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Sample records for 10-cm diameter crystal

  1. Submicron diameter single crystal sapphire optical fiber

    SciTech Connect

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers is the first step in achieving optical and sensing performance on par with its fused silica counterpart.

  2. Submicron diameter single crystal sapphire optical fiber

    DOE PAGESBeta

    Hill, Cary; Homa, Daniel; Liu, Bo; Yu, Zhihao; Wang, Anbo; Pickrell, Gary

    2014-10-02

    In this work, a submicron-diameter single crystal sapphire optical fiber was demonstrated via wet acid etching at elevated temperatures. Etch rates on the order 2.3 µm/hr were achievable with a 3:1 molar ratio sulfuric-phosphoric acid solution maintained at a temperature of 343°C. A sapphire fiber with an approximate diameter of 800 nm was successfully fabricated from a commercially available fiber with an original diameter of 50 µm. The simple and controllable etching technique provides a feasible approach to the fabrication of unique waveguide structures via traditional silica masking techniques. The ability to tailor the geometry of sapphire optical fibers ismore » the first step in achieving optical and sensing performance on par with its fused silica counterpart.« less

  3. The historical trend in float zone crystal diameters and power requirements for float zoned silicon crystals

    NASA Technical Reports Server (NTRS)

    Kramer, H. G.

    1981-01-01

    The power needed to zone silicon crystals by radio frequency heating was analyzed. The heat loss mechanisms are examined. Curves are presented for power as a function of crystal diameter for commercial silicon zoning.

  4. Solar furnace satellite for large diameter crystal growth in space

    NASA Technical Reports Server (NTRS)

    Overfelt, Tony; Wells, Mark; Blake, John

    1993-01-01

    Investigators worldwide are preparing experiments to test the influence of low gravity found in space on the growth of many crystalline materials. However, power limitations prevent existing space crystal growth furnaces from being able to process samples any larger than about 2 cm, and in addition, the background microgravity levels found on the Space Shuttle are not low enough to significantly benefit samples much larger than 2 cm. This paper describes a novel concept of a free-flying platform utilizing well-established solar furnace technology to enable materials processing in space experiments on large-diameter crystals. The conceptual design of this Solar Furnace Satellite is described along with its operational scenario and the anticipated g levels.

  5. Slip flow through colloidal crystals of varying particle diameter.

    PubMed

    Rogers, Benjamin J; Wirth, Mary J

    2013-01-22

    Slip flow of water through silica colloidal crystals was investigated experimentally for eight different particle diameters, which have hydraulic channel radii ranging from 15 to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 10(10) Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63 ± 3 nm. A flow enhancement of 20 ± 2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high-volume flow rates. PMID:23237590

  6. Slip Flow through Colloidal Crystals of Varying Particle Diameter

    PubMed Central

    Rogers, Benjamin J.; Wirth, Mary J.

    2012-01-01

    Slip flow of water through silica colloidal crystals was investigated experimentally for 8 different particle diameters, which have hydraulic channel radii ranging from 15 nm to 800 nm. The particle surfaces were silylated to be low in energy, with a water contact angle of 83°, as determined for a silylated flat surface. Flow rates through centimeter lengths of colloidal crystal were measured using a commercial liquid chromatograph for accurate comparisons of water and toluene flow rates using pressure gradients as high as 1010 Pa/m. Toluene exhibited no-slip Hagen-Poiseuille flow for all hydraulic channel radii. For water, the slip flow enhancement as a function of hydraulic channel radius was described well by the expected slip flow correction for Hagen-Poiseuille flow, and the data revealed a constant slip length of 63±3 nm. A flow enhancement of 20±2 was observed for the smallest hydraulic channel radius of 15 nm. The amount of slip flow was found to be independent of shear rate over a range of fluid velocities from 0.7 to 5.8 mm/s. The results support the applicability of the slip flow correction for channel radii as small as 15 nm. The work demonstrates that packed beds of submicrometer particles enable slip flow to be employed for high volume flow rates. PMID:23237590

  7. Development of crystal supporting system for diameter of 400 mm silicon crystal growth

    NASA Astrophysics Data System (ADS)

    Iida, T.; Machida, N.; Takase, N.; Takano, K.; Matsubara, J.; Shiraishi, Y.; Kuramoto, M.; Yamagishi, H.

    2001-07-01

    The purpose of this project is the development of a crystal supporting system (CSS) for silicon crystals with large diameters of 400 mm. Amongst the many technical problems the one that the Super Silicon Crystal Research Institute Corp. (SSi) has directed its energies is to support a weight in excess of the ability of the Dash neck to support this weight. After considering various solutions, we developed a CSS that mechanically supports the silicon subsidiary cone formed between the Dash neck and crystal shoulder. Using this method, an approximately 400 kg ingot was successfully grown from 500 kg of molten silicon in a 36-in. quartz crucible. We confirmed that the CSS mechanism worked correctly through the entire crystal growth process. This paper presents some of the anticipated problems in the mechanical supporting method and the corresponding solutions. Finally, results from real crystal growth to test and verify machine operation are reported.

  8. Shape estimation for online diameter calibration in Czochralski silicon crystal growth

    NASA Astrophysics Data System (ADS)

    Kimbel, Steven L.; O'Sullivan, Joseph A.

    2001-02-01

    The diameter setpoint of a growing crystal in the silicon Czochralski process is a key cost parameter, whose optimal choice depends in part upon the diameter calibration accuracy. Measurement of the crystal diameter during solidification is made remotely, due to high temperatures and vacuum vessel design. Vision systems for diameter control detect the diameter of the bright ring reflection from the silicon melt surface at the crystal meniscus, rather than the actual crystal diameter. Distortion due to the bright ring measurement would result in a destabilizing nonlinear diameter measurement even if the crystal diameter response were linear. Using a published model of the meniscus shape, two and three-dimensional modeling of the bright ring is performed, and simple approximations are made to predict the bright ring bias as a function of diameter slope. Tracking of a diameter maximum during vertical translation could provide a calibration measure, given accurate translation data. The use of deformable templates or snakes is suggested for tracking the diameter maximum, and is bench-tested to provide estimates of on-line calibration accuracy, a key parameter for selection of the optimum diameter setpoint. Implementation of the modified calibration strategy requires corrections for camera distortion, crystal thermal expansion and window diffraction.

  9. Effect of Anodic Alumina Oxide Pore Diameter on the Crystallization of Poly(butylene adipate).

    PubMed

    Sun, Xiaoli; Fang, Qunqun; Li, Huihui; Ren, Zhongjie; Yan, Shouke

    2016-04-01

    Poly(butylene adipate) (PBA) was infiltrated into the anodic alumina oxide (AAO) templates with the pore diameter of around 30, 70, and 100 nm and PBA nanotubes with different diameters were prepared. The crystallization and phase transition behavior of the obtained PBA nanotubes capped in the nanopores have been explored by using X-ray diffraction and differential scanning calorimetry. Only α-PBA crystals form in the bulk sample during nonisothermal crystallization. By contrast, predominant β-PBA crystals form in the AAO templates. The β-PBA crystals formed in the nanopores with pore diameter less than 70 nm prefer to adopt an orientation with their b-axis parallel to the long axis of the pore. During the melt recrystallization, it was found that the critical temperature (Tβ), below which pure β-crystals form, is 20 °C for bulk PBA. It drops down significantly with the pore diameter for the PBA in the AAO template. Moreover, the β-crystals in the porous template exhibit larger lattice parameters compared with the bulk crystals. By monitoring the change of β-crystals in the heating process, it was found that β-crystals in the AAO template with the pore diameter of 30 nm (D30) melt directly while the β-crystals transform to α-crystals in the template with the pore diameter of 100 nm (D100). The intensity of (020) Bragg peak of β-crystals decreases at a similar rate in both D30 and D100 but disappears at a relatively lower temperature in D30. On the other hand, the β(110) peak intensity of β-PBA crystals formed in the D100 template decreases first at slower rate before α crystals appear, and then at a faster rate once the β to α phase transition takes place. PMID:27008378

  10. The effect of growth rate, diameter and impurity concentration on structure in Czochralski silicon crystal growth

    NASA Technical Reports Server (NTRS)

    Digges, T. G., Jr.; Shima, R.

    1980-01-01

    It is demonstrated that maximum growth rates of up to 80% of the theoretical limit can be attained in Czochralski-grown silicon crystals while maintaining single crystal structure. Attaining the other 20% increase is dependent on design changes in the grower, to reduce the temperature gradient in the liquid while increasing the gradient in the solid. The conclusions of Hopkins et al. (1977) on the effect of diameter on the breakdown of structure at fast growth rates are substantiated. Copper was utilized as the test impurity. At large diameters (greater than 7.5 cm), concentrations of greater than 1 ppm copper were attained in the solid (45,000 ppm in the liquid) without breakdown at maximum growth speeds. For smaller diameter crystals, the sensitivity of impurities is much more apparent. For solar cell applications, impurities will limit cell performance before they cause crystal breakdown for fast growth rates of large diameter crystals.

  11. Growth of Crack-Free 3-Inch-Diameter Lithium Tetraborate Single Crystals by Czochralski Method

    NASA Astrophysics Data System (ADS)

    Komatsu, Ryuichi; Sugihara, Tadashi; Uda, Satoshi

    1994-09-01

    The growth of crack-free 3-inch-diameter lithium tetraborate ( Li2B4O7) single crystals by the Czochralski method has been studied. The relationships between crystal cracking rate during growth and the crystal rotation rate and the position of the work-coil have been examined. It is concluded that crystal cracking at a later stage of growth is related to the temperature fluctuation in melt.

  12. Altimeter error sources at the 10-cm performance level

    NASA Technical Reports Server (NTRS)

    Martin, C. F.

    1977-01-01

    Error sources affecting the calibration and operational use of a 10 cm altimeter are examined to determine the magnitudes of current errors and the investigations necessary to reduce them to acceptable bounds. Errors considered include those affecting operational data pre-processing, and those affecting altitude bias determination, with error budgets developed for both. The most significant error sources affecting pre-processing are bias calibration, propagation corrections for the ionosphere, and measurement noise. No ionospheric models are currently validated at the required 10-25% accuracy level. The optimum smoothing to reduce the effects of measurement noise is investigated and found to be on the order of one second, based on the TASC model of geoid undulations. The 10 cm calibrations are found to be feasible only through the use of altimeter passes that are very high elevation for a tracking station which tracks very close to the time of altimeter track, such as a high elevation pass across the island of Bermuda. By far the largest error source, based on the current state-of-the-art, is the location of the island tracking station relative to mean sea level in the surrounding ocean areas.

  13. Ionization Measurements of SuperCDMS SNOLAB 100 mm Diameter Germanium Crystals

    SciTech Connect

    Chagani, H.; Bauer, D.A.; Brandt, D.; Brink, P.L.; Cabrera, B.; Cherry, M.; Silva, E.Do Couto e; Godfrey, G.G.; Hall, J.; Hansen, S.; Hasi, J.; Kelsey, M.; Kenney, C.J.; Mandic, V.; Nagasawa, D.; Novak, L.; Mirabolfathi, N.; Partridge, R.; Radpour, R.; Resch, R.; Sadoulet, B.; /UC, Berkeley /Stanford U. /SLAC /Stanford U. /Santa Clara U. /Minnesota U.

    2012-06-12

    Scaling cryogenic Germanium-based dark matter detectors to probe smaller WIMP-nucleon cross-sections poses significant challenges in the forms of increased labor, cold hardware, warm electronics and heat load. The development of larger crystals alleviates these issues. The results of ionization tests with two 100 mm diameter, 33 mm thick cylindrical detector-grade Germanium crystals are presented here. Through these results the potential of using such crystals in the Super Cryogenic Dark Matter Search (SuperCDMS) SNOLAB experiment is demonstrated.

  14. Evaluation of Argonne 9-cm and 10-cm Annular Centrifugal Contactors for SHINE Solution Processing

    SciTech Connect

    Wardle, Kent E.; Pereira, Candido; Vandegrift, George

    2015-02-01

    Work is in progress to evaluate the SHINE Medical Technologies process for producing Mo-99 for medical use from the fission of dissolved low-enriched uranium (LEU). This report addresses the use of Argonne annular centrifugal contactors for periodic treatment of the process solution. In a letter report from FY 2013, Pereira and Vandegrift compared the throughput and physical footprint for the two contactor options available from CINC Industries: the V-02 and V-05, which have rotor diameters of 5 cm and 12.7 cm, respectively. They suggested that an intermediately sized “Goldilocks” contactor might provide a better balance between throughput and footprint to meet the processing needs for the uranium extraction (UREX) processing of the SHINE solution to remove undesired fission products. Included with the submission of this letter report are the assembly drawings for two Argonne-design contactors that are in this intermediate range—9-cm and 10-cm rotors, respectively. The 9-cm contactor (drawing number CE-D6973A, stamped February 15, 1978) was designed as a single-stage unit and built and tested in the late 1970s along with other size units, both smaller and larger. In subsequent years, a significant effort to developed annular centrifugal contactors was undertaken to support work at Hanford implementing the transuranic extraction (TRUEX) process. These contactors had a 10-cm rotor diameter and were fully designed as multistage units with four stages per assembly (drawing number CMT-E1104, stamped March 14, 1990). From a technology readiness perspective, these 10-cm units are much farther ahead in the design progression and, therefore, would require significantly less re-working to make them ready for UREX deployment. Additionally, the overall maximum throughput of ~12 L/min is similar to that of the 9-cm unit (10 L/min), and the former could be efficiently operated over much of the same range of throughput. As a result, only the 10-cm units are considered here

  15. Mechanical annealing and source-limited deformation in submicrometre-diameter Ni crystals.

    PubMed

    Shan, Z W; Mishra, Raja K; Syed Asif, S A; Warren, Oden L; Minor, Andrew M

    2008-02-01

    The fundamental processes that govern plasticity and determine strength in crystalline materials at small length scales have been studied for over fifty years. Recent studies of single-crystal metallic pillars with diameters of a few tens of micrometres or less have clearly demonstrated that the strengths of these pillars increase as their diameters decrease, leading to attempts to augment existing ideas about pronounced size effects with new models and simulations. Through in situ nanocompression experiments inside a transmission electron microscope we can directly observe the deformation of these pillar structures and correlate the measured stress values with discrete plastic events. Our experiments show that submicrometre nickel crystals microfabricated into pillar structures contain a high density of initial defects after processing but can be made dislocation free by applying purely mechanical stress. This phenomenon, termed 'mechanical annealing', leads to clear evidence of source-limited deformation where atypical hardening occurs through the progressive activation and exhaustion of dislocation sources. PMID:18157134

  16. 77 FR 32975 - AHRQ Workgroups on ICD-10-CM/PCS Conversion of Quality Indicators (QIs)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-04

    ... HUMAN SERVICES Agency for Healthcare Research and Quality AHRQ Workgroups on ICD-10-CM/PCS Conversion of...-10-CM/PCS, incorporating coding expertise, clinical expertise, and health services research/quality... individuals with relevant clinical expertise (e.g., cardiovascular disease, neurologic disease, orthopedic...

  17. Growth of 3-Inch-Diameter Li2B4O7 Single Crystal Using the Resistance Heating Furnace

    NASA Astrophysics Data System (ADS)

    Sugawara, Tamotsu; Komatsu, Ryuichi; Sugihara, Tadashi

    1994-09-01

    The mode and origin of cracking of lithium tetraborate ( Li2B4O7) single crystals during growth using a resistance heating furnace have been studied. The relationship between the formation mechanism of anomalous growth ridges and the occurrence of cracking was examined. It is concluded that a high temperature gradient near the interface and small temperature fluctuations in the melt are needed for growing a crack-free 3-inch-diameter Li2B4O7 single crystal.

  18. Preparing for ICD-10-CM/PCS implementation: impact on productivity and quality.

    PubMed

    Stanfill, Mary H; Hsieh, Kang Lin; Beal, Kathleen; Fenton, Susan H

    2014-01-01

    Coding productivity is expected to drop significantly during the lead-up to and in the initial stages of ICD-10-CM/PCS implementation, now expected to be delayed until October 1, 2015. This study examined the differences in coding productivity between ICD-9-CM and ICD-10-CM/PCS for hospital inpatient cases matched for complexity and severity. Additionally, interrater reliability was calculated to determine the quality of the coding. On average, coding of an inpatient record took 17.71 minutes (69 percent) longer with ICD-10-CM/PCS than with ICD-9-CM. A two-tailed T-test for statistical validity for independent samples was significant (p = .001). No coder characteristics such as years of experience or educational level were found to be a significant factor in coder productivity. Coders who had received more extensive training were faster than coders who had received only basic training. Though this difference was not statistically significant, it provides a strong indication of significant return on investment for staff training time. Coder interrater reliability was substantial for ICD-9-CM but only moderate for ICD-10-CM/PCS, though some ICD-10-CM/PCS cases had complete interrater (coder) agreement. Time spent coding a case was negatively correlated with interrater reliability (-0.425 for ICD-10-CM and -0.349 for ICD-10-PCS). This finding signals that increased time per case does not necessarily translate to higher quality. Adequate training for coders, as well as guidance regarding time invested per record, is important. Additionally, these findings indicate that previous estimates of initial coder productivity loss with ICD-10-CM/PCS may have been understated. PMID:25214823

  19. Results from the Veterans Health Administration ICD-10-CM/PCS Coding Pilot Study.

    PubMed

    Weems, Shelley; Heller, Pamela; Fenton, Susan H

    2015-01-01

    The Veterans Health Administration (VHA) of the US Department of Veterans Affairs has been preparing for the October 1, 2015, conversion to the International Classification of Diseases, Tenth Revision, Clinical Modification and Procedural Coding System (ICD-10-CM/PCS) for more than four years. The VHA's Office of Informatics and Analytics ICD-10 Program Management Office established an ICD-10 Learning Lab to explore expected operational challenges. This study was conducted to determine the effects of the classification system conversion on coding productivity. ICD codes are integral to VHA business processes and are used for purposes such as clinical studies, performance measurement, workload capture, cost determination, Veterans Equitable Resource Allocation (VERA) determination, morbidity and mortality classification, indexing of hospital records by disease and operations, data storage and retrieval, research purposes, and reimbursement. The data collection for this study occurred in multiple VHA sites across several months using standardized methods. It is commonly accepted that coding productivity will decrease with the implementation of ICD-10-CM/PCS. The findings of this study suggest that the decrease will be more significant for inpatient coding productivity (64.5 percent productivity decrease) than for ambulatory care coding productivity (6.7 percent productivity decrease). This study reveals the following important points regarding ICD-10-CM/PCS coding productivity: 1. Ambulatory care ICD-10-CM coding productivity is not expected to decrease as significantly as inpatient ICD-10-CM/PCS coding productivity. 2. Coder training and type of record (inpatient versus outpatient) affect coding productivity. 3. Inpatient coding productivity is decreased when a procedure requiring ICD-10-PCS coding is present. It is highly recommended that organizations perform their own analyses to determine the effects of ICD-10-CM/PCS implementation on coding productivity. PMID

  20. Challenges and remediation for Patient Safety Indicators in the transition to ICD-10-CM

    PubMed Central

    Boyd, Andrew D; Yang, Young Min; Li, Jianrong; Kenost, Colleen; Burton, Mike D; Becker, Bryan; Lussier, Yves A

    2015-01-01

    Reporting of hospital adverse events relies on Patient Safety Indicators (PSIs) using International Classification of Diseases, Ninth Edition, Clinical Modification (ICD-9-CM) codes. The US transition to ICD-10-CM in 2015 could result in erroneous comparisons of PSIs. Using the General Equivalent Mappings (GEMs), we compared the accuracy of ICD-9-CM coded PSIs against recommended ICD-10-CM codes from the Centers for Medicaid/Medicare Services (CMS). We further predict their impact in a cohort of 38 644 patients (1 446 581 visits and 399 hospitals). We compared the predicted results to the published PSI related ICD-10-CM diagnosis codes. We provide the first report of substantial hospital safety reporting errors with five direct comparisons from the 23 types of PSIs (transfusion and anesthesia related PSIs). One PSI was excluded from the comparison between code sets due to reorganization, while 15 additional PSIs were inaccurate to a lesser degree due to the complexity of the coding translation. The ICD-10-CM translations proposed by CMS pose impending risks for (1) comparing safety incidents, (2) inflating the number of PSIs, and (3) increasing the variability of calculations attributable to the abundance of coding system translations. Ethical organizations addressing ‘data-, process-, and system-focused’ improvements could be penalized using the new ICD-10-CM Agency for Healthcare Research and Quality PSIs because of apparent increases in PSIs bearing the same PSI identifier and label, yet calculated differently. Here we investigate which PSIs would reliably transition between ICD-9-CM and ICD-10-CM, and those at risk of under-reporting and over-reporting adverse events while the frequency of these adverse events remain unchanged. PMID:25186492

  1. Results from the Veterans Health Administration ICD-10-CM/PCS Coding Pilot Study

    PubMed Central

    Weems, Shelley; Heller, Pamela; Fenton, Susan H.

    2015-01-01

    The Veterans Health Administration (VHA) of the US Department of Veterans Affairs has been preparing for the October 1, 2015, conversion to the International Classification of Diseases, Tenth Revision, Clinical Modification and Procedural Coding System (ICD-10-CM/PCS) for more than four years. The VHA's Office of Informatics and Analytics ICD-10 Program Management Office established an ICD-10 Learning Lab to explore expected operational challenges. This study was conducted to determine the effects of the classification system conversion on coding productivity. ICD codes are integral to VHA business processes and are used for purposes such as clinical studies, performance measurement, workload capture, cost determination, Veterans Equitable Resource Allocation (VERA) determination, morbidity and mortality classification, indexing of hospital records by disease and operations, data storage and retrieval, research purposes, and reimbursement. The data collection for this study occurred in multiple VHA sites across several months using standardized methods. It is commonly accepted that coding productivity will decrease with the implementation of ICD-10-CM/PCS. The findings of this study suggest that the decrease will be more significant for inpatient coding productivity (64.5 percent productivity decrease) than for ambulatory care coding productivity (6.7 percent productivity decrease). This study reveals the following important points regarding ICD-10-CM/PCS coding productivity: Ambulatory care ICD-10-CM coding productivity is not expected to decrease as significantly as inpatient ICD-10-CM/PCS coding productivity.Coder training and type of record (inpatient versus outpatient) affect coding productivity.Inpatient coding productivity is decreased when a procedure requiring ICD-10-PCS coding is present. It is highly recommended that organizations perform their own analyses to determine the effects of ICD-10-CM/PCS implementation on coding productivity. PMID:26396553

  2. Mid-continent fall temperatures at the 10-cm soil depth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Recommendations for applying N-fertilizer in autumn involve delaying applications until daily soil temperature at 10 cm depth is = or < 10° C. Daily soil temperature data during autumn were examined from 26 sites along a transect from 36° to 49° N latitude in the mid-continent USA. After soils first...

  3. Physicians’ Outlook on ICD-10-CM/PCS and Its Effect on Their Practice

    PubMed Central

    Watzlaf, Valerie; Alkarwi, Zahraa; Meyers, Sandy; Sheridan, Patty

    2015-01-01

    Background The United States is one of the last countries to change from ICD-9-CM to ICD-10-CM/PCS. The compliance date for implementation of ICD-10-CM/PCS is expected to fall on October 1, 2015. Objectives Evaluate physicians’ perceptions on the change from ICD-9-CM to ICD-10-CM/PCS and its effect on their practice, determine how HIM professionals can assist in this transition, and assess what resources are needed to aid in the transition. Results Twenty physicians were asked to participate in one of three focus groups. Twelve physicians (60 percent) agreed to participate. Top concerns included electronic health record software readiness, increase in documentation specificity and time, ability of healthcare professionals to learn a new language, and inadequacy of current training methods and content. Conclusion Physicians expressed that advantages of ICD-10-CM/PCS were effective data analytics and complexity of patient cases with more specific codes. Health information management professionals were touted as needed during the transition to create simple, clear specialty guides and crosswalks as well as education and training tools specific for physicians. PMID:26807074

  4. Lessons Learned from an ICD-10-CM Clinical Documentation Pilot Study

    PubMed Central

    Moczygemba, Jackie; Fenton, Susan H

    2012-01-01

    On October 1, 2013, the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) will be mandated for use in the United States in place of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). This new classification system will used throughout the nation's healthcare system for recording diagnoses or the reasons for treatment or care. A pilot study was conducted to determine whether current levels of inpatient clinical documentation provide the detail necessary to fully utilize the ICD-10-CM classification system for heart disease, pneumonia, and diabetes cases. The design of this pilot study was cross-sectional. Four hundred ninety-one de-identified records from two sources were coded using ICD-10-CM guidelines and codebooks. The findings of this study indicate that healthcare organizations need to assess clinical documentation and identify gaps. In addition, coder proficiency should be assessed prior to ICD-10-CM implementation to determine the need for further education and training in the biomedical sciences, along with training in the new classification system. PMID:22548021

  5. Survival Strategies for Tsunami of ICD-10-CM for Interventionalists: Pursue or Perish!

    PubMed

    Manchikanti, Laxmaiah; Hammer, Marvel J; Boswell, Mark V; Kaye, Alan D; Hirsch, Joshua A

    2015-01-01

    The unfunded mandate for the implementation of International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) is scheduled October 1, 2015. The development of ICD-10-CM has been a complicated process. We have endeavored to keep Interventional Pain Management doctors apprised via a variety of related topical manuscripts. The major issues relate to the lack of formal physician participation in its preparation. While the American Health Information Management Association (AHIMA) and American Hospital Association (AHA) as active partners in its preparation. Centers for Medicare and Medicaid Services (CMS) and Centers for Disease Control and Prevention (CDC) are major players; 3M and Blue Cross Blue Shield Association are also involved. The cost of ICD-10-CM implementation is high, similar to the implementation of electronic health records (EHRs), likely consuming substantial resources. While ICD-10, utilized worldwide, includes 14,400 different codes, ICD-10-CM, specific for the United States, has expanded to 144,000 codes, which also includes procedural coding system. It is imperative for physicians to prepare for the mandatory implementation. Conversion from ICD-9-CM to ICD-10-CM coding in interventional pain management is not a conversion of one to one that can be easily obtained from software packages. It is a both a difficult and time-consuming task with each physician, early on, expected to spend on estimation at least 10 minutes per visit on extra coding for established and new patients. For interventional pain physicians, there have been a multitude of changes, including creation of new codes and confusing conversion of existing codes. This manuscript describes a variety of codes that are relevant to interventional pain physicians and often utilized in daily practices. It is our objective that this manuscript will provide coding assistance to interventional pain physicians. PMID:26431128

  6. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters.

    PubMed

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-18

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm. PMID:25627639

  7. Crystallization and fusion behaviors, observed by adiabatic calorimetry, of benzene confined in silica mesopores with uniform diameters

    NASA Astrophysics Data System (ADS)

    Nagoe, Atsushi; Oguni, Masaharu; Fujimori, Hiroki

    2015-03-01

    Heat capacities and spontaneous enthalpy-relaxation effects of the benzene confined in silica MCM-41 and SBA-15 pores with uniform diameters were measured by high-precision adiabatic calorimetry. The fusion temperatures and fusion enthalpies determined were compared with the literature results of benzene confined within pores of CPG glasses. It was confirmed, from the observed spontaneous heat-release or -absorption effects, that there exists a non-crystallizing amorphous component of confined benzene, as reported previously. The pore-diameter dependence of fusion enthalpy observed was inconsistent with the previously proposed model which suggested that the non-crystallizing amorphous component is located on the pore wall in the form of a shell-like structure of a few nm in thickness. A very slow relaxation process corresponding to a translational-diffusion motion of molecule was observed, indicating that the benzene fills the pores incompletely along the pore channel. In addition, we found that the fusion enthalpy as a function of inverse pore-diameter dependence decreases steeply in the range of 60-10 nm in diameter while gradually in the range around 5 nm.

  8. ICD-10-CM/PCS: Transferring Knowledge from ICD-9-CM

    PubMed Central

    Sand, Jaime N.; Elison-Bowers, Patt

    2013-01-01

    The transition to ICD-10-CM/PCS has expanded educational opportunities for educators and trainers who are taking on the responsibility of training coders on the new system. Coding education currently faces multiple challenges in the areas of how to train the new workforce, what might be the most efficient method of providing that training, how much retraining of the current workforce with ICD-9-CM training will be required, and how to meet the national implementation deadline of 2014 in the most efficacious manner. This research sought to identify if there was a difference between a group of participants with no knowledge of ICD-9-CM and those with some knowledge of ICD-9-CM in scores on an ICD-10-CM/PCS quiz. Results indicate a difference, supporting the idea of knowledge transfer between the systems and providing additional insight into coding education. PMID:23861677

  9. A Seamless Navigation to ICD-10-CM for Interventional Pain Physicians: Is a Rude Awakening Avoidable?

    PubMed

    Manchikanti, Laxmaiah; Hammer, Marvel; Boswell, Mark V; Kaye, Alan D; Hirsch, Joshua A

    2016-01-01

    Since October 1, 2015, the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) was integrated into U.S. medical practices. This monumental transition seemingly occurred rather unceremoniously, despite significant opposition and reservations having been expressed by the provider community. In prior publications, we have described various survival strategies for interventional pain physicians. The regulators and beneficiaries of system-CMS, consultants, and health information technology industry are congratulating themselves for a job well done. Nonetheless, this transition comes at an immeasurable financial and psychological drain on providers. However, a rude awakening may be making its way with expiration of initial concessions from government and private payers.This manuscript provides a template for interventional pain management professionals with multiple steps for seamless navigation, including descriptions of the most commonly used codes, navigation through ICD-10-CM manual, steps for correct coding, and finally, detailed coding descriptions for various interventional techniques. PMID:26752478

  10. Adapting a Clinical Data Repository to ICD-10-CM through the use of a Terminology Repository.

    PubMed

    Cimino, James J; Remennick, Lyubov

    2014-01-01

    Clinical data repositories frequently contain patient diagnoses coded with the International Classification of Diseases, Ninth Revision (ICD-9-CM). These repositories now need to accommodate data coded with the Tenth Revision (ICD-10-CM). Database users wish to retrieve relevant data regardless of the system by which they are coded. We demonstrate how a terminology repository (the Research Entities Dictionary or RED) serves as an ontology relating terms of both ICD versions to each other to support seamless version-independent retrieval from the Biomedical Translational Research Information System (BTRIS) at the National Institutes of Health. We make use of the Center for Medicare and Medicaid Services' General Equivalence Mappings (GEMs) to reduce the modeling effort required to determine whether ICD-10-CM terms should be added to the RED as new concepts or as synonyms of existing concepts. A divide-and-conquer approach is used to develop integration heuristics that offer a satisfactory interim solution and facilitate additional refinement of the integration as time and resources allow. PMID:25954344

  11. Effective dose equivalent for point gamma sources located 10 cm near the body.

    PubMed

    Xu, X George; Bushart, Sean; Anderson, Ralph

    2006-08-01

    The key component in the so-called EPRI effective dose equivalent (EDE) methodology is an algorithm that utilizes two dosimeters (instead of multiple dosimeters) to predict the EDE for external photon exposures. The exposure scenarios that were previously studied in deriving the algorithm include parallel photon beams and point sources 33 cm from the body surface. The motivation for this study was the need to investigate source locations within 33 cm from the body so the method is more widely applicable. The ORNL stylized mathematical human phantoms and the MCNP code were used to calculate organ doses in this study. This paper presents the EDE data for point gamma sources at 0.3, 1.0, and 1.5 MeV, respectively, which are located at 10 cm from the surface of the body. The results and analyses show that the locations ranging from the overhead to the foot have resulted in conservative ratios except for two general regions near the front upper thigh and directly overhead. If all locations considered in this study were averaged for each photon energy, the overall ratio is on the conservative side. These data suggest that the EPRI EDE methodology is still valid for sources located 10 cm from the body, although the chance for resulting in a non-conservative estimate of the EDE has increased in comparison with the sources located at 30 cm from the body. Finally, this paper provides recommendations on how to apply the EPRI EDE methodology. PMID:16832191

  12. Organic blend semiconductors and transistors with hole mobility exceeding 10 cm2/Vs (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Paterson, Alexandra F.; Anthopoulos, Thomas D.

    2015-10-01

    Plastic electronics that can be manufactured using solution-based methods are the subject of great research interest due to their potential for low-cost, large-area electronic applications. The interest in this field has led to considerable research and subsequent advances in device performance. To this end solution-processed organic thin-film transistors (OTFTs) have shown impressive improvements in recent years through the increasing values of charge carrier mobility. Here we report the development of next generation organic blend materials for OTFTs with hole mobilities of 10 cm2/Vs. These high performance devices have been achieved using a novel semiconducting blend system comprising of an amorphous-like conjugated polymer and a high mobility small molecule. The combination of a highly crystalline small molecule with the polymer binder aids the formation of uniform films as well as enables an element of control over the nucleation and growth of the small molecule. The polymer binders investigated belongs to the family of indacenodithiophene-based copolymers which are renowned for their high carrier mobilities regardless of their apparent structural disorder. The addition of the polymer with carefully chosen small molecules is found to further increase the hole mobility of the resulting blend OTFT to over 10 cm2/Vs. These organic devices provide an interesting insight into this rather complex blend system, highlighting the correlation between the morphology developed following solution processing and device performance, as well as exploring the role of each of the two components in the blend in terms of their contribution to charge transport.

  13. Estimation of CO2 diffusion coefficient at 0-10 cm depth in undisturbed and tilled soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diffusion coefficients (D) of CO2 at 0 – 10 cm layers in undisturbed and tilled soil conditions were estimated using Penman, Millington-Quirk, Ridgwell et al. (1999), Troeh et al., and Moldrup et al. models. Soil bulk density and volumetric soil water content ('v) at 0 – 10 cm were measured on April...

  14. Assessing the planning and implementation strategies for the ICD-10-CM/PCS coding transition in Alabama hospitals.

    PubMed

    Houser, Shannon H; Morgan, Darius; Clements, Kay; Hart-Hester, Susan

    2013-01-01

    Health information management (HIM) professionals play a significant role in transitioning from ICD-9-CM to ICD-10-CM/PCS. ICD-10-CM/PCS coding will impact many operational aspects of healthcare facilities, such as physicians' documentation in health records, coders' process for review of clinical information, the billing process, and the payers' reimbursement to the healthcare facilities. This article examines the level of readiness and planning for ICD-10-CM/PCS implementation among hospitals in Alabama, identifies training methods/approaches to be used by the hospitals, and discusses the challenges to the ICD-10-CM/PCS coding transition. A 16-question survey was distributed to 116 Alabama hospital HIM directors in December 2011 with follow-up through February 2012. Fifty-three percent of respondent hospitals began the planning process in 2011, and most facilities were halfway or less than halfway to completion of specific implementation tasks. Hospital coders will be or are being trained using in-house training, through seminars/webinars, or by consultants. The impact of ICD-10-CM/PCS implementation can be minimized by training coders in advance, hiring new coders, and adjusting coders' productivity measures. Three major challenges to the transition were identified: the need to interact with physicians and other providers more often to obtain information needed to code in ICD-10-CM/PCS systems, education and training of coders and other ICD-10-CM/PCS users, and dependence on vendors for major technology upgrades for ICD-10-CM/PCS systems. Survey results provide beneficial information for HIM professionals and other users of coded data to assist in establishing sound practice standards for ICD-10-CM/PCS coding implementation. Adequate planning and preparation will be essential to the successful implementation of ICD-10-CM/PCS. PMID:23805061

  15. 77 FR 40620 - AHRQ Workgroups on ICD-10-CM/PCS Conversion of Quality Indicators (QIs) - Extension Date for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-10

    ... HUMAN SERVICES Agency for Healthcare Research and Quality AHRQ Workgroups on ICD-10-CM/PCS Conversion of... expertise, and health services research/quality measurement expertise. The workgroups will evaluate the... notice was previously published on June 4, 2012 (...

  16. A Comparison between a SNOMED CT Problem List and the ICD-10-CM/PCS HIPAA Code Sets

    PubMed Central

    Steindel, Steven J

    2012-01-01

    In 2013 the United States will convert from the use of the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) to the use of the International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS). This study compares the approximately 5,000 terms in the July 2009 Clinical Observations Recording and Encoding (CORE) Problem List subset of the Systematized Nomenclature of Medicine–Clinical Terms (SNOMED CT) terminology produced by the National Library of Medicine with terms found in the January 2009 versions of ICD-10-CM/PCS. The comparison was done by a single individual and used the internally defined concepts of “Exact,” “Inexact,” “Model” (one SNOMED CT term to many ICD-10-CM/PCS terms), “Not Elsewhere Classified,” “Not Otherwise Specified,” “Synonym,” and “Not Found” to classify the CORE Problem List terms according to the quality of the match. Among the CORE Problem List terms, 6.0 percent were not found in ICD-10-CM/PCS, and 69.1 percent had equivalent ICD-10-CM/PCS terms. The 13.0 percent of terms classified as “Inexact” could also be used directly assuming some acceptable loss of clinical precision. The 11.9 percent of terms classified as “Model” represent differences that require rule-based mapping. The results of this study suggest that ICD-10-CM/PCS meets the intended design goal of increased clinical precision but studies are needed to precisely define the depth of coverage. PMID:22548020

  17. Light propagation characteristics in photonic crystal fibers with α-power profiles of air hole diameter distributions and their application to fiber collimator

    NASA Astrophysics Data System (ADS)

    Yokota, Hirohisa; Higuchi, Keiichi; Imai, Yoh

    2016-08-01

    Light propagation characteristics in photonic crystal fibers (PCFs) with α-power profiles of air hole diameter distributions were theoretically investigated. It was clarified that the intensity peak of the beam propagating in the PCF with Gaussian beam excitation varied periodically with little power attenuation. It was found that the envelope of the periodic intensity variation depended on α. We theoretically demonstrated that the PCF with the α-power profile of the air hole diameter distribution could be applied to a collimator for a conventional PCF with uniform air holes in Gaussian beam excitation to reduce coupling loss, where a PCF of appropriate length with the α-power air hole diameter distribution was spliced to a conventional PCF. It was also found that the coupling efficiency was higher for a larger α.

  18. The Complexity and Challenges of the ICD-9-CM to ICD-10-CM Transition in Emergency Departments

    PubMed Central

    Krive, Jacob; Patel, Mahatkumar; Gehm, Lisa; Mackey, Mark; Kulstad, Erik; Li, Jianrong ‘John’; Lussier, Yves A.; Boyd, Andrew D.

    2015-01-01

    Beginning October 2015, the Center for Medicare and Medicaid Services (CMS) will require medical providers to utilize the vastly expanded ICD-10-CM system. Despite wide availability of information and mapping tools for the next generation of the ICD classification system, some of the challenges associated with transition from ICD-9-CM to ICD-10-CM are not well understood. To quantify the challenges faced by emergency physicians, we analyzed a subset of a 2010 Illinois Medicaid database of emergency department ICD-9-CM codes, seeking to determine the accuracy of existing mapping tools in order to better prepare emergency physicians for the change to the expanded ICD-10-CM system. We found that 27% of 1,830 codes represented convoluted multidirectional mappings. We then analyzed the convoluted transitions and found 8% of total visit encounters (23% of the convoluted transitions) were clinically incorrect. The ambiguity and inaccuracy of these mappings may impact the work flow associated with the translation process and affect the potential mapping between ICD codes and CPT (Current Procedural Codes) codes, which determine physician reimbursement. PMID:25863652

  19. Preparing for the ICD-10-CM Transition: Automated Methods for Translating ICD Codes in Clinical Phenotype Definitions

    PubMed Central

    Fung, Kin Wah; Richesson, Rachel; Smerek, Michelle; Pereira, Katherine C.; Green, Beverly B.; Patkar, Ashwin; Clowse, Megan; Bauck, Alan; Bodenreider, Olivier

    2016-01-01

    Background: The national mandate for health systems to transition from ICD-9-CM to ICD-10-CM in October 2015 has an impact on research activities. Clinical phenotypes defined by ICD-9-CM codes need to be converted to ICD-10-CM, which has nearly four times more codes and a very different structure than ICD-9-CM. Methods: We used the Centers for Medicare & Medicaid Services (CMS) General Equivalent Maps (GEMs) to translate, using four different methods, condition-specific ICD-9-CM code sets used for pragmatic trials (n=32) into ICD-10-CM. We calculated the recall, precision, and F score of each method. We also used the ICD-9-CM and ICD-10-CM value sets defined for electronic quality measure as an additional evaluation of the mapping methods. Results: The forward-backward mapping (FBM) method had higher precision, recall and F-score metrics than simple forward mapping (SFM). The more aggressive secondary (SM) and tertiary mapping (TM) methods resulted in higher recall but lower precision. For clinical phenotype definition, FBM was the best (F=0.67), but was close to SM (F=0.62) and TM (F=0.60), judging on the F-scores alone. The overall difference between the four methods was statistically significant (one-way ANOVA, F=5.749, p=0.001). However, pairwise comparisons between FBM, SM, and TM did not reach statistical significance. A similar trend was found for the quality measure value sets. Discussion: The optimal method for using the GEMs depends on the relative importance of recall versus precision for a given use case. It appears that for clinically distinct and homogenous conditions, the recall of FBM is sufficient. The performance of all mapping methods was lower for heterogeneous conditions. Since code sets used for phenotype definition and quality measurement can be very similar, there is a possibility of cross-fertilization between the two activities. Conclusion: Different mapping approaches yield different collections of ICD-10-CM codes. All methods require

  20. Structure optimization of small-diameter polarization-maintaining photonic crystal fiber for mini coil of spaceborne miniature fiber-optic gyroscope.

    PubMed

    Song, Ningfang; Cai, Wei; Song, Jingming; Jin, Jing; Wu, Chunxiao

    2015-11-20

    A small-diameter polarization-maintaining photonic crystal fiber (PM-PCF) for mini coils of spaceborne miniature fiber-optic gyroscopes is proposed in this paper. To ensure the strength of the small-diameter PM-PCF, a four-ring air holes structure is adopted. Using the full vector finite element method, dependence studies of modal field distribution, birefringence, and confinement loss on several key structure parameters are numerically investigated. The optimized parameter region is obtained. An optimized PM-PCF is fabricated, which can achieve similar to or even better optical properties than that of commercial PM-PCFs. The coating and cladding diameters of the optimized PM-PCF are 135 μm and 100 μm, respectively. Meanwhile, the optimized small-diameter PM-PCF shows a proof test level of 0.5%. The attenuation of the PM-PCF at 1550 nm is ∼2  dB/km. Typical volume of a mini coil wound with 300 m optimized PM-PCF is 5.9  cm3, which is decreased by ∼60% compared with a commercial PM-PCF coil of the same length. The bias stability of this coil is comparable with that of a conventional PMF coil of comparable length. Thus, the optimized small-diameter PM-PCF is suitable for mini coils of spaceborne miniature fiber-optic gyroscopes. PMID:26836545

  1. Calorimetric determination of kQ factors for NE 2561 and NE 2571 ionization chambers in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV photons

    NASA Astrophysics Data System (ADS)

    Krauss, Achim; Kapsch, Ralf-Peter

    2007-10-01

    The relative uncertainty of the ionometric determination of the absorbed dose to water, Dw, in the reference dosimetry of high-energy photon beams is in the order of 1.5% and is dominated by the uncertainty of the calculated chamber- and energy-dependent correction factors kQ. In the present investigation, kQ values were determined experimentally in 5 cm × 5 cm and 10 cm × 10 cm radiotherapy beams of 8 MV and 16 MV bremsstrahlung by means of a water calorimeter operated at 4 °C. Ionization chambers of the types NE 2561 and NE 2571 were calibrated directly in the water phantom of the calorimeter. The measurements were carried out at the linear accelerator of the Physikalisch-Technische Bundesanstalt. It is shown that the kQ factor of a single ionization chamber can be measured with a standard uncertainty of less than 0.3%. No significant variations of kQ were found for the different lateral sizes of the radiation fields used in this investigation.

  2. A case study demonstration of the soil temperature extrema recovery rates after precipitation cooling at 10-cm soil depth

    NASA Technical Reports Server (NTRS)

    Welker, Jean Edward

    1991-01-01

    Since the invention of maximum and minimum thermometers in the 18th century, diurnal temperature extrema have been taken for air worldwide. At some stations, these extrema temperatures were collected at various soil depths also, and the behavior of these temperatures at a 10-cm depth at the Tifton Experimental Station in Georgia is presented. After a precipitation cooling event, the diurnal temperature maxima drop to a minimum value and then start a recovery to higher values (similar to thermal inertia). This recovery represents a measure of response to heating as a function of soil moisture and soil property. Eight different curves were fitted to a wide variety of data sets for different stations and years, and both power and exponential curves were fitted to a wide variety of data sets for different stations and years. Both power and exponential curve fits were consistently found to be statistically accurate least-square fit representations of the raw data recovery values. The predictive procedures used here were multivariate regression analyses, which are applicable to soils at a variety of depths besides the 10-cm depth presented.

  3. Characterization of 100 mm diameter 4H-silicon carbide crystals with extremely low basal plane dislocation density

    SciTech Connect

    Dudley, M.; Zhang, N; Zhang, Y; Raghothamachar, B; Byrappa, S; Choi, G; Sanchez, E; Hansen, D; Drachev, R; Loboda, M

    2010-01-01

    Synchrotron White Beam X-ray Topography (SWBXT) studies are presented of basal plane dislocation (BPD) configurations and behavior in a new generation of 100mm diameter, 4H-SiC wafers with extremely low BPD densities (3-4 x 10{sup 2} cm{sup -2}). The conversion of non-screw oriented, glissile BPDs into sessile threading edge dislocations (TEDs) is observed to provide pinning points for the operation of single ended Frank-Read sources. In some regions, once converted TEDs are observed to re-convert back into BPDs in a repetitive process which provides multiple BPD pinning points.

  4. Characterization of 100 mm Diameter 4H-Silicon Carbide CrystalsWith Extremely Low Basal Plane Dislocation Density

    SciTech Connect

    M Dudley; N Zhang; Y Zhang; B Raghothamachar; S Byrappa; G Choi; E Drachev; M Loboda

    2011-12-31

    Synchrotron White Beam X-ray Topography (SWBXT) studies are presented of basal plane dislocation (BPD) configurations and behavior in a new generation of 100mm diameter, 4H-SiC wafers with extremely low BPD densities (3-4 x 10{sup 2} cm{sup -2}). The conversion of non-screw oriented, glissile BPDs into sessile threading edge dislocations (TEDs) is observed to provide pinning points for the operation of single ended Frank-Read sources. In some regions, once converted TEDs are observed to re-convert back into BPDs in a repetitive process which provides multiple BPD pinning points.

  5. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate

    PubMed Central

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the “V”-shaped or “U”-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  6. Ordered array of Ag semishells on different diameter monolayer polystyrene colloidal crystals: An ultrasensitive and reproducible SERS substrate.

    PubMed

    Yi, Zao; Niu, Gao; Luo, Jiangshan; Kang, Xiaoli; Yao, Weitang; Zhang, Weibin; Yi, Yougen; Yi, Yong; Ye, Xin; Duan, Tao; Tang, Yongjian

    2016-01-01

    Ag semishells (AgSS) ordered arrays for surface-enhanced Raman scattering (SERS) spectroscopy have been prepared by depositing Ag film onto polystyrene colloidal particle (PSCP) monolayer templates array. The diversified activity for SERS activity with the ordered AgSS arrays mainly depends on the PSCP diameter and Ag film thickness. The high SERS sensitivity and reproducibility are proved by the detection of rhodamine 6G (R6G) and 4-aminothiophenol (4-ATP) molecules. The prominent enhancements of SERS are mainly from the "V"-shaped or "U"-shaped nanogaps on AgSS, which are experimentally and theoretically investigated. The higher SERS activity, stability and reproducibility make the ordered AgSS a promising choice for practical SERS low concentration detection applications. PMID:27586562

  7. The road to ICD-10-CM/PCS implementation: forecasting the transition for providers, payers, and other healthcare organizations.

    PubMed

    Sanders, Tekla B; Bowens, Felicia M; Pierce, William; Stasher-Booker, Bridgette; Thompson, Erica Q; Jones, Warren A

    2012-01-01

    This article will examine the benefits and challenges of the US healthcare system's upcoming conversion to use of the International Classification of Diseases, Tenth Revision, Clinical Modification/Procedure Coding System (ICD-10-CM/PCS) and will review the cost implications of the transition. Benefits including improved quality of care, potential cost savings from increased accuracy of payments and reduction of unpaid claims, and improved tracking of healthcare data related to public health and bioterrorism events are discussed. Challenges are noted in the areas of planning and implementation, the financial cost of the transition, a shortage of qualified coders, the need for further training and education of the healthcare workforce, and the loss of productivity during the transition. Although the transition will require substantial implementation and conversion costs, potential benefits can be achieved in the areas of data integrity, fraud detection, enhanced cost analysis capabilities, and improved monitoring of patients' health outcomes that will yield greater cost savings over time. The discussion concludes with recommendations to healthcare organizations of ways in which technological advances and workforce training and development opportunities can ease the transition to the new coding system. PMID:22548024

  8. In-situ determination of astro-comb calibrator lines to better than 10 cm s(-1).

    PubMed

    Li, Chih-Hao; Glenday, Alexander G; Benedick, Andrew J; Chang, Guoqing; Chen, Li-Jin; Cramer, Claire; Fendel, Peter; Furesz, Gabor; Kärtner, Franz X; Korzennik, Sylvain; Phillips, David F; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L

    2010-06-01

    Improved wavelength calibrators for high-resolution astrophysical spectrographs will be essential for precision radial velocity (RV) detection of Earth-like exoplanets and direct observation of cosmological deceleration. The astro-comb is a combination of an octave-spanning femtosecond laser frequency comb and a Fabry-Pérot cavity used to achieve calibrator line spacings that can be resolved by an astrophysical spectrograph. Systematic spectral shifts associated with the cavity can be 0.1-1 MHz, corresponding to RV errors of 10-100 cm/s, due to the dispersive properties of the cavity mirrors over broad spectral widths. Although these systematic shifts are very stable, their correction is crucial to high accuracy astrophysical spectroscopy. Here, we demonstrate an in-situ technique to determine the systematic shifts of astro-comb lines due to finite Fabry-Pérot cavity dispersion. The technique is practical for implementation at a telescope-based spectrograph to enable wavelength calibration accuracy better than 10 cm/s. PMID:20588453

  9. DORIS/Jason-2: Better than 10 cm on-board orbits available for Near-Real-Time Altimetry

    NASA Astrophysics Data System (ADS)

    Jayles, C.; Chauveau, J. P.; Rozo, F.

    2010-12-01

    DIODE (DORIS Immediate Orbit on-board Determination) is a real-time on-board orbit determination software, embedded in the DORIS receiver. The purpose of this paper is to focus on DIODE performances. After a description of the recent DORIS evolutions, we detail how compliance with specifications are verified during extensive ground tests before the launch, then during the in-flight commissioning phase just after the launch, and how well they are met in the routine phase and today. Future improvements are also discussed for Jason-2 as well as for the next missions. The complete DORIS ground validation using DORIS simulator and new DORIS test equipments has shown prior to the Jason-2 flight that every functional requirement was fulfilled, and also that better than 10 cm real-time DIODE orbits would be achieved on-board Jason-2. The first year of Jason-2 confirmed this, and after correction of a slowly evolving polar motion error at the end of the commissioning phase, the DIODE on-board orbits are indeed better than the 10 cm specification: in the beginning of the routine phase, the discrepancy was already 7.7 cm Root-Mean-Square (RMS) in the radial component as compared to the final Precise Orbit Ephemerides (POE) orbit. Since the first day of Jason-2 cycle 1, the real-time DIODE orbits have been delivered in the altimetry fast delivery products. Their accuracy and their 100% availability make them a key input to fairly precise Near-Real-Time Altimetry processing. Time-tagging is at the microsecond level. In parallel, a few corrections (quaternion problem) and improvements have been gathered in an enhanced version of DIODE, which is already implemented and validated. With this new version, a 5 cm radial accuracy is achieved during ground validation over more than Jason-2 first year (cycles 1-43, from July 12th, 2008 to September 11th, 2009). The Seattle Ocean Surface Topography Science Team Meeting (OSTST) has recommended an upload of this v4.02 version on

  10. ICD-9-CM and ICD-10-CM mapping of the AAST Emergency General Surgery disease severity grading systems: Conceptual approach, limitations, and recommendations for the future.

    PubMed

    Utter, Garth H; Miller, Preston R; Mowery, Nathan T; Tominaga, Gail T; Gunter, Oliver; Osler, Turner M; Ciesla, David J; Agarwal, Suresh K; Inaba, Kenji; Aboutanos, Michel B; Brown, Carlos V R; Ross, Steven E; Crandall, Marie L; Shafi, Shahid

    2015-05-01

    The American Association for the Surgery of Trauma (AAST) recently established a grading system for uniform reporting of anatomic severity of several emergency general surgery (EGS) diseases. There are five grades of severity for each disease, ranging from I (lowest severity) to V (highest severity). However, the grading process requires manual chart review. We sought to evaluate whether International Classification of Diseases, 9th and 10th Revisions, Clinical Modification (ICD-9-CM, ICD-10-CM) codes might allow estimation of AAST grades for EGS diseases. The Patient Assessment and Outcomes Committee of the AAST reviewed all available ICD-9-CM and ICD-10-CM diagnosis codes relevant to 16 EGS diseases with available AAST grades. We then matched grades for each EGS disease with one or more ICD codes. We used the Official Coding Guidelines for ICD-9-CM and ICD-10-CM and the American Hospital Association's "Coding Clinic for ICD-9-CM" for coding guidance. The ICD codes did not allow for matching all five AAST grades of severity for each of the 16 diseases. With ICD-9-CM, six diseases mapped into four categories of severity (instead of five), another six diseases into three categories of severity, and four diseases into only two categories of severity. With ICD-10-CM, five diseases mapped into four categories of severity, seven diseases into three categories, and four diseases into two categories. Two diseases mapped into discontinuous categories of grades (two in ICD-9-CM and one in ICD-10-CM). Although resolution is limited, ICD-9-CM and ICD-10-CM diagnosis codes might have some utility in roughly approximating the severity of the AAST grades in the absence of more precise information. These ICD mappings should be validated and refined before widespread use to characterize EGS disease severity. In the long-term, it may be desirable to develop alternatives to ICD-9-CM and ICD-10-CM codes for routine collection of disease severity characteristics. PMID:25909431

  11. The Tragedy of the Implementation of ICD-10-CM as ICD-10: Is the Cart Before the Horse or Is There a Tragic Paradox of Misinformation and Ignorance?

    PubMed

    Manchikanti, Laxmaiah; Kaye, Alan D; Singh, Vijay; Boswell, Mark V

    2015-01-01

    The forced implementation of ICD-10-CM (International Classification of Diseases, Tenth Revision, Clinical Modification) codes that are specific to the United States, scheduled for implementation October 1, 2015, which is vastly different from ICD-10 (International Classification of Diseases, Tenth Revision), implemented worldwide, which has 14,400 codes, compared to ICD-10-CM with 144,000 codes to be implemented in the United States is a major concern to practicing U.S. physicians and a bonanza for health IT and hospital industry. This implementation is based on a liberal interpretation of the Health Insurance Portability and Accountability Act (HIPAA), which requires an update to ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) and says nothing about ICD-10 or beyond. On June 29, 2015, the Supreme Court ruled that the Environmental Protection Agency unreasonably interpreted the Clean Air Act when it decided to set limits on the emissions of toxic pollutants from power plants, without first considering the costs on the industry. Thus, to do so is applicable to the medical industry with the Centers for Medicare and Medicaid Services (CMS) unreasonably interpreting HIPAA and imposing existent extensive regulations without considering the cost. In the United States, ICD-10-CM with a 10-fold increase in the number of codes has resulted in a system which has become so complicated that it no longer compares with any other country. Moreover, most WHO members use the ICD-10 system (not ICD-10-CM) only to record mortality in 138 countries or morbidity in 99 countries. Currently, only 10 countries employ ICD-10 (not ICD-10-CM) in the reimbursement process, 6 of which have a single payer health care system. Development of ICD-10-CM is managed by 4 non-physician groups, known as cooperating parties. They include the Centers for Disease Control and Prevention (CDC), CMS, the American Hospital Association (AHA), and the American Health

  12. Dynamics of cell and tissue growth acquired by means of 25 mm2 to 10 cm2 lens-free imaging

    NASA Astrophysics Data System (ADS)

    Momey, F.; Coutard, J.-G.; Bordy, T.; Navarro, F.; Menneteau, M.; Dinten, J.-M.; Allier, C.

    2015-03-01

    In this paper, we discuss a new methodology based on lens-free imaging to perform wound healing assay with unprecedented statistics. Our video lens-free microscopy setup is a simple optical system featuring only a CMOS sensor and a semi coherent illumination system. Yet it is a powerful means for the real-time monitoring of cultivated cells. It presents several key advantages, e.g., integration into standard incubator, compatibility with standard cell culture protocol, simplicity and ease of use. It can perform the follow-up in a large field of view (25 mm2) of several crucial parameters during the culture of cells i.e. their motility, their proliferation rate or their death. Consequently the setup can gather large statistics both in space and time. But in the case of tissue growth experiments, the field of view of 25 mm2 remains not sufficient and results can be biased depending on the position of the device with respect to the recipient of the cell culture. Hence, to conduct exhaustive wound healing assay, here we propose to enlarge the field of view up to 10 cm2 through two different approaches. The first method consists in performing a scan of the cell culture by moving the source/sensor couple and then stitch the stack of images. The second is to make an acquisition by scanning with a line scan camera. The two approaches are compared in term of resolution, complexity and acquisition time. Next we have performed acquisitions of wound healing assay (keratinocytes HaCaT) both in real-time (25 mm2) and in final point (10 cm2) to assess the combination of these two complementary modalities. In the future, we aim at combining directly super wide field of view acquisitions (>10 cm2) with real time ability inside the incubator.

  13. Control of coupling in 1D photonic crystal coupled-cavity nano-wire structures via hole diameter and position variation

    NASA Astrophysics Data System (ADS)

    Zain, A. R. Md; De La Rue, R. M.

    2015-12-01

    We have successfully demonstrated close experimental control of the resonance splitting/free spectral range of a coupled micro-cavity one-dimensional photonic crystal/photonic wire device structure based on silicon-on-insulator. Clear splitting of the resonances, with FSR values ranging from 8 nm to 48 nm, was obtained through the use of different hole arrangements within the middle section of the device structures, between the coupled cavities. The results show good agreement with calculations obtained using a finite-difference time-domain simulation approach.

  14. Ultralow-frequency Raman system down to 10 cm(-1) with longpass edge filters and its application to the interface coupling in t(2+2)LGs.

    PubMed

    Lin, M-L; Ran, F-R; Qiao, X-F; Wu, J-B; Shi, W; Zhang, Z-H; Xu, X-Z; Liu, K-H; Li, H; Tan, P-H

    2016-05-01

    Ultralow-frequency (ULF) Raman spectroscopy becomes increasingly important in the area of two-dimensional (2D) layered materials; however, such measurement usually requires expensive and nonstandard equipment. Here, the measurement of ULF Raman signal down to 10 cm(-1) has been realized with high throughput by combining a kind of longpass edge filters with a single monochromator, which are verified by the Raman spectrum of L-cystine using three laser excitations. Fine adjustment of the angle of incident laser beam from normal of the longpass edge filters and selection of polarization geometry are demonstrated how to probe ULF Raman signal with high signal-to-noise. Davydov splitting of the shear mode in twisted (2+2) layer graphenes (t(2+2)LG) has been observed by such system in both exfoliated and transferred samples. We provide a direct evidence of twist-angle dependent softening of the shear coupling in t(2+2)LG, while the layer-breathing coupling at twisted interfaces is found to be almost identical to that in bulk graphite. This suggests that the exfoliation and transferring techniques are enough good to make a good 2D heterostructures to demonstrate potential device application. This Raman system will be potentially applied to the research field of ULF Raman spectroscopy. PMID:27250407

  15. Characterization of dislocation and defects for large high purity Ge crystals

    NASA Astrophysics Data System (ADS)

    Mei, Hao; Wang, Guojian; Guan, Yutong; Yang, Gang; Mei, Dongming; Cubed Collaboration

    2015-03-01

    Large diameter (~10 cm) high purity Germanium (HP-Ge) crystals have been growing via Czochralski method at University of South Dakota. We investigate the impacts of growth rate, time-temperature profile, and thermal gradient on the dislocation and defects distribution in HP-Ge crystals along <100>orientation. The dislocation density across the entire cross-section of a grown crystal is measured using microscope. Utilizing X-Ray Diffraction method, we obtain the rocking curves from the same crystal samples. We analyze the correlation between the full width at half maximum (FWHM) of the rocking curves and the dislocation densities from the optical observations (etch pits distribution). A model that describes the correlation of dislocation density, along the HP-Ge crystal, with the FWHM of the rock curves for XRD is established. We report these analytic results. This work is supported by DOE Grant DE-FG02-10ER46709 and the state of South.

  16. Interpreting stem diameter changes

    NASA Astrophysics Data System (ADS)

    Hölttä, T.; Sevanto, S.; Nikinmaa, E.

    2009-12-01

    Detecting phloem transport in stem diameter changes Teemu Hölttä1, Sanna Sevanto2, Eero Nikinmaa1 1Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland 2Department of Physics, P.O. Box 48, FIN-00014 University of Helsinki, Finland Introduction The volume of living cells and xylem conduits vary according to pressures they are subjected to. Our proposition is that the behavior of the inner bark diameter variation which cannot be explained by changes in xylem water status arise from changes in the osmotic concentration of the phloem and cambial growth. Materials and methods Simultaneous xylem and stem diameter measurements were conducted between June 28th to October 4th 2006 in Southern Finland on a 47-year old, 15 meter tall, Scots pine tree (DBH 15 cm) at heights of 1.5 and 10 meters. The difference between the measured inner bark diameter and the inner bark diameter predicted from xylem diameter change with a simple model (assuming there was no change in the osmotic concentration of the phloem) is hypothesized to give the changes in the osmotic concentration of the inner bark. The simple model calculates the radial water exchange between the xylem and phloem driven by the water potential changes in the xylem. Results and Discussion The major signal in the inner bark diameter was the transpiration rate as assumed, but also a signal arising from the change in the osmotic concentration (Fig 1a). The predicted osmotic concentration of the phloem typically increased during the afternoon due to the loading of photosynthesized sugars to the phloem. Inner bark osmotic concentration followed the photosynthesis rate with a 3 and 4 hour time-lag at the top and base, respectively (Fig 1b). The connection between photosynthesis and the predicted change in phloem osmotic concentration was stronger in the upper part of the tree compared to lower part. The changes in the predicted osmotic concentration were not similar every day, indicating that

  17. Growth of Si Bulk Crystals with Large Diameter Ratio Using Small Crucibles by Creating a Large Low-Temperature Region Inside a Si Melt Contained in an NOC Furnace Developed Using Two Zone Heaters

    NASA Astrophysics Data System (ADS)

    Nakajima, Kazuo; Ono, Satoshi; Murai, Ryota; Kaneko, Yuzuru

    2016-06-01

    Three zone heaters were generally used for a noncontact crucible (NOC) furnace. For practical reasons a simpler NOC furnace was developed with two zone heaters, which had a carbon heat holder to cover the three roles of each heater. Large low-temperature regions were obtained, and silicon ingots were grown in small crucibles with a large diameter and diameter ratio. Here, the diameter ratio is the ratio of the ingot diameter to the crucible diameter and can be as large as 0.90. The diameter ratio was controlled mainly by the temperature reduction of the first heater. Power changes of the second heater did not have a significant impact on the ingot diameter. Using this NOC furnace, maximum ingot diameters of 28.0, 33.5, and 45.0 cm were obtained using crucibles of 33, 40, and 50 cm in diameter, respectively. The oxygen concentration of the ingots did not strongly depend on the diameter ratio and were always low because convection in the Si melt was markedly suppressed by the carbon heat holder. Moreover, the oxygen concentration of the ingots has a tendency to become lower as the crucible diameter becomes larger.

  18. Economics of ingot slicing with an internal diameter saw for low-cost solar cells

    NASA Technical Reports Server (NTRS)

    Daud, T.; Liu, J. K.; Fiegl, G.

    1981-01-01

    Slicing of silicon ingots using diamond impregnated internal diameter blade saws has been a standard technology of the semiconductor industry. This paper describes work on improvements to this technology for 10 cm diameter ingot slicing. Ingot rotation, dynamic blade edge control with feedback, mechanized blade dressing and development of thinner blades are the approaches tried. A comparison of the results for wafering with and without ingot rotation is also made. A sensitivity analysis of the major cost elements in wafering is performed for 10 cm diameter ingot and extended to the 15 cm diameter ingot case. Various parameter values such as machine cost, feed rate and consumable materials cost are identified both for single and multiple ingot slicing.

  19. Double diameter boring tool

    DOEpatents

    Ashbaugh, F.A.; Murry, K.R.

    1986-02-10

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting flutes formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first flute tip to the axis of rotation plus the distance from the second flute tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second flute tip to the axis of rotation minus one-half the distance from the first flute tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  20. Double diameter boring tool

    DOEpatents

    Ashbaugh, Fred N.; Murry, Kenneth R.

    1988-12-27

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  1. Small diameter carbon nanopipettes

    NASA Astrophysics Data System (ADS)

    Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

    2010-01-01

    Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 °C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 °C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

  2. CPAP of 10 cmH2O during cardiopulmonary bypass followed by an alveolar recruitment manoeuvre does not improve post-bypass oxygenation compared to a recruitment manoeuvre alone in children.

    PubMed

    Kim, J T; Na, H S; Kim, H S; Kim, C S; Kim, S D

    2010-03-01

    This randomised controlled study assessed whether continuous positive airway pressure (CPAP) of 10 cmH2O during cardiopulmonary bypass improves post-bypass oxygenation in children compared with no CPAP during bypass. We studied children with a ventricular septal defect. CPAP of 10 cmH2O was applied during bypass in the CPAP group (n=24), whereas the lungs were left deflated in the control group (n=20). In both groups, an alveolar recruitment maneuver was performed by applying positive pressure of 30 to 40 cmH2O for five seconds before weaning from bypass. Postoperative ventilation had the peak inflation pressure set to produce an expired tidal volume of 8 ml/kg with positive end expiratory pressure of 5 cmH2O. Arterial blood gas and haemodynamic measurements were performed at skin incision, five minutes after weaning from bypass, five minutes after chest closure and four hours after arrival in the intensive care unit. In four children CPAP was discontinued because it adversely affected the operating field. There was no difference in demographic characteristics, haemodynamic data, bypass time and operation time. No difference was observed between the groups with respect to pH, PaO2, P(A-a) DO2, PaCO2, and ETCO2 at each time. Variability in the data was greater than expected, leading to a decrease in the expected power of the study. CPAP at 10 cmH2O during bypass was not found to improve the post-bypass oxygenation as compared with leaving the lung deflated during bypass in children undergoing ventricular septal defect repair who had an alveolar recruitment maneuver at the end of bypass. PMID:20369762

  3. The DIAMET campaign

    NASA Astrophysics Data System (ADS)

    Vaughan, G.

    2012-04-01

    DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) is a joint project between the UK academic community and the Met Office. Its focus is on understanding and predicting mesoscale structures in synoptic-scale storms, and in particular on the role of diabatic processes in generating and maintaining them. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. The project conducted two field campaigns in the autumn of 2011, from September 14 - 30 and November 24 - December 14, based around the FAAM BAe146 aircraft with support from ground-based radar and radiosonde measurements. Detailed modelling, mainly using the Met Office Unified model, supported the planning and interpretation of these campaigns. This presentation will give a brief overview of the campaigns. Both in September and November-December the weather regime was westerly, with a strong jet stream directed across the Atlantic. Three IOPs were conducted in September, to observe a convective band ahead of an upper-level trough, waves on a long trailing cold front, and a warm conveyor belt associated with a secondary cyclone. In November-December six IOPs were conducted, to observe frontal passages and high winds. This period was notable for a number of very strong windstorms passing across the north of the UK, and gave us an opportunity to examine bent-back warm fronts in the southern quadrant of these storms where the strongest winds are found. The case studies fell into two basic patterns. In the majority of cases, dropsonde legs at high level were used to obtain a cross-section of winds and thermodynamic structure (e.g. across a front), followed by in situ legs at lower levels (generally where the temperature was between 0 and -10°) to examine microphysical processes, especially ice multiplication and the extent of supercooled water

  4. Wheel Diameter and Speedometer Reading

    ERIC Educational Resources Information Center

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  5. Measuring Diameters Of Large Vessels

    NASA Technical Reports Server (NTRS)

    Currie, James R.; Kissel, Ralph R.; Oliver, Charles E.; Smith, Earnest C.; Redmon, John W., Sr.; Wallace, Charles C.; Swanson, Charles P.

    1990-01-01

    Computerized apparatus produces accurate results quickly. Apparatus measures diameter of tank or other large cylindrical vessel, without prior knowledge of exact location of cylindrical axis. Produces plot of inner circumference, estimate of true center of vessel, data on radius, diameter of best-fit circle, and negative and positive deviations of radius from circle at closely spaced points on circumference. Eliminates need for time-consuming and error-prone manual measurements.

  6. Wheel Diameter and Speedometer Reading

    NASA Astrophysics Data System (ADS)

    Murray, Clifton

    2010-09-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it makes a good illustration of how reasoning in physics can lead to a result that is useful outside the classroom.

  7. Parameterization Measurements of a 963 cm3 LaBr3:Ce Crystal

    NASA Astrophysics Data System (ADS)

    Marsh, J. C.; Litz, M. S.; Chiara, C. J.; Carroll, J. J.

    2015-04-01

    LaBr3:Ce is a relatively new scintillator with characteristics that surpass more commonly used radiation detection scintillators. Published results for small (< 10 cm3) LaBr3 detectors (NIMA 683, 46, 2012) describe improved time resolutions (~ 35 ps), energy resolutions (~3.5% at 662 keV), and optical yields (~63,000 photons/MeV) compared to NaI and BGO. Here it was possible to assess the characteristics of a 963 cm3 (7.6 cm length, 12.7 cm diameter) cylindrical crystal optically coupled to an ET9390KB photomultiplier tube optimized for crystal emissions at 380 nm. A 3 × 3 array of crystals will be used for neutron-stimulated evaluations of materials for elemental and chemical composition. A custom bleeder chain was designed to minimize current saturation and optimize the energy linearity over a 2-12 MeV energy range. Because large volume crystal characteristics do not always scale linearly, energy resolution, detector efficiency, crystal homogeneity, timing resolution, pulse shape, peak-to-Compton ratios, energy linearity, and self activity were all measured and compared to published results on other LaBr3 detectors. Advantages and disadvantages of such large LaBr3 crystals will be discussed, and future plans will be described. This work was supported by the Army Research Laboratory under Cooperative Agreement W911NF-12-2-0019.

  8. Stellar diameters and temperatures. IV. Predicting stellar angular diameters

    SciTech Connect

    Boyajian, Tabetha S.; Van Belle, Gerard; Von Braun, Kaspar

    2014-03-01

    The number of stellar angular diameter measurements has greatly increased over the past few years due to innovations and developments in the field of long baseline optical interferometry. We use a collection of high-precision angular diameter measurements for nearby, main-sequence stars to develop empirical relations that allow the prediction of stellar angular sizes as a function of observed photometric color. These relations are presented for a combination of 48 broadband color indices. We empirically show for the first time a dependence on metallicity of these relations using Johnson (B – V) and Sloan (g – r) colors. Our relations are capable of predicting diameters with a random error of less than 5% and represent the most robust and empirical determinations of stellar angular sizes to date.

  9. TRAC-PF1/MOD1 calculations and data comparisons for MIST (Multi-Loop Integral System Test) small-break loss-of-coolant accidents with scaled 10 cm/sup 2/ and 50 cm/sup 2/ breaks

    SciTech Connect

    Steiner, J.L.; Siebe, D.A.; Boyack, B.E.

    1987-01-01

    Los Alamos National Laboratory is a participant in the Integral System Test (IST) program initiated in June 1983 for the purpose of providing integral system test data on specific issues/phenomena relevant to post-small-break loss-of-coolant accidents (SBLOCAs), loss of feedwater and other transients in Babcock and Wilcox (B and W) plant designs. The Multi-Loop Integral System Test (MIST) facility is the largest single component in the IST program. MIST is a 2 x 4 (2 hot legs and steam generators, 4 cold legs and reactor-coolant pumps) representation of lowered-loop reactor systems of the B and W design. It is a full-height, full-pressure facility with 1/817 power and volume scaling. Two other experimental facilities are included in the IST program: test loops at the University of Maryland, College Park, and at Stanford Research Institute. The objective of the IST tests is to generate high-quality experimental data to be used for assessing thermal-hydraulic safety computer codes. Efforts are underway at Los Alamos to assess TRAC-PF1/MOD1 against data from each of the IST facilities. Calculations and data comparisons for TRAC-PF1/MOD1 assessment have been completed for two transients run in the MIST facility. These are the MIST nominal test. Test 3109AA, a scaled 10 cm/sup 2/ SBLOCA and Test 320201, a scaled 50 cm/sup 2/ SBLOCA. Only MIST assessment results are presented in this paper.

  10. High voltage variable diameter insulator

    DOEpatents

    Vanacek, D.L.; Pike, C.D.

    1982-07-13

    A high voltage feedthrough assembly having a tubular insulator extending between the ground plane ring and the high voltage ring. The insulator is made of Pyrex and decreases in diameter from the ground plane ring to the high voltage ring, producing equipotential lines almost perpendicular to the wall of the insulator to optimize the voltage-holding capability of the feedthrough assembly.

  11. High voltage variable diameter insulator

    DOEpatents

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  12. Pulsed-laser crystallized highly conductive boron-doped microcrystalline silicon

    SciTech Connect

    Nebel, C.E.; Dahlheimer, B.; Karrer, U.; Stutzmann, M.

    1997-07-01

    The preparation of seed lattices, using three interfering beams (TIB) from a pulsed Nd:YAG laser in a-Si layers of 100 to 400 nm thickness is introduced and applied for seeded laser or thermally induced crystallization of a-Si on Corning 7059 glass. The structural and electronic properties of the {micro}c-Si layers are investigated by X-ray, electron- and atomic force microscopy, Hall and conductivity measurements. In highly boron-doped {micro}c-Si, grains up to 1.3 {micro}m in diameter are detected, giving rise to conductivities of {approx}2,000 S/cm and hole mobilities of {approx}10 cm{sup 2}/Vs.

  13. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  14. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  15. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  16. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a...

  17. 7 CFR 51.2934 - Diameter.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Standards for Grades of Apricots Definitions § 51.2934 Diameter. Diameter means the greatest diameter, measured through the center of the apricot, at right angles to a line running from the stem to the...

  18. Diameter Dependence of the Transport Properties of Antimony Telluride Nanowires

    NASA Astrophysics Data System (ADS)

    Zuev, Yuri; Lee, Jin Sook; Park, Hongkun; Kim, Philip

    2010-03-01

    We report measurements of electronic, thermoelectric, and galvanometric properties of individual semimetallic single crystal antimony telluride (Sb2Te3) nanowires. Microfabricated heater and thermometer electrodes were used to probe the transport properties of the nanowires with diameters in the range of 22 - 95nm and temperatures in the range of 2 - 300K. Temperature dependent resistivity varies depending on nanowire diameter. Thermoelectric power (TEP) measurements indicate hole dominant diffusive thermoelectric generation, with an enhancement of the TEP for smaller diameter wires. The large surface-to-volume ratio of Sb2Te3 nanowires makes them an excellent platform to explore novel phenomena in this predicted topological insulator. We investigate mesoscopic magnetoresistance effects in magnetic fields both parallel and perpendicular to the nanowire axis.

  19. A hollow cathode neutralizer for a 30-cm diameter bombardment thruster

    NASA Technical Reports Server (NTRS)

    Bechtel, R. T.

    1973-01-01

    Recent improvements in overall thrustor performance have imposed new constraints on neutralizer performance. The use of compensated grid extraction system requires a re-evaluation of neutralizer position. In addition a suitable control logic for the neutralizer has proven difficult. A series of tests were conducted to determine what effect neutralizer cathode geometry has on performance. The parameters investigated included orifice diameter and length, and cathode diameter. Similar tests investigated open and enclosed keeper geometries. Neutralizer position tests with compensated grids suggest positions approximately 10 cm from the accelerator and radially out of the beam envelope should result in satisfactory performance and long life. Finally operation at keeper currents of 1.5 amp has resulted in lower total neutralizer power, the elimination of tip heater power, and suitable closed loop control of the neutralizer vaporizer.

  20. 7 CFR 51.2656 - Diameter.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry....

  1. MWD tool for deep, small diameter boreholes

    SciTech Connect

    Buytaert, J.P.R.; Duckworth, A.

    1992-03-17

    This patent describes an apparatus for measuring a drilling parameters while drilling a borehole in an earth formation, wherein the borehole includes a small diameter deep borehole portion and a large diameter upper borehole portion. It includes small diameter drillstring means for drilling the deep borehole portion; sensor means, disposed within the small diameter drillstring means, for measuring a drilling parameter characteristic of the deep portion of the borehole while drilling the deep portion of the borehole and for providing sensor output signals indicative of the measured parameter; an upper drillstring portion extending between the surface of the formation and the small diameter drillstring means, the upper drillstring portion including a large diameter drillstring portion; data transmission means disposed within the large diameter drillstring portion and responsive to the sensor output.

  2. Ecological importance of large-diameter trees in a temperate mixed-conifer forest.

    PubMed

    Lutz, James A; Larson, Andrew J; Swanson, Mark E; Freund, James A

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m(2). We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by

  3. Ecological Importance of Large-Diameter Trees in a Temperate Mixed-Conifer Forest

    PubMed Central

    Lutz, James A.; Larson, Andrew J.; Swanson, Mark E.; Freund, James A.

    2012-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. Although both scaling theory and competition theory make predictions about the relative composition and spatial patterns of large-diameter trees compared to smaller diameter trees, these predictions are rarely tested. We established a 25.6 ha permanent plot within which we tagged and mapped all trees ≥1 cm dbh, all snags ≥10 cm dbh, and all shrub patches ≥2 m2. We sampled downed woody debris, litter, and duff with line intercept transects. Aboveground live biomass of the 23 woody species was 507.9 Mg/ha, of which 503.8 Mg/ha was trees (SD = 114.3 Mg/ha) and 4.1 Mg/ha was shrubs. Aboveground live and dead biomass was 652.0 Mg/ha. Large-diameter trees comprised 1.4% of individuals but 49.4% of biomass, with biomass dominated by Abies concolor and Pinus lambertiana (93.0% of tree biomass). The large-diameter component dominated the biomass of snags (59.5%) and contributed significantly to that of woody debris (36.6%). Traditional scaling theory was not a good model for either the relationship between tree radii and tree abundance or tree biomass. Spatial patterning of large-diameter trees of the three most abundant species differed from that of small-diameter conspecifics. For A. concolor and P. lambertiana, as well as all trees pooled, large-diameter and small-diameter trees were spatially segregated through inter-tree distances <10 m. Competition alone was insufficient to explain the spatial patterns of large-diameter trees and spatial relationships between large-diameter and small-diameter trees. Long-term observations may reveal regulation of forest biomass and spatial structure by fire, wind, pathogens, and insects in Sierra Nevada mixed-conifer forests. Sustaining ecosystem functions such as carbon storage or provision of specialist species habitat will likely require different management strategies when the functions are performed primarily by a

  4. The Importance of Large-Diameter Trees to Forest Structural Heterogeneity

    PubMed Central

    Lutz, James A.; Larson, Andrew J.; Freund, James A.; Swanson, Mark E.; Bible, Kenneth J.

    2013-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥1 cm dbh, all 1,966 snags ≥10 cm dbh, and all shrub patches ≥2 m2. Basal area of the 26 woody species was 62.18 m2/ha, of which 61.60 m2/ha was trees and 0.58 m2/ha was tall shrubs. Large-diameter trees (≥100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P≤0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses. PMID:24376579

  5. The importance of large-diameter trees to forest structural heterogeneity.

    PubMed

    Lutz, James A; Larson, Andrew J; Freund, James A; Swanson, Mark E; Bible, Kenneth J

    2013-01-01

    Large-diameter trees dominate the structure, dynamics and function of many temperate and tropical forests. However, their attendant contributions to forest heterogeneity are rarely addressed. We established the Wind River Forest Dynamics Plot, a 25.6 ha permanent plot within which we tagged and mapped all 30,973 woody stems ≥ 1 cm dbh, all 1,966 snags ≥ 10 cm dbh, and all shrub patches ≥ 2 m(2). Basal area of the 26 woody species was 62.18 m(2)/ha, of which 61.60 m(2)/ha was trees and 0.58 m(2)/ha was tall shrubs. Large-diameter trees (≥ 100 cm dbh) comprised 1.5% of stems, 31.8% of basal area, and 17.6% of the heterogeneity of basal area, with basal area dominated by Tsuga heterophylla and Pseudotsuga menziesii. Small-diameter subpopulations of Pseudotsuga menziesii, Tsuga heterophylla and Thuja plicata, as well as all tree species combined, exhibited significant aggregation relative to the null model of complete spatial randomness (CSR) up to 9 m (P ≤ 0.001). Patterns of large-diameter trees were either not different from CSR (Tsuga heterophylla), or exhibited slight aggregation (Pseudotsuga menziesii and Thuja plicata). Significant spatial repulsion between large-diameter and small-diameter Tsuga heterophylla suggests that large-diameter Tsuga heterophylla function as organizers of tree demography over decadal timescales through competitive interactions. Comparison among two forest dynamics plots suggests that forest structural diversity responds to intermediate-scale environmental heterogeneity and disturbances, similar to hypotheses about patterns of species richness, and richness- ecosystem function. Large mapped plots with detailed within-plot environmental spatial covariates will be required to test these hypotheses. PMID:24376579

  6. Influence of hole diameter on the average size and quantity distribution of Si nanoparticles

    NASA Astrophysics Data System (ADS)

    Chu, Lizhi; Zong, Yu; Deng, Zechao; Ding, Xuecheng; Zhao, Hongdong; Wang, Yinglong

    2013-12-01

    The single crystalline Si target with high resistivity was ablated by a XeCl excimer laser (wavelength 308nm) in pure Ar gas under the ambient pressure of 10 Pa. The mask with a 1-10 mm diameter hole in the center was placed at a distance of 1.5 cm to the Si target. The Si nanocrystalline films were systemically deposited on a glass or single crystalline Si substrate placed behind the mask parallelly with a distance of 1.0 cm. The Raman and X-ray diffraction spectra indicate that the films were nanocrystalline. Scanning electron microscope images of the films showed that the diameter of the hole affected on the quantity and distributed range of Si nanoparticles on the substrate. It was obtained that the average size of Si nanoparticles decreasing with the diameter of the hole increasing, the quantity of Si nanoparticles was proportional to the power of 1.5 of the hole diameter. It is the nonlinear dynamic process to lead to the experimental result.

  7. Graft Diameter matters in Hamstring ACL reconstruction

    PubMed Central

    Clatworthy, Mark

    2016-01-01

    Objective: Recently techniques have been developed to increase graft diameter in hamstring ACL reconstruction with the hope to decrease graft failure. To date there is limited evidence to show that a smaller graft diameter results in a higher ACL failure rate. Method: The factors for failure in 1480 consecutive single surgeon hamstring ACL reconstructions were evaluated prospectively. Patients were followed for 2-15 years. A multivariate analysis was performed which looked at graft size, age, sex, time to surgery, meniscal integrity, meniscal repair and ACL graft placement to determine whether graft diameter matters in determining the failure of hamstring ACL reconstruction. Results: Graft diameters ranged from 6-10 mm. The mean graft diameter for all patients was 7.75 mm. 83 ACL reconstructions failed. The mean size of graft failures was 7.55 mm ACL reconstructions that failed had a significantly smaller hamstring graft diameter p=0.001. The Hazard Ratio for a smaller diameter graft is 0.517 p=<0.0001. For every 1 mm decrease in graft diameter there is a 48.3% higher chance of failure. The multivariate analysis showed a hazard ratio of 0.543 p=0.002. For every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure. Conclusion: Smaller diameter hamstring grafts do have a higher failure rate. Grafts ≤ 7.5 mm had twice the failure rate of grafts ≥8 mm using a multivariate analysis for every 1 mm decrease in graft diameter there is a 45.7% higher chance of failure.

  8. Shrinking plastic tubing and nonstandard diameters

    NASA Technical Reports Server (NTRS)

    Ruiz, W. V.; Thatcher, C. S.

    1980-01-01

    Process allows larger-than-normal postshrink diameters without splitting. Tetrafluoroethylene tubing on mandrel is supported within hot steel pipe by several small diameter coil sections. Rising temperature of mandrel is measured via thermocouple so assembly can be removed without overshrinking (and splitting) of tubing.

  9. Ecological Importance of Small-Diameter Trees to the Structure, Diversity and Biomass of a Tropical Evergreen Forest at Rabi, Gabon.

    PubMed

    Memiaghe, Hervé R; Lutz, James A; Korte, Lisa; Alonso, Alfonso; Kenfack, David

    2016-01-01

    Tropical forests have long been recognized for their biodiversity and ecosystem services. Despite their importance, tropical forests, and particularly those of central Africa, remain understudied. Until recently, most forest inventories in Central Africa have focused on trees ≥10 cm in diameter, even though several studies have shown that small-diameter tree population may be important to demographic rates and nutrient cycling. To determine the ecological importance of small-diameter trees in central African forests, we used data from a 25-ha permanent plot that we established in the rainforest of Gabon to study the diversity and dynamics of these forests. Within the plot, we censused 175,830 trees ≥1 cm dbh from 54 families, 192 genera, and 345 species. Average tree density was 7,026 trees/ha, basal area 31.64 m2/ha, and above-ground biomass 369.40 Mg/ha. Fabaceae, Ebenaceae and Euphorbiaceae were the most important families by basal area, density and above-ground biomass. Small-diameter trees (1 cm ≥ dbh <10 cm) comprised 93.7% of the total tree population, 16.5% of basal area, and 4.8% of the above-ground biomass. They also had diversity 18% higher at family level, 34% higher at genus level, and 42% higher at species level than trees ≥10 cm dbh. Although the relative contribution of small-diameter trees to biomass was comparable to other forests globally, their contribution to forest density, and diversity was disproportionately higher. The high levels of diversity within small-diameter classes may give these forests high levels of structural resilience to anthropogenic/natural disturbance and a changing climate. PMID:27186658

  10. Ecological Importance of Small-Diameter Trees to the Structure, Diversity and Biomass of a Tropical Evergreen Forest at Rabi, Gabon

    PubMed Central

    Memiaghe, Hervé R.; Lutz, James A.; Korte, Lisa; Alonso, Alfonso; Kenfack, David

    2016-01-01

    Tropical forests have long been recognized for their biodiversity and ecosystem services. Despite their importance, tropical forests, and particularly those of central Africa, remain understudied. Until recently, most forest inventories in Central Africa have focused on trees ≥10 cm in diameter, even though several studies have shown that small-diameter tree population may be important to demographic rates and nutrient cycling. To determine the ecological importance of small-diameter trees in central African forests, we used data from a 25-ha permanent plot that we established in the rainforest of Gabon to study the diversity and dynamics of these forests. Within the plot, we censused 175,830 trees ≥1 cm dbh from 54 families, 192 genera, and 345 species. Average tree density was 7,026 trees/ha, basal area 31.64 m2/ha, and above-ground biomass 369.40 Mg/ha. Fabaceae, Ebenaceae and Euphorbiaceae were the most important families by basal area, density and above-ground biomass. Small-diameter trees (1 cm ≥ dbh <10 cm) comprised 93.7% of the total tree population, 16.5% of basal area, and 4.8% of the above-ground biomass. They also had diversity 18% higher at family level, 34% higher at genus level, and 42% higher at species level than trees ≥10 cm dbh. Although the relative contribution of small-diameter trees to biomass was comparable to other forests globally, their contribution to forest density, and diversity was disproportionately higher. The high levels of diversity within small-diameter classes may give these forests high levels of structural resilience to anthropogenic/natural disturbance and a changing climate. PMID:27186658

  11. Photoacoustic determination of blood vessel diameter

    NASA Astrophysics Data System (ADS)

    Kolkman, Roy G. M.; Klaessens, John H. G. M.; Hondebrink, Erwin; Hopman, Jeroen C. W.; de Mul, Frits F. M.; Steenbergen, Wiendelt; Thijssen, Johan M.; van Leeuwen, Ton G.

    2004-10-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-to-peak time (tgrpp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel diameter showed that the diameter could be approximated by 2ctgrpp, with c the speed of sound in blood. Using this relation, the lateral diameter could also precisely be determined. In vivo imaging and monitoring of changes in vessel diameters was feasible. Finally, acoustic time traces were recorded while flushing a vessel in the rabbit ear with saline, which proved that the main contribution to the laser-induced pressure transient is caused by blood inside the vessel and that the vessel wall gives only a minor contribution.

  12. A 10 cm × 10 cm CdTe Spectroscopic Imaging Detector based on the HEXITEC ASIC

    NASA Astrophysics Data System (ADS)

    Wilson, M. D.; Dummott, L.; Duarte, D. D.; Green, F. H.; Pani, S.; Schneider, A.; Scuffham, J. W.; Seller, P.; Veale, M. C.

    2015-10-01

    The 250 μ m pitch 80x80 pixel HEXITEC detector systems have shown that spectroscopic imaging with an energy resolution of <1 keV FWHM per pixel can be readily achieved in the range of 5-200 keV with Al-pixel CdTe biased to -500 V. This level of spectroscopic imaging has a variety of applications but the ability to produce large area detectors remains a barrier to the adoption of this technology. The limited size of ASICs and defect free CdTe wafers dictates that building large area monolithic detectors is not presently a viable option. A 3-side buttable detector module has been developed to cover large areas with arrays of smaller detectors. The detector modules are 20.35 × 20.45 mm with CdTe bump bonded to the HEXITEC ASIC with coverage up to the edge of the module on three sides. The fourth side has a space of 3 mm to allow I/O wire bonds to be made between the ASIC and the edge of a PCB that routes the signals to a connector underneath the active area of the module. The detector modules have been assembled in rows of five modules with a dead space of 170 μ m between each module. Five rows of modules have been assembled in a staggered height array where the wire bonds of one row of modules are covered by the active detector area of a neighboring row. A data acquisition system has been developed to digitise, store and output the 24 Gbit/s data that is generated by the array. The maximum bias magnitude that could be applied to the CdTe detectors from the common voltage source was limited by the worst performing detector module. In this array of detectors a bias of -400 V was used and the detector modules had 93 % of pixels with better than 1.2 keV FWHM at 59.5 keV. An example of K-edge enhanced imaging for mammography was demonstrated. Subtracting images from the events directly above and below the K-edge of the Iodine contrast agent was able to extract the Iodine information from the image of a breast phantom and improve the contrast of the images. This is just one example where the energy spectrum per pixel can be used to develop new and improve existing X-ray imaging techniques.

  13. Effects of food diameter on bite size per mouthful and chewing behavior.

    PubMed

    Shiozawa, Kouichi; Ohnuki, Yoshiki; Mototani, Yasumasa; Umeki, Daisuke; Ito, Aiko; Saeki, Yasutake; Hanada, Nobuhiro; Okumura, Satoshi

    2016-01-01

    Obesity is well known to be associated with a wide variety of illnesses, and is an increasing problem not only in developed countries but also in developing countries. It is well known that large bite size contributes to excess energy intake and obesity, whereas an increased number of chews before swallowing the food bolus is associated with suppression of obesity. However, the effect of food diameter on bite size per mouthful and on chewing behavior remains poorly understood. Here, we examined the effects of food diameter on bite size and chewing behavior using a masticatory counter during the mastication of stick-type biscuits having the same length (10 cm) and ingredients, but with four different diameters (3.0, 3.5, 4.0, and 8.0 mm). Bite length and bite weight per mouthful were similar among the 3.0, 3.5, and 4.0 mm groups. However, bite length in the 8.0 mm group was significantly smaller, whereas bite weight was significantly greater than in the 3.0/3.5 mm groups. Further, the number of chews gradually increased, whereas the number of chews per bite weight gradually decreased, with an increase of biscuit diameter. These results indicate that a smaller biscuit diameter is associated with a smaller bite weight per mouthful and a greater number of chews per bite weight. This is the first report to quantity the effect of food diameter on bite weight per mouthful and on chewing behavior; these results should be helpful in the design of effective, safe, and low-cost behavioral modification therapy to combat obesity. PMID:26493202

  14. Measurement of shaft diameters by machine vision.

    PubMed

    Wei, Guang; Tan, Qingchang

    2011-07-01

    A machine vision method for accurately measuring the diameters of cylindrical shafts is presented. Perspective projection and the geometrical features of cylindrical shafts are modeled in order to enable accurate measurement of shaft diameters. Some of the model parameters are determined using a shaft of known diameter. The camera model itself includes radial and tangential distortions terms. Experiments were used to measure the accuracy of the proposed method and the effect of the position of the camera relative to the shaft, as well as other factors. PMID:21743525

  15. Growth of nanostructures with controlled diameter

    DOEpatents

    Pfefferle, Lisa; Haller, Gary; Ciuparu, Dragos

    2009-02-03

    Transition metal-substituted MCM-41 framework structures with a high degree of structural order and a narrow pore diameter distribution were reproducibly synthesized by a hydrothermal method using a surfactant and an anti-foaming agent. The pore size and the mesoporous volume depend linearly on the surfactant chain length. The transition metals, such as cobalt, are incorporated substitutionally and highly dispersed in the silica framework. Single wall carbon nanotubes with a narrow diameter distribution that correlates with the pore diameter of the catalytic framework structure were prepared by a Boudouard reaction. Nanostructures with a specified diameter or cross-sectional area can therefore be predictably prepared by selecting a suitable pore size of the framework structure.

  16. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, E.D.; Hooper, F.M.; Reichenbach, M.L.

    1992-08-11

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut. 1 figure.

  17. Precision wire feeder for small diameter wire

    DOEpatents

    Brandon, Eldon D.; Hooper, Frederick M.; Reichenbach, Marvin L.

    1992-01-01

    A device for feeding small diameter wire having a diameter less than 0.04 mm (16 mil) to a welding station includes a driving wheel for controllably applying a non-deforming driving force to the wire to move the free end of the wire towards the welding station; and a tension device such as a torque motor for constantly applying a reverse force to the wire in opposition to the driving force to keep the wire taut.

  18. Making Jointless Dual-Diameter Tubes

    NASA Technical Reports Server (NTRS)

    Kirkham, Kathleen E.

    1989-01-01

    Welds between sections having different diameters eliminated. Single tube made with integral tapered transition section between straight sections of different diameters and wall thicknesses. Made from single piece; contains no joints, welded or otherwise. Not prone to such weld defects as voids and need not be inspected for them. Tube fabricated by either of two methods: drawing or reduction. Both methods used to fabricate tubes of 316L corrosion-resistant stainless steel for use as heat-exchanger coil.

  19. Ultra-efficient Engine Diameter Study

    NASA Technical Reports Server (NTRS)

    Daggett, David L.; Brown, Stephen T.; Kawai, Ron T.

    2003-01-01

    Engine fan diameter and Bypass Ratio (BPR) optimization studies have been conducted since the beginning of the turbofan age with the recognition that reducing the engine core jet velocity and increasing fan mass flow rate generally increases propulsive efficiency. However, performance tradeoffs limit the amount of fan flow achievable without reducing airplane efficiency. This study identifies the optimum engine fan diameter and BPR, given the advanced Ultra-Efficient Engine Technology (UEET) powerplant efficiencies, for use on an advanced subsonic airframe. Engine diameter studies have historically focused on specific engine size options, and were limited by existing technology and transportation infrastructure (e.g., ability to fit bare engines through aircraft doors and into cargo holds). This study is unique in defining the optimum fan diameter and drivers for future 2015 (UEET) powerplants while not limiting engine fan diameter by external constraints. This report follows on to a study identifying the system integration issues of UEET engines. This Engine Diameter study was managed by Boeing Phantom Works, Seattle, Washington through the NASA Glenn Revolutionary Aero Space Engine Research (RASER) contract under task order 10. Boeing Phantom Works, Huntington Beach, completed the engine/airplane sizing optimization, while the Boeing Commercial Airplane group (BCA) provided design oversight. A separate subcontract to support the overall project was issued to Tuskegee University.

  20. Measures of Solar Diameter with Eclipses: Data Analysis, Problems and Perspectives

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino

    2008-10-01

    The theme of solar diameter variability is presented with the data of solar astrolabes, the four data points of the Solar Disk Sextant and the central eclipses observed near the shadow's limbs. All data are from the last 3 decades. The results obtained with solar astrolabes are different from Northern (Calern) and Southern hemisphere (Rio de Janeiro, Santiago), this is possibly due to atmospheric effect. Eclipses measurements are not affected by atmospheric turbulence because the event's geometry is determined outside the atmosphere, they give systematically larger diameter values than astrolabes. Videos of eclipses are discussed in term of projection on a screen versus direct imaging at the focal plane with filtered telescope. Relations between filters densities, telescope diameters, frame rate of video cameras, and portion of the outer solar limb lost during eclipse imaging are presented. Loss of 0.02'' are typical for 10 cm ND5 filtered telescope. A commercial 60 fps camcorder for Baily beads timing is discussed in terms of signal-to-noise ratio.

  1. Pulsed Doppler: determination of diameter, blood flow velocity, and volumic flow of brachial artery in man.

    PubMed

    Levenson, J A; Peronneau, P A; Simon, A; Safar, M E

    1981-03-01

    A pulsed Doppler velocimeter suitable for the determination of blood flow velocity and volumic flow in peripheral arteries is described. The apparatus has two main characteristics: an adjustable range-gated time system and a double transducer probe. The error in the determination of the angle between the ultrasound beam and flow of blood with this apparatus was less than 2%, and overestimation of the arterial diameter due to the sample volume size did not exceed 0.035 +/- 0.015 cm. The apparatus was used to determine diameter, blood flow velocity and volumic flow of the brachial artery of 22 healthy men. The values were respectively 0.440 +/- 0.010 cm, 9.15 +/- 1.01 cm.s-1 and 85 +/- 10 cm3.min-1. Administration of intravenous nitroglycerin significantly increased the arterial diameter (p less than 0.001) without any significant change in volumic flow. The described pulsed Doppler velocimeter provides an accurate noninvasive method for determining volumic flow in peripheral arteries in clinical investigation and cardiovascular pharmacology. PMID:6455197

  2. Administrative simplification: adoption of a standard for a unique health plan identifier; addition to the National Provider Identifier requirements; and a change to the compliance date for the International Classification of Diseases, 10th Edition (ICD-10-CM and ICD-10-PCS) medical data code sets. Final rule.

    PubMed

    2012-09-01

    This final rule adopts the standard for a national unique health plan identifier (HPID) and establishes requirements for the implementation of the HPID. In addition, it adopts a data element that will serve as an other entity identifier (OEID), or an identifier for entities that are not health plans, health care providers, or individuals, but that need to be identified in standard transactions. This final rule also specifies the circumstances under which an organization covered health care provider must require certain noncovered individual health care providers who are prescribers to obtain and disclose a National Provider Identifier (NPI). Lastly, this final rule changes the compliance date for the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) for diagnosis coding, including the Official ICD-10-CM Guidelines for Coding and Reporting, and the International Classification of Diseases, 10th Revision, Procedure Coding System (ICD-10-PCS) for inpatient hospital procedure coding, including the Official ICD-10-PCS Guidelines for Coding and Reporting, from October 1, 2013 to October 1, 2014. PMID:22950146

  3. DiameterJ: A validated open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-08-01

    Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called "DiameterJ" was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response. PMID:26043061

  4. Large diameter astromast development, phase 1

    NASA Technical Reports Server (NTRS)

    Preiswerk, P. R.; Finley, L. A.; Knapp, K.

    1983-01-01

    Coilable-longeron lattice columns called Astromasts (trademark) were manufactured for a variety of spacecraft missions. These flight structures varied in diameter from 0.2 to 0.5 meter (9 to 19 in.), and the longest Astromast of this type deploys to a length of 30 meters (100 feet). A double-laced diagonal Astromast design referred to as the Supermast (trademark) which, because it has shorter baylengths than an Astromast, is approximately four times as strong. The longeron cross section and composite material selection for these structures are limited by the maximum strain associated with stowage and deployment. As a result, future requirements for deployable columns with high stiffness and strength require the development of both structures in larger diameters. The design, development, and manufacture of a 6.1-m-long (20-ft), 0.75-m-diameter (30-in.), double-laced diagonal version of the Astromast is described.

  5. Videodensitometry for measuring blood vessel diameter.

    PubMed

    Hoornstra, K; Hanselman, J M; Holland, W P; De Wey Peters, G W; Zwamborn, A W

    1980-01-01

    A method employing a special computer for determining the internal diameters of blood vessels from photofluorographic image is described; in vitro and in vivo experiments are performed with the system. The amount of contrast medium injected is restricted to 4 times 3 ml, and it is possible to determine the diameter (in the range from 2 to 16 mm) at any place where blood vessels can be catheterized. In the in vivo experiments the maximum systematic error is +/-5 percent in the 7 to 8 mm range. PMID:7424549

  6. THERMAL EVALUATION OF DIFFERENT DRIFT DIAMETER SIZES

    SciTech Connect

    H.M. Wade

    1999-01-04

    The purpose of this calculation is to estimate the thermal response of a repository-emplaced waste package and its corresponding drift wall surface temperature with different drift diameters. The case examined is that of a 21 pressurized water reactor (PWR) uncanistered fuel (UCF) waste package loaded with design basis spent nuclear fuel assemblies. This calculation evaluates a 3.5 meter to 6.5 meter drift diameter range in increments of 1.0 meters. The time-dependent temperatures of interest, as determined by this calculation, are the spent nuclear fuel cladding temperature, the waste package surface temperature, and the drift wall surface temperature.

  7. Shaft Diameter Measurement Using Structured Light Vision

    PubMed Central

    Liu, Siyuan; Tan, Qingchang; Zhang, Yachao

    2015-01-01

    A method for measuring shaft diameters is presented using structured light vision measurement. After calibrating a model of the structured light measurement, a virtual plane is established perpendicular to the measured shaft axis and the image of the light stripe on the shaft is projected to the virtual plane. On the virtual plane, the center of the measured shaft is determined by fitting the projected image under the geometrical constraints of the light stripe, and the shaft diameter is measured by the determined center and the projected image. Experiments evaluated the measuring accuracy of the method and the effects of some factors on the measurement are analyzed. PMID:26274963

  8. Fabrication of 10nm diameter carbon nanopores

    SciTech Connect

    Radenovic, Aleksandra; Trepagnier, Eliane; Csencsits, Roseann; Downing, Kenneth H; Liphardt, Jan

    2008-09-25

    The addition of carbon to samples, during imaging, presents a barrier to accurate TEM analysis, the controlled deposition of hydrocarbons by a focused electron beam can be a useful technique for local nanometer-scale sculpting of material. Here we use hydrocarbon deposition to form nanopores from larger focused ion beam (FIB) holes in silicon nitride membranes. Using this method, we close 100-200nm diameter holes to diameters of 10nm and below, with deposition rates of 0.6nm per minute. I-V characteristics of electrolytic flow through these nanopores agree quantitatively with a one dimensional model at all examined salt concentrations.

  9. On the Importance of Small Ice Crystals in Tropical Anvil Cirrus

    NASA Technical Reports Server (NTRS)

    Jensen, E. J.; Lawson, P.; Baker, B.; Pilson, B.; Mo, Q.; Heymsfield, A. J.; Bansemer, A.; Bui, T. P.; McGill, M.; Hlavka, D.; Heymsfield, G.; Platnick, S.; Arnold, G. T.; Tanelli, S.

    2009-01-01

    likely caused by shattering of large crystals on the CAS inlet. We argue that past measurements with CAS in cirrus with large crystals present may contain errors due to crystal shattering, and past conclusions derived from these measurements may need to be revisited. Further, we present correlations between CAS spurious concentration and 2D ]S large ]crystal mass from spatially uniform anvil cirrus sampling periods as an approximate guide for estimating quantitative impact of large ]crystal shattering on CAS concentrations in previous datasets. We use radiative transfer calculations to demonstrate that in the maritime anvil cirrus sampled during TC4, small crystals indicated by 2D ]S contribute relatively little cloud extinction, radiative forcing, or radiative heating in the anvils, regardless of anvil age or vertical location in the clouds. While 2D ]S ice concentrations in fresh anvil cirrus may often exceed 1 cm.3, and are observed to exceed 10 cm.3 in turrets, they are typically 0.1 cm.3 and rarely exceed 1 cm.3 (<1.4% of the time) in aged anvil cirrus. We hypothesize that isolated occurrences of higher ice concentrations in aged anvil cirrus may be caused by ice nucleation driven by either small ]scale convection or gravity waves. It appears that the numerous small crystals detrained from convective updrafts do not persist in the anvil cirrus sampled during TC ]4.

  10. Optical receivers with large-diameter photodiode

    NASA Astrophysics Data System (ADS)

    Swoboda, Robert; Schneider, Kerstin; Zimmermann, Horst

    2006-04-01

    This work presents two types of optical receivers with large-diameter photodiodes. Both are optoelectronic integrated circuits (OEICs) realized in 0.6μm BiCMOS Si technology integrating PIN photodiode, transimpedance amplifier (TIA) and output circuit on chip. The two circuits are an optocoupler with a photodiode diameter of 780μm and a rise- and falltime of 5ns and 4.9ns respectively at 850nm light and a plastic optical fiber (POF) receiver with a photodiode diameter of 500μm and upper -3dB cut-off frequencies of 165MHz at 660nm light and 148MHz at 850nm light. The measured rise- and falltime of the POF receiver was 1.78ns and 2.45ns at 660nm light and 1.94ns and 2.5ns at 850ns, respectively. The presented results combine the advantage of easier handling of large-diameter photodiode receivers and high performance.

  11. Changing the Diameter of a Viewing Tube

    ERIC Educational Resources Information Center

    Obara, Samuel

    2009-01-01

    This article is about the students' investigation about the relationship between the diameter of the view tubes (x) of constant lengths and the viewable vertical distance (y) on the wall while keeping the perpendicular distance from the eyeball to the wall constant. The students collected data and used and represented it in tabular and graphical…

  12. Small diameter symmetric networks from linear groups

    NASA Technical Reports Server (NTRS)

    Campbell, Lowell; Carlsson, Gunnar E.; Dinneen, Michael J.; Faber, Vance; Fellows, Michael R.; Langston, Michael A.; Moore, James W.; Multihaupt, Andrew P.; Sexton, Harlan B.

    1992-01-01

    In this note is reported a collection of constructions of symmetric networks that provide the largest known values for the number of nodes that can be placed in a network of a given degree and diameter. Some of the constructions are in the range of current potential engineering significance. The constructions are Cayley graphs of linear groups obtained by experimental computation.

  13. Reducing the diameters of computer networks

    NASA Technical Reports Server (NTRS)

    Bokhari, S. H.; Raza, A. D.

    1986-01-01

    Three methods of reducing the diameters of computer networks by adding additional processor to processor links under the constraint that no more than one I/O port be added to each processor are discussed. This is equivalent to adding edges to a given graph under the constraint that the degree of any node be increased, at most, by one.

  14. Computing Minimum Diameter Color-Spanning Sets

    NASA Astrophysics Data System (ADS)

    Fleischer, Rudolf; Xu, Xiaoming

    We study the minimum diameter color-spanning set problem which has recently drawn some attention in the database community. We show that the problem can be solved in polynomial time for L 1 and L ∞ metrics, while it is NP-hard for all other L p metrics even in two dimensions. However, we can efficiently compute a constant factor approximation.

  15. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to a line from stem to blossom end. When measuring for maximum size, “diameter” means the smallest dimension of the apple determined...

  16. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  17. 7 CFR 51.320 - Diameter.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter” means the greatest dimension of the apple measured at right angles to... dimension of the apple determined by passing the apple through a round opening in any position....

  18. Nanoscale size effects in crystallization of metallic glass nanorods.

    PubMed

    Sohn, Sungwoo; Jung, Yeonwoong; Xie, Yujun; Osuji, Chinedum; Schroers, Jan; Cha, Judy J

    2015-01-01

    Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding. PMID:26323828

  19. Nanoscale size effects in crystallization of metallic glass nanorods

    PubMed Central

    Sohn, Sungwoo; Jung, Yeonwoong; Xie, Yujun; Osuji, Chinedum; Schroers, Jan; Cha, Judy J.

    2015-01-01

    Atomistic understanding of crystallization in solids is incomplete due to the lack of appropriate materials and direct experimental tools. Metallic glasses possess simple metallic bonds and slow crystallization kinetics, making them suitable to study crystallization. Here, we investigate crystallization of metallic glass-forming liquids by in-situ heating metallic glass nanorods inside a transmission electron microscope. We unveil that the crystallization kinetics is affected by the nanorod diameter. With decreasing diameters, crystallization temperature decreases initially, exhibiting a minimum at a certain diameter, and then rapidly increases below that. This unusual crystallization kinetics is a consequence of multiple competing factors: increase in apparent viscosity, reduced nucleation probability and enhanced heterogeneous nucleation. The first two are verified by slowed grain growth and scatter in crystallization temperature with decreasing diameters. Our findings provide insight into relevant length scales in crystallization of supercooled metallic glasses, thus offering accurate processing conditions for predictable metallic glass nanomolding. PMID:26323828

  20. Fabrication of large diameter alumino-silicate K{sup +} sources

    SciTech Connect

    Baca, D.; Chacon-Golcher, E.; Kwan, J.W.; Wu, J.K.

    2003-02-20

    Alumino-silicate K{sup +} sources have been used in HIF experiments for many years. For example the Neutralized Transport Expt. (NTX) and the High Current Transport Expt. (HCX) are now using this type of ion source with diameters of 2.54 cm and 10 cm respectively. These sources have demonstrated ion currents of 80 mA and 700 mA, for typical HIF pulse lengths of 5-10 {micro}s. The corresponding current density is {approx} 10-15 mA/cm{sup 2}, but much higher current density has been observed using smaller size sources. Recently we have improved our fabrication techniques and, therefore, are able to reliably produce large diameter ion sources with high quality emitter surface without defects. This note provides a detailed description of the procedures employed in the fabrication process. The variables in the processing steps affecting surface quality, such as substrate porosity, powder size distribution, coating technique on large area concave surfaces, drying, and heat firing temperature have been investigated.

  1. Feasibility of laparoscopic liver resection for giant hemangioma of greater than 6 cm in diameter

    PubMed Central

    Kim, In Sung

    2014-01-01

    Backgrounds/Aims Liver hemangioma, the most common benign liver tumor, can be safely managed by clinical observation. However, surgical treatment should be considered in a subset of patients with giant hemangioma with abdominal symptoms. We reviewed the feasibility of total laparoscopic liver resection for giant hemangioma of >6 cm in diameter. Methods Nine consecutive patients who underwent total laparoscopic liver resection for giant hemangioma between August 2008 to December 2012 were included in this study. Medical records were retrospectively reviewed for demographic data, laboratory findings, and perioperative results. Results The median age of patients was 36 yrs (range, 31-63). Eight females and 1 male were included in the study. The median size of hemangioma was 11 cm in diameter (range, 6-18) and 5 patients had a hemangioma >10 cm. Indications for surgical treatments were abdominal symptoms in 4 patients, increased size in 5 patients, and uncertain diagnosis in 1 patient. The median operation time was 522 minutes for right hepatectomy, 220 minutes for left lateral sectionectomy, and 90 minutes for wedge resection. The median estimated blood loss was 400 ml (range, 50-900). There was no postoperative morbidity, including Clanvien-Dindo grade I. Conclusions The resection of giant hemangioma demands meticulous surgical technique due to high vascularity and the concomitant risk of intraoperative hemorrhage. Laparoscopic liver resection is feasible with minimal operative complication. Therefore, laparoscopic liver resection can be considered as an option for surgical treatment for giant hemangioma. PMID:26155263

  2. Flux-Dependent Growth Kinetics and Diameter Selectivity in Single-Wall Carbon Nanotube Arrays

    SciTech Connect

    Geohegan, David B; Puretzky, Alexander A; Jackson, Jeremy Joseph; Rouleau, Christopher M; Eres, Gyula; More, Karren Leslie

    2011-01-01

    The nucleation and growth kinetics of single-wall carbon nanotubes in aligned arrays have been measured using fast pulses of acetylene and in situ optical diagnostics in conjunction with low pressure chemical vapor deposition (CVD). Increasing the acetylene partial pressure is shown to decrease nucleation times by three orders of magnitude, permitting aligned nanotube arrays to nucleate and grow to microns lengths within single gas pulses at high (up to 7 micron/s) peak growth rates and short ~ 0.5 s times.Low-frequency Raman scattering (> 10 cm-1) and transmission electron microscopy measurements show that increasing the feedstock flux in both continuous-CVD and pulsed-CVD shifts the product distribution to large single-wall carbon nanotube diameters > 2.5 nm. Sufficiently high acetylene partial pressures in pulsed-CVD appear to temporarily terminate the growth of the fastest- growing, small-diameter nanotubes by overcoating the more catalytically-active, smaller catalyst nanoparticles within the ensemble with non-nanotube carbon in agreement with a growth model. The results indicate that subsets of catalyst nanoparticle ensembles nucleate, grow, and terminate growth within different flux ranges according to their catalytic activity.

  3. Coke from small-diameter tubes analyzed

    SciTech Connect

    Albright, L.F.

    1988-08-29

    The mechanism for coke deposit formation and the nature of the coke itself can vary with the design of the ethylene furnace tube bank. In this article, coke deposits from furnaces with small-diameter pyrolysis tubes are examined. The samples were taken from four furnaces of identical design (Plant B). As in both the first and second installments of the series, the coke deposits were examined using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDAX). The deposits from the small-diameter tubes are compared with the coke deposits from the furnace discussed in earlier articles. Analysis of the coke in both sets of samples are then used to offer recommendations for improved decoking procedures, operating procedures, better feed selection, and better selection of the metallurgy used in furnace tubes, to extend the operating time of the furnace tubes by reducing the amount and type of coke build up.

  4. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, David E.; Petrini, Richard R.; Carter, Gary W.

    1981-01-01

    An improved rod optic system for inspecting small diameter, deep bores. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90.degree. to minimize optical distortion in examining the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable of examining 1/16 inch diameter and up to 4 inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and right angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  5. Small diameter, deep bore optical inspection system

    DOEpatents

    Lord, D.E.; Petrini, R.R.; Carter, G.W.

    An improved rod optic system for inspecting small diameter, deep bores is described. The system consists of a rod optic system utilizing a curved mirror at the end of the rod lens such that the optical path through the system is bent 90/sup 0/ to minimize optical distortion in examing the sides of a curved bore. The system is particularly useful in the examination of small bores for corrosion, and is capable if examing 1/16 inch diameter and up to 4-inch deep drill holes, for example. The positioning of the curved mirror allows simultaneous viewing from shallow and righ angle points of observation of the same artifact (such as corrosion) in the bore hole. The improved rod optic system may be used for direct eye sighting, or in combination with a still camera or a low-light television monitor; particularly low-light color television.

  6. European Projects of Solar Diameter Monitoring

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Bianda, Michele; Arnaud, Jean

    2008-10-01

    Three projects dealing with solar diameter evolution are presently in development. Historical and contemporary eclipses and planetary transits data collection and analysis, to cover potentially the last 5 centuries with an accuracy of few hundreds of arcsecond on diameter's measurements. The French space mission PICARD with a few milliarcseconds accuray. With PICARD-SOL instruments located at the plateau of Calern the role of the atmosphere in ground-based measurements will be clarified. CLAVIUS is a Swiss-Italian project based on drift-scan method, free from optical distortions, where hourly circles transits will be monitored with fast CMOS sensors in different wavebands. The will run at IRSOL Gregory-Coudé telescope.

  7. On finding minimum-diameter clique trees

    SciTech Connect

    Blair, J.R.S. . Dept. of Computer Science); Peyton, B.W. )

    1991-08-01

    It is well-known that any chordal graph can be represented as a clique tree (acyclic hypergraph, join tree). Since some chordal graphs have many distinct clique tree representations, it is interesting to consider which one is most desirable under various circumstances. A clique tree of minimum diameter (or height) is sometimes a natural candidate when choosing clique trees to be processed in a parallel computing environment. This paper introduces a linear time algorithm for computing a minimum-diameter clique tree. The new algorithm is an analogue of the natural greedy algorithm for rooting an ordinary tree in order to minimize its height. It has potential application in the development of parallel algorithms for both knowledge-based systems and the solution of sparse linear systems of equations. 31 refs., 7 figs.

  8. Lasing in microdisks of ultrasmall diameter

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Bogdanov, A. A.; Shostak, I. I.; Moiseev, E. I.; Karpov, D. V.; Laukkanen, J.; Tommila, J.

    2014-12-15

    It is demonstrated by calculations and experimental results that room-temperature lasing can be obtained at the ground-state optical transition of InAs/InGaAs/GaAs quantum dots in optical microcavities with a record-small diameter of 1.5 μm. In 1-μm cavities, lasing occurs at the wavelength of one of the whispering-gallery modes within the band corresponding to the first excited-state optical transition.

  9. Diameter-dependent hydrophobicity in carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kyakuno, Haruka; Fukasawa, Mamoru; Ichimura, Ryota; Matsuda, Kazuyuki; Nakai, Yusuke; Miyata, Yasumitsu; Saito, Takeshi; Maniwa, Yutaka

    2016-08-01

    Single-wall carbon nanotubes (SWCNTs) are a good model system that provides atomically smooth nanocavities. It has been reported that water-SWCNTs exhibit hydrophobicity depending on the temperature T and the SWCNT diameter D. SWCNTs adsorb water molecules spontaneously in their cylindrical pores around room temperature, whereas they exhibit a hydrophilic-hydrophobic transition or wet-dry transition (WDT) at a critical temperature Twd ≈ 220-230 K and above a critical diameter Dc ≈ 1.4-1.6 nm. However, details of the WDT phenomenon and its mechanism remain unknown. Here, we report a systematic experimental study involving X-ray diffraction, optical microscopy, and differential scanning calorimetry. It is found that water molecules inside thick SWCNTs (D > Dc) evaporate and condense into ice Ih outside the SWCNTs at Twd upon cooling, and the ice Ih evaporates and condenses inside the SWCNTs upon heating. On the other hand, residual water trapped inside the SWCNTs below Twd freezes. Molecular dynamics simulations indicate that upon lowering T, the hydrophobicity of thick SWCNTs increases without any structural transition, while the water inside thin SWCNTs (D < Dc) exhibits a structural transition, forming an ordered ice. This ice has a well-developed hydrogen bonding network adapting to the cylindrical pores of the SWCNTs. Thus, the unusual diameter dependence of the WDT is attributed to the adaptability of the structure of water to the pore dimension and shape.

  10. Calibration of area based diameter distribution with individual tree based diameter estimates using airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Xu, Qing; Hou, Zhengyang; Maltamo, Matti; Tokola, Timo

    2014-07-01

    Diameter distribution is essential for calculating stem volume and timber assortments of forest stands. A new method was proposed in this study to improve the estimation of stem volume and timber assortments, by means of combining the Area-based approach (ABA) and individual tree detection (ITD), the two main approaches to deriving forest attributes from airborne laser scanning (ALS) data. Two methods, replacement, and histogram matching were employed to calibrate ABA-derived diameter distributions with ITD-derived diameter estimates at plot level. The results showed that more accurate estimates were obtained when calibrations were applied. In view of the highest accuracy between ABA and ITD, calibrated diameter distributions decreased its relative RMSE of the estimated entire growing stock, saw log and pulpwood fractions by 2.81%, 3.05% and 7.73% points at best, respectively. Calibration improved pulpwood fraction significantly, which contributed to the negligible bias of the estimated entire growing stock.

  11. Variable diameter wind turbine rotor blades

    DOEpatents

    Jamieson, Peter McKeich; Hornzee-Jones, Chris; Moroz, Emilian M.; Blakemore, Ralph W.

    2005-12-06

    A system and method for changing wind turbine rotor diameters to meet changing wind speeds and control system loads is disclosed. The rotor blades on the wind turbine are able to adjust length by extensions nested within or containing the base blade. The blades can have more than one extension in a variety of configurations. A cable winching system, a hydraulic system, a pneumatic system, inflatable or elastic extensions, and a spring-loaded jack knife deployment are some of the methods of adjustment. The extension is also protected from lightning by a grounding system.

  12. Stellar Angular Diameter Relations for Microlensing Surveys

    NASA Astrophysics Data System (ADS)

    Adams, Arthur; Boyajian, Tabetha S.; von Braun, Kaspar

    2016-01-01

    Determining the physical properties of microlensing events depends on having accurate angular radii of the source star. Using long-baseline optical interferometry we are able to determine the angular sizes of nearby stars with uncertainties less than 2 percent. We present empirical estimates of angular diameters for both dwarfs/subgiants and giant stars as functions of five color indices which are relevant to planned microlensing surveys. We find in all considered colors that metallicity does not play a statistically significant role in predicting stellar size for the samples of stars considered.

  13. A 30-cm diameter argon ion source

    NASA Technical Reports Server (NTRS)

    Sovey, J. S.

    1976-01-01

    A 30 cm diameter argon ion source was evaluated. Ion source beam currents up to 4a were extracted with ion energies ranging from 0.2 to 1.5 KeV. An ion optics scaling relation was developed for predicting ion beam extraction capability as a function of total extraction voltage, gas type, and screen grid open area. Ignition and emission characteristics of several hollow cathode geometries were assessed for purposes of defining discharge chamber and neutralizer cathodes. Also presented are ion beam profile characteristics which exhibit broad beam capability well suited for ion beam sputtering applications.

  14. A Variable Diameter Short Haul Civil Tiltrotor

    NASA Technical Reports Server (NTRS)

    Wang, James M.; Jones, Christopher T.; Nixon, Mark W.

    1999-01-01

    The Short-Haul-Civil-tiltrotor (SHCT) component of the NASA Aviation System Capacity Program is an effort to develop the technologies needed for a potential 40-passenger civil tiltrotor. The variable diameter tiltrotor (VDTR) is a Sikorsky concept aimed at improving tiltrotor hover and cruise performance currently limited by disk loading that is much higher in hover than conventional helicopter, and much lower in cruise than turbo-prop systems. This paper describes the technical merits of using a VDTR on a SHCT aircraft. The focus will be the rotor design.

  15. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, Albert L.

    1985-01-01

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade.

  16. Thread gauge for measuring thread pitch diameters

    DOEpatents

    Brewster, A.L.

    1985-11-19

    A thread gauge which attaches to a vernier caliper to measure the thread pitch diameter of both externally threaded and internally threaded parts is disclosed. A pair of anvils are externally threaded with threads having the same pitch as those of the threaded part. Each anvil is mounted on a stem having a ball on which the anvil can rotate to properly mate with the parts to which the anvils are applied. The stems are detachably secured to the caliper blades by attachment collars having keyhole openings for receiving the stems and caliper blades. A set screw is used to secure each collar on its caliper blade. 2 figs.

  17. The diameter and albedo of 1943 Anteros

    NASA Technical Reports Server (NTRS)

    Veeder, G. J.; Tedesco, E. F.; Tholen, D. J.; Tokunaga, A.; Matthews, K.; Neugebauer, G.; Soifer, B. T.; Kowal, C.

    1981-01-01

    The results of broadband visual and infrared photometry of the Apollo-Amor asteroid 1943 Anteros during its 1980 apparition are reported. By means of a radiometric model, a diameter of 2.3 + or - 0.2 km and a visual geometric albedo of 0.13 + or - 0.03 is calculated. The albedo and reflectance spectrum of Anteros imply that it is a type S asteroid. Thus, Anteros may have a silicate surface similar to other Apollo-Amor asteroids as well as some stony-iron meteorites.

  18. Measurement of Diameter Changes during Irradiation Testing

    SciTech Connect

    Davis, K. L.; Knudson, D. L.; Crepeau, J. C.; Solstad, S.

    2015-03-01

    New materials are being considered for fuel, cladding, and structures in advanced and existing nuclear reactors. Such materials can experience significant dimensional and physical changes during irradiation. Currently in the US, such changes are measured by repeatedly irradiating a specimen for a specified period of time and then removing it from the reactor for evaluation. The time and labor to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data and handling may disturb the phenomena of interest. In-pile detection of changes in geometry is sorely needed to understand real-time behavior during irradiation testing of fuels and materials in high flux US Material and Test Reactors (MTRs). This paper presents development results of an advanced Linear Variable Differential Transformer-based test rig capable of detecting real-time changes in diameter of fuel rods or material samples during irradiation in US MTRs. This test rig is being developed at the Idaho National Laboratory and will provide experimenters with a unique capability to measure diameter changes associated with fuel and cladding swelling, pellet-clad interaction, and crud buildup.

  19. Thirty-centimeter-diameter ion milling source

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.

    1978-01-01

    A 30-cm beam diameter ion source has been designed and fabricated for micromachining and sputtering applications. An argon ion current density of 1 mA/cu cm at 500 eV ion energy was selected as a design operating condition. The completed ion source met the design criteria at this operating condition with a uniform and well-collimated beam having an average variation in current density of + or - 5% over the center of 20 cm of the beam. This ion source has a multipole magnetic field that employs permanent magnets between permeable pole pieces. Langmuir probe surveys of the source plasma support the design concepts of a multipole field and a circumferential cathode to enhance plasma uniformity.

  20. Five meter diameter conical furlable antenna

    NASA Technical Reports Server (NTRS)

    Fortenberry, J. W.; Freeland, R. E.; Moore, D. M.

    1976-01-01

    An investigation was made to demonstrate that a 5-meter-diameter, furlable, conical reflector antenna utilizing a line source feed can be fabricated utilizing composite materials and to prove that the antenna can function mechanically and electrically as prototype flight hardware. The design, analysis, and testing of the antenna are described. An RF efficiency of 55% at 8.5 GHz and a surface error of 0.64 mm rms were chosen as basic design requirements. Actual test measurements yielded an efficiency of 53% (49.77 dB gain) and a surface error of 0.61 mm rms. Atmospherically induced corrosion of the reflector mesh resulted in the RF performance degradation. An assessment of the antenna as compared to the current state of the art technology was made. This assessment included cost, surface accuracy and RF performance, structural and mechanical characteristics, and possible applications.

  1. Development of fine diameter mullite fiber

    NASA Technical Reports Server (NTRS)

    Long, W. G.

    1974-01-01

    Results are presented of a program to develop and evaluate mullite fiber with a mean diameter under two microns. The two micron fiber is produced by a blowing process at room temperature from a low viscosity (10-25 poise) solution. The blown fiber was evaluated for dimensional stability in thermal cycling to 1371 C, and was equivalent to the 5 micron spun B and W mullite fiber. An additive study was conducted to evaluate substitutes for the boron. Three levels of chromium, lithium fluoride, and magnesium were added to the standard composition in place of boron and the fiber produced was evaluated for chemical and dimensional stability in thermal cycling to 1371 C. The magnesium was the most chemically stable, but the chrome additive imparted the best dimensional stability.

  2. Fire protection covering for small diameter missiles

    NASA Technical Reports Server (NTRS)

    Riccitiello, S. R.; Sawko, P. M. (Inventor)

    1979-01-01

    Flexible intumescent protection sheeting of unusually uniform thickness were prepared from epoxy-polysulfide compositions, containing microfibers and the ammonium salt of 1,4-nitroaniline-2-sulfonic acid, as disclosed in U.S. Pat. No. 3,663,464, except that an ammonium salt particle size in the order of 5 to 8 microns and a fiber size of about 1/128th inch in length and 3 to 5 microns in diameter were found critical to obtain the required density of 1.46 to 1.50 g/cc. The insulation sheeting was prepared by a continuous process involving vacuum mixing, calendering, and curing under very strict conditions which depend to some extent upon the thickness of the sheet produced.

  3. Granulation, Irradiance and Diameter Solar Variations

    NASA Astrophysics Data System (ADS)

    Humberto Andrei, Alexandre; Calderari Boscardin, Sergio; Lousada Penna, Jucira; Reis Neto, Eugenio

    2015-08-01

    Though granulation forms the very face of sun’s photosphere, there are no long term registers of it. Observational and computational hardships to define and follow such highly variable “face” have so far prevented the realization of those registers. However, in recent years a large, coherent body of white light images became available. We retrieved white light, full solar disk images from the BBSO, to a total of 1104 treated ones and 1245 treated and compensated for limb darkening ones. The time coverage extends from the year 2000 to 2005, thus covering the rise and fall of the solar cycle 23. For the analysis, only the central 0.35R portion of the Sun was considered. The central portion was then divided into 100 subsectors, to average and discard the deviant results. The analysis goal is to derive the long term behavior of the photosphere granulation, in broad statistical sense. Three statistics were this way calculated: the standard deviation of the counts (that answers to the grains size); the counts difference between the maximum and minimum tenths (that answers to the grains brightness); the degree of the best fit polynomial along lines and columns (that answers to the grains numbers). According to the statistics, there is no significant variation in the number of grains. The grains sizes are the largest by the solar maximum, in excellent agreement with the maximum of the measured diameter. The grains brightness, on the contrary, is minimum at the solar maximum, and again an excellent agreement is verified with the maximum of the measured diameter.

  4. Advances in large-diameter liquid encapsulated Czochralski GaAs

    NASA Technical Reports Server (NTRS)

    Chen, R. T.; Holmes, D. E.; Kirkpatrick, C. G.

    1982-01-01

    The purity, crystalline perfection, and electrical properties of n- and p-type GaAs crystals grown by the liquid encapsulated Czochralski (LEC) technique are evaluated. The determination of the dislocation density, incidence of twinning, microstructure, background purity, mobility, and minority carrier diffusion length is included. The properties of the LEC GaAs crystals are generally comparable to, if not superior to those of small-diameter GaAs material grown by conventional bulk growth techniques. As a result, LEC GaAs is suitable for application to minority carrier devices requiring high-quality and large-area substrates.

  5. Tissue engineered small-diameter vascular grafts.

    PubMed

    Schmedlen, Rachael H; Elbjeirami, Wafa M; Gobin, Andrea S; West, Jennifer L

    2003-10-01

    Arterial occlusive disease remains the leading cause of death in western countries and often requires vascular reconstructive surgery. The limited supply of suitable small-diameter vascular grafts has led to the development of tissue engineered blood vessel substitutes. Many different approaches have been examined, including natural scaffolds containing one or more ECM proteins and degradable polymeric scaffolds. For optimal graft development, many efforts have modified the culture environment to enhance ECM synthesis and organization using bioreactors under physiologic conditions and biochemical supplements. In the past couple of decades, a great deal of progress on TEVGs has been made. Many challenges remain and are being addressed, particularly with regard to the prevention of thrombosis and the improvement of graft mechanical properties. To develop a patent TEVG that grossly resembles native tissue, required culture times in most studies exceed 8 weeks. Even with further advances in the field, TEVGs will likely not be used in emergency situations because of the time necessary to allow for cell expansion, ECM production and organization, and attainment of desired mechanical strength. Furthermore, TEVGs will probably require the use of autologous tissue to prevent an immunogenic response, unless advances in immune acceptance render allogenic and xenogenic tissue use feasible. TEVGs have not yet been subjected to clinical trials, which will determine the efficacy of such grafts in the long term. Finally, off-the-shelf availability and cost will become the biggest hurdles in the development of a feasible TEVG product. Although many obstacles exist in the effort to develop a small-diameter TEVG, the potential benefits of such an achievement are exciting. In the near future, a nonthrombogenic TEVG with sufficient mechanical strength may be developed for clinical trials. Such a graft will have the minimum characteristics of biological tissue necessary to remain patent

  6. Crystal Creations.

    ERIC Educational Resources Information Center

    Whipple, Nona; Whitmore, Sherry

    1989-01-01

    Presents a many-faceted learning approach to the study of crystals. Provides instructions for performing activities including crystal growth and patterns, creating miniature simulations of crystal-containing rock formations, charcoal and sponge gardens, and snowflakes. (RT)

  7. Optical fiber waveguide sagnac interferometer. Phase 1: Multiturn one meter diameter, single mode. [optical gyroscopes

    NASA Technical Reports Server (NTRS)

    Vali, V.

    1977-01-01

    A rotating ring interferometer was constructed using a 100 meters of single mode optical fiber wound on a crystal cylinder. A 20 inch diameter fiber interferometer gyroscope was built and its sensitivity was evaluated. Major noise sources were identified and improvements for the next phase of development were determined. The accuracy of .01 of a fringe can be improved to .0001 by the removal of the noise source.

  8. LED-based digital diameter measurement

    NASA Astrophysics Data System (ADS)

    Kleuver, Wolfram; Becker, Lothar

    1995-01-01

    This paper presents a new industrial sensor for measuring diameters of extreme thin objects. The system is divided in two parts. The first is the emitter and the second the receiver. It is possible to use this system for the automatic inspection of files and wires in the textile industries and wire works. Another application for the sensor is the control of production of chemical files in an extruder. Furthermore we can measure more than one object in the lightbeam because we get information not only about the dimensions also about the position of the objects in the beam. The innovation in this system is the using of a light emitting diode (LED) as emitter and the realization of a long distance of about two or more meters between the two sensorheads. The results of this development are a special kind of optical layout in the emitter to reduce the loss of intensity and minimize the divergence of the lightbeam. It is not necessary to develop an intensity distribution, which is equal over the complete width of the sensorhead. We can show that we have a better dynamic in the system with this feature. The experiments prove that we get the same resolution as a laserbeamsensor. Furthermore one advantage is the eye-safety.

  9. The 15 cm diameter ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1974-01-01

    The startup reliability of a 15 cm diameter mercury bombardment ion thruster which employs a pulsed high voltage tickler electrode on the main and neutralizer cathodes is examined. Startup of the thruster is achieved 100% of the time on the main cathode and 98.7% of the time on the neutralizer cathode over a 3640 cycle test. The thruster was started from a 20 C initial condition and operated for an hour at a 600 mA beam current. An energy efficiency of 75% and a propellant utilization efficiency of 77% was achieved over the complete cycle. The effect of a single cusp magnetic field thruster length on its performance is discussed. Guidelines are formulated for the shaping of magnetic field lines in thrusters. A model describing double ion production in mercury discharges is presented. The production route is shown to occur through the single ionic ground state. Photographs of the interior of an operating-hollow cathode are presented. A cathode spot is shown to be present if the cathode is free of low work-function surfaces. The spot is observed if a low work-function oxide coating is applied to the cathode insert. Results show that low work-function oxide coatings tend to migrate during thruster operation.

  10. Large Circular Basin - 1300-km diameter

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Close-up view of one-half of a 1300-km diameter circular basin the largest observed on Mercury. The other half is hidden beyond the terminator to the left. Hills and valleys extend in a radial fashion outward from the main ring. Interior of the large basin is completely flooded by plains materials; adjacent lowlands are also partially flooded and superimposed on the plains are bowl shaped craters. Wrinkle ridges are abundant on the plains materials. The area shown is 1008 miles (1600 km) from the top to the bottom of the picture. Sun's illumination is from the right. Blurred linear lines extending across the picture near bottom are missing data lines that have been filled in by the computer. Mariner 10 encountered Mercury on Friday, March 29th, 1974, passing the planet on the darkside 431 miles (690-km) from the surface.

    The Mariner 10 mission, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, explored Venus in February 1974 on the way to three encounters with Mercury-in March and September 1974 and in March 1975. The spacecraft took more than 7,000 photos of Mercury, Venus, the Earth and the Moon.

    NOTE: This image was scanned from physical media.

  11. Profile Control by Biased Electrodes in Large Diameter RF Produced Pl asma

    NASA Astrophysics Data System (ADS)

    Shinohara, Shunjiro; Matsuoka, Norikazu; Yoshinaka, Toshiro

    1998-10-01

    Control of the plasma profile has been carried out, using the voltage biasing method in the large diameter (45 cm) RF (radio frequency) produced plasma in the presence of the uniform magnetic field (less than 1200 G). Under the low filling pressure condition of 0.16 mTorr, changing the biasing voltages to the three individual end plates with concentric circular ring shapes, the radial electron density (about 10^10 cm-3) profile could be changed from the hollow to the peaked one. On the contrary, the nearly flat electron temperature (several eV) profile did not change appreciably. The azimuthal rotation velocity measured by the Mach probe, i.e. directional probe, showed the different radial profiles (but nearly uniform along the axis) depending on the biasing voltage. This velocity became slower with the low magnetic field (less than 200 G) or in the higher pressure regime up to 20 mTorr with the higher electron density. The experimental results by other biasing methods will also be presented.

  12. Study on the role of active radicals on plasma sterilization inside small diameter flexible polymeric tubes

    NASA Astrophysics Data System (ADS)

    Mstsuura, Hiroto; Fujiyama, Takatomo; Okuno, Yasuki; Furuta, Masakazu; Okuda, Shuichi; Takemura, Yuichiro

    2015-09-01

    Recently, atmospheric pressure discharge plasma has gathered attention in various fields. Among them, plasma sterilization with many types of plasma source has studied for decades and its mechanism is still an open question. If active radicals produced in plasma has main contribution of killing bacterias, direct contact of the so-called plasma flame might not be necessary. To confirm this, sterilization inside small diameter flexible polymeric tubes is studied in present work. DBD type plasma jet is produce by flowing helium gas in a glass tube. A long polymeric tube is connected and plasma jet is introduced into it. Plasma flame length depends on helium gas flow rate, but limited to about 10 cm in our experimental condition. E.colis set at the exit plasma source is easily killed during 10 min irradiation. At the tube end (about 20 cm away from plasma source exit), sterilization is possible with 30 min operation. This result shows that active radical is produced with helium plasma and mist contained in sample, and it can be transferred more than 20 cm during it life time. More plasma diagnostic data will also be shown at the conference. This work was partially supported by the ''ZE Research Program, IAE(ZE27B-4).

  13. Lasing from fluorescent protein crystals.

    PubMed

    Oh, Heon Jeong; Gather, Malte C; Song, Ji-Joon; Yun, Seok Hyun

    2014-12-15

    We investigated fluorescent protein crystals for potential photonic applications, for the first time to our knowledge. Rod-shaped crystals of enhanced green fluorescent protein (EGFP) were synthesized, with diameters of 0.5-2 μm and lengths of 100-200 μm. The crystals exhibit minimal light scattering due to their ordered structure and generate substantially higher fluorescence intensity than EGFP or dye molecules in solutions. The magnitude of concentration quenching in EGFP crystals was measured to be about 7-10 dB. Upon optical pumping at 485 nm, individual EGFP crystals located between dichroic mirrors generated laser emission with a single-mode spectral line at 513 nm. Our results demonstrate the potential of protein crystals as novel optical elements for self-assembled, micro- or nano-lasers and amplifiers in aqueous environment. PMID:25607090

  14. Crystal growth of large size Dy3Al5O12 garnet single crystals

    NASA Astrophysics Data System (ADS)

    Kimura, Hideo; Sakamoto, Masaru; Numazawa, Takenori; Sato, Mitsunori; Maeda, Hiroshi

    1990-01-01

    Crystal growth conditions using the Czochralski technique were examined in order to be able to grow large-size disprosium-aluminum-garnet single crystals; these are useful as a working material in a practical magnetic refrigeration system. Using the best conditions, large-size bubble-free Dy3Al5O12 single crystals 50 mm in diameter were grown from a stoichiometric melt composition using a seed of Y3Al5O12 single crystal.

  15. Instability of Reference Diameter in the Evaluation of Stenosis After Coronary Angioplasty: Percent Diameter Stenosis Overestimates Dilative Effects Due to Reference Diameter Reduction

    SciTech Connect

    Hirami, Ryouichi; Iwasaki, Kohichiro; Kusachi, Shozo; Murakami, Takashi; Hina, Kazuyoshi; Matano, Shigeru; Murakami, Masaaki; Kita, Toshimasa; Sakakibara, Noburu; Tsuji, Takao

    2000-03-15

    Purpose: To examine changes in the reference segment luminal diameter after coronary angioplasty.Methods: Sixty-one patients with stable angina pectoris or old myocardial infarction were examined. Coronary angiograms were recorded before coronary angioplasty (pre-angioplasty) and immediately after (post-angioplasty), as well as 3 months after. Artery diameters were measured on cine-film using quantitative coronary angiographic analysis.Results: The diameters of the proximal segment not involved in the balloon inflation and segments in the other artery did not change significantly after angioplasty, but the reference segment diameter significantly decreased (4.7%). More than 10% luminal reduction was observed in seven patients (11%) and more than 5% reduction was observed in 25 patients (41%). More than 5% underestimation of the stenosis was observed in 22 patients (36%) when the post-angioplasty reference diameter was used as the reference diameter, compared with when the pre-angioplasty measurement was used and more than 10% underestimation was observed in five patients (8%).Conclusion: This study indicated that evaluation by percent diameter stenosis, with the reference diameter from immediately after angioplasty, overestimates the dilative effects of coronary angioplasty, and that it is thus better to evaluate the efficacy of angioplasty using the absolute diameter in addition to percent luminal stenosis.

  16. Limitations on the Optical Tunability of Small Diameter Gold Nanoshells

    PubMed Central

    Rasch, Michael R.; Sokolov, Konstantin V.; Korgel, Brian A.

    2009-01-01

    Gold (Au) nanoshells were grown on silica nanoparticles with differing average diameters, ranging from 30 nm to 120 nm. Au nanoshells were also formed on silica spheres encapsulating 5 nm diameter magnetic iron oxide nanocrystals. The optical absorbance spectra of these Au nanoshells are reported. The plasmon resonance wavelengths of the smaller diameter nanoshells were significantly less tunable than those of the larger diameter nanoshells. This is due to a reduced range of accessible core-shell ratio—the geometric factor that determines the plasmon peak position—as the silica core diameter shrinks. The smaller diameter nanoshells were also found to be highly prone to aggregation, which broadens the plasmon absorption peak. Model calculations of dispersion stability as a function of silica core diameter reveal that smaller diameter Au shells exhibit more aggregation because of the size-dependence of the electrostatic double-layer potential. PMID:19711913

  17. Nineteen-Foot Diameter Explosively Driven Blast Simulator

    SciTech Connect

    VIGIL,MANUEL G.

    2001-07-01

    This report describes the 19-foot diameter blast tunnel at Sandia National Laboratories. The blast tunnel configuration consists of a 6 foot diameter by 200 foot long shock tube, a 6 foot diameter to 19 foot diameter conical expansion section that is 40 feet long, and a 19 foot diameter test section that is 65 feet long. Therefore, the total blast tunnel length is 305 feet. The development of this 19-foot diameter blast tunnel is presented. The small scale research test results using 4 inch by 8 inch diameter and 2 foot by 6 foot diameter shock tube facilities are included. Analytically predicted parameters are compared to experimentally measured blast tunnel parameters in this report. The blast tunnel parameters include distance, time, static, overpressure, stagnation pressure, dynamic pressure, reflected pressure, shock Mach number, flow Mach number, shock velocity, flow velocity, impulse, flow duration, etc. Shadowgraphs of the shock wave are included for the three different size blast tunnels.

  18. Extrusion of small-diameter, thin-wall tungsten tubing

    NASA Technical Reports Server (NTRS)

    Blankenship, C. P.; Gyorgak, C. A.

    1967-01-01

    Small-diameter, thin-wall seamless tubing of tungsten has been fabricated in lengths of up to 10 feet by hot extrusion over a floating mandrel. Extrusion of 0.50-inch-diameter tubing over 0.4-inch-diameter mandrels was accomplished at temperatures ranging from 3000 degrees to 4000 degrees F.

  19. Biofilm formation on a TiO₂ nanotube with controlled pore diameter and surface wettability.

    PubMed

    Anitha, V C; Lee, Jin-Hyung; Lee, Jintae; Banerjee, Arghya Narayan; Joo, Sang Woo; Min, Bong Ki

    2015-02-13

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ∼17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells. PMID:25604920

  20. Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability

    NASA Astrophysics Data System (ADS)

    Anitha, V. C.; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Joo, Sang Woo; Min, Bong Ki

    2015-02-01

    Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ˜17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.

  1. CT dose equilibration and energy absorption in polyethylene cylinders with diameters from 6 to 55 cm

    SciTech Connect

    Li, Xinhua; Zhang, Da; Liu, Bob

    2015-06-15

    Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose D{sub L}(0) and its rise-to-the-equilibrium curve H(L) = D{sub L}(0)/D{sub eq} from computed tomography (CT) scanning, where D{sub eq} is the equilibrium dose. To aid the use of the phantom in radiation dose assessment and to gain an understanding of dose equilibration and energy absorption in polyethylene, the authors evaluated the short (20 cm) to long (60 cm) phantom dose ratio with a polyethylene diameter of 30 cm, assessed H(L) in polyethylene cylinders of 6–55 cm in diameters, and examined energy absorption in these cylinders. Methods: A GEANT4-based Monte Carlo program was used to simulate the single axial scans of polyethylene cylinders (diameters 6–55 cm and length 90 cm, as well as diameter 30 cm and lengths 20 and 60 cm) on a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare). Axial dose distributions were computed on the phantom central and peripheral axes. An average dose over the central 23 or 100 mm region was evaluated for modeling dose measurement using a 0.6 cm{sup 3} thimble chamber or a 10 cm long pencil ion chamber, respectively. The short (20 cm) to long (90 cm) phantom dose ratios were calculated for the 30 cm diameter polyethylene phantoms scanned at four tube voltages (80–140 kV) and a range of beam apertures (1–25 cm). H(L) was evaluated using the dose integrals computed with the 90 cm long phantoms. The resultant H(L) data were subsequently used to compute the fraction of the total energy absorbed inside or outside the scan range (E{sub in}/E or E{sub out}/E) on the phantom central and peripheral axes, where E = LD{sub eq} was the total energy absorbed along the z axis. Results: The midpoint dose in the 60 cm long polyethylene phantom was equal to that in the 90 cm long polyethylene phantom. The short-to-long phantom dose

  2. Characterizing protein crystal nucleation

    NASA Astrophysics Data System (ADS)

    Akella, Sathish V.

    We developed an experimental microfluidic based technique to measure the nucleation rates and successfully applied the technique to measure nucleation rates of lysozyme crystals. The technique involves counting the number of samples which do not have crystals as a function of time. Under the assumption that nucleation is a Poisson process, the fraction of samples with no crystals decays exponentially with the decay constant proportional to nucleation rate and volume of the sample. Since nucleation is a random and rare event, one needs to perform measurements on large number of samples to obtain good statistics. Microfluidics offers the solution of producing large number of samples at minimal material consumption. Hence, we developed a microfluidic method and measured nucleation rates of lysozyme crystals in supersaturated protein drops, each with volume of ˜ 1 nL. Classical Nucleation Theory (CNT) describes the kinetics of nucleation and predicts the functional form of nucleation rate in terms of the thermodynamic quantities involved, such as supersaturation, temperature, etc. We analyzed the measured nucleation rates in the context of CNT and obtained the activation energy and the kinetic pre-factor characterizing the nucleation process. One conclusion is that heterogeneous nucleation dominates crystallization. We report preliminary studies on selective enhancement of nucleation in one of the crystal polymorprhs of lysozyme (spherulite) using amorphous mesoporous bioactive gel-glass te{naomi06, naomi08}, CaO.P 2O5.SiO2 (known as bio-glass) with 2-10 nm pore-size diameter distribution. The pores act as heterogeneous nucleation centers and claimed to enhance the nucleation rates by molecular confinement. The measured kinetic profiles of crystal fraction of spherulites indicate that the crystallization of spherulites may be proceeding via secondary nucleation pathways.

  3. High-purity germanium crystal growing

    SciTech Connect

    Hansen, W.L.; Haller, E.E.

    1982-10-01

    The germanium crystals used for the fabrication of nuclear radiation detectors are required to have a purity and crystalline perfection which is unsurpassed by any other solid material. These crystals should not have a net electrically active impurity concentration greater than 10/sup 10/cm/sup -3/ and be essentially free of charge trapping defects. Such perfect crystals of germanium can be grown only because of the highly favorable chemical and physical properties of this element. However, ten years of laboratory scale and commercial experience has still not made the production of such crystals routine. The origin and control of many impurities and electrically active defect complexes is now fairly well understood but regular production is often interrupted for long periods due to the difficulty of achieving the required high purity or to charge trapping in detectors made from crystals seemingly grown under the required conditions. The compromises involved in the selection of zone refining and crystal grower parts and ambients is discussed and the difficulty in controlling the purity of key elements in the process is emphasized. The consequences of growing in a hydrogen ambient are discussed in detail and it is shown how complexes of neutral defects produce electrically active centers.

  4. Angiographic Evaluation of Carotid Artery Grafting with Prefabricated Small-Diameter, Small-Intestinal Submucosa Grafts in Sheep

    SciTech Connect

    Pavcnik, Dusan; Obermiller, Josef; Uchida, Barry T.; Van Alstine, William; Edwards, James M.; Landry, Gregory J.; Kaufman, John A.; Keller, Frederick S.; Roesch, Josef

    2009-01-15

    The purpose of this study was to report the longitudinal angiographic evaluation of prefabricated lyophilized small-intestinal submucosa (SIS) grafts placed in ovine carotid arteries and to demonstrate a variety of complications that developed. A total of 24 grafts, 10 cm long and 6 mm in diameter, were placed surgically as interposition grafts. Graft patency at 1 week was evaluated by Doppler ultrasound, and angiography was used for follow-up at 1 month and at 3 to 4 months. A 90% patency rate was found at 1 week, 65% at 1 month, and 30% at 3 to 4 months. On the patent grafts, angiography demonstrated a variety of changes, such as anastomotic stenoses, graft diffuse dilations and dissections, and aneurysm formation. These findings have not been previously demonstrated angiographically by other investigators reporting results with small-diameter vessel grafts made from fresh small-intestinal submucosa (SIS). The complications found were partially related to the graft construction from four SIS layers. Detailed longitudinal angiographic study should become an essential part of any future evaluation of small-vessel SIS grafting.

  5. Selective Dispersion of Highly Pure Large-Diameter Semiconducting Carbon Nanotubes by a Flavin for Thin-Film Transistors.

    PubMed

    Park, Minsuk; Kim, Somin; Kwon, Hyeokjae; Hong, Sukhyun; Im, Seongil; Ju, Sang-Yong

    2016-09-01

    Scalable and simple methods for selective extraction of pure, semiconducting (s) single-walled carbon nanotubes (SWNTs) is of profound importance for electronic and photovoltaic applications. We report a new, one-step procedure to obtain respective large-diameter s- and metallic (m)-SWNT enrichment purity in excess of 99% and 78%, respectively, via interaction between the aromatic dispersing agent and SWNTs. The approach utilizes N-dodecyl isoalloxazine (FC12) as a surfactant in conjunction with sonication and benchtop centrifugation methods. After centrifugation, the supernatant is enriched in s-SWNTs with less carbonaceous impurities, whereas precipitate is enhanced in m-SWNTs. In addition, the use of an increased centrifugal force enhances both the purity and population of larger diameter s-SWNTs. Photoinduced energy transfer from FC12 to SWNTs is facilitated by respective electronic level alignment. Owing to its peculiar photoreduction capability, FC12 can be employed to precipitate SWNTs upon UV irradiation and observe absorption of higher optical transitions of SWNTs. A thin-film transistor prepared from a dispersion of enriched s-SWNTs was fabricated to verify electrical performance of the sorted sample and was observed to display p-type conductance with an average on/off ratio over 10(6) and an average mobility over 10 cm(2)/V·s. PMID:27538495

  6. Fiber diameter distributions in the chinchilla's ampullary nerves

    NASA Technical Reports Server (NTRS)

    Hoffman, Larry F.; Honrubia, Vicente

    2002-01-01

    A morphometric study of the chinchilla's ampullary nerves was conducted to produce an unbiased accounting of the diameter distribution of their constituent fibers. Diameter analyses were determined from 1 microm plastic-embedded nerve sections taken at a plane immediately proximal to the sensory epithelium. We found these nerves to be composed of 2094+/-573 fibers, having diameters that ranged from 0.5 to 8 microm. The distributions of diameters were positively skewed, where approximately 75% of the fibers were found to have diameters less than 3.5 microm. An analysis of the spatial distribution of diameters within the nerve section revealed that the lateralmost areas of the nerve contained larger fractions of fibers within the smallest diameter quintiles, and the central area harbored greater proportions of the larger diameter quintiles. However, significant fractions of all quintiles were found in all areas. These data were integrated with available data of Fernandez et al. (1998) to produce diameter estimates of calyx, dimorphic, and bouton morphology subpopulations. In view of a general relationship between diameter, innervation locus, and an afferent's physiologic characteristics, these data provide the basis for developing a perspective for the in situ distribution of afferent response dynamics.

  7. Crystal Systems.

    ERIC Educational Resources Information Center

    Schomaker, Verner; Lingafelter, E. C.

    1985-01-01

    Discusses characteristics of crystal systems, comparing (in table format) crystal systems with lattice types, number of restrictions, nature of the restrictions, and other lattices that can accidently show the same metrical symmetry. (JN)

  8. Optical, dielectric and microhardness studies on (100) directed ADP crystal.

    PubMed

    Rajesh, P; Ramasamy, P

    2009-09-15

    (100) directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The size of the grown crystal is 40 mm in diameter and 50mm in thickness. The grown crystals were characterized by UV-vis spectroscopy, Vickers hardness and dielectric studies. Comparing the (100) plane of the conventional method grown ADP crystal with (100) directed SR method grown ADP crystal, optical transparency, dielectric constant and Vickers hardness number are increased and dielectric loss is decreased in SR method grown crystal. PMID:19592298

  9. Catastrophes of large diameter pipelines. The role of hydrogen fields

    SciTech Connect

    Polyakov, V.N.

    1995-09-01

    Fracture statistics on transmission pipelines is presented. Fractures of large-diameter pipelines are regarded as catastrophes. Fracture accidents of other pipes are less dangerous. Hydrogen makes outer layers of pipes brittle. Therefore, critical crack lengths for pipes have been calculated by a linear fracture mechanics technique. It was found that a crack of any length may be critical. The opposite opinion on reliable operation of large-diameter pipes (diameter 1420 mm) is discussed.

  10. Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support

    NASA Astrophysics Data System (ADS)

    Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

    2013-06-01

    Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

  11. Wire diameter dependence in the catalytic decomposition of H2

    NASA Astrophysics Data System (ADS)

    Umemoto, Hironobu

    2014-01-01

    Jansen et al. have demonstrated that the dissociaiton rate of H2 molecules on hot wire surfaces, normalized per unit surface area, depends on the wire diameter based on the electrical power consumption measurements [J. Appl. Phys. 66, 5749 (1989)]. Mathematical modeling calculations have also been presented to support their experimental results. In the present paper, it is shown that such a wire diameter dependence cannot be observed and that the H-atom density normalized by the wire surface area depends little on the wire diameter. Modeling calculations also show that the wire diameter dependence of the dissociation rate cannot be expected under typical decomposition conditions.

  12. Objective Crystal Spectrometer on the SRG satellite

    NASA Astrophysics Data System (ADS)

    Christensen, Finn E.; Westergaard, N. J.; Rasmussen, Ib L.; Schnopper, Herbert W.; Wiebicke, Hans-Joachim; Halm, Ingolf; Geppert, U. R.; Borozdin, K. N.

    1994-11-01

    The flight version of the Objective Crystal Spectrometer (OXS) on the SPECTRUM-X- GAMMA satellite is presented. The spectrometer is a panel that is placed in front of one of the SODART telescopes. It is composed of an array of the three Bragg crystals, LiF(220), Si(111) and RAP(001) for high resolution spectroscopy in the energy bands that encompass the H- and He-like emission line features from the cosmically important elements Fe, S, Ar and O. An energy resolution (E/(Delta) E) of 1250 will be obtained for He-like Fe emission, > 3000 for He-like S and Ar, > 700 for He-like O. In addition, the Si crystals will be coated with a multilayer that will allow spectroscopy with an energy resolution of approximately 80 in the energy band immediately below the C-K absorption edge of 0.284 keV. All the flight crystals are available and detailed calibrations have been obtained for each crystal. They confirm our specifications for the overall performance of the OXS. An estimate of the effective area in the 4 energy windows that are available to OXS yields > 100 cm2 from 5 to 7.4 keV, > 200 cm2 from 2.3 to 4.6 keV, approximately 10 cm+2) from 0.55 to 0.81 keV and approximately 100 cm2 from 0.175 to 0.28 keV.

  13. Monomial Crystals and Partition Crystals

    NASA Astrophysics Data System (ADS)

    Tingley, Peter

    2010-04-01

    Recently Fayers introduced a large family of combinatorial realizations of the fundamental crystal B(Λ0) for ^sln, where the vertices are indexed by certain partitions. He showed that special cases of this construction agree with the Misra-Miwa realization and with Berg's ladder crystal. Here we show that another special case is naturally isomorphic to a realization using Nakajima's monomial crystal.

  14. Brain Arterial Diameters as a Risk Factor for Vascular Events

    PubMed Central

    Gutierrez, Jose; Cheung, Ken; Bagci, Ahmet; Rundek, Tatjana; Alperin, Noam; Sacco, Ralph L; Wright, Clinton B; Elkind, Mitchell S V

    2015-01-01

    Background Arterial luminal diameters are routinely used to assess for vascular disease. Although small diameters are typically considered pathological, arterial dilatation has also been associated with disease. We hypothesize that extreme arterial diameters are biomarkers of the risk of vascular events. Methods and Results Participants in the Northern Manhattan Study who had a time-of-flight magnetic resonance angiography were included in this analysis (N=1034). A global arterial Z-score, called the brain arterial remodeling (BAR) score, was obtained by averaging the measured diameters within each individual. Individuals with a BAR score <−2 SDs were considered to have the smallest diameters, individuals with a BAR score >−2 and <2 SDs had average diameters, and individuals with a BAR score >2 SDs had the largest diameters. All vascular events were recorded prospectively after the brain magnetic resonance imaging. Spline curves and incidence rates were used to test our hypothesis. The association of the BAR score with death (P=0.001), vascular death (P=0.02), any vascular event (P=0.05), and myocardial infarction (P=0.10) was U-shaped except for ischemic stroke (P=0.74). Consequently, incidence rates for death, vascular death, myocardial infarction, and any vascular event were higher in individuals with the largest diameters, whereas individuals with the smallest diameters had a higher incidence of death, vascular death, any vascular event, and ischemic stroke compared with individuals with average diameters. Conclusions The risk of death, vascular death, and any vascular event increased at both extremes of brain arterial diameters. The pathophysiology linking brain arterial remodeling to systemic vascular events needs further research. PMID:26251284

  15. Measurement of sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Weigand, A. J.; Mirtich, M. J.

    1975-01-01

    A study was undertaken to investigate the sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters. Quartz crystal microbalances and fused silica samples were used to analyze the sputtered flux. Spectral transmittance measurements and spectrographic analysis of the samples were made after they were exposed to different thruster effluence by operating the thrusters at various conditions and durations of time. These measurements were used to locate the source of the efflux and determine its accumulated effect at various locations near the thruster. Comparisons of in situ and ex situ transmittance measurements of samples exposed to thruster efflux are also presented.

  16. High spatial resolution gamma imaging detector based on a 5 inch diameter R3292 Hamamatsu PSPMT

    SciTech Connect

    Wojcik, R.; Majewski, S.; Kross, B.; Weisenberger, A.G.; Steinbach, D.

    1998-06-01

    High resolution imaging gamma-ray detectors were developed using Hamamatsu`s 5 inch diameter R3292 position sensitive PMT (PSPMT) and a variety of crystal scintillator arrays. Special readout techniques were used to maximize the active imaging area while reducing the number of readout channels. Spatial resolutions approaching 1 mm were obtained in a broad energy range from 20 to 511 keV. Results are also presented of coupling the scintillator arrays to the PMT via imaging light guides consisting of acrylic optical fibers.

  17. Photonic crystal microspheres

    NASA Astrophysics Data System (ADS)

    Zhokhov, A. A.; Masalov, V. M.; Sukhinina, N. S.; Matveev, D. V.; Dolganov, P. V.; Dolganov, V. K.; Emelchenko, G. A.

    2015-11-01

    Spherical samples of photonic crystals formed by colloidal SiO2 nanoparticles were synthesized. Synthesis of microspheres from 160 nm, 200 nm and 430 nm diameter colloidal nanoparticles was performed over a wide size range, from 5 μm to 50 μm. The mechanism of formation of void microparticles exceeding 50 μm is discussed. The spectral measurements verified the association of the spectra with the peaks of selective reflection from the cubic lattice planes. The microparticle morphology is characterized by scanning electron microscopy (SEM).

  18. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool.

    PubMed

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-12-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ's raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  19. Dataset for the validation and use of DiameterJ an open source nanofiber diameter measurement tool

    PubMed Central

    Hotaling, Nathan A.; Bharti, Kapil; Kriel, Haydn; Simon, Carl G.

    2015-01-01

    DiameterJ is an open source image analysis plugin for ImageJ. DiameterJ produces ten files for every image that it analyzes. These files include the images that were analyzed, the data to create histograms of fiber radius, pore size, fiber orientation, and summary statistics, as well as images to check the output of DiameterJ. DiameterJ was validated with 130 in silico-derived, digital, synthetic images and 24 scanning electron microscope (SEM) images of steel wire samples with a known diameter distribution. Once validated, DiameterJ was used to analyze SEM images of electrospun polymeric nanofibers, including a comparison of different segmentation algorithms. In this article, all digital synthetic images, SEM images, and their segmentations are included. Additionally, DiameterJ’s raw output files, and processed data is included for the reader. The data provided herein was used to generate the figures in DiameterJ: A Validated Open Source Nanofiber Diameter Measurement Tool[1], where more discussion can be found. PMID:26380840

  20. The Measurements of the Solar Diameter at the Kepler's Times

    NASA Astrophysics Data System (ADS)

    Sigismondi, Costantino; Fraschetti, Federico

    2002-12-01

    We examine five measurements of the solar disk diameter made with a pinhole instrument by Tycho in 1591 and Kepler in 1600-1602 [1]. Those are the first accurate measurements of the solar disk diameter available in literature, even if Ptolemy and Copernicus already did such measurements [2].

  1. Method accurately measures mean particle diameters of monodisperse polystyrene latexes

    NASA Technical Reports Server (NTRS)

    Kubitschek, H. E.

    1967-01-01

    Photomicrographic method determines mean particle diameters of monodisperse polystyrene latexes. Many diameters are measured simultaneously by measuring row lengths of particles in a triangular array at a glass-oil interface. The method provides size standards for electronic particle counters and prevents distortions, softening, and flattening.

  2. Periodically Diameter-Modulated Semiconductor Nanowires for Enhanced Optical Absorption.

    PubMed

    Ko, Minjee; Baek, Seong-Ho; Song, Bokyung; Kang, Jang-Won; Kim, Shin-Ae; Cho, Chang-Hee

    2016-04-01

    A diameter-modulated silicon nanowire array to enhance the optical absorption across broad spectral range is presented. Periodic shape engineering is achieved using conventional semiconductor processes and the unique optical properties are analyzed. The periodicity in the diameter of the silicon nanowires enables stronger and more closely spaced optical resonances, leading to broadband absorption enhancement. PMID:26833855

  3. Reliable Diameter Control of Carbon Nanotube Nanobundles Using Withdrawal Velocity.

    PubMed

    Shin, Jung Hwal; Kim, Kanghyun; An, Taechang; Choi, WooSeok; Lim, Geunbae

    2016-12-01

    Carbon nanotube (CNT) nanobundles are widely used in nanoscale imaging, fabrication, and electrochemical and biological sensing. The diameter of CNT nanobundles should be controlled precisely, because it is an important factor in determining electrode performance. Here, we fabricated CNT nanobundles on tungsten tips using dielectrophoresis (DEP) force and controlled their diameters by varying the withdrawal velocity of the tungsten tips. Withdrawal velocity pulling away from the liquid-air interface could be an important, reliable parameter to control the diameter of CNT nanobundles. The withdrawal velocity was controlled automatically and precisely with a one-dimensional motorized stage. The effect of the withdrawal velocity on the diameter of CNT nanobundles was analyzed theoretically and compared with the experimental results. Based on the attachment efficiency, the withdrawal velocity is inversely proportional to the diameter of the CNT nanobundles; this has been demonstrated experimentally. Control of the withdrawal velocity will play an important role in fabricating CNT nanobundles using DEP phenomena. PMID:27581602

  4. Crystal Shape Evolution in Detached Bridgman Growth

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.

    2013-01-01

    Detached (or dewetted) Bridgman crystal growth defines that process in which a gap exists between a growing crystal and the crucible wall. Existence of the gap provides several advantages, including no sticking of the crystal to the crucible wall, reduced thermal and mechanical stresses, reduced dislocations, and no heterogeneous nucleation by the crucible. Numerical calculations are used to determine the conditions in which a gap can exist. According to crystal shape stability theory, only some of these gap widths will be dynamically stable. Beginning with a crystal diameter that differs from stable conditions, the transient crystal growth process is analyzed. In microgravity, dynamic stability depends only on capillary effects and is decoupled from heat transfer. Depending on the initial conditions and growth parameters, the crystal shape will evolve towards the crucible wall, towards a stable gap width, or towards the center of the crucible, collapsing the meniscus. The effect of a tapered crucible on dynamic stability is also described.

  5. Crystal Shape Evolution in Detached Bridgman Growth

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.

    2013-01-01

    Detached (or dewetted) Bridgman crystal growth defines that process in which a gap exists between a growing crystal and the crucible wall. Existence of the gap provides several advantages, including no sticking of the crystal to the crucible wall, reduced thermal and mechanical stresses, reduced dislocations, and no heterogeneous nucleation by the crucible. Numerical calculations are used to determine the conditions in which a gap can exist. According to crystal shape stability theory, only some of these gap widths will be dynamically stable. Beginning with a crystal diameter that differs from stable conditions, the transient crystal growth process is analyzed. In microgravity, dynamic stability depends only on capillary effects and is decoupled from heat transfer. Depending on the initial conditions and growth parameters, the crystal shape will evolve towards the crucible wall, towards a stable gap width, or towards the center of the crucible, collapsing the meniscus. The effect of a tapered crucible on dynamic stability is also described

  6. Lysozyme Crystal

    NASA Technical Reports Server (NTRS)

    2004-01-01

    To the crystallographer, this may not be a diamond but it is just as priceless. A Lysozyme crystal grown in orbit looks great under a microscope, but the real test is X-ray crystallography. The colors are caused by polarizing filters. Proteins can form crystals generated by rows and columns of molecules that form up like soldiers on a parade ground. Shining X-rays through a crystal will produce a pattern of dots that can be decoded to reveal the arrangement of the atoms in the molecules making up the crystal. Like the troops in formation, uniformity and order are everything in X-ray crystallography. X-rays have much shorter wavelengths than visible light, so the best looking crystals under the microscope won't necessarily pass muster under the X-rays. In order to have crystals to use for X-ray diffraction studies, crystals need to be fairly large and well ordered. Scientists also need lots of crystals since exposure to air, the process of X-raying them, and other factors destroy them. Growing protein crystals in space has yielded striking results. Lysozyme's structure is well known and it has become a standard in many crystallization studies on Earth and in space.

  7. Femoral head diameter considerations for primary total hip arthroplasty.

    PubMed

    Girard, J

    2015-02-01

    The configuration of total hip arthroplasty (THA) implants has constantly evolved since they were first introduced. One of the key components of THA design is the diameter of the prosthetic femoral head. It has been well established that the risk of dislocation is lower as the head diameter increases. But head diameter impacts other variables beyond joint stability: wear, cam-type impingement, range of motion, restoration of biomechanics, proprioception and groin pain. The introduction of highly cross-linked polyethylene and hard-on-hard bearings has allowed surgeons to implant large-diameter heads that almost completely eliminate the risk of dislocation. But as a result, cup liners have become thinner. With femoral head diameters up to 36 mm, the improvement in joint range of motion, delay in cam-type impingement and reduction in dislocation risk have been clearly demonstrated. Conversely, large-diameter heads do not provide any additional improvements. If an "ecologically sound" approach to hip replacement is embraced (e.g. keeping the native femoral head diameter), hip resurfacing with a metal-on-metal bearing must be carried out. The reliability of large-diameter femoral heads in the longer term is questionable. Large-diameter ceramic-on-ceramic bearings may be plagued by the same problems as metal-on-metal bearings: groin pain, squeaking, increased stiffness, irregular lubrication, acetabular loosening and notable friction at the Morse taper. These possibilities require us to be extra careful when using femoral heads with a diameter greater than 36 mm. PMID:25596984

  8. Pupil Diameter Changes in High Myopes after Collamer Lens Implantation

    PubMed Central

    Li, Dan; Yang, Yabo; Su, Caipei; Yin, Houfa; Liu, Xue

    2015-01-01

    ABSTRACT Purpose To observe the changes in pupil size under photopic and scotopic conditions after Implantable Collamer Lens (ICL) implantations in eyes with high myopia. Methods The ICL was implanted in 90 eyes belonging to 45 patients with high myopia. Photopic pupil diameters, scotopic pupil diameters, anterior chamber depths, and ICL vaults were examined at the preoperative, postoperative 1-month, and postoperative 3-month stages. The preoperative and postoperative photopic pupil diameters and scotopic pupil diameters were also compared with each other to note the differences between them. The correlations between preoperative and postoperative pupil diameter changes under different light conditions and presurgical refractive error were analyzed alongside patient’s age and ICL vault. Results Pupil diameters at both postoperative 1-month and postoperative 3-month stages were smaller than those before operation in distinct light environments, as well as pupil constriction amplitude. Correlation analysis showed that there was a statistically significant correlation between pupil diameter changes under different light conditions and presurgical refractive error at 1 month and 3 months after ICL implantation; pupil diameter decreased more when presurgical refractive error powers were less myopic. Statistically significant correlations were not found, however, with patient’s age and ICL vault. Postoperative 1-month and mean postoperative 3-month anterior chamber depths were decreased when compared with preoperative anterior chamber depths. Statistically significant correlations were found in change in preoperative and postoperative anterior chamber depth and ICL vault. No statistically significant difference was found between ICL vault at the postoperative 1-month and postoperative 3-month stages. Conclusions Pupil diameter may decrease at the 1- and 3-month stages after ICL implantation under both photopic and scotopic conditions. This indicates that reduction

  9. PREPARATION OF REFRACTORY OXIDE CRYSTALS

    DOEpatents

    Grimes, W.R.; Shaffer, J.H.; Watson, G.M.

    1962-11-13

    A method is given for preparing uranium dioxide, thorium oxide, and beryllium oxide in the form of enlarged individual crystals. The surface of a fused alkali metal halide melt containing dissolved uranium, thorium, or beryllium values is contacted with a water-vapor-bearing inert gas stream at a rate of 5 to 10 cubic centimeters per minute per square centimeter of melt surface area. Growth of individual crystals is obtained by prolonged contact. Beryllium oxide-coated uranium dioxide crystals are prepared by disposing uranium dioxide crystals 5 to 20 microns in diameter in a beryllium-containing melt and contacting the melt with a water-vapor-bearing inert gas stream in the same manner. (AEC)

  10. Optics of globular photonic crystals

    SciTech Connect

    Gorelik, V S

    2007-05-31

    The results of experimental and theoretical studies of the optical properties of globular photonic crystals - new physical objects having a crystal structure with the lattice period exceeding considerably the atomic size, are presented. As globular photonic crystals, artificial opal matrices consisting of close-packed silica globules of diameter {approx}200 nm were used. The reflection spectra of these objects characterising the parameters of photonic bands existing in these crystals in the visible spectral region are presented. The idealised models of the energy band structure of photonic crystals investigated in the review give analytic dispersion dependences for the group velocity and the effective photon mass in a globular photonic crystal. The characteristics of secondary emission excited in globular photonic crystals by monochromatic and broadband radiation are presented. The results of investigations of single-photon-excited delayed scattering of light observed in globular photonic crystals exposed to cw UV radiation and radiation from a repetitively pulsed copper vapour laser are presented. The possibilities of using globular photonic crystals as active media for lasing in different spectral regions are considered. It is proposed to use globular photonic crystals as sensitive sensors in optoelectronic devices for molecular analysis of organic and inorganic materials by the modern methods of laser spectroscopy. The results of experimental studies of spontaneous and stimulated globular scattering of light are discussed. The conditions for observing resonance and two-photon-excited delayed scattering of light are found. The possibility of accumulation and localisation of the laser radiation energy inside a globular photonic crystal is reported. (review)

  11. RNA Crystallization

    NASA Technical Reports Server (NTRS)

    Golden, Barbara L.; Kundrot, Craig E.

    2003-01-01

    RNA molecules may be crystallized using variations of the methods developed for protein crystallography. As the technology has become available to syntheisize and purify RNA molecules in the quantities and with the quality that is required for crystallography, the field of RNA structure has exploded. The first consideration when crystallizing an RNA is the sequence, which may be varied in a rational way to enhance crystallizability or prevent formation of alternate structures. Once a sequence has been designed, the RNA may be synthesized chemically by solid-state synthesis, or it may be produced enzymatically using RNA polymerase and an appropriate DNA template. Purification of milligram quantities of RNA can be accomplished by HPLC or gel electrophoresis. As with proteins, crystallization of RNA is usually accomplished by vapor diffusion techniques. There are several considerations that are either unique to RNA crystallization or more important for RNA crystallization. Techniques for design, synthesis, purification, and crystallization of RNAs will be reviewed here.

  12. Protein Crystallization

    NASA Technical Reports Server (NTRS)

    Chernov, Alexander A.

    2005-01-01

    Nucleation, growth and perfection of protein crystals will be overviewed along with crystal mechanical properties. The knowledge is based on experiments using optical and force crystals behave similar to inorganic crystals, though with a difference in orders of magnitude in growing parameters. For example, the low incorporation rate of large biomolecules requires up to 100 times larger supersaturation to grow protein, rather than inorganic crystals. Nucleation is often poorly reproducible, partly because of turbulence accompanying the mixing of precipitant with protein solution. Light scattering reveals fluctuations of molecular cluster size, its growth, surface energies and increased clustering as protein ages. Growth most often occurs layer-by-layer resulting in faceted crystals. New molecular layer on crystal face is terminated by a step where molecular incorporation occurs. Quantitative data on the incorporation rate will be discussed. Rounded crystals with molecularly disordered interfaces will be explained. Defects in crystals compromise the x-ray diffraction resolution crucially needed to find the 3D atomic structure of biomolecules. The defects are immobile so that birth defects stay forever. All lattice defects known for inorganics are revealed in protein crystals. Contribution of molecular conformations to lattice disorder is important, but not studied. This contribution may be enhanced by stress field from other defects. Homologous impurities (e.g., dimers, acetylated molecules) are trapped more willingly by a growing crystal than foreign protein impurities. The trapped impurities induce internal stress eliminated in crystals exceeding a critical size (part of mni for ferritin, lysozyme). Lesser impurities are trapped from stagnant, as compared to the flowing, solution. Freezing may induce much more defects unless quickly amorphysizing intracrystalline water.

  13. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.; Higgins, Andrew J.

    2006-07-01

    The critical diameter and failure thickness of both neat liquid nitromethane and a 65% nitromethane/35% nitroethane blend confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism of detonation in these explosives. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from expansion losses (wave curvature), then it is expected that the failure thickness should be half the value of the critical diameter. The critical diameter and failure thickness of neat nitromethane confined in aluminum are found to be 2.5 mm and 0.75 mm respectively for a temperature range of 26 ± 1°C. The critical diameter and failure thickness of the 65NM/35NE blend confined in aluminum are found to be 6.2 mm and 1.7 mm respectively for a temperature range of 28 ± 1°C. The ratio of critical diameter to failure thickness for these experiments is found to lie between 3:1 and 4:1 rather than 2:1 as expected from wave curvature theory. By comparing the experimentally determined values of critical diameter and thickness for the test explosives and examining the failure patterns recovered on witness plates, a mechanism of propagation in thin rectangular channels is proposed based on complex wave interactions.

  14. Sterilization of various diameter dead-ended tubes.

    PubMed

    Young, J H

    1993-06-01

    Effect of tube diameter on steam-in-place sterilization of dead-ended tubes was studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Time required for sterilization was determined for 9.4-cm-long tubes with various inside diameters from 0.4 to 1.7 cm. Sterilization time increased with decreasing tube diameter. Experimentally measured kill kinetics in 1.7-cm tubes were in agreement with those predicted if measured temperatures represented saturated steam. A 12-log spore reduction was achieved in 1.7-cm diameter vertical and horizontal tubes in less than 63 minutes. For smaller diameter tubes, entrapped air remained after 2 hours and rates of kill were very dependent on position within the tube, tube diameter, and tube orientation with respect to the gravitational vector. Times to achieve a 1-log drop in spore population in the smaller tubes were as much as 10 times greater than those expected if measured temperatures represented saturated steam. Sterilization was not achieved throughout the 0.4-cm tubes. Recommendations are made for including steam bleeders or using prevaccum cycles for these smaller diameter tubes. PMID:18609656

  15. Computational crystallization.

    PubMed

    Altan, Irem; Charbonneau, Patrick; Snell, Edward H

    2016-07-15

    Crystallization is a key step in macromolecular structure determination by crystallography. While a robust theoretical treatment of the process is available, due to the complexity of the system, the experimental process is still largely one of trial and error. In this article, efforts in the field are discussed together with a theoretical underpinning using a solubility phase diagram. Prior knowledge has been used to develop tools that computationally predict the crystallization outcome and define mutational approaches that enhance the likelihood of crystallization. For the most part these tools are based on binary outcomes (crystal or no crystal), and the full information contained in an assembly of crystallization screening experiments is lost. The potential of this additional information is illustrated by examples where new biological knowledge can be obtained and where a target can be sub-categorized to predict which class of reagents provides the crystallization driving force. Computational analysis of crystallization requires complete and correctly formatted data. While massive crystallization screening efforts are under way, the data available from many of these studies are sparse. The potential for this data and the steps needed to realize this potential are discussed. PMID:26792536

  16. Measurements of high number densities of ice crystals in the tops of tropical cumulonimbus

    NASA Astrophysics Data System (ADS)

    Knollenberg, R. G.; Kelly, K.; Wilson, J. C.

    1993-05-01

    Imaging and light scattering instruments were used during the January/February 1987 STEP Tropical Experiment at Darwin, Australia, to measure ice crystal size distributions in the tops of tropical cumulonimbus anvils associated with tropical cyclones and related cloud systems. Two light scattering instruments covered particles from 0.1-μm to 78-μm diameter. Particles larger than 50-μm diameter were imaged with a two-dimensional Grey optical array imaging probe. The measurements were made at altitudes ranging from 13 to 18 km at temperatures ranging from -60° to -90°C. Additional measurements made in continental cumulonimbus anvils in the western United States offer a comparative data set. The tropical anvil penetrations revealed surprisingly high concentrations of ice crystals. Number densities were typically greater than 10 cm-3 with up to 100 cm-3 if one includes all particles larger than 0.1 μm and can approach condensation nuclei in total concentration. In order to explain the high number densities, ice crystal nucleation at altitude is proposed with the freezing of fairly concentrated solution droplets in equilibrium at low relative humidities. Any dilute liquid phase is hypothesized to be transitory with a vanishingly short lifetime and limited to cloud levels nearer -40°C. Homogeneous nucleation of ice involving H2SO4 nuclei is attractive in explaining the high number densities of small ice crystals observed near cloud top at temperatures below -60°C. The tropical size distributions were converted to mass using a spherical equivalent size, while the continental anvil data were treated as crystalline plates. Comparisons of the ice water contents integrated from the mass distributions with total water contents measured with NOAA Lyman-alpha instruments require bulk densities equivalent to solid ice for best agreement. Correlation between the two data sets for a number of flight passes was quite good and was further improved by subtraction of water

  17. Effects of diameter and temperature on XTX-8004 detonation velocity

    SciTech Connect

    Campos, C.A.

    1980-10-01

    This study was performed to determine the dependence of XTX-8004 steady detonation velocity on charge diameter and temperature. The tests were performed for four different diameters at three temperatures using a standard 4-track detonation velocity block and corresponding printed circuit ionization switch plate. The explosive was loaded in the detonation velocity block to a nominal density of 1.553 g/cc. Measurements obtained from two samples per temperature indicate the critical diameter is less than 0.178 cm. A relationship between detonation velocity and density due to temperature was established using experimental measurements.

  18. Calibration of the radiometric asteroid scale using occultation diameters

    NASA Technical Reports Server (NTRS)

    Telesco, C. M.; Brunk, W. E.; Brown, R. H.; Morrison, D.

    1982-01-01

    The paper describes a new approach to the calibration of the radiometric asteroid scale, which relies on recent accurate occultation measurements of the diameters of 2 Pallas (Wasserman et al., 1979) and 3 Juno (Millis et al., 1981), and the Voyager diameter of J4 Callisto, as well as IR photometry of these objects obtained with the NASA 3-m Infrared Telescope Facility. It is shown that this calibration is internally consistent to better than 5%, and probably has an absolute accuracy of + or - 5%. It is noted that a revision of the TRIAD radiometric diameters downward is required to bring them into agreement with the new calibration.

  19. Thermal mechanical analyses of large diameter ion accelerator systems

    SciTech Connect

    Brophy, J.R.; Aston, G.

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size. 8 refs.

  20. Thermal mechanical analyses of large diameter ion accelerator systems

    NASA Technical Reports Server (NTRS)

    Brophy, John R.; Aston, Graeme

    1989-01-01

    Thermal mechanical analyses of large diameter ion accelerator systems are performed using commercially available finite element software executed on a desktop computer. Finite element models of a 30-cm-diameter accelerator system formulated using plate/shell elements give calculated results which agree well with similar published obtained on a mainframe computer. Analyses of a 50-cm-diameter, three-grid accelerator system using measured grid temperatures (corresponding to discharge powers of 653 and 886 watts) indicate that thermally induced grid movements need not be the performance limiting phenomena for accelerator systems of this size.

  1. Comparison of Failure Thickness and Critical Diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Petel, Oren E.

    2005-07-01

    The critical diameter and failure thickness of liquid nitromethane confined by aluminum are determined experimentally. A comparison of these two parameters provides insight into the failure mechanism in nitromethane. If the failure of detonation in a critical charge diameter (or thickness) experiment is due to reaction quenching resulting from wave curvature, then it is expected that the critical diameter should be half the value of the critical thickness.[1] This has been shown to be the case with gas-phase detonations with nearly laminar reaction zones.[2] By comparing the experimentally determined values of critical diameter and thickness for a homogeneous liquid explosive, the validity of this model of detonation failure can be assessed. References: 1. Ramsay, J.B., 8th Symp. (Int.) on Detonation., 372-379 (1985). 2. Radulescu, M., Lee, J.H.S., Comb. and Flame, 131:29-46 (2002).

  2. SMALL DIAMETER STENCILING, ROLLING OVER STAMP. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER STENCILING, ROLLING OVER STAMP. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  3. Wavelength dependence of the apparent diameter of retinal blood vessels.

    PubMed

    Park, Robert; Twietmeyer, Karen; Chipman, Russell; Beaudry, Neil; Salyer, David

    2005-04-01

    Imaging of retinal blood vessels may assist in the diagnosis and monitoring of diseases such as glaucoma, diabetic retinopathy, and hypertension. However, close examination reveals that the contrast and apparent diameter of vessels are dependent on the wavelength of the illuminating light. In this study multispectral images of large arteries and veins within enucleated swine eyes are obtained with a modified fundus camera by use of intravitreal illumination. The diameters of selected vessels are measured as a function of wavelength by cross-sectional analysis. A fixed scale with spectrally independent dimension is placed above the retina to isolate the chromatic effects of the imaging system and eye. Significant apparent differences between arterial and venous diameters are found, with larger diameters observed at shorter wavelengths. These differences are due primarily to spectral absorption in the cylindrical blood column. PMID:15813519

  4. Optimal electrode diameter in relation to volume of the cochlea.

    PubMed

    Gnansia, D; Demarcy, T; Vandersteen, C; Raffaelli, C; Guevara, N; Delingette, H; Ayache, N

    2016-06-01

    The volume of the cochlea is a key parameter for electrode-array design. Indeed, it constrains the diameter of the electrode-array for low-traumatic positioning in the scala timpani. The present report shows a model of scala timpani volume extraction from temporal bones images in order to estimate a maximum diameter of an electrode-array. Nine temporal bones were used, and passed to high-resolution computed tomography scan. Using image-processing techniques, scala timpani were extracted from images, and cross-section areas were estimated along cochlear turns. Cochlear implant electrode-array was fitted in these cross-sections. Results show that the electrode-array diameter is small enough to fit in the scala timpani, however the diameter is restricted at the apical part. PMID:27246746

  5. Anomalous dependence of band gaps of binary nanotubes on diameters

    NASA Astrophysics Data System (ADS)

    Adhikari, Kapil; Huda, Muhammad; Ray, Asok

    2012-02-01

    Using cluster approximation, AlN, BN, GaN, SiGe, SiC, and GeC armchair type 1 nanotubes have been spin optimized using the hybrid functional B3LYP, a double ζ basis set and the GAUSSIAN 03 software. The electronic structures of group III nitride and group IV-IV nanotubes indicate that the band gap increases with tube diameter contrary to behavior expected from quantum size effects. A detailed study indicates that, in a class of binary nanotubes with partial ionic contributions in the bonds, for example, AlN, BN, GaN, GeC, and SiC, ionicity of the bonds decreases as diameter decreases due to increased sp^3 contribution. This causes the band gap to increase with diameter. But in nanotubes with covalent bonding, for example SiGe, the gap decreases with diameter. A general trend for a class of binary nanotubes is established.

  6. SMALL DIAMETER GRAVITY SEWERS: AN ALTERNATIVE FOR UNSEWERED COMMUNITIES

    EPA Science Inventory

    The most recently introduced wastewater collection alternative for small unsewered communities is septic tank effluent drains or small diameter gravity sewers (SDGS). Unlike conventional sewers, SDGS only collect settled wastewater. Grit, grease and other troublesome solids which...

  7. SMALL DIAMETER CEMENT LINING FROM STAIRWAY. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER CEMENT LINING FROM STAIRWAY. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  8. SMALL DIAMETER PRECEMENT LINING FROM CATWALK ABOVE. United States ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER PRE-CEMENT LINING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  9. Northern view of inside diameter welding station of the saw ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Northern view of inside diameter welding station of the saw line in bay9 of the main pipe mill building. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  10. Pupil diameter reflects uncertainty in attentional selection during visual search

    PubMed Central

    Geng, Joy J.; Blumenfeld, Zachary; Tyson, Terence L.; Minzenberg, Michael J.

    2015-01-01

    Pupil diameter has long been used as a metric of cognitive processing. However, recent advances suggest that the cognitive sources of change in pupil size may reflect LC-NE function and the calculation of unexpected uncertainty in decision processes (Aston-Jones and Cohen, 2005; Yu and Dayan, 2005). In the current experiments, we explored the role of uncertainty in attentional selection on task-evoked changes in pupil diameter during visual search. We found that task-evoked changes in pupil diameter were related to uncertainty during attentional selection as measured by reaction time (RT) and performance accuracy (Experiments 1-2). Control analyses demonstrated that the results are unlikely to be due to error monitoring or response uncertainty. Our results suggest that pupil diameter can be used as an implicit metric of uncertainty in ongoing attentional selection requiring effortful control processes. PMID:26300759

  11. SMALL DIAMETER PAINTING FROM CATWALK ABOVE. United States Pipe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    SMALL DIAMETER PAINTING FROM CATWALK ABOVE. - United States Pipe & Foundry Company Plant, Coating, Painting, Lining & Packaging Building, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL

  12. Development of welded metal bellows having minimum effective diameter change

    NASA Technical Reports Server (NTRS)

    Henschel, J. K.; Stevens, J. B.; Harvey, A. C.; Howland, J. S.; Rhee, S. S.

    1972-01-01

    A program of analysis, design, and fabrication was conducted to develop welded metal bellows having a minimum change in effective diameter for cryogenic turbomachinery face seal applications. Linear analysis of the principle types of bellows provided identification of concepts capable of meeting basic operation requirements. For the 6-inch (.152 m) mean diameter, 1.5-inch free length bellows studied, nonlinear analysis showed that opposed and nested toroidal bellows plates stiffened by means of alternating stiffener rings were capable of maintaining constant effective diameter within 0.3% and 0.1% respectively under the operating conditions of interest. Changes in effective diameter were due principally to bellows axial deflection with pressure differential having a lesser influence. Fabrication problems associated with joining the thin bellows plates to the relatively heavy stiffener rings were encountered and precluded assembly and testing of a bellows core. Fabrication problems are summarized and recommended fabrication methods for future effort are presented.

  13. Eddy sensors for small diameter stainless steel tubes.

    SciTech Connect

    Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

    2011-08-01

    The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

  14. Viscous flow and crystallization behavior of tektite glasses

    NASA Technical Reports Server (NTRS)

    Klein, L. C.; Yinnon, H.; Uhlmann, D. R.

    1980-01-01

    The variation of viscosity with temperature was determined in the 200-2000 K range for a Muong Nong tektite material. The viscosity at the liquidus temperature of 1320 C is 20,000 P; treatments between 900 and 1300 C do not result in significant crystallization in the natural sample except when the sample is heated in contact with a synthetic tektite composition. Two synthetic microtektite with lower SiO2 contents than the Muong Nong material were also examined; heat flow calculations were performed for 2.5 to 10 cm spheres of tektite when cooling by radiation.

  15. Crystal Data

    National Institute of Standards and Technology Data Gateway

    SRD 3 NIST Crystal Data (PC database for purchase)   NIST Crystal Data contains chemical, physical, and crystallographic information useful to characterize more than 237,671 inorganic and organic crystalline materials. The data include the standard cell parameters, cell volume, space group number and symbol, calculated density, chemical formula, chemical name, and classification by chemical type.

  16. Acoustic fill factors for a 120 inch diameter fairing

    NASA Technical Reports Server (NTRS)

    Lee, Y. Albert

    1992-01-01

    Data from the acoustic test of a 120-inch diameter payload fairing were collected and an analysis of acoustic fill factors were performed. Correction factors for obtaining a weighted spatial average of the interior sound pressure level (SPL) were derived based on this database and a normalized 200-inch diameter fairing database. The weighted fill factors were determined and compared with statistical energy analysis (VAPEPS code) derived fill factors. The comparison is found to be reasonable.

  17. Thermal resistance of ultra-small-diameter disk microlasers

    SciTech Connect

    Zhukov, A. E. Kryzhanovskaya, N. V.; Maximov, M. V.; Lipovskii, A. A.; Savelyev, A. V.; Shostak, I. I.; Moiseev, E. I.; Kudashova, Yu. V.; Kulagina, M. M.; Troshkov, S. I.

    2015-05-15

    The thermal resistance of AlGaAs/GaAs microlasers of the suspended-disk type with a diameter of 1.7–4 μm and InAs/InGaAs quantum dots in the active region is inversely proportional to the squared diameter of the microdisk. The proportionality factor is 3.2 × 10{sup −3} (K cm{sup 2})/W, and the thermal resistance is 120–20°C/mW.

  18. Understanding the effect of carbon status on stem diameter variations

    PubMed Central

    De Swaef, Tom; Driever, Steven M.; Van Meulebroek, Lieven; Vanhaecke, Lynn; Marcelis, Leo F. M.; Steppe, Kathy

    2013-01-01

    Background Carbon assimilation and leaf-to-fruit sugar transport are, along with plant water status, the driving mechanisms for fruit growth. An integrated comprehension of the plant water and carbon relationships is therefore essential to better understand water and dry matter accumulation. Variations in stem diameter result from an integrated response to plant water and carbon status and are as such a valuable source of information. Methods A mechanistic water flow and storage model was used to relate variations in stem diameter to phloem sugar loading and sugar concentration dynamics in tomato. The simulation results were compared with an independent model, simulating phloem sucrose loading at the leaf level based on photosynthesis and sugar metabolism kinetics and enabled a mechanistic interpretation of the ‘one common assimilate pool’ concept for tomato. Key Results Combining stem diameter variation measurements and mechanistic modelling allowed us to distinguish instantaneous dynamics in the plant water relations and gradual variations in plant carbon status. Additionally, the model combined with stem diameter measurements enabled prediction of dynamic variables which are difficult to measure in a continuous and non-destructive way, such as xylem water potential and phloem hydrostatic potential. Finally, dynamics in phloem sugar loading and sugar concentration were distilled from stem diameter variations. Conclusions Stem diameter variations, when used in mechanistic models, have great potential to continuously monitor and interpret plant water and carbon relations under natural growing conditions. PMID:23186836

  19. Nanofiber diameter-dependent MAPK activity in osteoblasts.

    PubMed

    Jaiswal, Devina; Brown, Justin L

    2012-11-01

    The major challenge for bone tissue engineering lies in the fabrication of scaffolds that can mimic the extracellular matrix and promote osteogenesis. Electrospun fibers are being widely researched for this application due to high porosity, interconnectivity, and mechanical strength of the fibrous scaffolds. Electrospun poly methyl methacrylate (PMMA, 2.416 ± 0.100 μm) fibers were fabricated and etched using a 60% propylene glycol methyl ether acetate (PGMEA)/limonene (vol/vol) solution to obtain fiber diameters ranging from 2.5 to 0.5 μm in a time-dependent manner. The morphology of the fibrous scaffolds was evaluated using scanning electron microscopy and cellular compatibility with etchant-treated scaffold was assessed using immunoflurescence. Mitogen-activated protein kinases (MAPK) activation in response to different fiber diameter was evaluated with western blot as well as quantitative in-cell western. We report that electrospun micro-fibers can be etched to 0.552 ± 0.047 μm diameter without producing beads. Osteoblasts adhered to the fibers and a change in fiber diameter played a major role in modulating the activation of extracellular signal-regulated kinase (ERK) and p38 kinases with 0.882 ± 0.091 μm diameter fibers producing an inverse effect on ERK and p38 phosphorylation. These results indicate that nanofibers produced by wet etching can be effectively utilized to produce diameters that can differentially modulate MAPK activation patterns. PMID:22700490

  20. Predicting Hamstring Graft Diameter Using MRI and Anthropometry

    PubMed Central

    Fritsch, Brett A; Mhaskar, Vikram A; An, Vincent Vinh Gia; Scholes, Corey

    2016-01-01

    Objectives: Graft diameter is one variable that may affect outcome of ACL reconstruction. The ability to predict the size of a graft in a given patient pre-operatively may help guide graft selection and preparation technique. Various papers have correlated anthropometric data and MRI tendon measurements to intraoperative graft diameter, although no papers have investigated these together. The intra-operative diameter of a hamstring autograft will be influenced by graft preparation technique. Our study aimed to investigate the prediction of intraoperative graft diameter of 2 different graft construct techniques (4-strand semitendinosus versus quadrupled semitendinosus) using anthropometry and MRI measurements. Methods: Retrospective review of two groups of ACL reconstruction using different graft preparation techniques was performed. “Conventional” 4-strand gracilis + semitendinosus with fixed suspension at the femur and screw fixation at the tibia were compared with quadrupled semitendinosus grafts with adjustable suspensory fixation at each end (Graftlink). Cross-sectional areas (XSA) of the semitendinosus and gracilis tendons was measured in the axial slice of a T2 weighted MRI image using a region-of-interest tool. Stepwise linear regression using intraoperative graft diameter as the dependant variable was performed using MRI XSA of the semitendinosus and gracilis tendons, gender and height as predictors. Results: 129 ACL Reconstruction in 127 patients were done in the time period, 89 of which were done conventionally, and 40 which employed the Graftlink construct. The median graft diameter in the Graftlink group (8.5mm IQR8-9) was greater than that of the conventional group (8mm, IQR 7.5-8) (p < 0.001). MRI XSA of semitendinosus and height were statistically significant predictors of diameter in the Graftlink group (R2 = 51%), whilst MRI XSA of semitendinosus + gracilis and gender were predictors in the conventional group (R2 = 36%). Conclusion: Graftlink

  1. Gold nanoparticle capture within protein crystal scaffolds.

    PubMed

    Kowalski, Ann E; Huber, Thaddaus R; Ni, Thomas W; Hartje, Luke F; Appel, Karina L; Yost, Jarad W; Ackerson, Christopher J; Snow, Christopher D

    2016-07-01

    DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)∼17 (nitrilotriacetic acid)∼1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was confirmed by single crystal X-ray crystallography. PMID:27264210

  2. Large Diameter, Radiative Extinction Experiments with Decane Droplets in Microgravity

    NASA Technical Reports Server (NTRS)

    Easton, John; Tien, James; Dietrich, Daniel

    1999-01-01

    The extinction of a diffusion flame is of fundamental interest in combustion science. Linan, Law, and Chung and Law analytically and experimentally determined an extinction boundary in terms of droplet diameter and pressure for a single droplet due to Damkohler, or blowoff, extinction. More recently, other researchers demonstrated extinction due to finite rate kinetics in reduced gravity for free droplets of heptane. Chao modeled the effect of radiative heat loss on a quasi-steady spherically symmetric single droplet burning in the absence of buoyancy. They determined that for increasing droplet diameter, a second limit can be reached such that combustion is no longer possible. This second, larger droplet diameter limit arises due to radiative heat loss, which increases with increasing droplet and flame diameter. This increase in radiative heat loss arises due to an increase in the surface area of the flame. Recently, Marchese modeled fuel droplets with detailed chemistry and radiative effects, and compared the results to other work. The modeling also showed the importance of radiative loss and radiative extinction Experiments examined the behavior of a large droplet of decane burning in reduced gravity onboard the NASA Lewis DC-9 aircraft, but did not show a radiative extinction boundary due to g-jitter (Variations in gravitational level and direction) effects. Dietrich conducted experiments in the reduced gravity environment of the Space Shuttle. This work showed that the extinction diameter of methanol droplets increased when the initial diameter of the droplets was large (in this case, approximately 5 mm). Theoretical results agreed with these experimental results only when the theory included radiative effects . Radiative extinction was experimentally verified by Nayagam in a later Shuttle mission. The following work focuses on the combustion and extinction of a single fuel droplet. The goal is to experimentally determine a large droplet diameter limit that

  3. Dispersion properties of transverse anisotropic liquid crystal core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Karasawa, Naoki

    2016-04-01

    The dispersion properties of liquid crystal core photonic crystal fibers for different core diameters have been calculated by a full vectorial finite difference method. In calculations, air holes are assumed to be arranged in a regular hexagonal array in fused silica and a central hole is filled with liquid crystal to create a core. In this study, three types of transverse anisotropic configurations, where liquid crystal molecules are oriented in a transverse plane, and a planar configuration, where liquid crystal molecules are oriented in a propagation direction, are considered. The large changes of the dispersion properties are found when the orientation of the liquid crystal molecules is changed from a planar configuration to a uniform configuration, where all molecules are oriented in the same direction in a transverse plane. Since the orientation of liquid crystal molecules may be controlled by applying an electric field, it could be utilized for various applications including the spectral control of supercontinuum generation.

  4. Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Wright, John D.

    1995-02-01

    This book describes the chemical and physical structure of molecular crystals, their optical and electronic properties, and the reactions between neighboring molecules in crystals. In the second edition, the author has taken into account research that has undergone extremely rapid development since the first edition was published in 1987. For instance, he gives extensive coverage to the applications of molecular materials in high-technology devices (e.g. optical communications, laser printers, photocopiers, liquid crystal displays, solar cells, and more). There is also an entirely new chapter on the recently discovered Buckminsterfullerene carbon molecule (C60) and organic non-linear optic materials.

  5. Gold nanoparticle capture within protein crystal scaffolds

    NASA Astrophysics Data System (ADS)

    Kowalski, Ann E.; Huber, Thaddaus R.; Ni, Thomas W.; Hartje, Luke F.; Appel, Karina L.; Yost, Jarad W.; Ackerson, Christopher J.; Snow, Christopher D.

    2016-06-01

    DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was confirmed by single crystal X-ray crystallography.DNA assemblies have been used to organize inorganic nanoparticles into 3D arrays, with emergent properties arising as a result of nanoparticle spacing and geometry. We report here the use of engineered protein crystals as an alternative approach to biologically mediated assembly of inorganic nanoparticles. The protein crystal's 13 nm diameter pores result in an 80% solvent content and display hexahistidine sequences on their interior. The hexahistidine sequence captures Au25(glutathione)~17 (nitrilotriacetic acid)~1 nanoclusters throughout a chemically crosslinked crystal via the coordination of Ni(ii) to both the cluster and the protein. Nanoparticle loading was validated by confocal microscopy and elemental analysis. The nanoparticles may be released from the crystal by exposure to EDTA, which chelates the Ni(ii) and breaks the specific protein/nanoparticle interaction. The integrity of the protein crystals after crosslinking and nanoparticle capture was

  6. Growth of shaped single crystals of proteins

    NASA Astrophysics Data System (ADS)

    Moreno, Abel; Rondón, Deyanira; García-Ruiz, Juan Ma.

    1996-09-01

    We present a procedure for obtaining protein single crystals that fill the capillary tubes in which they grow. The implementation was typical of the gel acupuncture method and the four different proteins are used as examples: lysozyme (HEW), thaumatin I, ferritin and insulin. Rod- and prismatic-shaped protein single crystals of these four proteins were grown inside capillary tubes of 0.2, 0.3, 0.5 mm in diameter and, for the case of lysozyme, up to 1.2 mm in diameter. The maximum length measured along the long axes of the rod crystals was 1.6 mm again for lysozyme crystals. It was observed that, once the capillary tube was filled, the crystal continues to grow by diffusion of the precipitating agent throughout the porous network formed by the protein crystal structure. We also discuss the possibility of growing these cylinders of crystalline proteins by the addition of protein solution to the mother liquor through the upper end of the glass capillary while the precipitating agent diffuses through the protein crystal itself. X-ray diffraction patterns confirm the single crystal character of the protein rods.

  7. 50 μm core diameter Yb³⁺Al³⁺/F⁻ codoped silica fiber with M²<1.1 beam quality.

    PubMed

    Xu, Wenbin; Lin, Zhiquan; Wang, Meng; Feng, Suya; Zhang, Lei; Zhou, Qinling; Chen, Danping; Zhang, Liyan; Wang, Shikai; Yu, Chunlei; Hu, Lili

    2016-02-01

    This paper reports, for the first time to our best knowledge, a nearly diffraction-limited output in a Yb(3+)/Al(3+)/F(-) codoped double cladding silica fiber with a 50 μm core diameter and 0.02 core NA. The core glass with a diameter >6  mm was fabricated through solgel process combined with high temperature sintering. Laser performances of this fiber at different bend diameters were studied. The mean M2<1.1 in this 50 μm core diameter fiber was achieved at a bend diameter of 0.35 m. The core glass with the refractive index nearly equal to pure silica glass is suitable for the fiber design, such as large-mode-area photonic crystal fiber. PMID:26907409

  8. Memory, emotion, and pupil diameter: Repetition of natural scenes.

    PubMed

    Bradley, Margaret M; Lang, Peter J

    2015-09-01

    Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes. PMID:25943211

  9. Parametric Probability Distribution Functions for Axon Diameters of Corpus Callosum

    PubMed Central

    Sepehrband, Farshid; Alexander, Daniel C.; Clark, Kristi A.; Kurniawan, Nyoman D.; Yang, Zhengyi; Reutens, David C.

    2016-01-01

    Axon diameter is an important neuroanatomical characteristic of the nervous system that alters in the course of neurological disorders such as multiple sclerosis. Axon diameters vary, even within a fiber bundle, and are not normally distributed. An accurate distribution function is therefore beneficial, either to describe axon diameters that are obtained from a direct measurement technique (e.g., microscopy), or to infer them indirectly (e.g., using diffusion-weighted MRI). The gamma distribution is a common choice for this purpose (particularly for the inferential approach) because it resembles the distribution profile of measured axon diameters which has been consistently shown to be non-negative and right-skewed. In this study we compared a wide range of parametric probability distribution functions against empirical data obtained from electron microscopy images. We observed that the gamma distribution fails to accurately describe the main characteristics of the axon diameter distribution, such as location and scale of the mode and the profile of distribution tails. We also found that the generalized extreme value distribution consistently fitted the measured distribution better than other distribution functions. This suggests that there may be distinct subpopulations of axons in the corpus callosum, each with their own distribution profiles. In addition, we observed that several other distributions outperformed the gamma distribution, yet had the same number of unknown parameters; these were the inverse Gaussian, log normal, log logistic and Birnbaum-Saunders distributions. PMID:27303273

  10. Diameter-dependent solubility of single-walled carbon nanotubes.

    PubMed

    Duque, Juan G; Parra-Vasquez, A Nicholas G; Behabtu, Natnael; Green, Micah J; Higginbotham, Amanda L; Price, B Katherine; Leonard, Ashley D; Schmidt, Howard K; Lounis, Brahim; Tour, James M; Doorn, Stephen K; Cognet, Laurent; Pasquali, Matteo

    2010-06-22

    We study the solubility and dispersibility of as-produced and purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions of the HiPco process are found to lead to significant differences in the respective SWNT solubilities in oleum and surfactant suspensions. The diameter distributions of SWNTs dispersed in surfactant solutions are batch-dependent, as evidenced by luminescence and Raman spectroscopies, but are identical for metallic and semiconducting SWNTs within a batch. We thus find that small diameter SWNTs disperse at higher concentration in aqueous surfactants and dissolve at higher concentration in oleum than do large-diameter SWNTs. These results highlight the importance of controlling SWNT synthesis methods in order to optimize processes dependent on solubility, including macroscopic processing such as fiber spinning, material reinforcement, and films production, as well as for fundamental research in type selective chemistry, optoelectronics, and nanophotonics. PMID:20521799

  11. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±∼20% and ±∼40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  12. NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos

    NASA Astrophysics Data System (ADS)

    Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; Masiero, J.; Sonnett, S.; Wright, E. L.

    2016-09-01

    The Near-Earth Object Wide-Field Infrared Survey Explorer (NEOWISE) mission continues to detect, track, and characterize minor planets. We present diameters and albedos calculated from observations taken during the second year since the spacecraft was reactivated in late 2013. These include 207 near-Earth asteroids (NEAs) and 8885 other asteroids. Of the NEAs, 84% NEAs did not have previously measured diameters and albedos by the NEOWISE mission. Comparison of sizes and albedos calculated from NEOWISE measurements with those measured by occultations, spacecraft, and radar-derived shapes shows accuracy consistent with previous NEOWISE publications. Diameters and albedos fall within ±˜20% and ±˜40%, 1-sigma, respectively, of those measured by these alternate techniques. NEOWISE continues to preferentially discover near-Earth objects which are large (>100 m), and have low albedos.

  13. Nanofiber alignment of a small diameter elastic electrospun scaffold

    NASA Astrophysics Data System (ADS)

    Patel, Jignesh

    Cardiovascular disease is the leading cause of death in western countries with coronary heart disease making up 50% of these deaths. As a treatment option, tissue engineered grafts have great potential. Elastic scaffolds that mimic arterial extracellular matrix (ECM) may hold the key to creating viable vascular grafts. Electrospinning is a widely used scaffold fabrication technique to engineer tubular scaffolds. In this study, we investigated how the collector rotation speed altered the nanofiber alignment which may improve mechanical characteristics making the scaffold more suitable for arterial grafts. The scaffold was fabricated from a blend of PCL/Elastin. 2D Fast Fourier Transform (FFT) image processing tool and MatLab were used to quantitatively analyze nanofiber orientation at different collector speeds (13500 to 15500 rpm). Both Image J and MatLab showed graphical peaks indicating predominant fiber orientation angles. A collector speed of 15000 rpm was found to produce the best nanofiber alignment with narrow peaks at 90 and 270 degrees, and a relative amplitude of 200. This indicates a narrow distribution of circumferentially aligned nanofibers. Collector speeds below and above 15000 rpm caused a decrease in fiber alignment with a broader orientation distribution. Uniformity of fiber diameter was also measured. Of 600 measures from the 15000 rpm scaffolds, the fiber diameter range from 500 nm to 899 nm was most prevalent. This diameter range was slightly larger than native ECM which ranges from 50 nm to 500 nm. The second most prevalent diameter range had an average of 404 nm which is within the diameter range of collagen. This study concluded that with proper electrospinning technique and collector speed, it is possible to fabricate highly aligned small diameter elastic scaffolds. Image J 2D FFT results confirmed MatLab findings for the analyses of circumferentially aligned nanofibers. In addition, MatLab analyses simplified the FFT orientation data

  14. Blood viscosity in tube flow: dependence on diameter and hematocrit.

    PubMed

    Pries, A R; Neuhaus, D; Gaehtgens, P

    1992-12-01

    Since the original publications by Martini et al. (Dtsch. Arch. Klin. Med. 169: 212-222, 1930) and Fahraeus and Lindqvist (Am. J. Physiol. 96: 562-568, 1931), it has been known that the relative apparent viscosity of blood in tube flow depends on tube diameter. Quantitative descriptions of this effect and of the dependence of blood viscosity on hematocrit in the different diameter tubes are required for the development of hydrodynamic models of blood flow through the microcirculation. The present study provides a comprehensive data base for the description of relative apparent blood viscosity as a function of tube diameter and hematocrit. Data available from the literature are compiled, and new experimental data obtained in a capillary viscometer are presented. The combined data base comprises measurements at high shear rates (u > or = 50 s-1) in tubes with diameters ranging from 3.3 to 1,978 microns at hematocrits of up to 0.9. If corrected for differences in suspending medium viscosity and temperature, the data show remarkable agreement. Empirical fitting equations predicting relative apparent blood viscosity from tube diameter and hematocrit are presented. A pronounced change in the hematocrit dependence of relative viscosity is observed in a range of tube diameters in which viscosity is minimal. While a linear hematocrit-viscosity relationship is found in tubes of < or = 6 microns, an overproportional increase of viscosity with hematocrit prevails in tubes of > or = 9 microns. This is interpreted to reflect the hematocrit-dependent transition from single- to multifile arrangement of cells in flow. PMID:1481902

  15. The heliometric Astrolabe, a new instrument for solar diameter observations

    NASA Astrophysics Data System (ADS)

    Andrei, A. H.; Reis Neto, E.; D'Ávila, V. A.; Penna, J. L.; Assafin, M.; Boscardin, S. C.; De Avila, K. N.

    2006-10-01

    The Observatorio Nacional takes part in the Reseau de Suivi au Sol du Rayon Solaire (the international solar diameter monitoring network) which co-participates in the PICARD micro satellite, to be launched in 2008 to study the Earth climate and Sun variability relationship. A new instrument, a heliometer, was devised in order to minimize the atmospheric turbulence and reach data accuracy compatible with PICARD's. The heliometer principle of double images will be added to the astrolabe metrological quality, and fully digitized acquisition. The objective is to obtain two simultaneous images from the Sun, with fixed angular separation of about 30', which variation will contain the signature of the diameter variation.

  16. High purity germanium crystal growth at the University of South Dakota

    NASA Astrophysics Data System (ADS)

    Wang, Guojian; Mei, Hao; Mei, Dongming; Guan, Yutong; Yang, Gang

    2015-05-01

    High-purity germanium crystal growth is challenging work, requiring the control of individual crystal properties such as the impurity distribution, the dislocation density, and the crystalline structure. Currently, we grow high-purity germanium crystals by the Czochralski method in our laboratory in order to understand the details of the growing process, especially for large diameter crystals. In this paper, we report the progress of detector-grade germanium crystal growth at the University of South Dakota.

  17. Production of a large-diameter uniform plasma by electron cyclotron resonance heating with a small-diameter Lisitano coil

    NASA Astrophysics Data System (ADS)

    Komori, A.; Takada, Y.; Yonesu, A.; Kawai, Y.

    1991-02-01

    A large-diameter uniform plasma is produced by electron cyclotron resonance heating with a slotted Lisitano coil of 9 cm in diameter by locating the resonance apart from the Lisitano coil. Although the plasma production with a Lisitano coil has been performed extensively by placing the resonance near the Lisitano coil, the influence of the resonance location has not received as much attention. When the resonance is located further than 8 cm from the Lisitano coil, the uniform plasma of ˜40 cm in diameter at densities of ˜1.2×1011 cm-3 is produced over the vacuum chamber with an inner radius of 46 cm. The microwave is propagated in the whole space between the resonance and the Lisitano coil, and spatial electric-field distributions of the microwave play an important role on forming the radially uniform plasma.

  18. Characterization of sodium chloride crystals grown in microgravity

    NASA Astrophysics Data System (ADS)

    Fontana, Pietro; Schefer, Jürg; Pettit, Donald

    2011-06-01

    NaCl crystals grown by the evaporation of an aqueous salt solution in microgravity on the International Space Station (ISS) were characterized and compared to salt crystals grown on earth. NaCl crystallized as thin wafers in a supersaturated film of 200-700 μm thickness and 50 mm diameter, or as hopper cubes in 10 mm diameter supersaturated spheres. Neutron diffraction shows no change in crystal structure and in cell parameters compared to earth-grown crystals. However, the morphology can be different, frequently showing circular, disk-like shapes of single crystals with <1 1 1> perpendicular to the disks, an unusual morphology for salt crystals. In contrast to the growth on earth the lateral faces of the microgravity tabular hopper crystals are symmetrical because they are free floating during the crystallization process. Hopper cubes were produced without the need to suspend the growing crystals by an ongoing stirring. "Fleur de Sel" is shown as an example of two-dimensional growth of salt on earth and compared to the space grown crystals. It is shown that in microgravity conditions brine fluid inclusions form within the salt crystals.

  19. Two-dimensional metal-glass photonic crystal

    NASA Astrophysics Data System (ADS)

    Pysz, Dariusz; Kujawa, Ireneusz; Stępień, Ryszard; Dominiak, Radosław; Pniewski, Jacek; Szoplik, Tomasz

    2007-04-01

    We present recent achievements in fabricating a two-dimensional (2D) photonic crystal in the form of a bundle of parallel micro- or nanowires embedded in glass matrix. The method is similar to that of sequential thinning used for fabrication of photonic crystal fibers. We discuss technological issues that aim at preservation of regularity of photonic crystal lattice and uniformity of wire diameters. Proper selection of a melting point of metal alloy and the range of temperatures of glass viscosity leads to reduction of regularity losses resulting from sequential processes of drawing. Measured distributions of crystal lattices, wire diameters and shapes of wires are used to simulate photonic band structure of fabricated crystals. This work is directed toward fabrication of a photonic crystal showing the negative refraction in the near infrared and visible spectral range.

  20. Real-time precision measuring device of tree diameter growth

    NASA Astrophysics Data System (ADS)

    Guo, Mingming; Chen, Aijun; Li, Dongsheng; Liu, Nan; Yao, Jingyuan

    2016-01-01

    DBH(diameter at breast height) is an important factor to reflect of the quality of plant growth, also an important parameter indispensable in forest resources inventory and forest carbon sink, the accurate measurement of DBH or not is directly related to the research of forest resources inventory and forest carbon sink. In this paper, the principle and the mathematical model of DBH measurement device were introduced, the fixture measuring device and the hardware circuit for this tree diameter were designed, the measurement software programs were compiled, and the precision measuring device of tree diameter growth was developed. Some experiments with Australia fir were conducted. Based on experiment data, the correlations among the DBH variation of Australian fir, the environment temperature, air humility and PAR(photosynthetically active radiation) were obtained. The effects of environmental parameters (environment temperature, air humility and PAR) on tree diameter were analyzed. Experimental results show that there is a positive correlation between DBH variation of Australian fir and environment temperature, a negative correlation between DBH variation of Australian fir and air humility , so is PAR.

  1. Solar diameter measurements for study of Sun climate coupling

    NASA Technical Reports Server (NTRS)

    Hill, H. A.

    1983-01-01

    Changes in solar shape and diameter were detected as a possible probe of variability in solar luminosity, an important climatic driving function. A technique was designed which will allow the calibration of the telescope field, providing a scale for long-term comparison of these and future measurements.

  2. Decrease rate of the renal diameter in chronic hemodialysis patients.

    PubMed

    Aoyagi, Teiichiro; Tachibana, Masaaki; Naganuma, Shinji

    2013-01-01

    We here present the results of ultrasonographic (US) evaluations on the alteration of renal diameter of chronic HD patients. Of 109 outpatient HD patients who had neither severe acquired cystic disease of the kidney nor hereditary polycystic kidney disease, we performed US two or three times to measure their maximum renal diameter (mean of both kidneys), and the yearly alteration rate was calculated. The average interval of the two measurements was 35.9 months, and the average HD duration from the HD induction to the first measurement was 29.5 months. The average decrease rate of renal diameter was 4.34 ± 0.4 (SE) mm/year. No statistical difference was seen on the decrease rate in relation to gender, age and original disease (among three groups, glomerulonephritis and IgA nephropathy, diabetes, and others including hypertension). However, the decrease rate was large when the first measurement was close to the induction of hemodialysis, suggesting that the alteration rate reduced according to the hemodialysis vintage (5.3 ± 0.8 mm/year, first measurement not more than 10 months after induction of HD and 1.5 ± 1.6 mm/year, first measurement more than 80 months after induction of HD). Renal diameter decreased approximately 4.3 mm each year, and the decrease rate slowed as the length of time on dialysis increased. PMID:24967236

  3. Rowlinson’s concept of an effective hard sphere diameter

    PubMed Central

    Henderson, Douglas

    2010-01-01

    Attention is drawn to John Rowlinson’s idea that the repulsive portion of the intermolecular interaction may be replaced by a temperature-dependent hard sphere diameter. It is this approximation that made the development of perturbation theory possible for realistic fluids whose intermolecular interactions have a steep, but finite, repulsion at short separations. PMID:20953320

  4. Measuring the Diameter of a Hair with a Steel Rule.

    ERIC Educational Resources Information Center

    Macdonald, John; O'Leary, Sean V.

    1994-01-01

    Describes a technique that uses a helium neon laser, a steel rule, a wooden rule, and a piece of paper to measure the diameter of a hair using the diffraction of light. Details on technique, mathematics, and sources of error are provided. (DDR)

  5. Ratio of Spleen Diameter to Red Blood Cell Distribution Width

    PubMed Central

    Balaban, Daniel Vasile; Popp, Alina; Lungu, Andrei Marian; Costache, Raluca Simona; Anca, Ioana Alina; Jinga, Mariana

    2015-01-01

    Abstract Celiac disease (CD) is currently considerably underdiagnosed, setting the need for developing tools to select patients with probability of CD, who warrant further testing. Red blood cell distribution width (RDW) has been shown in previous studies to be a sensitive predictor for CD, but it lacks specificity. Splenic hypotrophy is also noted frequently in celiac patients. Our aim was to evaluate if spleen diameter to RDW ratio can be used as an indicator for CD. We evaluated 15 newly diagnosed CD patients, 52 patients with inflammatory bowel disease, and 35 patients with irritable bowel syndrome (IBS). We evaluated the differences in spleen diameter, RDW, and their ratio among the four groups. Two-thirds of the CD patients had elevated RDW, compared to 9% in the IBS group. A small spleen was seen in 80% of the celiacs, compared to 21.9% in the ulcerative colitis group, 10% in the Crohn disease group, and 9% in the IBS group. A spleen diameter to RDW ratio under 6 had a sensitivity of 73.3% and specificity of 88.5% in predicting CD, with an AUROC of 0.737. Spleen diameter to RDW ratio is a simple, widely available score, which can be used to select adult patients with probability of CD. PMID:25881851

  6. Asteroid magnitudes, UBV colors, and IRAS albedos and diameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1989-01-01

    This paper lists absolute magnitudes and slope parameters for known asteroids numbered through 3318. The values presented are those used in reducing asteroid IR flux data obtained with the IRAS. U-B colors are given for 938 asteroids, and B-V colors are given for 945 asteroids. The IRAS albedos and diameters are tabulated for 1790 asteroids.

  7. Combined position and diameter measures for lunar craters

    USGS Publications Warehouse

    Arthur, D.W.G.

    1977-01-01

    The note addresses the problem of simultaneously measuring positions and diameters of circular impact craters on wide-angle photographs of approximately spherical planets such as the Moon and Mercury. The method allows for situations in which the camera is not aligned on the planet's center. ?? 1977.

  8. Assessment of vessel diameters for MR brain angiography processed images

    NASA Astrophysics Data System (ADS)

    Moraru, Luminita; Obreja, Cristian-Dragos; Moldovanu, Simona

    2015-12-01

    The motivation was to develop an assessment method to measure (in)visible differences between the original and the processed images in MR brain angiography as a method of evaluation of the status of the vessel segments (i.e. the existence of the occlusion or intracerebral vessels damaged as aneurysms). Generally, the image quality is limited, so we improve the performance of the evaluation through digital image processing. The goal is to determine the best processing method that allows an accurate assessment of patients with cerebrovascular diseases. A total of 10 MR brain angiography images were processed by the following techniques: histogram equalization, Wiener filter, linear contrast adjustment, contrastlimited adaptive histogram equalization, bias correction and Marr-Hildreth filter. Each original image and their processed images were analyzed into the stacking procedure so that the same vessel and its corresponding diameter have been measured. Original and processed images were evaluated by measuring the vessel diameter (in pixels) on an established direction and for the precise anatomic location. The vessel diameter is calculated using the plugin ImageJ. Mean diameter measurements differ significantly across the same segment and for different processing techniques. The best results are provided by the Wiener filter and linear contrast adjustment methods and the worst by Marr-Hildreth filter.

  9. Estimating Tree Height-Diameter Models with the Bayesian Method

    PubMed Central

    Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the “best” model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  10. General view of outside diameter welding stations of the saw ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    General view of outside diameter welding stations of the saw line in bay 8 of the main pipe mill building looking northwest. - U.S. Steel National Tube Works, Main Pipe Mill Building, Along Monongahela River, McKeesport, Allegheny County, PA

  11. 5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. 30 DIAMETER ACCESS MANHOLE IN THE CENTER OF THE GATE HOUSE, LOOKING SOUTH. - Washington Water Power Spokane River Upper Falls Hydroelectric Development, Gates & Gate-Lifting Mechanisms, Spokane River, approximately 0.5 mile northeast of intersection of Spokane Falls Boulevard & Post Street, Spokane, Spokane County, WA

  12. Non-Contact EDDY Current Hole Eccentricity and Diameter Measurement

    NASA Technical Reports Server (NTRS)

    Chern, E. James

    1998-01-01

    Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact eddy current hole diameter and eccentricity measuring system. The operating principle is based on the eddy current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute eddy current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An eddy current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact eddy current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.

  13. View of wood stave penstocks (four feet in diameter) with ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    View of wood stave penstocks (four feet in diameter) with steel bands, wood and steel frames; standing on top of penstocks is Doug Hamilton (right), Nooksack Falls hydro-plant operator for puget power, and Ken Rose (left) HAER Historian. - Nooksack Falls Hydroelectric Plant, Route 542, Glacier, Whatcom County, WA

  14. Minimum tube diameters for steady propagation of gaseous detonations

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Ng, H. D.; Lee, J. H. S.

    2014-07-01

    Recent experimental results on detonation limits are reported in this paper. A parametric study was carried out to determine the minimum tube diameters for steady detonation propagation in five different hydrocarbon fuel-oxygen combustible mixtures and in five polycarbonate test tube diameters ranging from 50.8 mm down to a small scale of 1.5 mm. The wave propagation in the tube was monitored by optical fibers. By decreasing the initial pressure, hence the sensitivity of the mixture, the onset of limits is indicated by an abrupt drop in the steady detonation velocity after a short distance of travel. From the measured wave velocities inside the test tube, the critical pressure corresponding to the limit and the minimum tube diameters for the propagation of the detonation can be obtained. The present experimental results are in good agreement with previous studies and show that the measured minimum tube diameters can be reasonably estimated on the basis of the /3 rule over a wide range of conditions, where is the detonation cell size. These new data shall be useful for safety assessment in process industries and in developing and validating models for detonation limits.

  15. Downhole pumps for water sampling in small diameter wells

    USGS Publications Warehouse

    Koopman, F. C.

    1979-01-01

    The relatively high cost and difficulty in locating a source of pumps for use in obtaining ground-water samples from small-diameter wells has demonstrated a need for this report. Criteria for selection of a pump and pumping equipment to meet specific requirements has been tabulated to assist field personnel in making a selection from commercial sources. (Kosco-USGS)

  16. Estimating tree height-diameter models with the Bayesian method.

    PubMed

    Zhang, Xiongqing; Duan, Aiguo; Zhang, Jianguo; Xiang, Congwei

    2014-01-01

    Six candidate height-diameter models were used to analyze the height-diameter relationships. The common methods for estimating the height-diameter models have taken the classical (frequentist) approach based on the frequency interpretation of probability, for example, the nonlinear least squares method (NLS) and the maximum likelihood method (ML). The Bayesian method has an exclusive advantage compared with classical method that the parameters to be estimated are regarded as random variables. In this study, the classical and Bayesian methods were used to estimate six height-diameter models, respectively. Both the classical method and Bayesian method showed that the Weibull model was the "best" model using data1. In addition, based on the Weibull model, data2 was used for comparing Bayesian method with informative priors with uninformative priors and classical method. The results showed that the improvement in prediction accuracy with Bayesian method led to narrower confidence bands of predicted value in comparison to that for the classical method, and the credible bands of parameters with informative priors were also narrower than uninformative priors and classical method. The estimated posterior distributions for parameters can be set as new priors in estimating the parameters using data2. PMID:24711733

  17. Continuous measurement of vascular diameters via television microscopy.

    PubMed

    Devaney, M J; Rathke, J E; Bartel, R W; Mcdonald, J E; Wiegman, D L; Miller, F N; Harris, P D

    1976-01-01

    In the past 10 years, microcirculation studies have emphasized quantitative measurements of microvascular diameters to characterize in vivo small vessel responses to experimental forcings such as hemorrhage, anesthesia, and hypoxia. We have developed an instrument to obtain continuous diameter measurements of a small artery and vein (40-200 mu) via closed-circuit television microscopy. The outputs are analog voltages proportional to the vessel diameters. Video processing is limited to two image areas termed "windows," which are defined by markers on the monitor and positioned over separate vertically aligned vessels. Each vessel, which appears darker than the surrounding tissue, is located by comparing the video signal to a reference voltage that adapts to changes in the relative contrast within the window. In the presence of a vessel, a ramp voltage is generated, the peak value of which is proportional to the vessel diameter. These peaks are averaged over the 15-video lines of the window and over several video frames to reduce noise sensitivity. In order to accommodate preparation movement such as skeletal muscle contraction, window position and width automatically adapt to changes in vessel position and width. Visual verification of system performance is provided by clamping the video signal to white on that portion of the image which the instrument identifies as vessel. PMID:950283

  18. Genetic and Environmental Effects on the Abdominal Aortic Diameter Development

    PubMed Central

    Tarnoki, Adam Domonkos; Tarnoki, David Laszlo; Littvay, Levente; Garami, Zsolt; Karlinger, Kinga; Berczi, Viktor

    2016-01-01

    Background Configuration of the abdominal aorta is related to healthy aging and a variety of disorders. Objectives We aimed to assess heritable and environmental effects on the abdominal aortic diameter. Methods 114 adult (69 monozygotic, 45 same-sex dizygotic) twin pairs (mean age 43.6 ± 16.3 years) underwent abdominal ultrasound with Esaote MyLab 70X ultrasound machine to visualize the abdominal aorta below the level of the origin of the renal arteries and 1-3 cm above the bifurcation. Results Age- and sex-adjusted heritability of the abdominal aortic diameter below the level of the origin of the renal arteries was 40% [95% confidence interval (CI), 14 to 67%] and 55% above the aortic bifurcation (95% CI, 45 to 70%). None of the aortic diameters showed common environmental effects, but unshared environmental effects were responsible for 60% and 45% of the traits, respectively. Conclusions Our analysis documents the moderate heritability and its segment-specific difference of the abdominal aortic diameter. The moderate part of variance was explained by unshared environmental components, emphasizing the importance of lifestyle factors in primary prevention. Further studies in this field may guide future gene-mapping efforts and investigate specific lifestyle factors to prevent abdominal aortic dilatation and its complications. PMID:26559855

  19. Macroscopic Crystallization of Nanocrystals into Supercrystals

    NASA Astrophysics Data System (ADS)

    Nakajima, Toshio; Nagasawa, Hiroshi; Maruyama, Minoru; Komatsu, Teruo; Isoda, Seiji; Nelson, Jon

    2004-03-01

    We report here the crystallization of spherical, 4.7-nm-diameter Ag nanocrystals, passivated with a fatty-acid surface coating, into well-facetted supercrystals up to 500-μm across and about 1-μm thick.

  20. Liquid Crystals

    NASA Astrophysics Data System (ADS)

    1990-01-01

    Thermochromic liquid crystals, or TLCs, are a type of liquid crystals that react to changes in temperature by changing color. The Hallcrest/NASA collaboration involved development of a new way to visualize boundary layer transition in flight and in wind tunnel testing of aircraft wing and body surfaces. TLCs offered a new and potentially better method of visualizing the boundary layer transition in flight. Hallcrest provided a liquid crystal formulation technique that afforded great control over the sensitivity of the liquid crystals to varying conditions. Method is of great use to industry, government and universities for aerodynamic and hydrodynamic testing. Company's principal line is temperature indicating devices for industrial use, such as non-destructive testing and flaw detection in electric/electronic systems, medical application, such as diagnostic systems, for retail sale, such as room, refrigerator, baby bath and aquarium thermometers, and for advertising and promotion specials. Additionally, Hallcrest manufactures TLC mixtures for cosmetic applications, and liquid crystal battery tester for Duracell batteries.

  1. Nuclear criticality safety calculational analysis for small-diameter containers

    SciTech Connect

    LeTellier, M.S.; Smallwood, D.J.; Henkel, J.A.

    1995-11-01

    This report documents calculations performed to establish a technical basis for the nuclear criticality safety of favorable geometry containers, sometimes referred to as 5-inch containers, in use at the Portsmouth Gaseous Diffusion Plant. A list of containers currently used in the plant is shown in Table 1.0-1. These containers are currently used throughout the plant with no mass limits. The use of containers with geometries or material types other than those addressed in this evaluation must be bounded by this analysis or have an additional analysis performed. The following five basic container geometries were modeled and bound all container geometries in Table 1.0-1: (1) 4.32-inch-diameter by 50-inch-high polyethylene bottle; (2) 5.0-inch-diameter by 24-inch-high polyethylene bottle; (3) 5.25-inch-diameter by 24-inch-high steel can ({open_quotes}F-can{close_quotes}); (4) 5.25-inch-diameter by 15-inch-high steel can ({open_quotes}Z-can{close_quotes}); and (5) 5.0-inch-diameter by 9-inch-high polybottle ({open_quotes}CO-4{close_quotes}). Each container type is evaluated using five basic reflection and interaction models that include single containers and multiple containers in normal and in credible abnormal conditions. The uranium materials evaluated are UO{sub 2}F{sub 2}+H{sub 2}O and UF{sub 4}+oil materials at 100% and 10% enrichments and U{sub 3}O{sub 8}, and H{sub 2}O at 100% enrichment. The design basis safe criticality limit for the Portsmouth facility is k{sub eff} + 2{sigma} < 0.95. The KENO study results may be used as the basis for evaluating general use of these containers in the plant.

  2. Changes in retinal microvascular diameter in patients with diabetes

    PubMed Central

    da Silva, Andréa Vasconcellos Batista; Gouvea, Sonia Alves; da Silva, Aurélio Paulo Batista; Bortolon, Saulo; Rodrigues, Anabel Nunes; Abreu, Glaucia Rodrigues; Herkenhoff, Fernando Luiz

    2015-01-01

    Background and objectives Diabetic retinopathy is the main microvascular complication in diabetes mellitus and needs to be diagnosed early to prevent severe sight-threatening retinopathy. The purpose of this study was to quantify the retinal microvasculature pattern and analyze the influence of blood glucose level and the duration of diabetes mellitus on the retinal microvasculature. Methods Two groups were analyzed: patients with diabetes (N=26) and patients without diabetes, ie, controls (N=26). A quantitative semiautomated method analyzed retinal microvasculature. The diameters of arterioles and venules were measured. The total numbers of arterioles and venules were counted. The ratio of arteriole diameter to venule diameter was calculated. The retinal microvasculature pattern was related to clinical and biochemical parameters. Results Patients with diabetes exhibited larger venule diameters in the upper temporal quadrant of the retina compared to the lower temporal quadrant (124.85±38.03 µm vs 102.92±15.69 µm; P<0.01). Patients with diabetes for 5 or more years had larger venule diameters in the upper temporal quadrant than patients without diabetes (141.62±44.44 vs 112.58±32.11 µm; P<0.05). The degree of venodilation in the upper temporal quadrant was positively correlated with blood glucose level and the estimated duration of diabetes mellitus. Interpretation and conclusion The employed quantitative method demonstrated that patients with diabetes exhibited venule dilation in the upper temporal quadrant, and the duration of diabetes mellitus was positively correlated with blood glucose level. Therefore, the early assessment of retinal microvascular changes is possible prior to the onset of diabetic retinopathy. PMID:26345217

  3. Synthesis and bioconjugation of 2 and 3 nm-diameter gold nanoparticles.

    PubMed

    Ackerson, Christopher J; Jadzinsky, Pablo D; Sexton, Jonathan Z; Bushnell, David A; Kornberg, Roger D

    2010-02-17

    By adjustment of solvent conditions for synthesis, virtually monodisperse 4-mercaptobenzoic acid (p-MBA) monolayer-protected gold nanoparticles, 2 and 3 nm in diameter, were obtained. Large single crystals of the 2 nm particles could be grown from the reaction mixture. Uniformity was also demonstrated by the formation of two-dimensional arrays and by quantitative high-angle annular dark-field scanning transmission electron microscopy. The 2 and 3 nm particles were spontaneously reactive for conjugation with proteins and DNA, and further reaction could be prevented by repassivation with glutathione. Conjugates with antibody Fc fragment could be used to identify TAP-tagged proteins of interest in electron micrographs, through the binding of a pair of particles to the pair of protein A domains in the TAP tag. PMID:20099843

  4. Development of Methods of Producing Large Areas of Silicon Sheet by the Slicing of Silicon Ingots Using Inside Diameter (I.D.) Saws

    NASA Technical Reports Server (NTRS)

    Aharonyan, P.

    1979-01-01

    Methods of producing large areas of silicon sheets were developed by using inside diameter (I.D.) saws to slice silicon ingots. A 16 inch automated I.D. slicing machine was modified to accept programmable electric feed system, a crystal rotating system and a dyna-track blade monitoring and control system. The saw and accessories were used to slice 75 mm diameter single crystal silicon ingots while rotating them. The automated saw automatically recovered the wafers and loaded them into a cassette. The amount of material lost during slicing was reduced by using smaller blades than ones normally used to slice the wafers. Slicing runs on 100 mm diameter silicon is the next goal.

  5. How different is water crystallization from polymer crystallization under confinement?

    NASA Astrophysics Data System (ADS)

    Floudas, George; Suzuki, Yasuhito; Duran, Hatice; Steinhart, Martin; Butt, Hans-Juergen

    2015-03-01

    The freezing mechanism of water under confinement can be fundamentally different from the bulk. Despite fundamental importance, the lack of well-defined confining media precluded a systematic investigation. Herein we employ self-ordered nanoporous aluminum oxide (AAO) which contains arrays of discrete, parallel and cylindrical nanopores with uniform pore length and diameter to study the effect of confinement on water crystallization. By varying different parameters such as pore size, temperature and cooling rate, the respective conditions under which the hexagonal form (Ih) and the less common form of cubic ice (Ic) could be studied. We found a transition from heterogeneous nucleation of Ih to homogeneous nucleation of predominantly Ic with decreasing pore diameter. Furthermore, the monotropic Ic --> Ih transition commonly observed upon heating is suppressed inside pores having diameters <= 35 nm. These findings lead to the phase diagram of water under confinement. It contains a predominant cubic form, a form known to exist only in the upper atmosphere.There are many similarities between the freezing of water and the crystallization of polymers under confinement.

  6. Production and basic morphology of struvite crystals from a pilot-scale crystallization process.

    PubMed

    Huang, H; Mavinic, D S; Lo, K V; Koch, F A

    2006-03-01

    A pilot-scale, struvite crystallization process was operated using anaerobic digester supernatants from two, full-scale, treatment plants as influent. It was found that the produced struvite crystals were easily separated from the process and were composed of very pure struvite (91.2 % to 94.1 % purity), with small amounts of calcium and carbonate, and traces of iron and aluminum. Most of the harvested struvite crystals, which were an aggregation of numerous fine crystals, were round, hard and larger than 1.5 mm in mean diameter. The crystal retention time in the reactor and the magnesium dosage in the supernatant appeared to have a significant effect on the crystal size, hardness and morphology. PMID:16548204

  7. Electrically-tunable optical zoom system by using liquid crystal lenses

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Chen, Ming-Syuan; Lin, Hung-Chun

    2012-03-01

    An electrically-tunable optical zoom system using liquid crystal (LC) lenses is demonstrated. The mechanism of the optical zoom system is to use two lenses and a camera system to achieve focusing and zooming function. In this paper, we analyzed the imaging conditions and the magnification of the optical zoom system. The relation between the focusing properties of LC lenses and zoom ratio of the optical zoom system is also discussed. The electrically-tunable optical zoom system using two LC lenses has high zoom ratio (~7.9:1 to ~5.5:1), short system length (<10 cm) and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescopes and pico projectors.

  8. Performance of three pencil-type ionization chambers (10 cm) in computed tomography standard beams

    NASA Astrophysics Data System (ADS)

    de Castro, Maysa C.; Xavier, Marcos; Caldas, Linda V. E.

    2016-07-01

    The use of computed tomography (CT) has increased over the years, thus generating a concern about the doses received by patients undergoing this procedure. Therefore, it is necessary to perform routinely beam dosimetry with the use of a pencil-type ionization chamber. This detector is the most utilized in the procedures of quality control tests on this kind of equipment. The objective of this work was to perform some characterization tests in standard CT beams, as the saturation curve, polarity effect, ion collection efficiency and linearity of response, using three ionization chambers, one commercial and two developed at the IPEN.

  9. Physical vapor transport crystal growth of ZnO

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Jianping, Ma; Fuli, Liu; Yuan, Zang; Yantao, Liu

    2014-03-01

    Zinc oxide (ZnO) has a wide band gap, high stability and a high thermal operating range that makes it a suitable material as a semiconductor for fabricating light emitting diodes (LEDs) and laser diodes, photodiodes, power diodes and other semiconductor devices. Recently, a new crystal growth for producing ZnO crystal boules was developed, which was physical vapor transport (PVT), at temperatures exceeding 1500 °C under a certain system pressure. ZnO crystal wafers in sizes up to 50 mm in diameter were produced. The conditions of ZnO crystal growth, growth rate and the quality of ZnO crystal were analyzed. Results from crystal growth and material characterization are presented and discussed. Our research results suggest that the novel crystal growth technique is a viable production technique for producing ZnO crystals and substrates for semiconductor device applications.

  10. Shape Evolution of Detached Bridgman Crystals Grown in Microgravity

    NASA Technical Reports Server (NTRS)

    Volz, M. P.; Mazuruk, K.

    2015-01-01

    Detached (or dewetted) Bridgman crystal growth defines that process in which a gap exists between a growing crystal and the crucible wall. In microgravity, the parameters that influence the existence of a stable gap are the growth angle of the solidifying crystal, the contact angle between the melt and the crucible wall, and the pressure difference across the meniscus. During actual crystal growth, the initial crystal radius will not have the precise value required for stable detached growth. Beginning with a crystal diameter that differs from stable conditions, numerical calculations are used to analyze the transient crystal growth process. Depending on the initial conditions and growth parameters, the crystal shape will either evolve towards attachment at the crucible wall, towards a stable gap width, or inwards towards eventual collapse of the meniscus. Dynamic growth stability is observed only when the sum of the growth and contact angles exceeds 180 degrees.

  11. Shaped crystal growth of langasite-type piezoelectric single crystals and their physical properties.

    PubMed

    Yokota, Yuui; Yoshikawa, Akira; Futami, Yoshisuke; Sato, Masato; Tota, Kazushige; Onodera, Ko; Yanagida, Takayuki

    2012-09-01

    We have grown shape-controlled langasite-type crystals by the micro-pulling-down (μ-PD) method. Columnar shaped La(3)Ta(0.5)Ga(5.5)O(14) (LTG), Ca(3)NbGa(3)Si(2)O(14) (CNGS), Ca(3)TaGa(3)Si(2)O(14) (CTGS), Sr(3)NbGa(3)Si(2)O(14) (SNGS), and Sr(3)Ta- Ga(3)Si(2)O(14) (STGS) crystals were grown using a Pt-Rh crucible with a 3-mm-diameter columnar die at the bottom. All grown crystals showed high transparency except for the peripheral area and diameter of approximately 3 mm. The chemical phases at the central parts of the grown crystals were identified as a single phase of langasite-type structure and their lattice parameters were almost the same as those of crystals grown by the Czochralski (Cz) method; however, some impurity phases were observed in the peripheral area. In X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by the Cz method. The piezoelectric constant d(11) of the CNGS crystal was 3.98 pC/N; this value is well correlated with those of previous reports. PMID:23007752

  12. Unidirectional growth of <1 1 0> ammonium dihydrogen orthophosphate single crystal by Sankaranarayanan Ramasamy method

    NASA Astrophysics Data System (ADS)

    Sethuraman, K.; Ramesh Babu, R.; Gopalakrishnan, R.; Ramasamy, P.

    2006-09-01

    Unidirectional <1 1 0> ammonium dihydrogen orthophosphate single crystal was grown by Sankaranarayanan-Ramasamy (SR) method. <1 1 0>orientational seed was mounted at the bottom of the glass crucible and the crystal of diameter 20 mm and length 60 mm was successfully grown by this novel SR method. Almost 100% solute-crystal conversion efficiency was achieved.

  13. Growth of Cadmium-Zinc Telluride Crystals by Controlled Seeding Contactless Physical Vapor Transport

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Grasza, K.; Gillies, D.; Jerman, G.

    1996-01-01

    Bulk crystals of cadmium-zinc telluride, 23 mm in diameter and up to 45 grams in weight were grown. Controlled seed formation procedure was used to limit the number of grains in the crystal. Most uniform distribution of ZnTe in the crystals was obtained using excess (Cd + Zn) pressure in the ampoule.

  14. Synchrotron/crystal sample preparation

    NASA Astrophysics Data System (ADS)

    Johnson, R. Barry

    1993-07-01

    The Center for Applied Optics (CAO) of the University of Alabama in Huntsville (UAH) prepared this final report entitled 'Synchrotron/Crystal Sample Preparation' in completion of contract NAS8-38609, Delivery Order No. 53. Hughes Danbury Optical Systems (HDOS) is manufacturing the Advanced X-ray Astrophysics Facility (AXAF) mirrors. These thin-walled, grazing incidence, Wolter Type-1 mirrors, varying in diameter from 1.2 to 0.68 meters, must be ground and polished using state-of-the-art techniques in order to prevent undue stress due to damage or the presence of crystals and inclusions. The effect of crystals on the polishing and grinding process must also be understood. This involves coating special samples of Zerodur and measuring the reflectivity of the coatings in a synchrotron system. In order to gain the understanding needed on the effect of the Zerodur crystals by the grinding and polishing process, UAH prepared glass samples by cutting, grinding, etching, and polishing as required to meet specifications for witness bars for synchrotron measurements and for investigations of crystals embedded in Zerodur. UAH then characterized these samples for subsurface damage and surface roughness and figure.

  15. Synchrotron/crystal sample preparation

    NASA Technical Reports Server (NTRS)

    Johnson, R. Barry

    1993-01-01

    The Center for Applied Optics (CAO) of the University of Alabama in Huntsville (UAH) prepared this final report entitled 'Synchrotron/Crystal Sample Preparation' in completion of contract NAS8-38609, Delivery Order No. 53. Hughes Danbury Optical Systems (HDOS) is manufacturing the Advanced X-ray Astrophysics Facility (AXAF) mirrors. These thin-walled, grazing incidence, Wolter Type-1 mirrors, varying in diameter from 1.2 to 0.68 meters, must be ground and polished using state-of-the-art techniques in order to prevent undue stress due to damage or the presence of crystals and inclusions. The effect of crystals on the polishing and grinding process must also be understood. This involves coating special samples of Zerodur and measuring the reflectivity of the coatings in a synchrotron system. In order to gain the understanding needed on the effect of the Zerodur crystals by the grinding and polishing process, UAH prepared glass samples by cutting, grinding, etching, and polishing as required to meet specifications for witness bars for synchrotron measurements and for investigations of crystals embedded in Zerodur. UAH then characterized these samples for subsurface damage and surface roughness and figure.

  16. Helical magneto-cumulative generator 280 mm in diameter

    NASA Astrophysics Data System (ADS)

    Demidov, V. A.; Kazakov, S. A.; Boriskin, A. S.; Vlasov, Yu. V.; Yanenko, V. A.; Nikolaev, N. I.; Volodchenkov, S. I.

    2015-01-01

    Several possibilities of preamplifier energy and power increasing are considered: using a more powerful (HMX-based) conical HE-charge in the central tube of the magneto-cumulative generator, using a magnetic flux finish pressing out device with axial initiation of the HE charge, and increasing the inner diameter of the helix. A magneto-cumulative generator (MCG) with a helix 280 mm in diameter (MCG-280) is developed. The new preamplifier has a power of ≈400 GW and is able to power a ten-element DMCG480 with an initial inductance of ≈0.2 µH by a current of ≈10 MA with a characteristic current rise time (by a factor of e at the final stage of its operation) τ e = 32 µs.

  17. Angular diameter distances reconsidered in the Newman and Penrose formalism

    NASA Astrophysics Data System (ADS)

    Kling, Thomas P.; Aly, Aly

    2016-02-01

    Using the Newman and Penrose spin coefficient (NP) formalism, we provide a derivation of the Dyer-Roeder equation for the angular diameter distance in cosmological space-times. We show that the geodesic deviation equation written in NP formalism is precisely the Dyer-Roeder equation for a general Friedman-Robertson-Walker (FRW) space-time, and then we examine the angular diameter distance to redshift relation in the case that a flat FRW metric is perturbed by a gravitational potential. We examine the perturbation in the case that the gravitational potential exhibits the properties of a thin gravitational lens, demonstrating how the weak lensing shear and convergence act as source terms for the perturbed Dyer-Roeder equation.

  18. Steering knuckle diameter measurement based on optical 3D scanning

    NASA Astrophysics Data System (ADS)

    Song, Li-mei; Li, Da-peng; Chang, Yu-lan; Xi, Jiang-tao; Guo, Qing-hua

    2014-11-01

    To achieve accurate measurements, the creating a fitting hole for internal diameter (CFHID) measurement method and the establishing multi-sectional curve for external diameter (EMCED) measurement method are proposed in this paper, which are based on computer vision principle and three-dimensional (3D) reconstruction. The methods are able to highlight the 3D characteristics of the scanned object and to achieve the accurate measurement of 3D data. It can create favorable conditions for realizing the reverse design and 3D reconstruction of scanned object. These methods can also be applied to dangerous work environment or the occasion that traditional contact measurement can not meet the demands, and they can improve the security in measurement.

  19. Predicting The Tube Diameter For Polymer Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2005-03-01

    A simple conjecture, relating the tube diameter to a characteristic length called the packing length, works well for all flexible entangled polymer melts. This is a remarkable result, because the tube diameter represents the confining effect of uncrossability of the chains, whereas the packing length is determined only by a chain's bulkiness and flexibility. I extend this conjecture to solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of blobs per entanglement strand is not a constant as had been previously assumed, but depends on the ratio of the packing length to the thermal blob size. Finally, I suggest that the packing length can be related to the Gauss winding number density, thus providing a topological basis for the conjecture.

  20. Large Diameter Shuttle Launched-AEM (LDSL-AEM) study

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A technical description of a Large Diameter Shuttle Launched-AEM (LDSL-AEM), an AEM base module adapted to carry 5 ft diameter payloads in the shuttle with propulsion for carrying payloads to higher altitude orbits from a 150 NM shuttle orbit, is described. The AEM is designed for launch on the scout launch vehicle. Onboard equipment provides capability to despin, acquire the earth, and control the vehicle in an earth pointing mode using reaction wheels for torque with magnets for all attitude acquisition, wheel desaturation, and nutation damping. Earth sensors in the wheels provide pitch and roll attitude. This system provides autonomous control capability to 1 degree in pitch and roll and 2 degrees in yaw. The attitude can be determined to .5 degrees in pitch and roll and 2 degrees in yaw.

  1. EFFECT OF PARTICLE DIAMETER ON EXCLUSION-ZONE SIZE

    PubMed Central

    NHAN, D.T.; POLLACK, G.H.

    2011-01-01

    Particles and solutes are excluded from the vicinity of hydrophilic surfaces, leaving large microsphere-free regions known as exclusion zones (EZs). Prior work had indicated that EZs could extend to distances of up to several hundred micrometers from the nucleating surface. These observations were made on large, extended surfaces, leaving open the question whether EZ size might depend on the characteristic dimension of the excluding surface. We placed one or few ion-exchange-resin beads whose diameters varied from 15 μm to 300 μm in cuvettes. The beads were suffused with aqueous microsphere suspensions for observing the surfaces’ exclusionary behavior. Results showed a direct relation between bead size and EZ size over the full range of bead diameter, implying a similar relation for smaller particles or molecules, perhaps extending beyond the resolution of the light microscope. PMID:22389653

  2. Comparing Crystals

    ERIC Educational Resources Information Center

    Sharp, Janet; Hoiberg, Karen; Chumbley, Scott

    2003-01-01

    This standard lesson on identifying salt and sugar crystals expands into an opportunity for students to develop their observation, questioning, and modeling skills. Although sugar and salt may look similar, students discovered that they looked very different under a magnifying glass and behaved differently when dissolved in water. In addition,…

  3. Therapeutic Crystals

    ERIC Educational Resources Information Center

    Bond, Charles S.

    2014-01-01

    Some readers might not fully know what the difference is between crystallography, and the "new age" practice of dangling crystals around the body to capitalise on their healing energy. The latter is often considered to be superstition, while ironically, the former has actually resulted in real rationally-based healing of human diseases…

  4. The diameter and thermal inertia of 433 Eros

    NASA Technical Reports Server (NTRS)

    Morrison, D.

    1976-01-01

    Radiometry of Eros at 10 and 20 micrometers demonstrates that the thermal conductivity of the upper centimeter of the surface is approximately as low as that of the moon, suggesting that the asteroid has a regolith of highly porous rocky material. When combined with photoelectric photometry, these infrared measurements yield an effective diameter of Eros at maximum light of 22 plus or minus 2 km and a geometric albedo of 0.18 plus or minus 0.03.

  5. Cohesive/cohesionless sediment transition diameter from settling velocity data

    NASA Astrophysics Data System (ADS)

    Mehta, Ashish J.; Letter, Joseph V.

    2015-09-01

    Mathematical models designed to simulate the movement of cohesive and cohesionless particles require as input the diameter d T specifying the transition between these two transport modes. As an effort to identify this diameter, Migniot (La Houille Blanche, 7, 591-620, 1968) measured in a water-filled column the settling velocities of flocs and respective deflocculated particles of mainly mineral cohesive sediments. The data were plotted as the ratio of the floc settling velocity to the particle velocity, called the flocculation factor F f , against particle diameter d s . The trend line was found to approximately follow an empirical power-law such that F f increased rapidly as d s decreased below d T estimated to be about 30 μm at F f = 1. Assuming fractal self-similarity among falling flocs, the power-law exponent of 5/3 is shown to correspond to a fractal dimension of 2.65 implying that the flocs were densely packed. The diameter d T depends on the electrochemical properties of the suspended particles as well as the kinetics of floc growth and breakup, hence to an extent on the method of determination of d T . Its value deduced more directly from measurement of the critical shear stress for erosion of flocs at the surface of cohesive sediment beds has been reported to be about 10 μm, which is lower than 30 μm. Among other reasons, it is likely that the difference is rooted in the limited experimental information available as well as difficulty in characterizing the effect of highly graded distributions of the particle settling velocity.

  6. NEOWISE Diameters and Albedos V1.0

    NASA Astrophysics Data System (ADS)

    Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; Nugent, C. R.; Sonnett, S. M.; Stevenson, R. A.; Wright, E. L.

    2016-06-01

    This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by NEOWISE during the fully cryogenic, 3-band cryo, post-cryo and NEOWISE-Reactivation Year 1 operations. It contains data covering near-Earth asteroids, Main Belt asteroids, active Main Belt objects, Hildas, Jupiter Trojans, Centaurs, and Jovian and Saturnian irregular satellites. Methodology for physical property determination is described in the referenced articles.

  7. Left Ventricular Diameter and Risk Stratification for Sudden Cardiac Death

    PubMed Central

    Narayanan, Kumar; Reinier, Kyndaron; Teodorescu, Carmen; Uy‐Evanado, Audrey; Aleong, Ryan; Chugh, Harpriya; Nichols, Gregory A.; Gunson, Karen; London, Barry; Jui, Jonathan; Chugh, Sumeet S.

    2014-01-01

    Background Left ventricular (LV) diameter is routinely measured on the echocardiogram but has not been jointly evaluated with the ejection fraction (EF) for risk stratification of sudden cardiac death (SCD). Methods and Results From a large ongoing community‐based study of SCD (The Oregon Sudden Unexpected Death Study; population ≈1 million), SCD cases were compared with geographic controls. LVEF and LV diameter, measured using the LV internal dimension in diastole (categorized as normal, mild, moderate, or severe dilatation using American Society of Echocardiography definitions) were assessed from echocardiograms prior but unrelated to the SCD event. Cases (n=418; 69.5±13.8 years), compared with controls (n=329; 67.7±11.9 years), more commonly had severe LV dysfunction (EF ≤35%; 30.5% versus 18.8%; P<0.01) and larger LV diameter (52.2±10.5 mm versus 49.7±7.9 mm; P<0.01). Moderate or severe LV dilatation (16.3% versus 8.2%; P=0.001) and severe LV dilatation (8.1% versus 2.1%; P<0.001) were significantly more frequent in cases. In multivariable analysis, severe LV dilatation was an independent predictor of SCD (odds ratio 2.5 [95% CI 1.03 to 5.9]; P=0.04). In addition, subjects with both EF ≤35% and severe LV dilatation had higher odds for SCD compared with those with low EF only (odds ratio 3.8 [95% CI 1.5 to 10.2] for both versus 1.7 [95% CI 1.2 to 2.5] for low EF only), suggesting that severe LV dilatation additively increased SCD risk. Conclusion LV diameter may contribute to risk stratification for SCD independent of the LVEF. This readily available echocardiographic measure warrants further prospective evaluation. PMID:25227407

  8. Cost of Czochralski wafers as a function of diameter

    SciTech Connect

    Leipold, M.H.; Radics, C.; Kachare, A.

    1980-02-15

    The impact of diameter in the range of 10 to 15 cm on the cost of wafers sliced from Czochralski ingots is analyzed. Increasing silicon waste and decreasing ingot cost with increasing ingot size are estimated along with projected costs. Results indicate a small but continuous decrease in sheet cost with increasing ingot size in this size range. Sheet costs including silicon are projected to be $50 to $60/m/sup 2/ (1980 $) depending upon technique used.

  9. Measuring angular diameter distances of strong gravitational lenses

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.

    2015-11-01

    The distance-redshift relation plays a fundamental role in constraining cosmological models. In this paper, we show that measurements of positions and time delays of strongly lensed images of a background galaxy, as well as those of the velocity dispersion and mass profile of a lens galaxy, can be combined to extract the angular diameter distance of the lens galaxy. Physically, as the velocity dispersion and the time delay give a gravitational potential (GM/r) and a mass (GM) of the lens, respectively, dividing them gives a physical size (r) of the lens. Comparing the physical size with the image positions of a lensed galaxy gives the angular diameter distance to the lens. A mismatch between the exact locations at which these measurements are made can be corrected by measuring a local slope of the mass profile. We expand on the original idea put forward by Paraficz and Hjorth, who analyzed singular isothermal lenses, by allowing for an arbitrary slope of a power-law spherical mass density profile, an external convergence, and an anisotropic velocity dispersion. We find that the effect of external convergence cancels out when dividing the time delays and velocity dispersion measurements. We derive a formula for the uncertainty in the angular diameter distance in terms of the uncertainties in the observables. As an application, we use two existing strong lens systems, B1608+656 (zL=0.6304) and RXJ1131-1231 (zL=0.295), to show that the uncertainty in the inferred angular diameter distances is dominated by that in the velocity dispersion, σ2, and its anisotropy. We find that the current data on these systems should yield about 16% uncertainty in DA per object. This improves to 13% when we measure σ2 at the so-called sweet-spot radius. Achieving 7% is possible if we can determine σ2 with 5% precision.

  10. Astronaut Assembly of a 14-Meter-Diameter Microwave Antenna

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Astronaut Jerry Ross is shown assembling a portion of a 14-meter-diameter truss structure in NASAs Neutral Buoyancy Simulator at the Marshall Space Flight Center. The structure is part of a large microwave antenna designed for space-based monitoring of soil moisture levels and ocean temperatures. The underwater assembly tests demonstrated that two astronauts could construct the large antenna in approximately 4-6 hours in space.

  11. Time-delay cosmography: increased leverage with angular diameter distances

    NASA Astrophysics Data System (ADS)

    Jee, I.; Komatsu, E.; Suyu, S. H.; Huterer, D.

    2016-04-01

    Strong lensing time-delay systems constrain cosmological parameters via the so-called time-delay distance and the angular diameter distance to the lens. In previous studies, only the former information was used in forecasting cosmographic constraints. In this paper, we show that the cosmological constraints improve significantly when the latter information is also included. Specifically, the angular diameter distance plays a crucial role in breaking the degeneracy between the curvature of the Universe and the time-varying equation of state of dark energy. Using a mock sample of 55 bright quadruple lens systems based on expectations for ongoing/future imaging surveys, we find that adding the angular diameter distance information to the time-delay distance information and the Planck's measurements of the cosmic microwave background anisotropies improves the constraint on the constant equation of state by 30%, on the time variation in the equation of state by a factor of two, and on the Hubble constant in the flat ΛCDM model by a factor of two. Therefore, previous forecasts for the statistical power of time-delay systems were overly pessimistic, i.e., time-delay systems are more powerful than previously appreciated.

  12. Diameter dependent thermoelectric properties of individual SnTe nanowires

    DOE PAGESBeta

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowiremore » diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.« less

  13. J-integral of circumferential crack in large diameter pipes

    NASA Astrophysics Data System (ADS)

    Ji, Wei; Chao, Yuh J.; Sutton, M. A.; Lam, P. S.; Mertz, G. E.

    Large diameter thin-walled pipes are encountered in a low pressure nuclear power piping system. Fracture parameters such as K and J, associated with postulated cracks, are needed to assess the safety of the structure, for example, prediction of the onset of tile crack growth and the stability of the crack. The Electric Power Research Institute (EPRI) has completed a comprehensive study of cracks in pipes and handbook-type data is available. However, for some large diameter, thin-walled pipes the needed information is not included in the handbook. This paper reports our study of circumferential cracks in large diameter, thin-walled pipes (R/t=30 to 40) under remote bending or tension loads. Elastic-Plastic analyses using the finite element method were performed to determine the elastic and fully plastic J values for various pipe/crack geometries. A non-linear Ramberg-Osgood material model is used with strain hardening exponents (n) that range from 3 to 10. A number of circumferential, through thickness cracks were studied with half crack angles ranging from 0.063(pi) to 0.5(pi). Results are tabulated for use with the EPRI estimation scheme.

  14. Mechanical analysis of conventional and small diameter conical implant abutments

    PubMed Central

    Moris, Izabela Cristina Maurício; Faria, Adriana Cláudia Lapria; de Mattos, Maria da Gloria Chiarello; Ribeiro, Ricardo Faria

    2012-01-01

    PURPOSE The aim of the present study was to evaluate if a smaller morse taper abutment has a negative effect on the fracture resistance of implant-abutment connections under oblique compressive loads compared to a conventional abutment. MATERIALS AND METHODS Twenty morse taper conventional abutments (4.8 mm diameter) and smaller abutments (3.8 mm diameter) were tightened (20 Ncm) to their respective implants (3.5 × 11 mm) and after a 10 minute interval, implant/abutment assemblies were subjected to static compressive test, performed in a universal test machine with 1 mm/min displacement, at 45° inclination. The maximum deformation force was determined. Data were statistically analyzed by student t test. RESULTS Maximum deformation force of 4.8 mm and 3.8 mm abutments was approximately 95.33 kgf and 95.25 kgf, respectively, but no fractures were noted after mechanical test. Statistical analysis demonstrated that the evaluated abutments were statistically similar (P=.230). CONCLUSION Abutment measuring 3.8 mm in diameter (reduced) presented mechanical properties similar to 4.8 mm (conventional) abutments, enabling its clinical use as indicated. PMID:22977724

  15. Diameter dependent thermoelectric properties of individual SnTe nanowires

    SciTech Connect

    Xu, E. Z.; Li, Z.; Martinez, J. A.; Sinitsyn, N.; Htoon, H.; Li, Nan; Swartzentruber, B.; Hollingsworth, J. A.; Wang, Jian; Zhang, S. X.

    2015-01-15

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a potentially promising thermoelectric material because of its similar electronic band structure as the well-known lead telluride. Here we report on the first thermoelectric study of individual single crystalline SnTe nanowires (NWs) with different diameters ranging from ~200 to ~1000 nm. Measurements of thermopower S, electrical conductivity σ, and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25 - 300 K. While σ does not show a strong diameter dependence, the thermopower increases by a factor of 2 when the nanowire diameter is decreased from 1000 nm to 200 nm. The thermal conductivities of the measured NWs are only about half of that of the bulk SnTe, which may arise from the enhanced phonon-grain boundary and phonon-defect scatterings. Temperature dependent figure-of-merit ZT was determined and the maximum value at room temperature is ~3 times higher than what was obtained in bulk samples of comparable carrier density.

  16. The method for detecting diffusion ring diameter in Hemagglutinin measuring

    NASA Astrophysics Data System (ADS)

    Jing, Wenbo; Liu, Xue; Duan, Jin; Wang, Xiao-man

    2014-11-01

    The diffuser ring diameter measurement is the most critical in hemagglutinin Measuring. The traditional methods, such as a vernier caliper or high-definition scanned images are subjective and low for the measurement data reliability. Propose high-resolution diffusion ring image for drop-resolution processing, adaptive Canny operator and local detection method to extract complete and clear diffusion ring boundaries, and finally make use of polynomial interpolation algorithm to make diffusion ring outer boundary pixel coordinates achieve sub-pixel accuracy and the least-squares fitting circle algorithm to calculate the precise center of the circle and the diameter of the diffuser ring. Experimental results show that the method detection time is only 63.61ms, which is a faster speed; diffuser ring diameter estimation error can achieve 0.55 pixel, high stability in experimental data. This method is adapted to the various types of influenza vaccine hemagglutinin content measurements, and has important value in the influenza vaccine quality detection.

  17. Diameter Dependent Thermoelectric Properties of Individual SnTe Nanowires

    NASA Astrophysics Data System (ADS)

    Xu, E. Z.; Li, Z.; Martinez, J.; Sinitsyn, N.; Htoon, H.; Li, N.; Swartzentruber, B.; Hollingsworth, J.; Wang, J.; Zhang, S. X.

    2015-03-01

    Tin telluride (SnTe), a newly discovered topological crystalline insulator, has recently been suggested to be a promising thermoelectric material. In this work, we report on a systematic study of the thermoelectric properties of individual single-crystalline SnTe nanowires with different diameters. Measurements of thermopower, electrical conductivity and thermal conductivity were carried out on the same nanowires over a temperature range of 25 - 300 K. While the electrical conductivity does not show a strong diameter dependence, we found that the thermopower increases by a factor of two when the nanowire diameter is decreased from 913 nm to 218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may be attributed to the enhanced phonon - surface boundary scattering and phonon-defect scattering. We further calculated the temperature dependent figure of merit ZT for each individual nanowire. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-AC04-94AL85000). We acknowledge support by the Los Alamos LDRD program.

  18. Tree height-diameter allometry across the United States.

    PubMed

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-03-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height-diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  19. Tree height–diameter allometry across the United States

    PubMed Central

    Hulshof, Catherine M; Swenson, Nathan G; Weiser, Michael D

    2015-01-01

    The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height–diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales. PMID:25859325

  20. Diameter dependent thermoelectric properties of individual SnTe nanowires.

    PubMed

    Xu, E Z; Li, Z; Martinez, J A; Sinitsyn, N; Htoon, H; Li, Nan; Swartzentruber, B; Hollingsworth, J A; Wang, Jian; Zhang, S X

    2015-02-21

    The lead-free compound tin telluride (SnTe) has recently been suggested to be a promising thermoelectric material. In this work, we report on the first thermoelectric study of individual single-crystalline SnTe nanowires with different diameters ranging from ∼218 to ∼913 nm. Measurements of thermopower S, electrical conductivity σ and thermal conductivity κ were carried out on the same nanowires over a temperature range of 25-300 K. While the electrical conductivity does not show a strong diameter dependence, the thermopower increases by a factor of two when the nanowire diameter is decreased from ∼913 nm to ∼218 nm. The thermal conductivity of the measured NWs is lower than that of the bulk SnTe, which may arise from the enhanced phonon - surface boundary scattering and phonon-defect scattering. Temperature dependent figure of merit ZT was determined for individual nanowires and the achieved maximum value at room temperature is about three times higher than that in bulk samples of comparable carrier density. PMID:25623253

  1. Subwavelength-diameter silica wires for microscale optical components

    NASA Astrophysics Data System (ADS)

    Tong, Limin; Mazur, Eric

    2005-04-01

    Subwavelength-diameter silica wires fabricated using a taper-drawing approach exhibit excellent diameter uniformity and atomic-level smoothness, making them suitable for low-loss optical wave guiding from the UV to the near-infrared. Such air-clad silica wires can be used as single-mode waveguides; depending on wavelength and wire diameter, they either tightly confine the optical fields or leave a certain amount of guided energy outside the wire in the form of evanescent waves. Using these wire waveguides as building blocks we assembled microscale optical components such as linear waveguides, waveguide bends and branch couplers on a low-index, non-dissipative silica aerogel substrate. These components are much smaller than comparable existing devices and have low optical loss, indicating that the wire-assembly technique presented here has great potential for developing microphotonics devices for future applications in a variety of fields such as optical communication, optical sensing and high-density optical integration.

  2. Unidirectional growth of benzil crystal from solution by Sankaranarayanan-Ramasamy method and its characterization.

    PubMed

    Rajalakshmi, M; Shyju, T S; Indirajith, R; Gopalakrishnan, R

    2012-02-01

    Good quality <100> benzil single crystal with a diameter 18 mm and length 75 mm was successfully grown from solution by the unidirectional growth method of Sankaranarayanan-Ramasamy (SR) for the first time in the literature. The seed crystals have been harvested from conventional solution growth technique and subsequently used for unidirectional growth. The grown crystal was subjected to various characterization studies. The results of UV-vis spectral analysis, photoluminescence, etching and microhardness studies were compared with conventional solution grown crystal to that of SR method grown crystal. The quality of SR method grown benzil crystal is better than conventional solution grown crystal. PMID:22088560

  3. Optical, dielectric and microhardness studies on <1 0 0> directed ADP crystal

    NASA Astrophysics Data System (ADS)

    Rajesh, P.; Ramasamy, P.

    2009-09-01

    <1 0 0> directed ammonium dihydrogen phosphate single crystal has been grown using the uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The size of the grown crystal is 40 mm in diameter and 50 mm in thickness. The grown crystals were characterized by UV-vis spectroscopy, Vickers hardness and dielectric studies. Comparing the <1 0 0> plane of the conventional method grown ADP crystal with <1 0 0> directed SR method grown ADP crystal, optical transparency, dielectric constant and Vickers hardness number are increased and dielectric loss is decreased in SR method grown crystal.

  4. Unidirectional growth of benzil crystal from solution by Sankaranarayanan-Ramasamy method and its characterization

    NASA Astrophysics Data System (ADS)

    Rajalakshmi, M.; Shyju, T. S.; Indirajith, R.; Gopalakrishnan, R.

    2012-02-01

    Good quality <1 0 0> benzil single crystal with a diameter 18 mm and length 75 mm was successfully grown from solution by the unidirectional growth method of Sankaranarayanan-Ramasamy (SR) for the first time in the literature. The seed crystals have been harvested from conventional solution growth technique and subsequently used for unidirectional growth. The grown crystal was subjected to various characterization studies. The results of UV-vis spectral analysis, photoluminescence, etching and microhardness studies were compared with conventional solution grown crystal to that of SR method grown crystal. The quality of SR method grown benzil crystal is better than conventional solution grown crystal.

  5. Suspended polymeric photonic crystals: simulation and fabrication

    NASA Astrophysics Data System (ADS)

    Rebigan, R.; Dinescu, A.; Kusko, C.; Gavrila, R.; Cristea, D.; Obreja, C.; Schiopu, P.

    2010-11-01

    In this paper we present simulation of transmission / reflection spectra of polymeric rectangular and hexagonal photonic crystals (PC) as well as the propagation of radiation in a hexagonal PC - based waveguide. The polymeric PC are periodic structures consisting in square arrays of holes configured in suspended membranes of PMMA with different diameters and pitch (100 nm diameter with 500 nm, respectively 800 nm pitch; 200 nm diameter with 500 nm pitch; 400 nm diameter with 700 nm pitch). For fabrication, we propose the bi-layer EBL technique based on simultaneous patterning of a bottom sacrificial layer (LOR 5A - Microchem Corporation) and a positive electron resist (PMMA of different molecular weights). Characterization of nanostructures was performed using SEM imaging and AFM measurements .

  6. Dependence of alpha particle track diameter on the free volume holes size using positron annihilation lifetime technique

    NASA Astrophysics Data System (ADS)

    El-Gamal, S.; Abdalla, Ayman M.; Abdel-Hady, E. E.

    2015-09-01

    The alpha particle track diameter dependence of the free volume holes size (Vf) in DAM-ADC and CR-39 nuclear track detectors was investigated using positron annihilation lifetime technique. The effect of temperature on the alpha particle track diameter and free volume were also investigated in the T-range (RT-130 °C). The obtained results revealed that the values of ortho-positronium lifetime τ3 and Vf increases while I3 slightly increases as T increases for the two detectors. The values of τ3, Vf and I3 are higher in CR-39 than DAM-ADC. The interpretation of obtained results is based on the fact that increasing T leads to significant enhancement of thermal expansion of the polymer matrix and consequently Vf increases. The track diameter increases as T increases. This can be explained by the fact that the increase in T increases the crystal size and Vf in the polymer. A relationship between Vf and the alpha particle track diameter was obtained. Moreover results of detector irradiation, along with free volume evaluation are addressed and thoroughly discussed.

  7. Estimating the Average Diameter of a Population of Spheres from Observed Diameters of Random Two-Dimensional Sections

    NASA Technical Reports Server (NTRS)

    Kong, Maiying; Bhattacharya, Rabi N.; James, Christina; Basu, Abhijit

    2003-01-01

    Size distributions of chondrules, volcanic fire-fountain or impact glass spherules, or of immiscible globules in silicate melts (e.g., in basaltic mesostasis, agglutinitic glass, impact melt sheets) are imperfectly known because the spherical objects are usually so strongly embedded in the bulk samples that they are nearly impossible to separate. Hence, measurements are confined to two-dimensional sections, e.g. polished thin sections that are commonly examined under reflected light optical or backscattered electron microscopy. Three kinds of approaches exist in the geologic literature for estimating the mean real diameter of a population of 3D spheres from 2D observations: (1) a stereological approach with complicated calculations; (2) an empirical approach in which independent 3D size measurements of a population of spheres separated from their parent sample and their 2D cross sectional diameters in thin sections have produced an array of somewhat contested conversion equations; and (3) measuring pairs of 2D diameters of upper and lower surfaces of cross sections each sphere in thin sections using transmitted light microscopy. We describe an entirely probabilistic approach and propose a simple factor of 4/x (approximately equal to 1.27) to convert the 2D mean size to 3D mean size.

  8. Characterization of Large Diameter PMTs for Kaon Cerenkov Detector

    NASA Astrophysics Data System (ADS)

    Boylan, Derek

    2014-09-01

    The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in particular as the aerogel refractive index decreases. The Hall C aerogel detector uses the Photonis XP4500 large-diameter photomultiplier tubes (PMT) in order to detect these small traces of light. The purpose of this project is to explore the performance of alternative large-diameter PMTs and compares them to that of the XP4500. The PMT uniformity across the photocathode was characterized through scans along the surface of the PMT with a low-intensity, focused LED, thereby creating a 3D image of the gain at each section. The method of scanning consists of a two axis step motor moving an LED light source on a 100 x 100 grid parallel to the face of the PMT, with 30 pulses of light from the LED at each step. The step motor scans with a resolution of 1.2 mm. Scans conducted in this manner result in high resolution images which pick up most sensitive/non-sensitive spots on the photocathode. In this presentation I will present the results of the characterization and performance test of the XP4500 and comparison to alternative large-diameter PMT models. The 12 GeV upgrade at the Jefferson Laboratory allows for unique new opportunities to study hadron structure through kaon production in Hall C, a threshold aerogel detector was constructed at the Catholic University of America. It uses the emission of Cerenkov radiation at different indices of refraction ranging from 1.03 to 1.01 to distinguish pions, kaons, and protons. An important aspect of this detector is the collection of very small amounts of light, in

  9. Suppression of phase transitions in a confined rodlike liquid crystal.

    PubMed

    Grigoriadis, Christos; Duran, Hatice; Steinhart, Martin; Kappl, Michael; Butt, Hans-Jürgen; Floudas, George

    2011-11-22

    The nematic-to-isotropic, crystal-to-nematic, and supercooled liquid-to-glass temperatures are studied in the liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) confined in self-ordered nanoporous alumina. The nematic-to-isotropic and the crystal-to-nematic transition temperatures are reduced linearly with the inverse pore diameter. The finding that the crystalline phase is completely suppressed in pores having diameters of 35 nm and below yields an estimate of the critical nucleus size. The liquid-to-glass temperature is reduced in confinement as anticipated by the model of rotational diffusion within a cavity. These results provide the pertinent phase diagram for a confined liquid crystal and are of technological relevance for the design of liquid crystal-based devices with tunable optical, thermal, and dielectric properties. PMID:21974835

  10. Europa's Surface Properties from Secondary Crater Depth/Diameter Ratios

    NASA Astrophysics Data System (ADS)

    Bierhaus, Edward B.; Chapman, C. R.; Schenk, P. M.

    2007-10-01

    We find that secondary craters on Europa tend towards smaller depth-to-diameter (d/D) ratios than primary craters, consistent with observations on other cratered surfaces (the Moon and Mars). We measure craters near the resolution limit, so an individual crater profile is noisy and not definitive; however, the aggregate statistics of over 100 profiles demonstrate a systematic trend for shallow profiles. Primary crater collapse from a simple bowl shape to a more shallow profile (or more complex morphology) is a function of material strength and surface gravity: the transition will happen at smaller diameters for weaker surfaces or for those with higher surface gravity. However, secondary craters are usually more shallow at a given diameter than a primary, perhaps due to lower fragment impact speeds or self-burial during multiple, simultaneous impacts (McEwen and Bierhaus 2005). To first order, very cold ice and rock respond similarly to impact cratering, with predictable differences due to differences in strength, equations of state, etc. But Europa's surface is enigmatic: pervasive fracturing suggests a solid, competent material; chaos features and mobility of blocks within chaos suggest fluid-like behavior; radar measurements (Black et al. 2001) support the presence of a porous surface layer, as do thermal inertia models (Spencer 2004) -- though the thermal inertia only addresses the uppermost few cm. The d/D similarity of secondary craters on icy Europa and rocky surfaces (the Moon and Mars), whose surface evolutions are dominated by different processes, implies that either (a) material properties play a small role in the morphology of secondary craters, or (b) whatever processes operate to create Europa's surface features must leave the ice in a form that responds to cratering in a manner consistent with regoliths on other solar system surfaces. NASA Outer Planets Program funds this research.

  11. Automatic segmentation and diameter measurement of coronary artery vessels

    NASA Astrophysics Data System (ADS)

    Zhao, Kun; Tang, Zhenyu; Pauli, Josef

    2011-03-01

    This work presents a hybrid method for 2D artery vessel segmentation and diameter measurement in X-Ray angiograms. The proposed method is novel in that tracking-based and model-based approaches are combined. A robust and efficient tracking template, the "annular template", is devised for vessel tracking. It can readily be applied on X-Ray angiograms without any preprocessing. Starting from an initial tracking point given by the user the tracking algorithm iteratively repositions the annular template and thereby detects the vessel boundaries and possible bifurcations. With a user selected end point the tracking process results in a set of points that describes the contour and topology of an artery vessel segment between the initial and end points. A "boundary correction and interpolation" operation refines the extracted points which initialize the Snakes algorithm. Boundary correction adjusts the points to ensure that they lie on the vessel segment of interest. Boundary interpolation adds more points, so that there are sufficiently many points for the Snakes algorithm to generate a smooth and accurate vessel segmentation. After the application of Snakes the resulting points are sequentially connected to represent the vessel contour. Then, the diameters are measured along the extracted vessel contour. The segmentation and measurement results are compared with manually extracted and measured vessel segments. The average Precision, Recall and Jaccard Index of 21 vessel samples are 91.5%, 92.1% and 84.9%, respectively. Compared with ground truth measurements of diameters the average relative error is 8.2%, and the average absolute error is 1.13 pixels.

  12. Development of Small Diameter Nanofiber Tissue Engineered Arterial Grafts

    PubMed Central

    Tara, Shuhei; Rocco, Kevin A.; Bagi, Paul S.; Yi, Tai; Udelsman, Brooks; Zhuang, Zhen W.; Cleary, Muriel; Iwakiri, Yasuko; Breuer, Christopher K.; Shinoka, Toshiharu

    2015-01-01

    The surgical repair of heart and vascular disease often requires implanting synthetic grafts. While synthetic grafts have been successfully used for medium-to-large sized arteries, applications for small diameter arteries (<6 mm) is limited due to high rates of occlusion by thrombosis. Our objective was to develop a tissue engineered vascular graft (TEVG) for small diameter arteries. TEVGs composed of polylactic acid nanofibers with inner luminal diameter between 0.5 and 0.6 mm were surgically implanted as infra-renal aortic interposition conduits in 25 female C17SCID/bg mice. Twelve mice were given sham operations. Survival of mice with TEVG grafts was 91.6% at 12 months post-implantation (sham group: 83.3%). No instances of graft stenosis or aneurysmal dilatation were observed over 12 months post-implantation, assessed by Doppler ultrasound and microCT. Histologic analysis of explanted TEVG grafts showed presence of CD31-positive endothelial monolayer and F4/80-positive macrophages after 4, 8, and 12 months in vivo. Cells positive for α-smooth muscle actin were observed within TEVG, demonstrating presence of smooth muscle cells (SMCs). Neo-extracellular matrix consisting mostly of collagen types I and III were observed at 12 months post-implantation. PCR analysis supports histological observations. TEVG group showed significant increases in expressions of SMC marker, collagen-I and III, matrix metalloproteinases-2 and 9, and itgam (a macrophage marker), when compared to sham group. Overall, patency rates were excellent at 12 months after implantation, as structural integrity of these TEVG. Tissue analysis also demonstrated vessel remodeling by autologous cell. PMID:25830942

  13. Fabricated nano-fiber diameter as liquid concentration sensors

    NASA Astrophysics Data System (ADS)

    Chyad, Radhi M.; Mat Jafri, Mohd Zubir; Ibrahim, Kamarulazizi

    Nanofiber is characterized by thin, long, and very soft silica. Taper fibers are made using an easy and low cost chemical method. Etching is conducted with a HF solution to remove cladding and then a low molarity HF solution to reduce the fiber core diameter. One approach to on-line monitoring of the etching process uses spectrophotometer with a white light source. In the aforementioned technique, this method aims to determine the diameter of the reduced core and show the evolution of the two different processes from the nanofiber regime to the fixed regime in which the mode was remote from the surrounding evanescent field, intensity can propagate outside the segment fiber when the core diameter is less than 500 nm. Manufacturing technologies of nano-fiber sensors offer a number of approved properties of optical fiber sensors utilized in various sensory applications. The nano-fiber sensor is utilized to sense the difference in the concentration of D-glucose in double-distilled deionized water and to measure the refractive index (RI) of a sugar solution. Our proposed method exhibited satisfactory capability based on bimolecular interactions in the biological system. The response of the nano-fiber sensors indicates a different kind of interaction among various groups of AAs. These results can be interpreted in terms of solute-solute and solute-solvent interactions and the structure making or breaking ability of solutes in the given solution. This study utilized spectra photonics to measure the transmission of light through different concentrations of sugar solution, employing cell cumber and nano-optical fibers as sensors.

  14. A solar cycle lengthwise series of solar diameter measurements

    NASA Astrophysics Data System (ADS)

    Penna, J. L.; Andrei, A. H.; Boscardin, S. C.; Neto, E. Reis; d'Ávila, V. A.

    2010-02-01

    The measurements of the solar photospheric diameter rank among the most difficult astronomic observations. Reasons for this are the fuzzy definition of the limb, the SNR excess, and the adverse daytime seeing condition. As a consequence there are very few lengthy and consistent time series of such measurements. Using modern techniques, just the series from the IAG/USP and from Calern/OCA span more than one solar cycle. The Rio de Janeiro Group observations started in 1997, and therefore in 2008 one complete solar cycle time span can be analyzed. The series shares common principles of observation and analysis with the ones afore mentioned, and it is complementary on time to them. The distinctive features are the larger number of individual points and the improved precision. The series contains about 25,000 single observations, evenly distributed on a day-by-day basis. The typical error of a single observation is half an arc-second, enabling us to investigate variations at the expected level of tens of arc-second on a weekly basis. These features prompted to develop a new methodology for the investigation of the heliophysical scenarios leading to the observed variations, both on time and on heliolatitude. The algorithms rely on running averages and time shifts to derive the correlation and statistical incertitude for the comparison of the long term and major episodes variations of the solar diameter against activity markers. The results bring support to the correlation between the diameter variation and the solar activity, but evidentiating two different regimens for the long term trend and the major solar events.

  15. SERS Raman Sensor Based on Diameter-Modulated Sapphire Fiber

    SciTech Connect

    Shimoji, Yutaka

    2010-08-09

    Surface enhanced Raman scattering (SERS) has been observed using a sapphire fiber coated with gold nano-islands for the first time. The effect was found to be much weaker than what was observed with a similar fiber coated with silver nanoparticles. Diameter-modulated sapphire fibers have been successfully fabricated on a laser heated pedestal growth system. Such fibers have been found to give a modest increase in the collection efficiency of induced emission. However, the slow response of the SERS effect makes it unsuitable for process control applications.

  16. Assembly of gold nanoparticles of different diameters between nanogap electrodes

    SciTech Connect

    Cheon, Donguk; Kumar, Sanjeev; Kim, Gil-Ho

    2010-01-04

    Gold nanoparticles (NPs) of different diameters i.e., 5, 10, and 20 nm, were assembled between 20 nm gap electrodes using ac dielectrophoresis (DEP) process. DEP parameters, such as frequency, trapping time, and voltage of value 1 MHz, 1 s, and 2-3 V, respectively, led to the pearl-chain assembly corresponding to each type of NPs between 20 nm gap electrodes. Mutual DEP could be attributed to the NPs chaining in low field regions and subsequently the DEP force directs these chains to the trapping region. Such controlled assembly of individual NPs may find application in fabricating devices for molecular electronics.

  17. Hoop tensile strength testing of small diameter ceramic particles

    NASA Astrophysics Data System (ADS)

    Wereszczak, A. A.; Jadaan, O. M.; Lin, H.-T.; Champoux, G. J.; Ryan, D. P.

    2007-03-01

    A method to measure hoop tensile strength of 1-mm-diameter brittle ceramic spheres was demonstrated through the use of a 'C-sphere' flexure strength specimen. This innovative specimen geometry was chosen because a simple, monotonically increasing uniaxial compressive force produces a hoop tensile stress at the C-sphere's outer surface that ultimately initiates fracture. This enables strength quantification and strength-limiting-flaw identification of the sphere itself. Such strength information is relevant to design optimization and durability assessments of ceramic fuel particles and breeder/multiplier pebbles for fusion when particle surfaces are subjected to tensile stresses during their manufacturing or service.

  18. Magnetic configurations in 160 520-nm-diameter ferromagnetic rings

    NASA Astrophysics Data System (ADS)

    Castaño, F. J.; Ross, C. A.; Eilez, A.; Jung, W.; Frandsen, C.

    2004-04-01

    The remanent states and hysteretic behavior of thin-film magnetic rings has been investigated experimentally and by micromagnetic modeling. Rings of diameters 160 520 nm, made from Co using lift-off processing, show three distinct remanent states: a vortex state, an “onion” state with two head-on walls, and a “twisted” state containing a 360° wall. The range of stability of these states varies with ring geometry, with smaller width rings showing higher switching fields and greater variability.

  19. Radio source orientation and the angular diameter-redshift relation

    SciTech Connect

    Onuora, L.I. )

    1991-08-01

    The effect of a nonrandom source orientation on the angular diameter-redshift relation was considered for the 3CR sample of Laing et al., based on the 'unified' scheme of Barthel. For an inhomogeneous sample of objects displaying milliarcsecond scale structure, it was found that there was no evidence for a systematic variation for orientation angle with redshift. However, if it was assumed that quasars are closer to the line of sight than powerful extended radio galaxies, then the observed angular size-redshift relation could be interpreted in terms of source orientation, rather than linear size evolution. 14 refs.

  20. Predicting the Tube Diameter in Melts and Solutions

    NASA Astrophysics Data System (ADS)

    Milner, Scott

    2004-03-01

    A simple conjecture relating chain dimensions to the so-called ``tube diameter'', which represents the topological confining effect of entanglements on a chain, works well for all flexible entangled polymer melts. I extend this conjecture to semidilute solutions: first for theta solvents, where it is shown to be equivalent to the Colby-Rubinstein scaling picture, and then for good solvents. In the latter case, it turns out that the number of ``blobs'' per entanglement strand B is not a constant as had been previously assumed, but depends on the ratio of the packing length to the Edwards length. This unified picture is in agreement with existing data on semidilute solutions.

  1. Note: Computer controlled rotation mount for large diameter optics

    NASA Astrophysics Data System (ADS)

    Rakonjac, Ana; Roberts, Kris O.; Deb, Amita B.; Kjærgaard, Niels

    2013-02-01

    We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

  2. Structure Optimization and Evaluation of Small Adjustable Diameter Grinding Wheel

    NASA Astrophysics Data System (ADS)

    Yao, Yiyong; Li, Yuanyuan; Zhao, Liping; Zhao, Hu

    Focus on the uneven deformation of conventional adjustable diameter grinding wheel (ADGW), a structure optimization and evaluation method of ADGW was proposed in this paper. Firstly, the evaluation index system and structure optimization framework of ADGW was established to obtain the optimization objective of ADGW. Then a simulated experiment was provided. The flexible units of ADGW with different structures and geometries were selected to analyze the unevenness of deformation. The comparison results showed that the proposed method can improve the ADGW structures effectively and provide a technical approach for evaluating the structure design of ADGW.

  3. Tracking of vessel diameter fluctuations using digital image analysis

    NASA Astrophysics Data System (ADS)

    Aggarwal, Shanti J.; Yip, C.-Y.; Diller, Kenneth R.; Bovik, Alan C.

    1990-05-01

    An automatic digital image processing technique for vasomotion analysis in peripheral microcirculation at multiple sites simultaneously and in real time, is presented. The algorithm utilizes either fluorescent or bright field microimages of the vasculature as input. The video images are digitized and analyzed on-line by an IBM RT PC. Using digital filtering and edge detection, the technique allows simultaneous diameter measurement at more than one site. The sampling frequency is higher than 5 Hz when only one site is tracked. The performance of the algorithm is tested in the hamster cutaneous microcirculation.

  4. Growth of large size <1 1 0> benzophenone crystal using uniaxially solution-crystallization method of Sankaranarayanan Ramasamy (SR)

    NASA Astrophysics Data System (ADS)

    Sankaranarayanan, K.

    2005-10-01

    <1 1 0> benzophenone single crystal of diameter 60 mm and length 50 mm was successfully grown by SR method using a seed fixed at the bottom of the ampoule. The obtained cylindrical morphology, solute-crystal conversion efficiency of 100%, growth at room temperature, less-sophisticated experimental set-up employed, growth in a chosen direction, possibility for avoidance of microbial growth and ease in scaling up of diameter are the vital advantages of this technique towards the growth of phase-matched SHG crystal for device application. The grown benzophenone crystal was characterized by XRD, phase-matching study and laser damage threshold measurement. The results evidence the suitability of this method for unidirectional growth of bulk single crystal.

  5. Weak crystallization theory of metallic alloys

    NASA Astrophysics Data System (ADS)

    Martin, Ivar; Gopalakrishnan, Sarang; Demler, Eugene A.

    2016-06-01

    Crystallization is one of the most familiar, but hardest to analyze, phase transitions. The principal reason is that crystallization typically occurs via a strongly first-order phase transition, and thus rigorous treatment would require comparing energies of an infinite number of possible crystalline states with the energy of liquid. A great simplification occurs when crystallization transition happens to be weakly first order. In this case, weak crystallization theory, based on unbiased Ginzburg-Landau expansion, can be applied. Even beyond its strict range of validity, it has been a useful qualitative tool for understanding crystallization. In its standard form, however, weak crystallization theory cannot explain the existence of a majority of observed crystalline and quasicrystalline states. Here we extend the weak crystallization theory to the case of metallic alloys. We identify a singular effect of itinerant electrons on the form of weak crystallization free energy. It is geometric in nature, generating strong dependence of free energy on the angles between ordering wave vectors of ionic density. That leads to stabilization of fcc, rhombohedral, and icosahedral quasicrystalline (iQC) phases, which are absent in the generic theory with only local interactions. As an application, we find the condition for stability of iQC that is consistent with the Hume-Rothery rules known empirically for the majority of stable iQC; namely, the length of the primary Bragg-peak wave vector is approximately equal to the diameter of the Fermi sphere.

  6. The Use of Narrow Diameter Implants in the Molar Area.

    PubMed

    Saad, M; Assaf, A; Gerges, E

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  7. Diameter Dependence of Planar Defects in InP Nanowires.

    PubMed

    Wang, Fengyun; Wang, Chao; Wang, Yiqian; Zhang, Minghuan; Han, Zhenlian; Yip, SenPo; Shen, Lifan; Han, Ning; Pun, Edwin Y B; Ho, Johnny C

    2016-01-01

    In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications. PMID:27616584

  8. Polymer scaffolds for small-diameter vascular tissue engineering.

    PubMed

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2010-09-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  9. Polymer scaffolds for small-diameter vascular tissue engineering

    PubMed Central

    Ma, Haiyun; Hu, Jiang; Ma, Peter X

    2014-01-01

    To better engineer small-diameter blood vessels, a few types of novel scaffolds were fabricated from biodegradable poly(L-lactic acid) (PLLA) by means of thermally induced phase separation (TIPS) techniques. By utilizing the differences in thermal conductivities of the mold materials, the scaffolds with oriented gradient microtubular structures in axial or radial direction were created using benzene as the solvent. The porosity, tubular size, and the orientation direction of the microtubules can be controlled by polymer concentration, TIPS temperature, and materials of different thermal conductivities. The gradient microtubular structure was intended to facilitate cell seeding and mass transfer for cell growth and function. We also developed nanofibrous scaffolds with oriented and interconnected micro-tubular pore network by a one-step TIPS method using benzene/tetrahydrofuran mixture as the solvent without using porogen materials. The structural features of such scaffolds can be conveniently adjusted by varying the solvent ratio, phase separation temperature and polymer concentration to mimic the nanofibrous feature of extracellular matrix. These scaffolds were fabricated for the tissue engineering of small-diameter blood vessels by utilizing their advantageous structural features to facilitate blood vessel regeneration. PMID:24501590

  10. The Use of Narrow Diameter Implants in the Molar Area

    PubMed Central

    Saad, M.; Assaf, A.; Gerges, E.

    2016-01-01

    Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm) or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm) could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence. PMID:27293436

  11. 33-Foot-Diameter Space Station Leading to Space Base

    NASA Technical Reports Server (NTRS)

    1969-01-01

    This picture illustrates a concept of a 33-Foot-Diameter Space Station Leading to a Space Base. In-house work of the Marshall Space Flight Center, as well as a Phase B contract with the McDornel Douglas Astronautics Company, resulted in a preliminary design for a space station in 1969 and l970. The Marshall-McDonnel Douglas approach envisioned the use of two common modules as the core configuration of a 12-man space station. Each common module was 33 feet in diameter and 40 feet in length and provided the building blocks, not only for the space station, but also for a 50-man space base. Coupled together, the two modules would form a four-deck facility: two decks for laboratories and two decks for operations and living quarters. Zero-gravity would be the normal mode of operation, although the station would have an artificial gravity capability. This general-purpose orbital facility was to provide wide-ranging research capabilities. The design of the facility was driven by the need to accommodate a broad spectrum of activities in support of astronomy, astrophysics, aerospace medicine, biology, materials processing, space physics, and space manufacturing. To serve the needs of Earth observations, the station was to be placed in a 242-nautical-mile orbit at a 55-degree inclination. An Intermediate-21 vehicle (comprised of Saturn S-IC and S-II stages) would have launched the station in 1977.

  12. Diameter of titanium nanotubes influences anti-bacterial efficacy

    NASA Astrophysics Data System (ADS)

    Ercan, Batur; Taylor, Erik; Alpaslan, Ece; Webster, Thomas J.

    2011-07-01

    Bacterial infection of in-dwelling medical devices is a growing problem that cannot be treated by traditional antibiotics due to the increasing prevalence of antimicrobial resistance and biofilm formation. Here, due to changes in surface parameters, it is proposed that bacterial adhesion can be prevented through nanosurface modifications of the medical device alone. Toward this goal, titanium was created to possess nanotubular surface topographies of highly controlled diameters of 20, 40, 60, or 80 nm, sometimes followed by heat treatment to control chemistry and crystallinity, through a novel anodization process. For the first time it was found that through the control of Ti surface parameters including chemistry, crystallinity, nanotube size, and hydrophilicity, significantly changed responses of both Staphylococcus epidermidis and Staphylococcus aureus (pathogens relevant for orthopaedic and other medical device related infections) were measured. Specifically, heat treatment of 80 nm diameter titanium tubes produced the most robust antimicrobial effect of all surface treatment parameters tested. This study provides the first step toward understanding the surface properties of nano-structured titanium that improve tissue growth (as has been previously observed with nanotubular titanium), while simultaneously reducing infection without the use of pharmaceutical drugs.

  13. Allowable pillar to diameter ratio for strategic petroleum reserve caverns.

    SciTech Connect

    Ehgartner, Brian L.; Park, Byoung Yoon

    2011-05-01

    This report compiles 3-D finite element analyses performed to evaluate the stability of Strategic Petroleum Reserve (SPR) caverns over multiple leach cycles. When oil is withdrawn from a cavern in salt using freshwater, the cavern enlarges. As a result, the pillar separating caverns in the SPR fields is reduced over time due to usage of the reserve. The enlarged cavern diameters and smaller pillars reduce underground stability. Advances in geomechanics modeling enable the allowable pillar to diameter ratio (P/D) to be defined. Prior to such modeling capabilities, the allowable P/D was established as 1.78 based on some very limited experience in other cavern fields. While appropriate for 1980, the ratio conservatively limits the allowable number of oil drawdowns and hence limits the overall utility and life of the SPR cavern field. Analyses from all four cavern fields are evaluated along with operating experience gained over the past 30 years to define a new P/D for the reserve. A new ratio of 1.0 is recommended. This ratio is applicable only to existing SPR caverns.

  14. Measurements of Pupillary Diameter and Wavefront Aberrations in Pregnant Women

    PubMed Central

    Altay, Mehmet Metin; Demirok, Gulizar; Balta, Ozgur; Bolu, Hulya

    2016-01-01

    Purpose. To show whether pregnancy affects the measurements of pupillary diameter and wavefront (WF) aberrations. Methods. This was a case-control study including 34 healthy pregnant women in the third trimester and age-matched 34 nonpregnant women. Only women who had no ocular abnormalities and no refractive error were included. We measured photopic and mesopic pupil diameter and WF aberrations at the third trimester and at the second postpartum month. Measurements of the right eyes were used in this study. The differences between groups were analysed by paired t-test and t-test. Results. Pregnant women's mean photopic pupil size in the third trimester was significantly higher than in postpartum period and in control group (3.74 ± 0.77, 3.45 ± 0.53, and 3.49 ± 0.15 mm, p < 0.05, resp.). Mesopic pupil size in the third trimester was also higher than in postpartum period and in control group (6.77 ± 0.52, 6.42 ± 0.55, and 6.38 ± 0.21 mm, p < 0.05, resp.). RMS-3 and RMS-5 values were higher in pregnancy but these differences were not statistically significant. Conclusion. Pregnancy increased photopic and mesopic pupil size significantly but did not increase wavefront aberrations notably. Increased pupil size may be due to increased sympathetic activity during pregnancy. And this activity can be noninvasively determined by measuring pupil size. PMID:26998383

  15. Large diameter femoral heads: is bigger always better?

    PubMed

    Cooper, H J; Della Valle, C J

    2014-11-01

    Dislocation remains among the most common complications of, and reasons for, revision of both primary and revision total hip replacements (THR). Hence, there is great interest in maximising stability to prevent this complication. Head size has been recognised to have a strong influence on the risk of dislocation post-operatively. As femoral head size increases, stability is augmented, secondary to an increase in impingement-free range of movement. Larger head sizes also greatly increase the 'jump distance' required for the head to dislocate in an appropriately positioned cup. Level-one studies support the use of larger diameter heads as they decrease the risk of dislocation following primary and revision THR. Highly cross-linked polyethylene has allowed us to increase femoral head size, without a marked increase in wear. However, the thin polyethylene liners necessary to accommodate larger heads may increase the risk of liner fracture and larger heads have also been implicated in causing soft-tissue impingement resulting in groin pain. Larger diameter heads also impart larger forces on the femoral trunnion, which may contribute to corrosion, metal release, and adverse local tissue reactions. Alternative large bearings including large ceramic heads and dual mobility bearings may mitigate some of these risks, and several of these devices have been used with clinical success. PMID:25381403

  16. Curvature-directed crystallization of isotactic poly(propylene) in nanopores

    NASA Astrophysics Data System (ADS)

    Reid, Dariya; Ehlinger, Bridget; Lutkenhaus, Jodie

    2013-03-01

    Properties of a cylindrically confined polymer may greatly differ from its properties in bulk state when the geometrical restrictions approach the size of the polymer itself. Confinement of polymer dielectrics, such as isotactic polypropylene (iPP), in nanoporous templates can potentially enhance the dielectric properties of the material via directed crystallization. iPP was melt-wetted into nanoporous templates of varying diameter (15 - 200 nm) in order to study the effect of pore dimensions on crystallization. Using differential scanning calorimetry (DSC) and X-ray diffraction (XRD), it is shown that iPP crystallizes into the α-phase and preferentially orients along the long axis pore. A transition from hetero to homogeneous crystallization was observed in relation to pore diameter. The isothermal crystallization kinetics was analyzed using Avrami analysis. As the pore diameter decreases crystallization shifts to a multi-mode process, whose origins will be discussed in this presentation. This work has been supported by ACS PRF.

  17. Crystal growth and detector performance of large size high-purity Ge crystals

    NASA Astrophysics Data System (ADS)

    Wang, Guojian; Amman, Mark; Mei, Hao; Mei, Dongming; Irmscher, Klaus; Guan, Yutong; Yang, Gang

    2015-03-01

    High-purity germanium crystals with 12 cm in diameter were grown in a hydrogen atmosphere using the Czochralski method. The dislocation density of the crystals was determined to be in the range of 2000 - 4200 cm-2, which meets a requirement for use as a radiation detector. The axial and radial distributions of impurities in the crystals were measured by Hall effect and Photo-thermal ionization spectroscopy (PTIS). Two detectors were also fabricated from one of the crystals with different techniques and then evaluated for electrical and spectral performance. Measurements of gamma-ray spectra from 137Cs, 241Am and 60Co sources demonstrate that the detectors have excellent energy resolution. Keywords: High-purity germanium crystal, Czochralski method This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  18. Development of methods of producing large areas of silicon sheet by the slicing of silicon ingots using Inside-Diameter (I.D.) saws

    NASA Technical Reports Server (NTRS)

    Aharonyan, P.

    1980-01-01

    Inside diametar wafering equipment, blades and processes were used to develop methods to produce large areas of silicon sheet. Modifications to a 16 inch STC automated saw included: programmable feed system, crystal rotating system, and STC dynatrack blade monitoring and control system. By controlling the plating operation and by grinding of the cutting edge, 16 inch ID blades with a cutting edge thickness of .22 mm can be produced. Crystal rotation mechanism was used to slice 100 mm diameter crystals with a 16 inch blade down to a thickness of .20 mm. Cutting rates with crystal rotation were generally slower than with standard plunge ID slicing techniques. Using programmed feeds and programmed rotation, maximum cutting rates were from 0.3 to 1.0 inches per minute.

  19. Development of methods of producing large areas of silicon sheet by the slicing of silicon ingots using Inside Diameter (I.D.) saws

    NASA Technical Reports Server (NTRS)

    Aharonyan, P.

    1980-01-01

    Modifications to a 16 inch STC automated saw included: a programmable feed system; a crystal rotating system; and a STC dynatrack blade boring and control system. By controlling the plating operation and by grinding the cutting edge, 16 inch I.D. blades were produced with a cutting edge thickness of .22 mm. Crystal rotation mechanism was used to slice 100 mm diameter crystals with a 16 inch blade down to a thickness of .20 mm. Cutting rates with crystal rotation were generally slower than with standard plunge I.D. slicing techniques. Using programmed feeds and programmed rotation, maximum cutting rates were from 0.3 to 1.0 inches per minute.

  20. Mechanical testing of large thallium doped sodium iodide single crystals

    NASA Technical Reports Server (NTRS)

    Lee, H. M.

    1985-01-01

    The findings of mechanical tests performed on five thallium-doped sodium iodide NaI(Tl) crystals are presented. These crystals are all in the shape of circular flat plates, 20.0 in. in diameter an d0.5 in. thick. The test setup, testing procedure, and the test data are presented. Large crystals exhibit a high degree of material plasticity, as well as a much higher strength than previously anticipated, on the order of 500 psi. Also revealed from the testing is the fact that crystal with a large number of grain boundaries developed less plasticity, and therefore less permanent deformation, than those with fewer grain boundaries.

  1. Optical diagnostics of solution crystal growth

    NASA Technical Reports Server (NTRS)

    Kim, Yongkee; Reddy, B. R.; George, Tharayil G.; Lal, Ravindra B.

    1995-01-01

    Solution crystal growth monitoring of LAP/TGS crystals by various optical diagnostics systems, such as conventional and Mach-Zehnder (M-Z) interferometers, optical heterodyne technique, and ellipsometry, is under development. The study of the dynamics of the crystal growth process requires a detailed knowledge of crystal growth rate and the concentration gradient near growing crystals in aqueous solution. Crystal growth rate can be measured using conventional interferometry. Laser beam reflections from the crystal front as well as the back surface interfere with each other, and the fringe shift due to the growing crystal yields information about the growth rate. Our preliminary results indicate a growth rate of 6 A/sec for LAP crystals grown from solution. Single wavelength M-Z interferometry is in use to calculate the concentration gradient near the crystal. Preliminary investigation is in progress using an M-Z interferometer with 2 cm beam diameter to cover the front region of the growing crystal. In the optical heterodyne technique, phase difference between two rf signals (250 KHZ) is measured of which one is a reference signal, and the other growth signal, whose phase changes due to a change in path length as the material grows. From the phase difference the growth rate can also be calculated. Our preliminary results indicate a growth rate of 1.5 A/sec. the seed and solution temperatures were 26.46 C and 27.92 C respectively, and the solution was saturated at 29.0 C. an ellipsometer to measure the growth rate and interface layer is on order from JOBIN YVON, France. All these systems are arranged in such a manner that measurements can be made either sequentially or simultaneously. These techniques will be adapted for flight experiment.

  2. Crystallization Physics in Biomacromolecular Systems

    NASA Technical Reports Server (NTRS)

    Chernov, A. A.

    2003-01-01

    The crystals are built of molecules of protein, nucleic acid and their complexes, like viruses, approx. 5x10(exp 3)+ 3x10(exp 6) Da in weight and 2 + 20 nm in effective diameter. This size strongly exceeds action range of molecular forces and makes a big difference with inorganic crystals. Intermolecular contacts form patches on the biomacromolecular surface. Each patch may occupy only a small percent of the whole surface and vary from polymorph to polymorph of the same protein. Thus, under different conditions (pH, solution chemistry, temperature, any area on the macromolecular surface may form a contact. The crystal Young moduli, E approx. equals 0.1 + 0.5 GPa are more than 10 times lower than that of inorganics and the biomolecules themselves. Water within biocrystals (30-70%) is unable to flow unless typical deformation time is longer than approx. 10(exp -5)s. This explains the discrepancy between light scattering and static measurements of E. Nucleation and Growth requires typically concentrations exceeding the equilibrium ones up to 100 times - because of the new size scale results in 10 - 10(exp 3) times lower kinetic coefficients than that needed for inorganic solution growth. All phenomena observed in the latter occur with protein crystallization and are even better studied by AFM. Crystals are typically facetted. Among unexpected findings of general significance are - net molecular exchange flux at kinks is much lower than that expected from supersaturation, steps with low (< approx. 10(exp -2)) kink density at steps follow Gibbs-Thomson law only at very low supersaturations, step segment growth rate may be independent of step energy. Crystal perfection is a must of biocrystallization to achieve the major goal to find 3-D atomic structure of biomacromolecules by x-ray diffraction. Poor diffraction resolution (> 3Angstrom) makes crystallization a bottleneck for structural biology. All defects typical of small molecule crystals are found in biocrystals, but

  3. A Small Diameter Rosette for Sampling Ice Covered Waters

    NASA Astrophysics Data System (ADS)

    Chayes, D. N.; Smethie, W. M.; Perry, R. S.; Schlosser, P.; Friedrich, R.

    2011-12-01

    A gas tight, small diameter, lightweight rosette, supporting equipment and an effective operational protocol has been developed for aircraft supported sampling of sea water across the Lincoln Sea. The system incorporates a commercial off the shelf CTD electronics (SBE19+ sensor package and SBE33 deck unit) to provide real-time measurement data at the surface. We designed and developed modular water sample units and custom electronics to decode the bottle firing commands and close the sample bottles. For a typical station, we land a ski-equipped deHaviland Twin Otter (DHC-6) aircraft on a suitable piece of sea-ice, drill a 12" diameter hole through the ice next to the cargo door and set up a tent to provide a reasonable working environment over the hole. A small winch with 0.1" diameter single conductor cable is mounted in the aircraft by the cargo door and a tripod supports a sheave above the hole. The CTD module is connected to the end of the wire and the water sampling modules are stacked on top as the system is lowered. For most stations, three sample modules are used to provide 12 four (4) liter sample bottles. Data collected during the down-cast is used to formulate the sampling plan which is executed on the up-cast. The system is powered by a 3,700 Watt, 120VAC gasoline generator. After collection, the sample modules are stored in passively temperature stabilized ice chests during the flight back to the logistics facility at Alert where a broad range of samples are drawn and stored for future analysis. The transport mechanism has a good track record of maintaining water samples within about two degrees of the original collection temperature which minimizes out-gassing. The system has been successfully deployed during a field program each spring starting in 2004 along a transect between the north end of Ellesmere Island (Alert, Nunavut) and the North Pole. During the eight field programs we have taken 48 stations with twelve bottles at most stations (eight at

  4. Synthesis of monodisperse mesoporous titania beads with controllable diameter, high surface areas, and variable pore diameters (14-23 nm).

    PubMed

    Chen, Dehong; Cao, Lu; Huang, Fuzhi; Imperia, Paolo; Cheng, Yi-Bing; Caruso, Rachel A

    2010-03-31

    Monodisperse mesoporous anatase titania beads with high surface areas and tunable pore size and grain diameter have been prepared through a combined sol-gel and solvothermal process in the presence of hexadecylamine (HDA) as a structure-directing agent. The monodispersity of the resultant titania beads, along with the spherical shape, can be controlled by varying the amount of structure-directing agent involved in the sol-gel process. The diameter of the titania beads is tunable from approximately 320 to 1150 nm by altering the hydrolysis and condensation rates of the titanium alkoxide. The crystallite size, specific surface area (from 89 to 120 m(2)/g), and pore size distribution (from 14 to 23 nm) of the resultant materials can be varied through a mild solvothermal treatment in the presence of varied amounts of ammonia. On the basis of the results of small-angle XRD, high-resolution SEM/TEM, and gas sorption characterization, a mechanism for the formation of the monodisperse precursor beads has been proposed to illustrate the role of HDA in determining the morphology and monodispersity during the sol-gel synthesis. The approach presented in this study demonstrates that simultaneous control of the physical properties, including specific surface area, mesoporosity, crystallinity, morphology, and monodispersity, of the titania materials can be achieved by a facile sol-gel synthesis and solvothermal process. PMID:20201515

  5. HVOF thermal spray process for internal diameter applications

    SciTech Connect

    Poe, M.W.

    1994-12-31

    Thermal spray has been selected as the coating process of choice for many OEM and repair/restoration applications. Although the thermal spray process has historically been limited to coating `line-of-sight` surfaces, advances in thermal spray equipment design now allow protective and/or restorative coatings to be applied to deep internal diameters utilizing state-of-the-art HVOF processing. The advanced designs include both `standard` and `mini` torches to coat rotating components, plus a rotating extension for coating stationary ID`s. In addition, a wide range of coating materials has been developed and engineered to combat the deleterious effects of wear found in severe service environments. The resultant coatings have exceptionally high bond strength with no interconnected porosity and low residual stress. This unique process provides an important adjunct to the field of thermal spray process capabilities.

  6. Longitudinal Lorentz force on a subwavelength-diameter optical fiber

    SciTech Connect

    Yu Huakang; Fang Wei; Gu Fuxing; Yang Zongyin; Tong Limin; Qiu Min

    2011-05-15

    We analyze the longitudinal Lorentz forces that a propagating continuous-wave light exerts on a subwavelength-diameter optical fiber. Our theoretical results show that, during the propagating process, the guided light exerts no net time-averaged force on the fiber. Via numerical simulation, we find a significant overall pull force of 0.4 pN/mW acting on a 450-nm-diam fiber tip at a wavelength of 980 nm due to the scattering of the end face and a calculated force distribution reveals the feature of a near-field accumulation. Our results may be helpful to the configuration of optomechanical components or devices based on these fibers.

  7. Density profile control in a large diameter, helicon plasma

    SciTech Connect

    Cluggish, B.P.; Anderegg, F.A.; Freeman, R.L.; Gilleland, J.; Hilsabeck, T.J.; Isler, R.C.; Lee, W.D.; Litvak, A.A.; Miller, R.L.; Ohkawa, T.; Putvinski, S.; Umstadter, K.R.; Winslow, D.L.

    2005-05-15

    Plasmas with peaked radial density profiles have been generated in the world's largest helicon device, with plasma diameters of over 70 cm. The density profiles can be manipulated by controlling the phase of the current in each strap of two multistrap antenna arrays. Phase settings that excite long axial wavelengths create hollow density profiles, whereas settings that excite short axial wavelengths create peaked density profiles. This change in density profile is consistent with the cold-plasma dispersion relation for helicon modes, which predicts a strong increase in the effective skin depth of the rf fields as the wavelength decreases. Scaling of the density with magnetic field, gas pressure, and rf power is also presented.

  8. White matter microstructure from nonparametric axon diameter distribution mapping.

    PubMed

    Benjamini, Dan; Komlosh, Michal E; Holtzclaw, Lynne A; Nevo, Uri; Basser, Peter J

    2016-07-15

    We report the development of a double diffusion encoding (DDE) MRI method to estimate and map the axon diameter distribution (ADD) within an imaging volume. A variety of biological processes, ranging from development to disease and trauma, may lead to changes in the ADD in the central and peripheral nervous systems. Unlike previously proposed methods, this ADD experimental design and estimation framework employs a more general, nonparametric approach, without a priori assumptions about the underlying form of the ADD, making it suitable to analyze abnormal tissue. In the current study, this framework was used on an ex vivo ferret spinal cord, while emphasizing the way in which the ADD can be weighted by either the number or the volume of the axons. The different weightings, which result in different spatial contrasts, were considered throughout this work. DDE data were analyzed to derive spatially resolved maps of average axon diameter, ADD variance, and extra-axonal volume fraction, along with a novel sub-micron restricted structures map. The morphological information contained in these maps was then used to segment white matter into distinct domains by using a proposed k-means clustering algorithm with spatial contiguity and left-right symmetry constraints, resulting in identifiable white matter tracks. The method was validated by comparing histological measures to the estimated ADDs using a quantitative similarity metric, resulting in good agreement. With further acquisition acceleration and experimental parameters adjustments, this ADD estimation framework could be first used preclinically, and eventually clinically, enabling a wide range of neuroimaging applications for improved understanding of neurodegenerative pathologies and assessing microstructural changes resulting from trauma. PMID:27126002

  9. Evaluation of small diameter coreholes for reservoir information

    SciTech Connect

    Petty, Susan; Adair, Richard G.; Livesay, Bill

    1992-01-01

    Geothermal exploration has been highly successful to date in locating targets for drilling. However, the requirements for an economically successful geothermal well are both high flow rate and high temperature. Most geophysical and geochemical exploration methods have not been highly accurate in predicting the depth and actual temperature of a reservoir, nor have they been able to locate high permeability zones. The result is that most geothermal exploration is conducted by drilling core holes to better understand the heat flow in an area followed by drilling of production diameter exploration wells which can be flow tested to ascertain the permeability. The goal of any exploration program is to determine reservoir economics. The cost of wells makes up between one quarter and one half the total cost of producing geothermal power. The number, design, depth of wells and placement of injectors are important to the optimal exploitation of the reservoir. Although early efforts at development have focused on rapid plant construction to begin cash flow, the history of producing fields emphasizes that understanding reservoirs can reduce the risk of rapid temperature or pressure declines and increase the success of step out drilling following initial exploitation. The high cost of large diameter production wells makes the collecting of exploration data on the reservoir through some less expensive method desirable. Geothermal developers are still drilling resources with surface expression, hot springs and surface mappable fractures and faults. As these obvious resources are developed and as the obvious targets in productive fields are exhausted, new exploration tools are needed. One possibility is the use of deep core holes drilled for temperature gradient data to provide more reservoir information. Two methods not previously applied to geothermal reservoir assessment are suggested to augment other data obtained from coreholes.

  10. Automatic detection and estimation of biparietal diameter from fetal ultrasonography

    NASA Astrophysics Data System (ADS)

    Annangi, Pavan; Banerjee Krishnan, Kajoli; Banerjee, Jyotirmoy; Gupta, Madhumita; Patil, Uday

    2011-03-01

    Fetal bi-parietal diameter (BPD) is known to provide a reliable estimate of gestational age (GA) of a fetus in the first half of pregnancy. In this paper, we present an automated method to identify and measure BPD from B-mode ultrasound images of fetal head. The method (a) automatically detects and places a region-of-interest on the head based on a prior work in our group (b) utilizes the concept of phase congruency for edge detection and (c) employs a cost function to identify the third ventricle inside the head (d) measures the BPD along the perpendicular bisector of occipital frontal diameter (OFD) from the outer rim of the cranium closer to the transducer to the inner rim of the cranium away from the transducer. The cost function is premised on the distribution of anatomical shape, size and presentation of the third ventricle in images that adhere to clinical guidelines describing the scan plane for BPD measurement. The OFD is assumed to lie along the third ventricle. The algorithm has been tested on 137 images acquired from four different scanners. Based on GA estimates and their bounds specified in Standard Obstetric Tables, the GA predictions from automated measurements are found to be within +/-2SD of GA estimates from manual measurements by the operator and a second expert radiologist in 98% of the cases. The method described in this paper can also be adapted to assess the accuracy of the scan plane based on the presence/absence of the third ventricle.

  11. Decellularized ovine arteries as small-diameter vascular grafts.

    PubMed

    Mancuso, L; Gualerzi, A; Boschetti, F; Loy, F; Cao, G

    2014-08-01

    Atherosclerosis and its complications still represent the leading cause of death in the developed countries. While autologous blood vessels may be regarded as the best solution for peripheral and coronary bypass, they are unavailable in most patients. Even though tissue engineering techniques are often applied to the development of small-diameter vascular grafts, limiting factors of this approach are represented by the lack of essential extracellular matrix proteins and/or poor biomechanical properties of the scaffolds used. Along these lines, the aim of this study was to develop a decellularization protocol for ovine carotids to be used as suitable small-diameter vascular grafts. Samples were treated either with sodium dodecyl sulphate (SDS) or with Trypsin and Triton X-100; a final nuclease digestion was performed for both protocols. Morphological analyses demonstrate complete removal of nuclei and cellular components in treated vessels, also confirmed by significant reduction in wall thickness and DNA content. Essential extracellular matrix proteins such as collagen, elastin, and fibronectin are well preserved after decellularization. From a mechanical point of view, Trypsin and Triton X-100 treated arteries show elastic modules and compliance comparable to native carotids, whereas the use of SDS makes samples stiffer, with a significant decrease in the compliance mean value and an increase in longitudinal and circumferential Young's modules. It is demonstrated that the treatment where Trypsin and Triton X-100 are combined guarantees complete decellularization of carotids, with no significant alteration of biomechanical and structural properties, thus preserving a suitable environment for adhesion, proliferation, and migration of cells. PMID:25050540

  12. Axon diameters and conduction velocities in the macaque pyramidal tract

    PubMed Central

    Firmin, L.; Field, P.; Maier, M. A.; Kraskov, A.; Kirkwood, P. A.; Nakajima, K.; Lemon, R. N.

    2014-01-01

    Small axons far outnumber larger fibers in the corticospinal tract, but the function of these small axons remains poorly understood. This is because they are difficult to identify, and therefore their physiology remains obscure. To assess the extent of the mismatch between anatomic and physiological measures, we compared conduction time and velocity in a large number of macaque corticospinal neurons with the distribution of axon diameters at the level of the medullary pyramid, using both light and electron microscopy. At the electron microscopic level, a total of 4,172 axons were sampled from 2 adult male macaque monkeys. We confirmed that there were virtually no unmyelinated fibers in the pyramidal tract. About 14% of pyramidal tract axons had a diameter smaller than 0.50 μm (including myelin sheath), most of these remaining undetected using light microscopy, and 52% were smaller than 1 μm. In the electrophysiological study, we determined the distribution of antidromic latencies of pyramidal tract neurons, recorded in primary motor cortex, ventral premotor cortex, and supplementary motor area and identified by pyramidal tract stimulation (799 pyramidal tract neurons, 7 adult awake macaques) or orthodromically from corticospinal axons recorded at the mid-cervical spinal level (192 axons, 5 adult anesthetized macaques). The distribution of antidromic and orthodromic latencies of corticospinal neurons was strongly biased toward those with large, fast-conducting axons. Axons smaller than 3 μm and with a conduction velocity below 18 m/s were grossly underrepresented in our electrophysiological recordings, and those below 1 μm (6 m/s) were probably not represented at all. The identity, location, and function of the majority of corticospinal neurons with small, slowly conducting axons remains unknown. PMID:24872533

  13. Association between abdominal aortic diameter and peripheral vascular disease.

    PubMed

    Rajkumar, C; Bonapace, S; Starr, J; Radia, M; Bulpitt, C J

    1997-09-01

    Fifty-four elderly people 81.2 years +/- 7.4 (mean age +/- s.d., range 66-98 years) were selected. These included 20 men (78.6 +/- 6.4 years, range 70-91 years) and 34 women (82.2 +/- 7.6 years, range 66-98 years). The relationship between the size of the abdominal aorta and various cardiovascular risk indicators such as calf:-brachial systolic pressure ratio, plasma cholesterol, triglycerides, and random blood glucose were examined. Abdominal aortic diameter correlated well with calf:-brachial systolic ratio measured by Doppler method over the posterior tibial artery and taking the lowest result of the right and left side (r = -0.28, P = 0.04). This correlation tended to be stronger in men (r = -0.55, P = 0.02) compared to women (r = -0.10, P = 0.57). However, the relationship tended to be confined to the systolic pressure in the left leg, raising the hypothesis that left-sided vascular disease is better related to aortic diameter, possibly due to a difference in the effects of reflected waves between the two sides. This needs further investigation. The contrast between the sexes was seen in the absence of any significant difference in resting blood pressure and calf:brachial systolic pressure ratio between the two. This finding suggests that the sex differences in the relationship between the size of the abdominal aorta and calf:brachial systolic pressure ratio are related to intrinsic properties of the arterial wall. PMID:9364278

  14. ZnTeO{sub 3} crystal growth by a modified Bridgman technique

    SciTech Connect

    Nawash, Jalal M. Lynn, Kelvin G.

    2014-12-15

    Highlights: • ZnTeO{sub 3} single crystals were grown for the first time by a modified Bridgman method. • The growth is still possible in a system that lacks congruent melting. • A growth is best when melt is exposed to a steeper axial thermal gradient. • Optical and electrical properties were investigated for the grown crystals. - Abstract: Zinc Tellurite (ZnTeO{sub 3}) crystals were grown for the first time using a modified Bridgman method with a 2.5 kHz radio frequency (RF) furnace. Single crystal growth of ZnTeO{sub 3} was hindered by many complicating factors, such as the evaporation of TeO{sub 2} above 700 °C and the formation of more than one phase during crystal growth. While there were several successful runs that produced ZnTeO{sub 3} single crystals, it was found that large (≥10 cm{sup 3}) single ZnTeO{sub 3} crystals resulted when the crucible was exposed to a steeper vertical thermal gradient and when the temperature of the melt was raised to at least 860 °C. The results of powder X-ray diffraction (XRD) patterns were in accordance with the X-ray powder diffraction file (PDF) for ZnTeO{sub 3}. Some optical, electrical and structural properties of ZnTeO{sub 3} single crystals were reported in this paper.

  15. Biological Macromolecule Crystallization Database

    National Institute of Standards and Technology Data Gateway

    SRD 21 Biological Macromolecule Crystallization Database (Web, free access)   The Biological Macromolecule Crystallization Database and NASA Archive for Protein Crystal Growth Data (BMCD) contains the conditions reported for the crystallization of proteins and nucleic acids used in X-ray structure determinations and archives the results of microgravity macromolecule crystallization studies.

  16. Growth of <001> TGCC crystals by Sankaranarayanan-Ramasamy (SR) method and its characterization

    NASA Astrophysics Data System (ADS)

    Boopathi, K.; Ramasamy, P.

    2015-06-01

    Single crystals of tris (glycine) Calcium (II) dichloride (TGCC) were successfully grown by Sankaranarayanan-Ramasamy (SR) method and conventional slow evaporation solution technique which have the sizes of 40 mm in length, 20 mm in diameter and 10×10×3 mm3 respectively. The grown TGCC crystals have been subjected to single crystal X-ray diffraction, UV-Vis NIR studies, Vickers micro hardness analysis, laser damage and SHG analysis. The transmittance of the grown crystal was analyzed by recording UV-Vis-NIR analysis. Mechanical strength of the SR method grown crystals was higher than the conventional method grown crystal.

  17. Growth of <001> TGCC crystals by Sankaranarayanan–Ramasamy (SR) method and its characterization

    SciTech Connect

    Boopathi, K.; Ramasamy, P.

    2015-06-24

    Single crystals of tris (glycine) Calcium (II) dichloride (TGCC) were successfully grown by Sankaranarayanan-Ramasamy (SR) method and conventional slow evaporation solution technique which have the sizes of 40 mm in length, 20 mm in diameter and 10×10×3 mm{sup 3} respectively. The grown TGCC crystals have been subjected to single crystal X-ray diffraction, UV-Vis NIR studies, Vickers micro hardness analysis, laser damage and SHG analysis. The transmittance of the grown crystal was analyzed by recording UV-Vis-NIR analysis. Mechanical strength of the SR method grown crystals was higher than the conventional method grown crystal.

  18. Rapid Crystallization of the Bishop Magma

    NASA Astrophysics Data System (ADS)

    Gualda, G. A.; Anderson, A. T.; Sutton, S. R.

    2007-12-01

    Substantial effort has been made to understand the longevity of rhyolitic magmas, and particular attention has been paid to the systems in the Long Valley area (California). Recent geochronological data suggest discrete magma bodies that existed for hundreds of thousands of years. Zircon crystallization ages for the Bishop Tuff span 100-200 ka, and were interpreted to reflect slow crystallization of a liquid-rich magma. Here we use the diffusional relaxation of Ti zoning in quartz to investigate the longevity of the Bishop magma. We have used such an approach to show the short timescales of crystallization of Ti-rich rims on quartz from early- erupted Bishop Tuff. We have now recognized Ti-rich cores in quartz that can be used to derive the timescales of their crystallization. We studied four samples of the early-erupted Bishop. Hand-picked crystals were mounted on glass slides and polished. Cathodoluminescence (CL) images were obtained using the electron microprobe at the University of Chicago. Ti zoning was documented using the GeoSoilEnviroCARS x-ray microprobe at the Advanced Photon Source (Argonne National Lab). Quartz crystals in all 4 samples include up to 3 Ti-bearing zones: a central core (50-100 μm in diameter, ca. 50 ppm Ti), a volumetrically predominant interior (~40 ppm Ti), and in some crystals a 50-100 μm thick rim (50 ppm Ti). Maximum estimates of core residence times were calculated using a 1D diffusion model, as the time needed to smooth an infinitely steep profile to fit the observed profile. Surprisingly, even for the largest crystals studied - ca. 2 mm in diameter - core residence times are less than 1 ka. Calculated growth rates imply that even cm-sized crystals crystallized in less than 10 ka. Crystal size distribution data show that crystals larger than 3 mm are exceedingly rare, such that the important inference is that the bulk of the crystallization of the early-erupted Bishop magma occurred in only a few thousand years. This timescale

  19. Investigation of early growth of calcium hydroxide crystals in cement solution by soft x-ray transmission microscopy

    SciTech Connect

    Harutyunyan, V. S.; Kirchheim, A. P.; Monteiro, P. J. M.; Aivazyan, A. P.; Fischer, P.

    2009-02-02

    Research on cement hydration was performed at the full-field soft transmission X-ray microscope XM-1 located at beamline 6.1.2 at the Advanced Light Source (ALS) in Berkeley CA which is operated by the Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California. A series of works [1-3] has been conducted using this microscope for the in situ observation and qualitative analysis of through-solution hydration products and products of topochemical reactions, which form in cementitious aqueous solutions. This paper studies the precipitation of the calcium hydroxide (CH) crystals from the cement solution. The analysis of successive images of the hydration process provides critical quantitative information about the growth rate of calcium hydroxide (CH) crystals, the supersaturation ratio, and the kinetic and diffusion coefficients of the growth process. ASTM Type II portland cement and 6% C{sub 4}A{sub 3}{bar S} admixture were mixed in aqueous solution and saturated with respect to CH and gypsum. The C{sub 4}A{sub 3}{bar S} admixture was included in the experimental program because of the general research program on expansive cements, and adding C{sub 4}A{sub 3}{bar S} to portland cement is an efficient method of generating ettringite and significant early-age expansion. The solution/solid materials ratio was 10 cm{sup 3}/g, which is higher than the one existing in regular concrete and mortars; to compensate for this dilution, the solution was originally saturated with CH and gypsum. To allow sufficient transmission of the soft X-rays, a small droplet was taken from the supernatant solution and assembled in the sample holder, and then squeezed between two silicon nitride windows for the analysis. The X-ray optical setup of the microscope XM-1 is described elsewhere [2]. In this experiment, a wavelength of 2.4 nm (516.6 eV) was used. The radiation transmitting the sample was detected using an X-ray CCD camera, with a resolution of 35 nm provided

  20. Photonic crystal microcavity lasers and laser arrays

    NASA Astrophysics Data System (ADS)

    Cao, Jiang-Rong

    As a state-of-the-art technology, photonic crystal microcavity lasers have great potentials to resolve many semiconductor laser performance challenges, owing to their compact size, high spontaneous emission factor, and inherent advantages in dimension scalability. This thesis describes efficient numerical analyzing methods for multimode photonic crystal microcavities, including a parallel computing three-dimensional finite-difference time-domain method combined with Pade interpolation, point group projection, and vectorial Green's function method. With the help of these analyzing tools, various experimental photonic crystal microcavity devices fabricated in InGaAsP/InP based materials were studies. Room temperature optical pumped InGaAsP suspended membrane photonic crystal microcavity lasers were demonstrated. Their lithographical fine-tuning, above room temperature operations, mode identifications and polarizations were demonstrated. Room temperature continuous wave (CW) optically pumped photonic crystal microcavity lasers at diameter less than 3.2 mum were demonstrated with crystalline alpha-Al 2O3 (sapphire) as a cladding layer to the InGaAsP membrane. The far-field radiation profiles from these microcavity lasers were measured and compared with our numerical modeling predictions. Two electrical injection scenes for photonic crystal microcavity lasers were introduced, together with some preliminary results including the demonstrations of optically pumped lasing of highly doped cavities and cavities with an electrical conduction post underneath. Electrically excited photonic crystal microcavity light emitting diodes (LEDs) were also experimentally demonstrated.

  1. Correlation of the ratio of caudal vena cava diameter and aorta diameter with systolic pressure variation in anesthetized dogs.

    PubMed

    Meneghini, Caterina; Rabozzi, Roberto; Franci, Paolo

    2016-02-01

    OBJECTIVE To evaluate the correlation coefficient of the ratio between diameter of the caudal vena cava (CVC) and diameter of the aorta (Ao) in dogs as determined ultrasonographically with systolic pressure variation (SPV). ANIMALS 14 client-owned dogs (9 females and 5 males; mean ± SD age, 73 ± 40 months; mean body weight, 22 ± 7 kg) that underwent anesthesia for repair of skin wounds. PROCEDURES Anesthesia was induced. Controlled mechanical ventilation with a peak inspiratory pressure of 8 cm H2O was immediately started, and SPV was measured. During a brief period of suspension of ventilation, CVC-to-Ao ratio was measured on a transverse right-lateral intercostal ultrasonographic image obtained at the level of the porta hepatis. When the SPV was ≥ 4 mm Hg, at least 1 bolus (3 to 4 mL/kg) of Hartmann solution was administered IV during a 1-minute period. Bolus administration was stopped and the CVC-to-Ao ratio measured when SPV was < 4 mm Hg. Correlation coefficient analysis was performed. RESULTS 28 measurements were obtained. The correlation coefficient was 0.86 (95% confidence interval, 0.72 to 0.93). Mean ± SD SPV and CVC-to-Ao ratio before bolus administration were 7 ± 2 mm Hg and 0.52 ± 0.16, respectively. Mean ± SD SPV and CVC-to-Ao ratio after bolus administration were 2 ± 0.6 mm Hg and 0.91 ± 0.13, respectively. CONCLUSIONS AND CLINICAL RELEVANCE In this study, the CVC-to-Ao ratio was a feasible, noninvasive ultrasonographically determined value that correlated well with SPV. (Am J Vet Res 2016;77:137-143). PMID:27027706

  2. Crystallization process

    DOEpatents

    Adler, Robert J.; Brown, William R.; Auyang, Lun; Liu, Yin-Chang; Cook, W. Jeffrey

    1986-01-01

    An improved crystallization process is disclosed for separating a crystallizable material and an excluded material which is at least partially excluded from the solid phase of the crystallizable material obtained upon freezing a liquid phase of the materials. The solid phase is more dense than the liquid phase, and it is separated therefrom by relative movement with the formation of a packed bed of solid phase. The packed bed is continuously formed adjacent its lower end and passed from the liquid phase into a countercurrent flow of backwash liquid. The packed bed extends through the level of the backwash liquid to provide a drained bed of solid phase adjacent its upper end which is melted by a condensing vapor.

  3. Ribbon Crystals

    PubMed Central

    Bohr, Jakob; Markvorsen, Steen

    2013-01-01

    A repetitive crystal-like pattern is spontaneously formed upon the twisting of straight ribbons. The pattern is akin to a tessellation with isosceles triangles, and it can easily be demonstrated with ribbons cut from an overhead transparency. We give a general description of developable ribbons using a ruled procedure where ribbons are uniquely described by two generating functions. This construction defines a differentiable frame, the ribbon frame, which does not have singular points, whereby we avoid the shortcomings of the Frenet–Serret frame. The observed spontaneous pattern is modeled using planar triangles and cylindrical arcs, and the ribbon structure is shown to arise from a maximization of the end-to-end length of the ribbon, i.e. from an optimal use of ribbon length. The phenomenon is discussed in the perspectives of incompatible intrinsic geometries and of the emergence of long-range order. PMID:24098360

  4. Classification of precipitation types using fall velocity-diameter relationships from 2D-video distrometer measurements

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Jung, Sung-Hwa; Park, Hong-Mok; Kwon, Soohyun; Lin, Pay-Liam; Lee, GyuWon

    2015-09-01

    Fall velocity-diameter relationships for four different snowflake types (dendrite, plate, needle, and graupel) were investigated in northeastern South Korea, and a new algorithm for classifying hydrometeors is proposed for distrometric measurements based on the new relationships. Falling ice crystals (approximately 40 000 particles) were measured with a two-dimensional video disdrometer (2DVD) during a winter experiment from 15 January to 9 April 2010. The fall velocity-diameter relationships were derived for the four types of snowflakes based on manual classification by experts using snow photos and 2DVD measurements: the coefficients (exponents) for different snowflake types were 0.82 (0.24) for dendrite, 0.74 (0.35) for plate, 1.03 (0.71) for needle, and 1.30 (0.94) for graupel, respectively. These new relationships established in the present study (PS) were compared with those from two previous studies. Hydrometeor types were classified with the derived fall velocity-diameter relationships, and the classification algorithm was evaluated using 3× 3 contingency tables for one rain-snow transition event and three snowfall events. The algorithm showed good performance for the transition event: the critical success indices (CSIs) were 0.89, 0.61 and 0.71 for snow, wet-snow and rain, respectively. For snow events, the algorithm performance for dendrite and plate (CSIs = 1.0 and 1.0, respectively) was better than for needle and graupel (CSIs = 0.67 and 0.50, respectively).

  5. Four-plate piezoelectric actuator driving a large-diameter special optical fiber for nonlinear optical microendoscopy.

    PubMed

    Wang, Ying; Li, Zhi; Liang, Xiaobao; Fu, Ling

    2016-08-22

    In nonlinear optical microendoscope (NOME), a fiber with excellent optical characteristics and a miniature scanning mechanism at the distal end are two key components. Double-clad fibers (DCFs) and double-clad photonic crystal fibers (DCPCFs) have shown great optical characteristics but limited vibration amplitude due to large diameter. Besides reducing the damping of fiber cantilever, optimizing the structural of the actuator for lower energy dissipation also contributes to better driving capability. This paper presented an optimized actuator for driving a particular fiber cantilever in the view point of energy. Firstly, deformation energy of a bending fiber cantilever operating in resonant mode is investigated. Secondly, strain and stress analyses revealed that the four-plate actuator achieved lower energy dissipation. Then, finite-element simulations showed that the large-diameter fiber yielded an adequate vibration amplitude driven by a four-plate actuator, which was confirmed by experiments of our home-made four-plate actuator prototypes. Additionally, a NOME based on a DCPCF with a diameter of 350 μm driven by four-plate piezoelectric actuator has been developed. The NOME can excite and collect intrinsic second-harmonic and two-photon fluorescence signals with the excitation power of 10-30 mW and an adequate field of view of 200 μm, which suggest great potential applications in neuroscience and clinical diagnoses. PMID:27557270

  6. Microbes make average 2 nanometer diameter crystalline UO2 particles.

    NASA Astrophysics Data System (ADS)

    Suzuki, Y.; Kelly, S. D.; Kemner, K. M.; Banfield, J. F.

    2001-12-01

    It is well known that phylogenetically diverse groups of microorganisms are capable of catalyzing the reduction of highly soluble U(VI) to highly insoluble U(IV), which rapidly precipitates as uraninite (UO2). Because biological uraninite is highly insoluble, microbial uranyl reduction is being intensively studied as the basis for a cost-effective in-situ bioremediation strategy. Previous studies have described UO2 biomineralization products as amorphous or poorly crystalline. The objective of this study is to characterize the nanocrystalline uraninite in detail in order to determine the particle size, crystallinity, and size-related structural characteristics, and to examine the implications of these for reoxidation and transport. In this study, we obtained U-contaminated sediment and water from an inactive U mine and incubated them anaerobically with nutrients to stimulate reductive precipitation of UO2 by indigenous anaerobic bacteria, mainly Gram-positive spore-forming Desulfosporosinus and Clostridium spp. as revealed by RNA-based phylogenetic analysis. Desulfosporosinus sp. was isolated from the sediment and UO2 was precipitated by this isolate from a simple solution that contains only U and electron donors. We characterized UO2 formed in both of the experiments by high resolution-TEM (HRTEM) and X-ray absorption fine structure analysis (XAFS). The results from HRTEM showed that both the pure and the mixed cultures of microorganisms precipitated around 1.5 - 3 nm crystalline UO2 particles. Some particles as small as around 1 nm could be imaged. Rare particles around 10 nm in diameter were also present. Particles adhere to cells and form colloidal aggregates with low fractal dimension. In some cases, coarsening by oriented attachment on \\{111\\} is evident. Our preliminary results from XAFS for the incubated U-contaminated sample also indicated an average diameter of UO2 of 2 nm. In nanoparticles, the U-U distance obtained by XAFS was 0.373 nm, 0.012 nm

  7. Modular Small Diameter Vascular Grafts with Bioactive Functionalities

    PubMed Central

    Neufurth, Meik; Wang, Xiaohong; Tolba, Emad; Dorweiler, Bernhard; Schröder, Heinz C.; Link, Thorben; Diehl-Seifert, Bärbel; Müller, Werner E. G.

    2015-01-01

    We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca2+ through formation of Ca2+ bridges between the polyanions, alginate, N,O-CMC, and polyP (alginate-Ca2+-N,O-CMC-polyP). The bTEBV are formed by pressing the hydrogel through an extruder into a hardening solution, containing Ca2+. In this universal scaffold of the bTEBV biomaterial, polycations such as poly(l-Lys), poly(d-Lys) or a His/Gly-tagged RGD peptide (three RGD units) were incorporated, which promote the adhesion of endothelial cells to the vessel surface. The mechanical properties of the biopolymer material (alginate-Ca2+-N,O-CMC-polyP-silica) revealed a hardness (elastic modulus) of 475 kPa even after a short incubation period in CaCl2 solution. The material of the artificial vascular grafts (bTEBVs with an outer size 6 mm and 1.8 mm, and an inner diameter 4 mm and 0.8 mm, respectively) turned out to be durable in 4-week pulsatile flow experiments at an alternating pressure between 25 and 100 mbar (18.7 and 75.0 mm Hg). The burst pressure of the larger (smaller) vessels was 850 mbar (145 mbar). Incorporation of polycationic poly(l-Lys), poly(d-Lys), and especially the His/Gly-tagged RGD peptide, markedly increased the adhesion of human, umbilical vein/vascular endothelial cells, EA.HY926 cells, to the surface of the hydrogel. No significant effect of the polyP samples on the clotting of human plasma is measured. We propose that the metabolically degradable

  8. Earth Climate Changes Connected To Solar Diameter and Irradiance Variabilities

    NASA Astrophysics Data System (ADS)

    Lefebvre, S.; Rozelot, J. P.

    Recent studies indicate that small but persistent variations in the total solar irradiance may play an important role in climate changes. If it is known that such changes are mainly due to changes in sunspots darkness and faculae brightness, it begins to be understood that changes in the radius of the Sun may also play a role. In a first part of this paper, we will show how the irradiance is affected by small distortions of the solar shape. Indeed such departures to a pure spherical Sun can be modelized as they reflect the gravitational distortions inside the Sun (variability of the rotation rate both in latitude and in depth as deduced by helioseismic measurements). These departures have been also observed from space (MDI on board SOHO) and from ground (solar astrolabes, scanning heliometer or other means). Such a variability on the Sun's di- ameter, certainly of no more than 40 mas (maybe less), will imply a change in the luminosity of about 6 parts per 10000. For the time being such variations have not been yet taken into account in the Earth climate changes. In the second part of this paper, we will focus on a longer period of time. We will briefly review the variabil- ity of the solar diameter over the last past four centuries, as it is suspected now with a rather good confidence that such a temporal variability may have a sense. We will compare this variability with the global Earth temperatures used as a climatic proxy. It can be seen that diameter changes over such a long period of time are indicative of an external variability on the Earth climate. The physical mechanism involved is obviously through the irradiance changes for which we will emphasize the need to get accurate and simultaneous measurements of the Sun's radius. The determination of the commonly used ratio W, which measures the relative variations of the radius over the relative variations of the irradiance, and as deduced in the first part of this paper, is helpful to pinpoint the source of

  9. Attached cavitation at a small diameter ultrasonic horn tip

    NASA Astrophysics Data System (ADS)

    Žnidarčič, Anton; Mettin, Robert; Cairós, Carlos; Dular, Matevž

    2014-02-01

    Ultrasonic horn transducers are frequently used in applications of acoustic cavitation in liquids, for instance, for cell disruption or sonochemical reactions. They are operated typically in the frequency range up to about 50 kHz and have tip diameters from some mm to several cm. It has been observed that if the horn tip is sufficiently small and driven at high amplitude, cavitation is very strong, and the tip can be covered entirely by the gas/vapor phase for longer time intervals. A peculiar dynamics of the attached cavity can emerge with expansion and collapse at a self-generated frequency in the subharmonic range, i.e., below the acoustic driving frequency. Here, we present a systematic study of the cavitation dynamics in water at a 20 kHz horn tip of 3 mm diameter. The system was investigated by high-speed imaging with simultaneous recording of the acoustic emissions. Measurements were performed under variation of acoustic power, air saturation, viscosity, surface tension, and temperature of the liquid. Our findings show that the liquid properties play no significant role in the dynamics of the attached cavitation at the small ultrasonic horn. Also the variation of the experimental geometry, within a certain range, did not change the dynamics. We believe that the main two reasons for the peculiar dynamics of cavitation on a small ultrasonic horn are the higher energy density on a small tip and the inability of the big tip to "wash" away the gaseous bubbles. Calculation of the somewhat adapted Strouhal number revealed that, similar to the hydrodynamic cavitation, values which are relatively low characterize slow cavitation structure dynamics. In cases where the cavitation follows the driving frequency this value lies much higher - probably at Str > 20. In the spirit to distinguish the observed phenomenon with other cavitation dynamics at ultrasonic transducer surfaces, we suggest to term the observed phenomenon of attached cavities partly covering the full horn

  10. Crystallization of the Zagami Shergottite: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Lofgren, Gary E.; McCoy, Timothy J.

    2000-01-01

    Spherulites are usually rounded or spherical objects found in rhyolitic obsidian. They usually comprise acicular crystals of alkali feldspar that radiate from a single point. The radiating array of crystalline fibers typically have a similar crystallographic orientation such that a branch fiber departs slightly but appreciably from that of its parent fiber. Individual fibers range from 1 to several micrometers in diameter. The spherulites most likely form by heterogeneous nucleation on microscopic seed crystals, bubbles, or some other surface at high degrees of supercooling. They grow very rapidly stabilizing their fibrous habit and typically range in size from microscopic to a few cm in diameter.

  11. Liquid Crystal Devices.

    ERIC Educational Resources Information Center

    Bradshaw, Madeline J.

    1983-01-01

    The nature of liquid crystals and several important liquid crystal devices are described. Ideas for practical experiments to illustrate the properties of liquid crystals and their operation in devices are also described. (Author/JN)

  12. Liquid Crystal Inquiries.

    ERIC Educational Resources Information Center

    Marroum, Renata-Maria

    1996-01-01

    Discusses the properties and classification of liquid crystals. Presents a simple experiment that illustrates the structure of liquid crystals and the differences between the various phases liquid crystals can assume. (JRH)

  13. The Submarine 4-km diameter Corossol Crater, Eastern Canada: Evidence for an impact origin

    NASA Astrophysics Data System (ADS)

    Higgins, Michael D.; Lajeunesse, Patrick; St-Onge, Guillaume; Locat, Jacques; Sanfacon, Richard; Duchesne, Mathieu J.

    2014-05-01

    The newly-discovered Corossol Crater lies in the northwestern Gulf of St. Lawrence (Eastern Canada; 50°3'N, 66°23'W) and was found in 40-185 metres of water using high-resolution multibeam sonar. It is a 4 km in diameter complex circular structure with a central uplift and concentric rings. Glacial resurfacing indicates that it predates the last phase of glaciation in this area. Dredging on the central uplift recovered many angular clasts of hard grey limestone, which forms the bedrock in much of this area. One 4 cm clast of limestone breccia is somewhat different from the other blocks and has characteristics that suggest that it is an impact breccia. The block comprises fragments of calcite limestone up to 2 mm long. In many parts of the block these fragments have thin black rims. At the edges of the block these rims are brown, presumably reflecting aqueous alteration. Mineral grains in the rims are too small to characterize, but the fact that the ensemble can be oxidized suggests that it contains sulfides. In places the block is cut by veins of fine-grained calcite with euhedral dolomite crystals. The most unusual component is rare droplets up to 2 mm long, commonly fragmented. The droplets comprise a glassy matrix with a composition very close to fluorapatite and opaque crystals that have a composition close to pyrite. A few droplets have up to 5% vesicles. Fluorapatite requires fusion temperatures of about 1600 C, which cannot be achieved at the surface of the Earth by endogenous processes. A single fragmented quartz crystal with planar features was found close to one droplet. Universal stage measurements of the orientation of the planar features give an angle of 42 degrees which is close to that of {10-13} planes. This is the most common set of deformation planes produced during shock metamorphism of quartz. Unfortunately no other grains were found with similar planes. The glassy droplets and shocked quartz together suggest that the clast was produced by an

  14. Curvature-directed crystallization of polymer dielectrics in nanopores

    NASA Astrophysics Data System (ADS)

    Reid, Dariya; Ehlinger, Bridget; Shao, Lin; Lutkenhaus, Jodie

    2014-03-01

    When a polymer is constricted in geometries smaller than its unperturbed molecular size its properties may greatly differ from the bulk state. The effect of cylindrical confinement on crystallization of isotactic polypropylene (iPP) and polycarbonate (PC) was studied. Polymer nanowires were prepared by melt-wetting into nanoporous templates of varying diameter (15 - 200 nm). X-ray diffraction (XRD) studies reveal that iPP crystallizes into the α-phase and preferentially orients along the long axis of the pore. Using differential scanning calorimetry (DSC) it is shown that iPP transitions from hetero to homogeneous nucleation as the pore diameter decreases. The isothermal crystallization kinetics is analyzed using Avrami analysis and a progression, with time, into primarily 1D crystallization is presented.

  15. Economic strategies of plant absorptive roots vary with root diameter

    NASA Astrophysics Data System (ADS)

    Kong, D. L.; Wang, J. J.; Kardol, P.; Wu, H. F.; Zeng, H.; Deng, X. B.; Deng, Y.

    2016-01-01

    Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

  16. High reliability bond program using small diameter aluminum wire

    NASA Technical Reports Server (NTRS)

    Macha, M.; Thiel, R. A.

    1975-01-01

    The program was undertaken to characterize the performance of small diameter aluminum wire ultrasonically bonded to conductors commonly encountered in hybrid assemblies, and to recommend guidelines for improving this performance. Wire, 25.4, 38.1 and 50.8 um (1, 1.5 and 2 mil), was used with bonding metallization consisting of thick film gold, thin film gold and aluminum as well as conventional aluminum pads on semiconductor chips. The chief tool for evaluating the performance was the double bond pull test in conjunction with a 72 hour - 150 C heat soak and -65 C to +150 C thermal cycling. In practice the thermal cycling was found to have relatively little effect compared to the heat soak. Pull strength will decrease after heat soak as a result of annealing of the aluminum wire; when bonded to thick film gold, the pull strength decreased by about 50% (weakening of the bond interface was the major cause of the reduction). Bonds to thin film gold lost about 30 - 40% of their initial pull strenth; weakening of the wire itself at the bond heel was the predominant cause. Bonds to aluminum substrate metallization lost only about 22%. Bonds between thick and thin film gold substrate metallization and semiconductor chips substantiated the previous conclusions but also showed that in about 20 to 25% of the cases, bond interface failure occurred at the semiconductor chip.

  17. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Smith, Earnest C. (Inventor); Oliver, Charles E. (Inventor); Redmon, John W., Sr. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1987-01-01

    A tool is shown having a cross beam assembly made of beams joined by a center box structure. The assembly is adapted to be mounted by brackets to the outer end of a cylindrical case. The center box structure has a vertical shaft rotatably mounted therein and extending beneath the assembly. Secured to the vertical shaft is a radius arm which is adapted to rotate with the shaft. On the longer end of the radius arm is a measuring tip which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm. An electric servomotor rotates the vertical shaft and an electronic resolver provides an electric signal representing the angle of rotation of the shaft. The electric signals are provided to a computer station which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  18. Aggregate Morphology Evolution by Sintering: Number & Diameter of Primary Particles

    PubMed Central

    Eggersdorfer, Max L.; Kadau, Dirk; Herrmann, Hans J.; Pratsinis, Sotiris E.

    2013-01-01

    The structure of fractal-like agglomerates (physically-bonded) and aggregates (chemically- or sinter-bonded) is important in aerosol synthesis of nanoparticles, and in monitoring combustion emissions and atmospheric particles. It influences also particle mobility, scattering, and eventually performance of nanocomposites, suspensions and devices made with such particles. Here, aggregate sintering by viscous flow of amorphous materials (silica, polymers) and grain boundary diffusion of crystalline ceramics (titania, alumina) or metals (Ni, Fe, Ag etc.) is investigated. A scaling law is found between average aggregate projected area and equivalent number of constituent primary particles during sintering: from fractal-like agglomerates to aggregates and eventually compact particles (e.g. spheres). This is essentially a relation independent of time, material properties and sintering mechanisms. It is used to estimate the equivalent primary particle diameter and number in aggregates. The evolution of aggregate morphology or structure is quantified by the effective fractal dimension (Df) and mass-mobility exponent (Dfm) and the corresponding prefactors. The Dfm increases monotonically during sintering converging to 3 for a compact particle. Therefore Dfm and its prefactor could be used to gauge the degree or extent of sintering of agglomerates made by a known collision mechanism. This analysis is exemplified by comparison to experiments of silver nanoparticle aggregates sintered at different temperatures in an electric tube furnace. PMID:23658467

  19. Continuous Measurement of Particle Hygroscopicity as a Function of Diameter

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Anderson, B. E.; Ziemba, L. D.; Thornhill, K. L.; Moore, R.; Beyersdorf, A. J.; Winstead, E. L.; Crumeyrolle, S.; Wagner, N.; Langridge, J. M.; Richardson, M.; Lack, D. A.; Law, D. C.; Shingler, T.; Sorooshian, A.

    2012-12-01

    An ultra-high sensitivity aerosol spectrometer (UHSAS, Droplet Measurement Technologies, Boulder, CO, USA) has been substantially modified to humidify the aerosol sample stream. The size distribution of deliquesced particles at humidities as high as 95% is measured. By combining a Mie model of instrument response with measurements of dry and wet size distributions, the hygroscopic growth factor as a function of particle diameter can be estimated. By operating a second, well-calibrated dry UHSAS simultaneously with the humidified UHSAS, the size-dependent particle hygroscopicity can be determined continuously, which is particularly useful for airborne sampling where rapid time response is required. The technique has been applied to laboratory particles of inorganic salts and of polystyrene latex, and to mixed sulfate/organic particles and dense forest fire smoke measured on an aircraft during the Deep Convective Clouds and Chemistry (DC3) project. Results will be compared with measurements of aerosol extinction at different RH values and of hygroscopic growth made with a differential aerosol sizing and hygroscopicity spectrometer probe (DASH-SP). Initial evaluations of changes in hygroscopicity due to processing in convective clouds will be presented. Limitations of the technique, such as the effects of external mixtures and insoluble components, will be discussed.

  20. Development of the 15 meter diameter hoop column antenna

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The building of a deployable 15-meter engineering model of the 100 meter antenna based on the point-design of an earlier task of this contract, complete with an RF-capable surface is described. The 15 meter diameter was selected so that the model could be tested in existing manufacturing, near-field RF, thermal vacuum, and structural dynamics facilities. The antenna was designed with four offset paraboloidal reflector surfaces with a focal length of 366.85 in and a primary surface accuracy goal of .069 in rms. Surface adjustment capability was provided by manually resetting the length of 96 surface control cords which emanated from the lower column extremity. A detailed description of the 15-meter Hoop/Column Antenna, major subassemblies, and a history of its fabrication, assembly, deployment testing, and verification measurements are given. The deviation for one aperture surface (except the outboard extremity) was measured after adjustments in follow-on tests at the Martin Marietta Near-field Facility to be .061 in; thus the primary surface goal was achieved.

  1. Cylindrical surface profile and diameter measuring tool and method

    NASA Technical Reports Server (NTRS)

    Currie, James R. (Inventor); Kissel, Ralph R. (Inventor); Oliver, Charles E. (Inventor); Smith, Earnest C. (Inventor); Redmon, John W. (Inventor); Wallace, Charles C. (Inventor); Swanson, Charles P. (Inventor)

    1989-01-01

    A tool is shown having a cross beam assembly (15) made of beams (18, 19, 20, 21) joined by a center box structure (23). The assembly (15) is adapted to be mounted by brackets (16) to the outer end of a cylindrical case (11). The center box structure (23) has a vertical shaft (25) rotatably mounted therein and extending beneath the assembly (15). Secured to the vertical shaft (25) is a radius arm (28) which is adapted to rotate with shaft (25). On the longer end of the radius arm (28) is a measuring tip (30) which contacts the cylindrical surface to be measured and which provides an electric signal representing the radius of the cylindrical surface from the center of rotation of the radius arm (28). An electric servomotor (49) rotates the vertical shaft (25) and an electronic resolver (61) provides an electric signal representing the angle of rotation of the shaft (25). The electric signals are provided to a computer station (73) which has software for its computer to calculate and print out the continuous circumference profile of the cylindrical surface, and give its true diameter and the deviations from the ideal circle.

  2. Sustainable yields from large diameter wells in shallow weathered aquifers

    NASA Astrophysics Data System (ADS)

    Rushton, K. R.; de Silva, C. S.

    2016-08-01

    Large diameter wells in shallow weathered aquifers provide a valuable source of water for domestic and agricultural purposes in many locations including the Indian subcontinent. However, when used for irrigation, these wells often fail towards the end of the dry season. By considering two case studies in the dry and intermediate rainfall zones of Sri Lanka, reasons for the limited yield of these wells are identified. The first case study is concerned with a sloping catchment; a significant proportion of the precipitation during the rainy season either becomes runoff or passes down-gradient through the aquifer and is discharged at the ground surface. Furthermore, during the dry season, groundwater discharge continues. In the second case study the topography is generally flat but, even though the aquifer fills most years during the rainy season, there is often only sufficient water to irrigate about half of each farmer's holding. These investigations are based on field information and the development of conceptual and computational models. Of critical importance in assessing the long term yield of a well is the formation of a seepage face on the side of the well, with the water table a significant distance above the pumping water level. Consequently the water table may only be lowered to about half the depth of the well. The paper concludes with recommendations for the exploitation of groundwater from shallow weathered aquifers to minimise the risk of failure during the dry season.

  3. Minimizing the Diameter of a Network Using Shortcut Edges

    NASA Astrophysics Data System (ADS)

    Demaine, Erik D.; Zadimoghaddam, Morteza

    We study the problem of minimizing the diameter of a graph by adding k shortcut edges, for speeding up communication in an existing network design. We develop constant-factor approximation algorithms for different variations of this problem. We also show how to improve the approximation ratios using resource augmentation to allow more than k shortcut edges. We observe a close relation between the single-source version of the problem, where we want to minimize the largest distance from a given source vertex, and the well-known k-median problem. First we show that our constant-factor approximation algorithms for the general case solve the single-source problem within a constant factor. Then, using a linear-programming formulation for the single-source version, we find a (1 + ɛ)-approximation using O(klogn) shortcut edges. To show the tightness of our result, we prove that any ({3 over 2}-ɛ)-approximation for the single-source version must use Ω(klogn) shortcut edges assuming P ≠ NP.

  4. Internal Diameter HVAF Spraying for Wear and Corrosion Applications

    NASA Astrophysics Data System (ADS)

    Lyphout, C.; Björklund, S.

    2015-01-01

    Electrolytic hard chrome (EHC) methods are still widely utilized in the printing, automotive and off-shore industries. Alternative methods to EHC have been widely developed in the past decade by conventional HVOF processes and more recently HVAF systems, which are processing at higher kinetic energy and more particularly at lower temperature, significantly increasing wear and corrosion resistance properties. A dedicated internal diameter HVAF system is here presented, and coatings characteristics are compared to the one obtained by standard HVAF coatings. Specially R&D designed fixtures with inside bore of 200 mm have been manufactured for this purpose, with a possibility to spray samples at increasing depth up to 400 mm while simulating closed bottom bore spraying. WC-based and Cr3C2-based powder feedstock materials have been deposited onto high-strength steel substrates. Respective coating microstructures, thermally induced stresses and corrosion resistance are discussed for further optimization of coating performances. The fact that the ID-HVAF system is utilized both for spraying and gritblasting procedures is also given a particular interest.

  5. Characterization of an 8-cm Diameter Ion Source System

    NASA Technical Reports Server (NTRS)

    Li, Zhongmin; Hawk, C. W.; Hawk, Clark W.; Buttweiler, Mark S.; Williams, John D.; Buchholtz, Brett

    2005-01-01

    Results of tests characterizing an 8-cm diameter ion source are presented. The tests were conducted in three separate vacuum test facilities at the University of Alabama-Huntsville, Colorado State University, and L3 Communications' ETI division. Standard ion optics tests describing electron backstreaming and total-voltage-limited impingement current behavior as a function of beam current were used as guidelines for selecting operating conditions where more detailed ion beam measurements were performed. The ion beam was profiled using an in-vacuum actuating probe system to determine the total ion current density and the ion charge state distribution variation across the face of the ion source. Both current density and ExB probes were utilized. The ion current density data were used to obtain integrated beam current, beam flatness parameters, and general beam profile shapes. The ExB probe data were used to determine the ratio of doubly to singly charged ion current. The ion beam profile tests were performed at over six different operating points that spanned the expected operating range of the DAWN thrusters being developed at L3. The characterization tests described herein reveal that the 8-cm ion source is suitable for use in (a) validating plasma diagnostic equipment, (b) xenon ion sputtering and etching studies of spacecraft materials, (c) plasma physics research, and (d) the study of ion thruster optics at varying conditions.

  6. Dimer adsorption on a (100) nanotube of arbitrary diameter, with first- and second-neighbor interactions.

    PubMed

    Phares, Alain J; Grumbine, David W

    2014-06-17

    Dimer adsorption on an infinitely long (100) or square lattice nanotube of fixed lattice constant and arbitrary number M of sites in its normal cross section is considered with first- and second-neighbor interaction energies, V and W, respectively. An increase in M keeping the lattice constant fixed corresponds to a nanotube with increasing diameter. The system is at thermodynamic equilibrium and relatively low temperature in order to determine all of the possible crystallization patterns or phases that may exist. Under these conditions, the energy phase space diagram is two-dimensional, and the dimensionless parameters are u = W/|V| and v = μ/|V|, where μ is the sum of the chemical potential energy, μ', of a dimer and the dimer-substrate interaction energy V0. The low temperature energy phase diagram is numerically generated using a transfer matrix method adapted to the present problem. For both attractive and repulsive first-neighbors, it is M-independent for M even, and its M-dependence when M is odd is established. As a consistency check, the infinite odd-M limit matches exactly the M-independent phase diagram for even M. The knowledge of the boundaries of the regions in the phase diagram where these phases occur and the knowledge of their respective occupational configurations are particularly useful information when experimental data on dimer adsorption on square nanotubes become available. PMID:24897920

  7. YPEL4 modulates HAC15 adrenal cell proliferation and is associated with tumor diameter.

    PubMed

    Oki, Kenji; Plonczynski, Maria W; Gomez-Sanchez, Elise P; Gomez-Sanchez, Celso E

    2016-10-15

    Yippee-like (YPEL) proteins are thought to be related to cell proliferation because of their structure and location in the cell. The aim of this study was to clarify the effects of YPEL4 on aldosterone production and cell proliferation in the human adrenocortical cell line (HAC15) and aldosterone producing adenoma (APA). Basal aldosterone levels in HAC15 cells over-expressing YPEL4 was higher than those of control HAC15 cells. The positive effects of YPEL4 on cell proliferation were detected by XTT assay and crystal violet staining. YPEL4 levels in 39 human APA were 2.4-fold higher compared to those in 12 non-functional adrenocortical adenomas, and there was a positive relationship between YPEL4 levels and APA diameter (r = 0.316, P < 0.05). In summary, we have demonstrated that YPEL4 stimulates human adrenal cortical cell proliferation, increasing aldosterone production as a consequence. These results in human adrenocortical cells are consistent with the clinical observations with APA in humans. PMID:27333825

  8. Gelled colloidal crystals as tunable optical filters for spectrophotometers

    NASA Astrophysics Data System (ADS)

    Sugao, Yukihiro; Onda, Sachiko; Toyotama, Akiko; Takiguchi, Yoshihiro; Sawada, Tsutomu; Hara, Shigeo; Nishikawa, Suguru; Yamanaka, Junpei

    2016-08-01

    We examined the performance of charged colloidal crystals immobilized in a polymer gel as tunable optical filters. The colloidal crystals of charged silica particles (particle diameter = 121 nm; particle concentration = 3.5 vol %; and Bragg wavelength λB = 630–720 nm) were produced by unidirectional crystallization under a temperature gradient. Photocurable gelation reagents were dissolved in the sample beforehand; this enabled gel immobilization of the crystals under ultraviolet illumination. The crystals had dimensions of more than 25 mm2 in area and 1 mm in thickness, and spatial λB variations of less than 1%. Upon mechanical compression, λB values shifted linearly and reversibly over almost the entire visible spectrum. Using the gelled crystals as tunable optical filters, we measured the transmittance spectra of various samples and found them to be in close agreement with those determined using a spectrophotometer equipped with optical gratings.

  9. Dislocation distribution in large high-purity germanium crystal

    NASA Astrophysics Data System (ADS)

    Mei, Hao; Wang, Guojian; Mei, Dongming; Huang, Mianliang; Yang, Gang; Guan, Yutong; Cubed Collaboration

    2014-03-01

    We investigated the impacts of growth rate, time-temperature profile, thermal gradient on the dislocation distribution in large high-purity germanium crystal (12 cm in diameter) grown via Czochralski along <100>orientation. The time-temperature profiles of the crystal grown at different input power were investigated using direct measurements and computational modeling. The effect of crystallization speed on dislocation density is discussed from the context of thermal gradient during growth. Several samples from the grown crystals were used for this investigation. We measured dislocation density across the entire cross-section of the grown crystal through the microscope. By measuring and calculating the dislocation density, we were able to identify the denseness and the type of dislocation, which allows us to study how the thermal stress impacts the dislocation generation and distribution across the large grown crystals. This work is supported by DOE grant DE-FG02-10ER46709 and the state of South Dakota.

  10. Prediction of binary hard-sphere crystal structures.

    PubMed

    Filion, Laura; Dijkstra, Marjolein

    2009-04-01

    We present a method based on a combination of a genetic algorithm and Monte Carlo simulations to predict close-packed crystal structures in hard-core systems. We employ this method to predict the binary crystal structures in a mixture of large and small hard spheres with various stoichiometries and diameter ratios between 0.4 and 0.84. In addition to known binary hard-sphere crystal structures similar to NaCl and AlB2, we predict additional crystal structures with the symmetry of CrB, gammaCuTi, alphaIrV, HgBr2, AuTe2, Ag2Se, and various structures for which an atomic analog was not found. In order to determine the crystal structures at infinite pressures, we calculate the maximum packing density as a function of size ratio for the crystal structures predicted by our GA using a simulated annealing approach. PMID:19518387

  11. Using Inorganic Crystals To Grow Protein Crystals

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.; Mcpherson, Alexander A.

    1989-01-01

    Solid materials serve as nucleating agents. Protein crystals induced by heterogeneous nucleation and in some cases by epitaxy to grow at lower supersaturations than needed for spontaneous nucleation. Heterogeneous nucleation makes possible to grow large, defect-free single crystals of protein more readily. Such protein crystals benefits research in biochemistry and pharmacology.

  12. Diameter Control and Photoluminescence of ZnO Nanorods from Trialkylamines

    DOE PAGESBeta

    Andelman, Tamar; Gong, Yinyan; Neumark, Gertrude; O'Brien, Stephen

    2007-01-01

    A novel solution method to control the diameter of ZnO nanorods is reported. Small diameter (2-3 nm) nanorods were synthesized from trihexylamine, and large diameter (50–80 nm) nanorods were synthesized by increasing the alkyl chain length to tridodecylamine. The defect (green) emission of the photoluminescence (PL) spectra of the nanorods varies with diameter, and can thus be controlled by the diameter control. The small ZnO nanorods have strong green emission, while the large diameter nanorods exhibit a remarkably suppressed green band. We show that this observation supports surface oxygen vacancies as the defect that gives rise to the green emission.

  13. Saqqar: A 34 km diameter impact structure in Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Kenkmann, Thomas; Afifi, Abdulkader M.; Stewart, Simon A.; Poelchau, Michael H.; Cook, Douglas J.; Neville, Allen S.

    2015-11-01

    Here we present the first proof of an impact origin for the Saqqar circular structure in northwestern Saudi Arabia (Neville et al. ), with an apparent diameter of 34 km, centered at 29°35'N, 38°42'E. The structure is formed in Cambrian-Devonian siliciclastics and is unconformably overlain by undeformed Cretaceous and Paleogene sediments. The age of impact is not well constrained and lies somewhere between 410 and 70 Ma. The subsurface structure is constrained by 2-D reflection seismic profiles and six drilled wells. First-order structural features are a central uplift that rises approximately 2 km above regional datums, surrounded by a ring syncline. The crater rim is defined by circumferential normal faults. The central uplift and ring syncline correspond to a Bouguer gravity high and an annular ring-like low, respectively. The wells were drilled within the central uplift, the deepest among them exceed 2 km depth. Sandstone core samples from these wells show abundant indicators of a shock metamorphic overprint. Planar deformation features (PDFs) were measured with orientations along (0001), {101¯3}, and less frequently along {101¯1} and {101¯4}. Planar fractures (PFs) predominantly occur along (0001) and {101¯1}, and are locally associated with feather features (FFs). In addition, some shocked feldspar grains and strongly deformed mica flakes were found. The recorded shock pressure ranges between 5 and 15 GPa. The preserved level of shock and the absence of an allochthonous crater fill suggest that Saqqar was eroded by 1-2 km between the Devonian and Maastrichtian. The documentation of unequivocal shock features proves the formation of the Saqqar structure by a hypervelocity impact event.

  14. Quality control on crimping of large diameter welding pipe

    NASA Astrophysics Data System (ADS)

    Fan, Lifeng; Gao, Ying; Li, Qiang; Xu, Hongshen

    2012-11-01

    Crimping is used in production of large diameter submerged-arc welding pipes. Many researches are focused on crimping in certain manufacturing mode of welding pipe. The application scopes of research achievements become limited due to lack of uniformity in theoretical analysis. In order to propose a crimping prediction method in order to control forming quality, the theory model of crimping based on elastic-plastic mechanics is established. The main technical parameters are determined by theoretical analysis, including length of crimping, base radius of punch, terminal angle of punch, base radius of die, terminal angle of die and horizontal distance between punch and die. In addition, a method used to evaluate the forming quality is presented, which investigates the bending angle after springback, forming force, straight edge length and equivalent radius of curvature. In order to investigate the effects of technical parameters on forming quality, a two-dimensional finite element model is established by finite element software ABAQUS. The finite element model is verified in that its shapes error is less than 5% by comparable experiments, which shows that their geometric precision meets demand. The crimping characteristics is obtained, such as the distribution of stress and strain and the changes of forming force, and the relation curves of technical parameters on forming quality are given by simulation analysis. The sensitivity analysis indicates that the effects of length of crimping, technical parameters of punch on forming quality are significant. In particular, the data from simulation analysis are regressed by response surface method (RSM) to establish prediction model. The feasible technical parameters are obtained from the prediction model. This method presented provides a new thought used to design technical parameters of crimping forming and makes a basis for improving crimping forming quality.

  15. AUTOMATED WATER LEVEL MEASUREMENTS IN SMALL-DIAMETER AQUIFER TUBES

    SciTech Connect

    PETERSEN SW; EDRINGTON RS; MAHOOD RO; VANMIDDLESWORTH PE

    2011-01-14

    Groundwater contaminated with hexavalent chromium, strontium-90, and uranium discharges into the Columbia River along approximately 16 km (10 mi) of the shoreline. Various treatment systems have and will continue to be implemented to eliminate the impact of Hanford Site contamination to the river. To optimize the various remediation strategies, it is important to understand interactions between groundwater and the surface water of the Columbia River. An automated system to record water levels in aquifer sampling tubes installed in the hyporheic zone was designed and tested to (1) gain a more complete understanding of groundwater/river water interactions based on gaining and losing conditions ofthe Columbia River, (2) record and interpret data for consistent and defensible groundwater/surface water conceptual models that may be used to better predict subsurface contaminant fate and transport, and (3) evaluate the hydrodynamic influence of extraction wells in an expanded pump-and-treat system to optimize the treatment system. A system to measure water levels in small-diameter aquifer tubes was designed and tested in the laboratory and field. The system was configured to allow manual measurements to periodically calibrate the instrument and to permit aquifer tube sampling without removing the transducer tube. Manual measurements were collected with an e-tape designed and fabricated especially for this test. Results indicate that the transducer system accurately records groundwater levels in aquifer tubes. These data are being used to refine the conceptual and numeric models to better understand interactions in the hyporheic zone of the Columbia River and the adjacent river water and groundwater, and changes in hydrochemistry relative to groundwater flux as river water recharges the aquifer and then drains back out in response to changes in the river level.

  16. Solar Diameter Measurements from Eclipses as a Solar Variability Proxy

    NASA Astrophysics Data System (ADS)

    Waring Dunham, David; Sofia, Sabatino; Guhl, Konrad; Herald, David Russell

    2015-08-01

    Since thermal relaxation times for the Sun are thousands of years, small variations of the Solar intensity are proportional to small variations of the Solar diameter on decadal time scales. In a combination between observations and theory, reliable values of the relation constant W are known, that allow transformation of historical variations of radius into variations of the solar luminosity. During the past 45 years, members of the International Occultation Timing Association (IOTA) have observed 20 annular and total solar eclipses from locations near the path edges. Baily’s beads, whose occurrence and duration are considerably prolonged as seen from path edge locations, were first timed visually, mostly using projection techniques, but since about 1980, they have been timed mainly from analysis of video recordings. The edge locations have the advantage that most of the beads are defined by the same features in the lunar polar regions that cause the phenomena at each eclipse. Some of the best-observed modern eclipses can be used to assess the accuracy of the results, which are limited mainly by the intensity drop at the Sun’s edge, and the consequent uncertainty in defining the edge. In addition, direct visual contact timings made near the path edges during earlier eclipses, back to 1715, have been found in the literature, and analyzed. Although the observations seem to show small variations, they are only a little larger than the assessed accuracies. The results can be improved with a consistent re-analysis of the observations using the much more accurate lunar profile data that is now available from the Japanese Kaguya and NASA’s LRO lunar orbiter observations. Also, IOTA has plans to observe future eclipses with a variety of techniques that were used in the past, to better assess the accuracies of the different observational methods that have been used, and determine any systematic differences between them.

  17. The crystal nucleation theory revisited: The case of 2D colloidal crystals

    NASA Astrophysics Data System (ADS)

    González, A. E.; Ixtlilco-Cortés, L.

    2011-03-01

    Most of the theories and studies of crystallization and crystal nucleation consider the boundaries between the crystallites and the fluid as smooth. The crystallites are the small clusters of atoms, molecules and/or particles with the symmetry of the crystal lattice that, with a slight chance of success, would grow to form the crystal grains. In fact, in the classical nucleation theory, the crystallites are assumed to have a spherical shape (circular in 2D). As far are we are aware, there is only one experimental work [1] on colloidal crystals that founds rough surfaces for the crystallites and for the crystal grains. Motivated by this work, we performed large Kinetic Monte Carlo simulations in 2D, that would follow the eventual growing of a few crystallites to form the crystal grains. The used potential has, besides the impenetrable hard core, a soft core followed by a potential well. We found that indeed the crystallites have a fractal boundary, whose value we were able to obtain. See the figure below of a typical isolated crystallite. We were also able to obtain the critical crystallite size, measured by its number of particles, Nc, and not by any critical radius. The boundaries of the crystals above Nc also have a fractal structure but of a lower value, closer to one. Finally, we also obtained the line tension between the crystallites and the surrounding fluid, as function of temperature and particle diameter, as well as the chemical potential difference between these two phases. In the URL: www.fis.unam.mx˜˜agus˜ there are posted two movies that can be downloaded: (1) 2D_crystal_nucleation.mp4, and (2) 2D_crystal_growth.mp4, that illustrate the crystal nucleation and its further growth.

  18. Shape-controlled crystal growth of Sr3NbGa3Si2O14 and Sr3TaGa3Si2O14 piezoelectric crystals by the micro-pulling-down method.

    PubMed

    Yokota, Yuui; Sato, Masato; Futami, Yoshisuke; Tota, Kazushige; Onodera, Ko; Yanagida, Takayuki; Yoshikawa, Akira

    2012-09-01

    We grew column-shaped Sr(3)NbGa(3)Si(2)O(14) (SNGS) and Sr(3)TaGa(3)Si(2)O(14) (STGS) langasite-type piezoelectric single crystals by the micro-pulling-down (μ-PD) method. 3-mm-diameter SNGS and STGS crystals were grown using a Pt-Rh crucible with a 3-mm-diameter columnar die. According to X-ray rocking curve measurements, the grown crystals had crystallinity equivalent to that of crystals grown by the Czochralski (Cz) method. The crystals were single-phase materials with langasite-type crystal structure. The lattice parameters of the grown crystals were almost consistent with those of crystals grown by the Cz method. PMID:23007751

  19. Skyrmion-Based Dynamic Magnonic Crystal.

    PubMed

    Ma, Fusheng; Zhou, Yan; Braun, H B; Lew, W S

    2015-06-10

    A linear array of periodically spaced and individually controllable skyrmions is introduced as a magnonic crystal. It is numerically demonstrated that skyrmion nucleation and annihilation can be accurately controlled by a nanosecond spin polarized current pulse through a nanocontact. Arranged in a periodic array, such nanocontacts allow the creation of a skyrmion lattice that causes a periodic modulation of the waveguide's magnetization, which can be dynamically controlled by changing either the strength of an applied external magnetic field or the density of the injected spin current through the nanocontacts. The skyrmion diameter is highly dependent on both the applied field and the injected current. This implies tunability of the lowest band gap as the skyrmion diameter directly affects the strength of the pinning potential. The calculated magnonic spectra thus exhibit tunable allowed frequency bands and forbidden frequency bandgaps analogous to that of conventional magnonic crystals where, in contrast, the periodicity is structurally induced and static. In the dynamic magnetic crystal studied here, it is possible to dynamically turn on and off the artificial periodic structure, which allows switching between full rejection and full transmission of spin waves in the waveguide. These findings should stimulate further research activities on multiple functionalities offered by magnonic crystals based on periodic skyrmion lattices. PMID:25989181

  20. Bulk Crystal Growth of Nonlinear Optical Organic Materials Using Inverted Vertical Gradient Freeze Method

    NASA Technical Reports Server (NTRS)

    Choi, J.; Cruz, Magda; Metzl, R.; Wang, W. S.; Aggarwal, M. D.; Penn, Benjamin G.; Frazier, Donald O.

    1998-01-01

    A new process for producing large bulk single crystals of benzil (C6H5COCOC6H5) is reported in this paper. Good quality crystals have been successfully grown using this approach to crystal growth. This method seems to be very promising for other thermally stable NLO organic materials also. The entire contents vycor crucible 1.5 inch in diameter and 2 inch deep was converted to single crystal. Purity of the starting growth material is also an important factor in the final quality of the grown crystals. The entire crystal can be very easily taken out of the crucible by simple maneuvering. Initial characterization of the grown crystals indicated that the crystals are as good as other crystals grown by conventional Bridgman Stockbarger technique.

  1. Stem diameter variations as a versatile research tool in ecophysiology.

    PubMed

    De Swaef, Tom; De Schepper, Veerle; Vandegehuchte, Maurits W; Steppe, Kathy

    2015-10-01

    High-resolution stem diameter variations (SDV) are widely recognized as a useful drought stress indicator and have therefore been used in many irrigation scheduling studies. More recently, SDV have been used in combination with other plant measurements and biophysical modelling to study fundamental mechanisms underlying whole-plant functioning and growth. The present review aims to scrutinize the important insights emerging from these more recent SDV applications to identify trends in ongoing fundamental research. The main mechanism underlying SDV is variation in water content in stem tissues, originating from reversible shrinkage and swelling of dead and living tissues, and irreversible growth. The contribution of different stem tissues to the overall SDV signal is currently under debate and shows variation with species and plant age, but can be investigated by combining SDV with state-of-the-art technology like magnetic resonance imaging. Various physiological mechanisms, such as water and carbon transport, and mechanical properties influence the SDV pattern, making it an extensive source of information on dynamic plant behaviour. To unravel these dynamics and to extract information on plant physiology or plant biophysics from SDV, mechanistic modelling has proved to be valuable. Biophysical models integrate different mechanisms underlying SDV, and help us to explain the resulting SDV signal. Using an elementary modelling approach, we demonstrate the application of SDV as a tool to examine plant water relations, plant hydraulics, plant carbon relations, plant nutrition, freezing effects, plant phenology and dendroclimatology. In the ever-expanding SDV knowledge base we identified two principal research tracks. First, in detailed short-term experiments, SDV measurements are combined with other plant measurements and modelling to discover patterns in phloem turgor, phloem osmotic concentrations, root pressure and plant endogenous control. Second, long-term SDV time

  2. Mixed crystal organic scintillators

    DOEpatents

    Zaitseva, Natalia P; Carman, M Leslie; Glenn, Andrew M; Hamel, Sebastien; Hatarik, Robert; Payne, Stephen A; Stoeffl, Wolfgang

    2014-09-16

    A mixed organic crystal according to one embodiment includes a single mixed crystal having two compounds with different bandgap energies, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source, wherein the signal response signature does not include a significantly-delayed luminescence characteristic of neutrons interacting with the organic crystal relative to a luminescence characteristic of gamma rays interacting with the organic crystal. According to one embodiment, an organic crystal includes bibenzyl and stilbene or a stilbene derivative, the organic crystal having a physical property of exhibiting a signal response signature for neutrons from a radioactive source.

  3. Liquid encapsulated crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1989-01-01

    Low-defect crystals are grown in a closed ampoule under a layer of encapsulant. After crystal growth, the crystal is separated from the melt and moved into the layer of encapsulant and cooled to a first temperature at which crystal growth stops. The crystal is then moved into the inert gas ambient in the ampoule and further cooled. The crystal can be separated from the melt by decanting the melt into an adjacent reservoir or by rotating the ampoule to rotate the crystal into the encapsulant layer.

  4. Liquid encapsulated crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1987-01-01

    Low-defect crystals are grown in a closed ampoule under a layer of encapsulant. After crystal growth, the crystal is separated from the melt and moved into the layer of encapsulant and cooled to a first temperature at which crystal growth stops. The crystal is then moved into the inert gas ambient in the ampoule and further cooled. The crystal can be separated from the melt by decanting the melt into and adjacent reservoir or by rotating the ampoule to rotate the crystal into the encapsulant layer.

  5. Effect of Diethylenetriamine and Triethylamine sensitization on the critical diameter of Nitromethane

    NASA Astrophysics Data System (ADS)

    Lee, J. J.; Jiang, J.; Choong, K. H.; Lee, J. H. S.

    2000-04-01

    In this work, the critical diameter for detonation was measured for Nitromethane (NM) sensitized with two different amines: Diethylenetriamine (DETA) and Triethylamine (TEA). The critical diameter in glass and polyvinylchloride tubes is found to decrease rapidly as the amount of sensitizer is increased, then increase past a critical amount of sensitizer. Thus the critical diameter reaches a minimum at a critical concentration of sensitizer. It was also found that the critical diameter is lower with DETA than with TEA.

  6. 77 FR 13284 - Small Diameter Graphite Electrodes From the People's Republic of China: Preliminary Results and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-06

    ... Antidumping Duty Administrative Review, 76 FR 67411 (November 1, 2011), and Small Diameter Graphite Electrodes... Final Determination, 74 FR at 2054, and Small Diameter Graphite Electrodes from the People's Republic of... International Trade Administration Small Diameter Graphite Electrodes From the People's Republic of...

  7. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  8. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  9. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  10. 15 CFR 241.4 - Application of tolerance for “diameter of head.”

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of head.â 241.4 Section 241.4 Commerce and Foreign Trade Regulations Relating to Commerce and Foreign... tolerance for “diameter of head.” (a) The tolerance established in this part for the dimension specified as “diameter of head” shall be applied to the diameter of the head over all, including the part which fits...

  11. Real-Time Structural and Electrical Characterization of Metal-Insulator Transition in Strain-Modulated Single-Phase VO2 Wires with Controlled Diameters.

    PubMed

    Kim, Min-Woo; Ha, Sung-Soo; Seo, Okkyun; Noh, Do Young; Kim, Bong-Joong

    2016-07-13

    Single-crystal VO2 wires have gained tremendous popularity for enabling the study of the fundamental properties of the metal-insulator transition (MIT); however, it remains tricky to precisely measure the intrinsic properties of the transitional phases with controlled wire-growth properties, such as diameter. Here, we report a facile method for growing VO2 wires with controlled diameters by separating the formation of the liquidus V2O5 seed droplets from the evolution of the VO2 wire using oxygen gas. The kinetic analyses suggest that the growth proceeds via the VS (vapor-solid) mechanism, whereas the droplet determines the size and the location of the wire. In situ Raman spectroscopy combined with analyses of the electrical properties of an individual wire allowed us to construct a diameter-temperature phase diagram from three initial phases (i.e., M1, T, and M2), which were created by misfit stress from the substrate and were preserved at room temperature. We also correlated this relation with resistivity-diameter and activation energy-diameter relations supported by theoretical modeling. These carefully designed approaches enabled us to elucidate the details of the phase transitions over a wide range of stress conditions, offering an opportunity to quantify relevant thermodynamic and electronic parameters (including resistivities, activation energies, and energy barriers of the key insulating phases) and to explain the intriguing behaviors of the T phase during the MIT. PMID:27253750

  12. Pressure cryocooling protein crystals

    DOEpatents

    Kim, Chae Un; Gruner, Sol M.

    2011-10-04

    Preparation of cryocooled protein crystal is provided by use of helium pressurizing and cryocooling to obtain cryocooled protein crystal allowing collection of high resolution data and by heavier noble gas (krypton or xenon) binding followed by helium pressurizing and cryocooling to obtain cryocooled protein crystal for collection of high resolution data and SAD phasing simultaneously. The helium pressurizing is carried out on crystal coated to prevent dehydration or on crystal grown in aqueous solution in a capillary.

  13. Manipulating light propagation and emission using photonic crystals

    SciTech Connect

    Nair, Rajesh V.; Jagatap, B. N.

    2014-03-31

    We discuss the synthesis and characterization of self-assembled photonic crystals using polymer colloids having sub-micron diameters. The angle resolved optical reflectivity measurements indicate the hybridization between stop gaps in the multiple Bragg diffraction regimes. Each diffraction resonances in the multiple Bragg diffraction regimes are assigned to respective crystal planes. We also discuss laser-induced studies of spontaneous emission in self-assembled photonic crystals having Rhodamine-B dye doped colloids. Our experimental results reveal more than 51% inhibition in emission intensity within the stop gap as compared to a proper reference sample.

  14. Effect of power arrangement on the crystal shape during the Kyropoulos sapphire crystal growth process

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Hung; Chen, Jyh-Chen; Lu, Chung-Wei; Liu, Che-Ming

    2012-08-01

    The Kyropoulos (KY) method is commonly used to grow large sized sapphire single crystals. The shape of the sapphire crystal thus grown is determined by the heater arrangement and the power reduction history in the Kyropoulos furnace. In order to grow high-quality sapphire single crystal, the heater arrangement should allow different power inputs in different sections in order to control the thermal field in the melt during the growth process. In this study, a numerical computation is performed to investigate the effects of the heater arrangement on the thermal and flow transport, the shape of the crystal-melt interface, and the power requirements during the Kyropoulos sapphire crystal growth process in a resistance heated furnace. Four different power ratio arrangements in a three-zone heater are considered. The results show that for the power arrangements considered herein, the temperature gradients along the crystallization front do not exceed 0.05 K/mm, and that, after the growth of the crown, the crystal maintains an almost constant diameter. The remelting phenomenon may occur during growth when the input power of the upper side of the heater is higher than that of the lower side of the heater.

  15. Theory of High Frequency Rectification by Silicon Crystals

    DOE R&D Accomplishments Database

    Bethe, H. A.

    1942-10-29

    The excellent performance of British "red dot" crystals is explained as due to the knife edge contact against a polished surface. High frequency rectification depends critically on the capacity of the rectifying boundary layer of the crystal, C. For high conversion efficiency, the product of this capacity and of the "forward" (bulk) resistance R {sub b} of the crystal must be small. For a knife edge, this product depends primarily on the breadth of the knife edge and very little upon its length. The contact can therefore have a rather large area which prevents burn-out. For a wavelength of 10 cm. the computations show that the breadth of the knife edge should be less than about 10 {sup -3} cm. For a point contact the radius must be less than 1.5 x 10 {sup -3} cm. and the resulting small area is conducive to burn-out. The effect of "tapping" is probably to reduce the area of contact. (auth)

  16. Radiation damage of BGO and CsI(Tl) crystals

    NASA Astrophysics Data System (ADS)

    Bieler, Ch.; Burkart, D.; Marks, J.; Riebesell, M.; Spitzer, H.; Wittenburg, K.; Winter, G.-G.

    1985-02-01

    We have measured the response of five 10-20 cm long BGO crystals from different manufacturers to irradiation with 137Cs γ-rays at doses of 40 and 85 rad. Immediately after irradiation the pulse height drops by 26-38% and recovers only partially with time. 110 d after irradiation the remaining damage is between 1 and 13%. A 10 cm long CsI (Tl) crystal shows pulse height reductions after irradiation which do not recover with time. The cumulative effect of a continuous irradiation on a BGO crystal (1 × 1× 15 cm 3) in a partially shielded position on the beam pipe of PETRA was measured over a period of 53 d. At an average daily dose of 1.9 rad the pulse height dropped continuously resulting in an overall pulse height loss of 9% in 7 weeks. This indicates that BGO when applied in long and narrow shapes is more sensitive to small radiation doses than previously assumed.

  17. Liquid crystals for organic thin-film transistors

    NASA Astrophysics Data System (ADS)

    Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-Ichi

    2015-04-01

    Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V-1 s-1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.

  18. Single crystal niobium tubes for particle colliders accelerator cavities

    SciTech Connect

    Murphy, James E

    2013-02-28

    The objective of this research project is to produce single crystal niobium (Nb) tubes for use as particle accelerator cavities for the Fermi laboratory’s International Linear Collider project. Single crystal Nb tubes may have superior performance compared to a polycrystalline tubes because the absence of grain boundaries may permit the use of higher accelerating voltages. In addition, Nb tubes that are subjected to the high temperature, high vacuum crystallization process are very pure and well annealed. Any impurity with a significantly higher vapor pressure than Nb should be decreased by the relatively long exposure at high temperature to the high vacuum environment. After application of the single crystal process, the surfaces of the Nb tubes are bright and shiny, and the tube resembles an electro polished Nb tube. For these reasons, there is interest in single crystal Nb tubes and in a process that will produce single crystal tubes. To convert a polycrystalline niobium tube into a single crystal, the tube is heated to within a few hundred °C of the melting temperature of niobium, which is 2477 °C. RF heating is used to rapidly heat the tube in a narrow zone and after reaching the operating temperature, the hot zone is slowly passed along the length of the tube. For crystallization tests with Nb tubes, the traverse rate was in the range of 1-10 cm per hour. All the crystallization tests in this study were performed in a water-cooled, stainless steel chamber under a vacuum of 5 x10-6 torr or better. In earliest tests of the single crystal growth process, the Nb tubes had an OD of 1.9 cm and a wall thickness of 0.15 mm. With these relatively small Nb tubes, the single crystal process was always successful in producing single crystal tubes. In these early tests, the operating temperature was normally maintained at 2200 °C, and the traverse rate was 5 cm per hour. In the next test series, the Nb tube size was increased to 3.8 cm OD and the wall thickness was

  19. Influence of the distribution of measuring points on the mean diameter determination of the Avogadro project's silicon spheres

    NASA Astrophysics Data System (ADS)

    Bartl, Guido; Nicolaus, Arnold

    2009-06-01

    The members of the International Avogadro Project are aiming at the redetermination of Avogadro's constant with a relative uncertainty of less than 2×10-8 in order to be qualified for the redefinition of the kilogram. Therefore, among other quantities, the volume of a sphere made of a silicon single crystal has to be determined very precisely with a diameter uncertainty of 0.3 nm. A special Fizeau interferometer with spherical reference faces has been developed at PTB providing the required precision in absolute interferometry and a generous coverage of the surface of the sphere at the same time. Due to the intrinsic imbalanced distribution of measurement positions given by the setup, an equalization has to be performed without introducing a numerical error. In this paper an appropriate procedure using point distributions on a sphere is described and characterized with regard to the number of points involved.

  20. Pseudomagnitudes and differential surface brightness: Application to the apparent diameter of stars

    NASA Astrophysics Data System (ADS)

    Chelli, Alain; Duvert, Gilles; Bourgès, Laurent; Mella, Guillaume; Lafrasse, Sylvain; Bonneau, Daniel; Chesneau, Olivier

    2016-05-01

    The diameter of a star is a major observable that serves to test the validity of stellar structure theories. It is also a difficult observable that is mostly obtained with indirect methods since the stars are so remote. Today only ~600 apparent star diameters have been measured by direct methods: optical interferometry and lunar occultations. Accurate star diameters are now required in the new field of exoplanet studies, since they condition the planets' sizes in transit observations, and recent publications illustrate a visible renewal of interest in this topic. Our analysis is based on the modeling of the relationship between measured angular diameters and photometries. It makes use of two new reddening-free concepts: a distance indicator called pseudomagnitude, and a quasi-experimental observable that is independent of distance and specific to each star, called the differential surface brightness (DSB). The use of all the published measurements of apparent diameters that have been collected so far, and a careful modeling of the DSB allow us to estimate star diameters with a median statistical error of 1.1%, knowing their spectral type and, in the present case, the VJHKs photometries. We introduce two catalogs, the JMMC Measured Diameters Catalog (JMDC), containing measured star diameters, and the second version of the JMMC Stellar Diameter Catalog (JSDC), augmented to about 453 000 star diameters. Finally, we provide simple formulas and a table of coefficients to quickly estimate stellar angular diameters and associated errors from (V, Ks) magnitudes and spectral types.

  1. Selective control of small versus large diameter axons using infrared laser light (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Lothet, Emilie H.; Shaw, Kendrick M.; Horn, Charles C.; Lu, Hui; Wang, Yves T.; Jansen, E. Duco; Chiel, Hillel J.; Jenkins, Michael W.

    2016-03-01

    Sensory information is conveyed to the central nervous system via small diameter unmyelinated fibers. In general, smaller diameter axons have slower conduction velocities. Selective control of such fibers could create new clinical treatments for chronic pain, nausea in response to chemo-therapeutic agents, or hypertension. Electrical stimulation can control axonal activity, but induced axonal current is proportional to cross-sectional area, so that large diameter fibers are affected first. Physiologically, however, synaptic inputs generally affect small diameter fibers before large diameter fibers (the size principle). A more physiological modality that first affected small diameter fibers could have fewer side effects (e.g., not recruiting motor axons). A novel mathematical analysis of the cable equation demonstrates that the minimum length along the axon for inducing block scales with the square root of axon diameter. This implies that the minimum length along an axon for inhibition will scale as the square root of axon diameter, so that lower radiant exposures of infrared light will selectively affect small diameter, slower conducting fibers before those of large diameter. This prediction was tested in identified neurons from the marine mollusk Aplysia californica. Radiant exposure to block a neuron with a slower conduction velocity (B43) was consistently lower than that needed to block a faster conduction velocity neuron (B3). Furthermore, in the vagus nerve of the musk shrew, lower radiant exposure blocked slow conducting fibers before blocking faster conducting fibers. Infrared light can selectively control smaller diameter fibers, suggesting many novel clinical treatments.

  2. Variation and Heritability in Hair Diameter and Curvature in an Australian Twin Sample.

    PubMed

    Ho, Yvonne Y W; Brims, Mark; McNevin, Dennis; Spector, Timothy D; Martin, Nicholas G; Medland, Sarah E

    2016-08-01

    Hair diameter and curvature are two characteristics of human scalp hair used in forensic contexts. While previous data show that subjective categorization of hair curvature is highly heritable, the heritability of objectively measured curvature and diameter, and variability of hair characteristics within each individual have not yet been studied. The present study measured hair diameter and curvature using an optical fiber diameter analyzer in a sample of 2,332 twins and siblings. Heritability was estimated using maximum likelihood structural equation modeling. Results show sex differences in the magnitude of genetic influence for mean diameter and curvature, with the vast majority of the variance accounted for by genetic effects in males (diameter = 86%, curvature = 53%) and females (diameter = 77%, curvature = 61%). The consistency of diameter (variance within an individual) was also highly heritable, but did not show sex limitation, with 68% of the variance accounted for by genetic factors. Moderate phenotypic correlations were seen between diameter and consistency (r = 0.3) but there was little correlation between diameter and curvature (r = -0.13). A bivariate Cholesky analysis was used to estimate the genetic and environmental correlations between hair diameter and consistency, yielding genetic correlations of r gF = 0.27 for females and r gM = 0.25 for males. PMID:27291867

  3. Direct Probes of 4 nm Diameter Gold Nanoparticles Interacting with Supported Lipid Bylayers

    SciTech Connect

    Troiano, Julianne; Olenick, Laura L.; Kuech, Thomas R.; Melby, Eric S.; Hu, Dehong; Lohse, Samuel E.; Mensch, Arielle C.; Dogangun, Merve; Vartanian, Arlane M.; Torelli, Marco; Ehimiaghe, Eseohi; Walter, Stephanie R.; Fu, Li; Anderton, Christopher R.; Zhu, Zihua; Wang, Hongfei; Orr, Galya; Murphy, Catherine; Hamers, Robert J.; Pedersen, Joel A.; Geiger, Franz M.

    2015-01-08

    Interfacial charge densities and potentials are determined for silica-supported phospholipid bilayers formed from lipids having zwitterionic, negatively charged, and positively charged headgroups. Quartz crystal microbalance with dissipation (QCM-D), fluorescence recovery after photobleaching (FRAP), and atomic force microscopy demonstrate the presence of well-formed supported lipid bilayers, which, as probed by vibrational sum frequency generation (SFG), undergo negligible structural changes along their alkyl chains when NaCl concentration is raised from 0.001 to 0.1 M. From second harmonic generation (SHG) measurements we estimate that each zwitterionic headgroup of the bilayer formed from pure DOPC is associated with an apparent charge of -0.028(+0.008/-0.007)×10-¹⁹C, corresponding to 1.8 ± 0.5 % of an elementary negative charge. Moreover, we show that a supported lipid bilayer carrying an apparent negative interfacial potential may interact with not just positively charged 4-nm diameter gold nanoparticles but also negatively charged gold nanoparticles. In this latter case, charge-charge repulsion does not appear to inhibit particle-bilayer interactions and is likely overcome by multivalent interactions that are estimated to involve 3-5 hydrogen-bond equivalents. FRAP, QCM-D, and SFG measurements indicate that the bilayers remain intact under the conditions of the experiments. SHG charge screening experiments are consistent with an apparent zero net charge density associated with the positively charged gold nanoparticles when they are attached to a supported lipid bilayer carrying an apparent negative potential. The results presented here serve to benchmark experimental and computational studies of the nano-bio interface.

  4. Twisted Single Crystals of Meta-Aromatic Polyamides

    NASA Astrophysics Data System (ADS)

    Lawrence, D. P.; Martin, D. C.

    1996-03-01

    The morphology of single crystals of the aromatic polyamide poly(metaphenylene isophthalamide) (MPDI or Nomex) was studied by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The single crystals of MPDI were slowly grown from 0.1 weight percent solution. MPDI forms elongated crystals which aggregate together to form highly regular twisted helical bundles. The repeat periods of the helices typically range from 240 nm to 1000 nm and the bundle diameters vary from 36 nm to 120 nm. The angle between the edge of the crystal and the bundle axis varies from 40 to 65 degrees. The regular twisting evidently arises from a bending moment induced by the triclinic symmetry of the MPDI unit cell and the lamellar geometry of the chain-folded single crystal.

  5. Crystal growth of organics for nonlinear optical applications

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Mazelsky, R.

    1993-01-01

    The crystal growth and characterization of organic and inorganic nonlinear optical materials were extensively studied. For example, inorganic crystals such as thallium arsenic selenide were studied in our laboratory for several years and crystals in sizes over 2.5 cm in diameter are available. Organic crystals are suitable for the ultraviolet and near infrared region, but are relatively less developed than their inorganic counterparts. Very high values of the second harmonic conversion efficiency and the electro-optic coefficient were reported for organic compounds. Single crystals of a binary organic alloy based on m.NA and CNA were grown and higher second harmonic conversion efficiency than the values reported for m.NA were observed.

  6. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  7. CRYSTAL COLLIMATION AT RHIC.

    SciTech Connect

    FLILLER,III, R.P.; DREES,A.; GASSNER,D.; HAMMONS,L.; MCINTYRE,G.; PEGGS,S.; TRBOJEVIC,D.; BIRYUKOV,V.; CHESNKOV,Y.; TEREKHOV,V.

    2002-06-02

    For the year 2001 run, a bent crystal was installed in the yellow ring of the Relativistic Heavy Ion Collider (RHIC). The crystal forms the first stage of a two stage collimation system. By aligning the crystal to the beam, halo particles are channeled through the crystal and deflected into a copper scraper. The purpose is to reduce beam halo with greater efficiency than with a scraper alone. In this paper we present the first results from the use of the crystal collimator. We compare the crystal performance under various conditions, such as different particle species, and beta functions.

  8. Synthesis of some calcium phosphate crystals using the useful biomass for immobilization of microorganisms

    NASA Astrophysics Data System (ADS)

    Kohiruimaki, T.

    2011-10-01

    Three sources of biomass generated by primary industry were used as the raw material for the synthesis of calcium phosphate crystals. Phosphoric acid was extracted from burned rice chaff using a 30% nitric acid solution, while scallop shells and gypsum of plasterboard were used as calcium sources. The calcium phosphate crystals were synthesized by a method involving homogeneous precipitation, and the relationship between the composition and shape of the crystals and the pH at the time of the precipitation was investigated. Monetite crystals in a petal form with a diameter ranging from 0.1 to 2 μm were precipitated at pH 2.0, while granular apatite crystals with a mean diameter of 1 μm were precipitated at pH 6.0. We also investigated the ability of the synthesized calcium phosphate crystals to immobilize lactic acid bacteria for practical use in industrial bioreactor. It was determined that monetite crystals with a diameter of 2 μm had the highest ability to fix lactic acid bacteria. The population of lactic acid bacteria was estimated to exceed 1,300 bacteria per crystal surface of 50 μm2 suggesting that these crystals may be of practical use in industrial fermenters.

  9. Growth and Physical Property Study of Single Nanowire (Diameter ~45 nm) of Half Doped Manganite

    DOE PAGESBeta

    Datta, Subarna; Chandra, Sayan; Samanta, Sudeshna; Das, K.; Srikanth, H.; Ghosh, Barnali

    2013-01-01

    We repormore » t here the growth and characterization of functional oxide nanowire of hole doped manganite of La 0.5 Sr 0.5 MnO 3 (LSMO). We also report four-probe electrical resistance measurement of a single nanowire of LSMO (diameter ~45 nm) using focused ion beam (FIB) fabricated electrodes. The wires are fabricated by hydrothermal method using autoclave at a temperature of 270 °C. The elemental analysis and physical property like electrical resistivity are studied at an individual nanowire level. The quantitative determination of Mn valency and elemental mapping of constituent elements are done by using Electron Energy Loss Spectroscopy (EELS) in the Transmission Electron Microscopy (TEM) mode. We address the important issue of whether as a result of size reduction the nanowires can retain the desired composition, structure, and physical properties. The nanowires used are found to have a ferromagnetic transition ( T C ) at around 325 K which is very close to the bulk value of around 330 K found in single crystal of the same composition. It is confirmed that the functional behavior is likely to be retained even after size reduction of the nanowires to a diameter of 45 nm. The electrical resistivity shows insulating behavior within the measured temperature range which is similar to the bulk system.« less

  10. Crystallization and saturation front propagation in silicic magma chambers

    NASA Astrophysics Data System (ADS)

    Lake, Ethan T.

    2013-12-01

    The cooling and crystallization style of silicic magma bodies in the upper crust falls on a continuum between whole-chamber processes of convection, crystal settling, and cumulate formation and interface-driven processes of conduction and crystallization front migration. In the end-member case of vigorous convection and crystal settling, volatile saturation advances downward from the roof and upward from the floor throughout the chamber. In the end-member case of stagnant magma bodies, volatile saturation occurs along an inward propagating front from all sides of the chamber. Ambient thermal gradient primarily controls the propagation rate; warm (⩾40 °C/km) geothermal gradients lead to thick (1200+ m) crystal mush zones and slow crystallization front propagation. Cold (<40 °C/km) geothermal gradients lead to rapid crystallization front propagation and thin (<1000 m) mush zones. Magma chamber geometry also exerts a first-order control on propagation rates; bodies with high surface to magma volume ratio and large Earth-surface-parallel faces exhibit more rapid propagation and thinner mush zones. Crystallization front propagation occurs at speeds of greater than 10 cm/yr (rhyolitic magma; 1 km thick sill geometry in a 20 °C/km geotherm), far faster than diffusion of volatiles in magma and faster than bubbles can nucleate, grow, and ascend through the chamber. Numerical simulations indicate saturation front propagation is determined primarily by pressure and magma crystallization rate; above certain initial water contents (4.4 wt.% in a dacite) the mobile magma is volatile-rich enough above 10 km depth to always contains a saturation front. Saturation fronts propagate down from the magma chamber roof at lower water contents (3.3 wt.% in a dacite at 5 km depth), creating an upper saturated interface for most common (4-6 wt.%) magma water contents. This upper interface promotes the production of a fluid pocket underneath the apex of the magma chamber. If the fluid

  11. Characterization of <0 1 0> directed KAP single crystals grown by Sankaranarayanan Ramasamy (SR) method

    NASA Astrophysics Data System (ADS)

    Senthil Pandian, M.; Balamurugan, N.; Bhagavannarayana, G.; Ramasamy, P.

    2008-08-01

    Single crystals of potassium acid phthalate (KAP), a semi-organic compound, have been grown at an average growth rate of 4 mm/day from aqueous solution by using the uniaxial crystal growth method of Sankaranarayanan-Ramasamy (SR). Transparent, cylindrical KAP crystal of size 70 mm length and 15 mm diameter was grown. The grown crystals were characterized by etching and UV-vis NIR analysis. HRXRD analysis indicates that the crystalline perfection of SR method-grown KAP is good. The KAP crystals grown by SR method have 9% higher transmittance than conventional method-grown crystal. The microhardness test was carried out on the (0 1 0) face and a load-dependent hardness was observed. TG-DTA evaluated the thermal properties of the grown crystal. KAP was found to be thermally stable up to 290 °C. The dielectric constant and dielectric loss of the crystal were studied as function of frequency and temperature.

  12. Use of anomolous thermal imaging effects for multi-mode systems control during crystal growth

    NASA Technical Reports Server (NTRS)

    Wargo, Michael J.

    1989-01-01

    Real time image processing techniques, combined with multitasking computational capabilities are used to establish thermal imaging as a multimode sensor for systems control during crystal growth. Whereas certain regions of the high temperature scene are presently unusable for quantitative determination of temperature, the anomalous information thus obtained is found to serve as a potentially low noise source of other important systems control output. Using this approach, the light emission/reflection characteristics of the crystal, meniscus and melt system are used to infer the crystal diameter and a linear regression algorithm is employed to determine the local diameter trend. This data is utilized as input for closed loop control of crystal shape. No performance penalty in thermal imaging speed is paid for this added functionality. Approach to secondary (diameter) sensor design and systems control structure is discussed. Preliminary experimental results are presented.

  13. YAP multi-crystal gamma camera prototype

    SciTech Connect

    Blazek, K.; Maly, P.; Notaristefani, F. de |; Pani, R.; Pellegrini, R.; Pergola, A.; Scopinaro, F.; Soluri, A.

    1995-10-01

    The Anger camera principle has shown a practical limit of a few millimeters spatial resolution. To overcome this limit, a new gamma camera prototype has been developed, based on a position-sensitive photomultiplier tue (PSPMT) coupled with a new scintillation crystal. The Hamamatsu R2486 PSPMT is a 76-mm diameter photomultiplier tube in which the electrons produced in the conventional bi-alkali photocathode are multiplied by proximity mesh dynodes and form a charge cloud around the original coordinates of the light photon striking the photocathode. A crossed wire anode array collects the charge and detects the original position. The intrinsic spatial resolution of PSPMT is better than 0.3 mm. The scintillation crystal consists of yttrium aluminum perovskit (YAP:Ce or YAlO{sub 3}:Ce). This crystal has a light efficient of about 38% relative to NaI, no hygroscopicity and a good gamma radiation absorption. To match the characteristics of the PSPMT, a special crystal assembly was produced by the Preciosa Company, consisting of a bundle of YAP:Ce pillars where single crystals have 0.6 {times} 0.6 mm{sup 2} cross section and 3 mm to 18 mm length. Preliminary results from such gamma camera prototypes show spatial resolution values ranging between 0.7 mm and 1 mm with an intrinsic detection efficiency of 37 {divided_by} 65% for 140 keV gamma energy.

  14. Substrate diameter and compliance affect the gripping strategies and locomotor mode of climbing boa constrictors.

    PubMed

    Byrnes, Greg; Jayne, Bruce C

    2010-12-15

    Arboreal habitats pose unique challenges for locomotion as a result of their narrow cylindrical surfaces and discontinuities between branches. Decreased diameter of branches increases compliance, which can pose additional challenges, including effects on stability and energy damping. However, the combined effects of substrate diameter and compliance are poorly understood for any animal. We quantified performance, kinematics and substrate deformation while boa constrictors (Boa constrictor) climbed vertical ropes with three diameters (3, 6 and 9 mm) and four tensions (0.5, 1.0, 1.5 and 2.0 body weights). Mean forward velocity decreased significantly with both decreased diameter and increased compliance. Both diameter and compliance had numerous effects on locomotor kinematics, but diameter had larger and more pervasive effects than compliance. Locomotion on the largest diameter had a larger forward excursion per cycle, and the locomotor mode and gripping strategy differed from that on the smaller diameters. On larger diameters, snakes primarily applied opposing forces at the same location on the rope to grip. By contrast, on smaller diameters forces were applied in opposite directions at different locations along the rope, resulting in increased rope deformation. Although energy is likely to be lost during deformation, snakes might use increased surface deformation as a strategy to enhance their ability to grip. PMID:21113006

  15. Electrochemical liquid-liquid-solid (ec-LLS) crystal growth: a low-temperature strategy for covalent semiconductor crystal growth.

    PubMed

    Fahrenkrug, Eli; Maldonado, Stephen

    2015-07-21

    details chosen for ec-LLS. Third, the rate of introduction of zero-valent materials into the liquid metal is precisely gated with a high degree of resolution by the applied potential/current. The intent of this Account is to summarize the key elements of ec-LLS identified to date, first contextualizing this method with respect to other semiconductor crystal growth methods and then highlighting some unique capabilities of ec-LLS. Specifically, we detail ec-LLS as a platform to prepare Ge and Si crystals from bulk- (∼1 cm(3)), micro- (∼10(-10) cm(3)), and nano-sized (∼10(-16) cm(3)) liquid metal electrodes in common solvents at low temperature. In addition, we describe our successes in the preparation of more compositionally complex binary covalent III-V semiconductors. PMID:26132141

  16. Apparatus for growing crystals

    NASA Technical Reports Server (NTRS)

    Jasinski, Thomas J. (Inventor); Witt, August F. (Inventor)

    1986-01-01

    An improved apparatus and method for growing crystals from a melt employing a heat pipe, consisting of one or more sections, each section serving to control temperature and thermal gradients in the crystal as it forms inside the pipe.

  17. Growth of dopamine crystals

    NASA Astrophysics Data System (ADS)

    Patil, Vidya; Patki, Mugdha

    2016-05-01

    Many nonlinear optical (NLO) crystals have been identified as potential candidates in optical and electro-optical devices. Use of NLO organic crystals is expected in photonic applications. Hence organic nonlinear optical materials have been intensely investigated due to their potentially high nonlinearities, and rapid response in electro-optic effect compared to inorganic NLO materials. There are many methods to grow organic crystals such as vapor growth method, melt growth method and solution growth method. Out of these methods, solution growth method is useful in providing constraint free crystal. Single crystals of Dopamine have been grown by evaporating the solvents from aqueous solution. Crystals obtained were of the size of orders of mm. The crystal structure of dopamine was determined using XRD technique. Images of crystals were obtained using FEG SEM Quanta Series under high vacuum and low KV.

  18. Crystallization from Gels

    NASA Astrophysics Data System (ADS)

    Narayana Kalkura, S.; Natarajan, Subramanian

    Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone

  19. Apparatus for mounting crystal

    DOEpatents

    Longeway, Paul A.

    1985-01-01

    A thickness monitor useful in deposition or etching reactor systems comprising a crystal-controlled oscillator in which the crystal is deposited or etched to change the frequency of the oscillator. The crystal rests within a thermally conductive metallic housing and arranged to be temperature controlled. Electrode contacts are made to the surface primarily by gravity force such that the crystal is substantially free of stress otherwise induced by high temperature.

  20. 78 FR 41369 - Certain Small Diameter Carbon and Alloy Seamless Standard, Line and Pressure Pipe From Romania...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ... on certain small diameter carbon and alloy seamless standard, line and pressure pipe (small diameter... diameter seamless pipe. The small diameter seamless pipe subject to the order is currently classifiable... small diameter seamless pipe from Romania entered, or withdrawn from warehouse, for......

  1. Convective flow effects on protein crystal growth

    NASA Technical Reports Server (NTRS)

    Rosenberger, Franz; Monaco, Lisa A.

    1994-01-01

    The long-term stability of the interferometric setup for the monitoring of protein morphologies has been improved. Growth or dissolution of a crystal on a 100 A scale can now be clearly distinguished from dimensional changes occurring within the optical path of the interferometer. This capability of simultaneously monitoring the local interfacial displacement at several widely-spaced positions on the crystal surface with high local depth resolution, has already yielded novel results. We found with lysozyme that (1) the normal growth rate is oscillatory, and (2) the mean growth step density is greater at the periphery of a facet than in its center. The repartitioning of Na(+) and Cl(-) ions between lysozyme solutions and crystals was studied for a wide range of crystallization conditions. A nucleation-growth-repartitioning model was developed to interpret the large body of data in a unified way. The results strongly suggests that (1) the ion to lysozyme ratio in the crystal depends mostly on kinetic rather than crystallographic parameters, and (2) lysozyme crystals possess a salt-rich core with a diameter on the order of 10 microns. The computational model for diffusive-convective transport in protein crystallization (see the First Report) has been applied to a realistic growth cell geometry, taking into account the findings of the above repartitioning studies. These results show that some elements of a moving boundary problem must be incorporated into the model in order to obtain a more realistic description. Our experimental setup for light scattering investigations of aggregation and nucleation in protein solutions has been extensively tested. Scattering intensity measurements with a true Rayleigh scatterer produced systematically increased forward scattering, indicating problems with glare. These have been resolved. Preliminary measurements with supersaturated lysozyme solutions revealed that the scatterers grow with time. Work has begun on a computer program

  2. Diameter and wall number control of carbon nanotubes by chemical vapor deposition

    SciTech Connect

    Xie, Rongsi; Zhong, Guofang Zhang, Can; Chen, Bingan; Santiago Esconjauregui, C.; Robertson, John

    2013-12-28

    We analyze the relationship between the average wall number (N) and the diameter (d) for carbon nanotubes (CNTs) grown by chemical vapour deposition. It is found that N depends linearly on d for diameters in the range of 2.5–10 nm, while single wall nanotubes predominate for diameters under about 2.1 nm. The linear relationship is found to depend somewhat on the growth conditions. It is also verified that the mean diameter depends on the diameter of the originating catalyst nanoparticle, and thus on the initial catalyst thickness where a thin film catalyst is used. This simplifies the characterisation of CNTs by electron microscopy. We also find a linear relationship between nanotube diameter and initial catalyst film thickness.

  3. Artistic Crystal Creations

    ERIC Educational Resources Information Center

    Lange, Catherine

    2008-01-01

    In this inquiry-based, integrative art and science activity, Grade 5-8 students use multicolored Epsom salt (magnesium sulfate) crystallizing solutions to reveal beautiful, cylindrical, 3-dimensional, needle-shaped structures. Through observations of the crystal art, students analyze factors that contribute to crystal size and formation, compare…

  4. Total immersion crystal growth

    NASA Technical Reports Server (NTRS)

    Morrison, Andrew D. (Inventor)

    1987-01-01

    Crystals of wide band gap materials are produced by positioning a holder receiving a seed crystal at the interface between a body of molten wide band gap material and an overlying layer of temperature-controlled, encapsulating liquid. The temperature of the layer decreases from the crystallization temperature of the crystal at the interface with the melt to a substantially lower temperature at which formation of crystal defects does not occur, suitably a temperature of 200 to 600 C. After initiation of crystal growth, the leading edge of the crystal is pulled through the layer until the leading edge of the crystal enters the ambient gas headspace which may also be temperature controlled. The length of the column of liquid encapsulant may exceed the length of the crystal such that the leading edge and trailing edge of the crystal are both simultaneously with the column of the crystal. The crystal can be pulled vertically by means of a pulling-rotation assembly or horizontally by means of a low-angle withdrawal mechanism.

  5. Protein Crystal Based Nanomaterials

    NASA Technical Reports Server (NTRS)

    Bell, Jeffrey A.; VanRoey, Patrick

    2001-01-01

    This is the final report on a NASA Grant. It concerns a description of work done, which includes: (1) Protein crystals cross-linked to form fibers; (2) Engineering of protein to favor crystallization; (3) Better knowledge-based potentials for protein-protein contacts; (4) Simulation of protein crystallization.

  6. Food Crystalization and Eggs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Food Crystalization and Eggs Deana R. Jones, Ph.D. USDA Agricultural Research Service Egg Safety and Quality Research Unit Athens, Georgia, USA Deana.Jones@ars.usda.gov Sugar, salt, lactose, tartaric acid and ice are examples of constituents than can crystallize in foods. Crystallization in a foo...

  7. Crystallization Processes and Magma Chamber Dynamics at the Mount Erebus Volcano Lava Lake: The Mineralogic Message

    NASA Astrophysics Data System (ADS)

    Kelly, P. J.; Kyle, P. R.; Dunbar, N. W.

    2006-12-01

    Mount Erebus volcano, Antarctica, hosts a persistently convecting and degassing lake of crystal-rich (30-40 vol.% phenocrysts) phonolite magma, providing a direct view into an active, stable, upper-level magma chamber. Mineral phases in lava bombs ejected by small strombolian eruptions from the lava lake between 1972 and 2004 were examined. Detailed compositional profiles of Ti-magnetite and large (up to 10 cm) anorthoclase feldspar phenocrysts were obtained by electron microprobe (EMP). The EMP data provide insight into the controls on crystallization in the lava lake/shallow magmatic system as well as the processes occurring in the magma chamber. Ti-magnetite are uniform and unzoned. The anorthoclase are complexly compositionally zoned over a restricted range (An10.3-22.9Ab62.8-68.1Or11.4-27.2) and contain abundant melt inclusions (up to ~30 vol. %). Coupled, inverse variations of An and Or account for ~96% of major element compositional variability and independent Ab variations account for ~4%. The anorthoclase compositions and textures suggest crystallization proceeds at low degrees of effective undercooling and is controlled by decompression-induced degassing of water. Unlike microlites that form during a single episode of ascent and eruption, the anorthoclase phenocrysts record multiple episodes of decompression and rim growth due to shallow convection in the lava lake under variable PH2O conditions. Crystals contained within a single lava bomb do not have shared crystallization histories, suggesting that differential movement of crystals and melt occurs within the magma chamber and that lava bombs are a mechanical assembly of crystals brought together a short time before or during an eruption. Large temperature variations at the surface of the lava lake (~400°C) are not reflected in the crystal compositions. Apparently, the kinetics of mineral growth are too sluggish to record the transient cooling (estimated to be ~20 mins.) experienced by crystals at the

  8. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0...

  9. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0...

  10. Production of a Large-Diameter Uniform ECR Plasma with a Lisitano Coil

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Takeuchi, Yoshiaki; Komori, Akio; Kawai, Yoshinobu

    1988-09-01

    A large-diameter uniform plasma was demonstrated to be produced by electron cyclotron resonance heating with a slotted Lisitano coil of 40 cm diameter. The diameter of the realized uniform plasma was found to be almost equal to that of the Lisitano coil. It was also suggested that the microwave is propagated in the whole region inside the Lisitano coil, and produces the uniform plasma.

  11. Measurement of Vein Diameter for Peripherally Inserted Central Catheter (PICC) Insertion: An Observational Study.

    PubMed

    Sharp, Rebecca; Cummings, Melita; Childs, Jessie; Fielder, Andrea; Mikocka-Walus, Antonina; Grech, Carol; Esterman, Adrian

    2015-01-01

    Choosing an appropriately sized vein reduces the risk of venous thromboembolism associated with peripherally inserted central catheters. This observational study described the diameters of the brachial, basilic, and cephalic veins and determined the effect of patient factors on vein size. Ultrasound was used to measure the veins of 176 participants. Vein diameter was similar in both arms regardless of hand dominance and side. Patient factors-including greater age, height, and weight, as well as male gender-were associated with increased vein diameter. The basilic vein tended to have the largest diameter statistically. However, this was the case in only 55% of patients. PMID:26339941

  12. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, David A.

    1982-01-01

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  13. Method and apparatus for determining diameter and wall thickness of minute hollow spherical shells

    DOEpatents

    Steinman, D.A.

    1980-05-30

    Method and apparatus for determining diameter and wall thickness of hollow microspheres or shells wherein terminal velocities of shells traveling in fluid-filled conduits of differing diameters are measured. A wall-effect factor is determined as a ratio of the terminal velocities, and shell outside diameter may then be ascertained as a predetermined empirical function of wall-effect factor. For shells of known outside diameter, wall thickness may then be ascertained as a predetermined empirical function of terminal velocity in either conduit.

  14. Relating Airway Diameter Distributions to Regular Branching Asymmetry in the Lung

    NASA Astrophysics Data System (ADS)

    Majumdar, Arnab; Alencar, Adriano M.; Buldyrev, Sergey V.; Hantos, Zoltán; Lutchen, Kenneth R.; Stanley, H. Eugene; Suki, Béla

    2005-10-01

    We study the distribution Πn(D) of airway diameters D as a function of generation N in asymmetric airway trees of mammalian lungs. We find that the airway bifurcations are self-similar in four species studied. Specifically, the ratios of diameters of the major and minor daughters to their parent are constants independent of N until a cutoff diameter is reached. We derive closed form expressions for ΠN(D) and examine the flow resistance of the tree based on an asymmetric flow division model. Our findings suggest that the observed diameter heterogeneity is consistent with an underlying regular branching asymmetry.

  15. Protein crystallization with paper

    NASA Astrophysics Data System (ADS)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  16. Crystallography of icosahedral crystals

    NASA Astrophysics Data System (ADS)

    Bak, P.

    The crystallography of icosahedral crystals is constructed. The actual three-dimensional crystal is represented by a three-dimensional cut in a regular six-dimensional periodic crystal with symmetry described by a six-dimensional space group, and the positions of atoms correspond to an arrangement of hypersurface segments. The resulting crystal cannot in general be viewed as a space-filling arrangemment of a small number of different Penrose tiles. The intensities of Bragg spots are given directly as the intensities of Bragg spots of the six-dimensional crystal.

  17. Photonic crystal light source

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu; Bur, James A.

    2004-07-27

    A light source is provided by a photonic crystal having an enhanced photonic density-of-states over a band of frequencies and wherein at least one of the dielectric materials of the photonic crystal has a complex dielectric constant, thereby producing enhanced light emission at the band of frequencies when the photonic crystal is heated. The dielectric material can be a metal, such as tungsten. The spectral properties of the light source can be easily tuned by modification of the photonic crystal structure and materials. The photonic crystal light source can be heated electrically or other heating means. The light source can further include additional photonic crystals that exhibit enhanced light emission at a different band of frequencies to provide for color mixing. The photonic crystal light source may have applications in optical telecommunications, information displays, energy conversion, sensors, and other optical applications.

  18. Protein Crystal Growth

    NASA Technical Reports Server (NTRS)

    2003-01-01

    In order to rapidly and efficiently grow crystals, tools were needed to automatically identify and analyze the growing process of protein crystals. To meet this need, Diversified Scientific, Inc. (DSI), with the support of a Small Business Innovation Research (SBIR) contract from NASA s Marshall Space Flight Center, developed CrystalScore(trademark), the first automated image acquisition, analysis, and archiving system designed specifically for the macromolecular crystal growing community. It offers automated hardware control, image and data archiving, image processing, a searchable database, and surface plotting of experimental data. CrystalScore is currently being used by numerous pharmaceutical companies and academic and nonprofit research centers. DSI, located in Birmingham, Alabama, was awarded the patent Method for acquiring, storing, and analyzing crystal images on March 4, 2003. Another DSI product made possible by Marshall SBIR funding is VaporPro(trademark), a unique, comprehensive system that allows for the automated control of vapor diffusion for crystallization experiments.

  19. Welding Molecular Crystals.

    PubMed

    Adolf, Cyril R R; Ferlay, Sylvie; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-12-16

    Both for fundamental and applied sciences, the design of complex molecular systems in the crystalline phase with strict control of order and periodicity at both microscopic and macroscopic levels is of prime importance for development of new solid-state materials and devices. The design and fabrication of complex crystalline systems as networks of crystals displaying task-specific properties is a step toward smart materials. Here we report on isostructural and almost isometric molecular crystals of different colors, their use for fabrication of core-shell crystals, and their welding by 3D epitaxial growth into networks of crystals as single-crystalline entities. Welding of crystals by self-assembly processes into macroscopic networks of crystals is a powerful strategy for the design of hierarchically organized periodic complex architectures composed of different subdomains displaying targeted characteristics. Crystal welding may be regarded as a first step toward the design of new hierarchically organized complex crystalline systems. PMID:26581391

  20. Crystallization of PTP Domains.

    PubMed

    Levy, Colin; Adams, James; Tabernero, Lydia

    2016-01-01

    Protein crystallography is the most powerful method to obtain atomic resolution information on the three-dimensional structure of proteins. An essential step towards determining the crystallographic structure of a protein is to produce good quality crystals from a concentrated sample of purified protein. These crystals are then used to obtain X-ray diffraction data necessary to determine the 3D structure by direct phasing or molecular replacement if the model of a homologous protein is available. Here, we describe the main approaches and techniques to obtain suitable crystals for X-ray diffraction. We include tools and guidance on how to evaluate and design the protein construct, how to prepare Se-methionine derivatized protein, how to assess the stability and quality of the sample, and how to crystallize and prepare crystals for diffraction experiments. While general strategies for protein crystallization are summarized, specific examples of the application of these strategies to the crystallization of PTP domains are discussed. PMID:27514806

  1. Quantification of pulmonary vessel diameter in low-dose CT images

    NASA Astrophysics Data System (ADS)

    Rudyanto, Rina D.; Ortiz de Solórzano, Carlos; Muñoz-Barrutia, Arrate

    2015-03-01

    Accurate quantification of vessel diameter in low-dose Computer Tomography (CT) images is important to study pulmonary diseases, in particular for the diagnosis of vascular diseases and the characterization of morphological vascular remodeling in Chronic Obstructive Pulmonary Disease (COPD). In this study, we objectively compare several vessel diameter estimation methods using a physical phantom. Five solid tubes of differing diameters (from 0.898 to 3.980 mm) were embedded in foam, simulating vessels in the lungs. To measure the diameters, we first extracted the vessels using either of two approaches: vessel enhancement using multi-scale Hessian matrix computation, or explicitly segmenting them using intensity threshold. We implemented six methods to quantify the diameter: three estimating diameter as a function of scale used to calculate the Hessian matrix; two calculating equivalent diameter from the crosssection area obtained by thresholding the intensity and vesselness response, respectively; and finally, estimating the diameter of the object using the Full Width Half Maximum (FWHM). We find that the accuracy of frequently used methods estimating vessel diameter from the multi-scale vesselness filter depends on the range and the number of scales used. Moreover, these methods still yield a significant error margin on the challenging estimation of the smallest diameter (on the order or below the size of the CT point spread function). Obviously, the performance of the thresholding-based methods depends on the value of the threshold. Finally, we observe that a simple adaptive thresholding approach can achieve a robust and accurate estimation of the smallest vessels diameter.

  2. Prediction of quadruple hamstring graft diameter for anterior cruciate ligament reconstruction by anthropometric measurements

    PubMed Central

    Asif, Naiyer; Ranjan, Rahul; Ahmed, Sohail; Sabir, Aamir B; Jilani, Latif Z; Qureshi, Owais A

    2016-01-01

    Background: The literature is scanty regarding the anthropometric predictors on the diameter of quadruple hamstring graft obtained in anterior cruciate ligament (ACL) reconstruction in Indian population. Minimum diameter of the graft for ACL reconstruction should be >7 mm to preclude failure. The objective of this study was to assess the prediction of the hamstring graft diameter by several anthropometric parameters including age, thigh circumference, weight, height and body mass index (BMI). Materials and Methods: 46 consecutive patients who had undergone ACL reconstruction by the same surgeon using quadruple hamstring grafts were evaluated. The age, thigh circumference of the normal side, height, weight and BMI were recorded preoperatively and Pearson correlation was done using these parameters with graft diameter measured intraoperatively. Regression analysis in a stepwise manner was undertaken to assess the influence of individual anthropometric parameters on the graft diameter. Results: There were 44 males and 2 females. Mean age was 29.4 years, mean height was 172.6 cm, mean weight was 70.9 kg, mean BMI was 23.8 kg/m2, mean thigh circumference was 47.1 cm and mean graft diameter was 7.9 mm. There was a positive correlation individually between the thigh circumference and graft diameter obtained (r = 0.8, P < 0.01, n = 46), and between the height and graft diameter (r = 0.8, P < 0.01, n = 46). On the regression analysis thigh circumference and height were found to be significant predictors of graft diameter giving the following equation: Graft diameter (mm) = 0. 079 height (cm) +0.068 thigh circumference (cm) −9.031. Conclusion: Preoperatively using the above equation if graft diameter came out to be <7 mm then alternate options of graft material must be kept in mind in order to prevent failure. PMID:26955176

  3. Macromolecular Crystallization in Microgravity

    NASA Technical Reports Server (NTRS)

    Snell, Edward H.; Helliwell, John R.

    2004-01-01

    The key concepts that attracted crystal growers, macromolecular or solid state, to microgravity research is that density difference fluid flows and sedimentation of the growing crystals are greatly reduced. Thus, defects and flaws in the crystals can be reduced, even eliminated, and crystal volume can be increased. Macromolecular crystallography differs from the field of crystalline semiconductors. For the latter, crystals are harnessed for their electrical behaviors. A crystal of a biological macromolecule is used instead for diffraction experiments (X-ray or neutron) to determine the three-dimensional structure of the macromolecule. The better the internal order of the crystal of a biological macromolecule then the more molecular structure detail that can be extracted. This structural information that enables an understanding of how the molecule functions. This knowledge is changing the biological and chemical sciences with major potential in understanding disease pathologies. Macromolecular structural crystallography in general is a remarkable field where physics, biology, chemistry, and mathematics meet to enable insight to the basic fundamentals of life. In this review, we examine the use of microgravity as an environment to grow macromolecular crystals. We describe the crystallization procedures used on the ground, how the resulting crystals are studied and the knowledge obtained from those crystals. We address the features desired in an ordered crystal and the techniques used to evaluate those features in detail. We then introduce the microgravity environment, the techniques to access that environment, and the theory and evidence behind the use of microgravity for crystallization experiments. We describe how ground-based laboratory techniques have been adapted to microgravity flights and look at some of the methods used to analyze the resulting data. Several case studies illustrate the physical crystal quality improvements and the macromolecular structural

  4. Growth and characterization of unidirectional (100) KDP single crystal by Sankaranarayanan-Ramasamy (SR) method.

    PubMed

    Balamurugan, S; Ramasamy, P

    2009-01-01

    Unidirectional (100) potassium dihydrogen orthophosphate (KDP) single crystals were grown by Sankaranarayanan-Ramasamy (SR) method. The (100) oriented seed crystals were mounted at the bottom of the glass ampoules and the crystals of 20mm diameter, 30 mm height and 15 mm diameter, 65 mm height were grown by SR method. The grown crystals were characterized by high-resolution X-ray diffractometry anlaysis, UV-vis spectroscopy, dielectric and microhardness studies. The high-resolution X-ray diffractometry anlaysis indicates that the crystalline perfection is excellent without having any very low angle internal structural grain boundaries. The SR method-grown unidirectional KDP has 15% higher transmittance compared to conventional method-grown crystals. The dielectric constant was higher and the dielectric loss was less in SR method-grown crystal. The crystals grown by SR method have much higher hardness value than conventional method-grown crystals. The quality of the crystal grown by SR method is better than conventional method-grown crystal. PMID:18805048

  5. Crystallization and crystal properties of squid rhodopsin

    SciTech Connect

    Murakami, Midori; Kitahara, Rei; Gotoh, Toshiaki; Kouyama, Tsutomu

    2007-06-01

    Truncated rhodopsin from the retina of the squid Todarodes pacificus was extracted and crystallized by the sitting-drop vapour-diffusion method. Hexagonal crystals grown in the presence of octylglucoside and ammonium sulfate diffracted to 2.8 Å resolution. Rhodopsin, a photoreceptor membrane protein in the retina, is a prototypical member of the G-protein-coupled receptor family. In this study, rhodopsin from the retina of the squid Todarodes pacificus was treated with V8 protease to remove the C-terminal extension. Truncated rhodopsin was selectively extracted from the microvillar membranes using alkyl glucoside in the presence of zinc ions and was then crystallized by the sitting-drop vapour-diffusion method. Of the various crystals obtained, hexagonal crystals grown in the presence of octylglucoside and ammonium sulfate diffracted to 2.8 Å resolution. The diffraction data suggested that the crystal belongs to space group P6{sub 2}, with unit-cell parameters a = b = 122.1, c = 158.6 Å. Preliminary crystallographic analysis, together with linear dichroism results, suggested that the rhodopsin dimers are packed in such a manner that their transmembrane helices are aligned nearly parallel to the c axis.

  6. Patch diameter limitation due to high chirp rates in focused SAR images

    NASA Astrophysics Data System (ADS)

    Doerry, Armin W.

    1994-10-01

    Polar-format processed synthetic aperture radar (SAR) images have a limited focused patch diameter that results from unmitigated phase errors. Very high chirp rates, encountered with fine-resolution short-pulse radars, exasperate the problem via a residual video phase error term. This letter modifies the traditional maximum patch diameter expression to include effects of very high chirp rates.

  7. Assessment of pubertal development of boars derived from ultrasonographic determination of testicular diameter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    At the onset of puberty, seminiferous tubules rapidly increase in diameter occupying a greater proportion of the testis with a consequent rapid increase in testicular size. The objective of the current studies was to evaluate the utility of ultrasonography to assess testicular diameter as a basis fo...

  8. A Method to Improve the Accuracy of Particle Diameter Measurements from Shadowgraph Images

    NASA Astrophysics Data System (ADS)

    Erinin, Martin A.; Wang, Dan; Liu, Xinan; Duncan, James H.

    2015-11-01

    A method to improve the accuracy of the measurement of the diameter of particles using shadowgraph images is discussed. To obtain data for analysis, a transparent glass calibration reticle, marked with black circular dots of known diameters, is imaged with a high-resolution digital camera using backlighting separately from both a collimated laser beam and diffuse white light. The diameter and intensity of each dot is measured by fitting an inverse hyperbolic tangent function to the particle image intensity map. Using these calibration measurements, a relationship between the apparent diameter and intensity of the dot and its actual diameter and position relative to the focal plane of the lens is determined. It is found that the intensity decreases and apparent diameter increases/decreases (for collimated/diffuse light) with increasing distance from the focal plane. Using the relationships between the measured properties of each dot and its actual size and position, an experimental calibration method has been developed to increase the particle-diameter-dependent range of distances from the focal plane for which accurate particle diameter measurements can be made. The support of the National Science Foundation under grant OCE0751853 from the Division of Ocean Sciences is gratefully acknowledged.

  9. Diameter prediction mathematical models for xanthan gum-alginate capsules produced by extrusion-dripping method

    NASA Astrophysics Data System (ADS)

    Ong, Hui-Yen; Lee, Boon-Beng; Zakaria, Zarina; Chan, Eng-Seng

    2015-05-01

    The aim of this work is to compare the applicability of particle diameter prediction mathematical models (i.e. Tate's Law equation, the modified Tate's Law equation, the modified Yildirim's model) to determine diameter of liquid core capsules. The capsules were produced by extruding xanthan gum-calcium chloride solution through a hypodermic needle into sodium alginate solution. The effects of two types of xanthan gum with different concentrations and needle diameters on capsule diameter were investigated in this work. The results showed that there was no significant difference in capsule diameter despite different types and concentrations of xanthan gum were used. However, the diameter of the capsules increased when the diameter of needles increased. As a whole, the produced capsules were in the range of 3.47 mm to 4.86 mm. Among the three studied prediction models, the modified Tate's Law mathematical equation was the most suitable model for the diameter prediction of the liquid core capsules with AAD of 2.74% and MAD of 6.55%.

  10. Scanning radiometer for measurement of forward-scattered light to determine mean diameter of spray particles

    NASA Technical Reports Server (NTRS)

    Buchele, D. R.

    1976-01-01

    A scanning radiometer is reported that measures forward-scattered light to determine the mean diameter of spray particles. An optical scanning method gives a continuous measurement of the light-scattering angle during spray nozzle tests. A method of calibration and a correction for background light are presented. Mean particle diameters of 10 to 500 micrometers can be measured.

  11. Effect of diameter of glass fibers on flexural properties of fiber-reinforced composites.

    PubMed

    Obukuro, Motofumi; Takahashi, Yutaka; Shimizu, Hiroshi

    2008-07-01

    This study investigated the effect of the diameter of glass fibers on the flexural properties of fiber-reinforced composites. Bar-shaped test specimens of highly filled fiber-reinforced composites (FRCs) and FRC of 30 vol% fiber content were made from a light-cured dimethacrylate monomer liquid (mixture of urethane dimethacrylate and triethylene glycol dimethacrylate) with silanized E-glass fibers (7, 10, 13, 16, 20, 25, 30, and 45 microm in diameter). Flexural strength and elastic modulus were measured. The flexural strength of the highly filled FRCs increased with increasing fiber diameter. In particular, the strengths of highly filled FRCs with 20-, 25-, 30-, and 45-microm-diameter fibers was significantly higher than the others (p<0.05). The flexural strength of FRC of 30 vol% fiber content increased with increasing fiber diameter, except for the FRC with 45-microm-diameter fibers; FRCs with 20-, 25-, and 30-microm-diameter fibers were significantly stronger than the others (p<0.05). Therefore, it was revealed that the diameter of glass fibers significantly affected the flexural properties of fiber-reinforced composites. PMID:18833767

  12. Biosensing using plasmonic nanohole arrays with small, homogenous and tunable aperture diameters.

    PubMed

    Xiong, Kunli; Emilsson, Gustav; Dahlin, Andreas B

    2016-06-21

    Plasmonic nanohole arrays are widely used for optical label-free molecular detection. An important factor for many applications is the diameter of the apertures. So far nanohole arrays with controllable diameters below 100 nm have not been demonstrated and it has not been systematically investigated how the diameter influences the optical properties. In this work we fine-tune the diameter in short range ordered nanohole arrays down to 50 nm. The experimental far field spectra show how the wavelength of maximum extinction remains unaffected while the transmission maximum blue shifts with smaller diameters. The near field is visualized by numerical simulations, showing a homogenous enhancement throughout the cylindrical void at the transmission maximum for diameters between 50 and 100 nm. For diameters below 50 nm plasmon excitation is no longer possible experimentally or by simulations. Further, we investigate the refractive index sensing capabilities of the smaller holes. As the diameter was reduced, the sensitivity in terms of resonance shift with bulk liquid refractive index was found to be unaltered. However, for the transmission maximum the sensitivity becomes more strongly localized to the hole interior. By directing molecular binding to the bottom of the holes we demonstrate how smaller holes enhance the sensitivity in terms of signal per molecule. A real-time detection limit well below one protein per nanohole is demonstrated. The smaller plasmonic nanoholes should be suitable for studies of molecules confined in small volumes and as mimics of biological nanopores. PMID:26867475

  13. Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights

    SciTech Connect

    Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K.

    2014-05-21

    Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650 nm and lengths from 8 to 18 μm. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ∼670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ∼660 nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

  14. The diameter of 88 Thisbe from its occultation of SAO 187124

    NASA Technical Reports Server (NTRS)

    Millis, R. L.; Wasserman, L. H.; Franz, O. G.; White, N. M.; Bowell, E.; Klemola, A.; Elliott, R. C.; Smethells, W. G.; Price, P. M.; Mckay, C. P.

    1982-01-01

    The 7 October, 1981 occultation of SAO 187124 by 88 Thisbe was observed at twelve sites. The occultation observations, together with information about the asteroid's light curve, gives a mean diameter for Thisbe of 232 + or - 10 km. This value is 10 percent larger than the previously published radiometric diameter of Thisbe.

  15. Automatic measurement of early gestational sac diameters from one scan session

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Chen, Siping; Li, Shengli; Wang, Tianfu

    2011-03-01

    Gestational sac (GS) diameters are commonly measured by routine ultrasound in early pregnancy. However, manually searching for the standardized plane of GS (SPGS) and measuring the diameters are time-consuming. In this paper, we develop a three-stage automatic solution for this procedure. In order to precisely and efficiently locate the position of GS in each frame, a coarse to fine GS detection scheme based on AdaBoost algorithm is explored. Then, an efficient method based on local context information is introduced to reduce the false positives (FP) generated by the above detection process. Finally, a database (DB) guided spectral segmentation is proposed to separate GS region from the background for further diameters measurement. Experiments carried out on 31 videos show that by using the proposed methods, the number of SPGS searching error is only one, and the average measurement error is 0.059 for the length diameters and 0.083 for the depth diameters.

  16. The Effect of Swelling Ratio on the Coulter Underestimation of Hydrogel Microsphere Diameters

    PubMed Central

    Pellegrini, Michael; Cherukupalli, Abhimanyu; Medini, Michael; Falkowski, Ron

    2015-01-01

    It has been demonstrated that the diameters of porous particles are underestimated by Coulter measurements. This phenomenon has also been observed in hydrogel particles, but not characterized. Since the Coulter principle uses the displacement of electrolyte to determine particle size, electrolyte contained within the swelled hydrogel microparticles results in an underestimate of actual particle diameters. The increased use of hydrogel microspheres in biomedical applications has led to the increased application of the Coulter principle to evaluate the size distribution of microparticles. A relationship between the swelling ratio of the particles and their reported Coulter diameters will permit calculation of the actual diameters of these particles. Using polyethylene glycol diacrylate hydrogel microspheres, we determined a correction factor that relates the polymer swelling ratio and the reported Coulter diameters to their actual size. PMID:26414785

  17. Magnetic-field-induced diameter-selective synthesis of single-walled carbon nanotubes.

    PubMed

    Su, Yanjie; Zhang, Yaozhong; Wei, Hao; Zhang, Liling; Zhao, Jiang; Yang, Zhi; Zhang, Yafei

    2012-03-01

    We report a facile and scalable approach to synthesize single-walled carbon nanotubes (SWNTs) with selected diameter distribution by applying a magnetic field perpendicular to the electric field in the arc plasma region. It is found that this magnetic field-induced diameter-selectivity strategy enables the control of the SWNTs with different diameter distributions in different regions, and the diameter-selective efficiency could be enhanced by modifying the direction of magnetic field. Our results indicate that the motions of the catalysts with different particle sizes, positive carbon ions and electrons are significantly influenced by the magnetic field and electromagnetic force, resulting in the different nucleation and growth processes of SWNTs due to the collective interactions between the magnetic field and arc plasma. This approach would enable a viable route towards the synthesis of SWNTs with desired diameter through the tuning of arc parameters in the arc discharge process. PMID:22301844

  18. A simple correction for slug tests in small-diameter wells

    USGS Publications Warehouse

    Butler, J.J., Jr.

    2002-01-01

    A simple procedure is presented for correcting hydraulic conductivity (K) estimates obtained from slug tests performed in small-diameter installations screened in highly permeable aquifers. Previously reported discrepancies between results from slug tests in small-diameter installations and those from tests in nearby larger-diameter wells are primarily a product of frictional losses within the small-diameter pipe. These frictional losses are readily incorporated into existing models for slug tests in high-K aquifers, which then serve as the basis of a straightforward procedure for correcting previously obtained K estimates. A demonstration of the proposed procedure using data from a series of slug tests performed in a controlled field setting confirms the validity of the approach. The results of this demonstration also reveal the detailed view of spatial variations in K that can be obtained using slug tests in small-diameter installations.

  19. Ultrahigh-resolution and non-contact diameter measurement of metallic wire using eddy current sensor.

    PubMed

    Li, Wei; Wang, Hongbo; Feng, Zhihua

    2014-08-01

    This paper proposes a new method using eddy current sensor (ECS) for online non-contact diameter measurement of metallic wires with ultrahigh resolution. A prototype sensor was designed, fabricated, and tested for copper wires with diameters ranging from 1.12 mm to 1.30 mm. A solenoid coil with dimensions of 16 mm long and 2.1 mm in diameter is used as sensing element with a working frequency of 1.3 MHz. With a well-designed bridge, the sensing coil's inductance variation can be detected and the wire's diameter can be calculated. The ECS system demonstrated a dynamic resolution better than 2.2 μm and a static resolution better than 0.42 nm for a wire with a diameter of 1.3 mm. This non-contact method has competitive advantages over other methods in many aspects, especially in terms of measurement resolution. PMID:25173300

  20. Studies on conventional and Sankaranarayanan-Ramasamy (SR) method grown ferroelectric glycine phosphite (GPI) single crystals

    NASA Astrophysics Data System (ADS)

    Senthil Pandian, M.; Pattanaboonmee, N.; Ramasamy, P.; Manyum, P.

    2011-01-01

    Transparent single crystals of glycine phosphite were grown by Sankaranarayanan-Ramasamy (SR) method and conventional slow evaporation solution technique (SEST) which had the sizes of 100 mm in length, 30 mm diameter and 10×11×8 mm 3. The conventional slow evaporation and Sankaranarayanan-Ramasamy method grown glycine phosphite single crystals were characterized using laser damage threshold, chemical etching, Vickers microhardness, UV-vis-NIR and dielectric analysis. The laser damage threshold value was higher in SR method grown GPI crystal as against conventional method grown crystal. The SR method grown GPI has higher hardness and also higher transmittance compared to conventional method grown crystal. The chemical etching and dielectric loss measurements indicate that the crystal grown by SR method has low density of defects and low value of dielectric loss compared to conventional method grown GPI crystal.

  1. Growth of negative solubility lithium sulfate monohydrate crystal by slow evaporation and Sankaranarayanan-Ramasamy method

    NASA Astrophysics Data System (ADS)

    Boopathi, K.; Rajesh, P.; Ramasamy, P.

    2012-04-01

    Single crystals of negatively soluble lithium sulfate monohydrate (LSMH) have been grown by conventional and Sankaranarayanan-Ramasamy (SR) methods. A negatively soluble material has been grown for the first time by the SR method. The size of the grown crystal is 40 mm length and 15 mm diameter. The solubility of the material has been found at different temperatures. The grown crystals were subjected to high resolution X-ray diffraction studies, UV-vis analysis, dielectric measurements, Vickers micro-hardness, piezoelectric measurements, laser damage threshold and second harmonic generation studies. Crystalline perfection of the grown crystals was analyzed using HRXRD. The grown crystals were found to be transparent in the entire visible region. The SR method grown crystal has higher hardness, lower dielectric loss, higher piezoelectric charge coefficient and higher laser stability compared to the conventional method grown crystal. The powder Kurtz method confirms that LSMH has SHG efficiency.

  2. Design and growth of lead selenoiodide semiconductors crystals for radiation detection

    NASA Astrophysics Data System (ADS)

    House, David; Singh, N. B.; Arnold, B.; Choa, Fow-Sen; Schreib, B.

    2014-09-01

    We have designed experiments utilizing for achieving desired bandgap resistivity, electron hole-pairs by solid solution materials. A low temperature synthesis, purification and growth to reduce stress and high yield for low defect density crystals of PbI2-PbSe system was developed for low cost large volume high efficiency detectors. This material system can be used for γ-ray detection. The material design is based on the heavy metal halide and selenide solid-solution system. This novel multicomponent crystal involves innovative approach for synthesis, purification and low temperature growth from the melt in modified three- zone Bridgman furnace. Crystals up to 15 mm diameter were grown and cm size slabs were fabricated for evaluation. Our approach for shaped crystal growth previously used for crystal is an exciting approach to increase the yield and further reduce the fabrication cost. Preliminary results show high resistivity and large crystal growth feasibility for crystals using parent components.

  3. Protein crystal growth

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Atomic force microscopy uses laser technology to reveal a defect, a double-screw dislocation, on the surface of this crystal of canavalin, a major source of dietary protein for humans and domestic animals. When a crystal grows, attachment kinetics and transport kinetics are competing for control of the molecules. As a molecule gets close to the crystal surface, it has to attach properly for the crystal to be usable. NASA has funded investigators to look at those attachment kinetics from a theoretical standpoint and an experimental standpoint. Dr. Alex McPherson of the University of California, Irvine, is one of those investigators. He uses X-ray diffraction and atomic force microscopy in his laboratory to answer some of the many questions about how protein crystals grow. Atomic force microscopy provides a means of looking at how individual molecules are added to the surface of growing protein crystals. This helps McPherson understand the kinetics of protein crystal growth. McPherson asks, How fast do crystals grow? What are the forces involved? Investigators funded by NASA have clearly shown that such factors as the level of supersaturation and the rate of growth all affect the habit [characteristic arrangement of facets] of the crystal and the defects that occur in the crystal.

  4. Common bile duct diameter in an asymptomatic population: A magnetic resonance imaging study

    PubMed Central

    Peng, Rong; Zhang, Ling; Zhang, Xiao-Ming; Chen, Tian-Wu; Yang, Lin; Huang, Xiao-Hua; Zhang, Ze-Ming

    2015-01-01

    AIM: To measure the common bile duct (CBD) diameter by magnetic resonance cholangiopancreatography (MRCP) in a large asymptomatic population and analyze its some affecting factors. METHODS: This study included 862 asymptomatic subjects who underwent MRCP. The CBD diameter was measured at its widest visible portion on regular end-expiration MRCP for all subjects. Among these 862 subjects, 221 volunteers also underwent end-inspiration MRCP to study the effect of respiration on the CBD diameter. The age, sex, respiration, body length, body weight, body mass index (BMI), portal vein diameter (PVD), length of the extrahepatic duct and CBD, cystic junction radial orientation and location were recorded. The subjects were divided into 7 groups according to age. All of the above factors were compared with the CBD diameter on end-expiration MRCP. RESULTS: Among the 862 subjects, the CBD diameter was 4.13 ± 1.11 mm (range, 1.76-9.45 mm) and was correlated with age (r = 0.484; P < 0.05), with a dilation of 0.033 mm per year. The upper limit of the 95% reference range was 5.95 mm, resulting in a reasonable upper limit of 6 mm for the asymptomatic population. Respiration and other factors, including sex, body length, body weight, BMI, PVD, length of the extrahepatic duct and CBD, cystic junction radial orientation and location, were not related to the CBD diameter. CONCLUSION: We established a reference range for the CBD diameter on MRCP for an asymptomatic population. The CBD diameter is correlated with age. Respiration did not affect the non-dilated CBD diameter. PMID:26753065

  5. Effects of Initial Pore Diameter on the Oil Absorption Behavior of Potato Chips during Frying Process.

    PubMed

    Li, Jinwei; Zhang, Tingting; Liu, Yuanfa; Fan, Liuping

    2016-01-01

    How initial pore diameter in materials affects oil absorption has been rarely studied up to now. Herein, we provided direct data evidence suggesting that the pore diameter prior to frying closely related to the oil absorption behavior. The pore had no significant effect on oil absorption of potato chips (p>0.05) when its diameter was 0.1 and 0.2 mm compared with the control. However, the oil absorption increased with the increasing of pore diameter when it was 0.3-1.2 mm. The oil absorption tended to be saturated at 0.9 mm pore diameter. In addition, we analyzed the moisture content, total oil (TO), surface oil (SO), penetrated surface oil (PSO) and structural oil (STO) contents of potato chips. The results when using palm oil showed that there was no significant difference in moisture, TO and STO contents of samples with pore diameter of 0.1 and 0.2 mm during the whole frying processing respectively compared with the control (p>0.05). When pore diameter was 0.3-1.2 mm, STO and TO contents significantly increased with the rising of the diameter (p<0.05). The SO content and PSO content dropped as increasing in frying time for the samples with different pore diameters. The equilibrium TO content of samples with 0.3-0.9 mm pore significantly increased with the rising of pore diameter, which was about 6.2-22.5% higher than that of the control. And there was no significant difference in the equilibrium TO contents of both samples of 1.2 mm and 0.9 mm pore (p>0.05). STO fraction gave the greatest contribution to the increment of oil absorption. PMID:27041514

  6. Single-crystal gallium nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Goldberger, Joshua; He, Rongrui; Zhang, Yanfeng; Lee, Sangkwon; Yan, Haoquan; Choi, Heon-Jin; Yang, Peidong

    2003-04-01

    Since the discovery of carbon nanotubes in 1991 (ref. 1), there have been significant research efforts to synthesize nanometre-scale tubular forms of various solids. The formation of tubular nanostructure generally requires a layered or anisotropic crystal structure. There are reports of nanotubes made from silica, alumina, silicon and metals that do not have a layered crystal structure; they are synthesized by using carbon nanotubes and porous membranes as templates, or by thin-film rolling. These nanotubes, however, are either amorphous, polycrystalline or exist only in ultrahigh vacuum. The growth of single-crystal semiconductor hollow nanotubes would be advantageous in potential nanoscale electronics, optoelectronics and biochemical-sensing applications. Here we report an `epitaxial casting' approach for the synthesis of single-crystal GaN nanotubes with inner diameters of 30-200nm and wall thicknesses of 5-50nm. Hexagonal ZnO nanowires were used as templates for the epitaxial overgrowth of thin GaN layers in a chemical vapour deposition system. The ZnO nanowire templates were subsequently removed by thermal reduction and evaporation, resulting in ordered arrays of GaN nanotubes on the substrates. This templating process should be applicable to many other semiconductor systems.

  7. Convective instability in protein crystal growth

    NASA Astrophysics Data System (ADS)

    Lima, D.; de Wit, A.

    2004-08-01

    The conditions for the onset of convection during protein crystalization from a solution are studied theoretically on the basis of diffusion-convection evolution equations for the concentrations coupled to the Navier-Stokes equation describing the flow velocity. We consider that the density of the solution depends on the concentration of two species, namely, a protein and a precipitating agent, a salt. While the protein is crystallized at the crystal/solution interface, the salt is rejected, and these mechanisms are described by means of boundary conditions for the interface. We find the base profiles for both protein and salt concentrations and perform a linear stability analysis of this basic state with regard to buoyancy induced perturbations. This gives information on the critical diameter of capillaries above which convection may be observed, as well as on the influence of the speed of growth V of the crystal interface on the stability of the system. Numerical integration of the model shows good agreement with the predictions of the linear stability analysis.

  8. Unidirectional growth of benzophenone single crystals from solution

    NASA Astrophysics Data System (ADS)

    Ramasamy, P.

    2008-04-01

    Uniaxial benzophenone crystals along (1 1 0), (0 1 0), and (1 0 0)-oriented were grown by uniaxially solution-crystallization method of Sankaranarayanan-Ramasamy (SR). The experimental parameters involved in the present study were investigated in detail and a constant growth rate was achieved by compensating the loss of growth units in the solution. A transparent uniaxial benzophenone crystal having dimension of 500 mm length and 55 mm diameter was grown at room temperature for the first time in the literature. In contrast to the conventional solution growth method, the growth rate along each direction was measured at ease during the respective growth experiment by monitoring the elevation of the solid-liquid interface. The scaling up was found to be less complicated compared to hitherto known crystal growth methods.

  9. The role of nanopore shape in surface-induced crystallization

    NASA Astrophysics Data System (ADS)

    Diao, Ying; Harada, Takuya; Myerson, Allan S.; Alan Hatton, T.; Trout, Bernhardt L.

    2011-11-01

    Crystallization of a molecular liquid from solution often initiates at solid-liquid interfaces, and nucleation rates are generally believed to be enhanced by surface roughness. Here we show that, on a rough surface, the shape of surface nanopores can also alter nucleation kinetics. Using lithographic methods, we patterned polymer films with nanopores of various shapes and found that spherical nanopores 15-120 nm in diameter hindered nucleation of aspirin crystals, whereas angular nanopores of the same size promoted it. We also show that favourable surface-solute interactions are required for angular nanopores to promote nucleation, and propose that pore shape affects nucleation kinetics through the alteration of the orientational order of the crystallizing molecule near the angles of the pores. Our findings have clear technological implications, for instance in the control of pharmaceutical polymorphism and in the design of ‘seed’ particles for the regulation of crystallization of fine chemicals.

  10. Crystallization of Macromolecules

    PubMed Central

    Friedmann, David; Messick, Troy; Marmorstein, Ronen

    2014-01-01

    X-ray crystallography has evolved into a very powerful tool to determine the three-dimensional structure of macromolecules and macromolecular complexes. The major bottleneck in structure determination by X-ray crystallography is the preparation of suitable crystalline samples. This unit outlines steps for the crystallization of a macromolecule, starting with a purified, homogeneous sample. The first protocols describe preparation of the macromolecular sample (i.e., proteins, nucleic acids, and macromolecular complexes). The preparation and assessment of crystallization trials is then described, along with a protocol for confirming whether the crystals obtained are composed of macromolecule as opposed to a crystallization reagent . Next, the optimization of crystallization conditions is presented. Finally, protocols that facilitate the growth of larger crystals through seeding are described. PMID:22045560

  11. Automated macromolecular crystallization screening

    DOEpatents

    Segelke, Brent W.; Rupp, Bernhard; Krupka, Heike I.

    2005-03-01

    An automated macromolecular crystallization screening system wherein a multiplicity of reagent mixes are produced. A multiplicity of analysis plates is produced utilizing the reagent mixes combined with a sample. The analysis plates are incubated to promote growth of crystals. Images of the crystals are made. The images are analyzed with regard to suitability of the crystals for analysis by x-ray crystallography. A design of reagent mixes is produced based upon the expected suitability of the crystals for analysis by x-ray crystallography. A second multiplicity of mixes of the reagent components is produced utilizing the design and a second multiplicity of reagent mixes is used for a second round of automated macromolecular crystallization screening. In one embodiment the multiplicity of reagent mixes are produced by a random selection of reagent components.

  12. Single Crystal Membranes

    NASA Technical Reports Server (NTRS)

    Stormont, R. W.; Morrison, A.

    1974-01-01

    Single crystal a- and c-axis tubes and ribbons of sodium beta-alumina and sodium magnesium beta-alumina were grown from sodium oxide rich melts. Additional experiments grew ribbon crystals containing sodium magnesium beta, beta double prime, beta triple prime, and beta quadruple prime. A high pressure crystal growth chamber, sodium oxide rich melts, and iridium for all surfaces in contact with the melt were combined with the edge-defined, film-fed growth technique to grow the single crystal beta-alumina tubes and ribbons. The crystals were characterized using metallographic and X-ray diffraction techniques, and wet chemical analysis was used to determine the sodium, magnesium, and aluminum content of the grown crystals.

  13. Function photonic crystals

    NASA Astrophysics Data System (ADS)

    Wu, Xiang-Yao; Zhang, Bai-Jun; Yang, Jing-Hai; Liu, Xiao-Jing; Ba, Nuo; Wu, Yi-Heng; Wang, Qing-Cai

    2011-07-01

    In this paper, we present a new kind of function photonic crystals (PCs), whose refractive index is a function of space position. Conventional PCs structure grows from two materials, A and B, with different dielectric constants εA and εB. Based on Fermat principle, we give the motion equations of light in one-dimensional, two-dimensional and three-dimensional function photonic crystals. For one-dimensional function photonic crystals, we give the dispersion relation, band gap structure and transmissivity, and compare them with conventional photonic crystals, and we find the following: (1) For the vertical and non-vertical incidence light of function photonic crystals, there are band gap structures, and for only the vertical incidence light, the conventional PCs have band gap structures. (2) By choosing various refractive index distribution functions n( z), we can obtain more wider or more narrower band gap structure than conventional photonic crystals.

  14. Antarctic stratospheric ice crystals

    SciTech Connect

    Goodman, J. ); Toon, O.B.; Pueschel, R.F.; Snetsinger, K.G. ) Verma, S. )

    1989-11-30

    Ice crystals were replicated over the Palmer Peninsula at approximately 72{degree}S on six occasions during the 1987 Airborne Antarctic Ozone Experiment. The sampling altitude was between 12.5 and 18.5 km (45-65 thousand ft pressure altitude) with the temperature between 190 and 201 K. The atmosphere was subsaturated with respect to ice in all cases. The collected crystals were predominantly solid and hollow columns. The largest crystals were sampled at lower altitudes where the potential temperature was below 400 K. While the crystals were larger than anticipated, their low concentration results in a total surface area that is less than one tenth of the total aerosol surface area. The large ice crystals may play an important role in the observed stratospheric dehydration processes through sedimentation. Evidence of scavenging of submicron particles further suggests that the ice crystals may be effective in the removal of stratospheric chemicals.

  15. Growth of β-Ga2O3 single crystals using vertical Bridgman method in ambient air

    NASA Astrophysics Data System (ADS)

    Hoshikawa, K.; Ohba, E.; Kobayashi, T.; Yanagisawa, J.; Miyagawa, C.; Nakamura, Y.

    2016-08-01

    A new approach to β-Ga2O3 single crystal growth was studied, using the vertical Bridgman (VB) method in ambient air, while measuring the β-Ga2O3 melting temperature and investigating the effects of crucible composition and shape. β-Ga2O3 single crystals 25 mm in diameter were grown in platinum-rhodium alloy crucibles in ambient air, with no adhesion of the crystals to the crucible wall. Single crystal growth without a crystal seed was realized by (100) faceted growth with a growth direction perpendicular to the (100) faceted plane.

  16. Mercury iodide crystal growth

    NASA Technical Reports Server (NTRS)

    Cadoret, R.

    1982-01-01

    The purpose of the Mercury Iodide Crystal Growth (MICG) experiment is the growth of near-perfect single crystals of mercury Iodide (HgI2) in a microgravity environment which will decrease the convection effects on crystal growth. Evaporation and condensation are the only transformations involved in this experiment. To accomplish these objectives, a two-zone furnace will be used in which two sensors collect the temperature data (one in each zone).

  17. Charge transport in single crystal organic semiconductors

    NASA Astrophysics Data System (ADS)

    Xie, Wei

    Organic electronics have engendered substantial interest in printable, flexible and large-area applications thanks to their low fabrication cost per unit area, chemical versatility and solution processability. Nevertheless, fundamental understanding of device physics and charge transport in organic semiconductors lag somewhat behind, partially due to ubiquitous defects and impurities in technologically useful organic thin films, formed either by vacuum deposition or solution process. In this context, single-crystalline organic semiconductors, or organic single crystals, have therefore provided the ideal system for transport studies. Organic single crystals are characterized by their high chemical purity and outstanding structural perfection, leading to significantly improved electrical properties compared with their thin-film counterparts. Importantly, the surfaces of the crystals are molecularly flat, an ideal condition for building field-effect transistors (FETs). Progress in organic single crystal FETs (SC-FETs) is tremendous during the past decade. Large mobilities ~ 1 - 10 cm2V-1s-1 have been achieved in several crystals, allowing a wide range of electrical, optical, mechanical, structural, and theoretical studies. Several challenges still remain, however, which are the motivation of this thesis. The first challenge is to delineate the crystal structure/electrical property relationship for development of high-performance organic semiconductors. This thesis demonstrates a full spectrum of studies spanning from chemical synthesis, single crystal structure determination, quantum-chemical calculation, SC-OFET fabrication, electrical measurement, photoelectron spectroscopy characterization and extensive device optimization in a series of new rubrene derivatives, motivated by the fact that rubrene is a benchmark semiconductor with record hole mobility ~ 20 cm2V-1s-1. With successful preservation of beneficial pi-stacking structures, these rubrene derivatives form

  18. Phononic crystal devices

    DOEpatents

    El-Kady, Ihab F.; Olsson, Roy H.

    2012-01-10

    Phononic crystals that have the ability to modify and control the thermal black body phonon distribution and the phonon component of heat transport in a solid. In particular, the thermal conductivity and heat capacity can be modified by altering the phonon density of states in a phononic crystal. The present invention is directed to phononic crystal devices and materials such as radio frequency (RF) tags powered from ambient heat, dielectrics with extremely low thermal conductivity, thermoelectric materials with a higher ratio of electrical-to-thermal conductivity, materials with phononically engineered heat capacity, phononic crystal waveguides that enable accelerated cooling, and a variety of low temperature application devices.

  19. Crystal Formation in Inflammation.

    PubMed

    Franklin, Bernardo S; Mangan, Matthew S; Latz, Eicke

    2016-05-20

    The formation and accumulation of crystalline material in tissues is a hallmark of many metabolic and inflammatory conditions. The discovery that the phase transition of physiologically soluble substances to their crystalline forms can be detected by the immune system and activate innate immune pathways has revolutionized our understanding of how crystals cause inflammation. It is now appreciated that crystals are part of the pathogenesis of numerous diseases, including gout, silicosis, asbestosis, and atherosclerosis. In this review we discuss current knowledge of the complex mechanisms of crystal formation in diseased tissues and their interplay with the nutrients, metabolites, and immune cells that account for crystal-induced inflammation. PMID:26772211

  20. Liquid Crystal Optofluidics

    SciTech Connect

    Vasdekis, Andreas E.; Cuennet, J. G.; Psaltis, D.

    2012-10-11

    By employing anisotropic fluids and namely liquid crystals, fluid flow becomes an additional degree of freedom in designing optofluidic devices. In this paper, we demonstrate optofluidic liquid crystal devices based on the direct flow of nematic liquid crystals in microfluidic channels. Contrary to previous reports, in the present embodiment we employ the effective phase delay acquired by light travelling through flowing liquid crystal, without analysing the polarisation state of the transmitted light. With this method, we demonstrate the variation in the diffraction pattern of an array of microfluidic channels acting as a grating. We also discuss our recent activities in integrating mechanical oscillators for on-chip peristaltic pumping.