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Sample records for influence melt rate

  1. SLUDGE MASS REDUCTION: PRIMARY COMPOSITIONAL FACTORS THAT INFLUENCE MELT RATE FOR FUTURE SLUDGE BATCH PROJECTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Newell, J; Miller, D; Stone, M; Pickenheim, B

    2008-08-28

    The Savannah River National Laboratory (SRNL) was tasked to provide an assessment of the downstream impacts to the Defense Waste Processing Facility (DWPF) of decisions regarding the implementation of Al-dissolution to support sludge mass reduction and processing. Based on future sludge batch compositional projections from the Liquid Waste Organization's (LWO) sludge batch plan, assessments have been made with respect to the ability to maintain comparable projected operating windows for sludges with and without Al-dissolution. As part of that previous assessment, candidate frits were identified to provide insight into melt rate for average sludge batches representing with and without Al-dissolution flowsheets. Initial melt rate studies using the melt rate furnace (MRF) were performed using five frits each for Cluster 2 and Cluster 4 compositions representing average without and with Al-dissolution. It was determined, however, that the REDOX endpoint (Fe{sup 2+}/{Sigma}Fe for the glass) for Clusters 2 and 4 resulted in an overly oxidized feed which negatively affected the initial melt rate tests. After the sludge was adjusted to a more reduced state, additional testing was performed with frits that contained both high and low concentrations of sodium and boron oxides. These frits were selected strictly based on the ability to ascertain compositional trends in melt rate and did not necessarily apply to any acceptability criteria for DWPF processing. The melt rate data are in general agreement with historical trends observed at SRNL and during processing of SB3 (Sludge Batch 3)and SB4 in DWPF. When MAR acceptability criteria were applied, Frit 510 was seen to have the highest melt rate at 0.67 in/hr for Cluster 2 (without Al-dissolution), which is compositionally similar to SB4. For Cluster 4 (with Al-dissolution), which is compositionally similar to SB3, Frit 418 had the highest melt rate at 0.63 in/hr. Based on this data, there appears to be a slight advantage

  2. Influences of gas flow rates on melting of particles of HVOF sprayed CoCrW coating and coating properties

    Institute of Scientific and Technical Information of China (English)

    YANG Zhongyuan

    2004-01-01

    This paper discussed influences of flow rates of O2, C3H8, and compressed air on the melting degree of particles during HVOF (high velocity oxy-fuel) sprayed CoCrW coating. The O2 flow rate has the maximal effect on the melting of particles, the C3H8 flow rate has the second, and the compressed air flow rate has the minimal effect. The bond strength of the HVOF sprayed CoCrW coating is over 54 MPa. The porosity ratio of the HVOF sprayed CoCrW coating after optimization of gas flow rates is less than 2%. The average microhardness of the coating is up to HV0.1 545. The oxidation amount per unit area of the HVOF sprayed CoCrW coating increases with the holding time increasing at 800°C. In the same way,the oxidation amount of the coating increases as the temperature increases. Particularly, the oxidation of the coating drastically increases over 850°C.

  3. Melt Rate Improvement for DWPF MB3: Melt Rate Furnace Testing

    Energy Technology Data Exchange (ETDEWEB)

    Stone, M.E.

    2001-07-24

    The Defense Waste Processing Facility (DWPF) would like to increase its canister production rate. The goal of this study is to improve the melt rate in DWPF specifically for Macrobatch 3. However, the knowledge gained may result in improved melting efficiencies translating to future DWPF macrobatches and in higher throughput for other Department of Energy's (DOE) melters. Increased melting efficiencies decrease overall operational costs by reducing the immobilization campaign time for a particular waste stream. For melt rate limited systems, a small increase in melting efficiency translates into significant hard dollar savings by reducing life cycle operational costs.

  4. A slow cooling rate of indomethacin melt spatially confined in microcontainers increases the physical stability of the amorphous drug without influencing its biorelevant dissolution behaviour

    DEFF Research Database (Denmark)

    Nielsen, Line Hagner; Keller, Stephan Sylvest; Boisen, Anja;

    2013-01-01

    Amorphous indomethacin was prepared by melting the γ-form of indomethacin, spatially confined within microcontainers (inner diameter of 223 μm), followed by cooling of the melt at a rate of 14, 23 or 36 K/min. The physical stability of the amorphous indomethacin within microcontainers was investi......Amorphous indomethacin was prepared by melting the γ-form of indomethacin, spatially confined within microcontainers (inner diameter of 223 μm), followed by cooling of the melt at a rate of 14, 23 or 36 K/min. The physical stability of the amorphous indomethacin within microcontainers....../min, whereas cracks and an uneven surface were observed when cooling at rates of 23 and 36 K/min. The uneven surface is hypothesised to be the main reason for the lower physical stability, as the cracks could act as nucleation sites for crystal growth. The rate of cooling was not seen to have any effect...

  5. Laser melting treatment of Ni-P surface alloys on mild steel. Influence of initial coating thickness and laser scanning rate

    Directory of Open Access Journals (Sweden)

    García-Alonso, M. C.

    1997-08-01

    Full Text Available Different thickness Ni-P coatings deposited on mild steel are submitted to laser surface melting at different scanning rates. The microstructure of the alloys is characterized by optical and scanning electron microscopy and microprobe analysis. It is shown that both the initial coating thickness and the laser scanning rate have an influence on the shape, extent and size of the different structures resulting from the solidification process. Thus, when the laser scanning rate increases a progressive refinement of the structure takes place that could even totally block the dendritic growth produced during solidification for a high initial coating thickness.

    Recubrimientos de Ni-P, con distinto espesor, depositados sobre un acero microaleado fueron tratados con láser a diferentes velocidades de barrido. La microestructura, tanto del recubrimiento como del acero base, ha sido caracterizada por microscopía óptica y electrónica y por microanálisis. En el proceso de solidificación se han obtenido distintas estructuras que varían en cuanto a la forma, extensión y tamaño dependiendo del espesor inicial de recubrimiento y de la velocidad de barrido del haz láser. A medida que la velocidad del haz aumenta, se produce un refinamiento progresivo de la microestructura dendrítica y, en casos extremos de alto espesor de recubrimiento y velocidades grandes, este crecimiento dendrítico se bloquea.

  6. Ice cream structural elements that affect melting rate and hardness.

    Science.gov (United States)

    Muse, M R; Hartel, R W

    2004-01-01

    Statistical models were developed to reveal which structural elements of ice cream affect melting rate and hardness. Ice creams were frozen in a batch freezer with three types of sweetener, three levels of the emulsifier polysorbate 80, and two different draw temperatures to produce ice creams with a range of microstructures. Ice cream mixes were analyzed for viscosity, and finished ice creams were analyzed for air cell and ice crystal size, overrun, and fat destabilization. The ice phase volume of each ice cream were calculated based on the freezing point of the mix. Melting rate and hardness of each hardened ice cream was measured and correlated with the structural attributes by using analysis of variance and multiple linear regression. Fat destabilization, ice crystal size, and the consistency coefficient of the mix were found to affect the melting rate of ice cream, whereas hardness was influenced by ice phase volume, ice crystal size, overrun, fat destabilization, and the rheological properties of the mix.

  7. MELT RATE FURNACE TESTING FOR SLUDGE BATCH 5 FRIT OPTIMIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D; Fox, K; Pickenheim, B; Stone, M

    2008-10-03

    Savannah River National Laboratory (SRNL) was requested to provide the Defense Waste Processing Facility (DWPF) with a frit composition for Sludge Batch 5 (SB5) to optimize processing. A series of experiments were designed for testing in the Melt Rate Furnace (MRF). This dry fed tool can be used to quickly determine relative melt rates for a large number of candidate frit compositions and lead to a selection for further testing. Simulated Sludge Receipt and Adjustment Tank (SRAT) product was made according to the most recent SB5 sludge projections and a series of tests were conducted with frits that covered a range of boron and alkali ratios. Several frits with relatively large projected operating windows indicated melt rates that would not severely impact production. As seen with previous MRF testing, increasing the boron concentration had positive impacts on melt rate on the SB5 system. However, there appears to be maximum values for both boron and sodium above which the there is a negative effect on melt rate. Based on these data and compositional trends, Frit 418 and a specially designed frit (Frit 550) have been selected for additional melt rate testing. Frit 418 and Frit 550 will be run in the Slurry Fed Melt Rate Furnace (SMRF), which is capable of distinguishing rheological properties not detected by the MRF. Frit 418 will be used initially for SB5 processing in DWPF (given its robustness to compositional uncertainty). The Frit 418-SB5 system will provide a baseline from which potential melt rate advantages of Frit 550 can be gauged. The data from SMRF testing will be used to determine whether Frit 550 should be recommended for implementation in DWPF.

  8. Crust behavior and erosion rate prediction of EPR sacrificial material impinged by core melt jet

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gen; Liu, Ming, E-mail: ming.liu@mail.xjtu.edu.cn; Wang, Jinshi; Chong, Daotong; Yan, Junjie

    2017-04-01

    Highlights: • A numerical code was developed to analyze melt jet-concrete interaction in the frame of MPS method. • Crust and ablated concrete layer at UO{sub 2}-ZrO{sub 2} melt and concrete interface periodically developed and collapsed. • Concrete surface temperature fluctuated around a low temperature and ablation temperature. • Concrete erosion by Fe-Zr melt jet was significantly faster than that by UO{sub 2}-ZrO{sub 2} melt jet. - Abstract: Sacrificial material is a special ferro-siliceous concrete, designed in the ex-vessel core melt stabilization system of European Pressurized water Reactor (EPR). Given a localized break of RPV lower head, the melt directly impinges onto the dry concrete in form of compact jet. The concrete erosion behavior influences the failure of melt plug, and further affects melt spreading. In this study, a numerical code was developed in the frame of Moving Particle Semi-implicit (MPS) method, to analyze the crust behavior and erosion rate of sacrificial concrete, impinged by prototypic melt jet. In validation of numerical modeling, the time-dependent erosion depth and erosion configuration matched well with the experimental data. Sensitivity study of sacrificial concrete erosion indicates that the crust and ablated concrete layer presented at UO{sub 2}-ZrO{sub 2} melt and concrete interface, whereas no crust could be found in the interaction of Fe-Zr melt with concrete. The crust went through stabilization-fracture-reformation periodic process, accompanied with accumulating and collapsing of molten concrete layer. The concrete surface temperature fluctuated around a low temperature and ablation temperature. It increased as the concrete surface layer was heated to melting, and dropped down when the cold concrete was revealed. The erosion progression was fast in the conditions of small jet diameter and large concrete inclination angle, and it was significantly faster in the erosion by metallic melt jet than by oxidic melt jet.

  9. Effect of cooling rate on crystallization in an aluminophosphosilicate melt

    DEFF Research Database (Denmark)

    Liu, S. J.; Zhang, Yanfei; Yue, Yuanzheng

    2011-01-01

    The effect of cooling rate on spontaneous crystallization behavior of an alumino-phospho-silicate melt is studied by means of differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and viscometry. The cooling rates of 160, 2100 and 12000 K/s are attained by subjecting...

  10. Effect of cooling rate on crystallization in an aluminophosphosilicate melt

    DEFF Research Database (Denmark)

    Liu, S. J.; Zhang, Yanfei; Yue, Yuanzheng

    2011-01-01

    The effect of cooling rate on spontaneous crystallization behavior of an alumino-phospho-silicate melt is studied by means of differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and viscometry. The cooling rates of 160, 2100 and 12000 K/s are attained by subjecting...

  11. Influence of Grain Boundary on Melting

    Institute of Scientific and Technical Information of China (English)

    王暾; 周富信; 刘曰武

    2001-01-01

    The temperature behaviour of an Al bicrystal with surfaces consisting of (110) and (111) crystals is simulated using molecular dynamics. The result shows that the (110) crystal losses its crystalline order at 820K, whereas the disorder does not propagate through the (111) crystal at this temperature. Instead, some disordered atoms are recrystallized into the (111) crystal and the initial grain boundary changes into a stable order-disorder interface. Thus, it was discovered that at a temperature near its melting point, the (111) crystal grew and obstructed the propagation of disorder. Such an obstruction is helpfulfor understanding melting.

  12. Analysis of Water Recovery Rate from the Heat Melt Compactor

    Science.gov (United States)

    Balasubramaniam, R.; Hegde, U.; Gokoglu, S.

    2013-01-01

    any remaining free water in the trash by evaporation. The temperature settings of the heated surfaces are usually kept above the saturation temperature of water but below the melting temperature of the plastic in the waste during this step to avoid any encapsulation of wet trash which would reduce the amount of recovered water by blocking the vapor escape. In this paper, we analyze the water recovery rate during Phase B where the trash is heated and water leaves the waste chamber as vapor, for operation of the HMC in reduced gravity. We pursue a quasi-one-dimensional model with and without sidewall heating to determine the water recovery rate and the trash drying time. The influences of the trash thermal properties, the amount of water loading, and the distribution of the water in the trash on the water recovery rates are determined.

  13. Melt Rate Improvement for DWPF MB3: Summary and Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.P.

    2001-07-11

    The objective for this task is to understand and apply the control of glass batch chemistry (frit composition) and/or changes in chemical processing strategies to improve the overall melting process for Macrobatch 3 (MB3) (Defense Waste Processing Facility (DWPF) sludge-only processing). For melt rate limited systems, a small increase in melting efficiency translates into substantial savings by reducing operational costs without compromising the quality of the final waste product. This report summarizes the key information collected during the FY01 melt-rate testing completed to support the conclusion that switching from Frit 200, the frit currently used to prepare all the glass produced in radioactive processing, to Frit 320 should improve the melt rate during processing of DWPF MB3 sludge (Note: MB3 is referred to as Sludge Batch 2 in the High-Level Waste System Plan). The report also includes recommendations that should be addressed prior to implementation of the new frit and future research that should be completed to further improve melt rate. No analysis has been completed to determine if Frit 320 can be used in processing of other sludge macrobatches. The testing in this report is based on dried-slurry testing of a MB3 melter feed prepared from nonradioactive simulants. Additional testing, particularly with a melter feed slurry and actual waste, would be required before implementing the new frit in DWPF, and a variability study would also be necessary. The work to date, at most, provides relative data until actual melter data can be obtained and compared.

  14. Influence of Ultrasonic Melt Treatment and Cooling Rates on the Microstructural Development and Elevated Temperature Mechanical Properties of a Hypereutectic Al-18Si-4Cu-3Ni Piston Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jea-Hee; Cho, Young-Hee; Jung, Jae-Gil; Lee, Jung-Moo [Korea Institute of Materials Science (KIMS), Changwon (Korea, Republic of); Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2017-06-15

    The influence of ultrasonic melt treatment (UST) combined with a change in cooling rates on the microstructure and elevated temperature mechanical properties of a hypereutectic Al-18Si-4Cu-3Ni piston alloy was investigated. Microstructural observation confirmed that UST effectively refined the sizes of primary Si and intermetallic compounds (e.g. ε-Al{sub 3}Ni) while promoting their homogeneous distribution. Besides the refinement of the constituent phases, the size of the dendrite arm spacing (DAS), which was hardly affected by UST, significantly deceased with increasing cooling rates. The refinement of the solidification structure in the alloy achieved through both UST and increased cooling rates resulted in an improvement in tensile properties, ultimate tensile strength and elongation in particular, after T5 heat treatment followed by overaging at 350 ℃. However, the elevated temperature yield strength of the alloy was not associated with the refinement, but was rather correlated with the 3-D interconnectivity, morphology and volume fraction of the primary Si.

  15. DETERMINATION OF HLW GLASS MELT RATE USING X-RAY COMPUTED TOMOGRAPHY

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.; Miller, D.; Immel, D.

    2011-10-06

    The purpose of the high-level waste (HLW) glass melt rate study is two-fold: (1) to gain a better understanding of the impact of feed chemistry on melt rate through bench-scale testing, and (2) to develop a predictive tool for melt rate in support of the on-going frit development efforts for the Defense Waste Processing Facility (DWPF). In particular, the focus is on predicting relative melt rates, not the absolute melt rates, of various HLW glass formulations solely based on feed chemistry, i.e., the chemistry of both waste and glass-forming frit for DWPF. Critical to the successful melt rate modeling is the accurate determination of the melting rates of various HLW glass formulations. The baseline procedure being used at the Savannah River National Laboratory (SRNL) is to; (1) heat a 4 inch-diameter stainless steel beaker containing a mixture of dried sludge and frit in a furnace for a preset period of time, (2) section the cooled beaker along its diameter, and (3) measure the average glass height across the sectioned face using a ruler. As illustrated in Figure 1-1, the glass height is measured for each of the 16 horizontal segments up to the red lines where relatively large-sized bubbles begin to appear. The linear melt rate (LMR) is determined as the average of all 16 glass height readings divided by the time during which the sample was kept in the furnace. This 'visual' method has proved useful in identifying melting accelerants such as alkalis and sulfate and further ranking the relative melt rates of candidate frits for a given sludge batch. However, one of the inherent technical difficulties of this method is to determine the glass height in the presence of numerous gas bubbles of varying sizes, which is prevalent especially for the higher-waste-loading glasses. That is, how the red lines are drawn in Figure 1-1 can be subjective and, therefore, may influence the resulting melt rates significantly. For example, if the red lines are drawn too low

  16. Influence Of Process Conditions On Melt Blown Web Structure. Part IV - Fiber Diameter

    Directory of Open Access Journals (Sweden)

    Randall R. Bresee

    2006-08-01

    Full Text Available We are continuing an effort to quantitatively measure the influence of processing variables on the structure of polypropylene melt blown webs. In this paper, we report experimental measurements of the influence of die-to-collector distance, primary airflow rate, die temperature, collector speed and resin throughput rate on the diameter of fibers in fully-formed webs. This enabled us to quantitatively compare the influence of these processing variables on fiber diameter as well as achieve greater understanding of the melt blowing process.

  17. Influence of processing parameters on laser penetration depth and melting/re-melting densification during selective laser melting of aluminum alloy

    Science.gov (United States)

    Yu, Guanqun; Gu, Dongdong; Dai, Donghua; Xia, Mujian; Ma, Chenglong; Chang, Kun

    2016-10-01

    A three-dimensional mesoscopic model, considering the powder-to-solid transition, motion of gas bubbles within molten pool and the effect of surface tension, has been established in order to investigate the evolution rule of pores and re-melting densification mechanism during selective laser melting of AlSi10Mg. The results indicated that re-melting phenomenon of previous fabricated layer induced by laser melting of current powder layer played a crucial role on the increase in densification rate. During the re-melting process, the trapped gas pores in previous layer rose up swiftly and came to the surface consequently, resulting in remarkably elevated densification in previous layer. The influences of laser scan speed on the single-track morphology, types of pores and laser penetration depth have also been studied. It showed that the maximum re-melting depth (31 µm) was attained, and meanwhile, pores left in preceding layer got eliminated completely due to the mass transfer within molten pool, when an appropriate laser scan speed (150 mm/s) was applied. In this case, reasonable laser energy per unit length and irradiation time tended to enhance the laser penetration depth for powder bed and decrease the porosity in as-fabricated layer. A series of experimental study were performed to verify the reliability of the above mesoscopic simulation, including the surface topography of single track and the types of pores. The redistribution of bubbles between the adjacent layers as well as the localized re-melting densification, which were observed from the longitudinal section of samples, was in good agreement with simulation results.

  18. DETERMINATION OF HLW GLASS MELT RATE USING X-RAY COMPUTED TOMOGRAPHY

    Energy Technology Data Exchange (ETDEWEB)

    Choi, A.; Miller, D.; Immel, D.

    2011-10-06

    The purpose of the high-level waste (HLW) glass melt rate study is two-fold: (1) to gain a better understanding of the impact of feed chemistry on melt rate through bench-scale testing, and (2) to develop a predictive tool for melt rate in support of the on-going frit development efforts for the Defense Waste Processing Facility (DWPF). In particular, the focus is on predicting relative melt rates, not the absolute melt rates, of various HLW glass formulations solely based on feed chemistry, i.e., the chemistry of both waste and glass-forming frit for DWPF. Critical to the successful melt rate modeling is the accurate determination of the melting rates of various HLW glass formulations. The baseline procedure being used at the Savannah River National Laboratory (SRNL) is to; (1) heat a 4 inch-diameter stainless steel beaker containing a mixture of dried sludge and frit in a furnace for a preset period of time, (2) section the cooled beaker along its diameter, and (3) measure the average glass height across the sectioned face using a ruler. As illustrated in Figure 1-1, the glass height is measured for each of the 16 horizontal segments up to the red lines where relatively large-sized bubbles begin to appear. The linear melt rate (LMR) is determined as the average of all 16 glass height readings divided by the time during which the sample was kept in the furnace. This 'visual' method has proved useful in identifying melting accelerants such as alkalis and sulfate and further ranking the relative melt rates of candidate frits for a given sludge batch. However, one of the inherent technical difficulties of this method is to determine the glass height in the presence of numerous gas bubbles of varying sizes, which is prevalent especially for the higher-waste-loading glasses. That is, how the red lines are drawn in Figure 1-1 can be subjective and, therefore, may influence the resulting melt rates significantly. For example, if the red lines are drawn too low

  19. Influence of melt mixer on injection molding of thermoset elastomers

    Science.gov (United States)

    Rochman, Arif; Zahra, Keith

    2016-10-01

    One of the drawbacks in injection molding is that the plasticizing screw is short such that polymers having high concentrations of additives, such as thermoset elastomers, might not mix homogeneously within the short period of time during the plasticizing stage. In this study, various melt mixers inside the nozzle chamber, together forming a mixing nozzle, were developed. Three different materials were investigated, namely nitrile butadiene rubber (NBR), ethylene propylene-diene monomer (EPDM) and fluorocarbon (FKM). The use of these melt mixers resulted in better homogeneity and properties of the molded parts despite a curing time reduction of 10 s. This was due to the increase in mixing and shearing introduced a higher rate of crosslinking formation in the molded parts.

  20. Melt rate sensitivities underneath Pine Island Ice Shelf derived from an adjoint general circulation model

    OpenAIRE

    Losch, Martin; Heimbach, Patrick

    2012-01-01

    Increased melt rates under floating ice shelves around Antarctica have been suggested as a dominant cause for observed acceleration of marine ice sheets that feed these ice shelves. The associated melt rates are difficult to observe directly. We present first steps towards estimating the melt rates underneath floating ice shelves from accessible hydrography data and optimal control methods. We address to which extent ocean hydrographic observations away from the ice-ocean boundary can be...

  1. Calving fluxes and basal melt rates of Antarctic ice shelves.

    Science.gov (United States)

    Depoorter, M A; Bamber, J L; Griggs, J A; Lenaerts, J T M; Ligtenberg, S R M; van den Broeke, M R; Moholdt, G

    2013-10-03

    Iceberg calving has been assumed to be the dominant cause of mass loss for the Antarctic ice sheet, with previous estimates of the calving flux exceeding 2,000 gigatonnes per year. More recently, the importance of melting by the ocean has been demonstrated close to the grounding line and near the calving front. So far, however, no study has reliably quantified the calving flux and the basal mass balance (the balance between accretion and ablation at the ice-shelf base) for the whole of Antarctica. The distribution of fresh water in the Southern Ocean and its partitioning between the liquid and solid phases is therefore poorly constrained. Here we estimate the mass balance components for all ice shelves in Antarctica, using satellite measurements of calving flux and grounding-line flux, modelled ice-shelf snow accumulation rates and a regional scaling that accounts for unsurveyed areas. We obtain a total calving flux of 1,321 ± 144 gigatonnes per year and a total basal mass balance of -1,454 ± 174 gigatonnes per year. This means that about half of the ice-sheet surface mass gain is lost through oceanic erosion before reaching the ice front, and the calving flux is about 34 per cent less than previous estimates derived from iceberg tracking. In addition, the fraction of mass loss due to basal processes varies from about 10 to 90 per cent between ice shelves. We find a significant positive correlation between basal mass loss and surface elevation change for ice shelves experiencing surface lowering and enhanced discharge. We suggest that basal mass loss is a valuable metric for predicting future ice-shelf vulnerability to oceanic forcing.

  2. Influence of starting material on the degassing behavior of trachytic and phonolitic melts

    Science.gov (United States)

    Preuss, Oliver; Marxer, Holger; Nowak, Marcus

    2015-04-01

    The dynamic magmatic processes beneath volcanic systems, occurring during magma ascent, cannot be observed directly in nature. Simulation of magma ascent in the lab realized by continuous decompression (CD) of a volatile containing melt is essential to understand these processes that may lead to potentially catastrophic eruptions threatening millions of people in highly populated areas like Naples located between the Campi Flegrei Volcanic Field and the Monte Somma-Vesuvio strato-volcano. In this project, experimental simulations of Campanian Ignimbrite (CI) magma ascent will give insight to the mechanisms of the CI super eruption, thus providing tools for volcanic hazard assessment at the high risk Campanian Volcanic District and other comparable volcanic systems. Additionally, comparable experiments with the same conditions using the 'white pumice' composition of the catastrophic Vesuvius AD 79 (VAD79) eruption, have been conducted. So far, the experiments were performed in an internally heated argon pressure vessel coupled with a high-pressure low-flow metering valve and a piezoelectric nano-positioning system using a starting pressure of 200 MPa, H2O content of about 5 wt% and two different decompression rates (0.024 and 0.17 MPa/s) at a superliquidus temperature of 1050 ° C to ensure a crystal free melt and a homogeneous bubble nucleation. Experiments were conducted with both, glass powder and cylinders, subsequently decompressed to 75 and 100 MPa and rapidly quenched. Beside the results that e.g. decompression rate, volatile content, fluid solubility and target pressure affect the degassing behavior of the melt, the influence of the starting material on the degassing processes is significant. Analyses of BSE- and transmitted light microscopy images revealed a different degassing behavior of glass cylinder experiments compared to powders. Nitrogen has a very low solubility in hydrous silicate melts, supporting our suggestion that preexisting nitrogen rich

  3. The influence of partial melting and melt migration on the rheology of the continental crust

    Science.gov (United States)

    Cavalcante, Geane Carolina G.; Viegas, Gustavo; Archanjo, Carlos José; da Silva, Marcos Egydio

    2016-11-01

    The presence of melt during deformation produces a drastic change in the rheological behavior of the continental crust; rock strength is decreased even for melt fractions as low as ∼7%. At pressure/temperature conditions typical of the middle to lower crust, melt-bearing systems may play a critical role in the process of strain localization and in the overall strength of the continental lithosphere. In this contribution we focus on the role and dynamics of melt flow in two different mid-crustal settings formed during the Brasiliano orogeny: (i) a large-scale anatectic layer in an orthogonal collision belt, represented by the Carlos Chagas anatexite in southeastern Brazil, and (ii) a strike-slip setting, in which the Espinho Branco anatexite in the Patos shear zone (northeast Brazil) serves as an analogue. Both settings, located in eastern Brazil, are part of the Neoproterozoic tectonics that resulted in widespread partial melting, shear zone development and the exhumation of middle to lower crustal layers. These layers consist of compositionally heterogeneous anatexites, with variable former melt fractions and leucosome structures. The leucosomes usually form thick interconnected networks of magma that reflect a high melt content (>30%) during deformation. From a comparison of previous work based on detailed petrostructural and AMS studies of the anatexites exposed in these areas, we discuss the rheological implications caused by the accumulation of a large volume of melt "trapped" in mid-crustal levels, and by the efficient melt extraction along steep shear zones. Our analyses suggest that rocks undergoing partial melting along shear settings exhibit layers with contrasting competence, implying successive periods of weakening and strengthening. In contrast, regions where a large amount of magma accumulates lack clear evidence of competence contrast between layers, indicating that they experienced only one major stage of dramatic strength drop. This comparative

  4. Impact of fine debris on ice melt rates at Russell Glacier, central-west Greenland

    Science.gov (United States)

    Carr, Rachel; Linighan, James; Cumming, Alex M. J.

    2017-04-01

    Losses from the Greenland Ice Sheet (GrIS) have increased sharply in recent years, due to accelerated glacier discharge and increased surface melting. In 2012, 99% of the Greenland ice sheet experienced melt, which was exceptional on centennial timescales, but is expected to occur frequently in the future, as climate warms. Ice albedo is a primary control on melt rates and remotely sensed data shows that the GrIS has darkened substantial in recent decades, due to both inorganic and biological material. This has been particularly marked in south- and central-west Greenland and can lead to the development of positive feedbacks. Consequently, it is important to understand the relationship between melt and surface albedo on the GrIS. Here we use a combination of satellite remote sensing and field data to assess the impact of fine debris on melt rates at Russell Glacier, central-west Greenland. Our field data demonstrate that areas with a greater percentage coverage of fine, largely inorganic debris experienced higher melt rates than in areas with a sparse coverage. However, the relationship between melt and debris cover was highly spatially variable. Furthermore, the debris cover evolved substantially over time and we saw marked changes over a period of a few days. Using ASTER imagery, we show that the spatial extent of debris has expanded markedly in this section of the GrIS during the last decade, which could substantially accelerate melting. However, the complex and variable relationship between debris cover and melt rates highlights the need for further research, in order to accurately forecast its impact on GrIS melt rates.

  5. Melt transport rates in heterogeneous mantle beneath mid-ocean ridges

    CERN Document Server

    Weatherley, Samuel M

    2015-01-01

    Recent insights to melt migration beneath ridges suggest that channelized flow is a consequence of melting of a heterogeneous mantle, and that spreading rate modulates the dynamics of the localized flow. A corollary of this finding is that both mantle het- erogeneity and spreading rate have implications for the speed and time scale of melt migration. Here, we investigate these implications using numerical models of magma flow in heterogeneous mantle beneath spreading plates. The models predict that a broad distribution of magma flow speeds is characteristic of the sub-ridge mantle. Within the melting region, magmatic flow is fastest in regions of average fusibility; surprisingly, magmas from sources of above-average fusibility travel to the ridge in a longer time. Spreading rate has comparatively simple consequences, mainly resulting in faster segregation speeds at higher spreading rates. The computed time scales are short enough to preserve deep origin 230Th disequilibria and, under favourable parameter regi...

  6. Influence of Melt Feeding Scheme and Casting Parameters During Direct-Chill Casting on Microstructure of an AA7050 Billet

    Science.gov (United States)

    Zhang, L.; Eskin, D. G.; Miroux, A.; Subroto, T.; Katgerman, L.

    2012-12-01

    Direct-chill (DC) casting billets of an AA7050 alloy produced with different melt feeding schemes and casting speeds were examined in order to reveal the effect of these factors on the evolution of microstructure. Experimental results show that grain size is strongly influenced by the casting speed. In addition, the distribution of grain sizes across the billet diameter is mostly determined by melt feeding scheme. Grains tend to coarsen towards the center of a billet cast with the semi-horizontal melt feeding, while upon vertical melt feeding the minimum grain size was observed in the center of the billet. Computer simulations were preformed to reveal sump profiles and flow patterns during casting under different melt feeding schemes and casting speeds. The results show that solidification front and velocity distribution of the melt in the liquid and slurry zones are very different under different melt feeding scheme. The final grain structure and the grain size distribution in a DC casting billet is a result of a combination of fragmentation effects in the slurry zone and the cooling rate in the solidification range.

  7. Effects of locust bean gum and mono- and diglyceride concentrations on particle size and melting rates of ice cream.

    Science.gov (United States)

    Cropper, S L; Kocaoglu-Vurma, N A; Tharp, B W; Harper, W J

    2013-06-01

    The objective of this study was to determine how varying concentrations of the stabilizer, locust bean gum (LBG), and different levels of the emulsifier, mono- and diglycerides (MDGs), influenced fat aggregation and melting characteristics of ice cream. Ice creams were made containing MDGs and LBG singly and in combination at concentrations ranging between 0.0% to 0.14% and 0.0% to 0.23%, respectively. Particle size analysis, conducted on both the mixes and ice cream, and melting rate testing on the ice cream were used to determine fat aggregation. No significant differences (P ice cream mixes. However, higher concentrations of both LBG and MDG in the ice creams resulted in values that were larger than the control. This study also found an increase in the particle size values when MDG levels were held constant and LBG amounts were increased in the ice cream. Ice creams with higher concentrations of MDG and LBG together had the greatest difference in the rate of melting than the control. The melting rate decreased with increasing LBG concentrations at constant MDG levels. These results illustrated that fat aggregation may not only be affected by emulsifiers, but that stabilizers may play a role in contributing to the destabilization of fat globules.

  8. Insignificant influence of the matrix on the melting of incoherently embedded tin and zinc nanoparticles

    Science.gov (United States)

    Shen, L. M.; Hou, H. F.; Yao, C. Y.; Wang, L. W.

    2017-01-01

    For studying the melting point depression of metals, isolated metallic nanoparticles embedded in a matrix are usually prepared by mechanical milling. Al is the main available matrix material. In this work, to explore possible alternative matrices for further investigation of melting, mechanically milled metal-nonmetal systems are developed, namely Sn-LiF, Zn-LiF and Zn-Al2O3. The outcome indicates that different matrices do not have a significantly different influence on the melting of Sn and Zn. Theoretical analyses of both the thermodynamics and kinetics of surface-induced melting may support this experimental finding.

  9. Influence of glycerol on the melting of potato starch

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Soest, J.J.G. van; Bezemer, R.C.; Wit, D. de

    1996-01-01

    The gelatinization and melting of granular and recrystallized starch have been studied in the presence of low and high levels of glycerol or water by differential scanning calorimetry. The gelatinization onset temperature is increased in the presence of glycerol, whereas the excess gelatinization

  10. Influence of glycerol on the melting of potato starch

    NARCIS (Netherlands)

    Soest, van J.J.G.; Bezemer, R.C.; Wit, de D.; Viiegenthart, J.F.G.

    1996-01-01

    The gelatinization and melting of granular and recrystallized starch have been studied in the presence of low and high levels of glycerol or water by differential scanning calorimetry. The gelatinization onset temperature is increased in the presence of glycerol, whereas the excess gelantinization

  11. Laboratory-Scale Melter for Determination of Melting Rate of Waste Glass Feeds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Sang; Schweiger, Michael J.; Buchmiller, William C.; Matyas, Josef

    2012-01-09

    The purpose of this study was to develop the laboratory-scale melter (LSM) as a quick and inexpensive method to determine the processing rate of various waste glass slurry feeds. The LSM uses a 3 or 4 in. diameter-fused quartz crucible with feed and off-gas ports on top. This LSM setup allows cold-cap formation above the molten glass to be directly monitored to obtain a steady-state melting rate of the waste glass feeds. The melting rate data from extensive scaled-melter tests with Hanford Site high-level wastes performed for the Hanford Tank Waste Treatment and Immobilization Plant have been compiled. Preliminary empirical model that expresses the melting rate as a function of bubbling rate and glass yield were developed from the compiled database. The two waste glass feeds with most melter run data were selected for detailed evaluation and model development and for the LSM tests so the melting rates obtained from LSM tests can be compared with those from scaled-melter tests. The present LSM results suggest the LSM setup can be used to determine the glass production rates for the development of new glass compositions or feed makeups that are designed to increase the processing rate of the slurry feeds.

  12. Late stages of high rate tension of aluminum melt: Molecular dynamic simulation

    Science.gov (United States)

    Mayer, Polina N.; Mayer, Alexander E.

    2016-08-01

    With the help of molecular dynamic simulation, we investigate late stages of aluminum melt tension up to the deformation degree of about 10, including a stage of bubble liquid, a foamed melt, and a fragmentation with formation of droplets. Complete fracture of melt is a complex process, which includes nucleation of pores, growth and coalescence of neighboring pores, thinning and breaking of walls between them with the formation of a system of jets, and, finally, breaking of jets into droplets. The transition from the foamed melt to the system of jets and the subsequent fragmentation into droplets occur at the volume fraction of condensed matter considerably smaller than 0.1. The number of pores at the volume fraction of condensed matter about 0.5 and the number of droplets at the final stage of fragmentation are not directly connected with each other. At the same time, both numbers are increased together with the increase in the strain rate and have the same order of magnitude. At the stage of melt with pores, the growth and coalescence of pores are controlled by surface tension, which allows us to construct an analytical estimation for time dependence of the pore average radius. Also, we propose analytical estimations for the mean pressure of melt with pores, which remain negative, and for the work of tension. A few times larger work is spent on the tension of melt with pores if compared with the initial stage of tension near the dynamic strength threshold. The last fact is favorable for the production of the foamed aluminum by means of the high-rate tension of its melt.

  13. Nitric-glycolic flowsheet evaluation with the slurry-fed melt rate furnace

    Energy Technology Data Exchange (ETDEWEB)

    Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Miller, D. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fowley, M. D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Zamecnik, J. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-03-01

    The Savannah River National Laboratory (SRNL) was tasked to support validation of the Defense Waste Processing Facility (DWPF) melter offgas flammability model for the nitric-glycolic (NG) flowsheet. The work supports Deliverable 4 of the DWPF & Saltstone Facility Engineering Technical Task Request (TTR)1 and is supplemental to the Cold Cap Evaluation Furnace (CEF) testing conducted in 2014.2 The Slurry-fed Melt Rate Furnace (SMRF) was selected for the supplemental testing as it requires significantly less resources than the CEF and could provide a tool for more rapid analysis of melter feeds in the future. The SMRF platform has been used previously to evaluate melt rate behavior of DWPF glasses, but was modified to accommodate analysis of the offgas stream. Additionally, the Melt Rate Furnace (MRF) and Quartz Melt Rate Furnace (QMRF) were utilized for evaluations. MRF data was used exclusively for melt behavior observations and REDuction/OXidation (REDOX) prediction comparisons and will be briefly discussed in conjunction with its support of the SMRF testing. The QMRF was operated similarly to the SMRF for the same TTR task, but will be discussed in a separate future report. The overall objectives of the SMRF testing were to; 1) Evaluate the efficacy of the SMRF as a platform for steady state melter testing with continuous feeding and offgas analysis; and 2) Generate supplemental melter offgas flammability data to support the melter offgas flammability modelling effort for DWPF implementation of the NG flowsheet.

  14. SUMMARY OF 2010 DOE EM INTERNATIONAL PROGRAM STUDIES OF WASTE GLASS MELT RATE ENHANCEMENT

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Marra, J.

    2011-01-19

    A collaborative study has been established under the U.S. Department of Energy (DOE) Office of Environmental Management International Program between the Savannah River National Laboratory (SRNL) and the V. G. Khlopin Radium Institute (KRI) in St. Petersburg, Russia, to investigate potential improvements in melt rate via chemical additions to the glass frit. Researchers at KRI suggested a methodology for selecting frit additives based on empirical coefficients for optimization of glass melting available in the Russian literature. Using these coefficients, KRI identified B{sub 2}O{sub 3}, CuO, and MnO as frit additives that were likely to improve melt rate without having adverse effects on crystallization of the glass or its chemical durability. The results of the melt rate testing in the SMK melter showed that the slurry feed rate (used as a gauge of melt rate) could be significantly increased when MnO or CuO were added to Frit 550 with the SMR-2 sludge. The feed rates increased by about 27% when MnO was added to the frit and by about 26% when CuO was added to the frit, as compared to earlier results for Frit 550 alone. The impact of adding additional B{sub 2}O{sub 3} to the frit was minor when added with CuO. The additional B{sub 2}O{sub 3} showed a more significant, 39% improvement in melt rate when added with MnO. The additional B{sub 2}O{sub 3} also reduced the viscosity of the glasses during pouring. Samples of the glasses from the melt rate testing characterized at SRNL showed that there were no significant impacts on crystallization of the glasses. All of the glasses had very good chemical durability. Chemical composition measurements showed that the frit additives were present in concentrations below the targeted values in some of the glasses. Therefore, it is possible that higher concentrations of these additives may further improve melt rate, although the impacts of higher concentrations of these components on crystallization and durability would need to

  15. PRELIMINARY FRIT DEVELOPMENT AND MELT RATE TESTING FOR SLUDGE BATCH 6 (SB6)

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Miller, D.; Edwards, T.

    2009-07-21

    The Liquid Waste Organization (LWO) provided the Savannah River National Laboratory (SRNL) with a Sludge Batch 6 (SB6) composition projection in March 2009. Based on this projection, frit development efforts were undertaken to gain insight into compositional effects on the predicted and measured properties of the glass waste form and to gain insight into frit components that may lead to improved melt rate for SB6-like compositions. A series of Sludge Batch 6 (SB6) based glasses was selected, fabricated and characterized in this study to better understand the ability of frit compositions to accommodate uncertainty in the projected SB6 composition. Acceptable glasses (compositions where the Product Composition Control System (PCCS) Measurement Acceptability Region (MAR) predicted acceptable properties, good chemical durability was measured, and no detrimental nepheline crystallization was observed) can be made using Frit 418 with SB6 over a range of Na{sub 2}O and Al{sub 2}O{sub 3} concentrations. However, the ability to accommodate variation in the sludge composition limits the ability to utilize alternative frits for potential improvements in melt rate. Frit 535, which may offer improvements in melt rate due to its increased B2O3 concentration, produced acceptable glasses with the baseline SB6 composition at waste loadings of 34 and 42%. However, the PCCS MAR results showed that it is not as robust as Frit 418 in accommodating variation in the sludge composition. Preliminary melt rate testing was completed in the Melt Rate Furnace (MRF) with four candidate frits for SB6. These four frits were selected to evaluate the impacts of B{sub 2}O{sub 3} and Na{sub 2}O concentrations in the frit relative to those of Frit 418, although they are not necessarily candidates for SB6 vitrification. Higher concentrations of B{sub 2}O{sub 3} in the frit relative to that of Frit 418 appeared to improve melt rate. However, when a higher concentration of B{sub 2}O{sub 3} was coupled

  16. On the thermal and magnetic histories of Earth and Venus: Influences of melting, radioactivity, and conductivity

    Science.gov (United States)

    Driscoll, P.; Bercovici, D.

    2014-11-01

    The study of the thermal evolution of Earth's interior is uncertain and controversial in many respects, from the interpretation of petrologic observations used to infer the temperature and dynamics of the interior, to the physics and material properties governing heat transport. The thermal history of Venus is even more uncertain, but the lack of a dynamo at present in an otherwise similar planet may provide additional constraints on terrestrial planet evolution. In this paper a one dimensional thermal history model is derived that includes heat loss due to mantle melt eruption at the surface to explore its influence on the thermal and magnetic history of Earth and Venus. We show that the thermal catastrophe of Earth's mantle, which occurs for a present day Urey ratio of 1/3 and convective heat loss exponent of β=1/3, can be avoided by assuming a rather high core heat flow of ∼15 TW. This core heat flow also avoids the new core paradox by allowing for the geodynamo to be thermally powered prior to inner core growth for core thermal conductivities as high as 130 Wm K. Dynamo regime diagrams demonstrate that the mantle melt eruption rate has a minor effect on the history of mobile lid planets due to the efficiency of plate tectonic convective heat loss. However, if Earth were in a stagnant lid regime prior to 2.5 Ga, as has been proposed, then at least ∼5% of mantle melt is required to erupt in order to thermally power the paleodynamo at that time. Dynamo regime diagrams for stagnant lid Venus models indicate that more than half of the melt generated in the mantle is required to erupt in order to overcome the insulation imposed by the stagnant lid and drive a dynamo. This implies that with an Earth-like mantle radioactivity the Venusian dynamo shut down ∼0.3 Ga for an eruption efficiency of 50%, and ∼3 Ga for an eruption efficiency of zero. Consequently, a stagnant lid alone does not prevent a core dynamo if melting of the upper mantle provides a substantial

  17. Melt Absorbability of Iron Ore Nuclei and Its Influence on Suitable Liquid Content of Sintered Body

    Science.gov (United States)

    Wu, Sheng-Li; Su, Bo; Qi, Yuan-Hong; Kou, Ming-Yin; Li, Yuan; Zhang, Wei-Li

    2017-10-01

    Sinter quasi-particles consist of nuclei particles and adhering fines. Therefore, reaction properties of the nuclei ore will ultimately affect the bonding strength of the sintered body. In this study, micro-sintering tests were conducted to explore the melt absorbability of nuclei ore and its effect on the suitable liquid content of the sintered body. The results showed that the melt absorbability is negatively correlated with the lowest assimilation temperature, and the most important mineralogy factor influencing melt absorbability is iron mineral type. The reaction behaviors of melts containing SiO2 or Al2O3 substrates are different, and the reaction process of the melt containing SiO2 is more complicated. In addition, the bonding strength of the sintered body is collectively determined by the liquid phase fluidity of adhering fines and the assimilability of nuclei ore. The high melt absorbability has an adverse effect on bonding strength, and it requires adhering fines to provide more primary melts to meet the requirements for sintered body bonding strength. In the condition with the same liquid content, for nuclei ore with stronger melt absorbability, an appropriate increase in the adhering fines ratio and reduction in segregation basicity are more conducive to improving the bonding strength.

  18. Humid storage conditions increase the dissolution rate of diazepam from solid dispersions prepared by melt agglomeration

    DEFF Research Database (Denmark)

    Jørgensen, Anna Cecilia; Torstenson, Anette Seo

    2008-01-01

    The purpose of this study is to investigate the effect of cooling mode and storage conditions on the dissolution rate of a solid dispersion prepared by melt agglomeration. The aim has been to relate this effect to the solid state properties of the agglomerates. The cooling mode had an effect on t...

  19. IMPACT OF SMALL COLUMN ION EXCHANGE STREAMS ON DWPF GLASS FORMULATION MELT RATE STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Miller, D.; Koopman, D.

    2011-04-26

    This study was undertaken to evaluate the potential impacts of the Small Column Ion Exchange (SCIX) streams - particularly the addition of Monosodium Titanate (MST) and Crystalline Silicotitanate (CST) - on the melt rate of simulated feed for the Defense Waste Processing Facility (DWPF). Additional MST was added to account for contributions from the Salt Waste Processing Facility (SWPF). The Savannah River National Laboratory (SRNL) Melt Rate Furnace (MRF) was used to evaluate four melter feed compositions: two with simulated SCIX and SWPF material and two without. The Slurry-fed Melt Rate Furnace (SMRF) was then used to compare two different feeds: one with and one without bounding concentrations of simulated SCIX and SWPF material. Analyses of the melter feed materials confirmed that they met their targeted compositions. Four feeds were tested in triplicate in the MRF. The linear melt rates were determined by using X-ray computed tomography to measure the height of the glass formed along the bottom of the beakers. The addition of the SCIX and SWPF material reduced the average measured melt rate by about 10% in MRF testing, although there was significant scatter in the data. Two feeds were tested in the SMRF. It was noted that the ground CST alone (ground CST with liquid in a bucket) was extremely difficult to resuspend during preparation of the feed with material from SCIX and SWPF. This feed was also more difficult to pump than the material without MST and CST due to settling occurring in the melter feed line, although the yield stress of both feeds was high relative to the DWPF design basis. Steady state feeding conditions were maintained for about five hours for each feed. There was a reduction in the feed and pour rates of approximately 15% when CST and MST were added to the feed, although there was significant scatter in the data. Analysis of samples collected from the SMRF pour stream showed that the composition of the glass changed as expected when MST and

  20. Melting rates beneath Hawaii: Evidence from uranium series isotopes in recent lavas

    Science.gov (United States)

    Cohen, Anthony S.; O'Nions, R. Keith

    1993-12-01

    U-238, Th-232, Th-230 and Ra-226 abundances have been measured in six samples of recent Hawaiian basalt by high precision mass spectrometry, in an attempt to compare the melting process in plumes and at spreading ridges. The data reveal a very small range in (Th-230/U-238) activity ratio up to a maximum value of 1.02 +/- 0.01, and (Ra-226/Th-230) activity ratios which lie between 1.10 +/- 0.015 and 1.19 +/- 0.02. U-Th and Ra-Th abundances are linearly correlated demonstrating that the disequilibria predate crystallization and differentiation. Using recently published estimates for the bulk partition coefficients of U and Th, the results are consistent with melting rates greater than 10(exp -3) kg/cu m/a at porosities less than 10(exp -3) for dynamic fractional melting in the garnet stability field.

  1. The influence of pre-melting in laser drilling with temporally modulated pulse

    Science.gov (United States)

    Duan, Wenqiang; Wang, Kedian; Dong, Xia; Mei, Xuesong; Wang, Wenjun; Fan, Zhengjie; Lv, Jing

    2016-05-01

    Laser drilling by temporally modulated pulse is a promising technique and has many advantages compared with normal pulse drilling. In this work, the effect of modulated pulse comprising pre-heating front and sharp trail was mainly studied. The function of the former was to pre-melt the radiated material, and the latter was to expel the liquid melt from the molten pool, thus to form a blind hole. While the trail subpulse was kept constant, the difference in the pre-heating subpulse parameter could cause a considerable influence on the hole quality and drilling efficiency. The depth and volume of the molten pool were proportional to the pre-heating energy, and inversely proportional to the pre-heating duration. With pre-heating subpulses of proper parameters, the sharp trail subpulse was very effective in expelling the melt liquid, leaving only a small quantity of melt to re-solidify as the recast layer, which was observably thinner compared with the holes drilled using the normal pulse mode. In the pre-melting process, the directional melt flow and heat conduction were found to be the reasons why the deep melting phenomenon had occurred.

  2. Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica

    OpenAIRE

    Makinson, Keith; Holland, Paul R.; Jenkins, Adrian; Nicholls, Keith W.; Holland, David M.

    2011-01-01

    An isopycnic coordinate ocean circulation model is applied to the ocean cavity beneath Filchner-Ronne Ice Shelf, investigating the role of tides on sub-ice shelf circulation and ice shelf basal mass balance. Including tidal forcing causes a significant intensification in the sub-ice shelf circulation, with an increase in melting (3-fold) and refreezing (6-fold); the net melt rate and seawater flux through the cavity approximately doubles. With tidal forcing, the spatial pattern and magnitude ...

  3. Modern methods for the quality management of high-rate melt solidification

    Science.gov (United States)

    Vasiliev, V. A.; Odinokov, S. A.; Serov, M. M.

    2016-12-01

    The quality management of high-rate melt solidification needs combined solution obtained by methods and approaches adapted to a certain situation. Technological audit is recommended to estimate the possibilities of the process. Statistical methods are proposed with the choice of key parameters. Numerical methods, which can be used to perform simulation under multifactor technological conditions, and an increase in the quality of decisions are of particular importance.

  4. Influence of melt-treatment on material constants of aluminum sheet used for easy-open can during hot deformation

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-lu; FU Gao-sheng; CHEN Wen-zhe

    2006-01-01

    The isothermal compression test at elevated temperature was carried out for aluminum sheets prepared by different melt-treatment methods with aid of dynamic hot/mechanical simulation experimental technology. The material constants of hot deformation have been solved by multivariate regression directly. Influence of metallurgy factors on the constants was analyzed. The results show that at some strain, the relationship of sheets' flow stress with deformation temperature and strain rate can be expressed more suitably with Arrhenius equation modified by hyperbolic sine function. Structure factor A1,stress-level coefficient α, strain rate sensibility exponent m and deformation activation energy Q all increase with increment of strain, while stress exponent n decreases gradually. The bigger α value or the smaller n value is, the more obvious the dynamic softening is, but the α value will increase for the metallurgy defects existing in the sheets. Influence of melt-treatment on Q depends upon the synthesis effect of all kinds of metallurgy defects. The Q and n values of the sheet prepared by high-efficient melt-treatment are the least, while the m value is the biggest, and the sheet can deform easily and evenly.

  5. Evaluation of quartz melt rate furnace with the nitric-glycolic flowsheet

    Energy Technology Data Exchange (ETDEWEB)

    Williams, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Miller, D. H. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-03

    The Savannah River National Laboratory (SRNL) was tasked to support validation of the Defense Waste Processing Facility (DWPF) melter offgas flammability model for the Nitric-Glycolic (NG) flowsheet. The work is supplemental to the Cold Cap Evaluation Furnace (CEF) testing conducted in 20141 and the Slurry-fed Melt Rate Furnace (SMRF) testing conducted in 20162 that supported Deliverable 4 of the DWPF & Saltstone Facility Engineering Technical Task Request (TTR).3 The Quartz Melt Rate Furnace (QMRF) was evaluated as a bench-scale scoping tool to potentially be used in lieu of or simply prior to the use of the larger-scale SMRF or CEF. The QMRF platform has been used previously to evaluate melt rate behavior and offgas compositions of DWPF glasses prepared from the Nitric-Formic (NF) flowsheet but not for the NG flowsheet and not with continuous feeding.4 The overall objective of the 2016-2017 testing was to evaluate the efficacy of the QMRF as a lab-scale platform for steady state, continuously fed melter testing with the NG flowsheet as an alternative to more expensive and complex testing with the SMRF or CEF platforms.

  6. Lattice model of linear telechelic polymer melts. II. Influence of chain stiffness on basic thermodynamic properties

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wen-Sheng, E-mail: wsxu@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Freed, Karl F., E-mail: freed@uchicago.edu [James Franck Institute, The University of Chicago, Chicago, Illinois 60637 (United States); Department of Chemistry, The University of Chicago, Chicago, Illinois 60637 (United States)

    2015-07-14

    The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ϕ or temperature T is high, but opposes self-assembly when both ϕ and T are sufficiently low. This allows us to identify a boundary line in the ϕ-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.

  7. Influence of Additive Silica on the Laser Melting of the Ceramic Coatings

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The influence of additive silica on the microstructure of plasma sprayed Al2O3 and Al2O3+13 wt pct TiO2 ceramiccoatings at laser melting has been investigated in this study. At the laser melting, additive silica in Al2O3 ceramiccoating can reduce the stress of cooling shrinkage generated during solidification. Moreover, silica can render finersize of grains of the melting layer and form continuous glassy matter around the grain boundaries so as to reducefurther the cooling stresses and to suppress the formation and spreading of cracks. On the other hand, at the lasermelting, TiO2 reacts with Al2O3 and transforms into TiAl2Os. The latter new phase has great and anisotropiccoefficients of thermal expansion leading to big and asymmetrical stresses and thus to form cracks in the meltinglayer of Al2O3+13 wt pct TiO2 coating. Due to the fact that the influence of additive silica on the suppression of theformation of cracks is rather limited and cannot counterbalance the negative effect of TiAl2O5, thus the melting layerof Al2O3+13 wt pct TiO2 coating doped with 3 wt pct SiO2 cracks also. Nevertheless, TiO2 can greatly developthe wear resistance of the ceramic coating as sprayed or laser melted.

  8. Lattice model of linear telechelic polymer melts. II. Influence of chain stiffness on basic thermodynamic properties

    Science.gov (United States)

    Xu, Wen-Sheng; Freed, Karl F.

    2015-07-01

    The lattice cluster theory (LCT) for semiflexible linear telechelic melts, developed in Paper I, is applied to examine the influence of chain stiffness on the average degree of self-assembly and the basic thermodynamic properties of linear telechelic polymer melts. Our calculations imply that chain stiffness promotes self-assembly of linear telechelic polymer melts that assemble on cooling when either polymer volume fraction ϕ or temperature T is high, but opposes self-assembly when both ϕ and T are sufficiently low. This allows us to identify a boundary line in the ϕ-T plane that separates two regions of qualitatively different influence of chain stiffness on self-assembly. The enthalpy and entropy of self-assembly are usually treated as adjustable parameters in classical Flory-Huggins type theories for the equilibrium self-assembly of polymers, but they are demonstrated here to strongly depend on chain stiffness. Moreover, illustrative calculations for the dependence of the entropy density of linear telechelic polymer melts on chain stiffness demonstrate the importance of including semiflexibility within the LCT when exploring the nature of glass formation in models of linear telechelic polymer melts.

  9. Influence of Flame Retardants on the Melt Dripping Behaviour of Thermoplastic Polymers

    Directory of Open Access Journals (Sweden)

    Melissa Matzen

    2015-08-01

    Full Text Available Melt flow and dripping of the pyrolysing polymer melt can be both a benefit and a detriment during a fire. In several small-scale fire tests addressing the ignition of a defined specimen with a small ignition source, well-adjusted melt flow and dripping are usually beneficial to pass the test. The presence of flame retardants often changes the melt viscosity crucially. The influence of certain flame retardants on the dripping behaviour of four commercial polymers, poly(butylene terephthalate (PBT, polypropylene (PP, polypropylene modified with ethylene-propylene rubber (PP-EP and polyamide 6 (PA 6, is analysed based on an experimental monitoring of the mass loss due to melt dripping, drop size and drop temperature as a function of the furnace temperature applied to a rod-shaped specimen. Investigating the thermal transition (DSC, thermal and thermo-oxidative decomposition, as well as the viscosity of the polymer and collected drops completes the investigation. Different mechanisms of the flame retardants are associated with their influence on the dripping behaviour in the UL 94 test. Reduction in decomposition temperature and changed viscosity play a major role. A flow limit in flame-retarded PBT, enhanced decomposition of flame-retarded PP and PP-EP and the promotion of dripping in PA 6 are the salient features discussed.

  10. Observations of melt rate as a function of arc power, CO pressure, and electrode gap during vacuum consumable arc remelting of Inconel 718

    Science.gov (United States)

    Zanner, F. J.; Bertram, L. A.; Adasczik, C.; O'Brien, T.

    1984-01-01

    Statistically designed experiments were conducted at two different production melt shops to evaluate the influence of arc power, CO pressure, and electrode gap on melt rate. Approximately 11,000 kg of Inconel 718 alloy 0.4 m diameter electrodes were vacuum consumable arc remelted into 0.5 m diameter ingots. Analysis of the experimental results revealed that melting efficiency (melting rate/kW) was maximized when CO pressure and electrode gap were held at low levels. Under these conditions, the heat distribution (created by the vacuum arc) on the electrode tip and the molten pool exhibited macro uniformity. Increased CO pressure and/or electrode gap depressed the melt rate, and at 13.3 Pa (100 microns) and a 0.050 m electrode gap, this depression exceeds 46 pct. Increasing these parameters also changed the arc behavior to that of a constricted arc with a highly localized heat input. It is hypothesized that the change from the usual diffuse arc to this constricted arc results in intense Lorentz pumping in a localized region of the molten pool atop the ingot causing fluid flow transients. These transients could, in turn, create solidification defects.

  11. Experimental investigation of low-frequency pulsed Lorentz force influence on the motion of Galinstan melt

    Directory of Open Access Journals (Sweden)

    Diana A. Musaeva

    2016-10-01

    Full Text Available The paper presents the results of the numerical and physical experiments, aimed at assessing the influence of pulsed force of electromagnetic field on the melt motion and the fluid velocities. The experiment was performed on the eutectic alloy Galinstan in the cylindrical volume, where an ultrasonic Doppler velocimeter was employed for velocity measurements under conditions of pulsed and steady EM field application. A numerical simulation of the melt flow, forced by the steady EM force, involved a 2D axisymmetric model. The k-ε turbulence model was used to obtain the information about the melt velocities. The verification of the numerical model was carried out for the steady case. The effects of pulsed and steadily applied Lorentz force were compared using the physical experiment. An intensity of the velocity pulsations in Galinstan for the pulsed frequencies in the range from 0.05 to 1Hz considerably exceeded the values measured in the permanently stirred melt. For higher values of pulsed frequencies (from 1 to 10Hz the effect decreases and only slightly differs from the influence of the permanently applied Lorentz force.

  12. Quantifying melt production and degassing rate at mid-ocean ridges from global mantle convection models with plate motion history

    Science.gov (United States)

    Li, Mingming; Black, Benjamin; Zhong, Shijie; Manga, Michael; Rudolph, Maxwell L.; Olson, Peter

    2016-07-01

    The Earth's surface volcanism exerts first-order controls on the composition of the atmosphere and the climate. On Earth, the majority of surface volcanism occurs at mid-ocean ridges. In this study, based on the dependence of melt fraction on temperature, pressure, and composition, we compute melt production and degassing rate at mid-ocean ridges from three-dimensional global mantle convection models with plate motion history as the surface velocity boundary condition. By incorporating melting in global mantle convection models, we connect deep mantle convection to surface volcanism, with deep and shallow mantle processes internally consistent. We compare two methods to compute melt production: a tracer method and an Eulerian method. Our results show that melt production at mid-ocean ridges is mainly controlled by surface plate motion history, and that changes in plate tectonic motion, including plate reorganizations, may lead to significant deviation of melt production from the expected scaling with seafloor production rate. We also find a good correlation between melt production and degassing rate beneath mid-ocean ridges. The calculated global melt production and CO2 degassing rate at mid-ocean ridges varies by as much as a factor of 3 over the past 200 Myr. We show that mid-ocean ridge melt production and degassing rate would be much larger in the Cretaceous, and reached maximum values at ˜150-120 Ma. Our results raise the possibility that warmer climate in the Cretaceous could be due in part to high magmatic productivity and correspondingly high outgassing rates at mid-ocean ridges during that time.

  13. Self-heating probe instrument and method for measuring high temperature melting volume change rate of material

    Science.gov (United States)

    Wang, Junwei; Wang, Zhiping; Lu, Yang; Cheng, Bo

    2013-03-01

    The castings defects are affected by the melting volume change rate of material. The change rate has an important effect on running safety of the high temperature thermal storage chamber, too. But the characteristics of existing measuring installations are complex structure, troublesome operation and low precision. In order to measure the melting volume change rate of material accurately and conveniently, a self-designed measuring instrument, self-heating probe instrument, and measuring method are described. Temperature in heating cavity is controlled by PID temperature controller; melting volume change rate υ and molten density are calculated based on the melt volume which is measured by the instrument. Positive and negative υ represent expansion and shrinkage of the sample volume after melting, respectively. Taking eutectic LiF+CaF2 for example, its melting volume change rate and melting density at 1 123 K are -20.6% and 2 651 kg·m-3 measured by this instrument, which is only 0.71% smaller than literature value. Density and melting volume change rate of industry pure aluminum at 973 K and analysis pure NaCl at 1 123 K are detected by the instrument too. The measure results are agreed with report values. Measuring error sources are analyzed and several improving measures are proposed. In theory, the measuring errors of the change rate and molten density which are measured by the self-designed instrument is nearly 1/20-1/50 of that measured by the refitted mandril thermal expansion instrument. The self-designed instrument and method have the advantages of simple structure, being easy to operate, extensive applicability for material, relatively high accuracy, and most importantly, temperature and sample vapor pressure have little effect on the measurement accuracy. The presented instrument and method solve the problems of complicated structure and procedures, and large measuring errors for the samples with high vapor pressure by existing installations.

  14. The role of partial melting and extensional strain rates in the development of metamorphic core complexes

    Science.gov (United States)

    Rey, P. F.; Teyssier, C.; Whitney, D. L.

    2009-11-01

    Orogenic collapse involves extension and thinning of thick and hot (partially molten) crust, leading to the formation of metamorphic core complexes (MCC) that are commonly cored by migmatite domes. Two-dimensional thermo-mechanical Ellipsis models evaluate the parameters that likely control the formation and evolution of MCC: the nature and geometry of the heterogeneity that localizes MCC, the presence/absence of a partially molten layer in the lower crust, and the rate of extension. When the localizing heterogeneity is a normal fault in the upper crust, the migmatite core remains in the footwall of the fault, resulting in an asymmetric MCC; if the localizing heterogeneity is point like region within the upper crust, the MCC remains symmetric throughout its development. Therefore, asymmetrically located migmatite domes likely reflect the dip of the original normal fault system that generated the MCC. Modeling of a severe viscosity drop owing to the presence of a partially molten layer, compared to a crust with no melt, demonstrates that the presence of melt slightly enhances upward advection of material and heat. Our experiments show that, when associated with boundary-driven extension, far-field horizontal extension provides space for the domes. Therefore, the buoyancy of migmatite cores contributes little to the outer envelope of metamorphic core complexes, although it may play a significant role in the internal dynamics of the partially molten layer. The presence of melt also favors heterogeneous bulk pure shear of the dome as opposed to the bulk simple shear, which dominates in melt-absent experiments. Melt presence affects the shape of P-T-t paths only slightly for material located near the top of the low-viscosity layer but leads to more complex flow paths for material inside the layer. The effect of extension rate is significant: at high extension rate (cm yr - 1 in the core complex region), partially molten crust crystallizes and cools along a high

  15. Influence of melt structure on the crystallization behavior and polymorphic composition of polypropylene random copolymer

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bin [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Ecole Normale Supérieure, CNRS-ENS-UPMC UMR 8640, 24 Rue Lhomond, Paris 75005 (France); Chen, Zhengfang [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Kang, Jian, E-mail: jiankang@scu.edu.cn [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China); Yang, Feng; Chen, Jinyao; Cao, Ya; Xiang, Ming [State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu 610065 (China)

    2015-03-20

    Highlights: • We prepared β-PPR and studied its crystallization behavior with different melt structures. • We observed surprising synergetic effect between β-NA and the ordered structures. • We explored the nature of ordered structures by calculating the equilibrium temperature. - Abstract: Polypropylene random copolymer (PPR) is one of important polypropylene types for the application fields. However, due to the random copolymer chain configuration, it is difficult to obtain high proportion of β-phase even under the influence of β-nucleating agent (β-NA). In this study, the melt structure (namely, the content of ordered structures in the melt) of β-nucleated ethylene-copolymerized PPR (β-PPR) was controlled by tuning the fusion temperature (T{sub f}), and its impact on the crystallization and polymorphic behavior of β-PPR was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), polarized optical microscopy (PLM) and scanning electronic microscopy (SEM). The result revealed that compared with the β-nucleated iPP homo-polymer, it is more difficult for β-PPR to form β-crystals; interestingly, when T{sub f} is in the temperature range of 162–173 °C, the ordered structures survived in melt exhibit high β-nucleation efficiency under the influence of β-NA, resulting in significant increase of β-phase proportion and evident variation of crystalline morphology, which is called the Ordered Structure Effect (OSE). Moreover, through investigating the self-nucleation behavior and equilibrium melting temperature of pure PPR (non-nucleated PPR), the physical nature of the lower and upper limiting T{sub f} temperatures for the occurrence of OSE in β-PPR was explored; the role of ethylene co-monomer in the occurrence of OSE was discussed.

  16. Mathematical Modeling of the Melting Rate of Metallic Particles in the Electric Arc Furnace

    National Research Council Canada - National Science Library

    González, O. J. P; Ramírez-Argáez, Marco A; Conejo, A. N

    2010-01-01

    A computational fluid dynamics model coupled to a lagrangian model of melting/solidifying particles has been developed to describe the melting kinetics of metallic particles in an industrial Electric Arc Furnace (EAF...

  17. Melt Rate Improvement for DWPF MB3: Foaming Theory and Mitigation Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Peeler, D.K.

    2001-07-24

    The objective of this research is to enhance the basic understanding of the role of glass chemistry, including the chemical kinetics of pre-melting, solid state reactions, batch melting, and the reaction pathways in glass and/or acid addition strategy changes on the overall melting process for the Defense Waste Processing Facility (DWPF) Macrobatch 3 (MB3).

  18. Influence of isothermal approximation on the phase-field simulation of directional growth in undercooled melt

    Institute of Scientific and Technical Information of China (English)

    于艳梅; 杨根仓; 赵达文; 吕衣礼

    2003-01-01

    By using the phase-field approach, we have simulated the directional growth of alloys in undercooled molten states under the isothermal and nonisothermal conditions. The influences of the isothermal approximation on simulation results are discussed. We found that for undercooling greater than 25K, the isothermal approximation overestimates the interface growth velocity and reduces a critical velocity for an absolute stable planar interface, thus in this simulation,the interface morphology shows the plane-cell-plane transition with increasing initial undercooling of the melt, and the planar interface obtained under a large undercooling is absolutely stable. Whereas in the nonisothermal simulation,only plane-cell transition occurs in the same range of the initial undercoolings of the melt, and the planar interface tends to be destabilized and evolve into cells.

  19. Influence of rare earth oxides on the non-isothermal crystallization of phosphosilicate melts during cooling

    DEFF Research Database (Denmark)

    Liu, S.J.; Shan, Z.T.; Fu, G.Z.;

    2014-01-01

    We report a detailed calorimetric study concerning the influence of Yb2O3 and Er2O3 on the non-isothermal crystallization in phosphosilicate melts. The results show that Yb3+/Er3+ ions promote the Zn2SiO4 crystal formation, but suppress the Na3PO4 and AlPO4 formation during cooling. The non......-isothermal melt-crystallization kinetics can be well described by the Avrami model. The activation energy Ee of crystallization in both the undoped and Yb3+/Er3+ codoped samples during cooling is determined using the differential iso-conversional method of Friedman. The Ee value decreases with crystallinity (θ...

  20. The influence of build parameters on the microstructure during electron beam melting of Titanium6Aluminum4Vanadium

    Science.gov (United States)

    Puebla, Karina

    properties decreased as the porosity increased for tensile testing and Rockwell C-scale (HR C), while Vickers hardness (HV) measurements increased and are related to the microstructure. The different build orientations of the specimens produced different mechanical properties since the orientation of the fabricated specimens impact the local heat transfer flow. This influenced the microstructure where the specimens oriented horizontally cooled more rapidly than those built vertically. Statistically significant differences in mechanical properties were found as an effect of melt scan rate. The statistical analyses that were done can help identify and classify fabrication parameters on mechanical properties for EBM-fabricated products. Optical images demonstrated the presence of alpha and beta phases, and alpha'-martensite with slight differences in microstructure. Dislocation substructures were observed in acicular alpha-plates from TEM images and alpha, beta, and alpha'-phase features. Mechanical and thermal treatment on Ti6Al4V can generate different microstructures promoting Ti6Al4V as an evolutionary alloy. Tailored mechanical properties of complex 3-dimensional end-use products can be achieved by modifying the building parameters of the EBM system. The EBM system can facilitate the process of manufacturing components by varying build parameters in order to obtain desirable physical and mechanical properties. Once the desired properties for Ti6Al4V are established, the fabrication process will lead to more successful end-use products.

  1. [Factors that influence student ratings of instruction].

    Science.gov (United States)

    Chae, Su Jin; Choung, Yun Hoon; Chung, Yoon Sok

    2015-03-01

    The purpose of this study was to examine the validity of student ratings of instruction by analyzing their relationships with several variables, including gender, academic rank, specialty, teaching time, and teaching method, at a medical school. This study analyzed the student ratings of 297 courses at Ajou University School of Medicine in 2013. SPSS version 12.0 was used to analyze the data and statistics by t-test, analysis of variance, and Scheffe test. There were no statistically significant differences in student ratings between gender, rank, and specialty. However, student ratings were significantly influenced by teaching times and methods (pStudent ratings were high for teaching times of 10 hours or more and small-group learning, compared with lectures. There was relatively mean differences in students ratings by teaching times, specialty and rank, although the difference in ratings was not statistically significant. Student ratings can be classified by teaching time and method for summative purposes. To apply student ratings to the evaluation of the performance of faculty, further studies are needed to analyze the variables that influence student ratings.

  2. Experimental investigations of influence of pressure on the solubility of sulfur in silicate melts.

    Science.gov (United States)

    Kostyuk, Anastasia; Gorbachev, Nikolay

    2010-05-01

    Sulfide-silicate demixing of silicate melts on immiscible silicate and sulfide liquids occurs at magma sulfur saturation. This type of liquation plays an important role in geochemistry of mantle magmas, in processes of magmatic differentiation, and in ore deposit formation. The major parameter defining sulfide-silicate stratification of silicate melts is solubility of sulfur in magmas. It is considered that «solubility of sulfur» is concentration of sulfur in silicate melts. The previous researches have established positive dependence of solubility of sulphur on temperature [1, 2], melt composition [3, 4], oxidation-reduction conditions [5, 6] and our experimental data confirm it. However, available data does not give a simple answer about dependence of solubility of sulfur from pressure in modelling and natural "dry" sulfide-saturated silicate melts. The reason of difference in experiments remains not clear and further work is needed on this topic. In this paper, we report our findings on the influence of pressure on the solubility of sulfur in hydrous magnesian melts. This melts are represent by olivine basalt - picrite, coexisting with Fe-Cu-Ni sulfide melt and harzburgite (Ol+Opx) and it was investigated in a temperature range from 1200 to 1350°С and a pressure range from 0.2 to 2.5 GPa. Experiments were carried out on the piston-cylinder at Р=1-2.5GPa and in an internal-heated pressure vessels at P=0.2-0.6 GPa by a quenching technique. Our findings disagree with all previous studies demonstrating the positive [7] or negative [8, 9] influence of pressure on the solubility of sulfur in silicate melts. Our researches have shown complicated influence of pressure. Concentration of sulfur in glasses increases with increase in pressure from 0.2 to 0.6 GPa in experiments where andesite was used as a starting material. The sulfur concentration increases from 0.09 wt.% at 0.2 GPa to 0.4 wt.% at 0.6 GPa and Т=1200°С. In hydrous magnesian basalts (12-18 % MgO), we

  3. Estimating Influence of Crystallizing Latent Heat on Cooling-Crystallizing Process of a Granitic Melt and Its Geological Implications

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bangtong; WU Junqi; LING Hongfei; CHEN Peirong

    2008-01-01

    Based on the theory of thermal conductivity, in this paper we derived a formula to estimate the prolongation period (AtL) of cooling-crystallization process of a granitic melt caused by latent heat of crystallization as follows: △t=QL×△tcol/TM-TC×CP where TM is initial temperature of the granite melt, Tc crystallization temperature of the granite melt,CP specific heat, △tcol cooling period of a granite melt from its initial temperature (TM) to its crystallization temperature (TC), QL latent heat of the granite melt. The cooling period of the melt for the Fanshan granodiorite from its initial temperature (900℃) to crystallization temperature (600℃) could be estimated ~210,000 years if latent heat was not considered. Calculation for the Fanshan melt using the above formula yields a AtL value of~190,000 years, which implies that the actual cooling period within the temperature range of 900℃-600℃ should be 400,000 years. This demonstrates that the latent heat produced from crystallization of the granitic melt is a key factor influencing the cooling-crystallization process of a granitic melt, prolongating the period of crystallization and resulting in the large emplacement-crystallization time difference (ECTD) in granite batholith.

  4. Modeling of ocean-induced ice melt rates of five west Greenland glaciers over the past two decades

    Science.gov (United States)

    Rignot, E.; Xu, Y.; Menemenlis, D.; Mouginot, J.; Scheuchl, B.; Li, X.; Morlighem, M.; Seroussi, H.; den Broeke, M. van; Fenty, I.; Cai, C.; An, L.; Fleurian, B. de

    2016-06-01

    High-resolution, three-dimensional simulations from the Massachusetts Institute of Technology general circulation model ocean model are used to calculate the subaqueous melt rate of the calving faces of Umiamako, Rinks, Kangerdlugssup, Store, and Kangilerngata glaciers, west Greenland, from 1992 to 2015. Model forcing is from monthly reconstructions of ocean state and ice sheet runoff. Results are analyzed in combination with observations of bathymetry, bed elevation, ice front retreat, and glacier speed. We calculate that subaqueous melt rates are 2-3 times larger in summer compared to winter and doubled in magnitude since the 1990s due to enhanced subglacial runoff and 1.6 ± 0.3°C warmer ocean temperature. Umiamako and Kangilerngata retreated rapidly in the 2000s when subaqueous melt rates exceeded the calving rates and ice front retreated to deeper bed elevation. In contrast, Store, Kangerdlugssup, and Rinks have remained stable because their subaqueous melt rates are 3-4 times lower than their calving rates, i.e., the glaciers are dominated by calving processes.

  5. Dissolution Rate of Steel Sheathing Through Plunging and Melt-Through Methods

    Science.gov (United States)

    Rivera-Martínez, Elis A.; Beers, Mark; Scheller, Eric; Yu, Edward

    2017-10-01

    In an effort to determine the dissolution rate of the steel sheathing used in the production of cored wire, several experiments were conducted in the ASK Chemicals Metals Application Lab (MAL), in Dublin, Ohio. It is essential to understand that, when exposed to molten metal at a certain temperature/time, the low-carbon steel will dissolve, thereby exposing the contained alloy to the molten metal. This article presents two separate experiments that will provide a better understanding of the dissolution rates of the steel sheathing used in the 9-mm cored wire. The first experiment was an immersion test, where the finished product (cored wire containing a ferroalloy) was submerged in molten metal for a predetermined amount of time. The length of the cored wire was measured before and after the immersion to gauge the effect of time and temperature on the dissolution characteristics. The second experiment was conducted to examine the time and temperature needed to melt through a flat piece of metal sheathing. For this experiment, a flat piece of metal sheathing was placed over the down sprue of a sand-based pouring box. The basin was filled with molten metal at a predetermined temperature, and a high-speed camera and high-temperature thermocouples were used to record the temperature and the time needed to dissolve the metal sheathing.

  6. Dissolution Rate of Steel Sheathing Through Plunging and Melt-Through Methods

    Science.gov (United States)

    Rivera-Martínez, Elis A.; Beers, Mark; Scheller, Eric; Yu, Edward

    2017-08-01

    In an effort to determine the dissolution rate of the steel sheathing used in the production of cored wire, several experiments were conducted in the ASK Chemicals Metals Application Lab (MAL), in Dublin, Ohio. It is essential to understand that, when exposed to molten metal at a certain temperature/time, the low-carbon steel will dissolve, thereby exposing the contained alloy to the molten metal. This article presents two separate experiments that will provide a better understanding of the dissolution rates of the steel sheathing used in the 9-mm cored wire. The first experiment was an immersion test, where the finished product (cored wire containing a ferroalloy) was submerged in molten metal for a predetermined amount of time. The length of the cored wire was measured before and after the immersion to gauge the effect of time and temperature on the dissolution characteristics. The second experiment was conducted to examine the time and temperature needed to melt through a flat piece of metal sheathing. For this experiment, a flat piece of metal sheathing was placed over the down sprue of a sand-based pouring box. The basin was filled with molten metal at a predetermined temperature, and a high-speed camera and high-temperature thermocouples were used to record the temperature and the time needed to dissolve the metal sheathing.

  7. Ascent Rates from Melt Embayments: Insights into the Eruption Dynamics of Arc Volcanoes

    Science.gov (United States)

    Ruprecht, P.; Lloyd, A. S.; Hauri, E.; Rose, W. I.; Gonnermann, H. M.; Plank, T. A.

    2014-12-01

    A significant fraction of the magma that is added from the mantle to the subvolcanic plumbing system ultimately erupts at the surface. The initial volatile content of the magmas as well as the interplay between volatile loss and magma ascent plays a significant role in determining the eruption style (effusive versus explosive) as well as the magnitude of the eruption. The October 17, 1974 sub-Plinian eruption of Volcán de Fuego represents a particularly well-characterized system in terms of volatile content and magma chemistry to investigate the relation between initial water content of the magmas and the ascent rate. By modeling volatile element distribution in melt embayments through diffusion and degassing during ascent we can estimate magma ascent from the storage region in the crust to the surface. The novel aspect is the measurement of concentration gradients multiple volatile elements (in particular CO2, H2O, S) at fine-scale (5-10 μm) using the NanoSIMS. The wide range in diffusivity and solubility of these different volatiles provides multiple constraints on ascent timescales over a range of depths. H2O, CO2, and S all decrease toward the embayment outlet bubble documenting the loss of H2O and CO2 compared to an extensive melt inclusion suite from the same day of the eruption. The data is best described by a two-stage model. At high pressure (>145 MPa) decompression is slow (0.05- 0.3 MPa/s) and CO2 is bled off predominantly. At shallow levels decompression accelerates to 0.3-0.5 MPa/s at the point of H2O exsolution, which strongly affects the buoyancy of the ascending magma. The magma ascent rates presented are among the first for explosive basaltic eruptions and demonstrate the potential of the embayment method for quantifying magmatic timescales associated with eruptions of different vigor. [1] Lloyd et al. (2014) JVGR, http://dx.doi.org/10.1016/j.jvolgeores.2014.06.002

  8. Estimate of influence of U-Th-K radiogenic heat on cooling process of granitic melt and its geological implications

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The U-Th-40K concentrations of granite are on 1―2 orders of magnitude greater than those of basal- tic-ultrabasic rocks. Radiogenic heat of a granitic melt has significant influence on the cool- ing-crystallization period of the melt. In this paper we derived a formula to calculate prolongation period (tA) of cooling-crystallization of a granitic melt caused by radiogenic heat. Calculation using this for- mula and radioactive element concentrations (U=5.31×10-6; Th=23.1×10-6; K=4.55%) for the biotite adamellite of the Jinjiling batholith shows that the tA of the adamellite is 1.4 times of the cooling period of the granitic melt without considering radiogenic heat from the initial temperature (Tm=960℃) to crystallization temperature (Tc=600℃) of the melt. It has been demonstrated that the radiogenic heat produced in a granitic melt is a key factor influencing the cooling-crystallization process of the granitic melt, and is likely one of the reasons for inconsistence between emplacement ages and crystallization ages of many Meso-Cenozoic granitoids.

  9. Process Influences on Laser-beam Melting of the Magnesium Alloy AZ91

    Science.gov (United States)

    Schmid, Dominik; Renza, Johanna; Zaeh, Michael F.; Glasschroeder, Johannes

    Magnesium's great lightweight potential and high biocompatibility render laser-beam melting of this metal increasingly interesting. Despite recent research activities in this field, the properties thereby achieved are still inadequate for industrial or medical use. Low surface quality caused by powder sintered to parts' boundaries is one of the main problems. This effect is discussed theoretically and examined on single tracks of the magnesium alloy AZ91. Welding-penetration depth and width was measured on a magnesium plate with and without a powder layer. For the derivation of suitable process parameters, structures with incrementally increasing hatch distances were built and microscopically analyzed. The influence on defect percentage and hardness of the parts was determined based on specimens manufactured with different layer thicknesses. The influence of the oxygen content on solids was analyzed by varying the process atmosphere.

  10. Influence of melt feeding scheme and casting parameters during direct-chill casting on microstructure of an AA7050 billet

    OpenAIRE

    Zhang, L; T. Subroto; Katgerman, L.; Eskin, DG; Miroux, A

    2012-01-01

    © The Minerals, Metals & Materials Society and ASM International 2012 Direct-chill (DC) casting billets of an AA7050 alloy produced with different melt feeding schemes and casting speeds were examined in order to reveal the effect of these factors on the evolution of microstructure. Experimental results show that grain size is strongly influenced by the casting speed. In addition, the distribution of grain sizes across the billet diameter is mostly determined by melt feeding scheme. Grains...

  11. Structural relaxation time and cooling rate of a melt in the glass transition region

    Science.gov (United States)

    Sanditov, D. S.; Sydykov, B. S.

    2015-03-01

    The nature of the parameter involved in the Bartenev equation qτg = C relating the cooling rate of a glass-forming melt to its structural relaxation time in the glass transition region is discussed on the basis of the Volkenshtein-Ptitsyn theory using a number of known relationships. It is established that parameter C for amorphous substances with the same fragility is linearly temperature dependent. This parameter is shown to equal the narrow temperature range δ T g characterizing the liquid-glass transition region (by Nemilov); i.e., C = δ T g. It is concluded that δ T g for most glassy systems is only ˜0.7% of the glass transition temperature T g. The narrowness of temperature range δ T g is explained by the small fluctuation volume fraction f g "frozen" at the glass transition temperature. The concept of a close relationship between constant C and the structural order at T g (i.e., the characteristic of the inner state of a nonequilibrium "frozen" amorphous system) is developed.

  12. Modeling of ocean-induced ice melt rates of five west Greenland glaciers over the past two decades

    NARCIS (Netherlands)

    Rignot, E.; Xu, Y.; Menemenlis, D.; Mouginot, J.; Scheuchl, B.; Li, X.; Morlighem, M.; Seroussi, H.; van den Broeke, M.|info:eu-repo/dai/nl/073765643; Fenty, I.; Cai, C.; An, L.; de Fleurian, B.

    2016-01-01

    High-resolution, three-dimensional simulations from the Massachusetts Institute of Technology general circulation model ocean model are used to calculate the subaqueous melt rate of the calving faces of Umiamako, Rinks, Kangerdlugssup, Store, and Kangilerngata glaciers, west Greenland, from 1992 to

  13. Influences of Preparation Conditions and Melt Treatment Procedures on Melt Treatment Performance of Al-5Ti-B and Al-10Sr Master Alloys

    Institute of Scientific and Technical Information of China (English)

    Pengfa FENG; Jinglin TANG; Xinyan JIN; Shuangshou LI; Daben ZENG

    2006-01-01

    The influences of preparation conditions of Al-5Ti-B (as-cast and hot-rolled) and Al-10Sr (as-cast and hotextruded) and melt treatment procedures on the grain refinement and modification performance of A356 alloy are experimentally studied. For the two master alloys, the 50% reduction is sufficient to meet the demands of the efficient grain refinement and modification of A356 alloy. When Al-5Ti-B is introduced into the melt prior to degassing, the grain refinement efficiency of Al-5Ti-B will be greatly increased due to the better dispersity of TiB2 particles. Al-5Ti-B master alloy is less prone to affect the modification effect of Al-10Sr when they are used together.

  14. Electrochemistry of cations in diopsidic melt - Determining diffusion rates and redox potentials from voltammetric curves

    Science.gov (United States)

    Colson, Russell O.; Haskin, Larry A.; Crane, Daniel

    1990-01-01

    Results are presented on determinations of reduction potentials and their temperature dependence of selected ions in diopsidic melt, by using linear sweep voltammetry. Diffusion coefficients were measured for cations of Eu, Mn, Cr, and In. Enthalpies and entropies of reduction were determined for the cations V(V), Cr(3+), Mn(2+), Mn(3+), Fe(2+), Cu(2+), Mo(VI), Sn(IV), and Eu(3+). Reduction potentials were used to study the structural state of cations in the melt.

  15. Influence of Reversibly Associating Side Group Bond Strength on Viscoelastic Properties of Polymer Melts

    Science.gov (United States)

    Lewis, Christopher; Stewart, Kathleen; Anthamatten, Mitchell

    2013-03-01

    Reversible hydrogen-bonding between side-groups of linear polymers can sharply influence a material's dynamic mechanical behavior, giving rise to valuable shape memory and self-healing properties. Here, we investigate how bond-strength affects the bulk rheological behavior of functional poly(n-butyl acrylate) (PBA) melts. A series of random copolymers containing three different reversibly bonding groups (aminopyridine, carboxylic acid, and ureidopyrimidinone) were synthesized to systematically vary the side-group hydrogen bond strength (~26, 40, 70 kJ/mol). The materials' volumetric hydrogen-bond energy densities can be tuned by adjusting the side-group composition. By comparing the viscoelastic behavior of materials containing an equivalent bond energy density, with different bonding groups, the efficacy and cooperativity of reversible binding can be directly examined. Melt rheology results are interpreted using a state-of-ease model that assumes continuous mechanical equilibrium between applied stress and resistive stresses of entropic origin arising from a network of reversible bonds. The authors acknowledge support from funding provided by the National Science Foundation under Grant DMR-0906627

  16. Geothermal flux and basal melt rate in the Dome C region inferred from radar reflectivity and heat modelling

    Directory of Open Access Journals (Sweden)

    O. Passalacqua

    2017-09-01

    Full Text Available Basal melt rate is the most important physical quantity to be evaluated when looking for an old-ice drilling site, and it depends to a great extent on the geothermal flux (GF, which is poorly known under the East Antarctic ice sheet. Given that wet bedrock has higher reflectivity than dry bedrock, the wetness of the ice–bed interface can be assessed using radar echoes from the bedrock. But, since basal conditions depend on heat transfer forced by climate but lagged by the thick ice, the basal ice may currently be frozen whereas in the past it was generally melting. For that reason, the risk of bias between present and past conditions has to be evaluated. The objective of this study is to assess which locations in the Dome C area could have been protected from basal melting at any time in the past, which requires evaluating GF. We used an inverse approach to retrieve GF from radar-inferred distribution of wet and dry beds. A 1-D heat model is run over the last 800 ka to constrain the value of GF by assessing a critical ice thickness, i.e. the minimum ice thickness that would allow the present local distribution of basal melting. A regional map of the GF was then inferred over a 80 km  ×  130 km area, with a N–S gradient and with values ranging from 48 to 60 mW m−2. The forward model was then emulated by a polynomial function to compute a time-averaged value of the spatially variable basal melt rate over the region. Three main subregions appear to be free of basal melting, two because of a thin overlying ice and one, north of Dome C, because of a low GF.

  17. Geothermal flux and basal melt rate in the Dome C region inferred from radar reflectivity and heat modelling

    Science.gov (United States)

    Passalacqua, Olivier; Ritz, Catherine; Parrenin, Frédéric; Urbini, Stefano; Frezzotti, Massimo

    2017-09-01

    Basal melt rate is the most important physical quantity to be evaluated when looking for an old-ice drilling site, and it depends to a great extent on the geothermal flux (GF), which is poorly known under the East Antarctic ice sheet. Given that wet bedrock has higher reflectivity than dry bedrock, the wetness of the ice-bed interface can be assessed using radar echoes from the bedrock. But, since basal conditions depend on heat transfer forced by climate but lagged by the thick ice, the basal ice may currently be frozen whereas in the past it was generally melting. For that reason, the risk of bias between present and past conditions has to be evaluated. The objective of this study is to assess which locations in the Dome C area could have been protected from basal melting at any time in the past, which requires evaluating GF. We used an inverse approach to retrieve GF from radar-inferred distribution of wet and dry beds. A 1-D heat model is run over the last 800 ka to constrain the value of GF by assessing a critical ice thickness, i.e. the minimum ice thickness that would allow the present local distribution of basal melting. A regional map of the GF was then inferred over a 80 km × 130 km area, with a N-S gradient and with values ranging from 48 to 60 mW m-2. The forward model was then emulated by a polynomial function to compute a time-averaged value of the spatially variable basal melt rate over the region. Three main subregions appear to be free of basal melting, two because of a thin overlying ice and one, north of Dome C, because of a low GF.

  18. Influence of Pressure Field in Melts on the Primary Nucleation in Solidification Processing

    Science.gov (United States)

    Rakita, Milan; Han, Qingyou

    2017-10-01

    It is well known that external fields applied to melts can cause nucleation at lower supercoolings, fragmentation of growing dendrites, and forced convection around the solidification front. All these effects contribute to a finer microstructure of solidified material. In this article, we analyze how the pressure field created with ultrasonic vibrations influences structure refinement in terms of supercooling. It is shown that only high cavitation pressures of the order of 104 atmospheres are capable of nucleating crystals at minimal supercoolings. We demonstrate the possibility of sononucleation even in superheated liquid. Simulation and experiments with water samples show that very high cavitation pressures occur in a relatively narrow zone where the drive acoustic field has an appropriate combination of pressure amplitude and frequency. In order to accurately predict the microstructure formed by ultrasonically assisted solidification of metals, this article calls for the development of equations of state that would describe the pressure-dependent behavior of molten metals.

  19. Landscape transformation under influence of melting buried ice blocks (North Poland)

    Science.gov (United States)

    Słowiński, Michał; Błaszkiewicz, Mirosław; Brauer, Achim; Noryśkiewicz, Bożena; Ott, Florian; Tyszkowski, Sebastian

    2014-05-01

    The aim of the research was to decipher impacts, how dead ice melting can influence landscape transformation in the Lateglacial and early Holocene in Central Europe. Here, we present the paleoecological results from the middle section of the Wda river located in northern Poland (Central Europe), on the outwash plain formed during the Pomeranian phase of the last (Vistulian) glacial period ca 16,000 14C yrs BP. The Wda river has a typical polygenetic valley in young glacial areas of the northern central European lowlands. We reconstructed environmental changes using biotic proxies (plant macrofossil and pollen analyses) and geomorphological investigations. Abrupt changes in lithology and sediment structures show rapid changes and threshold processes in environmental conditions. The AMS 14C dating of terrestrial plant remains reveals an age for the basal sediments of 11 223 ± 23 cal yr BP coinciding with the Preboreal biozone. The results show the existence of buried ice blocks in northern Poland even at the beginning of the Holocene proving that locally discontinuous permafrost was still present at that time. Our study demonstrates a strong influence of melting buried ice blocks on the geomorphological development, hydrological changes in the catchment, and the biotic environment even in the early Holocene. This study is a contribution to the Virtual Institute of Integrated Climate and Landscape Evolution (ICLEA) of the Helmholtz Association. Financial support by the COST Action ES0907 INTIMATE is gratefully acknowledged. The research was supported by the National Science Centre Poland (grants No. NN 306085037 and NCN 2011/01/B/ST10/07367).

  20. Influence of spring snowpack melting on thunderstorm activity in the Catalan Pyrenees

    Science.gov (United States)

    Pascual, R.; Callado, A.; Terradelles, E.; Téllez, B.

    2009-09-01

    Catalan Pyrenees, the eastern half of the Pyrenees range, is a very popular area for tourism, hiking and climbing. This sector of the range is 200 km long and, on average, 80 km wide. Its highest peaks reach 3000 m ASL and there are many summits above 2500 m ASL. Two of the main climatic characteristics of the region are the very frequent summer convective storms and the late autumn, winter and spring snow-cover. Both characteristics have normally been studied from different points of view, and weather forecasts in late spring have not normally considered the plausible relationship between them. The snowpack melting from April to June, especially rapid in May, leads to important changes on the surface energy balance since the evolution from snow-covered ground to bare soil or canopy, significantly alters the surface albedo and the turbulent, latent and sensible, heat fluxes. These modifications have a noticeable influence in developing or inhibiting thermally-induced mesoscale circulations such as upslope winds, valley breezes or plane-mountain breezes, and could condition the triggering of convection, showers and storm activity. In order to gain insight into the relationship between the spring snowpack melting and the location of thunderstorm activity, a comparison between seasonal snow-cover and thunderstorm frequency evolution (using lightning network data) for a period of 5 years has been carried out, showing a progressive transition from a non-convective to a convective precipitation regime in areas where the snowpack has melted recently Furthermore, a meso-beta scale non-hydrostatic numerical weather prediction model at a 2.5-km horizontal resolution is used to study the sensitivity of snowpack extension on the thunderstorms development over the complex orography of the Catalan Pyrenees. A spring case with thunderstorm activity restricted to snow-free areas has been selected and accurately simulated. A number of sensitivity runs with different initial snow

  1. Influence of Air Temperature Difference on the Snow Melting Simulation of SWAT Model

    Science.gov (United States)

    YAN, Y.; Onishi, T.

    2013-12-01

    The temperature-index models are commonly used to simulate the snowmelt process in mountain areas because of its good performance, low data requirements, and computational simplicity. Widely used distributed hydrological model: Soil and Water Assessment Tool (SWAT) model is also using a temperature-index module. However, the lack of monitoring air temperature data still involves uncertainties and errors in its simulation performance especially in data sparse area. Thus, to evaluate the different air temperature data influence on the snow melt of the SWAT model, five different air temperature data are applied in two different Russia basins (Birobidjan basin and Malinovka basin). The data include the monitoring air temperature data (TM), NCEP reanalysis data (TNCEP), the dataset created by inverse distance weighted interpolation (IDW) method (TIDW), the dataset created by improved IDW method considering the elevation influence (TIDWEle), and the dataset created by using linear regression and MODIS Land Surface Temperature (LST) data (TLST). Among these data, the TLST , the TIDW and TIDWEle data have the higher spatial density, while the TNCEP and TM DATA have the most valid monitoring value for daily scale. The daily simulation results during the snow melting seasons (March, April and May) showed reasonable results in both test basins for all air temperature data. While R2 and NSE in Birobidjan basin are around 0.6, these values in Malinovka basin are over 0.75. Two methods: Generalized Likelihood Uncertainty Estimation (GLUE) and Sequential Uncertainty Fitting, version. 2 (SUFI-2) were used for model calibration and uncertainty analysis. The evolution index is p-factor which means the percentage of measured data bracketed by the 95% Prediction Uncertainty (95PPU). The TLST dataset always obtained the best results in both basins compared with other datasets. On the other hand, the two IDW based method get the worst results among all the scenarios. Totally, the

  2. Superheating and melting within aluminum core-oxide shell nanoparticles for a broad range of heating rates: multiphysics phase field modeling.

    Science.gov (United States)

    Hwang, Yong Seok; Levitas, Valery I

    2016-10-19

    The external surface of metallic particles is usually covered by a thin and strong oxide shell, which significantly affects superheating and melting of particles. The effects of geometric parameters and heating rate on characteristic melting and superheating temperatures and melting behavior of aluminum nanoparticles covered by an oxide shell were studied numerically. For this purpose, the multiphysics model that includes the phase field model for surface melting, a dynamic equation of motion, a mechanical model for stress and strain simulations, interface and surface stresses, and the thermal conduction model including thermoelastic and thermo-phase transformation coupling as well as transformation dissipation rate was formulated. Several nontrivial phenomena were revealed. In comparison with a bare particle, the pressure generated in a core due to different thermal expansions of the core and shell and transformation volumetric expansion during melting, increases melting temperatures with the Clausius-Clapeyron factor of 60 K GPa(-1). For the heating rates Q ≤ 10(9) K s(-1), melting temperatures (surface and bulk start and finish melting temperatures, and maximum superheating temperature) are independent of Q. For Q ≥ 10(12) K s(-1), increasing Q generally increases melting temperatures and temperature for the shell fracture. Unconventional effects start for Q ≥ 10(12) K s(-1) due to kinetic superheating combined with heterogeneous melting and geometry. The obtained results are applied to shed light on the initial stage of the melt-dispersion-mechanism of the reaction of Al nanoparticles. Various physical phenomena that promote or suppress melting and affect melting temperatures and temperature of the shell fracture for different heating-rate ranges are summarized in the corresponding schemes.

  3. Influence of melt convection on the interface during Czochralski crystal growth

    Science.gov (United States)

    Miller, W.; Rehse, U.; Böttcher, K.

    2000-05-01

    During the growth process of single bulk crystals from melt, the defect density is strongly affected by the shape of the melt/crystal interface. The shape of the interface is governed by the construction of the growth equipment including the heating system and the convection in the melt. In this paper the flow in a GaAs melt and the boron oxide encapsulant in an equipment used for vapour pressure controlled Czochralski growth has been calculated. 2D-axisymmetric calculations have been performed by using the commercial general purpose program FIDAP TM. A simple model has been developed to describe the phase change problem in the weak form.

  4. ROLE OF MANGANESE REDUCTION/OXIDATION (REDOX) ON FOAMING AND MELT RATE IN HIGH LEVEL WASTE (HLW) MELTERS (U)

    Energy Technology Data Exchange (ETDEWEB)

    Jantzen, C; Michael Stone, M

    2007-03-30

    High-level nuclear waste is being immobilized at the Savannah River Site (SRS) by vitrification into borosilicate glass at the Defense Waste Processing Facility (DWPF). Control of the Reduction/Oxidation (REDOX) equilibrium in the DWPF melter is critical for processing high level liquid wastes. Foaming, cold cap roll-overs, and off-gas surges all have an impact on pouring and melt rate during processing of high-level waste (HLW) glass. All of these phenomena can impact waste throughput and attainment in Joule heated melters such as the DWPF. These phenomena are caused by gas-glass disequilibrium when components in the melter feeds convert to glass and liberate gases such as H{sub 2}O vapor (steam), CO{sub 2}, O{sub 2}, H{sub 2}, NO{sub x}, and/or N{sub 2}. During the feed-to-glass conversion in the DWPF melter, multiple types of reactions occur in the cold cap and in the melt pool that release gaseous products. The various gaseous products can cause foaming at the melt pool surface. Foaming should be avoided as much as possible because an insulative layer of foam on the melt surface retards heat transfer to the cold cap and results in low melt rates. Uncontrolled foaming can also result in a blockage of critical melter or melter off-gas components. Foaming can also increase the potential for melter pressure surges, which would then make it difficult to maintain a constant pressure differential between the DWPF melter and the pour spout. Pressure surges can cause erratic pour streams and possible pluggage of the bellows as well. For these reasons, the DWPF uses a REDOX strategy and controls the melt REDOX between 0.09 {le} Fe{sup 2+}/{summation}Fe {le} 0.33. Controlling the DWPF melter at an equilibrium of Fe{sup +2}/{summation}Fe {le} 0.33 prevents metallic and sulfide rich species from forming nodules that can accumulate on the floor of the melter. Control of foaming, due to deoxygenation of manganic species, is achieved by converting oxidized MnO{sub 2} or Mn

  5. The influence of chain stretching on the phase behavior of multiblock copolymer and comb copolymer melts

    NARCIS (Netherlands)

    Angerman, HJ; ten Brinke, G

    The subject of this paper is inspired by microphase-separated copolymer melts in which a small-scale structure is present inside one of the phases of a large-scale structure. Such a situation can arise in a diblock copolymer melt, if one of the blocks of the diblock is in itself a multiblock

  6. The influence of chain stretching on the phase behavior of multiblock copolymer and comb copolymer melts

    NARCIS (Netherlands)

    Angerman, HJ; ten Brinke, G

    2003-01-01

    The subject of this paper is inspired by microphase-separated copolymer melts in which a small-scale structure is present inside one of the phases of a large-scale structure. Such a situation can arise in a diblock copolymer melt, if one of the blocks of the diblock is in itself a multiblock copolym

  7. Influence of the oxygen partial pressure on the phase evolution during Bi-2212 wire melt processing

    CERN Document Server

    C. Scheuerlein; M.O. Rikel; J. Kadar; C. Doerrer; M. Di Michiel; A. Ballarino; L. Bottura; J. Jiang; F. Kametani; E.E. Hellstrom; D.C. Larbalestier; 10.1109/TASC.2016.2533574

    2016-01-01

    We have studied the influence of the oxygen partial pressure pO2 up to 5.5 bar on the phase changes that occur during melt processing of a state-of-the-art Bi-2212 multifilamentary wire. Phase changes have been monitored in situ by high energy synchrotron X-ray diffraction (XRD). We found that the stability of Bi-2212 phase is reduced with increasing pO2. For pO2>1 bar a significant amount of Bi-2212 phase decomposes upon heating in the range 400 to 650 °C. The extent of decomposition strongly increases with increasing pO2, and at pO2=5.5 bar Bi-2212 decomposes completely in the solid state. Textured Bi-2212 can be formed during solidification when pO2 is reduced to 0.45 bar when the precursor is molten. Since the formation of current limiting second phases is very sensitive to pO2 when it exceeds 1 bar, we recommend to reduce the oxygen partial pressure below the commonly used pO2=1 bar, in order to increase the pO2 margins and to make the overpressure process more robust.

  8. Influence of temperature and chemical composition on phase transformations of selected oxide melts

    Directory of Open Access Journals (Sweden)

    J. Dobrovská

    2013-07-01

    Full Text Available The paper deals with structural changes of solid phase of selected oxide systems during their transition into liquid state. Analyses concerned poly-component systems forming basis of casting powders for CCM mould. Industrially used oxide system with prevailing contents of CaO–Al2O3–SiO2 components and with numerous accompanying admixtures was tested. Investigation was focused on temperatures, during which individual phases disappear and precipitate, as well as on influence of CaO content on phase composition at selected temperatures. The experiments were realised with use of original methodology consisting of shock cooling of the tested melt in liquid nitrogen. Thus obtained samples were further investigated by X-ray diffraction phase analyses at ambient temperatures. The obtained results provide additional data on physical-chemical properties of oxide systems, such as surface tension, viscosity, sintering intervals, etc., which can be used in technological practice for appropriate lubrication effect of casting powders in the mould.

  9. Characterization of mesostasis regions in lunar basalts: Understanding late-stage melt evolution and its influence on apatite formation

    Science.gov (United States)

    Potts, Nicola J.; TartèSe, Romain; Anand, Mahesh; Westrenen, Wim; Griffiths, Alexandra A.; Barrett, Thomas J.; Franchi, Ian A.

    2016-09-01

    Recent studies geared toward understanding the volatile abundances of the lunar interior have focused on the volatile-bearing accessory mineral apatite. Translating measurements of volatile abundances in lunar apatite into the volatile inventory of the silicate melts from which they crystallized, and ultimately of the mantle source regions of lunar magmas, however, has proved more difficult than initially thought. In this contribution, we report a detailed characterization of mesostasis regions in four Apollo mare basalts (10044, 12064, 15058, and 70035) in order to ascertain the compositions of the melts from which apatite crystallized. The texture, modal mineralogy, and reconstructed bulk composition of these mesostasis regions vary greatly within and between samples. There is no clear relationship between bulk-rock basaltic composition and that of bulk-mesostasis regions, indicating that bulk-rock composition may have little influence on mesostasis compositions. The development of individual melt pockets, combined with the occurrence of silicate liquid immiscibility, exerts greater control on the composition and texture of mesostasis regions. In general, the reconstructed late-stage lunar melts have roughly andesitic to dacitic compositions with low alkali contents, displaying much higher SiO2 abundances than the bulk compositions of their host magmatic rocks. Relevant partition coefficients for apatite-melt volatile partitioning under lunar conditions should, therefore, be derived from experiments conducted using intermediate compositions instead of compositions representing mare basalts.

  10. NanoSIMS results from olivine-hosted melt embayments: Magma ascent rate during explosive basaltic eruptions

    Science.gov (United States)

    Lloyd, Alexander S.; Ruprecht, Philipp; Hauri, Erik H.; Rose, William; Gonnermann, Helge M.; Plank, Terry

    2014-08-01

    The explosivity of volcanic eruptions is governed in part by the rate at which magma ascends and degasses. Because the time scales of eruptive processes can be exceptionally fast relative to standard geochronometers, magma ascent rate remains difficult to quantify. Here we use as a chronometer concentration gradients of volatile species along open melt embayments within olivine crystals. Continuous degassing of the external melt during magma ascent results in diffusion of volatile species from embayment interiors to the bubble located at their outlets. The novel aspect of this study is the measurement of concentration gradients in five volatile elements (CO2, H2O, S, Cl, F) at fine-scale (5-10 μm) using the NanoSIMS. The wide range in diffusivity and solubility of these different volatiles provides multiple constraints on ascent timescales over a range of depths. We focus on four 100-200 μm, olivine-hosted embayments erupted on October 17, 1974 during the sub-Plinian eruption of Volcán de Fuego. H2O, CO2, and S all decrease toward the embayment outlet bubble, while F and Cl increase or remain roughly constant. Compared to an extensive melt inclusion suite from the same day of the eruption, the embayments have lost both H2O and CO2 throughout the entire length of the embayment. We fit the profiles with a 1-D numerical diffusion model that allows varying diffusivities and external melt concentrations as a function of pressure. Assuming a constant decompression rate from the magma storage region at approximately 220 MPa to the surface, H2O, CO2 and S profiles for all embayments can be fit with a relatively narrow range in decompression rates of 0.3-0.5 MPa/s, equivalent to 11-17 m/s ascent velocity and an 8 to 12 minute duration of magma ascent from ~ 10 km depth. A two stage decompression model takes advantage of the different depth ranges over which CO2 and H2O degas, and produces good fits given an initial stage of slow decompression (0.05-0.3 MPa/s) at high

  11. Influence of surface roughness and melt superheat on HDA process to form a tritium permeation barrier on RAFM steel

    Energy Technology Data Exchange (ETDEWEB)

    Purushothaman, J. [B.S. Abdur Rahman University, Chennai 600048 (India); MTD, MMG, IGCAR, Kalpakkam 603102 (India); Ramaseshan, R., E-mail: seshan@igcar.gov.in [TFCS, SND, MSG, IGCAR, Kalpakkam 603102 (India); Albert, S.K. [MTD, MMG, IGCAR, Kalpakkam 603102 (India); Rajendran, R. [B.S. Abdur Rahman University, Chennai 600048 (India); Gowrishankar, N. [IP Rings Ltd., Maraimalainagar, Chennai 603209 (India); Ramasubbu, V. [MTD, MMG, IGCAR, Kalpakkam 603102 (India); Murugesan, S.; Dasgupta, Arup [PMG, MMG, IGCAR, Kalpakkam 603102 (India); Jayakumar, T. [MTD, MMG, IGCAR, Kalpakkam 603102 (India)

    2015-12-15

    Highlights: • Surface modified RAFMS samples were subjected to HDA and thermal oxidation. • Sample modified by SB process showed better coating and interface morphology. • Aluminized samples at 740 °C for 2 min showed Fe{sub 2}Al{sub 9}Si{sub 2} intermetallic phase. • Oxidized samples showed Fe{sub 2}Al{sub 8}Si, Fe{sub 2}Al{sub 3}Si{sub 3} and Fe{sub 3}Al{sub 2}Si{sub 3} intermetallic phases. • A uniform permeation barrier Al{sub 2}O{sub 3} was formed on the coating of oxidized HDA samples. - Abstract: The most optimal candidate material for fabrication of Test Blanket Module (TBM) in the installation of ITER and future fusion reactors is Reduced Activation Ferritic Martensitic (RAFM) steel, yet one of the major challenges that need to be addressed with RAFM is minimizing the loss of tritium in a reactor environment through the formation of tritium permeation barrier. One of the most promising methods for the tritium permeation barrier is through duplex coating with Al{sub 2}O{sub 3}/Fe–Al which is well known to reduce tritium permeation rate by several orders of magnitude. The present work aims to form an alumina layer on RAFM steel by a two-step method, which consists of (i) Hot Dip Aluminizing (HDA) and (ii) conversion of Al into alumina by a subsequent oxidation process. In addition, the influence of surface roughness of the substrate, superheat condition of the Al alloy melt and its composition on microstructural properties of coating before and after oxidation were investigated using OM, SEM–EDS, XRD, indentation micro hardness and scratch test. The experimental results confirmed the formation of alumina layer on RAFM steel after the HDA and oxidation process. Moreover, the surface roughness of the substrate, melt superheat of Al alloy and its composition are found to have a significant influence on the microstructure, thickness, micro-hardness, nature of intermetallic compounds formed and adhesion strength of the coating.

  12. Influence of Annealing on Mechanical Properties of Al-20Si Processed by Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Pan Ma

    2014-01-01

    Full Text Available The microstructure and mechanical properties of Al-20Si produced by selective laser melting (SLM are investigated for different heat treatment conditions. As a result of the high cooling rate during processing, the as-built SLM material displays a microstructure consisting of a supersaturated Al(Si solid solution along with heavily refined eutectic Si and Si particles. The Si particles become coarser, and the eutectic Si gradually changes its morphology from fibrous to plate-like shape with increasing annealing temperature. The microstructural variations occurring during heat treatment significantly affect the mechanical behavior of the samples. The yield and ultimate strengths decrease from 374 and 506 MPa for the as-built SLM material to 162 and 252 MPa for the sample annealed at 673 K, whereas the ductility increases from 1.6 to 8.7%. This offers the possibility to tune microstructure and corresponding properties of the Al-20Si SLM parts to meet specific requirements.

  13. Alcohol dose dumping: The influence of ethanol on hot-melt extruded pellets comprising solid lipids.

    Science.gov (United States)

    Jedinger, N; Schrank, S; Mohr, S; Feichtinger, A; Khinast, J; Roblegg, E

    2015-05-01

    The objective of the present study was to investigate interactions between alcohol and hot-melt extruded pellets and the resulting drug release behavior. The pellets were composed of vegetable calcium stearate as matrix carrier and paracetamol or codeine phosphate as model drugs. Two solid lipids (Compritol® and Precirol®) were incorporated into the matrix to form robust/compact pellets. The drug release characteristics were a strong function of the API solubility, the addition of solid lipids, the dissolution media composition (i.e., alcohol concentration) and correspondingly, the pellet wettability. Pellets comprising paracetamol, which is highly soluble in ethanol, showed alcohol dose dumping regardless of the matrix composition. The wettability increased with increasing ethanol concentrations due to higher paracetamol solubilities yielding increased dissolution rates. For pellets containing codeine phosphate, which has a lower solubility in ethanol than in acidic media, the wettability was a function of the matrix composition. Dose dumping occurred for formulations comprising solid lipids as they showed increased wettabilities with increasing ethanol concentrations. In contrast, pellets comprising calcium stearate as single matrix component showed robustness in alcoholic media due to wettabilities that were not affected by the addition of ethanol. The results clearly indicate that the physico-chemical properties of the drug and the matrix systems are crucial for the design of ethanol-resistant dosage forms. Moreover, hydrophobic calcium stearate can be considered a suitable matrix system that minimizes the risk of ethanol-induced dose dumping for certain API's.

  14. Influence of element Cu on hydrogen content in superheated aluminum melt

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The hydrogen content in molten Al-Cu alloy increases remarkably when the temperature of the melt rises to about 780  ℃. The effects of alloying element are theoretically analyzed in terms of Wagner interaction parameter. Furthermore, analyses indicate that the alloy element Cu plays an important role in the hydrogen content in superheated Al-Cu alloy melt below about 780  ℃. The conclusion is drawn that the degree of gassing in molten Al-Cu alloy is bound up with the properties of oxide film of Al alloy melts. The results make it clear that the hydrogen content in the molten aluminum reduces with increasing element Cu dissolved in aluminum melts at the same temperature.

  15. Influence of melt annealing on rheological and electrical properties of compatibilized multiwalled carbon nanotubes in polypropylene

    Science.gov (United States)

    Nasti, Giuseppe; Ambrogi, Veronica; Cerruti, Pierfrancesco; Gentile, Gennaro; Di Maio, Rosa; Carfagna, Cosimo

    2014-05-01

    Pristine and surface functionalized multiwalled carbon nanotubes (MWCNT) were melt mixed with a polypropylene (PP) polymer matrix. Rheology, morphology, electrical conductivity and mechanical properties of the nanocomposites were evaluated for different MWCNT loadings. Melt annealing effect on properties was also investigated. It was found that both surface functionalization of MWCNT and thermal annealing were able to favor a better dispersion of the particles, inducing the formation of a percolative network.

  16. Enhancement of the dissolution rate and bioavailability of fenofibrate by a melt-adsorption method using supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Cha KH

    2012-10-01

    Full Text Available Kwang-Ho Cha,1,3 Kyung-Jin Cho,3 Min-Soo Kim,4 Jeong-Soo Kim,3 Hee Jun Park,1,3 Junsung Park,1,3 Wonkyung Cho,1,3 Jeong-Sook Park,3 Sung-Joo Hwang1,21Yonsei Institute of Pharmaceutical Sciences, 2College of Pharmacy, Yonsei University, Incheon, Republic of Korea; 3College of Pharmacy, Chungnam National University, Daejeon, Republic of Korea; 4Department of Pharmaceutical Engineering, Inje University, Gimhae, Republic of KoreaBackground: The aim of this study was to enhance the bioavailability of fenofibrate, a poorly water-soluble drug, using a melt-adsorption method with supercritical CO2.Methods: Fenofibrate was loaded onto Neusilin® UFL2 at different weight ratios of fenofibrate to Neusilin UFL2 by melt-adsorption using supercritical CO2. For comparison, fenofibrate-loaded Neusilin UFL2 was prepared by solvent evaporation and hot melt-adsorption methods. The fenofibrate formulations prepared were characterized by differential scanning calorimetry, powder x-ray diffractometry, specific surface area, pore size distribution, scanning electron microscopy, and energy-dispersive x-ray spectrometry. In vitro dissolution and in vivo bioavailability were also investigated.Results: Fenofibrate was distributed into the pores of Neusilin UFL2 and showed reduced crystal formation following adsorption. Supercritical CO2 facilitated the introduction of fenofibrate into the pores of Neusilin UFL2. Compared with raw fenofibrate, fenofibrate from the prepared powders showed a significantly increased dissolution rate and better bioavailability. In particular, the area under the drug concentration-time curve and maximal serum concentration of the powders prepared using supercritical CO2 were 4.62-fold and 4.52-fold greater than the corresponding values for raw fenofibrate.Conclusion: The results of this study highlight the usefulness of the melt-adsorption method using supercritical CO2 for improving the bioavailability of fenofibrate.Keywords: fenofibrate

  17. 融雪剂对地表水及地下水的影响%The Influence of Snow-melting Agent on Surface Water and Groundwater

    Institute of Scientific and Technical Information of China (English)

    蔡雯璐

    2011-01-01

    The changes of aquatic environment after using snow-melting agent on highway are studied by detecting the relevant indexes of surface water and groundwater samples.The result shows that: the using of snow-melting agent increases the content of chlorine ion and other relevant metal salt ions in surface water and groundwater,among which surface water is influenced more seriously by snow-melting agent and the highest increasing rate of chloride content is 56.77%.%通过对地表水和地下水样品相关指标进行检测,对公路在使用融雪剂后水体环境的变化情况进行研究。结果表明:融雪剂的使用提高了地表水和地下水中的氯离子和其它相关金属盐离子的含量。其中地表水受融雪剂影响较大,氯化物含量增加率最高为56.77%。

  18. Influence of Elemental Iron on Hydrogen Content in Superheated Aluminum-iron Melts

    Institute of Scientific and Technical Information of China (English)

    HU Li-na; BIAN Xiu-fang; ANANDA Mahto; DUAN You-feng

    2004-01-01

    The hydrogen content in liquid binary aluminum alloys with 1,3,5 and 8 wt% iron has been determined in the temperature range from 973K to 1103K.The hydrogen content in molten Al-Fe alloys increases remarkably when the temperature of the melt rises to about 1053K.This work indicates that the alloying element iron plays an important role in hydrogen content in superheated Al-Fe alloy melts below about 1053K.The results make it clear that the hydrogen content in the melt aluminum reduces with the increasing element levels.A conclusion is drawn that the degree of gassing in molten Al-Fe alloys is bound up with the properties of oxide film of aluminum alloy melts.The element iron has no effect on the compact structure of oxide film in aluminum melts.The effects of alloying element are theoretically analyzed in terms of Wagner interaction parameter.According to the values of the first order interaction parameter,it is concluded that the interaction between iron atom and aluminum is much stronger than that between hydrogen atom and aluminum,and the addition of the alloying element decreases the affinity of liquid aluminum for hydrogen.

  19. Evidence of refilled chamber gas pressure enhancing cooling rate during melt spinning of a Zr50Cu40Al10 alloy

    Institute of Scientific and Technical Information of China (English)

    Hong-wang Yang; Peng Zhang; M J Tan; Yuan Ge; Wan-ping Tian; Rui-chun Wang; Rong-de Li

    2015-01-01

    The inlfuence of the reifl ed gas pressure on the glass forming behaviour of one of the best ternary glass forming al oys Zr50Cu40Al10 was studied for the melt spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The reifl ed chamber atmospheric pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.0001 atm, ful y crystal ine fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1 atm or higher. The extended contact length between thecribbons and the copper wheel contributes to the high cooling rate of melt spinning. Higher chamber gas pressure leads to more turbulence of liquid metal beneath the nozzle;therefore, lower pressure is preferable at practical melt spinning processes once glass forming conditions are fulifl ed.

  20. Possible long-term decline in impact rates. 2. Lunar impact-melt data regarding impact history

    Science.gov (United States)

    Hartmann, William K.; Quantin, Cathy; Mangold, Nicolas

    2007-01-01

    Crater counts at lunar landing sites with measured ages establish a steep decline in cratering rate during the period ˜3.8 to ˜3.1 Gyr ago. Most models of the time dependence suggest a roughly constant impact rate (within factor ˜2) after about 3 Gyr ago, but are based on sparse data. Recent dating of impact melts from lunar meteorites, and Apollo glass spherules, clarifies impact rates from ˜3.2 to ˜2 Gyr ago or less. Taken together, these data suggest a decline with roughly 700 Myr half-life around 3 Gyr ago, and a slower decline after that, dropping by a factor ˜3 from about ˜2.3 Gyr ago until the present. Planetary cratering involved several phases with different time behaviors: (1) rapid sweep-up of most primordial planetesimals into planets in the first hundred Myr, (2) possible later effects of giant planet migration with enhanced cratering, (3) longer term sweep-up of leftover planetesimals, and finally (4) the present long-term "leakage" of asteroids from reservoirs such as the main asteroid belt and Kuiper belt. In addition, at any given point on the Moon, a pattern of "spikes" (sharp maxima of relatively narrow time width) will appear in the production rate of smaller craters (≲500 m?), not only from secondary debris from large primary lunar impacts at various distances from the point in question, but also from asteroid breakups dotted through Solar System history. The pattern of spikes varies according to type of sample being measured (i.e., glass spherules vs impact melts). For example, several data sets show an impact rate spike ˜470 Myr ago associated with the asteroid belt collision that produced the L chondrites (see Section 3.6 below). Such spikes should be less prominent in the production record of craters of D≳ few km. These phenomena affect estimates of planetary surfaces ages from crater counts, as discussed in a companion paper [Quantin, C., Mangold, N., Hartmann, W.K., Allemand, P., 2007. Icarus 186, 1-10]. Fewer impact melts and

  1. Influence of snowpack internal structure on snow metamorphism and melting intensity on Hansbreen, Svalbard

    Directory of Open Access Journals (Sweden)

    Laska Michał

    2016-06-01

    Full Text Available This paper presents a detailed study of melting processes conducted on Hansbreen – a tidewater glacier terminating in the Hornsund fjord, Spitsbergen. The fieldwork was carried out from April to July 2010. The study included observations of meltwater distribution within snow profiles in different locations and determination of its penetration time to the glacier ice surface. In addition, the variability of the snow temperature and heat transfer within the snow cover were measured. The main objective concerns the impact of meltwater on the diversity of physical characteristics of the snow cover and its melting dynamics. The obtained results indicate a time delay between the beginning of the melting processes and meltwater reaching the ice surface. The time necessary for meltwater to percolate through the entire snowpack in both, the ablation zone and the equilibrium line zone amounted to c. 12 days, despite a much greater snow depth at the upper site. An elongated retention of meltwater in the lower part of the glacier was caused by a higher amount of icy layers (ice formations and melt-freeze crusts, resulting from winter thaws, which delayed water penetration. For this reason, a reconstruction of rain-on-snow events was carried out. Such results give new insight into the processes of the reactivation of the glacier drainage system and the release of freshwater into the sea after the winter period.

  2. The influence of melting on the kinematic development of the Himalayan crystalline core

    Science.gov (United States)

    Webb, Alexander

    2016-04-01

    Current hypotheses for the development and emplacement of the Himalayan crystalline core are 1) models with intense upper plate out-of-sequence activity (i.e., tunneling of channel flow, and some modes of critical taper wedge behavior) and 2) models in which the upper plate mainly records basal accretion of horses (i.e., duplexing). The two concepts can be considered end-members. A signal difference between these two models is the role of melting. The intense upper plate deformation envisioned in the first set of models has been hypothesized to be largely a product of partial melting, particularly in channel flow models. Specifically, the persistent presence of melt in the middle crust of the upper plate may dramatically lower the viscosity of these rocks, allowing distributed deformation. The second set of models - duplexing - predicts in-sequence thrusting with only minor out-of-sequence deformation. Stacking of a duplex acts like a deli cheese-slicing machine: slice after slice is cut from the intact block to a stack of slices, but neither the block (~down-going plate) nor the stack (~upper plate) features much internal deformation. In this model, partial melting produces no significant kinematic impact. The dominant preserved structural elements across the Himalayan crystalline core rocks are flattening and L-S fabrics. Structurally high portions of the crystalline core locally display complex outcrop-scale deformation associated with migmatitic rocks, and contain km-scale leucogranite bodies; both features developed in the early to middle Miocene. The flattening and L-S fabrics have been interpreted to record either (A) southwards channel tunneling across the upper plate, or (B) fabric development during metamorphism of the down-going plate, prior to accretion to the upper plate. The deformation of migmatitic rock and emplacement of leucogranite have been interpreted in support of widespread distributed deformation. Alternatively, these features may have

  3. Spatiotemporal tracer variability in glacier melt and its influence on hydrograph separation

    Science.gov (United States)

    Schmieder, Jan; Marke, Thomas; Strasser, Ulrich

    2017-04-01

    Glaciers are important seasonal water contributors in many mountainous regions. Knowledge on the timing and amount of glacier melt water is crucial for water resources management, especially in downstream regions where the water is needed (hydropower, drinking water) or where it represents a potential risk (drought, flood). This becomes even more relevant in a changing climate. Environmental tracers are a useful tool in the assessment of ice water resources, because they provide information about the sources, flow paths and traveling times of water contributing to streamflow at the catchment scale. Hydrometric and meteorological measurements combined with tracer analyses help to unravel streamflow composition and improve the understanding of hydroclimatological processes. Empirical studies on runoff composition are necessary to parameterize and validate hydrological models in a process-oriented manner, rather than comparing total measured and simulated runoff only. In the present study three approaches of hydrograph separation are compared to decide which sampling frequency is required to capture the spatiotemporal variability of glacier melt, and to draw implications for future studies of streamflow partitioning. Therefore glacier melt contributions to a proglacial stream at the sub-daily, daily, and seasonal scale were estimated using electrical conductivity and oxygen-18 as tracers. The field work was conducted during December 2015 and September 2016 in the glaciated (34%) high-elevation catchment of the Hochjochbach, a small sub-basin (17 km2) of the Oetztaler Ache river in the Austrian Alps, ranging from 2400 to 3500 m a.s.l. in elevation. Hydroclimatological data was provided by an automatic weather station and a streamflow gauging station equipped with a pressure transducer. Water samples of streamflow, glacier melt, and rain were collected throughout the winter period (December to March) and the ablation season (July to September). In the proposed

  4. Continuous melt granulation: Influence of process and formulation parameters upon granule and tablet properties.

    Science.gov (United States)

    Monteyne, Tinne; Vancoillie, Jochem; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-01

    The pharmaceutical industry has a growing interest in alternative manufacturing models allowing automation and continuous production in order to improve process efficiency and reduce costs. Implementing a switch from batch to continuous processing requires fundamental process understanding and the implementation of quality-by-design (QbD) principles. The aim of this study was to examine the relationship between formulation-parameters (type binder, binder concentration, drug-binder miscibility), process-parameters (screw speed, powder feed rate and granulation temperature), granule properties (size, size distribution, shape, friability, true density, flowability) and tablet properties (tensile strength, friability, dissolution rate) of four different drug-binder formulations using Design of experiments (DOE). Two binders (polyethylene glycol (PEG) and Soluplus®) with a different solid state, semi-crystalline vs amorphous respectively, were combined with two model-drugs, metoprolol tartrate (MPT) and caffeine anhydrous (CAF), both having a contrasting miscibility with the binders. This research revealed that the granule properties of miscible drug-binder systems depended on the powder feed rate and barrel filling degree of the granulator whereas the granule properties of immiscible systems were mainly influenced by binder concentration. Using an amorphous binder, the tablet tensile strength depended on the granule size. In contrast, granule friability was more important for tablet quality using a brittle binder. However, this was not the case for caffeine-containing blends, since these phenomena were dominated by the enhanced compression properties of caffeine Form I, which was formed during granulation. Hence, it is important to gain knowledge about formulation behavior during processing since this influences the effect of process parameters onto the granule and tablet properties.

  5. Gauging Media Influence on Adolescent Suicide Rates

    Science.gov (United States)

    Siegel, Darren; McCabe, Paul C.

    2009-01-01

    The "Morbidity and Mortality Weekly Report" published by the Centers for Disease Control (CDC) reported that in 2004, suicide was the third leading cause of death among 10- to 24-year olds and accounted for 4,599 deaths. From 2003 to 2004, suicide rates of females age 10-14 years and 15-19 years and males age 15-19 years increased significantly.…

  6. The influence of laser re-melting on microstructure and hardness of gas-nitrided steel

    Directory of Open Access Journals (Sweden)

    Panfil Dominika

    2016-12-01

    Full Text Available In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, ε+γ’ compound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser remelted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P, ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

  7. MELT RATE ENHANCEMENT FOR HIGH ALUMINUM HLW (HIGH LEVEL WASTE) GLASS FORMULATION FINAL REPORT 08R1360-1

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; MATLACK KS; KOT W; PEGG IL; JOSEPH I; BARDAKCI T; GAN H; GONG W; CHAUDHURI M

    2010-01-04

    This report describes the development and testing of new glass formulations for high aluminum waste streams that achieve high waste loadings while maintaining high processing rates. The testing was based on the compositions of Hanford High Level Waste (HLW) with limiting concentrations of aluminum specified by the Office of River Protection (ORP). The testing identified glass formulations that optimize waste loading and waste processing rate while meeting all processing and product quality requirements. The work included preparation and characterization of crucible melts and small scale melt rate screening tests. The results were used to select compositions for subsequent testing in a DuraMelter 100 (DM100) system. These tests were used to determine processing rates for the selected formulations as well as to examine the effects of increased glass processing temperature, and the form of aluminum in the waste simulant. Finally, one of the formulations was selected for large-scale confirmatory testing on the HLW Pilot Melter (DM1200), which is a one third scale prototype of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) HLW melter and off-gas treatment system. This work builds on previous work performed at the Vitreous State Laboratory (VSL) for Department of Energy (DOE) to increase waste loading and processing rates for high-iron HLW waste streams as well as previous tests conducted for ORP on the same high-aluminum waste composition used in the present work and other Hanford HLW compositions. The scope of this study was outlined in a Test Plan that was prepared in response to an ORP-supplied statement of work. It is currently estimated that the number of HLW canisters to be produced in the WTP is about 13,500 (equivalent to 40,500 MT glass). This estimate is based upon the inventory of the tank wastes, the anticipated performance of the sludge treatment processes, and current understanding of the capability of the borosilicate glass waste form

  8. Influence of buffer species on the thermodynamics of short DNA duplex melting: sodium phosphate versus sodium cacodylate.

    Science.gov (United States)

    Alemayehu, Saba; Fish, Daniel J; Brewood, Greg P; Horne, M Todd; Manyanga, Fidelis; Dickman, Rebekah; Yates, Ian; Benight, Albert S

    2009-03-05

    Thermodynamic parameters of the melting transitions of 53 short duplex DNAs were experimentally evaluated by differential scanning calorimetry melting curve analysis. Solvents for the DNA solutions contained approximately 1 M Na+ and either 10 mM cacodylate or phosphate buffer. Thermodynamic parameters obtained in the two solvent environments were compared and quantitatively assessed. Thermodynamic stabilities (deltaG(o) (25 degrees C)) of the duplexes studied ranged from quite stable perfect match duplexes (approximately -30 kcal/mol) to relatively unstable mismatch duplexes (approximately -9 kcal/mol) and ranged in length from 18 to 22 basepairs. A significant difference in stability (average free energy difference of approximately 3 kcal/mol) was found for all duplexes melted in phosphate (greater stability) versus cacodylate buffers. Measured effects of buffer species appear to be relatively unaffected by duplex length or sequence content. The popular sets of published nearest-neighbor (n-n) stability parameters for Watson-Crick (w/c) and single-base mismatches were evaluated from melting studies performed in cacodylate buffer (SantaLucia and Hicks, Annu. Rev. Biophys. Biomol. Struct. 2004, 33, 415). Thus, when using these parameters to make predictions of sequence dependent stability of DNA oligomers in buffers other than cacodylate (e.g., phosphate) one should be mindful that in addition to sodium ion concentration, the type of buffer species also provides a minor but significant contribution to duplex stability. Such considerations could potentially influence results of sequence dependent analysis using published n-n parameters and impact results of thermodynamic calculations. Such calculations and analyses are typically employed in the design and interpretation of DNA multiplex hybridization experiments.

  9. Amundsen Sea sector ice shelf thickness, melt rates, and inland response from annual high-resolution DEM mosaics

    Science.gov (United States)

    Shean, D. E.; Joughin, I. R.; Smith, B. E.; Alexandrov, O.; Moratto, Z.; Porter, C. C.; Morin, P. J.

    2014-12-01

    Significant grounding line retreat, acceleration, and thinning have occurred along the Amundsen Sea sector of West Antarctica in recent decades. These changes are driven primarily by ice-ocean interaction beneath ice shelves, but existing observations of the spatial distribution, timing, and magnitude of ice shelf melt are limited. Using the NASA Ames Stereo Pipeline, we generated digital elevation models (DEMs) with ~2 m posting from all ~450 available WorldView-1/2 along-track stereopairs for the Amundsen Sea sector. A novel iterative closest point algorithm was used to coregister DEMs to filtered Operation IceBridge ATM/LVIS data and ICESat-1 GLAS data, offering optimal sub-meter horizontal/vertical accuracy. The corrected DEMs were used to produce annual mosaics for the entire ~500x700 km region with focused, sub-annual products for ice shelves and grounding zones. These mosaics provide spatially-continuous measurements of ice shelf topography with unprecedented detail. Using these data, we derive estimates of ice shelf thickness for regions in hydrostatic equilibrium and map networks of sub-shelf melt channels for the Pine Island (PIG), Thwaites, Crosson, and Dotson ice shelves. We also document the break-up of the Thwaites ice shelf and PIG rift evolution leading up to the 2013 calving event. Eulerian difference maps document 2010-2014 thinning over fast-flowing ice streams and adjacent grounded ice. These data reveal the greatest thinning rates over the Smith Glacier ice plain and slopes beyond the margins of the fast-flowing PIG trunk. Difference maps also highlight the filling of at least two subglacial lakes ~30 km upstream of the PIG grounding line in 2011. Lagrangian difference maps reveal the spatial distribution of ice shelf thinning, which can primarily be attributed to basal melt. Preliminary results show focused ice shelf thinning within troughs and large basal channels, especially along the western margin of the Dotson ice shelf. These new data

  10. Influence of processing conditions on strut structure and compressive properties of cellular lattice structures fabricated by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Chunlei, E-mail: c.qiu@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Yue, Sheng [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Adkins, Nicholas J.E.; Ward, Mark; Hassanin, Hany [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lee, Peter D., E-mail: peter.lee@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Withers, Philip J., E-mail: p.j.withers@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA (United Kingdom); Attallah, Moataz M., E-mail: m.m.attallah@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2015-03-25

    AlSi10Mg cellular lattice structures have been fabricated by selective laser melting (SLM) using a range of laser scanning speeds and powers. The as-fabricated strut size, morphology and internal porosity were investigated using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray microtomography (micro-CT) and correlated to the compressive properties of the structure. Strut diameter was found to increase monotonically with laser power while the porosity was largest at intermediate powers. Laser scanning speed was found to thicken the struts only at slow rates while the porosity was largest at intermediate speeds. High speed imaging showed the melt pool to be larger at high laser powers. Further the melt pool shape was found to vary cyclically over time, steadily growing before becoming increasingly instable and irregularly shaped before abruptly falling in size due to splashing of molten materials and the process repeating. Upon compressive loading, lattice deformation was homogeneous prior to the peak stress before falling sharply due to the creation of a (one strut wide) shear band at around 45° to the compression axis. The specific yield strength expressed as the yield stress/(yield stress of the aluminium × relative density) is not independent of processing conditions, suggesting that further improvements in properties can be achieved by process optimisation. Lattice struts failed near nodes by a mixture of ductile and brittle fracture.

  11. Rates and Mechanisms of Solidification in Large Magma Bodies: Implications for Melt Extraction in all Tectonic Settings

    Science.gov (United States)

    VanTongeren, J. A.

    2013-12-01

    As is observed in both experiment and theory, in the absence of hydrothermal convection, the majority of magma chamber heat loss occurs via conduction through the roof of the intrusion and into the cold country rock above. The formation of an upper solidification front (or Upper Border Series, UBS), recorded in the rocks both geochemically and texturally, is a natural outcome of the progression of the solidification front from the cold roof to the hot center of the magma chamber. There are, however, a few unique layered mafic intrusions for which little or no UBS exists. In this study, I examine the thermal evolution and crystallization rates of several classic layered intrusions as it is recorded in the extent of the preserved UBS. For those intrusions that have experienced crystallization at the roof, such as the Skaergaard Intrusion, the development of a UBS reduces the temperature gradient at the roof and effectively slows the rate of heat loss from the main magma body. However, for those intrusions that do not have an UBS, such as the Bushveld Complex, the cooling rate is controlled only by the maximum rate of conductive heat loss through the overlying roof rocks, which decreases with time. The implications are two-fold: (1) The relative thickness of the UBS in large intrusions may be the key to quantifying their cooling and solidification rates; and (2) The nature of the magma mush zone near the roof of an intrusion may depend principally on the long-term thermal evolution of the magma body. Particularly at the end stages of crystallization, when the liquids are likely to be highly evolved and high viscosities may inhibit convection, intrusions lacking a well-defined UBS may provide important insights into the mechanics of crystal-liquid separation, melt extraction, and compaction in felsic plutons as well as mafic intrusions. These results are important for long-lived (>500 kyr) or repeatedly replenished magma chambers in all tectonic settings.

  12. Influence of crystal–melt interface shape on self-seeding and single crystalline quality

    Indian Academy of Sciences (India)

    D B Gadkari; P Shashidharan; K B Lal; B M Arora

    2001-10-01

    The growth of Sb-based crystals (InSb, GaSb etc) was undertaken using resistive heater furnace by vertical directional solidification (VDS) technique. Crystal–melt interface shape during the growth was shown to convert from concave to convex along the crystal axis of the ingots. Many antimonide (Sb) crystals of 8 mm to 18 mm diameter were grown by optimized growth parameters. The forced convection and absence of conducting support to ampoule showed improvement in crystal quality of as grown ingots. Crystals showed preferred orientation and self-seeding. Results on interface shape and crystallinity of ingots were found to be in good agreement with the experiments.

  13. Organic Crystal Engineering of Thermosetting Cyanate Ester Monomers: Influence of Structure on Melting Point

    Science.gov (United States)

    2016-05-27

    heating baseline does show a modest non - linearity due to its nearness to the onset of the wide melting peak. Because we elected not to use heating...Guenthner, Sean M. Ramirez , Michael D. Ford, Denisse Soto, Jerry A. Boatz, Kamran B. Ghiassi and Joseph M. Mabry 5d. PROJECT NUMBER 5e. TASK...longer Si-C bonds for C-C bonds in the monomer chemical structure results in the “unlocking” of new degrees of freedom in non -interlocking molecules

  14. Influence of direct bias current on the electromagnetic properties of melt-extracted microwires and their composites

    Science.gov (United States)

    Qin, F. X.; Tang, J.; Popov, V. V.; Liu, J. S.; Peng, H. X.; Brosseau, C.

    2014-01-01

    We study the influence of a direct bias current on the magnetoimpedance (MI) in melt-extracted amorphous CoFeSiB microwires and the effective electromagnetic properties of epoxy composites filled with these microwires. Our analysis reveals two remarkable features of the current dependence of MI in the range of gigahertz frequencies: a redshift of the dielectric resonance frequency and a decrease of the peak resonance of the effective permittivity as the bias current increases. Both effects are intrinsically linked to the influence of the polymer matrix on the magnetic structure and properties of the microwires. A discussion of these results is proposed in terms of two competing effects of the bias current, i.e., the induced additional effective field in the plane normal to the wire axis and the stress relief from Joule heating.

  15. Enhanced dissolution rate and oral bioavailability of Ginkgo biloba extract by preparing solid dispersion via hot-melt extrusion.

    Science.gov (United States)

    Wang, Wenping; Kang, Qian; Liu, Na; Zhang, Qing; Zhang, Yewen; Li, Hui; Zhao, Bochen; Chen, Yanyan; Lan, Yi; Ma, Qiang; Wu, Qing

    2015-04-01

    The aim of this study was to improve the dissolution rate and oral bioavailability of Ginkgo biloba extract (GBE) through the preparation of G. biloba extract solid dispersions (GBE-SD) via hot-melt extrusion (HME). First, we prepared the GBE-SD based on a Kollidon® VA64/Kolliphor® RH40 (85:15) spray dried powder. Then physicochemical properties were investigated by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared spectroscopy (FT-IR). The results indicated that GBE dispersed well in a carrier matrix. Subsequently, we studied the dissolution profile of total flavonoids (TFs) by HPLC-UV and total terpene lactones (TTLs) by HPLC-ELSD. The dissolution percentage of TFs and TTLs was improved within 120min. Finally, we studied the pharmacokinetic characteristics and bioavailability in rats by UPLC-MS/MS. The results showed that the Cmax and AUC0-t of bilobalide (BB), ginkgolide A (GA), ginkgolide B (GB), ginkgolide C (GC), quercetin (QCT), kaempferol (KMF) and isorhamnetin (ISR) in rats were significantly increased after the oral administration of GBE-SD compared with results after the oral administration of GBE. These results suggest that the solid dispersion preparation by HME could serve as a promising formulation approach to enhancing the dissolution rate and oral bioavailability of GBE.

  16. Bottom melting of Arctic Sea Ice in the Nansen Basin due to Atlantic Water influence

    Science.gov (United States)

    Muilwijk, Morven; Smedsrud, Lars H.; Meyer, Amelie

    2016-04-01

    Our global climate is warming, and a shrinking Arctic sea ice cover remains one of the most visible signs of this warming. Sea Ice loss is now visible for all months in all regions of the Arctic. Hydrographic and current observations from a region north of Svalbard collected during the Norwegian Young Sea Ice Cruise (N-ICE2015) are presented here. Comparison with historical data shows that the new observations from January through June fill major gaps in available observations, and help describing important processes linking changes in regional Atlantic Water (AW) heat transport and sea ice. Warm and salty AW originating in the North Atlantic enters the Arctic Ocean through the Fram Strait and is present below the Arctic Sea Ice cover throughout the Arctic. However, the depth of AW varies by region and over time. In the region north of Svalbard, we assume that depth could be governed primarily by local processes, by upstream conditions of the ice cover (Northwards), or by upstream conditions of the AW (Southwards). AW carries heat corresponding to the volume transport of approximately 9 SV through Fram Strait, varying seasonally from 28 TW in winter to 46 TW in summer. Some heat is recirculated, but the net annual heat flux into the Arctic Ocean from AW is estimated to be around 40 TW. The Atlantic Water layer temperature at intermediate depths (150-900m) has increased in recent years. Until recently, maximum temperatures have been found to be 2-3 C in the Nansen Basin. Studies have shown that for example, in the West Spitsbergen Current the upper 50-200m shows an overall AW warming of 1.1 C since 1979. In general we expect efficient melting when AW is close to the surface. Previously the AW entering through Fram Strait has been considered as less important because changes in the sea ice cover have been connected to greater inflow of Pacific Water through Bering Strait and atmospheric forcing. Conversely it is now suggested that AW has direct impact on melting of

  17. InfluenceTracker: Rating the impact of a Twitter account

    OpenAIRE

    Razis, Gerasimos; Anagnostopoulos, Ioannis

    2014-01-01

    Part 2: MHDW Workshop; International audience; This paper describes a methodology for rating the influence of a Twitter account in this famous microblogging service. Then it is evaluated over real accounts, under the belief that influence is not only a matter of quantity (amount of followers), but also a mixture of quality measures that reflect interaction, awareness, and visibility in the social sphere. The authors of this paper have created “InfluenceTracker”, a publicly available website w...

  18. XCT analysis of the influence of melt strategies on defect population in Ti–6Al–4V components manufactured by Selective Electron Beam Melting

    Energy Technology Data Exchange (ETDEWEB)

    Tammas-Williams, S., E-mail: Samuel.tammas-wiliams@manchester.ac.uk [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Zhao, H. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Léonard, F. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); Derguti, F.; Todd, I. [Department of Materials Science and Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Prangnell, P.B. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom)

    2015-04-15

    Selective Electron Beam Melting (SEBM) is a promising powder bed Additive Manufacturing technique for near-net-shape manufacture of high-value titanium components. However without post-manufacture HIPing the fatigue life of SEBM parts is currently dominated by the presence of porosity. In this study, the size, volume fraction, and spatial distribution of the pores in model samples have been characterised in 3D, using X-ray Computed Tomography, and correlated to the process variables. The average volume fraction of the pores (< 0.2%) was measured to be lower than that usually observed in competing processes, such as selective laser melting, but a strong relationship was found with the different beam strategies used to contour, and infill by hatching, a part section. The majority of pores were found to be small spherical gas pores, concentrated in the infill hatched region; this was attributed to the lower energy density and less focused beam used in the infill strategy allowing less opportunity for gas bubbles to escape the melt pool. Overall, increasing the energy density or focus of the beam was found to correlate strongly to a reduction in the level of gas porosity. Rarer irregular shaped pores were mostly located in the contour region and have been attributed to a lack of fusion between powder particles. - Graphical abstract: Display Omitted - Highlights: • Vast majority of defects detected were small spherical gas pores. • Gas bubbles trapped in the powder granules expand and coalesce in the melt pool. • Pores have been shown not to be randomly distributed. • Larger and deeper melt pools give more opportunity for gas to escape. • Minor changes to melt strategy result in significant reductions in pore population.

  19. Influence of electron beam melting manufactured implants on ingrowth and shear strength in an ovine model.

    Science.gov (United States)

    Bertollo, Nicky; Da Assuncao, Ruy; Hancock, Nicholas J; Lau, Abe; Walsh, William R

    2012-09-01

    Arthroplasty has evolved with the application of electron beam melting (EBM) in the manufacture of porous mediums for uncemented fixation. Osseointegration of EBM and plasma-sprayed titanium (Ti PS) implant dowels in adult sheep was assessed in graduated cancellous defects and under line-to-line fit in cortical bone. Shear strength and bony ingrowth (EBM) and ongrowth (Ti PS) were assessed after 4 and 12 weeks. Shear strength of EBM exceeded that for Ti PS at 12 weeks (P = .030). Ongrowth achieved by Ti PS in graduated cancellous defects followed a distinctive pattern that correlated to progressively decreasing radial distances between defect and implant, whereas cancellous ingrowth values at 12 weeks for the EBM were not different. Osteoconductive porous structures manufactured using EBM present a viable alternative to traditional surface treatments. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Influence of Controlled Cooling in Bimodal Scaffold Fabrication Using Polymers with Different Melting Temperatures.

    Science.gov (United States)

    Lara-Padilla, Hernan; Mendoza-Buenrostro, Christian; Cardenas, Diego; Rodriguez-Garcia, Aida; Rodriguez, Ciro A

    2017-06-11

    The combination of different materials and capabilities to manufacture at several scales open new possibilities in scaffold design for bone regeneration. This work is focused on bimodal scaffolds that combine polylactic acid (PLA) melt extruded strands with polycaprolactone (PCL) electrospun fibers. This type of bimodal scaffold offers better mechanical properties, compared to the use of PCL for the extruded strands, and provides potential a means for controlled drug and/or growth factor delivery through the electrospun fibers. The technologies of fused deposition modeling (FDM) and electrospinning were combined to create 3D bimodal constructs. The system uses a controlled cooling system allowing the combination of polymers with different melting temperatures to generate integrated scaffold architecture. The thermoplastic polymers used in the FDM process enhance the mechanical properties of the bimodal scaffold and control the pore structure. Integrated layers of electrospun microfibers induce an increase of the surface area for cell culture purposes, as well as potential in situ controlled drug and/or growth factor delivery. The proposed bimodal scaffolds (PLA extruded strands and PCL electrospun fibers) show appropriate morphology and better mechanical properties when compared to the use of PCL extruded strands. On average, bimodal scaffolds with overall dimensions of 30 × 30 × 2.4 mm³ (strand diameter of 0.5 mm, strand stepover of 2.5 mm, pore size of 2 mm, and layer height of 0.3 mm) showed scaffold stiffness of 23.73 MPa and compression strength of 3.85 MPa. A cytotoxicity assay based human fibroblasts showed viability of the scaffold materials.

  1. Influence of Controlled Cooling in Bimodal Scaffold Fabrication Using Polymers with Different Melting Temperatures

    Directory of Open Access Journals (Sweden)

    Hernan Lara-Padilla

    2017-06-01

    Full Text Available The combination of different materials and capabilities to manufacture at several scales open new possibilities in scaffold design for bone regeneration. This work is focused on bimodal scaffolds that combine polylactic acid (PLA melt extruded strands with polycaprolactone (PCL electrospun fibers. This type of bimodal scaffold offers better mechanical properties, compared to the use of PCL for the extruded strands, and provides potential a means for controlled drug and/or growth factor delivery through the electrospun fibers. The technologies of fused deposition modeling (FDM and electrospinning were combined to create 3D bimodal constructs. The system uses a controlled cooling system allowing the combination of polymers with different melting temperatures to generate integrated scaffold architecture. The thermoplastic polymers used in the FDM process enhance the mechanical properties of the bimodal scaffold and control the pore structure. Integrated layers of electrospun microfibers induce an increase of the surface area for cell culture purposes, as well as potential in situ controlled drug and/or growth factor delivery. The proposed bimodal scaffolds (PLA extruded strands and PCL electrospun fibers show appropriate morphology and better mechanical properties when compared to the use of PCL extruded strands. On average, bimodal scaffolds with overall dimensions of 30 × 30 × 2.4 mm3 (strand diameter of 0.5 mm, strand stepover of 2.5 mm, pore size of 2 mm, and layer height of 0.3 mm showed scaffold stiffness of 23.73 MPa and compression strength of 3.85 MPa. A cytotoxicity assay based human fibroblasts showed viability of the scaffold materials.

  2. Persistent influence of ice sheet melting on high northern latitude climate during the early Last Interglacial

    Directory of Open Access Journals (Sweden)

    A. Govin

    2011-10-01

    Full Text Available Although the Last Interglacial (LIG is often considered as a possible analogue for future climate in high latitudes, its precise climate evolution and associated causes remain uncertain. Here we compile high-resolution marine sediment records from the North Atlantic, Labrador Sea, Norwegian Sea and the Southern Ocean. We document a delay in the establishment of peak interglacial conditions in the North Atlantic, Labrador and Norwegian Seas as compared to the Southern Ocean. In particular, we observe a persistent iceberg melting at high northern latitudes at the beginning of the LIG. It suggests that the input of meltwater has maintained (1 colder and fresher surface-water conditions in the North Atlantic, Labrador and Norwegian Seas and (2 weaker ventilation of North Atlantic deep waters during the early LIG (129–125.5 ka compared to the late LIG. Results from an ocean-atmosphere coupled model with insolation as a sole forcing for three key periods of the LIG show that insolation variations alone lead to warmer North Atlantic surface waters and stronger Atlantic overturning during the early LIG (126 ka than the late LIG (122 ka. Hence insolation variations alone do not explain the delay in peak interglacial conditions observed at high northern latitudes. When freshwater input is interactively computed at 126 ka in response to the high boreal summer insolation, the model simulates colder, fresher North Atlantic surface waters and weaker Atlantic overturning during the early LIG (126 ka compared to the late LIG (122 ka. This result indicates that both insolation variations and ice sheet melting have to be considered to reproduce the LIG climate evolution and supports our hypothesis that optimal thermal and deep ocean circulation conditions at high northern latitudes develop during the late LIG only, when the freshwater supply has already ceased.

  3. Persistent influence of ice sheet melting on high northern latitude climate during the early Last Interglacial

    Directory of Open Access Journals (Sweden)

    A. Govin

    2012-03-01

    Full Text Available Although the Last Interglacial (LIG is often considered as a possible analogue for future climate in high latitudes, its precise climate evolution and associated causes remain uncertain. Here we compile high-resolution marine sediment records from the North Atlantic, Labrador Sea, Norwegian Sea and the Southern Ocean. We document a delay in the establishment of peak interglacial conditions in the North Atlantic, Labrador and Norwegian Seas as compared to the Southern Ocean. In particular, we observe a persistent iceberg melting at high northern latitudes at the beginning of the LIG. It is associated with (1 colder and fresher surface-water conditions in the North Atlantic, Labrador and Norwegian Seas, and (2 a weaker ventilation of North Atlantic deep waters during the early LIG (129–125 ka compared to the late LIG. Results from an ocean-atmosphere coupled model with insolation as a sole forcing for three key periods of the LIG show warmer North Atlantic surface waters and stronger Atlantic overturning during the early LIG (126 ka than the late LIG (122 ka. Hence, insolation variations alone do not explain the delay in peak interglacial conditions observed at high northern latitudes. Additionally, we consider an idealized meltwater scenario at 126 ka where the freshwater input is interactively computed in response to the high boreal summer insolation. The model simulates colder, fresher North Atlantic surface waters and weaker Atlantic overturning during the early LIG (126 ka compared to the late LIG (122 ka. This result suggests that both insolation and ice sheet melting have to be considered to reproduce the climatic pattern that we identify during the early LIG. Our model-data comparison also reveals a number of limitations and reinforces the need for further detailed investigations using coupled climate-ice sheet models and transient simulations.

  4. Efficient determination of crystallisation and melting points at low cooling and heating rates with novel computer controlled equipment

    Energy Technology Data Exchange (ETDEWEB)

    Wachter, Philipp [Institut fuer Physikalische und Theoretische Chemie der Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Schweiger, Hans-Georg [Institut fuer Physikalische und Theoretische Chemie der Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Continental Automotive Systems Division, Sickingenstrasse 29-38, D-10553 Berlin (Germany); Wudy, Franz [Institut fuer Physikalische und Theoretische Chemie der Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany); Gores, Heiner J. [Institut fuer Physikalische und Theoretische Chemie der Universitaet Regensburg, Universitaetsstrasse 31, D-93040 Regensburg (Germany)], E-mail: Heiner.Gores@Chemie.Uni-Regensburg.de

    2008-10-15

    We studied melting and solidification points of 14 pure solvents and two ionic liquids with a recently constructed automatic computer-controlled equipment, which is able to record simultaneously temperature-time functions of up to 30 samples at very low heating and cooling rates down to 1.5 K . h{sup -1}. The effects of viscosity of the studied samples and of carbon fibres as an added crystallisation aid were also investigated. Equilibrium temperatures for the solid-liquid phase transition are in accordance with literature for materials that were often checked, such as acetonitrile, showing the quality of our new equipment, whereas the value of the transition temperature of some other materials differed from published results. It is shown that both the viscosity of the material and carbon fibres as crystallisation aids have an effect on supercooling. The value given for the equilibrium point of the ionic liquid trioctylmethylammonium trifluorocetate T{sub tr} = (285.62 {+-} 0.1) K is new.

  5. Influence of Process Parameters on the Quality of Aluminium Alloy EN AW 7075 Using Selective Laser Melting (SLM)

    Science.gov (United States)

    Kaufmann, N.; Imran, M.; Wischeropp, T. M.; Emmelmann, C.; Siddique, S.; Walther, F.

    Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be manufactured with high accuracy and little post processing. Currently, different steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop the SLM process for the wide used aluminium alloy EN AW 7075. Before process development, the gas-atomized powder material was characterized in terms of statistical distribution: size and shape. A wide range of process parameters were selected to optimize the process in terms of optimum volume density. The investigations resulted in a relative density of over 99%. However, all laser-melted parts exhibit hot cracks which typically appear in aluminium alloy EN AW 7075 during the welding process. Furthermore the influence of processing parameters on the chemical composition of the selected alloy was determined.

  6. CONTROL ALGORITMS OF BOF MELTING WITH CONSIDERING THE INFLUENCE OF UNCONTROLLED DISTURBANCE

    Directory of Open Access Journals (Sweden)

    V. S. Bogushevsky

    2016-01-01

    Full Text Available The article describes influence of uncontrollable disturbances for output parameters of converting smelting. You also find numerical values of impact impurity of scrap, falling mixer slag with cast iron, limestone instead of lime and water from cooled elements on decarbonization, bathtub temperature and slag basicity. Created a control algorithm with the influence of uncontrolled disturbance.

  7. The Influence of Selective Laser Melting Parameters on Density and Mechanical Properties of AlSi10Mg

    Directory of Open Access Journals (Sweden)

    Raus A. A.

    2016-01-01

    Full Text Available Selective Laser Melting (SLM is one of the most effective powder bed technique in the additive Manufacturing (AM which able to fabricate functional metal parts directly from 3D Computer Aided Design (CAD file data. In this paper, the influence of SLM parameters, such as laser power, scanning speed and hatching distance on the density of AlSi10Mg samples are investigated using one factor at a time (OFAT. Furthermore, the optimum results are used to fabricate samples for hardness, tensile strength, and impact toughness test. It is revealed that AlSi10Mg parts fabricated by SLM achieving the best density of 99.13% at the value of 350 watts laser power, 1650 mm/s scanning speed and hatching distance 0.13mm, whereby resulted comparable and even better mechanical properties to those of conventionally HDPC A360F and HDPC A360T6 alloys although without any comprehensive post processing methods.

  8. Surface Observation and Pore Size Analyses of Polypropylene/Low-Melting Point Polyester Filter Materials: Influences of Heat Treatment

    Directory of Open Access Journals (Sweden)

    Lin Jia-Horng

    2016-01-01

    Full Text Available This study proposes making filter materials with polypropylene (PP and low-melting point (LPET fibers. The influences of temperatures and times of heat treatment on the morphology of thermal bonding points and average pore size of the PP/LPET filter materials. The test results indicate that the morphology of thermal bonding points is highly correlated with the average pore size. When the temperature of heat treatment is increased, the fibers are joined first with the thermal bonding points, and then with the large thermal bonding areas, thereby decreasing the average pore size of the PP/LPET filter materials. A heat treatment of 110 °C for 60 seconds can decrease the pore size from 39.6 μm to 12.0 μm.

  9. Influence of electron beam Irradiation on PP/Piassava fiber composite prepared by melt extrusion process

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Michelle G.; Ferreira, Maiara S.; Oliveira, Rene R.; Silva, Valquiria A.; Teixeira, Jaciele G.; Moura, Esperidiana A.B., E-mail: michellegoncalvesgomes@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    In the latest years, the interest for the use of natural fibers in materials composites polymeric has increased significantly due to their environmental and technological advantages. Piassava fibers (Attalea funifera) have been used as reinforcement in the matrix of thermoplastic and thermoset polymers. In the present work (20%, in mass), piassava fibers with particle sizes equal or smaller than 250 μm were incorporated in the polypropylene matrix (PP) no irradiated and polypropylene matrix containing 10 % and 30 % of polypropylene treated by electron-beam radiation at 40 kGy (PP/PPi/Piassava). The composites PP/Piassava and PP/PPi/Piassava were prepared by using a twin screw extruder, followed by injection molding. The composite material samples obtained were treated by electron-beam radiation at 40 kGy, using a 1.5 MeV electron beam accelerator, at room temperature, in presence of air. After irradiation treatment, the irradiated and non-irradiated specimens tests samples were submitted to thermo-mechanical tests, melt flow index (MFI), sol-gel analysis, X-Ray diffraction (XRD) and scanning electron microscopy (SEM). (author)

  10. Immiscible silicate liquids at high pressure: the influence of melt structure on elemental partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Vicenzi, E. [Princeton Materials Laboratory, Princeton, NJ (United States); Green, T.H. [Macquarie Univ., North Ryde, NSW (Australia); Sie, S.H. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience

    1993-12-31

    Micro-PIXE analyses have been applied to study partitioning of trace elements between immiscible silicate melts stabilised at 0.5 and 1.0 GPa over a temperature range of 1160-1240 deg C in the system SiO{sub 2}-FeO-Al{sub 2}0{sub 3}-K{sub 2}0 (+P{sub 2}0{sub 5}). The system was doped with a suite of trace elements of geochemical interest: Rb, Ba, Pb, Sr, La, Ce, Sm, Ho, Y, Lu, Th, U, Zr, Hf, Nb and Ta at approximately 200 ppm level for all elements except for the REE`s, Ba and Ta (600-1200 ppm). Trace element partitioning was found to be a complex function of cation field strength (charge/radius{sup 2}). Although field strength is important in determining the nature and degree of partitioning, the authors emphasised that it is only one component of the underlying mechanism for the way in which elements distribute themselves between two silicate liquids. 8 refs., 2 figs.

  11. Influence of DE-value on the physicochemical properties of maltodextrin for melt extrusion processes.

    Science.gov (United States)

    Castro, Natalia; Durrieu, Vanessa; Raynaud, Christine; Rouilly, Antoine

    2016-06-25

    In this study, five different types of maltodextrins (DE-2, DE-6, DE-12, DE-17 and DE-19) were characterized for the physico-chemical properties. TGA, DVS and SEC analyses were carried out and additionally apparent melt-viscosity (in a micro-extruder) and the glass transition temperature (analyzed by DMA) of maltodextrin/plasticizer mixtures were also measured in order to evaluate both the effect of plasticizer nature and content and the effect of the DE-value. For this, three plasticizing agents were compared: water, d-sorbitol and glycerin. The adsorption isotherms showed that depending on the DE-value and the relative humidity they were exposed to, different behavior could be obtained. For example, for relative humidities below 60% RH maltodextrin DE-2 was the least hygroscopic. And on the contrary for relative humidities above 75% RH maltodextrin DE-2 was the most hygroscopic. The rheology measurements showed that the viscosity decreased with the increase of the DE-value and with the plasticizer content, as expected. On the contrary, no direct correlation could be established between the DE-value and the glass transition temperature. These results demonstrated that to predict maltodextrins behavior and to better adapt the process conditions, combined analyses are mandatory as the DE-value alone is not sufficient. The most compelling evidence was obtained by size exclusion chromatography, which pointed out that maltodextrins had a bimodal molecular weight distribution composed of high and low molecular weight oligo-saccharides. Indeed, maltodextrins are highly polydisperse materials (i.e. polydispersity index ranging from 5 to 12) and that should be the reason why such distinct behaviors were observed in some of the physico-chemical analyses that were preformed.

  12. The Influence of Nitride on the Melting Cu-Al Alloys Conductions

    Directory of Open Access Journals (Sweden)

    Bydałek, A. W.

    2006-01-01

    Full Text Available In some copper alloys can be not exept influence of nitrogen sevant as a refining gas on the character of structure and on other properties cannot be expected. Taking into account high stimina requirements placed aluminium bronzes, except rafination, is necessary the modification of structure. Because in both cases (the refining and modification the nitrogen can have the essential influence on the structure and properties of copper alloys. It was decided to conduct the analysis of phenomenon proceeded during the refining with modification.

  13. PECULIARITIES OF STRUCTURE-FORMATION AT SVS IN MELTED CONDENSED MIXTURES AT INFLUENCE OF CENTRIFUGAL FORCE

    Directory of Open Access Journals (Sweden)

    V. V. Hubovich

    2007-01-01

    Full Text Available The influence of centrifugal force on dynamics of the burning wave spread and the carbide particles distribution in metallic alloy in the process of SVS-casting is considered. It was concluded that centrifugal force can be used for production of materials with gradient of the hardening particles concentration.

  14. Factors Influencing the Success Rate of Cardiopulmonary Resuscitation

    Directory of Open Access Journals (Sweden)

    Aisyah Amanda Hanif

    2015-12-01

    Full Text Available Background: Cardiopulmonary resuscitation (CPR is a series of actions performed on cardiac arrest patients. Not all patients receiving CPR can survive. The outcome of CPR is influenced by several factors. This study was conducted to determine the success rate of CPR and the factors influencing it in Dr. Hasan Sadikin General Hospital in 2013. Methods: This study was conducted by using 168 patient medical records who underwent CPR and met the inclusion criteria in the Resuscitation Room of Dr. Hasan Sadikin General Hospital from January to December 2013. The collected data consisted of age, gender, pre-arrest diagnosis, initial rhythm, response time and clinical outcome of CPR. The results were expressed in frequencies and percentage. The data were analyzed using the chi-square test. Results: The Success rate of CPR was 15.5%. The success rate was higher in patients with cardiac prearrest diagnoses (8.33%, p=0.024. The most common initial rhythm was unshockable rhythms (83.92%, yet patients with shockable heart rhythms had higher success rates (40.74%, p<0.001. All of the surviving patients had response time within the first minute from cardiac arrest. Conclusions: Success rate of CPR in the resuscitation room of Dr. Hasan Sadikin General Hospital during 2013 is still low. The factors influencing the survival rate are the pre-arrest diagnosis and initial heart rhythm.

  15. Influence of gravitational and vibrational convection on the heat- and mass transfer in the melt during crystal growing by Bridgman and floating zone methods

    Science.gov (United States)

    Fedorov, Oleg

    2016-07-01

    Space materials science is one of the priorities of different national and international space programs. The physical processes of heat and mass transfer in microgravity (including effect of g-jitter) is far from complete clarity, especially for important practical technology for producing crystals from the melt. The idea of the impact on crystallizing melt by low frequency vibration includes not only the possibility to suppress unwanted microaccelerations, but also to actively influence the structure of the crystallization front. This approach is one of the most effective ways to influence the quality of materials produced in flight conditions. The subject of this work is the effect of vibrations on the thermal and hydrodynamic processes during crystal growth using Bridgman and floating zone techniques, which have the greatest prospect of practical application in space. In the present approach we consider the gravitational convection, Marangoni convection, as well as the effect of vibration on the melt for some special cases. The results of simulation were compared with some experimental data obtained by the authors using a transparent model substance - succinonitrile (Bridgman method), and silicon (floating zone method). Substances used, process parameters and characteristics of the experimental units correspond the equipment developed for onboard research and serve as a basis for selecting optimum conditions vibration exposure as a factor affecting the solidification pattern. The direction of imposing vibrations coincides with the axis of the crystal, the frequency is presented by the harmonic law, and the force of gravity was varied by changing its absolute value. Mathematical model considered axisymmetric approximation of joint convective-conductive energy transfer in the system crystal - melt. Upon application of low-frequency oscillations of small amplitude along the axis of growing it was found the suppression of the secondary vortex flows near the

  16. Environmental conditions influence tissue regeneration rates in scleractinian corals.

    Science.gov (United States)

    Sabine, Alexis M; Smith, Tyler B; Williams, Dana E; Brandt, Marilyn E

    2015-06-15

    Natural and anthropogenic factors may influence corals' ability to recover from partial mortality. To examine how environmental conditions affect lesion healing, we assessed several water quality parameters and tissue regeneration rates in corals at six reefs around St. Thomas, US Virgin Islands. We hypothesized that sites closer to developed areas would have poor water quality due to proximity to anthropogenic stresses, which would impede tissue regeneration. We found that water flow and turbidity most strongly influenced lesion recovery rates. The most impacted site, with high turbidity and low flow, recovered almost three times slower than the least impacted site, with low turbidity, high flow, and low levels of anthropogenic disturbance. Our results illustrate that in addition to lesion-specific factors known to affect tissue regeneration, environmental conditions can also control corals' healing rates. Resource managers can use this information to protect low-flow, turbid nearshore reefs by minimizing sources of anthropogenic stress.

  17. THE INFLUENCE OF THE ECONOMIC GROWTH ON THE BIRTH RATE

    Directory of Open Access Journals (Sweden)

    SAVU MIHAELA

    2013-02-01

    Full Text Available The changes occurred over time in the population have effects on the economy, especially the reductions in thebirth rate which may lead to disturbances in the population structure. The relationship between the economic growthand the birth rate in Romania is analysed over an 11-year period, in order to see its intensity. The presentation of theevolution of the gross domestic product and of the birth rate is completed by the calculation of the Spearmancoefficient for determining the intensity of the relationship between the two indicators. The decrease of the birth rate isdetermined, to a modest extent, by the economic growth, with a wide range of factors that influence it. In this situation,the establishment and implementation of a birth rate recovery strategy is highly necessary to reduce the imbalancecreated in the population structure.

  18. Crystallization Kinetics and Melting Behavior of PA1010/Ether-based TPU Blends

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shu-ling; ZHAO Yan; SUN Xiao-bo; JIANG Zhen-hua; WU Zhong-wen; WANG Gui-Bin

    2007-01-01

    Polyamide 1010(PA1010)/thermoplastic poly(ether urethane) elastomer(ether-based TPU) blends were prepared via melt extrusion. The crystallization kinetics and melting behavior of PA1010/ether-based TPU blends were systematically investigated using differential scanning calorimetry. The crystallization kinetics results show that the addition of ether-based TPU hinders the crystallization of PA1010, and the hindrance effect increases with the increase of the concentration of ether-based TPU. Both pure PA1010 and PA1010/ether-based TPU blends exhibit double melting peaks in the process of nonisothermal crystallization. The double melting peaks change differently with the variation of cooling rate and blend composition. The cooling rate only influences the lower melting peak; however, the blend composition influences not only the lower melting peak but also the higher melting peak. The reason for the phenomenon must be the interaction between the two compositions.

  19. Influence of additive laser manufacturing parameters on surface using density of partially melted particles

    Science.gov (United States)

    Rosa, Benoit; Brient, Antoine; Samper, Serge; Hascoët, Jean-Yves

    2016-12-01

    Mastering the additive laser manufacturing surface is a real challenge and would allow functional surfaces to be obtained without finishing. Direct Metal Deposition (DMD) surfaces are composed by directional and chaotic textures that are directly linked to the process principles. The aim of this work is to obtain surface topographies by mastering the operating process parameters. Based on experimental investigation, the influence of operating parameters on the surface finish has been modeled. Topography parameters and multi-scale analysis have been used in order to characterize the DMD obtained surfaces. This study also proposes a methodology to characterize DMD chaotic texture through topography filtering and 3D image treatment. In parallel, a new parameter is proposed: density of particles (D p). Finally, this study proposes a regression modeling between process parameters and density of particles parameter.

  20. Influence of basic heart rate and sex on heart rate turbulence in healthy subjects.

    Science.gov (United States)

    Schwab, Jörg O; Eichner, Gerrit; Veit, Gudrun; Schmitt, Heiko; Lewalter, Thorsten; Lüderitz, Berndt

    2004-12-01

    Acceleration and deceleration of the heart rate after the occurrence of a ventricular premature complex is characterized as heart rate turbulence (HRT). Two parameters quantify heart rate turbulence: onset and slope. The physiological properties have not been clarified in a large cohort of persons yet. This study evaluated properties of HRT, and focused on the influence of basic heart rate and sex on HRT. Using a special protocol, 95 persons were studied prospectively. HRT and its physiological properties were determined in 95 persons using Holter ECGs. The authors found 24% with a turbulence onset 0% and 5% with a turbulence slope women and men (745 vs 817 ms, P linear, weighted regression model revealed that an increased heart rate before a ventricular premature complex is associated with a decreased turbulence onset (P men (P = 0.0022). On the contrary, the study detected no influence of the basic heart rate on turbulence slope in women (P = 0.0015 for the comparison between women and men). Basic heart rate and sex show an influence on HRT and should be considered when using HRT for noninvasive risk stratification.

  1. 熔体流动速率对微孔发泡的影响%The effect of microcellular foams from melt flow rate

    Institute of Scientific and Technical Information of China (English)

    高晓晨

    2015-01-01

    This paper discusses the different melt flow rate of microporous polypropylene foam research, using home-made foam masterbatches Foaming agents after the Second Injection Molding Process standards as a "dumbbell" sample of its conventional mechanical properties, density measurement, and the scanning electron microscope to observe the different melt flow rate of microporous polypropylene fired the bubble hole size and distribution of Study of the matrix melt flow rate and porous foam relations.%本文对不同熔体流动速率的聚丙烯进行了微孔发泡的研究,用自制的发泡母粒,发泡助剂经过二次开模工艺注塑成标准“哑铃”样条,对其常规力学性能,密度进行了测试,并在扫描电镜下观察了不同熔体流动速率的聚丙烯微孔发炮的泡孔尺寸及分布情况,研究了基体熔体流动速率与微孔发泡的关系。

  2. Refining Tungsten Purification by Electron Beam Melting Based on the Thermal Equilibrium Calculation and Tungsten Loss Control

    Science.gov (United States)

    Long, Luping; Liu, Wensheng; Ma, Yunzhu; Liu, Ye; Liu, Shuhua

    2015-10-01

    Electron beam melting (EBM) technology has been considered as one of the key steps for preparing high purity tungsten, and reasonable setting of process parameters is the premise. In this paper, the optimum process parameters obtained from thermal equilibrium calculation and evaporation loss control of tungsten are presented. Effective power is closely related to melting temperature, and the required power for maintaining the superheating melt linearly increases with the increase of melt superheat temperature. The evaporation loss behavior of tungsten is significantly influenced by melting rate and melting temperature. Analysis of experiments show that the best results are realized at melting rate of 1.82 g/s, melting temperature of 4200 K, and the corresponding melting power of 130 kW, in which the main impurity elements in tungsten, such as As, Cd, Mg and Sn, present high removal ratio of 90%, 95%, 85.7% and 90%, respectively.

  3. 影响直流融冰工作效率的探讨%Discussion in influences on efficiencies of DC ice melting

    Institute of Scientific and Technical Information of China (English)

    李敬

    2011-01-01

    In the problems of influences on the efficiency of DC ice melting process in the 500kV power lines using the DC ice melting devices in the 500kV Anshun substation, through analyzing the problems, the solution has been found in order to guarantee the ice melting devices fast operation in the emergency situation.%在500kV安顺变使用直流融冰装置对500kV线路进行融冰过程中出现影响融冰工作效率的几个问题,通过问题的分析找出解决的办法,保障融冰装置在紧急的情况下能快速投入运行。

  4. The influence of cooling rate on the microstructure of stainless steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elmer, J.W.

    1988-09-01

    The emergence of high energy density welding, laser surface modification and rapid solidification as commonly used metallurgical processing techniques has greatly increased the range of cooling rates that can be accessed during the solidification of metals and alloys. The microstructures which develop during these rapid cooling conditions may be significantly different from those which develop during low cooling rate conditions as the result of access to new metastable phases with the additional kinetic limitations that accompany rapid solidification. This investigation explores the influence of cooling rate on a series of seven ternary alloys which span the line of two-fold saturation in the Fe-Ni-Cr system. High speed electron beam surface melting was used to resolidify these alloys at scan speeds up to 5 m/s. The resulting cooling rates were estimated from dendrite arm spacing measurements and were confirmed by heat flow modeling to vary from 7 /times/ 10/sup 0/ /degree/C/s to 8 /times/ 10/sup 6/ /degree/C/s. The microstructures that developed from each solidification condition were examined using optical metallography, electron microprobe analysis, scanning electron microscopy and a vibrating sample magnetometer. These results were used to create diagrams to predict the primary mode of solidification, the ferrite content and the complex microstructural morphologies which develop as a function of interface velocity and composition. 158 refs., 90 figs., 45 tabs.

  5. Influence of low-density polyethylene on the thermal characteristics and crystallinity of high melting point macro- and micro-crystalline waxes

    Energy Technology Data Exchange (ETDEWEB)

    Zaky, Magdy T., E-mail: magdytadrous@hotmail.com [Petroleum Refining Division, Egyptian Petroleum Research Institute (EPRI), 1-Ahmed El-Zomor Street, Hai Al-Zehour, Nasr City, P.O. Box 11727, Cairo (Egypt); Mohamed, Nermen H. [Petroleum Refining Division, Egyptian Petroleum Research Institute (EPRI), 1-Ahmed El-Zomor Street, Hai Al-Zehour, Nasr City, P.O. Box 11727, Cairo (Egypt)

    2010-02-20

    The influence of low-density polyethylene on the thermal characteristics and the crystallinity of high melting point macro- and micro-crystalline waxes were investigated. The samples were prepared through melt blending using mechanical stirrer. The thermal characteristics of the blended samples were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crystallinity of the samples was obtained using X-ray diffraction analyzer (XRD). The observations are discussed in terms of possible changes when the polymer is mixed with two types of waxes. The wax-polymer miscibility differed with the type of the wax and the amount of polymer mixed into the wax. Also, the crystallinity and congealing point of the waxes differed with the amount of polymer mixed into the wax. Moreover, the resulting data indicate that, blending of polymer with high melting point micro-crystalline wax elevates its melting point to reach the limits of high melting point ceresin waxes which can be used in different industrial applications.

  6. Experimental Research of the melting Rate of Water Flow Across Sngle Ice Pillar%水流外掠单体冰柱融化速率试验研究

    Institute of Scientific and Technical Information of China (English)

    孟凡康; 于航

    2014-01-01

    建立水流外掠冰柱实验台,分别开展了水流速度(0.02、0.03、0.04、0.05、0.06和0.07m/s)、水流温度(7、10、13、16和19℃)、冰柱直径(60、70、80和105mm)及冰柱初始温度(-12、-8和-5℃)对于冰柱融化速率的影响研究。通过对融化时间的统计和分析,获得以下结论:水流温度对于融化时间的影响呈幂函数规律;水流速度和冰柱直径对于融化时间的影响呈线性规律;冰柱初始温度对于融化时间影响较小。%The experiment table of water flow across ice pillar was established in this research which mainly analysis how the water velocity (0.02 m/s,0.03 m/s,0.04 m/s,0.05 m/s,0.06 m/s and 0.07m/s),diameter of the ice pillar (60mm、70mm、80mm和105mm),the temperature of water flow(7℃、10℃、13℃、16℃和19℃) and initial temperature of the ice pillar (-12℃、-8℃和-5℃) influenced on the ice pillar melting rate.By analyzing the statistic of melting times,some conclusion could be got as follows:The effects of water temperature on melting time are representing as power function.The effect of water ve-locity and diameter of the ice pillar on melting time are representing as linear.And the influence of initial temperature of ice pillar on melting time has a minimal effect.

  7. Influence of CO2 on melting of model granulite facies assemblages - A model for the genesis of charnockites

    Science.gov (United States)

    Wendlandt, R. F.

    1981-01-01

    A model is described for the melting of a simple granulite assemblage, in the presence of CO2-rich fluid phases, which can occur between 750 and 1000 C at crustal pressures and is therefore within the range estimated for such regional metamorphism as that of the Adirondacks. For melting which occurs at about 750 C in the presence of both H2O and CO2, pressures corresponding to the deep crust are required to generate a melt enriched in pyroxene and feldspar components, while melting the precense of pure CO2 at about 1000 C generates analogous melt compositions at lower pressures. These experimental reactions are in keeping with observations constraining charnockite occurrences: (1) pressure and temperature constraints; (2) mineralogical constraints; and (3) constraints on the compositions of volatiles associated with peak conditions of charnockite formation.

  8. Influence of the permeability of networked primary Si on the ejection of hypereutectic Al-Si melts by centrifugation

    Science.gov (United States)

    Youn, Ji Won; Jeon, Je-Beom; Park, Jin Man; Seo, Seok Yong; Lim, Jeon Taik; Kim, Suk Jun; Kim, Ki Young

    2017-02-01

    The separation of high purity Si for solar cells from Al-Si alloy melt in the mushy zone was investigated using an advanced centrifugal technique. The efficiency of separating Si, based on the weight ratio of separated Si to Si in alloy melt, was maximized by optimizing the permeability of a porous structure of Si (Si foam.) For the optimization of the permeability, two fundamental microstructure variables, size and the solid fraction of primary Si platelets, were controlled by adjusting the Si content in the melts and the rotation start temperature, respectively. The best separation efficiency (48.3% with 3N purity) was achieved when Si content in melt was 24% and the solid fraction was 8.7%. The melt with 23% Si led to a higher separation efficiency (69.8%) for a solid fraction of 10.4%, but Al sandwiched between the Si platelets resulted in a decrease in the purity to 2N.

  9. Arctic melt ponds and energy balance in the climate system

    Science.gov (United States)

    Sudakov, Ivan

    2017-02-01

    Elements of Earth's cryosphere, such as the summer Arctic sea ice pack, are melting at precipitous rates that have far outpaced the projections of large scale climate models. Understanding key processes, such as the evolution of melt ponds that form atop Arctic sea ice and control its optical properties, is crucial to improving climate projections. These types of critical phenomena in the cryosphere are of increasing interest as the climate system warms, and are crucial for predicting its stability. In this paper, we consider how geometrical properties of melt ponds can influence ice-albedo feedback and how it can influence the equilibria in the energy balance of the planet.

  10. The influence of cell morphology on the compressive fatigue behavior of Ti-6Al-4V meshes fabricated by electron beam melting.

    Science.gov (United States)

    Zhao, S; Li, S J; Hou, W T; Hao, Y L; Yang, R; Misra, R D K

    2016-06-01

    Additive manufacturing technique is a promising approach for fabricating cellular bone substitutes such as trabecular and cortical bones because of the ability to adjust process parameters to fabricate different shapes and inner structures. Considering the long term safe application in human body, the metallic cellular implants are expected to exhibit superior fatigue property. The objective of the study was to study the influence of cell shape on the compressive fatigue behavior of Ti-6Al-4V mesh arrays fabricated by electron beam melting. The results indicated that the underlying fatigue mechanism for the three kinds of meshes (cubic, G7 and rhombic dodecahedron) is the interaction of cyclic ratcheting and fatigue crack growth on the struts, which is closely related to cumulative effect of buckling and bending deformation of the strut. By increasing the buckling deformation on the struts through cell shape design, the cyclic ratcheting rate of the meshes during cyclic deformation was decreased and accordingly, the compressive fatigue strength was increased. With increasing bending deformation of struts, fatigue crack growth in struts contributed more to the fatigue damage of meshes. Rough surface and pores contained in the struts significantly deteriorated the compressive fatigue strength of the struts. By optimizing the buckling and bending deformation through cell shape design, Ti-6Al-4V alloy cellular solids with high fatigue strength and low modulus can be fabricated by the EBM technique. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Heart rate and respiratory rate influence on heart rate variability repeatability: effects of the correction for the prevailing heart rate

    Directory of Open Access Journals (Sweden)

    Jakub Sławomir Gąsior

    2016-08-01

    Full Text Available Background: Since heart rate variability (HRV is associated with average heart rate (HR and respiratory rate (RespRate, alterations in these parameters may impose changes in HRV. Hence the repeatability of HRV measurements may be affected by differences in HR and RespRate. The study aimed to evaluate HRV repeatability and its association with changes in HR and RespRate.Methods: Forty healthy volunteers underwent two ECG examinations seven days apart. Standard HRV indices were calculated from 5-min ECG recordings. The ECG-derived respiration signal was estimated to assess RespRate. To investigate HR impact on HRV, HRV parameters were corrected for prevailing HR. Results: Differences in HRV parameters between the measurements were associated with the changes in HR and RespRate. However, in multiple regression analysis only HR alteration proved to be independent determinant of the HRV differences – every change in HR by 1 bpm changed HRV values by 16.5% on average. After overall removal of HR impact on HRV, coefficients of variation of the HRV parameters significantly dropped on average by 26.8% (p < 0.001, i.e. by the same extent HRV reproducibility improved. Additionally, the HRV correction for HR decreased association between RespRate and HRV. Conclusions: In stable conditions, HR but not RespRate is the most powerful factor determining HRV reproducibility and even a minimal change of HR may considerably alter HRV. However, the removal of HR impact may significantly improve HRV repeatability. The association between HRV and RespRate seems to be, at least in part, HR dependent.

  12. Heart Rate and Respiratory Rate Influence on Heart Rate Variability Repeatability: Effects of the Correction for the Prevailing Heart Rate

    Science.gov (United States)

    Gąsior, Jakub S.; Sacha, Jerzy; Jeleń, Piotr J.; Zieliński, Jakub; Przybylski, Jacek

    2016-01-01

    Background: Since heart rate variability (HRV) is associated with average heart rate (HR) and respiratory rate (RespRate), alterations in these parameters may impose changes in HRV. Hence the repeatability of HRV measurements may be affected by differences in HR and RespRate. The study aimed to evaluate HRV repeatability and its association with changes in HR and RespRate. Methods: Forty healthy volunteers underwent two ECG examinations 7 days apart. Standard HRV indices were calculated from 5-min ECG recordings. The ECG-derived respiration signal was estimated to assess RespRate. To investigate HR impact on HRV, HRV parameters were corrected for prevailing HR. Results: Differences in HRV parameters between the measurements were associated with the changes in HR and RespRate. However, in multiple regression analysis only HR alteration proved to be independent determinant of the HRV differences—every change in HR by 1 bpm changed HRV values by 16.5% on average. After overall removal of HR impact on HRV, coefficients of variation of the HRV parameters significantly dropped on average by 26.8% (p < 0.001), i.e., by the same extent HRV reproducibility improved. Additionally, the HRV correction for HR decreased association between RespRate and HRV. Conclusions: In stable conditions, HR but not RespRate is the most powerful factor determining HRV reproducibility and even a minimal change of HR may considerably alter HRV. However, the removal of HR impact may significantly improve HRV repeatability. The association between HRV and RespRate seems to be, at least in part, HR dependent. PMID:27588006

  13. The Influence of Constitutional Supercooling on the Distribution of Te-particles in Melt-Grown CZT

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Alvine, Kyle J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bliss, Mary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stave, Jean A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-03

    A section of a vertical gradient freeze Cd0.9Zn0.1Te boule approximately 2100-mm3 with a planar area of 300-mm2 was prepared and examined using transmitted IR microscopy at various magnifications to determine the three-dimensional spatial and size distributions of Te-particles over large longitudinal and radial length scales. Te-particle density distributions were determined as a function of longitudinal and radial positions in these strips and exhibited a multi-modal lognormal size density distribution that indicated a slight preference for increasing size with longitudinal growth time, while showing a pronounced cellular network structure. Higher magnification images revealed a typical Rayleigh-instability pearl string morphology with large and small satellite droplets. This study includes solidification experiments in small crucibles of 30:70 mixtures of Cd:Te performed over a wide range of cooling rates that clearly demonstrated a growth instability with Te-particle capture that is suggested to be responsible for one of the peaks in the size distribution using size discrimination visualization. The results are discussed with regard to a manifold Te-particle genesis history as Te-particle direct capture from melt-solid growth instabilities due to constitutional supercooling and as Te-particle formation from the breakup of Te-ribbons via a Rayleigh-Plateau instability.

  14. 熔体层厚对聚合物共挤出胀大的影响%Influence analysis of melt thickness on die swell in polymer co-extrusion molding

    Institute of Scientific and Technical Information of China (English)

    宋卫生

    2016-01-01

    基于流变学理论和Phan-Thien-Tanne本构方程,建立了三维等温黏弹共挤成型流动过程的数值模型。运用有限元方法对数值模型进行了模拟计算,研究了熔体层厚对共挤成型的影响,分析了熔体层厚对挤出胀大率、偏转变形及界面形貌的影响。结果表明:熔体层厚对挤出胀大率和界面形貌的影响较大,随着熔体层厚的增加,挤出胀大率减小;随着共挤出熔体层厚差值的增大,界面形状趋于不稳定;熔体离开口模后产生低黏度熔体向高黏度熔体一侧偏转变形,但变形程度受熔体层厚的影响不大。%Based on the rheology theory and Phan-Thien-Tanne (PTT) constitutive equation, the three-dimensional model of isothermal viscoelastic modeling through co-extrusion channel is established for numerical simulation which is carried out by the finite element method. The effect of melt thickness on co-extrusion processes is studied as well as that on die swell, deformation and interface profile. The results show that the melt thickness exerts more impact on die swell and interface profile. The die swell rate decreases with the increasing of melt thickness and the interface profile tends to be instable with the difference of the co-extrusion melts thickness enhancing. The melt deformation happens from the lower viscosity melt to the higher viscosity part after leaving the die, but the melt thickness had little influence on deformation degree.

  15. Influence of surface melting effects and availability of reagent ions on LDI-MS efficiency after UV laser irradiation of Pd nanostructures.

    Science.gov (United States)

    Silina, Yuliya E; Koch, Marcus; Volmer, Dietrich A

    2015-03-01

    In this study, the influence of surface morphology, reagent ions and surface restructuring effects on atmospheric pressure laser desorption/ionization (LDI) for small molecules after laser irradiation of palladium self-assembled nanoparticular (Pd-NP) structures has been systematically studied. The dominant role of surface morphology during the LDI process, which was previously shown for silicon-based substrates, has not been investigated for metal-based substrates before. In our experiments, we demonstrated that both the presence of reagent ions and surface reorganization effects--in particular, melting--during laser irradiation was required for LDI activity of the substrate. The synthesized Pd nanostructures with diameters ranging from 60 to 180 nm started to melt at similar temperatures, viz. 890-898 K. These materials exhibited different LDI efficiencies, however, with Pd-NP materials being the most effective surface in our experiments. Pd nanostructures of diameters >400-800 nm started to melt at higher temperatures, >1000 K, making such targets more resistant to laser irradiation, with subsequent loss of LDI activity. Our data demonstrated that both melting of the surface structures and the presence of reagent ions were essential for efficient LDI of the investigated low molecular weight compounds. This dependence of LDI on melting points was exploited further to improve the performance of Pd-NP-based sampling targets. For example, adding sodium hypophosphite as reducing agent to Pd electrolyte solutions during synthesis lowered the melting points of the Pd-NP materials and subsequently gave reduced laser fluence requirements for LDI.

  16. High interest rate policy in Turkey and factors influencing interest rate spreads

    Directory of Open Access Journals (Sweden)

    Funda Yurdakul

    2009-01-01

    Full Text Available The main purpose of this paper is to examine what factors explain the difference between effective interest rates of Turkey and USA. The paper considers seven variables explaining interest rate spread such as general prices, Gross Domestic Product (GDP, exchange rate, credibility index, level of international reserves, foreign trade deficit, and budget deficit. Four distinct periods were selected to explore the influences of the above mentioned variables on on interest rate spreads in these different time periods. The period covering 1994.1-2006:12 was splitted into three sub-periods: the sub-period covering 1994:1-1998:12, crisis period covering 1999:1-2001:.12, and post-crisis period covering 2002:1-2006.12. Employing the data for Turkey and applying Engle and Granger two-step procedure, this paper concludes that the only variable reducing interest rate spreads in all periods is GDP. The other variables generally increase the interest rate spreads.Engle and Granger estimation procedure, unit-root test, interest rate spreads, interest rate.

  17. High interest rate policy in Turkey and factors influencing interest rate spreads

    Directory of Open Access Journals (Sweden)

    Funda Yurdakul

    2009-01-01

    Full Text Available The main purpose of this paper is to examine what factors explain the difference between effective interest rates of Turkey and USA. The paper considers seven variables explaining interest rate spread such as general prices, Gross Domestic Product (GDP, exchange rate, credibility index, level of international reserves, foreign trade deficit, and budget deficit. Four distinct periods were selected to explore the influences of the above mentioned variables on on interest rate spreads in these different time periods. The period covering 1994.1-2006:12 was splitted into three sub-periods: the sub-period covering 1994:1-1998:12, crisis period covering 1999:1-2001:.12, and post-crisis period covering 2002:1-2006.12.                            Employing the data for Turkey and applying Engle and Granger two-step procedure, this paper concludes that the only variable reducing interest rate spreads in all periods is GDP. The other variables generally increase the interest rate spreads.Engle and Granger estimation procedure, unit-root test, interest rate spreads, interest rate.    

  18. Effect of binders on the release rates of direct molded verapamil tablets using twin-screw extruder in melt granulation.

    Science.gov (United States)

    Tan, David Cheng Thiam; Chin, William Wei Lim; Tan, En Hui; Hong, Shiqi; Gu, Wei; Gokhale, Rajeev

    2014-03-10

    Conventional manufacturing of pharmaceutical tablets often involves single processes such as blending, granulation, milling and direct compression. A process that minimizes and incorporates all these in a single continuous step is desirable. The concept of omitting milling step followed by direct-molding of tablets utilizing a twin-screw extruder in a melt granulation process using thermoplastic binders was explored. The objective of this study was to investigate the effect of combining hydrophilic binder (HPMC K4M, PEO 1M), and hydrophobic binder (Compritol® ATO 888, Precirol® ATO 5) on the release profiles of direct-molded tablets and direct-compressed tablets from milled extrudates using a quality-by-design approach. It was identified that hydrophilic binder type and process significantly affects (p=0.005) the release profiles of verapamil. Moreover, two-way interaction analysis demonstrated that the combination of process with type of hydrophilic polymer (p=0.028) and the type of hydrophilic polymer with polymer ratio (p=0.033) significantly affected the release profiles. The formulation release kinetics correlated to Higuchi release model and the mechanism correlated to a non-Fickian release mechanism. The results of the present study indicated that direct-molded tablets with different release profiles can be manufactured without milling process and through a continuous melt granulation using twin-screw extruder with appropriate thermoplastic binder ratio.

  19. The Influence of Greenland melt water on the temporal and spatial response of the Holocene Thermal Maximum in the Nordic Seas: a modelling study

    Science.gov (United States)

    Blaschek, M.; Renssen, H.

    2012-04-01

    In the early-to-mid Holocene a period of relatively warm climate, known as the Holocene thermal maximum (HTM, 11-5 kyr BP), has been associated with the orbitally-forced northern hemisphere summer insolation maximum at approximately 10 kyr BP. Although the HTM is orbitally forced, the spatial and temporal response of its climate signature is diverse. At 9 kyr BP remnants of glacial ice sheets, most importantly the Laurentide Ice Sheet (LIS), modified the climate of the North Atlantic region by freshening the ocean surface through melt water discharge, and by altering the surface albedo and topography. A previous climate modelling study (Renssen et al. 2009) has shown that the LIS delayed the HTM in the Nordic Seas by up to 3000 years. We extend this approach by introducing another source of melt water in the early Holocene, the Greenland Ice Sheet (GIS). The GIS was likely up to 25% larger (at 9 kyr BP) in volume than at present-day (Vinther et al. 2009, Peltier, 2004) and is therefore potentially an important regional contributor to climate change in the Nordic Seas. We present here simulations performed with the LOVECLIM1.2 global ocean-atmosphere-vegetation model. These simulations seek to highlight the spatial and temporal impact of GIS melting on the early Holocene climate, in terms of sea surface temperature (SST). Several sensitivity experiments with fixed 9 kyr BP forcings were performed for different Greenland melt water fluxes to test model and climate sensitivity. These melt water fluxes range from 0 to 52 mSv. The sensitivity experiments show that GIS melting considerably influences sea surface conditions around the southern part of Greenland, and that 13 to 26 mSv of GIS melting, in a combination with the LIS background melting, agrees better in that region with proxy-based SST reconstructions. In a further step, transient simulations exhibit the long term (9 to 0 kyr BP) impact of GIS melting on the development of the Holocene climate. Transient

  20. The Influence of the Student Mobility Rate on the Graduation Rate in the State of New Jersey

    Science.gov (United States)

    Ross, Lavetta S.

    2016-01-01

    This study examined the influence of the student mobility rate on the high school graduation rate of schools in the state of New Jersey. Variables found to have an influence on the graduation rate in the extant literature were evaluated and reported. The analysis included multiple and hierarchical regression models for school variables (i.e.,…

  1. Modelling the influence of the gas to melt ratio on the fraction solid of the surface in spray formed billets

    DEFF Research Database (Denmark)

    Hattel, Jesper Henri; Pryds, Nini

    2006-01-01

    In this paper, the relationship between the Gas to Melt Ratio (GMR) and the solid fraction of an evolving billet surface is investigated numerically. The basis for the analysis is a recently developed integrated procedure for modelling the entire spray forming process. This model includes...... is the summation of “local” droplet size distributions along the r-axis of the spray cone. The criterion for a successful process has been a predefined process window characterised by a desired solid fraction range at a certain distance from the atomizer. Inside this process window, the gas and melt flows have...

  2. Calcium interacts with temperature to influence Daphnia movement rates

    Science.gov (United States)

    Roszell, Jordan; Heyland, Andreas; Fryxell, John M.

    2016-01-01

    Predicting the ecological responses to climate change is particularly challenging, because organisms might be affected simultaneously by the synergistic effects of multiple environmental stressors. Global warming is often accompanied by declining calcium concentration in many freshwater ecosystems. Although there is growing evidence that these changes in water chemistry and thermal conditions can influence ecosystem dynamics, little information is currently available about how these synergistic environmental stressors could influence the behaviour of aquatic organisms. Here, we tested whether the combined effects of calcium and temperature affect movement parameters (average speed, mean turning frequency and mean-squared displacement) of the planktonic Daphnia magna, using a full factorial design and exposing Daphnia individuals to a range of realistic levels of temperature and calcium concentration. We found that movement increased with both temperature and calcium concentration, but temperature effects became considerably weaker when individuals were exposed to calcium levels close to survival limits documented for several Daphnia species, signalling a strong interaction effect. These results support the notion that changes in water chemistry might have as strong an effect as projected changes in temperature on movement rates of Daphnia, suggesting that even sublethal levels of calcium decline could have a considerable impact on the dynamics of freshwater ecosystems. PMID:28083097

  3. Melting throughout time and energy consumption for TiAl alloys during ISM process

    Institute of Scientific and Technical Information of China (English)

    SU Yan-qing; LIU Gui-zhong; GUO Jing-jie; JIA Jun; FU Heng-zhi

    2005-01-01

    Based on the program developed to simulate the temperature field for ISM(Induction Skull Melting)process,the effects of power increasing rate and charge mass on the melting throughout time and the energy consumption for TiAl alloys were studied. The results show that the melting throughout time decreases exponentially with the increasing of the power increasing rate and it linearly increases with the increasing of the charge mass.There is a critical power increasing rate for different charge masses.At this critical power increasing rate,the charge can be molten when the melting power just reaches 300 kW.There exists an optimal power increasing rate,I.e.1.3 kW/s.At the optimal power increasing rate,the energy consumption for melting the charge is the minimum.The charge mass has noticeable influence on the energy consumed by unit mass and the ratio of effective energy.

  4. The influence of oxide on the electrochemical processes in K2NbF7-NaCl-KCl melts

    DEFF Research Database (Denmark)

    Lantelme, F.; Berghoute, Y.; Barner, Jens H. Von;

    1995-01-01

    Transient electrochemical techniques showed that in NaCl-KCl melts the reduction of K2NbF7 occurs through atwo-step reaction Nb(V) --> Nb(IV) --> Nb. When oxide ions were introduced, cyclic voltammetry indicated that the wavescorresponding to reduction of the complex NbF72- progressively...

  5. Spray forming: A numerical investigation of the influence of the gas to melt ratio on the billet surface temperature

    DEFF Research Database (Denmark)

    Pryds, Nini; Hattel, Jesper

    2005-01-01

    The relationship between the Gas to Melt Ratio (GMR) and the surface temperature of an evolving billet surface in spray forming is investigated numerically. The basis for the analysis is an integrated approach for modelling the entire spray forming process. This model includes the droplet atomisa...

  6. Study of melt flow dynamics and influence on quality for CO{sub 2} laser fusion cutting

    Energy Technology Data Exchange (ETDEWEB)

    Riveiro, A; Quintero, F; Lusquinos, F; Comesana, R; Pou, J [Applied Physics Department, University of Vigo, ETSII, Lagoas-Marcosende, 9, 36310 Vigo (Spain)

    2011-04-06

    The understanding of melt flow dynamics during fusion laser cutting is still a topic of great importance because this determines the quality characteristics of the processed workpiece. Despite the complexity of the experimental study of the physical processes involved in this technique, fusion laser cutting can be visualized during the processing of glass because this material absorbs the laser radiation provided by a CO{sub 2} laser but shows transparency to visible radiation. Then, we present in this work the results of the study of the melt flow dynamics during laser cutting of glass. Under different experimental conditions, the dynamics of the cutting front and its complete geometry (front wall inclination), and the evolution of the melt along the cut edge were analysed using a high-speed video camera to study the process. A phenomenon concerning the plasma plume formed during the process was observed, which has not been previously reported in the literature. This can displace the normal shock wave (MSD) commonly formed in the inlet kerf and can affect the assist gas flow into the kerf. On the other hand, the analysis of the recorded images allowed the determination of not only the amount of molten material along the cut edge but also the direction and velocity of the melt. Relevant processing parameters affecting the flow of molten material were assessed. These results were used as a basis to explain the different processes involved in the generation of dross, a typical imperfection appearing in laser cutting.

  7. Influence of Substrates on the Electrochemical Deposition and Dissolution of Aluminum in NaAlCl4 Melts

    DEFF Research Database (Denmark)

    Li, Qingfeng; Hjuler, Hans Aage; Berg, Rolf W.

    1991-01-01

    The deposition and dissolution of aluminum in NaAlCl4 melts saturated with NaCl have been investigated by voltammetryand potentiometry for different electrode materials at 175°C. The tungsten and glassy carbon electrodes are shownto be electrochemically inert in the melts, whereas copper is elect......The deposition and dissolution of aluminum in NaAlCl4 melts saturated with NaCl have been investigated by voltammetryand potentiometry for different electrode materials at 175°C. The tungsten and glassy carbon electrodes are shownto be electrochemically inert in the melts, whereas copper...... and the coulombic charges used for glassy carbon electrodes, mainly because of poor adhesion of the deposits tothe substrate. The reversibility is noticeably affected by the magnitude of deposition current density for the tungsten electrodes,while it remains high on the nickel electrode under all conditions...... investigated. Nickel and, to some extent,tungsten electrodes proved to be appropriate as working anodes in the Al/NaCl-AlCl3/Ni battery system....

  8. Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability.

    Science.gov (United States)

    May, Linda E; Glaros, Alan; Yeh, Hung-Wen; Clapp, James F; Gustafson, Kathleen M

    2010-04-01

    Previous studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development. This study tested the hypothesis that regular maternal exercise throughout gestation influences fetal cardiac autonomic control of HR and heart rate variability (HRV) when compared to fetuses of non-exercising women. Magnetocardiograms (MCGs) were recorded using a dedicated fetal biomagnetometer at 28, 32 and 36 weeks gestational age (GA) from 26 regularly exercising (>30 min of aerobic exercise, 3x per week) and 35 healthy, non-exercising pregnant women. Fetal MCG was isolated and normal R-peaks were marked to derive fetal HR and HRV in the time and frequency domains. We applied a mixed-effects model to investigate the effects of exercise, GA and fetal activity state. At 36 weeks GA, during the active fetal state, fetal HR was significantly lower in the exercise group (p=exercise group during the active fetal state at 36 weeks GA for both time and frequency domain measures. These results indicate that regular maternal exercise throughout gestation results in significantly lower fetal HR and increased HRV. 2010 Elsevier Ltd. All rights reserved.

  9. Factors influencing crime rates: an econometric analysis approach

    Science.gov (United States)

    Bothos, John M. A.; Thomopoulos, Stelios C. A.

    2016-05-01

    The scope of the present study is to research the dynamics that determine the commission of crimes in the US society. Our study is part of a model we are developing to understand urban crime dynamics and to enhance citizens' "perception of security" in large urban environments. The main targets of our research are to highlight dependence of crime rates on certain social and economic factors and basic elements of state anticrime policies. In conducting our research, we use as guides previous relevant studies on crime dependence, that have been performed with similar quantitative analyses in mind, regarding the dependence of crime on certain social and economic factors using statistics and econometric modelling. Our first approach consists of conceptual state space dynamic cross-sectional econometric models that incorporate a feedback loop that describes crime as a feedback process. In order to define dynamically the model variables, we use statistical analysis on crime records and on records about social and economic conditions and policing characteristics (like police force and policing results - crime arrests), to determine their influence as independent variables on crime, as the dependent variable of our model. The econometric models we apply in this first approach are an exponential log linear model and a logit model. In a second approach, we try to study the evolvement of violent crime through time in the US, independently as an autonomous social phenomenon, using autoregressive and moving average time-series econometric models. Our findings show that there are certain social and economic characteristics that affect the formation of crime rates in the US, either positively or negatively. Furthermore, the results of our time-series econometric modelling show that violent crime, viewed solely and independently as a social phenomenon, correlates with previous years crime rates and depends on the social and economic environment's conditions during previous years.

  10. Influence of Mechanical Stirring on the Crucible Dissolution Rate and Impurities Distribution in Directional Solidification of Multicrystalline Silicon

    Directory of Open Access Journals (Sweden)

    Popescu Alexandra

    2015-12-01

    Full Text Available In this study, time dependent three-dimensional numerical simulations were carried out using the STHAMAS3D software in order to understand the effects of forced convection induced by mechanical stirring of the melt, on the crucible dissolution rate and on the impurities distribution in multicrystalline silicon (mc-Si melt for different values of the diffusion coefficient.

  11. Influence of User Ratings, Expert Ratings and Purposes of Information Use on the Credibility Judgments of College Students

    Science.gov (United States)

    Lim, Sook; Steffel, Nick

    2015-01-01

    Introduction: This study examined whether user ratings, expert ratings and the purpose of the use of a book on a user-generated site influenced the credibility of the book. It also examined whether the effects of user ratings and expert ratings on credibility judgments of the book varied according to the purpose of information use. In addition,…

  12. The influence of a grain boundary on the thermal transport properties of bulk, melt-processed Y-Ba-Cu-O

    Science.gov (United States)

    Marchal, C.; Fagnard, J. F.; Shi, Y. H.; Cardwell, D. A.; Mucha, J.; Misiorek, H.; Cloots, R.; Vertruyen, B.; Vanderbemden, P.

    2013-01-01

    We report the dependence of thermal conductivity, thermoelectric power and electrical resistivity on temperature for a bulk, large grain melt-processed Y-Ba-Cu-O (YBCO) high temperature superconductor (HTS) containing two grains separated by a well-defined grain boundary. Transport measurements at temperatures between 10 and 300 K were carried out both within one single grain (intra-granular properties) and across the grain boundary (inter-granular properties). The influence of an applied external magnetic field of up to 8 T on the measured sample properties was also investigated. The presence of the grain boundary is found to affect strongly the electrical resistivity of the melt-processed bulk sample, but has almost no effect on its thermoelectric power and thermal conductivity, within experimental error. The results of this study provide direct evidence that the heat flow in multi-granular melt-processed YBCO bulk samples should be virtually unaffected by the presence of grain boundaries in the material.

  13. Influence of Contact Angle, Growth Angle and Melt Surface Tension on Detached Solidification of InSb

    Science.gov (United States)

    Wang, Yazhen; Regel, Liya L.; Wilcox, William R.

    2000-01-01

    We extended the previous analysis of detached solidification of InSb based on the moving meniscus model. We found that for steady detached solidification to occur in a sealed ampoule in zero gravity, it is necessary for the growth angle to exceed a critical value, the contact angle for the melt on the ampoule wall to exceed a critical value, and the melt-gas surface tension to be below a critical value. These critical values would depend on the material properties and the growth parameters. For the conditions examined here, the sum of the growth angle and the contact angle must exceed approximately 130, which is significantly less than required if both ends of the ampoule are open.

  14. Influence of clusters in melt on the subsequent glass-formation and crystallization of Fe-Si-B metallic glasses

    Institute of Scientific and Technical Information of China (English)

    Shaoxiong Zhou; Bangshao Dong; Rui Xiang; Guangqiang Zhang; Jingyu Qin; Xiufang Bian

    2015-01-01

    The liquid structure of seven representative Fe–Si–B alloys has been investigated by ab initio molecular dynamics simulation focusing on the role of clusters in terms of glass-forming ability (GFA) and crystallization. It is demonstrated that the type of primary phase precipitated from amorphous state under heat treatment is determined by the relative fraction and role of various clusters in melt. The alloy melt shows higher stability and resultantly larger GFA when there is no dominant cluster or several clusters coexist, which explains the different GFAs and crystallization processes at various ratios of Si and B in the Fe–Si–B system. The close correlation among clusters, crystalline phase and GFA is also studied.

  15. Influence of clusters in melt on the subsequent glass-formation and crystallization of Fe–Si–B metallic glasses

    Directory of Open Access Journals (Sweden)

    Shaoxiong Zhou

    2015-04-01

    Full Text Available The liquid structure of seven representative Fe–Si–B alloys has been investigated by ab initio molecular dynamics simulation focusing on the role of clusters in terms of glass-forming ability (GFA and crystallization. It is demonstrated that the type of primary phase precipitated from amorphous state under heat treatment is determined by the relative fraction and role of various clusters in melt. The alloy melt shows higher stability and resultantly larger GFA when there is no dominant cluster or several clusters coexist, which explains the different GFAs and crystallization processes at various ratios of Si and B in the Fe–Si–B system. The close correlation among clusters, crystalline phase and GFA is also studied.

  16. Migration of additive molecules in a polymer filament obtained by melt spinning: Influence of the fiber processing steps

    Energy Technology Data Exchange (ETDEWEB)

    Gesta, E. [Ingénierie des Matériaux Polymères - UMR CNRS 5223, Université de Lyon - Université Lyon 1, Bâtiment POLYTECH Lyon - 15 boulevard Latarjet, 69622, Villeurbanne (France); Intelligent Insect Control, 118 Chemin des Alouettes, Castelnau-le-Lez, 34170 (France); Skovmand, O., E-mail: osk@insectcontrol.net [Intelligent Insect Control, 118 Chemin des Alouettes, Castelnau-le-Lez, 34170 (France); Espuche, E., E-mail: eliane.espuche@univ-lyon1.fr; Fulchiron, R., E-mail: rene.fulchiron@univ-lyon1.fr [Ingénierie des Matériaux Polymères - UMR CNRS 5223, Université de Lyon - Université Lyon 1, Bâtiment POLYTECH Lyon - 15 boulevard Latarjet, 69622, Villeurbanne (France)

    2015-12-17

    The purpose of this study is to understand the influence of the yarn processing on the migration of additives molecules, especially insecticide, within polyethylene (PE) yarns. Yarns were manufactured in the laboratory focusing on three key-steps (spinning, post-stretching and heat-setting). Influence of each step on yarn properties was investigated using tensile tests, differential scanning calorimetry and wide-angle X-ray diffraction. The post-stretching step was proved to be critical in defining yarn mechanical and structural properties. Although a first orientation of polyethylene crystals was induced during spinning, the optimal orientation was only reached by post-stretching. The results also showed that the heat-setting did not significantly change these properties. The presence of additives crystals at the yarn surface was evidenced by scanning-electron microscopy. These studies performed at each yarn production step allowed a detailed analysis of the additives’ ability to migrate. It is concluded that while post-stretching decreased the migration rate, heat-setting seems to boost this migration.

  17. Final Report - Melt Rate Enhancement for High Aluminum HLW Glass Formulation, VSL-08R1360-1, Rev. 0, dated 12/19/08

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A.; Pegg, I. L.; Chaudhuri, M.; Gong, W.; Gan, H.; Matlack, K. S.; Bardakci, T.; Kot, W.

    2013-11-13

    in melter operating temperature. Glass composition development was based on one of the HLW waste compositions specified by ORP that has a high concentration of aluminum. Small-scale tests were used to provide an initial screening of various glass formulations with respect to melt rates; more definitive screening was provided by the subsequent DM100 tests. Glass properties evaluated included: viscosity, electrical conductivity, crystallinity, gross glass phase separation and the 7- day Product Consistency Test (ASTM-1285). Glass property limits were based upon the reference properties for the WTP HLW melter. However, the WTP crystallinity limit (< 1 vol% at 950oC) was relaxed slightly as a waste loading constraint for the crucible melts.

  18. Influence of Insulating Materials on Green Building Rating System Results

    Directory of Open Access Journals (Sweden)

    Fabio Bisegna

    2016-09-01

    Full Text Available This paper analyzes the impact of a change in the thermal insulating material on both the energy and environmental performance of a building, evaluated through two different green building assessment methods: Leadership in Energy and Environmental Design (LEED and Istituto per l’innovazione e Trasparenza degli Appalti e la Compatibilità Ambientale (ITACA. LEED is one of the most qualified rating systems at an international level; it assesses building sustainability thanks to a point-based system where credits are divided into six different categories. One of these is fully related to building materials. The ITACA procedure derives from the international evaluation system Sustainable Building Tool (SBTool, modified according to the Italian context. In the region of Umbria, ITACA certification is composed of 20 technical sheets, which are classified into five macro-areas. The analysis was developed on a residential building located in the central Italy. It was built taking into account the principles of sustainability as far as both structural and technical solutions are concerned. In order to evaluate the influence of thermal insulating material, different configurations of the envelope were considered, replacing the original material (glass wool with a synthetic one (expanded polystyrene, EPS and two natural materials (wood fiber and kenaf. The study aims to highlight how the materials characteristics can affect building energy and environmental performance and to point out the different approaches of the analyzed protocols.

  19. Music Influences Ratings of the Affect of Visual Stimuli

    Directory of Open Access Journals (Sweden)

    Waldie E Hanser

    2013-09-01

    Full Text Available This review provides an overview of recent studies that have examined how music influences the judgment of emotional stimuli, including affective pictures and film clips. The relevant findings are incorporated within a broader theory of music and emotion, and suggestions for future research are offered.Music is important in our daily lives, and one of its primary uses by listeners is the active regulation of one's mood. Despite this widespread use as a regulator of mood and its general pervasiveness in our society, the number of studies investigating the issue of whether, and how, music affects mood and emotional behaviour is limited however. Experiments investigating the effects of music have generally focused on how the emotional valence of background music impacts how affective pictures and/or film clips are evaluated. These studies have demonstrated strong effects of music on the emotional judgment of such stimuli. Most studies have reported concurrent background music to enhance the emotional valence when music and pictures are emotionally congruent. On the other hand, when music and pictures are emotionally incongruent, the ratings of the affect of the pictures will in- or decrease depending on the emotional valence of the background music. These results appear to be consistent in studies investigating the effects of (background music.

  20. Music Influences Hedonic and Taste Ratings in Beer

    Science.gov (United States)

    Reinoso Carvalho, Felipe; Velasco, Carlos; van Ee, Raymond; Leboeuf, Yves; Spence, Charles

    2016-01-01

    The research presented here focuses on the influence of background music on the beer-tasting experience. An experiment is reported in which different groups of customers tasted a beer under three different conditions (N = 231). The control group was presented with an unlabeled beer, the second group with a labeled beer, and the third group with a labeled beer together with a customized sonic cue (a short clip from an existing song). In general, the beer-tasting experience was rated as more enjoyable with music than when the tasting was conducted in silence. In particular, those who were familiar with the band that had composed the song, liked the beer more after having tasted it while listening to the song, than those who knew the band, but only saw the label while tasting. These results support the idea that customized sound-tasting experiences can complement the process of developing novel beverage (and presumably also food) events. We suggest that involving musicians and researchers alongside brewers in the process of beer development, offers an interesting model for future development. Finally, we discuss the role of attention in sound-tasting experiences, and the importance that a positive hedonic reaction toward a song can have for the ensuing tasting experience. PMID:27199862

  1. The influence of heterogeneous nucleation on the surface crystallization of guaifenesin from melt extrudates containing Eudragit L10055 or Acryl-EZE.

    Science.gov (United States)

    Bruce, Caroline D; Fegely, Kurt A; Rajabi-Siahboomi, Ali R; McGinity, James W

    2010-05-01

    The objective of this study was to investigate the influence of talc and humidity conditions during storage on the crystal growth of guaifenesin on the surface of melt-extruded matrix tablets. Tablets consisted of the model drug guaifenesin in a matrix of either Acryl-EZE(R) or Eudragit(R) L10055 and either no talc, 25% or 50% talc. After processing, the hot-melt-extruded matrix tablets were supersaturated with amorphous guaifenesin, which resulted in the development of guaifenesin drug crystals on exposed surfaces of the tablet during storage (all tablets were stored at 24 degrees C). A previously developed, quantitative test was used to assay for surface guaifenesin. In tablets with a drug-to-polymer ratio of 19:81, talc-containing tablets exhibited an earlier onset of crystal growth (storage at 17% relative humidity). The presence of talc also increased the amount of surface crystallization and was independent of the talc concentration, since the talc levels used in this study exceeded the critical nucleant concentration. Additional non-melting components did not have an additive effect on surface crystal growth. High humidity during storage (78%) increased guaifenesin crystallization, but moisture uptake of tablets did not correlate with increased drug recrystallization. When storage at 17% relative humidity was interrupted for 3days by storage at 78% relative humidity before the tablets were returned to their previous low RH storage conditions, crystal growth quickly increased during the high RH interval and remained at an elevated level throughout the remaining storage period. A similar intermediate period of low, 17% relative humidity in tablets stored before and after that time at 78% RH did not affect surface crystallization levels. The effects of humidity and talc on the crystallization of guaifenesin from melt-extruded dosage forms supersaturated with amorphous drug were ascribed to heterogeneous nucleation.

  2. MULTIPLE MELTING IN NYLON 1010

    Institute of Scientific and Technical Information of China (English)

    FU Shuren; CHEN Taoyung

    1983-01-01

    Multiple melting behavior of nylon 1010 has been investigated by using DSC instrument. Effects of partial scanning, partial scanning and annealing, heating rate, cooling rate and stepwise annealing on the melting curve were studied. Experimental results indicate that the sample undergoes a process of continuous melting and recrystallization during DSC scanning. Nylon 1010 contains a distribution of crystallites of different degrees of perfection which is strongly dependent on its previous thermal history. From the structural reorganization point of view, the origin of double and multiple peaks of the melting curve is explained.

  3. Production rate estimation of mycosporine-like amino acids in two Arctic melt ponds by stable isotope probing with NAH(13) CO3.

    Science.gov (United States)

    Ha, Sun-Yong; Min, Jun-Oh; Joo, Hyun Min; Chung, Kyung Ho; Shin, Kyung-Hoon; Yang, EunJin; Kang, Sung-Ho

    2014-10-01

    The net carbon uptake rate and net production rate of mycosporine-like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a (13) C stable isotope tracer technique. The Research Vessel Araon visited ice-covered western-central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.24 mg C · m(-3) · h(-1) (SD = ±1.12 mg C · m(-3) · h(-1) ), while that in the open MP was 1.3 mg C · m(-3) · h(-1) (SD = ±0.05 mg C · m(-3) · h(-1) ). The net production rate of total MAAs in incubated PC bottles was highest (1.44 (SD = ±0.24) ng C · L(-1) · h(-1) ) in the open MP and lowest (0.05 (SD = ±0.003) ng C · L(-1) · h(-1) ) in the closed MP. The net production rate of shinorine and palythine in incubated PC bottles at the open MP presented significantly high values 0.76 (SD = ±0.12) ng C · L(-1) · h(-1) and 0.53 (SD = ±0.06) ng C · L(-1) · h(-1) . Our results showed that high net production rate of MAAs in the open MP was enhanced by a combination of osmotic and UVR stress and that in situ net production rates of individual MAA can be determined using (13) C tracer in MPs in Arctic sea ice.

  4. The influence of Greenland melt water on climate during past and future warm periods: a model study

    Science.gov (United States)

    Blaschek, Michael; Bakker, Pepijn; Renssen, Hans

    2013-04-01

    "Can past climates teach us something about the future?" Under this general question of interest to most palaeoclimate-modeller we specified it more to "Can past changes in the strength of the Atlantic Meridional Overturning Circulation (AMOC) related to melt water from the Greenland Ice Sheet (GIS) teach us something about future changes in the AMOC forced by predicted partial melting of the GIS?" To address this question, we developed a series of sensitivity experiments with the global atmosphere-ocean-sea-ice model LOVECLIM to better understand the relationship between the strength of the Atlantic Meridional Overturning Circulation (AMOC) and Greenland Ice Sheet (GIS) melt over the last and present interglacials (the Eemian and the Holocene, respectively) and put these into perspective of future greenhouse gas emission scenarios. In terms of radiative forcing, future emission scenarios are different from past orbitally-forced warm periods, as past insolation varied per season and per latitude, whereas radiative forcing due to future greenhouse gas emissions has no seasonal component (i.e. it is an annual forcing) and shows little variation per latitude. However, the two can be compared when we consider the radiative forcing regimes of the different considered warm climates, by focusing on the energy that is potentially available from radiative forcing to melt the GIS. In a similar approach, Swingedouw et al. (2009) have shown in simulations with an AOGCM that the AMOC sensitivity relates non-linear to freshwater input and that under Last Glacial Maximum (LGM) conditions the climate is more sensitive compared to warmer climates. They conclude that different climatic conditions share similar patterns in response and that past climates are useful for models to evaluate their abilities in reproducing past events. The authors encourage further model sensitivity testing to gain a better understanding of this highly important question. In order to test this approach we

  5. The influence of guaifenesin and ketoprofen on the properties of hot-melt extruded polyethylene oxide films.

    Science.gov (United States)

    Crowley, Michael M; Fredersdorf, Anke; Schroeder, Britta; Kucera, Shawn; Prodduturi, Suneela; Repka, Michael A; McGinity, James W

    2004-08-01

    Films containing polyethylene oxide (PEO) and a model drug, either guaifenesin (GFN) or ketoprofen (KTP), were prepared by hot-melt extrusion. The thermal properties of the hot-melt extruded films were investigated using differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) was used to examine the surface morphology of the films, and wide angle X-ray diffraction (XRD) was used to investigate the crystalline properties of the polymer, drugs and physical mixtures as well as the solid state structure of the films. The stability of the polymer was studied using gel permeation chromatography. The mechanical properties, including percent elongation and tensile strength of the films, were determined on an Instron according to American Society for Testing Materials (ASTM) procedures. The Hansen solubility parameter was calculated using the Hoftyzer or van Krevelen method to estimate the likelihood of drug--polymer miscibility. Both GFN and KTP were stable during the extrusion process. Melting points corresponding to the crystalline drugs were not observed in the films. Crystallization of GFN on the surface of the film was observed at all concentrations studied, however KTP crystallization did not occur until reaching the 15% level. Guaifenesin and ketoprofen were found to decrease drive load, increase PEO stability and plasticize the polymer during extrusion. The Hansen solubility parameters predicted miscibility between PEO and KTP and poor miscibility between PEO and GFN. The predictions of the solubility parameters were in agreement with the XRD and SEM results. The percent elongation decreased with increasing GFN concentrations and significantly increased with increasing levels of KTP. Both GFN and KTP decreased the tensile strength of the extruded film.

  6. Modeling the Influence of Antifreeze Proteins on Three-Dimensional Ice Crystal Melt Shapes using a Geometric Approach

    CERN Document Server

    Liu, Jun Jie; Dolev, Maya Bar; Celik, Yeliz; Wettlaufer, J S; Braslavsky, Ido

    2012-01-01

    The melting of pure axisymmetric ice crystals has been described previously by us within the framework of so-called geometric crystal growth. Nonequilibrium ice crystal shapes evolving in the presence of hyperactive antifreeze proteins (hypAFPs) are experimentally observed to assume ellipsoidal geometries ("lemon" or "rice" shapes). To analyze such shapes we harness the underlying symmetry of hexagonal ice Ih and extend two-dimensional geometric models to three-dimensions to reproduce the experimental dissolution process. The geometrical model developed will be useful as a quantitative test of the mechanisms of interaction between hypAFPs and ice.

  7. Liquidus temperatures of komatiites and the effect of cooling rate on element partitioning between olivine and komatiitic melt

    Science.gov (United States)

    Sossi, Paolo A.; O'Neill, Hugh St. C.

    2016-05-01

    Archean komatiites are the hottest magmas preserved on Earth and are thus unique probes of its thermal evolution. Estimating their eruption temperatures remains problematic, however, because the uppermost (A1, A2) zones of komatiite flows contain randomly oriented spinifex-textured olivines, indicative of rapid cooling and growth. Fe-Mg partitioning between olivine and assumed komatiitic liquid typically shows departures from equilibrium, extending towards higher K_{{D}}^{{{{Fe}}^{2 + } - {{Mg}}}}. If these higher values are a disequilibrium effect, using them to calculate parental magma composition would lead to errors in estimated liquidus temperatures. In order to investigate this possibility, we have performed experiments on two komatiite compositions, the classic Barberton Aluminium Undepleted Komatiite (AUK) sample 49J (32.2 % MgO) and Munro AUK sample 422/95 (23 % MgO). Isothermal experiments to constrain phase equilibria on 49J at atmospheric pressure, between 1360 and 1600 °C at 1.7 log units below and 1.1 above the fayalite-magnetite-quartz (FMQ) buffer reveal a liquidus temperature ( T liq) of 1616 °C, 40 °C lower than a previous estimate. The K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} ranges between 0.320 and 0.295 at FMQ - 1.7, with a slight negative dependence on temperature. To replicate the conditions that prevailed during the quenching of komatiites in their upper chill zones, experiments with a constant cooling rate at FMQ - 1.7 were performed on 422/95 ( T liq = 1450 °C) at 0.5, 1.5, 2.5, 6.5 and 16 °C/min. Olivine morphology changes from euhedral to tabular at low cooling rates, hopper at intermediate, and skeletal and chain structures at high rates. Concurrently, the K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} increases monotonically from an equilibrium value of 0.305 to 0.376 at 16 °C/min, reflecting the inability of unwanted cations to diffuse away from the growing olivine. The high K_{{D}}^{{Σ {{Fe}}{-}{{Mg}}}} between olivine and komatiitic liquid caused by

  8. Influence of Immersion Conditions on The Tensile Strength of Recycled Kevlar®/Polyester/Low-Melting-Point Polyester Nonwoven Geotextiles through Applying Statistical Analyses

    Directory of Open Access Journals (Sweden)

    Jing-Chzi Hsieh

    2016-05-01

    Full Text Available The recycled Kevlar®/polyester/low-melting-point polyester (recycled Kevlar®/PET/LPET nonwoven geotextiles are immersed in neutral, strong acid, and strong alkali solutions, respectively, at different temperatures for four months. Their tensile strength is then tested according to various immersion periods at various temperatures, in order to determine their durability to chemicals. For the purpose of analyzing the possible factors that influence mechanical properties of geotextiles under diverse environmental conditions, the experimental results and statistical analyses are incorporated in this study. Therefore, influences of the content of recycled Kevlar® fibers, implementation of thermal treatment, and immersion periods on the tensile strength of recycled Kevlar®/PET/LPET nonwoven geotextiles are examined, after which their influential levels are statistically determined by performing multiple regression analyses. According to the results, the tensile strength of nonwoven geotextiles can be enhanced by adding recycled Kevlar® fibers and thermal treatment.

  9. Surface deformation versus eruption rates of the two Eyjafjallajökull 2010 eruptions; implications for the magma plumbing system and origin of melts

    Science.gov (United States)

    Pedersen, R.; Sigmundsson, F.; Hreinsdottir, S.; Arnadottir, T.; Hoskuldsson, A.; Gudmundsson, M. T.; Magnusson, E.

    2010-12-01

    eruption rate. A pronounced peak in eruptive activity around May 5 is associated with a halt in volcano deflation and temporary renewed inflation. Finally, subsidence continued several weeks beyond the end of the eruption. Interpretations of the temporal and spatial variations of the observed deformation rates and associated eruption rates are not straightforward. When gathering information from several sources, e.g. geochemistry, seismicity, and geodesy, there is a strong indication that substantial magma replenishment of primitive melts originating at great depths occurred during the eruption. Other processes such as the evolved magma generation and extraction process as well as thermo-elastic responses in the sill intrusion region may need to be taken into account to better explain the relationship between volume changes inferred from geodetic data and estimates of the eruptive volume.

  10. The role of the amorphous phase in melting of linear UHMW-PE; implications for chain dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Rastogi, Sanjay [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Lippits, Dirk R [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Hoehne, Guenther W H [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Mezari, Brahim [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands); Magusin, Pieter C M M [Department of Chemical Engineering and Chemistry/Dutch Polymer Institute, Eindhoven University of Technology, PO Box 513, 5600MB Eindhoven (Netherlands)

    2007-05-23

    In ultra-high molecular weight polyethylene (UHMW-PE), it is possible to obtain single chain forming single crystals, where chains are adjacently re-entrant. Depending on the heating rate, it is feasible to melt these crystals either by simple consecutive detachment of chain stems from the crystalline substrate or by cluster melting, where several chain stems are involved. The consecutive detachment of chain stems occurs at the melting point predicted from the Gibbs-Thomson equation, whereas the cluster melting at much higher temperatures. Melting by the consecutive detachment of chain stems from the crystal substrate and their diffusion in the melt ultimately result in a new melt state having a heterogeneous distribution of physical entanglements, which invokes differences in local mobility. With combined DSC, rheology and solid-state NMR studies, it is concluded that the disentangled domains present within the entangled matrix possess higher local mobility than the entangled domains, ultimately causing lower elastic modulus. The fraction of the entangled and disentangled domains is maintained at higher temperatures, leading to a thermodynamically non-equilibrium melt state. In contrast, in cluster melting, where several chain stems (initially disentangled) can simultaneously adopt the random coil state, entanglements that are formed are homogeneously distributed in the melt. The paper invokes the influence of the topological differences present in the amorphous phase of the semi-crystalline polymer on the melting kinetics of crystals. The reported findings have implications for the melting behaviour and the resulting melt state of polymers in general.

  11. Air-sea flux of CO2 in arctic coastal waters influenced by glacial melt water and sea ice

    DEFF Research Database (Denmark)

    Sejr, Mikael Kristian; Krause-Jensen, Dorte; Rysgaard, Søren

    2011-01-01

    and thereby efficiently blocked air–sea CO2 exchange. During sea ice melt, dissolution of CaCO3 combined with primary production and strong stratification of the water column acted to lower surface-water pCO2 levels in the fjord. Also, a large input of glacial melt water containing geochemically reactive......Annual air–sea exchange ofCO2 inYoung Sound,NEGreenlandwas estimated using pCO2 surface-water measurements during summer (2006–2009) and during an ice-covered winter 2008. All surface pCO2 values were below atmospheric levels indicating an uptake of atmospheric CO2. During sea ice formation......, dissolved inorganic carbon (DIC) content is reduced causing sea ice to be under saturated in CO2. Approximately 1% of the DIC forced out of growing sea ice was released into the atmosphere while the remaining 99% was exported to the underlying water column. Sea ice covered the fjord 9 months a year...

  12. Nucleation behavior of melted Bi films at cooling rates from 10{sup 1} to 10{sup 4} K/s studied by combining scanning AC and DC nano-calorimetry techniques

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Kechao; Vlassak, Joost J., E-mail: vlassak@esag.harvard.edu

    2015-03-10

    Highlights: • We proposed a general data reduction scheme that combines scanning AC and DC calorimetry results for the study of reaction kinetics. • Calorimetry measurements at cooling rates ranging from 30 K/s to 20,000 K/s were achieved. • Upon initial melting, the Bi thin-film sample breaks up into thousands of isolated islands, and highly repeatable nucleation behavior is observed. • The nucleation rate of melted Bi is calculated, which can be well described by classical nucleation theory over a wide range of cooling rates. - Abstract: We study the nucleation behavior of undercooled liquid Bi at cooling rates ranging from 10{sup 1} to 10{sup 4} K/s using a combination of scanning DC and AC nano-calorimetry techniques. Upon initial melting, the Bi thin-film sample breaks up into silicon nitride-coated isolated islands. The number of islands in a typical sample is sufficiently large that highly repeatable nucleation behavior is observed, despite the stochastic nature of the nucleation process. We establish a data reduction technique to evaluate the nucleation rate from DC and AC calorimetry results. The results show that the driving force for the nucleation of melted Bi is well described by classical nucleation theory over a wide range of cooling rates. The proposed technique provides a unique and efficient way to examine nucleation kinetics with cooling rates over several orders of magnitude. The technique is quite general and can be used to evaluate reaction kinetics in other materials.

  13. Channelling of Melt Above Plumes and Beneath MORs

    Science.gov (United States)

    Mueller, K.; Schmeling, H.

    2003-12-01

    We investigate melt transportation in partially molten rocks under different stress fields above the head of a mantle plume or beneath a spreading mid-oceanic ridge under hydrous and anhydrous conditions. We model such aggregates with the 2D-FD code FDCON [1] by means of a porous deformable matrix with melt under the influence of a given stress field to clarify the following key questions: Could channeling occur in a matrix containing a random melt distribution under a given stress field? Which orientation does it take? Is it possible to achieve a focusing of melt towards a MOR (dykes)? Does applying simple or pure shear to the matrix result in a difference in the formation and orientation of channels? How does the channel instability evolve during finite simple shear? In a deforming partially molten aggregate, weakening of the solid matrix due to the presence of melt creates an instability in which melt is localized by the following mechanism: regions of initially high melt fraction are areas of low viscosity and pressure, so that melt is drawn into these regions from higher pressure surroundings. This further enhances the melt weakening, producing a self-excited localization mechanism [2]. The channeling developing in models with a random melt distribution of 3.5 +/- 0.5% shows that melt is accumulated preferably in inclined channels. For both, simple as well as pure shear, the growth rate is highest for an orientation parallel to the direction of the maximum compressive stress and proportional to applied stress and the reverse of the Melt Retention Number. This also confirms the theoretical growth rate found by Stevenson [2]. In our isothermal models we found that the influence of water reduces the growth rate, in contrast to non-isothermal models of Hall [3]. Under simple shear melt channels evolve from an irregular melt distribution at angles of 45 degrees to the direction of shear. Upon further straining they rotate out of the orientation of maximum growth

  14. MELTED BUTTER TECHNOLOGY DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    L. V. Golubeva

    2014-01-01

    Full Text Available Summary. Melted butter is made from dairy butter by rendering the fat phase. It has specific taste and aroma, high-calorie content and good assimilability. Defects of butter which appeared during the storage causes by the development of microbiological processes or by the chemical oxidation. On the development of these processes influence quality and composition of fresh butter, its physical structure, content of the increased amount of gas phase and content of heavy metals, storage conditions. Microbiological spoilage of butter occurs generally due to damage of plasma which is good environment for the development of microorganisms. Defects of microbiological origin include: unclean, sour, moldy, yeasty, cheesy, bitter taste. Defects of test and smell chemical origin are formed due to hydrolytic digestion of lipids. It's prevailed at long storage of butter in the conditions of freezing temperatures. It's picked out the following main processes of spoiling: souring, acidifying and sallowness. Often these processes take place simultaneously.It has been investigated melted butter with lactated additive. The latter improves the microbiological and toxicological safety, prolongs the storage condition of the products. Technological efficiency of the additives is achieved by a multilayer products formation from the inactive bound water, preventing microorganisms growth and by the barrier layer with lactate inhibiting hydrolytic reactions. Oil samples were obtained with the batch-type butter maker application, then they were melted and after that lactated additive were supplemented. It has been studied organoleptic and physico-chemical indices of the melted butter samples. The fatty-acid composition of melted butter were studied. Comparative analysis of fatty-acid composition of cow's milk fat and produced melted butter has shown their similarity. Also in the last sample there is increased weight fraction of linoleic and linolenic acids. The obtained

  15. Influence of recirculation rate on the performance of a combined ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    2016-09-14

    Sep 14, 2016 ... parameters that influence biological nitrogen removal,. *Corresponding author. ... anaerobic-aerobic reactor configuration for the treatment of wastewater from the industrial processing of lysine. They observed that the best ...

  16. The influence of drug physical state on the dissolution enhancement of solid dispersions prepared via hot-melt extrusion: a case study using olanzapine.

    Science.gov (United States)

    Pina, Maria Fátima; Zhao, Min; Pinto, João F; Sousa, João J; Craig, Duncan Q M

    2014-04-01

    In this study, we examine the relationship between the physical structure and dissolution behavior of olanzapine (OLZ) prepared via hot-melt extrusion in three polymers [polyvinylpyrrolidone (PVP) K30, polyvinylpyrrolidone-co-vinyl acetate (PVPVA) 6:4, and Soluplus® (SLP)]. In particular, we examine whether full amorphicity is necessary to achieve a favorable dissolution profile. Drug–polymer miscibility was estimated using melting point depression and Hansen solubility parameters. Solid dispersions were characterized using differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. All the polymers were found to be miscible with OLZ in a decreasing order of PVP>PVPVA>SLP. At a lower extrusion temperature (160°C), PVP generated fully amorphous dispersions with OLZ, whereas the formulations with PVPVA and SLP contained 14%-16% crystalline OLZ. Increasing the extrusion temperature to 180°C allowed the preparation of fully amorphous systems with PVPVA and SLP. Despite these differences, the dissolution rates of these preparations were comparable, with PVP showing a lower release rate despite being fully amorphous. These findings suggested that, at least in the particular case of OLZ, the absence of crystalline material may not be critical to the dissolution performance. We suggest alternative key factors determining dissolution, particularly the dissolution behavior of the polymers themselves.

  17. Influence of Cooling Rate on Microsegregation Behavior of Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Md. Imran Khan

    2014-01-01

    Full Text Available The effect of cooling rate on microstructure and microsegregation of three commercially important magnesium alloys was investigated using Wedge (V-shaped castings of AZ91D, AM60B, and AE44 alloys. Thermocouples were distributed to measure the cooling rate at six different locations of the wedge casts. Solute redistribution profiles were drawn based on the chemical composition analysis obtained by EDS/WDS analysis. Microstructural and morphological features such as dendrite arm spacing and secondary phase particle size were analyzed using both optical and scanning electron microscopes. Dendritic arm spacing and secondary phase particle size showed an increasing trend with decreasing cooling rate for the three alloys. Area percentage of secondary phase particles decreased with decreasing cooling rate for AE44 alloy. The trend was different for AZ91D and AM60B alloys, for both alloys, area percentage of β-Mg17Al12 increased with decreasing cooling rate up to location 4 and then decreased slightly. The tendency for microsegregation was more severe at slower cooling rates, possibly due to prolonged back diffusion. At slower cooling rate, the minimum concentration of aluminum at the dendritic core was lower compared to faster cooled locations. The segregation deviation parameter and the partition coefficient were calculated from the experimentally obtained data.

  18. Can mock interviewers' personalities influence their personality ratings of applicants?

    Science.gov (United States)

    Hilliard, Thomas; Macan, Therese

    2009-03-01

    The authors examined individual difference and self-regulatory variables to understand how an interviewer rates a candidate's personality. Participants were undergraduate students at a large midwestern university in the United States who completed measures of individual differences, read an employment interview transcript involving a candidate applying for a customer service job, and rated the candidate's personality. Participants' agreeableness, social skills, and communion striving were positively associated with their ratings of the candidate's helpfulness and obedience. The authors provide a foundation for further research on interviewer effectiveness and the processes underlying the employment interview.

  19. Influence of Gas Flow Rate on the Deposition Rate on Stainless Steel 202 Substrates

    Directory of Open Access Journals (Sweden)

    M.A. Chowdhury

    2012-12-01

    Full Text Available Solid thin films have been deposited on stainless steel 202 (SS 202 substrates at different flow rates of natural gas using a hot filament thermal chemical vapor deposition (CVD reactor. In the experiments, the variations of thin film deposition rate with the variation of gas flow rate have been investigated. The effects of gap between activation heater and substrate on the deposition rate have also been observed. Results show that deposition rate on SS 202 increases with the increase in gas flow rate within the observed range. It is also found that deposition rate increases with the decrease in gap between activation heater and substrate. In addition, friction coefficient and wear rate of SS 202 sliding against SS 304 under different sliding velocities are also investigated before and after deposition. The experimental results reveal that improved friction coefficient and wear rate is obtained after deposition than that of before deposition.

  20. Research on Influences of Converter Transformer on DC Ice-Melting Device%换流变压器在直流融冰装置中的作用研究

    Institute of Scientific and Technical Information of China (English)

    何鹏飞; 王渝红; 李兴源; 魏巍; 李思思; 邹家勇; 吴怡敏; 何琰

    2012-01-01

    DC ice melting is one of the most mature and feasible ice melting methods. Based on existing DC ice-melting technology and by means of researching minimum ice-melting current and ice-melting power of DC ice-melting and the action of harmonic voltages, the influences of using or not making use of converter transformer on both DC ice-melting device and AC transmission line are analyzed to provide a new thinking of applying DC ice-melting. Combining with a certain ice-melting item of Sichuan power grid, the conditions of whether converter transformer could be applied in engineering practice are obtained by PSCAD/EMTD simulation. Results of PSCAD/EMTD simulation show that when the length of the transmission line to be ice-melted is short and the needed ice-melting current is not too high, the converter transformer could be not utilized to reduce the investment for the ice-melting device and ensure secure and stable operation of power grid; when the length of the transmission line to be ice-melted is long and the larger DC voltage drop is needed, the converter transformer should be utilized to adjust the firing angle and reduce reactive power loss.."%直流融冰是目前最为成熟和可行的融冰手段之一.文章在现有直流融冰技术的基础上,通过对直流融冰的最小融冰电流、直流融冰功率以及谐波电压的研究,分析使用和不使用换流变压器对直流融冰装置和交流线路的影响,为直流融冰的应用提供了一个新的思路.结合四川电网某融冰工程项目,使用PSCAD/EMTDC软件仿真得出使用换流变压器的工程实际应用条件和限制范围,研究成果成功应用在四川电网直流融冰项目设计工作中,可供今后工程参考.

  1. Influence of some formulation and process parameters on the stability of lysozyme incorporated in corn flour- or corn starch-based extruded materials prepared by melt blending processing.

    Science.gov (United States)

    Jbilou, Fouzia; Galland, Sophie; Telliez, Camille; Akkari, Zied; Roux, Roselyne; Oulahal, Nadia; Dole, Patrice; Joly, Catherine; Degraeve, Pascal

    2014-12-01

    In order to obtain an antimicrobial biodegradable material, corn flour was extruded with 1% of lysozyme. Since the limited stability of natural preservatives such as lysozyme is a common bottleneck to the elaboration of active biomaterials by melt blending processes, the influence of formulation and of extrusion processing temperature on its residual enzymatic activity was investigated. To assess the contribution of process parameters such as temperature, shear stress and of related formulation parameters such as glycerol and moisture contents, the stability of lysozyme following its extrusion or its thermoforming with plasticized corn starch or thermal treatments in aqueous glycerol solutions was also studied. Increasing glycerol content from 25% to 30% significantly limited inactivation of lysozyme during extrusion, while increasing initial moisture content of the mixture from 14.5% to 28.5% had the opposite effect. These observations open the possibility to prepare active materials retaining more than 60±7% of initial lysozyme activity.

  2. Music Influences Ratings of the Affect of Visual Stimuli

    OpenAIRE

    Waldie E Hanser; Mark, Ruth E

    2013-01-01

    This review provides an overview of recent studies that have examined how music influences the judgment of emotional stimuli, including affective pictures and film clips. The relevant findings are incorporated within a broader theory of music and emotion, and suggestions for future research are offered.Music is important in our daily lives, and one of its primary uses by listeners is the active regulation of one's mood. Despite this widespread use as a regulator of mood and its general pervas...

  3. Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

    Science.gov (United States)

    Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

    2015-01-15

    The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles.

  4. Influence of cell shape on mechanical properties of Ti-6Al-4V meshes fabricated by electron beam melting method.

    Science.gov (United States)

    Li, S J; Xu, Q S; Wang, Z; Hou, W T; Hao, Y L; Yang, R; Murr, L E

    2014-10-01

    Ti-6Al-4V reticulated meshes with different elements (cubic, G7 and rhombic dodecahedron) in Materialise software were fabricated by additive manufacturing using the electron beam melting (EBM) method, and the effects of cell shape on the mechanical properties of these samples were studied. The results showed that these cellular structures with porosities of 88-58% had compressive strength and elastic modulus in the range 10-300MPa and 0.5-15GPa, respectively. The compressive strength and deformation behavior of these meshes were determined by the coupling of the buckling and bending deformation of struts. Meshes that were dominated by buckling deformation showed relatively high collapse strength and were prone to exhibit brittle characteristics in their stress-strain curves. For meshes dominated by bending deformation, the elastic deformation corresponded well to the Gibson-Ashby model. By enhancing the effect of bending deformation, the stress-strain curve characteristics can change from brittle to ductile (the smooth plateau area). Therefore, Ti-6Al-4V cellular solids with high strength, low modulus and desirable deformation behavior could be fabricated through the cell shape design using the EBM technique. Copyright © 2014 Acta Materialia Inc. All rights reserved.

  5. Influence of corruption on economic growth rate and foreign investment

    Science.gov (United States)

    Podobnik, Boris; Shao, Jia; Njavro, Djuro; Ivanov, Plamen Ch.; Stanley, H. E.

    2008-06-01

    We analyze the dependence of the Gross Domestic Product ( GDP) per capita growth rates on changes in the Corruption Perceptions Index ( CPI). For the period 1999 2004 for all countries in the world, we find on average that an increase of CPI by one unit leads to an increase of the annual GDP per capita growth rate by 1.7%. By regressing only the European countries with transition economies, we find that an increase of CPI by one unit generates an increase of the annual GDP per capita growth rate by 2.4%. We also analyze the relation between foreign direct investments received by different countries and CPI, and we find a statistically significant power-law functional dependence between foreign direct investment per capita and the country corruption level measured by the CPI. We introduce a new measure to quantify the relative corruption between countries based on their respective wealth as measured by GDP per capita.

  6. Search strategy has influenced the discovery rate of human viruses.

    Science.gov (United States)

    Rosenberg, Ronald; Johansson, Michael A; Powers, Ann M; Miller, Barry R

    2013-08-20

    A widely held concern is that the pace of infectious disease emergence has been increasing. We have analyzed the rate of discovery of pathogenic viruses, the preeminent source of newly discovered causes of human disease, from 1897 through 2010. The rate was highest during 1950-1969, after which it moderated. This general picture masks two distinct trends: for arthropod-borne viruses, which comprised 39% of pathogenic viruses, the discovery rate peaked at three per year during 1960-1969, but subsequently fell nearly to zero by 1980; however, the rate of discovery of nonarboviruses remained stable at about two per year from 1950 through 2010. The period of highest arbovirus discovery coincided with a comprehensive program supported by The Rockefeller Foundation of isolating viruses from humans, animals, and arthropod vectors at field stations in Latin America, Africa, and India. The productivity of this strategy illustrates the importance of location, approach, long-term commitment, and sponsorship in the discovery of emerging pathogens.

  7. Impact Strength and Flow Melt Flow Rate of High Density Polyethylene Melts%高密度聚乙烯共混物的抗冲击强度与熔体流动速率

    Institute of Scientific and Technical Information of China (English)

    廖华勇; 陶国良

    2013-01-01

    Four high density polyethylene blends (HDPE 8916/5000S,HDPE 9641/5000S,HDPE 5306/5000S and HDPE 8916/6003T) were prepared.The notch impact strength σin and melt flow rate(MFR) were measured,and their relation was investigated.The results show that the notch impact strength σin drops with the increase of MFR,the σin-MFR curve meets the law of exponential decay.The area of σin-MFR curve surrounded by coordinate axes is the highest for HDPE 5306/HDPE5000S blend,which suggests it is the easiest for HDPE 5306/HDPE5000S blend to meet the notch impact strength and MFR requirement.Then HDPE 5306/HDPE5000S blend was toughened by adding polyolefin elastomer (POE).The results show when the mass ratio of HDPE 5306/ HDPE5000S/POE is 28.5/66.5/5,the notch impact strength σin arrives 42.88 kJ/m2 and the MFR is 2.64 g/10min (230℃,2.16kg),much higher than of HDPE 5306/HDPE5000S (30/70,mass ratio,similarly hereinafter),28.16 kJ/m2 and 2.55 g/10min(230℃,2.16kg),respectively.%制备了4种高密度聚乙烯(HDPE) HDPE 8916/5000S、HDPE 9641/5000S、HDPE 5306/5000S和HDPE 8916/6003T共混物,并测试其缺口冲击强度σin和熔体流动速率(MFR),探讨了两者之间的关系.结果表明,随着MFR的增加,缺口冲击强度逐渐下降,两者之间符合指数衰减规律.而其中HDPE 5306/HDPE5000S的σin-MFR曲线与坐标轴之间包围的面积最大,比其它3种共混物更容易实现同时满足冲击强度和流动性的要求.文中还对HDPE 5306/HDPE5000S共混物用乙烯-辛烯共高聚物(POE)进行增韧改性.结果表明,当HDPE 5306/HDPE5000S/POE的质量比为28.5/66.5/5时,缺口冲击强度达到42.88kJ/m2,高于HDPE 5306/HDPE5000S(30/70,质量比,下同)时的28.16kJ/m2,而POE增韧后共混物的MFR为2.64 g/10min(230℃,2.16kg),比HDPE 5306/HDPE5000S(30/70)时的MFR值2.55g/10min(230℃,2.16kg)高.

  8. Variability in Shipboard Morbidity Rates: Environmental and Occupational Influences.

    Science.gov (United States)

    1976-09-01

    relate significantly to illness rates during overseas deployments. 1 ,2 ,3 *From the Environmental and Social Medicine Division, Naval Health Research...Center, San Diego, California 92152. iHead, Environmental and Social Medicine Division. 2Psychology Technician, Fleet Medicine Branch, Environmental and... Social Medicine Division. 0 k W4 ~~;’:r4 ,: ,l cl :-on Important questions remain concerning environmental and occupational determi- nants of

  9. Influence of the dose rate in the PVDF degradation processes

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Gual, Maritza R., E-mail: maritzargual@gmail.com [Instituto Superior de Tecnologias y Ciencias Aplicadas (InsTEC), Departamento de Ingenieria Nuclear, La Habana (Cuba); Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from gamma radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation by products such as peroxide degradation. Radiation cross-linking technologies include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, polymer recycling, hydrogels etc. The degradation of PVDF polymer exposed to gamma irradiation in oxygen atmosphere in high dose rate has been studied and compared to obtained under smaller dose rates. The samples were irradiated with a Co-60 source at constant dose rate (12 kGy/h and 2,592 kGy/h), with doses ranging from 100 kGy to 3,000 kGy. Different dose rate determine the prevalence of the processes being evaluated in this work by thermal measurements and infrared spectroscopy. It is shown that the degradation processes involve chain scissions and crosslink formation. The formation of oxidation products was shown at the surface of the irradiated film. The FTIR data revealed absorption bands at 1730 and 1853 cm{sup -1} which were attributed to the stretch of C=O bonds, at 1715 and 1754 cm{sup -1} which were attributed to the C=C stretching and at 3518, 3585 and 3673 cm{sup -1} which were associated with NH stretch of NH{sub 2} and OH. Thermogravimetric studies reveal that the irradiation induced the increasing residues and decrease of the temperature of the decomposition start. (author)

  10. Influence of Conformational Entropy on the Protein Folding Rate

    Directory of Open Access Journals (Sweden)

    Oxana V. Galzitskaya

    2010-04-01

    Full Text Available One of the most important questions in molecular biology is what determines folding pathways: native structure or protein sequence. There are many proteins that have similar structures but very different sequences, and a relevant question is whether such proteins have similar or different folding mechanisms. To explain the differences in folding rates of various proteins, the search for the factors affecting the protein folding process goes on. Here, based on known experimental data, and using theoretical modeling of protein folding based on a capillarity model, we demonstrate that the relation between the average conformational entropy and the average energy of contacts per residue, that is the entropy capacity, will determine the possibility of the given chain to fold to a particular topology. The difference in the folding rate for proteins sharing more ball-like and less ball-like folds is the result of differences in the conformational entropy due to a larger surface of the boundary between folded and unfolded phases in the transition state for proteins with a more ball-like fold. The result is in agreement with the experimental folding rates for 67 proteins. Proteins with high or low side chain entropy would have extended unfolded regions and would require some additional agents for complete folding. Such proteins are common in nature, and their structural properties are of biological importance.

  11. Influence of birth rates and transmission rates on the global seasonality of rotavirus incidence.

    Science.gov (United States)

    Pitzer, Virginia E; Viboud, Cécile; Lopman, Ben A; Patel, Manish M; Parashar, Umesh D; Grenfell, Bryan T

    2011-11-07

    Rotavirus is a major cause of mortality in developing countries, and yet the dynamics of rotavirus in such settings are poorly understood. Rotavirus is typically less seasonal in the tropics, although recent observational studies have challenged the universality of this pattern. While numerous studies have examined the association between environmental factors and rotavirus incidence, here we explore the role of intrinsic factors. By fitting a mathematical model of rotavirus transmission dynamics to published age distributions of cases from 15 countries, we obtain estimates of local transmission rates. Model-predicted patterns of seasonal incidence based solely on differences in birth rates and transmission rates are significantly correlated with those observed (Spearman's ρ = 0.65, p rates and transmission rates and explore how vaccination may impact these patterns. Our results suggest that the relative lack of rotavirus seasonality observed in many tropical countries may be due to the high birth rates and transmission rates typical of developing countries rather than being driven primarily by environmental conditions. While vaccination is expected to decrease the overall burden of disease, it may increase the degree of seasonal variation in the incidence of rotavirus in some settings.

  12. Electrical Conductivity of Cryolite Melts

    Science.gov (United States)

    Fellner, P.; Grjotheim, K.; Kvande, H.

    1985-11-01

    This paper proposes an equation for the electrical conductivity of multicomponent cryolite-based mixtures. The equation is based on a physical model which assumes that the conductivity is proportional to the number density of the effective electric charges in the melt. The various authors in the available literature show a great discrepancy in conductivity data of cryolite-based melts. The equation based on the physical model enables determination of which set of data is preferable. Special consideration in this respect is given to the influence of magnesium flouride and lithium flouride additions to the melt.

  13. Factors other than chloride level influencing rate of reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Castel, A.; Arliguie, G. [Paul Sabatier Univ., Toulouse (France); Francois, R. [Institut National Des Sciences Appliques, Toulouse (France)

    2000-07-01

    To evaluate the degree of corrosion a 14 year-old concrete member was completely bared and three meter-long beams were stored in three-point flexion in an aggressive environment by sequences of drying and wetting by a salt fog. Total chloride content was measured at the level of all reinforcements. Despite the small concrete cover of 10 mm at the stirrups and 16 mm for the longitudinal reinforcement, no evidence was found to relate corrosion to chloride content, since a large part of the reinforcement was not affected by corrosion. It was concluded that the steel-concrete interface had a major influence on being able to predict the onset of corrosion in relation to chloride content. Indeed, corrosion damage was only present when the steel-concrete interface was damaged. These results call into question the validity of the chloride threshold as the single determining criterion to forecast corrosion development. It is suggested that the nature of the interface between steel and concrete, which may be randomly distributed along the reinforcements, should also be considered. Experimental evidence shows that steel-concrete interface damage is linked to non-elastic behaviour of bond that occurs at a given level of mechanical loading. Therefore, corrosion damage is best considered as a deterministic phenomenon linked to a bonding damage. 25 refs., 2 tabs., 10 figs.

  14. Alloying influences on low melt temperature SnZn and SnBi solder alloys for electronic interconnections

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guang [Stokes Laboratories, Bernal Institute, University of Limerick (Ireland); Department of Civil Engineering and Materials Science, University of Limerick (Ireland); Wilding, Ian J. [Henkel Ltd, Hemel Hempstead (United Kingdom); Collins, Maurice N., E-mail: Maurice.collins@ul.ie [Stokes Laboratories, Bernal Institute, University of Limerick (Ireland)

    2016-04-25

    Due to its commercial potential and the technological challenges associated with processing, low temperature soldering is a topic gaining widespread interest in both industry and academia in the application space of consumer and “throw away” electronics. This review focuses on the latest metallurgical alloys, tin zinc (Sn–Zn) and tin bismuth (Sn–Bi), for lower temperature processed electronic interconnections. The fundamentals of solder paste production and flux development for these highly surface active metallic powders are introduced. Intermetallic compounds that underpin low temperature solder joint production and reliability are discussed. The influence of alloying on these alloys is described in terms of critical microstructural changes, mechanical properties and reliability. The review concludes with an outlook for next generation electronic interconnect materials. - Highlights: • Review of the latest advances in Sn–Zn and Sn–Bi solder alloys. • Technological developments underpinning low temperature soldering. • Micro alloying influences on next generation interconnect materials.

  15. An Experimental Investigation of Ice-melting and heat transfer rates from submerged warm water jets upward impinging into ice-blocks as analogous for water-filled cavities formed during subglacial eruptions.

    Science.gov (United States)

    Jamshidnia, Hamidreza; Gudmundsson, Magnus Tumi

    2016-11-01

    Rates of energy transfer in water-filled cavities formed under glaciers by geothermal and volcanic activity are investigated by conducting experiments in which hot water jets (10°- 90°C) impinging into an ice block for jet Reynolds numbers in turbulent regime of 10000 -70000. It is found that heat flux is linearly dependent on jet flow temperature. Water jet melts a cavity into an ice block. Cavities had steep to vertical sides with a doming roof. Some of ice blocks used had trapped air bubbles. In these cases that melting of the ice could have led to trapping of air at the top of cavity, partially insulating the roof from hot water jet. The overall heat transfer rate in cavity formation varied with jet temperature from <100 kW m-2 to 900 kW m-2 while melting rates in the vertical direction yield heat transfer rates of 200-1200 kW m-2. Experimental heat transfer rates can be compared to data on subglacial melting observed for ice cauldrons in Iceland. For lowest temperatures the numbers are comparable to those for geothermal water in cool, subglacial water bodies and above subglacial flowpaths of jökulhlaups. Highest experimental rates for 80-90°C jets are 3-10 times less than inferred from observations of recent subglacial eruptions (2000-4000 kW m-2) . This can indicate that single phase liquid water convection alone may not be sufficient to explain the rates seen in recent subglacial eruptions, suggesting that forced 2 or 3 phase convection can be common.

  16. Influence of aluminum on the hydrothermal alteration rate of olivine

    Science.gov (United States)

    Andreani, M.; Daniel, I.; Pollet-Villard, M.

    2013-12-01

    The reactivity of ultramafic rocks under hydrothermal conditions controls chemical fluxes at the interface between the internal and external reservoirs of silicate planets. On Earth, hydration of ultramafic rocks is ubiquitous and operates from deep subduction zones to shallow lithospheric environments where it considerably affects the physical and chemical properties of rocks and can interact with the biosphere. This process also has key emerging societal implications, such as the production of hydrogen as a source of carbon-free energy. To date, the chemical model systems used to reproduce olivine hydrothermal alteration lead to the formation of serpentine with sluggish reaction rates. Although aluminum is common in geological environments and in hydrothermal systems in particular, its role in serpentinization or olivine dissolution has not been investigated under hydrothermal conditions. Nevertheless, abundant Al supply is expected in fluids released from dehydration of metapelites in subduction zones as well as during the hydrothermal alteration of gabbros at mid-ocean ridges. Aluminum was also abundant in primitive environments of both the Earth and Mars, stored in either Al-rich minerals like plagioclase or Al-enriched ultramafic lavas. We have investigated the role of Al on the hydrothermal alteration of olivine in a series of experiments performed in a low-pressure diamond anvil cell while following the reaction progress in situ by optical imaging and by confocal Raman spectroscopy. Experiments were run for 4.5 to 7.5 days with two olivine grains reacted in saline water (0.5 molal NaCl) at 200°C and 300°C, and P=200 MPa. After two days, olivine crystals were fully transformed to an aluminous serpentine, also enriched in iron. The very fast precipitation of serpentine may inhibit magnetite nucleation here. However, this does not rule out an H2 production since serpentines classically incorporate non negligible amount of ferric iron in their structure. The

  17. THE INFLUENCES OF MELT-COMPOUNDING PARAMETERS ON THE TENSILE PROPERTIES OF LOW FILLER LOADING OF UNTREATED-MWCNTs-POLYPROPYLENE (PP NANOCOMPOSITES

    Directory of Open Access Journals (Sweden)

    M.A.MOHD SALLEH

    2008-04-01

    Full Text Available This study is to investigate the effects of addition self synthesised multi-walled carbon nanotubes (MWCNTs, to the final properties of polypropylene (PP matrix nanocomposites. The influences of melt blending parameters were evaluated, where the interrelationship between the temperatures of compounding and roller rotor speed of shearing blade parameter, to the tensile properties of fabricated composites were studied. MWCNT was synthesised in the laboratory scale; by using the floating catalyst chemical vapour deposition (FC-CVD method. Pre-compounding work is begun with de-agglomeration of MWCNT which carried out by combining the ultrasonication and mechanical stirrer means simultaneously. Carbon nanotubes produced was first verified by using SEM and TEM imaging microscopy techniques. It was later integrated with the thermoplastic PP matrix, via melt blending process through internally mixing approach. Very low weight percentage of chemically untreated MWCNT (0, 0.25, 0.50, 0.75 & 1.00 wt. % was added into PP and later was compression moulded to the thin sheet of composites film. Composites were prepared by varying the compounding temperature into three processing temperature namely 165, 175 & 185°C and also into three shearing speed of roller rotor blade, 40, 60 & 80 rpm respectively. Later, it was mechanically tested via tensile testing following the ASTM D-638 standard method. The interrelationship between each parameter of compounding to the mechanical tensile properties was tested. It was shown that, the additional of very low loading of untreated-MWCNT filler content, does give moderate effects on reinforcement to the tensile properties of composite. Different compounding parameter gives significant difference to the pattern of plot which was comparable between each other.

  18. The tacrolimus metabolism rate influences renal function after kidney transplantation.

    Directory of Open Access Journals (Sweden)

    Gerold Thölking

    Full Text Available The effective calcineurin inhibitor (CNI tacrolimus (Tac is an integral part of the standard immunosuppressive regimen after renal transplantation (RTx. However, as a potent CNI it has nephrotoxic potential leading to impaired renal function in some cases. Therefore, it is of high clinical impact to identify factors which can predict who is endangered to develop CNI toxicity. We hypothesized that the Tac metabolism rate expressed as the blood concentration normalized by the dose (C/D ratio is such a simple predictor. Therefore, we analyzed the impact of the C/D ratio on kidney function after RTx. Renal function was analyzed 1, 2, 3, 6, 12 and 24 months after RTx in 248 patients with an immunosuppressive regimen including basiliximab, tacrolimus, mycophenolate mofetil and prednisolone. According to keep the approach simple, patients were split into three C/D groups: fast, intermediate and slow metabolizers. Notably, compared with slow metabolizers fast metabolizers of Tac showed significantly lower estimated glomerular filtration rate (eGFR values at all the time points analyzed. Moreover, fast metabolizers underwent more indication renal biopsies (p = 0.006 which revealed a higher incidence of CNI nephrotoxicity (p = 0.015 and BK nephropathy (p = 0.024 in this group. We herein identified the C/D ratio as an easy calculable risk factor for the development of CNI nephrotoxicity and BK nephropathy after RTx. We propose that the simple C/D ratio should be taken into account early in patient's risk management strategies.

  19. The Influence of As-Built Surface Conditions on Mechanical Properties of Ti-6Al-4V Additively Manufactured by Selective Electron Beam Melting

    Science.gov (United States)

    Sun, Y. Y.; Gulizia, S.; Oh, C. H.; Fraser, D.; Leary, M.; Yang, Y. F.; Qian, M.

    2016-03-01

    Achieving a high surface finish is a major challenge for most current metal additive manufacturing processes. We report the first quantitative study of the influence of as-built surface conditions on the tensile properties of Ti-6Al-4V produced by selective electron beam melting (SEBM) in order to better understand the SEBM process. Tensile ductility was doubled along with noticeable improvements in tensile strengths after surface modification of the SEBM-fabricated Ti-6Al-4V by chemical etching. The fracture surfaces of tensile specimens with different surface conditions were characterised and correlated with the tensile properties obtained. The removal of a 650- μm-thick surface layer by chemical etching was shown to be necessary to eliminate the detrimental influence of surface defects on mechanical properties. The experimental results and analyses underline the necessity to modify the surfaces of SEBM-fabricated components for structural applications, particularly for those components which contain complex internal concave and convex surfaces and channels.

  20. Influence of Molecular Weight of Carriers and Processing Parameters on the Extrudability, Drug Release, and Stability of Fenofibrate Formulations Processed by Hot-Melt Extrusion.

    Science.gov (United States)

    Alsulays, Bader B; Park, Jun-Bom; Alshehri, Sultan M; Morott, Joseph T; Alshahrani, Saad M; Tiwari, Roshan V; Alshetaili, Abdullah S; Majumdar, Soumyajit; Langley, Nigel; Kolter, Karl; Gryczke, Andreas; Repka, Michael A

    2015-10-01

    The objective of this study was to investigate the extrudability, drug release, and stability of fenofibrate (FF) formulations utilizing various hot-melt extrusion processing parameters and polyvinylpyrrolidone (PVP) polymers of various molecular weights. The different PVP grades selected for this study were Kollidon(®) 12 PF (K12), Kollidon(®) 30 (K30), and Kollidon(®) 90 F (K90). FF was extruded with these polymers at three drug loadings (15%, 25%, and 35% w/w). Additionally, for FF combined with each of the successfully extruded PVP grades (K12 and K30), the effects of two levels of processing parameters for screw design, screw speed, and barrel temperature were assessed. It was found that the FF with (K90) was not extrudable up to 35% drug loading. With low drug loading, the polymer viscosity significantly influenced the release of FF. The crystallinity remaining was vital in the highest drug-loaded formulation dissolution profile, and the glass transition temperature of the polymer significantly affected its stability. Modifying the screw configuration resulted in more than 95% post-extrusion drug content of the FF-K30 formulations. In contrast to FF-K30 formulations, FF release and stability with K12 were significantly influenced by the extrusion temperature and screw speed.

  1. Influence of the heart rate on mean circumferential shortening velocity: echocardiographic study of 183 normal subjects.

    Science.gov (United States)

    Mangiarotti, R; Martinotti, R; Monzani, V; Sardella, F; Pierini, A; Pastori, M; Randazzo, A

    1986-01-01

    Echocardiography was used to explore the influence of independent variables (age, body surface area and heart rate) on the mean circumferential shortening velocity (MVCF) in 183 healthy subjects. Multiple stepwise regression analysis shows that heart rate is the only variable of the three just mentioned that influences MVCF. A regression equation is evolved and proposed as an index of MVCF correction for varying heart rates.

  2. Energy model for the Zr-based metallic glass alloy melt with clusters

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An energy model for the melt of bulk metallic glass (BMG) with clusters was estab- lished, the Gibbs free energy and interfacial energy for the Zr-Al-Ni ternary alloy melt with Zr2Ni clusters were calculated, and the effects of the clusters on the Gibbs free energy, interfacial energy and nucleation rate were analyzed. The results showed that the existence of the clusters in the Zr-Al-Ni ternary alloy melt enables the Gibbs free energy to decrease in the composition range where bulk metallic glass forms easily, makes the interfacial energy increase and changes the distribu- tion of the interfacial energy with the alloy composition. Because of the clusters in the melt, the Gibbs free energy of the Zr66Al8Ni26 alloy melt decreases about 0.3-1 kJ/mol and the interfacial energy between the melt and crystal nucleus increases about 0.016 J/m2. The nucleation rate of the undercooled Zr66Al8Ni26 alloy melt de- creases evidently under the influence of the clusters on Gibbs free energy and the interfacial energy, and the maximum of the nucleation rate in the melt with the Zr2Ni clusters is only about 107 mol1s1.

  3. Energy model for the Zr-based metallic glass alloy melt with clusters

    Institute of Scientific and Technical Information of China (English)

    YANG YuanSheng; LI HuiQiang; TONG WenHui

    2007-01-01

    An energy model for the melt of bulk metallic glass (BMG) with clusters was established, the Gibbs free energy and interfacial energy for the Zr-Al-Ni ternary alloy melt with Zr2Ni clusters were calculated, and the effects of the clusters on the Gibbs free energy, interfacial energy and nucleation rate were analyzed. The results showed that the existence of the clusters in the Zr-Al-Ni ternary alloy melt enables the Gibbs free energy to decrease in the composition range where bulk metallic glass forms easily, makes the interfacial energy increase and changes the distribution of the interfacial energy with the alloy composition. Because of the clusters in the melt, the Gibbs free energy of the Zr66Al8Ni26 alloy melt decreases about 0.3-1 kJ/mol and the interfacial energy between the melt and crystal nucleus increases about 0.016 J/m2. The nucleation rate of the undercooled Zr66Al8Ni26 alloy melt decreases evidently under the influence of the clusters on Gibbs free energy and the interfacial energy, and the maximum of the nucleation rate in the melt with the Zr2Ni clusters is only about 107 mol-1·s-1.

  4. The influence of melt convection on dendritic spacing of downward unsteady-state directionally solidified Sn-Pb alloys

    Directory of Open Access Journals (Sweden)

    José Eduardo Spinelli

    2006-03-01

    Full Text Available Microstructures are the strategic link between materials processing and materials behavior. A dendritic structure is the most frequently observed pattern of solidified alloys. The microstructural scales of dendrites, such as primary and secondary arm spacings, control the segregation profiles and the formation of secondary phases within interdendritic regions, determine the properties of cast structures. In this work, the influence of thermosolutal convection on dendrite arm spacings is experimentally examined in the downward vertical unsteady-state directional solidification of Sn-Pb hypoeutectic alloys. The experimental observations are compared not only with the main predictive theoretical models for dendritic spacings but also with experimental results obtained for Sn-Pb alloys solidified vertically upwards. Primary dendritic arm spacings have been affected by the direction of growth, decreasing in conditions of downward vertical solidification when compared with those grown vertically upwards. Further, the unsteady-state lambda1 predictive models did not generate the experimental observations.

  5. Influence of heavy cigarette smoking on heart rate variability and heart rate turbulence parameters

    DEFF Research Database (Denmark)

    Cagirci, Goksel; Cay, Serkan; Karakurt, Ozlem

    2009-01-01

    BACKGROUND: Cigarette smoking increases the risk of cardiovascular events related with several mechanisms. The most suggested mechanism is increased activity of sympathetic nervous system. Heart rate variability (HRV) and heart rate turbulence (HRT) has been shown to be independent and powerful...... predictors of mortality in a specific group of cardiac patients. The goal of this study was to assess the effect of heavy cigarette smoking on cardiac autonomic function using HRV and HRT analyses. METHODS: Heavy cigarette smoking was defined as more than 20 cigarettes smoked per day. Heavy cigarette smokers......, 69 subjects and nonsmokers 74 subjects (control group) were enrolled in this study. HRV and HRT analyses [turbulence onset (TO) and turbulence slope (TS)] were assessed from 24-hour Holter recordings. RESULTS: The values of TO were significantly higher in heavy cigarette smokers than control group...

  6. Eruption style at Kīlauea Volcano in Hawai‘i linked to primary melt composition

    Science.gov (United States)

    Sides. I.R.,; Edmonds, M.; Maclennan, J.; Swanson, Don; Houghton, B.F.

    2014-01-01

    Explosive eruptions at basaltic volcanoes have been linked to gas segregation from magmas at shallow depths in the crust. The composition of primary melts formed at greater depths was thought to have little influence on eruptive style. Ocean island basaltic volcanoes are the product of melting of a geochemically heterogeneous mantle plume and are expected to give rise to heterogeneous primary melts. This range in primary melt composition, particularly with respect to the volatile components, will profoundly influence magma buoyancy, storage and eruption style. Here we analyse the geochemistry of a suite of melt inclusions from 25 historical eruptions at the ocean island volcano of Kīlauea, Hawai‘i, over the past 600 years. We find that more explosive styles of eruption at Kīlauea Volcano are associated statistically with more geochemically enriched primary melts that have higher volatile concentrations. These enriched melts ascend faster and retain their primary nature, undergoing little interaction with the magma reservoir at the volcano’s summit. We conclude that the eruption style and magma-supply rate at Kīlauea are fundamentally linked to the geochemistry of the primary melts formed deep below the volcano. Magmas might therefore be predisposed towards explosivity right at the point of formation in their mantle source region.

  7. Influence of heart rate in nonlinear HRV indices as a sampling rate effect evaluated on supine and standing

    Directory of Open Access Journals (Sweden)

    Juan Bolea

    2016-11-01

    Full Text Available The purpose of this study is to characterize and attenuate the influence of mean heart rate (HR on nonlinear heart rate variability (HRV indices (correlation dimension, sample and approximate entropy as a consequence of being the HR the intrinsic sampling rate of HRV signal. This influence can notably alter nonlinear HRV indices and lead to biased information regarding autonomic nervous system (ANS modulation.First, a simulation study was carried out to characterize the dependence of nonlinear HRV indices on HR assuming similar ANS modulation. Second, two HR-correction approaches were proposed: one based on regression formulas and another one based on interpolating RR time series. Finally, standard and HR-corrected HRV indices were studied in a body position change database.The simulation study showed the HR-dependence of non-linear indices as a sampling rate effect, as well as the ability of the proposed HR-corrections to attenuate mean HR influence. Analysis in a body position changes database shows that correlation dimension was reduced around 21% in median values in standing with respect to supine position (p < 0.05, concomitant with a 28% increase in mean HR (p < 0.05. After HR-correction, correlation dimension decreased around 18% in standing with respect to supine position, being the decrease still significant. Sample and approximate entropy showed similar trends.HR-corrected nonlinear HRV indices could represent an improvement in their applicability as markers of ANS modulation when mean HR changes.

  8. Influences of glacial melt and permafrost thaw on the age of dissolved organic carbon in the Yukon River basin

    Science.gov (United States)

    Aiken, George R.; Spencer, Robert G.M.; Striegl, Rob; Schuster, Paul F.; Raymond, Peter A.

    2016-01-01

    Responses of near-surface permafrost and glacial ice to climate change are of particular significance for understanding long-term effects on global carbon cycling and carbon export by high-latitude northern rivers. Here we report Δ14C-dissolved organic carbon (DOC) values and dissolved organic matter optical data for the Yukon River, 15 tributaries of the Yukon River, glacial meltwater, and groundwater and soil water end-member sources draining to the Yukon River, with the goal of assessing mobilization of aged DOC within the watershed. Ancient DOC was associated with glacial meltwater and groundwater sources. In contrast, DOC from watersheds dominated by peat soils and underlain by permafrost was typically enriched in Δ14C indicating that degradation of ancient carbon stores is currently not occurring at large enough scales to quantitatively influence bulk DOC exports from those landscapes. On an annual basis, DOC exported was predominantly modern during the spring period throughout the Yukon River basin and became older through summer-fall and winter periods, suggesting that contributions of older DOC from soils, glacial meltwaters, and groundwater are significant during these months. Our data indicate that rapidly receding glaciers and increasing groundwater inputs will likely result in greater contributions of older DOC in the Yukon River and its tributaries in coming decades.

  9. Fault rheology beyond frictional melting.

    Science.gov (United States)

    Lavallée, Yan; Hirose, Takehiro; Kendrick, Jackie E; Hess, Kai-Uwe; Dingwell, Donald B

    2015-07-28

    During earthquakes, comminution and frictional heating both contribute to the dissipation of stored energy. With sufficient dissipative heating, melting processes can ensue, yielding the production of frictional melts or "pseudotachylytes." It is commonly assumed that the Newtonian viscosities of such melts control subsequent fault slip resistance. Rock melts, however, are viscoelastic bodies, and, at high strain rates, they exhibit evidence of a glass transition. Here, we present the results of high-velocity friction experiments on a well-characterized melt that demonstrate how slip in melt-bearing faults can be governed by brittle fragmentation phenomena encountered at the glass transition. Slip analysis using models that incorporate viscoelastic responses indicates that even in the presence of melt, slip persists in the solid state until sufficient heat is generated to reduce the viscosity and allow remobilization in the liquid state. Where a rock is present next to the melt, we note that wear of the crystalline wall rock by liquid fragmentation and agglutination also contributes to the brittle component of these experimentally generated pseudotachylytes. We conclude that in the case of pseudotachylyte generation during an earthquake, slip even beyond the onset of frictional melting is not controlled merely by viscosity but rather by an interplay of viscoelastic forces around the glass transition, which involves a response in the brittle/solid regime of these rock melts. We warn of the inadequacy of simple Newtonian viscous analyses and call for the application of more realistic rheological interpretation of pseudotachylyte-bearing fault systems in the evaluation and prediction of their slip dynamics.

  10. The Influence of Process Parameters on the Surface Roughness of a 3D-Printed Co–Cr Dental Alloy Produced via Selective Laser Melting

    Directory of Open Access Journals (Sweden)

    Min-Ho Hong

    2016-12-01

    Full Text Available Selective laser melting (SLM, used to fabricate metallic objects with high geometrical complexity, is currently of increasing interest to the fields of medicine and dentistry. SLM-fabricated products should have highly smooth surfaces to minimize the use of post-processing procedures such as finishing and polishing. This study investigated the effect of various laser process parameters (laser power, scan rate, and scan-line spacing on the surface roughness of a Co–Cr dental alloy that was three-dimensionally (3D constructed via SLM. Initially, a single-line formation test was used to determine the optimal laser power (200 W and scan rate (128.6 mm/s that resulted in beads with an optimal profile. During subsequent multi-layer formation tests, the 3D Co–Cr body with the smoothest surface was produced using a scan-line spacing of 100 μm. The findings of this study show that laser process parameters have crucial effects on the surface quality of SLM-fabricated Co–Cr dental alloys.

  11. Influence of live mass, rate of passage and site of digestion on ...

    African Journals Online (AJOL)

    geabsorbeer. 1 Part of a Ph.D.(Agric.) ... intensive production of ostriches to produce meat, skins and ..... 1984). This process exposes a larger surface area for enzymic ..... Particulate rumen turnover rate measurement as influenced by density.

  12. Influence of Melt Superheat, Sr Modifier, and Al-5Ti-1B Grain Refiner on Microstructural Evolution of Secondary Al-Si-Cu Alloys

    Science.gov (United States)

    Rakhmonov, Jovid; Timelli, Giulio; Bonollo, Franco

    2016-11-01

    The role of impurity elements and melt superheat on the efficiency of Sr modification, grain refinement with Al-Ti-B and the precipitation behavior of intermetallic phases in a secondary Al-7Si-3Cu-0.3Mg alloy were investigated. Metallographic and thermal analysis techniques were used to quantitatively examine the macro- and microstructural changes occurring with modifier and grain refiner additions at various pouring temperatures. The results indicate how the Sr modification and grain refinement with Al-Ti-B can be effective enough despite the presence of impurity elements in the material and the variation of pouring temperature. A slight poisonous effect of impurities, in particular, Zr and V, in the grain refinement efficiency can be eventually induced due to their action in promoting the formation of primary AlSiTi compounds. Moreover, grain refiner addition exerted a pronounced influence on the precipitation sequence of Fe-rich phases. The TiB2 particles appeared to promote the formation of Al5FeSi during solidification by acting as a favorable nucleation site.

  13. Pavement Snow Melting

    Energy Technology Data Exchange (ETDEWEB)

    Lund, John W.

    2005-01-01

    The design of pavement snow melting systems is presented based on criteria established by ASHRAE. The heating requirements depends on rate of snow fall, air temperature, relative humidity and wind velocity. Piping materials are either metal or plastic, however, due to corrosion problems, cross-linked polyethylene pipe is now generally used instead of iron. Geothermal energy is supplied to systems through the use of heat pipes, directly from circulating pipes, through a heat exchanger or by allowing water to flow directly over the pavement, by using solar thermal storage. Examples of systems in New Jersey, Wyoming, Virginia, Japan, Argentina, Switzerland and Oregon are presented. Key words: pavement snow melting, geothermal heating, heat pipes, solar storage, Wyoming, Virginia, Japan, Argentina, Klamath Falls.

  14. The influence of cooling, crystallisation and re-melting on the interpretation of geodetic signals in volcanic systems

    Science.gov (United States)

    Caricchi, Luca; Biggs, Juliet; Annen, Catherine; Ebmeier, Susanna

    2014-02-01

    Deformation of volcanic edifices is typically attributed to the movement of magma within the volcanic plumbing system, but a wide range of magmatic processes are capable of producing significant volume variations and may also produce deformation. In order to understand the evolution of magmatic systems prior to eruption and correctly interpret monitoring signals, it is necessary to quantify the patterns and timescales of surface deformation that processes such as crystallisation, degassing and expansion of the hydrothermal system can produce. We show how the combination of petrology and thermal modelling can be applied to geodetic observations to identify the processes occurring in a magmatic reservoir during volcanic unrest. Thermal modelling and petrology were used to determine the timescales and volumetric variations associated with cooling, crystallisation and gas exsolution. These calculations can be performed rapidly and highlight the most likely processes responsible for the variation of a set of monitoring parameters. We then consider the magnitude and timescales of deformation produced by other processes occurring within the vicinity of an active magma system. We apply these models to a time series of geodetic data spanning the period between the 1997 and 2008 eruptions of Okmok volcano, Aleutians, examining scenarios involving crystallisation, degassing and remelting of the crystallising shallow magmatic body and including a viscoelastic shell or hydrothermal system. The geodetic observations are consistent with the injection of a water-saturated basalt, followed by minor crystallisation and degassing. Other scenarios are not compatible either with the magnitude or rate of the deformation signals.

  15. The influence of alkaline earth metal equilibria on the rheological, melting and textural properties of Cheddar cheese.

    Science.gov (United States)

    Cooke, Darren R; McSweeney, Paul L H

    2013-11-01

    The total calcium content of cheese, along with changes in the equilibrium between soluble and casein (CN)-bound calcium during ripening can have a major impact on its rheological, functional and textural properties; however, little is known about the effect of other alkaline earth metals. NaCl was partially substituted with MgCl2 or SrCl2 (8·7 and 11·4 g/kg curd, respectively) at the salting stage of cheesemaking to study their effects on cheese. Three cheeses were produced: Mg supplemented (+Mg), Sr supplemented (+Sr) and a control Cheddar cheese. Ca, Mg and Sr contents of cheese and expressible serum obtained therefrom were determined by atomic absorption spectroscopy. Addition of Mg2+ or Sr2+ had no effect on % moisture, protein, fat and extent of proteolysis. A proportion of the added Mg2+ and Sr2+ became CN-bound. The level of CN-bound Mg was higher in the +Mg cheese than the control throughout ripening. The level of CN-bound Ca and Mg decreased during ripening in all cheeses, as did % CN-bound Sr in the +Sr cheese. The presence of Sr2+ increased % CN-bound Ca and Mg at a number of ripening times. Adding Mg2+ had no effect on % CN-bound Ca. The +Sr cheese exhibited a higher G' at 70 °C and a lower LTmax than the control and +Mg cheeses throughout ripening. The +Sr cheese had significantly lower meltability compared with the control and +Mg cheeses after 2 months of ripening. Hardness values of the +Sr cheese were higher at week 2 than the +Mg and control cheeses. Addition of Mg2+ did not influence the physical properties of cheese. Supplementing cheese with Sr appeared to have effects analogous to those previously reported for increasing Ca content. Sr2+ may form and/or modify nanocluster crosslinks causing an increase in the strength of the para-casein matrix.

  16. The influence of pretreatment on cure rates of Helicobacter pylori eradication.

    NARCIS (Netherlands)

    Janssen, M.J.R.; Laheij, R.J.F.; Jansen, J.B.M.J.; Boer, W.A. de

    2004-01-01

    BACKGROUND: Many patients treated for H. pylori infection have been taking a proton pump inhibitor beforehand. There is conflicting evidence whether pretreatment influences the efficacy of H. pylori eradication. The aim of this study was to investigate the influence of pretreatment on cure rates of

  17. Determination of geometrical factors in Layerwise Laser Melting using optical process monitoring

    Science.gov (United States)

    Craeghs, Tom; Clijsters, Stijn; Yasa, Evren; Bechmann, Florian; Berumen, Sebastian; Kruth, Jean-Pierre

    2011-12-01

    Layerwise Laser Melting (LLM) is a layerwise production technique enabling the production of complex metallic parts. In the process a thin layer of powder is first deposited on a base plate. With the energy of a scanning laser beam this layer is melted at selected places, according to a predefined scanning pattern. After scanning, a new layer of powder is deposited on top of the previous layer and selectively melted. This sequence of depositing and scanning is repeated until the complete part is built. The local geometry surrounding the melt pool has a large influence on the processing behavior. For process control issues, this influence must be known and quantified, in order to determine a priori optimal processing conditions and to interpret measured melt pool radiation. In order to study the melt pool behavior, optical process monitoring of LLM has been applied using a high speed near-infrared CMOS camera and a large area silicon photodiode sensor. Data processing rates up to 10 kHz and real-time process monitoring are achieved using image and signal processing on a Field Programmable Gate Array (FPGA). Several case studies will be presented showing that the geometric influencing factors can be studied and quantified by analyzing the melt pool sensor output.

  18. Anodic oxidation of oxytetracycline: Influence of the experimental conditions on the degradation rate and mechanism

    Directory of Open Access Journals (Sweden)

    Annabel Fernandes

    2014-12-01

    Full Text Available The anodic oxidation of oxytetracycline was performed with success using as anode a boron-doped diamond electrode. The experiments were conducted in batch mode, using two different electrochemical cells: an up-flow cell, with recirculation, that was used to evaluate the influence of recirculation flow rate; and a stirred cell, used to determine the influence of the applied current density. Besides oxytetracyclin electrodegradation rate and mineralization extent, oxidation by-products were also assessed. Both the flow rate and the applied current density have shown positive influence on the oxytetracycline oxidation rate. On the other hand, the mineralization degree presented the highest values at the lowest flow rate and the lowest current density tested. The main oxidation by-products detected were oxalic, oxamic and maleic acids.

  19. Influence of nitrogen rate on the efficacy of herbicides with different modes of action

    DEFF Research Database (Denmark)

    Sønderskov, Mette; Swanton, C. J.; Kudsk, Per Nielsen

    2012-01-01

    -methyl. An increased susceptibility at high nitrogen rate was also observed for Anagallis arvensis, but in contrast to T. inodorum, growth of unsprayed A. arvensis was unaffected by nitrogen rate. Growth of unsprayed Chenopodium album was also promoted by nitrogen supply. However, no influence of nitrogen rate...... affected herbicide efficacy for some but not all combinations of weed species and herbicide. Decreased herbicide efficacy was only observed at very low nitrogen rates. The results suggest that the effect of nitrogen rates on herbicide efficacy will be marginal in intensive farming systems with high......Outdoor pot experiments and field experiments were conducted to examine the influence of nitrogen rate on herbicide efficacy. Growth of unsprayed Tripleurospermum inodorum increased with increasing nitrogen rate in pot experiments; increasing nitrogen also increased the susceptibility to tribenuron...

  20. Grain-scale alignment of melt in sheared partially molten rocks: implications for viscous anisotropy

    Science.gov (United States)

    Pec, Matej; Quintanilla-Terminel, Alejandra; Holtzman, Benjamin; Zimmerman, Mark; Kohlstedt, David

    2016-04-01

    Presence of melt significantly influences rheological properties of partially molten rocks by providing fast diffusional pathways. Under stress, melt aligns at the grain scale and this alignment induces viscous anisotropy in the deforming aggregate. One of the consequences of viscous anisotropy is melt segregation into melt-rich sheets oriented at low angle to the shear plane on much larger scales than the grain scale. The magnitude and orientation of viscous anisotropy with respect to the applied stress are important parameters for constitutive models (Takei and Holtzman 2009) that must be constrained by experimental studies. In this contribution, we analyze the shape preferred orientation (SPO) of individual grain-scale melt pockets in deformed partially molten mantle rocks. The starting materials were obtained by isostatically hot-pressing olivine + basalt and olivine + chromite + basalt powders. These partially molten rocks were deformed in general shear or torsion at a confining pressure, Pc = 300 MPa, temperature, T = 1200° - 1250° C, and strain rates of 10-3 - 10-5 s-1to finite shear strains, γ, of 0.5 - 5. After the experiment, high resolution backscattered electron images were obtained using a SEM equipped with a field emission gun. Individual melt pockets were segmented and their SPO analyzed using the paror and surfor methods and Fourier transforms (Heilbronner and Barret 2014). Melt segregation into melt-rich sheets inclined at 15° -20° antithetic with respect to the shear plane occurs in three-phase system (olivine + chromite + basalt) and in two-phase systems (olivine + basalt) twisted to high strain. The SPO of individual melt pockets within the melt-rich bands is moderately strong (b/a ≈ 0.8) and is always steeper (20° -40°) than the average melt-rich band orientation. In the two-phase system (olivine + basalt) sheared to lower strains, no distinct melt-rich sheets are observed. Individual grain-scale melt pockets are oriented at 45° -55

  1. Influence of mRNA decay rates on the computational prediction of transcription rate profiles from gene expression profiles

    Indian Academy of Sciences (India)

    Chi-Fang Chin; Arthur Chun-Chieh Shih; Kuo-Chin Fan

    2007-12-01

    The abundance of an mRNA species depends not only on the transcription rate at which it is produced, but also on its decay rate, which determines how quickly it is degraded. Both transcription rate and decay rate are important factors in regulating gene expression. With the advance of the age of genomics, there are a considerable number of gene expression datasets, in which the expression profiles of tens of thousands of genes are often non-uniformly sampled. Recently, numerous studies have proposed to infer the regulatory networks from expression profiles. Nevertheless, how mRNA decay rates affect the computational prediction of transcription rate profiles from expression profiles has not been well studied. To understand the influences, we present a systematic method based on a gene dynamic regulation model by taking mRNA decay rates, expression profiles and transcription profiles into account. Generally speaking, an expression profile can be regarded as a representation of a biological condition. The rationale behind the concept is that the biological condition is reflected in the changing of gene expression profile. Basically, the biological condition is either associated to the cell cycle or associated to the environmental stresses. The expression profiles of genes that belong to the former, so-called cell cycle data, are characterized by periodicity, whereas the expression profiles of genes that belong to the latter, so-called condition-specific data, are characterized by a steep change after a specific time without periodicity. In this paper, we examine the systematic method on the simulated expression data as well as the real expression data including yeast cell cycle data and condition-specific data (glucose-limitation data). The results indicate that mRNA decay rates do not significantly influence the computational prediction of transcription-rate profiles for cell cycle data. On the contrary, the magnitudes and shapes of transcription-rate profiles for

  2. Temperature-induced anomalous structural changes of Al-12wt.%Sn-4wt.%Si melt and its influence on as-cast structure

    Directory of Open Access Journals (Sweden)

    Wang Zhiming

    2010-05-01

    Full Text Available The temperature dependence of the viscosity of liquid Al-12wt.%Sn-4wt.%Si was studied with a high-temperature viscosity apparatus. Anomalous changes of viscosity of the melt were found at 1,103 K and 968 K in the cooling process, which indicates anomalous structural changes of the melt. It is calculated that the anomalous structural change is associated with an abrupt decrease of atomic clusters’ size and activation energy in the melt. According to the temperature of the anomalous structural changes, melt heat treatment process (quenching from superheat to pouring temperature was performed on Al-12wt.%Sn-4wt.%Si melt prior to pouring, aimed to keep the small atomic clusters from higher temperature to lower pouring temperature. The results suggest that relatively small atomic clusters at the pouring temperature in the melt could generate a deep under-cooling of nucleation in the subsequent solidification process, and refine the as-cast structure. After being quenched from superheating to pouring temperature, the relatively small atomic clusters, especially the Si-Si clusters in the melt will grow to equilibrium state (relatively big atomic clusters with holding time, resulting in the prominent coarsening of the Si morphology in the as-cast structure.

  3. Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and micro-structure of the bronze CuAl10Ni5Fe4

    Directory of Open Access Journals (Sweden)

    B. Pisarek

    2010-04-01

    Full Text Available Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the quantity the slag rafining - covering Unitop BA-1 (0÷1,5% on the effectiveness of the protection of liquid bronze before the oxygenation, the quantity of the preliminary alloy - in-oculant AlBe5 (0÷1,0% on the effective compensation melting loss of aluminum and time of isothermal holding on the effect of the in-oculation of the bronze and the comparison of the effectiveness of the inoculation of the bronze in furnace and in the form. Introduced investigations resulted from the study of the new grades of the Cu-Al-Fe-Ni bronze with additions singly or simultaneously Si, Cr, Mo and/or W, to melting which necessary it is for high temperature and comparatively long time isothermal holding indispensable to the occur of the process of diffusive dissolving the high-melting of the bronze components. High temperature and lengthening the time of isothermal holding the liquid bronze in casting furnace the melting loss of Al influences the growth. Addition the slag of covering-refining Unitop BA-1 in the quantity 1,5% the bronze protects before the melting loss of aluminum by the time of isothermal holding in the temperature 1300°C about 15 minutes. Addition of the preliminary alloy AlBe5 in the quantity 0,6% it assures the effective compensation of the aluminum which melting loss undergoes for the studied parameters of the melting. The effect of the inoculation of the bronze together with diminishes the preliminary alloy AlBe5 with lengthening the time of isothermal hold-ing. Because of this, use of the method of introducing the preliminary alloy it is seems good solution on the inoculation of aluminum bronzes directly to form, unsensitive on the time of isothermal holding the bronze.

  4. Factors Influencing Middle and High Schools' Active Parental Consent Return Rates

    Science.gov (United States)

    Ji, Peter Y.; Pokorny, Steven B.; Jason, Leonard A.

    2004-01-01

    The authors examined factors influencing the return rates for attempting to collect active parental consent forms from 21,123 students in the 7th through 10th grades in 41 middle and high schools. Overall return rates from middle schools were higher than from high schools. Schools that offered high levels of staff support for collecting consent…

  5. Influence of formulation and process parameters on the release characteristics of ethylcellulose sustained-release mini-matrices produced by hot-melt extrusion.

    Science.gov (United States)

    Verhoeven, E; De Beer, T R M; Van den Mooter, G; Remon, J P; Vervaet, C

    2008-05-01

    Mini-matrices (multiple unit dosage form) with release-sustaining properties were developed by hot-melt extrusion (cylindrical die: 3mm) using metoprolol tartrate as model drug and ethylcellulose as sustained-release agent. Dibutyl sebacate was selected as plasticizer and its concentration was optimized to 50% (w/w) of the ethylcellulose concentration. Xanthan gum, a hydrophilic polymer, was added to the formulation to increase drug release. Changing the xanthan gum concentration modified the in vitro drug release: increasing xanthan gum concentrations (1%, 2.5%, 5%, 10% and 20%, w/w) yielded a faster drug release. Zero-order drug release was obtained at 5% (w/w) xanthan gum. Using kneading paddles, smooth extrudates were obtained when processed at 60 degrees C. At least one mixing zone was required to obtain smooth and homogeneous extrudates. The mixing efficacy and drug release were not affected by the number of mixing zones or their position along the extruder barrel. Raman analysis revealed that metoprolol tartrate was homogeneously distributed in the mini-matrices, independent of screw design and processing conditions. Simultaneously changing the powder feed rate (6-25-50 g/min) and screw speed (30-100-200 rpm) did not alter extrudate quality or dissolution properties.

  6. Simulation of ultrasound influence on melt convection for the growth of Ga(x)In(1-x)Sb and Si single crystals by the Czochralski method.

    Science.gov (United States)

    Kozhemyakin, G N; Nemets, L V; Bulankina, A A

    2014-12-01

    The flow simulation for GaxIn1-xSb and Si melts was conducted for quasi-steady conditions. The maximum velocity was under the solid-liquid interface near periphery of the crystals. An introduction of ultrasound into the liquid formed a standing wave channel under the solid-liquid interface, which acted on melt particles. The calculations of convective and ultrasonic forces acting on the particles in the melt showed that the ultrasonic force is much higher than the convective force. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Influence of electron screening on electron capture rate under high density of stellar interior

    Institute of Scientific and Technical Information of China (English)

    罗志全; 彭秋和

    1996-01-01

    The influence of electron screening on electron capture rate in strong screening is investigated, in which the Gamow-Teller resonance transition is considered and the matrix elements for the resonance transition are calculated on the basis of a shell model. The effect of electron screening on electron capture by 56Co is discussed. It is shown that the screening decreases evidently the capture rates in lower temperature and higher density. The effect of electron screening on other nuclear capture rates is estimated. The conclusion derived may influence the research for late stellar evolution and supernova explosion.

  8. Influence of slow disintegrating fertilizer rates on quality of gazania (Gazania rigens L. seedlings

    Directory of Open Access Journals (Sweden)

    Vujošević Ana

    2007-01-01

    Full Text Available The work has examined the influence of slow disintegrating fertilizer rates of Scotts (Osmocote Exact formulation 15:9:9:MgO + Me on quality of Gazania rigens L. seedlings. The seedlings of Gazania rigens L. was produced in polystyrene containers (speedling system and polypropylene pots (pot system. During the production of seedlings the fertilizer has been applied in rates (0, 1, 2, 3, and 4g/l. The results show that the fertilizer rate of substrata 4g/l influences the qualitative properties of Gazania rigens L. seedlings.

  9. Influence of Compacting Rate on the Properties of Compressed Earth Blocks

    Directory of Open Access Journals (Sweden)

    Humphrey Danso

    2016-01-01

    Full Text Available Compaction of blocks contributes significantly to the strength properties of compressed earth blocks. This paper investigates the influence of compacting rates on the properties of compressed earth blocks. Experiments were conducted to determine the density, compressive strength, splitting tensile strength, and erosion properties of compressed earth blocks produced with different rates of compacting speed. The study concludes that although the low rate of compaction achieved slightly better performance characteristics, there is no statistically significant difference between the soil blocks produced with low compacting rate and high compacting rate. The study demonstrates that there is not much influence on the properties of compressed earth blocks produced with low and high compacting rates. It was further found that there are strong linear correlations between the compressive strength test and density, and density and the erosion. However, a weak linear correlation was found between tensile strength and compressive strength, and tensile strength and density.

  10. Preparation of sustained release matrix pellets by melt agglomeration in the fluidized bed: influence of formulation variables and modelling of agglomerate growth.

    Science.gov (United States)

    Pauli-Bruns, Anette; Knop, Klaus; Lippold, Bernhard C

    2010-03-01

    The one-step preparation of sustained release matrix pellets, using a melting procedure in a fluidized bed apparatus, was tested in a 2(3) full factorial design of experiments, using microcrystalline wax as lipophilic binder, theophylline as model drug and talc as additional matrix forming agent. The three influence parameters were (A) size of binder particles, (B) fraction of theophylline in solid particles and (C) fraction of microcrystalline wax in formulation. The response variables were agglomerate size and size distribution, dissolution time, agglomerate crush resistance, sphericity, yield and porosity. Nearly spherical pellets comprising a smooth, closed surface could be obtained with the used method, exhibiting the hollow core typical for the immersion and layering mechanism. The reproducibility was very good concerning all responses. The size of agglomerates is proportional to the size of the binder particles, which serve as cores for pellet formation in the molten state in the fluidized bed. Additionally, the agglomerate size is influenced by the volume of the solid particles in relation to the binder particles, with more solid particles leading to larger agglomerates and vice versa. Dissolution times vary in a very wide range, resulting from the interplay between amount of drug in relation to the meltable matrix substance microcrystalline wax and the non-meltable matrix substance talc. The change of binder particle size does not lead to a structural change of the matrix; both dissolution times and porosity are not significantly altered. Agglomerate crush resistance is low due to the hollow core of the pellets. However, it is significantly increased if the volume fraction of microcrystalline wax in the matrix is high, which means that the matrix is mechanically better stabilized. A theoretical model has been established to quantitatively explain agglomerate growth and very good accordance of the full particle size distributions between predicted and

  11. The influence of national leader change on corruption and sovereign rating

    OpenAIRE

    Kuei-Yuan Wang; Sheng-Min Tu

    2014-01-01

    Corruption is a critical social and ethical problem that can impede the economic growth of a country or even ruin a country. In addition, the importance of the sovereign rating of a country cannot be underestimated. A change in the sovereign rating of a country can affect its borrowing capacity. Using members of the United Nations from 1995 to 2012 as the research sample, this study investigated the influence of national leader change on corruption and sovereign rating by analyzing one year a...

  12. Research of Heating Rates Influence on Layer Coal Gasification of Krasnogorsky And Borodinsky Coal Deposit

    Directory of Open Access Journals (Sweden)

    Jankovskiy Stanislav

    2015-01-01

    Full Text Available Experimental research of heating rate influence on coal samples gasification process of Krasnogorsky and Borodinsky coal deposit ranks A and 2B was done to define optimal heating mode in high intensification of dispersal of inflammable gases conditions. Abundance ratio of carbon monoxide and nitrogen monoxide, water vapor, carbon dioxide at four values of heating rate within the range of 5 to 30 K/min. with further definition of optimal heating rate of coals was stated.

  13. Influences of rare earth element Ce-doping and melt-spinning on microstructure and magnetostriction of Fe{sub 83}Ga{sub 17} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Zhanquan, E-mail: ndyzq@126.com [School of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot 010018 (China); Tian, Xiao, E-mail: nsdtx@126.com [Key Laboratory for Physics and Chemistry of Functional Materials, School of Physics and Electronic Information, Inner Mongolia Normal University, Hohhot 010022 (China); Jiang, Liping; Hao, Hongbo; Zhang, Guangrui; Wu, Shuangxia; Zhao, Zengqi [Baotou Research Institute of Rare Earths, Baotou 014030 (China); Gerile, Naren [Key Laboratory for Physics and Chemistry of Functional Materials, School of Physics and Electronic Information, Inner Mongolia Normal University, Hohhot 010022 (China)

    2015-07-15

    Highlights: • The CeGa{sub 2} phase existing in the Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy is found for the first time. • The (100) orientation of alloy become stronger after Ce doping into the Fe-Ga alloy. • The melt-spinning leads to the formation of asymmetrical DO{sub 3} phase. • The enhanced magnetostriction is credited with new phase and preferred orientation. • The Ce-doping and melt-spinning are beneficial to the improvement of magnetostriction. - Abstract: In order to improve magnetostriction of the polycrystalline Fe-Ga alloy, the rare earth element Ce was firstly doped into Fe{sub 83}Ga{sub 17} and the melt-spinning method was subsequently applied. The as-cast Fe{sub 83}Ga{sub 17} and Ce-doped Fe{sub 83}Ga{sub 17} alloys were prepared by arc melting. Then the as-cast Ce-doped Fe{sub 83}Ga{sub 17} alloy was melt-spun by the melt-spinning technique. The microstructures and magnetostrictions of all these three alloys were investigated by X-ray diffractometer (XRD), scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS), differential scanning calorimeter (DSC) and magnetostriction measurements. The results indicated that the CeGa{sub 2} phase and asymmetrical DO{sub 3} phase are formed caused by Ce-doping and melt-spinning, respectively. The magnetostrictions of three alloys are ranked in sequence the melt-spun Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy > as-cast Fe{sub 83}Ga{sub 17}Ce{sub 0.8} alloy > as-cast Fe{sub 83}Ga{sub 17} alloy. The enhanced magnetostriction is attributed to the fact that the formation of new phases and the preferred orientation along (100) direction.

  14. The influence of thoron on measurement results of radon exhalation rate

    CERN Document Server

    Xiao De Tao; Ling Qiu; Leung, J K C

    2002-01-01

    Because of thoron exhalation, the measurement results of radon exhalation rate using a local still method is usually larger than the true value of radon flux rate of the monitored material surface. The influence of sup 2 sup 1 sup 6 Po(ThA) on radon exhalation rate can be eliminated for sensitive radon monitors. Theoretical evaluations of the influence of sup 2 sup 1 sup 2 Bi(ThC) and sup 2 sup 1 sup 2 Po(ThC')on radon exhalation rate are carried out in a sampler with diameter of 188 mm, and height of 125 mm, and supplied electrostatic field inside (generated by high voltage and electret) under following conditions: the sampling time are 1, 2, 3 h, respectively, thoron exhalation rate is 100 times of radon's. The calculation results indicate that the measurement results of radon flux rate are possibly 35.5% larger than true value due to the influence of thoron for fast and multifunctional radon monitors with electret, high voltage, respectively and using CR-39 SSNTD as detector, but this influence is negligib...

  15. Origin of impact melt rocks in the Bununu howardite

    Science.gov (United States)

    Klein, L. C.; Hewins, R. H.

    1979-01-01

    The Bununu howardite is a polymict regolith breccia which contains impact melt that is largely restricted to a 1-cm thick intrusion containing residual glass. As in Malvern, the melt rock contains melt with meteoritic Ni-Co contents. The cooling rate, interpreted for forming glass from this composition, is a few tenths of a degree per minute. The intrusive melts rock, which is a feature unique to Bununu, may indicate that Bununu was consolidated at the time of impact melting.

  16. Multiple Melting Endotherms of Syndiotactic Polystyrene in β Crystalline Form

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A series of syndiotactic polystyrene (SPS) samples in β crystalline form were prepared by cooling from the melt at various cooling rates. The effects of cooling rate from the melt, and DSC heating rate on the multiple melting behaviors of β crystals were investigated by differential scanning calorimetry (DSC) and modulated differential scanning calorimetry (MDSC), from which the nature of the multiple melting behavior was ascribed to the occurring of a recrystallization process.

  17. Primary crustal melt compositions: Insights into the controls, mechanisms and timing of generation from kinetics experiments and melt inclusions

    Science.gov (United States)

    Acosta-Vigil, Antonio; London, David; Morgan, George B.; Cesare, Bernardo; Buick, Ian; Hermann, Jörg; Bartoli, Omar

    2017-08-01

    We explore the controls, mechanisms and timing of generation of primary melts and their compositions, and show that the novel studies of melt inclusions in migmatites can provide important insights into the processes of crustal anatexis of a particular rock. Partial melting in the source region of granites is dependent on five main processes: (i) supply of heat; (ii) mineral-melt interface reactions associated with the detachment and supply of mineral components to the melt, (iii) diffusion in the melt, (iv) diffusion in minerals, and (v) recrystallization of minerals. As the kinetics of these several processes vary over several orders of magnitude, it is essential to evaluate in Nature which of these processes control the rate of melting, the composition of melts, and the extent to which residue-melt chemical equilibrium is attained under different circumstances. To shed light on these issues, we combine data from experimental and melt inclusion studies. First, data from an extensive experimental program on the kinetics of melting of crustal protoliths and diffusion in granite melt are used to set up the necessary framework that describes how primary melt compositions are established during crustal anatexis. Then, we use this reference frame and compare compositional trends from experiments with the composition of melt inclusions analyzed in particular migmatites. We show that, for the case of El Hoyazo anatectic enclaves in lavas, the composition of glassy melt inclusions provides important information on the nature and mechanisms of anatexis during the prograde suprasolidus history of these rocks, including melting temperatures and reactions, and extent of melt interconnection, melt homogenization and melt-residue equilibrium. Compositional trends in several of the rehomogenized melt inclusions in garnet from migmatites/granulites in anatectic terranes are consistent with diffusion in melt-controlled melting, though trace element compositions of melt inclusions

  18. Continuous manufacturing of solid lipid nanoparticles by hot melt extrusion.

    Science.gov (United States)

    Patil, Hemlata; Kulkarni, Vijay; Majumdar, Soumyajit; Repka, Michael A

    2014-08-25

    Solid lipid nanoparticles (SLN) can either be produced by hot homogenization of melted lipids at higher temperatures or by a cold homogenization process. This paper proposes and demonstrates the formulation of SLN for pharmaceutical applications by combining two processes: hot melt extrusion (HME) technology for melt-emulsification and high-pressure homogenization (HPH) for size reduction. This work aimed at developing continuous and scalable processes for SLN by mixing a lipid and aqueous phase containing an emulsifier in the extruder barrel at temperatures above the melting point of the lipid and further reducing the particle size of emulsion by HPH linked to HME in a sequence. The developed novel platform demonstrated better process control and size reduction compared to the conventional process of hot homogenization (batch process). Varying the process parameters enabled the production of SLN below 200 nm (for 60 mg/ml lipid solution at a flow rate of 100ml/min). Among the several process parameters investigated, the lipid concentration, residence time and screw design played major roles in influencing the size of the SLN. This new process demonstrates the potential use of hot melt extrusion technology for continuous and large-scale production of SLN.

  19. Quench Rate Studies of Aluminum Coordination and Oxygen Speciation in Calcium Aluminosilicate Glasses: Implications for Temperature Effects on the Structure of Aluminosilicate Melts

    Science.gov (United States)

    Dubinsky, E. V.; Stebbins, J. F.

    2006-12-01

    The atomic-scale structure of aluminosilicate glasses and melts is subject to temperature-induced rearrangement, which in turn controls variations in measurable thermodynamic properties. In order to investigate the effect of temperature on the structure of calcium aluminosilicate melts, we have used Al-27 MAS NMR, Al-27 3QMAS NMR, and O-17 MAS NMR to study fast- and slow-quenched calcium aluminosilicate glasses. Our previous work using O-17 3QMAS NMR to study lithium and sodium aluminosilicate glasses demonstrates disordering of bridging oxygen species with increasing sample fictive temperature, indicating temperature-induced rearrangement of framework units in the melt. Simple thermodynamic calculations using these results illustrate that while these structural changes may account for a portion of the experimentally-determined heat capacity of the melt, other modifications must occur to produce the observed temperature dependence of this property (Dubinsky and Stebbins 2006). The new data presented here allow us to observe changes in four-and five-coordinated aluminum and bridging and non- bridging oxygen (NBO) populations with fictive temperature in two calcium aluminosilicate glass compositions (CASx.y, where x=mol% Al2O3 and y=mol% SiO2) prepared by slow- and fast-quenching. We find that in CAS25.50 glasses, the percentage of five-coordinated Al per total Al increases from 7.6±1.9 to 9.4±2.4 and the percentage of NBO per total oxygen increases from 7.2±1.8 to 8.9±2.2 over a 150 to 200 degree fictive temperature interval. In CAS10.60 glasses representing a similar fictive temperature interval, we find that the percentage of five-coordinated Al per total Al increases from 4.0±1.0 to 4.9±1.2 and the percentage of non-bridging oxygen (NBO) per total oxygen increases from 22.8±2.3 to 23.0±2.3. Uncertainties in fitting procedures producing overlap in quantification of species in fast- and slow-quenched samples do not preclude the conclusion that robust

  20. Influence of cooking time and cooling rate on the functionality and microstructure of processed cheese spreads

    Institute of Scientific and Technical Information of China (English)

    LI Xiaodong; WU Han; LIU Huaiwei

    2007-01-01

    The objective of this work was to study the influence of cooking time and cooling rate on functionality and microstructure of processed cheese spreads. When the cooking time was 20 min, the hardness and apparent viscosity were increased, and formed a homogenous, dense, and three-dimensional protein network, and a stronger gel was formed at this time. The slow cooling can increase the hardness and apparent viscosity of products, protein wall was thicker, and network was closer, so products can formed a stronger gel structure. The influence of cooking time on the functional properties was more significant than the influence of rapid cooling.

  1. Influence of the chemical treatment in sodium clay on barrier property of propylene nanocomposites obtained by melt mixing;Influencia do tratamento quimico em argila sodica na propriedade de barreira de nanocompositos de polipropileno obtidos por mistura no fundido

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Sabina B.N. de; Marques, Maria de Fatima V., E-mail: fmarques@ima.ufrj.b [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

    2009-07-01

    In this work, the influence of the chemical treatment in sodium clay on the barrier property of polypropylene nanocomposites was evaluated. Nanocomposites of PP/clay were obtained by melting intercalation using two different chemically treated clays and the original one was mixed to PP for comparison. The change in the clay structure caused by the chemical treatment was evaluated by X-ray diffractometry. The influence of this modification on the barrier property of the obtained PP nanocomposites was evaluated by analysis of oxygen permeability. (author)

  2. Influence of water relations and growth rate on plant element uptake and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Greger, Maria [Stockholm Univ. (Sweden). Dept. of Botany

    2006-02-15

    Plant uptake of Ni, Sr, Mo, Cs, La, Th, Se, Cl and I was examined to determine how plant water relations and growth rate influence the uptake and distribution of these elements in the studied plants. The specific questions were how water uptake and growth rate influenced the uptake of various nuclides and how transpiration influenced translocation to the shoot. The knowledge gained will be used in future modelling of radionuclide leakage from nuclear waste deposits entering the ecosystem via plants. The plant studied was willow, Salix viminalis, a common plant in the areas suggested for waste disposal; since there can be clone variation, two different clones having different uptake properties for several other heavy metals were used. The plants were grown in nutrient solution and the experiments on 3-month-old plants were run for 3 days. Polyethylene glycol was added to the medium to decrease the water uptake rate, a fan was used to increase the transpiration rate, and different light intensities were used to produce different growth rates. Element concentration was analysed in roots and shoots. The results show that both the uptake and distribution of various elements are influenced in different ways and to various extents by water flow and plant growth rate, and that it is not possible from the chemical properties of these elements to know how they will react. However, in most cases increased growth rate diluted the concentration of the element in the tissue, reduced water uptake reduced the element uptake, while transpiration had no effect on the translocation of elements to the shoot. The clones did not differ in terms of either the uptake or translocation of the elements, except that I was not taken up and translocated to the shoot in one of the clones when the plant water flow or growth rate was too low. Not all of the elements were found in the plant in the same proportions as they had been added to the nutrient solution.

  3. The Influence of Radon (Gas and Progeny) and Weather Conditions on Ambient Dose Equivalent Rate.

    Science.gov (United States)

    Márquez, J L; Benito, G; Saez, J C; Navarro, N; Alvarez, A; Quiñones, J

    2016-08-13

    The purpose of this study is to identify the influence of radon (gas and progeny) on the ambient dose equivalent rate measured at the reference station ESMERALDA, where continuous measurements of the ambient dose equivalent rate (every 10 min) combined with activity concentration measurements of radon gas and radon progeny as well as meteorological parameters have been collected. This study has been performed using a correlation study based on a principal components analysis and the Spearman's rank correlation coefficient.

  4. The influence of polymerization rate on conductivity and crystallinity of electropolymerized polypyrrole

    DEFF Research Database (Denmark)

    Dyreklev, P.; Granström, M.; Inganäs, O.

    1996-01-01

    conductivity and increased crystallinity. The conductivity is also less temperature activated compared to that of the polymer grown at higher rate. X-ray diffractograms are compared to simulated diffraction data and the results are discussed in terms of increased order in the material. This may result from......We report studies on electronic conductivity and crystallinity in electropolymerized polypyrrole. Different growth rates during electropolymerization strongly influence and determine structural and electronic properties. Polymer films grown using low current density show higher electronic...

  5. Can the thermodynamic melting temperature of sucrose, glucose, and fructose be measured using rapid-scanning differential scanning calorimetry (DSC)?

    Science.gov (United States)

    Lee, Joo Won; Thomas, Leonard C; Schmidt, Shelly J

    2011-04-13

    The loss of crystalline structure in sucrose, glucose, and fructose has been shown to be due to the kinetic process of thermal decomposition (termed apparent melting), rather than thermodynamic melting. The purpose of this research was to investigate whether or not it is possible to scan quickly enough to suppress the kinetic process of thermal decomposition and reach the thermodynamic melting temperature of these sugars using a new rapid-scanning DSC. Indium, a thermodynamic melting material, and sucrose, glucose, and fructose were analyzed at three heating rates from 1 to 25 °C/min using standard DSC and at seven heating rates from 50 to 2000 °C/min using rapid-scanning DSC. Thermodynamic melting was achieved when the onset temperature (T(m onset)) of the endothermic peak leveled off to a constant value independent of heating rate. The T(m onset) for indium was constant (156.74 ± 0.42 °C) at all heating rates. In the case of fructose, the T(m onset) increased considerably until a heating rate of approximately 698 °C/min, after which the average T(m onset) for the remaining three heating rates was constant at 135.83 ± 1.14 °C. Thus, 135.83 °C is proposed to be the thermodynamic melting temperature of fructose. It is important to note that the heating rate at which this thermodynamic melting temperature is achieved is most likely influenced by the type and amount of trace components (e.g., water and salts) contained in the fructose, which are known to vary widely in sugars. In the case of sucrose and glucose, thermodynamic melting temperatures were not able to be obtained, because the upper limit heating rate used was not fast enough to suppress thermal decomposition and achieve thermodynamic melting, perhaps due to the higher apparent T(m onset) for sucrose and glucose compared to that for fructose.

  6. Melting of superheated molecular crystals

    Science.gov (United States)

    Cubeta, Ulyana; Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2017-07-01

    Melting dynamics of micrometer scale, polycrystalline samples of isobutane, dimethyl ether, methyl benzene, and 2-propanol were investigated by fast scanning calorimetry. When films are superheated with rates in excess of 105 K s-1, the melting process follows zero-order, Arrhenius-like kinetics until approximately half of the sample has transformed. Such kinetics strongly imply that melting progresses into the bulk via a rapidly moving solid-liquid interface that is likely to originate at the sample's surface. Remarkably, the apparent activation energies for the phase transformation are large; all exceed the enthalpy of vaporization of each compound and some exceed it by an order of magnitude. In fact, we find that the crystalline melting kinetics are comparable to the kinetics of dielectric α-relaxation in deeply supercooled liquids. Based on these observations, we conclude that the rate of non-isothermal melting for superheated, low-molecular-weight crystals is limited by constituent diffusion into an abnormally dense, glass-like, non-crystalline phase.

  7. Evaluating Iowa Community College Student Demographics, Characteristics, Enrollment Factors, and Educational Goals Influence on Retention Rates

    Science.gov (United States)

    Mitchley-McAvoy, Joan A.

    2012-01-01

    This study examined the influence that previously researched and affirmed persistence and early withdrawal factors such as student demographics, enrollment status factors, student characteristics, and student educational goals had on Iowa community college retention rates for the 2005, 2007, and 2009 academic years. It is the researcher's…

  8. Automatic Stand Modeling of Casting Rate Influence on Solid Phase Growth of Round Ingot inside Crystallizer

    Directory of Open Access Journals (Sweden)

    A. N. Chichko

    2006-01-01

    Full Text Available The method of calculation and results of computer dynamics modeling of solid ingot skin in a crystallizer are presented in the paper. The paper shows influence of ingot drawing rate on dynamics of solid ingot skin growth in the continuous casting machine at steel grades used at Republic Unitary Enterprise «Belarussian Metallurgical Works» (BMZ.

  9. Experiments probing the influence of air exchange rates on secondary organic aerosols derived from indoor chemistry

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Shields, H.C.

    2003-01-01

    Reactions between ozone and terpenes have been shown to increase the concentrations of submicron particles in indoor settings. The present study was designed to examine the influence of air exchange rates on the concentrations of these secondary organic aerosols as well as on the evolution...

  10. Influence of curing rate of resin composite on the bond strength to dentin

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Asmussen, E; Peutzfeldt, A

    2007-01-01

    This study determined whether the strength with which resin composite bonds to dentin is influenced by variations in the curing rate of resin composites. Resin composites were bonded to the dentin of extracted human molars. Adhesive (AdheSE, Ivoclar Vivadent) was applied and cured (10 seconds...

  11. Analyzing the Factors that Influence Persistence Rates in STEM Field, Majors: Introduction to the Symposium

    Science.gov (United States)

    Ehrenberg, Ronald G.

    2010-01-01

    To improve our understanding of the factors that influence persistence rates in STEM field majors, the Alfred P. Sloan Foundation provided a grant to the Cornell Higher Education Research Institute in 2007 to study the question. The five papers in the symposium represent the output of the project. This introduction explains the motivation for…

  12. Modeling the summertime evolution of sea-ice melt ponds

    DEFF Research Database (Denmark)

    Lüthje, Mikael; Feltham, D.L.; Taylor, P.D.;

    2006-01-01

    We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds......, vertical seepage, and horizontal permeability. The model is initialized with surface topographies derived from laser altimetry corresponding to first-year sea ice and multiyear sea ice. We predict that there are large differences in the depth of melt ponds and the area of coverage between the two types...... of ice. We also find that the vertical seepage rate and the melt rate of unponded ice are important in determining the total surface ablation and area covered by melt ponds....

  13. Modeling the summertime evolution of sea-ice melt ponds

    DEFF Research Database (Denmark)

    Lüthje, Mikael; Feltham, D.L.; Taylor, P.D.

    2006-01-01

    We present a mathematical model describing the summer melting of sea ice. We simulate the evolution of melt ponds and determine area coverage and total surface ablation. The model predictions are tested for sensitivity to the melt rate of unponded ice, enhanced melt rate beneath the melt ponds......, vertical seepage, and horizontal permeability. The model is initialized with surface topographies derived from laser altimetry corresponding to first-year sea ice and multiyear sea ice. We predict that there are large differences in the depth of melt ponds and the area of coverage between the two types...... of ice. We also find that the vertical seepage rate and the melt rate of unponded ice are important in determining the total surface ablation and area covered by melt ponds....

  14. Timing of translocation influences birth rate and population dynamics in a forest carnivore

    Science.gov (United States)

    Facka, Aaron N; Lewis, Jeffrey C.; Happe, Patricia; Jenkins, Kurt J.; Callas, Richard; Powell, Roger A.

    2016-01-01

    Timing can be critical for many life history events of organisms. Consequently, the timing of management activities may affect individuals and populations in numerous and unforeseen ways. Translocations of organisms are used to restore or expand populations but the timing of translocations is largely unexplored as a factor influencing population success. We hypothesized that the process of translocation negatively influences reproductive rates of individuals that are moved just before their birthing season and, therefore, the timing of releases could influence translocation success. Prior to reintroducing fishers (Pekania pennanti) into northern California and onto the Olympic Peninsula of Washington, we predicted that female fishers released in November and December (early) would have a higher probability of giving birth to kits the following March or April than females released in January, February, and March (late), just prior to or during the period of blastocyst implantation and gestation. Over four winters (2008–2011), we translocated 56 adult female fishers that could have given birth in the spring immediately after release. Denning rates, an index of birth rate, for females released early were 92% in California and 38% in Washington. In contrast, denning rates for females released late were 40% and 11%, in California and Washington, a net reduction in denning rate of 66% across both sites. To understand how releasing females nearer to parturition could influence population establishment and persistence, we used stochastic population simulations using three-stage Lefkovitch matrices. These simulations showed that translocating female fishers early had long-term positive influences on the mean population size and on quasi-extinction thresholds compared to populations where females were released late. The results from both empirical data and simulations show that the timing of translocation, with respect to life history events, should be considered during

  15. Influence of Four Factors on Discharge Capacity and Self-Discharge Rate of Iron Electrode

    Institute of Scientific and Technical Information of China (English)

    Dongfeng LIN; Shihai YE; Rong CAI; Deying SONG; Panwen SHEN

    2003-01-01

    Ni-Fe rechargeable batteries possess the advantages of long cycle life, high theoretical specific energy, abundant raw material,Iow price and environmental friendship. It has a wide applied perspective. The advantages, disadvantages and preparation methods of iron electrodes were summarized. The influence of four factors on discharge capacity and self-discharge rate of iron electrode were discussed by means of orthogonal experiments, galvanostatic charges and discharges. The influences of graphite on the discharge capacity and self-discharge rate of iron electrode were the most remarkable, the most unapparent influences on the discharge capacity and self-discharge rate were HPMC (hydroxy propoxy methoxy cellulose) and sodium sulphide, respectively. The aim of the present research was to study the effects of graphite, HPMC and iron powder added in the electrodes, sodium sulphide added in the electrolytes on the discharge capacity and self-discharge rate of iron electrodes.The largest discharge capacity of the iron electrodes was 488.5 mAh/g-Fe at 66.4 mA/g-Fe in the first ten cycles, and the average self-discharge rate was 0.367% per hour.

  16. Factors influencing success rate of IVF/ET:analysis of 770 treatment cycles

    Institute of Scientific and Technical Information of China (English)

    叶碧绿; 林金菊; 周颖; 黄学峰; 赵军招; 郑菊芬; 林文琴

    2002-01-01

    Objective: To evaluate the factors influencing success ra te of in vitro fertilization /embryo transfer(IVF/ET).Methods: A retrospective study of 770 consecutive cycles under gone IVF/ET or intracytoplasmic sperm injection (ICSI) from March 1999 to June 2 001.Estradiol and progesterone concentrations on the day of hCG administration w ere measured. Factors effecting embryo transfer on the effects of clinical pregn ancy rate were evaluated.Results: The overall clinical pregnancy rate in 770 cycles was 40.8%. Take home baby rate was 31%. No significantly differences rate were obse rved between groups with different estradiol levels.If the progesterone concentr ation on the day of hCG administration was >6.36 nmol/L, the implantation and cl inical pregnancy rate was lower(P<0.003). The lowest clinical pregnancy rat e was observed when the duration of infertility was ≥10 years. The average numb er of embryos transferred was 2.23±0.83.Conclusion: This study demonstrated that the most important fac tor on clinical pregnancy rate was low progesterone concentration on the day of hCG administration. The other two important variables influencing success rate o f IVF/ET were the duration of infertility, the number of high-grade embryos tra nsferred.

  17. Analysis of Factors Influencing Pregnancy Rate in Frozen-thawed Embryo Transfer

    Institute of Scientific and Technical Information of China (English)

    Lu LI; Xiao-xi SUN; Jun-ling CHEN; Xiao-hong GAO; Yong-wei WANG; Jie-wei TAO; Li-nan CHENG

    2004-01-01

    Objective To analyse factors influencing the outcome of frozen-thawed embryo transfer (FET)Method A retrospective analysis was performed in our center on 129 thawing cycles from March 2001 to April 2003. The related parameters were compared between conceived and non-conceived cycles.Results There were totally 129 clinical pregnancies in these transfers (pregnancy rate: 27.1%). Frozen-thawed embryos were transferred to natural cycles and CC cycling and hormone replacement treatment had equal success. Groups of IVF and ICSI did not differ significantly in pregnancy rates (P>0. 05). The pregnancy rates for one, two, three and four pre-embryos transfer were 0, 20.0%,44.1% and 75.0%,respectively (P<0. 05). There were statistical differences between pregnancy group or non- pregnancy group in the endometrial thickness, CES, CES/No. Of embryo. A higher pregnancy rate was observed in embryo transfers which had at least one 4-cell grade I embryo (d 2)(P<0.01). Conclusions The most important factors influencing the implantation rate and pregnancy rate of frozen-thawed embryo transfer are age, endometrium thickness, and the number, morphology and growth rate of transferred frozen embryos of women participants.

  18. Frame rate of motion picture and its influence on speech perception

    Science.gov (United States)

    Nakazono, Kaoru

    1996-03-01

    The preservation of QoS for multimedia traffic through a data network is a difficult problem. We focus our attention on video frame rate and study its influence on speech perception. When sound and picture are discrepant (e.g., acoustic `ba' combined with visual `ga'), subjects perceive a different sound (such as `da'). This phenomenon is known as the McGurk effect. In this paper, the influence of degraded video frame rate on speech perception was studied. It was shown that when frame rate decreases, correct hearing is improved for discrepant stimuli and is degraded for congruent (voice and picture are the same) stimuli. Furthermore, we studied the case where lip closure was always captured by the synchronization of sampling time and lip position. In this case, frame rate has little effect on mishearing for congruent stimuli. For discrepant stimuli, mishearing is decreased with degraded frame rate. These results indicate that stiff motion of lips resulting from low frame rate cannot give enough labial information for speech perception. In addition, the effect of delaying the picture to correct for low frame rate was studied. The results, however, were not as definitive as expected because of compound effects related to the synchronization of sound and picture.

  19. Purification of Niobium by Electron Beam Melting

    Science.gov (United States)

    Sankar, M.; Mirji, K. V.; Prasad, V. V. Satya; Baligidad, R. G.; Gokhale, A. A.

    2016-06-01

    Pure niobium metal, produced by alumino-thermic reduction of niobium oxide, contains various impurities which need to be reduced to acceptable levels to obtain aerospace grade purity. In the present work, an attempt has been made to refine niobium metals by electron beam drip melting technique to achieve purity confirming to the ASTM standard. Input power to the electron gun and melt rate were varied to observe their combined effect on extend of refining and loss of niobium. Electron beam (EB) melting is shown to reduce alkali metals, trace elements and interstitial impurities well below the specified limits. The reduction in the impurities during EB melting is attributed to evaporation and degassing due to the combined effect of high vacuum and high melt surface temperature. The % removal of interstitial impurities is essentially a function of melt rate and input power. As the melt rate decreases or input power increases, the impurity levels in the solidified niobium ingot decrease. The EB refining process is also accompanied by considerable amount of niobium loss, which is attributed to evaporation of pure niobium and niobium sub-oxide. Like other impurities, Nb loss increases with decreasing melt rate or increase in input power.

  20. Shock-induced melting and rapid solidification

    Energy Technology Data Exchange (ETDEWEB)

    Nellis, W.J.; Gourdin, W.H.; Maple, M.B.

    1987-08-01

    Model calculations are presented to estimate that approx.50 GPa is required to completely shock melt metal powders with quenching at rates up to 10/sup 8/ K/s. Experiments are discussed for powders of a Cu-Zr alloy compacted in the usual way at 16 GPa and melted by shocking to 60 GPa. 12 refs.

  1. Melting of Transition Metals

    Energy Technology Data Exchange (ETDEWEB)

    Ross, M; Japel, S; Boehler, R

    2005-04-11

    We review the transition melting studies carried out at Mainz, and describe a recently developed model used to explain that the relatively low melting slopes are due to the partially filled d-bands, and the persistence of the pressure induced s-d transition. The basic tenets of the model have now been reconfirmed by new measurements for Cu and Ni. The measurements show that Cu which has a filled 3d-band, has a melt slope that is about 2.5 greater than its neighbor Ni. In the case of Mo, the apparent discrepancy of DAC melting measurements with shock melting can be explained by accounting for the change in melt slope due to the bcc-cp transition observed in the shock studies. The Fe melt curve is revisited. The possible relevance of the Jahn-Teller effect and recently observed transition metal melts with Icosahedral Short-Range Order (ISRO) is discussed.

  2. Can reptile embryos influence their own rates of heating and cooling?

    Science.gov (United States)

    Du, Wei-Guo; Tu, Ming-Chung; Radder, Rajkumar S; Shine, Richard

    2013-01-01

    Previous investigations have assumed that embryos lack the capacity of physiological thermoregulation until they are large enough for their own metabolic heat production to influence nest temperatures. Contrary to intuition, reptile embryos may be capable of physiological thermoregulation. In our experiments, egg-sized objects (dead or infertile eggs, water-filled balloons, glass jars) cooled down more rapidly than they heated up, whereas live snake eggs heated more rapidly than they cooled. In a nest with diel thermal fluctuations, that hysteresis could increase the embryo's effective incubation temperature. The mechanisms for controlling rates of thermal exchange are unclear, but may involve facultative adjustment of blood flow. Heart rates of snake embryos were higher during cooling than during heating, the opposite pattern to that seen in adult reptiles. Our data challenge the view of reptile eggs as thermally passive, and suggest that embryos of reptile species with large eggs can influence their own rates of heating and cooling.

  3. Can reptile embryos influence their own rates of heating and cooling?

    Directory of Open Access Journals (Sweden)

    Wei-Guo Du

    Full Text Available Previous investigations have assumed that embryos lack the capacity of physiological thermoregulation until they are large enough for their own metabolic heat production to influence nest temperatures. Contrary to intuition, reptile embryos may be capable of physiological thermoregulation. In our experiments, egg-sized objects (dead or infertile eggs, water-filled balloons, glass jars cooled down more rapidly than they heated up, whereas live snake eggs heated more rapidly than they cooled. In a nest with diel thermal fluctuations, that hysteresis could increase the embryo's effective incubation temperature. The mechanisms for controlling rates of thermal exchange are unclear, but may involve facultative adjustment of blood flow. Heart rates of snake embryos were higher during cooling than during heating, the opposite pattern to that seen in adult reptiles. Our data challenge the view of reptile eggs as thermally passive, and suggest that embryos of reptile species with large eggs can influence their own rates of heating and cooling.

  4. Influence of size on the rate of mesoporous electrodes for lithium batteries.

    Science.gov (United States)

    Ren, Yu; Armstrong, A Robert; Jiao, Feng; Bruce, Peter G

    2010-01-27

    High power rechargeable lithium batteries are a key target for transport and load leveling, in order to mitigate CO(2) emissions. It has already been demonstrated that mesoporous lithium intercalation compounds (composed of particles containing nanometer diameter pores separated by walls of similar size) can deliver high rate (power) and high stability on cycling. Here we investigate how the critical dimensions of pore size and wall thickness control the rate of intercalation (electrode reaction). By using mesoporous beta-MnO(2), the influence of these mesodimensions on lithium intercalation via single and two-phase intercalation processes has been studied in the same material enabling direct comparison. Pore size and wall thickness both influence the rate of single and two-phase intercalation mechanisms, but the latter is more sensitive than the former.

  5. Photosynthetic rates influence the population dynamics of understory herbs in stochastic light environments.

    Science.gov (United States)

    Westerband, Andrea C; Horvitz, Carol C

    2017-02-01

    Temporal variability in light from gaps in the tree canopy strongly influences the vital rates of understory plants. From 2012 to 2015, we estimated the size-specific vital rates of two herbs, Calathea crotalifera and Heliconia tortuosa, over a range of light environments. We estimated maximum photosynthetic capacity (Amax ) for a subset of individuals each year during three annual censuses, and modelled future size as a linear function of current size (a plant trait that changes ontogenetically), canopy openness (an environmental variable), and Amax (a potentially plastic physiological trait). We estimated what the demographic success would be of a population comprised of individuals with a particular fixed Amax for each of several levels of canopy openness if the environment remained constant, by evaluating corresponding Integral Projection Models and their deterministic growth rates (λ). We then estimated their demographic success in the stochastic light environment (λS ) and its elasticities. As light increased, deterministic λ increased for Calathea by 33% but decreased for Heliconia by 52%, and increasing Amax had no effect on λ for Calathea but increased λ for Heliconia in low light. As Amax increased, λS increased for Heliconia, but not Calathea. We also investigated whether photosynthetic rates would influence the elasticities of λS, including its response to perturbation of vital rates in each environment (E(S)β ), vital rates over all environments (E(S) ), and variability of vital rates among environments (E(S)(σ) ). E(S) , E(S)(σ) , and E(S)β were influenced by Amax for Heliconia but not Calathea. Events that affect some vital rates in high light have a greater impact on overall fitness than events that affect the same vital rates in shady environments, and there is greater potential for selection on traits of large individuals in high light than in low light for Heliconia, while the reverse was true for Calathea. Photosynthetic rates

  6. Influence of the crucible geometry on the shape of the melt crystal interface during growth of sapphire crystal using a heat exchanger method

    Science.gov (United States)

    Chen, Jyh-Chen; Lu, Chung-Wei

    2004-05-01

    Computer simulations using the commercial code FIDAP, which is based on finite element techniques, were performed to investigate the effect of the shape of the crucible on the temperature distribution, velocity distribution and shape of the melt-crystal interface, during the application of the heat exchanger method (HEM) of growing sapphire crystals. Heat transfer from the furnace to the crucible and heat extraction from the heat exchanger can be modeled by the convection boundary conditions. Cylindrical crucibles with differently curved corners at their base are considered. The curved base of the crucible decreases the convexity of the melt-crystal interface and suppresses the appearance of "hot spots". A hemispherically shaped crucible base yields the lowest maximum convexity. The variation in convexity of the melt-crystal interface is less abrupt for a cylindrical crucible with curved corners at the base than one without curved corners. The effects of the thickness and the conductivity of the crucible are also addressed. The convexity of the melt-crystal interface decreases as the thickness of the crucible wall increases. The convexity also declines as the conductivity of the crucible increases.

  7. Economizer system cost effectiveness: Accounting for the influence of ventilation rate on sick leave

    Energy Technology Data Exchange (ETDEWEB)

    Fisk, William J.; Seppanen, Olli; Faulkner, David; Huang, Joe

    2003-06-01

    This study estimated the health, energy, and economic benefits of an economizer ventilation control system that increases outside air supply during mild weather to save energy. A model of the influence of ventilation rate on airborne transmission of respiratory illnesses was used to extend the limited data relating ventilation rate with illness and sick leave. An energy simulation model calculated ventilation rates and energy use versus time for an office building in Washington, DC with fixed minimum outdoor air supply rates, with and without an economizer. Sick leave rates were estimated with the disease transmission model. In the modeled 72-person office building, our analyses indicate that the economizer reduces energy costs by approximately $2000 and, in addition, reduces sick leave. The financial benefit of the decrease in sick leave is estimated to be between $6,000 and $16,000. This modelling suggests that economizers are much more cost effective than currently recognized.

  8. [The applicability of sucrose laurate in hot-melt technology].

    Science.gov (United States)

    Lang, Péter; Szuts, Angéla; Ambrus, Rita; Szabóné, Révész Piroska

    2011-01-01

    Nowadays, one of the most important task of the pharmaceutical technology is to optimize the dissolution of active ingredients, because most of the drug candidates have a poorly water solubility and hence a slow absorption. According to the latest examinations, the bioavailability of poorly water soluble drugs can be increased significantly by using surfactants or the mixture of surfactants and polymers. Nowadays, surfactants (like polysorbates) are generally used in the production of solid dispersions, so the use of surface-active sucrose esters can be resulted an innovative solution in the pharmaceutical technology. The aim of our investigation was to examine the applicability of sucrose laurate in hot-melt technology in order to influence the crystalline structure and dissolution rate of a poorly water soluble drug (gemfibrosil) having low-melting point. The results of the X-ray powder diffractometry have showed that the sucrose laurate had no significant effect on the crystallization degree of the drug which is important in case of the stability. On the bases of the results of in-vitro dissolution studies, it can be concluded that the sucrose laurate (using minimum 5%) can be well applied in hot-melt technology with carriers having characteristic melting point (e.g. Macrogol) to increase the dissolution rate of poorly soluble drugs.

  9. On the determination of the equilibrium melting temperature of polybutylene terephthalate (PBT)

    Energy Technology Data Exchange (ETDEWEB)

    Luz, Alexandre P. da; Bretas, Rosario E.S. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Dept. de Engenharia de Materiais. Ncleo de Reologia e Processamento de Polimeros]. E-mail: bretas@power.ufscar.br; Marinelli, Alessandra L. [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil). Centro de Caracterizacao e Desenvolvimento de Materiais]. E-mail: alucas@ccdm.ufscar.br; Farah, Marcelo [Braskem S.A., Sao Paulo, SP (Brazil)]. E-mail: marcelo.farah@braskem.com.br; Torriani, Iris [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas (Brazil)]. E-mails: tomas@lnls.br; torriani@lnls.br

    2005-07-01

    In this work, the equilibrium melting temperature, T{sub m}{sup 0}, of a PBT sample using the classical Hoffman-Weeks (H-W) Method and the Method proposed by Marand and Hoffman was evaluated. We also investigated the influence of the pre-melting temperature, T{sub pm}, that is the temperature of the melt prior to the isothermal crystallization, and different rates during the heating DSC scan, on the values of the T{sub m}{sup 0} calculated. The results show that the evaluation of the equilibrium melting temperatures of polymers is quite dependent of the experimental conditions used to crystallize the sample and the method used to evaluate it. (author)

  10. An empirical study of factors influencing total unemployment rate in comparison to youth unemployment rate in selected EU member-states

    OpenAIRE

    Kokotović, Filip

    2016-01-01

    The issue of youth unemployment rate in the heavily indebted and less developed EU countries is currently on the margins of both media interest and policy debates. This paper compares the influence of several economic variables on the total unemployment rate and the youth unemployment rate. The countries that are studied are three countries with the highest youth unemployment rate: Greece, Croatia and Spain, and three countries with the lowest youth unemployment rate: Germany, ...

  11. Cognitive, Parent and Teacher Rating Measures of Executive Functioning: Shared and Unique Influences on School Achievement.

    Science.gov (United States)

    Dekker, Marielle C; Ziermans, Tim B; Spruijt, Andrea M; Swaab, Hanna

    2017-01-01

    Very little is known about the relative influence of cognitive performance-based executive functioning (EF) measures and behavioral EF ratings in explaining differences in children's school achievement. This study examined the shared and unique influence of these different EF measures on math and spelling outcome for a sample of 84 first and second graders. Parents and teachers completed the Behavior Rating Inventory of Executive Function (BRIEF), and children were tested with computer-based performance tests from the Amsterdam Neuropsychological Tasks (ANT). Mixed-model hierarchical regression analyses, including intelligence level and age, showed that cognitive performance and teacher's ratings of working memory and shifting concurrently explained differences in spelling. However, teacher's behavioral EF ratings did not explain any additional variance in math outcome above cognitive EF performance. Parent's behavioral EF ratings did not add any unique information for either outcome measure. This study provides support for the ecological validity of performance- and teacher rating-based EF measures, and shows that both measures could have a complementary role in identifying EF processes underlying spelling achievement problems. The early identification of strengths and weaknesses of a child's working memory and shifting capabilities, might help teachers to broaden their range of remedial intervention options to optimize school achievement.

  12. Cognitive, Parent and Teacher Rating Measures of Executive Functioning: Shared and Unique Influences on School Achievement

    Science.gov (United States)

    Dekker, Marielle C.; Ziermans, Tim B.; Spruijt, Andrea M.; Swaab, Hanna

    2017-01-01

    Very little is known about the relative influence of cognitive performance-based executive functioning (EF) measures and behavioral EF ratings in explaining differences in children's school achievement. This study examined the shared and unique influence of these different EF measures on math and spelling outcome for a sample of 84 first and second graders. Parents and teachers completed the Behavior Rating Inventory of Executive Function (BRIEF), and children were tested with computer-based performance tests from the Amsterdam Neuropsychological Tasks (ANT). Mixed-model hierarchical regression analyses, including intelligence level and age, showed that cognitive performance and teacher's ratings of working memory and shifting concurrently explained differences in spelling. However, teacher's behavioral EF ratings did not explain any additional variance in math outcome above cognitive EF performance. Parent's behavioral EF ratings did not add any unique information for either outcome measure. This study provides support for the ecological validity of performance- and teacher rating-based EF measures, and shows that both measures could have a complementary role in identifying EF processes underlying spelling achievement problems. The early identification of strengths and weaknesses of a child's working memory and shifting capabilities, might help teachers to broaden their range of remedial intervention options to optimize school achievement. PMID:28194121

  13. Melt and Chemical Transport in the Mantle: Insights from Deglaciation-Induced Melting Perturbations in Iceland

    Science.gov (United States)

    Eason, D. E.; Ito, G.; Sinton, J. M.

    2011-12-01

    Eruptive products represent a time-averaged view of the melting region and melt migration processes, making numerous fundamental parameters of the melt system difficult to constrain. Temporal and spatial variations in melting provide potential windows into this obscure region of the Earth by preferentially sampling melts from different regions of the mantle or mixing melts over different length-scales. We present a newly extended geochemical time series from the Western Volcanic Zone (WVZ) of Iceland, which experienced a short-lived melting perturbation due to glacial unloading during the last major deglaciation (~15-10 ka). Glacial unloading during this period led to increased degrees of melting particularly in the shallow mantle, which is manifest as an observed increase in volcanic production up to 30 times the steady-state value, decreased levels of highly to moderately incompatible element ratios (e.g., a 35-50% decrease in Nb/Y, with the greatest change occurring in the northernmost WVZ), and elevated SiO2 and CaO concentrations (~0.8 wt. % and ~1.9 wt. % increase in average oxide concentrations respectively) during and immediately following deglaciation. Although eruptive productivity returns to steady-state values within ~3000 yr following deglaciation, the incompatible element concentrations in erupted lavas gradually increase throughout the post-glacial period. We exploit this short-lived melting perturbation to examine and constrain knowledge of fundamental characteristics of melt generation and transport, including mantle permeability, melt ascent rates, depth-dependent melting functions (dF/dP), and the nature of chemical transport and melt mixing in the system. Using conservation equations describing the generation and porous flow of melt in a viscous matrix, we model melt migration in the mantle during and after ice sheet removal, as well as trace element transport for both equilibrium and disequilibrium transport end members. The predicted

  14. A benchmark initiative on mantle convection with melting and melt segregation

    Science.gov (United States)

    Schmeling, Harro; Dannberg, Juliane; Dohmen, Janik; Kalousova, Klara; Maurice, Maxim; Noack, Lena; Plesa, Ana; Soucek, Ondrej; Spiegelman, Marc; Thieulot, Cedric; Tosi, Nicola; Wallner, Herbert

    2016-04-01

    In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we carry out a benchmark comparison. The reference model is taken from the mantle convection benchmark, cases 1a to 1c (Blankenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and Rayleigh numbers of 104 to 10^6. Melting is modelled using a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) five cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 is identical to case 1 except that latent heat is switched on. Case 3 includes batch melting, melt buoyancy (melt Rayleigh number Rm) and depletion buoyancy, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms), the maximum and the total melt volume and qm approaching a statistical steady state. Case 4 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases are carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction formulation. For cases 1 - 3 very good agreement

  15. Significance and influence of the ambient temperature as a rate factor of steel reinforcement corrosion

    Indian Academy of Sciences (India)

    V Živica

    2002-10-01

    The rate of corrosion of reinforcement being an electrochemical process, undoubtedly is dependent even on the level of the ambient temperature. Therefore, the ambient temperature seems to be an important factor of the corrosion rate and the durability of the reinforced concrete structures in aggressive environment. The present data on the influence and significance of the ambient temperature in the process of corrosion of reinforcement of the reinforced structures are surprisingly limited and poor. It seems that it is supposed to be a simple increase of corrosion rate when the ambient temperature is increased. The lack of information was a motivation for the present study. It was aimed at the experimental research of the influence of the increase of the ambient temperature on the rate of chloride induced corrosion of steel reinforcement. The results obtained show that the influence of the studied factor is more complex showing an acceleration effect till a temperature of 40°C diversified by the inhibition effects with further increase of the ambient temperature.

  16. Influence of cooling rate on cracking and plastic deformation during impact and indentation of borosilicate glasses.

    Science.gov (United States)

    Zehnder, Christoffer; Bruns, Sebastian; Peltzer, Jan-Niklas; Durst, Karsten; Korte-Kerzel, Sandra; Möncke, Doris

    2017-03-01

    The influence of a changing glass topology on local mechanical properties was studied in a multi-technique nanomechanical approach. The glass response against sharp contacts can result in structural densification, plastic flow or crack initiation. Using instrumented indentation testing, the mechanical response was studied in different strain rate regimes for a sodium-boro-silicate glass (NBS) exhibiting altering structures due to varying processing conditions. Comparison with data from former studies as well as with literature data on other glass structures helped to elucidate the role of the borate and silicate sub-networks and to understand the overall mechanical properties of the mixed glass systems. A peculiarity of some of the NBS glasses tested in this study is the fact that the connectivity of the borate and silicate entities depends on the sample’s thermal history. While the influence on macroscopic material properties such as E and H is minor, the onset of cracking indeed is influenced by those structural changes within the glass. Rapidly quenched glass shows an improved crack resistance, which is even more pronounced at high strain rates. Studies on various processing conditions further indicate that this transition is closely related to the cooling rate around Tg. The strain rate dependence of cracking is discussed in terms of the occurrence of shear deformation and densification.

  17. Ocean Properties and Submarine Melt of Ice Shelves in a High-Arctic Fiord (Milne Fiord)

    Science.gov (United States)

    Hamilton, A.; Mueller, D.; Laval, B.

    2014-12-01

    The role of ambient stratification, the vertical distribution of heat, and fiord circulation on submarine melt rates in glacial fiords in the Canadian Arctic are largely unknown despite recent widespread collapse of ice shelves in this region. A 3-year field study was conducted to investigate ocean influence on ice loss from an ice shelf and glacier tongue in Milne Fiord (82oN), Ellesmere Island. Direct ocean observations of the sub-ice cavities from through-ice profiles showed a vertically stratified water column consisting of a perennial fresh ice-dammed epishelf lake at the surface, above cold relatively fresh Polar Water, and warm saline waters from the upper halocline of the Atlantic layer at depth. The broad continental shelf and a topographic sill prevented the warmest waters of the Atlantic layer from entering the 450 m deep fiord. Meltwater concentrations were highest near the glacier grounding line, with meltwater exported at depth due to the strong ambient stratification. There was little evidence of increased buoyancy-driven melt in summer from subglacial discharge as observed in sub-Arctic fiords (e.g. southern Greenland), suggesting that circulation in high-latitude fiords is largely melt-driven convection with less pronounced seasonality. Basal melt rates estimated using three methods, meltwater flux, divergence of ice flux, and an ocean thermodynamic model, were broadly consistent. Average melt rates of 0.75 ± 0.46 m a-1 and 1.14 ± 0.83 m a-1 were found for the Milne Ice Shelf and Milne Glacier Tongue, respectively, although showed high spatial variability. The highest melt rates (~4 m a-1) were found near the glacier grounding line and were driven by warm upper halocline waters. Similar melt rates occurred in near-surface waters driven by solar heating of the epishelf lake, enhancing melt along the margins of the glacier tongue and the landward edge of the ice shelf. The Milne Ice Shelf and Milne Glacier Tongue are in a state of negative mass

  18. Oscillations of the crystal-melt interface caused by harmonic oscillations of the pulling rate for the cylindrical phase of crystal growth

    Science.gov (United States)

    Vasil'ev, M. G.

    2017-02-01

    A technique for measuring the crystal cross-sectional area with a weight sensor based on the difference between its readings at the extreme rod positions in the stepwise and continuous modes of modulation of the pulling rate is proposed for the low-thermal gradient Czochralski method. A change in the crystallization rate at harmonic oscillations of the pulling rate is estimated with the aim of conserving the quality of the growing crystal for this measurement method.

  19. Physicochemical properties influencing denitrification rate and microbial activity in denitrification bioreactors

    Science.gov (United States)

    Schmidt, C. A.

    2012-12-01

    The use of N-based fertilizer will need to increase to meet future demands, yet existing applications have been implicated as the main source of coastal eutrophication and hypoxic zones. Producing sufficient crops to feed a growing planet will require efficient production in combination with sustainable treatment solutions. The long-term success of denitrification bioreactors to effectively remove nitrate (NO¬3), indicates this technology is a feasible treatment option. Assessing and quantifying the media properties that affect NO¬3 removal rate and microbial activity can improve predictions on bioreactor performance. It was hypothesized that denitrification rates and microbial biomass would be correlated with total C, NO¬3 concentration, metrics of organic matter quality, media surface area and laboratory measures of potential denitrification rate. NO¬3 removal rates and microbial biomass were evaluated in mesocosms filled with different wood treatments and the unique influence of these predictor variables was determined using a multiple linear regression analysis. NO3 reduction rates were independent of NO¬3 concentration indicating zero order reaction kinetics. Temperature was strongly correlated with denitrification rate (r2=0.87; Q10=4.7), indicating the variability of bioreactor performance in differing climates. Fiber quality, and media surface area were strong (R>0.50), unique predictors of rates and microbial biomass, although C:N ratio and potential denitrification rate did not predict actual denitrification rate or microbial biomass. Utilizing a stepwise multiple linear regression, indicates that the denitrification rate can be effectively (r2=0.56;pbioreactors to achieve significant N load reductions in large watersheds. The nitrate reduction rate as a function of groundwater temperature for all treatments. Correlations between nitrate reduction rate and properties of carbon media;

  20. Influence of carrier gas flow rate on carbon nanotubes growth by TCVD with Cu catalyst

    Directory of Open Access Journals (Sweden)

    S.A. Khorrami

    2016-07-01

    Full Text Available Carbon nanotubes (CNTs were grown on copper catalyst by thermal chemical vapor deposition (TCVD using H2 and N2 as carrier gases. CNTs with different morphologies were observed using different carrier gas flow rates. The influence of carrier gas flow rates on the structure of carbon nanotubes was compared. Catalyst nanolayer was sputtered on mirror polished silicon wafers. The catalyst film thickness was determined by using the Rutherford Back Scattering (RBS technique. Ethanol as carbon source has been used. The surface morphology and nanostructure were studied by Scanning Electron Microscopy (SEM, Raman Spectroscopy, Tunneling Electron Microscopy (TEM and Atomic Force Microscopy (AFM. Results indicated that the amounts of deposited carbon decrease with increasing flow rates. These results showed that CNTs’ length decreased with increasing flow rates. Results suggest that Cu nanolayer is suitable as catalyst due to the fact that CNTs are monotonous.

  1. An in vivo assessment of the influence of needle gauges on endodontic irrigation flow rate

    Directory of Open Access Journals (Sweden)

    Velayutham Gopikrishna

    2016-01-01

    Statistical Analysis Used: The following tests were used for the statistical analysis: Independent sample "T" test, one-way ANOVA test, and post hoc multiple comparison was carried out using Tukey′s honest significant difference (HSD test using Statistical Package for the Social Sciences (SPSS version 16 for Windows. Results: The average flow rate of 26 gauge was 0.27 mLs−1 , of 27 gauge was 0.19 mLs−1 , and of 30 gauge was 0.09 mls−1 . There was statistical significance among the gauges (P < 0.001. 26 gauge had highest flow rate when compared with other groups followed by 27 gauge and 30 gauge respectively. The operator variability for flow rate of three endodontic irrigation needle gauges (26 gauge, 27 gauge, and 30 gauge was found to be not significant. Conclusions: Needle gauge has significant influence on endodontic irrigation flow rate.

  2. 驻极处理对熔喷空气过滤材料过滤性能的影响%The influence on filtration efficiency of melt-blown air filter material after electrets treatment

    Institute of Scientific and Technical Information of China (English)

    刘超

    2013-01-01

      The structure characteristic and filtration mechanism of melt-blown filtration materials were introduced. The influence of melt-blown filtration material with electrets treatment on the filtration efficiency was studied.The electrets treatment could enhance filtration efficiency of the material greatly and almost re-main absorption resistance stable , the filtration efficiency of the material would increase by rise of elec-trets voltage.The filtration efficiency of melt-blown filtration material with electrets treatment was high-er than that of the melt-blown filtration material spray nanofiber and the absorption resistance of the melt-blown filtration material spray nanofiber was higher than the national standard and larger than that of the former.The electrets treatment was an important process on melt-blown air filter material and could be applied on production widely .%  介绍了熔喷过滤材料的结构特点和过滤机理,研究了驻极处理对熔喷过滤材料过滤性能的影响。结果表明:驻极处理能够大幅度地提高熔喷空气过滤材料的过滤效率而保持呼吸阻力几乎不变,并随着驻极电压的增加,过滤效率增大;在熔喷空气过滤材料上喷涂纳米纤维后,其过滤效率低于经驻极处理的熔喷空气过滤材料,而呼吸阻力却急剧增大,远远超过国家标准(≤350 Pa)的要求。驻极处理方法是熔喷空气过滤材料重要的一种处理工艺,可在生产中广泛应用。

  3. Striking variations in consultation rates with general practice reveal family influence

    Directory of Open Access Journals (Sweden)

    Spreeuwenberg Peter

    2007-01-01

    Full Text Available Abstract Background The reasons why patients decide to consult a general practitioner vary enormously. While there may be individual reasons for this variation, the family context has a significant and unique influence upon the frequency of individuals' visits. The objective of this study was to explore which family factors can explain the differences between strikingly high, and correspondingly low, family consultation rates in families with children aged up to 21. Methods Data were used from the second Dutch national survey of general practice. This survey extracted from the medical records of 96 practices in the Netherlands, information on all consultations with patients during 2001. We defined, through multilevel analysis, two groups of families. These had respectively, predominantly high, and low, contact frequencies due to a significant family influence upon the frequency of the individual's first contacts. Binomial logistic regression analyses were used to analyse which of the family factors, related to shared circumstances and socialisation conditions, can explain the differences in consultation rates between the two groups of families. Results In almost 3% of all families, individual consultation rates decrease significantly due to family influence. In 11% of the families, individual consultation rates significantly increase due to family influence. While taking into account the health status of family members, family factors can explain family consultation rates. These factors include circumstances such as their economic status and number of children, as well as socialisation conditions such as specific health knowledge and family beliefs. The chance of significant low frequencies of contact due to family influences increases significantly with factors such as, paid employment of parents in the health care sector, low expectations of general practitioners' care for minor ailments and a western cultural background. Conclusion Family

  4. Influence of the FEC Channel Coding on Error Rates and Picture Quality in DVB Baseband Transmission

    Directory of Open Access Journals (Sweden)

    T. Kratochvil

    2006-09-01

    Full Text Available The paper deals with the component analysis of DTV (Digital Television and DVB (Digital Video Broadcasting baseband channel coding. Used FEC (Forward Error Correction error-protection codes principles are shortly outlined and the simulation model applied in Matlab is presented. Results of achieved bit and symbol error rates and corresponding picture quality evaluation analysis are presented, including the evaluation of influence of the channel coding on transmitted RGB images and their noise rates related to MOS (Mean Opinion Score. Conclusion of the paper contains comparison of DVB channel codes efficiency.

  5. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Science.gov (United States)

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  6. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Directory of Open Access Journals (Sweden)

    Marvin Schmidt

    2016-06-01

    Full Text Available This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  7. Melt analysis of mismatch amplification mutation assays (Melt-MAMA: a functional study of a cost-effective SNP genotyping assay in bacterial models.

    Directory of Open Access Journals (Sweden)

    Dawn N Birdsell

    Full Text Available Single nucleotide polymorphisms (SNPs are abundant in genomes of all species and biologically informative markers extensively used across broad scientific disciplines. Newly identified SNP markers are publicly available at an ever-increasing rate due to advancements in sequencing technologies. Efficient, cost-effective SNP genotyping methods to screen sample populations are in great demand in well-equipped laboratories, but also in developing world situations. Dual Probe TaqMan assays are robust but can be cost-prohibitive and require specialized equipment. The Mismatch Amplification Mutation Assay, coupled with melt analysis (Melt-MAMA, is flexible, efficient and cost-effective. However, Melt-MAMA traditionally suffers from high rates of assay design failures and knowledge gaps on assay robustness and sensitivity. In this study, we identified strategies that improved the success of Melt-MAMA. We examined the performance of 185 Melt-MAMAs across eight different pathogens using various optimization parameters. We evaluated the effects of genome size and %GC content on assay development. When used collectively, specific strategies markedly improved the rate of successful assays at the first design attempt from ~50% to ~80%. We observed that Melt-MAMA accurately genotypes across a broad DNA range (~100 ng to ~0.1 pg. Genomic size and %GC content influence the rate of successful assay design in an independent manner. Finally, we demonstrated the versatility of these assays by the creation of a duplex Melt-MAMA real-time PCR (two SNPs and conversion to a size-based genotyping system, which uses agarose gel electrophoresis. Melt-MAMA is comparable to Dual Probe TaqMan assays in terms of design success rate and accuracy. Although sensitivity is less robust than Dual Probe TaqMan assays, Melt-MAMA is superior in terms of cost-effectiveness, speed of development and versatility. We detail the parameters most important for the successful application of

  8. Melting of transition metals at high pressure and the influence of liquid frustration. I. The late metals Cu, Ni and Fe

    Energy Technology Data Exchange (ETDEWEB)

    Ross, M; Boehler, R; Errandonea, D

    2007-03-15

    This report focuses on the role that frustration, or preferred liquid local causes ordering, plays in the melting of transition metals. Specifically, Cu, Ni and Fe. It is proposed that for liquids of metals with partially filled d-bands (Ni and Fe) frustration caused by Peierls/Jahn-Teller distortion and pressure-induced s-d electron promotion provides a mechanism for creating and enhancing the stability of local structures. At the most elementary level, liquid structures are essentially impurities that lower the freezing point. In the case of transition metals with partially filled d-bands, the application of pressure induces s-d electron promotion increases the concentration of local structures. This leads to melting slopes for Ni and Fe that are considerably lower than measured for Cu, and lower than for theoretical predictions employing models in which liquid structures are neglected.

  9. Influence of body temperature on bacterial growth rates in experimental pneumococcal meningitis in rabbits.

    OpenAIRE

    Small, P M; Täuber, M G; Hackbarth, C J; Sande, M A

    1986-01-01

    We examined the role of fever as a host defense in experimental pneumococcal meningitis in rabbits. Twelve hours after intracisternal inoculation of an encapsulated type 3 Streptococcus pneumoniae strain, body temperature was manipulated by using two different anesthetic drugs: pentobarbital, which did not affect temperature, and urethane, which mitigated the febrile response to infection. Growth rates of pneumococci in cerebrospinal fluid were dramatically influenced by modification of the f...

  10. Factors influencing the adolescent pregnancy rate in the Greater Giyani Municipality, Limpopo Province – South Africa

    OpenAIRE

    Lenny Mushwana; Lydia Monareng; Solina Richter; Helene Muller

    2015-01-01

    A quantitative, descriptive and explorative survey was conducted to determine factors that influence adolescent pregnancy rate among teenage girls (n = 147) attending four high schools in the Greater Giyani Municipality in South Africa. Data was collected using a validated questionnaire which had a reliability of 0.65. Response frequency distributions, two-way frequency tables, Chi-square tests and Cochran–Armitage Trend Tests were used to determine the effect with the demographic characteris...

  11. Influence of Surface Gas-Phase Rare Earth Permeation Plus Laser Melting Solidification on Microstructure and Corrosion Resistance of Pure Iron

    Institute of Scientific and Technical Information of China (English)

    许越; 纪红; 陈湘; 赵连城

    2002-01-01

    The samples of pure Fe were treated by surface gas-phase RE permeation plus laser melting solidification (LMS). The microstructures were observed by Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS), meanwhile the corrosion resistance was investigated by electrochemical impedance spectroscopy (EIS) and anodic polarization. The results show that this treatment can remarkably improve the density and uniformity of microstructure, and enhance corrosion resistance of the pure Fe surface.

  12. THE INFLUENCE OF THE CURRENCIES RATE ON THE COUNTRY’S ECONOMICS

    Directory of Open Access Journals (Sweden)

    Saprunova E. A.

    2015-06-01

    Full Text Available The main aspects of the financial market influencing the country’s economy are considered in the article. In this field certain historical facts connected with the financial market are outlined. These facts show the USA economy influence on the world’s economics space determining the countries’ ability to resist financial expansion and insure their economies securities. Sustainable economic system capable to reserve the country’s sovereignty and to resist outer economic and political pressure is required for this activity. The basic aspects of the world currency system are given, the essence of some of them is revealed, some proposals are made that could stabilize the economies of the dollar-dependent countries. Besides, the article highlights the necessity to own gold reserve which means some extent secures to the country’s sovereignty. The agriculture investing perspective in case of inflation rate alignment is highlighted. The factors that influence the rate of the currency are given. Competitive ability of domestic products that have great influence on the country’s foreign trade is pointed out as the main factor in the relevance of the topic. To confirm some ideas of the article the opinions of scholars, known throughout the world as economists and philosophers are given. The topic of the welfare of the citizens of the country in periods of currency fluctuations has been considered and the recommendations for the improvement of their own position have been made

  13. Do Melt Inclusions Answer Big Questions?

    Science.gov (United States)

    Hofmann, A. W.; Sobolev, A. V.

    2009-12-01

    In a pioneering paper, Sobolev and Shimizu (1993) demonstrated the existence of ultra-depleted melt inclusions in olivine phenocrysts in MORB. They interpreted these as evidence for the preservation of parental melts formed by progressive near-fractional melting. Subsequently many cases have been described where melt inclusions from single basalt samples display enormous chemical and isotopic heterogeneity. The interpretation of these observations hinges critically on whether such melt inclusions can faithfully preserve primary or parental melt composition. If they do, melt inclusion data can truly answer big questions from small-scale observations. If they do not, they answer rather small questions. Favoring the second possibility, Danyushevsky et al. (2004) have suggested that much of the observed variability of highly incompatible trace elements in melt inclusions “may not represent geologically significant melts, but instead reflect localized, grain-scale reaction processes within the magmatic plumbing system.” We disagree and show that this mechanism cannot, for example, explain isotopic heterogeneity measured in several suites of melt inclusions, nor does it not account for the presence of ultra-depleted melts and "ghost" plagioclase signatures in other inclusions. More recently, Spandler et al. (2007) have suggested on the basis of experimental evidence that diffusion rates for REE in olivine are so rapid that parental melt compositions in melt inclusions are rapidly falsified by diffusional exchange with (evolved) host lava. We show that the very fact that extreme chemical and isotopic heterogeneities are routinely preserved in melt inclusions demonstrates that this conclusion is unwarranted, either because residence times of the olivine phenocrysts are much shorter than assumed by Spandler et al. or because the high experimental diffusion rates are caused by an unknown experimental artifact. Although there is no obvious flaw in design and execution of

  14. Influence of different combined severe shot peening and laser surface melting treatments on the fatigue performance of 20CrMnTi steel gear

    Energy Technology Data Exchange (ETDEWEB)

    Lv, You, E-mail: llvvyou@163.com.cn; Lei, Liqun; Sun, Lina

    2016-03-21

    In this paper, the effect of severe shot peening combined with laser melting (LSMSSP for short) on the fatigue resistance of 20CrMiTi steel gears is investigated in comparison with the effect of traditional shot peening on the fatigue resistance of the laser surface melted (LSMTSP for short) 20CrMiTi steel gear. The surface characteristics of the gear have been analyzed by a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). The Forschungsstelle für Zahnräder und Getriebebau (FZG) back-to-back spur gear test rig was used for fatigue experiments. Experimental results showed that the residual stresses, full width at half maximum (FWHM), microhardness and retained austenite of the LSMSSP gears and LSMTSP gear were entirely different. Although the LSMSSP gears had higher surface roughness than the LSMTSP gear, the LSMSSP gears still had better fatigue resistance than the LSMTSP gear and laser surface melted gear. The nanocrystallized surface layer on the gear tooth flank created by severe shot peening might be a very important factor for improving the fatigue property of the LSMSSP gears.

  15. INFLUENCE OF DOSE RATE ON THE CELLULAR RESPONSE TO LOW- AND HIGH-LET RADIATIONS

    Directory of Open Access Journals (Sweden)

    Anne-Sophie eWozny

    2016-03-01

    Full Text Available Nowadays, head and neck squamous cell carcinoma (HNSCC treatment failure is mostly explained by loco-regional progression or intrinsic radioresistance. Radiotherapy has recently evolved with the emergence of heavy ion radiations or new fractionation schemes of photon therapy which modify the dose-rate of treatment delivery. The aim of the present study was then to evaluate the in vitro influence of a dose rate variation during conventional radiotherapy or carbon ion hadrontherapy treatment in order to improve the therapeutic care of patient. In this regard, two HNSCC cell lines were irradiated with photons or 72MeV/n carbon ions at a dose rate of 0.5, 2 or 10Gy/min.For both radiosensitive and radioresistant cells, the change in dose rate significantly affected cell survival in response to photon exposure, this variation of radiosensitivity was associated to the number of initial and residual DNA double-strand breaks. By contrast, the dose rate change did not affect neither cell survival nor the residual DNA double-strand breaks after carbon ion irradiation. As a result, the Relative Biological Efficiency at 10% survival increased when the dose rate decreased.In conclusion, in the radiotherapy treatment of HNSCC, it is advised to remain very careful when modifying the classical schemes towards altered-fractionation. At the opposite, as the dose rate does not seem to have any effects after carbon ion exposure, there is less need to adapt hadrontherapy treatment planning during active system irradiation

  16. Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus).

    Science.gov (United States)

    French, Susannah S; González-Suárez, Manuela; Young, Julie K; Durham, Susan; Gerber, Leah R

    2011-03-16

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations.

  17. Influence of heat transfer rates on pressurization of liquid/slush hydrogen propellant tanks

    Science.gov (United States)

    Sasmal, G. P.; Hochstein, J. I.; Hardy, T. L.

    1993-01-01

    A multi-dimensional computational model of the pressurization process in liquid/slush hydrogen tank is developed and used to study the influence of heat flux rates at the ullage boundaries on the process. The new model computes these rates and performs an energy balance for the tank wall whereas previous multi-dimensional models required a priori specification of the boundary heat flux rates. Analyses of both liquid hydrogen and slush hydrogen pressurization were performed to expose differences between the two processes. Graphical displays are presented to establish the dependence of pressurization time, pressurant mass required, and other parameters of interest on ullage boundary heat flux rates and pressurant mass flow rate. Detailed velocity fields and temperature distributions are presented for selected cases to further illuminate the details of the pressurization process. It is demonstrated that ullage boundary heat flux rates do significantly effect the pressurization process and that minimizing heat loss from the ullage and maximizing pressurant flow rate minimizes the mass of pressurant gas required to pressurize the tank. It is further demonstrated that proper dimensionless scaling of pressure and time permit all the pressure histories examined during this study to be displayed as a single curve.

  18. Influence of Dose Rate on the Cellular Response to Low- and High-LET Radiations.

    Science.gov (United States)

    Wozny, Anne-Sophie; Alphonse, Gersende; Battiston-Montagne, Priscillia; Simonet, Stéphanie; Poncet, Delphine; Testa, Etienne; Guy, Jean-Baptiste; Rancoule, Chloé; Magné, Nicolas; Beuve, Michael; Rodriguez-Lafrasse, Claire

    2016-01-01

    Nowadays, head and neck squamous cell carcinoma (HNSCC) treatment failure is mostly explained by locoregional progression or intrinsic radioresistance. Radiotherapy (RT) has recently evolved with the emergence of heavy ion radiations or new fractionation schemes of photon therapy, which modify the dose rate of treatment delivery. The aim of the present study was then to evaluate the in vitro influence of a dose rate variation during conventional RT or carbon ion hadrontherapy treatment in order to improve the therapeutic care of patient. In this regard, two HNSCC cell lines were irradiated with photons or 72 MeV/n carbon ions at a dose rate of 0.5, 2, or 10 Gy/min. For both radiosensitive and radioresistant cells, the change in dose rate significantly affected cell survival in response to photon exposure. This variation of radiosensitivity was associated with the number of initial and residual DNA double-strand breaks (DSBs). By contrast, the dose rate change did not affect neither cell survival nor the residual DNA DSBs after carbon ion irradiation. As a result, the relative biological efficiency at 10% survival increased when the dose rate decreased. In conclusion, in the RT treatment of HNSCC, it is advised to remain very careful when modifying the classical schemes toward altered fractionation. At the opposite, as the dose rate does not seem to have any effects after carbon ion exposure, there is less need to adapt hadrontherapy treatment planning during active system irradiation.

  19. Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus.

    Directory of Open Access Journals (Sweden)

    Susannah S French

    Full Text Available The environment is currently undergoing changes at both global (e.g., climate change and local (e.g., tourism, pollution, habitat modification scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups for California sea lions (Zalophus californianus in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources. Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations.

  20. Influenza Vaccination Coverage Rate for Medical Staff: Influence of Hospital-Based Vaccination Campaign.

    Science.gov (United States)

    Zielonka, T M; Szymańczak, M; Jakubiak, J; Nitsch-Osuch, A; Życińska, K

    2016-01-01

    Despite intensive recommendations, influenza vaccination rate in medical staff in Poland ranges from about 20 % in physicians to 10 % in nurses. The objective of this work was to assess the influence of hospital influenza vaccination campaign directed toward health care workers, combined with dispensing free of charge vaccine, on vaccination rate. The campaign was conducted by the Hospital Infection Control Team of the Czerniakowski Hospital in Warsaw, Poland, separately for physicians, nurses, and physiotherapists. Overall, 37 % of medical staff were vaccinated, including 55 % of physicians and 21 % of nurses. Concerning physicians, the greatest vaccination rate was in the orthopedic (80 %) and ophthalmology units (73 %), whereas the lowest rate was in the intensive care (22 %) and neurology units (20 %). Concerning nurses, the greatest vaccination rate was in those working in the outpatient (40 %) and emergency units (29 %), whereas the lowest rate was in the ophthalmology (6 %) and surgery units (11 %). We conclude that the professional knowledge campaign combined with the incentive of free of charge vaccine substantially raises the vaccination rate among medical staff.

  1. Acute short-term mental stress does not influence salivary flow rate dynamics.

    Directory of Open Access Journals (Sweden)

    Ella A Naumova

    Full Text Available BACKGROUND: Results of studies that address the influence of stress on salivary flow rate and composition are controversial. The aim of this study was to reveal the influence of stress vulnerability and different phases of stress reactivity on the unstimulated and stimulated salivary flow rate. We examined that acute mental stress does not change the salivary flow rate. In addition, we also examined the salivary cortisol and protein level in relation to acute mental stress stimuli. METHODS: Saliva of male subjects was collected for five minutes before, immediately, 10, 30 and 120 min after toothbrushing. Before toothbrushing, the subjects were exposed to acute stress in the form of a 2 min public speech. Salivary flow rate and total protein was measured. The physiological stress marker cortisol was analyzed using enzyme-linked immunosorbent assay. To determine the subjects' psychological stress reaction, the State-Trait-Anxiety Inventory State questionnaire (STAI data were obtained. The subjects were divided into stress subgroup (S1 (psychological reactivity, stress subgroup (S2 (psychological and physiological reactivity and a control group. The area under the curve for salivarycortisol concentration and STAI-State scores were calculated. All data underwent statistical analysis using one-way analysis of variance. RESULTS: Immediately after stress exposure, all participants exhibited a psychological stress reaction. Stress exposure did not change the salivary flow rate. Only 69% of the subjects continued to display a physiological stress reaction 20 minutes after the public talk. There was no significant change in the salivary flow rate during the psychological and the physiological stress reaction phases relative to the baseline. CONCLUSIONS: Acute stress has no impact on the salivary flow rate; however, there may be other responses through salivary proteins that are increased with the acute stress stimuli. Future studies are needed to examine

  2. Ice-shelf melting around Antarctica

    National Research Council Canada - National Science Library

    Rignot, E; Jacobs, S; Mouginot, J; Scheuchl, B

    2013-01-01

    We compare the volume flux divergence of Antarctic ice shelves in 2007 and 2008 with 1979 to 2010 surface accumulation and 2003 to 2008 thinning to determine their rates of melting and mass balance...

  3. A Constitutive Model for Superelastic Shape Memory Alloys Considering the Influence of Strain Rate

    Directory of Open Access Journals (Sweden)

    Hui Qian

    2013-01-01

    Full Text Available Shape memory alloys (SMAs are a relatively new class of functional materials, exhibiting special thermomechanical behaviors, such as shape memory effect and superelasticity, which enable their applications in seismic engineering as energy dissipation devices. This paper investigates the properties of superelastic NiTi shape memory alloys, emphasizing the influence of strain rate on superelastic behavior under various strain amplitudes by cyclic tensile tests. A novel constitutive equation based on Graesser and Cozzarelli’s model is proposed to describe the strain-rate-dependent hysteretic behavior of superelastic SMAs at different strain levels. A stress variable including the influence of strain rate is introduced into Graesser and Cozzarelli’s model. To verify the effectiveness of the proposed constitutive equation, experiments on superelastic NiTi wires with different strain rates and strain levels are conducted. Numerical simulation results based on the proposed constitutive equation and experimental results are in good agreement. The findings in this paper will assist the future design of superelastic SMA-based energy dissipation devices for seismic protection of structures.

  4. The influence of the repetition rate on the nanosecond pulsed pin-to-pin microdischarges

    Science.gov (United States)

    Huang, Bang-Dou; Takashima, Keisuke; Zhu, Xi-Ming; Pu, Yi-Kang

    2014-10-01

    The effect of repetition rate on a nanosecond atmospheric pressure discharge is investigated. The discharge is generated between two pins in a mixture of Ne and Ar. The voltage, current, power waveforms and the temporally and spatially resolved electron density and an ‘effective’ electron temperature are measured, with a pulse interval between 1.5 and 200 µs. It is found that not only does the repetition rate have a strong influence on the breakdown voltage and the peak discharge power, but it can also affect the rise rate of the volume averaged electron density and its peak value. Temporally and spatially resolved measurement of the electron density and the effective electron temperature show that the spatial distributions of both quantities are also influenced by the repetition rate. In the initial discharge period of all cases, the sharp rise of the electron density correlates with the drastic drop of the effective electron temperature. It is suggested that the residual charges have a strong impact on the axial distribution of the electric field and energetic electrons between the electrodes during the breakdown period, as illustrated by a simple sheath model.

  5. Influence of arterial geometry on a model for growth rate of atheromas

    Energy Technology Data Exchange (ETDEWEB)

    Gessaghi, Valeria C [Facultad de Ingenieria, Universidad Nacional de La Pampa, General Pico, La Pampa (Argentina); Raschi, Marcelo A [Facultad de Ingenieria y Ciencias Exactas y Centro de Estudios Avanzados, Universidad Argentina de la Empresa, Ciudad Autonoma de Buenos Aires (Argentina); Larreteguy, Axel E [Facultad de Ingenieria y Ciencias Exactas y Centro de Estudios Avanzados, Universidad Argentina de la Empresa, Ciudad Autonoma de Buenos Aires (Argentina); Perazzo, Carlos A [Facultad de Ingenieria y Ciencias Exactas y Naturales, Universidad de Favaloro, Ciudad Autonoma de Buenos Aires, Argentina y CONICET (Argentina)

    2007-11-15

    Atherosclerosis is a disease that affects medium and large size arteries and it can partially or totally obstruct blood flow through them. The lack of blood supply to the heart or the brain can cause an infarct or a stroke with fatal consequences or permanent effects. This disease involves the proliferation of cells and the accumulation of fat, cholesterol, cell debris, calcium and other substances in the artery wall. Such accumulation results in the formation of atherosclerotic plaques called atheromas, which may cause the obstruction of the blood flow. Cardiovascular diseases, among which atherosclerosis is the most frequent, are the first cause of death in developed countries. The published works in the subject suggest that hemodynamic forces on arterial walls have influence on the localization, initial development and growth rate of atheromas. This paper presents a model for this growth rate, and explores the influence of the bifurcation angle on the blood flow patterns and on the predictions of the model in a simplified carotid artery. The choice of the carotid bifurcation as the subject for this study obeys the fact that atheromas in this artery are often responsible for strokes. Our model predicts a larger initial growth rate in the external walls of the bifurcation and smaller growth area and lower growth rates as the bifurcation angle is increased. The reason for this seems to be the appearance of helical flow patterns as the angle is increased.

  6. Melt electrospinning vs. solution electrospinning: A comparative study of drug-loaded poly (ε-caprolactone) fibres.

    Science.gov (United States)

    Lian, He; Meng, Zhaoxu

    2017-05-01

    Curcumin-loaded poly (ε-caprolactone) (PCL) fibres prepared by melt and solution electrospinning methods were both fabricated to investigate their difference in characterization and drug release behaviour. The increasing curcumin content did not influence the morphologies of melt electrospun fibre, but enhanced the range of diameter distribution of solution electrospun fibre owing to the curcumin aggregates in the spinning solution which disturbed the stability of jet. Moreover, a large amount of curcumin with amorphous state could be loaded in the melt electrospun fibre. Whereas the limited solubility of curcumin in the solvent led to the drug aggregates dispersing within the solution electrospun fibre. In addition, the melt electrospun fibres had low drug release rate without burst release on the profiles due to the high crystallinity in the fibre, but high drug release rate and burst release occurred on the release profiles of the solution electrospun fibres because of their low crystallinity, porous structure and roughness surface.

  7. Production of high melt strength polypropylene by gamma irradiation

    Science.gov (United States)

    Lugão, A. B.; Artel, B. W. H.; Yoshiga, A.; Lima, L. F. C. P.; Parra, D. F.; Bueno, J. R.; Liberman, S.; Farrah, M.; Terçariol, W. R.; Otaguro, H.

    2007-11-01

    High melt strength polypropylene (HMS-PP) has been recently developed and introduced in the market by the major international producers of polypropylene. Therefore, BRASKEM, the leading Brazilian PP producer, together with EMBRARAD, the leading Brazilian gamma irradiator, and the IPEN (Institute of Nuclear Energy and Research) worked to develop a national technology for the production of HMS-PP. One of the effective approaches to improve melt strength and extensibility is to add chain branches onto polypropylene backbone using gamma radiation. Branching and grafting result from the radical combinations during irradiation process. Crosslinking and main chain scission in the polymer structure are also obtained during this process. In this work, gamma irradiation technique was used to induce chemical changes in commercial polypropylene with two different monomers, Tri-allyl-isocyanurate (TAIC) and Tri-methylolpropane-trimethacrylate (TMPTMA), with concentration ranging from 1.5 to 5.0 mmol/100 g of polypropylene. These samples were irradiated with a 60Co source at dose of 20 kGy. It used two different methods of HMS-PP processing. The crosslinking of modified polymers was studied by measuring gel content melt flow rate and rheological properties like melt strength and drawability. It was observed that the reaction method and the monomer type have influenced the properties. However, the concentration variation of monomer has no effect.

  8. Influence of the temperature on the tension behaviour of EUROFER97 alloy at high strain rate

    Directory of Open Access Journals (Sweden)

    Cadoni Ezio

    2015-01-01

    Full Text Available This paper presents an experimental investigation on the influence of the temperature on the reduced activation steel Eurofer97 under uniaxial tensile loads at high strain rate. Round undamaged specimens of this material having gauge length 5 mm, diameter 3 mm, were tested in universal machine to obtain its stress-strain relation under quasi-static condition (0.001s−1, and in modified Hopkinson bar to study its mechanical behaviour at high strain rates (300 s−1, 1000 s−1 respectively. The tests at high strain rate were carried out at 450 °C and at nitrogen temperature. Finally, the parameters of the Zerilli-Armstrong constitutive material relationship were obtained.

  9. Additional experimental evidence for a solar influence on nuclear decay rates

    CERN Document Server

    Jenkins, Jere H; Blue, Thomas E; Fischbach, Ephraim; Javorsek, Daniel; Kauffman, Andrew C; Mundy, Daniel W; Sturrock, Peter A; Talnagi, Joseph W

    2012-01-01

    Additional experimental evidence is presented in support of the recent hypothesis that a possible solar influence could explain fluctuations observed in the measured decay rates of some isotopes. These data were obtained during routine weekly calibrations of an instrument used for radiological safety at The Ohio State University Research Reactor using Cl-36. The detector system used was based on a Geiger-Mueller gas detector, which is a robust detector system with very low susceptibility to environmental changes. A clear annual variation is evident in the data, with a maximum relative count rate observed in January/February, and a minimum relative count rate observed in July/August, for seven successive years from July 2005 to June 2011. This annual variation is not likely to have arisen from changes in the detector surroundings, as we show here.

  10. The Influence of Mobility Rate on Spiral Waves in Spatial Rock-Paper-Scissors Games

    CERN Document Server

    Mobilia, Mauro; Szczesny, Bartosz

    2016-01-01

    We consider a two-dimensional model of three species in rock-paper-scissors competition and study the self-organisation of the population into fascinating spiraling patterns. Within our individual-based metapopulation formulation, the population composition changes due to cyclic dominance (dominance-removal and dominance-replacement), mutations, and pair-exchange of neighboring individuals. Here, we study the influence of mobility on the emerging patterns and investigate when the pair-exchange rate is responsible for spiral waves to become elusive in stochastic lattice simulations. In particular, we show that the spiral waves predicted by the system's deterministic partial equations are found in lattice simulations only within a finite range of the mobility rate. We also report that in the absence of mutations and dominance-replacement, the resulting spiraling patterns are subject to convective instability and far-field breakup at low mobility rate. Possible applications of these resolution and far-field brea...

  11. The Influence of Reaction Rates on the Final p-Abundances

    CERN Document Server

    Rapp, W; Schatz, H; Käppeler, F K

    2004-01-01

    The astrophysical p-process is responsible for the origin of the proton rich nuclei,which are heavier than iron. A huge network involving thousands of reaction rates is necessary to calculate the final p-abundances. But not all rates included in the network have a strong influence on the p-nuclei abundances. The p-process was investigated using a full nuclear reaction network for a type II supernovae explosion when the shock front passes through the O/Ne layer. Calculations were done with a multi-layer model adopting the seed of a pre-explosion evolution of a 25 mass star. In extensive simulations we investigated the impact of single reaction rates on the final p-abundances. The results are important for the strategy of future experiments in this field.

  12. Influence of quench rate and microstructure on bendability of AA6016 aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Castany, P., E-mail: philippe.castany@insa-rennes.fr [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Diologent, F.; Rossoll, A. [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Despois, J.-F.; Bezencon, C. [Novelis Switzerland SA, 3960 Sierre (Switzerland); Mortensen, A., E-mail: andreas.mortensen@epfl.ch [Laboratoire de Metallurgie Mecanique, Institut des Materiaux, Station 12, Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland)

    2013-01-01

    The influence of the quench rate after solution treatment on the bendability of AA6016 aluminum alloy sheets was investigated. Crack initiation during bending tests is found to be independent of quench rate whereas crack propagation is decreased after rapid quenching. A quantitative analysis of microstructures was carried out by transmission electron microscopy, focusing on grain boundary precipitates to correlate bending properties with microstructure. Crack initiation occurs by voiding at large micron-size intermetallic AlFeSi particles in shear bands, as previously proposed in the literature. Rapid quenching promotes the formation along grain boundaries of spherical Mg{sub 2}Si precipitates to the detriment of elongated Si precipitates that dominate after slow cooling. These Si grain boundary precipitates affect micro-voiding processes that drive crack propagation, which explains the observed dependence of the extent of cracking on quench rate. The grain boundary precipitate density has on the other hand no effect on crack initiation or propagation.

  13. Influence of lead Inorganic Compounds on Combustion Rate of Double Base Rocket Propellants

    Directory of Open Access Journals (Sweden)

    V. B. Pillai

    1982-04-01

    Full Text Available The influence of lead nitrate, red lead, lead chromate, lead floride and lead carbonate on the combustion behaviour of double base propellants in the pressure range-35-140kg/cm /sup 2/ was studied. While all these compounds increased burning rates in lower pressure range (35-60 kg/cm/sup 2/ and higher pressure range (120-140 kg/cm/sup 2/, only lead chromate and lead fluoride were effective in the intermediate pressure range of 60-105 kg/cm/sup 2/. None of these compounds were effective as platonizer, except lead fluoride, which lowered n value to 0.34 in the lower pressure range. Addition of carbon black along with lead compounds raised burning rates further and reduced n values significantly in the higher pressure regins. A probable mechanism on the role of lead compounds studied has been suggested based on burning rate and DTA results.

  14. [Influence of physical workload patterns and breaks on heart rate recovery].

    Science.gov (United States)

    Kadoya, Manabu; Izumi, Hiroyuki; Kubota, Makoto; Yamashita, Tsuyoshi; Kumashiro, Masaharu

    2010-01-01

    It is necessary to try to achieve quick recovery from work strain by setting adequate breaks and shortening continuous working hours to prevent the accumulation of fatigue. However, there has been no research investigating the influence of the timing and lengths of breaks on individual aerobic capacities in recovery from work strain. In this study, we set three load patterns based on the length and timing of breaks: "no breaks", "one break" and "regular small breaks". We examined the differences of the heart rate variation in the recovery time after working considering the individual aerobic capacities (VO(2)max) of ten male subjects (mean age 22.3 +/- 1.7 yr) in the case of 50 W or 100 W workloads on a bicycle ergometer. When individual aerobic capacity was not considered, the "regular small breaks" condition led to the quickest recovery to the level of the resting heart rate at 50 W workload. Not all conditions showed heart rate recovery within 30 min at 100 W workload. On the other hand, when individual aerobic capacity was considered, the "regular small breaks" condition showed the quickest recovery to the level of the resting heart rate at 50 W workload in the low aerobic capacity group (VO(2)max mean 42.2 +/- 3.7 ml/kg/min). However, in the high aerobic capacity group (VO(2)max mean 54.5 +/- 4.1 ml/kg/min), the "regular small breaks" condition resulted in the quickest recovery of the level to the resting heart rate at 100W workload. Two-way repeated measures ANOVA was performed for the recovery time with respect to the rate of increase from resting heart rate to examine the influence on heart rate recovery of physical activity loads, workload patterns and individual fitness. Physical activity loads were strongly related to the increase from resting heart rate in recovery time, and workload patterns showed that the regular small breaks condition was related to the heart rate recovery in the high fitness subjects in the case of the exercise intensity of 100 W

  15. Modeling the influence of potassium content and heating rate on biomass pyrolysis

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Surup, Gerrit; Shapiro, Alexander

    2017-01-01

    This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing. The shrink......This study presents a combined kinetic and particle model that describes the effect of potassium and heating rate during the fast pyrolysis of woody and herbaceous biomass. The model calculates the mass loss rate, over a wide range of operating conditions relevant to suspension firing....... The shrinking particle model considers internal and external heat transfer limitations and incorporates catalytic effects of potassium on the product yields. Modeling parameters were tuned with experimentally determined char yields at high heating rates (>200 K s−1) using a wire mesh reactor, a single particle...... burner, and a drop tube reactor. The experimental data demonstrated that heating rate and potassium content have significant effects on the char yield. The importance of shrinkage on the devolatilization time becomes greater with increasing particle size, but showed little influence on the char yields....

  16. Influence of Seeding Rate on Weed Density in Soybean Planting System for Southeastern Coastal Plains

    Directory of Open Access Journals (Sweden)

    Pawel Wiatrak

    2011-01-01

    Full Text Available Problem statement: Increasing seeding rates may help decrease weed pressure in soybean [Glycine max (L. Merr.] wide row spacing. Approach: The objective of this study was to evaluate the influence of five glyphosate-resistant soybean Maturity Groups (MG (IV, V, VI, VII and VIII and six seeding rates (68,000,136,000, 204,000, 272,000, 340,000 and 408,000 seeds ha-1 on weed density under dryland conditions on the Southeastern coastal plain in 2007-2009. Results: Weed decrease with increasing seeding rate varied over years. Weed density was generally lower at higher seeding rates for most MG soybeans at 30 and 60 DAP, except MG IV and VIII at 30 DAP in 2007 and MG VI at 30 DAP in 2008. At 60 DAP, soybean leaf area index (LAI and normalized difference vegetation index (NDVI were greater with lower weed density. Conclusion: Additionally, negative correlations were observed between weed density and plant LAI/NDVI for all MG in 2008 and MG IV through VI in 2009. These results suggest that increased seeding rates may help decrease weed pressure and improve soybean growth at early growth stages. However the response of weed pressure to seeding rate may vary over years and depend on MG soybean.

  17. INFLUENCE OF MIMIC CARDIAC RATE ON HYDRODYNAMICS OF DIFFERENT MECHANICAL PROSTHETIC CARDIAC VALVES IN VITRO

    Institute of Scientific and Technical Information of China (English)

    Yin-ping Chu; Jin-lian Cheng; Ru-kun Chen; Yu-bo Fan; Fang Pu

    2005-01-01

    Objective To assess the influence of mimic cardiac rate on hydrodynamics of different mechanical prosthetic cardiac valves.Methods US-made CarboMedics bileaflet valve, China-made Jiuling bileaflet valve and C-L tilting disc valve were tested via a pulsatile flow simulator in the aortic position. Testing conditions were set at mimic cardiac rates of 55 bpm, 75 bpm, 100bpm with a constant mimic cardiac output of 4 L/min. The mean pressure differences (△P), leakage volumes (LEV) and closing volumes (CLV) across each valve, and effective orifice areas (EOA) were analyzed.Results Within physiological range, △p, LEV, and CLV decreased as mimic cardiac rate increased, with a large extent of variance. EOA increased along with an increase in mimic cardiac rate. It was a different response in terms of cardiac rate alteration for different types of mechanical prosthetic cardiac valves.Conclusion Mimic cardiac rate change affects hydrodynamics of mechanical prosthetic cardiac valves. Within physiological range, the hydrodynamic of prosthetic bileaflet valve is better than that of tilting disc valve.

  18. ESCIMO.spread – a spreadsheet-based point snow surface energy balance model to calculate hourly snow water equivalent and melt rates for historical and changing climate conditions

    Directory of Open Access Journals (Sweden)

    T. Marke

    2010-05-01

    Full Text Available This paper describes the spreadsheet-based point energy balance model ESCIMO.spread which simulates the energy and mass balance as well as melt rates of a snow surface. The model makes use of hourly recordings of temperature, precipitation, wind speed, relative humidity, global and longwave radiation. The effect of potential climate change on the seasonal evolution of the snow cover can be estimated by modifying the time series of observed temperature and precipitation by means of adjustable parameters. Model output is graphically visualized in hourly and daily diagrams. The results compare well with weekly measured snow water equivalent (SWE. The model is easily portable and adjustable, and runs particularly fast: hourly calculation of a one winter season is instantaneous on a standard computer. ESICMO.spread can be obtained from the authors on request (contact: ulrich.strasser@uni-graz.at.

  19. Does multimorbidity influence the occurrence rates of chronic conditions? A claims data based comparison of expected and observed prevalence rates.

    Directory of Open Access Journals (Sweden)

    Ingmar Schäfer

    Full Text Available OBJECTIVE: Multimorbidity is a complex phenomenon with an almost endless number of possible disease combinations with unclear implications. One important aspect in analyzing the clustering of diseases is to distinguish between random coexistence and statistical dependency. We developed a model to account for random coexistence based on stochastic distribution. We analyzed if the number of diseases of the patients influences the occurrence rates of chronic conditions. METHODS: We analyzed claims data of 121,389 persons aged 65+ using a list of 46 chronic conditions. Expected prevalences were simulated by drawing without replacement from all observed diseases using observed overall prevalences as initial probability weights. To determine if a disease occurs more or less frequently than expected by chance we calculated observed-minus-expected deltas for each disease. We defined clinical relevance as |delta| ≥ 5.0%. 18 conditions were excluded because of a prevalence < 5.0%. RESULTS: We found that (1 two chronic conditions (e.g. hypertension were more frequent than expected in patients with a low number of comorbidities; (2 four conditions (e.g. renal insufficiency were more frequent in patients with many comorbidities; (3 six conditions (e.g. cancer were less frequent with many comorbidities; and (4 16 conditions had an average course of prevalences. CONCLUSION: A growing extent of multimorbidity goes along with a rapid growth of prevalences. This is for the largest part merely a stochastic effect. If we account for this effect we find that only few diseases deviate from the expected prevalence curves. Causes for these deviations are discussed. Our approach also has methodological implications: Naive analyses of multimorbidity might easily be affected by bias, because the prevalence of all chronic conditions necessarily increases with a growing extent of multimorbidity. We should therefore always examine and discuss the stochastic interrelations

  20. DSC study on the undercooling of droplet solidification of metal melt

    Institute of Scientific and Technical Information of China (English)

    GUAN Wanbing; GAO Yulai; ZHAI Qijie; XU Kuangdi

    2005-01-01

    In this paper, the influence of cooling rate on the undercooling of droplet solidification of metal melt has been investigated by employing the differential scanning calorimetry (DSC) method. The effect of cooling rate on the undercooling as well as its change tendency is analyzed theoretically. It is shown that the undercooling degree increases whereas the change rate of undercooling decreases with increasing cooling rate. Moreover, the change tendency approaches zero when the cooling rate exceedingly increased, indicating that an extremum of undercooling exists with increasing cooling rate.

  1. Determination of ohmic/voltage drop and factors influencing anodic overvoltage of carbon anodes in Na3AlF6-Al2O3 based melts

    Institute of Scientific and Technical Information of China (English)

    李庆余; 李劼; 田忠良; 张刚

    2003-01-01

    Experimental technique has been inadequate to anodic overvoltage measurements in aluminum electrolysis. To determine its ohmic/voltage drop precisely, a current interruption technique was modified with a high frequency digital oscilloscope, current interrupters with fast switching time, an improved cell configuration and a simulation applied to the oscillating potential decay curve. The results show that the technique can give good reproducibility for overvoltage studies. A substantial increase of anodic overvoltage is observed with graphite powder addition, metallic aluminum addition and CO bubbling in the melts.

  2. Real time heart rate variability assessment from Android smartphone camera photoplethysmography: Postural and device influences.

    Science.gov (United States)

    Guede-Fernandez, F; Ferrer-Mileo, V; Ramos-Castro, J; Fernandez-Chimeno, M; Garcia-Gonzalez, M A

    2015-01-01

    The aim of this paper is to present a smartphone based system for real-time pulse-to-pulse (PP) interval time series acquisition by frame-to-frame camera image processing. The developed smartphone application acquires image frames from built-in rear-camera at the maximum available rate (30 Hz) and the smartphone GPU has been used by Renderscript API for high performance frame-by-frame image acquisition and computing in order to obtain PPG signal and PP interval time series. The relative error of mean heart rate is negligible. In addition, measurement posture and the employed smartphone model influences on the beat-to-beat error measurement of heart rate and HRV indices have been analyzed. Then, the standard deviation of the beat-to-beat error (SDE) was 7.81 ± 3.81 ms in the worst case. Furthermore, in supine measurement posture, significant device influence on the SDE has been found and the SDE is lower with Samsung S5 than Motorola X. This study can be applied to analyze the reliability of different smartphone models for HRV assessment from real-time Android camera frames processing.

  3. Influence of Prolonged Spaceflight on Heart Rate and Oxygen Uptake Kinetics

    Science.gov (United States)

    Hoffmann, U.; Moore, A.; Drescher, U.

    2013-02-01

    During prolonged spaceflight, physical training is used to minimize cardiovascular deconditioning. Measurement of the kinetics of cardiorespiratory parameters, in particular the kinetic analysis of heart rate, respiratory and muscular oxygen uptake, provides useful information with regard to the efficiency and regulation of the cardiorespiratory system. Practically, oxygen uptake kinetics can only be measured at the lung site (V’O2 resp). The dynamics of V’O2 resp, however, is not identical with the dynamics at the site of interest: skeletal muscle. Eight Astronauts were tested pre- and post-flight using pseudo random binary workload changes between 30 and 80 W. Their kinetic responses of heart rate, respiratory as well as muscular V’O2 kinetics were estimated by using time-series analysis. Statistical analysis revealed that the kinetic responses of respiratory as well as muscular V’O2 kinetics are slowed post-flight than pre-flight. Heart rate seems not to be influenced following flight. The influence of other factors (e. g. astronauts’ exercise training) may impact these parameters and is an area for future studies.

  4. Influence of Production System, Sex and Litter Size on Growth Rates in Turcana Lambs

    Directory of Open Access Journals (Sweden)

    Dinu Gavojdian

    2013-10-01

    Full Text Available Lamb meat production has become the main source of income in the Romanian sheep farming industry, representing over 66% of the total returns. Turcana breed represents over 70% of the national flock, and 92% of the sheep bred in western Romania. However, meat production potential and growth rates of the breed are low, and thus strategies to improve performance of the Turcana lambs need to be identified. Aim of the current research was to evaluate the effects that sex and litter size have on the growth rates of lambs from Turcana breed under extensive and semi-intensive production systems. Weaning weight was significantly (p≤0.001 influenced by the production system, with lambs reared extensively registering a average body weights of 18.23±0.094 kg at the age of 90 days, while the semi-intensively reared lambs registered an average weight of 20.19±0.082 kg. It was concluded that all three factors taken into study significantly influence growth rates in Turcana lambs and that weight of the lamb(s at the age of 28 days should be included as a selection trait within the Turcana breed genetic improvement plan.

  5. Influence of cooling rate on interlaminar fracture properties of unidirectional commingled CF/PEEK composites

    Science.gov (United States)

    Beehag, Andrew; Ye, Lin

    1995-05-01

    The influence of cooling rates on the mechanical property profile (transverse flexure properties and modes-I and -II interlaminar fracture toughness) has been investigated for unidirectional commingled CF/PEEK composites. A laboratory hot press with a steel mould was used to process the composites at 400°C for 60 min, at an applied pressure of 1 MPa. Cooling rates from fast (quenching in oil) to slow (hot press cooling) were achieved at ambient pressure. The results indicate that different matrix morphology was found at different cooling conditions, although deconsolidation occurred in the CF/PEEK composites during cooling. When the cooling rate was shifted from slow to fast, consolidation quality of the CF/PEEK composites was improved. The resulting effect of the consolidation quality and cooling rates on the mechanical property profile of commingled CF/PEEK composites is presented. It was found that the effect of the cooling rate on the mechanical property profile of the commingled CF/PEEK composites could not be isolated from the consolidation quality.

  6. Preferred Barefoot Step Frequency is Influenced by Factors Beyond Minimizing Metabolic Rate

    Science.gov (United States)

    Yandell, Matthew B.; Zelik, Karl E.

    2016-03-01

    Humans tend to increase their step frequency in barefoot walking, as compared to shod walking at the same speed. Based on prior studies and the energy minimization hypothesis we predicted that people make this adjustment to minimize metabolic cost. We performed an experiment quantifying barefoot walking metabolic rate at different step frequencies, specifically comparing preferred barefoot to preferred shod step frequency. We found that subjects increased their preferred frequency when walking barefoot at 1.4 m/s (~123 vs. ~117 steps/min shod, P = 2e-5). However, average barefoot walking metabolic rates at the preferred barefoot and shod step frequencies were not significantly different (P = 0.40). Instead, we observed subject-specific trends: five subjects consistently reduced (‑8% average), and three subjects consistently increased (+10% average) their metabolic rate at preferred barefoot vs. preferred shod frequency. Thus, it does not appear that people ubiquitously select a barefoot step frequency that minimizes metabolic rate. We concluded that preferred barefoot step frequency is influenced by factors beyond minimizing metabolic rate, such as shoe properties and/or perceived comfort. Our results highlight the subject-specific nature of locomotor adaptations and how averaging data across subjects may obscure meaningful trends. Alternative experimental designs may be needed to better understand individual adaptations.

  7. Influence of composition on rate of polymerization contraction of light-curing resin composites.

    Science.gov (United States)

    Asmussen, Erik; Peutzfeldt, Anne

    2002-06-01

    A slow contraction may result in reduced gap formation when a restorative resin polymerizes in a dental cavity. It was the aim in the present work to investigate the rate of contraction in relation to composition of experimental light-curing resin composites. The monomer of the resin composites consisted of mixtures of BisGMA, TEGDMA, and in one series HEMA. The resins contained varying amounts of initiators, co-initiators, and inhibitor, and were made composite by adding a silanized glass filler to a content of 74% by weight of the composite paste. The polymerization contraction up to 120 sec was determined by means of the bonded-disk method. Within the ranges studied, the concentration of initiator and co-initiator in the monomer mixture had only an insignificant influence on rate of polymerization. In comparison to camphorquinone, the initiators 1-phenyl-1,2-propanedione and benzil reduced the rate of polymerization without affecting the final contraction. In comparison to N,N-dimethyl-p-aminobenzoic acid ethyl ester, N,N-cyanoethyl methylaniline was as effective, while N,N-diethanol-p-toluidine was less effective as co-initiator. A relatively high content of the inhibitor methoxyhydroquinone reduced the initial rate but not the final polymerization contraction. The rate of polymerization increased with the level of HEMA and TEGDMA in the monomer mixture. It was concluded that intrinsic slow cure may be obtained with certain compositions of resin composites without impairing the final extent of polymerization.

  8. Changes in induction methods have not influenced cesarean section rates among women with induced labor.

    Science.gov (United States)

    Dögl, Malin; Vanky, Eszter; Heimstad, Runa

    2016-01-01

    Induction of labor has become more common in most countries during the last decade. We have compared methods and routines of labor induction as practiced in Norway in 2003 and 2013, and surveyed practices with regard to induction of labor without a medical indication in 2013. A telephone interview with all delivery units in Norway was conducted in 2003. Data on preferred induction methods, use of prostaglandin, dosages, dose intervals and routes of administration were collected. In 2013, the same questionnaire was used, with additional questions on induction of labor without a medical indication. Data on overall cesarean section and induction rates were obtained from the Medical Birth Registry of Norway. From 2003 to 2013 the induction rate increased by 62% and the cesarean section rate by 6%. The cesarean section rate in women with induced labor remained stable at 17.1 and 17.4%, respectively. In 2003, 31 of 43 hospitals used dinoprostone for cervical ripening and induction. In 2013, 34 of 39 hospitals used misoprostol. A cervical balloon was used in three of 43 hospitals in 2003 compared with 31 of 39 in 2013. All but one hospital induced labor without a strict medical indication in 2013. The preferred methods for induction of labor changed within a decade to the use of misoprostol and cervical balloon. Induction of labor without strict medical indications is widely practiced. The changed induction methods have not influenced the cesarean section rates in women with induced labors. © 2015 Nordic Federation of Societies of Obstetrics and Gynecology.

  9. Study of influence of exchange rate change on the supply and demand of energy

    Energy Technology Data Exchange (ETDEWEB)

    Sohn, Y.H.; Shin, D.C. [Korea Energy Economics Institute, Euiwang (Korea, Republic of)

    1997-08-01

    The change of relative prices of trading goods and non-trading goods due to appreciation or depreciation of real exchange rates influences industrial structure and trading infrastructure by changing output, consumption, import and export, and prices of domestic economy. Considering that energy is used as intermediate input of all industrial sectors as well as in final consumption in the Korean economy which lacks energy resources and relies on imported energy resources, I believe that assessing the concrete effects of the real exchange rate change onto the energy industry must be a very important item in establishing effective energy policy. In this thesis, I measure the elasticity of the exchange rate as endogenous factors related to the energy industry using a CGE model that breaks down the energy industry. One (1) % depreciation of real exchange rate increases the domestic sales prices of all energy industry sectors, and the price increase ratios of petroleum and coal products are calculated as the highest among these. Petroleum and coal products show the highest price increase ratios while both the output and export decrease. On the other hand, depreciation increases the domestic sales prices of power generation, city gas, and heating sectors, but it is found to increase the output apart from petroleum and coal products. Depreciation of the real exchange rate is found to change the composition of the energy industry from petroleum and coal products to power generation, city gas, and heating sectors. 11 refs., 1 fig., 6 tabs.

  10. Does time of day influence cancer detection and recall rates in mammography?

    Science.gov (United States)

    Stinton, Chris; Jenkinson, David; Adekanmbi, Victor; Clarke, Aileen; Taylor-Phillips, Sian

    2017-03-01

    Background: The interpretation of screening mammograms is influenced by factors such as reader experience and their annual interpretative volume. There is some evidence that time of day can also have an effect, with better diagnostic accuracy for readings conducted early in the day. This is not a consistent finding, however. The aim of our study is to provide further evidence on whether there is an effect of time of day on recall- and breast cancer detection rates. Method: We analysed breast screening data from 222,577 women from the Midlands of England. Data were split into three eight hour periods: 0900-1700, 1700-0100, 0100-0900. Differences in recall- and cancer detection rates were analysed using multilevel logistic regression models. Results: Recall rates were lowest for mammograms read between the 1700-0100 time period. Cancer detection rates were lowest during the 0100-0900 time period. Conclusions: Our findings suggest that there are fluctuations in recall- and cancer detection rates over the course of the day.

  11. Higher speciation and lower extinction rates influence mammal diversity gradients in Asia.

    Science.gov (United States)

    Tamma, Krishnapriya; Ramakrishnan, Uma

    2015-02-04

    Little is known about the patterns and correlates of mammal diversity gradients in Asia. In this study, we examine patterns of species distributions and phylogenetic diversity in Asia and investigate if the observed diversity patterns are associated with differences in diversification rates between the tropical and non-tropical regions. We used species distribution maps and phylogenetic trees to generate species and phylogenetic diversity measures for 1° × 1° cells across mainland Asia. We constructed lineage-through-time plots and estimated diversification shift-times to examine the temporal patterns of diversifications across orders. Finally, we tested if the observed gradients in Asia could be associated with geographical differences in diversification rates across the tropical and non-tropical biomes. We estimated speciation, extinction and dispersal rates across these two regions for mammals, both globally and for Asian mammals. Our results demonstrate strong latitudinal and longitudinal gradients of species and phylogenetic diversity with Southeast Asia and the Himalayas showing highest diversity. Importantly, our results demonstrate that differences in diversification (speciation, extinction and dispersal) rates between the tropical and the non-tropical biomes influence the observed diversity gradients globally and in Asia. For the first time, we demonstrate that Asian tropics act as both cradles and museums of mammalian diversity. Temporal and spatial variation in diversification rates across different lineages of mammals is an important correlate of species diversity gradients observed in Asia.

  12. Influence of regulatory measures on the rate of spontaneous adverse drug reaction reporting in Italy.

    Science.gov (United States)

    Motola, Domenico; Vargiu, Antonio; Leone, Roberto; Conforti, Anita; Moretti, Ugo; Vaccheri, Alberto; Velo, Giampaolo; Montanaro, Nicola

    2008-01-01

    The reporting of adverse drug reactions (ADRs) is the mainstay of post-marketing surveillance systems. Under-reporting and selective reporting are considered the main limitations of a spontaneous reporting-based pharmacovigilance system. However, excessive reporting induced by external events may also impair signal detection by increasing the noise level. The aim of this study was to examine the influence of regulatory measures and other external factors on the rate of ADR reporting in Italy, focusing on four situations occurring in the last 10 years: ACE inhibitor-induced cough; HMG-CoA reductase inhibitors ('statins') and rhabdomyolysis; nimesulide and hepatic toxicity; and cyclo-oxygenase (COX)-2 selective inhibitors ('coxibs') and increase in cardiovascular risk. The study was based on data from spontaneous reporting in six Italian regions collected from January 1995 to December 2005. We analysed a 10-year period as a reasonable time interval around the four situations of interest, highlighting the influence of regulatory measures on the rate of ADR reporting (number of reports per million inhabitants). Chi-squared tests were used to assess the statistical significance of any changes in ADR reporting. Drug sales data were also studied to examine possible changes in drug use. Sales data were expressed as daily defined dose per 1000 inhabitants per day. ACE inhibitors: a 5-fold increase in the reporting rate of ACE inhibitor-induced cough was observed in 1998 and 1999 following a restriction on reimbursement for angiotensin receptor blockers introduced in 1998 and removed at the end of 1999. Statins: after the withdrawal of cerivastatin in 2001, the ADR reporting rate increased more than 4-fold, with musculoskeletal ADRs representing about 60% of all the ADRs reported in that year, and progressively decreased in the following years. Nimesulide: an increase in hepatic ADR reporting was observed after withdrawal of the drug from the Finnish and Spanish markets in

  13. Influence of Modelling Options in RELAP5/SCDAPSIM and MAAP4 Computer Codes on Core Melt Progression and Reactor Pressure Vessel Integrity

    Directory of Open Access Journals (Sweden)

    Siniša Šadek

    2010-01-01

    Full Text Available RELAP5/SCDAPSIM and MAAP4 are two widely used severe accident computer codes for the integral analysis of the core and the reactor pressure vessel behaviour following the core degradation. The objective of the paper is the comparison of code results obtained by application of different modelling options and the evaluation of influence of thermal hydraulic behaviour of the plant on core damage progression. The analysed transient was postulated station blackout in NPP Krško with a leakage from reactor coolant pump seals. Two groups of calculations were performed where each group had a different break area and, thus, a different leakage rate. Analyses have shown that MAAP4 results were more sensitive to varying thermal hydraulic conditions in the primary system. User-defined parameters had to be carefully selected when the MAAP4 model was developed, in contrast to the RELAP5/SCDAPSIM model where those parameters did not have any significant impact on final results.

  14. Understanding the influence of codon translation rates on cotranslational protein folding.

    Science.gov (United States)

    O'Brien, Edward P; Ciryam, Prajwal; Vendruscolo, Michele; Dobson, Christopher M

    2014-05-20

    Protein domains can fold into stable tertiary structures while they are synthesized by the ribosome in a process known as cotranslational folding. If a protein does not fold cotranslationally, however, it has the opportunity to do so post-translationally, that is, after the nascent chain has been fully synthesized and released from the ribosome. The rate at which a ribosome adds an amino acid encoded by a particular codon to the elongating nascent chain can vary significantly and is called the codon translation rate. Recent experiments have illustrated the profound impact that codon translation rates can have on the cotranslational folding process and the acquisition of function by nascent proteins. Synonymous codon mutations in an mRNA molecule change the chemical identity of a codon and its translation rate without changing the sequence of the synthesized protein. This change in codon translation rate can, however, cause a nascent protein to malfunction as a result of cotranslational misfolding. In some situations, such dysfunction can have profound implications; for example, it can alter the substrate specificity of an ABC transporter protein, resulting in patients who are nonresponsive to chemotherapy treatment. Thus, codon translation rates are crucial in coordinating protein folding in a cellular environment and can affect downstream cellular processes that depend on the proper functioning of newly synthesized proteins. As the importance of codon translation rates makes clear, a necessary aspect of fully understanding cotranslational folding lies in considering the kinetics of the process in addition to its thermodynamics. In this Account, we examine the contributions that have been made to elucidating the mechanisms of cotranslational folding by using the theoretical and computational tools of chemical kinetics, molecular simulations, and systems biology. These efforts have extended our ability to understand, model, and predict the influence of codon

  15. Properties of lipophilic matrix tablets containing phenylpropanolamine hydrochloride prepared by hot-melt extrusion.

    Science.gov (United States)

    Liu, J; Zhang, F; McGinity, J W

    2001-09-01

    The objective of the present study was to investigate the influence of formulation factors on the physical properties of hot-melt extruded granules and compressed tablets containing wax as a thermal binder/retarding agent, and to compare the properties of granules and tablets with those prepared by a high-shear melt granulation (MG) method. Powder blends containing phenylpropanolamine hydrochloride, Precirol and various excipients were extruded in a single-screw extruder at open-end discharge conditions. The extrudates were then passed through a 14-mesh screen to form granules. The extrusion conditions and the optimum amount of wax to function as the thermal binder were dependent on the properties of the filler excipients. At the same wax level, drug release from tablets decreased in the order of using microcrystalline cellulose (MCC), lactose and Emcompress as the filler excipient. The observed differences in the dissolution properties of the tablets were due to the differences in the solubility, swellability and density of the filler excipients. Replacing Precirol with Sterotex K, a higher melting point wax, resulted in slightly increased dissolution rates, when the extrusion was performed at the same temperature conditions. Hot-melt extruded granules were observed to be less spherical than high-shear melt granules and showed lower values of bulk/tap densities. However, tablets containing MCC or lactose granules prepared by hot-melt extrusion (HME) exhibited higher hardness values. Slower drug release rates were found for tablets containing MCC by HME compared with MG. Analysis of the hot-melt extruded granules showed better drug content uniformity among granules of different size ranges compared with high-shear melt granules, resulting in a more reproducible drug release from the corresponding tablets.

  16. Neural mechanisms of the influence of popularity on adolescent ratings of music.

    Science.gov (United States)

    Berns, Gregory S; Capra, C Monica; Moore, Sara; Noussair, Charles

    2010-02-01

    It is well-known that social influences affect consumption decisions. We used functional magnetic resonance imaging (fMRI) to elucidate the neural mechanisms associated with social influence with regard to a common consumer good: music. Our study population was adolescents, age 12-17. Music is a common purchase in this age group, and it is widely believed that adolescent behavior is influenced by perceptions of popularity in their reference group. Using 15-s clips of songs from MySpace.com, we obtained behavioral measures of preferences and neurobiological responses to the songs. The data were gathered with, and without, the overall popularity of the song revealed. Song popularity had a significant effect on the participants' likability ratings of the songs. fMRI results showed a strong correlation between the participants' rating and activity in the caudate nucleus, a region previously implicated in reward-driven actions. The tendency to change one's evaluation of a song was positively correlated with activation in the anterior insula and anterior cingulate, two regions that are associated with physiological arousal and negative affective states. Sensitivity to popularity was linked to lower activation levels in the middle temporal gyrus, suggesting a lower depth of musical semantic processing. Our results suggest that a principal mechanism whereby popularity ratings affect consumer choice is through the anxiety generated by the mismatch between one's own preferences and others'. This mismatch anxiety motivates people to switch their choices in the direction of the consensus. Our data suggest that this is a major force behind the conformity observed in music tastes in some teenagers.

  17. Influence of Addition of Polyols and Food Emulsifiers on the Retrogradation Rate of Starch

    OpenAIRE

    1992-01-01

    The influence of polyols and emulsifiers on hardening of non-glutinous rice starch gels has been investigated. The polyols and emulsifiers were added at concentrations of 6% (w/w) and 0.2% (w/w), respectively , to starch gels (starch content, 30%). The hardening rate and the initial viscoelastic values of gels were computed by analyzing static linear viscoelastic parameters (creep compliance) of the gels stored at 0 C for up to 3,000 minutes. Hardening of gels, i.e., retrogradation of star...

  18. INFLUENCES OF WATER-SOLUBLE CATIONIC MONOMERS ON THE POLYMERIZATION RATE IN THE INVERSE EMULSION

    Institute of Scientific and Technical Information of China (English)

    HOU Sijian; HA Runhua

    1996-01-01

    This investigation deals with the free radical polymerization both of (2-methacryloyloxyethyl) trimethyl ammonium chloride (QACEMA) and of diallyldimethyl ammonium chloride (DADMAC) in inverse emulsion. The influences of some factors, such as the concentration of monomers, initiator and emulsifier are discussed. The polymerization rate equations of above two monomers can be written as follows:Rp = k[M]1.21[I]0.82[E]0.57 (for QACEMA)Rp = k′[M]1.34[I]0.90[E]0.62 (for DADMAC)

  19. Natural and Anthropogenic Influences on Coastal Evolution Rates: St. John, USVI

    Science.gov (United States)

    Wallace, L. E.; Brooks, G. R.; Larson, R. A.; Devine, B.; Holmes, C.; Schwing, P. T.

    2007-05-01

    Sediment cores collected in salt ponds along the coast of St. John, USVI, show that anthropogenic activities have accelerated the rate of coastal evolution. Previous phases of this research indicate that at least some salt ponds form by coral reef growth cutting off open embayments. Over time, ponds fill with island-derived sediments. Rates of sediment accumulation have been shown to increase where anthropogenic activities are present. The objective of this study is to quantify the time required to infill salt ponds in natural and anthropogenically influenced settings. Sediment cores were collected from five salt ponds, chosen primarily on the basis of degree of anthropogenic development within the watershed. Based on detailed geochronological analyses (210Pb, 137Cs, and 7Be for the last 100 years, and 14C for long-term accumulation) we determined accumulation rates using two methods. Linear accumulation rates were calculated to determine sediment accumulation over time. Compacted linear accumulation rates take into consideration compaction of sediments over time. Results show that ponds naturally infill at a rate of 3 - 7 cm/100 yrs. Ponds in pristine watersheds (Newfound Bay) have maintained their natural accumulation rate of 3 - 7 cm/100 yrs. Ponds in areas of low anthropogenic activities (Long Bay/Southgate) infill at 4 - 9 cm/100 yrs, reflecting a slight increase in accumulation due to anthropogenic activity. Ponds moderately impacted by anthropogenic activity (Fish Bay) show a substantial increase of 15 - 20 cm/100 yrs accumulation rate. This compares to heavily impacted areas, such as Coral Bay which has been shown to exhibit a 10-fold increase in sediment accumulation rate over the last 25-50 years. Thus, results show a progressive increase in sediment accumulation rate linked to increasing levels of anthropogenic activities within the associated watershed. Given these rates, ponds naturally become completely infilled in 4,000-6,000 years. Anthropogenic

  20. On the influence of strain rate sensitivity on wear in the Archard regime

    Energy Technology Data Exchange (ETDEWEB)

    Brechet, Y. (Domaine Univ. de Grenoble, Saint Martin d' Heres (France). Lab. de Thermodynamique et Physico-Chimie Metallurgique); Estrin, Y. (Univ. of Western Australia, Nedlands (Australia). Dept. of Mechanical and Materials Engineering)

    1994-06-01

    Relating wear characteristics of a metallic material to its mechanical properties (yield strength, strain hardening coefficient) and its microstructural features (size and volume fraction of inclusions) is a long-standing problem. The diversity of mechanisms which are involved during wear processes makes it practically impossible to have a general theory which would encompass all thinkable situations corresponding to various loads and various regimes of sliding. Different regimes and the conditions for their occurrence have been systematized in wear mechanism maps. In this communication the authors are going to restrict their consideration to plasticity dominated wear which is expected to occur in the low velocity range where surface heating is negligible. In this regime, the prevalent wear mechanism is the removal of slivers of metal by plastic failure due to shearing of contact asperities. The classic works by Rabinowicz have demonstrated clearly that solid friction is a rate dependent problem and that the velocity dependence of dynamic solid friction is nothing else than a consequence of the increase of static solid friction with time during which normal load was applied prior to the commencement of sliding. Creep under normal compression stress leads to flattening of the junctions causing their strength to increase with time. Like solid friction, wear appears to be a rate dependent phenomenon, and the strain rate sensitivity of the flow stress can be expected to be relevant for wear resistance. The strain rate sensitivity is known to play an important role in other damage related properties, such as ductility and fracture toughness. The authors felt that it would be of interest to evaluate the effect of strain rate sensitivity on the wear rate as part of an attempt to relate the wear properties to a bulk constitutive equation, and as a guideline for assessing the influence of alloying elements known to affect the strain rate sensitivity.

  1. Influence of social deprivation, overcrowding and family structure on emergency medical admission rates.

    Science.gov (United States)

    Conway, R; Byrne, D; O'Riordan, D; Cournane, S; Coveney, S; Silke, B

    2016-10-01

    Patients from deprived backgrounds have a higher in-patient mortality following emergency medical admission. To evaluate the influence of Deprivation Index, overcrowding and family structure on hospital admission rates. Retrospective cohort study. All emergency medical admissions from 2002 to 2013 were evaluated. Based on address, each patient was allocated to an electoral division, whose small area population statistics were available from census data. Patients were categorized by quintile of Deprivation Index, overcrowding and family structure, and these were evaluated against hospital admission rate, calculated as rate/1000 population. Univariate and multivariable risk estimates (Odds Ratios or Incidence Rate Ratios) were calculated, using logistic or zero truncated Poisson regression as appropriate. There were 66 861 admissions in 36 214 patients over the 12-year study period. Deprivation Index quintile independently predicted the admission rate, with rates of Q1 12.0 (95% CI 11.8-12.2), Q2 19.5 (95% CI 19.3-19.6), Q3 33.7 (95% CI 33.3-34.0), Q4 31.4 (95% CI 31.2-31.6) and Q5 38.1 (95% CI 37.7-38.5). Similarly the proportions of families with children families with children ≥15-years old was also predictive but quintile of overcrowding was only predictive in the univarate model. Deprivation Index and family structure strongly predict emergency medical hospital admission rates. © The Author 2016. Published by Oxford University Press on behalf of the Association of Physicians. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Magnetic properties of ND Rich Melt-Spun ND-FE-B alloy

    Directory of Open Access Journals (Sweden)

    Grujić Aleksandar

    2005-01-01

    Full Text Available As a part of these experimental investigations of melt-spun Nd-Fe-B alloy with Nd rich content in relation to Nd2Fe14B prepared by rapid quenching process for optimally selected cooling rate and heat treatment, the influence of the chosen chemical composition on magnetic properties was observed. The results of X-ray diffraction, Mössbauer spectroscopy phase analysis and magnetic measurement of investigated melt-spun Nd14.5Fe78.5B7 alloy are presented to bring some new information concerning the relation between their structure and magnetic properties.

  3. The Influences of the Exchange Rate on the Performance of Romanian Trade

    Directory of Open Access Journals (Sweden)

    Gabriela Dobrotă

    2016-01-01

    Full Text Available The unprecedented development of international trade relations has generated the possibility of obtaining a significant part of the GDP of the participating countries in foreign trade. As a result, the issue of competitiveness in international economy has become a major concern to authorities. In the category of factors which are influencing the competitiveness level is registered the volatility of the exchange rate. In this paper there were analyzed the aspects regarding the evolution of Romania's foreign trade and exchange rate, in the context of monetary policy measures. The conclusion is that the development plan of the national economy is determined by the action of a complex of economic, social and political factors, but measures taken by the monetary authorities in relation to the regime of exchange may generate visible effects at this level and thus to the volume of foreign trade relations.

  4. Influence of surgeon's experience and supervision on re-operation rate after hip fracture surgery

    DEFF Research Database (Denmark)

    Palm, Henrik; Jacobsen, Steffen; Krasheninnikoff, Michael

    2006-01-01

    Society of Anaesthesiologists score, New Mobility Score, time to surgery and type of implant, surgery by unsupervised junior registrars was still a significant independent risk factor for re-operation in technically demanding proximal femoral fractures. CONCLUSION: Unsupervised junior registrars should......OBJECTIVE: To investigate the influence of the performing surgeon's experience and degree of supervision on re-operation rate among patients admitted with a proximal femoral fracture (PFF). METHODS: Prospective study of 600 consecutive patients with proximal femoral fracture in our multimodal...... rehabilitation programme, between 2002 and 2004. Re-operation rate was assessed 6 months postoperatively. Surgeons were grouped as unsupervised junior registrars versus experienced surgeons operating or supervising. Fractures were stratified as technically undemanding or demanding. RESULTS: Unsupervised junior...

  5. Influence of surgeon's experience and supervision on re-operation rate after hip fracture surgery

    DEFF Research Database (Denmark)

    Palm, Henrik; Jacobsen, Steffen; Krasheninnikoff, Michael

    2006-01-01

    Society of Anaesthesiologists score, New Mobility Score, time to surgery and type of implant, surgery by unsupervised junior registrars was still a significant independent risk factor for re-operation in technically demanding proximal femoral fractures. CONCLUSION: Unsupervised junior registrars should......OBJECTIVE: To investigate the influence of the performing surgeon's experience and degree of supervision on re-operation rate among patients admitted with a proximal femoral fracture (PFF). METHODS: Prospective study of 600 consecutive patients with proximal femoral fracture in our multimodal...... rehabilitation programme, between 2002 and 2004. Re-operation rate was assessed 6 months postoperatively. Surgeons were grouped as unsupervised junior registrars versus experienced surgeons operating or supervising. Fractures were stratified as technically undemanding or demanding. RESULTS: Unsupervised junior...

  6. The judgment of the All-melted-moment during using electron beam melting equipment to purify silicon

    Science.gov (United States)

    Han, Xiaojie; Meng, Jianxiong; Wang, Shuaiye; Jiang, Tonghao; Wang, Feng; Tan, Yi; Jiang, Dachuan

    2017-06-01

    Experiment has proved that the rate of impurity removal depends on the pressure and the temperature of the vacuum chamber during using electron beam to smelt silicon, and the amount of removed-impurity depends on time when other conditions are the same. In the actual production process, smelting time is a decisive factor of impurity removal amount while pressure and temperature of the vacuum chamber is certain due to a certain melting power. To avoiding the influence of human control and improving the quality of production, thinking of using cooling water temperature to estimate the state of material during metal smelting is considered. We try to use the change of cooling water temperature to judge that when silicon is all melted and to evaluate the effectiveness of this method.

  7. SNPs associated with cerebrospinal fluid phospho-tau levels influence rate of decline in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Carlos Cruchaga

    2010-09-01

    Full Text Available Alzheimer's Disease (AD is a complex and multifactorial disease. While large genome-wide association studies have had some success in identifying novel genetic risk factors for AD, case-control studies are less likely to uncover genetic factors that influence progression of disease. An alternative approach to identifying genetic risk for AD is the use of quantitative traits or endophenotypes. The use of endophenotypes has proven to be an effective strategy, implicating genetic risk factors in several diseases, including anemia, osteoporosis and heart disease. In this study we identify a genetic factor associated with the rate of decline in AD patients and present a methodology for identification of other such factors. We have used an established biomarker for AD, cerebrospinal fluid (CSF tau phosphorylated at threonine 181 (ptau(181 levels as an endophenotype for AD, identifying a SNP, rs1868402, in the gene encoding the regulatory sub-unit of protein phosphatase B, associated with CSF ptau(181 levels in two independent CSF series (P(combined = 1.17 x 10(-05. We show no association of rs1868402 with risk for AD or age at onset, but detected a very significant association with rate of progression of disease that is consistent in two independent series (P(combined = 1.17 x 10(-05. Our analyses suggest that genetic variants associated with CSF ptau(181 levels may have a greater impact on rate of progression, while genetic variants such as APOE4, that are associated with CSF Aβ(42 levels influence risk and onset but not the rate of progression. Our results also suggest that drugs that inhibit or decrease tau phosphorylation may slow cognitive decline in individuals with very mild dementia or delay the appearance of memory problems in elderly individuals with low CSF Aβ(42 levels. Finally, we believe genome-wide association studies of CSF tau/ptau(181 levels should identify novel genetic variants which will likely influence rate of progression of

  8. Factors influencing the contamination rate of human organ-cultured corneas.

    Science.gov (United States)

    Röck, Daniel; Wude, Johanna; Bartz-Schmidt, Karl U; Yoeruek, Efdal; Thaler, Sebastian; Röck, Tobias

    2017-03-21

    To assess the influence of donor, environment and storage factors on the contamination rate of organ-cultured corneas, to consider the microbiological species causing corneal contamination and to investigate the corresponding sensitivities. Data from 1340 consecutive donor corneas were analysed retrospectively. Logistic regression analysis was used to assess the influence of different factors on the contamination rate of organ-cultured corneas for transplantation. The mean annual contamination rate was 1.8 ± 0.4% (range: 1.3-2.1%); 50% contaminations were of fungal origin with exclusively Candida species, and 50% contaminations were of bacterial origin with Staphylococcus species being predominant. The cause of donor death including infection and multiple organ dysfunction syndrome increased the risk of bacterial or fungal contamination during organ culture (p = 0.007 and p = 0.014, respectively). Differentiating between septic and aseptic donors showed an increased risk of contamination for septic donors (p = 0.0020). Mean monthly temperature including warmer months increased the risk of contamination significantly (p = 0.0031). Sex, donor age, death to enucleation, death to corneoscleral disc excision and storage time did not increase the risk of contamination significantly. The genesis of microbial contamination in organ-cultured donor corneas seems to be multifactorial. The main source of fungal or bacterial contamination could be resident species from the skin flora. The rate of microbial contamination in organ-cultured donor corneas seems to be dependent on the cause of donor death and mean monthly temperature. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  9. Simulations of water transport through carbon nanotubes: how different water models influence the conduction rate.

    Science.gov (United States)

    Liu, L; Patey, G N

    2014-11-14

    The conduction rate of water through (8,8) and (9,9) carbon nanotubes at 300 K and a pressure difference of 220 MPa is investigated using molecular dynamics simulations. The TIP3P, SPC/E, and TIP4P/2005 water models are considered. The pressure-driven flow rate is found to be strongly model dependent for both nanotubes. The fastest model (TIP3P) has a flow rate that is approximately five times faster than the slowest (TIP4P/2005). It is shown that the flow rate is significantly influenced by the structure taken on by the water molecules confined in the nanotube channels. The slower models, TIP4P/2005 and SPC/E, tend to favor stacked ring arrangements, with the molecules of a ring moving together through the nanotube, in what we term a "cluster-by-cluster" conduction mode. Confined TIP3P water has a much weaker tendency to form ring structures, and those that do form are fragile and break apart under flow conditions. This creates a much faster "diffusive" conduction mode where the water molecules mainly move through the tube as individual particles, rather than as components of a larger cluster. Our results demonstrate that water models developed to describe the properties of bulk water can behave very differently in confined situations.

  10. The influence of SPS heating rates on the synthesis reaction of tantalum diboride

    Directory of Open Access Journals (Sweden)

    Jolanta Laszkiewicz-Łukasik

    2016-07-01

    Full Text Available TaB2 is a material from the Ultra High Temperature Ceramics group and is rather unexplored because it is difficult to procure the raw materials and to densify TaB2. Using SPS technique to realize reactive sintering processes of powders mixture according to the reaction Ta + 2B → TaB2 makes it possible to achieve TaB2 in one technological step. The aim of the study was to determine the influence of heating rates on the synthesis reaction and on the multistage densification mechanisms during SPS processes. The mixture was sintered at constant parameters of 2200 °C, 48 MPa for 5 min with the usage of heating rates from 50 °C/min up to 400 °C/min. The densification processes were studied through analyzing the shrinkage of powder compacts during SPS (Spark Plasma Sintering processes. The comparison of the densification curves indicates that the reactions do not proceed completely at slow heating rates. Namely, too low heating rates contribute to the sintering of tantalum before the synthesis reaction and demonstrate the presence of boron in liquid state. The best material obtained in this study has Young's modulus 571 GPa, Vickers hardness 20.7 GPa (HV1 and indentation fracture toughness KIC 4.7 MPa m1/2.

  11. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    Science.gov (United States)

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca i

    2017-01-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C. PMID:28262840

  12. Solar Influence on Nuclear Decay Rates: Constraints from the MESSENGER Mission

    CERN Document Server

    Fischbach, Ephraim; Gold, Robert E; Goldsten, John O; Lawrence, David J; McNutt, Ralph J; Rhodes, Edgar A; Jenkins, Jere H; Longuski, John

    2011-01-01

    We have analyzed Cs-137 decay data, obtained from a small sample onboard the MESSENGER spacecraft en route to Mercury, with the aim of setting limits on a possible correlation between nuclear decay rates and solar activity. Such a correlation has been suggested recently on the basis of data from Mn-54 decay during the solar flare of 13 December 2006, and by indications of an annual and other periodic variations in the decay rates of Si-32, Cl-36, and Ra-226. Data from five measurements of the Cs-137 count rate over a period of approximately 5.4 years have been fit to a formula which accounts for the usual exponential decrease in count rate over time, along with the addition of a theoretical solar contribution varying with MESSENGER-Sun separation. The indication of solar influence is then characterized by a non-zero value of the calculated parameter \\xi, and we find \\xi=(2.8+/-8.1)x10^{-3} for Cs-137. A simulation of the increased data that can hypothetically be expected following Mercury orbit insertion on 1...

  13. Communication: Theory of melt-memory in polymer crystallization

    Science.gov (United States)

    Muthukumar, M.

    2016-07-01

    Details of crystallization processes of a polymer at the crystallization temperature Tc from its melt kept initially at the melt temperature Tm depend profoundly on the nature of the initial melt state and often are accompanied by memory effects. This phenomenon is in contrast to small molecular systems where the supercooling (Tm0-Tc), with Tm0 being the equilibrium melting temperature, and not (Tm - Tc), determines the nature of crystallization. In addressing this five-decade old puzzle of melt-memory in polymer crystallization, we present a theory to describe melt-memory effects, by invoking an intermediate inhomogeneous melt state in the pathway between the melt and crystalline states. Using newly introduced dissolution temperature T10 for the inhomogeneous melt state and the transition temperature Tt0 for the transition between the inhomogeneous melt and crystalline states, analytical formulas are derived for the nucleation rate as a function of the melt temperature. The theory is general to address different kinds of melt-memory effects depending on whether Tm is higher or lower than Tm0. The derived results are in qualitative agreement with known experimental data, while making predictions for further experiments on melt-memory.

  14. Influence of different hematoma clearance rates on patients with hypertensive intracerebral hemorrhage

    Institute of Scientific and Technical Information of China (English)

    Cheng Zhong; Jing-Zhu Shi; Yu Liu; Tao Ou; Guo-Jing Liu; Bin Wang

    2016-01-01

    Objective:To evaluate the influence of different hematoma clearance rates patients with hypertensive intracerebral hemorrhage.Methods: A total of 94 cases with hypertensive intracerebral hemorrhage treated with operation from June 2012 to June 2015 were selected. According to theirhematoma clearance rates, they were divided into groups A (50%-70%, 28 cases), B (70%-90%,48 cases) and C (90%, 18 cases). The recovery and perioperative levels of serum neuron-specific enolase (NSE) and soluble S-100 protein of the three groups were compared.Results: The perioperative mortality and the rates of postoperative rebleeding, intracranial infection and other complications of the three groups showed no statistical significant difference (P>0.05). With the increase of the hematoma clearance rate, the drainage tube removal time and hematoma complete absorption time reduced significantly (P<0.05). In the groups B and C, the grade levels of ADL in postoperative 3 months were significantly superior to those in the group A (P<0.05). The levels of serum NSE and S-100 in the three groups increased in the initial stage and then declined after surgery. In the group B and C, the serum levels of NSE and S-100 were significantly higher than those in the group A on the 7th day after surgery (P<0.05). With the increase of the hematoma clearance rate, the serum levels of NSE and S-100 were significantly reduced on the 14th day after surgery (P<0.05). Conclusions:High level of hematoma clearance rate can help to increase the operation efficacy and prognosis of patients with hypertensive intracerebral hemorrhage.

  15. The rate of visitation by Amazilia fimbriata (Apodiformes: Trochilidae influences seed production in Tillandsia stricta (Bromeliaceae

    Directory of Open Access Journals (Sweden)

    Caio C.C. Missagia

    2015-06-01

    Full Text Available Legitimate flowers visitors pollinate the flower during the visit and thus influence the production of fruits and seeds. We tested whether the visitation rate of potential pollinators is associated with the amount of seeds per fruit produced by the self-compatible bromeliad Tillandsia stricta (Bromeliaceae. We determined whether hummingbirds are legitimate visitors by testing for a correlation between visits and pollination (seed production at the Guapiaçú Ecological Reserve (Reserva Ecológica de Guapiaçú, state of Rio de Janeiro. We tested 30 flowers, five of which were also monitored to test the possibility of spontaneous self-pollination. The remaining 25 flowers were exposed to floral visitors. Twenty-two flowers formed fruits and seeds, from which three formed seeds without floral visits. The hummingbird Amazilia fimbriata (Gmelin, 1788 was the only legitimate visitor. The average number (± standard deviation of seeds was 27 units (±15 per fruit. The floral visitation rate by A. fimbriata was 6.6 (±3.4 visits/per flower. The number of floral visits and the amount of seed produced were positively correlated (r² = 0.58, p < 0.01. Thus, A. fimbriata is a legitimate floral visitor of T. stricta, and influences seed production per fruit in this bromeliad.

  16. Influences of gender and anthropometric features on inspiratory inhaler acoustics and peak inspiratory flow rate.

    Science.gov (United States)

    Taylor, Terence E; Holmes, Martin S; Sulaiman, Imran; Costello, Richard W; Reilly, Richard B

    2015-01-01

    Inhalers are hand-held devices used to treat chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD). Medication is delivered from an inhaler to the user through an inhalation maneuver. It is unclear whether gender and anthropometric features such as age, height, weight and body mass index (BMI) influence the acoustic properties of inspiratory inhaler sounds and peak inspiratory flow rate (PIFR) in inhalers. In this study, healthy male (n=9) and female (n=7) participants were asked to inhale at an inspiratory flow rate (IFR) of 60 L/min in four commonly used inhalers (Turbuhaler(™), Diskus(™), Ellipta(™) and Evohaler(™)). Ambient inspiratory sounds were recorded from the mouthpiece of each inhaler and over the trachea of each participant. Each participant's PIFR was also recorded for each of the four inhalers. Results showed that gender and anthropometric features have the potential to influence the spectral properties of ambient and tracheal inspiratory inhaler sounds. It was also observed that males achieved statistically significantly higher PIFRs in each inhaler in comparison to females (p<;0.05). Acoustic features were found to be significantly different across inhalers suggesting that acoustic features are modulated by the inhaler design and its internal resistance to airflow.

  17. Growth of ɛ-caprolactam crystals from the melt: The influence of cyclohexanone on the {1 1 1¯} and {1 1 0} forms

    Science.gov (United States)

    van den Berg, E. P. G.; Bögels, G.; Arkenbout, G. J.

    1998-01-01

    The (1 1 1¯) and (1 1 0) facets of ɛ-caprolactam growing from the melt appear to grow with different mechanisms. This is caused by the different molecular structure of the (1 1 1¯) and the (1 1 0) facets. Moreover, the cyclohexanone impurity concentration in front of the interface changes the growth mechanism leading to different distribution coefficients for each facet. Usually, in industry overall distribution coefficients are used and the crystal form is only of interest because of the filterability of the crystals. Here it is shown that a second factor, the growth mechanism of each facet has to be taken into account when considering the optimal conditions for growing pure crystals.

  18. Influence of processing medium on frictional wear properties of ball bearing steel prepared by laser surface melting coupled with bionic principles

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Hong, E-mail: wangct08@mails.jlu.edu.c [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Wang Chengtao [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Faw-Volkswagen Automotive Company Ltd., Changchun 130011 (China); Guo Qingchun [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Brilliance Automobile Engineering Research Institute, Shenyang 110141 (China); Yu Jiaxiang [Key Lab of Automobile Materials, Ministry of Education, Jilin University, Changchun 130025 (China); Wang Mingxing [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100190 (China); Liao Xunlong [Technical Management Department, CNNC China Zhongyuan Engineering Corp. Ltd., No 487 Tianlin Road, Shanghai 200233 (China); Zhao Yu [School of Materials Science and Engineering, Changchun University of Technology, Changchun 130012 (China); Ren Luquan [Key Lab of Terrain Machinery Bionics Engineering, Ministry of Education, Jilin University, Changchun 130025 (China)

    2010-09-03

    Coupling with bionic principles, an attempt to improve the wear resistance of ball bearing steel (GCr15) with biomimetic units on the surface was made using a pulsed Nd: YAG laser. Air and water film was employed as processing medium, respectively. The microstructures of biomimeitc units were examined by scanning electron microscope and X-ray diffraction was used to describe the microstructure and identify the phases as functions of different mediums as well as water film with different thicknesses. The results indicated that the microstructure zones in the biomimetic specimens processed with water film were more refined and had better wear resistance increased by 55.8% in comparison with that processed in air; a significant improvement in microhardness was achieved by laser surface melting. The application of water film provided considerable microstructural changes and much more regular grain shape in biomimetic units, which played a key role in improving the wear resistance of ball bearing steel.

  19. Evaluation of the influence of alcohol dehydrogenase polymorphisms on alcohol elimination rates in African Americans.

    Science.gov (United States)

    Marshall, Vanessa J; Ramchandani, Vijay A; Kalu, Nnenna; Kwagyan, John; Scott, Denise M; Ferguson, Clifford L; Taylor, Robert E

    2014-01-01

    The relationship between alcohol dehydrogenase (ADH) polymorphisms and alcohol use disorders in populations of African descent has not been clearly established. This study examined the effect of ADH1B polymorphisms on alcohol metabolism and subjective response, following intravenous (IV) alcohol administration, and the influence of gender, recent drinking history, and family history of alcoholism (FHA), in nondependent African American drinkers. The sample included eighty-seven 21- to 35-year-old, light social drinkers of African descent. Participants included 39 sib pairs, 2 sibships with 3 siblings each, and 3 individuals who were not part of a sibship. Participants received infusions via the use of the clamp method that refers to the goal of controlling breath alcohol concentration in 2 randomized sessions at 0.06 g% ethanol and 0 mg% (placebo), and a battery of subjective scales at predefined time points. Dependent measures included alcohol elimination rates (AERs), alcohol disappearance rates (ADRs), subjective measures peak scores, and area under the curve. General linear model and mixed models were performed to examine the relationship between ADH1B genotype, dependent measures, and influence of covariates. Participants with ADH1B1/1 genotypes showed higher number of drinks (p = 0.023) and drinks per drinking day (p = 0.009) compared with the persons with ADH1B1/3 genotype. AER (adjusted for body weight) was higher in ADH1B*1 homozygotes (p = 0.045) compared with ADH1B1/3 heterozygotes. ADR differed significantly between males and females (p = 0.002), regardless of body weight (p = 0.004) and lean body mass (p alcohol sessions compared with placebo sessions (p alcohol pharmacokinetics following IV alcohol administration in nondependent drinkers of African descent. Session (alcohol vs. placebo) and ADH1B genotype did, however, influence subjective response to alcohol with some variation by gender, FHA, and drinks per drinking day. Copyright © 2013 by the

  20. Heart rate recovery after aerobic and anaerobic tests: is there an influence of anaerobic speed reserve?

    Science.gov (United States)

    Del Rosso, Sebastián; Nakamura, Fabio Y; Boullosa, Daniel A

    2017-05-01

    The present study assessed if differences in the metabolic profile, inferred from the anaerobic speed reserve (ASR), would influence the dynamics of heart rate recovery (HRR) after two modes of exercise. Thirty-nine physical education students (14 females and 25 males) volunteered for this study. Participants carried out three separate testing sessions to assess maximal sprinting speed (MSS, 1st session), repeated sprint ability (RSA, 2nd session) and maximal aerobic speed (MAS) using the Université of Montreal Track Test (UMTT, 3rd session). ASR was defined as the difference between MSS and MAS. Heart rate was continuously registered throughout the tests and during the 5-min post-test recovery. To evaluate the influence of ASR on post-exercise, HRR comparisons between ASR-based groups [high ASR vs. low ASR] and sex groups (males vs. females) were performed. Significant differences (P < 0.05) were found between high ASR and low ASR groups of the same sex for indices of relative HRR after the RSA and UMTT. In addition, after the RSA test, males from the high ASR group had a significantly slower HRR kinetics compared with the males of the low ASR (P < 0.05) and the females of high ASR (P < 0.05); whereas females of the high ASR groups had a faster HRR kinetics compared with the females of low ASR group (P < 0.05). Our results showed that in males, post-exercise HRR could be related to the ASR, whereas in females, the influence of ASR is less clear.

  1. Subcritical crack growth and mechanical weathering: a new consideration of how moisture influences rock erosion rates.

    Science.gov (United States)

    Eppes, Martha-Cary; Keanini, Russell; Hancock, Gregory S.

    2016-04-01

    The contributions of moisture to the mechanical aspects of rock weathering and regolith production are poorly quantified. In particular, geomorphologists have largely overlooked the role of subcritical crack growth processes in physical weathering and the fact that moisture strongly influences the rates of those processes. This influence is irrespective of the function that moisture plays in stress loading mechanisms like freezing or hydration. Here we present a simple numerical model that explores the efficacy of subcritical crack growth in granite rock subaerially exposed under a range of moisture conditions. Because most weathering-related stress loading for rocks found at, or near, Earth's surface (hereafter surface rocks) is cyclic, we modeled crack growth using a novel combination of Paris' Law and Charles' Law. This combination allowed us to apply existing empirically-derived data for the stress corrosion index of Charles' Law to fatigue cracking. For stress, we focused on the relatively straightforward case of intergranular stresses that arise during solar-induced thermal cycling by conductive heat transfer, making the assumption that such stresses represent a universal minimum weathering stress experienced by all surface rocks. Because all other tensile weathering-related stresses would be additive in the context of crack growth, however, our model can be adapted to include other stress loading mechanisms. We validated our calculations using recently published thermal-stress-induced cracking rates. Our results demonstrate that 1) weathering-induced stresses as modeled herein, and as published by others, are sufficient to propagate fractures subcritically over long timescales with or without the presence of water 2) fracture propagation rates increase exponentially with respect to moisture, specifically relative humidity 3) fracture propagation rates driven by thermal cycling are strongly dependent on the magnitude of diurnal temperature ranges and the

  2. Individual condition, standard metabolic rate, and rearing temperature influence steelhead and rainbow trout (Oncorhynchus mykiss) life histories

    Science.gov (United States)

    Matthew R. Sloat; Gordon H. Reeves

    2014-01-01

    We reared juvenile Oncorhychus mykiss with low and high standard metabolic rates (SMR) under alternative thermal regimes to determine how these proximate factors influence life histories in a partially migratory salmonid fish. High SMR significantly decreased rates of freshwater maturation and increased rates of smoltification in females, but not...

  3. Influence of layered precursor pellets on the growth and properties of Y-Ba-Cu-O bulk superconductors by top-seeded melt-textured growth

    Science.gov (United States)

    Tang, Tian-wei; Wu, Dong-jie; Xu, Ke-Xi

    2016-03-01

    It is well known that a fine and homogeneous distribution of Y2BaCuO5 (Y211) phase particles in single-grain Y-Ba-Cu-O (YBCO) bulk superconductors is essential for improving field-trapping ability. However, the size and concentration of Y211 phase particles in the fully melt-processed superconducting bulk increase significantly with the distance from the seed, which results in the accumulation of Y211 phase particles and the degradation of superconducting properties. In this paper, we report a new method of fabricating single-grain YBCO using layered precursor pellets. Using the top-seeded melt-textured growth process, single-grain YBCO bulk superconductors of about 22 mm in diameter and 9 mm in thickness were fabricated from layered precursor pellets and standard precursor pellets, respectively. The layered precursor pellets consist of precursor powders with 40 mol% Y211 at the top, 30 mol% Y211 in the middle and 20 mol% Y211 at the bottom of the whole pellets, while standard precursor pellets are prepared from precursor powders with only 40 mol% Y211. The growth morphology, microstructure and magnetic flux properties of the layered samples and standard samples were comparatively studied. The results proved that the layered precursor pellets allow a sufficient growth in the c-growth sector and a more uniform distribution of the Y211 phase in the matrix. The distribution of Y211 phase particles is qualitatively explained by the prevalent trapping/pushing theory. The trapped field at 77 K reaches 0.8 T, nearly 29% higher than the standard sample. The present results are very valuable for further improving the properties of YBCO bulk superconductors.

  4. Influence of Low-Temperature Plasma Treatment on The Liquid Filtration Efficiency of Melt-Blown PP Nonwovens in The Conditions of Simulated Use of Respiratory Protective Equipment

    Directory of Open Access Journals (Sweden)

    Majchrzycka Katarzyna

    2017-06-01

    Full Text Available Filtering nonwovens produced with melt-blown technology are one of the most basic materials used in the construction of respiratory protective equipment (RPE against harmful aerosols, including bio- and nanoaerosols. The improvement of their filtering properties can be achieved by the development of quasi-permanent electric charge on the fibres. Usually corona discharge method is utilized for this purpose. In the presented study, it was assumed that the low-temperature plasma treatment could be applied as an alternative method for the manufacturing of conventional electret nonwovens for the RPE construction. Low temperature plasma treatment of polypropylene nonwovens was carried out with various process gases (argon, nitrogen, oxygen or air in a wide range of process parameters (gas flow velocity, time of treatment and power supplied to the reactor electrodes. After the modification, nonwovens were evaluated in terms of filtration efficiency of paraffin oil mist. The stability of the modification results was tested after 12 months of storage and after conditioning at elevated temperature and relative humidity conditions. Moreover, scanning electron microscopy and ATR-IR spectroscopy were used to assess changes in surface topography and chemical composition of the fibres. The modification of melt-blown nonwovens with nitrogen, oxygen and air plasma did not result in a satisfactory improvement of the filtration efficiency. In case of argon plasma treatment, up to 82% increase of filtration efficiency of paraffin oil mist was observed in relation to untreated samples. This effect was stable after 12 months of storage in normal conditions and after thermal conditioning in (70 ± 3°C for 24 h. The use of low-temperature plasma treatment was proven to be a promising improvement direction of filtering properties of nonwovens used for the protection of respiratory tract against harmful aerosols.

  5. Partitioning coefficients between olivine and silicate melts

    Science.gov (United States)

    Bédard, J. H.

    2005-08-01

    Variation of Nernst partition coefficients ( D) between olivine and silicate melts cannot be neglected when modeling partial melting and fractional crystallization. Published natural and experimental olivine/liquidD data were examined for covariation with pressure, temperature, olivine forsterite content, and melt SiO 2, H 2O, MgO and MgO/MgO + FeO total. Values of olivine/liquidD generally increase with decreasing temperature and melt MgO content, and with increasing melt SiO 2 content, but generally show poor correlations with other variables. Multi-element olivine/liquidD profiles calculated from regressions of D REE-Sc-Y vs. melt MgO content are compared to results of the Lattice Strain Model to link melt MgO and: D0 (the strain compensated partition coefficient), EM3+ (Young's Modulus), and r0 (the size of the M site). Ln D0 varies linearly with Ln MgO in the melt; EM3+ varies linearly with melt MgO, with a dog-leg at ca. 1.5% MgO; and r0 remains constant at 0.807 Å. These equations are then used to calculate olivine/liquidD for these elements using the Lattice Strain Model. These empirical parameterizations of olivine/liquidD variations yield results comparable to experimental or natural partitioning data, and can easily be integrated into existing trace element modeling algorithms. The olivine/liquidD data suggest that basaltic melts in equilibrium with pure olivine may acquire small negative Ta-Hf-Zr-Ti anomalies, but that negative Nb anomalies are unlikely to develop. Misfits between results of the Lattice Strain Model and most light rare earth and large ion lithophile partitioning data suggest that kinetic effects may limit the lower value of D for extremely incompatible elements in natural situations characterized by high cooling/crystallization rates.

  6. A benchmark initiative on mantle convection with melting and melt segregation

    Science.gov (United States)

    Schmeling, Harro; Dohmen, Janik; Wallner, Herbert; Noack, Lena; Tosi, Nicola; Plesa, Ana-Catalina; Maurice, Maxime

    2015-04-01

    In recent years a number of mantle convection models have been developed which include partial melting within the asthenosphere, estimation of melt volumes, as well as melt extraction with and without redistribution at the surface or within the lithosphere. All these approaches use various simplifying modelling assumptions whose effects on the dynamics of convection including the feedback on melting have not been explored in sufficient detail. To better assess the significance of such assumptions and to provide test cases for the modelling community we initiate a benchmark comparison. In the initial phase of this endeavor we focus on the usefulness of the definitions of the test cases keeping the physics as sound as possible. The reference model is taken from the mantle convection benchmark, case 1b (Blanckenbach et al., 1989), assuming a square box with free slip boundary conditions, the Boussinesq approximation, constant viscosity and a Rayleigh number of 1e5. Melting is modelled assuming a simplified binary solid solution with linearly depth dependent solidus and liquidus temperatures, as well as a solidus temperature depending linearly on depletion. Starting from a plume free initial temperature condition (to avoid melting at the onset time) three cases are investigated: Case 1 includes melting, but without thermal or dynamic feedback on the convection flow. This case provides a total melt generation rate (qm) in a steady state. Case 2 includes batch melting, melt buoyancy (melt Rayleigh number Rm), depletion buoyancy and latent heat, but no melt percolation. Output quantities are the Nusselt number (Nu), root mean square velocity (vrms) and qm approaching a statistical steady state. Case 3 includes two-phase flow, i.e. melt percolation, assuming a constant shear and bulk viscosity of the matrix and various melt retention numbers (Rt). These cases should be carried out using the Compaction Boussinseq Approximation (Schmeling, 2000) or the full compaction

  7. Influences of Organic Carbon Supply Rate on Uranium Bioreduction in Initially Oxidizing, Contaminated Sediment

    Energy Technology Data Exchange (ETDEWEB)

    Tokunaga, Tetsu K.; Wan, Jiamin; Kim, Yongman; Daly, Rebecca A.; Brodie, Eoin L.; Hazen, Terry C.; Herman, Don; Firestone, Mary K.

    2008-06-10

    Remediation of uranium (U) contaminated sediments through in-situ stimulation of bioreduction to insoluble UO{sub 2} is a potential treatment strategy under active investigation. Previously, we found that newly reduced U(IV) can be reoxidized under reducing conditions sustained by a continuous supply of organic carbon (OC) because of residual reactive Fe(III) and enhanced U(VI) solubility through complexation with carbonate generated through OC oxidation. That finding motivated this investigation directed at identifying a range of OC supply rates that is optimal for establishing U bioreduction and immobilization in initially oxidizing sediments. The effects of OC supply rate, from 0 to 580 mmol OC (kg sediment){sup -1} year{sup -1}, and OC form (lactate and acetate) on U bioreduction were tested in flow-through columns containing U-contaminated sediments. An intermediate supply rate on the order of 150 mmol OC (kg sediment){sup -1} year{sup -1} was determined to be most effective at immobilizing U. At lower OC supply rates, U bioreduction was not achieved, and U(VI) solubility was enhanced by complexation with carbonate (from OC oxidation). At the highest OC supply rate, resulting highly carbonate-enriched solutions also supported elevated levels of U(VI), even though strongly reducing conditions were established. Lactate and acetate were found to have very similar geochemical impacts on effluent U concentrations (and other measured chemical species), when compared at equivalent OC supply rates. While the catalysts of U(VI) reduction to U(IV) are presumably bacteria, the composition of the bacterial community, the Fe reducing community, and the sulfate reducing community had no direct relationship with effluent U concentrations. The OC supply rate has competing effects of driving reduction of U(VI) to low solubility U(IV) solids, as well as causing formation of highly soluble U(VI)-carbonato complexes. These offsetting influences will require careful control of OC

  8. Influence of increased heart rate and aortic pressure on resting indices of functional coronary stenosis severity.

    Science.gov (United States)

    Casadonte, Lorena; Verhoeff, Bart-Jan; Piek, Jan J; VanBavel, Ed; Spaan, Jos A E; Siebes, Maria

    2017-09-13

    Baseline assessment of functional stenosis severity has been proposed as a practical alternative to hyperemic indices. However, intact autoregulation mechanisms may affect intracoronary hemodynamics. The aim of this study was to investigate the effect of changes in aortic pressure (Pa) and heart rate (HR) on baseline coronary hemodynamics and functional stenosis assessment. In 15 patients (55 ± 3% diameter stenosis) Pa, intracoronary pressure (Pd) and flow velocity were obtained at control, and during atrial pacing at 120 bpm, increased Pa (+30 mmHg) with intravenous phenylephrine (PE), and elevated Pa while pacing at sinus heart rate (PE + sHR). We derived rate pressure product (RPP = systolic Pa × HR), baseline microvascular resistance (BMR = Pd/velocity), and stenosis resistance [BSR = (Pa - Pd)/velocity] as well as whole-cycle Pd/Pa. Tachycardia (120 ± 1 bpm) raised RPP by 74% vs. Accordingly, BMR decreased by 27% (p stenosis severity, causing Pd/Pa and BSR of borderline lesions to cross the diagnostic threshold. In conclusion, coronary microvascular adaptation to physiological conditions affecting metabolic demand at rest influences intracoronary hemodynamics, which may lead to altered basal stenosis indices used for clinical decision-making.

  9. Influence of Vegetable Oil on the Thermal Aging Rate of Kraft Paper and its Mechanism

    Institute of Scientific and Technical Information of China (English)

    YANG Lijun; DENG Bangfei; LIAO Ruijin; SUN Caixin; ZHU Mengzhao

    2012-01-01

    With the development of new insulation materials,vegetable oil—the best substitute for mineral oil—has gradually been widely used in the liquid insulation of transformers.To investigate the influence of vegetable oil on the thermal aging rate of oil paper,Kraft paper impregnated with mineral oil and vegetable oil have been underwent thermally accelerated aging at three different temperatures.The degree of polymerization(DP) of Kraft paper was measured to indicate the aging degree of insulation paper.The aging rate of Kraft paper in mineral oil and vegetable oil was compared quantitatively,and results showed that vegetable oil retarded paper's degradation rate and extended its useful lifetime.The reasons contributing to such phenomena were analyzed using X-ray Photoelectron Spectroscopy(XPS) and molecular simulation software.Kraft paper in vegetable oil had larger activation energy.Due to the larger interaction force between water and natural ester molecules,water molecules were easily bonded with natural ester,weakening the hydrolysis process of cellulose.Cellulose was chemically modified by natural ester during the thermal aging process,and the reactive-OH(hydroxyl) groups on the cellulose became esterified with fatty acid esters.Water molecules were firmly bounded to the ester groups on glucose produced by esterification.The long-chain fatty acid esterified to cellulose was parallel with cellulose chains and acted as a "water barrier" to further weaken the hydrolysis process.

  10. Influence of deep breathing exercise on spontaneous respiratory rate and heart rate variability: a randomised controlled trial in healthy subjects.

    Science.gov (United States)

    Tharion, Elizabeth; Samuel, Prasanna; Rajalakshmi, R; Gnanasenthil, G; Subramanian, Rajam Krishna

    2012-01-01

    Studies show that yogic type of breathing exercises reduces the spontaneous respiratory rate. However, there are no conclusive studies on the effects of breathing exercise on heart rate variability. We investigated the effects of non-yogic breathing exercise on respiratory rate and heart rate variability. Healthy subjects (21-33 years, both genders) were randomized into the intervention group (n=18), which performed daily deep breathing exercise at 6 breaths/min (0.1 Hz) for one month, and a control group (n=18) which did not perform any breathing exercise. Baseline respiratory rate and short-term heart rate variability indices were assessed in both groups. Reassessment was done after one month and the change in the parameters from baseline was computed for each group. Comparison of the absolute changes [median (inter-quartile ranges)] of the parameters between the intervention and control group showed a significant difference in the spontaneous respiratory rate [intervention group -2.50 (-4.00, -1.00), control group 0.00 (-1.00, 1.00), cycles/min, Pchanges produced by simple deep slow breathing exercise in the respiratory rate and cardiac autonomic modulation of the intervention group were significant, when compared to the changes in the control group. Thus practice of deep slow breathing exercise improves heart rate variability in healthy subjects, without altering their cardiac autonomic balance. These findings have implications in the use of deep breathing exercises to improve cardiac autonomic control in subjects known to have reduced heart rate variability.

  11. 扫描间距对45钢激光熔凝强化组织性能的影响%Influence of scanning interval on microstructure and abrasive wear resistance of 45 Steel by laser melting

    Institute of Scientific and Technical Information of China (English)

    孙浩; 凌刚; 李洪文; 高晓丽; 姚国才

    2011-01-01

    为了研究扫描间距对45钢激光熔凝强化组织性能的影响,采用HLD1001-5型固体激光器对45钢表面进行了多条带等间距激光熔凝处理,分别利用扫描电镜、洛氏硬度计、磨损试验机观察和测量了不同扫描间距下硬化层的显微组织及性能.结果表明:激光熔凝处理的硬化层由熔化区、相变硬化区和热影响区组成,组织为马氏体:多条带等间距激光熔凝处理在垂直于熔凝条带方向上的硬度分布由左高硬度区、左过渡区、低硬度区、右过渡区和右高硬度区组成,高硬度区的硬度为58.1~59.6 HRC,低硬度区的硬度约16 HRC:在试验范围内,经激光扫描间距为4.5 mm熔凝处理的试样具有最好的耐磨性.%A variety of the multi-stripe and equal-interval laser melting treatments on the surface of 45 Steel samples were obtained using HLD1001.5 solid-state laser for studying the influence of scanning interval on the microstructure and abrasive wear resistance of 45 Steel by laser melting.The microstructure and properties of the samples were studied by SEM, Rockwell hardness tester and wear tester.The results showed that the hardened layer by laser melting was composed of melted zone, phase transformation zone and heat affected zone.The hardened layer was a martensite microstructure.The Rockwell hardness distribution was composed of left high value zone, left transitional zone, low value zone, right transitional hardness zone and right high value zone.The hardness at high value zone and low value zone was 58.1-59.6 HRC and 16 HRC respectively.Under the conditions of the experiment, the samples with the treatment of 4.5 mm scanning interval featured the best abrasive wear resistance.

  12. Studies of thermal dissolution of RDX in TNT melt

    Science.gov (United States)

    Suvorova, N. A.; Hamilton, V. T.; Oschwald, D. M.; Balakirev, F. F.; Smilowitz, L. B.; Henson, B. F.

    2017-01-01

    The thermal response of energetic materials is studied due to its importance in issues of material safety and surety. Secondary high explosives which melt before they thermally decompose present challenging systems to model due to the addition of material flow. Composition B is a particularly challenging system due to its multiphase nature with a low melt component (TNT) and a high melt component (RDX). The dissolution of RDX crystals in molten TNT at the temperature below RDX melting point has been investigated using hot stage microscopy. In this paper, we present data on the dissolution rate of RDX crystals in molten TNT as a function of temperature above the TNT melt.

  13. Melting Behaviour of Ferronickel Slags

    Science.gov (United States)

    Sagadin, Christoph; Luidold, Stefan; Wagner, Christoph; Wenzl, Christine

    2016-12-01

    The industrial manufacturing of ferronickel in electric furnaces produces large amounts of slag with strong acidic character and high melting points, which seriously stresses the furnace refractory lining. In this study, the melting behavior of synthetically produced ferronickel slags on magnesia as refractory material was determined by means of a hot stage microscope. Therefore, slags comprising the main oxides SiO2 (35-70 wt.%), MgO (15-45 wt.%) and Fe2O3 (5-35 wt.%) were melted in a graphite crucible and afterwards analyzed by a hot stage microscope. The design of experiments, which was created by the statistic software MODDE®, included 20 experiments with varying slag compositions as well as atmospheres. The evaluation of the test results occurred at three different characteristic states of the samples like the softening point according to DIN 51730 and the temperatures at which the area of residual cross-section of the samples amounted to 30% and 40%, respectively, of the original value depending of their SiO2/MgO ratio and iron oxide content. Additionally, the thickness of the zone influenced by the slag was measured and evaluated.

  14. Influences of organic matter and calcification rate on trace elements in aragonitic estuarine bivalve shells

    Science.gov (United States)

    Takesue, R.K.; Bacon, C.R.; Thompson, J.K.

    2008-01-01

    ., Bruguier O., Ordinola E., Barrett N. T. and Fontugne M. (2006) Calcification rate influence on trace element concentrations in aragonitic bivalve shells: evidences and mechanisms. Geochim. Cosmochim. Acta 70, 4906-4920] which predicts that [M]/Ca ratios increase as calcification rates increase and Ca2+ channel specificity decreases. This result, in combination with the possibility that there were ontogenetic variations in growth rates among individuals younger than 2 years, underscores the need to develop an independent age model for C. amurensis shells. If growth-rate effects on lattice-bound [M]/Ca ratios can be constrained, it may yet be possible to develop high-resolution geochemical proxies for external solution chemistry in low-salinity regions of SFB.

  15. Signatures of nonthermal melting

    Directory of Open Access Journals (Sweden)

    Tobias Zier

    2015-09-01

    Full Text Available Intense ultrashort laser pulses can melt crystals in less than a picosecond but, in spite of over thirty years of active research, for many materials it is not known to what extent thermal and nonthermal microscopic processes cause this ultrafast phenomenon. Here, we perform ab-initio molecular-dynamics simulations of silicon on a laser-excited potential-energy surface, exclusively revealing nonthermal signatures of laser-induced melting. From our simulated atomic trajectories, we compute the decay of five structure factors and the time-dependent structure function. We demonstrate how these quantities provide criteria to distinguish predominantly nonthermal from thermal melting.

  16. INFLUENCE OF THE MODERN SYSTEMS OF THE BLAST STEEL-FURNACE ELECTRICAL PARAMETERS CONTROL ON CAPACITY AND TECHNICAL AND ECONOMICAL INDICES OF MELTING

    Directory of Open Access Journals (Sweden)

    D. N. Andrianov

    2006-01-01

    Full Text Available The reduction of time under the current, electric energy rate, electrodes rate at working of arc steel-furnace with new transformer of capacity 95 MBA and with regulating system SIMELT-AC-NEC are noted.

  17. H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones

    Science.gov (United States)

    Labrousse, L.; Duretz, T.; Gerya, T.

    2015-10-01

    We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H2O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H2O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 1017 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure-temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H2O-fluid-saturated partial melting

  18. The influence of physical exertion on basic hematological parameters values and heart rate in trotters

    Directory of Open Access Journals (Sweden)

    Slijepčević Dajana

    2014-01-01

    Full Text Available One of very important prerequisites for achieving good results in races, in addition to genetic predisposition, quality training and good health, are optimal values for number of erythrocytes, concentration of haemoglobin and hematocrit, of which depends efficient oxygen supply of muscles during great efforts. The stated values, along with data on heart rate, are useful indicators of the degree of horse fitness and readiness for horse race. The influence of physical exertion on the values of basic hematological parameters as well as on heart rate, was investigated on 6 trotters, in training at the Belgrade racetrack (one head of Italian trotter, male, 3 years old; 3 heads of American trotter, male, 3,4 and 6 years old and two heads of Serbian trotter, female, 4 and 5 years old. The blood samples for hematological tests were taken by punction of jugular vein in resting phase - immediately before the commencement of work, after light trot warming for 3000 m and fast trot for 1000 m, with 30 minutes rest between the two runnings. The heart rate was monitored continuously by radio telemetry cardiometer, from the moment they were taken from their boxes and harnessing to the completion of work. The obtained results confirm the relationship between the rise of heart rate and hematocrit values: maximal hematocrit values were determined after the first running (0.49±0.05, in regard to 0.42±0.03 in resting phase, but 30 minutes after the second running there was a slight drop of hematocrit values (0.46±0.04. The blood samples in both cases were taken after fast trot during which there were recorded maximal pulse values, so in the moment of sampling the pulse lowered close to the values in resting - after the first running from 192.23±19.66, and after the second from 180.33±17.22 to 40.67±5.76.

  19. Influence of the lifetime parameter on the rotation rate of sunspots

    Science.gov (United States)

    Zuccarello, F.

    1993-05-01

    Recent investigations on the photospheric angular velocity pattern have shown that young and short- living tracers show rotation rates higher than those determined both by older tracers and by photospheric plasma. As a direct relationship between the age of the tracer and the angular velocity determination has been found (Zappalà & Zuccarello 1991), it seemed very interesting to investigate whether also the "lifetime" parameter might have a role on angular velocity determinations. We have therefore analyzed the sunspot-group data reported in the Greenwich Photoheliographic Results during the 1874-1976 period. 9000 objects were selected as young sunspot-groups (YSG) and, using the lifetime parameter as selecting rule, we could catalogue 4463 objects having a lifetime between 2 and 10 d. The rotation rate of these objects as a function of their lifetime was calculated and the results obtained may be summarized in the following main points: 1. Independently of their lifetime, sunspots rotate during the first 2-3 days of life in the photosphere, at a higher rate than that of recurrent sunspots. 2. Sunspots with a lifetime ranging from 2 to 8 d are more efficiently decelerated than YSG, while 11-day living sunspots are less efficiently decelerated. 3. Sunspots in the equatorial belt (0-10°) having a lifetime comparable to that of supergranule cells, rotate slower than the cells themselves. 4. The angular velocity measured during the last day of life is lower both than that of YSG and than that deduced by sunspots which disappear the day after. These results have been analyzed in the scenario of the sunspots cluster model ( 1987). According to the conclusions drawn, the initial higher angular velocity of young and short-living sunspots is not a function of the cluster "aggregation capability"; the rate of rise of the merging level through the convection zone is influenced by (or influences) the ability of the cluster to keep coalesced; finally, when the merging level

  20. INFLUENCE OF THE PHYSICAL STATE OF THE BACTERIAL CELL MEMBRANE UPON THE RATE OF RESPIRATION.

    Science.gov (United States)

    HENNEMAN, D H; UMBREIT, W W

    1964-06-01

    Henneman, Dorothy H. (Rutgers, The State University, New Brunswick, N.J.), and W. W. Umbreit. Influence of the physical state of the bacterial cell membrane upon the rate of respiration. J. Bacteriol. 87:1274-1280. 1964.-NaCl and KCl in concentrations of the order of 0.2 to 0.5 m inhibit the respiration of Escherichia coli B and other gram-negative organisms. Cell-free enzymes concerned in respiration and prepared from the same organisms are not inhibited by these salts, whereas these same enzymes tested in intact cells are. The physical state of the cell membrane appears to be a factor controlling its respiratory activity.

  1. The influence of speech rate and accent on access and use of semantic information.

    Science.gov (United States)

    Sajin, Stanislav M; Connine, Cynthia M

    2017-04-01

    Circumstances in which the speech input is presented in sub-optimal conditions generally lead to processing costs affecting spoken word recognition. The current study indicates that some processing demands imposed by listening to difficult speech can be mitigated by feedback from semantic knowledge. A set of lexical decision experiments examined how foreign accented speech and word duration impact access to semantic knowledge in spoken word recognition. Results indicate that when listeners process accented speech, the reliance on semantic information increases. Speech rate was not observed to influence semantic access, except in the setting in which unusually slow accented speech was presented. These findings support interactive activation models of spoken word recognition in which attention is modulated based on speech demands.

  2. Influence of process parameters on thermal-rate treatment of ZA42 alloy

    Institute of Scientific and Technical Information of China (English)

    李成栋; 田学雷; 赵梅; 耿浩然

    2002-01-01

    Sand casting process and directional solidification technique combining thermal-rate treatment(TRT) were used. The influence of process parameters on TRT was investigated according to the values of impact toughness. At the same time, the mechanism of TRT was discussed. The results showed that TRT can improve the impact toughness of this alloy, while the hardness is basically constant. The time of heat preservation should not be more than 5min. Different forms of cooling intensification additive have different effects among which the zinc ingot solidified in graphite mold is the best one that can improve impact toughness of samples by more than 80%. With increasing the cooling temperature, the value of α(Al) crystal lattice constant increases. The element Sb has negative effect on TRT.

  3. The Influence of the Active Rate of Interest over the Financing Decision of the Enterprise

    Directory of Open Access Journals (Sweden)

    Irena Munteanu

    2008-06-01

    Full Text Available The elaboration of some coherent strategies of development of the long term firms requires the existence of material resources which ensures, besides other necessary competences, the development and the pereniality of the firm. The enterprise has multiple choices of financing its activities: the credit lines, the treasury lines, the discount of the commerce effects, factoring, and leasing and investment credits. Tasking into account the Romanian market, one notices that the most important financing source at which the enterprises appeal to is represented by the nongovernmental credits. The main purpose of the article is to determine how the modification of the rate of interest can influence the structure of the capital and which are the particularities of this dependency for the Romanian market.

  4. The influence of pressure on the intrinsic dissolution rate of amorphous indomethacin

    DEFF Research Database (Denmark)

    Löbmann, Korbinian; Flouda, Konstantina; Qiu, Danwen

    2014-01-01

    New drug candidates increasingly tend to be poorly water soluble. One approach to increase their solubility is to convert the crystalline form of a drug into the amorphous form. Intrinsic dissolution testing is an efficient standard method to determine the intrinsic dissolution rate (IDR) of a drug...... and to test the potential dissolution advantage of the amorphous form. However, neither the United States Pharmacopeia (USP) nor the European Pharmacopeia (Ph.Eur) state specific limitations for the compression pressure in order to obtain compacts for the IDR determination. In this study, the influence......, compression pressure had an impact on the IDR of pure amorphous IND compacts. Above a critical compression pressure, amorphous particles sintered to form a single compact with dissolution properties similar to quench-cooled disc and crystalline IND compacts. In such a case, the apparent dissolution advantage...

  5. Intrinsic and extrinsic influences on standard metabolic rates of three species of Australian otariid.

    Science.gov (United States)

    Ladds, Monique A; Slip, David J; Harcourt, Robert G

    2017-01-01

    The study of marine mammal energetics can shed light on how these animals might adapt to changing environments. Their physiological potential to adapt will be influenced by extrinsic factors, such as temperature, and by intrinsic factors, such as sex and reproduction. We measured the standard metabolic rate (SMR) of males and females of three Australian otariid species (two Australian fur seals, three New Zealand fur seals and seven Australian sea lions). Mean SMR ranged from 0.47 to 1.05 l O2 min(-1), which when adjusted for mass was from 5.33 to 7.44 ml O2 min(-1) kg(-1). We found that Australian sea lion mass-specific SMR (sSMR; in millilitres of oxygen per minute per kilogram) varied little in response to time of year or moult, but was significantly influenced by sex and water temperature. Likewise, sSMR of Australian and New Zealand fur seals was also influenced by sex and water temperature, but also by time of year (pre-moult, moult or post-moult). During the moult, fur seals had significantly higher sSMR than at other times of the year, whereas there was no discernible effect of moult for sea lions. For both groups, females had higher sSMR than males, but sea lions and fur seals showed different responses to changes in water temperature. The sSMR of fur seals increased with increasing water temperature, whereas sSMR of sea lions decreased with increasing water temperature. There were no species differences when comparing animals of the same sex. Our study suggests that fur seals have more flexibility in their physiology than sea lions, perhaps implying that they will be more resilient in a changing environment.

  6. Influence of cell detachment on the respiration rate of tumor and endothelial cells.

    Science.gov (United States)

    Danhier, Pierre; Copetti, Tamara; De Preter, Géraldine; Leveque, Philippe; Feron, Olivier; Jordan, Bénédicte F; Sonveaux, Pierre; Gallez, Bernard

    2013-01-01

    Cell detachment is a procedure routinely performed in cell culture and a necessary step in many biochemical assays including the determination of oxygen consumption rates (OCR) in vitro. In vivo, cell detachment has been shown to exert profound metabolic influences notably in cancer but also in other pathologies, such as retinal detachment for example. In the present study, we developed and validated a new technique combining electron paramagnetic resonance (EPR) oximetry and the use of cytodex 1 and collagen-coated cytodex 3 dextran microbeads, which allowed the unprecedented comparison of the OCR of adherent and detached cells with high sensitivity. Hence, we demonstrated that both B16F10 melanoma cells and human umbilical vein endothelial cells (HUVEC) experience strong OCR decrease upon trypsin or collagenase treatments. The reduction of cell oxygen consumption was more pronounced with a trypsin compared to a collagenase treatment. Cells remaining in suspension also encounter a marked intracellular ATP depletion and an increase in the lactate production/glucose uptake ratio. These findings highlight the important influence exerted by cell adhesion/detachment on cell respiration, which can be probed with the unprecedented experimental assay that was developed and validated in this study.

  7. The influence of the gas flow rate during methane biofiltration on an inorganic packing material

    Energy Technology Data Exchange (ETDEWEB)

    Nikiema, J.; Heitz, M. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering

    2009-02-15

    Sanitary landfills are a major anthropogenic source of methane (CH{sub 4}), an important greenhouse gas (GHG). In 2005, sanitary landfills contributed nearly 25 per cent of the total atmospheric CH{sub 4} emissions in Canada. In order to address this concern, 52 landfills were equipped with gas collection systems in 2005. This study measured the influence of the gas flow rate (GFR) on CH{sub 4} elimination through biofiltration and estimated the maximum level of GFR that allowed conversions within the biofilter above 90 per cent. Since CH{sub 4} biodegrades in the biofilter due to microbial activity, the efficiency of this bioprocess is affected by the number and type of microorganisms present in the biofilter. This study also compared the performance of the biofilter under different gas flow regimes, at two different phosphorus concentrations. The experiments involved the use of a nitrogen minimal salt nutrient solution, for the biofilter periodic irrigation, in which the nitrogen concentration was maintained at 0.75 g/L, while the phosphorus concentration was 1.5 g/L. The objective was to determine if the phosphorus concentration can modify the influence of the GFR on the biofilter. The results showed that the GFR is an important parameter which affects the biofilter performance. It was concluded that the biofiltration process requires a high phosphorus level in the nutrient solution. 23 refs., 2 tabs., 5 figs.

  8. Field study suggests that sex determination in sea lamprey is directly influenced by larval growth rate

    Science.gov (United States)

    Johnson, Nicholas; Swink, William D.; Brenden, Travis O.

    2017-01-01

    Sex determination mechanisms in fishes lie along a genetic-environmental continuum and thereby offer opportunities to understand how physiology and environment interact to determine sex. Mechanisms and ecological consequences of sex determination in fishes are primarily garnered from teleosts, with little investigation into basal fishes. We tagged and released larval sea lamprey (Petromyzon marinus) into unproductive lake and productive stream environments. Sex ratios produced from these environments were quantified by recapturing tagged individuals as adults. Sex ratios from unproductive and productive environments were initially similar. However, sex ratios soon diverged, with unproductive environments becoming increasingly male-skewed and productive environments becoming less male-skewed with time. We hypothesize that slower growth in unproductive environments contributed to the sex ratio differences by directly influencing sex determination. To the best of our knowledge, this is the first study suggesting that growth rate in a fish species directly influences sex determination; other studies have suggested that the environmental variables to which sex determination is sensitive (e.g. density, temperature) act as cues for favourable or unfavourable growth conditions. Understanding mechanisms of sex determination in lampreys may provide unique insight into the underlying principles of sex determination in other vertebrates and provide innovative approaches for their management where valued and invasive.

  9. Fast dissolving cyclodextrin complex of piroxicam in solid dispersion part I: influence of β-CD and HPβ-CD on the dissolution rate of piroxicam.

    Science.gov (United States)

    Bouchal, F; Skiba, M; Chaffai, N; Hallouard, F; Fatmi, S; Lahiani-Skiba, M

    2015-01-30

    Sublingual drug delivery is an interesting route for drug having significant hepatic first-pass metabolism or requiring rapid pharmacological effect as for patients suffering from swallowing difficulties, nausea or vomiting. Sublingual absorption could however be limited by the kinetic of drug dissolution. This study evaluated influences of cyclodextrins (β-CD or HP-β-CD) and their different inclusion process (spray-drying or freeze-drying) on the drug dissolution kinetic of solid dispersions in poly(ethylene glycol) (PEG, Mw 6000Da) of piroxicam, used as poor hydrosoluble drug model. A secondary objective was to determine influences of drug dispersion process in PEG (evaporation or melting methods) on the drug dissolution kinetic of piroxicam. Piroxicam solid dispersions containing or not cyclodextrins were characterized by different scanning calorimetry (DSC), Thermogravometry analyser (TGA) and Fourier transform-infrared spectroscopy (FT-IR) spectroscopy. In vitro drug dissolution study of these solid dispersions was then performed. The results demonstrated the high potential and interest of solid dispersions of drug previously included in cyclodextrins for sublingual delivery of hydrophobic drugs. This study also showed the advantages of evaporation method on the melting ones during drug dispersion in PEG. Indeed, drug complexation with cyclodextrins as dispersion by melting prevented the presence in solid dispersions of drug in crystalline form which can represent up to 63%. Moreover, dispersion in PEG by evaporation method gave more porous drug delivery system than with melting methods. This allowed complete (limited at most at 80-90% with melting methods) and quick drug dissolution without rebound effect like with melting ones.

  10. Influence of Doping and Nanostructuration on n-Type Bi2(Te0.8Se0.2)3 Alloys Synthesized by Arc Melting

    Science.gov (United States)

    Gharsallah, Mouna; Serrano-Sanchez, Federico; Nemes, Norbert M.; Martinez, Jose Luis; Alonso, Jose Antonio

    2017-01-01

    In competitive thermoelectric devices for energy conversion and generation, high-efficiency materials of both n-type and p-type are required. For this, Bi2Te3-based alloys have the best thermoelectric properties in room temperature applications. Partial replacement of tellurium by selenium is expected to introduce new donor states in the band gap, which would alter electrical conductivity and thermopower. We report on the preparation of n-type Bi2(Te1-xSex)3 solid solutions by a straightforward arc-melting technique, yielding nanostructured polycrystalline pellets. X-ray and neutron powder diffraction was used to assess Se inclusion, also indicating that the interactions between quintuple layers constituting this material are weakened upon Se doping, while the covalency of intralayer bonds is augmented. Moreover, scanning electron microscopy shows large surfaces perpendicular to the c crystallographic axis assembled as stacked sheets. Grain boundaries related to this 2D nanostructuration affect the thermal conductivity reducing it below 0.8 Wm-1K-1 at room temperature. Furthermore, Se doping increases the absolute Seebeck coefficient up to -140 μV K-1 at 400 K, which is also beneficial for improved thermoelectric efficiency.

  11. Influence of heat treatments on the microstructure and tensile behaviour of selective laser melting-produced TI-6AL-4V parts

    Directory of Open Access Journals (Sweden)

    Ter Haar, Gerrit Matthys

    2016-11-01

    Full Text Available In industry, post-process heat treatments of Ti-6Al-4V are performed with the aim of improving its tensile behaviour. While heat treatments of wrought Ti6Al4V have been standardised (e.g., Aerospace Material Specification H-81200, heat treatments of selective laser melting (SLM-produced Ti-6Al-4V lacks research and understanding. Significant concern exists about SLM Ti6-Al-4V’s achievable ductility attributed to its martensitic (α’ phase. In this research, heat treatments at a range of temperatures are applied to SLM-produced Ti-6Al-4V tensile samples. Microstructural analysis (both optically and through electron backscatter diffraction was used to identify links between heat treatments and microstructure. Subsequently, uniaxial tensile tests were performed to determine the respective tensile properties of all samples. Correlations in the data show a significant loss in strength with respect to an increase in annealing temperature due to grain growth, while no noticeable trend was observed for fracture strain with regard to annealing temperatures.

  12. Influence of composition on the structure and properties of SrO–Sb2O3–P2O5 low-melting sealing glasses

    Directory of Open Access Journals (Sweden)

    Nie Haining

    2015-12-01

    Full Text Available SrO–Sb2O3–P2O5 glass system was prepared by high temperature melting method. The effects of Sb2O3 and P2O5 content on the structure, thermal behavior and chemical durability of the glasses were studied by infrared spectrometer, thermal dilatometer, differential thermal analyzer and constant temperature water bath heating. It can be concluded that the characteristic temperatures of the glasses increased firstly and then decreased with the increasing of Sb2O3 content, whereas the tendency of the coefficient of thermal expansion (CTE varied inversely. The crystallization ability of the glasses was significantly increased and the water resistance was reduced for Sb2O3 content of 35 mol % and 40 mol %. The glasses with 20 mol %, 25 mol % and 30 mol % Sb2O3 showed better performance in every respect than the others and the glasses containing 25 mol % Sb2O3, characterized by the best performance, can be chosen as host glasses for further research.

  13. Solidification at the High and Low Rate Extreme

    Energy Technology Data Exchange (ETDEWEB)

    Meco, Halim [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  14. Melt Cast High Explosives

    Directory of Open Access Journals (Sweden)

    Stanisław Cudziło

    2014-12-01

    Full Text Available [b]Abstract[/b]. This paper reviews the current state and future developments of melt-cast high explosives. First the compositions, properties and methods of preparation of trinitrotoluene based (TNT conventional mixtures with aluminum, hexogen (RDX or octogen (HMX are described. In the newer, less sensitive explosive formulations, TNT is replaced with dinitroanisole (DNANDNANDNAN and nitrotriazolone (NTONTONTO, nitroguanidine (NG or ammonium perchlorate (AP are the replacement for RDRDX and HMX. Plasticized wax or polymer-based binder systems for melt castable explosives are also included. Hydroxyl terminated polybutadiene (HPTB is the binder of choice, but polyethylene glycol, and polycaprolactone with energetic plasticizers are also used. The most advanced melt-cast explosives are compositions containing energetic thermoplastic elastomers and novel highly energetic compounds (including nitrogen rich molecules in whose particles are nanosized and practically defect-less.[b]Keywords[/b]: melt-cast explosives, detonation parameters

  15. Melting of sodium clusters

    CERN Document Server

    Reyes-Nava, J A; Beltran, M R; Michaelian, K

    2002-01-01

    Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid transition in the sodium clusters are analyzed by calculating physical quantities like caloric curves, heat capacities, and root-mean-square bond length fluctuations using simulation times of several nanoseconds. Distinct melting mechanisms are obtained for the sodium clusters in the size range investigated. The calculated melting temperatures show an irregular variation with the cluster size, in qualitative agreement with recent experimental results. However, the calculated melting point for the Na_55 cluster is about 40 % lower than the experimental value.

  16. Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variability.

    Science.gov (United States)

    Wiklund, Urban; Karlsson, Marcus; Oström, Mats; Messner, Torbjörn

    2009-01-01

    Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise. Ten healthy volunteers (five men and five women aged 19-30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0.75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery. No subject developed any clinically significant arrhythmias. Post-exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone. The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations.

  17. Spatial and temporal melt variability at Helheim Glacier, East Greenland, and its effect on ice dynamics

    DEFF Research Database (Denmark)

    Andersen, M. L.; Larsen, T. B.; Nettles, M.

    2010-01-01

    Understanding the behavior of large outlet glaciers draining the Greenland Ice Sheet is critical for assessing the impact of climate change on sea level rise. The flow of marine-terminating outlet glaciers is partly governed by calving-related processes taking place at the terminus but is also...... influenced by the drainage of surface runoff to the bed through moulins, cracks, and other pathways. To investigate the extent of the latter effect, we develop a distributed surface-energy-balance model for Helheim Glacier, East Greenland, to calculate surface melt and thereby estimate runoff. The model...... is driven by data from an automatic weather station operated on the glacier during the summers of 2007 and 2008, and calibrated with independent measurements of ablation. Modeled melt varies over the deployment period by as much as 68% relative to the mean, with melt rates approximately 77% higher...

  18. Stented ureterovesical anastomosis in renal transplantation: does it influence the rate of urinary tract infections?

    Directory of Open Access Journals (Sweden)

    Mathe Z

    2010-07-01

    Full Text Available Abstract Objective Our objective was to evaluate the impact of routine use of double-J stents on the incidence of urinary tract infection after renal transplantation. Methods We conducted a retrospective-comparative single-centre study in 310 consecutive adult deceased donor kidney recipients transplanted from 2002 to 2006. Patients were divided in two groups, with or without urinary stent implantation. To evaluate the predictive factors for UTI, donor and recipients pre- and post-transplantation data were analysed. Early urological complications and renal function within 12 months of transplantation were included as well. Results A total of 157 patients were enrolled to a stent (ST and 153 patients to a no-stent (NST group. The rate of urinary tract infection at three months was similar between the two groups (43.3% ST vs. 40.1% NST, p = 0.65. Of the identified pathogens Enterococcus and Escherichia coli were the most common species. In multivariate analysis neither age nor immunosuppressive agents, BMI or diabetes seemed to have influence on the rate of UTI. When compared to males, females had a significantly higher risk for UTI (54.0% vs. 33.5%. Conclusion Prophylactic stenting of the ureterovesical anastomosis does not increase the risk of urinary tract infection in the early postoperative period.

  19. Influence of antenatal physical exercise on heart rate variability and QT variability.

    Science.gov (United States)

    Carpenter, R E; Emery, S J; Uzun, O; Rassi, D; Lewis, M J

    2017-01-01

    We sought to characterise the influence of an antenatal exercise programme on ECG-derived cardiac variables. Fifity-one healthy pregnant women were recruited and randomly assigned (2 × 2×2 design) to an exercise group or a control group. Exercising groups attended weekly classes from the 20th week of pregnancy onwards. Cardiovascular assessments (heart rate variabiliy (HRV), QT, and the QT variability index (QTVI)) were performed at 12-16, 26-28, 34-36 weeks and 12 weeks following birth, during supine rest and exercise conditions. Advancing gestation was associated with an increased maternal heart rate (p = 0.001), shorter QT interval (p = 0.003), diminished HRV (p = 0.002) and increased QTVI (p = 0.002). Each of these changes was reversed within 12 weeks postpartum (p Exercise group displayed exaggerated changes for all variables (except QT) but only during supine rest in the third trimester (p exercise programme undertaken between mid and late pregnancy exaggerated these changes during rest in the third trimester of pregnancy.

  20. Influence of bacterial activities on nitrogen uptake rates determined by the application of antibiotics

    Directory of Open Access Journals (Sweden)

    Clavery Tungaraza

    2003-09-01

    Full Text Available The influence of bacterial activities on inorganic nutrients has always affected total phytoplankton uptake rates owing to the absence of a reliable method that can exclude these effects. The use of natural samples to determine the contribution of bacterial activities has been based on the size fractionation method which, unfortunately, is encumbered with uncertainties, especially because of the size overlap between bacteria and phytoplankton communities. In this paper, the results are reported of an estimation of bacterial activities by the use of inhibitors (antibiotics. It was shown that the contribution of bacterial activities to the uptake of nitrogenous nutrients was highest for ammonium (79%, followed by nitrate (72% and urea (62%. In a second set of experiments the concentration of ammonium was raised by 5 µM. This was done to avoid nutrient limitation resulting from the absence of recycled nutrients following the addition of antibiotics and the maximum contribution of bacterial activity to the uptake rate of ammonium increased to 87%. It can be concluded that the use of inhibitors is a good method, a reliable alternative to the fractionation method. However, it is important to note that inhibitors can affect both phytoplankton growth and the nutrient recycling process. Our results indicate that the application of antibiotics had measurable effects not only on the target bacteria but also on the uptake behaviour of phytoplankton. Our observations were therefore limited to the period when there was no effect on the phytoplankton, as was demonstrated by a carbon protein incorporation experiment.

  1. Influence of strategic management in Czech SMEs and their growth rate

    Directory of Open Access Journals (Sweden)

    Jaroslav Vrchota

    2016-12-01

    Full Text Available The aim of the managers in SMEs is to have a competitive enterprise on the market, to develop and achieve some positive results. The successful strategic management has to adapt to the external environment, analyse emerging issues in time and react quickly and flexibly to changes. With the increasing amounts of business entities, strategic analysis and strategy as such acquire their importance. The basic data for the creation of strategy includes information about the external environment, i.e. about the market and its surroundings and internal business environment. Those managers, who can use the advantages of their enterprise and market opportunities and reduce the effect of weaknesses and threats, may ensure their enterprise prosperity and increase their growth rate. However, they must choose a competitive strategy, with which it is possible to succeed on the market. Such strategy provides SMEs the possibility of differentiation, setting a higher level of services offered to enhance customer satisfaction which is the most important. The paper deals with finding whether the strategic management of SME influences the growth rate of an enterprise. Data were gathered as questionnaires and interviews from 183 enterprises operating in the Czech Republic. The research was made in the period of 2014-15.

  2. Factors influencing the adolescent pregnancy rate in the Greater Giyani Municipality, Limpopo Province – South Africa

    Directory of Open Access Journals (Sweden)

    Lenny Mushwana

    2015-01-01

    Full Text Available A quantitative, descriptive and explorative survey was conducted to determine factors that influence adolescent pregnancy rate among teenage girls (n = 147 attending four high schools in the Greater Giyani Municipality in South Africa. Data was collected using a validated questionnaire which had a reliability of 0.65. Response frequency distributions, two-way frequency tables, Chi-square tests and Cochran–Armitage Trend Tests were used to determine the effect with the demographic characteristics of participants. Participants reported that health services were not conveniently available for them. Their relationship with nurses was poor (p < 0.05 as reported by 73% of participants with regard to maintenance of confidentiality. Participants reported key psychosocial variables such as inadequate sexual knowledge (61%, changing attitudes towards sex (58.9% and peer pressure (56.3% as contributory to high pregnancy rate. Recommendations were made to improve school health services, reproductive education in school curricula focussing on reproductive health, sexuality and guidance for future research.

  3. Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    Mérel Philippe

    2010-01-01

    Full Text Available Abstract Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO2 layer.

  4. Force induced DNA melting

    Energy Technology Data Exchange (ETDEWEB)

    Santosh, Mogurampelly; Maiti, Prabal K [Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore-12 (India)], E-mail: santosh@physics.iisc.ernet.in, E-mail: maiti@physics.iisc.ernet.in

    2009-01-21

    When pulled along the axis, double-strand DNA undergoes a large conformational change and elongates by roughly twice its initial contour length at a pulling force of about 70 pN. The transition to this highly overstretched form of DNA is very cooperative. Applying a force perpendicular to the DNA axis (unzipping), double-strand DNA can also be separated into two single-stranded DNA, this being a fundamental process in DNA replication. We study the DNA overstretching and unzipping transition using fully atomistic molecular dynamics (MD) simulations and argue that the conformational changes of double-strand DNA associated with either of the above mentioned processes can be viewed as force induced DNA melting. As the force at one end of the DNA is increased the DNA starts melting abruptly/smoothly above a critical force depending on the pulling direction. The critical force f{sub m}, at which DNA melts completely decreases as the temperature of the system is increased. The melting force in the case of unzipping is smaller compared to the melting force when the DNA is pulled along the helical axis. In the case of melting through unzipping, the double-strand separation has jumps which correspond to the different energy minima arising due to sequence of different base pairs. The fraction of Watson-Crick base pair hydrogen bond breaking as a function of force does not show smooth and continuous behavior and consists of plateaus followed by sharp jumps.

  5. Modeling the Temperature Fields of Copper Powder Melting in the Process of Selective Laser Melting

    Science.gov (United States)

    Saprykin, A. A.; Ibragimov, E. A.; Babakova, E. V.

    2016-08-01

    Various process variables influence on the quality of the end product when SLM (Selective Laser Melting) synthesizing items of powder materials. The authors of the paper suggest using the model of distributing the temperature fields when forming single tracks and layers of copper powder PMS-1. Relying on the results of modeling it is proposed to reduce melting of powder particles out of the scanning area.

  6. Considerations regarding the influence of the base leading rate over actualization rate of investment projects financed by EU funds

    OpenAIRE

    Attila Tamaş SZORA; Iulian Bogdan DOBRA

    2010-01-01

    The investment process is a complex economic process that implies risks. Allotting capital resources in an investment project without using an adequate discount rate of the cash flows, which will take into account the evolution of the base leading rate of NBR (National Bank of Romania), can lead to the total or partial loss of the invested capital by the European Union, by Romania’s government and by the applicants. There is a permanent concern from the experts to find an adequate indicator t...

  7. Lessons learnt from FARO/TERMOS corium melt quenching experiments

    Energy Technology Data Exchange (ETDEWEB)

    Magallon, D.; Huhtiniemi, I.; Hohmann, H. [Commission of the European Communities, Ispra (Italy). Joint Research Center

    1998-01-01

    The influence of melt quantity, melt composition, water depth and initial pressure on quenching is assessed on the basis of seven tests performed in various conditions in the TERMOS vessel of the FARO facility at JRC-Ispra. Tests involved UO{sub 2}-based melt quantities in the range 18-176 kg at a temperature of approximately 3000 K poured into saturated water. The results suggest that erosion of the melt jet column is an efficient contributor to the amount of break-up, and thus quenching, for large pours of corium melt. The presence of Zr metal in the melt induced a much more efficient quenching than in a similar test with no Zr metal, attributed to the oxidation of the Zr. Significant amounts of H{sub 2} were produced also in tests with pure oxidic melts (e.g. about 300 g for 157 kg melt). In the tests at 5.0 and 2.0 MPa good mixing with significant melt break-up and quenching was obtained during the penetration in the water. At 0.5 MPa, good penetration of the melt into the water could still be achieved, but a jump in the vessel pressurisation occurred when the melt contacted the bottom and part (5 kg) of the debris was re-ejected from the water. (author)

  8. Regional variability in sea ice melt in a changing Arctic.

    Science.gov (United States)

    Perovich, Donald K; Richter-Menge, Jacqueline A

    2015-07-13

    In recent years, the Arctic sea ice cover has undergone a precipitous decline in summer extent. The sea ice mass balance integrates heat and provides insight on atmospheric and oceanic forcing. The amount of surface melt and bottom melt that occurs during the summer melt season was measured at 41 sites over the time period 1957 to 2014. There are large regional and temporal variations in both surface and bottom melting. Combined surface and bottom melt ranged from 16 to 294 cm, with a mean of 101 cm. The mean ice equivalent surface melt was 48 cm and the mean bottom melt was 53 cm. On average, surface melting decreases moving northward from the Beaufort Sea towards the North Pole; however interannual differences in atmospheric forcing can overwhelm the influence of latitude. Substantial increases in bottom melting are a major contributor to ice losses in the Beaufort Sea, due to decreases in ice concentration. In the central Arctic, surface and bottom melting demonstrate interannual variability, but show no strong temporal trends from 2000 to 2014. This suggests that under current conditions, summer melting in the central Arctic is not large enough to completely remove the sea ice cover. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Influence of ammonia oxidation rate on thaumarchaeal lipid composition and the TEX86 temperature proxy.

    Science.gov (United States)

    Hurley, Sarah J; Elling, Felix J; Könneke, Martin; Buchwald, Carolyn; Wankel, Scott D; Santoro, Alyson E; Lipp, Julius Sebastian; Hinrichs, Kai-Uwe; Pearson, Ann

    2016-07-12

    Archaeal membrane lipids known as glycerol dibiphytanyl glycerol tetraethers (GDGTs) are the basis of the TEX86 paleotemperature proxy. Because GDGTs preserved in marine sediments are thought to originate mainly from planktonic, ammonia-oxidizing Thaumarchaeota, the basis of the correlation between TEX86 and sea surface temperature (SST) remains unresolved: How does TEX86 predict surface temperatures, when maximum thaumarchaeal activity occurs below the surface mixed layer and TEX86 does not covary with in situ growth temperatures? Here we used isothermal studies of the model thaumarchaeon Nitrosopumilus maritimus SCM1 to investigate how GDGT composition changes in response to ammonia oxidation rate. We used continuous culture methods to avoid potential confounding variables that can be associated with experiments in batch cultures. The results show that the ring index scales inversely (R(2) = 0.82) with ammonia oxidation rate (ϕ), indicating that GDGT cyclization depends on available reducing power. Correspondingly, the TEX86 ratio decreases by an equivalent of 5.4 °C of calculated temperature over a 5.5 fmol·cell(-1)·d(-1) increase in ϕ. This finding reconciles other recent experiments that have identified growth stage and oxygen availability as variables affecting TEX86 Depth profiles from the marine water column show minimum TEX86 values at the depth of maximum nitrification rates, consistent with our chemostat results. Our findings suggest that the TEX86 signal exported from the water column is influenced by the dynamics of ammonia oxidation. Thus, the global TEX86-SST calibration potentially represents a composite of regional correlations based on nutrient dynamics and global correlations based on archaeal community composition and temperature.

  10. Submarine Melting of Icebergs from Repeat High-Resolution Digital Elevation Models

    Science.gov (United States)

    Enderlin, E. M.; Hamilton, G. S.; Straneo, F.; Cenedese, C.

    2014-12-01

    Icebergs calved from tidewater glaciers act as distributed freshwater sources as they transit through fjords to the surrounding ocean basins. Glacier discharge estimates provide a crude approximation of the total iceberg discharge on inter-annual timescales, but the liquid freshwater flux from icebergs in glacial fjords is largely unknown. Here we use repeat high-resolution digital elevation models (DEMs) to derive meltwater fluxes for 18 icebergs in Sermilik Fjord, East Greenland, during the 2011-2013 boreal summers, and for 33 comparably-sized icebergs in Ilulissat Fjord, West Greenland, during March-April 2011 and July 2012. We find that iceberg melt rates for Sermilik Fjord are in good agreement with simulated melt rates along the vertical terminus of Helheim Glacier in winter, i.e. when melting at the glacier front is not enhanced by subglacial discharge, providing an independent validation of our technique. Variations in meltwater fluxes from icebergs are primarily related to differences in the submerged area of individual icebergs, which is consistent with theory. The stratification of water masses in fjords has a noticeable effect on summertime-derived melt estimates, with lower melt rates (and meltwater fluxes) observed in the relatively cold and fresh Polar Water layer and higher melt rates in the underlying warmer and more saline Atlantic Water layer. The meltwater flux dependence on submerged area, particularly within the deeper Atlantic Water layer, suggests that changes in the characteristics of icebergs (size/shape/keel-depth) calved from a tidewater glacier will alter the magnitude and distribution of meltwater fluxes within the fjord, which may in turn influence fjord circulation and the heat content delivered to the glacier terminus.

  11. Watershed Influences on Residence Time and Oxygen Reduction Rates in an Agricultural Landscape

    Science.gov (United States)

    Shope, C. L.; Tesoriero, A. J.

    2015-12-01

    Agricultural use of synthetic fertilizers and animal manure has led to increased crop production, but also elevated nitrogen concentrations in groundwater, resulting in impaired water quality. Groundwater oxygen concentrations are a key indicator of potential biogeochemical processes, which control water/aquifer interactions and contaminant transport. The U.S. Geological Survey's National Water-Quality Assessment Program has a long-history of studying nutrient transport and processing across the United States and the Glacial Aquifer system in particular. A series of groundwater well networks in Eastern Wisconsin is being used to evaluate the distribution of redox reaction rates over a range of scales with a focus on dissolved O2 reduction rates. An analysis of these multi-scale networks elucidates the influence of explanatory variables (i.e.: soil type, land use classification) on reduction rates and redox reactions throughout the Fox-Wolf-Peshtigo watersheds. Multiple tracers including dissolved gasses, tritium, helium, chlorofluorocarbons, sulfur hexafluoride, and carbon-14 were used to estimate groundwater ages (0.8 to 61.2 yr) at over 300 locations. Our results indicate O2 reduction rates along a flowpath study area (1.2 km2) of 0.15 mg O2 L-1 yr-1 (0.12 to 0.18 mg O2 L-1 yr-1) up to 0.41 mg O2 L-1 yr-1 (0.23 to 0.89 mg O2 L-1 yr-1) for a larger scale land use study area (3,300 km2). Preliminary explanatory variables that can be used to describe the variability in reduction rates include soil type (hydrologic group, bulk density) and chemical concentrations (nitrite plus nitrate, silica). The median residence time expected to reach suboxic conditions (≤ 0.4 mg O2 L-1) for the flowpath and the land use study areas was 66 and 25 yr, respectively. These results can be used to elucidate and differentiate the impact of residence time on groundwater quality vulnerability and sustainability in agricultural regions without complex flow models.

  12. Does a retrograde pyelography prior to ureteroscopy influence stone-free rates and complication rates in ureteral calculi?

    Science.gov (United States)

    Seklehner, Stephan; Heißler, Ortwin; Engelhardt, Paul F; Riedl, Claus

    2015-01-01

    To evaluate the impact of retrograde pyelography (RPG) in patients treated with ureteroscopy (URS) for ureteral calculi. Retrospective analysis of patients treated with and without RPG prior to URS at a single institution from 2010 to 2013. Assessment of stone-free rates and intraoperative complications. Out of 469 URS, 211 (45%) were done with and 258 (55%) without RPG. Complete stone removal was achieved in 86.8% without RPG compared to 73% with RPG (p=0.0001). Partial stone removal rates were similar in both groups (p=0.77). Stone removal was not achieved in 9.3 vs. 22.7% (p=0.0001), with concordant findings in the distal (7.4 vs. 16.9%, p=0.007) and the proximal ureter (14.5 vs. 38.6%, p=0.002). Patients with RPG had a threefold higher chance of an unsuccessful URS (OR 3.05, 1.71-5.43, pRPG prior to URS had significantly inferior stone-free rates. RPG was identified as an independent risk factor for inferior results. RPG neither facilitates nor diminishes complication rates during URS. © 2014 S. Karger AG, Basel.

  13. An investigation into the influence of drug-polymer interactions on the miscibility, processability and structure of polyvinylpyrrolidone-based hot melt extrusion formulations.

    Science.gov (United States)

    Chan, Siok-Yee; Qi, Sheng; Craig, Duncan Q M

    2015-12-30

    While hot melt extrusion is now established within the pharmaceutical industry, the prediction of miscibility, processability and structural stability remains a pertinent issue, including the issue of whether molecular interaction is necessary for suitable performance. Here we integrate the use of theoretical and experimental drug-polymer interaction assessment with determination of processability and structure of dispersions in two polyvinylpyrrolidone-based polymers (PVP and PVP vinyl acetate, PVPVA). Caffeine and paracetamol were chosen as model drugs on the basis of their differing hydrogen bonding potential with PVP. Solubility parameter and interaction parameter calculations predicted a greater miscibility for paracetamol, while ATR-FTIR confirmed the hydrogen bonding propensity of the paracetamol with both polymers, with little interaction detected for caffeine. PVP was found to exhibit greater interaction and miscibility with paracetamol than did PVPVA. It was noted that lower processing temperatures (circa 40°C below the Tg of the polymer alone and Tm of the crystalline drug) and higher drug loadings with associated molecular dispersion up to 50% w/w were possible for the paracetamol dispersions, although molecular dispersion with the non-interactive caffeine was noted at loadings up to 20% w./w. A lower processing temperature was also noted for caffeine-loaded systems despite the absence of detectable interactions. The study has therefore indicated that theoretical and experimental detection of miscibility and drug-polymer interactions may lead to insights into product processing and extrudate structure, with direct molecular interaction representing a helpful but not essential aspect of drug-polymer combination prediction.

  14. Influence of confinement on the orientational phase transitions in the lamellar phase of a block-copolymer melt under shear flow

    NARCIS (Netherlands)

    Morozov, AN; Zvelindovsky, AV; Fraaije, JGEM

    2001-01-01

    In this paper, we incorporate some real-system effects into the theory of orientational phase transitions under shear flow [M. E. Cates and S. T. Milner, Phys. Rev. Lett. 62 1856 (1989) and G. H. Fredrickson, J. Rheol. 38, 1045 (1994)]. In particular, we study the influence of the shear-cell

  15. 热熔压敏胶性能与药物释放速率的关系研究%Study on relationship of properties and drug release rate of hot melt pressure sensitive adhesive

    Institute of Scientific and Technical Information of China (English)

    俞振伟; 梁漪; 梁文权

    2011-01-01

    Objective: To investigate the relationship of properties and drug release rate of hot melt pressure sensitive adhesive ( HMPSA) , and to provide a recommendation of preparing and selecting of HMPSA for transdermal use. Method; HMPSA with different properties were prepared using styrene-isoprene-styrene triblock copolymer as main material, and the tacks, adhesions and cohesions were determined. Drug-in-adhesive type patches were prepared using α-asarone as model drug, and the drug release rates were investigated on single chamber diffusion cells using 60% ethanol solution as release media. Result; The prepared HMPSAs had different tacks, adhesions and cohesions. The drug release rates of HMPSA patches were related to the cohesions. The release rate decreased when the cohesion increased. Conclusion; The HMPSA with appropriate cohesion should be selected when preparing patches to balance the drug release rate and patch property.%目的:研究热熔压敏胶的性能与药物释放速率的关系,为经皮给药制剂用热熔压敏胶的制备与选择提供参考.方法:以苯乙烯-异戊二烯-苯乙烯三嵌段共聚物为主体材料制备了多种不同性能的热熔压敏胶,测定其初黏力、黏合力与内聚力;以α-细辛醚为模型药物制备各热熔压敏胶的胶黏分散型贴剂,以60%乙醇溶液为释放介质,于单室扩散池中测定药物的释放.结果:制备得到的热熔压敏胶具有不同的初黏力、黏合力与内聚力;热熔压敏胶贴剂的释放速率与热熔压敏胶的内聚力相关,内聚力越大,药物的释放速率就越慢.结论:制备贴剂时需选择内聚力适宜的热熔压敏胶,以达到药物释放速率和贴剂内聚力的平衡.

  16. Changes in acceleration rate of chloride ions depending on climatic conditions. Influence of rain

    Directory of Open Access Journals (Sweden)

    Corvo, F.

    2003-12-01

    Full Text Available Mild steel, copper and aluminium samples were exposed outdoors in two atmospheric test stations located in Havana, Cuba and Medellín, Colombia. Two parallel group of samples were formed, one for each station. They were submitted to accelerated outdoor test by intermittent spraying of a salt solution (SCAB test according to ISO 11474:98, receiving also the influence of the open atmosphere. The acceleration of corrosion rate of the three metals caused by the presence of chloride ions in both stations was determined. As expected, steel shows the higher corrosion rate and acceleration by chlorides, particularly at Cuban corrosion station. A remarkable difference in the acceleration rate of chloride ions for mild steel and copper between Cuban and Colombian acceleration rate of chloride ions of steel and copper. Steel corrosion products were analyzed by Mössbauer Spectroscopy. Water absorption was also studied. The presence of magnetite, goethite and other Iron compounds was determined.

    Probetas de acero de bajo carbono, cobre y aluminio se expusieron a la intemperie en dos estaciones de ensayo localizadas en la Habana, Cuba y Medellín, Colombia. Se formaron dos grupos paralelos de probetas, tomándose uno para cada estación. Ambos grupos fueron sometidos a ensayos acelerados a la intemperie mediante la aplicación de una niebla salina (SCAB TEST de acuerdo a la Norma ISO 11474:98, recibiendo también la influencia de la atmósfera abierta. Se determinó la aceleración de la velocidad de corrosión de los tres metales causada por la presencia de iones cloruro en ambas estaciones. Como era de esperar, el acero muestra la mayor velocidad de corrosión y aceleración por los iones cloruro, particularmente en la estación de ensayos cubana. Se determinó una notable diferencia en la velocidad de aceleración provocada por los cloruros para el acero de bajo carbono y el cobre entre las estaciones cubana y colombiana. La influencia de la lluvia

  17. Viscosity model for aluminosilicate melt

    Directory of Open Access Journals (Sweden)

    Zhang G.H.

    2012-01-01

    Full Text Available The structurally based viscosity model proposed in our previous study is extended to include more components, e.g. SiO2, Al2O3, FeO, MnO, MgO, CaO, Na2O and K2O. A simple method is proposed to calculate the numbers of different types of oxygen ions classified by the different cations they bonded with, which is used to characterize the influence of composition on viscosity. When dealing with the aluminosilicate melts containing several basic oxides, the priority order is established for different cations for charge compensating Al3+ ions, according to the coulombic force between cation and oxygen anion. It is indicated that basic oxides have two paradox influences on viscosity: basic oxide with a higher basicity decreases viscosity more greatly by forming weaker non-bridging oxygen bond; while it increases viscosity more greatly by forming stronger bridging oxygen bond in tetrahedron after charge compensating Al3+ ion. The present model can extrapolate its application range to the system without SiO2. Furthermore, it could also give a satisfy interpretation to the abnormal phenomenon that viscosity increases when adding K2O to CaO-Al2O3-SiO2 melt within a certain composition range.

  18. Sea ice breakup and marine melt of a retreating tidewater outlet glacier in northeast Greenland (81°N)

    DEFF Research Database (Denmark)

    Bendtsen, Jørgen; Mortensen, John; Lennert, Kunuk

    2017-01-01

    Rising temperatures in the Arctic cause accelerated mass loss from the Greenland Ice Sheet and reduced sea ice cover. Tidewater outlet glaciers represent direct connections between glaciers and the ocean where melt rates at the ice-ocean interface are influenced by ocean temperature and circulation...... glacier is a floating ice shelf with near-glacial subsurface temperatures at the freezing point. Melting from the surface layer significantly influenced the ice foot morphology of the glacier terminus. Hence, melting of the tidewater outlet glacier was found to be critically dependent on the retreat....... However, few measurements exist near outlet glaciers from the northern coast towards the Arctic Ocean that has remained nearly permanently ice covered. Here we present hydrographic measurements along the terminus of a major retreating tidewater outlet glacier from Flade Isblink Ice Cap. We show...

  19. Sea ice breakup and marine melt of a retreating tidewater outlet glacier in northeast Greenland (81 degrees N)

    DEFF Research Database (Denmark)

    Bendtsen, Jorgen; Mortensen, John; Lennert, Kunuk

    2017-01-01

    Rising temperatures in the Arctic cause accelerated mass loss from the Greenland Ice Sheet and reduced sea ice cover. Tidewater outlet glaciers represent direct connections between glaciers and the ocean where melt rates at the ice-ocean interface are influenced by ocean temperature and circulation...... glacier is a floating ice shelf with near-glacial subsurface temperatures at the freezing point. Melting from the surface layer significantly influenced the ice foot morphology of the glacier terminus. Hence, melting of the tidewater outlet glacier was found to be critically dependent on the retreat....... However, few measurements exist near outlet glaciers from the northern coast towards the Arctic Ocean that has remained nearly permanently ice covered. Here we present hydrographic measurements along the terminus of a major retreating tidewater outlet glacier from Flade Isblink Ice Cap. We show...

  20. Some influences of rock strength and strain rate on propagation of rock avalanches

    Science.gov (United States)

    Bowman, Elisabeth; Rait, Kim

    2016-04-01

    Rock avalanches are extreme and destructive mass movements in which large volumes of rock (typically >1 million cubic metres) travel at high speeds, covering large distances, and the occurrence of which is highly unpredictable. The "size effect" in rock avalanches, whereby those with larger volumes produce greater spreading efficiency (as defined by an increase in normalised runout) or lower farboschung angle (defined as the tangent of the ratio of fall height to runout length), is well known. Studies have shown that rock strength is a controlling factor in the mobility of rock avalanches - that is, mass movements involving lower strength rock are generally found to produce greater mobility as evidenced by the spread of deposits or low farboschung angle. However, there are conflicting ideas as to how and why this influence is manifested. This paper discusses different theories of rock comminution in light of numerical simulations of rock clasts undergoing normal and shear induced loading, experimental work on rock avalanche behaviour, and dynamic fracture mechanics. In doing so, we introduce the idea of thresholds of strain rate for the production of dynamic fragmentation (as opposed to pseudo-static clast crushing) that are based, inter alia, on static rock strength. To do this, we refer to data from physical models using rock analogue materials, field data on chalk cliff collapses, and field statistics from documented rock avalanches. The roles of normal and shear loading and loading rate within a rock avalanche are examined numerically using 3D Discrete Element Method models of rock clasts loaded to failure. Results may help to reconcile the observations that large rock avalanches in stronger materials tend not to fragment as much as those in weaker materials and also possess lower mobility, while small cliff collapses (typically > 1000 cubic metres) in weak chalk can exhibit rock avalanche-like behaviour at much smaller volumes.

  1. Does higher income inequality adversely influence infant mortality rates? Reconciling descriptive patterns and recent research findings.

    Science.gov (United States)

    Siddiqi, Arjumand; Jones, Marcella K; Erwin, Paul Campbell

    2015-04-01

    As the struggle continues to explain the relatively high rates of infant mortality (IMR) exhibited in the United States, a renewed emphasis is being placed on the role of possible 'contextual' determinants. Cross-sectional and short time-series studies have found that higher income inequality is associated with higher IMR at the state level. Yet, descriptively, the longer-term trends in income inequality and in IMR seem to call such results into question. To assess whether, over the period 1990-2007, state-level income inequality is associated with state-level IMR; to examine whether the overall effect of income inequality on IMR over this period varies by state; to test whether the association between income inequality and IMR varies across this time period. IMR data--number of deaths per 1000 live births in a given state and year--were obtained from the U.S. Centers for Disease Control Wonder database. Income inequality was measured using the Gini coefficient, which varies from zero (complete equality) to 100 (complete inequality). Covariates included state-level poverty rate, median income, and proportion of high school graduates. Fixed and random effects regressions were conducted to test hypotheses. Fixed effects models suggested that, overall, during the period 1990-2007, income inequality was inversely associated with IMR (β = -0.07, SE (0.01)). Random effects models suggested that when the relationship was allowed to vary at the state-level, it remained inverse (β = -0.05, SE (0.01)). However, an interaction between income inequality and time suggested that, as time increased, the effect of income inequality had an increasingly positive association with total IMR (β = 0.009, SE (0.002)). The influence of state income inequality on IMR is dependent on time, which may proxy for time-dependent aspects of societal context.

  2. Influence of running stride frequency in heart rate variability analysis during treadmill exercise testing.

    Science.gov (United States)

    Bailón, Raquel; Garatachea, Nuria; de la Iglesia, Ignacio; Casajús, Jose Antonio; Laguna, Pablo

    2013-07-01

    The analysis and interpretation of heart rate variability (HRV) during exercise is challenging not only because of the nonstationary nature of exercise, the time-varying mean heart rate, and the fact that respiratory frequency exceeds 0.4 Hz, but there are also other factors, such as the component centered at the pedaling frequency observed in maximal cycling tests, which may confuse the interpretation of HRV analysis. The objectives of this study are to test the hypothesis that a component centered at the running stride frequency (SF) appears in the HRV of subjects during maximal treadmill exercise testing, and to study its influence in the interpretation of the low-frequency (LF) and high-frequency (HF) components of HRV during exercise. The HRV of 23 subjects during maximal treadmill exercise testing is analyzed. The instantaneous power of different HRV components is computed from the smoothed pseudo-Wigner-Ville distribution of the modulating signal assumed to carry information from the autonomic nervous system, which is estimated based on the time-varying integral pulse frequency modulation model. Besides the LF and HF components, the appearance is revealed of a component centered at the running SF as well as its aliases. The power associated with the SF component and its aliases represents 22±7% (median±median absolute deviation) of the total HRV power in all the subjects. Normalized LF power decreases as the exercise intensity increases, while normalized HF power increases. The power associated with the SF does not change significantly with exercise intensity. Consideration of the running SF component and its aliases is very important in HRV analysis since stride frequency aliases may overlap with LF and HF components.

  3. Influence of the energy dissipation rate in the discharge of a plasma synthetic jet actuator

    Energy Technology Data Exchange (ETDEWEB)

    Belinger, A; Cambronne, J P [Universite de Toulouse, UPS, INPT, LAPLACE - Laboratoire Plasma et Conversion d' Energie, 118 route de Narbonne, F-31062 Toulouse cedex 9 (France); Hardy, P; Barricau, P; Caruana, D, E-mail: daniel.caruana@onera.fr [ONERA Centre Midi-Pyrenees, Departement Modeles pour l' Aerodynamique et l' Energetique, BP74025, 2 avenue Edouard Belin, 31055 TOULOUSE CEDEX 4 (France)

    2011-09-14

    A promising actuator for high-speed flow control, referred to as a plasma synthetic jet (PSJ), is being studied by the DMAE department of the ONERA, and the Laplace laboratory of the CNRS, in France. This actuator was inspired by the 'sparkjet' device developed by the Johns Hopkins University Applied Physics Laboratory. The PSJ, which produces a synthetic jet with high exhaust velocities, no active mechanical components and no mass flow admission, holds the promise of enabling high-speed flows to be manipulated. With this high-velocity jet it is possible to reduce fluid phenomena such as transition and turbulence, thus making it possible to increase an aircraft's performance whilst at the same time reducing its environmental impact. A thermal plasma discharge was created in a micro-cavity, causing the gas to be expelled. It is relevant that the velocity and momentum depend on the energy dispersed by the electric discharge. To control the frequency and energy dispersed in the plasma, the Laplace laboratory has developed two high-voltage power supply systems. These allow two different types of discharge to be produced, with energy being supplied to the discharge in two different manners. In this paper, we focus on the impact of the power supply on the plasma synthetic jet, and in particular on the role of the rate of energy dissipation in the discharge. In order to estimate the influence of the power supply on the machinery of the actuator, specific experimental techniques were used to investigate the electrical (voltage, current), thermal (Infra-red camera) and aerodynamic (jet duration, isentropic pressure, jet velocity) characteristics. These data sets were used to determine which of the two power supplies was more effective, thus allowing us to reach several conclusions concerning the importance of the energy dissipation rate on the PSJ actuator.

  4. Stepwise magma migration and accumulation processes and their effect on extracted melt chemistry

    Directory of Open Access Journals (Sweden)

    Urtson, Kristjan

    2009-12-01

    Full Text Available Numerical and analogue models suggest that melt production, its segregation from the solid matrix and subsequent transport and accumulation are highly dynamic and stepwise processes exhibiting scale invariant patterns in both time and length scales, which is characteristic of self-organized critical systems. This phenomenon is also observed in migmatites at several localities, where the leucosome thickness statistics obey power laws. Stepwise melt transport and deformation-enhanced melt mobility affect melt production dynamics by determining the distribution of extracted melt batch sizes and residence times of melt pockets within the host rock, which in turn would influence the geochemistry of extracted melts. We introduce a numerical approach, which enables qualitative and quantitative assessment of the effects of stress-induced melt migration and accumulation on the chemistry of partial melts. The model suggests that apart from different sources and melting percentages, deformation can be an important factor in producing geochemical variations within and between intrusive/extrusive complexes.

  5. Influence of polyunsaturated fatty acids on blood pressure, resting heart rate and heart rate variability among French Polynesians.

    Science.gov (United States)

    Valera, Beatriz; Suhas, Edouard; Counil, Emilie; Poirier, Paul; Dewailly, Eric

    2014-01-01

    To analyze the associations between marine n-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP), resting heart rate (HR), and heart rate variability (HRV) in a population highly exposed to methylmercury through the diet. Concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in erythrocytes membranes were measured in 180 French Polynesian adults (≥18 years) residing in Tubuai, which is a community with a traditional lifestyle, or Papeete, which has a modern lifestyle. HRV was measured using a 2-hour ambulatory electrocardiogram (Holter). Resting HR and BP were measured using standardized protocols and pulse pressure (PP) was calculated as systolic BP - diastolic BP. The associations between n-3 PUFAs and the dependent variables were studied using simple and multiple linear regressions. Increasing DHA concentration was associated with lower resting HR (β = -2.57, p = 0.005) and diastolic BP (β = -1.96, p = 0.05) and higher HRV in multivariable models. Specifically, DHA was associated with high frequency (HF; β = 0.19, p = 0.02) and the square root of the mean squared differences of successive R-R intervals (difference between two consecutive R waves; rMSSD; β = 0.08, p = 0.03), which are specific indices of the parasympathetic activity of the autonomic nervous system. DHA was associated with lower BP and resting HR and higher HRV among French Polynesians who are also exposed to high methylmercury levels.

  6. Influence of pH and temperature on alunite dissolution rates and products

    Science.gov (United States)

    Acero, Patricia; Hudson-Edwards, Karen

    2015-04-01

    Aluminium is one of the main elements in most mining-affected environments, where it may influence the mobility of other elements and play a key role on pH buffering. Moreover, high concentrations of Al can have severe effects on ecosystems and humans; Al intake, for example, has been implicated in neurological pathologies (e.g., Alzheimer's disease; Flaten, 2001). The behaviour of Al in mining-affected environments is commonly determined, at least partially, by the dissolution of Al sulphate minerals and particularly by the dissolution of alunite (KAl3(SO4)2(OH)6), which is one of the most important and ubiquitous Al sulphates in mining-affected environments (Nordstrom, 2011). The presence of alunite has been described in other acid sulphate environments, including some soils (Prietzel & Hirsch, 1998) and on the surface of Mars (Swayze et al., 2008). Despite the important role of alunite, its dissolution rates and products, and their controlling factors under conditions similar to those found in these environments, remain largely unknown. In this work, batch dissolution experiments have been carried out in order to shed light on the rates, products and controlling factors of alunite dissolution under different pH conditions (between 3 and 8) and temperatures (between 279 and 313K) similar to those encountered in natural systems. The obtained initial dissolution rates using synthetic alunite, based on the evolution of K concentrations, are between 10-9.7 and 10-10.9 mol-m-2-s-1, with the lowest rates obtained at around pH 4.8, and increases in the rates recorded with both increases and decreases in pH. Increases of temperature in the studied range also cause increases in the dissolution rates. The dissolution of alunite dissolution is incongruent, as has been reported for jarosite (isostructural with alunite) by Welch et al. (2008). Compared with the stoichiometric ratio in the bulk alunite (Al/K=3), K tends to be released to the solution preferentially over Al

  7. Influence of Loading Rate on the Calibration of Instrumented Charpy Strikers

    Energy Technology Data Exchange (ETDEWEB)

    Lucon, E.; Scibetta, M.; McColskey, D.; McCowan, C.

    2009-01-15

    One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. The conventional approach for establishing an analytical relationship between strain gage output and force applied to the transducer is the static calibration, which is preferably performed with the striker installed in the pendulum assembly. However, the response of an instrumented striker under static force application may sometimes differ significantly from its dynamic performance during an actual Charpy test. This is typically reflected in a large difference between absorbed energy returned by the pendulum encoder (KV) and calculated under the instrumented force/displacement test record (Wt). Such difference can be either minimized by optimizing the striker design or analytically removed by adjusting forces and displacements until KV = Wt (the so-called 'Dynamic Force Adjustment'). This study investigates the influence of increasing force application rates on the force/voltage characteristics of two instrumented strikers, one at NIST in Boulder, CO and one at SCK-CEN in Mol, Belgium.

  8. The influence of flow rate on inter-nucleation site heat transport

    Directory of Open Access Journals (Sweden)

    Baltis Coen

    2014-01-01

    Full Text Available The main topic of this paper is the influence of vertically aligned nucleation sites on each other in upward flow boiling. A setup was constructed to facilitate vertical up-flow of deminiralized water under saturation conditions. The main test section is a glass channel with a set of vertically aligned bubble generators. Each bubble generator is operated independently, where power and wall temperature are registered and the vapour bubbles are visualized by a high-speed camera. During the experiments, the downstream bubble generator (BG1 power is kept constant, while the power fed to the upstream bubble generator (BG2 is incrementally increased. Two main trends have been identified. The first trend is dominated by added convection from one site to the other. Both bubble frequency and detachment diameter on BG1 increase with increased power fed to upstream BG2. This effect decreases with increasing inter-site distance and becomes more significant with increasing liquid flow rate. When vapor bubbles start nucleating from BG2, these vapor bubbles inhibit bubble nucleation BG1 and can even lead to deactivation of this nucleation site. This second trend is only weakly dependent on inter-site distance, since the inhibition originates from bubbles flowing past BG1 in close proximity.

  9. Expression of anion exchanger 3 influences respiratory rate in awake and isoflurane anesthetized mice.

    Science.gov (United States)

    Meier, S; Hübner, C A; Groeben, H; Peters, J; Bingmann, D; Wiemann, M

    2007-11-01

    The anion exchanger 3 (AE3) is involved in neuronal pH regulation of which may include chemosensitive neurons. Here we examined the effect of AE3 expression on respiratory rate (RR) in vivo. AE3 knockout (KO, n=5) and wild type (WT, n=6) mice were subjected to body plethysmography, both while awake and during isoflurane anesthesia. RR was significantly lower in awake AE3 KO (162+/-7SE min(-1)) than in WT mice (212+/-20 min(-1), P=0.036). The same was found during isoflurane anesthesia at 0.5 MAC (KO: 123+/-9 min(-1), WT: 168+/-15 min(-1), P=0.026) and 1.0 MAC (KO: 51+/-6 min(-1), WT: 94+/-6 min(-1), P=0.001). Hypercapnia (5% CO2) increased RR in awake and decreased RR in nesthetized (1.0 MAC) mice, whereby relative changes were larger in AE3 KO mice. Recovery from isoflurane anesthesia in respect to RR regaining baseline values was more pronounced in AE3 KO. Results show that AE3 expression profoundly influences control of breathing in mice.

  10. Microbial consortium influence upon steel corrosion rate, using polarisation resistance and electrochemical noise techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Gayosso, M.J.; Zavala Olivares, G.; Ruiz Ordaz, N.; Juarez Ramirez, C.; Garcia Esquivel, R.; Padilla Viveros, A

    2004-10-01

    The microbiologically influenced corrosion (MIC) is a process, which affects the oil industry, particularly the hydrocarbons extraction, transport and storage. MIC evaluation has been normally based upon microbiological tests, and just a few references mention alternating methods, such as the electrochemical techniques, which can be used as criteria for their evaluation. In this work, two different electrochemical laboratory techniques, polarisation resistance and electrochemical noise were used, in order to determine the corrosion behaviour of a microbial consortium, obtained from a gas transporting pipeline, located in the southeast of Mexico. The bacteria population growth was found to be different for sessile and plancktonic microorganisms. Moreover, long incubation times were required to reach the maximum concentration of sessile bacteria. The electrochemical techniques used in this study exhibited a similar tendency on the corrosion rate behaviour with time, and values above 0.3 mm year{sup -1} were observed at the end of the experiments. The experiments were complemented with surface analysis. Scanning electron microscope observation of APIXL52 steel coupons, exposed to the consortium action, revealed bacteria presence, as well as a damaged steel surface. A type of localized corrosion was observed on the metal surface, and it was associated to the bacteria effect.

  11. Does chronic occupational exposure to volatile anesthetic agents influence the rate of neutrophil apoptosis?

    LENUS (Irish Health Repository)

    Goto, Y

    2012-02-03

    PURPOSE: The purpose of this preliminary investigation was to determine whether the rate of neutrophil apoptosis in health care workers is influenced by exposure to volatile anesthetic agents. METHODS: Percentage neutrophil apoptosis (Annexin-V FITC assay) was measured in health care workers (n = 20) and unexposed volunteers (n = 10). For the health care workers, time weighted personal exposure monitoring to N2O, sevoflurane and isoflurane was carried out. RESULTS: The sevoflurane and isoflurane concentrations to which health care workers were exposed were less than recommended levels in all 20 cases. Percent apoptosis was less at 24 (but not at one and 12) hr culture in health care workers [50.5 (9.7)%; P = 0.008] than in unexposed volunteers [57.3 (5.1)%]. CONCLUSION: Inhibition of neutrophil apoptosis at 24 hr culture was demonstrated in health care workers chronically exposed to volatile anesthetic agents. Exposure was well below recommended levels in the both scavenged and unscavenged work areas in which the study was carried out. Further study is required to assess the effect of greater degrees of chronic exposure to volatile anesthetic agents on neutrophil apoptosis.

  12. Contribution of snow and glacier melt to discharge for highly glacierised catchments in Norway

    Science.gov (United States)

    Engelhardt, M.; Schuler, T. V.; Andreassen, L. M.

    2014-02-01

    Glacierised catchments show a discharge regime that is strongly influenced by snow and glacier meltwaters. In this study, we modelled the mass balance and discharge rates for three highly glacierised catchments (>50% glacier cover) in western Norway over the period 1961-2012. The spatial pattern of the catchments follows a gradient in climate continentality from west to east. The model input were gridded temperature and precipitation values from seNorge (http://senorge.no) which are available at daily resolution. The model accounted for accumulation of snow, transformation of snow to firn and ice, evaporation and melt. Calibration and validation were performed for each catchment based on measurements of seasonal glacier mass balances and daily discharge rates, as additional validation data served daily melt rates from sonic rangers located in the ablation zones of two of the glaciers. The discharge sources snowmelt, glacier melt and rain were analysed with respect to spatial variations and temporal evolution. Model simulations reveal an increase in the relative contribution from glacier melt to total discharge for the three catchments from less than 10% in the early 1990s to 15-30% in the late 2000s. The decline in precipitation by 10-20% in the same period was therefore overcompensated, resulting in an increase in annual discharge by 5-20%. Annual discharge sums and annual glacier melt are most strongly correlated with annual and winter precipitation at the most maritime glacier and, with increased climate continentality, variations in both glacier melt contribution and annual discharge are becoming more strongly correlated with variations in summer temperatures. Therefore, glaciers in more continental climates are especially vulnerable to decrease in both annual and summer discharge with continued rise in summer temperatures and subsequent decrease in glacier extent. This may lead to significant changes to the discharge regime, with increase during spring but

  13. Nonlinear response of iceberg side melting to ocean currents

    Science.gov (United States)

    FitzMaurice, A.; Cenedese, C.; Straneo, F.

    2017-06-01

    Icebergs calving into Greenlandic Fjords frequently experience strongly sheared flows over their draft, but the impact of this flow past the iceberg is not fully captured by existing parameterizations. We present a series of novel laboratory experiments to determine the dependence of submarine melting along iceberg sides on a background flow. We show, for the first time, that two distinct regimes of melting exist depending on the flow magnitude and consequent behavior of melt plumes (side-attached or side-detached), with correspondingly different meltwater spreading characteristics. When this velocity dependence is included in melt parameterizations, melt rates estimated for observed icebergs in the attached regime increase, consistent with observed iceberg submarine melt rates. We show that both attached and detached plume regimes are relevant to icebergs observed in a Greenland fjord. Further, depending on the regime, iceberg meltwater may either be confined to a surface layer or distributed over the iceberg draft.

  14. Influences of nitrogen fertilizer application rates on radish yield, nutrition quality, and nitrogen recovery efficiency

    Institute of Scientific and Technical Information of China (English)

    Yulin LIAO; Xiangmin RONG; Shengxian ZHENG; Qiang LIU; Meirong FAN; Jianwei PENG; Guixian XIE

    2009-01-01

    Radishes (Raphanus sativus L.) were grown in plastic pots in a screenhouse to investigate the influences of nitrogen fertilizer application rates (NFAR) on yield, nitrate content, nitrate reductase activity (NR), nutrition quality, and nitrogen recovery efficiency (NRE) at commercial mature stage. Five N-rate treatments, 0.644, 0.819, 0.995, 1.170, and 1.346 g·por-1, were set up in the screenhouse pot experiments, and nitrogen fertilizer (unlabeled N and l5N-labeled fertilizer) was applied as basal dressing and topdressing, respectively. The results indicated that the fresh and dry weight yields of radish increased with the increase of NFAR at the range of 0.099 to 0.180g N-kg-1 soil, decreased at 0.207 g N-kg-1 soil, and accordingly there was a significant quadratic relationship between the fresh and dry weight yields of radish and the NFAR. At the high addition of urea-N fertilizer, the nitrate content accumulated in the fleshy roots and leaves due to the decline in NR activity. From 0.644 to 0.819 g N-por1 NR increased most rapidly, the highest NR activity occurred at 0.819 g N-por-1, and the lowest NR activity happened at 1.346 g N-por-1. Soluble sugar and ascorbic acid initially increased to the highest value and then decreased, and, contrarily, crude fiber rapidly decreased with the increase of NFAR. Total N uptake (TNU), N derived from fertilizer (Ndff), and N derived from soil (Ndfs) in radish increased, except that Ndfs relatively and slightly decreased at the rate of 0.207 g N-kg'soil. The ratio of Ndff to TNU increased, but the ratio of Ndfs to TNU as well as NRE of N fertilizer decreased with the increase of NFAR. Therefore, the appropriate NFAR should be preferably recommended for improving the yields and nutrition qualities of radish and NRE of N fertilizer.

  15. The rate of force generation by the myocardium is not influenced by afterload

    Directory of Open Access Journals (Sweden)

    Fioretto J.R.

    1997-01-01

    Full Text Available The influence of afterload on the rate of force generation by the myocardium was investigated using two types of preparations: the in situ dog heart (dP/dt and isolated papillary muscle of rats (dT/dt. Thirteen anesthetized, mechanically ventilated and thoracotomized dogs were submitted to pharmacological autonomic blockade (3.0 mg/kg oxprenolol plus 0.5 mg/kg atropine. A reservoir connected to the left atrium permitted the control of left ventricular end-diastolic pressure (LVEDP. A mechanical constriction of the descending thoracic aorta allowed to increase the systolic pressure in two steps of 20 mmHg (conditions H1 and H2 above control values (condition C. After arterial pressure elevations (systolic pressure C: 119 ± 8.1; H1: 142 ± 7.9; H2 166 ± 7.7 mmHg; P<0.01, there were no significant differences in heart rate (C: 125 ± 13.9; H1: 125 ± 13.5; H2: 123 ± 14.1 bpm; P>0.05 or LVEDP (C: 6.2 ± 2.48; H1: 6.3 ± 2.43; H2: 6.1 ± 2.51 mmHg; P>0.05. The values of dP/dt did not change after each elevation of arterial pressure (C: 3,068 ± 1,057; H1: 3,112 ± 996; H2: 3,086 ± 980 mmHg/s; P>0.05. In isolated rat papillary muscle, an afterload corresponding to 50% and 75% of the maximal developed tension did not alter the values of the maximum rate of tension development (100%: 78 ± 13; 75%: 80 ± 13; 50%: 79 ± 11 g mm-2 s-1, P>0.05. The results show that the rise in afterload per se does not cause changes in dP/dt or dT/dt

  16. Manufacturing laser glass by continuous melting

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J H; Suratwala, T; krenitsky, S; Takeuchi, K

    2000-07-01

    A novel, continuous melting process is being used to manufacture meter-sized plates of laser glass at a rate 20-times faster, 5-times cheaper, and with 2-3 times better optical quality than with previous one-at-a-time, ''discontinuous'' technology processes. This new technology for manufacturing laser glass, which is arguably the most difficult continuously-melted optical material ever produced, comes as a result of a $60 million, six-year joint R&D program between government and industry. The glasses manufactured by the new continuous melting process are Nd-doped phosphate-based glasses and are marketed under the product names LG-770 (Schott Glass Technologies) and LHG-8 (Hoya Corporation USA). With this advance in glass manufacturing technology, it is now possible to construct high-energy, high-peak-power lasers for use in fusion energy development, national defense, and basic physics research that would have been impractical to build using the old melting technology. The development of continuously melted laser glass required technological advances that have lead to improvements in the manufacture of other optical glass products as well. For example, advances in forming, annealing, and conditioning steps of the laser glass continuous melting process are now being used in manufacture of other large-size optical glasses.

  17. Influence of high-strain rate and temperature on the mechanical behavior of Nl-, Fe-, and Ti- based aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Gray, G.T. III

    1996-09-01

    The majority of the strength characterization studies on ordered intermetallics have concentrated on the assessment of strength and work-hardening at conventional strain rates. Although the influence of strain rate on the structure/property relationships of pure nickel, iron, and titanium and a variety of their alloys have been extensively studied, the effect of strain rate on the stress-strain response of Ni-, Fe-, and Ti-based aluminides remains poorly understood. Dynamic constitutive behavior is however relevant to high speed impact performance of these materials such as during foreign object damage in aerospace applications, high-rate forging, and localized deformation behavior during machining. The influence of strain rate, varied between 0.001 and 10{sup 4} s{sup -1}, and temperatures, between 77 & 800K, on the compressive mechanical behavior of Ni{sub 3}A1, NiAl, Fe{sub 3}Al, Fe-40Al-0.1B, Ti-24Al-11Nb, and Ti-48Al-2Cr-2Nb will be presented. In this paper the influence of strain rate on the anomalous temperature dependency of the flow stresses in these aluminides will be reviewed and compared between aluminides. The rate sensitivity and work hardening of each aluminide will be discussed as a function of strain rate and temperature and contrasted to each other and to the values typical for their respective disordered base metals. 66 refs., 16 figs., 2 tabs.

  18. Segment-Scale Melt Extraction at Mid-Ocean Ridges: A Play in Three Acts

    Science.gov (United States)

    Montesi, L. G.; Hebert, L. B.; Behn, M. D.

    2011-12-01

    At mid-ocean ridges, the lithosphere is created through a combination of melt extraction, metasomatism, and cooling, and the oceanic crust forms as melt collects near the surface. As the presence of melt also has rheological and geochemical consequences, a better understanding of the mechanisms that control melt migration and extraction at mid-ocean ridges is necessary to constrain the processes that form oceanic lithosphere and plate boundaries. Melt migration is described rigorously by two-phase transport equations in porous or fractured media. However, scaling considerations and geological constraints typically lead to certain simplifications when incorporated into geodynamical models. It is possible to capture the essence of melt migration and extraction by considering three principal stages: Stage 1. Vertical migration: Melt is generated by adiabatic decompression and rises nearly vertically from the zone of melt production to a melt-impermeable boundary, or permeability barrier, at the base of the thermal lithosphere. Stage 2. Focusing: Melt travels along a permeability barrier. The barrier is associated with a crystallization front and is slightly inclined toward the ridge axis following the thermal structure of the plate. At this stage melt focusing occurs toward and along the strike of the ridge. Stage 3. Extraction: Melt enters a melt extraction zone (MEZ) and is extracted to the surface. The MEZ represents the combined effect of faults and/or dikes that promote rapid lateral and vertical melt migration and eventual eruption on the seafloor. Stage 1 is expected based on scaling arguments of buoyancy and permeability [e.g., Zhu et al., Science, 2011]. Stages 2 and 3 are directly influenced by the structure of the lithosphere, which is itself controlled by the segmentation of the ridge axis, spreading rate, and mantle potential temperature. Thus, it is possible to use along-strike variations in melt delivery in well-studied geological settings to constrain

  19. Influence of grooming on Rhipicephalus microplus tick infestation and serum cortisol rates

    Directory of Open Access Journals (Sweden)

    Fernanda Ferreira Pessoa

    2012-12-01

    Full Text Available Grooming is an important factor on animal resistance to ticks. Rhipicephalus microplus is the most pathogenic cattle tick in Brazil causing death in susceptible animals. Cortisol is the hormone of stress. The influence of grooming on tick infestation and serum cortisol level was studied in 16 Holstein heifers from fifth to eight-month-old. They were infested with 10,000 larvae in June/20/2011. Half of them used a necklace made of wood strips and had an infestation chamber made by cotton cloth covering about 50 cm diameter of the shaved flank, fixed at the skin in both sides with adhesive to prevent larvae to escape from the infestation chamber and the amount of larvae was divided into the two chambers. Such artifacts had the purpose to avoid grooming. The heifers remained all the tick parasitic life cycle in individual pens inside a closed shed at Instituto de Zootecnia, in Nova Odessa, São Paulo State. Tick females bigger than 4.5 mm were counted in the right side from day 20 to 22 after the artificial infestation. The tick recovery rate was calculated by adding and multiplying by two the number of ticks counted, assuming that 5,000 female larvae had infested the cattle. Immediately before infestation (day 0 and in day2, day8, and day17 after infestation, blood samples were collected using vacuum tubes, in the morning (8:30 – 10:00 A.M.. Cortisol was measured by immunoassay (EIA and the D.O. (optical density at 420 nm was converted in ng of cortisol/mL of serum sample. The experimental design was randomized with 8 replications. Data from serum cortisol were analyzed using the General linear models of the SPSS® statistical package (version 12.0 using the presence of the artifacts (necklace and chamber and sampling day as independent variables and serum cortisol as the dependent variable. In the analyse of tick recovery rate, the presence of artifacts was the independent variable and tick recovery rate the dependent variable. The presence of

  20. Influence of early pregnancy on reproductive rate in lines of mice selected for litter size.

    Science.gov (United States)

    Eisen, E J

    1980-09-01

    The influence of male-induced early puberty on female reproductive rate was determined in three lines of mice differing in litter size and body weight. The lines originated from a single base population and had undergone 20 generations of selection for the following criteria: large litter size at birth (L(+)), large litter size and small 6-week body weight (L(+)W(-)), or small litter size and large 6-week body weight (L(-)W(+)). Females were paired with a mature intact male of the same line at 3, 5 or 7 weeks of age. Mean mating age, averaged over lines, was 26.5 ± .3, 38.3 ± .3 and 52.7 ± .3 days. Exposure to a mature male accelerated female sexual maturation in each line. When contrasted with their sibs mated at a later age, early-pregnant females from each line exhibited a decline in one or more component of reproductive performance, suggesting that the physiological state of the very young female was not optimum for normal pregnancy. In comparisons of early and later mating ages, all three lines showed a decreased littering rate at first mating, number born alive, and individual birth weight of progeny adjusted for litter size; L(+) and L(+)W(-) mice showed an increased perinatal mortality rate; L(+) and L(-)W(+) had a reduction in litter size at birth. When the L(+), L(+)W(-) and L(-)W(+) lines were compared with an unselected strain and a line selected for high postweaning gain in similar experiments, a genotype by environment interaction was apparent since all lines did not respond in a similar manner to early mating. The line ranking for litter size at birth for each age at male-exposure was L(+)>L(+)W(-)>L(-)W(+), despite the significant line by age interaction. When litter size was adjusted by covariance for body weight at mating, the significant effects of age at male-exposure and line by age interaction were eliminated. All fertile females were remated after they had weaned their first litter to obtain information on litter size in parity two. Line

  1. The Gao-Guenie impact melt breccia—Sampling a rapidly cooled impact melt dike on an H chondrite asteroid?

    Science.gov (United States)

    Schmieder, Martin; Kring, David A.; Swindle, Timothy D.; Bond, Jade C.; Moore, Carleton B.

    2016-06-01

    The Gao-Guenie H5 chondrite that fell on Burkina Faso (March 1960) has portions that were impact-melted on an H chondrite asteroid at ~300 Ma and, through later impact events in space, sent into an Earth-crossing orbit. This article presents a petrographic and electron microprobe analysis of a representative sample of the Gao-Guenie impact melt breccia consisting of a chondritic clast domain, quenched melt in contact with chondritic clasts, and an igneous-textured impact melt domain. Olivine is predominantly Fo80-82. The clast domain contains low-Ca pyroxene. Impact melt-grown pyroxene is commonly zoned from low-Ca pyroxene in cores to pigeonite and augite in rims. Metal-troilite orbs in the impact melt domain measure up to ~2 mm across. The cores of metal orbs in the impact melt domain contain ~7.9 wt% of Ni and are typically surrounded by taenite and Ni-rich troilite. The metallography of metal-troilite droplets suggest a stage I cooling rate of order 10 °C s-1 for the superheated impact melt. The subsolidus stage II cooling rate for the impact melt breccia could not be determined directly, but was presumably fast. An analogy between the Ni rim gradients in metal of the Gao-Guenie impact melt breccia and the impact-melted H6 chondrite Orvinio suggests similar cooling rates, probably on the order of ~5000-40,000 °C yr-1. A simple model of conductive heat transfer shows that the Gao-Guenie impact melt breccia may have formed in a melt injection dike ~0.5-5 m in width, generated during a sizeable impact event on the H chondrite parent asteroid.

  2. Intrinsic vs. extrinsic influences on life history expression: metabolism and parentally induced temperature influences on embryo development rate

    Science.gov (United States)

    Martin, Thomas E.; Ton, Riccardo; Nikilson, Alina

    2013-01-01

    Intrinsic processes are assumed to underlie life history expression and trade-offs, but extrinsic inputs are theorised to shift trait expression and mask trade-offs within species. Here, we explore application of this theory across species. We do this based on parentally induced embryo temperature as an extrinsic input, and mass-specific embryo metabolism as an intrinsic process, underlying embryonic development rate. We found that embryonic metabolism followed intrinsic allometry rules among 49 songbird species from temperate and tropical sites. Extrinsic inputs via parentally induced temperatures explained the majority of variation in development rates and masked a relationship with metabolism; metabolism explained a minor proportion of the variation in development rates among species, and only after accounting for temperature effects. We discuss evidence that temperature further obscures the expected interspecific trade-off between development rate and offspring quality. These results demonstrate the importance of considering extrinsic inputs to trait expression and trade-offs across species.

  3. Study of Contact Melting Inside Isothermally Heated Vertical Cylindrical Capsules

    Institute of Scientific and Technical Information of China (English)

    ChenWenzhen; ChengShangmo; 等

    1993-01-01

    Close-contact melting processes of phase change material(PCM) inside vertical cylindrical capsule are studied.PCM are heated bhy the capsule isothermalyy at the bottom and side.The theoretical formulas of the melting rate and thickness of liquid layer during the heat transfer process are obtained by analysis,which are convenient for engineering predictions.Finally,the factors that affect melting are discussed.and conclusions are drawn.

  4. Numerical analysis of fluid flow and heat transfer during melting inside a cylindrical container for thermal energy storage system

    Science.gov (United States)

    Bellan, Selvan; Cheok, Cho Hyun; Gokon, Nobuyuki; Matsubara, Koji; Kodama, Tatsuya

    2017-06-01

    This paper presents a numerical analysis of unconstrained melting of high temperature(>1000K) phase change material (PCM) inside a cylindrical container. Sodium chloride and Silicon carbide have been used as phase change material and shell of the capsule respectively. The control volume discretization approach has been used to solve the conservation equations of mass, momentum and energy. The enthalpy-porosity method has been used to track the solid-liquid interface of the PCM during melting process. Transient numerical simulations have been performed in order to study the influence of radius of the capsule and the Stefan number on the heat transfer rate. The simulation results show that the counter-clockwise Buoyancy driven convection over the top part of the solid PCM enhances the melting rate quite faster than the bottom part.

  5. Experimental observation of Minkowski spacetime melting

    CERN Document Server

    Smolyaninov, Igor I

    2015-01-01

    Cobalt nanoparticle-based ferrofluid in the presence of an external magnetic field forms a self-assembled hyperbolic metamaterial, which may be described as an effective 3D Minkowski spacetime for extraordinary photons. If the magnetic field is not strong enough, this effective Minkowski spacetime gradually melts under the influence of thermal fluctuations. On the other hand, it may restore itself if the magnetic field is increased back to its original value. Here we present direct microscopic visualization of such a Minkowski spacetime melting/crystallization, which is somewhat similar to hypothesized formation of the Minkowski spacetime in loop quantum cosmology.

  6. The influence of freezing rates on bovine pericardium tissue Freeze-drying

    Directory of Open Access Journals (Sweden)

    Camila Figueiredo Borgognoni

    2009-12-01

    Full Text Available The bovine pericardium has been used as biomaterial in developing bioprostheses. Freeze-drying is a drying process that could be used for heart valve's preservation. The maintenance of the characteristics of the biomaterial is important for a good heart valve performance. This paper describes the initial step in the development of a bovine pericardium tissue freeze-drying to be used in heart valves. Freeze-drying involves three steps: freezing, primary drying and secondary drying. The freezing step influences the ice crystal size and, consequently, the primary and secondary drying stages. The aim of this work was to investigate the influence of freezing rates on the bovine pericardium tissue freeze-drying parameters. The glass transition temperature and the structural behaviour of the lyophilized tissues were determined as also primary and secondary drying time. The slow freezing with thermal treatment presented better results than the other freeze-drying protocols.O pericárdio bovino é um material utilizado na fabricação de biopróteses. A liofilização é um método de secagem que vem sendo estudado para a conservação de válvulas cardíacas. A preservação das características do biomaterial é de fundamental importância no bom funcionamento das válvulas. Este artigo é a primeira etapa do desenvolvimento do ciclo de liofilização do pericárdio bovino. Liofilização é o processo de secagem no qual a água é removida do material congelado por sublimação e desorção da água incongelável, sob pressão reduzida. O congelamento influencia o tamanho do cristal de gelo e, consequentemente, a secagem primária e secundária. O objetivo deste estudo foi verificar a influência das taxas de congelamento nos parâmetros de liofilização do pericárdio bovino. Determinou-se a temperatura de transição vítrea e o comportamento estrutural do pericárdio bovino liofilizado. Determinou-se o tempo da secagem primária e secundária. O

  7. Cues of High and Low Body Weight Negatively Influence Adults' Perceptions and Ratings in the Hypothetical Adoption Paradigm

    Directory of Open Access Journals (Sweden)

    Anthony A. Volk

    2006-01-01

    Full Text Available Infant and child facial cues influence perceptions and ratings in the Hypothetical Adoption Paradigm as well as actual parental care. A previous study demonstrated that infant and child facial cues of low body weight negatively influenced adults' ratings. The current study sought to replicate and expand on those results by presenting adults with normal faces as well as faces that were digitally altered to display high or low body weight. Cues of abnormal body weight significantly, and negatively, influenced adults’ ratings of adoption preference, health, and cuteness. Effect sizes were larger for cues of high body weight. Thus, infant and child facial cues of abnormal body weight may represent a relative risk factor to the quality of adult care obtained by children with abnormal body weight.

  8. While Mortality Rates Differ After Dysvascular Partial Foot and Transtibial Amputation, Should They Influence the Choice of Amputation Level?

    Science.gov (United States)

    Dillon, Michael; Fatone, Stefania; Quigley, Matthew

    2017-09-01

    Although there is strong evidence to show that the risk of dying after transtibial amputation is higher than partial foot amputation, we are concerned by the implication that amputation level influences mortality, and that such interpretations of the evidence may be used to inform decisions about the choice of amputation level. We argue that the choice of partial foot or transtibial amputation does not influence the risk of mortality. The highest mortality rates are observed in studies with older people with more advanced systemic disease and multiple comorbidities. Studies that control for the confounding influence of these factors have shown no differences in mortality rates by amputation level. These insights have important implications in terms of how we help inform difficult decisions about amputation at either the partial foot or transtibial level, given a more thoughtful interpretation of the published mortality rates. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  9. GLASS MELTING PHENOMENA, THEIR ORDERING AND MELTING SPACE UTILISATION

    Directory of Open Access Journals (Sweden)

    Němec L.

    2013-12-01

    Full Text Available Four aspects of effective glass melting have been defined – namely the fast kinetics of partial melting phenomena, a consideration of the melting phenomena ordering, high utilisation of the melting space, and effective utilisation of the supplied energy. The relations were defined for the specific melting performance and specific energy consumption of the glass melting process which involve the four mentioned aspects of the process and indicate the potentials of effective melting. The quantity “space utilisation” has been treated in more detail as an aspect not considered in practice till this time. The space utilisation was quantitatively defined and its values have been determined for the industrial melting facility by mathematical modelling. The definitions of the specific melting performance and specific energy consumption have been used for assessment of the potential impact of a controlled melt flow and high space utilisation on the melting process efficiency on the industrial scale. The results have shown that even the partial control of the melt flow, leading to the partial increase of the space utilisation, may considerably increase the melting performance, whereas a decrease of the specific energy consumption was determined to be between 10 - 15 %.

  10. Fabricating and controlling PCL electrospun microfibers using filament feeding melt electrospinning technique

    Science.gov (United States)

    Ko, Junghyuk; Ahsani, Vahid; Xiangxiao Yao, Selina; Mohtaram, Nima K.; Lee, Patrick C.; Jun, Martin B. G.

    2017-02-01

    The process of melt electrospinning has received noteworthy attention due to its ability to fabricate micro scaled polymer fibers. Recently, a melt electrospinning process has been attracting attention for biomedical applications, in particular with scaffold fabrication for tissue engineering. In order to enhance cell attachment and proliferation on scaffolds, it is important to control fiber diameters to create an environment to which cells can attach, grow, and proliferate with ease. However, because electrospinning is a process with many parameters, it is particularly difficult to precisely control the diameter of the resulting fibers. Also, polymer powders or pellets melted in nozzles are typically used for melt electrospinning. However, a filament feeding melt electrospinning process has not been yet been implemented. In this study, we developed a melt electrospinning device which can feed PCL (Polycaprolactone, Mw: 80 000 g mol-1) filaments for advanced electrospun fiber diameter control. The PCL filaments were first fabricated by a small scale micro-compounder and then fed into the melting chamber of the electrospinning device. The system was then heated to a desired temperature, and the melt was extruded through a nozzle. The potential difference between the nozzle and counter electrode then drew down the PCL extrudate, creating fine microfibers. Temperature was controlled and monitored via a customized temperature control system. In order to control the dispensing of the PCL filaments, a customized control algorithm using NI (National Instruments) LabVIEW was used. In order to actively cool PCL filaments, a miniature computer fan was attached on the side of the melting chamber so that the filaments would not buckle. This paper reveals the investigation of significant process parameters that influence fiber diameters and their optimization. For instance, applied voltages, distances between the nozzle and a counter electrode, processing temperatures, and

  11. Influence of Rice Seeding Rate on Efficacies of Neonicotinoid and Anthranilic Diamide Seed Treatments against Rice Water Weevil

    Directory of Open Access Journals (Sweden)

    Jason Hamm

    2014-12-01

    Full Text Available Rice in the U.S. is frequently seeded at low rates and treated before sowing with neonicotinoid or anthranilic diamide insecticides to target the rice water weevil. A previous study of the influence of seeding rate on rice water weevil densities showed an inverse relationship between seeding rates and immature weevil densities. This study investigated interactive effects of seeding rate and seed treatment on weevil densities and rice yields; in particular, experiments were designed to determine whether seed treatments were less effective at low seeding rates. Four experiments were conducted over three years by varying seeding rates of rice treated at constant per seed rates of insecticide. Larval suppression by chlorantraniliprole was superior to thiamethoxam or clothianidin, and infestations at low seeding rates were up to 47% higher than at high seeding rates. Little evidence was found for the hypothesis that seed treatments are less effective at low seeding rates; in only one of four experiments was the reduction in weevil densities by thiamethoxam greater at high than at low seeding rates. However, suppression of larvae by neonicotinoid seed treatments in plots seeded at low rates was generally poor, and caution must be exercised when using the neonicotioids at low seeding rates.

  12. The influence of impaction on the rate of third molar mineralisation in male black Africans.

    Science.gov (United States)

    Olze, Andreas; van Niekerk, Piet; Schulz, Ronald; Ribbecke, Sebastian; Schmeling, Andreas

    2012-11-01

    One of the main criteria used in dental age diagnostics in living adolescents and young adults is assessment of the mineralisation stage of the third molars. In the case of Europid populations, it has been established that impaction status has an influence on the rate of mineralisation of the third molars. In view of this, a study was undertaken to determine whether the chronological process of wisdom tooth mineralisation is dependent upon impaction status in black Africans too. Orthopantomograms (553) of 437 male and 116 female black South Africans with verified birth dates in the age group between 10 and 26 years were studied. Mineralisation stage and impaction status were determined for all third molars. Statistical measures were calculated for the mandibular wisdom teeth at stages F, G and H and for the maxillary wisdom teeth at stage H in the male gender for both impacted and non-impacted third molars. It was ascertained that the minimum age in persons with impacted third molars, depending on the wisdom tooth observed, was 0.19-2.57 years higher than in those with non-impacted wisdom teeth. Test persons with impacted mandibular wisdom teeth at stage F or G were on average between 0.32 and 1.88 years older than those with non-impacted mandibular wisdom teeth. The 50 % probability values of impacted wisdom teeth at stage H were 1.85-3.31 years higher than those in non-impacted wisdom teeth. The conclusion was drawn that in male black Africans, impacted mandibular wisdom teeth mineralise more slowly than non-impacted lower third molars. The presence of impacted mandibular wisdom teeth in mineralisation stage H in male black Africans does not, however, furnish proof of completion of the 18(th) year of life beyond reasonable doubt.

  13. Influence of magnesium sulfate on HCO3/Cl transmembrane exchange rate in human erythrocytes.

    Science.gov (United States)

    Chernyshova, Ekaterina S; Zaikina, Yulia S; Tsvetovskaya, Galina A; Strokotov, Dmitry I; Yurkin, Maxim A; Serebrennikova, Elena S; Volkov, Leonid; Maltsev, Valeri P; Chernyshev, Andrei V

    2016-03-21

    Magnesium sulfate (MgSO4) is widely used in medicine bu