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Sample records for rapid thermal chemical

  1. A predictive model for the chemical vapor deposition of polysilicon in a cold wall, rapid thermal system

    SciTech Connect

    Toprac, A.J.; Trachtenberg, I.; Edgar, T.F. . Dept. of Chemical Engineering)

    1994-06-01

    The chemical vapor deposition of polysilicon from thermally activated silane in a cold wall, single-wafer rapid thermal system was studied by experimentation at a variety of low pressure conditions, including very high temperatures. The effect of diluent gas on polysilicon deposition rates was examined using hydrogen, helium, and krypton. A mass-transfer model for the chemical vapor deposition of polysilicon in a cold wall, rapid thermal system was developed. This model was used to produce an empirical rate expression for silicon deposition from silane by regressing kinetic parameters to fit experimental data. The resulting model provided accurate predictions over widely varying conditions in the experimental data.

  2. Materials characterization of rapid thermal chemical vapor deposition of titanium disilicide

    NASA Astrophysics Data System (ADS)

    Gladden-Green, Dannellia Banay

    Technological advancements of novel processes and materials involving refractory metal silicides for ultra large scale integration is of paramount importance to the semiconductor industry. Scaling of devices to meet the demands for increased packing density and speed requires such novel processes and materials. Rapid thermal chemical vapor deposition (RTCVD) of titanium disilicide (TiSisb2) was investigated in an effort to meet some of the challenges of ultra large scale integration (ULSI) technology. Selective RTCVD of TiSisb2 offers an optimal technological vehicle for achieving contacts to ultra-shallow junctions. Of all of the metal silicides, TiSisb2 has the lowest resistivity and meets the microelectronics demands for a thermally stable contact. The research results presented in this dissertation explores the mechanisms of selective RTCVD of TiSisb2 in terms of thermodynamic trends and kinetic driving forces for nucleation and growth. The present research addresses the qualitative and quantitative parameters that affect the controlling mechanisms for nucleation and therefore the results provide significant data and theoretical insights into a state-of-the-art process. Just as the fundamental building block in understanding the kinetic constraints of a process lie in the realm of thermodynamic exploration, understanding the complex processes involved in RTCVD TiSisb2 begin with characterization of the mechanisms governing thin film nucleation. In this work, the early stages of growth are investigated as they offer insight into how process parameters are optimized to render desired silicide film properties. Equilibrium simulations have been used to model the CVD reaction with very good trend indicating accuracy. Empirical investigations of CVD TiSisb2 took place in a low-pressure rapid-thermal environment using the SiHsb4 + TiClsb4 gas system on silicon (100) substrates. Secondary ion mass spectroscopy (SIMS) has been used to qualify the benefits of vacuum and

  3. Model reduction and temperature uniformity control for rapid thermal chemical vapor deposition reactors

    NASA Astrophysics Data System (ADS)

    Theodoropoulou, Artemis-Georgia

    The consideration of Rapid Thermal Processing (RTP) in semiconductor manufacturing has recently been increasing. As a result, control of RTP systems has become of great importance since it is expected to help in addressing uniformity problems that, so far, have been obstructing the acceptance of the method. The spatial distribution appearing in RTP models necessitates the use of model reduction in order to obtain models of a size suitable for use in control algorithms. This dissertation addresses model reduction as well as control issues for RTP systems. A model of a three-zone Rapid Thermal Chemical Vapor Deposition (RTCVD) system is developed to study the effects of spatial wafer temperature patterns on polysilicon deposition uniformity. A sequence of simulated runs is performed, varying the lamp power profiles so that different wafer temperature modes are excited. The dominant spatial wafer thermal modes are extracted via Proper Orthogonal Decomposition and subsequently used as a set of trial functions to represent both the wafer temperature and deposition thickness. A collocation formulation of Galerkin's method is used to discretize the original modeling equations, giving a low-order model which loses little of the original, high-order model's fidelity. We make use of the excellent predictive capabilities of the reduced model to optimize power inputs to the lamp banks to achieve a desired polysilicon deposition thickness at the end of a run with minimal deposition spatial nonuniformity. Since the results illustrate that the optimization procedure benefits from the use of the reduced-order model, we further utilize the reduced order model for real time Model Based Control. The feedback controller is designed using the Internal Model Control (IMC) structure especially modified to handle systems described by ordinary differential and algebraic equations. The IMC controller is obtained using optimal control theory on singular arcs extended for multi input systems

  4. Selective rapid thermal chemical vapor deposition of titanium silicide on heavily doped silicon

    NASA Astrophysics Data System (ADS)

    Fang, Hua

    The continued scaling of Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) increases the need for advanced contact formation technologies that can be used on ultra-shallow source and drain junctions. Titanium silicide (TiSi2) formed by the Self-Aligned Silicide (SALICIDE) technology is widely used in MOSFET fabrication for this purpose. As device feature sizes shrink down to 0.1 mum, however, the SALICIDE technology becomes increasingly incompatible with ultra-shallow junctions because of silicon substrate consumption. For TiSi2, achieving the low resistivity C54 phase on narrow polycrystalline silicon lines (<0.2 mum) is also quite challenging. This work focused on selective rapid thermal chemical vapor deposition (RTCVD) of TiSi2 on heavily-doped single-crystal substrates and polycrystalline films. As the gaseous precursors, SiH4 and TiCl 4 were used. The main objective of this work was to understand the impact of dopants on TiSi2 nucleation and substrate consumption in order to achieve C54-TiSi2 deposition with negligible consumption on heavily doped p- and n-type Si. In this work, TiSi2 deposition was found to be quite sensitive to both dopant type and amount. While boron doping did not interfere with TiSi2 deposition, arsenic introduced a barrier to nucleation and increased substrate consumption. These effects were linked to surface passivation before and during deposition. Arsenic was found to diffuse into the TiSi2 layer maintaining a high surface concentration during deposition. Phosphorus also showed effects similar to arsenic but these effects were much less severe and could be suppressed by raising the process temperature. To suppress the undesirable effects, different pre-deposition surface treatments were considered. The rationale behind these treatments was to remove the arsenic passivated surface layer without giving arsenic atoms the chance to replenish the surface sites. The surface treatments considered were in-situ Cl2 etching and in

  5. Rapid determination of the chemical oxygen demand of water using a thermal biosensor.

    PubMed

    Yao, Na; Wang, Jinqi; Zhou, Yikai

    2014-06-06

    In this paper we describe a thermal biosensor with a flow injection analysis system for the determination of the chemical oxygen demand (COD) of water samples. Glucose solutions of different concentrations and actual water samples were tested, and their COD values were determined by measuring the heat generated when the samples passed through a column containing periodic acid. The biosensor exhibited a large linear range (5 to 3000 mg/L) and a low detection limit (1.84 mg/L). It could tolerate the presence of chloride ions in concentrations of 0.015 M without requiring a masking agent. The sensor was successfully used for detecting the COD values of actual samples. The COD values of water samples from various sources were correlated with those obtained by the standard dichromate method; the linear regression coefficient was found to be 0.996. The sensor is environmentally friendly, economical, and highly stable, and exhibits good reproducibility and accuracy. In addition, its response time is short, and there is no danger of hazardous emissions or external contamination. Finally, the samples to be tested do not have to be pretreated. These results suggest that the biosensor is suitable for the continuous monitoring of the COD values of actual wastewater samples.

  6. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    SciTech Connect

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  7. Chemical nature of silicon nitride-indium phosphide interface and rapid thermal annealing for InP MISFETs

    NASA Technical Reports Server (NTRS)

    Biedenbender, M. D.; Kapoor, V. J.

    1990-01-01

    A rapid thermal annealing (RTA) process in pure N2 or pure H2 was developed for ion-implanted and encapsulated indium phosphide compound semiconductors, and the chemical nature at the silicon nitride-InP interface before and after RTA was examined using XPS. Results obtained from SIMS on the atomic concentration profiles of the implanted silicon in InP before and after RTA are presented, together with electrical characteristics of the annealed implants. Using the RTA process developed, InP metal-insulator semiconductor FETs (MISFETS) were fabricated. The MISFETS prepared had threshold voltages of +1 V, transconductance of 27 mS/mm, peak channel mobility of 1200 sq cm/V per sec, and drain current drift of only 7 percent.

  8. Chemical nature of silicon nitride-indium phosphide interface and rapid thermal annealing for InP MISFETs

    NASA Technical Reports Server (NTRS)

    Biedenbender, M. D.; Kapoor, V. J.

    1990-01-01

    A rapid thermal annealing (RTA) process in pure N2 or pure H2 was developed for ion-implanted and encapsulated indium phosphide compound semiconductors, and the chemical nature at the silicon nitride-InP interface before and after RTA was examined using XPS. Results obtained from SIMS on the atomic concentration profiles of the implanted silicon in InP before and after RTA are presented, together with electrical characteristics of the annealed implants. Using the RTA process developed, InP metal-insulator semiconductor FETs (MISFETS) were fabricated. The MISFETS prepared had threshold voltages of +1 V, transconductance of 27 mS/mm, peak channel mobility of 1200 sq cm/V per sec, and drain current drift of only 7 percent.

  9. Fast synthesis of high-performance graphene films by hydrogen-free rapid thermal chemical vapor deposition.

    PubMed

    Ryu, Jaechul; Kim, Youngsoo; Won, Dongkwan; Kim, Nayoung; Park, Jin Sung; Lee, Eun-Kyu; Cho, Donyub; Cho, Sung-Pyo; Kim, Sang Jin; Ryu, Gyeong Hee; Shin, Hae-A-Seul; Lee, Zonghoon; Hong, Byung Hee; Cho, Seungmin

    2014-01-28

    The practical use of graphene in consumer electronics has not been demonstrated since the size, uniformity, and reliability problems are yet to be solved to satisfy industrial standards. Here we report mass-produced graphene films synthesized by hydrogen-free rapid thermal chemical vapor deposition (RT-CVD), roll-to-roll etching, and transfer methods, which enabled faster and larger production of homogeneous graphene films over 400 × 300 mm(2) area with a sheet resistance of 249 ± 17 Ω/sq without additional doping. The properties of RT-CVD graphene have been carefully characterized by high-resolution transmission electron microscopy, Raman spectroscopy, chemical grain boundary analysis, and various electrical device measurements, showing excellent uniformity and stability. In particular, we found no significant correlation between graphene domain sizes and electrical conductivity, unlike previous theoretical expectations for nanoscale graphene domains. Finally, the actual application of the RT-CVD films to capacitive multitouch devices installed in the most sophisticated mobile phone was demonstrated.

  10. Modeling and experimentation in the chemical vapor deposition of silicon in a single wafer rapid thermal system

    SciTech Connect

    Toprac, A.J.

    1992-01-01

    The chemical vapor deposition of polysilicon from thermally activated silane in a cold wall, single wafer rapid thermal system was studied by both experimentation and mathematical modeling. Experimental deposition rates were obtained at a variety of conditions, including very high temperatures. While there is no practical benefit from polysilicon films produced at such high temperatures, the deposition data at these conditions produced insight into the nature of the silane surface reactions. As temperature increased, the apparent activation energy of polysilicon deposition decreased, as has been observed by other investigators in measurements of the silane reactive sticking coefficient. In addition to this previously reported effect, at very high temperatures a decrease in deposition rate with temperature increase was observed. This new finding, coupled with an experimental observation of polysilicon film decomposition at high temperature in inert ambient, allowed a fundamental insight of polysilicon deposition as the net result of competing forward and reverse silane surface reaction rates. Based on this insight, classic chemical engineering methods of characterizing catalytic surface reactions were used to produce an empirical fit which describes very well the complex behavior seen in the deposition data. A model of mass transfer in polysilicon deposition was developed using the new silane surface reaction rate expression. This model gave excellent predictions of polysilicon deposition data both in absolute rates and deposition uniformity across the wafer. The model was formulated with an absence of gas phase reactions, which were definitively shown to be negligible in contributing to the overall deposition rate by a separate model of the gas phase chemistry. Finally, modeling of the flow field in the reactor chamber furnished insight into principles of good single wafer reactor chamber design.

  11. Low resistance tungsten films on GaAs deposited by means of rapid thermal low pressure chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Katz, A.; Feingold, A.; Nakahara, S.; Pearton, S. J.; Lane, E.

    1992-08-01

    Low resistance tungsten (W) films were deposited onto GaAs substrates by means of rapid thermal low pressure chemical vapor deposition (RT-LPCVD), using tungsten hexafluoride (WF6) gas reduced by hydrogen (H2). Deposition temperatures up to 550 °C for durations of up to 30 s were explored, resulting in deposition of relatively pure W films (containing less than 2% O2 and C). Post-deposition sintering of the layers led to significant reduction of the resistivity to values as low as 50 μΩ cm. The efficiency of the deposition improved upon increasing the H2 flow rate up to 1250 sccm resulting in a deposition rate of about 10 nm/s at a total chamber pressure of 3.5 Torr and temperature of 500 °C. The films appeared to be polycrystalline with a very fine grain structure, regardless of the deposition temperature with good morphology and underwent a limited reaction with the underlying GaAs substrates.

  12. Low thermal budget in situ removal of oxygen and carbon on silicon for silicon epitaxy in an ultrahigh vacuum rapid thermal chemical vapor deposition reactor

    NASA Astrophysics Data System (ADS)

    Sanganeria, Mahesh K.; Öztürk, Mehmet C.; Violette, Katherine E.; Harris, Gari; Lee, C. Archie; Maher, Dennis M.

    1995-03-01

    In this letter, we present experimental evidence on desorption of O and C from a Si surface resulting in impurity levels below the detection levels of secondary ion mass spectroscopy. We then propose a surface preperation method for silicon epitaxy that consists of an ex situ clean and an in situ low thermal budget prebake in an ultrahigh vacuum rapid thermal chemical vapor deposition (UHV-RTCVD) reactor. The ex situ clean consists of a standard RCA clean followed by a dilute HF dip and rinse in de-ionized water. The in situ clean is either carried out in vacuum or in a low partial pressure of 10% Si2H6 in H2. The experiments were conducted in an UHV-RTCVD reactor equipped with oil-free vacuum pumps. We propose that the responsible mechanism is desorption of oxygen and hydrocarbons from the Si surface due to the low partial pressures of these contaminants in the growth chamber. If Si2H6 is used during the prebake, a sufficiently low growth rate is required in order to provide sufficient time for desorption and avoid Si overgrowth on the O and C sites.

  13. Correlation between the temperature dependence of intrinsic MR parameters and thermal dose measured by a rapid chemical shift imaging technique.

    PubMed

    Taylor, B A; Elliott, A M; Hwang, K P; Hazle, J D; Stafford, R J

    2011-12-01

    In order to investigate simultaneous MR temperature imaging and direct validation of tissue damage during thermal therapy, temperature-dependent signal changes in proton resonance frequency (PRF) shifts, R(2)* values, and T1-weighted amplitudes are measured from one technique in ex vivo tissue. Using a multigradient echo acquisition and the Stieglitz-McBride algorithm, the temperature sensitivity coefficients of these parameters are measured in each tissue at high spatiotemporal resolutions (1.6 x 1.6 x 4 mm 3,≤ 5sec) at the range of 25-61 °C. Non-linear changes in MR parameters are examined and correlated with an Arrhenius rate dose model of thermal damage. Using logistic regression, the probability of changes in these parameters is calculated as a function of thermal dose to determine if changes correspond to thermal damage. Temperature sensitivity of R(2)* and, in some cases, T1-weighted amplitudes are statistically different before and after thermal damage occurred. Significant changes in the slopes of R(2)* as a function of temperature are observed. Logistic regression analysis shows that these changes could be accurately predicted using the Arrhenius rate dose model (Ω = 1.01 ± 0.03), thereby showing that the changes in R(2)* could be direct markers of protein denaturation. Overall, by using a chemical shift imaging technique with simultaneous temperature estimation, R(2)* mapping and T1-W imaging, it is shown that changes in the sensitivity of R(2)* and, to a lesser degree, T1-W amplitudes are measured in ex vivo tissue when thermal damage is expected to occur. These changes could possibly be used for direct validation of thermal damage in contrast to model-based predictions. Copyright © 2011 John Wiley & Sons, Ltd.

  14. Correlation between the Temperature Dependence of Intrsinsic Mr Parameters and Thermal Dose Measured by a Rapid Chemical Shift Imaging Technique

    PubMed Central

    Taylor, Brian A.; Elliott, Andrew M.; Hwang, Ken-Pin; Hazle, John D.; Stafford, R. Jason

    2011-01-01

    In order to investigate simultaneous MR temperature imaging and direct validation of tissue damage during thermal therapy, temperature-dependent signal changes in proton resonance frequency (PRF) shifts, R2* values, and T1-weighted amplitudes are measured from one technique in ex vivo tissue heated with a 980-nm laser at 1.5T and 3.0T. Using a multi-gradient echo acquisition and signal modeling with the Stieglitz-McBride algorithm, the temperature sensitivity coefficient (TSC) values of these parameters are measured in each tissue at high spatiotemporal resolutions (1.6×1.6×4mm3,≤5sec) at the range of 25-61 °C. Non-linear changes in MR parameters are examined and correlated with an Arrhenius rate dose model of thermal damage. Using logistic regression, the probability of changes in these parameters is calculated as a function of thermal dose to determine if changes correspond to thermal damage. Temperature calibrations demonstrate TSC values which are consistent with previous studies. Temperature sensitivity of R2* and, in some cases, T1-weighted amplitudes are statistically different before and after thermal damage occurred. Significant changes in the slopes of R2* as a function of temperature are observed. Logistic regression analysis shows that these changes could be accurately predicted using the Arrhenius rate dose model (Ω=1.01±0.03), thereby showing that the changes in R2* could be direct markers of protein denaturation. Overall, by using a chemical shift imaging technique with simultaneous temperature estimation, R2* mapping and T1-W imaging, it is shown that changes in the sensitivity of R2* and, to a lesser degree, T1-W amplitudes are measured in ex vivo tissue when thermal damage is expected to occur according to Arrhenius rate dose models. These changes could possibly be used for direct validation of thermal damage in contrast to model-based predictions. PMID:21721063

  15. Physico-chemical and electrical properties of rapid thermal oxides on Ge-rich SiGe heterolayers

    NASA Astrophysics Data System (ADS)

    Das, R.; Bera, M. K.; Chakraborty, S.; Saha, S.; Woitok, J. F.; Maiti, C. K.

    2006-11-01

    Rapid thermal oxidation of high-Ge content (Ge-rich) Si 1- xGe x ( x = 0.85) layers in dry O 2 ambient has been investigated. High-resolution X-ray diffraction (HRXRD) and strain-sensitive two-dimensional reciprocal space mapping X-ray diffractometry (2D-RSM) are employed to investigate strain relaxation and composition of as-grown SiGe alloy layers. Characterizations of ultra thin oxides (˜6-8 nm) have been performed using Fourier transform infrared spectroscopy (FTIR) and high-resolution X-ray photoelectron spectroscopy (HRXPS). Formation of mixed oxide i.e., (SiO 2 + GeO 2) and pile-up of Ge at the oxide/Si 1- xGe x interface have been observed. Enhancement in Ge segregation and reduction of oxide thickness with increasing oxidation temperature are reported. Interface properties and leakage current behavior of the rapid thermal oxides have been studied by capacitance-voltage (C-V) and current-voltage (J-V) techniques using metal-oxide-semiconductor capacitor (MOSCAP) structures and the results are reported.

  16. Rapid processing of carbon-carbon composites by forced flow-thermal gradient chemical vapor infiltration (FCVI)

    SciTech Connect

    Vaidyaraman, S.; Lackey, W.J.; Agrawal, P.K.; Freeman, G.B.; Langman, M.D.

    1995-10-01

    Carbon fiber-carbon matrix composites were fabricated using the forced flow-thermal gradient chemical vapor infiltration (FCVI) process. Preforms were prepared by stacking 40 layers of plain weave carbon cloth in a graphite holder. The preforms were infiltrated using propylene, propane, and methane. The present work showed that the FCVI process is well suited for fabricating carbon-carbon composites; without optimization of the process, the authors have achieved uniform and thorough densification. Composites with porosities as low as 7% were fabricated in 8--12 h. The highest deposition rate obtained in the present study was {approximately}3 {micro}m/h which is more than an order of magnitude faster than the typical value of 0.1--0.25 {micro}m/h for the isothermal process. It was also found that the use of propylene and propane as reagents resulted in faster infiltration compared to methane.

  17. Rapid thermal processing by stamping

    DOEpatents

    Stradins, Pauls; Wang, Qi

    2013-03-05

    A rapid thermal processing device and methods are provided for thermal processing of samples such as semiconductor wafers. The device has components including a stamp (35) having a stamping surface and a heater or cooler (40) to bring it to a selected processing temperature, a sample holder (20) for holding a sample (10) in position for intimate contact with the stamping surface; and positioning components (25) for moving the stamping surface and the stamp (35) in and away from intimate, substantially non-pressured contact. Methods for using and making such devices are also provided. These devices and methods allow inexpensive, efficient, easily controllable thermal processing.

  18. Tungsten metallization onto InP prepared by rapid thermal low-pressure chemical vapor deposition of WF6 and H2

    NASA Astrophysics Data System (ADS)

    Katz, A.; Feingold, A.; El-Roy, A.; Pearton, S. J.; Lane, E.; Nakahara, S.; Geva, M.

    1992-09-01

    Tungsten (W) films were deposited onto InP in a cold wall, rapid thermal low-pressure chemical vapor deposition (RT-LPCVD) reactor, using a tungsten hexafluoride (WF6) gas reduced by hydrogen (H2). W films of thickness 50-450 nm were deposited in the temperature range of 350-550 °C, pressure range of 0.5-4.5 Torr, and deposition rates up to 4 nm/s with an apparent activation energy of about 1.12 eV. The film stress varied depending on the deposition pressure, from low compressive (deposition at 0.5 Torr) to moderate tensile (deposition at about 4.5 Torr). Post-deposition sintering of the W films at temperatures up to 600 °C led to reduction of the resistivity with a minimum value of about 55 μΩ cm as a result of heating at 500 °C.

  19. Chemical and Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Bulluck, J. W.; Rushing, R. A.

    1994-01-01

    Thermal decomposition activation energies have been determined using two methods of Thermogravimetric Analysis (TGA), with good correlation being obtained between the two techniques. Initial heating curves indicated a two-component system for Coflon (i.e. polymer plus placticizer) but a single component system for Tefzel. Two widely differing activation energies were for Coflon supported this view, 15 kcl/mol being associated with plasticizer, and 40 kcal/mol with polymer degradation. With Tefzel, values were 40-45 kcal/mol, the former perhaps being associated with a low molecular weight fraction. Appropriate acceleration factors have been determined. Thermomechanical Analysis (TMA) has shown considerable dimensional change during temperature cycles. For unaged pipe sections heating to 100 C and then holding the temperature resulted in a stable thickness increase of 2%, whereas the Coflon thickness decreased continuously, reaching -4% in 2.7 weeks. Previously strained tensile bars of Tefzel expanded on cooling during TMA. SEM performed on H2S-aged Coflon samples showed significant changes in both physical and chemical nature. The first may have resulted from explosive decompression after part of the aging process. Chemically extensive dehydrofluorination was indicated, and sulfur was present as a result of the aging. These observations indicate that chemical attack of PVDF can occur in some circumstances.

  20. ZnO nanorod arrays prepared by chemical bath deposition combined with rapid thermal annealing: structural, photoluminescence and field emission characteristics

    NASA Astrophysics Data System (ADS)

    Chen, Hung-Wei; Yang, Hsi-Wen; He, Hsin-Min; Lee, Yi-Mu

    2016-01-01

    ZnO nanorod arrays were prepared by low temperature chemical bath deposition (CBD) combined with rapid thermal annealing (RTA) under different ambient conditions. The structure and morphology of the synthesized ZnO have been characterized by field-emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). The obtained ZnO samples are highly crystalline with a hexagonal wurtzite phase and also display well-aligned array structure. A pronounced effect on increased nanorod length was found for the RTA-treated ZnO as compared to the as-grown ZnO. Analysis of XRD indicates that the (0 0 2) feature peak of the as-grown ZnO was shifted towards a lower angle as compared to the peaks of RTA-treated ZnO samples due to the reduction of tensile strain along the c-axis by RTA. Photoluminescence (PL) studies reveal that the ZnO nanorod arrays receiving RTA in an O2 environment have the sharpest UV emission band and greatest intensity ratio of near band-edge emission (NBE) to deep level emission (DLE). Additionally, the effects of RTA on the field emission properties were evaluated. The results demonstrate that RTA an O2 environment can lower the turn-on field and improve the field enhancement factor. The stability of the field emission current was also tested for 4 h.

  1. Rapid thermal low-pressure chemical vapour deposition of tungsten films onto InP using WF6 and H2

    NASA Astrophysics Data System (ADS)

    Katz, A.; Feingold, A.; El-Roy, A.; Pearton, S. J.; Lane, E.; Nakahara, S.; Geva, M.

    1992-11-01

    Tungsten (W) films were deposited onto InP in a cold wall, rapid thermal low-pressure chemical vapour deposition (RT-LPCVD) reactor, from a tungsten hexafluoride (WF6) gas reduced by hydrogen (H2). W films of thickness 50-450 nm were deposited in the temperature range 350-550 degrees C, pressure range 0.5-4.5 Torr at deposition rates up to 4 nm s-1 with an apparent activation energy of about 1.12 eV. The film stress varied depending upon the deposition pressure, from low compressive for deposition at 0.5 Torr to moderate tensile for deposition at about 4.5 Torr. The films were aged at temperatures as high as 300 degrees C for about 800 h and exhibited an excellent mechanical stability. Post-deposition sintering of the W films at temperatures up to 600 degrees C led to reduction of the resistivity with a minimum value of about 55 mu Omega cm as a result of heating at 500 degrees C. Conditions for both selective and blanket deposition were defined, and a dry etching process for further geometrical definitions of the films was developed, providing etch rates of 40-50 nm min-1. This report reflects the first attempt to deposit W films onto III-V semiconductor at a very high rate by means of RT-LPCVD.

  2. Chemical and Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Bulluck, J. W.; Rushing, R. A.; Thornton, C. P.

    1996-01-01

    Work has included significant research in several areas aimed at further clarification of the aging and chemical failure mechanism of thermoplastics (PVDF or Tefzel) for pipes. Among the areas investigated were the crystallinity changes associated with both the Coflon and Tefzel after various simulated environmental exposures using X-Ray diffraction analysis. We have found that significant changes in polymer crystallinity levels occur as a function of the exposures. These crystallinity changes may have important consequences on the fracture, fatigue, tensile, and chemical resistance of the materials. We have also noted changes in the molecular weight distribution of the Coflon material using a dual detector Gel Permeation Analysis. Again these changes may result in variation in the mechanical and chemical properties in the material. We conducted numerous analytical studies with methods including X-Ray Diffraction, Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry. We investigated a number of aged samples of both Tefzel and Coflon that were forwarded from MERL. Pressurized tests were performed in a modified Fluid G, which we will call G2. In this case the ethylene diamine concentration was increased to 3 percent in methanol. Coflon pipe sections and powdered Coflon were exposed in pressure cells at 1700 psi at three separate test temperatures, 70 C, 110 C, and 130 C. The primary purpose of the pressure tests in Fluid G2 was to further elucidate the aging mechanism of PVDF degradation.

  3. Chemical and Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Bulluck, J. W.; Rushing, R. A.

    1997-01-01

    Work during the past three years has included significant research in several areas aimed at further clarification of the aging and chemical failure mechanism of thermoplastics (PVDF or Tefzel) for pipes. Among the areas investigated were the crystallinity changes associated with both the Coflon and Tefzel after various simulated environmental exposures using X-Ray diffraction analysis. We have found that significant changes in polymer crystallinity levels occur as a function of the exposures. These crystallinity changes may have important consequences on the fracture, fatigue, tensile, and chemical resistance of the materials. We have also noted changes in the molecular weight distribution and the increased crosslinking of the Coflon material using Gel Permeation Chromatographic Analysis. Again these changes may result in variations in the mechanical and chemical properties in the material. We conducted numerous analytical studies with methods including X-ray Diffraction, Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, and Differential Scanning Calorimetry. We investigated a plethora of aged samples of both Tefzel and Coflon that were forwarded from MERL. Pressurized tests were performed on powdered PVDF in a modified Fluid A, which we will call A-2. In this case the ethylene diamine concentration was increased to 3 percent in methanol. Coflon pipe sections and powdered Coflon were exposed in pressure cells at 1700 psi at three separate test temperatures.

  4. Rapid Chemical Exposure and Dose Research

    EPA Pesticide Factsheets

    EPA evaluates the potential risks of the manufacture and use of thousands of chemicals. To assist with this evaluation, EPA scientists developed a rapid, automated model using off the shelf technology that predicts exposures for thousands of chemicals.

  5. Chemical and Thermal Analysis

    NASA Technical Reports Server (NTRS)

    Bulluck, J. W.; Rushing, R. A.

    1995-01-01

    During the past six months we have conducted significant research in several domains in order to clarify and understanding the aging and chemical failure mechanism of thermoplastics (PVDF or Tefzel) for pipes. We organized numerous analytical studies with methods including Fourier Transform Infrared Spectroscopy, Dynamic Mechanical Analysis, Differential Scanning Calorimetry, and Stress Relaxation experiments. In addition we have reanalyzed previous thermogravimetric data concerning the rate of deplasticization of Coflon pipe. We investigated a number of aged samples of both Tefzel and Coflon that were forwarded from MERL. We conducted stress relaxation experiments of Coflon pipe at several temperatures and determined an activation energy. We also examined the dynamic mechanical response PVDF during deplasticization and during methanol plasticization. We performed numerous DSC analyses to research the changing crystalline morphology. We have noted significant changes in crystallinity upon aging for both PVDF and Tefzel. Little variation in elemental composition was noted for many of the aged Coflon and Tefzel samples tested.

  6. Ceramic thermal barrier coating for rapid thermal cycling applications

    DOEpatents

    Scharman, Alan J.; Yonushonis, Thomas M.

    1994-01-01

    A thermal barrier coating for metal articles subjected to rapid thermal cycling includes a metallic bond coat deposited on the metal article, at least one MCrAlY/ceramic layer deposited on the bond coat, and a ceramic top layer deposited on the MCrAlY/ceramic layer. The M in the MCrAlY material is Fe, Ni, Co, or a mixture of Ni and Co. The ceramic in the MCrAlY/ceramic layer is mullite or Al.sub.2 O.sub.3. The ceramic top layer includes a ceramic with a coefficient of thermal expansion less than about 5.4.times.10.sup.-6 .degree.C.sup.-1 and a thermal conductivity between about 1 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1 and about 1.7 J sec.sup.-1 m.sup.-1 .degree.C.sup.-1.

  7. Thermal and chemical convection in planetary mantles

    NASA Technical Reports Server (NTRS)

    Dupeyrat, L.; Sotin, C.; Parmentier, E. M.

    1995-01-01

    Melting of the upper mantle and extraction of melt result in the formation of a less dense depleted mantle. This paper describes series of two-dimensional models that investigate the effects of chemical buoyancy induced by these density variations. A tracer particles method has been set up to follow as closely as possible the chemical state of the mantle and to model the chemical buoyant force at each grid point. Each series of models provides the evolution with time of magma production, crustal thickness, surface heat flux, and thermal and chemical state of the mantle. First, models that do not take into account the displacement of plates at the surface of Earth demonstrate that chemical buoyancy has an important effect on the geometry of convection. Then models include horizontal motion of plates 5000 km wide. Recycling of crust is taken into account. For a sufficiently high plate velocity which depends on the thermal Rayleigh number, the cell's size is strongly coupled with the plate's size. Plate motion forces chemically buoyant material to sink into the mantle. Then the positive chemical buoyancy yields upwelling as depleted mantle reaches the interface between the upper and the lower mantle. This process is very efficient in mixing the depleted and undepleted mantle at the scale of the grid spacing since these zones of upwelling disrupt the large convective flow. At low spreading rates, zones of upwelling develop quickly, melting occurs, and the model predicts intraplate volcanism by melting of subducted crust. At fast spreading rates, depleted mantle also favors the formation of these zones of upwelling, but they are not strong enough to yield partial melting. Their rapid displacement toward the ridge contributes to faster large-scale homogenization.

  8. Thermal and chemical convection in planetary mantles

    NASA Technical Reports Server (NTRS)

    Dupeyrat, L.; Sotin, C.; Parmentier, E. M.

    1995-01-01

    Melting of the upper mantle and extraction of melt result in the formation of a less dense depleted mantle. This paper describes series of two-dimensional models that investigate the effects of chemical buoyancy induced by these density variations. A tracer particles method has been set up to follow as closely as possible the chemical state of the mantle and to model the chemical buoyant force at each grid point. Each series of models provides the evolution with time of magma production, crustal thickness, surface heat flux, and thermal and chemical state of the mantle. First, models that do not take into account the displacement of plates at the surface of Earth demonstrate that chemical buoyancy has an important effect on the geometry of convection. Then models include horizontal motion of plates 5000 km wide. Recycling of crust is taken into account. For a sufficiently high plate velocity which depends on the thermal Rayleigh number, the cell's size is strongly coupled with the plate's size. Plate motion forces chemically buoyant material to sink into the mantle. Then the positive chemical buoyancy yields upwelling as depleted mantle reaches the interface between the upper and the lower mantle. This process is very efficient in mixing the depleted and undepleted mantle at the scale of the grid spacing since these zones of upwelling disrupt the large convective flow. At low spreading rates, zones of upwelling develop quickly, melting occurs, and the model predicts intraplate volcanism by melting of subducted crust. At fast spreading rates, depleted mantle also favors the formation of these zones of upwelling, but they are not strong enough to yield partial melting. Their rapid displacement toward the ridge contributes to faster large-scale homogenization.

  9. Rapid thermal conditioning of sewage sludge

    NASA Astrophysics Data System (ADS)

    Zheng, Jianhong

    Rapid thermal conditioning (RTC) is a developing technology recently applied to sewage sludge treatment. Sludge is heated rapidly to a reaction temperature (up to about 220sp°C) under sufficient pressure to maintain the liquid phase. Reaction is quenched after 10 to 30 seconds when the mixture of sludge and steam pass through a pressure let-down valve. This process reduces the amount of sludge requiring land disposal, eliminates the need for polymer coagulant, improves dewaterability, increases methane production, and further reduces the concentration of pathogens. The odor problem associated with traditional thermal conditioning processes is largely minimized. Ammonia removal is readily integrated with the process. For this research, a pilot unit was constructed capable of processing 90 liters of sludge per hour. Over 22 runs were made with this unit using sludge from New York City Water Pollution Control Plants (WPCP). Sludges processed in this equipment were tested to determine the effect of RTC operating conditions on sludge dewaterability, biodegradability, and other factors affecting the incorporation of RTC into wastewater treatment plants. Dewaterability of thermally conditioned sludge was assessed for cetrifugeability and filterability. Bench scale centrifugation was used for evaluating centrifugeability, pressure filtration and capillary suction time (CST) for filterability. A mathematical model developed for centrifuge dewatering was used to predict the effect of RTC on full scale centrifuge performance. Particle size distribution and solids density of raw and treated PDS were also analyzed. An observed increase in sludge solids density at least partially explains its improved centrifugeability. An investigation of thermally conditioned amino acids showed that the L-isomer is highly biodegradable while the D-isomers are generally less so. Glucose is highly biodegradable, but rapidly becomes refractory as thermal conditioning time is lengthened. This

  10. Methods and compositions for rapid thermal cycling

    DOEpatents

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher

    2015-10-27

    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  11. Low Gravity Rapid Thermal Analysis of Glass

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Ethridge, Edwin C.; Smith, Guy A.

    2004-01-01

    It has been observed by two research groups that ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass crystallization is suppressed in microgravity. The mechanism for this phenomenon is unknown at the present time. In order to better understand the mechanism, an experiment was performed on NASA's KC135 reduced gravity aircraft to obtain quantitative crystallization data. An apparatus was designed and constructed for performing rapid thermal analysis of milligram quantities of ZBLAN glass. The apparatus employs an ellipsoidal furnace allowing for rapid heating and cooling. Using this apparatus nucleation and crystallization kinetic data was obtained leading to the construction of time-temperature-transformation curves for ZBLAN in microgravity and unit gravity.

  12. [Chemical and Thermal Eye Burns].

    PubMed

    Struck, H-G

    2016-11-01

    Background: This review gives a therapeutic approach for the early treatment of chemical and thermal burns of the ocular surface (CTOS). Method: Based on a review of international literature, the experiences of University Hospital Aachen and Halle/Saale, Eye Clinic Cologne as well as experimental data of the research institute (An-Institut) at RWTH Aachen University are considered and discussed. Results: As the risk depends on the stage of CTOS, recommendations are given for acute treatment for different stages. Pathophysiological considerations will be discussed. Special treatment options for exceptional situations and for late phase CTOS are demonstrated. Conclusion: According to the latest data, the most important clinical recommendation for the acute phase of CTOS is the application of a suitable rinsing solution. Furthermore, anti-inflammatory treatment is of central importance. For the therapy of severe CTOS, approved and advanced surgical methods need to be applied. In this way, anti-inflammatory and tissue-protecting mechanisms are activated simultaneously. Georg Thieme Verlag KG Stuttgart · New York.

  13. Chemical preconcentrator with integral thermal flow sensor

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2003-01-01

    A chemical preconcentrator with integral thermal flow sensor can be used to accurately measure fluid flow rate in a microanalytical system. The thermal flow sensor can be operated in either constant temperature or constant power mode and variants thereof. The chemical preconcentrator with integral thermal flow sensor can be fabricated with the same MEMS technology as the rest of the microanlaytical system. Because of its low heat capacity, low-loss, and small size, the chemical preconcentrator with integral thermal flow sensor is fast and efficient enough to be used in battery-powered, portable microanalytical systems.

  14. RTDS: A continuous, rapid, thermal synthesis mode

    SciTech Connect

    Matson, D.W.; Linehan, J.C.; Darab, J.D.; Buehler, M.F.; Phelps, M.R.; Neuenschwander, G.G.

    1995-04-01

    The Rapid Thermal Decomposition of precursors in Solution (RTDS) Process is a flow-through hydrothermal powder synthesis method capable of producing nanophase oxide and oxyhydroxide catalysts and catalyst precursors. The RTDS technique utilizes a brief exposure of dissolved precursors to high pressure/high temperature aqueous conditions to initiate crystallite nucleation. The resulting nanocrystalline suspension is removed from the hydrothermal environment through a pressure let-down device before significant crystallite growth can occur. The RTDS process is discussed as a method to produce nanocrystalline iron oxide and oxyhydroxide powders that exhibit high activity as carbon-carbon bond cleavage catalyst precursors. Nanocrystalline TiO{sub 2} and ZrO{sub 2} powders having prospective catalytic applications are also produced by the RTDS process.

  15. Chemical Stockpile Disposal Program rapid accident assessment

    SciTech Connect

    Chester, C.V.

    1990-08-01

    This report develops a scheme for the rapid assessment of a release of toxic chemicals resulting from an accident in one of the most chemical weapon demilitarization plants or storage areas. The system uses such inputs as chemical and pressure sensors monitoring the plant and reports of accidents radioed to the Emergency Operations Center by work parties or monitoring personnel. A size of release can be estimated from previous calculations done in the risk analysis, from back calculation from an open-air chemical sensor measurement, or from an estimated percentage of the inventory of agent at the location of the release. Potential consequences of the estimated release are calculated from real-time meteorological data, surrounding population data, and properties of the agent. In addition to the estimated casualties, area coverage and no-death contours vs time would be calculated. Accidents are assigned to one of four categories: community emergencies, which are involve a threat to off-site personnel; on-post emergencies, which involve a threat only to on-site personnel; advisory, which involves a potential for threat to on-site personnel; and chemical occurrence, which can produce an abnormal operating condition for the plant but no immediate threat to on-site personnel. 9 refs., 20 tabs.

  16. Rapid thermal oxidation of silicon in ozone

    NASA Astrophysics Data System (ADS)

    Cui, Zhenjiang; Madsen, Jonathan M.; Takoudis, Christos G.

    2000-06-01

    Rapid thermal oxidation (RTO) of Si in ozone gas is studied at temperatures between 200 and 550 °C, and the properties of the resulting ultrathin oxides are characterized using in situ mirror-enhanced reflection Fourier transform infrared (IR) spectroscopy. Thus, the frequency and intensity of the longitudinal optical vibrational mode of the Si-O-Si asymmetric stretching from ultrathin oxide films (<30 Å) are probed in different processing environments and related to the oxidation kinetics and interfacial layer properties. The oxidation rate in ozone is found to be comparable to the one in pure oxygen at approximately 200 °C higher temperature. Analyses of the oxidation in ozone show a fast oxidation regime followed by a slow one with activation energies of 0.13±0.01 and 0.19±0.04 eV, respectively. Two regions are also observed for the oxidation in pure O2 with activation energies of 0.20±0.03 eV for the fast oxidation regime and 0.36±0.04 eV for the slow one. X-ray photoelectron spectroscopy results and IR spectral feature frequency shifts suggest that the RTO of silicon in ozone ambient results in a thinner, less-stressed interfacial layer than the one obtained in pure O2. Preliminary electrical characterization using surface charge analyses indicates that the oxides formed in ozone are of superior quality.

  17. Thermal inflation with flaton chemical potential

    NASA Astrophysics Data System (ADS)

    Arai, Masato; Kobayashi, Yoshishige; Okada, Nobuchika; Sasaki, Shin

    2017-04-01

    Thermal inflation driven by a scalar field called a "flaton" is a possible scenario to solve the cosmological moduli problem. We study a model of thermal inflation with a flaton chemical potential. In the presence of the chemical potential, a negative mass squared of the flaton—which is necessary to terminate thermal inflation—is naturally induced. We identify the allowed parameter region for the chemical potential (μ ) and the flaton self-coupling constant to solve the cosmological moduli problem and satisfy theoretical consistencies. In general, the chemical potential is a free parameter and it can be taken to be much larger than the typical scale of soft supersymmetry-breaking parameters of O (1 ) TeV . For μ ≳1 08 GeV , we find that the reheating temperature after thermal inflation can be high enough for the thermal leptogenesis scenario to be operative. This is in sharp contrast to the standard thermal inflation scenario, in which the reheating temperature is quite low and a special mechanism is necessary for generating a sufficient amount of baryon asymmetry in the Universe after thermal inflation.

  18. Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium

    NASA Astrophysics Data System (ADS)

    Massot, Marc; Graille, Benjamin; Magin, Thierry E.

    2011-05-01

    We examine both processes of ionization by electron and heavy-particle impact in spatially uniform plasmas at rest in the absence of external forces. A singular perturbation analysis is used to study the following physical scenario, in which thermal relaxation becomes much slower than chemical reactions. First, electron-impact ionization is investigated. The dynamics of the system rapidly becomes close to a slow dynamics manifold that allows for defining a unique chemical quasi-equilibrium for two-temperature plasmas and proving that the second law of thermodynamics is satisfied. Then, all ionization reactions are taken into account simultaneously, leading to a surprising conclusion: the inner layer for short time scale (or time boundary layer) directly leads to thermal equilibrium. Global thermo-chemical equilibrium is reached within a short time scale, involving only chemical reactions, even if thermal relaxation through elastic collisions is assumed to be slow.

  19. Thermo-chemical dynamics and chemical quasi-equilibrium of plasmas in thermal non-equilibrium

    SciTech Connect

    Massot, Marc; Graille, Benjamin; Magin, Thierry E.

    2011-05-20

    We examine both processes of ionization by electron and heavy-particle impact in spatially uniform plasmas at rest in the absence of external forces. A singular perturbation analysis is used to study the following physical scenario, in which thermal relaxation becomes much slower than chemical reactions. First, electron-impact ionization is investigated. The dynamics of the system rapidly becomes close to a slow dynamics manifold that allows for defining a unique chemical quasi-equilibrium for two-temperature plasmas and proving that the second law of thermodynamics is satisfied. Then, all ionization reactions are taken into account simultaneously, leading to a surprising conclusion: the inner layer for short time scale (or time boundary layer) directly leads to thermal equilibrium. Global thermo-chemical equilibrium is reached within a short time scale, involving only chemical reactions, even if thermal relaxation through elastic collisions is assumed to be slow.

  20. Thermal luminescence spectroscopy chemical imaging sensor.

    PubMed

    Carrieri, Arthur H; Buican, Tudor N; Roese, Erik S; Sutter, James; Samuels, Alan C

    2012-10-01

    The authors present a pseudo-active chemical imaging sensor model embodying irradiative transient heating, temperature nonequilibrium thermal luminescence spectroscopy, differential hyperspectral imaging, and artificial neural network technologies integrated together. We elaborate on various optimizations, simulations, and animations of the integrated sensor design and apply it to the terrestrial chemical contamination problem, where the interstitial contaminant compounds of detection interest (analytes) comprise liquid chemical warfare agents, their various derivative condensed phase compounds, and other material of a life-threatening nature. The sensor must measure and process a dynamic pattern of absorptive-emissive middle infrared molecular signature spectra of subject analytes to perform its chemical imaging and standoff detection functions successfully.

  1. Rapid PCR thermocycling using microscale thermal convection.

    PubMed

    Muddu, Radha; Hassan, Yassin A; Ugaz, Victor M

    2011-03-05

    Many molecular biology assays depend in some way on the polymerase chain reaction (PCR) to amplify an initially dilute target DNA sample to a detectable concentration level. But the design of conventional PCR thermocycling hardware, predominantly based on massive metal heating blocks whose temperature is regulated by thermoelectric heaters, severely limits the achievable reaction speed(1). Considerable electrical power is also required to repeatedly heat and cool the reagent mixture, limiting the ability to deploy these instruments in a portable format. Thermal convection has emerged as a promising alternative thermocycling approach that has the potential to overcome these limitations(2-9). Convective flows are an everyday occurrence in a diverse array of settings ranging from the Earth's atmosphere, oceans, and interior, to decorative and colorful lava lamps. Fluid motion is initiated in the same way in each case: a buoyancy driven instability arises when a confined volume of fluid is subjected to a spatial temperature gradient. These same phenomena offer an attractive way to perform PCR thermocycling. By applying a static temperature gradient across an appropriately designed reactor geometry, a continuous circulatory flow can be established that will repeatedly transport PCR reagents through temperature zones associated with the denaturing, annealing, and extension stages of the reaction (Figure 1). Thermocycling can therefore be actuated in a pseudo-isothermal manner by simply holding two opposing surfaces at fixed temperatures, completely eliminating the need to repeatedly heat and cool the instrument. One of the main challenges facing design of convective thermocyclers is the need to precisely control the spatial velocity and temperature distributions within the reactor to ensure that the reagents sequentially occupy the correct temperature zones for a sufficient period of time(10,11). Here we describe results of our efforts to probe the full 3-D velocity and

  2. Modeling the Thermal Destruction of Chemical Warfare ...

    EPA Pesticide Factsheets

    Symposium Paper In the event of a terrorist attack with chemical warfare agents (CWAs), large quantities of materials, both indoor and outdoor, may be treated with thermal incineration during the site remediation process. This paper reports on a study to examine the thermal decomposition of surrogate CWAs and formation of decomposition by-products bound in model building materials (in this case, ceiling tile) in a pilot-scale rotary kiln incinerator simulator.

  3. Thermal, chemical, and biological processing

    SciTech Connect

    Dale, B.E.; Petersen, G.N.

    1995-12-31

    In the past few years the focus in this area has been changing from the processing of biomass to such issues as downstream processing, product recovery, and integrated process development. It is more and more obvious that commercialization of the various processes for converting biomass to fuels and chemicals will require an integrated approach since each part of the process can profoundly affect all other parts. Although economical production of fuel ethanol remains the major objective in biomass conversion, other large-volume oxychemicals also have great commercial potential. Lactic acid and succinic acid are two such oxychemicals. Separation of these organic acids from the aqueous phase is a particular challenge that is addressed by using membrane and absorption methods.

  4. Earth's interdependent thermal, structural, and chemical evolution

    NASA Astrophysics Data System (ADS)

    Hofmeister, A.; Criss, R. E.

    2012-12-01

    The popular view that 30-55% of Earth's global power is primordial, with deep layers emanating significant power, rests on misunderstandings and models that omit magmatism and outgassing. These processes link Earth's chemical and thermal evolution, while creating layers, mainly because magmas transport latent heat and radioactive isotopes rapidly upwards. We link chemistry to heat flow, measured and theoretical, to understand the interior layering and workings. Quasi-steady state conditions describe most of Earth's history: (1) Accretion was cold and was not a source of deep heat. (2) Friction during core formation cannot have greatly heated the interior (thermodynamics plus buoyancy). (3) Conduction is the governing microscopic mechanism in the deep Earth. (4) Using well-constrained values of thermal conductivity (k), we find that homogeneously distributed radionuclides provide extremely high internal temperature (T) under radial symmetry. Moreover, for any given global power, sequestering heat producing elements into the upper mantle reduces Earth's central temperature by a factor of 10 from a homogeneous distribution. Hence, (5) core formation was a major cooling event. From modern determinations of k(T) we provide a reference conductive geotherm. Present-day global power of 30 TW from heat flux measurements and sequestering of heat producing elements in the upper mantle and transition zone, produces nearly isothermal T = 5300 K below 670 km, which equals experimentally determined freezing of pure Fe0 at the inner core boundary. Core freezing buffers the interior temperatures, while the Sun constrains the surface temperature, providing steady state conditions: Earth's deep interior is isothermal due to these constraints, low flux and high k. Our geotherms point to a stagnant lower mantle and convection above 670 km. Rotational flattening cracks the brittle lithosphere, providing paths for buoyant magmas to ascend. Release of latent heat augments the conductive

  5. Rapid fabrication of ceramic composite tubes using chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Chiang, D.; Besmann, T.M.; Stinton, D.P.; McLaughlin, J.C.; Matlin, W.M.

    1996-06-01

    Ceramic composite tubes can be fabricated with silicon carbide matrix and Nicalon fiber reinforcement using forced flow-thermal gradient chemical vapor infiltration (FCVI). The process model GTCVI is used to design the equipment configuration and to identify conditions for rapid, uniform densification. The initial injector and mandrel design produced radial and longitudinal temperature gradients too large for uniform densification. Improved designs have been evaluated with the model. The most favorable approach utilizes a free-standing preform and an insulated water-cooled gas injector. Selected process conditions are based on the temperature limit of the fiber, matrix stoichiometry and reagent utilization efficiency. Model runs for a tube 12 inches long, 4 inches OD and 1/4 inch wall thickness show uniform densification in approximately 15 hours.

  6. CHEMICAL REACTIVITY TEST: Assessing Thermal Stability and Chemical Compatibility

    SciTech Connect

    Koerner, J; Tran, T; Gagliardi, F; Fontes, A

    2005-04-21

    The thermal stability of high explosive (HE) and its compatibility with other materials are of critical importance in storage and handling practices. These properties are measured at Lawrence Livermore National Laboratory using the chemical reactivity test (CRT). The CRT measures the total amount of gas evolved from a material or combination of materials after being heat treated for a designated period of time. When the test result is compared to a threshold value, the relative thermal stability of an HE or the compatibility of an HE with other materials is determined. We describe the CRT testing apparatus, the experimental procedure, and the comparison methodology and provide examples and discussion of results.

  7. Thermal energy harvesting plasmonic based chemical sensors.

    PubMed

    Karker, Nicholas; Dharmalingam, Gnanaprakash; Carpenter, Michael A

    2014-10-28

    Detection of gases such as H2, CO, and NO2 at 500 °C or greater requires materials with thermal stability and reliability. One of the major barriers toward integration of plasmonic-based chemical sensors is the requirement of multiple components such as light sources and spectrometers. In this work, plasmonic sensing results are presented where thermal energy is harvested using lithographically patterned Au nanorods, replacing the need for an external incident light source. Gas sensing results using the harvested thermal energy are in good agreement with sensing experiments, which used an external incident light source. Principal Component Analysis (PCA) was used to reduce the wavelength parameter space from 665 variables down to 4 variables with similar levels of demonstrated selectivity. The combination of a plasmonic-based energy harvesting sensing paradigm with PCA analysis offers a novel path toward simplification and integration of plasmonic-based sensing methods.

  8. Rapid Thermal Processing (RTP) of semiconductors in space

    NASA Technical Reports Server (NTRS)

    Anderson, T. J.; Jones, K. S.

    1993-01-01

    The progress achieved on the project entitled 'Rapid Thermal Processing of Semiconductors in Space' for a 12 month period of activity ending March 31, 1993 is summarized. The activity of this group is being performed under the direct auspices of the ROMPS program. The main objective of this program is to develop and demonstrate the use of advanced robotics in space with rapid thermal process (RTP) of semiconductors providing the test technology. Rapid thermal processing is an ideal processing step for demonstration purposes since it encompasses many of the characteristics of other processes used in solid state device manufacturing. Furthermore, a low thermal budget is becoming more important in existing manufacturing practice, while a low thermal budget is critical to successful processing in space. A secondary objective of this project is to determine the influence of microgravity on the rapid thermal process for a variety of operating modes. In many instances, this involves one or more fluid phases. The advancement of microgravity processing science is an important ancillary objective.

  9. Impact of ultraviolet light during rapid thermal diffusion

    NASA Astrophysics Data System (ADS)

    Noël, S.; Ventura, L.; Slaoui, A.; Muller, J. C.; Groh, B.; Schindler, R.; Fröschle, B.; Theiler, T.

    1998-05-01

    Rapid thermal processing for junction formation is emerging as a low cost technique for solar cell as well as for other semiconductor device production. Compared to conventional furnace processing, process differences are not only in very high heating and cooling rates, but also in the incoherent emitted radiation spectrum, which can act on dopant diffusion. The photons emitted from tungsten halogen lamps go from far ultraviolet, over visible to infrared light. In this work additional mercury ultraviolet lamps are used during rapid thermal annealing to analyze the influence of high energetic photons on diffusion mechanisms. The diffusion results are discussed in terms of radiation spectrum, involving analysis of diffusion profiles and sheet resistances.

  10. Multidimensional thermal-chemical cookoff modeling

    SciTech Connect

    Baer, M.R.; Gross, R.J.; Gartling, D.K.; Hobbs, M.L.

    1994-08-01

    Multidimensional thermal/chemical modeling is an essential step in the development of a predictive capability for cookoff of energetic materials in systems subjected to abnormal thermal environments. COYOTE II is a state-of-the-art two- and three-dimensional finite element code for the solution of heat conduction problems including surface-to-surface thermal radiation heat transfer and decomposition chemistry. Multistep finite rate chemistry is incorporated into COYOTE II using an operator-splitting methodology; rate equations are solved element-by-element with a modified matrix-free stiff solver, CHEMEQ. COYOTE II is purposely designed with a user-oriented input structure compatible with the database, the pre-processing mesh generation, and the post-processing tools for data visualization shared with other engineering analysis codes available at Sandia National Laboratories. As demonstrated in a companion paper, decomposition during cookoff in a confined or semi-confined system leads to significant mechanical behavior. Although mechanical effect are not presently considered in COYOTE II, the formalism for including mechanics in multidimensions is under development.

  11. Raman scattering from rapid thermally annealed tungsten silicide

    NASA Technical Reports Server (NTRS)

    Kumar, Sandeep; Dasgupta, Samhita; Jackson, Howard E.; Boyd, Joseph T.

    1987-01-01

    Raman scattering as a technique for studying the formation of tungsten silicide is presented. The tungsten silicide films have been formed by rapid thermal annealing of thin tungsten films sputter deposited on silicon substrates. The Raman data are interpreted by using data from resistivity measurements, Auger and Rutherford backscattering measurements, and scanning electron microscopy.

  12. Raman scattering from rapid thermally annealed tungsten silicide

    NASA Technical Reports Server (NTRS)

    Kumar, Sandeep; Dasgupta, Samhita; Jackson, Howard E.; Boyd, Joseph T.

    1987-01-01

    Raman scattering as a technique for studying the formation of tungsten silicide is presented. The tungsten silicide films have been formed by rapid thermal annealing of thin tungsten films sputter deposited on silicon substrates. The Raman data are interpreted by using data from resistivity measurements, Auger and Rutherford backscattering measurements, and scanning electron microscopy.

  13. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    PubMed

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  14. Rapid charging of thermal energy storage materials through plasmonic heating.

    PubMed

    Wang, Zhongyong; Tao, Peng; Liu, Yang; Xu, Hao; Ye, Qinxian; Hu, Hang; Song, Chengyi; Chen, Zhaoping; Shang, Wen; Deng, Tao

    2014-09-01

    Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites.

  15. Rapid Charging of Thermal Energy Storage Materials through Plasmonic Heating

    PubMed Central

    Wang, Zhongyong; Tao, Peng; Liu, Yang; Xu, Hao; Ye, Qinxian; Hu, Hang; Song, Chengyi; Chen, Zhaoping; Shang, Wen; Deng, Tao

    2014-01-01

    Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites. PMID:25175717

  16. Multivariable control of a rapid thermal processor using ultrasonic sensors

    NASA Astrophysics Data System (ADS)

    Dankoski, Paul C. P.

    The semiconductor manufacturing industry faces the need for tighter control of thermal budget and process variations as circuit feature sizes decrease. Strategies to meet this need include supervisory control, run-to-run control, and real-time feedback control. Typically, the level of control chosen depends upon the actuation and sensing available. Rapid Thermal Processing (RTP) is one step of the manufacturing cycle requiring precise temperature control and hence real-time feedback control. At the outset of this research, the primary ingredient lacking from in-situ RTP temperature control was a suitable sensor. This research looks at an alternative to the traditional approach of pyrometry, which is limited by the unknown and possibly time-varying wafer emissivity. The technique is based upon the temperature dependence of the propagation time of an acoustic wave in the wafer. The aim of this thesis is to evaluate the ultrasonic sensors as a potentially viable sensor for control in RTP. To do this, an experimental implementation was developed at the Center for Integrated Systems. Because of the difficulty in applying a known temperature standard in an RTP environment, calibration to absolute temperature is nontrivial. Given reference propagation delays, multivariable model-based feedback control is applied to the system. The modelling and implementation details are described. The control techniques have been applied to a number of research processes including rapid thermal annealing and rapid thermal crystallization of thin silicon films on quartz/glass substrates.

  17. Thermal Emission Light-Curves of Rapidly Rotating Asteroids

    NASA Astrophysics Data System (ADS)

    Rozitis, Ben; Emery, Joshua; Lowry, Stephen; Rozek, Agata; Wolters, Stephen; Snodgrass, Colin; Green, Simon

    2014-12-01

    We propose to use Spitzer/IRAC to obtain simultaneous 3 and 4 um light-curves of 23 rapidly rotating asteroids (rotation periods of less than 3 hrs) to determine thermal inertia and surface roughness spatial variations. These observations will probe asteroid geophysics and constrain the origin of their rapid rotation. Rapidly rotating asteroids are unusual bodies where their own self-gravity is balanced or exceeded by rotational centrifugal forces, and are thought to have acquired their fast rotation rates through the YORP effect - a radiative torque induced by exposure to sunlight. For each target asteroid, we will measure thermal flux in both IRAC bands for a full rotation. When combined with shapes and spin axes derived from our ground-based programme, and a thermophysical model, we will be able to identify any temperature variations resulting from thermal inertia and/or surface roughness variation, and be able to constrain theoretical predictions of YORP rotational acceleration. The thermal property variations will be compared against models of surface gravity in order to provide insights into the physical processes by which asteroids retain and lose surface material. 16 of our target asteroids are being observed at optical wavelengths in a European Southern Observatory (ESO) Large Programme (LP) awarded 82 nights to constrain rotation period changes induced by the YORP effect (PI Stephen Lowry; Program IDs 185.C-1033, 185.C-1034). Approximately 80 additional nights on a range of other facilities has also been awarded for this programme. The ESO LP will support the Spitzer programme by providing shape and spin axis information necessary to search for surface property variations in the thermal emission light-curves of these asteroids. Likewise, the Spitzer/IRAC thermal emission light-curves will allow us to derive the physical properties that drive the YORP effect on the ESO LP asteroids.

  18. Photo, thermal and chemical degradation of riboflavin

    PubMed Central

    Kazi, Sadia Hafeez; Ahmed, Sofia; Anwar, Zubair; Ahmad, Iqbal

    2014-01-01

    Summary Riboflavin (RF), also known as vitamin B2, belongs to the class of water-soluble vitamins and is widely present in a variety of food products. It is sensitive to light and high temperature, and therefore, needs a consideration of these factors for its stability in food products and pharmaceutical preparations. A number of other factors have also been identified that affect the stability of RF. These factors include radiation source, its intensity and wavelength, pH, presence of oxygen, buffer concentration and ionic strength, solvent polarity and viscosity, and use of stabilizers and complexing agents. A detailed review of the literature in this field has been made and all those factors that affect the photo, thermal and chemical degradation of RF have been discussed. RF undergoes degradation through several mechanisms and an understanding of the mode of photo- and thermal degradation of RF may help in the stabilization of the vitamin. A general scheme for the photodegradation of RF is presented. PMID:25246959

  19. Rapid thermal processing of Czochralski silicon substrates: Defects, denuded zones, and minority carrier lifetime

    NASA Technical Reports Server (NTRS)

    Rozgonyi, G. S.; Yang, D. K.; Cao, Y. H.; Radzimski, Z.

    1986-01-01

    Rapid thermal processing (RTP) of Czochralski (Cz) silicon substrates is discussed with its attendant effects on defects, denuded zones, and minority carrier lifetime. Preferential chemical etching and X-ray topography was used to delineate defects which were subsequently correlated with minority carrier lifetime; determined by a pulse metallo-organic decompositon (MOD) test device. The X-ray delineation of grown-in defects was enhanced by a lithium decoration procedure. Results, thus far, show excellent correlation between process-induced defects.

  20. Deep-level transient spectroscopy study of electron traps in rapid thermally annealed SiO 2-capped n-type GaAs layers grown by metalorganic chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Deenapanray, P. N. K.; Lay, M.; Åberg, D.; Tan, H. H.; Svensson, B. G.; Auret, F. D.; Jagadish, C.

    2001-12-01

    Three dominant electron traps S1 ( Ec-0.23 eV), S2* ( Ec-0.53 eV), and S4 ( Ec-0.74 eV) are introduced in SiO 2/n-GaAs after rapid thermal annealing (RTA). A defect S3 ( Ec-0.72 eV) is observed in uncapped and annealed samples only. The S2* arises from the superposition of two defects, of which S2 ( Ec-0.46 eV) can be resolved using filling pulse widths <1 ms. The intensities of S1, S2*, and S4 show Arrhenius-like dependencies on the RTA temperature. We argue that the defects are formed as a result of an increase in the ratio of As : Ga in the near-surface region of the GaAs layers. The electronic and annealing properties of S4 show that it is a member of the EL2 family of defects. The removal of S1 and S2*, as well as the introduction of secondary defects, during isochronal annealing experiments is also discussed.

  1. The Effects of Low-Pressure Rapid Thermal Post-Annealing on the Properties of (Ba, Sr)TiO3 Thin Films Deposited by Liquid Source Misted Chemical Deposition

    NASA Astrophysics Data System (ADS)

    Yang, Ming-Jui; Chien, Chao-Hsin; Leu, Ching-Chich; Zhang, Ren-Jian; Wu, Shich-Chuan; Huang, Tiao-Yuan; Tseng, Tseung-Yuen

    2001-12-01

    The technique of low-pressure post-annealing process with additional second-step annealing for preparation of the Ba0.7Sr0.3TiO3 thin films deposited by liquid source misted chemical deposition (LSMCD) has been proposed. With employing this annealing procedure, the leakage current density can be significantly eliminated by approximately one order of magnitude at 2 V@. In particular, process temperature can be reduced from 650°C to 600°C without suffering deteriorated crystallinity issue, which is identified by both C-V measurement and X-ray diffraction spectrum. The extracted dielectric constant is 310 with extreamly low loss tangent of 0.005. The spectrum of atomic force microscopy (AFM) shows that this low-pressure process results in smoother surface topography. Moreover, thermal desorption spectrums assure that less residual organics and contaminations were left after low pressure post-annealing. This may be one of the reasons for lowering crystallization temperature and the improved electrical properties.

  2. Thermal properties of graphite oxide, thermally reduced graphene and chemically reduced graphene

    NASA Astrophysics Data System (ADS)

    Jankovský, Ondřej; Sedmidubský, David; Lojka, Michal; Sofer, Zdeněk

    2017-07-01

    We compared thermal behavior and other properties of graphite oxide, thermally reduced graphene and chemically reduced graphene. Graphite was oxidized according to the Hofmann method using potassium chlorate as oxidizing agent in strongly acidic environment. In the next step, the formed graphite oxide was chemically or thermally reduced yielding graphene. The mechanism of thermal reduction was studied using STA-MS. Graphite oxide and both thermally and chemically reduced graphenes were analysed by SEM, EDS, elemental combustion analysis, XPS, Raman spectroscopy, XRD and BET. These findings will help for the large scale production of graphene with appropriate chemical composition.

  3. THERMAL AND CHEMICAL EVOLUTION OF COLLAPSING FILAMENTS

    SciTech Connect

    Gray, William J.; Scannapieco, Evan

    2013-05-10

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z Almost-Equal-To 0.1 Z{sub Sun} filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form a dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10{sup -3} Z{sub Sun} filaments, the collapse proceeds much more slowly. This is mostly due to the lower initial temperatures, which lead to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbursting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occurs. We find that we achieve similar accretion rates as NGC 5253 but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  4. Thermal and Chemical Evolution of Collapsing Filaments

    SciTech Connect

    Gray, William J.; Scannapieco, Evan

    2013-01-15

    Intergalactic filaments form the foundation of the cosmic web that connect galaxies together, and provide an important reservoir of gas for galaxy growth and accretion. Here we present very high resolution two-dimensional simulations of the thermal and chemical evolution of such filaments, making use of a 32 species chemistry network that tracks the evolution of key molecules formed from hydrogen, oxygen, and carbon. We study the evolution of filaments over a wide range of parameters including the initial density, initial temperature, strength of the dissociating UV background, and metallicity. In low-redshift, Z ≈ 0.1Z filaments, the evolution is determined completely by the initial cooling time. If this is sufficiently short, the center of the filament always collapses to form dense, cold core containing a substantial fraction of molecules. In high-redshift, Z = 10-3Z filaments, the collapse proceeds much more slowly. This is due mostly to the lower initial temperatures, which leads to a much more modest increase in density before the atomic cooling limit is reached, making subsequent molecular cooling much less efficient. Finally, we study how the gravitational potential from a nearby dwarf galaxy affects the collapse of the filament and compare this to NGC 5253, a nearby starbusting dwarf galaxy thought to be fueled by the accretion of filament gas. In contrast to our fiducial case, a substantial density peak forms at the center of the potential. This peak evolves faster than the rest of the filament due to the increased rate at which chemical species form and cooling occur. We find that we achieve similar accretion rates as NGC 5253, but our two-dimensional simulations do not recover the formation of the giant molecular clouds that are seen in radio observations.

  5. Rapid evolution of thermal tolerance in the water flea Daphnia

    NASA Astrophysics Data System (ADS)

    Geerts, A. N.; Vanoverbeke, J.; Vanschoenwinkel, B.; van Doorslaer, W.; Feuchtmayr, H.; Atkinson, D.; Moss, B.; Davidson, T. A.; Sayer, C. D.; De Meester, L.

    2015-07-01

    Global climate is changing rapidly, and the degree to which natural populations respond genetically to these changes is key to predicting ecological responses. So far, no study has documented evolutionary changes in the thermal tolerance of natural populations as a response to recent temperature increase. Here, we demonstrate genetic change in the capacity of the water flea Daphnia to tolerate higher temperatures using both a selection experiment and the reconstruction of evolution over a period of forty years derived from a layered dormant egg bank. We observed a genetic increase in thermal tolerance in response to a two-year ambient +4 °C selection treatment and in the genotypes of natural populations from the 1960s and 2000s hatched from lake sediments. This demonstrates that natural populations have evolved increased tolerance to higher temperatures, probably associated with the increased frequency of heat waves over the past decades, and possess the capacity to evolve increased tolerance to future warming.

  6. Effect of Rapid Thermal Cooling on Mechanical Rock Properties

    NASA Astrophysics Data System (ADS)

    Kim, Kwangmin; Kemeny, John; Nickerson, Mark

    2014-11-01

    Laboratory tests have been conducted to investigate the effects of rapid thermal cooling on various rock specimens including igneous, sedimentary, and metamorphic rocks. At first, various types of thermal loading were conducted: heating up to 100, 200, and 300 °C, followed by rapid cooling with a fan. In addition, multiple cyclic thermal cooling (10, 15 and 20 cycles) with a maximum temperature of only 100 °C was conducted. Experiments included edge notched disc (END) tests to determine the Mode I fracture toughness, Brazilian disc tests to determine tensile strength, seismic tests to determine P-wave velocity, and porosity tests leading to meaningful results. Even though only small changes of temperature (rapid cooling from 100 °C to room temperature) were applied, the results showed that crack growth occurred in some rock types (granite, diabase with ore veins, and KVS) while crack healing occurred in other rock types (diabase without ore veins, quartzite, and skarn). To better understand the results, 3D transient thermo-mechanical analysis was conducted using the ANSYS program. The results indicated that there was a thin region near the outside of the specimen where large tensile stresses occur and microcracking would be expected, and that there was a large area in the middle of the specimen where lower magnitude compressive stresses occur and crack closure would be expected. It was found that the more heterogeneous and more coarse-grained rock types are more likely to exhibit crack growth, while less heterogeneous and more fine-grained rocks are more likely to exhibit crack healing.

  7. Adaptive process control for a rapid thermal processor

    NASA Astrophysics Data System (ADS)

    Dilhac, Jean-Marie R.; Ganibal, Christian; Bordeneuve, J.; Dahhou, B.; Amat, L.; Picard, Antoni

    1991-04-01

    PD (Proportional Integrated Derivative) controllers applied to temperature regulation in a rapid thermal processor are first presented. The setting method of the control parameters together with the corresponding experimental results is given. Evidence in favour of parameter dynamic adjustment is demonstrated. A new algorithm based upon parameter scheduling and providing enlarged control capability is then presented and tested with various wafers and processors. At last insights about closed loop self-tuning using Generalized Predictive Control algorithm are given and the corresponding results discussed. 1.

  8. Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

    SciTech Connect

    Zhou, Lan; Suram, Santosh K.; Becerra-Stasiewicz, Natalie; Mitrovic, Slobodan; Kan, Kevin; Jones, Ryan J. R.; Gregoire, John M.

    2015-05-27

    Recent efforts have demonstrated enhanced tailoring of material functionality with mixed-anion materials, yet exploratory research with mixed-anion chemistries is limited by the sensitivity of these materials to synthesis conditions. In order to synthesize a particular metal oxynitride compound by traditional reactive annealing we require specific, limited ranges of both oxygen and nitrogen chemical potentials in order to establish equilibrium between the solid-state material and a reactive atmosphere. While using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing for synthesis of mixed-anion inorganic materials. Heuristic optimization of reactive gas pressures to attain a desired anion stoichiometry is discussed, and the ability of rapid thermal processing to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide and oxynitride phases.

  9. Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

    DOE PAGES

    Zhou, Lan; Suram, Santosh K.; Becerra-Stasiewicz, Natalie; ...

    2015-05-27

    Recent efforts have demonstrated enhanced tailoring of material functionality with mixed-anion materials, yet exploratory research with mixed-anion chemistries is limited by the sensitivity of these materials to synthesis conditions. In order to synthesize a particular metal oxynitride compound by traditional reactive annealing we require specific, limited ranges of both oxygen and nitrogen chemical potentials in order to establish equilibrium between the solid-state material and a reactive atmosphere. While using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing for synthesis of mixed-anion inorganic materials. Heuristic optimization of reactive gas pressures to attainmore » a desired anion stoichiometry is discussed, and the ability of rapid thermal processing to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide and oxynitride phases.« less

  10. Deposition, patterning, and utility of conductive materials for the rapid prototyping of chemical and bioanalytical devices.

    PubMed

    Gabardo, C M; Soleymani, L

    2016-06-21

    Rapid prototyping is a critical step in the product development cycle of miniaturized chemical and bioanalytical devices, often categorized as lab-on-a-chip devices, biosensors, and micro-total analysis systems. While high throughput manufacturing methods are often preferred for large-volume production, rapid prototyping is necessary for demonstrating and predicting the performance of a device and performing field testing and validation before translating a product from research and development to large volume production. Choosing a specific rapid prototyping method involves considering device design requirements in terms of minimum feature sizes, mechanical stability, thermal and chemical resistance, and optical and electrical properties. A rapid prototyping method is then selected by making engineering trade-off decisions between the suitability of the method in meeting the design specifications and manufacturing metrics such as speed, cost, precision, and potential for scale up. In this review article, we review four categories of rapid prototyping methods that are applicable to developing miniaturized bioanalytical devices, single step, mask and deposit, mask and etch, and mask-free assembly, and we will focus on the trade-offs that need to be made when selecting a particular rapid prototyping method. The focus of the review article will be on the development of systems having a specific arrangement of conductive or semiconductive materials.

  11. Thermal Conductivity of Gas Mixtures in Chemical Equilibrium

    NASA Technical Reports Server (NTRS)

    Brokaw, Richard S.

    1960-01-01

    The expression for the thermal conductivity of gas mixtures in chemical equilibrium is presented in a simpler and less restrictive form. This new form is shown to be equivalent to the previous equations.

  12. Combustion chemical vapor desposited coatings for thermal barrier coating systems

    SciTech Connect

    Hampikian, J.M.; Carter, W.B.

    1995-10-01

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings.

  13. Chemical, thermal and mechanical stabilities of metal-organic frameworks

    NASA Astrophysics Data System (ADS)

    Howarth, Ashlee J.; Liu, Yangyang; Li, Peng; Li, Zhanyong; Wang, Timothy C.; Hupp, Joseph T.; Farha, Omar K.

    2016-03-01

    The construction of thousands of well-defined, porous, metal-organic framework (MOF) structures, spanning a broad range of topologies and an even broader range of pore sizes and chemical functionalities, has fuelled the exploration of many applications. Accompanying this applied focus has been a recognition of the need to engender MOFs with mechanical, thermal and/or chemical stability. Chemical stability in acidic, basic and neutral aqueous solutions is important. Advances over recent years have made it possible to design MOFs that possess different combinations of mechanical, thermal and chemical stability. Here, we review these advances and the associated design principles and synthesis strategies. We focus on how these advances may render MOFs effective as heterogeneous catalysts, both in chemically harsh condensed phases and in thermally challenging conditions relevant to gas-phase reactions. Finally, we briefly discuss future directions of study for the production of highly stable MOFs.

  14. Pore Size Control of Ultra-thin Silicon Membranes by Rapid Thermal Carbonization

    PubMed Central

    Fang, David Z.; Striemer, Christopher C.; Gaborski, Thomas R.; McGrath, James L.; Fauchet, Philippe M.

    2010-01-01

    Rapid thermal carbonization in a dilute acetylene (C2H2) atmosphere has been used to chemically modify and precisely tune the pore size of ultrathin porous nanocrystalline silicon (pnc-Si). The magnitude of size reduction was controlled by varying the process temperature and time. Under certain conditions, the carbon coating displayed atomic ordering indicative of graphene layer formation conformal to the pore walls. Initial experiments show that carbonized membranes follow theoretical predictions for hydraulic permeability and retain the precise separation capabilities of untreated membranes. PMID:20839831

  15. Rapid thermal annealing of indium phosphide compound semiconductors

    NASA Technical Reports Server (NTRS)

    Biedenbender, Michael D.; Kapoor, Vik J.; Williams, W. D.

    1987-01-01

    The rapid thermal annealing (RTA) of indium phosphide (InP) substrates using a proximity contact method and silicon nitride encapsulation is investigated. The surface conditions of the InP substrates following cleaning with procedures A and B are analyzed. Procedure A involves using an iodic acid solution to remove work-damage InP surface layers and B is a degasssing process and hydrofluoric acid solution for native oxide removal. AES, XPS, and SIMS data of the proximity contact and silicon nitride encapsulated annealed samples are examined. The data reveal that RTA using proximity contact with silicon wafers does not provide adequate protection; however, the InP sample is successfully annealed when protected by a silicon nitride encapsulant.

  16. Liquid hydrogen turbopump rapid start program. [thermal preconditioning using coatings

    NASA Technical Reports Server (NTRS)

    Wong, G. S.

    1973-01-01

    This program was to analyze, test, and evaluate methods of achieving rapid-start of a liquid hydrogen feed system (inlet duct and turbopump) using a minimum of thermal preconditioning time and propellant. The program was divided into four tasks. Task 1 includes analytical studies of the testing conducted in the other three tasks. Task 2 describes the results from laboratory testing of coating samples and the successful adherence of a KX-635 coating to the internal surfaces of the feed system tested in Task 4. Task 3 presents results of testing an uncoated feed system. Tank pressure was varied to determine the effect of flowrate on preconditioning. The discharge volume and the discharge pressure which initiates opening of the discharge valve were varied to determine the effect on deadhead (no through-flow) start transients. Task 4 describes results of testing a similar, internally coated feed system and illustrates the savings in preconditioning time and propellant resulting from the coatings.

  17. Rapid identification of chemical genetic interactions in Saccharomyces cerevisiae.

    PubMed

    Dilworth, David; Nelson, Christopher J

    2015-04-05

    Determining the mode of action of bioactive chemicals is of interest to a broad range of academic, pharmaceutical, and industrial scientists. Saccharomyces cerevisiae, or budding yeast, is a model eukaryote for which a complete collection of ~6,000 gene deletion mutants and hypomorphic essential gene mutants are commercially available. These collections of mutants can be used to systematically detect chemical-gene interactions, i.e. genes necessary to tolerate a chemical. This information, in turn, reports on the likely mode of action of the compound. Here we describe a protocol for the rapid identification of chemical-genetic interactions in budding yeast. We demonstrate the method using the chemotherapeutic agent 5-fluorouracil (5-FU), which has a well-defined mechanism of action. Our results show that the nuclear TRAMP RNA exosome and DNA repair enzymes are needed for proliferation in the presence of 5-FU, which is consistent with previous microarray based bar-coding chemical genetic approaches and the knowledge that 5-FU adversely affects both RNA and DNA metabolism. The required validation protocols of these high-throughput screens are also described.

  18. Rapid Identification of Chemical Genetic Interactions in Saccharomyces cerevisiae

    PubMed Central

    Dilworth, David; Nelson, Christopher J.

    2015-01-01

    Determining the mode of action of bioactive chemicals is of interest to a broad range of academic, pharmaceutical, and industrial scientists. Saccharomyces cerevisiae, or budding yeast, is a model eukaryote for which a complete collection of ~6,000 gene deletion mutants and hypomorphic essential gene mutants are commercially available. These collections of mutants can be used to systematically detect chemical-gene interactions, i.e. genes necessary to tolerate a chemical. This information, in turn, reports on the likely mode of action of the compound. Here we describe a protocol for the rapid identification of chemical-genetic interactions in budding yeast. We demonstrate the method using the chemotherapeutic agent 5-fluorouracil (5-FU), which has a well-defined mechanism of action. Our results show that the nuclear TRAMP RNA exosome and DNA repair enzymes are needed for proliferation in the presence of 5-FU, which is consistent with previous microarray based bar-coding chemical genetic approaches and the knowledge that 5-FU adversely affects both RNA and DNA metabolism. The required validation protocols of these high-throughput screens are also described. PMID:25867090

  19. Characterizing thermal sweeping: a rapid disc dispersal mechanism

    NASA Astrophysics Data System (ADS)

    Owen, James E.; Hudoba de Badyn, Mathias; Clarke, Cathie J.; Robins, Luke

    2013-12-01

    We consider the properties of protoplanetary discs that are undergoing inside-out clearing by photoevaporation. In particular, we aim to characterize the conditions under which a protoplanetary disc may undergo `thermal sweeping', a rapid (≲104 years) disc destruction mechanism proposed to occur when a clearing disc reaches sufficiently low surface density at its inner edge and where the disc is unstable to runaway penetration by the X-rays. We use a large suite of 1D radiation-hydrodynamic simulations to probe the observable parameter space, which is unfeasible in higher dimensions. These models allow us to determine the surface density at which thermal sweeping will take over the disc's evolution and to evaluate this critical surface density as a function of X-ray luminosity, stellar mass and inner hole radius. We find that this critical surface density scales linearly with X-ray luminosity, increases with inner hole radius and decreases with stellar mass, and we develop an analytic model that reproduces these results. This surface density criterion is then used to determine the evolutionary state of protoplanetary discs at the point that they become unstable to destruction by thermal sweeping. We find that transition discs created by photoevaporation will undergo thermal sweeping when their inner holes reach 20-40 au, implying that transition discs with large holes and no accretion (which were previously a predicted outcome of the later stages of all flavours of the photoevaporation model) will not form. Thermal sweeping thus avoids the production of large numbers of large, non-accreting holes (which are not observed) and implies that the majority of holes created by photoevaporation should still be accreting. We emphasize that the surface density criteria that we have developed apply to all situations where the disc develops an inner hole that is optically thin to X-rays. It thus applies not only to the case of holes originally created by photoevaporation but

  20. Rapid evolution of metabolic traits explains thermal adaptation in phytoplankton.

    PubMed

    Padfield, Daniel; Yvon-Durocher, Genevieve; Buckling, Angus; Jennings, Simon; Yvon-Durocher, Gabriel

    2015-11-26

    Understanding the mechanisms that determine how phytoplankton adapt to warming will substantially improve the realism of models describing ecological and biogeochemical effects of climate change. Here, we quantify the evolution of elevated thermal tolerance in the phytoplankton, Chlorella vulgaris. Initially, population growth was limited at higher temperatures because respiration was more sensitive to temperature than photosynthesis meaning less carbon was available for growth. Tolerance to high temperature evolved after ≈ 100 generations via greater down-regulation of respiration relative to photosynthesis. By down-regulating respiration, phytoplankton overcame the metabolic constraint imposed by the greater temperature sensitivity of respiration and more efficiently allocated fixed carbon to growth. Rapid evolution of carbon-use efficiency provides a potentially general mechanism for thermal adaptation in phytoplankton and implies that evolutionary responses in phytoplankton will modify biogeochemical cycles and hence food web structure and function under warming. Models of climate futures that ignore adaptation would usefully be revisited. © 2015 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  1. Lunar Reconnaissance Orbiter (LRO) Rapid Thermal Design Development

    NASA Technical Reports Server (NTRS)

    Baker, Charles; Cottingham, Christine; Garrison, Matthew; Melak, Tony; Peabody, Sharon; Powers, Dan

    2009-01-01

    The Lunar Reconnaissance Orbiter (LRO) project had a rapid development schedule starting with project conception in spring of 2004, instrument and launch vehicle selection late in 2005 and then launch in early 2009. The lunar thermal environment is one of the harshest in our solar system with the heavy infrared loading of the moon due to low albedo, lack of lunar atmosphere, and low effective regolith conduction. This set of constraints required a thermal design which maximized performance (minimized radiator area and cold control heater power) and minimized thermal hardware build at the orbiter level (blanketing, and heater service). The orbiter design located most of the avionics on an isothermalized heat pipe panel called the IsoThermal Panel (ITP). The ITP was coupled by dual bore heat pipes to an Optical Solar Reflector (OSR) covered heat pipe radiator. By coupling all of the avionics to one system, the hardware was simplified. The seven instruments were mainly heritage instruments which resulted in their desired radiators being located by their heritage design. This minimized instrument redesigns and therefore allowed them to be delivered earlier, though it resulted in a more complex orbiter level blanket and heater service design. Three of the instruments were mounted on a tight pointing M55J optical bench that needed to be covered in heaters to maintain pointing. Two were mounted to spacecraft controlled radiators. One was mounted to the ITP Dual Bores. The last was mounted directly to the bus structure on the moon facing panel. The propulsion system utilized four-20 pound insertion thrusters and eight-5 pound attitude control thrusters (ACS) in addition to 1000 kg of fuel in two large tanks. The propulsion system had a heater cylinder and a heated mounting deck for the insertion thrusters which coupled most of the propulsion design together simplifying the heater design. The High Gain Antenna System (HGAS) and Solar Array System (SAS) used dual axis

  2. A fully coupled thermal, chemical, mechanical cookoff model

    SciTech Connect

    Hobbs, M.L.; Baer, M.R.; Gross, R.J.

    1994-05-01

    Cookoff modeling of confined energetic materials involves the coupling of thermal, chemical and mechanical effects. In the past, modeling has focussed on the prediction of thermal runaway with little regard to the effects of mechanical behavior of the energetic material. To address the mechanical response of the energetic material, a constitutive submodel has been developed which can be incorporated into thermal-chemical-mechanical analysis. This work presents development of this submodel and its incorporation into a fully coupled one-dimensional, thermal-chemical-mechanical computer code to simulate thermal initiation of energetic materials. Model predictions include temperature, chemical species, stress, strain, solid/gas pressure, solid/gas density, yield function, and gas volume fraction. Sample results from a scaled aluminum tube filled with RDX exposed to a constant temperature bath at 500 K will be displayed. The micromechanical submodel is based on bubble mechanics which describes nucleation, decomposition, and elastic/plastic mechanical behavior. This constitutive material description requires input of temperatures and reacted fraction of the energetic material as provided by the reactive heat flow code, XCHEM, and the mechanical response is predicted using a quasistatic mechanics code, SANTOS. A parametric sensitivity analysis indicates that a small degree of decomposition causes significant pressurization of the energetic material, which implies that cookoff modeling must consider the strong interaction between thermal-chemistry and mechanics. This document consists of view graphs from the poster session.

  3. Comparison of chemical and heating methods to enhance latent fingerprint deposits on thermal paper.

    PubMed

    Bond, John W

    2014-03-01

    A comparison is made of proprietary methods to develop latent fingerprint deposits on the inked side of thermal paper using either chemical treatment (Thermanin) or the application of heat to the paper (Hot Print System). Results with a trial of five donors show that the application of heat produces statistically significantly more fingerprint ridge detail than the chemical treatment for both fingerprint deposits aged up to 4 weeks and for a nine sequence depletion series. Subjecting the thermal paper to heat treatment with the Hot Print System did not inhibit subsequent ninhydrin chemical development of fingerprint deposits on the noninked side of the paper. A further benefit of the application of heat is the rapid development of fingerprint deposits (less than a minute) compared with up to 12 h for the Thermanin chemical treatment.

  4. Chemical enhancement of fingermark in blood on thermal paper.

    PubMed

    Hong, Sungwook; Seo, Jin Yi

    2015-12-01

    Chemical enhancement methods for fingermark in blood deposited on the surface of a thermal paper substrate were examined. The blood-sensitive reagents compared were LCV (leuco crystal violet), Amido black and Hungarian red. Fingermark in blood on the surface of thermal paper can be fixed with 2% 5-sulfosalicylic acid solution. LCV was found as an inadequate blood staining reagent because of bubbling, diffusion, and blurring on the surface of thermal paper. Hungarian red was also an inadequate blood staining reagent because excess Hungarian red on the surface of thermal paper was not washed away in the de-staining procedure. Amido black was the best staining reagent among three staining reagents compared. The maximum dilution ratio visible to the naked eye after Amido black staining was 1 in 80 for the thermally sensitive surface and 1 in 20 for the thermally non-sensitive surface.

  5. Thermal and chemical effects of turkey feathers pyrolysis.

    PubMed

    Kluska, Jacek; Kardaś, Dariusz; Heda, Łukasz; Szumowski, Mateusz; Szuszkiewicz, Jarosław

    2016-03-01

    This study examines the thermal and chemical effects of the pyrolysis of turkey feathers. Research of feathers pyrolysis is important because of their increasing production and difficulties of their utilization. The experiments were carried out by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and two pyrolytic reactors. The experimental investigation indicated that the feather material liquefies at temperatures between 210 and 240°C. This liquefaction together with the agglomeration of various dispersed and porous elements of the feathers into larger droplets leads to the volume reduction. Moreover, this work presents characteristics of the composition of the solid, liquid and gaseous products of turkey feathers pyrolysis at different temperatures. The higher heating value (HHV) of gaseous products in temperature 900°C equals 19.28 MJ/Nm(3) making the gases suitable for use as a fuel. The thermochemical conversion of turkey feathers leads to the formation of poisonous compounds such as hydrogen cyanide (HCN) in the liquid (0.13%) and gaseous (88 mg/Nm(3)) products. The phenomenon of liquefaction of feathers is important because it can lead to rapid degradation of the walls of reactors, and the formation of deposits.

  6. On-line DNA analysis system with rapid thermal cycling

    DOEpatents

    Swerdlow, H.P.; Wittwer, C.T.

    1999-08-10

    This application describes an apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column. 6 figs.

  7. On-line DNA analysis system with rapid thermal cycling

    DOEpatents

    Swerdlow, Harold P.; Wittwer, Carl T.

    1999-01-01

    An apparatus particularly suited for subjecting biological samples to any necessary sample preparation tasks, subjecting the sample to rapid thermal cycling, and then subjecting the sample to subsequent on-line analysis using one or more of a number of analytical techniques. The apparatus includes a chromatography device including an injection means, a chromatography pump, and a chromatography column. In addition, the apparatus also contains a capillary electrophoresis device consisting of a capillary electrophoresis column with an inlet and outlet end, a means of injection, and means of applying a high voltage to cause the differential migration of species of interest through the capillary column. Effluent from the liquid chromatography column passes over the inlet end of the capillary electrophoresis column through a tee structure and when the loading of the capillary electrophoresis column is desired, a voltage supply is activated at a precise voltage and polarity over a specific duration to cause sample species to be diverted from the flowing stream to the capillary electrophoresis column. A laser induced fluorescence detector preferably is used to analyze the products separated while in the electrophoresis column.

  8. Coupled thermal/chemical/mechanical modeling of insensitive explosives in thermal environments

    SciTech Connect

    Nichols, A.L. III

    1996-05-01

    The ability to predict the response of a weapon system that contains insensitive explosives to elevated temperatures is important in understanding its safety characteristics. To model such a system at elevated temperatures in a finite element computer code requires a variety of capabilities. These modeling capabilities include thermal diffusion and convection to transport the heat to the explosives in the weapon system, temperature based chemical reaction modeling of the decomposition of the explosive materials, and mechanical modeling of both the metal casing and the unreacted and decomposed explosive. The Chemical TOPAZ code has been developed to model coupled thermal/chemical problems where we do not need to model the mass motion. We have also developed the LYNX2D code, based on PALM2D and Chemical TOPAZ, which is an implicit, two-dimensional coupled thermal/chemical/mechanical finite element model computer code. Some representative examples are shown. {copyright} {ital 1996 American Institute of Physics.}

  9. Amniotic membrane transplantation for acute chemical or thermal burns.

    PubMed

    Meller, D; Pires, R T; Mack, R J; Figueiredo, F; Heiligenhaus, A; Park, W C; Prabhasawat, P; John, T; McLeod, S D; Steuhl, K P; Tseng, S C

    2000-05-01

    To determine whether preserved human amniotic membrane (AM) can be used to treat ocular burns in the acute stage. Prospective, noncomparative, interventional case series. Thirteen eyes from 11 patients with acute burns, 10 eyes with chemical burns and 3 with thermal burns of grades II-III (7 eyes) and grade IV (6 eyes), treated at 7 different facilities. Patients received amniotic membrane transplantation (AMT) within 2 weeks after the injury. Integrity of ocular surface epithelium and visual acuity during 9 months of follow-up. Ten patients were male and one patient was female; most were young (38.2 +/- 10.6 years). For a follow-up of 8.8 + 4.7 months, 11 of 13 eyes (84.63%) showed epithelialization within 2 to 5 weeks (23.7 +/- 9.8 days), and final visual acuity improved > or = 6 lines (6 eyes), 4 to 5 lines (2 eyes), and 1 to 3 lines (2 eyes); only one eye experienced a symblepharon. Eyes with burns of grade II to III showed more visual improvement (7.3 +/- 3 lines) than those with burns of grade IV (2.3 +/- 3.0 lines; P < 0.05, unpaired t test). In the group with grade II or III burns, none had limbal stem cell deficiency. All eyes in the group with grade IV burns did experience limbal stem cell deficiency. Amniotic membrane transplantation is effective in promoting re-epithelialization and reducing inflammation, thus preventing scarring sequelae in the late stage. In mild to moderate burns, AMT alone rapidly restores both corneal and conjunctival surfaces. In severe burns, however, it restores the conjunctival ocular surface without debilitating symblepharon and reduces limbal stromal inflammation, but does not prevent limbal stem cell deficiency, which requires further limbal stem cell transplantation. These results underscore the importance of immediate intervention in the acute stage of eyes with severely damaged ocular surface. Further prospective randomized studies including a control group are required to determine the effectiveness of AMT in acute

  10. Microwave-assisted specific chemical digestion for rapid protein identification.

    PubMed

    Hua, Lin; Low, Teck Yew; Sze, Siu Kwan

    2006-01-01

    We have developed a rapid microwave-assisted protein digestion technique based on classic acid hydrolysis reaction with 2% formic acid solution. In this mild chemical environment, proteins are hydrolyzed to peptides, which can be directly analyzed by MALDI-MS or ESI-MS without prior sample purification. Dilute formic acid cleaves proteins specifically at the C-terminal of aspartyl (Asp) residues within 10 min of exposure to microwave irradiation. By adjusting the irradiation time, we found that the extent of protein fragmentation can be controlled, as shown by the single fragmentation of myoglobin at the C-terminal of any of the Asp residues. The efficacy and simplicity of this technique for protein identification are demonstrated by the peptide mass maps of in-gel digested myoglobin and BSA, as well as proteins isolated from Escherichia coli K12 cells.

  11. A quantum chemical method for rapid optimization of protein structures.

    PubMed

    Wada, Mitsuhito; Sakurai, Minoru

    2005-01-30

    A quantum chemical method for rapid optimization of protein structures is proposed. In this method, a protein structure is treated as an assembly of amino acid units, and the geometry optimization of each unit is performed with taking the effect of its surrounding environment into account. The optimized geometry of a whole protein is obtained by repeated application of such a local optimization procedure over the entire part of the protein. Here, we implemented this method in the MOPAC program and performed geometry optimization for three different sizes of proteins. Consequently, these results demonstrate that the total energies of the proteins are much efficiently minimized compared with the use of conventional optimization methods, including the MOZYME algorithm (a representative linear-scaling method) with the BFGS routine. The proposed method is superior to the conventional methods in both CPU time and memory requirements.

  12. Combustion chemical vapor deposited coatings for thermal barrier coating systems

    SciTech Connect

    Hampikian, J.M.; Carter, W.B.

    1995-12-31

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings. In this report, the evaluation of alumina and ceria coatings on a nickel-chromium alloy is described.

  13. Tracking thermal fronts with temperature-sensitive, chemically reactive tracers

    SciTech Connect

    Robinson, B.A.; Birdsell, S.A.

    1987-01-01

    Los Alamos is developing tracer techniques using reactive chemicals to track thermal fronts in fractured geothermal reservoirs. If a nonadsorbing tracer flowing from the injection to production well chemically reacts, its reaction rate will be a strong function of temperature. Thus the extent of chemical reaction will be greatest early in the lifetime of the system, and less as the thermal front progresses from the injection to production well. Early laboratory experiments identified tracers with chemical kinetics suitable for reservoirs in the temperature range of 75 to 100/sup 0/C. Recent kinetics studies have focused on the kinetics of hydrolysis of derivatives of bromobenzene. This class of reactions can be used in reservoirs ranging in temperature from 150 to 275/sup 0/C, which is of greater interest to the geothermal industry. Future studies will include laboratory adsorption experiments to identify possibly unwanted adsorption on granite, development of sensitive analytical techniques, and a field demonstration of the reactive tracer concept.

  14. Rapid Chemical Vapor Detection Using Optofluidic Ring Resonators

    NASA Astrophysics Data System (ADS)

    Sun, Yuze; Shopova, Siyka I.; White, Ian M.; Frye-Mason, Greg; Fan, Xudong

    The optofluidic ring resonator (OFRR) is a novel gas sensing technology platform. In an OFRR gas sensor, the OFRR interior surface is coated with a layer of vapor-sensitive polymer. The interaction between the polymer and the gas molecules flowing through the OFRR results in a change in polymer refractive index and thickness, which can be detected by the circulating waveguide modes supported by the circular cross section of the OFRR. Due to the excellent fluidics of a capillary, the OFRR is capable of detecting chemical vapors rapidly with very low sample volume. In addition, the OFRR is highly compatible with gas chromatography (GC) and is a promising platform for development of micro-GC (μGC) with unique multipoint, on-column detection capability. In this chapter, we will discuss the fundamental operational principles of the OFRR gas sensor, followed by examples of rapid detection of several representative vapor analytes. The development of an OFRR-based μGC system and its applications in explosive separation and detection will also be presented.

  15. Modeling of Tungsten Thermal Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Kim, Byunghoon; Akiyama, Yasunobu; Imaishi, Nobuyuki; Park, Heung-Chul

    1999-05-01

    Low-pressure chemical vapor deposition (LPCVD) of tungsten (W)film on silicon (Si) substrate was performed by reducting hexafluoride(WF6) with hydrogen. This CVD system is known for its nonlineardependence of growth rate on WF6 concentration. This study adopted asimple surface-reaction model which assumes that the precursor, i.e.,WF6, in the gas phase adsorbs on solid surfaces and then the adsorbedWF6 molecule is converted into tungsten solid film. The two kineticparameters involved in the model are derived from the experimentalresults. The solidification rate constant (ks) is equal to the growthrate at very high WF6 concentrations. The adsorption rate constant(ka) is derived from profile analyses of films grown in microtrenchesunder very low WF6 concentrations by applying the conventional MonteCarlo simulation code, which is valid for linear surface-reactionsystems. In the temperature range of 623 to 823 K, ka and ks haveactivation energies of 82 kJmol-1, 66.1 kJmol-1, respectively. A newlyproposed Monte Carlo simulation for nonlinear reaction systems, incombination with the two kinetic parameters, can quantitativelypredict the shape of film in microtrenches for a wide range oftemperatures and WF6 concentrations.

  16. Engineered Barrier Systems Thermal-Hydraulic-Chemical Column Test Report

    SciTech Connect

    W.E. Lowry

    2001-12-13

    The Engineered Barrier System (EBS) Thermal-Hydraulic-Chemical (THC) Column Tests provide data needed for model validation. The EBS Degradation, Flow, and Transport Process Modeling Report (PMR) will be based on supporting models for in-drift THC coupled processes, and the in-drift physical and chemical environment. These models describe the complex chemical interaction of EBS materials, including granular materials, with the thermal and hydrologic conditions that will be present in the repository emplacement drifts. Of particular interest are the coupled processes that result in mineral and salt dissolution/precipitation in the EBS environment. Test data are needed for thermal, hydrologic, and geochemical model validation and to support selection of introduced materials (CRWMS M&O 1999c). These column tests evaluated granular crushed tuff as potential invert ballast or backfill material, under accelerated thermal and hydrologic environments. The objectives of the THC column testing are to: (1) Characterize THC coupled processes that could affect performance of EBS components, particularly the magnitude of permeability reduction (increases or decreases), the nature of minerals produced, and chemical fractionation (i.e., concentrative separation of salts and minerals due to boiling-point elevation). (2) Generate data for validating THC predictive models that will support the EBS Degradation, Flow, and Transport PMR, Rev. 01.

  17. Fuels and chemicals from biomass using solar thermal energy

    NASA Technical Reports Server (NTRS)

    Giori, G.; Leitheiser, R.; Wayman, M.

    1981-01-01

    The significant nearer term opportunities for the application of solar thermal energy to the manufacture of fuels and chemicals from biomass are summarized, with some comments on resource availability, market potential and economics. Consideration is given to the production of furfural from agricultural residues, and the role of furfural and its derivatives as a replacement for petrochemicals in the plastics industry.

  18. Chemical Changes in Carbohydrates Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Hoseney, R. Carl

    1984-01-01

    Discusses chemical changes that occur in the carbohydrates found in food products when these products are subjected to thermal processing. Topics considered include browning reactions, starch found in food systems, hydrolysis of carbohydrates, extrusion cooking, processing of cookies and candies, and alterations in gums. (JN)

  19. Chemical Changes in Carbohydrates Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Hoseney, R. Carl

    1984-01-01

    Discusses chemical changes that occur in the carbohydrates found in food products when these products are subjected to thermal processing. Topics considered include browning reactions, starch found in food systems, hydrolysis of carbohydrates, extrusion cooking, processing of cookies and candies, and alterations in gums. (JN)

  20. Fuels and chemicals from biomass using solar thermal energy

    NASA Astrophysics Data System (ADS)

    Giori, G.; Leitheiser, R.; Wayman, M.

    1981-05-01

    The significant nearer term opportunities for the application of solar thermal energy to the manufacture of fuels and chemicals from biomass are summarized, with some comments on resource availability, market potential and economics. Consideration is given to the production of furfural from agricultural residues, and the role of furfural and its derivatives as a replacement for petrochemicals in the plastics industry.

  1. Chemical Changes in Lipids Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Nawar, Wassef W.

    1984-01-01

    Describes heat effects on lipids, indicating that the chemical and physical changes that occur depend on the lipid's composition and conditions of treatment. Thermolytic and oxidation reactions, thermal/oxidative interaction of lipids with other food components and the chemistry of frying are considered. (JN)

  2. Chemical Changes in Lipids Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Nawar, Wassef W.

    1984-01-01

    Describes heat effects on lipids, indicating that the chemical and physical changes that occur depend on the lipid's composition and conditions of treatment. Thermolytic and oxidation reactions, thermal/oxidative interaction of lipids with other food components and the chemistry of frying are considered. (JN)

  3. Suspended heated silicon platform for rapid thermal control of surface reactions with application to carbon nanotube synthesis.

    PubMed

    van Laake, Lucas; Hart, Anastasios John; Slocum, Alexander H

    2007-08-01

    Rapid continuous thermal control of chemical reactions such as those for chemical vapor deposition (CVD) growth of nanotubes and nanowires cannot be studied using traditional reactors such as tube furnaces, which have large thermal masses. We present the design, modeling, and verification of a simple, low-cost reactor based on resistive heating of a suspended silicon platform. This system achieves slew rates exceeding 100 degrees C/s, enabling studies of rapid heating and thermal cycling. Moreover, the reaction surface is available for optical monitoring. A first-generation CVD apparatus encapsulates the heated silicon platform inside a sealed quartz tube, and initial experiments demonstrate growth of films of tangled single-wall and aligned multiwall carbon nanotubes using this system. The reactor can be straightforwardly scaled to larger or smaller substrate sizes and may be extended for a wide variety of reactions, for performing in situ reaction diagnostics, for chip-scale growth of nanostructures, and for rapid thermal processing of microelectronic and micromechanical devices.

  4. Rapid microfluidic thermal cycler for nucleic acid amplification

    DOEpatents

    Beer, Neil Reginald; Vafai, Kambiz

    2015-10-27

    A system for thermal cycling a material to be thermal cycled including a microfluidic heat exchanger; a porous medium in the microfluidic heat exchanger; a microfluidic thermal cycling chamber containing the material to be thermal cycled, the microfluidic thermal cycling chamber operatively connected to the microfluidic heat exchanger; a working fluid at first temperature; a first system for transmitting the working fluid at first temperature to the microfluidic heat exchanger; a working fluid at a second temperature, a second system for transmitting the working fluid at second temperature to the microfluidic heat exchanger; a pump for flowing the working fluid at the first temperature from the first system to the microfluidic heat exchanger and through the porous medium; and flowing the working fluid at the second temperature from the second system to the heat exchanger and through the porous medium.

  5. Rapid determination of drugs and semivolatile organics by direct thermal desorption ion trap mass spectrometry

    SciTech Connect

    Wise, M.B.; Ilgner, R.H.; Buchanan, M.V.; Guerin, M.R.

    1991-01-01

    Direct thermal desorption of analytes into an ion trap mass spectrometer (ITMS) is being investigated as a technique for the rapid screening of a wide variety of samples for target semivolatile organic compounds. This includes the direct detection of drugs in physiological fluids, semivolatile organic pollutants in water and waste samples, and air pollutants collected on sorbent cartridges. In order to minimize the analysis time, chromatographic separation is not performed on the sample prior to introduction into the ITMS. Instead, selective chemical ionization and tandem mass spectrometry (MS/MS) are used achieve the specificity required for the target analytes. Detection limits are typically 10--50 ppb using a 1 uL aliquot of a liquid sample without preconcentration. Sample turn-around time is 2 to 5 minutes and 3 to 5 target analytes can be quantitatively determined simultaneously. 6 figs.

  6. Symmetry Switching of Negative Thermal Expansion by Chemical Control.

    PubMed

    Senn, Mark S; Murray, Claire A; Luo, Xuan; Wang, Lihai; Huang, Fei-Ting; Cheong, Sang-Wook; Bombardi, Alessandro; Ablitt, Chris; Mostofi, Arash A; Bristowe, Nicholas C

    2016-05-04

    The layered perovskite Ca3-xSrxMn2O7 is shown to exhibit a switching from a material exhibiting uniaxial negative to positive thermal expansion as a function of x. The switching is shown to be related to two closely competing phases with different symmetries. The negative thermal expansion (NTE) effect is maximized when the solid solution is tuned closest to this region of phase space but is switched off suddenly on passing though the transition. Our results show for the first time that, by understanding the symmetry of the competing phases alone, one may achieve unprecedented chemical control of this unusual property.

  7. Chemical Vapor Deposition of Turbine Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Haven, Victor E.

    1999-01-01

    Ceramic thermal barrier coatings extend the operating temperature range of actively cooled gas turbine components, therefore increasing thermal efficiency. Performance and lifetime of existing ceram ic coatings are limited by spallation during heating and cooling cycles. Spallation of the ceramic is a function of its microstructure, which is determined by the deposition method. This research is investigating metalorganic chemical vapor deposition (MOCVD) of yttria stabilized zirconia to improve performance and reduce costs relative to electron beam physical vapor deposition. Coatings are deposited in an induction-heated, low-pressure reactor at 10 microns per hour. The coating's composition, structure, and response to the turbine environment will be characterized.

  8. Rapid scanning thermal lens/laser transmission densitometer.

    PubMed

    Peck, K; Demana, T; Morris, M D

    1988-01-01

    An automated densitometer based on the thermal lens principle is described. The apparatus also operates as a conventional laser transmission densitometer. Comparison of the performance in both modes shows that thermal lens densitometry provides lower detection limits, but that transmission densitometry is more satisfactory at high optical densities. The instrument is characterized with proteins separated by SDS-PAGE and stained with Coomassie Brilliant Blue G250.

  9. Rapid determination of fumigant and industrial chemical residues in food.

    PubMed

    Daft, J L

    1988-01-01

    A gas chromatographic (GC) method is described for the determination of 22 fumigant and industrial chemical residues in a variety of foods. The fumigants and industrial chemicals determined are methyl bromide, methylene chloride, carbon disulfide, chloroform, 1,1-dichloroethane, ethylene dichloride, methyl chloroform, carbon tetrachloride, methylene bromide, propylene dichloride, 2,3-dichloropropene, trichloroethylene, 1,3-dichloropropylene, 1,1,2-trichloroethane, chloropicrin, ethylene dibromide, tetrachloroethylene, propylene dibromide, 1,1,2,2-tetrachloroethane, p-dichlorobenzene, o-dichlorobenzene, and 1,2-dibromo-3-chloropropane. Except for the latter three, the fumigants are determined at 90 degrees C on 3.6 m 20% loaded OV-101 columns with electron-capture and Hall-electroconductivity detectors. The other 3 compounds (o-dichlorobenzene, p-dichlorobenzene, and 1,2-dibromo-3-chloropropane), which elute beyond 30 min on the above columns, are determined at 90 degrees C on 1.8 m 5% loaded OV-101 columns with the same detectors. The ng/g-level fortifications have an overall mean analyte recovery of 70% and a coefficient of variation of 40%. The variety of foods examined includes both fatty and nonfatty food types (e.g., off-the-shelf cooked and uncooked grain-based items, dairy products, fresh and canned fruits and vegetables, and meats). Samples are extracted and cleaned up according to fat content and food type. Samples containing less than 71% fat are extracted by using an aqueous: nonaqueous shakeout (20% acetone solution under isooctane). Most extracts (isooctanes) are analyzed directly. Extracts from samples containing from 21 to 70% fat (e.g., ground beef, pecans, and corn chips) are cleaned up further on micro-Florisil columns to remove excess fat. A few other samples containing more than 71% fat or oil (e.g., butter, salad dressing, and vegetable oil) are diluted directly in isooctane and, depending on the degree of dilution, can be cleaned up further on

  10. Exceptional chemical and thermal stability of zeolitic imidazolate frameworks

    PubMed Central

    Park, Kyo Sung; Ni, Zheng; Côté, Adrien P.; Choi, Jae Yong; Huang, Rudan; Uribe-Romo, Fernando J.; Chae, Hee K.; O’Keeffe, Michael; Yaghi, Omar M.

    2006-01-01

    Twelve zeolitic imidazolate frameworks (ZIFs; termed ZIF-1 to -12) have been synthesized as crystals by copolymerization of either Zn(II) (ZIF-1 to -4, -6 to -8, and -10 to -11) or Co(II) (ZIF-9 and -12) with imidazolate-type links. The ZIF crystal structures are based on the nets of seven distinct aluminosilicate zeolites: tetrahedral Si(Al) and the bridging O are replaced with transition metal ion and imidazolate link, respectively. In addition, one example of mixed-coordination imidazolate of Zn(II) and In(III) (ZIF-5) based on the garnet net is reported. Study of the gas adsorption and thermal and chemical stability of two prototypical members, ZIF-8 and -11, demonstrated their permanent porosity (Langmuir surface area = 1,810 m2/g), high thermal stability (up to 550°C), and remarkable chemical resistance to boiling alkaline water and organic solvents. PMID:16798880

  11. Modeling thermal/chemical/mechanical response of energetic materials

    SciTech Connect

    Baer, M.R.; Hobbs, M.L.; Gross, R.J.

    1995-07-01

    An overview of modeling at Sandia National Laboratories is presented which describes coupled thermal, chemical and mechanical response of energetic materials. This modeling addresses cookoff scenarios for safety assessment studies in systems containing energetic materials. Foundation work is discussed which establishes a method for incorporating chemistry and mechanics into multidimensional analysis. Finite element analysis offers the capabilities to simultaneously resolve reactive heat transfer and structural mechanics in complex geometries. Nonlinear conduction heat transfer, with multiple step finite-rate chemistry, is resolved using a thermal finite element code. Rate equations are solved element-by-element using a modified matrix-free stiff solver This finite element software was developed for the simulation of systems requiring large numbers of finite elements. An iterative implicit scheme, based on the conjugate gradient method, is used and a hemi-cube algorithm is employed for the determination of view factors in surface-to-surface radiation transfer The critical link between the reactive heat transfer and mechanics is the introduction of an appropriate constitutive material model providing a stress-strain relationship for quasi-static mechanics analysis. This model is formally derived from bubble nucleation theory, and parameter variations of critical model parameters indicate that a small degree of decomposition leads to significant mechanical response. Coupled thermal/chemical/mechanical analysis is presented which simulates experiments designed to probe cookoff thermal-mechanical response of energetic materials.

  12. Thermal-chemical Mantle Convection Models With Adaptive Mesh Refinement

    NASA Astrophysics Data System (ADS)

    Leng, W.; Zhong, S.

    2008-12-01

    In numerical modeling of mantle convection, resolution is often crucial for resolving small-scale features. New techniques, adaptive mesh refinement (AMR), allow local mesh refinement wherever high resolution is needed, while leaving other regions with relatively low resolution. Both computational efficiency for large- scale simulation and accuracy for small-scale features can thus be achieved with AMR. Based on the octree data structure [Tu et al. 2005], we implement the AMR techniques into the 2-D mantle convection models. For pure thermal convection models, benchmark tests show that our code can achieve high accuracy with relatively small number of elements both for isoviscous cases (i.e. 7492 AMR elements v.s. 65536 uniform elements) and for temperature-dependent viscosity cases (i.e. 14620 AMR elements v.s. 65536 uniform elements). We further implement tracer-method into the models for simulating thermal-chemical convection. By appropriately adding and removing tracers according to the refinement of the meshes, our code successfully reproduces the benchmark results in van Keken et al. [1997] with much fewer elements and tracers compared with uniform-mesh models (i.e. 7552 AMR elements v.s. 16384 uniform elements, and ~83000 tracers v.s. ~410000 tracers). The boundaries of the chemical piles in our AMR code can be easily refined to the scales of a few kilometers for the Earth's mantle and the tracers are concentrated near the chemical boundaries to precisely trace the evolvement of the boundaries. It is thus very suitable for our AMR code to study the thermal-chemical convection problems which need high resolution to resolve the evolvement of chemical boundaries, such as the entrainment problems [Sleep, 1988].

  13. Atmospheric chemical and thermal structure evolution after one Titan year

    NASA Astrophysics Data System (ADS)

    Coustenis, Athena; Bampasidis, Georgios; Achterberg, Richard; Lavvas, Panayiotis; Vinatier, Sandrine; Nixon, Conor; Jennings, Donald; Teanby, Nicolas; Flasar, F. Michael; Carlson, Ronald; Orton, Glenn; Romani, Paul; Guandique, Ever

    2013-04-01

    Our radiative transfer code (ARTT) was applied to Cassini Composite Infrared Spectrometer (CIRS) data taken during Titan flybys from 2004-2010 and to the 1980 Voyager 1 flyby values inferred from the re-analysis of the Infrared Radiometer Spectrometer (IRIS) spectra [1], as well as to the intervening ground- and space- based observations (such as with ISO, [2]), providing us with a new view of the stratospheric evolution over a Titanian year (V1 encounter Ls=9° was reached in mid-2010). CIRS nadir and limb spectral [3,4] show variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE). We find indication for a weakening of the temperature gradient with warming of the stratosphere and cooling of the lower mesosphere. In addition, we infer precise concentrations for the trace gases and their main isotopologues and find that the chemical composition in Titan's stratosphere varied significantly with latitude during the 6 terrestrial years investigated here, with increased mixing ratios towards the northern latitudes. In particular, we find a maximum enhancement of several gases observed at northern latitudes up to 50°N around mid-2009, at the time of the NSE. We find that this raise is followed by a rapid decrease in chemical inventory in 2010 probably due to changes in the cross vortex mixing or northward migration of the vortex boundary [5,6,7] consistent with the weakening thermal gradient. The finding also ties into the location of the maximum temperature gradient, which appears to be moving northward over the winter/spring season. The return of today's abundances close to the Voyager values (at the same season) is an indication that, as for the Earth, the solar radiation dominates over the other energy sources even at 10AU [8]. Nevertheless, the differences observed for some complex hydrocarbons in the North pole indicate that the other processes could be at play as well

  14. Micro Thermal and Chemical Systems for In Situ Resource Utilization on Mars

    NASA Technical Reports Server (NTRS)

    Wegeng, Robert S.; Sanders, Gerald

    2000-01-01

    Robotic sample return missions and postulated human missions to Mars can be greatly aided through the development and utilization of compact chemical processing systems that process atmospheric gases and other indigenous resources to produce hydrocarbon propellants/fuels, oxygen, and other needed chemicals. When used to reduce earth launch mass, substantial cost savings can result. Process Intensification and Process Miniaturization can simultaneously be achieved through the application of microfabricated chemical process systems, based on the rapid heat and mass transport in engineered microchannels. Researchers at NASA's Johnson Space Center (JSC) and the Department of Energy's Pacific Northwest National Laboratory (PNNL) are collaboratively developing micro thermal and chemical systems for NASA's Mission to Mars program. Preliminary results show that many standard chemical process components (e.g., heat exchangers, chemical reactors and chemical separations units) can be reduced in hardware volume without a corresponding reduction in chemical production rates. Low pressure drops are also achievable when appropriate scaling rules are applied. This paper will discuss current progress in the development of engineered microchemical systems for space and terrestrial applications, including fabrication methods, expected operating characteristics, and specific experimental results.

  15. Boston type 1 keratoprosthesis for chemical and thermal injury.

    PubMed

    Phillips, David L; Hager, Jonathan L; Goins, Kenneth M; Kitzmann, Anna S; Greiner, Mark A; Cohen, Alex W; Welder, Jeffrey D; Wagoner, Michael D

    2014-09-01

    To evaluate the outcome of the Boston type 1 keratoprosthesis (Kpro-1) in eyes with failed interventions for chemical and thermal injury. A retrospective review was performed of every eye with chemical or thermal injury that was treated with a Kpro-1 at a tertiary eye care center between January 1, 2008 and July 1, 2013. The main outcome measures were visual outcome, prosthesis retention, and postoperative complications. Nine eyes met the inclusion criteria, including 7 eyes with alkali burns, 1 eye with an acid burn, and 1 eye with a thermal burn. After a mean follow-up of 40.7 months (range, 29-60 months), the median best-corrected visual acuity was 20/60 (range, 20/15 to no light perception). One eye was ≥20/20, 3 eyes were ≥20/40, and 6 eyes were ≥20/70. The initial Kpro-1 prosthesis was retained in 7 (77.7%) eyes and successfully replaced in the other 2 eyes. One or more serious complications occurred in 6 (66.7%) eyes. These included 2 cases of sterile corneal ulceration with prosthesis extrusion, 2 cases of microbial keratitis (1 bacterial and 1 fungal), 2 cases of bacterial endophthalmitis, and 2 cases of retinal detachments. These complications contributed to visual outcomes of hand motions in 2 eyes and no light perception in 1 eye. The Boston Kpro-1 is associated with highly satisfactory visual outcomes and prosthesis retention in most cases of severe chemical or thermal injury. Serious complications are common and may compromise the final outcome.

  16. Dismountable sample holder apparatus for rapid thermal conductivity measurements based on cryocooler

    NASA Astrophysics Data System (ADS)

    Liu, Huiming; Xu, Dong; Xu, Peng; Huang, R. J.; Xu, Xiangdong; Li, L. F.; Gong, Linghui

    2012-06-01

    A novel apparatus, based on cryocooler, for rapid thermal conductivity measurements between 8 K and 300 K is presented. It consists of a removable sample test bar on which bulk samples can easily be mounted and then placed in the described measurement device. This fast mounting measurement system uses a standard steady-state absolute thermal conductivity measurement and allows for excellent thermal stability and mechanical vibration isolation from the cryocooler. The distinction of this system is rapid mounting and measurement of thermal conductivity with high accuracy and precision in data acquisition. In addition, this system allows for versatility in its use, such as the specific heat and the linear thermal expansion measurement. The design of this apparatus, measurement specification, and thermal conductivity of standard materials measured in this system are presented.

  17. Firearm suppressor having enhanced thermal management for rapid heat dissipation

    DOEpatents

    Moss, William C.; Anderson, Andrew T.

    2014-08-19

    A suppressor is disclosed for use with a weapon having a barrel through which a bullet is fired. The suppressor has an inner portion having a bore extending coaxially therethrough. The inner portion is adapted to be secured to a distal end of the barrel. A plurality of axial flow segments project radially from the inner portion and form axial flow paths through which expanding propellant gasses discharged from the barrel flow through. The axial flow segments have radially extending wall portions that define sections which may be filled with thermally conductive material, which in one example is a thermally conductive foam. The conductive foam helps to dissipate heat deposited within the suppressor during firing of the weapon.

  18. Rapid thermal co-annihilation through bound states in QCD

    NASA Astrophysics Data System (ADS)

    Kim, Seyong; Laine, M.

    2016-07-01

    The co-annihilation rate of heavy particles close to thermal equilibrium, which plays a role in many classic dark matter scenarios, can be "simulated" in QCD by considering the pair annihilation rate of a heavy quark and antiquark at a temperature of a few hundred MeV. We show that the so-called Sommerfeld factors, parameterizing the rate, can be defined and measured non-perturbatively within the NRQCD framework. Lattice measurements indicate a modest suppression in the octet channel, in reasonable agreement with perturbation theory, and a large enhancement in the singlet channel, much above the perturbative prediction. The additional enhancement is suggested to originate from bound state formation and subsequent decay. Making use of a Green's function based method to incorporate thermal corrections in perturbative co-annihilation rate computations, we show that qualitative agreement with lattice data can be found once thermally broadened bound states are accounted for. We suggest that our formalism may also be applicable to specific dark matter models which have complicated bound state structures.

  19. Thermal Spray Based Rapid Manufacturing, Part Refurbishing and Reengineering

    DTIC Science & Technology

    2004-11-30

    comparison algorithm is developed . Fig. 6. Part databse Fig. 7. Part matching Broken Part Data Acquisition (GeoMagic) ----Yes _------ Is It...ground with a diamond wheel. The microstructure and chemical composition is shown in Fig. 14. The average hardness of the deposit was 1100 vickers. Fig

  20. Chemical potential dependence of particle ratios within a unified thermal approach

    SciTech Connect

    Bashir, I. Nanda, H.; Uddin, S.

    2016-06-15

    A unified statistical thermal freeze-out model (USTFM) is used to study the chemical potential dependence of identified particle ratios at mid-rapidity in heavy-ion collisions. We successfully reproduce the experimental data ranging from SPS energies to LHC energies, suggesting the statistical nature of the particle production in these collisions and hence the validity of our approach. The behavior of the freeze-out temperature is studied with respect to chemical potential. The freeze-out temperature is found to be universal at the RHIC and LHC and is close to the QCD predicted phase transition temperature, suggesting that the chemical freeze-out occurs soon after the hadronization takes place.

  1. Millimeter-wave imaging of thermal and chemical signatures.

    SciTech Connect

    Gopalsami, N.

    1999-03-30

    Development of a passive millimeter-wave (mm-wave) system is described for remotely mapping thermal and chemical signatures of process effluents with application to arms control and nonproliferation. Because a large amount of heat is usually dissipated in the air or waterway as a by-product of most weapons of mass destruction facilities, remote thermal mapping may be used to detect concealed or open facilities of weapons of mass destruction. We have developed a focal-plane mm-wave imaging system to investigate the potential of thermal mapping. Results of mm-wave images obtained with a 160-GHz radiometer system are presented for different target scenes simulated in the laboratory. Chemical and nuclear facilities may be identified by remotely measuring molecular signatures of airborne molecules emitted from these facilities. We have developed a filterbank radiometer to investigate the potential of passive spectral measurements. Proof of principle is presented by measuring the HDO spectral line at 80.6 GHz with a 4-channel 77-83 GHz radiometer.

  2. RAPID SCREENING OF ENVIRONMENTAL CHEMICALS FOR ESTROGEN RECEPTOR BINDING CAPACITY

    EPA Science Inventory

    Over the last few years, an increased awareness of endocrine disrupting chemicals (EDCs) and their potential to affect wildlife and humans has produced a demand for practical screening methods to identify endocrine activity in a wide range of environmental and industrial chemical...

  3. RAPID SCREENING OF ENVIRONMENTAL CHEMICALS FOR ESTROGEN RECEPTOR BINDING CAPACITY

    EPA Science Inventory

    Over the last few years, an increased awareness of endocrine disrupting chemicals (EDCs) and their potential to affect wildlife and humans has produced a demand for practical screening methods to identify endocrine activity in a wide range of environmental and industrial chemical...

  4. A hybrid thermal video and FTIR spectrometer system for rapidly locating and characterizing gas leaks

    NASA Astrophysics Data System (ADS)

    Williams, David J.; Wadsworth, Winthrop; Salvaggio, Carl; Messinger, David W.

    2006-08-01

    Undiscovered gas leaks, known as fugitive emissions, in chemical plants and refinery operations can impact regional air quality and present a loss of product for industry. Surveying a facility for potential gas leaks can be a daunting task. Industrial leak detection and repair programs can be expensive to administer. An efficient, accurate and cost effective method for detecting and quantifying gas leaks would both save industries money by identifying production losses and improve regional air quality. Specialized thermal video systems have proven effective in rapidly locating gas leaks. These systems, however, do not have the spectral resolution for compound identification. Passive FTIR spectrometers can be used for gas compound identification, but using these systems for facility surveys is problematic due to their small field of view. A hybrid approach has been developed that utilizes the thermal video system to locate gas plumes using real time visualization of the leaks, coupled with the high spectral resolution FTIR spectrometer for compound identification and quantification. The prototype hybrid video/spectrometer system uses a sterling cooled thermal camera, operating in the MWIR (3-5 μm) with an additional notch filter set at around 3.4 μm, which allows for the visualization of gas compounds that absorb in this narrow spectral range, such as alkane hydrocarbons. This camera is positioned alongside of a portable, high speed passive FTIR spectrometer, which has a spectral range of 2 - 25 μm and operates at 4 cm -1 resolution. This system uses a 10 cm telescope foreoptic with an onboard blackbody for calibration. The two units are optically aligned using a turning mirror on the spectrometer's telescope with the video camera's output.

  5. Free-Electron Lasers, Thermal Diffusion, Chemical Kinetics, and Surgery

    NASA Astrophysics Data System (ADS)

    Edwards, Glenn; Hutson, M. Shane

    2001-11-01

    Experiments demonstrate that the Mark-III FEL is a particularly effective tool for etching soft matter with remarkably little damage surrounding the site when tuned to wavelengths near 6.45 microns. Based on these observatons, human neuorsurgical and ophthalmic procedures were developed and have been performed successfully. A thermodynamic model was proposed to account for the wavelength dependence; however, the dynamics have not been well understood. We have theoretically investigated thermal diffusion and chemical kinetics in a system of alternating layers of protein and water as heated by a Mark-III FEL. The model is representative of cornea and the exposure conditions are comparable to previous experimental FEL investigations. A substantial temperature enhancement develops in the surface layer on the ten-nanosecond time scale. We consider the onset of both the helix-coil transition and chemical bond breaking of collagen in terms of the thermal, chemical, and structural properties of the system as well as laser wavelength and pulse structure.

  6. Experimental studies of thermal and chemical interactions between molten aluminum and water

    SciTech Connect

    Farahani, A.A.; Corradini, M.L.

    1995-09-01

    The possibility of rapid physical and chemical aluminum/water interactions during a core melt accident in a noncommercial reactor (e.g., HFIR, ATR) has resulted in extensive research to determine the mechanism by which these interactions occur and propagate on an explosive time scale. These events have been reported in nuclear testing facilities, i.e., during SPERT 1D experiment, and also in aluminum casting industries. Although rapid chemical reactions between molten aluminum and water have been subject of many studies, very few reliable measurements of the extent of the chemical reactions have thus far been made. We have modified an existing 1-D shock tube facility to perform experiments in order to determine the extent of the explosive thermal/chemical interactions between molton aluminum and water by measuring important physical quantities such as the maximum dynamic pressure and the amount of the generated hydrogen. Experimental results show that transient pressures greater than 69 MPa with a rise time of less than 125 {mu}sec can occur as the result of the chemical reaction of 4.2 grams of molton aluminum (approximately 15% of the total mass of the fuel of 28 grams) at 980 C with room temperature water.

  7. Nonperturbative production of matter and rapid thermalization after MSSM inflation

    NASA Astrophysics Data System (ADS)

    Allahverdi, Rouzbeh; Ferrantelli, Andrea; Garcia-Bellido, Juan; Mazumdar, Anupam

    2011-06-01

    A gauge invariant combination of LLe sleptons within the minimal supersymmetric standard model is one of the few inflaton candidates that can naturally explain population of the observable sector and creation of matter after inflation. After the end of inflation, the inflaton oscillates coherently about the minimum of its potential, which is a point of enhanced gauged symmetry. This results in bursts of nonperturbative production of the gauge/gaugino and (s)lepton quanta. The subsequent decay of these quanta is very fast and leads to an extremely efficient transfer of the inflaton energy to (s)quarks via instant preheating. Around 20% of the inflaton energy density is drained during every inflaton oscillation. However, all of the standard model degrees of freedom (and their supersymmetric partners) do not thermalize immediately, since the large inflaton vacuum expectation value breaks the electroweak symmetry. After about 100 oscillations—albeit within one Hubble time—the amplitude of inflaton oscillations becomes sufficiently small, and all of the degrees of freedom will thermalize. This provides by far the most efficient reheating of the universe with the observed degrees of freedom.

  8. Desorption Flame-Induced Atmospheric Pressure Chemical Ionization Mass Spectrometry for Rapid Real-World Sample Analysis

    PubMed Central

    Cheng, Sy-Chyi; Chen, Shih-His; Shiea, Jentaie

    2017-01-01

    Flame-induced atmospheric pressure chemical ionization (FAPCI) is a solvent and high voltage-free APCI technique. It uses a flame to produce charged species that reacts with analytes for ionization, and generates intact molecular ions from organic compounds with minimal fragmentation. In this study, desorption FAPCI/MS was developed to rapidly characterize thermally stable organic compounds in liquid, cream, and solid states. Liquid samples were introduced into the ion source through a heated nebulizer, and the analytes formed in the heated nebulizer reacted with charged species in the source. For cream and solid sample analysis, the samples were positioned near the flame of the FAPCI source for thermal desorption and ionization. This approach provided a useful method to directly characterize samples with minimal pretreatment. Standards and real-world samples, such as drug tablets, ointment, and toy were analyzed to demonstrate the capability of desorption FAPCI/MS for rapid organic compound analysis. PMID:28573084

  9. Rapid Chemical Ordering in Supercooled Liquid Cu46Zr54

    SciTech Connect

    Wessels, Victor; Gangopadhyay, Anup; Sahu, K. K.; Hyers, R. W.; Canepari, S. M.; Rogers, J. R.; Kramer, Matthew J.; Goldman, Alan; Robinson, D.; Lee, Jae W; Morris, James R; Kelton, K. F.

    2011-01-01

    Evidence for abrupt chemical ordering in a supercooled Cu46Zr54 liquid, obtained from high energy x-ray diffraction in a containerless processing environment, is presented. Relatively sudden changes were observed in the topological and chemical short-range order near 850oC, a temperature significantly below the liquidus and above the glass transition temperatures. A peak in the specific heat was observed with supercooling, with an onset near 850oC, the same temperature as the onset of chemical ordering, and a maximum near 700oC, consistent with the prediction of a molecular dynamics calculation using embedded atom potentials. The dominant short-range order below 850oC is incompatible with that of the primary crystallizing phases. This, and the possible development of strongly bonded, chemically ordered clustersmay explain unlikely bulk metallic glass formation in Cu-Zr and other binary alloys.

  10. Rapid guide to hazardous chemicals in the workplace

    SciTech Connect

    Sax, I.N.; Lewis, R.J. Sr.

    1986-01-01

    This guide gives quick access to hazard data on almost 700 chemicals commonly found in the workplace. Alphabetically listed, each entry covers a specific chemical, standards and recommendations for exposure, its physical properties, and its toxic and hazard rating. A CAS, RTECS and DOT number identifies each substance; standards and recommendations cover its OSHA Permissible Exposure Limit, ACGIH Threshold Limit Value, MAKS, and DOT hazard classification. Physical properties include form, color, and odor. Here too is additional identifying information such as chemical formulas and well-known synonyms. The Toxic and Hazard Review summarizes hazards associated with the chemicals, revealing their: acute, immediate, chronic, and delayed effects; toxic or hazardous decomposition products; flammable and explosive properties; and incompatible materials and instabilities. This book is a reference source.

  11. Anisotropic turbulent thermal diffusion and thermal convection in a rapidly rotating fluid sphere

    NASA Astrophysics Data System (ADS)

    Ivers, D. J.; Phillips, C. G.

    2012-01-01

    Estimates of the molecular values of magnetic, viscous and thermal diffusion suggest that the state of the Earth's core is turbulent and that complete numerical simulation of the geodynamo is not realizable at present. Large eddy simulation of the geodynamo with modelling of the sub-grid scale turbulence must be used. Current geodynamo models effectively model the sub-grid scale turbulence with isotropic diffusivities larger than the molecular values appropriate for the core. In the Braginsky and Meytlis (1990) picture of core turbulence the thermal and viscous diffusivities are enhanced up to the molecular magnetic diffusivity in the directions of the rotation axis and mean magnetic field. We neglect the mean magnetic field herein to isolate the effects of anisotropic thermal diffusion, enhanced or diminished along the rotation axis, and explore the instability of a steady conductive basic state with zero mean flow in the Boussinesq approximation. This state is found to be more stable (less stable) as the thermal diffusion parallel to the rotation axis is increased (decreased), if the transverse thermal diffusion is fixed. To examine the effect of simultaneously varying the diffusion along and transverse to the rotation axis, the Frobenius norm is used to control for the total thermal diffusion. When the Frobenius norm of the thermal diffusion tensor is fixed, it is found that increasing the thermal diffusion parallel to the rotation axis is destabilising. This result suggests that, for a fixed total thermal diffusion, geodynamo codes with anisotropic thermal diffusion may operate at lower modified Rayleigh numbers.

  12. Rapid chemical agent identification by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Yuan-Hsiang; Farquharson, Stuart

    2001-08-01

    Although the Chemical Weapons Convention prohibits the development, production, stockpiling, and use of chemical warfare agents (CWAs), the use of these agents persists due to their low cost, simplicity in manufacturing and ease of deployment. These attributes make these weapons especially attractive to low technology countries and terrorists. The military and the public at large require portable, fast, sensitive, and accurate analyzers to provide early warning of the use of chemical weapons. Traditional laboratory analyzers such as the combination of gas chromatography and mass spectroscopy, although sensitive and accurate, are large and require up to an hour per analysis. New, chemical specific analyzers, such as immunoassays and molecular recognition sensors, are portable, fast, and sensitive, but are plagued by false-positives (response to interferents). To overcome these limitations, we have been investigating the potential of surface-enhanced Raman spectroscopy (SERS) to identify and quantify chemical warfare agents in either the gas or liquid phase. The approach is based on the extreme sensitivity of SERS demonstrated by single molecule detection, a new SERS material that we have developed to allow reproducible and reversible measurements, and the molecular specific information provided by Raman spectroscopy. Here we present SER spectra of chemical agent simulants in both the liquid and gas phase, as well as CWA hydrolysis phase.

  13. Thermal effects in rapid directional solidification - Linear theory

    NASA Technical Reports Server (NTRS)

    Huntley, D. A.; Davis, S. H.

    1993-01-01

    We study the morphological instability of the planar solid/liquid interface for a unidirectionally-solidified dilute binary mixture. We use a model developed by Boettinger et al. (1985, 1986), Aziz (1982), and Jackson et al. (1980), which allows for nonequilibrium effects on the interface through velocity-dependent segregation and attachment kinetics. Two types of instabilities are found in the linear stability analysis: (1) a cellular instability, and (2) an oscillatory instability driven by disequilibrium effects. Merchant and Davis (1990) characterized these instabilities subject to the frozen-temperature approximation (FTA). The present work relaxes the FTA by including the effects of latent heat and the full temperature distribution. Thermal effects slightly postpone the onset of the cellular instability but dramatically postpone the onset of the oscillatory instability; however, the absolute-stability conditions, at which at high speed the cellular and oscillatory instabilities are suppressed, remain unchanged from the FTA.

  14. Examination of lignocellulosic fibers for chemical, thermal, and separations properties: Addressing thermo-chemical stability issues

    NASA Astrophysics Data System (ADS)

    Johnson, Carter David

    Natural fiber-plastic composites incorporate thermoplastic resins with fibrous plant-based materials, sometimes referred to as biomass. Pine wood mill waste has been the traditional source of natural fibrous feedstock. In anticipation of a waste wood shortage other fibrous biomass materials are being investigated as potential supplements or replacements. Perennial grasses, agricultural wastes, and woody biomass are among the potential source materials. As these feedstocks share the basic chemical building blocks; cellulose, hemicellulose, and lignin, they are collectively called lignocellulosics. Initial investigation of a number of lignocellulosic materials, applied to fiber-plastic composite processing and material testing, resulted in varied results, particularly response to processing conditions. Less thermally stable lignocellulosic filler materials were physically changed in observable ways: darkened color and odor. The effect of biomass materials' chemical composition on thermal stability was investigated an experiment involving determination of the chemical composition of seven lignocellulosics: corn hull, corn stover, fescue, pine, soy hull, soy stover, and switchgrass. These materials were also evaluated for thermal stability by thermogravimetric analysis. The results of these determinations indicated that both chemical composition and pretreatment of lignocellulosic materials can have an effect on their thermal stability. A second study was performed to investigate what effect different pretreatment systems have on hybrid poplar, pine, and switchgrass. These materials were treated with hot water, ethanol, and a 2:1 benzene/ethanol mixture for extraction times of: 1, 3, 6, 12, and 24 hours. This factorial experiment demonstrated that both extraction time and medium have an effect on the weight percent of extractives removed from all three material types. The extracted materials generated in the above study were then subjected to an evaluation of thermal

  15. Methods for the rapid detection of biological and chemical weapons

    SciTech Connect

    Castro, A.; Hemberger, P.H.; Swanson, B.I.

    1997-08-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). This work undertook the development of technology for the detection of chemical and biological agents. The project consisted of three tasks: (1) modifying a transportable mass spectrometer for the detection of chemical gents; (2) demonstrating the detection of a specific bacterial DNA sequence using a fluorescence-based single- copy gene detector; and (3) upgrading a surface acoustic wave measurement station.

  16. Thermal and chemical degradation of inorganic membrane materials. Topical report

    SciTech Connect

    Krishnan, G.N.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

    1994-04-01

    This report describes the results of a literature review to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate gaseous products produced by the gasification or combustion of coal in fixed-, fluidized-, and entrained-bed gasifiers, direct coal-fired turbines, and pressurized-fluidized-bed combustors. Several impurities, such as H{sub 2}S, NH{sub 3}, SO{sub 2}, NO{sub x}, and trace metal compounds are generated during coal conversion, and they must be removed from the coal gas or the combustor flue gas to meet environmental standards. The use of membranes to separate these noxious gases is an attractive alternative to their removal by sorbents such as zinc titanate or calcium oxide. Inorganic membranes that have a high separation efficiency and exhibit both thermal and chemical stability would improve the economics of power generation from coal. The U.S. Department of Energy is supporting investigations to develop inorganic membranes for separating hydrogen from coal gas streams and noxious impurities from hot coal- and flue-gas streams. Membrane materials that have been investigated in the past include glass (silica), alumina, zirconia, carbon, and metals (Pd and Pt).

  17. Chemical kinetic performance losses for a hydrogen laser thermal thruster

    NASA Technical Reports Server (NTRS)

    Mccay, T. D.; Dexter, C. E.

    1985-01-01

    Projected requirements for efficient, economical, orbit-raising propulsion systems have generated investigations into several potentially high specific impulse, moderate thrust, advanced systems. One of these systems, laser thermal propulsion, utilizes a high temperature plasma as the enthalpy source. The plasma is sustained by a focused laser beam which maintains the plasma temperature at levels near 20,000 K. Since such temperature levels lead to total dissociation and high ionization, the plasma thruster system potentially has a high specific impulse decrement due to recombination losses. The nozzle flow is expected to be sufficiently nonequilibrium to warrant concern over the achievable specific impluse. This investigation was an attempt at evaluation of those losses. The One-Dimensional Kinetics (ODK) option of the Two-Dimensional Kinetics (TDK) Computer Program was used with a chemical kinetics rate set obtained from available literature to determine the chemical kinetic energy losses for typical plasma thruster conditions. The rates were varied about the nominal accepted values to band the possible losses. Kinetic losses were shown to be highly significant for a laser thermal thruster using hydrogen. A 30 percent reduction in specific impulse is possible simply due to the inability to completely extract the molecular recombination energy.

  18. Subduction initiation by thermal chemical plumes: Numerical studies

    NASA Astrophysics Data System (ADS)

    Ueda, Kosuke; Gerya, Taras; Sobolev, Stephan V.

    2008-12-01

    Prior suggestions for the initiation of subduction have included sediment loading, compression, and plate reconfiguration as potential triggers. Here, we investigate the possibility of subduction initiation by the interaction of the lithosphere with a buoyant mantle plume. Numerical testing of this hypothesis has been conducted in 2D with the I2VIS thermo-mechanical code accounting for phase transitions and a viscoplastic model of a thin oceanic lithosphere hit by a partially molten thermal-chemical or purely thermal plume. We demonstrate that a mantle plume can break the lithosphere and initiate self-sustaining subduction, provided the plume causes a critical local weakening of the lithospheric material above it. The intensity of the required weakening depends on the plume volume, plume buoyancy, and the thickness of the lithosphere and is the highest for the least buoyant purely thermal plumes. Another necessary condition is the presence of high-pressure fluids at the slab upper interface, reducing the effective friction coefficient there to very low values. Based on our results, we suggest that sheet-like instabilities of the Archean mantle convection could have initiated subduction on Earth where ocean was already present in less stable tectonic settings, provided that mantle plumes (sheets) at that time were rich in water and melt, which could drastically reduce the effective friction coefficient in the lithosphere above the plume. Our numerical models are also in good agreement with suggested concepts for corona formation on Venus.

  19. Computational thermal, chemical, fluid, and solid mechanics for geosystems management.

    SciTech Connect

    Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu

    2011-09-01

    This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.

  20. Dumping pump and treat: rapid cleanups using thermal technology

    SciTech Connect

    Newmark, R.L.; Aines, R.D.

    1997-03-11

    Underground spills of volatile hydrocarbons are often difficult to clean up, especially if the contaminants are present in or below the water table as a separate liquid-organic phase. Excavating and treating the contaminated soil may not be practical or even possible if the affected zone is relatively deep. Merely pumping groundwater has proven to be ineffective because huge amounts of water must be flushed through the contaminated area to clean it; even then the contaminants may not be completely removed. Due to the low solubility of most common contaminants, such pump and treat systems can be expected to take decades to centuries to actually clean a site. Today, many sites are required to pump and treat contaminated groundwater even though there is no expectation that the site will be cleaned. In these cases, the pumps simply control the spread of the contaminant, while requiring a continuous flow of money, paperwork, and management attention. Although pump and treat systems are relatively inexpensive to operate, they represent along term cost. Most importantly, they rarely remove enough contaminant to change the property`s status. Although a pump and treat system can offer compliance in a regulatory sense, it doesn`t solve the site`s liability problem. Thermal methods promise to solve this dilemma by actually cleaning a property in a short time period, thus limiting the period of liability. This may involve cleaning a site to closure during the initial contaminant-removal phase, or removal of the majority of the contaminant so that natural processes such as bioremediation can return the site to pristine condition over a period of years, without further owner intervention. Today`s regulatory environment encourages this approach through efforts such as the brownfields initiatives. In either case, this requires a strong commitment on the part of the site owner. Most if not all the cleanup occurs within the first year or so, and nearly all the cost. In our

  1. Rapid thermal processing in the manufacturing technology of contacts to InP-based photonic devices

    NASA Astrophysics Data System (ADS)

    Katz, Avishay

    1991-04-01

    Rapid thermal alloying and sintering of metal ohmic contacts such as AuBe PtTFi and W to InP-based materials is shown to perform with better electrical properties than the same contacts heated by means of conventional furnace. The metalsemiconductor interfacial reactions induced by the rapid thermal processing were much shallower than those formed during the conventional heating cycle at the same temperature however with a negligible influence on the overall stresses developed in the film. These results demonstrate the superiority of the rapid thermal processing over the conventional furnace heating in sintering the metal electrical contacts and its potential while integrated into the overall manufacturing process sequence of the InP based photonic devices.

  2. Coupled Thermal-Chemical-Mechanical Modeling of Validation Cookoff Experiments

    SciTech Connect

    ERIKSON,WILLIAM W.; SCHMITT,ROBERT G.; ATWOOD,A.I.; CURRAN,P.D.

    2000-11-27

    The cookoff of energetic materials involves the combined effects of several physical and chemical processes. These processes include heat transfer, chemical decomposition, and mechanical response. The interaction and coupling between these processes influence both the time-to-event and the violence of reaction. The prediction of the behavior of explosives during cookoff, particularly with respect to reaction violence, is a challenging task. To this end, a joint DoD/DOE program has been initiated to develop models for cookoff, and to perform experiments to validate those models. In this paper, a series of cookoff analyses are presented and compared with data from a number of experiments for the aluminized, RDX-based, Navy explosive PBXN-109. The traditional thermal-chemical analysis is used to calculate time-to-event and characterize the heat transfer and boundary conditions. A reaction mechanism based on Tarver and McGuire's work on RDX{sup 2} was adjusted to match the spherical one-dimensional time-to-explosion data. The predicted time-to-event using this reaction mechanism compares favorably with the validation tests. Coupled thermal-chemical-mechanical analysis is used to calculate the mechanical response of the confinement and the energetic material state prior to ignition. The predicted state of the material includes the temperature, stress-field, porosity, and extent of reaction. There is little experimental data for comparison to these calculations. The hoop strain in the confining steel tube gives an estimation of the radial stress in the explosive. The inferred pressure from the measured hoop strain and calculated radial stress agree qualitatively. However, validation of the mechanical response model and the chemical reaction mechanism requires more data. A post-ignition burn dynamics model was applied to calculate the confinement dynamics. The burn dynamics calculations suffer from a lack of characterization of the confinement for the flaw

  3. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.

    2003-01-01

    An apparatus and method for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution are provided. The apparatus includes a modified particle size magnifier for producing activated aerosol particles and a collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical methods. The method provided for on-line measurement of chemical composition of aerosol particles includes exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  4. Apparatus for rapid measurement of aerosol bulk chemical composition

    DOEpatents

    Lee, Yin-Nan E.; Weber, Rodney J.; Orsini, Douglas

    2006-04-18

    An apparatus for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution is provided. The apparatus includes an enhanced particle size magnifier for producing activated aerosol particles and an enhanced collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical means. Methods for on-line measurement of chemical composition of aerosol particles are also provided, the method including exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; and flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

  5. Experimental results of chemical recording using thermally sensitive liposomes

    NASA Astrophysics Data System (ADS)

    Tanner, Maria E.; Vasievich, Elizabeth A.; Protz, Jonathan M.

    2008-04-01

    A new generation of inertial measurement technology is being developed enabling a 10-micron particle to be "aware" of its geospatial location and respond to this information. The proposed approach combines an inertially-sensitive nano-structure or nano fluid/structure system with a nano-sized chemical reactor that functions as an analog computer. By using chemistry to perform the necessary computational steps in our device, it is possible to overcome traditional limitations on device size. The proposed nanodevice utilizes mechanical sensing and chemical recording to record the time history of various state variables. Using a micro-track containing regions of different temperatures and thermally-sensitive liposomes (TSL), a range of accelerations can be recorded and the position determined. Through careful design, TSL can be developed that have unique transition temperatures and each class of TSL will contain a unique DNA sequence that serves as an identifier. Acceleration can be detected through buoyancy-driven convection. As the liposomes travel to regions of warmer temperature, they will release their contents at the recording site, thus documenting the acceleration. This paper will present the initial proof-of-concept experimental results achieved from chemical recording of the state variable temperature. The experiment focuses on the liposome release of the DNA due to temperature variations and subsequent binding and recording of the time history. These results prove the feasibility of this method of sensing and recording of the history of state variables.

  6. Chemical regulation on fire: rapid policy advances on flame retardants.

    PubMed

    Cordner, Alissa; Mulcahy, Margaret; Brown, Phil

    2013-07-02

    Chemicals that are widely used in consumer products offer challenges to product manufacturers, risk managers, environmental regulators, environmental scientists, and the interested public. However, the factors that cause specific chemicals to rise to the level of regulatory, scientific, and social movement concern and scrutiny are not well documented, and scientists are frequently unclear about exactly how their research impacts policy. Through a case study of advocacy around flame retardant chemicals, this paper traces the pathways through which scientific evidence and concern is marshaled by both advocacy groups and media sources to affect policy change. We focus our analysis around a broad coalition of environmental and public health advocacy organizations and an investigative journalism series published in 2012 in the Chicago Tribune. We demonstrate that the Tribune series both brought the issue to a wider public audience and precipitated government action, including state policy revisions and federal Senate hearings. We also show how a broad and successful flame retardant coalition developed, leveraged a media event, and influenced policy at multiple institutional levels. The analysis draws on over 110 in-depth interviews, literature and Web site reviews, and observations at a flame retardant manufacturing company, government offices, and scientific and advocacy conferences.

  7. Rapid determination of nicotine in urine by direct thermal desorption ion trap mass spectrometry

    SciTech Connect

    Wise, M.B.; Ilgner, R.H.; Guerin, M.R.

    1990-01-01

    The measurement of nicotine and cotinine in physiological fluids (urine, blood serum, and saliva) is widely used as a means of assessing human exposure to environmental tobacco smoke (ETS). Although numerous analytical methods exist for these measurements, they generally involve extensive sample preparation which increases cost and decreases sample throughput. We report the use of thermal desorption directly into an ion trap mass spectrometer (ITMS) for the rapid determination of nicotine and cotinine in urine. A 1{mu}L aliquot of urine is injected into a specially designed inlet and flash vaporized directly into an ITMS through an open-split capillary restrictor interface. Isobutane chemical ionization is used to generate (M+H){sup +} ions of the analytes and collision induced dissociation is used to generate characteristic fragment ions which are used to confirm their identity. Quantification is achieved by integrating the ion current for the characteristic ions and comparing with an external working curve. Detection limits are approximately 50 pg per analyte and the sample turnaround time is approximately 3 minutes without the need for extensive sample preparation. 12 refs., 5 figs.

  8. Stabilization of thin tungsten films on silicon during rapid thermal annealing in nitrogen

    SciTech Connect

    Smith, P.M.

    1991-01-01

    Thin W films on Si, deposited by electron-beam evaporation or sputtering, are shown to be stabilized against silicidation by a N[sub 2] ambient during rapid thermal annealing to temperatures of 1100[degree]C. The behavior of the W films in contact with Si was monitored following anneals in Ar and N[sub 2] ambients. Tungsten films annealed in an Ar ambient reacted fully to form the stable silicide, WSi[sub 2], while films annealed in N[sub 2] remained elemental W. The stability of W films with incorporated N was studied further by subsequent annealing in an Ar ambient. Complete stabilization of the W films was only achieved for N doses above 2.0 [times] 10[sup 17] N atoms/cm[sub 2]. At lower doses, a continual supply of N was necessary to maintain the stabilization by consumption of mobile Si at the interface. In contrast to films deposited by e-beam evaporation or sputtering, films deposited by chemical vapor deposition (CVD) reacted to form WSi[sub 2], regardless of the annealing ambient, at a substantially faster rate than the other samples. AES measurements show this reaction is the result of an absence of measurable O in the CVD films.

  9. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    SciTech Connect

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  10. Hyper-Rapid thermal defect annealing during grinding of ZnO powders

    NASA Astrophysics Data System (ADS)

    Kakazey, M. G.; Vlasova, M.; Dominguez-Patino, M.; Dominguez-Patino, G.; Gonzalez-Rodriguez, G.; Salazar-Hernandez, B.

    2002-11-01

    We report on the changes in the defect structure of ZnO particles that take place during the grinding of pure ZnO powders and mixtures ZnO-SnO2 and ZnO-TiO2 powders. The qualitative differences in the electron paramagnetic resonance spectra for different specimens were discussed in the context of the hyper-rapid high-temperature spikes created in ZnO particles during mechanical treatment. The thermal spikes cause the defect structure to undergo annealing. The spike duration of the hyper-rapid thermal defects annealing was dependent on the heat conductivity of the ZnO particle environment.

  11. Rapid PCR protocols for forensic DNA typing on six thermal cycling platforms.

    PubMed

    Butts, Erica L R; Vallone, Peter M

    2014-11-01

    Rapid PCR protocols for the amplification of typing STR multiplexes were evaluated on six different thermal cyclers. Through the use of a faster DNA polymerase coupled with the use of rapid thermal cyclers the amplification cycling times were reduced down to as little as 14 min using PCR primers from the commercially available multiplex STR typing kit Identifiler. Previously described two-step and three-step thermal cycling protocols were evaluated for the six thermal cyclers on 95 unique single-source DNA extracts. CE characterization of the PCR products indicates good peak balance between loci (median values greater than 0.84), and N minus four stutter ratios on averages were 30 to 40% higher than for standard Identifiler PCR conditions. Nonspecific amplification artifacts were observed, but were not observed to migrate within the allele calling bins. With the exception of one locus (D18S51) in a single sample, genotyping results were concordant with manufacturer's recommended amplification conditions utilizing standard thermal cycling procedures. Assay conditions were robust enough to routinely amplify 250 to 500 pg of template DNA. This work describes the protocols for the rapid PCR amplification of STR multiplexes on various PCR thermal cyclers with the future intent to support validation for typing single-source samples in a database laboratory.

  12. Negative thermal expansion in functional materials: controllable thermal expansion by chemical modifications.

    PubMed

    Chen, Jun; Hu, Lei; Deng, Jinxia; Xing, Xianran

    2015-06-07

    Negative thermal expansion (NTE) is an intriguing physical property of solids, which is a consequence of a complex interplay among the lattice, phonons, and electrons. Interestingly, a large number of NTE materials have been found in various types of functional materials. In the last two decades good progress has been achieved to discover new phenomena and mechanisms of NTE. In the present review article, NTE is reviewed in functional materials of ferroelectrics, magnetics, multiferroics, superconductors, temperature-induced electron configuration change and so on. Zero thermal expansion (ZTE) of functional materials is emphasized due to the importance for practical applications. The NTE functional materials present a general physical picture to reveal a strong coupling role between physical properties and NTE. There is a general nature of NTE for both ferroelectrics and magnetics, in which NTE is determined by either ferroelectric order or magnetic one. In NTE functional materials, a multi-way to control thermal expansion can be established through the coupling roles of ferroelectricity-NTE, magnetism-NTE, change of electron configuration-NTE, open-framework-NTE, and so on. Chemical modification has been proved to be an effective method to control thermal expansion. Finally, challenges and questions are discussed for the development of NTE materials. There remains a challenge to discover a "perfect" NTE material for each specific application for chemists. The future studies on NTE functional materials will definitely promote the development of NTE materials.

  13. Comparison of rapid screening assays using organic chemicals

    SciTech Connect

    Beach, S.A.; Robideau, R.R.

    1994-12-31

    In a continuation of a study presented last year using metals, the sensitivity of short term toxicity tests is examined using common organic chemicals. In toxicity testing, the focus has shifted from the traditional long-term studies utilizing the mortality of complex, multicellular eukaryotic organisms as the endpoint towards short-term studies in which transformation of biochemical pathways are monitored. The relative sensitivity of aquatic screening techniques are compared to the standardized 48-hr Daphnia magna and Ceriodaphnia dubia, 96-hr fathead minnow and 96-hr algal acute assays. The short-term test procedures investigated are: dehydrogenase enzyme activity assays utilizing triphenyltetrazolium chloride (TTC) and resazurin as the calorimetric indicators; TOXI-Chromotest, inhibition of {beta}-galactosidase; reduction in bioluminescence output utilizing the Microtox{reg_sign} test; nitrification inhibition assays with a commercial preparation of nitrifying bacteria (Nitroseed{trademark}) and municipal activated sludge; respiration inhibition assays with a commercial preparation of heterotrophic bacteria (Polytox{reg_sign}) and activated sludge; inhibition of root growth in terrestrial plants; and galactosidase inhibition through the use of a fluorometrically tagged substrate with the Daphnia magna IQ{trademark} test. Toxicity values generated by this laboratory on commonly used organic chemicals are compared.

  14. Rapid thermal cycling of metal-supported solid oxide fuel cellmembranes

    SciTech Connect

    Matus, Yuriy B.; De Jonghe, Lutgard C.; Jacobson, Craig P.; Visco, Steven J.

    2004-01-02

    Solid oxide fuel cell (SOFC) membranes were developed in which zirconia-based electrolyte thin films were supported by a composite metal/ceramic electrode, and were subjected to rapid thermal cycling between 200 and 800 C. The effects of this cycling on membrane performance were evaluated. The membranes, not yet optimized for performance, showed a peak power density of 350mW/cm2at 900 C in laboratory-sized SOFCs that was not affected by the thermal cycling. This resistance to cycling degradation is attributed to the close matching of thermal expansion coefficient of the cermet support electrode with that of the zirconia electrolyte.

  15. (Homogeneous-heterogeneous combustion: Thermal and chemical coupling)

    SciTech Connect

    Not Available

    1992-01-01

    This is a program to characterize fundamental issues and practical applications of homogeneous-heterogeneous reactions. Fundamental studies of reactions at low pressures and of boundary layer characterization give microscopic information on the processes. Ignition and extinction studies over simple geometries give basic bifurcation behavior with which to characterize multiple steady states and their stabilities and hopefully to identify the types of behavior which may occur. Use of catalytic monoliths will permit examination of the chemical and thermal performance of one of the most important types of geometries in which both types of reaction can occur. Modeling will tie all of these aspects together by showing how individual components interact, Predicting performance of monoliths, and providing the framework for translating these ideas into technological contexts.

  16. Thermal energy storage. [by means of chemical reactions

    NASA Technical Reports Server (NTRS)

    Grodzka, P. G.

    1975-01-01

    The principles involved in thermal energy storage by sensible heat, chemical potential energy, and latent heat of fusion are examined for the purpose of evolving selection criteria for material candidates in the low ( 0 C) and high ( 100 C) temperature ranges. The examination identifies some unresolved theoretical considerations and permits a preliminary formulation of an energy storage theory. A number of candidates in the low and high temperature ranges are presented along with a rating of candidates or potential candidates. A few interesting candidates in the 0 to 100 C region are also included. It is concluded that storage by means of reactions whose reversibility can be controlled either by product removal or by catalytic means appear to offer appreciable advantages over storage with reactions whose reversability cannot be controlled. Among such advantages are listed higher heat storage capacities and more favorable options regarding temperatures of collection, storage, and delivery. Among the disadvantages are lower storage efficiencies.

  17. Coupled thermal/chemical/mechanical modeling of energetic materials in ALE3D

    SciTech Connect

    Nichols, A.L.; Couch, R.; Maltby, J.D.; McCallen, R.C.; Otero, I.; Sharp, R.

    1996-10-01

    We must improve our ability to model the response of energetic ma@ to thmnal stimuli and the processes involved m the energetic response. Traditionally, the analyses of energeuc have mvolved coupled thermal chemical reaction codes. This provides only a reasonable estimate of the dw and location of ensuing rapid reaction. To predict the violence of the reaction, the m cal motion must be included in the wide range of time scales as with the th@ hazard. Ile ALE3D code has been modified to the hazards associated with heaung energetic ma@ in weapons. We have merged the thermal models from TOPAZ3D and the chemistry models &vel@ in Chemical TOPAZ into ALE3D. We have developed and use an impMt time step option to efficiently and accurately compute the hours that the energetic material can take to react. Since on these longer fim scales materials can be expected to have signifimt motion, it is even more important to provide high- ordcr advection for all components, including the chemical species. We will show an example cook-off problem to illustrate these capabilities.

  18. Degradation of Teflon(tm) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1998-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(R) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(R) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(R) FEP.

  19. Degradation of Teflon(trademark) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1999-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(trademark) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(trademark) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(trademark) FEP.

  20. Degradation of Teflon(tm) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline A.; Powers, Charles E.; Viens, Michael J.; Ayres-Treusdell, Mary T.; Munoz, Bruno F.

    1998-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon' FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(registered trademark) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(registered trademark) FEP.

  1. Degradation of Teflon(tm) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline A.; Powers, Charles E.; Viens, Michael J.; Ayres-Treusdell, Mary T.; Munoz, Bruno

    1998-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon' FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon FEP.

  2. Modeling of forced flow/thermal gradient chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Smith, A.W. )

    1992-09-01

    The forced flow/thermal gradient chemical vapor infiltration process (FCVI) has proven to be a successful technique for fabrication of ceramic matrix composites. It is particularly attractive for thick components which cannot be fabricated using the conventional, isothermal method (ICVI). Although it offers processing times that are at least an order of magnitude shorter than ICVI, FCVI has not been used to fabricate parts of complex geometry and is perceived by some to be unsuitable for such components. The major concern Is that selection and control of the flow pattern and thermal profile for optimum infiltration can be a difficult and costly exercise. In order to reduce this effort, we are developing a computer model for FCVI that simulates the densification process for given component geometry, reactor configuration and operating parameters. Used by a process engineer, this model can dramatically reduce the experimental effort needed to obtain uniform densification. A one-dimensional process model, described in a previous interim report, has demonstrated good agreement with experimental results in predicting overall densification time and density uniformity during processing and the effect of various fiber architectures and operating parameters on these process issues. This model is fundamentally unsuitable for more complex geometries, however, and extension to two- and three-dimensions is necessary. This interim report summarizes our progress since the previous interim report toward development of a finite volume'' model for FCVI.

  3. Modeling of forced flow/thermal gradient chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Smith, A.W.

    1992-09-01

    The forced flow/thermal gradient chemical vapor infiltration process (FCVI) has proven to be a successful technique for fabrication of ceramic matrix composites. It is particularly attractive for thick components which cannot be fabricated using the conventional, isothermal method (ICVI). Although it offers processing times that are at least an order of magnitude shorter than ICVI, FCVI has not been used to fabricate parts of complex geometry and is perceived by some to be unsuitable for such components. The major concern Is that selection and control of the flow pattern and thermal profile for optimum infiltration can be a difficult and costly exercise. In order to reduce this effort, we are developing a computer model for FCVI that simulates the densification process for given component geometry, reactor configuration and operating parameters. Used by a process engineer, this model can dramatically reduce the experimental effort needed to obtain uniform densification. A one-dimensional process model, described in a previous interim report, has demonstrated good agreement with experimental results in predicting overall densification time and density uniformity during processing and the effect of various fiber architectures and operating parameters on these process issues. This model is fundamentally unsuitable for more complex geometries, however, and extension to two- and three-dimensions is necessary. This interim report summarizes our progress since the previous interim report toward development of a ``finite volume`` model for FCVI.

  4. Chemical and microstructural characterization of thermally grown alumina scales

    SciTech Connect

    Natesan, K.; Richier, C.; Veal, B.W.

    1995-09-01

    An experimental program has been initiated to evaluate the chemical, microstructural, and mechanical integrity of thermally grown oxide scales to establish requirements for improved corrosion performance in terms of composition, structure, and properties. Iron aluminides of several compositions were selected for the study. Oxidation studies were conducted in air and oxygen environments at 1000{degrees}C. The results showed that the scaling kinetics followed a parabolic rate law but that the rates in early stages of oxidation were significantly greater than in later stages; the difference could be attributed to the presence of fast-growing transient iron oxides in the layer during the early stages. Further, scale failure occurred via gross spallation, scale cracking, and nodule formation and was influenced by alloy composition. Auger electron spectroscopy of Ar-exposed specimens of ternary Fe-Cr-Al alloy showed sulfur on the gas/scale side of the interface; the sulfur decreased as the exposure time increased. Raman spectroscopy and ruby fluorescence were used to examine the scale development as a function of oxidation temperature. Ruby-line shift is used to examine phase transformations in alumina and to calculate compressive strains in thermally grown scales.

  5. Inactivation of Lactobacillus helveticus bacteriophages by thermal and chemical treatments.

    PubMed

    Quiberoni, A; Suárez, V B; Reinheimer, J A

    1999-08-01

    The effect of several biocides and thermal treatments on the viability of four Lactobacillus helveticus phages was investigated. Times to achieve 99% inactivation of phages at 63 degrees C and 72 degrees C in three suspension media were calculated. The three suspension media were tris magnesium gelatin buffer (10 mM Tris-HCl, 10 mM MgSO4, and 0.1% wt/vol gelatin), reconstituted skim milk sterile reconstituted commercial nonfat dry skim milk, and Man Rogosa Sharpe broth. The thermal resistance depended on the phage considered, but a treatment of 5 min at 90 degrees C produced a total inactivation of high titer suspensions of all phages studied. The results obtained for the three tested media did not allow us to establish a clear difference among them, since some phages were more heat resistant in Man Rogosa Sharpe broth and others in tris magnesium gelatin buffer. From the investigation on biocides, we established that sodium hypochlorite at a concentration of 100 ppm was very effective in inactivating phages. The suitability of ethanol 75%, commonly used to disinfect utensils and laboratory equipment, was confirmed. Isopropanol turned out to be, in general, less effective than ethanol at the assayed concentrations. In contrast, peracetic acid (0.15%) was found to be an effective biocide for the complete inactivation of all phages studied after 5 min of exposure. The results allowed us to establish a basis for adopting the most effective thermal and chemical treatments for inactivating phages in dairy plant and laboratory environments.

  6. Scientific Basis for a Coupled Thermal-Hydrological-Mechanical-Chemical-Biological Experimental Facility at DUSEL Homestake

    NASA Astrophysics Data System (ADS)

    Sonnenthal, E. L.; Elsworth, D.; Lowell, R. P.; Maher, K.; Mailloux, B. J.; Uzunlar, N.; Freifeld, B. M.; Keimowitz, A. R.; Wang, J. S.

    2009-12-01

    Most natural and engineered earth system processes involve strong coupling of thermal, mechanical, chemical, and sometimes biological processes in rocks that are heterogeneous at a wide range of spatial scales. One of the most pervasive processes in the Earth’s crust is that of fluids (primarily water, but also CO2, hydrocarbons, volcanic gases, etc.) flowing through fractured heated rock under stress. A preliminary design is being formulated for a large-scale subsurface experimental facility to investigate coupled Thermal-Hydrological-Mechanical-Chemical-Biological (THMCB) processes in fractured rock at depth. The experiment would be part of the proposed Deep Underground Science and Engineering Laboratory (DUSEL) in the Homestake Mine, South Dakota. Fundamental geochemical, isotopic, microbiological, laboratory THMC experiments, and numerical modeling will be used to guide the experimental design and evaluation of the time and spatial scales of the coupled THMCB processes. Although we sometimes analyze rocks and fluids for physical and chemical properties, it is difficult to create quantitative numerical models based on fundamental physics and chemistry that can capture the dynamic changes that have occurred or may yet take place. Initial conditions and history are only known roughly at best, and the boundary conditions have likely varied over time as well. Processes such as multicomponent chemical and thermal diffusion, multiphase flow, advection, and thermal expansion/contraction, are taking place simultaneously in rocks that are structurally and chemically complex—heterogeneous assemblages of mineral grains, pores, and fractures—and visually opaque. The only way to fully understand such processes is to carry out well-controlled experiments at a range of scales (grain/pore-scale to decimeter-scale) that can be interrogated and modeled. The THMCB experimental facility is also intended to be a unique laboratory for testing hypotheses regarding effects of

  7. Rapid visualization and large-scale profiling of bacterial lipoproteins with chemical reporters

    PubMed Central

    Rangan, Kavita J.; Yang, Yu-Ying; Charron, Guillaume; Hang, Howard C.

    2011-01-01

    Lipoproteins are a largely uncharacterized class of proteins in bacteria. In this study, metabolic labeling of bacteria with fatty acid chemical reporters allowed rapid profiling of lipid-modified proteins. We identified many candidate lipoproteins in Escherichia coli and detected a novel modification on YjgF. This chemical approach should facilitate future characterization of lipoproteins. PMID:20230003

  8. Rapid computation of chemical equilibrium composition - An application to hydrocarbon combustion

    NASA Technical Reports Server (NTRS)

    Erickson, W. D.; Prabhu, R. K.

    1986-01-01

    A scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free-energy minimization method. The general approach also has application to many other chemical systems.

  9. Examining rapid onset drought development using the thermal infrared based evaporative stress index

    USDA-ARS?s Scientific Manuscript database

    Reliable indicators of rapid drought onset are necessary to improve the utility of drought early warning systems. In this study, the Evaporative Stress Index (ESI), which uses remotely-sensed thermal infrared imagery to estimate evapotranspiration (ET), is compared to meteorological data and United...

  10. Rapid, facile microwave-assisted synthesis of xanthan gum grafted polyaniline for chemical sensor.

    PubMed

    Pandey, Sadanand; Ramontja, James

    2016-08-01

    Grafting method, through microwave radiation procedure is extremely productive in terms of time consumption, cost effectiveness and environmental friendliness. In this study, conductive and thermally stable composite (mwXG-g-PANi) was synthesized by grafting of aniline (ANi) on to xanthan gum (XG) using catalytic weight of initiator, ammonium peroxydisulfate in the process of microwave irradiation in an aqueous medium. The synthesis of mwXG-g-PANi were confirm by FTIR, XRD, TGA, and SEM. The influence of altering the microwave power, exposure time of microwave, concentration of monomer and the amount of initiator of graft polymerization were studied over the grafting parameters, for example, grafting percentage (%G) and grafting efficiency (%E). The maximum %G and %E achieved was 172 and 74.13 respectively. The outcome demonstrates that the microwave irradiation strategy can increase the reaction rate by 72 times over the conventional method. Electrical conductivity of XG and mwXG-g-PANi composite film was performed. The fabricated grafted sample film were then examined for the chemical sensor. The mwXG-g-PANi, effectively integrated and handled, are NH3 sensitive and exhibit a rapid sensing in presence of NH3 vapor. Chemiresistive NH3 sensors with superior room temperature sensing performance were produced with sensor response of 905 at 1ppb and 90% recovery within few second.

  11. Rapid screening of pharmaceutical drugs using thermal desorption - SALDI mass spectrometry

    NASA Astrophysics Data System (ADS)

    Grechnikov, A. A.; Kubasov, A. E.; Georgieva, V. B.; Borodkov, A. S.; Nikiforov, S. M.; Simanovsky, Ya O.; Alimpiev, S. S.

    2012-12-01

    A novel approach to the rapid screening of pharmaceutical drugs by surface assisted laser desorption-ionization (SALDI) mass spectrometry with the rotating ball interface coupled with temperature programmed thermal desorption has been developed. Analytes were thermally desorbed and deposited onto the surface of amorphous silicon substrate attached to the rotating ball. The ball was rotated and the deposited analytes were analyzed using SALDI. The effectiveness of coupling SALDI mass spectrometry with thermal desorption was evaluated by the direct and rapid analysis of tablets containing lidocaine, diphenhydramine and propranolol without any sample pretreatment. The overall duration of the screening procedure was 30÷40 sec. Real urine samples were studied for drug analysis. It is shown that with simple preparation steps, urine samples can be quantitatively analyzed using the proposed technique with the detection limits in the range of 0.2÷0.5 ng/ml.

  12. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  13. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  14. Surface state of GaN after rapid-thermal-annealing using AlN cap-layer

    NASA Astrophysics Data System (ADS)

    El-Zammar, G.; Khalfaoui, W.; Oheix, T.; Yvon, A.; Collard, E.; Cayrel, F.; Alquier, D.

    2015-11-01

    Critical issues need to be overcome to produce high performance Schottky diodes on gallium nitride (GaN). To activate dopant, high temperature thermal treatments are required but damage GaN surface where hexagonal pits appear and prevent any device processing. In this paper, we investigated the efficiency of cap-layers on GaN during thermal treatments to avoid degradation. Aluminum nitride (AlN) and silicon oxide (SiOx) were grown on GaN by direct current reactive magnetron sputtering and plasma-enhanced chemical vapor deposition, respectively. AlN growth parameters were studied to understand their effect on the grown layers and their protection efficiency. Focused ion beam was used to measure AlN layer thickness. Crystalline quality and exact composition were verified using X-ray diffraction and energy dispersive X-ray spectroscopy. Two types of rapid thermal annealing at high temperatures were investigated. Surface roughness and pits density were evaluated using atomic force microscopy and scanning electron microscopy. Cap-layers wet etching was processed in H3PO4 at 120 °C for AlN and in HF (10%) for SiOx. This work reveals effective protection of GaN during thermal treatments at temperatures as high as 1150 °C. Low surface roughness was obtained. Furthermore, no hexagonal pit was observed on the surface.

  15. A hybrid computer program for rapidly solving flowing or static chemical kinetic problems involving many chemical species

    NASA Technical Reports Server (NTRS)

    Mclain, A. G.; Rao, C. S. R.

    1976-01-01

    A hybrid chemical kinetic computer program was assembled which provides a rapid solution to problems involving flowing or static, chemically reacting, gas mixtures. The computer program uses existing subroutines for problem setup, initialization, and preliminary calculations and incorporates a stiff ordinary differential equation solution technique. A number of check cases were recomputed with the hybrid program and the results were almost identical to those previously obtained. The computational time saving was demonstrated with a propane-oxygen-argon shock tube combustion problem involving 31 chemical species and 64 reactions. Information is presented to enable potential users to prepare an input data deck for the calculation of a problem.

  16. Rapid characterization of woody biomass digestibility and chemical composition using near-infrared spectroscopy.

    PubMed

    Hou, Shen; Li, Laigeng

    2011-02-01

    Rapid determination of the properties of lignocellulosic material is highly desirable for biomass production and utilization. In the present study, measurements of woody biomass digestibility and chemical composition using near-infrared reflectance (NIR) spectroscopy were calibrated. Poplar and eucalyptus materials were recorded in NIR spectrum as well as determined for their chemical compositions of Klason lignin, α-cellulose, holocellulose, lignin syringyl/guaiacyl (S/G) ratio and enzymatic digestibility. Fitting of the NIR information with chemical properties and digestibility by partial least-squares (PLS) regression generated a group of trained NIR models that were able to be used for rapid biomass measurement. Applying the models for woody biomass measurements led to a reliable evaluation of the chemical composition and digestibility, suggesting the feasibility of using NIR spectroscopy in the rapid characterization of biomass properties. © 2011 Institute of Botany, Chinese Academy of Sciences.

  17. Method of operating a thermal engine powered by a chemical reaction

    DOEpatents

    Ross, John; Escher, Claus

    1988-01-01

    The invention involves a novel method of increasing the efficiency of a thermal engine. Heat is generated by a non-linear chemical reaction of reactants, said heat being transferred to a thermal engine such as Rankine cycle power plant. The novel method includes externally perturbing one or more of the thermodynamic variables of said non-linear chemical reaction.

  18. Method of operating a thermal engine powered by a chemical reaction

    DOEpatents

    Ross, J.; Escher, C.

    1988-06-07

    The invention involves a novel method of increasing the efficiency of a thermal engine. Heat is generated by a non-linear chemical reaction of reactants, said heat being transferred to a thermal engine such as Rankine cycle power plant. The novel method includes externally perturbing one or more of the thermodynamic variables of said non-linear chemical reaction. 7 figs.

  19. An approximate Riemann solver for thermal and chemical nonequilibrium flows

    NASA Technical Reports Server (NTRS)

    Prabhu, Ramadas K.

    1994-01-01

    Among the many methods available for the determination of inviscid fluxes across a surface of discontinuity, the flux-difference-splitting technique that employs Roe-averaged variables has been used extensively by the CFD community because of its simplicity and its ability to capture shocks exactly. This method, originally developed for perfect gas flows, has since been extended to equilibrium as well as nonequilibrium flows. Determination of the Roe-averaged variables for the case of a perfect gas flow is a simple task; however, for thermal and chemical nonequilibrium flows, some of the variables are not uniquely defined. Methods available in the literature to determine these variables seem to lack sound bases. The present paper describes a simple, yet accurate, method to determine all the variables for nonequilibrium flows in the Roe-average state. The basis for this method is the requirement that the Roe-averaged variables form a consistent set of thermodynamic variables. The present method satisfies the requirement that the square of the speed of sound be positive.

  20. Effects of Variable Thermal Conductivity and Non-linear Thermal Radiation Past an Eyring Powell Nanofluid Flow with Chemical Reaction

    NASA Astrophysics Data System (ADS)

    Ramzan, M.; Bilal, M.; Kanwal, Shamsa; Chung, Jae Dong

    2017-06-01

    Present analysis discusses the boundary layer flow of Eyring Powell nanofluid past a constantly moving surface under the influence of nonlinear thermal radiation. Heat and mass transfer mechanisms are examined under the physically suitable convective boundary condition. Effects of variable thermal conductivity and chemical reaction are also considered. Series solutions of all involved distributions using Homotopy Analysis method (HAM) are obtained. Impacts of dominating embedded flow parameters are discussed through graphical illustrations. It is observed that thermal radiation parameter shows increasing tendency in relation to temperature profile. However, chemical reaction parameter exhibits decreasing behavior versus concentration distribution. Supported by the World Class 300 Project (No. S2367878) of the SMBA (Korea)

  1. A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand.

    PubMed

    Yao, Na; Liu, Zhuan; Chen, Ying; Zhou, Yikai; Xie, Bin

    2015-08-19

    A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5-7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5-1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method.

  2. Rapid Inverse Method to Measure Thermal Diffusivity of Low-Moisture Foods.

    PubMed

    Muramatsu, Yoshiki; Greiby, Ibrahim; Mishra, Dharmendra K; Dolan, Kirk D

    2017-02-01

    Thermal diffusivity is an important transport property needed in modeling and computations of transient heat transfer in basic food processing operations. In addition, the prediction of nutritional and microbial changes occurring in food during thermal processing requires knowledge of thermal diffusivity of foods. The objectives of this study were to develop a new nonisothermal and nonlinear determination method of thermal diffusivity and to measure the thermal diffusivity of low-moisture foods using that new method. Thermal diffusivities of 5 kinds of low-moisture foods (almond meal, corn meal, wheat flour, chocolate fudge, and peanut butter) were estimated using an inverse technique. Samples were canned and heated at the surface in a water bath at about 70 °C. The 1-dimensional transient heat conduction problem for radial coordinates was solved with a finite-difference model. The thermal diffusivity of each of the 5 samples was determined by the ordinary least squares and sequential estimation methods, respectively. Predicted and observed temperature matched well, with maximum residuals of 0.9 °C. The thermal diffusivity values of the samples ranged from 9.8 × 10(-8) to 1.3 × 10(-7) m(2) /s. The advantages of this method are that the device and the estimation method are simple, inexpensive, rapid, and can handle large spatial temperature gradients, such as those experienced during heating of low-moisture foods. The results obtained in this study will be useful in the design of equipment and in calculations for the thermal processing of low-moisture foods. © 2017 Institute of Food Technologists®.

  3. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-05-13

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  4. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2002-01-01

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  5. Fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing

    DOEpatents

    Bates, John B.

    2003-04-29

    Systems and methods are described for fabrication of highly textured lithium cobalt oxide films by rapid thermal annealing. A method of forming a lithium cobalt oxide film includes depositing a film of lithium cobalt oxide on a substrate; rapidly heating the film of lithium cobalt oxide to a target temperature; and maintaining the film of lithium cobalt oxide at the target temperature for a target annealing time of at most, approximately 60 minutes. The systems and methods provide advantages because they require less time to implement and are, therefore less costly than previous techniques.

  6. Rapid sintering of silicon nitride foams decorated with one-dimensional nanostructures by intense thermal radiation

    NASA Astrophysics Data System (ADS)

    Li, Duan; Guzi de Moraes, Elisângela; Guo, Peng; Zou, Ji; Zhang, Junzhan; Colombo, Paolo; Shen, Zhijian

    2014-08-01

    Silicon nitride foams were prepared by direct foaming and subsequent rapid sintering at 1600 °C. The intense thermal radiation generated under the pressureless spark plasma sintering condition facilitated necking of Si3N4 grains. The prepared foams possessed a porosity of ˜80 vol% and a compressive strength of ˜10 MPa, which required only ˜30 min for the entire sintering processes. Rapid growth of one-dimensional SiC nanowires from the cell walls was also observed. Thermodynamic calculations indicated that the vapor-liquid-solid model is applicable to the formation of SiC nanowires under vacuum.

  7. Rapid sintering of silicon nitride foams decorated with one-dimensional nanostructures by intense thermal radiation.

    PubMed

    Li, Duan; Guzi de Moraes, Elisângela; Guo, Peng; Zou, Ji; Zhang, Junzhan; Colombo, Paolo; Shen, Zhijian

    2014-08-01

    Silicon nitride foams were prepared by direct foaming and subsequent rapid sintering at 1600 °C. The intense thermal radiation generated under the pressureless spark plasma sintering condition facilitated necking of Si3N4 grains. The prepared foams possessed a porosity of ∼80 vol% and a compressive strength of ∼10 MPa, which required only ∼30 min for the entire sintering processes. Rapid growth of one-dimensional SiC nanowires from the cell walls was also observed. Thermodynamic calculations indicated that the vapor-liquid-solid model is applicable to the formation of SiC nanowires under vacuum.

  8. Chemical Changes in Proteins Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Dutson, T. R.; Orcutt, M. W.

    1984-01-01

    Discusses effects of thermal processing on proteins, focusing on (1) the Maillard reaction; (2) heat denaturation of proteins; (3) aggregation, precipitation, gelation, and degradation; and (4) other thermally induced protein reactions. Also discusses effects of thermal processing on muscle foods, egg proteins, fruits and vegetables, and cereal…

  9. Chemical Changes in Proteins Produced by Thermal Processing.

    ERIC Educational Resources Information Center

    Dutson, T. R.; Orcutt, M. W.

    1984-01-01

    Discusses effects of thermal processing on proteins, focusing on (1) the Maillard reaction; (2) heat denaturation of proteins; (3) aggregation, precipitation, gelation, and degradation; and (4) other thermally induced protein reactions. Also discusses effects of thermal processing on muscle foods, egg proteins, fruits and vegetables, and cereal…

  10. Multicycle rapid thermal annealing optimization of Mg-implanted GaN: Evolution of surface, optical, and structural properties

    NASA Astrophysics Data System (ADS)

    Greenlee, Jordan D.; Feigelson, Boris N.; Anderson, Travis J.; Tadjer, Marko J.; Hite, Jennifer K.; Mastro, Michael A.; Eddy, Charles R.; Hobart, Karl D.; Kub, Francis J.

    2014-08-01

    The first step of a multi-cycle rapid thermal annealing process was systematically studied. The surface, structure, and optical properties of Mg implanted GaN thin films annealed at temperatures ranging from 900 to 1200 °C were investigated by Raman spectroscopy, photoluminescence, UV-visible spectroscopy, atomic force microscopy, and Nomarski microscopy. The GaN thin films are capped with two layers of in-situ metal organic chemical vapor deposition -grown AlN and annealed in 24 bar of N2 overpressure to avoid GaN decomposition. The crystal quality of the GaN improves with increasing annealing temperature as confirmed by UV-visible spectroscopy and the full widths at half maximums of the E2 and A1 (LO) Raman modes. The crystal quality of films annealed above 1100 °C exceeds the quality of the as-grown films. At 1200 °C, Mg is optically activated, which is determined by photoluminescence measurements. However, at 1200 °C, the GaN begins to decompose as evidenced by pit formation on the surface of the samples. Therefore, it was determined that the optimal temperature for the first step in a multi-cycle rapid thermal anneal process should be conducted at 1150 °C due to crystal quality and surface morphology considerations.

  11. Multicycle rapid thermal annealing optimization of Mg-implanted GaN: Evolution of surface, optical, and structural properties

    SciTech Connect

    Greenlee, Jordan D.; Feigelson, Boris N.; Anderson, Travis J.; Hite, Jennifer K.; Mastro, Michael A.; Eddy, Charles R.; Hobart, Karl D.; Kub, Francis J.; Tadjer, Marko J.

    2014-08-14

    The first step of a multi-cycle rapid thermal annealing process was systematically studied. The surface, structure, and optical properties of Mg implanted GaN thin films annealed at temperatures ranging from 900 to 1200 °C were investigated by Raman spectroscopy, photoluminescence, UV-visible spectroscopy, atomic force microscopy, and Nomarski microscopy. The GaN thin films are capped with two layers of in-situ metal organic chemical vapor deposition -grown AlN and annealed in 24 bar of N{sub 2} overpressure to avoid GaN decomposition. The crystal quality of the GaN improves with increasing annealing temperature as confirmed by UV-visible spectroscopy and the full widths at half maximums of the E{sub 2} and A{sub 1} (LO) Raman modes. The crystal quality of films annealed above 1100 °C exceeds the quality of the as-grown films. At 1200 °C, Mg is optically activated, which is determined by photoluminescence measurements. However, at 1200 °C, the GaN begins to decompose as evidenced by pit formation on the surface of the samples. Therefore, it was determined that the optimal temperature for the first step in a multi-cycle rapid thermal anneal process should be conducted at 1150 °C due to crystal quality and surface morphology considerations.

  12. Conversion of concentrated solar thermal energy into chemical energy.

    PubMed

    Tamaura, Yutaka

    2012-01-01

    When a concentrated solar beam is irradiated to the ceramics such as Ni-ferrite, the high-energy flux in the range of 1500-2500 kW/m(2) is absorbed by an excess Frenkel defect formation. This non-equilibrium state defect is generated not by heating at a low heating-rate (30 K/min), but by irradiating high flux energy of concentrated solar beam rapidly at a high heating rate (200 K/min). The defect can be spontaneously converted to chemical energy of a cation-excess spinel structure (reduced-oxide form) at the temperature around 1773 K. Thus, the O(2) releasing reaction (α-O(2) releasing reaction) proceeds in two-steps; (1) high flux energy of concentrated solar beam absorption by formation of the non-equilibrium Frenkel defect and (2) the O(2) gas formation from the O(2-) in the Frenkel defect even in air atmosphere. The 2nd step proceeds without the solar radiation. We may say that the 1st step is light reaction, and 2nd step, dark reaction, just like in photosynthesis process.

  13. Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

    SciTech Connect

    Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.; Burst, James M.; Reese, Matthew O.; Wolden, C. A.; Gessert, Timothy A.; Metzger, Wyatt K.; Garner, S.; Barnes, Teresa M.

    2015-06-14

    Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the device performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.

  14. Evolution of nano-structures of silver due to rapid thermal annealing

    SciTech Connect

    Mondal, Shyamal Bhattacharyya, S. R.

    2014-04-24

    This report deals with rapid thermal annealing (RTA) effect on continuous silver film on Si(100) substrate. For this purpose silver films of different thicknesses were deposited and subsequently annealed at 500 and 800 °C. The as-deposited and annealed samples were investigated by scanning electron microscope (SEM). Formations of different nano-structures have been observed. Fragmentation of formed nanoislands also observed at temperature below melting temperature.

  15. Rapid thermal cycling of solar array blanket coupons for Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Scheiman, David A.; Smith, Bryan K.

    1991-01-01

    The NASA Lewis Research Center has been conducting rapid thermal cycling on blanket coupons for Space Station Freedom. This testing includes two designs (8 coupons total) of the solar array. Four coupons were fabricated as part of the Photovoltaic Array Environmental Protection Program (PAEP), NAS3-25079, at Lockheed Missiles and Space Company. These coupons began cycling in early 1989 and have completed 172,000 thermal cycles. Four other coupons were fabricated a year later and included several design changes; cycling of these began in early 1990 and has reached 90,000 cycles. The objective of this testing is to demonstrate the durability or operational lifetime (15 yrs.) of the welded interconnects within a low earth orbit (LEO) thermal cycling environment. The blanket coupons, design changes, test description, status to date including performance and observed anomalies, and any insights related to the testing of these coupons are described. The description of a third design is included.

  16. Advanced deposition model for thermal activated chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Cai, Dang

    Thermal Activated Chemical Vapor Deposition (TACVD) is defined as the formation of a stable solid product on a heated substrate surface from chemical reactions and/or dissociation of gaseous reactants in an activated environment. It has become an essential process for producing solid film, bulk material, coating, fibers, powders and monolithic components. Global market of CVD products has reached multi billions dollars for each year. In the recent years CVD process has been extensively used to manufacture semiconductors and other electronic components such as polysilicon, AlN and GaN. Extensive research effort has been directed to improve deposition quality and throughput. To obtain fast and high quality deposition, operational conditions such as temperature, pressure, fluid velocity and species concentration and geometry conditions such as source-substrate distance need to be well controlled in a CVD system. This thesis will focus on design of CVD processes through understanding the transport and reaction phenomena in the growth reactor. Since the in situ monitor is almost impossible for CVD reactor, many industrial resources have been expended to determine the optimum design by semi-empirical methods and trial-and-error procedures. This approach has allowed the achievement of improvements in the deposition sequence, but begins to show its limitations, as this method cannot always fulfill the more and more stringent specifications of the industry. To resolve this problem, numerical simulation is widely used in studying the growth techniques. The difficulty of numerical simulation of TACVD crystal growth process lies in the simulation of gas phase and surface reactions, especially the latter one, due to the fact that very limited kinetic information is available in the open literature. In this thesis, an advanced deposition model was developed to study the multi-component fluid flow, homogeneous gas phase reactions inside the reactor chamber, heterogeneous surface

  17. Thermal and chemical evolution of The Geysers geothermal system, California

    SciTech Connect

    Moore, J.N.

    1992-01-01

    Fluid inclusions and mineral assemblages provide a reward of the thermal and chemical changes that occurred during the evolution of The Geysers geothermal system. The data document the presence of an extensive liquid dominated geothermal system that developed in response to felsite intrusion and its evolution to a vapor-dominated regime. Temperatures within the early liquid-dominated system ranged from 175 C at a distance of 7200 feet from the felsite to more than 350 C near the contact while salinities varied from 5 equivalent weight percent NaCl (at a distance of 5500 feet) to more than 26 weight percent NaCl. As temperatures around the felsite declined, the liquid-dominated system collapsed upon itself. Downward migration of the low salinity waters resulted in dilution of the fluids present in regions now occupied by the caprock and normal vapor-dominated reservoir. In contrast, dilution was minor in rocks now hosting the high-temperature vapor-dominated reservoir. This suggests that low permeabilities are the primary reason for the development of the high-temperature reservoir. Boiling within the caprock produced late-stage veins of calcite and quartz. As the fluid boiled off, condensate was trapped as low salinity fluid inclusions. Within the main body of the reservoir, a liquid phase with salinities of up to 7 equivalent weight percent NaCl persisted to temperatures between 250 and 270 C. However, except for the presence of vapor-rich inclusions, little evidence of boiling within the reservoir rocks was preserved.

  18. Leaf thermal and hydraulic capacitances - structural safeguards for rapid ambient fluctuations

    NASA Astrophysics Data System (ADS)

    Schymanski, S. J.; Or, D.; Zwieniecki, M.

    2011-12-01

    Leaves may be subjected to rapidly fluctuating irradiation or thermal conditions due to motion of sun flecks and clouds or passage of warm and dry wind gusts. Given a stomatal characteristic time scale (~5 min) for adjusting transpiration flux, fluctuations of environmental conditions at shorter time scales (~1 min) could push leaf hydraulic and thermal status beyond its operational limits resulting in xylem cavitation or overheating. As active stomatal protection may not be adequate, we propose that leaf thermal and hydraulic capacitances and hence leaf specific mass (hydrated thickness) provide passive protection and play a critical role for autonomous and intrinsic capacitive-based responses to rapid fluctuations. For example, a simple variable leaf mass per unit area can affect both thermal and hydraulic capacitances. Thus a thin leaf (0.2 mm) exposed to a sunfleck can experience an increase in leaf temperature by 20K in the order of 3 minutes, i.e. before stomata can activate evaporative cooling. Increasing leaf thickness can be an effective measure to increase the buffer for such environmental fluctuations, so that slower regulatory measures such as stomatal adjustments can take over before detrimental effects take place. Systematic measurements of thermal changes in response to step changes in radiation conditions were obtained using laser illumination and infra-red thermal imaging of leaf laser-illuminated area across a wide range of leaf morphologies from major plant divisions (ferns, gymnosperms and angiosperms). Results confirm inverse relationships between leaf thickness and temperature rise (measured as steady state temperature increase). Hydraulic impacts of such structural capacitance on xylem function will be discussed.

  19. Rapid analysis of animal drug residues by microcolumn solid-phase extraction and thermal desorption-ion trap mass spectrometry

    SciTech Connect

    Barshick, S.A.; Buchanan, M.V.

    1994-11-01

    A new approach was developed for the rapid and quantitative determination of an anthelmintic drug, phenothiazine, in milk. The technique involves a simple extraction procedure using a C{sub 18} microcolumn disc, followed by thermal desorption of the analyte from the disc directly into an ion trap mass spectrometer. The compounds are selectively ionized by isobutane chemical ionization and detected by tandem mass spectrometry. With this approach, 10 ppb detection limits were achieved with as little as 100 {mu}L mild and only 10 min of analysis time. This approach was used to analyze samples of milk taken from a cow administered a one-time therapeutic dose of phenothiazine. The target compound could be detected at 56 post-dosage, corresponding to a concentration of 30 ppb. 13 refs., 3 figs., 2 tabs.

  20. Effect of rapid thermal annealing on Ti AlN interfaces

    NASA Astrophysics Data System (ADS)

    Wang, Youxiang; Chen, Xin

    1999-07-01

    The interface diffusion, reaction, and adherence of rapid thermal annealed Ti/ALN were investigated by RBS, AES, SIMS, XRD and a scratch test. The experimental results show that diffusion and reaction occurs at the interface of Ti/AlN when the sample is rapidly annealed. During annealing, both the O adsorbed on the surface and doped in the AlN substrate diffuse into the Ti film. At low temperature TiO 2 is produced. At higher temperature O reacts with the diffused Al in the Ti film and produces an Al 2O 3 layer in the middle of the film. N diffuses into the Ti film and produces TiN with an interface reaction. Ti oxide is produced at the interface between the film and the substrate. Scratch test results show that interface adherence is distinctly improved by rapid annealing at low temperature and decreases at higher temperature.

  1. A rapid method for the computation of equilibrium chemical composition of air to 15000 K

    NASA Technical Reports Server (NTRS)

    Prabhu, Ramadas K.; Erickson, Wayne D.

    1988-01-01

    A rapid computational method has been developed to determine the chemical composition of equilibrium air to 15000 K. Eleven chemically reacting species, i.e., O2, N2, O, NO, N, NO+, e-, N+, O+, Ar, and Ar+ are included. The method involves combining algebraically seven nonlinear equilibrium equations and four linear elemental mass balance and charge neutrality equations. Computational speeds for determining the equilibrium chemical composition are significantly faster than the often used free energy minimization procedure. Data are also included from which the thermodynamic properties of air can be computed. A listing of the computer program together with a set of sample results are included.

  2. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    NASA Astrophysics Data System (ADS)

    Brumfield, B. E.; Taubman, M. S.; Phillips, M. C.

    2016-02-01

    A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at an update rate of 40 Hz (25 ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Based on a noise equivalent concentration analysis of the current system, detection limits of 147.0 ppbv and 151.6 ppbv in a 25 ms measurement time are estimated for D2O and HDO respectively with a 127 m optical path. These detection limits are reduced to 23.0 and 24.0 ppbv with a 1 s averaging time for D2O and HDO respectively. Detection limits < 200 ppbv are also estimated for N2O, F134A, CH4, Acetone, and SO2 for a 25 ms measurement time.

  3. A Rapid and Low-Cost PCR Thermal Cycler for Low Resource Settings.

    PubMed

    Wong, Grace; Wong, Isaac; Chan, Kamfai; Hsieh, Yicheng; Wong, Season

    2015-01-01

    Many modern molecular diagnostic assays targeting nucleic acids are typically confined to developed countries or to the national reference laboratories of developing-world countries. The ability to make technologies for the rapid diagnosis of infectious diseases broadly available in a portable, low-cost format would mark a revolutionary step forward in global health. Many molecular assays are also developed based on polymerase chain reactions (PCR), which require thermal cyclers that are relatively heavy (>20 pounds) and need continuous electrical power. The temperature ramping speed of most economical thermal cyclers are relatively slow (2 to 3 °C/s) so a polymerase chain reaction can take 1 to 2 hours. Most of all, these thermal cyclers are still too expensive ($2k to $4k) for low-resource setting uses. In this article, we demonstrate the development of a low-cost and rapid water bath based thermal cycler that does not require active temperature control or continuous power supply during PCR. This unit costs $130 to build using commercial off-the-shelf items. The use of two or three vacuum-insulated stainless-steel Thermos food jars containing heated water (for denaturation and annealing/extension steps) and a layer of oil on top of the water allow for significantly stabilized temperatures for PCR to take place. Using an Arduino-based microcontroller, we automate the "archaic" method of hand-transferring PCR tubes between water baths. We demonstrate that this innovative unit can deliver high speed PCR (17 s per PCR cycle) with the potential to go beyond the 1,522 bp long amplicons tested in this study and can amplify from templates down to at least 20 copies per reaction. The unit also accepts regular PCR tubes and glass capillary tubes. The PCR efficiency of our thermal cycler is not different from other commercial thermal cyclers. When combined with a rapid nucleic acid detection approach, the thermos thermal cycler (TTC) can enable on-site molecular

  4. A Rapid and Low-Cost PCR Thermal Cycler for Low Resource Settings

    PubMed Central

    Wong, Grace; Wong, Isaac; Chan, Kamfai; Hsieh, Yicheng; Wong, Season

    2015-01-01

    Background Many modern molecular diagnostic assays targeting nucleic acids are typically confined to developed countries or to the national reference laboratories of developing-world countries. The ability to make technologies for the rapid diagnosis of infectious diseases broadly available in a portable, low-cost format would mark a revolutionary step forward in global health. Many molecular assays are also developed based on polymerase chain reactions (PCR), which require thermal cyclers that are relatively heavy (>20 pounds) and need continuous electrical power. The temperature ramping speed of most economical thermal cyclers are relatively slow (2 to 3°C/s) so a polymerase chain reaction can take 1 to 2 hours. Most of all, these thermal cyclers are still too expensive ($2k to $4k) for low-resource setting uses. Methodology/Principal Findings In this article, we demonstrate the development of a low-cost and rapid water bath based thermal cycler that does not require active temperature control or continuous power supply during PCR. This unit costs $130 to build using commercial off-the-shelf items. The use of two or three vacuum-insulated stainless-steel Thermos food jars containing heated water (for denaturation and annealing/extension steps) and a layer of oil on top of the water allow for significantly stabilized temperatures for PCR to take place. Using an Arduino-based microcontroller, we automate the “archaic” method of hand-transferring PCR tubes between water baths. Conclusions/Significance We demonstrate that this innovative unit can deliver high speed PCR (17 s per PCR cycle) with the potential to go beyond the 1,522 bp long amplicons tested in this study and can amplify from templates down to at least 20 copies per reaction. The unit also accepts regular PCR tubes and glass capillary tubes. The PCR efficiency of our thermal cycler is not different from other commercial thermal cyclers. When combined with a rapid nucleic acid detection approach

  5. RAPID SPATIAL MAPPING OF CHEMICALS DISPERSED ACROSS SURFACES USING AN AUTOSAMPLER/DART/TOFMS

    EPA Science Inventory

    Rapid identification and semi-quantitation of chemicals spatially dispersed and

    deposited on surfaces by accidental, deliberate, or weather-related events requires analysis of

    hundreds of samples, usually obtained by sampling with wipes. Hand-held devices used on-si...

  6. Rapid Semi-Quantitative Surface Mapping of Airborne-Dispersed Chemicals Using Mass Spectrometry

    EPA Science Inventory

    Chemicals can be dispersed accidentally, deliberately, or by weather-related events. Rapid mapping of contaminant distributions is necessary to assess exposure risks and to plan remediation, when needed. Ten pulverized aspirin or NoDozTM tablets containing caffeine wer...

  7. Rapid Semi-Quantitative Surface Mapping of Airborne-Dispersed Chemicals Using Mass Spectrometry

    EPA Science Inventory

    Chemicals can be dispersed accidentally, deliberately, or by weather-related events. Rapid mapping of contaminant distributions is necessary to assess exposure risks and to plan remediation, when needed. Ten pulverized aspirin or NoDozTM tablets containing caffeine wer...

  8. RAPID SPATIAL MAPPING OF CHEMICALS DISPERSED ACROSS SURFACES USING AN AUTOSAMPLER/DART/TOFMS

    EPA Science Inventory

    Rapid identification and semi-quantitation of chemicals spatially dispersed and

    deposited on surfaces by accidental, deliberate, or weather-related events requires analysis of

    hundreds of samples, usually obtained by sampling with wipes. Hand-held devices used on-si...

  9. Chemical Genetics: receptor-ligand pairs for rapid manipulation of neuronal activity

    PubMed Central

    Wulff, Peer; Arenkiel, Benjamin R.

    2012-01-01

    Towards the functional dissection of neuronal circuits, a number of new genetic tools have been developed that enable rapid and reversible manipulation of genetically defined neuronal subtypes in intact mammalian brain circuits. Alongside the breakthrough technology of optogenetics, receptor-ligand pairs provide complementary approaches to modulate neuronal activity using chemical-genetics. PMID:22119143

  10. Hydro-chemical specifications of thermal waters from different geographical regions in Turkey

    NASA Astrophysics Data System (ADS)

    Seker, D. Z.; Aydin, S.; Sivri, N.; Bitik, E.; Cakir, Z.

    2014-12-01

    In many countries thermal springs are utilized for a variety of purposes, such as the generation of power, direct space heating, industrial processes, aquaculture and many more. The optimal use of a thermal spring is largely dependent upon its physical and chemical characteristics. The physical and chemical parameters of groundwater play a significant role in classifying and assessing water quality. Major ions constitute the most significant part of the total dissolved solids present in the groundwater and the concentration of these ions in ground water depends mainly on the hydro chemical processes that place in the aquifer system. This article focuses on the thermal and chemical features of 21 thermal springs located in the overall of the Turkey. Field data and water samples were collected for analysis of physical and chemical parameters. Thermal springs and thermal wells have temperatures ranging from 35 to 95°C. The pH values of the thermal waters change between 6.3 and 9.6. A Piper trilinear diagram and Schoeller diagram show that all the thermal waters are characterized by the dominance of anion-cation. Thermal waters display various chemical compositions and high temperature waters have Na-SO4, Na-HCO3, Na-Cl, Ca-SO4, Ca-HCO3 type. The springs are associated with faults and impermeable dykes and are assumed to be of meteoric origin. The mineral composition of the thermal waters reflects the geological formations found at the depth of origin. All thermal water springs are suitable for use in terms balneology since they contain high levels of mineral content and temperature. At the same time, some samples can be consumed by humans as soda water and mineral water. However, it is important to keep such limitations in mind when determining the ultimate use of the thermal springs.

  11. DEAD ZONES AS THERMAL BARRIERS TO RAPID PLANETARY MIGRATION IN PROTOPLANETARY DISKS

    SciTech Connect

    Hasegawa, Yasuhiro; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2010-02-20

    Planetary migration in standard models of gaseous protoplanetary disks is known to be very rapid ({approx}10{sup 5} years), jeopardizing the existence of planetary systems. We present a new mechanism for significantly slowing rapid planetary migration, discovered by means of radiative transfer calculations of the thermal structure of protoplanetary disks irradiated by their central stars. Rapid dust settling in a disk's dead zone-a region with very little turbulence-leaves a dusty wall at its outer edge. We show that the back-heating of the dead zone by this irradiated wall produces a positive gradient of the disk temperature, which acts as a thermal barrier to planetary migration which persists for the disk lifetime. Although we analyze in detail the migration of a super-Earth in a low-mass disk around an M star, our findings can apply to a wide variety of young planetary systems. We compare our findings with other potentially important stopping mechanisms and show that there are large parameter spaces for which dead zones are likely to play the most important role for reproducing the observed mass-period relation in longer planetary periods.

  12. Effective control of photomask surface chemical residuals through thermal treatment

    NASA Astrophysics Data System (ADS)

    Kang, Han-Byul; Kim, Jong-Min; Kim, Yong-Dae; Cho, Hyun-Joon; Choi, Sang-Soo

    2005-05-01

    We investigated the control of residual ions on the mask surface and the phase/transmission change rate by using thermal treatment after a conventional cleaning process. We hypothesized that the remaining sulfuric ions on the mask surface could combine with other ions and produce compounds during the thermal treatment. These compounds are easily removed by a hot D.I water rinse. Our study shows that the amount of remaining sulfuric ions is 250ng/mask when the mask has been thermally treated. The amount of sulfuric ions is substantially reduced compared to the results of other cleaning processes. Additionally we have found that the thermal treatment can be reduced varying the phase/trans value according to the cleaning cycle and the variation was stable even with a higher concentration of SC-1 solution.

  13. Subcritical Thermal Convection of Liquid Metals in a Rapidly Rotating Sphere

    NASA Astrophysics Data System (ADS)

    Kaplan, E. J.; Schaeffer, N.; Vidal, J.; Cardin, P.

    2017-09-01

    Planetary cores consist of liquid metals (low Prandtl number Pr) that convect as the core cools. Here, we study nonlinear convection in a rotating (low Ekman number Ek) planetary core using a fully 3D direct numerical simulation. Near the critical thermal forcing (Rayleigh number Ra), convection onsets as thermal Rossby waves, but as Ra increases, this state is superseded by one dominated by advection. At moderate rotation, these states (here called the weak branch and strong branch, respectively) are smoothly connected. As the planetary core rotates faster, the smooth transition is replaced by hysteresis cycles and subcriticality until the weak branch disappears entirely and the strong branch onsets in a turbulent state at Ek <10-6. Here, the strong branch persists even as the thermal forcing drops well below the linear onset of convection (Ra =0.7 Racrit in this study). We highlight the importance of the Reynolds stress, which is required for convection to subsist below the linear onset. In addition, the Péclet number is consistently above 10 in the strong branch. We further note the presence of a strong zonal flow that is nonetheless unimportant to the convective state. Our study suggests that, in the asymptotic regime of rapid rotation relevant for planetary interiors, thermal convection of liquid metals in a sphere onsets through a subcritical bifurcation.

  14. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    NASA Astrophysics Data System (ADS)

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance.

  15. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    PubMed Central

    Wickman, B.; Bastos Fanta, A.; Burrows, A.; Hellman, A.; Wagner, J. B.; Iandolo, B.

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance. PMID:28091573

  16. Rapid microplate, green method for high-throughput evaluation of vinegar acidity using thermal infrared enthalpimetry.

    PubMed

    Tischer, Bruna; Oliveira, Alessandra Stangherlin; Ferreira, Daniele de Freitas; Menezes, Cristiano Ragagnin; Duarte, Fábio Andrei; Wagner, Roger; Barin, Juliano Smanioto

    2017-01-15

    Infrared thermal imaging was combined with disposable microplates to perform enthalpimetric analysis using an infrared camera to monitor temperature without contact. The proposed thermal infrared enthalpimetry (TIE) method was used to determine the total, fixed and volatile acidities of vinegars. Sample preparation and analysis were performed in the same vessel, avoiding excessive sample handling and reducing energy expenditure by more than ten times. The results agreed with those of the conventional method for different kinds of vinegars, with values of 1.7%, and 2.3% for repeatability and intermediate precision, respectively. A linear calibration curve was obtained from 0.040 to 1.30molL(-1). The proposed method provided rapid results (within 10s) for four samples simultaneously, a sample throughput of up to 480 samples per hour. In addition, the method complies with at least eight of twelve recommendations for green analytical chemistry, making TIE a promising tool for routine vinegar analysis.

  17. Pt/Ti/n-InP nonalloyed ohmic contacts formed by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Katz, A.; Weir, B. E.; Chu, S. N. G.; Thomas, P. M.; Soler, M.; Boone, T.; Dautremont-Smith, W. C.

    1990-04-01

    Low resistance nonalloyed ohmic contacts of e-gun evaporated Pt/Ti to S doped n-InP 5×1017, 1×1018, and 5×1018 cm-3 have been fabricated by rapid thermal processing. The contacts to the lower doped substrates (5×1017 and 1×1018 cm-3) were rectifying as-deposited as well as after heat treatment at temperatures lower than 350 °C. Higher processing temperatures stimulated the Schottky to ohmic contact conversion with minimum specific contact resistance of 1.5×10-5 and 5×10-6 Ω cm2, respectively, as a result of rapid thermal processing at 450 °C for 30 s. Heating at a temperature of 550 °C again yielded a Schottky contact. The contact to the 5×1018 cm-3 InP was ohmic as deposited with a specific contact resistance value of 1.1×10-4 Ω cm2. Supplying heat treatment to the contact caused a decrease of the specific contact resistance to a minimum of 8×10-7 Ω cm2 as a result of rapid thermal processing at 450 °C for 30 s. In all cases, this heat treatment caused a limited interfacial reactions between the Ti and the InP, and resulted in an almost abrupt interface. Heating at temperatures higher than 500 °C resulted in an interfacial intermixing and a mutual migration and reaction of the Ti and the semiconductor elements. The Pt/Ti bilayer structure was highly tensile as deposited (5×109 dyn cm-2) and became stress-free as a result of the interfacial reactions which took place while heating the samples to temperature of 400 °C or higher.

  18. The application of computational simulation to design optimization of an axisymmetric rapid thermal processing system

    SciTech Connect

    Spence, P.A.; Winters, W.S.; Kee, R.J.; Kermani, A.

    1994-08-01

    We are developing and applying computational models to guide the development of a rapid-thermal-processing system. This work concentrates on scale-up and commercialization of the axisymmetric, multiple-lamp-ring approach that was pioneered by Texas Instruments in the Microelectronics Manufacturing Science and Technology program. CVC Products intends to incorporate the tool into their open-architecture MESC compatible cluster environment. Integration of modeling into the product development process can reduce time-to-market and development costs, as well as improve tool performance.

  19. High carrier activation of Mg ion-implanted GaN by conventional rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Niwa, Takaki; Fujii, Takahiro; Oka, Tohru

    2017-09-01

    A high activation ratio of Mg ion implantation by conventional rapid thermal annealing (RTA) was demonstrated. To obtain the high activation ratio of Mg ion implantation, the dependence of hole concentration on Mg dose was investigated. A maximum hole concentration and a high activation ratio of 2.3% were obtained at a Mg dose of 2.3 × 1014 cm-2 between 9.2 × 1013 and 2.3 × 1015 cm-2. The ratio is, to the best of our knowledge, the highest ever obtained by conventional RTA.

  20. Effect of rapid thermal annealing on the noise properties of InAs/GaAs quantum dot structures

    SciTech Connect

    Arpatzanis, N.; Tsormpatzoglou, A.; Dimitriadis, C. A.; Song, J. D.; Choi, W. J.; Lee, J. I.; Charitidis, C.

    2007-09-01

    Self-assembled InAs quantum dots (QDs) were grown by molecular beam epitaxy (MBE) on n{sup +}-GaAs substrates, capped between 0.4 {mu}m thick n-type GaAs layers with electron concentration of 1x10{sup 16} cm{sup -3}. The effect of rapid thermal annealing at 700 deg. C for 60 s on the noise properties of the structure has been investigated using Au/n-GaAs Schottky diodes as test devices. In the reference sample without containing QDs, the noise spectra show a generation-recombination (g-r) noise behavior due to a discrete energy level located about 0.51 eV below the conduction band edge. This trap is ascribed to the M4 (or EL3) trap in GaAs MBE layers, related to a chemical impurity-native defect complex. In the structure with embedded QDs, the observed g-r noise spectra are due to a midgap trap level ascribed to the EL2 trap in GaAs, which is related to the InAs QDs dissolution due to the thermal treatment.

  1. Effect of rapid thermal annealing on the noise properties of InAs /GaAs quantum dot structures

    NASA Astrophysics Data System (ADS)

    Arpatzanis, N.; Tsormpatzoglou, A.; Dimitriadis, C. A.; Song, J. D.; Choi, W. J.; Lee, J. I.; Charitidis, C.

    2007-09-01

    Self-assembled InAs quantum dots (QDs) were grown by molecular beam epitaxy (MBE) on n+-GaAs substrates, capped between 0.4μm thick n-type GaAs layers with electron concentration of 1×1016cm-3. The effect of rapid thermal annealing at 700°C for 60s on the noise properties of the structure has been investigated using Au /n-GaAs Schottky diodes as test devices. In the reference sample without containing QDs, the noise spectra show a generation-recombination (g-r) noise behavior due to a discrete energy level located about 0.51eV below the conduction band edge. This trap is ascribed to the M4 (or EL3) trap in GaAs MBE layers, related to a chemical impurity-native defect complex. In the structure with embedded QDs, the observed g-r noise spectra are due to a midgap trap level ascribed to the EL2 trap in GaAs, which is related to the InAs QDs dissolution due to the thermal treatment.

  2. Conformal cooling and rapid thermal cycling in injection molding with 3D printed tools

    NASA Astrophysics Data System (ADS)

    Xu, Xiaorong

    Solid Freeform Fabrication processes such as 3D Printing have demonstrated the potential to produce tools with complex internal geometry. This work explores the application of this capability to improved thermal management for injection molding tooling through: (i)cooling lines which are conformal to the mold surface which provide improved uniformity and stability of mold temperature and (ii)tools with low thermal inertia which, in combination with conformal fluid channels allow for rapid heating and cooling of tooling, thereby facilitating isothermal filling of the mold cavity. This work presents a systematic, modular, approach to the design of conformal cooling channels. Recognizing that the cooling is local to the surface of the tool, the tool is divided up into geometric regions and a channel system is designed for each region. Each channel system is itself modeled as composed of cooling elements, typically the region spanned by two channels. Six criteria are applied including; a transient heat transfer condition which dictates a maximum distance from mold surface to cooling channel, considerations of pressure and temperature drop along the flow channel and considerations of strength of the mold. These criteria are treated as constraints and successful designs are sought which define windows bounded by these constraints. The methodology is demonstrated in application to a complex core and cavity for injection molding. In the area of rapid thermal cycling, this work utilizes the design methods for conformal channels for the heating phases and adds analysis of the packing and cooling phases. A design is created which provides thermal isolation and accommodation of cyclic thermal stresses though an array of bendable support columns which support the molding portion of the tool where the heating/cooling channels are contained. Designed elasticity of the tool is used to aid in packing of the polymer during the cooling phase. Methodology for the design of this

  3. Do thermal tolerances and rapid thermal responses contribute to the invasion potential of Bactrocera dorsalis (Diptera: Tephritidae)?

    PubMed

    Pieterse, Welma; Terblanche, John S; Addison, Pia

    2017-04-01

    Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) has shown remarkable range expansion over the past 10years and invaded several new continents including Africa. Here we report results of a detailed assessment of acute high and low temperature survival ability and the plasticity thereof, to test the hypothesis that traits of the thermal niche have contributed to the species' invasion ability. We also assess life-stage-related variation of thermal tolerances to determine potential stage-related environmental sensitivity. The temperatures at which c. 20% of the population survived of B. dorsalis were determined to be -6.5°C and 42.7°C, respectively, when using 2h exposures. Further, four life stages of B. dorsalis (egg, 3rd instar larvae, pupae and adults) were exposed to high and low discriminating temperatures to compare their thermal survival rates. The egg stage was found to be the most resistant life stage to both high and low temperatures, since 44±2.3% survived the low and 60±4.2% survived the high discriminating temperature treatments respectively. Finally, the potential for adult hardening responses to mediate tolerance of extremes was also considered using a diverse range of acute conditions (using 2h exposures to 15°C, 10°C and 5°C and 30°C, 35°C, 37°C and 39°C as hardening temperatures, and some treatments with and without recovery periods between hardening and discriminating temperature treatment). These showed that although some significant hardening responses could be detected in certain treatments (e.g. after exposure to 37°C and 39°C), the magnitude of this plasticity was generally low compared to two other wide-spread and more geographically-range-restricted con-familial species, Ceratitis capitata and C. rosa. In other words, Bactrocera dorsalis adults were unable to rapidly heat- or cold-harden to the same extent as the other Ceratitis species examined to date. These results suggest a narrower thermal niche in B. dorsalis compared

  4. Rapid thermal lysis of cells using silicon-diamond microcantilever heaters.

    PubMed

    Privorotskaya, Natalya; Liu, Yi-Shao; Lee, Jungchul; Zeng, Hongjun; Carlisle, John A; Radadia, Adarsh; Millet, Larry; Bashir, Rashid; King, William P

    2010-05-07

    This paper presents the design and application of microcantilever heaters for biochemical applications. Thermal lysis of biological cells was demonstrated as a specific example. The microcantilever heaters, fabricated from selectively doped single crystal silicon, provide local resistive heating with highly uniform temperature distribution across the cantilevers. Very importantly, the microcantilever heaters were coated with a layer of 100 nm thick electrically insulating ultrananocrystalline diamond (UNCD) layer used for cell immobilization on the cantilever surface. Fibroblast cells or bacterial cells were immobilized on the UNCD/cantilever surfaces and thermal lysis was demonstrated via optical fluorescence microscopy. Upon electrical heating of the cantilever structures to 93 degrees C for 30 seconds, fibroblast cell and nuclear membrane were compromised and the cells were lysed. Over 90% of viable bacteria were also lysed after 15 seconds of heating at 93 degrees C. This work demonstrates the utility of silicon-UNCD heated microcantilevers for rapid cell lysis and forms the basis for other rapid and localized temperature-regulated microbiological experiments in cantilever-based lab on chip applications.

  5. Broadening of the thermal component of the prompt GRB emission due to rapid temperature evolution

    NASA Astrophysics Data System (ADS)

    Bharali, Priya; Sahayanathan, Sunder; Misra, Ranjeev; Boruah, Kalyanee

    2017-08-01

    The observations of the prompt emission of gamma ray bursts (GRB) by GLAST Burst Monitor (GBM), on board Fermi Gamma-ray Space Telescope, suggest the presence of a significant thermal spectral component, whose origin is not well understood. Recently, it has been shown that for long duration GRBs, the spectral width as defined as the logarithm of the ratio of the energies at which the spectrum falls to half its peak value, lie in the range of 0.84-1.3 with a median value of 1.07. Thus, while most of the GRB spectra are found to be too narrow to be explained by synchrotron emission from an electron distribution, they are also significantly broader than a blackbody spectrum whose width should be 0.54. Here, we consider the possibility that an intrinsic thermal spectrum from a fire-ball like model, may be observed to be broadened if the system undergoes a rapid temperature evolution. We construct a toy-model to show that for bursts with durations in the range 5-70 s, the widths of their 1 second time-averaged spectra can be at the most ≲ 0.557. Thus, while rapid temperature variation can broaden the detected spectral shape, the observed median value of ˜ 1.07 requires that there must be significant sub-photospheric emission and/or an anisotropic explosion to explain the broadening for most GRB spectra.

  6. Shock initiated thermal and chemical responses of HMX crystal from ReaxFF molecular dynamics simulation.

    PubMed

    Zhou, Tingting; Song, Huajie; Liu, Yi; Huang, Fenglei

    2014-07-21

    To gain an atomistic-level understanding of the thermal and chemical responses of condensed energetic materials under thermal shock, we developed a thermal shock reactive dynamics (TS-RD) computational protocol using molecular dynamics simulation coupled with ReaxFF force field. β-Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) was selected as a a target explosive due to its wide usage in the military and industry. The results show that a thermal shock initiated by a large temperature gradient between the "hot" region and the "cold" region results in thermal expansion of the particles and induces a thermal-mechanical wave propagating back and forth in the system with an averaged velocity of 3.32 km s(-1). Heat propagating along the direction of thermal shock leads to a temperature increment of the system and thus chemical reaction initiation. Applying a continuum reactive heat conduction model combined with the temperature distribution obtained from the RD simulation, a heat conduction coefficient is derived as 0.80 W m(-1) K(-1). The chemical reaction mechanisms during thermal shock were analyzed, showing that the reaction is triggered by N-NO2 bond breaking followed by HONO elimination and ring fission. The propagation rates of the reaction front and reaction center are obtained to be 0.069 and 0.038 km s(-1), based on the time and spatial distribution of NO2. The pressure effect on the thermal shock was also investigated by employing uniaxial compression before the thermal shock. We find that compression significantly accelerates thermal-mechanical wave propagation and heat conduction, resulting in higher temperature and more excited molecules and thus earlier initiation and faster propagation of chemical reactions.

  7. Large single-domain growth of monolayer WS2 by rapid-cooling chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Li, Chao; Yamaguchi, Yoshiki; Kaneko, Toshiro; Kato, Toshiaki

    2017-07-01

    A novel method for the synthesis of large monolayer and single-crystal tungsten disulfide (WS2) has been developed by introducing a rapid-cooling stage to the conventional chemical vapor deposition (CVD). The maximum size of single-crystal WS2 can be increased up to 320 µm by adjusting the growth parameters during the rapid-cooling CVD. This is one of the largest sizes of single-crystal transition metal dichalcogenides directly grown on an insulating substrate. A theoretical model reveals that the increase in WS2 size can be explained by the enhanced nucleation probability and the growth velocity, caused by the additional precursors supplied during the rapid cooling.

  8. Microbial quality and physical-chemical characteristics of thermal springs.

    PubMed

    Fazlzadeh, Mehdi; Sadeghi, Hadi; Bagheri, Pari; Poureshg, Yusef; Rostami, Roohollah

    2016-04-01

    Microbial quality and physical-chemical properties of recreational spas were surveyed to investigate the health aspect of the spas' water. A total of 195 samples were collected from pools and springs of the spas in five sites from Ardebil Province of Iran. The effects of an independent factor defined as 'condition' and its component sub-factors (i.e., sampling point, location, and sampling date) on microbial quality and physical-chemical properties of the spas were studied by applying path analysis. The influence of physical-chemical properties on microbial quality was also considered. The percentage of samples exceeding the ISIRI (Swimming pool water microbiological specifications (vol 9412), Institute of Standards and Industrial Research of Iran, Tehran, 2007) limits for Staphylococcus (spp.) was up to 55.8 in the springs and 87.8 in the pools, 58.1 and 99.2 for HPC, 90.7 and 97.8 for total coliform and fecal coliform, and 9.3 and 34.4 for Pseudomonas aeruginosa, respectively. There were significant differences between the pools and springs for both physical-chemical properties and microbial quality. From the path analysis, sampling point was the most effective sub-factor of 'condition' on both the physical-chemical properties and microbial quality. Among the physical-chemical properties, water color had the most enhancing or additive influence on microbial pollution, while EC indicated a reducing or subtractive effect.

  9. EFFECTS OF THERMAL TREATMENTS ON THE CHEMICAL REACTIVITY OF TRICHLOROETHYLENE

    EPA Science Inventory

    A series of experiments was completed to investigate abiotic degradation and reaction product formation of trichloroethylene (TCE) when heated. A quartz-tube apparatus was used to study short residence time and high temperature conditions that are thought to occur during thermal ...

  10. EFFECTS OF THERMAL TREATMENTS ON THE CHEMICAL REACTIVITY OF TRICHLOROETHYLENE

    EPA Science Inventory

    A series of experiments was completed to investigate abiotic degradation and reaction product formation of trichloroethylene (TCE) when heated. A quartz-tube apparatus was used to study short residence time and high temperature conditions that are thought to occur during thermal ...

  11. Si(100)-SiO2 interface properties following rapid thermal processing

    NASA Astrophysics Data System (ADS)

    O'Sullivan, B. J.; Hurley, P. K.; Leveugle, C.; Das, J. H.

    2001-04-01

    An experimental examination of the properties of the Si(100)-SiO2 interface measured following rapid thermal processing (RTP) is presented. The interface properties have been examined using high frequency and quasi-static capacitance-voltage (CV) analysis of metal-oxide-silicon (MOS) capacitor structures immediately following either rapid thermal oxidation (RTO) or rapid thermal annealing (RTA). The experimental results reveal a characteristic peak in the CV response measured following dry RTO and RTA (T>800 °C), as the Fermi level at the Si(100)-SiO2 interface approaches the conduction band edge. Analysis of the QSCV responses reveals a high interface state density across the energy gap following dry RTO and RTA processing, with a characteristic peak density in the range 5.5×1012 to 1.7×1013cm-2 eV-1 located at approximately 0.85-0.88 eV above the valence band edge. When the background density of states for a hydrogen-passivated interface is subtracted, another peak of lower density (3×1012 to 7×1012cm-2 eV-1) is observed at approximately 0.25-0.33 eV above the valence band edge. The experimental results point to a common interface state defect present after processes involving rapid cooling (101-102°C/s) from a temperature of 800 °C or above, in a hydrogen free ambient. This work demonstrates that the interface states measured following RTP (T>800 °C) are the net contribution of the Pb0/Pb1 silicon dangling bond defects for the oxidized Si(100) orientation. An important conclusion arising from this work is that the primary effect of an RTA in nitrogen (600-1050 °C) is to cause hydrogen desorption from pre-existing Pb0/Pb1 silicon dangling bond defects. The implications of this work to the study of the Si-SiO2 interface, and the technological implications for silicon based MOS processes, are briefly discussed. The significance of these new results to thin oxide growth and optimization by RTO are also considered.

  12. Galvanic displacement reaction and rapid thermal annealing in size/shape controlling silver nanoparticles on silicon substrate

    NASA Astrophysics Data System (ADS)

    Ghosh, Tapas; Satpati, Biswarup

    2017-05-01

    The effect of the thermal annealing on silver nanoparticles deposited on silicon surface has been studied. The silver nanoparticles have been deposited by the galvanic displacement reaction. Rapid thermal annealing (RTA) has been performed on the Si substrate, containing the silver nanoparticles. The scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) study show that the galvanic displacement reaction and subsequent rapid thermal annealing could lead to well separated and spherical shaped larger silver nanoparticles on silicon substrate.

  13. The Rotary Zone Thermal Cycler: A Low-Power System Enabling Automated Rapid PCR

    PubMed Central

    Bartsch, Michael S.; Renzi, Ronald F.; Van de Vreugde, James L.; Kim, Hanyoup; Knight, Daniel L.; Sinha, Anupama; Branda, Steven S.; Patel, Kamlesh D.

    2015-01-01

    Advances in molecular biology, microfluidics, and laboratory automation continue to expand the accessibility and applicability of these methods beyond the confines of conventional, centralized laboratory facilities and into point of use roles in clinical, military, forensic, and field-deployed applications. As a result, there is a growing need to adapt the unit operations of molecular biology (e.g., aliquoting, centrifuging, mixing, and thermal cycling) to compact, portable, low-power, and automation-ready formats. Here we present one such adaptation, the rotary zone thermal cycler (RZTC), a novel wheel-based device capable of cycling up to four different fixed-temperature blocks into contact with a stationary 4-microliter capillary-bound sample to realize 1-3 second transitions with steady state heater power of less than 10 W. We demonstrate the utility of the RZTC for DNA amplification as part of a highly integrated rotary zone PCR (rzPCR) system that uses low-volume valves and syringe-based fluid handling to automate sample loading and unloading, thermal cycling, and between-run cleaning functionalities in a compact, modular form factor. In addition to characterizing the performance of the RZTC and the efficacy of different online cleaning protocols, we present preliminary results for rapid single-plex PCR, multiplex short tandem repeat (STR) amplification, and second strand cDNA synthesis. PMID:25826708

  14. The rotary zone thermal cycler: a low-power system enabling automated rapid PCR.

    PubMed

    Bartsch, Michael S; Edwards, Harrison S; Lee, Daniel; Moseley, Caroline E; Tew, Karen E; Renzi, Ronald F; Van de Vreugde, James L; Kim, Hanyoup; Knight, Daniel L; Sinha, Anupama; Branda, Steven S; Patel, Kamlesh D

    2015-01-01

    Advances in molecular biology, microfluidics, and laboratory automation continue to expand the accessibility and applicability of these methods beyond the confines of conventional, centralized laboratory facilities and into point of use roles in clinical, military, forensic, and field-deployed applications. As a result, there is a growing need to adapt the unit operations of molecular biology (e.g., aliquoting, centrifuging, mixing, and thermal cycling) to compact, portable, low-power, and automation-ready formats. Here we present one such adaptation, the rotary zone thermal cycler (RZTC), a novel wheel-based device capable of cycling up to four different fixed-temperature blocks into contact with a stationary 4-microliter capillary-bound sample to realize 1-3 second transitions with steady state heater power of less than 10 W. We demonstrate the utility of the RZTC for DNA amplification as part of a highly integrated rotary zone PCR (rzPCR) system that uses low-volume valves and syringe-based fluid handling to automate sample loading and unloading, thermal cycling, and between-run cleaning functionalities in a compact, modular form factor. In addition to characterizing the performance of the RZTC and the efficacy of different online cleaning protocols, we present preliminary results for rapid single-plex PCR, multiplex short tandem repeat (STR) amplification, and second strand cDNA synthesis.

  15. The rotary zone thermal cycler: A low-power system enabling automated rapid PCR

    DOE PAGES

    Bartsch, Michael S.; Edwards, Harrison S.; Gas Transmission Systems, Walnut Creek, CA; ...

    2015-03-31

    In this study, advances in molecular biology, microfluidics, and laboratory automation continue to expand the accessibility and applicability of these methods beyond the confines of conventional, centralized laboratory facilities and into point of use roles in clinical, military, forensic, portable, and field-deployed applications. As a result, there is a growing need to adapt the unit operations of molecular biology such as aliquoting, centrifuging, mixing, and thermal cycling to compact, portable, low-power, and automation-ready formats. Here we present one such adaptation, the rotary zone thermal cycler (RZTC), a novel wheel-based device capable of cycling up to four different fixed-temperature blocks intomore » contact with a stationary 4-microliter capillary-bound sample to realize 1-3 second transitions with steady state heater power of less than 10 W. We further demonstrate the utility of the RZTC for DNA amplification as part of a highly integrated rotary zone PCR (rzPCR) system using low-volume valves and syringe-based fluid handling to automate sample loading and unloading, thermal cycling, and between run cleaning functionalities in a compact, modular form factor. In addition to characterizing the performance of the RZTC and the efficacy of different online cleaning protocols, preliminary results are presented for rapid single-plex PCR, multiplex short tandem repeat (STR) amplification, and second strand cDNA synthesis.« less

  16. Influence of Rapid Thermal Ramp Rate on Phase Transformation of Titanium Silicides

    SciTech Connect

    Bailey, Glenn; Hu, Yao, Zhi; Smith, Paul Martin; Tay, Sing Pin; Thakur, Randhir; Yang, Jiting

    1999-05-03

    ULSI technology requires low resistance, stable silicides formed on small geometry lines. Titanium disilicide (TiSiz), which is the most widely used silicide for ULSI applications, exists in two crystallographic phases: the high resistance, metastable C49 phase and the low resistance, stable C54 phase. The major issue with TiSiz is the increasing thermal budget required to transform the C49 phase into the low resistance C54 phase as linewiths decrease below 0.25 pm. Annealing above 900"C to obtain this transformation often results in thermal degradation, so it is desirable to reduce the transformation temperature. The transformation temperature has been shown to be a fi.mction of many factors including microstructure, grain size, and impurities. In this paper we report an investig+ion of rapid thermal silicidation of titanium films (250, 400, and 600 A) on single crystalline silicon at temperatures from 300 to 1000"C. The ramp rates for these experiments are 5, 30, 70, and 200oC/s. The transformation temperature decreases as the ramp rate increases and as the initial film thickness increases. Scanning electron microscopy (SEM) is used to analyze the resultant film microstructure. The ramp rate influence on Ti silicidation is also investigated on polycrystalline Si lines with widths ranging from 0.27 to 3.0 pm.

  17. The rotary zone thermal cycler: A low-power system enabling automated rapid PCR

    SciTech Connect

    Bartsch, Michael S.; Edwards, Harrison S.; Lee, Daniel; Moseley, Caroline E.; Tew, Karen E.; Renzi, Ronald F.; Van de Vreugde, James L.; Kim, Hanyoup; Knight, Daniel L.; Sinha, Anupama; Branda, Steven S.; Patel, Kamlesh D.; Wanunu, Meni

    2015-03-31

    In this study, advances in molecular biology, microfluidics, and laboratory automation continue to expand the accessibility and applicability of these methods beyond the confines of conventional, centralized laboratory facilities and into point of use roles in clinical, military, forensic, portable, and field-deployed applications. As a result, there is a growing need to adapt the unit operations of molecular biology such as aliquoting, centrifuging, mixing, and thermal cycling to compact, portable, low-power, and automation-ready formats. Here we present one such adaptation, the rotary zone thermal cycler (RZTC), a novel wheel-based device capable of cycling up to four different fixed-temperature blocks into contact with a stationary 4-microliter capillary-bound sample to realize 1-3 second transitions with steady state heater power of less than 10 W. We further demonstrate the utility of the RZTC for DNA amplification as part of a highly integrated rotary zone PCR (rzPCR) system using low-volume valves and syringe-based fluid handling to automate sample loading and unloading, thermal cycling, and between run cleaning functionalities in a compact, modular form factor. In addition to characterizing the performance of the RZTC and the efficacy of different online cleaning protocols, preliminary results are presented for rapid single-plex PCR, multiplex short tandem repeat (STR) amplification, and second strand cDNA synthesis.

  18. Rapid detection of chemical hazards (toxins, dioxins, and PCBs) in seafood.

    PubMed

    Arvanitoyannis, Ioannis S; Kotsanopoulos, Konstantinos V; Papadopoulou, Anna

    2014-01-01

    Among the various hazards occurring in fish and seafood chemical hazards and in particular toxins (ciguatera, scombroid fish poisoning, paralytic shellfish poisoning, neurotoxic (brevetoxic) shellfish poisoning, puffer fish poisoning, diarrhetic shellfish poisoning) have an important place in food poisoning cases. On the other hand, some of the chemical hazards are often due to the pollution of the environment (heavy metals, dioxins, polychlorinated biphenyls, and halogenated aromatic hydrocarbons) and their detection is neither rapid nor facile. As a result there was a great need for developing new rapid and effective methods toward the chemical hazards determination mainly because of their high toxicity. The aim of this review is to provide the information about the new up-to-date detection techniques (Immunological, Chemical and Biochemical, and Molecular assays) in conjunction with detection limits. The latter is made possible by means of inclusion of seven comprehensive and, in most case cases, very extended tables. A reference is also made on the risk characterization of toxins as regards their importance to food contamination or poisoning.

  19. Rapid solid-phase peptide synthesis using thermal and controlled microwave irradiation.

    PubMed

    Bacsa, Bernadett; Desai, Bimbisar; Dibó, Gábor; Kappe, C Oliver

    2006-10-01

    A rapid and efficient microwave-assisted solid-phase synthesis method is described for the preparation of the nonapeptide WDTVRISFK, using conventional Fmoc/Bu(t) orthogonal protection strategy. The synthesis protocol is based on the use of cycles of pulsed microwave irradiation with intermittent cooling of the reaction during the removal of the Fmoc protecting group and during the coupling. The desired nonapeptide was obtained in highest yield and purity by employing MicroKan technology. The chemical reactions were carried out in a single-mode microwave reactor, equipped with a fiber-optic probe to monitor the reaction temperature continuously.

  20. Roles of thermal adaptation and chemical ecology in Liriomyza distribution and control.

    PubMed

    Kang, Le; Chen, Bing; Wei, Jia-Ning; Liu, Tong-Xian

    2009-01-01

    Many Liriomyza species are pests of agricultural and ornamental plants. In the past two decades, the occurrence and distribution of certain Liriomyza species have changed dramatically, leading to an extensive body of research papers. First, we review the association of thermal tolerance with population dynamics, geographic distribution, and species displacement. Differences in thermal tolerances between species result in their differential geographic locations and overwintering ranges. Displacements among Liriomyza species are associated with their temperature adaptation. We examine the chemical linkage of plants, Liriomyza, and their parasitoids. Chemical compounds from host and nonhost plants mediate the behavior of Liriomyza and their parasitoids. Liriomyza and their parasitoids use chemical cues to locate their hosts. Induced compounds can be used as attractants of parasitoids or repellents of Liriomyza. Thus, understanding the thermal tolerances and chemical ecology of Liriomyza may enable researchers to predict geographic distribution and to develop novel control strategies.

  1. Studies on Rapidly Frozen Suspensions of Yeast Cells by Differential Thermal Analysis and Conductometry

    PubMed Central

    Mazur, Peter

    1963-01-01

    Few, if any, yeast cells survived rapid cooling to -196°C and subsequent slow warming. After rapid freezing, the suspensions absorbed latent heat of fusion between -15° and 0°C during warming, and the relation between the amount of heat absorbed and the concentration of cells was the same as that in equivalent KCl solutions, indicating that frozen suspensions behave thermally like frozen solutions. The amount of heat absorbed was such that more than 80 per cent of the intracellular solution had to be frozen. The conductometric behavior of frozen suspensions showed that cell solutes were still inside the cells and surrounded by an intact cell membrane at the time heat was being absorbed. Two models are consistent with these findings. The first assumes that intracellular freezing has taken place; the second that all freezable water has left the cells and frozen externally. The latter model is ruled out because rapidly cooled cells do not shrink by an amount equal to the volume of water that would have to be withdrawn to prevent internal freezing. PMID:13934216

  2. Rapid acidification of the ocean during the Paleocene-Eocene thermal maximum.

    PubMed

    Zachos, James C; Röhl, Ursula; Schellenberg, Stephen A; Sluijs, Appy; Hodell, David A; Kelly, Daniel C; Thomas, Ellen; Nicolo, Micah; Raffi, Isabella; Lourens, Lucas J; McCarren, Heather; Kroon, Dick

    2005-06-10

    The Paleocene-Eocene thermal maximum (PETM) has been attributed to the rapid release of approximately 2000 x 10(9) metric tons of carbon in the form of methane. In theory, oxidation and ocean absorption of this carbon should have lowered deep-sea pH, thereby triggering a rapid (<10,000-year) shoaling of the calcite compensation depth (CCD), followed by gradual recovery. Here we present geochemical data from five new South Atlantic deep-sea sections that constrain the timing and extent of massive sea-floor carbonate dissolution coincident with the PETM. The sections, from between 2.7 and 4.8 kilometers water depth, are marked by a prominent clay layer, the character of which indicates that the CCD shoaled rapidly (<10,000 years) by more than 2 kilometers and recovered gradually (>100,000 years). These findings indicate that a large mass of carbon (>2000 x 10(9) metric tons of carbon) dissolved in the ocean at the Paleocene-Eocene boundary and that permanent sequestration of this carbon occurred through silicate weathering feedback.

  3. Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

    PubMed

    Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

    2017-08-09

    High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V2O5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V2O5 cathode was significantly decreased from 2.5 × 10(4) to 71 Ω·cm(2) at room temperature and from 170 to 31 Ω·cm(2) at 100 °C. Additionally, the diffusion resistance in the V2O5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm(2) and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V2O5 cathode and garnet solid electrolyte without compromising battery safety or performance.

  4. A Rapid and Low-Cost PCR Thermal Cycler for Infectious Disease Diagnostics

    PubMed Central

    Chan, Kamfai; Wong, Pui-Yan; Yu, Peter; Hardick, Justin; Wong, Kah-Yat; Wilson, Scott A.; Wu, Tiffany; Hui, Zoe; Gaydos, Charlotte; Wong, Season S.

    2016-01-01

    The ability to make rapid diagnosis of infectious diseases broadly available in a portable, low-cost format would mark a great step forward in global health. Many molecular diagnostic assays are developed based on using thermal cyclers to carry out polymerase chain reaction (PCR) and reverse-transcription PCR for DNA and RNA amplification and detection, respectively. Unfortunately, most commercial thermal cyclers are expensive and need continuous electrical power supply, so they are not suitable for uses in low-resource settings. We have previously reported a low-cost and simple approach to amplify DNA using vacuum insulated stainless steel thermoses food cans, which we have named it thermos thermal cycler or TTC. Here, we describe the use of an improved set up to enable the detection of viral RNA targets by reverse-transcription PCR (RT-PCR), thus expanding the TTC’s ability to identify highly infectious, RNA virus-based diseases in low resource settings. The TTC was successful in demonstrating high-speed and sensitive detection of DNA or RNA targets of sexually transmitted diseases, HIV/AIDS, Ebola hemorrhagic fever, and dengue fever. Our innovative TTC costs less than $200 to build and has a capacity of at least eight tubes. In terms of speed, the TTC’s performance exceeded that of commercial thermal cyclers tested. When coupled with low-cost endpoint detection technologies such as nucleic acid lateral-flow assay or a cell-phone-based fluorescence detector, the TTC will increase the availability of on-site molecular diagnostics in low-resource settings. PMID:26872358

  5. A Rapid and Low-Cost PCR Thermal Cycler for Infectious Disease Diagnostics.

    PubMed

    Chan, Kamfai; Wong, Pui-Yan; Yu, Peter; Hardick, Justin; Wong, Kah-Yat; Wilson, Scott A; Wu, Tiffany; Hui, Zoe; Gaydos, Charlotte; Wong, Season S

    2016-01-01

    The ability to make rapid diagnosis of infectious diseases broadly available in a portable, low-cost format would mark a great step forward in global health. Many molecular diagnostic assays are developed based on using thermal cyclers to carry out polymerase chain reaction (PCR) and reverse-transcription PCR for DNA and RNA amplification and detection, respectively. Unfortunately, most commercial thermal cyclers are expensive and need continuous electrical power supply, so they are not suitable for uses in low-resource settings. We have previously reported a low-cost and simple approach to amplify DNA using vacuum insulated stainless steel thermoses food cans, which we have named it thermos thermal cycler or TTC. Here, we describe the use of an improved set up to enable the detection of viral RNA targets by reverse-transcription PCR (RT-PCR), thus expanding the TTC's ability to identify highly infectious, RNA virus-based diseases in low resource settings. The TTC was successful in demonstrating high-speed and sensitive detection of DNA or RNA targets of sexually transmitted diseases, HIV/AIDS, Ebola hemorrhagic fever, and dengue fever. Our innovative TTC costs less than $200 to build and has a capacity of at least eight tubes. In terms of speed, the TTC's performance exceeded that of commercial thermal cyclers tested. When coupled with low-cost endpoint detection technologies such as nucleic acid lateral-flow assay or a cell-phone-based fluorescence detector, the TTC will increase the availability of on-site molecular diagnostics in low-resource settings.

  6. Development of thermal desorption gas chromatography/mass spectrometry as a rapid method for ambient particulate characterization

    NASA Astrophysics Data System (ADS)

    Sheya, Sue Anne N.

    A direct thermal desorption gas chromatography/mass spectrometry (TD GC/MS) method for air particulate matter (PM) analysis of volatile and semivolatile organic compounds was investigated. This technique uses a specially designed microdesorption GC inlet utilizing an inductively heated ferromagnetic foil with a Curie point temperature suitable for desorption, which can accommodate microgram amounts of material deposited on a thin strip of quartz fiber filter. Liquid or solid samples can be rapidly desorbed within 10 s at 315°C, followed by 30--40 min of chromatography time. The results obtained by this technique were found to be statistically equivalent to those obtained by the conventional solvent extraction gas chromatography/mass spectrometry (SX GC/MS) method for analysis of aromatic and n alkane standards, single source soot particles, and PM 10 filter samples. Correlations between injecting an extract, desorbing an extract, and desorbing particles averaged R = 0.94, with a three way correlation averaging R = 0.97. High volume sampling conducted at 12 spatially distributed sites located along the US/Mexican border of the El Paso/Juarez metroplex supplied 24h PM 10 filters for an investigation combining thermal desorption with a rapid online chemical derivatization procedure, and multivariate methods of source attribution using principal component and canonical correlation analysis of the resultant chemical markers. Four major combustion related PM emission sources were revealed at these sites: automotive, waste burning, biomass burning and meat cooking. A second investigation conducted in the same area used mediumvolume sampling to collect 2 h timeresolved PM 10 receptor samples for TD GC/MS analysis. Additionally, 2 h samples for inorganic analysis, multichannel particle size distribution measurements, and meteorological data were collected enabling generation of circadian PM multicharacterization profiles. Factor analysis based receptor modeling using

  7. Determination of cell wall teichoic acid structure of staphylococci by rapid chemical and serological screening methods.

    PubMed

    Endl, J; Seidl, P H; Fiedler, F; Schleifer, K H

    1984-03-01

    Investigations of cell wall teichoic acid structures of various staphylococci were carried out by a rapid method based on the gas-liquid chromatographic separation of products obtained after treatment of phenol-extracted cells with 70% hydrofluoric acid. In most of the strains teichoic acids of the poly(glycerolphosphate) and/or poly(ribitol-phosphate) type were found. Teichoic acids of the poly(glycerolphosphate-N-acetylglucosaminephosphate) type and polymers consisting of N-acetylglucosaminephosphate were present in few strains. The results obtained by the rapid chemical screening method were compared with data obtained by serological analysis of teichoic acid structures using specific antisera and the lectin wheat germ agglutinin. Teichoic acid components occurring in low concentrations could only be detected with the chemical and not with the serological method. A number of strains of species of the genus Staphylococcus have been studied using these rapid methods. With a few exceptions, the teichoic acid structure proved to be a constant marker within a given species.

  8. Experimental analysis of the tube life problem with pulse thermal, chemical, and mechanical actions

    NASA Astrophysics Data System (ADS)

    Fan, Lei; Liu, Wei Ming; Jun, Zhao; Xu, Cheng

    2008-11-01

    In this paper, a life testing system of a gun barrel was set up and a set of experiment was used for the diagnostics of gun barrel erosion in rapid-fire condition. The progressive erosion micrographs of the bore surface of a gun tube are obtained by means of a special optical method. Muzzle velocity and the progressive change of the loss of the muzzle velocity in the life time are measured by projectile velocity measurement system. The progressive change of the bore dimensions of the test barrel is monitored. Surface temperature distribution of the gun barrel is measured by the thermocouples. A thermal-solid coupled model of a gun barrel in cyclic firing condition is built and transient temperature field is presented. Theoretical calculations and experimental measurements indicate that heat is transferred from the pulse hot gas to the bore surface by forced convection, further raising the bore surface temperature, which not only reduces the gun mechanical strength, but also promotes chemical interactions. It is one of the key factors of the gun barrel erosion life. New understanding of performance decay and its mechanisms of a machine gun barrel in lifetime are presented.

  9. Structure-Property Evaluation of Thermally and Chemically Gelling Injectable Hydrogels for Tissue Engineering

    PubMed Central

    Ekenseair, Adam K.; Boere, Kristel W. M.; Tzouanas, Stephanie N.; Vo, Tiffany N.; Kasper, F. Kurtis; Mikos, Antonios G.

    2012-01-01

    The impact of synthesis and solution formulation parameters on the swelling and mechanical properties of a novel class of thermally and chemically gelling hydrogels combining poly(N-isopropylacrylamide)-based thermogelling macromers containing pendant epoxy rings with polyamidoamine-based hydrophilic and degradable diamine crosslinking macromers was evaluated. Through variation of network hydrophilicity and capacity for chain rearrangement, the often problematic tendency of thermogelling hydrogels to undergo significant syneresis was addressed. The demonstrated ability to easily tune post-formation dimensional stability at both the synthesis and formulation stages represents a significant novel contribution towards efforts to utilize poly(N-isopropylacrylamide)-based polymers as injectable biomaterials. Furthermore, the cytocompatibility of the hydrogel system under relevant conditions was established, while demonstrating time- and dose-dependent cytotoxicity at high solution osmolality. Such injectable in situ forming degradable hydrogels with tunable water content are promising candidates for many tissue engineering applications, particularly for cell delivery to promote rapid tissue regeneration in non-load-bearing defects. PMID:22881074

  10. A Novel Thermal Sensor for the Sensitive Measurement of Chemical Oxygen Demand

    PubMed Central

    Yao, Na; Liu, Zhuan; Chen, Ying; Zhou, Yikai; Xie, Bin

    2015-01-01

    A novel rapid methodology for determining the chemical oxygen demand (COD) based on a thermal sensor with a flow injection analysis system was proposed and experimentally validated. The ability of this sensor to detect and monitor COD was based on the degree of enthalpy increase when sodium hypochlorite reacted with the organic content in water samples. The measurement results were correlated with COD and were compared against the conventional method using potassium dichromate. The assay required only 5–7 min rather than the 2 h required for evaluation by potassium dichromate. The linear range was 5–1000 mg/L COD, and the limit of detection was very low, 0.74 mg/L COD. Moreover, this method exhibited high tolerance to chloride ions; 0.015 mol/L chloride ions had no influence on the response. Finally, the sensor was used to detect the COD of different water samples; the results were verified by the standard dichromate method. PMID:26295397

  11. Chemical detection using the airborne thermal infrared imaging spectrometer (TIRIS)

    SciTech Connect

    Gat, N.; Subramanian, S.; Sheffield, M.; Erives, H.; Barhen, J.

    1997-04-01

    A methodology is described for an airborne, downlooking, longwave infrared imaging spectrometer based technique for the detection and tracking of plumes of toxic gases. Plumes can be observed in emission or absorption, depending on the thermal contrast between the vapor and the background terrain. While the sensor is currently undergoing laboratory calibration and characterization, a radiative exchange phenomenology model has been developed to predict sensor response and to facilitate the sensor design. An inverse problem model has also been developed to obtain plume parameters based on sensor measurements. These models, the sensors, and ongoing activities are described.

  12. Rapid assessment of marine pollution using multiple biomarkers and chemical immunoassays.

    PubMed

    Galloway, Tamara S; Sanger, Ross C; Smith, Karen L; Fillmann, Gilberto; Readman, James W; Ford, Timothy E; Depledge, Michael H

    2002-05-15

    To fully assess the impact of pollutant releases into the environment, it is necessary to determine both the concentration of chemicals accumulating in biota and the biological effects they give rise to. Owing to time, expertise, and cost constraints, this is, however, rarely achieved. Here, quick, simple to perform, and inexpensive biomarkers and chemical immunoassays were combined in a rapid assessment approach to measure exposure to and effects of organic and metal pollutants on the ribbed mussel (Geukensia demmissa) from New Bedford Harbor, MA. Significant differences in polychlorinated biphenyl (PCB) and polyaromatic hydrocarbon (PAH) tissue residue concentrations were detected among sites using RaPID immunoassay. Selected analyses were verified using GC/MS. No significant differences were observed in metal concentrations (Cu, Cd, Pb, As, Hg, Ni) throughout the area. While causality cannot be attributed, multivariate canonical correlation analysis indicated that PCB and PAH concentrations were strongly associated with the induction of biomarkers of genotoxicity (micronucleus formation), immunotoxicity (spontaneous cytotoxicity), and physiological impairment (heart rate). It is concluded thatthe incorporation of chemical immunoassays with biological monitoring tools into routine management procedures is clearly viable and valuable as a means of identifying toxic impacts of pollutants on biota in situ.

  13. Chemical properties and cytotoxicity of thermally oxidized oil.

    PubMed

    Totani, Nagao; Burenjargal, Munkhjargal; Yawata, Miho; Ojiri, Yuko

    2008-01-01

    Heated frying oils with different chemical properties in terms of AV (acid value), POV (peroxide value), COV (carbonyl value), and contents of polar compounds (PC) and triacylglycerol (TG), as well as color and odor, were obtained. Male Wistar rats were fed ad libitum for 12 weeks a powdered diet (AIN93G; no fat) containing 7 wt% of fresh oil (control) or one of the frying oils described above. The rats were subjected to anthropometric measurements, hematological analyses, and observations of the liver and kidneys. All of the rats grew well, and no gross symptoms attributable to the experimental oils were observed. However, the rats fed a diet containing the heated oil developed apparent liver damage to different degrees regardless of the chemical properties of the ingested oils. Thus, it was suggested that the chemical properties evaluated here had little to do with the cytotoxicity of heated oil, although the properties express quality of oil. Volatile compounds seem to be major candidates for the toxic agents in heated oil because oils with rancid and deteriorated odor show strong toxicity.

  14. Monitoring chemical and physical changes during thermal flavor generation.

    PubMed

    Turner, Jennifer A; Sivasundaram, Lalitha R; Ottenhof, Marie-Astrid; Farhat, Imad A; Linforth, Robert S T; Taylor, Andrew J

    2002-09-11

    On-line techniques were developed to monitor chemical and physical changes occurring during the heating of skim milk powder (SMP). Atmospheric pressure chemical ionization mass spectrometry (APCIMS) followed the generation and release of volatile compounds from SMP in a packed-bed reactor. Operating conditions were optimized to avoid condensation of high boiling compounds such as maltol, and the system was highly reproducible (CV < 7%). Differential scanning calorimetry (DSC) of SMP identified a potential glass transition at an onset temperature of 67.9 degrees C and a series of exothermic events that were related to different stages of the Maillard reaction. No lactose crystallization was found after heating. Using a heated stage reflectance FTIR device, spectra were obtained at different temperatures. Analysis of the data showed a correlation between the intensity ratio at wavenumbers 1017 and 1064 cm(-1) and the glass transition measured by DSC. This FTIR system was not sensitive enough to detect Maillard intermediates. Combining data from the three techniques provides a fuller picture of the physical changes during the Maillard reaction and their effects on the chemical reactions.

  15. Rapid thermal annealing and crystallization mechanisms study of silicon nanocrystal in silicon carbide matrix

    PubMed Central

    2011-01-01

    In this paper, a positive effect of rapid thermal annealing (RTA) technique has been researched and compared with conventional furnace annealing for Si nanocrystalline in silicon carbide (SiC) matrix system. Amorphous Si-rich SiC layer has been deposited by co-sputtering in different Si concentrations (50 to approximately 80 v%). Si nanocrystals (Si-NC) containing different grain sizes have been fabricated within the SiC matrix under two different annealing conditions: furnace annealing and RTA both at 1,100°C. HRTEM image clearly reveals both Si and SiC-NC formed in the films. Much better "degree of crystallization" of Si-NC can be achieved in RTA than furnace annealing from the research of GIXRD and Raman analysis, especially in high-Si-concentration situation. Differences from the two annealing procedures and the crystallization mechanism have been discussed based on the experimental results. PMID:21711625

  16. EMMI rapid reaction task force on ‘Thermalization in non-Abelian plasmas’

    NASA Astrophysics Data System (ADS)

    Berges, Jürgen; Blaizot, Jean-Paul; Gelis, François

    2012-08-01

    Recently, different proposals have been put forward on how thermalization proceeds in heavy-ion collisions in the idealized limit of very large nuclei at sufficiently high energy. Important aspects of the parametric estimates at weak coupling may be tested using well-established classical-statistical lattice simulations of the far-from-equilibrium gluon dynamics. This has to be confronted with strong coupling scenarios in related theories based on gauge-string dualities. Furthermore, closely related questions about far-from-equilibrium dynamics arise in early-universe cosmology and in non-relativistic systems of ultracold atoms. These were central topics of the EMMI Rapid Reaction Task Force meeting held on 12-14 December 2011, at the University of Heidelberg, which we report on. Communicated by Professor Achim Schwenk

  17. The photoluminescence in Si+-implanted SiO2 films with rapid thermal anneal

    NASA Astrophysics Data System (ADS)

    Chou, Shu-Tsun; Tsai, Jen-Hwan; Sheu, Bor-Chiou

    1998-05-01

    Two photoluminescence (PL) bands were observed from Si+-implanted SiO2 films after rapid thermal anneal (RTA) at ⩾950 °C. The PL band at 2.2 eV was obtained from the films with RTA in dry nitrogen and the other one at 1.9 eV was obtained from the films with RTA in wet nitrogen. The luminescence at 2.2 eV disappeared after the films were reannealed with an electrical oven at ⩾600 °C, which is similar to the behavior of oxygen- and hydrogen-deficient structures, and therefore, the mechanism of this PL band was attributed to the Eδ' center. The other one at the 1.9 eV band, being related closely to Si-O-H structures and still appearing after being reannealed to 800 °C, could be ascribed to the effect of nonbridging oxygen hole centers.

  18. Cobalt silicide formation caused by arsenic ion beam mixing and rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Ye, Min; Burte, Edmund; Tsien, Pei-Hsin; Ryssel, Heiner

    1991-04-01

    Ion beam mixing and rapid thermal annealing (RTA) were used to prepare low resistivity (≈ 23 μΩ cm) cobalt disilicide, CoSi 2, layers. Through-metal As + ion implantation causes some mixing between Co and Si resulting in the formation of cobalt suicides. By using RTA, the silicide formation happens in the phase sequence Co 2Si, CoSi and CoSi 2. Samples which were only subjected to a one-step high temperature RTA process ( T ≥. 900°C, 1s) show significant lateral growth of cobalt suicides. By ion beam mixing of Co and Si this lateral silicide growth could be reduced efficiently. Furthermore one can get a very homogeneous CoSi 2 layer.

  19. Behaviour of implanted arsenic during rapid thermal annealing of Ti on Si

    NASA Astrophysics Data System (ADS)

    Ponpon, J. P.; Saulnier, A.; Stuck, R.

    1987-11-01

    The reaction during rapid thermal annealing of the Ti-Si couple with arsenic implanted either into titanium or into silicon has been investigated from the point of view of suicide formation kinetics and impurity redistribution. In contrast with similar experiments on other refractory metals, tungsten for example, the reaction is not blocked by the presence of arsenic but a temperature and dose dependent impurity effect leading to a lowering of the growth rate of the disilicide phase is observed. This has been attributed to arsenic segregation in the grain boundaries of the growing suicide which reduces the transport of silicon via easy diffusion paths towards the unreacted metal or a metal rich suicide phase. Arsenic, when present in the metal, has been found to produce the same effects as oxygen at the early beginning of the annealing. However, after the reaction has started the respective behaviour and influence of arsenic and oxygen become completely different.

  20. Preparation and rapid thermal annealing of AlN thin films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Liu, B.; Gao, J.; Wu, K. M.; Liu, C.

    2009-05-01

    AlN films were grown at 785 ∘C on (0001) sapphire substrates by radio-frequency assisted molecular beam epitaxy. Post-growth rapid thermal annealing (RTA) was carried out from 900 to 1200 ∘C for 10 s in flowing N 2. The morphological and structural properties of the AlN epilayers before and after the RTA were studied by atomic force microscopy, x-ray diffraction and transmission electron microscopy. It is found that the threading dislocations can be decreased to an order of magnitude by using an interlayer growth method. The surface roughness (RMS) of the AlN thin films becomes larger with the increase of annealing temperature. The full width at half maximum of AlN (0002) rocking curve reaches its minimum after the RTA at 1000 ∘C.

  1. Thermal, chemical, and photocatalytic inactivation of Lactobacillus plantarum bacteriophages.

    PubMed

    Briggiler Marcó, Mariángeles; De Antoni, Graciela L; Reinheimer, Jorge A; Quiberoni, Andrea

    2009-05-01

    The effect of several biocides, thermal treatments, and photocatalysis on the viability of four Lactobacillus plantarum phages was investigated. Times to achieve 99% inactivation (T99) of phages at 63, 72, and 90 degrees C were evaluated in four suspension media: deMan Rogosa Sharpe broth, reconstituted skim milk, a commercial EM-glucose medium, and Tris magnesium gelatin buffer. The four phages studied were highly resistant to 63 degrees C (T99 > 45 min); however, counts < 10 PFU/ml were achieved by heating at 90 degrees C for 5 min. Higher thermal resistance at 72 degrees C was observed when reconstituted skim milk and EM-glucose medium were assayed. Peracetic acid (0.15%, vol/vol) was an effective biocide for the complete inactivation of all phages studied within 5 min of exposure. Sodium hypochlorite (800 ppm) inactivated the phages completely within 30 min. Ethanol (100%) did not destroy phage particles even after 45 min. Isopropanol did not have any effect on phage viability. Phage counts < 50 PFU/ml were obtained within 180 min of photocatalytic treatment. The results obtained in this work are important for establishing adequate methods for inactivating phages in industrial plants and laboratory environments.

  2. Influence of structure on chemical and thermal stability of aliphatic diesters.

    PubMed

    Raghunanan, Latchmi; Narine, Suresh S

    2013-11-27

    Ester group interactions with each other and with the atoms between them were investigated in order to determine dependence of chemical and thermal stabilities of aliphatic diesters on structure. Novel glycol-derived diesters with chemical formula (C17H33COO)2C(n)H(2n) were used as model systems. Chemical stability was determined using (1)H NMR and FTIR, and thermal stability and weight-loss kinetics were examined using nonisothermal TGA. Chemical stability increased with the number of methylene units (n, carbon) between the ester groups until n = 6, and no significant improvement was observed past n > 6. It is argued that other ester-dense materials, including polyesters, would behave similarly. Evidence of a strong dependence of thermal stability on chemical stability is also provided. This work shows that the chemical and thermal stabilities of ester-dense functional materials such as diesters, oligo-esters, and polyesters can be manipulated by varying the distance between the ester groups, and hence the interactions of the electron-withdrawing ester groups with its neighbors.

  3. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    NASA Astrophysics Data System (ADS)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-07-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  4. [Rapid Identification of Chemical Components in Polygonum multiflorum Formula Granules by UPLC/Q-TOF MS].

    PubMed

    Xu, Ai-li; Dong, Yu-juan; Chen, Zhao; Jiang, Jie-yi; Li, Su-mei; Li, Yang-xue

    2015-06-01

    To establish a simple and reliable method for rapid separation and identification of chemical components in Polygonum multiflorum Formula Granules. An ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometric method( UPLC/Q-TOF MS) was used. The separation was performed on an Agilent Eclipse Plus C18 RRHD(100 mm x 2.1 mm, 1.8 μm) column with a mobile phase of water and acetonitrile in a gradient elution mode. The flow rate was 0.4 mL/min and the column temperature was maintained at 25 degrees C. TOF MS was applied for qualitative analysis under positive ion mode. Five compounds were identified by the time of flight mass spectrometry and literature data. This method is accurate, rapid and sensitive, it can provide reference for the quality control of Polygonum multiflorum Formula Granules.

  5. Rapid Life-History Diversification of an Introduced Fish Species across a Localized Thermal Gradient

    PubMed Central

    Zhu, Fengyue; Rypel, Andrew L.; Murphy, Brian R.; Li, Zhongjie; Zhang, Tanglin; Yuan, Jing; Guo, Zhiqiang; Tang, Jianfeng; Liu, Jiashou

    2014-01-01

    Climatic variations are known to engender life-history diversification of species and populations at large spatial scales. However, the extent to which microgeographic variations in climate (e.g., those occurring within a single large ecosystem) can also drive life-history divergence is generally poorly documented. We exploited a spatial gradient in water temperatures at three sites across a large montane lake in southwest China (Lake Erhai) to examine the extent to which life histories of a short-lived fish species (icefish, Neosalanx taihuensis) diversified in response to thermal regime following introduction 25 y prior. In general, warmwater icefish variants grew faster, had larger adult body size and higher condition and fecundity, but matured at smaller sizes. Conversely, coldwater variants had smaller adult body size and lower condition, but matured at larger sizes and had larger eggs. These life-history differences strongly suggest that key ecological trade-offs exist for icefish populations exposed to different thermal regimes, and these trade-offs have driven relatively rapid diversification in the life histories of icefish within Lake Erhai. Results are surprisingly concordant with current knowledge on life-history evolution at macroecological scales, and suggest that improved conservation management might be possible by focusing on patterns operating at microgeographical, including, within-ecosystem scales. PMID:24505366

  6. Rapid changes in cell physiology as a result of acute thermal stress house sparrows, Passer domesticus.

    PubMed

    Jimenez, Ana G; Williams, Joseph B

    2014-12-01

    Given that our climate is rapidly changing, Physiological Ecologists have the critical task of identifying characteristics of species that make them either resilient or susceptible to changes in their natural air temperature regime. Because climate change models suggest that heat events will become more common, and in some places more extreme, it is important to consider how extreme heat events might affect the physiology of a species. The implications of more frequent heat wave events for birds have only recently begun to be addressed, however, the impact of these events on the cellular physiology of a species is difficult to assess. We have developed a novel approach using dermal fibroblasts to explore how short-term thermal stress at the whole animal level might affect cellular rates of metabolism. House sparrows, Passer domesticus were separated into a "control group" and a "heat shocked" group, the latter acclimated to 43°C for 24h. We determined the plasticity of cellular thermal responses by assigning a "recovery group" that was heat shocked as above, but then returned to room temperature for 24h. Primary dermal fibroblasts were grown from skin of all treatment groups and the pectoralis muscle was collected. We found that glycolysis (ECAR) and oxygen consumption rates (OCR), measured using a Seahorse XF 96 analyzer, were significantly higher in the fibroblasts from the heat shocked group of House sparrows compared with their control counterparts. Additionally, muscle fiber diameters decreased and, in turn, Na(+)-K(+)-ATPase maximal activity in the muscle significantly increased in heat shocked sparrows compared with birds in the control group. All of these physiological alterations due to short-term heat exposure were reversible within 24h of recovery at room temperature. These results show that acute exposure to heat stress significantly alters the cellular physiology of sparrows, but that this species is plastic enough to recover from such a thermal

  7. Rapid thermal processing — where has it been? Where is it going?

    NASA Astrophysics Data System (ADS)

    Russo, Carl

    1985-01-01

    Rapid thermal processing (RTP) is a method which uniformly heats and cools wafers in seconds. Since the process heats the whole wafer, the heating and cooling is limited by the thermal mass of the wafer and the heat transfer mechanism operating on the wafer. The main reason for considering RTP is to obtain improved dopant activation of implanted layers (due to the high wafer temperatures used) while minimizing dopant redistribution (due to short processing times at high temperature). This unique combination of high activation temperature and short processing time provides a degree of control over the thermal processing of wafers not available with standard diffusion furnaces and allows full activation of the dopant introduced by ion implantation without junction motion. Having this improved level of control over implant activation and dopant redistribution, several other important applications can be addressed as well. These applications include: PSG reflow; suicide and salicide processing; polysilicon annealing and drive-in doping from polysilicon; and controlled lattice damage repair. Results of the above applications indicate that activation with minimum dopant redistribution occurs in times less than ten seconds for wafer temperature > 1000°C, PSG reflows in times between 8 s and 30 s; refractory metal suicides can be formed and/or sintered in times on the order of 10 s. Processes are being developed in the other areas. For production applications RTP machines must also demonstrate: process uniformity and reproducibility (e.g., wafer temperature uniformity across the wafer and uniformity from wafer to wafer) and no slip. Slip is due to wafer temperature nonuniformity, plastic deformation of the wafer and/or oxygen concentration in the wafer. To achieve the required level of machine performance, accurate in situ wafer monitoring techniques are required which provide the necessary process/uniformity control without affecting the measured parameters.

  8. Correlation of chemical, structural and thermal properties of natural fibres for their sustainable exploitation.

    PubMed

    Moriana, Rosana; Vilaplana, Francisco; Karlsson, Sigbritt; Ribes, Amparo

    2014-11-04

    The potential of lignocellulosic natural fibres as renewable resources for thermal conversion and material reinforcement is largely dependent on the correlation between their chemical composition, crystalline structure and thermal decomposition properties. Significant differences were observed in the chemical composition of cotton, flax, hemp, kenaf and jute natural fibres in terms of cellulose, hemicellulose and lignin content, which influence their morphology, thermal properties and pyrolysis product distribution. A suitable methodology to study the kinetics of the thermal decomposition process of lignocellulosic fibres is proposed combining different models (Friedman, Flynn-Wall-Ozawa, Criado and Coats-Redfern). Cellulose pyrolysis can be modelled with similar kinetic parameters for all the natural fibres whereas the kinetic parameters for hemicellulose pyrolysis show intrinsic differences that can be assigned to the heterogeneous hemicellulose sugar composition in each natural fibre. This study provides the ground to critically select the most promising fibres to be used either for biofuel or material applications.

  9. Effect of thermal pretreatment on the physical and chemical properties of municipal biomass waste.

    PubMed

    Liu, Xiao; Wang, Wei; Gao, Xingbao; Zhou, Yingjun; Shen, Renjie

    2012-02-01

    The effects of thermal pretreatment on the physical and chemical properties of three typical municipal biomass wastes (MBWs), kitchen waste (KW), vegetable/fruit residue (VFR), and waste activated sludge (WAS) were investigated. The results show that thermal pretreatment at 175 °C/60 min significantly decreases viscosity, improves the MBW dewatering performance, as well as increases soluble chemical oxygen demand, soluble sugar, soluble protein, and especially organic compounds with molecular weights >10 kDa. For KW, VFR and WAS, 59.7%, 58.5% and 25.2% of the organic compounds can be separated in the liquid phase after thermal treatment. WAS achieves a 34.8% methane potential increase and a doubled methane production rate after thermal pretreatment. In contrast, KW and VFR show 7.9% and 11.7% methane decrease because of melanoidin production.

  10. Chemical and Thermal Expansion of Calcium-Doped Lanthanum Chromite

    NASA Astrophysics Data System (ADS)

    Williford, R. E.; Armstrong, T. R.; Gale, J. D.

    2000-02-01

    Atomistic free-energy minimization techniques were used to simulate three simultaneous volumetric shrinkage/expansion phenomena in calcium-doped lanthanum chromite solid oxide fuel cell (SOFC) interconnect materials. Four sets of interatomic potentials were developed and tested over the temperature range 0-1273 K. The predicted unit-cell volumes, elastic properties, volumetric shrinkage due to A-site doping of the ABO3 perovskite (La1-xCax)CrO3, defect-induced volumetric expansion due to reducing atmospheres, and thermal expansion were in reasonable agreement with experiment, though not all concurrently with a single set of potentials. Potentials based either on simple oxides or on partial charge models appeared to give the best overall predictions. Additional experimental data are needed to improve the potentials.

  11. Chemical Properties of Carbon Nanotubes Prepared Using Camphoric Carbon by Thermal-CVD

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Rusop, M.

    2010-03-01

    Chemical properties and surface study on the influence of starting carbon materials by using thermal chemical vapor deposition (Thermal-CVD) to produced carbon nanotubes (CNTs) is investigated. The CNTs derived from camphor were synthesized as the precursor material due to low sublimation temperature. The major parameters are also evaluated in order to obtain high-yield and high-quality CNTs. The prepared CNTs are examined using field emission scanning electron microscopy (FESEM) to determine the microstructure of nanocarbons. The FESEM investigation of the CNTs formed on the support catalysts provides evidence that camphor is suitable as a precursor material for nanotubes formation. The chemical properties of the CNTs were conducted using FTIR spectroscopy and PXRD analysis. The high-temperature graphitization process induced by the Thermal-CVD enables the hydrocarbons to act as carbon sources and changes the aromatic species into the layered graphite structure of CNTs.

  12. Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

    NASA Astrophysics Data System (ADS)

    Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

    2017-06-01

    Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

  13. Chemical Properties of Carbon Nanotubes Prepared Using Camphoric Carbon by Thermal-CVD

    SciTech Connect

    Azira, A. A.; Rusop, M.

    2010-03-11

    Chemical properties and surface study on the influence of starting carbon materials by using thermal chemical vapor deposition (Thermal-CVD) to produced carbon nanotubes (CNTs) is investigated. The CNTs derived from camphor were synthesized as the precursor material due to low sublimation temperature. The major parameters are also evaluated in order to obtain high-yield and high-quality CNTs. The prepared CNTs are examined using field emission scanning electron microscopy (FESEM) to determine the microstructure of nanocarbons. The FESEM investigation of the CNTs formed on the support catalysts provides evidence that camphor is suitable as a precursor material for nanotubes formation. The chemical properties of the CNTs were conducted using FTIR spectroscopy and PXRD analysis. The high-temperature graphitization process induced by the Thermal-CVD enables the hydrocarbons to act as carbon sources and changes the aromatic species into the layered graphite structure of CNTs.

  14. Numerical simulations of thermal-chemical instabilities at the core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Hansen, Ulrich; Yuen, David A.

    1988-01-01

    Numerical simulations of thermal-chemical instabilities in the D-double-prime layer at the core-mantle boundary are presented which show that strong lateral heterogeneities in the composition and density fields can be initiated and maintained dynamically if there is continuous replenishment of material from subduced slabs coming from the upper mantle. These chemical instabilities have a tendency to migrate laterally and may help to support core-mantle boundary topography with short and long wavelengths. The thermal-chemical flows produce a relatively stagnant D-double-prime layer with strong lateral and temporal variations in basal heat flux, which gives rise to thermal core-mantle interactions influencing the geodynamo.

  15. Rapid screening of wood chemical component variations using transmittance near-infrared spectroscopy.

    PubMed

    Yeh, Ting-Feng; Yamada, Tatsuhiko; Capanema, Ewellyn; Chang, Hou-Min; Chiang, Vincent; Kadla, John F

    2005-05-04

    A rapid transmittance near-infrared (NIR) spectroscopy method was developed to predict the variation in chemical composition of solid wood. The effect of sample preparation, sample quantity (single versus stacked multiple wood wafers), and NIR acquisition time on the quantification of alpha-cellulose and lignin content was investigated. Strong correlations were obtained between laboratory wet chemistry values and the NIR-predicted values. In addition to the experimental protocol and method development, improvements in calibration error associated with utilizing stacked multiple wood wafers as opposed to single wood wafers are also discussed.

  16. Codon randomization for rapid exploration of chemical space in thiopeptide antibiotic variants.

    PubMed

    Young, Travis S; Dorrestein, Pieter C; Walsh, Christopher T

    2012-12-21

    Thiopeptide antibiotics exhibit a profound level of chemical diversity that is installed through cascades of posttranslational modifications on ribosomal peptides. Here, we present a technique to rapidly explore the chemical space of the thiopeptide GE37468 through codon randomization, yielding insights into thiopeptide maturation as well as structure and activity relationships. In this incarnation of the methodology, we randomized seven residues of the prepeptide-coding region, enabling the generation of 133 potential thiopeptide variants. Variant libraries were subsequently queried in two ways. First, high-throughput MALDI-TOF mass spectrometry was applied to colony-level expressions to sample mutants that permitted full maturation of the antibiotic. Second, the activity of producing mutants was detected in an antibiotic overlay assay. In total, 29 of the 133 variants produced mature compound, 12 of which retained antibiotic activity and 1 that had improved activity.

  17. Rapid Electrochemical Detection and Identification of Microbiological and Chemical Contaminants for Manned Spaceflight Project

    NASA Technical Reports Server (NTRS)

    Pierson, Duane; Botkin, Douglas; Gazda, Daniel

    2014-01-01

    Microbial control in the spacecraft environment is a daunting task, especially in the presence of human crew members. Currently, assessing the potential crew health risk associated with a microbial contamination event requires return of representative environmental samples that are analyzed in a ground-based laboratory. It is therefore not currently possible to quickly identify microbes during spaceflight. This project addresses the unmet need for spaceflight-compatible microbial identification technology. The electrochemical detection and identification platform is expected to provide a sensitive, specific, and rapid sample-to-answer capability for in-flight microbial monitoring that can distinguish between related microorganisms (pathogens and non-pathogens) as well as chemical contaminants. This will dramatically enhance our ability to monitor the spacecraft environment and the health risk to the crew. Further, the project is expected to eliminate the need for sample return while significantly reducing crew time required for detection of multiple targets. Initial work will focus on the optimization of bacterial detection and identification. The platform is designed to release nucleic acids (DNA and RNA) from microorganisms without the use of harmful chemicals. Bacterial DNA or RNA is captured by bacteria-specific probe molecules that are bound to a microelectrode, and that capture event can generate a small change in the electrical current (Lam, et al. 2012. Anal. Chem. 84(1): 21-5.). This current is measured, and a determination is made whether a given microbe is present in the sample analyzed. Chemical detection can be accomplished by directly applying a sample to the microelectrode and measuring the resulting current change. This rapid microbial and chemical detection device is designed to be a low-cost, low-power platform anticipated to be operated independently of an external power source, characteristics optimal for manned spaceflight and areas where power

  18. Large area super-resolution chemical imaging via rapid dithering of a nanoprobe

    NASA Astrophysics Data System (ADS)

    Languirand, Eric R.; Cullum, Brian M.

    2015-05-01

    Super-resolution chemical imaging via Raman spectroscopy provides a significant ability to simultaneously or pseudosimultaneously monitor numerous label-free analytes while elucidating their spatial distribution on the surface of the sample. However, spontaneous Raman is an inherently weak phenomenon making trace detection and thus superresolution imaging extremely difficult, if not impossible. To circumvent this and allow for trace detection of the few chemical species present in any sub-diffraction limited resolution element of an image, we have developed a surface enhanced Raman scattering (SERS) coherent fiber-optic imaging bundle probe consisting of 30,000 individual fiber elements. When the probes are tapered, etched and coated with metal, they provide circular Raman chemical images of a sample with a field of view of approximately 20μm (i.e. diameter) via the array of 30,000 individual 50 nm fiber elements. An acousto-optic tunable filter is used to rapidly scan or select discrete frequencies for multi- or hyperspectral analysis. Although the 50nm fiber element dimensions of this probe inherently provide spatial resolutions of approximately 100nm, further increases in the spatial resolution can be achieved by using a rapid dithering process. Using this process, additional images are obtained one-half fiber diameter translations in the x- and y- planes. A piezostage drives the movement, providing the accurate and reproducible shifts required for dithering. Optimal probability algorithms are then used to deconvolute the related images producing a final image with a three-fold increase in spatial resolution. This paper describes super-resolution chemical imaging using these probes and the dithering method as well as its potential applications in label-free imaging of lipid rafts and other applications within biology and forensics.

  19. Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Papadakis, V. M.; Müller, B.; Hagenbeek, M.; Sinke, J.; Groves, R. M.

    2016-04-01

    Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

  20. An integrated photo-thermal sensing system for rapid and direct diagnosis of anemia.

    PubMed

    Kwak, Bong Seop; Kim, Hyung Joon; Kim, Hyun Ok; Jung, Hyo-Il

    2010-12-15

    This article presents a thermal biosensor to diagnose the anemia without chemical treatments using temperature increase of red blood cells (RBC) when hemoglobin molecules absorb specific wavelength of photons and convert them to thermal energy. For measuring temperature change of red blood cell, the micro-scaled platinum resistance temperature detector (Pt RTD) was developed. For maintenance of constant ambient temperature, we designed and fabricated a thermostat system. The thermostat system consists of a K-type thermocouple and two electric heaters that serve to increase the system temperature, which is monitored by the thermocouple. Both heaters and the thermocouple were connected to a proportional-integral-derivative (PID) controller and enabled to maintain the temperature constant (<±0.1°C). For specific heating of red blood cell, 8.0 W/cm(2) diode pumped solid state (DPSS) continuous wave (CW) laser module was used with 532 nm wavelength. Using this system, we successfully measured the temperature variations (from 66.33±2.72°C to 74.16±2.06°C) of whole blood samples from 10 anemic patients and subsequently determined the concentration of hemoglobin (from 7.2 g/dL to 9.8 g/dL). The method proposed in this paper requires significantly less amount of whole blood sample (6 μl) compared with the conventional methods (175 μl) and allows instantaneous diagnosis (3 s) of anemia.

  1. Rapid screening of residual pesticides on fruits and vegetables using thermal desorption electrospray ionization mass spectrometry.

    PubMed

    Shiea, Christopher; Huang, Yeou-Lih; Liu, De-Lin; Chou, Chih-Chang; Chou, Jo-Han; Chen, Peng-Yu; Shiea, Jentaie; Huang, Min-Zong

    2015-01-30

    Conventional mass spectrometry is encumbered by laborious and inconvenient sample pretreatment. Ambient thermal desorption electrospray ionization mass spectrometry (TD-ESI-MS) is most noted for its rapid, simple, and sensitive detection capabilities. In this study, TD-ESI-MS was used to rapidly characterize residual pesticides on the surfaces of fruits and vegetables. A direct sampling probe was used to obtain analytes from sample surfaces. MS and MS/MS analyses were performed on fruits and vegetables via TD-ESI-MS. External calibration curves and reproducibility tests were performed using liquid pesticide standards. Pesticide decay and distribution on samples was studied, as well as the removal of residual pesticides via soaking in water or detergent baths. Since sample pretreatment was unnecessary, an analysis was completed in approximately 15 s or less, with no visible sample damage. Mass spectra were obtained for 22 pesticides. Linear calibrations (R(2) from 0.9414-0.999) had limits of detection as low as 0.5 µg·L(-1), with satisfactory reproducibilities for liquids and solids. Pesticides on sample surfaces decayed over 2 weeks under ambient conditions. Residual pesticides localized at the fruit peel. Detergent baths removed more pesticide than water baths. TD-ESI-MS was used to rapidly screen residual pesticides in liquids and solids. Pesticides were found on fruits and vegetables, where the decay, distribution, and removal of pesticides on samples were also explored. Due to short analysis times, the technique allows for high-throughput analyses for applications in food and environmental safety. Copyright © 2014 John Wiley & Sons, Ltd.

  2. Chemical compositions and classifica tion of five thermally altered carbonaceous chondrites

    NASA Astrophysics Data System (ADS)

    Noronha, Bianca A.; Friedrich, Jon M.

    2014-08-01

    To establish the chemical group provenance of the five thermally altered carbonaceous chondrites Asuka (A-) 881551, Asuka-882113, Elephant Moraine (EET) 96026, Mulga (west), and Northwest Africa (NWA) 3133, we quantified 44 trace elements in each of them. We also analyzed Larkman Nunatak (LAR) 04318 (CK4), Miller Range (MIL) 090001 (CR2), Roberts Massif (RBT) 03522 (CK5) as reference samples as their chemical group affinity is already recognized. We conclude that Asuka-881551, Asuka-882113, and Mulga (west) are thermally metamorphosed CK chondrites. Compositionally, Elephant Moraine 96026 most resembles the CV chondrites. NWA 3133 is the most significantly thermally altered carbonaceous chondrite in our suite of samples. It is completely recrystallized (no chondrules or matrix remain), but its bulk composition is consistent with a CV-CK clan provenance. The thermally labile element (e.g., Se, Te, Zn, and Bi) depletion in NWA 3133 indicates a chemically open system during the heating episode. It remains unclear if the heat necessary for its thermal alteration of NWA 3133 was due to the decay of 26Al or was impact related. Finally, we infer that MIL 090001, Mulga (west), and NWA 3133 show occasional compositional signatures indicative of terrestrial alteration. The alteration is especially evident within the elements Sr, Ba, La, Ce, Th, U, and possibly Sb. Despite the alteration, we can still confidently place each of the altered chondrites within an established chemical group or clan.

  3. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    NASA Astrophysics Data System (ADS)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen; Sun, Wenjing

    2015-01-01

    In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C1/C2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  4. Implication of rapid thermal annealing-induced cracks on the performance of multiple-quantum-well laser diodes.

    PubMed

    Yee, Hoshin H; Yu, Chih-Ping

    2003-05-20

    We investigated the effects of rapid thermal annealing (RTA)-induced cracks on the diode performance fabricated with GaAs-AlGaAs microstructures. These effects were examined and characterized after quantum-well intermixing within an epitaxial structure capped by either SiO2 or SrF2 layers. The results show clearly that the density of surface crackes strongly depends on the atomic interdiffusion between the well and the barrier layers and on the quality of the dielectric caps as well. Moreover, surface-crack correlation with the RTA process an dielectric deposition parameters, and the cracking effects on diode performance were observed and analyzed in detail. The results demonstrate that diode characteristics can be greatly improved by good surface morphology. Most importantly, we explored an effective way of reducing the density of RTA-induced cracks for the dielectrics grown by plasma-enhanced chemical vapor deposition, which was beneficial for dielectric-cap quantum-well disordering.

  5. Predicting Formation Damage in Aquifer Thermal Energy Storage Systems Utilizing a Coupled Hydraulic-Thermal-Chemical Reservoir Model

    NASA Astrophysics Data System (ADS)

    Müller, Daniel; Regenspurg, Simona; Milsch, Harald; Blöcher, Guido; Kranz, Stefan; Saadat, Ali

    2014-05-01

    In aquifer thermal energy storage (ATES) systems, large amounts of energy can be stored by injecting hot water into deep or intermediate aquifers. In a seasonal production-injection cycle, water is circulated through a system comprising the porous aquifer, a production well, a heat exchanger and an injection well. This process involves large temperature and pressure differences, which shift chemical equilibria and introduce or amplify mechanical processes. Rock-fluid interaction such as dissolution and precipitation or migration and deposition of fine particles will affect the hydraulic properties of the porous medium and may lead to irreversible formation damage. In consequence, these processes determine the long-term performance of the ATES system and need to be predicted to ensure the reliability of the system. However, high temperature and pressure gradients and dynamic feedback cycles pose challenges on predicting the influence of the relevant processes. Within this study, a reservoir model comprising a coupled hydraulic-thermal-chemical simulation was developed based on an ATES demonstration project located in the city of Berlin, Germany. The structural model was created with Petrel, based on data available from seismic cross-sections and wellbores. The reservoir simulation was realized by combining the capabilities of multiple simulation tools. For the reactive transport model, COMSOL Multiphysics (hydraulic-thermal) and PHREEQC (chemical) were combined using the novel interface COMSOL_PHREEQC, developed by Wissmeier & Barry (2011). It provides a MATLAB-based coupling interface between both programs. Compared to using COMSOL's built-in reactive transport simulator, PHREEQC additionally calculates adsorption and reaction kinetics and allows the selection of different activity coefficient models in the database. The presented simulation tool will be able to predict the most important aspects of hydraulic, thermal and chemical transport processes relevant to

  6. Thermal, chemical, and optical properties of Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; Hoffman, R.L.; McIntire, D.C.; Buktenica, M.W.; Girdner, S.F.

    2007-01-01

    Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range. The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5??C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in June 1997. The lowest reading was 18.1 m in July 1995. From 1896 (white-dinner plate) to 2003, the average August Secchi disk reading was

  7. An ab initio study of the nickel-catalyzed transformation of amorphous carbon into graphene in rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Chen, Shuang; Xiong, Wei; Zhou, Yun Shen; Lu, Yong Feng; Zeng, Xiao Cheng

    2016-05-01

    Ab initio molecular dynamics (AIMD) simulations are employed to investigate the chemical mechanism underlying the Ni-catalyzed transformation of amorphous carbon (a-C) into graphene in the rapid thermal processing (RTP) experiment to directly grow graphene on various dielectric surfaces via the evaporation of surplus Ni and C at 1100 °C (below the melting point of bulk Ni). It is found that the a-C-to-graphene transformation entails the metal-induced crystallization and layer exchange mechanism, rather than the conventional dissolution/precipitation mechanism typically involved in Ni-catalyzed chemical vapor deposition (CVD) growth of graphene. The multi-layer graphene can be tuned by changing the relative thicknesses of deposited a-C and Ni thin films. Our AIMD simulations suggest that the easy evaporation of surplus Ni with excess C is likely attributed to the formation of a viscous-liquid-like Ni-C solution within the temperature range of 900-1800 K and to the faster diffusion of C atoms than that of Ni atoms above 600 K. Even at room temperature, sp3-C atoms in a-C are quickly converted to sp2-C atoms in the course of the simulation, and the graphitic C formation can occur at low temperature. When the temperature is as high as 1200 K, the grown graphitic structures reversely dissolve into Ni. Because the rate of temperature increase is considerably faster in the AIMD simulations than in realistic experiments, defects in the grown graphitic structures are kinetically trapped. In this kinetic growth stage, the carbon structures grown from sp3-carbon or from sp2-carbon exhibit marked differences.Ab initio molecular dynamics (AIMD) simulations are employed to investigate the chemical mechanism underlying the Ni-catalyzed transformation of amorphous carbon (a-C) into graphene in the rapid thermal processing (RTP) experiment to directly grow graphene on various dielectric surfaces via the evaporation of surplus Ni and C at 1100 °C (below the melting point of bulk

  8. Thermal-work strain in law enforcement personnel during chemical, biological, radiological, and nuclear (CBRN) training

    PubMed Central

    Yokota, M; Karis, A J; Tharion, W J

    2014-01-01

    Background: Thermal safety standards for the use of chemical, biological, radiological, and nuclear (CBRN) ensembles have been established for various US occupations, but not for law enforcement personnel. Objectives: We examined thermal strain levels of 30 male US law enforcement personnel who participated in CBRN field training in Arizona, Florida, and Massachusetts. Methods: Physiological responses were examined using unobtrusive heart rate (HR) monitors and a simple thermoregulatory model to predict core temperature (Tc) using HR and environment. Results: Thermal strain levels varied by environments, activity levels, and type of CBRN ensemble. Arizona and Florida volunteers working in hot-dry and hot-humid environment indicated high heat strain (predicted max Tc>38.5°C). The cool environment of Massachusetts reduced thermal strain although thermal strains were occasionally moderate. Conclusions: The non-invasive method of using physiological monitoring and thermoregulatory modeling could improve law enforcement mission to reduce the risk of heat illness or injury. PMID:24999847

  9. Thermal-work strain in law enforcement personnel during chemical, biological, radiological, and nuclear (CBRN) training.

    PubMed

    Yokota, M; Karis, A J; Tharion, W J

    2014-01-01

    Thermal safety standards for the use of chemical, biological, radiological, and nuclear (CBRN) ensembles have been established for various US occupations, but not for law enforcement personnel. We examined thermal strain levels of 30 male US law enforcement personnel who participated in CBRN field training in Arizona, Florida, and Massachusetts. Physiological responses were examined using unobtrusive heart rate (HR) monitors and a simple thermoregulatory model to predict core temperature (Tc) using HR and environment. Thermal strain levels varied by environments, activity levels, and type of CBRN ensemble. Arizona and Florida volunteers working in hot-dry and hot-humid environment indicated high heat strain (predicted max Tc>38·5°C). The cool environment of Massachusetts reduced thermal strain although thermal strains were occasionally moderate. The non-invasive method of using physiological monitoring and thermoregulatory modeling could improve law enforcement mission to reduce the risk of heat illness or injury.

  10. The application of thermal methods for determining chemical composition of carbonaceous aerosols: a review.

    PubMed

    Chow, Judith C; Yu, Jian Zhen; Watson, John G; Ho, Steven Sai Hang; Bohannan, Theresa L; Hays, Michael D; Fung, Kochy K

    2007-09-01

    Thermal methods of various forms have been used to quantify carbonaceous materials. Thermal/optical carbon analysis provides measurements of organic and elemental carbon concentrations as well as fractions evolving at specific temperatures in ambient and source aerosols. Detection of thermally desorbed organic compounds with thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) identifies and quantifies over 100 individual organic compounds in particulate matter (PM) samples. The resulting mass spectra contain information that is consistent among, but different between, source emissions even in the absence of association with specific organic compounds. TD-GC/MS is a demonstrated alternative to solvent extraction for many organic compounds and can be applied to samples from existing networks. It is amenable to field-deployable instruments capable of measuring organic aerosol composition in near real-time. In this review, thermal stability of organic compounds is related to chemical structures, providing a basis for understanding thermochemical properties of carbonaceous aerosols. Recent advances in thermal methods applied to determine aerosol chemical compositions are summarized and their potential for uncovering aerosol chemistry are evaluated. Current limitations and future research needs of the thermal methods are included.

  11. Rapid characterization of lignocellulosic feedstocks for fuels and chemicals: Molecular beam mass spectrometric approach

    SciTech Connect

    Agblevor, F.A.; Davis, M.F.; Evans, R.J.

    1995-03-01

    Rapid characterization of biomass feedstocks has a pivotal role in the development of biomass energy because of the large number of samples that must be analyzed due to the diversity of biomass feedstocks and the significant differences in the chemical and physical properties of these feedstocks. Conventional chemical analysis of biomass feedstocks, although very useful, is time-consuming and not very practical for large scale screening experiments, hence the need for rapid characterization techniques. The molecular beam mass spectrometer and pyrolysis gas chromatography, which can analyze biomass pyrolysis vapors in real time, are unique tools for rapid qualitative and quantitative analyses of biomass feedstocks. Several biomass feedstocks (herbaceous, woody, and agricultural residues) were screened for the effects of storage, season of harvest, geographic location, clonal, and species variation on the pyrolysis products of the feedstocks. For herbaceous species such as sericea lespedeza, the season of harvest had a significant effect on the pyrolysis products. Effects of clonal variation on the composition of hybrid poplar feedstocks was easily discerned with the molecular beam mass spectrometric analysis. The effect of geographic location on the poplar clones pyrolysis products was minimal. However, in the case of switchgrass, varietal influence on the pyrolysis products was minimal, but where the plant was grown had a strong influence on the pyrolysis products of the feedstock. Significant differences because of species variation could also be shown from the pyrolysis products of various biomass feedstocks. The influence of storage time on biomass samples stored outside in the open could also be discerned from the pyrolysis products of the feedstocks. The differences noted in the pyrolysis products of the feedstocks were noted for samples which were significantly degraded during storage either through the action of microflora or weathering.

  12. Single-domain chemical, thermochemical and thermal remanences in a basaltic rock

    NASA Astrophysics Data System (ADS)

    Draeger, Ulrike; Prévot, Michel; Poidras, Thierry; Riisager, Janna

    2006-07-01

    Tiny basaltic samples containing finely grained titanomagnetite with Curie temperature less than 100°C were heated in air in weak field (25-100μT) at temperatures between 400°C and 560°C for times as long as 32 hr. Oxyexsolution of titanomagnetite resulted in the crystallization of interacting single domain particles with Curie point close to 540°C and the concomitant development of one of two types chemical remanence, depending upon thermal treatment: isothermal chemical remanence (CRM) or thermochemical remanence (TCRM), the latter acquired under the combined effects of chemical change and temperature decrease. CRM and TCRM acquired under various conditions were subjected to Thellier-type experiments. All these treatments were carried out using a vibrating sample thermomagnetometer allowing the continuous recording of magnetization and a very precise temperature control. All CRM-TRM and TCRM-TRM plots were found to be linear over almost the entire TRM blocking temperature range, whether pTRM checks are positive or not. An apparent strength of the acquisition field of CRM or TCRM could thus be obtained and divided by the actually applied field to obtain a ratio R, which is representative of the CRM/TRM or TCRM/TRM ratios over most of the unblocking/blocking temperature spectrum. For CRM, it is found that R is less than 1 and increases rapidly with acquisition temperature (0.36 +/- 0.07 at 400°C, 0.66 +/- 0.02 at 450°C, and 0.90 +/- 0.02 at 500°C), in qualitative agreement with expressions derived from the theory of non-interacting single domain grains. Thus, very large underestimate of geomagnetic field palaeostrength can occur when a natural CRM is not recognized as such and is believed to be a natural TRM. Palaeointensity data obtained from geological material prone to the development of secondary minerals, as for example baked contacts and volcanic glasses have, therefore, to be considered with caution. In an attempt to mimic deuteric oxyexsolution in

  13. Comparison of thermal and chemical treatments of ultrathin chitosan films

    NASA Astrophysics Data System (ADS)

    Murray, Chris; Dutcher, John

    2006-03-01

    Chitosan is a biodegradable polysaccharide derived from seashell waste products. The high water absorbency and biocompatibility of chitosan have enabled its use as a hydrogel in specialty biomedical applications. Chitosan can be dissolved in weakly acidic solutions enabling its use in applications such as films and gels, which can be converted into chitin by a chemical process known as acetylation. We present the results of several experiments in which changes in the thickness, index of refraction and molecular environment in response to changes in relative humidity for ultrathin films of chitosan are examined as a function of exposure to temperatures above 150 degrees Celsius. Measurements made by ellipsometry and FTIR spectroscopy indicate that changes in the thickness and index of refraction of the films are accompanied by a change in the infrared absorption spectra similar to that associated with acetylation, which is typically accomplished by exposure of chitosan to acetic anhydride. We believe that these changes are responsible for reduced equilibrium water content in the films at all relative humidity values studied, and may offer a simple method for converting chitosan into a chitin-like material.

  14. Thermal and Chemical Characterization of Non-Metallic Materials Using Coupled Thermogravimetric Analysis and Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Huff, Timothy L.

    2002-01-01

    Thermogravimetric analysis (TGA) is widely employed in the thermal characterization of non-metallic materials, yielding valuable information on decomposition characteristics of a sample over a wide temperature range. However, a potential wealth of chemical information is lost during the process, with the evolving gases generated during thermal decomposition escaping through the exhaust line. Fourier Transform-Infrared spectroscopy (FT-IR) is a powerful analytical technique for determining many chemical constituents while in any material state, in this application, the gas phase. By linking these two techniques, evolving gases generated during the TGA process are directed into an appropriately equipped infrared spectrometer for chemical speciation. Consequently, both thermal decomposition and chemical characterization of a material may be obtained in a single sample run. In practice, a heated transfer line is employed to connect the two instruments while a purge gas stream directs the evolving gases into the FT-IR. The purge gas can be either high purity air or an inert gas such as nitrogen to allow oxidative and pyrolytic processes to be examined, respectively. The FT-IR data is collected realtime, allowing continuous monitoring of chemical compositional changes over the course of thermal decomposition. Using this coupled technique, an array of diverse materials has been examined, including composites, plastics, rubber, fiberglass epoxy resins, polycarbonates, silicones, lubricants and fluorocarbon materials. The benefit of combining these two methodologies is of particular importance in the aerospace community, where newly developing materials have little available data with which to refer. By providing both thermal and chemical data simultaneously, a more definitive and comprehensive characterization of the material is possible. Additionally, this procedure has been found to be a viable screening technique for certain materials, with the generated data useful in

  15. Thermal and Chemical Characterization of Non-metallic Materials Using Coupled Thermogravimetric Analysis and Infrared Spectroscopy

    NASA Technical Reports Server (NTRS)

    Huff, Timothy L.; Griffin, Dennis E. (Technical Monitor)

    2001-01-01

    Thermogravimetric analysis (TGA) is widely employed in the thermal characterization of non-metallic materials, yielding valuable information on decomposition characteristics of a sample over a wide temperature range. However, a potential wealth of chemical information is lost during the process, with the evolving gases generated during thermal decomposition escaping through the exhaust line. Fourier Transform-Infrared spectroscopy (FT-IR) is a powerful analytical technique for determining many chemical constituents while in any material state, in this application, the gas phase. By linking these two techniques, evolving gases generated during the TGA process are directed into an appropriately equipped infrared spectrometer for chemical speciation. Consequently, both thermal decomposition and chemical characterization of a material may be obtained in a single sample run. In practice, a heated transfer line is employed to connect the two instruments while a purge gas stream directs the evolving gases into the FT-IR, The purge gas can be either high purity air or an inert gas such as nitrogen to allow oxidative and pyrolytic processes to be examined, respectively. The FT-IR data is collected real-time, allowing continuous monitoring of chemical compositional changes over the course of thermal decomposition. Using this coupled technique, an array of diverse materials has been examined, including composites, plastics, rubber, fiberglass epoxy resins, polycarbonates, silicones, lubricants and fluorocarbon materials. The benefit of combining these two methodologies is of particular importance in the aerospace community, where newly developing materials have little available data with which to refer. By providing both thermal and chemical data simultaneously, a more definitive and comprehensive characterization of the material is possible. Additionally, this procedure has been found to be a viable screening technique for certain materials, with the generated data useful in

  16. Effects of Rapid Thermal Annealing and Different Oxidants on the Properties of LaxAlyO Nanolaminate Films Deposited by Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Fei, Chenxi; Liu, Hongxia; Wang, Xing; Zhao, Lu; Zhao, Dongdong; Feng, Xingyao

    2017-03-01

    A comparative study of different sequences of two metal precursors [trimethylaluminum (TMA) and Tris(isopropylcyclopentadienyl) lanthanum (La(iPrCp)3)] for atomic layer deposition (ALD) lanthanum aluminum oxide (LaxAlyO) films is carried out. The percentage compositions of C and N impurity of LaxAlyO films were investigated using in situ X-ray photoelectron spectroscopy (XPS). The effects of different oxidants on the physical and chemical properties and electrical characteristics of LaxAlyO films are studied before and after annealing. Preliminary testing results indicate that the impurity level of LaxAlyO films grown with different oxidants can be well controlled before and after annealing. Analysis indicates the rapid thermal annealing (RTA) and kinds of oxidants have significant effects on the equivalent oxide thickness (EOT), dielectric constant, electrical properties, and stability of LaxAlyO films. Additionally, the change of chemical bond types of rapid thermal annealing effects on the properties of LaxAlyO films are grown with different oxidants also investigated by XPS.

  17. Effects of Rapid Thermal Annealing and Different Oxidants on the Properties of LaxAlyO Nanolaminate Films Deposited by Atomic Layer Deposition.

    PubMed

    Fei, Chenxi; Liu, Hongxia; Wang, Xing; Zhao, Lu; Zhao, Dongdong; Feng, Xingyao

    2017-12-01

    A comparative study of different sequences of two metal precursors [trimethylaluminum (TMA) and Tris(isopropylcyclopentadienyl) lanthanum (La((i)PrCp)3)] for atomic layer deposition (ALD) lanthanum aluminum oxide (LaxAlyO) films is carried out. The percentage compositions of C and N impurity of LaxAlyO films were investigated using in situ X-ray photoelectron spectroscopy (XPS). The effects of different oxidants on the physical and chemical properties and electrical characteristics of LaxAlyO films are studied before and after annealing. Preliminary testing results indicate that the impurity level of LaxAlyO films grown with different oxidants can be well controlled before and after annealing. Analysis indicates the rapid thermal annealing (RTA) and kinds of oxidants have significant effects on the equivalent oxide thickness (EOT), dielectric constant, electrical properties, and stability of LaxAlyO films. Additionally, the change of chemical bond types of rapid thermal annealing effects on the properties of LaxAlyO films are grown with different oxidants also investigated by XPS.

  18. Stomatal Control and Leaf Thermal and Hydraulic Capacitances under Rapid Environmental Fluctuations

    PubMed Central

    Schymanski, Stanislaus J.; Or, Dani; Zwieniecki, Maciej

    2013-01-01

    Leaves within a canopy may experience rapid and extreme fluctuations in ambient conditions. A shaded leaf, for example, may become exposed to an order of magnitude increase in solar radiation within a few seconds, due to sunflecks or canopy motions. Considering typical time scales for stomatal adjustments, (2 to 60 minutes), the gap between these two time scales raised the question whether leaves rely on their hydraulic and thermal capacitances for passive protection from hydraulic failure or over-heating until stomata have adjusted. We employed a physically based model to systematically study effects of short-term fluctuations in irradiance on leaf temperatures and transpiration rates. Considering typical amplitudes and time scales of such fluctuations, the importance of leaf heat and water capacities for avoiding damaging leaf temperatures and hydraulic failure were investigated. The results suggest that common leaf heat capacities are not sufficient to protect a non-transpiring leaf from over-heating during sunflecks of several minutes duration whereas transpirative cooling provides effective protection. A comparison of the simulated time scales for heat damage in the absence of evaporative cooling with observed stomatal response times suggested that stomata must be already open before arrival of a sunfleck to avoid over-heating to critical leaf temperatures. This is consistent with measured stomatal conductances in shaded leaves and has implications for water use efficiency of deep canopy leaves and vulnerability to heat damage during drought. Our results also suggest that typical leaf water contents could sustain several minutes of evaporative cooling during a sunfleck without increasing the xylem water supply and thus risking embolism. We thus submit that shaded leaves rely on hydraulic capacitance and evaporative cooling to avoid over-heating and hydraulic failure during exposure to typical sunflecks, whereas thermal capacitance provides limited protection

  19. Stomatal control and leaf thermal and hydraulic capacitances under rapid environmental fluctuations.

    PubMed

    Schymanski, Stanislaus J; Or, Dani; Zwieniecki, Maciej

    2013-01-01

    Leaves within a canopy may experience rapid and extreme fluctuations in ambient conditions. A shaded leaf, for example, may become exposed to an order of magnitude increase in solar radiation within a few seconds, due to sunflecks or canopy motions. Considering typical time scales for stomatal adjustments, (2 to 60 minutes), the gap between these two time scales raised the question whether leaves rely on their hydraulic and thermal capacitances for passive protection from hydraulic failure or over-heating until stomata have adjusted. We employed a physically based model to systematically study effects of short-term fluctuations in irradiance on leaf temperatures and transpiration rates. Considering typical amplitudes and time scales of such fluctuations, the importance of leaf heat and water capacities for avoiding damaging leaf temperatures and hydraulic failure were investigated. The results suggest that common leaf heat capacities are not sufficient to protect a non-transpiring leaf from over-heating during sunflecks of several minutes duration whereas transpirative cooling provides effective protection. A comparison of the simulated time scales for heat damage in the absence of evaporative cooling with observed stomatal response times suggested that stomata must be already open before arrival of a sunfleck to avoid over-heating to critical leaf temperatures. This is consistent with measured stomatal conductances in shaded leaves and has implications for water use efficiency of deep canopy leaves and vulnerability to heat damage during drought. Our results also suggest that typical leaf water contents could sustain several minutes of evaporative cooling during a sunfleck without increasing the xylem water supply and thus risking embolism. We thus submit that shaded leaves rely on hydraulic capacitance and evaporative cooling to avoid over-heating and hydraulic failure during exposure to typical sunflecks, whereas thermal capacitance provides limited protection

  20. Electrical and thermal conductivities of rapidly crystallized Cu-Zr alloys: The effect of anharmonicity

    NASA Astrophysics Data System (ADS)

    Uporov, S.; Bykov, V.; Estemirova, S.

    2016-10-01

    We present a comprehensive study of electrical and thermal conductivities, specific heat and magnetic susceptibility of rapidly crystallized Cu100-xZrx (x = 20-90) alloys. X-ray diffraction analysis has revealed that all the prepared compositions had strongly textured and distorted crystal structures. Different monoclinic and other non-equilibrium phases were detected in the case of glass-forming samples, whereas the alloys without a tendency to form glassy state show almost equilibrium phase content. Metallic type of electrical conductivity and the Kondo anomaly were observed for all the examined samples. It was found that the electrical resistance data cannot be adequately described within the standard Bloch-Grüneisen theory. We use the Debye characteristic temperature as a linear function to fit the electrical conductivity accurately. The composition dependence of the electron density of states at the Fermi level (DOS) has been extracted from room temperature magnetic susceptibility. We found that the glass-forming alloys are characterized by abnormally large values of DOS, which are comparable to those of glassy analogues. Noticeable anharmonic contribution in total specific heat has been revealed for all the studied compositions. In order to estimate the effect of anharmonicity in the system under consideration, we analyzed composition and temperature dependencies of the studied thermal characteristics related to the Grüneisen coefficient. Basing on the results obtained in this study we propose a phenomenological concept to explain abnormal behavior of physical properties of glass-forming Cu-Zr alloys within the standard solid state theory taking into account anharmonic effects.

  1. Chemical and thermal modulation of molecular motor activities

    NASA Astrophysics Data System (ADS)

    Hong, Weili

    Molecular motors of kinesin and dynein families are responsible for various intracellular activities, from long distance movement of organelles, vesicles, protein complexes, and mRNAs to powering mitotic processes. They can take nanometer steps using chemical energy from the hydrolysis of ATP (adenosine triphosphate), and their dysfunction is involved in many neurodegenerative diseases that require long distance transport of cargos. Here I report on the study of the properties of molecular motors at a single-molecule level using optical trappings. I first studied the inhibition properties of kinesin motors by marine natural compound adociasulfates. I showed that adociasulfates compete with microtubules for binding to kinesins and thus inhibit kinesins' activity. Although adociasulfates are a strong inhibitor for all kinesin members, they show a much higher inhibition effect for conventional kinesins than for mitotic kinesins. Thus adociasulfates can be used to specifically inhibit conventional kinesins. By comparing the inhibition of kinesins by two structurally similar adociasulfates, one can see that the negatively charged sulfate residue of adociasulfates can be replaced by other negative residues and thus make it possible for adociasulfate-derived compounds to be more cell permeable. Kinesins and dyneins move cargos towards opposite directions along a microtubule. Cargos with both kinesins and dyneins attached often move bidirectionally due to undergoing a tug-of-war between the oppositely moving kinesin and dynein motors. Here I studied the effect of temperature on microtubule-based kinesin and dynein motor transport. While kinesins' and dyneins' velocities are closely matched above 15 °C, below this temperature the dyneins' velocity decreases much faster than the kinesins'. The kinesins' and dyneins' forces do not measurably change with temperature. The results suggest that temperature has significant effects on bidirectional transport and can be used to

  2. Onset of thermal convection in rapidly rotating spheres and spheroids at very low Ekman number

    NASA Astrophysics Data System (ADS)

    Maffei, S.; Jackson, A.; Livermore, P. W.

    2016-12-01

    The flows in the fluid cores of rapidly rotating planetary bodies can be conveniently described as being invariant along the direction parallel to the rotation axis. This description, also referred to as columnar, is based on the quasi-geostrophic approximation and it holds for timescales longer than the rotation period as long as other forces acting on the fluid are of secondary importance with respect to rotation. A significant effort of the community is presently spent in the development of quasi-geostrophic numerical models of planetary cores, the final goal being to run numerical simulations in parameters regimes relevant for planetary dynamics. The development of such models has proven fundamentally challenging, especially when magnetic forces are present. Therefore, analytical solutions to simple dynamical problems will be of paramount importance for benchmarking purposes. We present an analytical and explicit solution to the problem of the columnar inertial modes in rapidly rotating sphere and spheroids in absence of viscosity. We find that the oblateness of the spheroid significantly alters the frequency of the low order inertial modes for high azimuthal wavenumbers. However the geometry of the flow is the same as for the spherical case. Excellent agreement with known 3-D solutions has been found. Typically, given the geometry of the columnar flows, the axial vorticity equation is assumed to be a valid description of the dynamics of quasi-geostrophic flows. Based on a recently developed projection technique, we found the axial vorticity equation to be appropriate only in the case of highly oblate spheroids. Our analytical solution can be used to calculate the critical Rayleigh number and the structure of the flow at the onset of thermal convection. We do so by following an asymptotic procedure already applied to the spherical case and for 3-D flows. Thanks to our new quasi-geostrophic solution and to the use of spectral strategies to solve the problem, we

  3. Thermal/chemical stability of ceramic cross flow filter materials

    SciTech Connect

    Alvin, M.A.; Bahovchin, D.M.; Lippert, T.E.; Tressler, R.E.; McNerney, K.B.

    1992-01-01

    Westinghouse has undertaken a two phase program to determine possible long-term, high temperature influence that advanced coal-based power system environments may have on the stability of the ceramic cross flow filter elements. During the past year, we have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100[degrees]C) under oxidizing conditions which contain gas phase alkali species. The alumina/mullite cross flow liter material that has consistently been used throughout the flow-through gas phase alkali testing segment of this program, consists of mullite rods or needles that are embedded within an amorphous phase which contains corundum (Al[sub 2]O[sub 3]) and anorthite (CaAl[sub 2]Si[sub 2]O[sub 8]). Due to the rapid cooling rate that was used to produce the alumina/mullite filter disc material from high fire, the matrix consists of 59.6 wt% mullite, 30.5 wt% amorphous, 5.1 wt% anorthite, and 4.8 wt% alumina. The relatively low, as-fabricated, hot strength of this material (841[plus minus]259 psi at 870[degrees]C) is a direct result of the high amorphous content which softens at temperatures of 870[degrees]C. Load versus deflection curves as a function of temperature indicate that this material is relatively brittle up to temperatures of 600[degrees]C. Both a loss of strength, as well as plastic deformation of the matrix occurs at [approximately]700[degrees]C. If cross flow filters are manufactured from an alumina/mullite matrix that contains an [approximately]30.5 wt% amorphous content, we suspect that the plastic nature of the glass phase could potentially serve as a substrate for fines collection during initial filter operation at 700[degrees]C. Similarly the plastic nature could potentially cause deformation of the liter under load.

  4. Thermal/chemical stability of ceramic cross flow filter materials

    SciTech Connect

    Alvin, M.A.; Bahovchin, D.M.; Lippert, T.E.; Tressler, R.E.; McNerney, K.B.

    1992-11-01

    Westinghouse has undertaken a two phase program to determine possible long-term, high temperature influence that advanced coal-based power system environments may have on the stability of the ceramic cross flow filter elements. During the past year, we have principally focused our efforts on developing an understanding of the stability of the alumina/mullite filter material at high temperature (i.e., 870, 980, and 1100{degrees}C) under oxidizing conditions which contain gas phase alkali species. The alumina/mullite cross flow liter material that has consistently been used throughout the flow-through gas phase alkali testing segment of this program, consists of mullite rods or needles that are embedded within an amorphous phase which contains corundum (Al{sub 2}O{sub 3}) and anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}). Due to the rapid cooling rate that was used to produce the alumina/mullite filter disc material from high fire, the matrix consists of 59.6 wt% mullite, 30.5 wt% amorphous, 5.1 wt% anorthite, and 4.8 wt% alumina. The relatively low, as-fabricated, hot strength of this material (841{plus_minus}259 psi at 870{degrees}C) is a direct result of the high amorphous content which softens at temperatures of 870{degrees}C. Load versus deflection curves as a function of temperature indicate that this material is relatively brittle up to temperatures of 600{degrees}C. Both a loss of strength, as well as plastic deformation of the matrix occurs at {approximately}700{degrees}C. If cross flow filters are manufactured from an alumina/mullite matrix that contains an {approximately}30.5 wt% amorphous content, we suspect that the plastic nature of the glass phase could potentially serve as a substrate for fines collection during initial filter operation at 700{degrees}C. Similarly the plastic nature could potentially cause deformation of the liter under load.

  5. Rapid thermal annealing of magnesium implanted GaAs-GaAIAs heterostructures experimental and simulated distributions

    NASA Astrophysics Data System (ADS)

    Ketata, K.; Debrie, R.; Ketata, M.

    1993-01-01

    The use of rapid thermal annealing (RTA) techniques to anneal ion implanted GaAs compounds is expected to have a significant impact on device technology. Due to the short duration of the heat treatment, the implanted impurities may be activated without significant diffusion. For heterojunction bipolar transistor (HBT) applications, high doses of p-type impurities are required to compensate the doping levels of N-GaAlAs emitter and n+ GaAs contact layers. Multi-implantations were chosen to maintain a flat profile down to the base layer. Energies of 30, 60, 150, and 340 keV with doses of 6 × 1013, 9 × 1013,6 × 1014, and 9 × 1014 cm-2, respectively, have been used. Annealing cycles with time durations of a few seconds and temperature in the range of 850 950°C are described. Electrical properties of the annealed samples have been investigated using an electrochemical measurement technique. It was found that hole concentrations as high as 4 × 1019 cm-3 and electrical activities near to 75 percent can be obtained. There is no evident indiffusion and no significant outdiffusion at the optimal annealing conditions. Simulation of multilayer implantations are also carried out by an accurate model available in TITAN 2D process simulator using Pearson IV laws and taking into account the diffusion effects on profile distribution caused by RTA. A first approximation using a simple model allows a rapid evaluation of the data fitting operation. In a second approach, concentration dependent diffusivity and the contribution of the electric field at the interface are covered to perform an improved data fitting of ion implanted and annealed dopant profiles. A comparative study shows a good agreement between experimental and simulated distributions.

  6. Neutralization of Aerosolized Bio-Agents by Filled Nanocomposite Materials through Thermal and Chemical Inactivation Mechanisms

    DTIC Science & Technology

    2016-06-01

    materials (FNMs) that are useful as energetic components while releasing highly potent biocidal combustion products. These materials were intended to...other formulation components . Beyond the material development and characterization scope, this study aimed at extensively testing the biocidal...Bio-agents by Filled Nanocomposite Materials through Thermal and Chemical Inactivation Mechanisms Distribution Statement A. Approved for public

  7. CAES 2014 Chemical Analyses of Thermal Wells and Springs in Southeastern Idaho

    DOE Data Explorer

    Baum, Jeffrey

    2014-03-10

    This dataset contains chemical analyses for thermal wells and springs in Southeastern Idaho. Data includes all major cations, major anions, pH, collection temperature, and some trace metals, These samples were collected in 2014 by the Center for Advanced Energy Studies (CAES), and are part of a continuous effort to analyze the geothermal potential of Southeastern Idaho.

  8. New class of thermosetting plastics has improved strength, thermal and chemical stability

    NASA Technical Reports Server (NTRS)

    Burns, E. A.; Dubrow, B.; Lubowitz, H. R.

    1967-01-01

    New class of thermosetting plastics has high hydrocarbon content, high stiffness, thermal stability, humidity resistance, and workability in the precured state. It is designated cyclized polydiene urethane, and is applicable as matrices to prepare chemically stable ablative materials for rocket nose cones of nozzles.

  9. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

    EPA Science Inventory

    ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

  10. Low-thrust chemical propulsion system propellant expulsion and thermal conditioning study. Executive summary

    NASA Technical Reports Server (NTRS)

    Merino, F.; Wakabayashi, I.; Pleasant, R. L.; Hill, M.

    1982-01-01

    Preferred techniques for providing abort pressurization and engine feed system net positive suction pressure (NPSP) for low thrust chemical propulsion systems (LTPS) were determined. A representative LTPS vehicle configuration is presented. Analysis tasks include: propellant heating analysis; pressurant requirements for abort propellant dump; and comparative analysis of pressurization techniques and thermal subcoolers.

  11. Purification process of natural graphite as anode for Li-ion batteries: chemical versus thermal

    NASA Astrophysics Data System (ADS)

    Zaghib, K.; Song, X.; Guerfi, A.; Rioux, R.; Kinoshita, K.

    The intercalation of Li ions in natural graphite that was purified by chemical and thermal processes was investigated. A new chemical process was developed that involved a mixed aqueous solution containing 30% H 2SO 4 and 30% NH xF y heated to 90 °C. The results of this process are compared to those obtained by heating the natural graphite from 1500 to 2400 °C in an inert environment (thermal process). The first-cycle coulombic efficiency of the purified natural graphite obtained by the chemical process is 91 and 84% after the thermal process at 2400 °C. Grinding the natural graphite before or after purification had no significant effect on electrochemical performance at low currents. However, grinding to a very small particle size before purification permitted optimization of the size distribution of the particles, which gives rise to a more homogenous electrode. The impurities in the graphite play a role as microabrasion agents during grinding which enhances its hardness and improves its mechanical properties. Grinding also modifies the particle morphology from a 2- to a 3-D structure (similar in shape to a potato). This potato-shaped natural graphite shows high reversible capacity at high current densities (about 90% at 1 C rate). Our analysis suggests that thermal processing is considerably more expensive than the chemical process to obtain purified natural graphite.

  12. ECO LOGIC INTERNATIONAL GAS-PHASE CHEMICAL REDUCTION PROCESS - THE THERMAL DESORPTION UNIT - APPLICATIONS ANALYSIS REPORT

    EPA Science Inventory

    ELI ECO Logic International, Inc.'s Thermal Desorption Unit (TDU) is specifically designed for use with Eco Logic's Gas Phase Chemical Reduction Process. The technology uses an externally heated bath of molten tin in a hydrogen atmosphere to desorb hazardous organic compounds fro...

  13. Magnetic field topology and chemical abundance distributions of the young, rapidly rotating, chemically peculiar star HR 5624

    NASA Astrophysics Data System (ADS)

    Kochukhov, O.; Silvester, J.; Bailey, J. D.; Landstreet, J. D.; Wade, G. A.

    2017-09-01

    Context. The young, rapidly rotating Bp star HR 5624 (HD 133880) shows an unusually strong non-sinusoidal variability of its longitudinal magnetic field. This behaviour was previously interpreted as the signature of an exceptionally strong, quadrupole-dominated surface magnetic field geometry. Aims: We studied the magnetic field structure and chemical abundance distributions of HR 5624 with the aim to verify the unusual quadrupolar nature of its magnetic field and to investigate correlations between the field topology and chemical spots. Methods: We analysed high-resolution, time series Stokes parameter spectra of HR 5624 with the help of a magnetic Doppler imaging inversion code based on detailed polarised radiative transfer modelling of the line profiles. Results: We refined the stellar parameters, revised the rotational period, and obtained new longitudinal magnetic field measurements. Our magnetic Doppler inversions reveal that the field structure of HR 5624 is considerably simpler and the field strength is much lower than proposed by previous studies. We find a maximum local field strength of 12 kG and a mean field strength of 4 kG, which is about a factor of three weaker than predicted by quadrupolar field models. Our model implies that overall large-scale field topology of HR 5624 is better described as a distorted, asymmetric dipole rather than an axisymmetric quadrupole. The chemical abundance maps of Mg, Si, Ti, Cr, Fe, and Nd obtained in our study are characterised by large-scale, high-contrast abundance patterns. These structures correlate weakly with the magnetic field geometry and, in particular, show no distinct element concentrations in the horizontal field regions predicted by theoretical atomic diffusion calculations. Conclusions: We conclude that the surface magnetic field topology of HR 5624 is not as unusual as previously proposed. Considering these results together with other recent magnetic mapping analyses of early-type stars suggests that

  14. Bentonite alteration due to thermal-hydro-chemical processes during the early thermal period in a nuclear waste repository

    SciTech Connect

    Xu, T.; Senger, R.; Finsterle, S.

    2011-02-01

    After closure of an underground nuclear waste repository, the decay of radionuclides will raise temperature in the repository, and the bentonite buffer will resaturate by water inflow from the surrounding host rock. The perturbations from these thermal and hydrological processes are expected to dissipate within hundreds to a few thousand years. Here, we investigate coupled thermal-hydro-chemical processes and their effects on the short-term performance of a potential nuclear waste repository located in a clay formation. Using a simplified geometric configuration and abstracted hydraulic parameters of the clayey formation, we examine geochemical processes, coupled with thermo-hydrologic phenomena, and potential changes in porosity near the waste container during the early thermal period. The developed models were used for evaluating the mineral alterations and potential changes in porosity of the buffer, which can affect the repository performance. The results indicate that mineral alteration and associated changes in porosity induced by early thermal and hydrological processes are relatively small and are expected to not significantly affect flow and transport properties. Chlorite precipitation was obtained in all simulation cases. A maximum of one percent volume fraction of chlorite could be formed, whose process may reduce swelling and sorption capacity of bentonite clay, affecting the performance of the repository. llitisation process was not obtained from the present simulations.

  15. An analysis of a charring ablator with thermal nonequilibrium, chemical kinetics, and mass transfer

    NASA Technical Reports Server (NTRS)

    Clark, R. K.

    1973-01-01

    The differential equations governing the transient response of a one-dimensional ablative thermal protection system are presented for thermal nonequilibrium between the pyrolysis gases and the char layer and with finite rate chemical reactions occurring. The system consists of three layers (the char layer, the uncharred layer, and an optical insulation layer) with concentrated heat sinks at the back surface and between the second and third layers. The equations are solved numerically by using a modified implicit finite difference scheme to obtain solutions for the thickness of the charred and uncharred layers, surface recession and pyrolysis rates, solid temperatures, porosity profiles, and profiles of pyrolysis-gas temperature, pressure, composition, and flow rate. Good agreement is obtained between numerical results and exact solutions for a number of simplified cases. The complete numerical analysis is used to obtain solutions for an ablative system subjected to a constant heating environment. Effects of thermal, chemical, and mass transfer processes are shown.

  16. Proteolysis approach without chemical modification for a simple and rapid analysis of disulfide bonds using thermostable protease-immobilized microreactors.

    PubMed

    Yamaguchi, Hiroshi; Miyazaki, Masaya; Maeda, Hideaki

    2010-08-01

    Disulfide bonds in proteins are important not only for the conformational stability of the protein but also for the regulation of oxidation-reduction in signal transduction. The conventional method for the assignment of disulfide bond by chemical cleavage and/or proteolysis is a time-consuming multi-step procedure. In this study, we report a simple and rapid analysis of disulfide bond from protein digests that were prepared by the thermostable protease-immobilized microreactors. The feasibility and performance of this approach were evaluated by digesting lysozyme and BSA at several temperatures. The proteins which stabilize their conformations by disulfide bonds were thermally denatured during proteolysis and were efficiently digested by the immobilized protease but not by free protease. The digests were directly analyzed by ESI-TOF MS without any purification or concentration step. All four disulfide bonds on lysozyme and 10 of 17 on BSA were assigned from the digests by the trypsin-immobilized microreactor at 50 degrees C. The procedure for proteolysis and the assignment were achieved within 2 h without any reduction and alkylation procedure. From the present results, the proteolysis approach by the thermostable protease-immobilized microreactor provides a strategy for the high-throughput analysis of disulfide bond in proteomics.

  17. Rapid Establishment of Chemical and Mechanical Properties During Lamellar Bone Formation

    SciTech Connect

    Busa,B.; Miller, L.; Rubin, C.; Qin, Y.; Judex, S.

    2005-01-01

    The development of prophylaxes and treatments of bone diseases that can effectively increase the strength of bone as a structure necessitates a better understanding of the time course by which chemical properties define the stiffness of the material during primary and secondary mineralization. It was hypothesized that these processes would be relatively slow in the actively growing skeleton. Seven-week-old Sprague-Dawley female rats (n = 8) were injected with multiple fluorochrome labels over a time span of 3 weeks and killed. Chemical and mechanical properties of the tibial mid-diaphysis were spatially characterized between the endocortical and periosteal surface by in situ infrared microspectroscopy and nanoindentation. The phosphate-to-protein ratio of bone 2-6 days old was 20% smaller at the periosteal surface and 22% smaller at the endocortical surface (P < 0.05 each) compared to older intracortical regions. The ratios of carbonate to protein, crystallinity, type A/type B carbonate, collagen cross-linking, and bone elastic modulus did not differ significantly between bone 2-6, 10-14, and 8-22 days old and intracortical regions. Intracortical properties of 10-week-old rats, except for the carbonate-to-protein ratio which was 23% smaller (P < 0.01), were not significantly different from intracortical matrix properties of young adult rats (5 months, n = 4). Spatially, the phosphate-to-protein ratio (R{sup 2} = 0.33) and the phosphate-to-carbonate ratio (R{sup 2} = 0.55) were significantly correlated with bone material stiffness, while the combination of all chemical parameters raised the R{sup 2} value to 0.83. These data indicate that lamellar bone has the ability to quickly establish its mechanical and chemical tissue properties during primary and secondary mineralization even when the skeleton experiences rapid growth.

  18. Atmospheric Pressure-Thermal Desorption (AP-TD)/Electrospray Ionization-Mass Spectrometry for the Rapid Analysis of Bacillus Spores

    USDA-ARS?s Scientific Manuscript database

    A technique is described where an atmospheric pressure-thermal desorption (AP-TD) device and electrospray ionization (ESI)-mass spectrometry are coupled and used for the rapid analysis of Bacillus spores in complex matrices. The resulting AP-TD/ESI-MS technique combines the generation of volatile co...

  19. Rapid and Adaptable Measurement of Protein Thermal Stability by Differential Scanning Fluorimetry: Updating a Common Biochemical Laboratory Experiment

    ERIC Educational Resources Information Center

    Johnson, R. Jeremy; Savas, Christopher J.; Kartje, Zachary; Hoops, Geoffrey C.

    2014-01-01

    Measurement of protein denaturation and protein folding is a common laboratory technique used in undergraduate biochemistry laboratories. Differential scanning fluorimetry (DSF) provides a rapid, sensitive, and general method for measuring protein thermal stability in an undergraduate biochemistry laboratory. In this method, the thermal…

  20. Rapid and Adaptable Measurement of Protein Thermal Stability by Differential Scanning Fluorimetry: Updating a Common Biochemical Laboratory Experiment

    ERIC Educational Resources Information Center

    Johnson, R. Jeremy; Savas, Christopher J.; Kartje, Zachary; Hoops, Geoffrey C.

    2014-01-01

    Measurement of protein denaturation and protein folding is a common laboratory technique used in undergraduate biochemistry laboratories. Differential scanning fluorimetry (DSF) provides a rapid, sensitive, and general method for measuring protein thermal stability in an undergraduate biochemistry laboratory. In this method, the thermal…

  1. Efficacy of amniotic membrane patching for acute chemical and thermal ocular burns.

    PubMed

    Prabhasawat, Pinnita; Tesavibul, Nattaporn; Prakairungthong, Nauljira; Booranapong, Wipawee

    2007-02-01

    To study the efficacy of amniotic membrane patching (AMP) for acute chemical and thermal ocular burns and compare the results with a control group. Fifteen patients (21 eyes) with acute ocular burn severity grading of II to IV were retrospectively reviewed. Thirteen eyes were treated with preserved AMP while eight eyes were treated with conventional treatment. Outcomes and complications were evaluated and compared between eyes in the AMP group and the control group with the same severity of burn. In the AMP group, the mean age was 36.9 +/- 11.7 years (range, 20-58). The mean follow-up time was 8.0 +/- 6.8 months (range, 1-20). Complete epithelialization was achieved in 69.2% (9/13 eyes) in total, 100% (5/5 eyes), 100% (3/3 eyes) and 20% (1/5 eyes) in grade II, III and IV respectively. Mean epithelial healing time in the AMP group was 10.4 +/- 5.8 days (range, 4-20). Comparison of grade 2 and 3 burns showed that the AMP group in which patching was performed within 5 days resulted in faster epithelial healing, less corneal haze and limbal deficiency than in the group in which patching was performed after 5 days, and the control group (mean epithelial defect 7.0 +/- 2.0, 19.5 +/- 0.7, 9.9 +/- 10.8 days respectively). Adjunctive treatment of ocular burns with AMP promoted rapid epithelial healing and reduced corneal complication. Surgery performed in the early stage tended to yield a better outcome.

  2. Rapid and sustained surface ocean acidification during the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Penman, Donald E.; Hönisch, Bärbel; Zeebe, Richard E.; Thomas, Ellen; Zachos, James C.

    2014-05-01

    The Paleocene-Eocene Thermal Maximum (PETM) has been associated with the release of several thousands of petagrams of carbon (Pg C) as methane and/or carbon dioxide into the ocean-atmosphere system within ~10 kyr, on the basis of the co-occurrence of a carbon isotope excursion (CIE), widespread dissolution of deep sea carbonates, and global warming. In theory, this rapid carbon release should have severely acidified the surface ocean, though no geochemical evidence has yet been presented. Using boron-based proxies for surface ocean carbonate chemistry, we present the first observational evidence for a drop in the pH of surface and thermocline seawater during the PETM. Planktic foraminifers from a drill site in the North Pacific (Ocean Drilling Program Site 1209) show a ~0.8‰ decrease in boron isotopic composition (δ11B) at the onset of the event, along with a 30-40% reduction in shell B/Ca. Similar trends in δ11B are present in two lower-resolution records from the South Atlantic and Equatorial Pacific. These observations are consistent with significant, global acidification of the surface ocean lasting at least 70 kyr and requiring sustained carbon release. The anomalies in the B records are consistent with an initial surface pH drop of ~0.3 units, at the upper range of model-based estimates of acidification.

  3. Facile synthesis of few-layer graphene with a controllable thickness using rapid thermal annealing.

    PubMed

    Chu, Jae Hwan; Kwak, Jinsung; Kwon, Tae-Yang; Park, Soon-Dong; Go, Heungseok; Kim, Sung Youb; Park, Kibog; Kang, Seoktae; Kwon, Soon-Yong

    2012-03-01

    Few-layer graphene films with a controllable thickness were grown on a nickel surface by rapid thermal annealing (RTA) under vacuum. The instability of nickel films in air facilitates the spontaneous formation of ultrathin (<2-3 nm) carbon- and oxygen-containing compounds on a nickel surface; thus, the high-temperature annealing of the nickel samples without the introduction of intentional carbon-containing precursors results in the formation of graphene films. From annealing temperature and ambient studies during RTA, it was found that the evaporation of oxygen atoms from the surface is the dominant factor affecting the formation of graphene films. The thickness of the graphene layers is strongly dependent on the RTA temperature and time, and the resulting films have a limited thickness (<2 nm), even for an extended RTA time. The transferred films have a low sheet resistance of ~0.9 ± 0.4 kΩ/sq, with ~94% ± 2% optical transparency, making them useful for applications as flexible transparent conductors.

  4. Nano-Welding of Ag Nanowires Using Rapid Thermal Annealing for Transparent Conductive Films.

    PubMed

    Oh, Jong Sik; Oh, Ji Soo; Shin, Jae Hee; Yeom, Geun Young; Kim, Kyong Nam

    2015-11-01

    Ag nanowire (NW) films obtained by the spraying the Ag NWs on the substrates were nano-welded by rapid thermal annealing (RTA) process and the effect of RTA process on the change of sheet resistance and optical transmittance of the Ag NW films was investigated. The increased number of Ag NW sprays on the substrate decreased the sheet resistance but also decreased the optical transmittance. By the annealing for 60 sec in a nitrogen environment to 225-250 degrees C, the sheet resistance of Ag NW film could be decreased to about 50%, even though it was accompanied by the slight decrease of optical transmittance less than 5%. The decrease of sheet resistance was related to the nano-welding of the Ag NW junctions and the slight decrease of optical transmittance was related local melting of the Ag NWs and spreading on the substrate surface. Through the nano-welding by RTA process, the Ag NW film with the sheet resistance of -20 Ω/sq. and the optical transmittance of 93% could be obtained.

  5. Rapidly Thermal Annealed Si-Doped In2O3 Films for Organic Photovoltaics.

    PubMed

    Lee, Hye-Min; Kim, Han-Ki

    2015-10-01

    We report the electrical, optical, and structural properties of Si-doped In2O3 (ISO) films prepared using co-sputtering system with multi cathode guns for use in organic photovoltaics (OPVs). We investigated the effect of Si doping power on the electrical, optical, and structural properties of ISO film that was rapidly thermally annealed at a temperature of 400 °C. Due to the high Lewis acid strength (8.096) of the Si dopant, the ISO films showed high mobility and low resistivity despite the low Si doping concentration. Low resistivity of the annealed ISO films indicated that Si(4+) acts as an effective dopant of an In2O3 matrix by substitution with the In(3+) site. At a Si doping power of 50 W, ISO film showed a sheet resistance of 19.7 Ohm/square and optical transparency of 76.7%, which are acceptable values for fabrication of OPVs. Successful operation of OPV cells fabricated on transparent ISO film indicates that ISO is a promising high mobility transparent electrode material and alternative to conventional ITO films.

  6. Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing

    SciTech Connect

    Doshi, P.; Rohatgi, A.; Ropp, M.; Chen, Z.; Ruby, D.; Meier, D.L.

    1995-01-01

    Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J{sub 0}), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J{sub 0}.

  7. Rapid Thermal Annealing for Solution Synthesis of Transparent Conducting Aluminum Zinc Oxide Thin Films

    NASA Astrophysics Data System (ADS)

    Ullah, Sana; De Matteis, Fabio; Davoli, Ivan

    2017-07-01

    Transparent conducting oxide films with optimized dopant molar ratio have been prepared with limited pre- and postdeposition annealing duration of 10 min. Multiple aluminum zinc oxide (AZO) layers were spin-coated on ordinary glass substrates. The predeposition consolidation temperature and dopant molar ratio were optimized for electrical conductivity and optical transparency. Next, a group of films were deposited on Corning glass substrates from precursor solutions with the optimized dopant ratio, followed by postdeposition rapid thermal annealing (RTA) at different temperatures and in controlled environments. The lowest resistivity of 10.1 × 10-3 Ω cm was obtained for films receiving RTA at 600°C for 10 min each in vacuum then in N2-5%H2 environment, while resistivity of 20.3 × 10-3 Ω cm was obtained for films subjected to RTA directly in N2-5%H2. Optical measurements revealed average total transmittance of about 85% in the visible region. A direct allowed transition bandgap was determined based on the absorption edge with a value slightly above 3.0 eV, within the typical range for semiconductors. RTA resulted in desorption of oxygen with enhanced carrier concentration and crystallinity, which increased the carrier mobility with decreased bulk resistivity while maintaining the required optical transparency.

  8. Copper silicide formation by rapid thermal processing and induced room-temperature Si oxide growth

    NASA Astrophysics Data System (ADS)

    Setton, M.; Van der Spiegel, J.; Rothman, B.

    1990-07-01

    The growth of copper silicide has been studied by rapid thermal processing (RTP) of 500 Å of Cu on Si substrates. Interaction between the diffusing metal and Si starts at 250-300 °C. Annealing at higher temperatures yields complete silicidation to Cu3Si. This leads to strong modifications of the Auger line shapes of both Si and Cu. A plasmon peak located 20 eV below the main peak is the fingerprint in the Cu spectrum. Strong features at 80, 85.6, 89.2, and 93.2 eV as well as a 1 eV shift of the 90.4 eV peak appear in the Si L2,3VV spectrum. Whether for Cu films annealed in nitrogen or in vacuum, exposure of the silicide to air results in the growth of silicon oxide at room temperature and continues until the silicide layer is totally converted. This repeatable and controllable oxidation of silicon is accompanied by changes in resistivity and color reflecting the extent of the process. For Cu/CoSi2/Si structures, the cobalt silicide acts as a transport medium for the growth of the copper silicide and also serves as a cap preventing the oxidation of the final CoSi2/Cu3Si/Si contacts

  9. Analysis of recombination mechanisms in heterojunction silicon solar cells with rapid thermally annealed thin film emitters

    NASA Astrophysics Data System (ADS)

    Baldus-Jeursen, C.; Tarighat, R. S.; Sivoththaman, S.

    2017-05-01

    A new family of silicon (Si) wafer heterojunction solar cells fabricated by solid phase crystallization of PECVD amorphous silicon emitters by rapid thermal annealing (RTA) has been analyzed in order to understand the dominant recombination mechanisms. Solar cells fabricated with a broad RTA temperature range of 600-1000 °C were characterized through quantum efficiency, illuminated I-V, and capacitance-voltage measurements. Using the experimental data and theoretical considerations, the influence of carrier recombination in the quasi-neutral and space charge zones as well as at the heterojunction interface were studied. It is established that the carrier recombination in the quasi-neutral base region in the p-type Si substrate predominantly limits the device open circuit voltage. The analysis also showed that the interface recombination velocities at the heterojunction were less than 100 cm s-1. It is also qualitatively established that a post-fabrication forming gas anneal reduces the defect density at the hetero-interface.

  10. Formation of shallow junctions during rapid thermal processing from electron-beam deposited boron sources

    SciTech Connect

    Zagozdzon-Wosik, W.; Korablev, K.; Rusakova, I.; Wolfe, J.C.; Simons, D.; Chi, P.; Shi, J.H.

    1996-09-01

    Diffusion via rapid thermal processing (RTP) has been investigated for fabrication of shallow p-type layers doped with boron. The authors used dopant sources deposited by electron beam evaporation in the form of thin boron layers with or without in situ deposited silicon capping films. The deposition process is compatible with the resist mask due to low temperatures and poor step coverage, which facilitate dopant removal via a lift-off process. Sheet resistance measurements together with secondary ion mass spectroscopy and spreading resistance profiling analyses indicate that doping efficiency is high for both types of sources in the temperature range of 900 to 1,050 C for 10 to 30 s. Full dopant activation in the silicon substrate, except for the surface region, has been recorded for all process conditions. High surface concentrations observed in the processed samples were attributed to a residual boron layer. Oxidation during doping via RTP results in diffusion enhancement and in consumption of the boron source. Results of cross-sectional transmission electron microscopy (TEM) analyses confirm fast oxide growth rates during the diffusion processes in an oxygen ambient. No defects within the doped layers have been found for the process conditions used in the experiments.

  11. Enhanced UV photosensitivity from rapid thermal annealed vertically aligned ZnO nanowires

    PubMed Central

    2011-01-01

    We report on the major improvement in UV photosensitivity and faster photoresponse from vertically aligned ZnO nanowires (NWs) by means of rapid thermal annealing (RTA). The ZnO NWs were grown by vapor-liquid-solid method and subsequently RTA treated at 700°C and 800°C for 120 s. The UV photosensitivity (photo-to-dark current ratio) is 4.5 × 103 for the as-grown NWs and after RTA treatment it is enhanced by a factor of five. The photocurrent (PC) spectra of the as-grown and RTA-treated NWs show a strong peak in the UV region and two other relatively weak peaks in the visible region. The photoresponse measurement shows a bi-exponential growth and bi-exponential decay of the PC from as-grown as well as RTA-treated ZnO NWs. The growth and decay time constants are reduced after the RTA treatment indicating a faster photoresponse. The dark current-voltage characteristics clearly show the presence of surface defects-related trap centers on the as-grown ZnO NWs and after RTA treatment it is significantly reduced. The RTA processing diminishes the surface defect-related trap centers and modifies the surface of the ZnO NWs, resulting in enhanced PC and faster photoresponse. These results demonstrated the effectiveness of RTA processing for achieving improved photosensitivity of ZnO NWs. PMID:21859456

  12. Rapid carbon sequestration at the termination of the Palaeocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Bowen, Gabriel J.; Zachos, James C.

    2010-12-01

    The Palaeocene-Eocene Thermal Maximum (PETM), an approximately 170,000-year-long period of global warming about 56 million years ago, has been attributed to the release of thousands of petagrams of reduced carbon into the ocean, atmosphere and biosphere. However, the fate of this excess carbon at the end of the event is poorly constrained: drawdown of atmospheric carbon dioxide has been attributed to an increase in the weathering of silicates or to increased rates of organic carbon burial. Here we develop constraints on the rate of carbon drawdown based on rates of carbon isotope change in well-dated marine and terrestrial sediments spanning the event. We find that the rate of recovery is an order of magnitude more rapid than that expected for carbon drawdown by silicate weathering alone. Unless existing estimates of carbon stocks and cycling during this time are widely inaccurate, our results imply that more than 2,000Pg of carbon were sequestered as organic carbon over 30,000-40,000years at the end of the PETM. We suggest that the accelerated sequestration of organic carbon could reflect the regrowth of carbon stocks in the biosphere or shallow lithosphere that were released at the onset of the event.

  13. Defect reduction in MBE-grown AlN by multicycle rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Greenlee, Jordan D.; Gunning, Brendan; Feigelson, Boris N.; Anderson, Travis J.; Koehler, Andrew D.; Hobart, Karl D.; Kub, Francis J.; Doolittle, W. Alan

    2016-01-01

    Multicycle rapid thermal annealing (MRTA) is shown to reduce the defect density of molecular beam epitaxially grown AlN films. No damage to the AlN surface occurred after performing the MRTA process at 1520°C. However, the individual grain structure was altered, with the emergence of step edges. This change in grain structure and diffusion of AlN resulted in an improvement in the crystalline structure. The Raman E2 linewidth decreased, confirming an improvement in crystal quality. The optical band edge of the AlN maintained the expected value of 6.2 eV throughout MRTA annealing, and the band edge sharpened after MRTA annealing at increased temperatures, providing further evidence of crystalline improvement. X-ray diffraction shows a substantial improvement in the (002) and (102) rocking curve FWHM for both the 1400 and 1520°C MRTA annealing conditions compared to the as-grown films, indicating that the screw and edge type dislocation densities decreased. Overall, the MRTA post-growth annealing of AlN lowers defect density, and thus will be a key step to improving optoelectronic and power electronic devices. [Figure not available: see fulltext.

  14. Rapid thermal processing chamber for in-situ x-ray diffraction

    SciTech Connect

    Ahmad, Md. Imteyaz; Van Campen, Douglas G.; Yu, Jiafan; Pool, Vanessa L.; Van Hest, Maikel F. A. M.; Toney, Michael F.; Fields, Jeremy D.; Parilla, Philip A.; Ginley, David S.

    2015-01-15

    Rapid thermal processing (RTP) is widely used for processing a variety of materials, including electronics and photovoltaics. Presently, optimization of RTP is done primarily based on ex-situ studies. As a consequence, the precise reaction pathways and phase progression during the RTP remain unclear. More awareness of the reaction pathways would better enable process optimization and foster increased adoption of RTP, which offers numerous advantages for synthesis of a broad range of materials systems. To achieve this, we have designed and developed a RTP instrument that enables real-time collection of X-ray diffraction data with intervals as short as 100 ms, while heating with ramp rates up to 100 °Cs{sup −1}, and with a maximum operating temperature of 1200 °C. The system is portable and can be installed on a synchrotron beamline. The unique capabilities of this instrument are demonstrated with in-situ characterization of a Bi{sub 2}O{sub 3}-SiO{sub 2} glass frit obtained during heating with ramp rates 5 °C s{sup −1} and 100 °C s{sup −1}, revealing numerous phase changes.

  15. Depth profiles of oxygen precipitates in nitride-coated silicon wafers subjected to rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Voronkov, V. V.; Falster, R.; Kim, TaeHyeong; Park, SoonSung; Torack, T.

    2013-07-01

    Silicon wafers, coated with a silicon nitride layer and subjected to high temperature Rapid Thermal Annealing (RTA) in Ar, show—upon a subsequent two-step precipitation anneal cycle (such as 800 °C + 1000 °C)—peculiar depth profiles of oxygen precipitate densities. Some profiles are sharply peaked near the wafer surface, sometimes with a zero bulk density. Other profiles are uniform in depth. The maximum density is always the same. These profiles are well reproduced by simulations assuming that precipitation starts from a uniformly distributed small oxide plates originated from RTA step and composed of oxygen atoms and vacancies ("VO2 plates"). During the first step of the precipitation anneal, an oxide layer propagates around this core plate by a process of oxygen attachment, meaning that an oxygen-only ring-shaped plate emerges around the original plate. These rings, depending on their size, then either dissolve or grow during the second part of the anneal leading to a rich variety of density profiles.

  16. Lock-in thermography as a rapid and reproducible thermal characterization method for magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Lemal, Philipp; Geers, Christoph; Monnier, Christophe A.; Crippa, Federica; Daum, Leopold; Urban, Dominic A.; Rothen-Rutishauser, Barbara; Bonmarin, Mathias; Petri-Fink, Alke; Moore, Thomas L.

    2017-04-01

    Lock-in thermography (LIT) is a sensitive imaging technique generally used in engineering and materials science (e.g. detecting defects in composite materials). However, it has recently been expanded for investigating the heating power of nanomaterials, such as superparamagnetic iron oxide nanoparticles (SPIONs). Here we implement LIT as a rapid and reproducible method that can evaluate the heating potential of various sizes of SPIONs under an alternating magnetic field (AMF), as well as the limits of detection for each particle size. SPIONs were synthesized via thermal decomposition and stabilized in water via a ligand transfer process. Thermographic measurements of SPIONs were made by stimulating particles of varying sizes and increasing concentrations under an AMF. Furthermore, a commercially available SPION sample was included as an external reference. While the size dependent heating efficiency of SPIONs has been previously described, our objective was to probe the sensitivity limits of LIT. For certain size regimes it was possible to detect signals at concentrations as low as 0.1 mg Fe/mL. Measuring at different concentrations enabled a linear regression analysis and extrapolation of the limit of detection for different size nanoparticles.

  17. Dynamics of metal-induced crystallization of ultrathin Ge films by rapid thermal annealing

    SciTech Connect

    Liao, Yuanxun; Huang, Shujuan; Shrestha, Santosh; Conibeer, Gavin

    2015-12-07

    Though Ge crystallization has been widely studied, few works investigate metal-induced crystallization of ultrathin Ge films. For 2 nm Ge films in oxide matrix, crystallization becomes challenging due to easy oxidation and low mobility of Ge atoms. Introducing metal atoms may alleviate these problems, but the functions and the behaviours of metal atoms need to be clarified. This paper investigates the crystallization dynamics of a multilayer structure 1.9 nm Ge/0.5 nm Al/1.5 nm Al{sub 2}O{sub 3} under rapid thermal annealing (RTA). The functions of metal atoms, like effective anti-oxidation, downshifting Raman peaks, and incapability to decrease crystallization temperature, are found and explained. The metal behaviours, such as inter-diffusion and defect generation, are supported with direct evidences, Al-Ge nanobicrystals, and Al cluster in Ge atoms. With these understandings, a two-step RTA process achieves high-quality 2 nm nanocrystal Ge films with Raman peak at 298 cm{sup −1} of FWHM 10.3 cm{sup −1} and atomic smooth interfaces.

  18. Method and apparatus for obtaining enhanced production rate of thermal chemical reactions

    DOEpatents

    Tonkovich, Anna Lee Y [Pasco, WA; Wang, Yong [Richland, WA; Wegeng, Robert S [Richland, WA; Gao, Yufei [Kennewick, WA

    2003-04-01

    The present invention is a method and apparatus (vessel) for providing a heat transfer rate from a reaction chamber through a wall to a heat transfer chamber substantially matching a local heat transfer rate of a catalytic thermal chemical reaction. The key to the invention is a thermal distance defined on a cross sectional plane through the vessel inclusive of a heat transfer chamber, reaction chamber and a wall between the chambers. The cross sectional plane is perpendicular to a bulk flow direction of the reactant stream, and the thermal distance is a distance between a coolest position and a hottest position on the cross sectional plane. The thermal distance is of a length wherein the heat transfer rate from the reaction chamber to the heat transfer chamber substantially matches the local heat transfer rate.

  19. Thermal expansion of laminated, woven, continuous ceramic fiber/chemical-vapor-infiltrated silicon carbide matrix composites

    NASA Technical Reports Server (NTRS)

    Eckel, Andrew J.; Bradt, Richard C.

    1990-01-01

    Thermal expansions of three two-dimensional laminate, continuous fiber/chemical-vapor-infiltrated silicon carbide matrix composites reinforced with either FP-Alumina (alumina), Nextel (mullite), or Nicalon (Si-C-O-N) fibers are reported. Experimental thermal expansion coefficients parallel to a primary fiber orientation were comparable to values calculated by the conventional rule-of-mixtures formula, except for the alumina fiber composite. Hysteresis effects were also observed during repeated thermal cycling of that composite. Those features were attributed to reoccurring fiber/matrix separation related to the micromechanical stresses generated during temperature changes and caused by the large thermal expansion mismatch between the alumina fibers and the silicon carbide matrix.

  20. Geophysical inferences of thermal-chemical structures in the lower mantle

    NASA Technical Reports Server (NTRS)

    Yuen, D. A.; Cadek, O.; Chopelas, A.; Matyska, C.

    1993-01-01

    Lateral variations of the temperature field in the lower mantle have been reconstructed using new results in mineral physics and seismic tomographic data. We show that, with the application of high-pressure experimental values of thermal expansivity and of sound velocities, the slow seismic anomalies in the lower mantle under the Pacific and Africa can be converted into realistic-looking plume structures with large dimensions of 0(1000 km). The outer fringes of the plumes have an excess temperature of around 400 K. In the core of the plumes are found tonguelike structures with extremely high thermal anomalies. These values can exceed 1200 K and are too high to be explained on the basis of thermal anomalies alone. We suggest that these major plumes in the deep mantle may be driven by both thermal and chemical buoyancies or that enhanced conductive heat-transfer may be important there.

  1. Geophysical inferences of thermal-chemical structures in the lower mantle

    NASA Technical Reports Server (NTRS)

    Yuen, D. A.; Cadek, O.; Chopelas, A.; Matyska, C.

    1993-01-01

    Lateral variations of the temperature field in the lower mantle have been reconstructed using new results in mineral physics and seismic tomographic data. We show that, with the application of high-pressure experimental values of thermal expansivity and of sound velocities, the slow seismic anomalies in the lower mantle under the Pacific and Africa can be converted into realistic-looking plume structures with large dimensions of 0(1000 km). The outer fringes of the plumes have an excess temperature of around 400 K. In the core of the plumes are found tonguelike structures with extremely high thermal anomalies. These values can exceed 1200 K and are too high to be explained on the basis of thermal anomalies alone. We suggest that these major plumes in the deep mantle may be driven by both thermal and chemical buoyancies or that enhanced conductive heat-transfer may be important there.

  2. A rapid chemical method for lysing Arabidopsis cells for protein analysis.

    PubMed

    Tsugama, Daisuke; Liu, Shenkui; Takano, Tetsuo

    2011-07-15

    Protein extraction is a frequent procedure in biological research. For preparation of plant cell extracts, plant materials usually have to be ground and homogenized to physically break the robust cell wall, but this step is laborious and time-consuming when a large number of samples are handled at once. We developed a chemical method for lysing Arabidopsis cells without grinding. In this method, plants are boiled for just 10 minutes in a solution containing a Ca2+ chelator and detergent. Cell extracts prepared by this method were suitable for SDS-PAGE and immunoblot analysis. This method was also applicable to genomic DNA extraction for PCR analysis. Our method was applied to many other plant species, and worked well for some of them. Our method is rapid and economical, and allows many samples to be prepared simultaneously for protein analysis. Our method is useful not only for Arabidopsis research but also research on certain other species.

  3. Comparison of rapid methods for chemical analysis of milligram samples of ultrafine clays.

    USGS Publications Warehouse

    Rettig, S.L.; Marinenko, J.W.; Khoury, H.N.; Jones, B.F.

    1983-01-01

    Two rapid methods for the decomposition and chemical analysis of clays were adapted for use with 20-40mg size samples, typical amounts of ultrafine products (< 0.5 micrometer diameter) obtained from modern separation methods for clay minrals. The results of these methods were compared with those of 'classical' rock analyses. The two methods consisted of mixed lithium metaborate fusion and heated decomposition with HF in a closed vessel. The latter technique was modified to include subsequent evaporation with concentrated H2SO4 and re-solution in HCl, which reduced the interference of the fluoride ion in the determination of Al, Fe, Ca, Mg, Na, and K.-from Authors

  4. The influence of chemical chaperones on enzymatic activity under thermal and chemical stresses: common features and variation among diverse chemical families.

    PubMed

    Levy-Sakin, Michal; Berger, Or; Feibish, Nir; Sharon, Noa; Schnaider, Lee; Shmul, Guy; Amir, Yaniv; Buzhansky, Ludmila; Gazit, Ehud

    2014-01-01

    Molecular and chemical chaperones are key components of the two main mechanisms that ensure structural stability and activity under environmental stresses. Yet, chemical chaperones are often regarded only as osmolytes and their role beyond osmotic regulation is not fully understood. Here, we systematically studied a large group of chemical chaperones, representatives of diverse chemical families, for their protective influence under either thermal or chemical stresses. Consistent with previous studies, we observed that in spite of the structural similarity between sugars and sugar alcohols, they have an apparent difference in their protective potential. Our results support the notion that the protective activity is mediated by the solvent and the presence of water is essential. In the current work we revealed that i) polyols and sugars have a completely different profile of protective activity toward trifluoroethanol and thermal stress; ii) minor changes in solvent composition that do not affect enzyme activity, yet have a great effect on the ability of osmolytes to act as protectants and iii) increasing the number of active groups of carbohydrates makes them better protectants while increasing the number of active groups of methylamines does not, as revealed by attempts to synthesize de novo designed methylamines with multiple functional groups.

  5. The Influence of Chemical Chaperones on Enzymatic Activity under Thermal and Chemical Stresses: Common Features and Variation among Diverse Chemical Families

    PubMed Central

    Feibish, Nir; Sharon, Noa; Schnaider, Lee; Shmul, Guy; Amir, Yaniv; Buzhansky, Ludmila; Gazit, Ehud

    2014-01-01

    Molecular and chemical chaperones are key components of the two main mechanisms that ensure structural stability and activity under environmental stresses. Yet, chemical chaperones are often regarded only as osmolytes and their role beyond osmotic regulation is not fully understood. Here, we systematically studied a large group of chemical chaperones, representatives of diverse chemical families, for their protective influence under either thermal or chemical stresses. Consistent with previous studies, we observed that in spite of the structural similarity between sugars and sugar alcohols, they have an apparent difference in their protective potential. Our results support the notion that the protective activity is mediated by the solvent and the presence of water is essential. In the current work we revealed that i) polyols and sugars have a completely different profile of protective activity toward trifluoroethanol and thermal stress; ii) minor changes in solvent composition that do not affect enzyme activity, yet have a great effect on the ability of osmolytes to act as protectants and iii) increasing the number of active groups of carbohydrates makes them better protectants while increasing the number of active groups of methylamines does not, as revealed by attempts to synthesize de novo designed methylamines with multiple functional groups. PMID:24520396

  6. Chemical and isotopic data for water from thermal springs and wells of Oregon

    SciTech Connect

    Mariner, R.H.; Swanson, J.R.; Orris, G.J.; Presser, T.S.; Evans, W.C.

    1981-01-01

    The thermal springs of Oregon range in composition from dilute NaHCO/sub 3/ waters to moderately saline CO/sub 2/-charged NaCl-NaHCO/sub 3/ waters. Most of the thermal springs are located in southeastern or southcentral Oregon, with a few in northeastern Oregon and near the contact of the Western Cascades with the High Cascades. Thermal springs in the central and northern parts of the Cascades generally issue moderately saline NaCl waters. Farther south in the Cascades, the thermal waters are high in CO/sub 2/ as well as chloride. Most thermal springs in northeastern Oregon issue dilute NaHCO/sub 3/ waters of high pH (>8.5). These waters are similar to the thermal waters which issue from the Idaho batholith, farther east. Most of the remaining thermal waters are Na mixed-anion waters. Based on the chemical geothermometers, Mickey Srpings, Hot Borax Lake, Alvord Hot Springs, Neal Hot Springs, Vale Hot Springs, Crump Well, Hunters (Lakeview) Hot Springs, and perhaps some of the springs in the Cascades are associated with the highest temperature systems (>150/sup 0/C).

  7. Manipulating thermal conductance at metal-graphene contacts via chemical functionalization.

    PubMed

    Hopkins, Patrick E; Baraket, Mira; Barnat, Edward V; Beechem, Thomas E; Kearney, Sean P; Duda, John C; Robinson, Jeremy T; Walton, Scott G

    2012-02-08

    Graphene-based devices have garnered tremendous attention due to the unique physical properties arising from this purely two-dimensional carbon sheet leading to tremendous efficiency in the transport of thermal carriers (i.e., phonons). However, it is necessary for this two-dimensional material to be able to efficiently transport heat into the surrounding 3D device architecture in order to fully capitalize on its intrinsic transport capabilities. Therefore, the thermal boundary conductance at graphene interfaces is a critical parameter in the realization of graphene electronics and thermal solutions. In this work, we examine the role of chemical functionalization on the thermal boundary conductance across metal/graphene interfaces. Specifically, we metalize graphene that has been plasma functionalized and then measure the thermal boundary conductance at Al/graphene/SiO(2) contacts with time domain thermoreflectance. The addition of adsorbates to the graphene surfaces are shown to influence the cross plane thermal conductance; this behavior is attributed to changes in the bonding between the metal and the graphene, as both the phonon flux and the vibrational mismatch between the materials are each subject to the interfacial bond strength. These results demonstrate plasma-based functionalization of graphene surfaces is a viable approach to manipulate the thermal boundary conductance.

  8. Multiparametric fat–water separation method for fast chemical-shift imaging guidance of thermal therapies

    PubMed Central

    Lin, Jonathan S.; Hwang, Ken-Pin; Jackson, Edward F.; Hazle, John D.; Jason Stafford, R.; Taylor, Brian A.

    2013-01-01

    Purpose: A k-means-based classification algorithm is investigated to assess suitability for rapidly separating and classifying fat/water spectral peaks from a fast chemical shift imaging technique for magnetic resonance temperature imaging. Algorithm testing is performed in simulated mathematical phantoms and agar gel phantoms containing mixed fat/water regions. Methods: Proton resonance frequencies (PRFs), apparent spin-spin relaxation (T2*) times, and T1-weighted (T1-W) amplitude values were calculated for each voxel using a single-peak autoregressive moving average (ARMA) signal model. These parameters were then used as criteria for k-means sorting, with the results used to determine PRF ranges of each chemical species cluster for further classification. To detect the presence of secondary chemical species, spectral parameters were recalculated when needed using a two-peak ARMA signal model during the subsequent classification steps. Mathematical phantom simulations involved the modulation of signal-to-noise ratios (SNR), maximum PRF shift (MPS) values, analysis window sizes, and frequency expansion factor sizes in order to characterize the algorithm performance across a variety of conditions. In agar, images were collected on a 1.5T clinical MR scanner using acquisition parameters close to simulation, and algorithm performance was assessed by comparing classification results to manually segmented maps of the fat/water regions. Results: Performance was characterized quantitatively using the Dice Similarity Coefficient (DSC), sensitivity, and specificity. The simulated mathematical phantom experiments demonstrated good fat/water separation depending on conditions, specifically high SNR, moderate MPS value, small analysis window size, and low but nonzero frequency expansion factor size. Physical phantom results demonstrated good identification for both water (0.997 ± 0.001, 0.999 ± 0.001, and 0.986 ± 0.001 for DSC, sensitivity, and specificity, respectively

  9. Water-driven micromotors for rapid photocatalytic degradation of biological and chemical warfare agents.

    PubMed

    Li, Jinxing; Singh, Virendra V; Sattayasamitsathit, Sirilak; Orozco, Jahir; Kaufmann, Kevin; Dong, Renfeng; Gao, Wei; Jurado-Sanchez, Beatriz; Fedorak, Yuri; Wang, Joseph

    2014-11-25

    Threats of chemical and biological warfare agents (CBWA) represent a serious global concern and require rapid and efficient neutralization methods. We present a highly effective micromotor strategy for photocatalytic degradation of CBWA based on light-activated TiO2/Au/Mg microspheres that propel autonomously in natural water and obviate the need for external fuel, decontaminating reagent, or mechanical agitation. The activated TiO2/Au/Mg micromotors generate highly reactive oxygen species responsible for the efficient destruction of the cell membranes of the anthrax simulant Bacillus globigii spore, as well as rapid and complete in situ mineralization of the highly persistent organophosphate nerve agents into nonharmful products. The water-driven propulsion of the TiO2/Au/Mg micromotors facilitates efficient fluid transport and dispersion of the photogenerated reactive oxidative species and their interaction with the CBWA. Coupling of the photocatalytic surface of the micromotors and their autonomous water-driven propulsion thus leads to a reagent-free operation which holds a considerable promise for diverse "green" defense and environmental applications.

  10. A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters.

    PubMed

    Zhang, Shanqing; Li, Lihong; Zhao, Huijun

    2009-10-15

    A photoelectrochemical probe for rapid determination of chemical oxygen demand (COD) is developed using a nanostructured mixed-phase TiO2 photoanode, namely PeCOD probe. A UV-LED light source and a USB mircroelectrochemical station are powered and controlled by a laptop computer, which makes the probe portable for onsite COD analyses. The photoelectrochemical measurement of COD was optimized in terms of light intensity, applied bias, and pH. Under the optimized conditions, the net steady state currents originated from the oxidation of organic compounds were found to be directly proportional to COD concentrations. A practical detection limit of 0.2 ppm COD and a linear range of 0-120 ppm COD were achieved. The analytical method using the portable PeCOD probe has the advantages of being rapid, low cost, robust, user-friendly, and environmental friendly. It has been successfully applied to determine the COD values of the synthetic samples consisting of potassium hydrogen phthalate, D-glucose, glutamic acid, glutaric acid, succinic acid, and malonic acid, and real samples from various industries, such as bakery, oil and grease manufacturer, poultry, hotel, fine food factory, and fresh food producer, commercial bread manufacturer. Excellent agreement between the proposed method and the conventional COD method (dichromate) was achieved.

  11. Extractive Atmospheric Pressure Photoionization (EAPPI) Mass Spectrometry: Rapid Analysis of Chemicals in Complex Matrices

    NASA Astrophysics Data System (ADS)

    Liu, Chengyuan; Yang, Jiuzhong; Wang, Jian; Hu, Yonghua; Zhao, Wan; Zhou, Zhongyue; Qi, Fei; Pan, Yang

    2016-10-01

    Extractive atmospheric pressure photoionization (EAPPI) mass spectrometry was designed for rapid qualitative and quantitative analysis of chemicals in complex matrices. In this method, an ultrasonic nebulization system was applied to sample extraction, nebulization, and vaporization. Mixed with a gaseous dopant, vaporized analytes were ionized through ambient photon-induced ion-molecule reactions, and were mass-analyzed by a high resolution time-of-flight mass spectrometer (TOF-MS). After careful optimization and testing with pure sample solution, EAPPI was successfully applied to the fast screening of capsules, soil, natural products, and viscous compounds. Analysis was completed within a few seconds without the need for preseparation. Moreover, the quantification capability of EAPPI for matrices was evaluated by analyzing six polycyclic aromatic hydrocarbons (PAHs) in soil. The correlation coefficients ( R 2 ) for standard curves of all six PAHs were above 0.99, and the detection limits were in the range of 0.16-0.34 ng/mg. In addition, EAPPI could also be used to monitor organic chemical reactions in real time.

  12. Evaluation of a rapid physical-chemical method for the determination of extant soluble COD.

    PubMed

    Hu, Zhiqiang; Chandran, Kartik; Smets, Barth F; Grasso, Domenico

    2002-02-01

    Characterization of total chemical oxygen demand (COD) in wastewater is critical for accurate modeling of constituent biotransformation steps. We evaluated the accuracy and precision of a commonly used soluble COD determination technique (coagulation using ZnSO4 at pH 10.5) in relation to three other physical-chemical separation techniques: destabilization with a non-hydrolyzing trivalent cation (LaCl3), sequential filtration, and ultracentrifugation. Samples of deionized water and domestic wastewater were spiked with aliquots of synthetic soluble COD and recoveries using the different separation methods were compared. Although mechanisms of coagulation using LaCl3 and ZnSO4 are different, the mean COD recoveries using these methods were in close agreement. Further, sorption of soluble COD onto zinc hydroxide precipitate flocs appeared to be negligible. The two coagulation methods yielded statistically different (p = 0.05) soluble COD values when applied to nine independent wastewater samples (obtained on nine different days). but the difference was less than 10%. The COD quantified by the coagulation techniques corresponded most closely with the < 1,000 Da molecular weight fraction defined as "truly soluble COD". Centrifugation of wastewater samples amended with mercuric chloride (HgCl2) at 10 mg/L overestimated the soluble COD concentration. Our results confirm that coagulation using either ZnSO4 or LaCI3 is appropriate for the rapid determination of soluble COD fraction in wastewater matrices.

  13. Learning to Rapidly Re-Contact the Lost Plume in Chemical Plume Tracing

    PubMed Central

    Cao, Meng-Li; Meng, Qing-Hao; Wang, Jia-Ying; Luo, Bing; Jing, Ya-Qi; Ma, Shu-Gen

    2015-01-01

    Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT). In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF). In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF) method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS) method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF. PMID:25825974

  14. An oxazetidine amino acid for chemical protein synthesis by rapid, serine-forming ligations

    NASA Astrophysics Data System (ADS)

    Pusterla, Ivano; Bode, Jeffrey W.

    2015-08-01

    Amide-forming ligation reactions allow the chemical synthesis of proteins by the union of unprotected peptide segments, and enable the preparation of protein derivatives not accessible by expression or bioengineering approaches. The native chemical ligation (NCL) of thioesters and N-terminal cysteines is unquestionably the most successful approach, but is not ideal for all synthetic targets. Here we describe the synthesis of an Fmoc-protected oxazetidine amino acid for use in the α-ketoacid-hydroxylamine (KAHA) amide ligation. When incorporated at the N-terminus of a peptide segment, this four-membered cyclic hydroxylamine can be used for rapid serine-forming ligations with peptide α-ketoacids. This ligation operates at low concentration (100 μM-5 mM) and mild temperatures (20-25 °C). The utility of the reaction was demonstrated by the synthesis of S100A4, a 12 kDa calcium-binding protein not easily accessible by NCL or other amide-forming reactions due to its primary sequence and properties.

  15. Learning to rapidly re-contact the lost plume in chemical plume tracing.

    PubMed

    Cao, Meng-Li; Meng, Qing-Hao; Wang, Jia-Ying; Luo, Bing; Jing, Ya-Qi; Ma, Shu-Gen

    2015-03-27

    Maintaining contact between the robot and plume is significant in chemical plume tracing (CPT). In the time immediately following the loss of chemical detection during the process of CPT, Track-Out activities bias the robot heading relative to the upwind direction, expecting to rapidly re-contact the plume. To determine the bias angle used in the Track-Out activity, we propose an online instance-based reinforcement learning method, namely virtual trail following (VTF). In VTF, action-value is generalized from recently stored instances of successful Track-Out activities. We also propose a collaborative VTF (cVTF) method, in which multiple robots store their own instances, and learn from the stored instances, in the same database. The proposed VTF and cVTF methods are compared with biased upwind surge (BUS) method, in which all Track-Out activities utilize an offline optimized universal bias angle, in an indoor environment with three different airflow fields. With respect to our experimental conditions, VTF and cVTF show stronger adaptability to different airflow environments than BUS, and furthermore, cVTF yields higher success rates and time-efficiencies than VTF.

  16. Deposition of thermal and hot-wire chemical vapor deposition copper thin films on patterned substrates.

    PubMed

    Papadimitropoulos, G; Davazoglou, D

    2011-09-01

    In this work we study the hot-wire chemical vapor deposition (HWCVD) of copper films on blanket and patterned substrates at high filament temperatures. A vertical chemical vapor deposition reactor was used in which the chemical reactions were assisted by a tungsten filament heated at 650 degrees C. Hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) vapors were used, directly injected into the reactor with the aid of a liquid injection system using N2 as carrier gas. Copper thin films grown also by thermal and hot-wire CVD. The substrates used were oxidized silicon wafers on which trenches with dimensions of the order of 500 nm were formed and subsequently covered with LPCVD W. HWCVD copper thin films grown at filament temperature of 650 degrees C showed higher growth rates compared to the thermally ones. They also exhibited higher resistivities than thermal and HWCVD films grown at lower filament temperatures. Thermally grown Cu films have very uniform deposition leading to full coverage of the patterned substrates while the HWCVD films exhibited a tendency to vertical growth, thereby creating gaps and incomplete step coverage.

  17. Isotopic fractionation of the major elements of molten basalt by chemical and thermal diffusion

    NASA Astrophysics Data System (ADS)

    Richter, Frank M.; Watson, E. Bruce; Mendybaev, Ruslan; Dauphas, Nicolas; Georg, Bastian; Watkins, James; Valley, John

    2009-07-01

    Samples produced in piston cylinder experiments were used to document the thermal isotopic fractionation of all the major elements of basalt except for aluminum and the fractionation of iron isotopes by chemical diffusion between a natural basalt and rhyolite. The thermal isotopic fractionations are summarized in terms of a parameter Ω i defined as the fractionation in per mil per 100 °C per atomic mass units difference between the isotopes. For molten basalt we report ΩCa = 1.6, ΩFe = 1.1, ΩSi = 0.6, ΩO = 1.5. In an earlier paper we reported ΩMg = 3.6. These fractionations represent a steady state balance between thermal diffusion and chemical diffusion with the mass dependence of the thermal diffusion coefficient being significantly larger than the mass dependence of the chemical diffusion coefficients for isotopes of the same element. The iron isotopic measurements of the basalt-rhyolite diffusion couple showed significant fractionation that are parameterized in terms of a parameter βFe = 0.03 when the ratio of the diffusion coefficients D54 and D56 of 54Fe and 56Fe is expressed in terms of the atomic mass as D54/ D56 = (56/54). This value of βFe is smaller than what we had measured earlier for lithium, magnesium and calcium (i.e., βLi = 0.215, βCa = 0.05, βMg = 0.05) but still significant when one takes into account the high precision with which iron isotopic compositions can be measured (i.e., ±0.03‰) and that iron isotope fractionations at magmatic temperatures from other causes are extremely small. In a closing section we discuss technological and geological applications of isotopic fractionations driven by either or both chemical and thermal gradients.

  18. Characteristics of Lateral Heterogeneities with Thermal and Chemical Origins in the Pyrolitic Lower Mantle

    SciTech Connect

    Li, B.

    2009-01-01

    The relative changes between shear and compressional velocities (R{sub SP} = {partial_derivative} ln V{sub S}/{partial_derivative} ln V{sub P}), bulk sound and shear velocities (R{sub CS} = {partial_derivative} ln V{sub C}/{partial_derivative} ln V{sub S}), and density versus shear wave velocity (R{sub {rho}S} = {partial_derivative} ln {rho}/{partial_derivative} ln V{sub S}) in response to thermal and chemical variations were investigated for the pyrolitic lower mantle. For heterogeneities with thermal origins, R{sub SP} increases from 1.7 to 2.0 together with R{sub {rho}S} decreasing from 0.4 to 0.2 and R{sub CS} = 0.27 from the top to the bottom of the lower mantle. In comparison, chemical variations (bulk iron or silica contents) are characterized by R{sub SP} < 1.5 and R{sub CS} > 0.5 at lower mantle depths. Negative values of R{sub {rho}S} and R{sub CS} are indicative of chemical anomalies in the lower mantle, but a combination of thermal and chemical heterogeneities may be required to produce velocity and density anomalies at the magnitudes observed in seismic data. Further refinement of these characteristics requires data on the higher order pressure and temperature derivatives of the elastic moduli of the constituent phases.

  19. Effect of rapid product desiccation or hydration on thermal resistance of Salmonella enterica serovar enteritidis PT 30 in wheat flour.

    PubMed

    Smith, Danielle F; Marks, Bradley P

    2015-02-01

    Salmonella is able to survive in low-moisture environments and is known to be more heat resistant as product water activity (aw) decreases. However, it is unknown how rapidly the resistance changes if product aw is altered rapidly, as can occur in certain processes. Therefore, the objective was to determine the effect of rapid product desiccation or hydration on Salmonella thermal resistance. Two dynamic moisture treatments were compared with two static moisture treatments to determine the effect of time-at-moisture on the thermal resistance of Salmonella enterica serovar Enteritidis phage type 30 (PT 30) in wheat flour. After inoculation, two static moisture groups were equilibrated to 0.3 and 0.6 aw over 4 to 7 days, and two dynamic moisture groups then were rapidly (<4 min) desiccated from 0.6 to 0.3 aw or hydrated from 0.3 to 0.6 aw. Samples then were subjected to isothermal (80°C) heat treatments, and Salmonella thermal resistance was compared via decimal reduction times (i.e., D80°C-values). The D80°C-value in flour that was rapidly desiccated from 0.6 to 0.3 aw was statistically equivalent (P > 0.05) to the D80°C-value in flour previously equilibrated to 0.3 aw, but both were greater (P < 0.05) than the D80°C-value in flour previously equilibrated to 0.6 aw. Similarly, the D80°C-value in flour rapidly hydrated from 0.3 to 0.6 aw was statistically equivalent (P > 0.05) to the D80°C-value in flour previously equilibrated to 0.6 aw, and both were less than the D80°C-value in flour previously equilibrated to 0.3 aw. Therefore, Salmonella in the rapidly desiccated flour (0.3 aw) was as thermally resistant as that which previously had been equilibrated to 0.3 aw, and Salmonella in the rapidly hydrated flour (0.6 aw) responded similarly to that in the flour previously equilibrated to 0.6 aw. These results suggest that the response period to new aw is negligible, which is critically important in applying thermal resistance data or parameters to industrial

  20. A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

    NASA Astrophysics Data System (ADS)

    Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

    2016-11-01

    We present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography-mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level resolution on

  1. A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

    SciTech Connect

    Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; Docherty, Kenneth S.; Jimenez, Jose L.

    2016-11-25

    Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arranged into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level

  2. A technique for rapid source apportionment applied to ambient organic aerosol measurements from a thermal desorption aerosol gas chromatograph (TAG)

    DOE PAGES

    Zhang, Yaping; Williams, Brent J.; Goldstein, Allen H.; ...

    2016-11-25

    Here, we present a rapid method for apportioning the sources of atmospheric organic aerosol composition measured by gas chromatography–mass spectrometry methods. Here, we specifically apply this new analysis method to data acquired on a thermal desorption aerosol gas chromatograph (TAG) system. Gas chromatograms are divided by retention time into evenly spaced bins, within which the mass spectra are summed. A previous chromatogram binning method was introduced for the purpose of chromatogram structure deconvolution (e.g., major compound classes) (Zhang et al., 2014). Here we extend the method development for the specific purpose of determining aerosol samples' sources. Chromatogram bins are arrangedmore » into an input data matrix for positive matrix factorization (PMF), where the sample number is the row dimension and the mass-spectra-resolved eluting time intervals (bins) are the column dimension. Then two-dimensional PMF can effectively do three-dimensional factorization on the three-dimensional TAG mass spectra data. The retention time shift of the chromatogram is corrected by applying the median values of the different peaks' shifts. Bin width affects chemical resolution but does not affect PMF retrieval of the sources' time variations for low-factor solutions. A bin width smaller than the maximum retention shift among all samples requires retention time shift correction. A six-factor PMF comparison among aerosol mass spectrometry (AMS), TAG binning, and conventional TAG compound integration methods shows that the TAG binning method performs similarly to the integration method. However, the new binning method incorporates the entirety of the data set and requires significantly less pre-processing of the data than conventional single compound identification and integration. In addition, while a fraction of the most oxygenated aerosol does not elute through an underivatized TAG analysis, the TAG binning method does have the ability to achieve molecular level

  3. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    NASA Astrophysics Data System (ADS)

    Alam, M. T.; Bresnehan, M. S.; Robinson, J. A.; Haque, M. A.

    2014-01-01

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m-1 K-1, is lower than the bulk basal plane value (390 W m-1 K-1) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

  4. Soil Physical, Chemical, and Thermal Characterization, Teller Road Site, Seward Peninsula, Alaska, 2016

    DOE Data Explorer

    Graham, David; Kholodov, Alexander; Busey, Bob; Romanovsky, Vladimir; Wilson, Cathy; Moon, Ji-Won

    2017-02-08

    This dataset provides the results of physical, chemical, and thermal characterization of soils at the Teller Road Site, Seward Peninsula, Alaska. Soil pits were dug from 7-14 September 2016 at designated Intensive Stations 2 through 9 at the Teller Road MM 27 Site. This dataset includes field observations and descriptions of soil layers or horizons, field measurements of soil volumetric water content, soil temperature, thermal conductivity, and heat capacity. Laboratory measurements of soil properties include gravimetric water content, bulk density, volumetric water content, and total carbon and nitrogen.

  5. Preparation and thermal conductivity of CuO nanofluid via a wet chemical method

    NASA Astrophysics Data System (ADS)

    Zhu, Haitao; Han, Dongxiao; Meng, Zhaoguo; Wu, Daxiong; Zhang, Canying

    2011-12-01

    In this article, a wet chemical method was developed to prepare stable CuO nanofluids. The influences of synthesis parameters, such as kinds and amounts of copper salts, reaction time, were studied. The thermal conductivities of CuO nanofluids were also investigated. The results showed that different copper salts resulted in different particle morphology. The concentration of copper acetate and reaction time affected the size and shape of clusters of primary nanoparticles. Nanofluids with different microstructures could be obtained by changing the synthesis parameters. The thermal conductivities of CuO nanofluids increased with the increase of particle loading.

  6. Preparation and thermal conductivity of CuO nanofluid via a wet chemical method.

    PubMed

    Zhu, Haitao; Han, Dongxiao; Meng, Zhaoguo; Wu, Daxiong; Zhang, Canying

    2011-02-28

    In this article, a wet chemical method was developed to prepare stable CuO nanofluids. The influences of synthesis parameters, such as kinds and amounts of copper salts, reaction time, were studied. The thermal conductivities of CuO nanofluids were also investigated. The results showed that different copper salts resulted in different particle morphology. The concentration of copper acetate and reaction time affected the size and shape of clusters of primary nanoparticles. Nanofluids with different microstructures could be obtained by changing the synthesis parameters. The thermal conductivities of CuO nanofluids increased with the increase of particle loading.

  7. Improvement of band gap profile in Cu(InGa)Se{sub 2} solar cells through rapid thermal annealing

    SciTech Connect

    Chen, D.S.; Yang, J.; Yang, Z.B.; Xu, F.; Du, H.W.; Ma, Z.Q.

    2014-06-01

    Highlights: • Proper RTA treatment can effectively optimize band gap profile to more expected level. • Inter-diffusion of atoms account for the improvement of the graded band gap profile. • The variation of the band gap profile created an absolute gain in the efficiency by 1.22%. - Abstract: In the paper, the effect of rapid thermal annealing on non-optimal double-graded band gap profiles was investigated by using X-ray photoelectron spectroscopy and capacitance–voltage measurement techniques. Experimental results revealed that proper rapid thermal annealing treatment can effectively improve band gap profile to more optimal level. The annealing treatment could not only reduce the values of front band gap and minimum band gap, but also shift the position of the minimum band gap toward front electrode and enter into space charge region. In addition, the thickness of Cu(InGa)Se{sub 2} thin film decreased by 25 nm after rapid thermal annealing treatment. All of these modifications were attributed to the inter-diffusion of atoms during thermal treatment process. Simultaneously, the variation of the band gap profile created an absolute gain in the efficiency by 1.22%, short-circuit current density by 2.16 mA/cm{sup 2} and filled factor by 3.57%.

  8. Hydrological and associated biogeochemical consequences of rapid global warming during the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Carmichael, Matthew J.; Inglis, Gordon N.; Badger, Marcus P. S.; Naafs, B. David A.; Behrooz, Leila; Remmelzwaal, Serginio; Monteiro, Fanny M.; Rohrssen, Megan; Farnsworth, Alexander; Buss, Heather L.; Dickson, Alexander J.; Valdes, Paul J.; Lunt, Daniel J.; Pancost, Richard D.

    2017-10-01

    The Paleocene-Eocene Thermal Maximum (PETM) hyperthermal, 56 million years ago (Ma), is the most dramatic example of abrupt Cenozoic global warming. During the PETM surface temperatures increased between 5 and 9 °C and the onset likely took < 20 kyr. The PETM provides a case study of the impacts of rapid global warming on the Earth system, including both hydrological and associated biogeochemical feedbacks, and proxy data from the PETM can provide constraints on changes in warm climate hydrology simulated by general circulation models (GCMs). In this paper, we provide a critical review of biological and geochemical signatures interpreted as direct or indirect indicators of hydrological change at the PETM, explore the importance of adopting multi-proxy approaches, and present a preliminary model-data comparison. Hydrological records complement those of temperature and indicate that the climatic response at the PETM was complex, with significant regional and temporal variability. This is further illustrated by the biogeochemical consequences of inferred changes in hydrology and, in fact, changes in precipitation and the biogeochemical consequences are often conflated in geochemical signatures. There is also strong evidence in many regions for changes in the episodic and/or intra-annual distribution of precipitation that has not widely been considered when comparing proxy data to GCM output. Crucially, GCM simulations indicate that the response of the hydrological cycle to the PETM was heterogeneous - some regions are associated with increased precipitation - evaporation (P - E), whilst others are characterised by a decrease. Interestingly, the majority of proxy data come from the regions where GCMs predict an increase in PETM precipitation. We propose that comparison of hydrological proxies to GCM output can be an important test of model skill, but this will be enhanced by further data from regions of model-simulated aridity and simulation of extreme precipitation

  9. Crystallization of sputtered lead zirconate titanate films by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Vasant Kumar, C. V. R.; Pascual, R.; Sayer, M.

    1992-01-01

    A rapid thermal annealing (RTA) technique has been employed to process lead zirconate titanate (PZT) films prepared by reactive magnetron sputtering. The films were fabricated by dc sputtering a multielement metal target in an oxygen ambient at a substrate temperature of 200 °C. A subsequent postdeposition RTA at 600 °C for 5 s crystallizes the films into a perovskite-type structure through various intermediate phases. Due to the short postdeposition processing times inherent in the RTA method, the initial nature of the as-grown films has a critical influence on the crystallization kinetics. The reaction sequence in the formation of perovskite PZT from the films deposited at low substrate temperatures by the sputtering technique has been evaluated, and various key factors influencing the crystallization of PZT have been identified. As-grown films are constituted of polycrystalline orthorhombic lead oxide in an amorphous matrix of titania and zirconia. During annealing lead oxide transforms into a cubic phase, and the lead oxide stoichiometry determines the processing route to PZT. In the case of lead-rich films, intermediate compounds of lead with titania and zirconia are observed, which react during the final stage of annealing at 600 °C to form PZT. In lead-deficient films, the formation of a pyrochlore phase has been observed, which crystallizes into perovskite at 750 °C. The Zr/Ti ratio also influences the crystallization sequence. In the case of Ti-rich PZT, the intermediate compounds initially involve a zirconium-rich rhombohedral PZT, with which residual titanium reacts to form tetragonal PZT. The films showed good ferroelectric and other electrical properties with a remanent polarization of 24 μC/cm2, coercive field of 32 kV/cm, ɛ'=950, tan δ=0.02, and σdc (300 K)=10-12 Ω-1 cm-1 with an activation energy between 0.9 and 1.4 eV.

  10. Direct synthesis and characterization of optically transparent conformal zinc oxide nanocrystalline thin films by rapid thermal plasma CVD.

    PubMed

    Pedersen, Joachim D; Esposito, Heather J; Teh, Kwok Siong

    2011-10-31

    We report a rapid, self-catalyzed, solid precursor-based thermal plasma chemical vapor deposition process for depositing a conformal, nonporous, and optically transparent nanocrystalline ZnO thin film at 130 Torr (0.17 atm). Pure solid zinc is inductively heated and melted, followed by ionization by thermal induction argon/oxygen plasma to produce conformal, nonporous nanocrystalline ZnO films at a growth rate of up to 50 nm/min on amorphous and crystalline substrates including Si (100), fused quartz, glass, muscovite, c- and a-plane sapphire (Al2O3), gold, titanium, and polyimide. X-ray diffraction indicates the grains of as-deposited ZnO to be highly textured, with the fastest growth occurring along the c-axis. The individual grains are observed to be faceted by (103) planes which are the slowest growth planes. ZnO nanocrystalline films of nominal thicknesses of 200 nm are deposited at substrate temperatures of 330°C and 160°C on metal/ceramic substrates and polymer substrates, respectively. In addition, 20-nm- and 200-nm-thick films are also deposited on quartz substrates for optical characterization. At optical spectra above 375 nm, the measured optical transmittance of a 200-nm-thick ZnO film is greater than 80%, while that of a 20-nm-thick film is close to 100%. For a 200-nm-thick ZnO film with an average grain size of 100 nm, a four-point probe measurement shows electrical conductivity of up to 910 S/m. Annealing of 200-nm-thick ZnO films in 300 sccm pure argon at temperatures ranging from 750°C to 950°C (at homologous temperatures between 0.46 and 0.54) alters the textures and morphologies of the thin film. Based on scanning electron microscope images, higher annealing temperatures appear to restructure the ZnO nanocrystalline films to form nanorods of ZnO due to a combination of grain boundary diffusion and bulk diffusion.PACS: films and coatings, 81.15.-z; nanocrystalline materials, 81.07.Bc; II-VI semiconductors, 81.05.Dz.

  11. Direct synthesis and characterization of optically transparent conformal zinc oxide nanocrystalline thin films by rapid thermal plasma CVD

    PubMed Central

    2011-01-01

    We report a rapid, self-catalyzed, solid precursor-based thermal plasma chemical vapor deposition process for depositing a conformal, nonporous, and optically transparent nanocrystalline ZnO thin film at 130 Torr (0.17 atm). Pure solid zinc is inductively heated and melted, followed by ionization by thermal induction argon/oxygen plasma to produce conformal, nonporous nanocrystalline ZnO films at a growth rate of up to 50 nm/min on amorphous and crystalline substrates including Si (100), fused quartz, glass, muscovite, c- and a-plane sapphire (Al2O3), gold, titanium, and polyimide. X-ray diffraction indicates the grains of as-deposited ZnO to be highly textured, with the fastest growth occurring along the c-axis. The individual grains are observed to be faceted by (103) planes which are the slowest growth planes. ZnO nanocrystalline films of nominal thicknesses of 200 nm are deposited at substrate temperatures of 330°C and 160°C on metal/ceramic substrates and polymer substrates, respectively. In addition, 20-nm- and 200-nm-thick films are also deposited on quartz substrates for optical characterization. At optical spectra above 375 nm, the measured optical transmittance of a 200-nm-thick ZnO film is greater than 80%, while that of a 20-nm-thick film is close to 100%. For a 200-nm-thick ZnO film with an average grain size of 100 nm, a four-point probe measurement shows electrical conductivity of up to 910 S/m. Annealing of 200-nm-thick ZnO films in 300 sccm pure argon at temperatures ranging from 750°C to 950°C (at homologous temperatures between 0.46 and 0.54) alters the textures and morphologies of the thin film. Based on scanning electron microscope images, higher annealing temperatures appear to restructure the ZnO nanocrystalline films to form nanorods of ZnO due to a combination of grain boundary diffusion and bulk diffusion. PACS: films and coatings, 81.15.-z; nanocrystalline materials, 81.07.Bc; II-VI semiconductors, 81.05.Dz. PMID:22040295

  12. Thermal conversion of biomass to valuable fuels, chemical feedstocks and chemicals

    DOEpatents

    Peters, William A [Lexington, MA; Howard, Jack B [Winchester, MA; Modestino, Anthony J [Hanson, MA; Vogel, Fredreric [Villigen PSI, CH; Steffin, Carsten R [Herne, DE

    2009-02-24

    A continuous process for the conversion of biomass to form a chemical feedstock is described. The biomass and an exogenous metal oxide, preferably calcium oxide, or metal oxide precursor are continuously fed into a reaction chamber that is operated at a temperature of at least 1400.degree. C. to form reaction products including metal carbide. The metal oxide or metal oxide precursor is capable of forming a hydrolizable metal carbide. The reaction products are quenched to a temperature of 800.degree. C. or less. The resulting metal carbide is separated from the reaction products or, alternatively, when quenched with water, hydolyzed to provide a recoverable hydrocarbon gas feedstock.

  13. Thermal dewetting with a chemically heterogeneous nano-template for self-assembled L10 FePt nanoparticle arrays

    NASA Astrophysics Data System (ADS)

    Wang, Liang-Wei; Cheng, Chung-Fu; Liao, Jung-Wei; Wang, Chiu-Yen; Wang, Ding-Shuo; Huang, Kuo-Feng; Lin, Tzu-Ying; Ho, Rong-Ming; Chen, Lih-Juann; Lai, Chih-Huang

    2016-02-01

    A design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO2 substrate, followed by a thermal annealing and reactive ion etching (RIE) process. This gives a template composed of an ordered hexagonal array of SiOC hemispheres emerging in the polystyrene matrix. After the deposition of a FePt film on this template, we utilize the rapid thermal annealing (RTA) process, which provides in-plane stress, to achieve thermal dewetting and structural ordering of FePt simultaneously. Since the template is composed of different composition surfaces with periodically varied morphologies, it offers more tuning knobs to manipulate the nanostructures. We show that both the decrease in the area of the PS matrix and the increase in the strain energy relaxation transfer the dewetted pattern from the randomly distributed nanoparticles into a hexagonal periodic array of L10 FePt nanoparticles. Transmission electron microscopy with the in situ heating stage reveals the evolution of the dewetting process, and confirms that the positions of nanoparticles are aligned with those of the SiOC hemispheres. The nanoparticles formed by this template-dewetting show an average diameter and center-to-center distance of 19.30 +/- 2.09 nm and 39.85 +/- 4.80 nm, respectively. The hexagonal array of FePt nanoparticles reveals a large coercivity of 1.5 T, much larger than the nanoparticles fabricated by top-down approaches. This approach offers an efficient pathway toward self-assembled nanostructures in a wide range of material systems.A design for the fabrication of metallic nanoparticles is presented by thermal dewetting with a chemically heterogeneous nano-template. For the template, we fabricate a nanostructured polystyrene-b-polydimethylsiloxane (PS-b-PDMS) film on a Si|SiO2 substrate, followed by a thermal

  14. Effects of rapid thermal annealing on the optical properties of strain-free quantum ring solar cells.

    PubMed

    Wu, Jiang; Wang, Zhiming M; Dorogan, Vitaliy G; Li, Shibin; Lee, Jihoon; Mazur, Yuriy I; Kim, Eun Soo; Salamo, Gregory J

    2013-01-02

    Strain-free GaAs/Al0.33Ga0.67As quantum rings are fabricated by droplet epitaxy. Both photoresponse and photoluminescence spectra confirm optical transitions in quantum rings, suggesting that droplet epitaxial nanomaterials are applicable to intermediate band solar cells. The effects of post-growth annealing on the quantum ring solar cells are investigated, and the optical properties of the solar cells with and without thermal treatment are characterized by photoluminescence technique. Rapid thermal annealing treatment has resulted in the significant improvement of material quality, which can be served as a standard process for quantum structure solar cells grown by droplet epitaxy.

  15. Effect of rapid thermal annealing on InP1-xBix grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wu, X. Y.; Wang, K.; Pan, W. W.; Wang, P.; Li, Y. Y.; Song, Y. X.; Gu, Y.; Yue, L.; Xu, H.; Zhang, Z. P.; Cui, J.; Gong, Q.; Wang, S. M.

    2015-09-01

    The effect of post-growth rapid thermal annealing on structural and optical properties of InP1-xBix thin films was investigated. InPBi shows good thermal stability up to 500 °C and a modest improvement in photoluminescence (PL) intensity with an unchanged PL spectral feature. Bismuth outdiffusion from InPBi and strain relaxation are observed at about 600 °C. The InPBi sample annealed at 800 °C shows an unexpected PL spectrum with different energy transitions.

  16. Chemical and optical properties of thermally evaporated manganese oxide thin films

    SciTech Connect

    Al-Kuhaili, M. F.

    2006-09-15

    Manganese oxide thin films were deposited using thermal evaporation from a tungsten boat. Films were deposited under an oxygen atmosphere, and the effects of thickness, substrate temperature, and deposition rate on their properties were investigated. The chemical properties of the films were studied using x-ray photoelectron spectroscopy and x-ray fluorescence. The optical properties were determined from normal-incidence transmittance and reflectance. Based on the chemical and optical characterizations, the optimum conditions for the deposition of the films were investigated. Subsequently, the optical properties (refractive index, extinction coefficient, and band gap) of these films were determined.

  17. Non-chemically Pure Magnetites Produced from Thermal Decomposition of Ankerites

    NASA Astrophysics Data System (ADS)

    Jiménez López, C.; Romanek, C.; Rodríguez-Navarro, A.; Pérez-González, T.; Rodríguez Navarro, C.

    2008-12-01

    It has been claimed that chemically pure magnetites (Fe3O4) can be obtained from thermal decomposition of (Fe, Mg, Ca)CO3 (Golden et al., 2004). Such an observation is critical, since it opens the possibility of an inorganic way of formation of the magnetites found on Martian meteorite ALH84001. Such a chemical purity is one of the parameters used, so far, to recognize bacterial origin of natural magnetites (Thomas-Keptra et al., 2001), since it has been demonstrated that biologically-controlled magnetites are chemically pure (Bazylinski and Frankel, 2004) . However, while Golden et al. (2004) obtained pure magnetite from an almost pure precursor, the ankerite cores in ALH84001 in which magnetites are embedded are far from being chemically pure, since they contain considerable amounts of Ca and Mg (Kopp and Humayun, 2003). In this study we have performed several experiments to analyze the chemical purity of magnetites produced by thermal decomposition of four ankerite samples sinthetized in the laboratory, and containing different amounts of Ca, Fe and Mg. Such a thermal decomposition was achieved by two procedures: (1) by heating the samples at 470°C under CO2 pressure and (2) by decomposing the ankerite "in situ" under the TEM (Transmission electron Microscopy) electron beam. Magnetite produced by the first procedure was analyzed by XRD to determine whether or not the resulting solid was a mixture of oxides or rather a solid solution of (Ca, Fe and Mg)oxide. Magnetites formed by the two methods were studied by High Resolution TEM. The chemical composition of about 20 crystals of each experiment was analyzed by EDAX. Under our experimental conditions, ankerites decomposed in magnetite crystals of about 5 nanometers in size. Magentite crystals arranged to keep the morphology of the precursor. Our results confirm that any of these magnetites is chemically pure, but rather, each one of them is a solid solution of Ca and Mg. Therefore, chemically pure magnetites

  18. A review of thermal-chemical conversion of lignocellulosic biomass in China.

    PubMed

    Ma, Longlong; Wang, Tiejun; Liu, Qiying; Zhang, Xinghua; Ma, Wenchao; Zhang, Qi

    2012-01-01

    Biomass, a renewable, sustainable and carbon dioxide neutral resource, has received widespread attention in the energy market as an alternative to fossil fuels. Thermal-chemical conversion of biomass to produce biofuels is a promising technology with many commercial applications. This paper reviewed the state-of-the-art research and development of thermal-chemical conversion of biomass in China with a special focus on gasification, pyrolysis, and catalytic transformation technologies. The advantages and disadvantages, potential of future applications, and challenges related to these technologies are discussed. Conclusively, these transformation technologies for the second-generation biofuels with using non-edible lignocellulosic biomass as feedstocks show prosperous perspective for commercial applications in near future. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Diffusion, Thermal Properties and Chemical Compatibilities of Select MAX Phases with Materials For Advanced Nuclear Systems

    SciTech Connect

    Barsoum, Michel; Bentzel, Grady; Tallman, Darin J.; Sindelar, Robert; Garcia-Diaz, Brenda; Hoffman, Elizabeth

    2016-04-04

    The demands of Gen IV nuclear power plants for long service life under neutron irradiation at high temperature are severe. Advanced materials that would withstand high temperatures (up to 1000+ ºC) to high doses in a neutron field would be ideal for reactor internal structures and would add to the long service life and reliability of the reactors. The objective of this work is to investigate the chemical compatibility of select MAX with potential materials that are important for nuclear energy, as well as to measure the thermal transport properties as a function of neutron irradiation. The chemical counterparts chosen for this work are: pyrolytic carbon, SiC, U, Pd, FLiBe, Pb-Bi and Na, the latter 3 in the molten state. The thermal conductivities and heat capacities of non-irradiated MAX phases will be measured.

  20. NSR&D FY15 Final Report. Modeling Mechanical, Thermal, and Chemical Effects of Impact

    SciTech Connect

    Long, Christopher Curtis; Ma, Xia; Zhang, Duan Zhong

    2015-11-02

    The main goal of this project is to develop a computer model that explains and predicts coupled mechanical, thermal and chemical responses of HE under impact and friction insults. The modeling effort is based on the LANL-developed CartaBlanca code, which is implemented with the dual domain material point (DDMP) method to calculate complex and coupled thermal, chemical and mechanical effects among fluids, solids and the transitions between the states. In FY 15, we have implemented the TEPLA material model for metal and performed preliminary can penetration simulation and begun to link with experiment. Currently, we are working on implementing a shock to detonation transition (SDT) model (SURF) and JWL equation of state.

  1. Application of a reversible chemical reaction system to solar thermal power plants

    NASA Technical Reports Server (NTRS)

    Hanseth, E. J.; Won, Y. S.; Seibowitz, L. P.

    1980-01-01

    Three distributed dish solar thermal power systems using various applications of SO2/SO3 chemical energy storage and transport technology were comparatively assessed. Each system features various roles for the chemical system: (1) energy storage only, (2) energy transport, or (3) energy transport and storage. These three systems were also compared with the dish-Stirling, using electrical transport and battery storage, and the central receiver Rankine system, with thermal storage, to determine the relative merit of plants employing a thermochemical system. As an assessment criterion, the busbar energy costs were compared. Separate but comparable solar energy cost computer codes were used for distributed receiver and central receiver systems. Calculations were performed for capacity factors ranging from 0.4 to 0.8. The results indicate that SO2/SO3 technology has the potential to be more cost effective in transporting the collected energy than in storing the energy for the storage capacity range studied (2-15 hours)

  2. Detailed Chemical Kinetic Reaction Mechanisms for Autoignition of Isomers of Heptane Under Rapid Compression

    SciTech Connect

    Westbrook, C K; Pitz, W J; Boercker, J E; Curran, H J; Griffiths, J F; Mohamed, C; Ribaucour, M

    2001-12-17

    Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new reaction sequences involving additional internal H atom abstractions not previously allowed. This process accelerates autoignition in fuels with tertiary C-H bonds in the parent fuel. In addition, the rates of hydroperoxyalkylperoxy radical isomerization reactions have all been reduced so that they are now equal to rates of analogous alkylperoxy radical isomerizations, significantly improving agreement between computed and experimental ignition delay times in the rapid compression machine. Computed ignition delay times agree well with experimental results in the few cases where experiments have been carried out for specific heptane isomers, and predictive model calculations are reported for the remaining isomers. The computed results fall into three general groups; the first consists of the most reactive isomers, including n-heptane, 2-methyl hexane and 3-methyl hexane. The second group consists of the least reactive isomers, including 2,2-dimethyl pentane, 3,3-dimethyl pentane, 2,3-dimethyl pentane, 2,4-dimethyl pentane and 2,2,3-trimethyl butane. The remaining isomer, 3-ethyl pentane, was observed computationally to have an intermediate level of reactivity. These observations are generally

  3. Degradation Of Environmental Barrier Coatings (EBC) Due To Chemical and Thermal Expansion Incompatibility

    NASA Technical Reports Server (NTRS)

    Lee, Kang N.; King, Deboran (Technical Monitor)

    2001-01-01

    Current environmental barrier coatings (EBCs) consist of multiple layers, with each layer having unique properties to meet the various requirements for successful EBCs. As a result, chemical and thermal expansion compatibility between layers becomes an important issue to maintaining durability. Key constituents in current EBCs are mullite (3Al2O3-2SiO2), BSAS (BaO(1-x)-SrO(x)-Al2O3-2SiO2), and YSZ (ZrO2-8 wt.% Y2O3). The mullite-BSAS combination appears benign although significant diffusion occurs. Mullite-YSZ and BSAS-YSZ combinations do not react up to 1500 C. Thermally grown SiO2- BSAS and mullite-BSAS-YSZ combinations are most detrimental, forming low melting glasses. Thermal expansion mismatch between YSZ and mullite or BSAS causes severe cracking and delamination.

  4. Inelastic light scattering spectroscopy in Si/SiGe nanostructures: Strain, chemical composition and thermal properties

    NASA Astrophysics Data System (ADS)

    Tsybeskov, L.; Mala, S. A.; Wang, X.; Baribeau, J.-M.; Wu, X.; Lockwood, D. J.

    2016-11-01

    We present a review of recent studies of inelastic light scattering spectroscopy in two types of Si/SiGe nanostructures: planar superlattices and cluster (dot) multilayers including first- and second-order Raman scattering, polarized Raman scattering and low-frequency inelastic light scattering associated with folded acoustic phonons. The results are used in semi-quantitative analysis of chemical composition, strain and thermal conductivity in these technologically important materials for electronic and optoelectronic devices.

  5. Distinguishing solid bitumens formed by thermochemical sulfate reduction and thermal chemical alteration

    USGS Publications Warehouse

    Kelemen, S.R.; Walters, C.C.; Kwiatek, P.J.; Afeworki, M.; Sansone, M.; Freund, H.; Pottorf, R.J.; Machel, H.G.; Zhang, T.; Ellis, G.S.; Tang, Y.; Peters, K.E.

    2008-01-01

    Insoluble solid bitumens are organic residues that can form by the thermal chemical alteration (TCA) or thermochemical sulfate reduction (TSR) of migrated petroleum. TCA may actually encompass several low temperature processes, such as biodegradation and asphaltene precipitation, followed by thermal alteration. TSR is an abiotic redox reaction where petroleum is oxidized by sulfate. It is difficult to distinguish solid bitumens associated with TCA of petroleum from those associated with TSR when both processes occur at relatively high temperature. The focus of the present work was to characterize solid bitumen samples associated with TCA or TSR using X-ray photoelectron spectroscopy (XPS). XPS is a surface analysis conducted on either isolated or in situ (>25 ??m diameter) solid bitumen that can provide the relative abundance and chemical speciation of carbon, organic and inorganic heteroatoms (NSO). In this study, naturally occurring solid bitumens from three locations, Nisku Fm. Brazeau River area (TSR-related), LaBarge Field Madison Fm. (TSR-related), and the Alaskan Brooks range (TCA-related), are compared to organic solids generated during laboratory simulation of the TSR and TCA processes. The abundance and chemical nature of organic nitrogen and sulfur in solid bitumens can be understood in terms of the nature of (1) petroleum precursor molecules, (2) the concentration of nitrogen by way of thermal stress and (3) the mode of sulfur incorporation. TCA solid bitumens originate from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. Organic sulfur in TCA organic solids remains fairly constant with increasing maturation (3.5 to ???17 sulfur per 100 carbons) into aromatic structures and to the low levels of nitrogen in their hydrocarbon precursors. Hence, XPS results provide organic chemical composition information that helps to

  6. Thermal and chemical variations of the Nigerian Benue trough lead-zinc-barite-fluorite deposits

    NASA Astrophysics Data System (ADS)

    Ogundipe, Ibukun Emmanuel

    2017-08-01

    The Benue trough is an intra-continental rift initiated in the Cretaceous during the opening of the South Atlantic Ocean. Lead-zinc-barite-fluorite mineralization occurs along the 600 km axis of the trough in three discrete sub-basins which coincide with the lower, middle and upper mineral districts of the Benue Valley. Lithologically these sub-basins are dominated by black carbonaceous shale in the Lower Benue, platform carbonates in the Middle Benue and sandstones in the Upper Benue. Micro-thermometric analysis of fluid inclusions in sphalerite, fluorite, barite and quartz have shown that each mineral district has its own unique thermal and chemical imprint. For example, the temperature can be bracketed between 109 °C and 160 °C for lower Benue, 89 °C-144 °C for the Middle Benue and 176 °C-254 °C for the Upper Benue. Chemical differentiation also exists between each mineral district with the Lower Benue having 22 wt % equivalent NaCl while the Middle and Upper Benue have 18 and 16 wt % equivalent NaCl respectively. This study shows that inter-district thermal and chemical variations exist between the ore-stage sulfide and post-sulfide gangue minerals of the entire Benue Valley. Similarly, intra-district thermal and chemical variations have also been observed among all the paragenetic minerals of each district. The thermal variations may be as a result of variations in the geothermal gradient accompanying continental rifting from one district to the other. The variations in the chemistry between the Lower Benue and the Upper Benue paragenic minerals may be as a result of the distinct lithological differences across the Benue Trough.

  7. A new technique to assess dermal absorption of volatile chemicals in vitro by thermal gravimetric analysis.

    PubMed

    Rauma, Matias; Isaksson, Tina S; Johanson, Gunnar

    2006-10-01

    Potential health hazards of dermal exposure, variability in reported dermal absorption rates and potential losses from the skin by evaporation indicate a need for a simple, inexpensive and standardized procedure to measure dermal absorption and desorption of chemical substances. The aim of this study was to explore the possibility to measure dermal absorption and desorption of volatile chemicals using a new gravimetric technique, namely thermal gravimetric analysis (TGA), and trypsinated stratum corneum from pig. Changes in skin weight were readily detected before, during and after exposure to vapours of water, 2-propanol, methanol and toluene. The shape and height of the weight curves differed between the four chemicals, reflecting differences in diffusivity and partial pressure and skin:air partitioning, respectively. As the skin weight is highly sensitive to the partial pressure of volatile chemicals, including water, this technique requires carefully controlled conditions with respect to air flow, temperature, chemical vapour generation and humidity. This new technique may help in the assessment of dermal uptake of volatile chemicals. Only a small piece of skin is needed and skin integrity is not necessary, facilitating the use of human samples. The high resolution weight-time curves obtained may also help to elucidate the characteristics of absorption, desorption and diffusion of chemicals in skin.

  8. An analytic model of axisymmetric mantle plume due to thermal and chemical diffusion

    NASA Technical Reports Server (NTRS)

    Liu, Mian; Chase, Clement G.

    1990-01-01

    An analytic model of axisymmetric mantle plumes driven by either thermal diffusion or combined diffusion of both heat and chemical species from a point source is presented. The governing equations are solved numerically in cylindrical coordinates for a Newtonian fluid with constant viscosity. Instead of starting from an assumed plume source, constraints on the source parameters, such as the depth of the source regions and the total heat input from the plume sources, are deduced using the geophysical characteristics of mantle plumes inferred from modelling of hotspot swells. The Hawaiian hotspot and the Bermuda hotspot are used as examples. Narrow mantle plumes are expected for likely mantle viscosities. The temperature anomaly and the size of thermal plumes underneath the lithosphere can be sensitive indicators of plume depth. The Hawaiian plume is likely to originate at a much greater depth than the Bermuda plume. One suggestive result puts the Hawaiian plume source at a depth near the core-mantle boundary and the source of the Bermuda plume in the upper mantle, close to the 700 km discontinuity. The total thermal energy input by the source region to the Hawaiian plume is about 5 x 10(10) watts. The corresponding diameter of the source region is about 100 to 150 km. Chemical diffusion from the same source does not affect the thermal structure of the plume.

  9. Comparison of chemical and thermal protein denaturation by combination of computational and experimental approaches. II

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Christiansen, Alexander; Samiotakis, Antonios; Wittung-Stafshede, Pernilla; Cheung, Margaret S.

    2011-11-01

    Chemical and thermal denaturation methods have been widely used to investigate folding processes of proteins in vitro. However, a molecular understanding of the relationship between these two perturbation methods is lacking. Here, we combined computational and experimental approaches to investigate denaturing effects on three structurally different proteins. We derived a linear relationship between thermal denaturation at temperature Tb and chemical denaturation at another temperature Tu using the stability change of a protein (ΔG). For this, we related the dependence of ΔG on temperature, in the Gibbs-Helmholtz equation, to that of ΔG on urea concentration in the linear extrapolation method, assuming that there is a temperature pair from the urea (Tu) and the aqueous (Tb) ensembles that produces the same protein structures. We tested this relationship on apoazurin, cytochrome c, and apoflavodoxin using coarse-grained molecular simulations. We found a linear correlation between the temperature for a particular structural ensemble in the absence of urea, Tb, and the temperature of the same structural ensemble at a specific urea concentration, Tu. The in silico results agreed with in vitro far-UV circular dichroism data on apoazurin and cytochrome c. We conclude that chemical and thermal unfolding processes correlate in terms of thermodynamics and structural ensembles at most conditions; however, deviations were found at high concentrations of denaturant.

  10. Thermal and chemical unfolding and refolding of a eukaryotic sodium channel.

    PubMed

    Charalambous, Kalypso; O'Reilly, A O; Bullough, Per A; Wallace, B A

    2009-06-01

    Voltage-gated sodium channels are dynamic membrane proteins essential for signaling in nervous and muscular systems. They undergo substantial conformational changes associated with the closed, open and inactivated states. However, little information is available regarding their conformational stability. In this study circular dichroism spectroscopy was used to investigate the changes in secondary structure accompanying chemical and thermal denaturation of detergent-solubilised sodium channels isolated from Electrophorus electricus electroplax. The proteins appear to be remarkably resistant to either type of treatment, with "denatured" channels, retaining significant helical secondary structure even at 77 degrees C or in 10% SDS. Further retention of helical secondary structure at high temperature was observed in the presence of the channel-blocking tetrodotoxin. It was possible to refold the thermally-denatured (but not chemically-denatured) channels in vitro. The correctly refolded channels were capable of undergoing the toxin-induced conformational change indicative of ligand binding. In addition, flux measurements in liposomes showed that the thermally-denatured (but not chemically-denatured) proteins were able to re-adopt native, active conformations. These studies suggest that whilst sodium channels must be sufficiently flexible to undergo major conformational changes during their functional cycle, the proteins are highly resistant to unfolding, a feature that is important for maintaining structural integrity during dynamic processes.

  11. Thermal and chemical unfolding and refolding of a eukaryotic sodium channel

    PubMed Central

    Charalambous, Kalypso; O'Reilly, A.O.; Bullough, Per A.; Wallace, B.A.

    2009-01-01

    Voltage-gated sodium channels are dynamic membrane proteins essential for signaling in nervous and muscular systems. They undergo substantial conformational changes associated with the closed, open and inactivated states. However, little information is available regarding their conformational stability. In this study circular dichroism spectroscopy was used to investigate the changes in secondary structure accompanying chemical and thermal denaturation of detergent-solubilised sodium channels isolated from Electrophorus electricus electroplax. The proteins appear to be remarkably resistant to either type of treatment, with “denatured” channels, retaining significant helical secondary structure even at 77 °C or in 10% SDS. Further retention of helical secondary structure at high temperature was observed in the presence of the channel-blocking tetrodotoxin. It was possible to refold the thermally-denatured (but not chemically-denatured) channels in vitro. The correctly refolded channels were capable of undergoing the toxin-induced conformational change indicative of ligand binding. In addition, flux measurements in liposomes showed that the thermally-denatured (but not chemically-denatured) proteins were able to re-adopt native, active conformations. These studies suggest that whilst sodium channels must be sufficiently flexible to undergo major conformational changes during their functional cycle, the proteins are highly resistant to unfolding, a feature that is important for maintaining structural integrity during dynamic processes. PMID:19232514

  12. Monovarietal extra virgin olive oils. Correlation between thermal properties and chemical composition: heating thermograms.

    PubMed

    Chiavaro, Emma; Vittadini, Elena; Rodriguez-Estrada, Maria Teresa; Cerretani, Lorenzo; Bendini, Alessandra

    2008-01-23

    Extra virgin olive oils from drupes of three Sicilian varieties (Biancolilla, Cerasuola, and Nocellara del Belice) collected at three different harvesting periods were analyzed upon heating by means of DSC, and thermal properties were related to the chemical composition of the samples. All thermograms exhibited multiple transitions with a minor exothermic peak, followed by a major endothermic event. Cerasuola samples showed higher overall enthalpy and narrower range of transition at all harvesting periods, as compared to the other oils. A more ordered crystal structure originating from a more uniform chemical composition, with higher triolein content, in Cerasuola may be hypothesized. At different harvesting periods, thermal transitions started at lower temperatures and developed over a narrower range in all cultivars, probably due to the insertion of molecules derived from triacylglycerol lysis (diacylglycerols and free fatty acids) and lipid oxidation products into the triacylglycerol crystal lattice. All heating thermograms were deconvoluted into one exothermic and five endothermic constituent peaks, and the effect of chemical components on thermal properties of the peaks was evaluated. DSC application upon heating appears to be very promising in discriminating among oil samples from olives of different cultivars and/or harvesting periods.

  13. The influence of wavelength-dependent radiation in simulation of lamp-heated rapid thermal processing systems

    SciTech Connect

    Ting, A.

    1994-08-01

    Understanding the thermal response of lamp-heated rapid thermal processing (RTP) systems requires understanding relatively complex radiation exchange among opaque and partially transmitting surfaces and materials. The objective of this paper is to investigate the influence of wavelength-dependent radiative properties. The examples used for the analysis consider axisymmetric systems of the kind that were developed by Texas Instruments (TI) for the Microelectronics Manufacturing Science and Technology (MMST) Program and illustrate a number of wavelength-dependent (spectral) effects. The models execute quickly on workstation class computing flatforms, and thus permit rapid comparison of alternative reactor designs and physical models. The fast execution may also permit the incorporation of these models into real-time model-based process control algorithms.

  14. Tunable photoluminescence of self-assembled GeSi quantum dots by B{sup +} implantation and rapid thermal annealing

    SciTech Connect

    Chen, Yulu; Wu, Shan; Ma, Yinjie; Fan, Yongliang; Yang, Xinju; Zhong, Zhenyang; Jiang, Zuimin

    2014-06-21

    The layered GeSi quantum dots (QDs) are grown on (001) Si substrate by molecular beam epitaxy. The photoluminescence (PL) peak of the as-grown GeSi quantum dots has obvious blue shift and enhancement after processed by ion implantation and rapid thermal annealing. It is indicated that the blue shift is originated from the interdiffusion of Ge and Si at the interface between QDs and the surrounding matrix. The dependence of PL intensity on the excitation power shows that there are the nonradiative centers of shallow local energy levels from the point defects caused by the ion implantation, but not removed by the rapid thermal annealing. The tunable blue shift of the PL position from the 1300 nm to 1500 nm region may have significant application value in the optical communication.

  15. Thermal transport at a solid-nanofluid interface: from increase of thermal resistance towards a shift of rapid boiling.

    PubMed

    Han, Haoxue; Merabia, Samy; Müller-Plathe, Florian

    2017-06-22

    We use molecular dynamics simulations to investigate interfacial thermal transport between an ethanol suspension containing gold atomic clusters and a gold surface, using both realistic and simplified molecular models of nanoparticles. The interfacial thermal conductance was determined via a thermal relaxation method for a variety of nanoparticle-nanoparticle and nanoparticle-surface interaction strengths. The Kapitza resistance is found to increase due to the presence of nanoparticles in the vicinity of the solid-liquid interface. The heat flow from the solid to the nanoparticles is separated from its counterpart from the solid to the liquid to discriminate their respective contribution to the total heat current. A per-vibrational-mode analysis highlights a shift of major heat carriers from low frequencies towards higher frequencies due to the coupling of the internal nanoparticle dynamics to the gold surface, in addition to stronger particle-surface interactions. Finally, we demonstrate that the increase of the Kapitza resistance significantly shifts the nanofluid/solid surface explosive boiling temperature to higher temperatures compared to pure ethanol.

  16. Extended-Boussinesq thermal-chemical convection with moving heat sources and variable viscosity

    NASA Astrophysics Data System (ADS)

    Hansen, U.; Yuen, D. A.

    2000-03-01

    We have studied with an aspect-ratio four box the thermal-chemical convective evolution with strongly temperature- and depth-dependent viscosity and moving heat sources within the extended-Boussinesq framework, in which both adiabatic and viscous heating are included and a depth-dependent thermal expansivity is assumed in the equation of state. Our focus is to show how this type of mantle evolution with an averaged Ra of 0(10 6) may develop with a linear chemical stratification and a uniformly hot mantle as an initial condition. The effects of extended-Boussinesq and depth-dependent thermal expansivity are to prevent the effective destruction of the chemical heterogeneities. Our results show that this initial condition would, after the age of the Earth, lead to a 'lava lamp' mode consisting of a thick chemically stratified and intensely internally heated layer with a thickness of around a quarter of the whole mantle thickness. However, in this isolated internally convecting layer, exceedingly high temperatures greater than 4500 K would be reached in the deep mantle. Plumes can be launched from the top of this thick denser layer. This 'lava lamp' stage would give way to the formation of denser hill-like structures at the core-mantle boundary. Then upwellings with deep lower mantle origins can be induced by the interaction of the downwellings with the D″ layer. Our simulations show the possibility for some long-range mass transfer interaction between these widely separated chemical hills promoted by the fast horizontal flow induced by the sinking currents along the low-viscosity zone due to temperature-dependent rheology at the core-mantle boundary.

  17. Processing of Mn-Al nanostructured magnets by spark plasma sintering and subsequent rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Saravanan, P.; Vinod, V. T. P.; Černík, Miroslav; Selvapriya, A.; Chakravarty, Dibyendu; Kamat, S. V.

    2015-01-01

    The potential of spark plasma sintering (SPS) in combination with rapid thermal annealing (RTA) for the processing of Mn-Al nanostructured magnets is explored in this study. Ferromagnetic α-Mn alloy powders were processed by high-energy ball milling using Mn (56 at%) and Al (44 at%) as constituent metal elements. The alloying action between Mn and Al due to intensive milling was studied by X-ray diffraction and field-emission scanning electron microscope; while the phase transformation kinetics was investigated using differential scanning calorimetry. The evolution of ferromagnetic properties in the as-milled powders was studied by superconducting quantum interference device (SQUID). Among the Mn-Al alloy powders collected at various milling intervals, the 25 h milled Mn-Al powders showed a good combination of coercivity, Hc (11.3 kA/m) and saturation magnetization, Ms (5.0 A/m2/kg); accordingly, these powders were chosen for SPS. The SPS experiments were conducted at different temperatures: 773, 873 and 973 K and its effect on the density, phase composition and magnetic properties of the Mn-Al bulk samples were investigated. Upon increasing the SPS temperature from 773 to 973 K, the bulk density was found to increase from 3.6 to 4.0 g/cm3. The occurrence of equilibrium β-phase with significant amount of γ2-phase was obvious at all the SPS temperatures; however, crystallization of some amount of τ-phase was evident at 973 K. Irrespective of the SPS temperatures, all the samples demonstrated soft magnetic behavior with Hc and Ms values similar to those obtained for the 25 h milled powders. The magnetic properties of the SPSed samples were significantly improved upon subjecting them to RTA at 1100 K. Through the RTA process, Hc values of 75, 174 and 194 kA/m and Ms values of 19, 21 and 28 A/m2/kg were achieved for the samples SPSed at 773, 873 and 973 K, respectively. The possible reasons for the observed improvement in the magnetic properties of the SPSed

  18. Carbon effect on the survival of vacancies in Czochralski silicon during rapid thermal anneal

    NASA Astrophysics Data System (ADS)

    Zhao, Jian; Dong, Peng; Yuan, Kang; Qiu, Xiaodong; Zhou, Junwei; Zhao, Jianjiang; Yu, Xuegong; Ma, Xiangyang; Yang, Deren

    2017-07-01

    Rapid thermal anneal (RTA) at high temperatures can be employed to introduce vacancies to control oxygen precipitation (OP) behavior in Czochralski (CZ) silicon. Such excessive vacancies survive from the recombination of silicon-interstitials and vacancies (V-I recombination) during the RTA. In this work, we aim to elucidate the carbon effect on the survival of vacancies in CZ silicon during the high temperature RTA by means of gold diffusion in combination with deep-level transient spectroscopy. It is revealed that the existence of ˜1017 cm-3 carbon atoms significantly increases the amount of survival vacancies in the form of vacancy-oxygen (VOm, m ≥ 2) complexes in CZ silicon when subjected to the 1250 °C/60 s RTA. Moreover, such an increase in the number of vacancies becomes more significant with the increase in the cooling rate of RTA. The density functional theory calculations suggest that the V-I recombination is to some extent unfavorable as a carbon atom is close to the silicon-interstitial. Alternatively, it is believed that the substitutional carbon (Cs) atoms tend to trap the silicon-interstitials, thus forming Ci complexes (Cs + I → Ci) in CZ silicon during the RTA. In this context, the V-I recombination is suppressed in a manner, leading to the survival of more vacancies, thus generating more VOm complexes. Furthermore, after the 1250 °C/60 s RTA, the oxide precipitate nucleation based on the VOm complexes is more significant in carbon-rich CZ (CCZ) silicon than in the conventional CZ counterpart. Hence, when subjected to the same OP anneal consisting of the nucleation anneal at 650 or 800 °C for 4 h and the subsequent growth anneal at 1000 °C for 16 h, CCZ silicon possesses a higher density of bulk microdefects and therefore stronger internal gettering capability than CZ silicon. However, the nucleation temperature for OP should be carefully selected as 650 °C for CCZ silicon in order to form an oxide precipitate-free denuded zone.

  19. Rapid localization of point mutations in PCR products by chemical (HOT) modification.

    PubMed

    Tindall, K R; Whitaker, R A

    1991-01-01

    Our studies of mutational mechanisms in mammalian cells use the AS52 Chinese hamster ovary cell line. AS52 mutants can be selected as 6-thioguanine resistant colonies and mutations are studied at a chromosomally integrated gpt locus. Mutant gpt sequences are amplified using the polymerase chain reaction (PCR) to distinguish deletions from putative point mutations. PCR is efficiently performed from a few thousand lysed cells or from isolated genomic DNA. Amplified mutant PCR fragments carrying putative point mutations are further characterized by localizing the site of the mutation using chemical modification. A heteroduplex molecule consisting of one wild-type and one mutant DNA strand is generated. A base mismatch will be produced at the site of the mutation. Mismatched cytosine or thymine residues are sensitive to modification by hydroxylamine or osmium tetroxide, respectively. The modified DNA heteroduplex is then sensitive to piperidine cleavage. If one strand is 32P-end labeled, then the cleavage product can be separated on a denaturing acrylamide sequencing gel and visualized using autoradiography. Thus, the site of a mutation can be localized to a specific region of the gene, thereby simplifying the DNA sequence analysis and facilitating the rapid generation of mutational sequence spectra.

  20. Rapid localization of point mutations in PCR products by chemical (HOT) modification

    SciTech Connect

    Tindall, K.R.; Whitaker, R.A. )

    1991-01-01

    The studies of mutational mechanisms in mammalian cells use the AS52 Chinese hamster ovary cell line. Mutant gpt sequences are amplified using the polymerase chain reaction (PCR) to distinguish deletions from putative point mutations. PCR is efficiently performed from a few thousand lysed cells or from isolated genomic DNA. Amplified mutant PCR fragments carrying putative point mutations are further characterized by localizing the site of the mutation using chemical modification. A heteroduplex molecule consisting of one wild-type and one mutant DNA strand is generated. A base mismatch will be produced at the site of the mutation. Mismatched cytosine or thymine residues are sensitive to modification by hydroxylamine or osmium tetroxide, respectively. The modified DNA heteroduplex is then sensitive to piperidine cleavage. If one strand is {sup 32}P-end labeled, then the cleavage product can be separated on a denaturing acrylamide sequencing gel and visualized using autoradiography. Thus, the site of a mutation can be localized to a specific region of the gene, thereby simplifying the DNA sequence analysis and facilitating the rapid generation of mutational sequence spectra.

  1. Simultaneous rapid chemical synthesis of over one hundred oligonucleotides on a microscale

    PubMed Central

    Matthes, Hans W.D.; Zenke, W. Martin; Grundström, Thomas; Staub, Adrien; Wintzerith, Marguerite; Chambon, Pierre

    1984-01-01

    An inexpensive, extremely rapid manual method for simultaneous synthesis of large numbers of oligodeoxyribonucleotides on 50 or 150 nanomole scale is described. The oligonucleotides are assembled in parallel by the phosphotriester method on small cellulose paper disks in a simple gas pressure-controlled continuous-flow system. For each addition of a nucleotide the disks are sorted into four sets which are placed in four columns for addition of A, C, G and T, respectively. During one 2-week period, three rounds of synthesis by this method yielded 254 oligomers (8- to 22-mers), many of which were also purified during this time. Using 50 nanomole scale reactions the yields for 17-mers, for example, were in the range of 0.5 O.D.260 units (˜5 nmol, i.e., ˜10% yield), an amount sufficient for most purposes. The equipment required is relatively inexpensive and for the most part usually already available in molecular biology laboratories. All chemicals are commercially available and the current reagent cost per oligonucleotide (25 μg, average length 17-mer) is ˜3 US dollars. ImagesFig. 1.Fig. 3.Fig. 4.Fig. 5. PMID:16453516

  2. Thermal stability of Trichoderma reesei c30 cellulase and aspergillus niger; -glucosidase after ph and chemical modification

    SciTech Connect

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  3. Thermal stability of Trichoderma reesei C30 cellulase and Aspergillus niger. beta. -glucosidase after pH and chemical modification

    SciTech Connect

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger ..beta..-glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  4. Thermal Conductivity of Nanocrystalline Silicon Prepared by Plasma-Enhanced Chemical-Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Jugdersuren, Battogtokh; Liu, Xiao; Kearney, Brian; Queen, Daniel; Metcalf, Thomas; Culbertson, James; Chervin, Christopher; Katz, Michael; Stroud, Rhonda

    Nanocrystallization by ball milling has been used successfully to reduce the thermal conductivity of silicon-germanium alloys (SiGe) and turn them into useful thermoelectric materials at a temperature of a few hundred degrees C. Currently the smallest grain sizes in nanocrystalline SiGe are in the 10 nm range. Germanium is added to scatter short wavelength phonons by impurity scattering. In this work, we report a record low thermal conductivity in nanocrystalline silicon prepared by plasma-enhanced chemical-vapor deposition. By varying hydrogen to silane ratio, we can vary the average grain sizes from greater than 10 nm down to 3 nm, as determined by both the high resolution transmission electron microscopy and X-ray diffraction. The values of thermal conductivity, as measured by the 3 ω technique, can be correspondingly modulated from that of ball-milled nanocrystalline SiGe to a record low level of 0.3 W/mK at room temperature. This low thermal conductivity is only about 1/3 of the minimum thermal conductivity limit of silicon. Possible causes of such a large reduction are discussed. Work supported by the Office of Naval Research.

  5. Thermal/chemical degradation of ceramic cross-flow filter materials

    SciTech Connect

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  6. Titanomagnetite Curie temperatures: Effects of vacancies, chemical/cation ordering and thermal history

    NASA Astrophysics Data System (ADS)

    Jackson, M. J.; Bowles, J. A.; Lappe, S. C. L. L.; Solheid, P.

    2016-12-01

    Recent experimental work [Bowles et al, 2013, Nat. Commun.; Jackson and Bowles, 2014, G-cubed] has shown that the Curie temperatures (Tc) of intermediate-composition titanomagnetites (TM30-TM50) depend strongly on thermal history, with Tc increases of ≥100°C produced by moderate-temperature (300°-400° C) annealing in the lab or in slow natural cooling. Equally large decreases are produced by rapid cooling ("quenching") from higher temperatures. The phenomenon is robustly defined and repeatable, but the underlying mechanism remains enigmatic, presumably involving rearrangement of metal cations within the spinel lattice without any change in bulk composition. Previous studies [e.g., Moskowitz and Wanamaker, 1994, GRL; Lattard et al, 2006, JGR] have shown that cation deficiency controls Tc both directly, by changing the ferrous/ferric ratio, and indirectly, by affecting the cation ordering. Our new experiments examined the effects of oxidation state and nonstoichiometry on the magnitude of Tc changes produced by quenching/annealing. In our synthetic TMs these changes are generally relatively small (ΔTc<35°), but when the samples are oxidized by heating in air (150°-250°C for 23-110 h) prior to annealing (300°-400° C for 10-1000 h in vacuum), ΔTc reaches 100°C or more, similar to the changes observed in our natural TMs. Conversely, in our natural samples annealing and quenching can cause quite large changes (ΔTc>100°), but when the samples are embedded in a reducing material (containing graphite), ΔTc becomes insignificant. These results strongly suggest that cation vacancies play an essential role in the cation rearrangements responsible for the observed changes in Tc. XMCD and low-temperature Mossbauer and magnetization measurements show no evidence of corresponding changes in ferrous/ferric site occupancy, and some form of octahedral-site chemical clustering or short-range ordering appears to be the best way to explain the large observed changes in

  7. Thermally stable harpin, HrpZPss is sensitive to chemical denaturants: probing tryptophan environment, chemical and thermal unfolding by fluorescence spectroscopy.

    PubMed

    Tarafdar, Pradip K; Vedantam, Lakshmi Vasudev; Podile, Appa Rao; Swamy, Musti J

    2013-12-01

    Harpins - a group of proteins that elicit hypersensitive response (HR) in non-host plants - are secreted by certain Gram-negative plant pathogenic bacteria upon interaction with the plant. In the present study, the microenvironment and solvent accessibility of the sole tryptophan residue (Trp-167) in harpin HrpZPss, secreted by Pseudomonas syringae pv. syringae, have been characterized by fluorescence spectroscopic studies. Emission λmax of the native protein at 328 nm indicates that Trp-167 is buried in a hydrophobic region in the interior of the protein matrix. Significant quenching (53%) was seen with the neutral quencher, acrylamide at 0.5 M concentration, whereas quenching by ionic quenchers, I(-) (~10%) and Cs(+) (negligible) was considerably lower. In the presence of 6.0 M guanidine hydrochloride (GdnHCl) the emission λmax shifted to 350.5 nm, and quenching by both neutral and ionic quenchers increased significantly, suggesting complete exposure of the indole side chain to the aqueous medium. Fluorescence studies on the thermal unfolding of HrpZPss are fully consistent with a complex thermal unfolding process and high thermal stability of this protein, inferred from previous differential scanning calorimetric and dynamic light scattering studies. However, the protein exhibits low resistance to chemical denaturants, with 50% unfolding seen in the presence of 1.77 M GdnHCl or 3.59 M urea. The ratio of m value, determined from linear extrapolation model, for GdnHCl and urea-induced unfolding was 1.8 and suggests the presence of hydrophobic interactions, which could possibly involve leucine zipper-like helical regions on the surface of the protein.

  8. Boron Nitride Nanosheets (BNNSs) Chemically Modified by "Grafting-From" Polymerization of Poly(caprolactone) for Thermally Conductive Polymer Composites.

    PubMed

    Lee, Jinseong; Jung, Haejong; Yu, Seunggun; Man Cho, Suk; Tiwari, Vimal K; Babu Velusamy, Dhinesh; Park, Cheolmin

    2016-07-05

    To meet the growing demand for rapid heat dissipation in electronic devices to ensure their reliable performance with a high level of safety, many polymer composites with thermally conductive but electrically insulating 2D boron nitride nanosheets (BNNSs) are being developed. Here we present an efficient way to enhance the thermal conductivity (TC) of a polymer composite by means of "grafting-from" polymerization of a poly(caprolactone) (PCL) onto BNNSs. The BNNSs, which were exfoliated from bulk BN by means of ultra-sonication, were prepared by means of radical oxidation. These oxidized BNNSs (oxi-BNNSs) were employed as initiators for subsequent ring-opening polymerization of PCL, which successfully resulted in PCL chemically grafted onto BNNSs (PCL-g-BNNSs). The excellent dispersion of PCL-g-BNNSs in common solvents allowed us to readily fabricate a polymer composite that contained PCL-g-BNNSs embedded in a PCL matrix, and the composite showed TC values that were five and nine times greater in the out-of-plane and in-plane mode, respectively, than those of pristine PCL.

  9. Evaluation of Applied Materials` rapid thermal processor using SEMATECH methodologies for 0.25 {micro}m technology thermal applications. Part 1

    SciTech Connect

    Riley, T.J.; Nanda, A.K.; Miner, G.; Pas, M.F.; Hossain-Pas, S.; Velo, L.A.

    1996-12-01

    Under a joint development contract with Applied Materials (AMAT) and Texas Instruments (TI), SEMATECH undertook a project (Joint Development Project J100) with a goal of delivering a cost effective, technically advanced rapid Thermal Processor (RTP). The RTP tool was specified to meet the present and future manufacturing needs of SEMATECH`s member companies. The J100 results contained here focus on the temperature and control performance of the AMAT RTP tool. The evaluation methodology included passive data collection (PDC) to check the tool stability, screening experiments to isolate the variable interaction and to define the process window, broad range and narrow range sensitivity studies to determine the sheet resistance dependence on thermal budget for small increments in temperature set point, perturbation experiments to determine localized control, and stability experiments to check for drift and process repeatability. The impact of wafer emissivity on source/drain rapid-thermal annealing was evaluated by processing wafers with varying backside films. The PDC experiments demonstrated the tool to be stable. Screening experiments revealed the strong effect of temperature, followed by time, and time-temperature interaction on sheet resistance. Boron implanted (p+/n) wafers were found to be sensitive at a temperature of 1,025 C or less for a 10 second anneal whereas arsenic implanted wafers (n+/p) showed greater sensitivity at temperatures ranging from 1,025 C to 1,100 C for a 10 second anneal.

  10. Rapid fabrication of a four-layer PMMA-based microfluidic chip using CO2-laser micromachining and thermal bonding

    NASA Astrophysics Data System (ADS)

    Chen, Xueye; Shen, Jienan; Zhou, Mengde

    2016-10-01

    A smart design method to transform the original two-layer microfluidic chip into a four-layer 3D microfluidic chip is proposed. A novel fabrication method is established to rapidly and effectively produce a four-layer microfluidic chip device made entirely from polymethylmethacrylate (PMMA). Firstly, the CO2-laser cuts the PMMA sheets by melting and blowing away vaporized material from the parent material to obtain high-quality channels of the microfluidic chip. An orthogonal experimental method is used to study its processing stability. In addition, a simple, rapid thermal bonding technique is successfully applied in fabricating the four-layer microfluidic chip, which has a bond strength of 1.3 MPa. A wooden pole is used to improve the accuracy of the alignment. Finally, a mixing experiment with blue ink and water is carried out, which proves that this smart design method and rapid manufacturing technology are successful.

  11. High Temperature Nanocomposites For Nuclear Thermal Propulsion and In-Space Fabrication by Hyperbaric Pressure Laser Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Webb, N. D.; Espinoza, M.; Cook, S.; Houts, M.; Kim, T.

    Nuclear Thermal Propulsion (NTP) is an indispensable technology for the manned exploration of the solar system. By using Hyperbaric Pressure Laser Chemical Vapor Deposition (HP-LCVD), the authors propose to design and build a promising next-generation fuel element composed of uranium carbide UC embedded in a latticed matrix of highly refractory Ta4HfC5 for an NTP rocket capable of sustaining temperatures up to 4000 K, enabling an Isp of up to 1250 s. Furthermore, HP-LCVD technology can also be harnessed to enable 3D rapid prototyping of a variety of materials including metals, ceramics and composites, opening up the possibility of in-space fabrication of components, replacement parts, difficult-to-launch solar sails and panels and a variety of other space structures. Additionally, rapid prototyping with HP-LCVD makes a feasible "live off the land" strategy of interplanetary and interstellar exploration ­ the precursors commonly used in the technology are found, often in abundance, on other solar system bodies either as readily harvestable gas (e.g. methane) or as a raw material that could be converted into a suitable precursor (e.g. iron oxide into ferrocene on Mars).

  12. Nanophotonic Atomic Force Microscope Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale [Nanophotonic AFM Transducers Enable Chemical Composition and Thermal Conductivity Measurements at the Nanoscale

    DOE PAGES

    Chae, Jungseok; An, Sangmin; Ramer, Georg; ...

    2017-08-03

    The atomic force microscope (AFM) offers a rich observation window on the nanoscale, yet many dynamic phenomena are too fast and too weak for direct AFM detection. Integrated cavity-optomechanics is revolutionizing micromechanical sensing; however, it has not yet impacted AFM. Here, we make a groundbreaking advance by fabricating picogram-scale probes integrated with photonic resonators to realize functional AFM detection that achieve high temporal resolution (<10 ns) and picometer vertical displacement uncertainty simultaneously. The ability to capture fast events with high precision is leveraged to measure the thermal conductivity (η), for the first time, concurrently with chemical composition at the nanoscalemore » in photothermal induced resonance experiments. The intrinsic η of metal–organic-framework individual microcrystals, not measurable by macroscale techniques, is obtained with a small measurement uncertainty (8%). The improved sensitivity (50×) increases the measurement throughput 2500-fold and enables chemical composition measurement of molecular monolayer-thin samples. In conclusion, our paradigm-shifting photonic readout for small probes breaks the common trade-off between AFM measurement precision and ability to capture transient events, thus transforming the ability to observe nanoscale dynamics in materials.« less

  13. Unravelling the fundamentals of thermal and chemical expansion of BaCeO3 from first principles phonon calculations.

    PubMed

    Løken, Andreas; Haugsrud, Reidar; Bjørheim, Tor S

    2016-11-16

    Differentiating chemical and thermal expansion is virtually impossible to achieve experimentally. While thermal expansion stems from a softening of the phonon spectra, chemical expansion depends on the chemical composition of the material. In the present contribution, we, for the first time, completely decouple thermal and chemical expansion through first principles phonon calculations on BaCeO3, providing new fundamental insights to lattice expansion. We assess the influence of defects on thermal expansion, and how this in turn affects the interpretation of chemical expansion and defect thermodynamics. The calculations reveal that the linear thermal expansion coefficient is lowered by the introduction of oxygen vacancies being 10.6 × 10(-6) K(-1) at 300 K relative to 12.2 × 10(-6) K(-1) for both the protonated and defect-free bulk lattice. We further demonstrate that the chemical expansion coefficient upon hydration varies with temperature, ranging from 0.070 to 0.115 per mole oxygen vacancy. Ultimately, we find that, due to differences in the thermal expansion coefficients under dry and wet conditions, the chemical expansion coefficients determined experimentally are grossly underestimated - around 55% lower in the case of 10 mol% acceptor doped BaCeO3. Lastly, we evaluate the effect of these volume changes on the vibrational thermodynamics.

  14. How Irreversible Heat Transport Processes Drive Earth's Interdependent Thermal, Structural, and Chemical Evolution Providing a Strongly Heterogeneous, Layered Mantle

    NASA Astrophysics Data System (ADS)

    Hofmeister, A.; Criss, R. E.

    2013-12-01

    Because magmatism conveys radioactive isotopes plus latent heat rapidly upwards while advecting heat, this process links and controls the thermal and chemical evolution of Earth. We present evidence that the lower mantle-upper mantle boundary is a profound chemical discontinuity, leading to observed heterogeneities in the outermost layers that can be directly sampled, and construct an alternative view of Earth's internal workings. Earth's beginning involved cooling via explosive outgassing of substantial ice (mainly CO) buried with dust during accretion. High carbon content is expected from Solar abundances and ice in comets. Reaction of CO with metal provided a carbide-rich core while converting MgSiO3 to olivine via oxidizing reactions. Because thermodynamic law (and buoyancy of hot particles) indicates that primordial heat from gravitational segregation is neither large nor carried downwards, whereas differentiation forced radioactive elements upwards, formation of the core and lower mantle greatly cooled the Earth. Reference conductive geotherms, calculated using accurate and new thermal diffusivity data, require that heat-producing elements are sequestered above 670 km which limits convection to the upper mantle. These irreversible beginnings limit secular cooling to radioactive wind-down, permiting deduction of Earth's inventory of heat-producing elements from today's heat flux. Coupling our estimate for heat producing elements with meteoritic data indicates that Earth's oxide content has been underestimated. Density sorting segregated a Si-rich, peridotitic upper mantle from a refractory, oxide lower mantle with high Ca, Al and Ti contents, consistent with diamond inclusion mineralogy. Early and rapid differentiation means that internal temperatures have long been buffered by freezing of the inner core, allowing survival of crust as old as ca.4 Ga. Magmatism remains important. Melt escaping though stress-induced fractures in the rigid lithosphere imparts a

  15. Characterization and photo-chemical applications of nano-ZnO prepared by wet chemical and thermal decomposition methods

    SciTech Connect

    Mousa, M.A.; Bayoumy, W.A.A.; Khairy, M.

    2013-11-15

    Graphical abstract: - Highlights: • Nano-ZnO particles were synthesized by soft-wet precipitation and dry methods. • ZnO nanoparticle with different morphologies was obtained. • Nano ZnO samples showed a high photocatalytic activity. • ZnO nanoparticle showed strong ultraviolet emission at room temperature. • The samples showed high biological activity depending on their synthetic method. - Abstract: Nano-crystalline ZnO particles were synthesized using two different routes: soft-wet and dry methods. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to identify the particles structures and morphologies, while X-ray diffraction (XRD) was used for verifying the particles crystal structure. The thermal stabilities of the particles were examined through thermal gravimetric analysis technique and their surface areas were calculated using BET method. Moreover, the photocatalytic activities were evaluated using UV–vis spectroscopy and photoluminescence (PL) characterization. The results showed that all the prepared ZnO samples possess a hexagonal wurtzite structure with high purity. Different particle sizes and morphologies of spheres, rods and wires were obtained depending on the preparation method used. Particle sizes obtained by the dry method are smaller than that found by the wet chemical method. The effects of both particle size and morphology on each of surface as well as optical properties, photocatalytic activity, dye/ZnO solar cell efficiency and biological activity have been studied and discussed.

  16. Rapid and repeatable fabrication of high A/R silk fibroin microneedles using thermally-drawn micromolds.

    PubMed

    Lee, JiYong; Park, Seung Hyun; Seo, Il Ho; Lee, Kang Ju; Ryu, WonHyoung

    2015-08-01

    Thermal drawing is a versatile rapid prototyping method that can freely form microneedle (MN) structures with ultra-high aspect ratio without relying on any complex and expensive process. However, it is still challenging to repeatedly produce MNs with identical shapes using this thermal drawing due to small fluctuations in processing conditions such as temperatures, drawing speeds, drawing heights, or parallelism in the drawing setup. In addition, thermal drawing is only applicable to thermoplastic materials and most natural biomaterials are incompatible with this method. Thus, we propose use of thermal drawing to fabricate master molds with high aspect ratios and replicate the shape by micromolding. In this work, high A/R MNs with various body profiles were fabricated by thermal drawing and replicated to silk fibroin (SF) MNs multiple times using micromolding. The original MN shape was precisely copied to the SF MNs. Methanol treatment enhanced the mechanical strength of SF MNs up to about 113% more depending on the treatment duration. We also demonstrated that methanol exposure time could effectively control drug release rates from SF MNs.

  17. High thermal stability and low Gilbert damping constant of CoFeB/MgO bilayer with perpendicular magnetic anisotropy by Al capping and rapid thermal annealing

    NASA Astrophysics Data System (ADS)

    Wang, Ding-Shuo; Lai, Shu-Yu; Lin, Tzu-Ying; Chien, Cheng-Wei; Ellsworth, David; Wang, Liang-Wei; Liao, Jung-Wei; Lu, Lei; Wang, Yung-Hung; Wu, Mingzhong; Lai, Chih-Huang

    2014-04-01

    We demonstrate that the magnetic anisotropy of the CoFeB/MgO bilayer can be manipulated by adding an aluminum capping layer. After rapid thermal annealing, we can achieve large perpendicular magnetic anisotropy of CoFeB with a high thermal stability factor (Δ = 72) while the Gilbert damping constant can be reduced down to only 0.011 simultaneously. The boron and residual oxygen in the bulk CoFeB layer are properly absorbed by the Al capping layer during annealing, leading to the enhanced exchange stiffness and reduced damping. The interfacial Fe-O bonding can be optimized by tuning annealing temperature and thickness of Al, resulting in enhanced perpendicular anisotropy.

  18. High thermal stability and low Gilbert damping constant of CoFeB/MgO bilayer with perpendicular magnetic anisotropy by Al capping and rapid thermal annealing

    SciTech Connect

    Wang, Ding-Shuo; Lai, Shu-Yu; Lin, Tzu-Ying; Wang, Liang-Wei; Liao, Jung-Wei; Lai, Chih-Huang; Chien, Cheng-Wei; Wang, Yung-Hung; Ellsworth, David; Lu, Lei; Wu, Mingzhong

    2014-04-07

    We demonstrate that the magnetic anisotropy of the CoFeB/MgO bilayer can be manipulated by adding an aluminum capping layer. After rapid thermal annealing, we can achieve large perpendicular magnetic anisotropy of CoFeB with a high thermal stability factor (Δ = 72) while the Gilbert damping constant can be reduced down to only 0.011 simultaneously. The boron and residual oxygen in the bulk CoFeB layer are properly absorbed by the Al capping layer during annealing, leading to the enhanced exchange stiffness and reduced damping. The interfacial Fe-O bonding can be optimized by tuning annealing temperature and thickness of Al, resulting in enhanced perpendicular anisotropy.

  19. Rapid-behaviour responses as a reliable indicator of estrogenic chemical toxicity in zebrafish juveniles.

    PubMed

    Sárria, M P; Soares, J; Vieira, M N; Castro, L Filipe C; Santos, M M; Monteiro, N M

    2011-11-01

    Whereas biochemical and molecular parameters have been well recognised as important "signposts" of individual disturbance to endocrine disrupting chemical's (EDCs) exposure, behavioural endpoints are yet greatly overlooked as a routine tool in environmental risk assessment of EDCs. However, life histories are intimately associated with numerous inter- and intra-specific interactions, which invariably depend on the performance of effective behaviours. Within fish species, one of the most important factors influencing energy turnover earlier in the development is locomotor activity. This essential trait reflects the organism's ability to generate and coordinate the metabolic energy required for both reproductive and non-reproductive behaviours. Inappropriate movement responses due to toxic effects of contaminants may ultimately impact important ecological variables. Therefore, in the present study, the swimming bursts of zebrafish juveniles exposed for 40 d to the synthetic estrogen ethinylestradiol (EE(2)), tested at environmentally relevant concentrations (nominal concentrations of 0.5, 1 and 2 ng L(-1)), were investigated in order to address the potential of rapid-behaviour patterns as an effective response indicator of estrogenic endocrine disrupting chemical's exposure. This synthetic estrogen was selected due to its high prevalence in aquatic ecosystems, ability to mimic natural estrogens and proven record of causing negative effects in fish reproduction. The behavioural responses were compared with established endpoints used in the screening of EE(2) effects at adulthood. Results indicate that zebrafish juveniles' swimming activity was significantly decreased upon EE(2) exposure. Since reduced locomotion of zebrafish may impact foraging, predator avoidance, drift and transport, and even interfere with social and reproductive behaviours, a fitness decline of wild fish populations can ultimately be hypothesized. Furthermore, behavioural endpoints were found to

  20. Chemical, isotopic, and gas compositions of selected thermal springs in Arizona, New Mexico, and Utah

    USGS Publications Warehouse

    Mariner, R.H.; Presser, T.S.; Evans, William C.

    1977-01-01

    Twenty-seven thermal springs in Arizona, New Mexico, and Utah were sampled for detailed chemical and isotopic analysis. The springs issue sodium chloride, sodium bicarbonate, or sodium mixed-anion waters of near neutral (6.2) to alkaline (9.2) pH. High concentrations of fluoride, more than 8 milligrams per liter, occur in Arizona in waters from Gillard Hot Springs, Castle Hot Springs, and the unnamed spring of Eagle Creek, and in New Mexico from springs along the Gila River. Deuterium compositions of the thermal waters cover the same range as those expected for meteoric waters in the respective areas. The chemical compositions of the thermal waters indicate that Thermo Hot Springs in Utah and Gillard Hot Springs in Arizona represent hydrothermal systems which are at temperatures higher than 125 deg C. Estimates of subsurface temperature based on the quartz and Na-K-Ca geothermometer differ by up to 60 deg C for Monroe, Joseph, Red Hill, and Crater hot springs in Utah. Similar conflicting estimates of aquifer temperature occur for Verde Hot Springs, the springs near Clifton and Coolidge Dam, in Arizona; and the warm springs near San Ysidro, Radium Hot Springs, and San Francisco Hot Springs, in New Mexico. Such disparities could result from mixing, precipitation of calcium carbonate, or perhaps appreciable concentrations of magnesium. (Woodard-USGS)

  1. Thermal and chemical degradation of inorganic membrane materials. Final report, August 1992--May 1995

    SciTech Connect

    Damle, A.S.; Krishnan, G.N.; Sanjurjo, A.; Wood, B.J.; Lau, K.H.

    1995-05-01

    SRI International conducted a theoretical and experimental program to evaluate the long-term thermal and chemical degradation of inorganic membranes that are being developed to separate the gaseous products of coal gasification. A variety of developmental efforts are underway, including a number of projects sponsored by the US Department of Energy (DOE), to improve the selectivity and permeability of porous inorganic membranes. DOE is also sponsoring efforts to extend the use of metallic membranes to new applications. Most developmental efforts have focused on hydrogen separation by inorganic membranes, which may be used to maximize hydrogen production from coal gas or to remove H{sub 2}S and NH{sub 3} contaminants via thermal or catalytic decomposition in integrated-gasification combined-cycle (IGCC) systems. Inorganic membranes that have a high separation efficiency and exhibit both thermal and chemical stability would improve the economics of power generation from coal. Membrane materials that have been investigated include glass (silica), alumina, carbon, and metals (Pd and Pt). This report describes inorganic membrane materials, long term membrane exposure tests, membrane permeation tests, coal gasifier exposure tests, conclusions, and recommendations.

  2. Thermal and chemical inactivation of indigenous Streptococcus thermophilus bacteriophages isolated from Argentinian dairy plants.

    PubMed

    Binetti, A G; Reinheimer, J A

    2000-04-01

    Thermal and chemical resistance of five autochthonal bacteriophages of Streptococcus thermophilus, isolated from Cuartirolo cheese wheys and yogurt, was investigated. Times to obtain 99% inactivation of phages (T99) at 63 degrees C and 72 degrees C in three suspension media (enriched tryptic soy broth, reconstituted commercial nonfat skim milk, and tris magnesium gelatin buffer) were determined. The thermal resistance was dependent on the phages studied but not detectable counts (<10 PFU/ml) were only achieved by heating at 90 degrees C during 5 min. The data obtained for the three assayed media did not permit verifying significant differences among them. Sodium hypochlorite (100 ppm) provided a fast inactivation of bacteriophage particles (<10 PFU/ml after 5 min). Ethanol, at concentrations of 75% and 100%, was also effective for phage destruction. Isopropanol was slightly less effective than ethanol at the same concentrations. Peracetic acid (0.15%) was also a very effective agent for phage inactivation. The results showed that these autochthonal bacteriophages were not completely inactivated neither by normal pasteurization treatments nor by some biocides commonly used in disinfection, except sodium hypochlorite and peracetic acid. The practical implications of these findings have pointed out the necessity of recognizing the importance of establishing adequate conditions to assure effective thermal and chemical treatments in dairy plants and laboratory environments.

  3. Attainable entanglement of unitary transformed thermal states in liquid-state nuclear magnetic resonance with the chemical shift

    NASA Astrophysics Data System (ADS)

    Ota, Yukihiro; Mikami, Shuji; Yoshida, Motoyuki; Ohba, Ichiro

    2007-11-01

    Yu, Brown and Chuang investigated the entanglement attainable from unitary transformed thermal states in liquid-state nuclear magnetic resonance (NMR). Their research gave insight into the role of entanglement in a liquid-state NMR quantum computer. However, they assumed that the Zeeman energy of each nuclear spin which corresponds to a qubit takes a common value for all; there is no chemical shift. In this paper, we research a model with chemical shifts and analytically derive the physical parameter region where unitary transformed thermal states are entangled, by employing the positive partial transposition (PPT) criterion with respect to any bipartition. The analysis taking account of the chemical shift reveals how the difference between quantum gates reflects on the physical parameter region where unitary transformed thermal states are entangled. In addition, we examine the distillability of unitary transformed thermal states and the effect of the chemical shifts on the boundary between the separability and the nonseparability.

  4. Design of rapid medical evacuation system for trauma patients resulting from biological and chemical terrorist attacks.

    PubMed

    Frieder, Russell S; Kumaresan, Srirangam; Sances, Anthony; Renfroe, David; Myers, Will J; Harvey, L Williams

    2006-01-01

    In the event of a large scale, biological or chemical terrorist attack it is unlikely that local emergency response organizations will have sufficient quantities of dedicated ambulances to evacuate all of the affected victims. As a potential solution to this problem, we have developed a device that can be retrofitted to a variety of government or civilian utility vehicles in order to convert them for emergency medical transport (US Pat. 7,028,351). Each installed device allows the host vehicle to safely transport either a single patient on a stretcher or multiple ambulatory patients. Additionally, each device provides a means for temporary or permanent attachment of emergency medical equipment. When not in use, the device can be collapsed to improve ease and efficiency of storage. Preliminary analyses of certain highly loaded structures on the device were carried out using known principles of solid mechanics. The analyses were carried out assuming the highest reasonable loading condition. This condition was determined to occur when the device is configured for the transport three 95(th) percentile males and 20 kg of medical equipment. This loading condition was assumed to be more severe than any that might occur due to an attendant performing CPR, or any other medical procedures, on a single supine patient. The base sections of the load bearing stretcher supports were then modeled using 3D CAD software and run through a finite element analysis (FEA) as a means to more accurately simulate the stresses that are likely to occur in the actual parts. As the device must be highly mobile, these analyses were used to confirm that the load bearing structures can be manufactured from low cost materials and still be light enough to be easily transported. Future work will include sizing and installation studies to ensure that the production version of the device can be rapidly implemented in a wide variety of private, commercial, and government utility vehicles.

  5. Mechano-chemical signaling maintains the rapid movement of Dictyostelium cells

    SciTech Connect

    Lombardi, M.L.; Knecht, D.A.; Lee, J.

    2008-05-01

    The survival of Dictyostelium cells depends on their ability to efficiently chemotax, either towards food or to form multicellular aggregates. Although the involvement of Ca{sup 2+} signaling during chemotaxis is well known, it is not clear how this regulates cell movement. Previously, fish epithelial keratocytes have been shown to display transient increases in intracellular calcium ([Ca{sup 2+}]{sub i}) that are mediated by stretch-activated calcium channels (SACs), which play a role in retraction of the cell body [J. Lee, A. Ishihara, G. Oxford, B. Johnson, and K. Jacobson, Regulation of cell movement is mediated by stretch-activated calcium channels. Nature, 1999. 400(6742): p. 382-6.]. To investigate the involvement of SACs in Dictyostelium movement we performed high resolution calcium imaging in wild-type (NC4A2) Dictyostelium cells to detect changes in [Ca{sup 2+}]{sub i}. We observed small, brief, Ca{sup 2+} transients in randomly moving wild-type cells that were dependent on both intracellular and extracellular sources of calcium. Treatment of cells with the SAC blocker gadolinium (Gd{sup 3+}) inhibited transients and decreased cell speed, consistent with the involvement of SACs in regulating Dictyostelium motility. Additional support for SAC activity was given by the increase in frequency of Ca{sup 2+} transients when Dictyostelium cells were moving on a more adhesive substratum or when they were mechanically stretched. We conclude that mechano-chemical signaling via SACs plays a major role in maintaining the rapid movement of Dictyostelium cells.

  6. Microwave-assisted chemical insertion: a rapid technique for screening cathodes for Mg-ion batteries

    SciTech Connect

    Kaveevivitchai, Watchareeya; Huq, Ashfia; Manthiram, Arumugam

    2016-12-19

    We report an ultrafast microwave-assisted solvothermal method for chemical insertion of Mg2+ ions into host materials using magnesium acetate [Mg(CH3COO)2] as a metal-ion source and diethylene glycol (DEG) as a reducing agent. For instance, up to 3 Mg ions per formula unit of a microporous host framework Mo2.5+yVO9+z could be inserted in as little as 30 min at 170–195 °C in air. This process is superior to the traditional method which involves the use of organometallic reagents, such as di-n-butylmagnesium [(C4H9)2Mg] and magnesium bis(2,6-di-tert-butylphenoxide) [Mg-(O-2,6-But2C6H3)2], and requires an inert atmosphere with extremely long reaction times. Considering the lack of robust electrolytes for Mg-ion batteries, this facile approach can be readily used as a rapid screening technique to identify potential Mg-ion electrode hosts without the necessity of fabricating electrodes and assembling electrochemical cells. Due to the mild reaction conditions, the overall structure and morphology of the Mg-ion inserted products are maintained and the compounds can be used successfully as a cathode in Mg-ion batteries. The combined synchrotron X-ray and neutron diffraction Rietveld analysis reveals the structure of the Mg-inserted compounds and gives an insight into the interactions between the Mg ions and the open-tunnel host framework.

  7. Microwave-Accelerated Rapid, Chemical Oxidant-Free, Material-Independent Surface Chemistry of Poly(dopamine).

    PubMed

    Lee, Mihyun; Lee, Si-Hwa; Oh, Il-Kwon; Lee, Haeshin

    2017-01-01

    A simple strategy for the rapid preparation of multifunctional polydopamine (pDA) coatings is demonstrated. Microwave irradiation of the coating solution enables the formation of a ≈18 nm thick, genuine pDA coating in 15 min, which is ≈18 times faster than conventional coating. The acceleration effect results from the radical generation and temperature increase, which facilitate thermally accelerated radical polymerization of dopamine.

  8. Changes in the Chemical Composition and Decay Resistance of Thermally-Modified Hevea brasiliensis Wood

    PubMed Central

    2016-01-01

    In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood. PMID:26986200

  9. Characterisation of waste derived biochar added biocomposites: chemical and thermal modifications.

    PubMed

    Das, Oisik; Sarmah, Ajit K; Zujovic, Zoran; Bhattacharyya, Debes

    2016-04-15

    A step towards sustainability was taken by incorporating waste based pyrolysed biochar in wood and polypropylene biocomposites. The effect of biochar particles on the chemistry and thermal makeup of the composites was determined by characterising them through an array of characterisation techniques such as 3D optical profiling, X-ray diffraction, transmission electron microscopy, electron spin/nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. It was observed that addition of biochar increased the presence of free radicals in the composite while also improving its thermal conductivity. Biochar particles did not interfere with the melting behaviour of polymer in the thermal regime. However, wood and biochar acted as nucleation agents consequently increasing the crystallisation temperature. The crystal structure of polypropylene was not disrupted by biochar inclusion in composite. Transmission electron microscopy images illustrated the aggregated nature of the biochar particles at higher loading levels. Nuclear magnetic resonance studies revealed the aromatic nature of biochar and the broadening of peak intensities of composites with increasing biochar levels due to its amorphous nature and presence of free radicals. Thus, this insight into the chemical and thermal modification of biochar added composites would allow effective engineering to optimise their properties while simultaneously utilising wastes.

  10. Chemical and isotopic characteristics of thermal fluids in the Long Valley caldera lateral flow system, California

    SciTech Connect

    Shevenell, L.; Goff, F.; Grigsby, C.O.; Janik, C.J.; Trujillo, P.E. Jr.; Counce, D.

    1987-01-01

    Chemical and isotopic data of thermal waters in Long Valley caldera have been used to identify both the origins and characteristics of the fluids and to evaluate mixing and boiling processes occurring within the lateral flow system of the caldera. Recharge to the Long Valley geothermal system occurs in the western part of the caldera with the water being heated at depth and flowing laterally eastward in the subsurface. The lateral flow system was recently intersected by the Shady Rest Continental Scientific Drilling Program (CSDP) corehole at 335 m (1100 ft) with fluids in this 202/sup 0/C zone being more concentrated than non-boiled fluids to the east. As the Na-K-HCO/sub 3/-Cl thermal fluids flow eastward, they are increasingly mixed with isotopically depleted, dilute groundwaters similar to cold waters east of Lake Crowley. Near surface boiling of Casa Diablo well fluids at 100/sup 0/C forms waters with the compositions of Colton and Casa Diablo hot springs. Waters to the east of the Casa Diablo area are mixtures of meteoric water and boiled thermal fluids with a composition close to that of Colton Hot Spring. There is no correlation between /sup 3/H and /sup 36/Cl in thermal fluids or between these components and conservative species, and it appears that cold fluids involved in mixing must be relatively old waters, low in both meteoric /sup 3/H and /sup 36/Cl.

  11. Changes in the Chemical Composition and Decay Resistance of Thermally-Modified Hevea brasiliensis Wood.

    PubMed

    Severo, Elias Taylor Durgante; Calonego, Fred Willians; Sansígolo, Cláudio Angeli; Bond, Brian

    2016-01-01

    In this study the effect of thermal treatment on the equilibrium moisture content, chemical composition and biological resistance to decay fungi of juvenile and mature Hevea brasiliensis wood (rubber wood) was evaluated. Samples were taken from a 53-year-old rubber wood plantation located in Tabapuã, Sao Paulo, Brazil. The samples were thermally-modified at 180°C, 200°C and 220°C. Results indicate that the thermal modification caused: (1) a significant increase in the extractive content and proportional increase in the lignin content at 220°C; (2) a significant decrease in the equilibrium moisture content, holocelluloses, arabinose, galactose and xylose content, but no change in glucose content; and (3) a significant increase in wood decay resistance against both Pycnoporus sanguineus (L.) Murrill and Gloeophyllum trabeum (Pers.) Murrill decay fungi. The greatest decay resistance was achieved from treatment at 220°C which resulted in a change in wood decay resistance class from moderately resistant to resistant. Finally, this study also demonstrated that the influence of thermal treatment in mature wood was lower than in juvenile wood.

  12. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    SciTech Connect

    Alam, M. T.; Haque, M. A.; Bresnehan, M. S.; Robinson, J. A.

    2014-01-06

    Thermal conductivity of freestanding 10 nm and 20 nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100 ± 10 W m{sup −1} K{sup −1}, is lower than the bulk basal plane value (390 W m{sup −1} K{sup −1}) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

  13. Chemical and thermal analysis of biomass ash from wooden chips and wheat straw combustion

    NASA Astrophysics Data System (ADS)

    Jankovský, Ondřej; Sedmidubský, David; Luxa, Jan; Bartůněk, Vilém; Záleská, Martina; Pavlíková, Milena; Pavlík, Zbyšek

    2017-07-01

    In this paper, we would like to demonstrate that biomass ash with appropriate composition can be used for the fabrication of high performance composites. Biomass ash from wooden chips and packed wheat straw was characterized using XRF and XRD. While the biomass ash contained high amount of carbon, it was thermally treated in order to reduce carbon content. The chemical and phase composition of treated biomass ash was again analyzed in detail by XRF and XRD. Moreover, the thermal treatment process was analyzed using STA. In the next step, the pozzolanic activity was analyzed using Frattini test. Potentiometric method was used for pH measurement. Since the both biomass ashes were pozzolana active, they are potentially suitable as a pozzolana active admixture in the cement, lime and alkali activated aluminosilicate composites.

  14. Thermal history, chemical composition and relationship of comets to the origin of life

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Leschine, S. B.; Schloerb, F. P.

    1980-01-01

    The role of thermal processes in determining the chemical composition of comets is considered, and implications of possible cometary constituents for the origin and evolution of life on earth are discussed. It is shown that the inclusion of short-lived Al-26 from a nearby supernova explosion into cometary nuclei could lead to comets with surfaces cool enough to retain H2O and interiors warm enough for thermal processing to occur, with the production of complex organic molecules such as amino acids and nucleic acid bases. It is thus suggested that comets may have played a part in seeding the primitive earth with biological polymers capable of self-replication or of evolving towards that capability, and may even be responsible for the subsequent introduction of organic material capable of infecting already existing cells.

  15. Vertical graphene nanosheets synthesized by thermal chemical vapor deposition and the field emission properties

    NASA Astrophysics Data System (ADS)

    Guo, Xin; Qin, Shengchun; Bai, Shuai; Yue, Hongwei; Li, Yali; Chen, Qiang; Li, Junshuai; He, Deyan

    2016-09-01

    In this paper, we explored synthesis of vertical graphene nanosheets (VGNs) by thermal chemical vapor deposition (CVD). Through optimizing the experimental condition, growth of well aligned VGNs with uniform morphologies on nickel-coated stainless steel (SS) was realized for the first time by thermal CVD. In the meantime, influence of growth parameters on the VGN morphology was understood based on the balancing between the concentration and kinetic energy of carbon-containing radicals. Structural characterizations demonstrate that the achieved VGNs are normally composed of several graphene layers and less corrugated compared to the ones synthesized by other approaches, e.g. plasma enhanced (PE) CVD. The field emission measurement indicates that the VGNs exhibit relatively stable field emission and a field enhancement factor of about 1470, which is comparable to the values of VGNs prepared by PECVD can be achieved.

  16. Finite volume model for forced flow/thermal gradient chemical vapor infiltration

    SciTech Connect

    Starr, T.L.; Smith, A.W.

    1991-03-01

    The forced flow/thermal gradient chemical vapor infiltration process (FCVI) has proven to be a successfully technique for fabrication of ceramic matrix composites. It is particularly attractive for thick components which cannot be fabricated using the conventional, isothermal method (ICVI). Although it offers processing times that are at least an order of magnitude shorter than ICVI, FCVI has not been used to fabricate parts of complex geometry and is perceived by many to be unsuitable for such components. The major concern is that selection and control of the flow pattern and thermal profile for optimum infiltration can be a difficult and costly exercise. In order to reduce this effort, we are developing a computer model for FCVI that simulates the densification process for given component geometry, reactor configuration and operating parameters. Used by a process engineer, this model can dramatically reduce the experimental effort needed to obtain uniform densification.

  17. Magnesium isotope fractionation in silicate melts by chemical and thermal diffusion

    NASA Astrophysics Data System (ADS)

    Richter, Frank M.; Watson, E. Bruce; Mendybaev, Ruslan A.; Teng, Fang-Zhen; Janney, Philip E.

    2008-01-01

    Two types of laboratory experiments were used to quantify magnesium isotopic fractionations associated with chemical and thermal (Soret) diffusion in silicate liquids. Chemical diffusion couples juxtaposing a molten natural basalt (SUNY MORB) and a molten natural rhyolite (Lake County Obsidian) were run in a piston cylinder apparatus and used to determine the isotopic fractionation of magnesium as it diffused from molten basalt to molten rhyolite. The thermal diffusion experiments were also run in a piston cylinder apparatus but with a sample made entirely of molten SUNY MORB displaced from the hotspot of the assembly furnace so that the sample would have a temperature difference of about 100-200 °C from one end to the other. The chemical diffusion experiments showed fractionations of 26Mg/ 24Mg by as much as 7‰, which resulted in an estimate for the mass dependence of the self-diffusion coefficients of the magnesium isotopes corresponding to D/D=(24/26)β with β = 0.05. The thermal diffusion experiments showed that a temperature difference of about 100 °C resulted in the MgO, CaO, and FeO components of the basalt becoming slightly enriched by about 1 wt% in the colder end while SiO 2 was enriched by several wt% in the hotter end. The temperature gradient also fractionated the magnesium isotopes. A temperature difference of about 150 °C produced an 8‰ enrichment of 26Mg/ 24Mg at the colder end relative to the hotter end. The magnesium isotopic fractionation as a function of temperature in molten basalt corresponds to 3.6 × 10 -2‰/°C/amu.

  18. Amniotic membrane transplantation in treatment of persistent corneal ulceration after severe chemical and thermal eye injuries.

    PubMed

    Iakimenko, Stanislav A; Buznyk, Oleksiy I; Rymgayllo-Jankowska, Beata

    2013-01-01

    To analyze results of amniotic membrane transplantation (AMT) in treatment of corneal ulceration after severe chemical and thermal injuries. Analysis of 55 AMT in 53 patients (53 eyes) with corneal ulceration and limbal deficiency 180-360° of the limbus after grade 4-6 (Dua classification, 2001) chemical and thermal injuries was performed. Mean terms of the operation were 46.1 ± 46.4 days after the injury (range 8-181 days). Preoperative visual acuity (VA) was <0.01 in 33/53 patients (62.3%). Mean follow-up period was 8.8 ± 10.1 months (range 1.5-46 months). Further corneal ulceration was prevented in 54/55 cases (98.1%), cornea epithelialized after 42/55 AMT (76.3%). Mean terms of corneal epithelialization were 24.2 ± 26.7 days after AMT (range 6-123 days). Corneal defect recurred in 3/42 successful cases (7.1%). Limbal deficiency of different extent with subsequent corneal conjunctivalization developed in all successful patients. The VA was ≥0.01 (range 0.01-1.0) in 23/42 patients (54.8%) with corneal epithelialization. The VA at the last visit was improved on 2 and more lines on the eye chart compared to preoperative VA in 15/42 patients with corneal epithelialization (35.7%), did not change in 18/42 successful patients (42.9%), and decreased on one line in 9/42 of these patients (26.2%). Symblepharon developed in 23/42 successful patients (54.7%). Amniotic membrane transplantation may stop ulceration and promote corneal epithelialization in the majority of patients with the most severe chemical or thermal eye injuries in case of timely application of the operation and adequate fixation of the AMT graft.

  19. Food availability promotes rapid recovery from thermal stress in a scleractinian coral

    NASA Astrophysics Data System (ADS)

    Connolly, S. R.; Lopez-Yglesias, M. A.; Anthony, K. R. N.

    2012-12-01

    Bleaching in corals due to environmental stress represents a loss of energy intake often leading to an increase in mortality risk. Successful coral recovery from severe bleaching events may depend on the rate of replenishment of algal symbiont populations following the period of thermal stress, the supply of an alternative food source, or both. Here, we explore the role of food availability in promoting the survival and recovery of a common coral ( Acropora intermedia) following acute experimentally induced thermal stress. Fed corals were provided with live rotifers daily, to maintain densities of zooplankton in tanks that are typical of coral reefs. After a 6-week acclimation phase, heated corals were subjected to a +4 °C thermal anomaly for a 7-day period (bleaching phase) then temperatures were returned to normal for a further 2 weeks (recovery phase). Results demonstrated that heated corals had higher survival when they were provided with heterotrophic food. Fed corals experienced reduced loss of chlorophyll a, relative to unfed corals. During the recovery phase, both fed and unfed corals recovered within a few days; however, fed corals recovered to pre-bleaching phase levels of chlorophyll a, whereas unfed corals stabilized approximately one-third below this level. Protein levels of fed corals declined markedly during the bleaching phase, but recovered all of their losses by the end of the recovery phase. In contrast, unfed corals had low protein levels that were maintained throughout the experiment. To the extent that these results are representative of corals' responses to thermal anomalies in nature, the findings imply that availability of particulate food matter has the potential to increase corals' capacity to survive thermally induced bleaching and to ameliorate its sub-lethal effects. They also support the hypothesis that different rates of heterotrophy are an important determinant of variation in resilience to thermal stress among reef environments.

  20. P80 SRM low torque flex-seal development - thermal and chemical modeling of molding process

    NASA Astrophysics Data System (ADS)

    Descamps, C.; Gautronneau, E.; Rousseau, G.; Daurat, M.

    2009-09-01

    The development of the flex-seal component of the P80 nozzle gave the opportunity to set up new design and manufacturing process methods. Due to the short development lead time required by VEGA program, the usual manufacturing iterative tests work flow, which is usually time consuming, had to be enhanced in order to use a more predictive approach. A newly refined rubber vulcanization description was built up and identified on laboratory samples. This chemical model was implemented in a thermal analysis code. The complete model successfully supports the manufacturing processes. These activities were conducted with the support of ESA/CNES Research & Technologies and DGA (General Delegation for Armament).

  1. Catalytically enhanced thermal decomposition of chemically grown silicon oxide layers on Si(001)

    NASA Astrophysics Data System (ADS)

    Leroy, F.; Passanante, T.; Cheynis, F.; Curiotto, S.; Bussmann, E. B.; Müller, P.

    2016-03-01

    The thermal decomposition of Si dioxide layers formed by wet chemical treatment on Si(001) has been studied by low-energy electron microscopy. Independent nucleations of voids occur into the Si oxide layers that open by reaction at the void periphery. Depending on the voids, the reaction rates exhibit large differences via the occurrence of a nonlinear growth of the void radius. This non-steady state regime is attributed to the accumulation of defects and silicon hydroxyl species at the SiO2/Si interface that enhances the silicon oxide decomposition at the void periphery.

  2. Coupled thermal/chemical/mechanical modeling of energetic materials in ALE3D

    NASA Technical Reports Server (NTRS)

    Nichols, A. L.; Couch, R.; Maltby, J. D.; McCallen, R. C.; Otero, I.

    1996-01-01

    We must improve our ability to model the response of energetic materials to thermal stimuli and the processes involved in the energetic response. We have developed and used a time step option to efficiently and accurately compute the hours that the energetic material can take to react. Since on these longer film scales, materials can be expected to have significant motion, it is even more important to provide high-order advection for all components, including the chemical species. We show an example cook-off problem to illustrate these capabilities.

  3. Catalytically enhanced thermal decomposition of chemically grown silicon oxide layers on Si(001)

    SciTech Connect

    Leroy, F. Passanante, T.; Cheynis, F.; Curiotto, S.; Bussmann, E. B.; Müller, P.

    2016-03-14

    The thermal decomposition of Si dioxide layers formed by wet chemical treatment on Si(001) has been studied by low-energy electron microscopy. Independent nucleations of voids occur into the Si oxide layers that open by reaction at the void periphery. Depending on the voids, the reaction rates exhibit large differences via the occurrence of a nonlinear growth of the void radius. This non-steady state regime is attributed to the accumulation of defects and silicon hydroxyl species at the SiO{sub 2}/Si interface that enhances the silicon oxide decomposition at the void periphery.

  4. Comparing rapid-screening and standard toxicity assays to assess known chemical contamination at a hazardous waste site

    SciTech Connect

    Martino, L.; Swigert, J.; Roberts, C.

    1995-12-31

    The thrust to streamline the Superfund site investigation/remediation program makes it critical for site investigators to utilize rapid screening methodologies to facilitate decision-making. However, screening methodologies providing information upon which decision-making is based must not only be rapid but also scientifically valid. This presentation compares and contrasts two rapid screening toxicity assessments, the Daphnia magna IQ Toxicity Test {trademark} and Microtox{trademark}, to a battery of standard aquatic toxicity tests using Lemna, Rana, Pimephales, Selenastruni and Ceriodaphnia. Chemical analysis of test water samples provided evidence of potential toxicological risk associated with the test samples. The study site was J-Field, Aberdeen Proving Ground, Maryland, a federal facility listed on the National Priority List that used to test and/or dispose of high explosives and chemical warfare agents in open pits or fields. Surface water samples from 20 sites were collected and used in the toxicity assessments. Water samples also were analyzed for explosives, chemical surety degradation compounds, Target Analyte List (inorganics), Target Compound List (organics) and selected pesticides and PCBs. The Microtox{trademark} assay did not reveal any toxicity present in the samples analyzed. Correlation analyses showed only slight correlation between the Daphnia magna IQ{trademark} assay and the standard 48-hour toxicity test. No correlation existed between the Microtox{trademark} assay and the aquatic toxicity tests. Results are discussed in light of the expected risk of the chemicals known to be present and the outcome of the toxicity tests.

  5. Rapid warming at the Palaeocene-Eocene Thermal Maximum drives rapid hydrate dissociation but only modest and delayed methane release to the ocean

    NASA Astrophysics Data System (ADS)

    Minshull, Tim; Marin-Moreno, Hector; Wilson, Paul; Armstrong McKay, David

    2016-04-01

    During the Palaeocene-Eocene Thermal Maximum (PETM), the carbon isotopic signature δ13C of the ocean-atmosphere system decreased abruptly - the record in deep sea benthic foraminifera shows an excursion of at least 2.5 to 3.0 ‰ VPDB. This global carbon isotope excursion (CIE) has been attributed to large-scale methane hydrate dissociation in response to rapid ocean warming. There is increasing evidence for warming-induced hydrate dissociation in the modern ocean and the PETM may represent an analogue for this process. We ran a thermohydraulic modeling code to simulate hydrate dissociation due to ocean warming for a range of possible PETM scenarios. Our results show that hydrate dissociation in response to such warming is rapid but methane release to the ocean is modest, and delayed by hundreds to thousands of years by transport processes through the hydrate stability field. In our simulations most of the dissociated hydrate methane remains beneath the seabed, either in solution or as free gas below the irreducible gas saturation, and the small fraction (≤0.13) released to the ocean is delivered over several kyr. We conclude that hydrate dissociation cannot have been largely responsible for the CIE unless the late Palaeocene hydrate inventory greatly exceeded most current estimates.

  6. BOND STRENGTH OF HARD CHAIRSIDE RELINE RESINS TO A RAPID POLYMERIZING DENTURE BASE RESIN BEFORE AND AFTER THERMAL CYCLING

    PubMed Central

    Neppelenbroek, Karin Hermana; Pavarina, Ana Cláudia; Gomes, Mauricio Neves; Machado, Ana Lucia; Vergani, Carlos Eduardo

    2006-01-01

    Purpose: This study assessed the shear bond strength of 4 hard chairside reline resins (Kooliner, Tokuso Rebase Fast, Duraliner II, Ufi Gel Hard) to a rapid polymerizing denture base resin (QC-20) processed using 2 polymerization cycles (A or B), before and after thermal cycling. Materials and Methods: Cylinders (3.5 mm x 5.0 mm) of the reline resins were bonded to cylinders of QC-20 polymerized using cycle A (boiling water–20 minutes) or B (boiling water; remove heat-20 minutes; boiling water–20 minutes). For each reline resin/polymerization cycle combination, 10 specimens (groups CAt e CBt) were thermally cycled (5 and 55 °C; dwell time 30 seconds; 2,000 cycles); the other 10 were tested without thermal cycling (groups CAwt ad CBwt). Shear bond tests (0.5 mm/min) were performed on the specimens and the failure mode was assessed. Data were analyzed by 3-way ANOVA and Newman-Keuls post-hoc test (α=.05). Results: QC-20 resin demonstrated the lowest bond strengths among the reline materials (P<.05) and mainly failed cohesively. Overall, the bond strength of the hard chairside reline resins were similar (10.09±1.40 to 15.17±1.73 MPa) and most of the failures were adhesive/cohesive (mixed mode). However, Ufi Gel Hard bonded to QC-20 polymerized using cycle A and not thermally cycled showed the highest bond strength (P<.001). When Tokuso Rebase Fast and Duraliner II were bonded to QC-20 resin polymerized using cycle A, the bond strength was increased (P=.043) after thermal cycling. Conclusions: QC-20 displayed the lowest bond strength values in all groups. In general, the bond strengths of the hard chairside reline resins were comparable and not affected by polymerization cycle of QC-20 resin and thermal cycling. PMID:19089244

  7. Conservation equations and physical models for hypersonic air flows in thermal and chemical nonequilibrium

    NASA Technical Reports Server (NTRS)

    Gnoffo, Peter A.; Gupta, Roop N.; Shinn, Judy L.

    1989-01-01

    The conservation equations for simulating hypersonic flows in thermal and chemical nonequilibrium and details of the associated physical models are presented. These details include the curve fits used for defining thermodynamic properties of the 11 species air model, curve fits for collision cross sections, expressions for transport properties, the chemical kinetics models, and the vibrational and electronic energy relaxation models. The expressions are formulated in the context of either a two or three temperature model. Greater emphasis is placed on the two temperature model in which it is assumed that the translational and rotational energy models are in equilibrium at the translational temperature, T, and the vibrational, electronic, and electron translational energy modes are in equilibrium at the vibrational temperature, T sub v. The eigenvalues and eigenvectors associated with the Jacobian of the flux vector are also presented in order to accommodate the upwind based numerical solutions of the complete equation set.

  8. Thermal stresses in chemically hardening elastic media with application to the molding process

    NASA Technical Reports Server (NTRS)

    Levitsky, M.; Shaffer, B. W.

    1974-01-01

    A method has been formulated for the determination of thermal stresses in materials which harden in the presence of an exothermic chemical reaction. Hardening is described by the transformation of the material from an inviscid liquid-like state into an elastic solid, where intermediate states consist of a mixture of the two, in a ratio which is determined by the degree of chemical reaction. The method is illustrated in terms of an infinite slab cast between two rigid mold surfaces. It is found that the stress component normal to the slab surfaces vanishes in the residual state, so that removal of the slab from the mold leaves the remaining residual stress unchanged. On the other hand, the residual stress component parallel to the slab surfaces does not vanish. Its distribution is described as a function of the parameters of the hardening process.

  9. Enhanced electron-phonon coupling and critical current density in rapid thermally quenched MgB2 bulk samples

    NASA Astrophysics Data System (ADS)

    Suraj, T. S.; Muralidhar, M.; Sethupathi, K.; Rao, M. S. Ramachandra; Murakami, M.

    2017-08-01

    We report Rapid Thermal Quenching (RTQ) studies on MgB2 samples from optimized sintering temperature of 800 °C down to liquid nitrogen temperature with different sintering duration. Superior electron-phonon coupling strength (λe -E2g ) , critical current density (Jc) and irreversibility fields (Hirr) compared to doped MgB2 were observed without compromising transition temperature Tc. Structural studies showed a contraction of the unit cell due to thermal stress induced by RTQ. Enhanced λe -E2g evaluated from line width, and phonon frequency of Raman spectra using Allen equation was consistent with structural and magnetic studies. Microstructural analysis showed a decrease in grain size resulting in increased Jc and Hirr.

  10. An Approach to Rapid Calculation of Temperature Change in Tissue Using Spatial Filters to Approximate Effects of Thermal Conduction

    PubMed Central

    Carluccio, Giuseppe; Erricolo, Danilo; Oh, Sukhoon

    2014-01-01

    We present an approach to performing rapid calculations of temperature within tissue by interleaving, at regular time intervals, 1) an analytical solution to the Pennes (or other desired) bioheat equation excluding the term for thermal conduction and 2) application of a spatial filter to approximate the effects of thermal conduction. Here, the basic approach is presented with attention to filter design. The method is applied to a few different cases relevant to magnetic resonance imaging, and results are compared to those from a full finite-difference (FD) implementation of the Pennes bio-heat equation. It is seen that results of the proposed method are in reasonable agreement with those of the FD approach, with about 15% difference in the calculated maximum temperature increase, but are calculated in a fraction of the time, requiring less than 2% of the calculation time for the FD approach in the cases evaluated. PMID:23358947

  11. Rapid estimation of glucosinolate thermal degradation rate constants in leaves of Chinese kale and broccoli (Brassica oleracea) in two seasons.

    PubMed

    Hennig, Kristin; Verkerk, Ruud; Bonnema, Guusje; Dekker, Matthijs

    2012-08-15

    Kinetic modeling was used as a tool to quantitatively estimate glucosinolate thermal degradation rate constants. Literature shows that thermal degradation rates differ in different vegetables. Well-characterized plant material, leaves of broccoli and Chinese kale plants grown in two seasons, was used in the study. It was shown that a first-order reaction is appropriate to model glucosinolate degradation independent from the season. No difference in degradation rate constants of structurally identical glucosinolates was found between broccoli and Chinese kale leaves when grown in the same season. However, glucosinolate degradation rate constants were highly affected by the season (20-80% increase in spring compared to autumn). These results suggest that differences in glucosinolate degradation rate constants can be due to variation in environmental as well as genetic factors. Furthermore, a methodology to estimate rate constants rapidly is provided to enable the analysis of high sample numbers for future studies.

  12. Formation of VO{sub 2} by rapid thermal annealing and cooling of sputtered vanadium thin films

    SciTech Connect

    Ba, Cheikhou O. F. Fortin, Vincent; Bah, Souleymane T.; Vallée, Réal; Pandurang, Ashrit

    2016-05-15

    Sputtered vanadium-rich films were subjected to rapid thermal annealing-cooling (RTAC) in air to produce vanadium dioxide (VO{sub 2}) thin films with thermochromic switching behavior. High heating and cooling rates in the thermal oxidation process provided an increased ability to control the film's microstructure. X-ray diffraction patterns of the films revealed less intense VO{sub 2} peaks compared to traditional polycrystalline samples fabricated with a standard (slower) cooling time. Such films also exhibit a high optical switching reflectance contrast, unlike the traditional polycrystalline VO{sub 2} thin films, which show a more pronounced transmittance switching. The authors find that the RTAC process stabilizes the VO{sub 2} (M2) metastable phase, enabling a rutile-semiconductor phase transition (R-M2), followed by a semiconductor–semiconductor phase transition (M2-M1).

  13. Thermal and fast neutron detection in chemical vapor deposition single-crystal diamond detectors

    SciTech Connect

    Almaviva, S.; Marinelli, M.; Milani, E.; Prestopino, G.; Tucciarone, A.; Verona, C.; Verona-Rinati, G.; Angelone, M.; Lattanzi, D.; Pillon, M.; Montereali, R. M.; Vincenti, M. A.

    2008-03-01

    Recently, a compact solid-state neutron detector capable of simultaneously detecting thermal and fast neutrons was proposed [M. Marinelli et al., Appl. Phys. Lett. 89, 143509 (2006)]. Its design is based on a p-type/intrinsic/metal layered structure obtained by Microwave Plasma Chemical Vapor Deposition (CVD) of homoepitaxial diamond followed by thermal evaporation of an Al contact and a {sup 6}LiF converting layer. Fast neutrons are directly detected in the CVD diamond bulk, since they have enough energy to produce the {sup 12}C(n,{alpha}){sup 9}Be reaction in diamond. Thermal neutrons are instead converted into charged particles in the {sup 6}LiF layer through the {sup 6}Li(n,{alpha})T nuclear reaction. These charged particles are then detected in the diamond layer. The thickness of the {sup 6}LiF converting layer and the CVD diamond sensing layer affect the counting efficiency and energy resolution of the detector both for low- (thermal) and high-energy neutrons. An analysis is carried out on the dynamics of the {sup 6}Li(n,{alpha})T and the {sup 12}C(n,{alpha}){sup 9}Be reactions products, and the distribution of the energy released inside the sensitive layer is calculated. The detector counting efficiency and energy resolution were accordingly derived as a function of the thickness of the {sup 6}LiF and CVD diamond layers, both for thermal and fast neutrons, thus allowing us to choose the optimum detector design for any particular application. Comparison with experimental results is also reported.

  14. Enhanced Formation of Si Nanocrystals in SiO2 by Light-Filtering Rapid Thermal Annealing

    NASA Astrophysics Data System (ADS)

    Chen, Xiaobo; Chen, Guangping

    2015-04-01

    In this work, silicon-rich oxide (SRO) films with designed thickness of 100 nm were deposited by a bipolar pulse and radio frequency magnetron co-sputtering. For comparison, the samples were then treated in a nitrogen atmosphere by conventional rapid thermal annealing (CRTA) or light-filtering rapid thermal annealing (LRTA) at 900-1100°C for 2 min. Raman spectra, grazing incident X-ray diffraction (XRD), transmission electron microscopy (TEM), Hall measurements, and current density-voltage measurements were carried out to analyze the microstructural and electrical properties of samples. Compared with the control sample using CRTA method, the crystalline volume fraction and number density of Si nanocrystals (SiNCs) in silicon oxide prepared by LRTA were greatly increased. The quantum effects of the short wave-length light (less than 800 nm) of these tungsten halogen lamps during the rapid thermal annealing process have negative effects on the formation of SiNCs in SiO2 films. SiNCs with crystal volume fraction of 73%, average size of 2.53 nm, and number density of 1.1 × 1012 cm-2 embedded in the amorphous SiO2 matrix can be formed by LRTA at 1100°C. Enhancement of more than one order of magnitude in conductivity and higher current density were obtained from the LRTA annealed sample compared to the CRTA annealed sample. The improvements in conductivity and current density were attributed to the high density SiNCs. Our results show that the LRTA method is a suitable annealing tool for the formation of SiNC in thin SiOx films.

  15. New rapid-curing, stable polyimide polymers with high-temperature strength and thermal stability

    NASA Technical Reports Server (NTRS)

    Burns, E. A.; Jones, J. F.; Kendrick, W. R.; Lubowitz, H. R.; Thorpe, R. S.; Wilson, E. R.

    1969-01-01

    Additive-type polymerization reaction forms thermally stable polyimide polymers, thereby eliminating the volatile matter attendant with the condensation reaction. It is based on the utilization of reactive alicyclic rings positioned on the ends of polyimide prepolymers having relatively low molecular weights.

  16. Solar photo-thermal catalytic reactions to produce high value chemicals

    SciTech Connect

    Prengle, Jr, H W; Wentworth, W E

    1992-04-01

    This report presents a summary of the research work accomplished to date on the utilization of solar photo-thermal energy to convert low cost chemical feedstocks into high $-value chemical products. The rationale is that the solar IR-VIS-UV spectrum is unique, supplying endothermic reaction energy as well as VIS-UV for photochemical activation. Chemical market analysis and product price distribution focused attention on speciality chemicals with prices >$1.00/lb, and a synthesis sequence of n-paraffins to aromatics to partial oxidized products. The experimental work has demonstrated that enhanced reaction effects result from VIS-UV irradiation of catalytically active V2O5/SiO2. Experiments of the past year have been on dehydrogenation and dehydrocyclization of n-paraffins to olefins and aromatics with preference for the latter. Recent results using n-hexane produced 95% conversion with 56% benzene; it is speculated that aromatic yield should reach {approximately}70% by further optimization. Pilot- and commercial-scale reactor configurations have been examined; the odds-on-favorite being a shallow fluid-bed of catalyst with incident radiation from the top. Sequencing for maximum cost effectiveness would be day-time endothermic followed by night-time exothermic reactions to produce the products.

  17. Synthesis and characterization of injectable, thermally and chemically gelable, amphiphilic poly(N-isopropylacrylamide)-based macromers.

    PubMed

    Hacker, Michael C; Klouda, Leda; Ma, Brandy B; Kretlow, James D; Mikos, Antonios G

    2008-06-01

    In this study, we synthesized and characterized a series of macromers based on poly( N-isopropylacrylamide) that undergo thermally induced physical gelation and, following chemical modification, can be chemically cross-linked. Macromers with number average molecular weights typically ranging from 2000-3500 Da were synthesized via free radical polymerization from, in addition to N-isopropylacrylamide, pentaerythritol diacrylate monostearate, a bifunctional monomer containing a long hydrophobic chain, acrylamide, a hydrophilic monomer, and hydroxyethyl acrylate, a hydrophilic monomer used to provide hydroxyl groups for further chemical modification. Results indicated that the hydrophobic-hydrophilic balance achieved by varying the relative concentrations of comonomers used during synthesis was an important parameter in controlling the transition temperature of the macromers in solution and stability of the resultant gels. Storage moduli of the macromers increased over 4 orders of magnitude once gelation occurred above the transition temperature. Furthermore, chemical cross-linking of these macromers resulted in gels with increased stability compared to uncross-linked controls. These results demonstrate the feasibility of synthesizing poly( N-isopropylacrylamide)-based macromers that undergo tandem gelation and establish key criteria relating to the transition temperature and stability of these materials. The data suggest that these materials may be attractive substrates for tissue engineering and cellular delivery applications as the combination of mechanistically independent gelation techniques used in tandem may offer superior materials with regard to gelation kinetics and stability.

  18. Solar photo-thermal catalytic reactions to produce high value chemicals

    SciTech Connect

    Prengle, H.W. Jr.; Wentworth, W.E. )

    1992-04-01

    This report presents a summary of the research work accomplished to date on the utilization of solar photo-thermal energy to convert low cost chemical feedstocks into high $-value chemical products. The rationale is that the solar IR-VIS-UV spectrum is unique, supplying endothermic reaction energy as well as VIS-UV for photochemical activation. Chemical market analysis and product price distribution focused attention on speciality chemicals with prices >$1.00/lb, and a synthesis sequence of n-paraffins to aromatics to partial oxidized products. The experimental work has demonstrated that enhanced reaction effects result from VIS-UV irradiation of catalytically active V2O5/SiO2. Experiments of the past year have been on dehydrogenation and dehydrocyclization of n-paraffins to olefins and aromatics with preference for the latter. Recent results using n-hexane produced 95% conversion with 56% benzene; it is speculated that aromatic yield should reach {approximately}70% by further optimization. Pilot- and commercial-scale reactor configurations have been examined; the odds-on-favorite being a shallow fluid-bed of catalyst with incident radiation from the top. Sequencing for maximum cost effectiveness would be day-time endothermic followed by night-time exothermic reactions to produce the products.

  19. Application of the rapid thermal process: Sintering the sputtered aluminum/silicon contact in silicon detector fabrication

    SciTech Connect

    Chen, Wei; Li, Zheng; Kraner, H.W.

    1991-11-01

    Rapid thermal process (RTP) sintering has been used in p{sup +}{minus}n junction detector fabrication. For the same thickness of aluminum film and at the same RTP sintering condition, the leakage current of the p{sup +}{minus}n junction detector with sputtered Al gate showed at least a 50% improvement and no spiking phenomena were observed. RTP sintering in 4% H{sub 2}/N{sub 2} ambient passivates the defects introduced by sputtering and the damage caused by the {sup 60}Co irradiation.

  20. Complete characterization by Raman spectroscopy of the structural properties of thin hydrogenated diamond-like carbon films exposed to rapid thermal annealing

    SciTech Connect

    Rose, Franck Wang, Na; Smith, Robert; Xiao, Qi-Fan; Dai, Qing; Marchon, Bruno; Inaba, Hiroshi; Matsumura, Toru; Saito, Yoko; Matsumoto, Hiroyuki; Mangolini, Filippo; Carpick, Robert W.

    2014-09-28

    We have demonstrated that multi-wavelength Raman and photoluminescence spectroscopies are sufficient to completely characterize the structural properties of ultra-thin hydrogenated diamond-like carbon (DLC:H) films subjected to rapid thermal annealing (RTA, 1 s up to 659 °C) and to resolve the structural differences between films grown by plasma-enhanced chemical vapor deposition, facing target sputtering and filtered cathodic vacuum arc with minute variations in values of mass density, hydrogen content, and sp³ fraction. In order to distinguish unequivocally between films prepared with different density, thickness, and RTA treatment, a new method for analysis of Raman spectra was invented. This newly developed analysis method consisted of plotting the position of the Raman G band of carbon versus its full width at half maximum. Moreover, we studied the passivation of non-radiative recombination centers during RTA by performing measurements of the increase in photoluminescence in conjunction with the analysis of DLC:H networks simulated by molecular dynamics. The results show that dangling bond passivation is primarily a consequence of thermally-induced sp² clustering rather than hydrogen diffusion in the film.

  1. Broad target chemical screening approach used as tool for rapid assessment of groundwater quality.

    PubMed

    ter Laak, Thomas L; Puijker, Leo M; van Leerdam, Jan A; Raat, Klaasjan J; Kolkman, Annemieke; de Voogt, Pim; van Wezel, Annemarie P

    2012-06-15

    The chemical water quality is often assessed by screening for a limited set of target chemicals. This 'conventional' target analysis approach inevitably misses chemicals present in the samples. In this study a 'broad' target screening approach for water quality assessment using high resolution and accurate mass spectrometry (HR MS) was applied to detect a wide variety of organic chemicals in 42 groundwater samples. In this approach, both known and unidentified chemicals observed in previous samples define the training set for the analysis of future samples and, additionally, new samples can be used to extend the training set. Nearly 400 chemicals were observed in the samples, of which 82 were known and more than 313 are of unknown identity. The obtained results were interpreted in relation to the source characteristics and land use. Groundwater that was affected by landfills showed the highest total MS response (ion counts) and most individual chemicals and was therefore considered most contaminated. Furthermore, river bank filtrated water was generally more contaminated than phreatic groundwater and groundwater from (semi)confined aquifers was most pristine. Additionally, industrial chemicals were more frequently observed in river bank filtrated water and pesticides were more frequently observed in water originating from rural areas. The 'broad' target screening approach for both known and unidentified chemicals does provide more information on the over-all water quality than 'conventional' target analysis.

  2. Changes in the color, chemical stability and antioxidant capacity of thermally treated anthocyanin aqueous solution over storage.

    PubMed

    Sui, Xiaonan; Bary, Solène; Zhou, Weibiao

    2016-02-01

    Many anthocyanin-containing foods are thermally processed to ensure their safety, and stored for some time before being consumed. However, the combination of thermal processing and subsequent storage has a significant impact on anthocyanins. This study aimed to investigate the color, chemical stability, and antioxidant capacity of thermally treated anthocyanin aqueous solutions during storage at 4, 25, 45, and 65 °C, respectively. Anthocyanin aqueous solutions were thermally treated before storage. Results showed that the degradation rate of anthocyanins in aqueous solutions was much faster than those in real food. The color of the anthocyanin aqueous solutions changed dramatically during storage. The anthocyanin aqueous solutions stored at 4 °C showed the best chemical stability. Interestingly, the antioxidant capacity of the anthocyanin aqueous solutions stored at lower temperatures remained the same; however, the antioxidant capacity of those thermally treated at 120 or 140 °C and stored at 45 or 65 °C significantly decreased.

  3. A TRPA1 channel that senses thermal stimulus and irritating chemicals in Helicoverpa armigera.

    PubMed

    Wei, J J; Fu, T; Yang, T; Liu, Y; Wang, G R

    2015-08-01

    Sensing and responding to changes in the external environment is important for insect survival. Transient receptor potential (TRP) channels are crucial for various sensory modalities including olfaction, vision, hearing, thermosensation and mechanosensation. Here, we identified and characterized a transient receptor potential gene named as HarmTRPA1 in Helicoverpa armigera antennae. HarmTRPA1 was abundantly expressed in the antennae and labial palps. Transcripts of HarmTRPA1 could also be detected in the head and proboscis. Furthermore, functional analyses of HarmTRPA1 were conducted in the Xenopus Oocyte system. The results showed that the HarmTRPA1 channel could be activated by increasing the temperature from 20 to 45 °C. No significant adaptation was observed when the stimulus was repeated. In addition to thermal stimuli, pungent natural compounds including allyl isothiocyanate, cinnamaldehyde and citronellal also activated HarmTRPA1. Taken together, we infer that HarmTRPA1 may function as both a thermal sensor involved in peripheral temperature detection and as a chemical sensor detecting irritating chemicals in vivo. Our data provide valuable insight into the TRPA1 channel in this moth and lay the foundation for developing novel strategies for pest control. © 2015 The Royal Entomological Society.

  4. Silver-mediated base pairings: towards dynamic DNA nanostructures with enhanced chemical and thermal stability

    NASA Astrophysics Data System (ADS)

    Swasey, Steven M.; Gwinn, Elisabeth G.

    2016-04-01

    The thermal and chemical fragility of DNA nanomaterials assembled by Watson-Crick (WC) pairing constrain the settings in which these materials can be used and how they can be functionalized. Here we investigate use of the silver cation, Ag+, as an agent for more robust, metal-mediated self-assembly, focusing on the simplest duplex building blocks that would be required for more elaborate Ag+-DNA nanostructures. Our studies of Ag+-induced assembly of non-complementary DNA oligomers employ strands of 2-24 bases, with varied base compositions, and use electrospray ionization mass spectrometry to determine product compositions. High yields of duplex products containing narrowly distributed numbers of Ag+ can be achieved by optimizing solution conditions. These Ag+-mediated duplexes are stable to at least 60 mM Mg2+, higher than is necessary for WC nanotechnology schemes such as tile assemblies and DNA origami, indicating that sequential stages of Ag+-mediated and WC-mediated assembly may be feasible. Circular dichroism spectroscopy suggests simple helical structures for Ag+-mediated duplexes with lengths to at least 20 base pairs, and further indicates that the structure of cytosine-rich duplexes is preserved at high urea concentrations. We therefore propose an approach towards dynamic DNA nanomaterials with enhanced thermal and chemical stability through designs that combine sturdy silver-mediated ‘frames’ with WC paired ‘pictures’.

  5. Consolidated conversion of hulled barley into fermentable sugars using chemical, thermal, and enzymatic (CTE) treatment.

    PubMed

    Kim, Tae Hyun; Nghiem, Nhuan P; Taylor, Frank; Hicks, Kevin B

    2011-06-01

    A novel process using chemical, thermal, and enzymatic treatment for conversion of hulled barley into fermentable sugars was developed. The purpose of this process is to convert both lignocellulosic polysaccharides and starch in hulled barley grains into fermentable sugars simultaneously without a need for grinding and hull separation. In this study, hulled barley grains were treated with 0.1 and 1.0 wt.-% sulfuric acid at various temperatures ranging from 110 to 170 °C in a 63-ml flow-through packed-bed stainless steel reactor. After sulfuric acid pretreatment, simultaneous conversion of lignocellulose and starch in the barley grains into fermentable sugars was performed using an enzyme cocktail, which included α-amylase, glucoamylase, cellulase, and β-glucosidase. Both starch and non-starch polysaccharides in the pre-treated barley grains were readily converted to fermentable sugars. The treated hulled barley grains, including their hull, were completely hydrolyzed to fermentable sugars with recovery of almost 100% of the available glucose and xylose. The pretreatment conditions of this chemical, thermal, and enzymatic (CTE) process for achieving maximum yield of fermentable sugars were 1.0 wt.% sulfuric acid and 110 °C. In addition to starch, the acid pretreatment also retained most of the available proteins in solid form, which is essential for subsequent production of fuel ethanol and high protein distiller's dried grains with solubles co-product.

  6. Structure, chemical ordering and thermal stability of Pt-Ni alloy nanoclusters.

    PubMed

    Cheng, Daojian; Yuan, Shuai; Ferrando, Riccardo

    2013-09-04

    Equilibrium structures, chemical ordering and thermal properties of Pt-Ni nanoalloys are investigated by using basin hopping-based global optimization, Monte Carlo (MC) and molecular dynamics (MD) methods, based on the second-moment approximation of the tight-binding potentials (TB-SMA). The TB-SMA potential parameters for Pt-Ni nanoalloys are fitted to reproduce the results of density functional theory calculations for small clusters. The chemical ordering in cuboctahedral (CO) Pt-Ni nanoalloys with 561 and 923 atoms is obtained from the so called semi-grand-canonical ensemble MC simulation at 100 K. Two ordered phases of L12 (PtNi3) and L10 (PtNi) are found for the CO561 and CO923 Pt-Ni nanoalloys, which is in good agreement with the experimental phase diagram of the Pt-Ni bulk alloy. In addition, the order-disorder transition and thermal properties of these nanoalloys are studied by using MC and MD methods, respectively. It is shown that the typical perfect L10 PtNi structure is relatively stable, showing high order-disorder transition temperature and melting point among these CO561 and CO923 Pt-Ni nanoalloys.

  7. Thermal and chemical approaches for oxygen catalytic recombination evaluation on ceramic materials at high temperature

    NASA Astrophysics Data System (ADS)

    Balat, M.; Czerniak, M.; Badie, J. M.

    1997-12-01

    During the atmospheric entry phase, the physico-chemical phenomena taking place on space shuttle walls can lead to an important excess of heating and damage of the protective materials. The aim of this work is the study of the catalytic recombination of atomic oxygen under plasma conditions chosen to simulate the atmospheric reentry. To do that, we have developed an experimental set-up MESOX (Moyen d'Essai Solaire d'OXydation), which associates a solar radiation concentrator and a microwave generator to reach high temperature, low enthalpy flow and low pressure plasma with an air gas flow. The study of atomic oxygen recombination on silicon- or aluminum-based ceramic materials, at high temperature (1000-1800 K) has been done for different pressures (200-2000 Pa) by a thermal and a chemical understanding. The results give a catalycity scale of materials (thermal recombination flux, qrec, and coefficient of atomic oxygen recombination, γ). The catalycity activity is weak for the sintered SiC target with atomic oxygen recombination flux reaching 35 kW/m 2, however, for a target of sintered Al 2O 3, catalytic effect is obtained with energy fluxes between 90 to 180 kW/m 2. The recombination coefficient γ confirms the catalycity scale of these ceramic materials.

  8. Fabricating vertically aligned sub-20 nm Si nanowire arrays by chemical etching and thermal oxidation.

    PubMed

    Li, Luping; Fang, Yin; Xu, Cheng; Zhao, Yang; Zang, Nanzhi; Jiang, Peng; Ziegler, Kirk J

    2016-04-22

    Silicon nanowires (SiNWs) are appealing building blocks in various applications, including photovoltaics, photonics, and sensors. Fabricating SiNW arrays with diameters <100 nm remains challenging through conventional top-down approaches. In this work, chemical etching and thermal oxidation are combined to fabricate vertically aligned, sub-20 nm SiNW arrays. Defect-free SiNWs with diameters between 95 and 200 nm are first fabricated by nanosphere (NS) lithography and chemical etching. The key aspects for defect-free SiNW fabrication are identified as: (1) achieving a high etching selectivity during NS size reduction; (2) retaining the circular NS shape with smooth sidewalls; and (3) using a directional metal deposition technique. SiNWs with identical spacing but variable diameters are demonstrated by changing the reactive ion etching power. The diameter of the SiNWs is reduced by thermal oxidation, where self-limiting oxidation is encountered after oxidizing the SiNWs at 950 °C for 1 h. A second oxidation is performed to achieve vertically aligned, sub-20 nm SiNW arrays. Si/SiO2 core/shell NWs are obtained before removing the oxidized shell. HRTEM imaging shows that the SiNWs have excellent crystallinity.

  9. Multidimensional fully-coupled thermal/chemical/mechanical response of reactive materials

    SciTech Connect

    Hobbs, M.L.; Baer, M.R.

    1995-11-01

    A summary of multidimensional modeling is presented which describes coupled thermals chemical and mechanical response of reactive and nonreactive materials. This modeling addresses cookoff of energetic material (EM) prior to the onset of ignition. Cookoff, lasting from seconds to days, sensitizes the EM whereupon combustion of confined, degraded material determines the level of violence. Such processes are dynamic, occurring over time scales of millisecond to microsecond, and thus more amenable for shock physics analysis. This work provides preignition state estimates such as the amount of decomposition, morphological changes, and quasistatic stress states for subsequent dynamic analysis. To demonstrate a fully-coupled thermal/chemical/quasistatic mechanical capability, several example simulations have been performed: (1) the one-dimensional time-to-explosion experiments, (2) the Naval Air Weapon Center`s (NAWC) small scale cookoff bomb, (3) a small hot cell experiment and (4) a rigid, highly porous, closed-cell polyurethane foam. Predictions compared adequately to available data. Deficiencies in the model and future directions are discussed.

  10. A thermal and chemical degradation approach to decipher pristane and phytane precursors in sedimentary organic matter

    USGS Publications Warehouse

    Koopmans, M.P.; Rijpstra, W.I.C.; Klapwijk, M.M.; De Leeuw, J. W.; Lewan, M.D.; Sinninghe, Damste J.S.

    1999-01-01

    A thermal and chemical degradation approach was followed to determine the precursors of pristane (Pr) and phytane (Ph) in samples from the Gessoso-solfifera, Ghareb and Green River Formations. Hydrous pyrolysis of these samples yields large amounts of Pr and Ph carbon skeletons, indicating that their precursors are predominantly sequestered in high-molecular-weight fractions. However, chemical degradation of the polar fraction and the kerogen of the unheated samples generally does not release large amounts of Pr and Ph. Additional information on the precursors of Pr and Ph is obtained from flash pyrolysis analyses of kerogens and residues after hydrous pyrolysis and after chemical degradation. Multiple precursors for Pr and Ph are recognised in these three samples. The main increase of the Pr/Ph ratio with increasing maturation temperature, which is associated with strongly increasing amounts of Pr and Ph, is probably due to the higher amount of precursors of Pr compared to Ph, and not to the different timing of generation of Pr and Ph.A thermal and chemical degradation approach was followed to determine the precursors of pristane (Pr) and phytane (Ph) in samples from the Gessoso-solfifera, Ghareb and Green River Formations. Hydrous pyrolysis of these samples yields large amounts of Pr and Ph carbon skeletons, indicating that their precursors are predominantly sequestered in high-molecular-weight fractions. However, chemical degradation of the polar fraction and the kerogen of the unheated samples generally does not release large amounts of Pr and Ph. Additional information on the precursors of Pr and Ph is obtained from flash pyrolysis analyses of kerogens and residues after hydrous pyrolysis and after chemical degradation. Multiple precursors for Pr and Ph are recognised in these three samples. The main increase of the Pr/Ph ratio with increasing maturation temperature, which is associated with strongly increasing amounts of Pr and Ph, is probably due to the

  11. Methods for separation/purification utilizing rapidly cycled thermal swing sorption

    DOEpatents

    Tonkovich, Anna Lee Y.; Monzyk, Bruce F.; Wang, Yong; VanderWiel, David P.; Perry, Steven T.; Fitzgerald, Sean P.; Simmons, Wayne W.; McDaniel, Jeffrey S.; Weller, Jr., Albert E.

    2004-11-09

    The present invention provides apparatus and methods for separating fluid components. In preferred embodiments, the apparatus and methods utilize microchannel devices with small distances for heat and mass transfer to achieve rapid cycle times and surprisingly large volumes of fluid components separated in short times using relatively compact hardware.

  12. Chemical and isotopic composition of water from thermal and mineral springs of Washington

    SciTech Connect

    Mariner, R.H.; Presser, T.S.; Evans, W.C.

    1982-02-01

    Waters from the thermal springs of Washington range in chemical composition from dilute Na-HCO/sub 3/ to moderately saline CO/sub 2/-charged Na-HCO/sub 3/-Cl type waters. St. Martin's Hot Spring which discharges a slightly saline Na-Cl water, is the notable exception. The dilute Na-HCO/sub 3/ waters are generally associated with granitic intrusions; the warm to hot CO/sub 2/-charged waters issue on or near the large stratovolcanoes. The dilute waters have oxygen-isotopic compositions that indicate relatively little water-rock exchange. The CO/sub 2/-charged waters are usually more enriched in oxygen-18 due to more extensive water-rock reaction. The carbon-13 in the CO/sub 2/-charged thermal waters is more depleted (-10 to -12 %) than in the cold CO/sub 2/-charged soda springs (-2 to -8%) which are also scattered throughout the Cascades. The hot and cold CO/sub 2/-charged waters are supersaturated with respect to CaCO/sub 3/, but only the hot springs are actively depositing CaCO/sub 3/. Baker, Gamma, Sulphur, and Ohanapecosh hot springs seem to be associated with thermal aquifers of more than 100/sup 0/C. As these springs occur as individual springs or in small clusters, the respective aquifers are probably of restricted size.

  13. In-Plane Thermal Conductivity of Polycrystalline Chemical Vapor Deposition Graphene with Controlled Grain Sizes.

    PubMed

    Lee, Woomin; Kihm, Kenneth David; Kim, Hong Goo; Shin, Seungha; Lee, Changhyuk; Park, Jae Sung; Cheon, Sosan; Kwon, Oh Myoung; Lim, Gyumin; Lee, Woorim

    2017-03-06

    Manipulation of the chemical vapor deposition graphene synthesis conditions, such as operating P, T, heating/cooling time intervals, and precursor gas concentration ratios (CH4/H2), allowed for synthesis of polycrystalline single-layered graphene with controlled grain sizes. The graphene samples were then suspended on 8 μm diameter patterned holes on a silicon-nitride (Si3N4) substrate, and the in-plane thermal conductivities k(T) for 320 K < T < 510 K were measured to be 2660-1230, 1890-1020, and 680-340 W/m·K for average grain sizes of 4.1, 2.2, and 0.5 μm, respectively, using an opto-thermal Raman technique. Fitting of these data by a simple linear chain model of polycrystalline thermal transport determined k = 5500-1980 W/m·K for single-crystal graphene for the same temperature range above; thus, significant reduction of k was achieved when the grain size was decreased from infinite down to 0.5 μm. Furthermore, detailed elaborations were performed to assess the measurement reliability of k by addressing the hole-edge boundary condition, and the air-convection/radiation losses from the graphene surface.

  14. Kinetic and chemical characterization of thermal decomposition of dicumylperoxide in cumene.

    PubMed

    Di Somma, Ilaria; Marotta, Raffaele; Andreozzi, Roberto; Caprio, Vincenzo

    2011-03-15

    Dicumylperoxide (DCP) is one of the most used peroxides in the polymer industry. It has been reported that its thermal decomposition can result in runaway phenomena and thermal explosions with significant economic losses and injuries to people. In the present paper thermal behaviour of dicumylperoxide in cumene was investigated over the temperature range of 393-433 K under aerated and de-aerated conditions. The results indicated that when oxygen was present, the decomposition rate did not follow a simple pseudo-first order kinetic as previously reported in literature. A satisfactory fit of the experimental data was, in this case, achieved by means of kinetic expression derived under the assumption of an autocatalytic scheme of reaction. The reaction rate was, on the contrary, correctly described by a pseudo-first order kinetic in absence of oxygen. Under both aerated and de-aerated conditions, chemical analysis showed that the decomposition mainly resulted in the formation of acetophenone and dimethylphenylcarbinol with minor occurrence of 2,3-dimethyl-2,3-diphenylbutane. The formation of methane and ethane was also invariably observed while the appearance of cumylhydroperoxide as a reaction intermediate was detected under only aerated conditions. Therefore, two reaction schemes were proposed to explain system behaviour in the presence of oxygen and after its purging. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Chemical and isotopic composition of water from thermal springs and mineral springs of Washington

    USGS Publications Warehouse

    Mariner, R.H.; Presser, T.S.; Evans, William C.

    1982-01-01

    Water from thermal springs of Washington range in chemical composition from dilute NaHC03, to moderately saline C02-charged NaHC03-Cl waters. St. Martin 's Hot Spring which discharges a slightly saline NaCl water, is the notable exception. Mineral springs generally discharge a moderately saline C02-charged NaHC03-Cl water. The dilute Na-HC03 waters are generally associated with granite. The warm to hot waters charged with C02 issue on or near the large stratovolcanoes and many of the mineral springs also occur near the large volcanoes. The dilute waters have oxygen isotopic compositions which indicate relatively little water-rock exchange. The C02-charged waters are usually more enriched in oxygen-18 due to more extensive water-rock reaction. Carbon-13 in the C02-charged thermal waters is more depleted (-10 to -12 permil) than in the cold C02-charged soda springs (-2 to -8 permil) which are also scattered throughout the Cascades. The hot and cold C02-charged waters are supersaturated with respect to CaC03, but only the hot springs are actively depositing CaC03. Baker, Gamma, Sulphur , and Ohanapecosh seem to be associated with thermal aquifers of more than 100C. (USGS)

  16. Characterization of solid bitumens originating from thermal chemical alteration and thermochemical sulfate reduction

    NASA Astrophysics Data System (ADS)

    Kelemen, Simon R.; Walters, Clifford C.; Kwiatek, Peter J.; Freund, Howard; Afeworki, Mobae; Sansone, Michael; Lamberti, William A.; Pottorf, Robert J.; Machel, Hans G.; Peters, Kenneth E.; Bolin, Trudy

    2010-09-01

    Solid bitumen can arise from several reservoir processes acting on migrated petroleum. Insoluble solid organic residues can form by oxidative processes associated with thermochemical sulfate reduction (TSR) as well as by thermal chemical alteration (TCA) of petroleum. TCA may follow non-thermal processes, such as biodegradation and asphaltene precipitation, that produce viscous fluids enriched in polar compounds that are then altered into solid bitumens. It is difficult to distinguish solid bitumen formed by TCA from TSR since both processes occur under relatively high temperatures. The focus of the present work is to characterize solid bitumen samples associated with TSR- or TCA-processes using a combination of solid-state X-ray Photoelectron Spectroscopy (XPS), Sulfur X-ray Absorption Near Edge Structure Spectroscopy (S-XANES), and 13C NMR. Naturally occurring solid bitumens from three locations, Nisku Formation, Brazeau River area (TSR-related); La Barge Field, Madison Formation (TSR-related); and, the Alaskan North Slope, Brooks Range (TCA-related), are compared to solid bitumens generated in laboratory simulations of TSR and TCA. The chemical nature of solid bitumens with respect to organic nitrogen and sulfur can be understood in terms of (1) the nature of hydrocarbon precursor molecules, (2) the mode of sulfur incorporation, and (3) their concentration during thermal stress. TSR-solid bitumen is highly aromatic, sulfur-rich, and nitrogen-poor. These heteroatom distributions are attributed to the ability of TSR to incorporate copious amounts of inorganic sulfur (S/C atomic ratio >0.035) into aromatic structures and to initial low levels of nitrogen in the unaltered petroleum. In contrast, TCA-solid bitumen is derived from polar materials that are initially rich in sulfur and nitrogen. Aromaticity and nitrogen increase as thermal stress cleaves aliphatic moieties and condensation reactions take place. TCA-bitumens from the Brooks Range have <75% aromatic

  17. Determination of metformin in mouse, rat, dog and human plasma samples by laser diode thermal desorption/atmospheric pressure chemical ionization tandem mass spectrometry.

    PubMed

    Swales, John G; Gallagher, Richard; Peter, Raimund M

    2010-11-02

    A simple, rapid and robust high-throughput assay for the quantitative analysis of metformin in plasma from different species using laser diode thermal desorption interfaced with atmospheric chemical pressure ionization tandem mass spectrometry (LDTD-APCI-MSMS) was developed for use in a pharmaceutical discovery environment. In order to minimize sample preparation a generic protein precipitation method was used to extract metformin from the plasma. Laser diode thermal desorption is a relatively new sample introduction method, the optimization of the instrumental parameters are presented. The method was successfully applied to spiked mouse, rat, dog and human plasma samples and was subsequently used to determine the oral pharmacokinetics of metformin after dosing to male rats in order to support drug discovery projects. The deviations for intra-assay accuracy and precision across the four species were less than 30% at all calibration and quality control levels.

  18. Influence of sprite streamers in the mesospheric chemical and thermal balance

    NASA Astrophysics Data System (ADS)

    Parra-Rojas, Francisco C.; Luque, Alejandro; Gordillo-Vázquez, Francisco J.

    2015-04-01

    We present new results to contribute to the fundamental understanding of the chemistry of non-equilibrium plasmas produced by nighttime sprite streamers in the mesosphere and their influence on the chemical composition and thermal evolution of the upper atmosphere. This contribution describes the kinetic model used and the time evolution of the concentration of many important species for the sprite and its afterglow through an upgrade of previous TLE kinetic models [1], [2]. A one-dimensional self-consistent model has been developed to study the chemical and thermal effects of a single sprite streamer in the Earth mesosphere. We have used sprite streamer profiles with three different driving current durations (5 ms, 50 ms and 100 ms) between 50 and 80 km of altitude and considering a kinetic scheme of air with 20 chemical species. Our model predicts strong increases in practically all the concentrations of the species studied at the moment of the streamer head passage. Moreover, their densities remain high during the streamer afterglow phase. The electron concentration can reach values of up to 108 cm-3 in the three cases analyzed. The model also predicts an important enhancement, of several orders of magnitude above ambient values, of nitrogen oxides (NOx and N2O) and the considered metastables species (N2(A), O2(a), O2(b)). Metastables are capable of storing energy for relatively long time (hundreds of seconds). On the other hand, we found that the 4.26 μm IR emission brightness of CO2 can exceed in 4 orders of magnitude the threshold of visibility (1 MR) at low altitudes (< 65 km) for the cases of intermediate (50 ms) and long (100 ms) driving currents. These results suggest the possibility of detecting sprite IR emissions from space with the appropriate instrumentation. Moreover, according to our model, the Meinel emission brightness of N2+ could also reach the threshold of visibility below 50 km. Finally, we found that the thermal impact of sprites in the

  19. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence

    PubMed Central

    Flynn, Padrig B.; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P.; Elliott, Christopher T.; Laverty, Garry; Gorman, Sean P.; Graham, William G.; Gilmore, Brendan F.

    2016-01-01

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30–60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa. PMID:27242335

  20. Non-thermal Plasma Exposure Rapidly Attenuates Bacterial AHL-Dependent Quorum Sensing and Virulence.

    PubMed

    Flynn, Padrig B; Busetti, Alessandro; Wielogorska, Ewa; Chevallier, Olivier P; Elliott, Christopher T; Laverty, Garry; Gorman, Sean P; Graham, William G; Gilmore, Brendan F

    2016-05-31

    The antimicrobial activity of atmospheric pressure non-thermal plasma has been exhaustively characterised, however elucidation of the interactions between biomolecules produced and utilised by bacteria and short plasma exposures are required for optimisation and clinical translation of cold plasma technology. This study characterizes the effects of non-thermal plasma exposure on acyl homoserine lactone (AHL)-dependent quorum sensing (QS). Plasma exposure of AHLs reduced the ability of such molecules to elicit a QS response in bacterial reporter strains in a dose-dependent manner. Short exposures (30-60 s) produce of a series of secondary compounds capable of eliciting a QS response, followed by the complete loss of AHL-dependent signalling following longer exposures. UPLC-MS analysis confirmed the time-dependent degradation of AHL molecules and their conversion into a series of by-products. FT-IR analysis of plasma-exposed AHLs highlighted the appearance of an OH group. In vivo assessment of the exposure of AHLs to plasma was examined using a standard in vivo model. Lettuce leaves injected with the rhlI/lasI mutant PAO-MW1 alongside plasma treated N-butyryl-homoserine lactone and n-(3-oxo-dodecanoyl)-homoserine lactone, exhibited marked attenuation of virulence. This study highlights the capacity of atmospheric pressure non-thermal plasma to modify and degrade AHL autoinducers thereby attenuating QS-dependent virulence in P. aeruginosa.

  1. A HYBRID THERMAL VIDEO AND FTTR SPECTROMETER FOR RAPIDLY LOCATING AND CHARACTERIZING GAS LEAKS

    EPA Science Inventory

    Undiscovered gas leaks, known as fugitive emissions, in chemical plants and refinery operations can impact regional air quality as well as being a public health problem. Surveying a facility for potential gas leaks can be a daunting task. An efficient, accurate and cost-effecti...

  2. A HYBRID THERMAL VIDEO AND FTTR SPECTROMETER FOR RAPIDLY LOCATING AND CHARACTERIZING GAS LEAKS

    EPA Science Inventory

    Undiscovered gas leaks, known as fugitive emissions, in chemical plants and refinery operations can impact regional air quality as well as being a public health problem. Surveying a facility for potential gas leaks can be a daunting task. An efficient, accurate and cost-effecti...

  3. Boron activation and diffusion in silicon and strained silicon-on-insulator by rapid thermal and flash lamp annealings

    NASA Astrophysics Data System (ADS)

    Lanzerath, F.; Buca, D.; Trinkaus, H.; Goryll, M.; Mantl, S.; Knoch, J.; Breuer, U.; Skorupa, W.; Ghyselen, B.

    2008-08-01

    We present experimental results on the activation and diffusion behaviors of boron in silicon-on-insulator and strained silicon-on-insulator using standard rapid thermal processing treatments as well as flash lamp annealing. After boron implantation at different doses and at a low energy of 1 keV, samples were annealed to activate the dopants, and secondary ion mass spectrometry and Hall measurements were carried out to determine boron diffusion and the amount of activated dopants, respectively. In contrast to rapid thermal annealing, flash lamp annealing enables the activation without significant diffusion of dopants. In addition, we investigated the effect of coating the samples with antireflection layers to increase the absorbed energy during flash annealing. As a result, the activation was increased significantly to values comparable with the activation obtained with standard annealing. Furthermore, the relation between the observed boron diffusion and activation as a function of the implantation and annealing parameters is discussed in terms of the kinetics of the defects involved in these processes.

  4. Influence of rapid thermal annealing on a 30 stack InAs/GaAs quantum dot infrared photodetector

    NASA Astrophysics Data System (ADS)

    Stewart, K.; Buda, M.; Wong-Leung, J.; Fu, L.; Jagadish, C.; Stiff-Roberts, A.; Bhattacharya, P.

    2003-10-01

    In this article the effect of rapid thermal annealing (RTA) on a 30 stacked InAs/GaAs, molecular beam epitaxially grown quantum dot infrared photodetector (QDIP) device is studied. Temperatures in the range of 600-800 °C for 60 s, typical of atomic interdiffusion methods are used. After rapid thermal annealing the devices exhibited large dark currents and no photoresponse could be measured. Double crystal x-ray diffraction and cross sectional transmission electron microscopy studies indicate that this could be the result of strain relaxation. V-shaped dislocations which extended across many quantum dot (QD) layers formed in the RTA samples. Smaller defect centers were observed throughout the as-grown sample and are also likely a strain relaxation mechanism. This supports the idea that strained structures containing dislocations are more likely to relax via the formation of dislocations and/or the propagation of existing dislocations, instead of creating atomic interdiffusion during RTA. Photoluminescence (PL) studies also found that Si related complexes developed in the Si doped GaAs contact layers with RTA. The PL from these Si related complexes overlaps and dominates the PL from our QD ground state.

  5. Pt/Ti ohmic contacts to ultrahigh carbon-doped p-GaAs formed by rapid thermal processing

    NASA Astrophysics Data System (ADS)

    Katz, A.; Abernathy, C. R.; Pearton, S. J.

    1990-03-01

    Increasing the concentration of the carbon dopants in p-GaAs layers grown on semi-insulating substrates to levels of 1×1020 to 5×1020 cm-3 enables the formation of an ohmic contact with low resistance using the refractory Pt/Ti metallization. These contacts showed ohmic behavior prior to any heat treatment with specific contact resistance as low as 7×10-6 Ω cm2 (0.08 Ω mm) for the lower doping level and 8×10-7 Ω cm2 (0.04 Ω mm) for the higher level. Small improvements in the specific resistance of the former contact were achieved by rapid thermal processing at a temperature of 450 °C for 30 s, which yielded a value of 4.9×10-6 Ω cm2. The electrical nature of the contact to the heavily doped GaAs was not affected by heat treatments at temperatures up to 450 °C. Rapid thermal processing of these contacts at higher temperatures, however, caused an increase in the contact resistance which was correlated to the expanded Ti/GaAs and Pt/GaAs interfacial reactions. Current-voltage characteristics were found to be temperature independent. This suggested that the field emission quantum-mechanical tunneling was the dominant carrier transport mechanism in these contacts.

  6. Rapid thermal anneal in InP, GaAs and GaAs/GaAlAs

    NASA Astrophysics Data System (ADS)

    Descouts, B.; Duhamel, N.; Godefroy, S.; Krauz, P.

    Ion implantation in semiconductors provides a doping technique with several advantages over more conventional doping methods and is now extensively used for device applications, e.g. field effect transistors (MESFET GaAs, MIS (InP), GaAs/GaAlAs heterojunction bipolar transistors (HBT). Because of the lattice disorder produced by the implantation, the dopant must be made electrically active by a postimplant anneal. As the device performances are very dependent on its electrical characteristics, the anneal is a very important stage of the process. Rapid anneal is known to provide less exodiffusion and less induffusion of impurities compared to conventional furnace anneal, so this technique has been used in this work to activate an n-type dopant (Si) in InP and a p-type dopant (Mg) in GaAs and GaAs/GaAIAs. These two ions have been chosen to realize implanted MIS InP and the base contacts for GaAs/GaAlAs HBTs. The experimental conditions to obtain the maximum electrical activity in these two cases will be detailed. For example, although we have not been able to obtain a flat profile in Mg + implanted GaAs/GaAlAs heterostructure by conventional thermal anneal, rapid thermal anneal gives a flat hole profile over a depth of 0.5 μm with a concentration of 1 x 10 19 cm -3.

  7. An endoscopic method for thermal and chemical stimulation of the human oesophagus.

    PubMed

    Olesen, S S; Olesen, A E; Gravesen, F; Poulsen, J L; Funch-Jensen, P; Gregersen, H; Drewes, A M

    2009-12-01

    Previous methods for visceral thermal stimulation have lacked control of the temperature rate and visual inspection of the organ. The aims of this study was to develop a method for linear control of heat stimulation in the human oesophagus combined with endoscopy, to assess the reproducibility of this method and to investigate sensitivity to thermal stimulation of the distal oesophagus before and after acid perfusion. A probe with a 2.8 mm endoscope inside was constructed permitting heat and chemical stimulation. Three different temperature ramps were applied in the distal oesophagus in 12 healthy subjects by recirculation of heated water in a bag. Endoscopy of the oesophageal mucosa was performed prior to experimental stimulation. The temperature, the time of stimulation and the area under the temperature curve (AUC) were measured at the pain detection threshold. Thermal stimulation was repeated after perfusion of the oesophagus with acid. The method was tested on two subsequent days to assess reproducibility. All subjects had a normal endoscopic examination. Day-to-day reproducibility was good for the three temperature ramps (intra-class correlations >0.6). The subjects tolerated less heat stimulation, a decrease in AUC (P = 0.0003), a decrease in time to pain detection threshold (P = 0.005) and decreased temperature at pain detection threshold (P = 0.0001) after acid perfusion. The slow ramp was the most sensitive, showing a decrease in AUC of 29%. The present method was easily implemented and showed good reproducibility. It can potentially be used in basic experiments, drug and clinical studies as it provides a controllable thermal stimulus.

  8. A battery-powered notebook thermal cycler for rapid multiplex real-time PCR analysis.

    PubMed

    Belgrader, P; Young, S; Yuan, B; Primeau, M; Christel, L A; Pourahmadi, F; Northrup, M A

    2001-01-15

    A compact, real-time PCR instrument was developed for rapid, multiplex analysis of nucleic acids in an inexpensive, portable format. The instrument consists of a notebook computer, two reaction modules with integrated optics for four-color fluorescence detection, batteries, and a battery-charging system. The instrument weighs 3.3 kg, measures 26 x 22 x 7.5 cm, and can run continuously on the internal batteries for 4 h. Independent control of the modules allows differing temperature profiles and detection schemes to be run simultaneously. Results are presented that demonstrate rapid (1) detection and identification of Bacillus subtilis and Bacillus thuringensis spores and (2) characterization of a single nucleotide polymorphism for the hereditary hemochromatosis gene.

  9. Rapid Hydrogen Peroxide release from the coral Stylophora pistillata during feeding and in response to chemical and physical stimuli

    PubMed Central

    Armoza-Zvuloni, Rachel; Schneider, Avi; Sher, Daniel; Shaked, Yeala

    2016-01-01

    Corals make use of different chemical compounds during interactions with prey, predators and aggressors. Hydrogen Peroxide (H2O2) is produced and released by a wide range of organisms as part of their defense against grazers or pathogens. In coral reefs, the large fluxes and relatively long half-life of H2O2, make it a potentially important info-chemical or defense molecule. Here we describe a previously unstudied phenomenon of rapid H2O2 release from the reef-building coral Stylophora pistillata during feeding on zooplankton and in response to chemical and physical stimuli. Following stimuli, both symbiotic and bleached corals were found to rapidly release H2O2 to the surrounding water for a short period of time (few minutes). The H2O2 release was restricted to the site of stimulus, and an increase in physical stress and chemical stimuli concentration resulted in elevated H2O2 release. Omission of calcium (a key regulator of exocytotic processes) from the experimental medium inhibited H2O2 release. Hence we suggest that H2O2 is actively released in response to stimuli, rather than leaking passively from the coral tissue. We estimate that at the site of stimulus H2O2 can reach concentrations potentially high enough to deter predators or motile, potentially pathogenic, bacteria. PMID:26875833

  10. Direct chemical oxidation: a non-thermal technology for the destruction of organic wastes

    SciTech Connect

    Balazs, G.B.; Cooper, J. F.; Lewis, P. R.; Adamson, M. G.

    1998-02-01

    Direct Chemical Oxidation (DCO) is a non-thermal, ambient pressure, aqueous-based technology for the oxidative destruction of the organic components of hazardous or mixed waste streams. The process has been developed for applications in waste treatment and chemical demilitarization and decontamination at LLNL since 1992, and is applicable to the destruction of virtually all solid or liquid organics, including: chlorosolvents, oils and greases, detergents, organic-contaminated soils or sludges, explosives, chemical and biological warfare agents, and PCB's. [1-15] The process normally operates at 80-100 C, a heating requirement which increases the difficulty of surface decontamination of large objects or, for example, treatment of a wide area contaminated soil site. The driver for DCO work in FY98 was thus to investigate the use of catalysts to demonstrate the effectiveness of the technology for organics destruction at temperatures closer to ambient. In addition, DCO is at a sufficiently mature stage of development that technology transfer to a commercial entity was a logical next step, and was thus included in FY98 tasks.

  11. Luffa cylindrica sponges as a thermally and chemically stable support for Aspergillus niger lipase.

    PubMed

    Zdarta, Jakub; Jesionowski, Teofil

    2016-05-01

    The use of biopolymer compounds as matrices for enzyme immobilization is currently a focus of increasing interest. In the present work we propose the use of Luffa cylindrica vegetable sponges as a support for the lipase extracted from Aspergillus niger. Effectiveness of immobilization was analyzed using Fourier transform infrared spectroscopy, elemental analysis and the Bradford method. An initial enzyme solution concentration of 1.0 mg/mL and an immobilization time of 12 h were selected as the parameters that produce a system retaining the highest hydrolytic activity (84% of free enzyme). The resulting biocatalyst system also exhibited high thermal and chemical stability, reusability and storage stability, which makes it a candidate for use in a wide range of applications. Kinetic parameters for the native and immobilized lipase were also calculated. The value of the Michaelis-Menten constant for the immobilized lipase (0.47 mM) is higher than for the free enzyme (0.21 mM), which indicates that the adsorbed enzyme exhibits a lower affinity to the substrate than native lipase. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:657-665, 2016. © 2016 American Institute of Chemical Engineers.

  12. Development of Chemically and Thermally Robust Lithium Fast Ion Conducting Chalcogenide Glasses

    NASA Technical Reports Server (NTRS)

    Martin, Steve W.; Hagedorn, Norman (Technical Monitor)

    2002-01-01

    In this project, a new research thrust into the development of an entirely new class of FIC glasses has begun that may lead to a new set of optimized thin-film lithium ion conducting materials. New chemically robust FIC glasses are being prepared that are expected to exhibit unusually high chemical and electrochemical stability. New thermally robust FIC glasses are being prepared that exhibit softening points in excess of 500 C which will dramatically expand the usable operating temperature range of batteries, fuel-cells, and sensors using such electrolytes. Glasses are being explored in the general compositional series xLi2S+ yGa2S3 + (1-x-y)GeS2. Li2S is added as the source of the conductive lithium ions. GeS2 is the base glass-forming phase and the trivalent sulfides, Ga2S3, is added to increase the "refractoniness" of the glass, that is to significantly increase the softening point of the glass as well as its chemical stability. By optimizing the composition of the glass, new glasses and glass-ceramic FIC materials have been prepared with softening points in excess of 500 C and conductivities above 10(exp -3)/Ohm cm at room temperature. These latter attributes are currently not available in any FIC glasses to date.

  13. GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

    SciTech Connect

    Smith, JN

    2016-04-01

    The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

  14. Formation of thermal flow fields and chemical transport in air and water by atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Shimizu, Tetsuji; Iwafuchi, Yutaka; Morfill, Gregor E.; Sato, Takehiko

    2011-05-01

    Cold atmospheric plasma is a potential tool for medical purposes, e.g. disinfection/sterilization. In order for it to be effective and functional, it is crucial to understand the transport mechanism of chemically reactive species in air as well as in liquid. An atmospheric plasma discharge was produced between a platinum pin electrode and the surface of water. The thermal flow field of a cold atmospheric plasma as well as its chemical components was measured. A gas flow with a velocity of around 15 m s-1 to the water's surface was shown to be induced by the discharge. This air flow induced a circulating flow in the water from the discharge point at the water's surface because of friction. It was also demonstrated that the chemical components generated in air dissolved in water and the properties of the water changed. The reactive species were believed to be distributed mainly by convective transport in water, because the variation in the pH profile indicated by a methyl red solution resembled the induced flow pattern.

  15. Drying of Indian subcontinent by rapid Indian Ocean warming and a weakening land-sea thermal gradient.

    PubMed

    Roxy, Mathew Koll; Ritika, Kapoor; Terray, Pascal; Murtugudde, Raghu; Ashok, Karumuri; Goswami, B N

    2015-06-16

    There are large uncertainties looming over the status and fate of the South Asian summer monsoon, with several studies debating whether the monsoon is weakening or strengthening in a changing climate. Our analysis using multiple observed datasets demonstrates a significant weakening trend in summer rainfall during 1901-2012 over the central-east and northern regions of India, along the Ganges-Brahmaputra-Meghna basins and the Himalayan foothills, where agriculture is still largely rain-fed. Earlier studies have suggested an increase in moisture availability and land-sea thermal gradient in the tropics due to anthropogenic warming, favouring an increase in tropical rainfall. Here we show that the land-sea thermal gradient over South Asia has been decreasing, due to rapid warming in the Indian Ocean and a relatively subdued warming over the subcontinent. Using long-term observations and coupled model experiments, we provide compelling evidence that the enhanced Indian Ocean warming potentially weakens the land-sea thermal contrast, dampens the summer monsoon Hadley circulation, and thereby reduces the rainfall over parts of South Asia.

  16. Rapid formulation assessment of filgrastim therapeutics by a thermal stress test.

    PubMed

    Alebouyeh, Mahmoud; Tahzibi, Abbas; Yaghoobzadeh, Sareh; Zahedy, Elnaz Tamaskany; Kiumarsi, Shiva; Soltanabad, Mojtaba Hadi; Shahbazi, Saleh; Amini, Hossein

    2016-05-01

    The biosimilar versions of recombinant methionyl human granulocyte colony-stimulating factor (rh-Met-G-CSF, filgrastim) are now widely available. Because changes to the formulation often lead to subtle differences, there is a critical need to define techniques to test and insure the quality of these products. The present study was designed to compare formulation and thermal stress stability of filgrastim products. The formulation ingredients including acetate, polysorbate 80, and sorbitol were determined using state-of-the-art validated analytical methods. The formulation pH and osmolality were also measured. Moreover, the stability profiles of 8 filgrastim products using thermal stress at 57 °C for 4 h were assessed by size-exclusion high-performance liquid chromatography (SE-HPLC) and in vitro biological assay. The products had different stability profiles. More stable products were within the specification for formulation and less stable products were beyond the specification limits. Altogether, the results suggest that a short-time stress study at 57 °C and analysis of filgrastim by SE-HPLC could unveil formulation problems and is potentially useful for comparability studies. Copyright © 2016 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

  17. Methane from partially digested sewage sludge using a steam-injection rapid thermal reactor. Final report

    SciTech Connect

    Leuschner, A.P.; Laquidara, M.J.

    1988-09-01

    Each day, a fleet of barges hauls 300,000 cubic feet of sewage sludge from wastewater treatment facilities in New York City, to an ocean dumping site 106 miles offshore. On January 1, 1992, this ocean dumping site will be officially closed by federal mandate, forcing the city to find alternative disposal methods for its sewage sludge. Researchers at Dynatech and the Thayer School of Engineering at Dartmouth College have explored an innovative method for enhancing the anaerobic digestion sludge treatment system. Results from an extensive series of laboratory tests indicate that using a thermal reactor, an additional 70% of the organic material in the sludge can be converted to biogas by anaerobic digestion. More importantly, 85% of the total organic material is removed from the sludge. The remaining sludge was dewatered and found to be two to four times drier than normally dewatered sludge. Applying these results to NYC, the volume of sludge requiring disposal might be reduced from 300,000 cubic feet per day to about 13,000 cubic feet per day through a three-step process employing thermal reactors, anaerobic digestion and dewatering.

  18. Characterization and Modeling of a Coupled Thermal-Hydrological-Mechanical-Chemical-Biological Experimental Facility at DUSEL

    NASA Astrophysics Data System (ADS)

    Sonnenthal, E. L.; Elsworth, D.; Lowell, R. P.; Maher, K.; Mailloux, B. J.; Uzunlar, N.; Conrad, M. E.; Jones, T. L.; Olsen, N. J.

    2010-12-01

    A design is being formulated for a large-scale subsurface experimental facility at the 4850 foot level of the Homestake Mine in South Dakota. The purpose of the experiment is to investigate coupled Thermal-Hydrological-Mechanical-Chemical-Biological (THMCB) processes in fractured rock under stress and would be part of the proposed Deep Underground Science and Engineering Laboratory (DUSEL). Key questions we propose to answer are: 1) What are the effective reaction rates for mineral-fluid interaction in fractured rock under stress?; 2) How does mineral and fluid chemistry affect fracture mechanical behavior and permeability changes under stress at elevated temperatures?; and 3) How do microbial communities evolve in fractured rock under a thermal gradient and under changing stress conditions? In addition to the experiment as an in-situ laboratory for studying crustal processes, it has significant benefits for evaluating stimulation and production in Enhanced Geothermal Systems. Design and planning of the experiment included characterization of the geological, chemical, and isotopic characteristics of the rock and seeping fluids, thermal-hydrological and reactive transport modeling. During a reconnaissance study, strong heterogeneity in fracture fluxes and permeability were observed at the block site with some open boreholes continuously flowing at up to 1 liter/minute, and locally elevated fluid temperatures. A two-dimensional thermal-hydrological model was developed to evaluate fluid fluxes and temperatures as a function of heat input and borehole heater configuration. The dual permeability model considers fluid flow and heat transfer between an array of fractures and rock matrix, both having permeability anisotropy. A horizontal rock matrix permeability of 10-18 m2 was based on recent lab measurements, with a vertical matrix permeability estimated to be one order-of-magnitude higher to account for the strong nearly vertical foliation in the Homestake and Poorman

  19. Synthesis Gas Production by Rapid Solar Thermal Gasification of Corn Stover

    SciTech Connect

    Perkins, C. M.; Woodruff, B.; Andrews, L.; Lichty, P.; Lancaster, B.; Weimer, A. W.; Bingham, C.

    2008-03-01

    Biomass resources hold great promise as renewable fuel sources for the future, and there exists great interest in thermochemical methods of converting these resources into useful fuels. The novel approach taken by the authors uses concentrated solar energy to efficiently achieve temperatures where conversion and selectivity of gasification are high. Use of solar energy removes the need for a combustion fuel and upgrades the heating value of the biomass products. The syngas product of the gasification can be transformed into a variety of fuels useable with today?s infrastructure. Gasification in an aerosol reactor allows for rapid kinetics, allowing efficient utilization of the incident solar radiation and high solar efficiency.

  20. Thermal ecology on an exposed algal reef: infrared imagery a rapid tool to survey temperature at local spatial scales

    NASA Astrophysics Data System (ADS)

    Cox, T. E.; Smith, C. M.

    2011-12-01

    We tested the feasibility of infra-red (IR) thermography as a tool to survey in situ temperatures in intertidal habitats. We employed this method to describe aspects of thermal ecology for an exposed algal reef in the tropics (O`ahu, Hawai`i). In addition, we compared temperatures of the surrounding habitat as determined by IR thermography and traditional waterproof loggers. Images of reef organisms (6 macroalgae, 9 molluscs, 1 anthozoan, and 2 echinoderms), loggers, and landscapes were taken during two diurnal low tides. Analysis of IR thermographs revealed remarkable thermal complexity on a narrow tropical shore, as habitats ranged from 18.1 to 38.3°C and surfaces of organisms that ranged from 21.1 to 33.2°C. The near 20°C difference between abiotic habitats and the mosaic of temperatures experienced by reef organisms across the shore are similar to findings from temperate studies using specialized longterm loggers. Further, IR thermography captured rapid temperature fluctuations that were related to tidal height and cross-correlated to wave action. Finally, we gathered evidence that tidal species were associated with particular temperature ranges and that two species possess morphological characteristics that limit thermal stress. Loggers provided similar results as thermography but lack the ability to resolve variation in fine-scale spatial and temporal patterns. Our results support the utility of IR thermography in exploring thermal ecology, and demonstrate the steps needed to calibrate data leading to establishment of baseline conditions in a changing and heterogeneous environment.