A Modified Constant-Stress Coupon for Enhanced Natural Crack Start during Fatigue Testing

DTIC Science & Technology

2016-05-01

improved numerically controlled manufacture. DSTO Research Report DSTO-RR-0340, July 2009. Wescott R, M Jones, M Heller. Stress analysis for design of...has been confirmed by Yu et al. (2014) through experimental strain measurement as well as fatigue tests under spectrum loading. However, as designed ...the results of analyses of a variety of typical non -optimal non -constant stress dog-bone coupon designs . One of those designs has in fact previously

Direct measurement of additional Ar-H2O vibration-rotation-tunneling bands in the millimeter-submillimeter range

NASA Astrophysics Data System (ADS)

Zou, Luyao; Widicus Weaver, Susanna L.

2016-06-01

Three new weak bands of the Ar-H2O vibration-rotation-tunneling spectrum have been measured in the millimeter wavelength range. These bands were predicted from combination differences based on previously measured bands in the submillimeter region. Two previously reported submillimeter bands were also remeasured with higher frequency resolution. These new measurements allow us to obtain accurate information on the Coriolis interaction between the 101 and 110 states. Here we report these results and the associated improved molecular constants.

The Gaseous Explosive Reaction : The Effect of Inert Gases

NASA Technical Reports Server (NTRS)

Stevens, F W

1928-01-01

Attention is called in this report to previous investigations of gaseous explosive reactions carried out under constant volume conditions, where the effect of inert gases on the thermodynamic equilibrium was determined. The advantage of constant pressure methods over those of constant volume as applied to studies of the gaseous explosive reaction is pointed out and the possibility of realizing for this purpose a constant pressure bomb mentioned. The application of constant pressure methods to the study of gaseous explosive reactions, made possible by the use of a constant pressure bomb, led to the discovery of an important kinetic relation connecting the rate of propagation of the zone of explosive reaction within the active gases, with the initial concentrations of those gases: s = K(sub 1)(A)(sup n1)(B)(sup n2)(C)(sup n3)------. By a method analogous to that followed in determining the effect of inert gases on the equilibrium constant K, the present paper records an attempt to determine their kinetic effect upon the expression given above.

Effect of the cosmological constant on the deflection angle by a rotating cosmic string

NASA Astrophysics Data System (ADS)

Jusufi, Kimet; Övgün, Ali

2018-03-01

We report the effect of the cosmological constant and the internal energy density of a cosmic string on the deflection angle of light in the spacetime of a rotating cosmic string with internal structure. We first revisit the deflection angle by a rotating cosmic string and then provide a generalization using the geodesic equations and the Gauss-Bonnet theorem. We show there is an agreement between the two methods when employing higher-order terms of the linear mass density of the cosmic string. By modifying the integration domain for the global conical topology, we resolve the inconsistency between these two methods previously reported in the literature. We show that the deflection angle is not affected by the rotation of the cosmic string; however, the cosmological constant Λ strongly affects the deflection angle, which generalizes the well-known result.

Elastic properties of sulphur and selenium doped ternary PbTe alloys by first principles

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

Bali, Ashoka, E-mail: rcmallik@physics.iisc.ernet.in; Chetty, Raju, E-mail: rcmallik@physics.iisc.ernet.in; Mallik, Ramesh Chandra, E-mail: rcmallik@physics.iisc.ernet.in

2014-04-24

Lead telluride (PbTe) is an established thermoelectric material which can be alloyed with sulphur and selenium to further enhance the thermoelectric properties. Here, a first principles study of ternary alloys PbS{sub x}Te{sub (1−x)} and PbSe{sub x}Te{sub (1−x)} (0≤x≤1) based on the Virtual Crystal Approximation (VCA) is presented for different ratios of the isoelectronic atoms in each series. Equilibrium lattice parameters and elastic constants have been calculated and compared with the reported data. Anisotropy parameter calculated from the stiffness constants showed a slight improvement in anisotropy of elastic properties of the alloys over undoped PbTe. Furthermore, the alloys satisfied the predictedmore » stability criteria from the elastic constants, showing stable structures, which agreed with the previously reported experimental results.« less

Estimation of Anaerobic Debromination Rate Constants of PBDE Pathways Using an Anaerobic Dehalogenation Model.

PubMed

Karakas, Filiz; Imamoglu, Ipek

2017-04-01

This study aims to estimate anaerobic debromination rate constants (k m ) of PBDE pathways using previously reported laboratory soil data. k m values of pathways are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model. Debromination activities published in the literature in terms of bromine substitutions as well as specific microorganisms and their combinations are used for identification of pathways. The range of estimated k m values is between 0.0003 and 0.0241 d -1 . The median and maximum of k m values are found to be comparable to the few available biologically confirmed rate constants published in the literature. The estimated k m values can be used as input to numerical fate and transport models for a better and more detailed investigation of the fate of individual PBDEs in contaminated sediments. Various remediation scenarios such as monitored natural attenuation or bioremediation with bioaugmentation can be handled in a more quantitative manner with the help of k m estimated in this study.

Detection of Hb Constant Spring [α142, Term→Gln, TAA>CAA (α2)] in heterozygotes combined with β-thalassemia.

PubMed

Li, You-Qiong; Li, Ru; Li, Dong-Zhi

2013-01-01

Hb Constant Spring [Hb CS, α142, Term→Gln, TAA>CAA (α2)] is a nondeletional form of α-thalassemia (α-thal) that is most prevalent in Southern Chinese and Southeast Asian populations. We previously found that Hb CS trait could efficiently be screened using Sebia Capillarys2. In this study, we report that Hb CS heterozygotes combined with β-thal could not be detected by the Sebia Capillarys2 method due to the very small amount of Hb CS.

The evolution of human phenotypic plasticity: age and nutritional status at maturity.

PubMed

Gage, Timothy B

2003-08-01

Several evolutionary optimal models of human plasticity in age and nutritional status at reproductive maturation are proposed and their dynamics examined. These models differ from previously published models because fertility is not assumed to be a function of body size or nutritional status. Further, the models are based on explicitly human demographic patterns, that is, model human life-tables, model human fertility tables, and, a nutrient flow-based model of maternal nutritional status. Infant survival (instead of fertility as in previous models) is assumed to be a function of maternal nutritional status. Two basic models are examined. In the first the cost of reproduction is assumed to be a constant proportion of total nutrient flow. In the second the cost of reproduction is constant for each birth. The constant proportion model predicts a negative slope of age and nutritional status at maturation. The constant cost per birth model predicts a positive slope of age and nutritional status at maturation. Either model can account for the secular decline in menarche observed over the last several centuries in Europe. A search of the growth literature failed to find definitive empirical documentation of human phenotypic plasticity in age and nutritional status at maturation. Most research strategies confound genetics with phenotypic plasticity. The one study that reports secular trends suggests a marginally insignificant, but positive slope. This view tends to support the constant cost per birth model.

Role of Cyclin D1 and cdk Inhibitors in Breast Cancer Pathogenesis

DTIC Science & Technology

2001-10-01

0.1 [tg of a Renilla luciferase expression plasmid (pRL-SV40 Promega) to normalize for transfection efficiency. After an overnight recovery, the...saline, collected, lysed, and analyzed for luciferase and Renilla luciferase activity by using the Dual-Luciferase reporter assay system (Promega...Cyclin A promoter-driven luciferase activity was then normalized to a constant activity of Renilla luciferase. 7 Results In our previous reports we

Linear free energy relationships between aqueous phase hydroxyl radical reaction rate constants and free energy of activation.

PubMed

Minakata, Daisuke; Crittenden, John

2011-04-15

The hydroxyl radical (HO(•)) is a strong oxidant that reacts with electron-rich sites on organic compounds and initiates complex radical chain reactions in aqueous phase advanced oxidation processes (AOPs). Computer based kinetic modeling requires a reaction pathway generator and predictions of associated reaction rate constants. Previously, we reported a reaction pathway generator that can enumerate the most important elementary reactions for aliphatic compounds. For the reaction rate constant predictor, we develop linear free energy relationships (LFERs) between aqueous phase literature-reported HO(•) reaction rate constants and theoretically calculated free energies of activation for H-atom abstraction from a C-H bond and HO(•) addition to alkenes. The theoretical method uses ab initio quantum mechanical calculations, Gaussian 1-3, for gas phase reactions and a solvation method, COSMO-RS theory, to estimate the impact of water. Theoretically calculated free energies of activation are found to be within approximately ±3 kcal/mol of experimental values. Considering errors that arise from quantum mechanical calculations and experiments, this should be within the acceptable errors. The established LFERs are used to predict the HO(•) reaction rate constants within a factor of 5 from the experimental values. This approach may be applied to other reaction mechanisms to establish a library of rate constant predictions for kinetic modeling of AOPs.

Rate of reaction of OH with HNO3

NASA Technical Reports Server (NTRS)

Wine, P. H.; Ravishankara, A. R.; Kreutter, N. M.; Shah, R. C.; Nicovich, J. M.; Thompson, R. L.; Wuebbles, D. J.

1981-01-01

Measurements of the kinetics of the reaction of OH with HNO3, and mechanisms of HNO3 removal from the stratosphere, are reported. Bimolecular rate constants were determined at temperatures between 224 and 366 K by monitoring the concentrations of OH radicals produced by HNO3 photolysis and HNO3 according to their resonance fluorescence and 184.9-nm absorption, respectively. The rate constant measured at 298 K is found to be somewhat faster than previously accepted values, with a negative temperature dependence. Calculations of a one-dimensional transport-kinetic atmospheric model on the basis of the new rate constant indicate reductions in O3 depletion due to chlorofluoromethane release and NOx injection, of magnitudes dependent on the nature of the reaction products.

Far-infrared Spectroscopic Characterization of Anti-vinyl Alcohol

NASA Astrophysics Data System (ADS)

Bunn, Hayley; Soliday, Rebekah M.; Sumner, Isaiah; Raston, Paul L.

2017-09-01

We report a detailed analysis of the high-resolution far-infrared spectrum of anti-vinyl alcohol, which has been previously identified toward Sagittarius B2(N). The ν 15 OH torsional fundamental investigated here is more than 200 cm-1 removed from the next nearest vibration, making it practically unperturbed and ideal to help refine the ground state rotational constants that were previously determined from 25 microwave lines. We assigned 1335 lines within the ν 15 fundamental centered at 261.5512 cm-1, with J and K a ranges of 1-59 and 0-16, respectively. The microwave and far-infrared line positions were fit with Watson-type A- and S-reduced Hamiltonians, with the inclusion of quartic and select sextic distortion terms. This resulted in a significant refinement of the ground state constants, in addition to the determination of the {ν }15=1 state constants for the first time. The spectroscopic parameters are in good agreement with the results from anharmonic coupled-cluster calculations, and should be useful in searches for rotationally and/or vibrationally warm anti-vinyl alcohol in interstellar molecular clouds.

Evaluation of constant-Weber-number scaling for icing tests

NASA Technical Reports Server (NTRS)

Anderson, David N.

1996-01-01

Previous studies showed that for conditions simulating an aircraft encountering super-cooled water droplets the droplets may splash before freezing. Other surface effects dependent on the water surface tension may also influence the ice accretion process. Consequently, the Weber number appears to be important in accurately scaling ice accretion. A scaling method which uses a constant-Weber-number approach has been described previously; this study provides an evaluation of this scaling method. Tests are reported on cylinders of 2.5 to 15-cm diameter and NACA 0012 airfoils with chords of 18 to 53 cm in the NASA Lewis Icing Research Tunnel (IRT). The larger models were used to establish reference ice shapes, the scaling method was applied to determine appropriate scaled test conditions using the smaller models, and the ice shapes were compared. Icing conditions included warm glaze, horn glaze and mixed. The smallest size scaling attempted was 1/3, and scale and reference ice shapes for both cylinders and airfoils indicated that the constant-Weber-number scaling method was effective for the conditions tested.

Determination of the Boltzmann constant with cylindrical acoustic gas thermometry: new and previous results combined

NASA Astrophysics Data System (ADS)

Feng, X. J.; Zhang, J. T.; Lin, H.; Gillis, K. A.; Mehl, J. B.; Moldover, M. R.; Zhang, K.; Duan, Y. N.

2017-10-01

We report a new determination of the Boltzmann constant k B using a cylindrical acoustic gas thermometer. We determined the length of the copper cavity from measurements of its microwave resonance frequencies. This contrasts with our previous work (Zhang et al 2011 Int. J. Thermophys. 32 1297, Lin et al 2013 Metrologia 50 417, Feng et al 2015 Metrologia 52 S343) that determined the length of a different cavity using two-color optical interferometry. In this new study, the half-widths of the acoustic resonances are closer to their theoretical values than in our previous work. Despite significant changes in resonator design and the way in which the cylinder length is determined, the value of k B is substantially unchanged. We combined this result with our four previous results to calculate a global weighted mean of our k B determinations. The calculation follows CODATA’s method (Mohr and Taylor 2000 Rev. Mod. Phys. 72 351) for obtaining the weighted mean value of k B that accounts for the correlations among the measured quantities in this work and in our four previous determinations of k B. The weighted mean {{\\boldsymbol{\\hat{k}}}{B}} is 1.380 6484(28)  ×  10-23 J K-1 with the relative standard uncertainty of 2.0  ×  10-6. The corresponding value of the universal gas constant is 8.314 459(17) J K-1 mol-1 with the relative standard uncertainty of 2.0  ×  10-6.

Low-energy vibrations of the group 10 metal monocarbonyl MCO (M = Ni, Pd, and Pt): rotational spectroscopy and force field analysis.

PubMed

Okabayashi, Toshiaki; Yamamoto, Takuya; Okabayashi, Emi Y; Tanimoto, Mitsutoshi

2011-03-17

The rotational spectra of NiCO and PdCO in the ground and ν(2) excited vibrational states were observed by employing a source-modulated microwave spectrometer. The NiCO and PdCO molecules were generated in a free space cell by the sputtering reaction of nickel and palladium sheets, respectively, lining the inner surface of a stainless steel cathode with a dc glow plasma of CO and Ar. The molecular constants of NiCO and PdCO were determined by least-squares analysis. By force field analysis for the molecular constants of not only NiCO and PdCO but also of PtCO as previously reported, the harmonic force constants were determined for these three group 10 metal monocarbonyls. The vibrational wavenumbers derived for the lower M-C stretching vibrations were in good agreement with those obtained from the IR spectra in noble gas matrices and those predicted by several quantum chemical calculations published in the past. The bending vibrational wavenumbers derived by the force field analysis were also consistent with most quantum chemical calculations previously reported, but showed systematic discrepancies from the matrix IR values by about 40 cm(-1), even after reassignment (ν(2) band → 2ν(2) band) of the matrix IR spectra of PdCO and PtCO.

Comments on "Theoretical investigation on H abstraction reaction mechanisms and rate constants of sevoflurane with the OH radical" [Chem. Phys. Lett. 692 (2018) 345-352

NASA Astrophysics Data System (ADS)

Mai, Tam V.-T.; Duong, Minh v.; Huynh, Lam K.

2018-03-01

This short communication discusses the role of the newly-found lowest-lying structures of the transition states (∼3.0 kcal/mol lower than those previously reported by Ren et al. (2018), together with the inclusion of the hindered internal rotation correction, in obtaining reliable kinetic data for the hydrogen abstraction from sevoflurane by OH radical. With the new structures and the more rigorous kinetic model, the calculated rate constants agree much better with the experimental data than those suggested by Ren and coworkers.

Discovery of a Significant Acetone•Hydroperoxy Adduct Chaperone Effect and Its Impact on the Determination of Room Temperature Rate Constants for Acetonylperoxy/Hydroperoxy Self-Reactions and Cross Reaction Via Infrared Kinetic Spectroscopy.

NASA Astrophysics Data System (ADS)

Grieman, F. J.; Hui, A. O.; Okumura, M.; Sander, S. P.

2017-12-01

In order to model the upper troposphere/lower stratosphere in regions containing acetone properly, the kinetics of the acetonylperoxy/hydroperoxy self-reactions and cross reaction have been studied over a wide temperature range using Infrared Kinetic Spectroscopy. We report here the determination of different rate constants for the acetonylperoxy chemistry that we obtained at 298 K compared to currently accepted values. A considerable increase in the observed HO2 self-reaction rate constant due to rate enhancement via the chaperone effect from the reaction between HO2 and the (CH3)2CO•HO2 hydrogen-bonded adduct, even at room temperature, was discovered that was previously ignored. Correct determination of the acetonylperoxy and hydroperoxy kinetics must include this dependence of the HO2 self-reaction rate on acetone concentration. Via excimer laser flash photolysis to create the radical reactants, HO2 absorption was monitored in the infrared by diode laser wavelength modulation detection simultaneously with CH3C(O)CH2O2absorption monitored in the ultraviolet at 300 nm as a function of time. Resulting decay curves were fit concurrently first over a short time scale to obtain the rate constants minimizing subsequent product reactions. Modeling/fitting with a complete reaction scheme was then performed to refine the rate constants and test their veracity. Experiments were carried out over a variety of concentrations of acetone and methanol. Although no effect due to methanol concentration was found at room temperature, the rate constant for the hydroperoxy self-reaction was found to increase linearly with acetone concentration which is interpreted as the adduct being formed and resulting in a chaperone mechanism that enhances the self-reaction rate: (CH3)2CO·HO2 + HO2 → H2O2 + O2 + (CH3)2CO Including this effect, the resulting room temperature rate constants for the cross reaction and the acetonylperoxy self-reaction were found to be 2-3 times smaller than previously reported. This complex formation/chaperone mechanism is similar to that found for methanol, but different in that it occurs at room temperature. No precursor concentration dependence was found for the acetonylperoxy radical reactions. The equilibrium constant for the complex formation will also be presented.

Complexation of lanthanides and actinides by acetohydroxamic acid

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

Taylor, R.J.; Sinkov, S.I.; Choppin, G.R.

2008-07-01

Acetohydroxamic acid (AHA) has been proposed as a suitable reagent for the complexant-based, as opposed to reductive, stripping of plutonium and neptunium ions from the tributylphosphate solvent phase in advanced PUREX or UREX processes designed for future nuclear-fuel reprocessing. Stripping is achieved by the formation of strong hydrophilic complexes with the tetravalent actinides in nitric acid solutions. To underpin such applications, knowledge of the complexation constants of AHA with all relevant actinide (5f) and lanthanide (4f) ions is therefore important. This paper reports the determination of stability constants of AHA with the heavier lanthanide ions (Dy-Yb) and also U(IV) andmore » Th(IV) ions. Comparisons with our previously published AHA stability-constant data for 4f and 5f ions are made. (authors)« less

Free energy perturbation method for measuring elastic constants of liquid crystals

NASA Astrophysics Data System (ADS)

Joshi, Abhijeet

There is considerable interest in designing liquid crystals capable of yielding specific morphological responses in confined environments, including capillaries and droplets. The morphology of a liquid crystal is largely dictated by the elastic constants, which are difficult to measure and are only available for a handful of substances. In this work, a first-principles based method is proposed to calculate the Frank elastic constants of nematic liquid crystals directly from atomistic models. These include the standard splay, twist and bend deformations, and the often-ignored but important saddle-splay constant. The proposed method is validated using a well-studied Gay-Berne(3,5,2,1) model; we examine the effects of temperature and system size on the elastic constants in the nematic and smectic phases. We find that our measurements of splay, twist, and bend elastic constants are consistent with previous estimates for the nematic phase. We further outline the implementation of our approach for the saddle-splay elastic constant, and find it to have a value at the limits of the Ericksen inequalities. We then proceed to report results for the elastic constants commonly known liquid crystals namely 4-pentyl-4'-cynobiphenyl (5CB) using atomistic model, and show that the values predicted by our approach are consistent with a subset of the available but limited experimental literature.

Children’s Dietary Recalls from Three Validation Studies: Types of Intrusion Vary with Retention Interval

PubMed Central

Baxter, Suzanne Domel; Hardin, James W.; Smith, Albert F.; Royer, Julie A.; Guinn, Caroline H.

2008-01-01

SUMMARY Using previously collected data of fourth-grade children observed eating school meals and then interviewed, we categorized intrusions (food items reported but not observed eaten) as stretches (on the child’s tray) or confabulations (not on the child’s tray). We investigated intrusions, confabulations, and stretches, and the role of liking, at different retention intervals (morning interviews about the previous day’s intake; evening interviews about that day’s intake) and under different reporting-order prompts (forward; reverse). As retention interval between consumption and report increased, the likelihood 1) increased that reported items were intrusions, that reported items were confabulations, and that intrusions were confabulations; and 2) was constant that reported items were stretches. Results concerning reporting-order prompts were inconclusive. Liking ratings were higher for matches (reports of items observed eaten) than stretches, for confabulations than stretches, and for matches than omissions (unreported items observed eaten), but did not vary by retention interval or reporting-order prompts. PMID:19023454

Long-Term Efficacy of Constant Current Deep Brain Stimulation in Essential Tremor.

PubMed

Rezaei Haddad, Ali; Samuel, Michael; Hulse, Natasha; Lin, Hsin-Ying; Ashkan, Keyoumars

2017-07-01

Ventralis intermedius deep brain stimulation is an established intervention for medication-refractory essential tremor. Newer constant current stimulation technology offers theoretical advantage over the traditional constant voltage systems in terms of delivering a more biologically stable therapy. There are no previous reports on the outcomes of constant current deep brain stimulation in the treatment of essential tremor. This study aimed to evaluate the long-term efficacy of ventralis intermedius constant current deep brain stimulation in patients diagnosed with essential tremor. Essential tremor patients implanted with constant current deep brain stimulation for a minimum of three years were evaluated. Clinical outcomes were assessed using the Fahn-Tolosa-Marin tremor rating scale at baseline and postoperatively at the time of evaluation. The quality of life in the patients was assessed using the Quality of Life in Essential Tremor questionnaire. Ten patients were evaluated with a median age at evaluation of 74 years (range 66-79) and a mean follow up time of 49.7 (range 36-78) months since starting stimulation. Constant current ventralis intermedius deep brain stimulation was well tolerated and effective in all patients with a mean score improvement from 50.7 ± 5.9 to 17.4 ± 5.7 (p = 0.0020) in the total Fahn-Tolosa-Marin rating scale score (65.6%). Furthermore, the total combined mean Quality of Life in Essential Tremor score was improved from 56.2 ± 4.9 to 16.8 ± 3.5 (p value = 0.0059) (70.1%). This report shows that long-term constant current ventralis intermedius deep brain stimulation is a safe and effective intervention for essential tremor patients. © 2017 International Neuromodulation Society.

Kinetic study of the oxidation of 4-hydroxyanisole catalyzed by tyrosinase.

PubMed

Espín, J C; Varón, R; Tudela, J; García-Cánovas, F

1997-05-01

Despite the importance of the substrate 4-hydroxyanisole in melanoma therapy, the kinetics of its oxidation catalyzed by tyrosinase has never been properly characterized. This approach is reported here for the first time. The applicability to 4-hydroxyanisole of the reaction mechanism of tyrosinase previously proposed for other monophenols has been corroborated. The Michaelis constant for the oxidation of 4-hydroxyanisole catalyzed by mushroom tyrosinase was (62 +/- 1.5) microM at pH 7 and increased when the pH decreased, reaching a value of (195 +/- 5) microM at pH 5.5. However the maximum steady-state rate, whose value was (0.54 +/- 0.01) microM/min, did not change with the pH. The apparent catalytic constant was (184 +/- 5) s-1, around twenty three times higher than that previously described for L-tyrosine (8 s-1).

Helping the Helper: Analyzing the Effects of Clinical Supervision on Levels of Burnout

ERIC Educational Resources Information Center

White, Adrienne Denise

2017-01-01

The hallmark of mental health counseling requires working with people who are experiencing current or previous pain, trauma, stress, grief, anxiety, as well as various complicated psychological needs (Maslach et al, 1996). The constant experience of sadness and emotional fatigue can lead to a form of stress called burnout. Studies report that…

Revised Model of Calcium and Magnesium Binding to the Bacterial Cell Wall

PubMed Central

Thomas, Kieth J.; Rice, Charles V.

2014-01-01

Metals bind to the bacterial cell wall yet the binding mechanisms and affinity constants are not fully understood. The cell wall of gram positive bacteria is characterized by a thick layer of peptidoglycan and anionic teichoic acids anchored in the cytoplasmic membrane (lipoteichoic acid) or covalently bound to the cell wall (wall teichoic acid). The polyphosphate groups of teichoic acid provide one-half of the metal binding sites for calcium and magnesium, contradicting previous reports that calcium binding is 100% dependent on teichoic acid. The remaining binding sites are formed with the carboxyl units of peptidoglycan. In this work we report equilibrium association constants and total metal binding capacities for the interaction of calcium and magnesium ions with the bacterial cell wall. Metal binding is much stronger and previously reported. Curvature of Scatchard plots from the binding data and the resulting two regions of binding affinity suggest the presence of negative cooperative binding, meaning that the binding affinity decreases as more ions become bound to the sample. For Ca2+, Region I has a KA = (1.0 ± 0.2) × 106 M−1 and Region II has a KA = (0.075 ± 0.058) × 106 M−1. For Mg2+, KA1 = (1.5 ± 0.1) × 106 and KA2 = (0.17 ± 0.10) × 106. A binding capacity (η) is reported for both regions. However, since binding is still occurring in Region II, the total binding capacity is denoted by η2, which are 0.70 ± 0.04 µmol/mg and 0.67 ± 0.03 µmol/mg for Ca2+ and Mg2+ respectively. These data contradict the current paradigm of there being a single metal affinity value that is constant over a range of concentrations. We also find that measurement of equilibrium binding constants is highly sample dependent, suggesting a role for diffusion of metals through heterogeneous cell wall fragments. As a result, we are able to reconcile many contradictory theories that describe binding affinity and the binding mode of divalent metal cations. PMID:25315444

The structural and optical constants of Ag2S semiconductor nanostructure in the Far-Infrared.

PubMed

Zamiri, Reza; Abbastabar Ahangar, Hossein; Zakaria, Azmi; Zamiri, Golnoosh; Shabani, Mehdi; Singh, Budhendra; Ferreira, J M F

2015-01-01

In this paper a template-free precipitation method was used as an easy and low cost way to synthesize Ag2S semiconductor nanoparticles. The Kramers-Kronig method (K-K) and classical dispersion theory was applied to calculate the optical constants of the prepared samples, such as the reflective index n(ω) and dielectric constant ε(ω) in Far-infrared regime. Nanocrystalline Ag2S was synthesized by a wet chemical precipitation method. Ag2S nanoparticle was characterized by X-ray diffraction, Scanning Electron Microscopy, UV-visible, and FT-IR spectrometry. The refinement of the monoclinic β-Ag2S phase yielded a structure solution similar to the structure reported by Sadanaga and Sueno. The band gap of Ag2S nanoparticles is around 0.96 eV, which is in good agreement with previous reports for the band gap energy of Ag2S nanoparticles (0.9-1.1 eV). The crystallite size of the synthesized particles was obtained by Hall-Williamson plot for the synthesized Ag2S nanoparticles and it was found to be 217 nm. The Far-infrared optical constants of the prepared Ag2S semiconductor nanoparticles were evaluated by means of FTIR transmittance spectra data and K-K method. Graphical abstractThe Far-infrared optical constants of Ag2S semiconductor nanoparticles.

Room-temperature and temperature-dependent QSRR modelling for predicting the nitrate radical reaction rate constants of organic chemicals using ensemble learning methods.

PubMed

Gupta, S; Basant, N; Mohan, D; Singh, K P

2016-07-01

Experimental determinations of the rate constants of the reaction of NO3 with a large number of organic chemicals are tedious, and time and resource intensive; and the development of computational methods has widely been advocated. In this study, we have developed room-temperature (298 K) and temperature-dependent quantitative structure-reactivity relationship (QSRR) models based on the ensemble learning approaches (decision tree forest (DTF) and decision treeboost (DTB)) for predicting the rate constant of the reaction of NO3 radicals with diverse organic chemicals, under OECD guidelines. Predictive powers of the developed models were established in terms of statistical coefficients. In the test phase, the QSRR models yielded a correlation (r(2)) of >0.94 between experimental and predicted rate constants. The applicability domains of the constructed models were determined. An attempt has been made to provide the mechanistic interpretation of the selected features for QSRR development. The proposed QSRR models outperformed the previous reports, and the temperature-dependent models offered a much wider applicability domain. This is the first report presenting a temperature-dependent QSRR model for predicting the nitrate radical reaction rate constant at different temperatures. The proposed models can be useful tools in predicting the reactivities of chemicals towards NO3 radicals in the atmosphere, hence, their persistence and exposure risk assessment.

Analysis of water microdroplet condensation on silicon surfaces

NASA Astrophysics Data System (ADS)

Honda, Takuya; Fujimoto, Kenya; Yoshimoto, Yuta; Mogi, Katsuo; Kinefuchi, Ikuya; Sugii, Yasuhiko; Takagi, Shu; Univ. of Tokyo Team; Tokyo Inst. of Tech. Team

2016-11-01

We observed the condensation process of water microdroplets on flat silicon (100) surfaces by means of the sequential visualization of the droplets using an environmental scanning electron microscope. As previously reported for nanostructured surfaces, the condensation process of water microdroplets on the flat silicon surfaces also exhibits two modes: the constant base (CB) area mode and the constant contact angle (CCA) mode. In the CB mode, the contact angle increases with time while the base diameter is constant. Subsequently, in the CCA mode, the base diameter increases with time while the contact angle remains constant. The dropwise condensation model regulated by subcooling temperature does not reproduce the experimental results. Because the subcooling temperature is not constant in the case of a slow condensation rate, this model is not applicable to the condensation of the long time scale ( several tens of minutes). The contact angle of water microdroplets ( several μm) tended to be smaller than the macro contact angle. Two hypotheses are proposed as the cause of small contact angles: electrowetting and the coalescence of sub- μm water droplets.

Discrete Element Modeling (DEM) of Triboelectrically Charged Particles: Revised Experiments

NASA Technical Reports Server (NTRS)

Hogue, Michael D.; Calle, Carlos I.; Curry, D. R.; Weitzman, P. S.

2008-01-01

In a previous work, the addition of basic screened Coulombic electrostatic forces to an existing commercial discrete element modeling (DEM) software was reported. Triboelectric experiments were performed to charge glass spheres rolling on inclined planes of various materials. Charge generation constants and the Q/m ratios for the test materials were calculated from the experimental data and compared to the simulation output of the DEM software. In this paper, we will discuss new values of the charge generation constants calculated from improved experimental procedures and data. Also, planned work to include dielectrophoretic, Van der Waals forces, and advanced mechanical forces into the software will be discussed.

Chronic 'speech catatonia' with constant logorrhea, verbigeration and echolalia successfully treated with lorazepam: a case report.

PubMed

Lee, Joseph W Y

2004-12-01

Logorrhea, verbigeration and echolalia persisted unremittingly for 3 years, with occasional short periods of motoric excitement, in a patient with mild intellectual handicap suffering from chronic schizophrenia. The speech catatonic symptoms, previously refractory to various antipsychotics, responded promptly to lorazepam, a benzodiazepine with documented efficacy in the treatment of acute catatonia but not chronic catatonia. It is suggested that pathways in speech production were selectively involved in the genesis of the chronic speech catatonic syndrome, possibly a rare form of chronic catatonia not previously described.

The stability of gadolinium-based contrast agents in human serum: A reanalysis of literature data and association with clinical outcomes.

PubMed

Prybylski, John P; Semelka, Richard C; Jay, Michael

2017-05-01

To reanalyze literature data of gadolinium (Gd)-based contrast agents (GBCAs) in plasma with a kinetic model of dissociation to provide a comprehensive assessment of equilibrium conditions for linear GBCAs. Data for the release of Gd from GBCAs in human serum was extracted from a previous report in the literature and fit to a kinetic dissociation/association model. The conditional stabilities (logK cond ) and percent intact over time were calculated using the model rate constants. The correlations between clinical outcomes and logK cond or other stability indices were determined. The release curves for Omniscan®, gadodiamide, OptiMARK®, gadoversetamide Magnevist® and Multihance® were extracted and all fit well to the kinetic model. The logK cond s calculated from the rate constants were on the order of ~4-6, and were not significantly altered by excess ligand or phosphate. The stability constant based on the amount intact by the initial elimination half-life of GBCAs in plasma provided good correlation with outcomes observed in patients. Estimation of the kinetic constants for GBCA dissociation/association revealed that their stability in physiological fluid is much lower than previous approaches would suggest, which correlates well with deposition and pharmacokinetic observations of GBCAs in human patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Review of lattice results concerning low-energy particle physics: Flavour Lattice Averaging Group (FLAG).

PubMed

Aoki, S; Aoki, Y; Bečirević, D; Bernard, C; Blum, T; Colangelo, G; Della Morte, M; Dimopoulos, P; Dürr, S; Fukaya, H; Golterman, M; Gottlieb, Steven; Hashimoto, S; Heller, U M; Horsley, R; Jüttner, A; Kaneko, T; Lellouch, L; Leutwyler, H; Lin, C-J D; Lubicz, V; Lunghi, E; Mawhinney, R; Onogi, T; Pena, C; Sachrajda, C T; Sharpe, S R; Simula, S; Sommer, R; Vladikas, A; Wenger, U; Wittig, H

2017-01-01

We review lattice results related to pion, kaon, D - and B -meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the determination of the light-quark masses, the form factor [Formula: see text], arising in the semileptonic [Formula: see text] transition at zero momentum transfer, as well as the decay constant ratio [Formula: see text] and its consequences for the CKM matrix elements [Formula: see text] and [Formula: see text]. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of [Formula: see text] and [Formula: see text] Chiral Perturbation Theory. We review the determination of the [Formula: see text] parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for [Formula: see text] and [Formula: see text] (also new compared to the previous review), as well as those for D - and B -meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant [Formula: see text].

Experimental and Estimated Rate Constants for the Reactions of Hydroxyl Radicals with Several Halocarbons

NASA Technical Reports Server (NTRS)

DeMore, W.B.

1996-01-01

Relative rate experiments are used to measure rate constants and temperature dependencies of the reactions of OH with CH3F (41), CH2FCl (31), CH2BrCl (30B1), CH2Br2 (3OB2), CHBr3 (2OB3), CF2BrCHFCl (123aBl(alpha)), and CF2ClCHCl2 (122). Rate constants for additional compounds of these types are estimated using an empirical rate constant estimation method which is based on measured rate constants for a wide range of halocarbons. The experimental data are combined with the estimated and previously reported rate constants to illustrate the effects of F, Cl, and Br substitution on OH rate constants for a series of 19 halomethanes and 25 haloethanes. Application of the estimation technique is further illustrated for some higher hydrofluorocarbons (HFCs), including CHF2CF2CF2CF2H (338pcc), CF3CHFCHFCF2CF3 (43-10mee), CF3CH2CH2CF3 (356ffa), CF3CH2CF2CH2CF3 (458mfcf), CF3CH2CHF2 (245fa), and CF3CH2CF2CH3 (365mfc). The predictions are compared with literature data for these compounds.

Rate constants and temperature dependences for the reactions of hydroxyl radical with several halogenated methanes, ethanes, and propanes by relative rate measurements

NASA Technical Reports Server (NTRS)

Hsu, K.-J.; DeMore, W. B.

1995-01-01

Rate constants of 15 OH reactions with halogen-substituted alkanes, C1 to C3, were studied using a relative rate technique in the temperature range 283-403 K. Compounds studied were CHF2Cl (22), CHF2Br (22B), CH3F (41), CH2F2 (32), CHF3 (23), CHClFCCl2F (122a), CHCl2CF3 (123), CHClFCF3 (124), CH3CF3 (143a), CH3CH2F (161), CF3CHFCF3 (227ea), CF3CH2CF3 (236fa), CF3CHFCHF2 (236ea), and CHF2CF2CH2F (245ca). Using CH4, CH3CCl3, CF3CF2H, and C2H6 as primary reference standards (JPL 92-20 rate constants), absolute rate constants are derived. Results are in good agreement with previous experimental results for six of the compounds studied, including CHF2Cl, CHF2Br, CH2F2, CH3CF3, CHFClCFCl2, and CF3CHFCF3. For the remainder the relative rate constants are lower than those derived from experiments in which OH loss was used to measure the reaction rate. Comparisons of the derived Arrhenius A factors with previous literature transition-state calculations show order of magnitude agreement in most cases. However, the experimental A factors show a much closer proportionality to the number of H atoms in the molecule than is evident from the transition state calculations. For most of the compounds studied, an A factor of (8 +/- 3)E-13 cm(exp 3)/(molecule s) per C-H bond is observed. A new measurement of the ratio k(CH3CCl3)/k(CH4) is reported that is in good agreement with previous data.

Three-body interactions and the elastic constants of hcp solid 4He

NASA Astrophysics Data System (ADS)

Barnes, Ashleigh L.; Hinde, Robert J.

2017-09-01

The effect of three-body interactions on the elastic properties of hexagonal close packed solid 4He is investigated using variational path integral (VPI) Monte Carlo simulations. The solid's nonzero elastic constants are calculated, at T = 0 K and for a range of molar volumes from 7.88 cm3/mol to 20.78 cm3/mol, from the bulk modulus and the three pure shear constants C0, C66, and C44. Three-body interactions are accounted for using our recently reported perturbative treatment based on the nonadditive three-body potential of Cencek et al. Previous studies have attempted to account for the effect of three-body interactions on the elastic properties of solid 4He; however, these calculations have treated zero point motions using either the Einstein or Debye approximations, which are insufficient in the molar volume range where solid 4He is characterized as a quantum solid. Our VPI calculations allow for a more accurate treatment of the zero point motions which include atomic correlation. From these calculations, we find that agreement with the experimental bulk modulus is significantly improved when three-body interactions are considered. In addition, three-body interactions result in non-negligible differences in the calculated pure shear constants and nonzero elastic constants, particularly at higher densities, where differences of up to 26.5% are observed when three-body interactions are included. We compare to the available experimental data and find that our results are generally in as good or better agreement with experiment as previous theoretical investigations.

Increased Mortality in a Colony of Zebra Finches Exposed to Continuous Light

PubMed Central

Snyder, Jessica M; Molk, Denise M; Treuting, Piper M

2013-01-01

Over a 1-mo period, increased morbidity and mortality occurred in a flock of zebra finches (Taeniopygia guttata). Complete postmortem examination was performed on 6 of the affected birds, 4 of which subsequently were diagnosed with the avian gastric yeast previously known as megabacteriosis (Macrorhabdus ornithogaster). The remaining 2 birds were diagnosed with a cloacal abscess and with large bowel perforation and peritonitis. All the birds had been prophylactically treated with amphotericin B for megabacteria 2 mo previously. An environmental assessment revealed that the light cycle had been altered, and the birds were being exposed to constant light. With correction of the light cycle, the health of the birds improved dramatically. The remaining birds were treated again with amphotericin B, and baseline mortality returned to normal. The birds in this report show several similarities to previous reports of sleep deprivation syndrome in mammals. PMID:23849414

Initial SAM Calibration Gas Experiments on Mars: Quadrupole Mass Spectrometer Results and Implications

NASA Technical Reports Server (NTRS)

Franz, Heather B.; Trainer, Melissa G.; Malespin, Charles A.; Mahaffy, Paul R.; Atreya, Sushil K.; Becker, Richard H,; Benna, Mehdi; Conrad, Pamela G.; Eigenbrode, Jennifer L.; Freissinet, Caroline;

Initial SAM calibration gas experiments on Mars: Quadrupole mass spectrometer results and implications

NASA Astrophysics Data System (ADS)

Franz, Heather B.; Trainer, Melissa G.; Malespin, Charles A.; Mahaffy, Paul R.; Atreya, Sushil K.; Becker, Richard H.; Benna, Mehdi; Conrad, Pamela G.; Eigenbrode, Jennifer L.; Freissinet, Caroline; Manning, Heidi L. K.; Prats, Benito D.; Raaen, Eric; Wong, Michael H.

2017-04-01

The Sample Analysis at Mars (SAM) instrument suite of the Mars Science Laboratory (MSL) Curiosity rover is equipped to analyze both martian atmospheric gases and volatiles released by pyrolysis of solid surface materials, with target measurements including chemical and isotopic composition (Mahaffy et al., 2012). To facilitate assessment of instrument performance and validation of results obtained on Mars, SAM houses a calibration cell containing CO2, Ar, N2, Xe, and several fluorinated hydrocarbon compounds (Franz et al., 2014; Mahaffy et al., 2012). This report describes the first two experiments utilizing this calibration cell on Mars and gives results from analysis of data acquired with the SAM Quadrupole Mass Spectrometer (QMS). These data support the accuracy of isotope ratios obtained with the QMS (Conrad et al., 2016; Mahaffy et al., 2013) and provide ground-truth for reassessment of analytical constants required for atmospheric measurements, which were reported in previous contributions (Franz et al., 2015, 2014). The most significant implication of the QMS data involves reinterpretation of pre-launch contamination previously believed to affect only CO abundance measurements (Franz et al., 2015) to affect N2 abundances, as well. The corresponding adjustment to the N2 calibration constant presented here brings the atmospheric volume mixing ratios for Ar and N2 retrieved by SAM into closer agreement with those reported by the Viking mission (Owen et al., 1977; Oyama and Berdahl, 1977).

FAST TRACK COMMUNICATION: Evaluation of the In concentration of an InxGa1-xSb alloy layer in cross-sectional HRTEM images of III-V semiconductor superlattices

NASA Astrophysics Data System (ADS)

Quan, Maohua; Guo, Fengyun; Li, Meicheng; Zhao, Liancheng

2010-08-01

Atomic-scale positional resolved lattice spacing measurement is used to study the In concentration of the alloy layer in InAs/InxGa1-xSb superlattices by the molecular beam epitaxy techniques. The unstrained lattice distance d along three directions, [0 0 1], [1 1 0] and [1 1 1], was measured and the average lattice constant was calculated. The experimental lattice constants of InAs layers are almost equal to the theoretical ones. We have found that the average lattice constant of In0.25Ga0.75Sb alloy layers is in good agreement with previously reported Vegard's values, being slightly larger. The results indicate that the In concentration of x = 0.18 has a larger deviation compared with the designed values.

Constant angular velocity of the wrist during the lifting of a sphere.

PubMed

Chappell, P H; Metcalf, C D; Burridge, J H; Yule, V T; Pickering, R M

2010-05-01

The primary objective of the experiments was to investigate the wrist motion of a person while they were carrying out a prehensile task from a clinical hand function test. A six-camera movement system was used to observe the wrist motion of 10 participants. A very light sphere and a heavy sphere were used in the experiments to study any mass effects. While seated at a table, a participant moved a sphere over a small obstacle using their dominant hand. The participants were observed to move their wrist at a constant angular velocity. This phenomenon has not been reported previously. Theoretically, the muscles of the wrist provide an impulse of force at the start of the rotation while the forearm maintains a constant vertical force on a sphere. Light-heavy mean differences for the velocities, absolute velocities, angles and times taken showed no significant differences (p = 0.05).

Details of the 1998 Watt Balance Experiment Determining the Planck Constant

PubMed Central

Steiner, Richard; Newell, David; Williams, Edwin

2005-01-01

The National Institute of Standards and Technology (NIST) watt balance experiment completed a determination of Planck constant in 1998 with a relative standard uncertainty of 87 × 10−9 (k = 1), concurrently with an upper limit on the drift rate of the SI kilogram mass standard. A number of other fundamental physical constants with uncertainties dominated by this result are also calculated. This paper focuses on the details of the balance apparatus, the measurement and control procedures, and the reference calibrations. The alignment procedures are also described, as is a novel mutual inductance measurement procedure. The analysis summary discusses the data noise sources and estimates for the Type B uncertainty contributions to the uncertainty budget. Much of this detail, some historical progression, and a few recent findings have not been included in previous papers reporting the results of this experiment. PMID:27308100

Decreased shoulder function and pain common in recreational badminton players.

PubMed

Fahlström, M; Söderman, K

2007-06-01

The aim of this study was to describe the prevalence and consequences of painful conditions in the shoulder region in recreational badminton players. A questionnaire study was performed on 99 players, of whom 57 were also assessed with Constant score. Previous or present pain in the dominant shoulder was reported by 52% of the players. Sixteen percent of the players had on-going shoulder pain associated with badminton play. A majority of these players reported that their training habits were affected by the pain. Total Constant score was lower in the painful shoulders. Furthermore, range of active pain-free shoulder abduction was decreased. However, isometric shoulder strength test showed no differences when compared with pain-free shoulders. Even though the pain caused functional problems, the players were still playing with on-going symptoms. The diagnoses were mostly unknown, although history and clinical tests indicate problems resembling subacromial impingement.

A Thermodynamic Description of the Adsorption of Simple Water-Soluble Peptoids to Silica.

PubMed

Calkins, Anna L; Yin, Jennifer; Rangel, Jacenda L; Landry, Madeleine R; Fuller, Amelia A; Stokes, Grace Y

2016-11-08

The first report of a water-soluble peptoid adsorbed to silica monitored by second harmonic generation (SHG) at the liquid/solid interface is presented here. The molecular insights gained from these studies will inform the design and preparation of novel peptoid coatings. Simple 6- and 15-residue peptoids were dissolved in phosphate buffered saline and adsorbed to bare silica surfaces. Equilibrium binding constants and relative surface concentrations of adsorbed peptoids were determined from fits to the Langmuir model. Complementary fluorescence spectroscopy studies were used to quantify the maximum surface excess. Binding constants, determined here by SHG, were comparable to those previously reported for cationic proteins and small molecules. Enthalpies and free energies of adsorption were determined to elucidate thermodynamic driving forces. Circular dichroism spectra confirm that minimal conformational changes occur when peptoids are adsorbed to silica while pH studies indicate that electrostatic interactions impact adsorption.

Inorganic Halogen Oxidizer Research.

DTIC Science & Technology

1980-03-17

Synthesis, Novel Oxidizers, Solid-Propellant NF3 /F2 Gas Generators, Perfluoro- a- ammonium Salts, Perchlorates, Pentafluorooxouranate, Fluorosulfate...kcal mol I previously reported.’ by immersion into i constant-temperature 140.05 () circulating oil The fact that the small mole fraction ranges of...reactor higher tenperatures over almost t he entire nnole fraction () into the hot oil bath. the reactor was evacnaied. and the pressure range A mxpical

Henry's law constants of polyols

NASA Astrophysics Data System (ADS)

Compernolle, S.; Müller, J.-F.

2014-12-01

Henry's law constants (HLC) are derived for several polyols bearing between 2 and 6 hydroxyl groups, based on literature data for water activity, vapour pressure and/or solubility. While deriving HLC and depending on the case, also infinite dilution activity coefficients (IDACs), solid state vapour pressures or activity coefficient ratios are obtained as intermediate results. An error analysis on the intermediate quantities and the obtained HLC is included. For most compounds, these are the first values reported, while others compare favourably with literature data in most cases. Using these values and those from a previous work (Compernolle and Müller, 2014), an assessment is made on the partitioning of polyols, diacids and hydroxy acids to droplet and aqueous aerosol.

Milestone report on MD potential development for uranium silicide

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

Yu, Jianguo; Zhang, Yongfeng; Hales, Jason Dean

2016-03-01

This report summarizes the progress on the interatomic potential development of triuranium-disilicide (U 3Si 2) for molecular dynamics (MD) simulations. The development is based on the Tersoff type potentials for single element U and Si. The Si potential is taken from the literature and a Tersoff type U potential is developed in this project. With the primary focus on the U 3Si 2 phase, some other U-Si systems such as U 3Si are also included as a test of the transferability of the potentials for binary U-Si phases. Based on the potentials for unary U and Si, two sets ofmore » parameters for the binary U-Si system are developed using the Tersoff mixing rules and the cross-term fitting, respectively. The cross-term potential is found to give better results on the enthalpy of formation, lattice constants and elastic constants than those produced by the Tersoff mixing potential, with the reference data taken from either experiments or density functional theory (DFT) calculations. In particular, the results on the formation enthalpy and lattice constants for the U 3Si 2 phase and lattice constants for the high temperature U 3Si (h-U 3Si) phase generated by the cross-term potential agree well with experimental data. Reasonable agreements are also reached on the elastic constants of U 3Si 2, on the formation enthalpy for the low temperature U 3Si (m-U 3Si) and h-U 3Si phases, and on the lattice constants of m-U 3Si phase. All these phases are predicted to be mechanically stable. The unary U potential is tested for three metallic U phases (α, β, γ). The potential is found capable to predict the cohesive energies well against experimental data for all three phases. It matches reasonably with previous experiments on the lattice constants and elastic constants of αU.« less

Physicochemical properties of polycyclic aromatic hydrocarbons: Aqueous solubilities, n-octanol/water partition coefficients, and Henry`s law constants

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

Maagd, P.G.J. de; Opperhuizen, A.; Sijm, D.T.H.M.

Aqueous solubilities, n-octanol/water partition coefficients (K{sub ow}S), and Henry`s law constants were determined for a range of polycyclic aromatic hydrocarbons (PAHs) using a generator-column, slow-stirring, and gas-purge method, respectively. The currently obtained data were compared to available literature data. For seven of the PAHs no K{sub ow}S previously were determined with the slow-stirring method. For four of the PAHs the present study reports the first experimental Henry`s law constants. Relationships between subcooled liquid solubilities, K{sub ow}S, and Henry`s law constants as a function of molar volume are discussed. A consistent data set was obtained, for which an excellent correlation wasmore » found between subcooled liquid solubility and molar volume. A linear fit did not accurately describe the relationship between log K{sub ow} and molar volume. This is probably due to a decreasing solubility in n-octanol with increasing molar volume. Finally, a high correlation was found between Henry`s law constant and molar volume. The presently obtained dataset can be used to predict the fate and behavior of unsubstituted homocyclic PAHs.« less

Review of lattice results concerning low-energy particle physics

DOE PAGES

Aoki, S.; Aoki, Y.; Bernard, C.; ...

2014-09-01

We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle physics community. More specifically, we report on the determination of the light-quark masses, the form factor f+(0), arising in semileptonic K -> pi transition at zero momentum transfer, as well as the decay constant ratio fK/fpi of decay constants and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)LxSU(2)R and SU(3)LxSU(3)R Chiral Perturbation Theory and review the determination ofmore » the BK parameter of neutral kaon mixing. The inclusion of heavy-quark quantities significantly expands the FLAG scope with respect to the previous review. Therefore, for this review, we focus on D- and B-meson decay constants, form factors, and mixing parameters, since these are most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. In addition we review the status of lattice determinations of the strong coupling constant alpha_s.« less

Cl(-) concentration dependence of photovoltage generation by halorhodopsin from Halobacterium salinarum.

PubMed Central

Muneyuki, Eiro; Shibazaki, Chie; Wada, Yoichiro; Yakushizin, Manabu; Ohtani, Hiroyuki

2002-01-01

The photovoltage generation by halorhodopsin from Halobacterium salinarum (shR) was examined by adsorbing shR-containing membranes onto a thin polymer film. The photovoltage consisted of two major components: one with a sub-millisecond range time constant and the other with a millisecond range time constant with different amplitudes, as previously reported. These components exhibited different Cl(-) concentration dependencies (0.1-9 M). We found that the time constant for the fast component was relatively independent of the Cl(-) concentration, whereas the time constant for the slow component increased sigmoidally at higher Cl(-) concentrations. The fast and the slow processes were attributed to charge (Cl(-)) movements within the protein and related to Cl(-) ejection, respectively. The laser photolysis studies of shR-membrane suspensions revealed that they corresponded to the formation and the decay of the N intermediate. The photovoltage amplitude of the slow component exhibited a distorted bell-shaped Cl(-) concentration dependence, and the Cl(-) concentration dependence of its time constant suggested a weak and highly cooperative Cl(-)-binding site(s) on the cytoplasmic side (apparent K(D) of approximately 5 M and Hill coefficient > or =5). The Cl(-) concentration dependence of the photovoltage amplitude and the time constant for the slow process suggested a competition between spontaneous relaxation and ion translocation. The time constant for the relaxation was estimated to be >100 ms. PMID:12324398

Nuclear-spin optical rotation in xenon

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

Savukov, Igor Mykhaylovich

We report that the nuclear-spin optical rotation (NSOR) effect, which has potential applications in correlated nuclear-spin-resonance optical spectroscopy, has previously been explored experimentally and theoretically in liquid Xe. Calculations of the Xe NSOR constant are very challenging because the result is sensitive to correlations, relativistic effects, and the choice of basis, with strong cancellation between contributions from lowest and remaining states. The relativistic configuration-interaction many-body-theory approach, presented here, is promising because this approach has been successful in predicting various properties of noble-gas atoms, such as energies, oscillator strengths (OSs), Verdet constants, and photoionization cross sections. However, correlations become stronger alongmore » the sequence of noble-gas atoms and the theoretical accuracy in Xe is not as high as, for example, in neon and argon. To improve the accuracy of the Xe Verdet and NSOR constants, which are calculated as explicit sums over the excited states, theoretical values for the several lowest levels are replaced with empirical values of energies, OSs, and hyperfine structure constants. We found that the Xe Verdet constant is in excellent agreement with accurate measurements. To take into account liquid effects, empirical data for energy shifts were also used to correct the NSOR constant. In conclusion, the resulting Xe NSOR constant is in a good agreement with experiment, although the liquid-state effect is treated quite approximately.« less

Nuclear-spin optical rotation in xenon

DOE PAGES

Savukov, Igor Mykhaylovich

2015-10-29

We report that the nuclear-spin optical rotation (NSOR) effect, which has potential applications in correlated nuclear-spin-resonance optical spectroscopy, has previously been explored experimentally and theoretically in liquid Xe. Calculations of the Xe NSOR constant are very challenging because the result is sensitive to correlations, relativistic effects, and the choice of basis, with strong cancellation between contributions from lowest and remaining states. The relativistic configuration-interaction many-body-theory approach, presented here, is promising because this approach has been successful in predicting various properties of noble-gas atoms, such as energies, oscillator strengths (OSs), Verdet constants, and photoionization cross sections. However, correlations become stronger alongmore » the sequence of noble-gas atoms and the theoretical accuracy in Xe is not as high as, for example, in neon and argon. To improve the accuracy of the Xe Verdet and NSOR constants, which are calculated as explicit sums over the excited states, theoretical values for the several lowest levels are replaced with empirical values of energies, OSs, and hyperfine structure constants. We found that the Xe Verdet constant is in excellent agreement with accurate measurements. To take into account liquid effects, empirical data for energy shifts were also used to correct the NSOR constant. In conclusion, the resulting Xe NSOR constant is in a good agreement with experiment, although the liquid-state effect is treated quite approximately.« less

Adaptation of vestibular signals for self-motion perception

PubMed Central

St George, Rebecca J; Day, Brian L; Fitzpatrick, Richard C

2011-01-01

A fundamental concern of the brain is to establish the spatial relationship between self and the world to allow purposeful action. Response adaptation to unvarying sensory stimuli is a common feature of neural processing, both peripherally and centrally. For the semicircular canals, peripheral adaptation of the canal-cupula system to constant angular-velocity stimuli dominates the picture and masks central adaptation. Here we ask whether galvanic vestibular stimulation circumvents peripheral adaptation and, if so, does it reveal central adaptive processes. Transmastoidal bipolar galvanic stimulation and platform rotation (20 deg s−1) were applied separately and held constant for 2 min while perceived rotation was measured by verbal report. During real rotation, the perception of turn decayed from the onset of constant velocity with a mean time constant of 15.8 s. During galvanic-evoked virtual rotation, the perception of rotation initially rose but then declined towards zero over a period of ∼100 s. For both stimuli, oppositely directed perceptions of similar amplitude were reported when stimulation ceased indicating signal adaptation at some level. From these data the time constants of three independent processes were estimated: (i) the peripheral canal-cupula adaptation with time constant 7.3 s, (ii) the central ‘velocity-storage’ process that extends the afferent signal with time constant 7.7 s, and (iii) a long-term adaptation with time constant 75.9 s. The first two agree with previous data based on constant-velocity stimuli. The third component decayed with the profile of a real constant angular acceleration stimulus, showing that the galvanic stimulus signal bypasses the peripheral transformation so that the brainstem sees the galvanic signal as angular acceleration. An adaptive process involving both peripheral and central processes is indicated. Signals evoked by most natural movements will decay peripherally before adaptation can exert an appreciable effect, making a specific vestibular behavioural role unlikely. This adaptation appears to be a general property of the internal coding of self-motion that receives information from multiple sensory sources and filters out the unvarying components regardless of their origin. In this instance of a pure vestibular sensation, it defines the afferent signal that represents the stationary or zero-rotation state. PMID:20937715

IR spectra and properties of solid acetone, an interstellar and cometary molecule

NASA Astrophysics Data System (ADS)

Hudson, Reggie L.; Gerakines, Perry A.; Ferrante, Robert F.

2018-03-01

Mid-infrared spectra of amorphous and crystalline acetone are presented along with measurements of the refractive index and density for both forms of the compound. Infrared band strengths are reported for the first time for amorphous and crystalline acetone, along with IR optical constants. Vapor pressures and a sublimation enthalpy for crystalline acetone also are reported. Positions of 13C-labeled acetone are measured. Band strengths are compared to gas-phase values and to the results of a density-functional calculation. A 73% error in previous work is identified and corrected.

Cosmological Implications of the Effects of X-Ray Clusters on the Cosmic Microwave Background

NASA Technical Reports Server (NTRS)

Forman, William R.

1996-01-01

We have been carrying forward a program to confront X-ray observations of clusters and their evolution as derived from X-ray observatories with observations of the cosmic microwave background radiation (CMBR). In addition to the material covered in our previous reports (including three published papers), most recently we have explored the effects of a cosmological constant on the predicted Sunyaev-Zel'dovich effect from the ensemble of clusters. In this report we summarize that work from which a paper will be prepared.

Hydride Transfer in DHFR by Transition Path Sampling, Kinetic Isotope Effects, and Heavy Enzyme Studies

PubMed Central

Wang, Zhen; Antoniou, Dimitri; Schwartz, Steven D.; Schramm, Vern L.

2016-01-01

Escherichia coli dihydrofolate reductase (ecDHFR) is used to study fundamental principles of enzyme catalysis. It remains controversial whether fast protein motions are coupled to the hydride transfer catalyzed by ecDHFR. Previous studies with heavy ecDHFR proteins labeled with 13C, 15N, and nonexchangeable 2H reported enzyme mass-dependent hydride transfer kinetics for ecDHFR. Here, we report refined experimental and computational studies to establish that hydride transfer is independent of protein mass. Instead, we found the rate constant for substrate dissociation to be faster for heavy DHFR. Previously reported kinetic differences between light and heavy DHFRs likely arise from kinetic steps other than the chemical step. This study confirms that fast (femtosecond to picosecond) protein motions in ecDHFR are not coupled to hydride transfer and provides an integrative computational and experimental approach to resolve fast dynamics coupled to chemical steps in enzyme catalysis. PMID:26652185

Calculation of the rate constant for state-selected recombination of H+O2(v) as a function of temperature and pressure

NASA Astrophysics Data System (ADS)

Teitelbaum, Heshel; Caridade, Pedro J. S. B.; Varandas, António J. C.

2004-06-01

Classical trajectory calculations using the MERCURY/VENUS code have been carried out on the H+O2 reactive system using the DMBE-IV potential energy surface. The vibrational quantum number and the temperature were selected over the ranges v=0 to 15, and T=300 to 10 000 K, respectively. All other variables were averaged. Rate constants were determined for the energy transfer process, H+O2(v)-->H+O2(v''), for the bimolecular exchange process, H+O2(v)-->OH(v')+O, and for the dissociative process, H+O2(v)-->H+O+O. The dissociative process appears to be a mere extension of the process of transferring large amounts of energy. State-to-state rate constants are given for the exchange reaction, and they are in reasonable agreement with previous results, while the energy transfer and dissociative rate constants have never been reported previously. The lifetime distributions of the HO2 complex, calculated as a function of v and temperature, were used as a basis for determining the relative contributions of various vibrational states of O2 to the thermal rate coefficients for recombination at various pressures. This novel approach, based on the complex's ability to survive until it collides in a secondary process with an inert gas, is used here for the first time. Complete falloff curves for the recombination of H+O2 are also calculated over a wide range of temperatures and pressures. The combination of the two separate studies results in pressure- and temperature-dependent rate constants for H+O2(v)(+Ar)⇄HO2(+Ar). It is found that, unlike the exchange reaction, vibrational and rotational-translational energy are liabilities in promoting recombination.

Utilizing Calibrated GPS Reflected Signals to Estimate Soil Reflectivity and Dielectric Constant: Results from SMEX02

NASA Technical Reports Server (NTRS)

Katzberg, Stephen J.; Torres, Omar; Grant, Michael S.; Masters, Dallas

2006-01-01

Extensive reflected GPS data was collected using a GPS reflectometer installed on an HC130 aircraft during the Soil Moisture Experiment 2002 (SMEX02) near Ames, Iowa. At the same time, widespread surface truth data was acquired in the form of point soil moisture profiles, areal sampling of near-surface soil moisture, total green biomass and precipitation history, among others. Previously, there have been no reported efforts to calibrate reflected GPS data sets acquired over land. This paper reports the results of two approaches to calibration of the data that yield consistent results. It is shown that estimating the strength of the reflected signals by either (1) assuming an approximately specular surface reflection or (2) inferring the surface slope probability density and associated normalization constants give essentially the same results for the conditions encountered in SMEX02. The corrected data is converted to surface reflectivity and then to dielectric constant as a test of the calibration approaches. Utilizing the extensive in-situ soil moisture related data this paper also presents the results of comparing the GPS-inferred relative dielectric constant with the Wang-Schmugge model frequently used to relate volume moisture content to dielectric constant. It is shown that the calibrated GPS reflectivity estimates follow the expected dependence of permittivity with volume moisture, but with the following qualification: The soil moisture value governing the reflectivity appears to come from only the top 1-2 centimeters of soil, a result consistent with results found for other microwave techniques operating at L-band. Nevertheless, the experimentally derived dielectric constant is generally lower than predicted. Possible explanations are presented to explain this result.

A test method for determining adhesion forces and Hamaker constants of cementitious materials using atomic force microscopy

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

Lomboy, Gilson; Sundararajan, Sriram, E-mail: srirams@iastate.edu; Wang Kejin

2011-11-15

A method for determining Hamaker constant of cementitious materials is presented. The method involved sample preparation, measurement of adhesion force between the tested material and a silicon nitride probe using atomic force microscopy in dry air and in water, and calculating the Hamaker constant using appropriate contact mechanics models. The work of adhesion and Hamaker constant were computed from the pull-off forces using the Johnson-Kendall-Roberts and Derjagin-Muller-Toropov models. Reference materials with known Hamaker constants (mica, silica, calcite) and commercially available cementitious materials (Portland cement (PC), ground granulated blast furnace slag (GGBFS)) were studied. The Hamaker constants of the reference materialsmore » obtained are consistent with those published by previous researchers. The results indicate that PC has a higher Hamaker constant than GGBFS. The Hamaker constant of PC in water is close to the previously predicted value C{sub 3}S, which is attributed to short hydration time ({<=} 45 min) used in this study.« less

Sub-Micrometer Zeolite Films on Gold-Coated Silicon Wafers with Single-Crystal-Like Dielectric Constant and Elastic Modulus

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

Tiriolo, Raffaele; Rangnekar, Neel; Zhang, Han

A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a non-thermal photochemical activation to ensure preservationmore » of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal-insulator-metal configuration, highlights the ultralow k approximate to 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E approximate to 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.« less

Rate constant for OH with selected large alkanes : shock-tube measurements and an improved group scheme.

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

Sivaramakrishnan, R.; Michael, J. V.; Chemical Sciences and Engineering Division

High-temperature rate constant experiments on OH with the five large (C{sub 5}-C{sub 8}) saturated hydrocarbons n-heptane, 2,2,3,3-tetramethylbutane (2,2,3,3-TMB), n-pentane, n-hexane, and 2,3-dimethylbutane (2,3-DMB) were performed with the reflected-shock-tube technique using multipass absorption spectrometric detection of OH radicals at 308 nm. Single-point determinations at {approx}1200 K on n-heptane, 2,2,3,3-TMB, n-hexane, and 2,3-DMB were previously reported by Cohen and co-workers; however, the present work substantially extends the database to both lower and higher temperature. The present experiments span a wide temperature range, 789-1308 K, and represent the first direct measurements of rate constants at T > 800 K for n-pentane. The presentmore » work utilized 48 optical passes corresponding to a total path length of {approx}4.2 m. As a result of this increased path length, the high OH concentration detection sensitivity permitted pseudo-first-order analyses for unambiguously measuring rate constants.« less

JPRS Report, West Europe.

DTIC Science & Technology

1988-02-03

hint interestingly at current moods, especially if the data are combined with other surveys conducted by Economy Research, Inc., for UUSI SUOMI in...likewise a problem, especially if a long time has elapsed since the previous election. Comparison is also made difficult by different-sized samples... especially , for worse; all of them are awaiting their chance. And that fact—that is, the existence of a majority composed of men who are constantly

Heat makes a difference in activity-based anorexia: a translational approach to treatment development in anorexia nervosa.

PubMed

Cerrato, Maria; Carrera, Olaia; Vazquez, Reyes; Echevarría, Enrique; Gutierrez, Emilio

2012-01-01

To test the effect of raising ambient temperature (AT) on activity-based anorexia (ABA) and to extend to female rats previous findings reported in male animals. Two studies are reported in which female rats were submitted to food restriction and free access to an activity wheel either separately or in combination under changing (21-32 °C) or constant AT (21 °C). Warming ABA animals reversed running activity, preserved food-intake, and enabled female rats to recover from acute weight loss. Moreover, sedentary food-restricted warmed rats maintained a body weight equivalent to the levels of animals housed at standard AT in spite of 20% reduced food-intake. The replication on female rats corroborates the effect previously reported for males, which is indicative of the robust effect of AT in recovering rats from ABA. The findings reported here represent strong preclinical evidence in favor of heat supply as a useful adjunctive component for the treatment of anorexia nervosa (AN). Copyright © 2010 Wiley Periodicals, Inc.

Pain and alcohol consumption among older adults: findings from the World Health Organization Study on global AGEing and adult health, Wave 1.

PubMed

Ahangari, Alebtekin; Stewart Williams, Jennifer; Myléus, Anna

2016-10-01

To investigate cross-sectional associations between self-reported recent pain and alcohol use/abstinence, and previous-day pain and previous-week alcohol consumption in adults aged 50 + in six low- and middle-income countries (LMICs). The WHO Study on global AGEing and adult health (SAGE) Wave 1 (2007-2010) in China, Ghana, India, Mexico, Russia and South Africa is the data source. Prevalence of alcohol use/abstinence is reported by previous-day and previous-month pain. Multinomial logistic regressions (crude and adjusted for sex and country) tested associations between recent pain and alcohol use in the pooled multicountry sample. Across the six SAGE countries, about one-third of respondents reported alcohol use, being highest in Russia (74%) and lowest in India (16%). Holding the effects of sex and country constant, compared with abstainers, people with previous-day pain were more likely to be previous-day or other users. With regard to the quantity and frequency of alcohol use, people with previous-day pain were more likely to be non-heavy drinkers. Overall, we found that, in this population of older adults in six LMICs, recent pain was associated with moderate use of alcohol, although there were differences between countries. The findings provide a platform for country-specific research to better understand bi-directional associations between pain and alcohol in older adults. © 2016 John Wiley & Sons Ltd.

Oxidation of CO by N/sub 2/O between 1076 and 1228 K: determination of the rate constant of the exchange reaction

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

Loirat, H.; Caralp, F.; Destriau, M.

New measurements of the rate constant of the direct reaction of CO with N/sub 2/O are reported with the principal purpose of removing some of the remaining discrepancies on its value. Experiments were performed at lower temperatures (1076-1228 K) and lower pressure (approx. 15 Torr) than those prevailing in most of previous works, by using a static reactor. It is shown that, under these experimental conditions, the reaction proceeds essentially according to the direct reaction CO + N/sub 2/O ..-->.. CO/sub 2/ + N/sub 2/ (1). The previously proposed wet mechanism is not significant under our experimental conditions. It hasmore » to be taken into account, however, to describe the observed production and consumption of molecular oxygen. The Arrhenius expression derived from these experiments is k/sub 1/ = 10/sup 14.4 +/- 0.3 exp(-(46 +- 2) kcal mol/sup -1/RT) cm/sup 3/ mol/sup -1/ s/sup -1/. A detailed analysis of the results shows that the uncertainties in side reactions do not greatly influence the value of k/sub 1/. A critical discussion of the data reported in the literature is presented. In spite of remaining uncertainties in the reaction mechanism, the present results, obtained in a low-temperature range, show that the low activation energy values of reaction 1, reported in several works performed at higher temperatures, are highly unlikely« less

Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J·cm−3

PubMed Central

Cortes, Francisco Javier Quintero; Phillips, Jonathan

2015-01-01

The construction and performance of a second generation of super dielectric material based electrostatic capacitors (EC), with energy density greater than 200 J·cm−3, which rival the best reported energy density of electric double layer capacitors (EDLC), also known as supercapacitors, are reported. The first generation super dielectric materials (SDM) are multi-material mixtures with dielectric constants greater than 1.0 × 105, composed of a porous, electrically insulating powder filled with a polarizable, ion-containing liquid. Second-generation SDMs (TSDM), introduced here, are anodic titania nanotube arrays filled with concentrated aqueous salt solutions. Capacitors using TiO2 based TSDM were found to have dielectric constants at ~0 Hz greater than 107 in all cases, a maximum operating voltage of greater than 2 volts and remarkable energy density that surpasses the highest previously reported for EC capacitors by approximately one order of magnitude. A simple model based on the classic ponderable media model was shown to be largely consistent with data from nine EC type capacitors employing TSDM. PMID:28793561

Tube-Super Dielectric Materials: Electrostatic Capacitors with Energy Density Greater than 200 J·cm-3.

PubMed

Cortes, Francisco Javier Quintero; Phillips, Jonathan

2015-09-17

The construction and performance of a second generation of super dielectric material based electrostatic capacitors (EC), with energy density greater than 200 J·cm - ³, which rival the best reported energy density of electric double layer capacitors (EDLC), also known as supercapacitors, are reported. The first generation super dielectric materials (SDM) are multi-material mixtures with dielectric constants greater than 1.0 × 10⁵, composed of a porous, electrically insulating powder filled with a polarizable, ion-containing liquid. Second-generation SDMs (TSDM), introduced here, are anodic titania nanotube arrays filled with concentrated aqueous salt solutions. Capacitors using TiO₂ based TSDM were found to have dielectric constants at ~0 Hz greater than 10⁷ in all cases, a maximum operating voltage of greater than 2 volts and remarkable energy density that surpasses the highest previously reported for EC capacitors by approximately one order of magnitude. A simple model based on the classic ponderable media model was shown to be largely consistent with data from nine EC type capacitors employing TSDM.

High temperature tensile properties of V-4Cr-4Ti

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

Zinkle, S.J.; Rowcliffe, A.F.; Stevens, C.O.

Tensile tests have been performed on V-4Cr-4Ti at 750 and 800 C in order to extend the data base beyond the current limit of 700 C. From comparison with previous measurements, the yield strength is nearly constant and tensile elongations decrease slightly with increasing temperature between 300 and 800 C. The ultimate strength exhibits an apparent maximum near 600 C (attributable to dynamic strain aging) but adequate strength is maintained up to 800 C. The reduction in area measured on tensile specimens remained high ({approximately}80%) for test temperatures up to 800 C, in contrast to previous reported results.

Present status of astronomical constants

NASA Astrophysics Data System (ADS)

Fukushima, T.

Given was the additional information to the previous report on the recent progress in the determinations of astronomical constants (Fukushima 2000). First noted was the revision of LG as 6.969290134×10-10 based on the proposal to shift its status from a primary to a defining constant (Petit 2000). Next focused was the significant update of the correction to the current precession constant, Δp, based on the recent LLR-based determination (Chapront et al. 2000) as -0.3164+/-0.0030"/cy. By combining this and the equal weighted average of VLBI determinations (Mathews et al. 2000; Petrov 2000; Shirai and Fukushima 2000; Vondrak and Ron 2000) as -0.2968+/-0.0043"/cy, we derived the best estimate of precession constant as p = 5028.790+/-0.005"/cy. Also redetermined were some other quantities related to the precession formula; namely the offsets of Celestial Ephemeris Pole of the International Celestial Reference System as &Deltaψ0sinɛ0 = (-17.0+/-0.3) mas and Δɛ0 = (-5.1+/-0.3) mas. As a result, the obliquity of the ecliptic at the epoch J2000.0 was estimated as ɛ0 = 23°26'21."4059+/-0."0003. As a summary, presented was the (revised) IAU 2000 File of Current Best Estimates of astronomical constants, which is to replace the former 1994 version (Standish 1995).

Effect of expansions in state Medicaid eligibility on access to care and the use of emergency department services for adult Medicaid enrollees.

PubMed

Ndumele, Chima D; Mor, Vincent; Allen, Susan; Burgess, James F; Trivedi, Amal N

2014-06-01

Medicaid enrollees typically report worse access to care than other insured populations. Expansions in Medicaid through less restrictive income eligibility requirements and the resulting influx of new enrollees may further erode access to care for those already enrolled in Medicaid. To assess the effect of previous Medicaid expansions on self-reported access to care and the use of emergency department services by Medicaid enrollees. Quasi-experimental difference-in-differences design among 1714 adult Medicaid enrollees in 10 states that expanded Medicaid between June 1, 2000, and October 1, 2009, and 5097 Medicaid enrollees in 14 bordering control states that did not expand Medicaid. Self-reported access to care and annualized emergency department use. Among states expanding their Medicaid program for adults, the mean income eligibility level increased from 82.6% to 144.2% of the federal poverty level. Income eligibility in matched control states remained constant at 77.1% of the federal poverty level. The proportion of adults reporting being enrolled in Medicaid increased from 7.2% to 8.8% in expansion states and from 6.1% to 6.4% in matched control states. In Medicaid program expansion states, the proportion of Medicaid enrollees reporting poor access to care declined from 8.5% before the expansion to 7.3% after the expansion. In matched control states, the proportion of Medicaid enrollees reporting poor access to care remained constant at 5.3%. The proportion of enrollees reporting any emergency department use decreased from 41.2% to 40.1% in expansion states and from 37.3% to 36.1% in matched control states. In the period following expansions, newly eligible enrollees reported poorer access to care than previously enrolled beneficiaries, although the overall difference between groups did not reach statistical significance. We found no evidence that expanding the number of individuals eligible for Medicaid coverage eroded perceived access to care or increased the use of emergency services among adult Medicaid enrollees.

Synaptic Plasticity and Memory Formation

DTIC Science & Technology

1994-05-31

manipulations affected the waveform of the isolated response: i) a drug ( aniracetam ) known to prolong the mean open time of the receptors, ii) LTP and iii...LTP and aniracetam combined. In agreement with our previous reports, LTP was found to produce a characteristic distortion of the waveform of the... aniracetam and LTP was readily accounted for by the computer simulation of the AMPA receptor when LTP was modelled as an increase in the rate constants

The battle against violence in U.S. hospitals: an analysis of the recent I IAHSS Foundation's healthcare crime surveys.

PubMed

Vellani, Karim H

2016-10-01

In this article, the author analyzes the possible reasons for the reported drop in hospital violence in the 2016IAHSS Crime Survey compared to previous surveys. He also reviews the one statistic that has remained constant in all the recent crime surveys and recommends an approach in violence prevention programs that may prove successful in reducing workplace violence and staff injuries.

Concerning the flow about ring-shaped cowlings Part II : annular bodies of infinite length with circulation for smooth entrance

NASA Technical Reports Server (NTRS)

Kuchemann, Dietrich; Weber, Johanna

1951-01-01

The investigations carried out in a previous report (NACA TM 1325) concerning the flow about ring-shaped cowlings were extended by taking a circulation about the cowling into consideration. The present second report treats bodies of infinite length with approximately smooth entrance. The circulation was caused by distributing vortex rings of constant density over a stream surface extending to infinity. Furthermore, the influence of a hub body on such cowlings was dealt with. The examples treated are meant to give the designer a basis for his design.

Precise Measurements of the Masses of Cs, Rb and Na A New Route to the Fine Structure Constant

NASA Astrophysics Data System (ADS)

Rainville, Simon; Bradley, Michael P.; Porto, James V.; Thompson, James K.; Pritchard, David E.

2001-01-01

We report new values for the atomic masses of the alkali 133Cs, 87Rb, 85Rb, and 23Na with uncertainties ≤ 0.2 ppb. These results, obtained using Penning trap single ion mass spectrometry, are typically two orders of magnitude more accurate than previously measured values. Combined with values of h/m atom from atom interferometry measurements and accurate wavelength measurements for different atoms, these values will lead to new ppb-level determinations of the molar Planck constant N A h and the fine structure constant α. This route to α is based on simple physics. It can potentially achieve the several ppb level of accuracy needed to test the QED determination of α extracted from measurements of the electron g factor. We also demonstrate an electronic cooling technique that cools our detector and ion below the 4 K ambient temperature. This technique improves by about a factor of three our ability to measure the ion's axial motion.

Doppler-resolved kinetics of saturation recovery

DOE PAGES

Forthomme, Damien; Hause, Michael L.; Yu, Hua -Gen; ...

2015-04-08

Frequency modulated laser transient absorption has been used to monitor the ground state rotational energy transfer rates of CN radicals in a double-resonance, depletion recovery experiment. When a pulsed laser is used to burn a hole in the equilibrium ground state population of one rotational state without velocity selection, the population recovery rate is found to depend strongly on the Doppler detuning of a narrow-band probe laser. Similar effects should be apparent for any relaxation rate process that competes effectively with velocity randomization. Alternative methods of extracting thermal rate constants in the presence of these non-thermal conditions are evaluated. Totalmore » recovery rate constants, analogous to total removal rate constants in an experiment preparing a single initial rotational level, are in good agreement with quantum scattering calculations, but are slower than previously reported experiments and show qualitatively different rotational state dependence between Ar and He collision partners. As a result, quasi-classical trajectory studies confirm that the differing rotational state dependence is primarily a kinematic effect.« less

Three dielectric constants and orientation order parameters in nematic mesophases

NASA Astrophysics Data System (ADS)

Yoon, Hyung Guen; Jeong, Seung Yeon; Kumar, Satyendra; Park, Min Sang; Park, Jung Ok; Srinivasarao, M.; Shin, Sung Tae

2011-03-01

Temperature dependence of the three components ɛ1 , ɛ2 , and ɛ3 of dielectric constant and orientation order parameters in the nematic phase of mesogens with rod, banana, and zero-order dendritic shape were measured using the in-plane and vertical switching geometries, and micro-Raman technique. Results on the well-known uniaxial (Nu) nematogens, E7 and 5CB, revealed two components ɛ1 = ~ɛ| | and ɛ2 = ~ɛ3 = ~ɛ⊥ , as expected. The three dielectric constants were different for two azo substituted (A131 and A103) and an oxadiazole based (ODBP-Ph-C12) bent core mesogens, and a Ge core tetrapode. In some cases, two of the components became the same indicating a loss of biaxiality at temperatures coinciding with the previously reported Nu to biaxial nematic transition. This interpretation is substantiated by micro-Raman measurements of the uniaxial and biaxial nematic order parameters. Supported by the US Department of Energy, Basic Energy Sciences grant ER46572 and by Samsung Electronics Corporation.

Role of deuterium desorption kinetics on the thermionic emission properties of polycrystalline diamond films with respect to kinetic isotope effects

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

Paxton, W. F., E-mail: william.f.paxton@vanderbilt.edu; Howell, M.; Kang, W. P.

2014-06-21

The desorption kinetics of deuterium from polycrystalline chemical vapor deposited diamond films were characterized by monitoring the isothermal thermionic emission current behavior. The reaction was observed to follow a first-order trend as evidenced by the decay rate of the thermionic emission current over time which is in agreement with previously reported studies. However, an Arrhenius plot of the reaction rates at each tested temperature did not exhibit the typical linear behavior which appears to contradict past observations of the hydrogen (or deuterium) desorption reaction from diamond. This observed deviation from linearity, specifically at lower temperatures, has been attributed to non-classicalmore » processes. Though no known previous studies reported similar deviations, a reanalysis of the data obtained in the present study was performed to account for tunneling which appeared to add merit to this hypothesis. Additional investigations were performed by reevaluating previously reported data involving the desorption of hydrogen (as opposed to deuterium) from diamond which further indicated this reaction to be dominated by tunneling at the temperatures tested in this study (<775 °C). An activation energy of 3.19 eV and a pre-exponential constant of 2.3 × 10{sup 12} s{sup −1} were determined for the desorption reaction of deuterium from diamond which is in agreement with previously reported studies.« less

User Guide for Compressible Flow Toolbox Version 2.1 for Use With MATLAB(Registered Trademark); Version 7

NASA Technical Reports Server (NTRS)

Melcher, Kevin J.

2006-01-01

This report provides a user guide for the Compressible Flow Toolbox, a collection of algorithms that solve almost 300 linear and nonlinear classical compressible flow relations. The algorithms, implemented in the popular MATLAB programming language, are useful for analysis of one-dimensional steady flow with constant entropy, friction, heat transfer, or shock discontinuities. The solutions do not include any gas dissociative effects. The toolbox also contains functions for comparing and validating the equation-solving algorithms against solutions previously published in the open literature. The classical equations solved by the Compressible Flow Toolbox are: isentropic-flow equations, Fanno flow equations (pertaining to flow of an ideal gas in a pipe with friction), Rayleigh flow equations (pertaining to frictionless flow of an ideal gas, with heat transfer, in a pipe of constant cross section.), normal-shock equations, oblique-shock equations, and Prandtl-Meyer expansion equations. At the time this report was published, the Compressible Flow Toolbox was available without cost from the NASA Software Repository.

Nonlinear elastic response of strong solids: First-principles calculations of the third-order elastic constants of diamond

DOE PAGES

Hmiel, A.; Winey, J. M.; Gupta, Y. M.; ...

2016-05-23

Accurate theoretical calculations of the nonlinear elastic response of strong solids (e.g., diamond) constitute a fundamental and important scientific need for understanding the response of such materials and for exploring the potential synthesis and design of novel solids. However, without corresponding experimental data, it is difficult to select between predictions from different theoretical methods. Recently the complete set of third-order elastic constants (TOECs) for diamond was determined experimentally, and the validity of various theoretical approaches to calculate the same may now be assessed. We report on the use of density functional theory (DFT) methods to calculate the six third-order elasticmore » constants of diamond. Two different approaches based on homogeneous deformations were used: (1) an energy-strain fitting approach using a prescribed set of deformations, and (2) a longitudinal stress-strain fitting approach using uniaxial compressive strains along the [100], [110], and [111] directions, together with calculated pressure derivatives of the second-order elastic constants. The latter approach provides a direct comparison to the experimental results. The TOECs calculated using the energy-strain approach differ significantly from the measured TOECs. In contrast, calculations using the longitudinal stress-uniaxial strain approach show good agreement with the measured TOECs and match the experimental values significantly better than the TOECs reported in previous theoretical studies. Lastly, our results on diamond have demonstrated that, with proper analysis procedures, first-principles calculations can indeed be used to accurately calculate the TOECs of strong solids.« less

A GAS-PHASE FORMATION ROUTE TO INTERSTELLAR TRANS-METHYL FORMATE

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

Cole, Callie A.; Wehres, Nadine; Yang Zhibo

2012-07-20

The abundance of methyl formate in the interstellar medium has previously been underpredicted by chemical models. Additionally, grain surface chemistry cannot account for the relative abundance of the cis- and trans-conformers of methyl formate, and the trans-conformer is not even formed at detectable abundance on these surfaces. This highlights the importance of studying formation pathways to methyl formate in the gas phase. The rate constant and branching fractions are reported for the gas-phase reaction between protonated methanol and formic acid to form protonated trans-methyl formate and water as well as adduct ion: Rate constants were experimentally determined using a flowingmore » afterglow-selected ion flow tube apparatus at 300 K and a pressure of 530 mTorr helium. The results indicate a moderate overall rate constant of (3.19 {+-} 0.39) Multiplication-Sign 10{sup -10} cm{sup 3} s{sup -1} ({+-} 1{sigma}) and an average branching fraction of 0.05 {+-} 0.04 for protonated trans-methyl formate and 0.95 {+-} 0.04 for the adduct ion. These experimental results are reinforced by ab initio calculations at the MP2(full)/aug-cc-pVTZ level of theory to examine the reaction coordinate and complement previous density functional theory calculations. This study underscores the need for continued observational studies of trans-methyl formate and for the exploration of other gas-phase formation routes to complex organic molecules.« less

Rate Constant and Reaction Coordinate of Trp-Cage Folding in Explicit Water

PubMed Central

Juraszek, Jarek; Bolhuis, Peter G.

2008-01-01

We report rate constant calculations and a reaction coordinate analysis of the rate-limiting folding and unfolding process of the Trp-cage mini-protein in explicit solvent using transition interface sampling. Previous transition path sampling simulations revealed that in this (un)folding process the protein maintains its compact configuration, while a (de)increase of secondary structure is observed. The calculated folding rate agrees reasonably with experiment, while the unfolding rate is 10 times higher. We discuss possible origins for this mismatch. We recomputed the rates with the forward flux sampling method, and found a discrepancy of four orders of magnitude, probably caused by the method's higher sensitivity to the choice of order parameter with respect to transition interface sampling. Finally, we used the previously computed transition path-sampling ensemble to screen combinations of many order parameters for the best model of the reaction coordinate by employing likelihood maximization. We found that a combination of the root mean-square deviation of the helix and of the entire protein was, of the set of tried order parameters, the one that best describes the reaction coordination. PMID:18676648

Measurement and Modeling of Setschenow Constants for Selected Hydrophilic Compounds in NaCl and CaCl2 Simulated Carbon Storage Brines.

PubMed

Burant, Aniela; Lowry, Gregory V; Karamalidis, Athanasios K

2017-06-20

Carbon capture, utilization, and storage (CCUS), a climate change mitigation strategy, along with unconventional oil and gas extraction, generates enormous volumes of produced water containing high salt concentrations and a litany of organic compounds. Understanding the aqueous solubility of organic compounds related to these operations is important for water treatment and reuse alternatives, as well as risk assessment purposes. The well-established Setschenow equation can be used to determine the effect of salts on aqueous solubility. However, there is a lack of reported Setschenow constants, especially for polar organic compounds. In this study, the Setschenow constants for selected hydrophilic organic compounds were experimentally determined, and linear free energy models for predicting the Setschenow constant of organic chemicals in concentrated brines were developed. Solid phase microextraction was employed to measure the salting-out behavior of six selected hydrophilic compounds up to 5 M NaCl and 2 M CaCl 2 and in Na-Ca-Cl brines. All compounds, which include phenol, p-cresol, hydroquinone, pyrrole, hexanoic acid, and 9-hydroxyfluorene, exhibited log-linear behavior up to these concentrations, meaning Setschenow constants previously measured at low salt concentrations can be extrapolated up to high salt concentrations for hydrophilic compounds. Setschenow constants measured in NaCl and CaCl 2 brines are additive for the compounds measured here; meaning Setschenow constants measured in single salt solutions can be used in multiple salt solutions. The hydrophilic compounds in this study were selected to elucidate differences in salting-out behavior based on their chemical structure. Using data from this study, as well as literature data, linear free energy relationships (LFERs) for prediction of NaCl, CaCl 2 , LiCl, and NaBr Setschenow constants were developed and validated. Two LFERs were improved. One LFER uses the Abraham solvation parameters, which include the index of refraction of the organic compound, organic compound's polarizability, hydrogen bonding acidity and basicity of the organic compound, and the molar volume of the compound. The other uses an octanol-water partitioning coefficient to predict NaCl Setschenow constants. Improved models from this study now include organic compounds that are structurally and chemically more diverse than the previous models. The CaCl 2 , LiCl, and NaBr single parameter LFERs use concepts from the Hofmeister series to predict new, respective Setschenow constants from NaCl Setschenow constants. The Setschenow constants determined here, as well as the LFERs developed, can be incorporated into CCUS reactive transport models to predict aqueous solubility and partitioning coefficients of organic compounds. This work also has implications for beneficial reuse of water from CCUS; this can aide in determining treatment technologies for produced waters.

O2(b1∑+g) relaxation in active medium of oxygen-iodine laser

NASA Astrophysics Data System (ADS)

Tolstov, G. I.; Zagidullin, M. V.; Khvatov, N. A.; Medvedkov, I. A.; Mikheyev, P. A.

2018-04-01

Rate constants for the removal of O2 b1∑+g by collisions with O2, N2, CO2 and H2O have been determined at temperature 297 K. O2(b1 ∑+g) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed by observing the temporal behavior of the b1∑+g - X3∑-g fluorescence. The removal rate constants for CO2, N2 and H2O were not strongly dependent on temperature, and could be represented by the expressions kCO2=(1.8+/-0.05)×10-16 kN2=(2.2 +/- 0.2)×10-15, and kH2O=(6.12+/-0.67)×10-12 cm3 molecule-1 s-1. Rate constant for O2(b1∑+ ) removal by O2(X), being orders of magnitude lower, represented by the fitted expression kO2=(3.67 +/- 0.06)×10-17 cm3 molecule-1 s-1. All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.

Shielding requirements for constant-potential diagnostic x-ray beams determined by a Monte Carlo calculation.

PubMed

Simpkin, D J

1989-02-01

A Monte Carlo calculation has been performed to determine the transmission of broad constant-potential x-ray beams through Pb, concrete, gypsum wallboard, steel and plate glass. The EGS4 code system was used with a simple broad-beam geometric model to generate exposure transmission curves for published 70, 100, 120 and 140-kVcp x-ray spectra. These curves are compared to measured three-phase generated x-ray transmission data in the literature and found to be reasonable. For calculation ease the data are fit to an equation previously shown to describe such curves quite well. These calculated transmission data are then used to create three-phase shielding tables for Pb and concrete, as well as other materials not available in Report No. 49 of the NCRP.

Magnetoelectric coupling of a magnetoelectric flux gate sensor in vibration noise circumstance

NASA Astrophysics Data System (ADS)

Chu, Zhaoqiang; Shi, Huaduo; Gao, Xiangyu; Wu, Jingen; Dong, Shuxiang

2018-01-01

A magnetoelectric (ME) flux gate sensor (MEFGS) consisting of piezoelectric PMN-PT single crystals and ferromagnetic amorphous alloy ribbon in a self-differential configuration is featured with the ability of weak magnetic anomaly detection. Here, we further investigated its ME coupling and magnetic field detection performance in vibration noise circumstance, including constant frequency, impact, and random vibration noise. Experimental results show that the ME coupling coefficient of MEFGS is as high as 5700 V/cm*Oe at resonant frequency, which is several orders magnitude higher than previously reported differential ME sensors. It was also found that under constant and impact vibration noise circumstance, the noise reduction and attenuation factor of MEFGS are over 17 and 85.7%, respectively. This work is important for practical application of MEFGS in real environment.

Indications of a spatial variation of the fine structure constant.

PubMed

Webb, J K; King, J A; Murphy, M T; Flambaum, V V; Carswell, R F; Bainbridge, M B

2011-11-04

We previously reported Keck telescope observations suggesting a smaller value of the fine structure constant α at high redshift. New Very Large Telescope (VLT) data, probing a different direction in the Universe, shows an inverse evolution; α increases at high redshift. Although the pattern could be due to as yet undetected systematic effects, with the systematics as presently understood the combined data set fits a spatial dipole, significant at the 4.2 σ level, in the direction right ascension 17.5 ± 0.9 h, declination -58 ± 9 deg. The independent VLT and Keck samples give consistent dipole directions and amplitudes, as do high and low redshift samples. A search for systematics, using observations duplicated at both telescopes, reveals none so far which emulate this result.

Weak-value amplification as an optimal metrological protocol

NASA Astrophysics Data System (ADS)

Alves, G. Bié; Escher, B. M.; de Matos Filho, R. L.; Zagury, N.; Davidovich, L.

2015-06-01

The implementation of weak-value amplification requires the pre- and postselection of states of a quantum system, followed by the observation of the response of the meter, which interacts weakly with the system. Data acquisition from the meter is conditioned to successful postselection events. Here we derive an optimal postselection procedure for estimating the coupling constant between system and meter and show that it leads both to weak-value amplification and to the saturation of the quantum Fisher information, under conditions fulfilled by all previously reported experiments on the amplification of weak signals. For most of the preselected states, full information on the coupling constant can be extracted from the meter data set alone, while for a small fraction of the space of preselected states, it must be obtained from the postselection statistics.

Guanidinoacetate methyltransferase (GAMT) deficiency: late onset of movement disorder and preserved expressive language.

PubMed

O'Rourke, Declan J; Ryan, Stephanie; Salomons, Gajja; Jakobs, Cornelis; Monavari, Ahmad; King, Mary D

2009-05-01

Guanidinoacetate methyltransferase (GAMT) deficiency is a disorder of creatine biosynthesis, characterized by early-onset learning disability and epilepsy in most affected children. Severe expressive language delay is a constant feature even in the mildest clinical phenotypes.We report the clinical, biochemical, imaging, and treatment data of two female siblings (18y and 13y) with an unusual phenotype of GAMT deficiency. The oldest sibling had subacute onset of a movement disorder at age 17 years, later than has been previously reported. The younger sibling had better language skills than previously described in this disorder. After treatment with creatine, arginine restriction and ornithine-supplemented diet, seizure severity and movement disorder were reduced but cognition did not improve. This report confirms that GAMT deficiency, a heterogeneous, potentially treatable disorder, detected by increased levels of guanidinoacetate in body fluids (e.g. plasma or urine) or by an abnormal creatine peak on magnetic resonance spectroscopy, should be considered in patients of any age with unexplained, apparently static learning disability and epilepsy.

1H, 13C and 19F NMR studies on fluorinated ethers

NASA Astrophysics Data System (ADS)

Balonga, P. E.; Kowalewski, V. J.; Contreras, R. H.

The enflurane and ethoxyflurane 1H, 13C and 19F NMR spectra are examined—including sign determination of FF and FH couplings—and considered in the light of previously reported results for methoxyflurane. Conformational differences between methoxyflurane and the former two molecules are indicated by through space FH coupling constants and by the nonequivalence of geminal fluorine nuclei. Populations of conformers about the CC bond are estimated.

Static Stretching Alters Neuromuscular Function and Pacing Strategy, but Not Performance during a 3-Km Running Time-Trial

PubMed Central

Damasceno, Mayara V.; Duarte, Marcos; Pasqua, Leonardo A.; Lima-Silva, Adriano E.; MacIntosh, Brian R.; Bertuzzi, Rômulo

2014-01-01

Purpose Previous studies report that static stretching (SS) impairs running economy. Assuming that pacing strategy relies on rate of energy use, this study aimed to determine whether SS would modify pacing strategy and performance in a 3-km running time-trial. Methods Eleven recreational distance runners performed a) a constant-speed running test without previous SS and a maximal incremental treadmill test; b) an anthropometric assessment and a constant-speed running test with previous SS; c) a 3-km time-trial familiarization on an outdoor 400-m track; d and e) two 3-km time-trials, one with SS (experimental situation) and another without (control situation) previous static stretching. The order of the sessions d and e were randomized in a counterbalanced fashion. Sit-and-reach and drop jump tests were performed before the 3-km running time-trial in the control situation and before and after stretching exercises in the SS. Running economy, stride parameters, and electromyographic activity (EMG) of vastus medialis (VM), biceps femoris (BF) and gastrocnemius medialis (GA) were measured during the constant-speed tests. Results The overall running time did not change with condition (SS 11:35±00:31 s; control 11:28±00:41 s, p = 0.304), but the first 100 m was completed at a significantly lower velocity after SS. Surprisingly, SS did not modify the running economy, but the iEMG for the BF (+22.6%, p = 0.031), stride duration (+2.1%, p = 0.053) and range of motion (+11.1%, p = 0.0001) were significantly modified. Drop jump height decreased following SS (−9.2%, p = 0.001). Conclusion Static stretch impaired neuromuscular function, resulting in a slow start during a 3-km running time-trial, thus demonstrating the fundamental role of the neuromuscular system in the self-selected speed during the initial phase of the race. PMID:24905918

Computation of Nonretarded London Dispersion Coefficients and Hamaker Constants of Copper Phthalocyanine.

PubMed

Zhao, Yan; Ng, Hou T; Hanson, Eric; Dong, Jiannan; Corti, David S; Franses, Elias I

2010-02-09

A time-dependent density functional theory (TDDFT) scheme has been validated for predictions of the dispersion coefficients of five molecules (H2O, NH3, CO2, C6H6, and pentane) and for predictions of the static dipole polarizabilities of three organometallic compounds (TiCl4, OsO4, and Ge(CH3)4). The convergence of grid spacing has been examined, and two types of pseudopotentials and 13 density functionals have been tested. The nonretarded Hamaker constants A11 are calculated by employing a semiempirical parameter a along with the standard Hamaker constant equation. The parameter a is optimized against six accurate Hamaker constants obtained from the full Lifshitz theory. The dispersion coefficients of copper phthalocyanine CuPc and CuPc-SO3H are then computed. Using the theoretical densities of ρ1 = 1.63 and 1.62 g/cm(3), the Hamaker constants A11 of crystalline α-CuPc and β-CuPc are found to be 14.73 × 10(-20) and 14.66 × 10(-20) J, respectively. Using the experimentally derived density of ρ1 = 1.56 g/cm(3) for a commercially available β-CuPc (nanoparticles of ∼90 nm hydrodynamic diameter), A11 = 13.52 × 10(-20) J is found. Its corresponding effective Hamaker constant in water (A121) is calculated to be 3.07 × 10(-20) J. All computed A11 values for CuPc are noted to be higher than those reported previously.

Mechanism of thermal electron attachment to NO/sub 2/

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

Shimamori, H.; Hotta, H.

1986-03-15

The mechanism of thermal electron attachment to NO/sub 2/ has been reexamined by observing the dependence of the attachment rates on the nature and the pressure of the environmental gases. Measurements for mixtures of NO/sub 2/ with rare gases, H/sub 2/, D/sub 2/, N/sub 2/, CO/sub 2/, and n-C/sub 4/H/sub 10/ all showed two-body pressure dependence of the attachment rates at buffer-gas pressures of about 10 to 100 Torr. They gave the same two-body rate constant of (1.13 +- 0.07) x 10/sup -10/ cm/sup 3/ molecule/sup -1/ s/sup -1/. The latter result disagrees with the data reported by Mahan andmore » Walker in 1967. The present results indicate that the collisional electron detachment process introduced previously to interpret the effect of the nature of environmental gases should be negligible. We have also observed the decrease of the two-body rate constants at pressures below about 10 Torr for all the mixtures studied. This strongly suggests that the attachment mechanism is an ordinary two-step three-body process. The three-body rate constants then obtained are mostly of the orders of 10/sup -27/ cm/sup 6/ molecule/sup -2/ s/sup -1/ and do not differ much with nature of the third bodies. An autoionization lifetime of 1 x 10/sup -8/ s has been estimated for the transient-negative ion of NO/sub 2/. It has been found that even room light could cause appreciable decrease of the rate constants, probably through decomposition of NO/sub 2/ molecules. The discrepancy between the present results and the previous ones may be due to such an effect.« less

Absolute protein-protein association rate constants from flexible, coarse-grained Brownian dynamics simulations: the role of intermolecular hydrodynamic interactions in barnase-barstar association.

PubMed

Frembgen-Kesner, Tamara; Elcock, Adrian H

2010-11-03

Theory and computation have long been used to rationalize the experimental association rate constants of protein-protein complexes, and Brownian dynamics (BD) simulations, in particular, have been successful in reproducing the relative rate constants of wild-type and mutant protein pairs. Missing from previous BD studies of association kinetics, however, has been the description of hydrodynamic interactions (HIs) between, and within, the diffusing proteins. Here we address this issue by rigorously including HIs in BD simulations of the barnase-barstar association reaction. We first show that even very simplified representations of the proteins--involving approximately one pseudoatom for every three residues in the protein--can provide excellent reproduction of the absolute association rate constants of wild-type and mutant protein pairs. We then show that simulations that include intermolecular HIs also produce excellent estimates of association rate constants, but, for a given reaction criterion, yield values that are decreased by ∼35-80% relative to those obtained in the absence of intermolecular HIs. The neglect of intermolecular HIs in previous BD simulation studies, therefore, is likely to have contributed to the somewhat overestimated absolute rate constants previously obtained. Consequently, intermolecular HIs could be an important component to include in accurate modeling of the kinetics of macromolecular association events. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

In vitro and in vivo comparisons of constant resistance AC iontophoresis and DC iontophoresis.

PubMed

Li, S Kevin; Higuchi, William I; Zhu, Honggang; Kern, Steven E; Miller, David J; Hastings, Matthew S

2003-09-04

A previous in vitro constant electrical resistance alternating current (AC) iontophoresis study with human epidermal membrane (HEM) and a model neutral permeant has shown less inter- and intra-sample variability in iontophoretic transport relative to conventional constant direct current (DC) iontophoresis. The objectives of the present study were to address the following questions. (1) Can the skin electrical resistance be maintained at a constant level by AC in humans in vivo? (2) Are the in vitro data with HEM representative of those in vivo? (3) Does constant skin resistance AC iontophoresis have less inter- and intra-sample variability than conventional constant current DC iontophoresis in vivo? (4) What are the electrical and the barrier properties of skin during iontophoresis in vivo? In the present study, in vitro HEM experiments were carried out with the constant resistance AC and the conventional constant current DC methods using mannitol and glucose as the neutral model permeants. In vivo human experiments were performed using glucose as the permeant with a constant skin resistance AC only protocol and two conventional constant current DC methods (continuous constant current DC and constant current DC with its polarity alternated every 10 min with a 3:7 on:off duty cycle). Constant current DC iontophoresis was conducted with commercial constant current DC devices, and constant resistance AC iontophoresis was carried out by reducing and maintaining the skin resistance at a constant target value with AC supplied from a function generator. This study shows that (1) skin electrical resistance can be maintained at a constant level during AC iontophoresis in vivo; (2) HEM in vitro and human skin in vivo demonstrate similar electrical and barrier properties, and these properties are consistent with our previous findings; (3) there is general qualitative and semi-quantitative agreement between the HEM data in vitro and human skin data in vivo; and (4) constant skin resistance AC iontophoresis generally provides less inter- and intra-subject variability than conventional constant current DC.

Metamaterial Behavior of Polymer Nanocomposites Based on Polypropylene/Multi-Walled Carbon Nanotubes Fabricated by Means of Ultrasound-Assisted Extrusion

PubMed Central

Pérez-Medina, Juan C.; Waldo-Mendoza, Miguel A.; Cruz-Delgado, Víctor J.; Quiñones-Jurado, Zoe V.; González-Morones, Pablo; Ziolo, Ronald F.; Martínez-Colunga, Juan G.; Soriano-Corral, Florentino; Avila-Orta, Carlos A.

2016-01-01

Metamaterial behavior of polymer nanocomposites (NCs) based on isotactic polypropylene (iPP) and multi-walled carbon nanotubes (MWCNTs) was investigated based on the observation of a negative dielectric constant (ε′). It is demonstrated that as the dielectric constant switches from negative to positive, the plasma frequency (ωp) depends strongly on the ultrasound-assisted fabrication method, as well as on the melt flow index of the iPP. NCs were fabricated using ultrasound-assisted extrusion methods with 10 wt % loadings of MWCNTs in iPPs with different melt flow indices (MFI). AC electrical conductivity (σ(AC)) as a function of frequency was determined to complement the electrical classification of the NCs, which were previously designated as insulating (I), static-dissipative (SD), and conductive (C) materials. It was found that the SD and C materials can also be classified as metamaterials (M). This type of behavior emerges from the negative dielectric constant observed at low frequencies although, at certain frequencies, the dielectric constant becomes positive. Our method of fabrication allows for the preparation of metamaterials with tunable ωp. iPP pure samples show only positive dielectric constants. Electrical conductivity increases in all cases with the addition of MWCNTs with the largest increases observed for samples with the highest MFI. A relationship between MFI and the fabrication method, with respect to electrical properties, is reported. PMID:28774042

Insights from Smart Meters: Ramp-Up, Dependability, and Short-Term Persistence of Savings from Home Energy Reports

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

Todd, A.; Perry, M.; Smith, B.

2015-04-01

Smart meters, smart thermostats, and other new technologies provide previously unavailable high-frequency and location-specific energy usage data. Many utilities are now able to capture real-time, customer-specific hourly interval usage data for a large proportion of their residential and small commercial customers. These vast, constantly growing streams of rich data (or big data) have the potential to provide novel insights into key policy questions about how people make energy decisions.

Electrical properties of lunar soil dependence on frequency, temperature and moisture.

NASA Technical Reports Server (NTRS)

Strangway, D. W.; Chapman, W. B.; Olhoeft, G. R.; Carnes, J.

1972-01-01

It was found that the dielectric constant and loss tangent of lunar soil samples in the range from 100 Hz to 1 MHz are not strongly dependent on frequency provided care is taken to avoid exposure of the sample to atmospheric air containing moisture. The loss tangent value obtained is lower by nearly a factor 10 than any previously reported value. The measurement data imply that the surface layers of the moon are probably extremely transparent to radiowaves.

The Effects of Channel Curvature and Protrusion Height on Nucleate Boiling and the Critical Heat Flux of a Simulated Electronic Chip

DTIC Science & Technology

1994-05-01

parameters and geometry factor. 57 3.2 Laminar sublayer and buffer layer thicknesses for geometry of Mudawar and Maddox.ŝ 68 3.3 Correlation constants...transfer from simulated electronic chip heat sources that are flush with the flow channel wall. Mudawar and Maddox2" have studied enhanced surfaces...bias error was not estimated; however, the percentage of heat loss measured compares with that previously reported by Mudawar and Maddox19 for a

Mach-Zehnder Interferometer Refractive Index Sensor Based on a Plasmonic Channel Waveguide

PubMed Central

Lee, Da Eun; Lee, Young Jin; Shin, Eunso; Kwon, Soon-Hong

2017-01-01

A Mach-Zehnder interferometer based on a plasmonic channel waveguide is proposed for refractive index sensing. The structure, with a small physical footprint of 20 × 120 μm2, achieved a high figure of merit of 294. The cut-off frequency behaviour in the plasmonic channel waveguide resulted in a flat dispersion curve, which induces a 1.8 times larger change of the propagation constant for the given refractive index change compared with previously reported results. PMID:29120381

Absolute rate constant for the O plus NO chemiluminescence in the near infrared

NASA Technical Reports Server (NTRS)

Golde, M. F.; Roche, A. E.; Kaufman, F.

1973-01-01

Infrared chemiluminescence from the process O + NO (+M) NO2 + hv (+M) has been studied between 1.3 and 4.1 micrometer. The wavelength dependence of the continuum between 1.3 and 3.3 micrometer is in fair agreement with previous studies and the measured radiative rate constant at 1.51 micrometer establishes the NO-O glow in this spectral range as a secondary emission standard. Comparison with previous studies of the visible region of the glow implies that the overall radiative rate constant lies in the range (9.4 to 11.2) x 10 to the minus 17 power cu cm sec/1. In the region 3.3 to 4.1 micrometer, the previously observed broad band, peaking at 3.7 micrometer, shows a complex kinetic dependence on O and M.

Oxidative elimination of cyanotoxins: comparison of ozone, chlorine, chlorine dioxide and permanganate.

PubMed

Rodríguez, Eva; Onstad, Gretchen D; Kull, Tomas P J; Metcalf, James S; Acero, Juan L; von Gunten, Urs

2007-08-01

As the World Health Organization (WHO) progresses with provisional Drinking Water Guidelines of 1 microg/L for microcystin-LR and a proposed Guideline of 1 microg/L for cylindrospermopsin, efficient treatment strategies are needed to prevent cyanotoxins such as these from reaching consumers. A kinetic database has been compiled for the oxidative treatment of three cyanotoxins: microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-a (ANTX) with ozone, chlorine, chlorine dioxide and permanganate. This kinetic database contains rate constants not previously reported and determined in the present work (e.g. for permanganate oxidation of ANTX and chlorine dioxide oxidation of CYN and ANTX), together with previously published rate constants for the remaining oxidation processes. Second-order rate constants measured in pure aqueous solutions of these toxins could be used in a kinetic model to predict the toxin oxidation efficiency of ozone, chlorine, chlorine dioxide and permanganate when applied to natural waters. Oxidants were applied to water from a eutrophic Swiss lake (Lake Greifensee) in static-dose testing and dynamic time-resolved experiments to confirm predictions from the kinetic database, and to investigate the effects of a natural matrix on toxin oxidation and by-product formation. Overall, permanganate can effectively oxidize ANTX and MC-LR, while chlorine will oxidize CYN and MC-LR and ozone is capable of oxidizing all three toxins with the highest rate. The formation of trihalomethanes (THMs) in the treated water may be a restriction to the application of sufficiently high-chlorine doses.

Quenching of I(2P 1/2) by O 3 and O( 3P)

NASA Astrophysics Data System (ADS)

Azyazov, V. N.; Antonov, I. O.; Ruffner, S.; Heaven, M. C.

2006-02-01

Oxygen-iodine lasers that utilize electrical or microwave discharges to produce singlet oxygen are currently being developed. The discharge generators differ from conventional chemical singlet oxygen generators in that they produce significant amounts of atomic oxygen. Post-discharge chemistry includes channels that lead to the formation of ozone. Consequently, removal of I(2P 1/2) by O atoms and O 3 may impact the efficiency of discharge driven iodine lasers. In the present study we have measured the rate constants for quenching of I(2P 1/2) by O( 3P) atoms and O 3 using pulsed laser photolysis techniques. The rate constant for quenching by O 3, 1.8x10 -12 cm 3 s -1, was found to be a factor of five smaller than the literature value. The rate constant for quenching by O( 3P) was 1.2x10 -11 cm 3 s -1. This was six times larger than a previously reported upper bound, but consistent with estimates obtained by modeling the kinetics of discharge-driven laser systems.

A laser flash photolysis-resonance fluorescence kinetics study of the reaction Cl/2P/ + CH4 yields CH3 + HCl

NASA Technical Reports Server (NTRS)

Ravishankara, A. R.; Wine, P. H.

1980-01-01

The technique of laser flash photolysis-resonance fluorescence is employed to study the kinetics of the reaction Cl(2P) + CH4 yields CH3 + HCl over the temperature range 221-375 K. At temperatures less than or equal to 241 K the apparent bimolecular rate constant is found to be dependent upon the identity of the chemically inert gases in the reaction mixture. For Cl2/CH4/He reaction mixtures (total pressure = 50 torr) different bimolecular rate constants are measured at low and high methane concentrations. For Cl2/CH4/CCl/He and Cl2/CH4/Ar reaction mixtures, the bimolecular rate constant is independent of methane concentration, being approximately equal to the rate constant measured at low methane concentrations for Cl2/CH4/He mixtures. These rate constants are in good agreement with previous results obtained using the discharge flow-resonance fluorescence and competitive chlorination techniques. At 298 K the measured bimolecular rate constant is independent of the identity of the chemically inert gases in the reaction mixture and in good agreement with all previous investigations. The low-temperature results obtained in this investigation and all previous investigations can be rationalized in terms of a model which assumes that the Cl(2P 1/2) state reacts with CH4 much faster than the Cl(2P 3/2) state. Extrapolation of this model to higher temperatures, however, is not straightforward.

Extracellular DNA Impedes the Transport of Vancomycin in Staphylococcus epidermidis Biofilms Preexposed to Subinhibitory Concentrations of Vancomycin

PubMed Central

Tseng, Boo Shan; Howlin, Robert P.; Deacon, Jill; Wharton, Julian A.; Thurner, Philipp J.; Gilmore, Brendan F.; Parsek, Matthew R.; Stoodley, Paul

2014-01-01

Staphylococcus epidermidis biofilm formation is responsible for the persistence of orthopedic implant infections. Previous studies have shown that exposure of S. epidermidis biofilms to sub-MICs of antibiotics induced an increased level of biofilm persistence. BODIPY FL-vancomycin (a fluorescent vancomycin conjugate) and confocal microscopy were used to show that the penetration of vancomycin through sub-MIC-vancomycin-treated S. epidermidis biofilms was impeded compared to that of control, untreated biofilms. Further experiments showed an increase in the extracellular DNA (eDNA) concentration in biofilms preexposed to sub-MIC vancomycin, suggesting a potential role for eDNA in the hindrance of vancomycin activity. Exogenously added, S. epidermidis DNA increased the planktonic vancomycin MIC and protected biofilm cells from lethal vancomycin concentrations. Finally, isothermal titration calorimetry (ITC) revealed that the binding constant of DNA and vancomycin was 100-fold higher than the previously reported binding constant of vancomycin and its intended cellular d-Ala-d-Ala peptide target. This study provides an explanation of the eDNA-based mechanism of antibiotic tolerance in sub-MIC-vancomycin-treated S. epidermidis biofilms, which might be an important factor for the persistence of biofilm infections. PMID:25267673

The Role of Binding Site on the Mechanical Unfolding Mechanism of Ubiquitin

NASA Astrophysics Data System (ADS)

Cao, Penghui; Yoon, Gwonchan; Tao, Weiwei; Eom, Kilho; Park, Harold S.

2015-03-01

We apply novel atomistic simulations based on potential energy surface exploration to investigate the constant force-induced unfolding of ubiquitin. At the experimentally-studied force clamping level of 100 pN, we find a new unfolding mechanism starting with the detachment between β5 and β3 involving the binding site of ubiquitin, the Ile44 residue. This new unfolding pathway leads to the discovery of new intermediate configurations, which correspond to the end-to-end extensions previously seen experimentally. More importantly, it demonstrates the novel finding that the binding site of ubiquitin can be responsible not only for its biological functions, but also its unfolding dynamics. We also report in contrast to previous single molecule constant force experiments that when the clamping force becomes smaller than about 300 pN, the number of intermediate configurations increases dramatically, where almost all unfolding events at 100 pN involve an intermediate configuration. By directly calculating the life times of the intermediate configurations from the height of the barriers that were crossed on the potential energy surface, we demonstrate that these intermediate states were likely not observed experimentally due to their lifetimes typically being about two orders of magnitude smaller than the experimental temporal resolution.

Rhythms of glycerophospholipid synthesis in retinal inner nuclear layer cells.

PubMed

Garbarino-Pico, Eduardo; Valdez, Diego J; Contín, María A; Pasquaré, Susana J; Castagnet, Paula I; Giusto, Norma M; Caputto, Beatriz L; Guido, Mario E

2005-09-01

The present study demonstrates that the biosynthesis of phospholipids in the inner nuclear layer cells of the chicken retina displays daily rhythms under constant illumination conditions. The vertebrate retina contains circadian oscillators and photoreceptors (PRCs) that temporally regulate its own physiology and synchronize the whole organism to the daily environmental changes. We have previously reported that chicken photoreceptors and retinal ganglion cells (RGCs) present significant daily variations in their phospholipid biosynthesis under constant illumination conditions. Herein, we demonstrate that cell preparations highly enriched in inner nuclear layer cells also exhibit a circadian-regulated phospholipid labeling after the in vivo administration of [(32)P]phosphate or [(3)H]glycerol both in animals maintained under constant darkness or light for at least 48h. In constant darkness, there was a significant incorporation of both precursors into phospholipids with the highest levels of labeling around midday and dusk. In constant light, the labeling of (32)P-phospholipids was also significantly higher during the day and early night whereas the incorporation of [(3)H]glycerol into phospholipids, that indicates de novo biosynthesis, was greater during the day but probably reflecting a higher precursor availability at those phases. We also measured the in vitro activity of phosphatidate phosphohydrolase and diacylglycerol lipase in preparations obtained from the dark condition. The two enzymes exhibited the highest activity levels late in the day. When we assessed the in vitro incorporation of [(14)C]oleate into different lysophospholipids from samples collected at different phases in constant darkness, reaction catalyzed by lysophospholipid acyltransferases II, labeling showed a complex pattern of daily activity. Taken together, these results demonstrate that the biosynthesis of phospholipids in cells of the chicken retinal inner nuclear layer exhibits a daily rhythmicity under constant illumination conditions, which is controlled by a circadian clock.

Evolution of robust circadian clocks in Drosophila melanogaster populations reared in constant dark for over 330 generations

NASA Astrophysics Data System (ADS)

Shindey, Radhika; Varma, Vishwanath; Nikhil, K. L.; Sharma, Vijay Kumar

2016-10-01

Robustness is considered to be an important feature of biological systems which may evolve when the functionality of a trait is associated with higher fitness across multiple environmental conditions. Thus, the ability to maintain stable biological phenotypes across environments is thought to be of adaptive value. Previously, we have reported higher intrinsic activity levels (activity levels of free-running rhythm in constant darkness) and power of rhythm (as assessed by amplitude of the periodogram) in Drosophila melanogaster populations (stocks) reared in constant darkness (DD stocks) as compared to those reared in constant light (LL stocks) and 12:12-h light-dark cycles (LD stocks) for over 19 years (˜330 generations). In the current study, we intended to examine whether the enhanced levels of activity observed in DD stocks persist under various environments such as photoperiods, ambient temperatures, non-24-h light-dark (LD) cycles, and semi-natural conditions (SN). We found that DD stocks largely retain their phenotype of enhanced activity levels across most of the above-mentioned environments suggesting the evolution of robust circadian clocks in DD stocks. Furthermore, we compared the peak activity levels of the three stocks across different environmental conditions relative to their peaks in constant darkness and found that the change in peak activity levels upon entrainment was not significantly different across the three stocks for any of the examined environmental conditions. This suggests that the enhancement of activity levels in DD stocks is not due to differential sensitivity to environment. Thus, these results suggest that rearing in constant darkness (DD) leads to evolution of robust circadian clocks suggesting a possible adaptive value of possessing such rhythms under constant dark environments.

Evolution of robust circadian clocks in Drosophila melanogaster populations reared in constant dark for over 330 generations.

PubMed

Shindey, Radhika; Varma, Vishwanath; Nikhil, K L; Sharma, Vijay Kumar

2016-10-01

Robustness is considered to be an important feature of biological systems which may evolve when the functionality of a trait is associated with higher fitness across multiple environmental conditions. Thus, the ability to maintain stable biological phenotypes across environments is thought to be of adaptive value. Previously, we have reported higher intrinsic activity levels (activity levels of free-running rhythm in constant darkness) and power of rhythm (as assessed by amplitude of the periodogram) in Drosophila melanogaster populations (stocks) reared in constant darkness (DD stocks) as compared to those reared in constant light (LL stocks) and 12:12-h light-dark cycles (LD stocks) for over 19 years (∼330 generations). In the current study, we intended to examine whether the enhanced levels of activity observed in DD stocks persist under various environments such as photoperiods, ambient temperatures, non-24-h light-dark (LD) cycles, and semi-natural conditions (SN). We found that DD stocks largely retain their phenotype of enhanced activity levels across most of the above-mentioned environments suggesting the evolution of robust circadian clocks in DD stocks. Furthermore, we compared the peak activity levels of the three stocks across different environmental conditions relative to their peaks in constant darkness and found that the change in peak activity levels upon entrainment was not significantly different across the three stocks for any of the examined environmental conditions. This suggests that the enhancement of activity levels in DD stocks is not due to differential sensitivity to environment. Thus, these results suggest that rearing in constant darkness (DD) leads to evolution of robust circadian clocks suggesting a possible adaptive value of possessing such rhythms under constant dark environments.

Infrared optical constants, dielectric constants, molar polarizabilities, transition moments, dipole moment derivatives and Raman spectrum of liquid cyclohexane

NASA Astrophysics Data System (ADS)

Keefe, C. Dale; Pickup, Janet E.

2009-06-01

Previous studies have been done in this laboratory focusing on the optical properties of several liquid aromatic and aliphatic hydrocarbons in the infrared. The current study reports the infrared and absorption Raman spectra of liquid cyclohexane. Infrared spectra were recorded at 25 °C over a wavenumber range of 7400-490 cm -1. Infrared measurements were taken using transmission cells with pathlengths ranging from 3 to 5000 μm. Raman spectra were recorded between 3700 and 100 cm -1 at 25 °C using a 180° reflection geometry. Ab initio calculations of the vibrational wavenumbers at the B3LYP/6311G level of theory were performed and used to help assign the observed IR and Raman spectra. Extensive assignments of the fundamentals and binary combinations observed in the infrared imaginary molar polarizability spectrum are reported. The imaginary molar polarizability spectrum was curve fitted to separate the intensity from the various transitions and used to determine the transition moments and magnitudes of the derivatives of the dipole moment with respect to the normal coordinates for the fundamentals.

The analytical representation of viscoelastic material properties using optimization techniques

NASA Technical Reports Server (NTRS)

Hill, S. A.

1993-01-01

This report presents a technique to model viscoelastic material properties with a function of the form of the Prony series. Generally, the method employed to determine the function constants requires assuming values for the exponential constants of the function and then resolving the remaining constants through linear least-squares techniques. The technique presented here allows all the constants to be analytically determined through optimization techniques. This technique is employed in a computer program named PRONY and makes use of commercially available optimization tool developed by VMA Engineering, Inc. The PRONY program was utilized to compare the technique against previously determined models for solid rocket motor TP-H1148 propellant and V747-75 Viton fluoroelastomer. In both cases, the optimization technique generated functions that modeled the test data with at least an order of magnitude better correlation. This technique has demonstrated the capability to use small or large data sets and to use data sets that have uniformly or nonuniformly spaced data pairs. The reduction of experimental data to accurate mathematical models is a vital part of most scientific and engineering research. This technique of regression through optimization can be applied to other mathematical models that are difficult to fit to experimental data through traditional regression techniques.

High-resolution far-infrared synchrotron FTIR spectrum of the ν12 band of formamide-d1 (DCONH2)

NASA Astrophysics Data System (ADS)

Tan, T. L.; Wu, Q. Y.; Ng, L. L.; Appadoo, Dominique R. T.; McNaughton, Don

2018-05-01

The spectrum of the ν12 band of formamide-d1 (DCONH2) was recorded using a synchrotron Fourier transform infrared (FTIR) spectrometer coupled to the Australian Synchrotron THz/Far-IR beamline, with an unapodized resolution of 0.00096 cm-1 in the 350-210 cm-1 region. For the first time, rovibrational constants up to five quartic and two sextic terms were derived for the v12 = 1 state through the fitting of a total of 2072 far-infrared transitions using Watson's A-reduced Hamiltonian in the Ir representation with a root-mean-square (rms) deviation of 0.000073 cm-1. The band centre of the ν12 band of DCONH2 was found to be 289.3327553(47) cm-1 although the experimental uncertainty was limited to ±0.0002 cm-1. Ground state rovibrational constants of DCONH2 up to five quartic and two sextic constants were derived from a fit of 847 ground state combination differences (GSCDs) obtained from the infrared transitions of the ν12 band, together with 6 previously reported microwave transitions, with a rms deviation of 0.000108 cm-1. The ground state rotational constants (A, B, and C) of DCONH2 were improved while the ground state centrifugal distortion constants were accurately obtained for the first time. The uncertainty of the measured infrared lines was estimated to be ±0.0002 cm-1. From the ground state rotational constants, the inertial defect of DCONH2 was calculated to be 0.0169412(11) uÅ2.

Development, refinement, and testing of a short term solar flare prediction algorithm

NASA Technical Reports Server (NTRS)

Smith, Jesse B., Jr.

1993-01-01

During the period included in this report, the expenditure of time and effort, and progress toward performance of the tasks and accomplishing the goals set forth in the two year research grant proposal, consisted primarily of calibration and analysis of selected data sets. The heliographic limits of 30 degrees from central meridian were continued. As previously reported, all analyses are interactive and are performed by the Principal Investigator. It should also be noted that the analysis time involved by the Principal Investigator during this reporting period was limited, partially due to illness and partially resulting from other uncontrollable factors. The calibration technique (as developed by MSFC solar scientists), incorporates sets of constants which vary according to the wave length of the observation data set. One input constant is then varied interactively to correct for observing conditions, etc., to result in a maximum magnetic field strength (in the calibrated data), based on a separate analysis. There is some insecurity in the methodology and the selection of variables to yield the most self-consistent results for variable maximum field strengths and for variable observing/atmospheric conditions. Several data sets were analyzed using differing constant sets, and separate analyses to differing maximum field strength - toward standardizing methodology and technique for the most self-consistent results for the large number of cases. It may be necessary to recalibrate some of the analyses, but the sc analyses are retained on the optical disks and can still be used with recalibration where necessary. Only the extracted parameters will be changed.

Equilibrium Conformations of Concentric-tube Continuum Robots

PubMed Central

Rucker, D. Caleb; Webster, Robert J.; Chirikjian, Gregory S.; Cowan, Noah J.

2013-01-01

Robots consisting of several concentric, preshaped, elastic tubes can work dexterously in narrow, constrained, and/or winding spaces, as are commonly found in minimally invasive surgery. Previous models of these “active cannulas” assume piecewise constant precurvature of component tubes and neglect torsion in curved sections of the device. In this paper we develop a new coordinate-free energy formulation that accounts for general preshaping of an arbitrary number of component tubes, and which explicitly includes both bending and torsion throughout the device. We show that previously reported models are special cases of our formulation, and then explore in detail the implications of torsional flexibility for the special case of two tubes. Experiments demonstrate that this framework is more descriptive of physical prototype behavior than previous models; it reduces model prediction error by 82% over the calibrated bending-only model, and 17% over the calibrated transmissional torsion model in a set of experiments. PMID:25125773

Gender differences in self-reported anxiety, depression, and somatization among ecstasy/MDMA polydrug users, alcohol/tobacco users, and nondrug users.

PubMed

Milani, Raffaella M; Parrott, Andy C; Turner, John J D; Fox, Helen C

2004-07-01

Previous research has found gender differences in both psychological and physiological responses to drugs. The present investigation explores gender variability in patterns of drug use in relation to self-reported depression, anxiety, and somatization. The current study confirms that heavy illegal drug users are represented by a preponderance of males than females. However, within each drug group category, females generally reported higher psychopathology scores than males. This was significant for all three subscales in the alcohol/tobacco group, for depression scores in the alcohol/tobacco, cannabis/alcohol, and light Ecstasy users group, and for depression scores for the alcohol group. Interestingly, in the male sample, drug users reported higher symptom ratings than nondrug users, whereas women's scores remained constant across drug groups. Copyright 2004 Elsevier Ltd.

Tissue vitamin concentrations are maintained constant by changing the urinary excretion rate of vitamins in rats' restricted food intake.

PubMed

Shibata, Katsumi; Fukuwatari, Tsutomu

2014-01-01

We previously reported that mild food restriction induces a reduction in tryptophan-nicotinamide conversion, which helps to explain why death secondary to pellagra is pandemic during the hungry season. In this study, we investigated the levels of B-group vitamins in the liver, kidney, blood, and urine in rats that underwent gradual restriction of food intake (80, 60, 40, and 20% restriction vs. ad libitum food intake). No significant differences in the B-group vitamin concentrations (mol/g tissue) in the liver and kidney were observed at any level of food restriction. However, the urine excretion rates exhibited some characteristic phenomena that differed by vitamin. These results show that the tissue concentrations of B-group vitamins were kept constant by changing the urinary elimination rates of vitamins under various levels of food restriction. Only vitamin B12 was the only (exception).

A Constant Pressure Bomb

NASA Technical Reports Server (NTRS)

Stevens, F W

1924-01-01

This report describes a new optical method of unusual simplicity and of good accuracy suitable to study the kinetics of gaseous reactions. The device is the complement of the spherical bomb of constant volume, and extends the applicability of the relationship, pv=rt for gaseous equilibrium conditions, to the use of both factors p and v. The method substitutes for the mechanical complications of a manometer placed at some distance from the seat of reaction the possibility of allowing the radiant effects of reaction to record themselves directly upon a sensitive film. It is possible the device may be of use in the study of the photoelectric effects of radiation. The method makes possible a greater precision in the measurement of normal flame velocities than was previously possible. An approximate analysis shows that the increase of pressure and density ahead of the flame is negligible until the velocity of the flame approaches that of sound.

Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

PubMed

Zou, Wenli; Liu, Wenjian

2006-04-21

The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

An experimental study of opposed flow diffusion flame extinction over a thin fuel in microgravity. M.S. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Ferkul, Paul V.

1989-01-01

The flame spread and flame extinction characteristics of a thin fuel burning in a low-speed forced convective environment in microgravity were examined. The flame spread rate was observed to decrease both with decreasing ambient oxygen concentration as well as decreasing free stream velocity. A new mode of flame extinction was observed, caused by either of two means: keeping the free stream velocity constant and decreasing the oxygen concentration, or keeping the oxygen concentration constant and decreasing the free stream velocity. This extinction is called quenching extinction. By combining this data together with a previous microgravity quiescent flame study and normal-gravity blowoff extinction data, a flammability map was constructed with molar percentage oxygen and characteristic relative velocity as coordinates. The Damkohler number is not sufficient to predict flame spread and extinction in the near quench limit region.

ESR spectrum of Cr(V) with 2,3-dioxynaphthalene in a liquid crystal

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

Novosadov, N.A.; Mukhtarov, A.S.; Usmanov, Z.I.

1987-01-01

Research has previously been reported on the complex formed by Cr(V) with 2,3-dioxynaphthalene (I) in solution in DMFA. An open question remaining is the mutual orientation of the molecular symmetry axes and the magnetic ones. The authors give results on the complex formed by Cr(V) with I obtained by ESR in 4-methoxy-benzylidene-n-4'-butylaniline (MBBA). The ESR spectrum of Cr(V) with I in the nematic phase of MBBA is a strong line due to /sup 52/Cr with g = 1.978 and four weak lines due to /sup 53/Cr at the natural content with HFI constant a* = 11.8 x 10/sup -4/ T;more » when the MBBA is converted to the isotropic phase, the observed HFI constant from /sup 53/Cr increases to 18 x 10/sup -4/ T, while the g factor is unaltered.« less

Multiple Mechanisms of Zinc-Mediated Inhibition for the Apoptotic Caspases-3, -6, -7, and -8.

PubMed

Eron, Scott J; MacPherson, Derek J; Dagbay, Kevin B; Hardy, Jeanne A

2018-05-18

Zinc is emerging as a widely used and important biological regulatory signal. Cellular zinc levels are tightly regulated by a complex array of zinc importers and exporters to control processes such as apoptotic cell death. While caspase inhibition by zinc has been reported previously, the reported inhibition constants were too weak to suggest a critical biological role for zinc-mediated inhibition. In this work, we have adopted a method of assessing available zinc. This allowed assessment of accurate inhibition constants for apoptotic caspases, caspase-3, -6, -7, and -8. Each of these caspases are inhibited by zinc at intracellular levels but with widely differing inhibition constants and different zinc binding stoichiometries. Caspase-3, -6, and -8 appear to be constitutively inhibited by typical zinc levels, and this inhibition must be lifted to allow activation. The inhibition constant for caspase-7 (76 nM) is much weaker than for the other apoptotic caspases (2.6-6.9 nM) suggesting that caspase-7 is not inactivated by normal zinc concentrations but can be inhibited under conditions of zinc stress. Caspase-3, -7, and -8 were found to bind three, one, and two zincs, respectively. In each of these caspases, zinc was present in the active site, in contrast to caspase-6, which binds one zinc allosterically. The most notable new mechanism to emerge from this work is for zinc-mediated inhibition of caspase-8. Zinc binds caspase-8 directly at the active site and at a second site. Zinc binding inhibits formation of the caspase-8 dimer, the activated form of the enzyme. Together these findings suggest that zinc plays a critical role in regulation of apoptosis by direct inactivation of caspases, in a manner that is unique for each caspase.

Elementary reaction profile and chemical kinetics study of [C(1D)/(3P) + SiH4] with the CCSD(T) method

NASA Astrophysics Data System (ADS)

Ranka, Karnamohit; Perera, Ajith; Bartlett, Rodney J.

2017-07-01

Carbon and silicon-based molecules are omnipresent in the fields of combustion, atmospheric, semiconductor, and astronomical chemistry, among others. This paper reports the underlying elementary reactions for the [C(1D) + SiH4] and [C(3P) + SiH4] reaction profiles, optimized geometries of the intermediates, transition states (at the CCSD(T) level), RRKM and TST rate constants, and the corresponding branching ratios. Previously unreported van der Waals complex intermediates have been found for both reactions.

Analysis of the A ∼ - X ∼ bands of the ethynyl radical near 1.48 μ m and re-evaluation of X ∼ state energies

NASA Astrophysics Data System (ADS)

Le, A. T.; Gross, Eisen C.; Hall, Gregory E.; Sears, Trevor J.

2018-07-01

We report the observation and analysis of spectra in part of the near-infrared spectrum of C2H, originating in rotational levels in the ground and lowest two excited bending vibrational levels of the ground X ˜ 2Σ+ state. In the analysis, we have combined present and previously reported high resolution spectroscopic data for the lower levels involved in the transitions to determine significantly improved molecular constants to describe the fine and hyperfine split rotational levels of the radical in the zero point, v2 = 1 and the 2Σ+ component of v2 = 2 . Two of the upper state vibronic levels involved had not been observed previously. The data and analysis indicate the electronic wavefunction character changes with bending vibrational excitation in the ground state and provide avenues for future measurements of reactivity of the radical as a function of vibrational excitation.

Analysis of the $$\\tilde{A}$$ - $$\\tilde{X}$$ bands of the Ethynyl Radical near 1.48 μ-m and Re-evaluation of ~X State Energies

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

Le, A T.; Gross, Eisen C.; Hall, Gregory E.

Here, we report the observation and analysis of spectra in part of the near-infrared spectrum of C 2H, originating in rotational levels in the ground and lowest two excited bending vibrational levels of the groundmore » $$\\tilde{X}$$ 2Σ+ state. In the analysis, we have combined present and previously reported high resolution spectroscopic data for the lower levels involved in the transitions to determine significantly improved molecular constants to describe the fine and hyperfine split rotational levels of the radical in the zero point, v 2 = 1 and the 2Σ+ component of v 2 = 2. Two of the upper state vibronic levels involved had not been observed previously. The data and analysis indicate the electronic wavefunction character changes with bending vibrational excitation in the ground state and provide avenues for future measurements of reactivity of the radical as a function of vibrational excitation.« less

Analysis of the $$\\tilde{A}$$ - $$\\tilde{X}$$ bands of the Ethynyl Radical near 1.48 μ-m and Re-evaluation of ~X State Energies

DOE PAGES

Le, A T.; Gross, Eisen C.; Hall, Gregory E.; ...

2018-05-15

Here, we report the observation and analysis of spectra in part of the near-infrared spectrum of C 2H, originating in rotational levels in the ground and lowest two excited bending vibrational levels of the groundmore » $$\\tilde{X}$$ 2Σ+ state. In the analysis, we have combined present and previously reported high resolution spectroscopic data for the lower levels involved in the transitions to determine significantly improved molecular constants to describe the fine and hyperfine split rotational levels of the radical in the zero point, v 2 = 1 and the 2Σ+ component of v 2 = 2. Two of the upper state vibronic levels involved had not been observed previously. The data and analysis indicate the electronic wavefunction character changes with bending vibrational excitation in the ground state and provide avenues for future measurements of reactivity of the radical as a function of vibrational excitation.« less

Enzymatic Kinetic Isotope Effects from First-Principles Path Sampling Calculations.

PubMed

Varga, Matthew J; Schwartz, Steven D

2016-04-12

In this study, we develop and test a method to determine the rate of particle transfer and kinetic isotope effects in enzymatic reactions, specifically yeast alcohol dehydrogenase (YADH), from first-principles. Transition path sampling (TPS) and normal mode centroid dynamics (CMD) are used to simulate these enzymatic reactions without knowledge of their reaction coordinates and with the inclusion of quantum effects, such as zero-point energy and tunneling, on the transferring particle. Though previous studies have used TPS to calculate reaction rate constants in various model and real systems, it has not been applied to a system as large as YADH. The calculated primary H/D kinetic isotope effect agrees with previously reported experimental results, within experimental error. The kinetic isotope effects calculated with this method correspond to the kinetic isotope effect of the transfer event itself. The results reported here show that the kinetic isotope effects calculated from first-principles, purely for barrier passage, can be used to predict experimental kinetic isotope effects in enzymatic systems.

ELEMENT MASSES IN THE CRAB NEBULA

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

Sibley, Adam R.; Katz, Andrea M.; Satterfield, Timothy J.

Using our previously published element abundance or mass-fraction distributions in the Crab Nebula, we derived actual mass distributions and estimates for overall nebular masses of hydrogen, helium, carbon, nitrogen, oxygen and sulfur. As with the previous work, computations were carried out for photoionization models involving constant hydrogen density and also constant nuclear density. In addition, employing new flux measurements for [Ni ii]  λ 7378, along with combined photoionization models and analytic computations, a nickel abundance distribution was mapped and a nebular stable nickel mass estimate was derived.

Light adaptation and dark adaptation of human rod photoreceptors measured from the a-wave of the electroretinogram

PubMed Central

Thomas, M M; Lamb, T D

1999-01-01

We recorded the a-wave of the human electroretinogram from subjects with normal vision, using a corneal electrode and ganzfeld (full-field) light stimulation. From analysis of the rising phase of rod-isolated flash responses we determined the maximum size (amax) of the a-wave, a measure of the massed circulating current of the rods, and the amplification constant (A) of transduction within the rod photoreceptors.During light adaptation by steady backgrounds the maximal response was reduced, as reported previously. amax declined approximately as I0/(I0+IB), where IB is retinal illuminance and I0 is a constant. In different subjects I0 ranged from 40 to 100 trolands, with a mean of 70 trolands, corresponding to about 600 photoisomerizations s−1 per rod. (1 troland is the retinal illuminance that results when a surface luminance of 1 cd m−2 is viewed through a pupil area of 1 mm2.) The amplification constant A decreased only slightly in the presence of steady backgrounds.Following a full bleach amax recovered along an S-shaped curve over a period of 30 min. There was no detectable response for the first 5 min, and half-maximal recovery took 13-17 min.The apparent amplification constant decreased at early times after large bleaches. However, upon correction for reduced light absorption due to loss of pigment, with regeneration of rhodopsin occurring with a time constant of 9-15 min in different subjects, it appeared that the true value of A was probably unchanged by bleaching.The recovery of amax following a bleach could be converted into recovery of equivalent background intensity, using a ‘Crawford transformation’ derived from the light adaptation results. Following bleaches ranging from 10 to > 99 %, the equivalent background intensity decayed approximately exponentially, with a time constant of about 3 min.The time taken for amax to recover to a fixed proportion of its original level increased approximately linearly (rather than logarithmically) with fractional bleach, with a slope of about 12 min per 100 % bleach. Similar behaviour has previously been seen in psychophysical dark adaptation experiments, for the dependence of the ‘second component’ of recovery on the level of bleaching. PMID:10381594

Effect of Cold Temperature on the Dielectric Constant of Soil

DTIC Science & Technology

2012-04-01

explosive device (IED) threats is ground-penetrating radar ( GPR ). Proper development of GPR technology for this application requires a unique...success or failure of GPR as a detection technique. One soil property of interest to radar engineers is the dielectric constant. Previous...results to temperatures, moisture levels, and frequencies relevant to GPR systems. 2. Dielectric Constant and the Ring-resonator Concept The two

Microscopic Modeling of Tribological Phenomena

DTIC Science & Technology

1990-02-28

37,4132 (1988). cohesive energy and lattice constant of nickel (t, -3.54 X 10- 󈧑 erg, ’This interface orientation was chosen in view ofour previous...such as lattice constants, heats of sublimation, elastic constants, vacancy-formation energies and heats of solution (47]. Following equilibration of...of the tip and 10 substrate materials to optimize their embedding energies (which are density dependent, deriving froam the tails of the atomic

D:L-AMINO Acids and the Turnover of Microbial Biomass

NASA Astrophysics Data System (ADS)

Lomstein, B. A.; Braun, S.; Mhatre, S. S.; Jørgensen, B. B.

2015-12-01

Decades of ocean drilling have demonstrated wide spread microbial life in deep sub-seafloor sediment, and surprisingly high microbial cell numbers. Despite the ubiquity of life in the deep biosphere, the large community sizes and the low energy fluxes in the vast buried ecosystem are still poorly understood. It is not know whether organisms of the deep biosphere are specifically adapted to extremely low energy fluxes or whether most of the observed cells are in a maintenance state. Recently we developed and applied a new culture independent approach - the D:L-amino acid model - to quantify the turnover times of living microbial biomass, microbial necromass and mean metabolic rates. This approach is based on the built-in molecular clock in amino acids that very slowly undergo chemical racemization until they reach an even mixture of L- and D- forms, unless microorganisms spend energy to keep them in the L-form that dominates in living organisms. The approach combines sensitive analyses of amino acids, the unique bacterial endospore marker (dipicolinic acid) with racemization dynamics of stereo-isomeric amino acids. Based on a heating experiment, we recently reported kinetic parameters for racemization of aspartic acid, glutamic acid, serine and alanine in bulk sediment from Aarhus Bay, Denmark. The obtained racemization rate constants were faster than the racemization rate constants of free amino acids, which we have previously applied in Holocene sediment from Aarhus Bay and in up to 10 mio yr old sediment from ODP Leg 201. Another important input parameter for the D:L-amino acid model is the cellular carbon content. It has recently been suggested that the cellular carbon content most likely is lower than previously thought. In recognition of these new findings, previously published data based on the D:L-amino acid model were recalculated and will be presented together with new data from an Arctic Holocene setting with constant sub-zero temperatures.

Determination of Henry`s law constants by equilibrium partitioning in a closed system using a new in situ optical absorbance method

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

Allen, J.M.; Balcavage, W.X.; Ramachandran, B.R.

Currently, a great deal of interest exists in developing quantitative descriptions of the transport behavior for organic chemical compounds in the environment. Transport between water and air is of particular significance in this regard. A new method for measurement of thermodynamic Henry`s law constants (H) is reported. In this method, the optical absorbance of a dilute aqueous solution containing an organic compound is followed with time as the compound partitions into the air above the solution in a sealed vessel. The change in optical absorbance and the vapor to liquid volume ratio of the vessel are then used to calculatemore » the value for H. The concentration of the organic compound in the aqueous and vapor phases need not be known. This method allows the approach to equilibrium to be observed in real time so that attainment of equilibrium is readily apparent. This method works particularly well for water-soluble compounds having low vapor pressures. The applicability of this method is limited to compounds that exhibit significant optical absorbance in the ultraviolet and visible regions of the electromagnetic spectrum. Values for H and their temperature dependencies measured using this new method are reported for methacrolein, methyl vinyl ketone, benzaldehyde, and acetophenone. Values for H are also reported for benzene, toluene, and ethylbenzene at 298 K. All reported H data are compared with previously reported values.« less

Effect of NiO and Light Intensity on Dielectric Constant of SiO2-B2O3-Bi2O3-Na2CO3 Glass Based on Silica Gel of Natural Sands

NASA Astrophysics Data System (ADS)

Diantoro, M.; Muniroh, Z.; Zaini, B.; Mustikasari, A. A.; Nasikhudin; Hidayat, A.; Taufiq, A.; Sunaryono; Mufti, N.

2017-05-01

The use of silica in various fields is significantly increasing. One common application is silica based functional glass which has naturally show specific dielectric, optical, and magnetic properties. Many studies have been performing to explore the influence of dopant, composition, and other processing parameters as well as employing various characterization. In the previous work, we report the use of silica from silica sands. To reduce the melting temperature, we used silica sol-gel beside the utilization of some oxides such as B2O3, Na2CO3, and Bi3O3. We also used NiO as dopant explore the glass properties. We have prepared a series of sample with the composition of 50SiO2-25B2O3-(6.5-x) Bi3O3-18.5 Na2CO3-xNiO (x = 0, 1, 2, 3 and 4 wt%). After weighting process, the composition was blended, then heated to 450 °C for 120 minutes and then raised at 950 °C for 60 minutes in the crucible. Then samples of glass separated from the crucible and in the characterization of the structure using the DTA, XRD, SEM-EDAX and FTIR and measuring dielectric constant using a capacitance meter. The increase of NiO dopant resulted in increasing the dielectric constant of glass. On the other hand, the dielectric constant gradually decreases with the increase of light intensity. One can be noted that the applied intensity give rise to the step-like decrease of the dielectric constant. Whereas, the increasing magnetic field indicate the increase of dielectric constant.

Moderate temperature-dependent surface and volume resistivity and low-frequency dielectric constant measurements of pure and multi-walled carbon nanotube (MWCNT) doped polyvinyl alcohol thin films

NASA Astrophysics Data System (ADS)

Edwards, Matthew; Guggilla, Padmaja; Reedy, Angela; Ijaz, Quratulann; Janen, Afef; Uba, Samuel; Curley, Michael

2017-08-01

Previously, we have reported measurements of temperature-dependent surface resistivity of pure and multi-walled carbon nanotube (MWNCT) doped amorphous Polyvinyl Alcohol (PVA) thin films. In the temperature range from 22 °C to 40 °C with humidity-controlled environment, we found the surface resistivity to decrease initially, but to rise steadily as the temperature continued to increase. Moreover, electric surface current density (Js) was measured on the surface of pure and MWCNT doped PVA thin films. In this regard, the surface current density and electric field relationship follow Ohm's law at low electric fields. Unlike Ohmic conduction in metals where free electrons exist, selected captive electrons are freed or provided from impurities and dopants to become conduction electrons from increased thermal vibration of constituent atoms in amorphous thin films. Additionally, a mechanism exists that seemingly decreases the surface resistivity at higher temperatures, suggesting a blocking effect for conducting electrons. Volume resistivity measurements also follow Ohm's law at low voltages (low electric fields), and they continue to decrease as temperatures increase in this temperature range, differing from surface resistivity behavior. Moreover, we report measurements of dielectric constant and dielectric loss as a function of temperature and frequency. Both the dielectric constant and dielectric loss were observed to be highest for MWCNT doped PVA compared to pure PVA and commercial paper, and with frequency and temperature for all samples.

Quenching Enhancement of the Singlet Excited State of Pheophorbide-a by DNA in the Presence of the Quinone Carboquone

PubMed Central

Díaz-Espinosa, Yisaira; Crespo-Hernández, Carlos E.; Alegría, Antonio E.; García, Carmelo; Arce, Rafael

2011-01-01

Changes in the emission fluorescence intensity of pheophorbide-a (PHEO) in the presence of carboquone (CARBOQ) were used to obtain the association constant, the number of CARBOQ molecules interacting with PHEO, and the fluorescence quantum yield of the complex. Excitation spectra of mixtures of PHEO and CARBOQ in ethanol (EtOH) show an unresolved doublet in the red-most excitation band of PHEO, indicating the formation of a loose ground-state complex. The 1:1 CARBOQ–PHEO complex shows a higher fluorescence quantum yield in EtOH (0.41 ± 0.02) than in buffer solution (0.089 ± 0.002), which is also higher than that of the PHEO monomer (0.28). Quenching of the PHEO fluorescence by DNA nucleosides and double-stranded oligonucleotides was also observed and the bimolecular quenching rate constants were determined. The quenching rate constant increase as the oxidation potential of the DNA nucleoside increases. Larger quenching constants were obtained in the presence of CARBOQ suggesting that CARBOQ enhances DNA photo-oxidation, presumably by inhibiting the back–electron-transfer reaction from the photoreduced PHEO to the oxidized base. Thus, the enhanced DNA-base photosensitized oxidation by PHEO in the presence of CARBOQ may be related to the large extent by which this quinone covalently binds to DNA, as previously reported. PMID:21138440

Strong resetting of the mammalian clock by constant light followed by constant darkness

PubMed Central

Chen, Rongmin; Seo, Dong-oh; Bell, Elijah; von Gall, Charlotte; Lee, Choogon

2008-01-01

The mammalian molecular circadian clock in the suprachiasmatic nuclei (SCN) regulates locomotor activity rhythms as well as clocks in peripheral tissues (Reppert and Weaver, 2002; Ko and Takahashi, 2006). Constant light (LL) can induce behavioral and physiological arrhythmicity, by desynchronizing clock cells in the SCN (Ohta et al., 2005). We examined how the disordered clock cells resynchronize by probing the molecular clock and measuring behavior in mice transferred from LL to constant darkness (DD). The circadian locomotor activity rhythms disrupted in LL become robustly rhythmic again from the beginning of DD, and the starting phase of the rhythm in DD is specific, not random, suggesting that the desynchronized clock cells are quickly reset in an unconventional manner by the L:D transition. By measuring mPERIOD protein rhythms, we showed that the SCN and peripheral tissue clocks quickly become rhythmic again in phase with the behavioral rhythms. We propose that this resetting mechanism may be different from conventional phase shifting, which involves light-induction of Period genes (Albrecht et al., 1997; Shearman et al., 1997; Shigeyoshi et al., 1997). Using our functional insights, we could shift the circadian phase of locomotor activity rhythms by 12 hours using a 15-hour LL treatment: essentially producing phase reversal by a single light pulse, a feat that has not been reported previously in wild-type mice and that has potential clinical utility. PMID:19005049

State memory in solution gated epitaxial graphene

NASA Astrophysics Data System (ADS)

Butko, A. V.; Butko, V. Y.; Lebedev, S. P.; Lebedev, A. A.; Davydov, V. Y.; Smirnov, A. N.; Eliseyev, I. A.; Dunaevskiy, M. S.; Kumzerov, Y. A.

2018-06-01

We studied electrical transport in transistors fabricated on a surface of high quality epitaxial graphene with density of defects as low as 5·1010 cm-2 and observed quasistatic hysteresis with a time constant in a scale of hours. This constant is in a few orders of magnitude greater than the constant previously reported in CVD graphene. The hysteresis observed here can be described as a shift of ∼+2V of the Dirac point measured during a gate voltage increase from the position of the Dirac point measured during a gate voltage decrease. This hysteresis can be characterized as a nonvolatile quasistatic state memory effect in which the state of the gated graphene is determined by its initial state prior to entering the hysteretic region. Due to this effect the difference in resistance of the gated graphene measured in the hysteretic region at the same applied voltages can be as high as 70%. The observed effect can be explained by assuming that charge carriers in graphene and oppositely charged molecular ions from the solution form quasistable interfacial complexes at the graphene interface. These complexes likely preserve the initial state by preventing charge carriers in graphene from discharging in the hysteretic region.

Entrapment of alpha1-acid glycoprotein in high-performance affinity columns for drug-protein binding studies.

PubMed

Bi, Cong; Jackson, Abby; Vargas-Badilla, John; Li, Rong; Rada, Giana; Anguizola, Jeanethe; Pfaunmiller, Erika; Hage, David S

2016-05-15

A slurry-based method was developed for the entrapment of alpha1-acid glycoprotein (AGP) for use in high-performance affinity chromatography to study drug interactions with this serum protein. Entrapment was achieved based on the physical containment of AGP in hydrazide-activated porous silica supports and by using mildly oxidized glycogen as a capping agent. The conditions needed for this process were examined and optimized. When this type of AGP column was used in binding studies, the association equilibrium constant (Ka) measured by frontal analysis at pH 7.4 and 37°C for carbamazepine with AGP was found to be 1.0 (±0.5)×10(5)M(-1), which agreed with a previously reported value of 1.0 (±0.1)×10(5)M(-1). Binding studies based on zonal elution were conducted for several other drugs with such columns, giving equilibrium constants that were consistent with literature values. An entrapped AGP column was also used in combination with a column containing entrapped HSA in a screening assay format to compare the binding of various drugs to AGP and HSA. These results also agreed with previous data that have been reported in literature for both of these proteins. The same entrapment method could be extended to other proteins and to the investigation of additional types of drug-protein interactions. Potential applications include the rapid quantitative analysis of biological interactions and the high-throughput screening of drug candidates for their binding to a given protein. Copyright © 2015 Elsevier B.V. All rights reserved.

ProteomeVis: a web app for exploration of protein properties from structure to sequence evolution across organisms' proteomes.

PubMed

Razban, Rostam M; Gilson, Amy I; Durfee, Niamh; Strobelt, Hendrik; Dinkla, Kasper; Choi, Jeong-Mo; Pfister, Hanspeter; Shakhnovich, Eugene I

2018-05-08

Protein evolution spans time scales and its effects span the length of an organism. A web app named ProteomeVis is developed to provide a comprehensive view of protein evolution in the S. cerevisiae and E. coli proteomes. ProteomeVis interactively creates protein chain graphs, where edges between nodes represent structure and sequence similarities within user-defined ranges, to study the long time scale effects of protein structure evolution. The short time scale effects of protein sequence evolution are studied by sequence evolutionary rate (ER) correlation analyses with protein properties that span from the molecular to the organismal level. We demonstrate the utility and versatility of ProteomeVis by investigating the distribution of edges per node in organismal protein chain universe graphs (oPCUGs) and putative ER determinants. S. cerevisiae and E. coli oPCUGs are scale-free with scaling constants of 1.79 and 1.56, respectively. Both scaling constants can be explained by a previously reported theoretical model describing protein structure evolution (Dokholyan et al., 2002). Protein abundance most strongly correlates with ER among properties in ProteomeVis, with Spearman correlations of -0.49 (p-value<10-10) and -0.46 (p-value<10-10) for S. cerevisiae and E. coli, respectively. This result is consistent with previous reports that found protein expression to be the most important ER determinant (Zhang and Yang, 2015). ProteomeVis is freely accessible at http://proteomevis.chem.harvard.edu. Supplementary data are available at Bioinformatics. shakhnovich@chemistry.harvard.edu.

Entrapment of Alpha1-Acid Glycoprotein in High-Performance Affinity Columns for Drug-Protein Binding Studies

PubMed Central

Bi, Cong; Jackson, Abby; Vargas-Badilla, John; Li, Rong; Rada, Giana; Anguizola, Jeanethe; Pfaunmiller, Erika; Hage, David S.

2015-01-01

A slurry-based method was developed for the entrapment of alpha1-acid glycoprotein (AGP) for use in high-performance affinity chromatography to study drug interactions with this serum protein. Entrapment was achieved based on the physical containment of AGP in hydrazide-activated porous silica supports and by using mildly oxidized glycogen as a capping agent. The conditions needed for this process were examined and optimized. When this type of AGP column was used in binding studies, the association equilibrium constant (Ka) measured by frontal analysis at pH 7.4 and 37°C for carbamazepine with AGP was found to be 1.0 (± 0.5) × 105 M−1, which agreed with a previously reported value of 1.0 (± 0.1) × 105 M−1. Binding studies based on zonal elution were conducted for several other drugs with such columns, giving equilibrium constants that were consistent with literature values. An entrapped AGP column was also used in combination with a column containing entrapped HSA in a screening assay format to compare the binding of various drugs to AGP and HSA. These results also agreed with previous data that have been reported in literature for both of these proteins. The same entrapment method could be extended to other proteins and to the investigation of additional types of drug-protein interactions. Potential applications include the rapid quantitative analysis of biological interactions and the high-throughput screening of drug candidates for their binding to a given protein. PMID:26627938

Extracellular DNA impedes the transport of vancomycin in Staphylococcus epidermidis biofilms preexposed to subinhibitory concentrations of vancomycin.

PubMed

Doroshenko, Natalya; Tseng, Boo Shan; Howlin, Robert P; Deacon, Jill; Wharton, Julian A; Thurner, Philipp J; Gilmore, Brendan F; Parsek, Matthew R; Stoodley, Paul

2014-12-01

Staphylococcus epidermidis biofilm formation is responsible for the persistence of orthopedic implant infections. Previous studies have shown that exposure of S. epidermidis biofilms to sub-MICs of antibiotics induced an increased level of biofilm persistence. BODIPY FL-vancomycin (a fluorescent vancomycin conjugate) and confocal microscopy were used to show that the penetration of vancomycin through sub-MIC-vancomycin-treated S. epidermidis biofilms was impeded compared to that of control, untreated biofilms. Further experiments showed an increase in the extracellular DNA (eDNA) concentration in biofilms preexposed to sub-MIC vancomycin, suggesting a potential role for eDNA in the hindrance of vancomycin activity. Exogenously added, S. epidermidis DNA increased the planktonic vancomycin MIC and protected biofilm cells from lethal vancomycin concentrations. Finally, isothermal titration calorimetry (ITC) revealed that the binding constant of DNA and vancomycin was 100-fold higher than the previously reported binding constant of vancomycin and its intended cellular d-Ala-d-Ala peptide target. This study provides an explanation of the eDNA-based mechanism of antibiotic tolerance in sub-MIC-vancomycin-treated S. epidermidis biofilms, which might be an important factor for the persistence of biofilm infections. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Preplanetary Nebulae: A Hubble Space Telescope Imaging Survey and a New Morphological Classification System

NASA Technical Reports Server (NTRS)

Sahai, Raghvendra; Morris, Mark; Sanchez Contreras, Carmen; Claussen, Mark

2007-01-01

Using the Hubble Space Telescope (HST ), we have carried out a survey of candidate preplanetary nebulae (PPNs). We report here our discoveries of objects having well-resolved geometric structures, and we use the large sample of PPNs now imaged with HST (including previously studied objects in this class) to devise a comprehensive morphological classification system for this category of objects. The wide variety of aspherical morphologies which we have found for PPNs are qualitatively similar to those found for young planetary nebulae (PNs) in previous surveys. We also find prominent halos surrounding the central aspherical shapes in many of our objects; these are direct signatures of the undisturbed circumstellar envelopes of the progenitor AGB stars. Although the majority of these have surface brightness distributions consistent with a constant mass-loss rate with a constant expansion velocity, there are also examples of objects with varying mass-loss rates. As in our surveys of young PNs, we find no round PPNs. The similarities in morphologies between our survey objects and young PNs supports the view that the former are the progenitors of aspherical PNs. This suggests that the primary shaping of a PN does not occur during the PN phase via the fast radiative wind of the hot central star, but significantly earlier in its evolution.

Spectroscopy of the 1/2 2S → 3/2 2P transition in Yb ii: Isotope shifts, hyperfine splitting, and branching ratios

NASA Astrophysics Data System (ADS)

Feldker, T.; Fürst, H.; Ewald, N. V.; Joger, J.; Gerritsma, R.

2018-03-01

We report on spectroscopic results on the 1/2 2S → 3/2 2P transition in single trapped Yb+ ions. We measure the isotope shifts for all stable Yb+ isotopes except +173Yb, as well as the hyperfine splitting of the 3/2 2P state in +171Yb. Our results are in agreement with previous measurements but are a factor of 5-9 more precise. For the hyperfine constant A (3/2 2P)=875.4 (10 )MHz our results also agree with previous measurements but deviate significantly from theoretical predictions. We present experimental results on the branching ratios for the decay of the 3/2 2P state. We find branching fractions for the decay to the 3/2 2D state and 5/2 2D state of 0.17(1)% and 1.08(5)%, respectively, in rough agreement with theoretical predictions. Furthermore, we measured the isotope shifts of the 7/2 2F →1D[5/2 ] 5 /2 transition and determine the hyperfine structure constant for the 1D[5/2 ] 5 /2 state in +171Yb to be A (1D[5/2 ] 5 /2)=-107 (6 ) MHz .

Laboratory Studies of Vibrational Relaxation: Important Insights for Mesospheric OH

NASA Astrophysics Data System (ADS)

Kalogerakis, K. S.; Matsiev, D.

2016-12-01

The hydroxyl radical has a key role in the chemistry and energetics of the Earth's middle atmosphere. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen and their temperature dependence is absolutely critical for understanding mesospheric OH and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental approaches to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Previous work in our laboratory indicated that the total removal rate constant for OH(v = 9) + O at room temperature is more than one order of magnitude larger than that for removal by O2. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the Meinel OH(v) emissions. We will report our most recent laboratory experiments that corroborate the aforementioned result for fast OH(v = 9) + O and provide important new insights on the mechanistic pathways involved. We will also highlight relevant atmospheric implications, including warranted revisions of current mesospheric OH models. Research supported by SRI International Internal R&D and NSF Aeronomy grant AGS-1441896. Previously supported by NASA Geospace Science grant NNX12AD09G.

Decay channels of Al L sub 2,3 excitons and the absence of O K excitons in. alpha. -Al sub 2 O sub 3

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

O'Brien, W.L.; Jia, J.; Dong, Q.

1991-12-15

The Al {ital L}{sub 2,3} and O {ital K} thresholds for single-crystal {alpha}-Al{sub 2}O{sub 3} have been studied by photoemission. Energy-distribution curves, constant-initial-state (CIS), and constant-final-state (CFS) spectra are reported and compared to the absorption spectrum reported previously. An exciton appears as a doublet at threshold in the Al {ital L}{sub 2,3} CFS, CIS, and absorption spectra. The details of the Al {ital L}{sub 2,3} CFS spectrum and absorption spectrum are similar, while the exciton is the only feature present in the CIS spectrum. Comparisons of the various Al {ital L}{sub 2,3} spectra allow the probabilities of different exciton decaymore » channels to be determined. The probability for nonradiative direct recombination of the exciton is found to be (8{plus minus}1)% and the probability for Auger decay of the exciton is found to be (72{plus minus}20)%. Comparisons of the O {ital K} CIS and CFS spectra suggest that no O {ital K} exciton is formed.« less

Mechanism of Metal Ion Activation of the Diphtheria Toxin Repressor DtxR

NASA Astrophysics Data System (ADS)

D'Aquino, J. Alejandro; Ringe, Dagmar

2006-08-01

The diphtheria toxin repressor, DtxR, is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear (1 - 3). Calorimetric techniques have demonstrated that while binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 × 10-7, binding site 2 (primary) is a low affinity binding site with a binding constant of 6.3 × 10-4. These two binding sites act independently and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A,C102D), reported here and the previously reported DtxR(H79A) (4) has allowed us to propose a mechanism of metal ion activation for DtxR.

Synthesis of Zn-In-S Quantum Dots with Tunable Composition and Optical Properties.

PubMed

Wang, Xianliang; Damasco, Jossana; Shao, Wei; Ke, Yujie; Swihart, Mark T

2016-03-03

II-III-VI semiconductors are of interest due to their chemical stability and composition-tunable optical properties. Here, we report a methodology for the synthesis of monodisperse zinc-indium-sulfide (ZIS) alloy quantum dots (QDs, mean diameter from ∼2 to 3.5 nm) with an In content substantially below that of the stoichiometric ZnIn2 S4 compound. The effects of indium incorporation on the size, lattice constant, and optical properties of ZIS QDs are elucidated. In contrast to previous reports, we employ sulfur dissolved in oleic acid as the sulfur donor rather than thioacetamide (TAA). The size of the ZIS QDs and their crystal lattice constant increased with increasing In incorporation, but they maintained the cubic sphalerite phase of ZnS, rather than the hexagonal phase typical of ZnIn2 S4 . The QDs' absorbance onset at UV wavelengths red-shifts with increasing In content and the accompanying increase in NC size. The ZIS NCs and related materials, whose synthesis is enabled by the approach presented here, provide new opportunities to apply II-III-VI semiconductors in solution-processed UV optoelectronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on improving the turbidity measurement of the absolute coagulation rate constant.

PubMed

Sun, Zhiwei; Liu, Jie; Xu, Shenghua

2006-05-23

The existing theories dealing with the evaluation of the absolute coagulation rate constant by turbidity measurement were experimentally tested for different particle-sized (radius = a) suspensions at incident wavelengths (lambda) ranging from near-infrared to ultraviolet light. When the size parameter alpha = 2pi a/lambda > 3, the rate constant data from previous theories for fixed-sized particles show significant inconsistencies at different light wavelengths. We attribute this problem to the imperfection of these theories in describing the light scattering from doublets through their evaluation of the extinction cross section. The evaluations of the rate constants by all previous theories become untenable as the size parameter increases and therefore hampers the applicable range of the turbidity measurement. By using the T-matrix method, we present a robust solution for evaluating the extinction cross section of doublets formed in the aggregation. Our experiments show that this new approach is effective in extending the applicability range of the turbidity methodology and increasing measurement accuracy.

Effect of delayed reporting of band recoveries on survival estimates

USGS Publications Warehouse

Anderson, David R.; Burnham, Kenneth P.

1980-01-01

Brownie et al. (U.S. Fish and Wildl. Serv., Resource Publ. 131, 1978) presented 14 models based on an array of explicit assumptions for the study of survival in avian populations. These methods are replacing the life table methods previously used to estimate survival rates (e.g., Burnham and Anderson, J. Wildl. Manage., 43: 356-366, 1979). The new methods allow survival or recovery rates, or both, to be constant, time-specific, or time- and age-specific. In studies to estimate survival rates for birds the data are often from recoveries of birds shot or found dead during the hunting season and reported to the Bird Banding Laboratory by sportsmen, conservation agency employees, or the general public. This note examines the bias in estimating annual survival due to a proportion of the recoveries being incorrectly reported a year late. Specifically, a few recoveries each year of, for example, adult male American Widgeon (Anas americana) banded in California are reported as being recovered in year i + 1 when in fact they were actually recovered the previous year i. Delayed reporting might typically be caused by people finding a band in their health clothing in the fall of the year and, being embarrassed about their failure to report the band when it was taken, report it a year late not mentioning the actual year of recovery. Heuristically, delayed reporting should bias estimated annual survival rates upwards because it appears from the data that the birds corresponding to the "delayed" recoveries actually lived an additional year.

High photoactive and visible-light responsive graphene/titanate nanotubes photocatalysts: preparation and characterization.

PubMed

Qianqian, Zhai; Tang, Bo; Guoxin, Hu

2011-12-30

A series of graphene/titanate nanotubes (TNTs) photocatalysts using graphene and nanoscale TiO(2) or P25 as original materials were fabricated by hydrothermal method. Both low hydrothermal temperature and proper amount of graphene are propitious to better photoactivity. The photocatalytic activities of these nanocomposites far exceed that of P25, pure TNTs and reported TiO(2)-based nanocomposites for the degradation of Rhodamine-B under visible-light irradiation. These prepared photocatalysts were characterized by TEM, XRD, XPS, BET, FTIR and UV-vis diffuse reflection spectra, and the results indicate that the outstanding photoactivities in visible-light region result from sensitization effect of graphene rather than impurity level in the band gap of TNTs. Furthermore, large BET surface areas of these photocatalysts (almost 10 times larger than that of previously reported graphene/TiO(2) nanoparticles) evidently enhance their absorption abilities and photocatalytic performances (the rate constants of degrading Rhodamine-B are at least 5 times higher than that of previously reported photocatalysts). These photocatalysts show good stability, and their photoactivities do not obviously decrease after four times of repeated uses. A detailed photocatalytic mechanism is suggested, as well. Copyright © 2011 Elsevier B.V. All rights reserved.

Investigating flavour characteristics of British ale yeasts: techniques, resources and opportunities for innovation

PubMed Central

Parker, Neva; James, Steve; Dicks, Jo; Bond, Chris; Nueno-Palop, Carmen; White, Chris; Roberts, Ian N

2015-01-01

Five British ale yeast strains were subjected to flavour profiling under brewery fermentation conditions in which all other brewing parameters were kept constant. Significant variation was observed in the timing and quantity of flavour-related chemicals produced. Genetic tests showed no evidence of hybrid origins in any of the strains, including one strain previously reported as a possible hybrid of Saccharomyces cerevisiae and S. bayanus. Variation maintained in historical S. cerevisiae ale yeast collections is highlighted as a potential source of novelty in innovative strain improvement for bioflavour production. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25361168

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

Luo Hailu; Zhou Xinxing; Shu Weixing

We theorize an enhanced and switchable spin Hall effect (SHE) of light near the Brewster angle on reflection and demonstrate it experimentally. The obtained spin-dependent splitting reaches 3200 nm near the Brewster angle, which is 50 times larger than the previously reported values in refraction. We find that the amplifying factor in weak measurement is not a constant, which is significantly different from that in refraction. As an analogy of SHE in an electronic system, a switchable spin accumulation in SHE of light is detected. We were able to switch the direction of the spin accumulations by slightly adjusting themore » incident angle.« less

Structural and electronic properties of half-metallic rare-earth perovskites

NASA Astrophysics Data System (ADS)

Khandy, Shakeel Ahmad; Islam, Ishtihadah; Bhat, Tahir Mohiuddin; Yousuf, Saleem; Gupta, Dinesh C.

2018-05-01

Systemic investigation of structural parameters and electronic properties inclusive of band profiles for BaPaO3 and BaUO3 have been performed. The empirical as well as DFT calculated lattice constants are in agreement with the previously reported results. The critical energy values confirm that the BaPaO3 has lesser migration energy than BaUO3. Both, these materials show a semiconducting, direct band gap in the low spin state with 2.3 eV for BaUO3 and for BaPaO3, its value is 3.9 eV.

Vehicle test report: Jet Industries Electra Van 600

NASA Technical Reports Server (NTRS)

Price, T. W.; Wirth, V. A., Jr.

1982-01-01

The Electra Van 600, an electric vehicle, was tested. Tests were performed to characterize parameters of the Electra Van 600 and to provide baseline data to be used for comparison of improved batteries and to which will be incorporated into the vehicle. The vehicle tests concentrated on the electrical drive subsystem, the batteries, controller, and motor; coastdowns to characterize the road load and range evaluation for cyclic and constant speed conditions; and qualitative performance was evaluated. It is found that the Electra Van 600 range performance is approximately equal to the majority of the vehicles tested previously.

Cold molecule spectroscopy for constraining the evolution of the fine structure constant.

PubMed

Hudson, Eric R; Lewandowski, H J; Sawyer, Brian C; Ye, Jun

2006-04-14

We report precise measurements of ground-state, Lambda-doublet microwave transitions in the hydroxyl radical molecule (OH). Utilizing slow, cold molecules produced by a Stark decelerator we have improved over the precision of the previous best measurement 25-fold for the F'=2-->F=2 transition, yielding (1 667 358 996 +/- 4)Hz, and by tenfold for the F'=1-->F=1 transition, yielding (1 665 401 803 +/-12)Hz. Comparing these laboratory frequencies to those from OH megamasers in interstellar space will allow a sensitivity of 1 ppm for Delta(alpha/alpha) over approximately 10(10) yr.

Proceedings SPIE: Conference Digest, International Conference on Infrared and Millimeter Waves (18th) Held in Colchester, United Kingdom on 6-10 September 1993. Volume 2104

DTIC Science & Technology

1993-09-10

effective dielectric constant appears to decrease upon the substitution of PbO, 1. INRODUCTION In V2 05 - TeO2 glasses several studies on equilibrium... glass increases as TeOg is partially replaced by PbO. Previous studies on V20 5 - TeO2 system 4.5 have reported three Infrared absorption bands at 1010...Laboratory, Dr, K,S. Krishnan Road, New Delhi 110012, India. Th4., REFLECTANCE STUDY OF TM,O. GLASSES - AMemon, M,N.Khan, SAI-Dallal, Department of

Spectral reproducibility and quantification of peptides in MALDI of samples prepared by micro-spotting.

PubMed

Bae, Yong Jin; Park, Kyung Man; Ahn, Sung Hee; Moon, Jeong Hee; Kim, Myung Soo

2014-08-01

Previously, we reported that MALDI spectra of peptides became reproducible when temperature was kept constant. Linear calibration curves derived from such spectral data could be used for quantification. Homogeneity of samples was one of the requirements. Among the three popular matrices used in peptide MALDI [i.e., α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), and sinapinic acid (SA)], homogeneous samples could be prepared by conventional means only for CHCA. In this work, we showed that sample preparation by micro-spotting improved the homogeneity for all three cases.

Structured settlement annuities, part 2: mortality experience 1967--95 and the estimation of life expectancy in the presence of excess mortality.

PubMed

Singer, R B; Schmidt, C J

2000-01-01

the mortality experience for structured settlement (SS) annuitants issued both standard (Std) and substandard (SStd) has been reported twice previously by the Society of Actuaries (SOA), but the 1995 mortality described here has not previously been published. We describe in detail the 1995 SS mortality, and we also discuss the methodology of calculating life expectancy (e), contrasting three different life-table models. With SOA permission, we present in four tables the unpublished results of its 1995 SS mortality experience by Std and SStd issue, sex, and a combination of 8 age and 6 duration groups. Overall results on mortality expected from the 1983a Individual Annuity Table showed a mortality ratio (MR) of about 140% for Std cases and about 650% for all SStd cases. Life expectancy in a group with excess mortality may be computed by either adding the decimal excess death rate (EDR) to q' for each year of attained age to age 109 or multiplying q' by the decimal MR for each year to age 109. An example is given for men age 60 with localized prostate cancer; annual EDRs from a large published cancer study are used at duration 0-24 years, and the last EDR is assumed constant to age 109. This value of e is compared with e from constant initial values of EDR or MR after the first year. Interrelations of age, sex, e, and EDR and MR are discussed and illustrated with tabular data. It is shown that a constant MR for life-table calculation of e consistently overestimates projected annual mortality at older attained ages and underestimates e. The EDR method, approved for reserve calculations, is also recommended for use in underwriting conversion tables.

Laser flash photolysis of ozone - O/1D/ quantum yields in the fall-off region 297-325 nm

NASA Technical Reports Server (NTRS)

Brock, J. C.; Watson, R. T.

1980-01-01

The wavelength dependence of the quantum yield for O(1D) production from ozone photolysis has been determined between 297.5 nm and 325 nm in order to resolve serious discrepancies among previous studies. The results of this investigation are compared to earlier work by calculating atmospheric production rate constants for O(1D). It is found that for the purpose of calculating this rate constant, there is now good agreement among three studies at 298 K. Furthermore, it appears that previous data on the temperature dependence of the O(1D) quantum yield fall-off is adequate for determining the vertical profile of the O(1D) production rate constant. Several experimental difficulties associated with using NO2(asterisk) chemiluminescence to monitor O(1D) have been identified.

Mechanisms for vasopressin effects on intraocular pressure in anesthetized rats

NASA Technical Reports Server (NTRS)

Balaban, C. D.; Palm, D. E.; Shikher, V.; Searles, R. V.; Keil, L. C.; Severs, W. B.

1997-01-01

Continuous intracameral infusions of a balanced salt solution (0.175 microliter min-1) have been reported to raise intraocular pressure (IOP) in anesthetized rats. Palm et al. (1995) previously reported that this effect was attenuated significantly by inclusion of arginine-vasopressin (AVP, 10 ng 0.175 microliter-1) in the infusate. This study used experimental and computer simulation methods to investigate factors underlying these changes in IOP. First, constant intracameral infusions of artificial cerebrospinal fluid (aCSF) at different fixed rates (0.049-0.35 microliter min-1) were used to estimate the outflow resistance. Secondly, IOP responses were measured during an 2 hr intracameral infusion of either aCSF or AVP that was the sum of a small constant component (0.05 microliter min-1) and a larger periodic component (0.25 microliter min-1, cycling for 4 min on, then 4 min off); the mean infusion rate was 0.175 microliter min-1. As shown previously for 0.175 microliter min-1 constant infusions, the periodic aCSF infusion induced a significant rise in IOP that was attenuated by AVP administration. Complex demodulation analysis and the estimated gain parameter of a second order transfer function fit to the periodic responses indicated that outflow resistance increased significantly during the infusions in both aCSF and AVP groups, but that the indices of resistance did not differ significantly between aCSF and AVP infused eyes. This finding implies that changes in outflow resistance do not explain the difference in IOP responses to intracameral aCSF and AVP. The two responses differed significantly, though, in damping factors, such that the aCSF responses were considerably more underdamped than the AVP responses. It is hypothesized that aCSF-induced increase in IOP reflects both (1) a small component reflecting increased outflow resistance and (2) a larger non-resistive component. Since the non-resistive component is insensitive to pretreatment with acetazolamide, it is suggested that the aCSF-induced elevation in IOP reflects primarily vascular perfusion changes that are reduced by local vasoconstrictor actions of AVP. The latter mechanism likely maintains vascular perfusion of the globe when intraocular hypertension develops.

Aptamer Recognition of Multiplexed Small-Molecule-Functionalized Substrates.

PubMed

Nakatsuka, Nako; Cao, Huan H; Deshayes, Stephanie; Melkonian, Arin Lucy; Kasko, Andrea M; Weiss, Paul S; Andrews, Anne M

2018-05-31

Aptamers are chemically synthesized oligonucleotides or peptides with molecular recognition capabilities. We investigated recognition of substrate-tethered small-molecule targets, using neurotransmitters as examples, and fluorescently labeled DNA aptamers. Substrate regions patterned via microfluidic channels with dopamine or L-tryptophan were selectively recognized by previously identified dopamine or L-tryptophan aptamers, respectively. The on-substrate dissociation constant determined for the dopamine aptamer was comparable to, though slightly greater than the previously determined solution dissociation constant. Using pre-functionalized neurotransmitter-conjugated oligo(ethylene glycol) alkanethiols and microfluidics patterning, we produced multiplexed substrates to capture and to sort aptamers. Substrates patterned with L-DOPA, L-DOPS, and L-5-HTP enabled comparison of the selectivity of the dopamine aptamer for different targets via simultaneous determination of in situ binding constants. Thus, beyond our previous demonstrations of recognition by protein binding partners (i.e., antibodies and G-protein-coupled receptors), strategically optimized small-molecule-functionalized substrates show selective recognition of nucleic acid binding partners. These substrates are useful for side-by-side target comparisons, and future identification and characterization of novel aptamers targeting neurotransmitters or other important small-molecules.

The vanishing limit of the square-well fluid: The adhesive hard-sphere model as a reference system

NASA Astrophysics Data System (ADS)

Largo, J.; Miller, M. A.; Sciortino, F.

2008-04-01

We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width δ as small as 0.005 times the particle diameter σ. For small δ, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on δ. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density ρc is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5δ)σ. The possibility of describing the δ →0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.

The vanishing limit of the square-well fluid: the adhesive hard-sphere model as a reference system.

PubMed

Largo, J; Miller, M A; Sciortino, F

2008-04-07

We report a simulation study of the gas-liquid critical point for the square-well potential, for values of well width delta as small as 0.005 times the particle diameter sigma. For small delta, the reduced second virial coefficient at the critical point B2*c is found to depend linearly on delta. The observed weak linear dependence is not sufficient to produce any significant observable effect if the critical temperature Tc is estimated via a constant B2*c assumption, due to the highly nonlinear transformation between B2*c and Tc. This explains the previously observed validity of the law of corresponding states. The critical density rho c is also found to be constant when measured in units of the cube of the average distance between two bonded particles (1+0.5 delta)sigma. The possibility of describing the delta-->0 dependence with precise functional forms provides improved accurate estimates of the critical parameters of the adhesive hard-sphere model.

A Combined Density Functional Theory and Spectrophotometry Study of the Bonding Interactions of [NpO 2·M] 4+ Cation–Cation Complexes

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

Freiderich, John W.; Burn, Adam G.; Martin, Leigh R.

The equilibrium constants for [NpO 2M∙] 4+ (M = Al 3+, In 3+, Sc 3+, Fe 3+) in μ = 10 M nitric acid and [NpO 2∙Ga] 4+ in μ = 10 M hydrochloric acid media have been determined. The trend in the interaction strength follows: Fe 3+ > Sc 3+ In 3+ > Ga 3+ Al 3+. These equilibrium constants are compared to those of previously reported values for NpO 2 + complexes with Cr 3+ and Rh 3+ within the literature. Thermodynamic parameters and bonding modes are discussed, with density functional theory and natural bond orbital analysis indicatingmore » that the NpO 2 + dioxocation acts as a -donor with transition-metal cations and a sigma donor with group 13 cations. The small changes in electron-donating ability is modulated by the overlap with the coordinating metal ion's valence atomic orbitals.« less

Polarographic determination of lead hydroxide formation constants at low ionic strength

USGS Publications Warehouse

Lind, Carol J.

1978-01-01

Values of formation constants for lead hydroxide at 25 ??C were calculated from normal pulse polarographic measurements of 10-6 M lead in 0.01 M sodium perchlorate. The low concentrations simulate those found in many freshwaters, permitting direct application of the values when considering distributions of lead species. The precise evaluation of species distribution in waters at other ionic strengths requires activity coefficient corrections. As opposed to much of the previously published work done at high ionic strength, the values reported here were obtained at low ionic strength, permitting use of smaller and better defined activity coefficient corrections. These values were further confirmed by differential-pulse polarography and differential-pulse anodic stripping voltammetry data. The logs of the values for ??1??? ??2???, and ??3??? were calculated to be 6.59, 10.80, and 13.63, respectively. When corrected to zero ionic strength these values were calculated to be 6.77, 11.07, and 13.89, respectively.

Studies of Inhibition of Intestinal Absorption of Radioactive Strontium

PubMed Central

Skoryna, Stanley C.; Paul, T. M.; Waldron-Edward, Deirdre

1965-01-01

A method is reported which permits selective suppression of absorption of radioactive strontium from ingested food material, allowing calcium to be available to the body. Studies were carried out on the inhibitory effect of various amounts of sodium alginate and the dose-response relationship of Sr89 and bone uptake. The results obtained indicated that under laboratory conditions sodium alginate effectively reduces Sr89 uptake in a constant proportion. This effect was observed at the three levels of administration of 1.4%, 12% and 24% of sodium alginate. The linear relationship between the dosage of the radioisotope and the bone uptake in the presence of sodium alginate suggests that the same proportion is maintained at the lower levels of intake of radioactive strontium. Previous studies with small constant doses of sodium alginate were extended in rats to a period corresponding approximately to three years of human life span. Low doses were sufficient to reduce appreciably bone uptake of radiostrontium. PMID:14341649

Continuous treatment of high strength wastewaters using air-cathode microbial fuel cells.

PubMed

Kim, Kyoung-Yeol; Yang, Wulin; Evans, Patrick J; Logan, Bruce E

2016-12-01

Treatment of low strength wastewaters using microbial fuel cells (MFCs) has been effective at hydraulic retention times (HRTs) similar to aerobic processes, but treatment of high strength wastewaters can require longer HRTs. The use of two air-cathode MFCs hydraulically connected in series was examined to continuously treat high strength swine wastewater (7-8g/L of chemical oxygen demand) at an HRT of 16.7h. The maximum power density of 750±70mW/m 2 was produced after 12daysof operation. However, power decreased by 85% after 185d of operation due to serious cathode fouling. COD removal was improved by using a lower external resistance, and COD removal rates were substantially higher than those previously reported for a low strength wastewater. However, removal rates were inconsistent with first order kinetics as the calculated rate constant was an order of magnitude lower than rate constant for the low strength wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

Estimation of Free Radical Ionization Energies by the Kinetic Method and the Relationship between the Kinetic Method and the Hammett Equation.

PubMed

Chen, G; Wong, P; Cooks, R G

1997-09-01

Substituted 1,2-diphenylethanes undergo competitive dissociations upon electron ionization (EI) to generate substituted benzyl cation and benzyl radical pairs. Application of the kinetic method to the previous reported EI mass spectra of these covalently bound precursor ions (data are taken from McLafferty et al. J. Am. Chem. Soc. 1970, 92, 6867)) is used to estimate the ionization energies of substituted benzyl free radicals. A correlation is observed between the Hammett σ constant of the substituents and the kinetic method parameter, ln(k(x)/k(H)), where k(x) is the rate of fragmentation to give the substituted product ion and k(H) is the rate to give the benzyl ion itself. Systems involving weakly bound cluster ions, including proton-bound dimers of meta- and para-substituted pyridines and meta- and para-substituted anilines, and electron-bound dimers of meta- and para-substituted nitrobenzenes, also show good correlations between the kinetic method parameter and the Hammett σ constant.

Synthesis and improved photochromic properties of pyrazolones in the solid state by incorporation of halogen

NASA Astrophysics Data System (ADS)

Guo, Jixi; Yuan, Hui; Jia, Dianzeng; Guo, Mingxi; Li, Yinhua

2017-01-01

Four novel photochromic pyrazolones have been prepared by introducing halogen atoms as substituents on the benzene ring. All as-synthesized compounds exhibited excellent reversible photochromic performances in the solid state. Upon UV light irradiation, the as-synthesized compounds can change their structures from E-form to K-form with yellow coloration. Further processed by heating, they rapidly reverted to their initial states at 120 °С. Their photo-response and thermal bleaching kinetics were detailed investigated by UV absorption spectra. The results showed that the time constants were higher than that of our previously reported compounds at least one order of magnitude and the rate constants of the as-synthesized compounds were significantly influenced by the size and electronegativity of different halogen atoms. The fluorescence emission were modulated in a high degree via photoisomerization of pyrazolones, which might be due to the efficient energy transfer from E-form to K-form isomers for their partly overlaps between their E-form absorption spectra and K-form fluorescence spectra.

A Combined Density Functional Theory and Spectrophotometry Study of the Bonding Interactions of [NpO 2·M] 4+ Cation–Cation Complexes

DOE PAGES

Freiderich, John W.; Burn, Adam G.; Martin, Leigh R.; ...

2017-04-14

The equilibrium constants for [NpO 2M∙] 4+ (M = Al 3+, In 3+, Sc 3+, Fe 3+) in μ = 10 M nitric acid and [NpO 2∙Ga] 4+ in μ = 10 M hydrochloric acid media have been determined. The trend in the interaction strength follows: Fe 3+ > Sc 3+ In 3+ > Ga 3+ Al 3+. These equilibrium constants are compared to those of previously reported values for NpO 2 + complexes with Cr 3+ and Rh 3+ within the literature. Thermodynamic parameters and bonding modes are discussed, with density functional theory and natural bond orbital analysis indicatingmore » that the NpO 2 + dioxocation acts as a -donor with transition-metal cations and a sigma donor with group 13 cations. The small changes in electron-donating ability is modulated by the overlap with the coordinating metal ion's valence atomic orbitals.« less

Association of a Model Transmembrane Peptide Containing Gly in a Heptad Sequence Motif

PubMed Central

Lear, James D.; Stouffer, Amanda L.; Gratkowski, Holly; Nanda, Vikas; DeGrado, William F.

2004-01-01

A peptide containing glycine at a and d positions of a heptad motif was synthesized to investigate the possibility that membrane-soluble peptides with a Gly-based, left-handed helical packing motif would associate. Based on analytical ultracentrifugation in C14-betaine detergent micelles, the peptide did associate in a monomer-dimer equilibrium, although the association constant was significantly less than that reported for the right-handed dimer of the glycophorin A transmembrane peptide in similar detergents. Fluorescence resonance energy transfer (FRET) experiments conducted on peptides labeled at their N-termini with either tetramethylrhodamine (TMR) or 7-nitrobenz-2-oxa-1,3-diazole (NBD) also indicated association. However, analysis of the FRET data using the usual assumption of complete quenching for NBD-TMR pairs in the dimer could not be quantitatively reconciled with the analytical ultracentrifugation-measured dimerization constant. This led us to develop a general treatment for the association of helices to either parallel or antiparallel structures of any aggregation state. Applying this treatment to the FRET data, constraining the dimerization constant to be within experimental uncertainty of that measured by analytical ultracentrifugation, we found the data could be well described by a monomer-dimer equilibrium with only partial quenching of the dimer, suggesting that the helices are most probably antiparallel. These results also suggest that a left-handed Gly heptad repeat motif can drive membrane helix association, but the affinity is likely to be less strong than the previously reported right-handed motif described for glycophorin A. PMID:15315956

Constant DI pacing suppresses cardiac alternans formation in numerical cable models

NASA Astrophysics Data System (ADS)

Zlochiver, S.; Johnson, C.; Tolkacheva, E. G.

2017-09-01

Cardiac repolarization alternans describe the sequential alternation of the action potential duration (APD) and can develop during rapid pacing. In the ventricles, such alternans may rapidly turn into life risking arrhythmias under conditions of spatial heterogeneity. Thus, suppression of alternans by artificial pacing protocols, or alternans control, has been the subject of numerous theoretical, numerical, and experimental studies. Yet, previous attempts that were inspired by chaos control theories were successful only for a short spatial extent (<2 cm) from the pacing electrode. Previously, we demonstrated in a single cell model that pacing with a constant diastolic interval (DI) can suppress the formation of alternans at high rates of activation. We attributed this effect to the elimination of feedback between the pacing cycle length and the last APD, effectively preventing restitution-dependent alternans from developing. Here, we extend this idea into cable models to study the extent by which constant DI pacing can control alternans during wave propagation conditions. Constant DI pacing was applied to ventricular cable models of up to 5 cm, using human kinetics. Our results show that constant DI pacing significantly shifts the onset of both cardiac alternans and conduction blocks to higher pacing rates in comparison to pacing with constant cycle length. We also demonstrate that constant DI pacing reduces the propensity of spatially discordant alternans, a precursor of wavebreaks. We finally found that the protective effect of constant DI pacing is stronger for increased electrotonic coupling along the fiber in the sense that the onset of alternans is further shifted to higher activation rates. Overall, these results support the potential clinical applicability of such type of pacing in improving protocols of implanted pacemakers, in order to reduce the risk of life-threatening arrhythmias. Future research should be conducted in order to experimentally validate these promising results.

Charge transport and velocity distribution in ambipolar organic thin film Transistors based on a diketopyrrolopyrrole-benzothiadiazole copolymer

NASA Astrophysics Data System (ADS)

Ha, Tae-Jun; Sonar, Prashant; Singh, Samarendra Pratap; Dodabalapur, Ananth

2011-03-01

There have been reports of charge transport mechanisms in organic thin film transistors (OTFTs) focusing on steady-state characteristics but these measurements provide limited information. Time-resolved measurements can provide additional information in understanding transport mechanisms but existing reports have focused on unipolar organic characteristics. No previous reports on ambipolar organic devices have involved entire velocity distribution and charge transport mechanisms. Recently, we have fabricated ambipolar OTFTs based on a diketopyrrolopyrrole-benzothiadiazole copolymer (PDPP-TBT) with a field-effect mobility of more than 0.2 cm2 V- 1 s - 1 . Velocity distributions are measured by performing specialized dynamic measurements while keeping the RC-time constant of the measurement circuit small. This yields a distribution in arrival times of charge carriers from source to drain which can be converted to velocity distributions. We will also describe dynamic transport measurements on high-k-dielectric PDPP-TBT OTFTs.

Pre-service Teachers Learn the Nature of Science in Simulated Worlds

NASA Astrophysics Data System (ADS)

Marshall, Jill

2007-10-01

Although the Texas Essential Knowledge and Skills include an understanding of the nature of science as an essential goal of every high school science course, few students report opportunities to explore essential characteristics of science in their previous classes. A simulated-world environment (Erickson, 2005) allows students to function as working scientists and discover these essential elements for themselves (i.e. that science is evidence-based and involves testable conjectures, that theories have limitations and are constantly being modified based on new discoveries to more closely reflect the natural world.) I will report on pre-service teachers' exploration of two simulated worlds and resulting changes in their descriptions of the nature of science. Erickson (2005). Simulating the Nature of Science. Presentation at the 2005 Summer AAPT Meeting, Salt Lake City, UT.

Outcome of locking compression plates in humeral shaft nonunions

PubMed Central

Kumar, Malhar N; Ravindranath, V Pratap; Ravishankar, MR

2013-01-01

Background: Nonunion of diaphyseal fractures of the humerus are frequently seen in clinical practice (incidence of up to 15% in certain studies) and osteosynthesis using dynamic compression plates, intra medullary nails and Ilizarov fixators have been reported previously. Locking compression plates (LCP) are useful in the presence of disuse osteoporosis, segmental bone loss and cortical defects that preclude strong fixation. We report a prospective followup study of the outcome of the use of LCP for humeral nonunion following failed internal fixation in which implants other than LCP had been used. Materials and Methods: Twenty four patients with nonunion of humeral shaft fractures following failed internal fixation were included in the study. The mean followup period was 3.4 years (range: 2.4 to 5.7 years) and the minimum followup period was 2 years. Mean age of the patients was 41.04 years (range: 24 to 57 years). All 24 patients underwent osteosynthesis using LCP and autologous bone grafting (cortico-cancellous iliac crest graft combined with or without fibular strut graft). Main outcome measurements included radiographic assessment of fracture union and pre and postoperative functional evaluation using the modified Constant and Murley scoring system. Results: 23 out of 24 fractures united following osteosynthesis. Average time to union was 16 weeks (range: 10 to 28 weeks). Complications included delayed union (n = 2), transient radial nerve palsy (n = 2) and persistent nonunion (n = 1). Functional evaluation using the Constant and Murley score showed excellent results in 11, good in 10, fair in two and poor outcome in one patient. Conclusions: Locking compression plating and cancellous bone grafting is a reliable option for achieving union in humeral diaphyseal nonunion with failed previous internal fixation and results in good functional outcome in patients with higher physiological demands. PMID:23682176

A gravitational-wave standard siren measurement of the Hubble constant.

PubMed

2017-11-02

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817-a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first 'multi-messenger' astronomical observation. Such observations enable GW170817 to be used as a 'standard siren' (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic 'distance ladder': the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.

A gravitational-wave standard siren measurement of the Hubble constant

NASA Astrophysics Data System (ADS)

Abbott, B. P.; Abbott, R.; Abbott, T. D.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Afrough, M.; Agarwal, B.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allen, G.; Allocca, A.; Altin, P. A.; Amato, A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Angelova, S. V.; Antier, S.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Atallah, D. V.; Aufmuth, P.; Aulbert, C.; Aultoneal, K.; Austin, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Bae, S.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Banagiri, S.; Barayoga, J. C.; Barclay, S. E.; Barish, B. C.; Barker, D.; Barkett, K.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Bawaj, M.; Bayley, J. C.; Bazzan, M.; Bécsy, B.; Beer, C.; Bejger, M.; Belahcene, I.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Bero, J. J.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Biscoveanu, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Bode, N.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonilla, E.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bossie, K.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Branchesi, M.; Brau, J. E.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; Broida, J. E.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Bustillo, J. Calderón; Callister, T. A.; Calloni, E.; Camp, J. B.; Canepa, M.; Canizares, P.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Carney, M. F.; Diaz, J. Casanueva; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerdá-Durán, P.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chase, E.; Chassande-Mottin, E.; Chatterjee, D.; Chatziioannou, K.; Cheeseboro, B. D.; Chen, H. Y.; Chen, X.; Chen, Y.; Cheng, H.-P.; Chia, H.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, A. K. W.; Chung, S.; Ciani, G.; Ciolfi, R.; Cirelli, C. E.; Cirone, A.; Clara, F.; Clark, J. A.; Clearwater, P.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Cohen, D.; Colla, A.; Collette, C. G.; Cominsky, L. R.; Constancio, M.; Conti, L.; Cooper, S. J.; Corban, P.; Corbitt, T. R.; Cordero-Carrión, I.; Corley, K. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; Cowan, E. E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; Creighton, J. D. E.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Dálya, G.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; da Silva Costa, C. F.; Datrier, L. E. H.; Dattilo, V.; Dave, I.; Davier, M.; Davis, D.; Daw, E. J.; Day, B.; de, S.; Debra, D.; Degallaix, J.; de Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Demos, N.; Denker, T.; Dent, T.; de Pietri, R.; Dergachev, V.; De Rosa, R.; Derosa, R. T.; de Rossi, C.; Desalvo, R.; de Varona, O.; Devenson, J.; Dhurandhar, S.; Díaz, M. C.; di Fiore, L.; di Giovanni, M.; di Girolamo, T.; di Lieto, A.; di Pace, S.; di Palma, I.; di Renzo, F.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Dreissigacker, C.; Driggers, J. C.; Du, Z.; Ducrot, M.; Dupej, P.; Dwyer, S. E.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Estevez, D.; Etienne, Z. B.; Etzel, T.; Evans, M.; Evans, T. M.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fee, C.; Fehrmann, H.; Feicht, J.; Fejer, M. M.; Fernandez-Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Finstad, D.; Fiori, I.; Fiorucci, D.; Fishbach, M.; Fisher, R. P.; Fitz-Axen, M.; Flaminio, R.; Fletcher, M.; Fong, H.; Font, J. A.; Forsyth, P. W. F.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Ganija, M. R.; Gaonkar, S. G.; Garcia-Quiros, C.; Garufi, F.; Gateley, B.; Gaudio, S.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, D.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glover, L.; Goetz, E.; Goetz, R.; Gomes, S.; Goncharov, B.; González, G.; Castro, J. M. Gonzalez; Gopakumar, A.; Gorodetsky, M. L.; Gossan, S. E.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Gretarsson, E. M.; Groot, P.; Grote, H.; Grunewald, S.; Gruning, P.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Halim, O.; Hall, B. R.; Hall, E. D.; Hamilton, E. Z.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hannuksela, O. A.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hinderer, T.; Hoak, D.; Hofman, D.; Holt, K.; Holz, D. E.; Hopkins, P.; Horst, C.; Hough, J.; Houston, E. A.; Howell, E. J.; Hreibi, A.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Inta, R.; Intini, G.; Isa, H. N.; Isac, J.-M.; Isi, M.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kamai, B.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kapadia, S. J.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katolik, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kemball, A. J.; Kennedy, R.; Kent, C.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, K.; Kim, W.; Kim, W. S.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kinley-Hanlon, M.; Kirchhoff, R.; Kissel, J. S.; Kleybolte, L.; Klimenko, S.; Knowles, T. D.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kumar, S.; Kuo, L.; Kutynia, A.; Kwang, S.; Lackey, B. D.; Lai, K. H.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, H. W.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Linker, S. D.; Littenberg, T. B.; Liu, J.; Liu, X.; Lo, R. K. L.; Lockerbie, N. A.; London, L. T.; Lord, J. E.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lousto, C. O.; Lovelace, G.; Lück, H.; Lumaca, D.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macas, R.; Macfoy, S.; Machenschalk, B.; Macinnis, M.; MacLeod, D. M.; Hernandez, I. Magaña; Magaña-Sandoval, F.; Zertuche, L. Magaña; Magee, R. M.; Majorana, E.; Maksimovic, I.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markakis, C.; Markosyan, A. S.; Markowitz, A.; Maros, E.; Marquina, A.; Martelli, F.; Martellini, L.; Martin, I. W.; Martin, R. M.; Martynov, D. V.; Mason, K.; Massera, E.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matas, A.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McCuller, L.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McNeill, L.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Mejuto-Villa, E.; Melatos, A.; Mendell, G.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Miao, H.; Michel, C.; Middleton, H.; Mikhailov, E. E.; Milano, L.; Miller, A. L.; Miller, B. B.; Miller, J.; Millhouse, M.; Milovich-Goff, M. C.; Minazzoli, O.; Minenkov, Y.; Ming, J.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moffa, D.; Moggi, A.; Mogushi, K.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muñiz, E. A.; Muratore, M.; Murray, P. G.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nayak, R. K.; Neilson, J.; Nelemans, G.; Nelson, T. J. N.; Nery, M.; Neunzert, A.; Nevin, L.; Newport, J. M.; Newton, G.; Ng, K. K. Y.; Nguyen, T. T.; Nichols, D.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; North, C.; Nuttall, L. K.; Oberling, J.; O'Dea, G. D.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Okada, M. A.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; Ormiston, R.; Ortega, L. F.; O'Shaughnessy, R.; Ossokine, S.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; Pace, A. E.; Page, J.; Page, M. A.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, Howard; Pan, Huang-Wei; Pang, B.; Pang, P. T. H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Parida, A.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patil, M.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pirello, M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Porter, E. K.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Pratten, G.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rajbhandari, B.; Rakhmanov, M.; Ramirez, K. E.; Ramos-Buades, A.; Rapagnani, P.; Raymond, V.; Razzano, M.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Ren, W.; Reyes, S. D.; Ricci, F.; Ricker, P. M.; Rieger, S.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romel, C. L.; Romie, J. H.; Rosińska, D.; Ross, M. P.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Rutins, G.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sanchez, L. E.; Sanchis-Gual, N.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheel, M.; Scheuer, J.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schulte, B. W.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Seidel, E.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Shaddock, D. A.; Shaffer, T. J.; Shah, A. A.; Shahriar, M. S.; Shaner, M. B.; Shao, L.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, L. P.; Singh, A.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Smith, R. J. E.; Somala, S.; Son, E. J.; Sonnenberg, J. A.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staats, K.; Staley, A.; Steer, D.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stevenson, S. P.; Stone, R.; Stops, D. J.; Strain, K. A.; Stratta, G.; Strigin, S. E.; Strunk, A.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Suresh, J.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Tait, S. C.; Talbot, C.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Tasson, J. D.; Taylor, J. A.; Taylor, R.; Tewari, S. V.; Theeg, T.; Thies, F.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tonelli, M.; Tornasi, Z.; Torres-Forné, A.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tsang, K. W.; Tse, M.; Tso, R.; Tsukada, L.; Tsuna, D.; Tuyenbayev, D.; Ueno, K.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; van den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Vyatchanin, S. P.; Wade, A. R.; Wade, L. E.; Wade, M.; Walet, R.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, J. Z.; Wang, W. H.; Wang, Y. F.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wessel, E. K.; Weßels, P.; Westerweck, J.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; Whiting, B. F.; Whittle, C.; Wilken, D.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Wofford, J.; Wong, K. W. K.; Worden, J.; Wright, J. L.; Wu, D. S.; Wysocki, D. M.; Xiao, S.; Yamamoto, H.; Yancey, C. C.; Yang, L.; Yap, M. J.; Yazback, M.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zelenova, T.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.-H.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; Zimmerman, A. B.; Zucker, M. E.; Zweizig, J.; Foley, R. J.; Coulter, D. A.; Drout, M. R.; Kasen, D.; Kilpatrick, C. D.; Madore, B. F.; Murguia-Berthier, A.; Pan, Y.-C.; Piro, A. L.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rest, A.; Rojas-Bravo, C.; Shappee, B. J.; Siebert, M. R.; Simon, J. D.; Ulloa, N.; Annis, J.; Soares-Santos, M.; Brout, D.; Scolnic, D.; Diehl, H. T.; Frieman, J.; Berger, E.; Alexander, K. D.; Allam, S.; Balbinot, E.; Blanchard, P.; Butler, R. E.; Chornock, R.; Cook, E. R.; Cowperthwaite, P.; Drlica-Wagner, A.; Drout, M. R.; Durret, F.; Eftekhari, T.; Finley, D. A.; Fong, W.; Fryer, C. L.; García-Bellido, J.; Gill, M. S. S.; Gruendl, R. A.; Hanna, C.; Hartley, W.; Herner, K.; Huterer, D.; Kasen, D.; Kessler, R.; Li, T. S.; Lin, H.; Lopes, P. A. A.; Lourenço, A. C. C.; Margutti, R.; Marriner, J.; Marshall, J. L.; Matheson, T.; Medina, G. E.; Metzger, B. D.; Muñoz, R. R.; Muir, J.; Nicholl, M.; Nugent, P.; Palmese, A.; Paz-Chinchón, F.; Quataert, E.; Sako, M.; Sauseda, M.; Schlegel, D. J.; Secco, L. F.; Smith, N.; Sobreira, F.; Stebbins, A.; Villar, V. A.; Vivas, A. K.; Wester, W.; Williams, P. K. G.; Yanny, B.; Zenteno, A.; Abbott, T. M. C.; Abdalla, F. B.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Castander, F. J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Davis, C.; Depoy, D. L.; Desai, S.; Dietrich, J. P.; Estrada, J.; Fernandez, E.; Flaugher, B.; Fosalba, P.; Gaztanaga, E.; Gerdes, D. W.; Giannantonio, T.; Goldstein, D. A.; Gruen, D.; Gutierrez, G.; Hartley, W. G.; Honscheid, K.; Jain, B.; James, D. J.; Jeltema, T.; Johnson, M. W. G.; Kent, S.; Krause, E.; Kron, R.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Miller, C. J.; Miquel, R.; Neilsen, E.; Nord, B.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Roodman, A.; Rykoff, E. S.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Suchyta, E.; Tarle, G.; Thomas, D.; Thomas, R. C.; Troxel, M. A.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Zhang, Y.; Haislip, J. B.; Kouprianov, V. V.; Reichart, D. E.; Tartaglia, L.; Sand, D. J.; Valenti, S.; Yang, S.; Arcavi, Iair; Hosseinzadeh, Griffin; Howell, D. Andrew; McCully, Curtis; Poznanski, Dovi; Vasylyev, Sergiy; Tanvir, N. R.; Levan, A. J.; Hjorth, J.; Cano, Z.; Copperwheat, C.; de Ugarte-Postigo, A.; Evans, P. A.; Fynbo, J. P. U.; González-Fernández, C.; Greiner, J.; Irwin, M.; Lyman, J.; Mandel, I.; McMahon, R.; Milvang-Jensen, B.; O'Brien, P.; Osborne, J. P.; Perley, D. A.; Pian, E.; Palazzi, E.; Rol, E.; Rosetti, S.; Rosswog, S.; Rowlinson, A.; Schulze, S.; Steeghs, D. T. H.; Thöne, C. C.; Ulaczyk, K.; Watson, D.; Wiersema, K.; Lipunov, V. M.; Gorbovskoy, E.; Kornilov, V. G.; Tyurina, N.; Balanutsa, P.; Vlasenko, D.; Gorbunov, I.; Podesta, R.; Levato, H.; Saffe, C.; Buckley, D. A. H.; Budnev, N. M.; Gress, O.; Yurkov, V.; Rebolo, R.; Serra-Ricart, M.

2017-11-01

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observations enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.

Determination of the Avogadro constant by the XRCD method using a 28Si-enriched sphere

NASA Astrophysics Data System (ADS)

Kuramoto, Naoki; Mizushima, Shigeki; Zhang, Lulu; Fujita, Kazuaki; Azuma, Yasushi; Kurokawa, Akira; Okubo, Sho; Inaba, Hajime; Fujii, Kenichi

2017-10-01

To determine the Avogadro constant N A by the x-ray crystal density method, the density of a 28Si-enriched crystal was determined by absolute measurements of the mass and volume of a 1 kg sphere manufactured from the crystal. The mass and volume were determined by an optical interferometer and a vacuum mass comparator, respectively. The sphere surface was characterized by x-ray photoelectron spectroscopy and spectroscopic ellipsometry to derive the mass and volume of the Si core of the sphere excluding the surface layers. From the mass and volume, the density of the Si core was determined with a relative standard uncertainty of 2.3  ×  10-8. By combining the Si core density with the lattice constant and the molar mass of the sphere reported by the International Avogadro Coordination (IAC) project in 2015, a new value of 6.022 140 84(15)  ×  1023 mol-1 was obtained for N A with a relative standard uncertainty of 2.4  ×  10-8. To make the N A value determined in this work usable for a future adjustment of the fundamental constants by the CODATA Task Group on Fundamental Constants, the correlation of the new N A value with the N A values determined in our previous works was examined. The correlation coefficients with the values of N A determined by IAC in 2011 and 2015 were estimated to be 0.07 and 0.28, respectively. The correlation of the new N A value with the N A value determined by IAC in 2017 using a different 28Si-enriched crystal was also examined, and the correlation coefficient was estimated to be 0.21.

Experimental Solubility Approach to Determine PDMS-Water Partition Constants and PDMS Activity Coefficients.

PubMed

Grant, Sharon; Schacht, Veronika J; Escher, Beate I; Hawker, Darryl W; Gaus, Caroline

2016-03-15

Freely dissolved aqueous concentration and chemical activity are important determinants of contaminant transport, fate, and toxic potential. Both parameters are commonly quantified using Solid Phase Micro-Extraction (SPME) based on a sorptive polymer such as polydimethylsiloxane (PDMS). This method requires the PDMS-water partition constants, KPDMSw, or activity coefficient to be known. For superhydrophobic contaminants (log KOW >6), application of existing methods to measure these parameters is challenging, and independent measures to validate KPDMSw values would be beneficial. We developed a simple, rapid method to directly measure PDMS solubilities of solid contaminants, SPDMS(S), which together with literature thermodynamic properties was then used to estimate KPDMSw and activity coefficients in PDMS. PDMS solubility for the test compounds (log KOW 7.2-8.3) ranged over 3 orders of magnitude (4.1-5700 μM), and was dependent on compound class. For polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins (PCDDs), solubility-derived KPDMSw increased linearly with hydrophobicity, consistent with trends previously reported for less chlorinated congeners. In contrast, subcooled liquid PDMS solubilities, SPDMS(L), were approximately constant within a compound class. SPDMS(S) and KPDMSw can therefore be predicted for a compound class with reasonable robustness based solely on the class-specific SPDMS(L) and a particular congener's entropy of fusion, melting point, and aqueous solubility.

Aging and domain growth in K1-xLixTaO3 (x<=0.05)

NASA Astrophysics Data System (ADS)

Alberici-Kious, F.; Bouchaud, J.-P.; Cugliandolo, L. F.; Doussineau, P.; Levelut, A.

2000-12-01

We present experimental results on the dielectric constant in orientational glasses K1-xLixTaO3 (KLT) with x<=0.05, together with the detailed (analytic and numerical) study of a model which attributes the observed aging to the motion of the walls of polarization domains. We show that the dielectric constant after a positive temperature jump goes through a maximum as a function of the subsequent time. This observation and those previously reported (aging, cooling rate dependence, etc.) are compared with the predictions of the model, in which the variations of the dielectric constant are attributed to the change of polarization domain wall area. The total area decreases by domain growth and increases by nucleation of new small domains inside the larger ones. These two opposite variations are both hindered by static random fields (equivalent to energy barriers) due to the frozen dipoles borne by the off-center Li+ ions. Many results are well explained by the model with a single energy barrier. However, some effects can only be understood if a broad distribution of energy barriers is assumed. We use the experimental data to determine this distribution and find it to be unimodal with a width comparable to its most probable value.

Fourier Transform Spectroscopy of the A {sup 3}Π– X {sup 3}Σ{sup −} Transition of OH{sup +}

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

Hodges, James N.; Bernath, Peter F.

The OH{sup +} ion is of critical importance to the chemistry in the interstellar medium and is a prerequisite for the generation of more complex chemical species. Submillimeter and ultraviolet observations rely on high quality laboratory spectra. Recent measurements of the fundamental vibrational band and previously unanalyzed Fourier transform spectra of the near-ultraviolet A {sup 3}Π− X {sup 3}Σ{sup −} electronic spectrum, acquired at the National Solar Observatory at Kitt Peak in 1989, provide an excellent opportunity to perform a global fit of the available data. These new optical data are approximately four times more precise as compared to themore » previous values. The fit to the new data provides updated molecular constants, which are necessary to predict the OH{sup +} transition frequencies accurately to support future observations. These new constants are the first published using the modern effective Hamiltonian for a linear molecule. These new molecular constants allow for easy simulation of transition frequencies and spectra using the PGOPHER program. The new constants improve simulations of higher J -value infrared transitions, and represent an improvement of an order of magnitude for some constants pertaining to the optical transitions.« less

New photocycle intermediates in the photoactive yellow protein from Ectothiorhodospira halophila: picosecond transient absorption spectroscopy.

PubMed

Ujj, L; Devanathan, S; Meyer, T E; Cusanovich, M A; Tollin, G; Atkinson, G H

1998-07-01

Previous studies have shown that the room temperature photocycle of the photoactive yellow protein (PYP) from Ectothiorhodospira halophila involves at least two intermediate species: I1, which forms in <10 ns and decays with a 200-micros lifetime to I2, which itself subsequently returns to the ground state with a 140-ms time constant at pH 7 (Genick et al. 1997. Biochemistry. 36:8-14). Picosecond transient absorption spectroscopy has been used here to reveal a photophysical relaxation process (stimulated emission) and photochemical intermediates in the PYP photocycle that have not been reported previously. The first new intermediate (I0) exhibits maximum absorption at approximately 510 nm and appears in

Ionic strength dependence of the oxidation of SO2 by H2O2 in sodium chloride particles

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

Ali, Hashim M.; Iedema, Martin J.; Yu, Xiao-Ying

The reaction of sulfur dioxide and hydrogen peroxide in the presence of deliquesced (>75% RH) sodium particles was studied by utilizing a crossflow-mini reactor. The reaction kinetics was followed by observing chloride depletion in particles by computer-controlled scanning electron microscope with energy dispersive X-ray analysis, namely SEM/EDX. The reactions take place in concentrated mixed salt brine aerosols, for which no complete kinetic equilibrium data previously existed. We measured the Henry’s law solubility of H2O2 to close that gap. We also calculated the reaction rate as the particle transforms continuously from concentrated NaCl brine to eventually a mixed NaHSO4 plus H2SO4more » brine solution. The reaction rate of the SO2 oxidation by H2O2 was found to be influenced by the change in ionic strength as the particle undergoes compositional transformation, following closely the dependence of the third order rate constant on ionic strength as predicted rates using previously established rate equations. This is the first study that has measured the ionic strength dependence of sulfate formation (in non-aqueous media) from oxidation of mixed salt brine aerosols in the presence of H2O2. It also gives the first report of the Henry’s law constant of H2O2 dependence on ionic strength.« less

Comment on "Cosmogenic 180W variations in meteorites and re-assessment of a possible 184Os-180W decay system" by Cook, D.L., Kruijer, T., Leya, I., Kleine, T.

NASA Astrophysics Data System (ADS)

Peters, Stefan T. M.; Münker, Carsten; Becker, Harry; Schulz, Toni

2015-11-01

In their study on W isotope compositions of iron meteorites from the IVB and IIAB groups, Cook et al. (2014) suggested that the 180W isotope anomalies that have previously been reported for irons (Schulz et al., 2013; Peters et al., 2014) were largely caused by cosmic ray induced neutron capture and spallation reactions, and not by radioactive decay of 184Os as was argued by Peters et al. (2014). Cook et al. (2014) proposed a new decay constant value for 184Os (λ184Os = 3.15 ± 0.81 × 10-14 a-1) that is ca. a factor of 2 lower than previously suggested. However, based on a careful inspection of the Cook et al. (2014) model, we show here that cosmogenic W isotope heterogeneities have a negligible effect on the calculated decay constant from the dataset presented by Peters et al. (2014), as most iron meteorites examined in this study have cosmic ray exposure ages <100 Myrs. The bias between the two studies rather arises from the fact that Cook et al. (2014) estimated 184Os/184W ratios of their iron meteorite aliquots from literature Os and W concentration data, whereas in the Peters et al. (2014) study W isotope and Os-W concentration measurements were performed on the same digestion aliquot.

Geochemistry of manganese, iron, uranium, lead-210 and major ions in the Susquehanna River

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

Lewis, D.M.

1976-01-01

The change in water composition accompanying a change in discharge of large streams and the Susquehanna River results from the change in the proportions of the total flow composed of type waters of constant composition. This change in the flow proportions is due to the different hydrologic responses to precipitation inputs of basins underlain by different single rock types. The in-river precipitation of mine-drainage-injected Mn and Fe was studied at a pH of approximately 7. For Mn the removal from solution appears to be first order. The rate constant is 10/sup 3/ times greater than the extrapolated autocatalytic rate constantmore » of previous laboratory experiments. The study of the removal of Fe from solution yields a first order rate constant consistent with previous laboratory experiments. Lead-210 was used as a natural tracer to study the fate of trace metals.« less

Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration

PubMed Central

Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

2016-01-01

Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment. PMID:27256514

Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration.

PubMed

Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

2016-06-03

Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment.

Effects of bioirrigation of non-biting midges (Diptera: Chironomidae) on lake sediment respiration

NASA Astrophysics Data System (ADS)

Baranov, Viktor; Lewandowski, Jörg; Romeijn, Paul; Singer, Gabriel; Krause, Stefan

2016-06-01

Bioirrigation or the transport of fluids into the sediment matrix due to the activities of organisms such as bloodworms (larvae of Diptera, Chironomidae), has substantial impacts on sediment respiration in lakes. However, previous quantifications of bioirrigation impacts of Chironomidae have been limited by technical challenges such as the difficulty to separate faunal and bacterial respiration. This paper describes a novel method based on the bioreactive tracer resazurin for measuring respiration in-situ in non-sealed systems with constant oxygen supply. Applying this new method in microcosm experiments revealed that bioirrigation enhanced sediment respiration by up to 2.5 times. The new method is yielding lower oxygen consumption than previously reported, as it is only sensitive to aerobic heterotrophous respiration and not to other processes causing oxygen decrease. Hence it decouples the quantification of respiration of animals and inorganic oxygen consumption from microbe respiration in sediment.

Microstructures define melting of molybdenum at high pressures

NASA Astrophysics Data System (ADS)

Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

2017-03-01

High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature.

The unusual dynamics of parasite actin result from isodesmic polymerization

PubMed Central

Skillman, Kristen M.; Ma, Christopher I.; Fremont, Daved H.; Diraviyam, Karthikeyan; Cooper, John A.; Sept, David; Sibley, L. David

2013-01-01

Previous reports have indicated that parasite actins are short and inherently unstable, despite being required for motility. Here, we re-examine the polymerization properties of actin in Toxoplasma gondii (TgACTI), unexpectedly finding that it exhibits isodesmic polymerization in contrast to the conventional nucleation-elongation process of all previously studied actins from both eukaryotes and bacteria. TgACTI polymerization kinetics lacks both a lag phase and critical concentration, normally characteristic of actins. Unique among actins, the kinetics of assembly can be fit with a single set of rate constants for all subunit interactions, without need for separate nucleation and elongation rates. This isodesmic model accurately predicts the assembly, disassembly, and the size distribution of TgACTI filaments in vitro, providing a mechanistic explanation for actin dynamics in vivo. Our findings expand the repertoire of mechanisms by which actin polymerization is governed and offer clues about the evolution of self-assembling, stabilized protein polymers. PMID:23921463

Burning rate for steel-cased, pressed binderless HMX

NASA Technical Reports Server (NTRS)

Fifer, R. A.; Cole, J. E.

1980-01-01

The burning behavior of pressed binderless HMX laterally confined in 6.4 mm i.d. steel cases was measured over the pressure range 1.45 to 338 MPa in a constant pressure strand burner. The measured regression rates are compared to those reported previously for unconfined samples. It is shown that lateral confinement results in a several-fold decrease in the regression rate for the coarse particle size HMX above the transition to super fast regression. For class E samples, confinement shifts the transition to super fast regression from low pressure to high pressure. These results are interpreted in terms of the previously proposed progressive deconsolidation mechanism. Preliminary holographic photography and closed bomb tests are also described. Theoretical one dimensional modeling calculations were carried out to predict the expected flame height (particle burn out distance) as a function of particle size and pressure for binderless HMX burning by a progressive deconsolidation mechanism.

Microstructures define melting of molybdenum at high pressures

PubMed Central

Hrubiak, Rostislav; Meng, Yue; Shen, Guoyin

2017-01-01

High-pressure melting anchors the phase diagram of a material, revealing the effect of pressure on the breakdown of the ordering of atoms in the solid. An important case is molybdenum, which has long been speculated to undergo an exceptionally steep increase in melting temperature when compressed. On the other hand, previous experiments showed nearly constant melting temperature as a function of pressure, in large discrepancy with theoretical expectations. Here we report a high-slope melting curve in molybdenum by synchrotron X-ray diffraction analysis of crystalline microstructures, generated by heating and subsequently rapidly quenching samples in a laser-heated diamond anvil cell. Distinct microstructural changes, observed at pressures up to 130 gigapascals, appear exclusively after melting, thus offering a reliable melting criterion. In addition, our study reveals a previously unsuspected transition in molybdenum at high pressure and high temperature, which yields highly textured body-centred cubic nanograins above a transition temperature. PMID:28248309

Responses of polar organic compounds to different ionic environments in aqueous media are interrelated.

PubMed

Ferreira, L A; Chervenak, A; Placko, S; Kestranek, A; Madeira, P P; Zaslavsky, B Y

2014-11-14

Solubilities of 17 polar organic compounds in aqueous solutions of Na2SO4, NaCl, NaClO4, and NaSCN at the salt concentrations of up to 1.0-2.0 M were determined and the Setschenow constant, ksalt, values were estimated. It was found that NaClO4 may display both salting-in and salting-out effects depending on the particular compound structure. The Setschenow constant values for all the polar compounds examined in different salt solutions are found to be interrelated. Similar relationships were observed for partition coefficients of nonionic organic compounds in aqueous polyethylene glycol-sodium sulfate two-phase systems in the presence of different salt additives reported previously [Ferreira et al., J. Chromatogr. A, 2011, 1218, 5031], and for the effects of different salts on optical rotation of amino acids reported by Rossi et al. [J. Phys. Chem. B, 2007, 111, 10510]. In order to explain the observed relationships it is suggested that all the effects observed originate as responses of the compounds to the presence of a given ionic environment and its interaction with the compounds by forming direct or solvent-separated ionic pairs. The response is compound-specific and its strength is determined by the compound structure and the type (and concentration) of ions inducing the response.

Preparation and Electrical Properties of La0.9Sr0.1TiO3+δ

PubMed Central

Li, Wenzhi; Ma, Zhuang; Gao, Lihong; Wang, Fuchi

2015-01-01

La1−xSrxTiO3+δ (LST) has been studied in many fields, especially in the field of microelectronics due to its excellent electrical performance. Our previous theoretical simulated work has suggested that LST has good dielectric properties, but there are rare reports about this, especially experimental reports. In this paper, LST was prepared using a solid-state reaction method. The X-rays diffraction (XRD), scanning electron microscope (SEM), broadband dielectric spectroscopy, impedance spectroscopy and photoconductive measurement were used to characterize the sample. The results show that the values of dielectric parameters (the relative dielectric constant εr and dielectric loss tanδ), dependent on temperature, are stable under 350 °C and the value of the relative dielectric constant and dielectric loss are about 52–88 and 6.5 × 10−3, respectively. Its value of conductivity increases with rise in temperature, which suggests its negative temperature coefficient of the resistance. In addition, the band gap of LST is about 3.39 eV, so it belongs to a kind of wide-band-gap semiconductor materials. All these indicate that LST has anti-interference ability and good dielectric properties. It could have potential applications as an electronic material. PMID:28787995

Mechanism of Metal Ion Activation of the Diphtheria Toxin Repressor DtxR

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

D'Aquino,J.; Tetenbaum-Novatt, J.; White, A.

2005-01-01

The diphtheria toxin repressor (DtxR) is a metal ion-activated transcriptional regulator that has been linked to the virulence of Corynebacterium diphtheriae. Structure determination has shown that there are two metal ion binding sites per repressor monomer, and site-directed mutagenesis has demonstrated that binding site 2 (primary) is essential for recognition of the target DNA repressor, leaving the role of binding site 1 (ancillary) unclear. Calorimetric techniques have demonstrated that although binding site 1 (ancillary) has high affinity for metal ion with a binding constant of 2 x 10{sup -7}, binding site 2 (primary) is a low-affinity binding site with amore » binding constant of 6.3 x 10{sup -4}. These two binding sites act in an independent fashion, and their contribution can be easily dissected by traditional mutational analysis. Our results clearly demonstrate that binding site 1 (ancillary) is the first one to be occupied during metal ion activation, playing a critical role in stabilization of the repressor. In addition, structural data obtained for the mutants Ni-DtxR(H79A, C102D), reported here, and the previously reported DtxR(H79A) have allowed us to propose a mechanism of metal activation for DtxR.« less

[Current aspects of systemic lupus erythematosus in Dakar. About 74 cases].

PubMed

Fall, S; Dia, D; Ka, E F; Diallo, S; Pouye, A; Kane, A; Niang, A; Dieng, M T; Ka, M M; Diouf, B; Ndiaye, B; Moreira, Diop T

2007-01-01

previously reported studies on systemic lupus erythematosus in Senegal were more then ten years old and reported few cases of patients. Our objectives were to update epidemiological, clinical, laboratory and evolutive aspects of systemic lupus erythematosus throughout a study of 74 patients. we conducted a retrospective study in the internal medicine and the dermatology units of the university teaching hospital Aristide Le Dantec from January 1993 to December 2002. All patients with systemic lupus erythematosus according to the ACR criteria were included. Those who didn't meet ACR criteria were excluded. we included 74 patients; their mean age was 32 years and the sex ratio 0.1 (male to female). At the entry general symptoms were constants, and cutaneous signs were found in 96% of cases, joints signs in 58.1% and renal sign in 56.8%. Haematological and immunologic abnormalities were nearly constant. All the patients received corticosteroids and in 35.71% they had in addition immunosuppressive drugs. Shorts term evolution was satisfactory. At the medium term 27.02% of the patients were lost and 10.81% of them died. currents aspects of systemic lupus erythematosus in Dakar are improved by the early diagnosis when the disease is pauci-symptomatic and by the use immunosuppressive drugs in association with corticosteroids.

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters

PubMed Central

McAneny, Matthew J; Choi, Song Hee

2011-01-01

Summary The specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous organic mixtures with wide ranging nucleophilicity and ionizing power. For 1, we also report the first-order rate constants determined at different temperatures in pure ethanol (EtOH), methanol (MeOH), 80% EtOH, and in both 97% and 70% 2,2,2-trifluoroethanol (TFE). The enthalpy (ΔH≠) and entropy (ΔS≠) of activation values obtained from Arrhenius plots for 1 in these five solvents are reported. The specific rates of solvolysis were analyzed using the extended Grunwald–Winstein equation. Results obtained from correlation analysis using this linear free energy relationship (LFER) reinforce our previous suggestion that side-by-side addition–elimination and ionization mechanisms operate, and the relative importance is dependent on the type of chloro- or chlorothioformate substrate and the solvent. PMID:21647255

Constant and Progressive Time Delay Procedures for Teaching Children with Autism: A Literature Review

ERIC Educational Resources Information Center

Walker, Gabriela

2008-01-01

A review of 22 empirical studies examining the use of constant (CTD) and progressive (PTD) time delay procedures employed with children with autism frames an indirect analysis of the demographic, procedural, methodological, and outcome parameters of existing research. None of the previous manuscripts compared the two response prompting procedures.…

Theoretical study of the A prime 5Sigma(+)g and C double prime 5Pi u states of N2 - Implications for the N2 afterglow

NASA Technical Reports Server (NTRS)

Partridge, Harry; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Schwenke, David W.

1988-01-01

Theoretical spectroscopic constants are reported for the A prime 5Sigma(+)g and C double prime 5Pi u states of N2 based on CASSCF/MRCI calculations using large ANO Gaussian basis sets. The calculated A prime Sigma(+)g potential differs qualitatively from previous calculations in that the inner well is significantly deeper (De = 3450/cm). This deeper well provides considerable support for the suggestion of Berkowitz et al. (1956) that A prime 5Sigma(+)g is the primary precursor state involved in the yellow Lewis-Rayleigh afterglow of N2.

Three-dimensional turbulent-mixing-length modeling for discrete-hole coolant injection into a crossflow

NASA Technical Reports Server (NTRS)

Wang, C. R.; Papell, S. S.

1983-01-01

Three dimensional mixing length models of a flow field immediately downstream of coolant injection through a discrete circular hole at a 30 deg angle into a crossflow were derived from the measurements of turbulence intensity. To verify their effectiveness, the models were used to estimate the anisotropic turbulent effects in a simplified theoretical and numerical analysis to compute the velocity and temperature fields. With small coolant injection mass flow rate and constant surface temperature, numerical results of the local crossflow streamwise velocity component and surface heat transfer rate are consistent with the velocity measurement and the surface film cooling effectiveness distributions reported in previous studies.

Three-dimensional turbulent-mixing-length modeling for discrete-hole coolant injection into a crossflow

NASA Astrophysics Data System (ADS)

Wang, C. R.; Papell, S. S.

1983-09-01

Three dimensional mixing length models of a flow field immediately downstream of coolant injection through a discrete circular hole at a 30 deg angle into a crossflow were derived from the measurements of turbulence intensity. To verify their effectiveness, the models were used to estimate the anisotropic turbulent effects in a simplified theoretical and numerical analysis to compute the velocity and temperature fields. With small coolant injection mass flow rate and constant surface temperature, numerical results of the local crossflow streamwise velocity component and surface heat transfer rate are consistent with the velocity measurement and the surface film cooling effectiveness distributions reported in previous studies.

Fiber release from impacted graphite reinforced epoxy composites

NASA Technical Reports Server (NTRS)

Babinsky, T. C.

1980-01-01

Carbon fibers released from composites by aircraft fires and crashes can cause electrical shorts and consequent equipment damage. This report investigates less vigorous release mechanisms than that previously simulated by explosive burn/blast tests. When AS/3501-6 composites are impacted by various head and weight configurations of a pendulum impactor, less than 0.2 percent by weight of the original sample is released as single fibers. Other fiber release mechanisms studied were air blasts, constant airflow, torsion, flexural, and vibration of composite samples. The full significance of the low single fiber release rates found here is to be evaluated by NASA in their aircraft vulnerability studies.

Laser-stimulated electric quadrupole transitions in the molecular hydrogen ion H2+

NASA Astrophysics Data System (ADS)

Korobov, V. I.; Danev, P.; Bakalov, D.; Schiller, S.

2018-03-01

Molecular hydrogen ions are of metrological relevance due to the possibility of precise theoretical evaluation of their spectrum and of external-field-induced shifts. We report the results of the calculations of the rate of laser-induced electric quadrupole transitions between a large set of ro-vibrational states of H2+. The hyperfine and Zeeman structure of the E 2 transition spectrum and the effects of the laser polarization are treated in detail. The treatment is generally applicable to molecules in 2Σ states. We also present the nuclear spin-electron spin-coupling constants, computed with a precision ten times higher than previously obtained.

Serial dependence in the perception of attractiveness.

PubMed

Xia, Ye; Leib, Allison Yamanashi; Whitney, David

2016-12-01

The perception of attractiveness is essential for choices of food, object, and mate preference. Like perception of other visual features, perception of attractiveness is stable despite constant changes of image properties due to factors like occlusion, visual noise, and eye movements. Recent results demonstrate that perception of low-level stimulus features and even more complex attributes like human identity are biased towards recent percepts. This effect is often called serial dependence. Some recent studies have suggested that serial dependence also exists for perceived facial attractiveness, though there is also concern that the reported effects are due to response bias. Here we used an attractiveness-rating task to test the existence of serial dependence in perceived facial attractiveness. Our results demonstrate that perceived face attractiveness was pulled by the attractiveness level of facial images encountered up to 6 s prior. This effect was not due to response bias and did not rely on the previous motor response. This perceptual pull increased as the difference in attractiveness between previous and current stimuli increased. Our results reconcile previously conflicting findings and extend previous work, demonstrating that sequential dependence in perception operates across different levels of visual analysis, even at the highest levels of perceptual interpretation.

Calibration of the k- ɛ model constants for use in CFD applications

NASA Astrophysics Data System (ADS)

Glover, Nina; Guillias, Serge; Malki-Epshtein, Liora

2011-11-01

The k- ɛ turbulence model is a popular choice in CFD modelling due to its robust nature and the fact that it has been well validated. However it has been noted in previous research that the k- ɛ model has problems predicting flow separation as well as unconfined and transient flows. The model contains five empirical model constants whose values were found through data fitting for a wide range of flows (Launder 1972) but ad-hoc adjustments are often made to these values depending on the situation being modeled. Here we use the example of flow within a regular street canyon to perform a Bayesian calibration of the model constants against wind tunnel data. This allows us to assess the sensitivity of the CFD model to changes in these constants, find the most suitable values for the constants as well as quantifying the uncertainty related to the constants and the CFD model as a whole.

Anatomy of the sural nerve: cadaver study and literature review.

PubMed

Riedl, Otto; Frey, Manfred

2013-04-01

The sural nerve is commonly used as donor for nerve grafting. Contrary to its constant retromalleolar position, formation and course of the proximal sural nerve show great variability. The coexistence of different and deceptive terminologies contributes to the complexity, and reviewing the international literature is confusing. Because detailed anatomical knowledge is essential for efficient and safe sural nerve harvesting, this study aims to bring clarity. Previous sural nerve reports listed in the PubMed database and established anatomical textbooks were reviewed. Different terminologies were compared and adjusted. Anatomical details and variations were noted. Subtle prospective anatomical dissections and comparison with actual data followed. Two hundred twenty-one relevant reports were identified and worked up going back to the nineteenth century. Fourteen established German and English language anatomical textbooks were reviewed. Thirty lower limbs were dissected. In total, this study pools the information of more than 2500 sural nerves. This study covers all information about the sural nerve anatomy published internationally. The coexistence of different and confusing terminologies is pinpointed and adjusted to allow comparison of previous reports and to gain a coordinated data pool of more than 2500 investigated sural nerves. Detailed features are clearly described and summarized, findings from the authors' own prospective dissections complete these data, and the prior existing anatomical confusion is resolved. Finally, clinical implications are described.

Rare association between cystic fibrosis, Chiari I malformation, and hydrocephalus in a baby: a case report and review of the literature

PubMed Central

2011-01-01

Introduction Cystic fibrosis, an epithelial cell transport disorder caused by mutations of the cystic fibrosis transmembrane conductance regulator gene, is not generally associated with malformations of the central nervous system. We review eight previously published reports detailing an infrequent association between cystic fibrosis and Chiari I malformation. Case presentation To the best of our knowledge, our report describes only the ninth case of a baby presenting with a new diagnosis of cystic fibrosis and Chiari I malformation, in this case in a 10-month-old, full-term Caucasian baby boy from the United States of America. Neurosurgical consultation was obtained for associated developmental delay, macrocephaly, bulging anterior fontanel, and papilledema. An MRI scan demonstrated an extensive Chiari I malformation with effacement of the fourth ventricle, obliteration of the outlets of the fourth ventricle and triventricular hydrocephalus without aqueductal stenosis. Our patient was taken to the operating room for ventriculoperitoneal shunt placement. Conclusions It is possible that the cystic fibrosis transmembrane conductance regulator gene may play a previously unrecognized role in central nervous system development; alternatively, this central nervous system abnormality may have been acquired due to constant valsalva from recurrent coughing or wheezing or metabolic and electrolyte imbalances that occur characteristically in cystic fibrosis. PMID:21838874

Improving Models for Coseismic And Postseismic Deformation from the 2002 Denali, Alaska Earthquake

NASA Astrophysics Data System (ADS)

Harper, H.; Freymueller, J. T.

2016-12-01

Given the multi-decadal temporal scale of postseismic deformation, predictions of previous models for postseismic deformation resulting from the 2002 Denali Fault earthquake (M 7.9) do not agree with longer-term observations. In revising the past postseismic models with what is now over a decade of data, the first step is revisiting coseismic displacements and slip distribution of the earthquake. Advances in processing allow us to better constrain coseismic displacement estimates, which affect slip distribution predictions in modeling. Additionally, an updated slip model structure from a homogeneous model to a layered model rectifies previous inconsistencies between coseismic and postseismic models. Previous studies have shown that two primary processes contribute to postseismic deformation: afterslip, which decays with a short time constant; and viscoelastic relaxation, which decays with a longer time constant. We fit continuous postseismic GPS time series with three different relaxation models: 1) logarithmic decay + exponential decay, 2) log + exp + exp, and 3) log + log + exp. A grid search is used to minimize total model WRSS, and we find optimal relaxation times of: 1) 0.125 years (log) and 21.67 years (exp); 2) 0.14 years (log), 0.68 years (exp), and 28.33 years (exp); 3) 0.055 years (log), 14.44 years (log), and 22.22 years (exp). While there is not a one-to-one correspondence between a particular decay constant and a mechanism, the optimization of these constants allows us to model the future timeseries and constrain the contribution of different postseismic processes.

A modified proportional navigation scheme for rendezvous and docking with tumbling targets: The Planar case

NASA Technical Reports Server (NTRS)

Fitz-Coy, Norman; Liu, Ming-Cheng

1995-01-01

A two-phase proportional navigation scheme is developed for the case of two rigid bodies engaged in a rendezvous/docking maneuver. The target vehicle is nonmaneuvering, but does have constant nonzero angular and linear velocities. Under these conditions, it is shown that previously obtained solutions are not applicable. Analytical solutions are obtained leading to relationships between the transverse and LOS navigation constants. It is shown that the transverse navigation constant for the second phase of the maneuver must be 2. Also, initial conditions necessary for rendezvous are presented.

Reverse arthroplasty for osteoarthritis and rotator cuff deficiency after previous surgery for recurrent anterior shoulder instability.

PubMed

Raiss, Patric; Zeifang, Felix; Pons-Villanueva, Juan; Smithers, Christopher J; Loew, Markus; Walch, Gilles

2014-07-01

Osteoarthritis in combination with rotator cuff deficiency following previous shoulder stabilisation surgery and after failed surgical treatment for chronic anterior shoulder dislocation is a challenging condition. The aim of this study was to analyse the results of reverse shoulder arthroplasty in such patients. Thirteen patients with a median follow-up of 3.5 (range two to eight) years and a median age of 70 (range 48-82) years were included. In all shoulders a tear of at least one rotator cuff tendon in combination with osteoarthritis was present at the time of arthroplasty. The Constant score, shoulder flexion and external and internal rotation with the elbow at the side were documented pre-operatively and at the final follow-up. Pre-operative, immediate post-operative and final follow-up radiographs were analysed. All complications and revisions were documented. Twelve patients were either satisfied or very satisfied with the procedure. The median Constant score increased from 26 points pre-operatively to 67 points at the final follow-up (p = 0.001). The median shoulder flexion increased significantly from 70° to 130° and internal rotation from two to four points (p = 0.002). External rotation did not change significantly (p = 0.55). Glenoid notching was present in five cases and was graded as mild in three cases and moderate in two. One complication occurred leading to revision surgery. Reverse arthroplasty leads to high satisfaction rates for patients with osteoarthritis and rotator cuff deficiency who had undergone previous shoulder stabilisation procedures. The improvements in clinical outcome as well as the radiographic results seem to be comparable with those of other studies reporting on the outcome of reverse shoulder arthroplasty for other conditions.

Nuclear Proliferation Technology Trends Analysis

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

Zentner, Michael D.; Coles, Garill A.; Talbert, Robert J.

2005-10-04

A process is underway to develop mature, integrated methodologies to address nonproliferation issues. A variety of methodologies (both qualitative and quantitative) are being considered. All have one thing in common, a need for a consistent set of proliferation related data that can be used as a basis for application. One approach to providing a basis for predicting and evaluating future proliferation events is to understand past proliferation events, that is, the different paths that have actually been taken to acquire or attempt to acquire special nuclear material. In order to provide this information, this report describing previous material acquisition activitiesmore » (obtained from open source material) has been prepared. This report describes how, based on an evaluation of historical trends in nuclear technology development, conclusions can be reached concerning: (1) The length of time it takes to acquire a technology; (2) The length of time it takes for production of special nuclear material to begin; and (3) The type of approaches taken for acquiring the technology. In addition to examining time constants, the report is intended to provide information that could be used to support the use of the different non-proliferation analysis methodologies. Accordingly, each section includes: (1) Technology description; (2) Technology origin; (3) Basic theory; (4) Important components/materials; (5) Technology development; (6) Technological difficulties involved in use; (7) Changes/improvements in technology; (8) Countries that have used/attempted to use the technology; (9) Technology Information; (10) Acquisition approaches; (11) Time constants for technology development; and (12) Required Concurrent Technologies.« less

Optimal plane change during constant altitude hypersonic flight

NASA Technical Reports Server (NTRS)

Mease, K. D.; Vinh, N. X.; Kuo, S. H.

1988-01-01

Future spacecraft operating in the vicinity of the earth may have resort to the atmosphere as an aid in effecting orbital change. While a previous treatment of this technique chose constant altitude, speed, and angle-of-attack values in order to maximize the plane change for a fixed amount of propellant consumption during hypersonic flight, the former two parameters are presently released from the constraint of constancy. The general characteristics of the optimal controls are described on the basis of the domain of maneuverability, and numerical solutions are obtained for several specific cases. Under the condition of constant-altitude flight, it is generally not optimal to fly at constant angle-of-attack.

Computation of Kinetics for the Hydrogen/Oxygen System Using the Thermodynamic Method

NASA Technical Reports Server (NTRS)

Marek, C. John

1996-01-01

A new method for predicting chemical rate constants using thermodynamics has been applied to the hydrogen/oxygen system. This method is based on using the gradient of the Gibbs free energy and a single proportionality constant D to determine the kinetic rate constants. Using this method the rate constants for any gas phase reaction can be computed from thermodynamic properties. A modified reaction set for the H/O system is determined. A11 of the third body efficiencies M are taken to be unity. Good agreement was obtained between the thermodynamic method and the experimental shock tube data. In addition, the hydrogen bromide experimental data presented in previous work is recomputed with M's of unity.

Dynamic and Transient Performance of Turbofan/Turboshaft Convertible Engine With Variable Inlet Guide Vanes

NASA Technical Reports Server (NTRS)

McArdle, Jack G.; Barth, Richard L.; Wenzel, Leon M.; Biesiadny, Thomas J.

1996-01-01

A convertible engine called the CEST TF34, using the variable inlet guide vane method of power change, was tested on an outdoor stand at the NASA Lewis Research Center with a waterbrake dynamometer for the shaft load. A new digital electronic system, in conjunction with a modified standard TF34 hydromechanical fuel control, kept engine operation stable and safely within limits. All planned testing was completed successfully. Steady-state performance and acoustic characteristics were reported previously and are referenced. This report presents results of transient and dynamic tests. The transient tests measured engine response to several rapid changes in thrust and torque commands at constant fan (shaft) speed. Limited results from dynamic tests using the pseudorandom binary noise technique are also presented. Performance of the waterbrake dynamometer is discussed in an appendix.

[The cause of polyurethane catheter cracking during constant infusion of etoposide (VP-16) injection].

PubMed

Yokoyama, H; Aoyama, T; Matsuyama, T; Yamamura, Y; Nakajima, K; Nakamura, K; Sato, H; Kotaki, H; Chiba, S; Hirai, H; Yazaki, Y; Iga, T

1998-12-01

We studied the cause of cracking of a clinically used polyurethane (PU) catheter during the constant infusion of etoposide (VP-16) injection (Lastet), administered without dilution to patients as a part of combination high-dose chemotherapy. After VP-16 injection was infused into the PU catheter at a constant infusion rate (30 ml/h) for 24 h, a decrease in the elasticity (36% of untreated) and on increase in the length of the catheter (3.7%) were observed. These changes were significantly higher than those treated with the control saline. The similar changes of the PU catheter were observed after treatment with a basal solution containing polyethylene glycol 400 (PEG 400), polysorbate 80 and ethanol, which is the vehicle of the VP-16 injection, and with ethanol alone. Moreover, obvious degeneration of the internal wall (occurrence of spots like melting) and cutting face (micro-cracking) of the catheter was observed with an electron microscope after treatment with the vehicle. On the other hand, the elasticity or extension of the PU catheter were not changed after treatment with saline or PEG 400. From these findings, it was suggested that the degeneration and subsequent cracking of the PU catheter during the infusion of VP-16 injection was caused by ethanol contained in its injection solution. No cracking or morphological changes of polyvinyl chloride (PVC) and silicone catheters were found after treatment with the vehicle solution. However, since it has been reported in previous reports that di(2-ethylhexyl)phthalate was leached from PVC bags, the high dose chemotherapy with the dilution-free VP-16 injection should be achieved safely and effectively using a silicon catheter, rather than the PU catheter.

Calculation of nuclear spin-spin coupling constants using frozen density embedding

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

Götz, Andreas W., E-mail: agoetz@sdsc.edu; Autschbach, Jochen; Visscher, Lucas, E-mail: visscher@chem.vu.nl

2014-03-14

We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects inmore » the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.« less

O2(b1Σg+) Quenching by O2, CO2, H2O, and N2 at Temperatures of 300-800 K.

PubMed

Zagidullin, M V; Khvatov, N A; Medvedkov, I A; Tolstov, G I; Mebel, A M; Heaven, M C; Azyazov, V N

2017-10-05

Rate constants for the removal of O 2 (b 1 Σ g + ) by collisions with O 2 , N 2 , CO 2 , and H 2 O have been determined over the temperature range from 297 to 800 K. O 2 (b 1 Σ g + ) was excited by pulses from a tunable dye laser, and the deactivation kinetics were followed by observing the temporal behavior of the b 1 Σ g + -X 3 Σ g - fluorescence. The removal rate constants for CO 2 , N 2 , and H 2 O were not strongly dependent on temperature and could be represented by the expressions k CO2 = (1.18 ± 0.05) × 10 -17 × T 1.5 × exp[Formula: see text], k N2 = (8 ± 0.3) × 10 -20 × T 1.5 × exp[Formula: see text], and k H2O = (1.27 ± 0.08) × 10 -16 × T 1.5 × exp[Formula: see text] cm 3 molecule -1 s -1 . Rate constants for O 2 (b 1 Σ g + ) removal by O 2 (X), being orders of magnitude lower, demonstrated a sharp increase with temperature, represented by the fitted expression k O2 = (7.4 ± 0.8) × 10 -17 × T 0.5 × exp[Formula: see text] cm 3 molecule -1 s -1 . All of the rate constants measured at room temperature were found to be in good agreement with previously reported values.

Quasi-One-Dimensional Modeling of Pulse Detonation Rocket Engines

NASA Technical Reports Server (NTRS)

Morris, Christopher I.

2002-01-01

Pulsed detonation rocket engines (PDREs) have generated considerable research interest in recent years as a chemical propulsion system potentially offering improved performance and reduced complexity compared to conventional rocket engines. The detonative mode of combustion employed by these devices offers a thermodynamic advantage over the constant-pressure deflagrative combustion mode used in conventional rocket engines and gas turbines. However, while this theoretical advantage has spurred a great deal of interest in building PDRE devices, the unsteady blowdown process intrinsic to the PDRE has made realistic estimates of the actual propulsive performance problematic. The recent review article by Kailasanath highlights some of the difficulties in comparing the available experimental measurements with numerical models. In a previous paper by the author, parametric studies of the performance of a single, straight-tube PDRE were reported. A 1-D, unsteady method of characteristics code, employing a constant-gamma assumption behind the detonation front, was developed for that study. Models of this type are computationally inexpensive, and are particularly useful for parametric performance comparisons. For example, a plot showing the specific impulse of various PDRE and steady-state rocket engine (SSRE) configurations as a function of blowdown pressure ratio. The performance curves clearly indicate that a straight-tube PDRE is superior in specific impulse to a SSRE with a sonic nozzle over the entire range of pressure ratios. Note, however, that a straight-tube PDRE in general does not compare favorably to a SSRE fitted with an optimized de Laval supersonic nozzle, particularly at the high pressure ratios typical for boost or in-space rocket applications. However, the calculations also show that if a dynamically optimized, supersonic de Laval nozzle could be could be fitted to a PDRE, then the specific impulse of the device would exceed that of a comparable SSRE. While such a nozzle is a considerable idealization, it is clear that nozzle design and optimization will play a critical role in whether the performance potential of PDREs can be effectively realized in practice. In order to study PDRE nozzle issues with greater accuracy, a quasi-one-dimensional, finite-rate chemistry CFD code has been developed by the author. Comparisons of the code with both the previous MOC model and experimental data from Stanford University are reported. The effect of constant-gamma and finite-rate chemistry assumptions on the flowfield and performance is examined. Parametric studies of the effect of nozzle throat size and expansion ratio, at various blowdown pressure ratios, are reported.

The Effects of Constant versus Varied Reinforcers on Preference and Resistance to Change

ERIC Educational Resources Information Center

Milo, Jessie-Sue; Mace, F. Charles; Nevin, John A.

2010-01-01

Previous research has demonstrated that factors such as reinforcer frequency, amount, and delay have similar effects on resistance to change and preference. In the present study, 4 boys with autism made choices between a constant reinforcer (one that was the same food item every trial) and a varied food reinforcer (one that varied randomly between…

An Evaluation of Constant Time Delay and Simultaneous Prompting Procedures in Skill Acquisition for Young Children with Autism

ERIC Educational Resources Information Center

Brandt, Julie A. Ackerlund; Weinkauf, Sara; Zeug, Nicole; Klatt, Kevin P.

2016-01-01

Previous research has shown that various prompting procedures are effective in teaching skills to children and adults with developmental disabilities. Simultaneous prompting includes proving a prompt immediately following an instruction; whereas constant time-delay procedures include a set time delay (i.e., 5 s or 10 s) prior to delivering a…

Developmental times and life table statistics of Aulacorthum solani (Hemiptera: Aphididae) at six constant temperatures, with recommendations on the application of temperature-dependent development models

USDA-ARS?s Scientific Manuscript database

Developmental rates and age-specific life tables were determined for Aulacorthum solani (Kaltenbach) (known as foxglove aphid or glasshouse potato aphid) at 6 constant temperatures feeding on pansy (Viola × wittrockiana) (Gams.). Previously, there were no complete life table studies of this species...

Electron attachment to CF3 and CF3Br at temperatures up to 890 K: experimental test of the kinetic modeling approach.

PubMed

Shuman, Nicholas S; Miller, Thomas M; Viggiano, Albert A; Troe, Jürgen

2013-05-28

Thermal rate constants and product branching fractions for electron attachment to CF3Br and the CF3 radical have been measured over the temperature range 300-890 K, the upper limit being restricted by thermal decomposition of CF3Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF3Br measurement was made using standard techniques, and the CF3 measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF3Br proceeds exclusively by the dissociative channel yielding Br(-), with a rate constant increasing from 1.1 × 10(-8) cm(3) s(-1) at 300 K to 5.3 × 10(-8) cm(3) s(-1) at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF3 attachment proceeds through competition between associative attachment yielding CF3 (-) and dissociative attachment yielding F(-). Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only ~5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.

The eΠ3g state of C2: A pathway to dissociation

NASA Astrophysics Data System (ADS)

Welsh, B. A.; Krechkivska, O.; Nauta, K.; Bacskay, G. B.; Kable, S. H.; Schmidt, T. W.

2017-07-01

The lowest 13 vibrational levels, v = 0-12, of the eΠ3g state of the C2 molecule have been measured by laser-induced fluorescence of new bands of the Fox-Herzberg system. The newly observed levels, v = 5-12, which span the eΠ3g electronic state up to and beyond the first dissociation threshold of C2, were analyzed to afford highly accurate molecular constants, including band origins, and rotational and spin-orbit constants. The spin-orbit coupling constants of the previously published lowest five levels are revised in sign and magnitude, requiring an overhaul of previously published molecular constants. The analysis is supported by high level ab initio calculations. Lifetimes of all observed levels were recorded and found to be in excellent agreement with ab initio predicted values up to v = 11. v = 12 was found to exhibit a much reduced lifetime and fluorescence quantum yield, which is attributed to the onset of predissociation. This brackets the dissociation energy of ground state XΣ+1g C2 between 6.1803 and 6.2553 eV, in agreement with the Active Thermochemical Tables.

Bromamine Decomposition Revisited: A Holistic Approach for Analyzing Acid and Base Catalysis Kinetics.

PubMed

Wahman, David G; Speitel, Gerald E; Katz, Lynn E

2017-11-21

Chloramine chemistry is complex, with a variety of reactions occurring in series and parallel and many that are acid or base catalyzed, resulting in numerous rate constants. Bromide presence increases system complexity even further with possible bromamine and bromochloramine formation. Therefore, techniques for parameter estimation must address this complexity through thoughtful experimental design and robust data analysis approaches. The current research outlines a rational basis for constrained data fitting using Brønsted theory, application of the microscopic reversibility principle to reversible acid or base catalyzed reactions, and characterization of the relative significance of parallel reactions using fictive product tracking. This holistic approach was used on a comprehensive and well-documented data set for bromamine decomposition, allowing new interpretations of existing data by revealing that a previously published reaction scheme was not robust; it was not able to describe monobromamine or dibromamine decay outside of the conditions for which it was calibrated. The current research's simplified model (3 reactions, 17 constants) represented the experimental data better than the previously published model (4 reactions, 28 constants). A final model evaluation was conducted based on representative drinking water conditions to determine a minimal model (3 reactions, 8 constants) applicable for drinking water conditions.

The Temperature of Intracellular Ice Formation in Mouse Oocytes vs. the Unfrozen Fraction at that Temperature ⋆

PubMed Central

Mazur, Peter; Pinn, Irina L.; Kleinhans, F.W.

2009-01-01

We have previously reported [11] that intracellular ice formation (IIF) in mouse oocytes suspended in various concentrations of glycerol and ethylene glycol (EG) occurs at temperatures where the percentage of unfrozen water is about 6% and 12% respectively even though the IIF temperatures varied from −14° to −41°C. However, because of the way the solutions were prepared, the concentrations of salt and glycerol or EG in that unfrozen fraction at IIF were also rather tightly grouped. The experiments reported in the present paper were designed to separate the effects of the unfrozen fraction at IIF from that of the solute concentration in the unfrozen fraction. This separation makes use of two facts. One is that the concentration of solutes in the residual liquid at a given subzero temperature is fixed regardless of their concentration in the initial unfrozen solution. However, second, the fraction unfrozen at a given temperature is dependent on the initial solute concentration. Experimentally, oocytes were suspended in solutions of glycerol/buffered saline and EG/buffered saline of varying total solute concentration with the restriction that the mass ratio of glycerol and EG to salts are held constant. The oocytes were then cooled rapidly enough (20°C/min) to avoid significant osmotic shrinkage, and the temperature at which IIF occurred as noted. When this is done, we find, as previously that the fraction of water remaining unfrozen at the temperature of IIF remains nearly constant at 5 to 8% for both glycerol and EG even though the IIF temperatures vary from −14°C to −50°C. But unlike the previous results, the salt and CPA concentrations in the unfrozen fraction vary by a factor of three. The present procedure for preparing the solutions produces a potentially complicating factor; namely, the cell volumes vary substantially prior to freezing: Substantially greater than isotonic in some solution; substantially smaller in others. However, the data in toto demonstrate that cell volume is not a determining factor in the IIF temperature. PMID:17379206

The temperature of intracellular ice formation in mouse oocytes vs. the unfrozen fraction at that temperature.

PubMed

Mazur, Peter; Pinn, Irina L; Kleinhans, F W

2007-04-01

We have previously reported [Cryobiology 51 (2005) 29-53] that intracellular ice formation (IIF) in mouse oocytes suspended in various concentrations of glycerol and ethylene glycol (EG) occurs at temperatures where the percentage of unfrozen water is about 6% and 12%, respectively, even though the IIF temperatures varied from -14 to -41 degrees C. However, because of the way the solutions were prepared, the concentrations of salt and glycerol or EG in that unfrozen fraction at IIF were also rather tightly grouped. The experiments reported in the present paper were designed to separate the effects of the unfrozen fraction at IIF from that of the solute concentration in the unfrozen fraction. This separation makes use of two facts. One is that the concentration of solutes in the residual liquid at a given subzero temperature is fixed regardless of their concentration in the initial unfrozen solution. However, second, the fraction unfrozen at a given temperature is dependent on the initial solute concentration. Experimentally, oocytes were suspended in solutions of glycerol/buffered saline and EG/buffered saline of varying total solute concentration with the restriction that the mass ratios of glycerol and EG to salts are held constant. The oocytes were then cooled rapidly enough (20 degrees C/min) to avoid significant osmotic shrinkage, and the temperature at which IIF occurred was noted. When this is done, we find, as previously that the fraction of water remaining unfrozen at the temperature of IIF remains nearly constant at 5-8% for both glycerol and EG even though the IIF temperatures vary from -14 to -50 degrees C. But unlike the previous results, the salt and CPA concentrations in the unfrozen fraction vary by a factor of three. The present procedure for preparing the solutions produces a potentially complicating factor; namely, the cell volumes vary substantially prior to freezing: substantially greater than isotonic in some solutions; substantially smaller in others. However, the data in toto demonstrate that cell volume is not a determining factor in the IIF temperature.

A Predictive Model Has Identified Tick-Borne Encephalitis High-Risk Areas in Regions Where No Cases Were Reported Previously, Poland, 1999–2012

PubMed Central

Rubikowska, Barbara; Bratkowski, Jakub; Ustrnul, Zbigniew; Vanwambeke, Sophie O.

2018-01-01

During 1999–2012, 77% of the cases of tick-borne encephalitis (TBE) were recorded in two out of 16 Polish provinces. However, historical data, mostly from national serosurveys, suggest that the disease could be undetected in many areas. The aim of this study was to identify which routinely-measured meteorological, environmental, and socio-economic factors are associated to TBE human risk across Poland, with a particular focus on areas reporting few cases, but where serosurveys suggest higher incidence. We fitted a zero-inflated Poisson model using data on TBE incidence recorded in 108 NUTS-5 administrative units in high-risk areas over the period 1999–2012. Subsequently we applied the best fitting model to all Polish municipalities. Keeping the remaining variables constant, the predicted rate increased with the increase of air temperature over the previous 10–20 days, precipitation over the previous 20–30 days, in forestation, forest edge density, forest road density, and unemployment. The predicted rate decreased with increasing distance from forests. The map of predicted rates was consistent with the established risk areas. It predicted, however, high rates in provinces considered TBE-free. We recommend raising awareness among physicians working in the predicted high-risk areas and considering routine use of household animal surveys for risk mapping. PMID:29617333

A Predictive Model Has Identified Tick-Borne Encephalitis High-Risk Areas in Regions Where No Cases Were Reported Previously, Poland, 1999-2012.

PubMed

Stefanoff, Pawel; Rubikowska, Barbara; Bratkowski, Jakub; Ustrnul, Zbigniew; Vanwambeke, Sophie O; Rosinska, Magdalena

2018-04-04

During 1999–2012, 77% of the cases of tick-borne encephalitis (TBE) were recorded in two out of 16 Polish provinces. However, historical data, mostly from national serosurveys, suggest that the disease could be undetected in many areas. The aim of this study was to identify which routinely-measured meteorological, environmental, and socio-economic factors are associated to TBE human risk across Poland, with a particular focus on areas reporting few cases, but where serosurveys suggest higher incidence. We fitted a zero-inflated Poisson model using data on TBE incidence recorded in 108 NUTS-5 administrative units in high-risk areas over the period 1999–2012. Subsequently we applied the best fitting model to all Polish municipalities. Keeping the remaining variables constant, the predicted rate increased with the increase of air temperature over the previous 10–20 days, precipitation over the previous 20–30 days, in forestation, forest edge density, forest road density, and unemployment. The predicted rate decreased with increasing distance from forests. The map of predicted rates was consistent with the established risk areas. It predicted, however, high rates in provinces considered TBE-free. We recommend raising awareness among physicians working in the predicted high-risk areas and considering routine use of household animal surveys for risk mapping.

A new approach using coagulation rate constant for evaluation of turbidity removal

NASA Astrophysics Data System (ADS)

Al-Sameraiy, Mukheled

2017-06-01

Coagulation-flocculation-sedimentation processes for treating three levels of bentonite synthetic turbid water using date seeds (DS) and alum (A) coagulants were investigated in the previous research work. In the current research, the same experimental results were used to adopt a new approach on a basis of using coagulation rate constant as an investigating parameter to identify optimum doses of these coagulants. Moreover, the performance of these coagulants to meet (WHO) turbidity standard was assessed by introducing a new evaluating criterion in terms of critical coagulation rate constant (kc). Coagulation rate constants (k2) were mathematically calculated in second order form of coagulation process for each coagulant. The maximum (k2) values corresponded to doses, which were obviously to be considered as optimum doses. The proposed criterion to assess the performance of coagulation process of these coagulants was based on the mathematical representation of (WHO) turbidity guidelines in second order form of coagulation process stated that (k2) for each coagulant should be ≥ (kc) for each level of synthetic turbid water. For all tested turbid water, DS coagulant could not satisfy it. While, A coagulant could satisfy it. The results obtained in the present research are exactly in agreement with the previous published results in terms of finding optimum doses for each coagulant and assessing their performances. On the whole, it is recommended considering coagulation rate constant to be a new approach as an indicator for investigating optimum doses and critical coagulation rate constant to be a new evaluating criterion to assess coagulants' performance.

Blastomycosis in the mountainous region of northeast Tennessee.

PubMed

Hussein, Rezhan; Khan, Saad; Levy, Foster; Mehta, Jay B; Sarubbi, Felix A

2009-04-01

In the United States, cases of human blastomycosis are largely described in defined geographic areas, with Mississippi reporting the highest prevalence of disease in the southeast region. The infection is uncommonly recognized in mountainous areas, and our previous report of blastomycosis in the southern Appalachian mountains of northeast Tennessee appeared to be an exception to the usual disease distribution. Our current retrospective study was undertaken to determine whether blastomycosis has persisted as an endemic fungal infection in our northeast Tennessee geographic area and whether epidemiologic features have changed over a 25-year time period. Results show that clinical aspects of the disease have remained fairly constant with few exceptions; mass-type pulmonary lesions have become more common, and itraconazole has emerged as the therapy of choice. Most notably, however, are the observations that blastomycosis persists as a major endemic fungal infection in our mountain region, more than half of all cases occurring during the period from 1996 to 2005 were found in a core area centered on two counties, Washington and Unicoi; three of five counties surrounding the core counties experienced rate increases compared to our previous study. These findings suggest a further expansion of this endemic fungal disease beyond the core region.

Role of Hydrogen Bonding in Photoinduced Electron-Proton Transfer from Phenols to a Polypyridine Ru Complex with a Proton-Accepting Ligand

DOE PAGES

Lymar, Sergei V.; Ertem, Mehmed Z.; Lewandowska-Andralojc, Anna; ...

2017-08-09

Electron-proton transfer, EPT, from phenols to a triplet MLCT-excited Ru polypyridine complex containing an uncoordinated nitrogen site, 1(T), can be described by a kinetic model that accounts for the H-bonding of 1(T) to phenol, 1(T) to solvent, and phenol to solvent. The latter plays a major role in the kinetic solvent effect and commonly precludes simultaneous determination of the EPT rate constant and 1(T)-phenol H-bonding constant. A number of these quantities previously reported for similar systems are shown to be in error due to an inconsistent data analysis. In conclusion, control experiments replacing either 1(T) by its structural isomer withmore » a sterically screened nitrogen site or phenol by its H-bonding surrogate, trifluoroethanol, and the observation of negative activation enthalpies for the overall reactions between 1(T) and phenols lend support to the proposed model and provide evidence for the formation of a precursor H-bonded complex between the reactants, which is a prerequisite for EPT.« less

Role of Hydrogen Bonding in Photoinduced Electron-Proton Transfer from Phenols to a Polypyridine Ru Complex with a Proton-Accepting Ligand

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

Lymar, Sergei V.; Ertem, Mehmed Z.; Lewandowska-Andralojc, Anna

Electron-proton transfer, EPT, from phenols to a triplet MLCT-excited Ru polypyridine complex containing an uncoordinated nitrogen site, 1(T), can be described by a kinetic model that accounts for the H-bonding of 1(T) to phenol, 1(T) to solvent, and phenol to solvent. The latter plays a major role in the kinetic solvent effect and commonly precludes simultaneous determination of the EPT rate constant and 1(T)-phenol H-bonding constant. A number of these quantities previously reported for similar systems are shown to be in error due to an inconsistent data analysis. In conclusion, control experiments replacing either 1(T) by its structural isomer withmore » a sterically screened nitrogen site or phenol by its H-bonding surrogate, trifluoroethanol, and the observation of negative activation enthalpies for the overall reactions between 1(T) and phenols lend support to the proposed model and provide evidence for the formation of a precursor H-bonded complex between the reactants, which is a prerequisite for EPT.« less

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

Dang, Liem X.; Vo, Quynh N.; Nilsson, Mikael

We report one of the first simulations using a classical rate theory approach to predict the mechanism of the exchange process between water and aqueous uranyl ions. Using our water and ion-water polarizable force fields and molecular dynamics techniques, we computed the potentials of mean force for the uranyl ion-water pair as the function of pressures at ambient temperature. Subsequently, these simulated potentials of mean force were used to calculate rate constants using the transition rate theory; the time dependent transmission coefficients were also examined using the reactive flux method and Grote-Hynes treatments of the dynamic response of the solvent.more » The computed activation volumes using transition rate theory and the corrected rate constants are positive, thus the mechanism of this particular water-exchange is a dissociative process. We discuss our rate theory results and compare them with previously studies in which non-polarizable force fields were used. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.« less

O-ribosyl-phosphate purine as a constant modified nucleotide located at position 64 in cytoplasmic initiator tRNAs(Met) of yeasts.

PubMed Central

Glasser, A L; Desgres, J; Heitzler, J; Gehrke, C W; Keith, G

1991-01-01

The unknown modified nucleotide G*, isolated from both Schizosaccharomyces pombe and Torulopsis utilis initiator tRNAs(Met), has been identified as an O-ribosyl-(1"----2')-guanosine-5"-phosphate, called Gr(p), by means of HPLC, UV-absorption, mass spectrometry and periodate oxidation procedures. By comparison with the previously published structure of Ar(p) isolated from Saccharomyces cerevisiae initiator tRNA(Met), the (1"----2')-glycosidic bond in Gr(p) has been postulated to have a beta-spatial conformation. The modified nucleotide Gr(p) is located at position 64 in the tRNA(Met) molecules, i.e. at the same position as Ar(p). Since we have also characterized Gr(p) in Candida albicans initiator tRNA(Met), the phosphoribosylation of purine 64 can be considered as a constant nucleotide modification in the cytoplasmic initiator tRNAs(Met) of all yeast species so far sequenced. Precise evidence for the presence of Gr(p) in initiator tRNAs(Met) of several plants is also reported. PMID:1656390

Revisiting PbTe to identify how thermal conductivity is really limited

NASA Astrophysics Data System (ADS)

Ju, Shenghong; Shiga, Takuma; Feng, Lei; Shiomi, Junichiro

2018-05-01

Due to the long range interaction in lead telluride (PbTe), the transverse optical (TO) phonon becomes soft around the Brillouin zone center. Previous studies have postulated that this zone-center softening causes the low thermal conductivity of PbTe through either enlarged phonon scattering phase space and/or strengthened lattice anharmonicity. In this paper, we reported an extensive sensitivity analysis of the PbTe thermal conductivity to various factors: range and magnitude of harmonic and anharmonic interatomic force constants and phonon wave vectors in the three-phonon scattering processes. The analysis reveals that the softening by long range harmonic interaction itself does not reduce thermal conductivity, and it is the large magnitude of the anharmonic (cubic) force constants that realizes low thermal conductivity, however, not through the TO phonons around the zone center but dominantly through the ones with larger wave vectors in the middle of Brillion zone. The paper clarifies that local band softening cannot be a direct finger print for low thermal conductivity and that the entire Brillion zone needs to be characterized on exploring low thermal conductivity materials.

The Thermochemical and Kinetic Properties of Ascorbate are Tuned by its Local Environment: Solution Chemistry and Biochemical Implications

PubMed Central

Warren, Jeffrey J.; Mayer, James M.

2010-01-01

Ascorbate (Vitamin C) is a ubiquitous biological cofactor. While its aqueous solution chemistry has long been studied, many in vivo reactions of ascorbate occur in enzyme active sites or at membrane interfaces, which have varying local environments. This report shows that the rate and driving force of oxidations of two ascorbate derivatives by the TEMPO radical (2,2′-6,6′-tetramethylpiperidine-1-oxyl) in acetonitrile are very sensitive to the presence of various additives. These reactions proceed by the transfer of a proton and an electron (a hydrogen atom), as is typical of biological ascorbate reactions. The measured rate and equilibrium constants vary substantially with added water or other polar solutes in acetonitrile solutions, indicating large shifts in the reducing power of ascorbate. The correlation of rate and equilibrium constants indicates that this effect has a thermochemical origin rather than being a purely kinetic effect. This contrasts with previous examples of solvent effects on hydrogen atom transfer reactions. Potential biological implications of this apparently unique effect are discussed. PMID:20476757

Theory of long binding events in single-molecule–controlled rotation experiments on F1-ATPase

PubMed Central

Volkán-Kacsó, Sándor; Marcus, Rudolph A.

2017-01-01

The theory of elastic group transfer for the binding and release rate constants for nucleotides in F1-ATPase as a function of the rotor angle is further extended in several respects. (i) A method is described for predicting the experimentally observed lifetime distribution of long binding events in the controlled rotation experiments by taking into account the hydrolysis and synthesis reactions occurring during these events. (ii) A method is also given for treating the long binding events in the experiments and obtaining the rate constants for the hydrolysis and synthesis reactions occurring during these events. (iii) The theory in the previous paper is given in a symmetric form, an extension that simplifies the application of the theory to experiments. It also includes a theory-based correction of the reported “on” and “off” rates by calculating the missed events. A near symmetry of the data about the angle of −40° and a “turnover” in the binding rate data vs. rotor angle for angles greater than ∼40° is also discussed. PMID:28652332

Morin Flavonoid Adsorbed on Mesoporous Silica, a Novel Antioxidant Nanomaterial

PubMed Central

Arriagada, Francisco; Correa, Olosmira; Günther, Germán; Nonell, Santi; Mura, Francisco; Olea-Azar, Claudio

2016-01-01

Morin (2´,3, 4´,5,7-pentahydroxyflavone) is a flavonoid with several beneficial health effects. However, its poor water solubility and it sensitivity to several environmental factors avoid its use in applications like pharmaceutical and cosmetic. In this work, we synthetized morin-modified mesoporous silica nanoparticles (AMSNPs-MOR) as useful material to be used as potential nanoantioxidant. To achieve this, we characterized its adsorption kinetics, isotherm and the antioxidant capacity as hydroxyl radical (HO•) scavenger and singlet oxygen (1O2) quencher. The experimental data could be well fitted with Langmuir, Freundlich and Temkin isotherm models, besides the pseudo-second order kinetics model. The total quenching rate constant obtained for singlet oxygen deactivation by AMSNPs-MOR was one order of magnitude lower than the morin rate constant reported previously in neat solvents and lipid membranes. The AMSNPs-MOR have good antioxidant properties by itself and exhibit a synergic effect with morin on the antioxidant property against hydroxyl radical. This effect, in the range of concentrations studied, was increased when the amount of morin adsorbed increased. PMID:27812111

Density functional theory study of structural, electronic, and thermal properties of Pt, Pd, Rh, Ir, Os and PtPd X (X = Ir, Os, and Rh) alloys

NASA Astrophysics Data System (ADS)

Shabbir, Ahmed; Muhammad, Zafar; M, Shakil; M, A. Choudhary

2016-03-01

The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys PtPdX (X = Ir, Os and Rh) are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties. We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.

The melting temperature of liquid water with the effective fragment potential

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

Brorsen, Kurt R.; Willow, Soohaeng Y.; Xantheas, Sotiris S.

2015-09-17

Direct simulation of the solid-liquid water interface with the effective fragment potential (EFP) via the constant enthalpy and pressure (NPH) ensemble was used to estimate the melting temperature (Tm) of ice-Ih. Initial configurations and velocities, taken from equilibrated constant pressure and temperature (NPT) simulations at T = 300 K, 350 K and 400 K, respectively, yielded corresponding Tm values of 378±16 K, 382±14 K and 384±15 K. These estimates are consistently higher than experiment, albeit to the same degree with previously reported estimates using density functional theory (DFT)-based Born-Oppenheimer simulations with the Becke-Lee-Yang-Parr functional plus dispersion corrections (BLYP-D). KRB wasmore » supported by a Computational Science Graduate Fellowship from the Department of Energy. MSG was supported by a U.S. National Science Foundation Software Infrastructure (SI2) grant (ACI – 1047772). SSX acknowledges support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.« less

First High Resolution IR Study of the νb{14} (a') A-Type Band Near 421.847 \\wn of 2-^{13}C-PROPENE

NASA Astrophysics Data System (ADS)

Daunt, S. J.; Grzywacz, Robert; Billinghurst, Brant E.

2017-06-01

This is is the first high resolution IR study of any band of the 2-^{13}C-propene species. There have been only two previous high resolution studies of vibration-rotation bands of the normal species. The band examined here is the νb{14} (A') CCC skeletal bending near 421.847 \\wn which has an A-Type asymmetric rotor structure. The spectra were recorded on the FTS at the Far-IR beamline of the Canadian Light Source with a resolution of Δν = 0.0009 \\wn. We have assigned and fitted around 2200 transitions and determined ground and upper state rotational constants. Lines with J up to 49 and K up to 12 were included. The subbands with K greater than 12 were perturbed and show torsional splittings that vary from small to extremely large. The fitting was done with the PGOPHER program of Colin Western. The GS constants are in good agreement with the MW constants reported recently by Craig, Groner and co-workers. Ainetschian, Fraser, Ortigoso & Pate, J. Chem. Phys. 100, 729 ff. (1994); Lafferty, Flaud & Herman, J. Mol. Struct. 780-781, 65 ff. (2006). Western, J. Quant. Spectrosc. Rad. Transf. 186, 221 ff. (2017). Paper M109, 71st ISMS Symposium (2016); J. Mol. Spectrosc. 328, 1-6 (2016).

Electronic spectrum of jet cooled SiCN

NASA Astrophysics Data System (ADS)

Fukushima, Masaru; Ishiwata, Takashi

2016-09-01

We have generated SiCN in a supersonic free expansion, and measured the laser induced fluorescence (LIF) spectrum. Prior to the experiments, ab initio calculations were carried out to obtain the information necessary for searching for the LIF signals. In addition to the X ˜ 2Π state, the optimized structures of three excited states, 2Δ, 2Σ+, and 2Σ-, have been obtained. Guided by the predictions, the LIF excitation spectrum of SiCN was observed in the UV region. The rotational structure of the 00 0 band with the origin, 29 261.639 cm-1, indicated that the electronic transition is A ˜ 2Δ- X ˜ 2Π. The spin-orbit (SO) constants of the X ˜ 2Π and A ˜ 2Δ states were determined to be 140.824 and 4.944 cm-1, respectively. In the A ˜ 2Δ state, the Fermi resonance between the (0, 20, 0) 2Δ and (0, 00, 1) 2Δ vibronic levels was identified. The molecular constants of the X ˜ 2Π state were determined through the simultaneous analysis of the combination differences derived from the present LIF data with the previously reported rotational transitions. The spectroscopic parameters of the A ˜ 2Δ state were also obtained from the analysis where the constants of the X ˜ 2Π state, derived above, were fixed at those values.

Single crystal substrates for surface acoustic wave devices

NASA Astrophysics Data System (ADS)

Barsch, G. R.; Spear, K. E.

1981-01-01

In order to search for new temperature compensated materials for surface acoustic wave (SAW) devices with low ultrasonic attenuation and high electromechanical coupling, the following experimental and theoretical investigations were carried out: (1) Crystal growth research centered around: designing, constructing, and writing the software for a computer controlled constant-diameter attachment for our Czochralski crystal pullers; a major experimental effort on the growth of lead potassium niobate (PKN); Pb2KNb5O15, and lead bismuth niobate (PBN) PbBi2Nb2O9, and a minor experimental effort on the growth of lithium metasilicate, Li2SiO3; and bismuth molybdate, Bi2MoO6. (2) The dielectric constants and the associated loss tangents of alpha-berlinite were measured at eleven frequencies from 100 to 10,000 Hz between -150 and 200 C. The temperature dependence of the dielectric constants and the relaxation behavior are similar to the results obtained earlier, but the absolute values are 20 to 30 percent smaller than reported previously. (3) The temperature dependence of the two shear modes propagating in (001) has been measured from 10 to 315K for Bi4Ti3O12. A monotonical decrease of the associated shear moduli has been found. (4) Considerable effort was devoted to specimen preparation of lead bismuth niobate which was hampered by the easy cleavage of this material perpendicular to 001 .

Fabrication of one-dimensional alumina photonic crystals by anodization using a modified pulse-voltage method

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

Li, Shou-Yi; Wang, Jian, E-mail: wangjian@nwnu.edu.cn; Wang, Gang

2015-08-15

Highlights: • The alumina multilayer structure with alternating high and low refractive index is fabricated. • This multilayer shows a strong photonic band gap (PBG) and vivid film colors. • The first PBG could be modulated easily by varying the duration time of constant high or low voltages. • Fabrication of the photonic crystal is obtained by directly electrochemical anodization. • The formation mechanism of multilayer is also discussed. - Abstract: The alumina nanolayer structure with alternating high and low porosities is conveniently fabricated by applying a modified pulse voltage waveform with constant high and low voltage. This structure showsmore » the well-defined layer in a long-range structural periodicity leads to a strong photonic band gap (PBG) from visible to near infrared and brilliant film colors. Compared with the previous reported tuning method, this method is more simple and flexible in tuning the PBG of photonic crystals (PCs). The effect of duration time of high, low and 0 V voltages on PBG is discussed. The first PBG could be modulated easily from the visible to near infrared region by varying the duration time of constant high or low voltages. It is also found that the 0 V lasting for appropriate time is helpful to improve the quality of the PCs. The formation mechanism of multilayer is also discussed.« less

Wireless local area networking for linking a PC reporting system and PACS: clinical feasibility in emergency reporting.

PubMed

Yoshihiro, Akiko; Nakata, Norio; Harada, Junta; Tada, Shimpei

2002-01-01

Although local area networks (LANs) are commonplace in hospital-based radiology departments today, wireless LANs are still relatively unknown and untried. A linked wireless reporting system was developed to improve work throughput and efficiency. It allows radiologists, physicians, and technologists to review current radiology reports and images and instantly compare them with reports and images from previous examinations. This reporting system also facilitates creation of teaching files quickly, easily, and accurately. It consists of a Digital Imaging and Communications in Medicine 3.0-based picture archiving and communication system (PACS), a diagnostic report server, and portable laptop computers. The PACS interfaces with magnetic resonance imagers, computed tomographic scanners, and computed radiography equipment. The same kind of functionality is achievable with a wireless LAN as with a wired LAN, with comparable bandwidth but with less cabling infrastructure required. This wireless system is presently incorporated into the operations of the emergency and radiology departments, with future plans calling for applications in operating rooms, outpatient departments, all hospital wards, and intensive care units. No major problems have been encountered with the system, which is in constant use and appears to be quite successful. Copyright RSNA, 2002

On parasupersymmetric oscillators and relativistic vector mesons in constant magnetic fields

NASA Technical Reports Server (NTRS)

Debergh, Nathalie; Beckers, Jules

1995-01-01

Johnson-Lippmann considerations on oscillators and their connection with the minimal coupling schemes are visited in order to introduce a new Sakata-Taketani equation describing vector mesons in interaction with a constant magnetic field. This new proposal, based on a specific parasupersymmetric oscillator-like system, is characterized by real energies as opposed to previously pointed out relativistic equations corresponding to this interacting context.

Hyperfine structure measurements of neutral vanadium by laser-induced fluorescence spectroscopy in the wavelength range from 750 nm to 860 nm

NASA Astrophysics Data System (ADS)

Başar, Gü.; Güzelçimen, F.; Öztürk, I. K.; Er, A.; Bingöl, D.; Kröger, S.; Başar, Gö.

2017-11-01

The hyperfine structure of 57 spectral lines of neutral vanadium has been investigated using a hollow cathode lamp by laser-induced fluorescence spectroscopy in the wavelength range from 750 nm to 860 nm. New magnetic dipole hyperfine structure constants A have been determined for 14 atomic energy levels and new electric quadrupole hyperfine structure constants B for two levels. Additionally previously published hyperfine structure constants A of 56 levels have been measured again. In five cases, the old A values have been rejected and replaced by improved values.

Use of polynomial expressions to describe the bioconcentration of hydrophobic chemicals by fish

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

Connell, D.W.; Hawker, D.W.

1988-12-01

For the bioconcentration of hydrophobic chemicals by fish, relationships have been previously established between uptake rate constants (k1) and the octanol/water partition coefficient (Kow), and also between the clearance rate constant (k2) and Kow. These have been refined and extended on the basis of data for chlorinated hydrocarbons, and closely related compounds including polychlorinated dibenzodioxins, that covered a wider range of hydrophobicity (2.5 less than log Kow less than 9.5). This has allowed the development of new relationships between log Kow and various factors, including the bioconcentration factor (as log KB), equilibrium time (as log teq), and maximum biotic concentrationmore » (as log CB), which include extremely hydrophobic compounds previously not taken into account. The shape of the curves generated by these equations are in qualitative agreement with theoretical prediction and are described by polynomial expressions which are generally approximately linear over the more limited range of log Kow values used to develop previous relationships. The influences of factors such as hydrophobicity, aqueous solubility, molecular weight, lipid solubility, and also exposure time were considered. Decreasing lipid solubilities of extremely hydrophobic chemicals were found to result in increasing clearance rate constants, as well decreasing equilibrium times and bioconcentration factors.« less

A New "Quasi-Dynamic" Method for Determining the Hamaker Constant of Solids Using an Atomic Force Microscope.

PubMed

Fronczak, Sean G; Dong, Jiannan; Browne, Christopher A; Krenek, Elizabeth C; Franses, Elias I; Beaudoin, Stephen P; Corti, David S

2017-01-24

In order to minimize the effects of surface roughness and deformation, a new method for estimating the Hamaker constant, A, of solids using the approach-to-contact regime of an atomic force microscope (AFM) is presented. First, a previous "jump-into-contact" quasi-static method for determining A from AFM measurements is analyzed and then extended to include various AFM tip-surface force models of interest. Then, to test the efficacy of the "jump-into-contact" method, a dynamic model of the AFM tip motion is developed. For finite AFM cantilever-surface approach speeds, a true "jump" point, or limit of stability, is found not to appear, and the quasi-static model fails to represent the dynamic tip behavior at close tip-surface separations. Hence, a new "quasi-dynamic" method for estimating A is proposed that uses the dynamically well-defined deflection at which the tip and surface first come into contact, d c , instead of the dynamically ill-defined "jump" point. With the new method, an apparent Hamaker constant, A app , is calculated from d c and a corresponding quasi-static-based equation. Since A app depends on the cantilever's approach speed, v c , and the AFM's sampling resolution, δ, a double extrapolation procedure is used to determine A app in the quasi-static (v c → 0) and continuous sampling (δ → 0) limits, thereby recovering the "true" value of A. The accuracy of the new method is validated using simulated AFM data. To enable the experimental implementation of this method, a new dimensionless parameter τ is introduced to guide cantilever selection and the AFM operating conditions. The value of τ quantifies how close a given cantilever is to its quasi-static limit for a chosen cantilever-surface approach speed. For sufficiently small values of τ (i.e., a cantilever that effectively behaves "quasi-statically"), simulated data indicate that A app will be within ∼3% or less of the inputted value of the Hamaker constant. This implies that Hamaker constants can be reliably estimated using a single measurement taken with an appropriately chosen cantilever and a slow, yet practical, approach speed (with no extrapolation required). This result is confirmed by the very good agreement found between the experimental AFM results obtained using this new method and previously reported predictions of A for amorphous silica, polystyrene, and α-Al 2 O 3 substrates obtained using the Lifshitz method.

Kinetics of cyclopentene isomerization at 1200 K

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

Lewis, D.K.; Baldwin, J.E.; Cianciosi, S.J.

1990-09-20

This study was conducted to determine the rate of intramolecular degenerate rearrangement of cyclopentene (CP), presumably via reversible conversion to vinylcyclopropane (VCP). Cyclopentene-3-{sup 13}C was synthesized and heated to 1,200 K in a single-pulse shock tube and then analyzed by {sup 13}C NMR to ascertain the extent of migration of the {sup 13}C label to the 4-position. The very small amounts of migration observed were consistent with log k(CP {yields} VCP) = 15.7 {minus} (16,000/T). This rate constant for CP {yields} VCP is too small to account for the previously reported evidence of multiple channels for H{sub 2} elimination frommore » CP.« less

Difluoro-and Trifluoromethylation of Electron-Deficient Alkenes in an Electrochemical Microreactor.

PubMed

Arai, Kenta; Watts, Kevin; Wirth, Thomas

2014-02-01

Electrochemical microreactors, which have electrodes integrated into the flow path, can afford rapid and efficient electrochemical reactions without redox reagents due to the intrinsic properties of short diffusion distances. Taking advantage of electrochemical microreactors, Kolbe electrolysis of di-and trifluoroacetic acid in the presence of various electron-deficient alkenes was performed under constant current at continuous flow at room temperature. As a result, di-and trifluoromethylated compounds were effectively produced in either equal or higher yields than identical reactions under batch conditions previously reported by Uneyamas group. The strategy of using electrochemical microreactor technology is useful for an effective fluoromethylation of alkenes based on Kolbe electrolysis in significantly shortened reaction times.

Control of hypertension with single daily doses of sotalol hydrochloride.

PubMed

Gabriel, R

A study was carried out in 12 previously untreated hypertensive patients to assess the efficacy of sotalol given in a once-daily dosage regimen. After an initial dosage titration period (mean 3 weeks) during which diastolic pressure was stabilized at less than 100 mmHg, all patients were satisfactorily maintained on a constant once-daily dose of sotalol for 3 months. Eight of the 12 patients required 320 mg or less daily (mean dose 190 mg). Whilst blood pressure remained controlled for at least 26 hours after daily doses the pulse rate, counted at the same time, showed escape from beta-blockade. Side-effects (vivid dreams) were reported in only 1 patient.

Experimental Study of Heat Transfer to Small Cylinders in a Subsonic, High-temperature Gas Stream

NASA Technical Reports Server (NTRS)

Glawe, George E; Johnson, Robert C

1957-01-01

A Nusselt-Reynolds number relation for cylindrical thermocouple wires in crossflow was obtained from the experimental determination of time constants. Tests were conducted in exhaust gas over a temperature range of 2000 to 3400 R, a Mach number range of 0.3 to 0.8, and a static-pressure range from 2/3 to 1-1/3 atmospheres, yielding a Reynolds number range of 450 to 3000. The correlation obtained is Nu=(0.428 plus or minus 0.003) times the square root of Re* with average deviations of a single observation of 8.5 percent. This relation is the same as one previously reported for room-temperature conditions.

Kinetics studies of rapid strain-promoted [3 + 2]-cycloadditions of nitrones with biaryl-aza-cyclooctynone.

PubMed

McKay, Craig S; Chigrinova, Mariya; Blake, Jessie A; Pezacki, John Paul

2012-04-21

Strain-promoted cycloadditions of cyclic nitrones with biaryl-aza-cyclooctynone (BARAC) proceed with rate constants up to 47.3 M(-1) s(-1), this corresponds to a 47-fold rate enhancement relative to reaction of BARAC with benzyl azide and a 14-fold enhancement over previously reported strain promoted alkyne-nitrone cycloadditions (SPANC). Studies of the SPANC reaction using the linear free energy relationship defined by the Hammett equation demonstrated that the cycloaddition reaction has a rho value of 0.25 ± 0.04, indicating that reaction is not sensitive to substituents and thus should have broad applicability. This journal is © The Royal Society of Chemistry 2012

A study of the conformational isomerism of 1-iodobutane by high resolution rotational spectroscopy

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

Arsenault, Eric A.; Obenchain, Daniel A.; Blake, Thomas A.

2017-05-01

The first microwave study of 1-iodobutane, performed by Steinmetz et al.in 1977) led to the determination of the B + C parameter for the anti-anti­and gauche-anti-conformers. Nearly 40 years later, this reinvestigation of 1- iodobutane, by high-resolution microwave spectroscopy, led to the determina­tion of rotational constants, centrifugal distortion constants, nuclear quadrupole coupling constants (NQCCs), and nuclear-sp rotation constants belonging to both of the two previously mentioned conformers, in addition to the gauche­ gauche-conformer, which was observed in this frequency regime for the first time. Comparisons between the three conformers of 1-iodobutanc and other iodo- and bromoalkanes are made, specifically throughmore » an analysis of the nuclear quadrupole coupling constants belonging to the iodine and bromine atoms in the respective chemical environments.« less

Electron-ion dissociative recombination rate constants relevant to the Titan atmosphere and the Interstellar Medium

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

Osborne, David; Lawson, Patrick; Adams, Nigel, E-mail: ngadams@uga.edu

Following the arrival of Cassini at Titan in 2004, the Titan atmosphere has been shown to contain large complex polycyclic-aromatic hydrocarbons. Since Cassini has provided a great deal of data, there exists a need for kinetic rate data to help with modeling this atmosphere. One type of kinetic data needed is electron-ion dissociative recombination (e-IDR) rate constants. These data are not readily available for larger compounds, such as naphthalene, or oxygen containing compounds, such as 1,4 dioxane or furan. Here, the rate constants for naphthalene, 1,4 dioxane, and furan have been measured and their temperature dependencies are determined when possible,more » using the University of Georgia's Variable Temperature Flowing Afterglow. The rate constants are compared with those previously published for other compounds; these show trends which illustrate the effects which multi-rings and oxygen heteroatoms substitutions have upon e-IDR rate constants.« less

Electron-ion dissociative recombination rate constants relevant to the Titan atmosphere and the Interstellar Medium

NASA Astrophysics Data System (ADS)

Osborne, David; Lawson, Patrick; Adams, Nigel

2014-01-01

Following the arrival of Cassini at Titan in 2004, the Titan atmosphere has been shown to contain large complex polycyclic-aromatic hydrocarbons. Since Cassini has provided a great deal of data, there exists a need for kinetic rate data to help with modeling this atmosphere. One type of kinetic data needed is electron-ion dissociative recombination (e-IDR) rate constants. These data are not readily available for larger compounds, such as naphthalene, or oxygen containing compounds, such as 1,4 dioxane or furan. Here, the rate constants for naphthalene, 1,4 dioxane, and furan have been measured and their temperature dependencies are determined when possible, using the University of Georgia's Variable Temperature Flowing Afterglow. The rate constants are compared with those previously published for other compounds; these show trends which illustrate the effects which multi-rings and oxygen heteroatoms substitutions have upon e-IDR rate constants.

A study of the conformational isomerism of 1-iodobutane by high resolution rotational spectroscopy

DOE PAGES

Arsenault, Eric A.; Obenchain, Daniel A.; Blake, Thomas A.; ...

2017-05-01

The first microwave study of 1-iodobutane, performed by Steinmetz et al. in 1977, led to the determination of the B+C parameter for the anti-anti- and gauche-anti-conformers. Nearly 40 years later, in this paper this reinvestigation of 1-iodobutane, by high-resolution microwave spectroscopy, led to the determination of rotational constants, centrifugal distortion constants, nuclear quadrupole coupling constants (NQCCs), and nuclear-spin rotation constants belonging to both of the two previously mentioned conformers, in addition to the gauche-gauche-conformer, which was observed in this frequency regime for the first time. Finally, comparisons between the three conformers of 1-iodobutane and other iodo- and bromoalkanes are made,more » specifically through an analysis of the nuclear quadrupole coupling constants belonging to the iodine and bromine atoms in the respective chemical environments.« less

Modeling and validation of autoinducer-mediated bacterial gene expression in microfluidic environments

PubMed Central

Austin, Caitlin M.; Stoy, William; Su, Peter; Harber, Marie C.; Bardill, J. Patrick; Hammer, Brian K.; Forest, Craig R.

2014-01-01

Biosensors exploiting communication within genetically engineered bacteria are becoming increasingly important for monitoring environmental changes. Currently, there are a variety of mathematical models for understanding and predicting how genetically engineered bacteria respond to molecular stimuli in these environments, but as sensors have miniaturized towards microfluidics and are subjected to complex time-varying inputs, the shortcomings of these models have become apparent. The effects of microfluidic environments such as low oxygen concentration, increased biofilm encapsulation, diffusion limited molecular distribution, and higher population densities strongly affect rate constants for gene expression not accounted for in previous models. We report a mathematical model that accurately predicts the biological response of the autoinducer N-acyl homoserine lactone-mediated green fluorescent protein expression in reporter bacteria in microfluidic environments by accommodating these rate constants. This generalized mass action model considers a chain of biomolecular events from input autoinducer chemical to fluorescent protein expression through a series of six chemical species. We have validated this model against experimental data from our own apparatus as well as prior published experimental results. Results indicate accurate prediction of dynamics (e.g., 14% peak time error from a pulse input) and with reduced mean-squared error with pulse or step inputs for a range of concentrations (10 μM–30 μM). This model can help advance the design of genetically engineered bacteria sensors and molecular communication devices. PMID:25379076

Reynolds stress scaling in pipe flow turbulence—first results from CICLoPE

PubMed Central

Fiorini, T.; Bellani, G.; Talamelli, A.

2017-01-01

This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×104 are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend–Perry constant of A2≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend–Perry constant, i.e. A2,w≈A2/2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities. This article is part of the themed issue ‘Toward the development of high-fidelity models of wall turbulence at large Reynolds number’. PMID:28167586

IMPROVED V II log(gf) VALUES, HYPERFINE STRUCTURE CONSTANTS, AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

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

Wood, M. P.; Lawler, J. E.; Den Hartog, E. A.

2014-10-01

New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Two spectrometers, independent radiometric calibration methods, and independent data analysis routines enable a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fittingmore » line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log ε(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = –2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.« less

Calculation of kinetic rate constants from thermodynamic data

NASA Technical Reports Server (NTRS)

Marek, C. John

1995-01-01

A new scheme for relating the absolute value for the kinetic rate constant k to the thermodynamic constant Kp is developed for gases. In this report the forward and reverse rate constants are individually related to the thermodynamic data. The kinetic rate constants computed from thermodynamics compare well with the current kinetic rate constants. This method is self consistent and does not have extensive rules. It is first demonstrated and calibrated by computing the HBr reaction from H2 and Br2. This method then is used on other reactions.

Constant-concentration boundary condition: Lessons from the HYDROCOIN variable-density groundwater benchmark problem

USGS Publications Warehouse

Konikow, Leonard F.; Sanford, W.E.; Campbell, P.J.

1997-01-01

In a solute-transport model, if a constant-concentration boundary condition is applied at a node in an active flow field, a solute flux can occur by both advective and dispersive processes. The potential for advective release is demonstrated by reexamining the Hydrologic Code Intercomparison (HYDROCOIN) project case 5 problem, which represents a salt dome overlain by a shallow groundwater system. The resulting flow field includes significant salinity and fluid density variations. Several independent teams simulated this problem using finite difference or finite element numerical models. We applied a method-of-characteristics model (MOCDENSE). The previous numerical implementations by HYDROCOIN teams of a constant-concentration boundary to represent salt release by lateral dispersion only (as stipulated in the original problem definition) was flawed because this boundary condition allows the release of salt into the flow field by both dispersion and advection. When the constant-concentration boundary is modified to allow salt release by dispersion only, significantly less salt is released into the flow field. The calculated brine distribution for case 5 depends very little on which numerical model is used, as long as the selected model is solving the proper equations. Instead, the accuracy of the solution depends strongly on the proper conceptualization of the problem, including the detailed design of the constant-concentration boundary condition. The importance and sensitivity to the manner of specification of this boundary does not appear to have been recognized previously in the analysis of this problem.

Aqueous infrared carboxylate absorbances: Aliphatic di-acids

USGS Publications Warehouse

Cabaniss, S.E.; Leenheer, J.A.; McVey, I.F.

1998-01-01

Aqueous attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra of 18 aliphatic di-carboxylic acids are reported as a function of pH. The spectra show isosbestic points and intensity changes which indicate that Beer's law is obeyed, and peak frequencies lie within previously reported ranges for aqueous carboxylates and pure carboxylic acids. Intensity sharing from the symmetric carboxylate stretch is evident in many cases, so that bands which are nominally due to alkyl groups show increased intensity at higher pH. The asymmetric stretch of the HA- species is linearly related to the microscopic acidity constant of the H2A species, with ??pK 2 intervening atoms). The results suggest that aqueous ATR-FTIR may be able to estimate 'intrinsic' pKa values of carboxylic acids, in addition to providing quantitative estimates of ionization. ?? 1998 Elsevier Science B.V. All rights reserved.

Linguistic analysis of IPCC summaries for policymakers and associated coverage

NASA Astrophysics Data System (ADS)

Barkemeyer, Ralf; Dessai, Suraje; Monge-Sanz, Beatriz; Renzi, Barbara Gabriella; Napolitano, Giulio

2016-03-01

The Intergovernmental Panel on Climate Change (IPCC) Summary for Policymakers (SPM) is the most widely read section of IPCC reports and the main springboard for the communication of its assessment reports. Previous studies have shown that communicating IPCC findings to a variety of scientific and non-scientific audiences presents significant challenges to both the IPCC and the mass media. Here, we employ widely established sentiment analysis tools and readability metrics to explore the extent to which information published by the IPCC differs from the presentation of respective findings in the popular and scientific media between 1990 and 2014. IPCC SPMs clearly stand out in terms of low readability, which has remained relatively constant despite the IPCC’s efforts to consolidate and readjust its communications policy. In contrast, scientific and quality newspaper coverage has become increasingly readable and emotive. Our findings reveal easy gains that could be achieved in making SPMs more accessible for non-scientific audiences.

Parvenus and conflict in elite cohorts.

PubMed

Michael Lindsay, D; Schachter, Ariela; Porter, Jeremy R; Sorge, David C

2014-09-01

Previous studies find that greater workplace diversity leads to higher degrees of conflict in low and medium-status workgroups. This paper examines whether similar dynamics operate in elite cohorts. We use data from a survey of White House Fellows (N=475) to look at how the presence of parvenus-individuals from underrepresented groups in elite environments-change the rate at which fellows reported conflict with each other and with the director of the program. We find that there is no unified "parvenu experience." Analysis of the interaction between race and cohort diversity reveals inflection points consistent with Kanter's (1977) theory of tokenism, but the effects of increasing diversity diverge: for Hispanics, conflict with the director increases with diversity, while for Asians, conflict falls with diversity. While other groups' level of conflict with their peers stays roughly constant, Asians' reported level of conflict with their peers increases with diversity. Copyright © 2014 Elsevier Inc. All rights reserved.

High-resolution two-photon spectroscopy of a 5 p56 p ←5 p6 transition of xenon

NASA Astrophysics Data System (ADS)

Altiere, Emily; Miller, Eric R.; Hayamizu, Tomohiro; Jones, David J.; Madison, Kirk W.; Momose, Takamasa

2018-01-01

We report high-resolution Doppler-free two-photon excitation spectroscopy of Xe from the ground state to the 5 p5(P 3 /2 2 ) 6 p [3 /2 ] 2 2 electronic excited state. This is a first step to developing a comagnetometer using polarized 129Xe atoms for planned neutron electric dipole moment measurements at TRIUMF. Narrow linewidth radiation at 252.5 nm produced by a continuous wave laser was built up in an optical cavity to excite the two-photon transition, and the near-infrared emission from the 5 p56 p excited state to the 5 p56 s intermediate electronic state was used to detect the two-photon transition. Hyperfine constants and isotope shift parameters were evaluated and compared with previously reported values. In addition, the detected photon count rate was estimated from the observed intensities.

A Web site-based reporting system for monitoring home treatment during oral immunotherapy for food allergy.

PubMed

Nachshon, Liat; Goldberg, Michael R; Elizur, Arnon; Levy, Michael B; Schwartz, Naama; Katz, Yitzhak

2015-06-01

Reactions during the home treatment phase of oral immunotherapy (OIT) are not uncommon. An ongoing accurate reporting of home treatment outcomes is crucial for the safety and success of OIT. Previous reports have shown that as few as 20% of patients are truly compliant with paper-based diaries. To develop a Web site-based electronic reporting system (web-RS) for monitoring home treatment during OIT for food allergy. A web-RS was developed and incorporated a thorough questionnaire querying for pertinent data including the dose(s) consumed, occurrence and details of adverse reactions, treatment(s), and relevant potential exacerbating factors. All patients enrolled in milk, peanut, or egg OIT programs for at least 4 weeks from November 2012 through January 2014 were introduced to web-RS (n = 157). Successful reporting through web-RS was defined by consecutive reporting during the first home treatment phase (24 days) after its introduction. Comparisons were made with a previous group of OIT-treated patients (n = 100) who reported by E-mail. Successful reporting was achieved by 142 of 157 patients (90.44%) in contrast to a 75% success rate with E-mail (P = .0009). The odds for successful reporting using web-RS were 3.1 (95% confidence interval 1.6-6.3) times higher compared with using E-mail. Mild reactions were reported more frequently with web-RS (P = .0032). Patient reports were constantly available in real time for medical staff review. No complaints regarding web-RS feasibility were reported. One risk factor for failure to use web-RS was a patient's prior successful OIT experience without using web-RS (P = .012). A web-RS can be a powerful tool for improving OIT safety by achieving a high level of patient cooperation in reporting home treatment results. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

A gravitational-wave standard siren measurement of the Hubble constant

DOE PAGES

Abbott, B. P.; Abbott, R.; Abbott, T. D.; ...

2017-10-16

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO–Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identificationof an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observationsmore » enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. Furthermore, this value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.« less

A gravitational-wave standard siren measurement of the Hubble constant

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

Abbott, B. P.; Abbott, R.; Abbott, T. D.

On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817—a strong signal from the merger of a binary neutron-star system. Less than two seconds after the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO–Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identificationof an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first ‘multi-messenger’ astronomical observation. Such observationsmore » enable GW170817 to be used as a ‘standard siren’ (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic ‘distance ladder’: the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. Furthermore, this value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.« less

Quantitative production of compound I from a cytochrome P450 enzyme at low temperatures. Kinetics, activation parameters, and kinetic isotope effects for oxidation of benzyl alcohol.

PubMed

Wang, Qin; Sheng, Xin; Horner, John H; Newcomb, Martin

2009-08-05

Cytochrome P450 enzymes are commonly thought to oxidize substrates via an iron(IV)-oxo porphyrin radical cation transient termed Compound I, but kinetic studies of P450 Compounds I are essentially nonexistent. We report production of Compound I from cytochrome P450 119 (CYP119) in high conversion from the corresponding Compound II species at low temperatures in buffer mixtures containing 50% glycerol by photolysis with 365 nm light from a pulsed lamp. Compound I was studied as a reagent in oxidations of benzyl alcohol and its benzylic mono- and dideuterio isotopomers. Pseudo-first-order rate constants obtained at -50 degrees C with concentrations of substrates between 1.0 and 6.0 mM displayed saturation kinetics that gave binding constants for the substrate in the Compound I species (K(bind)) and first-order rate constants for the oxidation reactions (k(ox)). Representative results are K(bind) = 214 M(-1) and k(ox) = 0.48 s(-1) for oxidation of benzyl alcohol. For the dideuterated substrate C(6)H(5)CD(2)OH, kinetics were studied between -50 and -25 degrees C, and a van't Hoff plot for complexation and an Arrhenius plot for the oxidation reaction were constructed. The H/D kinetic isotope effects (KIEs) at -50 degrees C were resolved into a large primary KIE (P = 11.9) and a small, inverse secondary KIE (S = 0.96). Comparison of values extrapolated to 22 degrees C of both the rate constant for oxidation of C(6)H(5)CD(2)OH and the KIE for the nondeuterated and dideuterated substrates to values obtained previously in laser flash photolysis experiments suggested that tunneling could be a significant component of the total rate constant at -50 degrees C.

Immunoglobulin domain interface exchange as a platform technology for the generation of Fc heterodimers and bispecific antibodies.

PubMed

Skegro, Darko; Stutz, Cian; Ollier, Romain; Svensson, Emelie; Wassmann, Paul; Bourquin, Florence; Monney, Thierry; Gn, Sunitha; Blein, Stanislas

2017-06-09

Bispecific antibodies (bsAbs) are of significant importance to the development of novel antibody-based therapies, and heavy chain (Hc) heterodimers represent a major class of bispecific drug candidates. Current technologies for the generation of Hc heterodimers are suboptimal and often suffer from contamination by homodimers posing purification challenges. Here, we introduce a new technology based on biomimicry wherein the protein-protein interfaces of two different immunoglobulin (Ig) constant domain pairs are exchanged in part or fully to design new heterodimeric domains. The method can be applied across Igs to design Fc heterodimers and bsAbs. We investigated interfaces from human IgA CH3, IgD CH3, IgG1 CH3, IgM CH4, T-cell receptor (TCR) α/β, and TCR γ/δ constant domain pairs, and we found that they successfully drive human IgG1 CH3 or IgM CH4 heterodimerization to levels similar to or above those of reference methods. A comprehensive interface exchange between the TCR α/β constant domain pair and the IgG1 CH3 homodimer was evidenced by X-ray crystallography and used to engineer examples of bsAbs for cancer therapy. Parental antibody pairs were rapidly reformatted into scalable bsAbs that were free of homodimer traces by combining interface exchange, asymmetric Protein A binding, and the scFv × Fab format. In summary, we successfully built several new CH3- or CH4-based heterodimers that may prove useful for designing new bsAb-based therapeutics, and we anticipate that our approach could be broadly implemented across the Ig constant domain family. To our knowledge, CH4-based heterodimers have not been previously reported. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Factors affecting the process performance of biofiltration

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

Kopchynski, D.M.; Farmer, R.W.; Maier, W.J.

1996-11-01

Biofiltration is an emerging biological treatment technology for the removal of airborne VOCs from industrial process waste streams. Removal of air-phase VOCs by biofiltration is accomplished by contacting a process airstream with an active microbial biofilm attached to a solid phase packing. VOCs that partition into the biofilm are aerobically oxidized to the endproducts of water, carbon dioxide and salts. A multiple reactor biofiltration pilot plant test program has been in progress at the University of Minnesota Environmental Engineering Laboratories since 1992. The primary goal of the program is to study factors that affect biofiltration process performance. Initial results ofmore » this test program were reported in a previous conference paper and master`s thesis. This paper presents the results of more recent studies that focus on the effects of: (1) biofilm accumulation (which in turn causes a decrease in biofilter bed porosity and packing bed surface area), (2) rates of nutrient addition, and (3) chemical properties of the target contaminant, on biofiltration removal performance. Removal performance was evaluated by determining biofilter removal capacities and efficiencies for various substrate feeds. The performance parameters were measured under constant contaminant inlet concentrations and under constant temperature. Three VOCs were selected for study and they are: MEK, (methyl ethyl ketone), xylene, and hexane. MEK, xylene, and hexane were chosen because they are representative of widely used industrial solvents and they have significantly different Henry`s law constants relative to each other (the MEK value < Xylene value < Hexane value). Henry`s law constants quantify the partitioning of a chemical between the air and water-biofilm phase and therefore can be used to correlate the effect of chemical properties on biofilter removal capacities. This paper also introduces a new model for the biofiltration process.« less

Stability of bound species during alkene reactions on solid acids

NASA Astrophysics Data System (ADS)

Sarazen, Michele L.; Iglesia, Enrique

2017-05-01

This study reports the thermodynamics of bound species derived from ethene, propene, n-butene, and isobutene on solid acids with diverse strength and confining voids. Density functional theory (DFT) and kinetic data indicate that covalently bound alkoxides form C-C bonds in the kinetically relevant step for dimerization turnovers on protons within TON (0.57 nm) and MOR (0.67 nm) zeolitic channels and on stronger acids HPW (polyoxometalate clusters on silica). Turnover rates for mixed alkenes give relative alkoxide stabilities; the respective adsorption constants are obtained from in situ infrared spectra. Tertiary alkoxides (from isobutene) within larger voids (MOR, HPW) are more stable than less substituted isomers but are destabilized within smaller concave environments (TON) because framework distortions are required to avoid steric repulsion. Adsorption constants are similar on MOR and HPW for each alkoxide, indicating that binding is insensitive to acid strength for covalently bound species. DFT-derived formation free energies for alkoxides with different framework attachments and backbone length/structure agree with measurements when dispersion forces, which mediate stabilization by confinement in host-guest systems, are considered. Theory reveals previously unrecognized framework distortions that balance the C-O bond lengths required for covalency with host-guest distances that maximize van der Waals contacts. These distortions, reported here as changes in O-atom locations and dihedral angles, become stronger for larger, more substituted alkoxides. The thermodynamic properties reported here for alkoxides and acid hosts differing in size and conjugate-anion stability are benchmarked against DFT-derived free energies; their details are essential to design host-guest pairs that direct alkoxide species toward specific products.

Control of the Protein Turnover Rates in Lemna minor

PubMed Central

Trewavas, A.

1972-01-01

The control of protein turnover in Lemna minor has been examined using a method described in the previous paper for determining the rate constants of synthesis and degradation of protein. If Lemna is placed on water, there is a reduction in the rate constants of synthesis of protein and an increase (3- to 6-fold) in the rate constant of degradation. The net effect is a loss of protein from the tissue. Omission of nitrate, phosphate, sulfate, magnesium, or calcium results in increases in the rate constant of degradation of protein. An unusual dual effect of benzyladenine on the turnover constants has been observed. Treatment of Lemna grown on sucrose-mineral salts with benzyladenine results in alterations only in the rate constant of synthesis. Treatment of Lemna grown on water with benzyladenine alters only the rate constant of degradation. Abscisic acid on the other hand alters both rate constants of synthesis and degradation of protein together. Inclusion of growth-inhibiting amino acids in the medium results in a reduction in the rate constants of synthesis and increases in the rate constant of degradation of protein. It is concluded that the rate of turnover of protein in Lemna is very dependent on the composition of the growth medium. Conditions which reduce growth rates also reduce the rates of synthesis of protein and increase those of degradation. PMID:16657895

Grunwald-Winstein Analysis - Isopropyl Chloroformate Solvolysis Revisited

PubMed Central

D’Souza, Malcolm J.; Reed, Darneisha N.; Erdman, Kevin J.; Kyong, Jin Burm; Kevill, Dennis N.

2009-01-01

Specific rates of solvolysis at 25 °C for isopropyl chloroformate (1) in 24 solvents of widely varying nucleophilicity and ionizing power, plus literature values for studies in water and formic acid, are reported. Previously published solvolytic rate constants at 40.0 °C are supplemented with two additional values in the highly ionizing fluoroalcohols. These rates are now are analyzed using the one and two-term Grunwald-Winstein Equations. In the more ionizing solvents including ten fluoroalcohols negligible sensitivities towards changes in solvent nucleophilicity (l) and very low sensitivities towards changes in solvent ionizing power (m) values are obtained, evocative to those previously observed for 1-adamantyl and 2-adamantyl chloroformates 2 and 3. These observations are rationalized in terms of a dominant solvolysis-decomposition with loss of the CO2 molecule. In nine of the more nucleophilic pure alchohols and aqueous solutions an association-dissociation mechanism is believed to be operative. Deficiencies in the acid production indicate 2-33% isopropyl chloride formation, with the higher values in less nucleophilic solvents. PMID:19399225

The distribution of carbon monoxide and ozone in the free troposphere

NASA Technical Reports Server (NTRS)

Seiler, G.; Fishman, J.

1981-01-01

The two-dimensional distributions of CO and O3 in the free troposphere during July and August, 1974, are discussed. The data confirm the previous findings that both of these gases are considerably more abundant in the northern hemisphere, but the degree of the asymmetry is somewhat different from what had been reported previously, especially for CO. When examined with respect to other available data sets, the conclusion is drawn that a pronounced seasonal cycle exists for CO in both hemispheres which may be driven by the likely seasonal cycle of the OH radical. The data also indicate that CO concentrations exhibit significant variability with height in the northern hemisphere, whereas southern hemispheric concentrations are quite constant with altitude except in cases where interhemispheric exchange of air may be occurring. A discussion on the vertical and horizontal transport processes inferred from the CO and O3 measurements is presented. The possible interdependence of the photochemical cycles of these two trace gases is also discussed.

Preparation of fine single crystals of magnetic superconductor RuSr2GdCu2O8-δ by partial melting

NASA Astrophysics Data System (ADS)

Yamaki, Kazuhiro; Bamba, Yoshihiro; Irie, Akinobu

2018-03-01

In this study, fine uniform RuSr2GdCu2O8-δ (RuGd-1212) single crystals have been successfully prepared by partial melting. Synthesis temperature could be lowered to a value not exceeding the decomposition temperature of RuGd-1212 using the Sr-Gd-Cu-O flux. The crystals grown by alumina boats are cubic, which coincides with the result of a previous study of RuGd-1212 single crystals using platinum crucibles. The single crystals were up to 15 × 15 × 15 µm3 in size and their lattice constants were consistent with those of polycrystalline samples reported previously. Although the present size of single crystals is not sufficient for measurements, the partial melting technique will be beneficial for future progress of research using RuGd-1212 single crystals. Appropriate nominal composition, sintering atmosphere, and temperature are essential factors for growing RuGd-1212 single crystals.

Flame Chemiluminescence Rate Constants for Quantitative Microgravity Combustion Diagnostics

NASA Technical Reports Server (NTRS)

Luque, Jorge; Smith, Gregory P.; Jeffries, Jay B.; Crosley, David R.; Weiland, Karen (Technical Monitor)

2001-01-01

Absolute excited state concentrations of OH(A), CH(A), and C2(d) were determined in three low pressure premixed methane-air flames. Two dimensional images of chemiluminescence from these states were recorded by a filtered CCD camera, processed by Abel inversion, and calibrated against Rayleigh scattering, Using a previously validated 1-D flame model with known chemistry and excited state quenching rate constants, rate constants are extracted for the reactions CH + O2 (goes to) OH(A) + CO and C2H + O (goes to) CH(A) + CO at flame temperatures. Variations of flame emission intensities with stoichiometry agree well with model predictions.

Spring Constants for Stacks of Curved Leaves of Pyrolytic Boron Nitride

NASA Technical Reports Server (NTRS)

Kaforey, M. L.; Deeb, C. W.; Matthiesen, D. H.

1999-01-01

Stacks of curved leaves of pyrolytic boron nitride (PBN) were deflected and the force versus deflection data was recorded. From this data, the spring constant for a given spring geometry (radius of curvature of a leaf, width of a leaf, thickness of a leaf, and number of leaves in the stack) was determined. These experiments were performed at room temperature, 500 C and 1000 C. However, temperature was not found to affect the spring constant. The measured values were generally within one order of magnitude of predictions made using a previously derived equation for a simply supported cylindrical section with a line force at the center.

A novel technique for measurement of thermal rate constants and temperature dependences of dissociative recombination: CO{sub 2}{sup +}, CF{sub 3}{sup +}, N{sub 2}O{sup +}, C{sub 7}H{sub 8}{sup +}, C{sub 7}H{sub 7}{sup +}, C{sub 6}H{sub 6}{sup +}, C{sub 6}H{sub 5}{sup +}, C{sub 5}H{sub 6}{sup +}, C{sub 4}H{sub 4}{sup +}, and C{sub 3}H{sub 3}{sup +}

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

Fournier, Joseph A.; Shuman, Nicholas S.; Melko, Joshua J.

A novel technique using a flowing afterglow-Langmuir probe apparatus for measurement of temperature dependences of rate constants for dissociative recombination (DR) is presented. Low ({approx}10{sup 11} cm{sup -3}) concentrations of a neutral precursor are added to a noble gas/electron afterglow plasma thermalized at 300-500 K. Charge exchange yields one or many cation species, each of which may undergo DR. Relative ion concentrations are monitored at a fixed reaction time while the initial plasma density is varied between 10{sup 9} and 10{sup 10} cm{sup -3}. Modeling of the decrease in concentration of each cation relative to the non-recombining noble gas cationmore » yields the rate constant for DR. The technique is applied to several species (O{sub 2}{sup +}, CO{sub 2}{sup +}, CF{sub 3}{sup +}, N{sub 2}O{sup +}) with previously determined 300 K values, showing excellent agreement. The measurements of those species are extended to 500 K, with good agreement to literature values where they exist. Measurements are also made for a range of C{sub n}H{sub m}{sup +} (C{sub 7}H{sub 7}{sup +}, C{sub 7}H{sub 8}{sup +}, C{sub 5}H{sub 6}{sup +}, C{sub 4}H{sub 4}{sup +}, C{sub 6}H{sub 5}{sup +}, C{sub 3}H{sub 3}{sup +}, and C{sub 6}H{sub 6}{sup +}) derived from benzene and toluene neutral precursors. C{sub n}H{sub m}{sup +} DR rate constants vary from 8-12 Multiplication-Sign 10{sup -7} cm{sup 3} s{sup -1} at 300 K with temperature dependences of approximately T{sup -0.7}. Where prior measurements exist these results are in agreement, with the exception of C{sub 3}H{sub 3}{sup +} where the present results disagree with a previously reported flat temperature dependence.« less

The gaseous explosive reaction at constant pressure : the reaction order and reaction rate

NASA Technical Reports Server (NTRS)

Stevens, F W

1931-01-01

The data given in this report covers the explosive limits of hydrocarbon fuels. Incidental to the purpose of the investigation here reported, the explosive limits will be found to be expressed for the condition of constant pressure, in the fundamental terms of concentrations (partial pressures) of fuel and oxygen.

A Chemical Activation Study of the Unimolecular Reactions of CD3CD2CHCl2 and CHCl2CHCl2 with Analysis of the 1,1-HCl Elimination Pathway.

PubMed

Larkin, Allie C; Nestler, Matthew J; Smith, Caleb A; Heard, George L; Setser, Donald W; Holmes, Bert E

2016-10-03

Chemically activated C2D5CHCl2 molecules were generated with 88 kcal mol-1 of vibrational energy by the recombination of C2D5 and CHCl2 radicals in a room temperature bath gas. The competing 2,1-DCl and 1,1-HCl unimolecular reactions were identified by the observation of the CD3CD=CHCl and CD3CD=CDCl products. The initial CD3CD2C-Cl carbene product from 1,1-HCl elimination rearranges to CD3CD=CDCl under the conditions of the experiments. The experimental rate constants were 2.7 x107 and 0.47 x107 s-1 for 2,1-DCl and 1,1-HCl elimination reactions, respectively, which corresponds to branching fractions of 0.84 and 0.16. The experimental rate constants were compared to calculated statistical rate constants to assign threshold energies of 54 and ≈ 66 kcal mol-1 for the 1,2-DCl and 1,1-HCl reactions, respectively. The statistical rate constants were obtained from models developed from electronic-structure calculations for the molecule and its transition states. The rate constant (5.3 x 107 s-1) for the unimolecular decomposition of CHCl2CHCl2 molecules formed with 82 kcal mol-1 of vibrational energy by the recombination of CHCl2 radicals also is reported. Based upon the magnitude of the calculated rate constant, 1,1-HCl elimination must contribute less than 15% to the reaction; 1,2-HCl elimination is the major reaction and the threshold energy is 59 kcal mol-1. Calculations also were done to analyze previously published rate constants for chemically activated CD2Cl-CHCl2 molecules with 86 kcal mol-1 of energy in order to obtain a better overall description of the nature of the 1,1-HCl pathway for 1,1-dichloroalkanes. The interplay of the threshold energies for the 2,1-HCl and 1,1-HCl reactions and the available energy determines the product branching fractions for individual molecules. The unusual nature of the transition state for 1,1-HCl elimination is discussed.

Absolute rate of the reaction of Cl(p-2) with molecular hydrogen from 200 - 500 K

NASA Technical Reports Server (NTRS)

Whytock, D. A.; Lee, J. H.; Michael, J. V.; Payne, W. A.; Stief, L. J.

1976-01-01

Rate constants for the reaction of atomic chlorine with hydrogen are measured from 200 - 500 K using the flash photolysis-resonance fluorescence technique. The results are compared with previous work and are discussed with particular reference to the equilibrium constant for the reaction and to relative rate data for chlorine atom reactions. Theoretical calculations, using the BEBO method with tunneling, give excellent agreement with experiment.

Measurement of the decay constant f(Ds+) using D(s+)-->l+ nu.

PubMed

Artuso, M; Blusk, S; Butt, J; Khalil, S; Li, J; Menaa, N; Mountain, R; Nisar, S; Randrianarivony, K; Sia, R; Skwarnicki, T; Stone, S; Wang, J C; Bonvicini, G; Cinabro, D; Dubrovin, M; Lincoln, A; Asner, D M; Edwards, K W; Naik, P; Briere, R A; Ferguson, T; Tatishvili, G; Vogel, H; Watkins, M E; Rosner, J L; Adam, N E; Alexander, J P; Cassel, D G; Duboscq, J E; Ehrlich, R; Fields, L; Gibbons, L; Gray, R; Gray, S W; Hartill, D L; Heltsley, B K; Hertz, D; Jones, C D; Kandaswamy, J; Kreinick, D L; Kuznetsov, V E; Mahlke-Krüger, H; Mohapatra, D; Onyisi, P U E; Patterson, J R; Peterson, D; Pivarski, J; Riley, D; Ryd, A; Sadoff, A J; Schwarthoff, H; Shi, X; Stroiney, S; Sun, W M; Wilksen, T; Athar, S B; Patel, R; Yelton, J; Rubin, P; Cawlfield, C; Eisenstein, B I; Karliner, I; Kim, D; Lowrey, N; Selen, M; White, E J; Wiss, J; Mitchell, R E; Shepherd, M R; Besson, D; Pedlar, T K; Cronin-Hennessy, D; Gao, K Y; Hietala, J; Kubota, Y; Klein, T; Lang, B W; Poling, R; Scott, A W; Smith, A; Zweber, P; Dobbs, S; Metreveli, Z; Seth, K K; Tomaradze, A; Ernst, J; Ecklund, K M; Severini, H; Love, W; Savinov, V; Aquines, O; Lopez, A; Mehrabyan, S; Mendez, H; Ramirez, J; Huang, G S; Miller, D H; Pavlunin, V; Sanghi, B; Shipsey, I P J; Xin, B; Adams, G S; Anderson, M; Cummings, J P; Danko, I; Hu, D; Moziak, B; Napolitano, J; He, Q; Insler, J; Muramatsu, H; Park, C S; Thorndike, E H; Yang, F

2007-08-17

We measure the decay constant f(Ds+) using the D(s+)-->l+ nu channel, where the l+ designates either a mu+ or a tau+, when the tau+ -->pi+ nu. Using both measurements we find f(Ds+)=274+/-13+/-7 MeV. Combining with our previous determination of f(D+), we compute the ratio f(Ds+)/f(D+)=1.23+/-0.11+/-0.04. We compare with theoretical estimates.

The right whale mandatory ship reporting system: a retrospective

PubMed Central

Adams, Jeffrey D.; Asaro, Michael J.; Cole, Timothy V.N.; Moore, Katie S.; Ward-Geiger, Leslie I.; Zoodsma, Barbara J.

2015-01-01

In 1998, the United States sought and received International Maritime Organization-endorsement of two Mandatory Ship Reporting (MSR) systems designed to improve mariner awareness about averting ship collisions with the endangered North Atlantic right whale (Eubalaena glacialis). Vessel collisions are a serious threat to the right whale and the program was among the first formal attempts to reduce this threat. Under the provisions of the MSR, all ships >300 gross tons are required to report their location, speed, and destination to a shore-based station when entering two key right whale habitats: one in waters off New England and one off coastal Georgia and Florida. In return, reporting ships receive an automatically-generated message, delivered directly to the ship’s bridge, that provides information about right whale vulnerability to vessel collisions and actions mariners can take to avoid collisions. The MSR has been in operation continuously from July 1999 to the present. Archived incoming reports provided a 15-plus year history of ship operations in these two locations. We analyzed a total of 26,772 incoming MSR messages logged between July 1999 and December 2013. Most ships that were required to report did so, and compliance rates were generally constant throughout the study period. Self-reported vessel speeds when entering the systems indicated that most ships travelled between 10 and 16 (range = 5–20 +) knots. Ship speeds generally decreased in 2009 to 2013 following implementation of vessel speed restrictions. The number of reports into the southern system remained relatively constant following a steady increase through 2007, but numbers in the northern system decreased annually beginning in 2008. If reporting is indicative of long-term patterns in shipping operations, it reflects noteworthy changes in marine transportation. Observed declines in ship traffic are likely attributable to the 2008–2009 economic recession, the containerized shipping industry making increased use of larger ships that made fewer trips, and diminished oil/gas US imports as previously inaccessible domestic deposits were exploited. Recent declines in shipping activity likely resulted in lowered collision risks for right whales and reduced their exposure to underwater noise from ships. PMID:25861555

The right whale mandatory ship reporting system: a retrospective.

PubMed

Silber, Gregory K; Adams, Jeffrey D; Asaro, Michael J; Cole, Timothy V N; Moore, Katie S; Ward-Geiger, Leslie I; Zoodsma, Barbara J

2015-01-01

In 1998, the United States sought and received International Maritime Organization-endorsement of two Mandatory Ship Reporting (MSR) systems designed to improve mariner awareness about averting ship collisions with the endangered North Atlantic right whale (Eubalaena glacialis). Vessel collisions are a serious threat to the right whale and the program was among the first formal attempts to reduce this threat. Under the provisions of the MSR, all ships >300 gross tons are required to report their location, speed, and destination to a shore-based station when entering two key right whale habitats: one in waters off New England and one off coastal Georgia and Florida. In return, reporting ships receive an automatically-generated message, delivered directly to the ship's bridge, that provides information about right whale vulnerability to vessel collisions and actions mariners can take to avoid collisions. The MSR has been in operation continuously from July 1999 to the present. Archived incoming reports provided a 15-plus year history of ship operations in these two locations. We analyzed a total of 26,772 incoming MSR messages logged between July 1999 and December 2013. Most ships that were required to report did so, and compliance rates were generally constant throughout the study period. Self-reported vessel speeds when entering the systems indicated that most ships travelled between 10 and 16 (range = 5-20 +) knots. Ship speeds generally decreased in 2009 to 2013 following implementation of vessel speed restrictions. The number of reports into the southern system remained relatively constant following a steady increase through 2007, but numbers in the northern system decreased annually beginning in 2008. If reporting is indicative of long-term patterns in shipping operations, it reflects noteworthy changes in marine transportation. Observed declines in ship traffic are likely attributable to the 2008-2009 economic recession, the containerized shipping industry making increased use of larger ships that made fewer trips, and diminished oil/gas US imports as previously inaccessible domestic deposits were exploited. Recent declines in shipping activity likely resulted in lowered collision risks for right whales and reduced their exposure to underwater noise from ships.

Jet-cooled laser-induced fluorescence spectroscopy of cyclohexoxy: rotational and fine structure of molecules in nearly degenerate electronic States.

PubMed

Liu, Jinjun; Miller, Terry A

2014-12-26

The rotational structure of the previously observed B̃(2)A' ← X̃(2)A″ and B̃(2)A' ← Ã(2)A' laser-induced fluorescence spectra of jet-cooled cyclohexoxy radical (c-C6H11O) [ Zu, L.; Liu, J.; Tarczay, G.; Dupré, P; Miller, T. A. Jet-cooled laser spectroscopy of the cyclohexoxy radical. J. Chem. Phys. 2004 , 120 , 10579 ] has been analyzed and simulated using a spectroscopic model that includes the coupling between the nearly degenerate X̃ and à states separated by ΔE. The rotational and fine structure of these two states is reproduced by a 2-fold model using one set of molecular constants including rotational constants, spin-rotation constants (ε's), the Coriolis constant (Aζt), the quenched spin-orbit constant (aζed), and the vibronic energy separation between the two states (ΔE0). The energy level structure of both states can also be reproduced using an isolated-state asymmetric top model with rotational constants and effective spin-rotation constants (ε's) and without involving Coriolis and spin-orbit constants. However, the spin-orbit interaction introduces transitions that have no intensity using the isolated-state model but appear in the observed spectra. The line intensities are well simulated using the 2-fold model with an out-of-plane (b-) transition dipole moment for the B̃ ← X̃ transitions and in-plane (a and c) transition dipole moment for the B̃ ← à transitions, requiring the symmetry for the X̃ (Ã) state to be A″ (A'), which is consistent with a previous determination and opposite to that of isopropoxy, the smallest secondary alkoxy radical. The experimentally determined Ã-X̃ separation and the energy level ordering of these two states with different (A' and A″) symmetries are consistent with quantum chemical calculations. The 2-fold model also enables the independent determination of the two contributions to the Ã-X̃ separation: the relativistic spin-orbit interaction (magnetic effect) and the nonrelativistic vibronic separation between the lowest vibrational energy levels of these two states due to both electrostatic interaction (Coulombic effect) and difference in zero-point energies (kinetic effect).

Coefficient of performance for a low-dissipation Carnot-like refrigerator with nonadiabatic dissipation

NASA Astrophysics Data System (ADS)

Hu, Yong; Wu, Feifei; Ma, Yongli; He, Jizhou; Wang, Jianhui; Hernández, A. Calvo; Roco, J. M. M.

2013-12-01

We study the coefficient of performance (COP) and its bounds for a Carnot-like refrigerator working between two heat reservoirs at constant temperatures Th and Tc, under two optimization criteria χ and Ω. In view of the fact that an “adiabatic” process usually takes finite time and is nonisentropic, the nonadiabatic dissipation and the finite time required for the adiabatic processes are taken into account by assuming low dissipation. For given optimization criteria, we find that the lower and upper bounds of the COP are the same as the corresponding ones obtained from the previous idealized models where any adiabatic process is undergone instantaneously with constant entropy. To describe some particular models with very fast adiabatic transitions, we also consider the influence of the nonadiabatic dissipation on the bounds of the COP, under the assumption that the irreversible entropy production in the adiabatic process is constant and independent of time. Our theoretical predictions match the observed COPs of real refrigerators more closely than the ones derived in the previous models, providing a strong argument in favor of our approach.

Electron attachment to CF{sub 3} and CF{sub 3}Br at temperatures up to 890 K: Experimental test of the kinetic modeling approach

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

Shuman, Nicholas S.; Miller, Thomas M.; Viggiano, Albert A.

Thermal rate constants and product branching fractions for electron attachment to CF{sub 3}Br and the CF{sub 3} radical have been measured over the temperature range 300-890 K, the upper limit being restricted by thermal decomposition of CF{sub 3}Br. Both measurements were made in Flowing Afterglow Langmuir Probe apparatuses; the CF{sub 3}Br measurement was made using standard techniques, and the CF{sub 3} measurement using the Variable Electron and Neutral Density Attachment Mass Spectrometry technique. Attachment to CF{sub 3}Br proceeds exclusively by the dissociative channel yielding Br{sup -}, with a rate constant increasing from 1.1 Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1}more » at 300 K to 5.3 Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1} at 890 K, somewhat lower than previous data at temperatures up to 777 K. CF{sub 3} attachment proceeds through competition between associative attachment yielding CF{sub 3}{sup -} and dissociative attachment yielding F{sup -}. Prior data up to 600 K showed the rate constant monotonically increasing, with the partial rate constant of the dissociative channel following Arrhenius behavior; however, extrapolation of the data using a recently proposed kinetic modeling approach predicted the rate constant to turn over at higher temperatures, despite being only {approx}5% of the collision rate. The current data agree well with the previous kinetic modeling extrapolation, providing a demonstration of the predictive capabilities of the approach.« less

Recovering a full dimensional quantum rate constant from a reduced dimensionality calculation: Application to the OH+CO{r_arrow}H+CO{sub 2} reaction

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

Dzegilenko, F.N.; Bowman, J.M.

1996-08-01

Two reduced dimensionality theories are used to calculate the thermal rate constant for the OH+CO{r_arrow}H+CO{sub 2} reaction. The standard theory employs energy-shift approximations to extract the full six degree-of-freedom quantum rate constant for this reaction from the previous two degree-of-freedom (2-DOF) quantum calculations of Hernandez and Clary [M.I. Hernandez and D.C. Clary, J. Chem. Phys. {bold 101}, 2779 (1994)]. Three extra bending modes and one extra {open_quote}{open_quote}spectator{close_quote}{close_quote} CO stretch mode are treated adiabatically in the harmonic fashion. The parameters of the exit channel transition state are used to evaluate the frequencies of those additional modes. A new reduced dimensionality theorymore » is also applied to this reaction. This theory explicitly addresses the finding from the 2-DOF calculations that the reaction proceeds mainly via complex formation. A J-shifting approximation has been used to take into account the initial states with non-zero values of total angular momentum in both reduced dimensionality theories. Cumulative reaction probabilities and thermal rate constants are calculated and compared with the previous quasiclassical and reduced dimensionality quantum calculations and with experiment. The rate constant from the new reduced dimensionality theory is between a factor of 5 and 100 times smaller than the statistical transition state theory result, and is in much better agreement with experiment. {copyright} {ital 1996 American Institute of Physics.}« less

The kinetics of the oxidation of ferrous iron in synthetic and natural waters

NASA Astrophysics Data System (ADS)

Davison, W.; Seed, G.

1983-01-01

The rate of oxidation of ferrous iron in a seasonally anoxic lake was measured on 39 occasions with respect to both depth and time. Sample disturbance was minimal as only oxygen had to be introduced to initiate the reaction. The data were consistent with the simple rate law for homogeneous chemical kinetics previously established for synthetic solutions. The rate constant for the oxidation reaction in lake water was indistinguishable from that measured in synthetic samples. It did not appear to be influenced by changes in the microbial populations or by changes in any particulate or soluble components in the water, including iron and manganese. Analysis of the errors inherent in the kinetic measurements showed that the estimation of pH was the major source of inaccuracy and that values of the rate constant determined by different workers could easily differ by a factor of six. The present data, together with a comprehensive survey of the literature, are used to suggest a 'universal' rate constant of ca. 2 × 10 13 M -2 atm -1 min -1 (range 1.5-3 × 10 13) in the rate law -d[Fe II]/dt = k[Fe II]pO 2 (OH-) 2 for natural freshwaters in the pH range 6.5-7.4. Discrepancies in the effects of ionic strength and interfering substances reported in the literature are highlighted. Generally substances have only been found to interfere at concentrations which far exceed those in most natural waters.

Audiovisual Temporal Recalibration for Speech in Synchrony Perception and Speech Identification

NASA Astrophysics Data System (ADS)

Asakawa, Kaori; Tanaka, Akihiro; Imai, Hisato

We investigated whether audiovisual synchrony perception for speech could change after observation of the audiovisual temporal mismatch. Previous studies have revealed that audiovisual synchrony perception is re-calibrated after exposure to a constant timing difference between auditory and visual signals in non-speech. In the present study, we examined whether this audiovisual temporal recalibration occurs at the perceptual level even for speech (monosyllables). In Experiment 1, participants performed an audiovisual simultaneity judgment task (i.e., a direct measurement of the audiovisual synchrony perception) in terms of the speech signal after observation of the speech stimuli which had a constant audiovisual lag. The results showed that the “simultaneous” responses (i.e., proportion of responses for which participants judged the auditory and visual stimuli to be synchronous) at least partly depended on exposure lag. In Experiment 2, we adopted the McGurk identification task (i.e., an indirect measurement of the audiovisual synchrony perception) to exclude the possibility that this modulation of synchrony perception was solely attributable to the response strategy using stimuli identical to those of Experiment 1. The characteristics of the McGurk effect reported by participants depended on exposure lag. Thus, it was shown that audiovisual synchrony perception for speech could be modulated following exposure to constant lag both in direct and indirect measurement. Our results suggest that temporal recalibration occurs not only in non-speech signals but also in monosyllabic speech at the perceptual level.

Electric Double-Layer Interaction between Dissimilar Charge-Conserved Conducting Plates.

PubMed

Chan, Derek Y C

2015-09-15

Small metallic particles used in forming nanostructured to impart novel optical, catalytic, or tribo-rheological can be modeled as conducting particles with equipotential surfaces that carry a net surface charge. The value of the surface potential will vary with the separation between interacting particles, and in the absence of charge-transfer or electrochemical reactions across the particle surface, the total charge of each particle must also remain constant. These two physical conditions require the electrostatic boundary condition for metallic nanoparticles to satisfy an equipotential whole-of-particle charge conservation constraint that has not been studied previously. This constraint gives rise to a global charge conserved constant potential boundary condition that results in multibody effects in the electric double-layer interaction that are either absent or are very small in the familiar constant potential or constant charge or surface electrochemical equilibrium condition.

Tensor polarization of the ϕ meson photoproduced at high t

NASA Astrophysics Data System (ADS)

McCormick, K.; Audit, G.; Laget, J. M.; Adams, G.; Ambrozewicz, P.; Anciant, E.; Anghinolfi, M.; Asavapibhop, B.; Auger, T.; Avakian, H.; Bagdasaryan, H.; Ball, J. P.; Barrow, S.; Battaglieri, M.; Beard, K.; Bektasoglu, M.; Bellis, M.; Benmouna, N.; Berman, B. L.; Bianchi, N.; Biselli, A. S.; Boiarinov, S.; Bonner, B. E.; Bouchigny, S.; Bradford, R.; Brooks, W. K.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Carman, D. S.; Carnahan, B.; Cetina, C.; Chen, S.; Cole, P. L.; Coleman, A.; Connelly, J.; Cords, D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Cummings, J. P.; de Sanctis, E.; Devita, R.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Dharmawardane, K. V.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dragovitsch, P.; Dugger, M.; Dytman, S.; Dzyubak, O. P.; Eckhause, M.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Eugenio, P.; Farhi, L.; Feuerbach, R. J.; Ficenec, J.; Forest, T. A.; Frolov, V.; Funsten, H.; Gaff, S. J.; Gai, M.; Garçon, M.; Gavalian, G.; Gilad, S.; Gilfoyle, G. P.; Giovanetti, K. L.; Girard, P.; Gordon, C. I.; Griffioen, K.; Guidal, M.; Guillo, M.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hakobyan, R. S.; Hancock, D.; Hardie, J.; Heddle, D.; Hersman, F. W.; Hicks, K.; Hicks, R. S.; Holtrop, M.; Hyde-Wright, C. E.; Ito, M. M.; Jenkins, D.; Joo, K.; Juengst, H. G.; Kelley, J. H.; Khandaker, M.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A.; Klusman, M.; Kossov, M.; Kramer, L. H.; Kuang, Y.; Kuhn, S. E.; Kuhn, J.; Lachniet, J.; Langheinrich, J.; Lawrence, D.; Li, Ji; Lukashin, K.; Major, W.; Manak, J. J.; Marchand, C.; McAleer, S.; McNabb, J. W.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Minehart, R.; Mirazita, M.; Miskimen, R.; Morand, L.; Morrow, S. A.; Muccifora, V.; Mueller, J.; Mutchler, G. S.; Napolitano, J.; Nasseripour, R.; Nelson, S. O.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niyazov, R. A.; Nozar, M.; Osipenko, M.; Park, K.; Pasyuk, E.; Peterson, G.; Philips, S. A.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Qin, L. M.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rossi, P.; Rowntree, D.; Rubin, P. D.; Sabatié, F.; Sabourov, K.; Salgado, C.; Santoro, J. P.; Sanzone-Arenhovel, M.; Sapunenko, V.; Sargsyan, M.; Schumacher, R. A.; Serov, V. S.; Shafi, A.; Sharabian, Y. G.; Shaw, J.; Skabelin, A. V.; Smith, E. S.; Smith, T.; Smith, L. C.; Sober, D. I.; Spraker, M.; Stepanyan, S.; Stoler, P.; Strauch, S.; Taiuti, M.; Taylor, S.; Tedeschi, D. J.; Thoma, U.; Thompson, R.; Todor, L.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Wang, K.; Weinstein, L. B.; Weller, H.; Weygand, D. P.; Whisnant, C. S.; Witkowski, M.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yun, J.; Zhao, J.; Zhou, Z.

2004-03-01

As part of a measurement [

Length-dependence of intramolecular electron transfer in σ-bonded rigid molecular rods: an ab initio molecular orbital study

NASA Astrophysics Data System (ADS)

Pati, Ranjit; Karna, Shashi P.

2002-01-01

The dependence of electron transfer (ET) coupling element, VAB, on the length of rigid-rod-like systems consisting of bicyclo[1.1.1]pentane (BCP), cubane (CUB), and bicyclo[2.2.2]octane (BCO) monomers, has been investigated with the use of ab initio Hartree-Fock (HF) method employing Marcus-Hush two-state (TS) model. The value of VAB decreases exponentially with increase in the number of the cage units of the σ-bonded molecules. The calculated decay constant, β, shows good agreement with previously reported data. For molecular length⩾15 Å, the value of VAB becomes negligibly small, suggesting complete suppression of the through bond direct tunneling contribution to ET process.

Effective field theory search for high-energy nuclear recoils using the XENON100 dark matter detector

NASA Astrophysics Data System (ADS)

Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Manfredini, A.; Maris, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morâ, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Pizzella, V.; Piro, M.-C.; Plante, G.; Priel, N.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rosendahl, S.; Rupp, N.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Wang, H.; Wang, Z.; Wei, Y.; Weinheimer, C.; Wulf, J.; Ye, J.; Zhang., Y.; Farmer, B.; Xenon Collaboration

2017-08-01

We report on weakly interacting massive particles (WIMPs) search results in the XENON100 detector using a nonrelativistic effective field theory approach. The data from science run II (34 kg ×224.6 live days) were reanalyzed, with an increased recoil energy interval compared to previous analyses, ranging from (6.6 -240 ) keVnr . The data are found to be compatible with the background-only hypothesis. We present 90% confidence level exclusion limits on the coupling constants of WIMP-nucleon effective operators using a binned profile likelihood method. We also consider the case of inelastic WIMP scattering, where incident WIMPs may up-scatter to a higher mass state, and set exclusion limits on this model as well.

Pure wurtzite GaP nanowires grown on zincblende GaP substrates by selective area vapor liquid solid epitaxy

NASA Astrophysics Data System (ADS)

Halder, Nripendra N.; Kelrich, Alexander; Cohen, Shimon; Ritter, Dan

2017-11-01

We report on the growth of single phase wurtzite (WZ) GaP nanowires (NWs) on GaP (111) B substrates by metal organic molecular beam epitaxy following the selective area vapor-liquid-solid (SA-VLS) approach. During the SA-VLS process, precursors are supplied directly to the NW sidewalls, and the short diffusion length of gallium (or its precursors) does not significantly limit axial growth. Transmission electron microscopy (TEM) images reveal that no stacking faults are present along a 600 nm long NW. The lattice constants of the pure WZ GaP obtained from the TEM images agree with values determined previously by x-ray diffraction from non-pure NW ensembles.

Pure wurtzite GaP nanowires grown on zincblende GaP substrates by selective area vapor liquid solid epitaxy.

PubMed

Halder, Nripendra N; Kelrich, Alexander; Cohen, Shimon; Ritter, Dan

2017-11-17

We report on the growth of single phase wurtzite (WZ) GaP nanowires (NWs) on GaP (111) B substrates by metal organic molecular beam epitaxy following the selective area vapor-liquid-solid (SA-VLS) approach. During the SA-VLS process, precursors are supplied directly to the NW sidewalls, and the short diffusion length of gallium (or its precursors) does not significantly limit axial growth. Transmission electron microscopy (TEM) images reveal that no stacking faults are present along a 600 nm long NW. The lattice constants of the pure WZ GaP obtained from the TEM images agree with values determined previously by x-ray diffraction from non-pure NW ensembles.

The View From the Bottom: Relative Deprivation and Bullying Victimization in Canadian Adolescents.

PubMed

Napoletano, Anthony; Elgar, Frank J; Saul, Grace; Dirks, Melanie; Craig, Wendy

2016-12-01

We investigated the relation between relative deprivation (RD)-disparity in affluence between adolescents and their more affluent schoolmates-and involvement in bullying among 23,383 students (aged 9-19) in 413 schools that participated in the 2010 Canadian Health Behavior in School-Aged Children survey. Students reported family affluence and frequency of bullying victimization and perpetration during the previous 2 months. Using the Yitzhaki index of RD and multinomial logistic regression analysis, we found that RD positively related to three types of bullying victimization (physical, relational, and cyberbullying) and to two types of perpetration (relational and cyberbullying) after differences in absolute affluence were held constant. These findings suggest that RD uniquely contributes to risk of bullying involvement. © The Author(s) 2015.

Stable Causal Relationships Are Better Causal Relationships.

PubMed

Vasilyeva, Nadya; Blanchard, Thomas; Lombrozo, Tania

2018-05-01

We report three experiments investigating whether people's judgments about causal relationships are sensitive to the robustness or stability of such relationships across a range of background circumstances. In Experiment 1, we demonstrate that people are more willing to endorse causal and explanatory claims based on stable (as opposed to unstable) relationships, even when the overall causal strength of the relationship is held constant. In Experiment 2, we show that this effect is not driven by a causal generalization's actual scope of application. In Experiment 3, we offer evidence that stable causal relationships may be seen as better guides to action. Collectively, these experiments document a previously underappreciated factor that shapes people's causal reasoning: the stability of the causal relationship. Copyright © 2018 Cognitive Science Society, Inc.

Integrating the older/special needs adoptive child into the family.

PubMed

Clark, Pamela; Thigpen, Sally; Yates, Amy Moeller

2006-04-01

This qualitative, grounded theory study investigated 11 families who reported having successfully integrated into their family unit at least one older/special needs adoptee. The theory that emerged through the constant comparative methodology consisted of two categories (Decision to Adopt and Adjustment) and a core category (Developing a Sense of Family). The two categories and core category comprised a process that was informed by the Family Narrative Paradigm and culminated in the successful integration of the child or children into the existing family unit. Parental perceptions that appeared to facilitate this process included: (a) finding strengths in the children overlooked by previous caregivers, (b) viewing behavior in context, (c) reframing negative behavior, and (d) attributing improvement in behavior to parenting efforts.

Electronic, phonon and superconducting properties of LaPtBi half-Heusler compound

NASA Astrophysics Data System (ADS)

Shrivastava, Deepika; Sanyal, Sankar P.

2018-05-01

In the framework of density functional theory based on plane wave pseudopotential method and linear response technique, we have studied the electronic, phonon and superconducting properties of LaPtBi half-Heusler compound. The electronic band structure and density of states show that it is gapless semiconductor which is consistent with previous results. The positive phonon frequencies confirm the stability of this compound in cubic MgAgAs phase. Superconductivity is studied in terms of Eliashberg spectral function (α2F(ω)), electron-phonon coupling constants (λ). The value of electron-phonon coupling parameter is found to be 0.41 and the superconducting transition temperature is calculated to be 0.76 K, in excellent agreement with the experimentally reported values.

Low NO Concentration Dependence of Reductive Nitrosylation Reaction of Hemoglobin*

PubMed Central

Tejero, Jesús; Basu, Swati; Helms, Christine; Hogg, Neil; King, S. Bruce; Kim-Shapiro, Daniel B.; Gladwin, Mark T.

2012-01-01

The reductive nitrosylation of ferric (met)hemoglobin is of considerable interest and remains incompletely explained. We have previously observed that at low NO concentrations the reaction with tetrameric hemoglobin occurs with an observed rate constant that is at least 5 times faster than that observed at higher concentrations. This was ascribed to a faster reaction of NO with a methemoglobin-nitrite complex. We now report detailed studies of this reaction of low NO with methemoglobin. Nitric oxide paradoxically reacts with ferric hemoglobin with faster observed rate constants at the lower NO concentration in a manner that is not affected by changes in nitrite concentration, suggesting that it is not a competition between NO and nitrite, as we previously hypothesized. By evaluation of the fast reaction in the presence of allosteric effectors and isolated β- and α-chains of hemoglobin, it appears that NO reacts with a subpopulation of β-subunit ferric hemes whose population is influenced by quaternary state, redox potential, and hemoglobin dimerization. To further characterize the role of nitrite, we developed a system that oxidizes nitrite to nitrate to eliminate nitrite contamination. Removal of nitrite does not alter reaction kinetics, but modulates reaction products, with a decrease in the formation of S-nitrosothiols. These results are consistent with the formation of NO2/N2O3 in the presence of nitrite. The observed fast reductive nitrosylation observed at low NO concentrations may function to preserve NO bioactivity via primary oxidation of NO to form nitrite or in the presence of nitrite to form N2O3 and S-nitrosothiols. PMID:22493289

Primary care-led commissioning and public involvement in the English National Health Service. Lessons from the past.

PubMed

Petsoulas, Christina; Peckham, Stephen; Smiddy, Jane; Wilson, Patricia

2015-05-01

Patient and Public involvement (PPI) in health care occupies a central place in Western democracies. In England, this theme has been continuously prominent since the introduction of market reforms in the early 1990s. The health care reforms implemented by the current Coalition Government are making primary care practitioners the main commissioners of health care services in the National Health Service, and a duty is placed on them to involve the public in commissioning decisions and strategies. Since implementation of PPI initiatives in primary care commissioning is not new, we asked how likely it is that the new reforms will make a difference. We scanned the main literature related to primary care-led commissioning and found little evidence of effective PPI thus far. We suggest that unless the scope and intended objectives of PPI are clarified and appropriate resources are devoted to it, PPI will continue to remain empty rhetoric and box ticking. To examine the effect of previous PPI initiatives on health care commissioning and draw lessons for future development. We scanned the literature reporting on previous PPI initiatives in primary care-led commissioning since the introduction of the internal market in 1991. In particular, we looked for specific contexts, methods and outcomes of such initiatives. 1. PPI in commissioning has been constantly encouraged by policy makers in England. 2. Research shows limited evidence of effective methods and outcomes so far. 3. Constant reconfiguration of health care structures has had a negative impact on PPI. 4. The new structures look hardly better poised to bring about effective public and patient involvement.

Engineered Human Antibody Constant Domains with Increased Stability*S⃞

PubMed Central

Gong, Rui; Vu, Bang K.; Feng, Yang; Prieto, DaRue A.; Dyba, Marzena A.; Walsh, Joseph D.; Prabakaran, Ponraj; Veenstra, Timothy D.; Tarasov, Sergey G.; Ishima, Rieko; Dimitrov, Dimiter S.

2009-01-01

The immunoglobulin (Ig) constant CH2 domain is critical for antibody effector functions. Isolated CH2 domains are promising as scaffolds for construction of libraries containing diverse binders that could also confer some effector functions. However, previous work has shown that an isolated murine CH2 domain is relatively unstable to thermally induced unfolding. To explore unfolding mechanisms of isolated human CH2 and increase its stability γ1 CH2 was cloned and a panel of cysteine mutants was constructed. Human γ1 CH2 unfolded at a higher temperature (Tm = 54.1 °C, as measured by circular dichroism) than that previously reported for a mouse CH2 (41 °C). One mutant (m01) was remarkably stable (Tm = 73.8 °C). Similar results were obtained by differential scanning calorimetry. This mutant was also significantly more stable than the wild-type CH2 against urea induced unfolding (50% unfolding at urea concentration of 6.8 m versus 4.2 m). The m01 was highly soluble and monomeric. The existence of the second disulfide bond in m01 and its correct position were demonstrated by mass spectrometry and nuclear magnetic resonance spectroscopy, respectively. The loops were on average more flexible than the framework in both CH2 and m01, and the overall secondary structure was not affected by the additional disulfide bond. These data suggest that a human CH2 domain is relatively stable to unfolding at physiological temperature, and that both CH2 and the highly stable mutant m01 are promising new scaffolds for the development of therapeutics against human diseases. PMID:19307178

Seawater 234U/238U recorded by modern and fossil corals

NASA Astrophysics Data System (ADS)

Chutcharavan, Peter M.; Dutton, Andrea; Ellwood, Michael J.

2018-03-01

U-series dating of corals is a crucial tool for generating absolute chronologies of Late Quaternary sea-level change and calibrating the radiocarbon timescale. Unfortunately, coralline aragonite is susceptible to post-depositional alteration of its primary geochemistry. One screening technique used to identify unaltered corals relies on the back-calculation of initial 234U/238U activity (δ234Ui) at the time of coral growth and implicitly assumes that seawater δ234U has remained constant during the Late Quaternary. Here, we test this assumption using the most comprehensive compilation to date of coral U-series measurements. Unlike previous compilations, this study normalizes U-series measurements to the same decay constants and corrects for offsets in interlaboratory calibrations, thus reducing systematic biases between reported δ234U values. Using this approach, we reassess (a) the value of modern seawater δ234U, and (b) the evolution of seawater δ234U over the last deglaciation. Modern coral δ234U values (145.0 ± 1.5‰) agree with previous measurements of seawater and modern corals only once the data have been normalized. Additionally, fossil corals in the surface ocean display δ234Ui values that are ∼5-7‰ lower during the last glacial maximum regardless of site, taxon, or diagenetic setting. We conclude that physical weathering of U-bearing minerals exposed during ice sheet retreat drives the increase in δ234U observed in the oceans, a mechanism that is consistent with the interpretation of the seawater Pb-isotope signal over the same timescale.

Kinetic Parameters for the Noncatalyzed and Enzyme-Catalyzed Mutarotation of Glucose Using a Blood Glucometer

ERIC Educational Resources Information Center

Hardee, John R.; Delgado, Bryan; Jones, Wray

2011-01-01

The kinetic parameters for the conversion of alpha-D-glucose to beta-D-glucose were measured using a blood glucometer. The reaction order, rate constant, and Arrhenius activation energy are reported for the noncatalyzed reaction and turnover number and Michaelis constant are reported for the reaction catalyzed by porcine kidney mutarotase. The…

Mussel-inspired histidine-based transient network metal coordination hydrogels

PubMed Central

Fullenkamp, Dominic E.; He, Lihong; Barrett, Devin G.; Burghardt, Wesley R.; Messersmith, Phillip B.

2013-01-01

Transient network hydrogels cross-linked through histidine-divalent cation coordination bonds were studied by conventional rheologic methods using histidine-modified star poly(ethylene glycol) (PEG) polymers. These materials were inspired by the mussel, which is thought to use histidine-metal coordination bonds to impart self-healing properties in the mussel byssal thread. Hydrogel viscoelastic mechanical properties were studied as a function of metal, pH, concentration, and ionic strength. The equilibrium metal-binding constants were determined by dilute solution potentiometric titration of monofunctional histidine-modified methoxy-PEG and were found to be consistent with binding constants of small molecule analogs previously studied. pH-dependent speciation curves were then calculated using the equilibrium constants determined by potentiometric titration, providing insight into the pH dependence of histidine-metal ion coordination and guiding the design of metal coordination hydrogels. Gel relaxation dynamics were found to be uncorrelated with the equilibrium constants measured, but were correlated to the expected coordination bond dissociation rate constants. PMID:23441102

Dielectric constant extraction of graphene nanostructured on SiC substrates from spectroscopy ellipsometry measurement using Gauss–Newton inversion method

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

Maulina, Hervin; Santoso, Iman, E-mail: iman.santoso@ugm.ac.id; Subama, Emmistasega

2016-04-19

The extraction of the dielectric constant of nanostructured graphene on SiC substrates from spectroscopy ellipsometry measurement using the Gauss-Newton inversion (GNI) method has been done. This study aims to calculate the dielectric constant and refractive index of graphene by extracting the value of ψ and Δ from the spectroscopy ellipsometry measurement using GNI method and comparing them with previous result which was extracted using Drude-Lorentz (DL) model. The results show that GNI method can be used to calculate the dielectric constant and refractive index of nanostructured graphene on SiC substratesmore faster as compared to DL model. Moreover, the imaginary partmore » of the dielectric constant values and coefficient of extinction drastically increases at 4.5 eV similar to that of extracted using known DL fitting. The increase is known due to the process of interband transition and the interaction between the electrons and electron-hole at M-points in the Brillouin zone of graphene.« less

Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

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

Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de; Yachmenev, Andrey

2015-12-28

We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in verymore » good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.« less

Temperature dependent lattice constant of InSb above room temperature

NASA Astrophysics Data System (ADS)

Breivik, Magnus; Nilsen, Tron Arne; Fimland, Bjørn-Ove

2013-10-01

Using temperature dependent X-ray diffraction on two InSb single crystalline substrates, the bulk lattice constant of InSb was determined between 32 and 325 °C. A polynomial function was fitted to the data: a(T)=6.4791+3.28×10-5×T+1.02×10-8×T2 Å (T in °C), which gives slightly higher values than previously published (which go up to 62 °C). From the fit, the thermal expansion of InSb was calculated to be α(T)=5.062×10-6+3.15×10-9×T K-1 (T in °C). We found that the thermal expansion coefficient is higher than previously published values above 100 °C (more than 10% higher at 325 °C).

Terahertz laser vibration-rotation-tunneling spectrum of the water pentamer-d 10. . Constraints on the bifurcation tunneling dynamics

NASA Astrophysics Data System (ADS)

Cruzan, Jeff D.; Viant, Mark R.; Brown, Mac G.; Lucas, Don D.; Liu, Kun; Saykally, Richard J.

1998-08-01

The vibration-rotation-tunneling (VRT) spectrum of a low-frequency intermolecular vibration of (D 2O) 5 was recorded near 0.9 THz (30.2 cm -1). From an analysis of the relative intensities in the compact Q-branch region, the ground-state C-rotational constant is estimated to be 975±60 MHz, consistent with ab initio structural predictions. The precisely determined B-rotational constant ( B=1750.96±0.20 MHz) agrees well with previous results. Efforts to resolve possible bifurcation tunneling fine structure, such as that observed in VRT spectra of (D 2O) 3, revealed no such effects. This constrains the splittings to be less than 450 kHz, or roughly 3 times smaller than required by previous results.

Measurement of the Decay Constant fDs+ Using Ds+→l+ν

NASA Astrophysics Data System (ADS)

Artuso, M.; Blusk, S.; Butt, J.; Khalil, S.; Li, J.; Menaa, N.; Mountain, R.; Nisar, S.; Randrianarivony, K.; Sia, R.; Skwarnicki, T.; Stone, S.; Wang, J. C.; Bonvicini, G.; Cinabro, D.; Dubrovin, M.; Lincoln, A.; Asner, D. M.; Edwards, K. W.; Naik, P.; Briere, R. A.; Ferguson, T.; Tatishvili, G.; Vogel, H.; Watkins, M. E.; Rosner, J. L.; Adam, N. E.; Alexander, J. P.; Cassel, D. G.; Duboscq, J. E.; Ehrlich, R.; Fields, L.; Gibbons, L.; Gray, R.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hertz, D.; Jones, C. D.; Kandaswamy, J.; Kreinick, D. L.; Kuznetsov, V. E.; Mahlke-Krüger, H.; Mohapatra, D.; Onyisi, P. U. E.; Patterson, J. R.; Peterson, D.; Pivarski, J.; Riley, D.; Ryd, A.; Sadoff, A. J.; Schwarthoff, H.; Shi, X.; Stroiney, S.; Sun, W. M.; Wilksen, T.; Athar, S. B.; Patel, R.; Yelton, J.; Rubin, P.; Cawlfield, C.; Eisenstein, B. I.; Karliner, I.; Kim, D.; Lowrey, N.; Selen, M.; White, E. J.; Wiss, J.; Mitchell, R. E.; Shepherd, M. R.; Besson, D.; Pedlar, T. K.; Cronin-Hennessy, D.; Gao, K. Y.; Hietala, J.; Kubota, Y.; Klein, T.; Lang, B. W.; Poling, R.; Scott, A. W.; Smith, A.; Zweber, P.; Dobbs, S.; Metreveli, Z.; Seth, K. K.; Tomaradze, A.; Ernst, J.; Ecklund, K. M.; Severini, H.; Love, W.; Savinov, V.; Aquines, O.; Lopez, A.; Mehrabyan, S.; Mendez, H.; Ramirez, J.; Huang, G. S.; Miller, D. H.; Pavlunin, V.; Sanghi, B.; Shipsey, I. P. J.; Xin, B.; Adams, G. S.; Anderson, M.; Cummings, J. P.; Danko, I.; Hu, D.; Moziak, B.; Napolitano, J.; He, Q.; Insler, J.; Muramatsu, H.; Park, C. S.; Thorndike, E. H.; Yang, F.

2007-08-01

We measure the decay constant fDs+ using the Ds+→ℓ+ν channel, where the ℓ+ designates either a μ+ or a τ+, when the τ+→π+ν¯. Using both measurements we find fDs+=274±13±7MeV. Combining with our previous determination of fD+, we compute the ratio fDs+/fD+=1.23±0.11±0.04. We compare with theoretical estimates.

Visible-light promoted catalytic activity of dumbbell-like Au nanorods supported on graphene/TiO2 sheets towards hydrogenation reaction.

PubMed

Dai, Yunqian; Zhu, Mingyun; Wang, Xiaotian; Wu, Yanan; Huang, Chengqian; Fu, Wanlin; Meng, Xiangyu; Sun, Yueming

2018-06-15

In this work, the rationally-designed sharp corners on Au nanorods tremendously improved the catalytic activity, particularly in the presence of visible light irradiation, towards the hydrogenation of 4-nitrophenol to 4-aminophenol. A strikingly increased rate constant of 50.6 g -1 s -1 L was achieved in M-Au-3, which was 41.8 times higher than that of parent Au nanorods under dark conditions. The enhanced activities were proportional to the extent of the protruding sharp corners. Furthermore, remarkably enhanced activities were achieved in novel ternary Au/RGO/TiO 2 sheets, which were endowed with a 52.0 times higher rate constant than that of straight Au nanorods. These remarkably enhanced activities were even higher than those of previously reported 3-5 nm Au and 3 nm Pt nanoparticles. It was systematically observed that there are three aspects to the synergistic effects between Au and RGO sheets: (i) electron transfer from RGO to Au, (ii) a high concentration of p-nitrophenol close to dumbbell-like Au nanorods on RGO sheets, and (iii) increased local reaction temperature from the photothermal effect of both dumbbell-like Au nanorods and RGO sheets.

Revised Parameters for the AMOEBA Polarizable Atomic Multipole Water Model.

PubMed

Laury, Marie L; Wang, Lee-Ping; Pande, Vijay S; Head-Gordon, Teresa; Ponder, Jay W

2015-07-23

A set of improved parameters for the AMOEBA polarizable atomic multipole water model is developed. An automated procedure, ForceBalance, is used to adjust model parameters to enforce agreement with ab initio-derived results for water clusters and experimental data for a variety of liquid phase properties across a broad temperature range. The values reported here for the new AMOEBA14 water model represent a substantial improvement over the previous AMOEBA03 model. The AMOEBA14 model accurately predicts the temperature of maximum density and qualitatively matches the experimental density curve across temperatures from 249 to 373 K. Excellent agreement is observed for the AMOEBA14 model in comparison to experimental properties as a function of temperature, including the second virial coefficient, enthalpy of vaporization, isothermal compressibility, thermal expansion coefficient, and dielectric constant. The viscosity, self-diffusion constant, and surface tension are also well reproduced. In comparison to high-level ab initio results for clusters of 2-20 water molecules, the AMOEBA14 model yields results similar to AMOEBA03 and the direct polarization iAMOEBA models. With advances in computing power, calibration data, and optimization techniques, we recommend the use of the AMOEBA14 water model for future studies employing a polarizable water model.

Capillary Flow in an Interior Corner

NASA Technical Reports Server (NTRS)

Weislogel, Mark Milton

1996-01-01

The design of fluids management processes in the low-gravity environment of space requires an accurate model and description of capillarity-controlled flow in containers of irregular geometry. Here we consider the capillary rise of a fluid along an interior corner of a container following a rapid reduction in gravity. The analytical portion of the work presents an asymptotic formulation in the limit of a slender fluid column, slight surface curvature along the corner, small inertia, and low gravity. New similarity solutions are found and a list of closed form expressions is provided for flow rate and column length. In particular, it is found that the flow is proportional to t(exp 1/2) for a constant height boundary condition, t(exp 2/5) for a spreading drop, and t(exp 3/5) for constant flow. In the experimental portion of the work, measurements from a 2.2s drop tower are reported. An extensive data set, collected over a previously unexplored range of flow parameters, includes estimates of repeatability and accuracy, the role of inertia and column slenderness, and the effects of corner angle, container geometry, and fluid properties. Comprehensive comparisons are made which illustrate the applicability of the analytic results to low-g fluid systems design.

Elongated Tetrakaidecahedron Micromechanics Model for Space Shuttle External Tank Foams

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.; Ghosn, Louis J.; Lerch, Bradley A.; Baker, Eric H.

2009-01-01

The results of microstructural characterization studies and physical and mechanical testing of BX-265 and NCFI24-124 foams are reported. A micromechanics model developed previously by the authors is reviewed, and the resulting equations for the elastic constants, the relative density, and the strength of the foam in the principal material directions are presented. The micromechanics model is also used to derive equations to predict the effect of vacuum on the tensile strength and the strains induced by exposure to vacuum. Using a combination of microstructural dimensions and physical and mechanical measurements as input, the equations for the elastic constants and the relative density are applied and the remaining microstructural dimensions are predicted. The predicted microstructural dimensions are in close agreement with the average measured values for both BX-265 and NCFI24-124. With the microstructural dimensions, the model predicts the ratio of the strengths in the principal material directions for both foams. The model is also used to predict the Poisson s ratios, the vacuum-induced strains, and the effect of vacuum on the tensile strengths. However, the comparison of these predicted values with the measured values is not as favorable.

Capture of shrinking targets with realistic shrink patterns.

PubMed

Hoffmann, Errol R; Chan, Alan H S; Dizmen, Coskun

2013-01-01

Previous research [Hoffmann, E. R. 2011. "Capture of Shrinking Targets." Ergonomics 54 (6): 519-530] reported experiments for capture of shrinking targets where the target decreased in size at a uniform rate. This work extended this research for targets having a shrink-size versus time pattern that of an aircraft receding from an observer. In Experiment 1, the time to capture the target in this case was well correlated in terms of Fitts' index of difficulty, measured at the time of capture of the target, a result that is in agreement with the 'balanced' model of Johnson and Hart [Johnson, W. W., and Hart, S. G. 1987. "Step Tracking Shrinking Targets." Proceedings of the human factors society 31st annual meeting, New York City, October 1987, 248-252]. Experiment 2 measured the probability of target capture for varying initial target sizes and target shrink rates constant, defined as the time for the target to shrink to half its initial size. Data of shrink time constant for 50% probability of capture were related to initial target size but did not greatly affect target capture as the rate of target shrinking decreased rapidly with time.

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

Han, Chao; Lignell, David O.; Hawkes, Evatt R.

Here, the effect of differential molecular diffusion (DMD) in turbulent non-premixed flames is studied by examining two previously reported DNS of temporally evolving planar jet flames, one with CO/H 2 as the fuel and the other with C 2H 4 as the fuel. The effect of DMD in the CO/H 2 DNS flames in which H 2 is part of fuel is found to behave similar to laminar flamelet, while in the C 2H 4 DNS flames in which H 2 is not present in the fuel it is similar to laminar flamelet in early stages but becomes different frommore » laminar flamelet later. The scaling of the effect of DMD with respect to the Reynolds number Re is investigated in the CO/H 2 DNS flames, and an evident power law scaling (~Re –a with a a positive constant) is observed. The scaling of the effect of DMD with respect to the Damkohler number Da is explored in both laminar counter-flow jet C 2H 4 diffusion flames and the C 2H 4 DNS flames. A power law scaling (~ Daa with a a positive constant) is clearly demonstrated for C 2H 4 nonpremixed flames.« less

Anticancer drug-DNA interactions measured using a photoinduced electron-transfer mechanism based on luminescent quantum dots.

PubMed

Yuan, Jipei; Guo, Weiwei; Yang, Xiurong; Wang, Erkang

2009-01-01

A sensing system based on the photoinduced electron transfer of quantum dots (QDs) was designed to measure the interaction of anticancer drug and DNA, taking mitoxantrone (MTX) as a model drug. MTX adsorbed on the surface of QDs can quench the photoluminescence (PL) of QDs through the photoinduced electron-transfer process; and then the addition of DNA will bring the restoration of QDs PL intensity, as DNA can bind with MTX and remove it from QDs. Sensitive detection of MTX with the detection limit of 10 nmol L(-1) and a linear detection range from 10 nmol L(-1) to 4.5 micromol L(-1) was achieved. The dependence of PL intensity on DNA amount was successfully utilized to investigate the interactions between MTX and DNA. Both the binding constants and the sizes of binding site of MTX-DNA interactions were calculated based on the equations deduced for the PL recovery process. The binding constant obtained in our experiment was generally consistent with previous reports. The sensitive and speedy detection of MTX as well as the avoidance of modification or immobilization process made this system suitable and promising in the drug-DNA interaction studies.

Sonneberg Plate Photometry for Boyajian’s Star in Two Passbands

NASA Astrophysics Data System (ADS)

Hippke, Michael; Kroll, Peter; Matthai, Frank; Angerhausen, Daniel; Tuvikene, Taavi; Stassun, Keivan G.; Roshchina, Elena; Vasileva, Tatyana; Izmailov, Igor; Samus, Nikolay N.; Pastukhova, Elena N.; Bryukhanov, Ivan; Lund, Michael B.

2017-03-01

The F3 main-sequence star KIC 8462852 (Boyajian’s Star) showed deep (up to 20%) day-long brightness dips of unknown cause during the four years of the Kepler mission. A 0.164 mag (16%) dimming between 1890 and 1990 was claimed, based on the analysis of photographic plates from the Harvard Observatory. We have gathered an independent set of historic plates from Sonneberg Observatory, Germany, covering the years of 1934-1995. With 861 mag in B, and 397 mag in V, we find the star to be of constant brightness within 0.03 mag per century (3%). Consistent outcomes are found using by-eye estimates of the best 119 plates. Results are supported by data from Sternberg Observatory, Moscow, which show the star as constant between 1895 and 1995. The previously claimed century-long dimming is inconsistent with our results at the 5σ -level, however, the recently reported modest dimming of 3% in the Kepler data is not inconsistent with our data. We find no periodicities or shorter trends within our limits of 5% per five year bin, but note a possible dimming event on 1978 October 24.

Visible-light promoted catalytic activity of dumbbell-like Au nanorods supported on graphene/TiO2 sheets towards hydrogenation reaction

NASA Astrophysics Data System (ADS)

Dai, Yunqian; Zhu, Mingyun; Wang, Xiaotian; Wu, Yanan; Huang, Chengqian; Fu, Wanlin; Meng, Xiangyu; Sun, Yueming

2018-06-01

In this work, the rationally-designed sharp corners on Au nanorods tremendously improved the catalytic activity, particularly in the presence of visible light irradiation, towards the hydrogenation of 4-nitrophenol to 4-aminophenol. A strikingly increased rate constant of 50.6 g‑1 s‑1 L was achieved in M-Au-3, which was 41.8 times higher than that of parent Au nanorods under dark conditions. The enhanced activities were proportional to the extent of the protruding sharp corners. Furthermore, remarkably enhanced activities were achieved in novel ternary Au/RGO/TiO2 sheets, which were endowed with a 52.0 times higher rate constant than that of straight Au nanorods. These remarkably enhanced activities were even higher than those of previously reported 3–5 nm Au and 3 nm Pt nanoparticles. It was systematically observed that there are three aspects to the synergistic effects between Au and RGO sheets: (i) electron transfer from RGO to Au, (ii) a high concentration of p-nitrophenol close to dumbbell-like Au nanorods on RGO sheets, and (iii) increased local reaction temperature from the photothermal effect of both dumbbell-like Au nanorods and RGO sheets.

Electronic Polarizability and the Effective Pair Potentials of Water

PubMed Central

Leontyev, I. V.; Stuchebrukhov, A. A.

2014-01-01

Employing the continuum dielectric model for electronic polarizability, we have developed a new consistent procedure for parameterization of the effective nonpolarizable potential of liquid water. The model explains the striking difference between the value of water dipole moment μ~3D reported in recent ab initio and experimental studies with the value μeff~2.3D typically used in the empirical potentials, such as TIP3P or SPC/E. It is shown that the consistency of the parameterization scheme can be achieved if the magnitude of the effective dipole of water is understood as a scaled value μeff=μ∕εel, where εel =1.78 is the electronic (high-frequency) dielectric constant of water, and a new electronic polarization energy term, missing in the previous theories, is included. The new term is evaluated by using Kirkwood - Onsager theory. The new scheme is fully consistent with experimental data on enthalpy of vaporization, density, diffusion coefficient, and static dielectric constant. The new theoretical framework provides important insights into the nature of the effective parameters, which is crucial when the computational models of liquid water are used for simulations in different environments, such as proteins, or for interaction with solutes. PMID:25383062

An exact closed form solution for constant area compressible flow with friction and heat transfer

NASA Technical Reports Server (NTRS)

Sturas, J. I.

1971-01-01

The well-known differential equation for the one-dimensional flow of a compressible fluid with heat transfer and wall friction has no known solution in closed form for the general case. This report presents a closed form solution for the special case of constant heat flux per unit length and constant specific heat. The solution was obtained by choosing the square of a dimensionless flow parameter as one of the independent variables to describe the flow. From this exact solution, an approximate simplified form is derived that is applicable for predicting subsonic flow performance characteristics for many types of constant area passages in internal flow. The data included in this report are considered sufficiently accurate for use as a guide in analyzing and designing internal gas flow systems.

Superradiance of cold atoms coupled to a superconducting circuit

NASA Astrophysics Data System (ADS)

Braun, Daniel; Hoffman, Jonathan; Tiesinga, Eite

2011-06-01

We investigate superradiance of an ensemble of atoms coupled to an integrated superconducting LC circuit. Particular attention is paid to the effect of inhomogeneous coupling constants. Combining perturbation theory in the inhomogeneity and numerical simulations, we show that inhomogeneous coupling constants can significantly affect the superradiant relaxation process. Incomplete relaxation terminating in “dark states” can occur, from which the only escape is through individual spontaneous emission on a much longer time scale. The relaxation dynamics can be significantly accelerated or retarded, depending on the distribution of the coupling constants. On the technical side, we also generalize the previously known propagator of superradiance for identical couplings in the completely symmetric sector to the full exponentially large Hilbert space.

A Constant-Factor Approximation Algorithm for the Link Building Problem

NASA Astrophysics Data System (ADS)

Olsen, Martin; Viglas, Anastasios; Zvedeniouk, Ilia

In this work we consider the problem of maximizing the PageRank of a given target node in a graph by adding k new links. We consider the case that the new links must point to the given target node (backlinks). Previous work [7] shows that this problem has no fully polynomial time approximation schemes unless P = NP. We present a polynomial time algorithm yielding a PageRank value within a constant factor from the optimal. We also consider the naive algorithm where we choose backlinks from nodes with high PageRank values compared to the outdegree and show that the naive algorithm performs much worse on certain graphs compared to the constant factor approximation scheme.

Phases of a fermionic model with chiral condensates and Cooper pairs in 1+1 dimensions

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

Mihaila, Bogdan; Blagoev, Krastan B.; MIND Institute, Albuquerque, New Mexico 87131

2006-01-01

We study the phase structure of a 4-fermi model with three bare coupling constants, which potentially has three types of bound states. This model is a generalization of the model discussed previously by [A. Chodos, F. Cooper, W. Mao, H. Minakata, and A. Singh, Phys. Rev. D 61, 045011 (2000).], which contained both chiral condensates and Cooper pairs. For this generalization we find that there are two independent renormalized coupling constants which determine the phase structure at finite density and temperature. We find that the vacuum can be in one of three distinct phases depending on the value of thesemore » two renormalized coupling constants.« less

Constant load and constant volume response of municipal solid waste in simple shear.

PubMed

Zekkos, Dimitrios; Fei, Xunchang

2017-05-01

Constant load and constant volume simple shear testing was conducted on relatively fresh municipal solid waste (MSW) from two landfills in the United States, one in Michigan and a second in Texas, at respective natural moisture content below field capacity. The results were assessed in terms of two failure strain criteria, at 10% and 30% shear strain, and two interpretations of effective friction angle. Overall, friction angle obtained assuming that the failure plane is horizontal and at 10% shear strain resulted in a conservative estimation of shear strength of MSW. Comparisons between constant volume and constant load simple shear testing results indicated significant differences in the shear response of MSW with the shear resistance in constant volume being lower than the shear resistance in constant load. The majority of specimens were nearly uncompacted during specimen preparation to reproduce the state of MSW in bioreactor landfills or in uncontrolled waste dumps. The specimens had identical percentage of <20mm material but the type of <20mm material was different. The <20mm fraction from Texas was finer and of high plasticity. MSW from Texas was overall weaker in both constant load and constant volume conditions compared to Michigan waste. The results of these tests suggest the possibility of significantly lower shear strength of MSW in bioreactor landfills where waste is placed with low compaction effort and constant volume, i.e., "undrained", conditions may occur. Compacted MSW specimens resulted in shear strength parameters that are higher than uncompacted specimens and closer to values reported in the literature. However, the normalized undrained shear strength in simple shear for uncompacted and compacted MSW was still higher than the normalized undrained shear strength reported in the literature for clayey and silty soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reynolds stress scaling in pipe flow turbulence-first results from CICLoPE.

PubMed

Örlü, R; Fiorini, T; Segalini, A; Bellani, G; Talamelli, A; Alfredsson, P H

2017-03-13

This paper reports the first turbulence measurements performed in the Long Pipe Facility at the Center for International Cooperation in Long Pipe Experiments (CICLoPE). In particular, the Reynolds stress components obtained from a number of straight and boundary-layer-type single-wire and X-wire probes up to a friction Reynolds number of 3.8×10 4 are reported. In agreement with turbulent boundary-layer experiments as well as with results from the Superpipe, the present measurements show a clear logarithmic region in the streamwise variance profile, with a Townsend-Perry constant of A 2 ≈1.26. The wall-normal variance profile exhibits a Reynolds-number-independent plateau, while the spanwise component was found to obey a logarithmic scaling over a much wider wall-normal distance than the other two components, with a slope that is nearly half of that of the Townsend-Perry constant, i.e. A 2,w ≈A 2 /2. The present results therefore provide strong support for the scaling of the Reynolds stress tensor based on the attached-eddy hypothesis. Intriguingly, the wall-normal and spanwise components exhibit higher amplitudes than in previous studies, and therefore call for follow-up studies in CICLoPE, as well as other large-scale facilities.This article is part of the themed issue 'Toward the development of high-fidelity models of wall turbulence at large Reynolds number'. © 2017 The Author(s).

4-Hydroxyanisole: the most suitable monophenolic substrate for determining spectrophotometrically the monophenolase activity of polyphenol oxidase from fruits and vegetables.

PubMed

Espín, J C; Tudela, J; García-Cánovas, F

1998-05-15

A continuous spectrophotometric method for determining the monophenolase activity of polyphenol oxidase from several plant sources is described. This assay method is based on the coupling reaction between 3-methyl-2-benzothiazolinone hydrazone and the quinone product of the oxidation of 4-hydroxyanisole in the presence of polyphenol oxidase. 4-Hydroxyanisole proved to be the best monophenol assayed to measure the monophenolase activity of polyphenol oxidase from apple, artichoke, avocado, medlar, pear, and strawberry. Kinetic constants of 4-hydroxyanisole were compared to those of p-hydroxyphenyl propionic acid, a very sensitive monophenol previously reported to assay the monophenolase activity of polyphenol oxidase from apple, pear, and mushroom. The high values of the maximum steady state rate obtained for 4-hydroxyanisole suggest the existence of high catalytic constant toward this monophenol. These kinetic values were supported by nuclear magnetic resonance assays which predicted the highest reactivity of 4-hydroxyanisole. Therefore nuclear magnetic resonance assays proved to be a valuable and useful tool to predict the best monophenolic substrate for plant polyphenol oxidases. The 3-methyl-2-benzothiazlolinone-adduct for 4-hydroxyanisole was stable, with high molar absorptivity at the optimum pHs of the polyphenol oxidases assayed. All this together makes the use of 4-hydroxyanisol as monophenolic substrate and 3-methyl-2-benzothiazolinone as coupling reagent the most sensitive and precise assay method up to date reported in the literature to determine the monophenolas activity of polyphenol oxidase from fruits and vegetables.

Interfacial Reaction Studies Using ONIOM

NASA Technical Reports Server (NTRS)

Cardelino, Beatriz H.

2003-01-01

In this report, we focus on the calculations of the energetics and chemical kinetics of heterogeneous reactions for Organometallic vapor phase epitaxy (OMVPE). The work described in this report builds upon our own previous thermochemical and chemical kinetics studies. The first of these articles refers to the prediction of thermochemical properties, and the latter one deals with the prediction of rate constants for gaseous homolytic dissociation reactions. The calculations of this investigation are at the microscopic level. The systems chosen consisted of a gallium nitride (GaN) substrate, and molecular nitrogen (N2) and ammonia (NH3) as adsorbants. The energetics for the adsorption and the adsorbant dissociation processes were estimated, and reaction rate constants for the dissociation reactions of free and adsorbed molecules were predicted. The energetics for substrate decomposition was also computed. The ONIOM method, implemented in the Gaussian98 program, was used to perform the calculations. This approach has been selected since it allows dividing the system into two layers that can be treated at different levels of accuracy. The atoms of the substrate were modeled using molecular mechanics6 with universal force fields, whereas the adsorbed molecules were approximated using quantum mechanics, based on density functional theory methods with B3LYP functionals and 6-311G(d,p) basis sets. Calculations for the substrate were performed in slabs of several unit cells in each direction. The N2 and NH3 adsorbates were attached to a central location at the Ga-lined surface.

Application of the backstepping method to the prediction of increase or decrease of infected population.

PubMed

Kuniya, Toshikazu; Sano, Hideki

2016-05-10

In mathematical epidemiology, age-structured epidemic models have usually been formulated as the boundary-value problems of the partial differential equations. On the other hand, in engineering, the backstepping method has recently been developed and widely studied by many authors. Using the backstepping method, we obtained a boundary feedback control which plays the role of the threshold criteria for the prediction of increase or decrease of newly infected population. Under an assumption that the period of infectiousness is same for all infected individuals (that is, the recovery rate is given by the Dirac delta function multiplied by a sufficiently large positive constant), the prediction method is simplified to the comparison of the numbers of reported cases at the current and previous time steps. Our prediction method was applied to the reported cases per sentinel of influenza in Japan from 2006 to 2015 and its accuracy was 0.81 (404 correct predictions to the total 500 predictions). It was higher than that of the ARIMA models with different orders of the autoregressive part, differencing and moving-average process. In addition, a proposed method for the estimation of the number of reported cases, which is consistent with our prediction method, was better than that of the best-fitted ARIMA model ARIMA(1,1,0) in the sense of mean square error. Our prediction method based on the backstepping method can be simplified to the comparison of the numbers of reported cases of the current and previous time steps. In spite of its simplicity, it can provide a good prediction for the spread of influenza in Japan.

Johnson-McMillin syndrome, a neuroectodermal syndrome with conductive hearing loss and microtia: report of a new case.

PubMed

Schweitzer, Daniela N; Yano, Shoji; Earl, Dawn L; Graham, John M

2003-07-30

In 1983, Johnson et al. described 16 related individuals with alopecia, anosmia or hyposmia, conductive hearing loss, microtia and/or atresia of the external auditory canal, and hypogonadotrophic hypogonadism inherited in an autosomal dominant pattern. Other less constant manifestations included facial asymmetry, mental retardation, congenital heart defect, cleft palate, and choanal stenosis. An isolated case was reported later (Johnston et al. [1987: Am J Med Genet 26: 925-927]) and thereafter an affected mother and son (Hennekam and Holtus [1993: Am J Med Genet 47: 714-716]). We describe an additional unrelated female patient with features resembling those of the previously reported cases. She presented with intrauterine growth deficiency, microcephaly, alopecia, bilateral microtia with canal atresia, conductive hearing loss, partial left facial palsy, posterior cleft palate, left choanal stenosis, tetralogy of Fallot, developmental delay, and right thumb polydactyly. Because the phenotypic abnormalities in this syndrome affect the brain, facial structures, ectoderm and its derivatives, outflow tract of the heart, and Rathke's pouch derivatives, this has suggested to previous authors etiologic involvement of the ectoderm and neuroectoderm of the first and second branchial arches, Rathke's pouch, and the diencephalon. Microtia with conductive hearing loss differentiates the condition from other ectodermal dysplasias. In the initial report, females appeared somewhat less affected than males, and there was male-to-male transmission. The mother of our patient manifests subtle features, which suggest she may be a mildly affected female. Additionally, there is a family history of early-onset alopecia in the maternal grandfather's relatives. Copyright 2003 Wiley-Liss, Inc.

Imino proton exchange and base-pair kinetics in the AMP-RNA aptamer complex.

PubMed

Nonin, S; Jiang, F; Patel, D J

1997-05-02

We report on the dynamics of base-pair opening in the ATP-binding asymmetric internal loop and flanking base-pairs of the AMP-RNA aptamer complex by monitoring the exchange characteristics of the extremely well resolved imino protons in the NMR spectrum of the complex. The kinetics of imino proton exchange as a function of basic pH or added ammonia catalyst are used to measure the apparent base-pair dissociation constants and lifetimes of Watson-Crick and mismatched base-pairs, as well as the solvent accessibility of the unpaired imino protons in the complex. The exchange characteristics of the imino protons identify the existence of four additional hydrogen bonds stabilizing the conformation of the asymmetric ATP-binding internal loop that were not detected by NOEs and coupling constants alone, but are readily accommodated in the previously reported solution structure of the AMP-RNA aptamer complex published from our laboratory. The hydrogen exchange kinetics of the non-Watson-Crick pairs in the asymmetric internal loop of the AMP-RNA aptamer complex have been characterized and yield apparent dissociation constants (alphaKd) that range from 10(-2) to 10(-7). Surprisingly, three of these alphaKd values are amongst the lowest measured for all base-pairs in the AMP-RNA aptamer complex. Comparative studies of hydrogen exchange of the imino protons in the free RNA aptamer and the AMP-RNA aptamer complex establish that complexation stabilizes not only the bases within the ATP-binding asymmetric internal loop, but also the flanking stem base-pairs (two pairs on either side) of the binding site. We also outline some preliminary results related to the exchange properties of a sugar 2'-hydroxyl proton of a guanosine residue involved in a novel hydrogen bond that has been shown to contribute to the immobilization of the bound AMP by the RNA aptamer, and whose resonance is narrow and downfield shifted in the spectrum.

Near millimeter wave imaging/multi-beam integrated antennas

NASA Technical Reports Server (NTRS)

Yngvesson, K. S.; Schaubert, D. H.

1985-01-01

This report describes the most recent work on the theory of single element Linearly Tapered Slot Antennas (LTSAs) and Constant Width Slot Antennas (CWSAs). The radiation mechanism for these is presently well understood and allows quantitative calculation of beamwidths and sidelobe levels, provided that the antennas have a sufficiently wide conducting region on either side of the tapered slot. Appendices 4 to 7 represent earlier work on the grant. This work further elucidates the properties of arrays of CWSA elements, and the effects of coupling on the beam-shape. It should be noted that typical beam-efficiencies of 65% have been estimated, and that element spacings of about one Rayleigh unit are possible. Further, two-point resolution at the Rayleigh spacing has been demonstrated for a CWSA array in a 30.4 cm paraboloid at 31 GHz. These results underscore that interest in further studies of the radiation mechanism of tapered slot arrays. Appendix 7 constitutes a final, detailed report on the work leading to a 94 GHz seven element LTSA array imaging system, which has been reported previously in less detail. Experimental results are presented.

Cavity-enhanced measurements of hydrogen peroxide absorption cross sections from 353 to 410 nm.

PubMed

Kahan, Tara F; Washenfelder, Rebecca A; Vaida, Veronica; Brown, Steven S

2012-06-21

We report near-ultraviolet and visible absorption cross sections of hydrogen peroxide (H(2)O(2)) using incoherent broad-band cavity-enhanced absorption spectroscopy (IBBCEAS), a recently developed, high-sensitivity technique. The measurements reported here span the range of 353-410 nm and extend published electronic absorption cross sections by 60 nm to absorption cross sections below 1 × 10(-23) cm(2) molecule(-1). We have calculated photolysis rate constants for H(2)O(2) in the lower troposphere at a range of solar zenith angles by combining the new measurements with previously reported data at wavelengths shorter than 350 nm. We predict that photolysis at wavelengths longer than those included in the current JPL recommendation may account for up to 28% of the total hydroxyl radical (OH) production from H(2)O(2) photolysis under some conditions. Loss of H(2)O(2) via photolysis may be of the same order of magnitude as reaction with OH and dry deposition in the lower atmosphere; these processes have very different impacts on HO(x) loss and regeneration.

Ada (Trademark) Compiler Validation Summary Report: Certificate Number: 880714N1,09135, GEC Software Ltd, VADS Version 5.5, SUN 3/50 Workstation X GEC 4195 Minicomputer

DTIC Science & Technology

1988-07-15

floating-point accuracy that exceeds the maximum of 15 digits supported by this implementation: C24113L..Y (14 tests) C35705L..Y (14 tests) C35706L...declarative part or package specification, or after a libary unit in a compilation, but before any subsequent compilation unit. When the first argument is a...INT constant :=2147483647; MAX- DIGITS :constant :~15; MAX-MANTISSA constant 31; FINE-DELTA constant :=2.0’*(-31); TICK :constant :=0.01; -- Other

Rate constant for the reaction of atomic chlorine with methane

NASA Technical Reports Server (NTRS)

Lin, C. L.; Leu, M. T.; Demore, W. B.

1978-01-01

The rate constant and temperature dependence of the Cl + CH4 reaction have been investigated by the techniques of competitive chlorination of CH4/C2H6 mixtures and by discharge-flow/mass spectroscopy. The objectives were to determine an accurate value for the rate constant for use in stratospheric modeling, and to clarify discrepancies in results previously obtained by different techniques. The results deduced from the competitive chlorination study are in good agreement with the absolute values measured by the mass spectrometric method, and at temperatures above 300 K are in good agreement with measurements by other techniques based on resonance fluorescence detection of atomic chlorine. However, in the 220-300 K region, the competitive experiments indicate lower rate constants than those obtained by resonance fluorescence methods, and do not reproduce the curved Arrhenius plots seen in some of those studies.

An approach to the determination of aircraft handling qualities using pilot transfer functions

NASA Technical Reports Server (NTRS)

Adams, J. J.; Hatch, H. G., Jr.

1978-01-01

It was shown that a correlation exists between pilot-aircraft system closed-loop characteristics, determined by using analytical expressions for pilot response along with the analytical expression for the aircraft response, and pilot ratings obtained in many previous flight and simulation studies. Two different levels of preferred pilot response were used. These levels were: (1) a static gain and a second-order lag function with a lag time constant of 0.2 second; and (2) a static gain, a lead time constant of 1 second, and a 0.2-second lag time constant. If a system response with a pitch-angle time constant of 2.6 seconds and a stable oscillatory mode of motion with a period of 2.5 seconds could be achieved with the first-level pilot model, it was shown that the pilot rating will be satisfactory for that vehicle.

Catalytic oxidation of o-aminophenols and aromatic amines by mushroom tyrosinase.

PubMed

Muñoz-Muñoz, Jose Luis; Garcia-Molina, Francisco; Garcia-Ruiz, Pedro Antonio; Varon, Ramon; Tudela, Jose; Rodriguez-Lopez, Jose N; Garcia-Canovas, Francisco

2011-12-01

The kinetics of tyrosinase acting on o-aminophenols and aromatic amines as substrates was studied. The catalytic constants of aromatic monoamines and o-diamines were both low, these results are consistent with our previous mechanism in which the slow step is the transfer of a proton by a hydroxyl to the peroxide in oxy-tyrosinase (Fenoll et al., Biochem. J. 380 (2004) 643-650). In the case of o-aminophenols, the hydroxyl group indirectly cooperates in the transfer of the proton and consequently the catalytic constants in the action of tyrosinase on these compounds are higher. In the case of aromatic monoamines, the Michaelis constants are of the same order of magnitude than for monophenols, which suggests that the monophenols bind better (higher binding constant) to the enzyme to facilitate the π-π interactions between the aromatic ring and a possible histidine of the active site. In the case of aromatic o-diamines, both the catalytic and Michaelis constants are low, the values of the catalytic constants being lower than those of the corresponding o-diphenols. The values of the Michaelis constants of the aromatic o-diamines are slightly lower than those of their corresponding o-diphenols, confirming that the aromatic o-diamines bind less well (lower binding constant) to the enzyme. Copyright © 2011 Elsevier B.V. All rights reserved.

Time-dependent boundary conditions for hyperbolic systems. II

NASA Technical Reports Server (NTRS)

Thompson, Kevin W.

1990-01-01

A general boundary condition formalism is developed for all types of boundary conditions to which hyperbolic systems are subject; the formalism makes possible a 'cookbook' approach to boundary conditions, by means of which novel boundary 'recipes' may be derived and previously devised ones may be consulted as required. Numerous useful conditions are derived for such CFD problems as subsonic and supersonic inflows and outflows, nonreflecting boundaries, force-free boundaries, constant pressure boundaries, and constant mass flux. Attention is given to the computation and integration of time derivatives.

Time-dependent boundary conditions for hyperbolic systems. II

NASA Astrophysics Data System (ADS)

Thompson, Kevin W.

1990-08-01

A general boundary condition formalism is developed for all types of boundary conditions to which hyperbolic systems are subject; the formalism makes possible a 'cookbook' approach to boundary conditions, by means of which novel boundary 'recipes' may be derived and previously devised ones may be consulted as required. Numerous useful conditions are derived for such CFD problems as subsonic and supersonic inflows and outflows, nonreflecting boundaries, force-free boundaries, constant pressure boundaries, and constant mass flux. Attention is given to the computation and integration of time derivatives.

Methane steam reforming rates over Pt, Rh and Ni(111) accounting for H tunneling and for metal lattice vibrations

NASA Astrophysics Data System (ADS)

German, Ernst D.; Sheintuch, Moshe

2017-02-01

Microkinetic models of methane steam reforming (MSR) over bare platinum and rhodium (111) surfaces are analyzed in present work using calculated rate constants. The individual rate constants are classified into three different sets: (i) rate constants of adsorption and desorption steps of CH4, H2O, CO and of H2; (ii) rate constants of dissociation and formation of A-H bonds (A = C, O, and H), and (iii) rate constants of dissociation and formation of C-O bond. The rate constants of sets (i) and (iii) are calculated using transition state theory and published thermochemical data. The rate constants of H-dissociation reactions (set (ii)) are calculated in terms of a previously-developed approach that accounts for thermal metal lattice vibrations and for H tunneling through a potential barrier of height which depends on distance of AH from a surface. Pre-exponential factors of several group (ii) steps were calculated to be usually lower than the traditional kBT/h due to tunneling effect. Surface composition and overall MSR rates over platinum and rhodium surfaces are compared with those over nickel surface showing that operating conditions strongly affect on the activity order of the catalysts.

The ocean in near equilibrium with atmospheric methyl bromide

NASA Astrophysics Data System (ADS)

Hu, Lei; Yvon-Lewis, Shari; Liu, Yina; Bianchi, Thomas S.

2012-09-01

Saturation-anomaly measurements of methyl bromide (CH3Br) were made in the eastern Pacific (3/30-4/27, 2010) and the eastern Atlantic (10/25-11/26, 2010) to assess the oceanic saturation state as the phaseout of fumigation - non-Quarantine and Pre-Shipment (non-QPS) uses of CH3Br nears completion and atmospheric concentrations continue to decline. These cruises occurred 16 years after the Bromine Latitudinal Air-Sea Transect (BLAST) cruises, which were conducted in the same regions and first established a global oceanic net sink of -12.6 Gg yr-1 for atmospheric CH3Br in 1994. Results from this study suggest saturation anomalies of CH3Br in the surface ocean have become less negative than those observed 16 years ago as the atmospheric burden has declined over the past decade. The global net sea-to-air flux was estimated at 0 to 3 Gg yr-1 in 2010, suggesting that the ocean may become a net small source to atmospheric CH3Br. There are no significant differences between this study and previous studies for measured biological loss rate constants and calculated annual production rates, suggesting that annual production rates and biological degradation rate constants for CH3Br in the surface ocean have likely remained relatively constant over the past 16 years. When including the biological loss rate constants from this study and all previous studies, the mean global biological loss rate constant is constrained to 0.05 ± 0.01 d-1 (at a 95% confidence level). Combining chemical and eddy degradation rate constants, and using an updated gas transfer velocity, we estimate the CH3Br partial atmospheric lifetime with respect to oceanic loss to be 3.1 (2.3 to 5.0) years. Although the new partial atmospheric lifetime is about 1.3 years longer than the best prior estimate, it does not change the overall atmospheric lifetime of CH3Br, 0.8 (0.7-0.9) years.

A general circulation model study of the effects of faster rotation rate, enhanced CO2 concentration, and reduced solar forcing: Implications for the faint young sun paradox

NASA Technical Reports Server (NTRS)

Jenkins, Gregory S.

1993-01-01

Solar energy at the top of the atmosphere (solar constant), rotation rate, and carbon dioxide (CO2) may have varied significantly over Earth's history, especially during the earliest times. The sensitivity of a general circulation model to faster rotation, enhanced CO2 concentration, and reduced solar constant is presented. The control simulation of this study has a solar constant reduced by 10% the present amount, zero land fraction using a swamp ocean surface, CO2 concentrations of 330 ppmv, present-day rotation rate, and is integrated under mean diurnal and seasonal solar forcing. Four sensitivity test are performed under zero land fraction and reduced solar constant conditions by varying the earth's rotation rate atmospheric CO2 concentration and solar constant. The global mean sea surface temperatures (SSTs) compared to the control simulation: were 6.6 K to 12 K higher than the control's global mean temperature of 264.7 K. Sea ice is confined to higher latitudes in each experiment compared to the control, with ice-free areas equatorward of the subtropics. The warm SSTs are associated with a 20% reduction in clouds for the rotation rate experiments and higher CO2 concentrations in the other experiments. These results are in contrast to previous studies that have used energy balance and radiative convective models. Previous studies required a much larger atmospheric CO2 increase to prevent an ice-covered Earth. The results of the study, suggest that because of its possible feedback with clouds, the general circulation of the atmosphere should be taken into account in understanding the climate of early Earth. While higher CO2 concentrations are likely in view of the results, very large atmospheric CO2 concentrations may not be necessary to counterbalance the lower solar constant that existed early in Earth's history.

Evaluation of the kinetic oxidation of aqueous volatile organic compounds by permanganate.

PubMed

Mahmoodlu, Mojtaba G; Hassanizadeh, S Majid; Hartog, Niels

2014-07-01

The use of permanganate solutions for in-situ chemical oxidation (ISCO) is a well-established groundwater remediation technology, particularly for targeting chlorinated ethenes. The kinetics of oxidation reactions is an important ISCO remediation design aspect that affects the efficiency and oxidant persistence. The overall rate of the ISCO reaction between oxidant and contaminant is typically described using a second-order kinetic model while the second-order rate constant is determined experimentally by means of a pseudo first order approach. However, earlier studies of chlorinated hydrocarbons have yielded a wide range of values for the second-order rate constants. Also, there is limited insight in the kinetics of permanganate reactions with fuel-derived groundwater contaminants such as toluene and ethanol. In this study, batch experiments were carried out to investigate and compare the oxidation kinetics of aqueous trichloroethylene (TCE), ethanol, and toluene in an aqueous potassium permanganate solution. The overall second-order rate constants were determined directly by fitting a second-order model to the data, instead of typically using the pseudo-first-order approach. The second-order reaction rate constants (M(-1) s(-1)) for TCE, toluene, and ethanol were 8.0×10(-1), 2.5×10(-4), and 6.5×10(-4), respectively. Results showed that the inappropriate use of the pseudo-first-order approach in several previous studies produced biased estimates of the second-order rate constants. In our study, this error was expressed as a function of the extent (P/N) in which the reactant concentrations deviated from the stoichiometric ratio of each oxidation reaction. The error associated with the inappropriate use of the pseudo-first-order approach is negatively correlated with the P/N ratio and reached up to 25% of the estimated second-order rate constant in some previous studies of TCE oxidation. Based on our results, a similar relation is valid for the other volatile organic compounds studied. Copyright © 2013 Elsevier B.V. All rights reserved.

H{sub 2}—AgCl: A spectroscopic study of a dihydrogen complex

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

Grubbs, G. S.; Obenchain, Daniel A.; Pickett, Herbert M.

2014-09-21

H{sub 2}—AgCl has been observed on a Fourier transform microwave spectrometer equipped with laser ablation source and determined to be a dihydrogen complex. Transitions up to J = 3–2 have been measured and analyzed for four isotopologues of the complex containing ortho and para H{sub 2}. The ortho and para spin states have been included in one fit, a deviation from the typical H{sub 2} complex. Rotational constants B and C, centrifugal distortion constants Δ{sub J} and Δ{sub JK}, nuclear electric quadrupole coupling constants χ{sub aa}, χ{sub bb}, and χ{sub cc} for {sup 35}Cl and {sup 37}Cl have been fitmore » for both spin states while nuclear spin-nuclear spin constants D{sub aa}, D{sub bb}, and D{sub cc}, and nuclear spin-rotation constant C{sub aa} have been reported for the ortho spin state. Quantum chemical calculations predict a strong bonding interaction and the strength of the complex has been related to reported χ{sub aa} and Δ{sub J} values amongst a host of comparable species, including the AgCl monomer itself. Bond lengths have been determined for Ag—Cl, Ag—H{sub 2} center-of-mass, and H—H and are reported.« less

Scale covariant gravitation. V - Kinetic theory. VI - Stellar structure and evolution

NASA Technical Reports Server (NTRS)

Hsieh, S.-H.; Canuto, V. M.

1981-01-01

A scale covariant kinetic theory for particles and photons is developed. The mathematical framework of the theory is given by the tangent bundle of a Weyl manifold. The Liouville equation is derived, and solutions to corresponding equilibrium distributions are presented and shown to yield thermodynamic results identical to the ones obtained previously. The scale covariant theory is then used to derive results of interest to stellar structure and evolution. A radiative transfer equation is derived that can be used to study stellar evolution with a variable gravitational constant. In addition, it is shown that the sun's absolute luminosity scales as L approximately equal to GM/kappa, where kappa is the stellar opacity. Finally, a formula is derived for the age of globular clusters as a function of the gravitational constant using a previously derived expression for the absolute luminosity.

VO2 kinetics of constant-load exercise following bed-rest-induced deconditioning

NASA Technical Reports Server (NTRS)

Convertino, V. A.; Goldwater, D. J.; Sandler, H.

1984-01-01

Previous studies have shown that the oxygen uptake kinetics during exercise and recovery may be changed by alterations in work intensity, prior exercise, muscle group involvement, ambient conditions, posture, disease state, and level of physical conditioning. However, the effects of detraining on oxygen uptake kinetics have not been determined. The present investigation has the objective to determine the effects of deconditioning following seven days of continuous head-down bed rest on changes in steady-state oxygen uptake, O2 deficit, and recovery oxygen uptake during the performance of constant-load exercise. The obtained results may provide support for previous proposals that submaximal oxygen uptake was significantly reduced following bed rest. The major finding was that bed-rest deconditioning resulted in a reduction of total O2 transport/utilization capacity during the transient phase of upright but not supine exercise.

USSR Report, Physics and Mathematics

DTIC Science & Technology

1985-08-20

TEKHNICHESKIY FIZIKI, No 6(148), Nov-Dec 84) 80 Thermodynamic Potential of Quark -Antiquark Plasma in Constant Chromomagnetic Field CSh. S. Agayev... QUARK -ANTIQUARK PLASMA IN CONSTANT CHROMOMAGNETIC FIELD Tomsk IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY: FIZIKA in Russian Vol 28, No 1, Jan 85...Automation Institute; Moscow State University imeni M. V. Lomonosov [Abstract] Light-neutral quark -antiquark plasma in a constant optical magnetic

A full set of langatate high-temperature acoustic wave constants: elastic, piezoelectric, dielectric constants up to 900°C.

PubMed

Davulis, Peter M; da Cunha, Mauricio Pereira

2013-04-01

A full set of langatate (LGT) elastic, dielectric, and piezoelectric constants with their respective temperature coefficients up to 900°C is presented, and the relevance of the dielectric and piezoelectric constants and temperature coefficients are discussed with respect to predicted and measured high-temperature SAW propagation properties. The set of constants allows for high-temperature acoustic wave (AW) propagation studies and device design. The dielectric constants and polarization and conductive losses were extracted by impedance spectroscopy of parallel-plate capacitors. The measured dielectric constants at high temperatures were combined with previously measured LGT expansion coefficients and used to determine the elastic and piezoelectric constants using resonant ultrasound spectroscopy (RUS) measurements at temperatures up to 900°C. The extracted LGT piezoelectric constants and temperature coefficients show that e11 and e14 change by up to 62% and 77%, respectively, for the entire 25°C to 900°C range when compared with room-temperature values. The LGT high-temperature constants and temperature coefficients were verified by comparing measured and predicted phase velocities (vp) and temperature coefficients of delay (TCD) of SAW delay lines fabricated along 6 orientations in the LGT plane (90°, 23°, Ψ) up to 900°C. For the 6 tested orientations, the predicted SAW vp agree within 0.2% of the measured vp on average and the calculated TCD is within 9.6 ppm/°C of the measured value on average over the temperature range of 25°C to 900°C. By including the temperature dependence of both dielectric and piezoelectric constants, the average discrepancies between predicted and measured SAW properties were reduced, on average: 77% for vp, 13% for TCD, and 63% for the turn-over temperatures analyzed.

Direct dynamics simulations of the unimolecular dissociation of dioxetane: Probing the non-RRKM dynamics

NASA Astrophysics Data System (ADS)

Malpathak, Shreyas; Ma, Xinyou; Hase, William L.

2018-04-01

In a previous UB3LYP/6-31G* direct dynamics simulation, non-Rice-Ramsperger-Kassel-Marcus (RRKM) unimolecular dynamics was found for vibrationally excited 1,2-dioxetane (DO); [R. Sun et al., J. Chem. Phys. 137, 044305 (2012)]. In the work reported here, these dynamics are studied in more detail using the same direct dynamics method. Vibrational modes of DO were divided into 4 groups, based on their characteristic motions, and each group excited with the same energy. To compare with the dynamics of these groups, an additional group of trajectories comprising a microcanonical ensemble was also simulated. The results of these simulations are consistent with the previous study. The dissociation probability, N(t)/N(0), for these excitation groups were all different. Groups A, B, and C, without initial excitation in the O-O stretch reaction coordinate, had a time lag to of 0.25-1.0 ps for the first dissociation to occur. Somewhat surprisingly, the C-H stretch Group A and out-of-plane motion Group C excitations had exponential dissociation probabilities after to, with a rate constant ˜2 times smaller than the anharmonic RRKM value. Groups B and D, with excitation of the H-C-H bend and wag, and ring bend and stretch modes, respectively, had bi-exponential dissociation probabilities. For Group D, with excitation localized in the reaction coordinate, the initial rate constant is ˜7 times larger than the anharmonic RRKM value, substantial apparent non-RRKM dynamics. N(t)/N(0) for the random excitation trajectories was non-exponential, indicating intrinsic non-RRKM dynamics. For the trajectory integration time of 13.5 ps, 9% of these trajectories did not dissociate in comparison to the RRKM prediction of 0.3%. Classical power spectra for these trajectories indicate they have regular intramolecular dynamics. The N(t)/N(0) for the excitation groups are well described by a two-state coupled phase space model. From the intercept of N(t)/N(0) with random excitation, the anharmonic correction to the RRKM rate constant is approximately a factor of 1.5.

GLT-1 Transport Stoichiometry Is Constant at Low and High Glutamate Concentrations when Chloride Is Substituted by Gluconate

PubMed Central

Kabakov, Anatoli Y.; Rosenberg, Paul A.

2015-01-01

Glutamate is the major excitatory neurotransmitter, but prolonged exposure even at micromolar concentrations causes neuronal death. Extracellular glutamate is maintained at nanomolar level by glutamate transporters, which, however, may reverse transport and release glutamate. If and when the reverse occurs depends on glutamate transport stoichiometry (GTS). Previously we found that in the presence of chloride, the coupled GLT-1 glutamate transporter current and its relationship to radiolabeled glutamate flux significantly decreased when extracellular glutamate concentration increased above 0.2 mM, which implies a change in GTS. Such high concentrations are feasible near GLT-1 expressed close to synaptic release site during excitatory neurotransmission. The aim of this study was to determine GLT-1 GTS at both low (19–75 μM) and high (300–1200 μM) glutamate concentration ranges. GTS experiments were conducted in the absence of chloride to avoid contributions by the GLT-1 uncoupled chloride conductance. Mathematical analysis of the transporter thermodynamic equilibrium allowed us to derive equations revealing the number of a particular type of ion transported per elementary charge based on the measurements of the transporter reversal potential. We found that GLT-1a expressed in COS-7 cells co-transports 1.5 Na+, 0.5 Glu-, 0.5 H+ and counter-transports 0.6 K+ per elementary charge in both glutamate concentration ranges, and at both 37°C and 26°C temperatures. The thermodynamic parameter Q 10 = 2.4 for GLT-1 turnover rate of 19 s-1 (37°C, -50 mV) remained constant in the 10 μM–10 mM glutamate concentration range. Importantly, the previously reported decrease in the current/flux ratio at high glutamate concentration was not seen in the absence of chloride in both COS-7 cells and cultured rat neurons. Therefore, only in the absence of chloride, GLT-1 GTS remains constant at all glutamate concentrations. Possible explanations for why apparent GTS might vary in the presence of chloride are discussed. PMID:26301411

Pulse echo and combined resonance techniques: a full set of LGT acoustic wave constants and temperature coefficients.

PubMed

Sturtevant, Blake T; Davulis, Peter M; da Cunha, Mauricio Pereira

2009-04-01

This work reports on the determination of langatate elastic and piezoelectric constants and their associated temperature coefficients employing 2 independent methods, the pulse echo overlap (PEO) and a combined resonance technique (CRT) to measure bulk acoustic wave (BAW) phase velocities. Details on the measurement techniques are provided and discussed, including the analysis of the couplant material in the PEO technique used to couple signal to the sample, which showed to be an order of magnitude more relevant than the experimental errors involved in the data extraction. At room temperature, elastic and piezoelectric constants were extracted by the PEO and the CRT methods and showed results consistent to within a few percent for the elastic constants. Both raw acquired data and optimized constants, based on minimization routines applied to all the modes involved in the measurements, are provided and discussed. Comparison between the elastic constants and their temperature behavior with the literature reveals the recent efforts toward the consistent growth and characterization of LGT, in spite of significant variations (between 1 and 30%) among the constants extracted by different groups at room temperature. The density, dielectric permittivity constants, and respective temperature coefficients used in this work have also been independently determined based on samples from the same crystal boule. The temperature behavior of the BAW modes was extracted using the CRT technique, which has the advantage of not relying on temperature dependent acoustic couplants. Finally, the extracted temperature coefficients for the elastic and piezoelectric constants between room temperature and 120 degrees C are reported and discussed in this work.

Assimilation efficiency and toxicokinetics of 14C-lindane in the terrestrial isopod Porcellionides pruinosus: the role of isopods in degradation of persistent soil pollutants.

PubMed

Loureiro, Susana; Sousa, J P; Nogueira, A J A; Soares, A M V M

2002-12-01

An achievable way to evaluate the bioavailability of a certain toxic in the environment is to measure the concentration inside soil organisms. Non-target saprotrophic organisms like isopods are often exposed to agrochemicals or other kind of persistent chemicals. In this study the isopod Porcellionides pruinosus was exposed to a constant concentration of Lindane (gamma-HCH) via food. Using toxicokinetic models the bioaccumulation and fate of the pesticide by isopods was assessed and compared with previous studies, where an unexpected decrease in gamma-HCH concentration was observed. Animal body burdens showed higher values, and a lower assimilation rate constant, although the elimination rate constant was twice the value previously observed. It was also observed that a significant amount of gamma-HCH had an unknown fate. To discover its possible destiny, a factorial experiment was carried out using two types of CO2 traps and contaminated leaves in the presence and absence of isopods. It was concluded that isopod activity might have been responsible for a more rapid biotransformation of gamma-HCH in leaves, since the amount of the pesticide is reduced in their presence.

Calculation of crystalline lens power in chickens with a customized version of Bennett's equation.

PubMed

Iribarren, Rafael; Rozema, Jos J; Schaeffel, Frank; Morgan, Ian G

2014-03-01

This paper customizes Bennett's equation for calculating lens power in chicken eyes from refraction, keratometry and biometry. Previously published data on refraction, corneal power, anterior chamber depth, lens thickness, lens radii of curvature, axial length and eye power in chickens aged 10-90 days were used to estimate Gullstrand's lens power and Bennett's lens power for chicken eyes, and to calculate the lens equivalent refractive index. Bennett's A and B constants for the front and back surface powers of the lens were calculated for data measured from day 10 to 90 at 10 day intervals, and mean customized constants were calculated. The mean customized constants for Bennett's equation for chicks were A=0.574±0.023 and B=0.379±0.021. As found previously, lens power decreases with age in chicks, while corneal power decreases and axial length increases. The lens equivalent refractive index decreases with age from 10 to 90 days after hatching. Bennett's equation can be used to calculate lens power in chicken eyes for studies on animal myopia, using standard biometry. Copyright © 2014 Elsevier B.V. All rights reserved.

Linear perturbations in spherically symmetric dust cosmologies including a cosmological constant

NASA Astrophysics Data System (ADS)

Meyer, Sven; Bartelmann, Matthias

2017-12-01

We study the dynamical behaviour of gauge-invariant linear perturbations in spherically symmetric dust cosmologies including a cosmological constant. In contrast to spatially homogeneous FLRW models, the reduced degree of spatial symmetry causes a non-trivial dynamical coupling of gauge-invariant quantities already at first order perturbation theory and the strength and influence of this coupling on the spacetime evolution is investigated here. We present results on the underlying dynamical equations augmented by a cosmological constant and integrate them numerically. We also present a method to derive cosmologically relevant initial variables for this setup. Estimates of angular power spectra for each metric variable are computed and evaluated on the central observer's past null cone. By comparing the full evolution to the freely evolved initial profiles, the coupling strength will be determined for a best fit radially inhomogeneous patch obtained in previous works (see [1]). We find that coupling effects are not noticeable within the cosmic variance limit and can therefore safely be neglected for a relevant cosmological scenario. On the contrary, we find very strong coupling effects in a best fit spherical void model matching the distance redshift relation of SNe which is in accordance with previous findings using parametric void models.

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

Nersisyan, Henrik; Cid, Adrian Fernandez; Amendola, Luca, E-mail: h.nersisyan@thphys.uni-heidelberg.de, E-mail: fernandez@thphys.uni-heidelberg.de, E-mail: l.amendola@thphys.uni-heidelberg.de

In this work, we extend previous analyses of the structure formation in the f (□{sup −1} R ) model of nonlocal gravity proposed by Deser and Woodard (DW), which reproduces the background expansion of ΛCDM with no need of a cosmological constant nor of any dimensional constant beside Newton's one. A previous analysis based on redshift-space distortions (RSD) data concluded that the model was ruled out. In this work we revisit the issue and find that, when recast in a localized model, the DW model is not ruled out and actually gives a better fit to RSD data than ΛCDM.more » In fact, the DW model presents a suppressed growth of matter perturbations with respect to ΛCDM and a slightly lower value of σ{sub 8}, as favored by observations. We also produce analytical approximations of the two modified gravity functions, i.e. the anisotropic stress η and the relative change of Newton's constant Y , and of f σ{sub 8}( z ) as a function of redshift. Finally, we also show how much the fit depends on initial conditions when these are generalized with respect to a standard matter-dominated era.« less

MDN-0170, a New Napyradiomycin from Streptomyces sp. Strain CA-271078

PubMed Central

Lacret, Rodney; Pérez-Victoria, Ignacio; Oves-Costales, Daniel; de la Cruz, Mercedes; Domingo, Elizabeth; Martín, Jesús; Díaz, Caridad; Vicente, Francisca; Genilloud, Olga; Reyes, Fernando

2016-01-01

A new napyradiomycin, MDN-0170 (1), was isolated from the culture broth of the marine-derived actinomycete strain CA-271078, together with three known related compounds identified as 4-dehydro-4a-dechloronapyradiomycin A1 (2), napyradiomycin A1 (3) and 3-chloro-6,8-dihydroxy-8-α-lapachone (4). The structure of the new compound was determined using a combination of spectroscopic techniques, including 1D and 2D NMR and electrospray-time of flight mass spectrometry (ESI-TOF MS). The relative configuration of compound 1, which contains two independent stereoclusters, has been established by molecular modelling in combination with nOe and coupling constant analyses. Biosynthetic arguments also allowed us to propose its absolute stereochemistry. The antimicrobial properties of the compounds isolated were evaluated against methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Aspergillus fumigatus, and Candida albicans. The potent bioactivity previously reported for compounds 2 and 3 against methicillin-sensitive S. aureus has been extended to methicillin-resistant strains in this report. PMID:27763545

Marginalization in neural circuits with divisive normalization

PubMed Central

Beck, J.M.; Latham, P.E.; Pouget, A.

2011-01-01

A wide range of computations performed by the nervous system involves a type of probabilistic inference known as marginalization. This computation comes up in seemingly unrelated tasks, including causal reasoning, odor recognition, motor control, visual tracking, coordinate transformations, visual search, decision making, and object recognition, to name just a few. The question we address here is: how could neural circuits implement such marginalizations? We show that when spike trains exhibit a particular type of statistics – associated with constant Fano factors and gain-invariant tuning curves, as is often reported in vivo – some of the more common marginalizations can be achieved with networks that implement a quadratic nonlinearity and divisive normalization, the latter being a type of nonlinear lateral inhibition that has been widely reported in neural circuits. Previous studies have implicated divisive normalization in contrast gain control and attentional modulation. Our results raise the possibility that it is involved in yet another, highly critical, computation: near optimal marginalization in a remarkably wide range of tasks. PMID:22031877

Prevalence of Experiences With Consensual Nonmonogamous Relationships: Findings From Two National Samples of Single Americans.

PubMed

Haupert, M L; Gesselman, Amanda N; Moors, Amy C; Fisher, Helen E; Garcia, Justin R

2017-07-04

Although academic and popular interest in consensual nonmonogamy (CNM) is increasing, little is known about the prevalence of CNM. Using two separate U.S. Census based quota samples of single adults in the United States (Study 1: n = 3,905; Study 2: n = 4,813), the present studies show that more than one in five (21.9% in Study 1; 21.2% in Study 2) participants report engaging in CNM at some point in their lifetime. This proportion remained constant across age, education level, income, religion, region, political affiliation, and race, but varied with gender and sexual orientation. Specifically, men (compared to women) and people who identify as gay, lesbian, or bisexual (compared to those who identify as heterosexual) were more likely to report previous engagement in CNM. These findings suggest that a sizable and diverse proportion of U.S. adults have experienced CNM, highlighting the need to incorporate CNM into theoretical and empirical therapy and family science work.

Space Shuttle astrodynamical constants

NASA Technical Reports Server (NTRS)

Cockrell, B. F.; Williamson, B.

1978-01-01

Basic space shuttle astrodynamic constants are reported for use in mission planning and construction of ground and onboard software input loads. The data included here are provided to facilitate the use of consistent numerical values throughout the project.

An initial-abstraction, constant-loss model for unit hydrograph modeling for applicable watersheds in Texas

USGS Publications Warehouse

Asquith, William H.; Roussel, Meghan C.

2007-01-01

Estimation of representative hydrographs from design storms, which are known as design hydrographs, provides for cost-effective, riskmitigated design of drainage structures such as bridges, culverts, roadways, and other infrastructure. During 2001?07, the U.S. Geological Survey (USGS), in cooperation with the Texas Department of Transportation, investigated runoff hydrographs, design storms, unit hydrographs,and watershed-loss models to enhance design hydrograph estimation in Texas. Design hydrographs ideally should mimic the general volume, peak, and shape of observed runoff hydrographs. Design hydrographs commonly are estimated in part by unit hydrographs. A unit hydrograph is defined as the runoff hydrograph that results from a unit pulse of excess rainfall uniformly distributed over the watershed at a constant rate for a specific duration. A time-distributed, watershed-loss model is required for modeling by unit hydrographs. This report develops a specific time-distributed, watershed-loss model known as an initial-abstraction, constant-loss model. For this watershed-loss model, a watershed is conceptualized to have the capacity to store or abstract an absolute depth of rainfall at and near the beginning of a storm. Depths of total rainfall less than this initial abstraction do not produce runoff. The watershed also is conceptualized to have the capacity to remove rainfall at a constant rate (loss) after the initial abstraction is satisfied. Additional rainfall inputs after the initial abstraction is satisfied contribute to runoff if the rainfall rate (intensity) is larger than the constant loss. The initial abstraction, constant-loss model thus is a two-parameter model. The initial-abstraction, constant-loss model is investigated through detailed computational and statistical analysis of observed rainfall and runoff data for 92 USGS streamflow-gaging stations (watersheds) in Texas with contributing drainage areas from 0.26 to 166 square miles. The analysis is limited to a previously described, watershed-specific, gamma distribution model of the unit hydrograph. In particular, the initial-abstraction, constant-loss model is tuned to the gamma distribution model of the unit hydrograph. A complex computational analysis of observed rainfall and runoff for the 92 watersheds was done to determine, by storm, optimal values of initial abstraction and constant loss. Optimal parameter values for a given storm were defined as those values that produced a modeled runoff hydrograph with volume equal to the observed runoff hydrograph and also minimized the residual sum of squares of the two hydrographs. Subsequently, the means of the optimal parameters were computed on a watershed-specific basis. These means for each watershed are considered the most representative, are tabulated, and are used in further statistical analyses. Statistical analyses of watershed-specific, initial abstraction and constant loss include documentation of the distribution of each parameter using the generalized lambda distribution. The analyses show that watershed development has substantial influence on initial abstraction and limited influence on constant loss. The means and medians of the 92 watershed-specific parameters are tabulated with respect to watershed development; although they have considerable uncertainty, these parameters can be used for parameter prediction for ungaged watersheds. The statistical analyses of watershed-specific, initial abstraction and constant loss also include development of predictive procedures for estimation of each parameter for ungaged watersheds. Both regression equations and regression trees for estimation of initial abstraction and constant loss are provided. The watershed characteristics included in the regression analyses are (1) main-channel length, (2) a binary factor representing watershed development, (3) a binary factor representing watersheds with an abundance of rocky and thin-soiled terrain, and (4) curve numb

Absolute rate constant for the reaction of atomic chlorine with hydrogen peroxide vapor over the temperature range 265-400 K

NASA Technical Reports Server (NTRS)

Michael, J. V.; Whytock, D. A.; Lee, J. H.; Payne, W. A.; Stief, L. J.

1977-01-01

Rate constants for the reaction of atomic chlorine with hydrogen peroxide were measured from 265-400 K using the flash photolysis-resonance fluorescence technique. Analytical techniques were developed to measure H2O2 under reaction conditions. Due to ambiguity in the interpretation of the analytical results, the data combine to give two equally acceptable representations of the temperature dependence. The results are compared to previous work at 298 K and are theoretically discussed in terms of the mechanism of the reaction. Additional experiments on the H + H2O2 reaction at 298 and 359 K are compared with earlier results from this laboratory and give a slightly revised bimolecular rate constant.

Terminal attack trajectories of peregrine falcons are described by the proportional navigation guidance law of missiles

PubMed Central

Brighton, Caroline H.; Thomas, Adrian L. R.

2017-01-01

The ability to intercept uncooperative targets is key to many diverse flight behaviors, from courtship to predation. Previous research has looked for simple geometric rules describing the attack trajectories of animals, but the underlying feedback laws have remained obscure. Here, we use GPS loggers and onboard video cameras to study peregrine falcons, Falco peregrinus, attacking stationary targets, maneuvering targets, and live prey. We show that the terminal attack trajectories of peregrines are not described by any simple geometric rule as previously claimed, and instead use system identification techniques to fit a phenomenological model of the dynamical system generating the observed trajectories. We find that these trajectories are best—and exceedingly well—modeled by the proportional navigation (PN) guidance law used by most guided missiles. Under this guidance law, turning is commanded at a rate proportional to the angular rate of the line-of-sight between the attacker and its target, with a constant of proportionality (i.e., feedback gain) called the navigation constant (N). Whereas most guided missiles use navigation constants falling on the interval 3 ≤ N ≤ 5, peregrine attack trajectories are best fitted by lower navigation constants (median N < 3). This lower feedback gain is appropriate at the lower flight speed of a biological system, given its presumably higher error and longer delay. This same guidance law could find use in small visually guided drones designed to remove other drones from protected airspace. PMID:29203660

Terminal attack trajectories of peregrine falcons are described by the proportional navigation guidance law of missiles.

PubMed

Brighton, Caroline H; Thomas, Adrian L R; Taylor, Graham K

2017-12-19

The ability to intercept uncooperative targets is key to many diverse flight behaviors, from courtship to predation. Previous research has looked for simple geometric rules describing the attack trajectories of animals, but the underlying feedback laws have remained obscure. Here, we use GPS loggers and onboard video cameras to study peregrine falcons, Falco peregrinus , attacking stationary targets, maneuvering targets, and live prey. We show that the terminal attack trajectories of peregrines are not described by any simple geometric rule as previously claimed, and instead use system identification techniques to fit a phenomenological model of the dynamical system generating the observed trajectories. We find that these trajectories are best-and exceedingly well-modeled by the proportional navigation (PN) guidance law used by most guided missiles. Under this guidance law, turning is commanded at a rate proportional to the angular rate of the line-of-sight between the attacker and its target, with a constant of proportionality (i.e., feedback gain) called the navigation constant ( N ). Whereas most guided missiles use navigation constants falling on the interval 3 ≤ N ≤ 5, peregrine attack trajectories are best fitted by lower navigation constants (median N < 3). This lower feedback gain is appropriate at the lower flight speed of a biological system, given its presumably higher error and longer delay. This same guidance law could find use in small visually guided drones designed to remove other drones from protected airspace. Copyright © 2017 the Author(s). Published by PNAS.

Lattice-dynamical model for the filled skutterudite LaFe4Sb12: Harmonic and anharmonic couplings

NASA Astrophysics Data System (ADS)

Feldman, J. L.; Singh, D. J.; Bernstein, N.

2014-06-01

The filled skutterudite LaFe4Sb12 shows greatly reduced thermal conductivity compared to that of the related unfilled compound CoSb3, although the microscopic reasons for this are unclear. We calculate harmonic and anharmonic force constants for the interaction of the La filler atom with the framework atoms. We find that force constants show a general trend of decaying rapidly with distance and are very small for the interaction of the La with its next-nearest-neighbor Sb and nearest-neighbor La. However, a few rather long-range interactions, such as with the next-nearest-neighbor La and with the third neighbor Sb, are surprisingly strong, although still small. We test the central-force approximation and find significant deviations from it. Using our force constants we calculate a bare La mode Gruneisen parameter and find a value of 3-4, substantially higher than values associated with cage atom anharmonicity, i.e., a value of about 1 for CoSb3 but much smaller than a previous estimate [Bernstein et al., Phys. Rev. B 81, 134301 (2010), 10.1103/PhysRevB.81.134301]. This latter difference is primarily due to the previously used overestimate of the La-Fe cubic force constants. We also find a substantial negative contribution to this bare La Gruneisen parameter from the aforementioned third-neighbor La-Sb interaction. Our results underscore the need for rather long-range interactions in describing the role of anharmonicity on the dynamics in this material.

Test and evaluation of constant-flow devices for use in SSN AFFF proportioning systems. Interim report, January-May 1986

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

Williams, F.W.; Back, G.G.; Burns, R.E.

1986-11-04

Constant flow devices, which deliver a constant flow of liquid over a range of upstream and downstream pressures, have been suggested as an alternative to orifice plates for proportioning AFFF in SSN 21 fire-suppression systems. Operational and performance characteristics of two lightweight, inexpensive, commercially available constant-flow devices have significant advantages over orifice plates. Both models tested, however, showed performance degradation when subjected to simulated service conditions. A constant flow device with improved resistance to wear and to AFFF exposure is desirable. Since the constant-flow control devices tested improves proportioning efficiency but do not have optimum characteristics, investigation of improved devicesmore » or methods is recommended.« less

A rigorous full-dimensional quantum dynamics study of tunneling splitting of rovibrational states of vinyl radical C 2 H 3

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

Yu, Hua-Gen; Song, Hongwei; Yang, Minghui

Here, we report a rigorous quantum mechanical study of the rovibrational energy levels of vinyl radical C 2H 3. The calculations are carried out using a real two-component multi-layer Lanczos algorithm in a set of orthogonal polyspherical coordinates based on a recently developed accurate ab initio potential energy surface of C 2H 3. All well converged 158 vibrational bands up to 3200 cm -1 are determined, together with a comparison to previous calculations and experimental results. Our results show a remarkable multi-dimensional tunneling effect on the vibrational spectra of the radical. The vibrational tunneling splitting is substantially different from thatmore » of previous reduced dimensional calculations. The rotational constants of the fundamental vibrational bands of C 2H 3 are also given. It was found that the rovibrational states are strongly coupled, especially among those bending vibrational modes. Additionally, the perturbative iteration approach of Gruebele has been extended to assign the rovibrational energy levels of C 2H 3 without the requirement of explicit wavefunctions.« less

A rigorous full-dimensional quantum dynamics study of tunneling splitting of rovibrational states of vinyl radical C2H3.

PubMed

Yu, Hua-Gen; Song, Hongwei; Yang, Minghui

2017-06-14

We report a rigorous quantum mechanical study of the rovibrational energy levels of vinyl radical C 2 H 3 . The calculations are carried out using a real two-component multi-layer Lanczos algorithm in a set of orthogonal polyspherical coordinates based on a recently developed accurate ab initio potential energy surface of C 2 H 3 . All well converged 158 vibrational bands up to 3200 cm -1 are determined, together with a comparison to previous calculations and experimental results. Results show a remarkable multi-dimensional tunneling effect on the vibrational spectra of the radical. The vibrational tunneling splitting is substantially different from that of previous reduced dimensional calculations. The rotational constants of the fundamental vibrational bands of C 2 H 3 are also given. It was found that the rovibrational states are strongly coupled, especially among those bending vibrational modes. In addition, the perturbative iteration approach of Gruebele has been extended to assign the rovibrational energy levels of C 2 H 3 without the requirement of explicit wavefunctions.

A rigorous full-dimensional quantum dynamics study of tunneling splitting of rovibrational states of vinyl radical C 2 H 3

DOE PAGES

Yu, Hua-Gen; Song, Hongwei; Yang, Minghui

2017-06-12

Here, we report a rigorous quantum mechanical study of the rovibrational energy levels of vinyl radical C 2H 3. The calculations are carried out using a real two-component multi-layer Lanczos algorithm in a set of orthogonal polyspherical coordinates based on a recently developed accurate ab initio potential energy surface of C 2H 3. All well converged 158 vibrational bands up to 3200 cm -1 are determined, together with a comparison to previous calculations and experimental results. Our results show a remarkable multi-dimensional tunneling effect on the vibrational spectra of the radical. The vibrational tunneling splitting is substantially different from thatmore » of previous reduced dimensional calculations. The rotational constants of the fundamental vibrational bands of C 2H 3 are also given. It was found that the rovibrational states are strongly coupled, especially among those bending vibrational modes. Additionally, the perturbative iteration approach of Gruebele has been extended to assign the rovibrational energy levels of C 2H 3 without the requirement of explicit wavefunctions.« less

Kinetic and molecular orbital analyses of dicarboxylic acylcarnitine methylesterification show that derivatization may affect the screening of newborns by tandem mass spectrometry.

PubMed

Maeda, Yasuhiro; Nakajima, Yoko; Gotoh, Kana; Hotta, Yuji; Kataoka, Tomoya; Sugiyama, Naruji; Shirai, Naohiro; Ito, Tetsuya; Kimura, Kazunori

2016-01-01

Newborns are routinely screened for organic acidemias by acylcarnitine analysis. We previously reported the partial catalytic methylesterification of dicarboxylic acylcarnitines by benzenesulfonic acid moiety in the solid extraction cartridge during extraction from serum. Since the diagnosis of organic acidemias by tandem mass spectrometry is affected by the higher molecular weight of these derivatized acylcarnitines, we investigated the methylesterification conditions. The kinetic constants for the methylesterification of carboxyl groups on the acyl and carnitine sides of carnitine were 2.5 and 0.24h(-1), respectively. The physical basis underlying this difference in methylesterification rates was clarified theoretically, illustrating that methylesterification during extraction proceeds easily and must be prevented. Copyright © 2015 Elsevier Ltd. All rights reserved.

Corrosion, stress corrosion cracking, and electrochemistry of the iron and nickel base alloys in caustic environments. Progress report, 1 March 1977--28 February 1978

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

Staehle, R.W.; Agrawal, A.K.

1978-01-01

The straining electrode technique was used to evaluate the stress corrosion cracking (SCC) susceptibility of AISI 304 stainless steel in 20N NaOH solution, and of Inconel 600 Alloy and Incoloy 800 Alloy in boiling 17.5N NaOH solution. The crack propagation rate estimated from the straining experiments correlated well with the previous constant load experiments. It was found that the straining electrode technique is a useful method for estimating, through short term experiments, parameters like crack propagation rate, crack morphology, and repassivation rate, as a function of the electrode potential. The role of alloying elements on the crack propagation rate inmore » the above alloys are also discussed.« less

Solidification processing of monotectic alloy matrix composites

NASA Technical Reports Server (NTRS)

Frier, Nancy L.; Shiohara, Yuh; Russell, Kenneth C.

1989-01-01

Directionally solidified aluminum-indium alloys of the monotectic composition were found to form an in situ rod composite which obeys a lambda exp 2 R = constant relation. The experimental data shows good agreement with previously reported results. A theoretical boundary between cellular and dendritic growth conditions was derived and compared with experiments. The unique wetting characteristics of the monotectic alloys can be utilized to tailor the interface structure in metal matrix composites. Metal matrix composites with monotectic and hypermonotectic Al-In matrices were made by pressure infiltration, remelted and directionally solidified to observe the wetting characteristics of the alloys as well as the effect on structure of solidification in the constrained field of the fiber interstices. Models for monotectic growth are modified to take into account solidification in these constrained fields.

Investigations of homologous disaccharides by elastic incoherent neutron scattering and wavelet multiresolution analysis

NASA Astrophysics Data System (ADS)

Magazù, S.; Migliardo, F.; Vertessy, B. G.; Caccamo, M. T.

2013-10-01

In the present paper the results of a wavevector and thermal analysis of Elastic Incoherent Neutron Scattering (EINS) data collected on water mixtures of three homologous disaccharides through a wavelet approach are reported. The wavelet analysis allows to compare both the spatial properties of the three systems in the wavevector range of Q = 0.27 Å-1 ÷ 4.27 Å-1. It emerges that, differently from previous analyses, for trehalose the scalograms are constantly lower and sharper in respect to maltose and sucrose, giving rise to a global spectral density along the wavevector range markedly less extended. As far as the thermal analysis is concerned, the global scattered intensity profiles suggest a higher thermal restrain of trehalose in respect to the other two homologous disaccharides.

A note on the cracked plates reinforced by a line stiffener

NASA Technical Reports Server (NTRS)

Yahsi, O. S.; Erdogan, F.

1983-01-01

The problem of a cracked plate reinforced by a line stiffener is reconsidered. The original solution of this problem was given in the literature. Also, a variation of the problem with debonding between the plate and the stiffener near the cracked region was reported in the literature. However, the special case of the problem in which the crack tip terminates at the stiffener does not appear to have been studied. In practice, the solution may be necessary in order to assess the crack arrest effectiveness of the stiffener. The problem of a stiffened plate with a crack is reformulated, the asymptotic stress state near the crack tip terminating at the stiffener is examined, and numerical results are given for various stiffness constants. Previously announced in STAR as N83-21388

Low-voltage organic transistors on plastic comprising high-dielectric constant gate insulators

PubMed

Dimitrakopoulos; Purushothaman; Kymissis; Callegari; Shaw

1999-02-05

The gate bias dependence of the field-effect mobility in pentacene-based insulated gate field-effect transistors (IGFETs) was interpreted on the basis of the interaction of charge carriers with localized trap levels in the band gap. This understanding was used to design and fabricate IGFETs with mobility of more than 0.3 square centimeter per volt per second and current modulation of 10(5), with the use of amorphous metal oxide gate insulators. These values were obtained at operating voltage ranges as low as 5 volts, which are much smaller than previously reported results. An all-room-temperature fabrication process sequence was used, which enabled the demonstration of high-performance organic IGFETs on transparent plastic substrates, at low operating voltages for organic devices.

Ab-initio calculations of the Ruddlesden Popper phases CaMnO3, CaO(CaMnO3) and CaO(CaMnO3)2

NASA Astrophysics Data System (ADS)

Cardoso, C.; Borges, R. P.; Gasche, T.; Godinho, M.

2008-01-01

The present work reports ab-initio density functional theory calculations for the Ruddlesden-Popper phase CaO(CaMnO3)n compounds. In order to study the evolution of the properties with the number of perovskite layers, a detailed analysis of the densities of states calculated for each compound and for several magnetic configurations was performed. The effect of distortions of the crystal structure on the magnetic ground state is also analysed and the exchange constants and transition temperatures are calculated for the three compounds using a mean field model. The calculated magnetic ground state structures and magnetic moments are in good agreement with experimental results and previous calculations.

Flattening and manipulation of the electronic structure of h-BN/Rh(111) nanomesh upon Sn intercalation

NASA Astrophysics Data System (ADS)

Sugiyama, Yuya; Bernard, Carlo; Okuyama, Yuma; Ideta, Shin-ichiro; Tanaka, Kiyohisa; Greber, Thomas; Hirahara, Toru

2018-06-01

We have deposited Sn on corrugated hexagonal boron nitride (h-BN) nanomeshs formed on Rh(111) and found that Sn atoms are intercalated between h-BN and Rh, flattening the h-BN. Our reflection high-energy electron diffraction (RHEED) analysis showed that the average in-plane lattice constant of h-BN increases due to the loss of the corrugation. Furthermore, electronic structure measurements based on angle-resolved photoemission spectroscopy (ARPES) showed that the h-BN π band width increases significantly while the σ band width does not change as much. These behaviors were partly different from previous reports on the intercalation of h-BN/Rh system. Our results offer a novel, simple method to control the electronic structure of h-BN.

Local conformational dynamics in alpha-helices measured by fast triplet transfer.

PubMed

Fierz, Beat; Reiner, Andreas; Kiefhaber, Thomas

2009-01-27

Coupling fast triplet-triplet energy transfer (TTET) between xanthone and naphthylalanine to the helix-coil equilibrium in alanine-based peptides allowed the observation of local equilibrium fluctuations in alpha-helices on the nanoseconds to microseconds time scale. The experiments revealed faster helix unfolding in the terminal regions compared with the central parts of the helix with time constants varying from 250 ns to 1.4 micros at 5 degrees C. Local helix formation occurs with a time constant of approximately 400 ns, independent of the position in the helix. Comparing the experimental data with simulations using a kinetic Ising model showed that the experimentally observed dynamics can be explained by a 1-dimensional boundary diffusion with position-independent elementary time constants of approximately 50 ns for the addition and of approximately 65 ns for the removal of an alpha-helical segment. The elementary time constant for helix growth agrees well with previously measured time constants for formation of short loops in unfolded polypeptide chains, suggesting that helix elongation is mainly limited by a conformational search.

A summary of the Planck constant determinations using the NRC Kibble balance

NASA Astrophysics Data System (ADS)

Wood, B. M.; Sanchez, C. A.; Green, R. G.; Liard, J. O.

2017-06-01

We present a summary of the Planck constant determinations using the NRC watt balance, now referred to as the NRC Kibble balance. The summary includes a reanalysis of the four determinations performed in late 2013, as well as three new determinations performed in 2016. We also present a number of improvements and modifications to the experiment resulting in lower noise and an improved uncertainty analysis. As well, we present a systematic error that had been previously unrecognized and we have quantified its correction. The seven determinations, using three different nominal masses and two different materials, are reanalysed in a manner consistent with that used by the CODATA Task Group on Fundamental Constants (TGFC) and includes a comprehensive assessment of correlations. The result is a Planck constant of 6.626 070 133(60)  ×10-34 Js and an inferred value of the Avogadro constant of 6.022 140 772(55)  ×1023 mol-1. These fractional uncertainties of less than 10-8 are the smallest published to date.

A ROIC for Mn(TPP)Cl-DOP-THF-Polyhema PVC membrane modified n-channel Si3N4 ISFET sensitive to histamine.

PubMed

Samah, N L M A; Lee, Khuan Y; Sulaiman, S A; Jarmin, R

2017-07-01

Intolerance of histamine could lead to scombroid poisoning with fatal consequences. Current detection methods for histamine are wet laboratory techniques which employ expensive equipment that depends on skills of seasoned technicians and produces delayed test analysis result. Previous works from our group has established that ISFETs can be adapted for detecting histamine with the use of a novel membrane. However, work to integrate ISFETs with a readout interfacing circuit (ROIC) circuit to display the histamine concentration has not been reported so far. This paper concerns the development of a ROIC specifically to integrate with a Mn(TPP)Cl-DOP-THF-Polyhema PVC membrane modified n-channel Si3N4 ISFET to display the histamine concentration. It embodies the design of constant voltage constant current (CVCC) circuit, amplification circuit and micro-controller based display circuit. A DC millivolt source is used to substitute the membrane modified ISFET as preliminary work. Input is histamine concentration corresponding to the safety level designated by the Food and Drugs Administration (FDA). Results show the CVCC circuit makes the output follows the input and keeps VDS constant. The amplification circuit amplifies the output from the CVCC circuit to the range 2.406-4.888V to integrate with the microcontroller, which is programmed to classify and display the histamine safety level and its corresponding voltage on a LCD panel. The ROIC could be used to produce direct output voltages corresponding to histamine concentrations, for in-situ applications.

Modeling the reactivities of hydroxyl radical and ozone towards atmospheric organic chemicals using quantitative structure-reactivity relationship approaches.

PubMed

Gupta, Shikha; Basant, Nikita; Mohan, Dinesh; Singh, Kunwar P

2016-07-01

The persistence and the removal of organic chemicals from the atmosphere are largely determined by their reactions with the OH radical and O3. Experimental determinations of the kinetic rate constants of OH and O3 with a large number of chemicals are tedious and resource intensive and development of computational approaches has widely been advocated. Recently, ensemble machine learning (EML) methods have emerged as unbiased tools to establish relationship between independent and dependent variables having a nonlinear dependence. In this study, EML-based, temperature-dependent quantitative structure-reactivity relationship (QSRR) models have been developed for predicting the kinetic rate constants for OH (kOH) and O3 (kO3) reactions with diverse chemicals. Structural diversity of chemicals was evaluated using a Tanimoto similarity index. The generalization and prediction abilities of the constructed models were established through rigorous internal and external validation performed employing statistical checks. In test data, the EML QSRR models yielded correlation (R (2)) of ≥0.91 between the measured and the predicted reactivities. The applicability domains of the constructed models were determined using methods based on descriptors range, Euclidean distance, leverage, and standardization approaches. The prediction accuracies for the higher reactivity compounds were relatively better than those of the low reactivity compounds. Proposed EML QSRR models performed well and outperformed the previous reports. The proposed QSRR models can make predictions of rate constants at different temperatures. The proposed models can be useful tools in predicting the reactivities of chemicals towards OH radical and O3 in the atmosphere.

Recent advances in thermal desorption-gas chromatography-mass spectrometery method to eliminate the matrix effect between air and water samples: application to the accurate determination of Henry's law constant.

PubMed

Kim, Yong-Hyun; Kim, Ki-Hyun

2014-05-16

Accurate values for the Henry's law constants are essential to describe the environmental dynamics of a solute, but substantial errors are recognized in many reported data due to practical difficulties in measuring solubility and/or vapor pressure. Despite such awareness, validation of experimental approaches has scarcely been made. An experimental approach based on thermal desorption-gas chromatography-mass spectrometery (TD-GC-MS) method was developed to concurrently allow the accurate determination of target compounds from the headspace and aqueous samples in closed equilibrated system. The analysis of six aromatics and eight non-aromatic oxygenates was then carried out in a static headspace mode. An estimation of the potential bias and mass balance (i.e., sum of mass measured individually from gas and liquid phases vs. the mass initially added to the system) demonstrates compound-specific phase dependency so that the best results are obtained by aqueous (less soluble aromatics) and headspace analysis (more soluble non-aromatics). Accordingly, we were able to point to the possible sources of biases in previous studies and provide the best estimates for the Henry's constants (Matm(-1)): benzene (0.17), toluene (0.15), p-xylene (0.13), m-xylene (0.13), o-xylene (0.19), styrene (0.27); propionaldehyde (9.26), butyraldehyde (6.19), isovaleraldehyde (2.14), n-valeraldehyde (3.98), methyl ethyl ketone (10.5), methyl isobutyl ketone (3.93), n-butyl acetate (2.41), and isobutyl alcohol (22.2). Copyright © 2014 Elsevier B.V. All rights reserved.

Kinetics of NH3 -oxidation, NO-turnover, N2 O-production and electron flow during oxygen depletion in model bacterial and archaeal ammonia oxidisers.

PubMed

Hink, Linda; Lycus, Pawel; Gubry-Rangin, Cécile; Frostegård, Åsa; Nicol, Graeme W; Prosser, James I; Bakken, Lars R

2017-12-01

Ammonia oxidising bacteria (AOB) are thought to emit more nitrous oxide (N 2 O) than ammonia oxidising archaea (AOA), due to their higher N 2 O yield under oxic conditions and denitrification in response to oxygen (O 2 ) limitation. We determined the kinetics of growth and turnover of nitric oxide (NO) and N 2 O at low cell densities of Nitrosomonas europaea (AOB) and Nitrosopumilus maritimus (AOA) during gradual depletion of TAN (NH 3  + NH4+) and O 2 . Half-saturation constants for O 2 and TAN were similar to those determined by others, except for the half-saturation constant for ammonium in N. maritimus (0.2 mM), which is orders of magnitudes higher than previously reported. For both strains, cell-specific rates of NO turnover and N 2 O production reached maxima near O 2 half-saturation constant concentration (2-10 μM O 2 ) and decreased to zero in response to complete O 2 -depletion. Modelling of the electron flow in N. europaea demonstrated low electron flow to denitrification (≤1.2% of the total electron flow), even at sub-micromolar O 2 concentrations. The results corroborate current understanding of the role of NO in the metabolism of AOA and suggest that denitrification is inconsequential for the energy metabolism of AOB, but possibly important as a route for dissipation of electrons at high ammonium concentration. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Charmed and light pseudoscalar meson decay constants from four-flavor lattice QCD with physical light quarks

DOE PAGES

Bazavov, A.; Bernard, C.; Komijani, J.; ...

2014-10-30

We compute the leptonic decay constants f D+, f Ds , and f K+, and the quark-mass ratios m c=m s and m s=m l in unquenched lattice QCD using the experimentally determined value of f π+ for normalization. We use the MILC Highly Improved Staggered Quark (HISQ) ensembles with four dynamical quark flavors -- up, down, strange, and charm -- and with both physical and unphysical values of the light sea-quark masses. The use of physical pions removes the need for a chiral extrapolation, thereby eliminating a significant source of uncertainty in previous calculations. Four different lattice spacing ranging from a ≈ 0:06 fm to 0:15 fm are included in the analysis to control the extrapolation to the continuum limit. Our primary results are f D+ = 212:6(0:4)more » $$(^{+1.0}_{-1.2})$$ MeV, f Ds = 249:0(0:3)$$(^{+1.1}_{-1.5})$$ MeV, and f Ds/f D+ = 1:1712(10)$$(^{+29}_{-32})$$, where the errors are statistical and total systematic, respectively. The errors on our results for the charm decay constants and their ratio are approximately two to four times smaller than those of the most precise previous lattice calculations. We also obtain f K+/ f π+ = 1:1956(10)$$(^{+26}_{-18})$$, updating our previous result, and determine the quark-mass ratios m s/m l = 27:35(5)$$(^{+10}_{-7})$$ and m c/m s = 11:747(19)$$(^{+59}_{-43})$$. When combined with experimental measurements of the decay rates, our results lead to precise determinations of the CKM matrix elements !Vus! = 0:22487(51)(29)(20)(5), !Vcd! = 0:217(1)(5)(1) and !Vcs! = 1:010(5)(18)(6), where the errors are from this calculation of the decay constants, the uncertainty in the experimental decay rates, structure-dependent electromagnetic corrections, and, in the case of !Vus!, the uncertainty in |Vud|, respectively.« less

Design and Growth of Novel Compounds for Radiation Sensors: Multinary Chalcogenides

NASA Technical Reports Server (NTRS)

Singh, N. B.; Su, Ching-Hua; Nagaradona, Teja; Arnold, Brad; Choa, Fow-Sen

2016-01-01

Increasing threats of radiological weapons have revitalized the researches for low cost large volume ?-ray and neutron ray sensors In the past few years we have designed and grown ternary and quaternary lead and thallium chalcogenides and lead selenoiodides for detectors to meet these challenges. These materials are congruent, can be tailored to enhance the parameters required for radiation sensors. In addition, this class of compounds can be grown by Bridgman method which promises for large volume productions. We have single crystals of several compounds from the melt including Tl3AsSe3, Tl3AsSe3-xSx, TlGaSe2, AgGaGe3Se8, AgxLi1-xAgGaGe3Se8 and PbTlI5-x Sex compounds. Experimental studies indicate that these have very low absorption coefficient, low defect density and can be fabricated in any shape and sizes. These crystals do not require post growth annealing and do not show any second phase precipitates when processed for electrode bonding and other fabrication steps. In this paper we report purification, growth and fabrication of large Tl3AsSe3 (TAS) crystals. We observed that TAS crystals grown by using further purification of as supplied high purity source materials followed by directionally solidified charge showed higher resistivity than previously reported values. TAS also showed constant value as the function of voltage. A low thermal gradient and high purity source material were used to reduce thermal stresses in large crystals. By improving the purification of the as supplied source materials very high quality thallium, selenium and arsenic was achieved for preparing stoichiometric Tl3AsSe3 compound. Low gradient (<20K/cm) and slow growth rate (1-2 cm/day) produced crystals with reduced stress. Crystals did not show any micro cracking during fabrication of crystals grown with high purity and at low thermal gradient. Since thallium is a major component and very sensitive to surface oxidation, removal of surface and bulk oxides is very important. Intentional increase in the growth rate from 1cm/day to higher speed (>5cm/day) showed very different morphologies on the surface of the crystals. Electrical resistivity was one order of magnitude higher than previously reported value and it was observed to be constant as the function of frequency.

Measurements of the optical properties of thin films of silver and silver oxide

NASA Technical Reports Server (NTRS)

Peters, Palmer N.; Sisk, Robert C.; Brown, Yolanda; Gregory, John C.; Nag, Pallob K.; Christl, Ligia

1995-01-01

The optical properties of silver films and their oxides are measured to better characterize such films for use as sensors for atomic oxygen. Good agreement between properties of measured pure silver films and reported optical constants is observed. Similar comparisons for silver oxide have not been possible because of a lack of reported constants, but self-consistencies and discrepancies in our measured results are described.

Compendium of Experimental Cetane Numbers

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

Yanowitz, Janet; Ratcliff, Matthew A.; McCormick, Robert L.

This report is an updated version of the 2014 Compendium of Experimental Cetane Number Data and presents a compilation of measured cetane numbers for pure chemical compounds. It includes all available single-compound cetane number data found in the scientific literature up until December 2016 as well as a number of previously unpublished values, most measured over the past decade at the National Renewable Energy Laboratory. This version of the compendium contains cetane values for 496 pure compounds, including 204 hydrocarbons and 292 oxygenates. 176 individual measurements are new to this version of the compendium, all of them collected using ASTMmore » Method D6890, which utilizes an Ignition Quality Tester (IQT) a type of constant-volume combustion chamber. For many compounds, numerous measurements are included, often collected by different researchers using different methods. The text of this document is unchanged from the 2014 version, except for the numbers of compounds in Section 3.1, the Appendices, Table 1. Primary Cetane Number Data Sources and Table 2. Number of Measurements Included in Compendium. Cetane number is a relative ranking of a fuel's autoignition characteristics for use in compression ignition engines. It is based on the amount of time between fuel injection and ignition, also known as ignition delay. The cetane number is typically measured either in a single-cylinder engine or a constant-volume combustion chamber. Values in the previous compendium derived from octane numbers have been removed and replaced with a brief analysis of the correlation between cetane numbers and octane numbers. The discussion on the accuracy and precision of the most commonly used methods for measuring cetane number has been expanded, and the data have been annotated extensively to provide additional information that will help the reader judge the relative reliability of individual results.« less

Distinguishing mechanisms for alternans in cardiac cells using constant-diastolic-interval pacing

NASA Astrophysics Data System (ADS)

Cherry, Elizabeth M.

2017-09-01

Alternans, a proarrhythmic dynamical state in which cardiac action potentials alternate between long and short durations despite a constant pacing period, traditionally has been explained at the cellular level using nonlinear dynamics principles under the assumption that the action potential duration (APD) is determined solely by the time elapsed since the end of the previous action potential, called the diastolic interval (DI). In this scenario, APDs at a steady state should be the same provided that the preceding DIs are the same. Nevertheless, experiments attempting to eliminate alternans by dynamically adjusting the timing of pacing stimuli to keep the DI constant showed that alternans persisted, contradicting the traditional theory. It is now widely known that alternans also can arise from a different mechanism associated with intracellular calcium cycling. Our goal is to determine whether intracellular calcium dynamics can explain the experimental findings regarding the persistence of alternans despite a constant DI. For this, we use mathematical models capable of producing alternans through both voltage- and calcium-mediated mechanisms. We show that for voltage-driven alternans, action potentials elicited from a constant-DI protocol are always the same. However, in the case of calcium-driven alternans, the constant-DI protocol can result in alternans. Reducing the strength of the calcium instability progressively reduces and finally eliminates constant-DI alternans. Our findings suggest that screening for the presence of alternans using a constant-DI protocol has the potential for differentiating between voltage-driven and calcium-driven alternans.

Dose equations for shift-variant CT acquisition modes using variable pitch, tube current, and aperture, and the meaning of their associated CTDI{sub vol}

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

Dixon, Robert L., E-mail: rdixon@wfubmc.edu; Boone, John M.; Kraft, Robert A.

2014-11-01

Purpose: With the increasing clinical use of shift-variant CT protocols involving tube current modulation (TCM), variable pitch or pitch modulation (PM), and variable aperture a(t), the interpretation of the scanner-reported CTDI{sub vol} is called into question. This was addressed for TCM in their previous paper published by Dixon and Boone [Med. Phys. 40, 111920 (14pp.) (2013)] and is extended to PM and concurrent TCM/PM as well as variable aperture in this work. Methods: Rigorous convolution equations are derived to describe the accumulated dose distributions for TCM, PM, and concurrent TCM/PM. A comparison with scanner-reported CTDI{sub vol} formulae clearly identifies themore » source of their differences with the traditional CTDI{sub vol}. Dose distribution simulations using the convolution are provided for a variety of TCM and PM scenarios including a helical shuttle used for perfusion studies (as well as constant mA)—all having the same scanner-reported CTDI{sub vol}. These new convolution simulations for TCM are validated by comparison with their previous discrete summations. Results: These equations show that PM is equivalent to TCM if the pitch variation p(z) is proportional to 1/i(z), where i(z) is the local tube current. The simulations show that the local dose at z depends only weakly on the local tube current i(z) or local pitch p(z) due to scatter from all other locations along z, and that the “local CTDI{sub vol}(z)” or “CTDI{sub vol} per slice” do not represent a local dose but rather only a relative i(z) or p(z). The CTDI-paradigm does not apply to shift-variant techniques and the scanner-reported CTDI{sub vol} for the same lacks physical significance and relevance. Conclusions: While the traditional CTDI{sub vol} at constant tube current and pitch conveys useful information (the peak dose at the center of the scan length), CTDI{sub vol} for shift-variant techniques (TCM or PM) conveys no useful information about the associated dose distribution it purportedly represents. On the other hand, the total energy absorbed E (“integral dose”) as well as its surrogate DLP remain robust (invariant) with respect to shift-variance, depending only on the total mAs = 〈i〉t{sub 0} accumulated during the total beam-on time t{sub 0} and aperture a, where 〈i〉 is the average current.« less

Temperature dependence of single-crystal elastic constants of flux-grown alpha-GaPO(4).

PubMed

Armand, P; Beaurain, M; Rufflé, B; Menaert, B; Papet, P

2009-06-01

The lattice parameter change with respect to temperature (T) has been measured using high-temperature powder X-ray diffraction techniques for high-temperature flux-grown GaPO(4) single crystals with the alpha-quartz structure. The lattice and the volume linear thermal expansion coefficients in the temperature range 303-1173 K were computed from the X-ray data. The percentage linear thermal expansions along the a and c axes at 1173 K are 1.5 and 0.51, respectively. The temperature dependence of the mass density rho of flux-grown GaPO(4) single crystals was evaluated using the volume thermal expansion coefficient alpha(V)(T) = 3.291 x 10(-5) - 2.786 x 10(-8) [T] + 4.598 x 10(-11)[T](2). Single-crystal high-resolution Brillouin spectroscopy measurements have been carried out at ambient pressure from 303 to 1123 K to determine the elastic constants C(IJ) of high-temperature flux-grown GaPO(4) material. The single-crystal elastic moduli were calculated using the sound velocities via the measured Brillouin frequency shifts Deltanu(B). These are, to our knowledge, the highest temperatures at which single-crystal elastic constants of alpha-GaPO(4) have been measured. Most of the room-temperature elastic constant values measured on flux-grown GaPO(4) material are higher than the ones found for hydrothermally grown GaPO(4) single crystals. The fourth-order temperature coefficients of both the Brillouin frequency shifts T(nuB)((n)) and the single-crystal elastic moduli T(C(IJ))((n)) were obtained. The first-order temperature coefficients of the C(IJ) are in excellent agreement with previous reports on low-temperature hydrothermally grown alpha-GaPO(4) single crystals, while small discrepancies in the higher-order temperature coefficients are observed. This is explained in terms of the OH content in the GaPO(4) network, which is an important parameter in the crystal thermal behavior.

Constant pressure mode extended simple gradient liquid chromatography system for micro and nanocolumns.

PubMed

Šesták, Jozef; Kahle, Vladislav

2014-07-11

Performing gradient liquid chromatography at constant pressure instead of constant flow rate has serious potential for shortening the analysis time and increasing the productivity of HPLC instruments that use gradient methods. However, in the constant pressure mode the decreasing column permeability during a long period of time negatively affects the repeatability of retention time. Thus a volume-based approach, in which the detector signal is plotted as a function of retention volume, must be taken into consideration. Traditional HPLC equipment, however, requires quite complex hardware and software modifications in order to work at constant pressure and in the volume-based mode. In this short communication, a low cost and easily feasible pressure-controlled extension of the previously described simple gradient liquid chromatography platform is proposed. A test mixture of four nitro esters was separated by 10-60% (v/v) acetone/water gradient and a high repeatability of retention volumes at 20MPa (RSD less than 0.45%) was realized. Separations were also performed at different values of pressure (20, 25, and 31MPa), and only small variations of the retention volumes (up to 0.8%) were observed. In this particular case, the gain in the analysis speed of 7% compared to the constant flow mode was realized at a constant pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Running vacuum in the Universe and the time variation of the fundamental constants of Nature

NASA Astrophysics Data System (ADS)

Fritzsch, Harald; Solà, Joan; Nunes, Rafael C.

2017-03-01

We compute the time variation of the fundamental constants (such as the ratio of the proton mass to the electron mass, the strong coupling constant, the fine-structure constant and Newton's constant) within the context of the so-called running vacuum models (RVMs) of the cosmic evolution. Recently, compelling evidence has been provided that these models are able to fit the main cosmological data (SNIa+BAO+H(z)+LSS+BBN+CMB) significantly better than the concordance Λ CDM model. Specifically, the vacuum parameters of the RVM (i.e. those responsible for the dynamics of the vacuum energy) prove to be nonzero at a confidence level ≳ 3σ . Here we use such remarkable status of the RVMs to make definite predictions on the cosmic time variation of the fundamental constants. It turns out that the predicted variations are close to the present observational limits. Furthermore, we find that the time evolution of the dark matter particle masses should be crucially involved in the total mass variation of our Universe. A positive measurement of this kind of effects could be interpreted as strong support to the "micro-macro connection" (viz. the dynamical feedback between the evolution of the cosmological parameters and the time variation of the fundamental constants of the microscopic world), previously proposed by two of us (HF and JS).

Role of dielectric constant in electrohydrodynamics of conducting fluids

NASA Technical Reports Server (NTRS)

Rhodes, Percy H.; Snyder, Robert S.; Roberts, Glyn O.

1992-01-01

Electrohydrodynamic (EHD) flows are driven by the interaction of an electric field with variations in electric conductivity or dielectric constant. In reported EHD experiments on the deformation of drops of immiscible dielectric fluids, the role of conductivity has tended to overshadow the role of dielectric constant. Often, large conductivity contrasts were convenient because the conductivities of the dielectric fluid were relatively uncertain. As a result, the observed effects were always qualitatively the same as if there had been no contrast in dielectric constant. Our early experiments studying the EHC deformations of cylindrical streams readily showed the conductivity effect but the dielectric constant effect was not discernible. We have modified our flow chamber and improved our method of observation and can now see an unequivocal dielectric constant effect which is in agreement with the prior theory. In this paper we first give a brief description of the physics of charge buildup at the interface of an immersed spherical drop or flowing cylindrical sample stream and then show how these charge distributions lead to interface distortions and accompanying viscous flows which constitute EHD. We next review theory and experiment describing the deformation of spherical drops. We show that in the reported drop deformation experiments, the contrast in dielectric constant was never sufficient to reverse the deformation due to the conductivity contrast. We review our work describing the deformation of a cylindrical stream of one fluid flowing in a parallel flow of another, and we compare the deformation equations with those for spherical drops. Finally, we show a definite experimental dielectric constant effect for cylindrical stream of aqueous polystyrene latex suspension. The dielectric constant varies with the frequency of the imposed electric field, and the associated EHD flow change is very apparent.

Limits on variations in fundamental constants from 21-cm and ultraviolet Quasar absorption lines.

PubMed

Tzanavaris, P; Webb, J K; Murphy, M T; Flambaum, V V; Curran, S J

2005-07-22

Quasar absorption spectra at 21-cm and UV rest wavelengths are used to estimate the time variation of x [triple-bond] alpha(2)g(p)mu, where alpha is the fine structure constant, g(p) the proton g factor, and m(e)/m(p) [triple-bond] mu the electron/proton mass ratio. Over a redshift range 0.24 < or = zeta(abs) < or = 2.04, (Deltax/x)(weighted)(total) = (1.17 +/- 1.01) x 10(-5). A linear fit gives x/x = (-1.43 +/- 1.27) x 10(-15) yr(-1). Two previous results on varying alpha yield the strong limits Deltamu/mu = (2.31 +/- 1.03) x 10(-5) and Deltamu/mu=(1.29 +/- 1.01) x10(-5). Our sample, 8 x larger than any previous, provides the first direct estimate of the intrinsic 21-cm and UV velocity differences 6 km s(-1).

BMP-driven NRF2 activation in esophageal basal cell differentiation and eosinophilic esophagitis

PubMed Central

Jiang, Ming; Ku, Wei-Yao; Zhou, Zhongren; Dellon, Evan S.; Falk, Gary W.; Nakagawa, Hiroshi; Wang, Mei-Lun; Liu, Kuancan; Wang, Jun; Katzka, David A.; Peters, Jeffrey H.; Lan, Xiaopeng; Que, Jianwen

2015-01-01

Tissue homeostasis requires balanced self-renewal and differentiation of stem/progenitor cells, especially in tissues that are constantly replenished like the esophagus. Disruption of this balance is associated with pathological conditions, including eosinophilic esophagitis (EoE), in which basal progenitor cells become hyperplastic upon proinflammatory stimulation. However, how basal cells respond to the inflammatory environment at the molecular level remains undetermined. We previously reported that the bone morphogenetic protein (BMP) signaling pathway is critical for epithelial morphogenesis in the embryonic esophagus. Here, we address how this pathway regulates tissue homeostasis and EoE development in the adult esophagus. BMP signaling was specifically activated in differentiated squamous epithelium, but not in basal progenitor cells, which express the BMP antagonist follistatin. Previous reports indicate that increased BMP activity promotes Barrett’s intestinal differentiation; however, in mice, basal progenitor cell–specific expression of constitutively active BMP promoted squamous differentiation. Moreover, BMP activation increased intracellular ROS levels, initiating an NRF2-mediated oxidative response during basal progenitor cell differentiation. In both a mouse EoE model and human biopsies, reduced squamous differentiation was associated with high levels of follistatin and disrupted BMP/NRF2 pathways. We therefore propose a model in which normal squamous differentiation of basal progenitor cells is mediated by BMP-driven NRF2 activation and basal cell hyperplasia is promoted by disruption of BMP signaling in EoE. PMID:25774506

On the vibrational spectra and structural parameters of methyl, silyl, and germyl azide from theoretical predictions and experimental data.

PubMed

Durig, Douglas T; Durig, M S; Durig, James R

2005-05-01

The infrared and Raman spectra of methyl, silyl, and germyl azide (XN3 where X=CH3, SiH3 and GeH3) have been predicted from ab initio calculations with full electron correlation by second order perturbation theory (MP2) and hybrid density function theory (DFT) by the B3LYP method with a variety of basis sets. These predicted data are compared to previously reported experimental data and complete vibrational assignments are provided for all three molecules. It is shown that several of the assignments recently proposed [J. Mol. Struct. (Theochem.) 434 (1998) 1] for methyl azide are not correct. Structural parameters for CH3N3 and GeH3N3 have been obtained by combining the previously reported microwave rotational constants with the ab initio MP2/6-311+G(d,p) predicted values. These "adjusted r0" parameters have very small uncertainties of +/-0.003 A for the XH distances and a maximum of +/-0.005 A for the heavy atom distances and +/-0.5 degrees for the angles. The predicted distance for the terminal NN bond which is nearly a triple bond is much better predicted by the B3LYP calculations, whereas the fundamental frequencies are better predicted by the scaled ab initio calculations. The results are discussed and compared to those obtained for some similar molecules.

Dielectric constant of atomic fluids with variable polarizability

PubMed Central

Alder, B. J.; Beers, J. C.; Strauss, H. L.; Weis, J. J.

1980-01-01

The Clausius-Mossotti function for the dielectric constant is expanded in terms of single atom and pair polarizabilities, leading to contributions that depend on both the trace and the anisotropy of the pair-polarizability tensor. The short-range contribution of the anisotropic part to the pair polarizabilities has previously been obtained empirically from light scattering experiments, whereas the trace contribution is now empirically determined by comparison to dielectric experiments. For helium, the short-range trace part agrees well with electronic structure calculations, whereas for argon qualitative agreement is achieved. PMID:16592830

Dielectric constant of atomic fluids with variable polarizability.

PubMed

Alder, B J; Beers, J C; Strauss, H L; Weis, J J

1980-06-01

The Clausius-Mossotti function for the dielectric constant is expanded in terms of single atom and pair polarizabilities, leading to contributions that depend on both the trace and the anisotropy of the pair-polarizability tensor. The short-range contribution of the anisotropic part to the pair polarizabilities has previously been obtained empirically from light scattering experiments, whereas the trace contribution is now empirically determined by comparison to dielectric experiments. For helium, the short-range trace part agrees well with electronic structure calculations, whereas for argon qualitative agreement is achieved.

Identification of forbidden vibration-rotation transitions in 15NH3

NASA Astrophysics Data System (ADS)

Urban, Š.; D'Cunha, Romola; Narahari Rao, K.

1984-07-01

Forbidden Δk - l = 3 vibration-rotation transitions have been observed in the ν4 band of 15NH3. The analysis of these transitions, together with previously published data on the allowed transitions, has made it possible to determine a set of molecular parameters, including for the first time the rotational constant C as well as the centrifugal distortion constants DK and HKKK, which are necessary for the calculation of energy levels. Some weak forbidden transitions in the ν2 band have also been observed.

Determination of the Gravitational Constant with a Beam Balance

NASA Astrophysics Data System (ADS)

Schlamminger, St.; Holzschuh, E.; Kündig, W.

2002-09-01

The Newtonian gravitational constant G was determined by means of a novel beam-balance experiment with an accuracy comparable to that of the most precise torsion-balance experiments. The gravitational force of two stainless steel tanks filled with 13 521kg mercury on 1.1kg test masses was measured using a commercial mass comparator. A careful analysis of the data and the experimental error yields G=6.674 07(22)×10-11 m3 kg-1 s-2. This value is in excellent agreement with most values previously obtained with different methods.

Understanding the atmospheric measurement and behavior of perfluorooctanoic acid.

PubMed

Webster, Eva M; Ellis, David A

2012-09-01

The recently reported quantification of the atmospheric sampling artifact for perfluorooctanoic acid (PFOA) was applied to existing gas and particle concentration measurements. Specifically, gas phase concentrations were increased by a factor of 3.5 and particle-bound concentrations by a factor of 0.1. The correlation constants in two particle-gas partition coefficient (K(QA)) estimation equations were determined for multiple studies with and without correcting for the sampling artifact. Correction for the sampling artifact gave correlation constants with improved agreement to those reported for other neutral organic contaminants, thus supporting the application of the suggested correction factors for perfluorinated carboxylic acids. Applying the corrected correlation constant to a recent multimedia modeling study improved model agreement with corrected, reported, atmospheric concentrations. This work confirms that there is sufficient partitioning to the gas phase to support the long-range atmospheric transport of PFOA. Copyright © 2012 SETAC.

Struvite recovery from swine waste biogas digester effluent through a stainless steel device under constant pH conditions.

PubMed

Perera, P W Anton; Wu, Wei-Xiang; Chen, Ying-Xu; Han, Zhi-Ying

2009-06-01

To investigate the struvite precipitation under constant and non-constant pH conditions and to test a stainless steel device under different operating regimes to maximize the recovery of struvite. The molar ratio of NH4+: Mg2+: PO4(3-) was adjusted to 1: 1.2: 1.2 and pH was elevated to 9.0. The absorbance measurement was used to trace the process of struvite crystallization. Wastewater and precipitate analysis was done by standard analytical methods. The pH constant experiment reported a significantly higher struvite precipitation (24.6 +/- 0.86 g) than the non-constant pH experiment (19.8 +/- 1.86 g). The SAR ranged from 5.6 to 8.2 g m(-2) h(-1) to 3.6-4.8 g m(-2) h(-1) in pH constant and non-constant experiments, respectively. The highest struvite deposit on the device was found in regime 3 followed by in regimes 2 and 4. The highest PO4(3-) (97.2%) and NH4+ (71%) removal was reported in the R1 regime. None of the influent Cu2+ or Zn2+ was precipitated on the device. A higher struvite yield is evident in pH constant experiments. Moreover, the stainless steel device facilitates the isolation of heavy metal free pure (around 96%) struvite from swine waste biogas digester effluent contaminated with cu2+ and Zn2+ and the highest yield is attainable with the device operating at 50 rpm with agitation by a magnetic stirrer.

Specific light uptake rates can enhance astaxanthin productivity in Haematococcus lacustris.

PubMed

Lee, Ho-Sang; Kim, Z-Hun; Park, Hanwool; Lee, Choul-Gyun

2016-05-01

Lumostatic operation was applied for efficient astaxanthin production in autotrophic Haematococcus lacustris cultures using 0.4-L bubble column photobioreactors. The lumostatic operation in this study was performed with three different specific light uptake rates (q(e)) based on cell concentration, cell projection area, and fresh weight as one-, two- and three-dimensional characteristics values, respectively. The q(e) value from the cell concentration (q(e1D)) obtained was 13.5 × 10⁻⁸ μE cell⁻¹ s⁻¹, and the maximum astaxanthin concentration was increased to 150 % compared to that of a control with constant light intensity. The other optimum q e values by cell projection area (q(e2D)) and fresh weight (q( e3D)) were determined to be 195 μE m⁻² s⁻¹ and 10.5 μE g⁻¹ s⁻¹ for astaxanthin production, respectively. The maximum astaxanthin production from the lumostatic cultures using the parameters controlled by cell projection area (2D) and fresh weight (3D) also increased by 36 and 22% over that of the controls, respectively. When comparing the optimal q e values among the three different types, the lumostatic cultures using q(e) based on fresh weight showed the highest astaxanthin productivity (22.8 mg L⁻¹ day⁻¹), which was a higher level than previously reported. The lumostatic operations reported here demonstrated that more efficient and effective astaxanthin production was obtained by H. lacustris than providing a constant light intensity, regardless of which parameter is used to calculate the specific light uptake rate.

Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex.

PubMed

Lu, Yao; Truccolo, Wilson; Wagner, Fabien B; Vargas-Irwin, Carlos E; Ozden, Ilker; Zimmermann, Jonas B; May, Travis; Agha, Naubahar S; Wang, Jing; Nurmikko, Arto V

2015-06-01

Transient gamma-band (40-80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions.

Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex

PubMed Central

Lu, Yao; Truccolo, Wilson; Wagner, Fabien B.; Vargas-Irwin, Carlos E.; Ozden, Ilker; Zimmermann, Jonas B.; May, Travis; Agha, Naubahar S.; Wang, Jing

2015-01-01

Transient gamma-band (40–80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions. PMID:25761956

Toward an understanding of the turbidity measurement of heterocoagulation rate constants of dispersions containing particles of different sizes.

PubMed

Liu, Jie; Xu, Shenghua; Sun, Zhiwei

2007-11-06

Our previous studies have shown that the determination of coagulation rate constants by turbidity measurement becomes impossible for a certain operating wavelength (that is, its blind point) because at this wavelength the change in the turbidity of a dispersion completely loses its response to the coagulation process. Therefore, performing the turbidity measurement in the wavelength range near the blind point should be avoided. In this article, we demonstrate that the turbidity measurement of the rate constant for coagulation of a binary dispersion containing particles of two different sizes (heterocoagulation) presents special difficulties because the blind point shifts with not only particle size but also with the component fraction. Some important aspects of the turbidity measurement for the heterocoagulation rate constant are discussed and experimentally tested. It is emphasized that the T-matrix method can be used to correctly evaluate extinction cross sections of doublets formed during the heterocoagulation process, which is the key data determining the rate constant from the turbidity measurement, and choosing the appropriate operating wavelength and component fraction are important to achieving a more accurate rate constant. Finally, a simple scheme in experimentally determining the sensitivity of the turbidity changes with coagulation over a wavelength range is proposed.

Unruh thermal hadronization and the cosmological constant

NASA Astrophysics Data System (ADS)

Frassino, Antonia M.; Bleicher, Marcus; Mann, Robert B.

2018-05-01

We use black holes with a negative cosmological constant to investigate aspects of the freeze-out temperature for hadron production in high energy heavy-ion collisions. The two black hole solutions present in the anti-de Sitter geometry have different mass and are compared to the data showing that the small black hole solution is in good agreement. This is a new feature in the literature since the small black hole in general relativity has different thermodynamic behavior from that of the large black hole solution. We find that the inclusion of the cosmological constant (which can be interpreted as the plasma pressure) leads to a lowering of the temperature of the freeze-out curve as a function of the baryochemical potential, improving the description previously suggested by Castorina, Kharzeev, and Satz.

Development of solar-driven electrochemical and photocatalytic water treatment system using a boron-doped diamond electrode and TiO2 photocatalyst.

PubMed

Ochiai, Tsuyoshi; Nakata, Kazuya; Murakami, Taketoshi; Fujishima, Akira; Yao, Yanyan; Tryk, Donald A; Kubota, Yoshinobu

2010-02-01

A high-performance, environmentally friendly water treatment system was developed. The system consists mainly of an electrochemical and a photocatalytic oxidation unit, with a boron-doped diamond (BDD) electrode and TiO(2) photocatalyst, respectively. All electric power for the mechanical systems and the electrolysis was able to be provided by photovoltaic cells. Thus, this system is totally driven by solar energy. The treatment ability of the electrolysis and photocatalysis units was investigated by phenol degradation kinetics. An observed rate constant of 5.1 x 10(-3)dm(3)cm(-2)h(-1) was calculated by pseudo-first-order kinetic analysis for the electrolysis, and a Langmuir-Hinshelwood rate constant of 5.6 microM(-1)min(-1) was calculated by kinetic analysis of the photocatalysis. According to previous reports, these values are sufficient for the mineralization of phenol. In a treatment test of river water samples, large amounts of chemical and biological contaminants were totally wet-incinerated by the system. This system could provide 12L/day of drinking water from the Tama River using only solar energy. Therefore, this system may be useful for supplying drinking water during a disaster. (c) 2009 Elsevier Ltd. All rights reserved.

A high-resolution photoelectron imaging and theoretical study of CP- and C2P-

NASA Astrophysics Data System (ADS)

Czekner, Joseph; Cheung, Ling Fung; Johnson, Eric L.; Fortenberry, Ryan C.; Wang, Lai-Sheng

2018-01-01

The discovery of interstellar anions has been a milestone in astrochemistry. In the search for new interstellar anions, CP- and C2P- are viable candidates since their corresponding neutrals have already been detected astronomically. However, scarce data exist for these negatively charged species. Here we report the electron affinities of CP and C2P along with the vibrational frequencies of their anions using high-resolution photoelectron imaging. These results along with previous spectroscopic data of the neutral species are used further to benchmark very accurate quartic force field quantum chemical methods that are applied to CP, CP-, C2P, and two electronic states of C2P-. The predicted electron affinities, vibrational frequencies, and rotational constants are in excellent agreement with the experimental data. The electron affinities of CP (2.8508 ± 0.0007 eV) and C2P (2.6328 ± 0.0006 eV) are measured accurately and found to be quite high, suggesting that the CP- and C2P- anions are thermodynamically stable and possibly observable. The current study suggests that the combination of high-resolution photoelectron imaging and quantum chemistry can be used to determine accurate molecular constants for exotic radical species of astronomical interest.

Revised Parameters for the AMOEBA Polarizable Atomic Multipole Water Model

PubMed Central

Pande, Vijay S.; Head-Gordon, Teresa; Ponder, Jay W.

2016-01-01

A set of improved parameters for the AMOEBA polarizable atomic multipole water model is developed. The protocol uses an automated procedure, ForceBalance, to adjust model parameters to enforce agreement with ab initio-derived results for water clusters and experimentally obtained data for a variety of liquid phase properties across a broad temperature range. The values reported here for the new AMOEBA14 water model represent a substantial improvement over the previous AMOEBA03 model. The new AMOEBA14 water model accurately predicts the temperature of maximum density and qualitatively matches the experimental density curve across temperatures ranging from 249 K to 373 K. Excellent agreement is observed for the AMOEBA14 model in comparison to a variety of experimental properties as a function of temperature, including the 2nd virial coefficient, enthalpy of vaporization, isothermal compressibility, thermal expansion coefficient and dielectric constant. The viscosity, self-diffusion constant and surface tension are also well reproduced. In comparison to high-level ab initio results for clusters of 2 to 20 water molecules, the AMOEBA14 model yields results similar to the AMOEBA03 and the direct polarization iAMOEBA models. With advances in computing power, calibration data, and optimization techniques, we recommend the use of the AMOEBA14 water model for future studies employing a polarizable water model. PMID:25683601

Examination of the effect of differential molecular diffusion in DNS of turbulent non-premixed flames

DOE PAGES

Han, Chao; Lignell, David O.; Hawkes, Evatt R.; ...

2017-02-09

Here, the effect of differential molecular diffusion (DMD) in turbulent non-premixed flames is studied by examining two previously reported DNS of temporally evolving planar jet flames, one with CO/H 2 as the fuel and the other with C 2H 4 as the fuel. The effect of DMD in the CO/H 2 DNS flames in which H 2 is part of fuel is found to behave similar to laminar flamelet, while in the C 2H 4 DNS flames in which H 2 is not present in the fuel it is similar to laminar flamelet in early stages but becomes different frommore » laminar flamelet later. The scaling of the effect of DMD with respect to the Reynolds number Re is investigated in the CO/H 2 DNS flames, and an evident power law scaling (~Re –a with a a positive constant) is observed. The scaling of the effect of DMD with respect to the Damkohler number Da is explored in both laminar counter-flow jet C 2H 4 diffusion flames and the C 2H 4 DNS flames. A power law scaling (~ Daa with a a positive constant) is clearly demonstrated for C 2H 4 nonpremixed flames.« less

Characterization of thermochromic VO2 (prepared at 250 °C) in a wide temperature range by spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Houska, J.; Kolenaty, D.; Rezek, J.; Vlcek, J.

2017-11-01

The paper deals with thermochromic VO2 prepared by reactive high-power impulse magnetron sputtering and characterized by spectroscopic ellipsometry. We focus on the dispersion of optical constants in a wide temperature range and on the transmittance predicted using the optical constants. While the thermochromic behavior of VO2 in itself has been reported previously (particularly above the room temperature, RT), in this paper we present (i) optical properties achieved at a low deposition temperature of 250 °C and without any substrate bias voltage (which dramatically increases the application potential of the coating) and (ii) changes of these properties not only above but also below RT (down to -30 °C). The properties include very low (for VO2) extinction coefficient at RT (0.10 at 550 nm), low transition temperature of around or even below 50 °C (compared to the frequently cited 68 °C) and high modulation of the predicted infrared transmittance (e.g. 39% at -30 °C, 30% at RT and 3.4% above the transition temperature at 2000 nm for a 100 nm thick coating on glass). The results are important for the design of thermochromic coatings, and pathways for their preparation under industry-friendly conditions, for various technological applications.

Extending the Constant Power Speed Range of the Brushless DC Motor through Dual Mode Inverter Control -- Part II: Laboratory Proof-of-Principle

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

Lawler, J.S.

2001-10-29

Previous theoretical work has shown that when all loss mechanisms are neglected the constant power speed range (CPSR) of a brushless dc motor (BDCM) is infinite when the motor is driven by the dual-mode inverter control (DMIC) [1,2]. In a physical drive, losses, particularly speed-sensitive losses, will limit the CPSR to a finite value. In this paper we report the results of laboratory testing of a low-inductance, 7.5-hp BDCM driven by the DMIC. The speed rating of the test motor rotor limited the upper speed of the testing, and the results show that the CPSR of the test machine ismore » greater than 6:1 when driven by the DMIC. Current wave shape, peak, and rms values remained controlled and within rating over the entire speed range. The laboratory measurements allowed the speed-sensitive losses to be quantified and incorporated into computer simulation models, which then accurately reproduce the results of lab testing. The simulator shows that the limiting CPSR of the test motor is 8:1. These results confirm that the DMIC is capable of driving low-inductance BDCMs over the wide CPSR that would be required in electric vehicle applications.« less

Human Manganese Superoxide Dismutase Tyrosine 34 Contribution to Structure and Catalysis

PubMed Central

Perry, J. Jefferson P.; Hearn, Amy S.; Cabelli, Diane E.; Nick, Harry S.; Tainer, John A.; Silverman, David N.

2009-01-01

Superoxide dismutase (SOD) enzymes are critical in controlling levels of reactive oxygen species (ROS) that are linked to aging, cancer and neurodegenerative disease. Superoxide (O2 •−) produced during respiration is removed by the product of the SOD2 gene, the homotetrameric manganese superoxide dismutase (MnSOD). Here, we examine the structural and catalytic roles of the highly conserved active-site residue Tyr34, based upon structure-function studies of MnSOD enzymes with mutations at this site. Substitution of Tyr34 with five different amino acids retained the active site protein structure and assembly, but causes a substantial decrease in the catalytic rate constant for the reduction of superoxide. The rate constant for formation of product inhibition complex also decreases but to a much lesser extent, resulting in a net increase in the product inhibition form of the mutant enzymes. Comparisons of crystal structures and catalytic rates also suggest that one mutation, Y34V, interrupts the hydrogen-bonded network, which is associated with a rapid dissociation of the product-inhibited complex. Notably, with three of the Tyr34 mutants we also observe an intermediate in catalysis, which has not been reported previously. Thus, these mutants establish a means to trap a catalytic intermediate that promises to help elucidate the mechanism of catalysis. PMID:19265433

A high-resolution photoelectron imaging and theoretical study of CP- and C2P.

PubMed

Czekner, Joseph; Cheung, Ling Fung; Johnson, Eric L; Fortenberry, Ryan C; Wang, Lai-Sheng

2018-01-28

The discovery of interstellar anions has been a milestone in astrochemistry. In the search for new interstellar anions, CP - and C 2 P - are viable candidates since their corresponding neutrals have already been detected astronomically. However, scarce data exist for these negatively charged species. Here we report the electron affinities of CP and C 2 P along with the vibrational frequencies of their anions using high-resolution photoelectron imaging. These results along with previous spectroscopic data of the neutral species are used further to benchmark very accurate quartic force field quantum chemical methods that are applied to CP, CP - , C 2 P, and two electronic states of C 2 P - . The predicted electron affinities, vibrational frequencies, and rotational constants are in excellent agreement with the experimental data. The electron affinities of CP (2.8508 ± 0.0007 eV) and C 2 P (2.6328 ± 0.0006 eV) are measured accurately and found to be quite high, suggesting that the CP - and C 2 P - anions are thermodynamically stable and possibly observable. The current study suggests that the combination of high-resolution photoelectron imaging and quantum chemistry can be used to determine accurate molecular constants for exotic radical species of astronomical interest.

Agarose electrophoresis of DNA in discontinuous buffers, using a horizontal slab apparatus and a buffer system with improved properties.

PubMed

Zsolnai, A; Orbán, L; Chrambach, A

1993-03-01

Using a horizontal slab apparatus with a buffer in the reservoirs at the level of the gel ("sea-level electrophoresis"), the retrograde discontinuous buffer system reported by Wiltfang et al. for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins was applied to DNA electrophoresis. This application yielded the advantages of an increased displacement rate of the moving boundary front and a decrease in the concentration of the counterion base in the resolving phase, which yielded reduced relative mobility values at equivalent gel concentrations and practicable low buffer concentrations. The change of relative mobilities (Rf) with a variation of field strength is decreased compared to that of the migration rate in the continuous Tris-boric-acid-EDTA (TBE) buffer and thus the robustness of the system is improved, as well as the efficiency of separation. The system of Wiltfang et al. has in common with previously described discontinuous DNA system, that it is able to stack DNA from dilute samples and is insensitive to sample components with lower net mobilities than DNA, such as acetate. However, the variance of Rf at constant current density in the discontinuous buffer system is not improved over that of the migration rate at constant field strength in the continuous TBE buffer.

Body temperature stability achieved by the large body mass of sea turtles.

PubMed

Sato, Katsufumi

2014-10-15

To investigate the thermal characteristics of large reptiles living in water, temperature data were continuously recorded from 16 free-ranging loggerhead turtles, Caretta caretta, during internesting periods using data loggers. Core body temperatures were 0.7-1.7°C higher than ambient water temperatures and were kept relatively constant. Unsteady numerical simulations using a spherical thermodynamic model provided mechanistic explanations for these phenomena, and the body temperature responses to fluctuating water temperature can be simply explained by a large body mass with a constant thermal diffusivity and a heat production rate rather than physiological thermoregulation. By contrast, body temperatures increased 2.6-5.1°C in 107-152 min during their emergences to nest on land. The estimated heat production rates on land were 7.4-10.5 times the calculated values in the sea. The theoretical prediction that temperature difference between body and water temperatures would increase according to the body size was confirmed by empirical data recorded from several species of sea turtles. Comparing previously reported data, the internesting intervals of leatherback, green and loggerhead turtles were shorter when the body temperatures were higher. Sea turtles seem to benefit from a passive thermoregulatory strategy, which depends primarily on the physical attributes of their large body masses. © 2014. Published by The Company of Biologists Ltd.

Revised estimates for ozone reduction by shuttle operation

NASA Technical Reports Server (NTRS)

Potter, A. E.

1978-01-01

Previous calculations by five different modeling groups of the effect of space shuttle operations on the ozone layer yielded an estimate of 0.2 percent ozone reduction for the Northern Hemisphere at 60 launches per year. Since these calculations were made, the accepted rate constant for the reaction between hydroperoxyl and nitric oxide to yield hydroxyl and nitrogen dioxide, HO2 + NO yields OH + NO2, was revised upward by more than an order of magnitude, with a resultant increase in the predicted ozone reduction for chlorofluoromethanes by a factor of approximately 2. New calculations of the shuttle effect were made with use of the new rate constant data, again by five different modeling groups. The new value of the shuttle effect on the ozone layer was found to be 0.25 percent. The increase resulting from the revised rate constant is considerably less for space shuttle operations than for chlorofluoromethane production, because the new rate constant also increases the calculated rate of downward transport of shuttle exhaust products out of the stratosphere.

Stiffness-constant variation in nickel-based alloys: Experiment and theory

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

Hennion, M.; Hennion, B.

1979-01-01

Recent measurements of the spin-wave stiffness constant in several nickel alloys at various concentrations are interpreted within a random-phase approximation, coherent-potential approximation (RPA-CPA) band model which uses the Hartree-Fock approximation to treat the intraatomic correlations. We give a theoretical description of the possible impurity states in the Hartree-Fock approximation. This allows the determination of the Hartree-Fock solutions which can account for the stiffness-constant behavior and the magnetic moment on the impurity for all the investigated alloys. For alloys such as NiCr, NiV, NiMo, and NiRu, the magnetizations of which deviate from the Slater-Pauling curve, our determination does not correspond tomore » previous works and is consequently discussed. The limits of the model appear mainly due to local-environment effects; in the case of NiMn, it is found that a ternary-alloy model with some Mn atoms in the antiferromagnetic state can account for both stiffness-constant and magnetization behaviors.« less

Vertex Algebras W(p)Am and W(p)Dm and Constant Term Identities

NASA Astrophysics Data System (ADS)

Adamović, Dražen; Lin, Xianzu; Milas, Antun

2015-03-01

We consider AD-type orbifolds of the triplet vertex algebras W(p) extending the well-known c=1 orbifolds of lattice vertex algebras. We study the structure of Zhu's algebras A(W(p)^{A_m}) and A(W(p)^{D_m}), where A_m and D_m are cyclic and dihedral groups, respectively. A combinatorial algorithm for classification of irreducible W(p)^Γ-modules is developed, which relies on a family of constant term identities and properties of certain polynomials based on constant terms. All these properties can be checked for small values of m and p with a computer software. As a result, we argue that if certain constant term properties hold, the irreducible modules constructed in [Commun. Contemp. Math. 15 (2013), 1350028, 30 pages; Internat. J. Math. 25 (2014), 1450001, 34 pages] provide a complete list of irreducible W(p)^{A_m} and W(p)^{D_m}-modules. This paper is a continuation of our previous work on the ADE subalgebras of the triplet vertex algebra W(p).

A single fracture toughness parameter for fibrous composite laminates

NASA Technical Reports Server (NTRS)

Poe, C. C., Jr.

1981-01-01

A general fracture toughness parameter Qc was previously derived and verified to be a material constant, independent of layup, for centrally cracked boron aluminum composite specimens. The specimens were made with various proportions of 0 and + or - 45 degree plies. A limited amount of data indicated that the ratio Qc/epsilon tuf' where epsilon tuf is the ultimate tensile strain of the fibers, might be a constant for all composite laminates, regardless of material and layup. In that case, a single value of Qc/epsilon tuf could be used to predict the fracture toughness of all fibrous composite laminates from only the elastic constants and epsilon tuf. Values of Qc/epsilon tuf were calculated for centrally cracked specimens made from graphite/polyimide, graphite/epoxy, E glass/epoxy, boron/epoxy, and S glass graphite/epoxy materials with numerous layups. Within ordinary scatter, the data indicate that Qc/epsilon tuf is a constant for all laminates that did not split extensively at the crack tips or have other deviate failure modes.

Hyperfine Structure Constants of Energetically High-lying Levels of Odd Parity of Atomic Vanadium

NASA Astrophysics Data System (ADS)

Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü.

2014-09-01

High-resolution Fourier transform spectra of a vanadium-argon plasma have been recorded in the wavelength range of 365-670 nm (15,000-27,400 cm-1). Optical bandpass filters were used in the experimental setup to enhance the sensitivity of the Fourier transform spectrometer. In total, 138 atomic vanadium spectral lines showing resolved or partially resolved hyperfine structure have been analyzed to determine the magnetic dipole hyperfine structure constants A of the involved energy levels. One of the investigated lines has not been previously classified. As a result, the magnetic dipole hyperfine structure constants A for 90 energy levels are presented: 35 of them belong to the configuration 3d 34s4p and 55 to the configuration 3d 44p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d 34s4p and 44 to 3d 44p.

Improved resolution of single channel dwell times reveals mechanisms of binding, priming, and gating in muscle AChR

PubMed Central

Mukhtasimova, Nuriya; daCosta, Corrie J.B.

2016-01-01

The acetylcholine receptor (AChR) from vertebrate skeletal muscle initiates voluntary movement, and its kinetics of activation are crucial for maintaining the safety margin for neuromuscular transmission. Furthermore, the kinetic mechanism of the muscle AChR serves as an archetype for understanding activation mechanisms of related receptors from the Cys-loop superfamily. Here we record currents through single muscle AChR channels with improved temporal resolution approaching half an order of magnitude over our previous best. A range of concentrations of full and partial agonists are used to elicit currents from human wild-type and gain-of-function mutant AChRs. For each agonist–receptor combination, rate constants are estimated from maximum likelihood analysis using a kinetic scheme comprised of agonist binding, priming, and channel gating steps. The kinetic scheme and rate constants are tested by stochastic simulation, followed by incorporation of the experimental step response, sampling rate, background noise, and filter bandwidth. Analyses of the simulated data confirm all rate constants except those for channel gating, which are overestimated because of the established effect of noise on the briefest dwell times. Estimates of the gating rate constants were obtained through iterative simulation followed by kinetic fitting. The results reveal that the agonist association rate constants are independent of agonist occupancy but depend on receptor state, whereas those for agonist dissociation depend on occupancy but not on state. The priming rate and equilibrium constants increase with successive agonist occupancy, and for a full agonist, the forward rate constant increases more than the equilibrium constant; for a partial agonist, the forward rate and equilibrium constants increase equally. The gating rate and equilibrium constants also increase with successive agonist occupancy, but unlike priming, the equilibrium constants increase more than the forward rate constants. As observed for a full and a partial agonist, the gain-of-function mutation affects the relationship between rate and equilibrium constants for priming but not for channel gating. Thus, resolving brief single channel currents distinguishes priming from gating steps and reveals how the corresponding rate and equilibrium constants depend on agonist occupancy. PMID:27353445

Comparative genomic survey of microbial arylamine N-acetyltransferases

USDA-ARS?s Scientific Manuscript database

Introduction: Microorganisms are constantly exposed to exogenous chemical influences. Our previous genomic surveys have identified putative NAT genes across a phylogenetic spectrum of prokaryotic and eukaryotic microorganisms. We are currently pursuing two lines of investigation: The first looks int...

Comparison of thiaminase activity in fish using the radiometric and 4-nitrothiophenol colorimetric methods

USGS Publications Warehouse

Honeyfield, D.C.; Hanes, J.W.; Brown, L.; Kraft, C.E.; Begley, T.P.

2010-01-01

Thiaminase induced thiamine deficiency occurs in fish, humans, livestock and wild animals. A non-radioactive thiaminase assay was described in 2007, but a direct comparison with the radioactive 14C-thiamine method which has been in use for more than 30years has not been reported. The objective was to measure thiaminase activity in forage fish (alewife Alosa pseudoharengus, rainbow smelt Osmerus mordax, and slimy sculpin Cottus cognatus) consumed by predators that manifest thiamine deficiency using both methods. Modifications were made to the colorimetric assay to improve repeatability. Modification included a change in assay pH, enhanced sample clean-up, constant assay temperature (37??C), increase in the concentration of 4-nitrothiophenol (4NTP) and use of a spectrophotometer fitted with a 0.2cm cell. A strong relationship between the two assays was found for 51 alewife (R2=0.85), 36 smelt (R2=0.87) and 20 sculpin (R2=0.82). Thiaminase activity in the colorimetric assay was about 1000 times higher than activity measured by the radioactive method. Application of the assay to fish species from which no thiaminase activity has previously been reported resulted in no 4NTP thiaminase activity being found in bloater Coregonus hoyi, lake trout Salvelinus namaycusch, steelhead trout Oncorhynchus mykiss or Chinook salmon Oncorhynchus tshawytscha. In species previously reported to contain thiaminase, 4NTP thiaminase activity was measured in bacteria Paenibacillus thiaminolyticus, gizzard shad Dorosoma cepedianum, bracken fern Pteridium aquilinum, quagga mussel Dreissena bugensis and zebra mussels D. polymorpha. ?? 2010.

Superconductivity in the Nb-Ru-Ge σ phase

DOE PAGES

Carnicom, Elizabeth M.; Xie, Weiwei; Sobczak, Zuzanna; ...

2017-12-07

Here, we show that the previously unreported ternary σ-phase material Nb 20.4Ru 5.7Ge 3.9 (Nb 0.68Ru 0.19Ge 0.13) is a superconductor with a critical temperature of 2.2 K. Temperature-dependent magnetic susceptibility, resistance, and specific heat measurements were used to characterize the superconducting transition. The Sommerfeld constant γ for Nb 20.4Ru 5.7Ge 3.9 is 91 mJ mol-f.u. -1K -2 (~3 mJ mol-atom -1K -2) and the specific heat anomaly at the superconducting transition, ΔC/γT c, is approximately 1.38. The zero-temperature upper critical field (µ 0Hc 2(0)) was estimated to be 2 T by resistance data. Field-dependent magnetization data analysis estimated µmore » 0Hc 1(0) to be 5.5 mT. Thus, the characterization shows Nb 20.4Ru 5.7Ge 3.9 to be a type II BCS superconductor. This material appears to be the first reported ternary phase in the Nb-Ru-Ge system, and the fact that there are no previously reported binary Nb-Ru, Nb-Ge, or Ru-Ge σ-phases shows that all three elements are necessary to stabilize the material. An analogous σ-phase in the Ta-Ru-Ge system did not display superconductivity above 1.7 K, which suggests that electron count cannot govern the superconductivity observed. Preliminary characterization of a possible superconducting σ-phase in the Nb-Ru-Ga system is also reported.« less

Comparison between variable and constant rotor speed operation on WINDMEL-II

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

Sasamoto, Akira; Matsumiya, Hikaru; Kawamura, Shunji

1996-10-01

On a wind turbine control system for rotor revolution speed, it is believed that variable speed operation has the advantages over constant speed from a view point of both aerodynamics and mechanics. However, there is no experimental study which shows the differences. In this report, the authors intend to clarify the differences about shaft torque by using experimental data, from a new wind turbine system which has both variable and constant operation. The result in observation of the experimental data shows that variable speed operational shaft torque is lower than constant speed operational one.

Environmental Fate Studies on Certain Munition Wastewater Constituents - Literature Review

DTIC Science & Technology

1980-03-01

gram-negative bacteria , actinaycetes, yeasts, and fungi. They found that TNT at 50 Mgtter severely inhibited the growth of these organisms in wost...i , conditions . I Biodegradation ,. Chambers et al. (1963) reported evidence of degradation of 2,4-DNT with phenol-adapted bacteria and 100 mg/liter...coefficient based on organic carbon contentoc H - Henry’s Law constant kA - Hydrolysis rate constant under acidic conditions k.M - Hydrolysis rate constant

Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions.

PubMed

Jentschura, Ulrich D; Mohr, Peter J; Tan, Joseph N; Wundt, Benedikt J

2008-04-25

A comparison of precision frequency measurements to quantum electrodynamics (QED) predictions for Rydberg states of hydrogenlike ions can yield information on values of fundamental constants and test theory. With the results of a calculation of a key QED contribution reported here, the uncertainty in the theory of the energy levels is reduced to a level where such a comparison can yield an improved value of the Rydberg constant.

Updated radiometric calibration for the Landsat-5 thematic mapper reflective bands

USGS Publications Warehouse

Helder, D.L.; Markham, B.L.; Thome, K.J.; Barsi, J.A.; Chander, G.; Malla, R.

2008-01-01

The Landsat-5 Thematic Mapper (TM) has been the workhorse of the Landsat system. Launched in 1984, it continues collecting data through the time frame of this paper. Thus, it provides an invaluable link to the past history of the land features of the Earth's surface, and it becomes imperative to provide an accurate radiometric calibration of the reflective bands to the user community. Previous calibration has been based on information obtained from prelaunch, the onboard calibrator, vicarious calibration attempts, and cross-calibration with Landsat-7. Currently, additional data sources are available to improve this calibration. Specifically, improvements in vicarious calibration methods and development of the use of pseudoinvariant sites for trending provide two additional independent calibration sources. The use of these additional estimates has resulted in a consistent calibration approach that ties together all of the available calibration data sources. Results from this analysis indicate a simple exponential, or a constant model may be used for all bands throughout the lifetime of Landsat-5 TM. Where previously time constants for the exponential models were approximately one year, the updated model has significantly longer time constants in bands 1-3. In contrast, bands 4, 5, and 7 are shown to be best modeled by a constant. The models proposed in this paper indicate calibration knowledge of 5% or better early in life, decreasing to nearly 2% later in life. These models have been implemented at the U.S. Geological Survey Earth Resources Observation and Science (EROS) and are the default calibration used for all Landsat TM data now distributed through EROS. ?? 2008 IEEE.

Elastic constants and dynamics in nematic liquid crystals

NASA Astrophysics Data System (ADS)

Humpert, Anja; Allen, Michael P.

2015-09-01

In this paper, we present molecular dynamics calculations of the Frank elastic constants, and associated time correlation functions, in nematic liquid crystals. We study two variants of the Gay-Berne potential, and use system sizes of half a million molecules, significantly larger than in previous studies of elastic behaviour. Equilibrium orientational fluctuations in reciprocal (k-) space were calculated, to determine the elastic constants by fitting at low |k|; our results indicate that small system size may be a source of inaccuracy in previous work. Furthermore, the dynamics of the Gay-Berne nematic were studied by calculating time correlation functions of components of the order tensor, together with associated components of the velocity field, for a set of wave vectors k. Confirming our earlier work, we found exponential decay for splay and twist correlations, and oscillatory exponential decay for the bend correlation. In this work, we confirm similar behaviour for the corresponding velocity components. In all cases, the decay rates, and oscillation frequencies, were found to be accurately proportional to k2 for small k, as predicted by the equations of nematodynamics. However, the observation of oscillatory bend fluctuations, and corresponding oscillatory shear flow decay, is in contradiction to the usual assumptions appearing in the literature, and in standard texts. We discuss the advantages and drawbacks of using large systems in these calculations.

Non-contact AFM measurement of the Hamaker constants of solids: Calibrating cantilever geometries.

PubMed

Fronczak, Sean G; Browne, Christopher A; Krenek, Elizabeth C; Beaudoin, Stephen P; Corti, David S

2018-05-01

Surface effects arising from roughness and deformation can negatively affect the results of AFM contact experiments. Using the non-contact portion of an AFM deflection curve is therefore desirable for estimating the Hamaker constant, A, of a solid material. A previously validated non-contact quasi-dynamic method for estimating A is revisited, in which the cantilever tip is now always represented by an "effective sphere". In addition to simplifying this previous method, accurate estimates of A can still be obtained even though precise knowledge of the nanoscale geometric features of the cantilever tip are no longer required. The tip's "effective" radius of curvature, R eff , is determined from a "calibration" step, in which the tip's deflection at first contact with the surface is measured for a substrate with a known Hamaker constant. After R eff is known for a given tip, estimates of A for other surfaces of interest are then determined. An experimental study was conducted to validate the new method and the obtained results are in good agreement with predictions from the Lifshitz approximation, when available. Since R eff accounts for all geometric uncertainties of the tip through a single fitted parameter, no visual fitting of the tip shape was required. Copyright © 2018 Elsevier Inc. All rights reserved.

Evaluating the use of twitter as a tool to increase engagement in medical education.

PubMed

Diug, Basia; Kendal, Evie; Ilic, Dragan

2016-01-01

Social media is regularly used by undergraduate students. Twitter has a constant feed to the most current research, news and opinions of experts as well as organisations. Limited evidence exists that examines how to use social media platforms, such as Twitter, effectively in medical education. Furthermore, there is limited evidence to inform educators regarding social media's potential to increase student interaction and engagement. To evaluate whether social media, in particular Twitter, can be successfully used as a pedagogical tool in an assessment to increase student engagement with staff, peers and course content. First year biomedical science students at Monash University completing a core public health unit were recruited into the study. Twitter-related activities were incorporated into the semester long unit and aligned with both formative and summative assessments. Students completed a structured questionnaire detailing previous use of social media and attitudes towards its use in education post engagement in the Twitter-specific activities. Likert scale responses compared those who participated in the Twitter activities with those who did not using student's t-test. A total of 236 (79.4%) of invited students participated in the study. Among 90% of students who reported previous use of social media, 87.2% reported using Facebook, while only 13.1% reported previous use of Twitter. Social media was accessed most commonly through a mobile device (49.1%). Students actively engaging in Twitter activities had significantly higher end-of-semester grades compared with those who did not [Mean Difference (MD) = 3.98, 95% CI 0.40, 7.55]. Students perceived that the use of Twitter enabled greater accessibility to staff, was a unique method of promoting public health, and facilitated collaboration with peers. Use of social media as an additional, or alternate, teaching intervention is positively supported by students. Specific use of micro-blogs such as Twitter can promote greater student-staff engagement by developing an ongoing academic conversation.

The Rate Constant for the Reaction H + C2H5 at T = 295 - 150K

NASA Technical Reports Server (NTRS)

Pimentel, Andre S.; Payne, Walter A.; Nesbitt, Fred L.; Cody, Regina J.; Stief, Louis J.

2004-01-01

The reaction between the hydrogen atom and the ethyl (C2H3) radical is predicted by photochemical modeling to be the most important loss process for C2H5 radicals in the atmospheres of Jupiter and Saturn. This reaction is also one of the major sources for the methyl radicals in these atmospheres. These two simplest hydrocarbon radicals are the initial species for the synthesis of larger hydrocarbons. Previous measurements of the rate constant for the H + C2H5 reaction varied by a factor of five at room temperature, and some studies showed a dependence upon temperature while others showed no such dependence. In addition, the previous studies were at higher temperatures and generally higher pressures than that needed for use in planetary atmospheric models. The rate constant for the reaction H + C2H5 has been measured directly at T = 150, 202 and 295 K and at P = 1.0 Torr He for all temperatures and additionally at P = 0.5 and 2.0 Torr He at T = 202 K. The measurements were performed in a discharge - fast flow system. The decay of the C2H5 radical in the presence of excess hydrogen was monitored by low-energy electron impact mass spectrometry under pseudo-first order conditions. H atoms and C2H5 radicals were generated rapidly and simultaneously by the reaction of fluorine atoms with H2 and C2H6, respectively. The total rate constant was found to be temperature and pressure independent. The measured total rate constant at each temperature are: k(sub 1)(295K) = (1.02+/-0.24)x10(exp -10), k(sub 1)(202K) = (1.02+/-0.22)x10(exp -10) and k(sub 1)(150K) = (0.93+/-0.21)x10(exp -10), all in units of cu cm/molecule/s. The total rate constant derived from all the combined measurements is k(sub 1) = (l.03+/-0.17)x10(exp -10) cu cm/molecule/s. At room temperature our results are about a factor of two higher than the recommended rate constant and a factor of three lower than the most recently published study.

A novel frame-level constant-distortion bit allocation for smooth H.264/AVC video quality

NASA Astrophysics Data System (ADS)

Liu, Li; Zhuang, Xinhua

2009-01-01

It is known that quality fluctuation has a major negative effect on visual perception. In previous work, we introduced a constant-distortion bit allocation method [1] for H.263+ encoder. However, the method in [1] can not be adapted to the newest H.264/AVC encoder directly as the well-known chicken-egg dilemma resulted from the rate-distortion optimization (RDO) decision process. To solve this problem, we propose a new two stage constant-distortion bit allocation (CDBA) algorithm with enhanced rate control for H.264/AVC encoder. In stage-1, the algorithm performs RD optimization process with a constant quantization QP. Based on prediction residual signals from stage-1 and target distortion for smooth video quality purpose, the frame-level bit target is allocated by using a close-form approximations of ratedistortion relationship similar to [1], and a fast stage-2 encoding process is performed with enhanced basic unit rate control. Experimental results show that, compared with original rate control algorithm provided by H.264/AVC reference software JM12.1, the proposed constant-distortion frame-level bit allocation scheme reduces quality fluctuation and delivers much smoother PSNR on all testing sequences.

Bottom-up driven involuntary auditory evoked field change: constant sound sequencing amplifies but does not sharpen neural activity.

PubMed

Okamoto, Hidehiko; Stracke, Henning; Lagemann, Lothar; Pantev, Christo

2010-01-01

The capability of involuntarily tracking certain sound signals during the simultaneous presence of noise is essential in human daily life. Previous studies have demonstrated that top-down auditory focused attention can enhance excitatory and inhibitory neural activity, resulting in sharpening of frequency tuning of auditory neurons. In the present study, we investigated bottom-up driven involuntary neural processing of sound signals in noisy environments by means of magnetoencephalography. We contrasted two sound signal sequencing conditions: "constant sequencing" versus "random sequencing." Based on a pool of 16 different frequencies, either identical (constant sequencing) or pseudorandomly chosen (random sequencing) test frequencies were presented blockwise together with band-eliminated noises to nonattending subjects. The results demonstrated that the auditory evoked fields elicited in the constant sequencing condition were significantly enhanced compared with the random sequencing condition. However, the enhancement was not significantly different between different band-eliminated noise conditions. Thus the present study confirms that by constant sound signal sequencing under nonattentive listening the neural activity in human auditory cortex can be enhanced, but not sharpened. Our results indicate that bottom-up driven involuntary neural processing may mainly amplify excitatory neural networks, but may not effectively enhance inhibitory neural circuits.

Transition state theory thermal rate constants and RRKM-based branching ratios for the N((2)D) + CH(4) reaction based on multi-state and multi-reference ab initio calculations of interest for the Titan's chemistry.

PubMed

Ouk, Chanda-Malis; Zvereva-Loëte, Natalia; Scribano, Yohann; Bussery-Honvault, Béatrice

2012-10-30

Multireference single and double configuration interaction (MRCI) calculations including Davidson (+Q) or Pople (+P) corrections have been conducted in this work for the reactants, products, and extrema of the doublet ground state potential energy surface involved in the N((2)D) + CH(4) reaction. Such highly correlated ab initio calculations are then compared with previous PMP4, CCSD(T), W1, and DFT/B3LYP studies. Large relative differences are observed in particular for the transition state in the entrance channel resolving the disagreement between previous ab initio calculations. We confirm the existence of a small but positive potential barrier (3.86 ± 0.84 kJ mol(-1) (MR-AQCC) and 3.89 kJ mol(-1) (MRCI+P)) in the entrance channel of the title reaction. The correlation is seen to change significantly the energetic position of the two minima and five saddle points of this system together with the dissociation channels but not their relative order. The influence of the electronic correlation into the energetic of the system is clearly demonstrated by the thermal rate constant evaluation and it temperature dependance by means of the transition state theory. Indeed, only MRCI values are able to reproduce the experimental rate constant of the title reaction and its behavior with temperature. Similarly, product branching ratios, evaluated by means of unimolecular RRKM theory, confirm the NH production of Umemoto et al., whereas previous works based on less accurate ab initio calculations failed. We confirm the previous findings that the N((2)D) + CH(4) reaction proceeds via an insertion-dissociation mechanism and that the dominant product channels are CH(2)NH + H and CH(3) + NH. Copyright © 2012 Wiley Periodicals, Inc.

Pressure in isochoric systems containing aqueous solutions at subzero Centigrade temperatures.

PubMed

Ukpai, Gideon; Năstase, Gabriel; Șerban, Alexandru; Rubinsky, Boris

2017-01-01

Preservation of biological materials at subzero Centigrade temperatures, cryopreservation, is important for the field of tissue engineering and organ transplantation. Our group is studying the use of isochoric (constant volume) systems of aqueous solution for cryopreservation. Previous studies measured the pressure-temperature relations in aqueous isochoric systems in the temperature range from 0°C to - 20°C. The goal of this study is to expand the pressure-temperature measurement beyond the range reported in previous publications. To expand the pressure-temperature measurements beyond the previous range, we have developed a new isochoric device capable of withstanding liquid nitrogen temperatures and pressures of up to 413 MPa. The device is instrumented with a pressure transducer than can monitor and record the pressures in the isochoric chamber in real time. Measurements were made in a temperature range from - 5°C to liquid nitrogen temperatures for various solutions of pure water and Me2SO (a chemical additive used for protection of biological materials in a frozen state and for vitrification (glass formation) of biological matter). Undissolved gaseous are is carefully removed from the system. Temperature-pressure data from - 5°C to liquid nitrogen temperature for pure water and other solutions are presented in this study. Following are examples of some, temperature-pressure values, that were measured in an isochoric system containing pure water: (- 20°C, 187 MPa); (-25°C, 216 MPa); (- 30°C, 242.3 MPa); (-180°C, 124 MPa). The data is consistent with the literature, which reports that the pressure and temperature at the triple point, between ice I, ice III and water is, - 21.993°C and 209.9 MPa, respectively. It was surprising to find that the pressure in the isochoric system increases at temperatures below the triple point and remains high to liquid nitrogen temperatures. Measurements of pressure-temperature relations in solutions of pure water and Me2SO in different concentrations show that, for concentrations in which vitrification is predicted, no increase in pressure was measured during rapid cooling to liquid nitrogen temperatures. However, ice formation either during cooling or warming to and from liquid nitrogen temperatures produced an increase in pressure. The data obtained in this study can be used to aid in the design of isochoric cryopreservation protocols. The results suggest that the pressure measurement is important in the design of "constant volume" systems and can provide a simple means to gain information on the occurrence of vitrification and devitrification during cryopreservation processes of aqueous solutions in an isochoric system.

Potassium ions in SiO2: electrets for silicon surface passivation

NASA Astrophysics Data System (ADS)

Bonilla, Ruy S.; Wilshaw, Peter R.

2018-01-01

This manuscript reports an experimental and theoretical study of the transport of potassium ions in thin silicon dioxide films. While alkali contamination was largely researched in the context of MOSFET instability, recent reports indicate that potassium ions can be embedded into oxide films to produce dielectric materials with permanent electric charge, also known as electrets. These electrets are integral to a number of applications, including the passivation of silicon surfaces for optoelectronic devices. In this work, electric field assisted migration of ions is used to rapidly drive K+ into SiO2 and produce effective passivation of silicon surfaces. Charge concentrations of up to ~5  ×  1012 e cm-2 have been achieved. This charge was seen to be stable for over 1500 d, with decay time constants as high as 17 000 d, producing an effectively passivated oxide-silicon interface with SRV  <  7 cm s-1, in 1 Ω cm n-type material. This level of charge stability and passivation effectiveness has not been previously reported. Overall, this is a new and promising methodology to enhance surface passivation for the industrial manufacture of silicon optoelectronic devices.

Comparing the actions of lanicemine and ketamine in depression: key role of the anterior cingulate.

PubMed

Downey, Darragh; Dutta, Arpan; McKie, Shane; Dawson, Gerard R; Dourish, Colin T; Craig, Kevin; Smith, Mark A; McCarthy, Dennis J; Harmer, Catherine J; Goodwin, Guy M; Williams, Steve; Deakin, J F William

2016-06-01

Intravenous infusion of lanicemine (formerly AZD6765), a low trapping non-selective N-methyl-D-aspartate (NMDA) receptor antagonist, induces antidepressant effects with a similar time course to ketamine. We investigated whether a single dose lanicemine infusion would reproduce the previously reported decrease in subgenual anterior cingulate cortex (sgACC) activity evoked by ketamine, a potential mechanism of antidepressant efficacy. Sixty un-medicated adults meeting the criteria for major depressive disorder were randomly assigned to receive constant intravenous infusions of ketamine, lanicemine or saline during a 60min pharmacological magnetic resonance imaging (phMRI) scan. Both ketamine and lanicemine gradually increased the blood oxygen level dependent signal in sgACC and rostral ACC as the primary outcome measure. No decreases in signal were seen in any region. Interviewer-rated psychotic and dissociative symptoms were minimal following administration of lanicemine. There was no significant antidepressant effect of either infusion compared to saline. The previously reported deactivation of sgACC after ketamine probably reflects the rapid and pronounced subjective effects evoked by the bolus-infusion method used in the previous study. Activation of the ACC was observed following two different NMDA compounds in both Manchester and Oxford using different 3T MRI scanners, and this effect predicted improvement in mood 1 and 7 days post-infusion. These findings suggest that the initial site of antidepressant action for NMDA antagonists may be the ACC (NCT01046630. A Phase I, Multi-centre, Double-blind, Placebo-controlled Parallel Group Study to Assess the pharmacoMRI Effects of AZD6765 in Male and Female Subjects Fulfilling the Criteria for Major Depressive Disorder; http://clinicaltrials.gov/show/NCT01046630). Copyright © 2016 Elsevier B.V. and ECNP. All rights reserved.

Re-Evaluation of Ar-39 - Ar-40 Ages for Apollo Lunar Rocks 15415 and 60015

NASA Technical Reports Server (NTRS)

Park, J.; Nyquist, L. E.; Bogard, D. D.; Garrison, D. H.; Shih, C.-Y.

2010-01-01

We re-analyzed 39Ar-40Ar ages of Apollo lunar highland samples 15415 and 60015, two ferroan anorthosites analyzed previously in the 1970 s, with a more detailed approach and with revised decay constants. From these samples we carefully prepared 100-200 mesh mineral separates for analysis at the Noble Gas Laboratory at NASA-Johnson Space Center. The Ar-39-Ar-40 age spectra for 15415 yielded an age of 3851 +/- 38 Ma with 33-99% of Ar39 release, roughly in agreement with previously reported Ar-Ar ages. For 60015, we obtained an age of 3584 +/- 152 Ma in 23-98% of Ar39 release, also in agreement with previously reported Ar-Ar ages of approximately 3.5 Ga. Highland anorthosites like these are believed by many to be the original crust of the moon, formed by plagioclase floatation atop a magma ocean, however the Ar-Ar ages of 15415 and 60015 are considerably younger than lunar crust formation. By contrast, recently recovered lunar anorthosites such as Dhofar 489, Dhofar 908, and Yamato 86032 yield older Ar-Ar ages, up to 4.35 Ga, much closer to time of formation of the lunar crust. It follows that the Ar-Ar ages of the Apollo samples must have been reset by secondary heating, and that this heating affected highland anorthosites at both the Apollo 15 and Apollo 16 landing sites but did not affect lunar highland meteorites. One obvious consideration is that while the Apollo samples were collected from the near side of the moon, these lunar meteorites are thought to have originated from the lunar far side

Power-law creep and residual stresses in carbopol microgels

NASA Astrophysics Data System (ADS)

Lidon, Pierre; Manneville, Sebastien

We report on the interplay between creep and residual stresses in carbopol microgels. When a constant shear stress σ is applied below the yield stress σc, the strain is shown to increase as a power law of time, γ (t) =γ0 +(t / τ) α , with and exponent α ~= 0 . 38 that is strongly reminiscent of Andrade creep in hard solids. For applied shear stresses lower than some characteristic value of about σc / 10 , the microgels experience a more complex creep behavior that we link to the existence of residual stresses and to weak aging of the system after preshear. The influence of the preshear protocol, of boundary conditions and of microgel concentration on residual stresses is investigated. We discuss our results in light of previous works on colloidal glasses and other soft glassy systems.

First-principles prediction of solar radiation shielding performance for transparent windows of GdB{sub 6}

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

Xiao, Lihua, E-mail: xiaolihua@git.edu.cn; School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083; Guizhou Special Functional Materials 2011 Collaborative Innovation Center, Guizhou Institute of Technology, Guiyang 550003

2016-04-28

The structural, electronic, magnetic, and optical properties of GdB{sub 6} are studied using the first-principles calculations. Calculated values for magnetic and optical properties and lattice constant are found to be consistent with previously reported experimental results. The calculated results show that GdB{sub 6} is a perfect near-infrared absorption/reflectance material that could serve as a solar radiation shielding material for windows with high visible light transmittance, similar to LaB{sub 6}, which is assigned to its plasma oscillation and a collective oscillation (volume plasmon) of carrier electrons. It was found that the magnetic 4f electrons of Gd are not relevant to themore » important optical properties of GdB{sub 6}. These theoretical studies serve as a reference for future studies.« less

Acoustic waveform of continuous bubbling in a non-Newtonian fluid.

PubMed

Vidal, Valérie; Ichihara, Mie; Ripepe, Maurizio; Kurita, Kei

2009-12-01

We study experimentally the acoustic signal associated with a continuous bubble bursting at the free surface of a non-Newtonian fluid. Due to the fluid rheological properties, the bubble shape is elongated, and, when bursting at the free surface, acts as a resonator. For a given fluid concentration, at constant flow rate, repetitive bubble bursting occurs at the surface. We report a modulation pattern of the acoustic waveform through time. Moreover, we point out the existence of a precursor acoustic signal, recorded on the microphone array, previous to each bursting. The time delay between this precursor and the bursting signal is well correlated with the bursting signal frequency content. Their joint modulation through time is driven by the fluid rheology, which strongly depends on the presence of small satellite bubbles trapped in the fluid due to the yield stress.

Fabrication and ferroelectric properties of highly dense lead-free piezoelectric (K0.5Na0.5)NbO3 thick films by aerosol deposition

NASA Astrophysics Data System (ADS)

Ryu, Jungho; Choi, Jong-Jin; Hahn, Byung-Dong; Park, Dong-Soo; Yoon, Woon-Ha; Kim, Ki-Hoon

2007-04-01

Lead-free piezoelectric thick films of (K0.5Na0.5)NbO3 were fabricated by aerosol-deposition method. The thickness of KNN film was 7.1μm and fully dense films were obtained. The dielectric constants ɛ3T/ɛ0 of the as-deposited and annealed films at 1kHz were 116 and 545, respectively, which are higher than any previously reported values for lead-free piezoelectric thin/thick films, either without or with heat treatment. The ferroelectric properties were improved after annealing and the maximum values of Pr=8.1μC/cm3 and Ec=100kV/cm were achieved. These values are markedly superior to those of sintered KNN ceramic counterparts.

Polarization Switching and Light-Enhanced Piezoelectricity in Lead Halide Perovskites.

PubMed

Coll, Mariona; Gomez, Andrés; Mas-Marza, Elena; Almora, Osbel; Garcia-Belmonte, Germà; Campoy-Quiles, Mariano; Bisquert, Juan

2015-04-16

We investigate the ferroelectric properties of photovoltaic methylammonium lead halide CH3NH3PbI3 perovskite using piezoelectric force microscopy (PFM) and macroscopic polarization methods. The electric polarization is clearly observed by amplitude and phase hysteresis loops. However, the polarization loop decreases as the frequency is lowered, persisting for a short time only, in the one second regime, indicating that CH3NH3PbI3 does not exhibit permanent polarization at room temperature. This result is confirmed by macroscopic polarization measurement based on a standard capacitive method. We have observed a strong increase of piezoelectric response under illumination, consistent with the previously reported giant photoinduced dielectric constant at low frequencies. We speculate that an intrinsic charge transfer photoinduced dipole in the perovskite cage may lie at the origin of this effect.

Pitot-probe displacement in a supersonic turbulent boundary layer

NASA Technical Reports Server (NTRS)

Allen, J. M.

1972-01-01

Eight circular pitot probes ranging in size from 2 to 70 percent of the boundary-layer thickness were tested to provide experimental probe displacement results in a two-dimensional turbulent boundary layer at a nominal free-stream Mach number of 2 and unit Reynolds number of 8 million per meter. The displacement obtained in the study was larger than that reported by previous investigators in either an incompressible turbulent boundary layer or a supersonic laminar boundary layer. The large probes indicated distorted Mach number profiles, probably due to separation. When the probes were small enough to cause no appreciable distortion, the displacement was constant over most of the boundary layer. The displacement in the near-wall region decreased to negative displacement in some cases. This near-wall region was found to extend to about one probe diameter from the test surface.

Dependence of sound characteristics on the bowing position in a violin

NASA Astrophysics Data System (ADS)

Roh, YuJi; Kim, Young H.

2014-12-01

A quantitative analysis of violin sounds produced for different bowing positions over the full length of a violin string has been carried out. An automated bowing machine was employed in order to keep the bowing parameters constant. A 3-dimensional profile of the frequency spectrum was introduced in order to characterize the violin's sound. We found that the fundamental frequency did not change for different bowing positions, whereas the frequencies of the higher harmonics were different. Bowing the string at 30 mm from the bridge produced musical sounds. The middle of the string was confirmed to be a dead zone, as reported in previous works. In addition, the quarter position was also found to be a dead zone. Bowing the string 90 mm from the bridge dominantly produces a fundamental frequency of 864 Hz and its harmonics.

Invasive Haemophilus influenzae Serotype f Case Reports in Mazovia Province, Poland.

PubMed

Golebiewska, Anna; Kuch, Alicja; Gawrońska, Agnieszka; Albrecht, Piotr; Skoczyńska, Anna; Radzikowski, Andrzej; Kutylowska, Ewa; Feleszko, Wojciech

2016-02-01

After successful introduction of anti-Haemophilus influenzae (Hi) serotype b vaccination program in Poland, invasive non-b or nontypeable H. influenzae infections have been reported more frequently alike in other countries all over the world. In this paper, we report 2 cases of H. influenzae serotype f (Hif) meningitis with severe clinical presentations which are rarely seen in previously healthy children.The first case is a 6-year-old girl who was admitted to pediatric ward with signs of meningitis. Laboratory tests confirmed bacteremic meningitis caused by Hif. The girl responded very well to administered treatment and recovered without any further complications. No underlying comorbidities were found. The second patient was a 4-year-old boy who, in course of Hif bacteremic meningitis, developed rapid septicemia and, despite aggressive treatment, died within a few hours of hospitalization. The child's past history was unremarkable.By presenting these cases, we would like to remind clinicians that invasive non-b Hi infections can become fatal not only in the group of the youngest children or children with coexisting comorbidities, as most commonly reported in the worldwide literature. At the same time, we want to emphasize the legitimacy of constant monitoring Hi epidemiology in order to take accurate actions if necessary.

Randomized controlled trial in rural Ethiopia to assess a portable water treatment device.

PubMed

Boisson, Sophie; Schmidt, Wolf-Peter; Berhanu, Tsegahiwot; Gezahegn, Henock; Clasen, Thomas

2009-08-01

We conducted a randomized controlled trial to assess the Lifestraw Personal pipe-style water treatment device among a rural population in Ethiopia. A total of 313 households (including 1516 persons) were randomly assigned either to an intervention group in which each householder received a Lifestraw Personal or a control. Households were visited fortnightly over a five-month intervention period and asked to report any episode of diarrhea during the previous week. A random sample of 160 devices was tested each month to assess the presence of thermotolerant coliforms (TTC) and residual iodine in treated water and to measure flow rate under simulated use. Members of the intervention group had 25% fewer weeks with diarrhea than those of the control group (longitudinal prevalence ratio = 0.75; 95% CI 0.60; 0.95). All 718 filtered water samples were free of TTC, were free of detectable iodine disinfectant, and showed a constant flow rate over time. After the five-month intervention period, 34% of participants reported use of device in the preceding week and 13% reported consistent use. While the device was associated with a 25% reduction in longitudinal prevalence of diarrhea, low levels of use suggest that much of this effect is likely to be attributable to reporting bias that is common in open trials with nonobjective outcomes.

Invasive Haemophilus influenzae Serotype f Case Reports in Mazovia Province, Poland

PubMed Central

Golebiewska, Anna; Kuch, Alicja; Gawrońska, Agnieszka; Albrecht, Piotr; Skoczyńska, Anna; Radzikowski, Andrzej; Kutylowska, Ewa; Feleszko, Wojciech

2016-01-01

Abstract After successful introduction of anti-Haemophilus influenzae (Hi) serotype b vaccination program in Poland, invasive non-b or nontypeable H. influenzae infections have been reported more frequently alike in other countries all over the world. In this paper, we report 2 cases of H. influenzae serotype f (Hif) meningitis with severe clinical presentations which are rarely seen in previously healthy children. The first case is a 6-year-old girl who was admitted to pediatric ward with signs of meningitis. Laboratory tests confirmed bacteremic meningitis caused by Hif. The girl responded very well to administered treatment and recovered without any further complications. No underlying comorbidities were found. The second patient was a 4-year-old boy who, in course of Hif bacteremic meningitis, developed rapid septicemia and, despite aggressive treatment, died within a few hours of hospitalization. The child's past history was unremarkable. By presenting these cases, we would like to remind clinicians that invasive non-b Hi infections can become fatal not only in the group of the youngest children or children with coexisting comorbidities, as most commonly reported in the worldwide literature. At the same time, we want to emphasize the legitimacy of constant monitoring Hi epidemiology in order to take accurate actions if necessary. PMID:26844500

High-temperature langatate elastic constants and experimental validation up to 900 degrees C.

PubMed

Davulis, Peter M; da Cunha, Mauricio Pereira

2010-01-01

This paper reports on a set of langatate (LGT) elastic constants extracted from room temperature to 1100 degrees C using resonant ultrasound spectroscopy techniques and an accompanying assessment of these constants at high temperature. The evaluation of the constants employed SAW device measurements from room temperature to 900 degrees C along 6 different LGT wafer orientations. Langatate parallelepipeds and wafers were aligned, cut, ground, and polished, and acoustic wave devices were fabricated at the University of Maine facilities along specific orientations for elastic constant extraction and validation. SAW delay lines were fabricated on LGT wafers prepared at the University of Maine using 100-nm platinumrhodium- zirconia electrodes capable of withstanding temperatures up to 1000 degrees C. The numerical predictions based on the resonant ultrasound spectroscopy high-temperature constants were compared with SAW phase velocity, fractional frequency variation, and temperature coefficients of delay extracted from SAW delay line frequency response measurements. In particular, the difference between measured and predicted fractional frequency variation is less than 2% over the 25 degrees C to 900 degrees C temperature range and within the calculated and measured discrepancies. Multiple temperature-compensated orientations at high temperature were predicted and verified in this paper: 4 of the measured orientations had turnover temperatures (temperature coefficient of delay = 0) between 200 and 420 degrees C, and 2 had turnover temperatures below 100 degrees C. In summary, this work reports on extracted high-temperature elastic constants for LGT up to 1100 degrees C, confirmed the validity of those constants by high-temperature SAW device measurements up to 900 degrees C, and predicted and identified temperature-compensated LGT orientations at high temperature.

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response.

PubMed

Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

2014-01-01

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors.

The structure of binding curves and practical identifiability of equilibrium ligand-binding parameters

PubMed Central

Middendorf, Thomas R.

2017-01-01

A critical but often overlooked question in the study of ligands binding to proteins is whether the parameters obtained from analyzing binding data are practically identifiable (PI), i.e., whether the estimates obtained from fitting models to noisy data are accurate and unique. Here we report a general approach to assess and understand binding parameter identifiability, which provides a toolkit to assist experimentalists in the design of binding studies and in the analysis of binding data. The partial fraction (PF) expansion technique is used to decompose binding curves for proteins with n ligand-binding sites exactly and uniquely into n components, each of which has the form of a one-site binding curve. The association constants of the PF component curves, being the roots of an n-th order polynomial, may be real or complex. We demonstrate a fundamental connection between binding parameter identifiability and the nature of these one-site association constants: all binding parameters are identifiable if the constants are all real and distinct; otherwise, at least some of the parameters are not identifiable. The theory is used to construct identifiability maps from which the practical identifiability of binding parameters for any two-, three-, or four-site binding curve can be assessed. Instructions for extending the method to generate identifiability maps for proteins with more than four binding sites are also given. Further analysis of the identifiability maps leads to the simple rule that the maximum number of structurally identifiable binding parameters (shown in the previous paper to be equal to n) will also be PI only if the binding curve line shape contains n resolved components. PMID:27993951

Infant motivation in dental health: attitude without constant reinforcement.

PubMed

Teixeira Alves, Fabiana Bucholdz; Kuhn, Eunice; Bordin, Danielle; Kozlowski, Vitoldo Antonio; Raggio, Daniela Procida; Fadel, Cristina Berger

2014-01-01

Social factors determine the child's behavior and motivation is an important task in the teaching-learning process. This longitudinal and cross-sectional study aimed to analyze the effectiveness of a motivational activity program for oral hygiene habits formation after motivation and without constant reinforcement. The sample was constituted of 26 children (mean 6 years old) from a Public Kindergarten School in Ponta Grossa, PR, Brazil. Data were collected applying a test-chart, with figures reporting the process of dental health/illness. Some figures were considered positive to dental health (dentist/Cod 1, toothbrush/Cod 3, dentifrice/dental floss/Cod 6, fruits/vegetables/Cod 7 and tooth without caries lesion/Cod 8) and negative on dental health (sweets/Cod 2, bacteria/Cod 4, tooth with caries lesion/Cod 5). The figures presentation occurred in three different stages: First stage - figures were presented to children without previous knowledge; second stage - following the motivational presentation, and third stage - 30 days after the first contact. On the first stage, most children select good for the figures considered harmful to their teeth (Cod 2-88%; Cod 4-77% and Cod 5-65%). On the second stage, there was a lower percentage: 23% (P < 0.0001), 8% (P < 0.0001), and 23% (P = 0.0068) related to the Cod 2, 4, and 5. On the third stage, the results showed again an association with the good choice to these figures considered harmful (Cod 2-85%, Cod 4-65% and Cod 5-54%) similar the results obtained on the first stage. The motivational programs performed without constant reinforcement does not have a positive influence in changing the child's behavior related to a better dental care.

Post-error action control is neurobehaviorally modulated under conditions of constant speeded response

PubMed Central

Soshi, Takahiro; Ando, Kumiko; Noda, Takamasa; Nakazawa, Kanako; Tsumura, Hideki; Okada, Takayuki

2015-01-01

Post-error slowing (PES) is an error recovery strategy that contributes to action control, and occurs after errors in order to prevent future behavioral flaws. Error recovery often malfunctions in clinical populations, but the relationship between behavioral traits and recovery from error is unclear in healthy populations. The present study investigated the relationship between impulsivity and error recovery by simulating a speeded response situation using a Go/No-go paradigm that forced the participants to constantly make accelerated responses prior to stimuli disappearance (stimulus duration: 250 ms). Neural correlates of post-error processing were examined using event-related potentials (ERPs). Impulsivity traits were measured with self-report questionnaires (BIS-11, BIS/BAS). Behavioral results demonstrated that the commission error for No-go trials was 15%, but PES did not take place immediately. Delayed PES was negatively correlated with error rates and impulsivity traits, showing that response slowing was associated with reduced error rates and changed with impulsivity. Response-locked error ERPs were clearly observed for the error trials. Contrary to previous studies, error ERPs were not significantly related to PES. Stimulus-locked N2 was negatively correlated with PES and positively correlated with impulsivity traits at the second post-error Go trial: larger N2 activity was associated with greater PES and less impulsivity. In summary, under constant speeded conditions, error monitoring was dissociated from post-error action control, and PES did not occur quickly. Furthermore, PES and its neural correlate (N2) were modulated by impulsivity traits. These findings suggest that there may be clinical and practical efficacy of maintaining cognitive control of actions during error recovery under common daily environments that frequently evoke impulsive behaviors. PMID:25674058

Reactivity of BrCl, Br₂, BrOCl, Br₂O, and HOBr toward dimethenamid in solutions of bromide + aqueous free chlorine.

PubMed

Sivey, John D; Arey, J Samuel; Tentscher, Peter R; Roberts, A Lynn

2013-02-05

HOBr, formed via oxidation of bromide by free available chlorine (FAC), is frequently assumed to be the sole species responsible for generating brominated disinfection byproducts (DBPs). Our studies reveal that BrCl, Br(2), BrOCl, and Br(2)O can also serve as brominating agents of the herbicide dimethenamid in solutions of bromide to which FAC was added. Conditions affecting bromine speciation (pH, total free bromine concentration ([HOBr](T)), [Cl(-)], and [FAC](o)) were systematically varied, and rates of dimethenamid bromination were measured. Reaction orders in [HOBr](T) ranged from 1.09 (±0.17) to 1.67 (±0.16), reaching a maximum near the pK(a) of HOBr. This complex dependence on [HOBr](T) implicates Br(2)O as an active brominating agent. That bromination rates increased with increasing [Cl(-)], [FAC](o) (at constant [HOBr](T)), and excess bromide (where [Br(-)](o)>[FAC](o)) implicate BrCl, BrOCl, and Br(2), respectively, as brominating agents. As equilibrium constants for the formation of Br(2)O and BrOCl (aq) have not been previously reported, we have calculated these values (and their gas-phase analogues) using benchmark-quality quantum chemical methods [CCSD(T) up to CCSDTQ calculations plus solvation effects]. The results allow us to compute bromine speciation and hence second-order rate constants. Intrinsic brominating reactivity increased in the order: HOBr ≪ Br(2)O < BrOCl ≈ Br(2) < BrCl. Our results indicate that species other than HOBr can influence bromination rates under conditions typical of drinking water and wastewater chlorination.

Chemical weathering in a tropical watershed, Luquillo Mountains, Puerto Rico III: Quartz dissolution rates

USGS Publications Warehouse

Schulz, M.S.; White, A.F.

1999-01-01

The paucity of weathering rates for quartz in the natural environment stems both from the slow rate at which quartz dissolves and the difficulty in differentiating solute Si contributed by quartz from that derived from other silicate minerals. This study, a first effort in quantifying natural rates of quartz dissolution, takes advantage of extremely rapid tropical weathering, simple regolith mineralogy, and detailed information on hydrologic and chemical transport. Quartz abundances and grain sizes are relatively constant with depth in a thick saprolite. Limited quartz dissolution is indicated by solution rounding of primary angularity and by the formation of etch pits. A low correlation of surface area (0.14 and 0.42 m2 g-1) with grain size indicates that internal microfractures and pitting are the principal contributors to total surface area. Pore water silica concentration increases linearly with depth. On a molar basis, between one and three quarters of pore water silica is derived from quartz with the remainder contributed from biotite weathering. Average solute Si remains thermodynamically undersaturated with respect to recently revised estimates of quartz solubility (17-81 ??M). Etch pitting is more abundant on grains in the upper saprolite and is associated with pore waters lower in dissolved silica. Rate constants describing quartz dissolution increase with decreasing depth (from 10-14.5-10-15.1 mol m-2 s-1), which correlate with both greater thermodynamic undersaturation and increasing etch pit densities. Unlike for many aluminosilicates, the calculated natural weathering rates of quartz fall slightly below the rate constants previously reported for experimental studies (10-12.4-10-14.2 mol m-2 s-1). This agreement reflects the structural simplicity of quartz, dilute solutes, and near-hydrologic saturation.

Reinvestigation of the Henry's law constant for hydrogen peroxide with temperature and acidity variation.

PubMed

Huang, Daoming; Chen, Zhongming

2010-01-01

Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx (OH and HO2) radicals and O3 in the atmosphere. Its partitioning between gas and aqueous phases in the atmosphere, usually described by its Henry's law constant (K(H)), significantly influences its role in atmospheric processes. Large discrepancies between the K(H) values reported in previous work, however, have created uncertainty for atmospheric modelers. Based on our newly developed online instrumentation, we have re-determined the temperature and acidity dependence of K(H) for hydrogen peroxide at an air pressure of (0.960 +/- 0.013) atm (1 atm = 1.01325 x 10(5) Pa). The results indicated that the temperature dependence of K(H) for hydrogen peroxide fits to the Van't Hoff equation form, expressed as lnK(H) = a/T - b, and a = -deltaH/R, where K(H) is in M/atm (M is mol/L), T is in degrees Kelvin, R is the ideal gas constant, and deltaH is the standard heat of solution. For acidity dependence, results demonstrated that the K(H) value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level (from pH 7 to pH 1). Combining the dependence of both temperature and acidity, the obtained a and b were 7024 +/- 138 and 11.97 +/- 0.48, respectively, deltaH was (58.40 +/- 1.15) kJ/(K x mol), and the uncertainties represent sigma. Our determined K(H) values for hydrogen peroxide will therefore be of great use in atmospheric models.

Transcultural validation of the Oxford Shoulder Score for the French-speaking population.

PubMed

Tuton, D; Barbe, C; Salmon, J-H; Dramé, M; Nérot, C; Ohl, X

2016-09-01

Patient-reported outcome measures (PROMs) have been gaining in popularity over the last decade. The Oxford Shoulder Score (OSS) is a well-established self-administered questionnaire for shoulder evaluation adapted for the English-speaking population. The aim of the present study was to develop a translation and a transcultural adaptation of the OSS and to assess its validity in native French-speaker patients with shoulder pain. The translation process was carried out following a translation/back-translation methodology by two translators. All patients completed the French OSS, the Subjective Shoulder Value (SSV), and the Constant score. Internal consistency was tested using Cronbach's α coefficient. Validity was assessed by calculating the Pearson correlation coefficient between the OSS and the Constant score and the SSV. One hundred forty-four patients suffering from degenerative or inflammatory diseases of the shoulder were included in this study. The average time required to complete the French OSS was 2min and 45s. Seventy patients were asked to complete the questionnaire twice (test/retest reliability). Internal consistency was high with Cronbach's α coefficient=0.93. The intraclass correlation coefficient was 0.91 (95% CI: 0.88-0.94) for test/retest reliability. The French OSS score was significantly correlated with the Constant-Murley score (r=0.73 and P<0.0001) and with the SSV (r=0.68 and P<0.0001). The present study shows that the French version of the OSS is reliable, valid, and reproducible. The sensitivity to change now needs to be evaluated. This score was adapted to the French-speaking population for the self-assessment of patients with degenerative or inflammatory disorders of the shoulder. Level 1, Test of previously developed criteria, diagnostic test study. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Kinetics of the oxidation of cylindrospermopsin and anatoxin-a with chlorine, monochloramine and permanganate.

PubMed

Rodríguez, Eva; Sordo, Ana; Metcalf, James S; Acero, Juan L

2007-05-01

Cyanobacteria produce toxins that may contaminate drinking water sources. Among others, the presence of the alkaloid toxins cylindrospermopsin (CYN) and anatoxin-a (ANTX) constitutes a considerable threat to human health due to the acute and chronic toxicity of these compounds. In the present study, not previously reported second-order rate constants for the reactions of CYN and ANTX with chlorine and monochloramine and of CYN with potassium permanganate were determined and the influence of pH and temperature was established for the most reactive cases. It was found that the reactivity of CYN with chlorine presents a maximum at pH 7 (rate constant of 1265 M(-1)s(-1)). However, the oxidation of CYN with chloramine and permanganate are rather slow processes, with rate constants <1 M(-1)s(-1). The first chlorination product of CYN was found to be 5-chloro-CYN (5-Cl-CYN), which reacts with chlorine 10-20 times slower than the parent compound. The reactivity of ANTX with chlorine and chloramines is also very low (k<1M(-1)s(-1)). The elimination of CYN and ANTX in surface water was also investigated. A chlorine dose of 1.5 mg l(-1) was enough to oxidize CYN almost completely. However, 3 mg l(-1) of chlorine was able to remove only 8% of ANTX, leading to a total formation of trihalomethanes (TTHM) at a concentration of 150 microg l(-1). Therefore, chlorination is a feasible option for CYN degradation during oxidation and disinfection processes but not for ANTX removal. The permanganate dose required for CYN oxidation is very high and not applicable in waterworks.

Bond-strength inversion in (In,Ga)As semiconductor alloys

NASA Astrophysics Data System (ADS)

Eckner, Stefanie; Ritter, Konrad; Schöppe, Philipp; Haubold, Erik; Eckner, Erich; Rensberg, Jura; Röder, Robert; Ridgway, Mark C.; Schnohr, Claudia S.

2018-05-01

The atomic-scale structure and vibrational properties of semiconductor alloys are determined by the energy required for stretching and bending the individual bonds. Using temperature-dependent extended x-ray absorption fine-structure spectroscopy, we have determined the element-specific In-As and Ga-As effective bond-stretching force constants in (In,Ga)As as a function of the alloy composition. The results reveal a striking inversion of the bond strength where the originally stiffer bond in the parent materials becomes the softer bond in the alloy and vice versa. Our findings clearly demonstrate that changes of both the individual bond length and the surrounding matrix affect the bond-stretching force constants. We thus show that the previously used common assumptions about the element-specific force constants in semiconductor alloys do not reproduce the composition dependence determined experimentally for (In,Ga)As.

Thermodynamic and related properties of parahydrogen from the triple point to 300 K at pressures to 1000 bar

NASA Technical Reports Server (NTRS)

Weber, L. A.

1975-01-01

Compressibility measurements and thermodynamic properties data for parahydrogen were extended to higher temperatures and pressures. Results of an experimental program are presented in the form of new pressure, volume and temperature data in the temperature range 23 to 300 K at pressures up to 800 bar. Also given are tables of thermodynamic properties on isobars to 1000 bar including density, internal energy, enthalpy, entropy, specific heats at constant volume and constant pressure, velocity of sound, and surface derivatives. The accuracy of the data is discussed and comparisons are made with previous data.

High-pressure study of layered nitride superconductors

NASA Astrophysics Data System (ADS)

Taguchi, Y.; Hisakabe, M.; Ohishi, Y.; Yamanaka, S.; Iwasa, Y.

2004-09-01

Pressure dependence of critical temperature, lattice constant, and phonon frequency has been investigated for layered nitride superconductors, ZrNCl0.7 and Li0.5(THF)yHfNCl . The analysis of the data in terms of MacMillan’s theory indicated that the relevant phonon frequencies are low ( ≈50 and 100cm-1 , respectively), and that the electron-phonon coupling constant λ is larger than 3 in both compounds in sharp contrast with previous experimental and theoretical results. This result may suggest a possibility that other bosonic excitation than phonon additionally contributes to the pairing interaction in these materials.

High pressure study on layered nitride superconductors

NASA Astrophysics Data System (ADS)

Taguchi, Y.; Hisakabe, M.; Ohishi, Y.; Yamanaka, S.; Iwasa, Y.

2004-03-01

Pressure dependence of critical temperature, lattice constant, and phonon frequency has been investigated for layered nitride superconductors, Li_0.5(THF)_yHfNCl and ZrNCl_0.7. The data have been analyzed in terms of MacMillan's theory, and electron-phonon coupling constant λ (=1.3), Coulomb pseudopotential μ^* (=0.31), and relevant phonon frequency (=630 cm-1) have been extracted. The obtained value of λ exceeds 1 in contrast with previous experimental and theoretical results. The present result indicates that, if the superconductivity is within a MacMillan scheme, it is mediated by high frequency phonons in a strong coupling regime.

Three-Wire Thermocouple: Frequency Response in Constant Flow

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1995-01-01

Theory and experimental measurements are compared with a novel three-wire thermocouple. Signals from three wires of unequal diameters are recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three-wire thermocouple requires no compensation for omega less than or equal to 5(omega(sub 1)), where omega(sub 1) is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two-wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter.

Three-wire Thermocouple: Frequency Response in Constant Flow

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1995-01-01

Theory and experimental measurements are compared with a novel three-wire thermocouple. Signals from three wires of unequal diameters arc recorded from the thermocouple suspended in constant flow with a periodic temperature fluctuation. It is demonstrated that the reconstructed signal from the three-wire thermocouple requires no compensation for omega less than or equal to 5(sub omega1), where omega, is the natural frequency of the smaller wire. The latter result represents a significant improvement compared to previous work with two-wire thermocouples. A correction factor has also been derived to account for wires of arbitrary diameter.

Rate constant for the reaction NH2 + NO from 216 to 480 K

NASA Technical Reports Server (NTRS)

Stief, L. J.; Brobst, W. D.; Nava, D. F.; Borkowski, R. P.; Michael, J. V.

1982-01-01

The absolute rate constant was measured by the technique of flash photolysis-laser induced fluorescence (FP-LIF). NH2 radicals were produced by the flash photolysis of ammonia and the fluorescent NH2 photons were measured by multiscaling techniques. At each temperature, the results were independent of variations in total pressure, and flash intensity. The results are compared with previous determinations using the techniques of mass spectrometry, absorption spectroscopy, laser absorption spectroscopy, and laser induced fluorescence. The implications of the results are discussed with regard to combustion, post combustion, and atmospheric chemistry. The results are also discussed theoretically.

Measurement of Newton's constant using a torsion balance with angular acceleration feedback.

PubMed

Gundlach, J H; Merkowitz, S M

2000-10-02

We measured Newton's gravitational constant G using a new torsion balance method. Our technique greatly reduces several sources of uncertainty compared to previous measurements: (1) It is insensitive to anelastic torsion fiber properties; (2) a flat plate pendulum minimizes the sensitivity due to the pendulum density distribution; (3) continuous attractor rotation reduces background noise. We obtain G = (6.674215+/-0.000092) x 10(-11) m3 kg(-1) s(-2); the Earth's mass is, therefore, M = (5.972245+/-0.000082) x 10(24) kg and the Sun's mass is M = (1.988435+/-0.000027) x 10(30) kg.

[Mechanism of the constant representation of the position of a sound signal source by the cricket cercal system neurons].

PubMed

Rozhkova, G I; Polishcuk, N A

1976-01-01

Previously it has been shown that some abdominal giant neurones of the cricket have constant preffered directions of sound stimulation in relation not to the cerci (the organs bearing sound receptors) but to the insect body (fig. 1) [1]. Now it is found that the independence of directional sensitivity of giant neurones on the cerci position disappears after cutting all structures connecting the cerci to the body (except cercal nerves) (fig 2). Therefore the constancy of directional sensitivity of the giant nerones is provided by proprioceptive signals about cerci position.

Icosahedral quasicrystal Al71Pd21Mn08 and its ξ' approximant: Linear expansivity, specific heat, magnetic susceptibility, electrical resistivity, and elastic constants

NASA Astrophysics Data System (ADS)

Swenson, C. A.; Fisher, I. R.; Anderson, N. E.; Canfield, P. C.; Migliori, A.

2002-05-01

Linear thermal expansivity (α, 1-300 K), heat capacity (Cp, 1-108 K), magnetic susceptibility (χ, 1-300 K), and electrical resistivity (ρ, 1-300 K) measurements are reported for a single-grain i-Al71Pd21Mn08 quasicrystal and its Al72Pd25Mn03 approximant, and 300 K elastic constants for the quasicrystal. The approximant α (αAp) and Cp (CpAp) data show ``metallic'' behavior, while the previously reported onset of a transition to a spin-glass state (Tf<1.8 K) dominates αQ and CpQ below 11 K. CpAp and CpQ superimpose above 16 K when plotted vs T/Θ0 using the experimental Θ0Ap=455(3) K and an adjusted Θ0ApQ=480(4) K. The 300 K elastic constants extrapolated to T=0 give Θel0Q=505(1) K, suggesting that the normalization is valid only above 16 K. The lattice contribution to CpAp (and, indirectly, CpQ) shows strong (unique) deviations from Debye-like behavior (+3% at 0.84 K for the CpAp data fit). The various Grüneisen parameters (Γ) that are calculated from these data all are positive and normal in magnitude except for a large limiting approximant lattice value, Γlat0Ap=11.3, which may be related to the large dispersion effects in Cp. For the approximant, the combination of anisotropic and large resistivities, a small diamagnetic susceptibility, and a ``large'' linear (electronic) contribution to CpAp (γAp=0.794 mJ/mol K2) suggests the existence of a pseudogap in the electronic density of states. The unusually large, highly volume dependent, dispersion at low temperatures for the quasicrystal and its approximant are not consistent with inelastic neutron scattering and other data, and raise questions about the role of phonons in quasicrystals. The present 300 K resistivities can be used with a published correlation to estimate γQ~0.25 mJ/mol K2.

Processing of Al2O3/SrTiO3/PDMS Composites With Low Dielectric Loss

NASA Astrophysics Data System (ADS)

Yao, J. L.; Guo, M. J.; Qi, Y. B.; Zhu, H. X.; Yi, R. Y.; Gao, L.

2018-05-01

Polydimethylsiloxane (PDMS) is widely used in the electrical and electronic industries due to its excellent electrical insulation and biocompatible characteristics. However, the dielectric constant of pure PDMS is very low which restricts its applications. Herein, we report a series of PDMS/Al2O3/strontium titanate (ST) composites with high dielectric constant and low loss prepared by a simple experimental method. The composites exhibit high dielectric constant (relative dielectric constant is 4) after the composites are coated with insulated Al2O3 particles, and the dielectric constant gets further improved for composites with ST particles (dielectric constant reaches 15.5); a lower dielectric loss (tanδ= 0.05) is also found at the same time which makes co-filler composites suitable for electrical insulation products, and makes the experimental method more interesting in modern teaching.

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

Shyam, Amit; Lara-Curzio, Edgar

This paper reports on the langatate (LGT) elastic constants measured from room temperature (25 C) to 1100 C using resonant ultrasound spectroscopy (RUS). The constants were extracted by fitting the resonant peaks with those calculated by Lagrangian mechanics at each temperature where the RUS measurements were taken. In addition, the RUS technique was used to extract the piezoelectric constants in the 25 C to 120 C temperature range. This work also publishes a set of temperature coefficients for the elastic constants up to 1100 C. For the measurements, six parallelepiped LGT samples were aligned, cut, ground, and polished at themore » University of Maine. The samples were aligned to two different crystal orientations, to increase the reliability of the constant fitting. The extraction of LGT elastic constants up to 1100 C presented in this paper represents a critical step towards the design and fabrication of LGT acoustic wave devices for high temperature and harsh environment applications.« less

Contribution of irregular semicircular canal afferents to the horizontal vestibuloocular response during constant velocity rotation

NASA Technical Reports Server (NTRS)

Angelaki, D. E.; Perachio, A. A.

1993-01-01

1. The effects of constant anodal currents (100 microA) delivered bilaterally to both labyrinths on the horizontal vestibuloocular response (VOR) were studied in squirrel monkeys during steps of angular velocity in the dark. We report that bilateral anodal currents decreased eye velocity approximately 30-50% during the period of galvanic stimulation without a change in the time constant of VOR. The decrease in eye velocity, present during steps of angular velocity, was not observed during sinusoidal head rotation at 0.2, 0.5, and 1 Hz. The results suggest that responses from irregular vestibular afferents influence VOR amplitude during constant velocity rotation.

Hyperfine structure investigations for the odd-parity configuration system in atomic holmium

NASA Astrophysics Data System (ADS)

Stefanska, D.; Furmann, B.

2018-02-01

In this work new experimental results of the hyperfine structure (hfs) in the holmium atom are reported, concerning the odd-parity level system. Investigations were performed by the method of laser induced fluorescence in a hollow cathode discharge lamp on 97 spectral lines in the visible part of the spectrum. Hyperfine structure constants: magnetic dipole - A and electric quadrupole - B for 40 levels were determined for the first time; for another 21 levels the hfs constants available in the literature were remeasured. Results for the A constants can be viewed as fully reliable; for B constants further possibilities of improving the accuracy are considered.

New techniques for positron emission tomography in the study of human neurological disorders: Progress report, 15 June 1992--31 October 1992

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

Not Available

1992-01-01

During the past six months, we have continued work on the fronts of kinetic modeling of radioligands for studying neurotransmitter/receptor systems, iterative reconstruction techniques, and methodology for PET cerebral blood flow activation studies. Initial human PET studies have been performed and analyzed with many different kinetic model formulations to determine the quantitative potential of the neuronwsmitter/receptor ligand, ({sup 11}C)N-methyl piperidyl benzilate (NMPB), a muscarinic cholinergic antagonist. In addition, initial human studies using ({sup 11}C)tetrabenazine (TBZ), a marker for monoantine nerve terminal density. Results of the NWB studies have indicated that this new agent yields better estimates of receptor density thanmore » previous muscarinic ligands developed at our facility, ({sup 11}C)-TRB and ({sup 11}C)scopolamine. TRB and scopolamine have previously been shown to be only partially successful ligands due to sub-optimal values of the individual rate constants, causing varying degrees of flow limitation. This is found to be much less of a problem for NMPB due to the 2.0--2.5 fold increase in ligand transport observed in the human studies ({approximately}60% first pass extraction). A 2-parameter 2-compartment simplification had previously been implemented for the benzodiazepine ligand, (C-11)FMZ, and a similar model appears to be suitable for TBZ based on the preliminary human data.« less

New techniques for positron emission tomography in the study of human neurological disorders: Progress report, 15 June 1992--31 October 1992

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

Not Available

1992-10-01

During the past six months, we have continued work on the fronts of kinetic modeling of radioligands for studying neurotransmitter/receptor systems, iterative reconstruction techniques, and methodology for PET cerebral blood flow activation studies. Initial human PET studies have been performed and analyzed with many different kinetic model formulations to determine the quantitative potential of the neuronwsmitter/receptor ligand, [{sup 11}C]N-methyl piperidyl benzilate (NMPB), a muscarinic cholinergic antagonist. In addition, initial human studies using [{sup 11}C]tetrabenazine (TBZ), a marker for monoantine nerve terminal density. Results of the NWB studies have indicated that this new agent yields better estimates of receptor density thanmore » previous muscarinic ligands developed at our facility, [{sup 11}C]-TRB and [{sup 11}C]scopolamine. TRB and scopolamine have previously been shown to be only partially successful ligands due to sub-optimal values of the individual rate constants, causing varying degrees of flow limitation. This is found to be much less of a problem for NMPB due to the 2.0--2.5 fold increase in ligand transport observed in the human studies ({approximately}60% first pass extraction). A 2-parameter 2-compartment simplification had previously been implemented for the benzodiazepine ligand, [C-11]FMZ, and a similar model appears to be suitable for TBZ based on the preliminary human data.« less

The constant region affects antigen binding of antibodies to DNA by altering secondary structure.

PubMed

Xia, Yumin; Janda, Alena; Eryilmaz, Ertan; Casadevall, Arturo; Putterman, Chaim

2013-11-01

We previously demonstrated an important role of the constant region in the pathogenicity of anti-DNA antibodies. To determine the mechanisms by which the constant region affects autoantibody binding, a panel of isotype-switch variants (IgG1, IgG2a, IgG2b) was generated from the murine PL9-11 IgG3 autoantibody. The affinity of the PL9-11 antibody panel for histone was measured by surface plasmon resonance (SPR). Tryptophan fluorescence was used to determine wavelength shifts of the antibody panel upon binding to DNA and histone. Finally, circular dichroism spectroscopy was used to measure changes in secondary structure. SPR analysis revealed significant differences in histone binding affinity between members of the PL9-11 panel. The wavelength shifts of tryptophan fluorescence emission were found to be dependent on the antibody isotype, while circular dichroism analysis determined that changes in antibody secondary structure content differed between isotypes upon antigen binding. Thus, the antigen binding affinity is dependent on the particular constant region expressed. Moreover, the effects of antibody binding to antigen were also constant region dependent. Alteration of secondary structures influenced by constant regions may explain differences in fine specificity of anti-DNA antibodies between antibodies with similar variable regions, as well as cross-reactivity of anti-DNA antibodies with non-DNA antigens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Stepwise formation of H3O(+)(H2O)n in an ion drift tube: Empirical effective temperature of association/dissociation reaction equilibrium in an electric field.

PubMed

Nakai, Yoichi; Hidaka, Hiroshi; Watanabe, Naoki; Kojima, Takao M

2016-06-14

We measured equilibrium constants for H3O(+)(H2O)n-1 + H2O↔H3O(+)(H2O)n (n = 4-9) reactions taking place in an ion drift tube with various applied electric fields at gas temperatures of 238-330 K. The zero-field reaction equilibrium constants were determined by extrapolation of those obtained at non-zero electric fields. From the zero-field reaction equilibrium constants, the standard enthalpy and entropy changes, ΔHn,n-1 (0) and ΔSn,n-1 (0), of stepwise association for n = 4-8 were derived and were in reasonable agreement with those measured in previous studies. We also examined the electric field dependence of the reaction equilibrium constants at non-zero electric fields for n = 4-8. An effective temperature for the reaction equilibrium constants at non-zero electric field was empirically obtained using a parameter describing the electric field dependence of the reaction equilibrium constants. Furthermore, the size dependence of the parameter was thought to reflect the evolution of the hydrogen-bond structure of H3O(+)(H2O)n with the cluster size. The reflection of structural information in the electric field dependence of the reaction equilibria is particularly noteworthy.

The effects of MgADP on cross-bridge kinetics: a laser flash photolysis study of guinea-pig smooth muscle.

PubMed Central

Nishiye, E; Somlyo, A V; Török, K; Somlyo, A P

1993-01-01

1. The effects of MgADP on cross-bridge kinetics were investigated using laser flash photolysis of caged ATP (P3-1(2-nitrophenyl) ethyladenosine 5'-triphosphate), in guinea-pig portal vein smooth muscle permeabilized with Staphylococcus aureus alpha-toxin. Isometric tension and in-phase stiffness transitions from rigor state were monitored upon photolysis of caged ATP. The estimated concentration of ATP released from caged ATP by high-pressure liquid chromatography (HPLC) was 1.3 mM. 2. The time course of relaxation initiated by photolysis of caged ATP in the absence of Ca2+ was well fitted during the initial 200 ms by two exponential functions with time constants of, respectively, tau 1 = 34 ms and tau 2 = 1.2 s and relative amplitudes of 0.14 and 0.86. Multiple exponential functions were needed to fit longer intervals; the half-time of the overall relaxation was 0.8 s. The second order rate constant for cross-bridge detachment by ATP, estimated from the rate of initial relaxation, was 0.4-2.3 x 10(4) M-1 s-1. 3. MgADP dose dependently reduced both the relative amplitude of the first component and the rate constant of the second component of relaxation. Conversely, treatment of muscles with apyrase, to deplete endogenous ADP, increased the relative amplitude of the first component. In the presence of MgADP, in-phase stiffness decreased during force maintenance, suggesting that the force per cross-bridge increased. The apparent dissociation constant (Kd) of MgADP for the cross-bridge binding site, estimated from its concentration-dependent effect on the relative amplitude of the first component, was 1.3 microM. This affinity is much higher than the previously reported values (50-300 microM for smooth muscle; 18-400 microM for skeletal muscle; 7-10 microM for cardiac muscle). It is possible that the high affinity reflects the properties of a state generated during the co-operative reattachment cycle, rather than that of the rigor bridge. 4. The rate constant of MgADP release from cross-bridges, estimated from its concentration-dependent effect on the rate constant of the second (tau 2) component, was 0.35-7.7 s-1. To the extent that reattachment of cross-bridges could slow relaxation even during the initial 200 ms, this rate constant may be an underestimate. 5. Inorganic phosphate (Pi, 30 mM) did not affect the rate of relaxation during the initial approximately 50 ms, but accelerated the slower phase of relaxation, consistent with a cyclic cross-bridge model in which Pi increases the proportion of cross-bridges in detached ('weakly bound') states.(ABSTRACT TRUNCATED AT 400 WORDS) Images Fig. 1 PMID:8487195