WorldWideScience

Sample records for buses by size

  1. COMPARISON OF CLEAN DIESEL BUSES TO CNG BUSES

    Energy Technology Data Exchange (ETDEWEB)

    Lowell, D.; Parsley, W.; Bush,C; Zupo, D.

    2003-08-24

    Using previously published data on regulated and unregulated emissions, this paper will compare the environmental performance of current generation transit buses operated on compressed natural gas (CNG) to current generation transit buses operated on ultra low sulfur diesel fuel (ULSD) and incorporating diesel particulate filters (DPF). Unregulated emissions evaluated include toxic compounds associated with adverse health effects (carbonyl, PAH, NPAH, benzene) as well as PM particle count and size distribution. For all regulated and unregulated emissions, both technologies are shown to be comparable. DPF equipped diesel buses and CNG buses have virtually identical levels of PM mass emissions and particle number emissions. DPF-equipped diesel buses have lower HC and CO emissions and lower emissions of toxic substances such as benzene, carbonyls and PAHs than CNG buses. CNG buses have lower NOx emissions than DPF-equipped buses, though CNG bus NOx emissions are shown to be much more variable. In addition, this paper will compare the capital and operating costs of CNG and DPF-equipped buses. The cost comparison is primarily based on the experience of MTA New York City Transit in operating CNG buses since 1995 and DPF-equipped buses fueled with ULSD since 2001. Published data on the experience of other large transit agencies in operating CNG buses is used to validate the NYCT experience. The incremental cost (compared to ''baseline'' diesel) of operating a typical 200-bus depot is shown to be six times higher for CNG buses than for ''clean diesel'' buses. The contributors to this increased cost for CNG buses are almost equally split between increased capital costs for purchase of buses and installation of fueling infrastructure, and increased operating costs for purchase of fuel, bus maintenance, and fuel station maintenance.

  2. Real-world operation conditions and on-road emissions of Beijing diesel buses measured by using portable emission measurement system and electric low-pressure impactor.

    Science.gov (United States)

    Liu, Zhihua; Ge, Yunshan; Johnson, Kent C; Shah, Asad Naeem; Tan, Jianwei; Wang, Chu; Yu, Linxiao

    2011-03-15

    On-road measurement is an effective method to investigate real-world emissions generated from vehicles and estimate the difference between engine certification cycles and real-world operating conditions. This study presents the results of on-road measurements collected from urban buses which propelled by diesel engine in Beijing city. Two widely used Euro III emission level buses and two Euro IV emission level buses were chosen to perform on-road emission measurements using portable emission measurement system (PEMS) for gaseous pollutant and Electric Low Pressure Impactor (ELPI) for particulate matter (PM) number emissions. The results indicate that considerable discrepancies of engine operating conditions between real-world driving cycles and engine certification cycles have been observed. Under real-world operating conditions, carbon monoxide (CO) and hydrocarbon (HC) emissions can easily meet their respective regulations limits, while brake specification nitrogen oxide (bsNO(x)) emissions present a significant deviation from its corresponding limit. Compared with standard limits, the real-world bsNO(x) emission of the two Euro III emission level buses approximately increased by 60% and 120% respectively, and bsNO(x) of two Euro IV buses nearly twice standard limits because Selective Catalytic Reduction (SCR) system not active under low exhaust temperature. Particle mass were estimated via particle size distribution with the assumption that particle density and diameter is liner. The results demonstrate that nanometer size particulate matter make significant contribution to total particle number but play a minor role to total particle mass. It is suggested that specific certified cycle should be developed to regulate bus engines emissions on the test bench or use PEMS to control the bus emissions under real-world operating conditions.

  3. Particle and gaseous emissions from individual diesel and CNG buses

    Science.gov (United States)

    Hallquist, Å. M.; Jerksjö, M.; Fallgren, H.; Westerlund, J.; Sjödin, Å.

    2013-05-01

    In this study size-resolved particle and gaseous emissions from 28 individual diesel-fuelled and 7 compressed natural gas (CNG)-fuelled buses, selected from an in-use bus fleet, were characterised for real-world dilution scenarios. The method used was based on using CO2 as a tracer of exhaust gas dilution. The particles were sampled by using an extractive sampling method and analysed with high time resolution instrumentation EEPS (10 Hz) and CO2 with a non-dispersive infrared gas analyser (LI-840, LI-COR Inc. 1 Hz). The gaseous constituents (CO, HC and NO) were measured by using a remote sensing device (AccuScan RSD 3000, Environmental System Products Inc.). Nitrogen oxides, NOx, were estimated from NO by using default NO2/NOx ratios from the road vehicle emission model HBEFA3.1. The buses studied were diesel-fuelled Euro III-V and CNG-fuelled Enhanced Environmentally Friendly Vehicles (EEVs) with different after-treatment, including selective catalytic reduction (SCR), exhaust gas recirculation (EGR) and with and without diesel particulate filter (DPF). The primary driving mode applied in this study was accelerating mode. However, regarding the particle emissions also a constant speed mode was analysed. The investigated CNG buses emitted on average a higher number of particles but less mass compared to the diesel-fuelled buses. Emission factors for number of particles (EFPN) were EFPN, DPF = 4.4 ± 3.5 × 1014, EFPN, no DPF = 2.1 ± 1.0 × 1015 and EFPN, CNG = 7.8 ± 5.7 ×1015 kg fuel-1. In the accelerating mode, size-resolved emission factors (EFs) showed unimodal number size distributions with peak diameters of 70-90 nm and 10 nm for diesel and CNG buses, respectively. For the constant speed mode, bimodal average number size distributions were obtained for the diesel buses with peak modes of ~10 nm and ~60 nm. Emission factors for NOx expressed as NO2 equivalents for the diesel buses were on average 27 ± 7 g (kg fuel)-1 and for the CNG buses 41 ± 26 g (kg

  4. Particle and gaseous emissions from individual diesel and CNG buses

    Directory of Open Access Journals (Sweden)

    Å. M. Hallquist

    2013-05-01

    Full Text Available In this study size-resolved particle and gaseous emissions from 28 individual diesel-fuelled and 7 compressed natural gas (CNG-fuelled buses, selected from an in-use bus fleet, were characterised for real-world dilution scenarios. The method used was based on using CO2 as a tracer of exhaust gas dilution. The particles were sampled by using an extractive sampling method and analysed with high time resolution instrumentation EEPS (10 Hz and CO2 with a non-dispersive infrared gas analyser (LI-840, LI-COR Inc. 1 Hz. The gaseous constituents (CO, HC and NO were measured by using a remote sensing device (AccuScan RSD 3000, Environmental System Products Inc.. Nitrogen oxides, NOx, were estimated from NO by using default NO2/NOx ratios from the road vehicle emission model HBEFA3.1. The buses studied were diesel-fuelled Euro III–V and CNG-fuelled Enhanced Environmentally Friendly Vehicles (EEVs with different after-treatment, including selective catalytic reduction (SCR, exhaust gas recirculation (EGR and with and without diesel particulate filter (DPF. The primary driving mode applied in this study was accelerating mode. However, regarding the particle emissions also a constant speed mode was analysed. The investigated CNG buses emitted on average a higher number of particles but less mass compared to the diesel-fuelled buses. Emission factors for number of particles (EFPN were EFPN, DPF = 4.4 ± 3.5 × 1014, EFPN, no DPF = 2.1 ± 1.0 × 1015 and EFPN, CNG = 7.8 ± 5.7 ×1015 kg fuel−1. In the accelerating mode, size-resolved emission factors (EFs showed unimodal number size distributions with peak diameters of 70–90 nm and 10 nm for diesel and CNG buses, respectively. For the constant speed mode, bimodal average number size distributions were obtained for the diesel buses with peak modes of ~10 nm and ~60 nm. Emission factors for NOx expressed as NO2 equivalents for the diesel buses were on average 27 ± 7 g (kg fuel−1 and for the CNG buses 41

  5. SIMPLIFIED METHOD FOR CALCULATING CLOSING IN OF SWITCH-GEAR FLEXIBLE BUSES AT SHORT CIRCUIT BY IMPULSE OF ELECTRODYNAMIC FORCES

    Directory of Open Access Journals (Sweden)

    I. I. Sergey

    2005-01-01

    Full Text Available The paper contains description of a simplified method for calculating closing-in of switch-gear flexible buses at short circuit. The developed method is based on integral and energy principles of  mechanics. In order to increase accuracy of the calculation corrections factors are introduced in an explicit formula for calculation of maximum horizontal deviations. These factors have been obtained with the help of a computer program that realized numerical method for calculating closing-in of wires by flexible thread levels.Diagrams are constructed with the purpose to find ymax and criteria of electro-dynamic resistance of flexible buses (permissible impulse of electro-dynamic forces and current of electro-dynamic resistance is determined.

  6. Processor arrays with asynchronous TDM optical buses

    Science.gov (United States)

    Li, Y.; Zheng, S. Q.

    1997-04-01

    We propose a pipelined asynchronous time division multiplexing optical bus. Such a bus can use one of the two hardwared priority schemes, the linear priority scheme and the round-robin priority scheme. Our simulation results show that the performances of our proposed buses are significantly better than the performances of known pipelined synchronous time division multiplexing optical buses. We also propose a class of processor arrays connected by pipelined asynchronous time division multiplexing optical buses. We claim that our proposed processor array not only have better performance, but also have better scalabilities than the existing processor arrays connected by pipelined synchronous time division multiplexing optical buses.

  7. Particle and gaseous emissions from individual diesel and CNG buses

    Directory of Open Access Journals (Sweden)

    Å. M. Hallquist

    2012-10-01

    Full Text Available In this study size-resolved particle and gaseous emissions from 28 individual diesel-fuelled and 7 compressed natural gas (CNG-fuelled buses, selected from an in-use bus fleet, were characterised for real-world dilution scenarios. The method used was based on using CO2 as a tracer of exhaust gas dilution. The particles were sampled by using an extractive sampling method and analysed with high time resolution instrumentation EEPS (10 Hz and CO2 with non-dispersive infrared gas analyser (LI-840, LI-COR Inc. 1 Hz. The gaseous constituents (CO, HC and NO were measured by using a remote sensing device (AccuScan RSD 3000, Environmental System Products Inc.. Nitrogen oxides, NOx, were estimated from NO by using default NO2/NOx ratios from the road vehicle emission model HBEFA 3.1. The buses studied were diesel-fuelled Euro II–V and CNG-fuelled Enhanced Environmental Friendly Vehicles (EEVs with different after-treatment, including selective catalytic reduction (SCR, exhaust gas recirculation (EGR and with and without diesel particulate filter (DPF. The primary driving mode applied in this study was accelerating mode. However, regarding the particle emissions also a constant speed mode was analysed. The investigated CNG buses emitted on average higher number of particles but less mass compared to the diesel-fuelled buses. Emission factors for number of particles (EFPN were EFPN, DPF = 8.0 ± 3.1 × 1014, EFPN, no DPF =2.8 ± 1.6 × 1015 and EFPN, CNG = 7.8 ± 5.7 × 1015 (kg fuel−1. In the accelerating mode size-resolved EFs showed unimodal number size distributions with peak diameters of 70–90 nm and 10 nm for diesel and CNG buses, respectively. For the constant speed mode bimodal average number size distributions were obtained for the diesel buses with peak modes of ~10 nm and ~60 nm.

    Emission

  8. Project Startup: Evaluating the Performance of Electric Buses

    Energy Technology Data Exchange (ETDEWEB)

    2016-04-01

    The National Renewable Energy Laboratory (NREL) is evaluating the in-service performance of fast-charge battery electric buses compared to compressed natural gas (CNG) buses operated by Foothill Transit in West Covina, California. Launched in 2015 in collaboration with the California Air Resources Board, this study aims to improve understanding of the overall use and effectiveness of fast-charge electric buses and associated charging infrastructure in transit operation.

  9. 佛山市发展公交车尾气削减潜力分析%Emission Reduction Potentiality by Developing Buses in Foshan

    Institute of Scientific and Technical Information of China (English)

    包艳萍; 刘永红; 黄建彰; 徐伟嘉

    2013-01-01

    Emission factors of buses, motorcycles and passenger cars of Foshan City, Guangdong Province were calculated with COPERT Ⅳ model integrated with information regarding amounts and annual mileages, case analysis was done for their emission, environmental effects and emissions reduction potentiality of buses.Results indicated that buses emission in Foshan in 2011 was 804.57 t CO,283.85 t VOC,3 365.32 t NOx and 73.00 t PM.Emissions of CO and VOC of buses were less than that of motorcycles and passenger cars, but emission of NOx was more.Emission of buses for one person travelling one kilometer would decrease by 32.00%,51.43% and 57.50% by increasing the number of passengers from 17 to 25,35 and 45.Annual emissions could be reduced by 611.66 t CO, 151.6 t VOC, 1,231.18 t NOx and 58.39 t PM respectively by changing all the emission standard of diesel buses from lower to Euro Ⅳ.Annual emissions could be reduced by 293.71 t CO, 2 086.87 t NOx and 70.34 t PM by changing diesel buses to environmentally-friendly vehicle (EEV) CNG buses, but annual emissions of VOC increased by 228.01 t.%采用COPERTⅣ模型计算佛山市公交车、摩托车和小型客车排放因子,结合保有量、年平均行驶里程计算其排放量,对佛山市公交车出行环境效果及尾气削减潜力进行情景分析.结果表明:2011年佛山市公交车CO 、VOC 、NOx和PM的排放量为804.57、283.85、3 365.32和73.00 t.单人单次公交车出行CO和VOC的排放量较摩托车和小型客车低,但NOx则较高.公交车载客人数从17人上升至25、35、45人,单人单次出行每公里排放量分别下降32.00%、51.43%和57.50%.佛山市低排放标准的柴油公交车全部更换成国Ⅳ排放标准柴油车、CO、VOC、NOx和PM的年排放量分别削减611.66、151.6、1 231.18和58.39 t.EEV标准天然气公交车替代柴油公交车可减少NOx和PM的排放,但对VOC的削减并无优势.佛山市现有柴油公交车更换

  10. School Buses Answer Calls for Help in Crises

    Science.gov (United States)

    Borja, Rhea R.

    2005-01-01

    Five days after Hurricane Katrina struck New Orleans, a convoy of 142 air-conditioned school buses from the 209,000-student Texas district rumbled to life. Loaded with food and bottled water, staffed by 350 school employees, and accompanied by bus-repair trucks and a phalanx of school police cars, the yellow buses traveled all night to reach the…

  11. SIMPLIFIED METHOD FOR CALCULATING CLOSING IN OF SWITCH-GEAR FLEXIBLE BUSES AT SHORT CIRCUIT BY IMPULSE OF ELECTRODYNAMIC FORCES

    OpenAIRE

    I. I. Sergey; E. G. Ponomarenko; W. M. Sammur; P. I. Klimkovich

    2005-01-01

    The paper contains description of a simplified method for calculating closing-in of switch-gear flexible buses at short circuit. The developed method is based on integral and energy principles of  mechanics. In order to increase accuracy of the calculation corrections factors are introduced in an explicit formula for calculation of maximum horizontal deviations. These factors have been obtained with the help of a computer program that realized numerical method for calculating closing-in of wi...

  12. The School Busing Controversy: 1970-75.

    Science.gov (United States)

    Buncher, Judith F., Ed.

    Even though transportation of school children was long accepted by the public prior to the conflict over school integration, the school bus became a symbol representing the divergent emotions of both the integrationists and the supporters of "neighborhood schools." Busing was used as a means of overcoming the resistance and procrastination of…

  13. The New Energy Buses in China

    DEFF Research Database (Denmark)

    Wang, Jingyu; Liu, Yingqi; Kokko, Ari

    2013-01-01

    With the advent of “low carbon” economy, new energy vehicles are increasingly favored by the Chinese government and manufacturers. New energy buses have become an important channel for the promotion of new energy utilizations. Based on the summary of policies, this paper conducts a thorough resea...... price. We draw the conclusions that clear direction and detailed plans will enhance the new energy bus promotion and rising oil prices will promote new energy buses as well.......With the advent of “low carbon” economy, new energy vehicles are increasingly favored by the Chinese government and manufacturers. New energy buses have become an important channel for the promotion of new energy utilizations. Based on the summary of policies, this paper conducts a thorough...... research on the technology and promotion achievements on new energy buses. We have found that the promotion achievements have difference with plans and gaps exist in different cities. In the paper we discuss the policy efficiency, the correlation between achievements, policies and the influence from oil...

  14. Electric Buses in Urban Transport, The Situation and Development Trends

    Institute of Scientific and Technical Information of China (English)

    Jakub Slavlk

    2014-01-01

    A study called "E-mobilita v MHD" (e-mobility in urban mass transit) has been conducted by the author's private consultancy to inform Czech public transport operators about the technologies and operational experience to date and stimulate the e-bus utilization as well as their involvement in e-bus research and development projects. The study covers trolley-buses, diesel hybrids and e-buses including fuel cell buses. These electric urban buses have been compared with combustion engine vehicles represented by diesel and CNG (compressed natural gas) buses, in terms of energy consumption and cost, greenhouse gas emissions, noise and life cycle cost. Relations between urban transport e-mobility and the "smart grid" concept have been presented as well. Comprehensive reports prepared on the European Union and the USA levels have been the basis for the study, completed by information from the field research, focused especially on the bus operational reliability and other parameters important for a transport operator and covering, interalia, 12 case studies. The results show electric buses as a promising urban transport mode with massive technology development overcoming their operational limitations. Synergies between electric buses and other urban systems, such as power supply, are notable as well.

  15. Evaluation of Orion/BAE Hybrid Buses and Orion CNG Buses at New York City Transit: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, L.; Barnitt, R.; Chandler, K.

    2005-05-01

    This paper prepared for the 2005 American Public Transportation Association Bus & Paratransit Conference discusses the NREL/DOE evaluation of hybrid electric transit buses operated by New York City Transit.

  16. Seat Belts in School Buses: A Study by the Wisconsin Department of Public Instruction Prepared for the Wisconsin Legislature: S.B.7. Bulletin No. 9078.

    Science.gov (United States)

    Richards, William T.

    The hypothesis of this study was that installation and use of seat belts in all large school buses are needed to prevent injuries and deaths to children in accidents as a result of no seat belts. Basic questions and summary arguments for and against the use of seat belts are listed. An analysis of research studies done on seat belts in school…

  17. 78 FR 44112 - California State Motor Vehicle Pollution Control Standards; Urban Buses; Request for Waiver of...

    Science.gov (United States)

    2013-07-23

    ... AGENCY California State Motor Vehicle Pollution Control Standards; Urban Buses; Request for Waiver of... for emission standards and related test procedures contained in its urban bus regulations as they affect the 2002 and later model years. Urban buses are conventionally powered by a heavy-duty...

  18. School Buses & Seat Belts: A Discussion.

    Science.gov (United States)

    Alaska State Dept. of Education, Juneau.

    Safety belts are not installed in school buses for several reasons. School buses are constructed differently from automobiles in terms of (1) the locations of doors and instrument panels relative to passengers, (2) outer construction, (3) seat design and padding, and (4) visibility on the road. Under current regulations, bus seats are constructed…

  19. Battery buses and light hybrid buses in modern town traffic. Batteriebusse und Leichthybridbusse im modernen Stadtverkehr

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R. (Neoplan Gottlob Anwaerter GmbH und Co., Stuttgart (Germany))

    1993-01-01

    Apart from the manufacture of standardised line buses, Neoplan has been intensively concerned with the development of ultra-light vehicle bodies. The individual technical steps have been tested and brought from the experimental stage to readiness for mass-production by four different types of application and 10 experimental vehicles which are used in genuine daily use in traffic concerns. 1. Battery changing technique; 2. Diesel-electric power transmission and developing a wheel motor drive; 3. Diesel-electric power transmission with multiple energy supply (hybrid system). (orig./BWI)

  20. Interim Evaluation Results from New Flyer/Allison Hybrid Buses at King County Metro: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, K.; Eberts, E.; Eudy, L.

    2005-05-01

    This paper prepared for the 2005 American Public Transportation Association Bus & Paratransit Conference discusses NREL/DOE evaluation of hybrid electric articulated transit buses operated by King County Metro.

  1. Real-world emissions and fuel consumption of diesel buses and trucks in Macao: From on-road measurement to policy implications

    Science.gov (United States)

    Wu, Xiaomeng; Zhang, Shaojun; Wu, Ye; Li, Zhenhua; Zhou, Yu; Fu, Lixin; Hao, Jiming

    2015-11-01

    A total of 13 diesel buses and 12 diesel trucks in Macao were tested using portable emission measurement systems (PEMS) including a SEMTECH-DS for gaseous emissions and a SEMTECH-PPMD for PM2.5. The average emission rates of gaseous pollutants and CO2 are developed with the operating mode defined by the instantaneous vehicle specific power (VSP) and vehicle speed. Both distance-based and fuel mass-based emission factors for gaseous pollutants (e.g., CO, THC and NOX) are further estimated under typical driving conditions. The average distance-based NOX emission of heavy-duty buses (HDBs) is higher than 13 g km-1. Considering the unfavorable conditions for selective reductions catalyst (SCR) systems, such as low-speed driving conditions, more effective technology options (e.g., dedicated natural gas buses and electric buses) should be considered by policy makers in Macao. We identified strong effects of the vehicle size, engine displacement and driving conditions on real-world CO2 emission factors and fuel consumption for diesel vehicles. Therefore, detailed profiles regarding vehicle specifications can reduce the uncertainty in their fleet-average on-road fuel consumption. In addition, strong correlations between relative emission factors and driving conditions indicated by the average speed of generated micro-trips are identified based on a micro-trip method. For example, distance-based emission factors of HDBs will increase by 39% for CO, 29% for THC, 43% for NOX and 26% for CO2 when the average speed decreases from 30 km h-1 to 20 km h-1. The mitigation of on-road emissions from diesel buses and trucks by improving traffic conditions through effective traffic and economic management measures is therefore required. This study demonstrates the important role of PEMS in understanding vehicle emissions and mitigation strategies from science to policy perspectives.

  2. Particle and gaseous emissions from compressed natural gas and ultralow sulphur diesel-fuelled buses at four steady engine loads.

    Science.gov (United States)

    Jayaratne, E R; Ristovski, Z D; Meyer, N; Morawska, L

    2009-04-01

    Exhaust emissions from thirteen compressed natural gas (CNG) and nine ultralow sulphur diesel in-service transport buses were monitored on a chassis dynamometer. Measurements were carried out at idle and at three steady engine loads of 25%, 50% and 100% of maximum power at a fixed speed of 60 km h(-1). Emission factors were estimated for particle mass and number, carbon dioxide and oxides of nitrogen for two types of CNG buses (Scania and MAN, compatible with Euro 2 and 3 emission standards, respectively) and two types of diesel buses (Volvo Pre-Euro/Euro1 and Mercedez OC500 Euro3). All emission factors increased with load. The median particle mass emission factor for the CNG buses was less than 1% of that from the diesel buses at all loads. However, the particle number emission factors did not show a statistically significant difference between buses operating on the two types of fuel. In this paper, for the very first time, particle number emission factors are presented at four steady state engine loads for CNG buses. Median values ranged from the order of 10(12) particles min(-)(1) at idle to 10(15) particles km(-)(1) at full power. Most of the particles observed in the CNG emissions were in the nanoparticle size range and likely to be composed of volatile organic compounds The CO2 emission factors were about 20% to 30% greater for the diesel buses over the CNG buses, while the oxides of nitrogen emission factors did not show any difference due to the large variation between buses.

  3. The Aerodynamics of Heavy Vehicles III : Trucks, Buses and Trains

    CERN Document Server

    Orellano, Alexander

    2016-01-01

    This volume contains papers presented at the International conference “The Aerodynamics of Heavy Vehicles III: Trucks, Buses and Trains” held in Potsdam, Germany, September 12-17, 2010 by Engineering Conferences International (ECI). Leading scientists and engineers from industry, universities and research laboratories, including truck and high-speed train manufacturers and operators were brought together to discuss computer simulation and experimental techniques to be applied for the design of more efficient trucks, buses and high-speed trains in the future.   This conference was the third in the series after Monterey-Pacific Groove in 2002 and Lake Tahoe in 2007.  The presentations address different aspects of train aerodynamics (cross wind effects, underbody flow, tunnel aerodynamics and aeroacoustics, experimental techniques), truck aerodynamics (drag reduction, flow control, experimental and computational techniques) as well as computational fluid dynamics and bluff body, wake and jet flows.

  4. Clean School Bus USA: Tomorrow's Buses for Today's Children

    Science.gov (United States)

    US Environmental Protection Agency, 2010

    2010-01-01

    The U.S. Environmental Protection Agency (EPA) is ensuring that all new buses meet tighter standards developed to reduce diesel emissions and improve safety. Today's new buses are cleaner--60 times cleaner than buses built before 1990--and feature additional emergency exits, improved mirror systems, and pedestrian safety devices. But replacing…

  5. Seat Belts on School Buses: Some Considerations.

    Science.gov (United States)

    Soule, David

    1982-01-01

    A representative of the National Highway Traffic Safety Administration weighs advantages and discusses issues associated with installing seat belts in school buses. Federal regulations and research findings are considered. A list of guideline questions for school districts planning to install seat belts is included. (PP)

  6. A Busing Program for Child Patients.

    Science.gov (United States)

    Richardson, Alan S.; Hung, John T.

    1991-01-01

    The University of British Columbia (Canada) dental school has implemented a clinical experience program in which children in grades 2-4 are bused to the university for dental treatment. The program has helped maintain undergraduate pediatric dental experiences, benefited the children's dental health, and cost parents less than traditional dental…

  7. Chemical and toxicological properties of emissions from CNG transit buses equipped with three-way catalysts compared to lean-burn engines and oxidation catalyst technologies

    Science.gov (United States)

    Yoon, Seungju; Hu, Shaohua; Kado, Norman Y.; Thiruvengadam, Arvind; Collins, John F.; Gautam, Mridul; Herner, Jorn D.; Ayala, Alberto

    2014-02-01

    Chemical and toxicological properties of emissions from compressed natural gas (CNG) fueled transit buses with stoichiometric combustion engines and three-way catalyst (TWC) exhaust control systems were measured using a chassis dynamometer testing facility and compared to the data from earlier CNG engine and exhaust control technologies. Gaseous and particulate matter emissions from buses with stoichiometric engines and TWC were significantly lower than the emissions from buses with lean-burn engines. Carbonyls and volatile organic compounds (VOCs) from buses with stoichiometric engines and TWC were lower by more than 99% compared to buses with lean-burn engines. Elemental and organic carbons (EC and OC), polycyclic aromatic hydrocarbons (PAHs), and trace elements from buses with stoichiometric engines and TWC were effectively controlled and significantly lower than the emissions from buses with lean-burn engines. Potential mutagenicity measured using a microsuspension modification of the Salmonella/microsome assay was lower by more than 99% for buses with stoichiometric engines and TWC, compared to buses with lean-burn engines and OxC.

  8. Exposure to volatile organic compounds (VOC) in public buses of Pamplona, Northern Spain.

    Science.gov (United States)

    Parra, M A; Elustondo, D; Bermejo, R; Santamaría, J M

    2008-10-01

    This study examines the exposure level of passengers and drivers to VOC in public buses in a medium-size metropolitan area (Northern Spain). In-vehicle monitoring was performed on different routes, on peak and non-peak hours, during January and February 2007. A total of 112 air samples were collected onto adsorbent tubes and analysed by thermal desorption (TD) and gas chromatography/mass selective detector (GC/MSD) technique. Statistical differences were found among route to route concentrations, with those routes with major prevalence in the commercial area of the city displaying higher values; differences between peak and non-peak hours were also observed. A decrease in VOC concentrations was also registered during the weekend. BTEX ratios were estimated and found to be related to traffic emissions and similar for all the surveyed routes. Correlations confirmed traffic as the main emission source for BTEX and trimethylbenzene, their concentrations being highly associated to changes in meteorological conditions.

  9. Fuel Cell Buses in U.S. Transit Fleets: Current Status 2011

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, L.; Chandler, K.; Gikakis, C.

    2011-11-01

    This status report, fifth in a series of annual status reports from the U.S. Department of Energy's National Renewable Energy Laboratory (NREL), discusses the achievements and challenges of fuel cell propulsion for transit and summarizes the introduction of fuel cell transit buses in the United States. Progress this year includes an increase in the number of fuel cell electric buses (FCEBs), from 15 to 25, operating at eight transit agencies, as well as increased diversity of the fuel cell design options for transit buses. The report also provides an analysis of the combined results from fuel cell transit bus demonstrations evaluated by NREL with a focus on the most recent data through July 2011 including fuel cell power system reliability and durability; fuel economy; roadcall; and hydrogen fueling results. These evaluations cover 22 of the 25 FCEBs currently operating.

  10. COMPARATIVE STUDY ON EXHAUST EMISSIONS FROM DIESEL- AND CNG-POWERED URBAN BUSES

    Energy Technology Data Exchange (ETDEWEB)

    COROLLER, P; PLASSAT, G

    2003-08-24

    Couple years ago, ADEME engaged programs dedicated to the urban buses exhaust emissions studies. The measures associated with the reduction of atmospheric and noise pollution has particular importance in the sector of urban buses. In many cases, they illustrate the city's environmental image and contribute to reinforcing the attractiveness of public transport. France's fleet in service, presently put at about 14,000 units, consumes about 2 per cent of the total energy of city transport. It causes about 2 per cent of the HC emissions and from 4 to 6 per cent of the NOx emissions and particles. These vehicles typically have a long life span (about 15 years) and are relatively expensive to buy, about 150.000 euros per unit. Several technical solutions were evaluated to quantify, on a real condition cycle for buses, on one hand pollutants emissions, fuel consumption and on the other hand reliability, cost in real existing fleet. This paper presents main preliminary results on urban buses exhaust emission on two different cases: - existing Diesel buses, with fuel modifications (Diesel with low sulphur content), Diesel with water emulsion and bio-Diesel (30% oil ester in standard Diesel fuel); renovating CNG powered Euro II buses fleet, over representative driving cycles, set up by ADEME and partners. On these cycles, pollutants (regulated and unregulated) were measured as well as fuel consumption, at the beginning of a program and one year after to quantify reliability and increase/decrease of pollutants emissions. At the same time, some after-treatment technologies were tested under real conditions and several vehicles. Information such as fuel consumption, lubricant analysis, problem on the technology were following during a one year program. On the overall level, it is the combination of various action, pollution-reduction and renewal that will make it possible to meet the technological challenge of reducing emissions and fuel consumption by urban bus

  11. How Busing Burdened Blacks: Critical Race Theory and Busing for Desegregation in Nashville-Davidson County

    Science.gov (United States)

    Woodward, Jennifer R.

    2011-01-01

    This article uses critical race theory, court opinions, newspapers, and interviews to explain how the burden of busing for desegregation was placed upon Blacks in Nashville, Tennessee and why the agenda of the litigants in the Kelley v. Metropolitan Board of Education cases shifted over time. The deliberate pace of the initial desegregation…

  12. Communication Buses and Protocols for Sensor Networks

    Directory of Open Access Journals (Sweden)

    Andrew Mason

    2002-07-01

    Full Text Available This paper overviews existing digital communication buses which are commonly used in sensor networks, discusses sensor network architectures, and introduces a new sensor bus for low power microsystem applications. The new intra-module multi-element microsystem (IM2 bus is nine-line interface with 8b serial data which implements several advanced features such as power management and plug-n-play while maintaining minimum hardware overhead at the sensor node. Finally, some issues in wireless sensor networking are discussed. The coverage of these issues provides a guideline for choosing the appropriate bus for different sensor network applications.

  13. Alameda-Contra Costa Transit District (AC Transit) Fuel Cell Transit Buses: Preliminary Evaluation Results

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, K.; Eudy, L.

    2007-03-01

    This report provides an evaluation of three prototype fuel cell-powered transit buses operating at AC Transit in Oakland, California, and six baseline diesel buses similar in design to the fuel cell buses.

  14. 46 CFR 111.30-19 - Buses and wiring.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Buses and wiring. 111.30-19 Section 111.30-19 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Switchboards § 111.30-19 Buses and wiring. (a) General. Each bus must meet the requirements...

  15. Dynamic Extra Buses Scheduling Strategy in Public Transport

    Directory of Open Access Journals (Sweden)

    Bin Yu

    2015-06-01

    Full Text Available This paper presents a dynamic extra buses scheduling strategy to improve the transit service of transit routes. In this strategy, in order to decide when to dispatch an extra bus, the service reliability of transit route is assessed firstly. A model aimed at maximizing the benefit of the extra buses scheduling strategy is constructed to determine how many stops extra buses need to skip from the terminal to accommodate passengers at the following stops. A heuristic algorithm is defined and implemented to estimate the service reliability of transit route and to optimize the initial stop of extra buses scheduling strategy. Finally, the strategy is tested on two examples: a simple and a real-life transit route in the Dalian city in China. The results show that the extra buses scheduling strategy based on terminal stops with a reasonable threshold can save 8.01% waiting time of passengers.

  16. Control of transcription by cell size.

    Directory of Open Access Journals (Sweden)

    Chia-Yung Wu

    Full Text Available Cell size increases significantly with increasing ploidy. Differences in cell size and ploidy are associated with alterations in gene expression, although no direct connection has been made between cell size and transcription. Here we show that ploidy-associated changes in gene expression reflect transcriptional adjustment to a larger cell size, implicating cellular geometry as a key parameter in gene regulation. Using RNA-seq, we identified genes whose expression was altered in a tetraploid as compared with the isogenic haploid. A significant fraction of these genes encode cell surface proteins, suggesting an effect of the enlarged cell size on the differential regulation of these genes. To test this hypothesis, we examined expression of these genes in haploid mutants that also produce enlarged size. Surprisingly, many genes differentially regulated in the tetraploid are identically regulated in the enlarged haploids, and the magnitude of change in gene expression correlates with the degree of size enlargement. These results indicate a causal relationship between cell size and transcription, with a size-sensing mechanism that alters transcription in response to size. The genes responding to cell size are enriched for those regulated by two mitogen-activated protein kinase pathways, and components in those pathways were found to mediate size-dependent gene regulation. Transcriptional adjustment to enlarged cell size could underlie other cellular changes associated with polyploidy. The causal relationship between cell size and transcription suggests that cell size homeostasis serves a regulatory role in transcriptome maintenance.

  17. 76 FR 77888 - Student Transportation of America, Inc.-Control-Dairyland Buses, Inc.

    Science.gov (United States)

    2011-12-14

    ... Surface Transportation Board Student Transportation of America, Inc.--Control--Dairyland Buses, Inc... Transaction. SUMMARY: Student Transportation of America, Inc., a motor carrier of passengers (Student... 1182.8. DATES: Comments must be filed by January 27, 2012. Student Transportation may file a reply...

  18. Solar array deployment qualification for the LMX of buses

    Science.gov (United States)

    Lee, Kathy

    2005-07-01

    The solar array deployment system for the LMX line of buses deploys rigid Solar Array Wing Assemblies (SAWAs). Each SAWA has a set of Solar Array Deployment Mechanisms (SADM), which consists of two hinges, a strut, and two Hold Down Release Mechanisms (HDRMs). To qualify the SADM for flight, each mechanism component was qualified individually, then assembled to a qualification SAWA on Special Test Equipment (STE) and deployed in a thermal vacuum chamber at ambient, hot, and cold temperatures. These mechanisms were designed, built, and tested by the Power and Mechanisms part of the Power, Thermal, Structures & Mechanisms Product Center, which develops products for both internal and external customers. This paper will discuss the qualification effort for the LMX Solar Array deployment, including qualification hardware and STE. It will focus on unique challenges presented by each aspect of the qualification, and lessons learned from the hardware integration and the qualification testing.

  19. [Energy Conservation and Emissions Reduction Benefits Analysis for Battery Electric Buses Based on Travel Services].

    Science.gov (United States)

    Lin, Xiao-dan; Tian, Liang; Lü, Bin; Yang, Jian-xin

    2015-09-01

    Battery Electric Bus (BEB) has become one of prior options of urban buses for its "zero emission" during the driving stage. However, the environmental performance of electric buses is affected by multi-factors from the point of whole life cycle. In practice, carrying capacity of BEB and power generation structures can both implement evident effects on the energy consumption and pollutants emission of BEB. Therefore, take the above factors into consideration, in this article, Life Cycle Assessment is employed to evaluate the energy conservation and emissions reduction benefits of BEB. Results indicate that, travel service is more reasonable as the functional unit, rather than mileage, since the carrying capacity of BEB is 15% lower than the diesel buses. Moreover, compared with diesel buses, the energy conservation and emissions reduction benefits of battery electric buses are all different due to different regional power structures. Specifically, the energy benefits are 7. 84%, 11. 91%, 26. 90%, 11. 15%, 19. 55% and 20. 31% respectively in Huabei, Huadong, Huazhong, Dongbei, Xibei and Nanfang power structure. From the point of comprehensive emissions reduction benefits, there is no benefit in Huabei power structure, as it depends heavily on coal. But in other areas, the comprehensive emissions reduction benefits of BEB are separately 3. 46%, 26. 81%, 1. 17%, 13. 74% and 17. 48% in Huadong, Huazhong, Dongbei, Xibei and Nanfang. Therefore, it suggests that, enlargement of carrying capacity should be taken as the most prior technology innovation direction for BEB, and the grids power structure should be taken into consideration when the development of BEB is in planning.

  20. Quality assurance program guidelines for application to and use by manufacturers of rail/guideway vehicles, buses, automatic train control systems, and their major subsystems

    Science.gov (United States)

    Witkin, S. A.

    1976-01-01

    Guidelines are presented for a quality assurance system to be implemented by the manufacturer in support of designing, developing, fabricating, assembling, inspecting, testing, handling, and delivery of equipment being procured for use in public urban mass transit systems. The guidelines apply to this equipment when being procured for: (1) use in revenue service; (2) demonstration of systems that will be revenue producing or used by the public; (3) use as a prototype for follow-on operational/revenue producing equipment procurements; and (4) qualification tests.

  1. King County Metro Transit Hybrid Articulated Buses: Final Evaluation Results

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, K.; Walkowicz, K.

    2006-12-01

    Final technical report compares and evaluates new diesel and diesel hybrid-electric articulated buses operated as part of the King County Metro Transit (KC Metro) fleet in Seattle, Washington. The evaluation lasted 12 months.

  2. Comparative study of the work load between one-man buses and two-man buses.

    Directory of Open Access Journals (Sweden)

    Ueno,Mitsuo

    1985-06-01

    Full Text Available The differences in physiological and safety conditions of one-man buses and two-man buses were examined from the view point of occupational fatigue. This survey consisted of a work load study which included a time study, study of subsidiary behavior, auditory task, memory test, Galvanic Skin Response (GSR and physiological function tests and a self-administered questionnaire which involved items concerning safety and subjective fatigue complaints. The visual and postural restrictions in the one-man bus were greater than in the two-man bus. The mental capacity of the one-man bus drivers was found to be less. Greater mental fatigue and stress were observed in the one-man bus. More subjective fatigue complaints were observed in the one-man bus. More cases of near accidents were observed in the one-man bus. From these results it was concluded that the one-man bus caused bus drivers a greater mental and physical work load.

  3. Particle size characterization by ultrasonic attenuation spectra

    Institute of Scientific and Technical Information of China (English)

    Mingxu Su; Minghua Xue; Xiaoshu Cai; Zhitao Shang; Feng Xu

    2008-01-01

    This paper contributes to extracting information from signals of broadband ultrasonic attenuation spectrum for effective utilization in particle size characterization. The single particle scattering model and the coupled-phase model are formulated simultaneously, the relationship between particle size distribution and ultrasonic spectrum is established, and a convergence criterion for calculation is quantified. Demonsa'ation inversion by the optimum regularization factor method is carded out to yield typical numerical results for discussion. With the experimental set-up developed by the Institute of Particle and Two-Phase Flow Measurement (IPTFM) at the University of Shanghai for Science and Technology, sand sediment particle size is measured by attenuation spectrum and analyzed using the above inversion algorithm and theoretical models. To validate the proposed ultrasonic spectrum particle sizing method, results are compared with those obtained by microscopy.

  4. Seed size selection by olive baboons.

    Science.gov (United States)

    Kunz, Britta Kerstin; Linsenmair, Karl Eduard

    2008-10-01

    Seed size is an important plant fitness trait that can influence several steps between fruiting and the establishment of a plant's offspring. Seed size varies considerably within many plant species, yet the relevance of the trait for intra-specific fruit choice by primates has received little attention. Primates may select certain seed sizes within a species for a number of reasons, e.g. to decrease indigestible seed load or increase pulp intake per fruit. Olive baboons (Papio anubis, Cercopithecidae) are known to select seed size in unripe and mature pods of Parkia biglobosa (Mimosaceae) differentially, so that pods with small seeds, and an intermediate seed number, contribute most to dispersal by baboons. We tested whether olive baboons likewise select for smaller ripe seeds within each of nine additional fruit species whose fruit pulp baboons commonly consume, and for larger seeds in one species in which baboons feed on the seeds. Species differed in fruit type and seed number per fruit. For five of these species, baboons dispersed seeds that were significantly smaller than seeds extracted manually from randomly collected fresh fruits. In contrast, for three species, baboons swallowed seeds that were significantly longer and/or wider than seeds from fresh fruits. In two species, sizes of ingested seeds and seeds from fresh fruits did not differ significantly. Baboons frequently spat out seeds of Drypetes floribunda (Euphorbiaceae) but not those of other plant species having seeds of equal size. Oral processing of D. floribunda seeds depended on seed size: seeds that were spat out were significantly larger and swallowed seeds smaller, than seeds from randomly collected fresh fruits. We argue that seed size selection in baboons is influenced, among other traits, by the amount of pulp rewarded per fruit relative to seed load, which is likely to vary with fruit and seed shape.

  5. Gaseous emissions from compressed natural gas buses in urban road and highway tests in China.

    Science.gov (United States)

    Yue, Tingting; Chai, Fahe; Hu, Jingnan; Jia, Ming; Bao, Xiaofeng; Li, Zhenhua; He, Liqang; Zu, Lei

    2016-10-01

    The natural gas vehicle market is rapidly developing throughout the world, and the majority of such vehicles operate on compressed natural gas (CNG). However, most studies on the emission characteristics of CNG vehicles rely on laboratory chassis dynamometer measurements, which do not accurately represent actual road driving conditions. To further investigate the emission characteristics of CNG vehicles, two CNG city buses and two CNG coaches were tested on public urban roads and highway sections. Our results show that when speeds of 0-10km/hr were increased to 10-20km/hr, the CO2, CO, nitrogen oxide (NOx), and total hydrocarbon (THC) emission factors decreased by (71.6±4.3)%, (65.6±9.5)%, (64.9±9.2)% and (67.8±0.3)%, respectively. In this study, The Beijing city buses with stricter emission standards (Euro IV) did not have lower emission factors than the Chongqing coaches with Euro II emission standards. Both the higher emission factors at 0-10km/hr speeds and the higher percentage of driving in the low-speed regime during the entire road cycle may have contributed to the higher CO2 and CO emission factors of these city buses. Additionally, compared with the emission factors produced in the urban road tests, the CO emission factors of the CNG buses in highway tests decreased the most (by 83.2%), followed by the THC emission factors, which decreased by 67.1%.

  6. RELIABILITY OF BRAKE SYSTEMS OF BUSES OF GROUP MAZ

    Directory of Open Access Journals (Sweden)

    A. Bessarab

    2013-01-01

    Full Text Available All over the world safety of maintained vehicles has the major value. For motor vehicles of the Republic of Belarus this problem is also actual. Maintenance of high reliability of brake systems of cars in operation is one of ways of the decision of a problem of increase of traffic safety.The analysis of reliability of brake systems of buses MAZ is carried out following the results of the state maintenance service in 2010 and the analysis of premature returns from routes of movement of buses MAZ-103 and МАZ-104 one of the motor transportation enterprises of a city of Minsk. Principal causes of structural parameters modification of brake pneumatic system of buses, the brake mechanism and elements АBS are considered.

  7. Reliability Evaluation Of The City Transport Buses Under Actual Conditions

    Directory of Open Access Journals (Sweden)

    Rymarz Joanna

    2015-12-01

    Full Text Available The purpose of this paper was to present a reliability comparison of two types of city transport buses. Case study on the example of the well-known brands of city buses: Solaris Urbino 12 and Mercedes-Benz 628 Conecto L used at Municipal Transport Company in Lublin was presented in details. A reliability index for the most failure parts and complex systems for the period of time failures was determined. The analysis covered damages of the following systems: engine, electrical system, pneumatic system, brake system, driving system, central heating and air-conditioning and doors. Reliability was analyzed based on Weibull model. It has been demonstrated, that during the operation significant reliability differences occur between the buses produced nowadays.

  8. Optimum Network Reconfiguration and DGs Sizing With Allocation Simultaneously by Using Particle Swarm Optimization (PSO

    Directory of Open Access Journals (Sweden)

    M. N. M. Nasir

    2014-05-01

    Full Text Available This paper presents three stages of methodology. The first stage is to identify the switching operation for radial network configuration while observe the power losses and the voltage profile without Distributed Generation (DG. The second stage is based on previous paper which is feeder reconfiguration for loss reduction with DGs. The last stage is sizing and allocation DGs at buses with low voltage profile resulted from the first stage to improve the power losses and voltage profile also comparing the result with the second stage. The objective of this method proposed is to show that allocation of DGs simultaneously based on low voltage profile can improve network power losses and improvement of voltage profile. The result shows that improvement on network power losses is 54.92% from Distribution Network Reconfiguration (DNR method. All three stages were tested on standards IEEE 33 bus system by using Particle Swarm Optimization (PSO technique in MATLAB software. This method proved that improvement of power losses and voltage profile by switching and DGs allocation method.

  9. RELIABILITY OF BRAKE SYSTEMS OF BUSES OF GROUP MAZ

    OpenAIRE

    A. Bessarab

    2013-01-01

    All over the world safety of maintained vehicles has the major value. For motor vehicles of the Republic of Belarus this problem is also actual. Maintenance of high reliability of brake systems of cars in operation is one of ways of the decision of a problem of increase of traffic safety.The analysis of reliability of brake systems of buses MAZ is carried out following the results of the state maintenance service in 2010 and the analysis of premature returns from routes of movement of buses M...

  10. Intermediate transport in Southeast Asia. [Carts, cycles, mini-buses

    Energy Technology Data Exchange (ETDEWEB)

    Meier, A.K.

    1977-06-01

    Traffic flows through the streets of Southeast Asian countries even though they are used for almost all aspects of human and animal existence. The carts, bicycles, tricycles, and motorcycles, motorized three-wheelers, mini-buses are the so-called intermediate-transport vehicles. It is upon this group of vehicles that a culture--constrained by its own unique economic, environmental, and technological factors--exerts its influence most directly toward the solution of the transport problem. Transportation fills more service roles in Southeast Asian cities than in Western cities. Communication facilities such as telephones and postal services are notoriously unreliable. The personal encounter is all important in social and business interactions in Southeast Asia. Each of the transport modes is examined in view of design and use in a number of specific cultural settings for the countries in Southeast Asia. Present use of intermediate transport in developed countries is discussed briefly, and its further development predicted--pointing out the health and conservation advantages. (MCW)

  11. 2D Metals by Repeated Size Reduction.

    Science.gov (United States)

    Liu, Hanwen; Tang, Hao; Fang, Minghao; Si, Wenjie; Zhang, Qinghua; Huang, Zhaohui; Gu, Lin; Pan, Wei; Yao, Jie; Nan, Cewen; Wu, Hui

    2016-10-01

    A general and convenient strategy for manufacturing freestanding metal nanolayers is developed on large scale. By the simple process of repeatedly folding and calendering stacked metal sheets followed by chemical etching, free-standing 2D metal (e.g., Ag, Au, Fe, Cu, and Ni) nanosheets are obtained with thicknesses as small as 1 nm and with sizes of the order of several micrometers.

  12. Life Cycle Assessment of Diesel and Electric Public Transportation Buses

    Science.gov (United States)

    The Clean Air Act identifies diesel powered motor vehicles, including transit buses, as significant sources of several criteria pollutants which contribute to ground level ozone formation or smog. The effects of air pollution in urban areas are often more significant due to con...

  13. No Breathing in the Aisles: Diesel Exhaust inside School Buses.

    Science.gov (United States)

    Solomon, Gina M.; Campbell, Todd R.; Feuer, Gail Ruderman; Masters, Julie; Samkian, Artineh; Paul, Kavita Ann

    There is evidence that diesel exhaust causes cancer and premature death, and also exacerbates asthma and other respiratory illness. Noting that the vast majority of the nation's school buses run on diesel fuel, this report details a study examining the level of diesel exhaust to which children are typically exposed as they travel to and from…

  14. Cost Effectiveness Analysis of Quasi-In-Motion Wireless Power Transfer for Plug-In Hybrid Electric Transit Buses from Fleet Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijuan; Gonder, Jeff; Brooker, Aaron; Meintz, Andrew; Konan, Arnaud; Markel, Tony

    2016-05-16

    This study evaluated the costs and benefits associated with the use of stationary-wireless-power-transfer-enabled plug-in hybrid electric buses and determined the cost effectiveness relative to conventional buses and hybrid electric buses. A factorial design was performed over a number of different battery sizes, charging power levels, and f bus stop charging stations. The net present costs were calculated for each vehicle design and provided the basis for design evaluation. In all cases, given the assumed economic conditions, the conventional bus achieved the lowest net present cost while the optimal plug-in hybrid electric bus scenario beat out the hybrid electric comparison scenario. The parameter sensitivity was also investigated under favorable and unfavorable market penetration assumptions.

  15. Evolved star water maser cloud size determined by star size

    CERN Document Server

    Richards, A M S; Gray, M D; Lekht, E E; Mendoza-Torres, J E; Murakawa, K; Rudnitskij, G; Yates, J A

    2012-01-01

    Cool, evolved stars undergo copious mass loss but the details of how the matter is returned to the ISM are still under debate. We investigated the structure and evolution of the wind at 5 to 50 stellar radii from Asymptotic Giant Branch and Red Supergiant stars. 22-GHz water masers around seven evolved stars were imaged using MERLIN, at sub-AU resolution. Each source was observed at between 2 and 7 epochs (several stellar periods). We compared our results with long-term Pushchino single dish monitoring. The 22-GHz emission is located in ~spherical, thick, unevenly filled shells. The outflow velocity doubles between the inner and outer shell limits. Water maser clumps could be matched at successive epochs separated by <2 years for AGB stars, or at least 5 years for RSG. This is much shorter than the decades taken for the wind to cross the maser shell, and comparison with spectral monitoring shows that some features fade and reappear. In 5 sources, most of the matched features brighten or dim in concert from...

  16. Large size metallic glass gratings by embossing

    Science.gov (United States)

    Ma, J.; Yi, J.; Zhao, D. Q.; Pan, M. X.; Wang, W. H.

    2012-09-01

    Bulk metallic glasses have excellent thermoforming ability in their wide supercooled liquid region. We show that large-size metallic glass grating (˜8 × 8 mm2) with fine periodicity and ultra smooth surface feature can be readily fabricated by hot embossing. The method for fabrication of gratings is proved to be much cheaper, and requires low pressure and short time (less than 30 s). The metallic glass gratings exhibit comparable optical properties such as rainbow-like spectrum when shone by fluorescent lamp light.

  17. Evaluating real-world CO2 and NOX emissions for public transit buses using a remote wireless on-board diagnostic (OBD) approach.

    Science.gov (United States)

    Yang, Liuhanzi; Zhang, Shaojun; Wu, Ye; Chen, Qizheng; Niu, Tianlin; Huang, Xu; Zhang, Shida; Zhang, Liangjun; Zhou, Yu; Hao, Jiming

    2016-11-01

    The challenge to mitigate real-world emissions from vehicles calls for powerful in-use compliance supervision. The remote on-board diagnostic (OBD) approach, with wireless data communications, is one of the promising next-generation monitoring methods. We collected second-by-second profiles of carbon dioxide (CO2) and nitrogen oxides (NOX) emissions, driving conditions and engine performance for three conventional diesel and three hybrid diesel buses participating in a remote OBD pilot program in Nanjing, China. Our results showed that the average CO2 emissions for conventional diesel and hybrid diesel buses were 816 ± 83 g km(-1) and 627 ± 54 g km(-1), respectively, under a typical driving pattern. An operating mode binning analysis indicated that CO2 emissions reduction by series-parallel hybrid technology was largely because of the significant benefits of the technology under the modes of low speed and low power demand. However, significantly higher CO2 emissions were observed for conventional diesel buses during rush hours, higher than 1200 g km(-1). The OBD data suggested no improvement in NOX emission reduction for hybrid buses compared with conventional buses; both were approximately 12 g km(-1) because of poor performance of the selective catalyst reduction (SCR) systems in the real world. Speed-dependent functions for real-world CO2 and NOX emissions were also constructed. The CO2 emissions of hybrid buses were much less sensitive to the average speed than conventional buses. If the average speed decreased from 20 km h(-1) to 10 km h(-1), the estimated CO2 emission factor for conventional buses would be increased by 34%. Such a change in speed would increase NOX emissions for conventional and hybrid buses by 38% and 56%, respectively. This paper demonstrates the useful features of the remote OBD system and can inform policy makers how to take advantage of these features in monitoring in-use vehicles.

  18. The Fuel Economy of Hybrid Buses: The Role of Ancillaries in Real Urban Driving

    Directory of Open Access Journals (Sweden)

    Francesco Bottiglione

    2014-07-01

    Full Text Available In the present context of the global economic crisis and environmental emergency, transport science is asked to find innovative solutions to turn traditional vehicles into fuel-saving and eco-friendly devices. In the last few years, hybrid vehicles have been shown to have potential benefits in this sense. In this paper, the fuel economy of series hybrid-electric and hybrid-mechanical buses is simulated in two real driving situations: cold and hot weather driving in the city of Taranto, in Southern Italy. The numerical analysis is carried out by an inverse dynamic approach, where the bus speed is given as a velocity pattern measured in the field tests performed on one of the city bus routes. The city of Taranto drive schedule is simulated in a typical tempered climate condition and with a hot temperature, when the air conditioning system must be switched on for passenger comfort. The fuel consumptions of hybrid-electric and hybrid-mechanical buses are compared to each other and with a traditional bus powered by a diesel engine. It is shown that the series hybrid-electric vehicle outperforms both the traditional and the mechanical hybrid vehicles in the cold weather driving simulation, reducing the fuel consumption by about 35% with respect to the traditional diesel bus. However, it is also shown that the performance of the hybrid-electric bus gets dramatically worse when the air-cooling system is continuously turned on. In this situation, the fuel consumption of the three different technologies for city buses under investigation is comparable.

  19. Characteristics of cabin air quality in school buses in Central Texas

    Science.gov (United States)

    Rim, Donghyun; Siegel, Jeffrey; Spinhirne, Jarett; Webb, Alba; McDonald-Buller, Elena

    This study assessed in-cabin concentrations of diesel-associated air pollutants in six school buses with diesel engines during a typical route in suburban Austin, Texas. Air exchange rates measured by SF 6 decay were 2.60-4.55 h -1. In-cabin concentrations of all pollutants measured exhibited substantial variability across the range of tests even between buses of similar age, mileage, and engine type. In-cabin NO x concentrations ranged from 44.7 to 148 ppb and were 1.3-10 times higher than roadway NO x concentrations. Mean in-cabin PM 2.5 concentrations were 7-20 μg m -3 and were generally lower than roadway levels. In-cabin concentrations exhibited higher variability during cruising mode than frequent stops. Mean in-cabin ultrafine PM number concentrations were 6100-32,000 particles cm -3 and were generally lower than roadway levels. Comparison of median concentrations indicated that in-cabin ultrafine PM number concentrations were higher than or approximately the same as the roadway concentrations, which implied that, by excluding the bias caused by local traffic, ultrafine PM levels were higher in the bus cabin than outside of the bus. Cabin pollutant concentrations on three buses were measured prior to and following the phased installation of a Donaldson Spiracle Crankcase Filtration System and a Diesel Oxidation Catalyst. Following installation of the Spiracle, the Diesel Oxidation Catalyst provided negligible or small additional reductions of in-cabin pollutant levels. In-cabin concentration decreases with the Spiracle alone ranged from 24 to 37% for NO x and 26 to 62% and 6.6 to 43% for PM 2.5 and ultrafine PM, respectively. Comparison of the ranges of PM 2.5 and ultrafine PM variations between repetitive tests suggested that retrofit installation could not always be conclusively linked to the decrease of pollutant levels in the bus cabin.

  20. Operational integrity using field buses; Integridade operacional utilizando barramentos de campo

    Energy Technology Data Exchange (ETDEWEB)

    Hennig, Carlos Henrique [Coester Automacao S.A., Sao Leopoldo, RS (Brazil)

    2004-07-01

    The device information is collected using standardized Filed Buses with high data transmission capacity, which allows the analysis of his operational status in real time. The quantity of information generated by the devices for the maintenance area is increasing and this data quantity transferred through the field bus should not interfere in the network performance to the point of degrade his control function. In this way, is presented a technique that can be used in different protocols, which allow sending of maintenance data using a small band of the communication channel. Operational integrity can be achieved using predictive maintenance techniques based on the collected data. (author)

  1. Analysis of the cost of hydrogen infrastructure for buses in London

    Science.gov (United States)

    Shayegan, S.; Hart, D.; Pearson, P.; Joffe, D.

    The use of hydrogen (H 2) as transport fuel is often said to suffer from the 'chicken and egg' problem: vehicles that depend on H 2 cannot go on the roads due to the lack of an adequate infrastructure, and the almost non-existent fleet of H 2 vehicles on the roads makes it economically unsound to build a H 2 infrastructure. Although both hydrogen vehicles (fuel cell and internal combustion engine) and the related infrastructure have been (and are being) developed and some are commercially available, cost is seen as a major barrier. With today's technologies, H 2 only becomes competitive with petrol and diesel when produced at large quantities, suitable for supplying e.g. thousands of H 2 buses. The question is, how might this point be reached, and are there least cost infrastructural pathways to reach it. This paper tries to address the latter question, using the early development of a H 2 infrastructure for buses in London as a case study. The paper presents some of the analyses and results from a Ph.D. project (in progress) being undertaken at Imperial College London, funded by EPSRC (Grant GR/R50790/01). The results presented here illustrate that cost of hydrogen production and delivery vary mainly with levels of hydrogen demand and delivery distances, as well as other logistic criteria; least cost production-delivery pathways have been identified for various hydrogen demand scenarios and refuelling station set-ups. Another important conclusion is that the pattern of converting a group of refuelling stations to hydrogen (e.g. a group of refuelling stations for buses in London) has a significant effect on the unit cost of hydrogen.

  2. To Evaluate Zero Emission Propulsion and Support Technology for Transit Buses

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Chandler; Leslie Eudy

    2006-11-01

    This report provides evaluation results for prototype fuel cell transit buses operating at Santa Clara Valley Transportation Authority (VTA) in San Jose, California, in partnership with the San Mateo County Transit District in San Carlos, California. VTA has been operating three fuel cell transit buses in extra revenue service since February 28, 2005. This report provides descriptions of the equipment used, early experiences, and evaluation results from the operation of the buses and the supporting hydrogen infrastructure from March 2005 through July 2006.

  3. Mechanised charging stations enable point-to-point service for battery operated buses; Mechanisierte Ladestationen eroeffnen Batteriebussen den Linienbetrieb

    Energy Technology Data Exchange (ETDEWEB)

    Eggers, S. [Gottlob Auwaerter GmbH und Co., Stuttgart (Germany)

    1994-12-31

    Buses operated by an electrical battery do not any longer have a major disadvantage: the relatively short period of use/application. By means of mobile exchange charging stations the batteries of the buses do not have to be recharged for hours at installed charging stations or to be exchanged on a rather complicated way by forklifts. The battery exchange is as easy as filling up a car tank with diesel and can be carried out by the bus-driver himself within a few minutes. (orig.) [Deutsch] Batterie-elektrisch betriebene Busse haben einen gefuerchteten Nachteil verloren: die relativ geringe Einsatzzeit. Durch die mobile Wechsel-/Ladestation muessen die Busse nunmehr nicht mehr stundenlang an fest installierten Ladestationen `nachtanken` oder dort umstaendliche Batteriewechsel mit Hilfe von Gabelstaplern in Kauf nehmen. Der Batteriewechsel ist so einfach wie das Tanken von Dieselkraftstoff und wird von dem Busfahrer sebst in wenigen Minuten vorgenommen. (orig.)

  4. Particle size reduction of propellants by cryocycling

    Energy Technology Data Exchange (ETDEWEB)

    Whinnery, L.; Griffiths, S.; Lipkin, J. [and others

    1995-05-01

    Repeated exposure of a propellant to liquid nitrogen causes thermal stress gradients within the material resulting in cracking and particle size reduction. This process is termed cryocycling. The authors conducted a feasibility study, combining experiments on both inert and live propellants with three modeling approaches. These models provided optimized cycle times, predicted ultimate particle size, and allowed crack behavior to be explored. Process safety evaluations conducted separately indicated that cryocycling does not increase the sensitivity of the propellants examined. The results of this study suggest that cryocycling is a promising technology for the demilitarization of tactical rocket motors.

  5. Purification of Nanoparticles by Size and Shape

    Science.gov (United States)

    Robertson, James D.; Rizzello, Loris; Avila-Olias, Milagros; Gaitzsch, Jens; Contini, Claudia; Magoń, Monika S.; Renshaw, Stephen A.; Battaglia, Giuseppe

    2016-06-01

    Producing monodisperse nanoparticles is essential to ensure consistency in biological experiments and to enable a smooth translation into the clinic. Purification of samples into discrete sizes and shapes may not only improve sample quality, but also provide us with the tools to understand which physical properties of nanoparticles are beneficial for a drug delivery vector. In this study, using polymersomes as a model system, we explore four techniques for purifying pre-formed nanoparticles into discrete fractions based on their size, shape or density. We show that these techniques can successfully separate polymersomes into monodisperse fractions.

  6. Fuel Cell Buses in U.S. Transit Fleets: Current Status 2015

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, Leslie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Post, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Gikakis, Christina [Federal Transit Administration, Washington, DC (United States)

    2015-12-11

    This report, published annually, summarizes the progress of fuel cell electric bus (FCEB) development in the United States and discusses the achievements and challenges of introducing fuel cell propulsion in transit. Various stakeholders, including FCEB developers, transit agencies, and system integrators, have expressed the value of this annual status report, which provides a summary of results from evaluations performed by the National Renewable Energy Laboratory. The annual status report tracks the progress of the FCEB industry toward meeting technical targets, documents the lessons learned, and discusses the path forward for commercial viability of fuel cell technology for transit buses. The 2015 summary results primarily focus on the most recent year for each demonstration, from August 2014 through July 2015. The results for these buses account for more than 1,045,000 miles traveled and 83,000 hours of fuel cell power system operation. The primary results presented in the report are from two demonstrations of fuel-cell-dominant bus designs: the Zero Emission Bay Area Demonstration Group led by Alameda-Contra Costa Transit District (AC Transit) in California and the American Fuel Cell Bus Project at SunLine Transit Agency in California.

  7. Seat Belt Usage on School Buses.

    Science.gov (United States)

    Farmer, Ernest

    1985-01-01

    Studies on seat belt usage conducted under contract with governmental organizations or prepared by professional societies, state and local organizations, and transportation specialists have made significant contributions, but none has successfully resolved the issue. (MLF)

  8. Snow, buses, and mobile data services

    DEFF Research Database (Denmark)

    Fomin, Vladislav

    2006-01-01

    and Daniel Robey [2002], in wich the authors use anecdotes to demonstrate what advanced service possibilities are afforded by ubiquitous technology as contrasted to the residue of social behavior.This story illustrates that the succes of establishing Information Society should not be measured by the number...... of available services to citizens over the wireline and mobile Internet. The ultimate measure for success must be the extent to which poeple are aware about the availability of relevant content and are using the services [Daniel and Wilson, 2003, p.285]....

  9. In-Use Fleet Evaluation of Fast-Charge Battery Electric Transit Buses

    Energy Technology Data Exchange (ETDEWEB)

    Prohaska, Robert; Kelly, Kenneth; Eudy; Leslie

    2016-06-27

    With support from the U.S. Department of Energy's Vehicle Technologies Office, the National Renewable Energy Laboratory (NREL) conducts real-world performance evaluations of advanced medium- and heavy-duty fleet vehicles. Evaluation results can help vehicle manufacturers fine-tune their designs and assist fleet managers in selecting fuel-efficient, low-emission vehicles that meet their economic and operational goals. In 2015, NREL launched an in-service evaluation of 12 battery electric buses (BEBs) compared to conventional compressed natural gas (CNG) buses operated by Foothill Transit in West Covina, California. The study aims to improve understanding of the overall usage and effectiveness of fast-charge BEBs and associated charging infrastructure in transit operation. To date, NREL researchers have analyzed more than 148,000 km of in-use operational data, including driving and charging events. Foothill Transit purchased the BEBs with grant funding from the Federal Transit Administration's Transit Investments for Greenhouse Gas and Energy Reduction Program.

  10. Buses and Boards Making the right choice

    CERN Document Server

    Gipper, Jerry

    2009-01-01

    From motherboard to backplane to blade based computer systems, the choices are numerous. This paper will cover the markets and trends within those markets that influence decisions made by board suppliers. Discussion will focus on the various form factors, the development and evolution of industry standards, and the consortia that support and develop these standards, including VITA, PICMG, and others. This paper will conclude with suggestions for choosing the right form factor for your application.

  11. Variability of particle number emissions from diesel and hybrid diesel-electric buses in real driving conditions.

    Science.gov (United States)

    Sonntag, Darrell B; Gao, H Oliver; Holmén, Britt A

    2008-08-01

    A linear mixed model was developed to quantify the variability of particle number emissions from transit buses tested in real-world driving conditions. Two conventional diesel buses and two hybrid diesel-electric buses were tested throughout 2004 under different aftertreatments, fuels, drivers, and bus routes. The mixed model controlled the confounding influence of factors inherent to on-board testing. Statistical tests showed that particle number emissions varied significantly according to the after treatment, bus route, driver, bus type, and daily temperature, with only minor variability attributable to differences between fuel types. The daily setup and operation of the sampling equipment (electrical low pressure impactor) and mini-dilution system contributed to 30-84% of the total random variability of particle measurements among tests with diesel oxidation catalysts. By controlling for the sampling day variability, the model better defined the differences in particle emissions among bus routes. In contrast, the low particle number emissions measured with diesel particle filters (decreased by over 99%) did not vary according to operating conditions or bus type but did vary substantially with ambient temperature.

  12. High Energy Batteries for Hybrid Buses

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Lu

    2010-12-31

    EnerDel technology, and helps DOE to evaluate the merits of underlying technology. The successful completion of this program demonstrated the capability of EnerDel battery packs to satisfactorily supply all power and energy requirements of a real-world HEV-Bus drive profile. This program supports green solutions to metropolitan public transportation problems by demonstrating the effectiveness of EnerDel lithium ion batteries for HEV-Bus applications.

  13. Bay Area Transit Agencies Propel Fuel Cell Buses Toward Commercialization (Fact Sheet)

    Energy Technology Data Exchange (ETDEWEB)

    2010-07-01

    This fact sheet describes the Zero Emission Bay Area (ZEBA) demonstration of the next generation of fuel cells buses. Several transit agencies in the San Francisco Bay Area are participating in demonstrating the largest single fleet of fuel cell buses in the United States.

  14. 78 FR 719 - California State Motor Vehicle Pollution Control Standards; Urban Buses; Request for Waiver of...

    Science.gov (United States)

    2013-01-04

    ... AGENCY California State Motor Vehicle Pollution Control Standards; Urban Buses; Request for Waiver of... amendments to its emission standards for urban bus engines in a series of rulemakings. The rulemakings at... public transit agencies that operate urban buses and other transit vehicles; additionally,...

  15. Using Task Clarification, Goal Setting, and Feedback to Decrease Table Busing Times in a Franchise Pizza Restaurant

    Science.gov (United States)

    Amigo, Seth; Smith, Andrew; Ludwig, Timothy

    2008-01-01

    The current study investigated the effects of task-clarification, and manager verbal and graphic feedback on employee busing times at a pizza restaurant. Using an ABC design, task-clarification was provided in a memo, which described the process, priority, and goal time of busing. The busing time decreased slightly, from an average of 315 seconds…

  16. The Busing Controversy. [NAESP] School Leadership Digest [Second Series, Number 6. ERIC/CEM Research Analysis Series, Number 21.

    Science.gov (United States)

    Schofield, Dee

    To understand the controversy over busing, it is necessary to understand the relationship between busing and the issues that are actually at the root of the controversy: desegregation and freedom of choice. Much of the political activity surrounding busing is a subtle transfer of attention away from the basic issue of desegregation. Other…

  17. Size-Dependent Melting Behaviour of Nanometre-Sized Pb Particles Studied by Dynamic Mechanical Analysis

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-Min; FEI Guang-Tao; CUI Ping

    2006-01-01

    Nanometre-sized (hereafter nano-)Pb particles embedded in an Al matrix are prepared by ball milling.It is found that the size of nano-Pb particles was decreased with increasing milling time.The melting behaviour of nano-Pb particles embedded in the Al matrix is studied by means of dynamic mechanical analysis,and a single internal friction peak in the vicinity of Pb melting temperature is observed.The onset temperature of the peak moves to lower temperature with the decrease of particles size and the internal friction peak height is increased,which indicates a size-dependent melting behaviour of nano-Pb particles.It is suggested that the size-dependent melting behaviour is associated with surface melting.

  18. Txatarra: vivienda transitoria con buses de transporte público

    Directory of Open Access Journals (Sweden)

    Juan Pablo Arenas Vargas

    2011-07-01

    Full Text Available El presente análisis del proyecto Casa Linda parte de una exploración conceptual en torno a un hábitat sostenible, mediante la generación de un tipo de vivienda transitoria que reutiliza buses de transporte público destinados a ser reducidos a chatarra. La necesidad de replantear la labor de configurar espacios con materiales y formas predeterminados llevó a los autores a comprender cómo resultan insuficientes los medios tradicionales de construcción, en los que se acostumbra emplear materias primas en presentaciones estandarizadas y con acabados predefinidos que se adaptan a los requerimientos y necesidades del proyecto. Enfrentar el proyecto a partir del reciclaje de materiales y objetos (chatarra, de diversas dimensiones y en variadas condiciones, generó un proceso cuya característica principal es la imposibilidad de anticipar con exactitud los procesos constructivos y los acabados finales.

  19. Resistojet control and power for high frequency ac buses

    Science.gov (United States)

    Gruber, Robert P.

    1987-01-01

    Resistojets are operational on many geosynchronous communication satellites which all use dc power buses. Multipropellant resistojets were selected for the Initial Operating Capability (IOC) Space Station which will supply 208 V, 20 kHz power. This paper discusses resistojet heater temperature controllers and passive power regulation methods for ac power systems. A simple passive power regulation method suitable for use with regulated sinusoidal or square wave power was designed and tested using the Space Station multipropellant resistojet. The breadboard delivered 20 kHz power to the resistojet heater. Cold start surge current limiting, a power efficiency of 95 percent, and power regulation of better than 2 percent were demonstrated with a two component, 500 W breadboard power controller having a mass of 0.6 kg.

  20. Calibrating optical bubble size by the displaced-mass method.

    NARCIS (Netherlands)

    Leifer, I.; Leeuw, G. de; Kunz, G.; Cohen, L.H.

    2003-01-01

    Bubble sizing by optical means is very common, but requires calibration by non-optical means. This is particularly important since apparent bubble size increases with decreasing threshold intensity. A calibration experiment was conducted comparing the displaced water mass from captured bubbles with

  1. Fuel Cell Buses in U.S. Transit Fleets: Current Status 2009

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, L.; Chandler, K.; Gikakis, C.

    2009-10-01

    This report documents progress in meeting the technological challenges of fuel cell propulsion for transportation based on current fuel cell transit bus demonstrations and plans for more fuel cell transit buses and hydrogen infrastructure.

  2. Report on FS survey for project of introduction of highly energy-efficient trolley buses into the Mexico Metropolitan Area in FY 1997; 1997 nendo chosa hokokusho (Mexico city eno sho energy gata trolley bus donyu project FS chosa)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Traffic jam and air pollution by automobiles are currently getting severe in the Mexico Metropolitan Area. Trolley buses were introduced for improving the environment more than ten years ago. Vehicles become too old for use, and their energy efficiency is low. In this project, 200 highly energy-efficient trolley buses are introduced to replace old inefficient trolley buses, which results in the improved traffic convenience in the City and enhanced energy efficiency. The new energy-efficient trolley buses are made of energy-efficient control VVVF inverters produced and exported by MELCO (Mitsubishi Electric Corporation), energy-efficient motors by MELMEX (Mitsubishi Electric Corporation, Mexico), and bodies by MASA which is a major manufacturer of bus bodies. The objective of this research is to analyze the background of introduction of new energy-efficient trolley buses and the effects of the present project. The results of analysis are going to be utilized for future promotion of the Joint Implementation and Clean Development Mechanism. 30 refs., 30 figs., 24 tabs.

  3. Cool Science: K-12 Climate Change Art Displayed on Buses

    Science.gov (United States)

    Chen, R. F.; Lustick, D. S.; Lohmeier, J.; Thompson, S. R.

    2015-12-01

    Cool science is an art contest where K12 students create placards (7" x 22") to educate the public about climate change. Students are prompted to create their artwork in response to questions such as: What is the evidence for climate change? How does climate change impact your local community? What can you do to reduce the impacts of climate change? In each of three years, 500-600 student entrees have been submitted from more than 12 school districts across Massachusetts. A panel of judges including scientists, artists, rapid transit representatives, and educators chooses elementary, middle, and high school winners. Winners (6), runners-up (6), and honorable mentions (12) and their families and teachers are invited to an annual Cool Science Award Ceremony to be recognized and view winning artwork. All winning artwork is posted on the Cool Science website. The winning artwork (2 per grade band) is converted into placards (11" x 28") and posters (2.5' x 12') that are placed on the inside (placards) and outside (posters) of buses. Posters are displayed for one month. So far, Cool Science was implemented in Lowell, MA where over 5000 public viewers see the posters daily on the sides of Lowell Rapid Transit Authority (LRTA) buses, making approximately 1,000,000 impressions per year. Cool Science acts to increase climate literacy in children as well as the public, and as such promotes intergenerational learning. Using art in conjunction with science learning about climate change appears to be effective at engaging not just traditionally high achieving science students, but also those interested in the creative arts. Hearing winners' stories about how they created their artwork and what this contest meant to them supports the idea that Cool Science attracts a wide diversity of students. Parents discuss climate change with their children. Multiple press releases announcing the winners further promotes the awareness of climate change throughout school districts and their

  4. CNG buses fire safety : learnings from recent accidents in France and Germany

    OpenAIRE

    Perrette, Lionel; Wiedemann, Helmut K.

    2007-01-01

    International audience; The use of CNG in bus and private vehicles is growing steadily. Recent fire accidents involving CNG buses have shown that tanks may explode though compliant with current ECE UN R110 regulation. Such a repeated scenario is certainly not acceptable having in mind the tremendous amount of energy released when a compressed tank bursts. Investigation of German and French recent cases detailed in this article highlights potential improvements in current CNG buses fire safety...

  5. In-use fuel economy of hybrid-electric school buses in Iowa.

    Science.gov (United States)

    Hallmark, Shauna; Sperry, Bob; Mudgal, Abhisek

    2011-05-01

    Although it is much safer and more fuel-efficient to transport children to school in buses than in private vehicles, school buses in the United States still consume 822 million gal of diesel fuel annually, and school transportation costs can account for a significant portion of resource-constrained school district budgets. Additionally, children in diesel-powered school buses may be exposed to higher levels of particulates and other pollutants than children in cars. One solution to emission and fuel concerns is use of hybrid-electric school buses, which have the potential to reduce emissions and overall lifecycle costs compared with conventional diesel buses. Hybrid-electric technologies are available in the passenger vehicle market as well as the transit bus market and have a track record indicating fuel economy and emissions benefits. This paper summarizes the results of an in-use fuel economy evaluation for two plug-in hybrid school buses deployed in two different school districts in Iowa. Each school district selected a control bus with a route similar to that of the hybrid bus. Odometer readings, fuel consumption, and maintenance needs were recorded for each bus. The buses were deployed in 2008 and data were collected through May 2010. Fuel consumption was calculated for each school district. In Nevada, IA, the overall average fuel economy was 8.23 mpg for the hybrid and 6.35 mpg for the control bus. In Sigourney, IA, the overall average fuel economy was 8.94 mpg for the hybrid and 6.42 mpg for the control bus. The fuel consumption data were compared for the hybrid and control buses using a Wilcoxon signed rank test. Results indicate that fuel economy for the Nevada hybrid bus was 29.6% better than for the Nevada control bus, and fuel economy for the Sigourney hybrid bus was 39.2% higher than for the Sigourney control bus. Both differences were statistically significant.

  6. Determination of the transient parameters of synchronous machines by the finite element method considering the characteristic effect in the shock absorber buses; Determinacao dos parametros transitorios de maquinas sincronas pelo metodo dos elementos finitos considerando o efeito pelicular nas barras amortecedoras

    Energy Technology Data Exchange (ETDEWEB)

    Nabeta, Silvio Ikuyo; Cardoso, Jose Roberto [Sao Paulo Univ., SP (Brazil). Escola Politecnica; Foggia, Albert; Coulomb, Jean Louis; Reyne, Gilbert [Institut National Polytechnique, 38 - Grenoble (France)

    1995-12-31

    This work presents the determination of the parameters of a hydro generator through the simulation of the frequency response test. The special characteristic of this work is that it takes into consideration shock absorbers buses, which are sites of induced currents when the peculiar effect is present and require that sub-transients parameters are analysed. Simulation results are analysed and compared to the obtained values when the traditional three-phase short circuit test is used 8 figs., 2 tabs., 13 refs.

  7. Reduction of glycine particle size by impinging jet crystallization.

    Science.gov (United States)

    Tari, Tímea; Fekete, Zoltán; Szabó-Révész, Piroska; Aigner, Zoltán

    2015-01-15

    The parameters of crystallization processes determine the habit and particle size distribution of the products. A narrow particle size distribution and a small average particle size are crucial for the bioavailability of poorly water-soluble pharmacons. Thus, particle size reduction is often required during crystallization processes. Impinging jet crystallization is a method that results in a product with a reduced particle size due to the homogeneous and high degree of supersaturation at the impingement point. In this work, the applicability of the impinging jet technique as a new approach in crystallization was investigated for the antisolvent crystallization of glycine. A factorial design was applied to choose the relevant crystallization factors. The results were analysed by means of a statistical program. The particle size distribution of the crystallized products was investigated with a laser diffraction particle size analyser. The roundness and morphology were determined with the use of a light microscopic image analysis system and a scanning electron microscope. Polymorphism was characterized by differential scanning calorimetry and powder X-ray diffraction. Headspace gas chromatography was utilized to determine the residual solvent content. Impinging jet crystallization proved to reduce the particle size of glycine. The particle size distribution was appropriate, and the average particle size was an order of magnitude smaller (d(0.5)=8-35 μm) than that achieved with conventional crystallization (d(0.5)=82-680 μm). The polymorphic forms of the products were influenced by the solvent ratio. The quantity of residual solvent in the crystallized products was in compliance with the requirements of the International Conference on Harmonization.

  8. Modeling particle size distributions by the Weibull distribution function

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Zhigang (Rogers Tool Works, Rogers, AR (United States)); Patterson, B.R.; Turner, M.E. Jr (Univ. of Alabama, Birmingham, AL (United States))

    1993-10-01

    A method is proposed for modeling two- and three-dimensional particle size distributions using the Weibull distribution function. Experimental results show that, for tungsten particles in liquid phase sintered W-14Ni-6Fe, the experimental cumulative section size distributions were well fit by the Weibull probability function, which can also be used to compute the corresponding relative frequency distributions. Modeling the two-dimensional section size distributions facilitates the use of the Saltykov or other methods for unfolding three-dimensional (3-D) size distributions with minimal irregularities. Fitting the unfolded cumulative 3-D particle size distribution with the Weibull function enables computation of the statistical distribution parameters from the parameters of the fit Weibull function.

  9. Selective follicular targeting by modification of the particle sizes.

    Science.gov (United States)

    Patzelt, Alexa; Richter, Heike; Knorr, Fanny; Schäfer, Ulrich; Lehr, Claus-Michael; Dähne, Lars; Sterry, Wolfram; Lademann, Juergen

    2011-02-28

    Hair follicles represent interesting target sites for topically applied substances such as topical vaccinations or agents used in the field of regenerative medicine. In recent years, it could be shown that particles penetrate very effectively into the hair follicles. In the present study, the influence of particle size on the follicular penetration depths was examined. The penetration depths of two different types of particles sized 122 to 1000 nm were determined in vitro on porcine skin. The results revealed that the particles of medium size (643 and 646 nm, respectively) penetrated deeper into the porcine hair follicles than smaller or larger particles. It was concluded that by varying the particle size, different sites within the porcine hair follicle can be targeted selectively. For the human terminal hair follicle, the situation can be expected to be similar due to a similar size ratio of the hair follicles.

  10. Mining the Shirt Sizes for Indian Men by Clustered Classification

    Directory of Open Access Journals (Sweden)

    Kumaravel Appavoo

    2012-06-01

    Full Text Available In garment production engineering, sizing system plays an important role for manufacturing of clothing. The standards for defining the size label are a critical issue. Locating the right garment size for a customer depends on the label as an interface. In this research work intend to approach that it could be used for developing sizing systems by data mining techniques applied to Indian anthropometric dataset. We propose a new approach of two-stage data mining procedure for labelling the shirt types exclusively for Indian men. In the first stage , clustering technique applied on the original dataset, to categorise the size labels. Then these clusters are used for supervised learning in the second stage for classification. A sizing system classifies a specific population into homogeneous subgroups based on some key body dimensions. The space with these dimensions gives raise to complexity for finding uniform standards. This enables us to have an interface as a communication tool among manufacturers, retailers and consumers. This sizing system is developed for the men’s age ranges between 25 and 66 years. Main attribute happens to be the chest size as clearly visible in the data set. We have obtained classifications for men’s shirt attributes based on clustering techniques.

  11. Nanometer sized structures grown by pulsed laser deposition

    KAUST Repository

    ElZein, Basma

    2015-10-01

    Nanometer sized materials can be produced by exposing a target to a laser source to remove material from the target and deposit the removed material onto a surface of a substrate to grow a thin film in a vacuum chamber

  12. Measurements of Protein-Protein Interactions by Size Exclusion Chromatography

    OpenAIRE

    Bloustine, J.; Berejnov, V.; Fraden, S

    2003-01-01

    A method is presented for determining second virial coefficients (B2) of protein solutions from retention time measurements in size exclusion chromatography. We determine B2 by analyzing the concentration dependence of the chromatographic partition coefficient. We show the ability of this method to track the evolution of B2 from positive to negative values in lysozyme and bovine serum albumin solutions. Our size exclusion chromatography results agree quantitatively with data obtained by light...

  13. Model catalysis by size-selected cluster deposition

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Scott [Univ. of Utah, Salt Lake City, UT (United States)

    2015-11-20

    This report summarizes the accomplishments during the last four years of the subject grant. Results are presented for experiments in which size-selected model catalysts were studied under surface science and aqueous electrochemical conditions. Strong effects of cluster size were found, and by correlating the size effects with size-dependent physical properties of the samples measured by surface science methods, it was possible to deduce mechanistic insights, such as the factors that control the rate-limiting step in the reactions. Results are presented for CO oxidation, CO binding energetics and geometries, and electronic effects under surface science conditions, and for the electrochemical oxygen reduction reaction, ethanol oxidation reaction, and for oxidation of carbon by water.

  14. 13 CFR 121.303 - What size procedures are used by SBA before it makes a formal size determination?

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false What size procedures are used by SBA before it makes a formal size determination? 121.303 Section 121.303 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION SMALL BUSINESS SIZE REGULATIONS Size Eligibility Provisions...

  15. [Determination of pancreatic size by ultrasound in diabetics].

    Science.gov (United States)

    Ravina, A; Shreibman, I; Gershin, M; Minuchin, O

    1991-04-01

    Determination of pancreatic size by ultrasound in diabetics showed that the pancreas is smallest in Type 1 (IDDM) diabetes (7.15 +/- 0.55 cm), larger in Type 2 (9.71 +/- 0.81 cm), but significantly greater in nondiabetics (15.17 +/- 0.79 cm). In 10/12 patients referred because of reactive hypoglycemia there was insulin-resistance and the pancreas was smaller than 8 cm. There was no correlation between pancreatic size and duration of diabetes, body size, or body mass index. More normal controls of various ages are needed for definitive assessment.

  16. Adjusting parameters of aortic valve stenosis severity by body size

    DEFF Research Database (Denmark)

    Minners, Jan; Gohlke-Baerwolf, Christa; Kaufmann, Beat A

    2014-01-01

    BACKGROUND: Adjustment of cardiac dimensions by measures of body size appears intuitively convincing and in patients with aortic stenosis, aortic valve area (AVA) is commonly adjusted by body surface area (BSA). However, there is little evidence to support such an approach. OBJECTIVE: To identify...... the adequate measure of body size for the adjustment of aortic stenosis severity. METHODS: Parameters of aortic stenosis severity (jet velocity, mean pressure gradient (MPG) and AVA) and measures of body size (height, weight, BSA and body mass index (BMI)) were analysed in 2843 consecutive patients with aortic...... stenosis (jet velocity ≥2.5 m/s) and related to outcomes in a second cohort of 1525 patients from the Simvastatin/Ezetimibe in Aortic Stenosis (SEAS) study. RESULTS: Whereas jet velocity and MPG were independent of body size, AVA was significantly correlated with height, weight, BSA and BMI (Pearson...

  17. Size fractionation by slalom chromatography and hydrodynamic chromatography

    OpenAIRE

    Dias, Ricardo P.

    2008-01-01

    Hydrodynamic chromatography, also called separation by flow, is based on the use of the parabolic flow profile occurring in open capillaries or in the pores from a column filled with non-porous particles. The hydrodynamic chromatography separation medium, if any, is much simpler than that from size exclusion chromatography (porous particles), the former technique being used in the size-fractionation of many colloids and macromolecules. The transition between hydrodynamic chromatography (obtai...

  18. Evaluation of Alternative Field Buses for Lighting ControlApplications

    Energy Technology Data Exchange (ETDEWEB)

    Koch, Ed; Rubinstein, Francis

    2005-03-21

    The Subcontract Statement of Work consists of two major tasks. This report is the Final Report in fulfillment of the contract deliverable for Task 1. The purpose of Task 1 was to evaluate existing and emerging protocols and standards for interfacing sensors and controllers for communicating with integrated lighting control systems in commercial buildings. The detailed task description follows: Task 1. Evaluate alternative sensor/field buses. The objective of this task is to evaluate existing and emerging standards for interfacing sensors and controllers for communicating with integrated lighting control systems in commercial buildings. The protocols to be evaluated will include at least: (1) 1-Wire Net, (2) DALI, (3) MODBUS (or appropriate substitute such as EIB) and (4) ZigBee. The evaluation will include a comparative matrix for comparing the technical performance features of the different alternative systems. The performance features to be considered include: (1) directionality and network speed, (2) error control, (3) latency times, (4) allowable cable voltage drop, (5) topology, and (6) polarization. Specifically, Subcontractor will: (1) Analyze the proposed network architecture and identify potential problems that may require further research and specification. (2) Help identify and specify additional software and hardware components that may be required for the communications network to operate properly. (3) Identify areas of the architecture that can benefit from existing standards and technology and enumerate those standards and technologies. (4) Identify existing companies that may have relevant technology that can be applied to this research. (5) Help determine if new standards or technologies need to be developed.

  19. Synthesis of size-controlled Bi particles by electrochemical deposition

    Indian Academy of Sciences (India)

    C N Tharamani; H C Thejaswini; S Sampath

    2008-06-01

    Small sized bismuth particles are prepared by an electrochemical method using a triple voltage pulse technique. The bath composition and electrochemical parameters are optimized to yield monodisperse particles. The particles have been characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, UV-visible spectroscopy and X-ray diffraction technique. The particles, as deposited, are highly crystalline in nature and the particle size and shape get tuned depending on the conditions of deposition.

  20. Self-service fare collection on buses in Portland, Oregon. Final report, Septtember 1980-April 1984

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, D.; Harper, W.; Schueftan, O.

    1986-09-01

    In 1980, the Urban Mass Transportation Administration (UMTA) awarded grants to the Tri-County Metropolitan Transportation District (TRI-MET) to implement self-service fare collection (SSFC) on its bus system. TRI-MET, the transit authority serving Portland, Oregon, is the second authority in the United States to use SSFC and the first to use it on buses. TRI-MET expected SSFC to improve bus productivity, facilitate distance-based fares, and reduce fare evasion. Problems encountered with SSFC on buses in Portland included increased fare evasion, high enforcement costs, no productivity improvements, low surcharge/ fine collections, overburdened courts, and increased vandalism. These problems need to be overcome before SSFC can be successful on buses in other U.S. cities.

  1. Fuel Cell Buses in U.S. Transit Fleets: Current Status 2010

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, L.; Chandler, K.; Gigakis, C.

    2010-11-01

    This status report, fourth in a series of annual status reports from the U.S. Department of Energy's National Renewable Energy Laboratory, summarizes progress and accomplishments from demonstrations of fuel cell transit buses in the United States. This year's assessment report provides the results from the fifth year of operation of five Van Hool, ISE, and UTC Power fuel cell buses operating at AC Transit, SunLine, and CTTRANSIT. The achievements and challenges of this bus design, implementation, and operating are presented, with a focus on the next steps for implementing larger numbers and new and different designs of fuel cell buses. The major positive result from nearly five years of operation is the dramatic increase in reliability experienced for the fuel cell power system.

  2. Effectivness Of The Failure Rate On Maintenance Costs Of The City Buses

    Directory of Open Access Journals (Sweden)

    Ignaciuk Piotr

    2015-11-01

    Full Text Available The purpose of this paper was to present a failure rate and maintenance cost comparison for two types of city transport buses. The paper presents in detail a case study of well known bus brands used at Municipal Transport Company in Lublin. A failure index of all functional and constructional systems of the vehicles and their technical availability with regards to calendar time was determined. The paper also presents analysis of the factors related to maintenance costs of buses, including costs of fluids, repair costs and maintenance service. It has been demonstrated, that both analyzed buses generate similar maintenance costs, while their failures and technical availability differ significantly in operational practice. These differences are particularly evident in relation to the cumulative costs of repairs.

  3. Fuel Cell Buses in U.S. Transit Fleets: Current Status 2016

    Energy Technology Data Exchange (ETDEWEB)

    Eudy, Leslie [National Renewable Energy Lab. (NREL), Golden, CO (United States); Post, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States); Jeffers, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-11-01

    This report, published annually, summarizes the progress of fuel cell electric bus development in the United States and discusses the achievements and challenges of introducing fuel cell propulsion in transit. The report provides a summary of results from evaluations performed by the National Renewable Energy Laboratory. Funding for this effort is provided by the U.S. Department of Energy's Fuel Cell Technologies Office within the Office of Energy Efficiency and Renewable Energy and by the U.S. Department of Transportation's Federal Transit Administration. The 2016 summary results primarily focus on the most recent year for each demonstration, from August 2015 through July 2016. The results for these buses account for more than 550,000 miles traveled and 59,500 hours of fuel cell power system operation. The primary results presented in the report are from three demonstrations of two different fuel-cell-dominant bus designs: Zero Emission Bay Area Demonstration Group led by Alameda-Contra Costa Transit District (AC Transit) in California; American Fuel Cell Bus Project at SunLine Transit Agency in California; and American Fuel Cell Bus Project at the University of California at Irvine.

  4. Stability of polymersomes prepared by size exclusion chromatography and extrusion

    OpenAIRE

    Bartenstein, Julia E.; Robertson, James; Battaglia, Giuseppe; Wuge H. Briscoe

    2016-01-01

    In this work, stability of poly(butadiene)-poly(ethylene oxide) (PBD-PEO) polymersomes, self-assembled from two polymers with different molecular weights (PBD32-PEO21 and PBD125-PEO80) in either pure H2O or phosphate buffered saline (PBS), is studied. Polymersome dispersions usually show large polydispersity, and it is thus desirable to separate different-sized vesicles if a narrow size distribution is required, e.g. for model systems in certain applications. This is typically achieved by ext...

  5. On the maximum grain size entrained by photoevaporative winds

    CERN Document Server

    Hutchison, Mark A; Maddison, Sarah T

    2016-01-01

    We model the behaviour of dust grains entrained by photoevaporation-driven winds from protoplanetary discs assuming a non-rotating, plane-parallel disc. We obtain an analytic expression for the maximum entrainable grain size in extreme-UV radiation-driven winds, which we demonstrate to be proportional to the mass loss rate of the disc. When compared with our hydrodynamic simulations, the model reproduces almost all of the wind properties for the gas and dust. In typical turbulent discs, the entrained grain sizes in the wind are smaller than the theoretical maximum everywhere but the inner disc due to dust settling.

  6. Analysis of size correlations for microdroplets produced by ultrasonic atomization.

    Science.gov (United States)

    Dalmoro, Annalisa; Barba, Anna Angela; d'Amore, Matteo

    2013-01-01

    Microencapsulation techniques are widely applied in the field of pharmaceutical production to control drugs release in time and in physiological environments. Ultrasonic-assisted atomization is a new technique to produce microencapsulated systems by a mechanical approach. Interest in this technique is due to the advantages evidenceable (low level of mechanical stress in materials, reduced energy request, reduced apparatuses size) when comparing it to more conventional techniques. In this paper, the groundwork of atomization is introduced, the role of relevant parameters in ultrasonic atomization mechanism is discussed, and correlations to predict droplets size starting from process parameters and material properties are presented and tested.

  7. Analysis of Size Correlations for Microdroplets Produced by Ultrasonic Atomization

    Directory of Open Access Journals (Sweden)

    Annalisa Dalmoro

    2013-01-01

    Full Text Available Microencapsulation techniques are widely applied in the field of pharmaceutical production to control drugs release in time and in physiological environments. Ultrasonic-assisted atomization is a new technique to produce microencapsulated systems by a mechanical approach. Interest in this technique is due to the advantages evidenceable (low level of mechanical stress in materials, reduced energy request, reduced apparatuses size when comparing it to more conventional techniques. In this paper, the groundwork of atomization is introduced, the role of relevant parameters in ultrasonic atomization mechanism is discussed, and correlations to predict droplets size starting from process parameters and material properties are presented and tested.

  8. Size of the top jet drop produced by bubble bursting

    CERN Document Server

    Ghabache, Elisabeth

    2016-01-01

    As a bubble bursts at a liquid-air interface, a tiny liquid jet rises and can release the so-called \\textit{jet drops}. In this paper, the size of the top jet drop produced by a bubble bursting is investigated experimentally. We determine, and discuss, the first scaling law enabling the determination of the top jet drop size as a function of the corresponding mother bubble radius and the liquid properties (viscosity, surface tension, density), along with its regime of existence. Furthermore, in the aim of decoupling experimentally the effects of bubble collapse and jet dynamics on the drop detachment, we propose a new scaling providing the top drop size only as a function of the jet velocity and liquid parameters. In particular, this allows us to untangle the intricate roles of viscosity, gravity and surface tension in the \\textit{end-pinching} of the bubble bursting jet.

  9. Estimation of coal particle size distribution by image segmentation

    Institute of Scientific and Technical Information of China (English)

    Zhang Zelin; Yang Jianguo; Ding Lihua; Zhao Yuemin

    2012-01-01

    Several industrial coal processes are largely determined by the distribution of particle sizes in their feed.Currently these parameters are measured by manual sampling,which is time consuming and cannot provide real time feedback for automatic control purposes.In this paper,an approach using image segmentation on images of overlapped coal particles is described.The estimation of the particle size distribution by number is also described.The particle overlap problem was solved using image enhancement algorithms that converted those image parts representing material in lower layers to black.Exponential high-pass filter (EHPF) algorithms were used to remove the texture from particles on the surface.Finally,the edges of the surface particles were identified by morphological edge detection.These algorithms are described in detail as is the method of extracting the coal particle size.Tests indicate that using more coal images gives a higher accuracy estimate.The positive absolute error of 50 random tests was consistently less than 2.5% and the errors were reduced as the size of the fraction increased.

  10. Size separation of DNA molecules by pulsed electric field dielectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Nedelcu, S [National Institute for R and D in Microtechnologies, Str. Erou Iancu Nicolae 32B, PO Box 38-160, 023573 Bucharest (Romania); Watson, J H P [School of Physics and Astronomy, University of Southampton, Highfield, SO17 1BJ, Southampton (United Kingdom)

    2004-08-07

    In this paper we propose an electrode design and a switching pattern of the applied DC electrode potentials for a microfluidic device to be used in size separation of DNA molecules. Estimates on the separation resolution, which are based on numerical solutions of a Newton-type equation on time-averaged quantities, are presented for an input batch sample of DNA fragments with sizes up to 220 base pairs (bp). The active area of the device (which can be microfabricated by standard photolitographic techniques) is a channel 6 {mu}m wide, 8 {mu}m deep and 150 {mu}m in length, flanked by 23 plane parallel integrated electrodes, individually addressed with low DC voltages, up to {+-} 25 V. In the active area a time-dependent non-uniform electric field, or a travelling dielectrophoretic wave (TDW) is being produced. In order to enhance the separation resolution, the polarization DC potentials are switched with a relatively high frequency ({approx} 10{sup -7} s), which is chosen accordingly with the buffer conductivity and dielectric constants of the fluid and particles. Since the external field is of DC type, we put forward an explanatory model of the dielectric response of the DNA to the time-dependent applied field. We then numerically investigate the size-dependent response of the DNA in a low conductivity buffer ({approx}0.01 {omega}{sup -1} m{sup -1}) under the influence of the electric field, which is calculated by means of the method of moments. The results of the computer modelling indicate the existence of a threshold value for the size of the successfully transported molecules, which can be adjusted by varying the velocity of the dielectrophoretic wave produced by the system. The estimated error in selecting a chosen group of molecules with sizes above a specified value is about 5 bp, while the processing times are of the order of hundred of seconds.

  11. Influence of malfunctions of the maintenance activities on the urban buses fuel consumption

    Science.gov (United States)

    George, Crişan; Nicolae, Filip

    2014-06-01

    Optimization of activities with the aim to provide quality service in conditions of high profitability, is one of the main objectives chased by managers in transportation companies. As a consequence, directing the attention towards monitoring of maintenance activities of vehicles fleet, can achieve desired results. Two of the most important issues related to the maintenance activity, is the increase of reliability and reduction of fuel consumption of the vehicles fleet. Aforementioned actions represents a way forward for raising the quality and profitability of services offered. In this paper, the main ways of monitoring the fuel consumption, in order to reduce it and increase the reliability of transportation vehicles fleet, are presented. For the evaluation of the maintenance system and the degree of influence of malfunctions recorded on the fuel consumption, using the Pareto -ABC method, following case study on a fleet of buses for urban public transport has been conducted. Results obtained highlights the deficiencies of the maintenance process carried out and constitutes a solid base for the reorganization of the maintenance activity, involving preventive maintenance activities, in order to contribute decisively to the results targeted by the management of transport companies.

  12. A Model for the Stop Planning and Timetables of Customized Buses

    Science.gov (United States)

    Yang, Yang

    2017-01-01

    Customized buses (CBs) are a new mode of public transportation and an important part of diversified public transportation, providing advanced, attractive and user-led service. The operational activity of a CB is planned by aggregating space–time demand and similar passenger travel demands. Based on an analysis of domestic and international research and the current development of CBs in China and considering passenger travel data, this paper studies the problems associated with the operation of CBs, such as stop selection, line planning and timetables, and establishes a model for the stop planning and timetables of CBs. The improved immune genetic algorithm (IIGA) is used to solve the model with regard to the following: 1) multiple population design and transport operator design, 2) memory library design, 3) mutation probability design and crossover probability design, and 4) the fitness calculation of the gene segment. Finally, a real-world example in Beijing is calculated, and the model and solution results are verified and analyzed. The results illustrate that the IIGA solves the model and is superior to the basic genetic algorithm in terms of the number of passengers, travel time, average passenger travel time, average passenger arrival time ahead of schedule and total line revenue. This study covers the key issues involving operational systems of CBs, combines theoretical research and empirical analysis, and provides a theoretical foundation for the planning and operation of CBs. PMID:28056041

  13. The life cycle assessment of alternative fuel chains for urban buses and trolleybuses.

    Science.gov (United States)

    Kliucininkas, L; Matulevicius, J; Martuzevicius, D

    2012-05-30

    This paper describes a comparative analysis of public transport alternatives in the city of Kaunas, Lithuania. An LCA (Life Cycle Assessment) inventory analysis of fuel chains was undertaken using the midi urban bus and a similar type of trolleybus. The inventory analysis of fuel chains followed the guidelines provided by the ISO 14040 and ISO 14044 standards. The ReCiPe Life Cycle Impact Assessment (LCIA) methodology was used to quantify weighted damage originating from five alternative fuel chains. The compressed biogas fuel chain had the lowest weighted damage value, namely 45.7 mPt/km, whereas weighted damage values of the fuel chains based on electricity generation for trolleybuses were 60.6 mPt/km (for natural gas) and 78.9 mPt/km (for heavy fuel oil). The diesel and compressed natural gas fuel chains exhibited considerably higher damage values of 114.2 mPt/km and 132.6 mPt/km, respectively. The comparative life cycle assessment of fuel chains suggested that biogas-powered buses and electric trolleybuses can be considered as the best alternatives to use when modernizing the public transport fleet in Kaunas.

  14. IFA and PIFA Size Reduction by Using a Stub Loading

    Directory of Open Access Journals (Sweden)

    Jose Alfredo Tirado-Mendez

    2013-01-01

    Full Text Available A proposed technique for size reduction of a conventional inverted-F antenna (IFA and a planar inverted-F antenna (PIFA by employing a reactive load generated by a short-circuited stub is presented. The reduction factor of both antennas is around 30%, and the main parameters of the devices are preserved, including a fractional bandwidth of 4% and a gain of −2 dB. Both antennas operate around 1.5 GHz.

  15. Particle size and packing characterization by diffuse light transmission

    Institute of Scientific and Technical Information of China (English)

    Henrik Ehlers; Jyrki Hein(a)m(a)ki; Jouko Yliruusi

    2012-01-01

    Particle size,packing density and blend composition of glass ballotini,microcrystalline cellulose pellets and theophylline granules were studied by diffuse light transmission.Diffuse visible light was directed to the sample and the intensity of the light transmitted to the opposite side of the sample was measured through a diffusing lens using a phototransistor.Light transmission was found to decrease with decreasing particle size and with increasing packing density.There was a correlation,though somewhat irregular,between light transmission and particle size for glass ballotini and microcrystalline cellulose pellets,and a strong near-linear correlation between light transmission and particle size for theophylline granules.The effect of packing density on light transmission was significant.Differentiating the composition of binary blends of microcrystalline cellulose pellets and glass ballotini and blends of theophylline granules was found possible on the basis of light transmission.The method proposed showed potential as a rapid,simple and inexpensive analytical tool for basic process diagnostics.

  16. Domain and droplet sizes in emulsions stabilized by colloidal particles

    Science.gov (United States)

    Frijters, Stefan; Günther, Florian; Harting, Jens

    2014-10-01

    Particle-stabilized emulsions are commonly used in various industrial applications. These emulsions can present in different forms, such as Pickering emulsions or bijels, which can be distinguished by their different topologies and rheology. We numerically investigate the effect of the volume fraction and the uniform wettability of the stabilizing spherical particles in mixtures of two fluids. For this, we use the well-established three-dimensional lattice Boltzmann method, extended to allow for the added colloidal particles with non-neutral wetting properties. We obtain data on the domain sizes in the emulsions by using both structure functions and the Hoshen-Kopelman (HK) algorithm, and we demonstrate that both methods have their own (dis)advantages. We confirm an inverse dependence between the concentration of particles and the average radius of the stabilized droplets. Furthermore, we demonstrate the effect of particles detaching from interfaces on the emulsion properties and domain-size measurements.

  17. Analysis of Size Correlations for Microdroplets Produced by Ultrasonic Atomization

    OpenAIRE

    Annalisa Dalmoro; Anna Angela Barba; Matteo d’Amore

    2013-01-01

    Microencapsulation techniques are widely applied in the field of pharmaceutical production to control drugs release in time and in physiological environments. Ultrasonic-assisted atomization is a new technique to produce microencapsulated systems by a mechanical approach. Interest in this technique is due to the advantages evidenceable (low level of mechanical stress in materials, reduced energy request, reduced apparatuses size) when comparing it to more conventional techniques. In this pape...

  18. Transportation of Wheelchair Seated Students in School Buses: A Review of State Policy

    Science.gov (United States)

    Moore, Britta; Fuhrman, Susan; Karg, Patricia

    2010-01-01

    This study quantitatively reviews publicly available state policies as they relate to the transportation of wheelchair-seated students in school buses. Inclusion of best practices in specially equipped school bus and driver training policies was assessed. Key points of interest within state policies were identified based on site visits, common…

  19. Comparative study of fuel cell, battery and hybrid buses for renewable energy constrained areas

    Science.gov (United States)

    Stempien, J. P.; Chan, S. H.

    2017-02-01

    Fuel cell- and battery-based public bus technologies are reviewed and compared for application in tropical urban areas. This paper scrutinizes the reported literature on fuel cell bus, fuel cell electric bus, battery electric bus, hybrid electric bus, internal combustion diesel bus and compressed natural gas bus. The comparison includes the capital and operating costs, fuel consumption and fuel cycle emissions. To the best of authors knowledge, this is the first study to holistically compare hydrogen and battery powered buses, which is the original contribution of this paper. Moreover, this is the first study to focus on supplying hydrogen and electricity from fossil resources, while including the associated emissions. The study shows that compressed natural gas and hybrid electric buses appear to be the cheapest options in terms of total cost of ownership, but they are unable to meet the EURO VI emissions' standard requirement. Only fuel cell based buses have the potential to achieve the emissions' standard when the fuel cycle based on fossil energy was considered. Fuel cell electric buses are identified as a technology allowing for the largest CO2 emission reduction, making ∼61% decrease in annual emissions possible.

  20. 40 CFR 52.263 - Priority treatment for buses and carpools-Los Angeles Region.

    Science.gov (United States)

    2010-07-01

    ... § 52.263 Priority treatment for buses and carpools—Los Angeles Region. (a) Definitions: (1) “Carpool” means a vehicle containing three or more persons. (2) “Bus/carpool lane” means a lane on a street or... agencies to which legal authority has been delegated, shall establish the following system of...

  1. Leadership Thrust of Urban School Educators for Meeting the Challenge of Busing.

    Science.gov (United States)

    Sommerville, Joseph C.

    Based on a nationwide survey of urban school administrators, personal experiences of the author, and a review of relevant desegregation literature, this paper explores the role of administrators in the achievement of the objectives of busing for school desegregation. Findings cited from the survey include: (1) peak periods of conflict occur in the…

  2. An introduction on the demonstration performance of fuel cell buses (FCB) in Beijing

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Since the 1990’s, hydrogen has found broad use in the traffic segment. Compared with conventional ones, hydrogen fuelled vehicles, a new generation of clean vehicles, produce no pollutants, with higher energy efficiency. In today’s world where the pollution is tougher, the "Zero Pollution" fuel cell buses display a

  3. Seat Belts in School Buses: A Technical Analysis of the Literature.

    Science.gov (United States)

    Splaine, Pam; Frankel, Steven M.

    This report, prepared for the Montgomery County (Maryland) Public Schools superintendent and board members, identifies the questions concerning seat belt use in school buses, examines relevant literature, and draws some conclusions. According to the literature, seat belts are one of many alternative and interdependent safety devices built into…

  4. 76 FR 53102 - Federal Motor Vehicle Safety Standards; Denial of Petition for Rulemaking; School Buses

    Science.gov (United States)

    2011-08-25

    ... belt use, the effects on bus discipline, the attitudes of other stakeholders, the loss of capacity... the past 34 years that compartmentalization and the school bus safety standards have been in effect... requiring seat belts on large school buses would protect passengers against an unreasonable risk of death...

  5. 26 CFR 41.4483-2 - Exemption for certain transit-type buses.

    Science.gov (United States)

    2010-04-01

    ... the same facts as those stated in Example (1), except that the X Transit Company commences operation... the same facts as those stated in Example (1), except that the X Transit Company commences operation... 26 Internal Revenue 16 2010-04-01 2010-04-01 true Exemption for certain transit-type buses....

  6. Efficiency evaluation of gas fuelled and electric driven buses in the public transport sector

    Energy Technology Data Exchange (ETDEWEB)

    Aigner, Tobias Alexander

    2013-07-01

    The following report evaluates the efficiency of gas fuelled and electric driven buses in the public transport sector on a theoretical basis. The results indicate that the combination of CHP power plants and electric driven buses reach an overall efficiency of about 51% throughout the production chain (Well-to-Wheel), including heat distribution losses. The overall Well-to-Wheel efficiency for conventional gas turbines without heat recovery decreases to around 28%. For gas fuelled buses the Well-to-Wheel efficiency is about 30%. The Co2-emissions are evaluated based on the example of a #Left Double Quotation Mark#Volvo B10L CNG#Right Double Quotation Mark# gas bus and the electric driven #Left Double Quotation Mark#Eurabus 600#Right Double Quotation Mark#. The low energy consumption of the electric driven bus results in Co2-emissions of only 181.4 g Co2/km (Grid-to-Wheel). Depending on the utilised power plant technology the overall Co2-emissions (Well-to-Wheel) amount to 307.5 g Co2/km for a CHP power plant and 553.5 g Co2/km for a conventional gas turbine. On the other hand, gas fuelled buses emit about 1.25 kg Co2/km (Tank-to-Wheel), which is eightfold the emissions of an electrical bus. The Well-to-Tank emissions further increase to about 1.32 kg Co2/km. The emission calculation is based on real gas consumption data from a Norwegian public transport utility. The results indicate that the combination of CHP plants and electrical buses provide a much higher efficiency while reducing Co2-emissions. (author)

  7. Crack detection and sizing technique by ultrasonic and electromagnetic methods

    Energy Technology Data Exchange (ETDEWEB)

    Komura, Ichiro E-mail: ichiro.komura@toshiba.co.jp; Hirasawa, Taiji; Nagai, Satoshi; Takabayashi, Jun-ichi; Naruse, Katsuhiko

    2001-06-01

    Improvements in defect detection and sizing capabilities for non-destructive inspection techniques have been required in order to ensure the reliable operation and life extension of nuclear power plants. For the volumetric inspection, the phased array UT technique has superior capabilities for beam steering and focusing to objective regions, and real-time B-scan imaging without mechanical scanning. In contrast to the conventional UT method, high-speed inspection is realized by the unique feature of the phased array technique. A 256-channel array system has developed for the inspection of weldment of BWR internal components such as core shrouds. The TOFD crack sizing technique also can be applied using this system. For the surface inspection, potential drop techniques and eddy current techniques have been improved, which combined the theoretical analysis. These techniques have the crack sizing capability for surface breaking cracks to which UT method is difficult to apply. This paper provides the recent progress of these phased array and electromagnetic inspection techniques.

  8. Estimation of udder cistern size in dairy ewes by ultrasonography

    Directory of Open Access Journals (Sweden)

    Pavol Makovick

    2015-07-01

    Full Text Available We studied the size of mammary cistern in ewes of 9 genotypes (purebred Improved Valachian (IV, purebred Tsigai (T, purebred Lacaune (LC and their crosses with genetic proportion of specialized dairy breeds Lacaune and East Friesian (EF - (25 %, 50 % and 75 % were evaluated. Dana were evaluated using REML methodology and MIXED procedure (SAS/STAT. The effect of genotype showed the highest influence (P<0.001 on the length and area of the left and right udder cisterns measurements. In purebred IV ewes, the average areas of the left and right udder cisterns sizes were obtained by using the side method were (1519.39±77.212 mm2 and 1558.45±74.480 mm2. In purebred T ewes, the average areas of the left and right udder cisterns were (1438.70±70.43 mm2 and 1418.68±67.952 mm2. These were significantly smaller than in purebred LC (2694.44±71.95 mm2 and 2693.48±69.340 mm2. The udder cistern areas were significantly higher in crosses with 25 %, 50 % and 75 % genetic proportion of specialized dairy breeds LC and EF, than in purebred IV and T ewes. The analyses showed that crossbreeding of IV with LC and EF and T with LC and EF considerably increases ewe‘s cistern size.

  9. Time step size limitation introduced by the BSSN Gamma Driver

    Energy Technology Data Exchange (ETDEWEB)

    Schnetter, Erik, E-mail: schnetter@cct.lsu.ed [Department of Physics and Astronomy, Louisiana State University, LA (United States)

    2010-08-21

    Many mesh refinement simulations currently performed in numerical relativity counteract instabilities near the outer boundary of the simulation domain either by changes to the mesh refinement scheme or by changes to the gauge condition. We point out that the BSSN Gamma Driver gauge condition introduces a time step size limitation in a similar manner as a Courant-Friedrichs-Lewy condition, but which is independent of the spatial resolution. We give a didactic explanation of this issue, show why, especially, mesh refinement simulations suffer from it, and point to a simple remedy. (note)

  10. Extraverted children are more biased by bowl sizes than introverts.

    Science.gov (United States)

    van Ittersum, Koert; Wansink, Brian

    2013-01-01

    Extraverted children are hypothesized to be most at risk for over-serving and overeating due to environmental cues--such as the size of dinnerware. A within-subject field study of elementary school students found that extraverted children served themselves 33.1% more cereal in larger bowls (16-oz) than in smaller (12-oz) bowls, whereas introverted children were unaffected by bowl size (+5.6%, ns). However, when children were asked by adults how much cereal they wanted to eat, both extraverted and introverted children requested more cereal when given a large versus small bowl. Insofar as extraverted children appear to be more biased by environmental cues, this pilot study suggests different serving styles are recommended for parents and other caregivers. They should serve extraverts, but allow introverts to serve themselves. Still, since the average child still served 23.2% more when serving themselves than when served by an adult, it might be best for caregivers to do the serving whenever possible--especially for extraverted children.

  11. Extraverted children are more biased by bowl sizes than introverts.

    Directory of Open Access Journals (Sweden)

    Koert van Ittersum

    Full Text Available Extraverted children are hypothesized to be most at risk for over-serving and overeating due to environmental cues--such as the size of dinnerware. A within-subject field study of elementary school students found that extraverted children served themselves 33.1% more cereal in larger bowls (16-oz than in smaller (12-oz bowls, whereas introverted children were unaffected by bowl size (+5.6%, ns. However, when children were asked by adults how much cereal they wanted to eat, both extraverted and introverted children requested more cereal when given a large versus small bowl. Insofar as extraverted children appear to be more biased by environmental cues, this pilot study suggests different serving styles are recommended for parents and other caregivers. They should serve extraverts, but allow introverts to serve themselves. Still, since the average child still served 23.2% more when serving themselves than when served by an adult, it might be best for caregivers to do the serving whenever possible--especially for extraverted children.

  12. Robust Clamping Force Control of an Electro-Mechanical Brake System for Application to Commercial City Buses

    Directory of Open Access Journals (Sweden)

    Sangjune Eum

    2017-02-01

    Full Text Available This paper proposes a sensor-less robust force control method for improving the control performance of an electro-mechanical brake (EMB which is applicable to commercial city buses. The EMB generates the accurate clamping force commanded by a driver through an independent motor control at each wheel instead of using existing mechanical components. In general, an EMB undergoes parameter variation and a backdrivability problem. For this reason, the cascade control strategy (e.g., force-position cascade control structure is proposed and the disturbance observer is employed to enhance control robustness against model variations. Additionally, this paper proposed the clamping force estimation method for a sensor-less control, i.e., the clamping force observer (CFO. Finally, in order to confirm the performance and effectiveness of a proposed robust control method, several experiments are performed and analyzed.

  13. Atomic size effects studied by transport in single silicide nanowires

    Science.gov (United States)

    Miccoli, I.; Edler, F.; Pfnür, H.; Appelfeller, S.; Dähne, M.; Holtgrewe, K.; Sanna, S.; Schmidt, W. G.; Tegenkamp, C.

    2016-03-01

    Ultrathin metallic silicide nanowires with extremely high aspect ratios can be easily grown, e.g., by deposition of rare earth elements on semiconducting surfaces. These wires play a pivotal role in fundamental research and open intriguing perspectives for CMOS applications. However, the electronic properties of these one-dimensional systems are extremely sensitive to atomic-sized defects, which easily alter the transport characteristics. In this study, we characterized comprehensively TbSi2 wires grown on Si(100) and correlated details of the atomic structure with their electrical resistivities. Scanning tunneling microscopy (STM) as well as all transport experiments were performed in situ using a four-tip STM system. The measurements are complemented by local spectroscopy and density functional theory revealing that the silicide wires are electronically decoupled from the Si template. On the basis of a quasiclassical transport model, the size effect found for the resistivity is quantitatively explained in terms of bulk and surface transport channels considering details of atomic-scale roughness. Regarding future applications the full wealth of these robust nanostructures will emerge only if wires with truly atomically sharp interfaces can be reliably grown.

  14. Inference by Minimizing Size, Divergence, or their Sum

    CERN Document Server

    Riedel, Sebastian; McCallum, Andrew

    2012-01-01

    We speed up marginal inference by ignoring factors that do not significantly contribute to overall accuracy. In order to pick a suitable subset of factors to ignore, we propose three schemes: minimizing the number of model factors under a bound on the KL divergence between pruned and full models; minimizing the KL divergence under a bound on factor count; and minimizing the weighted sum of KL divergence and factor count. All three problems are solved using an approximation of the KL divergence than can be calculated in terms of marginals computed on a simple seed graph. Applied to synthetic image denoising and to three different types of NLP parsing models, this technique performs marginal inference up to 11 times faster than loopy BP, with graph sizes reduced up to 98%-at comparable error in marginals and parsing accuracy. We also show that minimizing the weighted sum of divergence and size is substantially faster than minimizing either of the other objectives based on the approximation to divergence present...

  15. Improving tactile sensation in laparoscopic surgery by overcoming size restrictions

    Directory of Open Access Journals (Sweden)

    Wiederer C.

    2015-09-01

    Full Text Available Hepatic tumors appear as stiff inclusions within the surrounding soft, healthy tissue. In open surgery they are searched for by manual palpation with the gloved fingertip. However, to exploit the benefits of MIS it is mandatory to implement a substitution for the human sense of touch. Therefore, a tactile instrument has been developed with the aim of enlarging the sensing area at the tool tip once it enters the abdominal cavity through the trocar. The provision of a large sensitive surface enables the detection of nearly all sizes of tumors and decreases the time needed for the performance of this task. A prototype was manufactured by laser sintering in PA serving as a carrier for an existing flexible silicone sensor. Automated as well as manual subject palpation tests have shown that a prototypical instrument with a laterally opening lid would be a suitable device for tumor detection in laparoscopic liver surgery.

  16. An analysis of accident data for franchised public buses in Hong Kong.

    Science.gov (United States)

    Evans, W A; Courtney, A J

    1985-10-01

    This paper analyses data on accidents involving franchised public buses operating in Hong Kong. The data were obtained from the Royal Hong Kong Police, the Hong Kong Government Transport Department, the two major franchised bus operators and international sources. The analysis includes an international comparison of accidents with emphasis on the situation in Hong Kong compared to urban areas in the United Kingdom. An attempt has been made to identify the characteristics of bus accidents; accident incidence has been related to time of day, day of the week, time of year, weather conditions, driver's age and experience, hours on duty and policy-reported cause. The results indicate that Hong Kong has a high accident rate compared to Japan, the U.K. and the U.S.A., with particularly high pedestrian involvement rates. Bus accidents peak at around 9:00 AM and 4:00 PM but the accident rate is high throughout the day. Monday and Saturday appear to have a higher than average accident rate. The variability of accident rate throughout the year does not seem to be significant and the accident rate does not appear to be influenced by weather conditions. Older, more experienced drivers generally have a safer driving record than their younger, less experienced colleagues. Accident occurrence is related to the time the driver has been on duty. The paper questions the reliability of police-reported accident causation data and suggests improvements in the design of the accident report form and in the training of police investigators. The relevance of the Hong Kong study for accident research in general is also discussed.

  17. Prediction of Emissions from Biodiesel Fueled Transit Buses Using Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Abhisek Mudgal

    2011-06-01

    Full Text Available The growing demand of freight transportation and passenger cars has led to air pollution, green house gas emissions (especially CO2 and fuel supply concerns. Research has been carried out on biodiesel which is shown to generate lower emissions. However, the amount of emissions generated is not well understood which entails more vigorous data collection and development of emissions models. A comprehensive data collection plan was developed and emissions (NOx, HC, CO, CO2 and PM10 from biodiesel fueled transit buses were collected using a portable emissions measurement system (PEMS. Linear models were developed and tested for each emission. However, the models could not capture the emissions spikes well resulting in very low R2 values. Artificial neural networks (ANNs based models were then employed on this data because of their ability to handle nonlinearity and not requiring assumptions on the input data as needed by statistical models. Sensitivity analysis was performed on the input parameters, number of hidden layers, learning rate and learning algorithm to arrive at an optimum ANN architecture. The optimal architecture for this study was found to be two hidden layers with 50 hidden nodes for each of NOx, HC, CO, and PM and one hidden layer for CO2. The emissions were predicted using best-performance ANN models for each emission. Scatter-plots of observed versus predicted values showed R2 of 0.96, 0.94, 0.82, 0.98 and 0.78 for NOx, HC, CO, CO2 and PM emissions, respectively. Histogram on prediction error showed low frequency for large errors.

  18. Size histograms of gold nanoparticles measured by gravitational sedimentation.

    Science.gov (United States)

    Alexander, Colleen M; Goodisman, Jerry

    2014-03-15

    Sedimentation curves of gold nanoparticles in water were obtained by measuring the optical density of a suspension over time. The results are not subject to sampling errors, and refer to the particles in situ. Curves obtained simultaneously at several wave lengths were analyzed together to derive the size histogram of the sedimenting particles. The bins in the histogram were 5 nm wide and centered at diameters 60, 65, …, 110 nm. To get the histogram, we weighted previously calculated solutions to the Mason-Weaver sedimentation-diffusion equation for various particle diameters with absorption/scattering coefficients and size (diameter) abundances {c(j)}, and found the {c(j)} which gave the best fit to all the theoretical sedimentation curves. The effects of changing the number of bins and the wave lengths used were studied. Going to smaller bins would mean determining more parameters and require more wave lengths. The histograms derived from sedimentation agreed quite well in general with the histogram derived from TEM. Differences found for the smallest particle diameters are partly due to statistical fluctuations (TEM found only 1-2 particles out of 103 with these diameters). More important is that the TEM histogram indicates 12% of the particles have diameters of 75±2.5 nm, and the sedimentation histogram shows none. We show that this reflects the difference between the particles in situ, which possess a low-density shell about 1 nm thick, and the bare particles on the TEM stage. Correcting for this makes agreement between the two histograms excellent. Comparing sedimentation-derived with TEM-derived histograms thus shows differences between the particles in situ and on the TEM stage.

  19. Differential foraging preferences on seed size by rodents result in higher dispersal success of medium-sized seeds.

    Science.gov (United States)

    Cao, Lin; Wang, Zhenyu; Yan, Chuan; Chen, Jin; Guo, Cong; Zhang, Zhibin

    2016-11-01

    Rodent preference for scatter-hoarding large seeds has been widely considered to favor the evolution of large seeds. Previous studies supporting this conclusion were primarily based on observations at earlier stages of seed dispersal, or on a limited sample of successfully established seedlings. Because seed dispersal comprises multiple dispersal stages, we hypothesized that differential foraging preference on seed size by animal dispersers at different dispersal stages would ultimately result in medium-sized seeds having the highest dispersal success rates. In this study, by tracking a large number of seeds for 5 yr, we investigated the effects of seed size on seed fates from seed removal to seedling establishment of a dominant plant Pittosporopsis kerrii (Icacinaceae) dispersed by scatter-hoarding rodents in tropical forest in southwest China. We found that small seeds had a lower survival rate at the early dispersal stage where more small seeds were predated at seed stations and after removal; large seeds had a lower survival rate at the late dispersal stage, more large seeds were recovered, predated after being cached, or larder-hoarded. Medium-sized seeds experienced the highest dispersal success. Our study suggests that differential foraging preferences by scatter-hoarding rodents at different stages of seed dispersal could result in conflicting selective pressures on seed size and higher dispersal success of medium-sized seeds.

  20. Particle Size Influences Fibronectin Internalization and Degradation by Fibroblasts

    Science.gov (United States)

    Bozavikov, Peter

    Particle size is a crucial factor that influences the fate and biological impact of particles and their surface proteins upon internalization. Here, using fibronectin-coated polystyrene nanoparticles and microparticles we examined the effect of particle size on degradation of fibronectin. Microparticle uptake depended primarily on beta1 integrins and actin filaments, while nanoparticle uptake relied mainly on lipid rafts and specifically on clathrin-mediated endocytosis. Further, biotinylated fibronectin when coated on microparticles underwent more intracellular processing than fibronectin coated on to nanoparticles. Thus, particle size affects actin and clathrin- dependent internalization, which in turn regulates intracellular fibronectin degradation.

  1. Assessment of active pharmaceutical ingredient particle size in tablets by Raman chemical imaging validated using polystyrene microsphere size standards.

    Science.gov (United States)

    Kuriyama, Atsushi; Ozaki, Yukihiro

    2014-04-01

    Particle size is a critical parameter for controlling pharmaceutical quality. The aim of this study was to assess the size of the micrometer-scale active pharmaceutical ingredients (API) in tablets using Raman chemical imaging and to understand the effects of formulation on particle size. Model tablets containing National Institute of Standards and Technology traceable polystyrene microsphere size standards were developed to determine the binarization threshold value of Raman chemical images for API particle sizing in specific formulations and processes. Three sets of model tablets containing 5, 10, and 15 μm polystyrene microspheres, used to mimic API, were prepared using a commercial tablet formulation (Ebastel tablets, mean API particle size was about 5 μm). Raman mapping with a 50× objective (NA, 0.75) was applied to tablet cross-sections, and particle size of polystyrene microspheres was estimated from binary images using several binarization thresholds. Mean particle size for three sets of polystyrene microspheres showed good agreement between pre- and postformulation (the slope = 1.024, R = 1.000) at the specific threshold value ((mean + 0.5σ) of the polystyrene-specific peak intensity histogram), regardless of particle agglomeration, tablet surface roughness, and laser penetration depth. The binarization threshold value showed good applicability to Ebastel tablets, where the API-specific peak intensity histogram showed a pattern similar to that of polystyrene microspheres in model tablets. The model tablets enabled determination of an appropriate binarization threshold for assessing the mean particle size of micrometer-scale API in tablets by utilizing the unique physicochemical properties of polystyrene microspheres.

  2. Tuning the transmission phase by the dot size

    Science.gov (United States)

    Ţolea, F.; Ţolea, M.

    2017-01-01

    The phase shift of the electron's wave function after a tunneling event (i.e. the transmission phase) was at first measured for its fundamental or applicative relevance for quantum circuitry, but later the phase study self-motivated due to a number of unexpected results. One such result was the reduced increment of the phase on some resonances - with only fractions of π - in the few-electrons "mesoscopic" regime. In this paper we address such a regime for a rectangular quantum dot and compute the total phase increase on the first four resonances by means of accurate configuration-interaction method and a generalized Friedel sum rule as proposed by Rontani (2006) [17]. Our findings confirm that the electronic correlations reduce the on-resonance phase growth which is also found to decrease quasi-linearly with the dot size, the decrease being more pronounced as the number of electrons on the dot is raised. Sudden jumps (of small amplitude) of the phase are found to accompany ground states spin transitions.

  3. Sizing a rainwater harvesting cistern by minimizing costs

    Science.gov (United States)

    Pelak, Norman; Porporato, Amilcare

    2016-10-01

    Rainwater harvesting (RWH) has the potential to reduce water-related costs by providing an alternate source of water, in addition to relieving pressure on public water sources and reducing stormwater runoff. Existing methods for determining the optimal size of the cistern component of a RWH system have various drawbacks, such as specificity to a particular region, dependence on numerical optimization, and/or failure to consider the costs of the system. In this paper a formulation is developed for the optimal cistern volume which incorporates the fixed and distributed costs of a RWH system while also taking into account the random nature of the depth and timing of rainfall, with a focus on RWH to supply domestic, nonpotable uses. With rainfall inputs modeled as a marked Poisson process, and by comparing the costs associated with building a cistern with the costs of externally supplied water, an expression for the optimal cistern volume is found which minimizes the water-related costs. The volume is a function of the roof area, water use rate, climate parameters, and costs of the cistern and of the external water source. This analytically tractable expression makes clear the dependence of the optimal volume on the input parameters. An analysis of the rainfall partitioning also characterizes the efficiency of a particular RWH system configuration and its potential for runoff reduction. The results are compared to the RWH system at the Duke Smart Home in Durham, NC, USA to show how the method could be used in practice.

  4. Size-selected genomic libraries: the distribution and size-fractionation of restricted genomic DNA fragments by gel electrophoresis.

    Science.gov (United States)

    Gondo, Y

    1995-02-01

    By using one-dimensional genome scanning, it is possible to directly identify the restricted genomic DNA fragment that reflects the site of genetic change. The subsequent strategies to obtain the molecular clones of the corresponding restriction fragment are usually as follows: (i) the restriction of a mass quantity of an appropriate genomic DNA, (ii) the size-fractionation of the restricted DNA on a preparative electrophoresis gel in order to enrich the corresponding restriction fragment, (iii) the construction of the size-selected libraries from the fractionated genomic DNA, and (iv) the screening of the library to obtain an objective clone which is identified on the analytical genome scanning gel. A knowledge of the size distribution pattern of restriction fragments of the genomic DNA makes it possible to calculate the heterogeneity or complexity of the restriction fragment in each size-fraction. This manuscript first describes the distribution of the restriction fragments with respect to their length. Some examples of the practical application of this theory to genome scanning is then discussed using presumptive genome scanning gels. The way to calculate such DNA complexities in the prepared size-fractionated samples is also demonstrated. Such information should greatly facilitate the design of experimental strategies for the cloning of a certain size of genomic DNA after digestion with restriction enzyme(s) as is the case with genome scanning.

  5. Electronic structure and size of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods

    CERN Document Server

    Soriano, L; Sanchez-Agudo, M; Sanz, J M; Ahonen, P P; Kauppinen, E I; Palomares, F J; Bressler, P R

    2002-01-01

    A complete characterization of nanostructures has to deal both with electronic structure and dimensions. Here we present the characterization of TiO sub 2 nanoparticles of controlled size prepared by aerosol methods. The electronic structure of these nanoparticles was probed by x-ray absorption spectroscopy (XAS), the particle size by atomic force microscopy (AFM). XAS spectra show that the particles crystallize in the anatase phase upon heating at 500 sup o C, whereas further annealing at 700 sup o C give crystallites of 70 % anatase and 30 % rutile phases. Raising the temperature to 900 sup o C results in a complete transformation of the particles to rutile. AFM images reveal that the mean size of the anatase particles formed upon heating at 500 sup o C is 30 nm, whereas for the rutile particles formed upon annealing at 900 sup o C 90 nm were found. The results obtained by these techniques agree with XRD data. (author)

  6. Cerium dioxide with large particle size prepared by continuous precipitation

    Institute of Scientific and Technical Information of China (English)

    李梅; 王觅堂; 柳召刚; 胡艳宏; 吴锦绣

    2009-01-01

    Cerium dioxide(CeO2) has attracted much attention and has wide applications such as automotive exhaust catalysts,polishing materials for optical glasses and additives for advanced glasses,as well as cosmetic materials.The particle size and its distribution are key factors to the performance of the materials in the functional applications.However,control of particle size is still a challenge in materials synthesis.Therefore,continuous precipitation of cerium oxalate(precursor of ceria) was carried out at dif...

  7. MONODISPERSE MICRON-SIZED POLYACRYLAMIDE PARTICLES SYNTHESIZED BY DISPERSION POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Xin Hou; Bo Gao; Zhe-guo Zhang; Kang-de Yao

    2007-01-01

    Monodisperse micron-sized polyacrylamide (PAM) particles with a regular shape have been successfully prepared through dispersion polymerization of the monomer using a rotary reactor. FTIR and NMR spectroscopic results demonstrated the formation of PAM. POM and TEM observations revealed that PAM particles had a regular shape and good dispersity. A thick layer of surfactant (PVP) still existed on PAM particles after multiple centrifugation and ultrasonic re-dispersion in ethanol, which indicates a strong interaction between PVP and PAM. The effects of various polymerization factors on the average size of PAM particles have also been studied.

  8. Extraverted Children Are More Biased by Bowl Sizes than Introverts

    NARCIS (Netherlands)

    van Ittersum, Koert; Wansink, Brian

    2013-01-01

    Extraverted children are hypothesized to be most at risk for over-serving and overeating due to environmental cues - such as the size of dinnerware. A within-subject field study of elementary school students found that extraverted children served themselves 33.1% more cereal in larger bowls (16-oz)

  9. [Working conditions on public buses and common mental disorders among drivers and fare collectors: Greater Metropolitan Belo Horizonte, Minas Gerais State, Brazil, 2012].

    Science.gov (United States)

    Assunção, Ada Ávila; Silva, Luiz Sérgio; Silva, Luiz Sérgio da

    2013-12-01

    Common mental disorders (CMD) contribute to overall burden of disease. The current study aimed to describe the prevalence of CMD among a sample of bus drivers and fare collectors in Greater Metropolitan Belo Horizonte, Minas Gerais State, Brazil, and investigate whether traffic conditions and conditions inside buses were associated with the outcome. This non-probabilistic sample of 1,607 workers was estimated from the size of the effective workforce (n = 17,470). Face-to-face interviews used a digital questionnaire with online data processing. Overall prevalence of CMD was 23.6%. Bad traffic conditions lost statistical significance in the multivariate analysis, while higher income and adverse working conditions and inadequate safety remained associated with the outcome. Harmful behavior and vulnerable health situations were associated with CMD. This study of urban bus workers' health is a unique contribution that can provide backing for public policies targeting metropolitan populations.

  10. Simple and cost-effective fabrication of size-tunable zinc oxide architectures by multiple size reduction technique

    Directory of Open Access Journals (Sweden)

    Hyeong-Ho Park, Xin Zhang, Seon-Yong Hwang, Sang Hyun Jung, Semin Kang, Hyun-Beom Shin, Ho Kwan Kang, Hyung-Ho Park, Ross H Hill and Chul Ki Ko

    2012-01-01

    Full Text Available We present a simple size reduction technique for fabricating 400 nm zinc oxide (ZnO architectures using a silicon master containing only microscale architectures. In this approach, the overall fabrication, from the master to the molds and the final ZnO architectures, features cost-effective UV photolithography, instead of electron beam lithography or deep-UV photolithography. A photosensitive Zn-containing sol–gel precursor was used to imprint architectures by direct UV-assisted nanoimprint lithography (UV-NIL. The resulting Zn-containing architectures were then converted to ZnO architectures with reduced feature sizes by thermal annealing at 400 °C for 1 h. The imprinted and annealed ZnO architectures were also used as new masters for the size reduction technique. ZnO pillars of 400 nm diameter were obtained from a silicon master with pillars of 1000 nm diameter by simply repeating the size reduction technique. The photosensitivity and contrast of the Zn-containing precursor were measured as 6.5 J cm−2 and 16.5, respectively. Interesting complex ZnO patterns, with both microscale pillars and nanoscale holes, were demonstrated by the combination of dose-controlled UV exposure and a two-step UV-NIL.

  11. Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

    Science.gov (United States)

    Weber, Stephanie C; Brangwynne, Clifford P

    2015-03-01

    Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control.

  12. Nitrogen uptake by size-fractionated phytoplankton in mangrove waters

    Digital Repository Service at National Institute of Oceanography (India)

    Dham, V.V.; Wafar, M.V.M.; Heredia, A.M.

    .8 to 20 µm). In the present study, we report on these data and examine the relationships between phytoplankton size classes and the pattern of N nutrient utilisation. MATERIALS AND METHODS The Achara mangrove (16°12’ to 16°14’ N, 73°25’ to 73°30’ E), where...-incubation in order to avoid unrealistic uptake rates, especially in the smaller fraction (Dauchez et al. 1996). All the filtra- tions, including those for recovery of particulate matter for chl a and PON measurements, were done under low vacuum (<200 mm Hg). 15 N: 14...

  13. Resolution of Quadruplex Polymorphism by Size Exclusion Chromatography

    Science.gov (United States)

    Miller, M. Clarke; Trent, John O.

    2014-01-01

    This unit describes a method for the separation of quadruplex species formed from the same sequence via size exclusion chromatography (SEC). Polymorphism is inherent to quadruplex formation, and even relatively simple quadruplex forming sequences, such as the human telomere sequence d(GGG(TTAGGG)3), can form a myriad of possible configurations. High Performance Liquid Chromatography (HPLC), especially reverse phase and anion exchange methods, has been a mainstay of nucleic acids research and purification for many decades. We have applied these methods for the separation of individual quadruplex species formed in a mixture from the same parent sequence. PMID:21638270

  14. The MAN hydrogen propulsion system for city buses

    Energy Technology Data Exchange (ETDEWEB)

    Knorr, H.; Held, W.; Pruemm, W. [MAN Nutzfahrzeuge Aktiengesellschaft, Nuernberg (Germany); Ruediger, H. [Linde AG, Hoellriegelskreuth (Germany)

    1998-12-31

    MAN Nutzfahrzeuge Aktiengesellschaft has developed a hydrogen-powered bus as part of the Euro-Quebec Hydro-Hydrogen Pilot Project. The project is being sponsored by the European Union. The MAN hydrogen bus is based on a model SL standard-production city bus. The bus is driven by an internal combustion engine. The engine will run on either hydrogen or gasoline, to which end it has two independently-operating injection systems. The engine`s emission levels in both modes are well inside the applicable limits for commercial vehicles. The hydrogen is carried in the vehicle in liquid form at extremely low temperatures. The fuel tank system consists of three vacuum-insulated tanks, developed by Linde AG, who also developed the refueling system. A comprehensive safety concept has been compiled for the vehicle with the cooperation of TUV Bayern-Sachsen to ensure that the highest possible levels of safety are met. The bus has been accepted by TUV and has been in scheduled service since 1996. The vehicle has covered a distance of more than 10 000 km in the city of Erlangen without any safety-relevant incident or fault. (author)

  15. Highly Birefringent Photonic Crystal Fibers BUsing Asymmetric Core Design

    Institute of Scientific and Technical Information of China (English)

    Zhao Chun-Liu; Lu Chao; Yan Min; Wang Xiaoyan; Lou Junjun; Li Qin; Zhou Xiaoqun; Cai Qing; P.R.Chaudhuri

    2003-01-01

    We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.

  16. Intracellular micro-rheology probed by micron-sized wires.

    Science.gov (United States)

    Chevry, Loudjy; Colin, Rémy; Abou, Bérengère; Berret, Jean-François

    2013-09-01

    In the last decade, rapid advances have been made in the field of micro-rheology of cells and tissues. Given the complexity of living systems, there is a need for the development of new types of nano- and micron-sized probes, and in particular of probes with controlled interactions with the surrounding medium. In the present paper, we evaluate the use of micron-sized wires as potential probes of the mechanical properties of cells. The wire-based micro-rheology technique is applied to living cells such as murine fibroblasts and canine kidney epithelial cells. The mean-squared angular displacement of wires associated to their rotational dynamics is obtained as a function of the time using optical microscopy and image processing. It reveals a Brownian-like diffusive regime of the form Δψ(2)(t,L) ≈ t/L(3), where L denotes the wire length. This scaling suggests that an effective viscosity of the intracellular medium can be determined, and that in the range 1-10 μm it does not depend on the length scale over which it is measured.

  17. Poeciliid male mate preference is influenced by female size but not by fecundity

    Directory of Open Access Journals (Sweden)

    Luis R. Arriaga

    2013-08-01

    Full Text Available While female mate preference is very well studied, male preference has only recently begun to receive significant attention. Its existence is found in numerous taxa, but empirical research has mostly been limited to a descriptive level and does not fully address the factors influencing its evolution. We attempted to address this issue using preference functions by comparing the strength of male preference for females of different sizes in nine populations of four poeciliid species. Due to environmental constraints (water toxicity and surface versus cave habitat, females from these populations vary in the degree to which their size is correlated to their fecundity. Hence, they vary in how their size signals their quality as mates. Since female size is strongly correlated with fecundity in this subfamily, males were sequentially presented with conspecific females of three different size categories and the strength of their preference for each was measured. Males preferred larger females in all populations, as predicted. However, the degree to which males preferred each size category, as measured by association time, was not correlated with its fecundity. In addition, cave males discriminated against smaller females more than surface males. Assuming that male preference is correlated with female fitness, these results suggest that factors other than fecundity have a strong influence on female fitness in these species.

  18. Protein domain boundary prediction by combining support vector machine and domain guess by size algorithm

    Institute of Scientific and Technical Information of China (English)

    Dong Qiwen; Wang Xiaolong; Lin Lei

    2007-01-01

    Successful prediction of protein domain boundaries provides valuable information not only for the computational structure prediction of multi-domain proteins but also for the experimental structure determination. A novel method for domain boundary prediction has been presented, which combines the support vector machine with domain guess by size algorithm. Since the evolutional information of multiple domains can be detected by position specific score matrix, the support vector machine method is trained and tested using the values of position specific score matrix generated by PSI-BLAST. The candidate domain boundaries are selected from the output of support vector machine, and are then inputted to domain guess by size algorithm to give the final results of domain boundary prediction. The experimental results show that the combined method outperforms the individual method of both support vector machine and domain guess by size.

  19. Stabilization of electron beam spot size by self bias potential

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, T.J.T.; Moir, D.C.; Snell, C.M.; Kang, M.

    1998-12-31

    In high resolution flash x-ray imaging technology the electric field developed between the electron beam and the converter target is large enough to draw ions from the target surface. The ions provide fractional neutralization and cause the electron beam to focus radially inward, and the focal point subsequently moves upstream due to the expansion of the ion column. A self-bias target concept is proposed and verified via computer simulation that the electron charge deposited on the target can generate an electric potential, which can effectively limit the ion motion and thereby stabilize the growth of the spot size. A target chamber using the self bias target concept was designed and tested in the Integrated Test Stand (ITS). The authors have obtained good agreement between computer simulation and experiment.

  20. Determination of Size Distribution of Nano-particles by Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Yan XUE; Hai Ying YANG; Yong Tan YANG

    2005-01-01

    A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied. This method for the determination of size distribution was statistical.

  1. Narrow size distributed Ag nanoparticles grown by spin coating and thermal reduction: effect of processing parameters

    Science.gov (United States)

    Ansari, A. A.; Sartale, S. D.

    2016-08-01

    A simple method to grow uniform sized Ag nanoparticles with narrow size distribution on flat support (glass and Si substrates) via spin coating of Ag+ ions (AgNO3) solution followed by thermal reduction in H2 is presented. These grown nanoparticles can be used as model catalytic system to study size dependent oxygen reduction reaction (ORR) activity. Ag nanoparticles formation was confirmed by local surface plasmon resonance and x-ray photoelectron spectroscopy measurements. Influences of process parameters (revolution per minute (rpm), ramp and salt concentration) on grown Ag nanoparticles size, density and size uniformity are studied. With increase in rpm and ramp the size decreases and the particle number density increases, whereas the size dispersion improves. The catalytic activity of the grown Ag particles for ORR is studied and it is found that the catalytic performance is dependent on the size as well as the number density of the grown Ag nanoparticles.

  2. A facile synthesis of Te nanoparticles with binary size distribution by green chemistry.

    Science.gov (United States)

    He, Weidong; Krejci, Alex; Lin, Junhao; Osmulski, Max E; Dickerson, James H

    2011-04-01

    Our work reports a facile route to colloidal Te nanocrystals with binary uniform size distributions at room temperature. The binary-sized Te nanocrystals were well separated into two size regimes and assembled into films by electrophoretic deposition. The research provides a new platform for nanomaterials to be efficiently synthesized and manipulated.

  3. Direct and Indirect Evidence of Size-Selective Grazing on Pelagic Bacteria by Freshwater Nanoflagellates

    OpenAIRE

    Šimek, Karel; Thomas H. Chrzanowski

    1992-01-01

    Size-selective grazing of three heterotrophic nanoflagellates (with cell sizes of 21, 44, and 66 μm3) isolated from Lake Arlington, Texas was examined by using a natural mixture of fluorescence labelled lake bacteria. Sizes of ingested bacteria in food vacuoles were directly measured. Larger bacterial cells were ingested at a frequency much higher than that at which they occurred in the assemblage, indicating preferential flagellate grazing on the larger size classes within the lake bacteriop...

  4. Socorro County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  5. Rio Arriba County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  6. Cibola County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  7. Harding County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  8. Grant County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  9. Los Alamos County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  10. Roosevelt County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  11. Lea County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  12. Dona Ana County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  13. Valencia County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  14. Union County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  15. Curry County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  16. San Miguel County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  17. De Baca County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  18. Guadalupe County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  19. Bernalillo County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  20. San Juan County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  1. Sierra County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  2. Quay County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  3. Torrance County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  4. Mora County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  5. Catron County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  6. Santa Fe County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  7. Otero County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  8. Lincoln County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  9. Taos County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  10. Luna County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  11. Chaves County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  12. Eddy County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  13. Sandoval County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  14. Hidalgo County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  15. Colfax County Blocks, Average Household Size by Tenure (2010)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The once-a-decade decennial census was conducted in April 2010 by the U.S. Census Bureau. This count of every resident in the United States was mandated by Article...

  16. Laser Mode-Dependent Size of Plasma Zones Induced by Femtosecond Laser Pulses in Fused Silica

    Institute of Scientific and Technical Information of China (English)

    TANG Shan-Chun; JIANG Hong-Bing; LIU Yi; GONG Qi-Huang

    2008-01-01

    We carry out the numerical simulations of #emtosecond laser propagation with TEM00 mode, TEM10 mode and a beam combining both the modes in fused silica. It is found that the transverse size of plasma zones induced by laser pulses with the TEM10 mode is smaller than that induced by the TEMoo mode, while the longitudinal size is almost the same, and the saturated plasma density is higher. The transverse size, the longitudinal size and the ratio of the longitudinal to transverse size, for the beam combining both the modes, all could be reduced at the same time in comparison with the TEMoo mode under the same focusing conditions.

  17. Management by Objectives in the Medium-Sized Academic Library.

    Science.gov (United States)

    Martin, Ron G.

    Kearney State College Library in Nebraska implemented a management by objectives model in 1973. Following compilation of a statement of library aims in 1974, each department developed more specific objectives for the department that would support the aims statement. Within each plan was a role statement for the department, written objectives, and…

  18. Hydrogen propulsion systems for transit buses - results of operation in passenger transport

    Energy Technology Data Exchange (ETDEWEB)

    Hipp, E.; Gruber, C. [MAN Nutzfahrzeuge AG, Advance Development (Germany)

    2000-07-01

    Hydrogen is a source of energy which can in the long term play a major role in the energy and transport industries. It can be generated without using fossil products and against the background of ever shorter oil reserves it reduces the supply risks for transport and industry. Further advantages of hydrogen as a fuel for motor vehicles are its potential for reduction of greenhouse gases and pollutants from traffic. The hydrogen project at Munich airport aims to demonstrate the technical feasibility of autonomous hydrogen generation combined with operation of vehicles. MAN is participating in this project with two low-floor articulated buses with hydrogen engines. A further vehicles from Neoplan has also been fitted with MAN H{sub 2} driveline technology. The vehicles will be used for carrying passengers on the airport apron from early 1999 to the end of 2000 and are expected to supply important information on the use of hydrogen in day-to-day transport. (orig.)

  19. Genotype by environment interaction for litter size in pigs as quantified by reaction norms analysis

    DEFF Research Database (Denmark)

    Knap, P W; Su, G

    2008-01-01

    A Bayesian procedure was used to estimate linear reaction norms (i.e. individual G × E plots) on 297 518 litter size records of 121 104 sows, daughters of 2040 sires, recorded on 144 farms in North and Latin America, Europe, Asia and Australia. The method allowed for simultaneous estimation of all...... in the estimates of the additive genetic effect; the reaction norms model removes this confounding. The intercept estimates from the largest data subset show correlations with litter size estimated breeding values (EBV) from routine genetic evaluation (without reaction norms included) of 0.78 to 0.85 for sows...... with one to seven litter records, and 0.75 for sires. Hence, including reaction norms in genetic evaluation would increase the reliability of the EBV of young selection candidates without own performance or progeny data by considerably more than 100 × (1/0.75-1) = 33%. Reaction norm slope estimates turn...

  20. Tumor size measured by preoperative ultrasonography and postoperative pathologic examination in papillary thyroid carcinoma: relative differences according to size, calcification and coexisting thyroiditis.

    Science.gov (United States)

    Yoon, Young Hoon; Kwon, Ki Ryun; Kwak, Seo Young; Ryu, Kyeung A; Choi, Bobae; Kim, Jin-Man; Koo, Bon Seok

    2014-05-01

    Ultrasonography (US) is a useful diagnostic modality for evaluation of the size and features of thyroid nodules. Tumor size is a key indicator of the surgical extent of thyroid cancer. We evaluated the difference in tumor sizes measured by preoperative US and postoperative pathologic examination in papillary thyroid carcinoma (PTC). We reviewed the medical records of 172 consecutive patients, who underwent thyroidectomy for PTC treatment. We compared tumor size, as measured by preoperative US, with that in postoperative specimens. And we analyzed a number of factors potentially influencing the size measurement, including cancer size, calcification and coexisting thyroiditis. The mean size of the tumor measured by preoperative US was 11.4, and 10.2 mm by postoperative pathologic examination. The mean percentage difference (US-pathology/US) of tumor sizes measured by preoperative US and postoperative pathologic examination was 9.9 ± 19.3%, which was statistically significant (p 20.0 mm) and the presence of calcification or coexisting thyroiditis on the tumor size discrepancy between the two measurements was analyzed, the mean percentage differences according to tumor size (9.1 vs. 11.2% vs. 9.8%, p = 0.842), calcification (9.2 vs. 10.2%, p = 0.756) and coexisting thyroiditis (17.6 vs. 9.5%, p = 0.223) did not show statistical significance. Tumor sizes measured in postoperative pathology were ~90% of those measured by preoperative US in PTC; this was not affected by tumor size, the presence of calcification or coexisting thyroiditis. When the surgical extent of PTC treatment according to tumor size measured by US is determined, the relative difference between tumor sizes measured by preoperative US and postoperative pathologic examination should be considered.

  1. Size speed bias or size arrival effect-How judgments of vehicles' approach speed and time to arrival are influenced by the vehicles' size.

    Science.gov (United States)

    Petzoldt, Tibor

    2016-10-01

    Crashes at railway level crossings are a key problem for railway operations. It has been suggested that a potential explanation for such crashes might lie in a so-called size speed bias, which describes the phenomenon that observers underestimate the speed of larger objects, such as aircraft or trains. While there is some evidence that this size speed bias indeed exists, it is somewhat at odds with another well researched phenomenon, the size arrival effect. When asked to judge the time it takes an approaching object to arrive at a predefined position (time to arrival, TTA), observers tend to provide lower estimates for larger objects. In that case, road users' crossing decisions when confronted with larger vehicles should be rather conservative, which has been confirmed in multiple studies on gap acceptance. The aim of the experiment reported in this paper was to clarify the relationship between size speed bias and size arrival effect. Employing a relative judgment task, both speed and TTA estimates were assessed for virtual depictions of a train and a truck, using a car as a reference to compare against. The results confirmed the size speed bias for the speed judgments, with both train and truck being perceived as travelling slower than the car. A comparable bias was also present in the TTA estimates for the truck. In contrast, no size arrival effect could be found for the train or the truck, neither in the speed nor the TTA judgments. This finding is inconsistent with the fact that crossing behaviour when confronted with larger vehicles appears to be consistently more conservative. This discrepancy might be interpreted as an indication that factors other than perceived speed or TTA play an important role for the differences in gap acceptance between different types of vehicles.

  2. A facile synthesis of Tenanoparticles with binary size distribution by green chemistry

    Science.gov (United States)

    He, Weidong; Krejci, Alex; Lin, Junhao; Osmulski, Max E.; Dickerson, James H.

    2011-04-01

    Our work reports a facile route to colloidal Tenanocrystals with binary uniform size distributions at room temperature. The binary-sized Tenanocrystals were well separated into two size regimes and assembled into films by electrophoretic deposition. The research provides a new platform for nanomaterials to be efficiently synthesized and manipulated.Our work reports a facile route to colloidal Tenanocrystals with binary uniform size distributions at room temperature. The binary-sized Tenanocrystals were well separated into two size regimes and assembled into films by electrophoretic deposition. The research provides a new platform for nanomaterials to be efficiently synthesized and manipulated. Electronic supplementary information (ESI) available: Synthetic procedures, FTIR analysis, ED pattern, AFM image, and EPD current curve. See DOI: 10.1039/c1nr10025d

  3. Formation and characterization of varied size germanium nanocrystals by electron microscopy, Raman spectroscopy, and photoluminescence

    DEFF Research Database (Denmark)

    Ou, Haiyan; Ou, Yiyu; Liu, Chuan;

    2011-01-01

    and crystallization. The samples of different size Ge nanocrystals embedded in the SiO2 matrix were characterized by Raman spectroscopy and photoluminescence. Interplayed size and strain effect of Ge nanocystals was demonstrated by Raman spectroscopy after excluding the thermal effect with proper excitation laser...

  4. Effect of pore size on gas resistance of nanofiber membrane by the bubble electrospinning

    Directory of Open Access Journals (Sweden)

    Shen Jing

    2015-01-01

    Full Text Available This paper explores the influence of pore size on gas resistance by comparing micron non-woven and nanofiber membrane. The result shows that membrane with a higher filtration and lower gas resistance can be received by controlling the pore size of nanofiber membrane.

  5. Control over Particle Size Distribution by Autoclaving Poloxamer-Stabilized Trimyristin Nanodispersions.

    Science.gov (United States)

    Göke, Katrin; Roese, Elin; Arnold, Andreas; Kuntsche, Judith; Bunjes, Heike

    2016-09-06

    Lipid nanoparticles are under investigation as delivery systems for poorly water-soluble drugs. The particle size in these dispersions strongly influences important pharmaceutical properties like biodistribution and drug loading capacity; it should be below 500 nm for direct injection into the bloodstream. Consequently, small particles with a narrow particle size distribution are desired. Hitherto, there are, however, only limited possibilities for the preparation of monodisperse, pharmaceutically relevant dispersions. In this work, the effect of autoclaving at 121 °C on the particle size distribution of lipid nanoemulsions and -suspensions consisting of the pharmaceutically relevant components trimyristin and poloxamer 188 was studied. Additionally, the amount of emulsifier needed to stabilize both untreated and autoclaved particles was assessed. In our study, four dispersions of mean particle sizes from 45 to 150 nm were prepared by high-pressure melt homogenization. The particle size distribution before and after autoclaving was characterized using static and dynamic light scattering, differential scanning calorimetry, and transmission electron microscopy. Asymmetrical flow field-flow fractionation was used for particle size distribution analyses and for the determination of free poloxamer 188. Upon autoclaving, the mean particle size increased to up to 200 nm, but not proportionally to the initial size. At the same time, the particle size distribution width decreased remarkably. Heat treatment thus seems to be a promising approach to achieve the desired narrow particle size distribution of such dispersions. Related to the lipid content, suspension particles needed more emulsifier for stabilization than emulsion droplets, and smaller particles more than larger ones.

  6. Design of a Mobile Low-Cost Sensor Network Using Urban Buses for Real-Time Ubiquitous Noise Monitoring.

    Science.gov (United States)

    Alsina-Pagès, Rosa Ma; Hernandez-Jayo, Unai; Alías, Francesc; Angulo, Ignacio

    2016-12-29

    One of the main priorities of smart cities is improving the quality of life of their inhabitants. Traffic noise is one of the pollutant sources that causes a negative impact on the quality of life of citizens, which is gaining attention among authorities. The European Commission has promoted the Environmental Noise Directive 2002/49/EC (END) to inform citizens and to prevent the harmful effects of noise exposure. The measure of acoustic levels using noise maps is a strategic issue in the END action plan. Noise maps are typically calculated by computing the average noise during one year and updated every five years. Hence, the implementation of dynamic noise mapping systems could lead to short-term plan actions, besides helping to better understand the evolution of noise levels along time. Recently, some projects have started the monitoring of noise levels in urban areas by means of acoustic sensor networks settled in strategic locations across the city, while others have taken advantage of collaborative citizen sensing mobile applications. In this paper, we describe the design of an acoustic low-cost sensor network installed on public buses to measure the traffic noise in the city in real time. Moreover, the challenges that a ubiquitous bus acoustic measurement system entails are enumerated and discussed. Specifically, the analysis takes into account the feature extraction of the audio signal, the identification and separation of the road traffic noise from urban traffic noise, the hardware platform to measure and process the acoustic signal, the connectivity between the several nodes of the acoustic sensor network to store the data and, finally, the noise maps' generation process. The implementation and evaluation of the proposal in a real-life scenario is left for future work.

  7. Uptake characteristics of liposomes by rat alveolar macrophages: influence of particle size and surface mannose modification.

    Science.gov (United States)

    Chono, Sumio; Tanino, Tomoharu; Seki, Toshinobu; Morimoto, Kazuhiro

    2007-01-01

    The influence of particle size and surface mannose modification on the uptake of liposomes by alveolar macrophages (AMs) was investigated in-vitro and in-vivo. Non-modified liposomes of five different particle sizes (100, 200, 400, 1000 and 2000 nm) and mannosylated liposomes with 4-aminophenyl-alpha-D-mannopyranoside (particle size 1000 nm) were prepared, and the uptake characteristics by rat AMs in-vitro and in-vivo were examined. The uptake of non-modified liposomes by rat AMs in-vitro increased with an increase in particle size over the range of 100-1000 nm, and became constant at over 1000 nm. The uptake of non-modified liposomes by AMs after pulmonary administration to rats in-vivo increased with an increase in particle size in the range 100-2000 nm. The uptake of mannosylated liposomes (particle size 1000 nm) by rat AMs both in-vitro and in-vivo was significantly greater than that of non-modified liposomes (particle size 1000 nm). The results indicate that the uptake of liposomes by rat AMs is dependent on particle size and is increased by surface mannose modification.

  8. ON ESTIMATION AND HYPOTHESIS TESTING OF THE GRAIN SIZE DISTRIBUTION BY THE SALTYKOV METHOD

    Directory of Open Access Journals (Sweden)

    Yuri Gulbin

    2011-05-01

    Full Text Available The paper considers the problem of validity of unfolding the grain size distribution with the back-substitution method. Due to the ill-conditioned nature of unfolding matrices, it is necessary to evaluate the accuracy and precision of parameter estimation and to verify the possibility of expected grain size distribution testing on the basis of intersection size histogram data. In order to review these questions, the computer modeling was used to compare size distributions obtained stereologically with those possessed by three-dimensional model aggregates of grains with a specified shape and random size. Results of simulations are reported and ways of improving the conventional stereological techniques are suggested. It is shown that new improvements in estimating and testing procedures enable grain size distributions to be unfolded more efficiently.

  9. Production of various sizes and some properties of beryllium pebbles by the rotating electrode method

    Energy Technology Data Exchange (ETDEWEB)

    Iwadachi, T.; Sakamoto, N.; Nishida, K. [NGK Insulators Ltd., Nagoya (Japan); Kawamura, H.

    1998-01-01

    The particle size distribution of beryllium pebbles produced by the rotating electrode method was investigated. Particle size depends on some physical properties and process parameters, which can practicaly be controlled by varying electrode angular velocities. The average particle sizes produced were expressed by the hyperbolic function with electrode angular velocity. Particles within the range of 0.3 and 2.0 mm in diameter are readily produced by the rotating electrode method while those of 0.2 mm in diameter are also fabricable. Sphericity and surface roughness were good in each size of pebble. Grain sizes of the pebbles are 17 {mu} m in 0.25 mm diameter pebbles and 260 {mu} m in 1.8 mm diameter pebbles. (author)

  10. Intriguing structures and magic sizes of heavy noble metal nanoclusters around size 55 governed by relativistic effect and covalent bonding

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X. J.; Xue, X. L.; Jia, Yu [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Guo, Z. X. [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Department of Chemistry and London Centre for Nanotechnology, University College London, London WC1H (United Kingdom); Li, S. F., E-mail: sflizzu@zzu.edu.cn [International Laboratory for Quantum Functional Materials of Henan and School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001 (China); ICQD, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhenyu, E-mail: zhangzy@ustc.edu.cn [ICQD, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Gao, Y. F., E-mail: ygao7@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    2015-11-07

    Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. By means of first-principles calculations within density functional theory, we find that heavy noble metal Pt{sub N} nanoclusters around the size N = 55 begin to prefer an open configuration, rather than previously reported close-packed icosahedron or core-shell structures. Particularly, for Pt{sub N}, the widely supposed icosahedronal magic cluster is changed to a three-atomic-layered structure with D{sub 6h} symmetry, which can be well addressed by our recently established generalized Wulff construction principle (GWCP). However, the magic number of Pt{sub N} clusters around 55 is shifted to a new odd number of 57. The high symmetric three-layered Pt{sub 57} motif is mainly stabilized by the enhanced covalent bonding contributed by both spin-orbital coupling effect and the open d orbital (5d{sup 9}6s{sup 1}) of Pt, which result in a delicate balance between the enhanced Pt–Pt covalent bonding of the interlayers and negligible d dangling bonds on the cluster edges. These findings about Pt{sub N} clusters are also applicable to Ir{sub N} clusters, but qualitatively different from their earlier neighboring element Os and their later neighboring element Au. The magic numbers for Os and Au are even, being 56 and 58, respectively. The findings of the new odd magic number 57 are the important supplementary of the recently established GWCP.

  11. Urban transportation system optimum: The effect of accounting for the interaction of buses and cars

    Directory of Open Access Journals (Sweden)

    Cristian Angelo Guevara

    2011-01-01

    Full Text Available En este trabajo se usa un método iterativo para calcular tarifas Pigouvianascuando las vías son compartidas por autos y buses. Se comparan escenarios en los cuales: 1 la tarifa es calculada considerando sólo la externalidad sobre otros vehículos; 2 la tarifa considera además la externalidad sobre los pasajeros de los vehículos; 3 no se aplican tarifas; y 4 no se aplican tarifas, pero algunas pistas son reservadas para el uso exclusivo de buses. El método es aplicado primero a un modelo idealizado que considera homogenidad de la demanda y cierto grado de heterogenidad en la oferta. Luego el método es aplicado en un experimento con datos reales basado en un modelo simultáneo de cuatro etapas calibrado para la ciudad de Santiago, Chile. Todos los experimentos muestran que cuando se considera la externalidad sobre los pasajeros de los vehículos, las tarifas Pigouvianas crecen sustancialmente en las vías de uso mixto, lo cual se traduce en un menor flujo de automóviles en dichas vías. Por otro lado, las simulaciones con el modelo idealizado muestran que el efecto de la reservación de pistas depende fuertemente del diseño considerado. Respecto de la tarificación Pigouviana, el experimento con datos reales muestra, sorprendentemente, que dicha política resultaría ser inferior a un escenario en el cual no se aplican tarifas. Este resultado podría atribuirse a: 1 que el modelo con datos reales representa una situación de equilibrio general y en cambio las tarifas Pigouvianas se calculan usando un enfoque de equilibrio parcial; 2 limitaciones de modelación en el experimento con datos reales; o 3 una manifestación del contraejemplo de Coase para los impuestos Pigouvianos. El artículo termina discutiendo el impacto de estos resultados en el análisis de políticas de transporte urbano.

  12. Direct and indirect evidence of size-selective grazing on pelagic bacteria by freshwater nanoflagellates.

    Science.gov (United States)

    Simek, K; Chrzanowski, T H

    1992-11-01

    Size-selective grazing of three heterotrophic nanoflagellates (with cell sizes of 21, 44, and 66 mum) isolated from Lake Arlington, Texas was examined by using a natural mixture of fluorescence labelled lake bacteria. Sizes of ingested bacteria in food vacuoles were directly measured. Larger bacterial cells were ingested at a frequency much higher than that at which they occurred in the assemblage, indicating preferential flagellate grazing on the larger size classes within the lake bacterioplankton. Water samples were collected biweekly from June through September, 1989, fractionated by filtration, and incubated for 40 h at in situ temperatures. The average bacterial size was always larger in water which was passed through 1-mum-pore-size filters (1-mum-filtered water) (which was predator free) than in 5-mum-filtered water (which contained flagellates only) or in unfiltered water (in which all bacterivores were present). The increase of bacterial-cell size in 1-mum-filtered water was caused by a shift in the size structure of the bacterioplankton population. Larger cells became more abundant in the absence of flagellate grazing.

  13. The neural processing of musical instrument size information in the brain investigated by magnetoencephalography

    Science.gov (United States)

    Rupp, Andre; van Dinther, Ralph; Patterson, Roy D.

    2005-04-01

    The specific cortical representation of size was investigated by recording auditory evoked fields (AEFs) elicited by changes of instrument size and pitch. In Experiment 1, a French horn and one scaled to double the size played a three note melody around F3 or its octave, F4. Many copies of these four melodies were played in random order and the AEF was measured continuously. A similar procedure was applied to saxophone sounds in a separate run. In Experiment 2, the size and type of instrument (French horn and saxophone) were varied without changing the octave. AEFs were recorded in five subjects using magnetoencephalography and evaluated by spatio-temporal source analysis with one equivalent dipole in each hemisphere. The morphology of the source waveforms revealed that each note within the melody elicits a well-defined P1-N1-P2 AEF-complex with adaptation for the 2nd and 3rd note. At the transition of size, pitch, or both, a larger AEF-complex was evoked. However, size changes elicited a stronger N1 than pitch changes. Furthermore, this size-related N1 enhancement was larger for French horn than saxophone. The results indicate that the N1 plays an important role in the specific representation of instrument size.

  14. Calibration of radiographs by a reference metal ball affects preoperative selection of implant size.

    Science.gov (United States)

    Schropp, Lars; Stavropoulos, Andreas; Gotfredsen, Erik; Wenzel, Ann

    2009-12-01

    The aim was to evaluate the impact of a reference ball for calibration of periapical and panoramic radiographs on preoperative selection of implant size for three implant systems. Presurgical digital radiographs (70 panoramic, 43 periapical) from 70 patients scheduled for single-tooth implant treatment, recorded with a metal ball placed in the edentulous area, were evaluated by three observers with the intent to select the appropriate implant size. Four reference marks corresponding to the margins of the metal ball were manually placed on the digital image by means of computer software. Additionally, an implant with proper dimensions for the respective site was outlined by manually placing four reference marks. The diameter of the metal ball and the unadjusted length and width of the implant were calculated. Implant size was adjusted according to a "standard" calibration method (SCM; magnification factor 1.25 in panoramic images and 1.05 in periapical images) and according to a reference ball calibration method (RCM; true magnification). Based on the unadjusted as well as the adjusted implant dimensions, the implant size was selected among those available in a given implant system. For periapical radiographs, when comparing SCM and RCM with unadjusted implant dimensions, implant size changed in 42% and 58%, respectively. When comparing SCM and RCM, implant size changed in 24%. For panoramic radiographs, comparing SCM and RCM changed implant size in 48%. The use of a reference metal ball for calibration of periapical and panoramic radiographs when selecting implant size during treatment planning might be advantageous.

  15. Analysis of submicron-sized niflumic acid crystals prepared by electrospray crystallization.

    Science.gov (United States)

    Ambrus, Rita; Radacsi, Norbert; Szunyogh, Tímea; van der Heijden, Antoine E D M; Ter Horst, Joop H; Szabó-Révész, Piroska

    2013-03-25

    Interest in submicron-sized drug particles has emerged from both laboratory and industrial perspectives in the last decade. Production of crystals in the nano size scale offers a novel way to particles for drug formulation solving formulation problems of drugs with low solubility in class II of the Biopharmaceutical Classification System. In this work niflumic acid nanoparticles with a size range of 200-800nm were produced by the novel crystallization method, electrospray crystallization. Their properties were compared to those from evaporative and anti-solvent crystallizations, using the same organic solvent, acetone. There is a remarkable difference in the product crystal size depending on the applied methods. The size and morphology were analyzed by scanning electron microscopy and laser diffraction. The structure of the samples was investigated using differential scanning calorimetry, Fourier-transformed infrared spectroscopy and X-ray powder diffraction. The particles produced using electrospray crystallization process were probably changing from amorphous to crystalline state after the procedure.

  16. Impact of variable body size on pedestrian dynamics by heuristics-based model

    Science.gov (United States)

    Guo, Ning; Hu, Mao-Bin; Jiang, Rui

    2017-01-01

    In the real world, pedestrians can arch the shoulders or rotate their bodies actively to across the narrow space. The method is helpful to reduce the effective size of the body. In this paper, the impact of variable body size on the direction choice has been investigated by an improved heuristic-based model. In the model, it is assumed that the cost of adjusting body size is a factor in the process to evaluate the optimal direction. In a typical simulation scenario, the pedestrian reluctant to adjust body size will pass by the blocks. On the contrary, the pedestrian caring little about body size will traverse through the exit. There is a direction-choice change behavior between bypass and traverse considering block width and the initial location of the pedestrian.

  17. Brain size regulations by cbp haploinsufficiency evaluated by in-vivo MRI based volumetry.

    Science.gov (United States)

    Ateca-Cabarga, Juan C; Cosa, Alejandro; Pallarés, Vicente; López-Atalaya, José P; Barco, Ángel; Canals, Santiago; Moratal, David

    2015-11-06

    The Rubinstein-Taybi Syndrome (RSTS) is a congenital disease that affects brain development causing severe cognitive deficits. In most cases the disease is associated with dominant mutations in the gene encoding the CREB binding protein (CBP). In this work, we present the first quantitative analysis of brain abnormalities in a mouse model of RSTS using magnetic resonance imaging (MRI) and two novel self-developed automated algorithms for image volumetric analysis. Our results quantitatively confirm key syndromic features observed in RSTS patients, such as reductions in brain size (-16.31%, p brain tissues in a region by region basis between cbp(+/-) and cbp(+/+) littermates, we found that cbp haploinsufficiency is specifically associated with significant reductions in prosencephalic tissue, such us in the olfactory bulb and neocortex, whereas regions evolved from the embryonic rhombencephalon were spared. Despite the large volume reductions, the proportion between gray-, white-matter and cerebrospinal fluid were conserved, suggesting a role of CBP in brain size regulation. The commonalities with holoprosencephaly and arhinencephaly conditions suggest the inclusion of RSTS in the family of neuronal migration disorders.

  18. An analysis of the size distribution of Italian firms by age

    Science.gov (United States)

    Cirillo, Pasquale

    2010-02-01

    In this paper we analyze the size distribution of Italian firms by age. In other words, we want to establish whether the way that the size of firms is distributed varies as firms become old. As a proxy of size we use capital. In [L.M.B. Cabral, J. Mata, On the evolution of the firm size distribution: Facts and theory, American Economic Review 93 (2003) 1075-1090], the authors study the distribution of Portuguese firms and they find out that, while the size distribution of all firms is fairly stable over time, the distributions of firms by age groups are appreciably different. In particular, as the age of the firms increases, their size distribution on the log scale shifts to the right, the left tails becomes thinner and the right tail thicker, with a clear decrease of the skewness. In this paper, we perform a similar analysis with Italian firms using the CEBI database, also considering firms’ growth rates. Although there are several papers dealing with Italian firms and their size distribution, to our knowledge a similar study concerning size and age has not been performed yet for Italy, especially with such a big panel.

  19. Effect the Grain Size on the Polymer Matrix Composites Reinforced by Reenia Particles

    Directory of Open Access Journals (Sweden)

    Kdhim khaion kahlol

    2013-01-01

    Full Text Available Synthetic polymers such as polyurethane are used widely in the field of biomedical applications such as implants or part of implant systems.This paper focuses on the preparation of base polymer matrix composite materials by (Hand Lay-Up method, and studying the effect of selected grain size (32, 53, 63, 75, and 90 µm of (Reenia particles on some properties of the prepared composite.Mechanical tests were used to evaluate the prepared system (Tensile, Compression, Impact, and Hardness tests, and a physical test of (Water absorption %, and all tests were accomplished at room temperature.Where results showed tensile test (maximum tensile strength and modulus of elasticity high at small grain size while the percentage of elongation decreased with increasing size. As the compressive strength increased with small grain size. And also the values of hardness and fracture energy affected by particle size where the hardness and fracture energy increased at small particles size of compared to larger particles size. While the percentage of water absorption increased at large particle size.In general the results showed clear improvement in properties and maximum values which get it of tensile strength, Modulus of elasticity, elongation percentage, compression strength, fracture energy, hardness and water absorption were as follows ((34.8 MPa, (10%, (268 N/mm2, ( 54.2 MPa,( o.408 J, (78.9 Shor (D, (0.2668 % at using (32µm except water absorption was at (90µm .

  20. High sintering resistance of size-selected platinum cluster catalysts by suppressed ostwald ripening

    DEFF Research Database (Denmark)

    Wettergren, Kristina; Schweinberger, Florian F.; Deiana, Davide;

    2014-01-01

    Employing rationally designed model systems with precise atom-by-atom particle size control, we demonstrate by means of combining noninvasive in situ indirect nanoplasmonic sensing and ex situ scanning transmission electron microscopy that monomodal size-selected platinum cluster catalysts...... on different supports exhibit remarkable intrinsic sintering resistance even under reaction conditions. The observed stability is related to suppression of Ostwald ripening by elimination of its main driving force via size-selection. This study thus constitutes a general blueprint for the rational design...

  1. Wage differentials by firm size: the efficiency wage test in a developing country

    Directory of Open Access Journals (Sweden)

    Tatiane Almeida de Menezes

    2014-03-01

    Full Text Available Using data from the Brazilian Labor Monthly Survey (PME/ IBGE for the years of 2006 and 2007, the paper investigates if the wage differential by firm size in Brazil can be explained by the predictions of the Efficiency Wage Theory. It is adopted a Switching Regression Model to estimate if large size companies pay a higher wage premium for dispended labor effort, as compared to smaller enterprises. The results prove the EW predictions since they evidence positive relationships between wages and labor effort, schooling and longer job duration. However, such findings are not sufficient to explain the existence of wage differentials by firm size in the Brazilian labor market.

  2. How to Cut Costs by Saving School Bus Fuel.

    Science.gov (United States)

    Seiff, Hank

    A program started in Washington County, Maryland in 1980 has been successful in saving school bus fuel and bringing down transportation costs incurred by its fleet of 200 buses. Driver training and motivation, as well as a partial transfer to diesel buses, are at the heart of the program. The drivers are taught five fuel saving techniques: cut…

  3. Can adult and juvenile European rabbits be differentiated by their pellet sizes?

    Science.gov (United States)

    Delibes-Mateos, Miguel; Rouco, Carlos; Villafuerte, Rafael

    2009-03-01

    Recently, a new method for differentiating juvenile and adult rabbits based on faecal pellet size was published. According to this method, pellets >6 mm diameter are inferred to be deposited by adults, while those kittens. In this study, we designed a simple experiment to test the accuracy of this methodology. Twelve adult rabbits were housed in individual outdoor cages and their pellets were removed every day for 10 consecutive days. Pellets were separated using a sieve according to their size and counted. Results showed that adult rabbits produce pellets >6 mm diameter in the same proportion as those 6 mm, whereas others deposit mostly pellets <6 mm in size. Our findings demonstrate that pellet size is unsuitable for aging wild rabbits. Field biologists should therefore be cautious when employing the pellet size method of age determination in other wild animals in the absence of validating studies.

  4. Optimizing human embryonic stem cells differentiation efficiency by screening size-tunable homogenous embryoid bodies.

    Science.gov (United States)

    Moon, Sung-Hwan; Ju, Jongil; Park, Soon-Jung; Bae, Daekyeong; Chung, Hyung-Min; Lee, Sang-Hoon

    2014-07-01

    Human embryonic stem cells (hESCs) are generally induced to differentiate by forming spherical structures termed embryoid bodies (EBs) in the presence of soluble growth factors. hEBs are generated by suspending small clumps of hESC colonies; however, the resulting hEBs are heterogeneous because this method lacks the ability to control the number of cells in individual EBs. This heterogeneity affects factors that influence differentiation such as cell-cell contact and the diffusion of soluble factors, and consequently, the differentiation capacity of each EB varies. Here, we fabricated size-tunable concave microwells to control the physical environment, thereby regulating the size of EBs formed from single hESCs. Defined numbers of single hESCs were forced to aggregate and generate uniformly sized EBs with high fidelity, and the size of the EBs was controlled using concave microwells of different diameters. Differentiation patterns in H9- and CHA15-hESCs were affected by EB size in both the absence and presence of growth factors. By screening EB size in the presence of various BMP4 concentrations, a two-fold increase in endothelial cell differentiation was achieved. Because each hESC line has unique characteristics, the findings of this study demonstrate that concave microwells could be used to screen different EB sizes and growth factor concentrations to optimize differentiation for each hESC line.

  5. Improvement of Biohydrogen Production under Increased the Reactor Size by C. acetobutylicum NCIMB 13357

    Directory of Open Access Journals (Sweden)

    Hisham S. Alshiyab

    2009-01-01

    Full Text Available Problem statement: One of the main factors influenced the bacterial productivity and total yield of hydrogen is the partial pressure of produced gas. A novel solution to enhance the bacterial productivity was through reduction of gas pressure. Approach: Increasing the reactor size showed to enhance the bacterial production of hydrogen. Results: The technique of increasing reactor size resulted to enhance the hydrogen yield (YP/S from 269 mL g-1 glucose utilized to maximum yield of 448 mL g-1 glucose utilized by using 125 mL and 2 L reactor size respectively. The hydrogen productivity was also enhanced from 71 mL-1 h-1 to maximum of 91 mL L-1 h-1 was obtained by using 125 mL and 1 L reactor size respectively. Biomass concentration was enhanced from 1.03 g L-1 to maximum of 1.68 g L-1 by using 125 mL and 2 L reactor size were used respectively, hydrogen yield per biomass (YP/X of 267 mL g-1 L-1, biomass per substrate utilized (YX/S of 0.336 and produced hydrogen in gram per gram of glucose utilized (YH2/s of 0.04 when 2 L reactor size was employed. Conclusion: By using bigger reactor size, the effect of gaseous products in fermentation medium was reduced and enhanced both bacterial productivity and biomass concentration.

  6. Small-for-Size Liver Transplantation Increases Pulmonary Injury in Rats: Prevention by NIM811

    Directory of Open Access Journals (Sweden)

    Qinlong Liu

    2012-01-01

    Full Text Available Pulmonary complications after liver transplantation (LT often cause mortality. This study investigated whether small-for-size LT increases acute pulmonary injury and whether NIM811 which improves small-for-size liver graft survival attenuates LT-associated lung injury. Rat livers were reduced to 50% of original size, stored in UW-solution with and without NIM811 (5 μM for 6 h, and implanted into recipients of the same or about twice the donor weight, resulting in half-size (HSG and quarter-size grafts (QSG, respectively. Liver injury increased and regeneration was suppressed after QSG transplantation as expected. NIM811 blunted these alterations >75%. Pulmonary histological alterations were minimal at 5–18 h after LT. At 38 h, neutrophils and monocytes/macrophage infiltration, alveolar space exudation, alveolar septal thickening, oxidative/nitrosative protein adduct formation, and alveolar epithelial cell/capillary endothelial apoptosis became overt in the lungs of QSG recipients, but these alterations were mild in full-size and HSG recipients. Liver pretreatment with NIM811 markedly decreased pulmonary injury in QSG recipients. Hepatic TNFα and IL-1β mRNAs and pulmonary ICAM-1 expression were markedly higher after QSG transplantation, which were all decreased by NIM811. Together, dysfunctional small-for-size grafts produce toxic cytokines, leading to lung inflammation and injury. NIM811 decreased toxic cytokine formation, thus attenuating pulmonary injury after small-for-size LT.

  7. Size and shape controllable preparation of graphene sponge by freezing, lyophilizing and reducing in container

    Institute of Scientific and Technical Information of China (English)

    ZHAO LianQin; YU BaoWei; ZHANG XiaoLiang; WU RuiHan; LIU XiaoYang; LIAO Rong; YANG ShengTao

    2016-01-01

    Graphene sponge (GS) is a porous 3D structure of graphene.Although hydrothermal reduction,chemical vapor deposition,solution reduction and high temperature annealing could be used for the preparation of GS,the size and shape cannot be well controlled.Herein,we reported a facile method to prepare GS under mild condition in a size and shape controllable way.Graphene oxide was lyophilized to form the spongy structure and reduced by steamy hydrazine hydrate to produce GS.The size and shape of GS prepared were nearly identical to that of the container.The reduction degree of GS could be regulated by the reduction temperature and time.

  8. Ammonium assimilation and regeneration by size-fractionated plankton in permanently well-mixed temperate waters

    Digital Repository Service at National Institute of Oceanography (India)

    LeCorre, P.; Wafar, M.V.M.; Helguen, S.L.; Maguer, J.F.

    report on the seasonal variations in ammonium assimilation and regeneration by size-fractionated plankton at a coastal station in the perma- nently well-mixed waters of the English Channel. We answer two questions: which size classes are important... assimilation and regeneration by size-fractionated plankton were measured for 1 year at a coastal station in the permanently well-mixed waters of the western English Channel. The lowest assimilation and regeneration rates (<1 ng-at N1"' h~') were in winter...

  9. A PSO-DP Based Method to Determination of the Optimal Number, Location, and Size of FACTS Devices in Power Systems

    Directory of Open Access Journals (Sweden)

    SHOJAEIAN, S.

    2014-02-01

    Full Text Available The presence of reactive component of current in transmission lines causes adverse impact on the network, including power losses, reduction of line capacity, and voltage drop. These adverse impacts can be reduced by using the first or second generation of FACTS devices. In this paper, these adverse impacts can be reduced optimally by using one of the modern optimization techniques, i.e., particle swarm optimization algorithm (PSO algorithm. By using this algorithm, the optimal size of the static VAr compensator (FACTS devices in a 30 bus IEEE test system is determined. At first, the load flow equations of the 30 bus IEEE test system is defined in the MATLAB software by means of dynamic programming method, and the number of SVCs will be determined by using the system sensitivity function (power losses and the sum of buses voltage drop square; then, the optimal sizes of the FACTS devices is obtained by means of PSO algorithm.

  10. Sensitive and predictable separation of microfluidic droplets by size using in-line passive filter.

    Science.gov (United States)

    Ding, Ruihua; Ung, W Lloyd; Heyman, John A; Weitz, David A

    2017-01-01

    Active manipulation of droplets is crucial in droplet microfluidics. However, droplet polydispersity decreases the accuracy of active manipulation. We develop a microfluidic "droplet filter" that accurately separates droplets by size. The droplet filter has a sharp size cutoff and is capable of distinguishing droplets differing in volume by 20%. A simple model explains the behavior of the droplets as they pass through the filter. We show application of the filter in improving dielectric sorting efficiency.

  11. Grain size effect of monolayer MoS2 transistors characterized by second harmonic generation mapping

    KAUST Repository

    Lin, Chih-Pin

    2015-08-27

    We investigated different CVD-synthesized MoS2 films, aiming to correlate the device characteristics with the grain size. The grain size of MoS2 can be precisely characterized through nondestructive second harmonic generation mapping based on the degree of inversion symmetry. The devices with larger grains at the channel region show improved on/off current ratio, which can be explained by the less carrier scattering caused by the grain boundaries.

  12. Fatigue-related crashes involving express buses in Malaysia: will the proposed policy of banning the early-hour operation reduce fatigue-related crashes and benefit overall road safety?

    Science.gov (United States)

    Mohamed, Norlen; Mohd-Yusoff, Mohammad-Fadhli; Othman, Ilhamah; Zulkipli, Zarir-Hafiz; Osman, Mohd Rasid; Voon, Wong Shaw

    2012-03-01

    Fatigue-related crashes have long been the topic of discussion and study worldwide. The relationship between fatigue-related crashes and time of day is well documented. In Malaysia, the possibility of banning express buses from operating during the early-hours of the morning has emerged as an important consideration for passenger safety. This paper highlights the findings of an impact assessment study. The study was conducted to determine all possible impacts prior to the government making any decision on the proposed banning. This study is an example of a simple and inexpensive approach that may influence future policy-making process. The impact assessment comprised two major steps. The first step involved profiling existing operation scenarios, gathering information on crashes involving public express buses and stakeholders' views. The second step involved a qualitative impact assessment analysis using all information gathered during the profiling stage to describe the possible impacts. Based on the assessment, the move to ban early-hour operations could possibly result in further negative impacts on the overall road safety agenda. These negative impacts may occur if the fundamental issues, such as driving and working hours, and the need for rest and sleep facilities for drivers, are not addressed. In addition, a safer and more accessible public transportation system as an alternative for those who choose to travel at night would be required. The proposed banning of early-hour operations is also not a feasible solution for sustainability of express bus operations in Malaysia, especially for those operating long journeys. The paper concludes by highlighting the need to design a more holistic approach for preventing fatigue-related crashes involving express buses in Malaysia.

  13. The Nano-Sized In2O3 Powder Synthesis by Sol-Gel Method

    Institute of Scientific and Technical Information of China (English)

    潘庆谊; 程知萱; 等

    2002-01-01

    Wiwh InCl3·4H2O being used as raw materials,the precursor of nano-sized In2O3 powder was prepared by hydrolysis,peptization and gelation of InCl3·4H2O.After calcination,nano-sized In2O3 powder was obtained.The powder was characterized by thermogravimetric and differential thermal analysis(TG-DTA).X-ray diffractometry(XRD)and transmission electron microscopy(TEM),respectively,Calculation revealed that the mean crystablline size increased with increasing the calcination temperature,but crystal lattice distortion rate decreased with the increasing in the average crystalline size.This indicated that the smaller the particle size,the bigger the crystal lattice distortion,the worse the crystal growing.The activation energies for growth of nano-sized In2O3 were calculated to be 4.75kJ·mol-1 at the calcination temperature up tp 500℃ and 66.40kJ· mol-1 at the calcination temperature over 600℃.TEM photos revealed that the addition of the chemical additive(OP-10)greatly influenced the morphology and size of In2O3 particles.

  14. Size control by rate control in colloidal PbSe quantum dot synthesis

    Science.gov (United States)

    Čapek, Richard Karel; Yanover, Dianna; Lifshitz, Efrat

    2015-03-01

    A recently demonstrated approach to control the size of colloidal nanoparticles, ``size control by rate control'', which was validated on the examples of colloidal CdSe- and CdS-quantum dot (CQD) synthesis, appears to be a general strategy for designing technically applicable CQD-syntheses. The ``size control by rate control'' concept allows full-yield syntheses of ensembles of CQDs with different sizes by tuning the solute formation rate. In this work, we extended this strategy to dialkylphosphine enhanced hot-injection synthesis of PbSe-CQDs. Furthermore, we provide new insight into the reaction mechanism of dialkylphosphine enhancement in TOPSe based CQD-syntheses.A recently demonstrated approach to control the size of colloidal nanoparticles, ``size control by rate control'', which was validated on the examples of colloidal CdSe- and CdS-quantum dot (CQD) synthesis, appears to be a general strategy for designing technically applicable CQD-syntheses. The ``size control by rate control'' concept allows full-yield syntheses of ensembles of CQDs with different sizes by tuning the solute formation rate. In this work, we extended this strategy to dialkylphosphine enhanced hot-injection synthesis of PbSe-CQDs. Furthermore, we provide new insight into the reaction mechanism of dialkylphosphine enhancement in TOPSe based CQD-syntheses. Electronic supplementary information (ESI) available: Additional data about the reaction and growth kinetics, NMR-data and exemplary TEM images of PbSe-CQDs prepared by the procedure described in this publication. See DOI: 10.1039/c5nr00028a

  15. Effect of particle size on microstructure and mechanical properties of composites produced by ARB process

    Energy Technology Data Exchange (ETDEWEB)

    Jamaati, Roohollah, E-mail: r.jamaatikenari@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Amirkhanlou, Sajjad; Toroghinejad, Mohammad Reza; Niroumand, Behzad [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-02-25

    Research highlights: {yields} Microstructure of MMC with larger particles becomes completely uniform, sooner. {yields} When the number of cycles increased, tensile strength for both samples improved. {yields} Up to the seventh cycle, tensile strength of MMC with larger particles was bigger. {yields} First, the tensile elongation of MMCs was decreased, and then it was improved. - Abstract: In the present work, Al/10 vol.% SiC metal matrix composite (MMC) was manufactured by accumulative roll bonding (ARB) process. The silicon carbide particles with two various particle sizes of 40 and 2 {mu}m were used. Effect of particle size on microstructure (by scanning electron microscopy) and mechanical properties (tensile strength and elongation) at various ARB cycles was investigated. It was found that the microstructural evolution in MMC with 40 {mu}m particle size was more salient compared to the MMCs with 2 {mu}m particle size. Also, the composite strip with 40 {mu}m particle size became uniform with high bonding quality and without any porosity sooner than the strip of 2 {mu}m particle size. Moreover, when the number of cycles was increased, the tensile strength for both samples was improved. The tensile strength of the composite strip with 40 {mu}m particle size was more than the composite strip with 2 {mu}m up to the seventh cycle. By increasing the number of cycles after the seventh cycle, the value of tensile strength of MMC with 40 {mu}m particle size became saturated and then decreased, and its tensile strength became less than that of the composite with 2 {mu}m particle size for the ninth and eleventh cycles. Up to the seventh cycle, when the number of ARB cycles was increased, the elongation of composite strips was decreased, but after the ninth cycle, the tensile elongation for both samples was improved.

  16. Tunability of Size and Magnetic Moment of Iron Oxide Nanoparticles Synthesized by Forced Hydrolysis

    Directory of Open Access Journals (Sweden)

    Ben Sutens

    2016-07-01

    Full Text Available To utilize iron oxide nanoparticles in biomedical applications, a sufficient magnetic moment is crucial. Since this magnetic moment is directly proportional to the size of the superparamagnetic nanoparticles, synthesis methods of superparamagnetic iron oxide nanoparticles with tunable size are desirable. However, most existing protocols are plagued by several drawbacks. Presented here is a one-pot synthesis method resulting in monodisperse superparamagnetic iron oxide nanoparticles with a controllable size and magnetic moment using cost-effective reagents. The obtained nanoparticles were thoroughly characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD and Fourier transform infrared (FT-IR measurements. Furthermore, the influence of the size on the magnetic moment of the nanoparticles is analyzed by superconducting quantum interference device (SQUID magnetometry. To emphasize the potential use in biomedical applications, magnetic heating experiments were performed.

  17. Comparison of particle size of cracking catalyst determined by laser light scattering and dry sieve methods

    Energy Technology Data Exchange (ETDEWEB)

    Dishman, K.L.; Doolin, P.K.; Hoffman, J.F. (Ashland Petroleum Co., Ashland, KY (United States))

    1993-07-01

    A method of interconversion of dry sieve and laser light scattering particle size values has been developed for cracking catalysts. Values obtained by light scattering techniques were consistently larger than those obtained by dry sieve analysis. The differences were primarily due to lack of sphericity of the particles. The particle size distribution determined by light scattering techniques was based on an average particle diameter. Conversely, the sieve measured the smallest diameter of the particle which can pass through the opening. Microscopic examination of commercial cracking catalysts confirmed their nonuniformity. The sphericity of the catalyst particles decreased as particle size increased. Therefore, the divergence between the laser light scattering and dry sieving value became greater as the catalyst particle size increased.

  18. Determination of Size Distributions in Nanocrystalline Powders by TEM, XRD and SAXS

    DEFF Research Database (Denmark)

    Jensen, Henrik; Pedersen, Jørgen Houe; Jørgensen, Jens Erik

    2006-01-01

    available powders showed different morphologies. The SSEC78 powder showed the narrowest sizes distribution while UV100 and TiO2_5nm consisted of the smallest primary particles. SSEC78, UV100, and TiO2_5nm consisted of both primary particles as well as a secondary structure comprised of nanosized primary......Crystallite size distributions and particle size distributions were determined by TEM, XRD, and SAXS for three commercially available TiO2 samples and one homemade. The theoretical Guinier Model was fitted to the experimental data and compared to analytical expressions. Modeling of the XRD spectra...

  19. Indication of the radiofrequency induced lesion size by pre-ablation measurements

    DEFF Research Database (Denmark)

    Stagegaard, Niels; Petersen, Helen Høgh; Chen, Xu;

    2005-01-01

    for assessing these factors prior to ablation may indicate the lesion size which will be obtained for any given catheter position. METHODS AND RESULTS: Radiofrequency ablation was performed in vitro on strips of left ventricular porcine myocardium during two different levels of convective cooling (0 or 0.1 m......, during unchanged conditions, radiofrequency ablation was performed as either temperature-controlled, power-controlled or irrigated tip ablation and lesion size was determined. DeltaIMP increased significantly (P convective cooling. Delta......T was significantly increased by increasing contact pressure (P correlation between the obtained lesion size and power output...

  20. Size measuring techniques as tool to monitor pea proteins intramolecular crosslinking by transglutaminase treatment.

    Science.gov (United States)

    Djoullah, Attaf; Krechiche, Ghali; Husson, Florence; Saurel, Rémi

    2016-01-01

    In this work, techniques for monitoring the intramolecular transglutaminase cross-links of pea proteins, based on protein size determination, were developed. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles of transglutaminase-treated low concentration (0.01% w/w) pea albumin samples, compared to the untreated one (control), showed a higher electrophoretic migration of the major albumin fraction band (26 kDa), reflecting a decrease in protein size. This protein size decrease was confirmed, after DEAE column purification, by dynamic light scattering (DLS) where the hydrodynamic radius of treated samples appears to be reduced compared to the control one.

  1. Particle size tailoring of ursolic acid nanosuspensions for improved anticancer activity by controlled antisolvent precipitation.

    Science.gov (United States)

    Wang, Yancai; Song, Ju; Chow, Shing Fung; Chow, Albert H L; Zheng, Ying

    2015-10-15

    The present study was aimed at tailoring the particle size of ursolic acid (UA) nanosuspension for improved anticancer activity. UA nanosuspensions were prepared by antisolvent precipitation using a four-stream multi-inlet vortex mixer (MIVM) under defined conditions of varying solvent composition, drug feeding concentration or stream flow rate. The resulting products were characterized for particle size and polydispersity. Two of the UA nanosuspensions with mean particle sizes of 100 and 300 nm were further assessed for their in-vitro activity against MCF-7 breast cancer cells using fluorescence microscopy with 4',6-diamidino-2-phenylindole (DAPI) staining, as well as flow cytometry with propidium (PI) staining and with double staining by fluorescein isothiocyanate. It was revealed that the solvent composition, drug feeding concentration and stream flow rate were critical parameters for particle size control of the UA nanosuspensions generated with the MIVM. Specifically, decreasing the UA feeding concentration or increasing the stream flow rate or ethanol content resulted in a reduction of particle size. Excellent reproducibility for nanosuspension production was demonstrated for the 100 and 300 nm UA preparations with a deviation of not more than 5% in particle size from the mean value of three independent batches. Fluorescence microscopy and flow cytometry revealed that these two different sized UA nanosuspensions, particularly the 300 nm sample, exhibited a higher anti-proliferation activity against the MCF-7 cells and afforded a larger population of these cells in both early and late apoptotic phases. In conclusion, MIVM is a robust and pragmatic tool for tailoring the particle size of the UA nanosuspension. Particle size appears to be a critical determinant of the anticancer activity of the UA nanoparticles.

  2. Manifestation of unusual size effects in granular thin films prepared by pulsed laser deposition

    Science.gov (United States)

    Sergeenkov, S.; Cichetto, L.; Diaz, J. C. C. A.; Bastos, W. B.; Longo, E.; Araújo-Moreira, F. M.

    2016-11-01

    We demonstrate manifestation of some rather unusual size effects in granular thin films prepared by a pulsed laser deposition technique. We observed that the temperature dependence of resistivity ρ(T) notably depends on the relation between the grain size Rg and the film thickness d. Namely, more granular LaNiO3 thin films (with small values of Rg) grown on LaAlO3 substrate are found to follow a universal ρ(T) ∝T 3 / 2 law for all the measured temperatures. While less granular thin films (with larger values of Rg), exhibit a more complicated behavior accompanied by a clear-cut crossover (around Tcr = 200 K), from ρ(T) ∝T 3 / 2 (for 20 K temperature size effects (when an average grain size Rg becomes comparable with the thermal de Broglie wavelength Λ) leading to the crossover temperature Tcr ∝(d /Rg) 2 .

  3. SCF(SAP) controls organ size by targeting PPD proteins for degradation in Arabidopsis thaliana.

    Science.gov (United States)

    Wang, Zhibiao; Li, Na; Jiang, Shan; Gonzalez, Nathalie; Huang, Xiahe; Wang, Yingchun; Inzé, Dirk; Li, Yunhai

    2016-04-06

    Control of organ size by cell proliferation and growth is a fundamental process, but the mechanisms that determine the final size of organs are largely elusive in plants. We have previously revealed that the ubiquitin receptor DA1 regulates organ size by repressing cell proliferation in Arabidopsis. Here we report that a mutant allele of STERILE APETALA (SAP) suppresses the da1-1 mutant phenotype. We show that SAP is an F-box protein that forms part of a SKP1/Cullin/F-box E3 ubiquitin ligase complex and controls organ size by promoting the proliferation of meristemoid cells. Genetic analyses suggest that SAP may act in the same pathway with PEAPOD1 and PEAPOD2, which are negative regulators of meristemoid proliferation, to control organ size, but does so independently of DA1. Further results reveal that SAP physically associates with PEAPOD1 and PEAPOD2, and targets them for degradation. These findings define a molecular mechanism by which SAP and PEAPOD control organ size.

  4. Droplet size prediction in the production of drug delivery microsystems by ultrasonic atomization.

    Science.gov (United States)

    Dalmoro, Annalisa; d'Amore, Matteo; Barba, Anna Angela

    2013-01-01

    Microencapsulation processes of drugs or other functional molecules are of great interest in pharmaceutical production fields. Ultrasonic assisted atomization is a new technique to produce microencapsulated systems by mechanical approach. It seems to offer several advantages (low level of mechanical stress in materials, reduced energy request, reduced apparatuses size) with respect to more conventional techniques. In this paper the groundwork of atomization is briefly introduced and correlations to predict droplet size starting from process parameters and material properties are presented.

  5. Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

    Science.gov (United States)

    Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

    2013-02-01

    In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized by dynamic light scattering (DLS) and the stability evaluated by analytical centrifugation (LUMiFuge). The selected dispersions were tested for film formation ability by scanning electron microscopy (SEM), and the sizing performance was assessed by observation of the fiber/matrix interface by SEM. The results revealed that an aqueous dispersion of PEI, stabilized by sodium dodecyl sulfate as the surfactant, led to very stable sizing agent aqueous dispersion with ideal film formation and better interface adhesion.

  6. Control of root meristem size by DA1-RELATED PROTEIN2 in Arabidopsis.

    Science.gov (United States)

    Peng, Yuancheng; Ma, Wenying; Chen, Liangliang; Yang, Lei; Li, Shengjun; Zhao, Hongtao; Zhao, Yankun; Jin, Weihuan; Li, Na; Bevan, Michael W; Li, Xia; Tong, Yiping; Li, Yunhai

    2013-03-01

    The control of organ growth by coordinating cell proliferation and differentiation is a fundamental developmental process. In plants, postembryonic root growth is sustained by the root meristem. For maintenance of root meristem size, the rate of cell differentiation must equal the rate of cell division. Cytokinin and auxin interact to affect the cell proliferation and differentiation balance and thus control root meristem size. However, the genetic and molecular mechanisms that determine root meristem size still remain largely unknown. Here, we report that da1-related protein2 (dar2) mutants produce small root meristems due to decreased cell division and early cell differentiation in the root meristem of Arabidopsis (Arabidopsis thaliana). dar2 mutants also exhibit reduced stem cell niche activity in the root meristem. DAR2 encodes a Lin-11, Isl-1, and Mec-3 domain-containing protein and shows an expression peak in the border between the transition zone and the elongation zone. Genetic analyses show that DAR2 functions downstream of cytokinin and SHORT HYPOCOTYL2 to maintain normal auxin distribution by influencing auxin transport. Further results indicate that DAR2 acts through the PLETHORA pathway to influence root stem cell niche activity and therefore control root meristem size. Collectively, our findings identify the role of DAR2 in root meristem size control and provide a novel link between several key regulators influencing root meristem size.

  7. Constant size, variable density aerosol particles by ultrasonic spray freeze drying.

    Science.gov (United States)

    D'Addio, Suzanne M; Chan, John Gar Yan; Kwok, Philip Chi Lip; Prud'homme, Robert K; Chan, Hak-Kim

    2012-05-10

    This work provides a new understanding of critical process parameters involved in the production of inhalation aerosol particles by ultrasonic spray freeze drying to enable precise control over particle size and aerodynamic properties. A series of highly porous mannitol, lysozyme, and bovine serum albumin (BSA) particles were produced, varying only the solute concentration in the liquid feed, c(s), from 1 to 5 wt%. The particle sizes of mannitol, BSA, and lysozyme powders were independent of solute concentration, and depend only on the drop size produced by atomization. Both mannitol and lysozyme formulations showed a linear relationship between the computed Fine Particle Fraction (FPF) and the square root of c(s), which is proportional to the particle density, ρ, given a constant particle size d(g). The FPF decreased with increasing c(s) from 57.0% to 16.6% for mannitol and 44.5% to 17.2% for lysozyme. Due to cohesion, the BSA powder FPF measured by cascade impaction was less than 10% and independent of c(s). Ultrasonic spray freeze drying enables separate control over particle size, d(g), and aerodynamic size, d(a) which has allowed us to make the first experimental demonstration of the widely accepted rule d(a)=d(g)(ρ/ρ(o))(1/2) with particles of constant d(g), but variable density, ρ (ρ(o) is unit density).

  8. Size dependence of surface thermodynamic properties of nanoparticles and its determination method by reaction rate constant

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenjiao; Xue, Yongqiang, E-mail: xyqlw@126.com; Cui, Zixiang

    2016-08-15

    Surface thermodynamic properties are the fundamental properties of nanomaterials, and these properties depend on the size of nanoparticles. In this paper, relations of molar surface thermodynamic properties and surface heat capacity at constant pressure of nanoparticles with particle size were derived theoretically, and the method of obtaining the surface thermodynamic properties by reaction rate constant was put forward. The reaction of nano-MgO with sodium bisulfate solution was taken as a research system. The influence regularities of the particle size on the surface thermodynamic properties were discussed theoretically and experimentally, which show that the experimental regularities are in accordance with the corresponding theoretical relations. With the decreasing of nanoparticle size, the molar surface thermodynamic properties increase, while the surface heat capacity decreases (the absolute value increases). In addition, the surface thermodynamic properties are linearly related to the reciprocal of nanoparticle diameter, respectively.

  9. Control over particle size distribution by autoclaving poloxamer-stabilized trimyristin nanodispersions

    DEFF Research Database (Denmark)

    Göke, Katrin; Roese, Elin; Arnold, Andreas

    2016-01-01

    into the bloodstream. Consequently, small particles with a narrow particle size distribution are desired. Hitherto, there are, however, only limited possibilities for the preparation of monodisperse, pharmaceutically relevant dispersions. In this work, the effect of autoclaving at 121 °C on the particle size...... distribution of lipid nanoemulsions and -suspensions consisting of the pharmaceutically relevant components trimyristin and poloxamer 188 was studied. Additionally, the amount of emulsifier needed to stabilize both untreated and autoclaved particles was assessed. In our study, four dispersions of mean particle...... sizes from 45 to 150 nm were prepared by high-pressure melt homogenization. The particle size distribution before and after autoclaving was characterized using static and dynamic light scattering, differential scanning calorimetry, and transmission electron microscopy. Asymmetrical flow field...

  10. Determination of myocardial infarction size in rats by echocardiography and tetrazolium staining: correlation, agreements, and simplifications.

    Science.gov (United States)

    dos Santos, L; Mello, A F S; Antonio, E L; Tucci, P J F

    2008-03-01

    Triphenyltetrazolium chloride (TTC) staining and echocardiography (ECHO) are methods used to determine experimental myocardial infarction (MI) size, whose practical applicability should be expanded. Our objectives were to analyze the accuracy of ECHO in determining infarction size in rats during the first days following coronary occlusion and to test whether a simplified single measurement by TTC correctly indicates MI size, as determined by the average value for multiple slices. Infarction was induced in female Wistar rats by coronary artery occlusion and MI size analysis was performed after the acute (7th day) and chronic periods (after 4 weeks) by ECHO matched with TTC. ECHO and TTC showed similar values of MI size (% of left ventricle perimeter) in acute (ECHO: 33 +/- 11, TTC: 35 +/- 14) and chronic (ECHO: 38 +/- 14, TTC: 39 +/- 13 periods), and also presented an excellent correlation (r = 0.92, P < 0.001). Although measurements from different heart planes showed discrepancies, a single measurement acquired from the mid-ventricular level by TTC was a good estimate of MI size calculated by the average of multiple planes, with minimal disagreement (Bland-Altman test with mean ratio bias of 0.99 +/- 0.07) and close to an ideal correlation (r = 0.99, P < 0.001). In the present study, ECHO was confirmed as a useful method for the determination of MI size even in the acute phase. Also, the single measure of a mid-ventricular section proposed as a simplification of the TTC method is a satisfactory prediction of average MI extension.

  11. Investment in higher order central processing regions is not constrained by brain size in social insects.

    Science.gov (United States)

    Muscedere, Mario L; Gronenberg, Wulfila; Moreau, Corrie S; Traniello, James F A

    2014-06-07

    The extent to which size constrains the evolution of brain organization and the genesis of complex behaviour is a central, unanswered question in evolutionary neuroscience. Advanced cognition has long been linked to the expansion of specific brain compartments, such as the neocortex in vertebrates and the mushroom bodies in insects. Scaling constraints that limit the size of these brain regions in small animals may therefore be particularly significant to behavioural evolution. Recent findings from studies of paper wasps suggest miniaturization constrains the size of central sensory processing brain centres (mushroom body calyces) in favour of peripheral, sensory input centres (antennal and optic lobes). We tested the generality of this hypothesis in diverse eusocial hymenopteran species (ants, bees and wasps) exhibiting striking variation in body size and thus brain size. Combining multiple neuroanatomical datasets from these three taxa, we found no universal size constraint on brain organization within or among species. In fact, small-bodied ants with miniscule brains had mushroom body calyces proportionally as large as or larger than those of wasps and bees with brains orders of magnitude larger. Our comparative analyses suggest that brain organization in ants is shaped more by natural selection imposed by visual demands than intrinsic design limitations.

  12. Genetics of recent habitat contraction and reduction in population size: does isolation by distance matter?

    Science.gov (United States)

    Leblois, Raphael; Estoup, Arnaud; Streiff, Rejane

    2006-10-01

    Fragmentation and loss of natural habitats are recognized as major threats to contemporary flora and fauna. Detecting past or current reductions in population size is therefore a major aim in conservation genetics. Statistical methods developed to this purpose have tended to ignore the effects of spatial population structure. However in many species, individual dispersal is restricted in space and fine-scale spatial structure such as isolation by distance (IBD) is commonly observed in continuous populations. Using a simulation-based approach, we investigated how comparative and single-point methods, traditionally used in a Wright-Fisher (WF) population context for detecting population size reduction, behave for IBD populations. We found that a complex 'quartet' of factors was acting that includes restricted dispersal, population size (i.e. habitat size), demographic history, and sampling scale. After habitat reduction, IBD populations were characterized by a stronger inertia in the loss of genetic diversity than WF populations. This inertia increases with the strength of IBD, and decreases when the sampling scale increases. Depending on the method used to detect a population size reduction, a local sampling can be more informative than a sample scaled to habitat size or vice versa. However, IBD structure led in numerous cases to incorrect inferences on population demographic history. The reanalysis of a real microsatellite data set of skink populations from fragmented and intact rainforest habitats confirmed most of our simulation results.

  13. Organelle Size Scaling of the Budding Yeast Vacuole by Relative Growth and Inheritance.

    Science.gov (United States)

    Chan, Yee-Hung M; Reyes, Lorena; Sohail, Saba M; Tran, Nancy K; Marshall, Wallace F

    2016-05-09

    It has long been noted that larger animals have larger organs compared to smaller animals of the same species, a phenomenon termed scaling [1]. Julian Huxley proposed an appealingly simple model of "relative growth"-in which an organ and the whole body grow with their own intrinsic rates [2]-that was invoked to explain scaling in organs from fiddler crab claws to human brains. Because organ size is regulated by complex, unpredictable pathways [3], it remains unclear whether scaling requires feedback mechanisms to regulate organ growth in response to organ or body size. The molecular pathways governing organelle biogenesis are simpler than organogenesis, and therefore organelle size scaling in the cell provides a more tractable case for testing Huxley's model. We ask the question: is it possible for organelle size scaling to arise if organelle growth is independent of organelle or cell size? Using the yeast vacuole as a model, we tested whether mutants defective in vacuole inheritance, vac8Δ and vac17Δ, tune vacuole biogenesis in response to perturbations in vacuole size. In vac8Δ/vac17Δ, vacuole scaling increases with the replicative age of the cell. Furthermore, vac8Δ/vac17Δ cells continued generating vacuole at roughly constant rates even when they had significantly larger vacuoles compared to wild-type. With support from computational modeling, these results suggest there is no feedback between vacuole biogenesis rates and vacuole or cell size. Rather, size scaling is determined by the relative growth rates of the vacuole and the cell, thus representing a cellular version of Huxley's model.

  14. Size effect of Raman scattering on CeO2 nanocrystal by hydrothermal method

    Science.gov (United States)

    Hattori, Takashi; Kobayashi, Katsutoshi; Ozawa, Masakuni

    2017-01-01

    In this study, we prepared surface-modified CeO2 nanocrystals (NCs) by a hydrothermal method, and calcined CeO2 NCs at various temperatures between 400 and 1000 °C for 3 h in air to obtain crystal-size-controlled CeO2 NCs. We investigated the correlation between the Raman spectra and the crystal sizes of the CeO2 powder. The peak position of the F2g mode of CeO2 was shifted to lower energies as the crystal size decreased and the peak broadened. The present hydrothermally driven CeO2 NCs showed no change in lattice constant depending on crystal size after heat treatment. The Raman peak position of the F2g mode as a function of inverse CeO2 crystal size corresponded to the models for phonon confinement without the combination of strain and defect effects. Moreover, it was also suggested that the Raman peak width of CeO2 NCs without strain also showed dependence on particle size.

  15. Impact of temperature on zinc oxide particle size by using sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Keanchuan, E-mail: lee.kc@petronas.com.my; Ching, Dennis Ling Chuan, E-mail: dennis.ling@petronas.com.my [Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia); Saipolbahri, Zulhilmi Akmal bin, E-mail: zulhilmiakmal@gmail.com [Geoscience and Petroleum Engineering Department, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak (Malaysia); Guan, Beh Hoe, E-mail: beh.hoeguan@petronas.com.my, E-mail: hassan.soleimani@petronas.com.my; Soleimani, Hassan, E-mail: beh.hoeguan@petronas.com.my, E-mail: hassan.soleimani@petronas.com.my

    2014-10-24

    Zinc oxide (ZnO) nanoparticles were prepared and synthesized via sol-gel method, by using citric acid as a precursor. The impact of annealing on the particle size was investigated. Based on the results from the Thermogravimetric Analysis (TGA), three different annealing temperature which is 500, 600 and 700 °C were chosen followed by the characterization of the ZnO nanoparticle by using Powder X-Ray Diffraction (PXRD), Transmission Electron Microscopy (TEM) and Field Emission Scanning Electron Microscopy (FESEM). Results showed that the crystallite size estimated from PXRD increased with the annealing temperature which was hexagonal structure for ZnO. TEM further revealed the same tendency which the Zn NPs size also increased with the annealing temperature.

  16. Determining proportions of lunar crater populations by fitting crater size distribution

    CERN Document Server

    Wang, Nan

    2016-01-01

    We determine the proportions of two mixed crater populations distinguishable by size distributions on the Moon. A "multiple power-law" model is built to formulate crater size distribution $N(D) \\propto D^{-\\alpha}$ whose slope $\\alpha$ varies with crater diameter $D$. Fitted size distribution of lunar highland craters characterized by $\\alpha = 1.17 \\pm 0.04$, $1.88 \\pm 0.07$, $3.17 \\pm 0.10$ and $1.40 \\pm 0.15$ for consecutive $D$ intervals divided by 49, 120 and 251 km and that of lunar Class 1 craters with a single slope $\\alpha = 1.96 \\pm 0.14$, are taken as Population 1 and 2 crater size distribution respectively, whose sum is then fitted to the size distribution of global lunar craters with $D$ between 10 and 100 km. Estimated crater densities of Population 1 and 2 are $44 \\times 10^{-5}$ and $5 \\times 10^{-5}$ km$^{-2}$ respectively, leading to the proportion of the latter $10 \\%$. The results underlines the need for considering the Population 1 craters and the relevant impactors, the primordial main-b...

  17. Regulation of Caenorhabditis elegans body size and male tail development by the novel gene lon-8

    Directory of Open Access Journals (Sweden)

    Korswagen Hendrik C

    2007-03-01

    Full Text Available Abstract Background In C. elegans and other nematode species, body size is determined by the composition of the extracellular cuticle as well as by the nuclear DNA content of the underlying hypodermis. Mutants that are defective in these processes can exhibit either a short or a long body size phenotype. Several mutations that give a long body size (Lon phenotype have been characterized and found to be regulated by the DBL-1/TGF-β pathway, that controls post-embryonic growth and male tail development. Results Here we characterize a novel gene affecting body size. lon-8 encodes a secreted product of the hypodermis that is highly conserved in Rhabditid nematodes. lon-8 regulates larval elongation as well as male tail development. In both processes, lon-8 appears to function independently of the Sma/Mab pathway. Rather, lon-8 genetically interacts with dpy-11 and dpy-18, which encode cuticle collagen modifying enzymes. Conclusion The novel gene lon-8 encodes a secreted product of the hypodermis that controls body size and male ray morphology in C. elegans. lon-8 genetically interacts with enzymes that affect the composition of the cuticle.

  18. Simultaneous measurement of droplet size and velocity field by an interferometric imaging technique in spray combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fujisawa, N.; Hosokawa, A.; Tomimatsu, S. [Niigata Univ. (Japan). Dept. of Mechanical and Production Engineering

    2003-08-01

    The present paper describes an experimental technique of droplet sizing and velocity measurement for application to a luminous flame in spray combustion. The size measurement of unburnt fuel droplets in combustion is carried out by using an interferometric imaging method, while the corresponding velocity field is measured by particle tracking velocimetry (PTV) in combination with the rotary shutter to avoid the high intensity noise of the luminous flame in spray combustion. The measurements are successfully applied to the spray flow from a gun-type burner with and without combustion. The experimental results in spray combustion indicate that the smaller size of fuel droplets are almost burnt in the centre of the flame and the unburnt droplets of larger size remain in the outer region of the burner flow. It was found that the mean droplet velocity measured by the present PTV technique in combustion is almost independent of the droplet size and agrees closely with the gas velocity. However, the velocity magnitude with combustion is increased in comparison with the case without combustion, which suggests the influence of gas expansion at high temperatures. (author)

  19. Pore Size Distribution in Chicken Eggs as Determined by Mercury Porosimetry

    Directory of Open Access Journals (Sweden)

    La Scala Jr N

    2000-01-01

    Full Text Available In this study we investigated the application of mercury porosimetry technique into the determination of porosity features in 28 week old hen eggshells. Our results have shown that the majority of the pores have sizes between 1 to 10 mu m in the eggshells studied. By applying mercury porosimetry technique we were able to describe the porosity features better, by determining a pore size distribution in the eggshells. Here, we introduce mercury porosimetry technique as a new routine technique applied into the study of eggshells.

  20. Control of sizes and densities of nano catalysts for nanotube synthesis by plasma breaking method

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J.S.; Umeda, K.; Uchino, K.; Nakashima, H.; Muraoka, K

    2004-03-15

    Sizes and densities of nano catalysts for carbon nanotube synthesis, formed by the plasma breaking method of thin Fe films deposited using pulse laser deposition (PLD) were controlled by the changes of operating parameters. At the best optimum condition, nano catalysts with a density of 1.9x10{sup 15} m{sup -2} and a diameter of about 15 nm were obtained. Carbon nanotubes (CNTs) synthesized on these catalysts were shown to have almost the same size and density as those of the catalysts.

  1. Profit based phase II sample size determination when adaptation by design is adopted

    OpenAIRE

    Martini, D.

    2014-01-01

    Background. Adaptation by design consists in conservatively estimating the phase III sample size on the basis of phase II data, and can be applied in almost all therapeutic areas; it is based on the assumption that the effect size of the drug is the same in phase II and phase III trials, that is a very common scenario assumed in product development. Adaptation by design reduces the probability on underpowered experiments and can improve the overall success probability of phase II and III tria...

  2. Preparation of Small Particle Sized ZnAl-Hydrotalcite-Like Compounds by Ultrasonic Crystallization

    Institute of Scientific and Technical Information of China (English)

    Xianmei Xie; Xiurong Ren; Jinping Li; Xiaojun Hu; Zhizhong Wang

    2006-01-01

    Ultrasonic technology has been intensively studied recently due to its special features. In this paper, an ultrasonic crystallization method was introduced for the preparation of ZnAl-Hydrotalcite-Like compounds (ZnAl-HTLcs). Samples with high crystallinity, small particle size and narrow particle size distribution were obtained and fully characterized using conventional techniques of XRD, FT-IR and TG-DTA. The results prove that both ultrasonic frequency and ultrasonic power have effects on the sizes of the product particles. By varying the ultrasonic power from 250 W to 88 W, with the ultrasonic frequency fixed at 59 kHz, the median particle size of the samples increased from 0.37μm to 0.82μm. By altering the hydrothermal treatment time from 1 h to 5 h at 110 ℃, the median particle size of ZnAl-HTLcs synthesized via ultrasonic crystallization increased from 0.88 μm to 1.11 μm.

  3. Particle size- and number-dependent delivery to cells by layered double hydroxide nanoparticles.

    Science.gov (United States)

    Dong, Haiyan; Parekh, Harendra S; Xu, Zhi Ping

    2015-01-01

    It is well known that delivery efficiency to cells is highly dependent on particle size and the administered dose. However, there is a marked discrepancy in many reports, mainly due to the inconsistency in assessment of various parameters. In this particular research, we designed experiments using layered double hydroxide nanoparticles (LDH NPs) to specifically elucidate the effect of particle size, dose and dye loading manner on cellular uptake. Using the number of LDH NPs taken up by HCT-116 cells as the indicator of delivery efficiency, we found that (1) the size of sheet-like LDH in the range of 40-100 nm did not significantly affect their cellular uptake; (2) cellular uptake of 40 and 100 nm LDH NPs was increased proportionally to the number concentration below a critical value, but remained relatively constant beyond the critical value; and (3) the effect of the dye loading manner is mainly dependent on the loading capacity or yield. In particular, the loading capacity is determined by the NP specific surface area. This research may be extended to a larger size range to examine the size effect, but suggests that it is necessary to set up a protocol to evaluate the effects of NP's physicochemical properties on the cellular delivery efficiency.

  4. Effects of surfactants on size and structure of amylose nanoparticles prepared by precipitation

    Indian Academy of Sciences (India)

    Yan Dong; Yanjiao Chang; Qian Wang; Jin Tong; Jiang Zhou

    2016-02-01

    The present work investigated the influence of surfactants on size and structure of amylose nanoparticles (ANPs) prepared through precipitation. ANPs were fabricated using absolute ethanol containing surfactants (Tween80, Span80 and mixtures of Tween80 and Span80 with ratios of 25/75, 50/50 and 75/25, respectively) as non-solvents. The obtained ANPs were characterized using dynamic light scattering (DLS), scanning electron microscopy and X-ray diffraction. The results showed that surfactant type, concentration and hydrophilic–lipophilic balance (HLB) value had great impact on size of precipitated ANPs. The smallest ANPs with mean size of 155 nm determined by DLS were obtained by using 0.5% (in proportion of the amylose solution volume) of Tween80/Span80 mixture (HLB = 12.33). The precipitated ANPs possessed the V-type crystalline structure no matter whether using the surfactants or not.

  5. Numerical Simulation of Sub-cooled Cavitating Flow by Using Bubble Size Distribution

    Institute of Scientific and Technical Information of China (English)

    Yutaka ITO; Hideki WAKAMATSU; Takao NAGASAKI

    2003-01-01

    A new cavitating model by using bubble size distribution based on mass of bubbles is proposed. Liquid phase is treated with Eulerian framework as a mixture containing minute cavitating bubbles. Vapor phase consists of various sizes of minute vapor bubbles, which is distributed to classes based on their mass. The change of bubble number density for each class was solved by considering the change of bubble mass due to phase change as well as generation of new bubbles due to heterogeneous nucleation. In this method the mass of bubbles is treated as an independent variable, in other word, a new coordinate, and dependant variables are solved in Eulerian framework for spatial coordinates and bubble-mass coordinate. The present method is applied to a cavitating flow in a convergent-divergent nozzle, and the two-phase flow with bubble size distribution and phase change was successfully predicted.

  6. The Cambrian explosion triggered by critical turning point in genome size evolution.

    Science.gov (United States)

    Li, Dirson Jian; Zhang, Shengli

    2010-02-05

    The Cambrian explosion is a grand challenge to science today and involves multidisciplinary study. This event is generally believed as a result of genetic innovations, environmental factors and ecological interactions, even though there are many conflicts on nature and timing of metazoan origins. The crux of the matter is that an entire roadmap of the evolution is missing to discern the biological complexity transition and to evaluate the critical role of the Cambrian explosion in the overall evolutionary context. Here, we calculate the time of the Cambrian explosion by a "C-value clock"; our result quite fits the fossil records. We clarify that the intrinsic reason of genome evolution determined the Cambrian explosion. A general formula for evaluating genome size of different species has been found, by which the genome size evolution can be illustrated. The Cambrian explosion, as a major transition of biological complexity, essentially corresponds to a critical turning point in genome size evolution.

  7. Modeling group size and scalar stress by logistic regression from an archaeological perspective.

    Directory of Open Access Journals (Sweden)

    Gianmarco Alberti

    Full Text Available Johnson's scalar stress theory, describing the mechanics of (and the remedies to the increase in in-group conflictuality that parallels the increase in groups' size, provides scholars with a useful theoretical framework for the understanding of different aspects of the material culture of past communities (i.e., social organization, communal food consumption, ceramic style, architecture and settlement layout. Due to its relevance in archaeology and anthropology, the article aims at proposing a predictive model of critical level of scalar stress on the basis of community size. Drawing upon Johnson's theory and on Dunbar's findings on the cognitive constrains to human group size, a model is built by means of Logistic Regression on the basis of the data on colony fissioning among the Hutterites of North America. On the grounds of the theoretical framework sketched in the first part of the article, the absence or presence of colony fissioning is considered expression of not critical vs. critical level of scalar stress for the sake of the model building. The model, which is also tested against a sample of archaeological and ethnographic cases: a confirms the existence of a significant relationship between critical scalar stress and group size, setting the issue on firmer statistical grounds; b allows calculating the intercept and slope of the logistic regression model, which can be used in any time to estimate the probability that a community experienced a critical level of scalar stress; c allows locating a critical scalar stress threshold at community size 127 (95% CI: 122-132, while the maximum probability of critical scale stress is predicted at size 158 (95% CI: 147-170. The model ultimately provides grounds to assess, for the sake of any further archaeological/anthropological interpretation, the probability that a group reached a hot spot of size development critical for its internal cohesion.

  8. Effect of population size on genetic variation levels in Capparis spinosa (Capparaceae detected by RAPDs

    Directory of Open Access Journals (Sweden)

    Houshang Nosrati

    2012-07-01

    Full Text Available Background: The population size of plants affects on population genetic variation. Materials and Methods: We studied the impact of population size on genetic variation in populations of Capparis spinosa (caper, Capparaceae using RAPDs in East Azerbaijan (Iran. Within-population genetic diversity was estimated based on Nei`s and Shanonn`s diversity using Popgen, and genetic similarity among the populations was studied from a UPGMA dendrogram based the matrix of Nei’s distances obtained through SHAN. Difference in the level genetic variation between small-sized and large-sized populations was tested using Mann-Whitney U test, and correlation between geographical and genetic distances among populations was examined by Pearson test (SPSS, 11.3. Total genetic variation was partitioned into within and among populations based on AMOVA using Arlequin. Results: The polymorphism levels of RAPDs bands among the populations ranged from 48.8% to 81.4%, and within-population Nei’s diversity varied from 0.1667 to 0.2630. Genetic variation in small-sized populations (0.1667 to 0.1809 was significantly lower than the variations in large-sized populations (0.2158 -0.2630 (N= 7, P0.674, Pearson correlation test. Conclusions: Population size has a dramatic impact on its genetic diversity. The results revealed that fragmentation of caper population in the study region has most likely occurred recently. The low genetic diversity revealed within caper populations indicates high risk of extinction and suggests that urgent conservation action is needed to recover diversity in these populations.

  9. Microfluidic sorting of protein nanocrystals by size for X-ray free-electron laser diffraction

    Directory of Open Access Journals (Sweden)

    Bahige G. Abdallah

    2015-07-01

    Full Text Available The advent and application of the X-ray free-electron laser (XFEL has uncovered the structures of proteins that could not previously be solved using traditional crystallography. While this new technology is powerful, optimization of the process is still needed to improve data quality and analysis efficiency. One area is sample heterogeneity, where variations in crystal size (among other factors lead to the requirement of large data sets (and thus 10–100 mg of protein for determining accurate structure factors. To decrease sample dispersity, we developed a high-throughput microfluidic sorter operating on the principle of dielectrophoresis, whereby polydisperse particles can be transported into various fluid streams for size fractionation. Using this microsorter, we isolated several milliliters of photosystem I nanocrystal fractions ranging from 200 to 600 nm in size as characterized by dynamic light scattering, nanoparticle tracking, and electron microscopy. Sorted nanocrystals were delivered in a liquid jet via the gas dynamic virtual nozzle into the path of the XFEL at the Linac Coherent Light Source. We obtained diffraction to ∼4 Å resolution, indicating that the small crystals were not damaged by the sorting process. We also observed the shape transforms of photosystem I nanocrystals, demonstrating that our device can optimize data collection for the shape transform-based phasing method. Using simulations, we show that narrow crystal size distributions can significantly improve merged data quality in serial crystallography. From this proof-of-concept work, we expect that the automated size-sorting of protein crystals will become an important step for sample production by reducing the amount of protein needed for a high quality final structure and the development of novel phasing methods that exploit inter-Bragg reflection intensities or use variations in beam intensity for radiation damage-induced phasing. This method will also

  10. Synapse clusters are preferentially formed by synapses with large recycling pool sizes.

    Directory of Open Access Journals (Sweden)

    Oliver Welzel

    Full Text Available Synapses are distributed heterogeneously in neural networks. The relationship between the spatial arrangement of synapses and an individual synapse's structural and functional features remains to be elucidated. Here, we examined the influence of the number of adjacent synapses on individual synaptic recycling pool sizes. When measuring the discharge of the styryl dye FM1-43 from electrically stimulated synapses in rat hippocampal tissue cultures, a strong positive correlation between the number of neighbouring synapses and recycling vesicle pool sizes was observed. Accordingly, vesicle-rich synapses were found to preferentially reside next to neighbours with large recycling pool sizes. Although these synapses with large recycling pool sizes were rare, they were densely arranged and thus exhibited a high amount of release per volume. To consolidate these findings, functional terminals were marked by live-cell antibody staining with anti-synaptotagmin-1-cypHer or overexpression of synaptopHluorin. Analysis of synapse distributions in these systems confirmed the results obtained with FM 1-43. Our findings support the idea that clustering of synapses with large recycling pool sizes is a distinct developmental feature of newly formed neural networks and may contribute to functional plasticity.

  11. Pitfalls and novel applications of particle sizing by dynamic light scattering.

    Science.gov (United States)

    Fischer, Karl; Schmidt, Manfred

    2016-08-01

    After briefly introducing the theoretical equations for DLS based particle size analysis, the need for angular dependent DLS investigations is emphasized to obtain correct particle sizes. Practical examples are given that demonstrate the possible magnitudes of errors in particle size if DLS is measured at one large scattering angle, only, as done by essentially all, most frequently utilized commercial "single angle" particle sizers. The second part is focused on a novel DLS application to sensitively trace (nano)particle interactions with concentrated blood serum or plasma that leads to the formation of large aggregates in a size regime of ≫100 nm. Most likely, such aggregates originate from protein induced bridging of nanoparticles, since it is well known that serum proteins adsorb onto the surface of essentially all nanoparticles utilized in medical applications. Thus, the protein corona around nanoparticles does not only change their biological identity but to a large extend also their size, thus possibly affecting biodistribution and in vivo circulation time.

  12. Writing and reading training effects on font type and size preferences by students with low vision.

    Science.gov (United States)

    Atasavun Uysal, Songül; Düger, Tülin

    2012-06-01

    The effect of writing and reading training on preferred font type and size in low-vision students was evaluated in 35 children. An ophthalmologist confirmed low vision according to ICD-10-CM. Children identified the font type and size they could best read. The writing subtest of the Jebsen-Taylor Hand Function Test, read in 1 min., and legibility as measured by the number of readable written letters were used in evaluating the children. A writing and reading treatment program was conducted, beginning with the child's preferred font type and size, for 3 months, 2 days per week, for 45 min. per day at the child's school. Before treatment, the most preferred font type was Verdana; after treatment, the preferred font type and size changed. Students had gained reading and writing speed after training, but their writing legibility was not significantly better. Training might affect the preferred font type and size of students with low vision. Surprisingly, serif and sans-serif fonts were preferred about equally after treatment.

  13. Size Effect of Lattice Thermal Conductivity Across Nanoscale Thin Films by Molecular Dynamics Simulations

    Institute of Scientific and Technical Information of China (English)

    FENG Xiao-Li; LI Zhi-Xin; GUO Zeng-Yuan

    2001-01-01

    Thermal conductivity in the normal direction of ultra-thin dielectric films is predicted by molecular dynamics calculations for argon crystal. For film thicknesses of about 2-10nm within which real measurements cannot yet be implemented, the size dependence of lattice thermal conductivity is captured and a remarkable thermal conductivity drop is found as compared with bulk experimental data. This size effect demonstrates that phonon-boundary scattering in thin films may also be very significant at high temperatures even above the Debye temperature. The influence of different potential models is examined according to the comparison between results from the Lennard-Jones potential and a soft-sphere potential.

  14. Size and functional tuning of solid state nanopores by chemical functionalization

    Science.gov (United States)

    Mussi, Valentina; Fanzio, Paola; Firpo, Giuseppe; Repetto, Luca; Valbusa, Ugo

    2012-11-01

    We demonstrate the possibility of using a simple functionalization procedure, based on an initial vapour-phase silanization, to control the size and functionality of solid state nanopores. The presented results show that, by varying the silanization time, it is possible to modify the efficiency of probe molecule attachment, thus shrinking the pore to the chosen size, while introducing a specific sensing selectivity. The proposed method allows us to tune the nanopore biosensor adapting it to the specific final application, and it can be efficiently applied when the pore initial diameter does not exceed a limit dimension related to the mean free path of the silane molecules at the working pressure.

  15. Size-controlled bismuth nanoparticles physically grown by the support of cobalt atomic flux

    Science.gov (United States)

    Lee, Ho Seok; Noh, Jin-Seo

    2016-04-01

    Bi nanoparticle arrays with the almost monodispersity were synthesized using a magnetically assisted physical method. The average size and the overall morphology of Bi nanoparticles could be controlled by the adjustment of several parameters such as relative powers applied to Bi and Co targets, substrate temperature, and growth time. It was disclosed that Bi nanoparticles grow larger at a higher relative power to Bi, higher substrate temperature, and longer growth time, accompanying the deterioration of well-developed faceted structures. This physical method may provide a facile and fast route to achieving quality Bi nanoparticle arrays with a certain extent of size and morphology controllability.

  16. INSTALLATION FOR LARGE SIZE STAMP HARDENING TRANINIG BY WATER-AIR MIXTURE

    Directory of Open Access Journals (Sweden)

    L. A. Glazkov

    2009-01-01

    Full Text Available The BNTU has developed a technological process for large-size stamp hardening by means of a water-air mixture.  The  basic  requirements  imposed on an hardening  installation using  a  water-air mixture are the following: provision of smooth cooling of a part in order to achieve the required  hardness and structure; possibility of machining parts of various sizes; change of modes for machining parts of various grades of steel according to any hardness rate.The peculiar features of the given installation are: a presence of microprocessor control of water-air mixture supply, possibility of simultaneous machining of a stamp set (2 parts and position change of parts to be hardened in the process of thermal treatment.Installation for large-sized stamp hardening has been manufactured and introduced at theMinskplant of special tools and machining attachments.

  17. Effect of surfactants on the size and shape of cobalt nanoparticles synthesized by thermal decomposition

    Science.gov (United States)

    Shao, Huiping; Huang, Yuqiang; Lee, Hyosook; Suh, Yong Jae; Kim, Chongoh

    2006-04-01

    Cobalt nanoparticles with various morphologies were synthesized by thermal decomposition of cobalt acetate in the presence of various surfactants at 260 °C. A combination of surfactants consisting of sufficient amount of oleic acid together with polyvinylpyrrolidone and oleylamine resulted in well-dispersed cubic cobalt nanoparticles of ~25 nm in average size. When 1,2-dodecanediol was added as a reducing agent to the surfactant mixture, triangular-prism-shaped nanoparticles of ~50 nm in average size were synthesized. Furthermore, an injection of trioctylphosphine into the reactor as an additional surfactant decreased the particle size to ~10 nm. The XRD pattern of the prism-like particles corresponded to hexagonal close-packed crystalline phase of cobalt.

  18. Finding Mars-Sized Planets in Inner Orbits of Other Stars by Photometry

    Science.gov (United States)

    Borucki, W.; Cullers, K.; Dunham, E.; Koch, D.; Mena-Werth, J.; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    High precision photometry from a spaceborne telescope has the potential of discovering sub-earth sized inner planets. Model calculations by Wetherill indicate that Mars-sized planets can be expected to form throughout the range of orbits from that of Mercury to Mars. While a transit of an Earth-sized planet causes a 0.084% decrease in brightness from a solar-like star, a transit of a planet as small as Mars causes a flux decrease of only 0.023%. Stellar variability will be the limiting factor for transit measurements. Recent analysis of solar variability from the SOLSTICE experiment shows that much of the variability is in the UV at planet as small as Mars should be reliably detectable. If Wetherill's models are correct in postulating that Mars-like planets are present in Mercury-like orbits, then a six year search should be able to find them.

  19. Evaluation of the effective thermal conductivity of composite polymers by considering the filler size distribution law

    Institute of Scientific and Technical Information of China (English)

    Sorin HOLOTESCU; Floriana D.STOIAN

    2009-01-01

    We present an empirical model for the effective thermal conductivity(ETC)of a polymer composite that includes dependency on the filler size distribution-chosen as the Rosin-Rammler distribution.The ETC is determined based on certain hypotheses that connect the behavior of a real composite matefial A.to that of a model composite material B,filled with mono-dimensional filler.The application of these hypotheses to the Maxwell model for ETC is presented.The validation of the new model and its characteristic equation was carried out using experimental data from the reference.The comparison showed that by using the size distribution law a very good fit between the equation of the new model(the size distribution model for the ETC)and the reference experimental results is obtained,even for high volume fractions,up to about 50%.

  20. Size-dependent ligand layer dynamics in semiconductor nanocrystals probed by anisotropy measurements.

    Science.gov (United States)

    Hadar, Ido; Abir, Tsafrir; Halivni, Shira; Faust, Adam; Banin, Uri

    2015-10-12

    Colloidal semiconductor nanocrystals (NC) have reached a high level of synthetic control allowing the tuning of their properties, and their use in various applications. However, the surface of NCs and in particular their size-dependent capping organic ligand behavior, which play an important role in the NC synthesis, dispersibility, and optoelectronic properties, is still not well understood. We study the size-dependent properties of the ligand shell on the surface of NCs, by embedding surface bound dyes as a probe within the ligand shell. The reorientation times for these dyes show a linear dependence on the NC surface curvature indicating size-dependent change in viscosity, which is related to a change in the density of the ligand layer because of the geometry of the surface, a unique feature of NCs. Understanding the properties of the ligand shell will allow rational design of the surface to achieve the desired properties, providing an additional important knob for tuning their functionality.

  1. Efficiency of size-dependent particle separation by pinched flow fractionation

    CERN Document Server

    Srivastav, Aparna; Coupier, Gwennou

    2012-01-01

    Pinched flow fractionation is shown to be an efficient and selective way to quickly separate particles by size in a very polydisperse semi-concentrated suspension. In an effort to optimize the method, we discuss the quantitative influence of the pinching intensity in the balance between the requirements of selectivity and minimal dilution.

  2. Gold Nanoparticles Size Design and Control by Poly(N,N′-diethylaminoethyl methacrylate

    Directory of Open Access Journals (Sweden)

    Norma A. Cortez-Lemus

    2015-01-01

    Full Text Available Poly(N,N′-diethylaminoethyl methacrylate (PDEAEM with different molecular weights was used to stabilize gold nanoparticles (AuNPs obtained by in situ reduction of tetrachloroauric acid using citrates under acidic conditions and in organic/alcoholic medium. The influence of the pH value on gold nanoparticle size in the presence of PDEAEM was investigated. Results show that the pH of the reacting mixture has a dramatic effect on the size, polydispersity, and morphology of the resulting AuNPs. Moreover, the size of the nanoparticles (NPs may be modified by changing the solution’s pH or by changing the solvent type. Electron microscope images showed that the sizes of AuNPs coated with PDEAEM were not sensitive to the variation of the polymer molecular weight in the range between 9000 and 29300 g/mol; however their aggregation behavior depended strongly on the polymer molecular weight as revealed by dynamic light scattering studies. AuNPs stabilized with PDEAEM (AuNP@PDEAEM are stable in water at acidic pH and in organic polar solvents.

  3. A Note on "Stability of the Constant Cost Dynamic Lot Size Model" by K. Richter

    NARCIS (Netherlands)

    S. van Hoesel (Stan); A.P.M. Wagelmans (Albert)

    1991-01-01

    textabstractIn a paper by K. Richter the stability regions of the dynamic lot size model with constant cost parameters are analyzed. In particular, an algorithm is suggested to compute the stability region of a so-called generalized solution. In general this region is only a subregion of the stabili

  4. Damage localization in a residential-sized wind turbine blade by use of the SDDLV method

    DEFF Research Database (Denmark)

    Johansen, Rasmus Johan; Hansen, Lasse Majgaard; Ulriksen, Martin Dalgaard

    2015-01-01

    of the SDDLV method for localization of structural damages in a cantilevered residential-sized wind turbine blade. The blade was excited by an unmeasured multi-impulse load and the resulting dynamic response was captured through accelerometers mounted along the blade. The static pseudo-loads were applied...

  5. Ceramography and segmentation of polycristalline ceramics: application to grain size analysis by automatic methods

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, X.; Coster, M.; Chermant, J.L.; Chermant, L. [LERMAT, ISMRA, Caen (France); Chartier, T. [SPCTS, ENSCI, Limoges (France)

    2002-07-01

    The knowledge of the mean grain size of ceramics is a very important problem to solve in the ceramic industry. Some specific methods of segmentation are presented to analyse, by an automatic way, the granulometry and morphological parameters of ceramic materials. Example presented concerns cerine materials. Such investigations lead to important information on the sintering process. (orig.)

  6. M(H) dependence and size distribution of SPIONs measured by atomic magnetometry

    CERN Document Server

    Colombo, Simone; Grujic, Zoran D; Dolgovskiy, Vladimir; Weis, Antoine

    2016-01-01

    We demonstrate that the quasistatic recording of the magnetic excitation function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION) suspensions by an atomic magnetometer allows a precise determination of the sample's iron mass content mFe and the particle size distribution.

  7. Consequences of intraspecific seed-size variation in Sparganium emersum for dispersal by fish

    NARCIS (Netherlands)

    Pollux, B.J.A.; Ouborg, J.; Van Groenendael, J.M.; Klaassen, M.R.J.

    2007-01-01

    The potential for seed dispersal by fish (ichthyochory) is likely to vary within aquatic plant species, depending on intraspecific variation in phenotypic seed traits. 2. We studied the effect of seed size variation within the unbranched burreed (Sparganium emersum) on the potential for internal dis

  8. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae, E-mail: nicolae.leopold@phys.ubbcluj.ro [Babeş-Bolyai University, Faculty of Physics (Romania)

    2014-12-15

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl{sub 4} by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of ∼20 and ∼120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4–8 and 10–30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV–Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  9. Gold nanoparticle assemblies of controllable size obtained by hydroxylamine reduction at room temperature

    Science.gov (United States)

    Tódor, István Sz.; Szabó, László; Marişca, Oana T.; Chiş, Vasile; Leopold, Nicolae

    2014-12-01

    Colloidal nanoparticle assemblies (NPAs) were obtained in a one-step procedure, by reduction of HAuCl4 by hydroxylamine hydrochloride, at room temperature, without the use of any additional nucleating agent. By changing the order of the reactants, NPAs with mean size of 20 and 120 nm were obtained. Because of their size and irregular popcorn like shape, the larger size NPAs show absorption in the NIR spectral region. The building blocks of the resulted nanoassemblies are spherical nanoparticles with diameters of 4-8 and 10-30 nm, respectively. Moreover, by stabilizing the colloid with bovine serum albumin at different time moments after synthesis, NPAs of controlled size between 20 and 120 nm, could be obtained. The NPAs were characterized using UV-Vis spectroscopy, TEM and SEM electron microscopies. In addition, the possibility of using the here proposed NPAs as surface-enhanced Raman scattering (SERS) substrate was assessed and found to provide a higher enhancement compared to conventional citrate-reduced nanoparticles.

  10. Tuning the size and properties of ClyA nanopores assisted by directed evolution

    NARCIS (Netherlands)

    Soskine, Mikhael; Biesemans, Annemie; De Maeyer, Marc; Maglia, Giovanni

    2013-01-01

    Nanopores have recently emerged as powerful tools in single-molecule investigations. Biological nanopores, however, have drawbacks, including a fixed size and limited stability in lipid bilayers. Inspired by the great success of directed evolution approaches in tailoring enzyme properties, in this w

  11. Interdisciplinary Construction and Implementation of a Human sized Humanoid Robot by master students

    DEFF Research Database (Denmark)

    Helbo, Jan; Svendsen, Mads Sølver

    2009-01-01

    With limited funding it seemed a very good idea to encourage master students to design and construct their own human size biped robot.  Because this task is huge and very interdisciplinary different expertises were covered by students from different departments who in turn took over results from ...

  12. Fluorocarbon coatings deposited on micron-sized particles by atmospheric PECVD

    NARCIS (Netherlands)

    Abadjieva, E.; Heijden, A.E.D.M. van der; Creyghton, Y.L.M.; Ommen, J.R. van

    2012-01-01

    Fluorocarbon coatings have been deposited on micron-sized silica particles by means of atmospheric pressure plasma-enhanced chemical vapor deposition (PECVD). The silica particles have a diameter in the range between 40 and 70 ?m. They are fluidized at atmospheric pressure in a circulating fluidized

  13. Porous Carbon Fibers Containing Pores with Sizes Controlled at the Ångstrom Level by the Cavity Size of Pillar[6]arene.

    Science.gov (United States)

    Ogoshi, Tomoki; Yoshikoshi, Kumiko; Sueto, Ryuta; Nishihara, Hirotomo; Yamagishi, Tada-Aki

    2015-05-26

    We report a new synthesis method of fibrous carbon material with pores sizes that are precisely controlled at the Ångstrom level, by carbonization of two dimensional (2D) porous sheets of pillar[6]arenes. The 2D porous sheets were prepared by 2D supramolecular polymerization induced by oxidation of hydroquinone units of pillar[6]arenes. Owing to the hexagonal structure of pillar[6]arene, the assembly induced by 2D supramolecular polymerization gave hexagonal 2D porous sheets, and the highly ordered structure of the 2D porous sheets formed regular fibrous structures. Then, carbonization of the 2D porous sheets afforded fibrous carbon materials with micropores. The micropore size of the fibrous porous carbon prepared from pillar[6]arene was the same size as that of the starting material pillar[6]arene assembly.

  14. Tender for cleaning up business. New techniques and tender to reduce the emission of buses; Aanbesteding schoon busvervoer. Nieuwe technieken en aanbesteding bieden kansen voor emissiereductie bij bussen

    Energy Technology Data Exchange (ETDEWEB)

    Dorel, F.G.; Van den Broek, C.B.W.; Jansen, L. [Provincie Zuid-Holland, The Hague (Netherlands)

    2000-03-01

    Air pollution in urban areas in the Netherlands still causes health-problems, and the present air quality does not meet the new standards in the European Union. Every part of society (industry, traffic etc.) therefore has to contribute in reducing emissions. Regarding buses there are several options. New buses can be build with an engine suitable for LPG, or new and existing diesel buses can be equipped with so called 'Continuous Regenerating Traps' (CRT-filters). This article focuses on the new possibility of provinces and municipalities in the Netherlands to facilitate the introduction of these new techniques. For the first time, these governments are planning to call for tenders of bus companies publicly. In order to be granted permission to provide public transport in a certain area, a bus company has to agree upon reducing its present average bus emissions to a certain (fixed) extent. 10 refs.

  15. Aerosol Size Distribution in a City Influenced by Both Rural and Urban Regions

    Science.gov (United States)

    Fitzgerald, R. M.; Polanco, J.; Lozano, A.

    2006-12-01

    Most atmospheric studies have focused on sites located in either rural or urban areas. However, there are regions affected by air from both, such as the city of El Paso. Adjacent to the neighboring city of Juarez, Mexico, and in close proximity to rural areas, it is affected by desert particles and both biogenic, anthropogenic emissions. Aerosol properties largely depend upon particle size and this makes it the most important parameter for characterizing the aerosol. We focus on studies using inverse reconstruction models for particle size distribution using aerosol optical depth data. Our methodology uses Twomey's regularization technique that suppresses ill-posedness by imposing smoothing and non-negativity constraints on the desired size distributions. We have also applied T-matrix codes to study the scattering from irregularly shaped particles that exhibit rotational symmetry. Furthermore, our studies include analysis of aerosol size distributions using optic probes and soot photometers, sampled from aircraft at different heights. This work will lead to better characterization of aerosols and their impact in our rural-urban interface region. In addition, it will provide a more accurate assessment of regional transport and better boundary conditions for air quality models.

  16. Modification of foaming properties of soy protein isolate by high ultrasound intensity: Particle size effect.

    Science.gov (United States)

    Morales, Rocío; Martínez, Karina D; Pizones Ruiz-Henestrosa, Víctor M; Pilosof, Ana M R

    2015-09-01

    The effect of high intensity ultrasound (HIUS) may produce structural modifications on proteins through a friendly environmental process. Thus, it can be possible to obtain aggregates with a determined particle size, and altering a defined functional property at the same time. The objective of this work was to explore the impact of HIUS on the functionality of a denatured soy protein isolate (SPI) on foaming and interfacial properties. SPI solutions at pH 6.9 were treated with HIUS for 20 min, in an ultrasonic processor at room temperature, at 75, 80 and 85°C. The operating conditions were: 20 kHz, 4.27 ± 0.71 W and 20% of amplitude. It was determined the size of the protein particles, before and after the HIUS treatment, by dynamic light scattering. It was also analyzed the interfacial behavior of the different systems as well as their foaming properties, by applying the whipping method. The HIUS treatment and HIUS with temperature improved the foaming capacity by alteration of particle size whereas stability was not modified significantly. The temperature of HIUS treatment (80 and 85°C) showed a synergistic effect on foaming capacity. It was found that the reduction of particle size was related to the increase of foaming capacity of SPI. On the other hand, the invariable elasticity of the interfacial films could explain the stability of foams over time.

  17. Size Characterization of Colloidal Platinum Nanoparticles by MALDI-TOF Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Navin, Jason K.; Grass, Michael E.; Somorjai, Gabor A.; Marsh, Anderson L.

    2009-08-15

    In this work, matrix assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) has been utilized to characterize colloidal platinum nanoparticles synthesized in the 1-4 nm size range. The nanoparticles were prepared via a solution-based method in which the size could be controlled by varying reaction conditions, such as the alcohol used as the reductant. Poly(vinylpyrrolidone), or PVP, (MW = 29,000 g/mol) was employed as a capping agent to stabilize the synthesized nanoparticles in solution. A model for determining the size of the metallic nanoparticle core from MALDI-TOF mass spectra has been developed and verified through correlation with particle sizes from transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements. In this model it was assumed that 1.85 nm nanoparticles are capped by one PVP chain, which was verified through experiments performed with capped and uncapped nanoparticles. Larger nanoparticles are capped by either two (2.60 and 2.94 nm) or three (3.69 nm) PVP chains. These findings clearly indicate the usefulness of MALDI-TOF MS as a technique for fully characterizing nanoscale materials in order to elucidate structure-property relationships.

  18. Not only size matters: Acorn selection by the European jay ( Garrulus glandarius)

    Science.gov (United States)

    Pons, Josep; Pausas, Juli G.

    2007-05-01

    A strong selection for acorn characteristics is expected to have evolved in the mutualistic relationship between the European jay ( Garrulus glandarius) and the oak ( Quercus spp.). Bossema's pioneer work suggested that jays do not select acorns randomly, but rather they preferentially select some size and species. Preference for some seeds over others may have implications on plant community dynamics by conferring advantages (or disadvantages) on the selected (avoided) seed characteristics. In this paper we test to what extent jays select acorns by species and/or by size and the relation between these two traits in Mediterranean oak species. The experiments consist of a set of field tests in which acorns from four different coexisting Mediterranean oak species ( Quercus ilex, Quercus faginea, Quercus suber, and Quercus coccifera) were placed in artificial feeders accessible to wild jays. The acorns were previously measured to control individual acorn characteristics. Using video-recording techniques, we followed jay activity and the fate of each acorn (sequence of acorn selection and method of transport). Q. ilex acorns were preferred over other acorns, and Q. coccifera acorns were avoided when other acorns were available. Preference for Q. faginea and Q. suber acorns was intermediate, that is, they were preferred over Q. coccifera acorns but not over Q. ilex acorns. Large acorns were also preferred although acorn species selection was stronger than size selection. Jays selected species and size both by visual means and by using acorn area as an indicator of size. Acorns wider than 17-19 mm were carried in the bill because of throat limitation. Our results confirm Bossema's study on temperate oaks and extend it to Mediterranean oak species, revealing implications on mixed oak forest dynamics.

  19. New energy-saving and environmentally friendly technologies for buses and trucks; Nieuwe energiezuinige en milieuvriendelijke technologien voor bussen en vracthtwagens

    Energy Technology Data Exchange (ETDEWEB)

    Craps, R.; De Keukeleere, D.; Lenaers, G.

    1998-09-01

    The point of departure was the statement that people find public transport buses highly polluting. A lot of attention went to the advantages and the disadvantages of buses and trucks on liquefied petroleum gas (LPG) and natural gas. These fuels don`t cause any particle emissions from the combustion process. To quantify the other environmental advantages of gas technology, the Flemish Institute for Technological Research (VITO) carried out measurements of different bus technologies. Fuel consumption, emission of nitrogen oxides, carbon monoxides and hydrocarbons of 8 buses were measured in the Brussels traffic. 3 technologies of the early nineties were taken as a reference: the Euro-1 diesel, the current Brussels public transport company natural gas bus and a LPG bus. Comparisons were made with the modern diesel bus (Euro-2) and the newest buses on natural gas and LPG. To achieve minimal emissions, the best available technology for buses on natural gas or LPG is multipoint injection, the constructors of engines for heavy-duty traffic are changing from carburetor to fuel injection. The best available gas technologies has emissions that can be 50 to 95 per cent lower than the most modern diesel bus. Users mentioned problems at the introduction of vehicles on gas, such as lower reliability and availability. The cost price continues to be a disadvantage of buses and trucks on gas. The extra consumption of fuel doesn`t necessarily imply higher costs. Often fuel suppliers and distributors offer a favourable unit price, which includes the cost for the infrastructure. The purchase price of the vehicle remains higher and the workplaces must be adjusted for maintenance and repairs of vehicles on gas. The bus or truck on diesel is very reliable and cheaper to use than a similar vehicle on gas. The environmental perspectives are much less marked. Heavy-duty traffic emits nitrogen oxides and particles. With respect to these harmful substances in particular, constructors must

  20. 氨法制取纳米氧化锌的粒径控制研究%Particle size control of nano - sized zinc oxide by ammonia process

    Institute of Scientific and Technical Information of China (English)

    蔡建国; 蔡睿敏

    2009-01-01

    为有效控制氨法制取纳米氧化锌的粒径,在蒸氨前将浸出原液用一定量的纯净水稀释,可增加初期沉淀生成的晶核数,使沉淀粒径更加均匀和细化,同时发现蒸氨残液不可以作为浸出原液的稀释剂回用.蒸氨的加热方式对纳米氧化锌的粒径也有影响,选择蒸汽直接加热,当溶液含锌质量浓度小于0.3 g/L时,所制取的纳米氧化锌粒径满足GB/T 19589-2004纳米氧化锌的要求 .%In order to effectively control the particle size of nano - sized zinc oxide prepared by ammonia process,leaching stock solution was diluted with a certain amount of purified water before ammonia distillation process,which could increase the quantity of crystal nucleus generated by initial precipitation and make particle size of precipitate more uniform and refined.Meanwhile,it was found that distilled ammonia residual liquid could not be served as diluent of leaching stock solution for recycling.Also,heating method of ammonia distillation will affect the particle size of nano - sized zinc oxide.Particle size of prepared nano - sized zinc oxide can satisfy the requirements of GB/T 19589-2004,when direct steam heating was selected and mass concentration of zinc in the solution was less than 0.3 g/L.

  1. Seed size variation and predation of seeds produced by wild and crop-wild sunflowers.

    Science.gov (United States)

    Alexander, H M; Cummings, C L; Kahn, L; Snow, A A

    2001-04-01

    The movement of pollen between crop and wild sunflowers (both Helianthus annuus) has led to concerns about the possible introduction of crop transgenes into wild populations. The persistence of crop traits in wild populations will depend in part on the relative fitness of crop-wild hybrid vs. wild plants. Using seeds from two large experimental field plots, we found that seeds produced by crop-wild plants were twice the size of wild seeds and differed in coloration. Head diameter, date of flowering, identity of mother plant, and levels of predispersal predation explained some variation in mean seed size. We hypothesized that postdispersal vertebrate seed predation would be affected by seed size, with hybrid seeds preferentially eaten. In each of three field trials, significantly more hybrid seeds were eaten (62% of hybrid seed; 42% of wild seed). Within the category of wild seeds, larger seeds were preferentially eaten; however among hybrid seeds, predation was not significantly related to seed size. In this study, differential predation thus reduces hybrid fitness and would presumably slow the spread of transgenes into wild populations.

  2. Size-Controlled and Optical Properties of Monodispersed Silver Nanoparticles Synthesized by the Radiolytic Reduction Method

    Directory of Open Access Journals (Sweden)

    Kazem Naghavi

    2013-04-01

    Full Text Available Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum λmax blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0 to higher energy states (n ≥ 6; Δl = 0, ±1; Δs = 0, ±1, allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology.

  3. Molecular behavior of DNA in a cell-sized compartment coated by lipids

    CERN Document Server

    Hamada, T; Shimobayashi, S F; Ichikawa, M; Takagi, M

    2015-01-01

    The behavior of long DNA molecules in a cell-sized confined space was investigated. We prepared water-in-oil droplets covered by phospholipids, which mimic the inner space of a cell, following the encapsulation of DNA molecules with unfolded coil and folded globule conformations. Microscopic observation revealed that the adsorption of coiled DNA onto the membrane surface depended on the size of the vesicular space. Globular DNA showed a cell-size-dependent unfolding transition after adsorption on the membrane. Furthermore, when DNA interacted with a two-phase membrane surface, DNA selectively adsorbed on the membrane phase, such as an ordered or disordered phase, depending on its conformation. We discuss the mechanism of these trends by considering the free energy of DNA together with a polyamine in the solution. The free energy of our model was consistent with the present experimental data. The cooperative interaction of DNA and polyamines with a membrane surface leads to the size-dependent behavior of molec...

  4. Size sorting of citrate reduced gold nanoparticles by sedimentation field-flow fractionation.

    Science.gov (United States)

    Contado, Catia; Argazzi, Roberto

    2009-12-25

    Gold nanoparticles (GNPs) have been synthesized through the citrate reduction method; the citrate/gold(III) ratio was changed from 1:1 up to 10:1 and the size of the resulting nanoparticles was measured by sedimentation field-flow fractionation (SdFFF). Experimental data showed that the GNPs size decreases in the ratio range 1:1-3:1 and then increases from 5:1 to 10:1 passing through a plateau region in between, and is almost independent of the precursor solution concentrations. In the zone of minimum diameters the synthetic process does not produce monodispersed GNPs but often multiple distributions, very close in size, are observed as evidenced by the particle size distributions (PSDs) derived from the SdFFF fractograms. UV-vis spectrophotometry, being the most common technique employed in the optical characterization of nanoparticles suspensions, was used throughout this work. A confirmation of the nucleation-aggregation-fragmentation mechanism was inferred from the cross-correlation between UV-vis and SdFFF results.

  5. Fluorescence quenching of fluoroquinolones by gold nanoparticles with different sizes and its analytical application

    Energy Technology Data Exchange (ETDEWEB)

    Amjadi, Mohammad, E-mail: amjadi@tabrizu.ac.ir; Farzampour, Leila

    2014-01-15

    The interaction of some fluoroquinolones including norfloxacin, ciprofloxacin, danofloxacin and ofloxacin with gold nanoparticles (AuNPs) of different sizes (8, 20 and 75 nm) was studied. In the studied systems, fluoroquinolones are noncovalently adsorbed onto the surface of AuNPs, which results in severe quenching of fluoroquinolones fluorescence possibly as a result of fluorescence resonance energy transfer. Stern–Volmer quenching constants were obtained and found to increase with an increase in the size of AuNPs. Moreover, the interactions between some thiols and fluoroquinolone-adsorbed AuNPs were investigated to explore the analytical applicability of the systems. It was found that upon the addition of thiols to fluoroquinolone-AuNPs systems the fluorescence of fluoroquinolones switches to “turn-on” due to the strong binding of thiols to AuNPs and removal of quinolines from NP surface. Under the optimum conditions, the fluorescence enhancement showed a linear relationship with the concentration of thiols, indicating the analytical usefulness of the system. -- Highlights: • Interaction of fluoroquinolones with AuNPs of different sizes was investigated. • The fluorescence of fluoroquinolones is efficiently quenched by AuNPs. • The fluorescence quenching efficiency increases by increasing NP size. • Fluoroquinolone-AuNPs systems can be used as sensitive turn-on sensors for thiols. • Danofloxacin-20-nm AuNPs system exhibits the highest sensitivity for thiols.

  6. Surface plasmon enhanced photoluminescence in amorphous silicon carbide films by adjusting Ag island film sizes

    Institute of Scientific and Technical Information of China (English)

    Yu Wei; Wang Xin-Zhan; Dai Wan-Lei; Lu Wan-Bing; Liu Yu-Mei; Fu Guang-Sheng

    2013-01-01

    Ag island films with different sizes are deposited on hydrogenated amorphous silicon carbide (α-SiC∶H) films,and the influences of Ag island films on the optical properties of the α-SiC∶H films are investigated.Atomic force microscope images show that Ag nanoislands are formed after Ag coating,and the size of the Ag islands increases with increasing Ag deposition time.The extinction spectra indicate that two resonance absorption peaks which correspond to out-of-plane and in-plane surface plasmon modes of the Ag island films are obtained,and the resonance peak shifts toward longer wavelength with increasing Ag island size.The photoluminescence (PL) enhancement or quenching depends on the size of Ag islands,and PL enhancement by 1.6 times on the main PL band is obtained when the sputtering time is 10 min.Analyses show that the influence of surface plasmons on the PL of α-SiC:H is determined by the competition between the scattering and absorption of Ag islands,and PL enhancement is obtained when scattering is the main interaction between the Ag islands and incident light.

  7. Activation of Big Grain1 significantly improves grain size by regulating auxin transport in rice.

    Science.gov (United States)

    Liu, Linchuan; Tong, Hongning; Xiao, Yunhua; Che, Ronghui; Xu, Fan; Hu, Bin; Liang, Chengzhen; Chu, Jinfang; Li, Jiayang; Chu, Chengcai

    2015-09-01

    Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population. Overexpression of BG1 leads to significantly increased grain size, and the severe lines exhibit obviously perturbed gravitropism. In addition, the mutant has increased sensitivities to both auxin and N-1-naphthylphthalamic acid, an auxin transport inhibitor, whereas knockdown of BG1 results in decreased sensitivities and smaller grains. Moreover, BG1 is specifically induced by auxin treatment, preferentially expresses in the vascular tissue of culms and young panicles, and encodes a novel membrane-localized protein, strongly suggesting its role in regulating auxin transport. Consistent with this finding, the mutant has increased auxin basipetal transport and altered auxin distribution, whereas the knockdown plants have decreased auxin transport. Manipulation of BG1 in both rice and Arabidopsis can enhance plant biomass, seed weight, and yield. Taking these data together, we identify a novel positive regulator of auxin response and transport in a crop plant and demonstrate its role in regulating grain size, thus illuminating a new strategy to improve plant productivity.

  8. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering

    Science.gov (United States)

    Ma, Teng; Liu, Zhibo; Wen, Jinxiu; Gao, Yang; Ren, Xibiao; Chen, Huanjun; Jin, Chuanhong; Ma, Xiu-Liang; Xu, Ningsheng; Cheng, Hui-Ming; Ren, Wencai

    2017-02-01

    Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation-adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ~200 nm to ~1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ~3.8 × 109 W m-2 K-1, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ~0.01 eV and resistivity of ~0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials.

  9. Evaluation of the use of bioethanol fuelled buses based on ambient air pollution screening and on-road measurements.

    Science.gov (United States)

    López-Aparicio, S; Hak, C

    2013-05-01

    Mitigation measures to reduce greenhouse gas emissions may have adverse effects on urban air quality and human exposure to harmful pollutants. The use of bioethanol fuelled vehicles is increasing worldwide and may create new undesired pollution effects. Different measurement campaigns were performed in a pilot study to contribute to the understanding of the consequences associated with the use of bioethanol blended fuel (E95) on a series of pollutants. Ambient screening measurements of NO2, O3, acetic acid, formaldehyde and acetaldehyde were performed at different urban locations, exposed and not exposed to the circulation of bioethanol buses. In addition, volatile organic compounds were measured at the exhaust pipe of a bioethanol fuelled bus, both under idling conditions (carbonyls; DNPH cartridge) and under on-road driving conditions applying online monitoring (PTR-TOF). Higher ambient acetaldehyde values were measured at locations exposed to bioethanol fuelled buses than at locations not exposed, and very high acetaldehyde and acetic acid values were measured from the exhaust pipe during driving conditions (acetaldehyde>150 ppm; acetic acid ≈ 20-30 ppm) and modelled at close distance to the bioethanol bus. Human exposure to high concentration of acetaldehyde is expected, and it may involve a significantly increased chance in developing cancer. The high concentration of acetic acid will involve odour annoyance and significant material degradation or corrosion.

  10. Estimate of sizes of small asteroids (cosmic bodies) by the method of stroboscopic radiolocation

    CERN Document Server

    Zakharchenko, V D; Pak, O V

    2014-01-01

    Radiolocation methods of probing minor celestial bodies (asteroids) by the nanosecond pulses can be used for monitoring of near-Earth space with the purpose of identification of hazardous cosmic objects able to impact the Earth. Development of the methods that allow to improve accuracy of determining the asteroids size (i.e. whether it measures tens or hundreds meters in diameter) is important for correctly estimating the degree of damage which they can cause (either regional or global catastrophes, respectively). In this paper we suggest a novel method of estimating the sizes of the passive cosmic objects using the radiolocation probing by ultra-high-resolution nanosecond signals to obtain radar signatures. The modulation envelope of the reflected signal, which is a radar portrait of the cosmic object, is subjected to time scale transformation to carrier Doppler frequency by means of radioimpulse strobing. The shift of a strobe within the probing period will be performed by radial motion of the object which ...

  11. Urban air quality improvement by using a CNG lean burn engine for city buses

    NARCIS (Netherlands)

    Merétei, T.; Ling, J.A.N. van; Havenith, C.

    1998-01-01

    The use of compressed natural gas (CNG)-fuelled lean-burn city bus engines has a significant potential for air quality improvement in urban areas. Particularly important is the reduction of NO, as well as particulate and non regulated HC-emissions. For this reason, a CNG-fuelled, lean-burn, turbocha

  12. Particle Size and Pore Structure Characterization of Silver Nanoparticles Prepared by Confined Arc Plasma

    Directory of Open Access Journals (Sweden)

    Mingru Zhou

    2009-01-01

    Full Text Available In the protecting inert gas, silver nanoparticles were successfully prepared by confined arc plasma method. The particle size, microstructure, and morphology of the particles by this process were characterized via X-ray powder diffraction (XRD, transmission electron microscopy (TEM and the corresponding selected area electron diffraction (SAED. The N2 absorption-desorption isotherms of the samples were measured by using the static volumetric absorption analyzer, the pore structure of the sample was calculated by Barrett-Joyner-Halenda (BJH academic model, and the specific surface area was calculated from Brunauer-Emmett-Teller (BET adsorption equation. The experiment results indicate that the crystal structure of the samples is face-centered cubic (FCC structure the same as the bulk materials, the particle size distribution ranging from 5 to 65 nm, with an average particle size about 26 nm obtained by TEM and confirmed by XRD and BET results. The specific surface area is 23.81 m2/g, pore volumes are 0.09 cm3/g, and average pore diameter is 18.7 nm.

  13. Optimization of size controlled poly (lactide-co-glycolic acid nanoparticles using quality by design concept

    Directory of Open Access Journals (Sweden)

    Padmanabha R. V. Reddy

    2015-01-01

    Full Text Available Quality by design (QbD is a risk management and science-based approach laid down by the ICH as well as other Regulatory agencies to enhance pharmaceutical development throughout a product′s lifecycle. Poly(lactide-co-glycolic acid (PLGA is the material of choice for development of depot particulate formulations due to its biodegradable nature and is also considered as the ′green′ eco-friendly material due its biocompatibility and non-toxic properties. Further, PLGA based formulations are approved by regulatory agencies and currently in clinical practice. The aim of the current investigation involves formulation, optimization and in vitro characterization of size controlled PLGA based nanoparticles by employing modified nanoprecipitation technique. An initial risk-assessment analysis was conducted with different formulation and process variables along with their impact on critical quality attributes of the formulation which were identified as particle size and percentage process yield. The Ishikawa diagram was employed to determine the potential risk factors and subsequently optimized by statistical experimental design concept. Box-Behnken design was utilized to optimize nanoparticles and further characterizing the optimized nanoparticulate formulation in vitro. From the present study, it can be concluded that PLGA based nanoparticles with controlled particle size and process yield can be obtained by inculcating the concept of QbD in the product development.

  14. Determination of particle size distribution and elastic properties of silica microcapsules by ultrasound spectroscopy

    Science.gov (United States)

    Nguyen Tran, Thao; Shibata, Daisuke; Norisuye, Tomohisa; Nakanishi, Hideyuki; Tran-Cong-Miyata, Qui

    2016-07-01

    The acoustical properties of silica microcapsules synthesized by the interfacial polymerization of sodium silicate were studied by ultrasound spectroscopy. The experimental data were reproduced by the Waterman-Truell dispersion relation with the scattering function theory proposed by Goodman and Stern for hollow particles in liquid. The particle size distributions were successfully evaluated by the analysis and were found to be in good agreement with those obtained by scanning electron microscopy (SEM). The formation of such silicate microcapsules synthesized through water/oil/water emulsion as a template was also monitored.

  15. Arabidopsis haiku mutants reveal new controls of seed size by endosperm.

    Science.gov (United States)

    Garcia, Damien; Saingery, Virginie; Chambrier, Pierre; Mayer, Ulrike; Jürgens, Gerd; Berger, Frédéric

    2003-04-01

    In flowering plants, maternal seed integument encloses the embryo and the endosperm, which are both derived from double fertilization. Although the development of these three components must be coordinated, we have limited knowledge of mechanisms involved in such coordination. The endosperm may play a central role in these mechanisms as epigenetic modifications of endosperm development, via imbalance of dosage between maternal and paternal genomes, affecting both the embryo and the integument. To identify targets of such epigenetic controls, we designed a genetic screen in Arabidopsis for mutants that phenocopy the effects of dosage imbalance in the endosperm. The two mutants haiku 1 and haiku 2 produce seed of reduced size that resemble seed with maternal excess in the maternal/paternal dosage. Homozygous haiku seed develop into plants indistinguishable from wild type. Each mutation is sporophytic recessive, and double-mutant analysis suggests that both mutations affect the same genetic pathway. The endosperm of haiku mutants shows a premature arrest of increase in size that causes precocious cellularization of the syncytial endosperm. Reduction of seed size in haiku results from coordinated reduction of endosperm size, embryo proliferation, and cell elongation of the maternally derived integument. We present further evidence for a control of integument development mediated by endosperm-derived signals.

  16. Acoustophoretic separation of airborne millimeter-size particles by a Fresnel lens

    Science.gov (United States)

    Cicek, Ahmet; Korozlu, Nurettin; Adem Kaya, Olgun; Ulug, Bulent

    2017-01-01

    We numerically demonstrate acoustophoretic separation of spherical solid particles in air by means of an acoustic Fresnel lens. Beside gravitational and drag forces, freely-falling millimeter-size particles experience large acoustic radiation forces around the focus of the lens, where interplay of forces lead to differentiation of particle trajectories with respect to either size or material properties. Due to the strong acoustic field at the focus, radiation force can divert particles with source intensities significantly smaller than those required for acoustic levitation in a standing field. When the lens is designed to have a focal length of 100 mm at 25 kHz, finite-element method simulations reveal a sharp focus with a full-width at half-maximum of 0.5 wavelenghts and a field enhancement of 18 dB. Through numerical calculation of forces and simulation of particle trajectories, we demonstrate size-based separation of acrylic particles at a source sound pressure level of 153 dB such that particles with diameters larger than 0.5 mm are admitted into the central hole, whereas smaller particles are rejected. Besides, efficient separation of particles with similar acoustic properties such as polyethylene, polystyrene and acrylic particles of the same size is also demonstrated. PMID:28252033

  17. Blood clot initiation by mesocellular foams: dependence on nanopore size and enzyme immobilization.

    Science.gov (United States)

    Baker, Sarah E; Sawvel, April M; Fan, Jie; Shi, Qihui; Strandwitz, Nicholas; Stucky, Galen D

    2008-12-16

    Porous silica materials are attractive for hemorrhage control because of their blood clot promoting surface chemistry, the wide variety of surface topologies and porous structures that can be created, and the potential ability to achieve high loading of therapeutic proteins within the silica support. We show that silica cell-window size variation in the nanometers to tens of nanometers range greatly affects the rate at which blood clots are formed in human plasma, indicating that window sizes in this size range directly impact the accessibility and diffusion of clotting-promoting proteins to and from the interior surfaces and pore volume of mesocellular foams (MCFs). These studies point toward a critical window size at which the clotting speed is minimized and serve as a model for the design of more effective wound-dressing materials. We demonstrate that the clotting times of plasma exposed to MCF materials are dramatically reduced by immobilizing thrombin in the pores of the MCF, validating the utility of enzyme-immobilized mesoporous silicas in biomedical applications.

  18. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    Science.gov (United States)

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; van der Laan, G.; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-11-01

    The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

  19. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens

    Energy Technology Data Exchange (ETDEWEB)

    Byrne, J. M.; Telling, N. D.; Coker, V. S.; Pattrick, R. A. D.; Laan, G. van der; Arenholz, E.; Tuna, F.; Lloyd, J. R.

    2011-08-02

    The bioproduction of nano-scale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens, by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles has been investigated by X-ray magnetic circular dichroism and indicates the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimised biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently in the less harmful trivalent form.

  20. Control of nanoparticle size, reactivity and magnetic properties during the bioproduction of magnetite by Geobacter sulfurreducens.

    Science.gov (United States)

    Byrne, J M; Telling, N D; Coker, V S; Pattrick, R A D; van der Laan, G; Arenholz, E; Tuna, F; Lloyd, J R

    2011-11-11

    The bioproduction of nanoscale magnetite by Fe(III)-reducing bacteria offers a potentially tunable, environmentally benign route to magnetic nanoparticle synthesis. Here, we demonstrate that it is possible to control the size of magnetite nanoparticles produced by Geobacter sulfurreducens by adjusting the total biomass introduced at the start of the process. The particles have a narrow size distribution and can be controlled within the range of 10-50 nm. X-ray diffraction analysis indicates that controlled production of a number of different biominerals is possible via this method including goethite, magnetite and siderite, but their formation is strongly dependent upon the rate of Fe(III) reduction and total concentration and rate of Fe(II) produced by the bacteria during the reduction process. Relative cation distributions within the structure of the nanoparticles have been investigated by x-ray magnetic circular dichroism and indicate the presence of a highly reduced surface layer which is not observed when magnetite is produced through abiotic methods. The enhanced Fe(II)-rich surface, combined with small particle size, has important environmental applications such as in the reductive bioremediation of organics, radionuclides and metals. In the case of Cr(VI), as a model high-valence toxic metal, optimized biogenic magnetite is able to reduce and sequester the toxic hexavalent chromium very efficiently to the less harmful trivalent form.

  1. Particle size control of LiCoO{sub 2} powders by powder engineering methods

    Energy Technology Data Exchange (ETDEWEB)

    Shlyakhtin, O.A. [Korea Inst. of Science and Technology, Seoul (Korea). Materials Science and Technology Division; Moscow State Univ. (Russian Federation). Dept. of Chemistry; Young Soo Yoon; Young Jei Oh [Korea Inst. of Science and Technology, Seoul (Korea). Materials Science and Technology Division

    2003-10-01

    The directed influence on the micromorphology of precursors during preparation of lithium cobaltate powders by chemical synthesis methods allows to control the size of LiCoO{sub 2} crystallites from 4-6 {mu}m to 60-100 nm. Localization of melting during thermolysis by mixing acetate precursors with foaming agents promotes the reduction of grain size from 4-6 down to 1-1.5 {mu}m. More efficient prevention of grain coalescence can be performed by introducing a thermally stable inert encapsulation agent (K{sub 2}SO{sub 4}) removed by dissolution after thermal processing. The combination of this method with intense deagglomeration of precursor mixtures by planetary milling results in keeping the grain size at the level of primary LiCoO{sub 2} particles (60-80 nm) even at T=800 {sup o}C. Intense mechanical processing of as-formed LiCoO{sub 2} powders is undesirable due to negative influence on the crystallographic ordering processes. (author)

  2. Predicting size effect on diffusion-limited current density of oxygen reduction by copper wire

    Institute of Scientific and Technical Information of China (English)

    LU Yonghong; XU Haibo; WANG Jia; ZHONG Lian

    2011-01-01

    The size effect of copper wire radius (0.04鈥?.82 mm) on the diffusion-limited current density of an oxygen reduction reaction in stagnant simulated seawater (naturally aerated 0.5 mol/L NaCl) is investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and compared with the results obtained in 0.5 mol/L H2SO4. In the oxygen diffusion-limited range, size effect is found to occur independent of electrolytes, which is attributed to non-linear diffusion. Additionally, to satisfy application in a marine setting, an empirical equation correlating oxygen diffusion-limited current density to copper wire radius is proposed by fitting experimental data.

  3. Transient increase of intact visual field size by high-frequency narrow-band stimulation.

    Science.gov (United States)

    Elliott, Mark A; Seifert, Doerthe; Poggel, Dorothe A; Strasburger, Hans

    2015-03-01

    Three patients with visual field defects were stimulated with a square matrix pattern, either static, or flickering at frequencies that had been found to either promote or not promote blindsight performance. Comparison between pre- and post-stimulation perimetric maps revealed an increase in the size of the intact visual field but only for flicker frequencies previously found to promote blindsight. These changes were temporary but dramatic - in two instances the intact field was increased by an area of ∼30 deg(2) of visual angle. These results indicate that not only does specific high-frequency stimulus flicker promote blindsight, but that intact visual field size may be increased by stimulation at the same frequencies. Our findings inform speculation on both the brain mechanisms and the potency of temporal modulation for altering the functional visual field.

  4. Aero particles characterization emitted by mobile sources;Caracterizacion de aeroparticulas emitidas por fuentes moviles

    Energy Technology Data Exchange (ETDEWEB)

    Rojas V, A.; Romero G, E. T.; Lopez G, H., E-mail: elizabeth.romero@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    In our country, the mobile sources that conform most of the emissions at the atmosphere, are concentrated on the urban areas. For the present work, samples coming from the escapes of terrestrial transport were obtained, such as: passenger buses, load transport and particular vehicles of the Metropolitan area of the Toluca valley. The material was analyzed by means of scanning electron microscopy of low vacuum and X-ray diffraction. The objective was to characterize the emitted particles by mobile sources, morphological and chemically to know the structure, size and elements that compose them. (Author)

  5. Assessment of left ventricular function by GPs using pocket-sized ultrasound

    OpenAIRE

    Mjølstad, Ole Christian; Snare, Sten Roar; Folkvord, Lasse; Helland, Frode; Grimsmo, Anders; Torp, Hans; Haraldseth, Olav; Haugen, Bjørn Olav

    2012-01-01

    Background Assessment of left ventricular (LV) function with echocardiography is mandatory in patients with suspected heart failure (HF). Objectives To investigate if GPs were able to evaluate the LV function in patients at risk of developing or with established HF by using pocket-sized ultrasound (pUS). Methods Feasibility study in general practice, seven GPs in three different Norwegian primary care centres participated. Ninety-two patients with reduced or at risk of developing reduced LV f...

  6. Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

    OpenAIRE

    Giraud, Isabelle; Franceschi-Messant, Sophie; Perez, Emile; Lacabanne, Colette; Dantras, Eric

    2013-01-01

    International audience; In this work, different sizing agent aqueous dispersions based on polyetherimide (PEI) were elaborated in order to improve the interface between carbon fibers and a thermoplastic matrix (PEEK). The dispersions were obtained by the emulsion/solvent evaporation technique. To optimize the stability and the film formation on the fibers, two surfactants were tested at different concentrations, with different concentrations of PEI. The dispersions obtained were characterized...

  7. Droplet size prediction in the production of drug delivery microsystems by ultrasonic atomization

    OpenAIRE

    2013-01-01

    Microencapsulation processes of drugs or other functional molecules are of great interest in pharmaceutical production fields. Ultrasonic assisted atomization is a new technique to produce microencapsulated systems by mechanical approach. It seems to offer several advantages (low level of mechanical stress in materials, reduced energy request, reduced apparatuses size) with respect to more conventional techniques. In this paper the groundwork of atomization is briefly introduced and correlati...

  8. Movement of a millimeter-sized oil drop pushed by optical force

    Institute of Scientific and Technical Information of China (English)

    张莉; 佘卫龙

    2015-01-01

    We show experimentally that when an unfocused continuous wave (CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oil drop, making it move forwards along the surface of the sucrose solution. However, after a period of time, the oil drop stops moving. This can be explained as the phenomenon caused by the change of Abraham momentum, the optical gradient force, and friction together.

  9. Mathematical modeling of polystyrene particle size distribution produced by suspension polymerization

    Directory of Open Access Journals (Sweden)

    Machado R.A.F.

    2000-01-01

    Full Text Available Particle size distribution (PSD of polystyrene particles produced by suspension polymerization is of fundamental importance in determining suspension stability and product quality attributes. Within a population balance framework, a model is proposed for suspension polymerization reactors to describe the evolution of the PSD. The model includes description of breakage and coalescence rates in terms of reaction kinetics and rheology of the dispersed phase. The model is validated with experimental data of styrene suspension polymerization.

  10. Influence of Size of Hematite Powder on Its Reduction Kinetics by H2 at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    PANG Jian-ming; GUO Pei-min; ZHAO Pei; CAO Chao-zhen; ZHANG Dian-wei

    2009-01-01

    The reduction kinetics and mechanisms of hematite ore with various particle sizes with hydrogen at low temperature were studied using the thermogravimetric analysis. At the same temperature, after the particle size of powder decreases from 107.5 μm to 2. 0 μm, the surface area of the powder and the contact area between the powder and gas increase, which makes the reduction process of hematite accelerate by about 8 times, and the apparent activation energy of the reduction reaction drops to 36.9 kJ/mol from 78.3 kJ/mol because the activity of ore powder is improved by refining gradually. With the same reaction rate, the reaction temperature of 6. 5 μm powder decreases by about 80 ℃ compared with that of 107.5 μm powder. Thinner diffusion layer can also accelerate the reaction owing to powder refining. The higher the temperature, the greater is the peak of the reduction rates at the same temperature, the greater the particle size, the smaller is the peak value of the reduction rates both inner diffusion and inter-face chemical reaction play an important role in the whole reaction process.

  11. Analytical Approach for Loss Minimization in Distribution Systems by Optimum Placement and Sizing of Distributed Generation

    Directory of Open Access Journals (Sweden)

    Bakshi Surbhi

    2016-01-01

    Full Text Available Distributed Generation has drawn the attention of industrialists and researchers for quite a time now due to the advantages it brings loads. In addition to cost-effective and environmentally friendly, but also brings higher reliability coefficient power system. The DG unit is placed close to the load, rather than increasing the capacity of main generator. This methodology brings many benefits, but has to address some of the challenges. The main is to find the optimal location and size of DG units between them. The purpose of this paper is distributed generation by adding an additional means to reduce losses on the line. This paper attempts to optimize the technology to solve the problem of optimal location and size through the development of multi-objective particle swarm. The problem has been reduced to a mathematical optimization problem by developing a fitness function considering losses and voltage distribution line. Fitness function by using the optimal value of the size and location of this algorithm was found to be minimized. IEEE-14 bus system is being considered, in order to test the proposed algorithm and the results show improved performance in terms of accuracy and convergence rate.

  12. Permanent alterations in muscarinic receptors and pupil size produced by chronic atropinization in kittens

    Energy Technology Data Exchange (ETDEWEB)

    Smith, E.L.; Redburn, D.A.; Harwerth, R.S.; Maguire, G.W.

    1984-02-01

    Chronic mydriasis was induced in six kittens (four monocular, two binocular) and two adult cats (both monocular) by the daily topical application of atropine. Both the kittens and the adult cats were atropinized for a 13-week period with the treatment regimen beginning at the time of eye opening for the kittens. Pupil size measurements, obtained 1 year after the atropinization were discontinued, revealed that, although the pupils of the adult cats were normal, the pupils of the kittens' treated eyes were consistently smaller than pupils in control eyes. The status of the muscarinic receptors in the kittens' irides was investigated using /sup 3/H-QNB binding assays. In comparison with iris muscle homogenates from the control eyes, those from the treated eyes demonstrated an eightfold increase in the number of receptor binding sites. The results indicate that pupil size can be altered permanently by chronic mydriasis initiated early in the life of a kitten and that the permanent change in pupil size may result, in part, from a type of permanent supersensitivity response in the muscle following chronic blockade of muscarinic transmission by atropine.

  13. Cryptic female choice: frogs reduce clutch size when amplexed by undesired males.

    Science.gov (United States)

    Reyer, H U; Frei, G; Som, C

    1999-10-22

    In species with internal fertilization, females can 'cryptically' choose (e.g. through sperm selection) which individuals sire their offspring, even when their overt preferences for copulatory partners are overrun by male-male competition and sexual coercion. The experiment presented here reveals that control of paternity after copulation has begun is also possible in species with external fertilization. Females of the hybridogenetic Rana essonae-Rana esculenta (LL-LR) waterfrog complex adjust their clutch size in response to mate type: they release fewer eggs when amplexed by hybrid LR males who--jeopardize successful reproduction--than when amplexed by parental LL males. This reduction in the number of eggs laid can increase a female's residual reproductive value through a second mating in the same breeding season or a larger clutch size in the next year. We argue that cryptic female choice through clutch size adjustment (i) may have evolved more often than previously assumed, and (ii) can arise even where females mate only once during a reproductive period.

  14. Sample Size Effect of Magnetomechanical Response for Magnetic Elastomers by Using Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Tsubasa Oguro

    2017-01-01

    Full Text Available The size effect of magnetomechanical response of chemically cross-linked disk shaped magnetic elastomers placed on a permanent magnet has been investigated by unidirectional compression tests. A cylindrical permanent magnet with a size of 35 mm in diameter and 15 mm in height was used to create the magnetic field. The magnetic field strength was approximately 420 mT at the center of the upper surface of the magnet. The diameter of the magnetoelastic polymer disks was varied from 14 mm to 35 mm, whereas the height was kept constant (5 mm in the undeformed state. We have studied the influence of the disk diameter on the stress-strain behavior of the magnetoelastic in the presence and in the lack of magnetic field. It was found that the smallest magnetic elastomer with 14 mm diameter did not exhibit measurable magnetomechanical response due to magnetic field. On the opposite, the magnetic elastomers with diameters larger than 30 mm contracted in the direction parallel to the mechanical stress and largely elongated in the perpendicular direction. An explanation is put forward to interpret this size-dependent behavior by taking into account the nonuniform field distribution of magnetic field produced by the permanent magnet.

  15. Design and Implementation of a Micron-Sized Electron Column Fabricated by Focused Ion Beam Milling

    CERN Document Server

    Wicki, Flavio; Escher, Conrad; Fink, Hans-Werner

    2015-01-01

    We have designed, fabricated and tested a micron-sized electron column with an overall length of about 700 microns comprising two electron lenses; a micro-lens with a minimal bore of 1 micron followed by a second lens with a bore of up to 50 microns in diameter to shape a coherent low-energy electron wave front. The design criteria follow the notion of scaling down source size, lens-dimensions and kinetic electron energy for minimizing spherical aberrations to ensure a parallel coherent electron wave front. All lens apertures have been milled employing a focused ion beam and could thus be precisely aligned within a tolerance of about 300 nm from the optical axis. Experimentally, the final column shapes a quasi-planar wave front with a minimal full divergence angle of 4 mrad and electron energies as low as 100 eV.

  16. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation

    KAUST Repository

    Carney, Randy P.

    2011-06-07

    Nanoparticles are finding many research and industrial applications, yet their characterization remains a challenge. Their cores are often polydisperse and coated by a stabilizing shell that varies in size and composition. No single technique can characterize both the size distribution and the nature of the shell. Advances in analytical ultracentrifugation allow for the extraction of the sedimentation (s) and diffusion coefficients (D). Here we report an approach to transform the s and D distributions of nanoparticles in solution into precise molecular weight (M), density (?P) and particle diameter (dp) distributions. M for mixtures of discrete nanocrystals is found within 4% of the known quantities. The accuracy and the density information we achieve on nanoparticles are unparalleled. A single experimental run is sufficient for full nanoparticle characterization, without the need for standards or other auxiliary measurements. We believe that our method is of general applicability and we discuss its limitations. 2011 Macmillan Publishers Limited. All rights reserved.

  17. Polarimetric Detection of Enantioselective Adsorption by Chiral Au Nanoparticles – Effects of Temperature, Wavelength and Size

    Directory of Open Access Journals (Sweden)

    Nisha Shukla

    2015-01-01

    Full Text Available R- and S-propylene oxide (PO have been shown to interact enantiospecifically with the chiral surfaces of Au nanopar‐ ticles (NPs modified with D- or L-cysteine (cys. This enantiospecific interaction has been detected using optical polarimetry measurements made on solutions of the D- or L-cys modified Au (cys/Au NPs during addition of racemic PO. The selective adsorption of one enantiomer of the PO onto the cys/Au NP surfaces results in a net rotation of light during addition of the racemic PO to the solution. In order to optimize the conditions used for making these measurements and to quantify enantiospecific adsorption onto chiral NPs, this work has measured the effect of temperature, wavelength and Au NP size on optical rotation by solutions containing D- or L-cys/Au NPs and racemic PO. Increasing temperature, decreasing wave‐ length and decreasing NP size result in larger optical rotations.

  18. Optimal receptor-cluster size determined by intrinsic and extrinsic noise

    CERN Document Server

    Aquino, Gerardo; Tollis, Sylvain; Endres, Robert G

    2011-01-01

    Biological cells sense external chemical stimuli in their environment using cell-surface receptors. To increase the sensitivity of sensing, receptors often cluster, most noticeably in bacterial chemotaxis, a paradigm for signaling and sensing in general. While amplification of weak stimuli is useful in absence of noise, its usefulness is less clear in presence of extrinsic input noise and intrinsic signaling noise. Here, exemplified on bacterial chemotaxis, we combine the allosteric Monod-Wyman- Changeux model for signal amplification by receptor complexes with calculations of noise to study their interconnectedness. Importantly, we calculate the signal-to-noise ratio, describing the balance of beneficial and detrimental effects of clustering for the cell. Interestingly, we find that there is no advantage for the cell to build receptor complexes for noisy input stimuli in absence of intrinsic signaling noise. However, with intrinsic noise, an optimal complex size arises in line with estimates of the sizes of ...

  19. Size-dependent nonlinear absorption and refraction of Ag nanoparticles excited by femtosecond lasers

    Institute of Scientific and Technical Information of China (English)

    Fan Guang-Hua; Qu Shi-Liang; Guo Zhong-Yi; Wang Qiang; Li Zhong-Guo

    2012-01-01

    Silver (Ag) nanoparticles with different average sizes are prepared,and the nonlinear absorption and refraction of these nanoparticles are investigated with femtosecond laser pulses at 800 nm.The smallest Ag nanoparticles show insignificant nonlinear absorption,whereas the larger ones show saturable absorption.By considering the previously reported positive nonlinear absorption of 9 nm Ag nanoparticles,the nonlinear absorptions of Ag nanoparticles are found to be size-dependent.All these nonlinear absorptions can be compatibly explained from the viewpoints of electronic transitions,energy bands and electronic structures in the conduction band of Ag nanoparticles.The nonlinear refraction is attributed to the effect of hot electrons arising from the intraband transition in the s-p conduction band of Ag nanoparticles.

  20. Photocatalytic self-cleaning properties of cellulosic fibers modified by nano-sized zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Moafi, Hadi Fallah; Shojaie, Abdollah Fallah, E-mail: a.f.shojaie@guilan.ac.ir; Zanjanchi, Mohammad Ali

    2011-03-31

    Nano-sized zinc oxide was synthesized and deposited onto cellulosic fibers using the sol-gel process at ambient temperature. The prepared materials were characterized using several techniques including scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction and thermogravimetric analysis. X-ray diffraction studies of the ZnO-coated fiber indicate formation of the hexagonal crystal phase which was satisfactory crystallized on the fiber surface. The electron micrographs show formation of zinc oxide nanoparticles within 10-15 nm in size which have been homogeneously dispersed on the fiber surface. The prepared materials show significant photocatalytic self-cleaning activity, which was monitored by diffuse reflectance spectroscopy. The photoactivity was studied upon measuring the photodegradation of methylene blue and eosin yellowish under UV-Vis irradiation. The photocatalytic activity of the treated fabrics was fully maintained performing several cycles of photodegradation.

  1. Crystalline capsules: metal-organic frameworks locked by size-matching ligand bolts.

    Science.gov (United States)

    Wang, Hao; Xu, Jian; Zhang, Da-Shuai; Chen, Qiang; Wen, Rong-Mei; Chang, Ze; Bu, Xian-He

    2015-05-11

    Metal-organic frameworks (MOFs) are shown to be good examples of a new class of crystalline porous materials for guest encapsulation. Since the encapsulation/release of guest molecules in MOF hosts is a reversible process in nature, how to prevent the leaching of guests from the open pores with minimal and nondestructive modifications of the structure is a critical issue. To address this issue, we herein propose a novel strategy of encapsulating guests by introducing size-matching organic ligands as bolts to lock the pores of the MOFs through deliberately anchoring onto the open metal sites in the pores. Our proposed strategy provides a mechanical way to prevent the leaching of guests and thereby has less dependence on the specific chemical environment of the hosts, thus making it applicable for a wide variety of existing MOFs once the size-matching ligands are employed.

  2. Attenuating the size and molecular carrier capabilities of polyacrylate nanoparticles by a hydrophobic fluorine effect.

    Science.gov (United States)

    Labruère, Raphaël; Turos, Edward

    2012-08-15

    This study investigates the effect of introducing alkyl chain fluorination on the properties of polyacrylate nanoparticles prepared in aqueous solution by emulsion polymerization. For this, 2,2,3,3,4,4,4-heptafluorobutyl acrylate (1) and methyl trifluoroacrylate (2) were tested as monomers as a means to prepare fluorinated polyacrylate nanoparticles to evaluate how side chain fluorination may affect nanoparticle size and drug carrier properties. Our results show that as fluorine content within the polyacrylate matrix increases, the size of the nanoparticle systematically diminishes, from 45 nm (for nanoparticles containing no fluoroacrylate) to ~7 nm (for nanoparticles constructed solely of fluoroacrylate). We also observe that as fluoroacrylate content and hydrophobicity increases, the nanoparticles decrease their ability to incorporate lipophilic molecules during the process of emulsification. These findings have meaningful implications in the implementation of fluorinated nanoparticles in molecular delivery.

  3. Integration of epigenetic and genetic controls of seed size by cytokinin in Arabidopsis.

    Science.gov (United States)

    Li, Jing; Nie, Xin; Tan, Jeanie Li Hui; Berger, Frédéric

    2013-09-17

    The development of seeds in flowering plants is placed under complex interactions between maternal tissues, the embryo, and the endosperm. The endosperm plays a major role in the regulation of seed size. In Arabidopsis thaliana, endosperm size depends on the coordination of the genetic pathway HAIKU (IKU) with epigenetic controls comprising genome dosage, DNA methylation, and trimethylated lysine 27 on histone H3 (H3K27me3) deposition. However, the effectors that integrate these pathways have remained unknown. Here, we identify a target of the IKU pathway, the cytokinin oxidase CKX2, that affects cytokinin signaling. CKX2 expression is activated by the IKU transcription factor WRKY10 directly and promotes endosperm growth. CKX2 expression also depends on H3K27me3 deposition, which fluctuates in response to maternal genome dosage imbalance and DNA demethylation of male gametes. Hence, the control of endosperm growth by CKX2 integrates genetic and epigenetic regulations. In angiosperms, cytokinins are highly active in endosperm, and we propose that IKU effectors coordinate environmental and physiological factors, resulting in modulation of seed size.

  4. Liposomes Size Engineering by Combination of Ethanol Injection and Supercritical Processing.

    Science.gov (United States)

    Santo, Islane Espirito; Campardelli, Roberta; Albuquerque, Elaine Cabral; Vieira De Melo, Silvio A B; Reverchon, Ernesto; Della Porta, Giovanna

    2015-11-01

    Supercritical fluid extraction using a high-pressure packed tower is proposed not only to remove the ethanol residue from liposome suspensions but also to affect their size and distribution leading the production of nanosomes. Different operating pressures, temperatures, and gas to liquid ratios were explored and ethanol was successfully extracted up to a value of 400 ppm; liposome size and distribution were also reduced by the supercritical processing preserving their integrity, as confirmed by Z-potential data and Trasmission Electron Microscopy observations. Operating at 120 bar and 38°C, nanosomes with a mean diameter of about 180 ± 40 nm and good storage stability were obtained. The supercritical processing did not interfere on drug encapsulation, and no loss of entrapped drug was observed when the water-soluble fluorescein was loaded as a model compound. Fluorescein encapsulation efficiency was 30% if pure water was used during the supercritical extraction as processing fluid; whereas an encapsulation efficiency of 90% was obtained if the liposome suspension was processed in water/fluorescein solution. The described technology is easy to scale up to an industrial production and merge in one step the solvent extraction, liposome size engineering, and an excellent drug encapsulation in a single operation unit.

  5. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives.

    Science.gov (United States)

    Contado, Catia; Ravani, Laura; Passarella, Martina

    2013-07-25

    Four types of SiO2, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w(-1)) a nearly silica-free instant barley coffee powder with a known SiO2 sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO2 particles and verify the new particle size distribution. The SiO2 content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w(-1)). The protocol to isolate the silica particles was so applied to the most SiO2-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification.

  6. Selection of MOSFET Sizes by Fuzzy Sets Intersection in the Feasible Solutions Space

    Directory of Open Access Journals (Sweden)

    S. Polanco-Martagón

    2012-06-01

    Full Text Available A fuzzy sets intersection procedure to select the optimum sizes of analog circuits composed of metal-oxidesemiconductorfield-effect-transistors (MOSFETs, is presented. The cases of study are voltage followers (VFs and acurrent-feedback operational amplifier (CFOA, where the width (W and length (L of the MOSFETs are selected fromthe space of feasible solutions computed by swarm or evolutionary algorithms. The evaluation of three objectives,namely: gain, bandwidth and power consumption; is performed using HSPICETM with standard integrated circuit (ICtechnology of 0.35μm for the VFs and 180nm for the CFOA. Therefore, the intersection procedure among three fuzzysets representing “gain close to unity”, ”high bandwidth” and “minimum power consumption”, is presented. The mainadvantage relies on its usefulness to select feasible W/L sizes automatically but by considering deviation percentagesfrom the desired target specifications. Basically, assigning a threshold to each fuzzy set does it. As a result, theproposed approach selects the best feasible sizes solutions to guarantee and to enhance the performances of the ICsin analog signal processing applications.

  7. OPTIMIZATION OF COMMINUTION CIRCUIT THROUGHPUT AND PRODUCT SIZE DISTRIBUTION BY SIMULATION AND CONTROL

    Energy Technology Data Exchange (ETDEWEB)

    T.C. Eisele; S.K. Kawatra; H.J. Walqui

    2004-10-01

    The goal of this project is to improve energy efficiency of industrial crushing and grinding operations (comminution). Mathematical models of the comminution process are being used to study methods for optimizing the product size distribution, so that the amount of excessively fine material produced can be minimized. The goal is to save energy by reducing the amount of material that is ground below the target size, while simultaneously reducing the quantity of materials wasted as ''slimes'' that are too fine to be useful. This is being accomplished by mathematical modeling of the grinding circuits to determine how to correct this problem. The approaches taken included (1) Modeling of the circuit to determine process bottlenecks that restrict flowrates in one area while forcing other parts of the circuit to overgrind the material; (2) Modeling of hydrocyclones to determine the mechanisms responsible for retaining fine, high-density particles in the circuit until they are overground, and improving existing models to accurately account for this behavior; and (3) Evaluation of advanced technologies to improve comminution efficiency and produce sharper product size distributions with less overgrinding.

  8. Gaseous and particulate composition of fresh and aged emissions of diesel, RME and CNG buses using Chemical Ionization Mass Spectrometry

    Science.gov (United States)

    Psichoudaki, Magda; Le Breton, Michael; Hallquist, Mattias; Watne, Ågot; Hallquist, Asa

    2016-04-01

    Urban air pollution is becoming a significant global problem, especially for large cities around the world. Traffic emissions contribute significantly to both elevated particle concentrations and to gaseous pollutants in cities. The latter also have the potential of forming more particulate mass via their photochemical oxidation in the atmosphere. The International Agency for Research on Cancer and the US EPA have characterised diesel exhausts as a likely human carcinogen that can also contribute to other health problems. In order to meet the challenges with increased transportation and enhanced greenhouse gas emissions, the European Union have decided on a 10% substitution of traditional fuels in the road transport sector by alternative fuels (e.g. biodiesel, CNG) before the year 2020. However, it is also important to study the influence of fuel switches on other primary pollutants as well as the potential to form secondary aerosol mass. This work focuses on the characterisation of the chemical composition of the gas and the condensed phase of fresh bus emissions during acceleration, in order to mimic the exhaust plume that humans would inhale under realistic conditions. In addition, photochemical aging of the exhaust emissions was achieved by employing a Potential Aerosol Mass (PAM) flow reactor, allowing the characterization of the composition of the corresponding aged emissions. The PAM reactor uses UV lamps and high concentrations of oxidants (OH radicals and O3) to oxidize the organic species present in the chamber. The oxidation that takes place within the reactor can be equivalent to up to one week of atmospheric oxidation. Preliminary tests showed that the oxidation employed in these measurements corresponded to a range from 4 to 8 days in the atmosphere. During June and July 2015, a total of 29 buses, 5 diesel, 13 CNG and 11 RME (rapeseed methyl ester), were tested in two different locations with limited influence from other types of emissions and traffic

  9. Layer-by-Layer Assembly Onto Gold Nanoparticles of Various Size

    Science.gov (United States)

    Kilroy, Andrew; Kessler, Sarah; Dobbins, Tabbetha

    This research focuses on the potential applications of coated gold nanoparticles in medicine. By coating gold nanoparticles in layers of polyelectrolytes, with a final layer of antibodies which targets chemicals uniquely exhibited by cancer cells, we eventually hope to selectively attach the nanoparticles to the cancer cells. The coated nanoparticles are assembled through layer-by-layer coulombic attraction due to the passive zeta potential of the particle and the charged nature of the polyelectrolytes. This poster will explore the potential usefulness of variously sized nanoparticles with various thickness of polyelectrolyte layers.

  10. The quantification of spermatozoa by real-time quantitative PCR, spectrophotometry, and spermatophore cap size.

    Science.gov (United States)

    Doyle, Jacqueline M; McCormick, Cory R; DeWoody, J Andrew

    2011-01-01

    Many animals, such as crustaceans, insects, and salamanders, package their sperm into spermatophores, and the number of spermatozoa contained in a spermatophore is relevant to studies of sexual selection and sperm competition. We used two molecular methods, real-time quantitative polymerase chain reaction (RT-qPCR) and spectrophotometry, to estimate sperm numbers from spermatophores. First, we designed gene-specific primers that produced a single amplicon in four species of ambystomatid salamanders. A standard curve generated from cloned amplicons revealed a strong positive relationship between template DNA quantity and cycle threshold, suggesting that RT-qPCR could be used to quantify sperm in a given sample. We then extracted DNA from multiple Ambystoma maculatum spermatophores, performed RT-qPCR on each sample, and estimated template copy numbers (i.e. sperm number) using the standard curve. Second, we used spectrophotometry to determine the number of sperm per spermatophore by measuring DNA concentration relative to the genome size. We documented a significant positive relationship between the estimates of sperm number based on RT-qPCR and those based on spectrophotometry. When these molecular estimates were compared to spermatophore cap size, which in principle could predict the number of sperm contained in the spermatophore, we also found a significant positive relationship between sperm number and spermatophore cap size. This linear model allows estimates of sperm number strictly from cap size, an approach which could greatly simplify the estimation of sperm number in future studies. These methods may help explain variation in fertilization success where sperm competition is mediated by sperm quantity.

  11. Improving Sunflower Halva Stability and Texture by Controlling Tahini Particle Size Distribution

    Directory of Open Access Journals (Sweden)

    Vlad Mureşan

    2015-05-01

    Full Text Available Sunflower halva is an appreciated product, but shows currently a quality below the expectations of the new generation of consumers, having a hard texture and oil exuded on the surface (low stability. The aim of this work was to assess the influence of tahini particle size on sunflower halva texture and stability. Eight different particle size sunflower tahini samples were produced at pilot plant scale, the higher the number of passes through the colloidal mill, the smaller the particle size (P1- coarsest → P8 - finest. Halva prototypes (25g / piece, including also an industrial sample (H0, were obtained at laboratory scale by mixing the nougat with tahini. The texture was evaluated on Stable micro systems TA.HD Plus texture analyzer equipped either with a cylinder probe or with a blade set. All samples were stored for 60 days at 4°C, room temperature (~25°C or 40°C. During storage, the colloidal stability of all samples was assessed by a gravimetric technique. Tahini samples P6 → P8 were not suitable for halva production while due to the low viscosities, the product was impossible to be shaped. Among obtained sunflower halva prototypes (H1 → H5 it was shown that decreasing tahini particle size decreased sunflower halva hardness and stability. For each sample, the increase of storage temperature decreased sunflower halva stability. Sunflower halva H3 was the most efficient, while was more stable and showed smaller hardness values than H0.

  12. Intra- and trans-generational costs of reduced female body size caused by food limitation early in life in mites.

    Directory of Open Access Journals (Sweden)

    Andreas Walzer

    Full Text Available Food limitation early in life may be compensated for by developmental plasticity resulting in accelerated development enhancing survival at the expense of small adult body size. However and especially for females in non-matching maternal and offspring environments, being smaller than the standard may incur considerable intra- and trans-generational costs.Here, we evaluated the costs of small female body size induced by food limitation early in life in the sexually size-dimorphic predatory mite Phytoseiulus persimilis. Females are larger than males. These predators are adapted to exploit ephemeral spider mite prey patches. The intra- and trans-generational effects of small maternal body size manifested in lower maternal survival probabilities, decreased attractiveness for males, and a reduced number and size of eggs compared to standard-sized females. The trans-generational effects of small maternal body size were sex-specific with small mothers producing small daughters but standard-sized sons.Small female body size apparently intensified the well-known costs of sexual activity because mortality of small but not standard-sized females mainly occurred shortly after mating. The disadvantages of small females in mating and egg production may be generally explained by size-associated morphological and physiological constraints. Additionally, size-assortative mate preferences of standard-sized mates may have rendered small females disproportionally unattractive mating partners. We argue that the sex-specific trans-generational effects were due to sexual size dimorphism - females are the larger sex and thus more strongly affected by maternal stress than the smaller males - and to sexually selected lower plasticity of male body size.

  13. Improved Light Conversion Efficiency Of Dye-Sensitized Solar Cell By Dispersing Submicron-Sized Granules Into The Nano-Sized TiO2 Layer

    Directory of Open Access Journals (Sweden)

    Song S.A.

    2015-06-01

    Full Text Available In this work, TiO2 nanoparticles and submicron-sized granules were synthesized by a hydrothermal method and spray pyrolysis, respectively. Submicron-sized granules were dispersed into the nano-sized TiO2 layer to improve the light conversion efficiency. Granules showed better light scattering, but lower in terms of the dye-loading quantity and recombination resistance compared with nanoparticles. Consequently, the nano-sized TiO2 layer had higher cell efficiency than the granulized TiO2 layer. When dispersed granules into the nanoparticle layer, the light scattering was enhanced without the loss of dye-loading quantities. The dispersion of granulized TiO2 led to increase the cell efficiency up to 6.51%, which was about 5.2 % higher than that of the electrode consisting of only TiO2 nanoparticles. Finally, the optimal hydrothermal temperature and dispersing quantity of granules were found to be 200°C and 20 wt%, respectively.

  14. BINDER DRAINAGE TEST FOR POROUS MIXTURES MADE BY VARYING THE MAXIMUM AGGREGATE SIZES

    Directory of Open Access Journals (Sweden)

    Hardiman Hardiman

    2004-01-01

    Full Text Available Binder drainage occurs with mixes of small aggregate surface area particularly porous asphalt. The binder drainage test, developed by the Transport Research Laboratory, UK, is commonly used to set an upper limit on the acceptable binder content for a porous mix. This paper presents the results of a laboratory investigation to determine the effects of different binder types on the binder drainage characteristics of porous mix made of various maximum aggregate sizes 20, 14 and 10 mm. Two types of binder were used, conventional 60/70 pen bitumen, and styrene butadiene styrene (SBS modified bitumen. The amount of binder lost through drainage after three hours at the maximum mixing temperature were measured in duplicate for mixes of different maximum sizes and binder contents. The maximum mixing temperature adopted depends on the types of binder used. The retained binder is plotted against the initial mixed binder content, together with the line of equality where the retained binder equals the mixed binder content. The results indicate the significant contribution of using SBS modified bitumen to increase the target bitumen binder content. Their significance is discussed in terms of target binder content, the critical binder content, the maximum mixed binder content and the maximum retained binder content values obtained from the binder drainage test. It was concluded that increasing maximum aggregate sizes decrease the maximum retained binder content, critical binder content, target binder content, maximum mixed binder content, and mixed content for both binders, but however for all mixtures, SBS is the highest.

  15. Nano sized bismuth oxy chloride by metal organic chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Jagdale, Pravin, E-mail: pravin.jagdale@polito.it [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy); Castellino, Micaela [Center for Space Human Robotics, Istituto Italiano di Tecnologia, Corso Trento 21, 10129 Torino (Italy); Marrec, Françoise [Laboratory of Condensed Matter Physics, University of Picardie Jules Verne (UPJV), Amiens 80039 (France); Rodil, Sandra E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexicom (UNAM), Mexico D.F. 04510 (Mexico); Tagliaferro, Alberto [Department of Applied Science and Technology (DISAT), Politecnico di Torino, 10129 (Italy)

    2014-06-01

    Metal organic chemical vapour deposition (MOCVD) method was used to prepare thin films of bismuth based nano particles starting from bismuth salts. Nano sized bismuth oxy chloride (BiOCl) crystals were synthesized from solution containing bismuth chloride (BiCl{sub 3}) in acetone (CH{sub 3}-CO-CH{sub 3}). Self-assembly of nano sized BiOCl crystals were observed on the surface of silicon, fused silica, copper, carbon nanotubes and aluminium substrates. Various synthesis parameters and their significant impact onto the formation of self-assembled nano-crystalline BiOCl were investigated. BiOCl nano particles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy and Micro-Raman spectroscopy. These analyses confirm that bismuth nanometer-sized crystal structures showing a single tetragonal phase were indeed bismuth oxy chloride (BiOCl) square platelets 18–250 nm thick and a few micrometres wide.

  16. Indentation Size Effects in Single Crystal Copper as Revealed by Synchrotron X-ray Microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Feng, G.; Budiman, A. S.; Nix, W. D.; Tamura, N.; Patel, J. R.

    2007-11-19

    The indentation size effect (ISE) has been observed in numerous nanoindentation studies on crystalline materials; it is found that the hardness increases dramatically with decreasing indentation size - a 'smaller is stronger' phenomenon. Some have attributed the ISE to the existence of strain gradients and the geometrically necessary dislocations (GNDs). Since the GND density is directly related to the local lattice curvature, the Scanning X-ray Microdiffraction ({mu}SXRD) technique, which can quantitatively measure relative lattice rotations through the streaking of Laue diffractions, can used to study the strain gradients. The synchrotron {mu}SXRD technique we use - which was developed at the Advanced Light Source (ALS), Berkeley Lab - allows for probing the local plastic behavior of crystals with sub-micrometer resolution. Using this technique, we studied the local plasticity for indentations of different depths in a Cu single crystal. Broadening of Laue diffractions (streaking) was observed, showing local crystal lattice rotation due to the indentation-induced plastic deformation. A quantitative analysis of the streaking allows us to estimate the average GND density in the indentation plastic zones. The size dependence of the hardness, as found by nanoindentation, will be described, and its correlation to the observed lattice rotations will be discussed.

  17. Particle Size-Dependent Antibacterial Activity and Murine Cell Cytotoxicity Induced by Graphene Oxide Nanomaterials

    Directory of Open Access Journals (Sweden)

    Lin Zhao

    2016-01-01

    Full Text Available Recent studies have indicated that graphene and its derivative graphene oxide (GO engage in a wide range of antibacterial activities with limited toxicity to human cells. Here, we systematically evaluate the dependence of GO toxicity on the size of the nanoparticles used in treatments: we compare the cytotoxic effects of graphene quantum dots (GQDs, <15 nm, small GOs (SGOs, 50–200 nm, and large GOs (LGOs, 0.5–3 μm. We synthesize the results of bacterial colony count assays and SEM-based observations of morphological changes to assess the antibacterial properties that these GOs bring into effect against E. coli. We also use Live/Dead assays and morphological analysis to investigate changes to mammalian (Murine macrophage-like Raw 264.7 cells induced by the presence of the various GO particle types. Our results demonstrate that LGOs, SGOs, and GQDs possess antibacterial activities and cause mammalian cell cytotoxicity at descending levels of potency. Placing our observations in the context of previous simulation results, we suggest that both the lateral size and surface area of GO particles contribute to cytotoxic effects. We hope that the size dependence elucidated here provides a useful schematic for tuning GO-cell interactions in biomedical applications.

  18. THE RELATIONSHIP BETWEEN ORGANISATIONAL COMPETITIVE ADVANTAGE AND PERFORMANCE MODERATED BY THE AGE AND SIZE OF FIRMS

    Directory of Open Access Journals (Sweden)

    Alimin Ismadi Ismail

    2010-07-01

    Full Text Available It has been argued that achieving a position of competitive advantage is a necessary precursor to a firm's significant performance. This paper will empirically examine the potential moderating variables that could affect the relationship between a firm's competitive advantage and performance, namely the firms' age and size. By examining the relative moderating effects of these variables, this paper delivers valuable information to firms, specifically with regard to strategic management directed toward performance and attaining a competitive advantage. This research was conducted among 127 manufacturers listed in the 2008 Federation of Malaysian Manufacturers Directory. A cross- sectional study was conducted using a structured questionnaire to obtain responses from the manufacturers. A two-way ANOVA shows that only the age of firms is a significant moderator in the relationship between competitive advantage and performance, and that this relationship is stronger for older firms. The size of firms does not significantly moderate the relationship between competitive advantage and performance. Despite the non-significant moderating effect of firms' size, overall, this study provides empirical support for the Resource-Based View (RBV of Malaysian manufacturers regarding the issue of competitive advantage.

  19. Habitat-specific size structure variations in periwinkle populations ( Littorina littorea) caused by biotic factors

    Science.gov (United States)

    Eschweiler, Nina; Molis, Markus; Buschbaum, Christian

    2009-06-01

    Shell size distribution patterns of marine gastropod populations may vary considerably across different environments. We investigated the size and density structure of genetically continuous periwinkle populations ( Littorina littorea) on an exposed rocky and a sheltered sedimentary environment on two nearby islands in the south-eastern North Sea (German Bight). On the sedimentary shore, periwinkle density (917 ± 722 individuals m-2) was about three times higher than on the rocky shore (296 ± 168 individuals m-2). Mean (9.8 ± 3.9 mm) and maximum (22 mm) shell size of L. littorea on the sedimentary shore were smaller than on the rocky shore (21.5 ± 4.2 and 32 mm, respectively), where only few small snails were found. Additionally, periwinkle shells were thicker and stronger on the rocky than on the sedimentary shore. To ascertain mechanisms responsible for differences in population structures, we examined periwinkles in both environments for growth rate, predation pressure, infection with a shell boring polychaete ( Polydora ciliata) and parasitic infestation by trematodes. A crosswise transplantation experiment revealed better growth conditions on the sedimentary than on the rocky shore. However, crab abundance and prevalence of parasites and P. ciliata in adult snails were higher on the sedimentary shore. Previous investigations showed that crabs prefer large periwinkles infested with P. ciliata. Thus, we suggest that parasites and shell boring P. ciliata in conjunction with an increased crab predation pressure are responsible for low abundances of large periwinkles on the sedimentary shore while high wave exposure may explain low densities of juvenile L. littorea on the rocky shore. We conclude that biotic factors may strongly contribute to observed differences in size structure of the L. littorea populations studied on rocky and sedimentary shores.

  20. Amino acid substitution at the Adh locus of Drosophila is facilitated by small population size.

    Science.gov (United States)

    Ohta, T

    1993-01-01

    The number of amino acid replacement substitutions and that of synonymous substitutions are examined by using DNA sequences of the Adh locus of Drosophila. The ratio of replacement to synonymous substitutions is higher in sequence comparisons between species than in polymorphisms within species. The ratio for the between-species comparisons is highest in the Hawaiian group and lowest in the obscura group. These observations suggest that amino acid substitutions are facilitated by small population size. The result is in accord with the nearly neutral theory of molecular evolution. PMID:8506297

  1. Tuning the Properties of Polymer Bulk Heterojunction Solar Cells by Adjusting Fullerene Size to Control Intercalation

    KAUST Repository

    Cates, Nichole C.

    2009-12-09

    We demonstrate that intercalation of fullerene derivatives between the side chains of conjugated polymers can be controlled by adjusting the fullerene size and compare the properties of intercalated and nonintercalated poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (pBTTT):fullerene blends. The intercalated blends, which exhibit optimal solar-cell performance at 1:4 polymer:fullerene by weight, have better photoluminescence quenching and lower absorption than the nonintercalated blends, which optimize at 1:1. Understanding how intercalation affects performance will enable more effective design of polymer:fullerene solar cells. © 2009 American Chemical Society.

  2. Quantum size effects in TiO2 thin films grown by atomic layer deposition.

    Science.gov (United States)

    Tallarida, Massimo; Das, Chittaranjan; Schmeisser, Dieter

    2014-01-01

    We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier transport and separation, and increase the efficiency of energy conversion systems.

  3. Quantum size effects in TiO2 thin films grown by atomic layer deposition

    OpenAIRE

    Tallarida, Massimo; Das, Chittaranjan; Schmeisser, Dieter

    2014-01-01

    We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier...

  4. Mie scattering by ensembles of particles with very large size parameters

    Science.gov (United States)

    Wolf, S.; Voshchinnikov, N. V.

    2004-09-01

    wavelength range (λ~10-10-10-2m) of the interacting radiation are considered. Previous numerical solutions to the Mie scattering problem are not appropriate to consider size parameters x=2πa/λ>104-105. In contrast to this, the presented code allows to consider arbitrary size parameters. It will be useful not only for applications in astrophysics but also in other fields of science (atmospheric and ocean optics, biophysics, etc.) and industry (particle sizing, ecology control measurements, etc.). Method of solution: Calculations of Mie scattering coefficients and efficiency factors as outlined by Voshchinnikov (2004), combined with standard solutions of the scattering amplitude functions. Single scattering by particle ensembles is calculated by proper averaging of the respective parameters. Restrictions on the complexity of the problem: Single scattering Typical running time: Seconds to minutes Unusual features of the program: None References: C.F. Bohren, D.R. Huffman, Absorption and Scattering of Light by Small Particles, John Wiley & Sons, New York, 1983. N.V. Voshchinnikov, Optics of cosmic dust. I, Astrophys. and Space Phys. Rev. 12 (2004) 1.

  5. Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique

    Indian Academy of Sciences (India)

    Wen Yan; Nan Li; Yuanyuan Li; Guangping Liu; Bingqiang Han; Juliang Xu

    2011-08-01

    The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on microstructure and strength were investigated. It was found that particle size affects strongly on the microstructure and strength. With decreasing particle size, the pore size distribution occurs from multi-peak mode to bi-peak mode, and lastly to mono-peak mode; the porosity decreases but strength increases. The most apposite mode is the specimens from the grinded powder with a particle size of 6.53 m, which has a high apparent porosity (40%), a high compressive strength (75.6MPa), a small average pore size (2.53 m) and a homogeneous pore size distribution.

  6. Exact equations for soil particle-size analysis by gamma-ray attenuation

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Elimoel Abraao; Bacchi, Osny Oliveira Santos; Reichardt, Klaus [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab, de Fisica do Solo

    1999-03-01

    Soil particle-size analysis by gamma-ray attenuation was first suggested in 1992 and improved in 1997 by diminishing the measurement time and adapting it for automation. It is here demonstrated that when the mass attenuation coefficient {mu}{sub w} and the density D{sub w} are replaced by {mu}{sub s} and D{sub s} (where the subscripts w and s stand for water and solution) in the approximate equations used to estimate the concentration of suspended particles, they become exact. The demonstration is based by treating the dispersant and water solution as one single medium, instead of treating them as two media In this way, six variables are reduced to only three. Physical considerations suggest that the precision in this analysis could be improved if other types of solutions and of photon energies would be used, so that the attenuation by the particles would differ more significantly from the attenuation by the solution. (author)

  7. The evolution of relative brain size in marsupials is energetically constrained but not driven by behavioral complexity.

    Science.gov (United States)

    Weisbecker, Vera; Blomberg, Simon; Goldizen, Anne W; Brown, Meredeth; Fisher, Diana

    2015-01-01

    Evolutionary increases in mammalian brain size relative to body size are energetically costly but are also thought to confer selective advantages by permitting the evolution of cognitively complex behaviors. However, many suggested associations between brain size and specific behaviors - particularly related to social complexity - are possibly confounded by the reproductive diversity of placental mammals, whose brain size evolution is the most frequently studied. Based on a phylogenetic generalized least squares analysis of a data set on the reproductively homogenous clade of marsupials, we provide the first quantitative comparison of two hypotheses based on energetic constraints (maternal investment and seasonality) with two hypotheses that posit behavioral selection on relative brain size (social complexity and environmental interactions). We show that the two behavioral hypotheses have far less support than the constraint hypotheses. The only unambiguous associates of brain size are the constraint variables of litter size and seasonality. We also found no association between brain size and specific behavioral complexity categories within kangaroos, dasyurids, and possums. The largest-brained marsupials after phylogenetic correction are from low-seasonality New Guinea, supporting the notion that low seasonality represents greater nutrition safety for brain maintenance. Alternatively, low seasonality might improve the maternal support of offspring brain growth. The lack of behavioral brain size associates, found here and elsewhere, supports the general 'cognitive buffer hypothesis' as the best explanatory framework of mammalian brain size evolution. However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.

  8. [Effectiveness of arsenite adsorption by ferric and alum water treatment residuals with different grain sizes].

    Science.gov (United States)

    Lin, Lu; Xu, Jia-Rui; Wu, Hao; Wang, Chang-Hui; Pei, Yuan-Sheng

    2013-07-01

    Effectiveness of arsenite adsorption by ferric and alum water treatment residuals (FARs) with different grain sizes was studied. The results indicated that the content of active Fe and Al, the specific surface area and pore volume in FARs with different grain sizes were in the range of 523.72-1 861.72 mmol x kg(-1), 28.15-265.59 m2 x g(-1) and 0.03-0.09 cm3 x g(-1), respectively. The contents of organic matter, fulvic acid, humic acid and humin were in the range of 46.97-91.58 mg x kg(-1), 0.02-32.27 mg x kg(-1), 22.27-34.09 mg x kg(-1) and 10.76-34.22 mg x kg(-1), respectively. Results of SEM and XRD analysis further demonstrated that FARs with different grain sizes were amorphousness. Batch experiments suggested that both the pseudo-first-order and pseudo-second-order equations could well describe the kinetics adsorption processes of arsenite by FARs. Moreover, the contents of arsenite absorbed by FARs increased with the increase of arsenite concentrations. The theoretical saturated adsorption capacities calculated from Langmuir isotherm model were in the range of 6.72-21.79 mg x g(-1). Interestingly, pH showed little effect on the arsenite adsorption capability of FARs. The capability of FARs had a close relationship with their physicochemical properties. Correlation analysis showed that the active Fe and Al contents and pore volume had major effects on the arsenite adsorption capability of FARs.

  9. Control of pore size and structure of tissue engineering scaffolds produced by supercritical fluid processing

    Directory of Open Access Journals (Sweden)

    H Tai

    2007-12-01

    Full Text Available Tissue engineering scaffolds require a controlled pore size and structure to host tissue formation. Supercritical carbon dioxide (scCO2 processing may be used to form foamed scaffolds in which the escape of CO2 from a plasticized polymer melt generates gas bubbles that shape the developing pores. The process of forming these scaffolds involves a simultaneous change in phase in the CO2 and the polymer, resulting in rapid expansion of a surface area and changes in polymer rheological properties. Hence, the process is difficult to control with respect to the desired final pore size and structure. In this paper, we describe a detailed study of the effect of polymer chemical composition, molecular weight and processing parameters on final scaffold characteristics. The study focuses on poly(DL-lactic acid (PDLLA and poly(DL-lactic acid-co-glycolic acid (PLGA as polymer classes with potential application as controlled release scaffolds for growth factor delivery. Processing parameters under investigation were temperature (from 5 to 55oC and pressure (from 60 to 230 bar. A series of amorphous PDLLA and PLGA polymers with various molecular weights (from 13 KD to 96 KD and/or chemical compositions (the mole percentage of glycolic acid in the polymers was 0, 15, 25, 35 and 50 respectively were employed. The resulting scaffolds were characterised by optical microscopy, scanning electron microscopy (SEM, and micro X-ray computed tomography (µCT. This is the first detailed study on using these series polymers for scaffold formation by supercritical technique. This study has demonstrated that the pore size and structure of the supercritical PDLLA and PLGA scaffolds can be tailored by careful control of processing conditions.

  10. Adenovirus purification by two-column, size-exclusion, simulated countercurrent chromatography.

    Science.gov (United States)

    Nestola, Piergiuseppe; Silva, Ricardo J S; Peixoto, Cristina; Alves, Paula M; Carrondo, Manuel J T; Mota, José P B

    2014-06-20

    Adenovirus serotype 5 (Ad5) was successfully separated by size-exclusion chromatography (SEC) using a simple, yet efficient, two-column, quasi-continuous, simulated moving-bed process operated in an open-loop configuration. The operating cycle is divided into two identical half-cycles, each of them consisting of the following sequence of sub-steps: (i) elution of the upstream column and direction of the effluent of the downstream column to waste; (ii) elution of the upstream column and redirection of its effluent to waste while the downstream column is fed with the clarified bioreaction bulk and its effluent collected as purified product; (iii) operation of the system as in step (i) but collecting the effluent of the downstream column as product; (iv) elution of the upstream column and direction of its effluent to waste while the flow through the downstream column is temporarily halted. Clearance of impurities, namely DNA and host cell protein (HCP), were experimentally assessed. The pilot-scale run yielded a virus recovery of 86%, and a clearance of 90% and 89% for DNA and HCP, respectively, without any fine tunning of the predetermined operating parameters. These figures compare very favorably against single-column batch chromatography for the same volume of size-exclusion resin. However, and most importantly, the virus yield was increased from 57% for the batch system to 86% for the two-column SEC process because of internal recycling of the mixed fractions of contaminated Ad5, even though the two-column process was operated strictly in an open-loop configuration. And last, but not least, the productivity was increased by 6-fold with the two-column process. In conclusion, the main drawbacks of size-exclusion chromatography, namely low productivity and low product titer, were overcome to a considerable extent by an innovative two-column configuration that keeps the mixed fractions inside the system at all times.

  11. Beam Size Measurement by Optical Diffraction Radiation and Laser System for Compton Polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chuyu [Peking Univ., Beijing (China)

    2012-12-31

    Beam diagnostics is an essential constituent of any accelerator, so that it is named as "organs of sense" or "eyes of the accelerator." Beam diagnostics is a rich field. A great variety of physical effects or physical principles are made use of in this field. Some devices are based on electro-magnetic influence by moving charges, such as faraday cups, beam transformers, pick-ups; Some are related to Coulomb interaction of charged particles with matter, such as scintillators, viewing screens, ionization chambers; Nuclear or elementary particle physics interactions happen in some other devices, like beam loss monitors, polarimeters, luminosity monitors; Some measure photons emitted by moving charges, such as transition radiation, synchrotron radiation monitors and diffraction radiation-which is the topic of the first part of this thesis; Also, some make use of interaction of particles with photons, such as laser wire and Compton polarimeters-which is the second part of my thesis. Diagnostics let us perceive what properties a beam has and how it behaves in a machine, give us guideline for commissioning, controlling the machine and indispensable parameters vital to physics experiments. In the next two decades, the research highlight will be colliders (TESLA, CLIC, JLC) and fourth-generation light sources (TESLA FEL, LCLS, Spring 8 FEL) based on linear accelerator. These machines require a new generation of accelerator with smaller beam, better stability and greater efficiency. Compared with those existing linear accelerators, the performance of next generation linear accelerator will be doubled in all aspects, such as 10 times smaller horizontal beam size, more than 10 times smaller vertical beam size and a few or more times higher peak power. Furthermore, some special positions in the accelerator have even more stringent requirements, such as the interaction point of colliders and wigglor of free electron lasers. Higher performance of these accelerators increases the

  12. Huge nanodielectric effects in polyimide/boron nitride nanocomposites revealed by the nanofiller size

    Science.gov (United States)

    Diaham, S.; Saysouk, F.; Locatelli, M.-L.; Lebey, T.

    2015-09-01

    The dielectric properties of polyimide/boron nitride (PI/BN) nanocomposite films are investigated as a function of the BN nanofiller size from 20 to 350 °C and at low filler content (1-2 vol.%). The role of the BN nanofiller size on the large reduction of the electrode polarization relaxation phenomenon due to ionic movements is reported. For the two smallest BN nanoparticles (95 nm and 35 nm), the permittivity, dielectric losses and dc conductivity are strongly attenuated above 200 °C by a factor of 10 to 1000 compared to neat PI. Thus, the dc conductivity at 350 °C is reduced from 4   ×   10-8 Ω-1 cm-1 for neat PI to 3   ×   10-11 Ω-1 cm-1 for PI/BN (35 nm). Moreover, a further decrease is obtained by functionalizing the nanofiller surface with a silane coupling agent which improves the grafting of PI chains on those latter nanoparticles. These results highlight the trapping efficiency in the interphase region introduced by the small BN nanofillers (<100 nm) and provides evidence as to the huge nanodielectric effects on the charge carrier transport controlled by the nanoparticle diameter. This finding should be of great importance for advanced high temperature electrical insulation in the future.

  13. Large 2D-arrays of size-controllable silver nanoparticles prepared by hybrid deposition

    Science.gov (United States)

    Dieu Thuy Ung, Thi; Hoa Nguyen, Thi; Liem Nguyen, Quang

    2016-09-01

    Two main results are presented in this paper. (i) Silver nanoparticles (AgNPs) with uniform size-distribution and controllability in the range of 20-50 nm were synthesized by seeding and growing at ambient conditions. The single-crystal Ag nano-seeds were created by reduction of AgNO3 in presence of citrate surfactant at 70 °C. Then, importantly, the fresh AgCl precursor was used in the presence of polyvinylpyrrolidone to adjust the reaction rate with ascorbic acid to generate Ag for growing on the surface of single-crystal Ag nano-seeds. The AgNPs size could be well-controlled by varying the amount of Ag nano-seeds while keeping the AgCl precursor concentration to be constant. (ii) The large 2D-arrays with homogeneous and dense monolayers of AgNPs were prepared on ITO substrates by hybrid method, in which the key technological point is the surface functionalization of AgNPs using mixed alkanethiols (dodecanethiol:octadecanethiol = 6:1). We have used the fabricated 2D-arrays from the 50 nm AgNPs as a surface enhanced Raman scattering substrate to take the Raman scattering spectra of rhodamine B (RhB), glucose and viral pathogen (H5N1) at very low concentrations of 10-10 M, 10-12 M and 4 ng μl-1, respectively.

  14. Sizing of complex structure by the integration of several different optimal design algorithms

    Science.gov (United States)

    Sobieszczanski, J.

    1974-01-01

    Practical design of large-scale structures can be accomplished with the aid of the digital computer by bringing together in one computer program algorithms of nonlinear mathematical programing and optimality criteria with weight-strength and other so-called engineering methods. Applications of this approach to aviation structures are discussed with a detailed description of how the total problem of structural sizing can be broken down into subproblems for best utilization of each algorithm and for efficient organization of the program into iterative loops. Typical results are examined for a number of examples.

  15. Characterization of nano-sized SiC@Ni composite fabricated by electroless plating method.

    Science.gov (United States)

    Xu, Zhan; Chen, Yigang

    2013-02-01

    A nano-sized SiC@Ni composite was prepared by simple electroless plating method. Nickel can be reduced by Na2H2PO2 under the catalysis of Pd to despite onto the surface of SiC nanoparticles. The composite structure was characterized by means of TEM images, XRD and the components were analyzed using EDS. The coating layer on the SiC particles was several nanometers thick and mainly in a form of fine Ni crystalline grain and amorphous Ni-P alloy. By increasing the concentration of Na2H2PO2 in the plating bath, the uniformity of the coating layer can be improved obviously. Both of the magnetism and crystallinity of Ni coatings depends on the P content in the coating which can be decreased by increasing the pH values of plating solutions. The SiC@Ni particles exhibited soft magnetic characteristics.

  16. Evidence for the formation of different-sized nodules by different accretionary processes

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.; Karisiddaiah, S.M.

    Studies on different-sized polymetallic nodules from the Central Indian Ocean Basin reveal that chemical composition is largely related to the nodule diameter which show systematic decrease in Mn, Cu, and Ni content with increase in nodule size...

  17. Use of a magnetic fluid for particle size analysis by a sedimentation method

    Energy Technology Data Exchange (ETDEWEB)

    Dikansky, Yury [Department of Physics, Stavropol State University, 1 Pushkin Street, Stavropol 355009 (Russian Federation)], E-mail: dikansky@mail.ru; Zakinyan, Arthur; Bedganian, Marita [Department of Physics, Stavropol State University, 1 Pushkin Street, Stavropol 355009 (Russian Federation)

    2009-05-15

    A new method of particle size analysis of micrometer-sized particles is discussed. The improved method of sedimentation analysis with magnetic fluids has the potential and versatility to characterize polydisperse systems.

  18. Effect of a size-selective biomanipulation on nutrient release by gizzard shad in Florida (USA lakes

    Directory of Open Access Journals (Sweden)

    Schaus M.H.

    2013-11-01

    Full Text Available Although fish removal for biomanipulation is often highly size-selective, our understanding of the nutrient cycling effects of this size-selection is poor. To better understand these effects, we measured nutrient excretion by gizzard shad (Dorosoma cepedianum of differing sizes from four central Florida (USA lakes and combined these measures with gillnet biomass and size-structure data to compare lake-wide effects among lakes and years. Direct removal of P in fish tissue ranged from 0.16−1.00 kg·P·ha-1·yr-1. The estimated reduction in P excretion due to harvest ranged from 30.8−202.5 g·P·ha-1·month-1, with effects strongly tied to the biomass and size structure harvested. The amount of P release prevented per kg of fish removed was lower in previously unharvested lakes, due to the initial removal of larger fish with lower mass-specific excretion rates. Gill net mesh size impacted the size distribution of harvested fish, with smaller fish that excrete more P per gram being more vulnerable to smaller mesh sizes. In Lake Apopka, decreasing the mesh size by 1.3 cm yielded P excretion reductions that were 10.7−15.1% larger. Fish harvesting to reduce internal nutrient cycling can be most effective by increasing total harvest and by harvesting smaller size classes over multiple years.

  19. Shape-and size-controlled Ag nanoparticles stabilized by in situ generated secondary amines

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Meneses, E., E-mail: esther.ramirez@ibero.mx [Departamento de Ingeniería y Ciencias Químicas, Universidad Iberoamericana, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, Distrito Federal C.P. 01219 (Mexico); Montiel-Palma, V. [Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001 Col. Chamilpa, Cuernavaca, Morelos C.P. 62209 (Mexico); Domínguez-Crespo, M.A.; Izaguirre-López, M.G. [Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada-IPN, Unidad Altamira. Km 14.5 Carretera Tampico-Puerto Industrial, 89600 Altamira, Tamaulipas (Mexico); Palacios-Gonzalez, E. [Laboratorio de Microscopia de Ultra alta Resolución, Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas No. 152, C.P. 07730 México D.F. (Mexico); Dorantes-Rosales, H. [Departamento de Metalurgia, E.S.I.Q.I.E.-I.P.N., Unidad Profesional Adolfo López Mateos, Zacatenco, Delegación. Gustavo A. Madero, C.P. 07738 México D.F. (Mexico)

    2015-09-15

    Highlights: • Ag nanoparticles were generated from Ag amido complexes AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2}. • Ag nanoparticles were stabilized by in situ generated HN{sup i}Pr{sub 2} or HN(SiMe{sub 3}){sub 2}. • 1 or 5 equiv. of ethylenediamine as additional capping agent decreases the average size of the particles. • Ethylenediamine favor the formation of spherical particles. - Abstract: Silver amides such as AgN{sup i}Pr{sub 2} and AgN(SiMe{sub 3}){sub 2} have been employed successfully as precursors for the yield synthesis of silver nanoparticles under mild conditions of dihydrogen gas reduction (2 atm) in organic media. Transmission electron microscopy (TEM) showed the formation of silver nanoparticles with FCC structure, variously sized from 26 to 35 nm for AgN{sup i}Pr{sub 2} and from 14 to 86 nm for AgN(SiMe{sub 3}){sub 2}, the synthesis could take place in absence of added stabilizers due to the in situ formation of secondary amines from the reaction of dihydrogen gas with the amide ligands of the silver precursor. Indeed, the presence of HNR{sub 2} (R = iPr{sub 2}, N(SiMe{sub 3}){sub 2}) on the surface of the nanoparticle was confirmed by spectroscopic means. Finally, the addition of ethylenediamine as additional capping agent allowed not only the control of the structural characteristics of the resulting Ag nanoparticles (well-dispersed with spherical shape), but that regarding the nanoparticle size as it inhibited overgrowth, limiting it to ca. 25 nm.

  20. Remediation of copper contaminated soil by using different particle sizes of apatite: a field experiment.

    Science.gov (United States)

    Xing, Jinfeng; Hu, Tiantian; Cang, Long; Zhou, Dongmei

    2016-01-01

    The particle size of apatite is one of the critical factors that influence the adsorption of heavy metals on apatite in the remediation of heavy metal contaminated soils using apatite. However, little research has been done evaluating the impact of different particle sizes of apatite on immobilization remediation of heavy metal polluted soils in field. In this study, the adsorption isothermal experiments of copper on three kinds of apatite was tested, and the field experiment by using different particle sizes apatite [nano-hydroxyapatite (NAP), micro-hydroxyapatite (MAP), ordinary particle apatite (OAP)] at a same dosage of 25.8 t/ha (1.16 %, W/W) was also conducted. Ryegrass was chosen as the test plant. The ryegrass biomass, the copper contents in ryegrass and the copper fractionations in soil were determined after field experiments. Results of adsorption experiments showed that the adsorption amounts of copper on OAP was the lowest among different particles. The adsorption amounts of copper on MAP was higher than NAP at high copper equilibrium concentration (>1 mmol L(-1)), an opposite trend was obtained at low copper concentration (soil pH, decrease the available copper concentration in soil, provide more nutrient phosphate and promote the growth of ryegrass. The ryegrass biomass and the copper accumulation in ryegrass were the highest in MAP among all treatments. The effective order of apatite in phytoremediation of copper contaminated field soil was MAP > NAP > OAP, which was attributed to the high adsorption capacity of copper and the strong releasing of phosphate by MAP.

  1. Size characterization by Sedimentation Field Flow Fractionation of silica particles used as food additives

    Energy Technology Data Exchange (ETDEWEB)

    Contado, Catia, E-mail: Catia.Contado@unife.it [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy); Ravani, Laura [University of Ferrara, Department of Life Sciences and Biotechnologies, via L. Borsari, 46, 44121 Ferrara (Italy); Passarella, Martina [University of Ferrara, Department of Chemical and Pharmaceutical Sciences, via L. Borsari, 46, 44121 Ferrara (Italy)

    2013-07-25

    Graphical abstract: -- Highlights: •Four types of SiO{sub 2} particles were characterized by SdFFF, PCS and EM techniques. •Clusters of 10 nm nanoparticles were found in some SiO{sub 2} samples. •A method was set up to extract SiO{sub 2} particles from food matrices. •The effects of the carrier solution composition on SdFFF separations were evaluated. •Particle size distributions were obtained from SiO{sub 2} particles extracted from foodstuffs. -- Abstract: Four types of SiO{sub 2}, available on the market as additives in food and personal care products, were size characterized using Sedimentation Field Flow Fractionation (SdFFF), SEM, TEM and Photon Correlation Spectroscopy (PCS). The synergic use of the different analytical techniques made it possible, for some samples, to confirm the presence of primary nanoparticles (10 nm) organized in clusters or aggregates of different dimension and, for others, to discover that the available information is incomplete, particularly that regarding the presence of small particles. A protocol to extract the silica particles from a simple food matrix was set up, enriching (0.25%, w w{sup −1}) a nearly silica-free instant barley coffee powder with a known SiO{sub 2} sample. The SdFFF technique, in conjunction with SEM observations, made it possible to identify the added SiO{sub 2} particles and verify the new particle size distribution. The SiO{sub 2} content of different powdered foodstuffs was determined by graphite furnace atomic absorption spectroscopy (GFAAS); the concentrations ranged between 0.006 and 0.35% (w w{sup −1}). The protocol to isolate the silica particles was so applied to the most SiO{sub 2}-rich commercial products and the derived suspensions were separated by SdFFF; SEM and TEM observations supported the size analyses while GFAAS determinations on collected fractions permitted element identification.

  2. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    Science.gov (United States)

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting.

  3. Mechanical output of myosin II motors is regulated by myosin filament size and actin network mechanics

    Science.gov (United States)

    Stam, Samantha; Alberts, Jonathan; Gardel, Margaret; Munro, Edwin

    2013-03-01

    The interactions of bipolar myosin II filaments with actin arrays are a predominate means of generating forces in numerous physiological processes including muscle contraction and cell migration. However, how the spatiotemporal regulation of these forces depends on motor mechanochemistry, bipolar filament size, and local actin mechanics is unknown. Here, we simulate myosin II motors with an agent-based model in which the motors have been benchmarked against experimental measurements. Force generation occurs in two distinct regimes characterized either by stable tension maintenance or by stochastic buildup and release; transitions between these regimes occur by changes to duty ratio and myosin filament size. The time required for building force to stall scales inversely with the stiffness of a network and the actin gliding speed of a motor. Finally, myosin motors are predicted to contract a network toward stiffer regions, which is consistent with experimental observations. Our representation of myosin motors can be used to understand how their mechanical and biochemical properties influence their observed behavior in a variety of in vitro and in vivo contexts.

  4. Hardening by ion implantation of VT1-0 alloy having different grain size

    Energy Technology Data Exchange (ETDEWEB)

    Nikonenko, Alisa, E-mail: aliska-nik@mail.ru; Kurzina, Irina, E-mail: kurzina99@mail.ru [National Research Tomsk State University, 36, Lenin Str., 634050, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Str., 634050, Tomsk (Russian Federation); Kalashnikov, Mark, E-mail: kmp1980@mail.ru [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Akademicheskii Ave., 634021, Tomsk Russia (Russian Federation)

    2016-01-15

    The paper presents a transmission electron microscopy (TEM) study of the structural and phase state of commercially pure titanium implanted by aluminum ions. TEM study has been carried out for two types of grains, namely coarse (0.4 µm) and small (0.5 µm). This paper presents details of the yield stress calculations and the analysis of strength components for the both grain types in two areas of the modified layer: at a distance of 0-150 nm (surface area I) and ∼300 nm (central area II) from the irradiated surface. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress in areas I and II. Thus, near the ion-alloyed layer, the yield stress decreases with the increase of the grain size, whilst area II demonstrates its increase. Moreover, the contribution to the general hardening of the alloy made by certain hardening mechanisms differs from contributions made by each of these mechanisms in each certain case.

  5. Size fractionation characterisation of removed organics in reverse osmosis concentrates by ferric chloride.

    Science.gov (United States)

    Bagastyo, A Y; Keller, J; Batstone, D J

    2011-01-01

    Reverse osmosis membrane separation is the leading method for manufacturing potable purified water. It also produces a concentrate stream, namely reverse osmosis concentrates (ROC), with 10-20% of the water, and almost all other compounds. One method for further treating this stream is by coagulation with ferric chloride. This study evaluates removed organics in ROC treated with ferric chloride. Fractionation with ultrafiltration membranes allows separation of organics based on a nominal molecular weight. A stirred cell system was applied for serial fractionation to classify organic compounds into six groups of 10 kDa. The study found that raw ROC is rich in low molecular weight compounds (organics. These compounds include soluble microbial products (SMPs) and smaller humic and fulvic acids as indicated by fluorescence scanning. Conversely, colour was mostly contributed by medium to large molecules of humic and fulvic acids (> 0.5 kDa). Organics and colour were reduced in all molecular groups at an optimum treatment dose 1.48 mM FeCl3 and a pH of 5. However, ferric seemed to effectively remove colour in all size ranges while residual nitrogen was found mostly in the < 1 kDa sizes. Further, the fluorescence indicated that larger humic and fulvic acids were removed with considerable SMPs remaining in the < 0.5 kDa.

  6. Grain size stabilization of nanocrystalline copper at high temperatures by alloying with tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Darling, K.A., E-mail: kristopher.darling.civ@mail.mil [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005-5069 (United States); Roberts, A.J. [ORISE Program, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD 21005-5069 (United States); Mishin, Y. [George Mason University, Dept of Physics and Astronomy, Fairfax, VA 22030 (United States); Mathaudhu, S.N. [U.S. Army Research Laboratory, Army Research Office, Research Triangle Park, NC 27709-2211 (United States); Kecskes, L.J. [U.S. Army Research Laboratory, Weapons and Materials Research Directorate, Aberdeen Proving Ground, MD 21005-5069 (United States)

    2013-10-05

    Highlights: •A mean grain size of 167 nm is retained after annealing at 97% of the melting point. •Hardness surpasses conventional pure nanocrystalline Cu by 2.5 GPa. •Extreme stability is attributed to both thermodynamic and kinetic stabilization. -- Abstract: Nanocrystalline Cu–Ta alloys belong to an emerging class of immiscible materials with potential for high-temperature applications. Differential scanning calorimetry (DSC), Vickers microhardness, transmission and scanning electron microscopy (TEM/SEM), and atomistic simulations have been applied to study the structural evolution in high-energy cryogenically alloyed nanocrystalline Cu–10 at.%Ta. The thermally induced coarsening of the as-milled microstructure was investigated and it was found that the onset of grain growth occurs at temperatures higher than that for pure nanocrystalline Cu. The total heat release associated with grain growth was 0.553 kJ/mol. Interestingly, nanocrystalline Cu–10 at.%Ta maintains a mean grain size (GS) of 167 nm after annealing at 97% of its melting point. The increased microstructural stability is attributed to a combination of thermodynamic and kinetic stabilization effects which, in turn, appear to be controlled by segregation and diffusion of Ta solute atoms along grain boundaries (GBs). The as-milled nanocrystalline Cu–10 at.%Ta exhibits Vickers microhardness values near 5 GPa surpassing the microhardness of conventional pure nanocrystalline Cu by ∼2.5 GPa.

  7. Effects of micro-sized and nano-sized WO3 on mass attenauation coefficients of concrete by using MCNPX code.

    Science.gov (United States)

    Tekin, H O; Singh, V P; Manici, T

    2017-03-01

    In the present work the effect of tungsten oxide (WO3) nanoparticles on mass attenauation coefficients of concrete has been investigated by using MCNPX (version 2.4.0). The validation of generated MCNPX simulation geometry has been provided by comparing the results with standard XCOM data for mass attenuation coefficients of concrete. A very good agreement between XCOM and MCNPX have been obtained. The validated geometry has been used for definition of nano-WO3 and micro-WO3 into concrete sample. The mass attenuation coefficients of pure concrete and WO3 added concrete with micro-sized and nano-sized have been compared. It was observed that shielding properties of concrete doped with WO3 increased. The results of mass attenauation coefficients also showed that the concrete doped with nano-WO3 significanlty improve shielding properties than micro-WO3. It can be concluded that addition of nano-sized particles can be considered as another mechanism to reduce radiation dose.

  8. Synthesis of Large-Sized Single-Crystal Hexagonal Boron Nitride Domains on Nickel Foils by Ion Beam Sputtering Deposition.

    Science.gov (United States)

    Wang, Haolin; Zhang, Xingwang; Liu, Heng; Yin, Zhigang; Meng, Junhua; Xia, Jing; Meng, Xiang-Min; Wu, Jinliang; You, Jingbi

    2015-12-22

    Large-sized single-crystal h-BN domains with a lateral size up to 100 μm are synthesized on Ni foils by ion-beam sputtering deposition. The nucleation density of h-BN is dramatically decreased by reducing the concentrations of both active sites and species on the Ni surface through a brief in situ pretreatment of the substrate and optimization of the growth parameters, enabling the growth of large-sized domains.

  9. Numerical simulation of particle dynamics in an orifice-electrode system. Application to counting and sizing by impedance measurement.

    Science.gov (United States)

    Isèbe, Damien; Nérin, Philippe

    2013-04-01

    This paper describes how to numerically tackle the problem of counting and sizing particles by impedance measurement in an orifice-electrode system. The model allows to simulate the particle dynamics submitted to strong hydrodynamic stresses through a microorifice and to compute the voltage pulses generated by the modification of the inner dielectric medium. This approach gives important information about particles size distribution and allows to quantify the role of trajectory and orientation of particles on the size measurement.

  10. Lysozyme refolding at high concentration by dilution and size-exclusion chromatography

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    This study of renaturation by dilution and size exclusion chromatography (SEC) addition of urea to improve yield as well as the initial and final protein concentrations showed that although urea decreased the rate of lysozyme refolding, it could suppress protein aggregation to sustain the pathway of correct refolding at high protein concentration; and that there existed an optimum urea concentration in renaturation buffer. Under the above conditions, lysozyme was successfully refolded from initial concentration of up to 40 mg/mL by dilution and 100 mg/mL by SEC, with the yield of the former being more than 40% and that of the latter being 34.8%. Especially, under the condition of 30 min interval time, i.e. τ>2(tR2-tR1), the efficiency was increased by 25% and the renaturation buffer could be recycled for SEC refolding in continuous operation of downstream process.

  11. The simulation and error analysis of raindrop size distribution obtained by micro rain radar

    Institute of Scientific and Technical Information of China (English)

    JIANG; Shiyang; GAO; Taichang; LIU; Xichuan

    2015-01-01

    Observation of raindrop size distribution( DSD) with a vertically pointing micro rain radar( MRR) has important significance in the precipitation measurement field. The Mie scattering of large particle,vertical wind and air turbulence have great influences on the retrieval of DSD measured by MRR. This paper simulates the process of how three factors affect the inversion of DSD and the calculation of other precipitation parameters,then makes the errors analysis. Because the wavelength of MRR is 12.5mm,M ie theory is more suitable for the precipitation particle than Rayleigh approximation,w hich may cause the underestimation of number density of small droplets and the overestimation of that in middle field. The vertical wind results in inaccurate estimation of particle terminal velocity,so the diameter is measured with some errors by empirical relationship,w hich affects the calculating accuracy of radar reflectivity and rain rate. Air turbulence can broaden the pow er spectral density,of which the impact on the inversion of DSD are concentrated in small droplets field. Then the measured data from MRR is analyzed and the results prove the impacts of those factors. Finally,according to the analysis and application limits,the prospect of the future research trend of particle size distribution is conducted.

  12. Time course of the size of the dark area in macular holes by scanning laser ophthalmoscopy.

    Science.gov (United States)

    Akasaka, Y; Nishikawa, S; Tamai, M

    2000-02-01

    To investigate the time course of idiopathic macular hole development by scanning laser ophthalmoscopy (SLO), we examined 28 eyes of 25 patients with macular holes. Cases included four eyes with stage 1-B disease (foveal detachment), 3 with stage 2 (break at the fovea), 13 with stage 3 (full-thickness macular hole), and 8 with stage 4 (hole with pseudo-operculum, posterior vitreous detachment), according to Gass's classification. The diameter of the dark area around the macular holes was recorded by SLO using a helium-neon laser. We compared the percent difference of dark area recorded between initial findings and these after three months. The size of the dark area increased after three months in eyes with stages 1, 2, and 3 disease. The size of the dark area in stage 4 disease decreased after 3 months. In the stage before posterior vitreous detachment (PVD), the dark areas increased. Once PVD occurred, these areas decreased. These findings suggested that the time course of the dark area may be related to the development of PVD.

  13. Preparation of nanometer-sized black iron oxide pigment by recycling of blast furnace flue dust.

    Science.gov (United States)

    Shen, Lazhen; Qiao, Yongsheng; Guo, Yong; Tan, Junru

    2010-05-15

    Blast furnace (BF) flue dust is one of pollutants emitted by iron and steel plants. The recycling of BF flue dust can not only reduce pollution but also bring social and environmental benefits. In this study, leaching technique was employed to the treatment of BF flue dust at first. A mixed solution of ferrous and ferric sulfate was obtained and used as raw material to prepare nanometer-sized black iron oxide pigment (Fe(3)O(4), magnetite) with NaOH as precipitant. The optimal technological conditions including total iron ion concentration, Fe(3+)/Fe(2+) mole ratio, precipitant concentration and reaction temperature were studied and discussed carefully. The spectral reflectance and oil absorption were used as major parameters to evaluate performance of pigment. Furthermore, Fe(3)O(4) particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Under optimized conditions obtained pigment has low average spectral reflectance (<4%), good oil absorption ( approximately 23%), high black intensity, and narrow size distribution 60-70 nm.

  14. Evaluating sequence-derived mtDNA length heteroplasmy by amplicon size analysis

    Science.gov (United States)

    Berger, C.; Hatzer-Grubwieser, P.; Hohoff, C.; Parson, W.

    2011-01-01

    Length heteroplasmy (LH) in mitochondrial (mt)DNA is usually observed in homopolymeric tracts and manifest as mixture of various length variants. The generally used difference-coded annotation to report mtDNA haplotypes does not express the degree of LH variation present in a sample, even more so, it is sometimes difficult to establish which length variants are present and clearly distinguishable from background noise. It has therefore become routine practice for some researchers to call the dominant type, the “major molecule”, which represents the LH variant that is most abundant in a DNA extract. In the majority of cases a clear single dominant variant can be identified. However, in some samples this interpretation is difficult, i.e. when (almost) equally quantitative LH variants are present or when multiple sequencing primers result in the presentation of different dominant types. To better understand those cases we designed amplicon sizing assays for the five most relevant LH regions in the mtDNA control region (around ntps 16,189, 310, 460, 573, and the AC-repeat between 514 and 524) to determine the ratio of the LH variants by fluorescence based amplicon sizing assays. For difficult LH constellations derived by Sanger sequencing (with Big Dye terminators) these assays mostly gave clear and unambiguous results. In the vast majority of cases we found agreement between the results of the sequence and amplicon analyses and propose this alternative method in difficult cases. PMID:21067985

  15. Priming effects in aggregate size fractions induced by glucose addition and grinding

    Science.gov (United States)

    Tian, Jing; Blagodatskaya, Evgenia; Pausch, Johanna; Kuzaykov, Yakov

    2014-05-01

    It is widely recognized that soil organic matter (SOM) mineralization can be accelerated (positive priming) or retarded (negative priming) by addition of easily available substrates to soil. SOM is a heterogeneous mixture, which contains numerous compounds with different degradability and turnover rates times. Nevertheless, so far, there is still lack of knowledge on identifying single fractions of the SOM as the source of C and N released by priming effects. The aim of this study was to determine the priming effect as related to different aggregate fractions, aggregate disruption and the amounts of substrate. In a 49 days incubation experiment, the soil samples were separated into three aggregate fractions (>2 mm, 2-0.25 mm and 0.25 mm) than in the microaggregates (priming effect increased as added glucose increased in all intact aggregate size, and highest priming effect was observed in >2 mm fraction. However, the magnitude of priming effect response to glucose addition depended on the aggregate size after grinding. This study demonstrates that substrate amounts, aggregate fractionation and grinding can have obvious impacts on priming effect, indicating important implications for understanding SOM cycling and stability.

  16. Characterization of Particle Size Distributions of Powdery Building Material Aerosol Generated by Fluidization and Gravitation

    Directory of Open Access Journals (Sweden)

    Tadas Prasauskas

    2012-10-01

    Full Text Available This study aims to identify particle size distributions (PSD of aerosol of powdery building materials commonly used in construction work (cement, chalk, clay, wood sawdust, wood grinding dust, gypsum, hydrated lime, masonry grout, quartz sand, sand and structural lime by two aerosolization methods: fluidization and gravitation. Fluidization and gravitation methods represent industrial activities such as pneumotransportation and unloading. Both particle resuspension mechanisms have been modelled in laboratory conditions. The particle size distributions of resuspended particulate matter from powdery building materials were rather similar identified by both fluidization and gravitation methods, with an exception of wood sawdust and sand. The PM10 fraction ranged between 30% and 87%, PM2.5 from 7% to 28% and PM1.0 from 3% to 7% of the total mass of particulate matter. The highest PM10/PMtotal ratio was calculated for masonry grout - 0.87, and the lowest ratio for quartz sand - 0.30. The highest ratio of PM2.5/PMtotal was calculated for sand - 0.23, the lowest for quartz sand - 0.07. Substantial quantities of PM2.5 were found to be emitted implying a potential threat to human health.DOI: http://dx.doi.org/10.5755/j01.erem.61.3.1519

  17. Influence of dose on particle size of colloidal silver nanoparticles synthesized by gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Naghavi, Kazem, E-mail: Kazem.naghavi@gmail.co [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Saion, Elias [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia); Rezaee, Khadijeh [Department of Nuclear Engineering, Faculty of Modern Sciences and Technologies, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Yunus, Wan Mahmood Mat [Universiti Putra Malaysia, Physics Department, 43400 UPM SERDANG, Selangor (Malaysia)

    2010-12-15

    Colloidal silver nanoparticles were synthesized by {gamma}-irradiation-induced reduction method of an aqueous solution containing silver nitrate as a precursor in various concentrations between 7.40x10{sup -4} and 1.84x10{sup -3} M, polyvinyl pyrrolidone for capping colloidal nanoparticles, isopropanol as radical scavenger of hydroxyl radicals and deionised water as a solvent. The irradiations were carried out in a {sup 60}Co {gamma} source chamber at doses up to 70 kGy. The optical absorption spectra were measured using UV-vis spectrophotometer and used to study the particle distribution and electronic structure of silver nanoparticles. As the radiation dose increases from 10 to 70 kGy, the absorption intensity increases with increasing dose. The absorption peak {lambda}{sub max} blue shifted from 410 to 403 nm correspond to the increase of absorption conduction electron energy from 3.02 to 3.08 eV, indicating the particle size decreases with increasing dose. The particle size was determined by photon cross correlation spectroscopy and the results showed that the particle diameter decreases exponentially with the increase of dose. The transmission electron microscopy images were taken at doses of 20 and 60 kGy and the results confirmed that as the dose increases the diameter of colloidal silver nanoparticle decreases and the particle distribution increases.

  18. Molecular strain typing of Brucella abortus isolates from Italy by two VNTR allele sizing technologies.

    Science.gov (United States)

    De Santis, Riccardo; Ancora, Massimo; De Massis, Fabrizio; Ciammaruconi, Andrea; Zilli, Katiuscia; Di Giannatale, Elisabetta; Pittiglio, Valentina; Fillo, Silvia; Lista, Florigio

    2013-10-01

    Brucellosis, one of the most important re-emerging zoonoses in many countries, is caused by bacteria belonging to the genus Brucella. Furthermore these bacteria represent potential biological warfare agents and the identification of species and biovars of field strains may be crucial for tracing back source of infection, allowing to discriminate naturally occurring outbreaks instead of bioterrorist events. In the last years, multiple-locus variable-number tandem repeat analysis (MLVA) has been proposed as complement of the classical biotyping methods and it has been applied for genotyping large collections of Brucella spp. At present, the MLVA band profiles may be resolved by automated or manual procedures. The Lab on a chip technology represents a valid alternative to standard genotyping techniques (as agarose gel electrophoresis) and it has been previously used for Brucella genotyping. Recently, a new high-throughput genotyping analysis system based on capillary gel electrophoresis, the QIAxcel, has been described. The aim of the study was to evaluate the ability of two DNA sizing equipments, the QIAxcel System and the Lab chip GX, to correctly call alleles at the sixteen loci including one frequently used MLVA assay for Brucella genotyping. The results confirmed that these technologies represent a meaningful advancement in high-throughput Brucella genotyping. Considering the accuracy required to confidently resolve loci discrimination, QIAxcel shows a better ability to measure VNTR allele sizes compared to LabChip GX.

  19. Optimization of Comminution Circuit Throughput and Product Size Distribution by Simulation and Control

    Energy Technology Data Exchange (ETDEWEB)

    S.K. Kawatra; T.C. Eisele; T. Weldum; D. Larsen; R. Mariani; J. Pletka

    2005-07-01

    The goal of this project was to improve energy efficiency of industrial crushing and grinding operations (comminution). Mathematical models of the comminution process were used to study methods for optimizing the product size distribution, so that the amount of excessively fine material produced could be minimized. The goal was to save energy by reducing the amount of material that was ground below the target size, while simultaneously reducing the quantity of materials wasted as ''slimes'' that were too fine to be useful. Extensive plant sampling and mathematical modeling of the grinding circuits was carried out to determine how to correct this problem. The approaches taken included (1) Modeling of the circuit to determine process bottlenecks that restrict flowrates in one area while forcing other parts of the circuit to overgrind the material; (2) Modeling of hydrocyclones to determine the mechanisms responsible for retaining fine, high-density particles in the circuit until they are overground, and improving existing models to accurately account for this behavior; and (3) Evaluation of the potential of advanced technologies to improve comminution efficiency and produce sharper product size distributions with less overgrinding. The mathematical models were used to simulate novel circuits for minimizing overgrinding and increasing throughput, and it is estimated that a single plant grinding 15 million tons of ore per year saves up to 82.5 million kWhr/year, or 8.6 x 10{sup 11} BTU/year. Implementation of this technology in the midwestern iron ore industry, which grinds an estimated 150 million tons of ore annually to produce over 50 million tons of iron ore concentrate, would save an estimated 1 x 10{sup 13} BTU/year.

  20. Molecular mass ranges of coal tar pitch fractions by mass spectrometry and size-exclusion chromatography.

    Science.gov (United States)

    Karaca, F; Morgan, T J; George, A; Bull, I D; Herod, A A; Millan, M; Kandiyoti, R

    2009-07-01

    A coal tar pitch was fractionated by solvent solubility into heptane-solubles, heptane-insoluble/toluene-solubles (asphaltenes), and toluene-insolubles (preasphaltenes). The aim of the work was to compare the mass ranges of the different fractions by several different techniques. Thermogravimetric analysis, size-exclusion chromatography (SEC) and UV-fluorescence spectroscopy showed distinct differences between the three fractions in terms of volatility, molecular size ranges and the aromatic chromophore sizes present. The mass spectrometric methods used were gas chromatography/mass spectrometry (GC/MS), pyrolysis/GC/MS, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) and laser desorption time-of-flight mass spectrometry (LD-TOFMS). The first three techniques gave good mass spectra only for the heptane-soluble fraction. Only LDMS gave signals from the toluene-insolubles, indicating that the molecules were too involatile for GC and too complex to pyrolyze into small molecules during pyrolysis/GC/MS. ESI-FTICRMS gave no signal for toluene-insolubles probably because the fraction was insoluble in the methanol or acetonitrile, water and formic acid mixture used as solvent to the ESI source. LDMS was able to generate ions from each of the fractions. Fractionation of complex samples is necessary to separate smaller molecules to allow the use of higher laser fluences for the larger molecules and suppress the formation of ionized molecular clusters. The upper mass limit of the pitch was determined as between 5000 and 10,000 u. The pitch asphaltenes showed a peak of maximum intensity in the LDMS spectra at around m/z 400, in broad agreement with the estimate from SEC. The mass ranges of the toluene-insoluble fraction found by LDMS and SEC (400-10,000 u with maximum intensity around 2000 u by LDMS and 100-9320 u with maximum intensity around 740 u by SEC) are higher than those for the asphaltene fraction (200-4000 u with

  1. Rapid Synthesis of Size-controlled Gold Nanoparticles by Complex Intramolecular Photoreduction

    Institute of Scientific and Technical Information of China (English)

    DONG Shou-an; YANG Sheng-chun; TANG Chun

    2007-01-01

    A rapid synthesis of size-controlled gold nanoparticles was proposed. The method is based on the sensitive intramolecular photoreduction reaction of Fe( Ⅲ )-EDTA complex in chloroacetic acid-sodium acetate buffer solution,where Fe(Ⅱ)-EDTA complex generated by photo-promotion acts as a reductant of AuCl4- ions. Gold nanoparticles formed were stabilized by EDTA ligand or other protective agents added. As a result, well-dispersed gold nanoparticles with an average diameter range of 6.7 to 50. 9 nm were obtained. According to the characterizations by the UV spectrum and TEM, the intramolecular charge transfer of the excited states of complex Fe(Ⅲ) -EDTA and the mechanism of forming gold nanoparticles were discussed in detail.

  2. Dislocation Analysis for Large-sized Sapphire Single Crystal Grown by SAPMAC Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, large-sized sapphire (Φ230×210 mm, 27.5 kg) was grown by SAPMAC method (sapphire growth technique with micro-pulling and shoulder-expanding at the cooled center). Dislocation peculiarity in large sapphire boule (0001) basal plane was investigated by chemical etching, scanning electron microscopy and X-ray topography method. The triangular dislocation etch pit measured is 7.6×101~8.0×102 cm-2, in which relative high-density dislocations were generated at both initial and final stages of crystal growth. The analysis of single-crystal X-ray topography shows that there are no apparent sub-grain boundaries; the dislocation lines are isolated and straight. Finally, the origins of low-density dislocation in sapphire crystal are discussed by numerical analysis method.

  3. Micrometer size rod formed by secondary self assembly of omeprazole with α- and β-cyclodextrins

    Science.gov (United States)

    Rajendiran, N.; Venkatesh, G.

    2015-02-01

    Self assembly of α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD) micro rods induced by omeprazole (OMP) were observed by SEM and TEM. OMP/CD inclusion complexes have formed the secondary self assembly micro meter size rod like structure. This structure was driven by the intermolecular hydrogen bonding as well as van der Waals forces. Both forces induced the ordered assembly and arrangement of OMP/CD inclusion complexes, whereas CD molecules acted as molecular bricks. The OMP/CD inclusion complexes primary assembled form individual nanorods and then secondary self aggregate nanorods were form a micro meter rod structure. The results indicate that inter-nanotubular hydrogen bonding plays a crucial role in the formation of the self assembled micro rods. The inclusion complexes were also characterized using FT-IR, DSC, powder XRD, 1H NMR, absorption, fluorescence, life time measurements and molecular modeling methods.

  4. Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Ali Nakhaei Pour; Elham Hosaini; Mohammad Izadyar; Mohammad Reza Housaindokht

    2015-01-01

    The effect of Co particle size on the Fischer-Tropsch synthesis (FTS) activity of carbon nanotube (CNT)-supported Co catalysts was investigated. Microemulsion (using water-to-surfactant molar ratios of 2 to12) and impregnation techniques were used to prepare catalysts with different Co particle sizes. Kinetic studies were performed to understand the effect of Co particle size on catalytic activity. Size-dependent kinetic parameters were developed using a thermodynamic method, to evaluate the structural sensitivity of the CNT-supported Co catalysts. The size-independent FTS reaction rate constant and size-independent adsorption parameter increased with increasing reac-tion temperature. The Polani parameter also depended on catalyst particle size, because of changes in the catalyst surface coverage.

  5. The critical size is set at a single-cell level by growth rate to attain homeostasis and adaptation.

    Science.gov (United States)

    Ferrezuelo, Francisco; Colomina, Neus; Palmisano, Alida; Garí, Eloi; Gallego, Carme; Csikász-Nagy, Attila; Aldea, Martí

    2012-01-01

    Budding yeast cells are assumed to trigger Start and enter the cell cycle only after they attain a critical size set by external conditions. However, arguing against deterministic models of cell size control, cell volume at Start displays great individual variability even under constant conditions. Here we show that cell size at Start is robustly set at a single-cell level by the volume growth rate in G1, which explains the observed variability. We find that this growth-rate-dependent sizer is intimately hardwired into the Start network and the Ydj1 chaperone is key for setting cell size as a function of the individual growth rate. Mathematical modelling and experimental data indicate that a growth-rate-dependent sizer is sufficient to ensure size homeostasis and, as a remarkable advantage over a rigid sizer mechanism, it reduces noise in G1 length and provides an immediate solution for size adaptation to external conditions at a population level.

  6. Pore-size-dependent calcium carbonate precipitation controlled by surface chemistry.

    Science.gov (United States)

    Stack, Andrew G; Fernandez-Martinez, Alejandro; Allard, Lawrence F; Bañuelos, José L; Rother, Gernot; Anovitz, Lawrence M; Cole, David R; Waychunas, Glenn A

    2014-06-03

    Induced mineral precipitation is potentially important for the remediation of contaminants, such as during mineral trapping during carbon or toxic metal sequestration. The prediction of precipitation reactions is complicated by the porous nature of rocks and soils and their interaction with the precipitate, introducing transport and confinement effects. Here X-ray scattering measurements, modeling, and electron microscopies were used to measure the kinetics of calcium carbonate precipitation in a porous amorphous silica (CPG) that contained two discrete distributions of pore sizes: nanopores and macropores. To examine the role of the favorability of interaction between the substrate and precipitate, some of the CPG was functionalized with a self-assembled monolayer (SAM) similar to those known to enhance nucleation densities on planar substrates. Precipitation was found to occur exclusively in macropores in the native CPG, while simultaneous precipitation in nanopores and macropores was observed in the functionalized CPG. The rate of precipitation in the nanopores estimated from the model of the X-ray scattering matched that measured on calcite single crystals. These results suggest that the pore-size distribution in which a precipitation reaction preferentially occurs depends on the favorability of interaction between substrate and precipitate, something not considered in most studies of precipitation in porous media.

  7. Measurement of the aortic annulus size by real-time three-dimensional transesophageal echocardiography.

    Science.gov (United States)

    Jánosi, Rolf Alexander; Kahlert, Philipp; Plicht, Björn; Wendt, Daniel; Eggebrecht, Holger; Erbel, Raimund; Buck, Thomas

    2011-04-01

    We sought to determine the level of agreement and the reproducibility of two-dimensional (2D) transthoracic (2D-TTE), 2D transesophageal (2D-TEE) and real-time three-dimensional (3D) transesophageal echocardiography (RT3D-TEE) for measurement of aortic annulus size in patients referred for transcatheter aortic valve implantation (TAVI). Accurate preoperative assessment of the dimensions of the aortic annulus is critical for patient selection and successful implantation in those undergoing TAVI for severe aortic stenosis (AS). Annulus size was measured using 2D-TTE, 2D-TEE and RT3D-TEE in 105 patients with severe AS referred for TAVI. Agreement between echocardiographic methods and interobserver variability was assessed using the Bland-Altman method and regression analysis, respectively. The mean aortic annuli were 21,7 ± 3 mm measured with 2D-TTE, 22,6 ± 2,8 mm with 2D-TEE and 22,3 ± 2,9 mm with RT3D-TEE. The results showed a small but significant mean difference and a strong correlation between the three measurement techniques (2D-TTE vs. 2D-TEE mean difference 0,84 ± 1,85 mm, r = 0,8, p annulus measured by 2D-TTE, 2D-TEE and RT3D-TEE. Thus, in patients referred for TAVI, the echocardiographic method used may have an impact on TAVI strategy.

  8. The REVEILLE clock genes inhibit growth of juvenile and adult plants by control of cell size.

    Science.gov (United States)

    Gray, Jennifer A; Shalit-Kaneh, Akiva; Chu, Dalena Nhu; Hsu, Polly Yingshan; Harmer, Stacey

    2017-03-02

    The circadian clock is a complex regulatory network that enhances plant growth and fitness in a constantly changing environment. In Arabidopsis thaliana, the clock is comprised of numerous regulatory feedback loops in which REVEILLE8 (RVE8) and its homologs RVE4 and RVE6 act in a partially redundant manner to promote clock pace. Here, we report that the remaining members of the RVE8 clade, RVE3 and RVE5, play only minor roles in regulation of clock function. However, we find that RVE8 clade proteins have unexpected functions in modulation of light input to the clock and control of plant growth at multiple stages of development. In seedlings, these proteins repress hypocotyl elongation in a day-length and sucrose dependent manner. Strikingly, adult rve4 6 8 and rve3 4 5 6 8 mutants are much larger than wild type, with both increased leaf area and biomass. This size phenotype is associated with a faster growth rate and larger cell size and is not simply due to a delay in the transition to flowering. Gene expression and epistasis analysis reveal that the growth phenotypes of rve mutants are due to misregulation of PHYTOCHROME INTERACTING FACTOR4 (PIF4) and PIF5 expression. Our results shows that even small changes in PIF gene expression caused by perturbation of clock gene function can have large effects on the growth of adult plants.

  9. Estimating required information size by quantifying diversity in random-effects model meta-analyses

    DEFF Research Database (Denmark)

    Wetterslev, Jørn; Thorlund, Kristian; Brok, Jesper;

    2009-01-01

    an intervention effect suggested by trials with low-risk of bias. METHODS: Information size calculations need to consider the total model variance in a meta-analysis to control type I and type II errors. Here, we derive an adjusting factor for the required information size under any random-effects model meta......-analysis. RESULTS: We devise a measure of diversity (D2) in a meta-analysis, which is the relative variance reduction when the meta-analysis model is changed from a random-effects into a fixed-effect model. D2 is the percentage that the between-trial variability constitutes of the sum of the between...... and interpreted using several simulations and clinical examples. In addition we show mathematically that diversity is equal to or greater than inconsistency, that is D2 >or= I2, for all meta-analyses. CONCLUSION: We conclude that D2 seems a better alternative than I2 to consider model variation in any random...

  10. Study of droplet size and velocity of fuel containing CO2 spray by means of PDA

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin; QIAO Xinqi; HUANG Zhen; FANG Junhua

    2004-01-01

    Injection of fuel containing CO2 has potential to reduce NOx and soot emissions in a diesel engine. This paper presents an experimental study on the spray characteristics of fuel containing CO2 as measured by phase doppler anemometry (PDA). Experiments were performed under atmospheric conditions on diesel hole-type nozzles at constant injection pressure. Effects of CO2 concentration in diesel fuel on the spray pattern, droplet size and velocity were measured. Experimental results show that fuel atomization will improve greatly when the concentration of dissolved CO2 in the fuel exceeds the critical value. The axial and radial velocity of the fuel spray containing CO2 is larger than that of conventional diesel fuel spray near the nozzle exit due to flash boiling phenomena. Downstream of the spray, the radial velocity and droplet size of fuel containing CO2 is much more uniform and smaller than that of pure diesel spray. It is attributed to the greatly enhanced liquid-gas mixing resulting from flash separation of CO2 from the liquid. New insight into the atomization of the fuel containing CO2 was obtained and a possible mechanism to explain the phenomena was proposed. The method may be developed into a new technique for controlling diesel combustion and exhaust emissions.

  11. Built Environment Influences of Children's Physical Activity: Examining Differences by Neighbourhood Size and Sex.

    Science.gov (United States)

    Mitchell, Christine A; Clark, Andrew F; Gilliland, Jason A

    2016-01-15

    Neighbourhoods can facilitate or constrain moderate-to-vigorous physical activity (MVPA) among children by providing or restricting opportunities for MVPA. However, there is no consensus on how to define a child's neighbourhood. This study examines the influence of the neighbourhood built environment on objectively measured MVPA among 435 children (aged 9-14 years) in London (ON, Canada). As there is no consensus on how to delineate a child's neighbourhood, a geographic information system was used to generate measures of the neighbourhood built environment at two buffer sizes (500 m and 800 m) around each child's home. Linear regression models with robust standard errors (cluster) were used to analyze the relationship between built environment characteristics and average daily MVPA during non-school hours on weekdays. Sex-stratified models assessed sex-specific relationships. When accounting for individual and neighbourhood socio-demographic variables, park space and multi-use path space were found to influence children's MVPA. Sex-stratified models found significant associations between MVPA and park space, with the 800 m buffer best explaining boys' MVPA and the 500 m buffer best explaining girls' MVPA. Findings emphasize that, when designing built environments, programs, and policies to facilitate physical activity, it is important to consider that the size of the neighbourhood influencing a child's physical activity may differ according to sex.

  12. Micron-Sized Particles Detected in the Vicinity of Jupiter by the Voyager Plasma Wave Instruments

    Science.gov (United States)

    Tsintikidis, D.; Gurnett, D. A.; Kurth, W. S.; Granroth, L. J.

    1996-01-01

    Wideband waveform data obtained by the plasma wave instruments onboard the Voyager 1 and 2 spacecraft have been used to study micron-sized dust particles in the vicinity of Jupiter. The technique used was developed during the flybys of Saturn, Uranus, and Neptune, and makes use of the fact that a particle striking the spacecraft at 10-20 km/s causes a voltage pulse in the plasma wave receiver. The waveform of the voltage pulse is much different than the waveform of plasma waves and provides a highly reliable method of detecting micron-sized dust particles. Although the dust impact rate observed in the vicinity of Jupiter is much lower than the rates at Saturn, Uranus, and Neptune, the particles are easily detectable. Approximately 1200 48-second frames of wideband waveform data were examined in the vicinity of Jupiter. Dust impact signatures were found in approximately 20% of these frames. The peak impact rates are about 1 impact per second, and the peak number densities are about 10(exp -5) m(exp -3). Most of the impacts occurred near the equatorial plane at radial distances less than about 35 R(sub j) from Jupiter. Analysis of the detection threshold indicates that the particles have masses greater than 10(exp -11) g, which corresponds to particles with diameters of a few micrometers or larger.

  13. Curvature of double-membrane organelles generated by changes in membrane size and composition.

    Directory of Open Access Journals (Sweden)

    Roland L Knorr

    Full Text Available Transient double-membrane organelles are key players in cellular processes such as autophagy, reproduction, and viral infection. These organelles are formed by the bending and closure of flat, double-membrane sheets. Proteins are believed to be important in these morphological transitions but the underlying mechanism of curvature generation is poorly understood. Here, we describe a novel mechanism for this curvature generation which depends primarily on three membrane properties: the lateral size of the double-membrane sheets, the molecular composition of their highly curved rims, and a possible asymmetry between the two flat faces of the sheets. This mechanism is evolutionary advantageous since it does not require active processes and is readily available even when resources within the cell are restricted as during starvation, which can induce autophagy and sporulation. We identify pathways for protein-assisted regulation of curvature generation, organelle size, direction of bending, and morphology. Our theory also provides a mechanism for the stabilization of large double-membrane sheet-like structures found in the endoplasmic reticulum and in the Golgi cisternae.

  14. The Kilometer-Sized Main Belt Asteroid Population as Revealed by Spitzer

    CERN Document Server

    Ryan, Erin Lee; Shenoy, Sachindev S; Woodward, Charles E; Carey, Sean; Noriega-Crespo, Alberto; Kraemer, Kathleen E; Price, Stephan D

    2012-01-01

    Multi-epoch Spitzer Space Telescope 24 micron data is utilized from the MIPSGAL and Taurus Legacy surveys to detect asteroids based on their relative motion. These infrared detections are matched to known asteroids and rotationally averaged diameters and albedos are derived using the Near Earth Asteroid Model (NEATM) in conjunction with Monte Carlo simulations for 1835 asteroids ranging in size from 0.2 to 143.6 km. A small subsample of these objects was also detected by IRAS or MSX and the single wavelength albedo and diameter fits derived from this data are within 5% of the IRAS and/or MSX derived albedos and diameters demonstrating the robustness of our technique. The mean geometric albedo of the small main belt asteroids in this sample is p_V = 0.138 with a sample standard deviation of 0.105. The albedo distribution of this sample is far more diverse than the IRAS or MSX samples. The cumulative size-frequency distribution of asteroids in the main belt at small diameters is directly derived. Completeness l...

  15. Scaling of heat production by thermogenic flowers: limits to floral size and maximum rate of respiration.

    Science.gov (United States)

    Seymour, Roger S

    2010-09-01

    Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, micromol s(-1)) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW degrees C(-1)) for spadices scales according to C = 18.5M(0.73). Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass-specific rates of respiration are variable between species, but reach 900 nmol s(-1) g(-1) in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass-specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass-specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.

  16. Quantum size effects in TiO2 thin films grown by atomic layer deposition

    Directory of Open Access Journals (Sweden)

    Massimo Tallarida

    2014-01-01

    Full Text Available We study the atomic layer deposition of TiO2 by means of X-ray absorption spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are influenced by quantum size effects. The modified electronic properties may play an important role in charge carrier transport and separation, and increase the efficiency of energy conversion systems.

  17. Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet

    Directory of Open Access Journals (Sweden)

    M. Hamrin

    2009-11-01

    Full Text Available In this article, and in a companion paper by Hamrin et al. (2009 [Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs in Earth's plasma sheet. From more than 80 Cluster plasma sheet crossings (660 h data at the altitude of about 15–20 RE in the summer and fall of 2001, we have identified 116 Concentrated Load Regions (CLRs and 35 Concentrated Generator Regions (CGRs. By examining variations in the power density, E·J, where E is the electric field and J is the current density obtained by Cluster, we have estimated typical values of the scale size and life time of the CLRs and the CGRs. We find that a majority of the observed ECRs are rather stationary in space, but varying in time. Assuming that the ECRs are cylindrically shaped and equal in size, we conclude that the typical scale size of the ECRs is 2 RE≲ΔSECR≲5 RE. The ECRs hence occupy a significant portion of the mid altitude plasma sheet. Moreover, the CLRs appear to be somewhat larger than the CGRs. The life time of the ECRs are of the order of 1–10 min, consistent with the large scale magnetotail MHD simulations of Birn and Hesse (2005. The life time of the CGRs is somewhat shorter than for the CLRs. On time scales of 1–10 min, we believe that ECRs rise and vanish in significant regions of the plasma sheet, possibly oscillating between load and generator character. It is probable that at least some of the observed ECRs oscillate energy back and forth in the plasma sheet instead of channeling it to the ionosphere.

  18. Size-frequency distribution of different secondary crater populations: 1. Equilibrium caused by secondary impacts

    Science.gov (United States)

    Xiao, Zhiyong

    2016-12-01

    Accumulation of impact craters is the major reason causing equilibrium of crater populations on airless planetary surfaces. Besides primary craters, the effect of widespread secondaries on the equilibrium of local crater populations is little studied. Here the different secondary crater populations formed by the Hokusai crater on Mercury are systematically studied, and they are compared with those on the Moon to investigate their contribution to the evolution of local crater populations. Self-secondaries cause equilibrium on continuous ejecta deposits in a short time, and the equilibrium crater population has a differential size-frequency distribution (SFD) slope of about -3. Background secondaries are abundant on Mercury, and equilibrium caused by a combination of primaries and potential background secondaries follows the same pattern on the Moon and Mercury. The spatial dispersion of fragments that form both near-field and distant secondaries is the major factor affecting the degree of mutual destruction and thus the final crater SFD. Some clustered distant secondaries on Mercury are likely formed by individual fragments considering their large spatial dispersion and identical morphology with same-sized primaries, and the SFD rollovers of these secondaries possibly reflect the inherent SFD rollovers of the impact fragments. Near-field secondaries and many other distant secondaries have morphology and spatial distribution that are consistent with being formed by clustered fragments, and mutual destruction of secondaries may be the major reason causing the observed SFD rollovers. Heterogeneous secondary impacts are a potential explanation for both different crater densities within the equilibrium diameter range and different regolith thicknesses on coeval surfaces.

  19. Arrays of size and distance controlled platinum nanoparticles fabricated by a colloidal method

    Science.gov (United States)

    Manzke, Achim; Vogel, Nicolas; Weiss, Clemens K.; Ziener, Ulrich; Plettl, Alfred; Landfester, Katharina; Ziemann, Paul

    2011-06-01

    Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles. Subsequent application of plasma etching and annealing steps allows complete removal of the PS carriers and in parallel nucleation and growth of Pt nanoparticles (NPs) which are located at the original center of the PS colloids. In this way, hexagonally arranged spherical Pt NPs are obtained with controlled size and interparticle distances demonstrating variability and precision with so far unknown parameter scalability. This control is demonstrated by the fabrication of Pt NP arrays at a fixed particle distance of 185 nm while systematically varying the diameters between 8 and 15 nm. Further progress could be achieved by seeded emulsion polymerization. Here, Pt loaded PS colloids of 130 nm were used as seeds for a subsequent additional emulsion polymerization, systematically enlarging the diameter of the PS particles. Applying the plasma and annealing steps as above, in this way hexagonally ordered arrays of 9 nm Pt NPs could be obtained at distances up to 260 nm. To demonstrate their stability, such Pt particles were used as etching masks during reactive ion etching thereby transferring their hexagonal pattern into the Si substrate resulting in corresponding arrays of nanopillars.Based on emulsion polymerization in the presence of a Pt complex, polystyrene (PS) particles were prepared exhibiting a well defined average diameter with narrow size-distribution. Furthermore, the colloids contain a controlled concentration of the Pt precursor complex. Optimized coating of Si substrates with such colloids leads to extended areas of hexagonally ordered close-packed PS particles

  20. Sensitivity of direct climate forcing by atmospheric aerosols to aerosol size and composition

    Science.gov (United States)

    Pilinis, Christodoulos; Pandis, Spyros N.; Seinfeld, John H.

    1995-09-01

    We evaluate, using a box model, the sensitivity of direct climate forcing by atmospheric aerosols for a "global mean" aerosol that consists of fine and coarse modes to aerosol composition, aerosol size distribution, relative humidity (RH), aerosol mixing state (internal versus external mixture), deliquescence/crystallization hysteresis, and solar zenith angle. We also examine the dependence of aerosol upscatter fraction on aerosol size, solar zenith angle, and wavelength and the dependence of single scatter albedo on wavelength and aerosol composition. The single most important parameter in determining direct aerosol forcing is relative humidity, and the most important process is the increase of the aerosol mass as a result of water uptake. An increase of the relative humidity from 40 to 80% is estimated for the global mean aerosol considered to result in an increase of the radiative forcing by a factor of 2.1. Forcing is relatively insensitive to the fine mode diameter increase due to hygroscopic growth, as long as this mode remains inside the efficient scattering size region. The hysteresis/deliquescence region introduces additional uncertainty but, in general, errors less than 20% result by the use of the average of the two curves to predict forcing. For fine aerosol mode mean diameters in the 0.2-0.5 μm range direct aerosol forcing is relatively insensitive (errors less than 20%) to variations of the mean diameter. Estimation of the coarse mode diameter within a factor of 2 is generally sufficient for the estimation of the total aerosol radiative forcing within 20%. Moreover, the coarse mode, which represents the nonanthropogenic fraction of the aerosol, is estimated to contribute less than 10% of the total radiative forcing for all RHs of interest. Aerosol chemical composition is important to direct radiative forcing as it determines (1) water uptake with RH, and (2) optical properties. The effect of absorption by aerosol components on forcing is found to be

  1. Duodenal myotomy blocks reduction of meal size and prolongation of intermeal interval by cholecystokinin.

    Science.gov (United States)

    Lateef, Dalya M; Washington, Martha C; Raboin, Shannon J; Roberson, Allison E; Mansour, Mahmoud M; Williams, Carol S; Sayegh, Ayman I

    2012-02-01

    We have shown that vagotomy (VGX) attenuates the reduction of meal size (MS) produced by cholecystokinin (CCK) -8 and -33 and that celiaco-mesenteric ganglionectomy (CMGX) attenuates the prolongation of the intermeal interval (IMI) produced by CCK-33. Here, we report the following novel data. First, by determining the distribution of CCK(1) receptor messenger RNA, which mediates reduction of MS and prolongation of IMI by CCK, in seven regions of the gastrointestinal tract in the adult rat we found that the duodenum contains the highest concentration of this receptor in the gut. Second, based on the previous finding we performed a unique surgical technique known as duodenal myotomy (MYO), which severs all the nerves of the gut wall in the duodenum including vagus, splanchnic and enteric nerves. Third, we determined MS and IMI in duodenal MYO rats in responses to endogenous CCK-58 released by the non-nutrient, trypsin inhibitor, camostat and CCK-8 to test the possibility that the duodenum is the site of action for reduction of MS and prolongation of IMI. We found that, similar to the previous work reported by using CCK-8 and MS, duodenal MYO also blocked reduction of MS by camostat. Forth, duodenal MYO blocked prolongation of IMI by camostat. As such, our current results suggest that the duodenum is the gut site that communicates both feeding signals of endogenous CCK, MS and IMI, with the brain through vagal and splanchnic afferents.

  2. Optical extinction for determining the size distribution of gold nanoparticles fabricated by ultra-short pulsed laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Torchia, G.A. [Centro de Investigaciones Opticas (CIOp), La Plata (Argentina); Universidad de Salamanca, Servicio Laser, Salamanca (Spain); Scaffardi, L.B. [Centro de Investigaciones Opticas (CIOp), La Plata (Argentina); Universidad Nacional La Plata, Departamento de Ciencias Basicas, Facultad de Ingenieria, La Plata (Argentina); Mendez, C.; Moreno, P.; Roso, L. [Universidad de Salamanca, Servicio Laser, Salamanca (Spain); Tocho, J.O. [Centro de Investigaciones Opticas (CIOp), La Plata (Argentina); Universidad Nacional de La Plata, Departamento de Fisica, Facultad de Ciencias Exactas, La Plata (Argentina)

    2008-12-15

    This work presents a method, based on measurements of the optical extinction spectra, to determine the size of spherical gold nanoparticles produced using the femtosecond laser ablation process in deionized water. By using an improved theoretical model that modifies the contribution of the free electrons to the dielectric function introducing a size-dependent term, it is possible to fit the full experimental extinction spectrum considering a certain size distribution. Additionally, in order to obtain complementary measurements of the size distribution, TEM analysis was performed. The results obtained showed that the predominant nanoparticle size distribution ranges from 1 to 11 nm in terms of radii. An optical extinction measurement together with an appropriate theoretical model based on Mie's theory represents a simple, low-cost, fast and easy method to describe a multimodal size distribution of spherical gold nanoparticles. (orig.)

  3. SSZ-13 Crystallization by Particle Attachment and Deterministic Pathways to Crystal Size Control.

    Science.gov (United States)

    Kumar, Manjesh; Luo, Helen; Román-Leshkov, Yuriy; Rimer, Jeffrey D

    2015-10-14

    Many synthetic and natural crystalline materials are either known or postulated to grow via nonclassical pathways involving the initial self-assembly of precursors that serve as putative growth units for crystallization. Elucidating the pathway(s) by which precursors attach to crystal surfaces and structurally rearrange (postattachment) to incorporate into the underlying crystalline lattice is an active and expanding area of research comprising many unanswered fundamental questions. Here, we examine the crystallization of SSZ-13, which is an aluminosilicate zeolite that possesses exceptional physicochemical properties for applications in separations and catalysis (e.g., methanol upgrading to chemicals and the environmental remediation of NO(x)). We show that SSZ-13 grows by two concerted mechanisms: nonclassical growth involving the attachment of amorphous aluminosilicate particles to crystal surfaces and classical layer-by-layer growth via the incorporation of molecules to advancing steps on the crystal surface. A facile, commercially viable method of tailoring SSZ-13 crystal size and morphology is introduced wherein growth modifiers are used to mediate precursor aggregation and attachment to crystal surfaces. We demonstrate that small quantities of polymers can be used to tune crystal size over 3 orders of magnitude (0.1-20 μm), alter crystal shape, and introduce mesoporosity. Given the ubiquitous presence of amorphous precursors in a wide variety of microporous crystals, insight of the SSZ-13 growth mechanism may prove to be broadly applicable to other materials. Moreover, the ability to selectively tailor the physical properties of SSZ-13 crystals through molecular design offers new routes to optimize their performance in a wide range of commercial applications.

  4. Munc18-1 expression levels control synapse recovery by regulating readily releasable pool size

    Science.gov (United States)

    Toonen, Ruud F. G.; Wierda, Keimpe; Sons, Michèle S.; de Wit, Heidi; Cornelisse, L. Niels; Brussaard, Arjen; Plomp, Jaap J.; Verhage, Matthijs

    2006-01-01

    Prompt recovery after intense activity is an essential feature of most mammalian synapses. Here we show that synapses with reduced expression of the presynaptic gene munc18-1 suffer from increased depression during intense stimulation at glutamatergic, GABAergic, and neuromuscular synapses. Conversely, munc18-1 overexpression makes these synapses recover faster. Concomitant changes in the readily releasable vesicle pool and its refill kinetics were found. The number of vesicles docked at the active zone and the total number of vesicles per terminal correlated with both munc18-1 expression levels and the size of the releasable vesicle pool. These data show that varying expression of a single gene controls synaptic recovery by modulating the number of docked, release-ready vesicles and thereby replenishment of the secretion capacity. PMID:17110441

  5. Analyzing insulin samples by size-exclusion chromatography: a column degradation study.

    Science.gov (United States)

    Teska, Brandon M; Kumar, Amit; Carpenter, John F; Wempe, Michael F

    2015-04-01

    Investigating insulin analogs and probing their intrinsic stability at physiological temperature, we observed significant degradation in the size-exclusion chromatography (SEC) signal over a moderate number of insulin sample injections, which generated concerns about the quality of the separations. Therefore, our research goal was to identify the cause(s) for the observed signal degradation and attempt to mitigate the degradation in order to extend SEC column lifespan. In these studies, we used multiangle light scattering, nuclear magnetic resonance, and gas chromatography-mass spectrometry methods to evaluate column degradation. The results from these studies illustrate: (1) that zinc ions introduced by the insulin product produced the observed column performance issues; and (2) that including ethylenediaminetetraacetic acid, a zinc chelator, in the mobile phase helped to maintain column performance.

  6. Size of craters produced by explosive charges on or above the ground surface

    Science.gov (United States)

    Ambrosini, R. D.; Luccioni, B. M.; Danesi, R. F.; Riera, J. D.; Rocha, M. M.

    The results of a series of tests performed with different amounts of explosive at short distances above and below ground level, as well as on the soil surface are briefly described. After an introductory description of both the main features of the blast wave and the mechanics of crater formation, a brief review of empirical methods for crater size prediction is presented. Next, the experimental design and the results obtained are described. The crater dimensions for underground explosions coincide with those found in the literature. For explosions at ground level the results are qualitatively described by empirical equations. For explosive charges situated above ground level, the dimensions of the craters are smaller than those observed in underground and near the surface explosions. Two new single prediction equations for this case are presented.

  7. Determination of pore size distributions in capillary-channeled polymer fiber stationary phases by inverse size-exclusion chromatography and implications for fast protein separations.

    Science.gov (United States)

    Wang, Zhengxin; Marcus, R Kenneth

    2014-07-18

    Capillary-channeled polymer (C-CP) fibers have been utilized as liquid chromatography stationary phases, primarily for biomacromolecule separations on the analytical and preparative scales. The collinear packing of the eight-channeled C-CP fibers provides for very efficient flow, allowing operation at high linear velocity (u>100mm s(-1)) and low backpressure (transport properties, there must not be mass transfer limitations as would be imposed by having an appreciably porous phase, wherein solute diffusion limits the overall mass transport rates. To better understand the physical nano-/micro- structure of C-CP fibers, inverse size exclusion chromatography (iSEC) has been employed to determine the pore size distribution (PSD) within C-CP fibers. A diversity of test species (from metal ions to large proteins) was used as probes under non-retaining conditions to obtain a response curve reflecting the apparent partition coefficient (Kd) versus hydrodynamic radii (rm). A mean pore radius (rp) of 4.2nm with standard deviation (sp) of ±1.1nm was calculated by fitting the Kd versus rm data to model equations with a Gaussian pore size distribution, and a pore radius of 4.0±0.1nm was calculated based on a log-normal distribution. The derived mean pore radius is much smaller than traditional support materials, with the standard deviation showing a relatively uniform pore distribution. van Deemter plots were analyzed to provide practical confirmation of the structural implications. Large molecules (e.g., proteins) that are fully excluded from pores have no significant C-terms in the van Deemter plots whereas small molecules that can access the pore volumes display appreciable C-terms, as expected. Fitting of retention data to the Knox equation suggests that the columns operate with a characteristic particle diameter (dp) of ∼53μm.

  8. Pellet-free isolation of human and bovine milk extracellular vesicles by size-exclusion chromatography

    Science.gov (United States)

    Blans, Kristine; Hansen, Maria S.; Sørensen, Laila V.; Hvam, Michael L.; Howard, Kenneth A.; Möller, Arne; Wiking, Lars; Larsen, Lotte B.; Rasmussen, Jan T.

    2017-01-01

    ABSTRACT Studies have suggested that nanoscale extracellular vesicles (EV) in human and bovine milk carry immune modulatory properties which could provide beneficial health effects to infants. In order to assess the possible health effects of milk EV, it is essential to use isolates of high purity from other more abundant milk structures with well-documented bioactive properties. Furthermore, gentle isolation procedures are important for reducing the risk of generating vesicle artefacts, particularly when EV subpopulations are investigated. In this study, we present two isolation approaches accomplished in three steps based on size-exclusion chromatography (SEC) resulting in effective and reproducible EV isolation from raw milk. The approaches do not require any EV pelleting and can be applied to both human and bovine milk. We show that SEC effectively separates phospholipid membrane vesicles from the primary casein and whey protein components in two differently obtained casein reduced milk fractions, with one of the fractions obtained without the use of ultracentrifugation. Milk EV isolates were enriched in lactadherin, CD9, CD63 and CD81 compared to minimal levels of the EV-marker proteins in other relevant milk fractions such as milk fat globules. Nanoparticle tracking analysis and electron microscopy reveals the presence of heterogeneous sized vesicle structures in milk EV isolates. Lipid analysis by thin layer chromatography shows that EV isolates are devoid of triacylglycerides and presents a phospholipid profile differing from milk fat globules surrounded by epithelial cell plasma membrane. Moreover, the milk EV fractions are enriched in RNA with distinct and diverging profiles from milk fat globules. Collectively, our data supports that successful milk EV isolation can be accomplished in few steps without the use of ultracentrifugation, as the presented isolation approaches based on SEC effectively isolates EV in both human and bovine milk. PMID:28386391

  9. Interrill erosion, runoff and sediment size distribution as affected by slope steepness and antecedent moisture content

    Directory of Open Access Journals (Sweden)

    M. B. Defersha

    2010-08-01

    Full Text Available Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by erosive agents such as flowing water. The rate at which erosion occurs depends upon the individual as well as interactive effects of different parameters responsible for soil erosion. The study discusses results of a laboratory analysis and evaluates the effect of slope steepness and antecedent moisture content on sediment yield (wash and runoff rate. Interrill sediment yield, splash detachment, runoff, and sediment size distribution were measured in laboratory erosion pans under simulated total duration of 90 min. Rainfall intensity at 120 mm/hr, 70 mm/hr, and 55 mm/hr were applied sequentially at 9, 25, and 45% slope steepness for three soils (Alemaya Black soil, Regosols, and Cambisols varied from clay to sandy clay loam in texture with wet and dry antecedent water contents. As slope steepness increased from 9 to 25% splash increased for five treatments and decreased for the remaining treatment; washed sediment increased for all treatments. As slope increased from 25 to 45% splash decreased for five treatments but increased for one treatment, and washed sediment increased for three treatments but decreased for the other three treatments. Pre-wetting decreased splash detachment for all soil treatments and rate of reduction was high for the highly aggregated soil, Alemaya Black soil and low for the less aggregated soil Regosols. Splash sediment and sediment yield was not correlated. Change in splash with increase in slope steepness was also not correlated with change in sediment yield. Change in runoff rate with increase in slope steepness was correlated (r=0.66 with change in sediment yield. For Alemaya Black soil and Regosols, splashed sediment size distribution was correlated with washed sediment size distribution. Interrill erosion models that include runoff and rainfall intensity parameters were a better fit for these data

  10. Ductility Enhancement of Molybdenum Phase by Nano-sized Oxide Dispersions

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Bruce

    2008-07-18

    The objective of this research is to understand and to remedy the impurity effects for room-temperature ductility enhancement of molybdenum (Mo) based alloys by the inclusion of nano-sized metal oxide dispersions. This research combines theoretical, computational, and experimental efforts. The results will help to formulate systematic strategies in searching for better composed Mo-based alloys with optimal mechanical properties. For this project, majority of the research effort was directed to atomistic modeling to identify the mechanisms responsible for the oxygen embrittling and ductility enhancement based on fundamental electronic structure analysis. Through first principles molecular dynamics simulations, it was found that the embrittling impurity species were attracted to the metal oxide interface, consistent with previous experiments. Further investigation on the electronic structures reveals that the presence of embrittling species degrades the quality of the metallic chemical bonds in the hosting matrix in a number of ways, the latter providing the source of ductility. For example, the spatial flexibility of the bonds is reduced, and localization of the impurity states occurs to pin the dislocation flow. Rice’s criterion has been invoked to explain the connections of electronic structure and mechanical properties. It was also found that when impurity species become attracted to the metal oxide interface, some of the detrimental effects are alleviated, thus explaining the observed ductility enhancement effects. These understandings help to develop predictive capabilities to facilitate the design and optimization of Mo and other high temperature alloys (e.g. ODS alloys) for fossil energy materials applications. Based on the theoretical and computational studies, the experimental work includes the preparation of Mo powders mixed with candidate nano-sized metal oxides, which were then vacuum hot-pressed to make the Mo alloys. Several powder mixing methods

  11. Can we gain precision by sampling with probabilities proportional to size in surveying recent landscape changes in the Netherlands?

    NARCIS (Netherlands)

    Brus, D.J.; Nieuwenhuizen, W.; Koomen, A.J.M.

    2006-01-01

    Seventy-two squares of 100 ha were selected by stratified random sampling with probabilities proportional to size (pps) to survey landscape changes in the period 1996-2003. The area of the plots times the urbanization pressure was used as a size measure. The central question of this study is whether

  12. How many walking and cycling trips made by elderly are beyond commonly used buffer sizes: Results from a GPS study

    NARCIS (Netherlands)

    Prins, R.G.; Pierik, F.; Etman, A.; Sterkenburg, R.P.; Kamphuis, C.B.M.; Lenthe, F.J. van

    2014-01-01

    In choosing appropriate buffer sizes to study environmental influences on physical activity, studies are hampered by insufficient insight into the distance elderly travel actively. This study aims at getting insight into the number of trips walked and cycled within various buffer sizes using GPS mea

  13. Ballistic-type field penetration into metals illustrated by high- and low-frequency size-effect measurements in silver

    DEFF Research Database (Denmark)

    Gantmakher, V. F.; Lebech, Jens; Bak, Christen Kjeldahl

    1979-01-01

    Radio-frequency size-effect experiments were performed on silver plane-parallel plates at high, 45 GHz, and low, 3 MHz, frequencies. By investigation of size-effect structures we show the influence of frequency on the field distribution inside the metal. When the frequency increases, the splash...

  14. Rise of dinosaurs reveals major body-size transitions are driven by passive processes of trait evolution.

    Science.gov (United States)

    Sookias, Roland B; Butler, Richard J; Benson, Roger B J

    2012-06-01

    A major macroevolutionary question concerns how long-term patterns of body-size evolution are underpinned by smaller scale processes along lineages. One outstanding long-term transition is the replacement of basal therapsids (stem-group mammals) by archosauromorphs, including dinosaurs, as the dominant large-bodied terrestrial fauna during the Triassic (approx. 252-201 million years ago). This landmark event preceded more than 150 million years of archosauromorph dominance. We analyse a new body-size dataset of more than 400 therapsid and archosauromorph species spanning the Late Permian-Middle Jurassic. Maximum-likelihood analyses indicate that Cope's rule (an active within-lineage trend of body-size increase) is extremely rare, despite conspicuous patterns of body-size turnover, and contrary to proposals that Cope's rule is central to vertebrate evolution. Instead, passive processes predominate in taxonomically and ecomorphologically more inclusive clades, with stasis common in less inclusive clades. Body-size limits are clade-dependent, suggesting intrinsic, biological factors are more important than the external environment. This clade-dependence is exemplified by maximum size of Middle-early Late Triassic archosauromorph predators exceeding that of contemporary herbivores, breaking a widely-accepted 'rule' that herbivore maximum size greatly exceeds carnivore maximum size. Archosauromorph and dinosaur dominance occurred via opportunistic replacement of therapsids following extinction, but were facilitated by higher archosauromorph growth rates.

  15. Sizes of main-belt asteroids by combining shape models and Keck adaptive aptics observations

    CERN Document Server

    Hanuš, J; Ďurech, J

    2013-01-01

    We select 50 main-belt asteroids with a diameter between 20 and 400 km for which we have (i) shape models derived by the lightcurve inversion method (LI) and (ii) resolved observations of good quality collected with the Keck II adaptive optics (AO) system in the near-infrared. We derive the size of these asteroids by minimizing the difference between the contours from deconvolved AO images and the projected silhouettes calculated from the shape model at the time of the AO observations. We compute the volume-equivalent diameters for 48 of these asteroids. For 15 of them, we remove the ambiguity of the pole orientation typical for shape models derived by the LI. We have found that our equivalent diameters are smaller by 3%, 7%, and 2% compared with the effective diameters derived from mid-IR photometric observations provided by IRAS, WISE and AKARI. For 40 asteroids with previously determined mass estimates, we compute their bulk densities and discuss the mass-density dependence with respect to taxonomic types.

  16. Size-dependent tuning of horseradish peroxidase bioreactivity by gold nanoparticles

    Science.gov (United States)

    Wu, Haohao; Liu, Yi; Li, Meng; Chong, Yu; Zeng, Mingyong; Lo, Y. Martin; Yin, Jun-Jie

    2015-02-01

    Molecules with diverse biological functions, such as heme peroxidases, can be useful tools for identifying potential biological effects of gold nanoparticles (AuNPs) at the molecular level. Here, using UV-Vis, circular dichroism, dynamic light scattering, and electron spin resonance spectroscopy, we report tuning of horseradish peroxidase (HRP) bioactivity by reactant-free AuNPs with diameters of 5, 10, 15, 30 and 60 nm (Au-5 nm, Au-10 nm, Au-15 nm, Au-30 nm and Au-60 nm). HRP conjugation to AuNPs was observed with only Au-5 nm and Au-10 nm prominently increasing the α-helicity of the enzyme to extents inversely related to their size. Au-5 nm inhibited both HRP peroxidase activity toward 3,3',5,5'-tetramethylbenzidine and HRP compound I/II reactivity toward 5,5-dimethyl-1-pyrroline N-oxide. Au-5 nm enhanced the HRP peroxidase activity toward ascorbic acid and the HRP compound I/II reactivity toward redox-active residues in the HRP protein moiety. Further, Au-5 nm also decreased the catalase- and oxidase-like activities of HRP. Au-10 nm showed similar, but weaker effects, while Au-15 nm, Au-30 nm and Au-60 nm had no effect. Results suggest that AuNPs can size-dependently enhance or inhibit HRP bioreactivity toward substrates with different redox potentials via a mechanism involving extension of the HRP substrate access channel and decline in the redox potentials of HRP catalytic intermediates.Molecules with diverse biological functions, such as heme peroxidases, can be useful tools for identifying potential biological effects of gold nanoparticles (AuNPs) at the molecular level. Here, using UV-Vis, circular dichroism, dynamic light scattering, and electron spin resonance spectroscopy, we report tuning of horseradish peroxidase (HRP) bioactivity by reactant-free AuNPs with diameters of 5, 10, 15, 30 and 60 nm (Au-5 nm, Au-10 nm, Au-15 nm, Au-30 nm and Au-60 nm). HRP conjugation to AuNPs was observed with only Au-5 nm and Au-10 nm prominently increasing the

  17. Variation in levels of reactive oxygen species is explained by maternal identity, sex and body-size-corrected clutch size in a lizard

    Science.gov (United States)

    Olsson, Mats; Wilson, Mark; Uller, Tobias; Mott, Beth; Isaksson, Caroline

    2009-01-01

    Many organisms show differences between males and females in growth rate and crucial life history parameters, such as longevity. Considering this, we may expect levels of toxic metabolic by-products of the respiratory chain, such as reactive oxygen species (ROS), to vary with age and sex. Here, we analyse ROS levels in female Australian painted dragon lizards ( Ctenophorus pictus) and their offspring using fluorescent probes and flow cytometry. Basal level of four ROS species (singlet oxygen, peroxynitrite, superoxide and H2O2) measured with a combined marker, and superoxide measured specifically, varied significantly among families but not between the sexes. When blood cells from offspring were chemically encouraged to accelerate the electron transport chain by mitochondrial uncoupling, net superoxide levels were three times higher in daughters than sons (resulting in levels outside of the normal ROS range) and varied among mothers depending on offspring sex (significant interaction between maternal identity and offspring sex). In offspring, there were depressive effects on ROS of size-controlled relative clutch size, which relies directly on circulating levels of vitellogenin, a confirmed antioxidant in some species. Thus, levels of reactive oxygen species varies among females, offspring and in relation to reproductive investment in a manner that makes its regulatory processes likely targets of selection.

  18. Analysis of submicron-sized niflumic acid crystals prepared by electrospray crystallization

    NARCIS (Netherlands)

    Ambrus, R.; Radacsi, N.; Szunyogh, T.; Heijden, A.E.D.M. van der; Horst, J.H. ter; Szabó-Révész, P.

    2013-01-01

    Interest in submicron-sized drug particles has emerged from both laboratory and industrial perspectives in the last decade. Production of crystals in the nano size scale offers a novel way to particles for drug formulation solving formulation problems of drugs with low solubility in class II of the

  19. A quantitative test of the size efficiency hypothesis by means of a physiologically structured model

    NARCIS (Netherlands)

    Hülsmann, S.; Rinke, K.; Mooij, W.M.

    2005-01-01

    According to the size-efficiency hypothesis (SEH) larger bodied cladocerans are better competitors for food than small bodied species. In environments with fish, however, the higher losses of the large bodied species due to size-selective predation may shift the balance in favor of the small bodied

  20. Genome Sizes of Nine Insect Species Determined by Flow Cytometry and k-mer Analysis

    Science.gov (United States)

    He, Kang; Lin, Kejian; Wang, Guirong; Li, Fei

    2016-01-01

    The flow cytometry method was used to estimate the genome sizes of nine agriculturally important insects, including two coleopterans, five Hemipterans, and two hymenopterans. Among which, the coleopteran Lissorhoptrus oryzophilus (Kuschel) had the largest genome of 981 Mb. The average genome size was 504 Mb, suggesting that insects have a moderate-size genome. Compared with the insects in other orders, hymenopterans had small genomes, which were averagely about ~200 Mb. We found that the genome sizes of four insect species were different between male and female, showing the organismal complexity of insects. The largest difference occurred in the coconut leaf beetle Brontispa longissima (Gestro). The male coconut leaf beetle had a 111 Mb larger genome than females, which might be due to the chromosome number difference between the sexes. The results indicated that insect invasiveness was not related to genome size. We also determined the genome sizes of the small brown planthopper Laodelphax striatellus (Fallén) and the parasitic wasp Macrocentrus cingulum (Brischke) using k-mer analysis with Illunima Solexa sequencing data. There were slight differences in the results from the two methods. k-mer analysis indicated that the genome size of L. striatellus was 500–700 Mb and that of M. cingulum was ~150 Mb. In all, the genome sizes information presented here should be helpful for designing the genome sequencing strategy when necessary. PMID:27932995

  1. Effect of sodium citrate on preparation of nano-sized cobalt particles by organic colloidal process

    Institute of Scientific and Technical Information of China (English)

    Huaping ZHU; Hao LI; Huiyu SONG; Shijun LIAO

    2009-01-01

    Nano-sized cobalt particles with the diameter of 2 nm were prepared via an organic colloidal process with sodium formate, ethylene glycol and sodium citrate as the reducing agent, the solvent and the complexing agent, respectively. The effects of sodium citrate on the yield, crystal structure, particle size and size distribution of the prepared nano-sized cobalt particles were then investigated. The results show that the average particle diameter decreases from 200 nm to 2 nm when the molar ratio of sodium citrate to cobalt chloride changes from 0 to 6. Furthermore, sodium citrate plays a crucial role in the controlling of size distribution of the nano-sized particles. The size distribution of the particle without sodium citrate addition is in range from tens of nanometers to 300 or 400 nm, while that with sodium citrate addition is limited in the range of (2±0.25) nm. Moreover, it is found that the addition of sodium citrate as a complex agent could decrease the yield of the nano-sized cobalt particle.

  2. Proprieties of quantitative evaluation of defect size by myocardial SPECT. Evaluation using myocardial phantom

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Jiro; Nakatsuka, Teruo; Fujioka, Tadao; Kashima, Kenji; Matsumura, Yasushi; Yamamoto, Kazuhiro

    1987-09-01

    The accuracy to quantify the size and the extent of Thallium-201 (Tl) uptake of defect zone by Tl single photon emission computed tomogram (SPECT) was evaluated, using myocardial phantom. Long-axis SPECT image was devided into 6 slices from apex to base, and radians were projected from the center to define 32 myocardial secters, 11.25 degrees each. Then the maximum count in each secter was plotted on each radian (maximum count circumferential profile analysis:mcCPA), and was normalized to the maximum count for the whole heart (%Tl-uptake). In this way, circumferential profile curve was obtained, and normal value in each secter of myocardial phantom with defects was analysed and the ratio of segments, %Tl-uptake of which was below the normal value, was defined as % defect volume (%DV). The difference between the value of %Tl-uptake of defect zone and the normal value was difined as defect severity, and the average of defect severity was defined as mean defect severity (mDS). We prepared myocardial phantoms with a variety of area of defect, and with a variety of thickness of defect, and acquired these SPECT images. %DV and mDS were calculated from those images and compared with real area and thickess of defect. In the phantom with given thickness of defect, %DV was closely correlated to area of defect (r > 0.976), but also correlated to thickness of defect. In the phantom with given area of defect, mDS was closely correlated to thickness of defect (r = 0.988), and also correlated to area of defect. In conclusion, %DV and mDS were good indices of the defect size and the extent of Tl-uptake respectively, but it is necessary to consider their influence on each other.

  3. An experimental study of asphaltene particle sizes in n-heptane-toluene mixtures by light scattering

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopal, K.; Silva, S.M.C. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Escola de Engenharia. Dept. de Engenharia Quimica]. E-mail: raja@eq.ufrj.br

    2004-12-01

    The particle size of asphaltene flocculates has been the subject of many recent studies because of its importance in the control of deposition in petroleum production and processing. We measured the size of asphaltene flocculates in toluene and toluene - n-heptane mixtures, using the light-scattering technique. The asphaltenes had been extracted from Brazilian oil from the Campos Basin, according to British Standards Method IP-143/82. The asphaltene concentration in solution ranged between 10{sup -6} g/ml and 10{sup -7} g/ml. Sizes was measured for a period of about 10000 minutes at a constant temperature of 20 deg C. We found that the average size of the particles remained constant with time and increase with an increase in amount of n-heptane. The correlation obtained for size with concentration will be useful in asphaltene precipitation models. (author)

  4. Determination of phytate in high molecular weight, charged organic matrices by two-dimensional size exclusion-ion chromatography

    Science.gov (United States)

    A two-dimensional chromatography method for analyzing anionic targets (specifically phytate) in complex matrices is described. Prior to quantification by anion exchange chromatography, the sample matrix was prepared by size exclusion chromatography, which removed the majority of matrix complexities....

  5. Exploring Size.

    Science.gov (United States)

    Brand, Judith, Ed.

    1995-01-01

    "Exploring" is a magazine of science, art, and human perception that communicates ideas museum exhibits cannot demonstrate easily by using experiments and activities for the classroom. This issue concentrates on size, examining it from a variety of viewpoints. The focus allows students to investigate and discuss interconnections among…

  6. Energy conserved and costs saved by small and medium-size manufacturers, 1988--1989

    Energy Technology Data Exchange (ETDEWEB)

    Kirsch, F.W.

    1991-05-01

    Energy Analysis and Diagnostic Centers (EADCs) provided energy-conserving and cost saving assistance in 339 small and medium-size manufacturing plants nationwide during 1988-89. This report presents the results of what was recommended to those manufacturers, the record of what was implemented by them, and an analysis of the financial rewards gained by them. It also includes an accounting of the financial returns to the federal government, derived from taxes upon the cost savings, or incremental income, of the manufacturers who implement the EADCs` recommendations. EADCs collect implementation data within a year of the energy audit, and for these results that time period extended through 1990. The EADCs are located at accredited engineering departments of universities and staffed by faculty and students. At present there are 18 EADCs serving manufacturers in 37 states; of these, two were established as a result of the 1989 competition, and five more were chosen competitively in 1990. Most of the results in this report were generated by 11 EADCs (named in the Appendix); two others withdrew voluntarily after completing only 10 energy audits during 1988-89. Primary responsibility for selecting, training, evaluating, and managing the EADCs belongs to the Industrial Technology and Energy Management (ITEM) division of University City Science Center (UCSC). The Department of Energy`s Office of Industrial Technologies sponsors the EADC program through an agreement with UCSC.

  7. Aneuploidogenic effects and DNA oxidation induced in vitro by differently sized gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Di Bucchianico S

    2014-05-01

    Full Text Available Sebastiano Di Bucchianico,1 Maria Rita Fabbrizi,1 Silvia Cirillo,1 Chiara Uboldi,1 Douglas Gilliland,2 Eugenia Valsami-Jones,3,4 Lucia Migliore11Department of Translational Research and New Technologies in Medicine and Surgery, Medical Genetics Unit, University of Pisa, Pisa, Italy; 2European Commission-Joint Research Centre, Institute for Health and Consumer Protection, NanoBioSciences Unit, Ispra, Italy; 3School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK; 4Earth Sciences, Natural History Museum, Cromwell Road, London, UKAbstract: Gold nanoparticles (Au NPs are used in many fields, including biomedical applications; however, no conclusive information on their potential cytotoxicity and genotoxicity mechanisms is available. For this reason, experiments in human primary lymphocytes and murine macrophages (Raw264.7 were performed exposing cells to spherical citrate-capped Au NPs with two different nominal diameters (5 nm and 15 nm. The proliferative activity, mitotic, apoptotic, and necrotic markers, as well as chromosomal damage were assessed by the cytokinesis-block micronucleus cytome assay. Fluorescence in situ hybridization with human and murine pancentromeric probes was applied to distinguish between clastogenic and aneuploidogenic effects. Our results indicate that 5 nm and 15 nm Au NPs are able to inhibit cell proliferation by apoptosis and to induce chromosomal damage, in particular chromosome mis-segregation. DNA strand breaks were detected by comet assay, and the modified protocol using endonuclease-III and formamidopyrimidine-DNA glycosylase restriction enzymes showed that pyrimidines and purines were oxidatively damaged by Au NPs. Moreover, we show a size-independent correlation between the cytotoxicity of Au NPs and their tested mass concentration or absolute number, and genotoxic effects which were more severe for Au NP 15 nm compared to Au NP 5 nm. Results indicate that

  8. Protein Corona Influences Cellular Uptake of Gold Nanoparticles by Phagocytic and Nonphagocytic Cells in a Size-Dependent Manner.

    Science.gov (United States)

    Cheng, Xiaju; Tian, Xin; Wu, Anqing; Li, Jianxiang; Tian, Jian; Chong, Yu; Chai, Zhifang; Zhao, Yuliang; Chen, Chunying; Ge, Cuicui

    2015-09-23

    The interaction at nanobio is a critical issue in designing safe nanomaterials for biomedical applications. Recent studies have reported that it is nanoparticle-protein corona rather than bare nanoparticle that determines the nanoparticle-cell interactions, including endocytic pathway and biological responses. Here, we demonstrate the effects of protein corona on cellular uptake of different sized gold nanoparticles in different cell lines. The experimental results show that protein corona significantly decreases the internalization of Au NPs in a particle size- and cell type-dependent manner. Protein corona exhibits much more significant inhibition on the uptake of large-sized Au NPs by phagocytic cell than that of small-sized Au NPs by nonphagocytic cell. The endocytosis experiment indicates that different endocytic pathways might be responsible for the differential roles of protein corona in the interaction of different sized Au NPs with different cell lines. Our findings can provide useful information for rational design of nanomaterials in biomedical application.

  9. Evaluation of city buses installed diesel particulate filter systems on fleet test; Diesel particulate filter system wo tosaishita rosen bus no soko chosa

    Energy Technology Data Exchange (ETDEWEB)

    Sudo, H. [Japan Automobile Research Institute Inc., Tsukuba (Japan)

    1997-10-01

    An environmental air quality of suspended particulate matter is insufficient in the big city area. To reduce the particulate matter, improvement of engine and development of the Diesel Particulate Filter (DPF) system are carrying. The purpose of this report is to investigate a possibility of practical use of the city buses installed DPF systems. From March 1995, investigation for practical use of these DPF systems on a route buses was carried in regular service operation of the Tokyo and Yokohama Transportation Bureau. The investigation items are service situation, smoke density and preparation inspection. From the result for 2 years service operation, each DPF systems needed some failure correspondence. but these were not fatal problem on using the DPF system. Then the subject of relative to durability and reliability became clear, and the performance of a low particulate emission DPF system obtained the high value evaluation for users. 9 refs., 4 figs., 2 tabs.

  10. Preliminary study on field buses for the control system of the high voltage of the ATLAS hadronic calorimeter; Etude preliminaire d`un reseau de terrain pour le systeme de controle des hautes tensions du calorimetre hadronique d`Atlas

    Energy Technology Data Exchange (ETDEWEB)

    Drevet, F.; Chadelas, R.; Montarou, G.

    1996-12-31

    We present here after a preliminary study on field buses for the control system of the high voltage of the photomultipliers of the TILECAL calorimeter. After some generalities, different commercial buses are reviewed (CAN, ARCET, WorldFIP, Profibus and LonWorks). The Profibus and LonWorks solution are more extensively studies as a possible solution for the high voltage system of the TILE hadronic calorimeter. (authors).

  11. Lateral inhibition-induced pattern formation controlled by the size and geometry of the cell.

    Science.gov (United States)

    Seirin Lee, Sungrim

    2016-09-01

    Pattern formation in development biology is one of the fundamental processes by which cells change their functions. It is based on the communication of cells via intra- and intercellular dynamics of biochemicals. Thus, the cell is directly involved in biochemical interactions. However, many theoretical approaches describing biochemical pattern formation have usually neglected the cell's role or have simplified the subcellular process without considering cellular aspects despite the cell being the environment where biochemicals interact. On the other hand, recent experimental observations suggest that a change in the physical conditions of cell-to-cell contact can result in a change in cell fate and tissue patterning in a lateral inhibition system. Here we develop a mathematical model by which biochemical dynamics can be directly observed with explicitly expressed cell structure and geometry in higher dimensions, and reconsider pattern formation by lateral inhibition of the Notch-Delta signaling pathway. We explore how the physical characteristic of cell, such as cell geometry or size, influences the biochemical pattern formation in a multi-cellular system. Our results suggest that a property based on cell geometry can be a novel mechanism for symmetry breaking inducing cell asymmetry. We show that cell volume can critically influence cell fate determination and pattern formation at the tissue level, and the surface area of the cell-to-cell contact can directly affect the spatial range of patterning.

  12. Dividing the pie: differential dung pat size utilization by sympatric Haematobia irritans and Musca autumnalis.

    Science.gov (United States)

    Fowler, F E; Mullens, B A

    2016-06-01

    Horn flies [Haematobia irritans (Diptera: Muscidae) (L.)] and face flies [Musca autumnalis (Diptera: Muscidae) De Geer] use the same larval resource, but their interactions are poorly studied. Dung pats (n = 350) were core sampled in the summers of 2012 and 2013 from irrigated pastures in Pomona, California, U.S.A. (34°03'N, 117°48'W) and held for face fly and horn fly emergence. Surface areas and estimated weights were recorded for each whole pat. Almost half (42.0%) of the pat cores yielded neither fly, 29.7% yielded horn flies only, 12.9% yielded face flies only and 15.4% yielded both flies. Of the fly-positive pats, surface area and mass were larger for face fly-occupied pats, whereas horn fly-occupied pats were smaller. Pats shared by the two species were intermediate. Horn flies per positive core were unaffected by the absence/presence of face flies, but half as many face flies emerged when pats were co-inhabited by horn flies. Face flies inhabited larger pats, which might better resist heating and drying, to which they are susceptible; horn flies inhabited a broad pat size range. Horn fly tolerance of lower dung moisture probably allows horn flies to colonize and survive in a wide range of pats in dry areas like southern California.

  13. Fundamental research on the size and velocity measurements of coal powder by trajectory imaging

    Institute of Scientific and Technical Information of China (English)

    Xue-cheng WU; Ying-chun WU; Cong-chang ZHANG; Guo-neng LI; Qun-xing HUANG; Ling-hong CHEN; Kun-zan QIU

    2013-01-01

    A trajectory imaging based method for measuring the velocity and diameter of coal particles was presented.By using an industrial charge-coupled device (CCD) camera and a low power semiconductor laser,the images of coal particles under relatively long exposure time were recorded and then processed to yield both the velocities and sizes.Fundamental research on this method with special attention to recording parameters,e.g.,magnification factor and exposure time,was carried out.For most of the test cases,the results agree with those obtained by particle image velocimetry (PIV) and shadow imaging method.Measurements with good accuracy can be obtained when the imaging magnification factor and exposure time are set appropriately,making N be larger than 3.5,and R between 5-7,where N and R are the number of pixels occupied by the average width and the ratio of length to width of particle trajectory on the image,respectively.The work indicates the feasibility and potential application of the present measurement method for online measurement of coal powder in pipes in industrial power plants.

  14. Aurora B suppresses microtubule dynamics and limits central spindle size by locally activating KIF4A

    Science.gov (United States)

    Nunes Bastos, Ricardo; Gandhi, Sapan R.; Baron, Ryan D.; Gruneberg, Ulrike; Nigg, Erich A.

    2013-01-01

    Anaphase central spindle formation is controlled by the microtubule-stabilizing factor PRC1 and the kinesin KIF4A. We show that an MKlp2-dependent pool of Aurora B at the central spindle, rather than global Aurora B activity, regulates KIF4A accumulation at the central spindle. KIF4A phosphorylation by Aurora B stimulates the maximal microtubule-dependent ATPase activity of KIF4A and promotes its interaction with PRC1. In the presence of phosphorylated KIF4A, microtubules grew more slowly and showed long pauses in growth, resulting in the generation of shorter PRC1-stabilized microtubule overlaps in vitro. Cells expressing only mutant forms of KIF4A lacking the Aurora B phosphorylation site overextended the anaphase central spindle, demonstrating that this regulation is crucial for microtubule length control in vivo. Aurora B therefore ensures that suppression of microtubule dynamic instability by KIF4A is restricted to a specific subset of microtubules and thereby contributes to central spindle size control in anaphase. PMID:23940115

  15. Enhanced crystal grain size by bromine doping in electrodeposited Cu{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Han Kunhee; Kang Feng [Department of Electrical Engineering, University of Texas at Arlington, Arlington, TX 76019 (United States); Han Xiaofei [Department of Material Science and Engineering, University of Texas at Arlington, Arlington, TX 76019 (United States); Tao Meng, E-mail: meng.tao@asu.edu [Department of Electrical Engineering, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2012-06-01

    Extremely large crystal grains are obtained by bromine doping in electrodeposited Cu{sub 2}O on indium tin oxide (ITO) substrate through an acetate bath. The grains are as large as 10,000 {mu}m{sup 2} in area, or {approx} 100 {mu}m in linear dimension, while the film is only 1-5 {mu}m thick. The enhanced grain size is explained by the effect of over-potential for the Cu{sup 2+}/Cu{sup +} redox couple on nucleation density of Cu{sub 2}O on ITO substrate. The over-potential is a function of several deposition conditions including solution pH, deposition potential, deposition temperature, bromine precursor concentration, and copper precursor concentration. In addition, undoped Cu{sub 2}O displays a high resistivity of 100 M{Omega}cm. Bromine doping in Cu{sub 2}O significantly reduces the resistivity to as low as 42 {Omega}cm after vacuum annealing. Br-doped Cu{sub 2}O shows n-type behavior. - Highlights: Black-Right-Pointing-Pointer Extremely large crystal grains ({approx} 100 {mu}m) achieved in electrodeposited Br-doped Cu{sub 2}O. Black-Right-Pointing-Pointer Large grains reduce carrier recombination and carrier scattering at grain boundaries. Black-Right-Pointing-Pointer N-type behavior demonstrated in naturally p-type Cu{sub 2}O by Br doping.

  16. Tuning surface reactivity by finite size effects: role of orbital symmetry in the d - band model

    Science.gov (United States)

    Snijders, Paul; Yin, Xiangshi; Cooper, Valentino; Weitering, Hanno

    Catalytic activity depends sensitively on the strength of the interactions between reactant molecules and catalyst surface: too weak and the catalyst cannot capture enough molecules to react; too strong and the reaction products do not desorb, blocking further reactions. The ability to control the binding strength of molecules to metal surfaces is thus fundamental to the design of efficient and selective catalysts. Catalyst design often relies on increasing the interaction strength on relatively non-reactive materials by introducing active sites. Here, we present a complementary approach: we exploit finite size effects in the electronic structure of ultrathin Pd(111) films grown on Ru(0001) to tune their reactivity by changing the film thickness one atom layer at a time. While bulk Pd(111) is reactive toward oxygen, we find that Pd films thinner than 6 atom layers are surprisingly inert to oxidation. This observation can be explained with the d-band model only when it is applied to the orbitals directly involved in the bonding. The insight into orbital specific contributions to surface reactivity could be useful in the design of catalysts. This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  17. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size

    Directory of Open Access Journals (Sweden)

    Yazan Haddad

    2016-04-01

    Full Text Available Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated, MAN127 (polyvinylpyrrolidone-coated, MAN158 (phosphate-coated, and MAN164 (tripolyphosphate-coated. All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration. A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  18. The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

    Science.gov (United States)

    Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

    2016-04-20

    Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

  19. Germanium Sub-Microspheres Synthesized by Picosecond Pulsed Laser Melting in Liquids: Educt Size Effects

    Science.gov (United States)

    Zhang, Dongshi; Lau, Marcus; Lu, Suwei; Barcikowski, Stephan; Gökce, Bilal

    2017-01-01

    Pulsed laser melting in liquid (PLML) has emerged as a facile approach to synthesize submicron spheres (SMSs) for various applications. Typically lasers with long pulse durations in the nanosecond regime are used. However, recent findings show that during melting the energy absorbed by the particle will be dissipated promptly after laser-matter interaction following the temperature decrease within tens of nanoseconds and hence limiting the efficiency of longer pulse widths. Here, the feasibility to utilize a picosecond laser to synthesize Ge SMSs (200~1000 nm in diameter) is demonstrated by irradiating polydisperse Ge powders in water and isopropanol. Through analyzing the educt size dependent SMSs formation mechanism, we find that Ge powders (200~1000 nm) are directly transformed into SMSs during PLML via reshaping, while comparatively larger powders (1000~2000 nm) are split into daughter SMSs via liquid droplet bisection. Furthermore, the contribution of powders larger than 2000 nm and smaller than 200 nm to form SMSs is discussed. This work shows that compared to nanosecond lasers, picosecond lasers are also suitable to produce SMSs if the pulse duration is longer than the material electron-phonon coupling period to allow thermal relaxation.

  20. Damage localization in a residential-sized wind turbine blade by use of the SDDLV method

    Science.gov (United States)

    Johansen, R. J.; Hansen, L. M.; Ulriksen, M. D.; Tcherniak, D.; Damkilde, L.

    2015-07-01

    The stochastic dynamic damage location vector (SDDLV) method has previously proved to facilitate effective damage localization in truss- and plate-like structures. The method is based on interrogating damage-induced changes in transfer function matrices in cases where these matrices cannot be derived explicitly due to unknown input. Instead, vectors from the kernel of the transfer function matrix change are utilized; vectors which are derived on the basis of the system and state-to-output mapping matrices from output-only state-space realizations. The idea is then to convert the kernel vectors associated with the lowest singular values into static pseudo-loads and apply these alternately to an undamaged reference model with known stiffness matrix. By doing so, the stresses in the potentially damaged elements will, theoretically, approach zero. The present paper demonstrates an application of the SDDLV method for localization of structural damages in a cantilevered residential-sized wind turbine blade. The blade was excited by an unmeasured multi-impulse load and the resulting dynamic response was captured through accelerometers mounted along the blade. The static pseudo-loads were applied to a finite element (FE) blade model, which was tuned against the modal parameters of the actual blade. In the experiments, an undamaged blade configuration was analysed along with different damage scenarios, hereby testing the applicability of the SDDLV method.

  1. Improving prediction of hydraulic conductivity by constraining capillary bundle models to a maximum pore size

    Science.gov (United States)

    Iden, Sascha C.; Peters, Andre; Durner, Wolfgang

    2015-11-01

    The prediction of unsaturated hydraulic conductivity from the soil water retention curve by pore-bundle models is a cost-effective and widely applied technique. One problem for conductivity predictions from retention functions with continuous derivatives, i.e. continuous water capacity functions, is that the hydraulic conductivity curve exhibits a sharp drop close to water saturation if the pore-size distribution is wide. So far this artifact has been ignored or removed by introducing an explicit air-entry value into the capillary saturation function. However, this correction leads to a retention function which is not continuously differentiable. We present a new parameterization of the hydraulic properties which uses the original saturation function (e.g. of van Genuchten) and introduces a maximum pore radius only in the pore-bundle model. In contrast to models using an explicit air entry, the resulting conductivity function is smooth and increases monotonically close to saturation. The model concept can easily be applied to any combination of retention curve and pore-bundle model. We derive closed-form expressions for the unimodal and multimodal van Genuchten-Mualem models and apply the model concept to curve fitting and inverse modeling of a transient outflow experiment. Since the new model retains the smoothness and continuous differentiability of the retention model and eliminates the sharp drop in conductivity close to saturation, the resulting hydraulic functions are physically more reasonable and ideal for numerical simulations with the Richards equation or multiphase flow models.

  2. Analysis of differently sized prototypes of an MR clutch by performance indices

    Science.gov (United States)

    Bucchi, Francesco; Forte, Paola; Franceschini, Alessandro; Frendo, Francesco

    2013-10-01

    In this paper we investigate the torque performances of three prototypes of a magnetorheological clutch, whose operation is based on the relative movement of a permanent magnet with respect to a gap filled with magnetorheological fluid, are discussed. The clutch was already been presented by the authors in other papers. The analysed prototypes are based on the same layout and have different sizes (i.e. outer diameter and overall length). Two new performance indices are introduced to evaluate the clutch design, and are proposed as an alternative to the usually employed turn-up ratio for evaluating MR clutches and brakes. Measurements of the transmitted torque in different operating conditions were carried out on a purpose-built test bench. A brushless motor drove the primary shaft of the clutch, while the transmitted torque was measured by a torque-meters up to 1500 rpm. The experimental results are discussed and compared to those expected on the basis of simulations, showing a fairly good agreement. Some geometric parameters were found to have a great influence on the magnet shielding in the disengaged configuration.

  3. Estimation of gear tooth transverse crack size from vibration by fusing selected gear condition indices

    Science.gov (United States)

    Choi, Sukhwan; Li, C. James

    2006-09-01

    Gears are common power transmission elements and are frequently responsible for transmission failures. Since a tooth crack is not directly measurable while a gear is in operation, one has to develop an indirect method to estimate its size from some measurables. This study developed such a method to estimate the size of a tooth transverse crack for a spur gear in operation. Using gear vibrations measured from an actual gear accelerated test, this study examined existing gear condition indices to identify those correlated well to crack size and established their utility for crack size estimation through index fusion using a neural network. When tested with vibrations measured from another accelerated test, the method had an averaged estimation error of about 5%.

  4. Evaluating grain size in polycrystals with rough surfaces by corrected ultrasonic attenuation.

    Science.gov (United States)

    Li, Xiongbing; Han, Xiaoqin; Arguelles, Andrea P; Song, Yongfeng; Hu, Hongwei

    2017-02-27

    Surface roughness of a sample has a great effect on the calculated grain size when measurements are based on ultrasonic attenuation. Combining modified transmission and reflection coefficients at the rough interface with a Multi-Gaussian beam model of the transducer, a comprehensive correction scheme for the attenuation coefficient is developed. An approximate inverse model of the calculated attenuation, based on Weaver's diffuse scattering theory, is established to evaluate grain size in polycrystals. The experimental results showed that for samples with varying surface roughness and matching microstructures, the fluctuation of evaluated average grain size was ±1.17μm. For polished samples with different microstructures, the relative errors to optical microscopy were no more than ±3.61%. The presented method provides an effective nondestructive tool for evaluating the grain size in metals with rough surfaces.

  5. Estimation of Pore Size Distribution by CO2 Adsorptionand Its Application in Physical Activation of Precursors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The CO2 adsorption data may show more than one section in theDubinin-Radushkevich-Kaganer(DRK) plot ifsamples had been over-activated. Each section in the plot represents arange of pore size.The whole DRK plot provided information on the pore size distribution(PSD)of a sample, which may be used to monitor the effect of activationconditions in activation processes.

  6. Tuning the crystal morphology and size of zeolitic imidazolate framework-8 in aqueous solution by surfactants

    KAUST Repository

    Pan, Yichang

    2011-01-01

    Herein we report a facile synthesis method using surfactant cetyltrimethylammonium bromide (CTAB) as a capping agent for controlling the crystal size and morphology of zeolitic imidazolate framework-8 (ZIF-8) crystals in aqueous systems. The particle sizes can be precisely adjusted from ca. 100 nm to 4 μm, and the morphology can be changed from truncated cubic to rhombic dodecahedron. This journal is © The Royal Society of Chemistry.

  7. Hydrodynamic discrimination of wakes caused by objects of different size or shape in a harbour seal (Phoca vitulina)

    DEFF Research Database (Denmark)

    Wieskotten, S.; Mauck, B.; Miersch, L.;

    2011-01-01

    that a seal may be using to do so. Hydrodynamic trails were generated by different sized or shaped paddles that were moved in the calm water of an experimental box to produce a characteristic signal. In a two-alternative forced-choice procedure the blindfolded subject was able to discriminate size differences...... to the arrangement of the vortices. We tested whether the seal used highest velocities, the steepness of the gradients and the spatial extension of the wake in a second set of experiments by varying moving speed and paddle size, respectively. The subject was still able to discriminate between the respective object...

  8. Effect of Elemental Powder Size on Foaming Behavior of NiTi Alloy Made by Combustion Synthesis

    Directory of Open Access Journals (Sweden)

    Naoyuki Kanetake

    2012-07-01

    Full Text Available Nickel titanium (NiTi foams were made by combustion synthesis of powders with the help of ZrH2 as foaming agent and TiB2 as endothermic agent. In this paper, we investigated the effect of elemental powder size on the foaming. The powder size of Ni and Ti affected the ignition temperature of the combustion reaction, cell morphology and microstructure of the foams. The cell morphology of the foams was also modified by the powder size of TiB2.

  9. Preparation and Characterization on Nano-Sized Barium Titanate Powder Doped with Lanthanum by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The nano-sized BaTiO3:La3+ powders were prepared by sol-gel process using butyl phthalate, barium acetate and lanthanum oxide as raw material, and these samples were tested by means of TG-DTA, XRD and SEM. The results indicate that with the annealing temperature and the doped concentration rising, the powders' particle sizes will increase and decrease respectively. When annealing temperature is 900 ℃ and doped concentration is 7%, the phase is cubic without other phases, and the particle size of power is 43.34 nm.

  10. Early life overnutrition induced by litter size manipulation decreases social play behavior in adolescent male rats.

    Science.gov (United States)

    Carvalho, Ana Laura O; Ferri, Bárbara G; de Sousa, Francielly A Lopes; Vilela, Fabiana C; Giusti-Paiva, Alexandre

    2016-10-01

    Several studies have investigated the effects of artificial litter size adjustment on offspring development. Social play behavior is important for neurobehavioral development and is impaired in several developmental psychiatric disorders. This study therefore investigated the effect of litter size on play behavior in adolescent rats. On postnatal day (PND) 2, litters were adjusted to a small litter (SL) size of 3 pups per dam or normal litter (NL) size of 12 pups per dam. Maternal behaviors scored daily during the first week of lactation (PND2-8) revealed that arched nursing and pup licking behaviors were increased in dams with SLs versus those with NLs. SL offspring exhibited accelerated weight gain and advanced development of physical landmarks and reflexes, possibly due to overnutrition. Social isolation lasting 3.5h prior to social play behavioral testing produced a higher frequency and duration of pouncing, pinning, sniffing, and grooming in both male and female offspring. However, male SL offspring exhibited a lower frequency of pouncing and pinning when compared with male NL offspring, while no litter size-dependent differences were observed in social behaviors unrelated to play (sniffing and grooming). These findings identify a possible sexually dimorphic influence of litter size in the development of social behavior. Given that social behaviors such as play behavior are vital for normal cognitive and social development, these findings have important implications for developmental and neuropsychiatric research.

  11. Long-term accounting for raindrop size distribution variations improves quantitative precipitation estimation by weather radar

    Science.gov (United States)

    Hazenberg, Pieter; Leijnse, Hidde; Uijlenhoet, Remko

    2016-04-01

    Weather radars provide information on the characteristics of precipitation at high spatial and temporal resolution. Unfortunately, rainfall measurements by radar are affected by multiple error sources. The current study is focused on the impact of variations of the raindrop size distribution on radar rainfall estimates. Such variations lead to errors in the estimated rainfall intensity (R) and specific attenuation (k) when using fixed relations for the conversion of the observed reflectivity (Z) into R and k. For non-polarimetric radar, this error source has received relatively little attention compared to other error sources. We propose to link the parameters of the Z-R and Z-k relations directly to those of the normalized gamma DSD. The benefit of this procedure is that it reduces the number of unknown parameters. In this work, the DSD parameters are obtained using 1) surface observations from a Parsivel and Thies LPM disdrometer, and 2) a Monte Carlo optimization procedure using surface rain gauge observations. The impact of both approaches for a given precipitation type is assessed for 45 days of summertime precipitation observed in The Netherlands. Accounting for DSD variations using disdrometer observations leads to an improved radar QPE product as compared to applying climatological Z-R and Z-k relations. This especially holds for situations where widespread stratiform precipitation is observed. The best results are obtained when the DSD parameters are optimized. However, the optimized Z-R and Z-k relations show an unrealistic variability that arises from uncorrected error sources. As such, the optimization approach does not result in a realistic DSD shape but instead also accounts for uncorrected error sources resulting in the best radar rainfall adjustment. Therefore, to further improve the quality of preciptitation estimates by weather radar, usage should either be made of polarimetric radar or by extending the network of disdrometers.

  12. Drop size effect on contact angle explained by nonextensive thermodynamics. Young's equation revisited.

    Science.gov (United States)

    Letellier, Pierre; Mayaffre, Alain; Turmine, Mireille

    2007-10-15

    We applied the concepts of nonextensive thermodynamics [Turmine et al., J. Phys. Chem. B 108 (2004) 18980], to describe the equilibrium of a liquid drop placed on a solid substrate. This approach provides a consistent formal framework for analyzing the contact angle according to the nature and structure of the substrate, and also the size of the drops. The introduction, for the solid/liquid interface, of the concept of "fuzzy interface" characterized by a thermodynamic dimension, different from 2/3 (surface) allowed description of the case of substrates with ill-defined geometry (such as porous, structured systems, fractal structure systems, etc.) and straightforward explanation of the phenomenon of super hydrophobicity without using a layer of trapped air in possible anfractuosities. The application of the nonextensive thermodynamics relationships, allowed explanation of all the usual behaviors described in the literature (Young, modified Young, Wenzel, Cassie-Baxter) including the case of the composite interfaces made of materials with different natures and spatial structures (smooth, rough, homogeneous and heterogeneous surfaces). We show that the contact angle can vary with the drop volume according to a power law, and this was validated against values published in the literature. This study also has consequences for the relations between "thermodynamic dimension" and "fractal dimension."

  13. Proliferation-independent regulation of organ size by Fgf/Notch signaling

    Science.gov (United States)

    Kozlovskaja-Gumbrienė, Agnė; Yi, Ren; Alexander, Richard; Aman, Andy; Jiskra, Ryan; Nagelberg, Danielle; Knaut, Holger; McClain, Melainia; Piotrowski, Tatjana

    2017-01-01

    Organ morphogenesis depends on the precise orchestration of cell migration, cell shape changes and cell adhesion. We demonstrate that Notch signaling is an integral part of the Wnt and Fgf signaling feedback loop coordinating cell migration and the self-organization of rosette-shaped sensory organs in the zebrafish lateral line system. We show that Notch signaling acts downstream of Fgf signaling to not only inhibit hair cell differentiation but also to induce and maintain stable epithelial rosettes. Ectopic Notch expression causes a significant increase in organ size independently of proliferation and the Hippo pathway. Transplantation and RNASeq analyses revealed that Notch signaling induces apical junctional complex genes that regulate cell adhesion and apical constriction. Our analysis also demonstrates that in the absence of patterning cues normally provided by a Wnt/Fgf signaling system, rosettes still self-organize in the presence of Notch signaling. DOI: http://dx.doi.org/10.7554/eLife.21049.001 PMID:28085667

  14. Particle size distribution of brown and white rice during gastric digestion measured by image analysis.

    Science.gov (United States)

    Bornhorst, Gail M; Kostlan, Kevin; Singh, R Paul

    2013-09-01

    The particle size distribution of foods during gastric digestion indicates the amount of physical breakdown that occurred due to the peristaltic movement of the stomach walls in addition to the breakdown that initially occurred during oral processing. The objective of this study was to present an image analysis technique that was rapid, simple, and could distinguish between food components (that is, rice kernel and bran layer in brown rice). The technique was used to quantify particle breakdown of brown and white rice during gastric digestion in growing pigs (used as a model for an adult human) over 480 min of digestion. The particle area distributions were fit to a Rosin-Rammler distribution function. Brown and white rice exhibited considerable breakdown as the number of particles per image decreased over time. The median particle area (x(50)) increased during digestion, suggesting a gastric sieving phenomenon, where small particles were emptied and larger particles were retained for additional breakdown. Brown rice breakdown was further quantified by an examination of the bran layer fragments and rice grain pieces. The percentage of total particle area composed of bran layer fragments was greater in the distal stomach than the proximal stomach in the first 120 min of digestion. The results of this study showed that image analysis may be used to quantify particle breakdown of a soft food product during gastric digestion, discriminate between different food components, and help to clarify the role of food structure and processing in food breakdown during gastric digestion.

  15. Size-selective recognition of catecholamines by molecular imprinting on silica-alumina gel.

    Science.gov (United States)

    Ling, Tzong-Rong; Syu, Yau Zen; Tasi, Yau-Ching; Chou, Tse-Chuan; Liu, Chung-Chiun

    2005-12-15

    The preparation of a catecholamine receptor was carried out using a molecular imprinting method with silica-alumina gel to form complementary structures for template recognition. The molecularly imprinted polymer (MIP) was synthesized by the condensation of silicate from tetraethyl orthosilictate (TEOS) under hydrothermal conditions at 60 degrees C. Aluminum chloride was added as a functional monomer to increase the material's rebinding ability. The selectivity of the MIP receptor prepared with different ratios of template to Si and Al, was examined with seven analytes including: dopamine, epinephrine, norepinephrine, ascorbic acid, homovanillic acid, uric acid, and l-tyrosine. The results showed a size selective effect for the receptors with respect to the recognition of the catecholamines. Some factors affecting the recognition ability were investigated including: the solution pH of analytes, surface capping on the MIP, and the imprinting pH of the silica-alumina solution. Also, the catecholamine MIP films on quartz crystal microbalance (QCM) electrodes were fabricated as sensors for in situ monitoring of the analytes in a 2-propanol solution.

  16. Particle sizing by dynamic light scattering: non-linear cumulant analysis.

    Science.gov (United States)

    Mailer, Alastair G; Clegg, Paul S; Pusey, Peter N

    2015-04-15

    We revisit the method of cumulants for analysing dynamic light scattering data in particle sizing applications. Here the data, in the form of the time correlation function of scattered light, is written as a series involving the first few cumulants (or moments) of the distribution of particle diffusion constants. Frisken (2001 Appl. Opt. 40 4087) has pointed out that, despite greater computational complexity, a non-linear, iterative, analysis of the data has advantages over the linear least-squares analysis used originally. In order to explore further the potential and limitations of cumulant methods we analyse, by both linear and non-linear methods, computer-generated data with realistic 'noise', where the parameters of the distribution can be set explicitly. We find that, with modern computers, non-linear analysis is straightforward and robust. The mean and variance of the distribution of diffusion constants can be obtained quite accurately for distributions of width (standard deviation/mean) up to about 0.6, but there appears to be little prospect of obtaining meaningful higher moments.

  17. Stroke Damage Is Exacerbated by Nano-Size Particulate Matter in a Mouse Model.

    Science.gov (United States)

    Liu, Qinghai; Babadjouni, Robin; Radwanski, Ryan; Cheng, Hank; Patel, Arati; Hodis, Drew M; He, Shuhan; Baumbacher, Peter; Russin, Jonathan J; Morgan, Todd E; Sioutas, Constantinos; Finch, Caleb E; Mack, William J

    2016-01-01

    This study examines the effects of nano-size particulate matter (nPM) exposure in the setting of murine reperfused stroke. Particulate matter is a potent source of inflammation and oxidative stress. These processes are known to influence stroke progression through recruitment of marginally viable penumbral tissue into the ischemic core. nPM was collected in an urban area in central Los Angeles, impacted primarily by traffic emissions. Re-aerosolized nPM or filtered air was then administered to mice through whole body exposure chambers for forty-five cumulative hours. Exposed mice then underwent middle cerebral artery occlusion/ reperfusion. Following cerebral ischemia/ reperfusion, mice exposed to nPM exhibited significantly larger infarct volumes and less favorable neurological deficit scores when compared to mice exposed to filtered air. Mice exposed to nPM also demonstrated increases in markers of inflammation and oxidative stress in the region of the ischemic core. The findings suggest a detrimental effect of urban airborne particulate matter exposure in the setting of acute ischemic stroke.

  18. Factors associated with the modulation of pain by visual distortion of body size.

    Directory of Open Access Journals (Sweden)

    Michihiro eOsumi

    2014-03-01

    Full Text Available Modulation of pain using visual distortion of body size (VDBS has been the subject of various reports. However, the mechanism underlying the effect of VDBS on pain has been less often studied. In the present study, factors associated with modulation of pain threshold by VDBS were investigated. Visual feedback in the form of a magnified image of the hand was provided to 44 healthy adults to examine changes in pain. In participants with a higher pain threshold when visual feedback of a magnified image of the hand was provided, the two-point discrimination threshold decreased. In contrast, participants with a lower pain threshold with visual feedback of a magnified image of the hand experienced unpleasant emotions toward the magnified image of the hand. Interestingly, this emotional reaction was strongly associated with negative body consciousness in several subjects. These data suggested an analgesic effect of visual feedback in the form of a magnified image of the hand is only when tactile perception is vivid and the emotional reaction toward the magnified image is moderate. The results also suggested that negative body consciousness is important for the modulation of pain using VDBS.

  19. Technological capability assessment of suppliers to support product development: case study on a buses and coaches manufacturer

    Directory of Open Access Journals (Sweden)

    Lucas Comerlato

    2013-05-01

    Full Text Available Supply chain management has become a critical issue in the global collaboration scenario. Suppliers are not expected to provide just commodities or pre-defined components, but also collaborative engineering design solutions within the product development cycle. Thus, the selection criteria for defining supply partner go beyond the production and logistic capabilities, but must also include technical and engineering competence. This, in some sense, can be considered a common scenario of big companies, but is still challenging when dealing with SME´s. This work discusses how SME´s can be included in a supply chains taking in consideration a set of parameters to assess their technical competence related to product development collaboration. A set of eight parameters has been proposed to assess the engineering team competence, physical and technological structure and further legal responsibility. For each parameter values and weights were defined also. The assessment was applied to three companies that are suppliers of a buses and coaches manufacturer from Rio Grande do Sul, Brazil. The results show that even when dealing with objective parameters, the suppliers and costumer can have different perceptions about same issues.

  20. Detection of thrombus size and protein content by ex vivo magnetization transfer and diffusion weighted MRI

    Directory of Open Access Journals (Sweden)

    Phinikaridou Alkystis

    2012-06-01

    Full Text Available Abstract Background To utilize a rabbit model of plaque disruption to assess the accuracy of different magnetic resonance sequences [T1-weighted (T1W, T2-weighted (T2W, magnetization transfer (MT and diffusion weighting (DW] at 11.7 T for the ex vivo detection of size and composition of thrombus associated with disrupted plaques. Methods Atherosclerosis was induced in the aorta of male New Zealand White rabbits (n = 17 by endothelial denudation and high-cholesterol diet. Subsequently, plaque disruption was induced by pharmacological triggering. Segments of infra-renal aorta were excised fixed in formalin and examined by ex vivo magnetic resonance imaging (MRI at 11.7 T and histology. Results MRI at 11.7 T showed that: (i magnetization transfer contrast (MTC and diffusion weighted images (DWI detected thrombus with higher sensitivity compared to T1W and T2W images [sensitivity: MTC = 88.2%, DWI = 76.5%, T1W = 66.6% and T2W = 43.7%, P P (ii MTC and DWI provided a more accurate detection of thrombus area with histology as the gold-standard [underestimation of 6% (MTC and 17.6% (DWI compared to an overestimation of thrombus area of 53.7% and 46.4% on T1W and T2W images, respectively]; (iii the percent magnetization transfer rate (MTR correlated with the fibrin (r = 0.73, P = 0.003 and collagen (r = 0.9, P = 0.004 content of the thrombus. Conclusions The conspicuity of the thrombus was increased on MTC and DW compared to T1W and T2W images. Changes in the %MTR and apparent diffusion coefficient can be used to identify the organization stage of the thrombus.

  1. Variation in seed size is structured by dispersal syndrome and cone morphology in conifers and other nonflowering seed plants.

    Science.gov (United States)

    Leslie, Andrew B; Beaulieu, Jeremy M; Mathews, Sarah

    2017-02-10

    Seed size varies tremendously in plants and its evolution is influenced by multiple ecological and biological factors that are difficult to disentangle. In this study, we focus on understanding the role of seed dispersal by animals in the evolution of seed size in conifers, the most diverse extant nonflowering seed plant group. Relationships among seed size, dispersal syndrome, climate and cone morphology were analyzed across conifers using quantitative models of character evolution and phylogenetic regression techniques. Dispersal syndrome is a more consistent predictor of seed size within major extant conifer clades than climate. Seeds are generally larger in animal-dispersed than wind-dispersed species, and particular cone morphologies are consistently associated with specific ranges in seed size. Seed size and cone morphology evolve in a correlated manner in many animal-dispersed conifers, following a trade-off that minimizes the total size of the dispersal unit. These relationships are also present in other nonflowering seed plant groups, and have been important in the evolution of seeds and cones at least over the Cenozoic and perhaps over much of the later Mesozoic.

  2. Preparation of protein-loaded microspheres with size ≤10 μm by electrostatic droplet generation technology

    Institute of Scientific and Technical Information of China (English)

    XUE Weiming; LIU Xiudong; YU Weiting; MA Xiaojun

    2006-01-01

    The development of non-injection route for protein drugs, especially oral administration, has been the main focus of controlled release of drugs. To overcome obstacles unsolved such as enzyme degradation and penetration barrier of intestinal epithelium, technologies using microspheres as carrier of protein drugs have been proven potential to realize oral administration. It has been demonstrated that microspheres can not only protect proteins, but also facilitate the penetration and absorption through Peyer's patches when the size is smaller than 10 μm. Therefore, the objective of this paper is to prepare protein-loaded microspheres with size ≤10 μm. Electrostatic droplet generation technology was used with insulin and hemoglobin as drug models and sodium alginate as microsphere material. By decreasing the surface tension of feed solution by adding surfactant, and improving electric field distribution by changing the shape of container and electrode for gelation solution, protein-loaded microspheres with mean size less than 10 μm were successfully produced through needle with diameter of 400 μm. The microspheres showed good sphericity and narrow size distribution. The mean standard variance of size distribution was 1.61. The encapsulation efficiency of proteins was over 70%. Moreover, the significance analysis of factors influencing the size of protein loaded microspheres was carried out through orthogonal experiments, which showed that output voltage (U), needle diameter (D) and the distance between needle tips to the surface of gelation solution (δ ) influenced significantly the size of microspheres. Finally, the statistic analysis showed that when confidence level wasα=0.05, and α=0.1, confidence interval of microsphere size can be (6.2545, 10.1735) and (6.6022, 9.8258) correspondingly, suggesting that there is good repeatability and reliability for improving electrostatic droplet generation technology to prepare protein-loaded microspheres with size

  3. Pore Size Effect on Methane Adsorption in Mesoporous Silica Materials Studied by Small-Angle Neutron Scattering.

    Science.gov (United States)

    Chiang, Wei-Shan; Fratini, Emiliano; Baglioni, Piero; Chen, Jin-Hong; Liu, Yun

    2016-09-06

    Methane adsorption in model mesoporous silica materials with the size range characteristic of shale is studied by small-angle neutron scattering (SANS). Size effect on the temperature-dependent gas adsorption at methane pressure about 100 kPa is investigated by SANS using MCM-41 and SBA-15 as adsorbents. Above the gas-liquid condensation temperature, the thickness of the adsorption layer is found to be roughly constant as a function of the temperature. Moreover, the gas adsorption properties, such as the adsorbed layer thickness and the specific amount of adsorbed gas, have little dependence on the pore size being studied, i.e., pore radius of 16.5 and 34.1 Å, but are mainly affected by the roughness of the pore surfaces. Hence, the surface properties of the pore wall are more dominant than the pore size in determining the methane gas adsorption of pores at the nanometer size range. Not surprisingly, the gas-liquid condensation temperature is observed to be sensitive to pore size and shifts to higher temperature when the pore size is smaller. Below the gas-liquid condensation temperature, even though the majority of gas adsorption experiments/simulations have assumed the density of confined liquid to be the same as the bulk density, the measured methane mass density in our samples is found to be appreciably smaller than the bulk methane density regardless of the pore sizes studied here. The mass density of liquid/solid methane in pores with different sizes shows different temperature dependence below the condensation temperature. With decreasing temperature, the methane density in larger pores (SBA-15) abruptly increases at approximately 65 K and then plateaus. In contrast, the density in smaller pores (MCM-41) monotonically increases with decreasing temperature before reaching a plateau at approximately 30 K.

  4. Summer Home Range Size and Habitat Use by River Otters in Ohio

    Directory of Open Access Journals (Sweden)

    David A. Helon

    2004-01-01

    Full Text Available Reintroduced river otters (Lontra canadensis are an important component of Ohio’s biological diversity, and are a key indicator of wetland and watershed health and quality. However, few data are available on their home range sizes and habitat use. We monitored river otters using radio-telemetry in the Killbuck Watershed, in northeastern Ohio, during 2002 and 2003 to determine home range and habitat use. Overall, mean home range size was 802.4 ha (range = 84.5–3,376.3, SE = 448.2 for female river otters and 1,101.7 ha (range = 713.8–1,502.6, SE = 102.2 for male river otters. Home range size of female and male river otters did not differ in 2002 (P = 0.763, but males had larger home range size than females during 2003 (P = 0.001. Based on compositional analysis, habitat use differed in proportion to availability of the 5 habitat types available in the study area (marsh, wet meadow, riparian/floodplain, open water, and flooded upland (P < 0.0001. Overall, river otters used marsh habitat with a diverse association of floating aquatics and emergent vegetation in greater proportion than was available. Knowledge and understanding of river otter habitat use and home range size in Ohio will help managers identify habitats suitable for river otters in the Midwestern United States.

  5. Size evolution in microorganisms masks trade-offs predicted by the growth rate hypothesis.

    Science.gov (United States)

    Gounand, Isabelle; Daufresne, Tanguy; Gravel, Dominique; Bouvier, Corinne; Bouvier, Thierry; Combe, Marine; Gougat-Barbera, Claire; Poly, Franck; Torres-Barceló, Clara; Mouquet, Nicolas

    2016-12-28

    Adaptation to local resource availability depends on responses in growth rate and nutrient acquisition. The growth rate hypothesis (GRH) suggests that growing fast should impair competitive abilities for phosphorus and nitrogen due to high demand for biosynthesis. However, in microorganisms, size influences both growth and uptake rates, which may mask trade-offs and instead generate a positive relationship between these traits (size hypothesis, SH). Here, we evolved a gradient of maximum growth rate (μmax) from a single bacterium ancestor to test the relationship among μmax, competitive ability for nutrients and cell size, while controlling for evolutionary history. We found a strong positive correlation between μmax and competitive ability for phosphorus, associated with a trade-off between μmax and cell size: strains selected for high μmax were smaller and better competitors for phosphorus. Our results strongly support the SH, while the trade-offs expected under GRH were not apparent. Beyond plasticity, unicellular populations can respond rapidly to selection pressure through joint evolution of their size and maximum growth rate. Our study stresses that physiological links between these traits tightly shape the evolution of competitive strategies.

  6. The Effective Use of Facebook by Small and Medium-Sized Enterprises Operating in Slovakia

    Directory of Open Access Journals (Sweden)

    František Pollák

    2016-06-01

    Full Text Available Purpose – The aim of this study was to identify and then interpret the basic preconditions for effective use of the social networking site Facebook as a marketing communication platform for small and medium-sized enterprises (SMEs operating in a selected Central European market. Design/Methodology/Approach – In order to achieve the objective, as well as partial targets, this contribution can be seen as a summary of two autonomous and extensive analyses. The context necessary for the fulfillment of the main objective was analyzed based on secondary data on hundreds of company profiles (of local SMEs, operating predominantly in the service sector and conducting their business activities in a business-to-consumer (B2C environment managed by a specific marketing agency operating on the Slovak market. The collected data were subsequently subjected to a thorough statistical testing based on monitored parameters. Findings and implications – From the perspective of the main findings, basic recommendations for the efficient use of selected marketing communication tools on the social networking site Facebook are described in terms of improving the expected user interactions. Limitations – We consider the mainly local nature of the data sources to be the biggest limitation in the research process. Due to the local nature of this study, however, this limitation has no significant effect on the quality of the research. Originality – The findings and information presented in this contribution can help improve our understanding of issues related to the effective implementation of resources (time and finances by entities using selected marketing tools, particularly marketing communication in the context of the social networking site Facebook for the purpose of promotion and branding.

  7. Size And Shape of Detergent Micelles Determined By Small-Angle X-Ray Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lipfert, Jan; Columbus, Linda; Chu, Vincent B.; Lesley, Scott A.; Doniach, Sebastian; /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept. /SLAC, SSRL /Pasteur Inst., Paris /Scripps Res. Inst. /Novartis Res. Found.

    2009-04-29

    We present a systematic analysis of the aggregation number and shape of micelles formed by nine detergents commonly used in the study of membrane proteins. Small-angle X-ray scattering measurements are reported for glucosides with 8 and 9 alkyl carbons (OG/NG), maltosides and phosphocholines with 10 and 12 alkyl carbons (DM/DDM and FC-10/FC-12), 1,2-dihexanoyl-sn-glycero-phosphocholine (DHPC), 1-palmitoyl-2-hydroxy-sn-glycero-3-[phospho-rac-(1-glycerol)] (LPPG), and 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonate (CHAPS). The SAXS intensities are well described by two-component ellipsoid models, with a dense outer shell corresponding to the detergent head groups and a less electron dense hydrophobic core. These models provide an intermediate resolution view of micelle size and shape. In addition, we show that Guinier analysis of the forward scattering intensity can be used to obtain an independent and model-free measurement of the micelle aggregation number and radius of gyration. This approach has the advantage of being easily generalizable to protein-detergent complexes, where simple geometric models are inapplicable. Furthermore, we have discovered that the position of the second maximum in the scattering intensity provides a direct measurement of the characteristic head group-head group spacing across the micelle core. Our results for the micellar aggregation numbers and dimensions agree favorably with literature values as far as they are available. We de novo determine the shape of FC-10, FC-12, DM, LPPG, and CHAPS micelles and the aggregation numbers of FC-10 and OG to be ca. 50 and 250, respectively. Combined, these data provide a comprehensive view of the determinants of micelle formation and serve as a starting point to correlate detergent properties with detergent-protein interactions.

  8. Landscape selection by piping plovers has implications for measuring habitat and population size

    Science.gov (United States)

    Anteau, Michael J.; Shaffer, Terry L.; Wiltermuth, Mark T.; Sherfy, Mark H.

    2014-01-01

    How breeding birds distribute in relation to landscape-scale habitat features has important implications for conservation because those features may constrain habitat suitability. Furthermore, knowledge of these associations can help build models to improve area-wide demographic estimates or to develop a sampling stratification for research and monitoring. This is particularly important for rare species that have uneven distributions across vast areas, such as the federally listed piping plover (Charadrius melodus; hereafter plover). We examined how remotely-sensed landscape features influenced the distribution of breeding plover pairs among 2-km shoreline segments during 2006–2009 at Lake Sakakawea in North Dakota, USA. We found strong associations between remotely-sensed landscape features and plover abundance and distribution (R2 = 0.65). Plovers were nearly absent from segments with bluffs (>25 m elevation increase within 250 m of shoreline). Relative plover density (pairs/ha) was markedly greater on islands (4.84 ± 1.22 SE) than on mainlands (0.85 ± 0.17 SE). Pair numbers increased with abundance of nesting habitat (unvegetated-flat areas β^=0.28±0.08SE ). On islands, pair numbers also increased with the relative proportion of the total area that was habitat ( β^=3.27±0.46SE ). Our model could be adapted to estimate the breeding population of plovers or to make predictions that provide a basis for stratification and design of future surveys. Knowledge of landscape features, such as bluffs, that exclude use by birds refines habitat suitability and facilitates more accurate estimates of habitat and population abundance, by decreasing the size of the sampling universe. Furthermore, techniques demonstrated here are applicable to other vast areas where birds breed in sparse or uneven densities.

  9. The cell size distribution of tomato fruit can be changed by overexpression of CDKA1.

    Science.gov (United States)

    Czerednik, Anna; Busscher, Marco; Angenent, Gerco C; de Maagd, Ruud A

    2015-02-01

    Tomato is one of the most cultivated vegetables in the world and an important ingredient of the human diet. Tomato breeders and growers face a continuous challenge of combining high quantity (production volume) with high quality (appearance, taste and perception for the consumers, processing quality for the processing industry). To improve the quality of tomato, it is important to understand the regulation of fruit development and of fruit cellular structure, which is in part determined by the sizes and numbers of cells within a tissue. The role of the cell cycle therein is poorly understood. Plant cyclin-dependent kinases (CDKs) are homologues of yeast cdc2, an important cell cycle regulator conserved throughout all eukaryotes. CDKA1 is constitutively expressed during the cell cycle and has dual functions in S- and M-phase progression. We have produced transgenic tomato plants with increased expression of CDKA1 under the control of the fruit-specific TPRP promoter, which despite a reduced number of seeds and diminished amount of jelly, developed fruits with weight and shape comparable to that of wild-type fruits. However, the phenotypic changes with regard to the pericarp thickness and placenta area were remarkable. Fruits of tomato plants with the highest expression of CDKA1 had larger septa and columella (placenta), compared with wild-type fruits. Our data demonstrate the possibility of manipulating the ratio between cell division and expansion by changing the expression of a key cell cycle regulator and probably its activity with substantial effects on structural traits of the harvested fruit.

  10. Orbit and size distributions for asteroids temporarily captured by the Earth-Moon system

    Science.gov (United States)

    Fedorets, Grigori; Granvik, Mikael; Jedicke, Robert

    2017-03-01

    As a continuation of the work by Granvik et al. (2012), we expand the statistical treatment of Earth's temporarily-captured natural satellites from temporarily-captured orbiters (TCOs, i.e., objects which make at least one orbit around the Earth) to the newly redefined subpopulation of temporarily-captured flybys (TCFs). TCFs are objects that while being gravitationally bound fail to make a complete orbit around the Earth while on a geocentric orbit, but nevertheless approach the Earth within its Hill radius. We follow the trajectories of massless test asteroids through the Earth-Moon system and record the orbital characteristics of those that are temporarily captured. We then carry out a steady-state analysis utilizing the novel NEO population model by Granvik et al. (2016). We also investigate how an quadratic distribution at very small values of e⊙ and i⊙ affects the predicted population statistics of Earth's temporarily-captured natural satellites. The steady-state population in both cases (constant and quadratic number distributions inside the e and i bins) is predicted to contain a slightly reduced number of meter-sized asteroids compared to the values of the previous paper. For the combined TCO/TCF population, we find the largest body constantly present on a geocentric orbit to be on the order of 80 cm in diameter. In the phase space, where the capture is possible, the capture efficiency of TCOs and TCFs is O(10-6 -10-4) . We also find that kilometer-scale asteroids are captured once every 10 Myr.

  11. Prediction of maximum casting defect size in MAR-M-247 alloy processed by hot isostatic pressing

    Directory of Open Access Journals (Sweden)

    Miroslav Šmíd

    2015-02-01

    Full Text Available Nickel based MAR-M-247 superalloy treated by hot isostatic pressing was investigated with the aim to identify the influence of casting defect size on fatigue life. Two testing temperatures of 650 and 800°C and one stress amplitude were chosen for fatigue tests. The Murakami approach and the largest extreme value distribution theory were applied. It has been found that the maximum size of casting defects in a specimen can be satisfactorily predicted. Fatigue life of specimens was in the good agreement with assumptions based on the evaluation and prediction of the casting defect size.

  12. Size Dependence of First-order Hyperpolarizability of CdS Nanoparticles Studied by Hyper-Rayleigh Scattering

    Institute of Scientific and Technical Information of China (English)

    Yu ZHANG; Kun Ji CHEN; Xin WANG; Ming MA; De Gang FU; Ning GU; Ju Zheng LIU; Zu Hong LU; Ling XU; Jun XU

    2003-01-01

    The second-order optical nonlinearity of CdS nanoparticles with different diameters of28.0, 30.0, 31.5, 50.0, and 91.0 3 was studied by hyper-Rayleigh scattering technique. Resultsshow that the first-order hyperpolarizability β value per CdS particle decreases as size is reduced todiameter of 31.5 A; however, as CdS size further decreases, this trend is reversed and β valueincreases. Substantially, the normalized β value per CdS formula unit, β0, exhibits systematicenhancement with decreasing size. This phenomenon is interpreted in terms of a so-calledsurface contribution mechanism.

  13. Enhanced Immunostimulating Activity of Lactobacilli-Mimicking Materials by Controlling Size.

    Science.gov (United States)

    Nagahama, Koji; Kumano, Takayuki; Nakagawa, Yuichi; Oyama, Naho; Tsuji, Hirokazu; Moriyama, Kaoru; Shida, Kan; Nomoto, Koji; Chiba, Katsuyoshi; Koumoto, Kazuya; Matsui, Jun

    2015-08-19

    The design and synthesis of materials capable of activating the immune system in a safe manner is of great interest in immunology and related fields. Lactobacilli activate the innate immune system of a host when acting as probiotics. Here, we constructed lactobacilli-mimicking materials in which polysaccharide-peptidoglycan complexes (PS-PGs) derived from lactobacilli were covalently conjugated to the surfaces of polymeric microparticles with a wide variety of sizes, ranging from 200 nm to 3 μm. The artificial lactobacilli successfully stimulated macrophages without cytotoxicity. Importantly, we found that the size of artificial lactobacilli strongly influenced their immunostimulating activities, and that artificial lactobacilli of 1 μm exhibited 10-fold higher activity than natural lactobacilli. One major advantage of the artificial lactobacilli is facile control of size, which cannot be changed in natural lactobacilli. These findings provide new insights into the design of materials for immunology as well as the molecular biology of lactobacillus.

  14. Core size determination and structural characterization of intravenous iron complexes by cryogenic transmission electron microscopy.

    Science.gov (United States)

    Wu, Yong; Petrochenko, Peter; Chen, Lynn; Wong, Sook Yee; Absar, Mohammad; Choi, Stephanie; Zheng, Jiwen

    2016-05-30

    Understanding physicochemical properties of intravenous (IV) iron drug products is essential to ensure the manufacturing process is consistent and streamlined. The history of physicochemical characterization of IV iron complex formulations stretches over several decades, with disparities in iron core size and particle morphology as the major source of debate. One of the main reasons for this controversy is room temperature sample preparation artifacts, which affect accurate determination of size, shape and agglomeration/aggregation of nanoscale iron particles. The present study is first to report the ultra-fine iron core structures of four IV iron complex formulations, sodium ferric gluconate, iron sucrose, low molecular weight iron dextran and ferumoxytol, using a cryogenic transmission electron microscopy (cryo-TEM) preservation technique, as opposed to the conventional room temperature (RT-TEM) technique. Our results show that room temperature preparation causes nanoparticle aggregation and deformation, while cryo-TEM preserves IV iron colloidal suspension in their native frozen-hydrated and undiluted state. In contrast to the current consensus in literature, all four IV iron colloids exhibit a similar morphology of their iron oxide cores with a spherical shape, narrow size distribution and an average size of 2nm. Moreover, out of the four tested formulations, ferumoxytol exhibits a cluster-like community of several iron carbohydrate particles which likely accounts for its large hydrodynamic size of 25nm, measured with dynamic light scattering. Our findings outline a suitable method for identifying colloidal nanoparticle core size in the native state, which is increasingly important for manufacturing and design control of complex drug formulations, such as IV iron drug products.

  15. Interspecies avian brain chimeras reveal that large brain size differences are influenced by cell-interdependent processes.

    Science.gov (United States)

    Chen, Chun-Chun; Balaban, Evan; Jarvis, Erich D

    2012-01-01

    Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged telencephalon in adulthood relative to vocal non-learning birds. To determine if this size difference results from evolutionary changes in cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala from zebra finch donors (a vocal-learning species) into Japanese quail hosts (a vocal non-learning species) during the early neural tube stage (day 2 of incubation), and harvested the chimeras at later embryonic stages (between 9-12 days of incubation). The donor and host tissues fused well with each other, with known major fiber pathways connecting the zebra finch and quail parts of the brain. However, the overall sizes of chimeric finch telencephala were larger than non-transplanted finch telencephala at the same developmental stages, even though the proportional sizes of telencephalic subregions and fiber tracts were similar to normal finches. There were no significant changes in the size of chimeric quail host midbrains, even though they were innervated by the physically smaller zebra finch brain, including the smaller retinae of the finch eyes. Chimeric zebra finch telencephala had a decreased cell density relative to normal finches. However, cell nucleus size differences between each species were maintained as in normal birds. These results suggest that telencephalic size development is partially cell-interdependent, and that the mechanisms controlling the size of different brain regions may be functionally independent.

  16. Interspecies avian brain chimeras reveal that large brain size differences are influenced by cell-interdependent processes.

    Directory of Open Access Journals (Sweden)

    Chun-Chun Chen

    Full Text Available Like humans, birds that exhibit vocal learning have relatively delayed telencephalon maturation, resulting in a disproportionately smaller brain prenatally but enlarged telencephalon in adulthood relative to vocal non-learning birds. To determine if this size difference results from evolutionary changes in cell-autonomous or cell-interdependent developmental processes, we transplanted telencephala from zebra finch donors (a vocal-learning species into Japanese quail hosts (a vocal non-learning species during the early neural tube stage (day 2 of incubation, and harvested the chimeras at later embryonic stages (between 9-12 days of incubation. The donor and host tissues fused well with each other, with known major fiber pathways connecting the zebra finch and quail parts of the brain. However, the overall sizes of chimeric finch telencephala were larger than non-transplanted finch telencephala at the same developmental stages, even though the proportional sizes of telencephalic subregions and fiber tracts were similar to normal finches. There were no significant changes in the size of chimeric quail host midbrains, even though they were innervated by the physically smaller zebra finch brain, including the smaller retinae of the finch eyes. Chimeric zebra finch telencephala had a decreased cell density relative to normal finches. However, cell nucleus size differences between each species were maintained as in normal birds. These results suggest that telencephalic size development is partially cell-interdependent, and that the mechanisms controlling the size of different brain regions may be functionally independent.

  17. The regulation of lipid droplet size and phospholipid composition by stearoyl-CoA desaturase

    DEFF Research Database (Denmark)

    Shi, Xun; Li, Juan; Zou, Xiaoju;

    2013-01-01

    desaturase mutants, independently, and in combination with mutants disrupted in conserved lipid metabolic pathways. C. elegans with impaired SCD activity displayed both reduced fat stores and decreased lipid droplet size. Mutants in the daf-2 (insulin-like growth factor receptor), rsks-1 (homolog of p70S6......Fatty acid desaturation regulates membrane function and fat storage in animals. To determine the contribution of stearoyl-CoA desaturase (SCD) activity on fat storage and development in the nematode Caenorhabditis elegans, we analyzed the lipid composition and lipid droplet size in the fat-6;fat-7...

  18. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chaopeng; Gao, Yimin; Zhou, Yucheng [Xi' an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi' an, Shaanxi Province (China); Wei, Shizhong [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China); Henan University of Science and Technology, Engineering Research Center of Tribology and Materials Protection, Ministry of Education, Luoyang (China); Zhang, Guoshang; Zhu, Xiangwei; Guo, Songliang [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China)

    2016-03-15

    The nano-sized ZrO{sub 2}-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO{sub 2} particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO{sub 2} particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO{sub 2} particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  19. Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

  20. Enhancing sampling design in mist-net bat surveys by accounting for sample size optimization.

    Science.gov (United States)

    Trevelin, Leonardo Carreira; Novaes, Roberto Leonan Morim; Colas-Rosas, Paul François; Benathar, Thayse Cristhina Melo; Peres, Carlos A

    2017-01-01

    The advantages of mist-netting, the main technique used in Neotropical bat community studies to date, include logistical implementation, standardization and sampling representativeness. Nonetheless, study designs still have to deal with issues of detectability related to how different species behave and use the environment. Yet there is considerable sampling heterogeneity across available studies in the literature. Here, we approach the problem of sample size optimization. We evaluated the common sense hypothesis that the first six hours comprise the period of peak night activity for several species, thereby resulting in a representative sample for the whole night. To this end, we combined re-sampling techniques, species accumulation curves, threshold analysis, and community concordance of species compositional data, and applied them to datasets of three different Neotropical biomes (Amazonia, Atlantic Forest and Cerrado). We show that the strategy of restricting sampling to only six hours of the night frequently results in incomplete sampling representation of the entire bat community investigated. From a quantitative standpoint, results corroborated the existence of a major Sample Area effect in all datasets, although for the Amazonia dataset the six-hour strategy was significantly less species-rich after extrapolation, and for the Cerrado dataset it was more efficient. From the qualitative standpoint, however, results demonstrated that, for all three datasets, the identity of species that are effectively sampled will be inherently impacted by choices of sub-sampling schedule. We also propose an alternative six-hour sampling strategy (at the beginning and the end of a sample night) which performed better when resampling Amazonian and Atlantic Forest datasets on bat assemblages. Given the observed magnitude of our results, we propose that sample representativeness has to be carefully weighed against study objectives, and recommend that the trade-off between