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Sample records for absorbent glass mat

  1. Micro-hybrid electric vehicle application of valve-regulated lead-acid batteries in absorbent glass mat technology: Testing a partial-state-of-charge operation strategy

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Stoermer, A. O.; Hockgeiger, E.

    The BMW Group has launched two micro-hybrid functions in high volume models in order to contribute to reduction of fuel consumption in modern passenger cars. Both the brake energy regeneration (BER) and the auto-start-stop function (ASSF) are based on the conventional 14 V vehicle electrical system and current series components with only little modifications. An intelligent control algorithm of the alternator enables recuperative charging in braking and coasting phases, known as BER. By switching off the internal combustion engine at a vehicle standstill the idling fuel consumption is effectively reduced by ASSF. By reason of economy and package a lead-acid battery is used as electrochemical energy storage device. The BMW Group assembles valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology in the micro-hybrid electrical power system since special challenges arise for the batteries. By field data analysis a lower average state-of-charge (SOC) due to partial state-of-charge (PSOC) operation and a higher cycling rate due to BER and ASSF are confirmed in this article. Similar to a design of experiment (DOE) like method we present a long-term lab investigation. Two types of 90 Ah VRLA AGM batteries are operated with a test bench profile that simulates the micro-hybrid vehicle electrical system under varying conditions. The main attention of this lab testing is focused on capacity loss and charge acceptance over cycle life. These effects are put into context with periodically refresh charging the batteries in order to prevent accelerated battery aging due to hard sulfation. We demonstrate the positive effect of refresh chargings concerning preservation of battery charge acceptance. Furthermore, we observe moderate capacity loss over 90 full cycles both at 25 °C and at 3 °C battery temperature.

  2. Nonwoven glass fiber mat reinforces polyurethane adhesive

    NASA Technical Reports Server (NTRS)

    Roseland, L. M.

    1967-01-01

    Nonwoven glass fiber mat reinforces the adhesive properties of a polyurethane adhesive that fastens hardware to exterior surfaces of aluminum tanks. The mat is embedded in the uncured adhesive. It ensures good control of the bond line and increases the peel strength.

  3. A field operational test on valve-regulated lead-acid absorbent-glass-mat batteries in micro-hybrid electric vehicles. Part II. Results based on multiple regression analysis and tear-down analysis

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Karspeck, T.; Ott, C.; Weirather-Koestner, D.; Stoermer, A. O.

    2011-03-01

    In the first part of this work [1] a field operational test (FOT) on micro-HEVs (hybrid electric vehicles) and conventional vehicles was introduced. Valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology and flooded batteries were applied. The FOT data were analyzed by kernel density estimation. In this publication multiple regression analysis is applied to the same data. Square regression models without interdependencies are used. Hereby, capacity loss serves as dependent parameter and several battery-related and vehicle-related parameters as independent variables. Battery temperature is found to be the most critical parameter. It is proven that flooded batteries operated in the conventional power system (CPS) degrade faster than VRLA-AGM batteries in the micro-hybrid power system (MHPS). A smaller number of FOT batteries were applied in a vehicle-assigned test design where the test battery is repeatedly mounted in a unique test vehicle. Thus, vehicle category and specific driving profiles can be taken into account in multiple regression. Both parameters have only secondary influence on battery degradation, instead, extended vehicle rest time linked to low mileage performance is more serious. A tear-down analysis was accomplished for selected VRLA-AGM batteries operated in the MHPS. Clear indications are found that pSoC-operation with periodically fully charging the battery (refresh charging) does not result in sulphation of the negative electrode. Instead, the batteries show corrosion of the positive grids and weak adhesion of the positive active mass.

  4. A field operational test on valve-regulated lead-acid absorbent-glass-mat batteries in micro-hybrid electric vehicles. Part I. Results based on kernel density estimation

    NASA Astrophysics Data System (ADS)

    Schaeck, S.; Karspeck, T.; Ott, C.; Weckler, M.; Stoermer, A. O.

    2011-03-01

    In March 2007 the BMW Group has launched the micro-hybrid functions brake energy regeneration (BER) and automatic start and stop function (ASSF). Valve-regulated lead-acid (VRLA) batteries in absorbent glass mat (AGM) technology are applied in vehicles with micro-hybrid power system (MHPS). In both part I and part II of this publication vehicles with MHPS and AGM batteries are subject to a field operational test (FOT). Test vehicles with conventional power system (CPS) and flooded batteries were used as a reference. In the FOT sample batteries were mounted several times and electrically tested in the laboratory intermediately. Vehicle- and battery-related diagnosis data were read out for each test run and were matched with laboratory data in a data base. The FOT data were analyzed by the use of two-dimensional, nonparametric kernel estimation for clear data presentation. The data show that capacity loss in the MHPS is comparable to the CPS. However, the influence of mileage performance, which cannot be separated, suggests that battery stress is enhanced in the MHPS although a battery refresh function is applied. Anyway, the FOT demonstrates the unsuitability of flooded batteries for the MHPS because of high early capacity loss due to acid stratification and because of vanishing cranking performance due to increasing internal resistance. Furthermore, the lack of dynamic charge acceptance for high energy regeneration efficiency is illustrated. Under the presented FOT conditions charge acceptance of lead-acid (LA) batteries decreases to less than one third for about half of the sample batteries compared to new battery condition. In part II of this publication FOT data are presented by multiple regression analysis (Schaeck et al., submitted for publication [1]).

  5. Erbium concentration dependent absorbance in tellurite glass

    SciTech Connect

    Sazali, E. S. Rohani, M. S. Sahar, M. R. Arifin, R. Ghoshal, S. K. Hamzah, K.

    2014-09-25

    Enhancing the optical absorption cross-section in topically important rare earth doped tellurite glasses is challenging for photonic devices. Controlled synthesis and detailed characterizations of the optical properties of these glasses are important for the optimization. The influence of varying concentration of Er{sup 3+} ions on the absorbance characteristics of lead tellurite glasses synthesized via melt-quenching technique are investigated. The UV-Vis absorption spectra exhibits six prominent peaks centered at 490, 526, 652, 800, 982 and 1520 nm ascribed to the transitions in erbium ion from the ground state to the excited states {sup 4}F{sub 7/2}, {sup 2}H{sub 11/2}, {sup 4}F{sub 9/2}, {sup 4}I{sub 9/2}, {sup 2}H{sub 11/2} and {sup 4}I{sub 13/2}, respectively. The results are analyzed by means of optical band gap E{sub g} and Urbach energy E{sub u}. The values of the energy band gap are found decreased from 2.82 to 2.51 eV and the Urbach energy increased from 0.15 to 0.24 eV with the increase of the Er{sub 2}O{sub 3} concentration from 0 to 1.5 mol%. The excellent absorbance of the prepared tellurite glasses makes them suitable for fabricating solid state lasers.

  6. Microwave Absorbing Properties of Metallic Glass/Polymer Composites

    DTIC Science & Technology

    2011-09-01

    Technical Report ARWSB-TR-11022 Microwave Absorbing Properties of Metallic Glass/Polymer Composites Stephen Bartolucci...Technical 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Microwave Absorbing Properties of Metallic Glass/Polymer Composites 5a. CONTRACT...this study, the microwave absorption characteristics of metallic glass / polymer composites were investigated. Electromagnetic wave absorption

  7. Electrical resistance tests of glass mat type separators

    SciTech Connect

    Lind, A.L.

    1997-12-01

    Resistance measurement of glass mat separators for VRLA batteries is necessary for proper design selection. The equipment described makes sample comparison possible under compression in either flooded or starved condition. The Palico Instrument Labs method operates on the principle of measuring the change in resistance of test cell as electrolyte level is changed, first with and then without the separator sample. Since the separator can only be removed by removing the Model 903 Carrier and then reinserting after separator removal, stability to test readings and accurate measurement of electrolyte level are essential. Measurements are made with a reversing polarity DC current in all of the Palico resistance test equipment which closely match conditions found in the final battery.

  8. A novel method for preparing the antibacterial glass fibre mat using laser treatment

    NASA Astrophysics Data System (ADS)

    Wiener, Jakub; Shahidi, Sheila; Mkhululi Goba, Makabongwe; Šašková, Jana

    2014-02-01

    In this study, CO2 laser treatment was used as a novel method for creating antibacterial properties on glass mat. Different metallic salts such as CuO, ZnO and AgNO3 were even applied on surface of glass fiber mat, then irradiated with the laser light beam (100 μs). Metal particles were deposited on the surface of samples, and the antibacterial has been developed, through incorporation of metal particles on glass mats. The antibacterial properties of the fabrics were connected with the presence of metal particles on their surface. The amounts of metal particles on the surface were compared using X-ray fluorescence (XRF) and energy dispersive X-ray spectrometer (EDS). Also the morphological properties of the fabrics were observed using a scanning electron microscope (SEM). The experimental work suggests that the change in properties induced by laser can effect an improvement in certain textile products.

  9. Alkaline composite PEO-PVA-glass-fibre-mat polymer electrolyte for Zn-air battery

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lin, Sheng-Jen

    An alkaline composite PEO-PVA-glass-fibre-mat polymer electrolyte with high ionic conductivity (10 -2 S cm -1) at room temperature has been prepared and applied to solid-state primary Zn-air batteries. The electrolyte shows excellent mechanical strength. The electrochemical characteristics of the batteries were experimentally investigated by means of ac impedance spectroscopy and galvanostatic discharge. The results indicate that the PEO-PVA-glass-fibre-mat composite polymer electrolyte is a promising candidate for application in alkaline primary Zn-air batteries.

  10. Training traditional birth attendants to use misoprostol and an absorbent delivery mat in home births.

    PubMed

    Prata, Ndola; Quaiyum, Md Abdul; Passano, Paige; Bell, Suzanne; Bohl, Daniel D; Hossain, Shahed; Azmi, Ashrafi Jahan; Begum, Mohsina

    2012-12-01

    A 50-fold disparity in maternal mortality exists between high- and low-income countries, and in most contexts, the single most common cause of maternal death is postpartum hemorrhage (PPH). In Bangladesh, as in many other low-income countries, the majority of deliveries are conducted at home by traditional birth attendants (TBAs) or family members. In the absence of skilled birth attendants, training TBAs in the use of misoprostol and an absorbent delivery mat to measure postpartum blood loss may strengthen the ability of TBAs to manage PPH. These complementary interventions were tested in operations research among 77,337 home births in rural Bangladesh. The purpose of this study was to evaluate TBAs' knowledge acquisition, knowledge retention, and changes in attitudes and practices related to PPH management in home births after undergoing training on the use of misoprostol and the blood collection delivery mat. We conclude that the training was highly effective and that the two interventions were safely and correctly used by TBAs at home births. Data on TBA practices indicate adherence to protocol, and 18 months after the interventions were implemented, TBA knowledge retention remained high. This program strengthens the case for community-based use of misoprostol and warrants consideration of this intervention as a potential model for scale-up in settings where complete coverage of skilled birth attendants (SBAs) remains a distant goal.

  11. Application of glass-fiber reinforced plastic (GRP) mud-mats for Daria-A platform

    SciTech Connect

    Bertorelli, D.; Spessa, A.

    1994-12-31

    A review of the experience gained with glass-fiber reinforced plastic (GRP) mud-mat materials used for the Garibaldi-C jacket, in the Adriatic sea, has shown that this solution can result in substantial cost savings. Therefore, Agip has investigated a further use of GRP mud-mats for the Daria-A platform as a means of reducing the lifting weight of the jacket and, moreover, to negate the requirement for additional buoyancy tanks during the free flotation and upending phases. Two possible solutions, the ``pultrusion`` and the ``lamination`` techniques, have been investigated to fabricate sandwich panels for the mud-mats. In this paper these two technologies are discussed with respect to their application to the construction and they are compared on a performance and cost basis.

  12. Pressure influence on the structural characteristics of modified absorptive glass mat separators: A standard contact porosimetry study

    NASA Astrophysics Data System (ADS)

    Burashnikova, M. M.; Khramkova, T. S.; Kazarinov, I. A.; Shmakov, S. L.

    2015-09-01

    The article presents a comparative analysis of the structural characteristics of absorptive glass mats manufactured by "Hollingsworth & Vose" (a 2.8 mm thickness) and "Bernard Dumas" (a 3.0 mm thickness) modified by impregnation with polymeric emulsions based on polyvinylidene fluoride, a polyvinylpyrrolidone styrene copolymer, and polytetrafluoroethylene, by means of standard contact porosimetry. The key study is influence of features of the porous structure on the compression properties, the rate of wicking, and the oxygen cycle efficiency in lead-acid battery mock-ups under several plate-group compression pressures. It is found that the treatment of the absorptive glass mat separators with polymeric emulsions leads to redistribution of their pores by size. An increased pressure in the electrode unit insignificantly changes the pore structure of the modified absorptive glass mat separators, and the oxygen cycle efficiency rises in comparison with unmodified separators.

  13. Developments in absorptive glass mat separators for cycling applications and 36 V lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Toniazzo, V.; Lambert, U.

    The major markets for valve-regulated lead-acid (VRLA) batteries are undergoing a radical upheaval. In particular, the telecommunications industry requires more reliable power supplies, and the familiar 12 V electrical system in cars will probably be soon replaced by a 36/42 V system, or by other electrical systems if part of the automotive market is taken over by hybrid electrical vehicles (HEVs). In order to meet these new challenges and enable VRLA batteries to provide a satisfactory life in float and cycling applications in the telecommunication field, or in the high-rate-partial-state-of-charge service required by both 36/42 V automobiles and HEVs, the lead-acid battery industry has to improve substantially the quality of present VRLA batteries based on absorptive glass mat (AGM) technology. Therefore, manufacturing steps and cell components have to be optimized, especially AGM separators as these are key components for better production yields and battery performance. This paper shows how the optimal segregation of the coarse and fine fibres in an AGM separator structure can improve greatly the properties of the material. The superior capillarity, springiness and mechanical properties of the 100% glass Amerglass multilayer separator compared with commercial monolayer counterparts with the same specific surface-area is highlighted.

  14. Comparison between viscous elastic plastic behaviour of the composites reinforced with plain glass fabric and chopped strand mat

    NASA Astrophysics Data System (ADS)

    Stanciu, M. D.; Harapu, A.; Teodorescu Drăghicescu, H.; Curtu, I.; Savin, A.

    2016-08-01

    Composite structures are used mainly two types of reinforcement materials: woven glass fabric and the chopped strand mat, each contributing either to increase the resistance of the composite whole or in isotropic distribution of stresses. This paper presents a comparison of the visco-elastic characteristics of composites reinforced with glass fabric and the chopped strand mat and the breaking mode of the two types of the composite. The first type of samples contain three layers of chopped strand mat known as MAT with density of 450g/m2 and 225g/m2) and the second type is composed of four layers of woven glass fabric type RT500 (density of 500g/m2). Both specimens were cut in accordance with EN ISO 527-2 SR. Characteristic curve of the two types of specimens highlights visco-elastic-plastic behavior which largely depends on the type of reinforcement used as the matrix resin is the same in both cases (orthophthalic polyester resin). Breaking mode of those types of specimens were observed and analyzed by electronic microscope.

  15. Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries

    PubMed Central

    Zhu, Yusong; Wang, Faxing; Liu, Lili; Xiao, Shiyin; Yang, Yaqiong; Wu, Yuping

    2013-01-01

    Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm−1), high Li+ ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost. PMID:24216756

  16. Cheap glass fiber mats as a matrix of gel polymer electrolytes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhu, Yusong; Wang, Faxing; Liu, Lili; Xiao, Shiyin; Yang, Yaqiong; Wu, Yuping

    2013-11-01

    Lithium ion batteries (LIBs) are going to play more important roles in electric vehicles and smart grids. The safety of the current LIBs of large capacity has been remaining a challenge due to the existence of large amounts of organic liquid electrolytes. Gel polymer electrolytes (GPEs) have been tried to replace the organic electrolyte to improve their safety. However, the application of GPEs is handicapped by their poor mechanical strength and high cost. Here, we report an economic gel-type composite membrane with high safety and good mechanical strength based on glass fiber mats, which are separator for lead-acid batteries. The gelled membrane exhibits high ionic conductivity (1.13 mS cm-1), high Li+ ion transference number (0.56) and wide electrochemical window. Its electrochemical performance is evaluated by LiFePO4 cathode with good cycling. The results show this gel-type composite membrane has great attraction to the large-capacity LIBs requiring high safety with low cost.

  17. Preparation of calcium silicate absorbent from recycled glass

    SciTech Connect

    Arthur, L.F.; Rochelle, G.T.

    1998-09-01

    Calcium silicate hydrates were prepared from hydrated lime and post-consumer recycled glass in an aqueous slurry. These high surface area solids have shown promise as alkaline sorbents for environmental gas cleaning applications. Surface area was monitored at a variety of reaction conditions. The rate of surface area formation was found to be directly proportional to the initial surface area of the glass. At 92 C, the addition of gypsum to the system had a significant positive effect, forming solids with surface areas up to 125 m{sup 2}/g over long reaction times. Increasing the temperature from 92 C to 120 C increased the initial rate of surface area formation, however the rate decreased over time and the ultimate surface area was higher at 92 C. The addition of gypsum or calcium chloride to the reaction at 120 C increased the ultimate surface area, but not to the extent of the 92 C product. Up to a surface area of {approximately}100 m{sup 2}/g, sorbents formed at 92 C with gypsum were not affected by agitation, nor by solids content between 20--50% under non-agitated conditions. At reaction times after this point, surface area increased slightly with water content and more significantly with agitation. In addition, the dissolution of silica from glass was measured and was found to be faster than the rate of sorbent formation.

  18. Absorbed dose measurements on external surface of Kosmos-satellites with glass thermoluminescent detectors.

    PubMed

    Akatov YuA; Arkhangelsky, V V; Kovalev, E E; Spurny, F; Votochkova, I

    1989-01-01

    In this paper we present absorbed dose measurements with glass thermoluminescent detectors on external surface of satellites of Kosmos-serie flying in 1983-87. Experiments were performed with thermoluminescent aluminophosphate glasses of thicknesses 0.1, 0.3, 0.4, 0.5, and 1 mm. They were exposed in sets of total thickness between 5 and 20 mm, which were protected against sunlight with thin aluminized foils. In all missions, extremely high absorbed dose values were observed in the first layers of detectors, up to the thickness of 0.2 to 0.5 gcm-2. These experimental results confirm that, during flights at 250 to 400 km, doses on the surface of the satellites are very high, due to the low energy component of the proton and electron radiation.

  19. Amplification of electrolyte uptake in the absorptive glass mat (AGM) separator for valve regulated lead acid (VRLA) batteries

    NASA Astrophysics Data System (ADS)

    Kumar, Vijay; Kameswara Rao, P. V.; Rawal, Amit

    2017-02-01

    Absorptive glass mat (AGM) separators are widely used for valve regulated lead acid (VRLA) batteries due to their remarkable fiber and structural characteristics. Discharge performance and recharge effectiveness of VRLA batteries essentially rely on the distribution and saturation levels of the electrolyte within the AGM separator. Herein, we report an analytical model for predicting the wicking characteristics of AGM battery separators under unconfined and confined states. The model of wicking behavior of AGM is based upon Fries and Dreyer's approach that included the effect of gravity component which was neglected in classic Lucas-Washburn's model. In addition, the predictive model of wicking accounted for realistic structural characteristics of AGM via orientation averaging approach. For wicking under confined state, the structural parameters have been updated under defined level of compressive stresses based upon the constitutive equation derived for a planar network of fibers in AGM under transverse loading conditions. A comparison has been made between the theoretical models and experimental results of wicking behavior under unconfined and confined states. Most importantly, the presented work has highlighted the questionable validity of classic Lucas-Washburn model for predicting the wicking characteristics of AGM separator over longer time duration.

  20. Experimental evidence for an absorbing phase transition underlying yielding of a soft glass

    NASA Astrophysics Data System (ADS)

    Nagamanasa, K. Hima; Gokhale, Shreyas; Sood, A. K.; Ganapathy, Rajesh

    2014-03-01

    A characteristic feature of solids ranging from foams to atomic crystals is the existence of a yield point, which marks the threshold stress beyond which a material undergoes plastic deformation. In hard materials, it is well-known that local yield events occur collectively in the form of intermittent avalanches. The avalanche size distributions exhibit power-law scaling indicating the presence of self-organized criticality. These observations led to predictions of a non-equilibrium phase transition at the yield point. By contrast, for soft solids like gels and dense suspensions, no such predictions exist. In the present work, by combining particle scale imaging with bulk rheology, we provide a direct evidence for a non-equilibrium phase transition governing yielding of an archetypal soft solid - a colloidal glass. The order parameter and the relaxation time exponents revealed that yielding is an absorbing phase transition that belongs to the conserved directed percolation universality class. We also identified a growing length scale associated with clusters of particles with high Debye-Waller factor. Our findings highlight the importance of correlations between local yield events and may well stimulate the development of a unified description of yielding of soft solids.

  1. Optical properties of transparent cobalt-containing magnesium aluminosilicate glass-ceramics doped with gallium oxide for saturable absorbers

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Skoptsov, N. A.; Dymshits, O. S.; Malyarevich, A. M.; Yumashev, K. V.; Zhilin, A. A.; Alekseeva, I. P.

    2016-10-01

    Transparent glass-ceramic materials based on glasses of the MgO-Al2O3-SiO2-TiO2 system doped with CoO and Ga2O3 are synthesized. The secondary heat treatment of the initial glasses at temperatures of 800-950°C leads to precipitation of nanosized (6-7 nm) crystals of magnesium aluminogallium spinel doped with cobalt ions and magnesium aluminotitanate solid solutions. The optical absorption spectra of the initial glass and glass-ceramic materials are studied. It is shown that the absorption band caused by the 4 A 2(4F)→ 4 T 1(4 F) transitions of tetrahedrally coordinated Co2+ ions in glass-ceramics with nanosized Co:Mg(Al,Ga)2O4 crystals is shifted to longer wavelengths (up to 1.67 µm) compared to the position of this band in materials with Co:MgAl2O4 crystals. The synthesized glass-ceramics are characterized by a relatively low saturation fluence FS 0.5 ± 0.1 J/cm2 at a wavelength of 1.54 µm, as well as by a high radiation resistance to nanosecond laser pulses, which is no lower than 15 ± 2 J/cm2. This explains their attractiveness as materials for saturable absorbers for erbium lasers emitting in the spectral range 1.5-1.7 µm.

  2. Micro-structural design and function of an improved absorptive glass mat (AGM) separator for valve-regulated lead-acid batteries

    NASA Astrophysics Data System (ADS)

    Nakayama, Y.; Kishimoto, K.; Sugiyama, S.; Sakaguchi, S.

    Two important properties of absorptive glass mat (AGM) separators are examined in order to design optimum separators for advanced valve-regulated lead-acid (VRLA) batteries. Acid stratification in the separator depends on its micro-glass-fibre diameter, and it is found that the extent of stratification can be estimated based on hydrodynamics theory. Decreasing the plate-group pressure of the separator in the wetted state is also investigated, and it is considered that the phenomenon is caused by the balance between the fibre strength and the surface tension of acid solution. Given these results, the way to design AGM separators according to purpose has been identified. Accordingly, a new AGM separator has been developed and this functions both to suppress stratification and to maintain plate-group pressure.

  3. In-situ Curing Strain Monitoring of a Flat Plate Residual Stress Specimen Using a Chopped Stand Mat Glass/Epoxy Composite as Test Material

    NASA Astrophysics Data System (ADS)

    Jakobsen, J.; Skordos, A.; James, S.; Correia, R. G.; Jensen, M.

    2015-12-01

    The curing stresses in a newly proposed bi-axial residual stress testing configuration are studied using a chopped strand mat glass/epoxy specimen. In-situ monitoring of the curing is conducted using dielectric and fibre Bragg grating sensors. It is confirmed that a bi-axial residual stress state can be introduced in the specimens during curing and a quantification of its magnitude is presented. An alternative decomposition method used for converting the dielectric signal into a material state variable is proposed and good agreement with models found in the literature is obtained. From the cure cycles chosen it is suggested that any stress build up in the un-vitrified state is relaxed immediately and only stress build up in the vitrified state contributes to the residual stress state in the specimen.

  4. Characterization of porous glass-ceramic material as absorber of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Kazmina, O.; Suslyaev, V.; Dushkina, M.; Semukhin, B.

    2015-04-01

    Investigations of a foam glass-ceramic material synthesized from raw siliceous earth material by the two-stage method at temperatures below 950°C have demonstrated the improvement of its physic mechanical properties in comparison with foam glass synthesized from glass cullet. This material actively interacts with microwaves and can be used for the development of protective screens reducing the adverse effect of microwaves on biological objects, anechoic chambers, and rooms with low level of electromagnetic background noise. Spectra of the transmission and absorption coefficients and of the complex dielectric permittivity for frequencies in the range 26-260 GHz are presented. The observed effects demonstrate the existence of regions with partial and total reflection arising on the glass-pore boundary and of the microwave interaction with ultradisperse carbon particles that remain after foaming with incomplete frothier transition from the soot to the gas phase.

  5. Use of glass fiber-reinforced plastic as an absorber in limestone wet flue gas desulfurization.

    PubMed

    Lin, Haibo

    2008-10-01

    The choice of materials for the spraying and oxidation of pipes directly affect the operation in limestone wet flue gas desulfurization (FGD). There is reason to consider using glass fiber-reinforced plastic (FRP) instead of expensive high nickel alloy for the spraying and oxidation of pipes.

  6. Gelled electrolytes for use in absorptive glass mat valve-regulated lead-acid (AGM VRLA) batteries working under 100% depth of discharge conditions

    NASA Astrophysics Data System (ADS)

    Tantichanakul, Titiporn; Chailapakul, Orawon; Tantavichet, Nisit

    2011-10-01

    Gelled electrolytes prepared from fumed silica for use in absorptive glass mat valve-regulated lead-acid (AGM VRLA) batteries and the effect of veratraldehyde addition on the electrochemical behavior and performance of AGM VRLA batteries are investigated. Cyclic voltammetry is used to investigate differences in the electrochemical behaviors of nongelled and gelled electrolytes and between gelled electrolytes with and without veratraldehyde. Battery performance is tested under 100% depth of discharge (100% DoD) conditions at both low- (0.1 C) and high- (1 C) rate discharges. The addition of silica or veratraldehyde does not affect the main reaction of the lead-acid batteries but tends to suppress the hydrogen evolution reaction. AGM VRLA batteries with gelled electrolytes have a higher discharge capacity and longer cycle life than the conventional nongel AGM VRLA batteries. The addition of 0.005% (w/v) veratraldehyde further improves battery performance, but higher (0.01%, w/v) veratraldehyde concentrations reduce it and correlate with the enhanced growth of lead sulfate crystals. The AGM VRLA battery prepared from a gelled electrolyte containing 0.005% (w/v) veratraldehyde provides the best battery performance in every operating temperature studied (0-60 °C).

  7. Absorptive glass mat separator surface modification and its influence on the heat generation in valve-regulated lead-acid battery

    NASA Astrophysics Data System (ADS)

    Drenchev, Boris; Dimitrov, Mitko; Boev, Victor; Aleksandrova, Albena

    2015-04-01

    This paper presents the results from a comparative study between two types of valve-regulated lead-acid battery cells, with uncoated and polymer composite coated absorptive glass mat (AGM) separators. The volt-ampere characteristics of the studied cells, recorded at different ambient temperatures, show that the cells with polymer coated separators have significantly lower overcharge (recombinant) current than the cells with conventional untreated AGM separator. During overcharge, the higher recombinant current in the cells with plain separator leads to higher cell temperature than that of the cells with polymer coated AGM separator. The possibility to avoid thermal runaway (TR) is also illustrated during polarization of the cells at 2.65 V. After 320 h, a conventional cell has C/4 current (trend to TR), while the cells with composite coating sustain low (C/26) constant current for long period of time (at least 650 h). The cycle life test indicates stable operation of the cells with coated separator, while the conventional cell reaches high recombinant current and thus, it is susceptible to thermal runaway phenomena.

  8. Preparation and microwave absorbing property of Ni-Zn ferrite-coated hollow glass microspheres with polythiophene

    NASA Astrophysics Data System (ADS)

    Li, Lindong; Chen, Xingliang; Qi, Shuhua

    2016-11-01

    The composite of hollow glass microspheres (HMG) coated by Ni0.7Zn0.3Fe2O4 particles was fabricated via sol-gel method, and then the ternary composite (HMG/Ni0.7Zn0.3Fe2O4/PT) was synthesized by in situ polymerization. The electrical property, magnetic performance and reflection loss of the composites were measured, and the results suggest that the conductivity and the saturation magnetization (Ms) of HMG/Ni0.7Zn0.3Fe2O4/PT reach 6.87×10-5 S/cm and 11.627 emu/g, respectively. The ternary composite has good microwave absorbing properties (Rmin=-13.79 dB at 10.51 GHz) and the bandwidth less than -10 dB can reach 2.6 GHz (from 9.4 to 12.0 GHz) in X band (8.2-12.4 GHz). The morphology and chemical structure of the samples were measured through scanning electron microscopy (SEM), X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). This paper also analyzes the relationship between the reflection loss of the absorber and its thickness.

  9. Effect of laser shock peening without absorbent coating on the mechanical properties of Zr-based bulk metallic glass

    NASA Astrophysics Data System (ADS)

    Zhu, Yunhu; Fu, Jie; Zheng, Chao; Ji, Zhong

    2015-12-01

    In this work, laser shock peening without absorbent coating (LSPwC) was employed to Zr41.2Ti13.8Cu12.5Ni10Be22.5 (vit1) bulk metallic glass in order to improve its mechanical properties. The phase structure and thermal properties of the as-cast and LSPwC treated samples were characterized by X-ray diffraction, transmission electron microscope and differential scanning calorimeter. Three-point bending fracture tests of vit1 were performed on universal testing machine at room temperature with loading rate of 0.1 mm/min. The results showed that LSPwC enhanced the plasticity of vit1, and the plastic deflection increased by 23%. This enhancement could be attributed to the generation of crystalline phase and more free volume as well as the complex residual stresses induced by LSPwC. The optical profiling test showed that the LSPwC increased the surface roughness of vit1. Scanning electron microscope measurements on the fracture surface of vit1 revealed that high dense vein patterns were formed on cross section of the LSPwC treated sample.

  10. Composition for absorbing hydrogen

    DOEpatents

    Heung, Leung K.; Wicks, George G.; Enz, Glenn L.

    1995-01-01

    A hydrogen absorbing composition. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  11. Composition for absorbing hydrogen

    DOEpatents

    Heung, L.K.; Wicks, G.G.; Enz, G.L.

    1995-05-02

    A hydrogen absorbing composition is described. The composition comprises a porous glass matrix, made by a sol-gel process, having a hydrogen-absorbing material dispersed throughout the matrix. A sol, made from tetraethyl orthosilicate, is mixed with a hydrogen-absorbing material and solidified to form a porous glass matrix with the hydrogen-absorbing material dispersed uniformly throughout the matrix. The glass matrix has pores large enough to allow gases having hydrogen to pass through the matrix, yet small enough to hold the particles dispersed within the matrix so that the hydrogen-absorbing particles are not released during repeated hydrogen absorption/desorption cycles.

  12. Effect of weight fraction of carbon black and number of plies of E-glass fiber to reflection loss of E-glass/ripoxy composite for radar absorbing structure (RAS)

    NASA Astrophysics Data System (ADS)

    Widyastuti, Ramadhan, Rizal; Ardhyananta, Hosta; Zainuri, Mochamad

    2013-09-01

    Nowadays, studies on investigating radar absorbing structure (RAS) using fiber reinforced polymeric (FRP) composite materials are becoming popular research field because the electromagnetic properties of FRP composites can be tailored effectively by just adding some electromagnetic powders, such as carbon black, ferrite, carbonyl iron, and etc., to the matrix of composites. The RAS works not only as a load bearing structure to hold the antenna system, but also has the important function of absorbing the in-band electromagnetic wave coming from the electromagnetic energy of tracking systems. In this study, E-glass fiber reinforced ripoxy resin composite was fabricated by blending the conductive carbon black (Ketjenblack EC300J) with the binder matrix of the composite material and maximizing the coefficient of absorption more than 90% (more than -10 dB) within the X-band frequency (8 - 12 GHz). It was measured by electrical conductivity (LCR meter) and vector network analyzer (VNA). Finally, the composite RAS with 0.02 weight fraction of carbon black and 4 plies of E-glass fiber showed thickness of 2.1 mm, electrical conductivity of 8.33 × 10-6 S/m, and maximum reflection loss of -27.123 dB, which can absorb more than 90% of incident EM wave throughout the entire X-band frequency range, has been developed.

  13. Enhanced microwave absorption performance of lightweight absorber based on reduced graphene oxide and Ag-coated hollow glass spheres/epoxy composite

    SciTech Connect

    Wang, Junpeng; Sun, Yu; Chen, Wei; Wang, Tao; Xu, Renxin; Wang, Jun

    2015-04-21

    Using a combination of Ag-coated hollow glass spheres (HGS@Ag) and a small quantity of graphene sheets within the epoxy matrix, we have prepared a novel lightweight high efficiency microwave absorption composite. Compared with pure HGS@Ag and graphene composite, the −10 dB absorption bandwidth and the minimum reflection loss of the novel composite are improved. Reflection loss exceeding −20 dB is obtained for composites in a wide frequency range and the minimum reflection loss reaches −46 dB while bandwidth less than −10 dB can reach up to 4.1 GHz when an appropriate absorber thickness between 2 and 3.5 mm is chosen. The enhanced microwave absorption performance of the novel composite is due to the enhanced dielectric response, enhanced conductivity, and the trap of electromagnetic radiation with increased propagation paths by multiple reflections.

  14. Mat2exo

    SciTech Connect

    2012-09-11

    MAT2EXO is a program which translates mesh data from Matlab mat-file format to Exodus II format. This tool is the inverse of the commonly used tool exo2mat which translates Exodus II data to the Matlab mat-file format. These tools provide a means for preprocessing an Exodus II model file or postprocessing an Exodus II results file using Matlab

  15. Effects of absorbed hydrogen on the electronic properties of (Zr2Fe)(1-x)H(x) metallic glasses.

    PubMed

    Novak, M; Kokanović, I

    2012-06-13

    The electrical conductivity (σ) of hydrogen doped (Zr(2)Fe)(1-x)H(x) metallic glasses has been measured in the temperature range from 290 down to 5 K. The decrease of the room temperature conductivity and the increase of its temperature coefficient are explained as consequences of increased disorder due to hydrogen doping. σ(T) for (Zr(2)Fe)(1-x)H(x) metallic glasses at low temperatures decreases with the increase of temperature, forming a minimum at T(min), before it starts a monotonic increase with increasing temperature. Both the functional forms and the magnitudes of the observed σ(T) are interpreted in terms of weak localization, electron-electron interaction and spin-fluctuation effects. Our results reveal that the electron-phonon scattering rate varies with the square of temperature from low temperatures up to 100 K and changes behaviour to a linear form at higher temperatures. At low temperatures, the minimum in σ(T) is shifted to higher temperatures, which is ascribed to the increase of the screening parameter of the Coulomb interaction F* associated with the enhancement of the spin fluctuations arising from the increase of the hydrogen doping. The spin-orbit scattering rate and the electron diffusion constant are reduced by hydrogen doping.

  16. Advanced neutron absorber materials

    DOEpatents

    Branagan, Daniel J.; Smolik, Galen R.

    2000-01-01

    A neutron absorbing material and method utilizing rare earth elements such as gadolinium, europium and samarium to form metallic glasses and/or noble base nano/microcrystalline materials, the neutron absorbing material having a combination of superior neutron capture cross sections coupled with enhanced resistance to corrosion, oxidation and leaching.

  17. ProMat

    SciTech Connect

    2008-06-12

    ProMAT is a software tool for statistically analyzing data from enzyme-linked immunosorbent assay microarray experiments. The software estimates standard curves, sample protein concentrations and their uncertainties for multiple assays. ProMAT generates a set of comprehensive figures for assessing results and diagnosing process quality. The tool is available for Windows or Mac, and is distributed as open-source Java and R code

  18. MatMCNP

    SciTech Connect

    2015-10-19

    A code for generating MCNP material cards (MatMCNP) has been written and verified for naturally occurring, stable isotopes. The program allows for material specification as either atomic or weight percent (fractions). MatMCNP also permits the specification of enriched lithium, boron, and/or uranium. In addition to producing the material cards for MCNP, the code calculates the atomic (or number) density in atoms/barn-cm as well as the multiplier that should be used to convert neutron and gamma fluences into dose in the material specified.

  19. Investigation of VEGGIE Root Mat

    NASA Technical Reports Server (NTRS)

    Subbiah, Arun M.

    2013-01-01

    VEGGIE is a plant growth facility that utilizes the phenomenon of capillary action as its primary watering system. A cloth made of Meta Aramid fiber, known as Nomex is used to wick water up from a reservoir to the bottom of the plants roots. This root mat system is intended to be low maintenance with no moving parts and requires minimal crew interface time. Unfortunately, the water wicking rates are inconsistent throughout the plant life cycle, thus causing plants to die. Over-wicking of water occurs toward the beginning of the cycle, while under-wicking occurs toward the middle. This inconsistency of wicking has become a major issue, drastically inhibiting plant growth. The primary objective is to determine the root cause of the inconsistent wicking through experimental testing. Suspect causes for the capillary water column to break include: a vacuum effect due to a negative pressure gradient in the water reservoir, contamination of material due to minerals in water and back wash from plant fertilizer, induced air bubbles while using syringe refill method, and material limitations of Nomex's ability to absorb and retain water. Experimental testing will be conducted to systematically determine the cause of under and over-wicking. Pressure gages will be used to determine pressure drop during the course of the plant life cycle and during the water refill process. A debubbler device will be connected to a root mat in order to equalize pressure inside the reservoir. Moisture and evaporation tests will simultaneously be implemented to observe moisture content and wicking rates over the course of a plant cycle. Water retention tests will be performed using strips of Nomex to determine materials wicking rates, porosity, and absorptivity. Through these experimental tests, we will have a better understanding of material properties of Nomex, as well as determine the root cause of water column breakage. With consistent test results, a forward plan can be achieved to resolve

  20. Biogeochemistry of Microbial Mats

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.; DeVincenizi, D. (Technical Monitor)

    2002-01-01

    The hierarchical organization of microbial ecosystems determines the rates of processes that shape Earth's environment, define the stage upon which major evolutionary events occurred, and create biosignatures in sediments and atmospheres. In cyanobacterial mats, oxygenic photosynthesis provides energy, organic substrates and oxygen to the ecosystem. Incident light changes with depth in the mat, both in intensity and spectral composition, and counteracting gradients of oxygen and sulfide shape the chemical microenvironment. A combination of benefits and hazards of light, oxygen and sulfide promotes the allocation of the various essential mat processes between light and dark periods and to various depths in the mat. Microliters produce hydrogen, small organic acids, nitrogen and sulfur species. Such compounds fuel a flow of energy and electrons in these ecosystems and thus shape interactions between groups of microorganisms. Coordinated observations of population distribution, abundance, and activity for an entire community are making fundamental questions in ecology accessible. These questions address those factors that sustain the remarkable diversity of microorganisms that are now being revealed by molecular techniques. These questions also target the processes that shape the various kinds of biosignatures that we will seek, both in ancient rocks from Earth and Mars, and in atmospheres of distant planets beyond our Solar System.

  1. BIOGEOCHEMICAL STUDIES OF PHOTOSYNTHETIC MICROBIAL MATS AND THEIR BIOTA

    NASA Technical Reports Server (NTRS)

    DesMarais, David; Discipulo, M.; Turk, K.; Londry, K. L.

    2005-01-01

    Photosynthetic microbial mats offer an opportunity to define holistic functionality at the millimeter scale. At the same time. their biogeochemistry contributes to environmental processes on a planetary scale. These mats are possibly direct descendents of the most ancient biological communities; communities in which oxygenic photosynthesis might have been invented. Mats provide one of the best natural systems to study how microbial populations associate to control dynamic biogeochemical gradients. These are self- sustaining, complete ecosystems in which light energy absorbed over a dial (24 hour) cycle drives the synthesis of spatially-organized, diverse biomass. Tightly-coupled microorganisms in the mat have specialized metabolisms that catalyze transformations of carbon, nitrogen, sulfur, and a host of other elements.

  2. Internal absorber solar collector

    DOEpatents

    Sletten, Carlyle J.; Herskovitz, Sheldon B.; Holt, F. S.; Sletten, E. J.

    1981-01-01

    Thin solar collecting panels are described made from arrays of small rod collectors consisting of a refracting dielectric rod lens with an absorber imbedded within it and a reflecting mirror coated on the back side of the dielectric rod. Non-tracking collector panels on vertical walls or roof tops receive approximately 90% of solar radiation within an acceptance zone 60.degree. in elevation angle by 120.degree. or more in the azimuth sectors with a collector concentration ratio of approximately 3.0. Miniaturized construction of the circular dielectric rods with internal absorbers reduces the weight per area of glass, plastic and metal used in the collector panels. No external parts or insulation are needed as heat losses are low due to partial vacuum or low conductivity gas surrounding heated portions of the collector. The miniature internal absorbers are generally made of solid copper with black selective surface and the collected solar heat is extracted at the collector ends by thermal conductivity along the absorber rods. Heat is removed from end fittings by use of liquid circulants. Several alternate constructions are provided for simplifying collector panel fabrication and for preventing the thermal expansion and contraction of the heated absorber or circulant tubes from damaging vacuum seals. In a modified version of the internal absorber collector, oil with temperature dependent viscosity is pumped through a segmented absorber which is now composed of closely spaced insulated metal tubes. In this way the circulant is automatically diverted through heated portions of the absorber giving higher collector concentration ratios than theoretically possible for an unsegmented absorber.

  3. Crystallization and nonlinear optical properties of transparent glass-ceramics with Co:Mg(Al,Ga)2O4 nanocrystals for saturable absorbers of lasers at 1.6-1.7 μm

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Dymshits, O. S.; Skoptsov, N. A.; Malyarevich, A. M.; Zhilin, A. A.; Alekseeva, I. P.; Tsenter, M. Y.; Bogdanov, K. V.; Mateos, X.; Yumashev, K. V.

    2017-04-01

    Transparent glass-ceramics (GCs) containing nanocrystals of Co:Mg(Al,Ga)2O4 spinel and Co:magnesium gallium aluminotitanate solid solutions are synthesized by secondary heat-treatments of the magnesium aluminosilicate glass nucleated by TiO2 and doped with Ga2O3 and CoO. Optical spectroscopy confirms that Co2+ ions located in the initial glass in octahedral and tetrahedral positions, enter the Mg(Al,Ga)2O4 nanocrystals predominantly in tetrahedral sites and the fraction of tetrahedrally coordinated ions increases gradually with the heat-treatment temperature. The feature of these GCs is a long-wavelength shift of the absorption band related to the 4A2(4F)→4T1(4F) transition of Co2+ ions (up to 1.67 μm) as compared with that for Co:MgAl2O4 single crystals. An increase of the heat-treatment temperature from 800 to 950 °C leading to an increase of the fraction and size of spinel crystals allowed increasing the peak absorption within this band while keeping the saturation intensity within the range 0.5…0.7 J/cm2 and the recovery time in the range 240…335 ns. The developed GCs are promising as saturable absorbers for erbium lasers emitting at 1.6-1.7 μm.

  4. Method for making glass nonfogging

    DOEpatents

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

    1979-01-01

    A method for rendering glass nonfogging (to condensation fog) by sandwiching the glass between two electrodes such that the glass functions as the dielectric of a capacitor, a large alternating current (AC) voltage is applied across the electrodes for a selected time period causing the glass to absorb a charge, and the electrodes are removed. The glass absorbs a charge from the electrodes rendering it nonfogging. The glass surface is undamaged by application of the AC voltage, and normal optical properties are unaffected. This method can be applied to optical surfaces such as lenses, auto windshields, mirrors, etc., wherever condensation fog on glass is a problem.

  5. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    NASA Astrophysics Data System (ADS)

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-11-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  6. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber

    PubMed Central

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte. PMID:25411566

  7. Improving the efficiency of cadmium sulfide-sensitized titanium dioxide/indium tin oxide glass photoelectrodes using silver sulfide as an energy barrier layer and a light absorber.

    PubMed

    Chen, Chong; Zhai, Yong; Li, Chunxi; Li, Fumin

    2014-01-01

    Cadmium sulfide (CdS) and silver sulfide (Ag2S) nanocrystals are deposited on the titanium dioxide (TiO2) nanocrystalline film on indium tin oxide (ITO) substrate to prepare CdS/Ag2S/TiO2/ITO photoelectrodes through a new method known as the molecular precursor decomposition method. The Ag2S is interposed between the TiO2 nanocrystal film and CdS nanocrystals as an energy barrier layer and a light absorber. As a consequence, the energy conversion efficiency of the CdS/Ag2S/TiO2/ITO electrodes is significantly improved. Under AM 1.5 G sunlight irradiation, the maximum efficiency achieved for the CdS(4)/Ag2S/TiO2/ITO electrode is 3.46%, corresponding to an increase of about 150% as compared to the CdS(4)/TiO2/ITO electrode without the Ag2S layer. Our experimental results show that the improved efficiency is mainly due to the formation of Ag2S layer that may increase the light absorbance and reduce the recombination of photogenerated electrons with redox ions from the electrolyte.

  8. Compositions of constructed microbial mats

    DOEpatents

    Bender, Judith A.; Phillips, Peter C.

    1999-01-01

    Compositions and methods of use of constructed microbial mats, comprising cyanobacteria and purple autotrophic bacteria and an organic nutrient source, in a laminated structure, are described. The constructed microbial mat is used for bioremediation of different individual contaminants and for mixed or multiple contaminants, and for production of beneficial compositions and molecules.

  9. Validation of FRP Matting Requirements

    DTIC Science & Technology

    2016-08-01

    Civil Engineer Center to validate requirements for using Fiber Reinforced Polymer (FRP) matting as a foreign object debris cover when repairing damaged...19 2.8.2 Type B-3 polymer glue anchor...FOD cover matting solution, Fiber Reinforced Polymer (FRP), was identified as a potential replacement as the USAF airfield damage repair (ADR

  10. Sound Absorbers

    NASA Astrophysics Data System (ADS)

    Fuchs, H. V.; Möser, M.

    Sound absorption indicates the transformation of sound energy into heat. It is, for instance, employed to design the acoustics in rooms. The noise emitted by machinery and plants shall be reduced before arriving at a workplace; auditoria such as lecture rooms or concert halls require a certain reverberation time. Such design goals are realised by installing absorbing components at the walls with well-defined absorption characteristics, which are adjusted for corresponding demands. Sound absorbers also play an important role in acoustic capsules, ducts and screens to avoid sound immission from noise intensive environments into the neighbourhood.

  11. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  12. Capillography of Mats of Nanofibers

    NASA Technical Reports Server (NTRS)

    Noca, Flavio; Sansom, Elijah; Zhou, Jijie; Gharib, Mory

    2008-01-01

    Capillography (from the Latin capillus, 'hair', and the Greek graphein, to write ) is a recently conceived technique for forming mats of nanofibers into useful patterns. The concept was inspired by experiments on carpetlike mats of multiwalled carbon nanotubes. Capillography may have the potential to be a less-expensive, less-time-consuming alternative to electron-beam lithography as a means of nanoscale patterning for the fabrication of small devices and instruments. In capillography, one exploits the lateral capillary forces exerted on small objects that pierce the surface of a liquid. If the small objects are identical, then the forces are always attractive. Two examples of the effects of such forces are the agglomeration of small particles floating on the surface of a pond and the drawing together of hairs of a wet paintbrush upon removal of the brush from water. Because nanoscale objects brought into contact remain stuck together indefinitely due to Van der Waals forces, patterns formed by capillography remain even upon removal of the liquid. For the experiments on the mats of carbon nanotubes, a surfactant solution capable of wetting carbon nanotubes (which are ultra-hydrophobic) was prepared. The mats were wetted with the solution, then dried. Once the mats were dry, it was found that the nanotubes had become ordered into various patterns, including nestlike indentations, trenches, and various combinations thereof. It may be possible to exploit such ordering effects through controlled wetting and drying of designated portions of mats of carbon nanotubes (and, perhaps, mats of nanofibers of other materials) to obtain patterns similar to those heretofore formed by use of electron-beam lithography. For making patterns that include nestlike indentations, it has been conjectured that it could be possible to control the nesting processes by use of electrostatic fields. Further research is needed to understand the physics of the patterning processes in order to

  13. Photoprotection: clothing and glass.

    PubMed

    Almutawa, Fahad; Buabbas, Hanan

    2014-07-01

    Ultraviolet (UV) radiation (UVR) has well-known adverse effects on the skin and eyes. Little attention is given to physical means of photoprotection, namely glass, window films, sunglasses, and clothing. In general, all types of glass block UV-B. For UV-A, the degree of transmission depends on the type, thickness, and color of the glass. Adding window films to glass can greatly decrease the transmission of UV-A. Factors that can affect the transmission of UVR through cloth include tightness of weave, thickness, weight, type of fabrics, laundering, hydration, stretch, fabric processing, UV absorbers, color, and fabric-to-skin distance.

  14. Resonance Tests on Glass Reinforced Plastic Composite Panels.

    DTIC Science & Technology

    1981-04-01

    glass -- fibre woven roving and glass - fibre chopped strand mat. BP Cellobond A2785-CV resin was used to bond the glass fibre layers to the foam. A rib was...foam slabs were filled with putty. The differences between the panels were the number of layers of glass fibre used on each side, the density of the...ORGANISATION AERONAUTICAL RESEARCH LABORATORIES MELBOURNE, VICTORIA Structures Technical Memorandum 329 RESONANCE TESTS O GLASS REINFORCED PLASTIC

  15. ON TEACHING ARCELLANA'S "THE MATS".

    ERIC Educational Resources Information Center

    ANDERSON, TOMMY R.

    FRANCISCO ARCELLANA'S "THE MATS," LIKE ANY WELL-CONSTRUCTED SHORT STORY, CAN SERVE AS AN IMPORTANT TEACHING DEVICE IN GUIDING STUDENTS, ESPECIALLY THOSE LEARNING ENGLISH AS A SECOND LANGUAGE, TO READ WITH UNDERSTANDING AND APPRECIATION, THE TECHNIQUES OF CONVERTING VERBALS BACK INTO VERBS, REPLACING ALL PRONOUNS WITH THEIR ANTECEDENTS IN PARALLEL…

  16. Stiffness of compressed fiber mats

    NASA Astrophysics Data System (ADS)

    Åström, J. A.; Mäkinen, J. P.; Hirvonen, H.; Timonen, J.

    2000-11-01

    We investigate, using an analytical and a numerical model, the in-plane stiffness of fiber mats. A mat is modeled by randomly depositing thin linear-elastic fibers on top of each other under the influence of an external pressure. The external pressure has the effect of bending the fibers over each other. The fibers are assumed rigidly bonded at contacts. For a low external pressure the stiffness of the mat deviates from that of its two-dimensional projection only by a geometrical factor, and the effective Poisson contraction is close to zero. For higher pressures, stiffness is governed by two competing effects and a maximum appears in the stiffness. The effective Poisson ratio is clearly negative in this range. An approximative analytical description is developed for the stiffness of mats formed under low external pressure. The stiffness is given as a function of only a few parameters: the degree of bonding, the dimensions of the fibers, the elastic constants of the fiber material, and the density of fibers.

  17. HiMAT in flight

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The HiMAT (Highly Maneuverable Aircraft Technology) subscale research vehicle, seen here during a research flight, was flown by the NASA Dryden Flight Research Center, Edwards, California, from mid 1979 to January 1983. The aircraft demonstrated advanced fighter technologies that have been used in the development of many modern high performance military aircraft. Two vehicles were used in the research program conducted jointly by NASA and the Air Force Flight Dynamics Laboratory, Wright-Patterson AFB, Ohio. The two vehicles, flown a total of 26 times, provided data on the use of composites, aeroelastic tailoring, close-coupled canards and winglets. They investigated the interaction of these then-new technologies upon each other. About one-half the size of a standard manned fighter and powered by a small jet engine, the HiMAT vehicles were launched from NASA's B-52 carrier aircraft at an altitude of about 45,000 feet. They were flown remotely by a NASA research pilot from a ground station with the aid of a television camera mounted in the HiMAT cockpits. Technologies tested on the HiMAT vehicles appearing later on other aircraft include the extensive use of composites common now on military and commercial aircraft; rear-mounted wing and forward canard configuration used very successfully on the X-29 research aircraft flown at Dryden; and winglets, now used on many private and commercial aircraft to lessen wingtip drag and enhance fuel savings.

  18. Sparse Coding for Alpha Matting.

    PubMed

    Johnson, Jubin; Varnousfaderani, Ehsan Shahrian; Cholakkal, Hisham; Rajan, Deepu

    2016-07-01

    Existing color sampling-based alpha matting methods use the compositing equation to estimate alpha at a pixel from the pairs of foreground ( F ) and background ( B ) samples. The quality of the matte depends on the selected ( F,B ) pairs. In this paper, the matting problem is reinterpreted as a sparse coding of pixel features, wherein the sum of the codes gives the estimate of the alpha matte from a set of unpaired F and B samples. A non-parametric probabilistic segmentation provides a certainty measure on the pixel belonging to foreground or background, based on which a dictionary is formed for use in sparse coding. By removing the restriction to conform to ( F,B ) pairs, this method allows for better alpha estimation from multiple F and B samples. The same framework is extended to videos, where the requirement of temporal coherence is handled effectively. Here, the dictionary is formed by samples from multiple frames. A multi-frame graph model, as opposed to a single image as for image matting, is proposed that can be solved efficiently in closed form. Quantitative and qualitative evaluations on a benchmark dataset are provided to show that the proposed method outperforms the current stateoftheart in image and video matting.

  19. Sparse Coding for Alpha Matting.

    PubMed

    Johnson, Jubin; Varnousfaderani, Ehsan; Cholakkal, Hisham; Rajan, Deepu

    2016-04-21

    Existing color sampling based alpha matting methods use the compositing equation to estimate alpha at a pixel from pairs of foreground (F) and background (B) samples. The quality of the matte depends on the selected (F,B) pairs. In this paper, the matting problem is reinterpreted as a sparse coding of pixel features, wherein the sum of the codes gives the estimate of the alpha matte from a set of unpaired F and B samples. A non-parametric probabilistic segmentation provides a certainty measure on the pixel belonging to foreground or background, based on which a dictionary is formed for use in sparse coding. By removing the restriction to conform to (F,B) pairs, this method allows for better alpha estimation from multiple F and B samples. The same framework is extended to videos, where the requirement of temporal coherence is handled effectively. Here, the dictionary is formed by samples from multiple frames. A multi-frame graph model, as opposed to a single image as for image matting, is proposed that can be solved efficiently in closed form. Quantitative and qualitative evaluations on a benchmark dataset are provided to show that the proposed method outperforms current state-of-the-art in image and video matting.

  20. ProMAT: protein microarray analysis tool

    SciTech Connect

    White, Amanda M.; Daly, Don S.; Varnum, Susan M.; Anderson, Kevin K.; Bollinger, Nikki; Zangar, Richard C.

    2006-04-04

    Summary: ProMAT is a software tool for statistically analyzing data from ELISA microarray experiments. The software estimates standard curves, sample protein concentrations and their uncertainties for multiple assays. ProMAT generates a set of comprehensive figures for assessing results and diagnosing process quality. The tool is available for Windows or Mac, and is distributed as open-source Java and R code. Availability: ProMAT is available at http://www.pnl.gov/statistics/ProMAT. ProMAT requires Java version 1.5.0 and R version 1.9.1 (or more recent versions) which are distributed with the tool.

  1. Hypersaline Microbial Mat Lipid Biomarkers

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.; Embaye, Tsegereda; Turk, Kendra A.; Summons, Roger E.

    2002-01-01

    Lipid biomarkers and compound specific isotopic abundances are powerful tools for studies of contemporary microbial ecosystems. Knowledge of the relationship of biomarkers to microbial physiology and community structure creates important links for understanding the nature of early organisms and paleoenvironments. Our recent work has focused on the hypersaline microbial mats in evaporation ponds at Guerrero Negro, Baja California Sur, Mexico. Specific biomarkers for diatoms, cyanobacteria, archaea, green nonsulfur (GNS), sulfate reducing, sulfur oxidizing and methanotrophic bacteria have been identified. Analyses of the ester-bound fatty acids indicate a highly diverse microbial community, dominated by photosynthetic organisms at the surface. The delta C-13 of cyanobacterial biomarkers such as the monomethylalkanes and hopanoids are consistent with the delta C-13 measured for bulk mat (-10%o), while a GNS biomarker, wax esters (WXE), suggests a more depleted delta C-13 for GNS biomass (-16%o). This isotopic relationship is different than that observed in mats at Octopus Spring, Yellowstone National Park (YSNP) where GNS appear to grow photoheterotrophic ally. WXE abundance, while relatively low, is most pronounced in an anaerobic zone just below the cyanobacterial layer. The WXE isotope composition at GN suggests that these bacteria utilize photoautotrophy incorporating dissolved inorganic carbon (DIC) via the 3-hydroxypropionate pathway using H2S or H2.

  2. Foam-mat Drying Technology: A Review.

    PubMed

    Hardy, Z; Jideani, V A

    2015-07-13

    This article reviews various aspects of foam-mat drying such as foam-mat drying processing technique, main additives used for foam-mat drying, foam-mat drying of liquid and solid foods, quality characteristics of foam-mat dried foods and economic and technical benefits for employing foam-mat drying. Foam-mat drying process is an alternative method which allows the removal of water from liquid materials and pureed materials. In this drying process, a liquid material is converted into foam that is stable by being whipped after adding an edible foaming agent. The stable foam is then spread out in sheet or mat and dried by using hot air (40 -90°C) at atmospheric pressure. Methyl cellulose (0.25 - 2%), egg white (3 - 20%), maltodextrin (0.5 - 05%) and gum Arabic (2 - 9%) are the commonly utilised additives for the foam-mat drying process at the given range, either combined together for their effectiveness or individual effect. The foam-mat drying process is suitable for heat sensitive, viscous and sticky products which cannot be dried using other forms of drying methods such as spray drying because of the state of product. More interest has developed for foam-mat drying because of the simplicity, cost effectiveness, high speed drying and improved product quality it provides.

  3. Tensile and compressive behavior of a swirl mat composite

    SciTech Connect

    Ruggles, M.B.

    1998-07-01

    The Durability of Lightweight Composite Structures Project was established at Oak Ridge National Laboratory (ORNL) by the US Department of Energy to provide the experimentally-based, durability-driven design guidelines necessary to assure long-term structural integrity of automotive composite components. The initial focus of the ORNL Durability Project was on one representative reference material--an isocyanurate (polyurethane) reinforced with continuous strand, swirl-mat E-glass. The present report describes tensile and compressive testing and results for the reference composite. Behavior trends and proportional limit are established for both tension and compression. Damage development due to tensile loading and strain rate effects are discussed.

  4. Ceramic fiber reinforced glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  5. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

    SciTech Connect

    Beam, Jake; Bernstein, Hans C.; Jay, Z.; Kozubal, Mark; Jennings, Ryan; Tringe, Susannah G.; Inskeep, William P.

    2016-02-15

    Iron oxide microbial mats are ubiquitous geobiological features on Earth and occur in extant acidic hot springs of Yellowstone National Park (YNP), WY, USA, and form as a result of microbial processes. The relative contribution of different organisms to the development of these mat ecosystems is of specific interest. We hypothesized that chemolithoautotrophic organisms contribute to the early development and production of Fe(III)-oxide mats, which could support later-colonizing heterotrophic microorganisms. Sterile glass slides were incubated in the outflow channels of two acidic geothermal springs in YNP, and spatiotemporal changes in Fe(III)-oxide accretion and abundance of relevant community members were measured. Lithoautotrophic Hydrogenobaculum spp. were first colonizers and the most abundant taxa identified during early successional stages (7 – 40 days). Populations of M. yellowstonensis colonized after ~ 7 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized after 30 days, and emerge as the dominant functional guild in mature iron oxide mats (1 – 2 cm thick) that form after 70 – 120 days. First-order rate constants of iron oxide accretion ranged from 0.05 – 0.046 day-1, and reflected the absolute amount of iron accreted. Micro- and macroscale microterracettes were identified during iron oxide mat development, and suggest that the mass transfer of oxygen limits microbial growth. This was also demonstrated using microelectrode measurements of oxygen as a function of mat depth, which showed steep gradients in oxygen from the aqueous mat interface to ~ 1 mm. The formation and succession of amorphous Fe(III)-oxide mat communities follows a predictable pattern of distinct stages and growth. The successional stages and microbial signatures observed in these extant Fe(III)-oxide mat communities may be relevant to other past or present Fe(III)-oxide mineralizing systems.

  6. Cellulose acetate electrospun fiber mats for controlled release of silymarin.

    PubMed

    Phiriyawirut, Manisara; Phaechamud, Thawatchai

    2012-01-01

    In this research, the silymarin-loaded electrospun cellulose acetate (CA) fibers were prepared which containing silymarin in various amounts (i.e., 2.5-20 wt.% based on the weight of CA powder). Incorporation of silymarin in the neat CA solution did not affect the morphology of the resulting fibers, as both the neat and the silymarin-loaded CA fibers were smooth. The average diameters of silymarin-loaded CA fiber ranged between 550-900 nm. No presence of the silymarin aggregates of any kind was observed on the surfaces of these fibers, suggesting that the silymarin was encapsulated well within the fibers. These results were confirmed by lowering the glass transition temperature and the melting temperature of the silymarin-loaded electrospun CA fibers which is determined by DSC technique. The release characteristic of silymarin from the silymarin-loaded CA fiber mats was investigated by the total immersion in the solution of 1/1 phosphate buffer/methanol medium pH 7.4 at 37 degrees C. The silymarin release from the silymarin-loaded electrospun CA fiber mat is monotonously increased to reach the maximum value at 480 min. The maximum amount of silymarin released from these materials increases with the increasing of initial silymarin loading in the spinning CA solutions. Since no aggregation of silymarin was found on the surface of the silymarin-loaded fibers, the release of the silymarin from fiber mats was mainly by the diffusion.

  7. Mechanical behavior of polyester-based woven jute/glass hybrid composites

    NASA Astrophysics Data System (ADS)

    Ahsan, Q.; Tanju, S.

    2012-06-01

    In polymer composite fabrication system, hybridization of jute fibers with synthetic fibers is one of the techniques adopted to overcome some of the limitations (poor mechanical properties and moisture resistance) that have been identified for jute fiber reinforced composites. In the present study, the effect of hybridization on mechanical properties of jute and glass mat reinforced polyester composites has been evaluated experimentally. The composites were made of glass mat, jute mat and varying layers of jute and glass mat in the polyester matrix by applying hand lay-up technique at room temperature (250C). The values of mechanical properties obtained from tensile, flexural and interlaminar shear strength (ILSS) tests show significant improvement with the increase of glass fiber content in hybrid composites. But the positive contribution from glass mat in increasing of ILSS of composite is limited to some extent and the optimum ILSS is achieved when glass-jute incorporated in composite as 50-50 weight basis. SEM images were used to study the modes of fracture, fiber-matrix adhesion, and jute-glass layer adhesion. The fracture surfaces resulted from different tests clearly show that cracks propagate throughout the polyester matrix by tearing the jute mat and delaminating the glass mat.

  8. Biofilm/Mat assays for budding yeast.

    PubMed

    Cullen, Paul J

    2015-02-02

    Many microbial species form biofilms/mats under nutrient-limiting conditions, and fungal pathogens rely on this social behavior for virulence. In budding yeast, mat formation is dependent on the mucin-like flocculin Flo11, which promotes cell-to-cell and cell-to-substrate adhesion in mats. The biofilm/mat assays described here allow the evaluation of the role of Flo11 in the formation of mats. Cells are grown on surfaces with different degrees of rigidity to assess their expansion and three-dimensional architecture, and the cells are also exposed to plastic surfaces to quantify their adherence. These assays are broadly applicable to studying biofilm/mat formation in microbial species.

  9. Bentonite mat demonstration. Final report

    SciTech Connect

    Serrato, M.G.

    1994-12-30

    The Bentonite Mat Demonstration was developed to provide the Environmental Restoration Department with field performance characteristics and engineering data for an alternative closure cover system configuration. The demonstration was initiated in response to regulatory concerns regarding the use of an alternative cover system for future design configurations. These design considerations are in lieu of the US Environmental Protection Agency (EPA) Recommended Design for Closure Cover Systems and specifically a single compacted kaolin clay layer with a hydraulic conductivity of 1 {times} 10{sup {minus}7} cm/sec. This alternative configuration is a composite geosynthetic material hydraulic barrier consisting from bottom to top: 2 ft compacted sandy clay layer (typical local Savannah River Site soil type) that is covered by a bentonite mat--geosynthetic clay liner (GCL) and is overlaid by a 40 mil High Density Polyethylene (HDPE) geomembrane--flexible membrane liner. This effort was undertaken to obtain and document the necessary field performance/engineering data for future designs and meet regulatory technical requirements for an alternative cover system configuration. The composite geosynthetic materials hydraulic barrier is the recommended alternative cover system configuration for containment of hazardous and low level radiological waste layers that have a high potential of subsidence to be used at the Savannah River Site (SRS). This alternative configuration mitigates subsidence effects in providing a flexible, lightweight cover system to maintain the integrity of the closure. The composite geosynthetic materials hydraulic barrier is recommended for the Sanitary Landfill and Low Level Radiological Waste Disposal Facility (LLRWDF) Closures.

  10. MatLab Script and Functional Programming

    NASA Technical Reports Server (NTRS)

    Shaykhian, Gholam Ali

    2007-01-01

    MatLab Script and Functional Programming: MatLab is one of the most widely used very high level programming languages for scientific and engineering computations. It is very user-friendly and needs practically no formal programming knowledge. Presented here are MatLab programming aspects and not just the MatLab commands for scientists and engineers who do not have formal programming training and also have no significant time to spare for learning programming to solve their real world problems. Specifically provided are programs for visualization. The MatLab seminar covers the functional and script programming aspect of MatLab language. Specific expectations are: a) Recognize MatLab commands, script and function. b) Create, and run a MatLab function. c) Read, recognize, and describe MatLab syntax. d) Recognize decisions, loops and matrix operators. e) Evaluate scope among multiple files, and multiple functions within a file. f) Declare, define and use scalar variables, vectors and matrices.

  11. Preparation of Sulfonated Poly(aryl ether sulfone) Electrospun Mat/Phosphosilicate Composite Proton Exchange Membrane

    NASA Astrophysics Data System (ADS)

    Wang, Limei; Dou, Liyan; Guan, Guoying

    2017-03-01

    Side-chain-type sulfonated poly(aryl ether sulfone) (SPES) was synthesized and then electrospun into mats. Phosphosilicate glass (PS) via in situ sol-gel synthesis was enclosed in the mats to form a new reinforced composite membrane. The SPES/PS composite membranes showed satisfactory dimensional change behavior with varying humidity. Especially, the composite membrane exhibits excellent proton conductivity at harsh measurement conditions of low humidity at 80°C. The composite membrane with outstanding combined properties has potential applications for high temperature polymer electrolyte membrane fuel cells.

  12. Preparation of Sulfonated Poly(aryl ether sulfone) Electrospun Mat/Phosphosilicate Composite Proton Exchange Membrane

    NASA Astrophysics Data System (ADS)

    Wang, Limei; Dou, Liyan; Guan, Guoying

    2017-01-01

    Side-chain-type sulfonated poly(aryl ether sulfone) (SPES) was synthesized and then electrospun into mats. Phosphosilicate glass (PS) via in situ sol-gel synthesis was enclosed in the mats to form a new reinforced composite membrane. The SPES/PS composite membranes showed satisfactory dimensional change behavior with varying humidity. Especially, the composite membrane exhibits excellent proton conductivity at harsh measurement conditions of low humidity at 80°C. The composite membrane with outstanding combined properties has potential applications for high temperature polymer electrolyte membrane fuel cells.

  13. Bio-optical Characteristics and the Vertical Distribution of Photosynthetic Pigments and Photosynthesis in an Artificial Cyanobacterial Mat.

    PubMed

    Kühl; Fenchel

    2000-08-01

    Zonations of photosynthesis and photopigments in artificial cyanobacterial mats were studied with (i) oxygen and pH microsensors, (ii) fiber-optic microprobes for field radiance, scalar irradiance, and PSII fluorescence, and (iii) a light microscope equipped with a spectrometer for spectral absorbance and fluorescence measurements. Our analysis revealed the presence of several distinct 1-2 mm thick cyanobacterial layers mixed with patches of anoxygenic photosynthetic bacteria. Strong attenuation of visible light confined the euphotic zone to the uppermost 3 mm of the mat, where oxygen levels of 3-4 times air saturation and a pH peak of up to pH 8.8 were observed under saturating irradiance (413 µmol photon m(-2) s(-1)). Oxygen penetration was 5 mm in light and decreased to 1 mm in darkness. Volumetric oxygen consumption in the photic and aphotic zones of illuminated mat was 5.5 and 2.9 times higher, respectively, than oxygen consumption in dark incubated mats. Scalar irradiance reached 100-150% of incident irradiance in the upper 0.5 mm of the mat due to intense scattering in the matrix of cells, exopolymers, and carbonate precipitates. In deeper mat layers scalar irradiance decreased nearly exponentially, and highest attenuation coefficients of 6-7 mm(-1) were found in cyanobacterial layers, where photosynthesis and photopigment fluorescence also peaked. Visible light was attenuated >100 times more strongly than near infrared light. Microscope spectrometry on thin sections of mats allowed detailed spectral absorbance and fluorescence measurements at defined positions relative to the mat surface. Besides strong spectral signals of cyanobacterial photopigments (Chl a and phycobiliproteins), the presence of both green and purple photosynthetic bacteria was evident from spectral signals of Bchl a and Bchl c. Microprofiles of photopigment absorbance correlated well with microdistributions of phototrophs determined in an accompanying study.

  14. Effects of mat characteristics on plantar pressure patterns and perceived mat properties during landing in gymnastics.

    PubMed

    Pérez-Soriano, Pedro; Llana-Belloch, Salvador; Morey-Klapsing, Gaspar; Perez-Turpin, Jose Antonio; Cortell-Tormo, Juan Manuel; van den Tillaar, Roland

    2010-11-01

    Shock absorption and stability during landings is provided by both, gymnast ability and mat properties. The aims of this study were to determine the influence of different mat constructions on their energy absorption and stability capabilities, and to analyse how these properties affect gymnast's plantar pressures as well as subjective mat perception during landing. Six mats were tested using a standard mechanical drop test. In addition, plantar pressures and subjective perception during landing were obtained from 15 expert gymnasts. The different mats influenced plantar pressures and gymnasts' subjective perception during landing of gymnasts. Significant correlations between plantar pressures at the medial metatarsal and lateral metatarsal zones of the gymnasts' feet with the different shock absorption characteristics of the mats were found. However, subjective perception tests were not able to discriminate mat functionality between the six mats as no significant correlations between the mechanical mat properties with the subjective perception of these properties were found. This study demonstrated that plantar pressures are a useful tool for discriminating different landing mats. Using similar approaches, ideally including kinematics as well, could help us in our understanding about the influences of different mats upon gymnast-mat interaction.

  15. Flat laminated microbial mat communities

    NASA Astrophysics Data System (ADS)

    Franks, Jonathan; Stolz, John F.

    2009-10-01

    Flat laminated microbial mats are complex microbial ecosystems that inhabit a wide range of environments (e.g., caves, iron springs, thermal springs and pools, salt marshes, hypersaline ponds and lagoons, methane and petroleum seeps, sea mounts, deep sea vents, arctic dry valleys). Their community structure is defined by physical (e.g., light quantity and quality, temperature, density and pressure) and chemical (e.g., oxygen, oxidation/reduction potential, salinity, pH, available electron acceptors and donors, chemical species) parameters as well as species interactions. The main primary producers may be photoautotrophs (e.g., cyanobacteria, purple phototrophs, green phototrophs) or chemolithoautophs (e.g., colorless sulfur oxidizing bacteria). Anaerobic phototrophy may predominate in organic rich environments that support high rates of respiration. These communities are dynamic systems exhibiting both spatial and temporal heterogeneity. They are characterized by steep gradients with microenvironments on the submillimeter scale. Diel oscillations in the physical-chemical profile (e.g., oxygen, hydrogen sulfide, pH) and species distribution are typical for phototroph-dominated communities. Flat laminated microbial mats are often sites of robust biogeochemical cycling. In addition to well-established modes of metabolism for phototrophy (oxygenic and non-oxygenic), respiration (both aerobic and anaerobic), and fermentation, novel energetic pathways have been discovered (e.g., nitrate reduction couple to the oxidation of ammonia, sulfur, or arsenite). The application of culture-independent techniques (e.g., 16S rRNA clonal libraries, metagenomics), continue to expand our understanding of species composition and metabolic functions of these complex ecosystems.

  16. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Milbourne, M.

    2005-01-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. The objective of this task is to quantify lifetimes through measurement of the optical and mechanical stability of candidate polymeric glazing and absorber materials. Polycarbonate sheet glazings, as proposed by two industry partners, have been tested for resistance to UV radiation with three complementary methods. Incorporation of a specific 2-mil thick UV-absorbing screening layer results in glazing lifetimes of at least 15 years; improved screens promise even longer lifetimes. Proposed absorber materials were tested for creep and embrittlement under high temperature, and appear adequate for planned ICS absorbers.

  17. Welding/sealing glass-enclosed space in a vacuum

    DOEpatents

    Tracy, C. Edwin; Benson, David K.

    1996-01-01

    A method of welding and sealing the edges of two juxtaposed glass sheets together to seal a vacuum space between the sheets comprises the steps of positioning a radiation absorbant material, such as FeO, VO.sub.2, or NiO, between the radiation transmissive glass sheets adjacent the edges and then irradiating the absorbant material, preferably with a laser beam, through at least one of the glass sheets. Heat produced by the absorbed radiation in the absorbant material melts glass in the portions of both glass sheets that are adjacent the absorbant material, and the melted glass from both sheets flows together to create the weld when the melted glass cools and hardens. The absorbant material can be dissolved and diffused into the melted glass to the extent that it no longer absorbs enough energy to keep the glass melted, thus, with appropriate proportioning of absorbant material to source energy power and welding heat needed, the process can be made self-stopping.

  18. Welding/sealing glass-enclosed space in a vacuum

    DOEpatents

    Tracy, C.E.; Benson, D.K.

    1996-02-06

    A method of welding and sealing the edges of two juxtaposed glass sheets together to seal a vacuum space between the sheets comprises the steps of positioning a radiation absorbent material, such as FeO, VO{sub 2}, or NiO, between the radiation transmissive glass sheets adjacent the edges and then irradiating the absorbent material, preferably with a laser beam, through at least one of the glass sheets. Heat produced by the absorbed radiation in the absorbent material melts glass in the portions of both glass sheets that are adjacent the absorbent material, and the melted glass from both sheets flows together to create the weld when the melted glass cools and hardens. The absorbent material can be dissolved and diffused into the melted glass to the extent that it no longer absorbs enough energy to keep the glass melted, thus, with appropriate proportioning of absorbent material to source energy power and welding heat needed, the process can be made self-stopping. 8 figs.

  19. Durability of Polymeric Glazing and Absorber Materials

    SciTech Connect

    Jorgensen, G.; Terwilliger, K.; Bingham, C.; Lindquist, C.; Milbourne, M.

    2005-11-01

    The Solar Heating and Lighting Program has set the goal of reducing the cost of solar water heating systems by at least 50%. An attractive approach to such large cost reduction is to replace glass and metal parts with less-expensive, lighter-weight, more-integrated polymeric components. The key challenge with polymers is to maintain performance and assure requisite durability for extended lifetimes. We have begun evaluation of several new UV-screened polycarbonate sheet glazing constructions. This has involved interactions with several major polymer industry companies to obtain improved candidate samples. Proposed absorber materials were tested for UV resistance, and appear adequate for unglazed ICS absorbers.

  20. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs.

    PubMed

    Beam, Jacob P; Bernstein, Hans C; Jay, Zackary J; Kozubal, Mark A; Jennings, Ryan deM; Tringe, Susannah G; Inskeep, William P

    2016-01-01

    Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3-3.5; temperature = 68-75°C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4-40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14-30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1-2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day(-1), and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems.

  1. Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs

    PubMed Central

    Beam, Jacob P.; Bernstein, Hans C.; Jay, Zackary J.; Kozubal, Mark A.; Jennings, Ryan deM.; Tringe, Susannah G.; Inskeep, William P.

    2016-01-01

    Biomineralized ferric oxide microbial mats are ubiquitous features on Earth, are common in hot springs of Yellowstone National Park (YNP, WY, USA), and form due to direct interaction between microbial and physicochemical processes. The overall goal of this study was to determine the contribution of different community members to the assembly and succession of acidic high-temperature Fe(III)-oxide mat ecosystems. Spatial and temporal changes in Fe(III)-oxide accretion and the abundance of relevant community members were monitored over 70 days using sterile glass microscope slides incubated in the outflow channels of two acidic geothermal springs (pH = 3–3.5; temperature = 68–75°C) in YNP. Hydrogenobaculum spp. were the most abundant taxon identified during early successional stages (4–40 days), and have been shown to oxidize arsenite, sulfide, and hydrogen coupled to oxygen reduction. Iron-oxidizing populations of Metallosphaera yellowstonensis were detected within 4 days, and reached steady-state levels within 14–30 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonized near 30 days, and emerged as the dominant functional guild after 70 days and in mature Fe(III)-oxide mats (1–2 cm thick). First-order rate constants of Fe(III)-oxide accretion ranged from 0.046 to 0.05 day−1, and in situ microelectrode measurements showed that the oxidation of Fe(II) is limited by the diffusion of O2 into the Fe(III)-oxide mat. The formation of microterracettes also implicated O2 as a major variable controlling microbial growth and subsequent mat morphology. The assembly and succession of Fe(III)-oxide mat communities follows a repeatable pattern of colonization by lithoautotrophic organisms, and the subsequent growth of diverse organoheterotrophs. The unique geochemical signatures and micromorphology of extant biomineralized Fe(III)-oxide mats are also useful for understanding other Fe(II)-oxidizing systems. PMID:26913020

  2. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    SciTech Connect

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  3. Cyanobacterial mats: Microanalysis of community metabolism

    NASA Technical Reports Server (NTRS)

    Cohen, Y.; Bermudes, D.; Fischer, U.; Haddad, R.; Prufert, L.; Scheulderman-Suylen, T.; Shaw, T.

    1985-01-01

    The microbial communities in two sites were studied using several approaches: (1) light microscopy; (2) the measurement of microprofiles of oxygen and sulfide at the surface of the microbial mat; (3) the study of diurnal variation of oxygen and sulfides; (4) in situ measurement of photosynthesis and sulfate reduction and study of the coupling of these two processes; (5) measurement of glutathione in the upper layers of the microbial mat as a possible oxygen quencher; (6) measurement of reduced iron as a possible intermediate electron donor along the established redoxcline in the mats; (7) measurement of dissolved phosphate as an indicator of processes of break down of organic matter in these systems; and (8) measurement of carbon dioxide in the interstitial water and its delta C-13 in an attempt to understand the flow of CO2 through the systems. Microbial processes of primary production and initial degradation at the most active zone of the microbial mat were analyzed.

  4. Nonwoven filtration mat production by electrospinning method

    NASA Astrophysics Data System (ADS)

    Lackowski, M.; Krupa, A.; Jaworek, A.

    2011-06-01

    The filtration of nanoparticles and submicron particles is an important problem in industry and health protection. One of the methods which can be used to solve this problem is to use nonwoven nanofibrous filters. The process of producing filtration mats of different thickness by electrospinning is presented in the paper. The experimental results on filtration properties of nanofibrous filter mat, including the efficiency of removal of cigarette smoke particles from a gas are also presented.

  5. Exploring defocus matting: nonparametric acceleration, super-resolution, and off-center matting.

    PubMed

    Joshi, Neel; Matusik, Wojciech; Avidan, Shai; Pfister, Hanspeter; Freeman, William T

    2007-01-01

    Defocus matting is a fully automatic and passive method for pulling mattes from video captured with coaxial cameras that have different depths of field and planes of focus. Nonparametric sampling can accelerate the video-matting process from minutes to seconds per frame. In addition a super-resolution technique efficiently bridges the gap between mattes from high-resolution video cameras and those from low-resolution cameras. Off-center matting pulls mattes for an external high-resolution camera that doesn't share the same center of projection as the low-resolution cameras used to capture the defocus matting data.

  6. Eukaryotes in Arctic and Antarctic cyanobacterial mats.

    PubMed

    Jungblut, Anne D; Vincent, Warwick F; Lovejoy, Connie

    2012-11-01

    Cyanobacterial mats are commonly found in freshwater ecosystems throughout the polar regions. Most mats are multilayered three-dimensional structures with the filamentous cyanobacteria embedded in a gel-like matrix. Although early descriptions mentioned the presence of larger organisms including metazoans living in the mats, there have been few studies specifically focused on the microbial eukaryotes, which are often small cells with few morphological features suitable for identification by microscopy. Here, we applied 18S rRNA gene clone library analysis to identify eukaryotes in cyanobacterial mat communities from both the Antarctic and the extreme High Arctic. We identified 39 ribotypes at the level of 99% sequence similarity. These consisted of taxa within algal and other protist groups including Chlorophyceae, Prasinophyceae, Ulvophyceae, Trebouxiophyceae, Bacillariophyceae, Chrysophyceae, Ciliophora, and Cercozoa. Fungi were also recovered, as were 21 metazoan ribotypes. The eukaryotic taxa appeared habitat-specific with little overlap between lake, pond, and ice shelf communities. Some ribotypes were common to both Arctic and Antarctic mats, suggesting global dispersal of these taxa and similarity in the environmental filters acting on protist communities. Many of these eukaryotic taxa likely benefit from protected, nutrient-rich microhabitats within the cyanobacterial mat environment.

  7. Glass sealing

    SciTech Connect

    Brow, R.K.; Kovacic, L.; Chambers, R.S.

    1996-04-01

    Hernetic glass sealing technologies developed for weapons component applications can be utilized for the design and manufacture of fuel cells. Design and processing of of a seal are optimized through an integrated approach based on glass composition research, finite element analysis, and sealing process definition. Glass sealing procedures are selected to accommodate the limits imposed by glass composition and predicted calculations.

  8. Externally tuned vibration absorber

    DOEpatents

    Vincent, Ronald J.

    1987-09-22

    A vibration absorber unit or units are mounted on the exterior housing of a hydraulic drive system of the type that is powered from a pressure wave generated, e.g., by a Stirling engine. The hydraulic drive system employs a piston which is hydraulically driven to oscillate in a direction perpendicular to the axis of the hydraulic drive system. The vibration absorbers each include a spring or other resilient member having one side affixed to the housing and another side to which an absorber mass is affixed. In a preferred embodiment, a pair of vibration absorbers is employed, each absorber being formed of a pair of leaf spring assemblies, between which the absorber mass is suspended.

  9. Shock absorber control system

    SciTech Connect

    Nakano, Y.; Ohira, M.; Ushida, M.; Miyagawa, T.; Shimodaira, T.

    1987-01-13

    A shock absorber control system is described for controlling a dampening force of a shock absorber of a vehicle comprising: setting means for setting a desired dampening force changeable within a predetermined range; drive means for driving the shock absorber to change the dampening force of the shock absorber linearly; control means for controlling the drive means in accordance with the desired dampening force when the setting of the desired dampening force has been changed; detecting means for detecting an actual dampening force of the shock absorber; and correcting means for correcting the dampening force of the shock absorber by controlling the drive means in accordance with a difference between the desired dampening force and the detected actual dampening force.

  10. CPCs with segmented absorbers

    SciTech Connect

    Keita, M.; Robertson, H.S. )

    1991-01-01

    One of the most promising means of improving the performance of solar thermal collectors is to reduce the energy lost by the hot absorber. One way to do this, not currently part of the technology, is to recognize that since the absorber is usually not irradiated uniformly, it is therefore possible to construct an absorber of thermally isolated segments, circulate the fluid in sequence from low to high irradiance segments, and reduce loss by improving effective concentration. This procedure works even for ideal concentrators, without violating Winston's theorem. Two equivalent CPC collectors with single and segmented absorber were constructed and compared under actual operating conditions. The results showed that the daily thermal efficiency of the collector with segmented absorber is higher (about 13%) than that of the collector with nonsegmented absorber.

  11. Methods for absorbing neutrons

    DOEpatents

    Guillen, Donna P [Idaho Falls, ID; Longhurst, Glen R [Idaho Falls, ID; Porter, Douglas L [Idaho Falls, ID; Parry, James R [Idaho Falls, ID

    2012-07-24

    A conduction cooled neutron absorber may include a metal matrix composite that comprises a metal having a thermal neutron cross-section of at least about 50 barns and a metal having a thermal conductivity of at least about 1 W/cmK. Apparatus for providing a neutron flux having a high fast-to-thermal neutron ratio may include a source of neutrons that produces fast neutrons and thermal neutrons. A neutron absorber positioned adjacent the neutron source absorbs at least some of the thermal neutrons so that a region adjacent the neutron absorber has a fast-to-thermal neutron ratio of at least about 15. A coolant in thermal contact with the neutron absorber removes heat from the neutron absorber.

  12. Multispectral metamaterial absorber.

    PubMed

    Grant, J; McCrindle, I J H; Li, C; Cumming, D R S

    2014-03-01

    We present the simulation, implementation, and measurement of a multispectral metamaterial absorber (MSMMA) and show that we can realize a simple absorber structure that operates in the mid-IR and terahertz (THz) bands. By embedding an IR metamaterial absorber layer into a standard THz metamaterial absorber stack, a narrowband resonance is induced at a wavelength of 4.3 μm. This resonance is in addition to the THz metamaterial absorption resonance at 109 μm (2.75 THz). We demonstrate the inherent scalability and versatility of our MSMMA by describing a second device whereby the MM-induced IR absorption peak frequency is tuned by varying the IR absorber geometry. Such a MSMMA could be coupled with a suitable sensor and formed into a focal plane array, enabling multispectral imaging.

  13. Reactive composite compositions and mat barriers

    SciTech Connect

    Langton, Christine A.; Narasimhan, Rajendran; Karraker, David G.

    2001-01-01

    A hazardous material storage area has a reactive multi-layer composite mat which lines an opening into which a reactive backfill and hazardous material are placed. A water-inhibiting cap may cover the hazardous material storage area. The reactive multi-layer composite mat has a backing onto which is placed an active layer which will neutralize or stabilize hazardous waste and a fronting layer so that the active layer is between the fronting and backing layers. The reactive backfill has a reactive agent which can stabilize or neutralize hazardous material and inhibit the movement of the hazardous material through the hazardous material storage area.

  14. Nitrogen cycle in microbial mats: completely unknown?

    NASA Astrophysics Data System (ADS)

    Coban, O.; Bebout, B.

    2015-12-01

    Microbial mats are thought to have originated around 3.7 billion years ago, most likely in the areas around submarine hydrothermal vents, which supplied a source of energy in the form of reduced chemical species from the Earth's interior. Active hydrothermal vents are also believed to exist on Jupiter's moon Europa, Saturn's moon Enceladus, and on Mars, earlier in that planet's history. Microbial mats have been an important force in the maintenance of Earth's ecosystems and the first photosynthesis was also originated there. Microbial mats are believed to exhibit most, if not all, biogeochemical processes that exist in aquatic ecosystems, due to the presence of different physiological groups of microorganisms therein. While most microbially mediated biogeochemical transformations have been shown to occur within microbial mats, the nitrogen cycle in the microbial mats has received very little study in spite of the fact that nitrogen usually limits growth in marine environments. We will present the first results in the determination of a complete nitrogen budget for a photosynthetic microbial mat. Both in situ sources and sinks of nitrogen in photosynthetic microbial mats are being measured using stable isotope techniques. Our work has a particular focus on recently described, but poorly understood, processes, e.g., anammox and dissimilatory nitrate reduction, and an emphasis on understanding the role that nitrogen cycling may play in generating biogenic nitrogen isotopic signatures and biomarker molecules. Measurements of environmental controls on nitrogen cycling should offer insight into the nature of co-evolution of these microbial communities and their planets of origin. Identifying the spatial (microscale) as well as temporal (diel and seasonal) distribution of nitrogen transformations, e.g., rates of nitrification and denitrification, within mats, particularly with respect to the distribution of photosynthetically-produced oxygen, is anticipated. The results

  15. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  16. Electromagnetic power absorber

    NASA Technical Reports Server (NTRS)

    Iwasaki, R. S. (Inventor)

    1979-01-01

    A structure is presented with a surface portion of dielectric material which passes electromagnetic radiation and with a portion below the surface which includes material that absorbs the radiation, the face of the structure being formed with numerous steep ridges. The steepness of the dielectric material results in a high proportion of the electromagnetic energy passing through the surface for absorption by the absorbing material under the surface. A backing of aluminum or other highly heat-conductive and reflective material lies under the face and has very steep protuberances supporting the absorbing and dielectric materials.

  17. Broadband infrared supercontinuum generation in a soft-glass photonic crystal fiber pumped with a sub-picosecond Er-doped fiber laser mode-locked by a graphene saturable absorber

    NASA Astrophysics Data System (ADS)

    Buczynski, Ryszard; Sobon, Grzegorz; Sotor, Jaroslaw; Klimczak, Mariusz; Stepniewski, Grzegorz; Pysz, Dariusz; Martynkien, Tadeusz; Kasztelanic, Rafal; Stepien, Ryszard; Abramski, Krzysztof M.

    2013-10-01

    A fiber-based supercontinuum source, comprising a graphene mode-locked erbium fiber laser and a highly nonlinear photonic crystal fiber (PCF), is reported. The nonlinear fiber has zero-dispersion wavelength shifted towards 1500 nm specifically for pumping with compact femtosecond and sub-picosecond fiber lasers operating in this spectral area. A chirped pulse amplification system seeded by a graphene mode-locked laser, generating linearly polarized 850 fs pulses and a pulse energy of 20 nJ at a repetition rate of 50 MHz, was used as the pump source. A 6 cm long, soft-glass PCF sample enabled generation of a supercontinuum spanning over an octave from 1000 to over 2300 nm in a 20 dB dynamic range. The measured results are interpreted numerically, based on a solution to the nonlinear Schrödinger equation using the split-step Fourier method; assignment of the nonlinear processes taking part in the observed broadening is proposed. The developed model is then used to estimate supercontinuum performance in the presented fiber with improved experimental conditions.

  18. "Smart" Electromechanical Shock Absorber

    NASA Technical Reports Server (NTRS)

    Stokes, Lebarian; Glenn, Dean C.; Carroll, Monty B.

    1989-01-01

    Shock-absorbing apparatus includes electromechanical actuator and digital feedback control circuitry rather than springs and hydraulic damping as in conventional shock absorbers. Device not subject to leakage and requires little or no maintenance. Attenuator parameters adjusted in response to sensory feedback and predictive algorithms to obtain desired damping characteristic. Device programmed to decelerate slowly approaching vehicle or other large object according to prescribed damping characteristic.

  19. Glass recycling

    SciTech Connect

    Dalmijn, W.L.; Houwelingen, J.A. van

    1995-12-31

    Glass recycling in the Netherlands has grown from 10,000 to 300,000 tonnes per annum. The various advantages and problems of the glass cycle with reference to the state of the art in the Netherlands is given. Special attention is given to new technologies for the automated sorting of cullet with detection systems. In Western Europe the recycling of glass has become a success story. Because of this, the percentage of glass cullet used in glass furnaces has increased. To meet the quality demands of the glass industry, automated sorting for the removal of stones, non-ferrous metals and other impurities had to be developed and incorporated in glass recycling plants. In Holland, Germany and other countries, the amount of glass collected has reached a level that color-sorting becomes necessary to avoid market saturation with mixed cullet. Recently, two systems for color-sorting have been developed and tested for the separation of bottles and cullet in the size range of 20--50 mm. With the increased capacity of the new glass recycling plants, 120,000--200,000 tpy, the quality systems have also to be improved and automated. These quality control systems are based on the automated sorting technology developed earlier for the glass recycling plants. The data obtained are automatically processed and printed. The sampling system and its relation to the theory of Gy will be described. Results of both developments in glass recycling plants will be described.

  20. HazMatID (trademark) Replacement Project

    DTIC Science & Technology

    2013-05-09

    uses FTIR spectroscopy. It has the capability to identify chemical warfare agents, explosives , toxic industrial chemicals, narcotics, and...off-the-shelf, Fourier transform infrared spectroscopy ( FTIR ) instruments 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...replacement for the Smiths Detection HazMatIDTM on the 886H allowance standard, a search of Fourier transform infrared spectroscopy ( FTIR ) instruments was

  1. HiMAT on lakebed after landing

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The HiMAT (Highly Maneuverable Aircraft Technology) subscale research vehicle, seen here after landing to conclude a research flight, was flown by the NASA Dryden Flight Research Center, Edwards, California, from mid 1979 to January 1983. The aircraft demonstrated advanced fighter technologies that have been used in the development of many modern high performance military aircraft. Two vehicles were used in the research program conducted jointly by NASA and the Air Force Flight Dynamics Laboratory, Wright-Patterson AFB, Ohio. The two vehicles, flown a total of 26 times, provided data on the use of composites, aeroelastic tailoring, close-coupled canards and winglets. They investigated the interaction of these then-new technologies upon each other. About one-half the size of a standard manned fighter and powered by a small jet engine, the HiMAT vehicles were launched from NASA's B-52 carrier aircraft at an altitude of about 45,000 feet. They were flown remotely by a NASA research pilot from a ground station with the aid of a television camera mounted in the HiMAT cockpits. Technologies tested on the HiMAT vehicles appearing later on other aircraft include the extensive use of composites common now on military and commercial aircraft; rear-mounted wing and forward canard configuration used very successfully on the X-29 research aircraft flown at Dryden; and winglets, now used on many private and commercial aircraft to lessen wingtip drag and enhance fuel savings.

  2. Glass Artworks

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Several NASA technologies have played part in growth and cost containment of studio glass art, among them a foam type insulation developed to meet a need for lightweight material that would reduce flame spread in aircraft fire. Foam comes in several forms and is widely used by glass artists, chiefly as an insulator for the various types of ovens used in glass working. Another Spinoff is alumina crucibles to contain molten glass. Before alumina crucibles were used, glass tanks were made of firebrick which tended to erode under high temperatures and cause impurities; this not only improved quality but made the process more cost effective. One more NASA technology that found its way into glass art working is a material known as graphite board, a special form of graphite originally developed for rocket motor applications. This graphite is used to exact compound angles and creates molds for poured glass artworks of dramatic design.

  3. Glass heat pipe evacuated tube solar collector

    DOEpatents

    McConnell, Robert D.; Vansant, James H.

    1984-01-01

    A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

  4. Glass heat pipe evacuated tube solar collector

    SciTech Connect

    McConnell, R.D.; Vansant, J.H.

    1984-10-02

    A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

  5. Prominent reinforcing effect of chitin nanocrystals on electrospun polydioxanone nanocomposite fiber mats.

    PubMed

    Zhu, Lei; Liang, Kai; Ji, Yali

    2015-04-01

    The ultra-strong nanocomposite fiber mats based on biodegradable polydioxanone (PDO) and chitin nanocrystals (ChiNCs) were successfully prepared by means of electrospinning. The ChiNCs are uniformly dispersed in the PDO matrix and mostly oriented along fiber long axis, resulting in a significant improvement in mechanical property. Moreover, the introduction of ChiNCs led to the increase of the glass-transition temperature (Tg) and thermal decomposition temperature (Td) of PDO elucidated by thermal analyses. In addition, the loading of ChiNCs caused very different In vitro degradation behavior compared to neat PDO fiber mat. Furthermore, in vitro cell culture results indicated that the addition of ChiNCs improved the cellular adhesion and proliferation.

  6. Evaluation of Degradation of Ceramic Fiber Mat by Acoustic Emission

    SciTech Connect

    Ito, Kaita; Enoki, Manabu; Takahashi, Hidetomo

    2005-04-09

    Alumina-silica fiber mat is widely used as thermal insulator because of its good stability under high temperature environment. However, this material degrades gradually during long-term use under pressure and elevated temperature. In this study, cyclic compression tests of the mat were conducted and monitored acoustic emission (AE) of the mat both at room temperature and elevated temperature. The degradation of mat was evaluated by AE parameters.

  7. Method for production of carbon nanofiber mat or carbon paper

    DOEpatents

    Naskar, Amit K.

    2015-08-04

    Method for the preparation of a non-woven mat or paper made of carbon fibers, the method comprising carbonizing a non-woven mat or paper preform (precursor) comprised of a plurality of bonded sulfonated polyolefin fibers to produce said non-woven mat or paper made of carbon fibers. The preforms and resulting non-woven mat or paper made of carbon fiber, as well as articles and devices containing them, and methods for their use, are also described.

  8. Evaluation of Degradation of Ceramic Fiber Mat by Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Ito, Kaita; Enoki, Manabu; Takahashi, Hidetomo

    2005-04-01

    Alumina-silica fiber mat is widely used as thermal insulator because of its good stability under high temperature environment. However, this material degrades gradually during long-term use under pressure and elevated temperature. In this study, cyclic compression tests of the mat were conducted and monitored acoustic emission (AE) of the mat both at room temperature and elevated temperature. The degradation of mat was evaluated by AE parameters.

  9. Glass Research

    NASA Technical Reports Server (NTRS)

    Weinberg, M. C.

    1985-01-01

    Research efforts span three general areas of glass science: glass refining, gel-derived glasses, and nucleation and crystallization of glasses. Gas bubbles which are present in a glass product are defects which may render the glass totally useless for the end application. For example, optical glasses, laser host glasses, and a variety of other specialty glasses must be prepared virtually defect free to be employable. Since a major mechanism of bubble removal, buoyant rise, is virtually inoperative in microgravity, glass fining will be especially difficult in space. On the other hand, the suppression of buoyant rise and the ability to perform containerless melting experiments in space allows the opportunity to carry out several unique bubble experiments in space. Gas bubble dissolution studies may be performed at elevated temperatures for large bubbles with negligible bubble motion. Also, bubble nucleation studies may be performed without the disturbing feature of heterogeneous bubble nucleation at the platinum walls. Ground based research efforts are being performed in support of these potential flight experiments.

  10. Characterization and Modification of Electrospun Fiber Mats for Use in Composite Proton Exchange Membranes

    NASA Astrophysics Data System (ADS)

    Mannarino, Matthew Marchand

    . Post-spin thermal annealing was used to modify the fiber morphology, inter-fiber welding, and crystallinity within the fibers. Morphological changes, in-plane tensile response, friction coefficient, and wear rate were characterized as functions of the annealing temperature. The Young's moduli, yield stresses and toughnesses of the PA 6(3)T nonwoven mats improved by two- to ten-fold when annealed slightly above the glass transition temperature, but at the expense of mat porosity. The mechanical and tribological properties of the thermally annealed P A 6,6 fiber mats exhibited significant improvements through the Brill transition temperature, comparable to the improvements observed for amorphous P A 6(3)T electrospun mats annealed near the glass transition temperature. The wear rates for both polymer systems correlate with the yield properties of the mat, in accordance with a modified Ratner-Lancaster model. The variation in mechanical and tribological properties of the mats with increasing annealing temperature is consistent with the formation of fiber-to-fiber junctions and a mechanism of abrasive wear that involves the breakage of these junctions between fibers. A mechanically robust proton exchange membrane with high ionic conductivity and selectivity is an important component in many electrochemical energy devices such as fuel cells, batteries, and photovoltaics. The ability to control and improve independently the mechanical response, ionic conductivity, and selectivity properties of a membrane is highly desirable in the development of next generation electrochemical devices. In this thesis, the use of layer-by-layer (LbL) assembly of polyelectrolytes is used to generate three different polymer film morphologies on highly porous electrospun fiber mats: webbed, conformal coating, and pore-bridging films. Specifically, depending on whether a vacuum is applied to the backside of the mat or not, the spray-LbL assembly either fills the voids of the mat with the proton

  11. Unidirectional perfect absorber

    PubMed Central

    Jin, L.; Wang, P.; Song, Z.

    2016-01-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices. PMID:27615125

  12. Shock absorber servicing tool

    NASA Technical Reports Server (NTRS)

    Koepler, Jack L. (Inventor); Hill, Robert L. (Inventor)

    1981-01-01

    A tool to assist in the servicing of a shock absorber wherein the shock absorber is constructed of a pair of aligned gas and liquid filled chambers. Each of the chambers is separated by a movable separator member. Maximum efficiency of the shock absorber is achieved in the locating of a precise volume of gas within the gas chamber and a precise volume of liquid within the liquid chamber. The servicing tool of this invention employs a rod which is to connect with the separator and by observation of the position of the rod with respect to the gauge body, the location of the separator is ascertained even though it is not directly observable.

  13. Unidirectional perfect absorber

    NASA Astrophysics Data System (ADS)

    Jin, L.; Wang, P.; Song, Z.

    2016-09-01

    This study proposes a unidirectional perfect absorber (UPA), which we realized with a two-arm Aharonov-Bohm interferometer, that consists of a dissipative resonator side-coupled to a uniform resonator array. The UPA has reflection-less full absorption on one direction, and reflectionless full transmission on the other, with an appropriate magnetic flux and coupling, detuning, and loss of the side-coupled resonator. The magnetic flux controls the transmission, the left transmission is larger for magnetic flux less than one-half flux quantum; and the right transmission is larger for magnetic flux between one-half and one flux quantum. Besides, a perfect absorber (PA) can be realized based on the UPA, in which light waves from both sides, with arbitrary superposition of the ampli- tude and phase, are perfectly absorbed. The UPA is expected to be useful in the design of novel optical devices.

  14. Ecophysiological Changes in Microbial Mats Incubated in a Greenhouse Collaboratory

    NASA Technical Reports Server (NTRS)

    Bebout, Brad; DesMarais, David J.; GarciaPichel, Ferran; Hogan, Mary; Jahnke, Linda; Keller, Richard M.; Miller, Scott R.

    2001-01-01

    Microbial mats are modern examples of the earliest microbial communities known. Among the best studied are microbial mats growing in hypersaline ponds managed for the production of salt by Exportadora de Sal, S.A. de C.V., Guerrero Negro, Baja California Sur, Mexico. In May, 2001, we collected mats from Ponds 4 and 5 in this system and returned them to Ames Research Center, where they have been maintained for a period of over nine months. We report here on both the ecophysiological changes occurring in the mats over that period of time as well as the facility in which they were incubated. Mats (approximately 1 sq. meter total area) were incubated in a greenhouse facility modified to provide the mats with natural levels of visible and ultraviolet radiation as well as constantly flowing, temperature-controlled water. Two replicated treatments were maintained, a 'high salinity' treatment (about 120 ppt) and a 'low salinity' treatment (about 90 ppt). Rates of net biological activity (e.g., photosynthesis, respiration, trace gas production) in the mats were relatively constant over the several months, and were similar to rates of activity measured in the field. However, over the course of the incubation, mats in both treatments changed in physical appearance. The most obvious change was that mats in the higher salinity treatments developed a higher proportion of carotenoid pigments (relative to chlorophyll), resulting in a noticeably orange color in the high salinity mats. This trend is also seen in the natural salinity gradient present at the field site. Changes in the community composition of the mats, as assayed by denaturing gradient gel electrophoresis (DGGE), as well as biomarker compounds produced in the mats were also monitored. The degree to which the mats kept in the greenhouse changed from the originally collected mats, as well as differences between high and low salinity mats will be discussed. Additional information is contained in the original extended

  15. Shock Absorbing System

    NASA Astrophysics Data System (ADS)

    1982-01-01

    A lightweight, inexpensive shock-absorbing system, developed by Langley Research Center 20 years ago, is now in service as safety device for an automated railway at Duke University Medical Center. The transportation system travels at about 25 miles per hour, carrying patients, visitors, staff and cargo. At the end of each guideway of the system are "frangible," (breakable) tube "buffers." If a slowing car fails to make a complete stop at the terminal, it would bump and shatter the tubes, absorbing energy that might otherwise jolt the passengers or damage the vehicle.

  16. ChemMatCARS Data Archive

    DOE Data Explorer

    ChemMatCARS is a high-brilliance national synchrotron x-ray facility dedicated primarily to static and dynamic condensed matter chemistry and materials science. The scientific focus of the facility includes the study of surface and interfacial properties of liquids and solids as well as their bulk structure at atomic, molecular and mesoscopic length scales with high spatial and energy resolution. Experimental techniques supported by the facility include: 1) Liquid Surface X-ray Scattering; 2) Solid Surface X-ray Scattering; 3) Time-Resolved Crystallography; 4) Micro-Crystal Diffraction; 5) Small and Wide-angle X-ray Scattering. The data archive referenced here contains data for various components along the beamline within the First Optics Enclosure and is intended to be input or parameter data. See the Science Nuggets at http://cars9.uchicago.edu/chemmat/pages/nuggets.html for leads to some of the research conducted at the ChemMatCARS beamline.

  17. Microbial mats: an ecological niche for fungi

    PubMed Central

    Cantrell, Sharon A.; Duval-Pérez, Lisabeth

    2013-01-01

    Fungi were documented in tropical hypersaline microbial mats and their role in the degradation of complex carbohydrates (exopolymeric substance – EPS) was explored. Fungal diversity is higher during the wet season with Acremonium, Aspergillus, Cladosporium, and Penicillium among the more common genera. Diversity is also higher in the oxic layer and in young and transient mats. Enrichments with xanthan (a model EPS) show that without antibiotics (full community) degradation is faster than enrichments with antibacterial (fungal community) and antifungal (bacterial community) agents, suggesting that degradation is performed by a consortium of organisms (bacteria and fungi). The combined evidence from all experiments indicates that bacteria carried out approximately two-third of the xanthan degradation. The pattern of degradation is similar between seasons and layers but degradation is faster in enrichments from the wet season. The research suggests that fungi thrive in these hypersaline consortia and may participate in the carbon cycle through the degradation of complex carbohydrates. PMID:23577004

  18. Bioflumology: Microbial mat growth in flumes

    NASA Astrophysics Data System (ADS)

    Airo, A.; Weigert, S.; Beck, C.

    2014-04-01

    The emergence of oxygenic photosynthesis resulted in a transformational change of Earth's geochemical cycles and the subsequent evolution of life. However, it remains vigorously debated when this metabolic ability had evolved in cyanobacteria. This is largely because studies of Archean microfossil morphology, molecular biomarkers, and isotopic characteristics are frequently ambiguous. However, the high degree of morphological similarities between modern photosynthetic and Archean fossil mats has been interpreted to indicate phototactic microbial behavior or oxygenic photosynthesis. In order to better evaluate the relationship between mat morphology and metabolism, we here present a laboratory set-up for conducting month-long experiments in several sterilizable circular flumes designed to allow single-species cyanobacterial growth under adjustable fluid-flow conditions and protected from contamination.

  19. Astronaut Thomas Mattingly performs EVA during Apollo 16 transearth coast

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut Thomas K. Mattingly II, command module pilot of the Apollo 16 lunar landing mission, performs extravehicular activity (EVA) during the Apollo 16 transearth coast. mattingly is assisted by Astronaut Charles M. Duke Jr., lunar module pilot. Mattingly inspected the SIM bay of the Service Module, and retrieved film from the Mapping and Panoramic cameras. Mattingly is wearing the helmet of Astronaut John W. Young, commander. The helmet's lunar extravehicular visor assembly helped protect Mattingly's eyes frmo the bright sun. This view is a frame from motion picture film exposed by a 16mm Maurer camera.

  20. Lava Cave Microbial Communities Within Mats and Secondary Mineral Deposits: Implications for Life Detection on Other Planets

    PubMed Central

    Melim, L.A.; Spilde, M.N.; Hathaway, J.J.M.; Garcia, M.G.; Moya, M.; Stone, F.D.; Boston, P.J.; Dapkevicius, M.L.N.E.; Riquelme, C.

    2011-01-01

    Abstract Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai‘i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai‘i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai‘i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies. Key Words: Biosignatures—Astrobiology—Bacteria—Caves—Life detection—Microbial mats. Astrobiology 11, 601–618. PMID:21879833

  1. Chemical compatibility study of Cooley L18KU, Herculite, and Elephant Mat with Hanford tank waste

    SciTech Connect

    Mercado, J.E.

    1998-06-23

    An independent chemical compatibility review of various wrapping and absorbent/padding materials was conducted to evaluate resistance to chemicals and constituents present in liquid waste from the Hanford underground tanks. These materials will be used to wrap long-length contaminated equipment when such equipment is removed from the tanks and prepared for transportation and subsequent disposal or storage. The materials studied were Cooley L18KU, Herculite, and Elephant Mat. The study concludes that these materials are appropriate for use in this application.

  2. A Theoretical Study of Landing Mat Behavior

    DTIC Science & Technology

    1969-07-01

    the end joint expcrience6 progressive eeteriora- tion uc ’-o - con:r ;itaticn oL mat breaks ( rivet filure, cracking, an. curling) [l21. The weakened...Establishment, Suffield s-69-4 Oct 1969 Dutch Friction -Cone Penetrometer Exploration of Research Area at Field 5, Eglin APB, Florida *S-69-5 Apr 1969 Cracking...Tests. 66 12. Comparison of Performance for Single- Wheel Tests . . . . . . . . .. . 67 13. End Joint Moment Transfer Deficiency Based Upon Uniform

  3. Solar concentrator/absorber

    NASA Technical Reports Server (NTRS)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  4. Neutron Absorbing Alloys

    SciTech Connect

    Mizia, Ronald E.; Shaber, Eric L.; DuPont, John N.; Robino, Charles V.; Williams, David B.

    2004-05-04

    The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

  5. Shock Absorbing Helmets

    NASA Technical Reports Server (NTRS)

    1978-01-01

    This paper presents a description of helmets used by football players that offer three times the shock-absorbing capacity of earlier types. An interior padding for the helmets, composed of Temper Foam, first used by NASA's Ames Research Center in the design of aircraft seats is described.

  6. Composite polymer-glass edge cladding for laser disks

    DOEpatents

    Powell, Howard T.; Riley, Michael O.; Wolfe, Charles R.; Lyon, Richard E.; Campbell, John H.; Jessop, Edward S.; Murray, James E.

    1989-01-01

    Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation.

  7. Composite polymer: Glass edge cladding for laser disks

    DOEpatents

    Powell, H.T.; Wolfe, C.A.; Campbell, J.H.; Murray, J.E.; Riley, M.O.; Lyon, R.E.; Jessop, E.S.

    1987-11-02

    Large neodymium glass laser disks for disk amplifiers such as those used in the Nova laser require an edge cladding which absorbs at 1 micrometer. This cladding prevents edge reflections from causing parasitic oscillations which would otherwise deplete the gain. Nova now utilizes volume-absorbing monolithic-glass claddings which are fused at high temperature to the disks. These perform quite well but are expensive to produce. Absorbing glass strips are adhesively bonded to the edges of polygonal disks using a bonding agent whose index of refraction matches that of both the laser and absorbing glass. Optical finishing occurs after the strips are attached. Laser disks constructed with such claddings have shown identical gain performance to the previous Nova disks and have been tested for hundreds of shots without significant degradation. 18 figs.

  8. Durability-Based Design Criteria for a Chopped-Glass-Fiber Automotive Structural Composite

    SciTech Connect

    Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

    1999-11-01

    This report provides recommended durability-based design criteria for a chopped-glass-fiber reinforced polymeric composite for automotive structural applications. The criteria closely follow the framework of an earlier criteria document for a continuous-strand-mat (CSM) glass-fiber reference composite. Together these design criteria demonstrate a framework that can be adapted for future random-glass-fiber composites for automotive structural applications.

  9. Metasurface Broadband Solar Absorber

    PubMed Central

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-01-01

    We demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure. PMID:26828999

  10. Metasurface Broadband Solar Absorber

    DOE PAGES

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; ...

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributionsmore » to elucidate how the absorption occurs within the metasurface structure.« less

  11. Metasurface Broadband Solar Absorber

    SciTech Connect

    Azad, Abul K.; Kort-Kamp, Wilton J. M.; Sykora, Milan; Weisse-Bernstein, Nina R.; Luk, Ting S.; Taylor, Antoinette J.; Dalvit, Diego A. R.; Chen, Hou-Tong

    2016-02-01

    Here, we demonstrate a broadband, polarization independent, wide-angle absorber based on a metallic metasurface architecture, which accomplishes greater than 90% absorptance in the visible and near-infrared range of the solar spectrum, and exhibits low absorptivity (emissivity) at mid- and far-infrared wavelengths. The complex unit cell of the metasurface solar absorber consists of eight pairs of gold nano-resonators that are separated from a gold ground plane by a thin silicon dioxide spacer. Moreover, our experimental measurements reveal high-performance absorption over a wide range of incidence angles for both s- and p-polarizations. We also investigate numerically the frequency-dependent field and current distributions to elucidate how the absorption occurs within the metasurface structure.

  12. GLASS FIBER REINFORCED PLASTICS,

    DTIC Science & Technology

    Contents: Fibrous glass fillers Binders used in the glass plastic industry Method of manufacturing glass plastics and glass plastic articles Properties of fiberglass Primary areas for use of glass fibre reinforced plastics

  13. Ionized Absorbers in AGN

    NASA Technical Reports Server (NTRS)

    Mathur, S.

    1999-01-01

    As a part of this program, we observed three AGN:PKS2251 + 113, PG0043 = 039 and PLH909. Two objects show signatures of absorbtion in their UV spectra. Based on our earlier modeling of X-ray warm absorbents, we expected to observe X-ray observation in these objects. The third, PLH909, is known to have soft excess in EINSTEIN data. Attachment: "Exploratory ASCA observation of broad absorption line quasi-stellar objects".

  14. Apollo couch energy absorbers

    NASA Technical Reports Server (NTRS)

    Wesselski, C. J.; Drexel, R. E.

    1972-01-01

    Load attenuators for the Apollo spacecraft crew couch and its potential applications are described. Energy absorption is achieved through friction and cyclic deformation of material. In one concept, energy absorption is accomplished by rolling a compressed ring of metal between two surfaces. In another concept, energy is absorbed by forcing a plastically deformed washer along a rod. Among the design problems that had to be solved were material selection, fatigue life, ring slippage, lubrication, and friction loading.

  15. Flow-induced Development of Unicellular Cyanobacterial Mats

    NASA Astrophysics Data System (ADS)

    Gong, J.; Tice, M. M.

    2011-12-01

    Microbial mats/biofilms are abundant microbial growth structures throughout the history of life on Earth. Understanding the mechanisms for their morphogenesis and interactions with physical sedimentary forces are important topics that allow deeper understanding of related records. When subjected to hydrodynamic influences, mats are known to vary in morphology and structure in response to fluid shear, yet mechanistically, the underlying cellular architecture due to interactions with flow remain unexplained. Moreover, mats are found to emerge larger scale roughness elements and modified cohesive strength growing under flow. It is a mystery how and why these mat-community-level features are linked in association with modified boundary layers at the mats surface. We examined unicellular cyanobacterium Synechocystis sp. PCC 6803 in a circular flow bioreactor designed to maintain a fixed set of hydrodynamic conditions. The use of monoculture strains and unidirectional currents, while not replicating natural mat systems (almost certainly multi-species and often multi-directional currents under complex wind or tidal wave actions), helps to simplify these systems and allows for specific testing of hypotheses regarding how mats evolve distinctive morphologies induced by flow. The unique design of the reactor also makes measurements such as critical erosional shear stress of the mats possible, in addition to microscopic, macroscopic imaging and weeks of continuous mats growth monitoring. We report the finding that linear chains, filament-like cell groups were present from unicellular cyanobacterial mats growing under flow (~1-5 cm/s) and these structures are organized within ~1-3mm size streamers and ~0.5-1mm size nodular macrostructures. Ultra-small, sub-micron thick EPS strings are observed under TEM and are likely the cohesive architectural elements in mats across different fluid regimes. Mat cohesion generally grows with and adapts to increasing flow shear stress within

  16. Tempered glass

    SciTech Connect

    Bunnell, L.R.

    1991-11-01

    This document describes a demonstration for making tempered glass using minimal equipment. The demonstration is intended for a typical student of materials science, at the high school level or above. (JL)

  17. Differential microbial communities in hot spring mats from Western Thailand.

    PubMed

    Portillo, M C; Sririn, V; Kanoksilapatham, W; Gonzalez, J M

    2009-03-01

    The microbial communities of freshwater hot spring mats from Boekleung (Western Thailand) were studied. Temperatures ranged from over 50 up to 57 degrees C. Green-, red-, and yellow colored mat layers were analyzed. In order to detect the major components of the microbial communities constituting the mat as well as the microorganisms showing significant metabolic activity, samples were analyzed using DNA- and RNA-based molecular techniques, respectively. Microbial community fingerprints, performed by denaturing gradient gel electrophoresis (DGGE), revealed clear differences among mat layers. Thermophilic phototrophic microorganisms, Cyanobacteria and Chloroflexi, constituted the major groups in these communities (on average 65 and 51% from DNA and RNA analyses, respectively). Other bacteria detected in the mat were Bacteroidetes, members of the Candidate Division OP10, Actinobacteria, and Planctomycetes. Differently colored mat layers showed characteristic bacterial communities and the major components of the metabolically active fraction of these communities have been identified.

  18. Pressure Sensitive Mats as Safety Devices in Danger Zones.

    PubMed

    Dąbrowski, Stanisław; Brański, Zygfryd

    1998-01-01

    Developing prototypes of pressure sensitive mats and testing their practical application were the aims of this study. Two contact plate mats were designed and constructed: rubber-rubber (R) and metal-metal (M). A recipe for rubber mixes and the production technology were prepared. Two laboratory test stands for measuring the actuating force, response time, static pressure resistance, and the durability of the mats were constructed. Computer software was written to control the operation of those test stands. Methods of testing pressure sensitive mats were based on PrDIN 31 006 (Deutsches Institut fur Normung [DIN], 1990) and EN 1760-1 (Comite Europeen de Normalisation [CEN], 1997). Both prototypes of contact plate mats were tested under laboratory and industrial conditions. The test results proved that the design was correct, the setup requirements were fulfilled, and the mats were efficient and reliable in the industrial environment.

  19. Absorber for terahertz radiation management

    SciTech Connect

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.

    2015-12-08

    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  20. Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona

    NASA Astrophysics Data System (ADS)

    Fayek, Mostafa; Anovitz, Lawrence M.; Allard, Lawrence F.; Hull, Sharon

    2012-02-01

    At the end of the Pleistocene a Younger Dryas "black mat" was deposited on top of the Pleistocene sediments in many parts of North America. A study of the magnetic fraction (~ 10,900 ± 50 B.P.) from the basal section of the black mat at Murray Springs, AZ revealed the presence of amorphous iron oxide framboids in a glassy iron-silica matrix. These framboids are very similar in appearance and chemistry to those reported from several types of carbonaceous chondrites. The glass contains iron, silicon, oxygen, vanadium and minor titanium, while the framboidal particles contain calcium as well. The major element chemistry of both the spherules and the glass matrix are consistent with the chemistry of material associated with meteorite impact sites and meteorites. Electron microscopy confirms that the glassy material is indeed amorphous, and also shows that what appear to be individual oxide particles are amorphous as well. The latter appears consistent with their overall morphology that, while euhedral, typically shows significant fracture. Based on these data, we argue that these particles are the product of a hypervelocity impact.

  1. Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona

    SciTech Connect

    Fayek, Mostafa; Anovitz, Lawrence {Larry} M; Allard Jr, Lawrence Frederick; Hull, Sharon

    2011-01-01

    At the end of the Pleistocene a Younger Dryas black mat was deposited on top of the Pleistocene sediments inmany parts of North America. A study of themagnetic fraction ({approx}10,900 50 B.P.) fromthe basal section of the black mat at Murray Springs, AZ revealed the presence of amorphous iron oxide framboids in a glassy iron-silica matrix. These framboids are very similar in appearance and chemistry to those reported from several types of carbonaceous chondrites. The glass contains iron, silicon, oxygen, vanadium and minor titanium, while the framboidal particles contain calcium as well. The major element chemistry of both the spherules and the glass matrix are consistent with the chemistry of material associated with meteorite impact sites and meteorites. Electron microscopy confirms that the glassy material is indeed amorphous, and also shows that what appear to be individual oxide particles are amorphous as well. The latter appears consistent with their overall morphology that, while euhedral, typically shows significant fracture. Based on these data, we argue that these particles are the product of a hypervelocity impact.

  2. Framboidal iron oxide: Chondrite-like material from the black mat, Murray Springs, Arizona

    SciTech Connect

    Fayek, Mostafa; Anovitz, Lawrence {Larry} M; Allard Jr, Lawrence Frederick; Hull, Sharon

    2012-01-01

    At the end of the Pleistocene a Younger Dryas black mat was deposited on top of the Pleistocene sediments in many parts of North America. A study of the magnetic fraction (~10,900 50 B.P.) from the basal section of the black mat at Murray Springs, AZ revealed the presence of amorphous iron xide framboids in a glassy iron-silica matrix. These framboids are very similar in appearance and chemistry to those reported from several types of carbonaceous chondrites. The glass contains iron, silicon, oxygen, vanadium and minor titanium, while the framboidal particles contain calcium as well. The major element chemistry of both the spherules and the glass matrix are consistent with the chemistry of material associated with meteorite impact sites and meteorites. Electron microscopy confirms that the glassy material is indeed amorphous, and also shows that what appear to be individual oxide particles are amorphous as well. The latter appears consistent with their overall morphology that, while euhedral, typically shows significant fracture. Based on these data, we argue that these particles are the product of a hypervelocity impact.

  3. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan [El Cerrito, CA; Farmer, Joseph C [Tracy, CA; Lee, Chuck K [Hayward, CA; Walker, Jeffrey [Gaithersburg, MD; Russell, Paige [Las Vegas, NV; Kirkwood, Jon [Saint Leonard, MD; Yang, Nancy [Lafayette, CA; Champagne, Victor [Oxford, PA

    2012-05-29

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  4. Corrosion resistant neutron absorbing coatings

    DOEpatents

    Choi, Jor-Shan; Farmer, Joseph C; Lee, Chuck K; Walker, Jeffrey; Russell, Paige; Kirkwood, Jon; Yang, Nancy; Champagne, Victor

    2013-11-12

    A method of forming a corrosion resistant neutron absorbing coating comprising the steps of spray or deposition or sputtering or welding processing to form a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material. Also a corrosion resistant neutron absorbing coating comprising a composite material made of a spray or deposition or sputtering or welding material, and a neutron absorbing material.

  5. Allelopathy-mediated Competition in Microbial Mats from Antarctic Lakes.

    PubMed

    Slattery, Marc; Lesser, Michael P

    2017-02-18

    Microbial mats are vertically stratified communities that host a complex consortium of microorganisms, dominated by cyanobacteria, that compete for available nutrients and environmental niches, within these extreme habitats. The Antarctic Dry Valleys near McMurdo Sound include a series of lakes within the drainage basin that are bisected by glacial traverses. These lakes are traditionally independent, but recent increases in glacial melting have allowed two lakes (Chad and Hoare) to become connected by a meltwater stream. Microbial mats were collected from these lakes, and cultured under identical conditions at the McMurdo Station laboratory. Replicate pairings of the microbial mats exhibited consistent patterns of growth inhibition indicative of competitive dominance. Natural products were extracted from the microbial mats, and a disc diffusion assay was utilized to show that allelochemical compounds mediate competitive interactions. Both microscopy and 16S rRNA sequencing show that these mats contain significant populations of cyanobacteria known to produce allelochemicals. Two compounds were isolated from these microbial mats that might be important in the chemical ecology of these psychrophiles. In other disc:mat pairings, including extract versus mat of origin, the allelochemicals exhibited no effect. Taken together, these results indicate that Antarctic lake microbial mats can compete via allelopathy.

  6. Reduced Gas Cycling in Microbial Mats: Implications for Early Earth

    NASA Technical Reports Server (NTRS)

    Hoehler, Tori M.; Bebout, Brad M.; DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    For more than half the history of life on Earth, biological productivity was dominated by photosynthetic microbial mats. During this time, mats served as the preeminent biological influence on earth's surface and atmospheric chemistry and also as the primary crucible for microbial evolution. We find that modern analogs of these ancient mat communities generate substantial quantities of hydrogen, carbon monoxide, and methane. Escape of these gases from the biosphere would contribute strongly to atmospheric evolution and potentially to the net oxidation of earth's surface; sequestration within the biosphere carries equally important implications for the structure, function, and evolution of anaerobic microbial communities within the context of mat biology.

  7. Bioremediation of metals, organic and mixed contaminants with microbial mats

    SciTech Connect

    Bender, J.

    1995-12-31

    Microbial mats are natural heterotrophic and autotrophic communities dominated by cyanobacteria (blue-green algae). They are self-organized laminated structures annealed tightly together by slimy secretions from various microbial components. The surface slime of the mats effectively immobilizes the ecosystem to a variety of substrates, thereby stabilizing the most efficient internal microbial structure. Cyanobacteria mats are generated for bioremediation applications by enriching a water surface with ensiled grass clippings. These constructed mats have been used to reduce selenate to elemental selenium, remove Pb, Cd, Cu, Zn, Co, Cr, Fe and Mn from water and to remove Pb from sediments of shallow laboratory ponds. Uranium, U{sup 238}, was removed from groundwater samples at the rate of 3.19 Mg/m{sup 2}/h. Degradation of recalcitrant organic contaminants by mats is relatively rapid under both dark and light conditions. The following contaminants have been degraded in water and/or soil media by constructed mats: TNT, chrysene, naphthalene, hexadecane, phenanthrene, PCB, TCE, pulp and paper mill wastes, and three pesticides: chlordane, carbofuran and paraquat. Radio-labeled experiments with mat-treated carbofuran, petroleum distillates, TNT, chlordane, PCB and TCE show that these compounds are mineralized by the constructed mats. Mats applied to mixed contaminant solutions (TCE + Zn and TNT + pb) sequestered the metal while mineralizing the TCE. Remediation rates of the organic and inorganic components were the same in mixed solution as they were in single application.

  8. Solar radiation absorbing material

    DOEpatents

    Googin, John M.; Schmitt, Charles R.; Schreyer, James M.; Whitehead, Harlan D.

    1977-01-01

    Solar energy absorbing means in solar collectors are provided by a solar selective carbon surface. A solar selective carbon surface is a microporous carbon surface having pores within the range of 0.2 to 2 micrometers. Such a surface is provided in a microporous carbon article by controlling the pore size. A thermally conductive substrate is provided with a solar selective surface by adhering an array of carbon particles in a suitable binder to the substrate, a majority of said particles having diameters within the range of about 0.2-10 microns.

  9. Stromatolites, Metals, Statistics and Microbial Mats: A Complex Interplay

    NASA Astrophysics Data System (ADS)

    Spear, J. R.

    2014-12-01

    Initially thought to be relatively 'simple' ecosystems for study, microbial mats have long been considered ideal for any number of research questions. Microbial mats can be found in any number of environments, both natural and manmade, and are typically dependent upon the physiochemical environment for their structure, maintenance and longevity. Ultimately, these and other parameters govern community whereby a microbial mat provides overall ecosystem services to their environment. On the edge of a hotspring in Yellowstone National Park we have found an active microbial mat community that can form a laminated, lithified, accretionary structure that is likely the best example of a living and growing stromatolite. In the outfall channel of the sulfidic Stinking Spring, Utah, we have found examples of both naturally occurring laminated and floating mats where the carbon flux is controlled by abiotic degassing of CO2 rather than metabolism. δ13C-bicarbonate uptake experiments reveal an autotrophic growth rate of 0 - 0.16%/day while δ13C-acetate reveals a higher heterotrophic growth rate of 0.03 - 0.65%/day, which highlights the role of heterotrophs in these mats. Similar growth experiments on Little Hot Creek, California laminated microbial mats reveal a trend for top-down microbial growth with similar microbial taxonomy and diversity to other mat-types. Of a curious note is that incubation experiments with Little Hot Creek mats reveals the importance of particular metals in mat structure and function. Statistically, alpha- and beta-diversity metrics are often used to characterize microbial communities in such systems, but from an analysis of a wastewater treatment system, Hill diversities can better interpret the effective number of species to produce an ecologically intuitive quantity to better understand a microbial mat ecosystem.

  10. Method of producing a ceramic fiber-reinforced glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1994-01-01

    A fiber-reinforced composite composed of a BaO-Al2O3-2SiO2 (BAS) glass ceramic matrix is reinforced with CVD silicon carbide continuous fibers. A slurry of BAS glass powders is prepared and celsian seeds are added during ball melting. The slurry is cast into tapes which are cut to the proper size. Continuous CVD-SiC fibers are formed into mats of the desired size. The matrix tapes and the fiber mats are alternately stacked in the proper orientation. This tape-mat stack is warm pressed to produce a 'green' composite. The 'green' composite is then heated to an elevated temperature to burn out organic constituents. The remaining interim material is then hot pressed to form a silicon carbide fiber-reinforced celsian (BAS) glass-ceramic matrix composite which may be machined to size.

  11. Liquid Cryogen Absorber for MICE

    SciTech Connect

    Baynham, D.E.; Bish, P.; Bradshaw, T.W.; Cummings, M.A.; Green,M.A.; Ishimoto, S.; Ivaniouchenkov, I.; Lau, W.; Yang, S.Q.; Zisman, M.S.

    2005-08-20

    The Muon Ionization Cooling Experiment (MICE) will test ionization cooling of muons. In order to have effective ionization cooling, one must use an absorber that is made from a low-z material. The most effective low z materials for ionization cooling are hydrogen, helium, lithium hydride, lithium and beryllium, in that order. In order to measure the effect of material on cooling, several absorber materials must be used. This report describes a liquid-hydrogen absorber that is within a pair of superconducting focusing solenoids. The absorber must also be suitable for use with liquid helium. The following absorber components are discussed in this report; the absorber body, its heat exchanger, the hydrogen system, and the hydrogen safety. Absorber cooling and the thin windows are not discussed here.

  12. Lava cave microbial communities within mats and secondary mineral deposits: implications for life detection on other planets.

    PubMed

    Northup, D E; Melim, L A; Spilde, M N; Hathaway, J J M; Garcia, M G; Moya, M; Stone, F D; Boston, P J; Dapkevicius, M L N E; Riquelme, C

    2011-09-01

    Lava caves contain a wealth of yellow, white, pink, tan, and gold-colored microbial mats; but in addition to these clearly biological mats, there are many secondary mineral deposits that are nonbiological in appearance. Secondary mineral deposits examined include an amorphous copper-silicate deposit (Hawai'i) that is blue-green in color and contains reticulated and fuzzy filament morphologies. In the Azores, lava tubes contain iron-oxide formations, a soft ooze-like coating, and pink hexagons on basaltic glass, while gold-colored deposits are found in lava caves in New Mexico and Hawai'i. A combination of scanning electron microscopy (SEM) and molecular techniques was used to analyze these communities. Molecular analyses of the microbial mats and secondary mineral deposits revealed a community that contains 14 phyla of bacteria across three locations: the Azores, New Mexico, and Hawai'i. Similarities exist between bacterial phyla found in microbial mats and secondary minerals, but marked differences also occur, such as the lack of Actinobacteria in two-thirds of the secondary mineral deposits. The discovery that such deposits contain abundant life can help guide our detection of life on extraterrestrial bodies.

  13. Use of palm-mat geotextiles for rainsplash erosion control

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, R.; Fullen, M. A.; Davies, K.; Booth, C. A.

    2010-07-01

    Soil detachment by raindrop action (rainsplash erosion) is a very important subprocess of erosion by water. It is a particular problem in the UK as most soils are sandy or loamy sand in texture and lands have gentle to medium slope. However, few studies report potential rainsplash erosion control options under field conditions. Hence, the utilization of palm-mat geotextiles as a rainsplash erosion control technique was investigated at Hilton, east Shropshire, U.K. (52°33'5.7″ N, 2°19'18.3″ W). Geotextile-mats constructed from Borassus aethiopum (Borassus palm of West Africa) and Mauritia flexuosa (Buriti palm of South America) leaves are termed Borassus mats and Buriti mats, respectively. Two-year field experiments were conducted at Hilton to study the effects of emplacing Borassus and Buriti mats on rainsplash erosion of a loamy sand soil. Two sets (12 plots each) of experiments were established to study the effects of these mats on splash height and splash erosion. Splash height needs to be known to assess the transport mechanism of major soil fraction and its constituents on sloping land by rainsplash. In both sets, six randomly-selected plots were covered with mats, and the rest were bare. Results (during 22/01/2007‒23/01/2009; total precipitation = 1731.5 mm) show that Borassus mat-covered plots had ˜ 89% ( P < 0.001) less total splash erosion (2.97 kg m - 2 ) than bare plots (27.02 kg m - 2 ). Comparatively, mean splash height from Borassus mat-covered plots (0.12 m) was significantly ( P < 0.001) less than the bare plots, by ˜ 54%. However, Buriti mat-cover on bare plots had no significant ( P > 0.05) effect in rainsplash erosion control during that period, although plots with Buriti mats significantly ( P < 0.05) decreased splash height (by ˜ 18%) compared with bare plots (0.26 m). Buriti mats, probably due to their ˜ 43, 62 and 50% lower cover percentage (44%), mass per unit area (413 g - 2 ) and thickness (10 mm), respectively, compared with

  14. Superconducting Metallic Glass Transition-Edge-Sensors

    NASA Technical Reports Server (NTRS)

    Hays, Charles C. (Inventor)

    2013-01-01

    A superconducting metallic glass transition-edge sensor (MGTES) and a method for fabricating the MGTES are provided. A single-layer superconducting amorphous metal alloy is deposited on a substrate. The single-layer superconducting amorphous metal alloy is an absorber for the MGTES and is electrically connected to a circuit configured for readout and biasing to sense electromagnetic radiation.

  15. 30 CFR 77.513 - Insulating mats at power switches.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Insulating mats at power switches. 77.513... COAL MINES Electrical Equipment-General § 77.513 Insulating mats at power switches. Dry wooden... switchboards and power-control switches where shock hazards exist. However, metal plates on which a...

  16. 30 CFR 77.513 - Insulating mats at power switches.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Insulating mats at power switches. 77.513... COAL MINES Electrical Equipment-General § 77.513 Insulating mats at power switches. Dry wooden... switchboards and power-control switches where shock hazards exist. However, metal plates on which a...

  17. 30 CFR 77.513 - Insulating mats at power switches.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Insulating mats at power switches. 77.513... COAL MINES Electrical Equipment-General § 77.513 Insulating mats at power switches. Dry wooden... switchboards and power-control switches where shock hazards exist. However, metal plates on which a...

  18. Compositions and method of use of constructed microbial mats

    DOEpatents

    Bender, Judith A.; Phillips, Peter C.

    1997-01-01

    Compositions and methods of use of constructed microbial mats, comprising cyanobacteria and purple autotrophic bacteria and an organic nutrient source, in a laminated structure, are described. The constructed microbial mat is used for bioremediation of different individual contaminants and for mixed or multiple contaminants, and for production of beneficial compositions and molecules.

  19. Effects of preprocessing method on TVOC emission of car mat

    NASA Astrophysics Data System (ADS)

    Wang, Min; Jia, Li

    2013-02-01

    The effects of the mat preprocessing method on total volatile organic compounds (TVOC) emission of car mat are studied in this paper. An appropriate TVOC emission period for car mat is suggested. The emission factors for total volatile organic compounds from three kinds of new car mats are discussed. The car mats are preprocessed by washing, baking and ventilation. When car mats are preprocessed by washing, the TVOC emission for all samples tested are lower than that preprocessed in other methods. The TVOC emission is in stable situation for a minimum of 4 days. The TVOC emitted from some samples may exceed 2500μg/kg. But the TVOC emitted from washed Polyamide (PA) and wool mat is less than 2500μg/kg. The emission factors of total volatile organic compounds (TVOC) are experimentally investigated in the case of different preprocessing methods. The air temperature in environment chamber and the water temperature for washing are important factors influencing on emission of car mats.

  20. MAT@USC Candidates and Latino English Language Learners

    ERIC Educational Resources Information Center

    Lomeli, Cynthia Leticia

    2012-01-01

    The purpose of this study was to further understand the perceptions of MAT@USC teacher candidates and how their perceptions and previous experiences affect the educational experiences of Latino English language learners. Three questions were developed to guide this study: (1) What are the perceptions of MAT@USC candidates in selected courses…

  1. 30 CFR 77.513 - Insulating mats at power switches.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Insulating mats at power switches. 77.513... COAL MINES Electrical Equipment-General § 77.513 Insulating mats at power switches. Dry wooden... switchboards and power-control switches where shock hazards exist. However, metal plates on which a...

  2. 30 CFR 77.513 - Insulating mats at power switches.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Insulating mats at power switches. 77.513... COAL MINES Electrical Equipment-General § 77.513 Insulating mats at power switches. Dry wooden... switchboards and power-control switches where shock hazards exist. However, metal plates on which a...

  3. Ferroelectrics based absorbing layers

    NASA Astrophysics Data System (ADS)

    Hao, Jianping; Sadaune, Véronique; Burgnies, Ludovic; Lippens, Didier

    2014-07-01

    We show that ferroelectrics-based periodic structure made of BaSrTiO3 (BST) cubes, arrayed onto a metal plate with a thin dielectric spacer film exhibit a dramatic enhancement of absorbance with value close to unity. The enhancement is found around the Mie magnetic resonance of the Ferroelectrics cubes with the backside metal layer stopping any transmitted waves. It also involves quasi-perfect impedance matching resulting in reflection suppression via simultaneous magnetic and electrical activities. In addition, it was shown numerically the existence of a periodicity optimum, which is explained from surface waves analysis along with trade-off between the resonance damping and the intrinsic loss of ferroelectrics cubes. An experimental verification in a hollow waveguide configuration with a good comparison with full-wave numerical modelling is at last reported by measuring the scattering parameters of single and dual BST cubes schemes pointing out coupling effects for densely packed structures.

  4. Dual broadband metamaterial absorber.

    PubMed

    Kim, Young Ju; Yoo, Young Joon; Kim, Ki Won; Rhee, Joo Yull; Kim, Yong Hwan; Lee, YoungPak

    2015-02-23

    We propose polarization-independent and dual-broadband metamaterial absorbers at microwave frequencies. This is a periodic meta-atom array consisting of metal-dielectric-multilayer truncated cones. We demonstrate not only one broadband absorption from the fundamental magnetic resonances but additional broadband absorption in high-frequency range using the third-harmonic resonance, by both simulation and experiment. In simulation, the absorption was over 90% in 3.93-6.05 GHz, and 11.64-14.55 GHz. The corresponding experimental absorption bands over 90% were 3.88-6.08 GHz, 9.95-10.46 GHz and 11.86-13.84 GHz, respectively. The origin of absorption bands was elucidated. Furthermore, it is independent of polarization angle owing to the multilayered circular structures. The design is scalable to smaller size for the infrared and the visible ranges.

  5. THz-metamaterial absorbers

    NASA Astrophysics Data System (ADS)

    Tuong Pham, Van; Park, J. W.; Vu, Dinh Lam; Zheng, H. Y.; Rhee, J. Y.; Kim, K. W.; Lee, Y. P.

    2013-03-01

    An ultrabroad-band metamaterial absorber was investigated in mid-IR regime based on a similar model in previous work. The high absorption of metamaterial was obtained in a band of 8-11.7 THz with energy loss distributed in SiO2, which is appropriate potentially for solar-cell applications. A perfect absorption peak was provided by using a sandwich structure with periodical anti-dot pattern in the IR region, getting closed to visible-band metamaterials. The dimensional parameters were examined for the corresponding fabrication. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November, 2012, Ha Long, Vietnam.

  6. Role of microbial mats in the fossilization of soft tissues

    NASA Astrophysics Data System (ADS)

    Wilby, Philip R.; Briggs, Derek E. G.; Bernier, Paul; Gaillard, Christian

    1996-09-01

    It has been speculated that microbial mats are an important agent in the fossilization of soft tissues, particularly when apatite (Ca5[CO3, PO4]3[OH, F]) is involved. This has been tested by chemical analyses of the Jurassic limestones of Cerin, France, where phosphatized soft tissues are abundant and are associated with unequivocal microbial mats. The sedimentary distribution of P, K, and Fe following deposition was controlled by the presence of the mats. P concentrations in the mats may approach 2.5 times those elsewhere in the sediment. The highest P concentrations correlate with the occurrence of phosphatized soft tissues. This is the first analytical evidence to demonstrate a fundamental role for microbial mats in the preservation of soft-bodied fossils.

  7. Research on Bayes matting algorithm based on Gaussian mixture model

    NASA Astrophysics Data System (ADS)

    Quan, Wei; Jiang, Shan; Han, Cheng; Zhang, Chao; Jiang, Zhengang

    2015-12-01

    The digital matting problem is a classical problem of imaging. It aims at separating non-rectangular foreground objects from a background image, and compositing with a new background image. Accurate matting determines the quality of the compositing image. A Bayesian matting Algorithm Based on Gaussian Mixture Model is proposed to solve this matting problem. Firstly, the traditional Bayesian framework is improved by introducing Gaussian mixture model. Then, a weighting factor is added in order to suppress the noises of the compositing images. Finally, the effect is further improved by regulating the user's input. This algorithm is applied to matting jobs of classical images. The results are compared to the traditional Bayesian method. It is shown that our algorithm has better performance in detail such as hair. Our algorithm eliminates the noise well. And it is very effectively in dealing with the kind of work, such as interested objects with intricate boundaries.

  8. Dynamic heat and moisture transfer in bulky PAN nanofiber mats

    NASA Astrophysics Data System (ADS)

    Borhani, Sedigheh; Etemad, Seyed Gholamreza; Ravandi, Seyed Abdolkarim Hosseini

    2011-07-01

    In this study a non-conventional electrospinning technique was designed for the production of high bulky polyacrylonitrile (PAN) nanofiber mats. Optimum nanofiber mats are achieved with 15 wt.% solution of PAN in dimethylformamide. Such mats result in a bulk porosity which is as high as 99.9 and a density as low as 0.84 × 10-3 g/cm3. The effect of the porosity of nanofiber mats on the air permeability and coupled heat and moisture transfer of fibers was investigated. Based on the results, high bulky nanofiber mats possess high heat and moisture transfer. Experimental data reveal that upon a slight decrease in the bulk porosity, air permeability and heat transfer decrease noticeably, while moisture transfer variation is low.

  9. Elastic-plastic behavior of non-woven fibrous mats

    NASA Astrophysics Data System (ADS)

    Silberstein, Meredith N.; Pai, Chia-Ling; Rutledge, Gregory C.; Boyce, Mary C.

    2012-02-01

    Electrospinning is a novel method for creating non-woven polymer mats that have high surface area and high porosity. These attributes make them ideal candidates for multifunctional composites. Understanding the mechanical properties as a function of fiber properties and mat microstructure can aid in designing these composites. Further, a constitutive model which captures the membrane stress-strain behavior as a function of fiber properties and the geometry of the fibrous network would be a powerful design tool. Here, mats electrospun from amorphous polyamide are used as a model system. The elastic-plastic behavior of single fibers are obtained in tensile tests. Uniaxial monotonic and cyclic tensile tests are conducted on non-woven mats. The mat exhibits elastic-plastic stress-strain behavior. The transverse strain behavior provides important complementary data, showing a negligible initial Poisson's ratio followed by a transverse:axial strain ratio greater than -1:1 after an axial strain of 0.02. A triangulated framework has been developed to emulate the fibrous network structure of the mat. The micromechanically based model incorporates the elastic-plastic behavior of single fibers into a macroscopic membrane model of the mat. This representative volume element based model is shown to capture the uniaxial elastic-plastic response of the mat under monotonic and cyclic loading. The initial modulus and yield stress of the mat are governed by the fiber properties, the network geometry, and the network density. The transverse strain behavior is linked to discrete deformation mechanisms of the fibrous mat structure including fiber alignment, fiber bending, and network consolidation. The model is further validated in comparison to experiments under different constrained axial loading conditions and found to capture the constraint effect on stiffness, yield, post-yield hardening, and post-yield transverse strain behavior. Due to the direct connection between

  10. Benthic Marine Cyanobacterial Mat Ecosystems: Biogeochemistry and Biomarkers

    NASA Technical Reports Server (NTRS)

    DesMarais, David J.; DeVincenzi, Donald (Technical Monitor)

    2001-01-01

    Cyanobacterial mats are complete ecosystems that can include processes of primary production, diagenesis and lithification. Light sustains oxygenic photosynthesis, which in turn provides energy, organic matter and oxygen to the community. Due to both absorption and scattering phenomena, incident light is transformed with depth in the mat, both in intensity and spectral composition. Mobile photo synthesizers optimize their position with respect to this light gradient. When photosynthesis ceases at night, the upper layers of the mat become reduced and sulfidic. Counteracting gradients of oxygen and sulfide combine to provide daily-contrasting environments separated on a scale of a few mm. The functional complexity of mats, coupled with the highly proximal and ordered spatial arrangement of biota, offers the potential for a staggering number of interactions. At a minimum, the products of each functional group of microorganisms affect the other groups both positively and negatively. For example, cyanobacteria generate organic matter (potential substrates) but also oxygen (a toxin for many anaerobes). Anaerobic activity recycles nutrients to the photosynthesizers but also generates potentially toxic sulfide. The combination of benefits and hazards of light, oxygen and sulfide promotes the allocation of the various essential mat processes between light and dark periods, and to various depths in the mat. Observations of mats have produced numerous surprises. For example, obligately anaerobic processes can occur in the presence of abundant oxygen, highly reduced gases are produced in the presence of abundant sulfate, meiofauna thrive at high sulfide concentrations, and the mats' constituent populations respond to environmental changes in complex ways. While photosynthetic bacteria dominate the biomass and productivity of the mat, nonphotosynthetic, anaerobic processes constitute the ultimate biological filter on the ecosystem's emergent biosignatures, including those

  11. MAT2A mutations predispose individuals to thoracic aortic aneurysms.

    PubMed

    Guo, Dong-chuan; Gong, Limin; Regalado, Ellen S; Santos-Cortez, Regie L; Zhao, Ren; Cai, Bo; Veeraraghavan, Sudha; Prakash, Siddharth K; Johnson, Ralph J; Muilenburg, Ann; Willing, Marcia; Jondeau, Guillaume; Boileau, Catherine; Pannu, Hariyadarshi; Moran, Rocio; Debacker, Julie; Bamshad, Michael J; Shendure, Jay; Nickerson, Deborah A; Leal, Suzanne M; Raman, C S; Swindell, Eric C; Milewicz, Dianna M

    2015-01-08

    Up to 20% of individuals who have thoracic aortic aneurysms or acute aortic dissections but who do not have syndromic features have a family history of thoracic aortic disease. Significant genetic heterogeneity is established for this familial condition. Whole-genome linkage analysis and exome sequencing of distant relatives from a large family with autosomal-dominant inheritance of thoracic aortic aneurysms variably associated with the bicuspid aortic valve was used for identification of additional genes predisposing individuals to this condition. A rare variant, c.1031A>C (p.Glu344Ala), was identified in MAT2A, which encodes methionine adenosyltransferase II alpha (MAT IIα). This variant segregated with disease in the family, and Sanger sequencing of DNA from affected probands from unrelated families with thoracic aortic disease identified another MAT2A rare variant, c.1067G>A (p.Arg356His). Evidence that these variants predispose individuals to thoracic aortic aneurysms and dissections includes the following: there is a paucity of rare variants in MAT2A in the population; amino acids Glu344 and Arg356 are conserved from humans to zebrafish; and substitutions of these amino acids in MAT Iα are found in individuals with hypermethioninemia. Structural analysis suggested that p.Glu344Ala and p.Arg356His disrupt MAT IIα enzyme function. Knockdown of mat2aa in zebrafish via morpholino oligomers disrupted cardiovascular development. Co-transfected wild-type human MAT2A mRNA rescued defects of zebrafish cardiovascular development at significantly higher levels than mRNA edited to express either the Glu344 or Arg356 mutants, providing further evidence that the p.Glu344Ala and p.Arg356His substitutions impair MAT IIα function. The data presented here support the conclusion that rare genetic variants in MAT2A predispose individuals to thoracic aortic disease.

  12. MAT2A Mutations Predispose Individuals to Thoracic Aortic Aneurysms

    PubMed Central

    Guo, Dong-chuan; Gong, Limin; Regalado, Ellen S.; Santos-Cortez, Regie L.; Zhao, Ren; Cai, Bo; Veeraraghavan, Sudha; Prakash, Siddharth K.; Johnson, Ralph J.; Muilenburg, Ann; Willing, Marcia; Jondeau, Guillaume; Boileau, Catherine; Pannu, Hariyadarshi; Moran, Rocio; Debacker, Julie; Bamshad, Michael J.; Shendure, Jay; Nickerson, Deborah A.; Leal, Suzanne M.; Raman, C.S.; Swindell, Eric C.; Milewicz, Dianna M.

    2015-01-01

    Up to 20% of individuals who have thoracic aortic aneurysms or acute aortic dissections but who do not have syndromic features have a family history of thoracic aortic disease. Significant genetic heterogeneity is established for this familial condition. Whole-genome linkage analysis and exome sequencing of distant relatives from a large family with autosomal-dominant inheritance of thoracic aortic aneurysms variably associated with the bicuspid aortic valve was used for identification of additional genes predisposing individuals to this condition. A rare variant, c.1031A>C (p.Glu344Ala), was identified in MAT2A, which encodes methionine adenosyltransferase II alpha (MAT IIα). This variant segregated with disease in the family, and Sanger sequencing of DNA from affected probands from unrelated families with thoracic aortic disease identified another MAT2A rare variant, c.1067G>A (p.Arg356His). Evidence that these variants predispose individuals to thoracic aortic aneurysms and dissections includes the following: there is a paucity of rare variants in MAT2A in the population; amino acids Glu344 and Arg356 are conserved from humans to zebrafish; and substitutions of these amino acids in MAT Iα are found in individuals with hypermethioninemia. Structural analysis suggested that p.Glu344Ala and p.Arg356His disrupt MAT IIα enzyme function. Knockdown of mat2aa in zebrafish via morpholino oligomers disrupted cardiovascular development. Co-transfected wild-type human MAT2A mRNA rescued defects of zebrafish cardiovascular development at significantly higher levels than mRNA edited to express either the Glu344 or Arg356 mutants, providing further evidence that the p.Glu344Ala and p.Arg356His substitutions impair MAT IIα function. The data presented here support the conclusion that rare genetic variants in MAT2A predispose individuals to thoracic aortic disease. PMID:25557781

  13. Pinhole Glasses

    ERIC Educational Resources Information Center

    Colicchia, Giuseppe; Hopf, Martin; Wiesner, Hartmut; Zollman, Dean

    2008-01-01

    Eye aberrations are commonly corrected by lenses that restore vision by altering rays before they pass through the cornea. Some modern promoters claim that pinhole glasses are better than conventional lenses in correcting all kinds of refractive defects such as myopia (nearsighted), hyperopia (farsighted), astigmatisms, and presbyopia. Do pinhole…

  14. Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam (Inventor)

    1992-01-01

    A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  15. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P. (Inventor)

    1995-01-01

    A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  16. Electrochemically regenerable carbon dioxide absorber

    NASA Technical Reports Server (NTRS)

    Woods, R. R.; Marshall, R. D.; Schubert, F. H.; Heppner, D. B.

    1979-01-01

    Preliminary designs were generated for two electrochemically regenerable carbon dioxide absorber concepts. Initially, an electrochemically regenerable absorption bed concept was designed. This concept incorporated the required electrochemical regeneration components in the absorber design, permitting the absorbent to be regenerated within the absorption bed. This hardware was identified as the electrochemical absorber hardware. The second hardware concept separated the functional components of the regeneration and absorption process. This design approach minimized the extravehicular activity component volume by eliminating regeneration hardware components within the absorber. The electrochemical absorber hardware was extensively characterized for major operating parameters such as inlet carbon dioxide partial pressure, process air flow rate, operational pressure, inlet relative humidity, regeneration current density and absorption/regeneration cycle endurance testing.

  17. Broadband patterned magnetic microwave absorber

    SciTech Connect

    Li, Wei; Wu, Tianlong; Wang, Wei; Guan, Jianguo; Zhai, Pengcheng

    2014-07-28

    It is a tough task to greatly improve the working bandwidth for the traditional flat microwave absorbers because of the restriction of available material parameters. In this work, a simple patterning method is proposed to drastically broaden the absorption bandwidth of a conventional magnetic absorber. As a demonstration, an ultra-broadband microwave absorber with more than 90% absorption in the frequency range of 4–40 GHz is designed and experimentally realized, which has a thin thickness of 3.7 mm and a light weight equivalent to a 2-mm-thick flat absorber. In such a patterned absorber, the broadband strong absorption is mainly originated from the simultaneous incorporation of multiple λ/4 resonances and edge diffraction effects. This work provides a facile route to greatly extend the microwave absorption bandwidth for the currently available absorbing materials.

  18. Liquid Hydrogen Absorber for MICE

    SciTech Connect

    Ishimoto, S.; Suzuki, S.; Yoshida, M.; Green, Michael A.; Kuno, Y.; Lau, Wing

    2010-05-30

    Liquid hydrogen absorbers for the Muon Ionization Cooling Experiment (MICE) have been developed, and the first absorber has been tested at KEK. In the preliminary test at KEK we have successfully filled the absorber with {approx}2 liters of liquid hydrogen. The measured hydrogen condensation speed was 2.5 liters/day at 1.0 bar. No hydrogen leakage to vacuum was found between 300 K and 20 K. The MICE experiment includes three AFC (absorber focusing coil) modules, each containing a 21 liter liquid hydrogen absorber made of aluminum. The AFC module has safety windows to separate its vacuum from that of neighboring modules. Liquid hydrogen is supplied from a cryocooler with cooling power 1.5 W at 4.2 K. The first absorber will be assembled in the AFC module and installed in MICE at RAL.

  19. First insights into fern matK phylogeny.

    PubMed

    Kuo, Li-Yaung; Li, Fay-Wei; Chiou, Wen-Liang; Wang, Chun-Neng

    2011-06-01

    MatK, the only maturase gene in the land plant plastid genome, is a very popular phylogenetic marker that has been extensively applied in reconstructing angiosperm phylogeny. However, the use of matK in fern phylogeny is largely unknown, due to difficulties with amplification: ferns have lost the flanking trnK exons, typically the region used for designing stable priming sites. We developed primers that are either universal or lineage-specific that successfully amplify matK across all fern families. To evaluate whether matK is as powerful a phylogenetic marker in ferns as in angiosperms, we compared its sequence characteristics and phylogenetic performance to those of rbcL and atpA. Among these three genes, matK has the highest variability and substitution evenness, yet shows the least homoplasy. Most importantly, applying matK in fern phylogenetics better resolved relationships among families, especially within eupolypods I and II. Here we demonstrate the power of matK for fern phylogenetic reconstruction, as well as provide primers and extensive sequence data that will greatly facilitate future evolutionary studies of ferns.

  20. Development of a carbonaceous selective absorber for solar thermal energy collection and process for its formation

    NASA Astrophysics Data System (ADS)

    Garrison, John D.

    1989-02-01

    The main goal of the US Department of Energy supported part of this project is to develop information about controlling the complicated chemical processes involved in the formation of a carbonaceous selective absorber and learn what equipment will allow production of this absorber commercially. The work necessary to accomplish this goal is not yet complete. Formation of the carbonaceous selective absorber in the conveyor oven tried so far has been unsatisfactory, because the proper conditions for applying the carbonaceous coating in each conveyor oven fabricated, either have been difficult to obtain, or have been difficult to maintain over an extended period of time. A new conveyor oven is nearing completion which is expected to allow formation of the carbonaceous selective absorber on absorber tubes in a continuous operation over many days without the necessity of cleaning the conveyor oven or changing the thickness of the electroplated nickel catalyst to compensate for changes in the coating environment in the oven. Work under this project concerned with forming and sealing glass panels to test ideas on evacuated glass solar collector designs and production have been generally quite satisfactory. Delays in completion of the selective absorber work, has caused postponement of the fabrication of a small prototype evacuated glass solar collector panel. Preliminary cost estimates of the selective absorber and solar collector panel indicate that this collector system should be lower in cost than evacuated solar collectors now on the market.

  1. Manganese Influences Carbonate Precipitation in a Laminated Microbial Mat

    NASA Astrophysics Data System (ADS)

    Krusor, M.; Grim, S. L.; Wilmeth, D.; Johnson, H.; Berelson, W.; Stevenson, B. S.; Stamps, B. W.; Corsetti, F. A.; Spear, J. R.

    2015-12-01

    Investigating mineralization within modern microbial mats informs our interpretation of ancient microbialites and the mineralization process. Microbial mats in Little Hot Creek (LHC), California contain 4 distinct layers with different microbiota. Each layer of the mat is supersaturated with regard to calcium carbonate (CaCO3), which increases with depth. Total organic carbon decreases with depth through the mat. We used 13C-labeled bicarbonate incubations of each mat layer to calculate growth rates of organic carbon and CaCO3 within the mat. Incubations were also amended with Mn or Mg to test their effect on rates of CaCO3 and organic carbon formation. The Mn-amended top layer increased CaCO3 precipitation and organic carbon growth. Mn increased organic carbon production in the lowest layer to a lesser extent, but not growth of CaCO3. Mn addition had no effect on growth rates in the two intervening layers. Mg amendment stimulated only organic carbon formation in the top layer, with little to no effect on the lower layers or overall CaCO3 formation. We attribute the elevated CaCO3 precipitation noted after Mn addition to increased oxygenic photosynthetic activity. Oxygenic photosynthesis requires Mn as an enzyme cofactor and promotes carbonate precipitation. We propose that the phototrophic community was responsible for most of the CaCO3 precipitation in the upper layer. Phototrophs gradually moved upwards for optimal access to sunlight, and as the mat grew, "tenant" microorganisms inhabited the lower carbonate layers while the "builders" remained on top. The relatively constant percentages of inorganic carbon below the top layer combined with observed minimal CaCO3 precipitation under laboratory conditions suggest that additional research into potential metabolisms that impact carbonate formation would be informative. These results improve our understanding of the linkages between microbial metabolisms, carbonate precipitation in microbial mats, and the potential

  2. Using Intact Iron Microbial Mats to Gain Insights Into Mat Ecology and Geochemical Niche at the Microbial Scale

    NASA Astrophysics Data System (ADS)

    Glazer, B. T.; Chan, C. S. Y.; Mcallister, S.; Leavitt, A.; Emerson, D.

    2015-12-01

    Microbial mats are formed by microorganisms working in coordinated symbiosis, often benefitting the community by controlling the local geochemical or physical environment. Thus, the ecology of the mat depends on the individual roles of microbes organized into niches within a larger architecture. Chemolithotrophic Fe-oxidizing bacteria (FeOB) form distinctive Fe oxyhydroxide biominerals which constitute the building blocks of the mat. However, the majority of our progress has been in understanding the overall community structure. Understanding the physical mat structure on the microbial scale is important to unraveling FeOB evolution, the biogeochemistry and ecology of Fe-rich habitats, and ultimately interpreting FeOB biosignatures in the rock record. Mats in freshwater and marine environments contain strikingly similar biomineral morphologies, yet they are formed by phylogenetically distinct microorganisms. This suggests that the overall architecture and underlying genetics of freshwater and marine mats has evolved to serve particular roles specific to Fe oxidation. Thus, we conducted a comparative study of Fe seep freshwater mats and marine hydrothermal mats. We have developed a new approach to sampling Fe mats in order to preserve the delicate structure for analysis by confocal and scanning electron microscopy. Our analyses of these intact mats show that freshwater and marine mats are similarly initiated by a single type of structure-former. These ecosystem engineers form either a hollow sheath or a twisted stalk biomineral during mat formation, with a highly directional structure. These microbes appear to be the vanguard organisms that anchor the community within oxygen/Fe(II) gradients, further allowing for community succession in the mat interior as evidenced by other mineralized morphologies. Patterns in biomineral thickness and directionality were indicative of redox gradients and temporal changes in the geochemical environment. These observations show that

  3. The MAT locus genes play different roles in sexual reproduction and pathogenesis in Fusarium graminearum.

    PubMed

    Zheng, Qian; Hou, Rui; Juanyu; Zhang; Ma, Jiwen; Wu, Zhongshou; Wang, Guanghui; Wang, Chenfang; Xu, Jin-Rong

    2013-01-01

    Sexual reproduction plays a critical role in the infection cycle of Fusarium graminearum because ascospores are the primary inoculum. As a homothallic ascomycete, F. graminearum contains both the MAT1-1 and MAT1-2-1 loci in the genome. To better understand their functions and regulations in sexual reproduction and pathogenesis, in this study we assayed the expression, interactions, and mutant phenotypes of individual MAT locus genes. Whereas the expression of MAT1-1-1 and MAT12-1 rapidly increased after perithecial induction and began to decline after 1 day post-perithecial induction (dpi), the expression of MAT1-1-2 and MAT1-1-3 peaked at 4 dpi. MAT1-1-2 and MAT1-1-3 had a similar expression profile and likely are controlled by a bidirectional promoter. Although none of the MAT locus genes were essential for perithecium formation, all of them were required for ascosporogenesis in self-crosses. In outcrosses, the mat11-1-2 and mat11-1-3 mutants were fertile but the mat1-1-1 and mat1-2-1 mutants displayed male- and female-specific defects, respectively. The mat1-2-1 mutant was reduced in FgSO expression and hyphal fusion. Mat1-1-2 interacted with all other MAT locus transcription factors, suggesting that they may form a protein complex during sexual reproduction. Mat1-1-1 also interacted with FgMcm1, which may play a role in controlling cell identity and sexual development. Interestingly, the mat1-1-1 and mat1-2-1 mutants were reduced in virulence in corn stalk rot assays although none of the MAT locus genes was important for wheat infection. The MAT1-1-1 and MAT1-2-1 genes may play a host-specific role in colonization of corn stalks.

  4. Electrochromic Glasses.

    DTIC Science & Technology

    1980-07-31

    Li20-B203 and Na20-B203 or Te02 . These glasses exhibit for the first time, electrochromic and photochromic behaviour and have potential for use in...the complete spectral distribution of the absorption at levels of 10- cm- I for the first time. In the past, it was only possible to measure low...distribution of the absorption at levels at 10 -cm it was possible, for the first time, to identify extrinsic impurities in highly transparent solids. This

  5. Electrospun graphene-ZnO nanofiber mats for photocatalysis applications

    NASA Astrophysics Data System (ADS)

    An, Seongpil; Joshi, Bhavana N.; Lee, Min Wook; Kim, Na Young; Yoon, Sam S.

    2014-03-01

    Graphene-decorated zinc oxide (G-ZnO) nanofibers were fabricated, for the first time, by electrospinning. The effect of graphene concentration on the properties of G-ZnO mats were investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and thermo gravimetric analysis. The G-ZnO mats decorated with 0.5 wt.% of graphene showed excellent photocatalytic activity through degradation of methylene blue under UV irradiation. The highest photocatalytic activity (80% degradation) was observed for 0.5 wt.% G-ZnO mats annealed at 400 °C after 4 h of UV irradiation.

  6. Protocyanobacteria: Oxygenic and Anoxygenic photosynthesis in mat-forming bacteria

    NASA Technical Reports Server (NTRS)

    Cohen, Y.

    1985-01-01

    The oldest record of life is preserved in prePhanerozoic stromatolites dated 3500 million years old and is most likely of filamentous mat-forming cyanobacteria. The sedimentary records of cyanobacterial mats in stromatolites are the most abundant record of life throughout the prePhanerozoic. Stromatolites persisted into the Phanerozoic Eon, yet they become much less pronounced relative to earlier ones. The abundance and persistence of cyanobacterial mats throughout most of geological time point to the evolutionary success of these kinds of microbial communities and their possible role in the evolution of the earth and atmosphere.

  7. Water flow and solute transport in floating fen root mats

    NASA Astrophysics Data System (ADS)

    Stofberg, Sija F.; EATM van der Zee, Sjoerd

    2015-04-01

    Floating fens are valuable wetlands, found in North-Western Europe, that are formed by floating root mats when old turf ponds are colonized by plants. These terrestrialization ecosystems are known for their biodiversity and the presence of rare plant species, and the root mats reveal different vegetation zones at a small scale. The vegetation zones are a result of strong gradients in abiotic conditions, including groundwater dynamics, nutrients and pH. To prevent irreversible drought effects such as land subsidence and mineralization of peat, water management involves import of water from elsewhere to maintain constant surface water levels. Imported water may have elevated levels of salinity during dry summers, and salt exposure may threaten the vegetation. To assess the risk of exposure of the rare plant species to salinity, the hydrology of such root mats must be understood. Physical properties of root mats have scarcely been investigated. We have measured soil characteristics, hydraulic conductivity, vertical root mat movement and groundwater dynamics in a floating root mat in the nature reserve Nieuwkoopse Plassen, in the Netherlands. The root mat mostly consists of roots and organic material, in which the soil has a high saturated water content, and strongly varies in its stage of decomposition. We have found a distinct negative correlation between degree of decomposition and hydraulic conductivity, similar to observations for bogs in the literature. Our results show that the relatively young, thin edge of the root mat that colonizes the surface water has a high hydraulic conductivity and floats in the surface water, resulting in very small groundwater fluctuations within the root mat. The older part of the root mat, that is connected to the deeper peat layers is hydrologically more isolated and the material has a lower conductivity. Here, the groundwater fluctuates strongly with atmospheric forcing. The zones of hydraulic properties and vegetation, appear to

  8. Glass-heat-pipe evacuated-tube solar collector

    SciTech Connect

    McConnell, R.D.; VanSant, J.H.

    1981-08-06

    A glass heat pipe is adapted for use as a solar energy absorber in an evacuated tube solar collector and for transferring the absorbed solar energy to a working fluid medium or heat sink for storage or practical use. A capillary wick is formed of granular glass particles fused together by heat on the inside surface of the heat pipe with a water glass binder solution to enhance capillary drive distribution of the thermal transfer fluid in the heat pipe throughout the entire inside surface of the evaporator portion of the heat pipe. Selective coatings are used on the heat pipe surface to maximize solar absorption and minimize energy radiation, and the glass wick can alternatively be fabricated with granular particles of black glass or obsidian.

  9. Absorber Coatings for Mid-Infrared Astrophysics

    NASA Astrophysics Data System (ADS)

    Baker, Dahlia Anne; Wollack, Edward; Rostem, Karwan

    2017-01-01

    Control over optical response is an important aspect of instrument design for astrophysical imaging. Here we consider a mid-infrared absorber coating proposed for use on HIRMES (High Resolution Mid-Infrared Spectrometer), a cryogenic spectrometer which will fly on the SOFIA (Stratospheric Observatory for Infrared Astronomy) aircraft. The aim of this effort is to develop an absorptive coating for the 20-200 microns spectral range based on a graphene loaded epoxy binder (Epotek 377H) and glass microsphere scatterers (3M K1). The coatings electromagnetic response was modeled using a Matlab script and the glass microspheres were characterized by the measured size distribution, the dielectric constant, and the filling fraction. Images of the microspheres taken by a microscope were used to determine the size distribution with an ImageJ particle analysis program. Representative test samples for optical evaluation were fabricated for characterization via infrared Fourier transform spectroscopy. The optical tests will determine the material’s absorptance and reflectance. These test results will be compared to the modeled response.

  10. Energy absorber for the CETA

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1994-01-01

    The energy absorber that was developed for the CETA (Crew Equipment and Translation Aid) on Space Station Freedom is a metal on metal frictional type and has a load regulating feature that prevents excessive stroking loads from occurring while in operation. This paper highlights some of the design and operating aspects and the testing of this energy absorber.

  11. Improvement Of The Helmholtz Absorber

    NASA Technical Reports Server (NTRS)

    Morrow, Duane L.

    1992-01-01

    Helmholtz-resonator system improved to enable it to absorb sound at more than one frequency without appreciable loss of effectiveness at primary frequency. Addition of annular cavities enables absorption of sound at harmonic frequencies in addition to primary frequency. Improved absorber designed for use on structures of high transmission loss. Applied to such machines as fixed-speed engines and fans.

  12. Metal-shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P.

    1971-01-01

    Device, consisting of tongue of thin aluminum alloy strip, pull tab, slotted steel plate which serves as cutter, and steel buckle, absorbs mechanical energy when its ends are subjected to tensile loading. Device is applicable as auxiliary shock absorbing anchor for automobile and airplane safety belts.

  13. Leaf absorbance and photosynthesis

    NASA Technical Reports Server (NTRS)

    Schurer, Kees

    1994-01-01

    The absorption spectrum of a leaf is often thought to contain some clues to the photosynthetic action spectrum of chlorophyll. Of course, absorption of photons is needed for photosynthesis, but the reverse, photosynthesis when there is absorption, is not necessarily true. As a check on the existence of absorption limits we measured spectra for a few different leaves. Two techniques for measuring absorption have been used, viz. the separate determination of the diffuse reflectance and the diffuse transmittance with the leaf at a port of an integrating sphere and the direct determination of the non-absorbed fraction with the leaf in the sphere. In a cross-check both methods yielded the same results for the absorption spectrum. The spectrum of a Fuchsia leaf, covering the short-wave region from 350 to 2500 nm, shows a high absorption in UV, blue and red, the well known dip in the green and a steep fall-off at 700 nm. Absorption drops to virtually zero in the near infrared, with subsequent absorptions, corresponding to the water absorption bands. In more detailed spectra, taken at 5 nm intervals with a 5 nm bandwidth, differences in chlorophyll content show in the different depths of the dip around 550 nm and in a small shift of the absorption edge at 700 nm. Spectra for Geranium (Pelargonium zonale) and Hibiscus (with a higher chlorophyll content) show that the upper limit for photosynthesis can not be much above 700 nm. No evidence, however, is to be seen of a lower limit for photosynthesis and, in fact, some experiments down to 300 nm still did not show a decrease of the absorption although it is well recognized that no photosynthesis results with 300 nm wavelengths.

  14. Creep and creep-rupture behavior of a continuous strand, swirl mat reinforced polymer composite in automotive environments

    SciTech Connect

    Ren, W.; Brinkman, C.R.

    1998-12-31

    Creep and creep-rupture behavior of an isocyanurate based polyurethane matrix with a continuous strand, swirl mat E-glass reinforcement was investigated for automotive applications. The material under stress was exposed to various automobile service environments. Results show that environment has substantial effects on its creep and creep-rupture properties. Proposed design guide lines and stress reduction factors were developed for various automotive environments. These composites are considered candidate structural materials for light weight and fuel efficient automobiles of the future.

  15. Microbial mats and the early evolution of life

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1990-01-01

    Microbial mats have descended from perhaps the oldest and most widespread biological communities known. Mats harbor microbes that are crucial for studies of bacterial phylogeny and physiology. They illustrate how several oxygen-sensitive biochemical processes have adapted to oxygen, and they show how life adapted to dry land long before the rise of plants. The search for the earliest grazing protists and metazoa in stromatolites is aided by observations of mats: in them, organic compounds characteristic of ancient photosynthetic protists can be identified. Recent mat studies suggest that the 13C/12C increase observed over geological time in stromatolitic organic matter was driven at least in part by a long-term decline in atmospheric carbon dioxide levels.

  16. A Modular Sensorized Mat for Monitoring Infant Posture

    PubMed Central

    Donati, Marco; Cecchi, Francesca; Bonaccorso, Filippo; Branciforte, Marco; Dario, Paolo; Vitiello, Nicola

    2014-01-01

    We present a novel sensorized mat for monitoring infant's posture through the measure of pressure maps. The pressure-sensitive mat is based on an optoelectronic technology developed in the last few years at Scuola Superiore Sant'Anna: a soft silicone skin cover, which constitutes the mat, participates in the transduction principle and provides the mat with compliance. The device has a modular structure (with a minimum of one and a maximum of six sub-modules, and a total surface area of about 1 m2) that enables dimensional adaptation of the pressure-sensitive area to different specific applications. The system consists of on-board electronics for data collection, pre-elaboration, and transmission to a remote computing unit for analysis and posture classification. In this work we present a complete description of the sensing apparatus along with its experimental characterization and validation with five healthy infants. PMID:24385029

  17. Microbial mats and modern stromatolites in Shark Bay, Western Australia

    NASA Technical Reports Server (NTRS)

    Golubic, S.

    1985-01-01

    Distribution, external morphology, texture, and microbial composition of microbial mats in Hamelin Pool, Shark Bay, Western Australia, have been studied and reviewed along a composite representative profile starting from the permanently submerged zone, across the zones of periodic flooding, toward permanently emerged land and coastal dunes. The following nine types of algal mats have been recognized: colloform, gelatinous, smooth, pincushion, tufted, mamillate, film, reticulate, and blister. Solar ponds represent a particular environment. The mat types represent microbial communities that are characterized by one or more dominant microorganisms. The colonization and stabilization of loose sediment is carried out by a microbial assemblage of generalists that prepare the ground for later replacement and succession by specialized microflora. Lithification of microbial mats takes place periodically, mainly during the austral summer. This process is destructive for the microbial community but increases the preservation potential of the stromatolitic structures.

  18. The MATS satellite mission - tomographic perspectives on the mesosphere

    NASA Astrophysics Data System (ADS)

    Christensen, Ole Martin; Gumbel, Jörg; Megner, Linda; Murtagh, Donal P.; Ivchenko, Nickolay

    2016-04-01

    MATS (Mesospheric Airglow/Aerosol Tomography and Spectroscopy) is a Swedish satellite mission scheduled for launch in 2019. MATS science focuses on mesospheric wave activity and noctilucent clouds. Primary measurement targets are O2 Atmospheric band dayglow and nightglow in the near infrared (759-767 nm) and sunlight scattered from noctilucent clouds in the ultraviolet (270-300 nm). While tomography provides horizontally and vertically resolved data, spectroscopy allows analysis in terms of mesospheric composition, temperature and cloud properties. During 2015, the design of the MATS instrument was finalized, and the first complete instrument design will be shown in this presentation. As a part of this work, simulated measurements were performed and inverted using a 3 dimensional tomographic algorithm based on the optimal estimation method. As a result, the first quantitative estimation of the instruments capabilities and performance figures can now be presented, and hence give a more accurate picture of the scientific opportunities that the MATS mission provides.

  19. The Thermal Collector With Varied Glass Covers

    NASA Astrophysics Data System (ADS)

    Luminosu, I.; Pop, N.

    2010-08-01

    The thermal collector with varied glass covers represents an innovation realized in order to build a collector able to reach the desired temperature by collecting the solar radiation from the smallest surface, with the highest efficiency. In the case of the thermal collector with variable cover glasses, the number of the glass plates covering the absorber increases together with the length of the circulation pipe for the working fluid. The thermal collector with varied glass covers compared to the conventional collector better meet user requirements because: for the same temperature increase, has the collecting area smaller; for the same collection area, realizes the highest temperature increase and has the highest efficiency. This works is addressed to researchers in the solar energy and to engineers responsible with air-conditioning systems design or industrial and agricultural products drying.

  20. Durability of a continuous strand mat polymeric composite for automotive structural applications

    SciTech Connect

    Corum, J.M.; McCoy, H.E. Jr.; Ruggles, M.B.; Simpson, W.A. Jr.

    1995-12-31

    A key unanswered question that must be addressed before polymeric composites will be widely used in automotive structural components is their durability. Major durability issues are the effects of cyclic loadings, creep, automotive environments, and low-energy impacts on dimensional stability, strength, and stiffness. The U.S. Department of Energy is sponsoring a project at Oak Ridge National Laboratory to address these issues and to develop, in cooperation with the Automotive Composites Consortium, experimentally based, durability driven, design guidelines. The initial reference material is an isocyanurate reinforced with a continuous strand, swirl glass mat. This paper describes the basic deformation and failure behavior of the reference material, and it presents test results illustrating the property degradations caused by loading, time, and environmental effects. The importance of characterizing and understanding damage and how it leads to failure is also discussed. The results presented are from the initial phases of an ongoing project. The ongoing effort and plans are briefly described.

  1. Some Aspects of the Deformation Response of Swirl-Mat Composites

    SciTech Connect

    Elahi, M.; Weitsman, Y.J.

    1999-10-01

    This report concerns the mechanical response of random glass fiber strand swirl-mat/urethane matrix composite under static and cyclic loads as well as under elevated temperatures and exposure to distilled water. The article presents an extensive amount of experimental data as well as predictions based on a couple damage/viscoelastic constitutive formulation generated to model the specific behavior of the material at hand. Damage evolution relations are derived from an empirical relationship. This work extends previously published results. It is shown that the current model has the capability to predict long-term response on the basis of short-term data and account for time-varying stresses and temperatures.

  2. The biogeochemistry of microbial mats, stromatolites and the ancient biosphere

    NASA Technical Reports Server (NTRS)

    Desmarais, D. J.; Canfield, D. E.

    1991-01-01

    Stromatolites offer an unparalleled geologic record of early life, because they constitute the oldest and most abundant recognizable remains of microbial ecosystems. Microbial mats are living homologs of stromatolites; thus, the physiology of the microbiota as well as the processes which create those features of mats (e.g., biomarker organic compounds, elemental and stable isotopic compositions) which are preserved in the ancient record. Observations of the carbon isotopic composition (delta C-13) of stromatolites and microbial mats were made and are consistent with the hypothesis that atmospheric CO2 concentrations have declined by at least one to two orders of magnitude during the past 2.5 Ga. Whereas delta C-13 values of carbonate carbon average about 0 permil during both the early and mid-Proterozoic, the delta C-13 values of stromatolitic organic matter increase from an average of -35 between 2.0 and 2.6 Ga ago to an average of about -28 about 1.0 Ga ago. Modern microbial mats in hypersaline environments have delta C-13 values typically in the range of -5 to -9, relative to an inorganic bicarbonate source at 0 permil. Both microbial mats and pur cultures of cyanobacteria grown in waters in near equilibrium with current atmospheric CO2 levels exhibit minimal discrimination against C-13. In contrast, hot spring cyanobacterial mats or cyanobacterial cultures grown under higher CO2 levels exhibit substantially greater discrimination. If care is taken to compare modern mats with stromatolites from comparable environments, it might be possible to estimate ancient levels of atmospheric CO2. In modern microbial mats, a tight coupling exists between photosynthetic organic carbon production and subsequent carbon oxidation, mostly by sulfate reduction. The rate of one process fuels a high rate of the other, with much of the sulfate reduction occurring within the same depth interval as oxygenic photosynthesis. Other aspects of this study are presented.

  3. Nitrification and Nitrifying Bacteria in a Coastal Microbial Mat

    PubMed Central

    Fan, Haoxin; Bolhuis, Henk; Stal, Lucas J.

    2015-01-01

    The first step of nitrification, the oxidation of ammonia to nitrite, can be performed by ammonia-oxidizing archaea (AOA) or ammonium-oxidizing bacteria (AOB). We investigated the presence of these two groups in three structurally different types of coastal microbial mats that develop along the tidal gradient on the North Sea beach of the Dutch barrier island Schiermonnikoog. The abundance and transcription of amoA, a gene encoding for the alpha subunit of ammonia monooxygenase that is present in both AOA and AOB, were assessed and the potential nitrification rates in these mats were measured. The potential nitrification rates in the three mat types were highest in autumn and lowest in summer. AOB and AOA amoA genes were present in all three mat types. The composition of the AOA and AOB communities in the mats of the tidal and intertidal stations, based on the diversity of amoA, were similar and clustered separately from the supratidal microbial mat. In all three mats AOB amoA genes were significantly more abundant than AOA amoA genes. The abundance of neither AOB nor AOA amoA genes correlated with the potential nitrification rates, but AOB amoA transcripts were positively correlated with the potential nitrification rate. The composition and abundance of amoA genes seemed to be partly driven by salinity, ammonium, temperature, and the nitrate/nitrite concentration. We conclude that AOB are responsible for the bulk of the ammonium oxidation in these coastal microbial mats. PMID:26648931

  4. Antifouling Electrospun Nanofiber Mats Functionalized with Polymer Zwitterions.

    PubMed

    Kolewe, Kristopher W; Dobosz, Kerianne M; Rieger, Katrina A; Chang, Chia-Chih; Emrick, Todd; Schiffman, Jessica D

    2016-10-06

    In this study, we exploit the excellent fouling resistance of polymer zwitterions and present electrospun nanofiber mats surface functionalized with poly(2-methacryloyloxyethyl phosphorylcholine) (polyMPC). This zwitterionic polymer coating maximizes the accessibility of the zwitterion to effectively limit biofouling on nanofiber membranes. Two facile, scalable methods yielded a coating on cellulose nanofibers: (i) a two-step sequential deposition featuring dopamine polymerization followed by the physioadsorption of polyMPC, and (ii) a one-step codeposition of polydopamine (PDA) with polyMPC. While the sequential and codeposited nanofiber mat assemblies have an equivalent average fiber diameter, hydrophilic contact angle, surface chemistry, and stability, the topography of nanofibers prepared by codeposition were smoother. Protein and microbial antifouling performance of the zwitterion modified nanofiber mats along with two controls, cellulose (unmodified) and PDA coated nanofiber mats were evaluated by dynamic protein fouling and prolonged bacterial exposure. Following 21 days of exposure to bovine serum albumin, the sequential nanofiber mats significantly resisted protein fouling, as indicated by their 95% flux recovery ratio in a water flux experiment, a 300% improvement over the cellulose nanofiber mats. When challenged with two model microbes Escherichia coli and Staphylococcus aureus for 24 h, both zwitterion modifications demonstrated superior fouling resistance by statistically reducing microbial attachment over the two controls. This study demonstrates that, by decorating the surfaces of chemically and mechanically robust cellulose nanofiber mats with polyMPC, we can generate high performance, free-standing nanofiber mats that hold potential in applications where antifouling materials are imperative, such as tissue engineering scaffolds and water purification technologies.

  5. Le matérialisme scientifique

    NASA Astrophysics Data System (ADS)

    Meunier, Jean-François

    2004-03-01

    De nos jours, il arrive quotidiennement aux grands hommes d'avoir à fréquenter d'ignorants mortels épris d'une conviction maladive que la science est la grande responsable de tous les maux du monde. Évidemment sans physique atomique, il n'y aurait pas eu d'Hiroshima et sans révolution industrielle, pas de pollution et etc. Cependant, ces accusations envers le progrès technique sont tout à fait injustes, irréfléchies et, j'irai même jusqu'à dire, irresponsables, puisque le calcul, i.e. la planification, même la plus élémentaire, est ce qui caractérise le mieux, pragmatiquement, la société humaine. À mon avis, les problèmes sociaux tireraient plutôt leur origine de sciences sociales irréalistes, qui, concrètment, inspireraient ou serviraient d'alibis à ceux qui détiennent véritablement le pouvoir. Dans cet article, je tenterai donc de démontrer la meilleure véracité et efficacité du matérialisme scientifique. Cette doctrine, dont Mario Bunge est le plus illustre représentant, s'appuy sur les résultats théoriques et expérimentaux des sciences factuelles ainsi que sur l'exactitude logique des mathématiques, utilisées ici comme langage universel de l'expression des idées. Cette conception philosophique qui s'inspire principalement du modèle des théories physiques, stipule que les réalités sociales sont, comme tout autre réalité, matérielles, mathématisables et représentables comme des systèmes en interaction. En fait, le modèle des physiciens ayant historiquement fait ses preuves en matière de testabilité et de cohérence interne est proposé d'être appliquer aux sciences sociales, aujourd'hui scindées des sciences dites pures sous l'inspiration des pseudo penseurs néo-kantiens, phénoménologiques et post-moderne. Cette nouvelle approche permettrait ainsi d'évoluer plus exactement vers une compréhension des bases sociales et biologiques du comportement humain afin de développer une éthique sans cesse plus r

  6. Absorbent product to absorb fluids. [for collection of human wastes

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multi-layer absorbent product for use in contact with the skin to absorb fluids is discussed. The product utilizes a water pervious facing layer for contacting the skin, overlayed by a first fibrous wicking layer, the wicking layer preferably being of the one-way variety in which fluid or liquid is moved away from the facing layer. The product further includes a first container section defined by inner and outer layer of a water pervious wicking material between which is disposed a first absorbent mass. A second container section defined by inner and outer layers between which is disposed a second absorbent mass and a liquid impermeable/gas permeable layer. Spacesuit applications are discussed.

  7. Methane Production by Microbial Mats Under Low Sulfate Concentrations

    NASA Technical Reports Server (NTRS)

    Bebout, Brad M.; Hoehler, Tori M.; Thamdrup, Bo; Albert, Dan; Carpenter, Steven P.; Hogan, Mary; Turk, Kendra; DesMarais, David J.

    2003-01-01

    Cyanobacterial mats collected in hypersaline salterns were incubated in a greenhouse under low sulfate concentrations ([SO4]) and examined for their primary productivity and emissions of methane and other major carbon species. Atmospheric greenhouse warming by gases such as carbon dioxide and methane must have been greater during the Archean than today in order to account for a record of moderate to warm paleoclemates, despite a less luminous early sun. It has been suggested that decreased levels of oxygen and sulfate in Archean oceans could have significantly stimulated microbial methanogenesis relative to present marine rates, with a resultant increase in the relative importance of methane in maintaining the early greenhouse. We maintained modern microbial mats, models of ancient coastal marine communities, in artificial brine mixtures containing both modern [SO4=] (ca. 70 mM) and "Archean" [SO4] (less than 0.2 mM). At low [SO4], primary production in the mats was essentially unaffected, while rates of sulfate reduction decreased by a factor of three, and methane fluxes increased by up to ten-fold. However, remineralization by methanogenesis still amounted to less than 0.4 % of the total carbon released by the mats. The relatively low efficiency of conversion of photosynthate to methane is suggested to reflect the particular geometry and chemical microenvironment of hypersaline cyanobacterial mats. Therefore, such mats w-ere probably relatively weak net sources of methane throughout their 3.5 Ga history, even during periods of low- environmental levels oxygen and sulfate.

  8. Invasive algal mats degrade coral reef physical habitat quality

    NASA Astrophysics Data System (ADS)

    Martinez, Jonathan A.; Smith, Celia M.; Richmond, Robert H.

    2012-03-01

    Invasive species alter the ecology of marine ecosystems through a variety of mechanisms or combination of mechanisms. This study documented critical physical parameters altered by the invasive red macroalga Gracilaria salicornia in situ, including: reduced irradiance, increased sedimentation, and marked variation in diurnal dissolved oxygen and pH cycles in Kāne'ohe Bay, O'ahu, Hawai'i. Paired studies showed that algal mats reduced irradiance by 99% and doubled sediment accumulation. Several mats developed hypoxia and hyperoxia in the extreme minima and maxima, though there was no statistical difference detected in the mean or the variability of dissolved oxygen between different 30 min time points of 24 h cycles between algal mat-open reef pairs. The algal mat significantly acidified the water under the algal mat by decreasing pH by 0.10-0.13 pH units below open reef pH. A minimum of pH 7.47 occurred between 14 and 19 h after sunrise. Our combined results suggest that mats of G. salicornia can alter various physical parameters on a fine scale and time course not commonly detected. These changes in parameters give insight into the underlying basis for negative impact, and suggest new ways in which the presence of invasive species leads to decline of coral reef ecosystems.

  9. Cyanobacterial reuse of extracellular organic carbon in microbial mats

    PubMed Central

    Stuart, Rhona K; Mayali, Xavier; Lee, Jackson Z; Craig Everroad, R; Hwang, Mona; Bebout, Brad M; Weber, Peter K; Pett-Ridge, Jennifer; Thelen, Michael P

    2016-01-01

    Cyanobacterial organic matter excretion is crucial to carbon cycling in many microbial communities, but the nature and bioavailability of this C depend on unknown physiological functions. Cyanobacteria-dominated hypersaline laminated mats are a useful model ecosystem for the study of C flow in complex communities, as they use photosynthesis to sustain a more or less closed system. Although such mats have a large C reservoir in the extracellular polymeric substances (EPSs), the production and degradation of organic carbon is not well defined. To identify extracellular processes in cyanobacterial mats, we examined mats collected from Elkhorn Slough (ES) at Monterey Bay, California, for glycosyl and protein composition of the EPS. We found a prevalence of simple glucose polysaccharides containing either α or β (1,4) linkages, indicating distinct sources of glucose with differing enzymatic accessibility. Using proteomics, we identified cyanobacterial extracellular enzymes, and also detected activities that indicate a capacity for EPS degradation. In a less complex system, we characterized the EPS of a cyanobacterial isolate from ES, ESFC-1, and found the extracellular composition of biofilms produced by this unicyanobacterial culture were similar to that of natural mats. By tracing isotopically labeled EPS into single cells of ESFC-1, we demonstrated rapid incorporation of extracellular-derived carbon. Taken together, these results indicate cyanobacteria reuse excess organic carbon, constituting a dynamic pool of extracellular resources in these mats. PMID:26495994

  10. Photosynthate Partitioning and Fermentation in Hot Spring Microbial Mat Communities

    PubMed Central

    Nold, S. C.; Ward, D. M.

    1996-01-01

    Patterns of (sup14)CO(inf2) incorporation into molecular components of the thermophilic cyanobacterial mat communities inhabiting hot springs located in Yellowstone National Park and Synechococcus sp. strain C1 were investigated. Exponentially growing Synechococcus sp. strain C1 partitioned the majority of incorporated (sup14)CO(inf2) into protein, low-molecular-weight metabolites, and lipid fractions (45, 22, and 18% of total incorporated carbon, respectively). In contrast, mat cores from various hot springs predominantly accumulated polyglucose during periods of illumination (between 77 and 85% of total incorporated (sup14)CO(inf2)). Although photosynthetically active, mat photoautotrophs do not appear to be rapidly growing, since we also detected only limited synthesis of macromolecules associated with growth (i.e., protein and rRNA). To test the hypothesis that polysaccharide reserves are fermented in situ under the dark anaerobic conditions cyanobacterial mats experience at night, mat cores were prelabeled with (sup14)CO(inf2) under illuminated conditions and then transferred to dark anaerobic conditions. Radiolabel in the polysaccharide fraction decreased by 74.7% after 12 h, of which 58.5% was recovered as radiolabeled acetate, CO(inf2), and propionate. These results indicate tightly coupled carbon fixation and fermentative processes and the potential for significant transfer of carbon from primary producers to heterotrophic members of these cyanobacterial mat communities. PMID:16535472

  11. Mechanical behavior of ultralong multiwalled carbon nanotube mats

    NASA Astrophysics Data System (ADS)

    Deck, Christian P.; Flowers, Jason; McKee, Gregg S. B.; Vecchio, Kenneth

    2007-01-01

    Carbon nanotubes (CNTs) have been a subject of great interest partially due to their potential for exceptional material properties. Improvements in synthesis methods have facilitated the production of ultralong CNT mats, with lengths in the millimeter range. The increased length of these ultralong mats has, in return, opened the way to greater flexibility to probe their mechanical response. In this work, mats of dense, well-aligned, multiwalled carbon nanotubes were grown with a vapor-phase chemical vapor deposition technique using ferrocene and benzene as reactants, and subsequently tested in both tension and compression using two methods, in a thermomechanical analyzer and in situ inside a scanning electron microscope. In compression, measured stiffness was very low, due to buckling of the nanotubes. In tension, the nanotube mats behaved considerably stiffer; however, they were still more compliant than expected for nanotubes (˜1TPa). Analysis of both the growth method used and the nanotube mat fracture surface suggests that the mats grown in this method are not composed of continuous nanotubes and their strengths actually closely match those of woven nanotube yarns and ropes.

  12. Glass as a waste form for the immobilization of plutonium

    SciTech Connect

    Bates, J.K.; Ellison, A.J.G.; Emery, J.W.; Hoh, J.C.

    1995-12-31

    Several alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkali-tin-silicate glass.

  13. An introduction to absorbent dressings.

    PubMed

    Jones, Menna Lloyd

    2014-12-01

    Exudate bathes the wound bed with a serous fluid that contains essential components that promote wound healing. However, excess exudate is often seen as a challenge for clinicians. Absorbent dressings are often used to aid in the management of exudate, with the aim of providing a moist but unmacerated environment. With so many different types of absorbent dressings available today-alongside making a holistic assessment-it is essential that clinicians also have the knowledge and skill to select the most appropriate absorbent dressing for a given patient.

  14. Self-Regulating Shock Absorber

    NASA Technical Reports Server (NTRS)

    Wesselski, Clarence J.

    1995-01-01

    Mechanical shock absorber keeps frictional damping force within tolerable limit. Its damping force does not increase with coefficient of friction between energy-absorbing components; rather, frictional damping force varies only slightly. Relatively insensitive to manufacturing variations and environmental conditions altering friction. Does not exhibit high breakaway friction and consequent sharp increase followed by sharp decrease in damping force at beginning of stroking. Damping force in absorber does not vary appreciably with speed of stroking. In addition, not vulnerable to leakage of hydraulic fluid.

  15. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    NASA Astrophysics Data System (ADS)

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, Youngpak

    2015-09-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  16. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets

    PubMed Central

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-01-01

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet–height and diameter– and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials. PMID:26354891

  17. Metamaterial Absorber for Electromagnetic Waves in Periodic Water Droplets.

    PubMed

    Yoo, Young Joon; Ju, Sanghyun; Park, Sang Yoon; Ju Kim, Young; Bong, Jihye; Lim, Taekyung; Kim, Ki Won; Rhee, Joo Yull; Lee, YoungPak

    2015-09-10

    Perfect metamaterial absorber (PMA) can intercept electromagnetic wave harmful for body in Wi-Fi, cell phones and home appliances that we are daily using and provide stealth function that military fighter, tank and warship can avoid radar detection. We reported new concept of water droplet-based PMA absorbing perfectly electromagnetic wave with water, an eco-friendly material which is very plentiful on the earth. If arranging water droplets with particular height and diameter on material surface through the wettability of material surface, meta-properties absorbing electromagnetic wave perfectly in GHz wide-band were shown. It was possible to control absorption ratio and absorption wavelength band of electromagnetic wave according to the shape of water droplet-height and diameter- and apply to various flexible and/or transparent substrates such as plastic, glass and paper. In addition, this research examined how electromagnetic wave can be well absorbed in water droplets with low electrical conductivity unlike metal-based metamaterials inquiring highly electrical conductivity. Those results are judged to lead broad applications to variously civilian and military products in the future by providing perfect absorber of broadband in all products including transparent and bendable materials.

  18. Regulation of electron transfer processes affects phototrophic mat structure and activity

    PubMed Central

    Ha, Phuc T.; Renslow, Ryan S.; Atci, Erhan; Reardon, Patrick N.; Lindemann, Stephen R.; Fredrickson, James K.; Call, Douglas R.; Beyenal, Haluk

    2015-01-01

    Phototrophic microbial mats are among the most diverse ecosystems in nature. These systems undergo daily cycles in redox potential caused by variations in light energy input and metabolic interactions among the microbial species. In this work, solid electrodes with controlled potentials were placed under mats to study the electron transfer processes between the electrode and the microbial mat. The phototrophic microbial mat was harvested from Hot Lake, a hypersaline, epsomitic lake located near Oroville (Washington, USA). We operated two reactors: graphite electrodes were polarized at potentials of -700 mVAg/AgCl [cathodic (CAT) mat system] and +300 mVAg/AgCl [anodic (AN) mat system] and the electron transfer rates between the electrode and mat were monitored. We observed a diel cycle of electron transfer rates for both AN and CAT mat systems. Interestingly, the CAT mats generated the highest reducing current at the same time points that the AN mats showed the highest oxidizing current. To characterize the physicochemical factors influencing electron transfer processes, we measured depth profiles of dissolved oxygen (DO) and sulfide in the mats using microelectrodes. We further demonstrated that the mat-to-electrode and electrode-to-mat electron transfer rates were light- and temperature-dependent. Using nuclear magnetic resonance (NMR) imaging, we determined that the electrode potential regulated the diffusivity and porosity of the microbial mats. Both porosity and diffusivity were higher in the CAT mats than in the AN mats. We also used NMR spectroscopy for high-resolution quantitative metabolite analysis and found that the CAT mats had significantly higher concentrations of osmoprotectants such as betaine and trehalose. Subsequently, we performed amplicon sequencing across the V4 region of the 16S rRNA gene of incubated mats to understand the impact of electrode potential on microbial community structure. These data suggested that variation in the

  19. The possibility of E-glass woven roving as reinforcement of GFRP composite sheet roof

    NASA Astrophysics Data System (ADS)

    Setyanto, Djoko

    2016-03-01

    The 1.25 mm thickness of opaque glass fiber reinforced polymer (GFRP) composite sheet roof that is produced by an Indonesia company at Tangerang, consists of two layers of 300 g/m2 E-glass chopped strand mat as reinforcement and unsaturated polyester resin as matrix. A layer of 300 g/m2 E-glass chopped strand mat is replaced by a layer of 400 g/m2 E-glass woven roving as reinforcement to study the possibility use as sheet roof material. The properties of the two samples of GFRP composite materials were compared. Barcol hardness and flexure strength of the two samples relatively not significance change. Tensile strength and elastic modulus of the new sample which contains a layer of woven roving reinforcement is greater than the other one. On the other hand the waviness of the new sample is greater, but cheaper. In general, a layer of E-glass woven roving and a layer of E-glass chopped strand mat can be considered as an alternative reinforcement of two layers reinforcement of GFRP composite material of sheet roof.

  20. ERB master archival tape specification no. T 134081 ERB MAT, revision 1

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The Earth radiation budget (ERB)MAT tapes are generated by the ERB MATGEN software using the IBM 3081 computer system operated by the Science and Applications Computer Center at Goddard Space Flight Center. All MAT's are 9-track and MAT data are in ascending time order. The gross tape format for NIMBUS year-1 and year-2 MAT's is different from the format of MAT's starting with year-3. The MATs from the first two years are to contain one day's worth of data while all other MATs are to contain multiple day's worth of data stacked onto the tapes.

  1. Spontaneous emission and absorber theory

    NASA Astrophysics Data System (ADS)

    Pegg, David T.

    1997-01-01

    One of the long term interests of George Series was the construction of a theory of spontaneous emission which does not involve field quantisation. His approach was written in terms of atomic operators only and he drew a parallel with the Wheeler-Feynman absorber theory of radiation. By making a particular extra postulate, he was able to obtain the correct spontaneous emission rate and the Lamb shift reasonably simply and directly. An examination of his approach indicates that this postulate is physically reasonable and the need for it arises because quantisation in his theory occurs after the response of the absorber has been accounted for by means of the radiative reaction field. We review briefly an alternative absorber theory approach to spontaneous emission based on the direct action between the emitting atom and a quantised absorber, and outline some applications to more recent effects of interest in quantum optics.

  2. Guided tissue regeneration. Absorbable barriers.

    PubMed

    Wang, H L; MacNeil, R L

    1998-07-01

    Over the past 15 years, techniques aimed at regeneration of lost periodontal tissue have become widely used and accepted in clinical practice. Among these techniques are those which use the principles of guided tissue regeneration (GTR), wherein barriers (i.e., membranes) are used to control cell and tissue repopulation of the periodontal wound. A variety of non-absorbable and absorbable barriers have been developed and used for this purpose, with a trend in recent years toward increased use of absorbable GTR materials. This article describes the evolution of absorbable barrier materials and overview materials available for clinical use today. In addition, advantages and disadvantages of these materials are discussed, as well as possible new developments in barrier-based GTR therapy.

  3. Solar power absorption in a glass tube

    NASA Technical Reports Server (NTRS)

    Williams, Michael D.

    1987-01-01

    The optics of a glass tube to be used in near-Earth space at the focus of a solar concentrator has been examined, and an equation for the power absorbed from multiple-reflected light beams in the tube wall has been developed. The equation has been used to calculate the power absorbed by a highly transmissive form of fused silica. The equilibrium temperature reached by the tube with only radiative cooling has also been examined, and it shows a significant rise with large solar concentrations. The results apply specifically to cylindrical containment vessels for space-based solar-pumped lasers and generally to any similarly irradiated tubes.

  4. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, W.H.

    1984-10-16

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system. 9 figs.

  5. Countercurrent flow absorber and desorber

    DOEpatents

    Wilkinson, William H.

    1984-01-01

    Countercurrent flow absorber and desorber devices are provided for use in absorption cycle refrigeration systems and thermal boosting systems. The devices have increased residence time and surface area resulting in improved heat and mass transfer characteristics. The apparatuses may be incorporated into open cycle thermal boosting systems in which steam serves both as the refrigerant vapor which is supplied to the absorber section and as the supply of heat to drive the desorber section of the system.

  6. Angiogenic effects of borate glass microfibers in a rodent model.

    PubMed

    Lin, Yinan; Brown, Roger F; Jung, Steven B; Day, Delbert E

    2014-12-01

    The primary objective of this research was to evaluate the use of bioactive borate-based glass microfibers for angiogenesis in soft tissue repair applications. The effect of these fibers on growth of capillaries and small blood vessels was compared to that of 45S5 silica glass microfibers and sham implant controls. Compressed mats of three types of glass microfibers were implanted subcutaneously in rats and tissues surrounding the implant sites histologically evaluated 2-4 weeks post surgery. Bioactive borate glass 13-93B3 supplemented with 0.4 wt % copper promoted extensive angiogenesis as compared to silica glass microfibers and sham control tissues. The angiogenic responses suggest the copper-containing 13-93B3 microfibers may be effective for treating chronic soft tissue wounds. A second objective was to assess the possible systemic cytotoxicity of dissolved borate ions and other materials released from implanted borate glass microfibers. Cytotoxicity was assessed via histological evaluation of kidney tissue collected from animals 4 weeks after subcutaneously implanting high amounts of the borate glass microfibers. The evaluation of the kidney tissue from these animals showed no evidence of chronic histopathological changes in the kidney. The overall results indicate the borate glass microfibers are safe and effective for soft tissue applications.

  7. Perfect selective metamaterial solar absorbers.

    PubMed

    Wang, Hao; Wang, Liping

    2013-11-04

    In this work, we numerically investigate the radiative properties of metamaterial nanostructures made of two-dimensional tungsten gratings on a thin dielectric spacer and an opaque tungsten film from UV to mid-infrared region as potential selective solar absorbers. The metamaterial absorber with single-sized tungsten patches exhibits high absorptance in the visible and near-infrared region due to several mechanisms such as surface plasmon polaritons, magnetic polaritons, and intrinsic bandgap absorption of tungsten. Geometric effects on the resonance wavelengths and the absorptance spectra are studied, and the physical mechanisms are elucidated in detail. The absorptance could be further enhanced in a broader spectral range with double-sized metamaterial absorbers. The total solar absorptance of the optimized metamaterial absorbers at normal incidence could be more than 88%, while the total emittance is less than 3% at 100°C, resulting in total photon-to-heat conversion efficiency of 86% without any optical concentration. Moreover, the metamaterial solar absorbers exhibit quasi-diffuse behaviors as well as polarization independence. The results here will facilitate the design of novel highly efficient solar absorbers to enhance the performance of various solar energy conversion systems.

  8. Test of lead glass shower counters

    SciTech Connect

    Kawabata, S.; Ogawa, K.; Sugahara, R.; Sumiyoshi, T.; Takahashi, K.; Awaji, N.; Hayashii, H.; Iwata, S.; Gearhart, R.A.; Miyamoto, A.

    1983-10-01

    Lead glass counters made of wedge shaped blocks of SF6 were tested with positrons at SLAC. The beam energy ranged from 2 to 17.5 GeV. Energy dependence and beam position dependence of pulse height and energy resolution were studied with lead glass blocks of various lengths. The effect of a BK-7 light guide on pulse height was clearly observed. Degradation of the energy resolution due to aluminum absorbers of various lengths was investigated. A mesh type photomultiplier was also tested.

  9. Photosynthetic Microbial Mats are Exemplary Sources of Diverse Biosignatures (Invited)

    NASA Astrophysics Data System (ADS)

    Des Marais, D. J.; Jahnke, L. L.

    2013-12-01

    Marine cyanobacterial microbial mats are widespread, compact, self-contained ecosystems that create diverse biosignatures and have an ancient fossil record. Within the mats, oxygenic photosynthesis provides organic substrates and O2 to the community. Both the absorption and scattering of light change the intensity and spectral composition of incident radiation as it penetrates a mat. Some phototrophs utilize infrared light near the base of the photic zone. A mat's upper layers can become highly reduced and sulfidic at night. Counteracting gradients of O2 and sulfide shape the chemical environment and provide daily-contrasting microenvironments separated on a scale of a few mm. Radiation hazards (UV, etc.), O2 and sulfide toxicity elicit motility and other physiological responses. This combination of benefits and hazards of light, O2 and sulfide promotes the allocation of various essential mat processes between light and dark periods and to various depths in the mat. Associated nonphotosynthetic communities, including anaerobes, strongly influence many of the ecosystem's overall characteristics, and their processes affect any biosignatures that enter the fossil record. A biosignature is an object, substance and/or pattern whose origin specifically requires a biological agent. The value of a biosignature depends not only on the probability of life creating it, but also on the improbability of nonbiological processes producing it. Microbial mats create biosignatures that identify particular groups of organisms and also reveal attributes of the mat ecosystem. For example, branched hydrocarbons and pigments can be diagnostic of cyanobacteria and other phototrophic bacteria, and isoprenoids can indicate particular groups of archea. Assemblages of lipid biosignatures change with depth due to changes in microbial populations and diagenetic transformations of organic matter. The 13C/12C values of organic matter and carbonates reflect isotopic discrimination by particular

  10. Sulphur cycling in a Neoarchaean microbial mat.

    PubMed

    Meyer, N R; Zerkle, A L; Fike, D A

    2017-01-27

    Multiple sulphur (S) isotope ratios are powerful proxies to understand the complexity of S biogeochemical cycling through Deep Time. The disappearance of a sulphur mass-independent fractionation (S-MIF) signal in rocks <~2.4 Ga has been used to date a dramatic rise in atmospheric oxygen levels. However, intricacies of the S-cycle before the Great Oxidation Event remain poorly understood. For example, the isotope composition of coeval atmospherically derived sulphur species is still debated. Furthermore, variation in Archaean pyrite δ(34) S values has been widely attributed to microbial sulphate reduction (MSR). While petrographic evidence for Archaean early-diagenetic pyrite formation is common, textural evidence for the presence and distribution of MSR remains enigmatic. We combined detailed petrographic and in situ, high-resolution multiple S-isotope studies (δ(34) S and Δ(33) S) using secondary ion mass spectrometry (SIMS) to document the S-isotope signatures of exceptionally well-preserved, pyritised microbialites in shales from the ~2.65-Ga Lokammona Formation, Ghaap Group, South Africa. The presence of MSR in this Neoarchaean microbial mat is supported by typical biogenic textures including wavy crinkled laminae, and early-diagenetic pyrite containing <26‰ μm-scale variations in δ(34) S and Δ(33) S = -0.21 ± 0.65‰ (±1σ). These large variations in δ(34) S values suggest Rayleigh distillation of a limited sulphate pool during high rates of MSR. Furthermore, we identified a second, morphologically distinct pyrite phase that precipitated after lithification, with δ(34) S = 8.36 ± 1.16‰ and Δ(33) S = 5.54 ± 1.53‰ (±1σ). We propose that the S-MIF signature of this secondary pyrite does not reflect contemporaneous atmospheric processes at the time of deposition; instead, it formed by the influx of later-stage sulphur-bearing fluids containing an inherited atmospheric S-MIF signal and/or from magnetic isotope effects during

  11. GlassForm

    SciTech Connect

    2011-09-16

    GlassForm is a software tool for generating preliminary waste glass formulas for a given waste stream. The software is useful because it reduces the number of verification melts required to develop a suitable additive composition. The software includes property models that calculate glass properties of interest from the chemical composition of the waste glass. The software includes property models for glass viscosity, electrical conductivity, glass transition temperature, and leach resistance as measured by the 7-day product consistency test (PCT).

  12. Strength of inorganic glass

    SciTech Connect

    Kurkjian, C.R.

    1985-01-01

    This book presents information on the following topics: a look at the history of glass strength; atomistic theory of fracture; surface chemistry in relation to the strength and fracture of silicate glasses; high-speed photographic investigations of the dynamic localized loading of some oxide glasses; a correction for measurements of contact area using Newton's rings; envionmentally enhanced crack growth; fatigue in glass; behavior of flaws in fused silica fibers; fracture toughness of chalcogenide glasses and glass-ceramics; fracture analysis of glass surfaces; and fracture mechanics parameters for glasses - a compilation and correlation.

  13. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    SciTech Connect

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  14. IMPACT STRENGTH OF GLASS AND GLASS CERAMIC

    SciTech Connect

    Bless, S.; Tolman, J.

    2009-12-28

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  15. Physiological and Metagenomic Analyses of Microbial Mats Involved in Self-Purification of Mine Waters Contaminated with Heavy Metals

    PubMed Central

    Drewniak, Lukasz; Krawczyk, Pawel S.; Mielnicki, Sebastian; Adamska, Dorota; Sobczak, Adam; Lipinski, Leszek; Burec-Drewniak, Weronika; Sklodowska, Aleksandra

    2016-01-01

    Two microbial mats found inside two old (gold and uranium) mines in Zloty Stok and Kowary located in SW Poland seem to form a natural barrier that traps heavy metals leaking from dewatering systems. We performed complex physiological and metagenomic analyses to determine which microorganisms are the main driving agents responsible for self-purification of the mine waters and identify metabolic processes responsible for the observed features. SEM and energy dispersive X-ray microanalysis showed accumulation of heavy metals on the mat surface, whereas, sorption experiments showed that neither microbial mats were completely saturated with heavy metals present in the mine waters, indicating that they have a large potential to absorb significant quantities of metal. The metagenomic analysis revealed that Methylococcaceae and Methylophilaceae families were the most abundant in both communities, moreover, it strongly suggest that backbones of both mats were formed by filamentous bacteria, such as Leptothrix, Thiothrix, and Beggiatoa. The Kowary bacterial community was enriched with the Helicobacteraceae family, whereas the Zloty Stok community consist mainly of Sphingomonadaceae, Rhodobacteraceae, and Caulobacteraceae families. Functional (culture-based) and metagenome (sequence-based) analyses showed that bacteria involved in immobilization of heavy metals, rather than those engaged in mobilization, were the main driving force within the analyzed communities. In turn, a comparison of functional genes revealed that the biofilm formation and heavy metal resistance (HMR) functions are more desirable in microorganisms engaged in water purification than the ability to utilize heavy metals in the respiratory process (oxidation-reduction). These findings provide insight on the activity of bacteria leading, from biofilm formation to self-purification, of mine waters contaminated with heavy metals. PMID:27559332

  16. Microcosm experiments of oil degradation by microbial mats.

    PubMed

    de Oteyza, Tirso García; Grimalt, Joan O; Llirós, Marc; Esteve, Isabel

    2006-03-15

    Several microcosm experiments were run in parallel to evaluate the efficiency of microbial mats for crude oil degradation as compared with physico-chemical weathering. The oils used in the experiments constituted representative examples of those currently used for commercial purposes. One was aliphatic and of low viscosity (33.4 American Petroleum Institute degrees, degrees API) and the other was predominantly aromatic, with high sulphur content (ca. 2.7%) and viscosity (16.6 degrees API). After crude oil introduction, the microcosms were kept under cyclic changes in water level to mimic coastal tidal movements. The transformations observed showed that water weathering leads to more effective and rapid elimination of low molecular weight hydrocarbons than microbial mat metabolism, e.g. n-alkanes with chain length shorter than n-pentadecane or n-heptadecane, regular isoprenoid hydrocarbons with chain length lower than C16 or C18 or lower molecular weight naphthalenes. Microbial mats preserved these hydrocarbons from volatilization and water washing. However, hydrocarbons of lower volatility such as the C24-C30 n-alkanes or containing nitrogen atoms, e.g. carbazoles, were eliminated in higher proportion by microbial mats than by water weathering. The strong differences in composition between the two oils used for the experiments were also reflected in significant differences between water weathering and microbial mat biodegradation. Higher oil viscosity seemed to hinder the former but not the later.

  17. Stress-strain dependence for soy-protein nanofiber mats

    NASA Astrophysics Data System (ADS)

    Khansari, S.; Sinha-Ray, S.; Yarin, A. L.; Pourdeyhimi, B.

    2012-02-01

    Soy protein/nylon 6 monolithic and core-shell nanofibers were solution-blown and collected on a rotating drum as fiber mats. Tensile tests of rectangular strips of these mats revealed their stress-strain dependences. These dependences were linear at low strains which correspond to their elastic behavior. Then, a plastic-like nonlinearity sets in, which is followed by catastrophic rupture. Parameters such as Young's modulus, yield stress, and specific strain energy were measured. The results were rationalized in the framework of the phenomenological elastic-plastic model, as well as a novel micromechanical model (the latter attributes plasticity to bond rapture between the individual overstressed fibers in the mat). Besides, the effects of stretching history, rate of stretching, and winding velocity of the collector drum on the strength-related parameters are studied. The results for soy protein/nylon 6 nanofiber mats are also compared to those for solution blown pure nylon 6 mats, which were produced and tested in the same way.

  18. Angiosperm phylogeny based on matK sequence information.

    PubMed

    Hilu, Khidir W; Borsch, Thomas; Müller, Kai; Soltis, Douglas E; Soltis, Pamela S; Savolainen, Vincent; Chase, Mark W; Powell, Martyn P; Alice, Lawrence A; Evans, Rodger; Sauquet, Hervé; Neinhuis, Christoph; Slotta, Tracey A B; Rohwer, Jens G; Campbell, Christopher S; Chatrou, Lars W

    2003-12-01

    Plastid matK gene sequences for 374 genera representing all angiosperm orders and 12 genera of gymnosperms were analyzed using parsimony (MP) and Bayesian inference (BI) approaches. Traditionally, slowly evolving genomic regions have been preferred for deep-level phylogenetic inference in angiosperms. The matK gene evolves approximately three times faster than the widely used plastid genes rbcL and atpB. The MP and BI trees are highly congruent. The robustness of the strict consensus tree supercedes all individual gene analyses and is comparable only to multigene-based phylogenies. Of the 385 nodes resolved, 79% are supported by high jackknife values, averaging 88%. Amborella is sister to the remaining angiosperms, followed by a grade of Nymphaeaceae and Austrobaileyales. Bayesian inference resolves Amborella + Nymphaeaceae as sister to the rest, but with weak (0.42) posterior probability. The MP analysis shows a trichotomy sister to the Austrobaileyales representing eumagnoliids, monocots + Chloranthales, and Ceratophyllum + eudicots. The matK gene produces the highest internal support yet for basal eudicots and, within core eudicots, resolves a crown group comprising Berberidopsidaceae/Aextoxicaceae, Santalales, and Caryophyllales + asterids. Moreover, matK sequences provide good resolution within many angiosperm orders. Combined analyses of matK and other rapidly evolving DNA regions with available multigene data sets have strong potential to enhance resolution and internal support in deep level angiosperm phylogenetics and provide additional insights into angiosperm evolution.

  19. Documentation generator application for MatLab source codes

    NASA Astrophysics Data System (ADS)

    Niton, B.; Pozniak, K. T.; Romaniuk, R. S.

    2011-06-01

    The UML, which is a complex system modeling and description technology, has recently been expanding its uses in the field of formalization and algorithmic approach to such systems like multiprocessor photonic, optoelectronic and advanced electronics carriers; distributed, multichannel measurement systems; optical networks, industrial electronics, novel R&D solutions. The paper describes a realization of an application for documenting MatLab source codes. There are presented own novel solution based on Doxygen program which is available on the free license, with accessible source code. The used supporting tools for parser building were Bison and Flex. There are presented the practical results of the documentation generator. The program was applied for exemplary MatLab codes. The documentation generator application is used for design of large optoelectronic and electronic measurement and control systems. The paper consists of three parts which describe the following components of the documentation generator for photonic and electronic systems: concept, MatLab application and VHDL application. This is part two which describes the MatLab application. MatLab is used for description of the measured phenomena.

  20. Counting viruses and bacteria in photosynthetic microbial mats.

    PubMed

    Carreira, Cátia; Staal, Marc; Middelboe, Mathias; Brussaard, Corina P D

    2015-03-01

    Viral abundances in benthic environments are the highest found in aquatic systems. Photosynthetic microbial mats represent benthic environments with high microbial activity and possibly high viral densities, yet viral abundances have not been examined in such systems. Existing extraction procedures typically used in benthic viral ecology were applied to the complex matrix of microbial mats but were found to inefficiently extract viruses. Here, we present a method for extraction and quantification of viruses from photosynthetic microbial mats using epifluorescence microscopy (EFM) and flow cytometry (FCM). A combination of EDTA addition, probe sonication, and enzyme treatment applied to a glutaraldehyde-fixed sample resulted in a substantially higher viral (5- to 33-fold) extraction efficiency and reduced background noise compared to previously published methods. Using this method, it was found that in general, intertidal photosynthetic microbial mats harbor very high viral abundances (2.8 × 10(10) ± 0.3 × 10(10) g(-1)) compared with benthic habitats (10(7) to 10(9) g(-1)). This procedure also showed 4.5- and 4-fold-increased efficacies of extraction of viruses and bacteria, respectively, from intertidal sediments, allowing a single method to be used for the microbial mat and underlying sediment.

  1. Mating-type genes and MAT switching in Saccharomyces cerevisiae.

    PubMed

    Haber, James E

    2012-05-01

    Mating type in Saccharomyces cerevisiae is determined by two nonhomologous alleles, MATa and MATα. These sequences encode regulators of the two different haploid mating types and of the diploids formed by their conjugation. Analysis of the MATa1, MATα1, and MATα2 alleles provided one of the earliest models of cell-type specification by transcriptional activators and repressors. Remarkably, homothallic yeast cells can switch their mating type as often as every generation by a highly choreographed, site-specific homologous recombination event that replaces one MAT allele with different DNA sequences encoding the opposite MAT allele. This replacement process involves the participation of two intact but unexpressed copies of mating-type information at the heterochromatic loci, HMLα and HMRa, which are located at opposite ends of the same chromosome-encoding MAT. The study of MAT switching has yielded important insights into the control of cell lineage, the silencing of gene expression, the formation of heterochromatin, and the regulation of accessibility of the donor sequences. Real-time analysis of MAT switching has provided the most detailed description of the molecular events that occur during the homologous recombinational repair of a programmed double-strand chromosome break.

  2. Electrospun chitosan/polyvinyl alcohol nanofibre mats for wound healing.

    PubMed

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2014-04-01

    Chitosan (CS) aqueous salt blended with polyvinyl alcohol (PVA) nanofibre mats was prepared by electrospinning. CS was dissolved with hydroxybenzotriazole (HOBt), thiamine pyrophosphate (TPP) and ethylenediaminetetraacetic acid (EDTA) in distilled water without the use of toxic or hazardous solvents. The CS aqueous salts were blended with PVA at different weight ratios, and the effect of the solution ratios was investigated. The morphologies and mechanical and swelling properties of the generated fibres were analysed. Indirect cytotoxicity studies indicated that the CS/PVA nanofibre mats were non-toxic to normal human fibroblast cells. The CS-HOBt/PVA and CS-EDTA/PVA nanofibre mats demonstrated satisfactory antibacterial activity against both gram-positive and gram-negative bacteria, and an in vivo wound healing test showed that the CS-EDTA/PVA nanofibre mats performed better than gauze in decreasing acute wound size during the first week after tissue damage. In conclusion, the biodegradable, biocompatible and antibacterial CS-EDTA/PVA nanofibre mats have potential for use as wound dressing materials.

  3. Mushroom plasmonic metamaterial infrared absorbers

    SciTech Connect

    Ogawa, Shinpei Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-26

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF{sub 2} etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  4. Mushroom plasmonic metamaterial infrared absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Hata, Hisatoshi; Uetsuki, Mitsuharu; Misaki, Koji; Kimata, Masafumi

    2015-01-01

    There has been a considerable amount of interest in the development of various types of electromagnetic wave absorbers for use in different wavelength ranges. In particular, infrared (IR) absorbers with wavelength selectivity can be applied to advanced uncooled IR sensors, which would be capable of identifying objects through their radiation spectrum. In the present study, mushroom plasmonic metamaterial absorbers (MPMAs) for the IR wavelength region were designed and fabricated. The MPMAs consist of a periodic array of thin metal micropatches connected to a thin metal plate with narrow silicon (Si) posts. A Si post height of 200 nm was achieved by isotropic XeF2 etching of a thin Si layer sandwiched between metal plates. This fabrication procedure is relatively simple and is consistent with complementary metal oxide semiconductor technology. The absorption spectra of the fabricated MPMAs were experimentally measured. In addition, theoretical calculations of their absorption properties were conducted using rigorous coupled wave analysis. Both the calculated and measured absorbance results demonstrated that these MPMAs can realize strong selective absorption at wavelengths beyond the period of the array by varying the micropatch width. Absorbance values greater than 90% were achieved. Dual- or single-mode absorption can also be selected by varying the width of the Si posts. Pixel structures using such MPMAs could be used as high responsivity, high resolution and fast uncooled IR sensors.

  5. Additive manufacturing of RF absorbers

    NASA Astrophysics Data System (ADS)

    Mills, Matthew S.

    The ability of additive manufacturing techniques to fabricate integrated electromagnetic absorbers tuned for specific radio frequency bands within structural composites allows for unique combinations of mechanical and electromagnetic properties. These composites and films can be used for RF shielding of sensitive electromagnetic components through in-plane and out-of-plane RF absorption. Structural composites are a common building block of many commercial platforms. These platforms may be placed in situations in which there is a need for embedded RF absorbing properties along with structural properties. Instead of adding radar absorbing treatments to the external surface of existing structures, which adds increased size, weight and cost; it could prove to be advantageous to integrate the microwave absorbing properties directly into the composite during the fabrication process. In this thesis, a method based on additive manufacturing techniques of composites structures with prescribed electromagnetic loss, within the frequency range 1 to 26GHz, is presented. This method utilizes screen printing and nScrypt micro dispensing to pattern a carbon based ink onto low loss substrates. The materials chosen for this study will be presented, and the fabrication technique that these materials went through to create RF absorbing structures will be described. The calibration methods used, the modeling of the RF structures, and the applications in which this technology can be utilized will also be presented.

  6. Carbon Absorber Retrofit Equipment (CARE)

    SciTech Connect

    Klein, Eric

    2015-12-23

    During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO2) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO2 removal was achieved with greater than 95% CO2product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO2 captured from a sub-critical PC plant.

  7. AN HYBRID GLASS/HEMP FIBERS SOLUTION FRP PIPES: TECHNICAL AND ECONOMIC ADVANTAGES OF HAND LAY UP VS LIGHT RTM

    SciTech Connect

    Cicala, G.; Cristaldi, G.; Recca, G.; Ziegmann, G.; ElSabbagh, A.; Dickert, M.

    2008-08-28

    The aim of the present research was to investigate the replacement of glass fibers with hemp fibers for applications in the piping industry. The choice of hemp fibers was mainly related to the needs, expressed by some companies operating in this sector, for cost reduction without adversely reducing the performances of the pipes. Two processing techniques, namely hand lay up and light RTM, were evaluated. The pipe selected for the study was a curved fitting (90 deg.) flanged at both ends. The fitting must withstand an internal pressure of 10 bar and the presence of acid aqueous solutions. The original lay-up used to build the pipe is a sequence of C-glass, glass mats and glass fabric. Commercial epoxy vinyl ester resin was used as thermoset matrix.Hemp fibers mats were selected as potential substitute of glass fibers mats because of their low cost and ready availability from different commercial sources. The data obtained from the mechanical characterization were used to define a favorable design of the pipe using hemp mats as internal layer. The proposed design for the fittings allowed for a cost reduction of about 24% and a weight saving of about 23% without any drawback in terms of the final performances.The light RTM techniques was developed on purpose for the manufacturing of the curved pipe. The comparison between hand lay up and light RTM evidenced a substantial cost reduction when light RTM was used.

  8. Chemical Principles Revisited: The Chemistry of Glass.

    ERIC Educational Resources Information Center

    Kolb, Doris; Kolb, Kenneth E.

    1979-01-01

    Presents a detailed discussion on the chemistry of glass. Topics discussed include: natural glass, early history, modern glass composition, raw materials for glass melting, chemically modified glasses, modern glass forming, glass ceramics, and new developments in glass research. (BT)

  9. Inverse-Leidenfrost phenomenon on nanofiber mats on hot surfaces

    NASA Astrophysics Data System (ADS)

    Weickgenannt, Christina M.; Zhang, Yiyun; Sinha-Ray, Suman; Roisman, Ilia V.; Gambaryan-Roisman, Tatiana; Tropea, Cameron; Yarin, Alexander L.

    2011-09-01

    The Leidenfrost effect is a technically and industrially important phenomenon that severely restricts heat removal from high-heat-flux surfaces. A simple remedy to the Leidenfrost effect is provided by polymer nanofiber mats created and deposited by electrospinning on stainless steel surfaces. The influence of nanofiber mats on hydrodynamics and cooling efficiency of single drop impact onto hot surfaces has been investigated experimentally. The evolution of the drops has been recorded by a high-speed complimentary metal-oxide semiconductor camera, whereas the cooling temperature was measured by a thermocouple. A remarkable phenomenon was discovered: a mat of polymer nanofibers electrospun onto a heater surface can completely suppress the Leidenfrost effect, thereby increasing the rate of heat removal from the surface to the liquid drops significantly. The “inverse-Leidenfrost” effect is described qualitatively and quantitatively, providing clear physical reasons for the observed behavior.

  10. Pressure Mapping Mat for Tele-Home Care Applications

    PubMed Central

    Saenz-Cogollo, Jose Francisco; Pau, Massimiliano; Fraboni, Beatrice; Bonfiglio, Annalisa

    2016-01-01

    In this paper we present the development of a mat-like pressure mapping system based on a single layer textile sensor and intended to be used in home environments for monitoring the physical condition of persons with limited mobility. The sensor is fabricated by embroidering silver-coated yarns on a light cotton fabric and creating pressure-sensitive resistive elements by stamping the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) at the crossing points of conductive stitches. A battery-operated mat prototype was developed and includes the scanning circuitry and a wireless communication module. A functional description of the system is presented together with a preliminary experimental evaluation of the mat prototype in the extraction of plantar pressure parameters. PMID:26978369

  11. The MATS Satellite Mission - Tomographic Perspectives on the Mesosphere

    NASA Astrophysics Data System (ADS)

    Karlsson, B.; Gumbel, J.

    2015-12-01

    Tomography in combination with space-borne limb imaging opens exciting new ways of probing atmospheric structures. MATS (Mesospheric Airglow/Aerosol Tomography and Spectroscopy) is a new Swedish satellite mission that applies these ideas to the mesosphere. MATS science questions focus on mesospheric wave activity and noctilucent clouds. Primary measurement targets are O2 Atmospheric band dayglow and nightglow in the near infrared (759-767 nm) and sunlight scattered from noctilucent clouds in the ultraviolet (270-300 nm). While tomography provides horizontally and vertically resolved data, spectroscopy allows analysis in terms of mesospheric composition, temperature and cloud properties. This poster introduces instrument and analysis ideas, and discusses scientific perspectives and connections to other missions. MATS is being prepared for a launch in 2018.

  12. Low temperature selective absorber research

    NASA Astrophysics Data System (ADS)

    Herzenberg, S. A.; Silberglitt, R.

    1982-04-01

    Research carried out since 1979 on selective absorbers is surveyed, with particular attention given to the low-temperature coatings seen as promising for flat plate and evacuated tube applications. The most thoroughly investigated absorber is black chrome, which is highly selective and is the most durable low-temperature absorber. It is believed that other materials, because of their low cost and lower content of strategic materials, may eventually supplant black chrome. Among these candidates are chemically converted black nickel; anodically oxidized nickel, zinc, and copper composites; and nickel or other low-cost multilayer coatings. In reviewing medium and high-temperature research, black chrome, multilayer coatings and black cobalt are seen as best medium-temperature candidates. For high temperatures, an Al2O3/Pt-Al203 multilayer composite or the zirconium diboride coating is preferred.

  13. Microsensor measurements of hydrogen gas dynamics in cyanobacterial microbial mats.

    PubMed

    Nielsen, Michael; Revsbech, Niels P; Kühl, Michael

    2015-01-01

    We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria sp.). The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5-5 pA per μmol L(-1) H2). Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8-10% H2 saturation) within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1-2 h in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct biophotolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g., sulfate reduction or anoxygenic photosynthesis in microbial mats.

  14. Microsensor measurements of hydrogen gas dynamics in cyanobacterial microbial mats

    PubMed Central

    Nielsen, Michael; Revsbech, Niels P.; Kühl, Michael

    2015-01-01

    We used a novel amperometric microsensor for measuring hydrogen gas production and consumption at high spatio-temporal resolution in cyanobacterial biofilms and mats dominated by non-heterocystous filamentous cyanobacteria (Microcoleus chtonoplastes and Oscillatoria sp.). The new microsensor is based on the use of an organic electrolyte and a stable internal reference system and can be equipped with a chemical sulfide trap in the measuring tip; it exhibits very stable and sulfide-insensitive measuring signals and a high sensitivity (1.5–5 pA per μmol L-1 H2). Hydrogen gas measurements were done in combination with microsensor measurements of scalar irradiance, O2, pH, and H2S and showed a pronounced H2 accumulation (of up to 8–10% H2 saturation) within the upper mm of cyanobacterial mats after onset of darkness and O2 depletion. The peak concentration of H2 increased with the irradiance level prior to darkening. After an initial build-up over the first 1–2 h in darkness, H2 was depleted over several hours due to efflux to the overlaying water, and due to biogeochemical processes in the uppermost oxic layers and the anoxic layers of the mats. Depletion could be prevented by addition of molybdate pointing to sulfate reduction as a major sink for H2. Immediately after onset of illumination, a short burst of presumably photo-produced H2 due to direct biophotolysis was observed in the illuminated but anoxic mat layers. As soon as O2 from photosynthesis started to accumulate, the H2 was consumed rapidly and production ceased. Our data give detailed insights into the microscale distribution and dynamics of H2 in cyanobacterial biofilms and mats, and further support that cyanobacterial H2 production can play a significant role in fueling anaerobic processes like e.g., sulfate reduction or anoxygenic photosynthesis in microbial mats. PMID:26257714

  15. Fungal communities of young and mature hypersaline microbial mats.

    PubMed

    Cantrell, Sharon A; Tkavc, Rok; Gunde-Cimerman, Nina; Zalar, Polona; Acevedo, Manuel; Báez-Félix, Claribel

    2013-01-01

    Microbial mats are a laminated organic-sedimentary ecosystem, found in a wide range of habitats. Fluctuating diel and seasonal physicochemical gradients characterize these ecosystems, resulting in both strata and microenvironments that harbor specific microbial communities. This study was undertaken to compare two types of microbial mats across seasons to further understand the structure of fungal communities in hypersaline microbial mats and their seasonal dynamics. The structure and diversity of fungal communities was documented in young transient and mature hypersaline microbial mats from a tropical region (Puerto Rico) using one culture-dependent and three culture-independent molecular techniques based on the internal transcribed spacer (ITS) region of ribosomal DNA: terminal restriction fragment length polymorphism (TRFLP), denaturing gradient gel electrophoresis (DGGE) and clone libraries. Two microbial mats (one young and transient, one mature) were sampled in Nov 2007 (wet season), Jan 2008 (intermediate season) and Mar 2008 (dry season) in the Cabo Rojo Solar Salterns on the southwestern coast of Puerto Rico. Traditional and molecular techniques revealed strong spatial and temporal heterogeneities in both microbial mats. Higher abundance of isolates and phylotypes were observed during the wet season, and diversity decreased from the top (oxic) to the bottom (anoxic) layers in both seasons. Some of the species isolated belong to the genera Aspergillus, Cladosporium, Hortaea, Pichia and Wallemia, which often are isolated from hypersaline environments. The most abundant clones belong to Acremonium strictum and Cladosporium halotolerans, which were not isolated in pure culture. The differences observed using culture-based and molecular techniques demonstrates the need of combining methods to study the diversity of fungi in a given substrate.

  16. The Extracellular Matrix in Photosynthetic Mats: A Cyanobacterial Gingerbread House

    NASA Astrophysics Data System (ADS)

    Stuart, R.; Stannard, W.; Bebout, B.; Pett-Ridge, J.; Mayali, X.; Weber, P. K.; Lipton, M. S.; Lee, J.; Everroad, R. C.; Thelen, M.

    2014-12-01

    Hypersaline laminated cyanobacterial mats are excellent model systems for investigating photoautotrophic contributions to biogeochemical cycling on a millimeter scale. These self-sustaining ecosystems are characterized by steep physiochemical gradients that fluctuate dramatically on hour timescales, providing a dynamic environment to study microbial response. However, elucidating the distribution of energy from light absorption into biomass requires a complete understanding of the various constituents of the mat. Extracellular polymeric substances (EPS), which can be composed of proteins, polysaccharides, lipids and DNA are a major component of these mats and may function in the redistribution of nutrients and metabolites within the community. To test this notion, we established a model mat-building culture for comparison with the phylogenetically diverse natural mat communities. In these two systems we determined how proteins and glycans in the matrix changed as a function of light and tracked nutrient flow from the matrix. Using mass spectrometry metaproteomics analysis, we found homologous proteins in both field and culture extracellular matrix that point to cyanobacterial turnover of amino acids, inorganic nutrients, carbohydrates and nucleic acids from the EPS. Other abundant functions identified included oxidative stress response from both the cyanobacteria and heterotrophs and cyanobacterial structural proteins that may play a role in mat cohesion. Several degradative enzymes also varied in abundance in the EPS in response to light availability, suggesting active secretion. To further test cyanobacterial EPS turnover, we generated isotopically-labeled EPS and used NanoSIMS to trace uptake of this labeled EPS. Our findings suggest Cyanobacteria may facilitate nutrient transfer to other groups, as well as uptake of their own products through degradation of EPS components. This work provides evidence for the essential roles of EPS for storage, structural

  17. Magnetically tunable metamaterial perfect absorber

    NASA Astrophysics Data System (ADS)

    Lei, Ming; Feng, Ningyue; Wang, Qingmin; Hao, Yanan; Huang, Shanguo; Bi, Ke

    2016-06-01

    A magnetically tunable metamaterial perfect absorber (MPA) based on ferromagnetic resonance is experimentally and numerically demonstrated. The ferrite-based MPA is composed of an array of ferrite rods and a metallic ground plane. Frequency dependent absorption of the ferrite-based MPA under a series of applied magnetic fields is discussed. An absorption peak induced by ferromagnetic resonance appears in the range of 8-12 GHz under a certain magnetic field. Both the simulated and experimental results demonstrate that the absorption frequency of the ferrite-based MPA can be tuned by the applied magnetic field. This work provides an effective way to fabricate the magnetically tunable metamaterial perfect absorber.

  18. Adaptive inertial shock-absorber

    NASA Astrophysics Data System (ADS)

    Faraj, Rami; Holnicki-Szulc, Jan; Knap, Lech; Seńko, Jarosław

    2016-03-01

    This paper introduces and discusses a new concept of impact absorption by means of impact energy management and storage in dedicated rotating inertial discs. The effectiveness of the concept is demonstrated in a selected case-study involving spinning management, a recently developed novel impact-absorber. A specific control technique performed on this device is demonstrated to be the main source of significant improvement in the overall efficiency of impact damping process. The influence of various parameters on the performance of the shock-absorber is investigated. Design and manufacturing challenges and directions of further research are formulated.

  19. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  20. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  1. Antimony sulphide, an absorber layer for solar cell application

    NASA Astrophysics Data System (ADS)

    Ali, N.; Hussain, Arshad; Ahmed, R.; Shamsuri, W. N. Wan; Shaari, A.; Ahmad, N.; Abbas, S. M.

    2016-01-01

    Replacement of the toxic, expensive and scarce materials with nontoxic, cheap and earth-abundant one, in solar cell absorber layer, is immensely needed to realize the vision of green and sustainable energy. Two-micrometre-thin antimony sulphide film is considered to be adequate as an absorbing layer in solar cell applications. In this paper, we synthesize antimony sulphide thin films on glass substrate by physical vapour deposition technique, and the obtained films were then annealed at different temperatures (150-250 °C). The as-deposited and annealed samples were investigated for structural and optoelectronic properties using different characterization techniques. The X-ray diffraction analysis showed that the annealed samples were polycrystalline with Sb2S3 phase, while the as-deposited sample was amorphous in nature. The optical properties are measured via optical ellipsometric techniques. The measured absorbance of the film is adequately high, and every photon is found to be absorbed in visible and NIR range. The conductivity type of the films measured by hot-point probe technique is determined to be p-type. The optical band gap of the resulted samples was in the range (2.4-1.3 eV) for the as-deposited and annealed films.

  2. Evaluation of Parameters Affecting Horizontal Stability of Landing Mats

    DTIC Science & Technology

    1976-09-01

    1974. A rmathematical 11aodel tio silluatet the buckling response oif thte tria’i to th;: hora /ttntal ltAds way, atso elp. 1 h reuls o th...NO. 19R-20-0 MAT XU19, 4-FT X 4*PT ZERO ECCENTRICITY WIT420T EJGH48F NOTE NUMBERS SL LINES .RE HORIZONTAL FORC~E (LEFT) AND HORIZONTAL MOVEMENT ,RIGH...connector bars 14- TEST NO. 19-20-0 MAT XM19, 4-FT X 4-FT WIDTH 20-FT, LENGTH 48-FT ZERO ECCENTRICITY S-NG NUMBERS BYLINES ARE HORIZONTAL FORCE (LEFT) AND

  3. Inverted glass harp

    NASA Astrophysics Data System (ADS)

    Quinn, Daniel B.; Rosenberg, Brian J.

    2015-08-01

    We present an analytical treatment of the acoustics of liquid-filled wine glasses, or "glass harps." The solution is generalized such that under certain assumptions it reduces to previous glass harp models, but also leads to a proposed musical instrument, the "inverted glass harp," in which an empty glass is submerged in a liquid-filled basin. The versatility of the solution demonstrates that all glass harps are governed by a family of solutions to Laplace's equation around a vibrating disk. Tonal analyses of recordings for a sample glass are offered as confirmation of the scaling predictions.

  4. Glass-silicon column

    DOEpatents

    Yu, Conrad M.

    2003-12-30

    A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

  5. The heterothallic sugarbeet pathogen Cercospora beticola contains exon fragments of both MAT genes that are homogenized by concerted evolution

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dothideomycetes is one of the most ecologically diverse and economically important classes of fungi. Sexual reproduction in this group is governed by mating type (MAT) genes at the MAT1 locus. Self-sterile (heterothallic) species contain one of two genes at MAT1, MAT1-1-1 or MAT1-2-1, and only isol...

  6. Optimization of the contents of hollow glass microsphere and sodium hexametaphosphate for glass fiber vacuum insulation panel

    NASA Astrophysics Data System (ADS)

    Li, C. D.; Chen, Z. F.; Zhou, J. M.

    2016-07-01

    In this paper, various additive amounts of hollow glass microspheres (HGMs) and sodium hexametaphosphate (SHMP) powders were blended with flame attenuated glass wool (FAGW) to form hybrid core materials (HCMs) through the wet method. Among them, the SHMP was dissolved in the glass fiber suspension and coated on the surface of glass fibers while the HGMs were insoluble in the glass fiber suspension and filled in the fiber-fiber pores. The average pore diameter of the FAGW/HGM HCMs was 8-11 μm which was near the same as that of flame attenuated glass fiber mats (FAGMs, i.e., 10.5 µm). The tensile strength of the SHMP coated FAGMs was enhanced from 160 N/m to 370 N/m when SHMP content increased from 0 wt.% to 0.2 wt.%. By contrast, the tensile strength of the FAGW/HGM HCMs decreased from 160 N/m to 40 N/m when HGM content increased from 0 wt.% to 50 wt.%. Both the FAGW/HGM HCMs and SHMP coated FAGMs were vacuumed completely to form vacuum insulation panels (VIPs). The results showed that both the addition of SHMP and HGM led a slight increase in the thermal conductivity of the corresponding VIPs. To obtain a high-quality VIP, the optimal SHMP content and HGM content in glass fiber suspension was 0.12-0.2 wt.% and 0 wt.%.

  7. Counterflow absorber for an absorption refrigeration system

    DOEpatents

    Reimann, Robert C.

    1984-01-01

    An air-cooled, vertical tube absorber for an absorption refrigeration system is disclosed. Strong absorbent solution is supplied to the top of the absorber and refrigerant vapor is supplied to the bottom of the absorber to create a direct counterflow of refrigerant vapor and absorbent solution in the absorber. The refrigeration system is designed so that the volume flow rate of refrigerant vapor in the tubes of the absorber is sufficient to create a substantially direct counterflow along the entire length of each tube in the absorber. This provides several advantages for the absorber such as higher efficiency and improved heat transfer characteristics, and allows improved purging of non-condensibles from the absorber.

  8. Metamaterial Absorbers for Microwave Detection

    DTIC Science & Technology

    2015-06-01

    a) Depiction of metamaterial array of square resonators atop FR4. (b) Metamaterial dimensions and structure...comparison for varying resonator array dimension sizes. ..............23 Figure 12. Absorption derived from raw reflection data...36 x Figure 23. Metamaterial absorber array where resonator dimensions control the detection frequencies and

  9. Oil and fat absorbing polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr. (Inventor)

    1977-01-01

    A method is described for forming a solid network polymer having a minimal amount of crosslinking for use in absorbing fats and oils. The polymer remains solid at a swelling ratio in oil or fat of at least ten and provides an oil absorption greater than 900 weight percent.

  10. Growth of a mat-forming photograph in the presence of UV radiation

    NASA Technical Reports Server (NTRS)

    Pierson, Beverly K.; Ruff, A. L.

    1989-01-01

    Knowledge of the survival and growth of microorganisms in the presence of ultraviolet radiation is important for understanding the potential for life to exist in environments exposed to high fluxes of UV radiation. The growth of a mat-forming phototrophic prokaryote, Chloroflexus aurantiacus, was examined in the presence of continuous high UV irradiation under otherwise optimal growth conditions. Evidence was sought for an intrinsic ability to grow in the presence of UV radiation in a carefully chosen organism known to be unusually resistant to UV radiation, of ancient lineage among the phototrophs, to resemble ancient microfossils from the Precambrian, and to be a mat-former. It was assumed that even a high intrinsic UV resistance would be inadequate for survival and growth in the presence of very high UV fluxes, and iron (Fe3+) was selected as a common, abundant UV-absorbing substance that might protest microorganisms growing in or under iron-bearing sediments. The effectiveness of Fe(3+) was tested as a UV protective agent at low concentrations in thin layers. It was concluded that intrinsic UV resistance in some organisms may account for growth, not just survival, of these organisms when exposed to high UV fluxes under otherwise optimal growth conditions in an anoxic environment. It was also concluded that Fe(3+) bearing sediments of 1 mm or less in thickness may provide an adequate shield against high UV fluxes permitting the growth of microorganisms just below their surface. As long as growth conditions were met, then the evolution and development of microorganisms would not be hampered by high UV fluxes impinging upon the surface of iron-bearing sediments.

  11. Altering sexual reproductive mode by interspecific exchange of MAT loci

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sexual fungi can be self-sterile (heterothallic, requiring genetically distinct partners) or selffertile (homothallic, no partner required). In most ascomycetes, a single mating type locus (MAT) controls the ability to reproduce sexually. In the genus Cochliobolus, all heterothallic species have eit...

  12. Performance of ballast mats on passenger railroads: Measurement vs. projections

    NASA Astrophysics Data System (ADS)

    Hanson, C. E.; Singleton, H. L.

    2006-06-01

    Ballast mats have been installed on urban railway systems throughout the world to provide isolation of ground-borne vibrations from trains. In general, the performance has been found to be satisfactory. However, often there is a variance between the claims of the suppliers of ballast mats and the actual performance of the product in the real world. The classic case involves an infinite terminal impedance applicable to a tunnel configuration. However, a ballast mat installation outdoors on surface track with sub-grade slabs may not have the same performance as a tunnel base where sides are stiffened by walls. In order to represent this situation, Kimura developed a simplified prediction procedure based on an original Wettschureck/Kurze model, with a finite termination impedance based on a flat beam model. This prediction procedure has been tested against measurements on at-grade installations on light rail transit and commuter railway installations in Baltimore and Boston. In both cases, the model showed good agreement with measured values for the resonant frequency dip and the mid-frequency insertion loss. At higher frequencies, however, the model over-predicted the insertion loss, as do many of the models used by ballast mat suppliers. Suggestions are made to account for the discrepancies between predicted and measured values.

  13. Microbial mats and the search for minimal ecosystems.

    PubMed

    Guerrero, R; Piqueras, M; Berlanga, M

    2002-12-01

    This article reviews some ecological concepts common to all kinds of ecosystems, describes the characteristics of microbial mats, and focuses on the description of the Ebro Delta microbial mats, to assess whether they fit the concept of a minimal ecosystem. First, microorganisms as components of ecosystems are considered, and some features of microbial life, including ubiquity, size and metabolism, genetic versatility, and strategies to overcome unfavorable conditions, are discussed. Models for ecosystems, regardless of their size, have the same basic components; tropical forests, multilayered planktonic microbial communities, and benthic microbial mats are analogous ecosystems at different scales. The structure--in terms of populations and communities--and ecophysiology of microbial mats are also discussed. The linear distribution of microbial populations along steep gradients of light and hydrogen sulfide allows for the simultaneous presence of different microbial populations. Defining the minimal ecosystem requirements necessary for the survival and proliferation of organisms is crucial in the search for extraterrestrial life and for establishing ecosystems beyond the Earth.

  14. Detail of the underground wire net mat and cable at ...

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

    Detail of the underground wire net mat and cable at the base of a 94' low-band reflector screen pole, view facing north - U.S. Naval Base, Pearl Harbor, Naval Radio Station, AF/FRD-10 Circularly Disposed Antenna Array, Wahiawa, Honolulu County, HI

  15. Electrospinning of caseinates to create protective fibrous mats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Electrospinning is a nonthermal process that produces fibers on the micron- or nano-scale from a polymer solution. If produced by electrospinning of biopolymer solutions, fibrous mats may be created for protecting foods and allowing for the preservation and controlled release of bioactives for healt...

  16. Electrospinning of caseinates to create protective fibrous mats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    JUSTIFICATION Electrospinning is a nonthermal process that produces fibers with diameters on the micron- or nano-scales from a polymer solution. If produced by electrospinning of biopolymer solutions, fibrous mats may be created for protecting foods, improving food quality and allowing for the prese...

  17. Compositions and methods of use of constructed microbial mats

    DOEpatents

    Bender, Judith A.; Phillips, Peter C.

    2000-01-01

    Compositions, methods and devices for bioremediation that comprise components of constructed microbial mats with organic and inorganic materials are described. The compositions, methods and devices can be used for bioremediation of different individual contaminants and for mixed or multiple contaminants, and for production of beneficial compositions and molecules.

  18. Direct piezoelectric responses of soft composite fiber mats

    NASA Astrophysics Data System (ADS)

    Varga, M.; Morvan, J.; Diorio, N.; Buyuktanir, E.; Harden, J.; West, J. L.; Jákli, A.

    2013-04-01

    Recently soft fiber mats electrospun from solutions of Barium Titanate (BT) ferroelectric ceramics particles and polylactic acid (PLA) were found to have large (d33 ˜ 1 nm/V) converse piezoelectric signals offering a myriad of applications ranging from active implants to smart textiles. Here, we report direct piezoelectric measurements (electric signals due to mechanical stress) of the BT/PLA composite fiber mats at several BT concentrations. A homemade testing apparatus provided AC stresses in the 50 Hz-1.5 kHz-frequency range. The piezoelectric constant d33 ˜ 0.5 nC/N and the compression modulus Y ˜ 104-105 Pa found are in agreement with the prior converse piezoelectric and compressibility measurements. Importantly, the direct piezoelectric signal is large enough to power a small LCD by simple finger tapping of a 0.15 mm thick 2-cm2 area mat. We propose using these mats in active Braille cells and in liquid crystal writing tablets.

  19. Method and system of culturing an algal mat

    DOEpatents

    Das, Keshav C; Cannon, Benjamin R; Bhatnagar, Ashish; Chinnasamy, Senthil

    2014-05-13

    A system and method for culturing algae are presented. The system and method utilize a fog of growth medium that is delivered to an algal mat generator along with a stream of CO.sub.2 to promote growth of algal cells contained in the generator.

  20. Myocardial Cell Pattern on Piezoelectric Nanofiber Mats for Energy Harvesting

    NASA Astrophysics Data System (ADS)

    Liu, X.; Wang, X.; Zhao, H.; Du, Y.

    2014-11-01

    The paper presents in vitro contractile myocardial cell pattern on piezoelectric nanofiber mats with applications in energy harvesting. The cell-based energy harvester consists of myocardial cell sheet and a PDMS substrate with a PVDF nanofiber mat on. Experimentally, cultured on specifically distributed nanofiber mats, neonatal rat ventricular cardiomyocytes are characterized with the related morphology and contraction. Previously, we have come up with the concept of energy harvesting from heart beating using piezoelectric material. A bio-hybrid energy harvester combined living cardiomyocytes, PDMS polymer substrate and piezoelectric PVDF film with the electrical output of peak current 87.5nA and peak voltage 92.3mV. However, the thickness of the cardiomyocyte cultured on a two-dimensional substrate is much less than that of the piezoelectric film. The Micro Contact Printing (μCP) method used in cell pattern on the PDMS thin film has tough requirement for the film surface. As such, in this paper we fabricated nanofiber-constructed PDMS thin film to realize cell pattern due to PVDF nanofibers with better piezoelectricity and microstructures of nanofiber mats guiding cell distribution. Living cardiomyocytes patterned on those distributed piezoelectric nanofibers with the result of the same distribution as the nanofiber pattern.

  1. HiMAT highly maneuverable aircraft technology, flight report

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Flight verification of a primary flight control system, designed to control the unstable HiMAT aircraft is presented. The initial flight demonstration of a maneuver autopilot in the level cruise mode and the gathering of a limited amount of airspeed calibration data.

  2. Bioremediation of hexavalent chromium by a cyanobacterial mat

    NASA Astrophysics Data System (ADS)

    Shukla, Dhara; Vankar, Padma S.; Srivastava, Sarvesh Kumar

    2012-12-01

    The study comprises the use of cyanobacterial mat (collected from tannery effluent site) to remove hexavalent chromium. This mat was consortium of cyanobacteria/blue-green algae such as Chlorella sp., Phormidium sp. and Oscillatoria sp. The adsorption experiments were carried out in batches using chromium concentrations 2-10, 15-30 and 300 ppm at pH 5.5-6.2. The adsorption started within 15 min; however, 96 % reduction in metal concentration was observed within 210 min. The adsorption phenomenon was confirmed by Fourier transform-infrared spectroscopy and energy dispersive X-ray analysis. This biosorption fitted Freundlich adsorption isotherm very well. It was observed that the best adsorption was at 4 ppm, and at 25 ppm in the chosen concentration ranges. Scanning electron micrograph showed the physiology of mat, indicating sites for metal uptake. The main focus was collection of the cyanobacterial mat from local environments and its chromium removal potential at pH 5.5-6.2.

  3. Mechanical behavior, modeling, and color change of electrospun fiber mats

    NASA Astrophysics Data System (ADS)

    Pedicini, Angelo

    The process of electrospinning and the physical properties of electrospun fibers are presented in this thesis. In electrospinning, polymeric fibers having diameters ranging from 50 nanometers to 1 micrometer are prepared by applying high static charge to a polymer solution. The mechanical properties and molecular morphology of some electrospun polymers are shown to be fundamentally different compared to their bulk analogs. Experimental results indicate that the mechanical behavior of electrospun polyurethane fiber mats is influenced by fiber mat morphology, molecular orientation, and surface flaws on electrospun fibers. This research characterizes the mechanical behavior of randomly oriented electrospun polyurethane mats and sheds light on general differences in behavior between electrospun and bulk materials. Further, the mechanical response of random fiber mats is modeled based on the mechanical characterization of aligned electrospun fibers. Also, empirical models are employed to relate the tensile properties of electrospun materials to their bulk analogs. The crystallinity and melting behavior of a family of electrospun polyesters is studied and provides insight to the rapid cooling and effects on solidification and crystallization of electrospun polymeric fibers. The results indicate a commonly accepted idea in electrospinning, that electrospun fibers result from rapid solvent evaporation and experience quench-like solidification from a jet of polymer solution. A qualitative study illustrates a color change phenomenon in a series of electrospun polymer/solvent systems. Color change is produced by electrospinning, and subsequent heating, and occurs at characteristic temperatures dependent on the polymer system used. These color change systems are also demonstrated as candidates for imageable media.

  4. Picture Wall (Glass Structures)

    NASA Technical Reports Server (NTRS)

    1978-01-01

    Photo shows a subway station in Toronto, Ontario, which is entirely glass-enclosed. The all-glass structure was made possible by a unique glazing concept developed by PPG Industries, Pittsburgh, Pennsylvania, one of the largest U.S. manufacturers of flat glass. In the TVS glazing system, transparent glass "fins" replace conventional vertical support members used to provide support for wind load resistance. For stiffening, silicone sealant bonds the fins to adjacent glass panels. At its glass research center near Pittsburgh, PPG Industries uses the NASTRAN computer program to analyze the stability of enclosures made entirely of glass. The company also uses NASTRAN to simulate stresses on large containers of molten glass and to analyze stress effects of solar heating on flat glass.

  5. OVI absorbers in SDSS spectra

    NASA Astrophysics Data System (ADS)

    Frank, Stephan

    We conducted a systematic search for signatures of the Intergalactic Medium (IGM) in Quasar spectra of the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3), focusing on finding intervening absorbers via detection of their O VI doublet. We present a search algorithm, and criteria for distinguishing candidates from spurious Lyman a forest lines. In addition, we compare our findings with simulations of the Lyman a forest in order to estimate the detectability of O VI doublets over various redshift intervals. We obtain a sample of 1866 O VI doublet candidates with rest-frame equivalent width >= 0.05 λ in 855 AGN spectra (out of 3702 objects with redshifts in the range accessible for O VI detection). This sample is subdivided into 3 groups according to the likelihood of being real and the potential for follow-up observation of the candidate. The group with the cleanest and most secure candidates is comprised of 145 candidates. 69 of these reside at a velocity separation >= 5000 km/s from the QSO, and can therefore be classified tentatively as intervening absorbers. Most of these absorbers have not been picked up by earlier, automated QSO absorption line detection algorithms. This sample increases the number of known O VI absorbers at redshifts beyond z abs >= 2.7 substantially. We propose to obtain observations of some of the candidates with the best signatures for O VI doublets with high signal-to-noise and high resolution in order to better constrain the physical state of the absorbers. We then focused on a subsample of 387 AGN sightlines with an average S/N >= 5: 0, allowing for the detection of absorbers above a rest-frame equivalent width limit of W r >= 0:19 ? A for the O VI 1032 λ component. Accounting for random interlopers mimicking an O VI doublet, we derive for the first time a secure lower limit for the redshift number density DN/Dz for redshifts z abs >= 2:8. With extensive Monte Carlo simulations we quantify the losses of absorbers due to blending

  6. Bioactive glasses and glass-ceramics.

    PubMed

    Rawlings, R D

    1993-01-01

    Bioactive materials are designed to induce a specific biological activity; in most cases the desired biological activity is one that will give strong bonding to bone. A range of materials has been assessed as being capable of bonding to bone, but this paper is solely concerned with bioactive glasses and glass-ceramics. Firstly, the structure and processing of glasses and glass-ceramics are described, as a basic knowledge is essential for the understanding of the development and properties of the bioactive materials. The effect of composition and structure on the bioactivity is then discussed, and it will be shown that bioactivity is associated with the formation of an apatite layer on the surface of the implant. A survey of mechanical performance demonstrates that the structure and mechanical properties of glass-ceramics depend upon whether the processing involves casting or sintering and that the strength and toughness of glass-ceramics are superior to those of glasses. Attempts to further improve the mechanical performance by the use of non-monolithic components, i.e. bioactive coatings on metal substrates and glass and glass-ceramic matrix composites, are also reviewed and are shown to have varying degrees of success. Finally, some miscellaneous applications, namely bioactive bone cements and bone fillers, are briefly covered.

  7. Reaction cured glass and glass coatings

    NASA Technical Reports Server (NTRS)

    Goldstein, H. E.; Leiser, D. B.; Katvala, V. W. (Inventor)

    1978-01-01

    The invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482C (2700PF).

  8. Carbon nanotube mat as mediator-less glucose sensor electrode.

    PubMed

    Ryu, Jongeun; Kim, Hansang; Lee, Sangeui; Hahn, H Thomas; Lashmore, David

    2010-02-01

    In this paper, the direct electron transfer of glucose oxidase (GOx) on carbon nanotube (CNT) mat electrode is demonstrated. Because of the electrical conductivity and mechanical strength of CNT mat, it can be used as an electrode as well as a catalyst support. Therefore, the preparation process for the CNT mat based sensor electrode is simpler than that of the conventional CNT dispersed sensor electrodes. GOx was covalently immobilized on the oxidized CNT mat, which is connected to a wire by using silver paste and epoxy glue. Attenuated Total Reflectance Fourier Transform-Infrared (ATR-FTIR) result shows transmittance peaks at 1637 cm(-1) and 1525 cm(-1) which are corresponding to the band I and II of amide. Cyclic voltammetric shows a pair of well-defined redox peaks with the average formal potential of -0.425 V (vs. Ag/AgCl reference electrode) in the phosphate buffered saline solution (1 x PBS, pH 7.4). Calculated electron transfer rate constant and the surface density of GOx were 1.71 s(-1) and (3.27 +/- 0.20) x 10(-13) mol/cm2, respectively. Cyclic voltammograms of GOx-CNT mat in glucose solution show that the immobilized GOx retains its catalytic activity to glucose. The amperometric sensor response showed a linear dependence on the glucose concentration in the range of 0.2 mM to 2.18 mM with a detection sensitivity of 4.05 microA mM(-1) cm(-2). The Michaelis-Menten constant of the immobilized GOx was calculated to be 2.18 mM.

  9. Hyperpolarized cesium ions doped in a glass material.

    PubMed

    Ishikawa, Kiyoshi

    2014-10-17

    Hyperpolarized (HP) (133)Cs nuclear magnetic resonance signals were measured from borosilicate glass cell walls during optical pumping of cesium vapor at high magnetic field (9.4T). Significant signal enhancements were observed when additional heating of the cell wall was provided by intense but non-resonant laser irradiation, with integrated HP (133)Cs NMR signals and line widths varying as a function of heating laser power (and hence glass temperature). Given that virtually no Cs ions would originally be present in the glass, absorbed HP Cs atoms rarely met thermally-polarized Cs ions already at the surface; thus, spin-exchange via nuclear dipole interaction cannot be the primary mechanism for injecting spin polarization into the glass. Instead, it is concluded that the absorption and transport of HP atoms into the glass material itself is the dominant mechanism of nuclear spin injection at high temperatures-the first reported experimental demonstration of such a mechanism.

  10. Local protective effects of oral 45S5 bioactive glass on gastric ulcers in experimental animals.

    PubMed

    Ma, Ai-niu; Gong, Nian; Lu, Jin-miao; Huang, Jin-lu; Hao, Bin; Guo, Yang; Zhong, Jipin; Xu, Yuhong; Chang, Jiang; Wang, Yong-xiang

    2013-03-01

    Bioactive glass has been shown to stimulate bone regeneration and soft tissue healing. In this study, we evaluated the local protective effects of bioactive glass on experimental gastric ulcers, in comparison with omeprazole and hydrotalcite. Single and multiple gavage of 45S5 bioactive glass dose-dependently protected stress ulcers in mice and chronic ulcers in rats. Multi-daily gavage of bioactive glass for 7 days prevented chronic ulcer recurrence by 50 %. Bioactive glass ionic dissolution produced marked proliferation of ethanol-injured GES-1 human gastric mucosa epithelial cells 48 and 72 h after exposure. Bioactive glass was shown to be hardly absorbed after single or multi-daily gavage. This study, for the first time, demonstrates that bioactive glass is effective in protecting against gastric ulcers, with its high efficacy comparable to omeprazole and superior to hydrotalcite. The lack of oral absorption makes bioactive glass a potential for treatment of peptic ulcers omitting systemic toxicity or side-effects.

  11. Digital Alloy Absorber for Photodetectors

    NASA Technical Reports Server (NTRS)

    Hill, Cory J. (Inventor); Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor)

    2016-01-01

    In order to increase the spectral response range and improve the mobility of the photo-generated carriers (e.g. in an nBn photodetector), a digital alloy absorber may be employed by embedding one (or fraction thereof) to several monolayers of a semiconductor material (insert layers) periodically into a different host semiconductor material of the absorber layer. The semiconductor material of the insert layer and the host semiconductor materials may have lattice constants that are substantially mismatched. For example, this may performed by periodically embedding monolayers of InSb into an InAsSb host as the absorption region to extend the cutoff wavelength of InAsSb photodetectors, such as InAsSb based nBn devices. The described technique allows for simultaneous control of alloy composition and net strain, which are both key parameters for the photodetector operation.

  12. 6. Looking glass aircraft in the project looking glass historic ...

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

    6. Looking glass aircraft in the project looking glass historic district. View to north. - Offutt Air Force Base, Looking Glass Airborne Command Post, Looking Glass Avenue between Comstat Drive & Nightwatch Avenue, Offutt Air Force Base, Bellevue, Sarpy County, NE

  13. Oxynitride glass fibers

    NASA Technical Reports Server (NTRS)

    Patel, Parimal J.; Messier, Donald R.; Rich, R. E.

    1991-01-01

    Research at the Army Materials Technology Laboratory (AMTL) and elsewhere has shown that many glass properties including elastic modulus, hardness, and corrosion resistance are improved markedly by the substitution of nitrogen for oxygen in the glass structure. Oxynitride glasses, therefore, offer exciting opportunities for making high modulus, high strength fibers. Processes for making oxynitride glasses and fibers of glass compositions similar to commercial oxide glasses, but with considerable enhanced properties, are discussed. We have made glasses with elastic moduli as high as 140 GPa and fibers with moduli of 120 GPa and tensile strengths up to 2900 MPa. AMTL holds a U.S. patent on oxynitride glass fibers, and this presentation discusses a unique process for drawing small diameter oxynitride glass fibers at high drawing rates. Fibers are drawn through a nozzle from molten glass in a molybdenum crucible at 1550 C. The crucible is situated in a furnace chamber in flowing nitrogen, and the fiber is wound in air outside of the chamber, making the process straightforward and commercially feasible. Strengths were considerably improved by improving glass quality to minimize internal defects. Though the fiber strengths were comparable with oxide fibers, work is currently in progress to further improve the elastic modulus and strength of fibers. The high elastic modulus of oxynitride glasses indicate their potential for making fibers with tensile strengths surpassing any oxide glass fibers, and we hope to realize that potential in the near future.

  14. Gelatin blending and sonication of chitosan nanofiber mats produce synergistic effects on hemostatic functions.

    PubMed

    Gu, Bon Kang; Park, Sang Jun; Kim, Min Sup; Lee, Yong Jin; Kim, Jong-Il; Kim, Chun-Ho

    2016-01-01

    To improve the hemostatic function of chitosan nanofiber mats, we studied the synergetic effects of gelatin blending and porosity control. Gelatin-blended-chitosan (Chi-Gel) nanofiber mats were evaluated with respect to surface morphology, mechanical properties and wettability, and functionally tested in a blood clotting study. The blood clotting efficiency of Chi-Gel nanofiber mats using rabbit whole blood in vitro was superior to that of chitosan nanofibers. Moreover, Chi-Gel nanofiber mats with enlarged porosity, produced by ultra-sonication, showed improved blood clotting efficiency, cell viability and cell infiltration compared with non-sonicated Chi-Gel nanofiber mats. Field-emission scanning electron microscopy revealed a richer density of platelets on sonicated nanofiber mats than on non-sonicated nanofiber mats after 3 min of blood clotting. The proliferation of human dermal fibroblast cells on sonicated Chi-Gel nanofiber mats using the DNA assay was higher than that on non-sonicated chitosan nanofiber mats after 7 days of culture. Confocal z-stack images showed that sonicated Chi-Gel nanofiber mats with high porosity supported active cell migration and infiltration into the 3-dimensional nanofiber mats. These results suggest that hydrophilic gelatin blending and sonication of chitosan nanofiber mats yields synergistic effects that not only improve hemostatic function but also promote wound repair.

  15. Users guide for ERB 7 MAT (including the first year quality control)

    NASA Technical Reports Server (NTRS)

    Groveman, B.

    1984-01-01

    In the first section of this report background information for the use of the ERB-7 Master Archival Tapes (MAT) is provided. The second section gives details regarding the scientific validity and quality of the MAT. The MAT data analyzed covers the period from November 16, 1978 to October 31, 1979.

  16. The Effects of Low Sulfate Concentrations on Modern Microbial Mat Communities: A Long Term Manipulation

    NASA Technical Reports Server (NTRS)

    Bebout, Brad; Carpenter, Steve; DesMarais, David J.; Discipulo, Mykell; Hogan, Mary; Turk, Kendra

    2002-01-01

    Microbial mats were widespread during the first ca. 2 Ga. of our biosphere's history. To better understand microbial ecosystems and their biomarkers under the low sulfate levels present in early oceans, we attempted a long-term (ca. 1 year) manipulation of sulfate in modem mats. Mats collected from salt ponds at Guerrero Negro, Baja Calif. Sur were incubated in a Greenhouse "Collaboratory" at Ames. Mats were maintained in artificial seawater brine containing either: 1) sulfate levels normal for these mats (70 mM), or 2) brine in which sulfate was replaced by chloride. Sulfate concentrations in the "low sulfate" brine gradually approached their lowest (to date) value of 0. 1 mM as sulfate was consumed and/or diffused out of the mat over a period of ca. 4 months. During that period of time, a number of differences between the treatments emerged. Relative to the "low sulfate" mats, "normal sulfate" mats had: 1) lower consumption of oxygen in the lower levels of the mat, 2) higher efficiencies of oxygenic photosynthesis, and 3) higher rates of nitrogen fixation. Rates of methane production by the mats increased greatly as sulfate concentrations fell below ca. 0.2 mM. In contrast, "low" and "normal" sulfate mats had similar net rates of exchange of O2 and dissolved inorganic C between the mats and overlying water. Reduced sulfate levels have diverse impacts upon these ecosystems.

  17. Energy-Absorbing, Lightweight Wheels

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Improved energy-absorbing wheels are under development for use on special-purpose vehicles that must traverse rough terrain under conditions (e.g., extreme cold) in which rubber pneumatic tires would fail. The designs of these wheels differ from those of prior non-pneumatic energy-absorbing wheels in ways that result in lighter weights and more effective reduction of stresses generated by ground/wheel contact forces. These wheels could be made of metals and/or composite materials to withstand the expected extreme operating conditions. As shown in the figure, a wheel according to this concept would include an isogrid tire connected to a hub via spring rods. The isogrid tire would be a stiff, lightweight structure typically made of aluminum. The isogrid aspect of the structure would both impart stiffness and act as a traction surface. The hub would be a thin-walled body of revolution having a simple or compound conical or other shape chosen for structural efficiency. The spring rods would absorb energy and partially isolate the hub and the supported vehicle from impact loads. The general spring-rod configuration shown in the figure was chosen because it would distribute contact and impact loads nearly evenly around the periphery of the hub, thereby helping to protect the hub against damage that would otherwise be caused by large loads concentrated onto small portions of the hub.

  18. Damage assessment and progression in a polyisocyanurate-based continuous swirl mat composite

    NASA Astrophysics Data System (ADS)

    Worley, Darwell Carlton, II

    This research conducted in conjunction with Oak Ridge National Laboratories and the Automotive Composite Consortium, ACC, was motivated by the desire to reduce vehicle weight for increased efficiency. At present, there are no databases of failure mechanisms, experimental procedures to study failure, mathematical expressions for empirical or theoretical prediction of properties of a continuous swirl mat composite, CSMC. Therefore, to contribute to the increased utilization of this class of materials the following research was performed. This research enabled the failure mechanism to be formulated, development of a method to quantify failure based on ultrasonic attenuation maps, and the prediction of the fracture toughness parameter KIC. The use of scanning electron microscopy, light microscopy, and real-time tensile loading showed that the CSMC failed in a brittle mode. These techniques also provided imaging information as to how a dominant crack propagates in the presence of a continuously swirled E-glass mat reinforcement and voids. This evaluation enabled a reconstruction of failure in order to demonstrate a possible failure mechanism. The aforementioned techniques revealed that the dominant crack follows the fiber/matrix interface, but may be influenced by the presence of voids. Voids have the tendency of luring the growing crack away from the interface. A growing crack would, however, return to a fiber/matrix interface until complete failure occurred. Another aspect of this work was the quantification of progressive damage using ultrasound. Comparisons were made between ultrasonic attenuation maps for unloaded and sequentially loaded specimens. The sequential loads were applied at different percentages of the ultimate tensile strength, UTS. This technique provided attenuation maps for a series of specimens with a controlled degree of damage, which showed an increase in attenuation with an increase in percent UTS. Fracture toughness experiments yielded an

  19. Regulation of electron transfer processes affects phototrophic mat structure and activity

    DOE PAGES

    Ha, Phuc T.; Renslow, Ryan S.; Atci, Erhan; ...

    2015-09-03

    Phototrophic microbial mats are among the most diverse ecosystems in nature. These systems undergo daily cycles in redox potential caused by variations in light energy input and metabolic interactions among the microbial species. In this work, solid electrodes with controlled potentials were placed under mats to study the electron transfer processes between the electrode and the microbial mat. The phototrophic microbial mat was harvested from Hot Lake, a hypersaline, epsomitic lake located near Oroville (Washington, USA). We operated two reactors: graphite electrodes were polarized at potentials of -700 mVAg/AgCl [cathodic (CAT) mat system] and +300 mVAg/AgCl [anodic (AN) mat system]more » and the electron transfer rates between the electrode and mat were monitored. We observed a diel cycle of electron transfer rates for both AN and CAT mat systems. Interestingly, the CAT mats generated the highest reducing current at the same time points that the AN mats showed the highest oxidizing current. To characterize the physicochemical factors influencing electron transfer processes, we measured depth profiles of dissolved oxygen (DO) and sulfide in the mats using microelectrodes. We further demonstrated that the mat-to-electrode and electrode-to-mat electron transfer rates were light- and temperature-dependent. Using nuclear magnetic resonance (NMR) imaging, we determined that the electrode potential regulated the diffusivity and porosity of the microbial mats. Both porosity and diffusivity were higher in the CAT mats than in the AN mats. We also used NMR spectroscopy for high-resolution quantitative metabolite analysis and found that the CAT mats had significantly higher concentrations of osmoprotectants such as betaine and trehalose. Subsequently, we performed amplicon sequencing across the V4 region of the 16S rRNA gene of incubated mats to understand the impact of electrode potential on microbial community structure. In conclusion, these data suggested that

  20. Regulation of electron transfer processes affects phototrophic mat structure and activity

    SciTech Connect

    Ha, Phuc T.; Renslow, Ryan S.; Atci, Erhan; Reardon, Patrick N.; Lindemann, Stephen R.; Fredrickson, James K.; Call, Douglas R.; Beyenal, Haluk

    2015-09-03

    Phototrophic microbial mats are among the most diverse ecosystems in nature. These systems undergo daily cycles in redox potential caused by variations in light energy input and metabolic interactions among the microbial species. In this work, solid electrodes with controlled potentials were placed under mats to study the electron transfer processes between the electrode and the microbial mat. The phototrophic microbial mat was harvested from Hot Lake, a hypersaline, epsomitic lake located near Oroville (Washington, USA). We operated two reactors: graphite electrodes were polarized at potentials of -700 mVAg/AgCl [cathodic (CAT) mat system] and +300 mVAg/AgCl [anodic (AN) mat system] and the electron transfer rates between the electrode and mat were monitored. We observed a diel cycle of electron transfer rates for both AN and CAT mat systems. Interestingly, the CAT mats generated the highest reducing current at the same time points that the AN mats showed the highest oxidizing current. To characterize the physicochemical factors influencing electron transfer processes, we measured depth profiles of dissolved oxygen (DO) and sulfide in the mats using microelectrodes. We further demonstrated that the mat-to-electrode and electrode-to-mat electron transfer rates were light- and temperature-dependent. Using nuclear magnetic resonance (NMR) imaging, we determined that the electrode potential regulated the diffusivity and porosity of the microbial mats. Both porosity and diffusivity were higher in the CAT mats than in the AN mats. We also used NMR spectroscopy for high-resolution quantitative metabolite analysis and found that the CAT mats had significantly higher concentrations of osmoprotectants such as betaine and trehalose. Subsequently, we performed amplicon sequencing across the V4 region of the 16S rRNA gene of incubated mats to understand the impact of electrode potential on microbial community structure. In conclusion, these data suggested

  1. Glass tube splitting tool

    NASA Technical Reports Server (NTRS)

    Klein, J. A.; Murray, C. D.; Stein, J. A.

    1971-01-01

    Tool accurately splits glass tubing so cuts are aligned 180 deg apart and reassembled tube forms low pressure, gastight enclosure. Device should interest industries using cylindrical closed glass containers.

  2. Failure in glass

    NASA Technical Reports Server (NTRS)

    Keeton, S. C.

    1972-01-01

    Review of state of the art concerning glass failure mechanisms and fatigue theories discusses brittle fracture in glass, fatigue mechanisms, fatigue behavior, environmental effects on failure rate, and aging.

  3. Lipid Biomarkers for a Hypersaline Microbial Mat Community

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda; Orphan, Victoria; Embaye, Tsegereda; Turk, Kendra; Kubo, Mike; Summons, Roger

    2004-01-01

    The use of lipid biomarkers and their carbon isotopic compositions are valuable tools for establishing links to ancient microbial ecosystems. Various lipids associated with specific microbial groups can serve as biomarkers for establishing organism source and function in contemporary microbial ecosystems (membrane lipids), and by analogy, potential relevance to ancient organic-rich sedimentary rocks (geolipids). As witnessed by the stromatolite record, benthic microbial mats grew in shallow water lagoonal environments. Our recent work has focused on lipid biomarker analysis of a potential analogue for such ancient mats growing in a set of hypersaline evaporation ponds at Guerrero Negro, Baja California Sur, Mexico. The aerobic, surface layer of this mat (0 to 1 mm) contained a variety of ester-bound fatty acids (FA) representing a diverse bacterial population including cyanobacteria, sulphate reducers (SRB) and heterotrophs. Biomarkers for microeukaryotes detected in this layer included sterols, C-20 polyunsaturated FA and a highly branched isoprenoid, diagnostic for diatoms. Cyanobacteria were also indicated by the presence of a diagnostic set of mid-chain methylalkanes. C-28, to C-34 wax esters (WXE) present in relatively small amounts in the upper 3 mm of the mat are considered biomarkers for green non-sulphur bacteria. Ether-bound isoprenoids were also identified although in considerably lower abundance than ester-bound FA (approx. 1:l0). These complex ether lipids included archatol, hydroxyarchaeol and a C-40 tetraether, all in small amounts. After ether cleavage with boron tribromide, the major recovered isoprenyl was a C-30:1. This C(sub 30;1) yelded squalane after hydrogenation, a known geobiomarker for hypersaline environments in ancient oils and sediments. In this mat, it represents the dominant Archaeal population. The carbon isotopic composition of biomarker lipids were generally depleted relative to the bulk organic material (delta C-13 TOC -10%). Most

  4. Weakly supervised glasses removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhicheng; Zhou, Yisu; Wen, Lijie

    2015-03-01

    Glasses removal is an important task on face recognition, in this paper, we provide a weakly supervised method to remove eyeglasses from an input face image automatically. We choose sparse coding as face reconstruction method, and optical flow to find exact shape of glasses. We combine the two processes iteratively to remove glasses more accurately. The experimental results reveal that our method works much better than these algorithms alone, and it can remove various glasses to obtain natural looking glassless facial images.

  5. Shock absorber operates over wide range

    NASA Technical Reports Server (NTRS)

    Creasy, W. K.; Jones, J. C.

    1965-01-01

    Piston-type hydraulic shock absorber, with a metered damping system, operates over a wide range of kinetic energy loading rates. It is used for absorbing shock and vibration on mounted machinery and heavy earth-moving equipment.

  6. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... absorber is a device made of paper or cotton intended to absorb moisture from the oral cavity during dental... manufacturing practice requirements of the quality system regulation in part 820 of this chapter, with...

  7. Analysis of the MAT1-1 and MAT1-2 Gene Ratio in Black Koji Molds Isolated from Meju

    PubMed Central

    Mageswari, Anbazhagan; Kim, Jeong-seon; Cheon, Kyu-Ho; Kwon, Soon-Wo

    2016-01-01

    Aspergillus luchuensis is known as an industrially important fungal species used for making fermented foods such as awamori and shochu in Japan, makgeolli and Meju in Korea, and Pu-erh tea in China. Nonetheless, this species has not yet been widely studied regarding mating-type genes. In this study, we examined the MAT1-1 and MAT1-2 gene ratio in black koji molds (A. luchuensis, Aspergillus niger, and Aspergillus tubingensis) and in Aspergillus welwitschiae isolated from Meju, a fermented soybean starting material for traditional soy sauce and soybean paste in Korea. The number of strains with the MAT1-1 locus was 2 of 23 (A. luchuensis), 6 of 13 (A. tubingensis), 21 of 28 (A. niger), and 5 of 10 (A. welwitschiae). Fungal species A. tubingensis and A. welwitschiae showed a 1 : 1 ratio of MAT1-1 and MAT1-2 mating-type loci. In contrast, A. luchuensis revealed predominance of MAT1-2 (91.3%) and A. niger of MAT1-1 (75%). We isolated and identified 2 A. luchuensis MAT1-1 strains from Meju, although all strains for making shochu in Japan are of the MAT1-2 type. These strains may be a good resource for breeding of A. luchuensis to be used in the Asian fermented-food industry. PMID:28154484

  8. Technique for Machining Glass

    NASA Technical Reports Server (NTRS)

    Rice, S. H.

    1982-01-01

    Process for machining glass with conventional carbide tools requires a small quantity of a lubricant for aluminum applied to area of glass to be machined. A carbide tool is then placed against workpiece with light pressure. Tool is raised periodically to clear work of glass dust and particles. Additional lubricant is applied as it is displaced.

  9. Glass in Class

    ERIC Educational Resources Information Center

    Greaves, Neville

    2005-01-01

    Glass is reviewed from fabrication to application, laying emphasis on the wide-ranging physics involved. This begins with liquids and solids and the way in which glasses are defined and can be demonstrated in the classroom. At the atomic level the regular structure of crystals and their irregular counterparts in glasses are explained through…

  10. Simulating the Response of a Composite Honeycomb Energy Absorber. Part 2; Full-Scale Impact Testing

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Annett, Martin S.; Jackson, Karen E.; Polanco, Michael A.

    2012-01-01

    NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark) honeycomb. The DEA has a flexible hinge that allows the honeycomb to be stowed collapsed until needed during an emergency. Evaluation of the DEA began with material characterization of the Kevlar(Registered TradeMark)-129 fabric/epoxy, and ended with a full-scale crash test of a retrofitted MD-500 helicopter. During each evaluation phase, finite element models of the test articles were developed and simulations were performed using the dynamic finite element code, LS-DYNA(Registered TradeMark). The paper will focus on simulations of two full-scale impact tests involving the DEA, a mass-simulator and a full-scale crash of an instrumented MD-500 helicopter. Isotropic (MAT24) and composite (MAT58) material models, which were assigned to DEA shell elements, were compared. Based on simulations results, the MAT58 model showed better agreement with test.

  11. Ecosystem function decays by fungal outbreaks in Antarctic microbial mats.

    PubMed

    Velázquez, David; López-Bueno, Alberto; Aguirre de Cárcer, Daniel; de los Ríos, Asunción; Alcamí, Antonio; Quesada, Antonio

    2016-03-14

    Antarctica harbours a remarkably diverse range of freshwater bodies and terrestrial ecosystems, where microbial mats are considered the most important systems in terms of biomass and metabolic capabilities. We describe the presence of lysis plaque-like macroscopic blighted patches within the predominant microbial mats on Livingston Island (Antarctic Peninsula). Those blighting circles are associated with decay in physiological traits as well as nitrogen depletion and changes in the spatial microstructure; these alterations were likely related to disruption of the biogeochemical gradients within the microbial ecosystem caused by an unusually high fungal abundance and consequent physical alterations. This phenomenon has been evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area, and decay of these ecosystems is potentially stimulated by warmer temperatures.

  12. MatSeis developer's guide:version 1.0.

    SciTech Connect

    McConnell, Lane Christopher; Young, Christopher John

    2007-05-01

    This guide is intended to enable researchers working with seismic data, but lacking backgrounds in computer science and programming, to develop seismic algorithms using the MATLAB-based MatSeis software. Specifically, it presents a series of step-by-step instructions to write four specific functions of increasing complexity, while simultaneously explaining the notation, syntax, and general program design of the functions being written. The ultimate goal is that that the user can use this guide as a jumping off point from which he or she can write new functions that are compatible with and expand the capabilities of the current MatSeis software that has been developed as part of the Ground-based Nuclear Explosion Monitoring Research and Engineering (GNEMRE) program at Sandia National Laboratories.

  13. Application of materials database (MAT.DB.) to materials education

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, Tommy L.

    1994-01-01

    Finding the right material for the job is an important aspect of engineering. Sometimes the choice is as fundamental as selecting between steel and aluminum. Other times, the choice may be between different compositions in an alloy. Discovering and compiling materials data is a demanding task, but it leads to accurate models for analysis and successful materials application. Mat. DB. is a database management system designed for maintaining information on the properties and processing of engineered materials, including metals, plastics, composites, and ceramics. It was developed by the Center for Materials Data of American Society for Metals (ASM) International. The ASM Center for Materials Data collects and reviews material property data for publication in books, reports, and electronic database. Mat. DB was developed to aid the data management and material applications.

  14. Mechanisms of mindfulness training: Monitor and Acceptance Theory (MAT).

    PubMed

    Lindsay, Emily K; Creswell, J David

    2017-02-01

    Despite evidence linking trait mindfulness and mindfulness training with a broad range of effects, still little is known about its underlying active mechanisms. Mindfulness is commonly defined as (1) the ongoing monitoring of present-moment experience (2) with an orientation of acceptance. Building on conceptual, clinical, and empirical work, we describe a testable theoretical account to help explain mindfulness effects on cognition, affect, stress, and health outcomes. Specifically, Monitor and Acceptance Theory (MAT) posits that (1), by enhancing awareness of one's experiences, the skill of attention monitoring explains how mindfulness improves cognitive functioning outcomes, yet this same skill can increase affective reactivity. Second (2), by modifying one's relation to monitored experience, acceptance is necessary for reducing affective reactivity, such that attention monitoring and acceptance skills together explain how mindfulness improves negative affectivity, stress, and stress-related health outcomes. We discuss how MAT contributes to mindfulness science, suggest plausible alternatives to the account, and offer specific predictions for future research.

  15. Ecosystem function decays by fungal outbreaks in Antarctic microbial mats

    PubMed Central

    Velázquez, David; López-Bueno, Alberto; Aguirre de Cárcer, Daniel; de los Ríos, Asunción; Alcamí, Antonio; Quesada, Antonio

    2016-01-01

    Antarctica harbours a remarkably diverse range of freshwater bodies and terrestrial ecosystems, where microbial mats are considered the most important systems in terms of biomass and metabolic capabilities. We describe the presence of lysis plaque-like macroscopic blighted patches within the predominant microbial mats on Livingston Island (Antarctic Peninsula). Those blighting circles are associated with decay in physiological traits as well as nitrogen depletion and changes in the spatial microstructure; these alterations were likely related to disruption of the biogeochemical gradients within the microbial ecosystem caused by an unusually high fungal abundance and consequent physical alterations. This phenomenon has been evidenced at a time of unprecedented rates of local warming in the Antarctic Peninsula area, and decay of these ecosystems is potentially stimulated by warmer temperatures. PMID:26972923

  16. Discrete wavelet transform FPGA design using MatLab/Simulink

    NASA Astrophysics Data System (ADS)

    Meyer-Baese, Uwe; Vera, A.; Meyer-Baese, A.; Pattichis, M.; Perry, R.

    2006-04-01

    Design of current DSP applications using state-of-the art multi-million gates devices requires a broad foundation of the engineering shlls ranging from knowledge of hardware-efficient DSP algorithms to CAD design tools. The requirement of short time-to-market, however, requires to replace the traditional HDL based designs by a MatLab/Simulink based design flow. This not only allows the over 1 million MatLab users to design FPGAs but also to by-pass the hardware design engineer leading to a significant reduction in development time. Critical however with this design flow are: (1) quality-of-results, (2) sophistication of Simulink block library, (3) compile time, (4) cost and availability of development boards, and (5) cost, functionality, and ease-of-use of the FPGA vendor provided design tools.

  17. Electrospun mats from styrene/maleic anhydride copolymers: modification with amines and assessment of antimicrobial activity.

    PubMed

    Ignatova, Milena; Stoilova, Olya; Manolova, Nevena; Markova, Nadya; Rashkov, Iliya

    2010-08-11

    New antimicrobial microfibrous electrospun mats from styrene/maleic anhydride copolymers were prepared. Two approaches were applied: (i) grafting of poly(propylene glycol) monoamine (Jeffamine® M-600) on the mats followed by formation of complex with iodine; (ii) modification of the mats with amines of 8-hydroxyquinoline or biguanide type with antimicrobial activity. Microbiological screening against S. aureus, E. coli and C. albicans revealed that both the formation of complex with iodine and the covalent attachment of 5-amino-8-hydroxyquinoline or of chlorhexidine impart high antimicrobial activity to the mats. In addition, S. aureus bacteria did not adhere to modified mats.

  18. Improving the laboratory monitoring of absorbent oil

    SciTech Connect

    V.S. Shved; S.S. Sychev; I.V. Safina; S.A. Klykov

    2009-05-15

    The performance of absorbent coal tar oil is analyzed as a function of the constituent and group composition. The qualitative and quantitative composition of the oil that ensures the required absorbent properties is determined. Operative monitoring may be based on absorbent characteristics that permit regulation of the beginning and end of regeneration.

  19. Mineralogy of iron microbial mats from loihi seamount.

    PubMed

    Toner, Brandy M; Berquó, Thelma S; Michel, F Marc; Sorensen, Jeffry V; Templeton, Alexis S; Edwards, Katrina J

    2012-01-01

    Extensive mats of Fe oxyhydroxides and associated Fe-oxidizing microbial organisms form in diverse geochemical settings - freshwater seeps to deep-sea vents - where ever opposing Fe(II)-oxygen gradients prevail. The mineralogy, reactivity, and structural transformations of Fe oxyhydroxides precipitated from submarine hydrothermal fluids within microbial mats remains elusive in active and fossil systems. In response, a study of Fe microbial mat formation at the Loihi Seamount was conducted to describe the physical and chemical characteristics of Fe-phases using extended X-ray absorption fine structure spectroscopy, powder X-ray diffraction, synchrotron radiation X-ray total scattering, low-temperature magnetic measurements, and Mössbauer spectroscopy. Particle sizes of 3.5-4.6 nm were estimated from magnetism data, and coherent scattering domain (CSD) sizes as small as 1.6 nm are indicated by pair distribution function (PDF) analysis. Disorder in the nanostructured Fe-bearing phases results in limited intermediate-range structural order: less than that of standard two-line ferrihydrite (Fh), except for the Pohaku site. The short-range ordered natural Fh (Fh(SRO)) phases were stable at 4°C in the presence of oxygen for at least 1 year and during 400°C treatment. The observed stability of the Fh(SRO) is consistent with magnetic observations that point to non-interacting nanoparticles. PDF analyses of total scattering data provide further evidence for Fh(SRO) particles with a poorly ordered silica coating. The presence of coated particles explains the small CSD for the mat minerals, as well as the stability of the minerals over time and against heating. The mineral properties observed here provide a starting point from which progressively older and more extensively altered Fe deposits may be examined, with the ultimate goal of improved interpretation of past biogeochemical conditions and diagenetic processes.

  20. Mineralogy of Iron Microbial Mats from Loihi Seamount

    PubMed Central

    Toner, Brandy M.; Berquó, Thelma S.; Michel, F. Marc; Sorensen, Jeffry V.; Templeton, Alexis S.; Edwards, Katrina J.

    2011-01-01

    Extensive mats of Fe oxyhydroxides and associated Fe-oxidizing microbial organisms form in diverse geochemical settings – freshwater seeps to deep-sea vents – where ever opposing Fe(II)-oxygen gradients prevail. The mineralogy, reactivity, and structural transformations of Fe oxyhydroxides precipitated from submarine hydrothermal fluids within microbial mats remains elusive in active and fossil systems. In response, a study of Fe microbial mat formation at the Loihi Seamount was conducted to describe the physical and chemical characteristics of Fe-phases using extended X-ray absorption fine structure spectroscopy, powder X-ray diffraction, synchrotron radiation X-ray total scattering, low-temperature magnetic measurements, and Mössbauer spectroscopy. Particle sizes of 3.5–4.6 nm were estimated from magnetism data, and coherent scattering domain (CSD) sizes as small as 1.6 nm are indicated by pair distribution function (PDF) analysis. Disorder in the nanostructured Fe-bearing phases results in limited intermediate-range structural order: less than that of standard two-line ferrihydrite (Fh), except for the Pohaku site. The short-range ordered natural Fh (FhSRO) phases were stable at 4°C in the presence of oxygen for at least 1 year and during 400°C treatment. The observed stability of the FhSRO is consistent with magnetic observations that point to non-interacting nanoparticles. PDF analyses of total scattering data provide further evidence for FhSRO particles with a poorly ordered silica coating. The presence of coated particles explains the small CSD for the mat minerals, as well as the stability of the minerals over time and against heating. The mineral properties observed here provide a starting point from which progressively older and more extensively altered Fe deposits may be examined, with the ultimate goal of improved interpretation of past biogeochemical conditions and diagenetic processes. PMID:22485113

  1. AM2 Brickwork Pattern Evaluation with Refurbished Matting

    DTIC Science & Technology

    2015-08-01

    and Jeb S. Tingle Geotechnical and Structures Laboratory U.S. Army Engineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS ...Waterways Experiment Station in Vicksburg, MS from 1961 through 1971, with major procurements beginning in 1965. The original AM2 mat has been modified...from a local source in Vicksburg, MS , and was subjected to laboratory tests including grain-size analysis (hydrometer), Atterberg Limits, modified

  2. Halotaxis of cyanobacteria in an intertidal hypersaline microbial mat.

    PubMed

    Kohls, Katharina; Abed, Raeid M M; Polerecky, Lubos; Weber, Miriam; de Beer, Dirk

    2010-03-01

    An intertidal hypersaline cyanobacterial mat from Abu Dhabi (United Arab Emirates) exhibited a reversible change in its surface colour within several hours upon changes in salinity of the overlying water. The mat surface was orange-reddish at salinities above 15% and turned dark green at lower salinities. We investigated this phenomenon using a polyphasic approach that included denaturing gradient gel electrophoresis, microscopy, high-performance liquid chromatography, hyperspectral imaging, absorption spectroscopy, oxygen microsensor measurements and modelling of salinity dynamics. Filaments of Microcoleus chthonoplastes, identified based on 16S rRNA sequencing and morphology, were found to migrate up and down when salinity was decreased below or increased above 15%, respectively, causing the colour change of the mat uppermost layer. Migration occurred in light and in the dark, and could be induced by different salts, not only NaCl. The influence of salinity-dependent and independent physico-chemical parameters, such as water activity, oxygen solubility, H2S, gravity and light, was excluded, indicating that the observed migration was due to a direct response to salt stress. We propose to term this salinity-driven cyanobacterial migration as 'halotaxis', a process that might play a vital role in the survival of cyanobacteria in environments exposed to continuous salinity fluctuations such as intertidal flats.

  3. Flow visualization study of the HiMAT RPRV

    NASA Technical Reports Server (NTRS)

    Lorincz, D. J.

    1980-01-01

    Water tunnel studies were performed to qualitatively define the flow field of the highly maneuverable aircraft technology remotely piloted research vehicle (HiMAT RPRV). Particular emphasis was placed on defining the vortex flows generated at high angles of attack. The flow visualization tests were conducted in the Northrop water tunnel using a 1/15 scale model of the HiMAT RPRV. Flow visualization photographs were obtained for angles of attack up to 40 deg and sideslip angles up to 5 deg. The HiMAT model was investigated in detail to determine the canard and wing vortex flow field development, vortex paths, and vortex breakdown characteristics as a function of angle of attack and sideslip. The presence of the canard caused the wing vortex to form further outboard and delayed the breakdown of the wing vortex to higher angles of attack. An increase in leading edge camber of the maneuver configuration delayed both the formation and the breakdown of the wing and canard vortices. Additional tests showed that the canard vortex was sensitive to variations in inlet mass flow ratio and canard flap deflection angle.

  4. Novel wound dressing based on nanofibrous PHBV-keratin mats.

    PubMed

    Yuan, Jiang; Geng, Jia; Xing, Zhicai; Shim, Kyoung-Jin; Han, Insook; Kim, Jung-Chul; Kang, Inn-Kyu; Shen, Jian

    2015-09-01

    Keratin is an important protein used for wound healing and tissue recovery. In this study, keratin was first extracted from raw materials and chemically modified to obtain stable keratin (m-keratin). The raw and m-keratin were examined by Raman spectroscopy. The molecular weight of the m-keratin was analysed by SDS-PAGE. The m-keratin was then blended with poly(hydroxybutylate-co-hydroxyvalerate) (PHBV) and electrospun to afford nanofibrous mats. These mats were characterized by field emission scanning electron microscopy (FE-SEM), electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM). From the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) data, it was found that introduction of keratin enhanced cell proliferation. From wound-healing test and histological examination results, it was shown that the composite mats accelerated wound recovery remarkably as compared to the PHBV control. It was concluded that PHBV-keratin may be a good candidate as a wound dressing.

  5. Simulated Carbon Cycling in a Model Microbial Mat.

    NASA Astrophysics Data System (ADS)

    Decker, K. L.; Potter, C. S.

    2006-12-01

    We present here the novel addition of detailed organic carbon cycling to our model of a hypersaline microbial mat ecosystem. This ecosystem model, MBGC (Microbial BioGeoChemistry), simulates carbon fixation through oxygenic and anoxygenic photosynthesis, and the release of C and electrons for microbial heterotrophs via cyanobacterial exudates and also via a pool of dead cells. Previously in MBGC, the organic portion of the carbon cycle was simplified into a black-box rate of accumulation of simple and complex organic compounds based on photosynthesis and mortality rates. We will discuss the novel inclusion of fermentation as a source of carbon and electrons for use in methanogenesis and sulfate reduction, and the influence of photorespiration on labile carbon exudation rates in cyanobacteria. We will also discuss the modeling of decomposition of dead cells and the ultimate release of inorganic carbon. The detailed modeling of organic carbon cycling is important to the accurate representation of inorganic carbon flux through the mat, as well as to accurate representation of growth models of the heterotrophs under different environmental conditions. Because the model ecosystem is an analog of ancient microbial mats that had huge impacts on the atmosphere of early earth, this MBGC can be useful as a biological component to either early earth models or models of other planets that potentially harbor life.

  6. Nitrogen Fixation (Acetylene Reduction) Associated with Duckweed (Lemnaceae) Mats

    PubMed Central

    Zuberer, D. A.

    1982-01-01

    Duckweed (Lemnaceae) mats in Texas and Florida were investigated, using the acetylene reduction assay, to determine whether nitrogen fixation occurred in these floating aquatic macrophyte communities. N2-fixing microorganisms were enumerated by plating or most-probable-number techniques, using appropriate N-free media. Results of the investigations indicated that substantial N2-fixation (C2H2) was associated with duckweed mats in Texas and Florida. Acetylene reduction values ranged from 1 to 18 μmol of C2H4 g (dry weight)−1 day−1 for samples incubated aerobically in light. Dark N2 fixation was always two- to fivefold lower. 3-(3,4-Dichlorophenyl)-1,1-dimethylurea (7 to 10 μM) reduced acetylene reduction to levels intermediate between light and dark incubation. Acetylene reduction was generally greatest for samples incubated anaerobically in the light. It was estimated that 15 to 20% of the N requirement of the duckweed could be supplied through biological nitrogen fixation. N2-fixing heterotrophic bacteria (105 cells g [wet weight]−1 and cyanobacteria (105 propagules g [wet weight]−1 were associated with the duckweed mats. Azotobacter sp. was not detected in these investigations. One diazotrophic isolate was classified as Klebsiella. PMID:16345992

  7. Interlocking mats support drilling rig on frozen swamp

    SciTech Connect

    Not Available

    1991-04-15

    This paper discusses how a company employed a unique mat system to reduce environmental impact and to support the drilling rig on its Astosch No. 1 exploratory well at Granite Point in the Trading Bay Wildlife Refuge. The site is on the west side of Cook Inlet. During winter, the travel time from Anchorage to the base camp near the Tyonek Indian village was 5 hr by ice road or 45 min by fixed wing aircraft. Eighteen miles of existing gravel roads were used from this base camp to the edge of the frozen muskeg swamp, and from there, they constructed 7 miles of ice road to the well site. They constructed a snow and ice pad with two impermeable liners and then installed Uni-Mat International Inc.'s patented interlocking mats for the final foundation. After moving in the rig, a snow berm was built around the perimeter of the location and an impermeable liner was then draped and secured over the berm.

  8. Biogeochemical cycles of carbon, sulfur, and free oxygen in a microbial mat

    NASA Technical Reports Server (NTRS)

    Canfield, Donald E.; Des Marais, David J.

    1993-01-01

    Complete budgets for carbon and oxygen have been constructed for cyanobacterial mats dominated by Microcoleus chthonoplastes from the evaporating ponds of a salt works. We infer from the data the various sinks for O2 as well as the sources of carbon for primary production. Although seasonal variability exists, a major percentage of the O2 produced during the day did not diffuse out of the mat but was used within the mat to oxidize both organic carbon and the sulfide produced by sulfate reduction. At night, most of the O2 that diffused into the mat was used to oxidize sulfide, with O2 respiration of minor importance. During the day, the internal mat processes of sulfate reduction and O2 respiration generated as much or more inorganic carbon (DIC) for primary production as diffusion into the mat. Oxygenic photosynthesis was the most important process of carbon fixation. At night, the DIC lost from the mat was mostly from sulfate reduction. Elemental fluxes across the mat/brine interface indicated that carbon with an oxidation state of greater than zero was taken up by the mat during the day and liberated from the mat at night. Overall, carbon with an average oxidation state of near zero accumulated in the mat. Both carbon fixation and carbon oxidation rates varied with temperature by a similar amount.

  9. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  10. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  11. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  12. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  13. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru; Watson, E. Bruce; Acocella, John

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  14. Oxynitride glass production procedure

    DOEpatents

    Weidner, Jerry R.; Schuetz, Stanley T.; O'Brien, Michael H.

    1991-01-01

    The invention is a process for the preparation of high quality oxynitride glasses without resorting to high pressures. Nitrogen-containing compounds such as Si.sub.3 N.sub.4 are first encapsulated in a low melting temperature glass. Particles of the encapsulated nitrogen-containing compound are mixed with other oxide glass-formers and melted in an atmosphere of flowing nitrogen and in the presence of buffering gas to form the oxynitride glass. Glasses containing up to 15 at % nitrogen have been prepared by this method.

  15. Mucoadhesive electrospun chitosan-based nanofibre mats for dental caries prevention.

    PubMed

    Samprasit, Wipada; Kaomongkolgit, Ruchadaporn; Sukma, Monrudee; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2015-03-06

    The mucoadhesive electrospun nanofibre mats were developed using chitosan (CS) and thiolated chitosan (CS-SH) as mucoadhesive polymers. Garcinia mangostana (GM) extract was incorporated into nanofibre mats. The antibacterial activity in the single and combined agents was evaluated against dental caries pathogens. The morphology of mats was observed using SEM. The mats were evaluated for GM extract amount, mucoadhesion, in vitro release, antibacterial activity and cytotoxicity. The mucoadhesion and antibacterial activity were determined in healthy human volunteers. The prepared mats were in nanoscale with good physical and mucoadhesive properties. The CS-SH caused the higher mucoadhesion. All mats rapidly released active substances, which had the synergistic antibacterial activity. In addition, the reduction of bacteria and good mucoadhesion in the oral cavity occurred without cytotoxicity. The results suggest that mats have the potential to be mucoadhesive dosage forms to maintain oral hygiene by reducing the bacterial growth that causes the dental caries.

  16. Development and characterization of a thinner binary mask absorber for 22-nm node and beyond

    NASA Astrophysics Data System (ADS)

    Faure, Tom; Badger, Karen; Kindt, Louis; Kodera, Yutaka; Komizo, Toru; Kondo, Shinpei; Mizoguchi, Takashi; Nemoto, Satoru; Seki, Kazunori; Senna, Tasuku; Wistrom, Richard; Zweber, Amy; Nishikawa, Kazuhiro; Inazuki, Yukio; Yoshikawa, Hiroki

    2010-09-01

    The lithography challenges posed by the 22 nm node continue to place stringent requirements on photomasks. The dimensions of the mask features continue to shrink more deeply into the sub-wavelength scale. In this regime residual mask electromagnetic field (EMF) effects due to mask topography can degrade the imaging performance of critical mask patterns by degrading the common lithography process window and by magnifying the impact of mask errors or MEEF. Based on this, an effort to reduce the mask topography effect by decreasing the thickness of the mask absorber was conducted. In this paper, we will describe the results of our effort to develop and characterize a binary mask substrate with an absorber that is approximately 20-25% thinner than the absorber on the current Opaque MoSi on Glass (OMOG) binary mask substrate. For expediency, the thin absorber development effort focused on using existing absorber materials and deposition methods. It was found that significant changes in film composition and structure were needed to obtain a substantially thinner blank while maintaining an optical density of 3.0 at 193 nm. Consequently, numerous studies to assess the mask making performance of the thinner absorber material were required and will be described. During these studies several significant mask making advantages of the thin absorber were discovered. The lower film stress and thickness of the new absorber resulted in improved mask flatness and up to a 60% reduction in process-induced mask pattern placement change. Improved cleaning durability was another benefit. Furthermore, the improved EMF performance of the thinner absorber [1] was found to have the potential to relieve mask manufacturing constraints on minimum opaque assist feature size and opaque corner to corner gap. Based on the results of evaluations performed to date, the thinner absorber has been found to be suitable for use for fabricating masks for the 22 nm node and beyond.

  17. Carbon dioxide absorbents for rebreather diving.

    PubMed

    Pennefather, John

    2016-09-01

    Firstly I would like to thank SPUMS members for making me a Life Member of SPUMS; I was surprised and greatly honoured by the award. I also want to confirm and expand on the findings on carbon dioxide absorbents reported by David Harvey et al. For about 35 years, I was the main player in deciding which absorbent went into Australian Navy and Army diving sets. On several occasions, suppliers of absorbents to the anaesthesia market tried to supply the Australian military market. On no occasion did they provide absorbent that came close to the minimum absorbent capacity required, generally being 30-40% less efficient than diving-grade absorbents. Because I regard lives as being more important than any likely dollar saving, the best absorbent was always selected unless two suppliers provided samples with the same absorbent capacity. On almost every occasion, there was a clear winner and cost was never considered. I suggest the same argument for the best absorbent should be used by members and their friends who dive using rebreather sets. I make this point because of my findings on a set that was brought to me after the death of its owner. The absorbent was not the type or grain size recommended by the manufacturer of the set and did not resemble any of the diving grade absorbents I knew of. I suspected by its appearance that it was anaesthetic grade absorbent. When I tested the set, the absorbent system failed very quickly so it is likely that carbon dioxide toxicity contributed to his death. The death was not the subject of an inquest and I have no knowledge of how the man obtained the absorbent. Possibly there was someone from an operating theatre staff who unintentionally caused their friend's death by supplying him with 'borrowed absorbent'. I make this point as I would like to discourage members from making a similar error.

  18. Studying Microbial Mat Functioning Amidst "Unexpected Diversity": Methodological Approaches and Initial Results from Metatranscriptomes of Mats Over Diel cycles, iTags from Long Term Manipulations, and Biogeochemical Cycling in Simplified Microbial Mats Constructed from Cultures

    NASA Astrophysics Data System (ADS)

    Bebout, B.; Bebout, L. E.; Detweiler, A. M.; Everroad, R. C.; Lee, J.; Pett-Ridge, J.; Weber, P. K.

    2014-12-01

    Microbial mats are famously amongst the most diverse microbial ecosystems on Earth, inhabiting some of the most inclement environments known, including hypersaline, dry, hot, cold, nutrient poor, and high UV environments. The high microbial diversity of microbial mats makes studies of microbial ecology notably difficult. To address this challenge, we have been using a combination of metagenomics, metatranscriptomics, iTags and culture-based simplified microbial mats to study biogeochemical cycling (H2 production, N2 fixation, and fermentation) in microbial mats collected from Elkhorn Slough, Monterey Bay, California. Metatranscriptomes of microbial mats incubated over a diel cycle have revealed that a number of gene systems activate only during the day in Cyanobacteria, while the remaining appear to be constitutive. The dominant cyanobacterium in the mat (Microcoleus chthonoplastes) expresses several pathways for nitrogen scavenging undocumented in cultured strains, as well as the expression of two starch storage and utilization cycles. Community composition shifts in response to long term manipulations of mats were assessed using iTags. Changes in community diversity were observed as hydrogen fluxes increased in response to a lowering of sulfate concentrations. To produce simplified microbial mats, we have isolated members of 13 of the 15 top taxa from our iTag libraries into culture. Simplified microbial mats and simple co-cultures and consortia constructed from these isolates reproduce many of the natural patterns of biogeochemical cycling in the parent natural microbial mats, but against a background of far lower overall diversity, simplifying studies of changes in gene expression (over the short term), interactions between community members, and community composition changes (over the longer term), in response to environmental forcing.

  19. Developing photorefractive glass composites

    NASA Astrophysics Data System (ADS)

    Duignan, Jason P.; Taylor, Lesley L.; Cook, Gary

    2002-01-01

    The production of a transparent photorefractive glass composite would offer a useful alternative to bulk crystal materials. We aim to produce such a material by incorporating single domain photorefractive Fe:LiNbO3 particles into a refractive index matched glass host. This glass host is also required to be chemically compatible with the photorefractive material. This compatibility will ensure that the Fe:LiNbO3 particles added to the host glass will remain in the intended crystalline phase and not simply dissolve in the glass. Due to the high refractive index of the Fe:LiNbO3 (no equals 2.35 532 nm), producing a chemically compatible and refractive index matched glass host is technically challenging. By examining common Tellurite, Bismuthate, and Gallate glasses as a starting point and then developing new and hybrid glasses, we have succeeded in producing a chemically compatible glass host and also a refractive index matched glass host. We have produced preliminary glass composite samples which contain a large amount of Fe:LiNbO3. We are currently able to retain nearly 90% of the incorporated Fe:LiNbO3 in the correct crystalline phase, a substantial improvement over previous work conducted in this area in recent years. In this paper we present our progress and findings in this area.

  20. Acoustics of glass harmonicas

    NASA Astrophysics Data System (ADS)

    Rossing, Thomas D.

    2004-05-01

    Glass musical instruments are probably as old as glassmaking. At least as early as the 17th century it was discovered that wine glasses, when rubbed with a wet finger, produced a musical tone. A collection of glasses played in this manner is called a glass harp. Another type of glass harmonica, called the armonica by its inventor Benjamin Franklin, employs glass bowls or cups turned by a horizontal axle, so the performer need only touch the rim of the bowls as they rotate to set them into vibration. We discuss the modes of vibration of both types of glass harmonica, and describe the different sounds that are emitted by rubbing, tapping, or bowing them. Rubbing with a wet finger tends to excite only the (2,0) mode and its harmonics through a ``stick-slip'' process, while tapping excites the other modes as well.

  1. A polarization-independent broadband terahertz absorber

    SciTech Connect

    Shi, Cheng; Zang, XiaoFei E-mail: ymzhu@usst.edu.cn; Wang, YiQiao; Chen, Lin; Cai, Bin; Zhu, YiMing E-mail: ymzhu@usst.edu.cn

    2014-07-21

    A highly efficient broadband terahertz absorber is designed, fabricated, and experimentally as well as theoretically evaluated. The absorber comprises a heavily doped silicon substrate and a well-designed two-dimensional grating. Due to the destructive interference of waves and diffraction, the absorber can achieve over 95% absorption in a broad frequency range from 1 to 2 THz and for angles of incidence from 0° to 60°. Such a terahertz absorber is also polarization-independent due to its symmetrical structure. This omnidirectional and broadband absorber have potential applications in anti-reflection coatings, imaging systems, and so on.

  2. On the use of a loudspeaker for measuring the viscoelastic properties of sound absorbing materials.

    PubMed

    Doutres, Olivier; Dauchez, Nicolas; Génevaux, Jean-Michel; Lemarquand, Guy

    2008-12-01

    This paper investigates the feasibility to use an electrodynamic loudspeaker to determine viscoelastic properties of sound-absorbing materials in the audible frequency range. The loudspeaker compresses the porous sample in a cavity, and a measurement of its electrical impedance allows one to determine the mechanical impedance of the sample: no additional sensors are required. Viscoelastic properties of the material are then estimated by inverting a 1D Biot model. The method is applied to two sound-absorbing materials (glass wool and polymer foam). Results are in good agreement with the classical compression quasistatic method.

  3. Optical properties of solid-core photonic crystal fibers filled with nonlinear absorbers.

    PubMed

    Butler, James J; Bowcock, Alec S; Sueoka, Stacey R; Montgomery, Steven R; Flom, Steven R; Friebele, E Joseph; Wright, Barbara M; Peele, John R; Pong, Richard G S; Shirk, James S; Hu, Jonathan; Menyuk, Curtis R; Taunay, T F

    2013-09-09

    A theoretical and experimental investigation of the transmission of solid-core photonic crystal fibers (PCFs) filled with nonlinear absorbers shows a sharp change in the threshold for optical limiting and in leakage loss as the refractive index of the material in the holes approaches that of the glass matrix. Theoretical calculations of the mode profiles and leakage loss of the PCF are in agreement with experimental results and indicate that the change in limiting response is due to the interaction of the evanescent field of the guided mode with the nonlinear absorbers in the holes.

  4. Phototrophic phylotypes dominate mesothermal microbial mats associated with hot springs in Yellowstone National Park.

    PubMed

    Ross, Kimberly A; Feazel, Leah M; Robertson, Charles E; Fathepure, Babu Z; Wright, Katherine E; Turk-Macleod, Rebecca M; Chan, Mallory M; Held, Nicole L; Spear, John R; Pace, Norman R

    2012-07-01

    The mesothermal outflow zones (50-65°C) of geothermal springs often support an extensive zone of green and orange laminated microbial mats. In order to identify and compare the microbial inhabitants of morphologically similar green-orange mats from chemically and geographically distinct springs, we generated and analyzed small-subunit ribosomal RNA (rRNA) gene amplicons from six mesothermal mats (four previously unexamined) in Yellowstone National Park. Between three and six bacterial phyla dominated each mat. While many sequences bear the highest identity to previously isolated phototrophic genera belonging to the Cyanobacteria, Chloroflexi, and Chlorobi phyla, there is also frequent representation of uncultured, unclassified members of these groups. Some genus-level representatives of these dominant phyla were found in all mats, while others were unique to a single mat. Other groups detected at high frequencies include candidate divisions (such as the OP candidate clades) with no cultured representatives or complete genomes available. In addition, rRNA genes related to the recently isolated and characterized photosynthetic acidobacterium "Candidatus Chloracidobacterium thermophilum" were detected in most mats. In contrast to microbial mats from well-studied hypersaline environments, the mesothermal mats in this study accrue less biomass and are substantially less diverse, but have a higher proportion of known phototrophic organisms. This study provides sequences appropriate for accurate phylogenetic classification and expands the molecular phylogenetic survey of Yellowstone microbial mats.

  5. Active ingredient-containing chitosan/polycaprolactone nonwoven mats: characterizations and their functional assays.

    PubMed

    Bai, Meng-Yi; Chou, Tz-Chong; Tsai, Jie-Chang; Yang, Hui-Ching

    2013-01-01

    This study demonstrates a facile method developed to generate a chitosan/polycaprolactone (CS/PCL) nonwoven mat. All nonwoven mats are composed of microfibers with an average diameter of 2.51±0.69 μm. The X-ray photoelectron spectroscopy data indicate that positively charged nitrogen was generated on the surface of the mats after undergoing CS coating. By using a non-contacting electrostatic voltmeter, we determined that the nonwoven mats exhibited a positive potential and the charge density of the CS/PCL nonwoven mat was in proportion to the thickness of the CS overlayer. Moreover, platelet aggregation and anti-bacterial ability were enhanced by the CS/PCL nonwoven mat as compared to that of PCL nonwoven mat alone. The enhancements of the CS/PCL nonwoven mat on platelet aggregation are further promoted by incorporating a 1mM calcium ion in its CS overlayer. We also find that the addition of tea tree oil in the CS overlayer significantly inhibited LPS-induced nitrite formation in Raw 264.7 macrophages. In conclusion, our CS/PCL nonwoven mat possesses pharmacological effects including an increase of platelet aggregation, anti-bacterial, anti-adhesive, and anti-inflammatory activities. The performance of this CS/PCL nonwoven mat can be further promoted by incorporating active compounds to exert therapeutic effects in wound healing.

  6. Dynamics of archaea at fine spatial scales in Shark Bay mat microbiomes

    PubMed Central

    Wong, Hon Lun; Visscher, Pieter T.; White III, Richard Allen; Smith, Daniela-Lee; Patterson, Molly M.; Burns, Brendan P.

    2017-01-01

    The role of archaea in microbial mats is poorly understood. Delineating the spatial distribution of archaea with mat depth will enable resolution of putative niches in these systems. In the present study, high throughput amplicon sequencing was undertaken in conjunction with analysis of key biogeochemical properties of two mats (smooth and pustular) from Shark Bay, Australia. One-way analysis of similarity tests indicated the archaeal community structures of smooth and pustular mats were significantly different (global R = 1, p = 0.1%). Smooth mats possessed higher archaeal diversity, dominated by Parvarchaeota. The methanogenic community in smooth mats was dominated by hydrogenotrophic Methanomicrobiales, as well as methylotrophic Methanosarcinales, Methanococcales, Methanobacteriales and Methanomassiliicoccaceae. Pustular mats were enriched with Halobacteria and Parvarchaeota. Key metabolisms (bacterial and archaeal) were measured, and the rates of oxygen production/consumption and sulfate reduction were up to four times higher in smooth than in pustular mats. Methane production peaked in the oxic layers and was up to seven-fold higher in smooth than pustular mats. The finding of an abundance of anaerobic methanogens enriched at the surface where oxygen levels were highest, coupled with peak methane production in the oxic zone, suggests putative surface anoxic niches in these microbial mats.

  7. Liquid crystal tunable metamaterial absorber.

    PubMed

    Shrekenhamer, David; Chen, Wen-Chen; Padilla, Willie J

    2013-04-26

    We present an experimental demonstration of electronically tunable metamaterial absorbers in the terahertz regime. By incorporation of active liquid crystal into strategic locations within the metamaterial unit cell, we are able to modify the absorption by 30% at 2.62 THz, as well as tune the resonant absorption over 4% in bandwidth. Numerical full-wave simulations match well to experiments and clarify the underlying mechanism, i.e., a simultaneous tuning of both the electric and magnetic response that allows for the preservation of the resonant absorption. These results show that fundamental light interactions of surfaces can be dynamically controlled by all-electronic means and provide a path forward for realization of novel applications.

  8. Oxalate: Effect on calcium absorbability

    SciTech Connect

    Heaney, R.P.; Weaver, C.M. )

    1989-10-01

    Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species.

  9. Plasticity in Cu(111)/Cu46Zr54 glass nanolaminates under uniaxial compression

    NASA Astrophysics Data System (ADS)

    Arman, B.; Brandl, C.; Luo, S. N.; Germann, T. C.; Misra, A.; ćaǧin, T.

    2011-08-01

    We perform large-scale molecular dynamics simulations to investigate plasticity in Cu/Cu46Zr54 glass nanolaminates under uniaxial compression. Partial and full dislocations are observed in the Cu layers, and screw dislocations are seen near the amorphous-crystalline interfaces (ACIs). Nucleation of shear bands in a glass layer is directly induced by the dislocations in the neighboring crystalline Cu layer through ACIs, and they grow from the ACIs into the glass layer and absorb ambient shear transformation zones. Plasticity in the glass layers is realized via pronounced, stable shear banding.

  10. GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSILICATE GLASS FOR PLUTONIUM DISPOSITION

    SciTech Connect

    Crawford, C; James Marra, J; Ned Bibler, N

    2007-02-12

    The Department of Energy Office of Environmental Management (DOE/EM) plans to conduct the Plutonium Disposition Project at the Savannah River Site (SRS) in Aiken, SC, to disposition excess weapons-usable plutonium. A plutonium glass waste form is a leading candidate for immobilization of the plutonium for subsequent disposition in a geologic repository. The objectives of this present task were to fabricate plutonium-loaded lanthanide borosilicate (LaBS) Frit B glass and perform testing to provide near-term data that will increase confidence that LaBS glass product is suitable for disposal in the proposed Federal Repository. Specifically, testing was conducted in an effort to provide data to Yucca Mountain Project (YMP) personnel for use in performance assessment calculations. Plutonium containing LaBS glass with the Frit B composition with a 9.5 wt% PuO{sub 2} loading was prepared for testing. Glass was prepared to support glass durability testing via the ASTM Product Consistency Testing (PCT) at Savannah River National Laboratory (SRNL). The glass was characterized with X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) prior to performance testing. This characterization revealed some crystalline PuO{sub 2} inclusions with disk-like morphology present in the as fabricated, quench-cooled glass. A series of PCTs was conducted at SRNL with varying exposed surface area and test durations. Filtered leachates from these tests were analyzed to determine the dissolved concentrations of key elements. The leachate solutions were also ultrafiltered to quantify colloid formation. Leached solids from select PCTs were examined in an attempt to evaluate the Pu and neutron absorber release behavior from the glass and to investigate formation of alteration phases on the glass surface. A series of PCTs was conducted at 90 C in ASTM Type 1 water to compare the Pu LaBS Frit B glass durability to current requirements for High

  11. Thin films of copper antimony sulfide: A photovoltaic absorber material

    SciTech Connect

    Ornelas-Acosta, R.E.; Shaji, S.; Avellaneda, D.; Castillo, G.A.; Das Roy, T.K.; Krishnan, B.

    2015-01-15

    Highlights: • CuSbS{sub 2} thin films were prepared by heating Sb{sub 2}S{sub 3}/Cu layers. • Analyzed the structure, composition, optical, and electrical properties. • PV structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag were formed at different conditions. • The PV parameters (J{sub sc}, V{sub oc}, and FF) were evaluated from the J–V characteristics. • J{sub sc}: 0.52–3.20 mA/cm{sup 2}, V{sub oc}:187–323 mV, FF: 0.27–0.48 were obtained. - Abstract: In this work, we report preparation and characterization of CuSbS{sub 2} thin films by heating glass/Sb{sub 2}S{sub 3}/Cu layers and their use as absorber material in photovoltaic structures: glass/SnO{sub 2}:F/n-CdS/p-CuSbS{sub 2}/C/Ag. The Sb{sub 2}S{sub 3} thin films of 600 nm were prepared by chemical bath deposition on which copper thin films of 50 nm were thermally evaporated, and the glass/Sb{sub 2}S{sub 3}/Cu multilayers were heated in vacuum at different temperatures. X-ray diffraction analysis showed the formation of orthorhombic CuSbS{sub 2} after heating the precursor layers. Studies on identification and chemical state of the elements were done using X-ray photoelectron spectroscopy. The optical band gap of the CuSbS{sub 2} thin films was 1.55 eV and the thin films were photoconductive. The photovoltaic parameters of the devices using CuSbS{sub 2} as absorber and CdS as window layer were evaluated from the J–V curves, yielding J{sub sc}, V{sub oc}, and FF values in the range of 0.52–3.20 mA/cm{sup 2}, 187–323 mV, and 0.27–0.48, respectively, under illumination of AM1.5 radiation.

  12. Reversing Glass Wettability

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Smith, J. E., Jr.; Kaukler, W. F.

    1985-01-01

    Treatment reverses wettability of glassware: Liquids that normally wet glass no longer do, and those that do not wet glass are made to do so. Useful in research on container effects in nucleation and growth of secondary phase from solution. Treatment consists of spreading 3 percent (by weight) solution of silicone oil in hexane isomers over glass, drying in air, and curing at 300 degrees C in vacuum for one hour.

  13. Diamond turning of glass

    SciTech Connect

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  14. Diel Metagenomics and Metatranscriptomics of Elkhorn Slough Hypersaline Microbial Mat

    NASA Astrophysics Data System (ADS)

    Lee, J.; Detweiler, A. M.; Everroad, R. C.; Bebout, L. E.; Weber, P. K.; Pett-Ridge, J.; Bebout, B.

    2014-12-01

    To understand the variation in gene expression associated with the daytime oxygenic phototrophic and nighttime fermentation regimes seen in hypersaline microbial mats, a contiguous mat piece was subjected to sampling at regular intervals over a 24-hour diel period. Additionally, to understand the impact of sulfate reduction on biohydrogen consumption, molybdate was added to a parallel experiment in the same run. 4 metagenome and 12 metatranscriptome Illumina HiSeq lanes were completed over day / night, and control / molybdate experiments. Preliminary comparative examination of noon and midnight metatranscriptomic samples mapped using bowtie2 to reference genomes has revealed several notable results about the dominant mat-building cyanobacterium Microcoleus chthonoplastes PCC 7420. Dominant cyanobacterium M. chthonoplastes PCC 7420 shows expression in several pathways for nitrogen scavenging, including nitrogen fixation. Reads mapped to M. chthonoplastes PCC 7420 shows expression of two starch storage and utilization pathways, one as a starch-trehalose-maltose-glucose pathway, another through UDP-glucose-cellulose-β-1,4 glucan-glucose pathway. The overall trend of gene expression was primarily light driven up-regulation followed by down-regulation in dark, while much of the remaining expression profile appears to be constitutive. Co-assembly of quality-controlled reads from 4 metagenomes was performed using Ray Meta with progressively smaller K-mer sizes, with bins identified and filtered using principal component analysis of coverages from all libraries and a %GC filter, followed by reassembly of the remaining co-assembly reads and binned reads. Despite having relatively similar abundance profiles in each metagenome, this binning approach was able to distinctly resolve bins from dominant taxa, but also sulfate reducing bacteria that are desired for understanding molybdate inhibition. Bins generated from this iterative assembly process will be used for downstream

  15. Matériaux pour la combustion catalytique

    NASA Astrophysics Data System (ADS)

    Lunot, C.

    2002-04-01

    La combustion catalytique est l'une des technologies les plus prometteuses pour réaliser une combustion ultra-propre des hydrocarbures et notamment du gaz naturel. Aujourd'hui, cependant, les produits commerciaux utilisant cette technologie sont peu nombreux et le plus souvent réservés à des applications basse température (500-700°C) à cause de la limitation liée à la durée de vie des catalyseurs utilisés (métaux précieux). Le développement de cette technologie est donc intimement lié à des défis “matériaux”, et notamment à l'obtention de catalyseurs actifs et durables au moins plusieurs milliers d'heures à des températures comprises entre 700 et 1 100°C. Or les catalyseurs de type métaux précieux, très actifs y compris à basse température, ont une durée de vie (maintien de leur activité catalytique dans le temps) d'autant plus limitée que la température de l'application est élevée. A l'inverse, les catalyseurs de type pérovskite ou hexaaluminate, dont la durée de vie à haute température est satisfaisante, présentent une activité plus faible qui rend notamment l'amorçage de la combustion catalytique délicate. C'est pourquoi les solutions potentielles sont à rechercher non seulement du côté matériaux de catalyseurs mais aussi du côté ingénierie et conception des matériels associés.

  16. Spectroscopic analysis (FTIR, Raman) of water in mafic and intermediate glasses and glass inclusions

    NASA Astrophysics Data System (ADS)

    Mercier, Maxime; Muro, Andrea Di; Métrich, Nicole; Giordano, Daniele; Belhadj, Olfa; Mandeville, Charles W.

    2010-10-01

    Micro-Raman spectroscopy, even though a very promising technique, is not still routinely applied to analyse H 2O in silicate glasses. The accuracy of Raman water determinations critically depends on the capability to predict and take into account both the matrix effects (bulk glass composition) and the analytical conditions on band intensities. On the other hand, micro-Fourier transform infrared spectroscopy is commonly used to measure the hydrous absorbing species (e.g., hydroxyl OH - and molecular H 2O) in natural glasses, but requires critical assumptions for the study of crystal-hosted glasses. Here, we quantify for the first time the matrix effect of Raman external calibration procedures for the quantification of the total H 2O content (H 2O T = OH - + H 2O m) in natural silicate glasses. The procedures are based on the calibration of either the absolute (external calibration) or scaled (parameterisation) intensity of the 3550 cm -1 band. A total of 67 mafic (basanite, basalt) and intermediate (andesite) glasses hosted in olivines, having between 0.2 and 4.8 wt% of H 2O, was analysed. Our new dataset demonstrates, for given water content, the height (intensity) of Raman H 2O T band depends on glass density, reflectance and water environment. Hence this matrix effect must be considered in the quantification of H 2O by Raman spectroscopy irrespective of the procedure, whereas the parameterisation mainly helps to predict and verify the self-consistency of the Raman results. In addition, to validate the capability of the micro-Raman to accurately determine the H 2O content of multicomponent aluminosilicate glasses, a subset of 23 glasses was analysed by both micro-Raman and micro-FTIR spectroscopy using the band at 3550 cm -1. We provide new FTIR absorptivity coefficients ( ɛ3550) for basalt (62.80 ± 0.8 L mol -1 cm -1) and basanite (43.96 ± 0.6 L mol -1 cm -1). These values, together with an exhaustive review of literature data, confirm the non-linear decline

  17. Are floating algal mats a refuge from hypoxia for estuarine invertebrates?

    PubMed Central

    Knysh, Kyle M.; Theriault, Emma F.; Pater, Christina C.; Courtenay, Simon C.; van den Heuvel, Michael R.

    2017-01-01

    Eutrophic aquatic habitats are characterized by the proliferation of vegetation leading to a large standing biomass that upon decomposition may create hypoxic (low-oxygen) conditions. This is indeed the case in nutrient impacted estuaries of Prince Edward Island, Canada, where macroalgae, from the genus Ulva, form submerged ephemeral mats. Hydrological forces and gases released from photosynthesis and decomposition lead to these mats occasionally floating to the water’s surface, henceforth termed floating mats. Here, we explore the hypothesis that floating mats are refugia during periods of sustained hypoxia/anoxia and examine how the invertebrate community responds to it. Floating mats were not always present, so in the first year (2013) sampling was attempted monthly and limited to when both floating and submerged mats occurred. In the subsequent year sampling was weekly, but at only one estuary due to logistical constraints from increased sampling frequency, and was not limited to when both mat types occurred. Water temperature, salinity, and pH were monitored bi-weekly with dissolved oxygen concentration measured hourly. The floating and submerged assemblages shared many of the same taxa but were statistically distinct communities; submerged mats tended to have a greater proportion of benthic animals and floating mats had more mobile invertebrates and insects. In 2014, sampling happened to occur in the weeks before the onset of anoxia, during 113 consecutive hours of sustained anoxia, and for four weeks after normoxic conditions returned. The invertebrate community on floating mats appeared to be unaffected by anoxia, indicating that these mats may be refugia during times of oxygen stress. Conversely, there was a dramatic decrease in animal abundances that remained depressed on submerged mats for two weeks. Cluster analysis revealed that the submerged mat communities from before the onset of anoxia and four weeks after anoxia were highly similar to each other

  18. The role of RAP1 in the regulation of the MAT alpha locus.

    PubMed Central

    Giesman, D; Best, L; Tatchell, K

    1991-01-01

    The RAP1 gene of Saccharomyces cerevisiae encodes an abundant DNA-binding protein, also known as GRF1, TBA, or TUF, that binds to many sites in the yeast genome in vitro. These sites define a consensus sequence, [sequence: see text], and deletion analyses of genes that contain this sequence have implicated the involvement of RAP1 in numerous cellular processes, including gene activation and repression. The MAT alpha locus, required for determination of the alpha cell type in yeast cells, contains a RAP1 binding site; this site coincides with the MAT alpha upstream activating sequence (UAS) and is necessary for expression of the two genes encoded by the MAT alpha locus, MAT alpha 1 and MAT alpha 2. We show that the MAT alpha UAS is sufficient to activate transcription from a promoterless gene fusion of the yeast CYC1 upstream region and the lacZ gene. Constructs containing only the MAT alpha UAS generated elevated levels of beta-galactosidase activity which were indistinguishable from those of constructs containing the entire MAT alpha intergenic region. Further, the MAT alpha UAS has an intrinsic polarity of transcriptional activation; transcription of CYC1-lacZ was six- to sevenfold higher when the UAS was oriented in the direction normally associated with MAT alpha 2 transcription. Point mutations in the MAT alpha UAS that reduce MAT alpha expression three- to fivefold resulted in a bi-mating phenotype, while a mutation that reduced MAT alpha expression still further resulted in an a-mating phenotype. We isolated plasmids from a high-copy-number yeast library that suppressed the bi-mating defect of point mutations in the MAT alpha UAS, and the most effective dosage suppressor contained the gene encoding RAP1. A temperature-sensitive rap1 mutant bi-mates at the semipermissive temperature. Double mutants at rap1 and mat alpha mate exclusively as a cells, at all temperatures, and do not express detectable levels of MAT alpha RNA. These data provide evidence that the

  19. Are floating algal mats a refuge from hypoxia for estuarine invertebrates?

    PubMed

    Coffin, Michael R S; Knysh, Kyle M; Theriault, Emma F; Pater, Christina C; Courtenay, Simon C; van den Heuvel, Michael R

    2017-01-01

    Eutrophic aquatic habitats are characterized by the proliferation of vegetation leading to a large standing biomass that upon decomposition may create hypoxic (low-oxygen) conditions. This is indeed the case in nutrient impacted estuaries of Prince Edward Island, Canada, where macroalgae, from the genus Ulva, form submerged ephemeral mats. Hydrological forces and gases released from photosynthesis and decomposition lead to these mats occasionally floating to the water's surface, henceforth termed floating mats. Here, we explore the hypothesis that floating mats are refugia during periods of sustained hypoxia/anoxia and examine how the invertebrate community responds to it. Floating mats were not always present, so in the first year (2013) sampling was attempted monthly and limited to when both floating and submerged mats occurred. In the subsequent year sampling was weekly, but at only one estuary due to logistical constraints from increased sampling frequency, and was not limited to when both mat types occurred. Water temperature, salinity, and pH were monitored bi-weekly with dissolved oxygen concentration measured hourly. The floating and submerged assemblages shared many of the same taxa but were statistically distinct communities; submerged mats tended to have a greater proportion of benthic animals and floating mats had more mobile invertebrates and insects. In 2014, sampling happened to occur in the weeks before the onset of anoxia, during 113 consecutive hours of sustained anoxia, and for four weeks after normoxic conditions returned. The invertebrate community on floating mats appeared to be unaffected by anoxia, indicating that these mats may be refugia during times of oxygen stress. Conversely, there was a dramatic decrease in animal abundances that remained depressed on submerged mats for two weeks. Cluster analysis revealed that the submerged mat communities from before the onset of anoxia and four weeks after anoxia were highly similar to each other

  20. Molecular Ecological and Stable Isotopic Studies of Nitrogen Fixation in Modern Microbial Mats

    NASA Technical Reports Server (NTRS)

    Bebout, B. M.; Crumbliss, L. L.; DesMarais, D. J.; Hogan, M. E.; Omoregie, E.; Turk, K. A.; Zehr, J. P.

    2003-01-01

    Nitrogen is usually the element limiting biological productivity in the marine environment. Microbial mats, laminated microbial communities analogous to some of the oldest forms of life on Earth, are often the sites of high rates of N fixation (the energetically expensive conversion of atmospheric dinitrogen into a biologically useful form). The N fixing enzyme nitrogenase is generally considered to be of ancient origin, and is widely distributed throughout the Bacterial and Archaeal domains of life, indicating an important role for this process over evolutionary time. The stable isotopic signature of N fixation is purportedly recognizable in organic matter (ancient kerogens as well as present-day microbial mats) as a delta (15)N(sub organic) near zero. We studied two microbial mats exhibiting different rates of N fixation in order to better understand the impact of N fixation on the delta (15)N (sub organic) of the mats, as well as what organisms are important in this process. Mats dominated by the cyanobacterium Microcoleus chthonoplastes grow in permanently submerged hypersaline salterns, and exhibit low rates of N fixation, whereas mats dominated by the cyanobacterium Lyngbya spp grow in an intertidal area, and exhibit rates of N fixation an order of magnitude higher. To examine successional stages in mat growth, both developing and established mats at each location were sampled. PCR and RT-PCR based approaches were used to identify, respectively, the organisms containing nifH (one of the genes that encode nitrogenase) as well as those expressing nifH in these mats. Both mats exhibited a distinct diel cycle of N fixation, with highest rates occurring at night. The delta (15)N(sub organic) of the subtidal Microcoleus mats is near zero whereas the delta (15)N(sub organic) is slightly more positive (+ 2-3%), in the intertidal Lyngbya mats, an interesting difference in view of the fact that overall rates of activity in the intertidal mats are much higher that those

  1. Drugstore Reading Glasses

    NASA Astrophysics Data System (ADS)

    Erlichson, Herman

    2006-03-01

    The occasion for this paper was my reading of a paper in the February 2005 issue of TPT. As one gets older the near point of the eye begins to recede.2 This is called presbyopia.3 An alternative to purchasing glasses from an optometrist is to purchase an inexpensive pair of reading glasses in a pharmacy. The pharmacy has these glasses ordered by diopters corresponding to the strength of the lens needed for a particular presbyopic eye. The glasses are, of course, not available for myopic eyes.

  2. Chalcogenide glass microsphere laser.

    PubMed

    Elliott, Gregor R; Murugan, G Senthil; Wilkinson, James S; Zervas, Michalis N; Hewak, Daniel W

    2010-12-06

    Laser action has been demonstrated in chalcogenide glass microsphere. A sub millimeter neodymium-doped gallium lanthanum sulphide glass sphere was pumped at 808 nm with a laser diode and single and multimode laser action demonstrated at wavelengths between 1075 and 1086 nm. The gallium lanthanum sulphide family of glass offer higher thermal stability compared to other chalcogenide glasses, and this, along with an optimized Q-factor for the microcavity allowed laser action to be achieved. When varying the pump power, changes in the output spectrum suggest nonlinear and/or thermal effects have a strong effect on laser action.

  3. Apollo 15 green glasses.

    NASA Technical Reports Server (NTRS)

    Ridley, W. I.; Reid, A. M.; Warner, J. L.; Brown, R. W.

    1973-01-01

    The samples analyzed include 28 spheres, portions of spheres, and angular fragments from soil 15101. Emerald green glasses from other soils are identical to those from 15101. The composition of the green glass is unlike that of any other major lunar glass group. The Fe content is comparable to that in mare basalts, but Ti is much lower. The Mg content is much higher than in most lunar materials analyzed to date, and the Cr content is also high. The low Al content is comparable to that of mare basalt glasses.

  4. Glass--Sand + Imagination

    NASA Astrophysics Data System (ADS)

    Kolb, Kenneth E.; Kolb, Doris K.

    2000-07-01

    Glass is older than recorded history, and yet it is as new as tomorrow! How, when, or where man first learned to make glass is not known, but we do know that the ancient Egyptians were making glass articles as early as 2,600 B.C.E. (The making of glass beads may have begun as much as 3000 years earlier.) They used it to make jewelry and luxury items, such as decorative bowls and perfume bottles, available only to the wealthy.

  5. Superhydrophobic silicone fiber mats fabricated by electrospinning from solution

    NASA Astrophysics Data System (ADS)

    Ludwig, Bonnie; Clark, Aneta; Snow, Steven; Hill, Randal; Schmidt, Randall; Fogg, Brad; Lo, Peter

    2007-03-01

    Fine silicone fibers of 1 -- 20 μm diameter were fabricated from solution via electrospinning. These are the first examples of fine fibers prepared from silicone homopolymers. Fiber morphology (beaded, ribbon-like, smooth) and diameter were controlled. The nanoscale surface roughness of nonwoven fiber mats created with silicone fibers produced a superhydrophobic surface that had a water contact angle of ˜160^o. The superhydrophobic surface was made reversibly hydrophilic with exposure to oxygen plasma. The combination of high surface area and superhydrophobicity suggests potential applications in the areas of water-repellent textiles, filtration, adsorption and chemical separations, wound dressings, and fuel cells.

  6. Electromagnetic scattering by pyramidal and wedge absorber

    NASA Technical Reports Server (NTRS)

    Dewitt, Brian T.; Burnside, Walter D.

    1988-01-01

    Electromagnetic scattering from pyramidal and wedge absorbers used to line the walls of modern anechoic chambers is measured and compared with theoretically predicted values. The theoretical performance for various angles of incidence is studied. It is shown that a pyramidal absorber scatters electromagnetic energy more as a random rough surface does. The apparent reflection coefficient from an absorber wall illuminated by a plane wave can be much less than the normal absorber specifications quoted by the manufacturer. For angles near grazing incidence, pyramidal absorbers give a large backscattered field from the pyramid side-faces or edges. The wedge absorber was found to give small backscattered fields for near-grazing incidence. Based on this study, some new guidelines for the design of anechoic chambers are advocated because the specular scattering models used at present do not appear valid for pyramids that are large compared to the wavelength.

  7. Magnetic field effects on microwave absorbing materials

    NASA Technical Reports Server (NTRS)

    Goldberg, Ira; Hollingsworth, Charles S.; Mckinney, Ted M.

    1991-01-01

    The objective of this program was to gather information to formulate a microwave absorber that can work in the presence of strong constant direct current (DC) magnetic fields. The program was conducted in four steps. The first step was to investigate the electrical and magnetic properties of magnetic and ferrite microwave absorbers in the presence of strong magnetic fields. This included both experimental measurements and a literature survey of properties that may be applicable to finding an appropriate absorbing material. The second step was to identify those material properties that will produce desirable absorptive properties in the presence of intense magnetic fields and determine the range of magnetic field in which the absorbers remain effective. The third step was to establish ferrite absorber designs that will produce low reflection and adequate absorption in the presence of intense inhomogeneous static magnetic fields. The fourth and final step was to prepare and test samples of such magnetic microwave absorbers if such designs seem practical.

  8. Experimental investigation of a nanofluid absorber employed in a low-profile, concentrated solar thermal collector

    NASA Astrophysics Data System (ADS)

    Li, Qiyuan; Zheng, Cheng; Mesgari, Sara; Hewakuruppu, Yasitha L.; Hjerrild, Natasha; Crisostomo, Felipe; Morrison, Karl; Woffenden, Albert; Rosengarten, Gary; Scott, Jason A.; Taylor, Robert A.

    2015-12-01

    Recent studies [1-3] have demonstrated that nanotechnology, in the form of nanoparticles suspended in water and organic liquids, can be employed to enhance solar collection via direct volumetric absorbers. However, current nanofluid solar collector experimental studies are either relevant to low-temperature flat plate solar collectors (<100 °C) [4] or higher temperature (>100 °C) indoor laboratory-scale concentrating solar collectors [1, 5]. Moreover, many of these studies involve in thermal properties of nanofluid (such as thermal conductivity) enhancement in solar collectors by using conventional selective coated steel/copper tube receivers [6], and no full-scale concentrating collector has been tested at outdoor condition by employing nanofluid absorber [2, 6]. Thus, there is a need of experimental researches to evaluate the exact performance of full-scale concentrating solar collector by employing nanofluids absorber at outdoor condition. As reported previously [7-9], a low profile (<10 cm height) solar thermal concentrating collector was designed and analysed which can potentially supply thermal energy in the 100-250 °C range (an application currently met by gas and electricity). The present study focuses on the design and experimental investigation of a nanofluid absorber employed in this newly designed collector. The nanofluid absorber consists of glass tubes used to contain chemically functionalized multi-walled carbon nanotubes (MWCNTs) dispersed in DI water. MWCNTs (average diameter of 6-13 nm and average length of 2.5-20 μm) were functionalized by potassium persulfate as an oxidant. The nanofluids were prepared with a MCWNT concentration of 50 +/- 0.1 mg/L to form a balance between solar absorption depth and viscosity (e.g. pumping power). Moreover, experimentally comparison of the thermal efficiency between two receivers (a black chrome-coated copper tube versus a MWCNT nanofluid contained within a glass tubetube) is investigated. Thermal

  9. Hydroxypropyl chitosan/organic rectorite-based nanofibrous mats with intercalated structure for bacterial inhibition.

    PubMed

    Deng, Hongbing; Lin, Penghua; Li, Wei; Xin, Shangjing; Zhou, Xue; Yang, Jianhong

    2013-01-01

    This paper reported antibacterial hydroxypropyl chitosan (HPCS)/organic rectorite (OREC)-based nanofibrous mats with intercalated structure fabricated via solution intercalation method and electrospinning. Field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, Energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and inhibition zone surrounding circular mats disks measurement were performed to characterize the morphology, intercalation structure, elements analysis, and the antibacterial properties of the as-spun nanofibrous mats. The results showed that the nanofibrous mats were with better fiber shape with the addition of OREC, the polymer chains were successfully intercalated into the interlayer of OREC, and nanofibrous mats containing HPCS exhibited good antibacterial activities against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus. In addition, the bacterial inhibition ability of the nanofibrous mats was enhanced when OREC was added.

  10. Hypersaline cyanobacterial mats as indicators of elevated tropical hurricane activity and associated climate change.

    PubMed

    Paerl, Hans W; Steppe, Timothy F; Buchan, Kenneth C; Potts, Malcolm

    2003-03-01

    The Atlantic hurricanes of 1999 caused widespread environmental damage throughout the Caribbean and US mid-Atlantic coastal regions. However, these storms also proved beneficial to certain microbial habitats; specifically, cyanobacteria-dominated mats. Modern mats represent the oldest known biological communities on earth, stromatolites. Contemporary mats are dominant biological communities in the hypersaline Bahamian lakes along the Atlantic hurricane track. We examined the impacts of varying levels of hypersalinity on 2 processes controlling mat growth, photosynthesis and nitrogen fixation, in Salt Pond, San Salvador Island, Bahamas. Hypersalinity (> 5 times seawater salinity) proved highly inhibitory to these processes. Freshwater input from Hurricane Floyd and other large storms alleviated this salt-inhibition. A predicted 10 to 40 year increase in Atlantic hurricane activity accompanied by more frequent "freshening" events will enhance mat productivity, CO2 sequestration and nutrient cycling. Cyanobacterial mats are sensitive short- and long-term indicators of climatic and ecological changes impacting these and other waterstressed environments.

  11. Enhancement of the in-plane shear properties of carbon fiber composites containing carbon nanotube mats

    NASA Astrophysics Data System (ADS)

    Kim, Hansang

    2015-01-01

    The in-plane shear property of carbon fiber laminates is one of the most important structural features of aerospace and marine structures. Fiber-matrix debonding caused by in-plane shear loading is the major failure mode of carbon fiber composites because of the stress concentration at the interfaces. In this study, carbon nanotube mats (CNT mat) were incorporated in two different types of carbon fiber composites. For the case of woven fabric composites, mechanical interlocking between the CNTs and the carbon fibers increased resistance to shear failure. However, not much improvement was observed for the prepreg composites as a result of incorporation of the CNT mats. The reinforcement mechanism of the CNT mat layer was investigated by a fractographic study using scanning electron microscopy. In addition, the CNT mat was functionalized by three different methods and the effectiveness of the functionalization methods was determined and the most appropriate functionalization method for the CNT mat was air oxidation.

  12. Electrospun magnetic nanofibre mats - A new bondable biomaterial using remotely activated magnetic heating

    NASA Astrophysics Data System (ADS)

    Zhong, Yi; Leung, Victor; Yuqin Wan, Lynn; Dutz, Silvio; Ko, Frank K.; Häfeli, Urs O.

    2015-04-01

    A solvothermal process was adopted to produce hydrophilic magnetite (Fe3O4) nanoparticles which were subsequently emulsified with a chloroform/methanol (70/30 v/v) solution of poly(caprolactone) (PCL) and then electrospun into a 0.2 mm thick PCL mat. The magnetic heating of the mats at a field amplitude of 25 kA/m and frequency of 400 kHz exhibited promising efficiency for magnetic hyperthermia, with a specific absorption rate of about 40 W/g for the magnetic mat. The produced heat was used to melt the magnetic mat onto the surrounding non-magnetic polymer mat from within, without destroying the nanostructure of the non-magnetic polymer more than 0.5 mm away. Magnetic nanofibre mats might thus be useful for internal heat sealing applications, and potentially also for thermotherapy.

  13. Preparation of Cu2ZnSnSe4 Absorber Layer by Nonvacuum Method

    NASA Astrophysics Data System (ADS)

    Liu, Shang-En; Lin, Yu-Hsuan; Huang, Hou-Ying

    2013-12-01

    Cu2ZnSnSe4 (CZTSe) was prepared by a nonvacuum, solution-based method, and used as an absorber layer in CZTSe solar cells. Copper(II) acetate monohydrate, zinc(II) acetate dehydrate, and tin(II) chloride dihydrate were used as the starting materials of the sol-gel method, and 2-methoxyethanol and monoethanolamine were used as the solvent and stabilizer, respectively. The precursor solution was deposited on Mo-coated soda lime glass (SLG) by spin-coating, then annealed at 570 °C in selenium atmosphere to convert it into the CZTSe absorber layer. The synthesized CZTSe absorber layer phase was identified by X-ray diffraction (XRD) and Raman spectrum analyses. By increasing the number of spin-coating/drying cycles, the CZTSe absorber layer thickness was increased and resulted in a current density increase in the current-voltage curve. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were carried out to confirm the absorber layer thickness and metal ratios. The highest efficiency of the solar cell was 1.08% with a 1.45 µm absorber layer.

  14. Numerical Investigation on Trapezoidal Cavity Receiver Used In LFR with Water Flow in Absorber Tubes

    NASA Astrophysics Data System (ADS)

    Duggal, Rohit; Jilte, Ravindra

    2017-03-01

    In the present study, numerical three dimensional model of trapezoidal cavity used in LFR was analysed. Results are presented in the form of Thermal losses occurring from the receiver operating with an absorber tube temperature from 350-550 K in step of 50 K and emissivity varied from 0.5-1.0. Effect of wind blowing below lower glass plate (cavity aperture) were also analysed considering the heat transfer coefficient from 5 to 25 W/m2K. At lower absorber temperature (350 K) convective losses is found to be 43% of the total heat loss whereas radiative losses accounted 57%. For higher absorber temperature radiative losses are dominant (77%) and convective losses are reduced to 23%. The air temperature gradient in the horizontal direction (parallel to lower glass plate) is found to be negligible whereas it is varied significantly in vertical direction (normal to lower glass plate). The average cavity air temperature is observed to be 480 K for low wind flow (h=5 W/m2K) and it reduces to 360 K for h=25 W/m2K. This has resulted in increased convective losses (27% higher).

  15. Absorbent product and articles made therefrom

    NASA Technical Reports Server (NTRS)

    Dawn, F. S.; Correale, J. V. (Inventor)

    1982-01-01

    A multilayer absorbent product for use in contact with the skin to absorb fluids is described. The product has a water pervious facing layer for contacting the skin, and a first fibrous wicking layer overlaying the water pervious layer. A first container section is defined by inner and outer layers of a water pervious wicking material in between a first absorbent mass and a second container section defined by inner and outer layers of a water pervious wicking material between what is disposed a second absorbent mass, and a liquid impermeable/gas permeable layer overlaying the second fibrous wicking layer.

  16. Nonlinear dynamic vibration absorbers with a saturation

    NASA Astrophysics Data System (ADS)

    Febbo, M.; Machado, S. P.

    2013-03-01

    The behavior of a new type of nonlinear dynamic vibration absorber is studied. A distinctive characteristic of the proposed absorber is the impossibility to extend the system to infinity. The mathematical formulation is based on a finite extensibility nonlinear elastic potential to model the saturable nonlinearity. The absorber is attached to a single degree-of-freedom linear/nonlinear oscillator subjected to a periodic external excitation. In order to solve the equations of motion and to analyze the frequency-response curves, the method of averaging is used. The performance of the FENE absorber is evaluated considering a variation of the nonlinearity of the primary system, the damping and the linearized frequency of the absorber and the mass ratio. The numerical results show that the proposed absorber has a very good efficiency when the nonlinearity of the primary system increases. When compared with a cubic nonlinear absorber, for a large nonlinearity of the primary system, the FENE absorber shows a better effectiveness for the whole studied frequency range. A complete absence of quasi-periodic oscillations is also found for an appropriate selection of the parameters of the absorber. Finally, direct integrations of the equations of motion are performed to verify the accuracy of the proposed method.

  17. Metamaterial absorber with random dendritic cells

    NASA Astrophysics Data System (ADS)

    Zhu, Weiren; Zhao, Xiaopeng

    2010-05-01

    The metamaterial absorber composed of random dendritic cells has been investigated at microwave frequencies. It is found that the absorptivities come to be weaker and the resonant frequency get red shift as the disordered states increasing, however, the random metamaterial absorber still presents high absorptivity more than 95%. The disordered structures can help understanding of the metamaterial absorber and may be employed for practical design of infrared metamaterial absorber, which may play important roles in collection of radiative heat energy and directional transfer enhancement.

  18. Characterization of arsenic species in microbial mats from an inactive gold mine

    USGS Publications Warehouse

    Foster, A.L.; Ashley, R.P.

    2002-01-01

    Filamentous cyanobacterial mats and Fe oxyhydroxide-rich bacterial mats collected near an inactive gold mine in California are enriched in arsenic (As) approximately 1000-fold relative to the waters in contact with them. The predominant organism in the cyanobacterial mat could not be identified using morphological characteristics, but the unique morphology of the sheath-forming ?? protobacterium Leptothrix ochracea was used to identify this species in Fe oxyhydroxide mat samples from several sites near the gold mine. Leptothrix sheaths commonly exceed 10 ??m in length and have an average diameter of 1 ??m. The Fe-oxyhydroxide mats are dominated by L. ochracea sheaths, but use of fluorescently tagged genetic stains reveals the presence of sheathless bacteria that presumably also promote the formation of Fe oxyhydroxide. X-ray absorption fine structure (XAFS) spectroscopy was used to identify As species in these microbial mats. Mat-associated As is predominantly As(V), even when As(III) is the primary dissolved species in contact with the mats. The species of As(V) associated with the cyanobacterial mat could not be conclusively identified; however, it is not associated with Fe oxyhydroxide or other minerals, based on comparison to XAFS spectra of As adsorbed to various substrates. In addition, the cyanobacterial mat XAFS spectrum is different from that of aqueous As(V), suggesting that As(V) in the mat lacks some or all of the coordinating water molecules present in aqueous solution. We hypothesize that As is associated with the exopolysaccharide (EPS) matrix secreted by the cyanobacteria. In Leptothrix-dominated Fe-oxyhydroxide bacterial mats, XAFS analysis clearly indicates that As(V) is associated with the Fe oxyhydroxide as an adsorbed and/or coprecipitated complex.

  19. MILLIMETER-SCALE GENETIC GRADIENTS AND COMMUNITY-LEVEL MOLECULAR CONVERGENCE IN A HYPERSALINE MICROBIAL MAT

    SciTech Connect

    Fenner, Marsha W; Kunin, Victor; Raes, Jeroen; Harris, J. Kirk; Spear, John R.; Walker, Jeffrey J.; Ivanova, Natalia; Mering, Christian von; Bebout, Brad M.; Pace, Norman R.; Bork, Peer; Hugenholtz, Philip

    2008-04-30

    To investigate the extent of genetic stratification in structured microbial communities, we compared the metagenomes of 10 successive layers of a phylogenetically complex hypersaline mat from Guerrero Negro, Mexico. We found pronounced millimeter-scale genetic gradients that are consistent with the physicochemical profile of the mat. Despite these gradients, all layers displayed near identical and acid-shifted isoelectric point profiles due to a molecular convergence of amino acid usage indicating that hypersalinity enforces an overriding selective pressure on the mat community.

  20. Determination of Fe(II)Fe(II) ratio in glass

    SciTech Connect

    Baumann, E.W.

    1989-07-26

    The procedure was designed for the simple, rapid determination of the Fe(II)/Fe(III) ratio in glass samples. The procedure consists of the following steps: dissolution of the pulverized glass sample in a sulfuric-hydrofluoric acid mixture, containing ammonium vanadate, which preserves the Fe(II) content; addition of boric acid to destroy iron-fluoride complexes, making the iron available for color formation with Ferrozine; addition of pH 5 buffer and Ferrozine reagent to form the magenta-colored ferrous-Ferrozine complex, with measurement of the absorbance for the determination of Fe(II) content; and, addition of ascorbic acid to reduce Fe(III) to Fe(II), with a second absorbance measurement that determines total Fe. Directions for the preparation of glass from non-radioactive sludge samples are provided. The analysis of this prepared glass for the Fe(II)/Fe(III) ratio is an indication of the ratio that would be in a plant batch of glass if made from this sludge.

  1. Coastal Microbial Mat Diversity along a Natural Salinity Gradient

    PubMed Central

    Bolhuis, Henk; Fillinger, Lucas; Stal, Lucas J.

    2013-01-01

    The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae. PMID:23704895

  2. Coastal microbial mat diversity along a natural salinity gradient.

    PubMed

    Bolhuis, Henk; Fillinger, Lucas; Stal, Lucas J

    2013-01-01

    The North Sea coast of the Dutch barrier island of Schiermonnikoog is covered by microbial mats that initiate a succession of plant communities that eventually results in the development of a densely vegetated salt marsh. The North Sea beach has a natural elevation running from the low water mark to the dunes resulting in gradients of environmental factors perpendicular to the beach. These gradients are due to the input of seawater at the low water mark and of freshwater from upwelling groundwater at the dunes and rainfall. The result is a natural and dynamic salinity gradient depending on the tide, rainfall and wind. We studied the microbial community composition in thirty three samples taken every ten meters along this natural salinity gradient by using denaturing gradient gel electrophoresis (DGGE) of rRNA gene fragments. We looked at representatives from each Domain of life (Bacteria, Archaea and Eukarya) and with a particular emphasis on Cyanobacteria. Analysis of the DGGE fingerprints together with pigment composition revealed three distinct microbial mat communities, a marine community dominated by diatoms as primary producers, an intermediate brackish community dominated by Cyanobacteria as primary producers and a freshwater community with Cyanobacteria and freshwater green algae.

  3. Single cell visualization of sulfur cycling in intertidal microbial mats

    NASA Astrophysics Data System (ADS)

    Dawson, K.; Green, A.; Orphan, V. J.

    2014-12-01

    Chemoautrophic microbial mats form in shallow intertidal pools adjacent to sulfidic hydrothermal vents in San Pedro, CA. Sulfide is primarily geologically derived. However, microscopy revealed deltaproteobacteria closely associated with Beggiatoa -like filaments, indicating an additional biogenic sulfide source, derived from sulfate reduction or sulfur disproportionation. At small scales the intercellular interaction of sulfide producing and sulfide consuming bacteria may play a important role in biogeochemical sulfur cycling. We explored the intracellular transfer of biologically derived sulfide in this system with triple and quadruple stable isotope labeling experiments: 13C, 15N, 33S, and 34S. Silicon wafers colonized by microbial mats in situ, were then incubated with 34SO42- or 34SO42- and 33S0 as well as 13C-acetate and 15NH4+and analyzed by fluorescent in situ hybridization (FISH) coupled to nanometer-scale secondary ion mass spectrometry (NanoSIMS). We observed enrichment of 34S and 33S in both deltaproteobacteria and sulfide oxidizing gammaproteobacteria. Greater enrichment relative to killed controls occurred in deltaproteobacteria than the sulfide oxidizers during both sulfate reducing (Δ34Sdelta-killed = 240‰, Δ34Sgamma-killed = 40‰) and sulfur disproportionating incubations (Δ33Sdelta-killed = 1730‰, Δ33Sgamma-killed = 1050‰). These results provide a direct visualization of interspecies sulfur transfer and indicate that biogenic sulfide derived from either sulfate or intermediate oxidation state sulfur species plays a role in sulfur cycling in this system.

  4. Deformed microbial mat structures in a semiarid temperate coastal setting

    NASA Astrophysics Data System (ADS)

    Cuadrado, Diana G.; Pan, Jerónimo; Gómez, Eduardo A.; Maisano, Lucía

    2015-07-01

    This study focuses on sedimentary structures formed by microbial consortia, in a particular coastal setting, an ancient tidal channel, separated from the ocean by a sandy spit and connected by a blind tidal channel at the opposite end. Most studies in modern and ancient environments consider water movement as the triggering mechanism acting in the formation and deformation of sedimentary structures. As such, the paper documents the presence of several microbial structures such as shrinkage cracks, flip-over mats, microbial chips, and multidirectional ripples which are related to tidal processes, while bulges and gas domes structures are formed after occasional inundation events. However, the more conspicuous structures covering a great area at the study site are folds and roll-ups, the product of deformation of microbially induced structures by the action of sporadic spring-tidal currents due to strong winds. Therefore, the objective of this research is to document modern sedimentary structures in a coastal area and to provide a mechanistic explanation for their formation, based on the interplaying effects of the moisture variation and high shear stress. Also, several microbial sedimentary structures are distinguished throughout vertical sediment cores, such as microbial chips, detached mat, sponge fabrics, tears, and concentric structures, which are identified in a sedimentary profile. Through the recognition and interpretation of modern sedimentary deformation structures, this study contributes empirical tools for the reconstruction of analogous paleoenvironments in fossil studies.

  5. Role of Polyphosphate in Thermophilic Synechococcus sp. from Microbial Mats

    PubMed Central

    Fazeli, Fariba; Grote, Alexandra; Grossman, Arthur R.; Bhaya, Devaki

    2013-01-01

    Synechococcus OS-B′, a thermophilic unicellular cyanobacterium, recently isolated from the microbial mats in Octopus Spring (Yellowstone National Park), induces a suite of genes, including phosphatases and transporters, in response to phosphorus (P) starvation. Here we describe two different approaches to examine the ability of Synechococcus OS-B′ to synthesize and break down polyphosphate (poly P), a key storage compound in many prokaryotes. First, we developed a transformation protocol to create mutants in the polyphosphate kinase (ppk), the major enzyme responsible for the synthesis of poly P. The ppk mutant exhibited a pleiotropic phenotype with defects in poly P accumulation, aberrant levels of Pho regulon transcripts, growth defects, and changes in cell size and exopolysaccharide levels, among others. Second, we measured transcripts of ppk and ppx (encoding the polyphosphatase) directly from mat samples and found that the levels varied dramatically over a diel cycle. We also used Western blot analysis to quantify levels of PPK and PPX and found that these enzymes differentially accumulated during the diel cycle. Levels of polyphosphate kinase peaked at night, while polyphosphatase levels were highest during the early morning hours. We hypothesize that the opposing activities of these two enzymes allow cells to store and utilize poly P to optimize growth over a diel cycle. PMID:23687278

  6. Lipid Biomarkers for a Hypersaline Microbial Mat Community

    NASA Technical Reports Server (NTRS)

    Jahnke, Linda L.; Embaye, Tsege; Turk, Kendra A.

    2003-01-01

    The use of lipid biomarkers and their carbon isotopic compositions are valuable tools for establishing links to ancient microbial ecosystems. As witnessed by the stromatolite record, benthic microbial mats grew in shallow water lagoonal environments where microorganisms had virtually no competition apart from the harsh conditions of hypersalinity, desiccation and intense light. Today, the modern counterparts of these microbial ecosystems find appropriate niches in only a few places where extremes eliminate eukaryotic grazers. Answers to many outstanding questions about the evolution of microorganisms and their environments on early Earth are best answered through study of these extant analogs. Lipids associated with various groups of bacteria can be valuable biomarkers for identification of specific groups of microorganisms both in ancient organic-rich sedimentary rocks (geolipids) and contemporary microbial communities (membrane lipids). Use of compound specific isotope analysis adds additional refinement to the identification of biomarker source, so that it is possible to take advantage of the 3C-depletions associated with various functional groups of organisms (i.e. autotrophs, heterotrophs, methanotrophs, methanogens) responsible for the cycling of carbon within a microbial community. Our recent work has focused on a set of hypersaline evaporation ponds at Guerrero Negro, Baja California Sur, Mexico which support the abundant growth of Microcoleus-dominated microbial mats. Specific biomarkers for diatoms, cyanobacteria, archaea, green nonsulfur (GNS), sulfate reducing, and methanotrophic bacteria have been identified. Analyses of the ester-bound fatty acids indicate a highly diverse microbial community, dominated by photosynthetic organisms at the surface.

  7. Evaluation of thermally crosslinkable chitosan-based nanofibrous mats for the removal of metal ions.

    PubMed

    Huang, Chih-Hao; Hsieh, Te-Hsien; Chiu, Wen-Yen

    2015-02-13

    Environmentally sensitive composite nanofibrous mats capable of metal ion adsorption were successfully prepared via electrospinning. The composite nanofibers were fabricated with different ratios of chitosan to thermo-responsive polymer, poly(N-isopropylacrylamide-co-N-methylolacrylamide) (poly(NIPAAm-co-NMA), PNN). NMA provided the function of thermal crosslinking of the nanofibrous mats to form water-stable nanofibers in aqueous solution. Subsequently, glutaraldehyde was used as a secondary crosslinking agent to increase the gel fraction of the nanofibrous mats. The morphology changes of the nanofibers in different environments were studied. Comparing the nanofibrous mats and films of the same material, the fibrous mats showed significantly increased adsorption of Cu(II). The adsorption amount of Cu(II) on the chitosan/PNN (50/50) nanofibrous mats could reach 79±2 mg/g-mats, and its desorption was relatively effective. The incorporation of poly(NIPAAm-co-NMA) significantly improved the desorption of Cu(II) from the nanofibrous mats. The chitosan/PNN fibrous mats maintained the capacity of Cu(II) adsorption for 4-time regeneration.

  8. New crosslinkers for electrospun chitosan fibre mats. Part II: mechanical properties

    PubMed Central

    Donius, Amalie E.; Kiechel, Marjorie A.; Schauer, Caroline L.; Wegst, Ulrike G. K.

    2013-01-01

    Few studies exist on the mechanical performance of crosslinked electrospun chitosan (CS) fibre mats. In this study, we show that the mat structure and mechanical performance depend on the different crosslinking agents genipin, epichlorohydrin (ECH), and hexamethylene-1,6-diaminocarboxysulphonate (HDACS), as well as the post-electrospinning heat and base activation treatments. The mat structure was imaged by field emission scanning electron microscopy and the mechanical performance was tested in tension. The elastic modulus, tensile strength, strain at failure and work to failure were found to range from 52 to 592 MPa, 2 to 30 MPa, 2 to 31 per cent and 0.041 to 3.26 MJ m−3, respectively. In general, neat CS mats were found to be the stiffest and the strongest, though least ductile, while CS–ECH mats were the least stiff, weakest, but the most ductile, and CS–HDACS fibre mats exhibited intermediary mechanical properties. The mechanical performance of the mats is shown to reflect differences in the fibre diameter, number of fibre–fibre contacts formed within the mat, as well as varying intermolecular bonding and moisture content. The findings reported here complement the chemical properties of the mats, described in part I of this study. PMID:23349435

  9. New crosslinkers for electrospun chitosan fibre mats. Part II: mechanical properties.

    PubMed

    Donius, Amalie E; Kiechel, Marjorie A; Schauer, Caroline L; Wegst, Ulrike G K

    2013-04-06

    Few studies exist on the mechanical performance of crosslinked electrospun chitosan (CS) fibre mats. In this study, we show that the mat structure and mechanical performance depend on the different crosslinking agents genipin, epichlorohydrin (ECH), and hexamethylene-1,6-diaminocarboxysulphonate (HDACS), as well as the post-electrospinning heat and base activation treatments. The mat structure was imaged by field emission scanning electron microscopy and the mechanical performance was tested in tension. The elastic modulus, tensile strength, strain at failure and work to failure were found to range from 52 to 592 MPa, 2 to 30 MPa, 2 to 31 per cent and 0.041 to 3.26 MJ m(-3), respectively. In general, neat CS mats were found to be the stiffest and the strongest, though least ductile, while CS-ECH mats were the least stiff, weakest, but the most ductile, and CS-HDACS fibre mats exhibited intermediary mechanical properties. The mechanical performance of the mats is shown to reflect differences in the fibre diameter, number of fibre-fibre contacts formed within the mat, as well as varying intermolecular bonding and moisture content. The findings reported here complement the chemical properties of the mats, described in part I of this study.

  10. The role of simulation in the development and flight test of the HiMAT vehicle

    NASA Technical Reports Server (NTRS)

    Evans, M. B.; Schilling, L. J.

    1984-01-01

    Real time simulations have been essential in the flight test program of the highly maneuverable aircraft technology (HiMAT) remotely piloted research vehicle at NASA Ames Research Center's Dryden Flight Research Facility. The HiMAT project makes extensive use of simulations in design, development, and qualification for flight, pilot training, and flight planning. Four distinct simulations, each with varying amounts of hardware in the loop, were developed for the HiMAT project. The use of simulations in detecting anomalous behavior of the flight software and hardware at the various stages of development, verification, and validation has been the key to flight qualification of the HiMAT vehicle.

  11. Aligned Electrospun Polyvinyl Pyrrolidone/Poly ɛ-Caprolactone Blend Nanofiber Mats for Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2016-02-01

    Electrospun nanofibrous materials are widely used in medical applications such as tissue engineering scaffolds, wound dressing material and drug delivery carriers. For tissue engineering scaffolds, the structure of the nanofiber is similar to extracellular matrix (ECM) which promotes the cell growth and proliferation. In the present study, the aligned nanofiber mats of polyvinyl pyrrolidone (PVP) blended poly ɛ-caprolactone (PCL) was successfully generated using electrospinning technique. The morphology of PVP/PCL nanofiber mats were characterized by scanning electron microspore (SEM). The chemical and crystalline structure of PVP/PCL nanofiber mats were analyzed using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffactometer (PXRD). The water contact angle of mats was investigated. Cell culture studies using normal human fibroblasts (NHF) were performed to assess cell morphology, cell alignment and cell proliferation. The results indicated that the fiber were in nanometer range. The PVP/PCL was well dispersed in nanofiber mats and was in amorphous form. The water contact angle of PVP/PCL nanofiber mats was lower than PCL nanofiber mats. The PVP/PCL nanofiber mats exhibited good biocompatibility with NHF cells. In summary, the PVP/PCL nanofiber mats had potential to be used in tissue engineering and regenerative medicine.

  12. Rare Earth Phosphate Glass and Glass-Ceramic Proton Conductors

    SciTech Connect

    De Jonghe, Lutgard C.; Ray, Hannah L.; Wang, Ruigang

    2008-12-03

    The structure and conductivity of cerium and lanthanum phosphate glasses and glass-ceramics were investigated. The effects of varying the metal to phosphate ratio in the glasses, doping LaP3O9 glasses with Ce, and recrystallization of CeP3O9 glasses, on the glasses' microstructure and total conductivity were investigated using XRD, SEM, and AC impedance techniques. Strong increases in conductivity occurred when the glasses were recrystallized: the conductivity of a cerium metaphosphate glass increased conductivity after recrystallization from 10-7.5 S/cm to 10-6 S/cm at 400oC.

  13. Lanthanoides in Glass and Glass Ceramics

    NASA Astrophysics Data System (ADS)

    Meinhardt, Jürgen; Kilo, Martin; Somorowsky, Ferdinand; Hopp, Werner

    2017-03-01

    Many types of glass contain lanthanoides; among them, special glass for optical applications is the one with the highest content of lanthanoides. The precise determination of the lanthanoides' concentration is performed by inductively coupled plasma-optical emission spectrometry (ICP-OES). However, up to now, there are no established standard processes guaranteeing a uniform approach to the lanthanoide analysis. The knowledge of the lanthanoides' concentrations is necessary on the microscale in some cases, especially if a suitable separation and recycling procedure is to be applied. Here, the analysis is performed by energy-dispersive X-ray (EDX) or wavelength-dispersive X-ray (WDX) analytics in the scanning electron microscope.

  14. Device for absorbing mechanical shock

    DOEpatents

    Newlon, C.E.

    1979-08-29

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  15. Device for absorbing mechanical shock

    DOEpatents

    Newlon, Charles E.

    1980-01-01

    This invention is a comparatively inexpensive but efficient shock-absorbing device having special application to the protection of shipping and storage cylinders. In a typical application, two of the devices are strapped to a cylinder to serve as saddle-type supports for the cylinder during storage and to protect the cylinder in the event it is dropped during lifting or lowering operations. In its preferred form, the invention includes a hardwood plank whose grain runs in the longitudinal direction. The basal portion of the plank is of solid cross-section, whereas the upper face of the plank is cut away to form a concave surface fittable against the sidewall of a storage cylinder. The concave surface is divided into a series of segments by transversely extending, throughgoing relief slots. A layer of elastomeric material is positioned on the concave face, the elastomer being extrudable into slots when pressed against the segments by a preselected pressure characteristic of a high-energy impact. The compressive, tensile, and shear properties of the hardwood and the elastomer are utilized in combination to provide a surprisingly high energy-absorption capability.

  16. Stability of noxythiolin solutions stored in plastic and glass containers.

    PubMed

    McCafferty, D F; Furness, K; Anderson, L

    1984-09-01

    The stability of two different concentrations (1% and 2.5% w/v) of noxythiolin (Noxyflex and Noxyflex S) stored at a variety of temperatures (4, 20 and 37 degrees C) in both plastic and glass bottles has been examined over a period of 40 days. During this period noxythiolin solutions held at 20 degrees and 37 degrees C attained equilibrium (K = 0.285 +/- 0.015 mol/l). Neither noxythiolin nor its degradation products (N-methylthiourea and formaldehyde) were absorbed by the plastic (polypropylene) containers used. Therefore, noxythiolin solutions can be stored in certain plastic (polypropylene) containers under the same conditions as recommended for glass bottles.

  17. Thermally efficient melting and fuel reforming for glass making

    DOEpatents

    Chen, Michael S.; Painter, Corning F.; Pastore, Steven P.; Roth, Gary S.; Winchester, David C.

    1991-01-01

    An integrated process for utilizing waste heat from a glass making furnace. The hot off-gas from the furnace is initially partially cooled, then fed to a reformer. In the reformer, the partially cooled off-gas is further cooled against a hydrocarbon which is thus reformed into a synthesis gas, which is then fed into the glass making furnace as a fuel. The further cooled off-gas is then recycled back to absorb the heat from the hot off-gas to perform the initial cooling.

  18. Getting Started with Glass

    ERIC Educational Resources Information Center

    White, Heather

    2007-01-01

    The metamorphosis of glass when heated is a magical process to students, yet teachers are often reluctant to try it in class. The biggest challenge in working with glass in the classroom is to simplify procedures just enough to ensure student success while maintaining strict safety practices so no students are injured. Project concepts and safety…

  19. Glasses and Contact Lenses

    MedlinePlus

    ... about special eyewear you can wear on the field. With glasses, you'll also want to find out how to clean them properly. And it helps if you have a glasses case and put them in it when you're not wearing them. The last thing you want is to sit on your ...

  20. Glasses and Contact Lenses

    MedlinePlus

    ... dientes Video: Getting an X-ray Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A What's in this ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  1. Surface Conductive Glass.

    ERIC Educational Resources Information Center

    Tanaka, John; Suib, Steven L.

    1984-01-01

    Discusses the properties of surface-conducting glass and the chemical nature of surface-conducting stannic (tin) oxide. Also provides the procedures necessary for the preparation of surface-conducting stannic oxide films on glass substrates. The experiment is suitable for the advanced inorganic chemistry laboratory. (JN)

  2. Dramatic Stained Glass.

    ERIC Educational Resources Information Center

    Prater, Michael

    2002-01-01

    Describes an art project that is appropriate for students in fifth through twelfth grade in which they create Gothic-style stained-glass windows. Discusses how college students majoring in elementary education created stained-glass windows. Addresses how to adapt this lesson for younger students. (CMK)

  3. Indium fluoride glass fibers

    NASA Astrophysics Data System (ADS)

    Saad, Mohammed

    2012-03-01

    Fluoride glasses are the only material that transmit light from ultraviolet to mid-infrared and can be drawn into industrial optical fibers. The mechanical and optical properties of new indium fluoride glass fibers have been investigated. Multimode fiber 190 microns, has very high mechanical strength greater than 100 kpsi and optical loss as low as 45 dB/km between 2 and 4 microns. Unlike chalcogenide glass fibers, indium fluoride fiber has a wide transmission window from 0.3 to 5.5 microns without any absorption peak. Indium fluoride glass fibers are the technology of choice for all application requiring transmission up to 5 micron such as infrared contour measure (IRCM) and chemical sensing. Furthermore, Indium fluoride glasses have low phonon energy and can be heavily doped and co-doped whit rare-earth elements. Therefore they are very promising candidates for infrared fiber lasers.

  4. Absorbencies of six different rodent beddings: commercially advertised absorbencies are potentially misleading.

    PubMed

    Burn, C C; Mason, G J

    2005-01-01

    Moisture absorbency is one of the most important characteristics of rodent beddings for controlling bacterial growth and ammonia production. However, bedding manufacturers rarely provide information on the absorbencies of available materials, and even when they do, absorption values are usually expressed per unit mass of bedding. Since beddings are usually placed into cages to reach a required depth rather than a particular mass, their volumetric absorbencies are far more relevant. This study therefore compared the saline absorbencies of sawdust, aspen woodchips, two virgin loose pulp beddings (Alpha-Dri and Omega-Dri), reclaimed wood pulp (Tek-Fresh), and corncob, calculated both by volume and by mass. Absorbency per unit volume correlated positively with bedding density, while absorbency per unit mass correlated negatively. Therefore, the relative absorbencies of the beddings were almost completely reversed depending on how absorbency was calculated. By volume, corncob was the most absorbent bedding, absorbing about twice as much saline as Tek-Fresh, the least absorbent bedding. Conversely, when calculated by mass, Tek-Fresh appeared to absorb almost three times as much saline as the corncob. Thus, in practical terms the most absorbent bedding here was corncob, followed by the loose pulp beddings; and this is generally supported by their relatively low ammonia production as seen in previous studies. Many factors other than absorbency determine whether a material is suitable as a rodent bedding, and they are briefly mentioned here. However, manufacturers should provide details of bedding absorbencies in terms of volume, in order to help predict the relative absorbencies of the beddings in practical situations.

  5. Photoprotection by window glass, automobile glass, and sunglasses.

    PubMed

    Tuchinda, Chanisada; Srivannaboon, Sabong; Lim, Henry W

    2006-05-01

    In daily activity, much time is spent indoors and in vehicles. Although the adverse effect of ultraviolet (UV) radiation is now well recognized and active public education programs on photoprotection have been undertaken, the role of window glass in photoprotection has been rarely addressed. It has been known for some time that window glass filters out UVB and transmits UVA and visible light. Recent developments in the glass industry have resulted in glass that provides broad UV protection without the historically associated loss of visible light transmission. Factors affecting UV-protective properties of glass are glass type, glass color, interleave between glass, and glass coating. In this article, photoprotection by window glass, automobile glass, and sunglasses is reviewed.

  6. An ultrathin dual-band metamaterial absorber

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Duan, Junping; Zhang, Wendong; Wang, Wanjun; Zhang, Binzhen

    2016-10-01

    The design and preparation of an ultrathin dual-band metamaterial absorber whose resonant frequency located at radar wave (20 GHz-60 GHz) is presented in this paper. The absorber is composed of a 2-D periodic sandwich featured with two concentric annuluses. The influence on the absorber's performance produced by resonant cell's structure size and material parameters was numerically simulated and analyzed based on the standard full wave finite integration technology in CST. Laser ablation process was adopted to prepare the designed absorber on epoxy resin board coated with on double plane of copper with a thickness that is 1/30 and 1/50 of the resonant wavelength at a resonant frequency of 30.51 GHz and 48.15 GHz. The full width at half maximum (FWHM) reached 2.2 GHz and 2.35 GHz and the peak of the absorptance reached 99.977%. The ultrathin absorber is nearly omnidirectional for all polarizations. The test results of prepared sample testify the designed absorber's excellent absorbing performance forcefully. The absorber expands inspirations of radar stealth in military domain due to its flexible design, cost-effective and other outstanding properties.

  7. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  8. 21 CFR 872.6050 - Saliva absorber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Saliva absorber. 872.6050 Section 872.6050 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6050 Saliva absorber. (a) Identification. A...

  9. Defense HLW Glass Degradation Model

    SciTech Connect

    D. Strachan

    2004-10-20

    The purpose of this report is to document the development of a model for calculating the release rate for radionuclides and other key elements from high-level radioactive waste (HLW) glasses under exposure conditions relevant to the performance of the repository. Several glass compositions are planned for the repository, some of which have yet to be identified (i.e., glasses from Hanford and Idaho National Engineering and Environmental Laboratory). The mechanism for glass dissolution is the same for these glasses and the glasses yet to be developed for the disposal of DOE wastes. All of these glasses will be of a quality consistent with the glasses used to develop this report.

  10. [Absorbed doses in dental radiology].

    PubMed

    Bianchi, S D; Roccuzzo, M; Albrito, F; Ragona, R; Anglesio, S

    1996-01-01

    The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk.

  11. B-scan based acoustic source reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI).

    PubMed

    Mariappan, Leo; Li, Xu; He, Bin

    2011-03-01

    We present in this study, an acoustic source reconstruction method using focused transducer with B-mode imaging for magnetoacoustic tomography with magnetic induction (MAT-MI). MAT-MI is an imaging modality proposed for noninvasive conductivity imaging with high spatial resolution. In MAT-MI, acoustic sources are generated in a conductive object by placing it in a static and a time-varying magnetic field. The acoustic waves from these sources propagate in all directions and are collected with transducers placed around the object. The collected signal is then used to reconstruct the acoustic source distribution and to further estimate the electrical conductivity distribution of the object. A flat piston transducer acting as a point receiver has been used in earlier MAT-MI systems to collect acoustic signals. In this study, we propose to use B-mode scan scheme with a focused transducer that gives a signal gain in its focus region and improves the MAT-MI signal quality. A simulation protocol that can take into account different transducer designs and scan schemes for MAT-MI imaging is developed and used in our evaluation of different MAT-MI system designs. It is shown in our computer simulations that as compared to the earlier approach, the MAT-MI system using B-scan with a focused transducer allows MAT-MI imaging at a closer distance and has improved system sensitivity. In addition, the B-scan imaging technique allows reconstruction of the MAT-MI acoustic sources with a discrete number of scanning locations, which greatly increases the applicability of the MAT-MI approach, especially when a continuous acoustic window is not available in real clinical applications. We have also conducted phantom experiments to evaluate the proposed method, and the reconstructed image shows a good agreement with the target phantom.

  12. Yoga from the Mat up: How Words Alight on Bodies

    ERIC Educational Resources Information Center

    McIlwain, Doris; Sutton, John

    2014-01-01

    Yoga is a unique form of expert movement that promotes an increasingly subtle interpenetration of thought and movement. The mindful nature of its practice, even at expert levels, challenges the idea that thought and mind are inevitably disruptive to absorbed coping. Building on parallel phenomenological and ethnographic studies of skilful…

  13. Design of a nonlinear torsional vibration absorber

    NASA Astrophysics Data System (ADS)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  14. Effect of different glasses in glass bonded zeolite

    SciTech Connect

    Lewis, M.A.; Ackerman, J.P.; Verma, S.

    1995-05-01

    A mineral waste form has been developed for chloride waste salt generated during the pyrochemical treatment of spent nuclear fuel. The waste form consists of salt-occluded zeolite powders bound within a glass matrix. The zeolite contains the salt and immobilizes the fission products. The zeolite powders are hot pressed to form a mechanically stable, durable glass bonded zeolite. Further development of glass bonded zeolite as a waste form requires an understanding of the interaction between the glass and the zeolite. Properties of the glass that enhance binding and durability of the glass bonded zeolite need to be identified. Three types of glass, boroaluminosilicate, soda-lime silicate, and high silica glasses, have a range of properties and are now being investigated. Each glass was hot pressed by itself and with an equal amount of zeolite. MCC-1 leach tests were run on both. Soda-lime silicate and high silica glasses did not give a durable glass bonded zeolite. Boroaluminosilicate glasses rich in alkaline earths did bind the zeolite and gave a durable glass bonded zeolite. Scanning electron micrographs suggest that the boroaluminosilicate glasses wetted the zeolite powders better than the other glasses. Development of the glass bonded zeolite as a waste form for chloride waste salt is continuing.

  15. Investigation of Chemical Durability Mechanism in Fluoride Glasses

    DTIC Science & Technology

    1985-12-01

    ammonium bifluoride . 3 In general, therefore, it appears that in deionized water the leach rate of fluorozirconate glasses is contzolled by both the...fluorozirconates leach rapidly in water, their solution * pH becomes acidic quickly, a thick hydrated surface layer forms which absorbs a large amount of water...layer. 9. The pH drift of the solution into an acidic region during tbe leaching raises the solubility of zirconium fluoride, which accelerates the

  16. Glass electrolyte composition

    DOEpatents

    Kucera, Gene H.; Roche, Michael F.

    1985-01-01

    An ionically conductive glass is disclosed for use as electrolyte in a high temperature electrochemical cell, particularly a cell with sodium anode and sulfur cathode. The glass includes the constituents Na.sub.2 O, ZrO.sub.2, Al.sub.2 O.sub.3 and SiO.sub.2 in selected proportions to be a single phase solid solution substantially free of crystalline regions and undissolved constituents. Other advantageous properties are an ionic conductivity in excess of 2.times.10.sup.-3 (ohm-cm).sup.-1 at 300.degree. C. and a glass transition temperature in excess of 500.degree. C.

  17. Glass electrolyte composition

    DOEpatents

    Kucera, G.H.; Roche, M.F.

    1985-01-08

    An ionically conductive glass is disclosed for use as electrolyte in a high temperature electrochemical cell, particularly a cell with sodium anode and sulfur cathode. The glass includes the constituents Na/sub 2/O, ZrO/sub 2/, Al/sub 2/O/sub 3/ and SiO/sub 2/ in selected proportions to be a single phase solid solution substantially free of crystalline regions and undissolved constituents. Other advantageous properties are an ionic conductivity in excess of 2 x 10/sup -3/ (ohm-cm)/sup -1/ at 300/sup 0/C and a glass transition temperature in excess of 500/sup 0/C.

  18. IPM Analysis of the Final Mercury and Air Toxics Standards (MATS)

    EPA Pesticide Factsheets

    EPA used version 4.10_MATS of the Integrated Planning Model (IPM) to analyze the impact of the Mercury and Air Toxics Standards (MATS) rule on the U.S. electric power sector. Learn about the results and view links to documentation.

  19. Niche differentiation of bacterial communities at a millimeter scale in Shark Bay microbial mats

    PubMed Central

    Wong, Hon Lun; Smith, Daniela-Lee; Visscher, Pieter T.; Burns, Brendan P.

    2015-01-01

    Modern microbial mats can provide key insights into early Earth ecosystems, and Shark Bay, Australia, holds one of the best examples of these systems. Identifying the spatial distribution of microorganisms with mat depth facilitates a greater understanding of specific niches and potentially novel microbial interactions. High throughput sequencing coupled with elemental analyses and biogeochemical measurements of two distinct mat types (smooth and pustular) at a millimeter scale were undertaken in the present study. A total of 8,263,982 16S rRNA gene sequences were obtained, which were affiliated to 58 bacterial and candidate phyla. The surface of both mats were dominated by Cyanobacteria, accompanied with known or putative members of Alphaproteobacteria and Bacteroidetes. The deeper anoxic layers of smooth mats were dominated by Chloroflexi, while Alphaproteobacteria dominated the lower layers of pustular mats. In situ microelectrode measurements revealed smooth mats have a steeper profile of O2 and H2S concentrations, as well as higher oxygen production, consumption, and sulfate reduction rates. Specific elements (Mo, Mg, Mn, Fe, V, P) could be correlated with specific mat types and putative phylogenetic groups. Models are proposed for these systems suggesting putative surface anoxic niches, differential nitrogen fixing niches, and those coupled with methane metabolism. PMID:26499760

  20. MAT gene idiomorphs suggest a heterothallic sexual cycle in a predominantly asexual and important pine pathogen.

    PubMed

    Bihon, Wubetu; Wingfield, Michael J; Slippers, Bernard; Duong, Tuan A; Wingfield, Brenda D

    2014-01-01

    Diplodia pinea (=Sphaeropsis sapinea) is a well-known and economically important latent pathogen of Pinus spp. in many parts of the world. Despite intensive scrutiny, its sexual state has never been observed and the fungus has thus been considered exclusively asexual. It was, therefore, surprising that a recent population genetics study showed high genotypic diversity and random association of alleles in a number of populations, suggesting that the pathogen has a cryptic sexual stage. Using the genome sequence of two individual D. pinea isolates, we interrogated the structure of the MAT locus in this fungus. The results suggested that D. pinea is heterothallic (self-sterile) with complete and apparently functional copies of the MAT genes containing the α-1 and HMG domains present in different isolates. In addition to the MAT1-2-1 and MAT1-1-1 genes, we found a MAT1-1-4 gene in the MAT1-1 idiomorph and a novel MAT1-2-5 gene in the MAT1-2 idiomorph. Importantly, the frequencies of occurrence of both idiomorphs in populations examined were not significantly different from a 1:1 ratio, which would be expected in sexually reproducing populations. Although the sexual state has never been observed, the results strongly suggest that D. pinea has a cryptic, heterothallic sexual cycle.

  1. Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming.

    PubMed

    Boyd, Eric S; King, Susan; Tomberlin, Jeffery K; Nordstrom, D Kirk; Krabbenhoft, David P; Barkay, Tamar; Geesey, Gill G

    2009-04-01

    Microbial mats are a visible and abundant life form inhabiting the extreme environments in Yellowstone National Park (YNP), WY, USA. Little is known of their role in food webs that exist in the Park's geothermal habitats. Eukaryotic green algae associated with a phototrophic green/purple Zygogonium microbial mat community that inhabits low-temperature regions of acidic (pH approximately 3.0) thermal springs were found to serve as a food source for stratiomyid (Diptera: Stratiomyidae) larvae. Mercury in spring source water was taken up and concentrated by the mat biomass. Monomethylmercury compounds (MeHg(+)), while undetectable or near the detection limit (0.025 ng l(-1)) in the source water of the springs, was present at concentrations of 4-7 ng g(-1) dry weight of mat biomass. Detection of MeHg(+) in tracheal tissue of larvae grazing the mat suggests that MeHg(+) enters this geothermal food web through the phototrophic microbial mat community. The concentration of MeHg(+) was two to five times higher in larval tissue than mat biomass indicating MeHg(+) biomagnification occurred between primary producer and primary consumer trophic levels. The Zygogonium mat community and stratiomyid larvae may also play a role in the transfer of MeHg(+) to species in the food web whose range extends beyond a particular geothermal feature of YNP.

  2. Understanding Molecular Recognition of Promiscuity of Thermophilic Methionine Adenosyltransferase, sMAT from Sulfolobus solfataricus

    PubMed Central

    Wang, Fengbin; Singh, Shanteri; Zhang, Jianjun; Huber, Tyler D.; Helmich, Kate E.; Sunkara, Manjula; Hurley, Katherine A.; Goff, Randal D.; Bingman, Craig A.; Morris, Andrew J.; Thorson, Jon S.; Phillips, George N.

    2014-01-01

    Methionine adenosyltransferase (MAT) is a family of enzymes that utilizes ATP and methionine to produce S-adenosylmethionine (AdoMet), the most crucial methyl donor in the biological methylation of biomolecules and bioactive natural products. Here, we report that the MAT from Sulfolobus solfataricus (sMAT), an enzyme from a poorly explored class of the MAT family, has the ability to produce a range of differentially alkylated AdoMet analogs in the presence of non-native methionine analogs and ATP. To investigate the molecular basis for AdoMet analog production, we have crystallized the sMAT in the AdoMet bound, S-adenosylethionine (AdoMet) bound, and unbound forms. Notably, among these structures, the AdoEth-bound form offers the first MAT structure containing a non-native product and cumulatively, these structures add new structural insight into the MAT family and allow for detailed active site comparison with its homologs in E. coli and human. As a thermostable MAT structure from archaea, the structures herein also provide as a basis for future engineering to potentially broaden AdoMet analog production as reagents for methyltransferase-catalyzed ‘alkylrandomization’ and/or the study of methylation in the context of biological processes. PMID:24649856

  3. Testing the utility of matK and ITS DNA regions for discrimination of Allium species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular phylogenetic analysis of the genus Allium L. has been mainly based on the nucleotide sequences of ITS region. In 2009 matK and rbcL were accepted as a two-locus DNA barcode to classify plant species by the Consortium for the Barcode of Life (CBOL) Plant Working Group. MatK region has been ...

  4. Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats.

    PubMed

    Lakshminarayanan, Rajamani; Sridhar, Radhakrishnan; Loh, Xian Jun; Nandhakumar, Muruganantham; Barathi, Veluchamy Amutha; Kalaipriya, Madhaiyan; Kwan, Jia Lin; Liu, Shou Ping; Beuerman, Roger Wilmer; Ramakrishna, Seeram

    2014-01-01

    Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections.

  5. Using Talking Mats to Support Communication in Persons with Huntington's Disease

    ERIC Educational Resources Information Center

    Ferm, Ulrika; Sahlin, Anna; Sundin, Linda; Hartelius, Lena

    2010-01-01

    Background: Many individuals with Huntington's disease experience reduced functioning in cognition, language and communication. Talking Mats is a visually based low technological augmentative communication framework that supports communication in people with different cognitive and communicative disabilities. Aims: To evaluate Talking Mats as a…

  6. Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming

    USGS Publications Warehouse

    Boyd, E.S.; King, S.; Tomberlin, J.K.; Nordstrom, D.K.; Krabbenhoft, D.P.; Barkay, T.; Geesey, G.G.

    2009-01-01

    Summary Microbial mats are a visible and abundant life form inhabiting the extreme environments in Yellowstone National Park (YNP), WY, USA. Little is known of their role in food webs that exist in the Park's geothermal habitats. Eukaryotic green algae associated with a phototrophic green/purple Zygogonium microbial mat community that inhabits low-temperature regions of acidic (pH ??? 3.0) thermal springs were found to serve as a food source for stratiomyid (Diptera: Stratiomyidae) larvae. Mercury in spring source water was taken up and concentrated by the mat biomass. Monomethylmercury compounds (MeHg +), while undetectable or near the detection limit (0.025 ng l -1) in the source water of the springs, was present at concentrations of 4-7 ng g-1 dry weight of mat biomass. Detection of MeHg + in tracheal tissue of larvae grazing the mat suggests that MeHg+ enters this geothermal food web through the phototrophic microbial mat community. The concentration of MeHg+ was two to five times higher in larval tissue than mat biomass indicating MeHg+ biomagnification occurred between primary producer and primary consumer trophic levels. The Zygogonium mat community and stratiomyid larvae may also play a role in the transfer of MeHg+ to species in the food web whose range extends beyond a particular geothermal feature of YNP. ?? 2008 The Authors. Journal compilation ?? 2008 Society for Applied Microbiology and Blackwell Publishing Ltd.

  7. Interaction of gelatin with polyenes modulates antifungal activity and biocompatibility of electrospun fiber mats

    PubMed Central

    Lakshminarayanan, Rajamani; Sridhar, Radhakrishnan; Loh, Xian Jun; Nandhakumar, Muruganantham; Barathi, Veluchamy Amutha; Kalaipriya, Madhaiyan; Kwan, Jia Lin; Liu, Shou Ping; Beuerman, Roger Wilmer; Ramakrishna, Seeram

    2014-01-01

    Topical application of antifungals does not have predictable or well-controlled release characteristics and requires reapplication to achieve therapeutic local concentration in a reasonable time period. In this article, the efficacy of five different US Food and Drug Administration-approved antifungal-loaded (amphotericin B, natamycin, terbinafine, fluconazole, and itraconazole) electrospun gelatin fiber mats were compared. Morphological studies show that incorporation of polyenes resulted in a two-fold increase in fiber diameter and the mats inhibit the growth of yeasts and filamentous fungal pathogens. Terbinafine-loaded mats were effective against three filamentous fungal species. Among the two azole antifungals compared, the itraconazole-loaded mat was potent against Aspergillus strains. However, activity loss was observed for fluconazole-loaded mats against all of the test organisms. The polyene-loaded mats displayed rapid candidacidal activities as well. Biophysical and rheological measurements indicate strong interactions between polyene antifungals and gelatin matrix. As a result, the polyenes stabilized the triple helical conformation of gelatin and the presence of gelatin decreased the hemolytic activity of polyenes. The polyene-loaded fiber mats were noncytotoxic to primary human corneal and sclera fibroblasts. The reduction of toxicity with complete retention of activity of the polyene antifungal-loaded gelatin fiber mats can provide new opportunities in the management of superficial skin infections. PMID:24920895

  8. Niche differentiation of bacterial communities at a millimeter scale in Shark Bay microbial mats

    NASA Astrophysics Data System (ADS)

    Wong, Hon Lun; Smith, Daniela-Lee; Visscher, Pieter T.; Burns, Brendan P.

    2015-10-01

    Modern microbial mats can provide key insights into early Earth ecosystems, and Shark Bay, Australia, holds one of the best examples of these systems. Identifying the spatial distribution of microorganisms with mat depth facilitates a greater understanding of specific niches and potentially novel microbial interactions. High throughput sequencing coupled with elemental analyses and biogeochemical measurements of two distinct mat types (smooth and pustular) at a millimeter scale were undertaken in the present study. A total of 8,263,982 16S rRNA gene sequences were obtained, which were affiliated to 58 bacterial and candidate phyla. The surface of both mats were dominated by Cyanobacteria, accompanied with known or putative members of Alphaproteobacteria and Bacteroidetes. The deeper anoxic layers of smooth mats were dominated by Chloroflexi, while Alphaproteobacteria dominated the lower layers of pustular mats. In situ microelectrode measurements revealed smooth mats have a steeper profile of O2 and H2S concentrations, as well as higher oxygen production, consumption, and sulfate reduction rates. Specific elements (Mo, Mg, Mn, Fe, V, P) could be correlated with specific mat types and putative phylogenetic groups. Models are proposed for these systems suggesting putative surface anoxic niches, differential nitrogen fixing niches, and those coupled with methane metabolism.

  9. Microbial mat mineralization in Great Salt Lake (Utah, USA)

    NASA Astrophysics Data System (ADS)

    PACE, Aurélie; Bouton, Anthony; Bourillot, Raphaël; Vennin, Emmanuelle; Visscher, Pieter; Dupraz, Christophe; Thomazo, Christophe; Serge, Galaup; Sophie, Leleu; Anna, Kwasniewski; Léa, Pigot; Michel, Franceschi

    2015-04-01

    Great Salt Lake is located in the Basin and Range province of Utah (USA). Its average surface is 4480 Km2 and its maximum depth is of about 15m. It is a partly rainfed endorheic hypersaline lake (average salinity: 140g/L). Due to the high salinity, little or no grazing organisms are present, favoring the development of microbialites that cover the margin of the lake. This work aims to understand the products and processes of mineralization in recent and modern microbialites on the western margin of Antelope Island. The distribution of microbialites and their morphology has been studied along lakeshore to center transects, showing a contrasting spatial distribution in bay versus headland. Fossil microbialites show a great diversity of macro- and microfabrics, some microbialites being essentially built by microbial-mediated carbonate precipitation, while other show the predominance of trapping and binding processes. The nature and composition of the microbial carbonates have been determined through polarizing, cathodoluminescence, reflected fluorescence microscopy, X-Ray diffractometry and isotope geochemistry (δ 18O and δ13C) in order to investigate the preservation of environmental signals in microbialites. Petrophysics analysis such as permeability and porosimetry, have been done to observe the structure of the microbialite. Microprobe and silver foils method have been used respectively to characterize oxygen production and sulfate reduction in living microbial mats. Mineralization zones seem to coincide with sulfate reduction hotspots. This mineralization results in mixed clotted-laminated fabric at the macro- and microscale. Several analysis such as Cryo-SEM, environmental SEM and raman spectroscopy three phases of mineralization allowed us to distinguish three type of minerals inside the mat: (1) a Mg and Si-rich clay developing on the organic matrix; (2) an intracellular Al-rich clay. (3) aragonite clots replacing the organic matrixes and embedding bacteria

  10. Thin film absorber for a solar collector

    DOEpatents

    Wilhelm, William G.

    1985-01-01

    This invention pertains to energy absorbers for solar collectors, and more particularly to high performance thin film absorbers. The solar collectors comprising the absorber of this invention overcome several problems seen in current systems, such as excessive hardware, high cost and unreliability. In the preferred form, the apparatus features a substantially rigid planar frame with a thin film window bonded to one planar side of the frame. An absorber in accordance with the present invention is comprised of two thin film layers that are sealed perimetrically. In a preferred embodiment, thin film layers are formed from a metal/plastic laminate. The layers define a fluid-tight planar envelope of large surface area to volume through which a heat transfer fluid flows. The absorber is bonded to the other planar side of the frame. The thin film construction of the absorber assures substantially full envelope wetting and thus good efficiency. The window and absorber films stress the frame adding to the overall strength of the collector.

  11. The mob as tumor suppressor (mats1) gene is required for growth control in developing zebrafish embryos.

    PubMed

    Yuan, Yuan; Lin, Shuo; Zhu, Zuoyan; Zhang, Wenxia; Lai, Zhi-Chun

    2009-01-01

    The mob as tumor suppressor (mats) family genes are highly conserved in evolution. The Drosophila mats gene functions in the Hippo signaling pathway to control tissue growth by regulating cell proliferation and apoptosis. However, nothing is known about whether mats family genes are required for the normal development of vertebrates. Here we report that zebrafish has three mats family genes. Expression of mats1 is maternally activated and continues during embryogenesis. Through a morpholino-based knockdown approach, we found that mats1 is required for normal embryonic development. Reduction of mats1 function caused developmental delay, a phenotype similar to that of Drosophila mats homozygous mutants. Both cell proliferation and apoptosis were defective in mats1 morphant embryos. Moreover, mats1 morphant cells exhibited a growth advantage in chimeric embryos, similar to mats mutant cells in mosaic tissues in Drosophila. Therefore mats1 plays a critical role in regulating cell proliferation and apoptosis during early development in zebrafish, and the role of mats family genes in growth regulation is conserved in both invertebrates and vertebrates. This work shows that zebrafish can be a good model organism for further analysis of Hippo signaling pathway.

  12. Silica glasses with nanoparticles of copper compounds: spectroscopy properties and laser passive shutter application

    NASA Astrophysics Data System (ADS)

    Yumashev, Konstantin V.; Prokoshin, Pavel V.; Zolotovskaya, Svetlana A.; Gurin, Valerij S.; Alexeenko, Alexander A.

    2003-11-01

    Sol-gel glasses containing copper selenide nanoparticles and having absorption band at 1.1?2.2 ?m can be used as saturable absorber passive shutter for Q-switching and mode-locking of the solid-state lasers operating in the wavelength range of 1.0?1.5 ?m. The bleaching relaxation time of the glasses was measured to be 0.46?1.4 ns in dependence on copper selenide stoichiometry.

  13. Spatially-resolved stable isotope analysis of a hypersaline microbial mat

    NASA Astrophysics Data System (ADS)

    Moran, J.; Cory, A. B.; Lindemann, S. R.; Fredrickson, J. K.

    2012-12-01

    Hot Lake is a hypersaline, meromictic lake located in north-central Washington. High rates of evapotranspiration coupled with its location in an endorrheic basin contribute to the lake's high salinity. The predominant dissolved salt is magnesium sulfate; hypolimnion waters may seasonally exceed 2 M magnesium sulfate concentrations. In addition to extreme salinity, horizons within the lake seasonally exceed 50 °C, in part due to the enhanced light absorption by magnesium sulfate-saturated water. Despite extreme and highly variable seasonal conditions (salinity, temperature, photon flux), dense benthic microbial mats composed of cyanobacteria and bacterial heterotroph populations develop annually at the lake. These mats may exceed 5 mm in thickness and display stratification observable by eye associated with dominant bacterial phototrophic pigments. Typical mat stratification includes an orange surface layer followed by green and purple layers at increasing depth into the mat. Carbonates including aragonite and magnesite are observed within the mat and their formation is likely induced or influenced by microbial activities. While not exclusively limited to the green stratum in the mat, maximum carbonate content is within this layer. We are exploring the role Hot Lake's microbial mats play in carbon cycling within the system. Namely, we seek to understand the rates of carbon accumulation in the mat and associated sediments and the various forms this carbon takes (organic or inorganic species). We are assessing mat development, community composition, and carbon accumulation in pre-cleaned devices installed at the lake as they are colonized by native mat. We are using laser ablation isotope ratio mass spectrometry (LA-IRMS) to provide spatially-resolved stable isotope analysis of mat cross-sections. Currently, this technique permits isotope analysis at the 50 μm scale, and can provide multiple isotope analyses within the thickness of each major layer of the mat. We

  14. The Architecture of Iron Microbial Mats Reflects the Adaptation of Chemolithotrophic Iron Oxidation in Freshwater and Marine Environments

    PubMed Central

    Chan, Clara S.; McAllister, Sean M.; Leavitt, Anna H.; Glazer, Brian T.; Krepski, Sean T.; Emerson, David

    2016-01-01

    Microbes form mats with architectures that promote efficient metabolism within a particular physicochemical environment, thus studying mat structure helps us understand ecophysiology. Despite much research on chemolithotrophic Fe-oxidizing bacteria, Fe mat architecture has not been visualized because these delicate structures are easily disrupted. There are striking similarities between the biominerals that comprise freshwater and marine Fe mats, made by Beta- and Zetaproteobacteria, respectively. If these biominerals are assembled into mat structures with similar functional morphology, this would suggest that mat architecture is adapted to serve roles specific to Fe oxidation. To evaluate this, we combined light, confocal, and scanning electron microscopy of intact Fe microbial mats with experiments on sheath formation in culture, in order to understand mat developmental history and subsequently evaluate the connection between Fe oxidation and mat morphology. We sampled a freshwater sheath mat from Maine and marine stalk and sheath mats from Loihi Seamount hydrothermal vents, Hawaii. Mat morphology correlated to niche: stalks formed in steeper O2 gradients while sheaths were associated with low to undetectable O2 gradients. Fe-biomineralized filaments, twisted stalks or hollow sheaths, formed the highly porous framework of each mat. The mat-formers are keystone species, with nascent marine stalk-rich mats comprised of novel and uncommon Zetaproteobacteria. For all mats, filaments were locally highly parallel with similar morphologies, indicating that cells were synchronously tracking a chemical or physical cue. In the freshwater mat, cells inhabited sheath ends at the growing edge of the mat. Correspondingly, time lapse culture imaging showed that sheaths are made like stalks, with cells rapidly leaving behind an Fe oxide filament. The distinctive architecture common to all observed Fe mats appears to serve specific functions related to chemolithotrophic Fe

  15. MatLab Programming for Engineers Having No Formal Programming Knowledge

    NASA Technical Reports Server (NTRS)

    Shaykhian, Linda H.; Shaykhian, Gholam Ali

    2007-01-01

    MatLab is one of the most widely used very high level programming languages for Scientific and engineering computations. It is very user-friendly and needs practically no formal programming knowledge. Presented here are MatLab programming aspects and not just the MatLab commands for scientists and engineers who do not have formal programming training and also have no significant time to spare for learning programming to solve their real world problems. Specifically provided are programs for visualization. Also, stated are the current limitations of the MatLab, which possibly can be taken care of by Mathworks Inc. in a future version to make MatLab more versatile.

  16. Structural and functional conservation of fungal MatA and human SRY sex-determining proteins.

    PubMed

    Czaja, Wioletta; Miller, Karen Y; Skinner, Michael K; Miller, Bruce L

    2014-11-17

    Sex determination in animals and fungi is regulated by specific sex-determining genes. The Aspergillus nidulans mating type gene matA and the human SRY (Sex-Determining Region Y) encode proteins containing a single HMG (high-mobility group) domain. Analysis of the amino-acid sequence of MatA and SRY transcription factors revealed significant structural similarity. The human SRY protein is able to functionally replace MatA and drives the sexual cycle in the fungus A. nidulans. Functional studies indicate that SRY drives early fruiting body development, and hybrid MatA protein carrying the SRY HMG box is fully capable of driving both early and late stages of sexual development, including gametogenesis. Our data suggest that SRY and MatA are both structurally and functionally related and conserved in regulating sexual processes. The fundamental mechanisms driving evolution of the genetic pathways underlying sex determination, sex chromosomes and sexual reproduction in eukaryotes appear similar.

  17. Community living long before man: fossil and living microbial mats and early life

    NASA Technical Reports Server (NTRS)

    Margulis, L.; Lopez Baluja, L.; Awramik, S. M.; Sagan, D.

    1986-01-01

    Microbial mats are layered communities of bacteria that form cohesive structures, some of which are preserved in sedimentary rocks as stromatolites. Certain rocks, approximately three and a half thousand million years old and representing the oldest known fossils, are interpreted to derive from microbial mats and to contain fossils of microorganisms. Modern microbial mats (such as the one described here from Matanzas, Cuba) and their fossil counterparts are of great interest in the interpretation of early life on Earth. Since examination of microbial mats and stromatolites increases our understanding of long-term stability and change, within the global environment, such structures should be protected wherever possible as natural science preserves. Furthermore, since they have existed virtually from the time of life's origin, microbial mats have developed exemplary mechanisms of local community persistence and may even play roles in the larger global environment that we do not understand.

  18. Enhancing the Mechanical Properties of Electrospun Nanofiber Mats through Controllable Welding at the Cross Points.

    PubMed

    Li, Haoxuan; Zhu, Chunlei; Xue, Jiajia; Ke, Qinfei; Xia, Younan

    2017-03-10

    This communication describes a simple and effective method for welding electrospun nanofibers at the cross points to enhance the mechanical properties of their nonwoven mats. The welding is achieved by placing a nonwoven mat of the nanofibers in a capped vial with the vapor of a proper solvent. For polycaprolactone (PCL) nanofibers, the solvent is dichloromethane (DCM). The welding can be managed in a controllable fashion by simply varying the partial pressure of DCM and/or the exposure time. Relative to the pristine nanofiber mat, the mechanical strength of the welded PCL nanofiber mat can be increased by as much as 200%. Meanwhile, such a treatment does not cause any major structural changes, including morphology, fiber diameter, and pore size. This study provides a generic method for improving the mechanical properties of nonwoven nanofiber mats, holding great potential in various applications.

  19. Anoxic carbon flux in photosynthetic microbial mats as revealed by metatranscriptomics.

    PubMed

    Burow, Luke C; Woebken, Dagmar; Marshall, Ian P G; Lindquist, Erika A; Bebout, Brad M; Prufert-Bebout, Leslie; Hoehler, Tori M; Tringe, Susannah G; Pett-Ridge, Jennifer; Weber, Peter K; Spormann, Alfred M; Singer, Steven W

    2013-04-01

    Photosynthetic microbial mats possess extraordinary phylogenetic and functional diversity that makes linking specific pathways with individual microbial populations a daunting task. Close metabolic and spatial relationships between Cyanobacteria and Chloroflexi have previously been observed in diverse microbial mats. Here, we report that an expressed metabolic pathway for the anoxic catabolism of photosynthate involving Cyanobacteria and Chloroflexi in microbial mats can be reconstructed through metatranscriptomic sequencing of mats collected at Elkhorn Slough, Monterey Bay, CA, USA. In this reconstruction, Microcoleus spp., the most abundant cyanobacterial group in the mats, ferment photosynthate to organic acids, CO2 and H2 through multiple pathways, and an uncultivated lineage of the Chloroflexi take up these organic acids to store carbon as polyhydroxyalkanoates. The metabolic reconstruction is consistent with metabolite measurements and single cell microbial imaging with fluorescence in situ hybridization and NanoSIMS.

  20. The nonlinear piezoelectric tuned vibration absorber

    NASA Astrophysics Data System (ADS)

    Soltani, P.; Kerschen, G.

    2015-07-01

    This paper proposes a piezoelectric vibration absorber, termed the nonlinear piezoelectric tuned vibration absorber (NPTVA), for the mitigation of nonlinear resonances of mechanical systems. The new feature of the NPTVA is that its nonlinear restoring force is designed according to a principle of similarity, i.e., the NPTVA should be an electrical analog of the nonlinear host system. Analytical formulas for the NPTVA parameters are derived using the homotopy perturbation method. Doing so, a nonlinear generalization of Den Hartog’s equal-peak tuning rule is developed for piezoelectric vibration absorbers.

  1. Super ionic conductive glass

    DOEpatents

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  2. Super ionic conductive glass

    DOEpatents

    Susman, Sherman; Volin, Kenneth J.

    1984-01-01

    An ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A.sub.1+x D.sub.2-x/3 Si.sub.x P.sub.3-x O.sub.12-2x/3, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  3. Seeing Glass Contractors Clearly.

    ERIC Educational Resources Information Center

    Deliberato, Jerry

    2003-01-01

    Offers seven tips for finding and working with an effective glass contractor. For example, schools should consider the company's reputation and longevity of service, and whether it has in-house engineering capabilities. (EV)

  4. Glass formation in microgravity

    NASA Technical Reports Server (NTRS)

    Ray, C. S.; Day, D. E.

    1987-01-01

    An account is given of containerless glass-forming experiments conducted aboard the Space Shuttle in 1985, using a single-axis acoustic levitator furnace apparatus. An attempt was made to obtain quantitative evidence for the suppression of heterogeneous nucleation/crystallization in containerless melts under microgravity conditions, as well as to study melt homogenization in the absence of gravity-driven convection and assess the feasibility of laser fusion target glass microsphere preparation with a microgravity apparatus of the present type. A ternary calcia-gallia-silica glass thus obtained indicated a 2-3-fold increase in glass-formation tendency for this material composition in microgravity, by comparison with 1g.

  5. Glass Stronger than Steel

    DOE R&D Accomplishments Database

    Yarris, Lynn

    2011-03-28

    A new type of damage-tolerant metallic glass, demonstrating a strength and toughness beyond that of steel or any other known material, has been developed and tested by a collaboration of researchers from Berkeley Lab and Caltech.

  6. Experimental indication for band gap widening of chalcopyrite solar cell absorbers after potassium fluoride treatment

    SciTech Connect

    Pistor, P.; Greiner, D.; Kaufmann, C. A.; Brunken, S.; Gorgoi, M.; Steigert, A.; Calvet, W.; Lauermann, I.; Klenk, R.; Unold, T.; Lux-Steiner, M.-C.

    2014-08-11

    The implementation of potassium fluoride treatments as a doping and surface modification procedure in chalcopyrite absorber preparation has recently gained much interest since it led to new record efficiencies for this kind of solar cells. In the present work, Cu(In,Ga)Se{sub 2} absorbers have been evaporated on alkali containing Mo/soda-lime glass substrates. We report on compositional and electronic changes of the Cu(In,Ga)Se{sub 2} absorber surface as a result of a post deposition treatment with KF (KF PDT). In particular, by comparing standard X-ray photoelectron spectroscopy and synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES), we are able to confirm a strong Cu depletion in the absorbers after the KF PDT which is limited to the very near surface region. As a result of the Cu depletion, we find a change of the valence band structure and a shift of the valence band onset by approximately 0.4 eV to lower binding energies which is tentatively explained by a band gap widening as expected for Cu deficient compounds. The KF PDT increased the open circuit voltage by 60–70 mV compared to the untreated absorbers, while the fill factor deteriorated.

  7. Graphite calorimetry for absorbed dose measurements in heavy-ion beams

    NASA Astrophysics Data System (ADS)

    Sakama, M.; Kanai, T.; Fukumura, A.

    In order to sophisticate the radiotherapy high accuracy knowledge of the absorbed dose delivered to the patient is essential The main methods of absolute dosimetry are indicated as follows a Dosimetry by ion chamber b Fricke dosimetry and c Calorimetry The calorimetry is most direct method of dosimetry due to direct measurement of energy deposit in principle and no requirement of information of radiation fields for the calibration Many countries tend to adopt the calorimetry to determine the standard absorbed dose to water and become to be capable of deciding the absorbed dose in precision of about 0 6 for photon and electron beams Despite the recent progress of particle therapy the parameters such as w-value and stopping power ratio for ionization chambers in the particles is not obtained accurately Therefore that causes uncertainty in determination of the absolute dose For this reason we developed a graphite calorimeter to obtain high precision absorbed dose and reduce the uncertainty for various beams When the absorbed dose of 1 Gy is irradiated to the sensitive volume the temperature rise is about 1 4 milliKelvins The performance require the resolution of plus or minus 7 micro Kelvins to measure it in precision of plus or minus 0 5 The stability within several micro Kelvins per minute is necessary to obtain measurable background The miniature glass bead thermistors were embedded in the sensitive volume to perform active control of temperature The resistance change of these thermistors is approximately 0 68 Ohms and 488 micro Ohms at

  8. Effects of green algal mats on bivalves in a New England mud flat

    NASA Astrophysics Data System (ADS)

    Thiel, M.; Stearns, L. M.; Watling, L.

    1998-03-01

    Concurrent with the spread of green algal mats on tidal flats, reports of macrofauna dieoffs under dense algal mats have increased in numbers. Bivalves seem to be particularly affected by persistent dense algal mats. Bivalve species with a long extendible siphon seem to be less affected underneath algal mats, but no distinction has been made in the past between species with short and those with long siphons, Mya arenaria and Macoma balthica, on an intertidal mudflat in New England. Abundances of M. arenaria declined substantially during the study period when a thick green algal mat covered the mudflat for several months. Numbers of the small bivalve Gemma gemma also decreased substantially, whereas abundances of M. balthica showed minimal variation during the time of algal coverage. In algae removal/addition experiments numbers of M. arenaria decreased, but effects were only significant in an algal addition to previously algal-free mudflat areas. Abundance of M. balthica did not change significantly in the algal removal/additition experiments. Over the time period of the experiment (9 weeks), M. arenaria showed measurable size increase in uncovered mudflat areas, but not underneath algal mats. Similarly, M. balthica only increased in size in the uncovered mudflat area. From these results it is concluded that M. balthica can survive time periods of dense algal coverage because it is able to penetrate through the algal mat with its long extendible siphon, and thus can reach well-oxygenated water layers above the mat. M. arenaria with its thick, less extendible, siphon cannot push through dense algal mats and therefore is more likely to die underneath persistent algal mats.

  9. The Response Regulator RcsB Activates Expression of Mat Fimbriae in Meningitic Escherichia coli

    PubMed Central

    Lehti, Timo A.; Heikkinen, Johanna; Korhonen, Timo K.

    2012-01-01

    The common colonization factor of Escherichia coli, the Mat (also termed ECP) fimbria, functions to advance biofilm formation on inert surfaces as well as bacterial adherence to epithelial cells and subsequent colonization. We used global mini-Tn5 transposon mutagenesis to identify novel regulators of biofilm formation by the meningitic E. coli isolate IHE 3034. Of the 4,418 transformants, we found 17 that were impaired in biofilm formation. Most of these mutants were affected in lipopolysaccharide synthesis and were reduced in growth but not in Mat fimbria expression. In contrast, two mutants grew well but did not express Mat fimbria. The insertions in these two mutants were located at different sites of the rcsB gene, which encodes a DNA-binding response regulator of the Rcs response regulon. The mutations abrogated temperature-dependent biofilm formation by IHE 3034, and the phenotype correlated with loss of mat expression. The defect in biofilm formation in the rcsB mutant was reversed upon complementation with rcsB as well as by overexpression of structural mat genes but not by overexpression of the fimbria-specific activator gene matA. Monitoring of the mat operon promoter activity with chromosomal reporter fusions showed that the RcsB protein and an RcsAB box in the mat regulatory region, but not RcsC, RcsD, AckA, and Pta, are essential for initiation of mat transcription. Gel retardation assays showed that RcsB specifically binds to the mat promoter DNA, which enables its function in promoting biofilm formation by E. coli. PMID:22522901

  10. Grain trapping by filamentous cyanobacterial and algal mats: implications for stromatolite microfabrics through time.

    PubMed

    Frantz, C M; Petryshyn, V A; Corsetti, F A

    2015-09-01

    Archean and Proterozoic stromatolites are sparry or fine-grained and finely laminated; coarse-grained stromatolites, such as many found in modern marine systems, do not appear until quite late in the fossil record. The cause of this textural change and its relevance to understanding the evolutionary history of stromatolites is unclear. Cyanobacteria are typically considered the dominant stromatolite builders through time, but studies demonstrating the trapping and binding abilities of cyanobacterial mats are limited. With this in mind, we conducted experiments to test the grain trapping and binding capabilities of filamentous cyanobacterial mats and trapping in larger filamentous algal mats in order to better understand grain size trends in stromatolites. Mats were cut into squares, inclined in saltwater tanks at angles from 0 to 75° (approximating the angle of lamina in typical stromatolites), and grains of various sizes (fine sand, coarse sand, and fine pebbles) were delivered to their surface. Trapping of grains by the cyanobacterial mats depended strongly on (i) how far filaments protruded from the sediment surface, (ii) grain size, and (iii) the mat's incline angle. The cyanobacterial mats were much more effective at trapping fine grains beyond the abiotic slide angle than larger grains. In addition, the cyanobacterial mats actively bound grains of all sizes over time. In contrast, the much larger algal mats trapped medium and coarse grains at all angles. Our experiments suggest that (i) the presence of detrital grains beyond the abiotic slide angle can be considered a biosignature in ancient stromatolites where biogenicity is in question, and, (ii) where coarse grains are present within stromatolite laminae at angles beyond the abiotic angle of slide (e.g., most modern marine stromatolites), typical cyanobacterial-type mats are probably not solely responsible for the construction, giving insight into the evolution of stromatolite microfabrics through time.

  11. Maté: a risk factor for oral and oropharyngeal cancer.

    PubMed

    Goldenberg, David

    2002-10-01

    Maté is a tea-like beverage consumed mainly in Argentina, Uruguay, Paraguay, southern Brazil and to a lesser degree in other areas of the world such as Germany, Syria, Lebanon and Northern Israel. It is brewed from the dried leaves and stemlets of the perennial tree Ilex paraguarensis ("yerba mate") a species that belongs to the Aquifoliaceae family. Maté consumption has been associated with an increased rate of oral and oropharyngeal cancers. The purpose of this study is to review the literature and discuss the role of Maté consumption in the development of oral and oropharyngeal cancer and the potential carcinogenic mechanisms. A review of the relevant literature linking Maté consumption with oral and oropharyngeal cancer and the carcinogenicity of Maté was performed. The search was performed using Medline, library catalogues, OCLC first search and ISI web of science databases. Case control studies on Maté drinking populations and, in vivo and in vitro studies on the carcinogenicity of Maté were reviewed. The populations reviewed in many of these studies also used alcohol and tobacco products confounding the influence of Maté as an independent risk factor. There is evidence in the literature that Maté consumption is in itself carcinogenic and plays a role in the development of cancers of the oral cavity and oropharynx. Although the exact mechanism of carcinogenesis is still unknown, available information suggests that Maté drinking should be considered one of the risk factors for oral and oropharyngeal cancer.

  12. Display innovations through glass

    NASA Astrophysics Data System (ADS)

    Hamilton, Lori L.

    2016-03-01

    Prevailing trends in thin, lightweight, high-resolution, and added functionality, such as touch sensing, continue to drive innovation in the display market. While display volumes grow, so do consumers’ need for portability, enhanced optical performance, and mechanical reliability. Technical advancements in glass design and process have enabled display innovations in these areas while supporting industry growth. Opportunities for further innovation remain open for glass manufacturers to drive new applications, enhanced functionality, and increased demand.

  13. Metallic glass composition

    DOEpatents

    Kroeger, Donald M.; Koch, Carl C.

    1986-01-01

    A metallic glass alloy that is either iron-based or nickel-based or based on a mixture of iron and nickel, containing lesser amounts of elements selected from the group boron, silicon carbon and phosphorous to which is added an amount of a ductility enhancing element selected from the group cerium, lanthanum, praseodymium and neodymium sufficient to increase ductility of the metallic glass upon annealing.

  14. Frangible glass canisters

    NASA Technical Reports Server (NTRS)

    Seifert, R.

    1972-01-01

    The need for a canister that can release its contents without disturbing the contents dynamically is discussed. The solution of this problem by the use of a frangible glass canister is considered. The basic theory applicable to frangible glass and the method of initiating a command flaw are discussed. A brief description of the test program and the results of a flight test are presented.

  15. Baseline LAW Glass Formulation Testing

    SciTech Connect

    Kruger, Albert A.; Mooers, Cavin; Bazemore, Gina; Pegg, Ian L.; Hight, Kenneth; Lai, Shan Tao; Buechele, Andrew; Rielley, Elizabeth; Gan, Hao; Muller, Isabelle S.; Cecil, Richard

    2013-06-13

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.

  16. Damages to optical silica glass: processes and mechanisms

    NASA Astrophysics Data System (ADS)

    Luo, Sheng-Nian; Zheng, Lianqing; An, Qi; Wu, Heng-An; Xia, Kaiwen; Ni, Sidao

    2007-01-01

    We present recent results of molecular dynamics simulations to illustrate the processes and mechanisms in damages to silica glass, including densification, cavitation, fragmentation and agglomeration via photon, electron, ion and neutron radiations and stresses. Radiation of glass creates point defects (vacancies and interstitials), and subsequent structure relaxation induces densification. Nanovoid below a certain size and rapid-quenching of silica liquid can also densify a glass. Hot spots due to photon-absorbing impurities in glass may cause local densification and cavitation as well. Densification can also be induced by compressional stress, and spall, by tensile stress. The densified glasses, regardless of the exact processes, share similar structural and vibrational properties, for example, the five-fold coordinated Si atoms. Densification is essentially a kinetic frustration during structure relaxation driven by excessive free energy, e.g., due to defects or stresses. The point-defect mechanism is dominant for densification without compression and complemented by thermal spike mechanism in thermal processes. Defects, thermal effects and stresses may interplay in a general damage process in silica glass.

  17. Neutron detector using sol-gel absorber

    DOEpatents

    Hiller, John M.; Wallace, Steven A.; Dai, Sheng

    1999-01-01

    An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

  18. Containerless synthesis of interesting glasses

    NASA Technical Reports Server (NTRS)

    Weinberg, Michael C.

    1990-01-01

    One aspect of containerless glass experimentation was thoroughly examined: glass forming ability. It is argued that although containerless processing will abet glass formation, other ground-based methods can do the job better. However, these methods have limitations, such as sample dimensions and concomitant ability to make property measurements. Most importantly, perhaps, is the observation that glass properties are a function of preparation procedure. Thus, it seems as though there still is an argument for use of containerless processing for glass forming.

  19. On the strength of glasses

    PubMed Central

    Wisitsorasak, Apiwat; Wolynes, Peter G.

    2012-01-01

    The remarkable strength of glasses is examined using the random first order transition theory of the glass transition. The theory predicts that strength depends on elastic modulus but also on the configurational energy frozen in when the glass is prepared. The stress catalysis of cooperative rearrangements of the type responsible for the supercooled liquid’s high viscosity account quantitatively for the measured strength of a range of metallic glasses, silica, and a polymer glass. PMID:22988070

  20. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  1. Energy absorber uses expanded coiled tube

    NASA Technical Reports Server (NTRS)

    Johnson, E. F.

    1972-01-01

    Mechanical shock mitigating device, based on working material to its failure point, absorbs mechanical energy by bending or twisting tubing. It functions under axial or tangential loading, has no rebound, is area independent, and is easy and inexpensive to build.

  2. Neutron absorbing coating for nuclear criticality control

    DOEpatents

    Mizia, Ronald E.; Wright, Richard N.; Swank, William D.; Lister, Tedd E.; Pinhero, Patrick J.

    2007-10-23

    A neutron absorbing coating for use on a substrate, and which provides nuclear criticality control is described and which includes a nickel, chromium, molybdenum, and gadolinium alloy having less than about 5% boron, by weight.

  3. Mechanism of mechanical fatigue of silica glass. Final technical report, July 1985--June 1995

    SciTech Connect

    Tomozawa, M.

    1995-08-01

    Objective is to study the static fatigue mechanism of silica glasses such as optical communication fibers. It is shown that the strength increase by thermal or hydrothermal treatment can be explained by formation of blunt crack tips. Specimens with blunt cracks exhibited fatigue only in water and NH3. While fatigue of glasses with sharp cracks involves only crack propagation, that of glasses with blunt cracks involves both crack initiation and propagation. Nonaqueous liquids can be adsorbed on the glass surface only, thus can aid crack propagation only. Water/NH3 can exhibit both adsorption and diffusion, and the ability of water to initiate a crack appears related to its diffusion into the glass. Mechanical fatigue of pristine silica fibers takes place in water but is not expected in nonaqueous liquids. Water entry into silica glass is accelerated by applied stress. Water entry (diffusion) into silica glasses at low temperatures was found closely coupled with structural relaxation of the glass, which lowers the fictive temperature. The relaxation can be monitored by simple IR spectroscopy; IR absorbance measures the fictive temperature over the entire thickness while IR reflection measures that of the surface. By combining IR reflection peak position measurement and successive etching, the depth profile of the fictive temperature can be determined. This was done in a communication fiber and in a specimen heat treated below the glass transition temperature. Glasses with higher fictive temperatures exhibit greater fatigue resistance.

  4. Porous absorber for solar air heaters

    SciTech Connect

    Finch, J.A.

    1980-09-10

    A general discussion of the factors affecting solar collector performance is presented. Bench scale tests done to try to determine the heat transfer characteristics of various screen materials are explained. The design, performance, and evaluation of a crude collector with a simple screen stack absorber is treated. The more sophisticated absorber concept, and its first experimental approximation is examined. A short summary of future plans for the collector concept is included. (MHR)

  5. Multilayer Radar Absorbing Non-Woven Material

    NASA Astrophysics Data System (ADS)

    Dedov, A. V.; Nazarov, V. G.

    2016-06-01

    We study the electrical properties of multilayer radar absorbing materials obtained by adding nonwoven sheets of dielectric fibers with an intermediate layer of electrically conductive carbon fibers. Multilayer materials that absorb electromagnetic radiation in a wide frequency range are obtained by varying the content of the carbon fibers. The carbon-fiber content dependent mechanism of absorption of electromagnetic radiation by sheets and multilayer materials is considered.

  6. Non-absorbed Antibiotics for IBS

    DTIC Science & Technology

    2012-03-16

    absorbed antibiotic rifaximin for nonconstipated irritable bowel syndrome (IBS). This effort adds to the body of literature from other, smaller studies that...have demonstrated clinical efficacy for IBS with rifaximin . Non-absorbed antibiotics have been endorsed by the American College of Gastroenterology... rifaximin 400 mg three times daily for 10 days or placebo. During the initial 2 weeks of therapy and the subsequent 10 weeks of follow-up rifaximin

  7. Structured metal film as a perfect absorber.

    PubMed

    Xiong, Xiang; Jiang, Shang-Chi; Hu, Yu-Hui; Peng, Ru-Wen; Wang, Mu

    2013-08-07

    A new type of absorber, a four-tined fish-spear-like resonator (FFR), constructed by the two-photon polymerization process, is reported. An absorbance of more than 90% is experimentally realized and the resonance occurs in the space between the tines. Since a continuous layer of metallic thin film covers the structure, it is perfectly thermo- and electroconductive, which is the mostly desired feature for many applications.

  8. Glass microsphere lubrication

    NASA Technical Reports Server (NTRS)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  9. DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

    SciTech Connect

    Adamson, D; Bradley Pickenheim, B

    2008-11-24

    DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from DWPF and is nominally -45+200 mesh. The spherical glass beads did not have a negative impact on the frit transfer system. The transferring of the spherical glass beads was much easier than the glass frit. It was difficult to create a plug with glass bead slurry in the pilot transfer system. When a small plug occurred from setting overnight with the spherical glass beads, the plug was easy to displace using only the pump. In the case of creating a man made plug in a vertical line, by filling the line with spherical glass beads and allowing the slurry to settle for days, the plug was easy to remove by using flush water. The glass frit proved to be much more difficult to transfer when compared to the spherical glass beads. The glass frit impacted the transfer system to the point

  10. Radar Absorbing Materials for Cube Stealth Satellite

    NASA Astrophysics Data System (ADS)

    Micheli, D.; Pastore, R.; Vricella, A.; Marchetti, M.

    A Cube Stealth Satellite is proposed for potential applications in defense system. Particularly, the faces of the satellite exposed to the Earth are made of nanostructured materials able to absorb radar surveillance electromagnetic waves, conferring stealth capability to the cube satellite. Microwave absorbing and shielding material tiles are proposed using composite materials consisting in epoxy-resin and carbon nanotubes filler. The electric permittivity of the composite nanostructured materials is measured and discussed. Such data are used by the modeling algorithm to design the microwave absorbing and the shielding faces of the cube satellite. The electromagnetic modeling takes into account for several incidence angles (0-80°), extended frequency band (2-18 GHz), and for the minimization of the electromagnetic reflection coefficient. The evolutionary algorithm used for microwave layered microwave absorber modeling is the recently developed Winning Particle Optimization. The mathematical model of the absorbing structure is finally experimentally validated by comparing the electromagnetic simulation to the measurement of the manufactured radar absorber tile. Nanostructured composite materials manufacturing process and electromagnetic reflection measurements methods are described. Finally, a finite element method analysis of the electromagnetic scattering by cube stealth satellite is performed.

  11. Absorbance changes of carotenoids in different solvents.

    PubMed

    Zang, L Y; Sommerburg, O; van Kuijk, F J

    1997-01-01

    Carotenoids are typically measured in tissues with the high performance liquid chromatography (HPLC) and quantitation is usually done by calibrating with stock solutions in solvents. Four carotenoids including lutein, zeaxanthin, lycopene and beta-carotene were dissolved in hexane and methanol respectively, and their absorbance characteristics were compared. Lutein shows absorbance spectra that are almost independent of solvents at various concentrations. Spectra of zeaxanthin, lycopene and beta-carotene were found to be more solvent-dependent. The absorbance of zeaxanthin at lambda max is about approximately 2 times larger in methanol than in hexane at the higher concentrations, and increased non-linearly with increasing concentration in hexane. The absorbance of lycopene at lambda max in hexane is approximately 4 fold larger than in methanol, but the absorbance of the methanol sample can be recovered by re-extracting this sample in hexane. The absorbance of beta-carotene in hexane is larger than in methanol, and increased linearly with increasing concentration. But beta-carotene showed a non-linear concentration effect in methanol. There are very small variations in lambda max for all four carotenoids between hexane and methanol, due to differences in molar extinction coefficients. The non-linear concentration effects for these carotenoids are probably due to differences in solubility leading to the formation of microcrystals. Thus, care should be taken with quantitation of tissue carotenoid values, when they depend on measurement of concentrations in stock solutions.

  12. Perfect terahertz absorber using fishnet based metafilm

    SciTech Connect

    Azad, Abul Kalam; Shchegolkov, Dmitry Yu; Chen, Houtong; Taylor, Antoinette; Smirnova, E I; O' Hara, John F

    2009-01-01

    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  13. Low-temperature evaporative glass scoring using a single-mode ytterbium fiber laser

    NASA Astrophysics Data System (ADS)

    Tu, J. F.; Riley, P. E. B.

    2013-06-01

    Glass cutting is increasingly important in industry to cut glass into various sizes for high definition televisions, cell phones, laptops, and tablet computers. A conventional mechanical cutter is usually used to score the glass before a bending force is applied to separate the glass along the scoring mark. This paper presents a laser glass scoring technique aimed at replacing the mechanical cutter to reduce cracks. This scoring technique, denoted as the Low-temperature Evaporative Glass Scoring process (LEGS), is different because laser energy is not directly absorbed by the glass. To achieve the proposed laser scoring, a laser beam is focused through the glass onto a metal substrate. The metal substrate absorbs the laser energy to generate a metal vapor to etch the glass, forming a scoring mark. The feasibility of this glass scoring technique is demonstrated using a continuous-wave fiber laser, at a low power of 60 W, and a 7075-T6 Aluminum alloy plate as the metal substrate. When the laser beam scans across the substrate, the laser energy creates a quasi-static aluminum molten pool, covered by an aluminum vapor at a temperature about 3000 K. At an optimal setting of 51 μm gap distance, 60 W laser power, and 6 mm/s scoring speed, a uniform scoring mark of 37 μm width and 120 μm depth was successfully generated on a piece of soda-lime glass without visible micro-cracks. The paper also discussed the uncertainties and their remedies involved in the LEGS process. To facilitate the process design, a model for predicting the aluminum vapor temperature was developed. This model accounted for the laser focus, reflection, absorption and transmission, laser energy distribution, and the aluminum melting and vaporization processes. Finally, this model was validated by comparing the actual melt depth of the aluminum substrate with the one predicted by the model.

  14. Implications of a 3.472-3.333 Gyr-old subaerial microbial mat from the Barberton greenstone belt, South Africa for the UV environmental conditions on the early Earth.

    PubMed

    Westall, Frances; de Ronde, Cornel E J; Southam, Gordon; Grassineau, Nathalie; Colas, Maggy; Cockell, Charles; Lammer, Helmut

    2006-10-29

    Modelling suggests that the UV radiation environment of the early Earth, with DNA weighted irradiances of about three orders of magnitude greater than those at present, was hostile to life forms at the surface, unless they lived in specific protected habitats. However, we present empirical evidence that challenges this commonly held view. We describe a well-developed microbial mat that formed on the surface of volcanic littoral sediments in an evaporitic environment in a 3.5-3.3Ga-old formation from the Barberton greenstone belt. Using a multiscale, multidisciplinary approach designed to strongly test the biogenicity of potential microbial structures, we show that the mat was constructed under flowing water by 0.25 microm filaments that produced copious quantities of extracellular polymeric substances, representing probably anoxygenic photosynthesizers. Associated with the mat is a small colony of rods-vibroids that probably represent sulphur-reducing bacteria. An embedded suite of evaporite minerals and desiccation cracks in the surface of the mat demonstrates that it was periodically exposed to the air in an evaporitic environment. We conclude that DNA-damaging UV radiation fluxes at the surface of the Earth at this period must either have been low (absorbed by CO2, H2O, a thin organic haze from photo-dissociated CH4, or SO2 from volcanic outgassing; scattered by volcanic, and periodically, meteorite dust, as well as by the upper layers of the microbial mat) and/or that the micro-organisms exhibited efficient gene repair/survival strategies.

  15. Implications of a 3.472–3.333 Gyr-old subaerial microbial mat from the Barberton greenstone belt, South Africa for the UV environmental conditions on the early Earth

    PubMed Central

    Westall, Frances; de Ronde, Cornel E.J; Southam, Gordon; Grassineau, Nathalie; Colas, Maggy; Cockell, Charles; Lammer, Helmut

    2006-01-01

    Modelling suggests that the UV radiation environment of the early Earth, with DNA weighted irradiances of about three orders of magnitude greater than those at present, was hostile to life forms at the surface, unless they lived in specific protected habitats. However, we present empirical evidence that challenges this commonly held view. We describe a well-developed microbial mat that formed on the surface of volcanic littoral sediments in an evaporitic environment in a 3.5–3.3 Ga-old formation from the Barberton greenstone belt. Using a multiscale, multidisciplinary approach designed to strongly test the biogenicity of potential microbial structures, we show that the mat was constructed under flowing water by 0.25 μm filaments that produced copious quantities of extracellular polymeric substances, representing probably anoxygenic photosynthesizers. Associated with the mat is a small colony of rods–vibroids that probably represent sulphur-reducing bacteria. An embedded suite of evaporite minerals and desiccation cracks in the surface of the mat demonstrates that it was periodically exposed to the air in an evaporitic environment. We conclude that DNA-damaging UV radiation fluxes at the surface of the Earth at this period must either have been low (absorbed by CO2, H2O, a thin organic haze from photo-dissociated CH4, or SO2 from volcanic outgassing; scattered by volcanic, and periodically, meteorite dust, as well as by the upper layers of the microbial mat) and/or that the micro-organisms exhibited efficient gene repair/survival strategies. PMID:17008224

  16. On the study of crack-initiation fracture toughness of fiber glass asphalt shingles

    SciTech Connect

    Shiao, M.L.

    1999-07-01

    The fracture behavior of fiber glass asphalt shingles was examined by measuring their J-integral fracture toughness at crack initiation. The corresponding fracture mechanisms were also studied by in situ fracture observation and by scanning electron microscopy. The applicability of using J-integral fracture toughness to characterize asphalt shingles was discussed and its relationships to other mechanical properties was established. The results indicated that the fracture toughness at crack initiation can be accurately measured for fiber glass shingles and the values may be used to characterize their cracking resistance. Fracture toughness measured from various shingle samples was found to correlate to the shingle's tensile toughness and to its tear strength. Preliminary results on fracture mechanisms suggested that failure in the asphalt coatings by micro-cavitation may be the controlling event leading to crack advance. The importance of the glass fiber mat on a shingle's resistance to fracture was also discussed.

  17. Spatially-resolved carbon flow through a hypersaline phototrophic microbial mat

    NASA Astrophysics Data System (ADS)

    Moran, J.; Lindemann, S. R.; Cory, A. B.; Courtney, S.; Cole, J. K.; Fredrickson, J.

    2013-12-01

    Hot Lake is a hypersaline, meromictic lake located in an endorheic basin in north-central Washington. Low annual rainfall and high evaporation rates contribute to the lake's high salinity. The predominant dissolved salt is magnesium sulfate, of which monimolimnion waters may seasonally exceed 2 M concentrations. Induced by its high salinity and meromictic nature, Hot Lake displays an inverse thermal gradient with deep horizons seasonally exceeding 50 °C. Despite extreme conditions, dense benthic microbial mats composed of cyanobacteria, anoxygenic photoheterotrophs, and bacterial heterotroph populations develop in the lake. These mats can exceed 1 cm in thickness and display vertical stratification in color due to bacterial pigmentation. Typical mat stratification includes an orange surface layer underlain by green and purple layers at increasing depth. Carbonates, including aragonite and magnesite, are observed within the mat and their formation is likely induced or influenced by microbial metabolic activities and associated pH excursions. We are exploring the role Hot Lake's microbial mats play in carbon cycling. Cyanobacteria are the dominant CO2-fixing organisms in the mat and we seek to understand the spatial and metabolic controls on how the carbon initially fixed by mat cyanobacteria is transferred to associated heterotrophic populations spread throughout the mat strata. Secondly, we seek to understand the overall net carbon balance of the mat through a growing season. We are using a stable isotope probing approach for assessing carbon uptake and migration through representative mat samples. We performed a series of ex situ incubations of freshly harvested mat samples in lake water amended with 13C-labeled bicarbonate or substrates commonly consumed by heterotrophs (including acetate and glucose) and using multiple stable isotope techniques to track label uptake, residence time, remineralization, and location within the mat. In addition to bulk isotope

  18. Development Of Porous Glass Fiber Optic Sensors

    NASA Astrophysics Data System (ADS)

    Macedo, P. B.; Barkatt, Aa.; Feng, X.; Finger, S. M.; Hojaji, H.; Laberge, N.; Mohr, R.; Penafiel, M.; Saad, E.

    A method for producing rugged, continuous porous glass fiber optic sensors was developed. pH and temperature sensors based on this technology have been successfully produced. The sensor portion of the fiber is made porous by selective leaching of a specially formulated borosilicate glass fiber. This results in a strong, monolithic structure where the sensor portion of the fiber remains integrally attached to the rest of the fiber (which acts as a light pipe), essentially eliminating losses at the sensor-light pipe interface. Pore size in the sensor can be controllably varied by modifying heat treatment conditions, making these sensors suitable for chemical concentration measurements in liquids and gases. Appropriate dyes were chemically bonded by silanization to the large interior surface area of the porous sensors to produce the pH and temperature sensors. Cresol red and phenol red were used for pH and pinacyanol chloride was used for temperature sensing. The sensitivity of these devices can be controlled by varying the concentration of the chemically bonded dye and the length of the porous region. Optical absorbance measurements were made in the visible range. The tip of the sensors was coated with a thin, porous layer of gold to reflect the incident light, resulting in a double pass across the porous sensor. Experimental measurements were made over a pH range of 3 to 8 and a temperature range of 28-70 C. These porous glass fiber optic sensors were found to be rugged and reliable due to their monolithic structure and large interior surface area for attachment of active species. A broad range of sensors based on this technology could be developed by using different active species, such as enzymes and other biochemicals, which could be bonded to the interior surface of the porous glass sensor.

  19. Complex polar lipids of a hot spring cyanobacterial mat and its cultivated inhabitants

    NASA Technical Reports Server (NTRS)

    Ward, D. M.; Panke, S.; Kloppel, K. D.; Christ, R.; Fredrickson, H.

    1994-01-01

    The complex polar lipids of the hot spring cyanobacterial mat in the 50 to 55 degrees C region of Octopus Spring, Yellowstone National Park, and of thermophilic bacteria cultivated from this or similar habitats, were compared in an attempt to understand the microbial sources of the major lipid biomarkers in this community. Intact complex lipids were analyzed directly by fast atom bombardment mass spectrometry (FAB-MS), two-dimensional thin-layer chromatography (TLC), and combined TLC-FAB-MS. FAB-MS and TLC gave qualitatively similar results, suggesting that the mat contains major lipids most like those of the cyanobacterial isolate we studied, Synechococcus sp. strain Y-7c-s. These include monoglycosyl, diglycosyl, and sulfoquinosovyl diglycerides (MG, DG, and SQ, respectively) and phosphatidyl glycerol (PG). Though Chloroflexus aurantiacus also contains MG, DG, and PG, the fatty acid chain lengths of mat MGs, DGs, and PGs resemble more those of cyanobacterial than green nonsulfur bacterial lipids. FAB-MS spectra of the lipids of nonphototrophic bacterial isolates were distinctively different from those of the mat and phototrophic isolates. The lipids of these nonphototrophic isolates were not detected in the mat, but most could be detected when added to mat samples. The mat also contains major glycolipids and aminophospholipids of unknown structure and origin. FAB-MS and TLC did not always give quantitatively similar results. In particular, PG and SQ may give disproportionately high FAB-MS responses.

  20. Antimicrobial Activity of Silver Ions Released from Zeolites Immobilized on Cellulose Nanofiber Mats.

    PubMed

    Rieger, Katrina A; Cho, Hong Je; Yeung, Hiu Fai; Fan, Wei; Schiffman, Jessica D

    2016-02-10

    In this study, we exploit the high silver ion exchange capability of Linde Type A (LTA) zeolites and present, for the first time, electrospun nanofiber mats decorated with in-house synthesized silver (Ag(+)) ion exchanged zeolites that function as molecular delivery vehicles. LTA-Large zeolites with a particle size of 6.0 μm were grown on the surface of the cellulose nanofiber mats, whereas LTA-Small zeolites (0.2 μm) and three-dimensionally ordered mesoporous-imprinted (LTA-Meso) zeolites (0.5 μm) were attached to the surface of the cellulose nanofiber mats postsynthesis. After the three zeolite/nanofiber mat assemblies were ion-exchanged with Ag(+) ions, their ion release profiles and ability to inactivate Escherichia coli (E. coli) K12 were evaluated as a function of time. LTA-Large zeolites immobilized on the nanofiber mats displayed more than an 11 times greater E. coli K12 inactivation than the Ag-LTA-Large zeolites that were not immobilized on the nanofiber mats. This study demonstrates that by decorating nanometer to micrometer scale Ag(+) ion-exchanged zeolites on the surface of high porosity, hydrophilic cellulose nanofiber mats, we can achieve a tunable release of Ag(+) ions that inactivate bacteria faster and are more practical to use in applications over powder zeolites.

  1. The Ububele Baby Mat intervention: facilitating meaning in a multi-cultural context.

    PubMed

    Nortje, Michelle

    2016-07-01

    This paper expands on the continuing understanding of the Ububele Baby Mat Project - a community-based parent-infant mental health intervention now offered at six primary healthcare clinics in Alexandra, Johannesburg. This paper describes the influence of cultural diversity and the complex layers of meaning-making involved in the Baby Mat intervention. Meaning-making is a collaborative process between the caregiver-infant dyad's cultural beliefs and experiences, the Baby Mat couple's relationship, knowledge and skills, and the additional minds of the multicultural supervision group. This paper aims to clarify these three layers of co-constructed meaning-making involved in the Baby Mat intervention. Three central themes are thus presented to discuss the impact of multi-cultural, multi-racial and multi-lingual therapeutic dyads on the process of the Baby Mat intervention. These core themes are the verbal and non-verbal meanings of presenting problems brought by caregiver-infant dyads; the value and obstacles involved within a cross-cultural baby mat couple; and the significance of a reflective group supervision space. Case extracts are used to illustrate these processes of multiple minds at play during a Baby Mat session.

  2. Spectral Irradiance and Distribution of Pigments in a Highly Layered Marine Microbial Mat

    PubMed Central

    Pierson, Beverly K.; Sands, Vicki M.; Frederick, Judith L.

    1990-01-01

    The spectral irradiance from 400 to 1,100 nm was measured with depth in the intertidal sand mats at Great Sippewissett Salt Marsh, Mass. These mats contained at least four distinct layers, composed of cyanobacteria, purple sulfur bacteria containing bacteriochlorophyll a (Bchl a), purple sulfur bacteria containing Bchl b, and green sulfur bacteria. Spectral irradiance was measured directly by layering sections of mat on a cosine receptor. Irradiance was also approximated by using a calibrated fiber-optic tip. With the tip, irradiance measurements could be obtained at depth intervals less than 250 μm. The irradiance spectra were correlated qualitatively and quantitatively with the distribution of the diverse chlorophyll pigments in this mat and were compared with spectra recorded in plain sand lacking pigmented phototrophs. We found that the shorter wavelengths (400 to 550 nm) were strongly attenuated in the top 2 mm of the mat. The longer wavelengths (red and near infrared) penetrated to much greater depths, where they were attenuated by Bchl a, b, and c-containing anoxygenic phototrophic bacteria. The specific attenuation bands in the irradiance spectra correlated with the specific in vivo absorption bands of the Bchl-protein complexes in the bacteria. We concluded that the pigments in the phototrophs had a profound affect on the light environment within the mat. It seems likely that the diverse Bchl-protein complexes found in the anoxygenic phototrophs evolved in dense mat environments as a result of competition for light. PMID:16348246

  3. Cantera Integration with the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)

    NASA Technical Reports Server (NTRS)

    Lavelle, Thomas M.; Chapman, Jeffryes W.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei

    2014-01-01

    NASA Glenn Research Center (GRC) has recently developed a software package for modeling generic thermodynamic systems called the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink(Registered TradeMark) (The MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The current version of T-MATS (v1.0.1) uses tabular data for providing information about a specific mixture of air, water (humidity), and hydrocarbon fuel in calculations of thermodynamic properties. The capabilities of T-MATS can be expanded by integrating it with the Cantera thermodynamic package. Cantera is an object-oriented analysis package that calculates thermodynamic solutions for any mixture defined by the user. Integration of Cantera with T-MATS extends the range of systems that may be modeled using the toolbox. In addition, the library of elements released with Cantera were developed using MATLAB native M-files, allowing for quicker prototyping of elements. This paper discusses how the new Cantera-based elements are created and provides examples for using T-MATS integrated with Cantera.

  4. Cantera Integration with the Toolbox for Modeling and Analysis of Thermodynamic Systems (T-MATS)

    NASA Technical Reports Server (NTRS)

    Lavelle, Thomas M.; Chapman, Jeffryes W.; May, Ryan D.; Litt, Jonathan S.; Guo, Ten-Huei

    2014-01-01

    NASA Glenn Research Center (GRC) has recently developed a software package for modeling generic thermodynamic systems called the Toolbox for the Modeling and Analysis of Thermodynamic Systems (T-MATS). T-MATS is a library of building blocks that can be assembled to represent any thermodynamic system in the Simulink (The MathWorks, Inc.) environment. These elements, along with a Newton Raphson solver (also provided as part of the T-MATS package), enable users to create models of a wide variety of systems. The current version of T-MATS (v1.0.1) uses tabular data for providing information about a specific mixture of air, water (humidity), and hydrocarbon fuel in calculations of thermodynamic properties. The capabilities of T-MATS can be expanded by integrating it with the Cantera thermodynamic package. Cantera is an object-oriented analysis package that calculates thermodynamic solutions for any mixture defined by the user. Integration of Cantera with T-MATS extends the range of systems that may be modeled using the toolbox. In addition, the library of elements released with Cantera were developed using MATLAB native M-files, allowing for quicker prototyping of elements. This paper discusses how the new Cantera-based elements are created and provides examples for using T-MATS integrated with Cantera.

  5. Antimicrobial activity of electrospun poly(butylenes succinate) fiber mats containing PVP-capped silver nanoparticles.

    PubMed

    Tian, Ligang; Wang, Pingli; Zhao, Zhiguo; Ji, Junhui

    2013-12-01

    In this study, biodegradable poly(butylenes succinate) (PBS) fiber mats containing silver nanoparticles (AgNPs) were prepared by the electrospinning process. Small AgNPs (<10 nm) were simply synthesized using polyvinylpyrrolidone as the capping agent as well as the reductant. The morphology of the PBS-AgNPs fiber mats and the distribution of the AgNPs were well characterized by TEM and SEM. The release of Ag from the PBS fiber mats was quantitively determined by ICP. The PBS fiber mats with 0.29 % AgNPs content showed strong antimicrobial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli with the efficacy as high as 99 %. The effective bactericidal activity on E. coli was demonstrated for a short contacting time with the PBS-AgNPs fiber mats. In addition, the long-term release performance of Ag from the fiber mats can keep inhibiting the bacterial growth in the mats over a long period of time.

  6. Electrospun chitosan-based nanocomposite mats reinforced with chitin nanocrystals for wound dressing.

    PubMed

    Naseri, Narges; Algan, Constance; Jacobs, Valencia; John, Maya; Oksman, Kristiina; Mathew, Aji P

    2014-08-30

    The aim of this study was to develop electrospun chitosan/polyethylene oxide-based randomly oriented fiber mats reinforced with chitin nanocrystals (ChNC) for wound dressing. Microscopy studies showed porous mats of smooth and beadless fibers with diameters between 223 and 966 nm. The addition of chitin nanocrystals as well as crosslinking had a positive impact on the mechanical properties of the mats, and the crosslinked nanocomposite mats with a tensile strength of 64.9 MPa and modulus of 10.2 GPa were considered the best candidate for wound dressing application. The high surface area of the mats (35 m(2)g(-1)) was also considered beneficial for wound healing. The water vapor transmission rate of the prepared mats was between 1290 and 1,548 gm(-2)day(-1), and was in the range for injured skin or wounds. The electrospun fiber mats showed compatibility toward adipose derived stem cells, further confirming their potential use as wound dressing materials.

  7. MATS: a Bayesian framework for flexible detection of differential alternative splicing from RNA-Seq data

    PubMed Central

    Shen, Shihao; Park, Juw Won; Huang, Jian; Dittmar, Kimberly A.; Lu, Zhi-xiang; Zhou, Qing; Carstens, Russ P.; Xing, Yi

    2012-01-01

    Ultra-deep RNA sequencing has become a powerful approach for genome-wide analysis of pre-mRNA alternative splicing. We develop MATS (multivariate analysis of transcript splicing), a Bayesian statistical framework for flexible hypothesis testing of differential alternative splicing patterns on RNA-Seq data. MATS uses a multivariate uniform prior to model the between-sample correlation in exon splicing patterns, and a Markov chain Monte Carlo (MCMC) method coupled with a simulation-based adaptive sampling procedure to calculate the P-value and false discovery rate (FDR) of differential alternative splicing. Importantly, the MATS approach is applicable to almost any type of null hypotheses of interest, providing the flexibility to identify differential alternative splicing events that match a given user-defined pattern. We evaluated the performance of MATS using simulated and real RNA-Seq data sets. In the RNA-Seq analysis of alternative splicing events regulated by the epithelial-specific splicing factor ESRP1, we obtained a high RT–PCR validation rate of 86% for differential exon skipping events with a MATS FDR of <10%. Additionally, over the full list of RT–PCR tested exons, the MATS FDR estimates matched well with the experimental validation rate. Our results demonstrate that MATS is an effective and flexible approach for detecting differential alternative splicing from RNA-Seq data. PMID:22266656

  8. Acetylation of MAT IIα represses tumour cell growth and is decreased in human hepatocellular cancer

    PubMed Central

    Yang, Hong-Bin; Xu, Ying-Ying; Zhao, Xiang-Ning; Zou, Shao-Wu; Zhang, Ye; Zhang, Min; Li, Jin-Tao; Ren, Feng; Wang, Li-Ying; Lei, Qun-Ying

    2015-01-01

    Metabolic alteration is a hallmark of cancer. Dysregulation of methionine metabolism is implicated in human liver cancer. Methionine adenosyltransferase IIα (MAT IIα) is a key enzyme in the methionine cycle, catalysing the production of S-adenosylmethionine (SAM), a key methyl donor in cellular processes, and is associated with uncontrolled cell proliferation in cancer. Here we show that P300 acetylates MAT IIα at lysine residue 81 and destabilizes MAT IIα by promoting its ubiquitylation and subsequent proteasomal degradation. Conversely, histone deacetylase-3 deacetylates and stabilizes MAT IIα by preventing its proteasomal degradation. Folate deprivation upregulates K81 acetylation and destabilizes MAT IIα to moderate cell proliferation, whereas a single mutation at K81 reverses the proliferative disadvantage of cancer cells upon folate deprivation. Moreover, MAT IIα K81 acetylation is decreased in human hepatocellular cancer. Collectively, our study reveals a novel mechanism of MAT IIα regulation by acetylation and ubiquitylation, and a direct functional link of this regulation to cancer development. PMID:25925782

  9. The micromorphology of Younger Dryas-aged black mats from Nevada, Arizona, Texas and New Mexico

    NASA Astrophysics Data System (ADS)

    Harris-Parks, Erin

    2016-01-01

    Black mats are organic-rich sediments and soils that form in wet environments associated with spring discharge. Micromorphological and geochemical analyses of 25 black mats dating to the Younger Dryas Chronozone (12.9-11.7 ka) and early Holocene were conducted to determine their composition and depositional environment. Samples were collected from Arizona, New Mexico, Texas and Nevada. Micromorphological analyses were conducted on thin sections using polarized and blue fluorescent light. These analyses determined that black mats contain humic acids, fine (5-20 μm) plant fragments, diatoms, phytoliths, and gastropods. The dominant type of organic matter in black mats is derived from herbaceous plants, contradicting previous studies that supported algal or charcoal sources. Differences in the micromorphological characteristics of the samples revealed that black mats formed as three different types, organic horizons, moist soils and, ponded sediments, depending on their topographic position in relation to the water table. The microscopic evidence found in black mats supports the presence of widespread wet environments in Nevada and Arizona during the Younger Dryas Chronozone, clearly indicating a sustained period of greater effective moisture, optimal for spring discharge and black mat formation.

  10. Organismal and spatial partitioning of energy and macronutrient transformations within a hypersaline mat.

    PubMed

    Mobberley, Jennifer M; Lindemann, Stephen R; Bernstein, Hans C; Moran, James J; Renslow, Ryan S; Babauta, Jerome; Hu, Dehong; Beyenal, Haluk; Nelson, William C

    2017-03-15

    Phototrophic mat communities are model ecosystems for studying energy cycling and elemental transformations because complete biogeochemical cycles occur over millimeter-to-centimeter scales. Characterization of energy and nutrient capture within hypersaline phototrophic mats has focused on specific processes and organisms, however little is known about community-wide distribution of and linkages between these processes. To investigate energy and macronutrient capture and flow through a structured community, the spatial and organismal distribution of metabolic functions within a compact hypersaline mat community from Hot Lake have been broadly elucidated through species-resolved metagenomics and geochemical, microbial diversity, and metabolic gradient measurements. Draft reconstructed genomes of 34 abundant organisms revealed three dominant cyanobacterial populations differentially distributed across the top layers of the mat suggesting niche separation along light and oxygen gradients. Many organisms contained diverse functional profiles, allowing for metabolic response to changing conditions within the mat. Organisms with partial nitrogen and sulfur metabolisms were widespread indicating dependence upon metabolite exchange. In addition, changes in community spatial structure were observed over the diel. These results indicate that organisms within the mat community have adapted to the temporally dynamic environmental gradients in this hypersaline mat through metabolic flexibility and fluid syntrophic interactions, including shifts in spatial arrangements.

  11. Design, Fabrication, and Testing of Composite Energy-Absorbing Keel Beams for General Aviation Type Aircraft

    NASA Technical Reports Server (NTRS)

    Kellas, Sotiris; Knight, Norman F., Jr.

    2002-01-01

    A lightweight energy-absorbing keel-beam concept was developed and retrofitted in a general aviation type aircraft to improve crashworthiness performance. The energy-absorbing beam consisted of a foam-filled cellular structure with glass fiber and hybrid glass/kevlar cell walls. Design, analysis, fabrication and testing of the keel beams prior to installation and subsequent full-scale crash testing of the aircraft are described. Factors such as material and fabrication constraints, damage tolerance, crush stress/strain response, seat-rail loading, and post crush integrity, which influenced the course of the design process are also presented. A theory similar to the one often used for ductile metal box structures was employed with appropriate modifications to estimate the sustained crush loads for the beams. This, analytical tool, coupled with dynamic finite element simulation using MSC.Dytran were the prime design and analysis tools. The validity of the theory as a reliable design tool was examined against test data from static crush tests of beam sections while the overall performance of the energy-absorbing subfloor was assessed through dynamic testing of 24 in long subfloor assemblies.

  12. Understanding the fiber tip thermal runaway present in 3 µm fluoride glass fiber lasers.

    PubMed

    Caron, Nicolas; Bernier, Martin; Faucher, Dominic; Vallée, Réal

    2012-09-24

    When the tip of a fluoride glass fiber is exposed to ambient air, water vapor reacts with the glass constituents, increasing the OH contaminants at the surface. These OH impurities then diffuse inside the glass according to Fick's laws. Laser radiation at around 3 µm is strongly absorbed by the OH contaminants, causing local heating of the fiber tip resulting in an increase of the diffusion process which ultimately leads to fiber tip destruction. We accurately model this phenomenon by combining the diffusion theory with a basic thermal equation. Experimental measurements are in agreement with the model predictions for a good range of operating conditions.

  13. Intrinsic Dosimetry: Elemental Composition Effects on the Thermoluminescence of Commercial Borosilicate Glass

    SciTech Connect

    Richard A. Clark; J. David Robertson; Jon M. Schwantes

    2013-12-01

    Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.

  14. Intrinsic Dosimetry. Elemental Composition Effects on the Thermoluminescence of Commercial Borosilicate Glass

    SciTech Connect

    Clark, Richard A.; Robertson, J. David; Schwantes, Jon M.

    2013-07-05

    Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering this dose in tandem with the physical characteristics of the radioactive material housed within the container, this method can provide enhanced pathway information for interdicted radioactive samples. Thermoluminescence (TL) dosimetry was used to measure ionizing radiation dose effects on stock borosilicate glass. Differences in TL glow curve shape and intensity were observed for glasses from different geographical origins. The different TL signatures strongly correlated with the concentration of alkaline earth metals and the ratio of sodium to the total amount of alkali metal present in the borosilicate glass.

  15. Evaluation of hydrophobic polyvinyl-alcohol formaldehyde sponges as absorbents for oil spill.

    PubMed

    Pan, Yanxiong; Shi, Kai; Peng, Chao; Wang, Weicai; Liu, Zhi; Ji, Xiangling

    2014-06-11

    Macroporous materials are a class of absorbents used for oil spill cleanup. In this article, novel macroporous and hydrophobic polyvinyl formaldehyde (PVF-H) sponges were prepared by the reaction of stearoyl chloride with hydroxyl groups of hydrophilic PVF sponge at different temperatures. Attenuated total reflectance-infrared (ATR-IR) spectroscopy confirmed the successfully anchoring of hydrophobic stearoyl groups on the PVF networks. Scanning electron microscopy (SEM) images demonstrated that the as-prepared PVF-H had interconnected open-cell structures, and mercury intrusion porosimetry indicated that the average pore size ranged from 60 to 90 μm and porosity was greater than 94.8%. Such PVF-H sponges can absorb oil products effectively, such as toluene, n-hexane, kerosene, soybean oil, hydraulic oil, and crude oil up to 13.7 g·g(-1) to 56.6 g·g(-1), and this level of absorption was approximately 2-4 times higher than that absorbed by commercial polypropylene nonwoven mat. In low-viscosity oils, the samples can reach the saturated absorption amount only in 1 min, but in higher-viscosity oils, absorption equilibrium can be reached in 10 min. In a simulated oil slick system, these macroporous and hydrophobic sponges can still maintain high oil absorption capacities within the range of 14.4 g·g(-1) to 57.6 g·g(-1), whereas a relatively low absorption rate (approximately 20 min) indicated high absorption performance and excellent selectivity in the oil-water mixture. In addition, the absorbed oils were collected effectively only through a simple squeeze. The PVF-H sponges were subjected to 35 absorption-squeeze cycles and exhibited good reusability and 90% recovery for oils. The samples prepared at different temperatures differed in their absorption capacities to some extent. However, this new kind of macroporous and PVF-H sponges had excellent absorption performance on oil products.

  16. Controlled release of cefazolin sodium antibiotic drug from electrospun chitosan-polyethylene oxide nanofibrous Mats.

    PubMed

    Fazli, Yousef; Shariatinia, Zahra

    2017-02-01

    Antimicrobial electrospun chitosan-polyethylene oxide (CS-PEO) nanofibrous mats containing cefazolin, fumed silica (F. silica) and cefazolin-loaded fumed silica nanoparticles (NPs) were produced for biomedical applications. The FE-SEM images revealed that the F. silica and F. silica-cefazolin NPs had average diameters of 40±10 and 60±15nm, respectively. Also, the fibers diameters were approximately 160±30, 90±20 and 70±15nm for the pure CS-PEO, CS-PEO-1% F. silica and CS-PEO-1% F. silica-0.5% cefazolin nanofibrous mats, respectively indicating addition of F. silica and cefazolin loaded F. silica NPs to the CS-PEO mat led to decreasing the nanofiber diameter. Both of the CS-PEO mats containing 2.5% cefazolin and 1% F. silica-0.50% cefazolin showed 100% bactericidal activities against both S. aureus and E. coli bacteria. The cefazolin release from mats was sharply increased within first 24 and 6hours for the CS-PEO mats including 2.5% cefazolin and 1% F. silica-0.50% cefazolin but after that the drug was released very slowly. The improved hydrophilicity, higher tensile strength and sustained drug release for CS-PEO-1% F. silica-0.50% cefazolin suggested that it was the best nanocomposite tissue/device for biomedical applications among the mats CS-PEO-2.5% cefazolin and CS-PEO-1% F. silica. The wound healing ability of the CS-PEO-F. silica-cefazolin mat was evaluated on the wounded skins of the female Wistar rats and it was shown that the wounded skins of the rats were almost entirely healed after ten days using this mat as a wound dressing scaffold.

  17. Effect of sticky mat usage in control of nosocomial infection in Motahary Burn Hospital

    PubMed Central

    Dahmardehei, Mostafa; Alinejad, Faranak; Ansari, Fereshteh; Bahramian, Mahnaz; Barati, Mitra

    2016-01-01

    Background and Objectives: Infection is the most common cause of death among burnt patients and infection control decrease the rate of mortality. The use of sticky mat can control contamination by preventing the entrance microorganisms into the hospital wards. This study was designed to evaluate the sticky mats effect in reduction of microorganism’s entry by personnel shoes to burn intensive care unit (BICU). Materials and Methods: This is a simple cross sectional study. We tested outer soles of personnel’s shoes with swap and cultured them before and after sticky mat contact in the entrance of BICU. Results were analyzed with IBM SPSS version 22 software. McNemar and Wilcoxon Signed Ranks tests were used. Results: We analyzed 60 outer soles of the shoes before and after contact with sticky mats. Coagulase negative Staphylococci, Gram positive bacilli, Staphylococcus aureus, Aspergillus fumigatus, Pseudomonas aeruginosa and Acinetobacter baumannii were isolated before contact from 57 (95%), 32 (53%), 4 (6.7%) and 3 (5%) cases, respectively. Coagulase negative Staphylococci, Gram positive bacilli, Staphylococcus aureus, Aspergillus fumigatus, Pseudomonas aeruginosa were isolated after contact from 36 (60%), 30 (50%), 16 (26.6%), 2 (3.3%) and 3 (5%) cases, respectively. No Acinetobacter was isolated after contact with sticky mat. Total isolated colonies before and after contact with sticky mats were 2573 and 830, respectively. There were significant statistically differences between the colony counts of coagulase ngative staphylococci, Gram positive bacilli, and Staphylococci aureus before and after contact with sticky mats (P. < 0.001). Conclusion: Regarding to statistical analysis, the effect of mat in removing the microorganisms was 56%. It confirms the effectiveness of sticky mat controlling the infection and reducing the amount of hospital contamination. PMID:27928489

  18. qPCR analysis of carbon, nitrogen, and arsenic cycling in Zetaproteobacteria-dominated microbial mats

    NASA Astrophysics Data System (ADS)

    Jesser, K. J.; Fullerton, H.; Hilton, T. S.; Kimber, J.; Hager, K.; Moyer, C. L.

    2013-12-01

    The recently discovered Zetaproteobacteria represent a novel class of Proteobacteria which oxidize Fe(II) to Fe(III) to fix CO2 at hydrothermal vents. Zetaproteobacteria were first discovered at Lo'ihi Seamount, located 35 km southeast of the big island of Hawai'i and characterized by low-temperature diffuse hydrothermal vents. The hydrothermal vents at Lo'ihi are surrounded by luxuriant iron-rich microbial mats dominated by Zetaproteobacteria. We aim to use real-time quantitative PCR (qPCR) to quantify functional genes associated with the microbial carbon, nitrogen, and arsenic cycles in complex Zetaproteobacteria- dominated iron mat communities. Unique qPCR primer sets have been developed based on Illumina next-generation sequence data from an iron mat collected in 2009 at Lo'ihi. These primers target the sequences for arsenate reductase and nitrite reductase, genes associated with arsenic detoxification and denitrification, respectively. Additionally, we are utilizing published primer sets to quantify genes associated with autotrophic carbon and nitrogen fixation pathways. Genomic DNA was isolated from microbial mats at multiple vent sites with varying temperatures and fluid flow during our 2013 expedition to Lo'ihi. The qPCR data for these samples can be used to draw correlations among fine scale mat structures and nutrient cycling processes across diverse mat morphologies, as previous research has identified unique microbial communities and metabolic strategies associated with distinct mat morphologies. This work will enable us to better identify samples for further molecular analysis, and may provide insights into the evolutionary history and metabolic functionality of various mat morphotypes. We hypothesize that Zetaproteobacteria act as ecosystem engineers, driving the structure and function of iron mat ecosystems.

  19. The type of mat (Contact vs. Photocell) affects vertical jump height estimated from flight time.

    PubMed

    García-López, Juan; Morante, Juan C; Ogueta-Alday, Ana; Rodríguez-Marroyo, Jose A

    2013-04-01

    The purposes of this study were to analyze the validity and reliability of 2 photocell mats and to probe the possible influence of the type of mat (contact vs. photocell) on vertical jump height estimated from flight time. In 2 separate studies, 89 and 92 physical students performed 3 countermovement jumps that were simultaneously registered by a Force Plate (gold standard method), 2 photocell mats (SportJump System Pro and ErgoJump Plus), and a contact mat (SportJump-v1.0). The first study showed that the 2 photocell mats underestimated the vertical jump height (1.3 ± 0.2 cm and 5.9 ± 5.2 cm, respectively), but only SportJump System Pro showed a high correlation with the Force Plate (r = 0.999 and 0.676, respectively) and good intraday reliability (coefficient of variation = 2.98 and 15.94%, intraclass correlation coefficients = 0.95-0.97 and 0.45-0.57, respectively). The second study demonstrated a strong correlation (r = 0.994) between the 2 technologies (contact vs. photocell mats) with differences in vertical jump height of 2.0 ± 0.8 cm (95% confidence interval = 1.9-2.1 cm), which depended on both flight time and subjects' body mass. In conclusion, SportJump System Pro was a valid and reliable device. The new devices to measure vertical jump height from flight time should be validated. The type of mat (contact vs. photocell) affected approximately 6% the vertical jump height (approximately 2 cm in this study), which should be considered in further studies. The use of validated photocell mats instead of the contact mats was recommended.

  20. Glass matrix armor

    DOEpatents

    Calkins, Noel C.

    1991-01-01

    An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.