Streamflow and nutrient dependence of temperature effects on dissolved oxygen in low-order forest streams

Treesearch

April Mason; Y. Jun Xu; Philip Saksa; Adrienne Viosca; Johnny M. Grace; John Beebe; Richard Stich

2007-01-01

Low dissolved oxygen (DO) concentrations in streams can be linked to both natural conditions and human activities. In Louisiana, natural stream conditions such as low flow, high temperature and high organic content, often result in DO levels already below current water quality criteria, making it difficult to develop standards for Best Management Practices (BMPs)....

Boundaries for biofilm formation: humidity and temperature.

PubMed

Else, Terry Ann; Pantle, Curtis R; Amy, Penny S

2003-08-01

Environmental conditions which define boundaries for biofilm production could provide useful ecological information for biofilm models. A practical use of defined conditions could be applied to the high-level nuclear waste repository at Yucca Mountain. Data for temperature and humidity conditions indicate that decreases in relative humidity or increased temperature severely affect biofilm formation on three candidate canister metals.

Routes to High-Temperature Superconductivity: A Lesson from FeSe/SrTiO3

NASA Astrophysics Data System (ADS)

Lee, Dung-Hai

2018-03-01

Raising the superconducting transition temperature to a point where applications are practical is one of the most important challenges in science. In this review, we aim at gaining insights on the Tc controlling factors for a particular high-temperature superconductor family - the FeSe-based superconductors. In particular, we discuss the mechanisms by which the Cooper pairing temperature is enhanced from ˜8 K in bulk FeSe to ˜80 K in the interface between an atomic layer of FeSe and SrTiO3. This includes the experimental hints and the theoretical simulation of the involved mechanisms. We end by applying these insights to suggest some possible high-temperature superconducting systems.

Ultrahigh-sensitive sensing platform based on p-type dumbbell-like Co3O4 network

NASA Astrophysics Data System (ADS)

Zhou, Tingting; Zhang, Tong; Zhang, Rui; Lou, Zheng; Deng, Jianan; Wang, Lili

2017-12-01

Development of high performance room temperature sensors remains a grand challenge for high demand of practical application. Metal oxide semiconductors (MOSs) have many advantages over others due to their easy functionalization, high surface area, and low cost. However, they typically need a high work temperature during sensing process. Here, p-type sensing layer is reported, consisting of pore-rich dumbbell-like Co3O4 particles (DP-Co3O4) with intrinsic high catalytic activity. The gas sensor (GS) based DP-Co3O4 catalyst exhibits ultrahigh NH3 sensing activity along with excellent stability over other structure based NH3 GSs in room temperature work environment. In addition, the unique structure of DP-Co3O4 with pore-rich and high catalytic activity endows fast gas diffusion rate and high sensitivity at room temperature. Taken together, the findings in this work highlight the merit of integrating highly active materials in p-type materials, offering a framework to develop high-sensitivity room temperature sensing platforms.

A practical cooling strategy for reducing the physiological strain associated with firefighting activity in the heat.

PubMed

Barr, D; Gregson, W; Sutton, L; Reilly, T

2009-04-01

The aim of this study was to establish whether a practical cooling strategy reduces the physiological strain during simulated firefighting activity in the heat. On two separate occasions under high ambient temperatures (49.6 +/- 1.8 degrees C, relative humidity (RH) 13 +/- 2%), nine male firefighters wearing protective clothing completed two 20-min bouts of treadmill walking (5 km/h, 7.5% gradient) separated by a 15-min recovery period, during which firefighters were either cooled (cool) via application of an ice vest and hand and forearm water immersion ( approximately 19 degrees C) or remained seated without cooling (control). There was no significant difference between trials in any of the dependent variables during the first bout of exercise. Core body temperature (37.72 +/- 0.34 vs. 38.21 +/- 0.17 degrees C), heart rate (HR) (81 +/- 9 vs. 96 +/- 17 beats/min) and mean skin temperature (31.22 +/- 1.04 degrees C vs. 33.31 +/- 1 degrees C) were significantly lower following the recovery period in cool compared with control (p < 0.05). Core body temperature remained consistently lower (0.49 +/- 0.02 degrees C; p < 0.01) throughout the second bout of activity in cool compared to control. Mean skin temperature, HR and thermal sensation were significantly lower during bout 2 in cool compared with control (p < 0.05). It is concluded that this practical cooling strategy is effective at reducing the physiological strain associated with demanding firefighting activity under high ambient temperatures.

Design of shared instruments to utilize simulated gravities generated by a large-gradient, high-field superconducting magnet.

PubMed

Wang, Y; Yin, D C; Liu, Y M; Shi, J Z; Lu, H M; Shi, Z H; Qian, A R; Shang, P

2011-03-01

A high-field superconducting magnet can provide both high-magnetic fields and large-field gradients, which can be used as a special environment for research or practical applications in materials processing, life science studies, physical and chemical reactions, etc. To make full use of a superconducting magnet, shared instruments (the operating platform, sample holders, temperature controller, and observation system) must be prepared as prerequisites. This paper introduces the design of a set of sample holders and a temperature controller in detail with an emphasis on validating the performance of the force and temperature sensors in the high-magnetic field.

Design of shared instruments to utilize simulated gravities generated by a large-gradient, high-field superconducting magnet

NASA Astrophysics Data System (ADS)

Wang, Y.; Yin, D. C.; Liu, Y. M.; Shi, J. Z.; Lu, H. M.; Shi, Z. H.; Qian, A. R.; Shang, P.

2011-03-01

A high-field superconducting magnet can provide both high-magnetic fields and large-field gradients, which can be used as a special environment for research or practical applications in materials processing, life science studies, physical and chemical reactions, etc. To make full use of a superconducting magnet, shared instruments (the operating platform, sample holders, temperature controller, and observation system) must be prepared as prerequisites. This paper introduces the design of a set of sample holders and a temperature controller in detail with an emphasis on validating the performance of the force and temperature sensors in the high-magnetic field.

The Effects of Commercial Cool Water Washing of Shell Eggs on Haugh Unit, Vitelline Membrane Strength, Aerobic Microorganisms and Fungi

USDA-ARS?s Scientific Manuscript database

Current egg washing practices utilize wash water temperatures averaging 49°C, and have been found to increase internal egg temperature by 6.7 to 7.8°C. These high temperatures create a more optimal environment for bacterial growth, including Salmonella Enteritidis (SE), if it is present. SE is the...

Boundaries for Biofilm Formation: Humidity and Temperature

PubMed Central

Else, Terry Ann; Pantle, Curtis R.; Amy, Penny S.

2003-01-01

Environmental conditions which define boundaries for biofilm production could provide useful ecological information for biofilm models. A practical use of defined conditions could be applied to the high-level nuclear waste repository at Yucca Mountain. Data for temperature and humidity conditions indicate that decreases in relative humidity or increased temperature severely affect biofilm formation on three candidate canister metals. PMID:12902302

Effects of stress ratio on the temperature-dependent high-cycle fatigue properties of alloy steels

NASA Astrophysics Data System (ADS)

Lü, Zhi-yang; Wan, Ao-shuang; Xiong, Jun-jiang; Li, Kuang; Liu, Jian-zhong

2016-12-01

This paper addresses the effects of stress ratio on the temperature-dependent high-cycle fatigue (HCF) properties of alloy steels 2CrMo and 9CrCo, which suffer from substantial vibrational loading at small stress amplitude, high stress ratio, and high frequency in the high-temperature environments in which they function as blade and rotor spindle materials in advanced gas or steam turbine engines. Fatigue tests were performed on alloy steels 2CrMo and 9CrCo subjected to constant-amplitude loading at four stress ratios and at four and three temperatures, respectively, to determine their temperature-dependent HCF properties. The interaction mechanisms between high temperature and stress ratio were deduced and compared with each other on the basis of the results of fractographic analysis. A phenomenological model was developed to evaluate the effects of stress ratio on the temperature-dependent HCF properties of alloy steels 2CrMo and 9CrCo. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.

A multi-core fiber based interferometer for high temperature sensing

NASA Astrophysics Data System (ADS)

Zhou, Song; Huang, Bo; Shu, Xuewen

2017-04-01

In this paper, we have verified and implemented a Mach-Zehnder interferometer based on seven-core fiber for high temperature sensing application. This proposed structure is based on a multi-mode-multi-core-multi-mode fiber structure sandwiched by a single mode fiber. Between the single-mode and multi-core fiber, a 3 mm long multi-mode fiber is formed for lead-in and lead-out light. The basic operation principle of this device is the use of multi-core modes, single-mode and multi-mode interference coupling is also utilized. Experimental results indicate that this interferometer sensor is capable of accurate measurements of temperatures up to 800 °C, and the temperature sensitivity of the proposed sensor is as high as 170.2 pm/°C, which is much higher than the current existing MZI based temperature sensors (109 pm/°C). This type of sensor is promising for practical high temperature applications due to its advantages including high sensitivity, simple fabrication process, low cost and compactness.

Vortex pinning properties in Fe-chalcogenides

NASA Astrophysics Data System (ADS)

Leo, A.; Grimaldi, G.; Guarino, A.; Avitabile, F.; Nigro, A.; Galluzzi, A.; Mancusi, D.; Polichetti, M.; Pace, S.; Buchkov, K.; Nazarova, E.; Kawale, S.; Bellingeri, E.; Ferdeghini, C.

2015-12-01

Among the families of iron-based superconductors, the 11-family is one of the most attractive for high field applications at low temperatures. Optimization of the fabrication processes for bulk, crystalline and/or thin film samples is the first step in producing wires and/or tapes for practical high power conductors. Here we present the results of a comparative study of pinning properties in iron-chalcogenides, investigating the flux pinning mechanisms in optimized Fe(Se{}1-xTe x ) and FeSe samples by current-voltage characterization, magneto-resistance and magnetization measurements. In particular, from Arrhenius plots in magnetic fields up to 9 T, the activation energy is derived as a function of the magnetic field, {U}0(H), whereas the activation energy as a function of temperature, U(T), is derived from relaxation magnetization curves. The high pinning energies, high upper critical field versus temperature slopes near critical temperatures, and highly isotropic pinning properties make iron-chalcogenide superconductors a technological material which could be a real competitor to cuprate high temperature superconductors for high field applications.

Practical polarization maintaining optical fibre temperature sensor for harsh environment application

NASA Astrophysics Data System (ADS)

Yang, Yuanhong; Xia, Haiyun; Jin, Wei

2007-10-01

A reflection spot temperature sensor was proposed based on the polarization mode interference in polarization maintaining optical fibre (PMF) and the phenomenon that the propagation constant difference of the two orthogonal polarization modes in stressing structures PMF is sensitive to temperature and the sensing equation was obtained. In this temperature sensor, a broadband source was used to suppress the drift due to polarization coupling in lead-in/lead-out PMF. A characteristic and performance investigation proved this sensor to be practical, flexible and precise. Experimental results fitted the theory model very well and the noise-limited minimum detectable temperature variation is less than 0.01 °C. The electric arc processing was investigated and the differential propagation constant modifying the PMF probe is performed. For the demand of field hot-spot monitoring of huge power transformers, a remote multi-channel temperature sensor prototype has been made and tested. Specially coated Panda PMF that can stand high temperatures up to 250 °C was fabricated and used as probe fibres. The sensor probes were sealed within thin quartz tubes that have high voltage insulation and can work in a hot oil and vapour environment. Test results show that the accuracy of the system is better than ±0.5 °C within 0 °C to 200 °C.

Planar temperature measurement in compressible flows using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1991-01-01

A laser-induced iodine fluorescence technique that is suitable for the planar measurement of temperature in cold nonreacting compressible air flows is investigated analytically and demonstrated in a known flow field. The technique is based on the temperature dependence of the broadband fluorescence from iodine excited by the 514-nm line of an argon-ion laser. Temperatures ranging from 165 to 245 K were measured in the calibration flow field. This technique makes complete, spatially resolved surveys of temperature practical in highly three-dimensional, low-temperature compressible flows.

Astigmatic Herriott cell for optical refrigeration

NASA Astrophysics Data System (ADS)

Gragossian, Aram; Meng, Junwei; Ghasemkhani, Mohammadreza; Albrecht, Alexander R.; Sheik-Bahae, Mansoor

2017-01-01

Cooling rare-earth-doped crystals to the lowest temperature possible requires enhanced resonant absorption and high-purity crystals. Since resonant absorption decreases as the crystal is cooled, the only path forward is to increase the number of roundtrips that the laser makes inside the crystal. To achieve even lower temperatures than previously reported, we have employed an astigmatic Herriott cell to improve laser absorption at low temperatures. Preliminary results indicate improvement over previous designs. This cavity potentially enables us to use unpolarized high-power fiber lasers, and to achieve much higher cooling power for practical applications.

LDA-Mediated Synthesis of Triarylmethanes by Arylation of Diarylmethanes with Fluoroarenes at Room Temperature.

PubMed

Ji, Xinfei; Huang, Tao; Wu, Wei; Liang, Fang; Cao, Song

2015-10-16

A practical and convenient approach for the secondary C(sp(3))-H arylation of diarylmethanes with various fluoroarenes is described. The reaction proceeds smoothly in the presence of LDA (lithium diisopropylamide) at room temperature and affords triarylmethanes in moderate to high yields.

Controlled destruction and temperature distributions in biological tissues subjected to monoactive electrocoagulation.

PubMed

Erez, A; Shitzer, A

1980-02-01

An analysis of the temperature fields developed in a biological tissue undergoing a monoactive electrical coagulating process is presented, including thermal recovery following prolonged heating. The analysis is performed for the passage of alternating current and assumes a homogeneous and isotropic tissue model which is uniformly perfused by blood at arterial temperature. Solution for the one-dimensional spherical geometry is obtained by a Laplace transform and numerical integrations. Results obtained indicate the major role which blood perfusion plays in determining the effects of the coagulating process; tissue temperatures and depth of destruction are drastically reduced as blood perfusion increases. Metabolic heat generation rate is found to have negligible effects on tissue temperatures whereas electrode thermal inertia affects temperature levels appreciably. However, electrodes employed in practice would have a low thermal inertia which might be regarded as zero for all practical purposes. It is also found that the depth of tissue destruction is almost directly proportional to the electrical power and duration of application. To avoid excessively high temperatures and charring, it would be advantageous to reduce power and increase the time of application. Results of this study should be regarded as a first approximation to the rather complex phenomena associated with electrocoagulation. They may, nevertheless, serve as preliminary guidelines to practicing surgeons applying this technique.

High-Temperature Electronics: A Role for Wide Bandgap Semiconductors?

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.; Okojie, Robert S.; Chen, Liang-Yu

2002-01-01

It is increasingly recognized that semiconductor based electronics that can function at ambient temperatures higher than 150 C without external cooling could greatly benefit a variety of important applications, especially-in the automotive, aerospace, and energy production industries. The fact that wide bandgap semiconductors are capable of electronic functionality at much higher temperatures than silicon has partially fueled their development, particularly in the case of SiC. It appears unlikely that wide bandgap semiconductor devices will find much use in low-power transistor applications until the ambient temperature exceeds approximately 300 C, as commercially available silicon and silicon-on-insulator technologies are already satisfying requirements for digital and analog very large scale integrated circuits in this temperature range. However, practical operation of silicon power devices at ambient temperatures above 200 C appears problematic, as self-heating at higher power levels results in high internal junction temperatures and leakages. Thus, most electronic subsystems that simultaneously require high-temperature and high-power operation will necessarily be realized using wide bandgap devices, once the technology for realizing these devices become sufficiently developed that they become widely available. Technological challenges impeding the realization of beneficial wide bandgap high ambient temperature electronics, including material growth, contacts, and packaging, are briefly discussed.

New iodide-based molten salt systems for high temperature molten salt batteries

NASA Astrophysics Data System (ADS)

Fujiwara, Syozo; Kato, Fumio; Watanabe, Syouichiro; Inaba, Minoru; Tasaka, Akimasa

Novel multi-component molten salt systems containing iodides, LiF-LiBr-LiI, LiF-NaBr-LiI, and LiF-LiCl-LiBr-LiI, were investigated for use as electrolytes in high temperature molten salt batteries to improve the discharge rate-capability. The iodide-based molten salts showed higher ionic conductivity (∼3 S cm -1 at 500 °C) than conventional LiCl-KCl, and had low enough melting points (below 400 °C) that can be used in practical high temperature molten salt batteries. The iodide-based salts showed instability at temperatures higher than 280 °C in dried air. The decomposition mechanism of iodide-based molten salts was discussed, and it was found that elimination of oxygen from the environment is effective to stabilize the iodide-based molten salts at high temperatures.

A simple mathematical method to estimate ammonia emission from in-house windrowing of poultry litter

USDA-ARS?s Scientific Manuscript database

In house windrowing between flocks is an emerging sanitary management practice to partially disinfect the built-up litter in broiler houses. Windrowing litter results in high litter temperatures that can reduce the risk of transmitting pathogens to next flock. Simultaneously, this practice may also ...

Greenhouse gas and ammonia emission from a litter-windrowing in bird houses

USDA-ARS?s Scientific Manuscript database

One of emerging poultry manure management practices is in house windrowing to disinfect the litter. With this practice, growers windrow the litter in broiler houses between flocks, usually for 2 weeks. This results in high litter temperatures that can reduce pathogens in the litter. However, this p...

Ammonia and nitrous oxide emissions from broiler houses with downtime windrowed litter

USDA-ARS?s Scientific Manuscript database

An emerging poultry manure management practice is in house windrowing to disinfect the litter. With this practice, growers windrow the litter in broiler houses between flocks, usually for 2 weeks. This results in high litter temperatures that can reduce pathogens in the litter. However, this practi...

Very high temperature fiber processing and testing through the use of ultrahigh solar energy concentration

NASA Astrophysics Data System (ADS)

Jacobson, Benjamin A.; Gleckman, Philip L.; Holman, Robert L.; Sagie, Daniel; Winston, Roland

1991-10-01

We have demonstrated the feasibility of a high temperature cool-wall optical furnace that harnesses the unique power of concentrated solar heating for advanced materials processing and testing. Out small-scale test furnace achieved temperatures as high as 2400 C within a 10 mm X 0.44 mm cylindrical hot-zone. Optimum performance and efficiency resulted from an innovative two-stage optical design using a long-focal length, point-focus, conventional primary concentrator and a non-imaging secondary concentrator specifically designed for the cylindrical geometry of the target fiber. A scale-up analysis suggests that even higher temperatures can be achieved over hot zones large enough for practical commercial fiber post- processing and testing.

A polytetrafluorethylene insulated cable for high temperature oxygen aerospace applications

NASA Technical Reports Server (NTRS)

Sheppard, A. T.; Webber, R. G.

1983-01-01

For electrical cables to function and survive in the severe high temperature oxygen environment that will be experienced in the external tanks of the space shuttle, extreme cleanliness and material purity is required. A flexible light weight cable has been developed for use in pure oxygen at worst case temperatures of -190 to +260 degrees Centigrade and pressures as high as 44 pounds per square inch absolute. A comprehensive series of tests were performed on cables manufactured to the best commercial practices in order to establish the basic guidelines for control of build configuration as well as each material used in construction of the cable.

Structure of deformed silicon and implications for low cost solar cells

NASA Technical Reports Server (NTRS)

Mardesich, N.; Leipold, M. H.; Turner, G. B.; Digges, T. G., Jr.

1978-01-01

The microstructure and minority carrier lifetime of silicon were investigated in uniaxially compressed silicon samples. The objective of the investigation was to determine if it is feasible to produce silicon solar cells from sheet formed by high temperature rolling. The initial structure of the silicon samples ranged from single crystal to fine-grained polycrystals. The samples had been deformed at strain rates of 0.1 to 8.5/sec and temperatures of 1270-1380 C with subsequent annealing at 1270-1380 C. The results suggest that high temperature rolling of silicon to produce sheet for cells of high efficiency is not practical.

A polytetrafluorethylene insulated cable for high temperature oxygen aerospace applications

NASA Astrophysics Data System (ADS)

Sheppard, A. T.; Webber, R. G.

For electrical cables to function and survive in the severe high temperature oxygen environment that will be experienced in the external tanks of the space shuttle, extreme cleanliness and material purity is required. A flexible light weight cable has been developed for use in pure oxygen at worst case temperatures of -190 to +260 degrees Centigrade and pressures as high as 44 pounds per square inch absolute. A comprehensive series of tests were performed on cables manufactured to the best commercial practices in order to establish the basic guidelines for control of build configuration as well as each material used in construction of the cable.

High-irradiance reactor design with practical unfolded optics

NASA Astrophysics Data System (ADS)

Feuermann, Daniel; Gordon, Jeffrey M.

2008-08-01

In the design of high-temperature chemical reactors and furnaces, as well as high-radiance light projection applications, reconstituting the ultra-high radiance of short-arc discharge lamps at maximum radiative efficiency constitutes a significant challenge. The difficulty is exacerbated by the high numerical aperture necessary at both the source and the target. Separating the optic from both the light source and the target allows practical operation, control, monitoring, diagnostics and maintenance. We present near-field unfolded aplanatic optics as a feasible solution. The concept is illustrated with a design customized to a high-temperature chemical reactor for nano-material synthesis, driven by an ultra-bright xenon short-arc discharge lamp, with near-unity numerical aperture for both light input and light output. We report preliminary optical measurements for the first prototype, which constitutes a double-ellipsoid solution. We also propose compound unfolded aplanats that collect the full angular extent of lamp emission (in lieu of light recycling optics) and additionally permit nearly full-circumference irradiation of the reactor.

Temperature metrology

NASA Astrophysics Data System (ADS)

Fischer, J.; Fellmuth, B.

2005-05-01

The majority of the processes used by the manufacturing industry depend upon the accurate measurement and control of temperature. Thermal metrology is also a key factor affecting the efficiency and environmental impact of many high-energy industrial processes, the development of innovative products and the health and safety of the general population. Applications range from the processing, storage and shipment of perishable foodstuffs and biological materials to the development of more efficient and less environmentally polluting combustion processes for steel-making. Accurate measurement and control of temperature is, for instance, also important in areas such as the characterization of new materials used in the automotive, aerospace and semiconductor industries. This paper reviews the current status of temperature metrology. It starts with the determination of thermodynamic temperatures required on principle because temperature is an intensive quantity. Methods to determine thermodynamic temperatures are reviewed in detail to introduce the underlying physical basis. As these methods cannot usually be applied for practical measurements the need for a practical temperature scale for day-to-day work is motivated. The International Temperature Scale of 1990 and the Provisional Low Temperature Scale PLTS-2000 are described as important parts of the International System of Units to support science and technology. Its main importance becomes obvious in connection with industrial development and international markets. Every country is strongly interested in unique measures, in order to guarantee quality, reproducibility and functionability of products. The eventual realization of an international system, however, is only possible within the well-functioning organization of metrological laboratories. In developed countries the government established scientific institutes have certain metrological duties, as, for instance, the maintenance and dissemination of national units. For the base unit kelvin, this procedure is described in the sections on practical temperature scales, practical thermometry and reference standards. Testing experimentally the fundamental laws of physics means in practice the precise determination of the fundamental constants appearing in the laws. The essence of current activities is that prototypes, which may vary uncontrollably with time and location, are replaced by abstract experimental prescriptions that relate the units to the constants. This approach is shown for the definition of the kelvin and the Boltzmann constant. Dedicated to the occasion of the 60th birthday of Wolfgang Buck.

Method of Analysis by the U.S. Geological Survey California District Sacramento Laboratory-- Determination of Dissolved Organic Carbon in Water by High Temperature Catalytic Oxidation, Method Validation, and Quality-Control Practices

USGS Publications Warehouse

Bird, Susan M.; Fram, Miranda S.; Crepeau, Kathryn L.

2003-01-01

An analytical method has been developed for the determination of dissolved organic carbon concentration in water samples. This method includes the results of the tests used to validate the method and the quality-control practices used for dissolved organic carbon analysis. Prior to analysis, water samples are filtered to remove suspended particulate matter. A Shimadzu TOC-5000A Total Organic Carbon Analyzer in the nonpurgeable organic carbon mode is used to analyze the samples by high temperature catalytic oxidation. The analysis usually is completed within 48 hours of sample collection. The laboratory reporting level is 0.22 milligrams per liter.

The temperature of unheated bodies in a high-speed gas stream

NASA Technical Reports Server (NTRS)

Eckert, E; Weise, W

1941-01-01

The present report deals with temperature measurements on cylinders of 0.2 to 3 millimeters diameter in longitudinal and transverse air flow at speeds of 100 to 300 meters per second. Within the explored test range, that is, the probable laminar boundary layer region, the temperature of the cylinders in axial flow is practically independent of the speed and in good agreement with Pohlhausen's theoretical values; Whereas, in transverse flow, cylinders of certain diameter manifest a close relationship with speed, the ratio of the temperature above the air of the body to the adiabatic stagnation temperature decreases with rising speed and then rises again from a Mach number of 0.6. The importance of this "specific temperature" of the body for heat-transfer studies at high speed is discussed.

High-Temperature Ceramic Matrix Composite with High Corrosion Resistance

DTIC Science & Technology

2010-06-02

ceramics with silicide additives may be explained in the following ways: 1) metal oxide, for example Ta2O5, formed at oxidation of TaSi2, in the...practically monophase ones, possibly, the additives of corresponding metals in silicide powders were present in insignificant amounts. For...boride with zirconium silicide we prepared the mixtures with 20 vol. % of silicide , the latter being hot pressed in the temperature range of 1600

Separating heat stress from moisture stress: analyzing yield response to high temperature in irrigated maize

NASA Astrophysics Data System (ADS)

Carter, Elizabeth K.; Melkonian, Jeff; Riha, Susan J.; Shaw, Stephen B.

2016-09-01

Several recent studies have indicated that high air temperatures are limiting maize (Zea mays L.) yields in the US Corn Belt and project significant yield losses with expected increases in growing season temperatures. Further work has suggested that high air temperatures are indicative of high evaporative demand, and that decreases in maize yields which correlate to high temperatures and vapor pressure deficits (VPD) likely reflect underlying soil moisture limitations. It remains unclear whether direct high temperature impacts on yields, independent of moisture stress, can be observed under current temperature regimes. Given that projected high temperature and moisture may not co-vary the same way as they have historically, quantitative analyzes of direct temperature impacts are critical for accurate yield projections and targeted mitigation strategies under shifting temperature regimes. To evaluate yield response to above optimum temperatures independent of soil moisture stress, we analyzed climate impacts on irrigated maize yields obtained from the National Corn Growers Association (NCGA) corn yield contests for Nebraska, Kansas and Missouri. In irrigated maize, we found no evidence of a direct negative impact on yield by daytime air temperature, calculated canopy temperature, or VPD when analyzed seasonally. Solar radiation was the primary yield-limiting climate variable. Our analyses suggested that elevated night temperature impacted yield by increasing rates of phenological development. High temperatures during grain-fill significantly interacted with yields, but this effect was often beneficial and included evidence of acquired thermo-tolerance. Furthermore, genetics and management—information uniquely available in the NCGA contest data—explained more yield variability than climate, and significantly modified crop response to climate. Thermo-acclimation, improved genetics and changes to management practices have the potential to partially or completely offset temperature-related yield losses in irrigated maize.

A new practical approach towards the synthesis of unsymmetric and symmetric 1,10-phenanthroline derivatives at room temperature.

PubMed

Cheng, Yongfeng; Han, Xuesong; Ouyang, Huangche; Rao, Yu

2012-03-18

An efficient method towards synthesis of 1,10-phenanthrolines is described. Through Lewis acid-catalyzed annulation reaction between 3-ethoxycyclobutanones and 8-aminoquinolines, a variety of unsymmetric and symmetric 1,10-phenanthroline derivatives were readily prepared with high regioselectivity at room temperature.

16 CFR § 1633.7 - Mattress test procedure.

Code of Federal Regulations, 2013 CFR

2013-01-01

... of oxygen consumption calorimetry. The calibration should follow generally accepted practices for... conditions shall be maintained at a temperature greater than 15 °C (59 °F) and less than 27 °C (80.6 °F) and... it with a suitable layer of high temperature insulation to protect the equipment. Both copper tubes...

High-density magnetoresistive random access memory operating at ultralow voltage at room temperature.

PubMed

Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

2011-11-22

The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch(-2), ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

High-density magnetoresistive random access memory operating at ultralow voltage at room temperature

PubMed Central

Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

2011-01-01

The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch−2, ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns. PMID:22109527

An overview of rotating machine systems with high-temperature bulk superconductors

NASA Astrophysics Data System (ADS)

Zhou, Difan; Izumi, Mitsuru; Miki, Motohiro; Felder, Brice; Ida, Tetsuya; Kitano, Masahiro

2012-10-01

The paper contains a review of recent advancements in rotating machines with bulk high-temperature superconductors (HTS). The high critical current density of bulk HTS enables us to design rotating machines with a compact configuration in a practical scheme. The development of an axial-gap-type trapped flux synchronous rotating machine together with the systematic research works at the Tokyo University of Marine Science and Technology since 2001 are briefly introduced. Developments in bulk HTS rotating machines in other research groups are also summarized. The key issues of bulk HTS machines, including material progress of bulk HTS, in situ magnetization, and cooling together with AC loss at low-temperature operation are discussed.

The present status of the high temperature superconducting Maglev vehicle in China

NASA Astrophysics Data System (ADS)

Wang, J. S.; Wang, S. Y.; Zeng, Y. W.; Deng, C. Y.; Ren, Z. Y.; Wang, X. R.; Song, H. H.; Wang, X. Z.; Zheng, J.; Zhao, Y.

2005-02-01

Since the first successful running of the people-carrying high temperature superconducting (HTS) Maglev test vehicle on 31 December 2000, about 27 000 people have taken it, and the accumulated running distance is about 400 km. The levitation force of the onboard HTS equipment is measured periodically, and new experimental results measured on 5 March 2003 show that the performance of the onboard HTS Maglev equipment is almost the same as that of two years ago. Experimental results indicate that the long-term stability of the HTS Maglev vehicle is good. This further proves the feasibility of the HTS Maglev vehicle for practical transportation. It is worth mentioning that all the results are measured at a low speed; however, investigations of the dynamic performance of the HTS Maglev vehicle at high speed are necessary for practical application. Research on the dynamic performance of the HTS Maglev vehicle is ongoing.

Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Tigelaar, Dean M.

2009-01-01

Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

High hardness and superlative oxidation resistance in a pseudo-icosahehdral Cr-Al binary

NASA Astrophysics Data System (ADS)

Simonson, J. W.; Rosa, R.; Antonacci, A. K.; He, H.; Bender, A. D.; Pabla, J.; Adrip, W.; McNally, D. E.; Zebro, A.; Kamenov, P.; Geschwind, G.; Ghose, S.; Dooryhee, E.; Ibrahim, A.; Aronson, M. C.

Improving the efficiency of fossil fuel plants is a practical option for decreasing carbon dioxide emissions from electrical power generation. Present limits on the operating temperatures of exposed steel components, however, restrict steam temperatures and therefore energy efficiency. Even as a new generation of creep-resistant, high strength steels retain long term structural stability to temperatures as high as ~ 973 K, the low Cr-content of these alloys hinders their oxidation resistance, necessitating the development of new corrosion resistant coatings. We report here the nearly ideal properties of potential coating material Cr55Al229, which exhibits high hardness at room temperature as well as low thermal conductivity and superlative oxidation resistance at 973 K, with an oxidation rate at least three times smaller than those of benchmark materials. These properties originate from a pseudo-icosahedral crystal structure, suggesting new criteria for future research.

Simple approach to superhydrophobic nanostructured Al for practical antifrosting application based on enhanced self-propelled jumping droplets.

PubMed

Kim, Aeree; Lee, Chan; Kim, Hyungmo; Kim, Joonwon

2015-04-08

Frost formation can cause operational difficulty and efficiency loss for many facilities such as aircraft, wind turbines, and outdoor heat exchangers. Self-propelled jumping by condensate droplets on superhydrophobic surfaces delays frost formation, so many attempts have been made to exploit this phenomenon. However, practical application of this phenomenon is currently unfeasible because many processes to fabricate the superhydrophobic surfaces are inefficient and because self-propelled jumping is difficult to be achieved in a humid and low-temperature environment because superhydrophobicity is degraded in these conditions. Here, we achieved significantly effective anti-icing superhydrophobic aluminum. Its extremely low adhesive properties allow self-propelled jumping under highly supersaturated conditions of high humidity or low surface temperature. As a result, this surface helps retard frost formation at that condition. The aluminum was made superhydrophobic by a simple and cost-effective process that is adaptable to any shape. Therefore, it has promise for use in practical and industrial applications.

Effect of in-house chicken litter composting on ammonia and nitrous oxide emissions and pathogen reduction

USDA-ARS?s Scientific Manuscript database

Inhouse composting is a management practice to reduce pathogen in poultry litter. In between flocks, growers windrow the litter inside the broiler houses. This results in high temperatures that can reduce some pathogens in the litter. However, this practice is likely to increase emissions of NH3 and...

Cotton Physiological Responses to Application of Urea with NBPT and DCD Under Normal and High Temperature Conditions

USDA-ARS?s Scientific Manuscript database

Nitrogen fertilization is one the most expensive agricultural practices and crops are known to recover only about a third of the N fertilizer applied. A practice commonly recommended to improve N use efficiency is the incorporation of urease and/or nitrification inhibitor into N fertilizers. The ob...

Thermodynamic Temperature of High-Temperature Fixed Points Traceable to Blackbody Radiation and Synchrotron Radiation

NASA Astrophysics Data System (ADS)

Wähmer, M.; Anhalt, K.; Hollandt, J.; Klein, R.; Taubert, R. D.; Thornagel, R.; Ulm, G.; Gavrilov, V.; Grigoryeva, I.; Khlevnoy, B.; Sapritsky, V.

2017-10-01

Absolute spectral radiometry is currently the only established primary thermometric method for the temperature range above 1300 K. Up to now, the ongoing improvements of high-temperature fixed points and their formal implementation into an improved temperature scale with the mise en pratique for the definition of the kelvin, rely solely on single-wavelength absolute radiometry traceable to the cryogenic radiometer. Two alternative primary thermometric methods, yielding comparable or possibly even smaller uncertainties, have been proposed in the literature. They use ratios of irradiances to determine the thermodynamic temperature traceable to blackbody radiation and synchrotron radiation. At PTB, a project has been established in cooperation with VNIIOFI to use, for the first time, all three methods simultaneously for the determination of the phase transition temperatures of high-temperature fixed points. For this, a dedicated four-wavelengths ratio filter radiometer was developed. With all three thermometric methods performed independently and in parallel, we aim to compare the potential and practical limitations of all three methods, disclose possibly undetected systematic effects of each method and thereby confirm or improve the previous measurements traceable to the cryogenic radiometer. This will give further and independent confidence in the thermodynamic temperature determination of the high-temperature fixed point's phase transitions.

Room temperature giant and linear magnetoresistance in topological insulator Bi2Te3 nanosheets.

PubMed

Wang, Xiaolin; Du, Yi; Dou, Shixue; Zhang, Chao

2012-06-29

Topological insulators, a new class of condensed matter having bulk insulating states and gapless metallic surface states, have demonstrated fascinating quantum effects. However, the potential practical applications of the topological insulators are still under exploration worldwide. We demonstrate that nanosheets of a Bi(2)Te(3) topological insulator several quintuple layers thick display giant and linear magnetoresistance. The giant and linear magnetoresistance achieved is as high as over 600% at room temperature, with a trend towards further increase at higher temperatures, as well as being weakly temperature-dependent and linear with the field, without any sign of saturation at measured fields up to 13 T. Furthermore, we observed a magnetic field induced gap below 10 K. The observation of giant and linear magnetoresistance paves the way for 3D topological insulators to be useful for practical applications in magnetoelectronic sensors such as disk reading heads, mechatronics, and other multifunctional electromagnetic applications.

Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks.

PubMed

Fan, Guangwen; Shen, Yu; Hao, Xiaowei; Yuan, Zongming; Zhou, Zhi

2015-09-18

Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG) storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications.

The gallium melting-point standard: its role in our temperature measurement system.

PubMed

Mangum, B W

1977-01-01

The latest internationally-adopted temperature scale, the International Practical Temperature Scale of 1968 (amended edition of 1975), is discussed in some detail and a brief description is given of its evolution. The melting point of high-purity gallium (stated to be at least 99.99999% pure) as a secondary temperature reference point is evaluated. I believe that this melting-point temperature of gallium should be adopted by the various medical professional societies and voluntary standards groups as the reaction temperature for enzyme reference methods in clinical enzymology. Gallium melting-point cells are available at the National Bureau of Standards as Standard Reference Material No. 1968.

Low-Temperature Reactivities of Ultra-High Temperature Ceramics (Hf-X System)

DTIC Science & Technology

2005-12-01

as interacting fillers with the preceramic polymer formulations. In situ formation of the SiC phase was also evaluated as a practical approach in...led to a renewal of activities to fabricate MB2/ SiC composites as the materials of choice, because of their high thermal and oxidation resistance...HfB2/ SiC composite microstructures (and also HfC, ZrB2, and ZrC composites ) under pressureless conditions. These can be employed in reactive and

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

Bouchard, P.J.

A forthcoming revision to the R6 Leak-before-Break Assessment Procedure is briefly described. Practical application of the LbB concepts to safety-critical nuclear plant is illustrated by examples covering both low temperature and high temperature (>450{degrees}C) operating regimes. The examples highlight a number of issues which can make the development of a satisfactory LbB case problematic: for example, coping with highly loaded components, methodology assumptions and the definition of margins, the effect of crack closure owing to weld residual stresses, complex thermal stress fields or primary bending fields, the treatment of locally high stresses at crack intersections with free surfaces, the choicemore » of local limit load solution when predicting ligament breakthrough, and the scope of calculations required to support even a simplified LbB case for high temperature steam pipe-work systems.« less

Thermoregulatory responses and hydration practices in heat-acclimatized adolescents during preseason high school football.

PubMed

Yeargin, Susan Walker; Casa, Douglas J; Judelson, Daniel A; McDermott, Brendon P; Ganio, Matthew S; Lee, Elaine C; Lopez, Rebecca M; Stearns, Rebecca L; Anderson, Jeffrey M; Armstrong, Lawrence E; Kraemer, William J; Maresh, Carl M

2010-01-01

Previous researchers have not investigated the thermoregulatory responses to multiple consecutive days of American football in adolescents. To examine the thermoregulatory and hydration responses of high school players during formal preseason football practices. Observational study. Players practiced outdoors in late August once per day on days 1 through 5, twice per day on days 6 and 7, and once per day on days 8 through 10. Maximum wet bulb globe temperature averaged 23 +/- 4 degrees C. Twenty-five heat-acclimatized adolescent boys (age = 15 +/- 1 years, height = 180 +/- 8 cm, mass = 81.4 +/- 15.8 kg, body fat = 12 +/- 5%, Tanner stage = 4 +/- 1). We observed participants within and across preseason practices of football. Measures included gastrointestinal temperature (T(GI)), urine osmolality, sweat rate, forearm sweat composition, fluid consumption, testosterone to cortisol ratio, perceptual measures of thirst, perceptual measures of thermal sensation, a modified Environmental Symptoms Questionnaire, and knowledge questionnaires assessing the participants' understanding of heat illnesses and hydration. Results were analyzed for differences across time and were compared between younger (14-15 years, n = 13) and older (16-17 years, n = 12) participants. Maximum daily T(GI) values remained less than 40 degrees C and were correlated with maximum wet bulb globe temperature (r = 0.59, P = .009). Average urine osmolality indicated that participants generally experienced minimal to moderate hypohydration before (881 +/- 285 mOsmol/kg) and after (856 +/- 259 mOsmol/kg) each practice as a result of replacing approximately two-thirds of their sweat losses during exercise but inadequately rehydrating between practices. Age did not affect most variables; however, sweat rate was lower in younger participants (0.6 +/- 0.2 L/h) than in older participants (0.8 +/- 0.1 L/h) (F(1,18) = 8.774, P = .008). Previously heat-acclimatized adolescent boys (T(GI) < 40 degrees C) can safely complete the initial days of preseason football practice in moderate environmental conditions using well-designed practice guidelines. Adolescent boys replaced most sweat lost during practice but remained mildly hypohydrated throughout data collection, indicating inadequate hydration habits when they were not at practice.

Temperature and heat flux measurements: Challenges for high temperature aerospace application

NASA Technical Reports Server (NTRS)

Neumann, Richard D.

1992-01-01

The measurement of high temperatures and the influence of heat transfer data is not strictly a problem of either the high temperatures involved or the level of the heating rates to be measured at those high temperatures. It is a problem of duration during which measurements are made and the nature of the materials in which the measurements are made. Thermal measurement techniques for each application must respect and work with the unique features of that application. Six challenges in the development of measurement technology are discussed: (1) to capture the character and localized peak values within highly nonuniform heating regions; (2) to manage large volumes of thermal instrumentation in order to efficiently derive critical information; (3) to accommodate thermal sensors into practical flight structures; (4) to broaden the capabilities of thermal survey techniques to replace discrete gages in flight and on the ground; (5) to provide supporting instrumentation conduits which connect the measurement points to the thermally controlled data acquisition system; and (6) to develop a class of 'vehicle tending' thermal sensors to assure the integrity of flight vehicles in an efficient manner.

System for the growth of bulk SiC crystals by modified CVD techniques

NASA Technical Reports Server (NTRS)

Steckl, Andrew J.

1994-01-01

The goal of this program was the development of a SiC CVD growth of films thick enough to be useful as pseudo-substrates. The cold-walled CVD system was designed, assembled, and tested. Extrapolating from preliminary evaluation of SiC films grown in the system at relatively low temperatures indicates that the growth rate at the final temperatures will be high enough to make our approach practical. Modifications of the system to allow high temperature growth and cleaner growth conditions are in progress. This program was jointly funded by Wright Laboratory, Materials Directorate and NASA LeRC and monitored by NASA.

Semiconductor diode laser material and devices with emission in visible region of the spectrum

NASA Technical Reports Server (NTRS)

Ladany, I.; Kressel, H.

1975-01-01

Two alloy systems, (AlGa)As and (InGa)P, were studied for their properties relevant to obtaining laser diode operation in the visible region of the spectrum. (AlGa)As was prepared by liquid-phase epitaxy (LPE) and (InGa)P was prepared both by vapor-phase epitaxy and by liquid-phase epitaxy. Various schemes for LPE growth were applied to (InGa)P, one of which was found to be capable of producing device material. All the InGaP device work was done using vapor-phase epitaxy. The most successful devices were fabricated in (AlGa)As using heterojunction structures. At room temperature, the large optical cavity design yielded devices lasing in the red (7000 A). Because of the relatively high threshold due to the basic band structure limitation in this alloy, practical laser diode operation is presently limited to about 7300 A. At liquid-nitrogen temperature, practical continuous-wave operation was obtained at a wavelength of 6500 to 6600 A, with power emission in excess of 50 mW. The lowest pulsed lasing wavelength is 6280 A. At 223 K, lasing was obtained at 6770 A, but with high threshold currents. The work dealing with CW operation at room temperature was successful with practical operation having been achieved to about 7800 A.

Optimum dietary arginine:lysine ratio for broiler chickens is altered during heat stress in association with changes in intestinal uptake and dietary sodium chloride.

PubMed

Brake, J; Balnave, D; Dibner, J J

1998-12-01

1. The effects of varying the dietary arginine:lysine (Arg:Lys) ratio for broiler chickens at thermoneutral and high temperatures was studied in a series of 5 experiments which measured intestinal epithelial transport or evaluated growth and food efficiency with practical diets or diets supplemented with L-arginine free base. 2. The growth studies showed that increasing the Arg:Lys ratio at high temperatures produced consistent improvements in food conversion without any loss in growth. 3. Increasing dietary sodium chloride concentration reduced the Arg:Lys ratio necessary for optimum food conversion. 4. Food conversion responses were improved whether L-arginine free base was used as a dietary supplement in place of an inert filler or practical diets with differing ingredients were used to vary the Arg:Lys ratio. 5. In the presence of an equimolar concentration of lysine the uptake of arginine by the intestinal epithelium of heat-stressed broilers was reduced significantly compared with that of broilers at thermoneutral temperatures. 6. The results indicate that the ideal amino acid balance for broilers varies with ambient temperature.

Luminosity and cooling of highly magnetized white dwarfs: suppression of luminosity by strong magnetic fields

NASA Astrophysics Data System (ADS)

Bhattacharya, Mukul; Mukhopadhyay, Banibrata; Mukerjee, Subroto

2018-06-01

We investigate the luminosity and cooling of highly magnetized white dwarfs with electron-degenerate cores and non-degenerate surface layers where cooling occurs by diffusion of photons. We find the temperature and density profiles in the surface layers or envelope of white dwarfs by solving the magnetostatic equilibrium and photon diffusion equations in a Newtonian framework. We also obtain the properties of white dwarfs at the core-envelope interface, when the core is assumed to be practically isothermal. With the increase in magnetic field, the interface temperature increases whereas the interface radius decreases. For a given age of the white dwarf and for fixed interface radius or interface temperature, we find that the luminosity decreases significantly from about 10-6 to 10-9 L⊙ as the magnetic field strength increases from about 109 to 1012 G at the interface and hence the envelope. This is remarkable because it argues that magnetized white dwarfs are fainter and can be practically hidden in an observed Hertzsprung-Russell diagram. We also find the cooling rates corresponding to these luminosities. Interestingly, the decrease in temperature with time, for the fields under consideration, is not found to be appreciable.

Low Temperature Rhombohedral Single Crystal SiGe Epitaxy on c-plane Sapphire

NASA Technical Reports Server (NTRS)

Duzik, Adam J.; Choi, Sang H.

2016-01-01

Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (Al2O3) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100 C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550 C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

Genome-wide identification of genes involved in growth and fermentation activity at low temperature in Saccharomyces cerevisiae.

PubMed

Salvadó, Zoel; Ramos-Alonso, Lucía; Tronchoni, Jordi; Penacho, Vanessa; García-Ríos, Estéfani; Morales, Pilar; Gonzalez, Ramon; Guillamón, José Manuel

2016-11-07

Fermentation at low temperatures is one of the most popular current winemaking practices because of its reported positive impact on the aromatic profile of wines. However, low temperature is an additional hurdle to develop Saccharomyces cerevisiae wine yeasts, which are already stressed by high osmotic pressure, low pH and poor availability of nitrogen sources in grape must. Understanding the mechanisms of adaptation of S. cerevisiae to fermentation at low temperature would help to design strategies for process management, and to select and improve wine yeast strains specifically adapted to this winemaking practice. The problem has been addressed by several approaches in recent years, including transcriptomic and other high-throughput strategies. In this work we used a genome-wide screening of S. cerevisiae diploid mutant strain collections to identify genes that potentially contribute to adaptation to low temperature fermentation conditions. Candidate genes, impaired for growth at low temperatures (12°C and 18°C), but not at a permissive temperature (28°C), were deleted in an industrial homozygous genetic background, wine yeast strain FX10, in both heterozygosis and homozygosis. Some candidate genes were required for growth at low temperatures only in the laboratory yeast genetic background, but not in FX10 (namely the genes involved in aromatic amino acid biosynthesis). Other genes related to ribosome biosynthesis (SNU66 and PAP2) were required for low-temperature fermentation of synthetic must (SM) in the industrial genetic background. This result coincides with our previous findings about translation efficiency with the fitness of different wine yeast strains at low temperature. Copyright © 2016 Elsevier B.V. All rights reserved.

Multiwavelength Thermometry at High Temperature: Why It is Advantageous to Work in the Ultraviolet

NASA Astrophysics Data System (ADS)

Girard, F.; Battuello, M.; Florio, M.

2014-07-01

In principle, multiwavelength radiation thermometry allows one to correctly measure the temperature of surfaces of unknown and varying surface emissivity. Unfortunately, none of the practical realizations proposed in the past proved to be sufficiently reliable because of a strong influence of the errors arising from incorrect modeling of the emissivity and of the limited number of operating wavelengths. The use of array detectors allows a high degree of flexibility both in terms of number and spectral position of the working wavelength bands. In the case of applications at high temperatures, i.e., near 2000 C or above, an analysis of the theoretical measuring principles of multiwavelength thermometry, suggests the opportunity of investigating the possible advantages in extending the operating wavelengths toward the ultraviolet region. To this purpose, a simulation program was developed which allows investigation of the effect of different influencing parameters. This paper presents a brief theoretical introduction and practical analysis of the method. The best choices are derived in terms of the different influencing parameters and data relative to the simulation of both real materials and fictitious emissivity curves and have been studied and analyzed with different emissivity models to check the robustness of the method.

Non-contact temperature Raman measurement in YSZ and alumina ceramics

NASA Astrophysics Data System (ADS)

Thapa, Juddha; Chorpening, Benjamin T.; Buric, Michael P.

2018-02-01

Yttria-stabilized zirconia (YSZ: ZrO2 + Y2O3) and alumina (Al2O3) are widely used in high-temperature applications due to their high-temperature stability, low thermal conductivity, and chemical inertness. Alumina is used extensively in engineered ceramic applications such as furnace tubes and thermocouple protection tubes, while YSZ is commonly used in thermal barrier coatings on turbine blades. Because they are already often found in high temperature and combustion applications, these two substances have been compared as candidates for Raman thermometry in high-temperature energy-related applications. Both ceramics were used with as-received rough surfaces, i.e., without polishing or modification. This closely approximates surface conditions in practical high-temperature situations. A single-line argon ion laser at 488nm was used to excite the materials inside a cylindrical furnace while measuring Raman spectra with a fixed-grating spectrometer. The shift in the peak positions of the most intense A1g peak at 418cm-1 (room temperature position) of alumina ceramic and relatively more symmetric Eg peak at 470cm-1 (room temperature position) of YSZ were measured and reported along with a thermocouple-derived reference temperature up to about 1000°C. This study showed that alumina and YSZ ceramics can be used in high-temperature Raman thermometry with an accuracy of 4.54°C and 10.5°C average standard deviations respectively over the range of about 1000°C. We hope that this result will guide future researchers in selecting materials and utilizing Raman non-contact temperature measurements in harsh environments.

Comparison of Oral and Axillary Temperatures in Intubated Pediatric Patients.

PubMed

Wood, Danielle; Heitschmidt, Mary; Fogg, Louis

2018-05-10

Accurate body temperature measurement is essential in providing timely care to critically ill patients. Current practice within the Pediatric ICU (PICU) at a Midwestern academic medical center is to obtain axillary temperatures in endotracheally intubated patients. According to research, axillary temperatures have greater variance than other forms of temperature measurement. Research in adult patients show that oral temperature measurement in endotracheally intubated patients is acceptable as the heated gases from the ventilator has no significant effect on measured temperatures. This study sought to determine if the same is true in pediatrics. Oral and axillary temperatures of endotracheally intubated pediatric patients were obtained during unit prescribed vital assessment intervals. Patients were divided into neonate, infant, and children age groups with 25 sets of temperatures obtained for each group. Descriptive statistics and Bland-Altman plot interpretation were performed to determine confidence intervals for each age group. Bland-Altman plot analysis of oral and axillary routes of temperature measurement showed a high positive correlation within all age groups studied. The infant age group showed lower correlation in comparison to neonates and children. The infant age group also had an outlier of data sets with lower oral temperatures as compared to the axilla. Oral temperature measurement is a viable alternative to axillary temperature measurement in endotracheally intubated pediatric patients. Correction factors for age groups were calculated for prediction of axillary temperature based on measured oral temperature. This study serves as evidence for practice change within the studied unit. Copyright © 2018. Published by Elsevier Inc.

Food safety practices among Norwegian consumers.

PubMed

Røssvoll, Elin Halbach; Lavik, Randi; Ueland, Øydis; Jacobsen, Eivind; Hagtvedt, Therese; Langsrud, Solveig

2013-11-01

An informed consumer can compensate for several potential food safety violations or contaminations that may occur earlier in the food production chain. However, a consumer can also destroy the work of others in the chain by poor food handling practices, e.g., by storing chilled ready-to-eat foods at abusive temperatures. To target risk-reducing strategies, consumer groups with high-risk behavior should be identified. The aim of this study was to identify demographic characteristics associated with high-risk food handling practices among Norwegian consumers. More than 2,000 randomly selected Norwegian consumers were surveyed, and the results were analyzed with a risk-based grading system, awarding demerit points for self-reported food safety violations. The violations were categorized into groups, and an ordinary multiple linear regression analysis was run on the summarized demerit score for each group and for the entire survey group as a whole. Young and elderly men were identified as the least informed consumer groups with the most unsafe practices regarding food safety. Single persons reported poorer practices than those in a relationship. People with higher education reported poorer practices than those with lower or no education, and those living in the capital of Norway (Oslo) reported following more unsafe food practices than people living elsewhere in Norway. Men reported poorer food safety practices than women in all categories with two exceptions: parboiling raw vegetables before consumption and knowledge of refrigerator temperature. These findings suggest that risk-reducing measures should target men, and a strategy is needed to change their behavior and attitudes.

Large-Scale Wireless Temperature Monitoring System for Liquefied Petroleum Gas Storage Tanks

PubMed Central

Fan, Guangwen; Shen, Yu; Hao, Xiaowei; Yuan, Zongming; Zhou, Zhi

2015-01-01

Temperature distribution is a critical indicator of the health condition for Liquefied Petroleum Gas (LPG) storage tanks. In this paper, we present a large-scale wireless temperature monitoring system to evaluate the safety of LPG storage tanks. The system includes wireless sensors networks, high temperature fiber-optic sensors, and monitoring software. Finally, a case study on real-world LPG storage tanks proves the feasibility of the system. The unique features of wireless transmission, automatic data acquisition and management, local and remote access make the developed system a good alternative for temperature monitoring of LPG storage tanks in practical applications. PMID:26393596

Practical considerations for solar energy thermally enhanced photo-luminescence (TEPL) (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kruger, Nimrod; Manor, Assaf; Kurtulik, Matej; Sabapathy, Tamilarasan; Rotschild, Carmel

2017-04-01

While single-junction photovoltaics (PV's) are considered limited in conversion efficiency according to the Shockley-Queisser limit, concepts such as solar thermo-photovoltaics aim to harness lost heat and overcome this barrier. We claim the novel concept of Thermally Enhanced Photoluminescence (TEPL) as an easier route to achieve this goal. Here we present a practical TEPL device where a thermally insulated photo-luminescent (PL) absorber, acts as a mediator between a photovoltaic cell and the sun. This high temperature absorber emits blue-shifted PL at constant flux, then coupled to a high band gap PV cell. This scheme promotes PV conversion efficiencies, under ideal conditions, higher than 62% at temperatures lower than 1300K. Moreover, for a PV and absorber band-gaps of 1.45eV (GaAs PV's) and 1.1eV respectively, under practical conditions, solar concentration of 1000 suns, and moderate thermal insulation; the conversion efficiencies potentially exceed 46%. Some of these practical conditions belong to the realm of optical design; including high photon recycling (PR) and absorber external quantum efficiency (EQE). High EQE values, a product of the internal QE of the active PL materials and the extraction efficiency of each photon (determined by the absorber geometry and interfaces), have successfully been reached by experts in laser cooling technology. PR is the part of emitted low energy photons (in relation to the PV band-gap) that are reabsorbed and consequently reemitted with above band-gap energies. PV back-reflector reflectivity, also successfully achieved by those who design the cutting edge high efficiency PV cells, plays a major role here.

Two-way shape memory behavior of semi-crystalline elastomer under stress-free condition

NASA Astrophysics Data System (ADS)

Qian, Chen; Dong, Yubing; Zhu, Yaofeng; Fu, Yaqin

2016-08-01

Semi-crystalline shape memory polymers exhibit two-way shape memory effect (2W-SME) under constant stresses through crystallization-induced elongation upon cooling and melting-induced constriction upon heating. The applied constant stress influenced the prediction and usability of 2W-SME in practical applications without any external force. Here the reversible shape transition in EVA-shaped memory polymer was quantitative analyzed under a suitable temperature range and external stress-free condition. The fraction of reversible strain increased with increasing upper temperature (T high) within the temperature range and reached the maximum value of 13.62% at 70 °C. However, reversible strain transition was almost lost when T high exceeded 80 °C because of complete melting of crystalline scaffold, known as the latent recrystallization template. The non-isothermal annealing of EVA 2W-SMP under changing circulating temperatures was confirmed. Moreover, the orientation of crystallization was retained at high temperatures. These findings may contribute to design an appropriate shape memory protocol based on application-specific requirements.

Ultrahigh vacuum and low-temperature cleaning of oxide surfaces using a low-concentration ozone beam

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

Pratt, A.; Department of Physics, University of York, Heslington, York YO10 5DD; Graziosi, P.

We present a novel method of delivering a low-concentration (<15%) ozone beam to an ultra-high vacuum environment for the purpose of cleaning and dosing experimental samples through oxidation processing. The system described is safe, low-cost, and practical and overcomes the limitations of ozone transport in the molecular flow environment of high or ultrahigh vacuum whilst circumventing the use of pure ozone gas which is potentially highly explosive. The effectiveness of this method in removing surface contamination is demonstrated through comparison of high-temperature annealing of a simple oxide (MgO) in ozone and oxygen environments as monitored using quadrupole mass spectroscopy andmore » Auger electron spectroscopy. Additionally, we demonstrate the potential of ozone for obtaining clean complex oxide surfaces without the need for high-temperature annealing which may significantly alter surface structure.« less

The Quechua manta pouch: a caretaking practice for buffering the Peruvian infant against the multiple stressors of high altitude.

PubMed

Tronick, E Z; Thomas, R B; Daltabuit, M

1994-08-01

The manta pouch--a caretaking practice of tightly swaddling and enclosing the infant in a set of cloths and blankets--and other caretaking practices are described for high-altitude resident (> 4,000 m) Quechua mother-infant pairs (N = 14). The manta pouch modifies the microenvironment inside the pouch so that, compared to the ambient environment, the temperature is higher and more stable, the humidity is higher, the partial pressure of O2 is lower, and stimulation levels are reduced. As the infant gets older, the characteristics of the pouch are modified such that the infant is increasingly exposed to ambient conditions. These caretaking practices may benefit the infant by buffering the infant from the multiple ecological stressors of high altitude, but they may also incur costs by exposing the infant to additional microenvironmental stressors (e.g., higher CO2 levels) and by reducing stimulation and limiting infant movement.

Low-Temperature Growth of Two-Dimensional Layered Chalcogenide Crystals on Liquid.

PubMed

Zhou, Yubing; Deng, Bing; Zhou, Yu; Ren, Xibiao; Yin, Jianbo; Jin, Chuanhong; Liu, Zhongfan; Peng, Hailin

2016-03-09

The growth of high-quality two-dimensional (2D) layered chalcogenide crystals is highly important for practical applications in future electronics, optoelectronics, and photonics. Current route for the synthesis of 2D chalcogenide crystals by vapor deposition method mainly involves an energy intensive high-temperature growth process on solid substrates, often suffering from inhomogeneous nucleation density and grain size distribution. Here, we first demonstrate a facile vapor-phase synthesis of large-area high-quality 2D layered chalcogenide crystals on liquid metal surface with relatively low surface energy at a growth temperature as low as ∼100 °C. Uniform and large-domain-sized 2D crystals of GaSe and GaxIn1-xSe were grown on liquid metal surface even supported on a polyimide film. As-grown 2D GaSe crystals have been fabricated to flexible photodetectors, showing high photoresponse and excellent flexibility. Our strategy of energy-sustainable low-temperature growth on liquid metal surface may open a route to the synthesis of high-quality 2D crystals of Ga-, In-, Bi-, Hg-, Pb-, or Sn-based chalcogenides and halides.

78 FR 65306 - Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-31

... Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams AGENCY: Environmental... Monitoring of Temperature and Flow in Wadeable Streams'' (EPA/600/R-13/170). The EPA also is announcing that... Development. The report describes best practices for the deployment of continuous temperature and flow sensors...

An experimental study of the atmospheric boundary layer modified by a change in surface roughness and surface temperature

NASA Technical Reports Server (NTRS)

Tieleman, H. W.; Derrington, D. B., Jr.

1977-01-01

Turbulent flow, resembling an on-shore flow from the ocean crossing the beach at an oblique angle, is investigated. Measurements of this flow have been taken at high sample rates and include measurements at various heights, high enough to describe the portion of the mean wind and temperature profiles and fluxes that are of interest for the solution of practical engineering problems. These problems could include air pollution (fumigation and plume trapping), operation of low flying aircraft, crop-spraying and crop-dusting operations.

A systematic study of atmospheric pressure chemical vapor deposition growth of large-area monolayer graphene.

PubMed

Liu, Lixin; Zhou, Hailong; Cheng, Rui; Chen, Yu; Lin, Yung-Chen; Qu, Yongquan; Bai, Jingwei; Ivanov, Ivan A; Liu, Gang; Huang, Yu; Duan, Xiangfeng

2012-01-28

Graphene has attracted considerable interest as a potential material for future electronics. Although mechanical peel is known to produce high quality graphene flakes, practical applications require continuous graphene layers over a large area. The catalyst-assisted chemical vapor deposition (CVD) is a promising synthetic method to deliver wafer-sized graphene. Here we present a systematic study on the nucleation and growth of crystallized graphene domains in an atmospheric pressure chemical vapor deposition (APCVD) process. Parametric studies show that the mean size of the graphene domains increases with increasing growth temperature and CH 4 partial pressure, while the density of domains decreases with increasing growth temperature and is independent of the CH 4 partial pressure. Our studies show that nucleation of graphene domains on copper substrate is highly dependent on the initial annealing temperature. A two-step synthetic process with higher initial annealing temperature but lower growth temperature is developed to reduce domain density and achieve high quality full-surface coverage of monolayer graphene films. Electrical transport measurements demonstrate that the resulting graphene exhibits a high carrier mobility of up to 3000 cm 2 V -1 s -1 at room temperature.

A Theoretical Model for Predicting Fracture Strength and Critical Flaw Size of the ZrB2-ZrC Composites at High Temperatures

NASA Astrophysics Data System (ADS)

Wang, Ruzhuan; Li, Xiaobo; Wang, Jing; Jia, Bi; Li, Weiguo

2018-06-01

This work shows a new rational theoretical model for quantitatively predicting fracture strength and critical flaw size of the ZrB2-ZrC composites at different temperatures, which is based on a new proposed temperature dependent fracture surface energy model and the Griffith criterion. The fracture model takes into account the combined effects of temperature and damage terms (surface flaws and internal flaws) with no any fitting parameters. The predictions of fracture strength and critical flaw size of the ZrB2-ZrC composites at high temperatures agree well with experimental data. Then using the theoretical method, the improvement and design of materials are proposed. The proposed model can be used to predict the fracture strength, find the critical flaw and study the effects of microstructures on the fracture mechanism of the ZrB2-ZrC composites at high temperatures, which thus could become a potential convenient, practical and economical technical means for predicting fracture properties and material design.

Interactions of CO2, temperature and management practices: simulations with a modified version of CERES-Wheat

NASA Technical Reports Server (NTRS)

Tubiello, F. N.; Rosenzweig, C.; Volk, T.

1995-01-01

A new growth subroutine was developed for CERES-Wheat, a computer model of wheat (Triticum aestivum) growth and development. The new subroutine simulates canopy photosynthetic response to CO2 concentrations and light levels, and includes the effects of temperature on canopy light-use efficiency. Its performance was compared to the original CERES-Wheat V-2 10 in 30 different cases. Biomass and yield predictions of the two models were well correlated (correlation coefficient r > 0.95). As an application, summer growth of spring wheat was simulated at one site. Modeled crop responses to higher mean temperatures, different amounts of minimum and maximum warming, and doubled CO2 concentrations were compared to observations. The importance of irrigation and nitrogen fertilization in modulating the wheat crop climatic responses were also analyzed. Specifically, in agreement with observations, rainfed crops were found to be more sensitive to CO2 increases than irrigated ones. On the other hand, low nitrogen applications depressed the ability of the wheat crop to respond positively to CO2 increases. In general, the positive effects of high CO2 on grain yield were found to be almost completely counterbalanced by the negative effects of high temperatures. Depending on how temperature minima and maxima were increased, yield changes averaged across management practices ranged from -4% to 8%.

Temperature, Sowing and Harvest Dates, and Yield of Maize in the Southwestern US

NASA Astrophysics Data System (ADS)

Kafatos, M.; Stack, D.; Myoung, B.; Kim, S. H.; Kim, J.

2014-12-01

Since sowing date of maize is sensitive to climate variability and changes, it is of a practical importance to examine how sowing dates affect maize yields in various temperature regimes in the southwestern US. A 21-year (1991-2011) simulation of maize yield using Agricultural Production Systems sIMulator (APSIM) with observed meteorological forcing, shows that earlier sowing dates are favorable for higher yields primarily by increasing the length of growing season in cold mountaineous regions. In these regions, warmer conditions in the sowing period tend to advance the sowing date and then enhance yield. Over low-elevation warm regions, yields are less correlated with sowing dates and the length of growing season, perhaps because growing season temperatures are high enough for fast growth. Instead, in the warm regions, maize yields are sensitive to temperature variations during the late growing season due to adverse effects of extreme high temperature events on maize development.

A new temperature profiling probe for investigating groundwater-surface water interaction

USGS Publications Warehouse

Naranjo, Ramon C.; Robert Turcotte,

2015-01-01

Measuring vertically nested temperatures at the streambed interface poses practical challenges that are addressed here with a new discrete subsurface temperature profiling probe. We describe a new temperature probe and its application for heat as a tracer investigations to demonstrate the probe's utility. Accuracy and response time of temperature measurements made at 6 discrete depths in the probe were analyzed in the laboratory using temperature bath experiments. We find the temperature probe to be an accurate and robust instrument that allows for easily installation and long-term monitoring in highly variable environments. Because the probe is inexpensive and versatile, it is useful for many environmental applications that require temperature data collection for periods of several months in environments that are difficult to access or require minimal disturbance.

High-Temperature Particulate Matter Filtration with Resilient Yttria-Stabilized ZrO2 Nanofiber Sponge.

PubMed

Wang, Haolun; Lin, Sen; Yang, Shen; Yang, Xudong; Song, Jianan; Wang, Dong; Wang, Haiyang; Liu, Zhenglian; Li, Bo; Fang, Minghao; Wang, Ning; Wu, Hui

2018-05-01

Particulate matter (PM) is a major air pollutant in many regions, jeopardizing ecosystems and public health. Filtration at pollutant source is one of the most important ways to protect the environment, however, considering the high-temperature exhaust gas emissions, effective removal of PM and related pollutants from their sources remains a major challenge. In this study, a resilient, heat-resisting, and high-efficiency PM filter based on yttria-stabilized ZrO 2 (YSZ) nanofiber sponge produced with a scalable solution blow spinning process is reported. The porous 3D sponge composed of YSZ nanofibers is lightweight (density of 20 mg cm -3 ) and resilient at both room temperature and high temperatures. At room-temperature conditions, the YSZ nanofiber sponge exhibits 99.4% filtration efficiency for aerosol particles with size in the range of 20-600 nm, associated with a low pressure drop of only 57 Pa under an airflow velocity of 4.8 cm s -1 . At a high temperature of 750 °C, the ceramic sponge maintains a high filtration efficiency of 99.97% for PM 0.3-2.5 under a high airflow velocity of 10 cm s -1 . A practical vehicle exhaust filter to capture particles with filtration efficiency of >98.3% is also assembled. Hence, the YSZ nanofiber sponge has enormous potential to be applied in industry. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experiment and simulation study on alkalis transfer characteristic during direct combustion utilization of bagasse.

PubMed

Liao, Yanfen; Cao, Yawen; Chen, Tuo; Ma, Xiaoqian

2015-10-01

Bagasse is utilized as fuel in the biggest biomass power plant of China, however, alkalis in the fuel created severe agglomeration and slagging problems. Alkalis transfer characteristic, agglomeration causes in engineering practice, additive improvement effects and mechanism during bagasse combustion were investigated via experiments and simulations. Only slight agglomeration occurs in ash higher than 800°C. Serious agglomeration in practical operation should be attributed to the gaseous alkalis evaporating at high temperature and condensing on the cooler grain surfaces in CFB. It can be speculated that ash caking can be avoided with temperature lower than 750°C and heating surface corrosion caused by alkali metal vapor can be alleviated with temperature lower than 850°C. Kaolin added into the bagasse has an apparent advantage over CaO additive both in enhancing ash fusion point and relieving alkali-chloride corrosion by locking alkalis in dystectic solid compounds over the whole temperature range. Copyright © 2015 Elsevier Ltd. All rights reserved.

Improving vaccination cold chain in the general practice setting.

PubMed

Page, Sue L; Earnest, Arul; Birden, Hudson; Deaker, Rachelle; Clark, Chris

2008-10-01

This study compared temperature control in different types of vaccine storing refrigerators in general practice and tested knowledge of general practice staff in vaccine storage requirements. Temperature data loggers were set to serially record the temperature within vaccine refrigerators in 28 general practices, recording at 12 minute intervals over a period of 10 days on each occasion. A survey of vaccine storage knowledge and records of divisions of general practice immunisation contacts were also obtained. There was a significant relationship between type of refrigerator and optimal temperature, with the odds ratio for bar style refrigerator being 0.005 (95% CI: 0.001-0.044) compared to the purpose built vaccine refrigerators. Score on a survey of vaccine storage was also positively associated with optimal storage temperature. General practices that invest in purpose built vaccine refrigerators will achieve standards of vaccine cold chain maintenance significantly more reliably than can be achieved through regular cold chain monitoring and practice supports.

Facile synthesis of a SiOx/asphalt membrane for high performance lithium-ion battery anodes.

PubMed

Xu, Quan; Sun, Jian-Kun; Li, Ge; Li, Jin-Yi; Yin, Ya-Xia; Guo, Yu-Guo

2017-11-07

Herein, a novel SiO x /asphalt membrane was facilely synthesized via demulsification of porous SiO x microspheres. After high temperature pyrolysis, SiO x /carbon composites not only could function as binder-free anodes, but could also exhibit excellent cycling stability and high initial Coulombic efficiency as anodes for practical application.

A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit.

PubMed

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Xiong, Jijun

2016-06-18

This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of -50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor's output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments.

A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit

PubMed Central

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Xiong, Jijun

2016-01-01

This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of −50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor’s output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments. PMID:27322288

Lattice dynamics and elasticity for ε-plutonium [First-principles lattice dynamics for ε-plutonium

DOE PAGES

Söderlind, Per

2017-04-25

Here, lattice dynamics and elasticity for the high-temperature ε phase (body-centered cubic; bcc) of plutonium is predicted utilizing first-principles electronic structure coupled with a self-consistent phonon method that takes phonon-phonon interaction and strong anharmonicity into account. These predictions establish the first sensible lattice-dynamics and elasticity data on ε-Pu. The atomic forces required for the phonon scheme are highly accurate and derived from the total energies obtained from relativistic and parameter-free density-functional theory. The results appear reasonable but no data exist to compare with except those from dynamical mean-field theory that suggest ε-plutonium is mechanically unstable. Fundamental knowledge and understanding ofmore » the high-temperature bcc phase, that is generally present in all actinide metals before melting, is critically important for a proper interpretation of the phase diagram as well as practical modeling of high-temperature properties.« less

Region of validity of the finite–temperature Thomas–Fermi model with respect to quantum and exchange corrections

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

Dyachkov, Sergey, E-mail: serj.dyachkov@gmail.com; Moscow Institute of Physics and Technology, 9 Institutskiy per., Dolgoprudny, Moscow Region 141700; Levashov, Pavel, E-mail: pasha@ihed.ras.ru

We determine the region of applicability of the finite–temperature Thomas–Fermi model and its thermal part with respect to quantum and exchange corrections. Very high accuracy of computations has been achieved by using a special approach for the solution of the boundary problem and numerical integration. We show that the thermal part of the model can be applied at lower temperatures than the full model. Also we offer simple approximations of the boundaries of validity for practical applications.

Fiber-optic temperature sensor using a spectrum-modulating semiconductor etalon

NASA Technical Reports Server (NTRS)

Beheim, Glenn; Anthan, Donald J.; Beheim, Glenn; Anthan, Donald J.

1987-01-01

Described is a fiber-optic temperature sensor that uses a spectrum modulating SiC etalon. The spectral output of this type of sensor may be analyzed to obtain a temperature measurement which is largely independent of the transmission properties of the sensor's fiber-optic link. A highly precise laboratory spectrometer is described in detail, and this instrument is used to study the properties of this type of sensor. Also described are a number of different spectrum analyzers that are more suitable for use in a practical thermometer.

Understanding Multiscale Surface Water-Groundwater Interactions on Scott River Watershed Temperatures with the use of Distributed Temperature Sensing (DTS) in Support of the Coldwater Salmonid Fishery Beneficial Use

NASA Astrophysics Data System (ADS)

Hines, R. J.; Harter, T.; Tyler, S. W.; McFadin, B.; Yokel, E.

2008-12-01

The Scott River is a major tributary to the Klamath River that provides cold water rearing habitat for wild salmonid populations, including coho salmon (Oncorhynchus kisutch), Chinook salmon (O. tshawytscha), and steelhead trout (O. mykiss). During the summer months (July through September), the main-stem Scott River becomes disconnected from its tributaries throughout much of Scott Valley and relies primarily on baseflow from the groundwater aquifer. Summer stream temperatures in the Scott River are currently at levels that are not considered sustainable for the native salmonid population, resulting in the enactment of a Total Maximum Daily Load (TMDL) for temperature. Two of the conditions affecting stream temperature have been identified as increases in solar radiation due to a reduction in riparian vegetation and decreased accretion of groundwater. In conjunction with a regional scale surface water-groundwater modeling effort to investigate the benefits of various conjunctive use management alternatives on mid- and late summer baseflow in the Scott River, we completed high-resolution field measurements of stream temperature over an approximately 1,050-meter reach. Temperatures were measured using Fiber-Optic Distributed Temperature Sensing (DTS) techniques. The DTS survey in combination with FLIR stream surface temperature data from 2003 indicate that groundwater discharge to the Scott River is highly localized throughout the valley. The results of the DTS survey depict highly localized areas of groundwater accretion, as well as prominent localized temperature effects from riparian vegetation and river geomorphology. While originally modeled as a well-mixed stream during FLIR analysis, the DTS data further suggest that locally strong, vertical thermal gradients are found near the bottom of the active stream channel. The high-resolution temperature measurements were paired with fish surveys in order to determine the correlation between areas of identified lower river temperatures, groundwater accretion and other beneficial salmonid habitat indicators. Our work suggests that understanding of local-scale groundwater-stream interaction and analysis of corresponding local-scale geologic and riparian vegetation controls are critical to understanding the basin-scale groundwater-stream interactions. Preliminary data reviews indicate that groundwater discharge leads to distinct cold temperature pools near the streambed, while the remainder of the stream column is thermally well mixed. This local-scale, three-dimensional understanding is necessary if strategies are to be developed that aim for effective water resource management practices and improved beneficial use habitat. A multi-scale field reconnaissance and modeling approach is suggested to develop water management practices that lead to better habitat protection throughout the watershed.

A Miniature Palladium-Iron Thermometer for Temperatures Down to 0.05 K

NASA Technical Reports Server (NTRS)

Tuttle, Jim; DiPirro, Michael; Canavan, Ed; Shirron, Peter; Kunes, Evan; Hait, Tom; Krebs, Carolyn (Technical Monitor)

2001-01-01

Magnetic thermometers are appealing at temperatures below about 0.1 Kelvin, because the avoid the noise self-heating problems associated with resistive thermometers. In practical, metallic dilute electronic thermometers add the advantages of chemical stability, high thermal conductivity, and easy in heat sinking work we describe a palladium-iron thermometer which was designed to be small and conveniently packaged and optimized for use at temperatures down to 0.05 Kelvin. The device showed Curie-Weiss behavior above about 0.06 Kelvin, and we achieve 41 nK/ square root of z temperature resolution at a temperature of 49 mK. We describe the design and operation of this thermometers and present the test results.

[A new non-contact method based on relative spectral intensity for determining junction temperature of LED].

PubMed

Qiu, Xi-Zhen; Zhang, Fang-Hui

2013-01-01

The high-power white LED was prepared based on the high thermal conductivity aluminum, blue chips and YAG phosphor. By studying the spectral of different junction temperature, we found that the radiation spectrum of white LED has a minimum at 485 nm. The radiation intensity at this wavelength and the junction temperature show a good linear relationship. The LED junction temperature was measured based on the formula of relative spectral intensity and junction temperature. The result measured by radiation intensity method was compared with the forward voltage method and spectral method. The experiment results reveal that the junction temperature measured by this method was no more than 2 degrees C compared with the forward voltage method. It maintains the accuracy of the forward voltage method and overcomes the small spectral shift of spectral method, which brings the shortcoming on the results. It also had the advantages of practical, efficient and intuitive, noncontact measurement, and non-destruction to the lamp structure.

High-speed highly temperature stable 980 nm VCSELs operating at 25 Gb/s at up to 85 °C for short reach optical interconnects

NASA Astrophysics Data System (ADS)

Mutig, Alex; Lott, James A.; Blokhin, Sergey A.; Moser, Philip; Wolf, Philip; Hofmann, Werner; Nadtochiy, Alexey M.; Bimberg, Dieter

2011-03-01

The progressive penetration of optical communication links into traditional copper interconnect markets greatly expands the applications of vertical cavity surface emitting lasers (VCSELs) for the next-generation of board-to-board, moduleto- module, chip-to-chip, and on-chip optical interconnects. Stability of the VCSEL parameters at high temperatures is indispensable for such applications, since these lasers typically reside directly on or near integrated circuit chips. Here we present 980 nm oxide-confined VCSELs operating error-free at bit rates up to 25 Gbit/s at temperatures as high as 85 °C without adjustment of the drive current and peak-to-peak modulation voltage. The driver design is therefore simplified and the power consumption of the driver electronics is lowered, reducing the production and operational costs. Small and large signal modulation experiments at various temperatures from 20 up to 85 °C for lasers with different oxide aperture diameters are presented in order to analyze the physical processes controlling the performance of the VCSELs. Temperature insensitive maximum -3 dB bandwidths of around 13-15 GHz for VCSELs with aperture diameters of 10 μm and corresponding parasitic cut-off frequencies exceeding 22 GHz are observed. Presented results demonstrate the suitability of our VCSELs for practical high speed and high temperature stable short-reach optical links.

Impact of detergent systems on bacterial survival on laundered fabrics.

PubMed Central

Jaska, J M; Fredell, D L

1980-01-01

The survival of Staphylococcus aureus was determined from inoculated swatches laundered in either a phosphate or a phosphate-substitute detergent. In a Plackett-Burman design study, the independent variables of detergent type, concentration, and variation, wash water temperature, soil load, cycle time, and water hardness were assigned high and low values. Wash water temperatures of 27, 38, 49, and 60 degrees C were employed. Viable bacteria were recovered from macerated swatches. Statistical analysis disclosed that there was no practical difference in the ability of phosphate or phosphate-substitute detergents to reduce the level of S. aureus on the laundered swatches in this controlled design. Analysis did reveal that water temperature was the most significant independent variables. The remaining variables did not appear to have any practical significance upon bacterial reduction. This bacteriological study did not evaluate other essential detergent properties. PMID:7377775

Thermal effects on fish ecology

USGS Publications Warehouse

Coutant, Charles C.

1976-01-01

Of all the environmental factors that influence aquatic organisms, temperature is the most all-pervasive. There is always an environmental temperature while other factors may or may not be present to exert their effects. Fish are, for all practical purposes, thermal conformers, or obligate poikilotherms. That is, they are able to exert little significant influence on maintaining a certain body temperature by specialized metabolic or behavioral means. Their body temperature thus fluctuates nearly in concert with the temperature of their aquatic medium (although particularly large, actively-moving fish such as tuna have deep muscle temperatures slightly higher than the water). Intimate contact at the gills of body fluids with the outside water and the high specific heat of water provide a very efficient heat exchanger that insures this near identity of internal and external temperatures.

Effect of annealing on optical properties and structure of the vanadium dioxide thin films

NASA Astrophysics Data System (ADS)

Zhu, Huiqun; Li, Yi; Li, Yuming; Huang, Yize; Tong, Guoxiang; Fang, Baoying; Zheng, Qiuxin; Li, Liu; Shen, Yujian

2012-10-01

VO2 thin films were prepared on soda-lime glass substrates by DC magnetron sputtering at room temperature using vanadium target and post annealing in air. X-ray diffraction and FTIR spectroscopy analyses showed that the films obtained at the optimized parameters have high VO2 (011) orientation. Both low temperature deposition and post annealing method were beneficial to grow the nano-films with pure VO2 phase-structure and composition. Metalinsulator transition properties of the VO2 films in terms of infrared transmittance, transmittance variation and film thickness were investigated under varying annealing temperature. Results showed that infrared transmittance variation and transition temperature of the nano-films were significantly improved and reduced respectively. Therefore, this study was able to develop practical low-cost preparation methods for high-performance intelligent energy-saving thin films.

[Response of indica rice spikelet differentiation and degeneration to air temperature and solar radiation of different sowing dates].

PubMed

Wang, Ya Liang; Zhang, Yu Ping; Xiang, Jing; Wang, Lei; Chen, Hui Zhe; Zhang, Yi Kai; Zhang, Wen Qian; Zhu, De Feng

2017-11-01

In this study, three rice varieties, including three-line hybrid indica rice Wuyou308 and Tianyouhuazhan, and inbred indica rice Huanghuazhan were used to investigate the effects of air temperature and solar radiation on rice growth duration and spikelet differentiation and degeneration. Ten sowing-date treatments were conducted in this field experiment. The results showed that the growth duration of three indica rice varieties were more sensitive to air temperature than to day-length. With average temperature increase of 1 ℃, panicle initiation advanced 1.5 days, but the panicle growth duration had no significant correlation with the temperature and day-length. The number of spikelets and differentiated spikelets revealed significant differences among different sowing dates. Increases in average temperature, maximum temperature, minimum temperature, effective accumulated temperature, temperature gap and the solar radiation benefited dry matter accumulation and spikelet differentiation of all varieties. With increases of effective accumulated temperature, diurnal temperature gap and solar radiation by 50 ℃, 1 ℃, 50 MJ·m -2 during panicle initiation stage, the number of differentiated spikelets increased 10.5, 14.3, 17.1 respectively. The rate of degenerated spikelets had a quadratic correlation with air temperature, extreme high and low temperature aggravated spikelets degeneration, and low temperature stress made worse effect than high temperature stress. The rate of spikelet degeneration dramatically rose with the temperature falling below the critical temperature, the critical effective accumulated temperature, daily average temperature, daily maximum temperature and minimum temperature during panicle initiation were 550-600 ℃, 24.0-26.0 ℃, 32.0-34.0 ℃, 21.0-23.0 ℃, respectively. In practice, the natural condition of appropriate high temperature, large diurnal temperature gap and strong solar radiation were conducive to spikelet differentiation, and hindered the spikelet degeneration.

Room temperature solid-state quantum emitters in the telecom range.

PubMed

Zhou, Yu; Wang, Ziyu; Rasmita, Abdullah; Kim, Sejeong; Berhane, Amanuel; Bodrog, Zoltán; Adamo, Giorgio; Gali, Adam; Aharonovich, Igor; Gao, Wei-Bo

2018-03-01

On-demand, single-photon emitters (SPEs) play a key role across a broad range of quantum technologies. In quantum networks and quantum key distribution protocols, where photons are used as flying qubits, telecom wavelength operation is preferred because of the reduced fiber loss. However, despite the tremendous efforts to develop various triggered SPE platforms, a robust source of triggered SPEs operating at room temperature and the telecom wavelength is still missing. We report a triggered, optically stable, room temperature solid-state SPE operating at telecom wavelengths. The emitters exhibit high photon purity (~5% multiphoton events) and a record-high brightness of ~1.5 MHz. The emission is attributed to localized defects in a gallium nitride (GaN) crystal. The high-performance SPEs embedded in a technologically mature semiconductor are promising for on-chip quantum simulators and practical quantum communication technologies.

Rotating Cryocooler for Superconducting Motor

NASA Astrophysics Data System (ADS)

Ko, Junseok; Jeong, Sangkwon; Kim, Hongseong; Jung, Jeheon; Choi, Jaeyoung; In, Sehwan; Sohn, Myunghwan; Kwon, Young-Kil

2006-04-01

A single-stage coaxial pulse tube refrigerator has been designed for HTS (High Temperature Superconductor) motor application. This paper discusses a practical realization of an advanced cooling method for superconducting rotor, on-board cryocooler. When a cryocooler is considered to be mounted on the superconducting rotor, the following two factors must be satisfied for practical application. First, the on-board cryocooler should not disturb the high-speed revolution of the rotor. Second, at the same time, the high-speed revolution of the rotor should not deteriorate the cooling performance of the cryocooler. These mutual technical demands restrict the type of cryocooler suitable for high-speed rotating environment. We select a Stirling-type coaxial pulse tube cryocooler and incorporate it on the 1800-rpm superconducting motor mock-up. The pulse tube cryocooler is designed with an adiabatic model and a various loss mechanism analysis. The no-load temperature is approximately 100 K with less than 150 W electric input power. The axisymmetric configuration of the fabricated cryocooler does not produce any undesirable effect at high-speed rotation. Even if the thermal performance of the rotating pulse tube cryocooler is not satisfactory, the feasibility of simple on-board cooling method for superconducting rotor is confirmed in this paper.

High-speed measurement of an air transect's temperature shift heated by laser beam

NASA Astrophysics Data System (ADS)

Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

2005-02-01

Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

Durability of bends in high-temperature steam lines under the conditions of long-term operation

NASA Astrophysics Data System (ADS)

Katanakha, N. A.; Semenov, A. S.; Getsov, L. B.

2015-04-01

The article presents the results of stress-strain state computations and durability of bent and steeply curved branches of high-temperature steam lines carried out on the basis of the finite element method using the modified Soderberg formula for describing unsteady creep processes with taking the accumulation of damage into account. The computations were carried out for bends made of steel grades that are most widely used for manufacturing steam lines (12Kh1MF, 15Kh1M1F, and 10Kh9MFB) and operating at different levels of inner pressure and temperature. The solutions obtained using the developed creep model are compared with those obtained using the models widely used in practice.

Heat Stress and Injury Prevention Practices During Summer High School Football Training in South Texas.

PubMed

Hearon, Christopher M; Ruiz, Alberto; Taylor, Zachary J

The purpose was to describe practice conditions influencing the risk of heat stress to athletes in summer football training in South Texas high schools, and to compare these conditions to ACSM recommendations for heat stress/injury risk reduction in this population. Thirty ( N =30) high school summer football practices were observed. Wet bulb globe temperature (WBGT) was measured before/after practices and practices were observed for: duration/structure; athlete clothing; and rest break frequency/duration/content. Practices averaged 125±31 min and WBGT (pre- to post-practice) was 29.7±2.1°C to 31.2±2.2°C for morning, and 31.2±1.6°C to 28.9±1.2°C for evening practices. Most practices included contact (93%), and a majority were full-contact (53%). Most athletes wore full pads (83%) and medium/dark colored clothing (73%). Outside of scheduled breaks athletes removed helmets (63%), sat/knelt (63%), and had access to fluid (90%). Athletic trainers were present at 93% of the practices. A typical practice had 3 rest breaks, each lasting approximately 5 min. During breaks, athletes were provided fluid (93%), removed helmets (89%), and sat/knelt (76%), but were rarely provided shade (2%). While none of the practice sessions were conducted in conditions warranting the cancellation of outside activity (WBGT>33.1°C), the environmental data confirms that this region presents athletes with a very high risk of heat stress/injury. While a majority of the schools were taking many of the precautionary measures recommended by ACSM, many of the guidelines were not being followed. Governing bodies of high school athletics need to encourage compliance with recommendations for the reduction of heat stress/injury in this population.

Lead recovery from waste CRT funnel glass by high-temperature melting process.

PubMed

Hu, Biao; Hui, Wenlong

2018-02-05

In this research, a novel and effective process for waste CRT funnel glass treatment was developed. The key to this process is removal of lead from the CRT funnel glass by high-temperature melting process. Sodium carbonate powder was used as a fusion agent, sodium sulfide serves as a catalytic agent and carbon powder acts as reducing agent. Experimental results showed that lead recovery rate increased with an increase in the amount of added sodium carbonate, sodium sulfide, carbonate, temperature and holding time initially, and then reached a stable value. The maximum lead recovery rate was approximately 94%, when the optimum adding amount of sodium carbonate, sodium sulfide, carbonate, temperature and holding time were 25%, 8%, 3.6%, 1200°C and 120min, respectively. In the high-temperature melting process, lead silicate in the funnel glass was firstly reduced, and then removed. The glass slag can be made into sodium and potassium silicate by hydrolysis process. This study proposed a practical and economical process for recovery of lead and utilization of waste glass slag. Copyright © 2017 Elsevier B.V. All rights reserved.

Temperature Prediction in High Speed Bone Grinding using Motor PWM Signal

PubMed Central

Tai, Bruce L.; Zhang, Lihui; Wang, Anthony C.; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J.

2013-01-01

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. PMID:23806419

Experimental and numerical studies of burning velocities and kinetic modeling for practical and surrogate fuels

NASA Astrophysics Data System (ADS)

Zhao, Zhenwei

To help understand the fuel oxidation process in practical combustion environments, laminar flame speeds and high temperature chemical kinetic models were studied for several practical fuels and "surrogate" fuels, such as propane, dimethyl ether (DME), and primary reference fuel (PRF) mixtures, gasoline and n-decane. The PIV system developed for the present work is described. The general principles for PIV measurements are outlined and the specific considerations are also reported. Laminar flame speeds were determined for propane/air over a range of equivalence ratios at initial temperature of 298 K, 500 K and 650 K and atmospheric pressure. Several data sets for propane/air laminar flame speeds with N 2 dilution are also reported. These results are compared to the literature data collected at the same conditions. The propane flame speed is also numerically calculated with a detailed kinetic model and multi component diffusion, including Soret effects. This thesis also presents experimentally determined laminar flame speeds for primary reference fuel (PRF) mixtures of n-heptane/iso-octane and real gasoline fuel at different initial temperature and at atmospheric pressure. Nitrogen dilution effects on the laminar flame speed are also studied for selected equivalence ratios at the same conditions. A minimization of detailed kinetic model for PRF mixtures on laminar flame speed conditions was performed and the measured flame speeds were compared with numerical predictions using this model. The measured laminar flame speeds of n-decane/air mixtures at 500 K and at atmospheric pressure with and without dilution were determined. The measured flame speeds are significantly different that those predicted using existing published kinetic models, including a model validated previously against high temperature data from flow reactor, jet-stirred reactor, shock tube ignition delay, and burner stabilized flame experiments. A significant update of this model is described which continues to predict the earlier validation experiments as well as the newly acquired laminar flame speed data and other recently published shock tube ignition delay measurements. A high temperature decomposition and oxidation model based on a hierarchical nature of reacting systems to reflect the new development in the small molecule and radical kinetics and thermochemistry and to evaluate recent measurements of DME laminar flame speeds is developed. The, thermal decomposition of DME was studied theoretically by using the RRKM/master equation approach and the high temperature model was then compared with the literature experimental data. The new model predicts well high temperature flow reactor data, high temperature shock tube ignition delays, and the species profiles from the burner-stabilized flames. Predictions of laminar flame speed and jet-stirred reactor data also reasonably agree with the available experimental data. The remaining uncertainties that need to be addressed for further model improvement will also be discussed. This thesis also presents a novel temperature-dependent feature sensitivity analysis methodology for combustion modeling. The obtained information is demonstrated to be of critical relevance in optimizing complex reaction schemes against multiple experimental targets. Applications of the presented approach are not limited to sensitivities with respect to reaction rate coefficients; the method can also be used to investigate any temperature-dependent property of interest (such as binary diffusion coefficients). This application is also demonstrated in this thesis.

Strong, ductile, and thermally stable Cu-based metal-intermetallic nanostructured composites.

PubMed

Dusoe, Keith J; Vijayan, Sriram; Bissell, Thomas R; Chen, Jie; Morley, Jack E; Valencia, Leopolodo; Dongare, Avinash M; Aindow, Mark; Lee, Seok-Woo

2017-01-09

Bulk metallic glasses (BMGs) and nanocrystalline metals (NMs) have been extensively investigated due to their superior strengths and elastic limits. Despite these excellent mechanical properties, low ductility at room temperature and poor microstructural stability at elevated temperatures often limit their practical applications. Thus, there is a need for a metallic material system that can overcome these performance limits of BMGs and NMs. Here, we present novel Cu-based metal-intermetallic nanostructured composites (MINCs), which exhibit high ultimate compressive strengths (over 2 GPa), high compressive failure strain (over 20%), and superior microstructural stability even at temperatures above the glass transition temperature of Cu-based BMGs. Rapid solidification produces a unique ultra-fine microstructure that contains a large volume fraction of Cu 5 Zr superlattice intermetallic compound; this contributes to the high strength and superior thermal stability. Mechanical and microstructural characterizations reveal that substantial accumulation of phase boundary sliding at metal/intermetallic interfaces accounts for the extensive ductility observed.

Development of Rail Temperature Prediction Model : Research Results

DOT National Transportation Integrated Search

2008-06-01

Preventing track buckling is important to the railroad industry's goal of operational safety. It is a common practice for railroads to impose slow orders during hot weather when the risk of track buckling is high. Numerous factors affect track buckli...

High Energy Density and High Temperature Multilayer Capacitor Films for Electric Vehicle Applications

NASA Astrophysics Data System (ADS)

Treufeld, Imre; Song, Michelle; Zhu, Lei; Baer, Eric; Snyder, Joe; Langhe, Deepak

2015-03-01

Multilayer films (MLFs) with high energy density and high temperature capability (>120 °C) have been developed at Case Western Reserve University. Such films offer a potential solution for electric car DC-link capacitors, where high ripple currents and high temperature tolerance are required. The current state-of-the-art capacitors used in electric cars for converting DC to AC use biaxially oriented polypropylene (BOPP), which can only operate at temperatures up to 85 °C requiring an external cooling system. The polycarbonate (PC)/poly(vinylidene fluoride) (PVDF) MLFs have a higher permittivity compared to that of BOPP (2.3), leading to higher energy density. They have good mechanical stability and reasonably low dielectric losses at 120 °C. Nonetheless, our preliminary dielectric measurements show that the MLFs exhibit appreciable dielectric losses (20%) at 120 °C, which would, despite all the other advantages, make them not suitable for practical applications. Our preliminary data showed that dielectric losses of the MLFs at 120 °C up to 400 MV/m and 1000 Hz originate mostly from impurity ionic conduction. This work is supported by the NSF PFI/BIC Program (IIP-1237708).

Replication fidelity improvement of PMMA microlens array based on weight evaluation and optimization

NASA Astrophysics Data System (ADS)

Jiang, Bing-yan; Shen, Long-jiang; Peng, Hua-jiang; Yin, Xiang-lin

2007-12-01

High replication fidelity is a prerequisite of high quality plastic microlens array in injection molding. But, there's not an economical and practical method to evaluate and improve the replication fidelity until now. Based on part weight evaluation and optimization, this paper presents a new method of replication fidelity improvement. Firstly, a simplified analysis model of PMMA micro columns arrays (5×16) with 200μm diameter was set up. And then, Flow (3D) module of Moldflow MPI6.0 based on Navier-Stokes equations was used to calculate the weight of the micro columns arrays in injection molding. The effects of processing parameters (melt temperature, mold temperature, injection time, packing pressure and packing time) on the part weight were investigated in the simulations. The simulation results showed that the mold temperature and the injection time have important effects on the filling of micro columns; the optimal mold temperature and injection time for better replication fidelity could be determined by the curves of mold temperature vs part weight and injection time vs part weight. At last, the effects of processing parameters on part weight of micro columns array were studied experimentally. The experimental results showed that the increase of melt temperature and mold temperature can make the packing pressure transfer to micro cavity more effectively through runner system, and increase the part weight. From the observation results of the image measuring apparatus, it was discovered that the higher the part weight, the better the filling of the microstructures. In conclusion, part weight can be used to evaluate the replication fidelity of micro-feature structured parts primarily; which is an economical and practical method to improve the replication fidelity of microlens arrays based on weight evaluation and optimization.

High-Tc superconductor coplanar waveguide filter

NASA Technical Reports Server (NTRS)

Chew, Wilbert; Bajuk, Louis J.; Cooley, Thomas W.; Foote, Marc C.; Hunt, Brian D.; Rascoe, Daniel L.; Riley, A. L.

1991-01-01

Coplanar waveguide (CPW) low-pass filters made of YBa2Cu3O(7-delta) (YBCO) on LaAlO3 substrates, with dimensions suited for integrated circuits, were fabricated and packaged. A complete filter gives a true idea of the advantages and difficulties in replacing thin-film metal with a high-temperature superconductor in a practical circuit. Measured insertion losses in liquid nitrogen were superior to the loss of a similar thin-film copper filter throughout the 0- to 9.5-GHz passband. These results demonstrate the performance of fully patterned YBCO in a practical CPW structure after sealing in a hermetic package.

Ultralight, Recoverable, and High-Temperature-Resistant SiC Nanowire Aerogel.

PubMed

Su, Lei; Wang, Hongjie; Niu, Min; Fan, Xingyu; Ma, Mingbo; Shi, Zhongqi; Guo, Sheng-Wu

2018-04-24

Ultralight ceramic aerogels with the property combination of recoverable compressibility and excellent high-temperature stability are attractive for use in harsh environments. However, conventional ceramic aerogels are usually constructed by oxide ceramic nanoparticles, and their practical applications have always been limited by the brittle nature of ceramics and volume shrinkage at high temperature. Silicon carbide (SiC) nanowire offers the integrated properties of elasticity and flexibility of one-dimensional (1D) nanomaterials and superior high-temperature thermal and chemical stability of SiC ceramics, which makes it a promising building block for compressible ceramic nanowire aerogels (NWAs). Here, we report the fabrication and properties of a highly porous three-dimensional (3D) SiC NWA assembled by a large number of interweaving 3C-SiC nanowires of 20-50 nm diameter and tens to hundreds of micrometers in length. The SiC NWA possesses ultralow density (∼5 mg cm -3 ), excellent mechanical properties of large recoverable compression strain (>70%) and fatigue resistance, refractory property, oxidation and high-temperature resistance, and thermal insulating property (0.026 W m -1 K -1 at room temperature in N 2 ). When used as absorbents, the SiC NWAs exhibit an adsorption selectivity of low-viscosity organic solvents with high absorption capacity (130-237 g g -1 ). The successful fabrication of such an attractive material may provide promising perspectives to the design and fabrication of other compressible and multifunctional ceramic NWAs.

Absorption of solar radiation by alkali vapors. [for efficient high temperature energy converters

NASA Technical Reports Server (NTRS)

Mattick, A. T.

1978-01-01

A theoretical study of the direct absorption of solar radiation by the working fluid of high temperature, high efficiency energy converters has been carried out. Alkali vapors and potassium vapor in particular were found to be very effective solar absorbers and suitable thermodynamically for practical high temperature cycles. Energy loss via reradiation from a solar boiler was shown to reduce the overall efficiency of radiation-heated energy converters, although a simple model of radiation transfer in a potassium vapor solar boiler revealed that self-trapping of the reradiation may reduce this loss considerably. A study was also made of the requirements for a radiation boiler window. It was found that for sapphire, one of the best solar transmitting materials, the severe environment in conjunction with high radiation densities will require some form of window protection. An aerodynamic shield is particularly advantageous in this capacity, separating the window from the absorbing vapor to prevent condensation and window corrosion and to reduce the radiation density at the window.

Evaporation of oil-water emulsion drops when heated at high temperature

NASA Astrophysics Data System (ADS)

Strizhak, P. A.; Piskunov, M. V.; Kuznetsov, G. V.; Voytkov, I. S.

2017-10-01

An experimental study on conditions and main characteristics for high-temperature (more than 700 K) evaporation of oil-water drops is presented. The high-temperature water purification from impurities can be the main practical application of research results. Thus, the heating of drops is implemented by the two typical schemes: on a massive substrate (the heating conditions are similar to those achieved in a heating chamber) and in a flow of the heated air. In the latter case, the heating conditions correspond to those attained while moving water drops with impurities in a counter high-temperature gaseous flow in the process of water purification. Evaporation time as function of heating temperature is presented. The influence of oil product concentration in an emulsion drop on evaporation characteristics is discussed. The conditions for intensive flash boiling of an emulsion drop and its explosive breakup with formation of the fine droplets cloud are pointed out. Heat fluxes required for intensive flash boiling and explosive breakup of a drop with further formation of the fine aerosol are determined in the boundary layer of a drop. The fundamental differences between flash boiling and explosive breakup of an emulsion drop when heated on a substrate and in a flow of the heated air are described. The main prospects for the development of the high-temperature water purification technology are detailed taking into account the fast emulsion drop breakup investigated in the paper.

High Incubation Temperature and Threonine Dietary Level Improve Ileum Response Against Post-Hatch Salmonella Enteritidis Inoculation in Broiler Chicks

PubMed Central

de Oliveira, Heraldo Bezerra; Campos, Danila Barreiro; Guerra, Ricardo Romão; Costa, Fernando Guilherme Perazzo

2015-01-01

This study assessed the effect of both embryonic thermal manipulation and dietary threonine level on the response of broilers inoculated with Salmonella Enteritidis, considering bacterial counts in the cecal contents, intestinal morphology, mucin and heat shock protein 70 gene expression, body weight and weight gain. Thermal manipulation was used from 11 days of incubation until hatch, defining three treatments: standard (37.7°C), continuous high temperature (38.7°C) and continuous low temperature (36.7°C). After hatch, chicks were distributed according to a 3x2+1 factorial arrangement (three temperatures and two threonine levels and one sham-inoculated control). At two days of age, all chicks were inoculated with Salmonella Enteritidis, except for the sham-inoculated control group. There was no interaction between the factors on any analyses. High temperature during incubation was able to reduce colonization by Salmonella Enteritidis in the first days, reducing both Salmonella counts and the number of positive birds. It also increased mucin expression and decreased Hsp70 expression compared with other inoculated groups. High temperature during incubation and high threonine level act independently to reduce the negative effects associated to Salmonella Enteritidis infection on intestinal morphology and performance, with results similar to sham-inoculated birds. The findings open new perspectives for practical strategies towards the pre-harvest Salmonella control in the poultry industry. PMID:26131553

Stable operation of a Secure QKD system in the real-world setting

NASA Astrophysics Data System (ADS)

Tomita, Akihisa

2007-06-01

Quantum Key Distribution (QKD) now steps forward from the proof of principle to the validation of the practical feasibility. Nevertheless, the QKD technology should respond to the challenges from the real-world such as stable operation against the fluctuating environment, and security proof under the practical setting. We report our recent progress on stable operation of a QKD system, and key generation with security assurance. A QKD system should robust to temperature fluctuation in a common office environment. We developed a loop-mirror, a substitution of a Faraday mirror, to allow easy compensation for the temperature dependence of the device. Phase locking technique was also employed to synchronize the system clock to the quantum signals. This technique is indispensable for the transmission system based on the installed fiber cables, which stretch and shrink due to the temperature change. The security proof of QKD, however, has assumed the ideal conditions, such as the use of a genuine single photon source and/or unlimited computational resources. It has been highly desirable to give an assurance of security for practical systems, where the ideal conditions are no longer satisfied. We have constructed a theory to estimate the leakage information on the transmitted key under the practically attainable conditions, and have developed a QKD system equipped with software for secure key distillation. The QKD system generates the final key at the rate of 2000 bps after 20 km fiber transmission. Eavesdropper's information on the final key is guaranteed to be less than 2-7 per bit. This is the first successful generation of the secure key with quantitative assurance of the upper bound of the leakage information. It will put forth the realization of highly secure metropolitan optical communication network against any types of eavesdropping.

Application of time-division-multiplexed lasers for measurements of gas temperature and CH4 and H2O concentrations at 30 kHz in a high-pressure combustor.

PubMed

Caswell, Andrew W; Kraetschmer, Thilo; Rein, Keith; Sanders, Scott T; Roy, Sukesh; Shouse, Dale T; Gord, James R

2010-09-10

Two time-division-multiplexed (TDM) sources based on fiber Bragg gratings were applied to monitor gas temperature, H(2)O mole fraction, and CH(4) mole fraction using line-of-sight absorption spectroscopy in a practical high-pressure gas turbine combustor test article. Collectively, the two sources cycle through 14 wavelengths in the 1329-1667 nm range every 33 μs. Although it is based on absorption spectroscopy, this sensing technology is fundamentally different from typical diode-laser-based absorption sensors and has many advantages. Specifically, the TDM lasers allow efficient, flexible acquisition of discrete-wavelength information over a wide spectral range at very high speeds (typically 30 kHz) and thereby provide a multiplicity of precise data at high speeds. For the present gas turbine application, the TDM source wavelengths were chosen using simulated temperature-difference spectra. This approach is used to select TDM wavelengths that are near the optimum values for precise temperature and species-concentration measurements. The application of TDM lasers for other measurements in high-pressure, turbulent reacting flows and for two-dimensional tomographic reconstruction of the temperature and species-concentration fields is also forecast.

Good vaccination practice: it all starts with a good vaccine storage temperature.

PubMed

Vangroenweghe, Frédéric

2017-01-01

Recent introduction of strategies to reduce antibiotic use in food animal production implies an increased use of vaccines in order to prevent the economic impact of several important diseases in swine. Good Vaccination Practice (GVP) is an overall approach on the swine farm aiming to obtain maximal efficacy of vaccination through good storage, preparation and finally correct application to the target animals. In order to have a better insight into GVP on swine farms and the vaccine storage conditions, a survey on vaccination practices was performed on a farmers' fair and temperatures in the vaccine storage refrigerators were measured during farm visits over a period of 1 year. The survey revealed that knowledge on GVP, such as vaccine storage and handling, needle management and injection location could be improved. Less than 10% had a thermometer in their vaccine storage refrigerator on the moment of the visit. Temperature measurement revealed that only 71% of the measured refrigerators were in line with the recommended temperature range of +2 °C to +8 °C. Both below +2 °C and above +8 °C temperatures were registered during all seasons of the year. Compliance was lower during summer with an average temperature of 9.2 °C while only 43% of the measured temperatures were within the recommended range. The present study clearly showed the need for continuous education on GVP for swine veterinarians, swine farmers and their farm personnel in general and vaccine storage management in particular. In veterinary medicine, the correct storage of vaccines is crucial since both too low and too high temperatures can provoke damage to specific vaccine types. Adjuvanted killed or subunit vaccines can be damaged (e.g. structure of aluminiumhydroxide in adjuvans) by too low temperatures (below 0 °C), whereas lyophilized live vaccines are susceptible (e.g. loss of vaccine potency) to heat damage by temperatures above +8 °C. In conclusion, knowledge and awareness of GVP and vaccine storage conditions are crucial under practical field conditions in swine herds. Focus on a correct on-farm vaccine storage is part of the responsible veterinarians' guidance in order to obtain the required vaccine efficacy.

One-Way Temperature Compensated Fiber Link

DTIC Science & Technology

2011-05-01

frequency is through two way satellite time and frequency transfer ( TWSTFT ). While it is practical for transmitting time and frequency over long distance...the performance is not acceptable for some of the newer high quality clocks. Currently, TWSTFT can transmit frequencies with instabilities at the

Radiation intensification of the reactor pressure vessels recovery by low temperature heat treatment (wet annealing)

NASA Astrophysics Data System (ADS)

Krasikov, E.

2015-04-01

As a main barrier against radioactivity outlet reactor pressure vessel (RPV) is a key component in terms of NPP safety. Therefore present-day demands in RPV reliability enhance have to be met by all possible actions for RPV in-service embrittlement mitigation. Annealing treatment is known to be the effective measure to restore the RPV metal properties deteriorated by neutron irradiation. There are two approaches to annealing. The first one is so-called «dry» high temperature (∼475°C) annealing. It allows obtaining practically complete recovery, but requires the removal of the reactor core and internals. External heat source (furnace) is required to carry out RPV heat treatment. The alternative approach is to anneal RPV at a maximum coolant temperature which can be obtained using the reactor core or primary circuit pumps while operating within the RPV design limits. This low temperature «wet» annealing, although it cannot be expected to produce complete recovery, is more attractive from the practical point of view especially in cases when the removal of the internals is impossible.

Microsoft excel spreadsheets for calculation of P-V-T relations and thermodynamic properties from equations of state of MgO, diamond and nine metals as pressure markers in high-pressure and high-temperature experiments

NASA Astrophysics Data System (ADS)

Sokolova, Tatiana S.; Dorogokupets, Peter I.; Dymshits, Anna M.; Danilov, Boris S.; Litasov, Konstantin D.

2016-09-01

We present Microsoft Excel spreadsheets for calculation of thermodynamic functions and P-V-T properties of MgO, diamond and 9 metals, Al, Cu, Ag, Au, Pt, Nb, Ta, Mo, and W, depending on temperature and volume or temperature and pressure. The spreadsheets include the most common pressure markers used in in situ experiments with diamond anvil cell and multianvil techniques. The calculations are based on the equation of state formalism via the Helmholtz free energy. The program was developed using Visual Basic for Applications in Microsoft Excel and is a time-efficient tool to evaluate volume, pressure and other thermodynamic functions using T-P and T-V data only as input parameters. This application is aimed to solve practical issues of high pressure experiments in geosciences and mineral physics.

Self-validating type C thermocouples to 2300 °C using high temperature fixed points

NASA Astrophysics Data System (ADS)

Pearce, J. V.; Elliott, C. J.; Machin, G.; Ongrai, O.

2013-09-01

Above 1500 °C, tungsten-rhenium (W-Re) thermocouples are the most commonly used contact thermometers because they are practical and inexpensive. However in general loss of calibration is very rapid, and, due to their embrittlement at high temperature, it is generally not possible to remove them for recalibration from the process environments in which they are used. Even if removal for recalibration was possible this would be of, at best, very limited use due to large inhomogeneity effects. Ideally, these thermocouples require some mechanism to monitor their drift in-situ. In this study, we describe self-validation of Type C (W5%Re/W26%Re) thermocouples by means of miniature high temperature fixed points comprising crucibles containing respectively Co-C, Pt-C, Ru-C, and Ir-C eutectic alloys. An overview of developments in this area is presented.

An arc tangent function demodulation method of fiber-optic Fabry-Perot high-temperature pressure sensor

NASA Astrophysics Data System (ADS)

Ren, Qianyu; Li, Junhong; Hong, Yingping; Jia, Pinggang; Xiong, Jijun

2017-09-01

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier (PGC) is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array (FPGA) to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results: 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.

Room temperature solid-state quantum emitters in the telecom range

PubMed Central

Bodrog, Zoltán; Adamo, Giorgio; Gali, Adam

2018-01-01

On-demand, single-photon emitters (SPEs) play a key role across a broad range of quantum technologies. In quantum networks and quantum key distribution protocols, where photons are used as flying qubits, telecom wavelength operation is preferred because of the reduced fiber loss. However, despite the tremendous efforts to develop various triggered SPE platforms, a robust source of triggered SPEs operating at room temperature and the telecom wavelength is still missing. We report a triggered, optically stable, room temperature solid-state SPE operating at telecom wavelengths. The emitters exhibit high photon purity (~5% multiphoton events) and a record-high brightness of ~1.5 MHz. The emission is attributed to localized defects in a gallium nitride (GaN) crystal. The high-performance SPEs embedded in a technologically mature semiconductor are promising for on-chip quantum simulators and practical quantum communication technologies. PMID:29670945

Regeneration of glass nanofluidic chips through a multiple-step sequential thermochemical decomposition process at high temperatures.

PubMed

Xu, Yan; Wu, Qian; Shimatani, Yuji; Yamaguchi, Koji

2015-10-07

Due to the lack of regeneration methods, the reusability of nanofluidic chips is a significant technical challenge impeding the efficient and economic promotion of both fundamental research and practical applications on nanofluidics. Herein, a simple method for the total regeneration of glass nanofluidic chips was described. The method consists of sequential thermal treatment with six well-designed steps, which correspond to four sequential thermal and thermochemical decomposition processes, namely, dehydration, high-temperature redox chemical reaction, high-temperature gasification, and cooling. The method enabled the total regeneration of typical 'dead' glass nanofluidic chips by eliminating physically clogged nanoparticles in the nanochannels, removing chemically reacted organic matter on the glass surface and regenerating permanent functional surfaces of dissimilar materials localized in the nanochannels. The method provides a technical solution to significantly improve the reusability of glass nanofluidic chips and will be useful for the promotion and acceleration of research and applications on nanofluidics.

Accelerated life testing effects on CMOS microcircuit characteristics

NASA Technical Reports Server (NTRS)

1980-01-01

The 250 C, 200C and 125C accelerated tests are described. The wear-out distributions from the 250 and 200 C tests were used to estimate the activation energy between the two test temperatures. The duration of the 125 C test was not sufficient to bring the test devices into the wear-out region. It was estimated that, for the most complex of the three devices types, the activation energy between 200 C and 125 C should be at least as high as that between 250 C and 200 C. The practicality of the use of high temperature for the accelerated life tests from the point of view of durability of equipment is assessed. Guidlines for the development of accelerated life-test conditions are proposed. The use of the silicon nitride overcoat to improve the high temperature accelerated life-test characteristics of CMOS microcircuits is described.

Development of ultra-high temperature material characterization capabilities using digital image correlation analysis

NASA Astrophysics Data System (ADS)

Cline, Julia Elaine

2011-12-01

Ultra-high temperature deformation measurements are required to characterize the thermo-mechanical response of material systems for thermal protection systems for aerospace applications. The use of conventional surface-contacting strain measurement techniques is not practical in elevated temperature conditions. Technological advancements in digital imaging provide impetus to measure full-field displacement and determine strain fields with sub-pixel accuracy by image processing. In this work, an Instron electromechanical axial testing machine with a custom-designed high temperature gripping mechanism is used to apply quasi-static tensile loads to graphite specimens heated to 2000°F (1093°C). Specimen heating via Joule effect is achieved and maintained with a custom-designed temperature control system. Images are captured at monotonically increasing load levels throughout the test duration using an 18 megapixel Canon EOS Rebel T2i digital camera with a modified Schneider Kreutznach telecentric lens and a combination of blue light illumination and narrow band-pass filter system. Images are processed using an open-source Matlab-based digital image correlation (DIC) code. Validation of source code is performed using Mathematica generated images with specified known displacement fields in order to gain confidence in accurate software tracking capabilities. Room temperature results are compared with extensometer readings. Ultra-high temperature strain measurements for graphite are obtained at low load levels, demonstrating the potential for non-contacting digital image correlation techniques to accurately determine full-field strain measurements at ultra-high temperature. Recommendations are given to improve the experimental set-up to achieve displacement field measurements accurate to 1/10 pixel and strain field accuracy of less than 2%.

Influence of Agricultural Practice on Surface Temperature

NASA Astrophysics Data System (ADS)

Czajkowski, K.; Ault, T.; Hayase, R.; Benko, T.

2006-12-01

Changes in land uses/covers can have a significant effect on the temperature of the Earth's surface. Agricultural fields exhibit a significant change in land cover within a single year and from year to year as different crops are planted. These changes in agricultural practices including tillage practice and crop type influence the energy budget as reflected in differences in surface temperature. In this project, Landsat 5 and 7 imagery were used to investigate the influence of crop type and tillage practice on surface temperature in Iowa and NW Ohio. In particular, the three crop rotation of corn, soybeans and wheat, as well as no-till, conservation tillage and tradition tillage methods, were investigated. Crop type and conservation tillage practices were identified using supervised classification. Student surface temperature observations from the GLOBE program were used to correct for the effects of the atmosphere for some of the satellite thermal observations. Students took surface temperature observations in field sites near there schools using hand- held infrared thermometers.

Low Temperature Reactivities of Ultra-High Temperature Ceramics (Hf-X System)

DTIC Science & Technology

2006-03-01

as interacting fillers with the preceramic polymer formulations. In situ formation of the SiC phase was also evaluated as a practical approach in...silicon (reaction-bonded SiC ), which was introduced either as a powder mixed in the original composite formulation or as a subsequent infiltrant that...and their aerospace and turbine applications has led to a renewal of activities to fabricate MB 2/ SiC composites as the materials of choice, because

Microbial desulfurization of coal

NASA Technical Reports Server (NTRS)

Dastoor, M. N.; Kalvinskas, J. J.

1978-01-01

Experiments indicate that several sulfur-oxidizing bacteria strains have been very efficient in desulfurizing coal. Process occurs at room temperature and does not require large capital investments of high energy inputs. Process may expand use of abundant reserves of high-sulfur bituminous coal, which is currently restricted due to environmental pollution. On practical scale, process may be integrated with modern coal-slurry transportation lines.

High thermal stability and sluggish crystallization kinetics of high-entropy bulk metallic glasses

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

Yang, M.; Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon; Liu, X. J.

2016-06-28

Metallic glasses are metastable and their thermal stability is critical for practical applications, particularly at elevated temperatures. The conventional bulk metallic glasses (BMGs), though exhibiting high glass-forming ability (GFA), crystallize quickly when being heated to a temperature higher than their glass transition temperature. This problem may potentially be alleviated due to the recent developments of high-entropy (or multi-principle-element) bulk metallic glasses (HE-BMGs). In this work, we demonstrate that typical HE-BMGs, i.e., ZrTiHfCuNiBe and ZrTiCuNiBe, have higher kinetic stability, as compared with the benchmark glass Vitreoy1 (Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5}) with a similar chemical composition. The measured activation energymore » for glass transition and crystallization of the HE-BMGs is nearly twice that of Vitreloy 1. Moreover, the sluggish crystallization region ΔT{sub pl-pf}, defined as the temperature span between the last exothermic crystallization peak temperature T{sub pl} and the first crystallization exothermic peak temperature T{sub pf}, of all the HE-BMGs is much wider than that of Vitreloy 1. In addition, high-resolution transmission electron microscopy characterization of the crystallized products at different temperatures and the continuous heating transformation diagram which is proposed to estimate the lifetime at any temperature below the melting point further confirm high thermal stability of the HE-BMGs. Surprisingly, all the HE-BMGs show a small fragility value, which contradicts with their low GFA, suggesting that the underlying diffusion mechanism in the liquid and the solid of HE-BMGs is different.« less

Effects of water turbidity and different temperatures on oxidative stress in caddisfly (Stenopsyche marmorata) larvae.

PubMed

Suzuki, Jumpei; Imamura, Masahiro; Nakano, Daisuke; Yamamoto, Ryosuke; Fujita, Masafumi

2018-07-15

Anthropogenic water turbidity derived from suspended solids (SS) is caused by reservoir sediment management practices such as drawdown flushing. Turbid water induces stress in many aquatic organisms, but the effects of turbidity on oxidative stress responses in aquatic insects have not yet been demonstrated. Here, we examined antioxidant responses, oxidative damage, and energy reserves in caddisfly (Stenopsyche marmorata) larvae exposed to turbid water (0 mg SS L -1 , 500 mg SS L -1 , and 2000 mg SS L -1 ) at different temperatures. We evaluated the combined effects of turbid water and temperature by measuring oxidative stress and using metabolic biomarkers. No turbidity level was significantly lethal to S. marmorata larvae. Moreover, there were no significant differences in antioxidant response or oxidative damage between the control and turbid water treatments at a low temperature (10 °C). However, at a high temperature (25 °C), turbid water modulated the activity of the antioxidant enzymes superoxide dismutase and catalase and the oxygen radical absorbance capacity as an indicator of the redox state of the insect larvae. Antioxidant defenses require energy, and high temperature was associated with low energy reserves, which might limit the capability of organisms to counteract reactive oxygen species. Moreover, co-exposure to turbid water and high temperature caused fluctuation of antioxidant defenses and increased the oxidative damage caused by the production of reactive oxygen species. Furthermore, the combined effect of high temperature and turbid water on antioxidant defenses and oxidative damage was larger than the individual effects. Therefore, our results demonstrate that exposure to both turbid water and high temperature generates additive and synergistic interactions causing oxidative stress in this aquatic insect species. Copyright © 2018. Published by Elsevier B.V.

Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis.

PubMed

Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

2015-02-26

This study developed a facile approach for preparing Ti(3+) self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti(3+) doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti(3+) in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications.

Facile synthesis of the Ti3+ self-doped TiO2-graphene nanosheet composites with enhanced photocatalysis

NASA Astrophysics Data System (ADS)

Qiu, Bocheng; Zhou, Yi; Ma, Yunfei; Yang, Xiaolong; Sheng, Weiqin; Xing, Mingyang; Zhang, Jinlong

2015-02-01

This study developed a facile approach for preparing Ti3+ self-doped TiO2-graphene photocatalyst by a one-step vacuum activation technology involved a relative lower temperature, which could be activated by the visible light owing to the synergistic effect among Ti3+ doping, some new intersurface bonds generation and graphene oxide reduction. Compared with the traditional methods, the vacuum activation involves a low temperature and low-costing, which can achieve the reduction of GO, the self doping of Ti3+ in TiO2 and the loading of TiO2 nanoparticles on GR surface at the same time. These resulting TiO2-graphene composites show the high photodegradation rate of MO, high hydrogen evolution activity and excellent IPCE in the visible light irradiation. The facile vacuum activation method can provide an effective and practical approach to improve the performance of TiO2-graphene and other metal oxides-graphene towards their practical photocatalytic applications.

Maintaining high moisture content of macadamia nuts-in-shell during storage induces brown centres in raw kernels.

PubMed

Walton, David A; Randall, Bruce W; Le Lagadec, Marie D; Wallace, Helen M

2013-09-01

Kernel brown centres in macadamia are a defect causing internal discolouration of kernels. This study investigates the effect on the incidence of brown centres in raw kernel after maintaining high moisture content in macadamia nuts-in-shell stored at temperatures of 30°C, 35°C, 40°C and 45°C. Brown centres of raw kernel increased with nuts-in-shell storage time and temperature when high moisture content was maintained by sealing in polyethylene bags. Almost all kernels developed the defect when kept at high moisture content for 5 days at 45°C, and 44% developed brown centres after only 2 days of storage at high moisture content at 45°C. This contrasted with only 0.76% when stored for 2 days at 45°C but allowed to dry in open-mesh bags. At storage temperatures below 45°C, there were fewer brown centres, but there were still significant differences between those stored at high moisture content and those allowed to dry (P < 0.05). Maintenance of high moisture content during macadamia nuts-in-shell storage increases the incidence of brown centres in raw kernels and the defect increases with time and temperature. On-farm nuts-in-shell drying and storage practices should rapidly remove moisture to reduce losses. Ideally, nuts-in-shell should not be stored at high moisture content on-farm at temperatures over 30°C. © 2013 Society of Chemical Industry.

A retrospective analysis of American football hyperthermia deaths in the United States

NASA Astrophysics Data System (ADS)

Grundstein, Andrew J.; Ramseyer, Craig; Zhao, Fang; Pesses, Jordan L.; Akers, Pete; Qureshi, Aneela; Becker, Laura; Knox, John A.; Petro, Myron

2012-01-01

Over the period 1980-2009, there were 58 documented hyperthermia deaths of American-style football players in the United States. This study examines the geography, timing, and meteorological conditions present during the onset of hyperthermia, using the most complete dataset available. Deaths are concentrated in the eastern quadrant of the United States and are most common during August. Over half the deaths occurred during morning practices when high humidity levels were common. The athletes were typically large (79% with a body mass index >30) and mostly (86%) played linemen positions. Meteorological conditions were atypically hot and humid by local standards on most days with fatalities. Further, all deaths occurred under conditions defined as high or extreme by the American College of Sports Medicine using the wet bulb globe temperature (WBGT), but under lower threat levels using the heat index (HI). Football-specific thresholds based on clothing (full football uniform, practice uniform, or shorts) were also examined. The thresholds matched well with data from athletes wearing practice uniforms but poorly for those in shorts only. Too few cases of athletes in full pads were available to draw any broad conclusions. We recommend that coaches carefully monitor players, particularly large linemen, early in the pre-season on days with wet bulb globe temperatures that are categorized as high or extreme. Also, as most of the deaths were among young athletes, longer acclimatization periods may be needed.

Treatment of Irradiated Graphite from French Bugey Reactor - 13424

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

Brown, Thomas; Poncet, Bernard

2013-07-01

Beginning in 2009, in order to determine an alternative to direct disposal for decommissioned irradiated graphite from EDF's Bugey NPP, Studsvik and EDF began a test program to determine if graphite decontamination and destruction were practicable using Studsvik's thermal organic reduction (THOR) technology. The testing program focused primarily on the release of C-14, H-3, and Cl-36 and also monitored graphite mass loss. For said testing, a bench-scale steam reformer (BSSR) was constructed with the capability of flowing various compositions of gases at temperatures up to 1300 deg. C over uniformly sized particles of graphite for fixed amounts of time. Themore » BSSR was followed by a condenser, thermal oxidizer, and NaOH bubbler system designed to capture H-3 and C-14. Also, in a separate series of testing, high concentration acid and peroxide solutions were used to soak the graphite and leach out and measure Cl-36. A series of gasification tests were performed to scope gas compositions and temperatures for graphite gasification using steam and oxygen. Results suggested higher temperature steam (1100 deg. C vs. 900 deg. C) yielded a practicable gasification rate but that lower temperature (900 deg. C) gasification was also a practicable treatment alternative if oxygen is fed into the process. A series of decontamination tests were performed to determine the release behavior of and extent to which C-14 and H-3 were released from graphite in a high temperature (900-1300 deg. C), low flow roasting gas environment. In general, testing determined that higher temperatures and longer roasting times were efficacious for releasing H-3 completely and the majority (80%) of C-14. Manipulating oxidizing and reducing gas environments was also found to limit graphite mass loss. A series of soaking tests was performed to measure the amount of Cl-36 in the samples of graphite before and after roasting in the BSSR. Similar to C-14 release, these soaking tests revealed that 70-80% Cl-36 is released during roasting tests. (authors)« less

Thermoelectric refrigeration for temperatures below 100 K: A study of titanium sesquioxide

NASA Technical Reports Server (NTRS)

Redebaugh, R.; Linenberger, D.; Spellicy, E.

1982-01-01

Previous measurements of the specific heat of V-doped Ti2O3 at low temperatures were explained by a model which also suggested the material would have a high thermoelectric figure-of-merit. The sample preparation, experimental apparatus, and the results of measurements on the thermal conductivity, thermoelectric power, and electrical resistivity of a single crystal Ti2O3 - 4% V sample are described. The results are used to derive the thermoelectric figure-of-merit between 5 and 300 K. The figure-of-merit is much smaller than expected and of little practical value because of the very high phonon thermal conductivity.

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

Driscoll, S.B.; Walton, T.C.

Polyimides have gained wide acceptance for use in many aerospace composite, electrical, and industrial applications. The intent of this work is to share with the reader practical knowledge of how some of the currently available commercial systems perform. Several prepreg processable polyimide systems were evaluated for adhesive properties and characterized with the use of SEM, TGA, DSC, TMA, Dynamic Spectroscopy, and Force vs. Time Electronic Impact Analyses for comparison. The chemistry and nature of these resin systems is reviewed, including several BMIs (new hot melts examined)., Amide-Imides (Al) and Thermoplastic Polyimide (TPI). PMR-15 and a high temperature epoxy resin aremore » included for comparison of high temperature properties. 17 references.« less

Ad hoc instrumentation methods in ecological studies produce highly biased temperature measurements

USGS Publications Warehouse

Terando, Adam J.; Youngsteadt, Elsa; Meineke, Emily K.; Prado, Sara G.

2017-01-01

In light of global climate change, ecological studies increasingly address effects of temperature on organisms and ecosystems. To measure air temperature at biologically relevant scales in the field, ecologists often use small, portable temperature sensors. Sensors must be shielded from solar radiation to provide accurate temperature measurements, but our review of 18 years of ecological literature indicates that shielding practices vary across studies (when reported at all), and that ecologists often invent and construct ad hoc radiation shields without testing their efficacy. We performed two field experiments to examine the accuracy of temperature observations from three commonly used portable data loggers (HOBO Pro, HOBO Pendant, and iButton hygrochron) housed in manufactured Gill shields or ad hoc, custom‐fabricated shields constructed from everyday materials such as plastic cups. We installed this sensor array (five replicates of 11 sensor‐shield combinations) at weather stations located in open and forested sites. HOBO Pro sensors with Gill shields were the most accurate devices, with a mean absolute error of 0.2°C relative to weather stations at each site. Error in ad hoc shield treatments ranged from 0.8 to 3.0°C, with the largest errors at the open site. We then deployed one replicate of each sensor‐shield combination at five sites that varied in the amount of urban impervious surface cover, which presents a further shielding challenge. Bias in sensors paired with ad hoc shields increased by up to 0.7°C for every 10% increase in impervious surface. Our results indicate that, due to variable shielding practices, the ecological literature likely includes highly biased temperature data that cannot be compared directly across studies. If left unaddressed, these errors will hinder efforts to predict biological responses to climate change. We call for greater standardization in how temperature data are recorded in the field, handled in analyses, and reported in publications.

Vanadium Dioxide Nanoparticle-based Thermochromic Smart Coating: High Luminous Transmittance, Excellent Solar Regulation Efficiency, and Near Room Temperature Phase Transition.

PubMed

Zhu, Jingting; Zhou, Yijie; Wang, Bingbing; Zheng, Jianyun; Ji, Shidong; Yao, Heliang; Luo, Hongjie; Jin, Ping

2015-12-23

An annealing-assisted preparation method of well-crystallized VxW1-xO2(M)@SiO2 core-shell nanoparticles for VO2-based thermochromic smart coatings (VTSC) is presented. The additional annealing process reduces the defect density of the initial hydrothermally prepared VxW1-xO2(M) nanoparticles and enhances their crystallinity so that the thermochromic film based on VxW1-xO2(M)@SiO2 nanoparticles can exhibit outstanding thermochromic performance with balanced solar regulation efficiency (ΔTsol) of 17.3%, luminous transmittance (Tlum) up to 52.2%, and critical phase transition temperature (Tc) around 40.4 °C, which is very promising for practical application. Furthermore, it makes great progress in reducing Tc of VTSC to near room temperature (25.2 °C) and simutaneously maintaining excellent optical properties (ΔTsol = 14.7% and Tlum = 50.6%). Such thermochromic performance is good enough to make VTSC applicable to practical architecture.

Gastrointestinal temperature trends in football linemen during physical exertion under heat stress.

PubMed

Coris, Eric E; Mehra, Shabnam; Walz, Stephen M; Duncanson, Robert; Jennings, Jason; Nugent, Dylan; Zwygart, Kira; Pescasio, Michele

2009-06-01

Exertional heat stroke is the third leading cause of death in US athletes. Elevations in core temperature in the digestive tract (TGI) have correlated with core temperature and are possible indicators of those at increased risk of heat stroke. The primary objective was to compare a.m. vs. p.m. TGI variation in collegiate football linemen during intense "two-a-day" preseason practice. A secondary objective was to compare longitudinal TGI in offensive and defensive linemen. Cross-sectional observational study. Division I Intercollegiate Athletics Football Program. TGI was monitored during consecutive preseason sessions. TGI, heat illness, weight changes, environmental stress, and subjective symptoms. Mean TGI were 37.8°C and 38.3°C during a.m. and p.m. practices, respectively. The a.m. practices revealed higher TGI gain (1.8°C) compared to p.m. (1.4°C). The p.m. practices had higher maximum TGI than a.m. practices (39.1°C versus 38.8, P=0.0001). Mean time to maximum temperature (Tmax) was 1 hr and 30 min for a.m. and 1 hr and 22 min for p.m. practices. Offensive linemen trended toward higher mean TGI than defensive players (38.0°C vs. 36.7°C, P = 0.069). The rate of rise in TGI was significantly greater in a.m. practices. A decrease in rate of TGI rise was seen from the first to last a.m. practices of the week (P = 0.004). Significant TGI elevations in asymptomatic athletes are common in extreme heat during football practice. Intense a.m. practices in full gear result in higher net temperature gain and rate of temperature gain than p.m. practices. Offensive linemen trended toward higher TGI than defensive linemen. As players acclimatized, a decrease in the rate of TGI increase was appreciable, particularly in a.m. practices. Appreciating cumulative heat stress and variations in heat stress related to scheduling of practice is critical.

Chemical durability of high-temperature superconductor YBa2Cu3O(7-x) in aqueous environments

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Sandkuhl, Ann L.

1988-01-01

The stability of YBa2Cu3O(7-x) in water and 100-percent humidity has been investigated at three temperatures, using pH measurements, X-ray diffraction, and scanning electron microscopy. The oxide-ceramic superconductor is highly unstable; it reacts rapidly with water and degrades in moisture. Dissolution of the oxide perovskite in water is highly incongruent. The corrosion products are found to be BaCO3, CuO, O2, etc. Barium hydroxide is first formed and further reacts with atmospheric CO2 to form needle-shaped crystals of BaCO3. For any practical applications, devices made from these materials would have to be protected with an impermeable coating to prevent deterioration from atmosphere.

Lunar oxygen and metal for use in near-earth space - Magma electrolysis

NASA Technical Reports Server (NTRS)

Colson, Russell O.; Haskin, Larry A.

1990-01-01

The unique conditions on the moon, such as vacuum, absence of many reagents common on the earth, and presence of very nontraditional 'ores', suggest that a unique and nontraditional process for extracting materials from the ores may prove the most practical. An investigation has begun into unfluxed silicate electrolysis as a method for extracting oxygen, Fe, and Si from lunar regolith. The advantages of the process include simplicity of concept, absence of need to supply reagents from the earth, and low power and mass requirements for the processing plant. Disadvantages include the need for uninterrupted high temperature and the highly corrosive nature of the high-temperature silicate melts, which has made identifying suitable electrode and container materials difficult.

Practical SQUID Instrument for Nondestructive Testing

NASA Technical Reports Server (NTRS)

Tralshawala, N.; Claycomb, J. R.; Miller, John H., Jr.

1997-01-01

We report on the development of a scanning eddy-current imaging system designed to detect deep subsurface flaws in conducting materials. A high transition temperature (high-T c) superconducting quantum interference device (SQUID) magnetometer is employed to provide the required sensitivity at low frequencies, while a combination of small cylindrical high-Tc superconducting and A-metal shields enable the instrument to be scanned in a magnetically noisy environment, rather than the object under test. The shields are arranged to prevent unwanted excitation and ambient noise fields from reaching the SQUID, and to enhance spatial resolution and minimize undesirable edge effects. Thus far, the instrument has successfully detected cracks and pits through 10 layers of aluminum, with a combined thickness of 5 cm at room temperature.

Elevated relative humidity increases the incidence of boron deficiency in bedding plants

USDA-ARS?s Scientific Manuscript database

High relative humidity (RH) can cause lower concentrations of B accumulating in plants. The common greenhouse practice of controlling excess temperatures by applying mist irrigation to youngplants (plugs) results in elevated RH levels. Reports of boron (B) deficiency have become more prevalent ove...

New R-SiC extends service life in kiln furniture

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

Sonntag, A.

1997-11-01

Silicon carbide kiln furniture systems are an essential part of modern high-temperature technology. SiC ceramics have exceptional high-temperature stability and thermal shock resistance., They show no plastic deformation (creep) under mechanical load and maintain their geometry after each high-temperature cycle. Therefore, various new kiln systems with light and open setting patterns can be realized where more fired goods can be produced with less kiln furniture ballast and within shorter firing cycles. The fast-firing technology of porcelain is an opportunity for new SiC kiln furniture ceramics. The new SiC ceramic systems available include: (1) recrystallized SiC (R-SiC); (2) silicon-infiltrated reaction-bonded SiCmore » (SiSiC); and (3) nitride-bonded SiC (NSiC). The new SiC ceramics have an important production criterion in common. They show practically no shrinkage during production. This is important for the manufacture of large shapes, such as beams, rollers and setter plates, as well as tailored geometries that allow light and open kiln furniture construction. Because of the extraordinarily high thermal shock resistance, high strength and high-temperature creep stability of these SiC ceramics, delicate and precise kiln furniture configurations have been introduced. One application is the fast firing of tableware with automatic setting robots.« less

Temperature prediction in high speed bone grinding using motor PWM signal.

PubMed

Tai, Bruce L; Zhang, Lihui; Wang, Anthony C; Sullivan, Stephen; Wang, Guangjun; Shih, Albert J

2013-10-01

This research explores the feasibility of using motor electrical feedback to estimate temperature rise during a surgical bone grinding procedure. High-speed bone grinding is often used during skull base neurosurgery to remove cranial bone and approach skull base tumors through the nasal corridor. Grinding-induced heat could propagate and potentially injure surrounding nerves and arteries, and therefore, predicting the temperature in the grinding region would benefit neurosurgeons during the operation. High-speed electric motors are controlled by pulse-width-modulation (PWM) to alter the current input and thus maintain the rotational speed. Assuming full mechanical to thermal power conversion in the grinding process, PWM can be used as feedback for heat generation and temperature prediction. In this study, the conversion model was established from experiments under a variety of grinding conditions and an inverse heat transfer method to determine heat flux. Given a constant rotational speed, the heat conversion was represented by a linear function, and could predict temperature from the experimental data with less than 20% errors. Such results support the advance of this technology for practical application. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Mesoporous Germanium Anode Materials for Lithium-Ion Battery with Exceptional Cycling Stability in Wide Temperature Range.

PubMed

Choi, Sinho; Cho, Yoon-Gyo; Kim, Jieun; Choi, Nam-Soon; Song, Hyun-Kon; Wang, Guoxiu; Park, Soojin

2017-04-01

Porous structured materials have unique architectures and are promising for lithium-ion batteries to enhance performances. In particular, mesoporous materials have many advantages including a high surface area and large void spaces which can increase reactivity and accessibility of lithium ions. This study reports a synthesis of newly developed mesoporous germanium (Ge) particles prepared by a zincothermic reduction at a mild temperature for high performance lithium-ion batteries which can operate in a wide temperature range. The optimized Ge battery anodes with the mesoporous structure exhibit outstanding electrochemical properties in a wide temperature ranging from -20 to 60 °C. Ge anodes exhibit a stable cycling retention at various temperatures (capacity retention of 99% after 100 cycles at 25 °C, 84% after 300 cycles at 60 °C, and 50% after 50 cycles at -20 °C). Furthermore, full cells consisting of the mesoporous Ge anode and an LiFePO 4 cathode show an excellent cyclability at -20 and 25 °C. Mesoporous Ge materials synthesized by the zincothermic reduction can be potentially applied as high performance anode materials for practical lithium-ion batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tube wall temperature monitoring technique

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

Granton, R.L.

1985-07-01

In 1977, Monsanto and Conoco undertook the construction of a new, modern technology ethylene plant at Chocolate Bayou, near Alvin, Texas. This plant included high severity cracking furnaces with potential tube wall temperatures considerably higher than any we had previously experienced. Furnace on-stream time between decokes, a factor in the economics of plant operation, was limited by tube wall temperature, thus requiring its accurate knowledge. Earlier work with other ethylene furnaces had also demonstrated our lack of knowledge concerning high temperature measurements in a furnace firebox environment. This had to change. An outside consultant was called upon to provide amore » threeday workshop on radiant tube temperature sensing. The workshop consisted of two days of formal training in the theory and practice of temperature measurement and one day of field training. This workshop was conducted at a site away from the plant. Approximately 20 engineers (manufacturing and technical groups) attended. The major topics covered by this workshop are as follows: radiant tube temperature sensing, radiation situation of radiant tubes, g.a. method: sample calculations, noncontact sensors: methods of specifying and purchasing, thermal imager strategies, calibration of noncontact sensors, avoiding problems with noncontact sensors, optical aids to radiant tube viewing, tube temperature management and its environmental implications, and contact temperature sensors.« less

A simple differential steady-state method to measure the thermal conductivity of solid bulk materials with high accuracy.

PubMed

Kraemer, D; Chen, G

2014-02-01

Accurate measurements of thermal conductivity are of great importance for materials research and development. Steady-state methods determine thermal conductivity directly from the proportionality between heat flow and an applied temperature difference (Fourier Law). Although theoretically simple, in practice, achieving high accuracies with steady-state methods is challenging and requires rather complex experimental setups due to temperature sensor uncertainties and parasitic heat loss. We developed a simple differential steady-state method in which the sample is mounted between an electric heater and a temperature-controlled heat sink. Our method calibrates for parasitic heat losses from the electric heater during the measurement by maintaining a constant heater temperature close to the environmental temperature while varying the heat sink temperature. This enables a large signal-to-noise ratio which permits accurate measurements of samples with small thermal conductance values without an additional heater calibration measurement or sophisticated heater guards to eliminate parasitic heater losses. Additionally, the differential nature of the method largely eliminates the uncertainties of the temperature sensors, permitting measurements with small temperature differences, which is advantageous for samples with high thermal conductance values and/or with strongly temperature-dependent thermal conductivities. In order to accelerate measurements of more than one sample, the proposed method allows for measuring several samples consecutively at each temperature measurement point without adding significant error. We demonstrate the method by performing thermal conductivity measurements on commercial bulk thermoelectric Bi2Te3 samples in the temperature range of 30-150 °C with an error below 3%.

Rugged Low-Resistance Contacts To High-Tc Superconductors

NASA Technical Reports Server (NTRS)

Caton, Randall; Selim, Raouf; Byvik, Charles E.; Buoncristiani, A. Martin

1992-01-01

Newly developed technique involving use of gold makes possible to fabricate low-resistance contacts with rugged connections to high-Tc superconductors. Gold diffused into specimen of superconducting material by melting gold beads onto surface of specimen, making strong mechanical contacts. Shear strength of gold bead contacts greater than epoxy or silver paste. Practical use in high-current-carrying applications of new high-Tc materials, including superconducting magnets, long-wavelength sensors, electrical ground planes at low temperatures, and efficient transmission of power.

Superconductivity at Dawn of the Iron Age

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

Tesanovic, Zlatko

2010-03-03

Superconductivity is a stunning quantum phenomenon and among the deepest paradigms in all of physics. From fundamental theories of the universe to strange goings-on in exotic materials to medical imaging and cell phones, its conceptual and practical dimensions span a reach as wide as anything in science. Twenty-odd years ago, the discovery of copper oxides ushered in a new era of high-temperature superconductivity, and the joyous exuberance that followed - with physicists throwing everything from fancy gauge theories to synchrotron radiation into its kitchen sink - only recently began to show any signs of waning. In the spring of 2008,more » as if on cue, a new family of iron pnictide high-temperature superconductors burst on the scene, hinting at an alternative route to room-temperature superconductivity and all of its momentous consequences. Fueled by genuine excitement - and a bit of hype - the iron-based superconductivity turned into a science blockbuster of 2009. I will present a pedagogical review of this new field, contrast the physics of iron- and copper-based systems, and speculate on the microscopic origins of the two types of high-temperature superconductivity.« less

Superconductivity at Dawn of the Iron Age

ScienceCinema

Tesanovic, Zlatko

2018-01-12

Superconductivity is a stunning quantum phenomenon and among the deepest paradigms in all of physics. From fundamental theories of the universe to strange goings-on in exotic materials to medical imaging and cell phones, its conceptual and practical dimensions span a reach as wide as anything in science. Twenty-odd years ago, the discovery of copper oxides ushered in a new era of high-temperature superconductivity, and the joyous exuberance that followed - with physicists throwing everything from fancy gauge theories to synchrotron radiation into its kitchen sink - only recently began to show any signs of waning. In the spring of 2008, as if on cue, a new family of iron pnictide high-temperature superconductors burst on the scene, hinting at an alternative route to room-temperature superconductivity and all of its momentous consequences. Fueled by genuine excitement - and a bit of hype - the iron-based superconductivity turned into a science blockbuster of 2009. I will present a pedagogical review of this new field, contrast the physics of iron- and copper-based systems, and speculate on the microscopic origins of the two types of high-temperature superconductivity.

Comparison of an in-helmet temperature monitor system to rectal temperature during exercise.

PubMed

Wickwire, P Jason; Buresh, Robert J; Tis, Laurie L; Collins, Mitchell A; Jacobs, Robert D; Bell, Marla M

2012-01-01

Body temperature monitoring is crucial in helping to decrease the amount and severity of heat illnesses; however, a practical method of monitoring temperature is lacking. In response to the lack of a practical method of monitoring the temperature of athletes, Hothead Technologies developed a device (HOT), which continuously monitors an athlete's fluctuations in body temperature. HOT measures forehead temperature inside helmets. The purpose of this study was to compare HOT against rectal temperature (Trec). Male volunteers (n = 29, age = 23.5 ± 4.5 years, weight = 83.8 ± 10.4 kg, height = 180.1 ± 5.8 cm, body fat = 12.3 ± 4.5%) exercised on a treadmill at an intensity of 60-75% heart rate reserve (HRR) (wet bulb globe temperature [WBGT] = 28.7° C) until Trec reached 38.7° C. The correlation between Trec and HOT was 0.801 (R = 0.64, standard error of the estimate (SEE) = 0.25, p = 0.00). One reason for this relatively high correlation is the microclimate that HOT is monitoring. HOT is not affected by the external climate greatly because of its location in the helmet. Therefore, factors such as evaporation do not alter HOT temperature to a great degree. HOT was compared with Trec in a controlled setting, and the exercise used in this study was moderate aerobic exercise, very unlike that used in football. In a controlled laboratory setting, the relationship between HOT and Trec showed favorable correlations. However, in applied settings, helmets are repeatedly removed and replaced forcing HOT to equilibrate to forehead temperature every time the helmet is replaced. Therefore, future studies are needed to mimic how HOT will be used in field situations.

A flexible, transparent and high-performance gas sensor based on layer-materials for wearable technology

NASA Astrophysics Data System (ADS)

Zheng, Zhaoqiang; Yao, Jiandong; Wang, Bing; Yang, Guowei

2017-10-01

Gas sensors play a vital role among a wide range of practical applications. Recently, propelled by the development of layered materials, gas sensors have gained much progress. However, the high operation temperature has restricted their further application. Herein, via a facile pulsed laser deposition (PLD) method, we demonstrate a flexible, transparent and high-performance gas sensor made of highly-crystalline indium selenide (In2Se3) film. Under UV-vis-NIR light or even solar energy activation, the constructed gas sensors exhibit superior properties for detecting acetylene (C2H2) gas at room temperature. We attribute these properties to the photo-induced charger transfer mechanism upon C2H2 molecule adsorption. Moreover, no apparent degradation in the device properties is observed even after 100 bending cycles. In addition, we can also fabricate this device on rigid substrates, which is also capable to detect gas molecules at room temperature. These results unambiguously distinguish In2Se3 as a new candidate for future application in monitoring C2H2 gas at room temperature and open up new opportunities for developing next generation full-spectrum activated gas sensors.

A flexible, transparent and high-performance gas sensor based on layer-materials for wearable technology.

PubMed

Zheng, Zhaoqiang; Yao, Jiandong; Wang, Bing; Yang, Guowei

2017-10-13

Gas sensors play a vital role among a wide range of practical applications. Recently, propelled by the development of layered materials, gas sensors have gained much progress. However, the high operation temperature has restricted their further application. Herein, via a facile pulsed laser deposition (PLD) method, we demonstrate a flexible, transparent and high-performance gas sensor made of highly-crystalline indium selenide (In 2 Se 3 ) film. Under UV-vis-NIR light or even solar energy activation, the constructed gas sensors exhibit superior properties for detecting acetylene (C 2 H 2 ) gas at room temperature. We attribute these properties to the photo-induced charger transfer mechanism upon C 2 H 2 molecule adsorption. Moreover, no apparent degradation in the device properties is observed even after 100 bending cycles. In addition, we can also fabricate this device on rigid substrates, which is also capable to detect gas molecules at room temperature. These results unambiguously distinguish In 2 Se 3 as a new candidate for future application in monitoring C 2 H 2 gas at room temperature and open up new opportunities for developing next generation full-spectrum activated gas sensors.

Multifunctional Single-Phase Photocatalysts: Extended Near Infrared Photoactivity and Reliable Magnetic Recyclability

NASA Astrophysics Data System (ADS)

Li, Xiaoning; Zhu, Zhu; Li, Feng; Huang, Yan; Hu, Xiang; Huang, Haoliang; Peng, Ranran; Zhai, Xiaofang; Fu, Zhengping; Lu, Yalin

2015-10-01

A practical photocatalyst should be able to integrate together various functions including the extended solar conversion, a feasible and economic recyclability, and above the room temperature operation potential, et al., in order to fulfill the spreading application needs in nowadays. In this report, a multifunctional single-phase photocatalyst which possesses a high photoactivity extended into the near infrared region, an easy magnetic recyclability and the high temperature stability was developed by doping Co into a new layer-structured Bi7Fe3Ti3O21 material. Light absorption and photocatalytic activity of the resulted Bi7Fe3-xCoxTi3O21 photocatalyst were extended to the long wavelength as far as 800 nm. Its strong ferromagnetism above the room temperature enables the nanopowders fully recyclable in viscous solutions simply with a magnet bar in an experimental demonstration. Furthermore, such photoactivity and magnetic recyclability were heavily tested under high-temperature and high-viscosity conditions, which was intended to simulate the actual industrial environments. This work brings the bright light to a full availability of a new multifunctional photocatalyst, via integrating the much enhanced ferromagnetic, ferroelectric, optoelectronic properties, most importantly, into a single-phase structure.

Resistance of polyamide-6 against long time effects of various media at various temperatures

NASA Technical Reports Server (NTRS)

Debski, W.; Przylecka, M.

1988-01-01

During the first phase of tempering of polyamide-6, there are temporary changes which are apparently related to the lamella structure of the material. Test specimens at high temperature show that the mechanical properties of polyamide-6 are changed permanently, and mostly at 80 C. From the results of density tests and X-ray analysis, it follows that these changes depend on environmental influences and differ in gaseous and liquid media. The results of the test specimens of the mechanical properties as a function of temperature and the medium give information about the practical applications of polyamide-6.

High temperature semiconductor diode laser pumps for high energy laser applications

NASA Astrophysics Data System (ADS)

Campbell, Jenna; Semenic, Tadej; Guinn, Keith; Leisher, Paul O.; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

2018-02-01

Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. To mitigate this thermal management burden, it is desirable for diode pumps to operate efficiently at high heat sink temperatures. In this work, we have developed a scalable cooling architecture, based on jet-impingement technology with industrial coolant, for efficient cooling of diode laser bars. We have demonstrated 60% electrical-to-optical efficiency from a 9xx nm two-bar laser stack operating with propylene-glycolwater coolant, at 50 °C coolant temperature. To our knowledge, this is the highest efficiency achieved from a diode stack using 50 °C industrial fluid coolant. The output power is greater than 100 W per bar. Stacks with additional laser bars are currently in development, as this cooler architecture is scalable to a 1 kW system. This work will enable compact and robust fiber-coupled diode pump modules for high energy laser applications.

Technology and education: First approach for measuring temperature with Arduino

NASA Astrophysics Data System (ADS)

Carrillo, Alejandro

2017-04-01

This poster session presents some ideas and approaches to understand concepts of thermal equilibrium, temperature and heat in order to bulid a man-nature relationship in a harmonious and responsible manner, emphasizing the interaction between science and technology, without neglecting the relationship of the environment and society, an approach to sustainability. It is proposed the development of practices that involve the use of modern technology, of easy access and low cost to measure temperature. We believe that the Arduino microcontroller and some temperature sensors can open the doors of innovation to carry out such practices. In this work we present some results of simple practices presented to a population of students between the ages of 16 and 17 years old. The practices in this proposal are: Zero law of thermodynamics and the concept of temperature, calibration of thermometers and measurement of temperature for heating and cooling of three different substances under the same physical conditions. Finally the student is asked to make an application that involves measuring of temperature and other physical parameters. Some suggestions are: to determine the temperature at which we take some food, measure the temperature difference at different rooms of a house, housing constructions that favour optimal condition, measure the temperature of different regions, measure of temperature trough different colour filters, solar activity and UV, propose applications to understand current problems such as global warming, etc. It is concluded that the Arduino practices and electrical sensors increase the cultural horizon of the students while awaking their interest to understand their operation, basic physics and its application from a modern perspective.

High environmental temperature and preterm birth: a review of the evidence.

PubMed

Carolan-Olah, Mary; Frankowska, Dorota

2014-01-01

to examine the evidence in relation to preterm birth and high environmental temperature. this review was conducted against a background of global warming and an escalation in the frequency and severity of hot weather together with a rising preterm birth rate. electronic health databases such as: SCOPUS, MEDLINE, CINAHL, EMBASE and Maternity and Infant Care were searched for research articles, that examined preterm birth and high environmental temperature. Further searches were based on the reference lists of located articles. Keywords included a search term for preterm birth (preterm birth, preterm, premature, <37 weeks, gestation) and a search term for hot weather (heatwaves, heat-waves, global warming, climate change, extreme heat, hot weather, high temperature, ambient temperature). A total of 159 papers were retrieved in this way. Of these publications, eight met inclusion criteria. data were extracted and organised under the following headings: study design; dataset and sample; gestational age and effect of environmental heat on preterm birth. Critical Appraisal Skills Programme (CASP) guidelines were used to appraise study quality. in this review, the weight of evidence supported an association between high environmental temperature and preterm birth. However, the degree of association varied considerably, and it is not clear what factors influence this relationship. Differing definitions of preterm birth may also add to lack of clarity. preterm birth is an increasingly common and debilitating condition that affects a substantial portion of infants. Rates appear to be linked to high environmental temperature, and more especially heat stress, which may be experienced during extreme heat or following a sudden rise in temperature. When this happens, the body may be unable to adapt quickly to the change. As global warming continues, the incidence of high environmental temperature and dramatic temperature changes are also increasing. This situation makes it important that research effort is directed to understanding the degree of association and the mechanism by which high temperature and temperature increases impact on preterm birth. Research is also warranted into the development of more effective cooling practices to ameliorate the effects of heat stress. In the meantime, it is important that pregnant women are advised to take special precautions to avoid heat stress and to keep cool when there are sudden increases in temperature. Copyright © 2013 Elsevier Ltd. All rights reserved.

Characterization of photocathode dark current vs. temperature in image intensifier tube modules and intensified televisions

NASA Astrophysics Data System (ADS)

Bender, Edward J.; Wood, Michael V.; Hart, Steve; Heim, Gerald B.; Torgerson, John A.

2004-10-01

Image intensifiers (I2) have gained wide acceptance throughout the Army as the premier nighttime mobility sensor for the individual soldier, with over 200,000 fielded systems. There is increasing need, however, for such a sensor with a video output, so that it can be utilized in remote vehicle platforms, and/or can be electronically fused with other sensors. The image-intensified television (I2TV), typically consisting of an image intensifier tube coupled via fiber optic to a solid-state imaging array, has been the primary solution to this need. I2TV platforms in vehicles, however, can generate high internal heat loads and must operate in high-temperature environments. Intensifier tube dark current, called "Equivalent Background Input" or "EBI", is not a significant factor at room temperature, but can seriously degrade image contrast and intra-scene dynamic range at such high temperatures. Cooling of the intensifier's photocathode is the only practical solution to this problem. The US Army RDECOM CERDEC Night Vision & Electronic Sensors Directorate (NVESD) and Ball Aerospace have collaborated in the reported effort to more rigorously characterize intensifier EBI versus temperature. NVESD performed non-imaging EBI measurements of Generation 2 and 3 tube modules over a large range of ambient temperature, while Ball performed an imaging evaluation of Generation 3 I2TVs over a similar temperature range. The findings and conclusions of this effort are presented.

Alternate working fluids for solar air conditioning applications

NASA Technical Reports Server (NTRS)

Evans, R. D.; Beck, J. K.

1978-01-01

An experimental investigation of sixteen different refrigerant-absorbent fluid pairs has been carried out in order to determine their suitability as the working fluid in a solar-powered absorption cycle air conditioner. The criteria used in the initial selection of a refrigerant-absorbent pair included: high affinity (large negative deviation from Raoult's Law), high solubility, low specific heat, low viscosity, stability, corrosive properties, safety, and cost. For practical solar considerations of a fluid pair, refrigerants were selected with low boiling points whereas absorbent fluids were selected with a boiling point considerably above that of the refrigerant. Additional restrictions are determined by the operating temperatures of the absorber and the generator; these temperatures were specified as 100 F (39 C) and 170 F (77 C). Data are presented for a few selected pressures at the specified absorber and generator temperatures.

Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

PubMed Central

Wang, Zhi-Li; Yan, Jun-Min; Wang, Hong-Li; Ping, Yun; Jiang, Qing

2012-01-01

A highly efficient hydrogen generation from formic acid/sodium formate aqueous solution catalyzed by in situ synthesized Pd/C with citric acid has been successfully achieved at room temperature. Interestingly, the presence of citric acid during the formation and growth of the Pd nanoparticles on carbon can drastically enhance the catalytic property of the resulted Pd/C, on which the conversion and turnover frequency for decomposition of formic acid/sodium formate system can reach the highest values ever reported of 85% within 160 min and 64 mol H2 mol−1 catalyst h−1, respectively, at room temperature. The present simple, low cost, but highly efficient CO-free hydrogen generation system at room temperature is believed to greatly promote the practical application of formic acid system on fuel cells. PMID:22953041

The study on the interdependence of spray characteristics and evaporation history of fuel spray in high temperature air crossflow

NASA Astrophysics Data System (ADS)

Zhu, J. Y.; Chin, J. S.

1986-06-01

A numerical calculation method is used to predict the variation of the characteristics of fuel spray moving in a high temperature air crossflow, mainly, Sauter mean diameter SMD, droplet size distribution index N of Rosin-Rammler distribution and evaporation percentage changing with downstream distance X from the nozzle. The effect of droplet heat-up period evaporation process and forced convection are taken into full account; thus, the calculation model is a very good approximation to the process of spray evaporation in a practical combustor, such as ramjet, aero-gas turbine, liquid propellant rocket, diesel and other liquid fuel-powered combustion devices. The changes of spray characteristics N, SMD and spray evaporation percentage with air velocity, pressure, temperature, fuel injection velocity, and the initial spray parameters are presented.

A permanent-magnet rotor for a high-temperature superconducting bearing

NASA Astrophysics Data System (ADS)

Mulcahy, T. M.; Hull, J. R.; Uherka, K. L.; Abboud, R. G.; Wise, J. H.; Carnegie, D. W.

1995-06-01

Design, fabrication, and performance, of a 1/3-m dia., 10-kg flywheel rotor with only one bearing is discussed. To achieve low-loss energy storage, the rotor's segmented-ring permanent-magnet (PM) is optimized for levitation and circumferential homogeneity. The magnet's carbon composite bands enable practical energy storage.

High-pressure liquid chromatography: A brief introduction and its application in analyzing the degradation of a C-ether (Thio-ether) liquid lubricant

NASA Technical Reports Server (NTRS)

1983-01-01

The general principles of classical liquid chromatography and high pressure liquid chromatography (HPLC) are reviewed, and their advantages and disadvantages are compared. Several chromatographic techniques are reviewed, and the analytical separation of a C-ether liquid lubricant by each technique is illustrated. A practical application of HPLC is then demonstrated by analyzing a degraded C-ether liquid lubricant from full scale, high temperature bearing tests.

Fiber Optic Distributed Sensors for High-resolution Temperature Field Mapping.

PubMed

Lomperski, Stephen; Gerardi, Craig; Lisowski, Darius

2016-11-07

The reliability of computational fluid dynamics (CFD) codes is checked by comparing simulations with experimental data. A typical data set consists chiefly of velocity and temperature readings, both ideally having high spatial and temporal resolution to facilitate rigorous code validation. While high resolution velocity data is readily obtained through optical measurement techniques such as particle image velocimetry, it has proven difficult to obtain temperature data with similar resolution. Traditional sensors such as thermocouples cannot fill this role, but the recent development of distributed sensing based on Rayleigh scattering and swept-wave interferometry offers resolution suitable for CFD code validation work. Thousands of temperature measurements can be generated along a single thin optical fiber at hundreds of Hertz. Sensors function over large temperature ranges and within opaque fluids where optical techniques are unsuitable. But this type of sensor is sensitive to strain and humidity as well as temperature and so accuracy is affected by handling, vibration, and shifts in relative humidity. Such behavior is quite unlike traditional sensors and so unconventional installation and operating procedures are necessary to ensure accurate measurements. This paper demonstrates implementation of a Rayleigh scattering-type distributed temperature sensor in a thermal mixing experiment involving two air jets at 25 and 45 °C. We present criteria to guide selection of optical fiber for the sensor and describe installation setup for a jet mixing experiment. We illustrate sensor baselining, which links readings to an absolute temperature standard, and discuss practical issues such as errors due to flow-induced vibration. This material can aid those interested in temperature measurements having high data density and bandwidth for fluid dynamics experiments and similar applications. We highlight pitfalls specific to these sensors for consideration in experiment design and operation.

Conversion of salvianolic acid B into salvianolic acid A in tissues of Radix Salviae Miltiorrhizae using high temperature, high pressure and high humidity.

PubMed

Xia, Hongrui; Sun, Longru; Lou, Hongxiang; Rahman, M Mukhlesur

2014-05-15

Salvianolic acid A (Sal A), an important constituent of Radix Salviae Miltiorrhizae (RSM), is effective for the treatment of myocardial infarction (MI) and coronary heart disease due to its potential in the improvement of acute myocardial ischemia. However, its content is very low in RSM. So it is obvious to find a rich source of Sal A or to improve its content by conversion of other related components into Sal A modifying reaction conditions. In this research we focused on the conversion of Sal B into Sal A in aqueous solutions of RSM by using different reaction conditions including pH, temperature, pressure and humidity. During the reactions, the contents of Sal A, Sal B and danshensu in the RSM were analyzed by high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LCMS). The results indicated that the conversion of Sal B into Sal A in RSM tissues under the conditions of a high temperature, high pressure and high humidity was efficient and thereby, was readily utilized to prepare rich Sal A materials in practice. Copyright © 2014 Elsevier GmbH. All rights reserved.

Time for a change to assess and evaluate body temperature in clinical practice.

PubMed

Sund-Levander, Märtha; Grodzinsky, Ewa

2009-08-01

The definition of normal body temperature as 37 degrees C still is considered the norm worldwide, but in practice there is a widespread confusion of the evaluation of body temperature, especially in elderly individuals. In this paper, we discuss the relevance of normal body temperature as 37 degrees C and consequences in clinical practice. Our conclusion is that body temperature should be evaluated in relation to the individual variability and that the best approach is to use the same site, and an unadjusted mode without adjustments to other sites. If the baseline value is not known, it is important to notice that frail elderly individuals are at risk of a low body temperature. In addition, what should be regarded as fever is closely related to what is considered as normal body temperature. That is, as normal body temperature shows individual variations, it is reasonable that the same should hold true for the febrile range.

Investigations of different doping concentration of phosphorus and boron into silicon substrate on the variable temperature Raman characteristics

NASA Astrophysics Data System (ADS)

Li, Xiaoli; Ding, Kai; Liu, Jian; Gao, Junxuan; Zhang, Weifeng

2018-01-01

Different doped silicon substrates have different device applications and have been used to fabricate solar panels and large scale integrated circuits. The thermal transport in silicon substrates are dominated by lattice vibrations, doping type, and doping concentration. In this paper, a variable-temperature Raman spectroscopic system is applied to record the frequency and linewidth changes of the silicon peak at 520 cm-1 in five chips of silicon substrate with different doping concentration of phosphorus and boron at the 83K to 1473K temperature range. The doping has better heat sensitive to temperature on the frequency shift over the low temperature range from 83K to 300K but on FWHM in high temperature range from 300K to 1473K. The results will be helpful for fundamental study and practical applications of silicon substrates.

Estimating stellar effective temperatures and detected angular parameters using stochastic particle swarm optimization

NASA Astrophysics Data System (ADS)

Zhang, Chuan-Xin; Yuan, Yuan; Zhang, Hao-Wei; Shuai, Yong; Tan, He-Ping

2016-09-01

Considering features of stellar spectral radiation and sky surveys, we established a computational model for stellar effective temperatures, detected angular parameters and gray rates. Using known stellar flux data in some bands, we estimated stellar effective temperatures and detected angular parameters using stochastic particle swarm optimization (SPSO). We first verified the reliability of SPSO, and then determined reasonable parameters that produced highly accurate estimates under certain gray deviation levels. Finally, we calculated 177 860 stellar effective temperatures and detected angular parameters using data from the Midcourse Space Experiment (MSX) catalog. These derived stellar effective temperatures were accurate when we compared them to known values from literatures. This research makes full use of catalog data and presents an original technique for studying stellar characteristics. It proposes a novel method for calculating stellar effective temperatures and detecting angular parameters, and provides theoretical and practical data for finding information about radiation in any band.

Formulation Development of High Strength Gel System and Evaluation on Profile Control Performance for High Salinity and Low Permeability Fractured Reservoir

PubMed Central

Zhang, Chengli; Qu, Guodong

2017-01-01

For the large pores and cracks of reservoirs with low temperatures, high salinity, and low permeability, a new type of high strength gel ABP system is developed in this paper. The defects of conventional gels such as weak gel strength, no gelling, and easy dehydration are overcome under the conditions of low temperature and high salinity. The temperature and salt resistance, plugging characteristics, and EOR of the gel system are studied. Under the condition of 32°C and 29500 mg/L salinity, the ABP system formulation is for 0.3% crosslinking agent A + 0.09% coagulant B + 3500 mg/L polymer solution P. The results show that when the temperature was increased, the delayed crosslinking time of the system was shortened and the gel strength was increased. The good plugging characteristics of the ABP system were reached, and the plugging rate was greater than 99% in cores with different permeability. A good profile control performance was achieved, and the recovery rate was improved by 19.27% on the basis of water flooding. In the practical application of the gel system, the salinity of formation water and the permeability of fractures are necessary to determine the appropriate formulation. PMID:28592971

3D architecture of a graphene/CoMoO(4) composite for asymmetric supercapacitors usable at various temperatures.

PubMed

Jiang, Yaru; Zheng, Xin; Yan, Xiaoqin; Li, Yong; Zhao, Xuan; Zhang, Yue

2017-05-01

Designing and optimizing the electrode materials and studying the electrochemical performance or cycle life of the supercapacitor under different working conditions are crucial to its practical application. Herein, we proposed a rational design of 3D-graphene/CoMoO 4 nanoplates by a facile two-step hydrothermal method. Owing to the high electron transfer rate of graphene and the high activity of the CoMoO 4 nanoplates, the three-dimensional electrode architectures achieved remarkable electrochemical performances with high areal specific capacitance (1255.24F/g at 1A/g) and superior cycling stability (91.3% of the original specific capacitance after 3000 cycles at 1A/g). The all-solid-state asymmetric supercapacitor composed of 3D-graphene/CoMoO 4 and activated carbon (AC) exhibited a specific capacitance of 109F/g at 0.2A/g and an excellent cycling stability with only 12.1% of the initial specific capacitance off after 3000 cycles at 2A/g. The effects of temperature and charge-discharge current densities on the charge storage capacity of the supercapacitor were also investigated in detail for practical applications. Copyright © 2017 Elsevier Inc. All rights reserved.

High-Energy/Power and Low-Temperature Cathode for Sodium-Ion Batteries: In Situ XRD Study and Superior Full-Cell Performance.

PubMed

Guo, Jin-Zhi; Wang, Peng-Fei; Wu, Xing-Long; Zhang, Xiao-Hua; Yan, Qingyu; Chen, Hong; Zhang, Jing-Ping; Guo, Yu-Guo

2017-09-01

Sodium-ion batteries (SIBs) are still confronted with several major challenges, including low energy and power densities, short-term cycle life, and poor low-temperature performance, which severely hinder their practical applications. Here, a high-voltage cathode composed of Na 3 V 2 (PO 4 ) 2 O 2 F nano-tetraprisms (NVPF-NTP) is proposed to enhance the energy density of SIBs. The prepared NVPF-NTP exhibits two high working plateaux at about 4.01 and 3.60 V versus the Na + /Na with a specific capacity of 127.8 mA h g -1 . The energy density of NVPF-NTP reaches up to 486 W h kg -1 , which is higher than the majority of other cathode materials previously reported for SIBs. Moreover, due to the low strain (≈2.56% volumetric variation) and superior Na transport kinetics in Na intercalation/extraction processes, as demonstrated by in situ X-ray diffraction, galvanostatic intermittent titration technique, and cyclic voltammetry at varied scan rates, the NVPF-NTP shows long-term cycle life, superior low-temperature performance, and outstanding high-rate capabilities. The comparison of Ragone plots further discloses that NVPF-NTP presents the best power performance among the state-of-the-art cathode materials for SIBs. More importantly, when coupled with an Sb-based anode, the fabricated sodium-ion full-cells also exhibit excellent rate and cycling performances, thus providing a preview of their practical application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flash Diffusivity Technique Applied to Individual Fibers

NASA Technical Reports Server (NTRS)

Mayeaux, Brian; Yowell, Leonard; Wang, Hsin

2007-01-01

A variant of the flash diffusivity technique has been devised for determining the thermal diffusivities, and thus the thermal conductivities, of individual aligned fibers. The technique is intended especially for application to nanocomposite fibers, made from narrower fibers of polyphenylene benzobisthiazole (PBZT) and carbon nanotubes. These highly aligned nanocomposite fibers could exploit the high thermal conductivities of carbon nanotubes for thermal-management applications. In the flash diffusivity technique as practiced heretofore, one or more heat pulse(s) is (are) applied to the front face of a plate or disk material specimen and the resulting time-varying temperature on the rear face is measured. Usually, the heat pulse is generated by use of a xenon flash lamp, and the variation of temperature on the rear face is measured by use of an infrared detector. The flash energy is made large enough to produce a usefully high temperature rise on the rear face, but not so large as to significantly alter the specimen material. Once the measurement has been completed, the thermal diffusivity of the specimen is computed from the thickness of the specimen and the time dependence of the temperature variation on the rear face. Heretofore, the infrared detector used in the flash diffusivity technique has been a single-point detector, which responds to a spatial average of the thermal radiation from the rear specimen surface. Such a detector cannot distinguish among regions of differing diffusivity within the specimen. Moreover, two basic assumptions of the thermaldiffusivity technique as practiced heretofore are that the specimen is homogeneous and that heat flows one-dimensionally from the front to the rear face. These assumptions are not valid for an inhomogeneous (composite) material.

Managing fever in children: a national survey of parents' knowledge and practices in France.

PubMed

Bertille, Nathalie; Fournier-Charrière, Elisabeth; Pons, Gérard; Chalumeau, Martin

2013-01-01

Identifying targets to improve parental practices for managing fever in children is the first step to reducing the overloaded healthcare system related to this common symptom. We aimed to study parents' knowledge and practices and their determinants in managing fever symptoms in children in France as compared with current recommendations. We conducted an observational national study between 2007 and 2008 of French general practitioners, primary care pediatricians and pharmacists. These healthcare professionals (HPs) were asked to include 5 consecutive patients from 1 month to 12 years old with fever for up to 48 hr who were accompanied by a family member. Parents completed a questionnaire about their knowledge of fever in children and their attitudes about the current fever episode. We used a multilevel logistic regression model to assess the joint effects of patient- and HP-level variables. In all, 1,534 HPs (participation rate 13%) included 6,596 children. Parental concordance with current recommendations for temperature measurement methods, the threshold for defining fever, and physical (oral hydration, undressing, room temperature) and drug treatment was 89%, 61%, 15%, and 23%, respectively. Multivariate multi-level analyses revealed a significant HP effect. In general, high concordance with recommendations was associated with high educational level of parents and the HP consulted being a pediatrician. In France, parents' knowledge and practices related to managing fever symptoms in children frequently differ from recommendations. Targeted health education interventions are needed to effectively manage fever symptoms in children.

Managing Fever in Children: A National Survey of Parents' Knowledge and Practices in France

PubMed Central

Bertille, Nathalie; Fournier-Charrière, Elisabeth; Pons, Gérard; Chalumeau, Martin

2013-01-01

Introduction Identifying targets to improve parental practices for managing fever in children is the first step to reducing the overloaded healthcare system related to this common symptom. We aimed to study parents' knowledge and practices and their determinants in managing fever symptoms in children in France as compared with current recommendations. Methods We conducted an observational national study between 2007 and 2008 of French general practitioners, primary care pediatricians and pharmacists. These healthcare professionals (HPs) were asked to include 5 consecutive patients from 1 month to 12 years old with fever for up to 48 hr who were accompanied by a family member. Parents completed a questionnaire about their knowledge of fever in children and their attitudes about the current fever episode. We used a multilevel logistic regression model to assess the joint effects of patient- and HP-level variables. Results In all, 1,534 HPs (participation rate 13%) included 6,596 children. Parental concordance with current recommendations for temperature measurement methods, the threshold for defining fever, and physical (oral hydration, undressing, room temperature) and drug treatment was 89%, 61%, 15%, and 23%, respectively. Multivariate multi-level analyses revealed a significant HP effect. In general, high concordance with recommendations was associated with high educational level of parents and the HP consulted being a pediatrician. Conclusions In France, parents' knowledge and practices related to managing fever symptoms in children frequently differ from recommendations. Targeted health education interventions are needed to effectively manage fever symptoms in children. PMID:24391772

Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering temperature and concentration measurements using two different picosecond-duration probes.

PubMed

Kearney, Sean P; Scoglietti, Daniel J; Kliewer, Christopher J

2013-05-20

A hybrid fs/ps pure-rotational CARS scheme is characterized in furnace-heated air at temperatures from 290 to 800 K. Impulsive femtosecond excitation is used to prepare a rotational Raman coherence that is probed with a ps-duration beam generated from an initially broadband fs pulse that is bandwidth limited using air-spaced Fabry-Perot etalons. CARS spectra are generated using 1.5- and 7.0-ps duration probe beams with corresponding coarse and narrow spectral widths. The spectra are fitted using a simple phenomenological model for both shot-averaged and single-shot measurements of temperature and oxygen mole fraction. Our single-shot temperature measurements exhibit high levels of precision and accuracy when the spectrally coarse 1.5-ps probe beam is used, demonstrating that high spectral resolution is not required for thermometry. An initial assessment of concentration measurements in air is also provided, with best results obtained using the higher resolution 7.0-ps probe. This systematic assessment of the hybrid CARS technique demonstrates its utility for practical application in low-temperature gas-phase systems.

Understanding local degradation of cycled Ni-rich cathode materials at high operating temperature for Li-ion batteries

NASA Astrophysics Data System (ADS)

Hwang, Sooyeon; Kim, Dong Hyun; Chung, Kyung Yoon; Chang, Wonyoung

2014-09-01

We utilize transmission electron microscopy in conjunction with electron energy loss spectroscopy to investigate local degradation that occurs in LixNi0.8Co0.15Al0.05O2 cathode materials (NCA) after 30 cycles with cutoff voltages of 4.3 V and 4.8 V at 55 °C. NCA has a homogeneous crystallographic structure before electrochemical reactions; however, we observed that 30 cycles of charge/discharge reactions induced inhomogeneity in the crystallographic and electronic structures and also introduced porosity particularly at surface area. These changes were more noticeable in samples cycled with higher cutoff voltage of 4.8 V. Effect of operating temperature was further examined by comparing electronic structures of oxygen of the NCA particles cycled at both room temperature and 55 °C. The working temperature has a greater impact on the NCA cathode materials at a cutoff voltage of 4.3 V that is the practical the upper limit voltage in most applications, while a cutoff voltage of 4.8 V is high enough to cause surface degradation even at room temperature.

Toward large-scale solar energy systems with peak concentrations of 20,000 suns

NASA Astrophysics Data System (ADS)

Kribus, Abraham

1997-10-01

The heliostat field plays a crucial role in defining the achievable limits for central receiver system efficiency and cost. Increasing system efficiency, thus reducing the reflective area and system cost, can be achieved by increasing the concentration and the receiver temperature. The concentration achievable in central receiver plants, however, is constrained by current heliostat technology and design practices. The factors affecting field performance are surface and tracking errors, astigmatism, shadowing, blocking and dilution. These are geometric factors that can be systematically treated and reduced. We present improvements in collection optics and technology that may boost concentration (up to 20,000 peak), achievable temperature (2,000 K), and efficiency in solar central receiver plants. The increased performance may significantly reduce the cost of solar energy in existing applications, and enable solar access to new ultra-high-temperature applications, such as: future gas turbines approaching 60% combined cycle efficiency; high-temperature thermo-chemical processes; and gas-dynamic processes.

Rapid-Rate Compression Testing of Sheet Materials at High Temperatures

NASA Technical Reports Server (NTRS)

Bernett, E. C.; Gerberich, W. W.

1961-01-01

This Report describes the test equipment that was developed and the procedures that were used to evaluate structural sheet-material compression properties at preselected constant strain rates and/or loads. Electrical self-resistance was used to achieve a rapid heating rate of 200 F/sec. Four materials were tested at maximum temperatures which ranged from 600 F for the aluminum alloy to 2000 F for the Ni-Cr-Co iron-base alloy. Tests at 0.1, 0.001, and 0.00001 in./in./sec showed that strain rate has a major effect on the measured strength, especially at the high temperatures. The tests, under conditions of constant temperature and constant compression stress, showed that creep deformation can be a critical factor even when the time involved is on the order of a few seconds or less. The theoretical and practical aspects of rapid-rate compression testing are presented, and suggestions are made regarding possible modifications of the equipment which would improve the over-all capabilities.

Development of intermediate temperature sodium nickel chloride rechargeable batteries using conventional polymer sealing technologies

NASA Astrophysics Data System (ADS)

Chang, Hee Jung; Lu, Xiaochuan; Bonnett, Jeff F.; Canfield, Nathan L.; Son, Sori; Park, Yoon-Cheol; Jung, Keeyoung; Sprenkle, Vincent L.; Li, Guosheng

2017-04-01

Developing advanced and reliable electrical energy storage systems is critical to fulfill global energy demands and stimulate the growth of renewable energy resources. Sodium metal halide batteries have been under serious consideration as a low cost alternative energy storage device for stationary energy storage systems. Yet, there are number of challenges to overcome for the successful market penetration, such as high operating temperature and hermetic sealing of batteries that trigger an expensive manufacturing process. Here we demonstrate simple, economical and practical sealing technologies for Na-NiCl2 batteries operated at an intermediate temperature of 190 °C. Conventional polymers are implemented in planar Na-NiCl2 batteries after a prescreening test, and their excellent compatibilities and durability are demonstrated by a stable performance of Na-NiCl2 battery for more than 300 cycles. The sealing methods developed in this work will be highly beneficial and feasible for prolonging battery cycle life and reducing manufacturing cost for Na-based batteries at elevated temperatures (<200 °C).

One-step synthesis of multi-emission carbon nanodots for ratiometric temperature sensing

NASA Astrophysics Data System (ADS)

Nguyen, Vanthan; Yan, Lihe; Xu, Huanhuan; Yue, Mengmeng

2018-01-01

Measuring temperature with greater precision at localized small length scales or in a nonperturbative manner is a necessity in widespread applications, such as integrated photonic devices, micro/nano electronics, biology, and medical diagnostics. To this context, use of nanoscale fluorescent temperature probes is regarded as the most promising method for temperature sensing because they are noninvasive, accurate, and enable remote micro/nanoscale imaging. Here, we propose a novel ratiometric fluorescent sensor for nanothermometry using carbon nanodots (C-dots). The C-dots were synthesized by one-step method using femtosecond laser ablation and exhibit unique multi-emission property due to emissions from abundant functional groups on its surface. The as-prepared C-dots demonstrate excellent ratiometric temperature sensing under single wavelength excitation that achieves high temperature sensitivity with a 1.48% change per °C ratiometric response over wide-ranging temperature (5-85 °C) in aqueous buffer. The ratiometric sensor shows excellent reversibility and stability, holding great promise for the accurate measurement of temperature in many practical applications.

A review of catalyst-enhanced magnesium hydride as a hydrogen storage material

NASA Astrophysics Data System (ADS)

Webb, C. J.

2015-09-01

Magnesium hydride remains an attractive hydrogen storage material due to the high hydrogen capacity and low cost of production. A high activation energy and poor kinetics at practical temperatures for the pure material have driven research into different additives to improve the sorption properties. This review details the development of catalytic additives and their effect on the activation energy, kinetics and thermodynamic properties of magnesium hydride.

High-Efficiency Helical Coil Electromagnetic Launcher and High Power Hall-Effect Switch

DTIC Science & Technology

2008-02-29

also given that demonstrate significant launcher performance benefits by super-cooling the armature (i.e., using liquid nitrogen ). 14. ABSTRACT... liquid nitrogen temperatures). A computer model for a magnetically-controlled Hall-effect switch is developed. The model is constructed in the PSpice...of super-cooling is demonstrated with liquid nitrogen cooling and indicates super-cooled EML operation is desirable if cryo-cooling is practical for

On the Henry constant and isosteric heat at zero loading in gas phase adsorption.

PubMed

Do, D D; Nicholson, D; Do, H D

2008-08-01

The Henry constant and the isosteric heat of adsorption at zero loading are commonly used as indicators of the strength of the affinity of an adsorbate for a solid adsorbent. It is assumed that (i) they are observable in practice, (ii) the Van Hoff's plot of the logarithm of the Henry constant versus the inverse of temperature is always linear and the slope is equal to the heat of adsorption, and (iii) the isosteric heat of adsorption at zero loading is either constant or weakly dependent on temperature. We show in this paper that none of these three points is necessarily correct, first because these variables might not be observable since they are outside the range of measurability; second that the linearity of the Van Hoff plot breaks down at very high temperature, and third that the isosteric heat versus loading is a strong function of temperature. We demonstrate these points using Monte Carlo integration and Monte Carlo simulation of adsorption of various gases on a graphite surface. Another issue concerning the Henry constant is related to the way the adsorption excess is defined. The most commonly used equation is the one that assumes that the void volume is the volume extended all the way to a boundary passing through the centres of the outermost solid atoms. With this definition the Henry constant can become negative at high temperatures. Although adsorption at these temperatures may not be practical because of the very low value of the Henry constant, it is more useful to define the Henry constant in such a way that it is always positive at all temperatures. Here we propose the use of the accessible volume; the volume probed by the adsorbate when it is in nonpositive regions of the potential, to calculate the Henry constant.

Influence of temperature fluctuations during cryopreservation on vital parameters, differentiation potential, and transgene expression of placental multipotent stromal cells.

PubMed

Pogozhykh, Denys; Pogozhykh, Olena; Prokopyuk, Volodymyr; Kuleshova, Larisa; Goltsev, Anatoliy; Blasczyk, Rainer; Mueller, Thomas

2017-03-11

Successful implementation of rapidly advancing regenerative medicine approaches has led to high demand for readily available cellular suspensions. In particular, multipotent stromal cells (MSCs) of placental origin have shown therapeutic efficiency in the treatment of numerous pathologies of varied etiology. Up to now, cryopreservation is the only effective way to preserve the viability and unique properties of such cells in the long term. However, practical biobanking is often associated with repeated temperature fluctuations or interruption of a cold chain due to various technical, transportation, and stocking events. While biochemical processes are expected to be suspended during cryopreservation, such temperature fluctuations may lead to accumulation of stress as well as to periodic release of water fractions in the samples, possibly leading to damage during long-term storage. In this study, we performed a comprehensive analysis of changes in cell survival, vital parameters, and differentiation potential, as well as transgene expression of placental MSCs after temperature fluctuations within the liquid nitrogen steam storage, mimicking long-term preservation in practical biobanking, transportation, and temporal storage. It was shown that viability and metabolic parameters of placental MSCs did not significantly differ after temperature fluctuations in the range from -196 °C to -100 °C in less than 20 cycles in comparison to constant temperature storage. However, increasing the temperature range to -80 °C as well as increasing the number of cycles leads to significant lowering of these parameters after thawing. The number of apoptotic changes increases depending on the number of cycles of temperature fluctuations. Besides, adhesive properties of the cells after thawing are significantly compromised in the samples subjected to temperature fluctuations during storage. Differentiation potential of placental MSCs was not compromised after cryopreservation with constant end temperatures or with temperature fluctuations. However, regulation of various genes after cryopreservation procedures significantly varies. Interestingly, transgene expression was not compromised in any of the studied samples. Alterations in structural and functional parameters of placental MSCs after long-term preservation should be considered in practical biobanking due to potential temperature fluctuations in samples. At the same time, differentiation potential and transgene expression are not compromised during studied storage conditions, while variation in gene regulation is observed.

A nickel metal hydride battery for electric vehicles

NASA Astrophysics Data System (ADS)

Ovshinsky, S. R.; Fetcenko, M. A.; Ross, J.

1993-04-01

An efficient battery is the key technological element to the development of practical electric vehicles. The science and technology of a nickel metal hydride battery, which stores hydrogen in the solid hydride phase and has high energy density, high power, long life, tolerance to abuse, a wide range of operating temperature, quick-charge capability, and totally sealed maintenance-free operation, is described. A broad range of multi-element metal hydride materials that use structural and compositional disorder on several scales of length has been engineered for use as the negative electrode in this battery. The battery operates at ambient temperature, is made of nontoxic materials, and is recyclable. Demonstration of the manufacturing technology has been achieved.

Practical solution of plastic deformation problems in elastic-plastic range

NASA Technical Reports Server (NTRS)

Mendelson, A; Manson, S

1957-01-01

A practical method for solving plastic deformation problems in the elastic-plastic range is presented. The method is one of successive approximations and is illustrated by four examples which include a flat plate with temperature distribution across the width, a thin shell with axial temperature distribution, a solid cylinder with radial temperature distribution, and a rotating disk with radial temperature distribution.

Guidelines for maintaining and managing the vaccine cold chain.

PubMed

2003-10-24

In February 2002, the Advisory Committee on Immunization Practices (ACIP) and American Academy of Family Physicians (AAFP) released their revised General Recommendations on Immunization, which included recommendations on the storage and handling of immunobiologics. Because of increased concern over the potential for errors with the vaccine cold chain (i.e., maintaining proper vaccine temperatures during storage and handling to preserve potency), this notice advises vaccine providers of the importance of proper cold chain management practices. This report describes proper storage units and storage temperatures, outlines appropriate temperature-monitoring practices, and recommends steps for evaluating a temperature-monitoring program. The success of efforts against vaccine-preventable diseases is attributable in part to proper storage and handling of vaccines. Exposure of vaccines to temperatures outside the recommended ranges can affect potency adversely, thereby reducing protection from vaccine-preventable diseases. Good practices to maintain proper vaccine storage and handling can ensure that the full benefit of immunization is realized.

Magnetic slippery extreme icephobic surfaces

PubMed Central

Irajizad, Peyman; Hasnain, Munib; Farokhnia, Nazanin; Sajadi, Seyed Mohammad; Ghasemi, Hadi

2016-01-01

Anti-icing surfaces have a critical footprint on daily lives of humans ranging from transportation systems and infrastructure to energy systems, but creation of these surfaces for low temperatures remains elusive. Non-wetting surfaces and liquid-infused surfaces have inspired routes for the development of icephobic surfaces. However, high freezing temperature, high ice adhesion strength, and high cost have restricted their practical applications. Here we report new magnetic slippery surfaces outperforming state-of-the-art icephobic surfaces with a ice formation temperature of −34 °C, 2–3 orders of magnitude higher delay time in ice formation, extremely low ice adhesion strength (≈2 Pa) and stability in shear flows up to Reynolds number of 105. In these surfaces, we exploit the magnetic volumetric force to exclude the role of solid–liquid interface in ice formation. We show that these inexpensive surfaces are universal and can be applied to all types of solids (no required micro/nano structuring) with no compromise to their unprecedented properties. PMID:27824053

Magnetic radiation shielding - An idea whose time has returned?

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1991-01-01

One solution to the problem of shielding crew from particulate radiation in space is to use active electromagnetic shielding. Practical types of shield include the magnetic shield, in which a strong magnetic field diverts charged particles from the crew region, and the magnetic/electrostatic plasma shield, in which an electrostatic field shields the crew from positively charged particles, while a magnetic field confines electrons from the space plasma to provide charge neutrality. Advances in technology include high-strength composite materials, high-temperature superconductors, numerical computational solutions to particle transport in electromagnetic fields, and a technology base for construction and operation of large superconducting magnets. These advances make electromagnetic shielding a practical alternative for near-term future missions.

Chemical vapor deposition modeling for high temperature materials

NASA Technical Reports Server (NTRS)

Gokoglu, Suleyman A.

1992-01-01

The formalism for the accurate modeling of chemical vapor deposition (CVD) processes has matured based on the well established principles of transport phenomena and chemical kinetics in the gas phase and on surfaces. The utility and limitations of such models are discussed in practical applications for high temperature structural materials. Attention is drawn to the complexities and uncertainties in chemical kinetics. Traditional approaches based on only equilibrium thermochemistry and/or transport phenomena are defended as useful tools, within their validity, for engineering purposes. The role of modeling is discussed within the context of establishing the link between CVD process parameters and material microstructures/properties. It is argued that CVD modeling is an essential part of designing CVD equipment and controlling/optimizing CVD processes for the production and/or coating of high performance structural materials.

SAMOS - A Decade of High-Quality, Underway Meteorological and Oceanographic Data from Research Vessels

NASA Astrophysics Data System (ADS)

Smith, S. R.; Rolph, J.; Briggs, K.; Elya, J. L.; Bourassa, M. A.

2016-02-01

The authors will describe the successes and lessons learned from the Shipboard Automated Meteorological and Oceanographic System (SAMOS) initiative. Over the past decade, SAMOS has acquired, quality controlled, and distributed underway surface meteorological and oceanographic observations from nearly 40 oceanographic research vessels. Research vessels provide underway observations at high-temporal frequency (1-minute sampling interval) that include navigational (position, course, heading, and speed), meteorological (air temperature, humidity, wind, surface pressure, radiation, rainfall), and oceanographic (surface sea temperature and salinity) samples. Vessels recruited to the SAMOS initiative collect a high concentration of data within the U.S. continental shelf, around Hawaii and the islands of the tropical Pacific, and frequently operate well outside routine shipping lanes, capturing observations in extreme ocean environments (Southern, Arctic, South Atlantic, and South Pacific oceans) desired by the air-sea exchange, modeling, and satellite remote sensing communities. The presentation will highlight the data stewardship practices of the SAMOS initiative. Activities include routine automated and visual data quality evaluation, feedback to vessel technicians and operators regarding instrumentation errors, best practices for instrument siting and exposure on research vessels, and professional development activities for research vessel technicians. Best practices for data, metadata, and quality evaluation will be presented. We will discuss ongoing efforts to expand data services to enhance interoperability between marine data centers. Data access and archival protocols will also be presented, including how these data may be referenced and accessed via NCEI.

Forest defoliator outbreaks under climate change: effects on the frequency and severity of outbreaks of five pine insect pests.

PubMed

Haynes, Kyle J; Allstadt, Andrew J; Klimetzek, Dietrich

2014-06-01

To identify general patterns in the effects of climate change on the outbreak dynamics of forest-defoliating insect species, we examined a 212-year record (1800-2011) of outbreaks of five pine-defoliating species (Bupalus piniarius, Panolis flammea, Lymantria monacha, Dendrolimus pini, and Diprion pini) in Bavaria, Germany for the evidence of climate-driven changes in the severity, cyclicity, and frequency of outbreaks. We also accounted for historical changes in forestry practices and examined effects of past insecticide use to suppress outbreaks. Analysis of relationships between severity or occurrence of outbreaks and detrended measures of temperature and precipitation revealed a mixture of positive and negative relationships between temperature and outbreak activity. Two moth species (P. flammea and Dendrolimus pini) exhibited lower outbreak activity following years or decades of unusually warm temperatures, whereas a sawfly (Diprion pini), for which voltinism is influenced by temperature, displayed increased outbreak occurrence in years of high summer temperatures. We detected only one apparent effect of precipitation, which showed Dendrolimus pini outbreaks tending to follow drought. Wavelet analysis of outbreak time series suggested climate change may be associated with collapse of L. monacha and Dendrolimus pini outbreak cycles (loss of cyclicity and discontinuation of outbreaks, respectively), but high-frequency cycles for B. piniarius and P. flammea in the late 1900s. Regional outbreak severity was generally not related to past suppression efforts (area treated with insecticides). Recent shifts in forestry practices affecting tree species composition roughly coincided with high-frequency outbreak cycles in B. piniarius and P. flammea but are unlikely to explain the detected relationships between climate and outbreak severity or collapses of outbreak cycles. Our results highlight both individualistic responses of different pine-defoliating species to climate changes and some patterns that are consistent across defoliator species in this and other forest systems, including collapsing of population cycles. © 2014 John Wiley & Sons Ltd.

High-temperature optically activated GaAs power switching for aircraft digital electronic control

NASA Technical Reports Server (NTRS)

Berak, J. M.; Grantham, D. H.; Swindal, J. L.; Black, J. F.; Allen, L. B.

1983-01-01

Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas.

Challenges and Progress in the Development of High-Temperature Shape Memory Alloys Based on NiTiX Compositions for High-Force Actuator Applications

NASA Technical Reports Server (NTRS)

Padula, Santo, II; Bigelow, Glen; Noebe, Ronald; Gaydosh, Darrell; Garg, Anita

2006-01-01

Interest in high-temperature shape memory alloys (HTSMA) has been growing in the aerospace, automotive, process control, and energy industries. However, actual materials development has seriously lagged component design, with current commercial NiTi alloys severely limited in their temperature capability. Additions of Pd, Pt, Au, Hf, and Zr at levels greater than 10 at.% have been shown to increase the transformation temperature of NiTi alloys, but with few exceptions, the shape memory behavior (strain recovery) of these NiTiX systems has been determined only under stress free conditions. Given the limited amount of basic mechanical test data and general lack of information regarding the work attributes of these materials, a program to investigate the mechanical behavior of potential HTSMAs, with transformation temperatures between 100 and 500 C, was initiated. This paper summarizes the results of studies, focusing on both the practical temperature limitations for ternary TiNiPd and TiNiPt systems based on the work output of these alloys and the ability of these alloys to undergo repeated thermal cycling under load without significant permanent deformation or "walking". These issues are ultimately controlled by the detwinning stress of the martensite and resistance to dislocation slip of the individual martensite and austenite phases. Finally, general rules that govern the development of useful, high work output, next-generation HTSMA materials, based on the lessons learned in this work, will be provided

Experimental evaluation of main emissions during coal processing waste combustion.

PubMed

Dmitrienko, Margarita A; Legros, Jean C; Strizhak, Pavel A

2018-02-01

The total volume of the coal processing wastes (filter cakes) produced by Russia, China, and India is as high as dozens of millions of tons per year. The concentrations of CO and CO 2 in the emissions from the combustion of filter cakes have been measured directly for the first time. They are the biggest volume of coal processing wastes. There have been many discussions about using these wastes as primary or secondary components of coal-water slurries (CWS) and coal-water slurries containing petrochemicals (CWSP). Boilers have already been operationally tested in Russia for the combustion of CWSP based on filter cakes. In this work, the concentrations of hazardous emissions have been measured at temperatures ranging from 500 to 1000°С. The produced CO and CO 2 concentrations are shown to be practically constant at high temperatures (over 900°С) for all the coal processing wastes under study. Experiments have shown the feasibility to lowering the combustion temperatures of coal processing wastes down to 750-850°С. This provides sustainable combustion and reduces the CO and CO 2 emissions 1.2-1.7 times. These relatively low temperatures ensure satisfactory environmental and energy performance of combustion. Using CWS and CWSP instead of conventional solid fuels significantly reduces NO x and SO x emissions but leaves CO and CO 2 emissions practically at the same level as coal powder combustion. Therefore, the environmentally friendly future (in terms of all the main atmospheric emissions: CO, CO 2 , NO x , and SO x ) of both CWS and CWSP technologies relies on low-temperature combustion. Copyright © 2017 Elsevier Ltd. All rights reserved.

High electromechanical strain and enhanced temperature characteristics in lead-free (Na,Bi)TiO3-BaTiO3 thin films on Si substrates.

PubMed

Tanaka, Yoshiaki; Okamoto, Shoji; Hashimoto, Kazuya; Takayama, Ryoichi; Harigai, Takakiyo; Adachi, Hideaki; Fujii, Eiji

2018-05-18

Here, we demonstrate the high electromechanical strain and enhanced temperature characteristics in the c-axis-oriented lead-free (Na,Bi)TiO 3 -BaTiO 3 (NBT-BT) polycrystalline thin film prepared on Si substrates by rf magnetron sputtering. The effective transverse piezoelectric coefficient, e 31 * , estimated from the electromechanical strain measured under high electric field, reaches a high level of -12.5 C/m 2 , and is comparable to those of conventional Pb(Zr,Ti)O 3 films. In-situ X-ray diffraction measurement and electron diffraction analysis revealed the electromechanical strain of the NBT-BT film to originate predominantly in elongation of the tetragonal (P4bm) crystal lattice in the c-axis direction. In addition to the large e 31 * , the NBT-BT film exhibits enhanced permittivity maximum temperature, T m , of ~400 °C and no depolarization below T m , as compared to bulk NBT-BT having T m ≈ 300 °C and a depolarization temperature of ~100 °C. We conclude that the enhancement of temperature characteristics is associated with the distorted P4bm crystal lattice formed by deposition-induced stress and defects. We believe that the present study paves the way for practical applications of lead-free piezoelectric thin films in electromechanical devices.

Reliable, Low-Cost, Low-Weight, Non-Hermetic Coating for MCM Applications

NASA Technical Reports Server (NTRS)

Jones, Eric W.; Licari, James J.

2000-01-01

Through an Air Force Research Laboratory sponsored STM program, reliable, low-cost, low-weight, non-hermetic coatings for multi-chip-module(MCK applications were developed. Using the combination of Sandia Laboratory ATC-01 test chips, AvanTeco's moisture sensor chips(MSC's), and silicon slices, we have shown that organic and organic/inorganic overcoatings are reliable and practical non-hermetic moisture and oxidation barriers. The use of the MSC and unpassivated ATC-01 test chips provided rapid test results and comparison of moisture barrier quality of the overcoatings. The organic coatings studied were Parylene and Cyclotene. The inorganic coatings were Al2O3 and SiO2. The choice of coating(s) is dependent on the environment that the device(s) will be exposed to. We have defined four(4) classes of environments: Class I(moderate temperature/moderate humidity). Class H(high temperature/moderate humidity). Class III(moderate temperature/high humidity). Class IV(high temperature/high humidity). By subjecting the components to adhesion, FTIR, temperature-humidity(TH), pressure cooker(PCT), and electrical tests, we have determined that it is possible to reduce failures 50-70% for organic/inorganic coated components compared to organic coated components. All materials and equipment used are readily available commercially or are standard in most semiconductor fabrication lines. It is estimated that production cost for the developed technology would range from $1-10/module, compared to $20-200 for hermetically sealed packages.

Significantly enhanced piezoelectricity in low-temperature sintered Aurivillius-type ceramics with ultrahigh Curie temperature of 800 °C

NASA Astrophysics Data System (ADS)

Cai, Kai; Huang, Chengcheng; Guo, Dong

2017-04-01

We report an Aurivillius-type piezoelectric ceramic (Ca1-2x (LiCe) x Bi4Ti3.99Zn0.01O15) that has an ultrahigh Curie temperature (T c) around 800 °C and a significantly enhanced piezoelectric coefficient (d 33), comparable to that of textured ceramics fabricated using the complicated templating method. Surprisingly, the highest d 33 of 26 pC/N was achieved at an unexpectedly low sintering temperature (T s) of only 920 °C (~200 °C lower than usual) despite the non-ideal density. Study of different synthesized samples indicates that a relatively low T s is crucial for suppressing Bi evaporation and abnormal grain growth, which are indispensable for high resistivity and effective poling due to decreased carrier density and restricted anisotropic conduction. Because the layered structure is sensitive to lattice defects, controlled Bi loss is considered to be crucial for maintaining structural order and spontaneous polarization. This low-T s system is very promising for practical applications due to its high piezoelectricity, low cost and high reproducibility. Contrary to our usual understanding, the results reveal that a delicate balance of density, Bi loss and grain morphology achieved by adjusting the sintering temperature is crucial for the enhancing performance in Aurivillius-type high-T c ceramics.

Plasma chemistry for inorganic materials

NASA Technical Reports Server (NTRS)

Matsumoto, O.

1980-01-01

Practical application of plasma chemistry to the development of inorganic materials using both low temperature and warm plasmas are summarized. Topics cover: the surface nitrification and oxidation of metals; chemical vapor deposition; formation of minute oxide particles; the composition of oxides from chloride vapor; the composition of carbides and nitrides; freezing high temperature phases by plasma arc welding and plasma jet; use of plasma in the development of a substitute for petroleum; the production of silicon for use in solar cell batteries; and insulating the inner surface of nuclear fusion reactor walls.

Evaluating the Impact of Global Warming on Water Balance of Maize by High-precision Controlled Experiment and MLCan model

NASA Astrophysics Data System (ADS)

Ma, Y.; Song, X.; Kumar, P.; Wu, Y.; Woo, D.; Le, P. V.; Ma, C.

2016-12-01

Increased temperature affects the agricultural hydrologic cycle not only by changing precipitation levels, evapotranspiration and the magnitude and timing of run-off, but also by impacting water flows and soil water dynamics. Accurate prediction of hydrologic change under global warming requires high-precision experiment and mathematical model to determine water interaction between interfaces in the soil-plant-atmosphere continuum. In this study, the weighting lysimeter and chamber were coupled to monitor water balance component dynamics of maize under controlled ambient temperature and elevated temperature of 2°C conditions. A mechanistic multilayer canopy-soil-root system model (MLCan) was used to predict hydrologic fluxes variation under different elevated temperature scenarios after calibration with experimental results. The results showed that maize growth period reduced 8 days under increased temperature of 2°C. The mean daily evapotranspiration, soil water storage change, and drainage was 2.66 mm, -2.75 mm, and 0.22 mm under controlled temperature condition, respectively. When temperature was elevated by 2°C, the average daily ET for maize significantly increased about 6.7% (p<0.05). However, there were non-significant impacts of increased temperature on the daily soil water storage change and drainage (p>0.05). Quantification of changes in water balance components induced by temperature increase for maize is critical for optimizing irrigation water management practices and improving water use efficiency.

Multiple Waveband Temperature Sensor (MWTS)

NASA Technical Reports Server (NTRS)

Bandara, Sumith V.; Gunapala, Sarath; Wilson, Daniel; Stirbl, Robert; Blea, Anthony; Harding, Gilbert

2006-01-01

This slide presentation reviews the development of Multiple Waveband Temperature Sensor (MWTS). The MWTS project will result in a highly stable, monolithically integrated, high resolution infrared detector array sensor that records registered thermal imagery in four infrared wavebands to infer dynamic temperature profiles on a laser-irradiated ground target. An accurate surface temperature measurement of a target in extreme environments in a non-intrusive manner is required. The development challenge is to: determine optimum wavebands (suitable for target temperatures, nature of the targets and environments) to measure accurate target surface temperature independent of the emissivity, integrate simultaneously readable multiband Quantum Well Infrared Photodetectors (QWIPs) in a single monolithic focal plane array (FPA) sensor and to integrate the hardware/software and system calibration for remote temperature measurements. The charge was therefore to develop and demonstrate a multiband infrared imaging camera with the detectors simultaneously sensitive to multiple distinct color bands for front surface temperature measurements Wavelength ( m) measurements. Amongst the requirements are: that the measurement system will not affect target dynamics or response to the laser irradiation and that the simplest criterion for spectral band selection is to choose those practically feasible spectral bands that create the most contrast between the objects or scenes of interest in the expected environmental conditions. There is in the presentation a review of the modeling and simulation of multi-wave infrared temperature measurement and also a review of the detector development and QWIP capacities.

Extreme temperature trends in major cropping systems and their relation to agricultural land use change

NASA Astrophysics Data System (ADS)

Mueller, N. D.; Butler, E. E.; McKinnon, K. A.; Rhines, A. N.; Tingley, M.; Siebert, S.; Holbrook, N. M.; Huybers, P. J.

2015-12-01

High temperature extremes during the growing season can reduce agricultural production. At the same time, agricultural practices can modify temperatures by altering the surface energy budget. Here we investigate growing season climate trends in major cropping systems and their relationship with agricultural land use change. In the US Midwest, 100-year trends exhibit a transition towards more favorable conditions, with cooler summer temperature extremes and increased precipitation. Statistically significant correspondence is found between the cooling pattern and trends in cropland intensification, as well as with trends towards greater irrigated land over a small subset of the domain. Land conversion to cropland, often considered an important influence on historical temperatures, is not significantly associated with cooling. We suggest that cooling is primarily associated with agricultural intensification increasing the potential for evapotranspiration, consistent with our finding that cooling trends are greatest for the highest temperature percentiles, and that increased evapotranspiration generally leads to greater precipitation. Temperatures over rainfed croplands show no cooling trend during drought conditions, consistent with evapotranspiration requiring adequate soil moisture, and implying that modern drought events feature greater warming as baseline cooler temperatures revert to historically high extremes. Preliminary results indicate these relationships between temperature extremes, irrigation, and intensification are also observed in other major summer cropping systems, including northeast China, Argentina, and the Canadian Prairies.

An evaluation of 2 new devices for nasal high-flow gas therapy.

PubMed

Waugh, Jonathan B; Granger, Wesley M

2004-08-01

The traditional nasal cannula with bubble humidifier is limited to a maximum flow of 6 L/min to minimize the risk of complications. We conducted a bench study of 2 new Food and Drug Administration-approved nasal cannula/humidifier products designed to deliver at flows> 6 L/min. Using a digital psychrometer we measured the relative humidity and temperature of delivered gas from each device, at 5 L/min increments over the specified functional high-flow range. The Salter Labs unit achieved 72.5-78.7% relative humidity (5-15 L/min range) at ambient temperature (21-23 degrees C). The Vapotherm device achieved 99.9% relative humidity at a temperature setting of 37 degrees C (5-40 L/min). Both devices meet minimum humidification standards and offer practical new treatment options. The patient-selection criteria are primarily the severity of the patient's condition and cost.

High-temperature self-circulating thermoacoustic heat exchanger

NASA Astrophysics Data System (ADS)

Backhaus, S.; Swift, G. W.; Reid, R. S.

2005-07-01

Thermoacoustic and Stirling engines and refrigerators use heat exchangers to transfer heat between the oscillating flow of their thermodynamic working fluids and external heat sources and sinks. An acoustically driven heat-exchange loop uses an engine's own pressure oscillations to steadily circulate its own thermodynamic working fluid through a physically remote high-temperature heat source without using moving parts, allowing for a significant reduction in the cost and complexity of thermoacoustic and Stirling heat exchangers. The simplicity and flexibility of such heat-exchanger loops will allow thermoacoustic and Stirling machines to access diverse heat sources and sinks. Measurements of the temperatures at the interface between such a heat-exchange loop and the hot end of a thermoacoustic-Stirling engine are presented. When the steady flow is too small to flush out the mixing chamber in one acoustic cycle, the heat transfer to the regenerator is excellent, with important implications for practical use.

On the Measurement of Power Law Creep Parameters from Instrumented Indentation

NASA Astrophysics Data System (ADS)

Sudharshan Phani, P.; Oliver, W. C.; Pharr, G. M.

2017-11-01

Recently the measurement of the creep response of materials at small scales has received renewed interest largely because the equipment required to perform high-temperature nanomechanical testing has become available to an increasing number of researchers. Despite that increased access, there remain several significant experimental and modeling challenges in small-scale mechanical testing at elevated temperatures that are as yet unresolved. In this regard, relating the creep response observed with high-temperature instrumented indentation experiments to macroscopic uniaxial creep response is of great practical value. In this review, we present an overview of various methods currently being used to measure creep with instrumented indentation, with a focus on geometrically self-similar indenters, and their relative merits and demerits from an experimental perspective. A comparison of the various methods to use those instrumented indentation results to predict the uniaxial power law creep response of a wide range of materials will be presented to assess their validity.

Effect of simultaneous variation in temperature and ammonia concentration on percent fertilization and hatching in Crassostrea ariakensis.

PubMed

Hui, Wang; Jiahui, Liu; Hongshuai, Yang; Jin, Liu; Zhigang, Liu

2014-04-01

The combined effects of temperature and ammonia concentration on the percent fertilization and percent hatching in Crassostrea ariakensis were examined under laboratory conditions using the central composite design and response surface methodology. The results indicated: (1) The linear effects of temperature and ammonia concentration on the percent fertilization were significant (P<0.05), and the quadratic effects were highly significant (P<0.01). The interactive effect between temperature and ammonia concentration on the percent fertilization was not significant (P>0.05). (2) The linear effect of temperature on the percent hatching was highly significant (P<0.01), and that of ammonia concentration was nonsignificant (P>0.05). The quadratic effects of temperature and ammonia concentration on the percent hatching were highly significant (P<0.01). The interaction on the percent hatching was not significant (P>0.05). Temperature was more important than ammonia in influencing the fertilization and hatching in C. ariakensis. (3) The model equations of the percent fertilization and hatching towards temperature and ammonia concentration were established, with the coefficients of determination R(2)=99.4% and 99.76%, respectively. Through the lack-of-fit test, these models were of great adequacy. The predictive coefficients of determination for the two model equations were as high as 94.6% and 98.03%, respectively, showing that they could be used for practical projection. (4) Via the statistical simultaneous optimization technique, the optimal factor level combination, i.e., 25°C/0.038mgmL(-1), was derived, at which the greatest percent fertilization 95.25% and hatching 83.26% was achieved, with the desirability being 97.81%. Our results may provide advantageous guidelines for the successful reproduction of C. ariakensis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Blackbody for metrological control of ear thermometers

NASA Astrophysics Data System (ADS)

Cárdenas-García, D.; Méndez-Lango, E.

2013-09-01

Body temperature is an important parameter in medical practice, and most of health diagnoses are made based upon measured temperature values. Non-contact measurements are attractive to both patients and physicians, and ear thermometers (ET) are part of the set of infrared thermometers for medical applications. ETs sense the tympanic membrane temperature which best represents body temperature. They take advantage of the natural high effective emissivity cavity that is formed as radiation source. To calibrate or to check the performance of ETs, we designed a high-emissivity spherical cavity as a blackbody source which can be placed in a dry block oven. Although the blackbody cavity can have any shape, we decided to build it spherical because its effective emissivity can be easily calculated in a closed form. The cavity is made of Aluminum to take advantage of its high thermal conductivity while its inner side is covered with a black paint to increase the cavity effective emissivity. Based on paint emissivity measurements and the geometrical shape, we calculated that the cavity has an effective emissivity higher than 0.999. Blackbody temperature is measured with a calibrated contact thermometer placed inside the bottom wall of the cavity. We present the design of the cavity, the experimental setup, and results of three commercial ETs compared with this cavity.

Electric energy production by particle thermionic-thermoelectric power generators

NASA Technical Reports Server (NTRS)

Oettinger, P. E.

1980-01-01

Thermionic-thermoelectric power generators, composed of a thin layer of porous, low work function material separating a heated emitter electrode and a cooler collector electrode, have extremely large Seebeck coefficients of over 2 mV/K and can provide significant output power. Preliminary experiments with 20-micron thick (Ba Sr Ca)O coatings, limited by evaporative loss to temperatures below 1400 K, have yielded short circuit current densities of 500 mA/sq cm and power densities of 60 mW/ sq cm. Substantially more output is expected with cesium-coated refractory oxide particle coatings operating at higher temperatures. Practical generators will have thermal-to-electrical efficiencies of 10 to 20%. Further increases can be gained by cascading these high-temperature devices with lower temperature conventional thermoelectric generators.

High temperature superconductors applications in telecommunications

NASA Technical Reports Server (NTRS)

Kumar, A. Anil; Li, Jiang; Zhang, Ming Fang

1995-01-01

The purpose of this paper is twofold: (1) to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and (2) to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices - obvious advantages versus practical difficulties - needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models - a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B) - shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance - conductivity, surface resistance and attenuation constant - will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T(sub c) superconductors.

High temperature superconductors applications in telecommunications

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

Kumar, A.A.; Li, J.; Zhang, M.F.

1994-12-31

The purpose of this paper is twofold: to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices-obvious advantages versus practical difficulties-needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data formore » such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models-a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B)-shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance-conductivity, surface resistance and attenuation constant-will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T{sub c} superconductors.« less

Practical approaches for application of resistance type strain gages on high temperature composites

NASA Technical Reports Server (NTRS)

Moore, Thomas C., Sr.

1991-01-01

Four major areas of interest with respect to utilizing strain gages on carbon/carbon (with SiC surfaces) and titanium matrix composites are addressed. Strain gage and adhesive combinations on carbon/carbon (C/C) at temperatures from minus 190 C to to 540 C, half-bridge gaging for reducing apparent strain on C/C using Poisson's ratio and bending configurations, a review of the 'field installation' techniques developed for gaging a C/C hypersonic generic elevon, and results of initial strain gaging efforts on titanium matrix composites are discussed. Current research in developing techniques for increasing the maximum temperature for strain gages on carbon/carbon are reviewed.

Metal-coated Bragg grating reflecting fibre

NASA Astrophysics Data System (ADS)

Chamorovskiy, Yu. K.; Butov, O. V.; Kolosovskiy, A. O.; Popov, S. M.; Voloshin, V. V.; Vorob'ev, I. L.; Vyatkin, M. Yu.

2017-03-01

High-temperature optical fibres (OF) with fibre Bragg gratings (FBG) arrays written over a long length and in-line metal coating have been made for the first time. The optical parameters of the FBG arrays were tested by the optical frequency domain reflectometer (OFDR) method in a wide temperature range, demonstrating no degradation in reflection at heating up to 600 °C for a fibre with Al coating. The mechanical strength of the developed fibre was practically the same as "ordinary" OF with similar coating, showing the absence of the influence of FBG writing process on fibre strength. Further experiments are necessary to evaluate the possibility of further increases in the operational temperature range.

Temperature distribution analysis of tissue water vaporization during microwave ablation: experiments and simulations.

PubMed

Ai, Haiming; Wu, Shuicai; Gao, Hongjian; Zhao, Lei; Yang, Chunlan; Zeng, Yi

2012-01-01

The temperature distribution in the region near a microwave antenna is a critical factor that affects the entire temperature field during microwave ablation of tissue. It is challenging to predict this distribution precisely, because the temperature in the near-antenna region varies greatly. The effects of water vaporisation and subsequent tissue carbonisation in an ex vivo porcine liver were therefore studied experimentally and in simulations. The enthalpy and high-temperature specific absorption rate (SAR) of liver tissues were calculated and incorporated into the simulation process. The accuracy of predictions for near-field temperatures in our simulations has reached the level where the average maximum error is less than 5°C. In addition, a modified thermal model that accounts for water vaporisation and the change in the SAR distribution pattern is proposed and validated with experiment. The results from this study may be useful in the clinical practice of microwave ablation and can be applied to predict the temperature field in surgical planning.

Molecular Collision Processes in Gases and at Surfaces.

DTIC Science & Technology

1987-12-12

expansion and reached the collisionless flow regime so that no further changes in state (due to collision) can occur; (2) Those in which two free jets...this free jet experiment seems to exhibit. (5) To us these results fairly cry out for further investigation. In another variation on the corona...produce I high dimer concentrations is to combine high pressures with low temperatures, in diametric opposition to the conventional practice we have just

Vacuum microelectronics for beam power and rectennas

NASA Technical Reports Server (NTRS)

Gray, Henry F.

1989-01-01

Vacuum Microelectronic devices can be described as vacuum transistors or micro-miniature vacuum tubes, as one chooses. The fundamental reason behind this new technology is the very large current densities available from field emitters, namely as high as 10(8) A/sq cm. Array current densities as high as 1000 A/sq cm have been measured. Total electron transit times from source to drain for 1 micron feature size devices have been predicted to be about 150fs. This very short transit time implies the possibility of submillimeter wave transmitters and rectennas in devices which can operate with reasonably high voltages and which are small in size and are lightweight. In addition, they are expected to be extremely radiation hard and very temperature insensitive. That is, they are expected to have radiation hardness characteristics similar to vacuum tubes, and both the high temperature and low temperature limits should be determined by the package. That is, there should be no practical intrinsic temperature or carrier freezeout problems for devices based on metals or composites. But the technology is difficult to implement at the present time because it is based on 300 to 500 angstrom radius field emitters which must be relatively uniform. There is also the need to understand the non-equilibrium transport physics in the near-surface regions of the field emitters.

High Precision Temperature Insensitive Strain Sensor Based on Fiber-Optic Delay

PubMed Central

Yang, Ning; Su, Jun; Fan, Zhiqiang; Qiu, Qi

2017-01-01

A fiber-optic delay based strain sensor with high precision and temperature insensitivity was reported, which works on detecting the delay induced by strain instead of spectrum. In order to analyze the working principle of this sensor, the elastic property of fiber-optic delay was theoretically researched and the elastic coefficient was measured as 3.78 ps/km·με. In this sensor, an extra reference path was introduced to simplify the measurement of delay and resist the cross-effect of environmental temperature. Utilizing an optical fiber stretcher driven by piezoelectric ceramics, the performance of this strain sensor was tested. The experimental results demonstrate that temperature fluctuations contribute little to the strain error and that the calculated strain sensitivity is as high as 4.75 με in the range of 350 με. As a result, this strain sensor is proved to be feasible and practical, which is appropriate for strain measurement in a simple and economical way. Furthermore, on basis of this sensor, the quasi-distributed measurement could be also easily realized by wavelength division multiplexing and wavelength addressing for long-distance structure health and security monitoring. PMID:28468323

An effective iodide formulation for killing Bacillus and Geobacillus spores over a wide temperature range.

PubMed

Kida, N; Mochizuki, Y; Taguchi, F

2004-01-01

To develop a sporicidal reagent which shows potent activity against bacterial spores not only at ambient temperatures but also at low temperatures. Suspension tests on spores of Bacillus and Geobacillus were conducted with the reagent based on a previously reported agent (N. Kida, Y. Mochizuki and F. Taguchi, Microbiology and Immunology 2003; 47: 279-283). The modified reagent (tentatively designated as the KMT reagent) was composed of 50 mmol l(-1) EDTA-2Na, 50 mmol l(-1) ferric chloride hexahydrate (FeCl(3).6H(2)O), 50 mmol l(-1) potassium iodide (KI) and 50% ethanol in 0.85% NaCl solution at pH 0.3. The KMT reagent showed significant sporicidal activity against three species of Bacillus and Geobacillus spores over a wide range of temperature. The KMT reagent had many practical advantages, i.e. activity was much less affected by organic substances than was sodium hypochlorite, it did not generate any harmful gas and it was stable for a long period at ambient temperatures. The mechanism(s) of sporicidal activity of the KMT reagent was considered to be based on active iodine species penetrating the spores with enhanced permeability of the spore cortex by a synergistic effect of acid, ethanol and generated active oxygen. The data suggest that the KMT reagent shows potent sporicidal activity over a wide range temperatures and possesses many advantages for practical applications. The results indicate development of a highly applicable sporicidal reagent against Bacillus and Geobacillus spores.

The cryogenic wind tunnel for high Reynolds number testing. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Kilgore, R. A.

1974-01-01

Experiments performed at the NASA Langley Research Center in a cryogenic low-speed continuous-flow tunnel and in a cryogenic transonic continuous-flow pressure tunnel have demonstrated the predicted changes in Reynolds number, drive power, and fan speed with temperature, while operating with nitrogen as the test gas. The experiments have also demonstrated that cooling to cryogenic temperatures by spraying liquid nitrogen directly into the tunnel circuit is practical and that tunnel temperature can be controlled within very close limits. Whereas most types of wind tunnel could operate with advantage at cryogenic temperatures, the continuous-flow fan-driven tunnel is particularly well suited to take full advantage of operating at these temperatures. A continuous-flow fan-driven cryogenic tunnel to satisfy current requirements for test Reynolds number can be constructed and operated using existing techniques. Both capital and operating costs appear acceptable.

Sessile multidroplets and salt droplets under high tangential electric fields

PubMed Central

Xie, Guoxin; He, Feng; Liu, Xiang; Si, Lina; Guo, Dan

2016-01-01

Understanding the interaction behaviors between sessile droplets under imposed high voltages is very important in many practical situations, e.g., microfluidic devices and the degradation/aging problems of outdoor high-power applications. In the present work, the droplet coalescence, the discharge activity and the surface thermal distribution response between sessile multidroplets and chloride salt droplets under high tangential electric fields have been investigated with infrared thermography, high-speed photography and pulse current measurement. Obvious polarity effects on the discharge path direction and the temperature change in the droplets in the initial stage after discharge initiation were observed due to the anodic dissolution of metal ions from the electrode. In the case of sessile aligned multidroplets, the discharge path direction could affect the location of initial droplet coalescence. The smaller unmerged droplet would be drained into the merged large droplet as a result from the pressure difference inside the droplets rather than the asymmetric temperature change due to discharge. The discharge inception voltages and the temperature variations for two salt droplets closely correlated with the ionization degree of the salt, as well as the interfacial electrochemical reactions near the electrodes. Mechanisms of these observed phenomena were discussed. PMID:27121926

Optimization of acidic extraction of astaxanthin from Phaffia rhodozyma *

PubMed Central

Ni, Hui; Chen, Qi-he; He, Guo-qing; Wu, Guang-bin; Yang, Yuan-fan

2008-01-01

Optimization of a process for extracting astaxanthin from Phaffia rhodozyma by acidic method was investigated, regarding several extraction factors such as acids, organic solvents, temperature and time. Fractional factorial design, central composite design and response surface methodology were used to derive a statistically optimal model, which corresponded to the following optimal condition: concentration of lactic acid at 5.55 mol/L, ratio of ethanol to yeast dry weight at 20.25 ml/g, temperature for cell-disruption at 30 °C, and extraction time for 3 min. Under this condition, astaxanthin and the total carotenoids could be extracted in amounts of 1294.7 μg/g and 1516.0 μg/g, respectively. This acidic method has advantages such as high extraction efficiency, low chemical toxicity and no special requirement of instruments. Therefore, it might be a more feasible and practical method for industrial practice. PMID:18196613

Simultaneous measurement of magnetic field and temperature based on an etched TCFMI cascaded with an FBG

NASA Astrophysics Data System (ADS)

Yan, Guofeng; Zhang, Liang; He, Sailing

2016-04-01

In this paper, a dual-parameter measurement scheme based on an etched thin core fiber modal interferometer (TCMI) cascaded with a fiber Bragg grating (FBG) is proposed and experimentally demonstrated for simultaneous measurement of magnetic field and temperature. The magnetic field and temperature responses of the packaged TCFMI were first investigated, which showed that the magnetic field sensitivity could be highly enhanced by decreasing of the TCF diameter and the temperature-cross sensitivities were up to 3-7 Oe/°C at 1550 nm. Then, the theoretical analysis and experimental demonstration of the proposed dual-parameter sensing scheme were conducted. Experimental results show that, the reflection of the FBG has a magnetic field intensity and temperature sensitivities of -0.017 dB/Oe and 0.133 dB/°C, respectively, while the Bragg wavelength of the FBG is insensitive to magnetic field and has a temperature sensitivity of 13.23 pm/°C. Thus by using the sensing matrix method, the intensity of the magnetic field and the temperature variance can be measured, which enables magnetic field sensing under strict temperature environments. In the on-off time response test, the fabricated sensor exhibited high repeatability and short response time of ∼19.4 s. Meanwhile the reflective sensing probe type is more compact and practical for applications in hard-to-reach conditions.

A versatile route to polymer-reinforced, broadband antireflective and superhydrophobic thin films without high-temperature treatment.

PubMed

Ren, Tingting; Geng, Zhi; He, Junhui; Zhang, Xiaojie; He, Jin

2017-01-15

Broadband high transmittance, good mechanical robustness as well as simple and low temperature fabrication are three important aspects that dictate the practical applications of superhydrophobic thin films, especially on organic substrates. However, it has proved difficult to meet these challenges. In the present work, superhydrophobic thin films were prepared by first dip-coating solid silica nanoparticles, then spray-coating hollow silica nanoparticles, followed by spray-coating mesoporous silica nanosheets & poly(vinyl alcohol) (PVA), and eventually chemical vapor deposition of 1H,1H,2H,2H-perflurooctyltriethoxysilane (POTS) at 90°C. The optimized thin film has a maximum transmittance of 96.0% in the wavelength range of 300-2500nm and a WCA of 164° and a RA of 1°. The thin film also shows good mechanical robustness toward water droplet impact test, sand impact abrasion test and tape adhesion tests, which results from PVA as a binder, the formation of covalent bond between the hydroxyl group of PVA and the ethoxy group of POTS and the chemical inertness of CC, CF bonds of POTS molecules. To our best knowledge, it is the first example where antireflective and superhydrophobic thin films of excellent mechanical robustness were realized at low temperature on organic substrates (PMMA, PC). The current work would provide a promising route to meet the challenges in practical applications simultaneously posed by the requirements of broadband antireflection, good mechanical robustness as well as simple and low temperature fabrication of superhydrophobic thin films. Copyright © 2016 Elsevier Inc. All rights reserved.

Red meat and poultry, cooking practices, genetic susceptibility and risk of prostate cancer: results from a multiethnic case–control study

PubMed Central

Stern, Mariana C.

2012-01-01

Red meat, processed and unprocessed, has been considered a potential prostate cancer (PCA) risk factor; epidemiological evidence, however, is inconclusive. An association between meat intake and PCA may be due to potent chemical carcinogens that are generated when meats are cooked at high temperatures. We investigated the association between red meat and poultry intake and localized and advanced PCA taking into account cooking practices and polymorphisms in enzymes that metabolize carcinogens that accumulate in cooked meats. We analyzed data for 1096 controls, 717 localized and 1140 advanced cases from the California Collaborative Prostate Cancer Study, a multiethnic, population-based case–control study. We examined nutrient density-adjusted intake of red meat and poultry and tested for effect modification by 12 SNPs and 2 copy number variants in 10 carcinogen metabolism genes: GSTP1, PTGS2, CYP1A2, CYP2E1, EPHX1, CYP1B1, UGT1A6, NAT2, GSTM1 and GSTT1. We observed a positive association between risk of advanced PCA and high intake of red meat cooked at high temperatures (trend P = 0.026), cooked by pan-frying (trend P = 0.035), and cooked until well-done (trend P = 0.013). An inverse association was observed for baked poultry and advanced PCA risk (trend P = 0.023). A gene-by-diet interaction was observed between an SNP in the PTGS2 gene and the estimated levels of meat mutagens (interaction P = 0.008). Our results support a role for carcinogens that accumulate in meats cooked at high temperatures as potential PCA risk factors, and may support a role for heterocyclic amines (HCAs) in PCA etiology. PMID:22822096

High temperature solar photon engines. [heat engines for terrestrial and space-based solar power plants

NASA Technical Reports Server (NTRS)

Hertzberg, A.; Decher, R.; Mattick, A. T.; Lau, C. V.

1978-01-01

High temperature heat engines designed to make maximum use of the thermodynamic potential of concentrated solar radiation are described. Plasmas between 2000 K and 4000 K can be achieved by volumetric absorption of radiation in alkali metal vapors, leading to thermal efficiencies up to 75% for terrestrial solar power plants and up to 50% for space power plants. Two machines capable of expanding hot plasmas using practical technology are discussed. A binary Rankine cycle uses fluid mechanical energy transfer in a device known as the 'Comprex' or 'energy exchanger.' The second machine utilizes magnetohydrodynamics in a Brayton cycle for space applications. Absorption of solar energy and plasma radiation losses are investigated for a solar superheater using potassium vapor.

High-temperature superconductor antenna investigations

NASA Technical Reports Server (NTRS)

Karasack, Vincent G.

1990-01-01

The use of superconductors to increase antenna radiation efficiency and gain is examined. Although the gain of all normal-metal antennas can be increased through the use of superconductors, some structures have greater potential for practical improvement than others. Some structures suffer a great degradation in bandwidth when replaced with superconductors, while for others the improvement in efficiency is trivial due to the minimal contribution of the conductor loss mechanism to the total losses, or the already high efficiency of the structure. The following antennas and related structures are discussed: electrically small antennas, impedance matching of antennas, microstrip antennas, microwave and millimeter-wave antenna arrays, and superdirective arrays. The greatest potential practical improvements occur for large microwave and millimeter-wave arrays and the impedance matching of antennas.

Variations in incubator temperature and humidity management: a survey of current practice.

PubMed

Deguines, C; Décima, P; Pelletier, A; Dégrugilliers, L; Ghyselen, L; Tourneux, P

2012-03-01

To describe and assess routine procedures and practices for incubator temperature and humidity management in France in 2009. A questionnaire was sent to all the 186 neonatal care units in France. The questionnaire return rate was 86%. Seventy-five per cent of the units preferred skin servo-control to air temperature control in routine practice. Air temperature control was mainly used for infants with a gestational age of more than 28 weeks and aged over 7 days of life. In general, thermal management decisions did not depend on the infant's age but were based on a protocol applied specifically by each unit. All units humidified the incubator air, but there was a large difference between the lowest and highest reported humidity values (45% and 100% assumed to be a maximal value, respectively). More than 65% of the units used a fixed humidity value, rather than a variable, protocol-derived value. We observed large variations in incubator temperature and humidity management approaches from one neonatal care unit to another. There is a need for more evidence to better inform practice. A task force should be formed to guide clinical practice. © 2011 The Author(s)/Acta Paediatrica © 2011 Foundation Acta Paediatrica.

Nanostructured Electrode Materials Derived from Metal-Organic Framework Xerogels for High-Energy-Density Asymmetric Supercapacitor.

PubMed

Mahmood, Asif; Zou, Ruqiang; Wang, Qingfei; Xia, Wei; Tabassum, Hassina; Qiu, Bin; Zhao, Ruo

2016-01-27

This work successfully demonstrates metal-organic framework (MOF) derived strategy to prepare nanoporous carbon (NPC) with or without Fe3O4/Fe nanoparticles by the optimization of calcination temperature as highly active electrode materials for asymmetric supercapacitors (ASC). The nanostructured Fe3O4/Fe/C hybrid shows high specific capacitance of 600 F/g at a current density of 1 A/g and excellent capacitance retention up to 500 F/g at 8 A/g. Furthermore, hierarchically NPC with high surface area also obtained from MOF gels displays excellent electrochemical performance of 272 F/g at 2 mV/s. Considering practical applications, aqueous ASC (aASC) was also assembled, which shows high energy density of 17.496 Wh/kg at the power density of 388.8 W/kg. The high energy density and excellent capacity retention of the developed materials show great promise for the practical utilization of these energy storage devices.

Nikitin et al, ;Methane high-temperature partition function from contact transformations and variational calculations;, Journal of Quantitative Spectroscopy & Radiative Transfer Vol 167 (2015) pp. 53-63

NASA Astrophysics Data System (ADS)

Nikitin, A. V.; Krishna, B. M.; Rey, M.; Tashkun, S. A.; Tyuterev, Vl. G.

2017-09-01

Table 4 of Ref [1] did not contain enough digits to reproduce the fitted Q(T) values for practical applications. The corrected table is given below. This does not affect other Tables and Figures or the conclusions of [1].

Mechanism of removal of undesirable residual amylase, insoluble starch, and select colorants from refinery streams by powdered activated carbons

USDA-ARS?s Scientific Manuscript database

There is a need in the world-wide sugar industry to find a practical and economical solution to remove or inactivate residual alpha-amylases that are high temperature stable from factory or refinery streams. A survey of refineries that used amylase and had activated carbon systems for decolorization...

Mechanical degradation temperature of waste storage materials

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

Fink, M.C.; Meyer, M.L.

1993-05-13

Heat loading analysis of the Solid Waste Disposal Facility (SWDF) waste storage configurations show the containers may exceed 90{degrees}C without any radioactive decay heat contribution. Contamination containment is primarily controlled in TRU waste packaging by using multiple bag layers of polyvinyl chloride and polyethylene. Since literature values indicate that these thermoplastic materials can begin mechanical degradation at 66{degrees}C, there was concern that the containment layers could be breached by heating. To better define the mechanical degradation temperature limits for the materials, a series of heating tests were conducted over a fifteen and thirty minute time interval. Samples of a low-densitymore » polyethylene (LDPE) bag, a high-density polyethylene (HDPE) high efficiency particulate air filter (HEPA) container, PVC bag and sealing tape were heated in a convection oven to temperatures ranging from 90 to 185{degrees}C. The following temperature limits are recommended for each of the tested materials: (1) low-density polyethylene -- 110{degrees}C; (2) polyvinyl chloride -- 130{degrees}C; (3) high-density polyethylene -- 140{degrees}C; (4) sealing tape -- 140{degrees}C. Testing with LDPE and PVC at temperatures ranging from 110 to 130{degrees}C for 60 and 120 minutes also showed no observable differences between the samples exposed at 15 and 30 minute intervals. Although these observed temperature limits differ from the literature values, the trend of HDPE having a higher temperature than LDPE is consistent with the reference literature. Experimental observations indicate that the HDPE softens at elevated temperatures, but will retain its shape upon cooling. In SWDF storage practices, this might indicate some distortion of the waste container, but catastrophic failure of the liner due to elevated temperatures (<185{degrees}C) is not anticipated.« less

Factors that influence effective perioperative temperature management by anesthesiologists: a qualitative study using the Theoretical Domains Framework.

PubMed

Boet, Sylvain; Patey, Andrea M; Baron, Justine S; Mohamed, Karim; Pigford, Ashlee-Ann E; Bryson, Gregory L; Brehaut, Jamie C; Grimshaw, Jeremy M

2017-06-01

Inadvertent perioperative hypothermia (IPH) is associated with a range of adverse outcomes. Safe and effective warming techniques exist to prevent IPH; however, IPH remains common. This study aimed to identify factors that anesthesiologists perceive may influence temperature management during the perioperative period. After Research Ethics Board approval, semi-structured interviews were conducted with staff anesthesiologists at a Canadian academic hospital. An interview guide based on the Theoretical Domains Framework (TDF) was used to capture 14 theoretical domains that may influence temperature management. The interview transcripts were coded using direct content analysis to generate specific beliefs and to identify relevant TDF domains perceived to influence temperature management behaviour. Data saturation was achieved after 15 interviews. The following nine theoretical domains were identified as relevant to designing an intervention for practices in perioperative temperature management: knowledge, beliefs about capabilities, beliefs about consequences, reinforcement, memory/attention/decision-making, environmental context and resources, social/professional role/identity, social influences, and behavioural regulation. Potential target areas to improve temperature management practices include interventions that address information needs about individual temperature management behaviour as well as patient outcome (feedback), increasing awareness of possible temperature management strategies and guidelines, and a range of equipment and surgical team dynamics that influence temperature management. This study identified several potential target areas for future interventions from nine of the TDF behavioural domains that anesthesiologists perceive to drive their temperature management practices. Future interventions that aim to close the evidence-practice gap in perioperative temperature management may include these targets.

Downwell pump reliability: Geothermal experience update: Final report

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

Ellis, P.F.

1988-01-01

Geothermal resources with temperatures between 250/sup 0/ and 360/sup 0/F (121/sup 0/C and 182/sup 0/C) are prime candidates for binary-cycle power generation, and constitute about 80% of the power-capable resources in the United States. The successful exploitation of these resources requires reliable high-capacity downwell brine production pumps, but earlier experience showed that high-capacity, high-temperature geothermal production pumps had many problems which resulted in a mean time-to-failure (MTTF) of less than 1000 h. However, steady progress has been made since 1981, and a large body of experience has been acquired by three geothermal binary plants. This survey of high-temperature geothermal downwellmore » pump users and manufacturers updates a prior survey (AP-3572) completed in early 1983. This survey traces the development of lineshaft pump technology from the late 1970s to the present (mid-1987), detailing the advances in design, materials selection, and operating practices. Case histories of 72 lineshaft pumps installed at three geothermal binary plants since late 1981 are documented, including some detailed cause of failure reports. In the recent past, pump lives in excess of 7000 h have become common, but a high continuing rate of premature failures resulted in a mean time-to-failure (MTTF) of about 5000 h. Based on recent advances which appear likely to eliminate most premature failures, the estimated near-term MTTF will be on the order of 8000 h. The survey found almost no development of high-temperature geothermal electric submersible pumps (ESP's) or close-coupled downwell hydraulic turbopumps, and concluded that considerable development and demonstration will be needed before these technologies are able to compete with existing high-temperature geothermal lineshaft pump technology. 36 refs., 10 figs., 25 tabs.« less

High-density genetic map and identification of QTLs for responses to temperature and salinity stresses in the model brown alga Ectocarpus

PubMed Central

Avia, Komlan; Coelho, Susana M.; Montecinos, Gabriel J.; Cormier, Alexandre; Lerck, Fiona; Mauger, Stéphane; Faugeron, Sylvain; Valero, Myriam; Cock, J. Mark; Boudry, Pierre

2017-01-01

Deciphering the genetic architecture of adaptation of brown algae to environmental stresses such as temperature and salinity is of evolutionary as well as of practical interest. The filamentous brown alga Ectocarpus sp. is a model for the brown algae and its genome has been sequenced. As sessile organisms, brown algae need to be capable of resisting the various abiotic stressors that act in the intertidal zone (e.g. osmotic pressure, temperature, salinity, UV radiation) and previous studies have shown that an important proportion of the expressed genes is regulated in response to hyposaline, hypersaline or oxidative stress conditions. Using the double digest RAD sequencing method, we constructed a dense genetic map with 3,588 SNP markers and identified 39 QTLs for growth-related traits and their plasticity under different temperature and salinity conditions (tolerance to high temperature and low salinity). GO enrichment tests within QTL intervals highlighted membrane transport processes such as ion transporters. Our study represents a significant step towards deciphering the genetic basis of adaptation of Ectocarpus sp. to stress conditions and provides a substantial resource to the increasing list of tools generated for the species. PMID:28256542

Athermal design and analysis of glass-plastic hybrid lens

NASA Astrophysics Data System (ADS)

Yang, Jian; Cen, Zhaofeng; Li, Xiaotong

2018-01-01

With the rapid development of security market, the glass-plastic hybrid lens has gradually become a choice for the special requirements like high imaging quality in a wide temperature range and low cost. The reduction of spherical aberration is achieved by using aspherical surface instead of increasing the number of lenses. Obviously, plastic aspherical lens plays a great role in the cost reduction. However, the hybrid lens has a priority issue, which is the large thermal coefficient of expansion of plastic, causing focus shift and seriously affecting the imaging quality, so the hybrid lens is highly sensitive to the change of temperature. To ensure the system operates normally in a wide temperature range, it is necessary to eliminate the influence of temperature on the hybrid lens system. A practical design method named the Athermal Material Map is summarized and verified by an athermal design example according to the design index. It includes the distribution of optical power and selection of glass or plastic. The design result shows that the optical system has excellent imaging quality at a wide temperature range from -20 ° to 70 °. The method of athermal design in this paper has generality which could apply to optical system with plastic aspherical surface.

Structure and tribological properties of composite materials based on Al-Cu-Fe formed at high pressure

NASA Astrophysics Data System (ADS)

Golovkova, E. A.; Ekimov, E. A.; Ivanov, A. S.; Kruglov, V. S.; Pal', A. F.; Ryabinkin, A. N.; Serov, A. O.; Starostin, A. N.; Tsetlin, M. B.

2017-11-01

The use of high pressure ( 8 GPa) in the formation of composite quasi-crystalline materials from powders made it possible to create practically poreless samples with a density close to the maximum known for this type of quasi-crystals. For samples with a nickel binder, sintered at a temperature of 550°C, a very low coefficient of friction was obtained, which retain its value during the testing.

Evaluation of realistic layouts for next generation on-scalp MEG: spatial information density maps.

PubMed

Riaz, Bushra; Pfeiffer, Christoph; Schneiderman, Justin F

2017-08-01

While commercial magnetoencephalography (MEG) systems are the functional neuroimaging state-of-the-art in terms of spatio-temporal resolution, MEG sensors have not changed significantly since the 1990s. Interest in newer sensors that operate at less extreme temperatures, e.g., high critical temperature (high-T c ) SQUIDs, optically-pumped magnetometers, etc., is growing because they enable significant reductions in head-to-sensor standoff (on-scalp MEG). Various metrics quantify the advantages of on-scalp MEG, but a single straightforward one is lacking. Previous works have furthermore been limited to arbitrary and/or unrealistic sensor layouts. We introduce spatial information density (SID) maps for quantitative and qualitative evaluations of sensor arrays. SID-maps present the spatial distribution of information a sensor array extracts from a source space while accounting for relevant source and sensor parameters. We use it in a systematic comparison of three practical on-scalp MEG sensor array layouts (based on high-T c SQUIDs) and the standard Elekta Neuromag TRIUX magnetometer array. Results strengthen the case for on-scalp and specifically high-T c SQUID-based MEG while providing a path for the practical design of future MEG systems. SID-maps are furthermore general to arbitrary magnetic sensor technologies and source spaces and can thus be used for design and evaluation of sensor arrays for magnetocardiography, magnetic particle imaging, etc.

Locating illicit connections in storm water sewers using fiber-optic distributed temperature sensing.

PubMed

Hoes, O A C; Schilperoort, R P S; Luxemburg, W M J; Clemens, F H L R; van de Giesen, N C

2009-12-01

A newly developed technique using distributed temperature sensing (DTS) has been developed to find illicit household sewage connections to storm water systems in the Netherlands. DTS allows for the accurate measurement of temperature along a fiber-optic cable, with high spatial (2m) and temporal (30s) resolution. We inserted a fiber-optic cable of 1300m in two storm water drains. At certain locations, significant temperature differences with an intermittent character were measured, indicating inflow of water that was not storm water. In all cases, we found that foul water from households or companies entered the storm water system through an illicit sewage connection. The method of using temperature differences for illicit connection detection in storm water networks is discussed. The technique of using fiber-optic cables for distributed temperature sensing is explained in detail. The DTS method is a reliable, inexpensive and practically feasible method to detect illicit connections to storm water systems, which does not require access to private property.

Parametric analysis and temperature effect of deployable hinged shells using shape memory polymers

NASA Astrophysics Data System (ADS)

Tao, Ran; Yang, Qing-Sheng; He, Xiao-Qiao; Liew, Kim-Meow

2016-11-01

Shape memory polymers (SMPs) are a class of intelligent materials, which are defined by their capacity to store a temporary shape and recover an original shape. In this work, the shape memory effect of SMP deployable hinged shell is simulated by using compiled user defined material subroutine (UMAT) subroutine of ABAQUS. Variations of bending moment and strain energy of the hinged shells with different temperatures and structural parameters in the loading process are given. The effects of the parameters and temperature on the nonlinear deformation process are emphasized. The entire thermodynamic cycle of SMP deployable hinged shell includes loading at high temperature, load carrying with cooling, unloading at low temperature and recovering the original shape with heating. The results show that the complicated thermo-mechanical deformation and shape memory effect of SMP deployable hinge are influenced by the structural parameters and temperature. The design ability of SMP smart hinged structures in practical application is prospected.

Temperature estimation from molecular nitrogen UV spectra in atmospheric pressure plasmas

NASA Astrophysics Data System (ADS)

Pepper, Keenan; Kim, Yongho; Kim, Jihun

2008-11-01

Atmospheric pressure plasmas have many potential applications to fuel processing, surface treatment, and manipulation of chemical reactions. These plasmas are often non-thermal, which means different species are not in equilibrium and have different effective temperatures. This is critical for many applications because it allows high concentrations of reactive species to be produced without using a prohibitive amount of power. In the present work, numerical software was developed to estimate the vibrational and rotational temperatures (Tvib and Trot) of N2 molecules from their ultraviolet emission spectra. The electron temperature Te can also be estimated by comparing the N2 spectrum to that of the N2^+ molecular ion. This technique is applied to several plasma sources including audio frequency, RF, and microwave devices. The results are presented and their implications for practical applications are discussed.

Room-temperature ferromagnetic Cr-doped Ge/GeOx core-shell nanowires.

PubMed

Katkar, Amar S; Gupta, Shobhnath P; Seikh, Md Motin; Chen, Lih-Juann; Walke, Pravin S

2018-06-08

The Cr-doped tunable thickness core-shell Ge/GeO x nanowires (NWs) were synthesized and characterized using x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and magnetization studies. The shell thickness increases with the increase in synthesis temperature. The presence of metallic Cr and Cr 3+ in core-shell structure was confirmed from XPS study. The magnetic property is highly sensitive to the core-shell thickness and intriguing room temperature ferromagnetism is realized only in core-shell NWs. The magnetization decreases with an increase in shell thickness and practically ceases to exist when there is no core. These NWs show remarkably high Curie temperature (T C  > 300 K) with the dominating values of its magnetic remanence (M R ) and coercivity (H C ) compared to germanium dilute magnetic semiconductor nanomaterials. We believe that our finding on these Cr-doped Ge/GeO X core-shell NWs has the potential to be used as a hard magnet for future spintronic devices, owing to their higher characteristic values of ferromagnetic ordering.

Tribological characteristics of sputtered Au/Cr films on alumina substrates at elevated temperatures

NASA Technical Reports Server (NTRS)

Benoy, P. A.; Dellacorte, C.

1993-01-01

Research to evaluate the tribological properties of alumina pins sliding against thin sputtered gold films deposited on alumina disk substrates is described. A 250 A thick chromium interlayer was first deposited onto the alumina test disks to enhance adhesion and high temperature wetting of the gold films. The Au/Cr films were tribotested in pure sliding in a pin-on-disk tribometer under a 4.9 N load at 1m/s. The test atmosphere was room air at temperatures of 25, 500, and 800 C and the test duration varied from 60 to 540 min. The use of the Au/Cr films reduced friction by about a factor of two compared to the unlubricated alumina sliding couple. The coatings prevented wear of the alumina substrate disks and reduced pin wear by one to two orders of magnitude. In addition, wear lives in excess of 200,000 sliding passes (9 hr) were observed during sliding at 800 C. The results suggest that these films show promise for the practical lubrication of many high temperature sliding components.

Active magnetic regenerator

DOEpatents

Barclay, J.A.; Steyert, W.A.

1981-01-27

An apparatus and method for refrigeration are disclosed which provides efficient refrigeration over temperature ranges in excess of 20/sup 0/C and which requires no maintenance and is, therefore, usable on an unmanned satellite. The apparatus comprises a superconducting magnet which may be solenoidal. A piston comprising a substance such as a rare earth substance which is maintained near its Curie temperature reciprocates through the bore of the solenoidal magnet. A magnetic drive rod is connected to the piston and appropriate heat sinks are connected thereto. The piston is driven by a suitable mechanical drive such as an electric motor and cam. In practicing the invention, the body of the piston is magnetized and demagnetized as it moves through the magnetic field of the solenoid to approximate any of the following cycles or a condition thereof as well as, potentially, other cycles: Brayton, Carnot, Ericsson, and Stirling. Advantages of the present invention include: that refrigeration can be accomplished over at least a 20/sup 0/C scale at superconducting temperatures as well as at more conventional temperatures; very high efficiency, high reliability, and small size. (LCL)

Room-temperature ferromagnetic Cr-doped Ge/GeOx core–shell nanowires

NASA Astrophysics Data System (ADS)

Katkar, Amar S.; Gupta, Shobhnath P.; Motin Seikh, Md; Chen, Lih-Juann; Walke, Pravin S.

2018-06-01

The Cr-doped tunable thickness core–shell Ge/GeOx nanowires (NWs) were synthesized and characterized using x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy and magnetization studies. The shell thickness increases with the increase in synthesis temperature. The presence of metallic Cr and Cr3+ in core–shell structure was confirmed from XPS study. The magnetic property is highly sensitive to the core–shell thickness and intriguing room temperature ferromagnetism is realized only in core–shell NWs. The magnetization decreases with an increase in shell thickness and practically ceases to exist when there is no core. These NWs show remarkably high Curie temperature (TC > 300 K) with the dominating values of its magnetic remanence (MR) and coercivity (HC) compared to germanium dilute magnetic semiconductor nanomaterials. We believe that our finding on these Cr-doped Ge/GeOX core–shell NWs has the potential to be used as a hard magnet for future spintronic devices, owing to their higher characteristic values of ferromagnetic ordering.

Exploring high dimensional free energy landscapes: Temperature accelerated sliced sampling

NASA Astrophysics Data System (ADS)

Awasthi, Shalini; Nair, Nisanth N.

2017-03-01

Biased sampling of collective variables is widely used to accelerate rare events in molecular simulations and to explore free energy surfaces. However, computational efficiency of these methods decreases with increasing number of collective variables, which severely limits the predictive power of the enhanced sampling approaches. Here we propose a method called Temperature Accelerated Sliced Sampling (TASS) that combines temperature accelerated molecular dynamics with umbrella sampling and metadynamics to sample the collective variable space in an efficient manner. The presented method can sample a large number of collective variables and is advantageous for controlled exploration of broad and unbound free energy basins. TASS is also shown to achieve quick free energy convergence and is practically usable with ab initio molecular dynamics techniques.

Effects of Carbonization Temperature on Nature of Nanostructured Electrode Materials Derived from Fe-MOF for Supercapacitors

NASA Astrophysics Data System (ADS)

Sui, Yanwei; Zhang, Dongling; Han, Yongpeng; Sun, Zhi; Qi, Jiqiu; Wei, Fuxiang; He, Yezeng; Meng, Qingkun

2018-05-01

This work successfully demonstrates various temperature carbonization of iron based metal organic framework to derive electrode materials for supercapacitors. Furthermore, impacts of calcined temperatures on the nature of as-prepared products are reported, and samples obtained at 300, 400, 500, 600 and 700 °C were investigated respectively. The products reveals excellent electrochemical performance. Carbonized at 600 °C, the composite materials display the highest specific capacitance of 972 F/g at a current density of 1 A/g. Carbonized at 500 °C, the capacitance retention of materials reach up to 93%. The high specific capacitance and excellent cyclic stability of the developed materials would exhibit nice prospect for the practical utilization of electrode materials.

Study of ultrasonic thermometry based on ultrasonic time-of-flight measurement

NASA Astrophysics Data System (ADS)

Jia, Ruixi; Xiong, Qingyu; Wang, Lijie; Wang, Kai; Shen, Xuehua; Liang, Shan; Shi, Xin

2016-03-01

Ultrasonic thermometry is a kind of acoustic pyrometry and it has been evolving as a new temperature measurement technology for various environment. However, the accurate measurement of the ultrasonic time-of-flight is the key for ultrasonic thermometry. In this paper, we study the ultrasonic thermometry technique based on ultrasonic time-of-flight measurement with a pair of ultrasonic transducers for transmitting and receiving signal. The ultrasonic transducers are installed in a single path which ultrasonic travels. In order to validate the performance of ultrasonic thermometry, we make a contrast about the absolute error between the measured temperature value and the practical one. With and without heater source, the experimental results indicate ultrasonic thermometry has high precision of temperature measurement.

Elimination of Speckle and Target Orientation Requirements in Millimeter-Wave Active Imaging by Modulated Multimode Mixing Illumination

DTIC Science & Technology

2012-12-01

arrays. 3. Thermal and Active Illumination Power It is useful to note that a passive imager with 10 GHz band - width and a diffraction-limited 100 × 100...practical by the high brightness temperatures (1014–1018 K) that can be attained with narrow- band electronic illuminators. (4) Because of this high ...091604 (2012). 21. K. B. Cooper, R. J. Denglera, N. Llombartb, A. Talukdera, A. V. Panangadana, C. S . Peaya, I. Mehdia, and P. H. Siegel, “Fast, high

Wurtzite Spin-Lasers

NASA Astrophysics Data System (ADS)

Xu, Gaofeng; Faria Junior, Paulo E.; Sipahi, Guilherme M.; Zutic, Igor

Lasers in which spin-polarized carriers are injected provide paths to different practical room temperature spintronic devices, not limited to magnetoresistive effects. While theoretical studies of such spin-lasers have focused on zinc-blende semiconductors as their active regions, the first electrically injected carriers at room temperature were recently demonstrated in GaN-based wurtzite semiconductors, recognized also for the key role as highly-efficient light emitting diodes. By focusing on a wurtzite quantum well-based spin-laser, we use accurate electronic structure calculations to develop a microscopic description for its lasing properties. We discuss important differences between wurtzite and zinc-blende spin-lasers.

Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

2017-01-01

A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.

syn-Selective crotylation of aldehydes using bismuth-crotyl bromide-(1-butyl-3-methylimidazolium bromide) combination: some synthetic applications.

PubMed

Goswami, Dibakar; Koli, Mrunesh R; Chatterjee, Sucheta; Chattopadhyay, Subrata; Sharma, Anubha

2017-05-03

The Bi-[bmim][Br] combination has been found to offer high syn-selectivity in the crotylation of aldehydes with crotyl bromide using practically stoichiometric amounts of the reagents. The room temperature ionic liquid (RTIL), [bmim][Br], activated Bi metal in the presence of oxygen to produce crotylbismuthdibromide, which reacted with the aldehydes at room temperature. The major anti-syn diastereomeric product obtained from the crotylation of (R)-cyclohexylideneglyceraldehyde was utilized for the synthesis of dictyostatin and cryptophycin segments, and (+)-cis-aerangis lactone, using standard synthetic protocols.

Operational methods of thermodynamics. Volume 1 - Temperature measurement

NASA Astrophysics Data System (ADS)

Eder, F. X.

The principles of thermometry are examined, taking into account the concept of temperature, the Kelvin scale, the statistical theory of heat, negative absolute temperatures, the thermodynamic temperature scale, the thermodynamic temperature scale below 1 K, noise thermometry, temperature scales based on black-body radiation, acoustical thermometry, and the International Practical Temperature Scale 1968. Aspects of practical temperature measurement are discussed, giving attention to thermometers based on the expansion of a gas or a liquid, instruments utilizing the relative thermal expansion of two different metals, devices measuring the vapor pressure of a liquid, thermocouples, resistance thermometers, radiation pyrometers of various types, instruments utilizing the temperature dependence of a number of material characteristics, devices for temperature control, thermometer calibration, and aspects of thermometer installation and inertia. A description is presented of the approaches employed for the measurement of low temperatures.

Fecal Immunochemical Test (FIT) for Colon Cancer Screening: Variable Performance with Ambient Temperature

PubMed Central

Doubeni, Chyke A.; Jensen, Christopher D.; Fedewa, Stacey A.; Quinn, Virginia P.; Zauber, Ann G.; Schottinger, Joanne E.; Corley, Douglas A.; Levin, Theodore R.

2017-01-01

Introduction Fecal immunochemical tests (FITs) are widely used in colorectal cancer (CRC) screening, but hemoglobin degradation, due to exposure of the collected sample to high temperatures, could reduce test sensitivity. We examined the relation of ambient temperature exposure with FIT positivity rate and sensitivity. Methods This was a retrospective cohort study of patients 50 to 75 years in Kaiser Permanente Northern California’s CRC screening program, which began mailing FIT kits annually to screen-eligible members in 2007. Primary outcomes were FIT positivity rate and sensitivity to detect CRC. Predictors were month, season, and daily ambient temperatures of test result dates based on US National Oceanic and Atmospheric Administration data. Results Patients (n =472,542) completed 1,141,162 FITs. Weekly test positivity rate ranged from 2.6% to 8.0% (median, 4.4%) and varied significantly by month (June/July vs December/January rate ratio [RR] =0.79, 95% confidence interval [CI], 0.76 to 0.83) and season. FIT sensitivity was lower in June/July (74.5%; 95% CI, 72.5 to 76.6) than January/December (78.9%; 95% CI, 77.0 to 80.7). Conclusions FITs completed during high ambient temperatures had lower positivity rates and lower sensitivity. Changing kit design, specimen transportation practices, or avoiding periods of high ambient temperatures may help optimize FIT performance, but may also increase testing complexity and reduce patient adherence, requiring careful study. PMID:28076249

Outstanding compressive creep strength in Cr/Ir-codoped (Mo0.85Nb0.15)Si2 crystals with the unique cross-lamellar microstructure.

PubMed

Hagihara, Koji; Ikenishi, Takaaki; Araki, Haruka; Nakano, Takayoshi

2017-06-21

A (Mo 0.85 Nb 0.15 )Si 2 crystal with an oriented, lamellar, C40/C11 b two-phase microstructure is a promising ultrahigh-temperature (UHT) structural material, but its low room-temperature fracture toughness and low high-temperature strength prevent its practical application. As a possibility to overcome these problems, we first found a development of unique "cross-lamellar microstructure", by the cooping of Cr and Ir. The cross-lamellar microstructure consists of a rod-like C11 b -phase grains that extend along a direction perpendicular to the lamellar interface in addition to the C40/C11 b fine lamellae. In this study, the effectiveness of the cross-lamellar microstructure for improving the high-temperature creep deformation property, being the most essential for UHT materials, was examined by using the oriented crystals. The creep rate significantly reduced along a loading orientation parallel to the lamellar interface. Furthermore, the degradation in creep strength for other loading orientation that is not parallel to the lamellar interface, which has been a serious problem up to now, was also suppressed. The results demonstrated that the simultaneous improvement of high-temperature creep strength and room temperature fracture toughness can be first accomplished by the development of unique cross-lamellar microstructure, which opens a potential avenue for the development of novel UHT materials as alternatives to existing Ni-based superalloys.

Study on cold head structure of a 300 Hz thermoacoustically driven pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Yu, G. Y.; Wang, X. T.; Dai, W.; Luo, E. C.

2012-04-01

High reliability, compact size and potentially high thermal efficiency make the high frequency thermoacoustically-driven pulse tube cryocooler quite promising for space use. With continuous efforts, the lowest temperature and the thermal efficiency of the coupled system have been greatly improved. So far, a cold head temperature below 60 K has been achieved on such kind of cryocooler with the operation frequency of around 300 Hz. To further improve the thermal efficiency and expedite its practical application, this work focuses on studying the influence of cold head structure on the system performance. Substantial numerical simulations were firstly carried out, which revealed that the cold head structure would greatly influence the cooling power and the thermal efficiency. To validate the predictions, a lot of experiments have been done. The experiments and calculations are in reasonable agreement. With 500 W heating power input into the engine, a no-load temperature of 63 K and a cooling power of 1.16 W at 80 K have been obtained with parallel-plate cold head, indicating encouraging improvement of the thermal efficiency.

Superplasticity in a lean Fe-Mn-Al steel.

PubMed

Han, Jeongho; Kang, Seok-Hyeon; Lee, Seung-Joon; Kawasaki, Megumi; Lee, Han-Joo; Ponge, Dirk; Raabe, Dierk; Lee, Young-Kook

2017-09-29

Superplastic alloys exhibit extremely high ductility (>300%) without cracks when tensile-strained at temperatures above half of their melting point. Superplasticity, which resembles the flow behavior of honey, is caused by grain boundary sliding in metals. Although several non-ferrous and ferrous superplastic alloys are reported, their practical applications are limited due to high material cost, low strength after forming, high deformation temperature, and complicated fabrication process. Here we introduce a new compositionally lean (Fe-6.6Mn-2.3Al, wt.%) superplastic medium Mn steel that resolves these limitations. The medium Mn steel is characterized by ultrafine grains, low material costs, simple fabrication, i.e., conventional hot and cold rolling, low deformation temperature (ca. 650 °C) and superior ductility above 1300% at 850 °C. We suggest that this ultrafine-grained medium Mn steel may accelerate the commercialization of superplastic ferrous alloys.Research in new alloy compositions and treatments may allow the increased strength of mass-produced, intricately shaped parts. Here authors introduce a superplastic medium manganese steel which has an inexpensive lean chemical composition and which is suited for conventional manufacturing processes.

Fuel-rich catalytic combustion: A fuel processor for high-speed propulsion

NASA Technical Reports Server (NTRS)

Brabbs, Theodore A.; Rollbuhler, R. James; Lezberg, Erwin A.

1990-01-01

Fuel-rich catalytic combustion of Jet-A fuel was studied over the equivalence ratio range 4.7 to 7.8, which yielded combustion temperatures of 1250 to 1060 K. The process was soot-free and the gaseous products were similar to those obtained in the iso-octane study. A carbon atom balance across the catalyst bed calculated for the gaseous products accounted for about 70 to 90 percent of the fuel carbon; the balance was condensed as a liquid in the cold trap. It was shown that 52 to 77 percent of the fuel carbon was C1, C2, and C3 molecules. The viability of using fuel-rich catalytic combustion as a technique for preheating a practical fuel to very high temperatures was demonstrated. Preliminary results from the scaled up version of the catalytic combustor produced a high-temperature fuel containing large amounts of hydrogen and carbon monoxide. The balance of the fuel was completely vaporized and in various stages of pyrolysis and oxidation. Visual observations indicate that there was no soot present.

Kinetic Behavior and Microstructure of Pearlite Isothermal Transformation Under High Undercooling

NASA Astrophysics Data System (ADS)

Liang, Yu; Xu, Pingwei; Xiang, Song; Liang, Yilong; Xiong, Hu; Li, Jing

2018-06-01

The kinetic behavior of highly undercooled austenite and its effects on the microstructural evolution and mechanical properties of high-carbon steel are studied. The undercooling degree is increased through a temporary undercooling treatment at the bainite transformation temperature of 380 °C to 450 °C before the pearlite isothermal transformation at 500 °C to 620 °C. The transformation kinetics reveals an increased nose temperature and a rightward shift of the transformation curve under high undercooling conditions. In addition, the undercooling treatment leads to an increased driving force during pearlite transformation, which is responsible for the refined hierarchical structures of pearlite. As a result, a 20 to 40 pct size reduction is achieved for pearlite colonies and lamellae. Such refinement is in turn attributed to an 26 pct increase in reduction in area. This work provides both a new understanding of high-performance fully pearlitic steels for practical applications and new perspectives for potential technological applications in drawing processes for hypoeutectoid steels.

Influence of thiourea application on some physiological and molecular criteria of sunflower (Helianthus annuus L.) plants under conditions of heat stress.

PubMed

Akladious, Samia Ageeb

2014-05-01

High temperature is a major factor limiting the growth of plant species during summer. Understanding the mechanisms of plant tolerance to high temperature would help in developing effective management practices and heat-tolerant cultivars through breeding or biotechnology. The present investigation was carried out to study the role of thiourea in enhancing the tolerance of sunflower plants to heat stress. Sunflower plants were subjected to temperature stress by exposing plants to 35 or 45 °C for 12 h. Two levels of thiourea (10 and 20 mM) were applied before sowing (seed treatment). The results indicated that the plants exposed to temperature stress exhibited a significant decline in growth parameters, chlorophylls, relative leaf water content, oil content, leaf nutrient status, and nitrate reductase activity. Treatment with thiourea, especially when applied at 10 mM, improved the above parameters and induced non-enzymatic and enzymatic antioxidants responsible for antioxidation. SDS-PAGE of protein revealed that high-temperature treatments alone or in combination with thiourea were associated with the disappearance of some bands or the appearance of unique ones. The result of RAPD analysis using five primers showed variable qualitative and quantitative changes. These findings confirm the effectiveness of applying thiourea on alleviating heat injuries in sunflower plants.

Modeling Allometric Relationships in Leaves of Young Rapeseed (Brassica napus L.) Grown at Different Temperature Treatments

PubMed Central

Tian, Tian; Wu, Lingtong; Henke, Michael; Ali, Basharat; Zhou, Weijun; Buck-Sorlin, Gerhard

2017-01-01

Functional–structural plant modeling (FSPM) is a fast and dynamic method to predict plant growth under varying environmental conditions. Temperature is a primary factor affecting the rate of plant development. In the present study, we used three different temperature treatments (10/14°C, 18/22°C, and 26/30°C) to test the effect of temperature on growth and development of rapeseed (Brassica napus L.) seedlings. Plants were sampled at regular intervals (every 3 days) to obtain growth data during the length of the experiment (1 month in total). Total leaf dry mass, leaf area, leaf mass per area (LMA), width-length ratio, and the ratio of petiole length to leaf blade length (PBR), were determined and statistically analyzed, and contributed to a morphometric database. LMA under high temperature was significantly smaller than LMA under medium and low temperature, while leaves at high temperature were significantly broader. An FSPM of rapeseed seedlings featuring a growth function used for leaf extension and biomass accumulation was implemented by combining measurement with literature data. The model delivered new insights into growth and development dynamics of winter oilseed rape seedlings. The present version of the model mainly focuses on the growth of plant leaves. However, future extensions of the model could be used in practice to better predict plant growth in spring and potential cold damage of the crop. PMID:28377775

Experimental aspects of buoyancy correction in measuring reliable high-pressure excess adsorption isotherms using the gravimetric method

NASA Astrophysics Data System (ADS)

Nguyen, Huong Giang T.; Horn, Jarod C.; Thommes, Matthias; van Zee, Roger D.; Espinal, Laura

2017-12-01

Addressing reproducibility issues in adsorption measurements is critical to accelerating the path to discovery of new industrial adsorbents and to understanding adsorption processes. A National Institute of Standards and Technology Reference Material, RM 8852 (ammonium ZSM-5 zeolite), and two gravimetric instruments with asymmetric two-beam balances were used to measure high-pressure adsorption isotherms. This work demonstrates how common approaches to buoyancy correction, a key factor in obtaining the mass change due to surface excess gas uptake from the apparent mass change, can impact the adsorption isotherm data. Three different approaches to buoyancy correction were investigated and applied to the subcritical CO2 and supercritical N2 adsorption isotherms at 293 K. It was observed that measuring a collective volume for all balance components for the buoyancy correction (helium method) introduces an inherent bias in temperature partition when there is a temperature gradient (i.e. analysis temperature is not equal to instrument air bath temperature). We demonstrate that a blank subtraction is effective in mitigating the biases associated with temperature partitioning, instrument calibration, and the determined volumes of the balance components. In general, the manual and subtraction methods allow for better treatment of the temperature gradient during buoyancy correction. From the study, best practices specific to asymmetric two-beam balances and more general recommendations for measuring isotherms far from critical temperatures using gravimetric instruments are offered.

Thermal effects of white light illumination during microsurgery: clinical pilot study on the application safety of surgical microscopes.

PubMed

Hibst, Raimund; Saal, David; Russ, Detlef; Kunzi-Rapp, Karin; Kienle, Alwin; Stock, Karl

2010-01-01

Modern operating microscopes offer high power illumination to ensure optimal visualization, but can also cause thermal damage. The aim of our study is to quantify the thermal effects in vivo and discuss conditions for safe use. In a pilot study on volunteers, we measured the temperature at the skin surface during microscope illumination, including the influence of anaesthesia and the effects of staining, draping, or moistening of the skin. Irradiation within the limit given by safety regulations (200 mW/cm(2)) results in skin surface temperature of 43 degrees C. Higher intensities (forearm 335 mW/cm(2), back 250 mW/cm(2)) are tolerated, resulting in reversible hyperaemia. At a very high illumination intensity (750 mW/cm(2)), pain occurs within 30 s at temperatures of 46 degrees C+/-1 degrees C (hand and forearm), and 43 degrees C+/-2 degrees C (back), respectively. Anaesthesia has no distinct effect on the temperature, whereas staining and drapes result in much higher temperatures (>100 degrees C). Moistening at practicable flow rates can reduce temperature efficiently when combined with a light absorbing and water absorbent drape. In conclusion, surgeons must be aware that surgical microscope illumination without protective means can cause skin temperatures to rise much above pain threshold, which in our study serves as a (conservative) benchmark for potential damage.

Thermal effects of white light illumination during microsurgery: clinical pilot study on the application safety of surgical microscopes

NASA Astrophysics Data System (ADS)

Hibst, Raimund; Saal, David; Russ, Detlef; Kunzi-Rapp, Karin; Kienle, Alwin; Stock, Karl

2010-07-01

Modern operating microscopes offer high power illumination to ensure optimal visualization, but can also cause thermal damage. The aim of our study is to quantify the thermal effects in vivo and discuss conditions for safe use. In a pilot study on volunteers, we measured the temperature at the skin surface during microscope illumination, including the influence of anaesthesia and the effects of staining, draping, or moistening of the skin. Irradiation within the limit given by safety regulations (200 mW/cm2) results in skin surface temperature of 43 °C. Higher intensities (forearm 335 mW/cm2, back 250 mW/cm2) are tolerated, resulting in reversible hyperaemia. At a very high illumination intensity (750 mW/cm2), pain occurs within 30 s at temperatures of 46 °C+/-1 °C (hand and forearm), and 43 °C+/-2 °C (back), respectively. Anaesthesia has no distinct effect on the temperature, whereas staining and drapes result in much higher temperatures (>100 °C). Moistening at practicable flow rates can reduce temperature efficiently when combined with a light absorbing and water absorbent drape. In conclusion, surgeons must be aware that surgical microscope illumination without protective means can cause skin temperatures to rise much above pain threshold, which in our study serves as a (conservative) benchmark for potential damage.

High-performance graphene/sulphur electrodes for flexible Li-ion batteries using the low-temperature spraying method

NASA Astrophysics Data System (ADS)

Kumar, Pushpendra; Wu, Feng-Yu; Hu, Lung-Hao; Ali Abbas, Syed; Ming, Jun; Lin, Chia-Nan; Fang, Jason; Chu, Chih-Wei; Li, Lain-Jong

2015-04-01

Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes.Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (~70% capacity retention after 250 cycles), good coulombic efficiency (~98%) and high capacity (~1500 mA h g-1) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00885a

Effectiveness of a web-based education program to improve vaccine storage conditions in primary care (Keep Cool): study protocol for a randomized controlled trial.

PubMed

Thielmann, Anika; Viehmann, Anja; Weltermann, Birgitta M

2015-07-14

Immunization programs are among the most effective public health strategies worldwide. Adequate vaccine storage is a prerequisite to assure the vaccines' effectiveness and safety. In a questionnaire survey among a random sample of German primary care physicians, we discovered vaccine storage deficits: 16% of physicians had experience with cold chain breaches either as an error or near error, 49 % did not keep a temperature log, and 21 % did not use a separate refrigerator for vaccine storage. In a recent feasibility study of 21 practice refrigerators, we showed that these were outside the target range 10.2% of the total time with some single refrigerators being outside the target range as much as 66.3% of the time. These cooling-chain deficits are consistent with the international medical literature, yet an effective, easy to disseminate, practice-centered intervention to improve storage conditions is lacking. This randomized intervention trial will be conducted in a random sample of primary care practices. Based on continuous temperature recordings over 7 days, all practices with readings outside the target range for vaccine storage (+2 °C to +8 °C) will be randomly allocated to a web-based education program or a waiting list control group. The practice physicians and their teams constitute the target population. Participants will be educated about best practices in vaccine storage and will receive a manual including storage checklists and templates for temperature documentation. In all practices, temperatures of the vaccine refrigerators will be monitored continuously using a data logger with a glycol probe as a surrogate for vaccine vial temperature. The effectiveness of the web-based education program will be determined after 6 months in terms of the proportion of refrigerators with vaccine vial temperatures within the target range (+2 °C to +8 °C) during 7-day temperature logging. Secondary outcome parameters include temperature monitoring, no critically low temperatures (≤ -0.5 °C), compliance with storage recommendations, knowledge of good vaccine storage conditions, and assignment of personnel as vaccine storage manager and backup. Keep Cool will develop and evaluate a web-based education program to improve vaccine storage conditions in primary care and thereby ensure immunization safety and effectiveness. DRKS00006561 (date of registration: 20 February 2015).

Breakdown characteristics of SF6/N2 in severely non-uniform electric fields at low temperatures

NASA Astrophysics Data System (ADS)

Wang, Y.; Gao, Z. W.; Li, G. X.; Zhu, X. C.; Yu, C. L.; Liang, J. Q.; Li, L.

2018-01-01

SF6 has good electrical insulating properties, which is widely used as an insulating medium of GIS, GIL and other electrical equipment. However, the reliability of electrical equipments´ insulated gas is greatly challenged in cold areas, since SF6 more readily liquefies. To solve the problem, SF6 can be mixed with N2 to maintain the insulating properties, and reduce its liquefaction temperature. Such practice has certain application prospect. In this paper, a breakdown experimental platform was built to study the insulating property of SF6/N2 at low temperature, wherein the temperature of the platform can be adjusted. A severely non-uniform electric field was generated by a rod-plate electrode. The breakdown characteristics of SF6/N2 with different mixing proportions at low pressures and low temperatures were measured. The result showed that the mixed gas was not liquefied within the temperature range. Temperature had insignificant influence on the insulating property thereof. The result in the paper has certain guiding significance for applying SF6/N2 mixed gas in high latitude areas.

Effect of temperature on the performances and in situ polarization analysis of zinc-nickel single flow batteries

NASA Astrophysics Data System (ADS)

Cheng, Yuanhui; Zhang, Huamin; Lai, Qinzhi; Li, Xianfeng; Zheng, Qiong; Xi, Xiaoli; Ding, Cong

2014-03-01

The recently proposed high power density zinc-nickel single flow batteries (ZNBs) exhibit great potential for larger scale energy storage. The urgent needs are in the research into temperature adaptability of ZNBs before practical utilization. Furthermore, making clear their polarization distribution is essential to direct the further improvement of battery performance. Here, we focus on the trends in the polarization distribution and effect of temperature on the performance of ZNBs. The result shows that ZNBs can operate in the temperature range from 0 °C to 40 °C with acceptable energy efficiency (53%-79.1%) at 80 mA cm-2. The temperature sensitivity of coulombic efficiency and energy efficiency are 0.65% °C-1 and 0.98% °C-1 at 0 °C-20 °C, respectively. The positive polarization is much larger than the negative polarization at all studied temperatures. The charge overpotential of the positive electrode is more sensitive to temperature. These results enable us to better evaluate the application prospect of ZNBs and point a clear struggling orientation to further improve the battery performance.

Appropriate experimental ecosystem warming methods by ecosystem, objective, and practicality

Treesearch

E.L. Aronson; S.G. McNulty

2009-01-01

The temperature of the Earth is rising, and is highly likely to continue to do so for the foreseeable future. The study of the effects of sustained heating on the ecosystems of the world is necessary so that wemight predict and respond to coming changes on both large and small spatial scales. To this end, ecosystem warming studies have...

Operation and design selection of high temperature superconducting magnetic bearings

NASA Astrophysics Data System (ADS)

Werfel, F. N.; Floegel-Delor, U.; Riedel, T.; Rothfeld, R.; Wippich, D.; Goebel, B.

2004-10-01

Axial and radial high temperature superconducting (HTS) magnetic bearings are evaluated by their parameters. Journal bearings possess advantages over thrust bearings. High magnetic gradients in a multi-pole permanent magnet (PM) configuration, the surrounding melt textured YBCO stator and adequate designs are the key features for increasing the overall bearing stiffness. The gap distance between rotor and stator determines the specific forces and has a strong impact on the PM rotor design. We report on the designing, building and measuring of a 200 mm prototype 100 kg HTS bearing with an encapsulated and thermally insulated melt textured YBCO ring stator. The encapsulation requires a magnetically large-gap (4-5 mm) operation but reduces the cryogenic effort substantially. The bearing requires 3 l of LN2 for cooling down, and about 0.2 l LN2 h-1 under operation. This is a dramatic improvement of the efficiency and in the practical usage of HTS magnetic bearings.

Local structure of high-coercivity Fe-Ni-Al alloys

NASA Astrophysics Data System (ADS)

Menushenkov, A. P.; Menushenkov, V. P.; Chernikov, R. V.; Sviridova, T. A.; Grishina, O. V.; Sidorov, V. V.

2011-04-01

Results of hard magnetic Fe-Ni-Al alloys after various thermal processing local structure researches by method of EXAFS-spectroscopy with use of synchrotron radiation at temperature 77 K are presented. It is established, that during cooling a firm solution with critical speed reorganization of a local environment of nickel relative to quickly tempered sample owing to stratification of a firm solution is observed. The subsequent aging at 780°C practically restores local structure, characteristic for quickly tempered sample, keeping thus rather high coercitive force.

“Ni-Less” Cathodes for High Energy Density, Intermediate Temperature Na-NiCl 2 Batteries

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

Chang, Hee-Jung; Lu, Xiaochuan; Bonnett, Jeffery F.

Among various battery technologies being considered for stationary energy storage applications, sodium-metal halide (Na-MH) batteries have become one of the most attractive candidates because of the abundance of raw materials, long cycle life, high energy density, and superior safety. However, one of issues limiting its practical application is the relatively expensive nickel (Ni) used in the cathode. In the present work, we focus on of efforts to develop new Ni-based cathodes, and demonstrate that a much higher specific energy density of 405 Wh/kg (23% higher than state-of-the-art Na-MH batteries) can be achieved at an operating temperature of 190oC. Furthermore, 15%more » less Ni is used in the new cathode than that in conventional Na-NiCl2 batteries. Long-term cycling tests also show stable electrochemical performance for over 300 cycles with excellent capacity retention (~100%). The results in this work indicate that these advances can significantly reduce the raw material cost associated with Ni (a 31% reduction) and promote practical applications of Na-MH battery technologies in stationary energy storage systems.« less

Rheometry of polymer melts using processing machines

NASA Astrophysics Data System (ADS)

Friesenbichler, Walter; Neunhäuserer, Andreas; Duretek, Ivica

2016-08-01

The technology of slit-die rheometry came into practice in the early 1960s. This technique enables engineers to measure the pressure drop very precisely along the slit die. Furthermore, slit-die rheometry widens up the measurable shear rate range and it is possible to characterize rheological properties of complicated materials such as wall slipping PVCs and high-filled compounds like long fiber reinforced thermoplastics and PIM-Feedstocks. With the use of slit-die systems in polymer processing machines e.g., Rauwendaal extrusion rheometer, by-pass extrusion rheometer, injection molding machine rheometers, new possibilities regarding rheological characterization of thermoplastics and elastomers at processing conditions near to practice opened up. Special slit-die systems allow the examination of the pressure-dependent viscosity and the characterization of cross-linking elastomers because of melt preparation and reachable shear rates comparable to typical processing conditions. As a result of the viscous dissipation in shear and elongational flows, when performing rheological measurements for high-viscous elastomers, temperature-correction of the apparent values has to be made. This technique was refined over the last years at Montanuniversitaet. Nowadays it is possible to characterize all sorts of rheological complicated polymeric materials under process- relevant conditions with viscosity values fully temperature corrected.

Compatibility between Co-Metallized PbTe Thermoelectric Legs and an Ag-Cu-In Brazing Alloy.

PubMed

Ben-Ayoun, Dana; Sadia, Yatir; Gelbstein, Yaniv

2018-01-10

In thermoelectric (TE) generators, maximizing the efficiency of conversion of direct heat to electricity requires the reduction of any thermal and electrical contact resistances between the TE legs and the metallic contacts. This requirement is especially challenging in the development of intermediate to high-temperature TE generators. PbTe-based TE materials are known to be highly efficient up to temperatures of around 500 °C; however, only a few practical TE generators based on these materials are currently commercially available. One reason for that is the insufficient bonding techniques between the TE legs and the hot-side metallic contacts. The current research is focused on the interaction between cobalt-metallized n -type 9.104 × 10 -3 mol % PbI₂-doped PbTe TE legs and the Ag 0.32 Cu 0.43 In 0.25 brazing alloy, which is free of volatile species. Clear and fine interfaces without any noticeable formation of adverse brittle intermetallic compounds were observed following prolonged thermal treatment testing. Moreover, a reasonable electrical contact resistance of ~2.25 mΩmm² was observed upon brazing at 600 °C, highlighting the potential of such contacts while developing practical PbTe-based TE generators.

Determination of Germination Response to Temperature and Water Potential for a Wide Range of Cover Crop Species and Related Functional Groups

PubMed Central

Tribouillois, Hélène; Dürr, Carolyne; Demilly, Didier; Wagner, Marie-Hélène; Justes, Eric

2016-01-01

A wide range of species can be sown as cover crops during fallow periods to provide various ecosystem services. Plant establishment is a key stage, especially when sowing occurs in summer with high soil temperatures and low water availability. The aim of this study was to determine the response of germination to temperature and water potential for diverse cover crop species. Based on these characteristics, we developed contrasting functional groups that group species with the same germination ability, which may be useful to adapt species choice to climatic sowing conditions. Germination of 36 different species from six botanical families was measured in the laboratory at eight temperatures ranging from 4.5–43°C and at four water potentials. Final germination percentages, germination rate, cardinal temperatures, base temperature and base water potential were calculated for each species. Optimal temperatures varied from 21.3–37.2°C, maximum temperatures at which the species could germinate varied from 27.7–43.0°C and base water potentials varied from -0.1 to -2.6 MPa. Most cover crops were adapted to summer sowing with a relatively high mean optimal temperature for germination, but some Fabaceae species were more sensitive to high temperatures. Species mainly from Poaceae and Brassicaceae were the most resistant to water deficit and germinated under a low base water potential. Species were classified, independent of family, according to their ability to germinate under a range of temperatures and according to their base water potential in order to group species by functional germination groups. These groups may help in choosing the most adapted cover crop species to sow based on climatic conditions in order to favor plant establishment and the services provided by cover crops during fallow periods. Our data can also be useful as germination parameters in crop models to simulate the emergence of cover crops under different pedoclimatic conditions and crop management practices. PMID:27532825

Optimising the efficiency of pulsed diode pumped Yb:YAG laser amplifiers for ns pulse generation.

PubMed

Ertel, K; Banerjee, S; Mason, P D; Phillips, P J; Siebold, M; Hernandez-Gomez, C; Collier, J C

2011-12-19

We present a numerical model of a pulsed, diode-pumped Yb:YAG laser amplifier for the generation of high energy ns-pulses. This model is used to explore how optical-to-optical efficiency depends on factors such as pump duration, pump spectrum, pump intensity, doping concentration, and operating temperature. We put special emphasis on finding ways to achieve high efficiency within the practical limitations imposed by real-world laser systems, such as limited pump brightness and limited damage fluence. We show that a particularly advantageous way of improving efficiency within those constraints is operation at cryogenic temperature. Based on the numerical findings we present a concept for a scalable amplifier based on an end-pumped, cryogenic, gas-cooled multi-slab architecture.

Influence of Off-Centre Operation on the Performance of HTS Maglev

NASA Astrophysics Data System (ADS)

Gou, Y.; He, D.; Zheng, J.; Ye, C.; Xu, Y.; Sun, R.; Che, T.; Deng, Z.

2014-03-01

Owing to instinctive self-stable levitation characteristics, high-temperature superconducting (HTS) maglev using bulk high-temperature superconductors attracts more and more attention from scientists and engineers around the world. In this paper, the levitation force relaxation and guidance force characteristics of a Y-Ba-Cu-O levitation unit with different eccentric distances (EDs) off the center of the permanent magnet guideway were experimentally investigated under field-cooling (FC) conditions. Experimental results indicate that the levitation force slightly increases at small EDs firstly, but degrades with further increasing of EDs. However, the maximum guidance force and its stiffness exhibit enhancement in moderate ED range. The results demonstrate that a properly designed initial FC eccentric distance is important for the practical applications of HTS maglev according to specific requirements like running in curve lines.

Transport temperatures observed during the commercial transportation of animals.

PubMed

Fiore, Gianluca; Hofherr, Johann; Natale, Fabrizio; Mainetti, Sergio; Ruotolo, Espedito

2012-01-01

Current temperature standards and those proposed by the European Food Safety Authority (EFSA) were compared with the actual practices of commercial transport in the European Union. Temperature and humidity records recorded for a year on 21 vehicles over 905 journeys were analysed. Differences in temperature and humidity recorded by sensors at four different positions in the vehicles exceeded 10°C between the highest and lowest temperatures in nearly 7% of cases. The number and position of temperature sensors are important to ensure the correct representation of temperature conditions in the different parts of a vehicle. For all journeys and all animal categories, a relatively high percentage of beyond threshold temperatures can be observed in relation to the temperature limits of 30°C and 5°C. Most recorded temperature values lie within the accepted tolerance of ±5°C stipulated in European Community Regulation (EC) 1/2005. The temperature thresholds proposed by EFSA would result in a higher percentage of non-compliant conditions which are more pronounced at the lower threshold, compared to the thresholds laid down in Regulation (EC) 1/2005. With respect to the different animal categories, the non-compliant temperature occurrences were more frequent in pigs and sheep, in particular with regard to the thresholds proposed by EFSA.

Nitrogen-doped carbon spheres: A new high-energy-density and long-life pseudo-capacitive electrode material for electrochemical flow capacitor.

PubMed

Hou, Shujin; Wang, Miao; Xu, Xingtao; Li, Yandong; Li, Yanjiang; Lu, Ting; Pan, Likun

2017-04-01

One of the most challenging issues in developing electrochemical flow capacitor (EFC) technology is the design and synthesis of active electrode materials with high energy density and long cycle life. However, in practical cases, the energy density and cycle ability obtained currently cannot meet the practical need. In this work, we propose a new active material, nitrogen-doped carbon spheres (NCSs), as flowable electrodes for EFC application. The NCSs were prepared via one-pot hydrothermal synthesis in the presence of resorcinol/formaldehyde as carbon precursors and melamine as nitrogen precursor, followed by carbonization in nitrogen flow at various temperatures. The results of EFC experiments demonstrate that NCSs obtained at 800°C exhibit a high energy density of 13.5Whkg -1 and an excellent cycle ability, indicating the superiority of NCSs for EFC application. Copyright © 2016 Elsevier Inc. All rights reserved.

System Being Developed to Measure the Rotordynamic Characteristics of Air Foil Bearings

NASA Technical Reports Server (NTRS)

Howard, Samuel A.; DellaCorte, Christopher; Valco, Mark J.

2000-01-01

Because of the many possible advantages of oil-free engine operation, interest in using air lubricated foil-bearing technology in advanced oil-free engine concepts has recently increased. The Oil-Free Turbomachinery Program at the NASA Glenn Research Center at Lewis Field has partially driven this recent push for oil-free technology. The program's goal of developing an innovative, practical, oil-free gas turbine engine for aeropropulsion began with the development of NASA's high-temperature solid-lubricant coating, PS304. This coating virtually eliminates the life-limiting wear that occurs during the startup and shutdown of the bearings. With practically unlimited life, foil air bearings are now very attractive to rotating machinery designers for use in turbomachinery. Unfortunately, the current knowledge base of these types of bearings is limited. In particular, the understanding of how these types of bearings contribute to the rotordynamic stability of turbomachinery is insufficient for designers to design with confidence. Recent work in oil-free turbomachinery has concentrated on advancing the understanding of foil bearings. A high-temperature fiber-optic displacement probe system and measurement method were developed to study the effects of speed, load, temperature, and other environmental issues on the stiffness characteristics of air foil bearings. Since high temperature data are to be collected in future testing, the testing method was intentionally simplified to minimize the need for expensive test hardware. The method measures the displacement induced upon a bearing in response to an applied perturbation load. The early results of these studies, which are shown in the accompanying figure, indicate trends in steady state stiffness that suggest stiffness increases with load and decreases with speed. It can be seen, even from these data, that stiffness is not expected to change by orders of magnitude over the normal operating range of most turbomachinery; a promising sign for their eventual integration into oil-free turbomachines. Planned future testing will generate similar plots for stiffness changes with temperature and geometry, as well as damping data. The data collected by this method represent a critical step toward understanding how to successfully apply foil air bearings to future oil-free turbomachinery systems.

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

Wang, Hui; Chen, Yan; Hood, Zachary D.

All-solid-state sodium batteries, using abundant sodium resources and solid electrolyte, hold much promise for safe, low cost, large-scale energy storage. To realize the practical applications of all solid Na-ion batteries at ambient temperature, the solid electrolytes are required to have high ionic conductivity, chemical stability, and ideally, easy preparation. Ceramic electrolytes show higher ionic conductivity than polymers, but they often require extremely stringent synthesis conditions, either high sintering temperature above 1000 C or long-time, low-energy ball milling. Herein, we report a new synthesis route for Na 3SbS 4, a novel Na superionic conductor that needs much lower processing temperature belowmore » 200 C and easy operation. This new solid electrolyte exhibits a remarkable ionic conductivity of 1.05 mS cm -1 at 25 °C and is chemically stable under ambient atmosphere. In conclusion, this synthesis process provides unique insight into the current state-of-the-art solid electrolyte preparation and opens new possibilities for the design of similar materials.« less

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

Zhan, Wangcheng; He, Qian; Liu, Xiaofei

Supported gold (Au) nanocatalysts hold great promise for heterogeneous catalysis; however, their practical application is greatly hampered by poor thermodynamic stability. Herein, a general synthetic strategy is reported where discrete metal nanoparticles are made resistant to sintering, preserving their catalytic activities in high-temperature oxidation processes. Taking advantage of the unique coating chemistry of dopamine, sacrificial carbon layers are constructed on the material surface, stabilizing the supported catalyst. Upon annealing at high temperature under an inert atmosphere, the interactions between support and metal nanoparticle are dramatically enhanced, while the sacrificial carbon layers can be subsequently removed through oxidative calcination in air.more » Owing to the improved metal-support contact and strengthened electronic interactions, the resulting Au nanocatalysts are resistant to sintering and exhibit excellent durability for catalytic combustion of propylene at elevated temperatures. Moreover, the facile synthetic strategy can be extended to the stabilization of other supported catalysts on a broad range of supports, providing a general approach to enhancing the thermal stability and sintering resistance of supported nanocatalysts.« less

Above 400-K robust perpendicular ferromagnetic phase in a topological insulator

PubMed Central

Tang, Chi; Chang, Cui-Zu; Zhao, Gejian; Liu, Yawen; Jiang, Zilong; Liu, Chao-Xing; McCartney, Martha R.; Smith, David J.; Chen, Tingyong; Moodera, Jagadeesh S.; Shi, Jing

2017-01-01

The quantum anomalous Hall effect (QAHE) that emerges under broken time-reversal symmetry in topological insulators (TIs) exhibits many fascinating physical properties for potential applications in nanoelectronics and spintronics. However, in transition metal–doped TIs, the only experimentally demonstrated QAHE system to date, the QAHE is lost at practically relevant temperatures. This constraint is imposed by the relatively low Curie temperature (Tc) and inherent spin disorder associated with the random magnetic dopants. We demonstrate drastically enhanced Tc by exchange coupling TIs to Tm3Fe5O12, a high-Tc magnetic insulator with perpendicular magnetic anisotropy. Signatures showing that the TI surface states acquire robust ferromagnetism are revealed by distinct squared anomalous Hall hysteresis loops at 400 K. Point-contact Andreev reflection spectroscopy confirms that the TI surface is spin-polarized. The greatly enhanced Tc, absence of spin disorder, and perpendicular anisotropy are all essential to the occurrence of the QAHE at high temperatures. PMID:28691097

A Highly Practical Copper(I)/TEMPO Catalyst System for Chemoselective Aerobic Oxidation of Primary Alcohols

PubMed Central

Hoover, Jessica M.; Stahl, Shannon S.

2011-01-01

Aerobic oxidation reactions have been the focus of considerable attention, but their use in mainstream organic chemistry has been constrained by limitations in their synthetic scope and by practical factors, such as the use of pure O2 as the oxidant or complex catalyst synthesis. Here, we report a new (bpy)CuI/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary alcohols, including allylic, benzylic and aliphatic derivatives, to the corresponding aldehydes using readily available reagents, at room temperature with ambient air as the oxidant. The catalyst system is compatible with a wide range of functional groups and the high selectivity for 1° alcohols enables selective oxidation of diols that lack protecting groups. PMID:21861488

The potential of land management to decrease global warming from climate change

NASA Astrophysics Data System (ADS)

Mayer, A.; Hausfather, Z.; Jones, A. D.; Silver, W. L.

2016-12-01

Recent evidence suggests that negative emissions (i.e. sequestration) is critical to slow climate change (IPCC, 2013; Gasser et al, 2015). Agricultural (crop and grazing) lands have the potential to act as a significant carbon sink. These ecosystems cover a significant proportion of the global land surface, and are largely degraded with regard to soil carbon due to previous management practices (Bai et al, 2008). However, few studies have examined the required scale of land management interventions that would be required to make a significant contribution to a portfolio of efforts aimed at limiting anthropogenic influences on global mean temperature. To address this, we modelled the quantitative effect of a range of soil carbon sequestration rates on global temperature to 2100. Results showed that by assuming a baseline emissions scenario outlined in RCP 2.6, the sequestration of an additional 0.7 Pg C per year through improved agricultural land management practices would produce a reduction of 0.1 degrees C from predicted global temperatures by the year 2100. We also compiled previous estimates of global carbon sequestration potential of agricultural soils to compare with our theoretical prediction to determine whether carbon sequestration through existing land management practices has potential to significantly reduce global temperatures. Assuming long-term soil carbon uptake, the combined potential of agricultural land management-based mitigation approaches exceeded 0.25 degrees C warming reduction by the year 2100. However, results were highly sensitive to potential carbon saturation, defined as the maximum threshold for carbon storage in soil. Our results suggest that current land management technologies and available land area exist and could make a measureable impact on warming reduction. Results also highlighted potential carbon saturation as a key gap in knowledge.

Moisture uptake of polyoxyethylene glycol glycerides used as matrices for drug delivery: kinetic modelling and practical implications.

PubMed

Qi, Sheng; Belton, Peter; McAuley, William; Codoni, Doroty; Darji, Neerav

2013-04-01

Gelucire 50/13, a polyoxyethylene glycol glyceride mixture, has been widely used in drug delivery, but its moisture uptake behaviour is still poorly understood. In this study, the effects of relative humidity, temperature, and drug incorporation on the moisture uptake of Gelucire are reported in relation to their practical implications for preparation of solid dispersions using this material. DVS combined with kinetics modelling was used as the main experimental method to study the moisture uptake behaviour of Gelucire. Thermal and microscopic methods were employed to investigate the effect of moisture uptake on the physical properties of the material and drug loaded solid dispersions. The moisture uptake by Gelucire 50/13 is temperature and relative humidity dependent. At low temperatures and low relative humidities, moisture sorption follows a GAB model. The model fitting indicated that at high relative humidities the sorption is a complex process, potentially involving PEG being dissolved and the PEG solution acting as solvent to dissolve other components. Careful control of the storage and processing environmental conditions are required when using Gelucire 50/13. The incorporation of model drugs not only influences the moisture uptake capacity of Gelucire 50/13 but also the solidification behaviour.

Temperature compensation of ultrasonic velocity during the malolactic fermentation process

NASA Astrophysics Data System (ADS)

Amer, M. A.; Novoa-Díaz, D.; Chávez, J. A.; Turó, A.; García-Hernández, M. J.; Salazar, J.

2015-12-01

Ultrasonic properties of materials present a strong dependence on temperature and in turn the ultrasonic velocity of propagation in the material under test. It is precisely for this reason that most ultrasonic measurements are often carried out with thermostated samples by using either water tanks or climate chambers. This approach is viable in a laboratory and when the measured or characterized samples are relatively small. However, this procedure is highly improbable to be applied when in situ measurements in industrial environments must be performed. This goes for the case of, for example, ultrasonic velocity measurements in wine while it is performing malolactic fermentation inside a tank of hundreds of thousands of litres. In this paper two different practical approaches to temperature compensation are studied. Then, the two temperature compensation methods are applied to the measured ultrasonic velocity values along a whole malolactic fermentation process. The results of each method are discussed.

NBS/NIST Gas Thermometry From 0 to 660 °C

PubMed Central

Schooley, J. F.

1990-01-01

In the NBS/NIST Gas Thermometry program, constant-volume gas thermometers, a unique mercury manometer, and a highly accurate thermal expansion apparatus have been employed to evaluate temperatures on the Kelvin Thermodynamic Temperature Scale (KTTS) that correspond to particular temperatures on the 1968 International Practical Temperature Scale (IPTS-68). In this paper, we present a summary of the NBS/NIST Gas Thermometry project, which originated with planning activities in the late 1920s and was completed by measurements of the differences t(KTTS)-t(IPTS-68) in the range 0 to 660 °C. Early results of this project were the first to demonstrate the surprisingly large inaccuracy of the IPTS-68 with respect to the KTTS above 0 °C. Advances in several different measurement techniques, development of new, specialized instruments, and two distinct sets of gas thermometry observations have resulted from the project. PMID:28179778

Kinetic, Spectroscopic, and Theoretical Assessment of Associative and Dissociative Methanol Dehydration Routes in Zeolites

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

Jones, Andrew J.; Iglesia, Enrique

Mechanistic interpretations of rates and in situ IR spectra combined with density functionals that account for van der Waals interactions of intermediates and transition states within confining voids show that associative routes mediate the formation of dimethyl ether from methanol on zeolitic acids at the temperatures and pressures of practical dehydration catalysis. Methoxy-mediated dissociative routes become prevalent at higher temperatures and lower pressures, because they involve smaller transition states with higher enthalpy, but also higher entropy, than those in associative routes. These enthalpy–entropy trade-offs merely reflect the intervening role of temperature in activation free energies and the prevalence of moremore » complex transition states at low temperatures and high pressures. This work provides a foundation for further inquiry into the contributions of H-bonded methanol and methoxy species in homologation and hydrocarbon synthesis reactions from methanol.« less

Room temperature current injection polariton light emitting diode with a hybrid microcavity.

PubMed

Lu, Tien-Chang; Chen, Jun-Rong; Lin, Shiang-Chi; Huang, Si-Wei; Wang, Shing-Chung; Yamamoto, Yoshihisa

2011-07-13

The strong light-matter interaction within a semiconductor high-Q microcavity has been used to produce half-matter/half-light quasiparticles, exciton-polaritons. The exciton-polaritons have very small effective mass and controllable energy-momentum dispersion relation. These unique properties of polaritons provide the possibility to investigate the fundamental physics including solid-state cavity quantum electrodynamics, and dynamical Bose-Einstein condensates (BECs). Thus far the polariton BEC has been demonstrated using optical excitation. However, from a practical viewpoint, the current injection polariton devices operating at room temperature would be most desirable. Here we report the first realization of a current injection microcavity GaN exciton-polariton light emitting diode (LED) operating under room temperature. The exciton-polariton emission from the LED at photon energy 3.02 eV under strong coupling condition is confirmed through temperature-dependent and angle-resolved electroluminescence spectra.

Robust label-free biosensing using microdisk laser arrays with on-chip references.

PubMed

Wondimu, S F; Hippler, M; Hussal, C; Hofmann, A; Krämmer, S; Lahann, J; Kalt, H; Freude, W; Koos, C

2018-02-05

Whispering-gallery mode (WGM) microdisk lasers show great potential for highly sensitive label-free detection in large-scale sensor arrays. However, when used in practical applications under normal ambient conditions, these devices suffer from temperature fluctuations and photobleaching. Here we demonstrate that these challenges can be overcome by a novel referencing scheme that allows for simultaneous compensation of temperature drift and photobleaching. The technique relies on reference structures protected by locally dispensed passivation materials, and can be scaled to extended arrays of hundreds of devices. We prove the viability of the concept in a series of experiments, demonstrating robust and sensitive label-free detection over a wide range of constant or continuously varying temperatures. To the best of our knowledge, these measurements represent the first demonstration of biosensing in active WGM devices with simultaneous compensation of both photobleaching and temperature drift.

Practical fit functions for transport critical current versus field magnitude and angle data from (RE)BCO coated conductors at fixed low temperatures and in high magnetic fields

NASA Astrophysics Data System (ADS)

Hilton, D. K.; Gavrilin, A. V.; Trociewitz, U. P.

2015-07-01

Applications of (RE = Y, Gd)BCO coated conductors for the generation of high magnetic fields are increasing sharply, this while (RE)BCO coated conductors themselves are evolving rapidly. This article describes and demonstrates recently developed and applied mathematical models that systematically and comprehensively characterize the transport critical current angular dependence of a batch of (RE)BCO coated conductor in high magnetic fields at fixed temperatures with an uncertainty of 10% or better. The model development was based on analysis of experimental data sets from various published sources and coated conductors with different microstructures. These derivations directly are applicable to the accurate prediction of the performance in high magnetic fields of coils wound with (RE)BCO coated conductors. In particular, a nonlinear fit is discussed in this article of transport critical current at T = 4.2 K versus field and angle data. This fit was used to estimate the hysteresis losses of (RE)BCO coated conductors in high magnetic fields, and to design the inserts wound with such conductors of the all-superconducting 32 T magnet being constructed at the NHMFL. A series of such fits, recently developed at several fixed temperatures, continues to be used to simulate the quench behavior of that magnet.

Fabrication of photovoltaic laser energy converterby MBE

NASA Technical Reports Server (NTRS)

Lu, Hamilton; Wang, Scott; Chan, W. S.

1993-01-01

A laser-energy converter, fabricated by molecular beam epitaxy (MBE), was developed. This converter is a stack of vertical p-n junctions connected in series by low-resistivity, lattice matched CoSi2 layers to achieve a high conversion efficiency. Special high-temperature electron-beam (e-beam) sources were developed especially for the MBE growth of the junctions and CoSi2 layers. Making use of the small (greater than 1.2 percent) lattice mismatch between CoSi2 and Si layers, high-quality and pinhole-free epilayers were achieved, providing a capability of fabricating all the junctions and connecting layers as a single growth process with one pumpdown. Well-defined multiple p-n junctions connected by CoSi2 layers were accomplished by employing a low growth temperature (greater than 700 C) and a low growth rate (less than 0.5 microns/hour). Producing negligible interdiffusion, the low growth temperature and rate also produced negligible pinholes in the CoSi2 layers. For the first time, a stack of three p-n junctions connected by two 10(exp -5) Ohm-cm CoSi2 layers was achieved, meeting the high conversion efficiency requirement. This process can now be optimized for high growth rate to form a practical converter with 10 p-n junctions in the stack.

Caracterisation des Ondes Radar de Surface par la Simulation Numerique et les Mesures GPR pour l'Auscultation en

NASA Astrophysics Data System (ADS)

Filali, Bilai

Graphene, as an advanced carbon nano-structure, has attracted a deluge of interest of scholars recently because of it's outstanding mechanical, electrical and thermal properties. There are several different ways to synthesis graphene in practical ways, such as Mechanical Exfoliation, Chemical Vapor Deposition (CVD), and Anodic Arc discharge. In this thesis a method of graphene synthesis in plasma will be discussed, in which this synthesis method is supported by the erosion of the anode material. This graphene synthesis method is one of the most practical methods which can provide high production rate. High purity of graphene flakes have been synthesized with an anodic arc method under certain pressure (about 500 torr). Raman spectrometer, Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM) have been utilized for characterization of the synthesis products. Arc produced graphene and commercially available graphene was compared by those machine and the difference lies in the number of layers, the thicknesses of each layer and the shape of the structure itself. Temperature dependence of the synthesis procedure has been studied. It has been found that the graphene can be produced on a copper foil substrate under temperatures near the melting point of copper. However, with a decrease in substrate temperature yields a transformation of the synthesized graphene into amorphous carbon. Glow discharge was utilized to functionalize grapheme. SEM and EDS observation indicated increases of oxygen content in the graphene after its exposure to glow discharge.

Diagnosis and management of temperature abnormality in ICUs: a EUROBACT investigators' survey.

PubMed

Niven, Daniel J; Laupland, Kevin B; Tabah, Alexis; Vesin, Aurélien; Rello, Jordi; Koulenti, Despoina; Dimopoulos, George; de Waele, Jan; Timsit, Jean-Francois

2013-12-10

Although fever and hypothermia are common abnormal physical signs observed in patients admitted to intensive care units (ICU), little data exist on their optimal management. The objective of this study was to describe contemporary practices and determinants of management of temperature abnormalities among patients admitted to ICUs. Site leaders of the multi-national EUROBACT study were surveyed regarding diagnosis and management of temperature abnormalities among patients admitted to their ICUs. Of the 162 ICUs originally included in EUROBACT, responses were received from 139 (86%) centers in 23 countries in Europe (117), South America (8), Asia (5), North America (4), Australia (3) and Africa (2). A total of 117 (84%) respondents reported use of a specific temperature threshold in their ICU to define fever. A total of 14 different discrete levels were reported with a median of 38.2°C (inter-quartile range, IQR, 38.0°C to 38.5°C). The use of thermometers was protocolized in 91 (65%) ICUs and a wide range of methods were reportedly used, with axillary, tympanic and urinary bladder sites as the most common as primary modalities. Only 31 (22%) of respondents indicated that there was a formal written protocol for temperature control among febrile patients in their ICUs. In most or all cases practice was to control temperature, to use acetaminophen, and to perform a full septic workup in febrile patients and that this was usually directed by physician order. While reported practice was to treat nearly all patients with neurological impairment and most patients with acute coronary syndromes and infections, severe sepsis and septic shock, this was not the case for most patients with liver failure and fever. A wide range of definitions and management practices were reported regarding temperature abnormalities in the critically ill. Documenting temperature abnormality management practices, including variability in clinical care, is important to inform planning of future studies designed to optimize infection and temperature management strategies in the critically ill.

Benefits of using vaccines out of the cold chain: delivering meningitis A vaccine in a controlled temperature chain during the mass immunization campaign in Benin.

PubMed

Zipursky, Simona; Djingarey, Mamoudou Harouna; Lodjo, Jean-Claude; Olodo, Laifoya; Tiendrebeogo, Sylvestre; Ronveaux, Olivier

2014-03-14

In October 2012, the Meningococcal A conjugate vaccine MenAfriVac was granted a label variation to allow for its use in a controlled temperature chain (CTC), at temperatures of up to 40°C for not more than four days. This paper describes the first field use of MenAfriVac in a CTC during a campaign in Benin, December 2012, and assesses the feasibility and acceptability of the practice. We implemented CTC in one selected district, Banikoara (target population of 147,207; 1-29 years of age), across 14 health facilities and 150 villages. We monitored the CTC practice using temperature indicators and daily monitoring sheets. At the end of the campaign we conducted a face-to-face survey to assess vaccinators' and supervisors' experience with CTC. A mix of strategies were implemented in the field to maximize the benefits from CTC practice, depending on the distance from health centre to populations and the availability of a functioning refrigerator in the health centre. Coverage across Banikoara was 105.7%. Over the course of the campaign only nine out of approx. 15,000 vials were discarded due to surpassing the 4 day CTC limit and no vial was discarded because of exposure to a temperature higher than 40°C or due to the Vaccine Vial Monitor (VVM) reaching its endpoint. Overall confidence and perceived usefulness of the CTC approach were very high among vaccinators and supervisors. Vaccinators and supervisors see clear benefits from the CTC approach in low income settings, especially in hard-to-reach areas or where cold chain is weak. Taking advantage of the flexibility offered by CTC opens the door for the implementation of new immunization strategies to ensure all those at risk are protected. Copyright © 2014. Published by Elsevier Ltd.

Mapping spatial and temporal variation of stream water temperature in the upper Esopus Creek watershed

NASA Astrophysics Data System (ADS)

Chien, H.; McGlinn, L.

2017-12-01

The upper Esopus Creek and its tributary streams located in the Catskill Mountain region of New York State provide habitats for cold-adapted aquatic species. However, ongoing global warming may change the stream water temperature within a watershed and disturb the persistence of coldwater habitats. Characterizing thermal regimes within the upper Esopus Creek watershed is important to provide information of thermally suitable habitats for aquatic species. The objectives of this study are to measure stream water temperature and map thermal variability among tributaries to the Esopus Creek and within Esopus Creek. These objectives will be achieved by measuring stream water temperature for at least two years. More than 100 water temperature data loggers have been placed in the upper Esopus Creek and their tributaries to collect 30-minute interval water temperatures. With the measured water temperature, we will use spatial interpolation in ArcGIS to create weekly and monthly water temperature surface maps to evaluate the thermal variation over time and space within the upper Esopus Creek watershed. We will characterize responsiveness of water temperature in tributary streams to air temperature as well. This information of spatial and temporal variation of stream water temperature will assist stream managers with prioritizing management practices that maintain or enhance connectivity of thermally suitable habitats in high priority areas.

Plasma protein denaturation with graded heat exposure.

PubMed

Vazquez, R; Larson, D F

2013-11-01

During cardiopulmonary bypass (CPB), perfusion at tepid temperatures (33-35 °C) is recommended to avoid high temperature cerebral hyperthermia during and after the operation. However, the ideal temperature for uncomplicated adult cardiac surgery is an unsettled question. Typically, the heat exchanger maximum temperature is monitored between 40-42 °C to prevent denaturation of plasma proteins, but studies have not been performed to make these conclusions. Therefore, our hypothesis was to determine the temperature in which blood plasma protein degradation occurs after 2 hours of heat exposure. As a result, blood plasma proteins were exposed to heat in the 37-50 °C range for 2 hours. Plasma protein samples were loaded onto an 8-12% gradient gel for SDS-PAGE and low molecular weight plasma protein degradation was detected with graded heat exposure. Protein degradation was first detected between 43-45 °C of heat exposure. This study supports the practice of monitoring the heat exchanger between 40-42 °C to prevent denaturation of plasma proteins.

Modelling climate change, land-use change and phosphorus reduction impacts on phytoplankton in the River Thames (UK)

NASA Astrophysics Data System (ADS)

Bussi, Gianbattista; Whitehead, Paul; Dadson, Simon

2016-04-01

In this study, we assess the impact of changes in precipitation and temperature on the phytoplankton concentration of the River Thames (UK) by means of a physically-based model. A scenario-neutral approach was employed to evaluate the effects of climate variability on flow, phosphorus concentration and phytoplankton concentration. In particular, the impact of uniform changes in precipitation and temperature on five groups of phytoplankton (diatoms and large chlorophytes, other chlorophytes, picoalgae, Microcystis-like cyanobacteria and other cyanobacteria) was assessed under three different land-use/land-management scenarios (1 - current land use and phosphorus reduction practices; 2 - expansion of agricultural land and current phosphorus reduction practices; 3 - expansion of agricultural land and optimal phosphorus reduction practices). The model results were assessed within the framework of future climate projections, using the UK Climate Projections 09 (UKCP09) for the 2030s. The results of the model demonstrate that an increase in average phytoplankton concentration due to climate change is highly likely to occur, and its magnitude varies depending on the river reach. Cyanobacteria show significant increases under future climate change and land-use change. An expansion of intensive agriculture accentuates the growth in phytoplankton, especially in the upper reaches of the River Thames. However, an optimal phosphorus removal mitigation strategy, which combines reduction of fertiliser application and phosphorus removal from wastewater, can help to reduce this increase in phytoplankton concentration, and in some cases, compensate for the effect of rising temperature.

Temperature of surface waters in the conterminous United States

USGS Publications Warehouse

Blakey, James F.

1966-01-01

Temperature is probably the most important, but least discussed, parameter in determining water quality. The purpose of this report is to present the average or most probable temperatures of surface waters in the conterminous United States and to cite factors that affect and are affected by water temperature. Temperature is related, usually directly, to all the chemical, physical, and biological properties of water. The ability of water to dissolve or precipitate materials is temperature dependent, the ability of water to transport or deposit suspended material is temperature dependent, and the aquatic life of a lake or stream may thrive or die because of the water temperature.Everyone is concerned, though often unknowingly, about water temperature. The amount and type of treatment necessary for a municipal supply are temperature dependent; therefore it affects the consumer cost. Temperature determines the volume of cooling water needed for industrial processes and steampower generation. Conservation and recreation practices are affected by water temperature, and the farmers' irrigation practices and livestock production may be affected by the water temperature.

Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams (Final Report)

EPA Science Inventory

This final report is a technical "best practices" document describing sensor deployment for and collection of continuous temperature and flow data at ungaged sites in wadeable streams. This document addresses questions related to equipment needs; configuration, placement, and ins...

Exertional Heat Illnesses and Environmental Conditions During High School Football Practices.

PubMed

Tripp, Brady L; Eberman, Lindsey E; Smith, Michael Seth

2015-10-01

Guidelines for preventing exertional heat illnesses (EHIs) during extreme heat stress should be specific to regional environments, age, and sport and should be based on evidence of reducing the risk. Each year in the United States, over 1 million high school football players practice in the August heat; however, no published data describe the incidence of EHIs in these athletes. To describe the environmental conditions and incidence of EHIs during high school football practices over a 3-month period. Descriptive epidemiology study. For a 3-month period (August-October), athletic trainers at 12 high schools in North Central Florida recorded the practice time and length, environmental conditions (wet-bulb globe temperature), and incidences of EHIs in varsity football athletes. Athletes suffered 57 total EHIs during 29,759 athlete-exposures (AEs) for the 3-month data collection period (rate = 1.92/1000 AEs). August accounted for the majority of all EHIs, with 82.5% (47/57) and the highest rate (4.35/1000 AEs). Of total heat illnesses, heat cramps accounted for 70.2% (40/57), heat exhaustion 22.8% (13/57), and heat syncope 7.0% (4/57). The odds ratio indicated that athletes in August practices that lasted longer than the recommended 3 hours were 9.84 times more likely to suffer a heat illness than those in practices lasting ≤3 hours. The highest rate of EHIs was during August. Practices in August that exceeded the recommended 3 hours were associated with a greater risk of heat illnesses. The overall rate of EHIs was lower for the high school football athletes observed in the study compared with that reported for collegiate football athletes in the region. The low rates of EHIs recorded suggest that the prevention guidelines employed by sports medicine teams are appropriate for the region and population. Team physicians and athletic trainers should employ evidence-based, region- and population-specific EHI prevention guidelines. Sports medicine teams, coaches, and athletes should be aware of the increased risk of EHIs during August practices and the risk of prolonged practices during August. © 2015 The Author(s).

Constitutive Modeling of High-Temperature Flow Behavior of an Nb Micro-alloyed Hot Stamping Steel

NASA Astrophysics Data System (ADS)

Zhang, Shiqi; Feng, Ding; Huang, Yunhua; Wei, Shizhong; Mohrbacher, Hardy; Zhang, Yue

2016-03-01

The thermal deformation behavior and constitutive models of an Nb micro-alloyed 22MnB5 steel were investigated by conducting isothermal uniaxial tensile tests at the temperature range of 873-1223 K with strain rates of 0.1-10 s-1. The results indicated that the investigated steel showed typical work hardening and dynamic recovery behavior during hot deformation, and the flow stress decreased with a decrease in strain rate and/or an increase in temperature. On the basis of the experimental data, the modified Johnson-Cook (modified JC), modified Norton-Hoff (modified NH), and Arrhenius-type (AT) constitutive models were established for the subject steel. However, the flow stress values predicted by these three models revealed some remarkable deviations from the experimental values for certain experimental conditions. Therefore, a new combined modified Norton-Hoff and Arrhenius-type constitutive model (combined modified NH-AT model), which accurately reflected both the work hardening and dynamic recovery behavior of the subject steel, was developed by introducing the modified parameter k ɛ. Furthermore, the accuracy of these constitutive models was assessed by the correlation coefficient, the average absolute relative error, and the root mean square error, which indicated that the flow stress values computed by the combined modified NH-AT model were highly consistent with the experimental values (R = 0.998, AARE = 1.63%, RMSE = 3.85 MPa). The result confirmed that the combined modified NH-AT model was suitable for the studied Nb micro-alloyed hot stamping steel. Additionally, the practicability of the new model was also verified using finite element simulations in ANSYS/LS-DYNA, and the results confirmed that the new model was practical and highly accurate.

A Two-Dimensional Manganese Gallium Nitride Surface Structure Showing Ferromagnetism at Room Temperature.

PubMed

Ma, Yingqiao; Chinchore, Abhijit V; Smith, Arthur R; Barral, María Andrea; Ferrari, Valeria

2018-01-10

Practical applications of semiconductor spintronic devices necessitate ferromagnetic behavior at or above room temperature. In this paper, we demonstrate a two-dimensional manganese gallium nitride surface structure (MnGaN-2D) which is atomically thin and shows ferromagnetic domain structure at room temperature as measured by spin-resolved scanning tunneling microscopy and spectroscopy. Application of small magnetic fields proves that the observed magnetic domains follow a hysteretic behavior. Two initially oppositely oriented MnGaN-2D domains are rotated into alignment with only 120 mT and remain mostly in alignment at remanence. The measurements are further supported by first-principles theoretical calculations which reveal highly spin-polarized and spin-split surface states with spin polarization of up to 95% for manganese local density of states.

Practical acoustic thermometry with twin-tube and single-tube sensors

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

De Podesta, M.; Sutton, G.; Edwards, G.

2015-07-01

Accurate measurement of high temperatures in a nuclear environment presents unique challenges. All secondary techniques inevitably drift because the thermometric materials in thermocouples and resistance sensors are sensitive not just to temperature, but also their own chemical and physical composition. The solution is to use primary methods that rely on fundamental links between measurable physical properties and temperature. In the nuclear field the best known technique is the measurement of Johnson Noise in a resistor (See Paper 80 at this conference). In this paper we describe the measurement of temperature in terms of the speed of sound in a gasmore » confined in a tube - an acoustic waveguide. Acoustic thermometry is the most accurate technique of primary thermometry ever devised with the best uncertainty of measurement below 0.001 C. In contrast, the acoustic technique described in this work has a much larger uncertainty, approximately 1 deg. C. But the cost and ease of use are improved by several orders of magnitude, making implementation eminently practical. We first describe the basic construction and method of operation of thermometers using twin-tubes and single tubes. We then present results using a twin-tube design showing that showing long term stability (i.e. no detectable drift) at 700 deg. C over periods of several weeks. We then outline how the technique may be developed for different nuclear applications. (authors)« less

High-Quality In-Plane Aligned CsPbX3 Perovskite Nanowire Lasers with Composition-Dependent Strong Exciton-Photon Coupling.

PubMed

Wang, Xiaoxia; Shoaib, Muhammad; Wang, Xiao; Zhang, Xuehong; He, Mai; Luo, Ziyu; Zheng, Weihao; Li, Honglai; Yang, Tiefeng; Zhu, Xiaoli; Ma, Libo; Pan, Anlian

2018-06-14

Cesium lead halide perovskite nanowires have emerged as promising low-dimensional semiconductor structures for integrated photonic applications. Understanding light-matter interactions in a nanowire cavity is of both fundamental and practical interest in designing low-power-consumption nanoscale light sources. In this work, high-quality in-plane aligned halide perovskite CsPbX 3 (X = Cl, Br, I) nanowires are synthesized by a vapor growth method on an annealed M-plane sapphire substrate. Large-area nanowire laser arrays have been achieved based on the as-grown aligned CsPbX 3 nanowires at room temperature with quite low pumping thresholds, very high quality factors, and a high degree of linear polarization. More importantly, it is found that exciton-polaritons are formed in the nanowires under the excitation of a pulsed laser, indicating a strong exciton-photon coupling in the optical microcavities made of cesium lead halide perovskites. The coupling strength in these CsPbX 3 nanowires is dependent on the atomic composition, where the obtained room-temperature Rabi splitting energy is ∼210 ± 13, 146 ± 9, and 103 ± 5 meV for the CsPbCl 3 , CsPbBr 3 , and CsPbI 3 nanowires, respectively. This work provides fundamental insights for the practical applications of all-inorganic perovskite CsPbX 3 nanowires in designing light-emitting devices and integrated nanophotonic systems.

Practical development of continuous supercritical fluid process using high pressure and high temperature micromixer

NASA Astrophysics Data System (ADS)

Kawasaki, Shin-Ichiro; Sue, Kiwamu; Ookawara, Ryuto; Wakashima, Yuichiro; Suzuki, Akira

2015-12-01

In the synthesis of metal oxide fine particles by continuous supercritical hydrothermal method, the particle characteristics are greatly affected by not only the reaction conditions (temperature, pressure, residence time, concentration, etc.), but also the heating rate from ambient to reaction temperature. Therefore, the heating method by direct mixing of starting solution at room temperature with supercritical water is a key technology for the particle production having smaller size and narrow distribution. In this paper, mixing engineering study through comparison between conventional T-shaped mixers and recently developed swirl mixers was carried out in the hydrothermal synthesis of NiO nanoparticles from Ni(NO3)2 aqueous solution at 400 °C and 30 MPa. Inner diameter in the mixers and total flow rates were varied. Furthermore, the heating rate was calculated by computational fluid dynamics (CFD) simulation. Relationship between the heating rate and the average particle size were discussed. It was clarified that the miniaturization of mixer inner diameter and the use of the swirl flow were effective for improving mixing performance and contributed to produce small and narrow distribution particle under same experimental condition of flow rate, temperature, pressure, residence time, and concentration of the starting materials. We have focused the mixer optimization due to a difference in fluid viscosity.

Temperature-dependent refractive index measurements of L-BBH2 glass for the Subaru CHARIS integral field spectrograph

NASA Astrophysics Data System (ADS)

Leviton, Douglas B.; Miller, Kevin H.; Quijada, Manuel A.; Groff, Tyler D.

2015-09-01

Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we have made the first cryogenic measurements of absolute refractive index for Ohara L-BBH2 glass to enable the design of a prism for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) at the Subaru telescope. L-BBH2 is employed in CHARIS's prism design for improving the spectrograph's dispersion uniformity. Index measurements were made at temperatures from 110 to 305 K at wavelengths from 0.46 to 3.16 μm. We report absolute refractive index (n), dispersion (dn/dλ), and thermo-optic coefficient (dn/dT) for this material along with estimated single measurement uncertainties as a function of wavelength and temperature. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures within applicable ranges. This paper also speaks of the challenges in measuring index for a material which is not available in sufficient thickness to fabricate a typical prism for measurement in CHARMS, the tailoring of the index prism design that allowed these index measurements to be made, and the remarkable results obtained from that prism for this practical infrared material.

Temperature-Dependent Refractive Index Measurements of L-BBH2 Glass for the Subaru CHARIS Integral Field Spectrograph

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.; Miller, Kevin H.; Quijada, Manuel A.; Groff, Tyler D.

2015-01-01

Using the Cryogenic High Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, we have made the first cryogenic measurements of absolute refractive index for Ohara L-BBH2 glass to enable the design of a prism for the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) at the Subaru telescope. L-BBH2 is employed in CHARIS's prism design for improving the spectrograph's dispersion uniformity. Index measurements were made at temperatures from 110 to 305 K at wavelengths from 0.46 to 3.16 micron. We report absolute refractive index (n), dispersion (dn/d(lambda), and thermo-optic coefficient (dn/dT) for this material along with estimated single measurement uncertainties as a function of wavelength and temperature. We provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures within applicable ranges. This paper also speaks of the challenges in measuring index for a material which is not available in sufficient thickness to fabricate a typical prism for measurement in CHARMS, the tailoring of the index prism design that allowed these index measurements to be made, and the remarkable results obtained from that prism for this practical infrared material.

Technology perspectives in the future exploration of extreme environments

NASA Astrophysics Data System (ADS)

Cutts, J.; Balint, T.; Kolawa, El.; Peterson, C.

2007-08-01

Solar System exploration is driven by high priority science goals and objectives at diverse destinations, as described in the NRC Decadal Survey and in NASA's 2006 Solar System Exploration (SSE) Roadmap. Proposed missions to these targets encounter extreme environments, including high or low temperatures, high pressure, corrosion, high heat flux, radiation and thermal cycling. These conditions are often coupled, such as low temperature and high radiation at Europa; and high temperature and high pressure near the surface of Venus. Mitigation of these environmental conditions frequently reaches beyond technologies developed for terrestrial applications, for example, by the automotive and oil industries. Therefore, space agencies require dedicated technology developments to enable these future missions. Within NASA, proposed missions are divided into three categories. Competed small (Discovery class) and medium (New Frontiers class) missions are cost capped, thus limiting significant technology developments. Therefore, large (Flagship class) missions are required not only to tackle key science questions which can't be addressed by smaller missions, but also to develop mission enabling technologies that can feed forward to smaller missions as well. In a newly completed extreme environment technology assessment at NASA, we evaluated technologies from the current State of Practice (SoP) to advanced concepts for proposed missions over the next decades. Highlights of this report are discussed here, including systems architectures, such as hybrid systems; protection systems; high temperature electronics; power generation and storage; mobility technologies; sample acquisition and mechanisms; and the need to test these technologies in relevant environments. It is expected that the findings - documented in detail in NASA's Extreme Environments Technologies report - would help identifying future technology investment areas, and in turn enable or enhance planned SSE missions, while reducing mission cost and risk.

[Joint effects of water temperature and salinity on the expression of gill Hsp70 gene in Pinctada martensii (Dunker)].

PubMed

Wang, Ya-Nan; Wang, Hui; Zhu, Xiao-Wen; Luo, Ming-Ming; Liu, Zhi-Gang; Du, Xiao-Dong

2012-12-01

By using central composite experimental design and response surface method, the joint effects of water temperature (16-40 degrees C) and salinity (10-50) on the expression of gill Hsp70 gene in Pinctada martensii (Dunker) were studied under laboratory conditions. The results showed that the linear and quadratic effects of temperature on the expression of gill Hsp70 gene were significant, the linear effect of salinity was not significant, while the quadratic effect of salinity was significant. The interactive effect of temperature and salinity was not significant, and the effect of temperature was greater than that of salinity. The model equation of the gill Hsp70 gene expression was established, with the R2, Adj. R2, and Pred. R2 as high as 98.7%, 97.4%, and 89.2%, respectively, suggesting that the overarching predictive capability of the model was very satisfactory, and could be practicably applied for prediction. Through the optimization of the model, the expression of the gill Hsp70 gene reached its minimum (0.5276) when the temperature was 26.78 degrees C and the salinity was 29.33, with the desirability value being 98%. These experimental results could offer theoretical reference for the high expression of gill Hsp70 gene in P. martensii, the maintenance of cell internal environment stability, and the enhancement of P. martensii stress resistance.

Causes of spring vegetation greenness trends in the northern mid-high latitudes from 1982 to 2004

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

Mao, Jiafu; Shi, Xiaoying; Thornton, Peter E

2012-01-01

The Community Land Model version 4 (CLM4) is applied to explore the spatial temporal patterns of spring (April May) vegetation growth trends over the northern mid high latitudes (NMH) (>25 N) between 1982 and 2004. During the spring season through the 23 yr period, both the satellite-derived and simulated normalized difference vegetation index (NDVI) anomalies show a statistically significant correlation and an overall greening trend within the study area. Consistently with the observed NDVI temperature relation, the CLM4 NDVI shows a significant positive association with the spring temperature anomaly for the NMH, North America and Eurasia. Large study areas experiencemore » temperature discontinuity associated with contrasting NDVI trends. Before and after the turning point (TP) of the temperature trends, climatic variability plays a dominant role, while the other environmental factors exert minor effects on the NDVI tendencies. Simulated vegetation growth is broadly stimulated by the increasing atmospheric CO2. Trends show that nitrogen deposition increases NDVI mostly in southeastern China, and decreases NDVI mainly in western Russia after the temperature TP. Furthermore, land use-induced NDVI trends vary roughly with the respective changes in land management practices (crop areas and forest coverage). Our results highlight how non-climatic factors mitigate or exacerbate the impact of temperature on spring vegetation growth, particularly across regions with intensive human activity.« less

Best Practices for Continuous Monitoring of Temperature and Flow in Wadeable Streams (External Review Draft)

EPA Science Inventory

This external review draft report is a technical "best practices" document describing sensor deployment for and data collection of continuous temperature and flow at ungaged sites in wadeable streams. This document addresses questions related to equipment needs; configuration, pl...

Characterization technique for inhomogeneous 4H-SiC Schottky contacts: A practical model for high temperature behavior

NASA Astrophysics Data System (ADS)

Brezeanu, G.; Pristavu, G.; Draghici, F.; Badila, M.; Pascu, R.

2017-08-01

In this paper, a characterization technique for 4H-SiC Schottky diodes with varying levels of metal-semiconductor contact inhomogeneity is proposed. A macro-model, suitable for high-temperature evaluation of SiC Schottky contacts, with discrete barrier height non-uniformity, is introduced in order to determine the temperature interval and bias domain where electrical behavior of the devices can be described by the thermionic emission theory (has a quasi-ideal performance). A minimal set of parameters, the effective barrier height and peff, the non-uniformity factor, is associated. Model-extracted parameters are discussed in comparison with literature-reported results based on existing inhomogeneity approaches, in terms of complexity and physical relevance. Special consideration was given to models based on a Gaussian distribution of barrier heights on the contact surface. The proposed methodology is validated by electrical characterization of nickel silicide Schottky contacts on silicon carbide (4H-SiC), where a discrete barrier distribution can be considered. The same method is applied to inhomogeneous Pt/4H-SiC contacts. The forward characteristics measured at different temperatures are accurately reproduced using this inhomogeneous barrier model. A quasi-ideal behavior is identified for intervals spanning 200 °C for all measured Schottky samples, with Ni and Pt contact metals. A predictable exponential current-voltage variation over at least 2 orders of magnitude is also proven, with a stable barrier height and effective area for temperatures up to 400 °C. This application-oriented characterization technique is confirmed by using model parameters to fit a SiC-Schottky high temperature sensor's response.

Synthetic nanocomposite MgH2/5 wt. % TiMn2 powders for solid-hydrogen storage tank integrated with PEM fuel cell.

PubMed

El-Eskandarany, M Sherif; Shaban, Ehab; Aldakheel, Fahad; Alkandary, Abdullah; Behbehani, Montaha; Al-Saidi, M

2017-10-16

Storing hydrogen gas into cylinders under high pressure of 350 bar is not safe and still needs many intensive studies dedic ated for tank's manufacturing. Liquid hydrogen faces also severe practical difficulties due to its very low density, leading to larger fuel tanks three times larger than traditional gasoline tank. Moreover, converting hydrogen gas into liquid phase is not an economic process since it consumes high energy needed to cool down the gas temperature to -252.8 °C. One practical solution is storing hydrogen gas in metal lattice such as Mg powder and its nanocomposites in the form of MgH 2 . There are two major issues should be solved first. One related to MgH 2 in which its inherent poor hydrogenation/dehydrogenation kinetics and high thermal stability must be improved. Secondly, related to providing a safe tank. Here we have succeeded to prepare a new binary system of MgH 2 /5 wt. % TiMn 2 nanocomposite powder that show excellent hydrogenation/dehydrogenation behavior at relatively low temperature (250 °C) with long cycle-life-time (1400 h). Moreover, a simple hydrogen storage tank filled with our synthetic nanocomposite powders was designed and tested in electrical charging a battery of a cell phone device at 180 °C through a commercial fuel cell.

Ultra-low power operation of self-heated, suspended carbon nanotube gas sensors

NASA Astrophysics Data System (ADS)

Chikkadi, Kiran; Muoth, Matthias; Maiwald, Verena; Roman, Cosmin; Hierold, Christofer

2013-11-01

We present a suspended carbon nanotube gas sensor that senses NO2 at ambient temperature and recovers from gas exposure at an extremely low power of 2.9 μW by exploiting the self-heating effect for accelerated gas desorption. The recovery time of 10 min is two orders of magnitude faster than non-heated recovery at ambient temperature. This overcomes an important bottleneck for the practical application of carbon nanotube gas sensors. Furthermore, the method is easy to implement in sensor systems and requires no additional components, paving the way for ultra-low power, compact, and highly sensitive gas sensors.

Study on Heat Transfer Agent Models of Transmission Line and Transformer

NASA Astrophysics Data System (ADS)

Wang, B.; Zhang, P. P.

2018-04-01

When using heat transfer simulation to study the dynamic overload of transmission line and transformer, it needs to establish the mathematical expression of heat transfer. However, the formula is a nonlinear differential equation or equation set and it is not easy to get general solutions. Aiming at this problem, some different temperature change processes caused by different initial conditions are calculated by differential equation and equation set. New agent models are developed according to the characteristics of different temperature change processes. The results show that the agent models have high precision and can solve the problem that the original equation cannot be directly applied in some practical engineers.

Association between high temperature and work-related injuries in Adelaide, South Australia, 2001-2010.

PubMed

Xiang, Jianjun; Bi, Peng; Pisaniello, Dino; Hansen, Alana; Sullivan, Thomas

2014-04-01

(1) To investigate the association between temperature and work-related injuries and (2) to identify groups of workers at high risk of work-related injuries in hot environments in Adelaide, South Australia. Workers' compensation claims in Adelaide, South Australia for 2001-2010 were used. The relationship between temperature and daily injury claims was estimated using a generalised estimating equation model. A piecewise linear spline function was used to quantify the effect of temperature on injury claims below and above thresholds. Overall, a 1°C increase in maximum temperature between 14.2°C and 37.7°C was associated with a 0.2% increase in daily injury claims. Specifically, the incidence rate ratios (IRRs) for male workers and young workers aged ≤24 were (1.004, 95% CI 1.002 to 1.006) and (1.005, 95% CI 1.002 to 1.008), respectively. Significant associations were also found for labourers (IRR 1.005, 95% CI 1.001 to 1.010), intermediate production and transport workers (IRR 1.003, 95% CI 1.001 to 1.005) and tradespersons (IRR 1.002, 95% CI 1.001 to 1.005). Industries at risk were agriculture, forestry and fishing (IRR 1.007, 95% CI 1.001 to 1.013), construction (IRR 1.006, 95% CI 1.002 to 1.011), and electricity, gas and water (IRR 1.029, 95% CI 1.002 to 1.058). There is a significant association between injury claims and temperature in Adelaide, South Australia, for certain industries and groups. Relevant adaptation and prevention measures are required at both policy and practice levels to address occupational exposure to high temperatures.

USSR Report, Agriculture.

DTIC Science & Technology

1984-05-03

interest. It demonstrates the possibility of developing vital varieties with a high degree of effectiveness of seed -farming selections according to the...the winter period in practically all zones of the republic there were sharp changes in temperature , which meant that plants either began to grow or...curtailed vegetation. Such overwintering had a negative effect on plants-they grew and developed slowly. However, as a result of the use of

Time-Temperature Profiling of United Kingdom Consumers' Domestic Refrigerators.

PubMed

Evans, Ellen W; Redmond, Elizabeth C

2016-12-01

Increased consumer demand for convenience and ready-to-eat food, along with changes to consumer food purchase and storage practices, have resulted in an increased reliance on refrigeration to maximize food safety. Previous research suggests that many domestic refrigerators operate at temperatures exceeding recommendations; however, the results of several studies were determined by means of one temperature data point, which, given temperature fluctuation, may not be a true indicator of actual continual operating temperatures. Data detailing actual operating temperatures and the effects of consumer practices on temperatures are limited. This study has collated the time-temperature profiles of domestic refrigerators in consumer kitchens (n = 43) over 6.5 days with concurrent self-reported refrigerator usage. Overall, the findings established a significant difference (P < 0.05) between one-off temperature (the recording of one temperature data point) and mean operating temperature. No refrigerator operated at ≤5.0°C for the entire duration of the study. Mean temperatures exceeding 5.0°C were recorded in the majority (91%) of refrigerators. No significant associations or differences were determined for temperature profiles and demographics, including household size, or refrigerator characteristics (age, type, loading, and location). A positive correlation (P < 0.05) between room temperature and refrigerator temperature was determined. Reported door opening frequency correlated with temperature fluctuation (P < 0.05). Thermometer usage was determined to be infrequent. Cumulatively, research findings have established that the majority of domestic refrigerators in consumer homes operate at potentially unsafe temperatures and that this is influenced by consumer usage. The findings from this study may be utilized to inform the development of shelf-life testing based on realistic domestic storage conditions. Furthermore, the data can inform the development of future educational interventions to increase safe domestic refrigeration practices.

Caustic Singularities Of High-Gain, Dual-Shaped Reflectors

NASA Technical Reports Server (NTRS)

Galindo, Victor; Veruttipong, Thavath W.; Imbriale, William A.; Rengarajan, Sambiam

1991-01-01

Report presents study of some sources of error in analysis, by geometric theory of diffraction (GTD), of performance of high-gain, dual-shaped antenna reflector. Study probes into underlying analytic causes of singularity, with view toward devising and testing practical methods to avoid problems caused by singularity. Hybrid physical optics (PO) approach used to study near-field spillover or noise-temperature characteristics of high-gain relector antenna efficiently and accurately. Report illustrates this approach and underlying principles by presenting numerical results, for both offset and symmetrical reflector systems, computed by GTD, PO, and PO/GO methods.

Applications using high-Tc superconducting terahertz emitters

PubMed Central

Nakade, Kurama; Kashiwagi, Takanari; Saiwai, Yoshihiko; Minami, Hidetoshi; Yamamoto, Takashi; Klemm, Richard A.; Kadowaki, Kazuo

2016-01-01

Using recently-developed THz emitters constructed from single crystals of the high-Tc superconductor Bi2Sr2CaCu2O8+δ, we performed three prototype tests of the devices to demonstrate their unique characteristic properties for various practical applications. The first is a compact and simple transmission type of THz imaging system using a Stirling cryocooler. The second is a high-resolution Michelson interferometer used as a phase-sensitive reflection-type imaging system. The third is a system with precise temperature control to measure the liquid absorption coefficient. The detailed characteristics of these systems are discussed. PMID:26983905

Warming and Inhibition of Salinization at the Ocean's Surface by Cyanobacteria

NASA Astrophysics Data System (ADS)

Wurl, O.; Bird, K.; Cunliffe, M.; Landing, W. M.; Miller, U.; Mustaffa, N. I. H.; Ribas-Ribas, M.; Witte, C.; Zappa, C. J.

2018-05-01

This paper describes high-resolution in situ observations of temperature and, for the first time, of salinity in the uppermost skin layer of the ocean, including the influence of large surface blooms of cyanobacteria on those skin properties. In the presence of the blooms, large anomalies of skin temperature and salinity of 0.95°C and -0.49 practical salinity unit were found, but a substantially cooler (-0.22°C) and saltier skin layer (0.19 practical salinity unit) was found in the absence of surface blooms. The results suggest that biologically controlled warming and inhibition of salinization of the ocean's surface occur. Less saline skin layers form during precipitation, but our observations also show that surface blooms of Trichodesmium sp. inhibit evaporation decreasing the salinity at the ocean's surface. This study has important implications in the assessment of precipitation over the ocean using remotely sensed salinity, but also for a better understanding of heat exchange and the hydrologic cycle on a regional scale.

Lowering the synthesis temperature of Y3Fe5O12 by surfactant assisted solid state reaction

NASA Astrophysics Data System (ADS)

Xue, Fenghua; Huang, Ju; Li, Tianrui; Wang, Zifan; Zhou, Xiaochao; Wei, Lujun; Gao, Baizhi; Zhai, Ya; Li, Qi; Xu, Qingyu; Du, Jun

2018-01-01

There is an urgent technical requirement of lowering the sintering temperature of Y3Fe5O12 (YIG) for its practical applications. In this paper, a modified solid state reaction method is reported by adding the surfactant of cetyltrimethylammonium bromide (CTAB). A high sintering temperature of 1200 °C is required for the formation of YIG phase without adding CTAB, which is effectively decreased to 1050 °C by adding CTAB. The morphology studies show that the sintering temperature plays the main role in the crystal growth and excludes the possible contribution of CTAB. The prepared YIG ceramic samples show soft ferromagnetic properties, with coercivity of only 21.2 Oe for the sample prepared with CTAB at 1050 °C, which decreases with increasing sintering temperature. The main role of adding CTAB is preventing the agglomeration of ball milled ultrafine source particles, which may facilitate the interdiffusion among them and promote the reaction at lower temperatures. Furthermore, the Gilbert damping constant is significantly reduced for YIG prepared by adding CTAB, which is one order smaller than that without CTAB.

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air.

PubMed

Beyer, Hannes; Wagner, Tino; Stemmer, Andreas

2016-01-01

Frequency-modulation atomic force microscopy has turned into a well-established method to obtain atomic resolution on flat surfaces, but is often limited to ultra-high vacuum conditions and cryogenic temperatures. Measurements under ambient conditions are influenced by variations of the dew point and thin water layers present on practically every surface, complicating stable imaging with high resolution. We demonstrate high-resolution imaging in air using a length-extension resonator operating at small amplitudes. An additional slow feedback compensates for changes in the free resonance frequency, allowing stable imaging over a long period of time with changing environmental conditions.

Information retrieval from holographic interferograms: Fundamentals and problems

NASA Technical Reports Server (NTRS)

Vest, Charles M.

1987-01-01

Holographic interferograms can contain large amounts of information about flow and temperature fields. Their information content can be very high because they can be viewed from many different directions. This multidirectionality, and fringe localization add to the information contained in the fringe pattern if diffuse illumination is used. Additional information, and increased accuracy can be obtained through the use of dual reference wave holography to add reference fringes or to effect discrete phase shift or hetrodyne interferometry. Automated analysis of fringes is possible if interferograms are of simple structure and good quality. However, in practice a large number of practical problems can arise, so that a difficult image processing task results.

Practical Aerobic Oxidations of Alcohols and Amines with Homogeneous Cu/TEMPO and Related Catalyst Systems

PubMed Central

Ryland, Bradford L.; Stahl, Shannon S.

2014-01-01

Alcohol and amine oxidations are common reactions in laboratory and industrial synthesis of organic molecules. Aerobic oxidation methods have long been sought for these transformations, but few practical methods exist that offer advantages over traditional oxidation methods. Recently developed homogeneous Cu/TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidinyl-N-oxyl) and related catalyst systems appear to fill this void. The reactions exhibit high levels of chemoselectivity and broad functional-group tolerance, and they often operate efficiently at room temperature with ambient air as the oxidant. These advances, together with their historical context and recent applications, are highlighted in this minireview. PMID:25044821

Comparing historical and modern methods of Sea Surface Temperature measurement - Part 1: Review of methods, field comparisons and dataset adjustments

NASA Astrophysics Data System (ADS)

Matthews, J. B. R.

2012-09-01

Sea Surface Temperature (SST) measurements have been obtained from a variety of different platforms, instruments and depths over the post-industrial period. Today most measurements come from ships, moored and drifting buoys and satellites. Shipboard methods include temperature measurement of seawater sampled by bucket and in engine cooling water intakes. Engine intake temperatures are generally thought to average a few tenths of a °C warmer than simultaneous bucket temperatures. Here I review SST measurement methods, studies comparing shipboard methods by field experiment and adjustments applied to SST datasets to account for variable methods. In opposition to contemporary thinking, I find average bucket-intake temperature differences reported from field studies inconclusive. Non-zero average differences often have associated standard deviations that are several times larger than the averages themselves. Further, average differences have been found to vary widely between ships and between cruises on the same ship. The cause of non-zero average differences is typically unclear given the general absence of additional temperature observations to those from buckets and engine intakes. Shipboard measurements appear of variable quality, highly dependent upon the accuracy and precision of the thermometer used and the care of the observer where manually read. Methods are generally poorly documented, with written instructions not necessarily reflecting actual practices of merchant mariners. Measurements cannot be expected to be of high quality where obtained by untrained sailors using thermometers of low accuracy and precision.

A clinical audit cycle of post-operative hypothermia in dogs.

PubMed

Rose, N; Kwong, G P S; Pang, D S J

2016-09-01

Use of clinical audits to assess and improve perioperative hypothermia management in client-owned dogs. Two clinical audits were performed. In Audit 1 data were collected to determine the incidence and duration of perioperative hypothermia (defined as rectal temperatures <37·0°C). The results from Audit 1 were used to reach consensus on changes to be implemented to improve temperature management, including re-defining hypothermia as rectal temperature <37·5°C. Audit 2 was performed after 1 month with changes in place. Audit 1 revealed a high incidence of post-operative hypothermia (88·0%) and prolonged time periods (7·5 hours) to reach normothermia. Consensus changes were to use a forced air warmer on all dogs and measure rectal temperatures hourly post-operatively until temperature ≥37·5°C. After 1 month with the implemented changes, Audit 2 identified a significant reduction in the time to achieve a rectal temperature of ≥37·5°C, with 75% of dogs achieving this goal by 3·5 hours. The incidence of hypothermia at tracheal extubation remained high in Audit 2 (97·3% with a rectal temperature <37·5°C). Post-operative hypothermia was improved through simple changes in practice, showing that clinical audit is a useful tool for monitoring post-operative hypothermia and improving patient care. Overall management of perioperative hypothermia could be further improved with earlier intervention. © 2016 British Small Animal Veterinary Association.

Estimations of temperature deviations in chromatographic columns using isenthalpic plots. I. Theory for isocratic systems.

PubMed

Tarafder, Abhijit; Iraneta, Pamela; Guiochon, Georges; Kaczmarski, Krzysztof; Poe, Donald P

2014-10-31

We propose to use constant enthalpy or isenthalpic diagrams as a tool to estimate the extent of the temperature variations caused by the mobile phase pressure drop along a chromatographic column, e.g. of its cooling in supercritical fluid and its heating in ultra-performance liquid chromatography. Temperature strongly affects chromatographic phenomena. Any of its variations inside the column, whether intended or not, can lead to significant changes in separation performance. Although instruments use column ovens in order to keep constant the column temperature, operating conditions leading to a high pressure drop may cause significant variations of the column temperature, both in the axial and the radial directions, from the set value. Different ways of measuring these temperature variations are available but they are too inconvenient to be employed in many practical situations. In contrast, the thermodynamic plot-based method that we describe here can easily be used with only a ruler and a pencil. They should be helpful in developing methods or in analyzing results in analytical laboratories. Although the most effective application area for this approach should be SFC (supercritical fluid chromatography), it can be applied to any chromatographic conditions in which temperature variations take place along the column due to the pressure drop, e.g. in ultra-high pressure liquid chromatography (UHPLC). The method proposed here is applicable to isocractic conditions only. Copyright © 2014 Elsevier B.V. All rights reserved.

Practical considerations for coil-wrapped Distributed Temperature Sensing setups

NASA Astrophysics Data System (ADS)

Solcerova, Anna; van Emmerik, Tim; Hilgersom, Koen; van de Giesen, Nick

2015-04-01

Fiber-optic Distributed Temperature Sensing (DTS) has been applied widely in hydrological and meteorological systems. For example, DTS has been used to measure streamflow, groundwater, soil moisture and temperature, air temperature, and lake energy fluxes. Many of these applications require a spatial monitoring resolution smaller than the minimum resolution of the DTS device. Therefore, measuring with these resolutions requires a custom made setup. To obtain both high temporal and high spatial resolution temperature measurements, fiber-optic cable is often wrapped around, and glued to, a coil, for example a PVC conduit. For these setups, it is often assumed that the construction characteristics (e.g., the coil material, shape, diameter) do not influence the DTS temperature measurements significantly. This study compares DTS datasets obtained during four measurement campaigns. The datasets were acquired using different setups, allowing to investigate the influence of the construction characteristics on the monitoring results. This comparative study suggests that the construction material, shape, diameter, and way of attachment can have a significant influence on the results. We present a qualitative and quantitative approximation of errors introduced through the selection of the construction, e.g., choice of coil material, influence of solar radiation, coil diameter, and cable attachment method. Our aim is to provide insight in factors that influence DTS measurements, which designers of future DTS measurements setups can take into account. Moreover, we present a number of solutions to minimize these errors for improved temperature retrieval using DTS.

A gold nanocluster-based fluorescent probe for simultaneous pH and temperature sensing and its application to cellular imaging and logic gates

NASA Astrophysics Data System (ADS)

Wu, Yun-Tse; Shanmugam, Chandirasekar; Tseng, Wei-Bin; Hiseh, Ming-Mu; Tseng, Wei-Lung

2016-05-01

Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated.Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr02341j

Selection of High Temperature Organic Materials for Future Stirling Convertors

NASA Technical Reports Server (NTRS)

Shin, Euy-Sik Eugene

2017-01-01

In the future higher temperature Stirling convertors for improved efficiency and performance, various high temperature organic materials have been demanded as essential components for their unique properties and functions such as bonding, potting, sealing, thread locking, insulation, and lubrication. The higher temperature capabilities would also allow current state-of-the-art (SOA) convertors to be used in additional missions, particularly those that require a Venus flyby for a gravity assist. Stirling convertor radioisotope generators have been developed for potential future space applications including Lunar/Mars surface power or a variety of spacecraft and vehicles, especially with a long mission cycle, sometimes up to 17 years, such as deep space exploration. Thus, performance, durability, and reliability of the organics should be critically evaluated in terms of comprehensive structure-process-service environment relations based on the potential mission specifications. The initial efforts in screening the high temperature candidates focused on the most susceptible organics, such as adhesive, potting compound, o-ring, shrink tubing, and thread locker materials in conjunction with commercially available materials. More systematic and practical test methodologies that were developed and optimized based on the extensive organic evaluations and validations performed for various Stirling convertor types were employed to determine thermal stability, outgassing, and material compatibility of the selected organic candidates against their functional requirements. Processing and fabrication conditions and procedures were also optimized. This paper presents results of the three-step candidate evaluation processes, their application limitations, and the final selection recommendations.

Creating a lab to facilitate high school student engagement in authentic paleoclimate science practices

NASA Astrophysics Data System (ADS)

Maloney, A.; Walsh, E.

2012-12-01

A solid understanding of timescales is crucial for any climate change discussion. This hands-on lab was designed as part of a dual-credit climate change course in which high school students can receive college credit. Using homemade ice cores, students have the opportunity to participate in scientific practices associated with collecting, processing, and interpreting temperature and CO2 data. Exploring millennial-scale cycles in ice core data and extending the CO2 record to the present allows students to discover timescales from an investigators perspective. The Ice Core Lab has been piloted in two high school classrooms and student engagement, and epistemological and conceptual understanding was evaluated using quantitative pre and post assessment surveys. The process of creating this lab involved a partnership between an education assessment professional, high school teachers, and University of Washington professors and graduate students in Oceanography, Earth and Space Sciences, Atmospheric Sciences and the Learning Sciences as part of the NASA Global Climate Change University of Washington in the High School program. This interdisciplinary collaboration led to the inception of the lab and was necessary to ensure that the lesson plan was pedagogically appropriate and scientifically accurate. The lab fits into a unit about natural variability and is paired with additional hands-on activities created by other graduate students that explore short-timescale temperature variations, Milankovitch cycles, isotopes, and other proxies. While the Ice Core Lab is intended to follow units that review the scientific process, global energy budget, and transport, it can be modified to fit any teaching platform.

Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.

PubMed

Cho, Jung Sang; Lee, Jeong-Cheol; Rhee, Sang-Hoon

2016-02-01

In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate. © 2015 Wiley Periodicals, Inc.

Low-Temperature Molten-Salt Production of Silicon Nanowires by the Electrochemical Reduction of CaSiO3.

PubMed

Dong, Yifan; Slade, Tyler; Stolt, Matthew J; Li, Linsen; Girard, Steven N; Mai, Liqiang; Jin, Song

2017-11-13

Silicon is an extremely important technological material, but its current industrial production by the carbothermic reduction of SiO 2 is energy intensive and generates CO 2 emissions. Herein, we developed a more sustainable method to produce silicon nanowires (Si NWs) in bulk quantities through the direct electrochemical reduction of CaSiO 3 , an abundant and inexpensive Si source soluble in molten salts, at a low temperature of 650 °C by using low-melting-point ternary molten salts CaCl 2 -MgCl 2 -NaCl, which still retains high CaSiO 3 solubility, and a supporting electrolyte of CaO, which facilitates the transport of O 2- anions, drastically improves the reaction kinetics, and enables the electrolysis at low temperatures. The Si nanowire product can be used as high-capacity Li-ion battery anode materials with excellent cycling performance. This environmentally friendly strategy for the practical production of Si at lower temperatures can be applied to other molten salt systems and is also promising for waste glass and coal ash recycling. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2

NASA Astrophysics Data System (ADS)

Loiko, P.; Yoon, S. J.; Serres, J. M.; Mateos, X.; Beecher, S. J.; Birch, R. B.; Savitski, V. G.; Kemp, A. J.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.; Mackenzie, J. I.

2016-08-01

High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77-450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated.

Evaluation of Fe-containing Li2CuO2 on CO2 capture performed at different physicochemical conditions.

PubMed

Yañez-Aulestia, Ana; Ovalle-Encinia, Oscar; Pfeiffer, Heriberto

2018-06-05

Li 2 CuO 2 and different iron-containing Li 2 CuO 2 samples were synthesized by solid state reaction. On iron-containing samples, atomic sites of copper are substituted by iron ions in the lattice (XRD and Rietveld analyses). Iron addition induces copper release from Li 2 CuO 2 , which produce cationic vacancies and CuO, due to copper (Cu 2+ ) and iron (Fe 3+ ) valence differences. Two different physicochemical conditions were used for analyzing CO 2 capture on these samples; (i) high temperature and (ii) low temperature in presence of water vapor. At high temperatures, iron addition increased CO 2 chemisorption, due to structural and chemical variations on Li 2 CuO 2 . Kinetic analysis performed by first order reaction and Eyring models evidenced that iron addition on Li 2 CuO 2 induced a faster CO 2 chemisorption but a higher thermal dependence. Conversely, CO 2 chemisorption at low temperature in water vapor presence practically did not vary by iron addition, although hydration and hydroxylation processes were enhanced. Moreover, under these physicochemical conditions the whole sorption process became slower on iron-containing samples, due to metal oxides presence.

Analyzing the Effects of Climate Factors on Soybean Protein, Oil Contents, and Composition by Extensive and High-Density Sampling in China.

PubMed

Song, Wenwen; Yang, Ruping; Wu, Tingting; Wu, Cunxiang; Sun, Shi; Zhang, Shouwei; Jiang, Bingjun; Tian, Shiyan; Liu, Xiaobing; Han, Tianfu

2016-05-25

From 2010 to 2013, 763 soybean samples were collected from an extensive area of China. The correlations between seed compositions and climate data were analyzed. The contents of crude protein and water-soluble protein, total amount of protein plus oil, and most of the amino acids were positively correlated with an accumulated temperature ≥15 °C (AT15) and the mean daily temperature (MDT) but were negatively correlated with hours of sunshine (HS) and diurnal temperature range (DTR). The correlations of crude oil and most fatty acids with climate factors were opposite to those of crude protein. Crude oil content had a quadratic regression relationship with MDT, and a positive correlation between oil content and MDT was found when the daily temperature was <19.7 °C. A path analysis indicated that DTR was the main factor that directly affected soybean protein and oil contents. The study illustrated the effects of climate factors on soybean protein and oil contents and proposed agronomic practices for improving soybean quality in different regions of China. The results provide a foundation for the regionalization of high-quality soybean production in China and similar regions in the world.

Efficient p-n junction-based thermoelectric generator that can operate at extreme temperature conditions

NASA Astrophysics Data System (ADS)

Chavez, Ruben; Angst, Sebastian; Hall, Joseph; Maculewicz, Franziska; Stoetzel, Julia; Wiggers, Hartmut; Thanh Hung, Le; Van Nong, Ngo; Pryds, Nini; Span, Gerhard; Wolf, Dietrich E.; Schmechel, Roland; Schierning, Gabi

2018-01-01

In many industrial processes, a large proportion of energy is lost in the form of heat. Thermoelectric generators can convert this waste heat into electricity by means of the Seebeck effect. However, the use of thermoelectric generators in practical applications on an industrial scale is limited in part because electrical, thermal, and mechanical bonding contacts between the semiconductor materials and the metal electrodes in current designs are not capable of withstanding thermal-mechanical stress and alloying of the metal-semiconductor interface when exposed to the high temperatures occurring in many real-world applications. Here we demonstrate a concept for thermoelectric generators that can address this issue by replacing the metallization and electrode bonding on the hot side of the device by a p-n junction between the two semiconductor materials, making the device robust against temperature induced failure. In our proof-of-principle demonstration, a p-n junction device made from nanocrystalline silicon is at least comparable in its efficiency and power output to conventional devices of the same material and fabrication process, but with the advantage of sustaining high hot side temperatures and oxidative atmosphere.

Strong light illumination on gain-switched semiconductor lasers helps the eavesdropper in practical quantum key distribution systems

NASA Astrophysics Data System (ADS)

Fei, Yang-yang; Meng, Xiang-dong; Gao, Ming; Yang, Yi; Wang, Hong; Ma, Zhi

2018-07-01

The temperature of the semiconductor diode increases under strong light illumination whether thermoelectric cooler is installed or not, which changes the output wavelength of the laser (Lee et al., 2017). However, other characteristics also vary as temperature increases. These variations may help the eavesdropper in practical quantum key distribution systems. We study the effects of temperature increase on gain-switched semiconductor lasers by simulating temperature dependent rate equations. The results show that temperature increase may cause large intensity fluctuation, decrease the output intensity and lead the signal state and decoy state distinguishable. We also propose a modified photon number splitting attack by exploiting the effects of temperature increase. Countermeasures are also proposed.

Agricultural practices altered soybean seed protein, oil, fatty acids, sugars, and minerals in the Midsouth USA.

PubMed

Bellaloui, Nacer; Bruns, H Arnold; Abbas, Hamed K; Mengistu, Alemu; Fisher, Daniel K; Reddy, Krishna N

2015-01-01

Information on the effects of management practices on soybean seed composition is scarce. Therefore, the objective of this research was to investigate the effects of planting date (PD) and seeding rate (SR) on seed composition (protein, oil, fatty acids, and sugars) and seed minerals (B, P, and Fe) in soybean grown in two row-types (RTs) on the Mississippi Delta region of the Midsouth USA. Two field experiments were conducted in 2009 and 2010 on Sharkey clay and Beulah fine sandy loam soil at Stoneville, MS, USA, under irrigated conditions. Soybean were grown in 102 cm single-rows and 25 cm twin-rows in 102 cm centers at SRs of 20, 30, 40, and 50 seeds m(-2). The results showed that in May and June planting, protein, glucose, P, and B concentrations increased with increased SR, but at the highest SRs (40 and 50 seeds m(-2)), the concentrations remained constant or declined. Palmitic, stearic, and linoleic acid concentrations were the least responsive to SR increases. Early planting resulted in higher oil, oleic acid, sucrose, B, and P on both single and twin-rows. Late planting resulted in higher protein and linolenic acid, but lower oleic acid and oil concentrations. The changes in seed constituents could be due to changes in environmental factors (drought and temperature), and nutrient accumulation in seeds and leaves. The increase of stachyose sugar in 2010 may be due to a drier year and high temperature in 2010 compared to 2009; suggesting the possible role of stachyose as an environmental stress compound. Our research demonstrated that PD, SR, and RT altered some seed constituents, but the level of alteration in each year dependent on environmental factors such as drought and temperature. This information benefits growers and breeders for considering agronomic practices to select for soybean seed nutritional qualities under drought and high heat conditions.

Isolation of Metals from Liquid Wastes: Reactive Scavenging in Turbulent Thermal Reactors

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

Jost O.L. Wendt; Alan R. Kerstein; Alexander Scheeline

2003-08-06

The Overall project demonstrated that toxic metals (cesium Cs and strontium Sr) in aqueous and organic wastes can be isolated from the environment through reaction with kaolinite based sorbent substrates in high temperature reactor environments. In addition, a state-of-the art laser diagnostic tool to measure droplet characteristic in practical 'dirty' laboratory environments was developed, and was featured on the cover of a recent edition of the scientific journal ''applied Spectroscopy''. Furthermore, great strides have been made in developing a theoretical model that has the potential to allow prediction of the position and life history of every particle of waste inmore » a high temperature, turbulent flow field, a very challenging problem involving as it does, the fundamentals of two phase turbulence and of particle drag physics.« less

Field emission properties of nano-structured cobalt ferrite (CoFe2O4) synthesized by low-temperature chemical method

NASA Astrophysics Data System (ADS)

Ansari, S. M.; Suryawanshi, S. R.; More, M. A.; Sen, Debasis; Kolekar, Y. D.; Ramana, C. V.

2018-06-01

We report on the field-emission properties of structure-morphology controlled nano-CoFe2O4 (CFO) synthesized via a simple and low-temperature chemical method. Structural analyses indicate that the spongy-CFO (approximately, 2.96 nm) is nano-structured, spherical, uniformly-distributed, cubic-structured and porous. Field emission studies reveal that CFO exhibit low turn-on field (4.27 V/μm) and high emission current-density (775 μA/cm2) at a lower applied electric field of 6.80 V/μm. In addition, extremely good emission current stability is obtained at a pre-set value of 1 μA and high emission spot-density over large area (2 × 2 cm2) suggesting the applicability of these materials for practical applications in vacuum micro-/nano-electronics.

Energy and Emission Characteristics of a Short-Arc Xenon Flash Lamp Under "Saturated" Optical Brightness Conditions

NASA Astrophysics Data System (ADS)

Kamrukov, A. S.; Kireev, S. G.; Kozlov, N. P.; Shashkovskii, S. G.

2017-09-01

We present the results of a study of the electrical, energy, and spectral brightness characteristics of an experimental three-electrode high-pressure xenon flash lamp under conditions ensuring close to maximum possible spectral brightness for the xenon emission. We show that under saturated optical brightness conditions (brightness temperature in the visible region of the spectrum 30,000 K), emission of a pulsed discharge in xenon is quite different from the emission from an ideal blackbody: the maximum brightness temperatures are 24,000 K in the short-wavelength UV region and 19,000 K in the near IR range. The relative fraction of UV radiation in the emission spectrum of the lamp is >50%, which lets us consider such lamps as promising broadband sources of radiation with high spectral brightness for many important practical applications.

Liquid crystal materials and tunable devices for optical communications

NASA Astrophysics Data System (ADS)

Du, Fang

In this dissertation, liquid crystal materials and devices are investigated in meeting the challenges for photonics and communications applications. The first part deals with polymer-stabilized liquid crystal (PSLC) materials and devices. Three polymer-stabilized liquid crystal systems are developed for optical communications. The second part reports the experimental investigation of a novel liquid-crystal-infiltrated photonic crystal fiber (PCF) and explores its applications in fiber-optic communications. The curing temperature is found to have significant effects on the PSLC performance. The electro-optic properties of nematic polymer network liquid crystal (PNLC) at different curing temperatures are investigated experimentally. At high curing temperature, a high contrast, low drive voltage, and small hysteresis PNLC is obtained as a result of the formed large LC microdomains. With the help of curing temperature effect, it is able to develop PNLC based optical devices with highly desirable performances for optical communications. Such high performance is generally considered difficult to realize for a PNLC. In fact, the poor performance of PNLC, especially at long wavelengths, has hindered it from practical applications for optical communications for a long time. Therefore, the optimal curing temperature effect discovered in this thesis would enable PSLCs for practical industrial applications. Further more, high birefringence LCs play an important role for near infrared photonic devices. The isothiocyanato tolane liquid crystals exhibit a high birefringence and low viscosity. The high birefringence LC dramatically improves the PSLC contrast ratio while keeping a low drive voltage and fast response time. A free-space optical device by PNLC is experimentally demonstrated and its properties characterized. Most LC devices are polarization sensitive. To overcome this drawback, we have investigated the polymer-stabilized cholesteric LC (PSCLC). Combining the curing temperature effect and high birefringence LC, a polarization independent fiber-optical device is realized with over 30 dB attenuation, ˜12 V rms drive voltage and 11/28 milliseconds (rise/decay) response times. A polymer-stabilized twisted nematic LC (PS TNLC) is also proposed as a variable optical attenuator for optical communications. By using the polarization control system, the device is polarization independent. The polymer network in a PS TNLC not only results in a fast response time (0.9/9 milliseconds for rise/decay respectively), but also removes the backflow effect of TNLC which occurs in the high voltage regime. Another major achievement in this thesis is the first demonstration of an electrically tunable LC-infiltrated photonic crystal fiber (PCF). Two different LC PCF configurations are studied. For the first time, electrically tunable LC PCFs are demonstrated experimentally. The guiding mechanism and polarization properties are studied. Preliminary experimental results are also given for the thermo-optical properties of a LC filled air-core PCF. In conclusion, this dissertation has solved important issues related to PSLC and enables its applications as VOAs and light shutters in optical communications. Through experimental investigations of the LC filled PCFs, a new possibility of developing tunable micro-sized fiber devices is opened for optical communications as well.

Numerical and experimental studies of particle flow in a high-pressure boundary-layer wind tunnel

NASA Technical Reports Server (NTRS)

White, B. R.

1984-01-01

The approach was to simulate the surface environment of Venus as closely as practicable and to conduct experiments to determine threshold wind speeds, particle flux, particle velocities, and the characteristics of various aeolian bedforms. The Venus Wind Tunnel (VWT) is described and the experimental procedures that were developed to make the high-pressure wind tunnel measurements are presented. In terrestrial simulations of aeolian activity, it is possible to conduct experiments under pressures and temperatures found in natural environments. Because of the high pressures and temperatures, Venusian simulations are difficult to achieve in this regard. Consequently, extrapolation of results to Venue potentially involves unknown factors. The experimental rationale was developed in the following way: The VWT enables the density of the Venusian atmosphere to be reproduced. Density is the principal atmospheric property for governing saltation threshold, particle flux, and the ballistics of airborne particles (equivalent density maintains dynamic similarity of gas flow). When operated at or near Earth's ambient temperature, VWT achieves Venusian atmospheric density at pressures of about 30 bar, or about one third less than those on Venus, although still maintaining dynamic similarity to Venus.

Self-Powered Wireless Smart Sensor Node Enabled by an Ultrastable, Highly Efficient, and Superhydrophobic-Surface-Based Triboelectric Nanogenerator.

PubMed

Zhao, Kun; Wang, Zhong Lin; Yang, Ya

2016-09-27

Wireless sensor networks will be responsible for a majority of the fast growth in intelligent systems in the next decade. However, most of the wireless smart sensor nodes require an external power source such as a Li-ion battery, where the labor cost and environmental waste issues of replacing batteries have largely limited the practical applications. Instead of using a Li-ion battery, we report an ultrastable, highly efficient, and superhydrophobic-surface-based triboelectric nanogenerator (TENG) to scavenge wind energy for sustainably powering a wireless smart temperature sensor node. There is no decrease in the output voltage and current of the TENG after continuous working for about 14 h at a wind speed of 12 m/s. Through a power management circuit, the TENG can deliver a constant output voltage of 3.3 V and a pulsed output current of about 100 mA to achieve highly efficient energy storage in a capacitor. A wireless smart temperature sensor node can be sustainably powered by the TENG for sending the real-time temperature data to an iPhone under a working distance of 26 m, demonstrating the feasibility of the self-powered wireless smart sensor networks.

Dilute Acid and Autohydrolysis Pretreatment

NASA Astrophysics Data System (ADS)

Yang, Bin; Wyman, Charles E.

Exposure of cellulosic biomass to temperatures of about 120-210°C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such “steam gun” devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems.

Some practical considerations for economical back contact formation on high efficiency solar cells

NASA Technical Reports Server (NTRS)

Lesk, I. A.

1985-01-01

The back contact can detract from solar cell performance in a number of ways: high recombination, barrier, photovoltaic, minority carrier collection, resistance. These effects may act in a nonuniform fashion over the cell area, and complicate the analysis of photovoltaic performance aimed at a better understanding of the effects of device geometry and material and/or processing parameters. The back contact is tested by reproducing it on both sides of a substrate. The objective is to find a back contact which performs well as a back contact, can be applied cheaply to large area solar cells, fits well into a practical process sequence, does not introduce structural damage or undesirable impurities into the silicon substrate, is compatible with an effective front contact technology, permits low temperature solder contacting, adheres well to silicon, and is reliable.

Probability-based classifications for spatially characterizing the water temperatures and discharge rates of hot springs in the Tatun Volcanic Region, Taiwan.

PubMed

Jang, Cheng-Shin

2015-05-01

Accurately classifying the spatial features of the water temperatures and discharge rates of hot springs is crucial for environmental resources use and management. This study spatially characterized classifications of the water temperatures and discharge rates of hot springs in the Tatun Volcanic Region of Northern Taiwan by using indicator kriging (IK). The water temperatures and discharge rates of the springs were first assigned to high, moderate, and low categories according to the two thresholds of the proposed spring classification criteria. IK was then used to model the occurrence probabilities of the water temperatures and discharge rates of the springs and probabilistically determine their categories. Finally, nine combinations were acquired from the probability-based classifications for the spatial features of the water temperatures and discharge rates of the springs. Moreover, various combinations of spring water features were examined according to seven subzones of spring use in the study region. The research results reveal that probability-based classifications using IK provide practicable insights related to propagating the uncertainty of classifications according to the spatial features of the water temperatures and discharge rates of the springs. The springs in the Beitou (BT), Xingyi Road (XYR), Zhongshanlou (ZSL), and Lengshuikeng (LSK) subzones are suitable for supplying tourism hotels with a sufficient quantity of spring water because they have high or moderate discharge rates. Furthermore, natural hot springs in riverbeds and valleys should be developed in the Dingbeitou (DBT), ZSL, Xiayoukeng (XYK), and Macao (MC) subzones because of low discharge rates and low or moderate water temperatures.

High carotenoids content can enhance resistance of selected Pinctada fucata families to high temperature stress.

PubMed

Meng, Zihao; Zhang, Bo; Liu, Baosuo; Li, Haimei; Fan, Sigang; Yu, Dahui

2017-02-01

Carotenoids are a class of natural antioxidants widely found in aquatic, and they have significant effects on the growth, survival, and immunity of these organisms. To investigate the mechanisms of carotenoids in high temperature resistance, we observed the immune response of selected pearl oyster Pinctada fucata (Akoya pearl oyster) families with different carotenoids contents to high temperature stress. The results indicated that the survival rate (SR) of P. fucata decreased significantly with increase in temperature from 26 °C to 34 °C and with the decrease of total carotenoids content (TCC); when the TCC was higher, the SR tended to be higher. TCC and total antioxidant capacity (TAC) decreased significantly at 30 °C with increasing stress time. Correlation analysis indicated that TAC was positively and linearly correlated with TCC, and SR was S-type correlated with TCC and TAC. Immune analysis indicated that levels of superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) in selected families (with higher TCC) under temperature stress (at 30 °C) were generally significantly lower than in the control group (with lowest TCC) and from 0 to 96 h, the levels of each of these substances varied significantly. Levels of SOD, CAT, and MDA within each family first rose from 0 to 3 h, then decreased to their lowest point after 24 h, and then rose again to their highest levels at 96 h. When TCC was higher, the levels of SOD, CAT, and MDA tended to be lower. These findings indicated that carotenoids play an important role in improving survival rates of P. fucata under high temperature stress by enhancing animals' antioxidant system, and could serve as an index for breeding stress-resistant lines in selective breeding practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

Global perspectives on ensuring the safety of pharmaceutical products in the distribution process
.

PubMed

Jeong, Sohyun; Ji, Eunhee

2018-01-01

The distribution of counterfeit or falsified drugs is increasing worldwide. This can contribute to the high burden of disease and cost to society and is of global concern with the worldwide circulation of pharmaceuticals. The preparation and implementation of good distribution practice should be one of the most important aspects of ensuring safe drug circulation and administration. This research aimed to compare and analyze good distribution practice guidelines from advanced countries and international organizations, and to evaluate the status of the current good distribution practice guidelines in the world. Advanced pharmaceutical countries and international organizations, such as the World Health Organization, European Union, Pharmaceutical Inspection Co-operation Scheme, United States of America, Canada, and Australia, which have stable good distribution practice guidelines and public confidence, were included in the analysis. The World Health Organization and European Union guidelines are models for standardized good distribution practice for nations worldwide. The United States of America has a combination of four different series of distribution practices which have a unique structure and detailed content compared to those of other countries. The Canadian guidelines focus on temperature control during storage and transportation. The Australian guidelines apply to both classes of medicinal products and medical devices and need separate standardization. Transparent information about the Internet chain, international cooperation regarding counterfeiting, a high-standard qualification of sellers and customers, and technology to track and trace the whole life cycle of drugs should be the main focus of future good distribution practice guidelines worldwide.
.

Small anisotropy, weak thermal fluctuations, and high field superconductivity in Co-doped iron pnictide Ba(Fe1-xCox)2As2

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

Yamamoto, A.; Jaroszynski, J.; Tarantini, C.

2009-01-01

We performed high-field magnetotransport and magnetization measurements on a single crystal of the 122-phase iron pnictide Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. Unlike the high-temperature superconductor cuprates and 1111-phase oxypnictides, Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} showed practically no broadening of the resistive transitions under magnetic fields up to 45 T. We report the temperature dependencies of the upper critical field H{sub c2} both parallel and perpendicular to the c-axis, the irreversibility field H{sub irr}{sup c}(T), and a rather unusual symmetric volume pinning force curve F{sub p}(H) suggestive of a strong pinning nanostructure. The anisotropy parameter {gamma} = H{sub c2}{sup ab}/H{sub c2}{supmore » c} deduced from the slopes of dH{sub c2}{sup ab}/dT = 4.9 T/K and dH{sub c2}{sup c}/dT = 2.5 T/K decreases from -2 near T{sub c}, to -1.5 at lower temperatures, much smaller than {gamma} for 1111 pnictides and high-T{sub c} cuprates.« less

Enhanced High-Temperature Cyclic Stability of Al-Doped Manganese Dioxide and Morphology Evolution Study Through in situ NMR under High Magnetic Field.

PubMed

Huang, Shenggen; Sun, Jian; Yan, Jian; Liu, Jiaqin; Wang, Weijie; Qin, Qingqing; Mao, Wenping; Xu, Wei; Wu, Yucheng; Wang, Junfeng

2018-03-21

In this work, Al-doped MnO 2 (Al-MO) nanoparticles have been synthesized by a simple chemical method with the aim to enhance cycling stability. At room temperature and 50 °C, the specific capacitances of Al-MO are well-maintained after 10 000 cycles. Compared with pure MnO 2 nanospheres (180.6 F g -1 at 1 A g -1 ), Al-MO also delivers an enhanced specific capacitance of 264.6 F g -1 at 1 A g -1 . During the cycling test, Al-MO exhibited relatively stable structure initially and transformed to needlelike structures finally both at room temperature and high temperature. In order to reveal the morphology evolution process, in situ NMR under high magnetic field has been carried out to probe the dynamics of structural properties. The 23 Na spectra and the SEM observation suggest that the morphology evolution may follow pulverization/reassembling process. The Na + intercalation/deintercalation induced pulverization, leading to the formation of tiny MnO 2 nanoparticles. After that, the pulverized tiny nanoparticles reassembled into new structures. In Al-MO electrodes, doping of Al 3+ could slow down this structure evolution process, resulting in a better electrochemical stability. This work deepens the understanding on the structural changes in faradic reaction of pseudocapacitive materials. It is also important for the practical applications of MnO 2 -based supercapacitors.

Food safety hazards lurk in the kitchens of young adults.

PubMed

Byrd-Bredbenner, Carol; Maurer, Jaclyn; Wheatley, Virginia; Cottone, Ellen; Clancy, Michele

2007-04-01

Food mishandling in home kitchens likely causes a significant amount of foodborne disease; however, little is known about the food safety hazards lurking in home kitchens. The purposes of this study were to audit the kitchens of young adults with education beyond high school to identify food safety problems and develop recommendations for education efforts. Researchers developed a criterion-referenced home kitchen observation instrument to assess compliance of home food storage and rotation practices (e.g., temperature), sanitation and chemical storage, and general kitchen condition (e.g., infestation) with recommended practices. The instrument contained seven scales: Kitchen Cleanliness (eight items), Appliance Cleanliness (three items), Cleaning Supplies Availability (eight items), Temperatures (Food Thermometer Access & Refrigerator/Freezer Temperatures) (five items), Cold Food Storage (seven items), Dry Food Storage (eight items), and Poisons Storage (two items). Descriptive statistics were conducted to describe the study population, as a whole, and by gender. A total of 154 young adults (mean age, 20.7+/- 1.3 SD) enrolled in a northeastern university participated. Participants scored 70% or higher on Poisons Storage, Dry Food Storage, Kitchen Cleanliness, and Cleaning Supplies Availability scales but less than 60% on the Appliance Cleanliness and Cold Food Storage scales. Performance was lowest on the Temperatures scale. Females scored significantly higher than males on the Kitchen Cleanliness and Cleaning Supply Availability scales. Average refrigerator and freezer temperatures were higher than recommendations. Food safety education targeted at this young adult population needs to evolve into focused messages pertaining to the key food safety violations in this population.

Effect of atomic layer deposition temperature on current conduction in Al2O3 films formed using H2O oxidant

NASA Astrophysics Data System (ADS)

Hiraiwa, Atsushi; Matsumura, Daisuke; Kawarada, Hiroshi

2016-08-01

To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al2O3 films is investigated based on the recently proposed space-charge-controlled field emission model. Leakage current measurement shows that Al2O3 metal-insulator-semiconductor capacitors formed on the Si substrates underperform thermally grown SiO2 capacitors at the same average field. However, using equivalent oxide field as a more practical measure, the Al2O3 capacitors are found to outperform the SiO2 capacitors in the cases where the capacitors are negatively biased and the gate material is adequately selected to reduce virtual dipoles at the gate/Al2O3 interface. The Al2O3 electron affinity increases with the increasing ALD temperature, but the gate-side virtual dipoles are not affected. Therefore, the leakage current of negatively biased Al2O3 capacitors is approximately independent of the ALD temperature because of the compensation of the opposite effects of increased electron affinity and permittivity in Al2O3. By contrast, the substrate-side sheet of charge increases with increasing ALD temperature above 210 °C and hence enhances the current of positively biased Al2O3 capacitors more significantly at high temperatures. Additionally, an anomalous oscillatory shift of the current-voltage characteristics with ALD temperature was observed in positively biased capacitors formed by low-temperature (≤210 °C) ALD. This shift is caused by dipoles at the Al2O3/underlying SiO2 interface. Although they have a minimal positive-bias leakage current, the low-temperature-grown Al2O3 films cause the so-called blisters problem when heated above 400 °C. Therefore, because of the absence of blistering, a 450 °C ALD process is presently the most promising technology for growing high-reliability Al2O3 films.

High temperature microelectrophoresis studies of the solid oxide/water interface

NASA Astrophysics Data System (ADS)

Fedkin, Mark Valentinovich

Metal oxides are abundant components of geo-environmental systems and are widely used materials in industry. Many practical applications of oxide materials require the knowledge of their surface properties at both ambient and elevated temperatures. Due to substantial technical challenges associated with experimental studies of solid/water interfaces at elevated temperatures, consistent data on adsorption, surface charge, and zeta potential for most oxide materials are limited to temperatures less than 100°C. A high temperature microelectrophoresis technique, developed in this study, made it possible to extend the zeta potential measurements at the solid oxide/water interface to 200°C. The design of the high temperature electrophoresis cell allowed for the visual microscopic observation of the electrophoretic movement of suspended particles through pressure-tight sapphire windows. The electrophoretic mobilities of metal oxide particles suspended in aqueous solutions were measured in a DC electric field as a function of pH, ionic strength, and temperature. The experimental procedure and methods for evaluation of the main experimental parameters (electrophoretic mobility, electric field strength, high temperature pH, and cell constant) have been developed. Zeta potentials were calculated from the experimental data using O'Brien and White's (1978) numerical solution for electrophoretic mobility equation. Zeta potentials and isoelectric points (IEP) of the metal oxide/aqueous solution interface were experimentally determined for ZrO2, TiO 2(rutile), and alphaAl2O3 at 25, 120, and 200°C. The background solutions used for the preparation of suspensions were pure H2O, NaCl(aq) (10-4--10-2 mol.kg-1), and SrCl2 (10-4 mol.kg, for TiO2). For all studied materials, the IEPs were found to regularly decrease with increasing temperature, which agrees with available theoretical predictions. Thermodynamic functions, including Gibbs energy, enthalpy, and heat capacity, were estimated for the H +/OH- adsorption from the experimental IEP data using the 1-pK model of the oxide/water interface. The experimental information obtained in this study combined with data from potentiometric titration and other experimental methods form the basis for future theoretical studies of the electrical double layer at the oxide/water interface.

High-performance silicon photonics technology for telecommunications applications.

PubMed

Yamada, Koji; Tsuchizawa, Tai; Nishi, Hidetaka; Kou, Rai; Hiraki, Tatsurou; Takeda, Kotaro; Fukuda, Hiroshi; Ishikawa, Yasuhiko; Wada, Kazumi; Yamamoto, Tsuyoshi

2014-04-01

By way of a brief review of Si photonics technology, we show that significant improvements in device performance are necessary for practical telecommunications applications. In order to improve device performance in Si photonics, we have developed a Si-Ge-silica monolithic integration platform, on which compact Si-Ge-based modulators/detectors and silica-based high-performance wavelength filters are monolithically integrated. The platform features low-temperature silica film deposition, which cannot damage Si-Ge-based active devices. Using this platform, we have developed various integrated photonic devices for broadband telecommunications applications.

High-performance silicon photonics technology for telecommunications applications

PubMed Central

Yamada, Koji; Tsuchizawa, Tai; Nishi, Hidetaka; Kou, Rai; Hiraki, Tatsurou; Takeda, Kotaro; Fukuda, Hiroshi; Ishikawa, Yasuhiko; Wada, Kazumi; Yamamoto, Tsuyoshi

2014-01-01

By way of a brief review of Si photonics technology, we show that significant improvements in device performance are necessary for practical telecommunications applications. In order to improve device performance in Si photonics, we have developed a Si-Ge-silica monolithic integration platform, on which compact Si-Ge–based modulators/detectors and silica-based high-performance wavelength filters are monolithically integrated. The platform features low-temperature silica film deposition, which cannot damage Si-Ge–based active devices. Using this platform, we have developed various integrated photonic devices for broadband telecommunications applications. PMID:27877659

High-performance silicon photonics technology for telecommunications applications

NASA Astrophysics Data System (ADS)

Yamada, Koji; Tsuchizawa, Tai; Nishi, Hidetaka; Kou, Rai; Hiraki, Tatsurou; Takeda, Kotaro; Fukuda, Hiroshi; Ishikawa, Yasuhiko; Wada, Kazumi; Yamamoto, Tsuyoshi

2014-04-01

By way of a brief review of Si photonics technology, we show that significant improvements in device performance are necessary for practical telecommunications applications. In order to improve device performance in Si photonics, we have developed a Si-Ge-silica monolithic integration platform, on which compact Si-Ge-based modulators/detectors and silica-based high-performance wavelength filters are monolithically integrated. The platform features low-temperature silica film deposition, which cannot damage Si-Ge-based active devices. Using this platform, we have developed various integrated photonic devices for broadband telecommunications applications.

Paper-based silver-nanowire electronic circuits with outstanding electrical conductivity and extreme bending stability.

PubMed

Huang, Gui-Wen; Xiao, Hong-Mei; Fu, Shao-Yun

2014-08-07

Here a facile, green and efficient printing-filtration-press (PFP) technique is reported for room-temperature (RT) mass-production of low-cost, environmentally friendly, high performance paper-based electronic circuits. The as-prepared silver nanowires (Ag-NWs) are uniformly deposited at RT on a pre-printed paper substrate to form high quality circuits via vacuum filtration and pressing. The PFP circuit exhibits more excellent electrical property and bending stability compared with other flexible circuits made by existing techniques. Furthermore, practical applications of the PFP circuits are demonstrated.

The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass--Temperature Management during Cardiopulmonary Bypass.

PubMed

Engelman, Richard; Baker, Robert A; Likosky, Donald S; Grigore, Alina; Dickinson, Timothy A; Shore-Lesserson, Linda; Hammon, John W

2015-09-01

To improve our understanding of the evidence-based literature supporting temperature management during adult cardiopulmonary bypass, The Society of Thoracic Surgeons, the Society of Cardiovascular Anesthesiology and the American Society of ExtraCorporeal Technology tasked the authors to conduct a review of the peer-reviewed literature, including 1) optimal site for temperature monitoring, 2) avoidance of hyperthermia, 3) peak cooling temperature gradient and cooling rate, and 4) peak warming temperature gradient and rewarming rate. Authors adopted the American College of Cardiology/American Heart Association method for development clinical practice guidelines, and arrived at the following recommendation.

Combustion of Metals in Reduced-Gravity and Extra Terrestrial Environments

NASA Technical Reports Server (NTRS)

Branch, M.C.; Abbud-Madrid, A.; Daily, J. W.

1999-01-01

The combustion of metals is a field with important practical applications in rocket propellants, high-temperature flames, and material synthesis. Also, the safe operation of metal containers in high-pressure oxygen systems and with cryogenic fuels and oxidizers remains an important concern in industry. The increasing use of metallic components in spacecraft and space structures has also raised concerns about their flammability properties and fire suppression mechanisms. In addition, recent efforts to embark on unmanned and manned planetary exploration, such as on Mars, have also renewed the interest in metal/carbon-dioxide combustion as an effective in situ resource utilization technology. In spite of these practical applications, the understanding of the combustion properties of metals remains far behind that of the most commonly used fuels such as hydrocarbons. The lack of understanding is due to the many problems unique to metal- oxidizer reactions such as: low-temperature surface oxidation prior to ignition, heterogeneous reactions, very high combustion temperatures, product condensation, high emissivity of products, and multi-phase interactions. Very few analytical models (all neglecting the influence of gravity) have been developed to predict the burning characteristics and the flame structure details. Several experimental studies attempting to validate these models have used small metal particles to recreate gravity-free conditions. The high emissivity of the flames, rapid reaction, and intermittent explosions experienced by these particles have made the gathering of any useful information on burning rates and flame structure very difficult. The use of a reduced gravity environment is needed to clarify some of the complex interactions among the phenomena described above. First, the elimination of the intrusive buoyant flows that plague all combustion phenomena is of paramount importance in metal reactions due to the much higher temperatures reached during combustion. Second, a low-gravity environment is absolutely essential to remove the destructive effect of gravity on the shape of a molten metal droplet in order to study a spherically symmetric condition with large bulk samples. The larger size of the spherical metal droplet and the longer burning times available in reduced gravity extend the spatial and temporal dimensions to permit careful probing of the flame structure and dynamics. Third, the influence of the radiative heat transfer from the solid oxides can be studied more carefully by generating a stagnant spherical shell of condensed products undisturbed by buoyancy.

Influence of thermally activated processes on the deformation behavior during low temperature ECAP

NASA Astrophysics Data System (ADS)

Fritsch, S.; Scholze, M.; F-X Wagner, M.

2016-03-01

High strength aluminum alloys are generally hard to deform. Therefore, the application of conventional severe plastic deformation methods to generate ultrafine-grained microstructures and to further increase strength is considerably limited. In this study, we consider low temperature deformation in a custom-built, cooled equal channel angular pressing (ECAP) tool (internal angle 90°) as an alternative approach to severely plastically deform a 7075 aluminum alloy. To document the maximum improvement of mechanical properties, these alloys are initially deformed from a solid solution heat-treated condition. We characterize the mechanical behavior and the microstructure of the coarse grained initial material at different low temperatures, and we analyze how a tendency for the PLC effect and the strain-hardening rate affect the formability during subsequent severe plastic deformation at low temperatures. We then discuss how the deformation temperature and velocity influence the occurrence of PLC effects and the homogeneity of the deformed ECAP billets. Besides the mechanical properties and these microstructural changes, we discuss technologically relevant processing parameters (such as pressing forces) and practical limitations, as well as changes in fracture behavior of the low temperature deformed materials as a function of deformation temperature.

Near room temperature chemical vapor deposition of graphene with diluted methane and molten gallium catalyst.

PubMed

Fujita, Jun-Ichi; Hiyama, Takaki; Hirukawa, Ayaka; Kondo, Takahiro; Nakamura, Junji; Ito, Shin-Ichi; Araki, Ryosuke; Ito, Yoshikazu; Takeguchi, Masaki; Pai, Woei Wu

2017-09-28

Direct growth of graphene integrated into electronic devices is highly desirable but difficult due to the nominal ~1000 °C chemical vapor deposition (CVD) temperature, which can seriously deteriorate the substrates. Here we report a great reduction of graphene CVD temperature, down to 50 °C on sapphire and 100 °C on polycarbonate, by using dilute methane as the source and molten gallium (Ga) as catalysts. The very low temperature graphene synthesis is made possible by carbon attachment to the island edges of pre-existing graphene nuclei islands, and causes no damages to the substrates. A key benefit of using molten Ga catalyst is the enhanced methane absorption in Ga at lower temperatures; this leads to a surprisingly low apparent reaction barrier of ~0.16 eV below 300 °C. The faster growth kinetics due to a low reaction barrier and a demonstrated low-temperature graphene nuclei transfer protocol can facilitate practical direct graphene synthesis on many kinds of substrates down to 50-100 °C. Our results represent a significant progress in reducing graphene synthesis temperature and understanding its mechanism.

Optimum design on refrigeration system of high-repetition-frequency laser

NASA Astrophysics Data System (ADS)

Li, Gang; Li, Li; Jin, Yezhou; Sun, Xinhua; Mao, Shaojuan; Wang, Yuanbo

2014-12-01

A refrigeration system with fluid cycle, semiconductor cooler and air cooler is designed to solve the problems of thermal lensing effect and unstable output of high-repetition-frequency solid-state lasers. Utilizing a circulating water pump, water recycling system carries the water into laser cavity to absorb the heat then get to water cooling head. The water cooling head compacts cold spot of semiconductor cooling chips, so the heat is carried to hot spot which contacts the radiating fins, then is expelled through cooling fan. Finally, the cooled water return to tank. The above processes circulate to achieve the purposes of highly effective refrigeration in miniative solid-state lasers.The refrigeration and temperature control components are designed strictly to ensure refrigeration effect and practicability. we also set up a experiment to test the performances of this refrigeration system, the results show that the relationship between water temperature and cooling power of semiconductor cooling chip is linear at 20°C-30°C (operating temperature range of Nd:YAG), the higher of the water temperature, the higher of cooling power. According to the results, cooling power of single semiconductor cooling chip is above 60W, and the total cooling power of three semiconductor cooling chips achieves 200W that will satisfy the refrigeration require of the miniative solid-state lasers.The performance parameters of laser pulse are also tested, include pulse waveform, spectrogram and laser spot. All of that indicate that this refrigeration system can ensure the output of high-repetition-frequency pulse whit high power and stability.

Material System Engineering for Advanced Electrocaloric Cooling Technology

NASA Astrophysics Data System (ADS)

Qian, Xiaoshi

Electrocaloric effect refers to the entropy change and/or temperature change in dielectrics caused by the electric field induced polarization change. Recent discovery of giant ECE provides an opportunity to realize highly efficient cooling devices for a broad range of applications ranging from household appliances to industrial applications, from large-scale building thermal management to micro-scale cooling devices. The advances of electrocaloric (EC) based cooling device prototypes suggest that highly efficient cooling devices with compact size are achievable, which could lead to revolution in next generation refrigeration technology. This dissertation focuses on both EC based materials and cooling devices with their recent advances that address practical issues. Based on better understandings in designing an EC device, several EC material systems are studied and improved to promote the performances of EC based cooling devices. In principle, applying an electric field to a dielectric would cause change of dipolar ordering states and thus a change of dipolar entropy. Giant ECE observed in ferroelectrics near ferroelectric-paraelectric (FE-PE) transition temperature is owing to the large dipolar orientation change, between random-oriented dipolar states in paraelectric phase and spontaneous-ordered dipolar states in ferroelectric phases, which is induced by external electric fields. Besides pursuing large ECE, studies on EC cooling devices indicated that EC materials are required to possess wide operational temperature window, in which large ECE can be maintained for efficient operations. Although giant ECE was first predicted in ferroelectric polymers, where the large effect exhibits near FEPE phase transition, the narrow operation temperature window poses obstacles for these normal ferroelectrics to be conveniently perform in wide range of applications. In this dissertation, we demonstrated that the normal ferroelectric polymers can be converted to relaxor ferroelectric polymers which possess both giant ECE (27 Kelvin temperature drop) and much wider operating temperature window (over 50 kelvin covering RT) by proper defect modification which delicately tailors ferroelectrics in meso-, micro- and molecular scales. In addition, in order to be practical, EC device requires EC material can be driven at low electric fields upon achieve the large ECE. It is demonstrated in this dissertation that by facially modifying materials structure in meso-, micro- and molecular scale, lowfield ECE can be greatly improved. Large ECE, induced by low electric fields and existing in wide temperature window, is a major improvement in EC materials for practical applications. Besides EC polymers, this thesis also investigated EC ceramics. Due to several unique opportunities offered by the EC ceramics, Ba(ZrxTi 1-x)O3 (BZT), that is studied. (i) This class of EC ceramics offers a possibility to explore the invariant critical point (ICP), which maximizes the number of coexistent phase and provides a nearly vanishing energy barrier for switching among different phases. As demonstrated in this thesis, the BZT bulk ceramics at x˜ 0.2 exhibits a large adiabatic temperature drop DeltaTc=4.5 K, a large isothermal entropy change DeltaS = 8 Jkg-1K-1, a large EC coefficient (|DeltaT c/DeltaE| = 0.52x10-6 KmV-1 and DeltaS/DeltaE=0.93x10 -6 Jmkg-1K-1V-1) over a wide operating temperature range Tspan>30K. (ii) The thermal conductivity of EC ceramics is in general, much higher than that of EC polymers, and consequently they will allow EC cooling configurations which are not accessible by the EC polymers. Moreover, in the same device configuration, the high thermal conductivity of EC ceramics (kappa> 5 W/mK, compared with EC polymer, ˜ 0.25 W/mK) allows higher operation frequency and therefore a higher cooling power. (iii) Well-established fabrication processes of multilayer ceramic capacitor (MLCC) provide a foundation for the EC ceramic toward mass production. In this thesis, BZT thick film double layers have been fabricated and large ECE has been directly measured. EC induced temperature drop (DeltaT) around 6.3 °C and entropy change (DeltaS) of 11.0 Jkg-1K -1 are observed under an electric field of DeltaE=14.6 MV/m at 40 °C was observed in BZT thick film double layers. The result encourages further investigations on ECE in MLCC for practical applications. (Abstract shortened by ProQuest.).

Analysis and Design of Cryogenic Pressure Vessels for Automotive Hydrogen Storage

NASA Astrophysics Data System (ADS)

Espinosa-Loza, Francisco Javier

Cryogenic pressure vessels maximize hydrogen storage density by combining the high pressure (350-700 bar) typical of today's composite pressure vessels with the cryogenic temperature (as low as 25 K) typical of low pressure liquid hydrogen vessels. Cryogenic pressure vessels comprise a high-pressure inner vessel made of carbon fiber-coated metal (similar to those used for storage of compressed gas), a vacuum space filled with numerous sheets of highly reflective metalized plastic (for high performance thermal insulation), and a metallic outer jacket. High density of hydrogen storage is key to practical hydrogen-fueled transportation by enabling (1) long-range (500+ km) transportation with high capacity vessels that fit within available spaces in the vehicle, and (2) reduced cost per kilogram of hydrogen stored through reduced need for expensive structural material (carbon fiber composite) necessary to make the vessel. Low temperature of storage also leads to reduced expansion energy (by an order of magnitude or more vs. ambient temperature compressed gas storage), potentially providing important safety advantages. All this is accomplished while simultaneously avoiding fuel venting typical of cryogenic vessels for all practical use scenarios. This dissertation describes the work necessary for developing and demonstrating successive generations of cryogenic pressure vessels demonstrated at Lawrence Livermore National Laboratory. The work included (1) conceptual design, (2) detailed system design (3) structural analysis of cryogenic pressure vessels, (4) thermal analysis of heat transfer through cryogenic supports and vacuum multilayer insulation, and (5) experimental demonstration. Aside from succeeding in demonstrating a hydrogen storage approach that has established all the world records for hydrogen storage on vehicles (longest driving range, maximum hydrogen storage density, and maximum containment of cryogenic hydrogen without venting), the work also demonstrated a methodology for computationally efficient detailed modeling of cryogenic pressure vessels. The work continues with support of the US Department of Energy to demonstrate a new generation of cryogenic vessels anticipated to improve on the hydrogen storage performance figures previously imposed in this project. The author looks forward to further contributing to a future of long-range, inexpensive, and safe zero emissions transportation.

High temperature superconductor NB3Ga

NASA Technical Reports Server (NTRS)

Vieland, L. J.; Wicklund, A. W.

1973-01-01

The discovery of superconductivity at 20.3 K in the Nb-Ga system by applying chemical vapor deposition (CVD) techniques to the materials preparation problem is reported. Films on ceramic substrates have been grown with superconducting onsets of up to 20.3 K. Critical fields at 4.2 K in excess of 300 kG and alpha's of 1100,000 T-A/sq cm have been obtained. The results confirm that the outstanding properties of Nb-Ga are due to an equilibrium configuration of the system, namely, the stoichiometric A-15 compound Nb3Ga, which is stable at relatively low temperatures. Practical materials preparation problems center on the codeposition of an adjacent Nb5Ga3 phase and the requirement that the deposition temperature be low. Some ternary alloys were also prepared, with part of the Ga replaced by Sn, Sb, Al, or Ge.

Moderate temperature sodium cells. V - Discharge reactions and rechargeability of NiS and NiS2 positive electrodes in molten NaAlCl4

NASA Technical Reports Server (NTRS)

Abraham, K. M.; Elliot, J. E.

1984-01-01

NiS2 and NiS have been characterized as high energy density rechargeable positive electrodes for moderate-temperature Na batteries of the configuration, Na(1)/beta double prime-Al2O3/NaAlCl4(1), NiSx. The batteries operate in the temperature range 170 - 190 C. Positive electrode reactions during discharge/charge cycles have been characterized. Excellent rechargeability of the batteries has been demonstrated by extended cell cycling. A Na/NiS2 cell, operating at 190 C, exceeded 600 deep discharge/charge cycles with practically no capacity deterioration. The feasibility of secondary Na/NiSx batteries with specific energies equal to or greater than 50 Wh/lb and cycle lifes exceeding 1000 deep discharge/charge cycles has been demonstrated.

Lorentz violation, gravitoelectromagnetism and Bhabha scattering at finite temperature

NASA Astrophysics Data System (ADS)

Santos, A. F.; Khanna, Faqir C.

2018-04-01

Gravitoelectromagnetism (GEM) is an approach for the gravitation field that is described using the formulation and terminology similar to that of electromagnetism. The Lorentz violation is considered in the formulation of GEM that is covariant in its form. In practice, such a small violation of the Lorentz symmetry may be expected in a unified theory at very high energy. In this paper, a non-minimal coupling term, which exhibits Lorentz violation, is added as a new term in the covariant form. The differential cross-section for Bhabha scattering in the GEM framework at finite temperature is calculated that includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to calculate the total differential cross-section at finite temperature. The contribution due to Lorentz violation is isolated from the total cross-section. It is found to be small in magnitude.

Magneto-optical imaging of polycrystalline FeTe 1-xSe x prepared at various conditions

NASA Astrophysics Data System (ADS)

Ding, Q.; Taen, T.; Mohan, S.; Nakajima, Y.; Tamegai, T.

2011-11-01

We have prepared high-quality polycrystalline FeTe1-xSex by sintering at different temperatures and characterized their structural and magnetic properties with X-ray diffraction, magnetization measurements, and magneto-optical imaging. The intragranular Jc was estimated to be 5 × 104A/cm2, which is smaller than the single crystal, but still in the range for practical applications.

Close-Spaced High Temperature Knudsen Flow.

DTIC Science & Technology

1986-07-15

work~was a study of discharge processes in Knudsen mode (collisionless), thermionic energy converters. Areas of research involve’mechanisms for reducing ...power densities. The mechanisms/we have chosen to study are: reduction of space-charge through a very close interelectrode gap (less than 10 microns...In order to operate at practical current densities, the effect of electron space charge must be reduced . This can be done through very close

Compatibility between Co-Metallized PbTe Thermoelectric Legs and an Ag–Cu–In Brazing Alloy

PubMed Central

Ben-Ayoun, Dana; Sadia, Yatir; Gelbstein, Yaniv

2018-01-01

In thermoelectric (TE) generators, maximizing the efficiency of conversion of direct heat to electricity requires the reduction of any thermal and electrical contact resistances between the TE legs and the metallic contacts. This requirement is especially challenging in the development of intermediate to high-temperature TE generators. PbTe-based TE materials are known to be highly efficient up to temperatures of around 500 °C; however, only a few practical TE generators based on these materials are currently commercially available. One reason for that is the insufficient bonding techniques between the TE legs and the hot-side metallic contacts. The current research is focused on the interaction between cobalt-metallized n-type 9.104 × 10−3 mol % PbI2-doped PbTe TE legs and the Ag0.32Cu0.43In0.25 brazing alloy, which is free of volatile species. Clear and fine interfaces without any noticeable formation of adverse brittle intermetallic compounds were observed following prolonged thermal treatment testing. Moreover, a reasonable electrical contact resistance of ~2.25 mΩmm2 was observed upon brazing at 600 °C, highlighting the potential of such contacts while developing practical PbTe-based TE generators. PMID:29320430

Experiment study of bio-tissue's temperature irradiated by laser based on optical fiber F-P sensor

NASA Astrophysics Data System (ADS)

Shan, Ning; Liu, Xia

2014-08-01

Laser has several advantages, such as strong anti-interference ability, quick speed, high power, agility and precision. It is widely applied in military and medicine fields. When laser acts on human body, biological tissue of human body will appear the phenomenon of ablation and carbonization and solidification. In order to effectively defend excess damage by laser, the thermal effect research of skin tissue should be carried out. Temperature is a key parameter in the processing between laser and bio-tissue. It is the mostly foundation using analyze size of thermal damage area and forecast thermal damage degree. In this paper, the low fineness optical fiber F-P sensing system for temperature measurement is designed and established. The real-time measurement system of temperature generated by laser irradiating bio-tissue is build based on the sensing system. The temperature distributing generated by laser in the bio-tissue is studied through experiment when the spot diameter of emission laser is difference with the same energy density and the energy density is difference with the same spot diameter of emission laser. The experimental results show that the sensing system can be used to the real-time temperature measurement of bio-tissue efficiency. It has small bulk. Its outer diameter is 250μm. And the hurt for bio-tissue is small. It has high respond speed. The respond time of temperature is less than 1s. These can be satisfied with practice demand. When the energy density of laser is same, the temperature rising in the same location is low along the spot diameter of emission laser increasing. When the spot diameter of emission laser is same, the temperature rising in the same location is increasing along with the energy density of laser increasing.

High-performance graphene/sulphur electrodes for flexible Li-ion batteries using the low-temperature spraying method.

PubMed

Kumar, Pushpendra; Wu, Feng-Yu; Hu, Lung-Hao; Ali Abbas, Syed; Ming, Jun; Lin, Chia-Nan; Fang, Jason; Chu, Chih-Wei; Li, Lain-Jong

2015-05-07

Elementary sulphur (S) has been shown to be an excellent cathode material in energy storage devices such as Li-S batteries owing to its very high capacity. The major challenges associated with the sulphur cathodes are structural degradation, poor cycling performance and instability of the solid-electrolyte interphase caused by the dissolution of polysulfides during cycling. Tremendous efforts made by others have demonstrated that encapsulation of S materials improves their cycling performance. To make this approach practical for large scale applications, the use of low-cost technology and materials has become a crucial and new focus of S-based Li-ion batteries. Herein, we propose to use a low temperature spraying process to fabricate graphene/S electrode material, where the ink is composed of graphene flakes and the micron-sized S particles prepared by grinding of low-cost S powders. The S particles are found to be well hosted by highly conductive graphene flakes and consequently superior cyclability (∼70% capacity retention after 250 cycles), good coulombic efficiency (∼98%) and high capacity (∼1500 mA h g(-1)) are obtained. The proposed approach does not require high temperature annealing or baking; hence, another great advantage is to make flexible Li-ion batteries. We have also demonstrated two types of flexible batteries using sprayed graphene/S electrodes.

Operation characteristic of a heat pump of mechanical vapor recompression propelled by fans and its performance analysis applied to waste-water treatment

NASA Astrophysics Data System (ADS)

Weike, Pang; Wenju, Lin; Qilin, Pan; Wenye, Lin; Qunte, Dai; Luwei, Yang; Zhentao, Zhang

2014-01-01

In this paper, a set of heat pump (called as Mechanical Vapor Recompression, MVR) propelled by a centrifugal fan is tested and it shows some special characteristic when it works together with a falling film evaporator. Firstly, an analysis of the fan's suction and discharge parameters at stable state, such as its pressure and temperature, indicates that a phenomenon of wet compression is probably to appear during vapor compression. As a result, superheat after saturated vapor is compressed is eliminated, which reduces discharge temperature of the system. It is because drops boil away and absorb the super heat into their latent heat during vapor compression. Meanwhile, drops in the suction vapor add to the compressed vapor, which increase the given heat of the MVR heat pump. Next, assistant electric heat could adjust and keep steady of the operating pressure and temperature of an MVR heat pump. With the evaporation temperature up to be high, heat balance is broken and supplement heat needs to increase. Thirdly, the performance of an MVR heat pump is affect by the balance of falling film and evaporation that has an effect on heat transfer. Then, two parameters standing for the performance are measured as it runs in practical condition. The two important parameters are consumptive electricity power and productive water capacity. According to theoretical work in ideal condition by calculation and fan's input power by measure as running, adiabatic efficiency (ηad) of a centrifugal fan is calculated when it is applied in a heat pump of MVR. Following, based on ηad, practical SMER and COP of an MVR heat pump are discovered to be correlative with it. Finally, in dependence on productive water in theory and in practice, displacement efficiency (ηv) of centrifugal fans is obtained when compressing vapor, and so provide some references of matching a fan for an MVR heat pump. On the other hand, it is helpful to research and develop MVR heat pumps, and also to check electricity power consumption while operating practically in light of electric motor efficiency (ηe) and ηad.

Practical deviations from Henry`s law for water/air partitioning of volatile organic compounds

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

Schabron, J.F.; Rovani, J.F. Jr.

A study was conducted to define parameters relating to the use of a down hole submersible photoionization detector (PID) probe to measure volatile organic compounds (VOCs) in an artificial headspace. The partitioning of toluene and trichloroethylene between water and air was studied as a function of analyte concentration and water temperature. The Henry`s law constant governing this partitioning represents an ideal condition at infinite dilution for a particular temperature. The results show that in practice. this partitioning is far from ideal. Conditions resulting in apparent, practical deviations from Henry`s law include temperature and VOC concentration. Thus, a single value ofmore » Henry`s law constant for a particular VOC such as toluene can provide only an approximation of concentration in the field. Detector response in saturated humidity environments as a function of water temperature and analyte concentration was studied also.« less

Pollutant emissions from and within a model gas turbine combustor at elevated pressures and temperatures

NASA Technical Reports Server (NTRS)

Drennan, S. A.; Peterson, C. O.; Khatib, F. M.; Sowa, W. A.; Samuelsen, G. S.

1993-01-01

Conventional and advanced gas turbine engines are coming under increased scrutiny regarding pollutant emissions. This, in turn, has created a need to obtain in-situ experimental data at practical conditions, as well as exhaust data, and to obtain the data in combustors that reflect modern designs. The in-situ data are needed to (1) assess the effects of design modifications on pollutant formation, and (2) develop a detailed data base on combustor performance for the development and verification of computer modeling. This paper reports on a novel high pressure, high temperature facility designed to acquire such data under controlled conditions and with access (optical and extractive) for in-situ measurements. To evaluate the utility of the facility, a model gas turbine combustor was selected which features practical hardware design, two rows of jets (primary and dilution) with four jets in each row, and advanced wall cooling techniques with laser drilled effusive holes. The dome is equipped with a flat-vaned swirler with vane angles of 60 degrees. Data are obtained at combustor pressures ranging from 2 to 10 atmospheres of pressure, levels of air preheat to 427 C, combustor reference velocities from 10.0 to 20.0 m/s, and an overall equivalence ratio of 0.3. Exit plane and in-situ measurements are presented for HC, O2, CO2, CO, and NO(x). The exit plane emissions of NO(x) correspond to levels reported from practical combustors and the in-situ data demonstrate the utility and potential for detailed flow field measurements.

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

Tan, Lizhen; Yang, Ying; Tyburska-Puschel, Beata

The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computational tools)more » is an important path to more efficient alloy development and process optimization. Ferritic-martensitic (FM) steels are important structural materials for nuclear reactors due to their advantages over other applicable materials like austenitic stainless steels, notably their resistance to void swelling, low thermal expansion coefficients, and higher thermal conductivity. However, traditional FM steels exhibit a noticeable yield strength reduction at elevated temperatures above ~500°C, which limits their applications in advanced nuclear reactors which target operating temperatures at 650°C or higher. Although oxide-dispersion-strengthened (ODS) ferritic steels have shown excellent high-temperature performance, their extremely high cost, limited size and fabricability of products, as well as the great difficulty with welding and joining, have limited or precluded their commercial applications. Zirconium has shown many benefits to Fe-base alloys such as grain refinement, improved phase stability, and reduced radiation-induced segregation. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of a new generation of Zr-bearing ferritic alloys to be fabricated using conventional steelmaking practices, which have excellent radiation resistance and enhanced high-temperature creep performance greater than Grade 91.« less

Supercritical Brayton Cycle Nuclear Power System Concepts

NASA Astrophysics Data System (ADS)

Wright, Steven A.

2007-01-01

Both the NASA and DOE have programs that are investigating advanced power conversion cycles for planetary surface power on the moon or Mars, and for next generation nuclear power plants on earth. The gas Brayton cycle offers many practical solutions for space nuclear power systems and was selected as the nuclear power system of choice for the NASA Prometheus project. An alternative Brayton cycle that offers high efficiency at a lower reactor coolant outlet temperature is the supercritical Brayton cycle (SCBC). The supercritical cycle is a true Brayton cycle because it uses a single phase fluid with a compressor inlet temperature that is just above the critical point of the fluid. This paper describes the use of a supercritical Brayton cycle that achieves a cycle efficiency of 26.6% with a peak coolant temperature of 750 K and for a compressor inlet temperature of 390 K. The working fluid uses a clear odorless, nontoxic refrigerant C318 perflurocarbon (C4F8) that always operates in the gas phase. This coolant was selected because it has a critical temperature and pressure of 388.38 K and 2.777 MPa. The relatively high critical temperature allows for efficient thermal radiation that keeps the radiator mass small. The SCBC achieves high efficiency because the loop design takes advantage of the non-ideal nature of the coolant equation of state just above the critical point. The lower coolant temperature means that metal fuels, uranium oxide fuels, and uranium zirconium hydride fuels with stainless steel, ferretic steel, or superalloy cladding can be used with little mass penalty or reduction in cycle efficiency. The reactor can use liquid-metal coolants and no high temperature heat exchangers need to be developed. Indirect gas cooling or perhaps even direct gas cooling can be used if the C4F8 coolant is found to be sufficiently radiation tolerant. Other fluids can also be used in the supercritical Brayton cycle including Propane (C3H8, Tcritical = 369 K) and Hexane (C6H14, Tcritical = 506.1 K) provided they have adequate chemical compatibility and stability. Overall the use of supercritical Brayton cycles may offer ``break through'' operating capabilities for space nuclear power plants because high efficiencies can be achieved a very low reactor operating temperatures which in turn allows for the use of available fuels, cladding, and structural materials.

Lunar oxygen and metal for use in near-Earth space: Magma electrolysis

NASA Technical Reports Server (NTRS)

Colson, Russell O.; Haskin, Larry A.

1990-01-01

Because it is energetically easier to get material from the Moon to Earth orbit than from the Earth itself, the Moon is a potentially valuable source of materials for use in space. The unique conditions on the Moon, such as vacuum, absence of many reagents common on the Earth, and the presence of very nontraditional ores suggest that a unique and nontraditional process for extracting materials from the ores may prove the most practical. With this in mind, an investigation of unfluxed silicate electrolysis as a method for extracting oxygen, iron, and silicon from lunar regolith was initiated and is discussed. The advantages of the process include simplicity of concept, absence of need to supply reagents from Earth, and low power and mass requirements for the processing plant. Disadvantages include the need for uninterrupted high temperature and the highly corrosive nature of the high-temperature silicate melts which has made identifying suitable electrode and container materials difficult.

A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte

PubMed Central

Jeong, Goojin; Kim, Hansu; Sug Lee, Hyo; Han, Young-Kyu; Hwan Park, Jong; Hwan Jeon, Jae; Song, Juhye; Lee, Keonjoon; Yim, Taeeun; Jae Kim, Ki; Lee, Hyukjae; Kim, Young-Jun; Sohn, Hun-Joon

2015-01-01

Sodium rechargeable batteries can be excellent alternatives to replace lithium rechargeable ones because of the high abundance and low cost of sodium; however, there is a need to further improve the battery performance, cost-effectiveness, and safety for practical use. Here we demonstrate a new type of room-temperature and high-energy density sodium rechargeable battery using an SO2-based inorganic molten complex catholyte, which showed a discharge capacity of 153 mAh g−1 based on the mass of catholyte and carbon electrode with an operating voltage of 3 V, good rate capability and excellent cycle performance over 300 cycles. In particular, non-flammability and intrinsic self-regeneration mechanism of the inorganic liquid electrolyte presented here can accelerate the realization of commercialized Na rechargeable battery system with outstanding reliability. Given that high performance and unique properties of Na–SO2 rechargeable battery, it can be another promising candidate for next generation energy storage system. PMID:26243052

230% room-temperature magnetoresistance in CoFeB /MgO/CoFeB magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Djayaprawira, David D.; Tsunekawa, Koji; Nagai, Motonobu; Maehara, Hiroki; Yamagata, Shinji; Watanabe, Naoki; Yuasa, Shinji; Suzuki, Yoshishige; Ando, Koji

2005-02-01

Magnetoresistance (MR) ratio up to 230% at room temperature (294% at 20 K) has been observed in spin-valve-type magnetic tunnel junctions (MTJs) using MgO tunnel barrier layer fabricated on thermally oxidized Si substrates. We found that such a high MR ratio can be obtained when the MgO barrier layer was sandwiched with amorphous CoFeB ferromagnetic electrodes. Microstructure analysis revealed that the MgO layer with (001) fiber texture was realized when the MgO layer was grown on amorphous CoFeB rather than on polycrystalline CoFe. Since there have been no theoretical studies on the MTJs with a crystalline tunnel barrier and amorphous electrodes, the detailed mechanism of the huge tunneling MR effect observed in this study is not clear at the present stage. Nevertheless, the present work is of paramount importance in realizing high-density magnetoresistive random access memory and read head for ultra high-density hard-disk drives into practical use.

Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Tigelaar, Dean M.; Chapin, Kara; Bennett, William R.

2007-01-01

Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

An air-stable Na 3SbS 4 superionic conductor prepared by a rapid and economic synthetic procedure

DOE PAGES

Wang, Hui; Chen, Yan; Hood, Zachary D.; ...

2016-01-01

All-solid-state sodium batteries, using abundant sodium resources and solid electrolyte, hold much promise for safe, low cost, large-scale energy storage. To realize the practical applications of all solid Na-ion batteries at ambient temperature, the solid electrolytes are required to have high ionic conductivity, chemical stability, and ideally, easy preparation. Ceramic electrolytes show higher ionic conductivity than polymers, but they often require extremely stringent synthesis conditions, either high sintering temperature above 1000 C or long-time, low-energy ball milling. Herein, we report a new synthesis route for Na 3SbS 4, a novel Na superionic conductor that needs much lower processing temperature belowmore » 200 C and easy operation. This new solid electrolyte exhibits a remarkable ionic conductivity of 1.05 mS cm -1 at 25 °C and is chemically stable under ambient atmosphere. In conclusion, this synthesis process provides unique insight into the current state-of-the-art solid electrolyte preparation and opens new possibilities for the design of similar materials.« less

Production of long chain omega-3 fatty acids and carotenoids in tropical areas by a new heat-tolerant microalga Tetraselmis sp. DS3.

PubMed

Tsai, Hsin-Pei; Chuang, Lu-Te; Chen, Ching-Nen Nathan

2016-02-01

Demand for long chain ω-3 fatty acids from non-fish source for vegetarians has increased recently. Marine microalgae are the primary producers of EPA/DHA and promising alternatives for fish oil. Tropical areas have abundant sunlight throughout the year for microalgal cultivation but this practice can be hindered by high temperature. Discovery of heat-tolerant marine microalgae that can synthesize EPA/DHA will solve these problems. A new species of microalga was isolated from a high temperature lagoon and identified as Tetraselmis sp. DS3. These cells could grow at 40 °C, the highest temperature for marine microalgal growth ever reported. Its ω-3 fatty acids and EPA accounted for 33 and 10% of total lipids, respectively, grown in nitrogen-depleted conditions. These cells also accumulated more than 5% β-carotene and 0.48% lutein in biomass. This new microalga can be cultivated for long chain ω-3 fatty acids and lutein production in the tropical areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Sacrificial Coating Strategy Toward Enhancement of Metal-Support Interaction for Ultrastable Au Nanocatalysts

DOE PAGES

Zhan, Wangcheng; He, Qian; Liu, Xiaofei; ...

2016-11-22

Supported gold (Au) nanocatalysts hold great promise for heterogeneous catalysis; however, their practical application is greatly hampered by poor thermodynamic stability. Herein, a general synthetic strategy is reported where discrete metal nanoparticles are made resistant to sintering, preserving their catalytic activities in high-temperature oxidation processes. Taking advantage of the unique coating chemistry of dopamine, sacrificial carbon layers are constructed on the material surface, stabilizing the supported catalyst. Upon annealing at high temperature under an inert atmosphere, the interactions between support and metal nanoparticle are dramatically enhanced, while the sacrificial carbon layers can be subsequently removed through oxidative calcination in air.more » Owing to the improved metal-support contact and strengthened electronic interactions, the resulting Au nanocatalysts are resistant to sintering and exhibit excellent durability for catalytic combustion of propylene at elevated temperatures. Moreover, the facile synthetic strategy can be extended to the stabilization of other supported catalysts on a broad range of supports, providing a general approach to enhancing the thermal stability and sintering resistance of supported nanocatalysts.« less

Reversible calcium alloying enables a practical room-temperature rechargeable calcium-ion battery with a high discharge voltage

NASA Astrophysics Data System (ADS)

Wang, Meng; Jiang, Chunlei; Zhang, Songquan; Song, Xiaohe; Tang, Yongbing; Cheng, Hui-Ming

2018-06-01

Calcium-ion batteries (CIBs) are attractive candidates for energy storage because Ca2+ has low polarization and a reduction potential (-2.87 V versus standard hydrogen electrode, SHE) close to that of Li+ (-3.04 V versus SHE), promising a wide voltage window for a full battery. However, their development is limited by difficulties such as the lack of proper cathode/anode materials for reversible Ca2+ intercalation/de-intercalation, low working voltages (<2 V), low cycling stability, and especially poor room-temperature performance. Here, we report a CIB that can work stably at room temperature in a new cell configuration using graphite as the cathode and tin foils as the anode as well as the current collector. This CIB operates on a highly reversible electrochemical reaction that combines hexafluorophosphate intercalation/de-intercalation at the cathode and a Ca-involved alloying/de-alloying reaction at the anode. An optimized CIB exhibits a working voltage of up to 4.45 V with capacity retention of 95% after 350 cycles.

The effect of high pressure at subzero temperature on proteins solubility, drip loss and texture of fish (cod and salmon) and mammal's (pork and beef) meat.

PubMed

Malinowska-Pańczyk, Edyta; Walecka, Marta; Pawłowicz, Roman; Tylingo, Robert; Kołodziejska, Ilona

2014-07-01

One of the possibilities of using high-pressure technique in inactivation of microorganism is conducting this process at subzero temperature. However, for its practical application in meat preservation the appropriate properties of meat should be maintained. Therefore, the aim of this work was to examine the effect of pressure at subzero temperature (without freezing of water) on proteins and texture of mammal's and cold-adapted fish meat. The data showed that cod and salmon meat proteins were more susceptible to pressure-induced denaturation/aggregation than beef and pork proteins. Glucose and saccharose exerted protective effect on fish meat proteins treated with pressure of 111 MPa(tc) and -10 degrees C but not at 193 MPa(tc) and -20 degrees C. The pressure treatment under the latter conditions increased cook loss of fish meat but not of mammal's meat. However, after cooking the hardness of all kinds of pressurized meat was at the same level as that for unpressurized cooked samples.

Rapidly-Deposited Polydopamine Coating via High Temperature and Vigorous Stirring: Formation, Characterization and Biofunctional Evaluation

PubMed Central

Zhou, Ping; Deng, Yi; Lyu, Beier; Zhang, Ranran; Zhang, Hai; Ma, Hongwei; Lyu, Yalin; Wei, Shicheng

2014-01-01

Polydopamine (PDA) coating provides a promising approach for immobilization of biomolecules onto almost all kinds of solid substrates. However, the deposition kinetics of PDA coating as a function of temperature and reaction method is not well elucidated. Since dopamine self-polymerization usually takes a long time, therefore, rapid-formation of PDA film becomes imperative for surface modification of biomaterials and medical devices. In the present study, a practical method for preparation of rapidly-deposited PDA coating was developed using a uniquely designed device, and the kinetics of dopamine self-polymerization was investigated by QCM sensor system. It was found that high temperature and vigorous stirring could dramatically speed up the formation of PDA film on QCM chip surface. Surface characterization, BSA binding study, cell viability assay and antibacterial test demonstrates that the polydopamine coating after polymerization for 30 min by our approach exhibits similar properties to those of 24 h counterpart. The method has a great potential for rapid-deposition of polydopamine films to modify biomaterial surfaces. PMID:25415328

Joining of Silicon Carbide-Based Ceramics by Reaction Forming Method

NASA Technical Reports Server (NTRS)

Singh, M.; Kiser, J. D.

1997-01-01

Recently, there has been a surge of interest in the development and testing of silicon-based ceramics and composite components for a number of aerospace and ground based systems. The designs often require fabrication of complex shaped parts which can be quite expensive. One attractive way of achieving this goal is to build up complex shapes by joining together geometrically simple shapes. However, the joints should have good mechanical strength and environmental stability comparable to the bulk materials. These joints should also be able to maintain their structural integrity at high temperatures. In addition, the joining technique should be practical, reliable, and affordable. Thus, joining has been recognized as one of the enabling technologies for the successful utilization of silicon carbide based ceramic components in high temperature applications. Overviews of various joining techniques, i.e., mechanical fastening, adhesive bonding, welding, brazing, and soldering have been provided in recent publications. The majority of the techniques used today are based on the joining of monolithic ceramics with metals either by diffusion bonding, metal brazing, brazing with oxides and oxynitrides, or diffusion welding. These techniques need either very high temperatures for processing or hot pressing (high pressures). The joints produced by these techniques have different thermal expansion coefficients than the ceramic materials, which creates a stress concentration in the joint area. The use temperatures for these joints are around 700 C. Ceramic joint interlayers have been developed as a means of obtaining high temperature joints. These joint interlayers have been produced via pre-ceramic polymers, in-situ displacement reactions, and reaction bonding techniques. Joints produced by the pre-ceramic polymer approach exhibit a large amounts of porosity and poor mechanical properties. On the other hand, hot pressing or high pressures are needed for in-situ displacement reactions and reaction bonding techniques. Due to the equipment required, these techniques are impractical for joining large or complex shaped components.

Peroxy-Titanium Complex-based inks for low temperature compliant anatase thin films.

PubMed

Shabanov, N S; Asvarov, A Sh; Chiolerio, A; Rabadanov, K Sh; Isaev, A B; Orudzhev, F F; Makhmudov, S Sh

2017-07-15

Stable highly crystalline titanium dioxide colloids are of paramount importance for the establishment of a solution-processable library of materials that could help in bringing the advantages of digital printing to the world of photocatalysis and solar energy conversion. Nano-sized titanium dioxide in the anatase phase was synthesized by means of hydrothermal methods and treated with hydrogen peroxide to form Peroxy-Titanium Complexes (PTCs). The influence of hydrogen peroxide on the structural, optical and rheological properties of titanium dioxide and its colloidal solutions were assessed and a practical demonstration of a low temperature compliant digitally printed anatase thin film given. Copyright © 2017 Elsevier Inc. All rights reserved.

Development of a Thermal Rectifier Usable at High Temperature

NASA Astrophysics Data System (ADS)

Takeuchi, Tsunehiro; Goto, Hiroki; Toyama, Yasuhiro; Itoh, Takashi; Mikami, Masashi

2011-05-01

By using Al-based metallic alloys characterized by a disordered structure and a narrow pseudogap of a few hundred meV in energy width persisting at the Fermi level, we succeeded in preparing materials possessing a large increase of thermal conductivity with increasing temperature. This unusual increase of thermal conductivity is caused by the electronic structure effect known as the bipolar diffusion effect (BDE) in the context of the two-band model. A thermal rectifier was constructed using materials exhibiting the BDE. By showing the thermal rectification of the bulk sample prepared in this study, we demonstrate that our newly proposed idea of a thermal rectifier using the BDE is applicable for practical use.

Evaluation of the Optimum Composition of Low-Temperature Fuel Cell Electrocatalysts for Methanol Oxidation by Combinatorial Screening.

PubMed

Antolini, Ermete

2017-02-13

Combinatorial chemistry and high-throughput screening represent an innovative and rapid tool to prepare and evaluate a large number of new materials, saving time and expense for research and development. Considering that the activity and selectivity of catalysts depend on complex kinetic phenomena, making their development largely empirical in practice, they are prime candidates for combinatorial discovery and optimization. This review presents an overview of recent results of combinatorial screening of low-temperature fuel cell electrocatalysts for methanol oxidation. Optimum catalyst compositions obtained by combinatorial screening were compared with those of bulk catalysts, and the effect of the library geometry on the screening of catalyst composition is highlighted.

Review of Research Status and Development Trends of Wireless Passive LC Resonant Sensors for Harsh Environments.

PubMed

Li, Chen; Tan, Qiulin; Jia, Pinggang; Zhang, Wendong; Liu, Jun; Xue, Chenyang; Xiong, Jijun

2015-06-04

Measurement technology for various key parameters in harsh environments (e.g., high-temperature and biomedical applications) continues to be limited. Wireless passive LC resonant sensors offer long service life and can be suitable for harsh environments because they can transmit signals without battery power or wired connections. Consequently, these devices have become the focus of many current research studies. This paper addresses recent research, key technologies, and practical applications relative to passive LC sensors used to monitor temperature, pressure, humidity, and harmful gases in harsh environments. The advantages and disadvantages of various sensor types are discussed, and prospects and challenges for future development of these sensors are presented.

Arbitrary helicity control of circularly polarized light from lateral-type spin-polarized light-emitting diodes at room temperature

NASA Astrophysics Data System (ADS)

Nishizawa, Nozomi; Aoyama, Masaki; Roca, Ronel C.; Nishibayashi, Kazuhiro; Munekata, Hiro

2018-05-01

We demonstrate arbitrary helicity control of circularly polarized light (CPL) emitted at room temperature from the cleaved side facet of a lateral-type spin-polarized light-emitting diode (spin-LED) with two ferromagnetic electrodes in an antiparallel magnetization configuration. Driving alternate currents through the two electrodes results in polarization switching of CPL with frequencies up to 100 kHz. Furthermore, tuning the current density ratio in the two electrodes enables manipulation of the degree of circular polarization. These results demonstrate arbitrary electrical control of polarization with high speed, which is required for the practical use of lateral-type spin-LEDs as monolithic CPL light sources.

Review of Research Status and Development Trends of Wireless Passive LC Resonant Sensors for Harsh Environments

PubMed Central

Li, Chen; Tan, Qiulin; Jia, Pinggang; Zhang, Wendong; Liu, Jun; Xue, Chenyang; Xiong, Jijun

2015-01-01

Measurement technology for various key parameters in harsh environments (e.g., high-temperature and biomedical applications) continues to be limited. Wireless passive LC resonant sensors offer long service life and can be suitable for harsh environments because they can transmit signals without battery power or wired connections. Consequently, these devices have become the focus of many current research studies. This paper addresses recent research, key technologies, and practical applications relative to passive LC sensors used to monitor temperature, pressure, humidity, and harmful gases in harsh environments. The advantages and disadvantages of various sensor types are discussed, and prospects and challenges for future development of these sensors are presented. PMID:26053753

Rhodium(III)-Catalyzed Activation of C(sp3)-H Bonds and Subsequent Intermolecular Amidation at Room Temperature.

PubMed

Huang, Xiaolei; Wang, Yan; Lan, Jingbo; You, Jingsong

2015-08-03

Disclosed herein is a Rh(III)-catalyzed chelation-assisted activation of unreactive C(sp3)-H bonds, thus enabling an intermolecular amidation to provide a practical and step-economic route to 2-(pyridin-2-yl)ethanamine derivatives. Substrates with other N-donor groups are also compatible with the amidation. This protocol proceeds at room temperature, has a relatively broad functional-group tolerance and high selectivity, and demonstrates the potential of rhodium(III) in the promotive functionalization of unreactive C(sp3)-H bonds. A rhodacycle having a SbF6(-) counterion was identified as a plausible intermediate. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication of piezoelectric ceramic micro-actuator and its reliability for hard disk drives.

PubMed

Jing, Yang; Luo, Jianbin; Yang, Wenyan; Ju, Guoxian

2004-11-01

A new U-type micro-actuator for precisely positioning a magnetic head in high-density hard disk drives was proposed and developed. The micro-actuator is composed of a U-type stainless steel substrate and two piezoelectric ceramic elements. Using a high-d31 piezoelectric coefficient PMN-PZT ceramic plate and adopting reactive ion etching process fabricate the piezoelectric elements. Reliability against temperature was investigated to ensure the practical application to the drive products. The U-type substrate attached to each side via piezoelectric elements also was simulated by the finite-element method and practically measured by a laser Doppler vibrometer in order to testify the driving mechanics of it. The micro-actuator coupled with two piezoelectric elements featured large displacement of 0.875 microm and high-resonance frequency over 22 kHz. The novel piezoelectric micro-actuators then possess a useful compromise performance to displacement, resonance frequency, and generative force. The results reveal that the new design concept provides a valuable alternative for multilayer piezoelectric micro-actuators.

Novel process windows for enabling, accelerating, and uplifting flow chemistry.

PubMed

Hessel, Volker; Kralisch, Dana; Kockmann, Norbert; Noël, Timothy; Wang, Qi

2013-05-01

Novel Process Windows make use of process conditions that are far from conventional practices. This involves the use of high temperatures, high pressures, high concentrations (solvent-free), new chemical transformations, explosive conditions, and process simplification and integration to boost synthetic chemistry on both the laboratory and production scale. Such harsh reaction conditions can be safely reached in microstructured reactors due to their excellent transport intensification properties. This Review discusses the different routes towards Novel Process Windows and provides several examples for each route grouped into different classes of chemical and process-design intensification. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Non-switching to switching transferring mechanism investigation for Ag/SiO x /p-Si structure with SiO x deposited by HWCVD

NASA Astrophysics Data System (ADS)

Liu, Yanhong; Wang, Ruoying; Li, Zhongyue; Wang, Song; Huang, Yang; Peng, Wei

2018-04-01

We proposed and fabricated an Ag/SiO x /p-Si sandwich structure, in which amorphous SiO x films were deposited through hot wire chemical vapor deposition (HWCVD) using tetraethylorthosilicate (TEOS) as Si and O precursor. Experimental results indicate that the I–V properties of this structure transfer from non-switching to switching operation as the SiO x deposition temperature increased. The device with SiO x deposited at high deposition temperature exhibits typical bipolar switching properties, which can be potentially used in resistive switching random accessible memory (RRAM). The transferring mechanism from non-switching to switching can be ascribed to the change of structural and electronic properties of SiO x active layer deposited at different temperatures, as evidenced by analyzing FTIR spectrum and fitting its I–V characteristics curves. This work demonstrates a safe and practicable low-temperature device-grade SiO x film deposition technology by conducting HWCVD from TEOS.

Electrochemical Properties and Speciation in Mg(HMDS)2-Based Electrolytes for Magnesium Batteries as a Function of Ethereal Solvent Type and Temperature.

PubMed

Merrill, Laura C; Schaefer, Jennifer L

2017-09-19

Magnesium batteries are a promising alternative to lithium-ion batteries due to the widespread abundance of magnesium and its high specific volumetric energy capacity. Ethereal solvents such as tetrahydrofuran (THF) are commonly used for magnesium-ion electrolytes due to their chemical compatibility with magnesium metal, but the volatile nature of THF is a concern for practical application. Herein, we investigate magnesium bis(hexamethyldisilazide) plus aluminum chloride (Mg(HMDS) 2 -AlCl 3 ) electrolytes in THF, diglyme, and tetraglyme at varying temperature. We find that, despite the higher thermal stability of the glyme-based electrolytes, THF-based electrolytes have better reversibility at room temperature. Deposition/stripping efficiency is found to be a strong function of temperature. Diglyme-based Mg(HMDS) 2 -AlCl 3 electrolytes are found to not exchange as quickly as THF and tetraglyme, stabilizing AlCl 2 + and facilitating undesired aluminum deposition. Raman spectroscopy, 27 Al NMR, and mass spectrometry are used to identify solution speciation.

EXPERIMENTAL AND RESEARCH WORK IN NEUTRON DOSIMETRY. Final Summary Report for the Period May 15, 1959-June 15, 1960

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

Gorton, H.C.; Mengali, O.J.; Zacaroli, A.R.

A practical, prototype silicon p-n junction fast-neutron dosimeter, sensitive in the same range as human tissue, was developed, together with sn associated read-out circuit to facilitate the accurate measurement of accumulated dose. From both theoretical and experimental considerations, it was demonstrated that the dosimeter is essentially insensitive to the gamma and thermal components of a uranium fission spectrum. It was shown that accumulated damage effects appear to be environmentally stable up to an ambient temperature of 100 C. A rather raarked reversible temperature dependence of the read-out parameters requires either control of the read-out temperature or temperature compensation in themore » read-out device. A high degree of reproducibility of dosimeter characteristics from one device to another was not achieved. The lack of reproducibility was attributed to uncontrolled variables in the bulk silicon from which the devices are fabricated, and in the production procedure. (auth)« less

Stabilizing Superionic-Conducting Structures via Mixed-Anion Solid Solutions of Monocarba- closo -borate Salts

DOE PAGES

Tang, Wan Si; Yoshida, Koji; Soloninin, Alexei V.; ...

2016-09-01

Solid lithium and sodium closo-polyborate-based salts are capable of superionic conductivities surpassing even liquid electrolytes, but often only at above-ambient temperatures where their entropically driven disordered phases become stabilized. Here we show by X-ray diffraction, quasielastic neutron scattering, differential scanning calorimetry, NMR, and AC impedance measurements that by introducing 'geometric frustration' via the mixing of two different closo-polyborate anions, namely, 1-CB 9H 10- and CB 11H 12-, to form solid-solution anion-alloy salts of lithium or sodium, we can successfully suppress the formation of possible ordered phases in favor of disordered, fast-ion-conducting alloy phases over a broad temperature range from subambientmore » to high temperatures. Finally, this result exemplifies an important advancement for further improving on the remarkable conductive properties generally displayed by this class of materials and represents a practical strategy for creating tailored, ambient-temperature, solid, superionic conductors for a variety of upcoming all-solid-state energy devices of the future.« less

Life, performance and safety of Grace rechargeable lithium-titanium disulfide cells

NASA Astrophysics Data System (ADS)

Zuckerbrod, D.; Giovannoni, R. T.; Grossman, K. R.

The development of rechargeable Li-TiS2 cells is discussed. This proprietary process produces thin, flexible TiS2 cathodes with a life in excess of 500 cycles. TiS2 utilization of 93 percent is typically achieved at a C/5 discharge rate. A life of 200 cycles has been achieved for AA-size cells at a C/5 discharge rate and 60 cycles at the C rate. The practical energy density is 115 Wh/kg. Safety testing is underway. Vibration and high altitude did not cause venting. Crushing did not result in ignition or temperature rise. Forced overcharge and overdischarge did not result in skin temperatures above 40 C. The peak skin temperature during the short-circuit test was 120 C. Safety analyses point to the need for careful control of electrolyte volume and the benefits of a fusible separator. Grace is developing such a separator, which would shut down the electrochemical cell reaction at a temperature of 130 C.

H2O absorption spectroscopy for determination of temperature and H2O mole fraction in high-temperature particle synthesis systems.

PubMed

Torek, Paul V; Hall, David L; Miller, Tiffany A; Wooldridge, Margaret S

2002-04-20

Water absorption spectroscopy has been successfully demonstrated as a sensitive and accurate means for in situ determination of temperature and H2O mole fraction in silica (SiO2) particle-forming flames. Frequency modulation of near-infrared emission from a semiconductor diode laser was used to obtain multiple line-shape profiles of H2O rovibrational (v1 + v3) transitions in the 7170-7185-cm(-1) region. Temperature was determined by the relative peak height ratios, and XH2O was determined by use of the line-shape profiles. Measurements were made in the multiphase regions of silane/hydrogen/oxygen/ argon flames to verify the applicability of the diagnostic approach to combustion synthesis systems with high particle loadings. A range of equivalence ratios was studied (phi = 0.47 - 2.15). The results were compared with flames where no silane was present and with adiabatic equilibrium calculations. The spectroscopic results for temperature were in good agreement with thermocouple measurements, and the qualitative trends as a function of the equivalence ratio were in good agreement with the equilibrium predictions. The determinations for water mole fraction were in good agreement with theoretical predictions but were sensitive to the spectroscopic model parameters used to describe collisional broadening. Water absorption spectroscopy has substantial potential as a valuable and practical technology for both research and production combustion synthesis facilities.

White light upconversion emissions in Er3+/Tm3+/Yb3+ tridoped oxyfluoride glass

NASA Astrophysics Data System (ADS)

Guan, Xiaoping; Xu, Wei; Zhu, Shuang; Song, Qiutong; Wu, Xijun; Liu, Hailong

2015-10-01

Rare earth ions doped glasses producing visible upconversion emissions are of great interest due to their potential applications in the photonics filed. In fact, practical application of upconversion emissions has been used to obtain color image displays and white light sources. However, there are few reports on the thermal effect on tuning the emission color of the RE doped materials. In this work, the Er3+/Tm3+/Yb3+ tridoped oxyfluoride glasses were prepared through high temperature solid-state method. Under a 980 nm diode laser excitation, the upconversion emissions from the samples were studied. At room-temperature, bright white luminescence, whose CIE chromaticity coordinate was about (0.28, 0.31), can be obtained when the excitation power was 120 mW. The emission color was changed by varying the intensity ratios between RGB bands, which are strongly dependent on the rare earth ions concentration. The temperature dependent color emissions were also investigated. As temperature increased, the intensities for the emission bands presented different decay rates, finally resulting in the changing of the CIE coordinate. When the temperature was 573 K, white light with color coordinate of (0.31, 0.33) was achieved, which matches well with the white reference (0.33, 0.33). The color tunability, high quality of white light and intense emission intensity make the transparent oxyfluoride glasses excellent candidates for applications in solid-state lighting.

Optical ray tracing method for simulating beam-steering effects during laser diagnostics in turbulent media.

PubMed

Wang, Yejun; Kulatilaka, Waruna D

2017-04-10

In most coherent spectroscopic methods used in gas-phase laser diagnostics, multiple laser beams are focused and crossed at a specific location in space to form the probe region. The desired signal is then generated as a result of nonlinear interactions between the beams in this overlapped region. When such diagnostic schemes are implemented in practical devices having turbulent reacting flow fields with refractive index gradients, the resulting beam steering can give rise to large measurement uncertainties. The objective of this work is to simulate beam-steering effects arising from pressure and temperature gradients in gas-phase media using an optical ray tracing approach. The ZEMAX OpticStudio software package is used to simulate the beam crossing and uncrossing effects in the presence of pressure and temperature gradients, specifically the conditions present in high-pressure, high-temperature combustion devices such as gas turbine engines. Specific cases involving two-beam and three-beam crossing configurations are simulated. The model formulation, the effects of pressure and temperature gradients, and the resulting beam-steering effects are analyzed. The results show that thermal gradients in the range of 300-3000 K have minimal effects, while pressure gradients in the range of 1-50 atm result in pronounced beam steering and the resulting signal fluctuations in the geometries investigated. However, with increasing pressures, the temperature gradients can also have a pronounced effect on the resultant signal levels.

Lower critical solution temperature (LCST) phase separation of glycol ethers for forward osmotic control.

PubMed

Nakayama, Daichi; Mok, Yeongbong; Noh, Minwoo; Park, Jeongseon; Kang, Sunyoung; Lee, Yan

2014-03-21

Lower critical solution temperature (LCST) phase transition of glycol ether (GE)-water mixtures induces an abrupt change in osmotic pressure driven by a mild temperature change. The temperature-controlled osmotic change was applied for the forward osmosis (FO) desalination. Among three GEs evaluated, di(ethylene glycol) n-hexyl ether (DEH) was selected as a potential FO draw solute. A DEH-water mixture with a high osmotic pressure could draw fresh water from a high-salt feed solution such as seawater through a semipermeable membrane at around 10 °C. The water-drawn DEH-water mixture was phase-separated into a water-rich phase and a DEH-rich phase at around 30 °C. The water-rich phase with a much reduced osmotic pressure released water into a low-salt solution, and the DEH-rich phase was recovered into the initial DEH-water mixture. The phase separation behaviour, the residual GE concentration in the water-rich phase, the osmotic pressure of the DEH-water mixture, and the osmotic flux between the DEH-water mixture and salt solutions were carefully analysed for FO desalination. The liquid-liquid phase separation of the GE-water mixture driven by the mild temperature change between 10 °C and 30 °C is very attractive for the development of an ideal draw solute for future practical FO desalination.

Parameter Calibration of GTN Damage Model and Formability Analysis of 22MnB5 in Hot Forming Process

NASA Astrophysics Data System (ADS)

Ying, Liang; Liu, Wenquan; Wang, Dantong; Hu, Ping

2017-11-01

Hot forming of high strength steel at elevated temperatures is an attractive technology to achieve the lightweight of vehicle body. The mechanical behavior of boron steel 22MnB5 strongly depends on the variation of temperature which makes the process design more difficult. In this paper, the Gurson-Tvergaard-Needleman (GTN) model is used to study the formability of 22MnB5 sheet at different temperatures. Firstly, the rheological behavior of 22MnB5 is analyzed through a series of hot tensile tests at a temperature range of 600-800 °C. Then, a detailed process to calibrate the damage parameters is given based on the response surface methodology and genetic algorithm method. The GTN model together with the damage parameters calibrated is then implemented to simulate the deformation and damage evolution of 22MnB5 in the process of high-temperature Nakazima test. The capability of the GTN model as a suitable tool to evaluate the sheet formability is confirmed by comparing experimental and calculated results. Finally, as a practical application, the forming limit diagram of 22MnB5 at 700 °C is constructed using the Nakazima simulation and Marciniak-Kuczynski (M-K) model, respectively. And the simulation integrated GTN model shows a higher reliability by comparing the predicted results of these two approaches with the experimental ones.

Research on Vehicle Temperature Regulation System Based on Air Convection Principle

NASA Astrophysics Data System (ADS)

Zhuge, Muzi; Li, Xiang; Liang, Caifeng

2018-03-01

The long time parking outdoors in the summer will lead to too high temperature in the car, and the harmful gas produced by the vehicle engine will stay in the confined space for a long time during the parking process, which will do great harm to the human body. If the air conditioning system is turned on before driving, the cooling rate is slow and the battery loss is large. To solve the above problems, we designed a temperature adjusting system based on the principle of air convection. We can choose the automatic mode or manual mode to achieve control of a convection window. In the automatic mode, the system will automatically detect the environmental temperature, through the sensor to complete the detection, and the signal is transmitted to the microcontroller to control the window open or close, in manual mode, the remote control of the window can be realized by Bluetooth. Therefore, the system has important practical significance to effectively regulate temperature, prolong battery life, and improve the safety and comfort of traffic vehicles.

Power enhancement of piezoelectric transformers by adding heat transfer equipment.

PubMed

Su, Yu-Hao; Liu, Yuan-Ping; Vasic, Dejan; Wu, Wen-Jong; Costa, François; Lee, Chih-Kung

2012-10-01

It is known that piezoelectric transformers have several inherent advantages compared with conventional electromagnetic transformers. However, the maximum power capacity of piezoelectric transformers is not as large as electromagnetic transformers in practice, especially in the case of high output current. The theoretical power density of piezoelectric transformers calculated by stress boundary can reach 330 W/cm(3), but no piezoelectric transformer has ever reached such a high power density in practice. The power density of piezoelectric transformers is limited to 33 W/cm(3) in practical applications. The underlying reason is that the maximum passing current of the piezoelectric material (mechanical current) is limited by the temperature rise caused by heat generation. To increase this current and the power capacity, we proposed to add a thermal pad to the piezoelectric transformer to dissipate heat. The experimental results showed that the proposed techniques can increase by 3 times the output current of the piezoelectric transformer. A theoretical-phenomenological model which explains the relationship between vibration velocity and generated heat is also established to verify the experimental results.

Effects of Climatic Conditions and Management Practices on Agricultural Carbon and Water Budgets in the Inland Pacific Northwest USA

NASA Astrophysics Data System (ADS)

Chi, Jinshu; Waldo, Sarah; Pressley, Shelley N.; Russell, Eric S.; O'Keeffe, Patrick T.; Pan, William L.; Huggins, David R.; Stöckle, Claudio O.; Brooks, Erin S.; Lamb, Brian K.

2017-12-01

Cropland is an important land cover influencing global carbon and water cycles. Variability of agricultural carbon and water fluxes depends on crop species, management practices, soil characteristics, and climatic conditions. In the context of climate change, it is critical to quantify the long-term effects of these environmental drivers and farming activities on carbon and water dynamics. Twenty site-years of carbon and water fluxes covering a large precipitation gradient and a variety of crop species and management practices were measured in the inland Pacific Northwest using the eddy covariance method. The rain-fed fields were net carbon sinks, while the irrigated site was close to carbon neutral during the winter wheat crop years. Sites growing spring crops were either carbon sinks, sources, or neutral, varying with crops, rainfall zones, and tillage practices. Fluxes were more sensitive to variability in precipitation than temperature: annual carbon and water fluxes increased with the increasing precipitation while only respiration increased with temperature in the high-rainfall area. Compared to a nearby rain-fed site, irrigation improved winter wheat production but resulted in large losses of carbon and water to the atmosphere. Compared to conventional tillage, no-till had significantly lower respiration but resulted in slightly lower yields and water use efficiency over 4 years. Under future climate change, it is expected that more carbon fixation by crops and evapotranspiration would occur in a warmer and wetter environment.

Serial and parallel power equipment with high-temperature superconducting elements

NASA Technical Reports Server (NTRS)

Bencze, Laszlo; Goebl, Nandor; Palotas, Bela; Vajda, Istvan

1995-01-01

One of the prospective, practical applications of high-temperature superconductors is the fault-current limitation in electrical energy networks. The development and testing of experimental HTSC serial current limiters have been reported in the literature. A Hungarian electric power company has proposed the development of a parallel equipment for arc suppressing both in the industrial and customers' networks. On the basis of the company's proposal the authors have outlined the scheme of a compound circuit that can be applied both for current limitation and arc suppressing. In this paper the design principles and methods of the shunt equipment are presented. These principles involve the electrical, mechanical and cryogenic aspects with the special view on the electrical and mechanical connection between the HTSC material and the current lead. Preliminary experiments and tests have been carried out to demonstrate the validity of the design principles developed. The results of the experiments and of the technological investigations are presented.

Broadband near-field infrared spectroscopy with a high temperature plasma light source.

PubMed

Lahneman, D J; Huffman, T J; Xu, Peng; Wang, S L; Grogan, T; Qazilbash, M M

2017-08-21

Scattering-type scanning near-field optical microscopy (S-SNOM) has enormous potential as a spectroscopy tool in the infrared spectral range where it can probe phonon resonances and carrier dynamics at the nanometer lengths scales. However, its applicability is limited by the lack of practical and affordable table-top light sources emitting intense broadband infrared radiation in the 100 cm -1 to 2,500 cm -1 spectral range. This paper introduces a high temperature plasma light source that is both ultra-broadband and has much more radiant power in the infrared spectral range than conventional, table-top thermal light sources such as the globar. We implement this plasma lamp in our near-field optical spectroscopy set up and demonstrate its capability as a broadband infrared nano-spectroscopy light source by obtaining near-field infrared amplitude and phase spectra of the phonon resonances of SiO 2 and SrTiO 3 .

High Tensile Strength Amalgams for In-Space Fabrication and Repair

NASA Technical Reports Server (NTRS)

Grugel, Richard N.

2006-01-01

Amalgams are well known for their use in dental practice as a tooth filling material. They have a number of useful attributes that include room temperature fabrication, corrosion resistance, dimensional stability, and very good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits other potential applications. Improved material properties (strength and temperature) of amalgams may have application to the freeform fabrication of repairs or parts that might be necessary during an extended space mission. Advantages would include, but are not limited to: the ability to produce complex parts, a minimum number of processing steps, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption. The work presented here shows how the properties of amalgams can be improved by changing particle geometries in conjunction with novel engineering metals.

Ultralong room temperature phosphorescence from amorphous organic materials toward confidential information encryption and decryption.

PubMed

Su, Yan; Phua, Soo Zeng Fiona; Li, Youbing; Zhou, Xianju; Jana, Deblin; Liu, Guofeng; Lim, Wei Qi; Ong, Wee Kong; Yang, Chaolong; Zhao, Yanli

2018-05-01

Ultralong room temperature phosphorescence (URTP) emitted from pure amorphous organic molecules is very rare. Although a few crystalline organic molecules could realize URTP with long lifetimes (>100 ms), practical applications of these crystalline organic phosphors are still challenging because the formation and maintenance of high-quality crystals are very difficult and complicated. Herein, we present a rational design for minimizing the vibrational dissipation of pure amorphous organic molecules to achieve URTP. By using this strategy, a series of URTP films with long lifetimes and high phosphorescent quantum yields (up to 0.75 s and 11.23%, respectively) were obtained from amorphous organic phosphors without visible fluorescence and phosphorescence under ambient conditions. On the basis of the unique features of URTP films, a new green screen printing technology without using any ink was developed toward confidential information encryption and decryption. This work presents a breakthrough strategy in applying amorphous organic materials for URTP.

The Influence of Al4C3 Nanoparticles on the Physical and Mechanical Properties of Metal Matrix Composites at High Temperatures

NASA Astrophysics Data System (ADS)

Vorozhtsov, S.; Kolarik, V.; Promakhov, V.; Zhukov, I.; Vorozhtsov, A.; Kuchenreuther-Hummel, V.

2016-05-01

Metal matrix composites (MMC) based on aluminum and reinforced with nonmetallic particles are of great practical interest due to their potentially high physico-mechanical properties. In this work, Al-Al4C3 composites were obtained by a hot-compacting method. Introduction of nanodiamonds produced by detonation to the Al powder in an amount of 10 wt.% led to the formation of ~15 wt.% of aluminum carbide during hot compacting. It was found that composite materials with the diamond content of 10 wt.% in the initial powder mix have an average microhardness of 1550 MPa, whilst the similarly compacted aluminum powder without reinforcing particles shows a hardness of 750 MPa. The mechanical properties of an Al-Al4C3 MMC at elevated test temperatures exceeded those of commercial casting aluminum alloys such as A356.

Comprehensive comparison of the levitation performance of bulk YBaCuO arrays above two different types of magnetic guideways

NASA Astrophysics Data System (ADS)

Deng, Zigang; Qian, Nan; Che, Tong; Jin, Liwei; Si, Shuaishuai; Zhang, Ya; Zheng, Jun

2016-12-01

The permanent magnet guideway (PMG) is an important part of high temperature superconducting (HTS) maglev systems. So far, two types of PMG, the normal PMG and Halbach-type PMG, are widely applied in present maglev transportation systems. In this paper, the levitation performance of high temperature superconductor bulks above the two PMGs was synthetically compared. Both static levitation performance and dynamic response characteristics were investigated. Benefiting from the reasonable magnetic field distribution, the Halbach-type PMG is able to gain larger levitation force, greater levitation force decay during the same relaxation time, bigger resonance frequency and dynamic stiffness for the bulk superconductor levitation unit compared with the normal PMG. Another finding is that the Halbach-type PMG is not sensitive to the levitation performance of the bulk levitation unit with different arrays. These results are helpful for the practical application of HTS maglev systems.

Thermoelectricity for future sustainable energy technologies

NASA Astrophysics Data System (ADS)

Weidenkaff, Anke

2017-07-01

Thermoelectricity is a general term for a number of effects describing the direct interconversion of heat and electricity. Thermoelectric devices are therefore promising, environmental-friendly alternatives to conventional power generators or cooling units. Since the mid-90s, research on thermoelectric properties and their applications has steadily increased. In the course of years, the development of high-temperature resistant TE materials and devices has emerged as one of the main areas of interest focusing both on basic research and practical applications. A wide range of innovative and cost-efficient material classes has been studied and their properties improved. This has also led to advances in synthesis and metrology. The paper starts out with thermoelectric history, basic effects underlying thermoelectric conversion and selected examples of application. The main part focuses on thermoelectric materials including an outline of the design rules, a review on the most common materials and the feasibility of improved future high-temperature thermoelectric converters.

Modeling of subcooling and solidification of phase change materials

NASA Astrophysics Data System (ADS)

Günther, Eva; Mehling, Harald; Hiebler, Stefan

2007-12-01

Phase change materials (PCM) are able to store thermal energy in small temperature intervals very efficiently due to their high latent heat. Particularly high storage capacity is found in salt hydrates. Salt hydrates however often show subcooling, thus inhibiting the release of the stored heat. In the state of the art simulations of PCM, the effect of subcooling is almost always neglected. This is a practicable approach for small subcooling, but it is problematic for subcooling in the order of the driving temperature gradient on unloading the storage. In this paper, we first present a new algorithm to simulate subcooling in a physically proper way. Then, we present a parametric study to demonstrate the main features of the algorithm and a comparison of computed and experimentally obtained data. The new algorithm should be particularly useful in simulating applications with low cooling rates, for example building applications.

Fiber Fabry-Perot tip sensor based on multimode photonic crystal fiber

NASA Astrophysics Data System (ADS)

Wu, Di; Huang, Yu; Fu, Jian-Yu; Wang, Guo-Yin

2015-03-01

We propose a novel Fabry-Perot interferometer (FPI) sensor for simultaneous measurement of refractive index (RI) and temperature based on Fresnel reflection and the thermo-optic effect of silica. The sensor head consists of a short section of multimode photonic crystal fiber (MPCF) and a conventional single mode fiber (SMF), where two thin films are formed by collapsing the air holes of MPCF with a commercialized fusion splicer. Experimental results show that such a device has a linear RI sensitivity of ~21.52 dB/RIU (RI unit) and a linear optical path difference (OPD) temperature sensitivity of ~25 nm/°C. In addition, a high RI resolution of about ~1.7×10-5 is obtained by using the Fourier transformation to decompose the spectral response in different spatial frequencies. Low-cost, easy fabrication and high resolution make it appropriate for practical applications.

Microalloying Ultrafine Grained Al Alloys with Enhanced Ductility

PubMed Central

Jiang, L.; Li, J. K.; Cheng, P. M.; Liu, G.; Wang, R. H.; Chen, B. A.; Zhang, J. Y.; Sun, J.; Yang, M. X.; Yang, G.

2014-01-01

Bulk ultrafine grained (UFG)/nanocrystal metals possess exceptional strength but normally poor ductility and thermal stability, which hinder their practical applications especially in high-temperature environments. Through microalloying strategy that enables the control of grains and precipitations in nanostructured regime, here we design and successfully produce a highly microstructure-stable UFG Al-Cu-Sc alloy with ~275% increment in ductility and simultaneously ~50% enhancement in yield strength compared with its Sc-free counterpart. Although the precipitations in UFG alloys are usually preferentially occurred at grain boundaries even at room temperature, minor Sc addition into the UFG Al-Cu alloys is found to effectively stabilize the as-processed microstructure, strongly suppress the θ-Al2Cu phase precipitation at grain boundary, and remarkably promote the θ′-Al2Cu nanoparticles dispersed in the grain interior in artificial aging. A similar microalloying strategy is expected to be equally effective for other UFG heat-treatable alloys. PMID:24398915

A Smart High Accuracy Silicon Piezoresistive Pressure Sensor Temperature Compensation System

PubMed Central

Zhou, Guanwu; Zhao, Yulong; Guo, Fangfang; Xu, Wenju

2014-01-01

Theoretical analysis in this paper indicates that the accuracy of a silicon piezoresistive pressure sensor is mainly affected by thermal drift, and varies nonlinearly with the temperature. Here, a smart temperature compensation system to reduce its effect on accuracy is proposed. Firstly, an effective conditioning circuit for signal processing and data acquisition is designed. The hardware to implement the system is fabricated. Then, a program is developed on LabVIEW which incorporates an extreme learning machine (ELM) as the calibration algorithm for the pressure drift. The implementation of the algorithm was ported to a micro-control unit (MCU) after calibration in the computer. Practical pressure measurement experiments are carried out to verify the system's performance. The temperature compensation is solved in the interval from −40 to 85 °C. The compensated sensor is aimed at providing pressure measurement in oil-gas pipelines. Compared with other algorithms, ELM acquires higher accuracy and is more suitable for batch compensation because of its higher generalization and faster learning speed. The accuracy, linearity, zero temperature coefficient and sensitivity temperature coefficient of the tested sensor are 2.57% FS, 2.49% FS, 8.1 × 10−5/°C and 29.5 × 10−5/°C before compensation, and are improved to 0.13%FS, 0.15%FS, 1.17 × 10−5/°C and 2.1 × 10−5/°C respectively, after compensation. The experimental results demonstrate that the proposed system is valid for the temperature compensation and high accuracy requirement of the sensor. PMID:25006998

P-Type Transparent Cu-Alloyed ZnS Deposited at Room Temperature

DOE PAGES

Woods-Robinson, Rachel; Cooper, Jason K.; Xu, Xiaojie; ...

2016-03-16

All transparent conducting materials (TCMs) of technological practicality are n-type; the inferior conductivity of p-type TCMs has limited their adoption. Additionally, many relatively high-performing p-type TCMs require synthesis temperatures > 400 °C. Here, room-temperature pulsed laser deposition of copper-alloyed zinc sulfide (Cu x Zn 1- x S) thin films (0 ≤ x ≤ 0.75) is reported. For 0.09 ≤ x ≤ 0.35, Cu x Zn 1- x S has high p-type conductivity, up to 42 S cm -1 at x = 0.30, with an optical band gap tunable from ≈3.0–3.3 eV and transparency, averaged over the visible, of 50%–71% formore » 200–250 nm thick films. In this range, synchrotron X-ray and electron diffraction reveal a nanocrystalline ZnS structure. Secondary crystalline Cu y S phases are not observed, and at higher Cu concentrations, x > 0.45, films are amorphous and poorly conducting. Furthermore, within the TCM regime, the conductivity is temperature independent, indicating degenerate hole conduction. A decrease in lattice parameter with Cu content suggests that the hole conduction is due to substitutional incorporation of Cu onto Zn sites. This hole-conducting phase is embedded in a less conducting amorphous Cu y S, which dominates at higher Cu concentrations. Finally, the combination of high hole conductivity and optical transparency for the peak conductivity Cu x Zn 1- x S films is among the best reported to date for a room temperature deposited p-type TCM.« less

Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

NASA Astrophysics Data System (ADS)

Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

2018-04-01

Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

2013-12-01

Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

PubMed Central

Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

2013-01-01

Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications. PMID:24346481

Seed storage at elevated partial pressure of oxygen, a fast method for analysing seed ageing under dry conditions.

PubMed

Groot, S P C; Surki, A A; de Vos, R C H; Kodde, J

2012-11-01

Despite differences in physiology between dry and relative moist seeds, seed ageing tests most often use a temperature and seed moisture level that are higher than during dry storage used in commercial practice and gene banks. This study aimed to test whether seed ageing under dry conditions can be accelerated by storing under high-pressure oxygen. methods: Dry barley (Hordeum vulgare), cabbage (Brassica oleracea), lettuce (Lactuca sativa) and soybean (Glycine max) seeds were stored between 2 and 7 weeks in steel tanks under 18 MPa partial pressure of oxygen. Storage under high-pressure nitrogen gas or under ambient air pressure served as controls. The method was compared with storage at 45 °C after equilibration at 85 % relative humidity and long-term storage at the laboratory bench. Germination behaviour, seedling morphology and tocopherol levels were assessed. The ageing of the dry seeds was indeed accelerated by storing under high-pressure oxygen. The morphological ageing symptoms of the stored seeds resembled those observed after ageing under long-term dry storage conditions. Barley appeared more tolerant of this storage treatment compared with lettuce and soybean. Less-mature harvested cabbage seeds were more sensitive, as was the case for primed compared with non-primed lettuce seeds. Under high-pressure oxygen storage the tocopherol levels of dry seeds decreased, in a linear way with the decline in seed germination, but remained unchanged in seeds deteriorated during storage at 45 °C after equilibration at 85 % RH. Seed storage under high-pressure oxygen offers a novel and relatively fast method to study the physiology and biochemistry of seed ageing at different seed moisture levels and temperatures, including those that are representative of the dry storage conditions as used in gene banks and commercial practice.

Synthesis of single-walled carbon nanotubes and graphene composite in arc for ultracapacitors

NASA Astrophysics Data System (ADS)

Li, Jian; Cheng, Xiaoqian; Shashurin, Alexey; Keidar, Michael

2012-10-01

Arc discharge supported by the erosion of graphite anode is considered as one of the most practical and efficient methods to synthesize various carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene with minimal defects and large yield due to the relatively high synthesis temperature and eco-friendly growth mechanism. By introducing a non-uniform magnetic field during synthesis process, large-scale graphene and high-purity SWCNT can be obtained in one step. In addition, the yield of graphene can be controlled by external parameters, such as the type and pressure of buffer gas, the temperature of substrate, and so on. Possessing the properties of highly accessible surface area and good electrical conductivity, the composite of graphene and SWCNT are promising nanomaterials for the electrodes of ultracapacitor, which can store electric energy with high level of capacitance. In this work, we fabricated electrodes of ultracapacitor based on nanostructures composite by wire-wound rod coating method, characterized them by SEM, EDX and Raman spectroscopy, and tested the performance by a potentiostat/galvanostat.

Development of practical high temperature superconducting wire for electric power application

NASA Technical Reports Server (NTRS)

Hawsey, Robert A.; Sokolowski, Robert S.; Haldar, Pradeep; Motowidlo, Leszek R.

1995-01-01

The technology of high temperature superconductivity has gone from beyond mere scientific curiousity into the manufacturing environment. Single lengths of multifilamentary wire are now produced that are over 200 meters long and that carry over 13 amperes at 77 K. Short-sample critical current densities approach 5 x 104 A/sq cm at 77 K. Conductor requirements such as high critical current density in a magnetic field, strain-tolerant sheathing materials, and other engineering properties are addressed. A new process for fabricating round BSCCO-2212 wire has produced wires with critical current densities as high as 165,000 A/sq cm at 4.2 K and 53,000 A/sq cm at 40 K. This process eliminates the costly, multiple pressing and rolling steps that are commonly used to develop texture in the wires. New multifilamentary wires with strengthened sheathing materials have shown improved yield strengths up to a factor of five better than those made with pure silver. Many electric power devices require the wire to be formed into coils for production of strong magnetic fields. Requirements for coils and magnets for electric power applications are described.

Smart Pd Catalyst with Improved Thermal Stability Supported on High-Surface-Area LaFeO3 Prepared by Atomic Layer Deposition.

PubMed

Onn, Tzia Ming; Monai, Matteo; Dai, Sheng; Fonda, Emiliano; Montini, Tiziano; Pan, Xiaoqing; Graham, George W; Fornasiero, Paolo; Gorte, Raymond J

2018-04-11

The concept of self-regenerating or "smart" catalysts, developed to mitigate the problem of supported metal particle coarsening in high-temperature applications, involves redispersing large metal particles by incorporating them into a perovskite-structured support under oxidizing conditions and then exsolving them as small metal particles under reducing conditions. Unfortunately, the redispersion process does not appear to work in practice because the surface areas of the perovskite supports are too low and the diffusion lengths for the metal ions within the bulk perovskite too short. Here, we demonstrate reversible activation upon redox cycling for CH 4 oxidation and CO oxidation on Pd supported on high-surface-area LaFeO 3 , prepared as a thin conformal coating on a porous MgAl 2 O 4 support using atomic layer deposition. The LaFeO 3 film, less than 1.5 nm thick, was shown to be initially stable to at least 900 °C. The activated catalysts exhibit stable catalytic performance for methane oxidation after high-temperature treatment.

Urine temperature as an index for the core temperature of industrial workers in hot or cold environments

NASA Astrophysics Data System (ADS)

Kawanami, Shoko; Horie, Seichi; Inoue, Jinro; Yamashita, Makiko

2012-11-01

Workers working in hot or cold environments are at risk for heat stroke and hypothermia. In Japan, 1718 people including 47 workers died of heat stroke in 2010 (Ministry of Health Labour and Welfare, Japan 2011). While the American Conference of Governmental Industrial Hygienists (ACGIH) recommendation lists the abnormal core temperature of workers as a criterion for halting work, no method has been established for reliably measuring core temperatures at workplaces. ISO 9886 (Ergonomics-evaluation of thermal strain by physiological measurements. ISO copyright office, Geneva, pp 3-14; 2004) recognizes urine temperature as an index of core temperature only at normal temperature. In this study we ascertained whether or not urine temperature could serve as an index for core temperature at temperatures above and below the ISO range. We measured urine temperature of 31 subjects (29.8 ± 11.9 years) using a thermocouple sensor placed in the toilet bowl at ambient temperature settings of 40, 20, and 5˚C, and compared them with rectal temperature. At all ambient temperature settings, urine temperature correlated closely with rectal temperature exhibiting small mean bias. Urine temperature changed in a synchronized manner with rectal temperature at 40˚C. A Bland and Altman analysis showed that the limits of agreement (mean bias ± 2SD) between rectal and urine temperatures were -0.39 to +0.15˚C at 40˚C (95%CI -0.44 to +0.20˚C) and -0.79 to +0.29˚C at 5˚C (-0.89 to +0.39˚C). Hence, urine temperature as measured by the present method is a practical surrogate index for rectal temperature and represents a highly reliable biological monitoring index for assessing hot and cold stresses of workers at actual workplaces.

Advanced Thermal Storage for Central Receivers with Supercritical Coolants

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

Kelly, Bruce D.

2010-06-15

The principal objective of the study is to determine if supercritical heat transport fluids in a central receiver power plant, in combination with ceramic thermocline storage systems, offer a reduction in levelized energy cost over a baseline nitrate salt concept. The baseline concept uses a nitrate salt receiver, two-tank (hot and cold) nitrate salt thermal storage, and a subcritical Rankine cycle. A total of 6 plant designs were analyzed, as follows: Plant Designation Receiver Fluid Thermal Storage Rankine Cycle Subcritical nitrate salt Nitrate salt Two tank nitrate salt Subcritical Supercritical nitrate salt Nitrate salt Two tank nitrate salt Supercritical Lowmore » temperature H2O Supercritical H2O Two tank nitrate salt Supercritical High temperature H2O Supercritical H2O Packed bed thermocline Supercritical Low temperature CO2 Supercritical CO2 Two tank nitrate salt Supercritical High temperature CO2 Supercritical CO2 Packed bed thermocline Supercritical Several conclusions have been drawn from the results of the study, as follows: 1) The use of supercritical H2O as the heat transport fluid in a packed bed thermocline is likely not a practical approach. The specific heat of the fluid is a strong function of the temperatures at values near 400 °C, and the temperature profile in the bed during a charging cycle is markedly different than the profile during a discharging cycle. 2) The use of supercritical CO2 as the heat transport fluid in a packed bed thermocline is judged to be technically feasible. Nonetheless, the high operating pressures for the supercritical fluid require the use of pressure vessels to contain the storage inventory. The unit cost of the two-tank nitrate salt system is approximately $24/kWht, while the unit cost of the high pressure thermocline system is nominally 10 times as high. 3) For the supercritical fluids, the outer crown temperatures of the receiver tubes are in the range of 700 to 800 °C. At temperatures of 700 °C and above, intermetallic compounds can precipitate between, and within, the grains of nickel alloys. The precipitation leads to an increase in tensile strength, and a decrease in ductility. Whether the proposed tube materials can provide the required low cycle fatigue life for the supercritical H2O and CO2 receivers is an open question. 4) A ranking of the plants, in descending order of technical and economic feasibility, is as follows: i) Supercritical nitrate salt and baseline nitrate salt: equal ratings ii) Low temperature supercritical H2O iii) Low temperature supercritical CO2 iv) High temperature supercritical CO2 v) High temperature supercritical H2O 5) The two-tank nitrate salt thermal storage systems are strongly preferred over the thermocline systems using supercritical heat transport fluids.« less

Computational design and refinement of self-heating lithium ion batteries

NASA Astrophysics Data System (ADS)

Yang, Xiao-Guang; Zhang, Guangsheng; Wang, Chao-Yang

2016-10-01

The recently discovered self-heating lithium ion battery has shown rapid self-heating from subzero temperatures and superior power thereafter, delivering a practical solution to poor battery performance at low temperatures. Here, we describe and validate an electrochemical-thermal coupled model developed specifically for computational design and improvement of the self-heating Li-ion battery (SHLB) where nickel foils are embedded in its structure. Predicting internal cell characteristics, such as current, temperature and Li-concentration distributions, the model is used to discover key design factors affecting the time and energy needed for self-heating and to explore advanced cell designs with the highest self-heating efficiency. It is found that ohmic heat generated in the nickel foil accounts for the majority of internal heat generation, resulting in a large internal temperature gradient from the nickel foil toward the outer cell surface. The large through-plane temperature gradient leads to highly non-uniform current distribution, and more importantly, is found to be the decisive factor affecting the heating time and energy consumption. A multi-sheet cell design is thus proposed and demonstrated to substantially minimize the temperature gradient, achieving 30% more rapid self-heating with 27% less energy consumption than those reported in the literature.

The effect of cool water ingestion on gastrointestinal pill temperature.

PubMed

Wilkinson, David M; Carter, James M; Richmond, Victoria L; Blacker, Sam D; Rayson, Mark P

2008-03-01

Telemetric gastrointestinal (GI) temperature pills are now commonly used to measure core body temperature and could minimize the risk of heat illness while maximizing operational effectiveness in workers subject to high levels of thermal strain. To quantify the effect of repeated cool water ingestion on the accuracy of GI pill temperature. Ten operational firefighters ingested a pill to measure GI temperature (T1int) before overnight sleep. Two hours following breakfast and 11.5 h after ingesting T1int, the firefighters ingested a second pill (T2int) before performing 8.5 h of intermittent activity (repetitive cycles of 30 min of seated rest followed by 30 min of general firefighter duties). During the first 2 min of each 30-min rest period, the firefighters consumed 250 mL of chilled water (5-8 degrees C). Water ingestion had a highly variable effect both within and between subjects in transiently (32 +/- 10 min) reducing the temperature of T2int in comparison with T1int. In general, this transient reduction in T2int became progressively smaller as time following ingestion increased. In some firefighters, the difference between T1int and T2int became negligible (+/- 0.1 degrees C) after 3 h, whereas in two others, large differences (peaking at 2.0 degrees C and 6.3 degrees C) were still observed when water was consumed 8 h after pill ingestion. These results show that a GI pill ingested immediately prior to physical activity cannot be used to measure core body temperature accurately in all individuals during the following 8 h when cool fluids are regularly ingested. This makes GI temperature measurement unsuitable for workers who respond to emergency deployments when regular fluid consumption is recommended operational practice.

Solar Array at Very High Temperatures: Ground Tests

NASA Technical Reports Server (NTRS)

Vayner, Boris

2016-01-01

Solar array design for any spacecraft is determined by the orbit parameters. For example, operational voltage for spacecraft in Low Earth Orbit (LEO) is limited by significant differential charging due to interactions with low temperature plasma. In order to avoid arcing in LEO, solar array is designed to generate electrical power at comparatively low voltages (below 100 V) or to operate at higher voltages with encapsulated of all suspected discharge locations. In Geosynchronous Orbit (GEO) differential charging is caused by energetic electrons that produce differential potential between coverglass and conductive spacecraft body in a kilovolt range. In such a case, weakly conductive layer over coverglass (ITO) is one of possible measures to eliminate dangerous discharges on array surface. Temperature variations for solar arrays in both orbits are measured and documented within the range of -150 C +110 C. This wide interval of operational temperatures is regularly reproduced in ground tests with radiative heating and cooling inside shroud with flowing liquid nitrogen. The requirements to solar array design and tests turn out to be more complicated when planned trajectory crosses these two orbits and goes closer to Sun. Conductive layer over coverglass causes sharp increase in parasitic current collected from LEO plasma, high temperature may cause cracks in encapsulating material (RTV), radiative heating of coupon in vacuum chamber becomes practically impossible above 150 C, conductivities of glass and adhesive go up with temperature that decrease array efficiency, and mechanical stresses grow up to critical magnitudes. A few test arrangements and respective results are presented in current paper. Coupons were tested against arcing in simulated LEO and GEO environments under elevated temperatures up to 200 C. The dependence of leakage current on temperature was measured, and electrostatic cleanness was verified for coupons with antireflection (AR) coating over ITO layer.

Disent to Pairing Mechanism

NASA Astrophysics Data System (ADS)

Cheng, Kaijia; Cheng, Shuyu

Up to now, the pairing mechanism is regarded as the rule of thumb criterion of an acceptable theory of superconductivity. It is generally held as a taboo for any theory which is not founded on this basis. However this is not true and it misleads the direction for the theoretical research for both the high and low temperature regions and eventually delays the progress in practice. It is now the time to clear up the situation.

The Design and Testing of a High-Temperature Graphite Dilatometer

DTIC Science & Technology

1992-06-24

characterization of its CTE is of little significance. Practical candidates are silica (fused quartz glass), Zerodur -type glass ceramics (5 x 10- 8 C-1 ), and...titanium silicates (< 5 x IO17 *C-1 ). Partially crystallized glasses, such as Zerodur , are limited to about 6006C. Silica can be subjected to almost...electronics, solid-state lasers , optical propagation and communications; cw and pulsed chemical laser development, optical resonators, beam control

Crude oil desulfurization

NASA Technical Reports Server (NTRS)

Kalvinskas, J. J.; Hsu, G. C.; Ernest, J. B. (Inventor)

1982-01-01

High sulfur crude oil is desulfurized by a low temperature (25-80 C.) chlorinolysis at ambient pressure in the absence of organic solvent or diluent but in the presence of water (water/oil=0.3) followed by a water and caustic wash to remove sulfur and chlorine containing reaction products. The process described can be practiced at a well site for the recovery of desulfurized oil used to generate steam for injection into the well for enhanced oil recovery.

Helmet-mounted uncooled FPA camera for use in firefighting applications

NASA Astrophysics Data System (ADS)

Wu, Cheng; Feng, Shengrong; Li, Kai; Pan, Shunchen; Su, Junhong; Jin, Weiqi

2000-05-01

From the concept and need background of firefighters to the thermal imager, we discuss how the helmet-mounted camera applied in the bad environment of conflagration, especially at the high temperature, and how the better matching between the thermal imager with the helmet will be put into effect in weight, size, etc. Finally, give a practical helmet- mounted IR camera based on the uncooled focal plane array detector for in firefighting.

Investigating Chemistry Students' Learning about the Relationship between the Temperature and the Pressure of a Gas Using a Microcomputer-Based Laboratory (MBL): A Word of Caution.

ERIC Educational Resources Information Center

Thomas, Gregory P.; McRobbie, Campbell J.

2002-01-01

Focuses on practices related to the use of a microcomputer-based laboratory (MBL) in a high school chemistry course in which students studied gases and kinetic theory. Reports that little or no higher order thinking was employed as students engaged in using the MBL and that some alternative conceptions were still evident. (Contains 42 references.)…

Machining and grinding: High rate deformation in practice

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

Follansbee, P.S.

1993-04-01

Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of thismore » paper is to outline the current understanding of strain rate effects in metals.« less

Machining and grinding: High rate deformation in practice

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

Follansbee, P.S.

1993-01-01

Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of thismore » paper is to outline the current understanding of strain rate effects in metals.« less

Significantly enhanced critical current density in nano-MgB2 grains rapidly formed at low temperature with homogeneous carbon doping

NASA Astrophysics Data System (ADS)

Liu, Yongchang; Lan, Feng; Ma, Zongqing; Chen, Ning; Li, Huijun; Barua, Shaon; Patel, Dipak; Shahriar, M.; Hossain, Al; Acar, S.; Kim, Jung Ho; Xue Dou, Shi

2015-05-01

High performance MgB2 bulks using carbon-coated amorphous boron as a boron precursor were fabricated by Cu-activated sintering at low temperature (600 °C, below the Mg melting point). Dense nano-MgB2 grains with a high level of homogeneous carbon doping were formed in these MgB2 samples. This type of microstructure can provide a stronger flux pinning force, together with depressed volatility and oxidation of Mg owing to the low-temperature Cu-activated sintering, leading to a significant improvement of critical current density (Jc) in the as-prepared samples. In particular, the value of Jc for the carbon-coated (Mg1.1B2)Cu0.05 sample prepared here is even above 1 × 105 A cm-2 at 20 K, 2 T. The results herein suggest that the combination of low-temperature Cu-activated sintering and employment of carbon-coated amorphous boron as a precursor could be a promising technique for the industrial production of practical MgB2 bulks or wires with excellent Jc, as the carbon-coated amorphous boron powder can be produced commercially at low cost, while the addition of Cu is very convenient and inexpensive.

Single-ended retroreflection sensors for absorption spectroscopy in high-temperature environments

NASA Astrophysics Data System (ADS)

Melin, Scott T.; Wang, Ze; Neal, Nicholas J.; Rothamer, David A.; Sanders, Scott T.

2017-04-01

Novel single-ended sensor arrangements are demonstrated for in situ absorption spectroscopy in combustion and related test articles. A single-ended optical access technique based on back-reflection from a polished test article surface is presented. H2O vapor absorption spectra were measured at 10 kHz in a homogeneous-charge compression-ignition engine using a sensor of this design collecting back-reflection from a polished piston surface. The measured spectra show promise for high-repetition-rate measurements in practical combustion devices. A second sensor was demonstrated based on a modification to this optical access technique. The sensor incorporates a nickel retroreflective surface as back-reflector to reduce sensitivity to beam steering and misalignment. In a propane-fired furnace, H2O vapor absorption spectra were obtained over the range 7315-7550 cm- 1 at atmospheric pressure and temperatures up to 775 K at 20 Hz using an external-cavity diode laser spectrometer. Gas properties of temperature and mole fraction were obtained from this furnace data using a band-shape spectral fitting technique. The temperature accuracy of the band-shape fitting was demonstrated to be ±1.3 K for furnace measurements at atmospheric pressure. These results should extend the range of applications in which absorption spectroscopy sensors are attractive candidates.

Observation of fast scintillation of cryogenic PbI/sub 2/ with VLPCs

NASA Astrophysics Data System (ADS)

Moses, W. W.; Choong, W.-S.; Derenzo, S. E.; Bross, A. D.; Dysert, R.; Rykalin, V. V.; Shah, K. S.; Klugerman, M.

2004-10-01

At cryogenic temperatures (/spl sim/10 K), undoped lead iodide (PbI/sub 2/) has material and scintillation properties that are very attractive for positron emission tomography (PET). However, the PbI/sub 2/ emissions are quenched at temperatures >40 K, so close optical coupling between the scintillator and photodetector requires a photodetector that also operates at cryogenic temperatures. This suggests the visible light photon counter (VLPC), which operates at similar temperatures and combines high gain and high quantum efficiency. We proximity couple (0.001 in air gap) PbI/sub 2/ crystals with 1.0-2.5 mm dimensions to a 1 mm diameter VLPC and cool the system to 8.5 K. Signals with short (<10 ns) duration are observed. When excited with 511 keV photons, a coincidence timing resolution of 1.3 ns full-width at half-maximum is measured. While a clear photopeak is observed for 122 keV excitation, no clear photopeak is seen under 511 keV excitation (possibly due to the poor optical quality of the PbI/sub 2/ crystals). While the present configuration must be scaled-up considerably, a cryogenic PbI/sub 2//VLPC combination may eventually become the basis for a practical time-of-flight PET camera.

Simulating US Agriculture in a Modern Dust Bowl Drought

NASA Technical Reports Server (NTRS)

Glotter, Michael; Elliott, Joshua

2016-01-01

Drought-induced agricultural loss is one of the most costly impacts of extreme weather, and without mitigation, climate change is likely to increase the severity and frequency of future droughts. The Dust Bowl of the 1930s was the driest and hottest for agriculture in modern US history. Improvements in farming practices have increased productivity, but yields today are still tightly linked to climate variation and the impacts of a 1930s-type drought on current and future agricultural systems remain unclear. Simulations of biophysical process and empirical models suggest that Dust-Bowl-type droughts today would have unprecedented consequences, with yield losses approx.50% larger than the severe drought of 2012. Damages at these extremes are highly sensitive to temperature, worsening by approx.25% with each degree centigrade of warming. We find that high temperatures can be more damaging than rainfall deficit, and, without adaptation, warmer mid-century temperatures with even average precipitation could lead to maize losses equivalent to the Dust Bowl drought. Warmer temperatures alongside consecutive droughts could make up to 85% of rain-fed maize at risk of changes that may persist for decades. Understanding the interactions of weather extremes and a changing agricultural system is therefore critical to effectively respond to, and minimize, the impacts of the next extreme drought event.

A feasibility study for high-temperature titanium reduction from TiCl4 using a magnesiothermic process

NASA Astrophysics Data System (ADS)

Ivanov, S. L.; Zablotsky, D.

2018-05-01

The current industrial practice for titanium extraction is a complex procedure, which produces a porous reaction mass of sintered titanium particulates fused to a steel retort wall with magnesium and MgCl2 trapped in the interstices. The reactor temperature is limited to approx. 900 °C due to the formation of fusible TiFe eutectic, which corrodes the retort and degrades the quality of titanium sponge. Here we examine the theoretical foundations and technological possibilities to design a shielded retort of niobium-zirconium alloy NbZr(1%), which is resistant to corrosion by titanium at high temperature. We consider the reactor at a temperature of approx. 1150 °C. Supplying stoichiometric quantities of reagents enables the reaction in the gas phase, whereas the exothermic process sustains the combustion of the reaction zone. When the pathway to the condenser is open, vacuum separation and evacuation of vaporized magnesium dichloride and excess magnesium into the water-cooled condenser take place. As both the reaction and the evacuation occur within seconds, the yield of the extraction is improved. We anticipate new possibilities for designing a device combining the retort function to conduct the reduction in the gas phase with fast vacuum separation of the reaction products and distillation of magnesium dichloride.

Amidine-Functionalized Poly(2-vinyl-4,4-dimethylazlactone) for Selective and Efficient CO 2 Fixing

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

Barkakaty, Balaka; Browning, Katie L.; Sumpter, Bobby

Development of novel polymeric materials capable of efficient CO 2 capture and separation under ambient conditions is crucial for cost-effective and practical industrial applications. Here we report the facile synthesis of a new CO 2-responsive polymer through post-polymerization modification of poly(2 vinyl-4,4-dimethylazlactone) (PVDMA). The reactive pendant azlactone groups of PVDMA are easily modified with 4-(N-methyltetrahydropyrimidine) benzyl alcohol (PBA) without any by-product formation. FTIR and TGA experiments show the new PBA functionalized polymer powder can reversibly capture CO 2 at room temperature and under atmospheric pressure. CO2 capture was selective, showing a high fixing efficiency even with a mixed gas systemmore » (20% CO 2, 80% N 2) similar to flue gas. CO 2 release occurred at room temperature and release profiles were investigated as a function of temperature. Density Functional Theory (DFT) calculations coupled with modeling and simulation reveal the presence of two CO 2 binding sites in the PBA functionalized polymer resulting in a two-step CO 2 release at room temperature. Finally, we find that the ease of material preparation, high fixing efficiency, and robust release characteristics suggest that post-polymerization modification may be a useful route to designing new materials for CO 2 capture.« less

A Novel Approach Toward Fabrication of High Performance Thin Film Composite Polyamide Membranes.

PubMed

Khorshidi, Behnam; Thundat, Thomas; Fleck, Brian A; Sadrzadeh, Mohtada

2016-02-29

A practical method is reported to enhance water permeability of thin film composite (TFC) polyamide (PA) membranes by decreasing the thickness of the selective PA layer. The composite membranes were prepared by interfacial polymerization (IP) reaction between meta-phenylene diamine (MPD)-aqueous and trimesoyl chloride (TMC)-organic solvents at the surface of polyethersulfone (PES) microporous support. Several PA TFC membranes were prepared at different temperatures of the organic solution ranging from -20 °C to 50 °C. The physico-chemical and morphological properties of the synthesized membranes were carefully characterized using serval analytical techniques. The results confirmed that the TFC membranes, synthesized at sub-zero temperatures of organic solution, had thinner and smoother PA layer with a greater degree of cross-linking and wettability compared to the PA films prepared at 50 °C. We demonstrated that reducing the temperature of organic solution effectively decreased the thickness of the PA active layer and thus enhanced water permeation through the membranes. The most water permeable membrane was prepared at -20 °C and exhibited nine times higher water flux compared to the membrane synthesized at room temperature. The method proposed in this report can be effectively applied for energy- and cost-efficient development of high performance nanofiltration and reverse osmosis membranes.

FORWINE - Statistical Downscaling of Seasonal forecasts for wine

NASA Astrophysics Data System (ADS)

Cardoso, Rita M.; Soares, Pedro M. M.; Miranda, Pedro M. A.

2016-04-01

The most renowned viticulture regions in the Iberian Peninsula have a long standing tradition in winemaking and are considered world-class grapevine (Vitis Vinifera L.) producing regions. Portugal is the 11th wine producer in the world, with internationally acclaimed wines, such as Port wine, and vineyards across the whole territory. Climate is widely acknowledged of one of the most important factors for grapevine development and growth (Fraga et al. 2014a and b; Jackson et al. 1993; Keller 2010). During the growing season (April-October in the Northern Hemisphere) of this perennial and deciduous crop, the climatic conditions are responsible for numerous morphologically and physiological changes. Anomalously low February-March mean temperature, anomalously high May mean temperature and anomalously high March precipitation tend to be favourable to wine production in the Douro Valley. Seasonal forecast of precipitation and temperature tailored to fit critical thresholds, for crucial seasons, can be used to inform management practices (viz. phytosanitary measures, land operations, marketing campaigns) and develop a wine production forecast. Statistical downscaling of precipitation, maximum, minimum temperatures is used to model wine production following Santos et al. (2013) and to calculate bioclimatic indices. The skill of the ensemble forecast is evaluated through anomaly correlation, ROC area, spread-error ratio and CRPS

Amidine-Functionalized Poly(2-vinyl-4,4-dimethylazlactone) for Selective and Efficient CO 2 Fixing

DOE PAGES

Barkakaty, Balaka; Browning, Katie L.; Sumpter, Bobby; ...

2016-02-12

Development of novel polymeric materials capable of efficient CO 2 capture and separation under ambient conditions is crucial for cost-effective and practical industrial applications. Here we report the facile synthesis of a new CO 2-responsive polymer through post-polymerization modification of poly(2 vinyl-4,4-dimethylazlactone) (PVDMA). The reactive pendant azlactone groups of PVDMA are easily modified with 4-(N-methyltetrahydropyrimidine) benzyl alcohol (PBA) without any by-product formation. FTIR and TGA experiments show the new PBA functionalized polymer powder can reversibly capture CO 2 at room temperature and under atmospheric pressure. CO2 capture was selective, showing a high fixing efficiency even with a mixed gas systemmore » (20% CO 2, 80% N 2) similar to flue gas. CO 2 release occurred at room temperature and release profiles were investigated as a function of temperature. Density Functional Theory (DFT) calculations coupled with modeling and simulation reveal the presence of two CO 2 binding sites in the PBA functionalized polymer resulting in a two-step CO 2 release at room temperature. Finally, we find that the ease of material preparation, high fixing efficiency, and robust release characteristics suggest that post-polymerization modification may be a useful route to designing new materials for CO 2 capture.« less

Simulating US agriculture in a modern Dust Bowl drought.

PubMed

Glotter, Michael; Elliott, Joshua

2016-12-12

Drought-induced agricultural loss is one of the most costly impacts of extreme weather 1-3 , and without mitigation, climate change is likely to increase the severity and frequency of future droughts 4,5 . The Dust Bowl of the 1930s was the driest and hottest for agriculture in modern US history. Improvements in farming practices have increased productivity, but yields today are still tightly linked to climate variation 6 and the impacts of a 1930s-type drought on current and future agricultural systems remain unclear. Simulations of biophysical process and empirical models suggest that Dust-Bowl-type droughts today would have unprecedented consequences, with yield losses ∼50% larger than the severe drought of 2012. Damages at these extremes are highly sensitive to temperature, worsening by ∼25% with each degree centigrade of warming. We find that high temperatures can be more damaging than rainfall deficit, and, without adaptation, warmer mid-century temperatures with even average precipitation could lead to maize losses equivalent to the Dust Bowl drought. Warmer temperatures alongside consecutive droughts could make up to 85% of rain-fed maize at risk of changes that may persist for decades. Understanding the interactions of weather extremes and a changing agricultural system is therefore critical to effectively respond to, and minimize, the impacts of the next extreme drought event.

Structured inspection of medications carried and stored by emergency medical services agencies identifies practices that may lead to medication errors.

PubMed

Kupas, Douglas F; Shayhorn, Meghan A; Green, Paul; Payton, Thomas F

2012-01-01

Medications are essential to emergency medical services (EMS) agencies when providing lifesaving care, but the EMS environment has challenges related to safe medication storage when compared with a hospital setting. We developed a structured process, based on common pharmacy practices, to review medications carried by EMS agencies to identify situations that may lead to medication error and to determine some best practices that may reduce potential errors and the risk of patient harm. To provide a descriptive account of EMS practices related to carrying and storing medications that have the potential for causing a medication administration error or patient harm. Using a structured process for inspection, an emergency medicine pharmacist and emergency physician(s) reviewed the medication carrying and storage practices of all nine advanced life support ambulance agencies within a five-county EMS region. Each medication carried and stored by the EMS agency was inspected for predetermined and spontaneously observed issues that could lead to medication error. These issues were documented and photographed. Two EMS medical directors reviewed each potential error for the risk of producing patient harm and assigned each to a category of high, moderate, or low risk. Because issues of temperature on EMS medications have been addressed elsewhere, this study concentrated on potential for EMS medication administration errors exclusive of storage temperatures. When reviewing medications carried by the nine EMS agencies, 38 medication safety issues were identified (range 1 to 8 per EMS agency). Of these, 16 were considered to be high risk, 14 moderate risk, and eight low risk for patient harm. Examples of potential issues included carrying expired medications, container-labeling issues, different medications stored in look-alike vials or prefilled syringes in the same compartment, and carrying crystalloid solutions next to solutions premixed with a medication. When reviewing medications stored at the EMS agency stations, eight safety issues were identified (range from 0 to 4 per station), including five moderate-risk and three low-risk issues. No agency had any high-risk medication issues related to storage of medication stock in the station. We observed potential medication safety issues related to how medications are carried and stored at all nine EMS agencies in a five-county region. Understanding these issues may assist EMS agencies in reducing the potential for a medication error and risk of patient harm. More research is needed to determine whether following these suggested best practices for carrying medications on EMS vehicles actually reduces errors in medication administration by EMS providers or decreases patient harm.

Increasing the operation temperature of polymer electrolyte membranes for fuel cells: From nanocomposites to hybrids

NASA Astrophysics Data System (ADS)

Licoccia, Silvia; Traversa, Enrico

Among the possible systems investigated for energy production with low environmental impact, polymeric electrolyte membrane fuel cells (PEMFCs) are very promising as electrochemical power sources for application in portable technology and electric vehicles. For practical applications, operating FCs at temperatures above 100 °C is desired, both for hydrogen and methanol fuelled cells. When hydrogen is used as fuel, an increase of the cell temperature produces enhanced CO tolerance, faster reaction kinetics, easier water management and reduced heat exchanger requirement. The use of methanol instead of hydrogen as a fuel for vehicles has several practical benefits such as easy transport and storage, but the slow oxidation kinetics of methanol needs operating direct methanol fuel cells (DMFCs) at intermediate temperatures. For this reason, new membranes are required. Our strategy to achieve the goal of operating at temperatures above 120 °C is to develop organic/inorganic hybrid membranes. The first approach was the use of nanocomposite class I hybrids where nanocrystalline ceramic oxides were added to Nafion. Nanocomposite membranes showed enhanced characteristics, hence allowing their operation up to 130 °C when the cell was fuelled with hydrogen and up to 145 °C in DMFCs, reaching power densities of 350 mW cm -2. The second approach was to prepare Class II hybrids via the formation of covalent bonds between totally aromatic polymers and inorganic clusters. The properties of such covalent hybrids can be modulated by modifying the ratio between organic and inorganic groups and the nature of the chemical components allowing to reach high and stable conductivity values up to 6.4 × 10 -2 S cm -1 at 120 °C.

A comparison of technologies used for estimation of body temperature.

PubMed

Mangat, Jasdip; Standley, Thomas; Prevost, Andrew; Vasconcelos, Joana; White, Paul

2010-09-01

Body temperature measurement is an important clinical parameter. The performance of a number of non-invasive thermometers was measured by comparing intra- and inter-operator variability (n = 100) and clinical accuracy (n = 61). Variability was elevated in febrile compared to normothermic subjects for axillary and oral electronic contact thermometer measures and a temporal artery thermometer (p < 0.001 for both). Temporal artery thermometry and one mode of an infrared tympanic thermometer demonstrated significant clinical inaccuracy (p < 0.001 for both). Electronic contact thermometer repeatability and reproducibility are highly variable in febrile adults both in the axilla and oral cavity. Infrared thermometry of the skin over the superficial temporal artery is unreliable for measuring core body temperature, particularly in febrile subjects and patients in theatre. The infrared tympanic thermometers tested are acceptable for clinical practice; however, care should be exercised with the different modes of operation offered.

Summary of the research and development effort on the supercritical CO2 cycle

NASA Astrophysics Data System (ADS)

Fraas, A. P.

1981-06-01

The supercritical CO2 cycle has the advantage over a conventional closed cycle gas turbine in that the compression work phase of the cycle can be carried out close to the critical point and hence aerodynamic losses in the compressor are reduced and the cycle efficiency increased for a given turbine inlet temperature. However, the practicable turbine inlet temperature is reduced by permissible stresses in the heater tubes because the peak pressure in the cycle must be approx. 260 atm in order to have the compression process take place close to the critical point of the working fluid. The high system pressure also makes the capital cost of the heat exchangers and gas piping higher than that for a conventional closed cycle gas turbine. Further, the waste heat from the cycle must be rejected at too low a temperature for it to be useful for industrial process heat or for district heating systems.

Acoustic thermometry for detecting quenches in superconducting coils and conductor stacks

NASA Astrophysics Data System (ADS)

Marchevsky, M.; Gourlay, S. A.

2017-01-01

Quench detection capability is essential for reliable operation and protection of superconducting magnets, coils, cables, and machinery. We propose a quench detection technique based on sensing local temperature variations in the bulk of a superconducting winding by monitoring its transient acoustic response. Our approach is primarily aimed at coils and devices built with high-temperature superconductor materials where quench detection using standard voltage-based techniques may be inefficient due to the slow velocity of quench propagation. The acoustic sensing technique is non-invasive, fast, and capable of detecting temperature variations of less than 1 K in the interior of the superconductor cable stack in a 77 K cryogenic environment. We show results of finite element modeling and experiments conducted on a model superconductor stack demonstrating viability of the technique for practical quench detection, discuss sensitivity limits of the technique, and its various applications.

Microstructure of Turbulence in the Stably Stratified Boundary Layer

NASA Astrophysics Data System (ADS)

Sorbjan, Zbigniew; Balsley, Ben B.

2008-11-01

The microstructure of a stably stratified boundary layer, with a significant low-level nocturnal jet, is investigated based on observations from the CASES-99 campaign in Kansas, U.S.A. The reported, high-resolution vertical profiles of the temperature, wind speed, wind direction, pressure, and the turbulent dissipation rate, were collected under nocturnal conditions on October 14, 1999, using the CIRES Tethered Lifting System. Two methods for evaluating instantaneous (1-sec) background profiles are applied to the raw data. The background potential temperature is calculated using the “bubble sort” algorithm to produce a monotonically increasing potential temperature with increasing height. Other scalar quantities are smoothed using a running vertical average. The behaviour of background flow, buoyant overturns, turbulent fluctuations, and their respective histograms are presented. Ratios of the considered length scales and the Ozmidov scale are nearly constant with height, a fact that can be applied in practice for estimating instantaneous profiles of the dissipation rate.

The effects of solar radiation and black body re-radiation on thermal comfort.

PubMed

Hodder, Simon; Parsons, Ken

2008-04-01

When the sun shines on people in enclosed spaces, such as in buildings or vehicles, it directly affects thermal comfort. There is also an indirect effect as surrounding surfaces are heated exposing a person to re-radiation. This laboratory study investigated the effects of long wave re-radiation on thermal comfort, individually and when combined with direct solar radiation. Nine male participants (26.0 +/- 4.7 years) took part in three experimental sessions where they were exposed to radiation from a hot black panel heated to 100 degrees C; direct simulated solar radiation of 600 Wm(-2) and the combined simulated solar radiation and black panel radiation. Exposures were for 30 min, during which subjective responses and mean skin temperatures were recorded. The results showed that, at a surface temperature of 100 degrees C (close to maximum in practice), radiation from the flat black panel provided thermal discomfort but that this was relatively small when compared with the effects of direct solar radiation. It was concluded that re-radiation, from a dashboard in a vehicle, for example, will not have a major direct influence on thermal comfort and that existing models of thermal comfort do not require a specific modification. These results showed that, for the conditions investigated, the addition of re-radiation from internal components has an effect on thermal sensation when combined with direct solar radiation. However, it is not considered that it will be a major factor in a real world situation. This is because, in practice, dashboards are unlikely to maintain very high surface temperatures in vehicles without an unacceptably high air temperature. This study quantifies the contribution of short- and long-wave radiation to thermal comfort. The results will aid vehicle designers to have a better understanding of the complex radiation environment. These include direct radiation from the sun as well as re-radiation from the dashboard and other internal surfaces.

A Smartphone-Based Driver Safety Monitoring System Using Data Fusion

PubMed Central

Lee, Boon-Giin; Chung, Wan-Young

2012-01-01

This paper proposes a method for monitoring driver safety levels using a data fusion approach based on several discrete data types: eye features, bio-signal variation, in-vehicle temperature, and vehicle speed. The driver safety monitoring system was developed in practice in the form of an application for an Android-based smartphone device, where measuring safety-related data requires no extra monetary expenditure or equipment. Moreover, the system provides high resolution and flexibility. The safety monitoring process involves the fusion of attributes gathered from different sensors, including video, electrocardiography, photoplethysmography, temperature, and a three-axis accelerometer, that are assigned as input variables to an inference analysis framework. A Fuzzy Bayesian framework is designed to indicate the driver’s capability level and is updated continuously in real-time. The sensory data are transmitted via Bluetooth communication to the smartphone device. A fake incoming call warning service alerts the driver if his or her safety level is suspiciously compromised. Realistic testing of the system demonstrates the practical benefits of multiple features and their fusion in providing a more authentic and effective driver safety monitoring. PMID:23247416

Resistance of a northwestern crayfish, Pacifastacus leniusculus (Dana), to elevated temperatures

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

Becker, C.D.; Genoway, R.G.; Merrill, J.A.

1975-04-01

Pacifastacus leniusculus from two populations in Washington State, the central Columbia River and a small tributary, were acclimated at 5/sup 0/C intervals and exposed to elevated temperatures in 48 hour thermal bioassays. The upper lethal temperature for both crayfish populations increased relatively slightly, from about 28.5 to 31.5/sup 0/C, over the entire acclimation range. A rise of 1/sup 0/C in test temperature often represented the difference between zero and total mortality when lethal limits were approached. The ultimate upper lethal temperature was near 32 to 33/sup 0/C. Statistically significant differences in thermal resistance patterns (slope and spacing of regression lines)more » occurred between the two crayfish populations at all acclimation levels, but resistance in terms of eventual mortality was similar for practical purposes. Moulting individuals were particularly susceptible to high temperature stress. Mature, pre-breeding female crayfish from the Columbia River during fall appeared less resistant, and egg-bearing females during winter more resistant, than other individuals. Larger crayfish from the Columbia River were slightly less resistant to elevated temperatures than smaller ones, and females were more resistant than males. The upper temperature triangle for P. leniusculus encompasses an area of 424/sup 0/C/sup 2/. This freshwater decapod is more tolerant of elevated temperatures than native salmonids, but less tolerant than some introduced ''warmwater'' fish.« less

Integration of a molten carbonate fuel cell with a direct exhaust absorption chiller

NASA Astrophysics Data System (ADS)

Margalef, Pere; Samuelsen, Scott

A high market value exists for an integrated high-temperature fuel cell-absorption chiller product throughout the world. While high-temperature, molten carbonate fuel cells are being commercially deployed with combined heat and power (CHP) and absorption chillers are being commercially deployed with heat engines, the energy efficiency and environmental attributes of an integrated high-temperature fuel cell-absorption chiller product are singularly attractive for the emerging distributed generation (DG) combined cooling, heating, and power (CCHP) market. This study addresses the potential of cooling production by recovering and porting the thermal energy from the exhaust gas of a high-temperature fuel cell (HTFC) to a thermally activated absorption chiller. To assess the practical opportunity of serving an early DG-CCHP market, a commercially available direct fired double-effect absorption chiller is selected that closely matches the exhaust flow and temperature of a commercially available HTFC. Both components are individually modeled, and the models are then coupled to evaluate the potential of a DG-CCHP system. Simulation results show that a commercial molten carbonate fuel cell generating 300 kW of electricity can be effectively coupled with a commercial 40 refrigeration ton (RT) absorption chiller. While the match between the two "off the shelf" units is close and the simulation results are encouraging, the match is not ideal. In particular, the fuel cell exhaust gas temperature is higher than the inlet temperature specified for the chiller and the exhaust flow rate is not sufficient to achieve the potential heat recovery within the chiller heat exchanger. To address these challenges, the study evaluates two strategies: (1) blending the fuel cell exhaust gas with ambient air, and (2) mixing the fuel cell exhaust gases with a fraction of the chiller exhaust gas. Both cases are shown to be viable and result in a temperature drop and flow rate increase of the gases before the chiller inlet. The results show that no risk of cold end corrosion within the chiller heat exchanger exists. In addition, crystallization is not an issue during system operation. Accounting for the electricity and the cooling produced and disregarding the remaining thermal energy, the second strategy is preferred and yields an overall estimated efficiency of 71.7%.

Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO2 Nanosheets With Exposed (001) Facets.

PubMed

Shi, Ting; Duan, Youyu; Lv, Kangle; Hu, Zhao; Li, Qin; Li, Mei; Li, Xiaofang

2018-01-01

Anatase TiO 2 (A-TiO 2 ) usually exhibits superior photocatalytic activity than rutile TiO 2 (R-TiO 2 ). However, the phase transformation from A-TiO 2 to R-TiO 2 will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO 2 photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO 2 nanosheets (TiO 2 -NSs) with super thermal stability was prepared by calcination of TiOF 2 cubes. With increase in the calcination temperature from 300 to 600°C, TiOF 2 transforms into TiO 2 hollow nanoboxes (TiO 2 -HNBs) assembly from TiO 2 -NSs via Ostwald Rippening process. Almost all of the TiO 2 -HNBs are disassembled into discrete TiO 2 -NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO 2 to R-TiO 2 begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO 2 -NSs transforms into R-TiO 2 . The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO 2 -NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO 2 -NSs which are prepared by calcination of TiOF 2 cubes.

Ceramic applications in the advanced Stirling automotive engine

NASA Technical Reports Server (NTRS)

Tomazic, W. A.; Cairelli, J. E.

1977-01-01

The ideal cycle, its application to a practical machine, and the specific advantages of high efficiency, low emissions, multi-fuel capability, and low noise of the stirling engine are discussed. Certain portions of the Stirling engine must operate continuously at high temperature. Ceramics offer the potential of cost reduction and efficiency improvement for advanced engine applications. Potential applications for ceramics in Stirling engines, and some of the special problems pertinent to using ceramics in the Stirling engine are described. The research and technology program in ceramics which is planned to support the development of advanced Stirling engines is outlined.

A review of nosocomial Salmonella outbreaks: infection control interventions found effective.

PubMed

Lee, M B; Greig, J D

2013-03-01

To review nosocomial salmonellosis outbreaks to identify: mode of transmission; morbidity and mortality patterns; and recommendations for control and prevention. Documented nosocomial salmonellosis outbreaks in hospitals published from January 1995 to November 2011, written in the English language, were systematically reviewed. The study methodology incorporated steps from the PRISMA statement for a high quality review process. Computer-aided searches of Scopus, CAB Global Health and CINAHL(®), the Cumulative Index to Nursing and Allied Health Literature were completed to identify relevant outbreak reports written in English. To validate the electronic search methodology, bibliographies and reference lists of relevant review articles were hand-searched. Public health and government websites were searched for nosocomial salmonellosis. Fifty-two relevant reports were identified. The most frequently reported routes of transmission were food 31/52 (59.6%) and person-to-person transmission 7/52 (13.5%). Actions taken during the outbreak to control transmission included improvements to: 1) infection control practices (41.8% of actions); isolation or cohorting patients, hand hygiene practices, and enhancing cleaning and disinfection in patient care areas; and 2) food handling practices (24.4% of actions); reviewing food preparation practices, enhancing cleaning and sanitation of the kitchen, and controlling food temperatures. Investigators made recommendations retrospectively in outbreak reports to provide direction to health centees but these recommendations were not statistically evaluated for effectiveness. More emphasis should be placed on improving food handling practices, such as training food workers, monitoring food temperatures, and not using raw foods of animal origin, to prevent nosocomial salmonellosis outbreaks in hospitals because almost 60% of the outbreaks were foodborne. Copyright © 2013 The Royal Institute of Public Health. All rights reserved.

Evaluation of vaccine cold chain in urban health centers of municipal corporation of surat city, Western India.

PubMed

Naik, Ashish K; Rupani, Mihir P; Bansal, R K

2013-12-01

The success of immunization depends highly on the level of cold chain maintenance. The aim of the study was to assess the condition of cold chain equipment, practices adopted for cold chain maintenance and knowledge of the vaccinators. It was a cross-sectional study conducted in 20 UHCs of Surat Municipal Corporation (SMC). Cold chain equipment were observed with regards to their condition, along with the practices adopted by vaccinators for cold chain maintenance. A pre-designed and pre-tested questionnaire was used to interview the vaccinators regarding their knowledge and awareness regarding cold chain practices, management and handling. Data were entered and analyzed using Epi Info v 3.5.1. Simple proportions were calculated. Absence of separate stabilizer for deep freezers and ILRs (85%), ill-maintained temperature-record register, lack of criss-cross pattern of ice packs in deep freezer (65%), presence of things other than ice packs in deep freezer (10%) and things other than vaccines in ILR (10%) indicate poor cold chain maintenance. In addition to this, expired vaccines in ILR (5%), vaccines in the "unusable" stages of VVM (15%), lack of emergency contact number nearby in case of cold chain failure (85%), lack of inverter (85%), lack of generator (85%) and failure to note time of reconstitution on the vaccine vial at the time of vaccination (25%) indicate poor cold chain practices. Lack of knowledge of defrosting of ILR and deep freezer (45%), lack of knowledge about Shake test (40%), lack of knowledge of temperature range to be maintained in deep freezer (70%) and in ILR (15%) indicate poor knowledge of vaccinators. Cold chain maintenance and practices need improvement. Knowledge of vaccinators was overall unsatisfactory.

Practical high temperature (80 °C) storage study of industrially manufactured Li-ion batteries with varying electrolytes

NASA Astrophysics Data System (ADS)

Genieser, R.; Loveridge, M.; Bhagat, R.

2018-05-01

A previous study is focused on high temperature cycling of industrially manufactured Li-ion pouch cells (NMC-111/Graphite) with different electrolytes at 80 °C [JPS 373 (2018) 172-183]. Within this article the same test set-up is used, with cells stored for 30 days at different open circuit potentials and various electrolytes instead of electrochemical cycling. The most pronounced cell degradation (capacity fade and resistance increase) happens at high potentials. However appropriate electrolyte formulations are able to suppress ageing conditions by forming passivating surface films on both electrodes. Compared with electrochemical cycling at 80 °C, cells with enhanced electrolytes only show a slight resistance increase during storage and the capacity fade is much lower. Additionally it is shown for the first time, that the resistance is decreasing and capacity is regained once these cells are cycled again at room temperature. This is not the case for electrolytes without additives or just vinylene carbonate (VC) as an additive. It is further shown that the resistance increase of cells with the other electrolytes is accompanied by a reduction of the cell volume during further cycling. This behaviour is likely related to the reduction of CO2 at the anode to form additional SEI layer components.

Molecular Functionalization of Graphene Oxide for Next-Generation Wearable Electronics.

PubMed

Zarrin, Hadis; Sy, Serubbabel; Fu, Jing; Jiang, Gaopeng; Kang, Keunwoo; Jun, Yun-Seok; Yu, Aiping; Fowler, Michael; Chen, Zhongwei

2016-09-28

Acquiring reliable and efficient wearable electronics requires the development of flexible electrolyte membranes (EMs) for energy storage systems with high performance and minimum dependency on the operating conditions. Herein, a freestanding graphene oxide (GO) EM is functionalized with 1-hexyl-3-methylimidazolium chloride (HMIM) molecules via both covalent and noncovalent bonds induced by esterification reactions and electrostatic πcation-π stacking, respectively. Compared to the commercial polymeric membrane, the thin HMIM/GO membrane demonstrates not only slightest performance sensitivity to the operating conditions but also a superior hydroxide conductivity of 0.064 ± 0.0021 S cm(-1) at 30% RH and room temperature, which was 3.8 times higher than that of the commercial membrane at the same conditions. To study the practical application of the HMIM/GO membranes in wearable electronics, a fully solid-state, thin, flexible zinc-air battery and supercapacitor are made exhibiting high battery performance and capacitance at low humidified and room temperature environment, respectively, favored by the bonded HMIM molecules on the surface of GO nanosheets. The results of this study disclose the strong potential of manipulating the chemical structure of GO to work as a lightweight membrane in wearable energy storage devices, possessing highly stable performance at different operating conditions, especially at low relative humidity and room temperature.

Feasibility of Electrochemical Deposition of Nickel/Silicon Carbide Fibers Composites over Nickel Superalloys

NASA Astrophysics Data System (ADS)

Ambrosio, E. P.; Abdul Karim, M. R.; Pavese, M.; Biamino, S.; Badini, C.; Fino, P.

2017-05-01

Nickel superalloys are typical materials used for the hot parts of engines in aircraft and space vehicles. They are very important in this field as they offer high-temperature mechanical strength together with a good resistance to oxidation and corrosion. Due to high-temperature buckling phenomena, reinforcement of the nickel superalloy might be needed to increase stiffness. For this reason, it was thought to investigate the possibility of producing composite materials that might improve properties of the metal at high temperature. The composite material was produced by using electrochemical deposition method in which a composite with nickel matrix and long silicon carbide fibers was deposited over the nickel superalloy. The substrate was Inconel 718, and monofilament continuous silicon carbide fibers were chosen as reinforcement. Chemical compatibility was studied between Inconel 718 and the reinforcing fibers, with fibers both in an uncoated condition, and coated with carbon or carbon/titanium diboride. Both theoretical calculations and experiments were conducted, which suggested the use of a carbon coating over the fibers and a buffer layer of nickel to avoid unwanted reactions between the substrate and silicon carbide. Deposition was then performed, and this demonstrated the practical feasibility of the process. Yield strength was measured to detect the onset of interface debonding between the substrate and the composite layer.

Advances in catalysts for internal reforming in high temperature fuel cells

NASA Astrophysics Data System (ADS)

Dicks, A. L.

Catalytic steam reforming of natural gas is an attractive method of producing the hydrogen required by the present generation of fuel cells. The molten carbonate (MCFC) and solid oxide (SOFC) fuel cells operate at high enough temperatures for the endothermic steam reforming reaction to be carried out within the stack. For the MCFC, the conventional anodes have insufficient activity to catalyse the steam reforming of natural gas. For these cells, internal reforming can be achieved only with the addition of a separate catalyst, preferably located in close proximity to the anode. However, in the so-called `Direct Internal Reforming' configuration, attack from alkali in the MCFC may severely limit catalyst lifetime. In the case of the state-of-the-art SOFC, natural gas can be reformed directly on the nickel cermet anode. However, in the SOFC, temperature variations in the cell caused by the reforming reaction may limit the amount of internal reforming that can be allowed in practice. In addition, some external pre-reforming may be desirable to remove high molecular weight hydrocarbons from the fuel gas, which would otherwise crack to produce elemental carbon. Degradation of the SOFC anode may also be a problem when internal reforming is carried out. This has prompted several research groups to investigate the use of alternative anode materials.

Microfluidic and nanofluidic phase behaviour characterization for industrial CO2, oil and gas.

PubMed

Bao, Bo; Riordon, Jason; Mostowfi, Farshid; Sinton, David

2017-08-08

Microfluidic systems that leverage unique micro-scale phenomena have been developed to provide rapid, accurate and robust analysis, predominantly for biomedical applications. These attributes, in addition to the ability to access high temperatures and pressures, have motivated recent expanded applications in phase measurements relevant to industrial CO 2 , oil and gas applications. We here present a comprehensive review of this exciting new field, separating microfluidic and nanofluidic approaches. Microfluidics is practical, and provides similar phase properties analysis to established bulk methods with advantages in speed, control and sample size. Nanofluidic phase behaviour can deviate from bulk measurements, which is of particular relevance to emerging unconventional oil and gas production from nanoporous shale. In short, microfluidics offers a practical, compelling replacement of current bulk phase measurement systems, whereas nanofluidics is not practical, but uniquely provides insight into phase change phenomena at nanoscales. Challenges, trends and opportunities for phase measurements at both scales are highlighted.

A gold nanocluster-based fluorescent probe for simultaneous pH and temperature sensing and its application to cellular imaging and logic gates.

PubMed

Wu, Yun-Tse; Shanmugam, Chandirasekar; Tseng, Wei-Bin; Hiseh, Ming-Mu; Tseng, Wei-Lung

2016-06-07

Metal nanocluster-based nanomaterials for the simultaneous determination of temperature and pH variations in micro-environments are still a challenge. In this study, we develop a dual-emission fluorescent probe consisting of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and fluorescein-5-isothiocyanate (FITC) as temperature- and pH-responsive fluorescence signals. Under single wavelength excitation the FITC/BSA-AuNCs exhibited well-separated dual emission bands at 525 and 670 nm. When FITC was used as a reference fluorophore, FITC/BSA-AuNCs showed a good linear response over the temperature range 1-71 °C and offered temperature-independent spectral shifts, temperature accuracy, activation energy, and reusability. The possible mechanism for high temperature-induced fluorescence quenching of FITC/BSA-AuNCs could be attributed to a weakening of the Au-S bond, thereby lowering the charge transfer from BSA to AuNCs. Additionally, the pH- and temperature-responsive properties of FITC/BSA-AuNCs allow simultaneous temperature sensing from 21 to 41 °C (at intervals of 5 °C) and pH from 6.0 to 8.0 (at intervals of 0.5 pH unit), facilitating the construction of two-input AND logic gates. Three-input AND logic gates were also designed using temperature, pH, and trypsin as inputs. The practicality of using FITC/BSA-AuNCs to determine the temperature and pH changes in HeLa cells is also validated.

Extreme creep resistance in a microstructurally stable nanocrystalline alloy

NASA Astrophysics Data System (ADS)

Darling, K. A.; Rajagopalan, M.; Komarasamy, M.; Bhatia, M. A.; Hornbuckle, B. C.; Mishra, R. S.; Solanki, K. N.

2016-09-01

Nanocrystalline metals, with a mean grain size of less than 100 nanometres, have greater room-temperature strength than their coarse-grained equivalents, in part owing to a large reduction in grain size. However, this high strength generally comes with substantial losses in other mechanical properties, such as creep resistance, which limits their practical utility; for example, creep rates in nanocrystalline copper are about four orders of magnitude higher than those in typical coarse-grained copper. The degradation of creep resistance in nanocrystalline materials is in part due to an increase in the volume fraction of grain boundaries, which lack long-range crystalline order and lead to processes such as diffusional creep, sliding and rotation. Here we show that nanocrystalline copper-tantalum alloys possess an unprecedented combination of properties: high strength combined with extremely high-temperature creep resistance, while maintaining mechanical and thermal stability. Precursory work on this family of immiscible alloys has previously highlighted their thermo-mechanical stability and strength, which has motivated their study under more extreme conditions, such as creep. We find a steady-state creep rate of less than 10-6 per second—six to eight orders of magnitude lower than most nanocrystalline metals—at various temperatures between 0.5 and 0.64 times the melting temperature of the matrix (1,356 kelvin) under an applied stress ranging from 0.85 per cent to 1.2 per cent of the shear modulus. The unusual combination of properties in our nanocrystalline alloy is achieved via a processing route that creates distinct nanoclusters of atoms that pin grain boundaries within the alloy. This pinning improves the kinetic stability of the grains by increasing the energy barrier for grain-boundary sliding and rotation and by inhibiting grain coarsening, under extremely long-term creep conditions. Our processing approach should enable the development of microstructurally stable structural alloys with high strength and creep resistance for various high-temperature applications, including in the aerospace, naval, civilian infrastructure and energy sectors.

The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines for Cardiopulmonary Bypass--Temperature Management During Cardiopulmonary Bypass.

PubMed

Engelman, Richard; Baker, Robert A; Likosky, Donald S; Grigore, Alina; Dickinson, Timothy A; Shore-Lesserson, Linda; Hammon, John W

2015-08-01

In order to improve our understanding of the evidence-based literature supporting temperature management during adult cardiopulmonary bypass, The Society of Thoracic Surgeons, the Society of Cardiovascular Anesthesiology and the American Society of ExtraCorporeal Technology tasked the authors to conduct a review of the peer-reviewed literature, including: 1) optimal site for temperature monitoring, 2) avoidance of hyperthermia, 3) peak cooling temperature gradient and cooling rate, and 4) peak warming temperature gradient and rewarming rate. Authors adopted the American College of Cardiology/American Heart Association method for development clinical practice guidelines, and arrived at the following recommendations: No Recommendation No recommendation for a guideline is provided concerning optimal temperature for weaning from CPB due to insufficient published evidence. Copyright © 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Biothermal Model of Patient for Brain Hypothermia Treatment

NASA Astrophysics Data System (ADS)

Wakamatsu, Hidetoshi; Gaohua, Lu

A biothermal model of patient is proposed and verified for the brain hypothermia treatment, since the conventionally applied biothermal models are inappropriate for their unprecedented application. The model is constructed on the basis of the clinical practice of the pertinent therapy and characterized by the mathematical relation with variable ambient temperatures, in consideration of the clinical treatments such as the vital cardiopulmonary regulation. It has geometrically clear representation of multi-segmental core-shell structure, database of physiological and physical parameters with a systemic state equation setting the initial temperature of each compartment. Its step response gives the time constant about 3 hours in agreement with clinical knowledge. As for the essential property of the model, the dynamic temperature of its face-core compartment is realized, which corresponds to the tympanic membrane temperature measured under the practical anesthesia. From the various simulations consistent with the phenomena of clinical practice, it is concluded that the proposed model is appropriate for the theoretical analysis and clinical application to the brain hypothermia treatment.

Anchoring and Upgrading Ultrafine NiPd on Room-Temperature-Synthesized Bifunctional NH2 -N-rGO toward Low-Cost and Highly Efficient Catalysts for Selective Formic Acid Dehydrogenation.

PubMed

Yan, Jun-Min; Li, Si-Jia; Yi, Sha-Sha; Wulan, Ba-Ri; Zheng, Wei-Tao; Jiang, Qing

2018-03-01

Hydrogen is widely considered to be a sustainable and clean energy alternative to the use of fossil fuels in the future. Its high hydrogen content, nontoxicity, and liquid state at room temperature make formic acid a promising hydrogen carrier. Designing highly efficient and low-cost heterogeneous catalysts is a major challenge for realizing the practical application of formic acid in the fuel-cell-based hydrogen economy. Herein, a simple but effective and rapid strategy is proposed, which demonstrates the synthesis of NiPd bimetallic ultrafine particles (UPs) supported on NH 2 -functionalized and N-doped reduced graphene oxide (NH 2 -N-rGO) at room temperature. The introduction of the NH 2 N group to rGO is the key reason for the formation of the ultrafine and well-dispersed Ni 0.4 Pd 0.6 UPs (1.8 nm) with relatively large surface area and more active sites. Surprisingly, the as-prepared low-cost NiPd/NH 2 -N-rGO dsiplays excellent hydrophilicity, 100% H 2 selectivity, 100% conversion, and remarkable catalytic activity (up to 954.3 mol H 2 (mol catalyst) -1 h -1 ) for FA decomposition at room temperature even with no additive, which is much higher than that of the best catalysts so far reported. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A practical approach for predicting retention time shifts due to pressure and temperature gradients in ultra-high-pressure liquid chromatography.

PubMed

Åsberg, Dennis; Chutkowski, Marcin; Leśko, Marek; Samuelsson, Jörgen; Kaczmarski, Krzysztof; Fornstedt, Torgny

2017-01-06

Large pressure gradients are generated in ultra-high-pressure liquid chromatography (UHPLC) using sub-2μm particles causing significant temperature gradients over the column due to viscous heating. These pressure and temperature gradients affect retention and ultimately result in important selectivity shifts. In this study, we developed an approach for predicting the retention time shifts due to these gradients. The approach is presented as a step-by-step procedure and it is based on empirical linear relationships describing how retention varies as a function of temperature and pressure and how the average column temperature increases with the flow rate. It requires only four experiments on standard equipment, is based on straightforward calculations, and is therefore easy to use in method development. The approach was rigorously validated against experimental data obtained with a quality control method for the active pharmaceutical ingredient omeprazole. The accuracy of retention time predictions was very good with relative errors always less than 1% and in many cases around 0.5% (n=32). Selectivity shifts observed between omeprazole and the related impurities when changing the flow rate could also be accurately predicted resulting in good estimates of the resolution between critical peak pairs. The approximations which the presented approach are based on were all justified. The retention factor as a function of pressure and temperature was studied in an experimental design while the temperature distribution in the column was obtained by solving the fundamental heat and mass balance equations for the different experimental conditions. We strongly believe that this approach is sufficiently accurate and experimentally feasible for this separation to be a valuable tool when developing a UHPLC method. After further validation with other separation systems, it could become a useful approach in UHPLC method development, especially in the pharmaceutical industry where demands are high for robustness and regulatory oversight. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermal comfort indices of female Murrah buffaloes reared in the Eastern Amazon

NASA Astrophysics Data System (ADS)

da Silva, Jamile Andréa Rodrigues; de Araújo, Airton Alencar; Lourenço Júnior, José de Brito; dos Santos, Núbia de Fátima Alves; Garcia, Alexandre Rossetto; de Oliveira, Raimundo Parente

2015-09-01

The study aimed to develop new and more specific thermal comfort indices for buffaloes reared in the Amazon region. Twenty female Murrah buffaloes were studied for a year. The animals were fed in pasture with drinking water and mineral supplementation ad libitum. The following parameters were measured twice a week in the morning (7 AM) and afternoon (1 PM): air temperature (AT), relative air humidity (RH), dew point temperature (DPT), wet bulb temperature (WBT), black globe temperature (BGT), rectal temperature (RT), respiratory rate (RR), and body surface temperature (BST). The temperature and humidity index (THI), globe temperature and humidity index (GTHI), Benezra's comfort index (BTCI), and Ibéria's heat tolerance index (IHTI) were calculated so they could be compared to the new indices. Multivariate regression analyses were carried out using the canonical correlation model, and all indices were correlated with the physiological and climatic variables. Three pairs of indices (general, effective, and practical) were determined comprising the buffalo comfort climatic condition index (BCCCI) and the buffalo environmental comfort index (BECI). The indices were validated and a great agreement was found among the BCCCIs (general, effective, and practical), with 98.3 % between general and effective a.nd 92.6 % between general and practical. A significant correlation ( P < 0.01) was found between the new indices and the physiological and climatic variables, which indicated that these may be used in pairs to diagnose thermal stress in buffaloes reared in the Amazon.

Thermal comfort indices of female Murrah buffaloes reared in the Eastern Amazon.

PubMed

da Silva, Jamile Andréa Rodrigues; de Araújo, Airton Alencar; Lourenço Júnior, José de Brito; dos Santos, Núbia de Fátima Alves; Garcia, Alexandre Rossetto; de Oliveira, Raimundo Parente

2015-09-01

The study aimed to develop new and more specific thermal comfort indices for buffaloes reared in the Amazon region. Twenty female Murrah buffaloes were studied for a year. The animals were fed in pasture with drinking water and mineral supplementation ad libitum. The following parameters were measured twice a week in the morning (7 AM) and afternoon (1 PM): air temperature (AT), relative air humidity (RH), dew point temperature (DPT), wet bulb temperature (WBT), black globe temperature (BGT), rectal temperature (RT), respiratory rate (RR), and body surface temperature (BST). The temperature and humidity index (THI), globe temperature and humidity index (GTHI), Benezra's comfort index (BTCI), and Ibéria's heat tolerance index (IHTI) were calculated so they could be compared to the new indices. Multivariate regression analyses were carried out using the canonical correlation model, and all indices were correlated with the physiological and climatic variables. Three pairs of indices (general, effective, and practical) were determined comprising the buffalo comfort climatic condition index (BCCCI) and the buffalo environmental comfort index (BECI). The indices were validated and a great agreement was found among the BCCCIs (general, effective, and practical), with 98.3 % between general and effective a.nd 92.6 % between general and practical. A significant correlation (P < 0.01) was found between the new indices and the physiological and climatic variables, which indicated that these may be used in pairs to diagnose thermal stress in buffaloes reared in the Amazon.

Application of displacement monitoring system on high temperature steam pipe

NASA Astrophysics Data System (ADS)

Ghaffar, M. H. A.; Husin, S.; Baek, J. E.

2017-10-01

High-energy piping systems of power plants such as Main Steam (MS) pipe or Hot Reheat (HR) pipe are operating at high temperature and high pressure at base and cyclic loads. In the event of transient condition, a pipe can be deflected dramatically and caused high stress in the pipe, yielding to failure of the piping system. Periodic monitoring and walk down can identify abnormalities but limitations exist in the standard walk down practice. This paper provides a study of pipe displacement monitoring on MS pipe of coal-fired power plant to continuously capture the pipe movement behaviour at different load using 3-Dimensional Displacement Measuring System (3DDMS). The displacement trending at Location 5 and 6 (north and south) demonstrated pipes displace less than 25% to that of design movement. It was determined from synchronisation analysis that Location 7 (north) and Location 8 (south) pipe actual movement difference has exceeded the design movement difference. Visual survey at specified locations with significant displacement trending reveals issues of hydraulic snubber and piping interferences. The study demonstrated that the displacement monitoring is able to capture pipe movement at all time and allows engineer to monitor pipe movement behaviour, aids in identifying issue early for remedy action.