathing. For the simulation of the seat belt, it was determined to applied two loads over the front part of the rib from the sagittal and lateral plane respectively, for this it was made a displacement through a lineal actuator with a speed of 4mm/s. The outcomes shown a design of an equipment able to obtain the load parameters required to generate fractures in rib specimens. The equipment may be used for the study of specimens with nearby geometries to the rib taken as a reference.

Front-Loading Sputum Microscopy Services: An Opportunity to Optimise Smear-Based Case Detection of Tuberculosis in High Prevalence Countries

PubMed Central

Ramsay, Andy; Yassin, Mohammed Ahmed; Cambanis, Alexis; Hirao, Susumu; Almotawa, Ahmad; Gammo, Mohamed; Lawson, Lovett; Arbide, Izabel; Al-Aghbari, Nasher; Al-Sonboli, Najla; Sherchand, Jeevan Bahadur; Gauchan, Punita; Cuevas, Luis Eduardo

2009-01-01

Setting. Ethiopia, Nepal, Nigeria, and Yemen. Objective. To reduce the time to complete sputum microscopy. Design. Cross-sectional surveys enrolling 923 patients with chronic cough in the 4 countries and using similar protocols. Spot-morning-spot sputum specimens were collected. An additional sputum specimen (Xspot) was collected one hour after the first, and the yields of the first two or the three specimens collected as spot-morning-spot or spot-Xspot-morning were compared. Results. 216 patients had ≥ one positive smear. 210 (97%) were identified by the spot-morning-spot, and 210 (97%) were identified by the spot-Xspot-morning specimens, with 203 and 200 identified by the first 2 specimens of each approach, respectively. Neither difference was significant. Conclusions. The time to complete smear microscopy could be reduced. PMID:20309419

Marginal discrepancy of noble metal-ceramic fixed dental prosthesis frameworks fabricated by conventional and digital technologies.

PubMed

Afify, Ahmed; Haney, Stephan; Verrett, Ronald; Mansueto, Michael; Cray, James; Johnson, Russell

2018-02-01

Studies evaluating the marginal adaptation of available computer-aided design and computer-aided manufacturing (CAD-CAM) noble alloys for metal-ceramic prostheses are lacking. The purpose of this in vitro study was to evaluate the vertical marginal adaptation of cast, milled, and direct metal laser sintered (DMLS) noble metal-ceramic 3-unit fixed partial denture (FDP) frameworks before and after fit adjustments. Two typodont teeth were prepared for metal-ceramic FDP abutments. An acrylic resin pattern of the prepared teeth was fabricated and cast in nickel-chromium (Ni-Cr) alloy. Each specimen group (cast, milled, DMLS) was composed of 12 casts made from 12 impressions (n=12). A single design for the FDP substructure was created on a laboratory scanner and used for designing the specimens in the 3 groups. Each specimen was fitted to its corresponding cast by using up to 5 adjustment cycles, and marginal discrepancies were measured on the master Ni-Cr model before and after laboratory fit adjustments. The milled and DMLS groups had smaller marginal discrepancy measurements than those of the cast group (P<.001). Significant differences were found in the number of adjustments among the groups, with the milled group requiring the minimum number of adjustments, followed by the DMLS and cast groups (F=30.643, P<.001). Metal-ceramic noble alloy frameworks fabricated by using a CAD-CAM workflow had significantly smaller marginal discrepancies compared with those with a traditional cast workflow, with the milled group demonstrating the best marginal fit among the 3 test groups. Manual refining significantly enhanced the marginal fit of all groups. All 3 groups demonstrated marginal discrepancies within the range of clinical acceptability. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Incorporating Informal Learning Environments and Local Fossil Specimens in Earth Science Classrooms: A Recipe for Success

ERIC Educational Resources Information Center

Clary, Renee M.; Wandersee, James H.

2009-01-01

In an online graduate paleontology course taken by practicing Earth Science teachers, we designed an investigation using teachers' local informal educational environments. Teachers (N = 28) were responsible for photographing, describing, and integrating fossil specimens from two informal sites into a paleoenvironmental analysis of the landscape in…

16 CFR § 1616.5 - Test procedure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... specimen holder to be used in this test method is detailed in Engineering Drawing Number 7. It is designed... hooks and weights shall be used to produce a series of loads for char length determinations. Suitable.... Shorter conditioning times may be used if the change in weight of a specimen in successive weighings made...

16 CFR 1616.5 - Test procedure.

Code of Federal Regulations, 2011 CFR

2011-01-01

... specimen holder to be used in this test method is detailed in Engineering Drawing Number 7. It is designed... hooks and weights shall be used to produce a series of loads for char length determinations. Suitable.... Shorter conditioning times may be used if the change in weight of a specimen in successive weighings made...

16 CFR 1616.5 - Test procedure.

Code of Federal Regulations, 2012 CFR

2012-01-01

... specimen holder to be used in this test method is detailed in Engineering Drawing Number 7. It is designed... hooks and weights shall be used to produce a series of loads for char length determinations. Suitable.... Shorter conditioning times may be used if the change in weight of a specimen in successive weighings made...

16 CFR 1616.5 - Test procedure.

Code of Federal Regulations, 2010 CFR

2010-01-01

... specimen holder to be used in this test method is detailed in Engineering Drawing Number 7. It is designed... hooks and weights shall be used to produce a series of loads for char length determinations. Suitable.... Shorter conditioning times may be used if the change in weight of a specimen in successive weighings made...

16 CFR 1616.5 - Test procedure.

Code of Federal Regulations, 2014 CFR

2014-01-01

... specimen holder to be used in this test method is detailed in Engineering Drawing Number 7. It is designed... hooks and weights shall be used to produce a series of loads for char length determinations. Suitable.... Shorter conditioning times may be used if the change in weight of a specimen in successive weighings made...

Roughness and compressive strength of FDM 3D printed specimens affected by acetone vapour treatment

NASA Astrophysics Data System (ADS)

Beniak, Juraj; Križan, Peter; Šooš, Ľubomír; Matúš, Miloš

2018-01-01

Rapid Prototyping technologies are the fastest growing technologies in the manufacturing of components and parts. There are many techniques which can be used with different materials and different purposes of produced part. Gradually, Rapid Prototyping systems have grown into Additive Manufacturing, because technology expansion brings faster production, improved manufactured components, and expanded palette of used materials. So now this techniques are also used for regular production of special parts, where is usual change of part design, where is necessary to produce variety of different designs and shapes. The following article deals with Fused Deposition Modelling (FDM) technology, the core of which is the manufacture models and components from thermoplastic polymers by deposition single fibres of semi-molten plastic material layer by layer. The article focuses on the results of research for testing of manufactured specimens by FDM technology. Components are modified by acetone vapour for surface smoothing. The purpose is to point out how the additional specimen treatment influence the strength properties. Presented paper shows realized experiments and measurements of compressive force on specimens and surface roughness which are influenced by acetone vapour treatment.

Test results for composite specimens and elements containing joints and cutouts

NASA Technical Reports Server (NTRS)

Sumida, P. T.; Madan, R. C.; Hawley, A. V.

1988-01-01

A program was conducted to develop the technology for joints and cutouts in a composite fuselage that meets all design requirements of a large transport aircraft for the 1990s. An advanced trijet derivative of the DC-10 was selected as the baseline aircraft. Design and analysis of a 30-foot-long composite fuselage barrel provided a realistic basis for the test effort. The primary composite material was Hexcel F584 resin on 12 K IM6 fiber, in tape and broadgoods form. Fiberglass broadgoods were used in E-glass and S-glass fiber form in the cutout region of some panels. Additionally, injection-molded chopped graphite fiber/PEEK was used for longeron-to-frame shear clips. The test effort included four groups of test specimens, beginning with coupon specimens of mono-layer and cross-piled laminates, progressing through increasingly larger and more complex specimens, and ending with two 4- by 5-foot curved fuselage side panels. One of the side panels incorporated a transverse skin splice, while the second included two cabin window cutouts.

Measurement of specimen-induced aberrations of biological samples using phase stepping interferometry.

PubMed

Schwertner, M; Booth, M J; Neil, M A A; Wilson, T

2004-01-01

Confocal or multiphoton microscopes, which deliver optical sections and three-dimensional (3D) images of thick specimens, are widely used in biology. These techniques, however, are sensitive to aberrations that may originate from the refractive index structure of the specimen itself. The aberrations cause reduced signal intensity and the 3D resolution of the instrument is compromised. It has been suggested to correct for aberrations in confocal microscopes using adaptive optics. In order to define the design specifications for such adaptive optics systems, one has to know the amount of aberrations present for typical applications such as with biological samples. We have built a phase stepping interferometer microscope that directly measures the aberration of the wavefront. The modal content of the wavefront is extracted by employing Zernike mode decomposition. Results for typical biological specimens are presented. It was found for all samples investigated that higher order Zernike modes give only a small contribution to the overall aberration. Therefore, these higher order modes can be neglected in future adaptive optics sensing and correction schemes implemented into confocal or multiphoton microscopes, leading to more efficient designs.

PRELIMINARY RESULTS OF THE AGC-4 IRRADIATION IN THE ADVANCED TEST REACTOR AND DESIGN OF AGC-5 (HTR16-18469)

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

Davenport, Michael; Petti, D. A.

The United States Department of Energy’s Advanced Reactor Technologies (ART) Program will irradiate up to six nuclear graphite creep experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The graphite experiments are being irradiated over an approximate eight year period to support development of a graphite irradiation performance data base on the new nuclear grade graphites now available for use in high temperature gas reactors. The goals of the irradiation experiments are to obtain irradiation performance data, including irradiation creep, at different temperatures and loading conditions to support design of the Very High Temperature Gasmore » Reactor (VHTR), as well as other future gas reactors. The experiments each consist of a single capsule that contain six stacks of graphite specimens, with half of the graphite specimens in each stack under a compressive load, while the other half of the specimens are not be subjected to a compressive load during irradiation. The six stacks have differing compressive loads applied to the top half of diametrically opposite pairs of specimen stacks. A seventh specimen stack in the center of the capsule does not have a compressive load. The specimens are being irradiated in an inert sweep gas atmosphere with on-line temperature and compressive load monitoring and control. There are also samples taken of the sweep gas effluent to measure any oxidation or off-gassing of the specimens that may occur during initial start-up of the experiment. The first experiment, AGC-1, started its irradiation in September 2009, and the irradiation was completed in January 2011. The second experiment, AGC-2, started its irradiation in April 2011 and completed its irradiation in May 2012. The third experiment, AGC-3, started its irradiation in late November 2012 and completed in the April of 2014. AGC-4 is currently being irradiated in the ATR. This paper will briefly discuss the preliminary irradiation results of the AGC-4 experiment, as well as the design of AGC-5.« less

Microfabricated instrument for tissue biopsy and analysis

DOEpatents

Krulevitch, Peter A.; Lee, Abraham P.; Northrup, M. Allen; Benett, William J.

1999-01-01

A microfabricated biopsy/histology instrument which has several advantages over the conventional procedures, including minimal specimen handling, smooth cutting edges with atomic sharpness capable of slicing very thin specimens (approximately 2 .mu.m or greater), micro-liter volumes of chemicals for treating the specimens, low cost, disposable, fabrication process which renders sterile parts, and ease of use. The cutter is a "cheese-grater" style design comprising a block or substrate of silicon and which uses anisotropic etching of the silicon to form extremely sharp and precise cutting edges. As a specimen is cut, it passes through the silicon cutter and lies flat on a piece of glass which is bonded to the cutter. Microchannels are etched into the glass or silicon substrates for delivering small volumes of chemicals for treating the specimen. After treatment, the specimens can be examined through the glass substrate. For automation purposes, microvalves and micropumps may be incorporated. Also, specimens in parallel may be cut and treated with identical or varied chemicals. The instrument is disposable due to its low cost and thus could replace current expensive microtome and histology equipment.

Temperature Effects on the Magnetic Properties of Silicon-Steel Sheets Using Standardized Toroidal Frame

PubMed Central

Wu, Cheng-Ju; Lin, Shih-Yu; Chou, Shang-Chin; Tsai, Chia-Yun; Yen, Jia-Yush

2014-01-01

This study designed a detachable and standardized toroidal test frame to measure the electromagnetic characteristic of toroidal laminated silicon steel specimens. The purpose of the design was to provide the measurements with standardized and controlled environment. The device also can withstand high temperatures (25–300°C) for short time period to allow high temperature tests. The accompanying driving circuit facilitates testing for high frequency (50–5,000 Hz) and high magnetic flux (0.2–1.8 T) conditions and produces both sinusoidal and nonsinusoidal test waveforms. The thickness of the stacked laminated silicon-steel sheets must be 30~31 mm, with an internal diameter of 72 mm and an outer diameter of 90 mm. With the standardized setup, it is possible to carry out tests for toroidal specimen in high temperature and high flux operation. The test results show that there is a tendency of increased iron loss under high temperature operation. The test results with various driving waveforms also provide references to the required consideration in engineering designs. PMID:25525629

Structural Efficiency and Behavior of Pristine and Notched Stitched Structure

NASA Technical Reports Server (NTRS)

Jegley, Dawn C.

2011-01-01

Two driving factors in aircraft panel design are structural efficiency and response to in-service damage. Stitching through the thickness can improve both of these considerations. Combining stitching with a post-buckling design approach can provide additional improvements. The buckling behavior of stitched structure is considered since lighter structures can be achieved if local skin buckling is allowed to occur at less than design ultimate load. Through-the-thickness stitching can suppress delamination between skin and flange, thereby allowing the structure to reliably carry load into the postbuckling range. Hat-stiffened and rod-stiffened panels in which the skin and flanges were stitched together through-the-thickness prior to curing are considered through experiment and analysis. In both types of panels no mechanical fasteners were used for the assembly. Specimens were loaded to failure in axial compression. In this study all specimens buckled in the skin between the stiffeners and continued to carry load. In addition, the behavior of panels with a severed stringer or notch are considered. Failure loads and strain distributions in the notched panel are compared to those in the unnotched panel.

Temperature effects on the magnetic properties of silicon-steel sheets using standardized toroidal frame.

PubMed

Wu, Cheng-Ju; Lin, Shih-Yu; Chou, Shang-Chin; Tsai, Chia-Yun; Yen, Jia-Yush

2014-01-01

This study designed a detachable and standardized toroidal test frame to measure the electromagnetic characteristic of toroidal laminated silicon steel specimens. The purpose of the design was to provide the measurements with standardized and controlled environment. The device also can withstand high temperatures (25-300°C) for short time period to allow high temperature tests. The accompanying driving circuit facilitates testing for high frequency (50-5,000 Hz) and high magnetic flux (0.2-1.8 T) conditions and produces both sinusoidal and nonsinusoidal test waveforms. The thickness of the stacked laminated silicon-steel sheets must be 30~31 mm, with an internal diameter of 72 mm and an outer diameter of 90 mm. With the standardized setup, it is possible to carry out tests for toroidal specimen in high temperature and high flux operation. The test results show that there is a tendency of increased iron loss under high temperature operation. The test results with various driving waveforms also provide references to the required consideration in engineering designs.

Comparative study of the wear behavior of composites for posterior restorations.

PubMed

Turssi, Cecilia P; Faraoni-Romano, Juliana J; de Menezes, Márcio; Serra, Mônica C

2007-01-01

This investigation sought to compare the abrasive wear rates of resin composites designed for posterior applications. Seventy-five specimens were fabricated with conventional hybrid (Charisma and Filtek Z250) or packable composites (Filtek P60, Solitaire II and Tetric Ceram HB), according to a randomized complete block design (n = 15). Specimens were finished and polished metallographically and subjected to abrasive wear which was performed under a normal load of 13N at a frequency of 2 Hz using a pneumatic device (MSM/Elquip) in the presence of a mucin-containing artificial saliva. Wear was quantified profilometrically in five different locations of each specimen after 1,000, 5,000, 10,000, 50,000 and after every each 50,000 through 250,000 cycles. A split-plot ANOVA showed a significant difference between the wear resistance of composites (alpha = 0.05). Tukey's test ascertained that while the composites Filtek Z250 and Charisma wore significantly less than any other of the materials tested, Tetric Ceram HB experienced the greatest wear rates. Filtek P60 and Solitaire II showed intermediate rates of material removal. The wear pattern of composites proved to be biphasic with the primary phase having the faster wear rate. In conclusion, packable resin composites may not have superior wear compared to conventional hybrid composites.

An ultra-high temperature testing instrument under oxidation environment up to 1800 °C.

PubMed

Cheng, Xiangmeng; Qu, Zhaoliang; He, Rujie; Ai, Shigang; Zhang, Rubing; Pei, Yongmao; Fang, Daining

2016-04-01

A new testing instrument was developed to measure the high-temperature constitutive relation and strength of materials under an oxidative environment up to 1800 °C. A high temperature electric resistance furnace was designed to provide a uniform temperature environment for the mechanical testing, and the temperature could vary from room temperature (RT) to 1800 °C. A set of semi-connected grips was designed to reduce the stress. The deformation of the specimen gauge section was measured by a high temperature extensometer. The measured results were acceptable compared with the results from the strain gauge method. Meanwhile, tensile testing of alumina was carried out at RT and 800 °C, and the specimens showed brittle fracture as expected. The obtained Young's modulus was in agreement with the reported value. In addition, tensile experiment of ZrB2-20%SiC ceramic was conducted at 1700 °C and the high-temperature tensile stress-strain curve was first obtained. Large plastic deformation up to 0.46% and the necking phenomenon were observed before the fracture of specimen. This instrument will provide a powerful research tool to study the high temperature mechanical property of materials under oxidation and is benefit for the engineering application of materials in aerospace field.

Lung Carcinoma Predictive Biomarker Testing by Immunoperoxidase Stains in Cytology and Small Biopsy Specimens: Advantages and Limitations.

PubMed

Zhou, Fang; Moreira, Andre L

2016-12-01

- In the burgeoning era of molecular genomics, immunoperoxidase (IPOX) testing grows increasingly relevant as an efficient and effective molecular screening tool. Patients with lung carcinoma may especially benefit from the use of IPOX because most lung carcinomas are inoperable at diagnosis and only diagnosed by small tissue biopsy or fine-needle sampling. When such small specimens are at times inadequate for molecular testing, positive IPOX results still provide actionable information. - To describe the benefits and pitfalls of IPOX in the detection of biomarkers in lung carcinoma cytology specimens and small biopsies by summarizing the currently available commercial antibodies, preanalytic variables, and analytic considerations. - PubMed. - Commercial antibodies exist for IPOX detection of aberrant protein expression due to EGFR L858R mutation, EGFR E746_A750 deletion, ALK rearrangement, ROS1 rearrangement, and BRAF V600E mutation, as well as PD-L1 expression in tumor cells. Automated IPOX protocols for ALK and PD-L1 detection were recently approved by the Food and Drug Administration as companion diagnostics for targeted therapies, but consistent interpretive criteria remain to be elucidated, and such protocols do not yet exist for other biomarkers. The inclusion of cytology specimens in clinical trials would expand patients' access to testing and treatment, yet there is a scarcity of clinical trial data regarding the application of IPOX to cytology, which can be attributed to trial designers' lack of familiarity with the advantages and limitations of cytology. The content of this review may be used to inform clinical trial design and advance IPOX validation studies.

Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.

2000-01-01

Thermo-oxidative aging produces a nonuniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hr. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and coefficient of thermal expansion (CTE) of nitrogen aged specimens were measured directly. The nitrogen-aged specimens were assumed to have the same properties as the interior material in the air-aged specimens. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

The centrifuge facility - A life sciences research laboratory for Space Station Freedom

NASA Technical Reports Server (NTRS)

Fuller, Charles A.; Johnson, Catherine C.; Hargens, Alan R.

1991-01-01

The paper describes the centrifugal facility that is presently being developed by NASA for studies aboard the Space Station Freedom on the role of gravity, or its absence, at varying intensities for varying periods of time and with multiple model systems. Special attention is given to the design of the centrifuge system, the habitats designed to hold plants and animals, the glovebox system designed for experimental manipulations of the specimens, and the service unit. Studies planned for the facility will include experiments in the following disciplines: cell and developmental biology, plant biology, regulatory physiology, musculoskeletal physiology, behavior and performance, neurosciences, cardiopulmonary physiology, and environmental health and radiation.

Thermomechanical Stress in Cryopreservation Via Vitrification With Nanoparticle Heating as a Stress-Moderating Effect.

PubMed

Eisenberg, David P; Bischof, John C; Rabin, Yoed

2016-01-01

This study focuses on thermomechanical effects in cryopreservation associated with a novel approach of volumetric heating by means on nanoparticles in an alternating electromagnetic field. This approach is studied for the application of cryopreservation by vitrification, where the crystalline phase is completely avoided-the cornerstone of cryoinjury. Vitrification can be achieved by quickly cooling the material to cryogenic storage, where ice cannot form. Vitrification can be maintained at the end of the cryogenic protocol by quickly rewarming the material back to room temperature. The magnitude of the rewarming rates necessary to maintain vitrification is much higher than the magnitude of the cooling rates that are required to achieve it in the first place. The most common approach to achieve the required cooling and rewarming rates is by exposing the specimen's surface to a temperature-controlled environment. Due to the underlying principles of heat transfer, there is a size limit in the case of surface heating beyond which crystallization cannot be prevented at the center of the specimen. Furthermore, due to the underlying principles of solid mechanics, there is a size limit beyond which thermal expansion in the specimen can lead to structural damage and fractures. Volumetric heating during the rewarming phase of the cryogenic protocol can alleviate these size limitations. This study suggests that volumetric heating can reduce thermomechanical stress, when combined with an appropriate design of the thermal protocol. Without such design, this study suggests that the level of stress may still lead to structural damage even when volumetric heating is applied. This study proposes strategies to harness nanoparticles heating in order to reduce thermomechanical stress in cryopreservation by vitrification.

Bayesian Estimation of Pneumonia Etiology: Epidemiologic Considerations and Applications to the Pneumonia Etiology Research for Child Health Study.

PubMed

Deloria Knoll, Maria; Fu, Wei; Shi, Qiyuan; Prosperi, Christine; Wu, Zhenke; Hammitt, Laura L; Feikin, Daniel R; Baggett, Henry C; Howie, Stephen R C; Scott, J Anthony G; Murdoch, David R; Madhi, Shabir A; Thea, Donald M; Brooks, W Abdullah; Kotloff, Karen L; Li, Mengying; Park, Daniel E; Lin, Wenyi; Levine, Orin S; O'Brien, Katherine L; Zeger, Scott L

2017-06-15

In pneumonia, specimens are rarely obtained directly from the infection site, the lung, so the pathogen causing infection is determined indirectly from multiple tests on peripheral clinical specimens, which may have imperfect and uncertain sensitivity and specificity, so inference about the cause is complex. Analytic approaches have included expert review of case-only results, case-control logistic regression, latent class analysis, and attributable fraction, but each has serious limitations and none naturally integrate multiple test results. The Pneumonia Etiology Research for Child Health (PERCH) study required an analytic solution appropriate for a case-control design that could incorporate evidence from multiple specimens from cases and controls and that accounted for measurement error. We describe a Bayesian integrated approach we developed that combined and extended elements of attributable fraction and latent class analyses to meet some of these challenges and illustrate the advantage it confers regarding the challenges identified for other methods. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Comparative study on stress distribution around internal tapered connection implants according to fit of cement- and screw-retained prostheses.

PubMed

Lee, Mi-Young; Heo, Seong-Joo; Park, Eun-Jin; Park, Ji-Man

2013-08-01

The aim of this study was to compare the passivity of implant superstructures by assessing the strain development around the internal tapered connection implants with strain gauges. A polyurethane resin block in which two implants were embedded served as a measurement model. Two groups of implant restorations utilized cement-retained design and internal surface of the first group was adjusted until premature contact between the restoration and the abutment completely disappeared. In the second group, only nodules detectable to the naked eye were removed. The third group employed screw-retained design and specimens were generated by computer-aided design/computer-aided manufacturing system (n=10). Four strain gauges were fixed on the measurement model mesially and distally to the implants. The strains developed in each strain gauge were recorded during fixation of specimens. To compare the difference among groups, repeated measures 2-factor analysis was performed at a level of significance of α=.05. The absolute strain values were measured to analyze the magnitude of strain. The mean absolute strain value ranged from 29.53 to 412.94 µm/m at the different strain gauge locations. According to the result of overall comparison, the cement-retained prosthesis groups exhibited significant difference. No significant difference was detected between milled screw-retained prostheses group and cement-retained prosthesis groups. Within the limitations of the study, it was concluded that the cement-retained designs do not always exhibit lower levels of stress than screw-retained designs. The internal adjustment of a cement-retained implant restoration is essential to achieve passive fit.

The Gulf Long-Term Follow-Up Study (GuLF STUDY): Biospecimen collection at enrollment.

PubMed

Engel, Lawrence S; Kwok, Richard K; Miller, Aubrey K; Blair, Aaron; Curry, Matthew D; McGrath, John A; Sandler, Dale P

2017-01-01

The 2010 Deepwater Horizon (DWH) explosion in the Gulf of Mexico led to the largest ever marine oil spill by volume. The GuLF STUDY is investigating possible adverse human health effects associated with oil spill activities. One objective of the study was to utilize biological specimens from study participants to examine spill-related adverse health effects. This study describes the methods for collecting, processing, shipping, and storing specimens during the enrollment phase of the study. GuLF STUDY participants living in Gulf States (Alabama, Florida, Louisiana, Mississippi, and eastern Texas) were eligible to complete a home visit at enrollment, one to three years after the DWH explosion. During this visit, blood, urine, toenail and hair clippings, and house dust samples were collected. Specimens were shipped overnight to a central processing laboratory in containers with cold and ambient temperature compartments. Most blood and urine specimens were then aliquoted and stored in liquid nitrogen vapor or at -80°C, with some samples stored at -20°C. A total of 11,193 participants completed a home visit, and over 99% provided at least one biospecimen. Most participants provided blood (93%), urine (99%), and toenail clippings (89%), and 40% provided hair. Nearly all participants (95%) provided house-dust samples. Most samples were received by the laboratory one (58%) or two (25%) days after collection. These biospecimens enable investigation of a range of biomarkers of spill-related adverse health effects, and possibly some biomarkers of spill-related exposures. The biospecimen collection, handling, and storage protocols were designed to maximize current and future scientific value within logistical and budgetary constraints and might serve as a template for future studies conducted in similar time-critical and geographically dispersed settings.

Effect of Impact Damage and Open Hole on Compressive Strength of Hybrid Composite Laminates

NASA Technical Reports Server (NTRS)

Hiel, Clement; Brinson, H. F.

1993-01-01

Impact damage tolerance is a frequently listed design requirement for composites hardware. The effect of impact damage and open hole size on laminate compressive strength was studied on sandwich beam specimens which combine CFRP-GFRP hybrid skins and a syntactic foam core. Three test specimen configurations have been investigated for this study. The first two were sandwich beams which were loaded in pure bending (by four point flexure). One series had a skin damaged by impact, and the second series had a circular hole machined through one of the skins. The reduction of compressive strength with increasing damage (hole) size was compared. Additionally a third series of uniaxially loaded open hole compression coupons were tested to generate baseline data for comparison with both series of sandwich beams.

Influence of Cr and W alloying on the fiber-matrix interfacial shear strength in cast and directionally solidified sapphire NiAl composites

NASA Technical Reports Server (NTRS)

Asthana, R.; Tiwari, R.; Tewari, S. N.

1995-01-01

Sapphire-reinforced NiAl matrix composites with chromium or tungsten as alloying additions were synthesized using casting and zone directional solidification (DS) techniques and characterized by a fiber pushout test as well as by microhardness measurements. The sapphire-NiAl(Cr) specimens exhibited an interlayer of Cr rich eutectic at the fiber-matrix interface and a higher interfacial shear strength compared to unalloyed sapphire-NiAl specimens processed under identical conditions. In contrast, the sapphire-NiAl(W) specimens did not show interfacial excess of tungsten rich phases, although the interfacial shear strength was high and comparable to that of sapphire-NiAl(Cr). The postdebond sliding stress was higher in sapphire-NiAl(Cr) than in sapphire-NiAl(W) due to interface enrichment with chromium particles. The matrix microhardness progressively decreased with increasing distance from the interface in both DS NiAl and NiAl(Cr) specimens. The study highlights the potential of casting and DS techniques to improve the toughness and strength of NiAl by designing dual-phase microstructures in NiAl alloys reinforced with sapphire fibers.

Design and application of a quasistatic crush test fixture for investigating scale effects in energy absorbing composite plates

NASA Astrophysics Data System (ADS)

Lavoie, J. Andre; Morton, John

1993-07-01

A crush test fixture for measuring energy absorption of flat plate specimens from an earlier study was redesigned to eliminate the problem of binding of the load transfer platen with the guide posts. Further modifications were to increase the stroke, and combine the two scaled text fixtures into one. This new crush text fixture was shown to produce load-displacement histories exhibiting well developed sustained crushing loads over long strokes. An experimental study was conducted on two material systems: AS4/3502 graphite/epoxy, and a hybrid AS4-Kevlar/3502 composite. The effect of geometric scaling of specimen size, the effect of ply level and sublaminate-level scaling of the stacking sequence of the full scale specimens, and the effect of trigger mechanism on the energy absorption capability were investigated. The new crush test fixture and flat plate specimens produced peak and sustained crushing loads that were lower than obtained with the old crush text fixture. The trigger mechanism used influenced the specific sustained crushing stress (SSCS). The results indicated that to avoid any reduction in the SSCS when scaling from the 1/2 scale to full scale specimen size, the sublaminate-level scaling approach should be used, in agreement with experiments on tubes. The use of Kevlar in place of the graphite 45 deg plies was not as effective a means for supporting and containing the 0 deg graphite plies for rushing of flat plates and resulted in a drop in the SSCS. This result did not correlate with that obtained for tubes.

Design and application of a quasistatic crush test fixture for investigating scale effects in energy absorbing composite plates. M.S. Thesis

NASA Technical Reports Server (NTRS)

Lavoie, J. Andre; Morton, John

1993-01-01

A crush test fixture for measuring energy absorption of flat plate specimens from an earlier study was redesigned to eliminate the problem of binding of the load transfer platen with the guide posts. Further modifications were to increase the stroke, and combine the two scaled text fixtures into one. This new crush text fixture was shown to produce load-displacement histories exhibiting well developed sustained crushing loads over long strokes. An experimental study was conducted on two material systems: AS4/3502 graphite/epoxy, and a hybrid AS4-Kevlar/3502 composite. The effect of geometric scaling of specimen size, the effect of ply level and sublaminate-level scaling of the stacking sequence of the full scale specimens, and the effect of trigger mechanism on the energy absorption capability were investigated. The new crush test fixture and flat plate specimens produced peak and sustained crushing loads that were lower than obtained with the old crush text fixture. The trigger mechanism used influenced the specific sustained crushing stress (SSCS). The results indicated that to avoid any reduction in the SSCS when scaling from the 1/2 scale to full scale specimen size, the sublaminate-level scaling approach should be used, in agreement with experiments on tubes. The use of Kevlar in place of the graphite 45 deg plies was not as effective a means for supporting and containing the 0 deg graphite plies for rushing of flat plates and resulted in a drop in the SSCS. This result did not correlate with that obtained for tubes.

Development and validation of an ELISA kit for the detection of ricin toxins from biological specimens and environmental samples.

PubMed

Chen, Hsiao Ying; Tran, Hung; Foo, Ling Yann; Sew, Tracey Wenhui; Loke, Weng Keong

2014-08-01

Ricin is a toxin that can be easily extracted from seeds of Ricinus communis plants. Ricin is considered to be a major bio-threat as it can be freely and easily acquired in large quantities. A deliberate release of such toxin in civilian populations would very likely overwhelm existing public health systems, resulting in public fear and social unrest. There is currently no commercially available or FDA-approved prophylaxis such as vaccines, or therapeutic antitoxins or antidotes, available for ricin intoxication. Patient treatment is typically supportive care based on symptoms, often designed to reinforce the body's natural response. This paper describes the development and validation of a robust ELISA test kit, which can be used to screen for ricin in biological specimens such as whole blood and faeces. Faecal specimens are shown in this study to have better diagnostic sensitivity and a wider diagnostic window compared to whole blood. From these results, it is concluded that faeces is the most suitable clinical specimen for diagnosis of ricin poisoning via the oral route. The ELISA test kit can also detect ricin in environmental samples. An advantage of this ELISA kit over other commercial off-the-shelf (COTS) detection kits currently on the market that are developed to screen environmental samples only is its ability to diagnose ricin poisoning from clinical specimens as well as detect ricin from environmental samples.

Apparatus for cutting elastomeric materials

NASA Technical Reports Server (NTRS)

Corbett, A. B.

1974-01-01

Sharp thin cutting edge is held in head of milling machine designed for metal working. Controls of machine are used to position cutting edge in same plane as vibrating specimen. Controls then are operated, making blade come into contact with specimen, to cut it into shapes and sizes desired. Cut surfaces appear mirror-smooth; vibrating mechanism causes no visible striations.

An analysis of blood specimen container leakage.

PubMed Central

Lewis, S M; Wardle, J M

1978-01-01

Procedures have been designed to test specimen containers for leakage, using blood and aqueous fluorescein solution as indicators. They have been used in a trial evaluation of a number of commercially available containers intended for medical specimens. Glass bijou bottles, evacuated container systems, and several types of plastic container showed no significant leakage rate with either blood or aqueous solution when they were tested at room temperature, but a large proportion of the plastic containers leaked after being subjected to -20 degrees. C. These would thus be suitable and satisfactory for blood count specimens but not for specimens of serum and other body fluids, which are usually stored frozen. With all types of container tested there was spontaneous discharge of contents (blood or aqueous solution) on opening in a proportion of them; thus no container at present available seems to be entirely free from hazard. PMID:711921

Edgeless composite laminate specimen for static and fatigue testing

NASA Technical Reports Server (NTRS)

Liber, T.; Daniel, I. M.

1978-01-01

The influence of edge effects on the tensile properties of angle-ply laminate composites can be eliminated by using edgeless (round tubular) specimens. However, uniaxial tests with such specimens, static and fatigue, have been generally unsuccessful because of the differential Poisson effect between the test section and the grips. An edgeless cylindrical specimen, developed to circumvent these difficulties, is examined in the present paper. It is a flattened tube consisting of two flat sides connected by curved sections. It can be handled much like the standard flat coupon. The flat ends of the specimen are provided with crossplied fiberglass gripping tabs, the same as used for flat test coupons. As part of the tabbing, the hollow ends must be plugged with inserts to prevent crushing of the ends. A special insert design was developed to minimize detrimental Poisson effects ordinarily introduced by inserts.

Ultrasound Transmission Times in Biologically Deteriorated Wood

Treesearch

Christopher Adam Senalik; Robert J. Ross; Rodney DeGroot

2015-01-01

The use of a variety of stress wave transmission techniques for the in-service condition assessment of deteriorated wood is well documented. This paper summarizes results from an extensive study designed to examine the relationship between ultrasound transmission times and the deterioration of exposed wood. Two hundred seventy (270) southern pine lumber specimens were...

Home-based versus clinic-based specimen collection in the management of Chlamydia trachomatis and Neisseria gonorrhoeae infections.

PubMed

Fajardo-Bernal, Luisa; Aponte-Gonzalez, Johanna; Vigil, Patrick; Angel-Müller, Edith; Rincon, Carlos; Gaitán, Hernando G; Low, Nicola

2015-09-29

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) are the most frequent causes of bacterial sexually transmitted infections (STIs). Management strategies that reduce losses in the clinical pathway from infection to cure might improve STI control and reduce complications resulting from lack of, or inadequate, treatment. To assess the effectiveness and safety of home-based specimen collection as part of the management strategy for Chlamydia trachomatis and Neisseria gonorrhoeae infections compared with clinic-based specimen collection in sexually-active people. We searched the Cochrane Sexually Transmitted Infections Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS on 27 May 2015, together with the World Health Organization International Clinical Trials Registry (ICTRP) and ClinicalTrials.gov. We also handsearched conference proceedings, contacted trial authors and reviewed the reference lists of retrieved studies. Randomized controlled trials (RCTs) of home-based compared with clinic-based specimen collection in the management of C. trachomatis and N. gonorrhoeae infections. Three review authors independently assessed trials for inclusion, extracted data and assessed risk of bias. We contacted study authors for additional information. We resolved any disagreements through consensus. We used standard methodological procedures recommended by Cochrane. The primary outcome was index case management, defined as the number of participants tested, diagnosed and treated, if test positive. Ten trials involving 10,479 participants were included. There was inconclusive evidence of an effect on the proportion of participants with index case management (defined as individuals tested, diagnosed and treated for CT or NG, or both) in the group with home-based (45/778, 5.8%) compared with clinic-based (51/788, 6.5%) specimen collection (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.60 to 1.29; 3 trials, I² = 0%, 1566 participants, moderate quality). Harms of home-based specimen collection were not evaluated in any trial. All 10 trials compared the proportions of individuals tested. The results for the proportion of participants completing testing had high heterogeneity (I² = 100%) and were not pooled. We could not combine data from individual studies looking at the number of participants tested because the proportions varied widely across the studies, ranging from 30% to 96% in home group and 6% to 97% in clinic group (low-quality evidence). The number of participants with positive test was lower in the home-based specimen collection group (240/2074, 11.6%) compared with the clinic-based group (179/967, 18.5%) (RR 0.72, 95% CI 0.61 to 0.86; 9 trials, I² = 0%, 3041 participants, moderate quality). Home-based specimen collection could result in similar levels of index case management for CT or NG infection when compared with clinic-based specimen collection. Increases in the proportion of individuals tested as a result of home-based, compared with clinic-based, specimen collection are offset by a lower proportion of positive results. The harms of home-based specimen collection compared with clinic-based specimen collection have not been evaluated. Future RCTs to assess the effectiveness of home-based specimen collection should be designed to measure biological outcomes of STI case management, such as proportion of participants with negative tests for the relevant STI at follow-up.

A study of process parameters on workpiece anisotropy in the laser engineered net shaping (LENSTM) process

NASA Astrophysics Data System (ADS)

Chandra, Shubham; Rao, Balkrishna C.

2017-06-01

The process of laser engineered net shaping (LENSTM) is an additive manufacturing technique that employs the coaxial flow of metallic powders with a high-power laser to form a melt pool and the subsequent deposition of the specimen on a substrate. Although research done over the past decade on the LENSTM processing of alloys of steel, titanium, nickel and other metallic materials typically reports superior mechanical properties in as-deposited specimens, when compared to the bulk material, there is anisotropy in the mechanical properties of the melt deposit. The current study involves the development of a numerical model of the LENSTM process, using the principles of computational fluid dynamics (CFD), and the subsequent prediction of the volume fraction of equiaxed grains to predict process parameters required for the deposition of workpieces with isotropy in their properties. The numerical simulation is carried out on ANSYS-Fluent, whose data on thermal gradient are used to determine the volume fraction of the equiaxed grains present in the deposited specimen. This study has been validated against earlier efforts on the experimental studies of LENSTM for alloys of nickel. Besides being applicable to the wider family of metals and alloys, the results of this study will also facilitate effective process design to improve both product quality and productivity.

Development and implementation of a custom integrated database with dashboards to assist with hematopathology specimen triage and traffic

PubMed Central

Azzato, Elizabeth M.; Morrissette, Jennifer J. D.; Halbiger, Regina D.; Bagg, Adam; Daber, Robert D.

2014-01-01

Background: At some institutions, including ours, bone marrow aspirate specimen triage is complex, with hematopathology triage decisions that need to be communicated to downstream ancillary testing laboratories and many specimen aliquot transfers that are handled outside of the laboratory information system (LIS). We developed a custom integrated database with dashboards to facilitate and streamline this workflow. Methods: We developed user-specific dashboards that allow entry of specimen information by technologists in the hematology laboratory, have custom scripting to present relevant information for the hematopathology service and ancillary laboratories and allow communication of triage decisions from the hematopathology service to other laboratories. These dashboards are web-accessible on the local intranet and accessible from behind the hospital firewall on a computer or tablet. Secure user access and group rights ensure that relevant users can edit or access appropriate records. Results: After database and dashboard design, two-stage beta-testing and user education was performed, with the first focusing on technologist specimen entry and the second on downstream users. Commonly encountered issues and user functionality requests were resolved with database and dashboard redesign. Final implementation occurred within 6 months of initial design; users report improved triage efficiency and reduced need for interlaboratory communications. Conclusions: We successfully developed and implemented a custom database with dashboards that facilitates and streamlines our hematopathology bone marrow aspirate triage. This provides an example of a possible solution to specimen communications and traffic that are outside the purview of a standard LIS. PMID:25250187

Laboratory systems integration: robotics and automation.

PubMed

Felder, R A

1991-01-01

Robotic technology is going to have a profound impact on the clinical laboratory of the future. Faced with increased pressure to reduce health care spending yet increase services to patients, many laboratories are looking for alternatives to the inflexible or "fixed" automation found in many clinical analyzers. Robots are being examined by many clinical pathologists as an attractive technology which can adapt to the constant changes in laboratory testing. Already, laboratory designs are being altered to accommodate robotics and automated specimen processors. However, the use of robotics and computer intelligence in the clinical laboratory is still in its infancy. Successful examples of robotic automation exist in several laboratories. Investigators have used robots to automate endocrine testing, high performance liquid chromatography, and specimen transportation. Large commercial laboratories are investigating the use of specimen processors which combine the use of fixed automation and robotics. Robotics have also reduced the exposure of medical technologists to specimens infected with viral pathogens. The successful examples of clinical robotics applications were a result of the cooperation of clinical chemists, engineers, and medical technologists. At the University of Virginia we have designed and implemented a robotic critical care laboratory. Initial clinical experience suggests that robotic performance is reliable, however, staff acceptance and utilization requires continuing education. We are also developing a robotic cyclosporine which promises to greatly reduce the labor costs of this analysis. The future will bring lab wide automation that will fully integrate computer artificial intelligence and robotics. Specimens will be transported by mobile robots. Specimen processing, aliquotting, and scheduling will be automated.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental exposure effects on composite materials for commercial aircraft

NASA Technical Reports Server (NTRS)

Hoffman, D. J.

1978-01-01

Activities reported include completion of the program design tasks, resolution of a high fiber volume problem and resumption of specimen fabrication, fixture fabrication, and progress on the analysis methodology and definition of the typical aircraft environment. Program design activities including test specimens, specimen holding fixtures, flap-track fairing tailcones, and ground exposure racks were completed. The problem experienced in obtaining acceptable fiber volume fraction results on two of the selected graphite epoxy material systems was resolved with an alteration to the bagging procedure called out in BAC 5562. The revised bagging procedure, involving lower numbers of bleeder plies, produces acceptable results. All required laminates for the contract have now been laid up and cured. Progress in the area of analysis methodology has been centered about definition of the environment that a commercial transport aircraft undergoes. The selected methodology is analagous to fatigue life assessment.

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 ...

Design, analysis and test verification of advanced encapsulation systems

NASA Technical Reports Server (NTRS)

Garcia, A.; Minning, C.

1982-01-01

Analytical models were developed to perform optical, thermal, electrical and structural analyses on candidate encapsulation systems. Qualification testing, specimens of various types, and a finalized optimum design are projected.

Long-Term In Vivo Electromechanical Reshaping for Auricular Reconstruction in the New Zealand White Rabbit Model

PubMed Central

Badran, Karam W.; Manuel, Cyrus T.; Loy, Anthony Chin; Conderman, Christian; Yau, Yuk Yee; Lin, Jennifer; Tjoa, Tjoson; Su, Erica; Protsenko, Dmitriy; Wong, Brian J. F.

2016-01-01

Objectives/Hypothesis To demonstrate the dosimetry effect of electromechanical reshaping (EMR) on cartilage shape change, structural integrity, cellular viability, and remodeling of grafts in an in vivo long-term animal model. Study Design Animal study. Methods A subperichondrial cartilaginous defect was created within the base of the pinna of 31 New Zealand white rabbits. Autologous costal cartilage grafts were electromechanically reshaped to resemble the rabbit auricular base framework and mechanically secured into the pinna base defect. Forty-nine costal cartilage specimens (four control and 45 experimental) successfully underwent EMR using a paired set of voltage-time combinations and survived for 6 or 12 weeks. Shape change was measured, and specimens were analyzed using digital imaging, tissue histology, and confocal microscopy with LIVE-DEAD viability assays. Results Shape change was proportional to charge transfer in all experimental specimens (P <.01) and increased with voltage. All experimental specimens contoured to the auricular base. Focal cartilage degeneration and fibrosis was observed where needle electrodes were inserted, ranging from 2.2 to 3.9 mm. The response to injury increased with increasing charge transfer and survival duration. Conclusions EMR results in appropriate shape change in cartilage grafts with chondrocyte injury highly localized. These studies suggest that elements of auricular reconstruction may be feasible using EMR. Extended survival periods and further optimization of voltage-time pairs are necessary to evaluate the long-term effects and shape-change potential of EMR. PMID:25779479

Actively cooled plate fin sandwich structural panels for hypersonic aircraft

NASA Technical Reports Server (NTRS)

Smith, L. M.; Beuyukian, C. S.

1979-01-01

An unshielded actively cooled structural panel was designed for application to a hypersonic aircraft. The design was an all aluminum stringer-stiffened platefin sandwich structure which used a 60/40 mixture of ethylene glycol/water as the coolant. Eight small test specimens of the basic platefin sandwich concept and three fatigue specimens from critical areas of the panel design was fabricated and tested (at room temperature). A test panel representative of all features of the panel design was fabricated and tested to determine the combined thermal/mechanical performance and structural integrity of the system. The overall findings are that; (1) the stringer-stiffened platefin sandwich actively cooling concept results in a low mass design that is an excellent contender for application to a hypersonic vehicle, and (2) the fabrication processes are state of the art but new or modified facilities are required to support full scale panel fabrication.

Chemotoxicity Recovery of Mitochondria in Non-Hodgkin Lymphoma Resulting in Minimal Residual Disease

PubMed Central

Kusao, Ian; Agsalda, Melissa; Troelstrup, David; Villanueva, Nicolas; Shiramizu, Bruce

2009-01-01

Background The mechanisms responsible for resistant disease or recurrence of non-Hodgkin lymphoma (NHL) in children cover a wide spectrum from drug resistance to genetic mutations. A unique mechanism suggesting the role of mitochondria as the key energy source is studied following a clinical observation where pediatric Burkitt lymphoma (BL) specimens from patients on therapy were found to have increased copies of mitochondria DNA (mtDNA) in specimens which were shown to be positive for minimal residual disease and/or persistent disease (MRD/PD). This study hypothesized that the mitochondria play an important role in a cell’s recovery from toxicity via a compensatory increase in mtDNA. Procedure BL specimens with MRD/PD were assayed for mtDNA. An in vitro model was then designed using Ramos cell lines by exposing the lymphoma cells to varying concentrations of doxorubicin and vincristine for 1 hr; and allowing for recovery in culture over 7 days. DNA was extracted from aliquots over several days to determine mtDNA copy numbers by real-time polymerase chain reaction (PCR). Results Increased mtDNA copy numbers were found in clinical specimens with MRD/PD as well as in recovering Ramos cells from chemotoxicity. Conclusions The recovering lymphoma cells from the chemotoxic effects appeared to compensate by increasing mtDNA content, which may contribute to the clinical residual or resistant disease in some cases of childhood BL. PMID:18322926

Application of carbon FRP for fatigue strengthening of old steel structures

NASA Astrophysics Data System (ADS)

Vůjtěch, J.; Ryjáček, P.; Vovesný, M.

2017-02-01

The traffic requirements on the existing infrastructure are rising still. This coupled with its age puts a strain on it. This is especially problematic for old steel bridges. Higher and more frequent loads will lead to development of fatigue damage to those structures. This causes an issue for the infrastructure owners as the existing methods of repair are difficult, time consuming and expensive. So there is a need to find some easier alternatives. One of such can be the use of carbon fibre reinforced polymers (CFRP). They are being successfully used for repairs and strengthening of concrete structures however their use with steel is still relatively new. The purpose of this work is to establish how does a deteriorated steel reinforced with CFRP behave under fatigue loading. To test this a series of experiments was designed. With the help of a preliminary numerical study the dimensions of the specimens and the applied loading was established. There are two sets of specimens. With both we are using mild steel and each set has different level of surface deterioration (corrosion pits or corrosion holes). The specimens are reinforced using hand laid wet layup composites. They are subjected to fatigue loading and the difference between the fatigue life reinforced and unreinforced specimens is observed. Based on the preliminary study, it is expected, that the reinforcement will prolong the life expectancy by half.

Toothbrushing before or after an acidic challenge to minimize tooth wear? An in situ/ex vivo study.

PubMed

Wiegand, Annette; Egert, Sebastian; Attin, Thomas

2008-02-01

To evaluate whether patients should be advised to perform toothbrushing before or after an acidic challenge to minimize enamel and dentin wear by brushing abrasion. The study was a two-period crossover design (A and B, each 14 days) in which three enamel and dentin specimens were fixed in intraoral appliances of 10 volunteers. The following regimens were performed three times a day with at least 4 hours in between: A: 20-second brushing treatment in an automatic brushing machine, 5 minutes intraoral exposure of the specimens, extraoral erosion of enamel and dentin specimens for 40 seconds or B: Extraoral erosion for 40 seconds, 5 minutes intraoral exposure of the specimens, 20-second brushing treatment in an automatic brushing machine. Enamel and dentin loss at the end of each 14-day regimen was assessed by profilometry and statistically analyzed by t-test. For all volunteers, mean enamel and dentin wear was significantly lower when brushing treatment was performed before erosion (A: enamel: 2.3 +/- 1.0 microm, dentin: 4.1 +/- 1.6 microm) than when brushing was applied after erosion (B: enamel: 6.4 +/- 3.0 microm, dentin: 15.3 +/- 6.8 microm). It was concluded that patients awaiting an erosive attack should perform toothbrushing prior to rather than after an acidic challenge to minimize enamel and dentin wear.

Advanced Test Reactor National Scientific User Facility (ATR NSUF) Monthly ReportJanuary 2015

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

Soelberg, Renae

2015-01-01

Highlights; Mike Worley and Shane Johnson visited INL Jan. 22 for an NSUF strategy discussion; Rory Kennedy attended a NSLS-2 Beamline Advisory Team meeting at Brookhaven; Provided a final cost estimate to the NSUF Program Office in support of the NEET/NSUF proposal, “Metal-ceramic and metal-metal composites for extreme radiation and temperature environment: An in situ interface stability and mechanical behavior study by high energy x-ray diffraction with a synchrotron probe.”; Assisted in the development of conceptual designs and performed a preliminary thermal hydraulic analysis for two NEET/NSUF proposals. The challenge for both experiments is to provide high (>1000 C andmore » up to 1600 C)) specimen temperatures in a small space (0.5" diameter ATR Outboard A-position) without overheating the coolant. Several designs were analyzed and found to be feasible, although detailed design and analysis will be required after the projects are awarded; and A single USU TEM specimen is packaged and awaiting shipment from MFC to CAES. Once at CAES, SEM, TEM and LEAP analysis will be performed. Professor Ban has requested additional sub-samples to be made to take back to his laboratory at USU for thermal diffusivity studies.« less

Study of the Effect of Swelling on Irradiation Assisted Stress Corrosion Cracking

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

Teysseyre, Sebastien Paul

2016-09-01

This report describes the methodology used to study the effect of swelling on the crack growth rate of an irradiation-assisted stress corrosion crack that is propagating in highly irradiated stainless steel 304 material irradiated to 33 dpa in the Experimental Breeder Reactor-II. The material selection, specimens design, experimental apparatus and processes are described. The results of the current test are presented.

Methodology for Mechanical Property Testing on Fuel Cladding Using an Expanded Plug Wedge Test

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

Wang, Jy-An John; Jiang, Hao

To determine the tensile properties of irradiated fuel cladding in a hot cell, a simple test was developed at ORNL and is described fully in US Patent Application 20060070455, Expanded plug method for developing circumferential mechanical properties of tubular materials. This method is designed for testing fuel rod cladding ductility in a hot cell utilizing an expandable plug to stretch a small ring of irradiated cladding material. The specimen strain is determined using the measured diametrical expansion of the ring. This method removes many complexities associated with specimen preparation and testing. The advantages are the simplicity of measuring the testmore » component assembly in the hot cell and the direct measurement of specimen strain. It was also found that cladding strength could be determined from the test results. The basic approach of this test method is to apply an axial compressive load to a cylindrical plug of polyurethane (or other materials) fitted inside a short ring of the test material to achieve radial expansion of the specimen. The diameter increase of the specimen is used to calculate the circumferential strain accrued during the test. The other two basic measurements are total applied load and amount of plug compression (extension). A simple procedure is used to convert the load circumferential strain data from the ring tests into material pseudo-stress-strain curves. However, several deficiencies exist in this expanded-plug loading ring test, which will impact accuracy of test results and introduce potential shear failure of the specimen due to inherited large axial compressive stress from the expansion plug test. First of all, the highly non-uniform stress and strain distribution resulted in the gage section of the clad. To ensure reliable testing and test repeatability, the potential for highly non-uniform stress distribution or displacement/strain deformation has to be eliminated at the gage section of the specimen. Second, significant compressive stresses were induced by clad bending deformation due to a clad bulging effect (or the barreling effect). The barreling effect caused very large localized shear stress in the clad and left testing material at a high risk of shear failure. The above combined effects will result in highly non-conservative predictions both in strength and ductility of the tested clad, and the associated mechanical properties as well. To overcome/mitigate the mentioned deficiencies associated with the current expansion plug test, systematic studies have been conducted. Through detailed parameter investigation on specific geometry designs, careful filtering of material for the expansion plug, as well as adding newly designed parts to the testing system, a method to reconcile the potential non-conservatism embedded in the expansion plug test system has been discovered. A modified expansion plug testing protocol has been developed based on the method. In order to closely resemble thin-wall theory, a general procedure was also developed to determine the hoop stress in the tested ring specimen. A scaling factor called -factor is defined to correlate the ring load P into hoop stress . , = . The generated stress-strain curve agrees very well with tensile test data in both the elastic and plastic regions.« less

Fracture Probability of MEMS Optical Devices for Space Flight Applications

NASA Technical Reports Server (NTRS)

Fettig, Rainer K.; Kuhn, Jonathan L.; Moseley, S. Harvey; Kutyrev, Alexander S.; Orloff, Jon

1999-01-01

A bending fracture test specimen design is presented for thin elements used in optical devices for space flight applications. The specimen design is insensitive to load position, avoids end effect complications, and can be used to measure strength of membranes less than 2 microns thick. The theoretical equations predicting stress at failure are presented, and a detailed finite element model is developed to validate the equations for this application. An experimental procedure using a focused ion beam machine is outlined, and results from preliminary tests of 1.9 microns thick single crystal silicon are presented. These tests are placed in the context of a methodology for the design and evaluation of mission critical devices comprised of large arrays of cells.

Acousto-optic Imaging System for In-situ Measurement of the High Temperature Distribution in Micron-size Specimens

NASA Astrophysics Data System (ADS)

Machikhin, Alexander S.; Zinin, Pavel V.; Shurygin, Alexander V.

We developed a unique acousto-optic imaging system for in-situ measurement of high temperature distribution on micron-size specimens. The system was designed to measure temperature distribution inside minerals and functional material phases subjected to high pressure and high temperatures in a diamond anvil cell (DAC) heated by a high powered laser.

The use of impact force as a scale parameter for the impact response of composite laminates

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Poe, C. C., Jr.

1992-01-01

The building block approach is currently used to design composite structures. With this approach, the data from coupon tests is scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low velocity impacts where the mass of the impacter is large and the size of the specimen is small. For large mass impacts of moderately thick (0.35 to 0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large mass test results can be applied directly to other plates of the same size.

A mechanical microcompressor for high resolution imaging of motile specimens

PubMed Central

Zinskie, Jessica A.; Shribak, Michael; Bruist, Michael F.; Aufderheide, Karl J.; Janetopoulos, Chris

2015-01-01

In order to obtain fine details in 3 dimensions (3D) over time, it is critical for motile biological specimens to be appropriately immobilized. Of the many immobilization options available, the mechanical microcompressor offers many benefits. Our device, previously described, achieves gentle flattening of a cell, allowing us to image finely detailed structures of numerous organelles and physiological processes in living cells. We have imaged protozoa and other small metazoans using differential interference contrast (DIC) microscopy, orientation-independent (OI) DIC, and real-time birefringence imaging using a video-enhanced polychromatic polscope. We also describe an enhancement of our previous design by engineering a new device where the coverslip mount is fashioned onto the top of the base; so the entire apparatus is accessible on top of the stage. The new location allows for easier manipulation of the mount when compressing or releasing a specimen on an inverted microscope. Using this improved design, we imaged immobilized bacteria, yeast, paramecia, and nematode worms and obtained an unprecedented view of cell and specimen details. A variety of microscopic techniques were used to obtain high resolution images of static and dynamic cellular and physiological events. PMID:26192819

A mechanical microcompressor for high resolution imaging of motile specimens.

PubMed

Zinskie, Jessica A; Shribak, Michael; Bruist, Michael F; Aufderheide, Karl J; Janetopoulos, Chris

2015-10-01

In order to obtain fine details in 3 dimensions (3D) over time, it is critical for motile biological specimens to be appropriately immobilized. Of the many immobilization options available, the mechanical microcompressor offers many benefits. Our device, previously described, achieves gentle flattening of a cell, allowing us to image finely detailed structures of numerous organelles and physiological processes in living cells. We have imaged protozoa and other small metazoans using differential interference contrast (DIC) microscopy, orientation-independent (OI) DIC, and real-time birefringence imaging using a video-enhanced polychromatic polscope. We also describe an enhancement of our previous design by engineering a new device where the coverslip mount is fashioned onto the top of the base; so the entire apparatus is accessible on top of the stage. The new location allows for easier manipulation of the mount when compressing or releasing a specimen on an inverted microscope. Using this improved design, we imaged immobilized bacteria, yeast, paramecia, and nematode worms and obtained an unprecedented view of cell and specimen details. A variety of microscopic techniques were used to obtain high resolution images of static and dynamic cellular and physiological events. Copyright © 2015 Elsevier Inc. All rights reserved.

The use of impact force as a scale parameter for the impact response of composite laminates

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Poe, C. C., Jr.

1992-01-01

The building block approach is currently used to design composite structures. With this approach, the data from coupon tests are scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low-velocity impacts where the mass of the impacter is large, and the size of the specimen is small. For large-mass impacts of moderately thick (0.35-0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large-mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large-mass test results can be applied directly to other plates of the same thickness.

Environmental chamber for in situ dynamic control of temperature and relative humidity during x-ray scattering

NASA Astrophysics Data System (ADS)

Salas-de la Cruz, David; Denis, Jeffrey G.; Griffith, Matthew D.; King, Daniel R.; Heiney, Paul A.; Winey, Karen I.

2012-02-01

We have designed, constructed, and evaluated an environmental chamber that has in situ dynamic control of temperature (25 to 90 °C) and relative humidity (0% to 95%). The compact specimen chamber is designed for x-ray scattering in transmission with an escape angle of 2θ = ±30°. The specimen chamber is compatible with a completely evacuated system such as the Rigaku PSAXS system, in which the specimen chamber is placed inside a larger evacuated chamber (flight path). It is also compatible with x-ray systems consisting of evacuated flight tubes separated by small air gaps for sample placement. When attached to a linear motor (vertical displacement), the environmental chamber can access multiple sample positions. The temperature and relative humidity inside the specimen chamber are controlled by passing a mixture of dry and saturated gas through the chamber and by heating the chamber walls. Alternatively, the chamber can be used to control the gaseous environment without humidity. To illustrate the value of this apparatus, we have probed morphology transformations in Nafion® membranes and a polymerized ionic liquid as a function of relative humidity in nitrogen.

Microscope basics.

PubMed

Sluder, Greenfield; Nordberg, Joshua J

2013-01-01

This chapter provides information on how microscopes work and discusses some of the microscope issues to be considered in using a video camera on the microscope. There are two types of microscopes in use today for research in cell biology-the older finite tube-length (typically 160mm mechanical tube length) microscopes and the infinity optics microscopes that are now produced. The objective lens forms a magnified, real image of the specimen at a specific distance from the objective known as the intermediate image plane. All objectives are designed to be used with the specimen at a defined distance from the front lens element of the objective (the working distance) so that the image formed is located at a specific location in the microscope. Infinity optics microscopes differ from the finite tube-length microscopes in that the objectives are designed to project the image of the specimen to infinity and do not, on their own, form a real image of the specimen. Three types of objectives are in common use today-plan achromats, plan apochromats, and plan fluorite lenses. The concept of mounting video cameras on the microscope is also presented in the chapter. Copyright © 2003 Elsevier Inc. All rights reserved.

A snail in the long tail: a new Plekocheilus species collected by the ‘Comisión Científica del Pacífico’ (Mollusca, Gastropoda, Amphibulimidae)

PubMed Central

Breure, Abraham S. H.; Araujo, Rafael

2015-01-01

Abstract Among the historical collection gathered by the ‘Comisión Científica del Pacífico’ during 1862–1865, type material was found of one of the species described on the basis of the material collected shortly afterwards. Inspection of the types revealed that only one specimen may be considered as type material of Bulimus aristaceus Crosse, 1869; this specimen is now designated as the lectotype. The other specimens are described as a new species, Plekocheilus (Plekocheilus) cecepeus. PMID:26312021

[Anatomy study on micro transverse flap pedicled with superfical palmar branch of radial artery from palmar wrist].

PubMed

Zhao, Min; Tian, Dehu; Shao, Xinzhong; Li, Dacun; Li, Jianfeng; Liu, Jingda; Zhao, Liang; Li, Hailei; Wang, Xiaolei; Zhang, Wentong; Wu, Jinying; Yuan, Zuoxiong

2013-07-01

To study the anatomical basis of micro transverse flap pedicled with the superfical palmar branch of radial artery from the palmar wrist for using this free flap to repair soft tissue defect of the finger. Thirty-eight fresh upper limb specimens (22 males and 16 females; aged 26-72 years with an average of 36 years; at left and right sides in 19 limbs respectively) were dissected and observed under operating microscope. Two specimens were made into casting mould of artery with bones, and 2 specimens were injected with red emulsion in radial artery. Thirty-four specimens were injected with 1% gentian violet solution in the superfical palmar branch of the radial artery. A transverse oval flap in the palmar wrist was designed, the axis of the flap was the distal palmar crease. The origin, distribution, and anastomosis of the superfical palmar branch of the radial artery were observed. The superficial palmar branch of the radial artery was constantly existed, it usually arises from the main trunk of the radial artery, 1.09-3.60 cm to proximal styloid process of radius. There were about 2-5 branches between the origin and the tubercle of scaphoid bone. The origin diameter was 1.00-3.00 mm, and the distal diameter at the styloid process of radius was 1.00-2.90 mm. The venous return of flap passed through 2 routes, and the innervations of the flap mainly from the palmar cutaneous branch of the median nerve. The area of the flap was 4 cm x 2 cm-6 cm x 2 cm. The origin and courses of the superficial palmar branch of the radial artery is constant, and its diameter is similar to that of the digital artery. A transverse oval flap pedicled with the superfical palmar branch of radial artery in the palmar wrist can be designed to repair defects of the finger.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system.

PubMed

Shinohara, Ayano; Taira, Yohsuke; Sakihara, Michino; Sawase, Takashi

2018-01-01

Objective The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system. Material and Methods Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive). Results PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths. Conclusion A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study.

Effects of three silane primers and five adhesive agents on the bond strength of composite material for a computer-aided design and manufacturing system

PubMed Central

2018-01-01

Abstract Objective The objective of this study was to evaluate the effects of combinations of silane primers and adhesive agents on the bond strength of a composite block for a computer-aided design and manufacturing system. Material and Methods Three silane primers [Clearfil Ceramic Primer (CP), Super-Bond PZ Primer (PZ), and GC Ceramic Primer II (GP)] were used in conjunction with five adhesive agents [G-Premio Bond (P-Bond), Repair Adhe Adhesive (R-Adhesive), Super-Bond D-Liner Dual (SB-Dual), Super-Bond C&B (SB-Self), and SB-Dual without tributylborane derivative (SB-Light)]. The surface of a composite block (Gradia Block) was ground with silicon carbide paper. After treatment with a silane primer, a adhesive agent was applied to each testing specimen. The specimens were then bonded with a light-curing resin composite. After 24 h, the shear bond strength values were determined and compared using a post hoc test (α=0.05, n=8/group). We also prepared control specimens without primer (No primer) and/or without adhesive agent (No adhesive). Results PZ/SB-Dual and GP/SB-Dual presented the highest bond strength, followed by GP/P-Bond, CP/SB-Dual, CP/R-Adhesive, No primer/SB-Dual, GP/R-Adhesive, CP/P-Bond, No primer/R-Adhesive, PZ/R-Adhesive, CP/SB-Self, PZ/P-Bond, PZ/SB-Self, and GP/SB-Self in descending order of bond strength. No primer/P-Bond, No primer/SB-Self, and all specimens in the SB-Light and No adhesive groups presented the lowest bond strengths. Conclusion A dual-curing adhesive agent (SB-Dual) containing a tributylborane derivative in combination with a silane primer (GP or PZ) presents a greater bond strength between the composite block and the repairing resin composite than the comparators used in the study. PMID:29742254

Fabrication and Probabilistic Fracture Strength Prediction of High-Aspect-Ratio Single Crystal Silicon Carbide Microspecimens With Stress Concentration

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Evans, Laura J.; Jadaan, Osama M.; Sharpe, William N., Jr.; Beheim, Glenn M.; Trapp, Mark A.

2005-01-01

Single crystal silicon carbide micro-sized tensile specimens were fabricated with deep reactive ion etching (DRIE) in order to investigate the effect of stress concentration on the room-temperature fracture strength. The fracture strength was defined as the level of stress at the highest stressed location in the structure at the instant of specimen rupture. Specimens with an elliptical hole, a circular hole, and without a hole (and hence with no stress concentration) were made. The average fracture strength of specimens with a higher stress concentration was larger than the average fracture strength of specimens with a lower stress concentration. Average strength of elliptical-hole, circular-hole, and without-hole specimens was 1.53, 1.26, and 0.66 GPa, respectively. Significant scatter in strength was observed with the Weibull modulus ranging between 2 and 6. No fractographic examination was performed but it was assumed that the strength controlling flaws originated from etching grooves along the specimen side-walls. The increase of observed fracture strength with increasing stress concentration was compared to predictions made with the Weibull stress-integral formulation by using the NASA CARES/Life code. In the analysis isotropic material and fracture behavior was assumed - hence it was not a completely rigorous analysis. However, even with these assumptions good correlation was achieved for the circular-hole specimen data when using the specimen data without stress concentration as a baseline. Strength was over predicted for the elliptical-hole specimen data. Significant specimen-to-specimen dimensional variation existed in the elliptical-hole specimens due to variations in the nickel mask used in the etching. To simulate the additional effect of the dimensional variability on the probabilistic strength response for the single crystal specimens the ANSYS Probabilistic Design System (PDS) was used with CARES/Life.

Blood-collection device for trace and ultra-trace metal specimens evaluated.

PubMed

Moyer, T P; Mussmann, G V; Nixon, D E

1991-05-01

We evaluated the evacuated phlebotomy tube designed specifically for trace metal analysis by Sherwood Medical Co. Pools of human serum containing known concentrations of aluminum, arsenic, calcium, cadmium, copper, chromium, iron, lead, magnesium, manganese, mercury, selenium, and zinc were exposed to the tube and rubber stopper for defined periods ranging from 5 min to 24 h. Analysis for each element was performed in a randomized fashion under rigidly controlled conditions by use of standard electrothermal atomization atomic absorption spectroscopy, inductively coupled plasma atomic emission spectroscopy, and cold vapor atomic absorption spectrometry. In addition, for comparative purposes, we collected blood samples from normal volunteers by use of ultra-clean polystyrene phlebotomy syringes as well as standard evacuated phlebotomy tubes. We conclude that, except for lead, there was no significant contribution of any trace element studied from the evaluated tube and stopper to the serum. Because whole blood is the usual specimen for lead testing, the observation of a trace amount of lead in this tube designed for serum collection is trivial.

Evaluation of refractory-metal-clad uranium nitride and uranium dioxide fuel pins after irradiation for times up to 10 450 hours at 990 C

NASA Technical Reports Server (NTRS)

Bowles, K. J.; Gluyas, R. E.

1975-01-01

The effects of some materials variables on the irradiation performance of fuel pins for a lithium-cooled space power reactor design concept were examined. The variables studied were UN fuel density, fuel composition, and cladding alloy. All pins were irradiated at about 990 C in a thermal neutron environment to the design fuel burnup. An 85-percent dense UN fuel gave the best overall results in meeting the operational goals. The T-111 cladding on all specimens was embrittled, possibly by hydrogen in the case of the UN fuel and by uranium and oxygen in the case of the UO2 fuel. Tests with Cb-1Zr cladding indicate potential use of this cladding material. The UO2 fueled specimens met the operational goals of less than 1 percent cladding strain, but other factors make UO2 less attractive than low-density UN for the contemplated space power reactor use.

Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope.

PubMed

Wu, J S; Kim, A M; Bleher, R; Myers, B D; Marvin, R G; Inada, H; Nakamura, K; Zhang, X F; Roth, E; Li, S Y; Woodruff, T K; O'Halloran, T V; Dravid, Vinayak P

2013-05-01

A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Design of a superconducting volume coil for magnetic resonance microscopy of the mouse brain

NASA Astrophysics Data System (ADS)

Nouls, John C.; Izenson, Michael G.; Greeley, Harold P.; Johnson, G. Allan

2008-04-01

We present the design process of a superconducting volume coil for magnetic resonance microscopy of the mouse brain at 9.4 T. The yttrium barium copper oxide coil has been designed through an iterative process of three-dimensional finite-element simulations and validation against room temperature copper coils. Compared to previous designs, the Helmholtz pair provides substantially higher B1 homogeneity over an extended volume of interest sufficiently large to image biologically relevant specimens. A custom-built cryogenic cooling system maintains the superconducting probe at 60 ± 0.1 K. Specimen loading and probe retuning can be carried out interactively with the coil at operating temperature, enabling much higher through-put. The operation of the probe is a routine, consistent procedure. Signal-to-noise ratio in a mouse brain increased by a factor ranging from 1.1 to 2.9 as compared to a room-temperature solenoid coil optimized for mouse brain microscopy. We demonstrate images encoded at 10 × 10 × 20 μm for an entire mouse brain specimen with signal-to-noise ratio of 18 and a total acquisition time of 16.5 h, revealing neuroanatomy unseen at lower resolution. Phantom measurements show an effective spatial resolution better than 20 μm.

Design of a superconducting volume coil for magnetic resonance microscopy of the mouse brain.

PubMed

Nouls, John C; Izenson, Michael G; Greeley, Harold P; Johnson, G Allan

2008-04-01

We present the design process of a superconducting volume coil for magnetic resonance microscopy of the mouse brain at 9.4T. The yttrium barium copper oxide coil has been designed through an iterative process of three-dimensional finite-element simulations and validation against room temperature copper coils. Compared to previous designs, the Helmholtz pair provides substantially higher B(1) homogeneity over an extended volume of interest sufficiently large to image biologically relevant specimens. A custom-built cryogenic cooling system maintains the superconducting probe at 60+/-0.1K. Specimen loading and probe retuning can be carried out interactively with the coil at operating temperature, enabling much higher through-put. The operation of the probe is a routine, consistent procedure. Signal-to-noise ratio in a mouse brain increased by a factor ranging from 1.1 to 2.9 as compared to a room-temperature solenoid coil optimized for mouse brain microscopy. We demonstrate images encoded at 10x10x20mum for an entire mouse brain specimen with signal-to-noise ratio of 18 and a total acquisition time of 16.5h, revealing neuroanatomy unseen at lower resolution. Phantom measurements show an effective spatial resolution better than 20mum.

Coded aperture coherent scatter spectral imaging for assessment of breast cancers: an ex-vivo demonstration

NASA Astrophysics Data System (ADS)

Spencer, James R.; Carter, Joshua E.; Leung, Crystal K.; McCall, Shannon J.; Greenberg, Joel A.; Kapadia, Anuj J.

2017-03-01

A Coded Aperture Coherent Scatter Spectral Imaging (CACSSI) system was developed in our group to differentiate cancer and healthy tissue in the breast. The utility of the experimental system was previously demonstrated using anthropomorphic breast phantoms and breast biopsy specimens. Here we demonstrate CACSSI utility in identifying tumor margins in real time using breast lumpectomy specimens. Fresh lumpectomy specimens were obtained from Surgical Pathology with the suspected cancerous area designated on the specimen. The specimens were scanned using CACSSI to obtain spectral scatter signatures at multiple locations within the tumor and surrounding tissue. The spectral reconstructions were matched with literature form-factors to classify the tissue as cancerous or non-cancerous. The findings were then compared against pathology reports to confirm the presence and location of the tumor. The system was found to be capable of consistently differentiating cancerous and healthy regions in the breast with spatial resolution of 5 mm. Tissue classification results from the scanned specimens could be correlated with pathology results. We now aim to develop CACSSI as a clinical imaging tool to aid breast cancer assessment and other diagnostic purposes.

Irradiation of Wrought FeCrAl Tubes in the High Flux Isotope Reactor

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

Linton, Kory D.; Field, Kevin G.; Petrie, Christian M.

The Advanced Fuels Campaign within the Nuclear Technology Research and Development program of the Department of Energy Office of Nuclear Energy is seeking to improve the accident tolerance of light water reactors. Alumina-forming ferritic alloys (e.g., FeCrAl) are one of the leading candidate materials for fuel cladding to replace traditional zirconium alloys because of the superior oxidation resistance of FeCrAl. However, there are still some unresolved questions regarding irradiation effects on the microstructure and mechanical properties of FeCrAl at end-of-life dose levels. In particular, there are concerns related to irradiation-induced embrittlement of FeCrAl alloys due to secondary phase formation. Tomore » address this issue, Oak Ridge National Laboratory has developed a new experimental design to irradiate shortened cladding tube specimens with representative 17×17 array pressurized water reactor diameter and thickness in the High Flux Isotope Reactor (HFIR) under relevant temperatures (300–350°C). Post-irradiation examination will include studies of dimensional change, microstructural changes, and mechanical performance. This report briefly summarizes the capsule design concept and the irradiation test matrix for six rabbit capsules. Each rabbit contains two FeCrAl alloy tube specimens. The specimens include Generation I and Generation II FeCrAl alloys with varying processing conditions, Cr concentrations, and minor alloying elements. The rabbits were successfully assembled, welded, evaluated, and delivered to the HFIR along with a complete quality assurance fabrication package. Pictures of the rabbit assembly process and detailed dimensional inspection of select specimens are included in this report. The rabbits were inserted into HFIR starting in cycle 472 (May 2017).« less

On the Effects of Modeling As-Manufactured Geometry: Toward Digital Twin

NASA Technical Reports Server (NTRS)

Cerrone, Albert; Hochhalter, Jacob; Heber, Gerd; Ingraffea, Anthony

2014-01-01

Asimple, nonstandardized material test specimen,which fails along one of two different likely crack paths, is considered herein.The result of deviations in geometry on the order of tenths of amillimeter, this ambiguity in crack pathmotivates the consideration of asmanufactured component geometry in the design, assessment, and certification of structural systems.Herein, finite elementmodels of as-manufactured specimens are generated and subsequently analyzed to resolve the crack-path ambiguity. The consequence and benefit of such a "personalized" methodology is the prediction of a crack path for each specimen based on its as-manufactured geometry, rather than a distribution of possible specimen geometries or nominal geometry.The consideration of as-manufactured characteristics is central to the Digital Twin concept. Therefore, this work is also intended to motivate its development.

Unit Plants, First Trial Materials, Inspection Set.

ERIC Educational Resources Information Center

Australian Science Education Project, Toorak, Victoria.

The Australian Science Education Project is producing materials designed for use in grades 7-10 of Australian schools. This is the first trial version of a unit introducing the study of plants. The section to be completed by all pupils, contained in the first of the student workbooks, emphasizes observation of specimens on school grounds and on…

Experimental validation of a new heterogeneous mechanical test design

NASA Astrophysics Data System (ADS)

Aquino, J.; Campos, A. Andrade; Souto, N.; Thuillier, S.

2018-05-01

Standard material parameters identification strategies generally use an extensive number of classical tests for collecting the required experimental data. However, a great effort has been made recently by the scientific and industrial communities to support this experimental database on heterogeneous tests. These tests can provide richer information on the material behavior allowing the identification of a more complete set of material parameters. This is a result of the recent development of full-field measurements techniques, like digital image correlation (DIC), that can capture the heterogeneous deformation fields on the specimen surface during the test. Recently, new specimen geometries were designed to enhance the richness of the strain field and capture supplementary strain states. The butterfly specimen is an example of these new geometries, designed through a numerical optimization procedure where an indicator capable of evaluating the heterogeneity and the richness of strain information. However, no experimental validation was yet performed. The aim of this work is to experimentally validate the heterogeneous butterfly mechanical test in the parameter identification framework. For this aim, DIC technique and a Finite Element Model Up-date inverse strategy are used together for the parameter identification of a DC04 steel, as well as the calculation of the indicator. The experimental tests are carried out in a universal testing machine with the ARAMIS measuring system to provide the strain states on the specimen surface. The identification strategy is accomplished with the data obtained from the experimental tests and the results are compared to a reference numerical solution.

Perinatal Specimens of Saurolophus angustirostris (Dinosauria: Hadrosauridae), from the Upper Cretaceous of Mongolia

PubMed Central

Dewaele, Leonard; Tsogtbaatar, Khishigjav; Barsbold, Rinchen; Garcia, Géraldine; Stein, Koen; Escuillié, François; Godefroit, Pascal

2015-01-01

Background The Late Cretaceous Nemegt Formation, Gobi Desert, Mongolia has already yielded abundant and complete skeletons of the hadrosaur Saurolophus angustirostris, from half-grown to adult individuals. Methodology/Principal Findings Herein we describe perinatal specimens of Saurolophus angustirostris, associated with fragmentary eggshell fragments. The skull length of these babies is around 5% that of the largest known S. angustirostris specimens, so these specimens document the earliest development stages of this giant hadrosaur and bridge a large hiatus in our knowledge of the ontogeny of S. angustirostris. Conclusions/Significance The studied specimens are likely part of a nest originally located on a riverbank point bar. The perinatal specimens were buried by sediment carried by the river current presumably during the wet summer season. Perinatal bones already displayed diagnostic characters for Saurolophus angustirostris, including premaxillae with a strongly reflected oral margin and upturned premaxillary body in lateral aspect. The absence of a supracranial crest and unfused halves of the cervical neural arches characterize the earliest stages in the ontogeny of S. angustirostris. The eggshell fragments associated with the perinatal individuals can be referred to the Spheroolithus oogenus and closely resemble those found in older formations (e.g. Barun Goyot Fm in Mongolia) or associated with more basal hadrosauroids (Bactrosaurus-Gilmoreosaurus in the Iren Dabasu Fm, Inner Mongolia, China). This observation suggests that the egg microstructure was similar in basal hadrosauroids and more advanced saurolophines. Competing Interests One of the authors (FE) is employed by the commercial organization Eldonia. Eldonia provided support in the form of a salary for FE, but did not have any additional role or influence in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and it does not alter the authors’ adherence to all the PLoS ONE policies on sharing data and materials. PMID:26466354

Effect of five commercial mouth rinses on the microhardness of a nanofilled resin composite restorative material: An in vitro study

PubMed Central

Jyothi, KN; Crasta, Shanol; Venugopal, P

2012-01-01

Aim and Objectives: This in vitro study was designed to comparatively evaluate the effect of five commercial mouth rinses on the micro hardness of a nanofilled resin based restorative material. Materials and Methods: Fifty specimens of resin composite material (Filtek Z350XT, 3M ESPE, St.Paul, MN USA) were prepared and immersed in artificial saliva for 24 h. The base line micro hardness of specimens was recorded using Vicker's micro hardness tester (MMT – X7 Matsuzawa, Japan). The specimens were randomly distributed into five groups, each containing 10 specimens (n=10) as follows – Group I Listerine (alcohol based), Group II Periogard (alcohol based), Group III Colgate plax (alcohol based), Group IV C- prev (alcohol free), Group V Hiora(alcohol free). The specimens were immersed in 20 ml of mouth rinses and incubated for 24 h at 37°C. The post immersion micro hardness values of the specimens were recorded and the data was tabulated for statistical analysis. Kruskal–Wallis test was used for inter group comparison followed by pair wise comparison of groups using Mann–Whitney U test. The level of significance was set at P=0.05. Results: Significant reduction in the mean VHN (Vicker's micro hardness number) was observed in all the groups after exposure to the tested mouth rinses (P<0.01) and the reduction in mean VHN values were as follows: Group I 12.09, Group II 3.42, Group II 1.51, Group IV 1.03, Group V 0.57. Inter group comparison showed statistically significant reduction in micro hardness in Groups I and II compared to all other groups with P<0.001. There was no significant difference between Groups III, IV and V. Conclusion: All the mouth rinses showed a reduction in the microhardness of nanofilled resin composite material with listerine (Group I) containing maximum amount of alcohol, showing highest reduction in micro hardness value. PMID:22876004

Prediction of resilient modulus from soil index properties

DOT National Transportation Integrated Search

2004-11-01

Subgrade soil characterization in terms of Resilient Modulus (MR) has become crucial for pavement design. For a new design, MR values are generally obtained by conducting repeated load triaxial tests on reconstituted/undisturbed cylindrical specimens...

Risk of Anterior Cruciate Ligament Fatigue Failure Is Increased by Limited Internal Femoral Rotation During In Vitro Repeated Pivot Landings

PubMed Central

Beaulieu, Mélanie L.; Wojtys, Edward M.; Ashton-Miller, James A.

2015-01-01

Background A reduced range of hip internal rotation is associated with increased peak anterior cruciate ligament (ACL) strain and risk for injury. It is unknown, however, whether limiting the available range of internal femoral rotation increases the susceptibility of the ACL to fatigue failure. Hypothesis Risk of ACL failure is significantly greater in female knee specimens with a limited range of internal femoral rotation, smaller femoral-ACL attachment angle, and smaller tibial eminence volume during repeated in vitro simulated single-leg pivot landings. Study Design Controlled laboratory study. Methods A custom-built testing apparatus was used to simulate repeated single-leg pivot landings with a 4×-body weight impulsive load that induces knee compression, knee flexion, and internal tibial torque in 32 paired human knee specimens from 8 male and 8 female donors. These test loads were applied to each pair of specimens, in one knee with limited internal femoral rotation and in the contralateral knee with femoral rotation resisted by 2 springs to simulate the active hip rotator muscles’ resistance to stretch. The landings were repeated until ACL failure occurred or until a minimum of 100 trials were executed. The angle at which the ACL originates from the femur and the tibial eminence volume were measured on magnetic resonance images. Results The final Cox regression model (P = .024) revealed that range of internal femoral rotation and sex of donor were significant factors in determining risk of ACL fatigue failure. The specimens with limited range of internal femoral rotation had a failure risk 17.1 times higher than did the specimens with free rotation (P = .016). The female knee specimens had a risk of ACL failure 26.9 times higher than the male specimens (P = .055). Conclusion Limiting the range of internal femoral rotation during repetitive pivot landings increases the risk of an ACL fatigue failure in comparison with free rotation in a cadaveric model. Clinical Relevance Screening for restricted internal rotation at the hip in ACL injury prevention programs as well as in individuals with ACL injuries and/or reconstructions is warranted. PMID:26122384

Final Report: Posttest Analysis of Omega II Optical Specimens

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

Newlander, C D; Fisher, J H

Preliminary posttest analyses have been completed on optical specimens exposed during the Omega II test series conducted on 14 July 2006. The Omega Facility, located at the Laboratory for Laser Energetics (LLE) at the University of Rochester was used to produce X-ray environments through the interaction of intense pulsed laser radiation upon germanium-loaded silica aerogels. The optical specimen testing was supported by GH Systems through experiment design, pre- and post-test analyses, specimen acquisition, and overall technical experience. The test specimens were fabricated and characterized by Surface Optics Corporation (SOC), San Diego, CA and were simple protected gold coatings on silicamore » substrates. Six test specimens were exposed, five filtered with thin beryllium foil filters, and one unfiltered which was exposed directly to the raw environment. The experimental objectives were: (1) demonstrate that tests of optical specimens could be performed at the Omega facility; (2) evaluate the use and survivability of beryllium foil filters as a function of thickness; (3) obtain damage data on optical specimens which ranged from no damage to damage; (4) correlate existing thermal response models with the damage data; (5) evaluate the use of the direct raw environment upon the specimen response and the ability/desirability to conduct sensitive optical specimen tests using the raw environment; and (6) initiate the development of a protocol for performing optical coatings/mirror tests. This report documents the activities performed by GH Systems in evaluating and using the environments provided by LLNL, the PUFFTFT analyses performed using those environments, and the calculated results compared to the observed and measured posttest data.« less

Self-collected versus clinician-collected sampling for sexually transmitted infections: a systematic review and meta-analysis protocol.

PubMed

Taylor, Darlene; Lunny, Carole; Wong, Tom; Gilbert, Mark; Li, Neville; Lester, Richard; Krajden, Mel; Hoang, Linda; Ogilvie, Gina

2013-10-10

Three meta-analyses and one systematic review have been conducted on the question of whether self-collected specimens are as accurate as clinician-collected specimens for STI screening. However, these reviews predate 2007 and did not analyze rectal or pharyngeal collection sites. Currently, there is no consensus on which sampling method is the most effective for the diagnosis of genital chlamydia (CT), gonorrhea (GC) or human papillomavirus (HPV) infection. Our meta-analysis aims to be comprehensive in that it will examine the evidence of whether self-collected vaginal, urine, pharyngeal and rectal specimens provide as accurate a clinical diagnosis as clinician-collected samples (reference standard). Eligible studies include both randomized and non-randomized controlled trials, pre- and post-test designs, and controlled observational studies. The databases that will be searched include the Cochrane Database of Systematic Reviews, Web of Science, Database of Abstracts of Reviews of Effects (DARE), EMBASE and PubMed/Medline. Data will be abstracted independently by two reviewers using a standardized pre-tested data abstraction form. Heterogeneity will be assessed using the Q2 test. Sensitivity and specificity estimates with 95% confidence intervals as well as negative and positive likelihood ratios will be pooled and weighted using random effects meta-analysis, if appropriate. A hierarchical summary receiver operating characteristics curve for self-collected specimens will be generated. This synthesis involves a meta-analysis of self-collected samples (urine, vaginal, pharyngeal and rectal swabs) versus clinician-collected samples for the diagnosis of CT, GC and HPV, the most prevalent STIs. Our systematic review will allow patients, clinicians and researchers to determine the diagnostic accuracy of specimens collected by patients compared to those collected by clinicians in the detection of chlamydia, gonorrhea and HPV.

How Many Cultures Are Necessary to Identify Pathogens in the Management of Total Hip and Knee Arthroplasty Infections?

PubMed

Gandhi, Rikesh; Silverman, Edward; Courtney, Paul M; Lee, Gwo-Chin

2017-09-01

Identification of the infecting organism is critical to the successful management of deep prosthetic joint infections about the hip and the knee. However, the number of culture specimens and which culture specimens are best to identify these organisms is unknown. We evaluated 113 consecutive patients with infected total hip and total knee arthroplasties and correlated the type of culture specimen and number of specimens taken during surgery to the likelihood of a positive culture result. From these data, we subsequently developed a model to maximize culture yield at the time of surgical intervention. After exclusions, 74 patients meeting the Musculoskeletal Infection Society criteria were left for final analysis. From this cohort, 63 of 74 patients had a positive culture result (85%). The odds of a fluid culture result being positive was 35 of 47 (0.75), whereas the likelihood of tissue cultures yielding a positive result was 164 of 245 (0.67; P = .313). The sample designated "best culture" specimen was the only culture with a positive result in 1 of 48 cases in which a best culture was identified. The optimal number of cultures needed to yield a positive test result was 4 (specificity = 0.61 and sensitivity = 0.63). Increasing the number of samples increases sensitivity but reduces specificity. A minimum of 4 tissue cultures from representative areas is necessary to maximize the chance of identifying the infecting organism during management of the infected total hip and total knee arthroplasties. The designation of the best culture specimen for additional testing is arbitrary and may not be clinically efficacious. Copyright © 2017 Elsevier Inc. All rights reserved.

Design of a 300-kV gas environmental transmission electron microscope equipped with a cold field emission gun.

PubMed

Isakozawa, Shigeto; Nagaoki, Isao; Watabe, Akira; Nagakubo, Yasuhira; Saito, Nobuhiro; Matsumoto, Hiroaki; Zhang, Xiao Feng; Taniguchi, Yoshifumi; Baba, Norio

2016-08-01

A new in situ environmental transmission electron microscope (ETEM) was developed based on a 300 kV TEM with a cold field emission gun (CFEG). Particular caution was taken in the ETEM design to assure uncompromised imaging and analytical performance of the TEM. Because of the improved pumping system between the gun and column, the vacuum of CFEG was largely improved and the probe current was sufficiently stabilized to operate without tip flashing for 2-3 h or longer. A high brightness of 2.5 × 10(9) A/cm(2) sr was measured at 300 kV, verifying the high quality of the CFEG electron beam. A specially designed gas injection-heating holder was used in the in situ TEM study at elevated temperatures with or without gas around the TEM specimen. Using this holder in a 10 Pa gas atmosphere and specimen temperatures up to 1000°C, high-resolution ETEM performance and analysis were achieved. © The Author 2016. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

In vitro study of the effect of three hydrogen peroxide concentrations on the corrosion behavior and surface topography of alumina-reinforced dental ceramic.

PubMed

Abu-Eittah, Manal R; Mandour, Mona H

2011-10-01

This in vitro investigation studied the effect of three hydrogen peroxide (HP) concentrations (30%, 35%, 38% v/v) at two time intervals (1 and 2 hours) on the corrosion behavior and surface topography of a dental ceramic. A total of 62 Vitadur Alpha discs were constructed following manufacturer instructions. Specimens were divided into four main groups (n = 8). Group 1 (control): specimens were immersed in 4% acetic acid for 18 hours at 80°C. Groups 2, 3, and 4: specimens were immersed in 30%, 35%, and 38% HP concentrations, respectively. Each of the three groups was divided into two subgroups (a and b) according to the immersion time (1 and 2 hours, respectively). Specimens of subgroup a were further immersed in 4% acetic acid for 18 hours at 80°C and were designated as subgroup c. The corrosion behavior of the ceramic specimens were tested by solution analysis using the atomic absorption method, weight loss percent, and corrosion rate. Surface topography was investigated by surface roughness (Ra) measurements and scanning electron microscopy (SEM). Results were statistically analyzed. There was a significant increase for ions leached with the increase in time of immersion for all ions at 35% and 38% HP, while at 30% HP, ions of K(+) , Al(3+) , and Si(4+) did not increase significantly with time. The results also showed that at a fixed time of immersion, all ions released were dependent on the increase of HP concentration except for Al(3+) ions (p < 0.05). The combined treatment of specimens with HP followed by acetic acid had a significant effect on the increase of ions leached (p < 0.05). The surface roughness values for all specimens increased significantly with time of immersion as well as with the increase in concentration of HP (p < 0.05). These results were confirmed with SEM. The amount of released ions is directly proportional to HP concentration and time of immersion. Specimens exposed to both HP and acetic acid showed increased weight loss and a higher corrosion rate than those exposed to acetic acid only. Surface roughness values were time and HP concentration dependent. © 2011 by The American College of Prosthodontists.

Advancement of X-Ray Microscopy Technology and its Application to Metal Solidification Studies

NASA Technical Reports Server (NTRS)

Kaukler, William F.; Curreri, Peter A.

1996-01-01

The technique of x-ray projection microscopy is being used to view, in real time, the structures and dynamics of the solid-liquid interface during solidification. By employing a hard x-ray source with sub-micron dimensions, resolutions of 2 micrometers can be obtained with magnifications of over 800 X. Specimen growth conditions need to be optimized and the best imaging technologies applied to maintain x-ray image resolution, contrast and sensitivity. It turns out that no single imaging technology offers the best solution and traditional methods like radiographic film cannot be used due to specimen motion (solidification). In addition, a special furnace design is required to permit controlled growth conditions and still offer maximum resolution and image contrast.

Comparison of contemporary occipitocervical instrumentation techniques with and without C1 lateral mass screws.

PubMed

Wolfla, Christopher E; Salerno, Simon A; Yoganandan, Narayan; Pintar, Frank A

2007-09-01

This study was designed to test the kinematic properties of three occiput-C2 instrumentation constructs with and without supplemental rigid C1 fixation. The results are compared with intact specimens and with constructs incorporating contemporary cabling techniques. Five unembalmed human cadaver specimens underwent range of motion (ROM) testing in the intact condition, followed by destabilization with odontoid osteotomy. Destabilized specimens then underwent ROM testing with each of seven occipitocervical instrumentation constructs, all incorporating occipital screws: C1 and C2 sublaminar cables with cable connectors, C2 pars screws +/- C1 lateral mass screws, C2 lamina screws +/- C1 lateral mass screws, and C1-C2 transarticular screws +/- C1 lateral mass screws. All seven constructs demonstrated significantly lower ROM in all loading modes than intact specimens (P < 0.05). With a single exception, the addition of C1 lateral mass screws to the screw-based constructs produced no significant change in ROM in any of the loading modes. Compared with intact specimens, constructs anchored by C1-C2 transarticular screws demonstrated the greatest decrease in ROM, and those anchored by sublaminar cables demonstrated the least decrease in ROM. Any of the tested screw-based constructs are likely to provide adequate support for the patient with an unstable craniocervical junction. Therefore, the choice of construct should be based on anatomic considerations. The routine incorporation of C1 lateral mass screws into occipitocervical instrumentation constructs does not seem necessary.

Experimental Investigation on the Fatigue Mechanical Properties of Intermittently Jointed Rock Models Under Cyclic Uniaxial Compression with Different Loading Parameters

NASA Astrophysics Data System (ADS)

Liu, Yi; Dai, Feng; Dong, Lu; Xu, Nuwen; Feng, Peng

2018-01-01

Intermittently jointed rocks, widely existing in many mining and civil engineering structures, are quite susceptible to cyclic loading. Understanding the fatigue mechanism of jointed rocks is vital to the rational design and the long-term stability analysis of rock structures. In this study, the fatigue mechanical properties of synthetic jointed rock models under different cyclic conditions are systematically investigated in the laboratory, including four loading frequencies, four maximum stresses, and four amplitudes. Our experimental results reveal the influence of the three cyclic loading parameters on the mechanical properties of jointed rock models, regarding the fatigue deformation characteristics, the fatigue energy and damage evolution, and the fatigue failure and progressive failure behavior. Under lower loading frequency or higher maximum stress and amplitude, the jointed specimen is characterized by higher fatigue deformation moduli and higher dissipated hysteresis energy, resulting in higher cumulative damage and lower fatigue life. However, the fatigue failure modes of jointed specimens are independent of cyclic loading parameters; all tested jointed specimens exhibit a prominent tensile splitting failure mode. Three different crack coalescence patterns are classified between two adjacent joints. Furthermore, different from the progressive failure under static monotonic loading, the jointed rock specimens under cyclic compression fail more abruptly without evident preceding signs. The tensile cracks on the front surface of jointed specimens always initiate from the joint tips and then propagate at a certain angle with the joints toward the direction of maximum compression.

Structural Characterization and Gas Reactions of Small Metal Particles by High Resolution In-situ TEM and TED. [Transmission Electron Microscopy and Transmission Electron Diffraction

NASA Technical Reports Server (NTRS)

Heinemann, K.

1985-01-01

A commercial electron microscope with flat-plate upper pole piece configuration of the objective lens and top entry specimen introduction was modified to obtain 5 x 10 to the minus 10th power mbar pressure at the site of the specimen while maintaining the convenience of a specimen airlock system that allows operation in the 10 to the 10th power mbar range within 15 minutes after specimen change. The specimen chamber contains three wire evaporation sources, a specimen heater, and facilities for oxygen or hydrogen plasma treatment to clean as-introduced specimens. Evacuation is achieved by dural differential pumping, with fine entrance and exit apertures for the electron beam. With the microscope operating at .000001 mbar, the first differential pumping stage features a high-speed cryopump operating in a stainless steel chamber that can be mildly baked and reaches 1 x 10 to the minus 8th power mbar. The second stage, containing the evaporation sources and a custom ionization gauge within 10 cm from the specimen, is a rigorously uncompromised all-metal uhv-system that is bakable to above 200 C throughout and is pumped with an 80-liter ion pump. Design operating pressures and image quality (resolution of metal particles smaller than 1 nm in size) was achieved.

Calcified lesion modeling for excimer laser ablation

NASA Astrophysics Data System (ADS)

Scott, Holly A.; Archuleta, Andrew; Splinter, Robert

2009-06-01

Objective: Develop a representative calcium target model to evaluate penetration of calcified plaque lesions during atherectomy procedures using 308 nm Excimer laser ablation. Materials and Methods: An in-vitro model representing human calcified plaque was analyzed using Plaster-of-Paris and cement based composite materials as well as a fibrinogen model. The materials were tested for mechanical consistency. The most likely candidate(s) resulting from initial mechanical and chemical screening was submitted for ablation testing. The penetration rate of specific multi-fiber catheter designs and a single fiber probe was obtained and compared to that in human cadaver calcified plaque. The effects of lasing parameters and catheter tip design on penetration speed in a representative calcified model were verified against the results in human cadaver specimens. Results: In Plaster of Paris, the best penetration was obtained using the single fiber tip configuration operating at 100 Fluence, 120 Hz. Calcified human lesions are twice as hard, twice as elastic as and much more complex than Plaster of Paris. Penetration of human calcified specimens was highly inconsistent and varied significantly from specimen to specimen and within individual specimens. Conclusions: Although Plaster of Paris demonstrated predictable increases in penetration with higher energy density and repetition rate, it can not be considered a totally representative laser ablation model for calcified lesions. This is in part due to the more heterogeneous nature and higher density composition of cadaver intravascular human calcified occlusions. Further testing will require a more representative model of human calcified lesions.

High-Temperature Thermal Conductivity Measurement Apparatus Based on Guarded Hot Plate Method

NASA Astrophysics Data System (ADS)

Turzo-Andras, E.; Magyarlaki, T.

2017-10-01

An alternative calibration procedure has been applied using apparatus built in-house, created to optimize thermal conductivity measurements. The new approach compared to those of usual measurement procedures of thermal conductivity by guarded hot plate (GHP) consists of modified design of the apparatus, modified position of the temperature sensors and new conception in the calculation method, applying the temperature at the inlet section of the specimen instead of the temperature difference across the specimen. This alternative technique is suitable for eliminating the effect of thermal contact resistance arising between a rigid specimen and the heated plate, as well as accurate determination of the specimen temperature and of the heat loss at the lateral edge of the specimen. This paper presents an overview of the specific characteristics of the newly developed "high-temperature thermal conductivity measurement apparatus" based on the GHP method, as well as how the major difficulties are handled in the case of this apparatus, as compared to the common GHP method that conforms to current international standards.

A review of the effect of a/W ratio on fracture toughness (II) —experimental investigation in LEFM

NASA Astrophysics Data System (ADS)

Li, Qing-Fen; Fu, Yu-Dong; Xu, Xiao-Xue

2005-06-01

In part I of this series, experimental investigation in EPFM (elastic-plastic fracture mechanics) had been discussed. In this paper, experimental investigation in LEFM (linear elastic fracture mechanics) is given. Fracture toughness tests had been carried out on three different strength steels, using both through-cracked specimens with different a/W ratio and semi-elliptical cracked specimens with variable crack size and shape. Results show that the fracture toughness K IC increases with decreasing a/W when a/W<0.3 for three-point-bend specimens, and that for a/W>0.3, it is independent of a/W. Shallow crack specimens, both through-cracked and surface-cracked, gave markedly higher values than deeply notched specimens. However, the effect of crack shape on fracture toughness is negligible. Results also show that the LEFM approach to fracture is not tenable for design stresses where a c is often very small, far less than 2.5(K IC/σ y )2.

Evaluation of superplastic forming and co-diffusion bonding of Ti-6Al-4V titanium alloy expanded sandwich structures

NASA Technical Reports Server (NTRS)

Arvin, G. H.; Israeli, L.; Stolpestad, J. H.; Stacher, G. W.

1981-01-01

The application of the superplastic forming/diffusion bonding (SPF/DB) process to supersonic cruise research is investigated. The capability of an SPF/DB titanium structure to meet the structural requirements of the inner wing area of the NASA arrow-wing advanced supersonic transport design is evaluated. Selection of structural concepts and their optimization for minimum weight, SPF/DB process optimization, fabrication of representative specimens, and specimen testing and evaluation are described. The structural area used includes both upper and lower wing panels, where the upper wing panel is used for static compression strength evaluation and the lower panel, in tension, is used for fracture mechanics evaluations. The individual test specimens, cut from six large panels, consist of 39 static specimens, 10 fracture mechanics specimens, and one each full size panel for compression stability and fracture mechanics testing. Tests are performed at temperatures of -54 C (-65 F), room temperature, and 260 C (500 F).

Performance of the Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis and rifampin resistance in a low-incidence, high-resource setting.

PubMed

Rice, Jason P; Seifert, Marva; Moser, Kathleen S; Rodwell, Timothy C

2017-01-01

Performance of the Xpert MTB/RIF assay, designed to simultaneously detect Mycobacterium tuberculosis complex (MTBC) and rifampin (RIF) resistance, has been well documented in low-resource settings with high TB-incidence. However, few studies have assessed its accuracy in low TB incidence settings. We evaluated the performance of Xpert MTB/RIF using clinical sputum specimens routinely collected from suspect pulmonary TB patients over a 4-year time period in San Diego County, California. Xpert MTB/RIF results were compared to acid-fast bacilli (AFB) smear microscopy, mycobacterial culture, and phenotypic drug susceptibility testing (DST). Of 751 sputum specimens, 134 (17.8%) were MTBC culture-positive and 2 (1.5%) were multidrug-resistant (MDR). For the detection of MTBC, Xpert MTB/RIF sensitivity was 89.6% (97.7% and 74.5% in smear-positive and -negative sputa, respectively) and specificity was 97.2%; while AFB smear sensitivity and specificity were 64.9% and 77.8%, respectively. Xpert MTB/RIF detected 35 of 47 smear-negative culture-positive specimens, and excluded 124 of 137 smear-positive culture-negative specimens. Xpert MTB/RIF also correctly excluded 99.2% (121/122) of nontuberculous mycobacteria (NTM) specimens, including all 33 NTM false-positives by smear microscopy. For the detection of RIF resistance, Xpert MTB/RIF sensitivity and specificity were 100% and 98.3%, respectively. Our findings demonstrate that Xpert MTB/RIF is able to accurately detect MTBC and RIF resistance in routinely collected respiratory specimens in a low TB-incidence setting, with comparable performance to that achieved in high-incidence settings; and suggest that under these conditions the assay has particular utility in detecting smear-negative TB cases, excluding smear-positive patients without MTBC disease, and differentiating MTBC from NTM.

Performance of the Xpert MTB/RIF assay for the diagnosis of pulmonary tuberculosis and rifampin resistance in a low-incidence, high-resource setting

PubMed Central

Rice, Jason P.; Moser, Kathleen S.; Rodwell, Timothy C.

2017-01-01

Performance of the Xpert MTB/RIF assay, designed to simultaneously detect Mycobacterium tuberculosis complex (MTBC) and rifampin (RIF) resistance, has been well documented in low-resource settings with high TB-incidence. However, few studies have assessed its accuracy in low TB incidence settings. We evaluated the performance of Xpert MTB/RIF using clinical sputum specimens routinely collected from suspect pulmonary TB patients over a 4-year time period in San Diego County, California. Xpert MTB/RIF results were compared to acid-fast bacilli (AFB) smear microscopy, mycobacterial culture, and phenotypic drug susceptibility testing (DST). Of 751 sputum specimens, 134 (17.8%) were MTBC culture-positive and 2 (1.5%) were multidrug-resistant (MDR). For the detection of MTBC, Xpert MTB/RIF sensitivity was 89.6% (97.7% and 74.5% in smear-positive and -negative sputa, respectively) and specificity was 97.2%; while AFB smear sensitivity and specificity were 64.9% and 77.8%, respectively. Xpert MTB/RIF detected 35 of 47 smear-negative culture-positive specimens, and excluded 124 of 137 smear-positive culture-negative specimens. Xpert MTB/RIF also correctly excluded 99.2% (121/122) of nontuberculous mycobacteria (NTM) specimens, including all 33 NTM false-positives by smear microscopy. For the detection of RIF resistance, Xpert MTB/RIF sensitivity and specificity were 100% and 98.3%, respectively. Our findings demonstrate that Xpert MTB/RIF is able to accurately detect MTBC and RIF resistance in routinely collected respiratory specimens in a low TB-incidence setting, with comparable performance to that achieved in high-incidence settings; and suggest that under these conditions the assay has particular utility in detecting smear-negative TB cases, excluding smear-positive patients without MTBC disease, and differentiating MTBC from NTM. PMID:29016684

Large-Scale Weibull Analysis of H-451 Nuclear- Grade Graphite Specimen Rupture Data

NASA Technical Reports Server (NTRS)

Nemeth, Noel N.; Walker, Andrew; Baker, Eric H.; Murthy, Pappu L.; Bratton, Robert L.

2012-01-01

A Weibull analysis was performed of the strength distribution and size effects for 2000 specimens of H-451 nuclear-grade graphite. The data, generated elsewhere, measured the tensile and four-point-flexure room-temperature rupture strength of specimens excised from a single extruded graphite log. Strength variation was compared with specimen location, size, and orientation relative to the parent body. In our study, data were progressively and extensively pooled into larger data sets to discriminate overall trends from local variations and to investigate the strength distribution. The CARES/Life and WeibPar codes were used to investigate issues regarding the size effect, Weibull parameter consistency, and nonlinear stress-strain response. Overall, the Weibull distribution described the behavior of the pooled data very well. However, the issue regarding the smaller-than-expected size effect remained. This exercise illustrated that a conservative approach using a two-parameter Weibull distribution is best for designing graphite components with low probability of failure for the in-core structures in the proposed Generation IV (Gen IV) high-temperature gas-cooled nuclear reactors. This exercise also demonstrated the continuing need to better understand the mechanisms driving stochastic strength response. Extensive appendixes are provided with this report to show all aspects of the rupture data and analytical results.

Development of a specimen heating holder with an evaporator and gas injector and its application for catalyst.

PubMed

Takeo, Kamino; Toshie, Yaguchi; Mitsuru, Konno; Akira, Watabe; Yasuhira, Nagakubo

2006-10-01

A specimen heating holder equipped with a gas injector and an evaporator has been developed for use with conventional transmission electron microscopes (TEMs). The developed specimen holder allows both synthesis of metal oxide support and deposition of catalyst nano-particles in situ. Since the holder is designed to be used in small gapped high-resolution objective lens pole-piece, all the procedure from the synthesis of support material to the deposition of catalyst as well as the behavior of the catalyst nano-particles on the support can be observed at near atomic resolution. The developed specimen holder was applied to the study of AuPd catalyst. First, air was injected onto heated aluminum particles via a gas injector to synthesize Al(2)O(3) support. Then, nano-particles of AuPd were deposited on the Al(2)O(3) support. After the deposition, the synthesized Al(2)O(3) support was heated and air was injected again to observe behaviors of the deposited AuPd nano-particles at elevated temperatures in the aerial environment. Behaviors of the AuPd nano-particles such as coalescence, segmentation and diffusion to the Al(2)O(3) support were dynamically observed at atomic level high resolution.

Fabrication and testing of SMA composite beam with shape control

NASA Astrophysics Data System (ADS)

Noolvi, Basavaraj; S, Raja; Nagaraj, Shanmukha; Mudradi, Varada Raj

2017-07-01

Smart materials are the advanced materials that have characteristics of sensing and actuation in response to the external stimuli like pressure, heat or electric charge etc. These materials can be integrated in to any structure to make it smart. From the different types of smart materials available, Shape Memory Alloy (SMA) is found to be more useful in designing new applications, which can offer more actuating speed, reduce the overall weight of the structure. The unique property of SMA is the ability to remember and recover from large strains of upto 8% without permanent deformation. Embedding the SMA wire/sheet in fiber-epoxy/flexible resin systems has many potential applications in Aerospace, Automobile, Medical, Robotics and various other fields. In this work the design, fabrication, and testing of smart SMA composite beam has been carried out. Two types of epoxy based resin systems namely LY 5210 resin system and EPOLAM 2063 resin system are used in fabricating the SMA composite specimens. An appropriate mould is designed and fabricated to retain the pre-strain of SMA wire during high temperature post curing of composite specimens. The specimens are fabricated using vacuum bag technique.

A New Experimental Design for Bacterial Microleakage Investigation at the Implant-Abutment Interface: An In Vitro Study.

PubMed

Zipprich, Holger; Miatke, Sven; Hmaidouch, Rim; Lauer, Hans-Christoph

2016-01-01

This study aimed to test bacterial microleakage at the implant-abutment interface (IAI) before and after dynamic loading using a new chewing simulation. Fourteen implant systems (n = 5 samples of each) were divided into two groups: (1) systems with conical implant-abutment connections (IACs), and (2) systems with flat IACs. For collecting samples without abutment disconnection, channels (Ø = 0.3 mm) were drilled into implants perpendicularly to their axes, and stainless-steel cannulas were adhesively glued inside these channels to allow a sterilized rinsing solution to enter the implant interior and to exit with potential contaminants for testing. Implants were embedded in epoxy resin matrices, which were supported by titanium cylinders with lateral openings for inward and outward cannulas. Abutments were tightened and then provided with vertically adjustable, threaded titanium balls, which were cemented using composite cement. Specimens were immersed in a bacterial liquid and after a contact time of 15 minutes, the implant interior was rinsed prior to chewing simulation (0 N ≘ static seal testing). Specimens were exposed to a Frankfurt chewing simulator. Two hundred twenty force cycles per power level (110 in ± X-axis) were applied to simulate a daily masticatory load of 660 chewing cycles (equivalent to 1,200,000 cycles/5 years). The applied load was gradually increased from 0 N to a maximum load of 200 N in 25-N increments. The implant interior was rinsed to obtain samples before each new power level. All samples were tested using fluorescence microscopy; invading microorganisms could be counted and evaluated. No bacterial contamination was detected under static loading conditions in both groups. After loading, bacterial contamination was detected in one sample from one specimen in group 1 and in two samples from two specimens in group 2. Controlled dynamic loading applied in this study simulated a clinical situation and enabled time-dependent analysis regarding the bacterial seal of different implant systems. Conical IACs offer a better bacterial seal compared with flat IACs, which showed increased microleakage after dynamic loading. IAC design plays a crucial role in terms of bacterial colonization. Taking samples of the implant interior without abutment disconnection eliminates an error source.

FY 2017-Progress Report on the Design and Construction of the Sodium Loop SMT-3

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

Natesan, K.; Momozaki, Y.

This report provides an update on the design of a forced-convection sodium loop to be used for the evaluation of sodium compatibility of advanced Alloy 709 with emphasis on long term exposures of tensile, creep, fatigue, creep fatigue, and fracture toughness ASTM-size specimens in support of ASME Code qualification and NRC licensing. The report is a deliverable (Level 4) in FY17 (M4AT-17AN1602094), under the Work Package AT-17AN160209, “Sodium Compatibility” performed by Argonne National Laboratory (ANL), as part of the Advanced Materials Program for the Advanced Reactor Technology. This work package enables the development of advanced structural materials by providing corrosion,more » microstructure, and mechanical property data from the standpoint of sodium compatibility of advanced structural alloys. The first sodium loop (SMT-1) with a single tank was constructed in 2011 at ANL and has been in operation for exposure of subsize sheet specimens of advanced alloys at a single temperature. The second sodium loop with dual tanks (SMT-2) was constructed in 2013 and has been in operation for the exposure of subsize sheet specimens of advanced alloys at two different temperatures. The current loop (SMT-3) has been designed to incorporate sufficient chamber capacity to expose a large number of ASTM-size specimens to evaluate the sodium effects on tensile, creep, fatigue, creep-fatigue, and fracture toughness properties, in support of ASME Code Qualification and USNRC Licensing. The design of individual components for the third sodium loop SMT-3 is almost complete. The design also has been sent to an outside vendor for piping analysis to be in compliance with ASME Code. A purchase order has been placed with an outside vendor for the fabrication of major components such as the specimen exposure tanks. However, we have contracted with another vendor to establish the piping design in compliance with ASME design codes. The piping design was completed in FY2017 and the information is being transmitted to the tank fabricator. The SMT-3 loop will be located in Building 206 adjacent to the currently operating SMT-2 loop. In addition, we have demolished the aged power supply system in Building 206 and installed a new transformer, wiring, and power panels for the new loop. Procurement of some of the long lead items such as valves, EM pumps, EM flowmeters, etc. is in progress and will continue in FY 2018. The construction of components such as cold trap, economizers, piping arrangement etc. will be performed in the central shops at ANL. About 150 liters of sodium for the loop will be procured in early FY2018. The loop system is designed to circulate sodium through the sample tanks and the associated loop without an operator for an extended period of time. With the three sodium loops (with single-tank, dual-tank and four–tanks), materials can be tested at different sodium temperatures, and large tensile, creep, fatigue, creep-fatigue, and fracture toughness specimens can be exposed to sodium for extended periods of time and generate data on mechanical properties in support of ASME Code Qualification and USNRC Licensing of advanced Alloy 709 for use as a structural material in SFRs.« less

Adaptive scapula bone remodeling computational simulation: Relevance to regenerative medicine

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

Sharma, Gulshan B., E-mail: gbsharma@ucalgary.ca; University of Pittsburgh, Swanson School of Engineering, Department of Bioengineering, Pittsburgh, Pennsylvania 15213; University of Calgary, Schulich School of Engineering, Department of Mechanical and Manufacturing Engineering, Calgary, Alberta T2N 1N4

Shoulder arthroplasty success has been attributed to many factors including, bone quality, soft tissue balancing, surgeon experience, and implant design. Improved long-term success is primarily limited by glenoid implant loosening. Prosthesis design examines materials and shape and determines whether the design should withstand a lifetime of use. Finite element (FE) analyses have been extensively used to study stresses and strains produced in implants and bone. However, these static analyses only measure a moment in time and not the adaptive response to the altered environment produced by the therapeutic intervention. Computational analyses that integrate remodeling rules predict how bone will respondmore » over time. Recent work has shown that subject-specific two- and three dimensional adaptive bone remodeling models are feasible and valid. Feasibility and validation were achieved computationally, simulating bone remodeling using an intact human scapula, initially resetting the scapular bone material properties to be uniform, numerically simulating sequential loading, and comparing the bone remodeling simulation results to the actual scapula’s material properties. Three-dimensional scapula FE bone model was created using volumetric computed tomography images. Muscle and joint load and boundary conditions were applied based on values reported in the literature. Internal bone remodeling was based on element strain-energy density. Initially, all bone elements were assigned a homogeneous density. All loads were applied for 10 iterations. After every iteration, each bone element’s remodeling stimulus was compared to its corresponding reference stimulus and its material properties modified. The simulation achieved convergence. At the end of the simulation the predicted and actual specimen bone apparent density were plotted and compared. Location of high and low predicted bone density was comparable to the actual specimen. High predicted bone density was greater than actual specimen. Low predicted bone density was lower than actual specimen. Differences were probably due to applied muscle and joint reaction loads, boundary conditions, and values of constants used. Work is underway to study this. Nonetheless, the results demonstrate three dimensional bone remodeling simulation validity and potential. Such adaptive predictions take physiological bone remodeling simulations one step closer to reality. Computational analyses are needed that integrate biological remodeling rules and predict how bone will respond over time. We expect the combination of computational static stress analyses together with adaptive bone remodeling simulations to become effective tools for regenerative medicine research.« less

Adaptive scapula bone remodeling computational simulation: Relevance to regenerative medicine

NASA Astrophysics Data System (ADS)

Sharma, Gulshan B.; Robertson, Douglas D.

2013-07-01

Shoulder arthroplasty success has been attributed to many factors including, bone quality, soft tissue balancing, surgeon experience, and implant design. Improved long-term success is primarily limited by glenoid implant loosening. Prosthesis design examines materials and shape and determines whether the design should withstand a lifetime of use. Finite element (FE) analyses have been extensively used to study stresses and strains produced in implants and bone. However, these static analyses only measure a moment in time and not the adaptive response to the altered environment produced by the therapeutic intervention. Computational analyses that integrate remodeling rules predict how bone will respond over time. Recent work has shown that subject-specific two- and three dimensional adaptive bone remodeling models are feasible and valid. Feasibility and validation were achieved computationally, simulating bone remodeling using an intact human scapula, initially resetting the scapular bone material properties to be uniform, numerically simulating sequential loading, and comparing the bone remodeling simulation results to the actual scapula's material properties. Three-dimensional scapula FE bone model was created using volumetric computed tomography images. Muscle and joint load and boundary conditions were applied based on values reported in the literature. Internal bone remodeling was based on element strain-energy density. Initially, all bone elements were assigned a homogeneous density. All loads were applied for 10 iterations. After every iteration, each bone element's remodeling stimulus was compared to its corresponding reference stimulus and its material properties modified. The simulation achieved convergence. At the end of the simulation the predicted and actual specimen bone apparent density were plotted and compared. Location of high and low predicted bone density was comparable to the actual specimen. High predicted bone density was greater than actual specimen. Low predicted bone density was lower than actual specimen. Differences were probably due to applied muscle and joint reaction loads, boundary conditions, and values of constants used. Work is underway to study this. Nonetheless, the results demonstrate three dimensional bone remodeling simulation validity and potential. Such adaptive predictions take physiological bone remodeling simulations one step closer to reality. Computational analyses are needed that integrate biological remodeling rules and predict how bone will respond over time. We expect the combination of computational static stress analyses together with adaptive bone remodeling simulations to become effective tools for regenerative medicine research.

Composite shade guides and color matching.

PubMed

Paolone, Gaetano; Orsini, Giovanna; Manauta, Jordi; Devoto, Walter; Putignano, Angelo

2014-01-01

Finding reliable systems that can help the clinician match the color of direct composite restorations is often an issue. After reviewing several composite shade guides available on the market and outlining their main characteristics and limits (unrealistic specimen thickness, not made with the same material the clinician will use, only a few allow to overlap enamel tabs on dentin ones), the authors evaluated the reliability of a system designed to produce self-made standardized "tooth-shaped" shade guide specimens. Small changes in composite enamel thickness may determine huge differences in esthetic outcomes. In conclusion, the results showed that all the specimens demonstrated comparable enamel thickness in all the examined areas (cervical, middle, incisal).

Changes in hospitality workers' exposure to secondhand smoke following the implementation of New York's smoke-free law

PubMed Central

Farrelly, M; Nonnemaker, J; Chou, R; Hyland, A; Peterson, K; Bauer, U

2005-01-01

Objective: To assess the impact on hospitality workers' exposure to secondhand smoke of New York's smoke-free law that prohibits smoking in all places of employment, including restaurants, bars, and bowling facilities. Design: Pre-post longitudinal follow up design. Settings: Restaurants, bars, and bowling facilities in New York State. Subjects: At baseline, 104 non-smoking workers in restaurants, bars, and bowling facilities were recruited with newspaper ads, flyers, and radio announcements. Of these, 68 completed a telephone survey and provided at least one saliva cotinine specimen at baseline. At three, six, and 12 month follow up studies, 47, 38, and 32 workers from the baseline sample of 68 completed a telephone survey and provided at least one saliva cotinine specimen. Intervention: The smoke-free law went into effect 24 July 2003. Main outcome measures: Self reported sensory and respiratory symptoms and exposure to secondhand smoke; self administered saliva cotinine specimens. Analyses were limited to subjects in all four study periods who completed a telephone survey and provided at least one saliva cotinine specimen. Results: All analyses were limited to participants who completed both an interview and a saliva specimen for all waves of data collection (n = 30) and who had cotinine concentrations ⩽ 15 ng/ml (n = 24). Hours of exposure to secondhand smoke in hospitality jobs decreased from 12.1 hours (95% confidence interval (CI) 8.0 to 16.3 hours) to 0.2 hours (95% CI –0.1 to 0.5 hours) (p < 0.01) and saliva cotinine concentration decreased from 3.6 ng/ml (95% CI 2.6 to 4.7 ng/ml) to 0.8 ng/ml (95% CI 0.4 to 1.2 ng/ml) (p < 0.01) from baseline to the 12 month follow up. The prevalence of workers reporting sensory symptoms declined from 88% (95% CI 66% to 96%) to 38% (95% CI 20% to 59%) (p < 0.01); there was no change in the overall prevalence of upper respiratory symptoms (p < 0.16). Conclusion: New York's smoke-free law had its intended effect of protecting hospitality workers from exposure to secondhand smoke within three months of implementation. One year after implementation, the results suggest continued compliance with the law. PMID:16046685

Evaluation of a Reformulated CHROMagar Candida

PubMed Central

Jabra-Rizk, Mary Ann; Brenner, Troy M.; Romagnoli, Mark; Baqui, A. A. M. A.; Merz, William G.; Falkler, William A.; Meiller, Timothy F.

2001-01-01

CHROMagar Candida is a differential culture medium for the isolation and presumptive identification of clinically important yeasts. Recently the medium was reformulated by Becton Dickinson. This study was designed to evaluate the performance of the new formula of CHROMagar against the original CHROMagar Candida for recovery, growth, and colony color with stock cultures and with direct plating of clinical specimens. A total of 90 stock yeast isolates representing nine yeast species, including Candida dubliniensis, as well as 522 clinical specimens were included in this study. No major differences were noted in growth rate or colony size between the two media for most of the species. However, all 10 Candida albicans isolates evaluated consistently gave a lighter shade of green on the new CHROMagar formulation. In contrast, all 26 C. dubliniensis isolates gave the same typical dark green color on both media. A total of 173 of the 522 clinical specimens were positive for yeast, with eight yeast species recovered. The recovery rates for each species were equivalent on both media, with no consistent species-associated differences in colony size or color. Although both media were comparable in performance, the lighter green colonies of C. albicans isolates on the new CHROMagar made it easier to differentiate between C. albicans and C. dubliniensis isolates. In conclusion, the newly formulated Becton Dickinson CHROMagar Candida medium is as equally suited as a differential medium for the presumptive identification of yeast species and for the detection of multiple yeast species in clinical specimens as the original CHROMagar Candida medium. PMID:11326038

Measurement of elasto-plastic deformations by speckle interferometry

NASA Astrophysics Data System (ADS)

Bova, Marco; Bruno, Luigi; Poggialini, Andrea

2010-09-01

In the paper the authors present an experimental equipment for elasto-plastic characterization of engineering materials by tensile tests. The stress state is imposed to a dog bone shaped specimen by a testing machine fixed on the optical table and designed for optimizing the performance of a speckle interferometer. All three displacement components are measured by a portable speckle interferometer fed by three laser diodes of 50 mW, by which the deformations of a surface of about 6×8 mm2 can be fully analyzed in details. All the equipment is driven by control electronics designed and realized on purpose, by which it is possible to accurately modify the intensity of the illumination sources, the position of a PZT actuator necessary for applying phase-shifting procedure, and the overall displacement applied to the specimen. The experiments were carried out in National Instrument LabVIEW environment, while the processing of the experimental data in Wolfram Mathematica environment. The paper reports the results of the elasto-plastic characterization of a high strength steel specimen.

Low Activation Joining of SiC/SiC Composites for Fusion Applications: Modeling Miniature Torsion Tests with Elastic and Elastic-Plastic Models

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

Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

2015-03-01

The use of SiC and SiC-composites in fission or fusion environments requires joining methods for assembling systems. The international fusion community designed miniature torsion specimens for joint testing and irradiation in test reactors with limited irradiation volumes. These torsion specimens fail out-of-plane when joints are strong and when elastic moduli are within a certain range compared to SiC, which causes difficulties in determining shear strengths for joints or for comparing unirradiated and irradiated joints. A finite element damage model was developed that indicates fracture is likely to occur within the joined pieces to cause out-of-plane failures for miniature torsion specimensmore » when a certain modulus and strength ratio between the joint material and the joined material exists. The model was extended to treat elastic-plastic joints such as SiC/epoxy and steel/epoxy joints tested as validation of the specimen design.« less

An Electromagnetic Tool for Damping and Fatigue Analysis

DTIC Science & Technology

2004-03-01

Serway , Raymond A . Physics For Scientists & Engineers (3rd Edition). Philadelphia: Saunders College Publishing, 1990. 15. Kurtus, Ron...system was initially designed to reduce the time and manpower required to characterize damping treatments. It is based on a digitally controlled...the capability to study fatigue under a free boundary condition. The system consists of a test specimen suspended by a pendulum to closely

Microgravity

NASA Image and Video Library

1998-10-10

Breast tissue specimens in traditional sample dishes. NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cells (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunourous tissues.

Censoring Data for Resistance Factor Calculations in Load and Resistance Factor Design: A Preliminary Study

Treesearch

James W. Evans; David W. Green

2007-01-01

Reliability estimates for the resistance distribution of wood product properties may be made from test data where all specimens are broken (full data sets) or by using data sets where information is obtained only from the weaker pieces in the distribution (censored data). Whereas considerable information exists on property estimation from full data sets, much less...

A selective medium for the isolation of Microbacterium species in oral cavities.

PubMed

Tsuzukibashi, Osamu; Uchibori, Satoshi; Kobayashi, Taira; Saito, Masanori; Umezawa, Koji; Ohta, Mitsuhiro; Shinozaki-Kuwahara, Noriko

2015-09-01

The genus Microbacterium has been isolated from the environment, dairy goods, and human clinical specimens. Although, in our previous studies, some Microbacterium species were infrequently detected in oral samples collected from humans, there is currently no report that these organisms, which are capable of causing serious systemic infections, were isolated from the human oral cavity. The aim of the present study was to develop a selective medium to isolate the representative Microbacterium species most frequently detected in human clinical specimens, and reveal the distribution of individual Microbacterium species in the oral cavity. The growth recoveries of representative Microbacterium species on the selective medium, designated as MSM, were sufficient. Moreover, the growth of other representative oral bacteria was markedly inhibited on the selective medium. The proportion of Microbacterium species in the saliva samples of 60 subjects, 20 of whom were removable denture wearers, was then examined. The proportion of these organisms was also examined in environmental samples obtained by swabbing 20 washstands. PCR primers were designed for representative Microbacterium species. The genus Microbacterium was detected in 45% of the saliva and denture plaque samples collected from the twenty removable denture wearers, but was absent in the saliva of the forty non-denture wearers. On the other hand, these organisms were detected in all environmental samples. The genus Microbacterium accounted for 0.00003%, 0.0001%, and 12.6% of the total cultivable bacteria number on the BHI medium in the saliva and denture plaque samples of removable denture wearers and in the environmental samples, respectively. The most predominant Microbacterium species in all positive samples was Microbacterium oxydans. These results indicated that the genus Microbacterium was not a part of the normal flora in the human oral cavity, except for subjects wearing dentures that were contaminated by the environment, and the selective medium, designated as MSM, was useful for isolating Microbacterium species, which are frequently encountered in human clinical specimens, from the various samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Cytochrome c oxidase I primers for corbiculate bees: DNA barcode and mini-barcode.

PubMed

Françoso, E; Arias, M C

2013-09-01

Bees (Apidae), of which there are more than 19 900 species, are extremely important for ecosystem services and economic purposes, so taxon identity is a major concern. The goal of this study was to optimize the DNA barcode technique based on the Cytochrome c oxidase (COI) mitochondrial gene region. This approach has previously been shown to be useful in resolving taxonomic inconsistencies and for species identification when morphological data are poor. Specifically, we designed and tested new primers and standardized PCR conditions to amplify the barcode region for bees, focusing on the corbiculate Apids. In addition, primers were designed to amplify small COI amplicons and tested with pinned specimens. Short barcode sequences were easily obtained for some Bombus century-old museum specimens and shown to be useful as mini-barcodes. The new primers and PCR conditions established in this study proved to be successful for the amplification of the barcode region for all species tested, regardless of the conditions of tissue preservation. We saw no evidence of Wolbachia or numts amplification by these primers, and so we suggest that these new primers are of broad value for corbiculate bee identification through DNA barcode. © 2013 John Wiley & Sons Ltd.

Effects of heat treatments and UV exposures on mechanical properties of 3D printed acrylonitrile butadiene styrene specimens

NASA Astrophysics Data System (ADS)

Hughes, Shawn M.; Alamir, Mohammed; Neas, Brian; Alzahrani, Naif; Asmatulu, Ramazan

2017-04-01

Over the last few years, tremendous amount of research efforts has been conducted on 3D printing materials, methods and systems. Various 3D printer materials in different size, shape and geometry can be used for advanced designs, modeling, and manufacturing for different industrial applications. In the present study, dog bone shape specimen was designed via a CATIA CAD model, and then printed by a 3D printer using a polymeric filament (acrylonitrile butadiene styrene - ABS). Some of the prepared samples were heat treated at 40 °C, 60 °C, and 80 °C for 30 minutes, while the others were exposed to the UV light in a chamber for 0, 5, 10, 15 and 20 days. The surface and mechanical properties of the conditioned samples were determined using water contact angle and tensile test units, respectively. The test results indicated that the heat treatment process increased the mechanical properties; however, the UV exposure tests significantly reduced the water contact angle and properties of the samples. During these studies, undergraduate engineering students were involved in the tests, and gained a lot of hands-on research experiences.

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...

Control of brushing variables for the in vitro assessment of toothpaste abrasivity using a novel laboratory model.

PubMed

Parry, Jason; Harrington, Edward; Rees, Gareth D; McNab, Rod; Smith, Anthony J

2008-02-01

Design and construct a tooth-brushing simulator incorporating control of brushing variables including brushing force, speed and temperature, thereby facilitating greater understanding of their importance in toothpaste abrasion testing methodologies. A thermostable orbital shaker was selected as a base unit and 16- and 24-specimen brushing rigs were constructed to fit inside, consisting of: a square bath partitioned horizontally to provide brushing channels, specimen holders for 25 mm diameter mounted specimens to fit the brushing channels and individually weighted brushing arms, able to support four toothbrush holders suspended over the brushing channels. Brush head holders consisted of individually weighted blocks of Delrin, or PTFE onto which toothbrush heads were fixed. Investigating effects of key design criteria involved measuring abrasion depths of polished human enamel and dentine. The brushing simulator demonstrated good reproducibility of abrasion on enamel and dentine across consecutive brushing procedures. Varying brushing parameters had a significant impact on wear results: increased brushing force demonstrated a trend towards increased wear, with increased reproducibility for greater abrasion levels, highlighting the importance of achieving sufficient wear to optimise accuracy; increasing brushing temperature demonstrated increased enamel abrasion for silica and calcium carbonate systems, which may be related to slurry viscosities and particle suspension; varying brushing speed showed a small effect on abrasion of enamel at lower brushing speed, which may indicate the importance of maintenance of the abrasive in suspension. Adjusting key brushing variables significantly affected wear behaviour. The brushing simulator design provides a valuable model system for in vitro assessment of toothpaste abrasivity and the influence of variables in a controlled manner. Control of these variables will allow more reproducible study of in vitro tooth wear processes.

46 CFR 154.610 - Design temperature not colder than 0 °C (32 °F).

Code of Federal Regulations, 2011 CFR

2011-10-01

... Charpy V-notch impact energy must be determined for: (1) Each plate as rolled; and (2) Each five short... orientation and required impact energy of a 10 mm × 10 mm (0.394 in. × 0.394 in.) Charpy V-notch specimen must... temperature of the Charpy V-notch specimens is as follows: Material Thickness Test Temperature t≤20 mm (0.788...

Advantages of Residual Stresses in Dynamically Riveted Joints.

DTIC Science & Technology

1978-02-01

strain distribution around a rivet hole, and describes an experimental method for measuring the radial velocity of an expanding rivet. The advantages of... benefits of compressive residual stresses in riveted joints, fatigue specimens made of 2024-T81 aluminum were used. The specimens were tested at constant...concentration of in-service tensile stresses near the hole surfaze. Substan;Aal and significant benefits in design life and structural weight can be

The accomplishments of lithium target and test facility validation activities in the IFMIF/EVEDA phase

NASA Astrophysics Data System (ADS)

Arbeiter, Frederik; Baluc, Nadine; Favuzza, Paolo; Gröschel, Friedrich; Heidinger, Roland; Ibarra, Angel; Knaster, Juan; Kanemura, Takuji; Kondo, Hiroo; Massaut, Vincent; Saverio Nitti, Francesco; Miccichè, Gioacchino; O'hira, Shigeru; Rapisarda, David; Sugimoto, Masayoshi; Wakai, Eiichi; Yokomine, Takehiko

2018-01-01

As part of the engineering validation and engineering design activities (EVEDA) phase for the international fusion materials irradiation facility IFMIF, major elements of a lithium target facility and the test facility were designed, prototyped and validated. For the lithium target facility, the EVEDA lithium test loop was built at JAEA and used to test the stability (waves and long term) of the lithium flow in the target, work out the startup procedures, and test lithium purification and analysis. It was confirmed by experiments in the Lifus 6 plant at ENEA that lithium corrosion on ferritic martensitic steels is acceptably low. Furthermore, complex remote handling procedures for the remote maintenance of the target in the test cell environment were successfully practiced. For the test facility, two variants of a high flux test module were prototyped and tested in helium loops, demonstrating their good capabilities of maintaining the material specimens at the desired temperature with a low temperature spread. Irradiation tests were performed for heated specimen capsules and irradiation instrumentation in the BR2 reactor at SCK-CEN. The small specimen test technique, essential for obtaining material test results with limited irradiation volume, was advanced by evaluating specimen shape and test technique influences.

Design and evaluation of a foam-filled hat-stiffened panel concept for aircraft primary structural applications

NASA Technical Reports Server (NTRS)

Ambur, Damodar R.

1993-01-01

Geodesically stiffened structures are very efficient in carrying combined bending, torsion, and pressure loading that is typical of primary aircraft structures. They are also very damage tolerant since there are multiple load paths available to redistribute loads compared to prismatically stiffened structures. Geodesically stiffened structures utilize continuous filament composite materials which make them amenable to automated manufacturing processes to reduce cost. The current practice for geodesically stiffened structures is to use a solid blade construction for the stiffener. This stiffener configuration is not an efficient concept and there is a need to identify other stiffener configurations that are more efficient but utilize the same manufacturing process as the solid blade. This paper describes a foam-filled stiffener cross section that is more efficient than a solid-blade stiffener in the load range corresponding to primary aircraft structures. A prismatic hat-stiffener panel design is then selected for structural evaluation in uni-axial compression with and without impact damage. Experimental results for both single stiffener specimens and multi-stiffener panel specimens are presented. Finite element analysis results are presented that predict the buckling and postbuckling response of the test specimens. Analytical results for both the element and panel specimens are compared with experimental results.

In situ monitored in-pile creep testing of zirconium alloys

NASA Astrophysics Data System (ADS)

Kozar, R. W.; Jaworski, A. W.; Webb, T. W.; Smith, R. W.

2014-01-01

The experiments described herein were designed to investigate the detailed irradiation creep behavior of zirconium based alloys in the HALDEN Reactor spectrum. The HALDEN Test Reactor has the unique capability to control both applied stress and temperature independently and externally for each specimen while the specimen is in-reactor and under fast neutron flux. The ability to monitor in situ the creep rates following a stress and temperature change made possible the characterization of creep behavior over a wide stress-strain-rate-temperature design space for two model experimental heats, Zircaloy-2 and Zircaloy-2 + 1 wt%Nb, with only 12 test specimens in a 100-day in-pile creep test program. Zircaloy-2 specimens with and without 1 wt% Nb additions were tested at irradiation temperatures of 561 K and 616 K and stresses ranging from 69 MPa to 455 MPa. Various steady state creep models were evaluated against the experimental results. The irradiation creep model proposed by Nichols that separates creep behavior into low, intermediate, and high stress regimes was the best model for predicting steady-state creep rates. Dislocation-based primary creep, rather than diffusion-based transient irradiation creep, was identified as the mechanism controlling deformation during the transitional period of evolving creep rate following a step change to different test conditions.

A Tensile Specimen of Tailor Rolled Blanks with Equal Probability in Yield and Its Mechanical Behavior Analysis

PubMed Central

Zhang, Sijia; Liu, Xianghua; Liu, Lizhong

2018-01-01

In this paper, the microstructure and mechanical properties that distribute regulation along the rolling direction of tailor rolled blanks (TRB) were investigated. A tensile specimen with equal probability in yield (EYS) was first designed considering variation both in thickness and in material strength. The uniaxial tension test was carried out with a digital image correlation method to analyze the mechanical behaviors. The results showed that the strain distribution of EYS was homogeneous. From the results, it can be known that a new design philosophy for a TRB tensile specimen is reasonable and EYS is suitable to characterize the mechanical behavior of TRB. The true stress-strain curves of metal in different cross sections of TRB were calculated. On the basis of the true stress-strain curves, a material model of TRB was constructed and then implemented into finite element simulations of TRB uniaxial tensile tests. The strain distribution of numerical and experimental results was similar and the error between the elongation of the specimen after fracture obtained by experiment and FE ranged from 9.51% to 13.06%. Therefore, the simulation results match well with the experimental results and the material model has high accuracy and as well as practicability. PMID:29710772

Experimental evaluation of outer planets probe thermal insulation concepts

NASA Technical Reports Server (NTRS)

Grote, M. G.; Mezines, S. A.

1976-01-01

An experimental program was conducted to evaluate various thermal insulation concepts for use in the Outer Planets Probe (OPP) during entry and descent into the atmospheres of Jupiter, Saturn, and Uranus. Phenolic fiberglass honeycomb specimens representative of the OPP structure were packed and tested with various fillers: Thermal conductivity measurements were made over a temperature range of 300 K to 483 K and pressures from vacuum up to 10 atmospheres in helium and nitrogen gas environments. The conductivity results could not be fully explained so new test specimens were designed with improved venting characteristics, and tested to determine the validity of the original data. All of the conductivity data showed results that were substantially higher than expected. The original test data in helium were lower than the data from the redesigned specimens, probably due to inadequate venting of nitrogen gas from the original specimens. The thermal conductivity test results show only a marginal improvement in probe thermal protection performance for a filled honeycomb core compared to an unfilled core. In addition, flatwise tension tests showed a severe bond strength degradation due to the inclusion of either the powder or foam fillers. In view of these results, it is recommended that the baseline OPP design utilize an unfilled core.

Water sensitivity of the seismic properties of polycrystalline olivine

NASA Astrophysics Data System (ADS)

Cline, C. J., II; Jackson, I.; Faul, U.; Berry, A.

2016-12-01

Fully synthetic solgel-derived Fo90 olivine specimens have been fabricated with varying concentrations of hydroxyl, chemically bound as doubly protonated Si vacancies associated with nearby Ti/Mg substitution (the `Ti-clinohumite' defect). The `water' contents of three such specimens hot-pressed within welded Pt capsules are controlled by the amount of added TiO2-dopant and ranged between 176 and 802 ppm Ti/Si, providing concentrations of bound hydrogen ranging between 330 and 1150 ppm H/Si respectively. These sol-gel derived specimens, along with another natural Ti-bearing specimen hot-pressed from powder produced by grinding hand-picked single crystals of San Carlos olivine, were then each subsequently wrapped in Pt and interrogated under water-undersaturated conditions via forced torsional oscillation. Testing was conducted at seismic periods of 1 - 1000 s and 200 MPa confining pressure during slow staged cooling from 1200 to 25 °C. All Ti-doped hydrous specimens tested, including the San Carlos olivine specimen, show high temperature background behavior, involving monotonically increasing levels of dissipation and decreasing values of shear modulus with increasing oscillation period and increasing temperature. Comparison of the mechanical behavior observed in these water-undersaturated specimens to that for a similarly fabricated dry Ti-bearing olivine specimen shows a striking contrast, with much more dissipation and lower modulus observed in the hydrous specimens, but with limited sensitivity of seismic properties to the total water content among the hydrous specimens in the series. Further experiments in progress on Pt-sleeved, dry, undoped Fo90 are designed to clarify further the sensitivity of the seismic properties to water content and possibly oxygen fugacity.

Biomechanical evaluation of potential damage to hernia repair materials due to fixation with helical titanium tacks.

PubMed

Lerdsirisopon, Sopon; Frisella, Margaret M; Matthews, Brent D; Deeken, Corey R

2011-12-01

This study aimed to determine whether the strength and extensibility of hernia repair materials are negatively influenced by the application of helical titanium tacks. This study evaluated 14 meshes including bare polypropylene, macroporous polytetrafluoroethylene, absorbable barrier, partially absorbable mesh, and expanded polytetrafluoroethylene materials. Each mesh provided 15 specimens, which were prepared in 7.5 × 7.5-cm squares. Of these, 5 "undamaged" specimens were subjected to ball-burst testing to determine their biomechanical properties before application of helical titanium tacks (ProTack). To 10 "damaged" specimens 7 tacks were applied 1 cm apart in a 3.5-cm-diameter circle using a tacking force of 25 to 28 N. The tacks were removed from five of the specimens before ball-burst testing and left intact in the remaining five specimens. The application of tacks had no effect on the tensile strength of Dualmesh, ProLite Ultra, Infinit, Ultrapro, C-QUR Lite (<6 in.), Prolene Soft, or Physiomesh, but the tensile strengths were reduced for Bard Mesh, C-QUR, ProLite, and C-QUR Lite (>6 in.). Most of the meshes did not exhibit significantly different tensile strengths between removal of tacks and tacks left intact. Exceptions included C-QUR, Prolene, Ultrapro, and Bard Soft Mesh, which were weaker with removal of tacks than with tacks left intact during the test. Damage due to the application of helical titanium tacks also caused increased strain at a stress of 16 N/cm for all the meshes except C-QUR Lite (>6 in.) and Physiomesh. Many of the meshes evaluated in this study exhibited damage in the form of reduced tensile strength and increased extensibility after the application of tacks compared with the corresponding "undamaged" meshes. Meshes with smaller interstices and larger filaments were influenced negatively by the application of helical titanium tacks, whereas mesh designs with larger interstices and smaller filaments tended to maintain their baseline mechanical properties.

Results of the "Komplast" experiment on the long-term exposure of materials specimens on the ISS surface

NASA Astrophysics Data System (ADS)

Shumov, Andrey; Novikov, Lev

The "Komplast" materials experiment was designed by the Khrunichev State Research and Production Space Center together with Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University and other Russian scientific institutes, and has been carried out since 1998. The aim of the experiment is to study the complex effects of space factors on specimens of various materials. Eight “Komplast” panels fitted with material specimens equipped UV-sensors and temperature sensors were located on the International Space Station (ISS) Functional Cargo Block (FGB) module exterior surface. The panels were sent into orbit with the FGB when it launched on November 20, 1998. Two of these panels were subsequently returned to Earth by Space Shuttle Discovery after 12 years of LEO exposure. The uniqueness of the "Komplast" experiment determined by long duration of open space exposure, which is much longer than in other similar experiments. For example LDEF: 1984-1990, HEEI (Space Station "Mir"): 1996-1997, MISSE-1, -2 (ISS): 1,5-2 years. In this work reveals laboratory research results of some materials specimens, which had been exposed on “Komplast” panels. A distinctive feature of this research was additional irradiation of specimens by atomic oxygen and electrons with energies of ~ 1-8 MeV in laboratory. In the interpretation of the experiment results was taken into account the specimens exposure temperature conditions on the ISS exterior surface and the conditions of their sunlit, defined by the above-mentioned sensors readings. Lot of attention was paid to the investigation of rubber materials specimens. The deformation, mechanical and relaxation characteristics were defined for the specimens. Also were investigations the seals-ability of model rubber seals after the long-term outer exposure. It was determined conservation volumetric deformation and relaxation characteristics of the exposed specimens and the localization of structural changes in the thin surface layer of the exposed materials on surfaces in direct contact with the open space. Was investigated the elemental and molecular composition of the panel surface contaminations, which were caused by evaporation of components of the specimens of rubber materials. The data on the change in the strength of adhesive joints of different pairs of materials during their long-term operation in the space environment was obtained. Characteristics of the exposed specimens were compared with the control specimens, which were kept in laboratory conditions. According to the research of carbon plastic specimens with epoxy resin obtained experimental data on the stability of the macro and micro structure of carbon plastic, as well as a change in the strength characteristics after exposure. We obtain estimates of the influence of space factors on the carbon plastics structure and properties. By optical and electron microscopy were investigated craters on the surface of polished metal specimens and panels created by micrometeoroids and space debris impacts, as well as low-speed particles bonded to the surface. The elemental composition of substance in the craters and low-speed particles was determined, which enables to identify the origin of particles. The results obtained in the "Komplast" experiment allow giving a forecast changes in the properties of materials at their long-term operation in the ISS orbit. Are currently under exposure the remaining six panels "Komplast" on the surface of the FGB. Return and their detailed studying is considered in plans for further work.

Standard Reference Specimens in Quality Control of Engineering Surfaces

PubMed Central

Song, J. F.; Vorburger, T. V.

1991-01-01

In the quality control of engineering surfaces, we aim to understand and maintain a good relationship between the manufacturing process and surface function. This is achieved by controlling the surface texture. The control process involves: 1) learning the functional parameters and their control values through controlled experiments or through a long history of production and use; 2) maintaining high accuracy and reproducibility with measurements not only of roughness calibration specimens but also of real engineering parts. In this paper, the characteristics, utilizations, and limitations of different classes of precision roughness calibration specimens are described. A measuring procedure of engineering surfaces, based on the calibration procedure of roughness specimens at NIST, is proposed. This procedure involves utilization of check specimens with waveform, wavelength, and other roughness parameters similar to functioning engineering surfaces. These check specimens would be certified under standardized reference measuring conditions, or by a reference instrument, and could be used for overall checking of the measuring procedure and for maintaining accuracy and agreement in engineering surface measurement. The concept of “surface texture design” is also suggested, which involves designing the engineering surface texture, the manufacturing process, and the quality control procedure to meet the optimal functional needs. PMID:28184115

An analytical and experimental investigation of the response of the curved, composite frame/skin specimens

NASA Technical Reports Server (NTRS)

Moas, Eduardo; Boitnott, Richard L.; Griffin, O. Hayden, Jr.

1994-01-01

Six-foot diameter, semicircular graphite/epoxy specimens representative of generic aircraft frames were loaded quasi-statistically to determine their load response and failure mechanisms for large deflections that occur in airplanes crashes. These frame/skin specimens consisted of a cylindrical skin section co-cured with a semicircular I-frame. The skin provided the necessary lateral stiffness to keep deformations in the plane of the frame in order to realistically represent deformations as they occur in actual fuselage structures. Various frame laminate stacking sequences and geometries were evaluated by statically loading the specimen until multiple failures occurred. Two analytical methods were compared for modeling the frame/skin specimens: a two-dimensional shell finite element analysis and a one-dimensional, closed-form, curved beam solution derived using an energy method. Flange effectivities were included in the beam analysis to account for the curling phenomenon that occurs in thin flanges of curved beams. Good correlation was obtained between experimental results and the analytical predictions of the linear response of the frames prior to the initial failure. The specimens were found to be useful for evaluating composite frame designs.

Development of fracture mechanics data for two hydrazine APU turbine wheel materials

NASA Technical Reports Server (NTRS)

Curbishley, G.

1975-01-01

The effects of high temperature, high pressure ammonia were measured on the fracture mechanics and fatigue properties of Astroloy and Rene' 41 turbine wheel materials. Also, the influence of protective coatings on these properties was investigated. Specimens of forged bar stock were subjected to LCF and HCF tests at 950 K (1250 F) and 3.4 MN/sq m (500 psig) pressure, in ammonia containing about 1.5 percent H2O. Aluminized samples (Chromizing Company's Al-870) and gold plated test bars were compared with uncoated specimens. Comparison tests were also run in air at 950 K (1250 F), but at ambient pressures. K sub IE and K sub TH were determined on surface flawed specimens in both the air and ammonia in both uncoated and gold plated conditions. Gold plated specimens exhibited better properties than uncoated samples, and aluminized test bars generally had lower properties. The fatigue properties of specimens tested in ammonia were higher than those tested in air, yet the K sub TH values of ammonia tested samples were lower than those tested in air. However, insufficient specimens were tested to develop significant design data.

Test and Analysis Correlation for a Y-Joint Specimen for a Composite Cryotank

NASA Technical Reports Server (NTRS)

Mason, Brian H.; Sleight, David W.; Grenoble, Ray

2015-01-01

The Composite Cryotank Technology Demonstration (CCTD) project under NASA's Game Changing Development Program (GCDP) developed space technologies using advanced composite materials. Under CCTD, NASA funded the Boeing Company to design and test a number of element-level joint specimens as a precursor to a 2.4-m diameter composite cryotank. Preliminary analyses indicated that the y-joint in the cryotank had low margins of safety; hence the y-joint was considered to be a critical design region. The y-joint design includes a softening strip wedge to reduce localized shear stresses at the skirt/dome interface. In this paper, NASA-developed analytical models will be correlated with the experimental results of a series of positive-peel y-joint specimens from Boeing tests. Initial analytical models over-predicted the experimental strain gage readings in the far-field region by approximately 10%. The over-prediction was attributed to uncertainty in the elastic properties of the laminate and a mismatch between the thermal expansion of the strain gages and the laminate. The elastic properties of the analytical model were adjusted to account for the strain gage differences. The experimental strain gages also indicated a large non-linear effect in the softening strip region that was not predicted by the analytical model. This non-linear effect was attributed to delamination initiating in the softening strip region at below 20% of the failure load for the specimen. Because the specimen was contained in a thermally insulated box during cryogenic testing to failure, delamination initiation and progression was not visualized during the test. Several possible failure initiation locations were investigated, and a most likely failure scenario was determined that correlated well with the experimental data. The most likely failure scenario corresponded to damage initiating in the softening strip and delamination extending to the grips at final failure.

Studies on Muon Induction Acceleration and an Objective Lens Design for Transmission Muon Microscope

NASA Astrophysics Data System (ADS)

Artikova, Sayyora; Yoshida, Mitsuhiro; Naito, Fujio

Muon acceleration will be accomplished by a set of induction cells, where each increases the energy of the muon beam by an increment of up to 30 kV. The cells are arranged in a linear way resulting in total accelerating voltage of 300 kV. Acceleration time in the linac is about hundred nanoseconds. Induction field calculation is based on an electrostatic approximation. Beam dynamics in the induction accelerator is investigated and final beam focusing on specimen is realized by designing a pole piece lens.

Study of multilayer thermal insulation by inverse problems method

NASA Astrophysics Data System (ADS)

Alifanov, O. M.; Nenarokomov, A. V.; Gonzalez, V. M.

2009-11-01

The purpose of this paper is to introduce a new method in the research of radiative and thermal properties of materials with further applications in the design of thermal control systems (TCS) of spacecrafts. In this paper the radiative and thermal properties (emissivity and thermal conductance) of a multilayered thermal-insulating blanket (MLI), which is a screen-vacuum thermal insulation as a part of the TCS for perspective spacecrafts, are estimated. Properties of the materials under study are determined in the result of temperature and heat flux measurement data processing based on the solution of the inverse heat transfer problem (IHTP) technique. Given are physical and mathematical models of heat transfer processes in a specimen of the multilayered thermal-insulating blanket located in the experimental facility. A mathematical formulation of the inverse heat conduction problem is presented as well. The practical approves were made for specimen of the real MLI.

Evaluation of Pressurization Fatigue Life of 1441 Al-li Fuselage Panel

NASA Technical Reports Server (NTRS)

Bird, R. Keith; Dicus, Dennis I.; Fridlyander, Joseph; Davydov, Valentin

1999-01-01

A study was conducted to evaluate the pressurization fatigue life of fuselage panels with skins fabricated from 1441 Al-Li, an attractive new Russian alloy. The study indicated that 1441 Al-Li has several advantages over conventional aluminum fuselage skin alloy with respect to fatigue behavior. Smooth 1441 Al-Li sheet specimens exhibited a fatigue endurance limit similar to that for 1163 Al (Russian version of 2024 Al) sheet. Notched 1441 Al-Li sheet specimens exhibited greater fatigue strength and longer fatigue life than 1163 Al. In addition, Tu-204 fuselage panels fabricated by Tupolev Design Bureau using Al-Li skin and ring frames with riveted 7000-series aluminum stiffeners had longer pressurization fatigue lives than did panels constructed from conventional aluminum alloys. Taking into account the lower density of this alloy, the results suggest that 1441 Al-Li has the potential to improve fuselage performance while decreasing structural weight.

Quantifying the Impact of Additional Laboratory Tests on the Quality of a Geomechanical Model

NASA Astrophysics Data System (ADS)

Fillion, Marie-Hélène; Hadjigeorgiou, John

2017-05-01

In an open-pit mine operation, the design of safe and economically viable slopes can be significantly influenced by the quality and quantity of collected geomechanical data. In several mining jurisdictions, codes and standards are available for reporting exploration data, but similar codes or guidelines are not formally available or enforced for geotechnical design. Current recommendations suggest a target level of confidence in the rock mass properties used for slope design. As these guidelines are qualitative and somewhat subjective, questions arise regarding the minimum number of tests to perform in order to reach the proposed level of confidence. This paper investigates the impact of defining a priori the required number of laboratory tests to conduct on rock core samples based on the geomechanical database of an operating open-pit mine in South Africa. In this review, to illustrate the process, the focus is on uniaxial compressive strength properties. Available strength data for 2 project stages were analysed using the small-sampling theory and the confidence interval approach. The results showed that the number of specimens was too low to obtain a reliable strength value for some geotechnical domains even if more specimens than the minimum proposed by the ISRM suggested methods were tested. Furthermore, the testing sequence used has an impact on the minimum number of specimens required. Current best practice cannot capture all possibilities regarding the geomechanical property distributions, and there is a demonstrated need for a method to determine the minimum number of specimens required while minimising the influence of the testing sequence.

Structural Anomalies Detected in Ceramic Matrix Composites Using Combined Nondestructive Evaluation and Finite Element Analysis (NDE and FEA)

NASA Technical Reports Server (NTRS)

Abdul-Aziz, Ali; Baaklini, George Y.; Bhatt, Ramakrishna T.

2003-01-01

Most reverse engineering approaches involve imaging or digitizing an object and then creating a computerized reconstruction that can be integrated, in three dimensions, into a particular design environment. The rapid prototyping technique builds high-quality physical prototypes directly from computer-aided design files. This fundamental technique for interpreting and interacting with large data sets is being used here via Velocity2 (an integrated image-processing software, ref. 1) using computed tomography (CT) data to produce a prototype three-dimensional test specimen model for analyses. A study at the NASA Glenn Research Center proposes to use these capabilities to conduct a combined nondestructive evaluation (NDE) and finite element analysis (FEA) to screen pretest and posttest structural anomalies in structural components. A tensile specimen made of silicon nitrite (Si3N4) ceramic matrix composite was considered to evaluate structural durability and deformity. Ceramic matrix composites are being sought as candidate materials to replace nickel-base superalloys for turbine engine applications. They have the unique characteristics of being able to withstand higher operating temperatures and harsh combustion environments. In addition, their low densities relative to metals help reduce component mass (ref. 2). Detailed three-dimensional volume rendering of the tensile test specimen was successfully carried out with Velocity2 (ref. 1) using two-dimensional images that were generated via computed tomography. Subsequent, three-dimensional finite element analyses were performed, and the results obtained were compared with those predicted by NDE-based calculations and experimental tests. It was shown that Velocity2 software can be used to render a three-dimensional object from a series of CT scan images with a minimum level of complexity. The analytical results (ref. 3) show that the high-stress regions correlated well with the damage sites identified by the CT scans and the experimental data. Furthermore, modeling of the voids collected via NDE offered an analytical advantage that resulted in more accurate assessments of the material s structural strength. The top figure shows a CT scan image of the specimen test section illustrating various hidden structural entities in the material and an optical image of the test specimen considered in this study. The bottom figure represents the stress response predicted from the finite element analyses (ref .3 ) for a selected CT slice where it clearly illustrates the correspondence of the high stress risers due to voids in the material with those predicted by the NDE. This study is continuing, and efforts are concentrated on improving the modeling capabilities to imitate the structural anomalies as detected.

The biobank of the Norwegian mother and child cohort Study: A resource for the next 100 years

PubMed Central

Rønningen, Kjersti S.; Paltiel, Liv; Meltzer, Helle M.; Nordhagen, Rannveig; Lie, Kari K.; Hovengen, Ragnhild; Haugen, Margaretha; Nystad, Wenche; Magnus, Per; Hoppin, Jane A.

2007-01-01

Introduction Long-term storage of biological materials is a critical component of any epidemiological study. In designing specimen repositories, efforts need to balance future needs for samples with logistical constraints necessary to process and store samples in a timely fashion. Objectives In the Norwegian Mother and Child Cohort Study (MoBa), the Biobank was charged with long-term storage of more than 380,000 biological samples from pregnant women, their partners and their children for up to 100 years. Methods Biological specimens include whole blood, plasma, DNA and urine; samples are collected at 50 hospitals in Norway. All samples are sent via ordinary mail to the Biobank in Oslo where the samples are registered, aliquoted and DNA extracted. DNA is stored at −20 °C while whole blood, urine and plasma are stored at − 80 °C. Results As of July 2006, over 227,000 sample sets have been collected, processed and stored at the Biobank. Currently 250–300 sets are received daily. An important part of the Biobank is the quality control program. Conclusion With the unique combination of biological specimens and questionnaire data, the MoBa Study will constitute a resource for many future investigations of the separate and combined effects of genetic, environmental factors on pregnancy outcome and on human morbidity, mortality and health in general. PMID:17031521

Evaluation of Test Methods for Triaxially Braided Composites using a Meso-Scale Finite Element Model

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

Zhang, Chao

The characterization of triaxially braided composite is complicate due to the nonuniformity of deformation within the unit cell as well as the possibility of the freeedge effect related to the large size of the unit cell. Extensive experimental investigation has been conducted to develop more accurate test approaches in characterizing the actual mechanical properties of the material we are studying. In this work, a meso-scale finite element model is utilized to simulate two complex specimens: notched tensile specimen and tube tensile specimen, which are designed to avoid the free-edge effect and free-edge effect induced premature edge damage. The full fieldmore » strain data is predicted numerically and compared with experimental data obtained by Digit Image Correlation. The numerically predicted tensile strength values are compared with experimentally measured results. The discrepancy between numerically predicted and experimentally measured data, the capability of different test approaches are analyzed and discussed. The presented numerical model could serve as assistance to the evaluation of different test methods, and is especially useful in identifying potential local damage events.« less

Analysis on weathering characteristics of volcanic rocks in Dokdo, Korea based on accelerated weatehring experiments

NASA Astrophysics Data System (ADS)

Woo, Ik; Song, Won-Kyong; Kim, Bok-Chul; Kang, Jinseok

2010-05-01

Dokdo consists of small volcanic islands located in the southern part of the East Sea. Accelerated weathering tests was performed to examine the physico-mechanical characteristics of volcanic rocks in Dokdo. Rock core specimens of trachyandesite, andesitic dyke and ash tuff were prepared, and double soxhlet extractors(DSE) and peristatic pumps were used for accelerating the weathering processes. The DSE was designed to perform cyclic leaching tests for rock core specimen using distilled water at seventy degrees centigrade. The core specimens which are classified according to pre-test weathering grades placed in the lower part of the DSE, and periodically exposed to hot distilled water at every ninety minutes. On the other hand the peristatic pumps were utilized to induce leaching by distilled or brine water at normal temperature. The physico-mechanical property changes including rock surface appearance, microscopic structure and rock strength were analyzed with the results obtained from both experiments performed for 120 days. The conducted research in this study have shown that the methodologies of artificial weathering experiments have strong capability to understand the weathering characteristics of the rocks effectively.

Standard methods for filled hole tension testing of textile composites

NASA Technical Reports Server (NTRS)

Portanova, M. A.; Masters, J. E.

1995-01-01

The effects of two test specimen geometry parameters, the specimen width and W/D ratio, on filled-hole tensile strength were determined for textile composite materials. Test data generated by Boeing and Lockheed on 2-D and 3-D braids, and 3-D weaves were used to make these evaluations. The investigation indicated that filled-hole tensile-strength showed little sensitivity to either parameter. Test specimen configurations used in open-hole tension tests, such as those suggested by ASTM D5766 - Standard Test Method for Open Hole Tensile Strength of Polymer Matrix Composite Laminates or those proposed by MIL-HDBK-17-lD should provide adequate results for material comparisons studies. Comparisons of the materials' open-hole and filled-hole tensile strengths indicated that the latter were generally lower than the former. The 3-D braids were the exception; their filled-hole strengths were unexpected larger than their open-hole strengths. However, these increases were small compared to the scatter in the data. Thus, filled hole tension may be a critical design consideration for textile composite materials.

The seven deadly sins of DNA barcoding.

PubMed

Collins, R A; Cruickshank, R H

2013-11-01

Despite the broad benefits that DNA barcoding can bring to a diverse range of biological disciplines, a number of shortcomings still exist in terms of the experimental design of studies incorporating this approach. One underlying reason for this lies in the confusion that often exists between species discovery and specimen identification, and this is reflected in the way that hypotheses are generated and tested. Although these aims can be associated, they are quite distinct and require different methodological approaches, but their conflation has led to the frequently inappropriate use of commonly used analytical methods such as neighbour-joining trees, bootstrap resampling and fixed distance thresholds. Furthermore, the misidentification of voucher specimens can also have serious implications for end users of reference libraries such as the Barcode of Life Data Systems, and in this regard we advocate increased diligence in the a priori identification of specimens to be used for this purpose. This commentary provides an assessment of seven deficiencies that we identify as common in the DNA barcoding literature, and outline some potential improvements for its adaptation and adoption towards more reliable and accurate outcomes. © 2012 John Wiley & Sons Ltd.

T55-L-712 turbine engine compressor housing refurbishment-plasma spray project

NASA Technical Reports Server (NTRS)

Leissler, George W.; Yuhas, John S.

1988-01-01

A study was conducted to assess the feasibility of reclaiming T55-L-712 turbine engine compressor housings with an 88 wt percent aluminum to 12 wt percent silicon alloy applied by a plasma spray process. Tensile strength testing was conducted on as-sprayed and thermally cycled test specimens which were plasma sprayed with 0.020 to 0.100 in. coating thicknesses. Satisfactory tensile strength values were observed in the as-sprayed tensile specimens. There was essentially no decrease in tensile strength after thermally cycling the tensile specimens. Furthermore, compressor housings were plasma sprayed and thermally cycled in a 150-hr engine test and a 200-hr actual flight test during which the turbine engine was operated at a variety of loads, speeds and torques. The plasma sprayed coating system showed no evidence of degradation or delamination from the compressor housings. As a result of these tests, a procedure was designed and developed for the application of an aluminum-silicon alloy in order to reclaim T55-L-712 turbine engine compressor housings.

Shear Strength and Cracking Process of Non-persistent Jointed Rocks: An Extensive Experimental Investigation

NASA Astrophysics Data System (ADS)

Asadizadeh, Mostafa; Moosavi, Mahdi; Hossaini, Mohammad Farouq; Masoumi, Hossein

2018-02-01

In this paper, a number of artificial rock specimens with two parallel (stepped and coplanar) non-persistent joints were subjected to direct shearing. The effects of bridge length ( L), bridge angle ( γ), joint roughness coefficient (JRC) and normal stress ( σ n) on shear strength and cracking process of non-persistent jointed rock were studied extensively. The experimental program was designed based on Taguchi method, and the validity of the resulting data was assessed using analysis of variance. The results revealed that σ n and γ have the maximum and minimum effects on shear strength, respectively. Also, increase in L from 10 to 60 mm led to decrease in shear strength where high level of JRC profile and σ n led to the initiation of tensile cracks due to asperity interlocking. Such tensile cracks are known as "interlocking cracks" which normally initiate from the asperity and then propagate toward the specimen boundaries. Finally, the cracking process of specimens was classified into three categories, namely tensile cracking, shear cracking and combination of tension and shear or mixed mode tensile-shear cracking.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exporation

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. J.; Yerazunis, S. W.

1972-01-01

The problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars were investigated. Problem areas receiving attention include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis; navigation, terrain modeling and path selection; and chemical analysis of specimens. The following specific tasks were studied: vehicle model design, mathematical modeling of dynamic vehicle, experimental vehicle dynamics, obstacle negotiation, electromechanical controls, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer subsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, chromatograph model evaluation and improvement and transport parameter evaluation.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

NASA Technical Reports Server (NTRS)

Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Smith, E. J.; Yerazunis, S. W.

1972-01-01

Investigation of problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars has been undertaken. Problem areas receiving attention include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis; terrain modeling and path selection; and chemical analysis of specimens. The following specific tasks have been under study: vehicle model design, mathematical modeling of a dynamic vehicle, experimental vehicle dynamics, obstacle negotiation, electromechanical controls, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer sybsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, chromatograph model evaluation and improvement.

The Metacarpal Locked Intramedullary Nail: Comparative Biomechanical Evaluation of New Implant Design for Metacarpal Fractures.

PubMed

Boonyasirikool, Chinnakart; Tanakeatsakul, Sakkarin; Niempoog, Sunyarn

2015-04-01

The optimal fixation of metacarpal fracture should provide sufficient stability to permit early functionfor all types of fracture. However; it must preserve surrounding soft tissue during application and not require secondary removal due to its prominence. The prototype of metacarpal locked intramedullary nail (MCLN) was designed by our institute aiming to achieve those allfeatures. To biomechanically test our newly designed, locked metacarpal nail and compare with common current available fixation methods. Thirty chicken humeri were devided into 3 groups (n = 1 per group) according tofixation techniques: MCLN, 1.5 mm miniplate (Synthes), and Kirschner wire. After complete fixation, all specimens were osteotomized at mid-shaft creating transverse fractures. Five specimens from each group were tested by load of failure under axial compression, and another five under bending force. In axial compression model, the loads tofailure in MCLN group was greatest (460 ± 17 N), which was significant higher than the Kirschner wire group. The MCLN group also showed the highest load to failure in bending test (341 ± 10 N). This value reaches statistical significance when compared with plate and Kirschner wire groups. The MCLN construct provided higher stability than miniplate and Kirschner wire fixation both in axial and bending mode. Together with the minimally invasive and soft tissue-friendly design concept, this study suggests that MCLN is promising fixation option for metacarpal fracture.

Innovative real CSF leak simulation model for rhinology training: human cadaveric design.

PubMed

AlQahtani, Abdulaziz A; Albathi, Abeer A; Alhammad, Othman M; Alrabie, Abdulkarim S

2018-04-01

To study the feasibility of designing a human cadaveric simulation model of real CSF leak for rhinology training. The laboratory investigation took place at the surgical academic center of Prince Sultan Military Medical City between 2016 and 2017. Five heads of human cadaveric specimens were cannulated into the intradural space through two frontal bone holes. Fluorescein-dyed fluid was injected intracranialy, then endoscopic endonasal iatrogenic skull base defect was created with observation of fluid leak, followed by skull base reconstruction. The outcome measures included subjective assessment of integrity of the design, the ability of creating real CSF leak in multiple site of skull base and the possibility of watertight closure by various surgical techniques. The fluid filled the intradural space in all specimens without spontaneous leak from skull base or extra sinus areas. Successfully, we demonstrated fluid leak from all areas after iatrogenic defect in the cribriform plate, fovea ethmoidalis, planum sphenoidale sellar and clival regions. Watertight closure was achieved in all defects using different reconstruction techniques (overly, underlay and gasket seal closure). The design is simulating the real patient with CSF leak. It has potential in the learning process of acquiring and maintaining the surgical skills of skull base reconstruction before direct involvement of the patient. This model needs further evaluation and competence measurement as training tools in rhinology training.

Single-jet gas cooling of in-beam foils or specimens: Prediction of the convective heat-transfer coefficient

NASA Astrophysics Data System (ADS)

Steyn, Gideon; Vermeulen, Christiaan

2018-05-01

An experiment was designed to study the effect of the jet direction on convective heat-transfer coefficients in single-jet gas cooling of a small heated surface, such as typically induced by an accelerated ion beam on a thin foil or specimen. The hot spot was provided using a small electrically heated plate. Heat-transfer calculations were performed using simple empirical methods based on dimensional analysis as well as by means of an advanced computational fluid dynamics (CFD) code. The results provide an explanation for the observed turbulent cooling of a double-foil, Havar beam window with fast-flowing helium, located on a target station for radionuclide production with a 66 MeV proton beam at a cyclotron facility.

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.

Mechanical Properties of Degraded PMR-15 Resin

NASA Technical Reports Server (NTRS)

Tsuji, Luis C.; McManus, Hugh L.; Bowles, Kenneth J.

1998-01-01

Thermo-oxidative aging produces a non-uniform degradation state in PMR-15 resin. A surface layer, usually attributed to oxidative degradation, forms. This surface layer has different properties from the inner material. A set of material tests was designed to separate the properties of the oxidized surface layer from the properties of interior material. Test specimens were aged at 316 C in either air or nitrogen, for durations of up to 800 hours. The thickness of the oxidized surface layer in air aged specimens, and the shrinkage and Coefficient of Thermal Expansion (CTE) of nitrogen aged specimens were measured directly. Four-point-bend tests were performed to determine modulus of both the oxidized surface layer and the interior material. Bimaterial strip specimens consisting of oxidized surface material and unoxidized interior material were constructed and used to determine surface layer shrinkage and CTE. Results confirm that the surface layer and core materials have substantially different properties.

Scanning Electron Microscope Mapping System Developed for Detecting Surface Defects in Fatigue Specimens

NASA Technical Reports Server (NTRS)

Bonacuse, Peter J.; Kantzos, Peter T.

2002-01-01

An automated two-degree-of-freedom specimen positioning stage has been developed at the NASA Glenn Research Center to map and monitor defects in fatigue specimens. This system expedites the examination of the entire gauge section of fatigue specimens so that defects can be found using scanning electron microscopy (SEM). Translation and rotation stages are driven by microprocessor-based controllers that are, in turn, interfaced to a computer running custom-designed software. This system is currently being used to find and record the location of ceramic inclusions in powder metallurgy materials. The mapped inclusions are periodically examined during interrupted fatigue experiments. The number of cycles to initiate cracks from these inclusions and the rate of growth of initiated cracks can then be quantified. This information is necessary to quantify the effect of this type of defect on the durability of powder metallurgy materials. This system was developed with support of the Ultra Safe program.

Specimen plastic containers used to store expressed breast milk in neonatal care units: a case of precautionary principle.

PubMed

Blouin, Mélissa; Coulombe, Martin; Rhainds, Marc

2014-05-09

Breast milk is the only milk that meets both the nutritional and immunitary needs of infants. Since breastfeeding is widely promoted, public health measures to preserve the nutritional qualities of expressed breast milk (EBM) should be applied in hospital care settings. The Health Technology Assessment Unit (HTAU) of the Centre hospitalier universitaire de Québec was requested by the Neonatal Care Unit to assess the acceptability of a plastic specimen container, designed to harvest tissues and body fluids, for storing collected EBM. An evidence-based public health perspective approach was taken to evaluate the safety of the specimen container. The HTAU recommended that plastic specimen containers no longer be used for storing EBM and that other options should be evaluated for neonatal care units. These recommendations are in accordance with the public health precaution principle and with legal considerations.

Manufacture of fiber-epoxy test specimens: Including associated jigs and instrumentation

NASA Technical Reports Server (NTRS)

Mathur, S. B.; Felbeck, D. K.

1980-01-01

Experimental work on the manufacture and strength of graphite-epoxy composites is considered. The correct data and thus a true assessment of the strength properties based on a proper and scientifically modeled test specimen with engineered design, construction, and manufacture has led to claims of a very broad spread in optimized values. Such behavior is in the main due to inadequate control during manufacture of test specimen, improper curing, and uneven scatter in the fiber orientation. The graphite fibers are strong but brittle. Even with various epoxy matrices and volume fraction, the fracture toughness is still relatively low. Graphite-epoxy prepreg tape was investigated as a sandwich construction with intermittent interlaminar bonding between the laminates in order to produce high strength, high fracture toughness composites. The quality and control of manufacture of the multilaminate test specimen blanks was emphasized. The dimensions, orientation and cure must be meticulous in order to produce the desired mix.

Pure moment testing for spinal biomechanics applications: fixed versus 3D floating ring cable-driven test designs.

PubMed

Tang, Jessica A; Scheer, Justin K; Ames, Christopher P; Buckley, Jenni M

2012-02-23

Pure moment testing has become a standard protocol for in vitro assessment of the effect of surgical techniques or devices on the bending rigidity of the spine. Of the methods used for pure moment testing, cable-driven set-ups are popular due to their low requirements and simple design. Fixed loading rings are traditionally used in conjunction with these cable-driven systems. However, the accuracy and validity of the loading conditions applied with fixed ring designs have raised some concern, and discrepancies have been found between intended and prescribed loading conditions for flexion-extension. This study extends this prior work to include lateral bending and axial torsion, and compares this fixed ring design with a novel "3D floating ring" design. A complete battery of multi-axial bending tests was conducted with both rings in multiple different configurations using an artificial lumbar spine. Applied moments were monitored and recorded by a multi-axial load cell at the base of the specimen. Results indicate that the fixed ring design deviates as much as 77% from intended moments and induces non-trivial shear forces (up to 18 N) when loaded to a non-destructive maximum of 4.5 Nm. The novel 3D floating ring design largely corrects the inherent errors in the fixed ring design by allowing additional directions of unconstrained motion and producing uniform loading conditions along the length of the specimen. In light of the results, it is suggested that the 3D floating ring set-up be used for future pure moment spine biomechanics applications using a cable-driven apparatus. Copyright © 2012 Elsevier Ltd. All rights reserved.

Development of a Priest interferometer for measurement of the thermal expansion of a graphite epoxy in the temperature range 116-366 K

NASA Technical Reports Server (NTRS)

Short, J. S.; Hyer, M. W.; Bowles, D. E.; Tompkins, S. S.

1982-01-01

The thermal expansion behavior of graphite epoxy laminates between 116 and 366 degrees Kelvin was investigated using as implementation of the Priest interferometer concept. The design, construction and use of the interferometer along with the experimental results it was used to generate are described. The experimental program consisted of 25 tests on 25.4 mm and 6.35 mm wide, 8 ply pi/4 quasi-isotropic T300-5208 graphite/epoxy specimens and 3 tests on a 25.4 mm wide unidirectional specimen. Experimental results are presented for all tests along with a discussion of the interferometer's limitations and some possible improvements in its design.

Analysis of polyethylene terephthalate PET plastic bottle jointing system using finite element method (FEM)

NASA Astrophysics Data System (ADS)

Zaidi, N. A.; Rosli, Muhamad Farizuan; Effendi, M. S. M.; Abdullah, Mohamad Hariri

2017-09-01

For almost all injection molding applications of Polyethylene Terephthalate (PET) plastic was analyzed the strength, durability and stiffness of properties by using Finite Element Method (FEM) for jointing system of wood furniture. The FEM was utilized for analyzing the PET jointing system for Oak and Pine as wood based material of furniture. The difference pattern design of PET as wood jointing furniture gives the difference value of strength furniture itself. The results show the wood specimen with grooves and eclipse pattern design PET jointing give lower global estimated error is 28.90%, compare to the rectangular and non-grooves wood specimen of global estimated error is 63.21%.

Fabrication and evaluation of advanced titanium structural panels for supersonic cruise aircraft

NASA Technical Reports Server (NTRS)

Payne, L.

1977-01-01

Flightworthy primary structural panels were designed, fabricated, and tested to investigate two advanced fabrication methods for titanium alloys. Skin-stringer panels fabricated using the weldbraze process, and honeycomb-core sandwich panels fabricated using a diffusion bonding process, were designed to replace an existing integrally stiffened shear panel on the upper wing surface of the NASA YF-12 research aircraft. The investigation included ground testing and Mach 3 flight testing of full-scale panels, and laboratory testing of representative structural element specimens. Test results obtained on full-scale panels and structural element specimens indicate that both of the fabrication methods investigated are suitable for primary structural applications on future civil and military supersonic cruise aircraft.

Specimen coordinate automated measuring machine/fiducial automated measuring machine

DOEpatents

Hedglen, Robert E.; Jacket, Howard S.; Schwartz, Allan I.

1991-01-01

The Specimen coordinate Automated Measuring Machine (SCAMM) and the Fiducial Automated Measuring Machine (FAMM) is a computer controlled metrology system capable of measuring length, width, and thickness, and of locating fiducial marks. SCAMM and FAMM have many similarities in their designs, and they can be converted from one to the other without taking them out of the hot cell. Both have means for: supporting a plurality of samples and a standard; controlling the movement of the samples in the +/- X and Y directions; determining the coordinates of the sample; compensating for temperature effects; and verifying the accuracy of the measurements and repeating as necessary. SCAMM and FAMM are designed to be used in hot cells.

21 CFR 58.51 - Specimen and data storage facilities.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Specimen and data storage facilities. 58.51..., for the storage and retrieval of all raw data and specimens from completed studies. ... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Facilities § 58.51 Specimen and data...

21 CFR 58.51 - Specimen and data storage facilities.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Specimen and data storage facilities. 58.51..., for the storage and retrieval of all raw data and specimens from completed studies. ... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Facilities § 58.51 Specimen and data...

21 CFR 58.51 - Specimen and data storage facilities.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Specimen and data storage facilities. 58.51..., for the storage and retrieval of all raw data and specimens from completed studies. ... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Facilities § 58.51 Specimen and data...

21 CFR 58.51 - Specimen and data storage facilities.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Specimen and data storage facilities. 58.51..., for the storage and retrieval of all raw data and specimens from completed studies. ... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Facilities § 58.51 Specimen and data...

21 CFR 58.51 - Specimen and data storage facilities.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Specimen and data storage facilities. 58.51..., for the storage and retrieval of all raw data and specimens from completed studies. ... GOOD LABORATORY PRACTICE FOR NONCLINICAL LABORATORY STUDIES Facilities § 58.51 Specimen and data...

Histologic processing and reporting of cutaneous pigmented lesions: recommendations based on a survey of 94 dermatopathologists.

PubMed

Kolman, Olga; Hoang, Mai P; Piris, Adriano; Mihm, Martin C; Duncan, Lyn M

2010-10-01

Standard operating procedures for laboratory processing and reporting of margins of cutaneous pigmented lesions do not exist. We conducted a survey of 94 dermatopathologists to evaluate these practices. We sought to: (1) identify dominant practices among dermatopathologists; (2) determine the impact of the procedure, intent to excise, and histologic diagnosis on the process of margin evaluation; and (3) propose guidelines based on these findings. The survey consisted of 44 questions focused on the impact of procedure (punch, shave, or ellipse), intent (excision or biopsy), and histologic diagnosis (common nevus, congenital nevus, atypical nevus, melanoma) on processing and margin reporting. For ellipses, or specimens indicated as excisions, the majority practice (76%-98%) was to ink the specimens. Although more than 90% of observers report the margins on all melanomas and atypical nevi, fewer than 50% of respondents report margins on all nonatypical nevi. The study consists of a survey sample of dermatopathologists and does not represent the practices of those who did not respond to the survey. Based on the results of this survey we have arrived at the following recommendations: (1) ink all specimens that are ellipses or designated as excisions; (2) tips should be evaluated separately if the specimen is an ellipse; (3) obtain levels in cases with tumor in the tip but not at ink if the specimen is an ellipse or excision and the diagnosis is atypical nevus or melanoma; and (4) report margins on all atypical nevi and melanomas. Copyright © 2009 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

The complimentary use of evacuable cells and remote sensing accessories for materials characterization by FT-IR spectroscopy

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

Powell, G.L.; Milosevic, M.

Diffuse reflectance (DR), emission (E), and external reflectance (ER) FT-IR spectroscopies are powerful techniques for materials characterization and surface analysis provided the spectrometer can address the appropriate location on a specimen under conditions for which the resulting measurement is meaningful. Evacuable cells and transfer optics have been developed for this purpose for coupon studies under laboratory conditions where a well defined location on a specimen can be monitored by DR, E, or ER while the environment, i. e., temperature and atmosphere, of the specimen is rigorously controlled. The Spectropus system of remote sampling accessories has been developed to make similarmore » measurements on large flat or convex objects in ambient air or in environmental chambers with sufficient ease that meaningful statistical comparisons of spectra obtained from many locations on a specimen or from many specimens can be made. These two general techniques are complimentary and allow for the results of controlled laboratory experiments to be readily extended to inspection operations. Evacuable cells designs for DR, for combined DR and E, and for 75{degrees}-ER with polarized light are described. Complimentary use of these cells with functionally similar remote sensing accessories is demonstrated with applications including the preparation of ceramic BeO surfaces for adhesive bonding (DR), the determination of the extent of cure and the oxidative degradation of epoxy adhesives and composites (DR and E), and the determination of the oxidation rate of uranium metal in air, oxygen, and water vapor (ER).« less

LifeSat - A new research vehicle

NASA Technical Reports Server (NTRS)

Gilbreath, William P.; Dunning, Robert W.

1990-01-01

LifeSat is a reusable recoverable satellite that will support research in the gravitation and radiation biology fields. It can provide sustained lower gravitational levels than manned vehicles and can access orbits where specimens can be exposed to cosmic radiation. The satellite design encompasses environmental support for vertebrate, invertebrate and plant specimens ranging from cells and tissues up to small mammals. The first launch, in a series of 7 satellite flights, is planned for late 1995.

Design and implementation of an external quality assessment program for HIV viral load measurements using dried blood spots.

PubMed

Prach, Lisa M; Puren, Adrian; Lippman, Sheri A; Carmona, Sergio; Stephenson, Sophie; Cutler, Ewalde; Barnhart, Scott; Liegler, Teri

2015-03-01

An external quality assurance program was developed for HIV-1 RNA viral load measurements taken from dried blood spots using a reference panel and field-collected specimens. The program demonstrated that accurate and reproducible quantitation can be obtained from field-collected specimens. Residual proviral DNA may confound interpretation in virologically suppressed subjects. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Development and Testing of a Single Frequency Terahertz Imaging System for Breast Cancer Detection

PubMed Central

St. Peter, Benjamin; Yngvesson, Sigfrid; Siqueira, Paul; Kelly, Patrick; Khan, Ashraf; Glick, Stephen; Karellas, Andrew

2013-01-01

The ability to discern malignant from benign tissue in excised human breast specimens in Breast Conservation Surgery (BCS) was evaluated using single frequency terahertz radiation. Terahertz (THz) images of the specimens in reflection mode were obtained by employing a gas laser source and mechanical scanning. The images were correlated with optical histological micrographs of the same specimens, and a mean discrimination of 73% was found for five out of six samples using Receiver Operating Characteristic (ROC) analysis. The system design and characterization is discussed in detail. The initial results are encouraging but further development of the technology and clinical evaluation is needed to evaluate its feasibility in the clinical environment. PMID:25055306

Life prediction and constitutive models for engine hot section anisotropic materials

NASA Technical Reports Server (NTRS)

Swanson, G. A.

1984-01-01

The development of directionally solidified and single crystal alloys is perhaps the most important recent advancement in hot section materials technology. The objective is to develop knowledge that enables the designer to improve anisotropic gas turbine parts to their full potential. Two single crystal alloys selected were PWA 1480 and Alloy 185. The coatings selected were an overlay coating, PWA 286, and an aluminide diffusion coating, PWA 273. The constitutive specimens were solid and cylindrical; the fatigue specimens were hollow and cylindrical. Two thicknesses of substrate are utilized. Specimens of both thickness (0.4 and 1.5 mm) will be coated and then tested for tensile, creep, and fatigue properties.

The type material of Mantodea (praying mantises) deposited in the National Museum of Natural History, Smithsonian Institution, USA

PubMed Central

Svenson, Gavin J.

2014-01-01

Abstract The collection of Mantodea of the National Museum of Natural History, Smithsonian Institution, includes 26 holotypes, 7 allotypes, 4 lectotypes, 23 paratypes, and 1 paralectotype. Four type specimens were designated as lectotypes within this work. Highly accurate measurement data, high resolution images of specimens and labels, verbatim label data, georeferenced coordinates, original and newly assigned database codes, and bibliographic data are presented for all primary types. Label data for all paratype specimens in the collection are provide in tabular form. The location of the USNM collection has been moved to the Cleveland Museum of Natural History as a loan under the Off-site Enhancement Program. PMID:25152673

In-line assay monitor for uranium hexafluoride

DOEpatents

Wallace, Steven A.

1981-01-01

An in-line assay monitor for determining the content of uranium-235 in a uranium hexafluoride gas isotopic separation system is provided which removes the necessity of complete access to the operating parameters of the system for determining the uranium-235 content. The monitor is intended for uses such as safeguard applications to assure that weapons grade uranium is not being produced in an enrichment cascade. The method and monitor for carrying out the method involve cooling of a radiation pervious chamber connected in fluid communication with the selected point in the system to withdraw a specimen and solidify the specimen in the chamber. The specimen is irradiated by means of an ionizing radiation source of energy different from that of the 185 keV gamma emissions from the uranium-235 present in the specimen. Simultaneously, the gamma emissions from the uranium-235 of the specimen and the source emissions transmitted through the sample are counted and stored in a multiple channel analyzer. The uranium-235 content of the specimen is determined from the comparison of the accumulated 185 keV energy counts and the reference energy counts. The latter is used to measure the total uranium isotopic content of the specimen. The process eliminates the necessity of knowing the system operating conditions and yet obtains the necessary data without need for large scintillation crystals and sophisticated mechanical designs.

Experimental and analytical studies on the seismic behavior of conventional and hybrid braced frames

NASA Astrophysics Data System (ADS)

Lai, Jiun-Wei

This dissertation summarizes both experimental and analytical studies on the seismic response of conventional steel concentrically braced frame systems of the type widely used in North America, and preliminary studies of an innovative hybrid braced frame system: the Strong-Back System. The research work is part of NEES small group project entitled "International Hybrid Simulation of Tomorrow's Braced Frames." In the experimental phase, a total of four full-scale, one-bay, two-story conventional braced frame specimens with different bracing member section shapes and gusset plate-to-beam connection details were designed and tested at the NEES Berkeley Laboratory. Three braced frame specimens were tested quasi-statically using the same predefined loading protocol to investigate the inelastic cyclic behavior of code-compliant braced frames at both the global and local level. The last braced frame specimen was nearly identical to one of those tested quasi-statically. However, it was tested using hybrid simulation techniques to examine the sensitivity of inelastic behavior on loading sequence and to relate the behavior observed to different levels of seismic hazard. Computer models of the test specimens were developed using two different computer software programs. In the software framework OpenSees fiber-based line elements were used to simulate global buckling of members and yielding and low-cycle fatigue failure at sections. The LS-DYNA analysis program was also used to model individual struts and the test specimens using shell elements with adaptive meshing and element erosion features. This program provided enhanced ability to simulate section local buckling, strain concentrations and crack development. The numerical results were compared with test results to assess and refine and the ability of the models to predict braced frame behavior. A series of OpenSees numerical cyclic component simulations were then conducted using the validated modeling approach. Two hundred and forty pin-ended struts with square hollow structural section shape were simulated under cyclic loading to examine the effect of width-to-thickness ratios and member slenderness ratios on the deformation capacity and energy dissipation characteristics of brace members. The concept of a hybrid system, consisting of a vertical elastic truss or strong-back, and a braced frame that responds inelastically, is proposed herein to mitigate the tendency of weak-story mechanisms to form in conventional steel braced frames. A simple design strategy about member sizing of the proposed Strong-Back System is provided in this study. To assess the ability of the new Strong-Back System to perform well under seismic loading, a series of inelastic analyses were performed considering three six-story hybrid braced frames having different bracing elements, and three six-story conventional brace frames having different brace configurations. Monotonic and cyclic quasi-static inelastic analyses and inelastic time history analyses were carried out. The braced frame system behavior, bracing member force-displacement hysteresis loops, and system residual drifts were the primary response quantities examined. These indicated that the new hybrid system was able to achieve its design goals. Experimental results show for the same loading history that the braced frame specimen using round hollow structural sections as brace members has the largest deformation capacity among the three types of bracing elements studied. Beams connected to gusset plates at the column formed plastic hinges adjacent to the gusset plate. The gusset plates tend to amplify the rotation demands at these locations and stress concentrations tended to result in early fractures of the plastic hinges that form. To remedy this problem, pinned connection details used in the last two specimens; these proved to prevent failures at these locations under both quasi-static and pseudo-dynamic tests. Failure modes observed near the column to base plate connections in all of the specimens suggest the need for further study. Both OpenSees and LS-DYNA models developed in this study predict the global braced frame behavior with acceptable accuracy. In both models, low-cycle fatigue damage models were needed to achieve an acceptable level of fidelity. Shell element models were able to predict local behavior and the mode of failures with greater but not perfect confidence. OpenSees analysis results show that the proposed hybrid braced frames would perform better than conventional braced frames and that the story deformations are more uniform. Finally, future research targets are briefly discussed at the end of this dissertation.

Redescription, lectotype designation and new records of Anastrepha luederwaldti Lima (Diptera, Tephritidae)

USDA-ARS?s Scientific Manuscript database

The previously poorly known species Anastrepha luederwaldti Lima, 1934 is redescribed based on a reexamination of the syntypes from São Paulo and additional specimens from Santa Catarina and Rio Grande do Sul, Brazil. A lectotype is designated....

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...

Hypervelocity Impact Test Results for a Metallic Thermal Protection System

NASA Technical Reports Server (NTRS)

Karr, Katherine L.; Poteet, Carl C.; Blosser, Max L.

2003-01-01

Hypervelocity impact tests have been performed on specimens representing metallic thermal protection systems (TPS) developed at NASA Langley Research Center for use on next-generation reusable launch vehicles (RLV). The majority of the specimens tested consists of a foil gauge exterior honeycomb panel, composed of either Inconel 617 or Ti-6Al-4V, backed with 2.0 in. of fibrous insulation and a final Ti-6Al-4V foil layer. Other tested specimens include titanium multi-wall sandwich coupons as well as TPS using a second honeycomb sandwich in place of the foil backing. Hypervelocity impact tests were performed at the NASA Marshall Space Flight Center Orbital Debris Simulation Facility. An improved test fixture was designed and fabricated to hold specimens firmly in place during impact. Projectile diameter, honeycomb sandwich material, honeycomb sandwich facesheet thickness, and honeycomb core cell size were examined to determine the influence of TPS configuration on the level of protection provided to the substructure (crew, cabin, fuel tank, etc.) against micrometeoroid or orbit debris impacts. Pictures and descriptions of the damage to each specimen are included.

Dual Priming Oligonucleotides for Broad-Range Amplification of the Bacterial 16S rRNA Gene Directly from Human Clinical Specimens

PubMed Central

Simmon, Keith; Karaca, Dilek; Langeland, Nina; Wiker, Harald G.

2012-01-01

Broad-range amplification and sequencing of the bacterial 16S rRNA gene directly from clinical specimens are offered as a diagnostic service in many laboratories. One major pitfall is primer cross-reactivity with human DNA which will result in mixed chromatograms. Mixed chromatograms will complicate subsequent sequence analysis and impede identification. In SYBR green real-time PCR assays, it can also affect crossing threshold values and consequently the status of a specimen as positive or negative. We evaluated two conventional primer pairs in common use and a new primer pair based on the dual priming oligonucleotide (DPO) principle. Cross-reactivity was observed when both conventional primer pairs were used, resulting in interpretation difficulties. No cross-reactivity was observed using the DPOs even in specimens with a high ratio of human to bacterial DNA. In addition to reducing cross-reactivity, the DPO principle also offers a high degree of flexibility in the design of primers and should be considered for any PCR assay intended for detection and identification of pathogens directly from human clinical specimens. PMID:22278843

Breast Cancer Research at NASA

NASA Technical Reports Server (NTRS)

1998-01-01

Breast tissue specimens in traditional sample dishes. NASA's Marshall Space Flight Center (MSFC) is sponsoring research with Bioreactors, rotating wall vessels designed to grow tissue samples in space, to understand how breast cancer works. This ground-based work studies the growth and assembly of human mammary epithelial cells (HMEC) from breast cancer susceptible tissue. Radiation can make the cells cancerous, thus allowing better comparisons of healthy vs. tunourous tissues.

Electrospun Fibers for Composites Applications

DTIC Science & Technology

2014-02-01

so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an official endorsement or approval of...and tensile testing . While the nanofibers did not dramatically stiffen the resulting composites, they provided insight as to the impact of the...of suitable fiber mats for this study limited the scope and accessibility of test specimens, the results from the examination of fiber-matrix

Effects of floor location on response of composite fuselage frames

NASA Technical Reports Server (NTRS)

Carden, Huey D.; Jones, Lisa E.; Fasanella, Edwin L.

1992-01-01

Experimental and analytical results are presented which show the effect of floor placement on the structural response and strength of circular fuselage frames constructed of graphite-epoxy composite material. The research was conducted to study the behavior of conventionally designed advanced composite aircraft components. To achieve desired new designs which incorporate improved energy absorption capabilities requires an understanding of how these conventional designs behave under crash type loadings. Data are presented on the static behavior of the composite structure through photographs of the frame specimen, experimental strain distributions, and through analytical data from composite structural models. An understanding of this behavior can aid the dynamist in predicting the crash behavior of these structures and may assist the designer in achieving improved designs for energy absorption and crash behavior of future structures.

M3FT-16OR0203052-Test Design for FeCrAl Alloy Tube Irradiation in HFIR

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

Terrani, Kurt A.; Petrie, Christian M.

2016-05-01

This calculation summarizes thermal analyses of a flexible rabbit design for irradiating a variety of pressurized water reactor (PWR) cladding materials (stainless steel, iron-chromium aluminum [FeCrAl], Zircaloy, and Inconel) with variable dimensions at a temperature of 350 °C in the flux trap of the High Flux Isotope Reactor (HFIR). The design can accommodate standard cladding for outer diameters (ODs) of approximately 9.50 mm with thickness ranging from 0.30 mm to 0.70 mm. The length is generally between 10 and 50 mm. The specimens contain moly inserts with a variable OD that provides the heat flux necessary to achieve the designmore » temperature with such a small fixed gas gap. The primary outer containment is an Al-6061 housing with a slightly enlarged inner diameter (ID) of 9.60 mm. The specimen temperature is controlled by determining a helium/argon gas mixture specific to the as-built specimen and housing. Variables that affect the required gas mixture are the cladding material (thermal expansion, density, heat generation rate), cladding OD, housing ID, and cladding ID. This calculation documents the analyses performed to determine required gas mixtures for a variety of scenarios.« less

Rediscovery of the type series of the Acadian Masked Shrew, Sorex acadicus Gilpin, 1865 (Mammalia: Soricidae), with the designation of a neotype and a reevaluation of its taxonomic status

USGS Publications Warehouse

Woodman, Neal

2018-01-01

The name Sorex acadicus Gilpin, 1865 is currently recognized as the valid name for the Nova Scotian subspecies of the masked shrew, S. cinereus Kerr, 1792 (Mammalia: Soricidae), but a holotype for the taxon was never designated, and the location of the type series has been a mystery. The authority for this species, John Bernard Gilpin, was associated with the Nova Scotia Museum, Halifax, NS, but that institution has no Gilpin specimens in its possession, and I could find no record of Gilpin shrews in any other Canadian Museum. I recently discovered a series of Gilpin specimens in the Mammal Collection of the National Museum of Natural History, Washington, DC (USNM), some of which may have been part of the original type series of S. acadicus, and I show that these specimens best represent Gilpin's concept of the taxon. From this series, I designate a neotype for S. acadicus. I also evaluate the distinctiveness of Nova Scotian S. c. acadicus compared with S. c. cinereus from Maine, New Brunswick, and New Hampshire and determine that S. acadicus should be considered a junior synonym of S. c. cinereus.

Fracture toughness and Charpy impact properties of several RAFMS before and after irradiation in HFIR

NASA Astrophysics Data System (ADS)

Sokolov, M. A.; Tanigawa, H.; Odette, G. R.; Shiba, K.; Klueh, R. L.

2007-08-01

As part of the development of candidate reduced-activation ferritic steels for fusion applications, several steels, namely F82H, 9Cr-2WVTa steels and F82H weld metal, are being investigated in the joint DOE-JAEA collaboration program. Within this program, three capsules containing a variety of specimen designs were irradiated at two design temperatures in the ORNL High Flux Isotope Reactor (HFIR). Two capsules, RB-11J and RB-12J, were irradiated in the HFIR removable beryllium positions with europium oxide (Eu 2O 3) thermal neutron shields in place. Specimens were irradiated up to 5 dpa. Capsule JP25 was irradiated in the HFIR target position to 20 dpa. The design temperatures were 300 °C and 500 °C. Precracked third-sized V-notch Charpy (3.3 × 3.3 × 25.4 mm) and 0.18 T DC(T) specimens were tested to determine transition and ductile shelf fracture toughness before and after irradiation. The master curve methodology was applied to evaluate the fracture toughness transition temperature, T0. Irradiation induced shifts of T0 and reductions of JQ were compared with Charpy V-notch impact properties. Fracture toughness and Charpy shifts were also compared to hardening results.

Laser-scanned fluorescence of nonlased/normal, lased/normal, nonlased/carious, and lased/carious enamel

NASA Astrophysics Data System (ADS)

Zakariasen, Kenneth L.; Barron, Joseph R.; Paton, Barry E.

1992-06-01

Research has shown that low levels of CO2 laser irradiation raise enamel resistance to sub-surface demineralization. Additionally, laser scanned fluorescence analysis of enamel, as well a laser and white light reflection studies, have potential for both clinical diagnosis and comparative research investigations of the caries process. This study was designed to compare laser fluorescence and laser/white light reflection of (1) non-lased/normal with lased/normal enamel and (2) non-lased/normal with non-lased/carious and lased/carious enamel. Specimens were buccal surfaces of extracted third molars, coated with acid resistant varnish except for either two or three 2.25 mm2 windows (two window specimens: non-lased/normal, lased/normal--three window specimens: non-lased/normal, non-lased carious, lased/carious). Teeth exhibiting carious windows were immersed in a demineralizing solution for twelve days. Non-carious windows were covered with wax during immersion. Following immersion, the wax was removed, and fluorescence and laser/white light reflection analyses were performed on all windows utilizing a custom scanning laser fluorescence spectrometer which focuses light from a 25 mWatt He-Cd laser at 442 nm through an objective lens onto a cross-section >= 3 (mu) in diameter. For laser/white light reflection analyses, reflected light intensities were measured. A HeNe laser was used for laser light reflection studies. Following analyses, the teeth are sectioned bucco-lingually into 80 micrometers sections, examined under polarized light microscopy, and the lesions photographed. This permits comparison between fluorescence/reflected light values and the visualized decalcification areas for each section, and thus comparisons between various enamel treatments and normal enamel. The enamel specimens are currently being analyzed.

Numerical simulation of a relaxation test designed to fit a quasi-linear viscoelastic model for temporomandibular joint discs.

PubMed

Commisso, Maria S; Martínez-Reina, Javier; Mayo, Juana; Domínguez, Jaime

2013-02-01

The main objectives of this work are: (a) to introduce an algorithm for adjusting the quasi-linear viscoelastic model to fit a material using a stress relaxation test and (b) to validate a protocol for performing such tests in temporomandibular joint discs. This algorithm is intended for fitting the Prony series coefficients and the hyperelastic constants of the quasi-linear viscoelastic model by considering that the relaxation test is performed with an initial ramp loading at a certain rate. This algorithm was validated before being applied to achieve the second objective. Generally, the complete three-dimensional formulation of the quasi-linear viscoelastic model is very complex. Therefore, it is necessary to design an experimental test to ensure a simple stress state, such as uniaxial compression to facilitate obtaining the viscoelastic properties. This work provides some recommendations about the experimental setup, which are important to follow, as an inadequate setup could produce a stress state far from uniaxial, thus, distorting the material constants determined from the experiment. The test considered is a stress relaxation test using unconfined compression performed in cylindrical specimens extracted from temporomandibular joint discs. To validate the experimental protocol, the test was numerically simulated using finite-element modelling. The disc was arbitrarily assigned a set of quasi-linear viscoelastic constants (c1) in the finite-element model. Another set of constants (c2) was obtained by fitting the results of the simulated test with the proposed algorithm. The deviation of constants c2 from constants c1 measures how far the stresses are from the uniaxial state. The effects of the following features of the experimental setup on this deviation have been analysed: (a) the friction coefficient between the compression plates and the specimen (which should be as low as possible); (b) the portion of the specimen glued to the compression plates (smaller areas glued are better); and (c) the variation in the thickness of the specimen. The specimen's faces should be parallel to ensure a uniaxial stress state. However, this is not possible in real specimens, and a criterion must be defined to accept the specimen in terms of the specimen's thickness variation and the deviation of the fitted constants arising from such a variation.

A Study on the Influence of Process Parameters on the Viscoelastic Properties of ABS Components Manufactured by FDM Process

NASA Astrophysics Data System (ADS)

Dakshinamurthy, Devika; Gupta, Srinivasa

2018-04-01

Fused Deposition Modelling (FDM) is a fast growing Rapid Prototyping (RP) technology due to its ability to build parts having complex geometrical shape in reasonable time period. The quality of built parts depends on many process variables. In this study, the influence of three FDM process parameters namely, slice height, raster angle and raster width on viscoelastic properties of Acrylonitrile Butadiene Styrene (ABS) RP-specimen is studied. Statistically designed experiments have been conducted for finding the optimum process parameter setting for enhancing the storage modulus. Dynamic Mechanical Analysis has been used to understand the viscoelastic properties at various parameter settings. At the optimal parameter setting the storage modulus and loss modulus of the ABS-RP specimen was 1008 and 259.9 MPa respectively. The relative percentage contribution of slice height and raster width on the viscoelastic properties of the FDM-RP components was found to be 55 and 31 % respectively.

Progress Report on Alloy 617 Notched Specimen Testing

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

McMurtrey, Michael David; Wright, Richard Neil; Lillo, Thomas Martin

Creep behavior of Alloy 617 has been extensively characterized to support the development of a draft Code Case to qualify Alloy 617 in Section III division 5 of the ASME Boiler and Pressure Vessel Code. This will allow use of Alloy 617 in construction of nuclear reactor components at elevated temperatures and longer periods of time (up to 950°C and 100,000 hours). Prior to actual use, additional concerns not considered in the ASME code need to be addressed. Code Cases are based largely on uniaxial testing of smooth gage specimens. In service conditions, components will generally be under multi axialmore » loading. There is also the concern of the behavior at discontinuities, such as threaded components. To address the concerns of multi axial creep behavior and at geometric discontinuities, notched specimens have been designed to create conditions representative of the states that service components experience. Two general notch geometries have been used for these series of tests: U notch and V notch specimens. The notches produce a tri axial stress state, though not uniform across the specimen. Characterization of the creep behavior of the U notch specimens and the creep rupture behavior of the V notch specimens provides a good approximation of the behavior expected of actual components. Preliminary testing and analysis have been completed and are reported in this document. This includes results from V notch specimens tested at 900°C and 800°C. Failure occurred in the smooth gage section of the specimen rather than at the root of the notch, though some damage was present at the root of the notch, where initial stress was highest. This indicates notch strengthening behavior in this material at these temperatures.« less

Experimental Study on Welded Headed Studs Used In Steel Plate-Concrete Composite Structures Compared with Contactless Method of Measuring Displacement

NASA Astrophysics Data System (ADS)

Kisała, Dawid; Tekieli, Marcin

2017-10-01

Steel plate-concrete composite structures are a new innovative design concept in which a thin steel plate is attached to the reinforced concrete beam by means of welded headed studs. The comparison between experimental studies and theoretical analysis of this type of structures shows that their behaviour is dependent on the load-slip relationship of the shear connectors used to ensure sufficient bond between the concrete and steel parts of the structure. The aim of this paper is to describe an experimental study on headed studs used in steel plate-concrete composite structures. Push-out tests were carried out to investigate the behaviour of shear connectors. The test specimens were prepared according to standard push-out tests, however, instead of I-beam, a steel plate 16 mm thick was used to better reflect the conditions in the real structure. The test specimens were produced in two batches using concrete with significantly different compressive strength. The experimental study was carried out on twelve specimens. Besides the traditional measurements based on LVDT sensors, optical measurements based on the digital image correlation method (DIC) and pattern tracking methods were used. DIC is a full-field contactless optical method for measuring displacements in experimental testing, based on the correlation of the digital images taken during test execution. With respect to conventional methods, optical measurements offer a wider scope of results and can give more information about the material or construction behaviour during the test. The ultimate load capacity and load-slip curves obtained from the experiments were compared with the values calculated based on Eurocodes, American and Chinese design specifications. It was observed that the use of the relationships developed for the traditional steel-concrete composite structures is justified in the case of ultimate load capacity of shear connectors in steel plate-concrete composite structures.

Preparation and Immunoaffinity Depletion of Fresh Frozen Tissue Homogenates for Mass Spectrometry-Based Proteomics in the Context of Drug Target/Biomarker Discovery.

PubMed

Prieto, DaRue A; Chan, King C; Johann, Donald J; Ye, Xiaoying; Whitely, Gordon; Blonder, Josip

2017-01-01

The discovery of novel drug targets and biomarkers via mass spectrometry (MS)-based proteomic analysis of clinical specimens has proven to be challenging. The wide dynamic range of protein concentration in clinical specimens and the high background/noise originating from highly abundant proteins in tissue homogenates and serum/plasma encompass two major analytical obstacles. Immunoaffinity depletion of highly abundant blood-derived proteins from serum/plasma is a well-established approach adopted by numerous researchers; however, the utilization of this technique for immunodepletion of tissue homogenates obtained from fresh frozen clinical specimens is lacking. We first developed immunoaffinity depletion of highly abundant blood-derived proteins from tissue homogenates, using renal cell carcinoma as a model disease, and followed this study by applying it to different tissue types. Tissue homogenate immunoaffinity depletion of highly abundant proteins may be equally important as is the recognized need for depletion of serum/plasma, enabling more sensitive MS-based discovery of novel drug targets, and/or clinical biomarkers from complex clinical samples. Provided is a detailed protocol designed to guide the researcher through the preparation and immunoaffinity depletion of fresh frozen tissue homogenates for two-dimensional liquid chromatography, tandem mass spectrometry (2D-LC-MS/MS)-based molecular profiling of tissue specimens in the context of drug target and/or biomarker discovery.

Evaluation of fracture toughness of human dentin using elastic-plastic fracture mechanics.

PubMed

Yan, Jiahau; Taskonak, Burak; Platt, Jeffrey A; Mecholsky, John J

2008-01-01

Dentin, the mineralized tissue forming the bulk of the tooth, lies between the enamel and the pulp chamber. It is a rich source of inspiration for designing novel synthetic materials due to its unique microstructure. Most of the previous studies investigating the fracture toughness of dentin have used linear-elastic fracture mechanics (LEFM) that ignores plastic deformation and could underestimate the toughness of dentin. With the presence of collagen (approximately 30% by volume) aiding the toughening mechanisms in dentin, we hypothesize that there is a significant difference between the fracture toughness estimated using LEFM (Kc) and elastic-plastic fracture mechanics (EPFM) (KJc). Single-edge notched beam specimens with in-plane (n=10) and anti-plane (n=10) parallel fractures were prepared following ASTM standard E1820 and tested in three-point flexure. KJc of the in-plane parallel and anti-plane parallel specimens were found to be 3.1 and 3.4 MPa m 1/2 and Kc were 2.4 and 2.5 MPa m 1/2, respectively. The fracture toughness estimated based on KJc is significantly greater than that estimated based on Kc (32.5% on average; p<0.001). In addition, KJc of anti-plane parallel specimens is significantly greater than that of in-plane parallel specimens. We suggest that, in order to critically evaluate the fracture toughness of human dentin, EPFM should be employed.

Cryptic species revealed by molecular phylogenetic analysis of sequences obtained from basidiomata of Tulasnella.

PubMed

Cruz, Darío; Suárez, Juan Pablo; Kottke, Ingrid; Piepenbring, Meike

2014-01-01

Delimitation of species and the search for a proper threshold for defining phylogenetic species in fungi are under discussion. In this study, morphological and molecular data are correlated to delimit species of Tulasnella, the most important mycobionts of Orchidaceae, which suffer from poor taxonomy. Resupinate basidiomata of Tulasnella species were collected in Ecuador and Germany, and 11 specimens (seven from Ecuador, four from Germany) were assigned to traditional species concepts by use of morphological keys. The specimens were compared by micro-anatomical examination with 75 specimens of Tulasnella borrowed from fungaria to obtain better insights on variation of characters. Sequences of the ITS region (127) were obtained after cloning from the fresh basidiomata and from pure cultures. Proportional variability of ITS sequences was analyzed within and among the cultures and the specimens designated to different morphospecies. Results suggested an intragenomic variation of less than 2%, an intraspecific variation of up to 4% and an interspecific divergence of more than 9% in Tulasnella. Cryptic species in Tulasnella, mostly from Ecuador, were revealed by phylogenetic analyses with 4% intraspecific divergence as a minimum threshold for delimiting species. Conventional diagnostic morphological characters appeared insufficient for species characterization. Arguments are presented for molecular delimitation of the established species Tulasnella albida, T. asymmetrica, T. eichleriana, T. cf. pinicola, T. tomaculum and T. violea. © 2014 by The Mycological Society of America.

Rheological Characteristics of Cement Grout and its Effect on Mechanical Properties of a Rock Fracture

NASA Astrophysics Data System (ADS)

Liu, Quansheng; Lei, Guangfeng; Peng, Xingxin; Lu, Chaobo; Wei, Lai

2018-02-01

Grouting reinforcement, which has an obvious strengthening effect on fractured rock mass, has been widely used in various fields in geotechnical engineering. The rheological properties of grout will greatly affect its diffusion radius in rock fractures, and the water-cement ratio is an important factor in determining the grouting flow patterns. The relationship between shear stress and shear rate which could reflect the grout rheological properties, the effects of water-cement ratio, and temperature on the rheological properties of grouting was studied in the laboratory. Besides, a new method for producing fractured rock specimens was proposed and solved the problem of producing natural fractured rock specimens. To investigate the influences of grouting on mechanical properties of a rock fracture, the fractured rock specimens made using the new method were reinforced by grouting on the independent designed grouting platform, and then normal and tangential mechanical tests were carried out on fractured rock specimens. The results showed that the mechanical properties of fractured rock mass are significantly improved by grouting, the peak shear strength and residual strength of rock fractures are greatly improved, and the resistance to deformation is enhanced after grouting. Normal forces affect the tangential behavior of the rock fracture, and the tangential stress strength increases with normal forces. The strength and stability of fractured rock mass are increased by grouting reinforcement.

Catalog of type specimens of recent mammals: Orders Carnivora, Perissodactyla, Artiodactyla, and Cetacea in the National Museum of Natural History, Smithsonian Institution

USGS Publications Warehouse

Fisher, Robert D.; Ludwig, Craig A.

2016-01-01

The type collection of Recent mammals in the Division of Mammals, National Museum of Natural History, Smithsonian Institution, contains 612 specimens bearing names of 604 species-group taxa of Carnivora, Perissodactyla, Artiodactyla, and Cetacea as of May 2016. This catalog presents an annotated list of these holdings comprising 582 holotypes; 16 lectotypes, two of which are newly designated herein; 7 syntypes (15 specimens); and 1 neotype. Included are several specimens that should be in the collection but cannot be found or are now known to be in other collections and therefore are not in the database. Thirty-seven of the names are new since the last type catalog covering these orders, Arthur J. Poole and Viola S. Schantz’s 1942 “Catalog of the Type Specimens of Mammals in the United States National Museum, Including the Biological Surveys Collection” (Bulletin of the United States National Museum, 178). One of these, Lutra iowa Goldman, 1941, was transferred to the National Museum’s Paleobiology Department collection and is mentioned only briefly in this work. Orders and families are arranged systematically following D. E. Wilson and D. M. Reeder’s 2005 Mammal Species of the World: A Taxonomic and Geographic Reference, third edition, volume 1; within families, currently recognized genera are arranged alphabetically, and within each currently recognized genus, species and subspecies accounts are arranged alphabetically by original published name. Information in each account includes original name and abbreviated citation thereto, current name if other than original, citation for first use of current name combination for the taxon, type designation, U.S. National Museum catalog number(s), preparation, age and sex, date of collection and collector, original collector number, type locality, and remarks as appropriate. Digital photographs of each specimen will serve as a condition report and will be attached to each electronic specimen record. An addendum contains two accounts for holotypes added to the collection subsequent to the publication of the catalog for their taxa. Appendices tabulate summary data for all four of our recent type catalogs (Fisher and Ludwig, 2012, 2014, 2015, and this volume) and include authors of names, collectors of type specimens, countries, islands, and provinces or states in which type specimens were collected, numbers of new names per decade, and summary numbers for holotypes, lectotypes, syntypes, neotypes, and new taxa since the last type catalog (Poole and Schantz, 1942) covering the entire type collection.

Development of a fiber optic pavement subgrade strain measurement system

NASA Astrophysics Data System (ADS)

Miller, Craig Emerson

2000-11-01

This dissertation describes the development of a fiber optic sensing system to measure strains within the soil subgrade of highway pavements resulting from traffic loads. The motivation to develop such a device include improvements to: (1)all phases of pavement design, (2)theoretical models used to predict pavement performance, and (3)pavement rehabilitation. The design of the sensing system encompasses selecting an appropriate transducer design as well as the development of optimal optical and demodulation systems. The first is spring based, which attempts to match its spring stiffness to that of the soil-data indicate it is not an optimal transducer design. The second transducer implements anchoring plates attached to two telescoping tubes which allows the soil to be compacted to a desired density between the plates to dictate the transducer's behavior. Both transducers include an extrinsic Fabry- Perot cavity to impose the soil strains onto a phase change of the optical signal propagating through the cavity. The optical system includes a low coherence source and allows phase modulation via path length stretching by adding a second interferometer in series with the transducer, resulting in a path matched differential interferometer. A digitally implemented synthetic heterodyne demodulator based on a four step phase stepping algorithm is used to obtain unambiguous soil strain information from the displacement of the Fabry-Perot cavity. The demodulator is calibrated and characterized by illuminating the transducer with a second long coherence source of different wavelength. The transducer using anchoring plates is embedded within cylindrical soil specimens of varying soil types and soil moisture contents. Loads are applied to the specimen and resulting strains are measured using the embedded fiber optic gage and LVDTs attached to the surface of the specimen. This experimental verification is substantiated using a finite element analysis to predict any differences between interior and surface strains in the specimens. The experimental data indicate 2-inch diameter anchoring plates embedded in soil close to its optimum moisture content allow for very accurate soil strain measurements.

In Situ TEM Study of Interaction between Dislocations and a Single Nanotwin under Nanoindentation.

PubMed

Wang, Bo; Zhang, Zhenyu; Cui, Junfeng; Jiang, Nan; Lyu, Jilei; Chen, Guoxin; Wang, Jia; Liu, Zhiduo; Yu, Jinhong; Lin, Chengte; Ye, Fei; Guo, Dongming

2017-09-06

Nanotwinned (nt) materials exhibit excellent mechanical properties, and have been attracting much more attention of late. Nevertheless, the fundamental mechanism of interaction between dislocations and a single nanotwin is not understood. In this study, in situ transmission electron microscopy (TEM) nanoindentation is performed, on a specimen of a nickel (Ni) alloy containing a single nanotwin of 89 nm in thickness. The specimen is prepared using focused ion beam (FIB) technique from an nt surface, which is formed by a novel approach under indentation using a developed diamond panel with tips array. The stiffness of the specimen is ten times that of the pristine counterparts during loading. The ultrahigh stiffness is attributed to the generation of nanotwins and the impediment of the single twin to the dislocations. Two peak loads are induced by the activation of a new slip system and the penetration of dislocations over the single nanotwin, respectively. One slip band is parallel to the single nanotwin, indicating the slip of dislocations along the nanotwin. In situ TEM observation of nanoindentation reveals a new insight for the interaction between dislocations and a single nanotwin. This paves the way for design and preparation of high-performance nt surfaces of Ni alloys used for aircraft engines, gas turbines, turbocharger components, ducts, and absorbers.

A novel multimodal optical imaging system for early detection of oral cancer

PubMed Central

Malik, Bilal H.; Jabbour, Joey M.; Cheng, Shuna; Cuenca, Rodrigo; Cheng, Yi-Shing Lisa; Wright, John M.; Jo, Javier A.; Maitland, Kristen C.

2015-01-01

Objectives Several imaging techniques have been advocated as clinical adjuncts to improve identification of suspicious oral lesions. However, these have not yet shown superior sensitivity or specificity over conventional oral examination techniques. We developed a multimodal, multi-scale optical imaging system that combines macroscopic biochemical imaging of fluorescence lifetime imaging (FLIM) with subcellular morphologic imaging of reflectance confocal microscopy (RCM) for early detection of oral cancer. We tested our system on excised human oral tissues. Study Design A total of four tissue specimen were imaged. These specimens were diagnosed as one each: clinically normal, oral lichen planus, gingival hyperplasia, and superficially-invasive squamous cell carcinoma (SCC). The optical and fluorescence lifetime properties of each specimen were recorded. Results Both quantitative and qualitative differences between normal, benign and SCC lesions can be resolved with FLIM-RCM imaging. The results demonstrate that an integrated approach based on these two methods can potentially enable rapid screening and evaluation of large areas of oral epithelial tissue. Conclusions Early results from ongoing studies of imaging human oral cavity illustrate the synergistic combination of the two modalities. An adjunct device based on such optical characterization of oral mucosa can potentially be used to detect oral carcinogenesis in early stages. PMID:26725720

Coherent Raman Scattering Microscopy for Evaluation of Head and Neck Carcinoma.

PubMed

Hoesli, Rebecca C; Orringer, Daniel A; McHugh, Jonathan B; Spector, Matthew E

2017-09-01

Objective We aim to describe a novel, label-free, real-time imaging technique, coherent Raman scattering (CRS) microscopy, for histopathological evaluation of head and neck cancer. We evaluated the ability of CRS microscopy to delineate between tumor and nonneoplastic tissue in tissue samples from patients with head and neck cancer. Study Design Prospective case series. Setting Tertiary care medical center. Subjects and Methods Patients eligible were surgical candidates with biopsy-proven, previously untreated head and neck carcinoma and were consented preoperatively for participation in this study. Tissue was collected from 50 patients, and after confirmation of tumor and normal specimens by hematoxylin and eosin (H&E), there were 42 tumor samples and 42 normal adjacent controls. Results There were 42 confirmed carcinoma specimens on H&E, and CRS microscopy identified 37 as carcinoma. Of the 42 normal specimens, CRS microscopy identified 40 as normal. This resulted in a sensitivity of 88.1% and specificity of 95.2% in distinguishing between neoplastic and nonneoplastic images. Conclusion CRS microscopy is a unique label-free imaging technique that can provide rapid, high-resolution images and can accurately determine the presence of head and neck carcinoma. This holds potential for implementation into standard practice, allowing frozen margin evaluation even at institutions without a histopathology laboratory.

Effect of beverages on bovine dental enamel subjected to erosive challenge with hydrochloric acid.

PubMed

Amoras, Dinah Ribeiro; Corona, Silmara Aparecida Milori; Rodrigues, Antonio Luiz; Serra, Mônica Campos

2012-01-01

This study evaluated by an in vitro model the effect of beverages on dental enamel previously subjected to erosive challenge with hydrochloric acid. The factor under study was the type of beverage, in five levels: Sprite® Zero Low-calorie Soda Lime (positive control), Parmalat® ultra high temperature (UHT) milk, Ades® Original soymilk, Leão® Ice Tea Zero ready-to-drink low-calorie peach-flavored black teaand Prata® natural mineral water (negative control). Seventy-five bovine enamel specimens were distributed among the five types of beverages (n=15), according to a randomized complete block design. For the formation of erosive wear lesions, the specimens were immersed in 10 mL aqueous solution of hydrochloric acid 0.01 M for 2 min. Subsequently, the specimens were immersed in 20 mL of the beverages for 1 min, twice daily for 2 days at room temperature. In between, the specimens were kept in 20 mL of artificial saliva at 37ºC. The response variable was the quantitative enamel microhardness. ANOVA and Tukey's test showed highly significant differences (p<0.00001) in the enamel exposed to hydrochloric acid and beverages. The soft drink caused a significantly higher decrease in microhardness compared with the other beverages. The black tea caused a significantly higher reduction in microhardness than the mineral water, UHT milk and soymilk, but lower than the soft drink. Among the analyzed beverages, the soft drink and the black tea caused the most deleterious effects on dental enamel microhardness.

Specimen-specific modeling of hip fracture pattern and repair.

PubMed

Ali, Azhar A; Cristofolini, Luca; Schileo, Enrico; Hu, Haixiang; Taddei, Fulvia; Kim, Raymond H; Rullkoetter, Paul J; Laz, Peter J

2014-01-22

Hip fracture remains a major health problem for the elderly. Clinical studies have assessed fracture risk based on bone quality in the aging population and cadaveric testing has quantified bone strength and fracture loads. Prior modeling has primarily focused on quantifying the strain distribution in bone as an indicator of fracture risk. Recent advances in the extended finite element method (XFEM) enable prediction of the initiation and propagation of cracks without requiring a priori knowledge of the crack path. Accordingly, the objectives of this study were to predict femoral fracture in specimen-specific models using the XFEM approach, to perform one-to-one comparisons of predicted and in vitro fracture patterns, and to develop a framework to assess the mechanics and load transfer in the fractured femur when it is repaired with an osteosynthesis implant. Five specimen-specific femur models were developed from in vitro experiments under a simulated stance loading condition. Predicted fracture patterns closely matched the in vitro patterns; however, predictions of fracture load differed by approximately 50% due to sensitivity to local material properties. Specimen-specific intertrochanteric fractures were induced by subjecting the femur models to a sideways fall and repaired with a contemporary implant. Under a post-surgical stance loading, model-predicted load sharing between the implant and bone across the fracture surface varied from 59%:41% to 89%:11%, underscoring the importance of considering anatomic and fracture variability in the evaluation of implants. XFEM modeling shows potential as a macro-level analysis enabling fracture investigations of clinical cohorts, including at-risk groups, and the design of robust implants. © 2013 Published by Elsevier Ltd.

Sex-Based Differences of Medial Collateral Ligament and Anterior Cruciate Ligament Strains With Cadaveric Impact Simulations.

PubMed

Schilaty, Nathan D; Bates, Nathaniel A; Nagelli, Christopher V; Krych, Aaron J; Hewett, Timothy E

2018-04-01

Female patients sustain noncontact knee ligament injuries at a greater rate compared with their male counterparts. The cause of these differences in the injury rate and the movements that load the ligaments until failure are still under dispute in the literature. This study was designed to determine differences in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strains between male and female cadaveric specimens during a simulated athletic task. The primary hypothesis tested was that female limbs would demonstrate significantly greater ACL strain compared with male limbs under similar loading conditions. A secondary hypothesis was that MCL strain would not differ between sexes. Controlled laboratory study. Motion analysis of 67 athletes performing a drop vertical jump was conducted. Kinetic data were used to categorize injury risk according to tertiles, and these values were input into a cadaveric impact simulator to assess ligamentous strain during a simulated landing task. Uniaxial and multiaxial load cells and differential variable reluctance transducer strain sensors were utilized to collect mechanical data for analysis. Conditions of external loads applied to the cadaveric limbs (knee abduction moment, anterior tibial shear, and internal tibial rotation) were varied and randomized. Data were analyzed using 1-way analysis of variance (ANOVA), 2-way repeated-measures ANOVA, and the Fisher exact test. There were no significant differences ( P = .184) in maximum ACL strain between male (13.2% ± 8.1%) and female (16.7% ± 8.3%) specimens. Two-way ANOVA demonstrated that across all controlled external load conditions, female specimens consistently attained at least 3.5% increased maximum ACL strain compared with male specimens ( F 1,100 = 4.188, P = .043); however, when normalized to initial contact, no significant difference was found. There were no significant differences in MCL strain between sexes for similar parameters. When compared with baseline, female specimens exhibited greater values of ACL strain at maximum, initial contact, and after impact (33, 66, and 100 milliseconds, respectively) than male specimens during similar loading conditions, with a maximum strain difference of at least 3.5%. During these same loading conditions, there were no differences in MCL loading between sexes, and only a minimal increase of MCL loading occurred during the impact forces. Our results indicate that female patients are at an increased risk for ACL strain across all similar conditions compared with male patients. These data demonstrate that female specimens, when loaded similarly to male specimens, experience additional strain on the ACL. As the mechanical environment was similar for both sexes with these simulations, the greater ACL strain of female specimens must be attributed to ligament biology, anatomic differences, or muscular stiffness.

24 CFR 3280.405 - Standard for swinging exterior passage doors for use in manufactured homes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging Exterior... requirements. The design and construction of exterior door units must meet all requirements of AAMA 1702.2-95.... For homes designed to be located in Wind Zones II and III, manufacturers shall design exterior walls...

24 CFR 3280.405 - Standard for swinging exterior passage doors for use in manufactured homes.

Code of Federal Regulations, 2013 CFR

2013-04-01

... pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging Exterior... requirements. The design and construction of exterior door units must meet all requirements of AAMA 1702.2-95.... For homes designed to be located in Wind Zones II and III, manufacturers shall design exterior walls...

24 CFR 3280.405 - Standard for swinging exterior passage doors for use in manufactured homes.

Code of Federal Regulations, 2011 CFR

2011-04-01

... pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging Exterior... requirements. The design and construction of exterior door units must meet all requirements of AAMA 1702.2-95.... For homes designed to be located in Wind Zones II and III, manufacturers shall design exterior walls...

24 CFR 3280.405 - Standard for swinging exterior passage doors for use in manufactured homes.

Code of Federal Regulations, 2012 CFR

2012-04-01

... pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging Exterior... requirements. The design and construction of exterior door units must meet all requirements of AAMA 1702.2-95.... For homes designed to be located in Wind Zones II and III, manufacturers shall design exterior walls...

24 CFR 3280.405 - Standard for swinging exterior passage doors for use in manufactured homes.

Code of Federal Regulations, 2014 CFR

2014-04-01

... pre-production specimen test in accordance with AAMA 1702.2-95, Voluntary Standard Swinging Exterior... requirements. The design and construction of exterior door units must meet all requirements of AAMA 1702.2-95.... For homes designed to be located in Wind Zones II and III, manufacturers shall design exterior walls...

Impact of Gastric Acid Induced Surface Changes on Mechanical Behavior and Optical Characteristics of Dental Ceramics.

PubMed

Kulkarni, Aditi; Rothrock, James; Thompson, Jeffery

2018-01-14

To test the impact of exposure to artificial gastric acid combined with toothbrush abrasion on the properties of dental ceramics. Earlier research has indicated that immersion in artificial gastric acid has caused increased surface roughness of dental ceramics; however, the combined effects of acid immersion and toothbrush abrasion and the impact of increased surface roughness on mechanical strength and optical properties have not been studied. Three commercially available ceramics were chosen for this study: feldspathic porcelain, lithium disilicate glass-ceramic, and monolithic zirconium oxide. The specimens (10 × 1 mm discs) were cut, thermally treated as required, and polished. Each material was divided into four groups (n = 8 per group): control (no exposure), acid only, brush only, acid + brush. The specimens were immersed in artificial gastric acid (50 ml of 0.2% [w/v] sodium chloride in 0.7% [v/v] hydrochloric acid mixed with 0.16 g of pepsin powder, pH = 2) for 2 minutes and rinsed with deionized water for 2 minutes. The procedure was repeated 6 times/day × 9 days, and specimens were stored in deionized water at 37°C. Toothbrush abrasion was performed using an ISO/ADA design brushing machine for 100 cycles/day × 9 days. The acid + brush group received both treatments. Specimens were examined under SEM and an optical microscope for morphological changes. Color and translucency were measured using spectrophotometer CIELAB coordinates (L*, a*, b*). Surface gloss was measured using a gloss meter. Surface roughness was measured using a stylus profilometer. Biaxial flexural strength was measured using a mechanical testing machine. The data were analyzed by one-way ANOVA followed by Tukey's HSD post hoc test (p < 0.05). Statistically significant changes were found for color, gloss, and surface roughness for porcelain and e.max specimens. No statistically significant changes were found for any properties of zirconia specimens. The acid treatment affected the surface roughness, color, and gloss of porcelain and e.max ceramics. The changes in translucency and mechanical strength for all materials were not statistically significant. Zirconia ceramic showed resistance to all treatments. © 2018 by the American College of Prosthodontists.

Dynamic Loading of Carrara Marble in a Heated State

NASA Astrophysics Data System (ADS)

Wong, Louis Ngai Yuen; Li, Zhihuan; Kang, Hyeong Min; Teh, Cee Ing

2017-06-01

Useable land is a finite space, and with a growing global population, countries have been exploring the use of underground space as a strategic resource to sustain the growth of their society and economy. However, the effects of impact loading on rocks that have been heated, and hence the integrity of the underground structure, are still not fully understood and has not been included in current design standards. Such scenarios include traffic accidents and explosions during an underground fire. This study aims to provide a better understanding of the dynamic load capacity of Carrara marble at elevated temperatures. Dynamic uniaxial compression tests are performed on Carrara marble held at various temperatures using a split-Hopkinson Pressure Bar (SHPB) setup with varying input force. A customized oven is included in the SHPB setup to allow for testing of the marble specimens in a heated state. After the loading test, a three-wave analysis is performed to obtain the dynamic stress-strain curve of the specimen under loading. The fragments of the failed specimens were also collected and dry-sieved to obtain the particle size distribution. The results reveal that the peak stress of specimens that have been heated is negatively correlated with the heating temperature. However, the energy absorbed by the specimens at peak stress at all temperatures is similar, indicating that a significant amount of energy is dissipated via plastic deformation. Generally, fragment size is also found to show a negative correlation with heating temperature and loading pressure. However, in some cases this relationship does not hold true, probably due to the occurrence of stress shadowing. Linear Elastic Fracture Mechanics has been found to be generally applicable to specimens tested at low temperatures; but at higher temperatures, Elastic-Plastic Fracture Mechanics will give a more accurate prediction. Another contribution of this study is to show that other than the peak stress of the rock failure type, the strain history experienced by the rock during impact and the post-impact fragment size distribution are also significant distinguishing features of damage caused by dynamic loading on heated rocks.

One-Piece Force-Transducer Body

NASA Technical Reports Server (NTRS)

Meyer, R. A.

1986-01-01

Rugged unit designed to operate in severe environment. Forcetransducer body designed for measurement of loads on specimens tested in hydrogen gas at temperatures up to 2,000 degree F (1,090 degree C). Body has symmetrical radial-shear-beam configuration and machined in one piece from bar stock.

Cinemicrographic specimen housing

NASA Technical Reports Server (NTRS)

Wilkins, J. R.

1979-01-01

Housing used to observe gravitation effects on specimens embedded in support media, such as agar, supports microbial specimens vertically for time-lapsed cinemicrographic studies. Procedure cannot be performed with conventional microscopes which see specimens in horizontal plane only.

Comparison of blood specimens from plain and gel vacuum blood collection tubes.

PubMed

Wiwanitkit, V

2001-05-01

This study was set in the Division of Laboratory Medicine, Chulalongkorn Hospital. All 2,000 blood specimens were randomly collected using evacuated blood collection by plain or gel vacuum tubes. After collection, each specimen was considered and judged using criteria of specimen rejection to determine how proper the specimen presentations were. All data were reviewed, collected and interpreted. It revealed that there were only 20 (1%) improper specimens and all were improper in quality. There was no significant difference between the ratio of improper specimens in both groups (P > 0.30). From this study, it revealed that efficacy of both types of vacuum tubes was not different. The new gel vacuum tube seems to be an effective tool in the evacuated blood collection system due to its advantage in reduction of time in specimen processing.

Effect of specific surface area of MWCNTS on surface roughness and delamination in drilling Epoxy/Glass Fabric Composite

NASA Astrophysics Data System (ADS)

Ponnuvel, S.; Ananth, M. Prem

2018-03-01

In this study the effect of specific surface area of the MWCNTs on the drilled hole qualities was investigated. Epoxy araldite LY556 with hardener HY951 and E-glass coarse plain weave fabric are used for the fabrication of reference material (specimen A). Multi-WalledCarbon Nanotubes (MWCNTs) with diameters <8 nm and 20–30 nm are used for the fabrication of study materials, namely specimen B and specimen C respectively. In specimen B the epoxy resin was filled with MWCNTs having a specific surface area >500 m2 g‑1. MWCNTs in specimen C had a specific surface area >110 m2 g‑1. Drilling experiments were conducted on all the three specimens. Two dimensional delamination factor and the surface roughness of the inner wall of the drilled holes were investigated using Grey Relational Analysis (GRA) and Analysis of variance (ANOVA). Two dimensional delamination factor showed better performance from specimen B and specimen C in comparison with specimen A suggesting improvement in the bonding between epoxy and the glass fiber in the presence of MWCNTs. Similar observations were made for surface roughness of the inner wall of the drilled holes at 1250 rpm. Whereas the presence of MWCNTs (Specimen B and specimen C) produced poor surface finish at 500 rpm in comparison with specimen A. Variations in the hole quality characteristics between specimen B and specimen C was marginal with better observations in specimen C.

The terminal crest: morphological features relevant to electrophysiology

PubMed Central

Sánchez-Quintana, D; Anderson, R H; Cabrera, J A; Climent, V; Martin, R; Farré, J; Ho, S Y

2002-01-01

Objective: To investigate the detailed anatomy of the terminal crest (crista terminalis) and its junctional regions with the pectinate muscles and intercaval area to provide the yardstick for structural normality. Design: 97 human necropsy hearts were studied from patients who were not known to have medical histories of atrial arrhythmias. The dimensions of the terminal crest were measured in width and thickness from epicardium to endocardium, at the four points known to be chosen as sites of ablation. Results: The pectinate muscles originating from the crest and extending along the wall of the appendage towards the vestibule of the tricuspid valve had a non-uniform trabecular pattern in 80% of hearts. Fine structure of the terminal crest studied using light and scanning electron microscopy consisted of much thicker and more numerous fibrous sheaths of endomysium with increasing age of the patient. 36 specimens of 45 (80%) specimens studied by electron microscopy had a predominantly uniform longitudinal arrangement of myocardial fibres within the terminal crest. In contrast, in all specimens, the junctional areas of the terminal crest with the pectinate muscles and with the intercaval area had crossing and non-uniform architecture of myofibres. Conclusions: The normal anatomy of the muscle fibres and connective tissue in the junctional area of the terminal crest/pectinate muscles and terminal crest/intercaval bundle favours non-uniform anisotropic properties. PMID:12231604

Improving the transport of urgent specimens to an off-site laboratory using a novel sticker-tracker.

PubMed

Sepahzad, Afsoon; Ejiofor, Florence; Giles, Susan; Klaber, Robert

2013-01-01

Obtaining results for urgent microbiology specimens in an efficient manner is imperative to ensure that patients receive appropriate antibiotic therapy. A previous audit carried out in the Paediatric department of a central teaching hospital and a number of clinical incidents, highlighted a delay in transport of specimens (exceeding eight hours) and 'missing' specimens. This results in empirical antibiotic treatment of infection, with delay in confirming microbiology result and unnecessary, distressing repeat investigation. As an initial step we sought staff opinion to further explore the problem. A sticker was designed for the microbiology specimen bag to assign accountability, track each step in the transport process and to raise awareness of the problem. The sticker required the member of staff responsible at each stage of the process to time, date and sign it, to allow tracking of potential delays. The new sticker tracking system was promoted and launched in the Paediatric department. Initial challenges included lack of awareness of the protocol and lack of pods for sending urgent specimens. The team met regularly and completed stickers were analysed weekly to identify on-going issues and to devise solutions. Consequently total transport time was reduced to an average of 69 minutes by September (within four hr target). Our intervention improved the efficiency and reliability of urgent specimen transport. This is likely to result in safer antibiotic use and avoid the need for repeat investigation. The system is now also used in the Neonatal department and has lead to the development of a new 'Central Specimens Reception'.

Computer vision applied to herbarium specimens of German trees: testing the future utility of the millions of herbarium specimen images for automated identification.

PubMed

Unger, Jakob; Merhof, Dorit; Renner, Susanne

2016-11-16

Global Plants, a collaborative between JSTOR and some 300 herbaria, now contains about 2.48 million high-resolution images of plant specimens, a number that continues to grow, and collections that are digitizing their specimens at high resolution are allocating considerable recourses to the maintenance of computer hardware (e.g., servers) and to acquiring digital storage space. We here apply machine learning, specifically the training of a Support-Vector-Machine, to classify specimen images into categories, ideally at the species level, using the 26 most common tree species in Germany as a test case. We designed an analysis pipeline and classification system consisting of segmentation, normalization, feature extraction, and classification steps and evaluated the system in two test sets, one with 26 species, the other with 17, in each case using 10 images per species of plants collected between 1820 and 1995, which simulates the empirical situation that most named species are represented in herbaria and databases, such as JSTOR, by few specimens. We achieved 73.21% accuracy of species assignments in the larger test set, and 84.88% in the smaller test set. The results of this first application of a computer vision algorithm trained on images of herbarium specimens shows that despite the problem of overlapping leaves, leaf-architectural features can be used to categorize specimens to species with good accuracy. Computer vision is poised to play a significant role in future rapid identification at least for frequently collected genera or species in the European flora.

Cochlear implant-related three-dimensional characteristics determined by micro-computed tomography reconstruction.

PubMed

Ni, Yusu; Dai, Peidong; Dai, Chunfu; Li, Huawei

2017-01-01

To explore the structural characteristics of the cochlea in three-dimensional (3D) detail using 3D micro-computed tomography (mCT) image reconstruction of the osseous labyrinth, with the aim of improving the structural design of electrodes, the selection of stimulation sites, and the effectiveness of cochlear implantation. Three temporal bones were selected from among adult donors' temporal bone specimens. A micro-CT apparatus (GE eXplore) was used to scan three specimens with a voxel resolution of 45 μm. We obtained about 460 slices/specimen, which produced abundant data. The osseous labyrinth images of three specimens were reconstructed from mCT. The cochlea and its spiral characteristics were measured precisely using Able Software 3D-DOCTOR. The 3D images of the osseous labyrinth, including the cochlea, vestibule, and semicircular canals, were reconstructed. The 3D models of the cochlea showed the spatial relationships and surface structural characteristics. Quantitative data concerning the cochlea and its spiral structural characteristics were analyzed with regard to cochlear implantation. The 3D reconstruction of mCT images clearly displayed the detailed spiral structural characteristics of the osseous labyrinth. Quantitative data regarding the cochlea and its spiral structural characteristics could help to improve electrode structural design, signal processing, and the effectiveness of cochlear implantation. Clin. Anat. 30:39-43, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

High-Performance Liquid Chromatography with Tandem Mass Spectrometry for the Determination of Nine Hallucinogenic 25-NBOMe Designer Drugs in Urine Specimens

PubMed Central

Poklis, Justin L.; Clay, Deborah J.; Poklis, Alphonse

2014-01-01

We present a high-performance liquid chromatography triple quadrupole mass spectrometry (HPLC–MS-MS) method for the identification and quantification of nine serotonin 5-HT2A receptor agonist hallucinogenic substances from a new class of N-methoxybenzyl derivatives of methoxyphenylethylamine (NBOMe) designer drugs in human urine: 25H-NBOMe, 2CC-NBOMe, 25I-NBF, 25D-NBOMe, 25B-NBOMe, 2CT-NBOMe, 25I-NBMD, 25G-NBOMe and 25I-NBOMe. This assay was developed for the Virginia Commonwealth University Clinical and Forensic Toxicology laboratory to screen emergency department specimens in response to an outbreak of N-benzyl-phenethylamine derivative abuse and overdose cases in Virginia. The NBOMe derivatives were rapidly extracted from the urine specimens by use of FASt™ solid-phase extraction columns. Assay performance was determined as recommended for validation by the Scientific Working Group for Forensic Toxicology (SWGTOX) for linearity, lower limit of quantification, lower limit of detection, accuracy/bias, precision, dilution integrity, carryover, selectivity, absolute recovery, ion suppression and stability. Linearity was verified to be from 1 to 100 ng/mL for each of the nine analytes. The bias determined for the NBOMe derivatives was 86–116% with a <14% coefficient of variation over the linear range of the assay. Four different NBOMe derivatives were detected using the presented method in patient urine specimens. PMID:24535338

Low Activation Joining of SiC/SiC Composites for Fusion Applications: Modeling Miniature Torsion Tests

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

Henager, Charles H.; Nguyen, Ba Nghiep; Kurtz, Richard J.

2014-06-30

The use of SiC and SiC-composites in fission or fusion environments appears to require joining methods for assembling systems. The international fusion community has designed miniature torsion specimens for joint testing and for irradiation in HFIR. Therefore, miniature torsion joints were fabricated using displacement reactions between Si and TiC to produce Ti3SiC2 + SiC joints with CVD-SiC that were tested in shear prior to and after HFIR irradiation. However, these torsion specimens fail out-of-plane, which causes difficulties in determining a shear strength for the joints or for comparing unirradiated and irradiated joints. A finite element damage model has been developedmore » that indicates fracture is likely to occur within the joined pieces to cause out-of-plane failures for miniature torsion specimens when a certain modulus and strength ratio between the joint material and the joined material exists. The implications for torsion shear joint data based on this sample design are discussed.« less

An Investigation into the Postbuckling Response of a Single Blade-Stiffened Composite Panel

NASA Astrophysics Data System (ADS)

Spediacci, Alexander Daniel

The large strength reserves of stiffened composite structures in the postbuckling range appeal to the aerospace industry because of the high strength-to weight-ratio. Design and analysis of these large-scale, complex structures is technical, and requires major computational effort. Using the building-block approach, a smaller, single-stringer panel can be a useful and efficient tool for initial design, and can reveal critical behavior of a larger, multi-stringer panel. A characterization, through finite element modeling, of buckling and postbuckling response of a single blade-stiffened composite panel is proposed. Several factors affecting buckling and postbuckling behavior are investigated, including specimen length, initial imperfections, mode switching, and skin stringer separation. Two specimens are repeatedly tested under quasi- static compression loading well into the postbuckling range, showing no sign of damage. The test data from the specimens are used to compare and validate the nonlinear finite element models, show good correlation with the models. Ultimately, this work will serve to demonstrate the safety of stiffened structures operating in the postbuckling range and allow for thinner, lighter structures, which can increase the overall efficiency of aircraft.

High pressure reaction cell and transfer mechanism for ultrahigh vacuum spectroscopic chambers

NASA Astrophysics Data System (ADS)

Nelson, A. E.; Schulz, K. H.

2000-06-01

A novel high pressure reaction cell and sample transfer mechanism for ultrahigh vacuum (UHV) spectroscopic chambers is described. The design employs a unique modification of a commercial load-lock transfer system to emulate a tractable microreactor. The reaction cell has an operating pressure range of <1×10-4 to 1000 Torr and can be evacuated to UHV conditions to enable sample transfer into the spectroscopic chamber. Additionally, a newly designed sample holder equipped with electrical and thermocouple contacts is described. The sample holder is capable of resistive specimen heating to 400 and 800 °C with current requirements of 14 A (2 V) and 25 A (3.5 V), respectively. The design enables thorough material science characterization of catalytic reactions and the surface chemistry of catalytic materials without exposing the specimen to atmospheric contaminants. The system is constructed primarily from readily available commercial equipment allowing its rapid implementation into existing laboratories.

Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements

NASA Technical Reports Server (NTRS)

Rey, Charles A.

1991-01-01

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

Development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements

NASA Astrophysics Data System (ADS)

Rey, Charles A.

1991-03-01

The development of high temperature containerless processing equipment and the design and evaluation of associated systems required for microgravity materials processing and property measurements are discussed. Efforts were directed towards the following task areas: design and development of a High Temperature Acoustic Levitator (HAL) for containerless processing and property measurements at high temperatures; testing of the HAL module to establish this technology for use as a positioning device for microgravity uses; construction and evaluation of a brassboard hot wall Acoustic Levitation Furnace; construction and evaluation of a noncontact temperature measurement (NCTM) system based on AGEMA thermal imaging camera; construction of a prototype Division of Amplitude Polarimetric Pyrometer for NCTM of levitated specimens; evaluation of and recommendations for techniques to control contamination in containerless materials processing chambers; and evaluation of techniques for heating specimens to high temperatures for containerless materials experimentation.

Impact resistant boron/aluminum composites for large fan blades

NASA Technical Reports Server (NTRS)

Oller, T. L.; Salemme, C. T.; Bowden, J. H.; Doble, G. S.; Melnyk, P.

1977-01-01

Blade-like specimens were subjected to static ballistic impact testing to determine their relative FOD impact resistance levels. It was determined that a plus or minus 15 deg layup exhibited good impact resistance. The design of a large solid boron/aluminum fan blade was conducted based on the FOD test results. The CF6 fan blade was used as a baseline for these design studies. The solid boron/aluminum fan blade design was used to fabricate two blades. This effort enabled the assessment of the scale up of existing blade manufacturing details for the fabrication of a large B/Al fan blade. Existing CF6 fan blade tooling was modified for use in fabricating these blades.

Growth and characterization of benzaldehyde 4-nitro phenyl hydrazone (BPH) single crystal: A proficient second order nonlinear optical material

NASA Astrophysics Data System (ADS)

Saravanan, M.; Abraham Rajasekar, S.

2016-04-01

The crystals (benzaldehyde 4-nitro phenyl hydrazone (BPH)) appropriate for NLO appliance were grown by the slow cooling method. The solubility and metastable zone width measurement of BPH specimen was studied. The material crystallizes in the monoclinic crystal system with noncentrosymmetric space group of Cc. The optical precision in the whole visible region was found to be excellent for non-linear optical claim. Excellence of the grown crystal is ascertained by the HRXRD and etching studies. Laser Damage Threshold and Photoluminescence studies designate that the grown crystal contains less imperfection. The mechanical behaviour of BPH sample at different temperatures was investigated to determine the hardness stability of the grown specimen. The piezoelectric temperament and the relative Second Harmonic Generation (for diverse particle sizes) of the material were also studied. The dielectric studies were executed at varied temperatures and frequencies to investigate the electrical properties. Photoconductivity measurement enumerates consummate of inducing dipoles due to strong incident radiation and also divulge the nonlinear behaviour of the material. The third order nonlinear optical properties of BPH crystals were deliberate by Z-scan method.

Using biological and physico-chemical test methods to assess the role of concrete mixture design in resistance to microbially induced corrosion

NASA Astrophysics Data System (ADS)

House, Mitchell Wayne

Concrete is the most widely used material for construction of wastewater collection, storage, and treatment infrastructure. The chemical and physical characteristics of hydrated portland cement make it susceptible to degradation under highly acidic conditions. As a result, some concrete wastewater infrastructure may be susceptible to a multi-stage degradation process known as microbially induced corrosion, or MIC. MIC begins with the production of aqueous hydrogen sulfide (H2S(aq)) by anaerobic sulfate reducing bacteria present below the waterline. H2S(aq) partitions to the gas phase where it is oxidized to sulfuric acid by the aerobic sulfur oxidizing bacteria Thiobacillus that resides on concrete surfaces above the waterline. Sulfuric acid then attacks the cement paste portion of the concrete matrix through decalcification of calcium hydroxide and calcium silica hydrate coupled with the formation of expansive corrosion products. The attack proceeds inward resulting in reduced service life and potential failure of the concrete structure. There are several challenges associated with assessing a concrete's susceptibility to MIC. First, no standard laboratory tests exist to assess concrete resistance to MIC. Straightforward reproduction of MIC in the laboratory is complicated by the use of microorganisms and hydrogen sulfide gas. Physico-chemical tests simulating MIC by immersing concrete specimens in sulfuric acid offer a convenient alternative, but do not accurately capture the damage mechanisms associated with biological corrosion. Comparison of results between research studies is difficult due to discrepancies that can arise in experimental methods even if current ASTM standards are followed. This thesis presents two experimental methods to evaluate concrete resistance to MIC: one biological and one physico-chemical. Efforts are made to address the critical aspects of each testing method currently absent in the literature. The first method presented is a new test to evaluate performance of concrete specimens under conditions designed to accelerate MIC. Concrete specimens representing 12 mixture designs were inoculated with 5 species of Thiobacillus bacteria and placed in a biological growth chamber designed to encourage bacterial growth and sulfuric acid production by optimizing temperature, delivering necessary nutrients, and providing hydrogen sulfide gas. Results indicate that using supplementary cementitious materials, limestone aggregates, and sulfate resistant cement can improve resistance to MIC. It is interesting to note that this study showed that unlike many other durability problems the role of water to cement ratio was unclear. The second method presented is a sulfuric acid immersion study designed to evaluate the resistance of 12 concrete mixture designs to 5 concentrations of sulfuric acid. Experimental protocols (like those in ASTM) previously considered trivial were found to have a dramatic effect on experimental results. It was found that using supplementary cementitious materials, limestone coarse aggregate, and sulfate resistant cement can increase concrete resistance to moderate sulfuric acid concentrations. The primary damage mechanism was observed to change depending on sulfuric acid concentration. Rapid deterioration of specimens exposed to aggressive sulfuric acid solutions indicates that degradation of concrete under the most severe MIC conditions (i.e., a pH < 1.0) cannot be prevented by strictly manipulating concrete mixture proportions. A holistic approach is needed for these situations that considers environmental conditions as well.

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

NASA Technical Reports Server (NTRS)

Gisser, D. G.; Frederick, D. K.; Lashmet, P. K.; Sandor, G. N.; Shen, C. N.; Yerazunis, S. Y.

1975-01-01

Problems related to an unmanned exploration of the planet Mars by means of an autonomous roving planetary vehicle are investigated. These problems include: design, construction and evaluation of the vehicle itself and its control and operating systems. More specifically, vehicle configuration, dynamics, control, propulsion, hazard detection systems, terrain sensing and modelling, obstacle detection concepts, path selection, decision-making systems, and chemical analyses of samples are studied. Emphasis is placed on development of a vehicle capable of gathering specimens and data for an Augmented Viking Mission or to provide the basis for a Sample Return Mission.

Description of a New Quadrigyrid Acanthocephalan from Kashmir, with Notes on Metal Analysis and Histopathology, and a Key to Species of the Subgenus Acanthosentis from the Indian Subcontinent.

PubMed

Amin, Omar M; Heckmann, Richard A; Zargar, Ummer Rashid

2017-10-01

Acanthogyrus (Acanthosentis) kashmirensis n. sp. is described from recently collected acanthocephalan specimens in the Jhelum River in northern Kashmir that are conspecific with Neoechinorhynchus kashmirensis Fotedar and Dhar, 1977 originally described in a Ph.D. thesis in 1972 from 4 species of cyprinid fishes: Tor tor Hamilton, Bangana diplostoma (Heckel) (syn. Labeo diplostoma Heckel), Labeo rohita Hamilton, and Ptychobarbus sp. Steindachner. The poor unpublished diagnosis was followed by 1 uninformative abstract in a scientific meeting in 1977. The acanthocephalan was later designated as invalid because of the lack of a formal published description and absence of information on deposited type or voucher specimens. Recent collections of specimens of the same species were made from 2 other cyprinid species of cyprinid fishes, Schizothorax plagiostomus Heckel and Schizothorax labiatus (McClelland) from the Sandran River, a tributary of the Jhelum River, in southern Kashmir. It is now possible to provide a full description of these specimens and reassign them in the subgenus Acanthosentis Verma and Datta, 1929 based on the finding of circles of vestigial spines at the anterior end of the trunk of male and female specimens. These vestigial spines are barely visible and easy to miss with optical microscopy. The new species is also characterized by having (1) a para-receptacle structure in males and females, (2) unique double Saefftigen's pouches, (3) large round single-nucleated cells in the proboscis, and (4) the lemnisci being either equal or distinctly unequal with no intermediate states. A key to the species of Acanthosentis of the Indian subcontinent is provided. Histopathological sections show extensive damage to the host intestine with subsequent blood loss, cell necrosis, and attempted encapsulation. Results of the energy dispersive X-ray analysis (EDAX) study show hollow hooks high in sulfur but with limited calcium ions. Hooks of most acanthocephalans studied with X-ray scans are solid with high calcium and low sulfur ions.

How tough is bone? Application of elastic-plastic fracture mechanics to bone.

PubMed

Yan, Jiahau; Mecholsky, John J; Clifton, Kari B

2007-02-01

Bone, with a hierarchical structure that spans from the nano-scale to the macro-scale and a composite design composed of nano-sized mineral crystals embedded in an organic matrix, has been shown to have several toughening mechanisms that increases its toughness. These mechanisms can stop, slow, or deflect crack propagation and cause bone to have a moderate amount of apparent plastic deformation before fracture. In addition, bone contains a high volumetric percentage of organics and water that makes it behave nonlinearly before fracture. Many researchers used strength or critical stress intensity factor (fracture toughness) to characterize the mechanical property of bone. However, these parameters do not account for the energy spent in plastic deformation before bone fracture. To accurately describe the mechanical characteristics of bone, we applied elastic-plastic fracture mechanics to study bone's fracture toughness. The J integral, a parameter that estimates both the energies consumed in the elastic and plastic deformations, was used to quantify the total energy spent before bone fracture. Twenty cortical bone specimens were cut from the mid-diaphysis of bovine femurs. Ten of them were prepared to undergo transverse fracture and the other 10 were prepared to undergo longitudinal fracture. The specimens were prepared following the apparatus suggested in ASTM E1820 and tested in distilled water at 37 degrees C. The average J integral of the transverse-fractured specimens was found to be 6.6 kPa m, which is 187% greater than that of longitudinal-fractured specimens (2.3 kPa m). The energy spent in the plastic deformation of the longitudinal-fractured and transverse-fractured bovine specimens was found to be 3.6-4.1 times the energy spent in the elastic deformation. This study shows that the toughness of bone estimated using the J integral is much greater than the toughness measured using the critical stress intensity factor. We suggest that the J integral method is a better technique in estimating the toughness of bone.

Design and construction of a full-scale lateral impact testing facility.

DOT National Transportation Integrated Search

2015-05-01

The goal of this work is to design and construct a full scale lateral impact testing facility that is capable of recreating the damage that would be created by an overheight vehicle collision. This was accomplished by impacting a test specimen with 8...

Subcomponent tests for composite fuselage technology readiness

NASA Technical Reports Server (NTRS)

Madan, R. C.; Hawley, A. V.

1989-01-01

An account is given of a NASA research effort aimed at the development of an all-composite transport aircraft fuselage incorporating joints and cutouts which meets all design requirements. The design, construction, and analysis activities associated with the 30-ft-long fuselage section gave attention to critically important subcomponent specimens, including shear-tee pulloff specimens, stiffened and unstiffened cutout panels, longitudinal and transverse skin splices, longeron runouts, transverse skin-longerons, stiffened shear panels, and window belt panels. The analysis of large cutouts was conducted with coupling FEM analyses incorporating accurate failure criteria for tension and shear; the strategic application of S2 glass fiber plies around cutouts was demonstrated both analytically and experimentally to increase load capacity with virtually no weight penalty.

Development of a precision, six-axis laboratory dynamometer

NASA Technical Reports Server (NTRS)

Champagne, P. J.; Cordova, S. A.; Jacoby, M. S.; Lorell, K. R.

1992-01-01

This paper describes the design, fabrication, test, and operation of a unique six axis force/torque dynamometer The specimen table used to hold components under test is supported in a full six axis kinematic mount. Support struts fabricated from high strength steel with special integral two axis flexures link the specimen table to the load cell transducers. Realtime force/torque coordinate transform, root mean squared calculation, and data averaging, and color six axis display with controllable scaling are provided by a specially programmed desktop computer. The extensive structural analysis and design optimization required to obtain a stiff, well damped, lightweight structure is described in detail. Geometric optimization of the kinematic mount and fabrication details of the struts are also described.

Impact of HIV type 1 subtype variation on viral RNA quantitation.

PubMed

Parekh, B; Phillips, S; Granade, T C; Baggs, J; Hu, D J; Respess, R

1999-01-20

We evaluated the performance of three HIV-1 RNA quantitation methods (Amplicor HIV-1 MONITOR-1.0, NASBA, and Quantiplex HIV RNA 2.0 [branched DNA (bDNA)]) using plasma specimens (N = 60) from individuals from Asia and Africa infected with one of three HIV-1 subtypes (A, Thai B [B'] or E; N = 20 each). Our results demonstrate that of the 20 subtype A specimens, 19 were quantifiable by the bDNA assay compared with 15 by the MONITOR-1.0 and 13 by NASBA. Of those quantifiable, the mean log10 difference was 0.93 between bDNA and MONITOR-1.0 and 0.46 between bDNA and NASBA. For subtype B' specimens, the correlation among methods was better with only 2 specimens missed by NASBA and 3 by the bDNA assay. However the missed specimens had viral burden near the lower limit (1000 copies/ml) for these assays. For the 20 subtype E specimens, MONITOR-1.0 and NASBA quantified RNA in 17 and 14 specimens, respectively, as compared with 19 specimens quantified by the bDNA assay. The correlation among different assays, especially between bDNA/NASBA and MONITOR-1.0/NASBA, was poor, although the mean log10 difference for subtype E specimens was 0.4 between bDNA and MONITOR-1.0 and only 0.08 between bDNA and NASBA. The addition of a new primer set, designed for non-B HIV-1 subtypes, to the existing MONITOR assay (MONITOR-1.0+) resulted in RNA detection in all 60 specimens and significantly improved the efficiency of quantitation for subtypes A and E. Our data indicate that HIV-1 subtype variation can have a major influence on viral load quantitation by different methods. Periodic evaluation and modification of these quantitative methods may be necessary to ensure reliable quantification of divergent viruses.

Validity of computed tomography in predicting scaphoid screw prominence: a cadaveric study.

PubMed

Griffis, Clare E; Olsen, Cara; Nesti, Leon; Gould, C Frank; Frew, Michael; McKay, Patricia

2017-04-01

Studies of hardware protrusion into joint spaces following fracture fixation have been performed to address whether or not there is discrepancy between the actual and radiographic appearance of screw prominence. The purpose of our study was to prove that, with respect to the scaphoid, prominence as visualized on CT scan is real and not a result of metal artifact. Forty-two cadaveric wrists were separated into four allotted groups with 21 control specimens and 21 study specimens. All specimens were radiographically screened to exclude those with inherent carpal abnormalities. Acutrak® headless compression screws were placed into all specimens using an open dorsal approach. Cartilage was removed from screw insertion site at the convex surface of the scaphoid proximal pole. Control specimens had 0 mm screw head prominence. The studied specimens had 1, 2, and 3 mm head prominence measured with a digital caliper. Computed tomography, with direct sagittal acquisition and metal suppression technique, was then performed on all specimens following screw placement. Two staff radiologists blinded to the study groups interpreted the images. Results revealed that only one of 21 control specimens was interpreted as prominent. Comparatively, in the studied groups, 90% were accurately interpreted as prominent. CT provides an accurate assessment of scaphoid screw head prominence. When a screw appears prominent on CT scan, it is likely to be truly prominent without contribution from metallic artifact.

The influence of build parameters on the microstructure during electron beam melting of Titanium6Aluminum4Vanadium

NASA Astrophysics Data System (ADS)

Puebla, Karina

With the demand of devices to replace or improve areas, such as: electronic, biomedical and aerospace industries. Improvements in these areas of engineering have been in need due to the customer's needs for product properties requirements. The design of components must exhibit better material properties (mechanical or biocompatible) close to those of any given product. Rapid prototyping (RP) technologies that were originally designed to build prototypes may now be required to build functional end-use products. To carry out the transition, from RP to rapid manufacturing (RM), the available materials utilized in RP must provide the performance required for RM. The specific technology being used should be capable of producing reliable parts in regards to their mechanical properties. The research presented in this work investigated the effects of building parameters (build orientation and melt scan rate) on microstructure and the mechanical properties of test specimens fabricated via Electron Beam Melting (EBM) using Ti6Al4V. EBM, a rapid prototyping technology, has the potential to manufacture complex 3-dimensional end-use products layer-by-layer. In this work, a design of experiments approach was performed to determine the effects of build orientation and melt scan rate on both the microstructure and mechanical properties of test samples fabricated using EBM. Two randomized setups were designed to build two batches of 18 specimens. The experimental designs were carried out to determine the effect of different build parameters (build orientation and melt scan rate) in the mechanical properties of the fabricated specimens. The results demonstrated that EBM manufactured specimens built with different melt scan rates and build orientations have different microstructures and mechanical properties. Different melt scans produced variations in particle sintering resulting in dissimilar porosities and in mechanical properties (hardness and tensile testing). The mechanical properties decreased as the porosity increased for tensile testing and Rockwell C-scale (HR C), while Vickers hardness (HV) measurements increased and are related to the microstructure. The different build orientations of the specimens produced different mechanical properties since the orientation of the fabricated specimens impact the local heat transfer flow. This influenced the microstructure where the specimens oriented horizontally cooled more rapidly than those built vertically. Statistically significant differences in mechanical properties were found as an effect of melt scan rate. The statistical analyses that were done can help identify and classify fabrication parameters on mechanical properties for EBM-fabricated products. Optical images demonstrated the presence of alpha and beta phases, and alpha'-martensite with slight differences in microstructure. Dislocation substructures were observed in acicular alpha-plates from TEM images and alpha, beta, and alpha'-phase features. Mechanical and thermal treatment on Ti6Al4V can generate different microstructures promoting Ti6Al4V as an evolutionary alloy. Tailored mechanical properties of complex 3-dimensional end-use products can be achieved by modifying the building parameters of the EBM system. The EBM system can facilitate the process of manufacturing components by varying build parameters in order to obtain desirable physical and mechanical properties. Once the desired properties for Ti6Al4V are established, the fabrication process will lead to more successful end-use products.

Offshore Wind Turbines Subjected to Hurricanes

NASA Astrophysics Data System (ADS)

Amirinia, Gholamreza

Hurricane Andrew (1992) caused one of the largest property losses in U.S. history, but limited availability of surface wind measurements hindered the advancement of wind engineering research. Many studies have been conducted on regular boundary layer winds (non-hurricane winds) and their effects on the structures. In this case, their results were used in the standards and codes; however, hurricane winds and their effects on the structures still need more studies and observations. Analysis of hurricane surface winds revealed that turbulence spectrum of hurricane winds differs from that of non-hurricane surface winds. Vertical profile of wind velocity and turbulence intensity are also important for determining the wind loads on high-rise structures. Vertical profile of hurricane winds is affected by different parameters such as terrain or surface roughness. Recent studies show that wind velocity profile and turbulence intensity of hurricane winds may be different from those used in the design codes. Most of the studies and available models for analyzing wind turbines subjected to high-winds neglect unsteady aerodynamic forces on a parked wind tower. Since the blade pitch angle in a parked wind turbine is usually about 90°, the drag coefficient on blade airfoils are very small therefore the along-wind aerodynamic forces on the blades are smaller than those on the tower. Hence, the tower in parked condition plays an important role in along-wind responses of the wind turbine. The objectives of this study are, first, to explore the nature of the hurricane surface winds. Next, to establish a time domain procedure for addressing structure-wind-wave-soil interactions. Third, investigating the behavior of wind turbines subjected to hurricane loads resulted form hurricane nature and, lastly, to investigate reconfiguration of turbine structure to reduce wind forces. In order to achieve these objective, first, recent observations on hurricane turbulence models were discussed. Then a new formulation for addressing unsteady wind forces on the tower was introduced and NREL-FAST package was modified with the new formulation. Interaction of wind-wave-soil-structure was also included in the modification. After customizing the package, the tower and blade buffeting responses, the low cycle fatigue during different hurricane categories, and extreme value of the short-term responses were analyzed. In the second part, piezoelectric materials were used to generate perturbations on the surface of a specimen in the wind tunnel. This perturbation was used to combine upward wall motion and surface curvature. For this purpose, a Macro Fiber Composite (MFC) material was mounted on the surface of a cylindrical specimen for generating perturbation in the wind tunnel. Four different perturbation frequencies (1 Hz, 2 Hz, 3 Hz, and 4Hz) as well as the baseline specimen were tested in a low-speed wind tunnel (Re= 2.8x104). Results showed that recently observed turbulence models resulted in larger structural responses and low-cycle fatigue damage than existing models. In addition, extreme value analysis of the short-term results showed that the IEC 61400-3 recommendation for wind turbine class I was sufficient for designing the tower for wind turbine class S subjected to hurricane; however, for designing the blade, IEC 61400-3 recommendations for class I underestimated the responses. In addition, wind tunnel testing results showed that the perturbation of the surface of the specimen increased the turbulence in the leeward in specific distance from the specimen. The surface perturbation technique had potential to reduce the drag by 4.8%.

Comparison between Saliva and Nasopharyngeal Swab Specimens for Detection of Respiratory Viruses by Multiplex Reverse Transcription-PCR

PubMed Central

Kim, Young-gon; Kim, Min Young; Park, Kwisung; Cho, Chi Hyun; Yoon, Soo Young; Nam, Myung Hyun; Lee, Chang Kyu; Cho, Yun-Jung; Lim, Chae Seung

2016-01-01

ABSTRACT Nasopharyngeal swabs (NPSs) are being widely used as specimens for multiplex real-time reverse transcription (RT)-PCR for respiratory virus detection. However, it remains unclear whether NPS specimens are optimal for all viruses targeted by multiplex RT-PCR. In addition, the procedure to obtain NPS specimens causes coughing in most patients, which possibly increases the risk of nosocomial spread of viruses. In this study, paired NPS and saliva specimens were collected from 236 adult male patients with suspected acute respiratory illnesses. Specimens were tested for 16 respiratory viruses by multiplex real-time RT-PCR. Among the specimens collected from the 236 patients, at least 1 respiratory virus was detected in 183 NPS specimens (77.5%) and 180 saliva specimens (76.3%). The rates of detection of respiratory viruses were comparable for NPS and saliva specimens (P = 0.766). Nine virus species and 349 viruses were isolated, 256 from NPS specimens and 273 from saliva specimens (P = 0.1574). Adenovirus was detected more frequently in saliva samples (P < 0.0001), whereas influenza virus type A and human rhinovirus were detected more frequently in NPS specimens (P = 0.0001 and P = 0.0289, respectively). The possibility of false-positive adenovirus detection from saliva samples was excluded by direct sequencing. In conclusion, neither of the sampling methods was consistently more sensitive than the other. We suggest that these cost-effective methods for detecting respiratory viruses in mixed NPS-saliva specimens might be valuable for future studies. PMID:27807150

Modeling and Characterization of Dynamic Failure of Soda-lime Glass Under High Speed Impact

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

Liu, Wenning N.; Sun, Xin; Chen, Weinong W.

2012-05-27

In this paper, the impact-induced dynamic failure of a soda-lime glass block is studied using an integrated experimental/analytical approach. The Split Hopkinson Pressure Bar (SHPB) technique is used to conduct dynamic failure test of soda-lime glass first. The damage growth patterns and stress histories are reported for various glass specimen designs. Making use of a continuum damage mechanics (CDM)-based constitutive model, the initial failure and subsequent stiffness reduction of glass are simulated and investigated. Explicit finite element analyses are used to simulate the glass specimen impact event. A maximum shear stress-based damage evolution law is used in describing the glassmore » damage process under combined compression/shear loading. The impact test results are used to quantify the critical shear stress for the soda-lime glass under examination.« less

Evaluation of wheelchair drop seat crashworthiness.

PubMed

Bertocci, G; Ha, D; van Roosmalen, L; Karg, P; Deemer, E

2001-05-01

Wheelchair seating crash performance is critical to protecting wheelchair users who remain seated in their wheelchairs during transportation. Relying upon computer simulation and sled testing seat loads associated with a 20 g/48 kph (20 g/30 mph) frontal impact and 50th percentile male occupant were estimated to develop test criteria. Using a static test setup we evaluated the performance of various types of commercially available drop seats against the loading test criteria. Five different types of drop seats (two specimens each) constructed of various materials (i.e. plastics, plywood, metal) were evaluated. Two types of drop seats (three of the total 10 specimens) met the 16650 N (3750 lb) frontal impact test criteria. While additional validation of the test protocol is necessary, this study suggests that some drop seat designs may be incapable of withstanding crash level loads.

A New High-Speed, High-Cycle, Gear-Tooth Bending Fatigue Test Capability

NASA Technical Reports Server (NTRS)

Stringer, David B.; Dykas, Brian D.; LaBerge, Kelsen E.; Zakrajsek, Andrew J.; Handschuh, Robert F.

2011-01-01

A new high-speed test capability for determining the high cycle bending-fatigue characteristics of gear teeth has been developed. Experiments were performed in the test facility using a standard spur gear test specimens designed for use in NASA Glenn s drive system test facilities. These tests varied in load condition and cycle-rate. The cycle-rate varied from 50 to 1000 Hz. The loads varied from high-stress, low-cycle loads to near infinite life conditions. Over 100 tests were conducted using AISI 9310 steel spur gear specimen. These results were then compared to previous data in the literature for correlation. Additionally, a cycle-rate sensitivity analysis was conducted by grouping the results according to cycle-rate and comparing the data sets. Methods used to study and verify load-path and facility dynamics are also discussed.

Heterophilic interference in specimens yielding false-reactive results on the Abbott 4th generation ARCHITECT HIV Ag/Ab Combo assay.

PubMed

Lavoie, S; Caswell, D; Gill, M J; Kadkhoda, K; Charlton, C L; Levett, P N; Hatchette, T; Garceau, R; Maregmen, J; Mazzulli, T; Needle, R; Kadivar, K; Kim, J

2018-07-01

False-reactivity in HIV-negative specimens has been detected in HIV fourth-generation antigen/antibody or 'combo' assays which are able to detect both anti-HIV-1/HIV-2 antibodies and HIV-1 antigen. We sought to characterize these specimens and determine the effect of heterophilic interference. Specimens previously testing as false-reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay and re-tested on a different (Siemens ADVIA Centaur HIV Ag/Ab) assay. A subset of these specimens were also pre-treated with heterophilic blocking agents and re-tested on the Abbott assay. Here we report that 95% (252/264) of clinical specimens that were repeatedly reactive on the Abbott ARCHITECT HIV Ag/Ab combo assay (S/Co range, 0.94-678) were negative when re-tested on a different fourth generation HIV combo assay (Siemens ADVIA Centaur HIV Ag/Ab). All 264 samples were subsequently confirmed to be HIV negative. On a small subset (57) of specimens with available volume, pre-treatment with two different reagents (HBT; Heterophilic Blocking Tube, NABT; Non-Specific Blocking Tube) designed to block heterophilic antibody interference either eliminated (HBT) or reduced (NABT) the false reactivity when re-tested on the ARCHITECT HIV Ag/Ab combo assay. Our results suggest that the Abbott ARCHITECT HIV Ag/Ab combo assay can be prone to heterophilic antibody interference. Crown Copyright © 2018. Published by Elsevier B.V. All rights reserved.

Design of Experiments for Model Calibration of Multi-Physics Systems with Targeted Events of Interest

DTIC Science & Technology

2017-03-01

discrete set of specimen and instrumentation locations available to be studied in a high -speed tunnel, such as the 8-foot HTT, under the desired...Benjamin P. Smarslok Hypersonic Sciences Branch High Speed Systems Division Diane Villanueva Universal Technology Corporation MARCH 2017...and is available to the general public, including foreign nationals. Copies may be obtained from the Defense Technical Information Center (DTIC

Microleakage of composite crowns luted on CAD/CAM-milled human molars: a new method for standardized in vitro tests.

PubMed

Schlenz, Maximiliane Amelie; Schmidt, Alexander; Rehmann, Peter; Niem, Thomas; Wöstmann, Bernd

2018-04-24

To investigate debonding of full crowns made of CAD/CAM composites, CAD/CAM technology was applied to manufacture standardized test abutments to increase the reproducibility of human teeth used in in vitro studies. A virtual test abutment and the corresponding virtual crown were designed and two STL data sets were generated. Sixty-four human third molars and CAD/CAM blocks were milled using a CNC machine. Crowns of four different composite blocks (Lava Ultimate (LU), Brilliant Crios (BC), Cerasmart (CS), Experimental (EX)) were adhesively bonded with their corresponding luting system (LU: Scotchbond Universal/RelyX Ultimate; BC: One Coat 7 Universal/DuoCem; CS: G-PremioBond/G-Cem LinkForce; EX: Experimental-Bond/Experimental-Luting-Cement). Half of the specimens were chemical-cured (CC) and the others were light-cured (LC). Afterwards, specimens were artificially aged in a chewing simulator (WL-tec, 1 million cycles, 50-500 N, 2 Hz, 37 °C). Finally, a dye penetration test was used to detect debonding. For inspection, the specimens were sliced, and penetration depth was measured with a digital microscope. Data were analyzed with the Mann-Whitney U test. No cases of total debonding were observed after cyclic loading. However, the LC specimens showed a significantly lower amount of leakage than the CC ones (p < 0.05). Furthermore, the CC specimens exhibited broad scattering. Only the LC-EX blocks showed no debonding. The CC-CS blocks showed the highest leakage and scattering of all tested specimens. Natural human teeth can be manufactured by CAD/CAM technology in highly standardized test abutments for in vitro testing. For CAD/CAM composites, light curing should be performed. The success of a restoration depends on the long-term sealing ability of the luting materials, which avoids debonding along with microleakage. For CAD/CAM composites, separate light curing of the adhesive and luting composite is highly recommended.

Recombinant antigen-based antibody assays for the diagnosis and surveillance of lymphatic filariasis – a multicenter trial

PubMed Central

Lammie, Patrick J; Weil, Gary; Noordin, Rahmah; Kaliraj, Perumal; Steel, Cathy; Goodman, David; Lakshmikanthan, Vijaya B; Ottesen, Eric

2004-01-01

The development of antifilarial antibody responses is a characteristic feature of infection with filarial parasites. It should be possible to exploit this fact to develop tools to monitor the progress of the global program to eliminate lymphatic filariasis (LF); however, assays based on parasite extracts suffer from a number of limitations, including the paucity of parasite material, the difficulty of assay standardization and problems with assay specificity. In principle, assays based on recombinant filarial antigens should address these limitations and provide useful tools for diagnosis and surveillance of LF. The present multicenter study was designed to compare the performance of antibody assays for filariasis based on recombinant antigens Bm14, WbSXP, and BmR1. Coded serum specimens were distributed to five participating laboratories where assays for each antigen were conducted in parallel. Assays based on Bm14, WbSXP, or BmR1 demonstrated good sensitivity (>90%) for field use and none of the assays demonstrated reactivity with specimens from persons with non-filarial helminth infections. Limitations of the assays are discussed. Well-designed field studies are now needed to assess sampling methodology and the application of antibody testing to the monitoring and surveillance of LF elimination programs. PMID:15347425

Particle size and morphology of UHMWPE wear debris in failed total knee arthroplasties--a comparison between mobile bearing and fixed bearing knees.

PubMed

Huang, Chun-Hsiung; Ho, Fang-Yuan; Ma, Hon-Ming; Yang, Chan-Tsung; Liau, Jiann-Jong; Kao, Hung-Chan; Young, Tai-Horng; Cheng, Cheng-Kung

2002-09-01

Osteolysis induced by ultrahigh molecular weight polyethylene wear debris has been recognized as the major cause of long-term failure in total joint arthroplasties. In a previous study, the prevalence of intraoperatively identified osteolysis during primary revision surgery was much higher in mobile bearing knee replacements (47%) than in fixed bearing knee replacements (13%). We postulated that mobile bearing knee implants tend to produce smaller sized particles. In our current study, we compared the particle size and morphology of polyethylene wear debris between failed mobile bearing and fixed bearing knees. Tissue specimens from interfacial and lytic regions were extracted during revision surgery of 10 mobile bearing knees (all of the low contact stress (LCS) design) and 17 fixed bearing knees (10 of the porous-coated anatomic (PCA) and 7 of the Miller/Galante design). Polyethylene particles were isolated from the tissue specimens and examined using both scanning electron microscopy and light-scattering analyses. The LCS mobile bearing knees produced smaller particulate debris (mean equivalent spherical diameter: 0.58 microm in LCS, 1.17 microm in PCA and 5.23 microm in M/G) and more granular debris (mean value: 93% in LCS, 77% in PCA and 15% in M/G).

Herpetological Monitoring Using a Pitfall Trapping Design in Southern California

USGS Publications Warehouse

Fisher, Robert; Stokes, Drew; Rochester, Carlton; Brehme, Cheryl; Hathaway, Stacie; Case, Ted

2008-01-01

The steps necessary to conduct a pitfall trapping survey for small terrestrial vertebrates are presented. Descriptions of the materials needed and the methods to build trapping equipment from raw materials are discussed. Recommended data collection techniques are given along with suggested data fields. Animal specimen processing procedures, including toe- and scale-clipping, are described for lizards, snakes, frogs, and salamanders. Methods are presented for conducting vegetation surveys that can be used to classify the environment associated with each pitfall trap array. Techniques for data storage and presentation are given based on commonly use computer applications. As with any study, much consideration should be given to the study design and methods before beginning any data collection effort.

Content-based analysis of Ki-67 stained meningioma specimens for automatic hot-spot selection.

PubMed

Swiderska-Chadaj, Zaneta; Markiewicz, Tomasz; Grala, Bartlomiej; Lorent, Malgorzata

2016-10-07

Hot-spot based examination of immunohistochemically stained histological specimens is one of the most important procedures in pathomorphological practice. The development of image acquisition equipment and computational units allows for the automation of this process. Moreover, a lot of possible technical problems occur in everyday histological material, which increases the complexity of the problem. Thus, a full context-based analysis of histological specimens is also needed in the quantification of immunohistochemically stained specimens. One of the most important reactions is the Ki-67 proliferation marker in meningiomas, the most frequent intracranial tumour. The aim of our study is to propose a context-based analysis of Ki-67 stained specimens of meningiomas for automatic selection of hot-spots. The proposed solution is based on textural analysis, mathematical morphology, feature ranking and classification, as well as on the proposed hot-spot gradual extinction algorithm to allow for the proper detection of a set of hot-spot fields. The designed whole slide image processing scheme eliminates such artifacts as hemorrhages, folds or stained vessels from the region of interest. To validate automatic results, a set of 104 meningioma specimens were selected and twenty hot-spots inside them were identified independently by two experts. The Spearman rho correlation coefficient was used to compare the results which were also analyzed with the help of a Bland-Altman plot. The results show that most of the cases (84) were automatically examined properly with two fields of view with a technical problem at the very most. Next, 13 had three such fields, and only seven specimens did not meet the requirement for the automatic examination. Generally, the Automatic System identifies hot-spot areas, especially their maximum points, better. Analysis of the results confirms the very high concordance between an automatic Ki-67 examination and the expert's results, with a Spearman rho higher than 0.95. The proposed hot-spot selection algorithm with an extended context-based analysis of whole slide images and hot-spot gradual extinction algorithm provides an efficient tool for simulation of a manual examination. The presented results have confirmed that the automatic examination of Ki-67 in meningiomas could be introduced in the near future.

Impact of specimen adequacy on the assessment of renal allograft biopsy specimens.

PubMed

Cimen, S; Geldenhuys, L; Guler, S; Imamoglu, A; Molinari, M

2016-01-01

The Banff classification was introduced to achieve uniformity in the assessment of renal allograft biopsies. The primary aim of this study was to evaluate the impact of specimen adequacy on the Banff classification. All renal allograft biopsies obtained between July 2010 and June 2012 for suspicion of acute rejection were included. Pre-biopsy clinical data on suspected diagnosis and time from renal transplantation were provided to a nephropathologist who was blinded to the original pathological report. Second pathological readings were compared with the original to assess agreement stratified by specimen adequacy. Cohen's kappa test and Fisher's exact test were used for statistical analyses. Forty-nine specimens were reviewed. Among these specimens, 81.6% were classified as adequate, 6.12% as minimal, and 12.24% as unsatisfactory. The agreement analysis among the first and second readings revealed a kappa value of 0.97. Full agreement between readings was found in 75% of the adequate specimens, 66.7 and 50% for minimal and unsatisfactory specimens, respectively. There was no agreement between readings in 5% of the adequate specimens and 16.7% of the unsatisfactory specimens. For the entire sample full agreement was found in 71.4%, partial agreement in 20.4% and no agreement in 8.2% of the specimens. Statistical analysis using Fisher's exact test yielded a P value above 0.25 showing that - probably due to small sample size - the results were not statistically significant. Specimen adequacy may be a determinant of a diagnostic agreement in renal allograft specimen assessment. While additional studies including larger case numbers are required to further delineate the impact of specimen adequacy on the reliability of histopathological assessments, specimen quality must be considered during clinical decision making while dealing with biopsy reports based on minimal or unsatisfactory specimens.

Cohesive fracture of elastically heterogeneous materials: An integrative modeling and experimental study

NASA Astrophysics Data System (ADS)

Wang, Neng; Xia, Shuman

2017-01-01

A combined modeling and experimental effort is made in this work to examine the cohesive fracture mechanisms of heterogeneous elastic solids. A two-phase laminated composite, which mimics the key microstructural features of many tough engineering and biological materials, is selected as a model material system. Theoretical and finite element analyses with cohesive zone modeling are performed to study the effective fracture resistance of the heterogeneous material associated with unstable crack propagation and arrest. A crack-tip-position controlled algorithm is implemented in the finite element analysis to overcome the inherent instability issues resulting from crack pinning and depinning at local heterogeneities. Systematic parametric studies are carried out to investigate the effects of various material and geometrical parameters, including the modulus mismatch ratio, phase volume fraction, cohesive zone size, and cohesive law shape. Concurrently, a novel stereolithography-based three-dimensional (3D) printing system is developed and used for fabricating heterogeneous test specimens with well-controlled structural and material properties. Fracture testing of the specimens is performed using the tapered double-cantilever beam (TDCB) test method. With optimal material and geometrical parameters, heterogeneous TDCB specimens are shown to exhibit enhanced effective fracture energy and effective fracture toughness than their homogeneous counterparts, which is in good agreement with the modeling predictions. The integrative computational and experimental study presented here provides a fundamental mechanistic understanding of the fracture mechanisms in brittle heterogeneous materials and sheds light on the rational design of tough materials through patterned heterogeneities.

16 CFR 1616.4 - Sampling and acceptance procedures.

Code of Federal Regulations, 2011 CFR

2011-01-01

... specimen to one of the three samples. Test each set of three samples and accept or reject each seam design... all the test criteria of § 1616.3(b), accept the seam design. If one or more of the three additional.... Test the sets of three samples and accept or reject the type of trim and design on the same basis as...

16 CFR 1616.4 - Sampling and acceptance procedures.

Code of Federal Regulations, 2012 CFR

2012-01-01

... specimen to one of the three samples. Test each set of three samples and accept or reject each seam design... all the test criteria of § 1616.3(b), accept the seam design. If one or more of the three additional.... Test the sets of three samples and accept or reject the type of trim and design on the same basis as...

16 CFR 1616.4 - Sampling and acceptance procedures.

Code of Federal Regulations, 2010 CFR

2010-01-01

... specimen to one of the three samples. Test each set of three samples and accept or reject each seam design... all the test criteria of § 1616.3(b), accept the seam design. If one or more of the three additional.... Test the sets of three samples and accept or reject the type of trim and design on the same basis as...

Microfluidics enables multiplex evaluation of the same cells for further studies.

PubMed

Mojica, W D; Oh, K W; Lee, H; Furlani, E P; Sykes, D; Sands, A M

2016-08-01

The continuous discovery of biomarkers and their evolving use for the diagnosis and guidance of therapy for patients with cancer has increased awareness of the need to triage biospecimens properly. On occasion, cytology samples are the only type of biospecimen available for analysis. Often, the current approach for these latter specimens is cytopathology-centric, with cells limited to examination by bright field microscopy. When specimens are paucicellular, there is often insufficient material for ancillary testing. Therefore, a need exists to develop an alternative approach that allows for the multiplexed analysis of cells when they are limited in number. In recent previous publications, we demonstrated that clinically derived cells from tissue are suitable for evaluation in a microfluidic device. In our current endeavour, we seek to expand upon those findings and determine if those same cells can be recovered for further analysis. A microfluidic channel was designed, fabricated and tested using cytology specimens generated from tissue specimens. The cytological features of the cells tested were examined prior to entering the channel; they were then compared to similar cells while in the channel, and upon recovery from the channel. Recovery of DNA and proteins were also tested. The morphology of the tested cells was not compromised in either the channel or upon recovery. More importantly, the integrity of the cells remained intact, with the recovery of proteins and high molecular weight DNA possible. We developed and tested an alternative approach to the processing of cytopathology specimens that enables multiplexed evaluation. Using microfluidics, cytological examination of biopecimens can be performed, but in contrast to existing approaches, the same cells examined can be recovered for downstream analysis. © 2015 John Wiley & Sons Ltd.

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

DOE PAGES

Duan, R.; Jalowicka, Aleksandra; Unocic, Kinga A.; ...

2016-10-18

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up tomore » 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.« less

Electrical conductance sensitivity functions for square and circular cloverleaf van der Pauw geometries

NASA Astrophysics Data System (ADS)

Koon, Daniel W.; Heřmanová, Martina; Náhlík, Josef

2015-11-01

We have undertaken the first systematic computational and experimental study of the sensitivity of charge transport measurement to local physical defects for van der Pauw circular and square cloverleafs with rounded internal corners and unclovered geometries, using copper-foil specimens. Cloverleafs with rounded internal corners are in common use and reduce sampling of the material near their boundaries, an advantage over sharp corners. We have defined two parameters for these cloverleafs, one of which, the ‘admittance’, is the best predictor of the sensitivity at the center of these specimens, with this sensitivity depending only weakly on the central ‘core’ size when its diameter is less than about 60% of the specimen’s lateral size. Resistive measurement errors in all four geometries are linear in areas for errors up to about 50% in sheet resistance, and superlinear above. An ASTM-based ‘standard’ cloverleaf geometry, in which the central core diameter of the specimen is 1/5 the overall length and the slit widths are 1/10 the overall length, narrows the effective area sampled by the resistive measurement by a factor of about 16  ×  in the small-hole limit and over 40  ×  for larger holes, relative to unclovered goemetries, whether square or circular, with a smooth transition in these numbers for geometries intermediate between the standard cloverleaf and unclovered specimens. We believe that this work will allow materials scientists to better estimate the impact of factors such as the uniformity of film thickness and of material purity on their measurements, and allow sensor designers to better choose an optimal specimen geometry.

Predicting oxidation-limited lifetime of thin-walled components of NiCrW alloy 230

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

Duan, R.; Jalowicka, Aleksandra; Unocic, Kinga A.

Using alloy 230 as an example, a generalized oxidation lifetime model for chromia-forming Ni-base wrought alloys is proposed, which captures the most important damaging oxidation effects relevant for component design: wall thickness loss, scale spallation, and the occurrence of breakaway oxidation. For deriving input parameters and for verification of the model approach, alloy 230 specimens with different thicknesses were exposed for different times at temperatures in the range 950–1050 °C in static air. The studies focused on thin specimens (0.2–0.5 mm) to obtain data for critical subscale depletion processes resulting in breakaway oxidation within reasonably achievable test times up tomore » 3000 h. The oxidation kinetics and oxidation-induced subscale microstructural changes were determined by combining gravimetric data with results from scanning electron microscopy with energy dispersive X-ray spectroscopy. The modeling of the scale spallation and re-formation was based on the NASA cyclic oxidation spallation program, while a new model was developed to describe accelerated oxidation occurring after longer exposure times in the thinnest specimens. The calculated oxidation data were combined with the reservoir model equation, by means of which the relation between the consumption and the remaining concentration of Cr in the alloy was established as a function of temperature and specimen thickness. Based on this approach, a generalized lifetime diagram is proposed, in which wall thickness loss is plotted as a function of time, initial specimen thickness, and temperature. As a result, the time to reach a critical Cr level at the scale/alloy interface of 10 wt% is also indicated in the diagrams.« less