Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association, Jan 24, 2016
To compare femoral nerve block (FNB) versus local liposomal bupivacaine (LB) for pain control in ... more To compare femoral nerve block (FNB) versus local liposomal bupivacaine (LB) for pain control in patients undergoing anterior cruciate ligament (ACL) reconstruction. Eighty-five patients undergoing primary ACL reconstruction were assessed for participation. We performed a prospective randomized trial in accordance with the CONSORT (Consolidated Standards of Reporting Trials) 2010 statement. The study arms included either intraoperative local infiltration of LB (20 mL of bupivacaine/10 mL of saline solution) or preoperative FNB with a primary outcome of postoperative pain levels (visual analog scale) for 4 days. Secondary outcomes assessed included opioid consumption (intravenous morphine equivalents), hours slept, patient satisfaction, and calls to the physician. Randomization was by a computerized algorithm. The observer was blinded and the patient was not blinded to the intervention. One patient declined participation; 2 patients were excluded after randomization. A total of 82 pa...
Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space ... more Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space heat rejection systems. These heat pipes would be incorporated into a large radiator for waste heat rejection from a space nuclear power source. Current fabrication technology limits the heat pipes to straight lengths, although different cross-sections can be fabricated. A radiator analytical model was developed and used to examine the effects of fin pipe cross-section and fin material on radiator mass. Carbon-Carbon, Compglas, and beryllia fins were examined. The overall radiator mass was only slightly affected by the choice of material, however, the carbon-carbon design required fewer fin heat pipes. Radiators with carbon-glass composite (Compglas) fins had a slightly higher mass, but may still be attractive based on the other properties of Compglas, including resistance to atomic oxygen, and the ability to be fabricated into thin sheets. Square Nb/Alumina tubes have already been fabricated, while rectangular niobium composite tube is under development. These tubes will be bonded to carbon-carbon or Compglas fins, and fabricated into sodium heat pipes.
We have measured local variations in microtexture and grain boundary misorientation in narrow, pa... more We have measured local variations in microtexture and grain boundary misorientation in narrow, passivated copper interconnects, using electron backscatter diffraction. This allowed us to differentiate between the local crystallography associated with voids and that associated with regions remaining intact during thermal treatment, all within the same lines. In general, grain boundaries intersecting voids exhibited structures that provided more favorable kinetic pathways for atom migration than those boundaries present within intact regions of the same line. Specifically, grains near voids showed a locally weaker <111> texture than those in unvoided regions. Boundaries between such grains were more likely to be of twist character and of higher angle character than those in unvoided regions. Such boundaries, when of tilt character, were more likely to have misorientation axes parallel to the film plane. Local variations in crystallography are shown to play an important role in determining interconnect reliability.
We have simultaneously measured the range and multiple scattering of muons of kinetic energies be... more We have simultaneously measured the range and multiple scattering of muons of kinetic energies between 9 and 25 MeV from foils of steel, aluminum, and polyethylene. We have expressed, after Moliere, the root-mean-square projected angle as:
This paper describes three materials technologies, developed for space nuclear power thermal mana... more This paper describes three materials technologies, developed for space nuclear power thermal management, with exciting and varied applications in other fields. Six dual-use applications are presented. The three basic technologies are described: (1) Refractory-metal/ceramic layered composites can be made into thin, rigid, vacuum tight shells. These shells can be tailored for excellent impact resistance and/or excellent corrision/erosion properties. Dual use applications range from micrometeroid shield radiators for spacecraft to erosion resistant waste-stream heat recovery for corrosive exhaust. (2.) Porous metal technology was initially developed to produce wicks for liquid metal heat pipes.This technology is being developed in several new directions. Porous metal heat exchangers feature extraordinarily high specific surface ratios and have absorbed heat fluxes in excess of 100 MW/m2. Porous metal structures are highly compliant, so the technology has been expanded to produce a compliant interface for the attachment of materials with widely different coefficients of thermal expansion such as low expansion carbon-carbon to high expansion metals. (3.) The paper also describes a process, developed for space nuclear power (thermionics), which achieves 100&percnt; dense tungsten by plasma spraying. This could have major application in the reprocessing of spent nuclear fuel or other pyrochemical processes, where it would replace gun-drilled tungsten-molybdenum tubes with pure tungsten tubes of smaller diameter, longer, and thiner walled. The process could produce pure tungsten components in complex shapes for arcjet thrusters and other electric propulsion devices.
The damage generated by AC currents at 100 Hz in interconnects has been studied and compared with... more The damage generated by AC currents at 100 Hz in interconnects has been studied and compared with mechanical fatigue damage in thin films. The nature of the damage under the two loading conditions is qualitatively similar, supporting the idea that the AC current damage comes from mechanical cycling due to temperature swings on the order of 100 K from Joule heating in the interconnects. In both cases, the damage forms as surface wrinkles within single grains grow in amplitude and extent with time. The possible threat to the reliability of microelectronic and microelectromechanical systems is further escalated by the observation that soft encapsulation layers do nothing to retard the formation of the damage. CP612, Stress-Induced Phenomena in Metallization: Sixth International Workshop, edited by S. P. Baker, M. A. Korhonen, E. Arzt, and P. S. Ho, pp. 119-132.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, May 22, 2007
Nanoindentation is used in a variety of fields to measure material hardness and elastic modulus. ... more Nanoindentation is used in a variety of fields to measure material hardness and elastic modulus. This test technique is especially attractive for thin films because of the difficulty of conducting tensile or other conventional mechanical characterization tests on thin film specimens, and because it requires only a small surface area for testing. However, the standardization process for this new measurement method is still in progress. To test the ability of current measurement procedures to provide comparable results, a round robin was conducted. Invitations to participate were sent to over 100 laboratories. Two specimens, a copper film on a silicon substrate and an uncoated substrate, were distributed to each of 33 laboratories. The choice of measurement procedure was left to the performing organizations. By the end of the reporting period, 27 sets of results were received. While the average reported uncertainty (1 standard deviation) among the individual participants was 4 pct of the average hardness, the interlaboratory standard deviation of the hardness values was 15 pct. Similarly, the average reported uncertainty of the modulus was 5 pct of the average value, but the interlaboratory standard deviation of the modulus was 19 pct. None of the measurement variables examined in this round robin, including instrument type, analysis procedure, time since instrument calibration, chip mounting procedure, and tip condition, and neither of the potential covariant effects, chip location in the wafer and test date, were found to have a statistically significant effect on the reported hardness or modulus.
Subcooled forced convection nucleate boiling experiments with R-113 were conducted at low velocit... more Subcooled forced convection nucleate boiling experiments with R-113 were conducted at low velocities using both thin film semi-transparent gold on quartz and gold coated cooper substrate flat heaters at varying orientations. The results are intended to assist in understanding effects of buoyancy in forced convection boiling and in better defining requirements for studying flow boiling in the microgravity environment of space. Measurements of the heat flux and the surface superheat were made at three levels of subcooling from 2.2 C to 11.1 C, four bulk velocities from 4.1 cm/s to 32.4 cm/s and various orientations spanning 360 deg. The experiments demonstrate that if buoyancy is significant reative to bulk liquid momentum, then a decrease in the buoyant force normal and away from the heater surface enhances the heat transfer, with the effect being most prominent at low values of heat flux. Furthermore, the effect of velocity is shown to be dependent on the surface orientation.
... RR Keller and JM Phelps National Institute of Standards and Technology, Materials Reliability... more ... RR Keller and JM Phelps National Institute of Standards and Technology, Materials Reliability Division, 325 Broadway, Boulder, Colorado 80303 ... ACKNOWLEDGMENTS The authors thank A. Dabiran for thin film prepara-tion and J. Angelo, D. Joy, J. Mancuso, and D. Newbury ...
Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor ... more Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of $\alpha-$Al$_2$O$_3$(0001) at temperatures of 250 C to 650 C. The films were then annealed at 1000 C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by $60^{\circ}$. The in-plane epitaxial relationship for all films was $[110]_{metal}$||$[10\bar{1}0]_{{Al}_{2}{O}_{3}}$. Reactive sputtering of Al in O$_2$ before metal deposition resulted in a single in-plane orientation over 97 % of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al$_2$O$_3$ interface, confirmed the epitaxial relationship, and showed that formation of the $60^{\circ}$ twin grains was associated with features on the Al$_2$O$_3$ surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and and Cu$_x$Ni$_y$ films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO$_2$ films, but still showed thickness variations on a much smaller length scale than the distance between grains.
Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association, Jan 24, 2016
To compare femoral nerve block (FNB) versus local liposomal bupivacaine (LB) for pain control in ... more To compare femoral nerve block (FNB) versus local liposomal bupivacaine (LB) for pain control in patients undergoing anterior cruciate ligament (ACL) reconstruction. Eighty-five patients undergoing primary ACL reconstruction were assessed for participation. We performed a prospective randomized trial in accordance with the CONSORT (Consolidated Standards of Reporting Trials) 2010 statement. The study arms included either intraoperative local infiltration of LB (20 mL of bupivacaine/10 mL of saline solution) or preoperative FNB with a primary outcome of postoperative pain levels (visual analog scale) for 4 days. Secondary outcomes assessed included opioid consumption (intravenous morphine equivalents), hours slept, patient satisfaction, and calls to the physician. Randomization was by a computerized algorithm. The observer was blinded and the patient was not blinded to the intervention. One patient declined participation; 2 patients were excluded after randomization. A total of 82 pa...
Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space ... more Niobium/alumina composite materials show promise for providing low mass fin heat pipes for space heat rejection systems. These heat pipes would be incorporated into a large radiator for waste heat rejection from a space nuclear power source. Current fabrication technology limits the heat pipes to straight lengths, although different cross-sections can be fabricated. A radiator analytical model was developed and used to examine the effects of fin pipe cross-section and fin material on radiator mass. Carbon-Carbon, Compglas, and beryllia fins were examined. The overall radiator mass was only slightly affected by the choice of material, however, the carbon-carbon design required fewer fin heat pipes. Radiators with carbon-glass composite (Compglas) fins had a slightly higher mass, but may still be attractive based on the other properties of Compglas, including resistance to atomic oxygen, and the ability to be fabricated into thin sheets. Square Nb/Alumina tubes have already been fabricated, while rectangular niobium composite tube is under development. These tubes will be bonded to carbon-carbon or Compglas fins, and fabricated into sodium heat pipes.
We have measured local variations in microtexture and grain boundary misorientation in narrow, pa... more We have measured local variations in microtexture and grain boundary misorientation in narrow, passivated copper interconnects, using electron backscatter diffraction. This allowed us to differentiate between the local crystallography associated with voids and that associated with regions remaining intact during thermal treatment, all within the same lines. In general, grain boundaries intersecting voids exhibited structures that provided more favorable kinetic pathways for atom migration than those boundaries present within intact regions of the same line. Specifically, grains near voids showed a locally weaker <111> texture than those in unvoided regions. Boundaries between such grains were more likely to be of twist character and of higher angle character than those in unvoided regions. Such boundaries, when of tilt character, were more likely to have misorientation axes parallel to the film plane. Local variations in crystallography are shown to play an important role in determining interconnect reliability.
We have simultaneously measured the range and multiple scattering of muons of kinetic energies be... more We have simultaneously measured the range and multiple scattering of muons of kinetic energies between 9 and 25 MeV from foils of steel, aluminum, and polyethylene. We have expressed, after Moliere, the root-mean-square projected angle as:
This paper describes three materials technologies, developed for space nuclear power thermal mana... more This paper describes three materials technologies, developed for space nuclear power thermal management, with exciting and varied applications in other fields. Six dual-use applications are presented. The three basic technologies are described: (1) Refractory-metal/ceramic layered composites can be made into thin, rigid, vacuum tight shells. These shells can be tailored for excellent impact resistance and/or excellent corrision/erosion properties. Dual use applications range from micrometeroid shield radiators for spacecraft to erosion resistant waste-stream heat recovery for corrosive exhaust. (2.) Porous metal technology was initially developed to produce wicks for liquid metal heat pipes.This technology is being developed in several new directions. Porous metal heat exchangers feature extraordinarily high specific surface ratios and have absorbed heat fluxes in excess of 100 MW/m2. Porous metal structures are highly compliant, so the technology has been expanded to produce a compliant interface for the attachment of materials with widely different coefficients of thermal expansion such as low expansion carbon-carbon to high expansion metals. (3.) The paper also describes a process, developed for space nuclear power (thermionics), which achieves 100&percnt; dense tungsten by plasma spraying. This could have major application in the reprocessing of spent nuclear fuel or other pyrochemical processes, where it would replace gun-drilled tungsten-molybdenum tubes with pure tungsten tubes of smaller diameter, longer, and thiner walled. The process could produce pure tungsten components in complex shapes for arcjet thrusters and other electric propulsion devices.
The damage generated by AC currents at 100 Hz in interconnects has been studied and compared with... more The damage generated by AC currents at 100 Hz in interconnects has been studied and compared with mechanical fatigue damage in thin films. The nature of the damage under the two loading conditions is qualitatively similar, supporting the idea that the AC current damage comes from mechanical cycling due to temperature swings on the order of 100 K from Joule heating in the interconnects. In both cases, the damage forms as surface wrinkles within single grains grow in amplitude and extent with time. The possible threat to the reliability of microelectronic and microelectromechanical systems is further escalated by the observation that soft encapsulation layers do nothing to retard the formation of the damage. CP612, Stress-Induced Phenomena in Metallization: Sixth International Workshop, edited by S. P. Baker, M. A. Korhonen, E. Arzt, and P. S. Ho, pp. 119-132.
Metallurgical and Materials Transactions a Physical Metallurgy and Materials Science, May 22, 2007
Nanoindentation is used in a variety of fields to measure material hardness and elastic modulus. ... more Nanoindentation is used in a variety of fields to measure material hardness and elastic modulus. This test technique is especially attractive for thin films because of the difficulty of conducting tensile or other conventional mechanical characterization tests on thin film specimens, and because it requires only a small surface area for testing. However, the standardization process for this new measurement method is still in progress. To test the ability of current measurement procedures to provide comparable results, a round robin was conducted. Invitations to participate were sent to over 100 laboratories. Two specimens, a copper film on a silicon substrate and an uncoated substrate, were distributed to each of 33 laboratories. The choice of measurement procedure was left to the performing organizations. By the end of the reporting period, 27 sets of results were received. While the average reported uncertainty (1 standard deviation) among the individual participants was 4 pct of the average hardness, the interlaboratory standard deviation of the hardness values was 15 pct. Similarly, the average reported uncertainty of the modulus was 5 pct of the average value, but the interlaboratory standard deviation of the modulus was 19 pct. None of the measurement variables examined in this round robin, including instrument type, analysis procedure, time since instrument calibration, chip mounting procedure, and tip condition, and neither of the potential covariant effects, chip location in the wafer and test date, were found to have a statistically significant effect on the reported hardness or modulus.
Subcooled forced convection nucleate boiling experiments with R-113 were conducted at low velocit... more Subcooled forced convection nucleate boiling experiments with R-113 were conducted at low velocities using both thin film semi-transparent gold on quartz and gold coated cooper substrate flat heaters at varying orientations. The results are intended to assist in understanding effects of buoyancy in forced convection boiling and in better defining requirements for studying flow boiling in the microgravity environment of space. Measurements of the heat flux and the surface superheat were made at three levels of subcooling from 2.2 C to 11.1 C, four bulk velocities from 4.1 cm/s to 32.4 cm/s and various orientations spanning 360 deg. The experiments demonstrate that if buoyancy is significant reative to bulk liquid momentum, then a decrease in the buoyant force normal and away from the heater surface enhances the heat transfer, with the effect being most prominent at low values of heat flux. Furthermore, the effect of velocity is shown to be dependent on the surface orientation.
... RR Keller and JM Phelps National Institute of Standards and Technology, Materials Reliability... more ... RR Keller and JM Phelps National Institute of Standards and Technology, Materials Reliability Division, 325 Broadway, Boulder, Colorado 80303 ... ACKNOWLEDGMENTS The authors thank A. Dabiran for thin film prepara-tion and J. Angelo, D. Joy, J. Mancuso, and D. Newbury ...
Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor ... more Films of (111)-textured Cu, Ni, and Cu$_x$Ni$_y$ were evaluated as substrates for chemical vapor deposition of graphene. A metal thickness of 400 nm to 700 nm was sputtered onto a substrate of $\alpha-$Al$_2$O$_3$(0001) at temperatures of 250 C to 650 C. The films were then annealed at 1000 C in a tube furnace. X-ray and electron backscatter diffraction measurements showed all films have (111) texture but have grains with in-plane orientations differing by $60^{\circ}$. The in-plane epitaxial relationship for all films was $[110]_{metal}$||$[10\bar{1}0]_{{Al}_{2}{O}_{3}}$. Reactive sputtering of Al in O$_2$ before metal deposition resulted in a single in-plane orientation over 97 % of the Ni film but had no significant effect on the Cu grain structure. Transmission electron microscopy showed a clean Ni/Al$_2$O$_3$ interface, confirmed the epitaxial relationship, and showed that formation of the $60^{\circ}$ twin grains was associated with features on the Al$_2$O$_3$ surface. Increasing total pressure and Cu vapor pressure during annealing decreased the roughness of Cu and and Cu$_x$Ni$_y$ films. Graphene grown on the Ni(111) films was more uniform than that grown on polycrystalline Ni/SiO$_2$ films, but still showed thickness variations on a much smaller length scale than the distance between grains.
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