Switchable solvents and methods of use thereof

DOEpatents

Jessop, Philip G; Eckert, Charles A; Liotta, Charles L; Heldebrant, David J

2014-04-29

A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO.sub.2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

Bench-top soldering aid for PC boards

NASA Technical Reports Server (NTRS)

Manton, N. R.; Schroff, R. A.

1978-01-01

Multiple-board rack allows technician to insert components into several boards, flip them all in single motion, and then systematically solder leads on reverse side. Two adjustable crossbars allow boards of any size up to 10 by 24 inches. Operator can rotate racks and adjust angle of boards from standing or sitting position.

Reverse Polarity Magnetized Melt Rocks from the Cretaceous/Tertiary Chicxulub Structure, Yucatan Peninsula, Mexico

NASA Technical Reports Server (NTRS)

Urrutia-Fucugauchi, J.; Marin, Luis; Sharpton, Virgil L.

1994-01-01

We report paleomagnetic results for core samples of the breccia and andesitic rocks recovered from the Yucatan-6 Petrolcos Mexicanos exploratory well within the Chicxulub structure (about 60 km SSW from its center), northern Yucatan, Mexico. A previous study has shown that the rocks studied contain high iridium levels and shocked breccia clasts and an Ar/Ar date of 65.2 +/- 0.4 Ma. Andesitic rocks are characterized by stable single-component magnetizations with a mean inclination of -42.6 deg +/- 2.4 deg. Breccias present a complex paleomagnetic record characterized by multivectorial magnetizations with widely different initial NRM inclinations. However, after alternating field demagnetization, well defined characteristic components with upward inclinations are defined. IRM acquisition experiments, comparison of IRM and NRM coercivity spectra and the single component magnetization of the andesitic rocks indicate the occurrence of iron-rich titanomagnetites of single or pseudo-single domain states as the dominant magnetic carriers. Mean inclinations from the andesitic rocks and most of the breccia samples give a mean inclination of about -40 deg to -45 deg, indicating a reverse polarity for the characteristic magnetization that is consistent with geomagnetic chron 29R, which spans the Cretaceous/Tertiary (K/T) boundary. The inclination is also consistent with the expected value (and corresponding paleolatitude) for the site estimated from the reference polar wander curve for North America. We suggest that the characteristic magnetizations for the andesitic and breccia rocks are the result of shock heating at the time of formation of the impact structure and that the age, polarity and pateolatitude are consistent with a time at the K/T boundary.

Large amplitude Fourier transformed ac voltammetry at a rotating disc electrode: a versatile technique for covering Levich and flow rate insensitive regimes in a single experiment.

PubMed

Bano, Kiran; Kennedy, Gareth F; Zhang, Jie; Bond, Alan M

2012-04-14

The theory for large amplitude Fourier transformed ac voltammetry at a rotating disc electrode is described. Resolution of time domain data into dc and ac harmonic components reveals that the mass transport for the dc component is controlled by convective-diffusion, while the background free higher order harmonic components are flow rate insensitive and mainly governed by linear diffusion. Thus, remarkable versatility is available; Levich behaviour of the dc component limiting current provides diffusion coefficient values and access to higher harmonics allows fast electrode kinetics to be probed. Two series of experiments (dc and ac voltammetry) have been required to extract these parameters; here large amplitude ac voltammetry with RDE methodology is used to demonstrate that kinetics and diffusion coefficient information can be extracted from a single experiment. To demonstrate the power of this approach, theoretical and experimental comparisons of data obtained for the reversible [Ru(NH(3))(6)](3+/2+) and quasi-reversible [Fe(CN)(6)](3-/4-) electron transfer processes are presented over a wide range of electrode rotation rates and with different concentrations and electrode materials. Excellent agreement of experimental and simulated data is achieved, which allows parameters such as electron transfer rate, diffusion coefficient, uncompensated resistance and others to be determined using a strategically applied approach that takes into account the different levels of sensitivity of each parameter to the dc or the ac harmonic.

Reversible and non-reversible changes in nanostructured Si in humid atmosphere

NASA Astrophysics Data System (ADS)

Zhigalov, V.; Pyatilova, O.; Timoshenkov, S.; Gavrilov, S.

2014-12-01

Atmosphere water influence in the nanostructured silicon (NSS) was investigated by IR-spectroscopy and electron work function measurement. Long-term non-reversible dynamics of IR-spectra was found as a result of 100% humidity influence on the nanostructured silicon. It was indicated that air humidity affects on the work function. Dynamics of the electron work function consists of reversible and non-reversible components. Reversible component appears as strong anti-correlation between work function and humidity. Work function change of NSS is about 0.4 eV while the humidity changes between 0% and 100%. Reversible component can be explained by physical sorption of water molecules on the surface. Non-reversible component manifests as long-term decreasing trend of work function in humid atmosphere. Transition curve during abruptly humidity changes alters its shape. Non-reversible component can be explained by chemisorption of water.

Intermediate-type vancomycin resistance (VISA) in genetically-distinct Staphylococcus aureus isolates is linked to specific, reversible metabolic alterations.

PubMed

Alexander, Elizabeth L; Gardete, Susana; Bar, Haim Y; Wells, Martin T; Tomasz, Alexander; Rhee, Kyu Y

2014-01-01

Intermediate (VISA-type) vancomycin resistance in Staphylococcus aureus has been associated with a range of physiologic and genetic alterations. Previous work described the emergence of VISA-type resistance in two clonally-distinct series of isolates. In both series (the first belonging to MRSA clone ST8-USA300, and the second to ST5-USA100), resistance was conferred by a single mutation in yvqF (a negative regulator of the vraSR two-component system associated with vancomycin resistance). In the USA300 series, resistance was reversed by a secondary mutation in vraSR. In this study, we combined systems-level metabolomic profiling with statistical modeling techniques to discover specific, reversible metabolic alterations associated with the VISA phenotype.

The effects of monoamine oxidase inhibitors on the ejaculatory response induced by 5-methoxy-N,N-dimethyltryptamine in the rat.

PubMed Central

Rényi, L.

1986-01-01

The ejaculatory response and other components of the 5-hydroxytryptamine (5-HT) behavioural syndrome induced by 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) (3 mg kg-1, i.p.) were studied following single and repeated treatment of rats with eight different monoamine oxidase (MAO) inhibitors. Single and repeated treatment with the 5-HT agonist 5-MeODMT, and with low doses of the potent releaser of 5-HT, p-chloroamphetamine (PCA) were also included in the study. Repeated but not single treatment with 5-MeODMT reduced strongly but reversibly the ejaculatory response and the behavioural responses. Repeated but not single treatment with the nonselective and irreversible MAO inhibitors nialamide and pargyline reduced markedly the ejaculatory response but only slightly the 5-HT behavioural responses. Repeated treatment with the irreversible MAO-B inhibitor (-)-deprenyl, with the irreversible MAO-A inhibitor, clorgyline, with the reversible MAO-A inhibitor moclobemide, and with low doses of PCA did not affect either of the responses. Repeated but not single combined treatment with clorgyline plus PCA caused an almost complete blockade of all the four responses. The selective and reversible MAO-A inhibitors (as well as 5-HT releasers) amiflamine, alpha-ethyltryptamine, and alpha-methyltryptamine reduced markedly the ejaculatory response after both single and repeated treatments. The behavioural responses were blocked only after repeated treatment. It is concluded that single and repeated treatments of rats with different MAO inhibitors do not produce a common alteration in 5-HT2 receptor functions. Repeated treatment with 5-MeODMT caused a blockade of 75-95% of the ejaculatory response and 5-HT behavioural responses.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3091132

Functionality of In vitro Reconstituted Group II Intron RmInt1-Derived Ribonucleoprotein Particles.

PubMed

Molina-Sánchez, Maria D; García-Rodríguez, Fernando M; Toro, Nicolás

2016-01-01

The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms. The Sinorhizobium meliloti group II intron RmInt1 is an efficient mobile retroelement, the dispersal of which appears to be linked to transient single-stranded DNA during replication. The RmInt1IEP lacks the endonuclease domain (En) and cannot cut the bottom strand to generate the 3' end to initiate reverse transcription. We used an Escherichia coli expression system to produce soluble and active RmInt1 IEP and reconstituted RNPs with purified components in vitro . The RNPs generated were functional and reverse-spliced into a single-stranded DNA target. This work constitutes the starting point for the use of group II introns lacking DNA endonuclease domain-derived RNPs for highly specific gene targeting methods.

Functionality of In vitro Reconstituted Group II Intron RmInt1-Derived Ribonucleoprotein Particles

PubMed Central

Molina-Sánchez, Maria D.; García-Rodríguez, Fernando M.; Toro, Nicolás

2016-01-01

The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms. The Sinorhizobium meliloti group II intron RmInt1 is an efficient mobile retroelement, the dispersal of which appears to be linked to transient single-stranded DNA during replication. The RmInt1IEP lacks the endonuclease domain (En) and cannot cut the bottom strand to generate the 3′ end to initiate reverse transcription. We used an Escherichia coli expression system to produce soluble and active RmInt1 IEP and reconstituted RNPs with purified components in vitro. The RNPs generated were functional and reverse-spliced into a single-stranded DNA target. This work constitutes the starting point for the use of group II introns lacking DNA endonuclease domain-derived RNPs for highly specific gene targeting methods. PMID:27730127

Reversible Aptamer-Au Plasmon Rulers for Secreted Single Molecules

DOE PAGES

Lee, Somin Eunice; Chen, Qian; Bhat, Ramray; ...

2015-06-03

Plasmon rulers, consisting of pairs of gold nanoparticles, allow single-molecule analysis without photobleaching or blinking; however, current plasmon rulers are irreversible, restricting detection to only single events. Here, we present a reversible plasmon ruler, comprised of coupled gold nanoparticles linked by a single aptamer, capable of binding individual secreted molecules with high specificity. We show that the binding of target secreted molecules to the reversible plasmon ruler is characterized by single-molecule sensitivity, high specificity, and reversibility. Lastly, such reversible plasmon rulers should enable dynamic and adaptive live-cell measurement of secreted single molecules in their local microenvironment.

Study of the magnetic interaction in nanocrystalline Pr-Fe-Co-Nb-B permanent magnets

NASA Astrophysics Data System (ADS)

Dospial, M.; Plusa, D.; Ślusarek, B.

2012-03-01

The magnetic properties of an isotropic, epoxy resin bonded magnets made from Pr-Fe-Co-Nb-B powder were investigated. The magnetization reversal process and magnetic parameters were examined by measurements of the initial magnetization curve, major and minor hysteresis loops and sets of recoil curves. From the initial magnetization curve and the field dependencies of the reversible and irreversible magnetization components derived from the recoil loops it was found that the magnetization reversal process is the combination of the nucleation of reversed domains and pinning of domain walls at the grain boundaries and the reversible rotation of magnetization vector in single domain grains. The interactions between grains were studied by means of δM plots. The nonlinear behavior of δM curve approve that the short range intergrain exchange coupling interactions are dominant in a field up to the sample coercivity. The interaction domains and fine magnetic structure were revealed as the evidence of exchange coupling between soft α-Fe and hard magnetic Nd2Fe14B grains.

Study of reversible magnetization in FeCoNi alloy nanowires with different diameters by first order reversal curve (FORC) diagrams

NASA Astrophysics Data System (ADS)

Samanifar, S.; Kashi, M. Almasi; Ramazani, A.

2018-05-01

Magnetic nanowires electrodeposited into solid templates are of high interest due to their tunable properties which are required for magnetic recording media and spintronic devices. Here, highly ordered arrays of FeCoNi NWs with varied diameters (between 60 and 150 nm) were fabricated into nanopores of hard-anodized aluminum oxide templates using pulsed ac electrodeposition technique. X-ray diffraction patterns indicated the formation of FeCoNi NWs with fcc FeNi and bcc FeCo alloy phases, being highly textured along the bcc [110] direction. Magnetic properties were studied by hysteresis loop measurements at room temperature and they showed reductions in coercivity and squareness values by increasing diameter. First-order reversal curve measurements revealed that, with increasing diameter from 60 to 150 nm, besides a transition from a single domain (SD) state to a pseudo SD state, an increase in the reversible magnetization component of the NWs from 11% to 24% occurred.

The optical rebrightening of GRB100814A: an interplay of forward and reverse shocks?

NASA Astrophysics Data System (ADS)

De Pasquale, Massimiliano; Kuin, N. P. M.; Oates, S.; Schulze, S.; Cano, Z.; Guidorzi, C.; Beardmore, A.; Evans, P. A.; Uhm, Z. L.; Zhang, B.; Page, M.; Kobayashi, S.; Castro-Tirado, A.; Gorosabel, J.; Sakamoto, T.; Fatkhullin, T.; Pandey, S. B.; Im, M.; Chandra, P.; Frail, D.; Gao, H.; Kopač, D.; Jeon, Y.; Akerlof, C.; Huang, K. Y.; Pak, S.; Park, W.-K.; Gomboc, A.; Melandri, A.; Zane, S.; Mundell, C. G.; Saxton, C. J.; Holland, S. T.; Virgili, F.; Urata, Y.; Steele, I.; Bersier, D.; Tanvir, N.; Sokolov, V. V.; Moskvitin, A. S.

2015-05-01

We present a wide data set of gamma-ray, X-ray, UV/Opt/IR (UVOIR), and radio observations of the Swift GRB100814A. At the end of the slow decline phase of the X-ray and optical afterglow, this burst shows a sudden and prominent rebrightening in the optical band only, followed by a fast decay in both bands. The optical rebrightening also shows chromatic evolution. Such a puzzling behaviour cannot be explained by a single component model. We discuss other possible interpretations, and we find that a model that incorporates a long-lived reverse shock and forward shock fits the temporal and spectral properties of GRB100814 the best.

The Geomagnetic Field During a Reversal

NASA Technical Reports Server (NTRS)

Heirtzler, James R.

2003-01-01

By modifying the IGRF it is possible to learn what may happen to the geomagnetic field during a geomagnetic reversal. If the entire IGRF reverses then the declination and inclination only reverse when the field strength is zero. If only the dipole component of the IGRF reverses a large geomagnetic field remains when the dipole component is zero and he direction of the field at the end of the reversal is not exactly reversed from the directions at the beginning of the reversal.

Single-Cell RT-PCR in Microfluidic Droplets with Integrated Chemical Lysis.

PubMed

Kim, Samuel C; Clark, Iain C; Shahi, Payam; Abate, Adam R

2018-01-16

Droplet microfluidics can identify and sort cells using digital reverse transcription polymerase chain reaction (RT-PCR) signals from individual cells. However, current methods require multiple microfabricated devices for enzymatic cell lysis and PCR reagent addition, making the process complex and prone to failure. Here, we describe a new approach that integrates all components into a single device. The method enables controlled exposure of isolated single cells to a high pH buffer, which lyses cells and inactivates reaction inhibitors but can be instantly neutralized with RT-PCR buffer. Using our chemical lysis approach, we distinguish individual cells' gene expression with data quality equivalent to more complex two-step workflows. Our system accepts cells and produces droplets ready for amplification, making single-cell droplet RT-PCR faster and more reliable.

SAR-revealed slip partitioning on a bending fault plane for the 2014 Northern Nagano earthquake at the northern Itoigawa-Shizuoka tectonic line

NASA Astrophysics Data System (ADS)

Kobayashi, Tomokazu; Morishita, Yu; Yarai, Hiroshi

2018-05-01

By applying conventional cross-track synthetic aperture radar interferometry (InSAR) and multiple aperture InSAR techniques to ALOS-2 data acquired before and after the 2014 Northern Nagano, central Japan, earthquake, a three-dimensional ground displacement field has been successfully mapped. Crustal deformation is concentrated in and around the northern part of the Kamishiro Fault, which is the northernmost section of the Itoigawa-Shizuoka tectonic line. The full picture of the displacement field shows contraction in the northwest-southeast direction, but northeastward movement along the fault strike direction is prevalent in the northeast portion of the fault, which suggests that a strike-slip component is a significant part of the activity of this fault, in addition to a reverse faulting. Clear displacement discontinuities are recognized in the southern part of the source region, which falls just on the previously known Kamishiro Fault trace. We inverted the SAR and GNSS data to construct a slip distribution model; the preferred model of distributed slip on a two-plane fault surface shows a combination of reverse and left-lateral fault motions on a bending east-dipping fault surface with a dip of 30° in the shallow part and 50° in the deeper part. The hypocenter falls just on the estimated deeper fault plane where a left-lateral slip is inferred, whereas in the shallow part, a reverse slip is predominant, which causes surface ruptures on the ground. The slip partitioning may be accounted for by shear stress resulting from a reverse fault slip with left-lateral component at depth, for which a left-lateral slip is suppressed in the shallow part where the reverse slip is inferred. The slip distribution model with a bending fault surface, instead of a single fault plane, produces moment tensor solution with a non-double couple component, which is consistent with the seismically estimated mechanism.

Thermal Signature Identification System (TheSIS)

NASA Technical Reports Server (NTRS)

Merritt, Scott; Bean, Brian

2015-01-01

We characterize both nonlinear and high order linear responses of fiber-optic and optoelectronic components using spread spectrum temperature cycling methods. This Thermal Signature Identification System (TheSIS) provides much more detail than conventional narrowband or quasi-static temperature profiling methods. This detail allows us to match components more thoroughly, detect subtle reversible shifts in performance, and investigate the cause of instabilities or irreversible changes. In particular, we create parameterized models of athermal fiber Bragg gratings (FBGs), delay line interferometers (DLIs), and distributed feedback (DFB) lasers, then subject the alternative models to selection via the Akaike Information Criterion (AIC). Detailed pairing of components, e.g. FBGs, is accomplished by means of weighted distance metrics or norms, rather than on the basis of a single parameter, such as center wavelength.

1,4-Dihydropyrrolo[3,2-b]pyrroles as a Single Component Photoactive Layer: A New Paradigm for Broadband Detection.

PubMed

Canjeevaram Balasubramanyam, Ram Kumar; Kandjani, Ahmad E; Harrison, Christopher J; Abdul Haroon Rashid, Syed Sulthan Alaudeen; Sabri, Ylias M; Bhargava, Suresh K; Narayan, Ramanuj; Basak, Pratyay; Ippolito, Samuel J

2017-08-23

Single component organic photodetectors capable of broadband light sensing represent a paradigm shift for designing flexible and inexpensive optoelectronic devices. The present study demonstrates the application of a new quadrupolar 1,4-dihydropyrrolo[3,2-b]pyrrole derivative with spectral sensitivity across 350-830 nm as a potential broadband organic photodetector (OPD) material. The amphoteric redox characteristics evinced from the electrochemical studies are exploited to conceptualize a single component OPD with ITO and Al as active electrodes. The photodiode showed impressive broadband photoresponse to monochromatic light sources of 365, 470, 525, 589, 623, and 830 nm. Current density-voltage (J-V) and transient photoresponse studies showed stable and reproducible performance under continuous on/off modulations. The devices operating in reverse bias at 6 V displayed broad spectral responsivity (R) and very good detectivity (D*) peaking a maximum 0.9 mA W -1 and 1.9 × 10 10 Jones (at 623 nm and 500 μW cm -2 ) with a fast rise and decay times of 75 and 140 ms, respectively. Low dark current densities ranging from 1.8 × 10 -10 Acm -2 at 1 V to 7.2 × 10 -9 A cm -2 at 6 V renders an operating range to amplify the photocurrent signal, spectral responsivity, and detectivity. Interestingly, the fabricated OPDs display a self-operational mode which is rarely reported for single component organic systems.

Three component vibrational time reversal communication

DOE PAGES

Anderson, Brian E.; Ulrich, Timothy J.; Ten Cate, James A.

2015-01-01

Time reversal provides an optimal prefilter matched signal to apply to a communication signal before signal transmission. Time reversal allows compensation for wave speed dispersion and can function well in reverberant environments. Time reversal can be used to focus elastic energy to each of the three components of motion independently. A pipe encased in concrete was used to demonstrate the ability to conduct communications of information using three component time reversal. Furthermore, the ability of time reversal to compensate for multi-path distortion (overcoming reverberation) will be demonstrated and the rate of signal communication will be presented. [The U.S. Department ofmore » Energy, through the LANL/LDRD Program, is gratefully acknowledged for supporting this work.]« less

PageRank and rank-reversal dependence on the damping factor

NASA Astrophysics Data System (ADS)

Son, S.-W.; Christensen, C.; Grassberger, P.; Paczuski, M.

2012-12-01

PageRank (PR) is an algorithm originally developed by Google to evaluate the importance of web pages. Considering how deeply rooted Google's PR algorithm is to gathering relevant information or to the success of modern businesses, the question of rank stability and choice of the damping factor (a parameter in the algorithm) is clearly important. We investigate PR as a function of the damping factor d on a network obtained from a domain of the World Wide Web, finding that rank reversal happens frequently over a broad range of PR (and of d). We use three different correlation measures, Pearson, Spearman, and Kendall, to study rank reversal as d changes, and we show that the correlation of PR vectors drops rapidly as d changes from its frequently cited value, d0=0.85. Rank reversal is also observed by measuring the Spearman and Kendall rank correlation, which evaluate relative ranks rather than absolute PR. Rank reversal happens not only in directed networks containing rank sinks but also in a single strongly connected component, which by definition does not contain any sinks. We relate rank reversals to rank pockets and bottlenecks in the directed network structure. For the network studied, the relative rank is more stable by our measures around d=0.65 than at d=d0.

Reversible on-surface wiring of resistive circuits.

PubMed

Inkpen, Michael S; Leroux, Yann R; Hapiot, Philippe; Campos, Luis M; Venkataraman, Latha

2017-06-01

Whilst most studies in single-molecule electronics involve components first synthesized ex situ , there is also great potential in exploiting chemical transformations to prepare devices in situ . Here, as a first step towards this goal, we conduct reversible reactions on monolayers to make and break covalent bonds between alkanes of different lengths, then measure the conductance of these molecules connected between electrodes using the scanning tunneling microscopy-based break junction (STM-BJ) method. In doing so, we develop the critical methodology required for assembling and disassembling surface-bound single-molecule circuits. We identify effective reaction conditions for surface-bound reagents, and importantly demonstrate that the electronic characteristics of wires created in situ agree with those created ex situ . Finally, we show that the STM-BJ technique is unique in its ability to definitively probe surface reaction yields both on a local (∼50 nm 2 ) and pseudo-global (≥10 mm 2 ) level. This investigation thus highlights a route to the construction and integration of more complex, and ultimately functional, surface-based single-molecule circuitry, as well as advancing a methodology that facilitates studies beyond the reach of traditional ex situ synthetic approaches.

Single Active Site Mutation Causes Serious Resistance of HIV Reverse Transcriptase to Lamivudine: Insight from Multiple Molecular Dynamics Simulations.

PubMed

Moonsamy, Suri; Bhakat, Soumendranath; Walker, Ross C; Soliman, Mahmoud E S

2016-03-01

Molecular dynamics simulations, binding free energy calculations, principle component analysis (PCA), and residue interaction network analysis were employed in order to investigate the molecular mechanism of M184I single mutation which played pivotal role in making the HIV-1 reverse transcriptase (RT) totally resistant to lamivudine. Results showed that single mutations at residue 184 of RT caused (1) distortion of the orientation of lamivudine in the active site due to the steric conflict between the oxathiolane ring of lamivudine and the side chain of beta-branched amino acids Ile at position 184 which, in turn, perturbs inhibitor binding, (2) decrease in the binding affinity by (~8 kcal/mol) when compared to the wild-type, (3) variation in the overall enzyme motion as evident from the PCA for both systems, and (4) distortion of the hydrogen bonding network and atomic interactions with the inhibitor. The comprehensive analysis presented in this report can provide useful information for understanding the drug resistance mechanism against lamivudine. The results can also provide some potential clues for further design of novel inhibitors that are less susceptible to drug resistance.

Swimming Back and Forth Using Planar Flagellar Propulsion at Low Reynolds Numbers.

PubMed

Khalil, Islam S M; Tabak, Ahmet Fatih; Hamed, Youssef; Mitwally, Mohamed E; Tawakol, Mohamed; Klingner, Anke; Sitti, Metin

2018-02-01

Peritrichously flagellated Escherichia coli swim back and forth by wrapping their flagella together in a helical bundle. However, other monotrichous bacteria cannot swim back and forth with a single flagellum and planar wave propagation. Quantifying this observation, a magnetically driven soft two-tailed microrobot capable of reversing its swimming direction without making a U-turn trajectory or actively modifying the direction of wave propagation is designed and developed. The microrobot contains magnetic microparticles within the polymer matrix of its head and consists of two collinear, unequal, and opposite ultrathin tails. It is driven and steered using a uniform magnetic field along the direction of motion with a sinusoidally varying orthogonal component. Distinct reversal frequencies that enable selective and independent excitation of the first or the second tail of the microrobot based on their tail length ratio are found. While the first tail provides a propulsive force below one of the reversal frequencies, the second is almost passive, and the net propulsive force achieves flagellated motion along one direction. On the other hand, the second tail achieves flagellated propulsion along the opposite direction above the reversal frequency.

Self-reverse-biased solar panel optical receiver for simultaneous visible light communication and energy harvesting.

PubMed

Shin, Won-Ho; Yang, Se-Hoon; Kwon, Do-Hoon; Han, Sang-Kook

2016-10-31

We propose a self-reverse-biased solar panel optical receiver for energy harvesting and visible light communication. Since the solar panel converts an optical component into an electrical component, it provides both energy harvesting and communication. The signal component can be separated from the direct current component, and these components are used for communication and energy harvesting. We employed a self-reverse-biased receiver circuit to improve the communication and energy harvesting performance. The reverse bias on the solar panel improves the responsivity and response time. The proposed system achieved 17.05 mbps discrete multitone transmission with a bit error rate of 1.1 x 10^-3 and enhanced solar energy conversion efficiency.

Teaching foundational perspective-taking skills to children with autism using the PEAK-T curriculum: single-reversal "I-You" deictic frames.

PubMed

Belisle, Jordan; Dixon, Mark R; Stanley, Caleb R; Munoz, Bridget; Daar, Jacob H

2016-12-01

We taught basic perspective-taking tasks to 3 children with autism and evaluated their ability to derive mutually entailed single-reversal deictic relations of those newly established perspective-taking skills. Furthermore, we examined the possibility of transfers of perspective-taking function to novel untrained stimuli. The methods were taken from the PEAK-T training curriculum, and results yielded positive gains for all 3 children to learn basic perspective taking as well as for 2 of the 3 to derive untrained single-reversal I relations following direct training of single-reversal You relations. All participants demonstrated a transfer of stimulus function to untrained stimuli after the single-reversal deictic relations had been mastered. © 2016 Society for the Experimental Analysis of Behavior.

A design of a high speed dual spectrometer by single line scan camera

NASA Astrophysics Data System (ADS)

Palawong, Kunakorn; Meemon, Panomsak

2018-03-01

A spectrometer that can capture two orthogonal polarization components of s light beam is demanded for polarization sensitive imaging system. Here, we describe the design and implementation of a high speed spectrometer for simultaneous capturing of two orthogonal polarization components, i.e. vertical and horizontal components, of light beam. The design consists of a polarization beam splitter, two polarization-maintain optical fibers, two collimators, a single line-scan camera, a focusing lens, and a reflection blaze grating. The alignment of two beam paths was designed to be symmetrically incident on the blaze side and reverse blaze side of reflection grating, respectively. The two diffracted beams were passed through the same focusing lens and focused on the single line-scan sensors of a CMOS camera. The two spectra of orthogonal polarization were imaged on 1000 pixels per spectrum. With the proposed setup, the amplitude and shape of the two detected spectra can be controlled by rotating the collimators. The technique for optical alignment of spectrometer will be presented and discussed. The two orthogonal polarization spectra can be simultaneously captured at a speed of 70,000 spectra per second. The high speed dual spectrometer can simultaneously detected two orthogonal polarizations, which is an important component for the development of polarization-sensitive optical coherence tomography. The performance of the spectrometer have been measured and analyzed.

Sensorineural Tinnitus: Its Pathology and Probable Therapies

PubMed Central

Møller, Aage R.

2016-01-01

Tinnitus is not a single disease but a group of different diseases with different pathologies and therefore different treatments. Regarding tinnitus as a single disease is hampering progress in understanding of the pathophysiology of tinnitus and perhaps, more importantly, it is a serious obstacle in development of effective treatments for tinnitus. Subjective tinnitus is a phantom sound that takes many different forms and has similarities with chronic neuropathic pain. The pathology may be in the cochlea, in the auditory nerve, or, most commonly, in the brain. Like chronic neuropathic pain tinnitus is not life threatening but influences many normal functions such as sleep and the ability to concentrate on work. Some forms of chronic tinnitus have two components, a (phantom) sound and a component that may best be described as suffering or distress. The pathology of these two components may be different and the treatment that is most effective may be different for these two components. The most common form of treatment of tinnitus is pharmacological agents and behavioral treatment combined with sound therapy. Less common treatments are hypnosis and acupuncture. Various forms of neuromodulation are becoming in use in an attempt to reverse maladaptive plastic changes in the brain. PMID:26977153

Irreversible evolution of angular-dependent coercivity in Fe80Ni20 nanowire arrays: Detection of a single vortex state

NASA Astrophysics Data System (ADS)

Alikhani, M.; Ramazani, A.; Almasi Kashi, M.; Samanifar, S.; Montazer, A. H.

2016-09-01

The irreversible evolution of magnetic coercivity in arrays of 75 nm diameter Fe80Ni20 nanowires (NWs) has been explored by means of first-order reversal curve (FORC) analysis as a function of the angle between the magnetic field and the NW axis (0°≤θ≤90°). The Fe80Ni20 NWs with lengths up to 60 μm were fabricated using a pulsed electrodeposition method into hard-anodic aluminum oxide templates with an interpore distance of 275 nm. Investigating the interwire and intrawire magnetostatic interactions, the angular FORC (AFORC) diagrams indicated enhanced intrawire interactions with increasing length and θ (<90°), induced by a magnetization reversal through vortex domain wall (VDW) propagation. Intriguingly, in addition to the VDW mode, a single vortex state with broad irreversible switching of nucleation and annihilation fields was detected at θ=83° for 60 μm long NWs. At θ=90°, the NWs reversed magnetization through transverse domain wall, involving a reversible component by a fraction of 95%. Furthermore, the transition angle between the reversal modes was found to decrease with increasing aspect ratio from 200 to 800. The irreversible angular-dependent coercivity (HcIrrev(θ)) of Fe80Ni20 NWs was extracted from the AFORC measurements and compared with the major angular dependence of coercivity (HcMajor(θ)) obtained from the conventional hysteresis loop measurements. While HcMajor(θ) showed a non-monotonic behavior, HcIrrev(θ) constantly increased with increasing θ (<90°). On the other hand, using analytical models, a 93% agreement was obtained between the theoretical angular-dependent nucleation field and experimental HcIrrev(θ) for irreversible switching of VDW when 0°≤θ≤86°.

Specific and reversible DNA-directed self-assembly of oil-in-water emulsion droplets

PubMed Central

Hadorn, Maik; Boenzli, Eva; Sørensen, Kristian T.; Fellermann, Harold; Eggenberger Hotz, Peter; Hanczyc, Martin M.

2012-01-01

Higher-order structures that originate from the specific and reversible DNA-directed self-assembly of microscopic building blocks hold great promise for future technologies. Here, we functionalized biotinylated soft colloid oil-in-water emulsion droplets with biotinylated single-stranded DNA oligonucleotides using streptavidin as an intermediary linker. We show the components of this modular linking system to be stable and to induce sequence-specific aggregation of binary mixtures of emulsion droplets. Three length scales were thereby involved: nanoscale DNA base pairing linking microscopic building blocks resulted in macroscopic aggregates visible to the naked eye. The aggregation process was reversible by changing the temperature and electrolyte concentration and by the addition of competing oligonucleotides. The system was reset and reused by subsequent refunctionalization of the emulsion droplets. DNA-directed self-assembly of oil-in-water emulsion droplets, therefore, offers a solid basis for programmable and recyclable soft materials that undergo structural rearrangements on demand and that range in application from information technology to medicine. PMID:23175791

Reversible Hydrogen Activation by a Pyridonate Borane Complex: Combining Frustrated Lewis Pair Reactivity with Boron-Ligand Cooperation.

PubMed

Gellrich, Urs

2018-04-16

A pyridone borane complex that liberates dihydrogen under mild conditions is described. The reverse reaction, dihydrogen activation by the formed pyridonate borane complex, is achieved under moderate H 2 pressure (2 bar) at room temperature. DFT and DLPNO-CCSD(T) computations reveal that the active form of the pyridonate borane complex is a boroxypyridine that can be described as a single component frustrated Lewis pair (FLP). Significantly, the boroxypyridine undergoes a chemical transformation to a neutral pyridone donor ligand in the course of the hydrogen activation. This unprecedented mode of action may thus, in analogy to metal-ligand cooperation, be regarded as an example of boron-ligand cooperation. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidic chip for peptide analysis with an integrated HPLC column, sample enrichment column, and nanoelectrospray tip.

PubMed

Yin, Hongfeng; Killeen, Kevin; Brennen, Reid; Sobek, Dan; Werlich, Mark; van de Goor, Tom

2005-01-15

Current nano-LC/MS systems require the use of an enrichment column, a separation column, a nanospray tip, and the fittings needed to connect these parts together. In this paper, we present a microfabricated approach to nano-LC, which integrates these components on a single LC chip, eliminating the need for conventional LC connections. The chip was fabricated by laminating polyimide films with laser-ablated channels, ports, and frit structures. The enrichment and separation columns were packed using conventional reversed-phase chromatography particles. A face-seal rotary valve provided a means for switching between sample loading and separation configurations with minimum dead and delay volumes while allowing high-pressure operation. The LC chip and valve assembly were mounted within a custom electrospray source on an ion-trap mass spectrometer. The overall system performance was demonstrated through reversed-phase gradient separations of tryptic protein digests at flow rates between 100 and 400 nL/min. Microfluidic integration of the nano-LC components enabled separations with subfemtomole detection sensitivity, minimal carryover, and robust and stable electrospray throughout the LC solvent gradient.

Entropy-stabilized oxides

PubMed Central

Rost, Christina M.; Sachet, Edward; Borman, Trent; Moballegh, Ali; Dickey, Elizabeth C.; Hou, Dong; Jones, Jacob L.; Curtarolo, Stefano; Maria, Jon-Paul

2015-01-01

Configurational disorder can be compositionally engineered into mixed oxide by populating a single sublattice with many distinct cations. The formulations promote novel and entropy-stabilized forms of crystalline matter where metal cations are incorporated in new ways. Here, through rigorous experiments, a simple thermodynamic model, and a five-component oxide formulation, we demonstrate beyond reasonable doubt that entropy predominates the thermodynamic landscape, and drives a reversible solid-state transformation between a multiphase and single-phase state. In the latter, cation distributions are proven to be random and homogeneous. The findings validate the hypothesis that deliberate configurational disorder provides an orthogonal strategy to imagine and discover new phases of crystalline matter and untapped opportunities for property engineering. PMID:26415623

Inconsistent magnetic polarities in magnetite- and greigite-bearing sediments: Understanding complex magnetizations in the late Messinian in the Adana Basin (southern Turkey)

NASA Astrophysics Data System (ADS)

Lucifora, Stella; Cifelli, Francesca; Mattei, Massimo; Sagnotti, Leonardo; Cosentino, Domenico; Roberts, Andrew P.

2012-10-01

We present paleomagnetic, rock magnetic and scanning electron microscope data from three upper Messinian stratigraphic sections from the Adana Basin (southern Turkey). The collected samples are from fine-grained units, which were deposited during the Messinian Salinity Crisis (within subchron C3r). Paleomagnetic results reveal an inconsistent polarity record, related to a mixture of magnetite and greigite that hinders determination of a reliable magnetostratigraphy. Three classes of samples are recognized on the basis of paleomagnetic results. The first is characterized by a single magnetization component, with normal polarity, that is stable up to 530-580°C and is carried by magnetite. The second is characterized by a single magnetization component, with reversed polarity, that is stable up to 330-420°C. This magnetization is due to greigite, which developed after formation of slumps and before tectonic tilting of the studied successions. The third is characterized by reversed polarity, which is stable up to 530-580°C. We interpret this component as a primary magnetization carried by fine-grained and magnetically stable detrital magnetite. Results indicate that in the Adana Basin the assumption that a primary magnetization is carried by magnetite, and a magnetic overprint carried by greigite, does not hold because a late magnetic overprint has also been found for magnetite-bearing samples. Our data illustrate the complexity of magnetostratigraphic reconstructions in successions characterized by variable mixtures of magnetic minerals with different magnetic stability that formed at different stages. We demonstrate the need to perform detailed magnetic mineralogy analyses when conducting magnetostratigraphic studies of clay-rich sediments from marine or lacustrine environments.

Irreversible and reversible components in the genesis of hypertension by sodium chloride (salt).

PubMed

Tekol, Yalcin

2008-01-01

Despite the abundant studies and overwhelming evidences demonstrating the essential role of salt (sodium chloride) for developing "essential" hypertension (EH), the controversies about salt-hypertension (HT) relations are still continuing. One of important mistakes in this topic is assuming that the HT-producing effect of salt is reversible. The present paper explains the complex nature of salt-HT relations. The deduction was made basing on the studies which investigate the relations between salt and HT. Animal experiments show that HT-producing effect of salt contains irreversible and reversible components. The existence of irreversible component manifests itself in this way: the blood pressure (BP) does not recede to the natural values despite removing of salt exposure. The proportion of BP decreasing after salt exposure termination belongs to the reversible component. Available evidences indicate that the irreversible component is developed in utero, during suckling and, generally, in prepubertal period secondary to salt exposure, however, if the salt exposure extends over more than one period, the HT may be intensified. The consequences of salt exposure during early life of human beings have not been investigated as detailed as in experimental animals, however, there are some clinical trials and epidemiological observations indicating that, similar to experimental animals, irreversible and reversible components are also developed in man during the genesis of HT. By the introduction of irreversible and reversible components notion, some obscured items on salt-HT relations can be clarified. For example, some intervention studies could not find dramatic relations between salt and HT, because these interventions modify only the reversible component, but irreversible component remains unchanged. As a result, salt exposure is detrimental for each period of life. For eradication of HT, it is prerequisite to prevent all individuals (especially pregnant or lactating women, and children) from salt exposure. In this condition, the new generation will be free from HT.

3D navigated implantation of the glenoid component in reversed shoulder arthroplasty. Feasibility and results in an anatomic study.

PubMed

Stübig, Timo; Petri, Maximilian; Zeckey, Christian; Hawi, Nael; Krettek, Christian; Citak, Musa; Meller, Rupert

2013-12-01

Reversed shoulder arthroplasty is an alternative to total shoulder arthroplasty for various indications. The long-term results depend on stable bone fixation, and correct positioning of the glenoid component. The potential contribution of image guidance for reversed shoulder arthroplasty procedures was tested in vitro. 27 positioning procedures (15 navigated, 12 non-navigated) of the glenoid baseplate in reverse shoulder arthroplasty were performed by a single experienced orthopaedic surgeon. A Kirschner wire was placed freehand or with the use of a navigated drill guide. For the navigated procedures, a flat detector 3D C-arm with navigation system was used. The Kirschner wire was to be inserted 12 mm from the inferior glenoid, with an inferior tilt of 10° and centrally in the axial scapular axis. The insertion point in the glenoid as well as the position of the K-wire in the axial and sagittal planes were measured. For statistical analysis, t-tests were performed with a significance level of 0.05. The inferior glenoid drilling distance was 14.1 ± 3.4 mm for conventional placement and 15.1 ± 3.4 mm for the navigated procedure (P = 0.19). The inferior tilt showed no significant difference between the two methods (conventional 7.4 ± 5.2°, navigated 7.7 ± 4.9°, P = 0.63). The glenoid version in the axial plane showed significantly higher accuracy for the navigated procedure, with a mean deviation of 1.6 ±4.5° for the navigated procedure compared with 11.5 ± 6.5° for the conventional procedure(P = 0.004). Accurate positioning of the glenoidal baseplate in the axial scapular plane can be improved using 3D C-arm navigation for reversed shoulder arthroplasty. However, computer navigation may not improve the inferior tilt of the component or the position in the inferior glenoid to avoid scapular notching. Nevertheless, further studies are required to confirm these findings in the clinical setup. Copyright © 2013 John Wiley & Sons, Ltd.

Immunocontraceptive activity guided fractionation and characterization of active constituents of neem (Azadirachta indica) seed extracts.

PubMed

Garg, S; Talwar, G P; Upadhyay, S N

1998-04-01

A novel approach for immunocontraception by intervention of local cell mediated immunity in the reproductive system by using single intrauterine application of neem oil has been described earlier. The reversible block in fertility was reported to last for 107-180 days in female Wistar rats (Upadhyay et al., 1990. Antifertility effects of neem oil by single intrauterine administration: A novel method of contraception. Proceedings Of The Royal Society Of London B 242, 175-180) and 7-11 months in monkeys (Upadhyay et al., 1994. Long term contraceptive effects of intrauterine neem treatment (IUNT) in bonnet monkeys: An alternative to intrauterine contraceptive devices. Contraception 49, 161-167). The present study, describes the identification and characterization of the biologically active fraction from neem seeds (Azadirachta indica A. Juss. Family Meliaceae), responsible for the above activity in adult female Wistar rats. Initial studies with the mechanically extracted oil and solvent extracts of neem seeds have revealed that the antifertility activity was present in constituents of low to intermediate polarity. A hexane extract of neem seeds was reported to be biologically active (Garg et al., 1994. Comparison of extraction procedures on the immunocontraceptive activity of neem seed extracts. Journal of Ethnopharmacology 22, 87-92). Subsequently, hexane extract was sequentially fractionated through the last active fraction using various separation techniques and tested for antifertility activity at each step. Preparative HPLC was used for isolating individual components of the active fraction in quantities, sufficient for characterization. An analytical HPLC method was developed for standardization of the fraction. The active fraction was identified to be a mixture of six components, which comprises of saturated, mono and di-unsaturated free fatty acids and their methyl esters. Dose response study was performed with the last active fractions. The antifertility activity with the active fraction was reversible in nature and it was completely active until 5% concentration. There was no systemic toxic effect following the administration of the active fraction. This study, for the first time, proposes an active fraction from neem seeds, responsible for long term and reversible blocking of fertility after a single intrauterine administration with high efficacy.

Three-dimensional time reversal communications in elastic media

DOE PAGES

Anderson, Brian E.; Ulrich, Timothy J.; Le Bas, Pierre-Yves; ...

2016-02-23

Our letter presents a series of vibrational communication experiments, using time reversal, conducted on a set of cast iron pipes. Time reversal has been used to provide robust, private, and clean communications in many underwater acoustic applications. Also, the use of time reversal to communicate along sections of pipes and through a wall is demonstrated here in order to overcome the complications of dispersion and multiple scattering. These demonstrations utilize a single source transducer and a single sensor, a triaxial accelerometer, enabling multiple channels of simultaneous communication streams to a single location.

Extremely low-frequency magnetic fields can impair spermatogenesis recovery after reversible testicular damage induced by heat.

PubMed

Tenorio, Bruno Mendes; Ferreira Filho, Moisés Bonifacio Alves; Jimenez, George Chaves; de Morais, Rosana Nogueira; Peixoto, Christina Alves; Nogueira, Romildo de Albuquerque; da Silva Junior, Valdemiro Amaro

2014-06-01

Male infertility is often related to reproductive age couples experiencing fertility-related issues. Men may have fertility problems associated with reversible testicular damage. Considering that men have been increasingly exposed to extremely low-frequency magnetic fields generated by the production, distribution and use of electricity, this study analyzed whether 60 Hz and 1 mT magnetic field exposure may impair spermatogenesis recovery after reversible testicular damage induced by heat shock using rats as an experimental model. Adult male rats were subjected to a single testicular heat shock (HS, 43 °C for 12 min) and then exposed to the magnetic field for 15, 30 and 60 d after HS. Magnetic field exposure during the spermatogenesis recovery induced changes in testis components volume, cell ultrastructure and histomorphometrical parameters. Control animals had a reestablished and active spermatogenesis at 60 d after heat shock, while animals exposed to magnetic field still showed extensive testicular degeneration. Magnetic field exposure did not change the plasma testosterone. In conclusion, extremely low-frequency magnetic field may be harmful to fertility recovery in males affected by reversible testicular damage.

Environmental enrichment reverses memory impairment induced by toluene in mice.

PubMed

Montes, Sergio; Solís-Guillén, Rocío Del Carmen; García-Jácome, David; Páez-Martínez, Nayeli

2017-05-01

Toluene is the main component of a variety of inhalants that are used for intoxication purposes. Alterations in memory have been reported in inhalant users; however, it is unclear whether these impairments could be reversed, and the mechanisms involved in the putative recovery. Therefore, the main purpose of this study was to model the deleterious effects of toluene on memory in mice and to evaluate the effect of environmental enrichment on that response. In the second part of the study, the concentrations of glutamate and GABA, following chronic toluene exposure and after environmental enrichment treatment, were evaluated. Adolescent mice were exposed to either a single or repeated schedule of toluene administration and their responses to object recognition were analyzed. An independent group of mice was repeatedly exposed to toluene and then housed either under environmental enrichment or standard conditions for four weeks. At the end of the housing period, the rodents' performance in object recognition test, as well as the concentrations of neurotransmitters, were analyzed. The results showed that toluene caused memory impairment in mice that received a single or repeated solvent exposure. Remarkably, environmental enrichment could reverse memory deficits induced by repeated administration of toluene. Cessation of toluene exposure in mice in standard housing did not produce that response. The glutamate and GABA tissue contents were not involved in the effects of toluene or environmental enrichment of memory. Copyright © 2017. Published by Elsevier Inc.

Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

NASA Astrophysics Data System (ADS)

Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

1993-03-01

Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

Reverse polarity magnetized melt rocks from the Chicxulub impact structure, Yucatan Peninsula, Mexico

NASA Technical Reports Server (NTRS)

Urrutia-Fucugauchi, Jaime; Marin, Luis E.; Sharpton, Virgil L.; Quezada, Juan Manuel

1993-01-01

Further paleomagnetic data for core samples of melt rock recovered in the Petroleos Mexicanos (PEMEX) exploratory wells within the Chicxulub structure, northern Yucatan peninsula, Mexico are reported. A previous report by Sharpton showed that the rocks studied contain high iridium levels and shocked breccia clasts, and an Ar-40/Ar-39 age of 65.2 plus or minus 0.4 Ma. The geomagnetic polarity determined for two samples is reverse (R) and was correlated with chron 29R that includes the K/T boundary. Our present analysis is based on two samples from each of three clasts of the melt rock from PEMEX well Y6-N17 (1295 to 1299 m b.s.l.). This study concentrates on the vectorial nature and stability of the remanence (NRM), the magnetic mineralogy and remanence carriers (i.e., the reliability and origin of the record), and on the implications (correlation with expected paleolatitude and polarity). The relative orientation of the drill core samples with respect to the horizontal is known. Samples were stable under alternating field (AF) and thermal treatments, and after removal of a small component they exhibited single-vectorial behavior. The characteristic remanence inclinations show small dispersion and a mean value (-43 deg) in close agreement with the expected inclination and paleolatitude (derived from the North American apparent polar wander path). Isothermal remenence (IRM) acquisition experiments, Lowrie-Fuller tests, coercivity and unblocking temperature spectra of NRM and saturation IRM, susceptibility and Q-coefficient analyses, and the single-component nature indicate a dominant mineralogy of iron-rich titanomagnetites with single or pseduo-single domain states. The stable characteristic magnetization may be interpreted as a result of shock heating of the rock at the time of formation of the inpact structure and its polarity, age, and paleolatitude are consistent with a time about the K/T boundary.

Characterizing the nature of subpulse drifting in pulsars

NASA Astrophysics Data System (ADS)

Basu, Rahul; Mitra, Dipanjan

2018-04-01

We report a detailed study of subpulse drifting in four long-period pulsars. These pulsars were observed in the Meterwavelength Single-pulse Polarimetric Emission Survey and the presence of phase-modulated subpulse drifting was reported in each case. We carried out longer duration and more sensitive observations lasting 7000-12 000 periods in the frequency range 306-339 MHz. The drifting features were characterized in great detail, including the phase variations across the pulse window. For two pulsars, J0820-1350 and J1720-2933, the phases changed steadily across the pulse window. The pulsar J1034-3224 has five components. The leading component was very weak and was barely detectable in our single-pulse observations. The four trailing components showed subpulse drifting. The phase variations changed in alternate components with a reversal in the sign of the gradient. This phenomenon is known as bi-drifting. The pulsar J1555-3134 showed two distinct peak frequencies of comparable strengths in the fluctuation spectrum. The two peaks did not appear to be harmonically related and were most likely a result of different physical processes. Additionally, the long observations enabled us to explore the temporal variations of the drifting features. The subpulse drifting was largely constant with time but small fluctuations around a mean value were seen.

Superconductivity. Observation of broken time-reversal symmetry in the heavy-fermion superconductor UPt₃.

PubMed

Schemm, E R; Gannon, W J; Wishne, C M; Halperin, W P; Kapitulnik, A

2014-07-11

Models of superconductivity in unconventional materials can be experimentally differentiated by the predictions they make for the symmetries of the superconducting order parameter. In the case of the heavy-fermion superconductor UPt3, a key question is whether its multiple superconducting phases preserve or break time-reversal symmetry (TRS). We tested for asymmetry in the phase shift between left and right circularly polarized light reflected from a single crystal of UPt3 at normal incidence and found that this so-called polar Kerr effect appears only below the lower of the two zero-field superconducting transition temperatures. Our results provide evidence for broken TRS in the low-temperature superconducting phase of UPt3, implying a complex two-component order parameter for superconductivity in this system. Copyright © 2014, American Association for the Advancement of Science.

Reversing the Landauer's erasure: Single-electron Maxwell's demon operating at the limit of thermodynamic efficiency

NASA Astrophysics Data System (ADS)

Averin, Dmitri V.; Pekola, Jukka P.

2017-03-01

According to Landauer's principle, erasure of information is the only part of a computation process that unavoidably involves energy dissipation. If done reversibly, such an erasure generates the minimal heat of $k_BT\\ln 2$ per erased bit of information. The goal of this work is to discuss the actual reversal of the optimal erasure which can serve as the basis for the Maxwell's demon operating with ultimate thermodynamic efficiency as dictated by the second law of thermodynamics. The demon extracts $k_BT\\ln 2$ of heat from an equilibrium reservoir at temperature $T$ per one bit of information obtained about the measured system used by the demon. We have analyzed this Maxwell's demon in the situation when it uses a general quantum system with a discrete spectrum of energy levels as its working body. In the case of the effectively two-level system, which has been realized experimentally based on tunneling of individual electron in a single-electron box [J.V. Koski et al., PNAS 111, 13786 (2014)], we also studied and minimized corrections to the ideal reversible operation of the demon. These corrections include, in particular, the non-adiabatic terms which are described by a version of the classical fluctuation-dissipation theorem. The overall reversibility of the Maxwell's demon requires, beside the reversibility of the intrinsic working body dynamics, the reversibility of the measurement and feedback processes. The single-electron demon can, in principle, be made fully reversible by developing a thermodynamically reversible single-electron charge detector for measurements of the individual charge states of the single-electron box.

Selective interface transparency in graphene nanoribbon based molecular junctions.

PubMed

Dou, K P; Kaun, C C; Zhang, R Q

2018-03-08

A clear understanding of electrode-molecule interfaces is a prerequisite for the rational engineering of future generations of nanodevices that will rely on single-molecule coupling between components. With a model system, we reveal a peculiar dependence on interfaces in all graphene nanoribbon-based carbon molecular junctions. The effect can be classified into two types depending on the intrinsic feature of the embedded core graphene nanoflake (GNF). For metallic GNFs with |N A - N B | = 1, good/poor contact transparency occurs when the core device aligns with the center/edge of the electrode. The situation is reversed when a semiconducting GNF is the device, where N A = N B . These results may shed light on the design of real connecting components in graphene-based nanocircuits.

Production Planning and Simulation for Reverse Supply Chain

NASA Astrophysics Data System (ADS)

Murayama, Takeshi; Yoda, Mitsunobu; Eguchi, Toru; Oba, Fuminori

This paper describes a production planning method for a reverse supply chain, in which a disassembly company takes reusable components from returned used products and supplies the reusable components for a product manufacturer. This method addresses the issue that the timings and quantities of returned products and reusable components obtained from them are unknown. This method first predicts the quantities of returned products and reusable components at each time period by using reliability models. Using the prediction result, the method performs production planning based on Material Requirements Planning (MRP). This method enables us to plan at each time period: the quantity of the products to be disassembled; the quantity of the reusable components to be used; and the quantity of the new components to be produced. The flow of the components and products through a forward and reverse supply chain is simulated to show the effectiveness of the method.

Online combination of reversed-phase/reversed-phase and porous graphitic carbon liquid chromatography for multicomponent separation of proteomics and glycoproteomics samples.

PubMed

Lam, Maggie P Y; Lau, Edward; Siu, S O; Ng, Dominic C M; Kong, Ricky P W; Chiu, Philip C N; Yeung, William S B; Lo, Clive; Chu, Ivan K

2011-11-01

In this paper, we describe an online combination of reversed-phase/reversed-phase (RP-RP) and porous graphitic carbon (PGC) liquid chromatography (LC) for multicomponent analysis of proteomics and glycoproteomics samples. The online RP-RP portion of this system provides comprehensive 2-D peptide separation based on sequence hydrophobicity at pH 2 and 10. Hydrophilic components (e.g. glycans, glycopeptides) that are not retained by RP are automatically diverted downstream to a PGC column for further trapping and separation. Furthermore, the RP-RP/PGC system can provide simultaneous extension of the hydropathy range and peak capacity for analysis. Using an 11-protein mixture, we found that the system could efficiently separate native peptides and released N-glycans from a single sample. We evaluated the applicability of the system to the analysis of complex biological samples using 25 μg of the lysate of a human choriocarcinoma cell line (BeWo), confidently identifying a total of 1449 proteins from a single experiment and up to 1909 distinct proteins from technical triplicates. The PGC fraction increased the sequence coverage through the inclusion of additional hydrophilic sequences that accounted for up to 6.9% of the total identified peptides from the BeWo lysate, with apparent preference for the detection of hydrophilic motifs and proteins. In addition, RP-RP/PGC is applicable to the analysis of complex glycomics samples, as demonstrated by our analysis of a concanavalin A-extracted glycoproteome from human serum; in total, 134 potentially N-glycosylated serum proteins, 151 possible N-glycosylation sites, and more than 40 possible N-glycan structures recognized by concanavalin A were simultaneously detected. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Response properties in the adsorption-desorption model on a triangular lattice

NASA Astrophysics Data System (ADS)

Šćepanović, J. R.; Stojiljković, D.; Jakšić, Z. M.; Budinski-Petković, Lj.; Vrhovac, S. B.

2016-06-01

The out-of-equilibrium dynamical processes during the reversible random sequential adsorption (RSA) of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. We focused on the influence of the order of symmetry axis of the shape on the response of the reversible RSA model to sudden perturbations of the desorption probability Pd. We provide a detailed discussion of the significance of collective events for governing the time coverage behavior of shapes with different rotational symmetries. We calculate the two-time density-density correlation function C(t ,tw) for various waiting times tw and show that longer memory of the initial state persists for the more symmetrical shapes. Our model displays nonequilibrium dynamical effects such as aging. We find that the correlation function C(t ,tw) for all objects scales as a function of single variable ln(tw) / ln(t) . We also study the short-term memory effects in two-component mixtures of extended objects and give a detailed analysis of the contribution to the densification kinetics coming from each mixture component. We observe the weakening of correlation features for the deposition processes in multicomponent systems.

Probing the Hydrogen Enhanced Near-Field Emission of ITO without a Vacuum-Gap

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

Poole, Jacob L.; Yu, Yang; Ohodnicki, Paul R.

In-situ monitoring of the multi-component gas streams in high temperature energy conversion devices offer the promises to higher efficiency via improved understanding of the chemical environments during device operation. While conventional resistive based metal oxide semiconductor gas sensors suffer from strong cross-sensitivity, optical sensing approaches offer intrinsic advantages to achieve gas selectivity based on wavelength specific interactions. This manuscript describes a novel method to achieve multicomponent gas sensing during gas exposure of H2, CO2, CH4and CO in humid high temperature environments. A single sensor element comprised of a perovskite La0.3Sr0.7TiO3(LSTO) oxide thin film layer coated on silica optical fiber wasmore » used. The sensing responses consisted of two wavelength-specific near infrared (NIR) mechanisms, namely broadband absorption associated with the metal oxide layer, and wavelength localized thermal emission responses associated with the hydroxyl defects within the silica fiber. Principal component analysis (PCA) was applied to couple the two mechanisms to achieve selective gas identification. Successful discrimination of H2and CO2on a single fiber sensor was achieved, where the results are both stable and reversible. This design demonstrates that by coupling multiple optical mechanisms on a single oxide coated fiber sensor, simple platforms can also achieve multi-component sensing functionality without the added complexity of a sensor array. Thus, it suggests a new approach to construct simple, robust and functional sensor designs capable of gas discrimination and quantification in multi-component gas streams.« less

Reverse logistics in the Brazilian construction industry.

PubMed

Nunes, K R A; Mahler, C F; Valle, R A

2009-09-01

In Brazil most Construction and Demolition Waste (C&D waste) is not recycled. This situation is expected to change significantly, since new federal regulations oblige municipalities to create and implement sustainable C&D waste management plans which assign an important role to recycling activities. The recycling organizational network and its flows and components are fundamental to C&D waste recycling feasibility. Organizational networks, flows and components involve reverse logistics. The aim of this work is to introduce the concepts of reverse logistics and reverse distribution channel networks and to study the Brazilian C&D waste case.

The C-terminal domain of Tetrahymena thermophila telomerase holoenzyme protein p65 induces multiple structural changes in telomerase RNA

PubMed Central

Akiyama, Benjamin M.; Loper, John; Najarro, Kevin; Stone, Michael D.

2012-01-01

The unique cellular activity of the telomerase reverse transcriptase ribonucleoprotein (RNP) requires proper assembly of protein and RNA components into a functional complex. In the ciliate model organism Tetrahymena thermophila, the La-domain protein p65 is required for in vivo assembly of telomerase. Single-molecule and biochemical studies have shown that p65 promotes efficient RNA assembly with the telomerase reverse transcriptase (TERT) protein, in part by inducing a bend in the conserved stem IV region of telomerase RNA (TER). The domain architecture of p65 consists of an N-terminal domain, a La-RRM motif, and a C-terminal domain (CTD). Using single-molecule Förster resonance energy transfer (smFRET), we demonstrate the p65CTD is necessary for the RNA remodeling activity of the protein and is sufficient to induce a substantial conformational change in stem IV of TER. Moreover, nuclease protection assays directly map the site of p65CTD interaction to stem IV and reveal that, in addition to bending stem IV, p65 binding reorganizes nucleotides that comprise the low-affinity TERT binding site within stem–loop IV. PMID:22315458

Structural and spectral comparisons between isomeric benzisothiazole and benzothiazole based aromatic heterocyclic dyes

NASA Astrophysics Data System (ADS)

Wang, Yin-Ge; Wang, Yue-Hua; Tao, Tao; Qian, Hui-Fen; Huang, Wei

2015-09-01

A pair of isomeric heterocyclic compounds, namely 3-amino-5-nitro-[2,1]-benzisothiazole and 2-amino-6-nitrobenzothiazole, are used as the diazonium components to couple with two N-substituted 4-aminobenzene derivatives. As a result, two pairs of isomeric aromatic heterocyclic azo dyes have been produced and they are structurally and spectrally characterized and compared including single-crystal structures, electronic spectra, solvatochromism and reversible acid-base discoloration, thermal stability and theoretically calculations. It is concluded that both benzisothiazole and benzothiazole based dyes show planar molecular structures and offset π-π stacking interactions, solvatochromism and reversible acid-base discoloration. Furthermore, benzisothiazole based aromatic heterocyclic dyes exhibit higher thermal stability, larger solvatochromic effects and maximum absorption wavelengths than corresponding benzothiazole based ones, which can be explained successfully by the differences of their calculated isomerization energy, dipole moment and molecular band gaps.

Structural optimization of N1-aryl-benzimidazoles for the discovery of new non-nucleoside reverse transcriptase inhibitors active against wild-type and mutant HIV-1 strains.

PubMed

Monforte, Anna Maria; De Luca, Laura; Buemi, Maria Rosa; Agharbaoui, Fatima E; Pannecouque, Christophe; Ferro, Stefania

2018-02-01

Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are recommended components of preferred combination antiretroviral therapies used for the treatment of human immunodeficiency virus (HIV) infection. These regimens are extremely effective in suppressing virus replication. Recently, our research group identified some N 1 -aryl-2-arylthioacetamido-benzimidazoles as a novel class of NNRTIs. In this research work we report the design, the synthesis and the structure-activity relationship studies of new compounds (20-34) in which some structural modifications have been introduced in order to investigate their effects on reverse transcriptase (RT) inhibition and to better define the features needed to increase the antiviral activity. Most of the new compounds proved to be highly effective in inhibiting both RT enzyme at nanomolar concentrations and HIV-1 replication in MT4 cells with minimal cytotoxicity. Among them, the most promising N 1 -aryl-2-arylthioacetamido-benzimidazoles and N 1 -aryl-2-aryloxyacetamido-benzimidazoles were also tested toward a panel of single- and double-mutants strain responsible for resistance to NNRTIs, showing in vitro antiviral activity toward single mutants L100I, K103N, Y181C, Y188L and E138K. The best results were observed for derivatives 29 and 33 active also against the double mutants F227L and V106A. Computational approaches were applied in order to rationalize the potency of the new synthesized inhibitors. Copyright © 2017 Elsevier Ltd. All rights reserved.

A New Efficient Algorithm for the All Sorting Reversals Problem with No Bad Components.

PubMed

Wang, Biing-Feng

2016-01-01

The problem of finding all reversals that take a permutation one step closer to a target permutation is called the all sorting reversals problem (the ASR problem). For this problem, Siepel had an O(n (3))-time algorithm. Most complications of his algorithm stem from some peculiar structures called bad components. Since bad components are very rare in both real and simulated data, it is practical to study the ASR problem with no bad components. For the ASR problem with no bad components, Swenson et al. gave an O (n(2))-time algorithm. Very recently, Swenson found that their algorithm does not always work. In this paper, a new algorithm is presented for the ASR problem with no bad components. The time complexity is O(n(2)) in the worst case and is linear in the size of input and output in practice.

Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises.

PubMed

Comfort, Paul; Jones, Paul Anthony; Smith, Laura Constance; Herrington, Lee

2015-10-01

Unilateral body-weight exercises are commonly used to strengthen the lower limbs during rehabilitation after injury, but data comparing the loading of the limbs during these tasks are limited. To compare joint kinetics and kinematics during 3 commonly used rehabilitation exercises. Descriptive laboratory study. Laboratory. A total of 9 men (age = 22.1 ± 1.3 years, height = 1.76 ± 0.08 m, mass = 80.1 ± 12.2 kg) participated. Participants performed the single-legged squat, forward lunge, and reverse lunge with kinetic data captured via 2 force plates and 3-dimensional kinematic data collected using a motion-capture system. Peak ground reaction forces, maximum joint angles, and peak sagittal-joint moments. We observed greater eccentric and concentric peak vertical ground reaction forces during the single-legged squat than during both lunge variations (P ≤ .001). Both lunge variations demonstrated greater knee and hip angles than did the single-legged squat (P < .001), but we observed no differences between lunges (P > .05). Greater dorsiflexion occurred during the single-legged squat than during both lunge variations (P < .05), but we noted no differences between lunge variations (P = .70). Hip-joint moments were greater during the forward lunge than during the reverse lunge (P = .003) and the single-legged squat (P = .011). Knee-joint moments were greater in the single-legged squat than in the reverse lunge (P < .001) but not greater in the single-legged squat than in the forward lunge (P = .41). Ankle-joint moments were greater during the single-legged squat than during the forward lunge (P = .002) and reverse lunge (P < .001). Appropriate loading progressions for the hip should begin with the single-legged squat and progress to the reverse lunge and then the forward lunge. In contrast, loading progressions for the knee and ankle should begin with the reverse lunge and progress to the forward lunge and then the single-legged squat.

BCS Theory of Time-Reversal-Symmetric Hofstadter-Hubbard Model

NASA Astrophysics Data System (ADS)

Umucalılar, R. O.; Iskin, M.

2017-08-01

The competition between the length scales associated with the periodicity of a lattice potential and the cyclotron radius of a uniform magnetic field is known to have dramatic effects on the single-particle properties of a quantum particle, e.g., the fractal spectrum is known as the Hofstadter butterfly. Having this intricate competition in mind, we consider a two-component Fermi gas on a square optical lattice with opposite synthetic magnetic fields for the components, and study its effects on the many-body BCS-pairing phenomenon. By a careful addressing of the distinct superfluid transitions from the semimetal, quantum spin-Hall insulator, or normal phases, we explore the low-temperature phase diagrams of the model, displaying lobe structures that are reminiscent of the well-known Mott-insulator transitions of the Bose-Hubbard model.

Direct and reverse secret-key capacities of a quantum channel.

PubMed

Pirandola, Stefano; García-Patrón, Raul; Braunstein, Samuel L; Lloyd, Seth

2009-02-06

We define the direct and reverse secret-key capacities of a memoryless quantum channel as the optimal rates that entanglement-based quantum-key-distribution protocols can reach by using a single forward classical communication (direct reconciliation) or a single feedback classical communication (reverse reconciliation). In particular, the reverse secret-key capacity can be positive for antidegradable channels, where no forward strategy is known to be secure. This property is explicitly shown in the continuous variable framework by considering arbitrary one-mode Gaussian channels.

Design of a reversible single precision floating point subtractor.

PubMed

Anantha Lakshmi, Av; Sudha, Gf

2014-01-04

In recent years, Reversible logic has emerged as a major area of research due to its ability to reduce the power dissipation which is the main requirement in the low power digital circuit design. It has wide applications like low power CMOS design, Nano-technology, Digital signal processing, Communication, DNA computing and Optical computing. Floating-point operations are needed very frequently in nearly all computing disciplines, and studies have shown floating-point addition/subtraction to be the most used floating-point operation. However, few designs exist on efficient reversible BCD subtractors but no work on reversible floating point subtractor. In this paper, it is proposed to present an efficient reversible single precision floating-point subtractor. The proposed design requires reversible designs of an 8-bit and a 24-bit comparator unit, an 8-bit and a 24-bit subtractor, and a normalization unit. For normalization, a 24-bit Reversible Leading Zero Detector and a 24-bit reversible shift register is implemented to shift the mantissas. To realize a reversible 1-bit comparator, in this paper, two new 3x3 reversible gates are proposed The proposed reversible 1-bit comparator is better and optimized in terms of the number of reversible gates used, the number of transistor count and the number of garbage outputs. The proposed work is analysed in terms of number of reversible gates, garbage outputs, constant inputs and quantum costs. Using these modules, an efficient design of a reversible single precision floating point subtractor is proposed. Proposed circuits have been simulated using Modelsim and synthesized using Xilinx Virtex5vlx30tff665-3. The total on-chip power consumed by the proposed 32-bit reversible floating point subtractor is 0.410 W.

On the applicability of low-dimensional models for convective flow reversals at extreme Prandtl numbers

NASA Astrophysics Data System (ADS)

Mannattil, Manu; Pandey, Ambrish; Verma, Mahendra K.; Chakraborty, Sagar

2017-12-01

Constructing simpler models, either stochastic or deterministic, for exploring the phenomenon of flow reversals in fluid systems is in vogue across disciplines. Using direct numerical simulations and nonlinear time series analysis, we illustrate that the basic nature of flow reversals in convecting fluids can depend on the dimensionless parameters describing the system. Specifically, we find evidence of low-dimensional behavior in flow reversals occurring at zero Prandtl number, whereas we fail to find such signatures for reversals at infinite Prandtl number. Thus, even in a single system, as one varies the system parameters, one can encounter reversals that are fundamentally different in nature. Consequently, we conclude that a single general low-dimensional deterministic model cannot faithfully characterize flow reversals for every set of parameter values.

POD analysis of the instability mode of a low-speed streak in a laminar boundary layer

NASA Astrophysics Data System (ADS)

Deng, Si-Chao; Pan, Chong; Wang, Jin-Jun; Rinoshika, Akira

2017-12-01

The instability of one single low-speed streak in a zero-pressure-gradient laminar boundary layer is investigated experimentally via both hydrogen bubble visualization and planar particle image velocimetry (PIV) measurement. A single low-speed streak is generated and destabilized by the wake of an interference wire positioned normal to the wall and in the upstream. The downstream development of the streak includes secondary instability and self-reproduction process, which leads to the generation of two additional streaks appearing on either side of the primary one. A proper orthogonal decomposition (POD) analysis of PIV measured velocity field is used to identify the components of the streak instability in the POD mode space: for a sinuous/varicose type of POD mode, its basis functions present anti-symmetric/symmetric distributions about the streak centerline in the streamwise component, and the symmetry condition reverses in the spanwise component. It is further shown that sinuous mode dominates the turbulent kinematic energy (TKE) through the whole streak evolution process, the TKE content first increases along the streamwise direction to a saturation value and then decays slowly. In contrast, varicose mode exhibits a sustained growth of the TKE content, suggesting an increasing competition of varicose instability against sinuous instability.

Time Reversal Mirrors and Cross Correlation Functions in Acoustic Wave Propagation

NASA Astrophysics Data System (ADS)

Fishman, Louis; Jonsson, B. Lars G.; de Hoop, Maarten V.

2009-03-01

In time reversal acoustics (TRA), a signal is recorded by an array of transducers, time reversed, and then retransmitted into the configuration. The retransmitted signal propagates back through the same medium and retrofocuses on the source that generated the signal. If the transducer array is a single, planar (flat) surface, then this configuration is referred to as a planar, one-sided, time reversal mirror (TRM). In signal processing, for example, in active-source seismic interferometry, the measurement of the wave field at two distinct receivers, generated by a common source, is considered. Cross correlating these two observations and integrating the result over the sources yield the cross correlation function (CCF). Adopting the TRM experiments as the basic starting point and identifying the kinematically correct correspondences, it is established that the associated CCF signal processing constructions follow in a specific, infinite recording time limit. This perspective also provides for a natural rationale for selecting the Green's function components in the TRM and CCF expressions. For a planar, one-sided, TRM experiment and the corresponding CCF signal processing construction, in a three-dimensional homogeneous medium, the exact expressions are explicitly calculated, and the connecting limiting relationship verified. Finally, the TRM and CCF results are understood in terms of the underlying, governing, two-way wave equation, its corresponding time reversal invariance (TRI) symmetry, and the absence of TRI symmetry in the associated one-way wave equations, highlighting the role played by the evanescent modal contributions.

The role of single-shot metronidazole in the prevention of Clostridium difficile infection following ileostomy reversal surgery.

PubMed

Fernandes, Roland; Robinson, Paul; Rangarajan, Karan; Scott, Sophie; Angco, Laura

2017-05-01

Symptomatic infection with Clostridium difficile is strongly linked to antibiotic use and rates are higher for colorectal surgery. In February 2015, trust policy for antibiotic prophylaxis of ileostomy reversal surgery was changed from three doses of metronidazole plus cefuroxime to single-dose metronidazole, in a bid to reduce rates of Clostridium difficile infection. A retrospective cohort study was conducted at a single, large hospital trust between February 2014 and February 2016, before and after change in antimicrobial policy. Theatre data, clinical notes and pathology results were all reviewed. Outcome data, patient age, gender, length of operation and hospital stay were extracted. One hundred three patients underwent ileostomy reversal surgery between February 2014 and February 2015. All received cefuroxime together with metronidazole at induction of anaesthesia followed by two further post-operative doses as operative prophylaxis. Ninety-six patients underwent ileostomy reversal surgery between February 2015 and February 2016. All received single-dose metronidazole at induction as prophylaxis. Post-operative diarrhoea was significantly reduced in patients given single-dose metronidazole compared with patients managed with multiple dose, dual antibiotic therapy (32 vs 12.5%, P 0.001). Rates of CDI were also significantly reduced in patients given single-dose metronidazole (6.8 vs 1%, P 0.038). Single-dose, pre-operative metronidazole is effective at reducing post-operative diarrhoea and CDI in ileostomy reversal surgery compared with multiple-dose cefuroxime plus metronidazole. Metronidazole may be effective as a prophylactic antibiotic against CDI in colonic surgery.

Simulation study of a chaotic cavity transducer based virtual phased array used for focusing in the bulk of a solid material.

PubMed

Delrue, Steven; Van Den Abeele, Koen; Bou Matar, Olivier

2016-04-01

In acoustic and ultrasonic non-destructive testing techniques, it is sometimes beneficial to concentrate sound energy at a chosen location in space and at a specific instance in time, for example to improve the signal-to-noise ratio or activate the nonlinearity of damage features. Time Reversal (TR) techniques, taking advantage of the reversible character of the wave equation, are particularly suited to focus ultrasonic waves in time and space. The characteristics of the energy focusing in solid media using principles of time reversed acoustics are highly influenced by the nature and dimensions of the medium, the number of transducers and the length of the received signals. Usually, a large number of transducers enclosing the domain of interest is needed to improve the quality of the focusing. However, in the case of highly reverberant media, the number of transducers can be reduced to only one (single-channel TR). For focusing in a non-reverberant medium, which is impossible when using only one source, an adaptation of the single-channel reciprocal TR procedure has been recently suggested by means of a Chaotic Cavity Transducer (CCT), a single element transducer glued on a cavity of chaotic shape. In this paper, a CCT is used to focus elastic energy, at different times, in different points along a predefined line on the upper surface of a thick solid sample. Doing so, all focusing points can act as a virtual phased array transducer, allowing to focus in any point along the depth direction of the sample. This is impossible using conventional reciprocal TR, as you need to have access to all points in the bulk of the material for detecting signals to be used in the TR process. To asses and provide a better understanding of this concept, a numerical study has been developed, allowing to verify the basic concepts of the virtual phased array and to illustrate multi-component time reversal focusing in the bulk of a solid material. Copyright © 2016 Elsevier B.V. All rights reserved.

Joint Kinetics and Kinematics During Common Lower Limb Rehabilitation Exercises

PubMed Central

Comfort, Paul; Jones, Paul Anthony; Smith, Laura Constance; Herrington, Lee

2015-01-01

Context  Unilateral body-weight exercises are commonly used to strengthen the lower limbs during rehabilitation after injury, but data comparing the loading of the limbs during these tasks are limited. Objective  To compare joint kinetics and kinematics during 3 commonly used rehabilitation exercises. Design  Descriptive laboratory study. Setting  Laboratory. Patients or Other Participants  A total of 9 men (age = 22.1 ± 1.3 years, height = 1.76 ± 0.08 m, mass = 80.1 ± 12.2 kg) participated. Intervention(s)  Participants performed the single-legged squat, forward lunge, and reverse lunge with kinetic data captured via 2 force plates and 3-dimensional kinematic data collected using a motion-capture system. Main Outcome Measure(s)  Peak ground reaction forces, maximum joint angles, and peak sagittal-joint moments. Results  We observed greater eccentric and concentric peak vertical ground reaction forces during the single-legged squat than during both lunge variations (P ≤ .001). Both lunge variations demonstrated greater knee and hip angles than did the single-legged squat (P < .001), but we observed no differences between lunges (P > .05). Greater dorsiflexion occurred during the single-legged squat than during both lunge variations (P < .05), but we noted no differences between lunge variations (P = .70). Hip-joint moments were greater during the forward lunge than during the reverse lunge (P = .003) and the single-legged squat (P = .011). Knee-joint moments were greater in the single-legged squat than in the reverse lunge (P < .001) but not greater in the single-legged squat than in the forward lunge (P = .41). Ankle-joint moments were greater during the single-legged squat than during the forward lunge (P = .002) and reverse lunge (P < .001). Conclusions  Appropriate loading progressions for the hip should begin with the single-legged squat and progress to the reverse lunge and then the forward lunge. In contrast, loading progressions for the knee and ankle should begin with the reverse lunge and progress to the forward lunge and then the single-legged squat. PMID:26418958

Reverse Algols

NASA Technical Reports Server (NTRS)

Leung, K. C.

1989-01-01

Reverse Algols, binary systems with a semidetached configuration in which the more massive component is in contact with the critical equipotential surface, are examined. Observational evidence for reverse Algols is presented and the parameters of seven reverse Algols are listed. The evolution of Algols and reverse Algols is discussed. It is suggested that, because reverse Algols represent the premass-reversal semidetached phase of close binary evolution, the evolutionary time scale between regular and reverse Algols is the ratio of the number of confirmed systems of these two Algol types.

Use of a shorter humeral stem in revision reverse shoulder arthroplasty.

PubMed

Wagner, Eric R; Statz, Joseph M; Houdek, Matthew T; Cofield, Robert H; Sánchez-Sotelo, Joaquín; Sperling, John W

2017-08-01

The purpose of this study was to examine the outcomes of revision reverse arthroplasty using short bone-preserving humeral components in revising a long-stemmed component. During a 7-year period, 39 patients who underwent revision reverse shoulder arthroplasty using the long to short humeral component technique were included. The mean age was 72 years. Prior implants used in the primary setting included anatomic (n = 26), hemiarthroplasty (n = 11), and reverse (n = 2). At a follow-up of 3 years (2-5), 5 shoulders (13%) required revision surgery, including 1 for a periprosthetic humerus fracture and 4 for glenoid component loosening. The survival free of revision for any reason and revision for humeral disease was 84% and 94%, respectively. One patient experienced a nondisplaced greater tuberosity fracture at 18 months postoperatively that healed without operative intervention. There were no dislocations or infections. Overall, patients experienced excellent overall improvements in their pain levels and shoulder motion (P < .001), with a postoperative 91% satisfaction rate as well as postoperative American Shoulder and Elbow Surgeons score of 68 and Simple Shoulder Test score of 6.7. At most recent radiographic follow-up, 1 (5%) patient had grade 3 humeral lucency. Preserving bone stock through conversion to a shorter reverse humeral stem in the revision setting is a reasonable option with good short- to intermediate-term results and low rates of humeral complications. Using the shorter stem components provides adequate stability and high rates of humeral component ingrowth. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Specific effects of a calorie-based intervention on stair climbing in overweight commuters.

PubMed

Lewis, Amanda L; Eves, Frank F

2011-10-01

Point-of-choice prompts consistently increase stair climbing; a greater increase in overweight than normal weight individuals was reported in a multi-component worksite campaign. The purpose of this study is to investigate effects of a multi-component campaign, on stair climbing, in a public access setting. In an interrupted-time-series-design, baseline observations (2 weeks) preceded a 2-week point-of-choice prompt. An additional message, positioned at the top of the climb for a further 6-week period, summarised the calorific consequences of a single ascent. Inconspicuous observers recorded traveller's methods of ascent, coded by sex and weight status, twice a week between 08:00 and 09:59. At baseline, the overweight chose stairs less than normal weight individuals. The multi-component campaign targeting weight control reversed this bias, increasing stair climbing only in overweight individuals. The specificity of the effect confirms the appeal of this lifestyle activity for the overweight. The discussion focuses on how intentions to control weight may be converted into behaviour.

Identification of salivary components that induce transition of hyphae to yeast in Candida albicans.

PubMed

Leito, Jelani T D; Ligtenberg, Antoon J M; Nazmi, Kamran; Veerman, Enno C I

2009-10-01

Candida albicans, the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 degrees C under aerobic conditions with 5% CO(2). Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis.

Ultraviolet light-responsive photorheological fluids: as a new class of smart fluids

NASA Astrophysics Data System (ADS)

Cho, Min-Young; Kim, Ji-Sik; Choi, Hyoung Jin; Choi, Seung-Bok; Kim, Gi-Woo

2017-05-01

We present a comprehensive introduction to the photorheological (PR) fluids whose rheological behavior can be changed by ultraviolet (UV) light with a wavelength of 365 nm. When the PR fluid was exposed to UV light, the viscosity of the fluid decreased, while the viscosity recovered to its initial value when UV light was turned off, indicating that the viscosity of these types of fluids can be reversible and tunable by UV light. Contrary to conventional smart fluids, such as electrorheological and magnetorheological fluids, PR fluid does not suffer from a phase splitting problem because it exists in a single-phase solution. Additionally, the PR fluid does not require any contact component, such as electrodes, and electric wires that are essential components for conventional smart fluids. In this work, the PR fluids were synthesized by doping lecithin/sodium deoxycholate reverse micelles with a photo-chromic spiropyran compound. It is demonstrated that the viscosity changes of PR fluids can be induced by UV light, and their rheological properties are examined in detail. In addition, an example of tailoring rheological properties using photoluminescence was introduced for improved response time. One of the potential applications, such as microfluidic flow control using the PR fluids, is also briefly presented.

Damping of collective modes and the echo effect in a confined Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Kuklov, A. B.; Chencinski, N.

1998-04-01

We discuss the reversible nature of two mechanisms of the apparent damping of the collective modes of a confined Bose-Einstein condensate -- Landau Damping (LD) and a dephasing caused by thermal fluctuations of the normal component. The reversibility of the damping in both cases can be tested by the echo effect, when two consecutive external pulses modulate the potential trapping the condensate and induce a third pulse -- the echo -- at the time approximately equal to twice the time interval between the first two pulses. This effect is similar to the phonon echo in powders (Koji Kajimura in Physical Acoustics), ed. W.P. Mason, V.XVI, Academic Press, NY, Toronto 1982.. Parameters of the echo for the isotropic condensate are calculated analytically in the adiabatic approximation for the case of the small external pulses. Numerical simulations for the arbitrary pulses are also presented. The echo in an anisotropic condensate, where the adaibatic approximation is not valid because of the LD, is described in terms of the model of a single oscillator interacting with a quasi-continuum of modes which constitutes the normal component. In both cases in the weak echo limit the echo amplitude turns out to be proportional to the amplitudes of the external pulses. We suggest to test these predictions experimentally.

A "reverse direction" technique of single-port left upper pulmonary resection.

PubMed

Zhang, Min; Sihoe, Alan D L; Du, Ming

2016-08-01

Single-port video-assisted thoracoscopic surgery (VATS) left upper lobectomy is difficult amongst all the lobes. At the beginning of single-port lobectomies, the upper lobes were believed not to be amenable for single-port approach due to the difficult angulation for staplers. Gonzalez reported the first single-port VATS left upper lobectomy in 2011. We report a new technique of single-port VATS left upper lobectomy with the concept of "reverse direction". We divide the apical-anterior arterial trunk with upper vein in the last. The procedure sequence is described as follows: posterior artery, lingular artery, bronchus and finally upper vein & apical-anterior arterial trunk. This method could overcome the angular limitations frequently encountered in single-port VATS procedures; reduce the risk of injuries to pulmonary artery; broaden the indications of single-port the upper lobe of the left lung (LUL) to include hypoplastic lung fissures. Limitations of this new practice include the enlargement or severe calcifications of hilar and bronchial lymph nodes. A "reverse direction" technique of single-port left upper pulmonary resection is feasible and safe.

Age of the Xalnene Ash, Central Mexico and Archeological Implications

NASA Astrophysics Data System (ADS)

Renne, P. R.; Feinberg, J. M.; Waters, M. R.; Cabrales, J. A.; Castillo, P. O.; Campa, M. P.; Knight, K. B.

2005-12-01

Human footprints ~40 ka old have been reported from the Toloquilla quarry near Valsequillo Reservoir, ca. 15 km south of the city of Puebla in central Mexico (http://www.mexicanfootprints.co.uk/default.htm). If correct, this would be important evidence for early peopling of the Americas. The indentations interpreted as footprints and other ichnofossils occur on the surface of an indurated basaltic lapilli tuff within a several meter thick sequence of thinly bedded (1-10 cm) tuffs of similar character, lacking paleosols, erosional features or interlayered sediments, informally known as the Xalnene ash. A sample was collected at 18°55.402` N latitude and 098°09.375` W longitude from the surface on which the purported footprints occur. Lapilli were separated and analyzed by incremental heating 40Ar/39Ar methods, yielding 9 indistinguishable plateau ages averaging 1.30 ±0.03 Ma (2σ) for single lapilli (N=6) and multiple lapilli (N=3) subsamples. Though some minor discordance (presumably due to 39Ar recoil) is manifest in 5 of the age spectra, all plateaux comprise >60% of the 39Ar released and 4 or more consecutive steps. Paleomagnetic data from azimuthally unoriented bulk samples of 11.25 cm3 reveal a reverse polarity (I = -32.1°) thermoremanent component carried by titanomagnetite and a normal polarity component carried by goethite. Measurements on individual matrix-free lapilli lack the goethite component, which is presumed to be associated with the clay-rich cement. Consistency of the reverse component implies deposition of the lapilli at supra-Curie temperatures, with no postdepositional reworking. Reverse polarity is consistent with deposition during chron C1r.2r (1.77 to 1.07 Ma) as indicated by the 40Ar/39Ar data. If the features observed on the tuff are indeed footprints, their 1.3 Ma antiquity would be truly remarkable, predating by far any other evidence for human presence in the Americas and in fact predating the evolutionary emergence of Homo sapiens (in Africa) by more than 1 Ma. We conclude that the identification of these features as syn-depositional human footprints is likely erroneous.

The Application of Strain Range Partitioning Method to Torsional Creep-Fatigue Interaction

NASA Technical Reports Server (NTRS)

Zamrik, S. Y.

1975-01-01

The method of strain range partitioning was applied to a series of torsional fatigue tests conducted on tubular 304 stainless steel specimens at 1200 F. Creep strain was superimposed on cycling strain, and the resulting strain range was partitioned into four components; completely reversed plastic shear strain, plastic shear strain followed by creep strain, creep strain followed by plastic strain and completely reversed creep strain. Each strain component was related to the cyclic life of the material. The damaging effects of the individual strain components were expressed by a linear life fraction rule. The plastic shear strain component showed the least detrimental factor when compared to creep strain reversed by plastic strain. In the latter case, a reduction of torsional fatigue life in the order of magnitude of 1.5 was observed.

Reversible conversion of valence-tautomeric copper metal-organic frameworks dependent single-crystal-to-single-crystal oxidation/reduction: a redox-switchable catalyst for C-H bonds activation reaction.

PubMed

Huang, Chao; Wu, Jie; Song, Chuanjun; Ding, Ran; Qiao, Yan; Hou, Hongwei; Chang, Junbiao; Fan, Yaoting

2015-06-28

Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like Cu(I) framework and a topologically equivalent neutral Cu(I)Cu(II) mixed-valent framework. The unique conversion behavior of the Cu(I) framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C-H bonds.

An Evaluation of the Social Support Component of Simplified Habit Reversal

ERIC Educational Resources Information Center

Flessner, Christopher A.; Miltenberger, Raymond G.; Egemo, Kristin; Kelso, Pam; Jostad, Candice; Johnson, Brigitte; Gatheridge, Brian J.; Neighbors, Clayton

2005-01-01

This study examined the role that the social support component of simplified habit reversal (SHR) plays in the treatment of body-focused repetitive behavior disorders (nail biting) in college-aged individuals. This study compared 2 versions of the SHR procedure, the first consisting of awareness training, competing response training, and social…

The magnetic polarity stratigraphy of the Mauch Chunk Formation, Pennsylvania

PubMed Central

Opdyke, Neil D.; DiVenere, Victor J.

2004-01-01

Three sections of Chesterian Mauch Chunk Formation in Pennsylvania have been studied paleomagnetically to determine a Late Mississippian magnetic polarity stratigraphy. The upper section at Lavelle includes a conglomerate with abundant red siltstone rip-up clasts that yielded a positive conglomerate test. All samples were subjected to progressive thermal demagnetization to temperatures as high as 700°C. Two components of magnetization were isolated: a synfolding “B” component and the prefolding “C” component. The conglomerate test is positive, indicating that the C component was acquired very early in the history of the sediment. A coherent pattern of magnetic polarity reversals was identified. Five magnetozones were identified in the upper Lavelle section, which yields a pattern that is an excellent match with the pattern of reversals obtained from the upper Mauch Chunk at the original type section of the Mississippian/Pennsylvanian boundary at Pottsville, PA. The frequency of reversals in the upper Mississippian, as identified in the Mauch Chunk Formation, is approximately one to two per million years, which is an average for field reversal through time. PMID:15353597

The magnetic polarity stratigraphy of the Mauch Chunk Formation, Pennsylvania.

PubMed

Opdyke, Neil D; DiVenere, Victor J

2004-09-14

Three sections of Chesterian Mauch Chunk Formation in Pennsylvania have been studied paleomagnetically to determine a Late Mississippian magnetic polarity stratigraphy. The upper section at Lavelle includes a conglomerate with abundant red siltstone rip-up clasts that yielded a positive conglomerate test. All samples were subjected to progressive thermal demagnetization to temperatures as high as 700 degrees C. Two components of magnetization were isolated: a synfolding "B" component and the prefolding "C" component. The conglomerate test is positive, indicating that the C component was acquired very early in the history of the sediment. A coherent pattern of magnetic polarity reversals was identified. Five magnetozones were identified in the upper Lavelle section, which yields a pattern that is an excellent match with the pattern of reversals obtained from the upper Mauch Chunk at the original type section of the Mississippian/Pennsylvanian boundary at Pottsville, PA. The frequency of reversals in the upper Mississippian, as identified in the Mauch Chunk Formation, is approximately one to two per million years, which is an average for field reversal through time.

Static internal performance of single expansion-ramp nozzles with thrust vectoring and reversing

NASA Technical Reports Server (NTRS)

Re, R. J.; Berrier, B. L.

1982-01-01

The effects of geometric design parameters on the internal performance of nonaxisymmetric single expansion-ramp nozzles were investigated at nozzle pressure ratios up to approximately 10. Forward-flight (cruise), vectored-thrust, and reversed-thrust nozzle operating modes were investigated.

Simultaneous quantification of alternatively spliced transcripts in a single droplet digital PCR reaction.

PubMed

Sun, Bing; Tao, Lian; Zheng, Yun-Ling

2014-06-01

Human telomerase reverse transcriptase (hTERT) is an essential component required for telomerase activity and telomere maintenance. Several alternatively spliced forms of hTERT mRNA have been reported in human primary and tumor cells. Currently, however, there is no sensitive and accurate method for the simultaneous quantification of multiple alternatively spliced RNA transcripts, such as in the case of hTERT. Here we show droplet digital PCR (ddPCR) provides sensitive, simultaneous digital quantification in a single reaction of two alternatively spliced single deletion hTERT transcripts (α-/β+ and α+/β-) as well as the opportunity to manually quantify non-deletion (α+/β+) and double deletion (α-/β-) transcripts. Our ddPCR method enables direct comparison among four alternatively spliced mRNAs without the need for internal standards or multiple primer pairs specific for each variant as real-time PCR (qPCR) requires, thus eliminating potential variation due to differences in PCR amplification efficiency.

Magnetic stray-field studies of a single Cobalt nanoelement as a component of the building blocks of artificial square spin ice

NASA Astrophysics Data System (ADS)

Pohlit, Merlin; Porrati, Fabrizio; Huth, Michael; Ohno, Yuzo; Ohno, Hideo; Müller, Jens

2016-02-01

We use Focused Electron Beam Deposition (FEBID) to directly write Cobalt magnetic nanoelements onto a micro-Hall magnetometer, which allows for high-sensitivity measurements of the magnetic stray field emanating from the samples. In a previous study [M. Pohlit et al., J. Appl. Phys. 117 (2015) 17C746] [21] we investigated thermal dynamics of an individual building block (nanocluster) of artificial square spin ice. In this work, we compare the results of this structure with interacting elements to the switching of a single nanoisland. By analyzing the survival function of the repeatedly prepared state in a given temperature range, we find thermally activated switching dynamics. A detailed analysis of the hysteresis loop reveals a metastable microstate preceding the overall magnetization reversal of the single nanoelement, also found in micromagnetic simulations. Such internal degrees of freedom may need to be considered, when analyzing the thermal dynamics of larger spin ice configurations on different lattice types.

Preliminary design for a reverse Brayton cycle cryogenic cooler

NASA Technical Reports Server (NTRS)

Swift, Walter L.

1993-01-01

A long life, single stage, reverse Brayton cycle cryogenic cooler is being developed for applications in space. The system is designed to provide 5 W of cooling at a temperature of 65 Kelvin with a total cycle input power of less than 200 watts. Key features of the approach include high speed, miniature turbomachines; an all metal, high performance, compact heat exchanger; and a simple, high frequency, three phase motor drive. In Phase 1, a preliminary design of the system was performed. Analyses and trade studies were used to establish the thermodynamic performance of the system and the performance specifications for individual components. Key mechanical features for components were defined and assembly layouts for the components and the system were prepared. Critical materials and processes were identified. Component and brassboard system level tests were conducted at cryogenic temperatures. The system met the cooling requirement of 5 W at 65 K. The system was also operated over a range of cooling loads from 0.5 W at 37 K to 10 W at 65 K. Input power to the system was higher than target values. The heat exchanger and inverter met or exceeded their respective performance targets. The compresssor/motor assembly was marginally below its performance target. The turboexpander met its aerodynamic efficiency target, but overall performance was below target because of excessive heat leak. The heat leak will be reduced to an acceptable value in the engineering model. The results of Phase 1 indicate that the 200 watt input power requirement can be met with state-of-the-art technology in a system which has very flexible integration requirements and negligible vibration levels.

Preliminary design for a reverse Brayton cycle cryogenic cooler

NASA Astrophysics Data System (ADS)

Swift, Walter L.

1993-12-01

A long life, single stage, reverse Brayton cycle cryogenic cooler is being developed for applications in space. The system is designed to provide 5 W of cooling at a temperature of 65 Kelvin with a total cycle input power of less than 200 watts. Key features of the approach include high speed, miniature turbomachines; an all metal, high performance, compact heat exchanger; and a simple, high frequency, three phase motor drive. In Phase 1, a preliminary design of the system was performed. Analyses and trade studies were used to establish the thermodynamic performance of the system and the performance specifications for individual components. Key mechanical features for components were defined and assembly layouts for the components and the system were prepared. Critical materials and processes were identified. Component and brassboard system level tests were conducted at cryogenic temperatures. The system met the cooling requirement of 5 W at 65 K. The system was also operated over a range of cooling loads from 0.5 W at 37 K to 10 W at 65 K. Input power to the system was higher than target values. The heat exchanger and inverter met or exceeded their respective performance targets. The compresssor/motor assembly was marginally below its performance target. The turboexpander met its aerodynamic efficiency target, but overall performance was below target because of excessive heat leak. The heat leak will be reduced to an acceptable value in the engineering model. The results of Phase 1 indicate that the 200 watt input power requirement can be met with state-of-the-art technology in a system which has very flexible integration requirements and negligible vibration levels.

A Paleomagnetic and Paleointensity Study on Late Pliocene Volcanic Rocks From Southern Georgia (Caucasus)

NASA Astrophysics Data System (ADS)

Calvo-Rathert, M.; Bogalo, M.; Gogichaishvili, A.; Vegas-Tubia, N.; Sologashvili, J.; Villalain, J.

2009-05-01

A paleomagnetic, rock-magnetic and paleointensity study was carried out on 21 basaltic lava flows belonging to four different sequences of late Pliocene age from southern Georgia (Caucasus): Diliska (5 flows), Kvemo Orozmani (5 flows), Dmanisi (11 flows) and Zemo Karabulaki (3 flows). Paleomagnetic analysis generally showed the presence of a single component (mainly in the Dmanisi sequence) but also two more or less superimposed components in several other cases. All sites except one clearly displayed a normal-polarity characteristic component. Susceptibility-versus-temperature curves measured in argon atmosphere on whole- rock powdered samples yielded low-Ti titanomagnetite as main carrier of remanence, although a lower Tc- component (300-400C) was also observed in several cases. Both reversible and non-reversible k-T curves were measured. A pilot paleointensity study was performed with the Coe method on two samples of each of those sites considered suitable after interpretation of rock-magnetic and paleomagnetic results. The pilot study showed that reliable paleointensity results were mainly obtained from sites of the Dmanisi sequence. This thick sequence of basaltic lava flows records the upper end of the normal-polarity Olduvai subchron, a fact confirmed by 40Ar/39Ar dating of the uppermost lava flow and overlying volcanogenic ashes, which yields ages of 1.8 to 1.85 My. A new paleointensity experiment was carried out only on samples belonging to the Dmanisi sequence. Although this work is still in progress, first results show that paleointensities are low, their values lying between 10 and 20 µT in many cases, and not being higher than 30 µT. For comparison, present day field is 47 µT.

Reversible Thermoset Adhesives

NASA Technical Reports Server (NTRS)

Mac Murray, Benjamin C. (Inventor); Tong, Tat H. (Inventor); Hreha, Richard D. (Inventor)

2016-01-01

Embodiments of a reversible thermoset adhesive formed by incorporating thermally-reversible cross-linking units and a method for making the reversible thermoset adhesive are provided. One approach to formulating reversible thermoset adhesives includes incorporating dienes, such as furans, and dienophiles, such as maleimides, into a polymer network as reversible covalent cross-links using Diels Alder cross-link formation between the diene and dienophile. The chemical components may be selected based on their compatibility with adhesive chemistry as well as their ability to undergo controlled, reversible cross-linking chemistry.

Single Cell Total RNA Sequencing through Isothermal Amplification in Picoliter-Droplet Emulsion.

PubMed

Fu, Yusi; Chen, He; Liu, Lu; Huang, Yanyi

2016-11-15

Prevalent single cell RNA amplification and sequencing chemistries mainly focus on polyadenylated RNAs in eukaryotic cells by using oligo(dT) primers for reverse transcription. We develop a new RNA amplification method, "easier-seq", to reverse transcribe and amplify the total RNAs, both with and without polyadenylate tails, from a single cell for transcriptome sequencing with high efficiency, reproducibility, and accuracy. By distributing the reverse transcribed cDNA molecules into 1.5 × 10 5 aqueous droplets in oil, the cDNAs are isothermally amplified using random primers in each of these 65-pL reactors separately. This new method greatly improves the ease of single-cell RNA sequencing by reducing the experimental steps. Meanwhile, with less chance to induce errors, this method can easily maintain the quality of single-cell sequencing. In addition, this polyadenylate-tail-independent method can be seamlessly applied to prokaryotic cell RNA sequencing.

An Active Broad Area Cooling Model of a Cryogenic Propellant Tank with a Single Stage Reverse Turbo-Brayton Cycle Cryocooler

NASA Technical Reports Server (NTRS)

Guzik, Monica C.; Tomsik, Thomas M.

2011-01-01

As focus shifts towards long-duration space exploration missions, an increased interest in active thermal control of cryogenic propellants to achieve zero boil-off of cryogens has emerged. An active thermal control concept of considerable merit is the integration of a broad area cooling system for a cryogenic propellant tank with a combined cryocooler and circulator system that can be used to reduce or even eliminate liquid cryogen boil-off. One prospective cryocooler and circulator combination is the reverse turbo-Brayton cycle cryocooler. This system is unique in that it has the ability to both cool and circulate the coolant gas efficiently in the same loop as the broad area cooling lines, allowing for a single cooling gas loop, with the primary heat rejection occurring by way of a radiator and/or aftercooler. Currently few modeling tools exist that can size and characterize an integrated reverse turbo-Brayton cycle cryocooler in combination with a broad area cooling design. This paper addresses efforts to create such a tool to assist in gaining a broader understanding of these systems, and investigate their performance in potential space missions. The model uses conventional engineering and thermodynamic relationships to predict the preliminary design parameters, including input power requirements, pressure drops, flow rate, cycle performance, cooling lift, broad area cooler line sizing, and component operating temperatures and pressures given the cooling load operating temperature, heat rejection temperature, compressor inlet pressure, compressor rotational speed, and cryogenic tank geometry. In addition, the model allows for the preliminary design analysis of the broad area cooling tubing, to determine the effect of tube sizing on the reverse turbo-Brayton cycle system performance. At the time this paper was written, the model was verified to match existing theoretical documentation within a reasonable margin. While further experimental data is needed for full validation, this tool has already made significant steps towards giving a clearer understanding of the performance of a reverse turbo-Brayton cycle cryocooler integrated with broad area cooling technology for zero boil-off active thermal control.

Testing a generalized domain model of photodegradation and self-healing using novel optical characterization techniques and the effects of an applied electric field

NASA Astrophysics Data System (ADS)

Anderson, Benjamin R.

Reversible photodegradation is a relatively new phenomenon which is not well understood. Previous research into the phenomenon has focused primarily on non-linear measurements such as amplified spontaneous emission(ASE) and two-photon fluorescence(TPF). We expand on this research by considering linear optical mea- surements, such as transmittance imaging and absorption spectroscopy, of disperse orange 11(DO11) dye-doped (poly)methyl-methacralate(PMMA) thin films and find photodegradation to contain both a reversible component and irreversible component, with the irreversible component having a small nonlinear susceptibility. From absorption measurements, and the small nonlinear susceptibility of the irreversible component, we hypothesize that the reversible component corresponds to damage to the dye, and the irreversible component is due to damage to the polymer host. Also, we develop models of depth dependent photodegradation taking pump beam absorption and propagation into account. We find that pump absorption must be taken into account, and that ignoring the effect leads to an underestimation of the true decay rate and degree of damage. In addition, we find pump propagation effects occur on large length scales, such that they are negligible when compared to absorption and typical sample thicknesses. Finally, we perform electric field dependent reversible photodegradation measurements and find that the underlying mechanism of reversible photodegradation is sensitive to the dye-doped polymer's electrical properties. We develop an extension to the correlated chromophore domain model to include the effect of an applied field, and find the model to fit experimental data for varying intensity, temperature, and applied electric field with only one set of model parameters.

Mean velocities and Reynolds stresses upstream of a simulated wing-fuselage juncture

NASA Technical Reports Server (NTRS)

Mcmahon, H.; Hubbartt, J.; Kubendran, L. R.

1983-01-01

Values of three mean velocity components and six turbulence stresses measured in a turbulent shear layer upstream of a simulated wing-fuselage juncture and immediately downstream of the start of the juncture are presented nd discussed. Two single-sensor hot-wire probes were used in the measurements. The separated region just upstream of the wing contains an area of reversed flow near the fuselage surface where the turbulence level is high. Outside of this area the flow skews as it passes around the body, and in this skewed region the magnitude and distribution of the turbulent normal and shear stresses within the shear layer are modified slightly by the skewing and deceleration of the flow. A short distance downstream of the wing leading edge the secondary flow vortext is tightly rolled up and redistributes both mean flow and turbulence in the juncture. The data acquisition technique employed here allows a hot wire to be used in a reversed flow region to indicate flow direction.

Virus fitness differences observed between two naturally occurring isolates of Ebola virus Makona variant using a reverse genetics approach.

PubMed

Albariño, César G; Guerrero, Lisa Wiggleton; Chakrabarti, Ayan K; Kainulainen, Markus H; Whitmer, Shannon L M; Welch, Stephen R; Nichol, Stuart T

2016-09-01

During the large outbreak of Ebola virus disease that occurred in Western Africa from late 2013 to early 2016, several hundred Ebola virus (EBOV) genomes have been sequenced and the virus genetic drift analyzed. In a previous report, we described an efficient reverse genetics system designed to generate recombinant EBOV based on a Makona variant isolate obtained in 2014. Using this system, we characterized the replication and fitness of 2 isolates of the Makona variant. These virus isolates are nearly identical at the genetic level, but have single amino acid differences in the VP30 and L proteins. The potential effects of these differences were tested using minigenomes and recombinant viruses. The results obtained with this approach are consistent with the role of VP30 and L as components of the EBOV RNA replication machinery. Moreover, the 2 isolates exhibited clear fitness differences in competitive growth assays. Published by Elsevier Inc.

Evidence for Two Separate Heliospheric Current Sheets of Cylindrical Shape During Mid-2012

NASA Astrophysics Data System (ADS)

Wang, Y.-M.; Young, P. R.; Muglach, K.

2014-01-01

During the reversal of the Sun's polar fields at sunspot maximum, outward extrapolations of magnetograph measurements often predict the presence of two or more current sheets extending into the interplanetary medium, instead of the single heliospheric current sheet (HCS) that forms the basis of the standard "ballerina skirt" picture. By comparing potential-field source-surface models of the coronal streamer belt with white-light coronagraph observations, we deduce that the HCS was split into two distinct structures with circular cross sections during mid-2012. These cylindrical current sheets were centered near the heliographic equator and separated in longitude by roughly 180° a corresponding four-sector polarity pattern was observed at Earth. Each cylinder enclosed a negative-polarity coronal hole that was identifiable in extreme ultraviolet images and gave rise to a high-speed stream. The two current sheet systems are shown to be a result of the dominance of the Sun's nonaxisymmetric quadrupole component, as the axial dipole field was undergoing its reversal during solar cycle 24.

Evidence for Two Separate Heliospheric Current Sheets of Cylindrical Shape During Mid-2012

NASA Technical Reports Server (NTRS)

Wang, Y.-M.; Young, P. R.; Muglach, K.

2013-01-01

During the reversal of the Sun's polar fields at sunspot maximum, outward extrapolations of magnetograph measurements often predict the presence of two or more current sheets extending into the interplanetary medium, instead of the single heliospheric current sheet (HCS) that forms the basis of the standard 'ballerina skirt' picture. By comparing potential-field source-surface models of the coronal streamer belt with white-light coronagraph observations, we deduce that the HCS was split into two distinct structures with circular cross sections during mid-2012. These cylindrical current sheets were centered near the heliographic equator and separated in longitude by roughly 180 deg; a corresponding four-sector polarity pattern was observed at Earth. Each cylinder enclosed a negative-polarity coronal hole that was identifiable in extreme ultraviolet images and gave rise to a high-speed stream. The two current sheet systems are shown to be a result of the dominance of the Sun's nonaxisymmetric quadrupole component, as the axial dipole field was undergoing its reversal during solar cycle 24.

Biomechanical comparison of component position and hardware failure in the reverse shoulder prosthesis.

PubMed

Gutiérrez, Sergio; Greiwe, R Michael; Frankle, Mark A; Siegal, Steven; Lee, William E

2007-01-01

There has been renewed interest in reverse shoulder arthroplasty for the treatment of glenohumeral arthritis with concomitant rotator cuff deficiency. Failure of the prosthesis at the glenoid attachment site remains a concern. The purpose of this study was to examine glenoid component stability with regard to the angle of implantation. This investigation entailed a biomechanical analysis to evaluate forces and micromotion in glenoid components attached to 12 polyurethane blocks at -15 degrees, 0 degrees, and +15 degrees of superior and inferior tilt. The 15 degrees inferior tilt had the most uniform compressive forces and the least amount of tensile forces and micromotion when compared with the 0 degrees and 15 degrees superiorly tilted baseplate. Our results suggest that implantation with an inferior tilt will reduce the incidence of mechanical failure of the glenoid component in a reverse shoulder prosthesis.

Paleo-Pole Positions from Martian Magnetic Anomaly Data

NASA Technical Reports Server (NTRS)

Taylor, Patrick T.; Frawley, James J.

2003-01-01

Magnetic component anomaly maps were made from five mapping cycles of the Mars Global Surveyor s magnetometer data. Our goal was to find and isolate positive and negative anomaly pairs which would indicate magnetization of a single source body. From these anomalies we could compute the direction of the magnetizing vector and subsequently the location of the magnetic pole existing at the time of magnetization. We found nine suitable anomaly pairs and from these we computed four North and 3 South poles with two at approximately 60 degrees north latitude. These results suggest that during the existence of the Martian main magnetic field it experienced several reversals.

Paleo-Pole Positions from Martian Magnetic Anomaly Data

NASA Technical Reports Server (NTRS)

Frawley, James J.; Taylor, Patrick T.

2004-01-01

Magnetic component anomaly maps were made from five mapping cycles of the Mars Global Surveyor's magnetometer data. Our goal was to find and isolate positive and negative anomaly pairs which would indicate magnetization of a single source body. From these anomalies we could compute the direction of the magnetizing vector and subsequently the location of the magnetic pole existing at the time of magnetization. We found nine suitable anomaly pairs and from these we computed paleo-poles that were nearly equally divided between north, south and mid-latitudes. These results suggest that during the existence of the martian main magnetic field it experienced several reversals and excursions.

A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids.

PubMed

Olsson, Petter; Holmbäck, Jan; Herslöf, Bengt

2014-11-21

This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30 min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection. Copyright © 2014 Elsevier B.V. All rights reserved.

Dynamic Multi-Component Covalent Assembly for the Reversible Binding of Secondary Alcohols and Chirality Sensing

PubMed Central

You, Lei; Berman, Jeffrey S.; Anslyn, Eric V.

2011-01-01

Reversible covalent bonding is often employed for the creation of novel supramolecular structures, multi-component assemblies, and sensing ensembles. In spite of remarkable success of dynamic covalent systems, the reversible binding of a mono-alcohol with high strength is challenging. Here we show that a strategy of carbonyl activation and hemiaminal ether stabilization can be embodied in a four-component reversible assembly that creates a tetradentate ligand and incorporates secondary alcohols with exceptionally high affinity. Evidence is presented that the intermediate leading to binding and exchange of alcohols is an iminium ion. Further, to demonstrate the use of this assembly process we explored chirality sensing and enantiomeric excess determinations. An induced twist in the ligand by a chiral mono-ol results in large Cotton effects in the circular dichroism spectra indicative of the alcohol’s handedness. The strategy revealed in this study should prove broadly applicable for the incorporation of alcohols into supramolecular architecture construction. PMID:22109274

Flight Measurements of the Effect of a Controllable Thrust Reverser on the Flight Characteristics of a Single-Engine Jet Airplane

NASA Technical Reports Server (NTRS)

Anderson, Seth B.; Cooper, George E.; Faye, Alan E., Jr.

1959-01-01

A flight investigation was undertaken to determine the effect of a fully controllable thrust reverser on the flight characteristics of a single-engine jet airplane. Tests were made using a cylindrical target-type reverser actuated by a hydraulic cylinder through a "beep-type" cockpit control mounted at the base of the throttle. The thrust reverser was evaluated as an in-flight decelerating device, as a flight path control and airspeed control in landing approach, and as a braking device during the ground roll. Full deflection of the reverser for one reverser configuration resulted in a reverse thrust ratio of as much as 85 percent, which at maximum engine power corresponded to a reversed thrust of 5100 pounds. Use of the reverser in landing approach made possible a wide selection of approach angles, a large reduction in approach speed at steep approach angles, improved control of flight path angle, and more accuracy in hitting a given touchdown point. The use of the reverser as a speed brake at lower airspeeds was compromised by a longitudinal trim change. At the lower airspeeds and higher engine powers there was insufficient elevator power to overcome the nose-down trim change at full reverser deflection.

Polyethylene Wear in Retrieved Reverse Total Shoulder Components

PubMed Central

Day, Judd S; MacDonald, Daniel W; Olsen, Madeline; Getz, Charles; Williams, Gerald R; Kurtz, Steven M

2011-01-01

Background Reverse total shoulder arthroplasty has been used to treat rotator cuff tear arthropathy, proximal humeral fractures and for failed conventional total shoulder prostheses. It has been suggested that polyethylene wear is potentially higher in reverse shoulder replacements than in conventional shoulder replacements. The modes and degree of polyethylene wear have not been completely elucidated. The purpose of this study was to evaluate polyethylene wear patterns in seven specimens retrieved at revision arthroplasty and identify factors that may be associated with increased wear. Methods Reverse total shoulder components were retrieved from 7 patients during revision arthroplasty for loosening and/or pain. Pre-operative glenoid tilt and placement, and scapular notching were evaluated using pre-operative radiographs. Polyethylene wear was evaluated using microCT and optical microscopy. Results Wear on the rim of the polyethylene humeral cup, was identified on all retrieved components. The extent of rim wear varied from a penetration depth of 0.1 to 4.7 mm. We could not demonstrate a correlation between scapular notching and rim wear. However, rim wear was more extensive when the inferior screw had made contact with the liner. Metal on metal wear between the humeral component and the inferior screw of one component was also observed. Wear of the intended bearing surface was minimal. Discussion Rim damage was the predominant cause of polyethylene wear in our retrieved specimens. Direct contact between the humeral component and inferior metaglene screws is concerning because this could lead to accelerated UHMWPE wear and also induce mechanical loosening of the glenoid component. PMID:21724419

Acetylcholine-activated ionic currents in parasympathetic neurons of bullfrog heart.

PubMed

Tateishi, N; Kim, D K; Akaike, N

1990-05-01

1. The electrical and pharmacologic properties of acetylcholine (ACh)-induced current (IACh) were studied in the parasympathetic neurons isolated from bullfrog heart with the use of the concentration-clamp technique, which allows intracellular perfusion and rapid change of external solution within 2 ms under the single-electrode voltage-clamp condition. 2. The IACh consisted of an initial transient peak component and a successive steady-state plateau component. Both currents increased in a sigmoidal fashion with increasing ACh concentration. The dissociation constant (Kd value) and the Hill coefficient for each component were 2.2 X 10(-5) M and 1.6, respectively. 3. In the K(+)-free solution, the reversal potential (EACh) of IACh was close to the Na+ equilibrium potential (ENa). The current-voltage (I-V) relation showed inward rectification at positive potentials. 4. Nicotine mimicked only the peak component of IACh. However both peak and steady-state components were blocked nonselectively by the nicotinic blockers d-tubocurarine and hexamethonium. 5. Carbamylcholine (CCh) mimicked the steady-state component of IACh. The steady-state component was selectively inhibited by atropine at concentrations 1,000 times lower than that required for inhibition of the peak component. The steady state was blocked equally by either pirenzepine (M1 blocker) or AF-DX-116 (M2 blocker). 6. It was concluded that the IACh consisted of a peak component having double exponential activation and inactivation, mediated through the nicotinic actions, and a steady-state component having no inactivation, mediated through the muscarinic action.

A novel dynamic mechanical testing technique for reverse shoulder replacements.

PubMed

Dabirrahmani, Danè; Bokor, Desmond; Appleyard, Richard

2014-04-01

In vitro mechanical testing of orthopedic implants provides information regarding their mechanical performance under simulated biomechanical conditions. Current in vitro component stability testing methods for reverse shoulder implants are based on anatomical shoulder designs, which do not capture the dynamic nature of these loads. With glenoid component loosening as one of the most prevalent modes of failure in reverse shoulder replacements, it is important to establish a testing protocol with a more realistic loading regime. This paper introduces a novel method of mechanically testing reverse shoulder implants, using more realistic load magnitudes and vectors, than is currently practiced. Using a custom made jig setup within an Instron mechanical testing system, it is possible to simulate the change in magnitude and direction of the joint load during arm abduction. This method is a step towards a more realistic testing protocol for measuring reverse shoulder implant stability.

Perceptual reversals during binocular rivalry: ERP components and their concomitant source differences.

PubMed

Britz, Juliane; Pitts, Michael A

2011-11-01

We used an intermittent stimulus presentation to investigate event-related potential (ERP) components associated with perceptual reversals during binocular rivalry. The combination of spatiotemporal ERP analysis with source imaging and statistical parametric mapping of the concomitant source differences yielded differences in three time windows: reversals showed increased activity in early visual (∼120 ms) and in inferior frontal and anterior temporal areas (∼400-600 ms) and decreased activity in the ventral stream (∼250-350 ms). The combination of source imaging and statistical parametric mapping suggests that these differences were due to differences in generator strength and not generator configuration, unlike the initiation of reversals in right inferior parietal areas. These results are discussed within the context of the extensive network of brain areas that has been implicated in the initiation, implementation, and appraisal of bistable perceptual reversals. Copyright © 2011 Society for Psychophysiological Research.

Dynamers: Polyacylhydrazone reversible covalent polymers, component exchange, and constitutional diversity

PubMed Central

Skene, Williams G.; Lehn, Jean-Marie P.

2004-01-01

Component exchange in reversible polymers allows the generation of dynamic constitutional diversity. The polycondensation of dihydrazides with dialdehydes generates polyacylhydrazones, to which the acylhydrazone functionality formed confers both hydrogen-bonding and reversibility features through the amide and imine groups, respectively. Polyacylhydrazones are thus dynamic polyamides. They are able to reversibly exchange either one or both of their repeating monomer units in the presence of different monomers, thus presenting constitutional dynamic diversity. The polymers subjected to monomer exchange/interchange may be brought to exhibit physical properties vastly different from those of the original polymer. The principle may be extended to other important classes of polymers, giving access, for instance, to dynamic polyureas or polycarbamates. These reversible polymers are therefore able to incorporate, decorporate, or reshuffle their constituting monomers, namely in response to environmental physical or chemical factors, an adaptability feature central to constitutional dynamic chemistry. PMID:15150411

Evidence for slip partitioning and bimodal slip behavior on a single fault: Surface slip characteristics of the 2013 Mw7.7 Balochistan, Pakistan earthquake

USGS Publications Warehouse

Barnhart, William; Briggs, Richard; Reitman, Nadine G.; Gold, Ryan D.; Hayes, Gavin

2015-01-01

Deformation is commonly accommodated by strain partitioning on multiple, independent strike-slip and dip-slip faults in continental settings of oblique plate convergence. As a corollary, individual faults tend to exhibit one sense of slip – normal, reverse, or strike-slip – until whole-scale changes in boundary conditions reactivate preexisting faults in a new deformation regime. In this study, we show that a single continental fault may instead partition oblique strain by alternatively slipping in a strike-slip or a dip-slip sense during independent fault slip events. We use 0.5 m resolution optical imagery and sub-pixel correlation analysis of the 200+ km 200+km"> 2013 Mw7.7 Balochistan, Pakistan earthquake to document co-seismic surface slip characteristics and Quaternary tectonic geomorphology along the causative Hoshab fault. We find that the 2013 earthquake, which involved a ∼6:1 strike-slip to dip-slip ratio, ruptured a structurally segmented fault. Quaternary geomorphic indicators of gross fault-zone morphology reveal both reverse-slip and strike-slip deformation in the rupture area of the 2013 earthquake that varies systematically along fault strike despite nearly pure strike-slip motion in 2013. Observations of along-strike variations in range front relief and geomorphic offsets suggest that the Hoshab fault accommodates a substantial reverse component of fault slip in the Quaternary, especially along the southern section of the 2013 rupture. We surmise that Quaternary bimodal slip along the Hoshab fault is promoted by a combination of the arcuate geometry of the Hoshab fault, the frictional weakness of the Makran accretionary prism, and time variable loading conditions from adjacent earthquakes and plate interactions.

Evidence for slip partitioning and bimodal slip behavior on a single fault: Surface slip characteristics of the 2013 Mw7.7 Balochistan, Pakistan earthquake

NASA Astrophysics Data System (ADS)

Barnhart, W. D.; Briggs, R. W.; Reitman, N. G.; Gold, R. D.; Hayes, G. P.

2015-06-01

Deformation is commonly accommodated by strain partitioning on multiple, independent strike-slip and dip-slip faults in continental settings of oblique plate convergence. As a corollary, individual faults tend to exhibit one sense of slip - normal, reverse, or strike-slip - until whole-scale changes in boundary conditions reactivate preexisting faults in a new deformation regime. In this study, we show that a single continental fault may instead partition oblique strain by alternatively slipping in a strike-slip or a dip-slip sense during independent fault slip events. We use 0.5 m resolution optical imagery and sub-pixel correlation analysis of the 200 + km 2013 Mw7.7 Balochistan, Pakistan earthquake to document co-seismic surface slip characteristics and Quaternary tectonic geomorphology along the causative Hoshab fault. We find that the 2013 earthquake, which involved a ∼6:1 strike-slip to dip-slip ratio, ruptured a structurally segmented fault. Quaternary geomorphic indicators of gross fault-zone morphology reveal both reverse-slip and strike-slip deformation in the rupture area of the 2013 earthquake that varies systematically along fault strike despite nearly pure strike-slip motion in 2013. Observations of along-strike variations in range front relief and geomorphic offsets suggest that the Hoshab fault accommodates a substantial reverse component of fault slip in the Quaternary, especially along the southern section of the 2013 rupture. We surmise that Quaternary bimodal slip along the Hoshab fault is promoted by a combination of the arcuate geometry of the Hoshab fault, the frictional weakness of the Makran accretionary prism, and time variable loading conditions from adjacent earthquakes and plate interactions.

Rapid and specific detection of Yam mosaic virus by reverse-transcription recombinase polymerase amplification.

PubMed

Silva, Gonçalo; Bömer, Moritz; Nkere, Chukwuemeka; Kumar, P Lava; Seal, Susan E

2015-09-15

Yam mosaic virus (YMV; genus Potyvirus) is considered to cause the most economically important viral disease of yams (Dioscorea spp.) in West Africa which is the dominant region for yam production globally. Yams are a vegetatively propagated crop and the use of virus-free planting material forms an essential component of disease control. Current serological and PCR-based diagnostic methods for YMV are time consuming involving a succession of target detection steps. In this study, a novel assay for specific YMV detection is described that is based on isothermal reverse transcription-recombinase polymerase amplification (RT-exoRPA). This test has been shown to be reproducible and able to detect as little as 14 pg/μl of purified RNA obtained from an YMV-infected plant, a sensitivity equivalent to that obtained with the reverse transcription-polymerase chain reaction (RT-PCR) in current general use. The RT-exoRPA assay has, however, several advantages over the RT-PCR; positive samples can be detected in less than 30 min, and amplification only requires a single incubation temperature (optimum 37°C). These features make the RT-exoRPA assay a promising candidate for adapting into a field test format to be used by yam breeding programmes or certification laboratories. Copyright © 2015 Elsevier B.V. All rights reserved.

Time-Reversal Location of the 2004 M6.0 Parkfield Earthquake Using the Vertical Component of Seismic Data.

NASA Astrophysics Data System (ADS)

Larmat, C. S.; Johnson, P.; Huang, L.; Randall, G.; Patton, H.; Montagner, J.

2007-12-01

In this work we describe Time Reversal experiments applying seismic waves recorded from the 2004 M6.0 Parkfield Earthquake. The reverse seismic wavefield is created by time-reversing recorded seismograms and then injecting them from the seismograph locations into a whole entire Earth velocity model. The concept is identical to acoustic Time-Reversal Mirror laboratory experiments except the seismic data are numerically backpropagated through a velocity model (Fink, 1996; Ulrich et al, 2007). Data are backpropagated using the finite element code SPECFEM3D (Komatitsch et al, 2002), employing the velocity model s20rts (Ritsema et al, 2000). In this paper, we backpropagate only the vertical component of seismic data from about 100 broadband surface stations located worldwide (FDSN), using the period band of 23-120s. We use those only waveforms that are highly correlated with forward-propagated synthetics. The focusing quality depends upon the type of waves back- propagated; for the vertical displacement component the possible types include body waves, Rayleigh waves, or their combination. We show that Rayleigh waves, both real and artifact, dominate the reverse movie in all cases. They are created during rebroadcast of the time reverse signals, including body wave phases, because we use point-like-force sources for injection. The artifact waves, termed "ghosts" manifest as surface waves, do not correspond to real wave phases during the forward propagation. The surface ghost waves can significantly blur the focusing at the source. We find that the ghosts cannot be easily eliminated in the manner described by Tsogka&Papanicolaou (2002). It is necessary to understand how they are created in order to remove them during TRM studies, particularly when using only the body waves. For this moderate magnitude of earthquake we demonstrate the robustness of the TRM as an alternative location method despite the restriction to vertical component phases. One advantage of TRM location is that it does not rely on a prior picking of specific phases (Larmat et al, 2006). In future work will be conducted TRM backpropagation using the horizontal displacement components of seismic data as well as study the source complexity (double couples). Our ultimate goal is to determine whether or not Time Reversal offers information about the source that cannot be obtained from other methods, or that complements other methods.

Magnetization Reversal Process of Single Crystal α-Fe Containing a Nonmagnetic Particle

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

Li, Yi; Xu, Ben; Hu, Shenyang Y.

2015-09-25

The magnetization reversal process and hysteresis loops in a single crystal α-iron with nonmagnetic particles are simulated in this work based on the Landau-Lifshitz–Gilbert equation. The evolutions of the magnetic domain morphology are studied, and our analyses show that the magnetization reversal process is affected by the interaction between the moving domain wall and the existing nonmagnetic particles. This interaction strongly depends on the size of the particles, and it is found that particles with a particular size contribute the most to magnetic hardening.

To Design or Not to Design: In Conclusion

DTIC Science & Technology

2011-05-09

planning performing bricolage and assembling components of Design into detailed planning logic, the military might consider reversing this process and...while incorporated into Design‟s holistic worldview. The process of bricolage would subsequently reverse, and those relevant components of detailed...production, defined as “ bricolage ” in organizational theory circles, turns one into „a handyperson who, rather than inventing a new theory or a new

Thermosensitive multilayer hydrogels of poly(N-vinylcaprolactam) as nanothin films and shaped capsules.

PubMed

Liang, Xing; Kozlovskaya, Veronika; Chen, Yi; Zavgorodnya, Oleksandra; Kharlampieva, Eugenia

2012-08-09

We report on nanothin multilayer hydrogels of cross-linked poly(N-vinylcaprolactam) (PVCL) that exhibit distinctive and reversible thermoresponsive behavior. The single-component PVCL hydrogels were produced by selective cross-linking of PVCL in layer-by-layer films of PVCL-NH(2) copolymers assembled with poly(methacrylic acid) (PMAA) via hydrogen bonding. The degree of the PVCL hydrogel film shrinkage, defined as the ratio of wet thicknesses at 25°C to 50°C, was demonstrated to be 1.9±0.1 and 1.3±0.1 for the films made from PVCL-NH(2)-7 and PVCL-NH(2)-14 copolymers, respectively. No temperature-responsive behavior was observed for non-cross-linked two-component films due to the presence of PMAA. We also demonstrated that temperature-sensitive PVCL capsules of cubical and spherical shapes could be fabricated as hollow hydrogel replicas of inorganic templates. The cubical (PVCL)(7) capsules retained their cubical shape when temperature was elevated from 25°C to 50°C exhibiting 21±1% decrease in the capsule size. Spherical hydrogel capsules demonstrated similar shrinkage of 23±1%. The temperature-triggered capsule size changes were completely reversible. Our work opens new prospects for developing biocompatible and nanothin hydrogel-based coatings and containers for temperate-regulating drug delivery, cellular uptake, sensing, and transport behavior in microfluidic devices.

A nanometre-scale electronic switch consisting of a metal cluster and redox-addressable groups.

PubMed

Gittins, D I; Bethell, D; Schiffrin, D J; Nichols, R J

2000-11-02

So-called bottom-up fabrication methods aim to assemble and integrate molecular components exhibiting specific functions into electronic devices that are orders of magnitude smaller than can be fabricated by lithographic techniques. Fundamental to the success of the bottom-up approach is the ability to control electron transport across molecular components. Organic molecules containing redox centres-chemical species whose oxidation number, and hence electronic structure, can be changed reversibly-support resonant tunnelling and display promising functional behaviour when sandwiched as molecular layers between electrical contacts, but their integration into more complex assemblies remains challenging. For this reason, functionalized metal nanoparticles have attracted much interest: they exhibit single-electron characteristics (such as quantized capacitance charging) and can be organized through simple self-assembly methods into well ordered structures, with the nanoparticles at controlled locations. Here we report scanning tunnelling microscopy measurements showing that organic molecules containing redox centres can be used to attach metal nanoparticles to electrode surfaces and so control the electron transport between them. Our system consists of gold nanoclusters a few nanometres across and functionalized with polymethylene chains that carry a central, reversibly reducible bipyridinium moiety. We expect that the ability to electronically contact metal nanoparticles via redox-active molecules, and to alter profoundly their tunnelling properties by charge injection into these molecules, can form the basis for a range of nanoscale electronic switches.

Reversible pyroelectric and photogalvanic current in epitaxial Pb(Zr0.52Ti0.48)O3 thin films

NASA Astrophysics Data System (ADS)

Lee, J.; Esayan, S.; Prohaska, J.; Safari, A.

1994-01-01

The pyroelectric and photogalvanic effects have been studied in epitaxial Pb(Zr0.52Ti0.48)O3 (PZT) thin films. Photoinduced currents, which were completely reversible by electrical voltage, were observed. The photoinduced currents exhibited transient and steady state components. The transient component, in turn, consisted of two components with fast (<1 s) and slow (˜hours) relaxation times. The mechanisms of the photoinduced currents in PZT films and their possible applications in nondestructive readout ferroelectric memory are discussed.

Durations of Recognition for Single Letters, with and without Visual Masking, by Dyslexics and Normal Readers.

ERIC Educational Resources Information Center

Grosser, George S.; Trzeciak, Gerda M.

1981-01-01

Two sets of letters, those subject to reversal/rotation and others, were tachistoscopically presented singly to normal readers and dyslexic children. The data support the hypothesis that letters subject to reversal have no special relation to dyslexia. The view that dyslexia is a developmental anomaly was supported. (Author/AL)

Final-state effect on x-ray photoelectron spectrum of nominally d1 and n -doped d0 transition-metal oxides

NASA Astrophysics Data System (ADS)

Lin, Chungwei; Posadas, Agham; Hadamek, Tobias; Demkov, Alexander A.

2015-07-01

We investigate the x-ray photoelectron spectroscopy (XPS) of nominally d1 and n -doped d0 transition-metal oxides including NbO2,SrVO3, and LaTiO3 (nominally d1), as well as n -doped SrTiO3 (nominally d0). In the case of single phase d1 oxides, we find that the XPS spectra (specifically photoelectrons from Nb 3 d , V 2 p , Ti 2 p core levels) all display at least two, and sometimes three distinct components, which can be consistently identified as d0,d1, and d2 oxidation states (with decreasing order in binding energy). Electron doping increases the d2 component but decreases the d0 component, whereas hole doping reverses this trend; a single d1 peak is never observed, and the d0 peak is always present even in phase-pure samples. In the case of n -doped SrTiO3, the d1 component appears as a weak shoulder with respect to the main d0 peak. We argue that these multiple peaks should be understood as being due to the final-state effect and are intrinsic to the materials. Their presence does not necessarily imply the existence of spatially localized ions of different oxidation states nor of separate phases. A simple model is provided to illustrate this interpretation, and several experiments are discussed accordingly. The key parameter to determine the relative importance between the initial-state and final-state effects is also pointed out.

Development of reversible jump Markov Chain Monte Carlo algorithm in the Bayesian mixture modeling for microarray data in Indonesia

NASA Astrophysics Data System (ADS)

Astuti, Ani Budi; Iriawan, Nur; Irhamah, Kuswanto, Heri

2017-12-01

In the Bayesian mixture modeling requires stages the identification number of the most appropriate mixture components thus obtained mixture models fit the data through data driven concept. Reversible Jump Markov Chain Monte Carlo (RJMCMC) is a combination of the reversible jump (RJ) concept and the Markov Chain Monte Carlo (MCMC) concept used by some researchers to solve the problem of identifying the number of mixture components which are not known with certainty number. In its application, RJMCMC using the concept of the birth/death and the split-merge with six types of movement, that are w updating, θ updating, z updating, hyperparameter β updating, split-merge for components and birth/death from blank components. The development of the RJMCMC algorithm needs to be done according to the observed case. The purpose of this study is to know the performance of RJMCMC algorithm development in identifying the number of mixture components which are not known with certainty number in the Bayesian mixture modeling for microarray data in Indonesia. The results of this study represent that the concept RJMCMC algorithm development able to properly identify the number of mixture components in the Bayesian normal mixture model wherein the component mixture in the case of microarray data in Indonesia is not known for certain number.

A re-appraisal of the proposed rapid Matuyama-Brunhes geomagnetic reversal in the Sulmona Basin, Italy

NASA Astrophysics Data System (ADS)

Evans, M. E.; Muxworthy, A. R.

2018-06-01

An extremely sharp magnetic reversal observed in lacustrine sediments in central Italy has been interpreted as a record of the Matuyama-Brunhes geomagnetic polarity reversal that may represent less than a decade. Here, we report new results from the same Sulmona Basin outcrops that question this interpretation. In particular, we find evidence of reversed (Matuyama) directions well above the proposed Matuyama-Brunhes Boundary (MBB). Coercivity spectra of anhysteretic remanent magnetization imply a three-component magnetic mineralogy: low-, intermediate- and high-coercivity. The low-coercivity component is found in all but one of the samples and carries a strong modern overprint seen throughout the section. The high-coercivity component is dominated by volcanic material which is prone to remagnetization. Since it is much more magnetic than the surrounding lacustrine sediments, it may influence the remanence signal even when present at very low concentrations. The intermediate-coercivity component is the main carrier of any true primary remanence, but whether or not this can be isolated depends on the blocking temperature and coercivity spectra of individual samples and on the demagnetization method used. The complexity of the magnetization, the reversed zones above the proposed MBB and the normal zones that Sagnotti and colleagues found below it lead to the conclusion that this section does not carry a reliable high-resolution record of the geomagnetic field. Thus, we feel that inferences about the stratigraphic position and duration of the MBB are premature.

Rapid amino acid quantitation with pre-column derivatization; ultra-performance reverse phase liquid chromatography and single quadrupole mass spectrometry.

PubMed

Pretorius, Carel J; McWhinney, Brett C; Sipinkoski, Bilyana; Wilce, Alice; Cox, David; McWhinney, Avis; Ungerer, Jacobus P J

2018-03-01

We optimized a quantitative amino acid method with pre-column derivatization, norvaline (nva) internal standard and reverse phase ultra-performance liquid chromatography by replacing the ultraviolet detector with a single quadrupole mass spectrometer (MS nva ). We used 13 C 15 N isotopically labeled amino acid internal standards and a C18 column with 1.6μm particles to optimize the chromatography and to confirm separation of isobaric compounds (MS lis ). We compared the analytical performance of MS nva with MS lis and the original method (UV nva ) with clinical samples. The chromatography time per sample of MS nva was 8min, detection capabilities were <1μmol/L for most components, intermediate imprecisions at low concentrations were <10% and there was negligible carryover. MS nva was linear up to a total amino acid concentration in a sample of approximately 9500μmol/L. The agreements between most individual amino acids were satisfactory compared to UV nva with the latter prone to outliers and suboptimal quantitation of urinary arginine, aspartate, glutamate and methionine. MS nva reliably detected argnininosuccinate, β-alanine, citrulline and cysteine-s-sulfate. MS nva resulted in a more than fivefold increase in operational efficiency with accurate detection of amino acids and metabolic intermediates in clinical samples. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Quantitative determination of major active components in Ginkgo biloba dietary supplements by liquid chromatography/mass spectrometry.

PubMed

Ding, Shujing; Dudley, Ed; Plummer, Sue; Tang, Jiandong; Newton, Russell P; Brenton, A Gareth

2006-01-01

A reversed-phase high-performance liquid chromatography/electrospray ionisation mass spectrometry (RP-HPLC/ESI-MS) method was developed and validated for the simultaneous determination of ten major active components in Ginkgo biloba extract (bilobalide, ginkgolides A, B, C, quercetin, kaempferol, isorhamnetin, rutin hydrate, quercetin-3-beta-D-glucoside and quercitrin hydrate) which have not been previously reported to be quantified in a single analysis. The ten components exhibit baseline separation in 50 min by C18 chromatography using a water/1:1 (v/v) methanol/acetonitrile gradient. Quantitation was performed using negative ESI-MS in selected ion monitoring (SIM) mode. Good reproducibility and recovery were obtained by this method. The sensitivity of both UV and different mass spectrometry modes (full scan, selected ion monitoring (SIM), and selected reaction monitoring (SRM)) were compared and both quantitation with and without internal standard were evaluated. The analysis of Ginkgo biloba commercial products showed remarkable variations in the rutin and quercetin content as well as the terpene lactone contents although all the products satisfy the conventional quality control method. Copyright 2006 John Wiley & Sons, Ltd.

Robot-assisted vasovasostomy using a single layer anastomosis.

PubMed

Marshall, Michael T; Doudt, Alexander D; Berger, Jonathan H; Auge, Brian K; Christman, Matthew S; Choe, Chong H

2017-09-01

Of all patients who have vasectomies performed in the United States, upwards of 6% will pursue a vasectomy reversal. Currently, the gold-standard reversal procedure is a microscopic vasovasostomy utilizing either a one or two-layer vasal anastomosis. Unfortunately, most urologists do not perform these procedures as they require extensive training and experience in microsurgery. The objective of our study was to evaluate the feasibility and success rate of robot-assisted vasovasostomy performed at our institution. We completed a retrospective review of our experience with vasectomy reversal utilizing the da Vinci ® Surgical System and a single layer vasal anastomosis. A successful reversal was defined as a return of sperm on semen analysis or light microscopy. Since 2009 we have completed 79 robotic vasectomy reversals, 60 of which utilized a single-layer vasal anastomosis. The average obstructive interval was 5.7 ± 2.2 years. Average operative time was 192 min. 42 patients returned for a post-operative semen evaluation at an average time of 4.3 months post-procedure revealing a success rate of 88% (37 out of 42). Post-operative semen parameters were significant for an average sperm density of 31.0 million/mL with an average motility of 29.1%. Robot-assisted vasovasostomy with a single layer anastomosis has overall success rates that are similar to that of reported microscopic vasovasostomy rates. Although more study is warranted with regard to cost, we feel as though our study demonstrates an alternative approach to vasectomy reversal that can be performed successfully by urologists trained in robotic surgery.

Direct observation of dynamical magnetization reversal process governed by shape anisotropy in single NiFe2O4 nanowire.

PubMed

Zhang, Junli; Zhu, Shimeng; Li, Hongli; Zhu, Liu; Hu, Yang; Xia, Weixing; Zhang, Xixiang; Peng, Yong; Fu, Jiecai

2018-05-31

Discovering how the magnetization reversal process is governed by the magnetic anisotropy in magnetic nanomaterials is essential and significant to understand the magnetic behaviour of micro-magnetics and to facilitate the design of magnetic nanostructures for diverse technological applications. In this study, we present a direct observation of a dynamical magnetization reversal process in single NiFe2O4 nanowire, thus clearly revealing the domination of shape anisotropy on its magnetic behaviour. Individual nanoparticles on the NiFe2O4 nanowire appear as single domain states in the remanence state, which is maintained until the magnetic field reaches 200 Oe. The magnetization reversal mechanism of the nanowire is observed to be a curling rotation mode. These observations are further verified by micromagnetic computational simulations. Our findings show that the modulation of shape anisotropy is an efficient way to tune the magnetic behaviours of cubic spinel nano-ferrites.

Efficient Nitrogen Fixation via a Redox-Flexible Single-Iron Site with Reverse-Dative Iron → Boron σ Bonding.

PubMed

Lu, Jun-Bo; Ma, Xue-Lu; Wang, Jia-Qi; Liu, Jin-Cheng; Xiao, Hai; Li, Jun

2018-05-10

Model systems of the FeMo cofactor of nitrogenase have been explored extensively in catalysis to gain insights into their ability for nitrogen fixation that is of vital importance to the human society. Here we investigate the trigonal pyramidal borane-ligand Fe complex by first-principles calculations, and find that the variation of oxidation state of Fe along the reaction path correlates with that of the reverse-dative Fe → B bonding. The redox-flexibility of the reverse-dative Fe → B bonding helps to provide an electron reservoir that buffers and stabilizes the evolution of Fe oxidation state, which is essential for forming the key intermediates of N 2 activation. Our work provides insights for understanding and optimizing homogeneous and surface single-atom catalysts with reverse-dative donating ligands for efficient dinitrogen fixation. The extension of this kind of molecular catalytic active center to heterogeneous catalysts with surface single-clusters is also discussed.

Process of forming compounds using reverse micelle or reverse microemulsion systems

DOEpatents

Linehan, John C.; Fulton, John L.; Bean, Roger M.

1998-01-01

The present invention is directed to a process for producing a nanometer-sized metal compound. The process comprises forming a reverse micelle or reverse microemulsion system comprising a polar fluid in a non-polar or low-polarity fluid. A first reactant comprising a multi-component, water-soluble metal compound is introduced into the polar fluid in a non-polar or low-polarity fluid. This first reactant can be introduced into the reverse micelle or reverse microemulsion system during formation thereof or subsequent to the formation of the reverse micelle or microemulsion system. The water-soluble metal compound is then reacted in the reverse micelle or reverse microemulsion system to form the nanometer-sized metal compound. The nanometer-sized metal compound is then precipitated from the reverse micelle or reverse microemulsion system.

Improved RF Isolation Amplifier

NASA Technical Reports Server (NTRS)

Stevens, G. L.; Macconnell, J.

1985-01-01

Circuit has high reverse isolation and wide bandwidth. Wideband isolation amplifier has low intermodulation distortion and high reverse isolation. Circuit does not require selected or matched components or directional coupling device. Circuit used in applications requiring high reverse isolation such as receiver intermediate-frequency (IF) strips and frequency distribution systems. Also applicable in RF and video signaling.

Teaching Foundational Perspective-taking Skills to Children with Autism Using the PEAK-T Curriculum: Single-Reversal "I-You" Deictic Frames

ERIC Educational Resources Information Center

Belisle, Jordan; Dixon, Mark R.; Stanley, Caleb R.; Munoz, Bridget; Daar, Jacob H.

2016-01-01

We taught basic perspective-taking tasks to 3 children with autism and evaluated their ability to derive mutually entailed single-reversal deictic relations of those newly established perspective-taking skills. Furthermore, we examined the possibility of transfers of perspective-taking function to novel untrained stimuli. The methods were taken…

Reverse-Tangent Injection in a Centrifugal Compressor

NASA Technical Reports Server (NTRS)

Skoch, Gary J.

2007-01-01

Injection of working fluid into a centrifugal compressor in the reverse tangent direction has been invented as a way of preventing flow instabilities (stall and surge) or restoring stability when stall or surge has already commenced. The invention applies, in particular, to a centrifugal compressor, the diffuser of which contains vanes that divide the flow into channels oriented partly radially and partly tangentially. In reverse-tangent injection, a stream or jet of the working fluid (the fluid that is compressed) is injected into the vaneless annular region between the blades of the impeller and the vanes of the diffuser. As used here, "reverse" signifies that the injected flow opposes (and thereby reduces) the tangential component of the velocity of the impeller discharge. At the same time, the injected jet acts to increase the radial component of the velocity of the impeller discharge.

Influence of magnetic field on zebrafish activity and orientation in a plus maze.

PubMed

Osipova, Elena A; Pavlova, Vera V; Nepomnyashchikh, Valentin A; Krylov, Viacheslav V

2016-01-01

We describe an impact of the geomagnetic field (GMF) and its modification on zebrafish's orientation and locomotor activity in a plus maze with four arms oriented to the north, east, south and west. Zebrafish's directional preferences were bimodal in GMF: they visited two arms oriented in opposed directions (east-west) most frequently. This bimodal preference remained stable for same individuals across experiments divided by several days. When the horizontal GMF component was turned 90° clockwise, the preference accordingly shifted by 90° to arms oriented to the north and south. Other modifications of GMF (reversal of both vertical and horizontal GMF components; reversal of vertical component only; and reversal of horizontal component only) did not exert any discernible effect on the orientation of zebrafish. The 90° turn of horizontal component also resulted in a significant increase of fish's locomotor activity in comparison with the natural GMF. This increase became even more pronounced when the horizontal component was repeatedly turned by 90° and back with 1min interval between turns. Our results show that GMF and its variations should be taken into account when interpreting zebrafish's directional preferences and locomotor activity in mazes and other experimental devices. Copyright © 2015. Published by Elsevier B.V.

Untethered Recyclable Tubular Actuators with Versatile Locomotion for Soft Continuum Robots.

PubMed

Qian, Xiaojie; Chen, Qiaomei; Yang, Yang; Xu, Yanshuang; Li, Zhen; Wang, Zhenhua; Wu, Yahe; Wei, Yen; Ji, Yan

2018-05-27

Stimuli-responsive materials offer a distinguished platform to build tether-free compact soft robots, which can combine sensing and actuation without a linked power supply. In the past, tubular soft robots have to be made by multiple components with various internal channels or complex cavities assembled together. Moreover, robust processing, complex locomotion, simple structure, and easy recyclability represent major challenges in this area. Here, it is shown that those challenges can be tackled by liquid crystalline elastomers with allyl sulfide functional groups. The light-controlled exchange reaction between allyl sulfide groups allows flexible processing of tubular soft robots/actuators, which does not need any assisting materials. Complex locomotion demonstrated here includes reversible simultaneous bending and elongation; reversible diameter expansion; and omnidirectional bending via remote infrared light control. Different modes of actuation can be programmed into the same tube without the routine assembly of multiple tubes as used in the past. In addition, the exchange reaction also makes it possible to use the same single tube repeatedly to perform different functions by erasing and reprogramming. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous concentration and purification through gradient deformation chromatography

NASA Technical Reports Server (NTRS)

Velayudhan, A.; Hendrickson, R. L.; Ladisch, M. R.; Mitchell, C. A. (Principal Investigator)

1995-01-01

Mobile-phase additives, commonly used to modulate absorbate retention in gradient elution chromatography, are usually assumed to be either linearly retained or unretained. Previous theoretical work from our laboratory has shown that these modulators, such as salts in ion-exchange and hydrophobic interaction chromatography and organic modifiers in reversed-phase chromatography, can absorb nonlinearly, giving rise to gradient deformation. Consequently, adsorbate peaks that elute in the vicinity of the head of the deformed gradient may exhibit unusual shapes, form shoulders, and/or be concentrated. These effects for a reversed-phase sorbent with aqueous acetonitrile (ACN) as the modulator are verified experimentally. Gradient deformation is demonstrated experimentally and agrees with simulations based on ACN isotherm parameters that are independently determined from batch equilibrium studies using the layer model. Unusual absorbate peak shapes were found experimentally for single-component injections of phenylalanine, similar to those calculated by the simulations. A binary mixture of tryptophan and phenylalanine is used to demonstrate simultaneous concentration and separation, again in agreement with simulations. The possibility of gradient deformation in ion-exchange and hydrophobic interaction chromatography is discussed.

Printing 2-dimentional droplet array for single-cell reverse transcription quantitative PCR assay with a microfluidic robot.

PubMed

Zhu, Ying; Zhang, Yun-Xia; Liu, Wen-Wen; Ma, Yan; Fang, Qun; Yao, Bo

2015-04-01

This paper describes a nanoliter droplet array-based single-cell reverse transcription quantitative PCR (RT-qPCR) assay method for quantifying gene expression in individual cells. By sequentially printing nanoliter-scale droplets on microchip using a microfluidic robot, all liquid-handling operations including cell encapsulation, lysis, reverse transcription, and quantitative PCR with real-time fluorescence detection, can be automatically achieved. The inhibition effect of cell suspension buffer on RT-PCR assay was comprehensively studied to achieve high-sensitivity gene quantification. The present system was applied in the quantitative measurement of expression level of mir-122 in single Huh-7 cells. A wide distribution of mir-122 expression in single cells from 3061 copies/cell to 79998 copies/cell was observed, showing a high level of cell heterogeneity. With the advantages of full-automation in liquid-handling, simple system structure, and flexibility in achieving multi-step operations, the present method provides a novel liquid-handling mode for single cell gene expression analysis, and has significant potentials in transcriptional identification and rare cell analysis.

Printing 2-Dimentional Droplet Array for Single-Cell Reverse Transcription Quantitative PCR Assay with a Microfluidic Robot

PubMed Central

Zhu, Ying; Zhang, Yun-Xia; Liu, Wen-Wen; Ma, Yan; Fang, Qun; Yao, Bo

2015-01-01

This paper describes a nanoliter droplet array-based single-cell reverse transcription quantitative PCR (RT-qPCR) assay method for quantifying gene expression in individual cells. By sequentially printing nanoliter-scale droplets on microchip using a microfluidic robot, all liquid-handling operations including cell encapsulation, lysis, reverse transcription, and quantitative PCR with real-time fluorescence detection, can be automatically achieved. The inhibition effect of cell suspension buffer on RT-PCR assay was comprehensively studied to achieve high-sensitivity gene quantification. The present system was applied in the quantitative measurement of expression level of mir-122 in single Huh-7 cells. A wide distribution of mir-122 expression in single cells from 3061 copies/cell to 79998 copies/cell was observed, showing a high level of cell heterogeneity. With the advantages of full-automation in liquid-handling, simple system structure, and flexibility in achieving multi-step operations, the present method provides a novel liquid-handling mode for single cell gene expression analysis, and has significant potentials in transcriptional identification and rare cell analysis. PMID:25828383

A novel method to study single-particle dynamics by the resistive pulse technique

NASA Astrophysics Data System (ADS)

Berge, L. I.; Feder, J.; Jøssang, T.

1989-08-01

We have developed a new method, a pressure-reversal technique, which extends the uses of the resistive pulse (Coulter counter) technique to single-particle dynamics. The resistive pulse technique measures the increase in resistance when particles suspended in an electrolyte are transported through a current-carrying aperture. By the new method, the pressure is reversed when a particle exits the pore. A trigger signal, derived from the particle pulses, is used to activate two miniature solenoid valves which serve as pressure switches. In this way, the particle reenters the pore. A single particle flowing back and forth may be studied over a long period of time. The time the particle spends outside the pore between reversals is variable from a few milliseconds to several seconds. We have so far used pore diameters in the range of 3-30 μm. The new technique enables us to study single-particle dissolution and single-particle flow dynamics. The experimental arrangement and the details of the new method are described together with some illustrative measurements.

Fast separation of triterpenoid saponins using supercritical fluid chromatography coupled with single quadrupole mass spectrometry.

PubMed

Huang, Yang; Zhang, Tingting; Zhou, Haibo; Feng, Ying; Fan, Chunlin; Chen, Weijia; Crommen, Jacques; Jiang, Zhengjin

2016-03-20

Triterpenoid saponins (TSs) are the most important components of some traditional Chinese medicines (TCMs) and have exhibited valuable pharmacological properties. In this study, a rapid and efficient method was developed for the separation of kudinosides, stauntosides and ginsenosides using supercritical fluid chromatography coupled with single quadrupole mass spectrometry (SFC-MS). The separation conditions for the selected TSs were carefully optimized after the initial screening of eight stationary phases. The best compromise for all compounds in terms of chromatographic performance and MS sensitivity was obtained when water (5-10%) and formic acid (0.05%) were added to the supercritical carbon dioxide/MeOH mobile phase. Beside the composition of the mobile phase, the nature of the make-up solvent for interfacing SFC with MS was also evaluated. Compared to reversed phase liquid chromatography, the SFC approach showed higher resolution and shorter running time. The developed SFC-MS methods were successfully applied to the separation and identification of TSs present in Ilex latifolia Thunb., Panax quinquefolius L. and Panax ginseng C.A. Meyer. These results suggest that this SFC-MS approach could be employed as a useful tool for the quality assessment of natural products containing TSs as active components. Copyright © 2015 Elsevier B.V. All rights reserved.

Combined in vitro transcription and reverse transcription to amplify and label complex synthetic oligonucleotide probe libraries.

PubMed

Murgha, Yusuf; Beliveau, Brian; Semrau, Kassandra; Schwartz, Donald; Wu, Chao-Ting; Gulari, Erdogan; Rouillard, Jean-Marie

2015-06-01

Oligonucleotide microarrays allow the production of complex custom oligonucleotide libraries for nucleic acid detection-based applications such as fluorescence in situ hybridization (FISH). We have developed a PCR-free method to make single-stranded DNA (ssDNA) fluorescent probes through an intermediate RNA library. A double-stranded oligonucleotide library is amplified by transcription to create an RNA library. Next, dye- or hapten-conjugate primers are used to reverse transcribe the RNA to produce a dye-labeled cDNA library. Finally the RNA is hydrolyzed under alkaline conditions to obtain the single-stranded fluorescent probes library. Starting from unique oligonucleotide library constructs, we present two methods to produce single-stranded probe libraries. The two methods differ in the type of reverse transcription (RT) primer, the incorporation of fluorescent dye, and the purification of fluorescent probes. The first method employs dye-labeled reverse transcription primers to produce multiple differentially single-labeled probe subsets from one microarray library. The fluorescent probes are purified from excess primers by oligonucleotide-bead capture. The second method uses an RNA:DNA chimeric primer and amino-modified nucleotides to produce amino-allyl probes. The excess primers and RNA are hydrolyzed under alkaline conditions, followed by probe purification and labeling with amino-reactive dyes. The fluorescent probes created by the combination of transcription and reverse transcription can be used for FISH and to detect any RNA and DNA targets via hybridization.

FORCinel Version 3.0: An Integrated Environment for Processing, Analysis and Simulation of First-Order Reversal Curve Diagrams

NASA Astrophysics Data System (ADS)

Lascu, I.; Harrison, R. J.

2016-12-01

First-order reversal curve (FORC) diagrams are a powerful method to characterise the hysteresis properties of magnetic grain ensembles. Methods of processing, analysis and simulation of FORC diagrams have developed rapidly over the past few years, dramatically expanding their utility within rock magnetic research. Here we announce the latest release of FORCinel (Version 3.0), which integrates many of these developments into a unified, user-friendly package running within Igor Pro (www.wavemetrics.com). FORCinel v. 3.0 can be downloaded from https://wserv4.esc.cam.ac.uk/nanopaleomag/. The release will be accompanied by a series of video tutorials outlining each of the new features, including: i) improved work flow, with unified smoothing approach; ii) increased processing speed using multiple processors; iii) control of output resolution, enabling large datasets (> 500 FORCs) to be smoothed in a matter of seconds; iv) load, process, analyse and average multiple FORC diagrams; v) load and process non-gridded data and data acquired on non-PMC systems; vi) improved method for exploring optimal smoothing parameters; vii) interactive and un-doable data-pretreatments; viii) automated detection and removal of measurement outliers; ix) improved interactive method for the generation and optimisation of colour scales; x) full integration with FORCem1 - supervised quantitative unmixing of FORC diagrams using principle component analysis (PCA); xi) full integration with FORCulator2 - micromagnetic simulation of FORC diagrams; xiii) simulate TRM acquisition using the kinetic Monte Carlo simulation algorithm of Shcherbakov3. 1. Lascu, I., Harrison, R.J., Li, Y., Muraszko, J.R., Channell, J.E.T., Piotrowski, A.M., Hodell, D.A., 2015. Magnetic unmixing of first-order reversal curve diagrams using principal component analysis. Geochemistry, Geophys. Geosystems 16, 2900-2915. 2. Harrison, R.J., Lascu, I., 2014. FORCulator: A micromagnetic tool for simulating first-order reversal curve diagrams. Geochemistry Geophys. Geosystems 15, 4671-4691. 3. Shcherbakov, V.P., Lamash, B.E., Sycheva, N.K., 1995. Monte-Carlo modelling of thermoremanence acquisition in interacting single-domain grains. Phys. Earth Planet. Inter. 87, 197-211.

Substructure based modeling of nickel single crystals cycled at low plastic strain amplitudes

NASA Astrophysics Data System (ADS)

Zhou, Dong

In this dissertation a meso-scale, substructure-based, composite single crystal model is fully developed from the simple uniaxial model to the 3-D finite element method (FEM) model with explicit substructures and further with substructure evolution parameters, to simulate the completely reversed, strain controlled, low plastic strain amplitude cyclic deformation of nickel single crystals. Rate-dependent viscoplasticity and Armstrong-Frederick type kinematic hardening rules are applied to substructures on slip systems in the model to describe the kinematic hardening behavior of crystals. Three explicit substructure components are assumed in the composite single crystal model, namely "loop patches" and "channels" which are aligned in parallel in a "vein matrix," and persistent slip bands (PSBs) connected in series with the vein matrix. A magnetic domain rotation model is presented to describe the reverse magnetostriction of single crystal nickel. Kinematic hardening parameters are obtained by fitting responses to experimental data in the uniaxial model, and the validity of uniaxial assumption is verified in the 3-D FEM model with explicit substructures. With information gathered from experiments, all control parameters in the model including hardening parameters, volume fraction of loop patches and PSBs, and variation of Young's modulus etc. are correlated to cumulative plastic strain and/or plastic strain amplitude; and the whole cyclic deformation history of single crystal nickel at low plastic strain amplitudes is simulated in the uniaxial model. Then these parameters are implanted in the 3-D FEM model to simulate the formation of PSB bands. A resolved shear stress criterion is set to trigger the formation of PSBs, and stress perturbation in the specimen is obtained by several elements assigned with PSB material properties a priori. Displacement increment, plastic strain amplitude control and overall stress-strain monitor and output are carried out in the user subroutine DISP and URDFIL of ABAQUS, respectively, while constitutive formulations of the FEM model are coded and implemented in UMAT. The results of the simulations are compared to experiments. This model verified the validity of Winter's two-phase model and Taylor's uniform stress assumption, explored substructure evolution and "intrinsic" behavior in substructures and successfully simulated the process of PSB band formation and propagation.

Reversible adapting layer produces robust single-crystal electrocatalyst for oxygen evolution.

PubMed

Tung, Ching-Wei; Hsu, Ying-Ya; Shen, Yen-Ping; Zheng, Yixin; Chan, Ting-Shan; Sheu, Hwo-Shuenn; Cheng, Yuan-Chung; Chen, Hao Ming

2015-08-28

Electrochemically converting water into oxygen/hydrogen gas is ideal for high-density renewable energy storage in which robust electrocatalysts for efficient oxygen evolution play crucial roles. To date, however, electrocatalysts with long-term stability have remained elusive. Here we report that single-crystal Co3O4 nanocube underlay with a thin CoO layer results in a high-performance and high-stability electrocatalyst in oxygen evolution reaction. An in situ X-ray diffraction method is developed to observe a strong correlation between the initialization of the oxygen evolution and the formation of active metal oxyhydroxide phase. The lattice of skin layer adapts to the structure of the active phase, which enables a reversible facile structural change that facilitates the chemical reactions without breaking the scaffold of the electrocatalysts. The single-crystal nanocube electrode exhibits stable, continuous oxygen evolution for >1,000 h. This robust stability is attributed to the complementary nature of defect-free single-crystal electrocatalyst and the reversible adapting layer.

Exploration of a Novel Persistent Reversal of Pathological Pain: Mechanisms and Mediators

DTIC Science & Technology

2015-04-01

ability of a single IT ATL313 dose to reverse neuropathic pain from traumatic peripheral neuropathy . Milestone 2 is complete. We determined that 1 pmol...cord injury; to prevent and reverse neuropathic pain from inflammatory peripheral neuropathy following either IT or peri-sciatic nerve ( peripheral ...ATL313 can reverse neuropathic pain from inflammatory peripheral neuropathy following either IT or peri-sciatic nerve ( peripheral ) injections. We also

Observing the Heterogeneous Electro-redox of Individual Single-Layer Graphene Sheets.

PubMed

Chen, Tao; Zhang, Yuwei; Xu, Weilin

2016-09-27

Electro-redox-induced heterogeneous fluorescence of an individual single-layer graphene sheet was observed in real time by a total internal reflection fluorescence microscope. It was found that the fluorescence intensity of an individual sheet can be tuned reversibly by applying periodic voltages to control the redox degree of graphene sheets. Accordingly, the oxidation and reduction kinetics of an individual single-layer graphene sheet was studied at different voltages. The electro-redox-induced reversible variation of fluorescence intensity of individual sheets indicates a reversible band gap tuning strategy. Furthermore, correlation analysis of redox rate constants on individual graphene sheets revealed a redox-induced spatiotemporal heterogeneity or dynamics of graphene sheets. The observed controllable redox kinetics can rationally guide the precise band gap tuning of individual graphene sheets and then help their extensive applications in optoelectronics and devices for renewable energy.

Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities

NASA Technical Reports Server (NTRS)

Leavitt, L. D.; Burley, J. R., II

1985-01-01

An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0.

Energy density and energy flux in the focus of an optical vortex: reverse flux of light energy.

PubMed

Kotlyar, Victor V; Kovalev, Alexey A; Nalimov, Anton G

2018-06-15

Using the Richards-Wolf formulas for an arbitrary circularly polarized optical vortex with an integer topological charge m, we obtain explicit expressions for all components of the electric and magnetic field strength vectors near the focus, as well as expressions for the intensity (energy density) and for the energy flux (components of the Poynting vector) in the focal plane of an aplanatic optical system. For m=2, from the obtained expressions it follows that the energy flux near the optical axis propagates in the reversed direction, rotating along a spiral around the optical axis. On the optical axis itself, the reversed flux is maximal and decays rapidly with the distance from the axis. For m=3, in contrast, the reversed energy flux in the focal plane is minimal (zero) on the optical axis and increases (until the first ring of the light intensity) as a squared distance from the axis.

Insight into conformational changes of a single α-helix peptide molecule through stiffness measurements

NASA Astrophysics Data System (ADS)

Kageshima, Masami; Lantz, Mark A.; Jarvis, Suzanne P.; Tokumoto, Hiroshi; Takeda, Seiji; Ptak, Arkadiusz; Nakamura, Chikashi; Miyake, Jun

2001-07-01

Stiffness variations during the conformational change of a single α-helix polylysine peptide molecule were measured in a liquid environment using atomic force microscopy (AFM) with magnetic cantilever modulation. At the initial stage of the stretching process the stiffness decreased due to the breaking of hydrogen bonds and then increased due to the stretching of the helix backbone. These changes were reversible on reversal of the stretching motion. Below p K, the stiffness did not show increase on reversal, indicating that the reforming of hydrogen bonds did not take place. Conformational changes in the molecule were examined via these changes in stiffness.

One-Step and Stepwise Magnification of a BOBBED LETHAL Chromosome in DROSOPHILA MELANOGASTER

PubMed Central

Endow, Sharyn A.; Komma, Donald J.

1986-01-01

Bobbed lethal (bbl) chromosomes carry too few ribosomal genes for homozygous flies to be viable. Reversion of bbl chromosomes to bb or nearly bb + occurs under magnifying conditions at a low frequency in a single generation. These reversions occur too rapidly to be accounted for by single unequal sister chromatid exchanges and seem unlikely to be due to multiple sister strand exchanges within a given cell lineage. Analysis of several one-step revertants indicates that they are X-Y recombinant chromosomes which probably arise from X-Y recombination at bb. The addition of ribosomal genes from the Y chromosome to the bbl chromosome explains the more rapid reversion of the bbl chromosome than is permitted by single events of unequal sister chromatid exchange. Analysis of stepwise bbl magnified chromosomes, which were selected over a period of 4–9 magnifying generations, shows ribosomal gene patterns that are closely similar to each other. Similarity in rDNA pattern among stepwise magnified products of the same parental chromosome is consistent with reversion by a mechanism of unequal sister strand exchange. PMID:3095184

A Neural Circuit Model of Flexible Sensori-motor Mapping: Learning and Forgetting on Multiple Timescales

PubMed Central

Fusi, Stefano; Asaad, Wael F.; Miller, Earl K.; Wang, Xiao-Jing

2007-01-01

Summary Volitional behavior relies on the brain’s ability to remap sensory flow to motor programs whenever demanded by a changed behavioral context. To investigate the circuit basis of such flexible behavior, we have developed a biophysically-based decision-making network model of spiking neurons for arbitrary sensorimotor mapping. The model quantitatively reproduces behavioral and prefrontal single-cell data from an experiment in which monkeys learn visuo-motor associations that are reversed unpredictably from time to time. We show that when synaptic modifications occur on multiple timescales, the model behavior becomes flexible only when needed: slow components of learning usually dominate the decision process. However, if behavioral contexts change frequently enough, fast components of plasticity take over, and the behavior exhibits a quick forget-and-learn pattern. This model prediction is confirmed by monkey data. Therefore, our work reveals a scenario for conditional associative learning that is distinct from instant switching between sets of well established sensorimotor associations. PMID:17442251

Nitrogenase of Klebsiella pneumoniae. Interaction of the component proteins studied by ultracentrifugation

PubMed Central

Eady, Robert R.

1973-01-01

Sedimentation-velocity analyses of mixtures of the component proteins of nitrogenase of Klebsiella pneumoniae at a 1:1 molar ratio, showed a single peak of sedimentation coefficient (12.4S) considerably greater than that obtained for the larger (Fe+Mo-containing) protein centrifuged alone (10.4S). When the ratio exceeded 1:1 (the smaller Fe-containing protein in excess) an additional peak corresponding in sedimentation coefficient (about 4.5S) to free Fe-containing protein appeared. When proteins, which had been inactivated by exposure to air were used, no interaction occurred. Na2S2O4 at 2mm both reversed and prevented interaction between the two proteins; sedimentation coefficients corresponded to those of the proteins when centrifuged alone. These results demonstrate the formation of a complex between the nitrogenase proteins, and, together with data of activity titration curves, are consistent with the formulation of the nitrogenase complex of K. pneumoniae as (Fe-containing protein)–(Fe+Mo-containing protein). ImagesFig. 1. PMID:4589392

A neural circuit model of flexible sensorimotor mapping: learning and forgetting on multiple timescales.

PubMed

Fusi, Stefano; Asaad, Wael F; Miller, Earl K; Wang, Xiao-Jing

2007-04-19

Volitional behavior relies on the brain's ability to remap sensory flow to motor programs whenever demanded by a changed behavioral context. To investigate the circuit basis of such flexible behavior, we have developed a biophysically based decision-making network model of spiking neurons for arbitrary sensorimotor mapping. The model quantitatively reproduces behavioral and prefrontal single-cell data from an experiment in which monkeys learn visuomotor associations that are reversed unpredictably from time to time. We show that when synaptic modifications occur on multiple timescales, the model behavior becomes flexible only when needed: slow components of learning usually dominate the decision process. However, if behavioral contexts change frequently enough, fast components of plasticity take over, and the behavior exhibits a quick forget-and-learn pattern. This model prediction is confirmed by monkey data. Therefore, our work reveals a scenario for conditional associative learning that is distinct from instant switching between sets of well-established sensorimotor associations.

A rapid method for isolation and purification of an anticoagulant from Whitmania pigra.

PubMed

Zhong, Shan; Cui, Zheng; Sakura, Naoki; Wang, Dong; Li, Jianlin; Zhai, Yan

2007-05-01

Whitmania pigra is common in China and has been used as a traditional Chinese anticoagulant medicine for years, but its effective components are unknown to scientists. In this article we report a rapid method for isolation and purification of an anticoagulant from W. pigra for the first time. An acetone-water extract of W. pigra was subjected to anion-exchange chromatography on a Sephadex DEAE A-50 column, and gel permeation chromatography on Sephadex G-25 and Sephadex LH-20 columns successively, which afforded a fraction with potent anticoagulant activity. An anticoagulant was isolated and purified from this fraction by reversed-phase high-performance liquid chromatography (RP-HPLC). It was identified as a single pure substance by RP-HPLC and sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). This component was named whitmanin and its molecular weight was determined as 8608 Da by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry (MALDI-TOF-MS). (c) 2006 John Wiley & Sons, Ltd.

Analysis of metallic nanoparticles and their ionic counterparts in complex matrix by reversed-phase liquid chromatography coupled to ICP-MS.

PubMed

Yang, Yuan; Luo, Li; Li, Hai-Pu; Wang, Qiang; Yang, Zhao-Guang; Qu, Zhi-Peng; Ding, Ru

2018-05-15

Developing quantification and characterization methodology for metallic nanoparticles (MNPs) and their ionic component in complex matrix are crucial for the evaluation of their environmental behavior and health risks to humans. In this study, reversed phase high performance liquid chromatography combined ICP-MS was established for the characterization of MNPs in complex matrix. The ionic component could be separated from NPs with the optimized parameters of aqueous mobile phase. Good linear relationship between average diameter and retention time of NPs was obtained using HPLC-ICP-MS and the size smaller than 40 nm could be determined with this method, the detected results were in accordance with TEM results. The low detection limit of AuNPs and Au(Ⅲ) (both in sub-μg/L level) showed that this method was promising for the characterization of AuNPs and Au(Ⅲ) in environmental water. The mass concentration of ionic Au(Ⅲ) in environmental water could be detected using the proposed HPLC-ICP-MS and the concentration of AuNPs was obtained by subtracting the Au(Ⅲ) concentration from the total Au (The concentration of total Au was detected by ICP-MS after microwave digestion). Furthermore this proposed HPLC-ICP-MS method and single particle-ICPMS (SP-ICP-MS) was used for the analysis of the Ag speciation in commercial antibacterial products. Copyright © 2018 Elsevier B.V. All rights reserved.

Functionally independent components of the late positive event-related potential during visual spatial attention.

PubMed

Makeig, S; Westerfield, M; Jung, T P; Covington, J; Townsend, J; Sejnowski, T J; Courchesne, E

1999-04-01

Human event-related potentials (ERPs) were recorded from 10 subjects presented with visual target and nontarget stimuli at five screen locations and responding to targets presented at one of the locations. The late positive response complexes of 25-75 ERP average waveforms from the two task conditions were simultaneously analyzed with Independent Component Analysis, a new computational method for blindly separating linearly mixed signals. Three spatially fixed, temporally independent, behaviorally relevant, and physiologically plausible components were identified without reference to peaks in single-channel waveforms. A novel frontoparietal component (P3f) began at approximately 140 msec and peaked, in faster responders, at the onset of the motor command. The scalp distribution of P3f appeared consistent with brain regions activated during spatial orienting in functional imaging experiments. A longer-latency large component (P3b), positive over parietal cortex, was followed by a postmotor potential (Pmp) component that peaked 200 msec after the button press and reversed polarity near the central sulcus. A fourth component associated with a left frontocentral nontarget positivity (Pnt) was evoked primarily by target-like distractors presented in the attended location. When no distractors were presented, responses of five faster-responding subjects contained largest P3f and smallest Pmp components; when distractors were included, a Pmp component appeared only in responses of the five slower-responding subjects. Direct relationships between component amplitudes, latencies, and behavioral responses, plus similarities between component scalp distributions and regional activations reported in functional brain imaging experiments suggest that P3f, Pmp, and Pnt measure the time course and strength of functionally distinct brain processes.

Multilevel, multicomponent microarchitectures of vertically-aligned carbon nanotubes for diverse applications.

PubMed

Qu, Liangti; Vaia, Rich A; Dai, Liming

2011-02-22

A simple multiple contact transfer technique has been developed for controllable fabrication of multilevel, multicomponent microarchitectures of vertically aligned carbon nanotubes (VA-CNTs). Three dimensional (3-D) multicomponent micropatterns of aligned single-walled carbon nanotubes (SWNTs) and multiwalled carbon nanotubes (MWNTs) have been fabricated, which can be used to develop a newly designed touch sensor with reversible electrical responses for potential applications in electronic devices, as demonstrated in this study. The demonstrated dependence of light diffraction on structural transfiguration of the resultant CNT micropattern also indicates their potential for optical devices. Further introduction of various components with specific properties (e.g., ZnO nanorods) into the CNT micropatterns enabled us to tailor such surface characteristics as wettability and light response. Owing to the highly generic nature of the multiple contact transfer strategy, the methodology developed here could provide a general approach for interposing a large variety of multicomponent elements (e.g., nanotubes, nanorods/wires, photonic crystals, etc.) onto a single chip for multifunctional device applications.

Infrared spectroscopic near-field mapping of single nanotransistors.

PubMed

Huber, A J; Wittborn, J; Hillenbrand, R

2010-06-11

We demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) for infrared (IR) spectroscopic material recognition in state-of-the-art semiconductor devices. In particular, we employ s-SNOM for imaging of industrial CMOS transistors with a resolution better than 20 nm, which allows for the first time IR spectroscopic recognition of amorphous SiO(2) and Si(3)N(4) components in a single transistor device. The experimentally recorded near-field spectral signature of amorphous SiO(2) shows excellent agreement with model calculations based on literature dielectric values, verifying that the characteristic near-field contrasts of SiO(2) stem from a phonon-polariton resonant near-field interaction between the probing tip and the SiO(2) nanostructures. Local material recognition by s-SNOM in combination with its capabilities of contact-free and non-invasive conductivity- and strain-mapping makes IR near-field microscopy a versatile metrology technique for nanoscale material characterization and semiconductor device analysis with application potential in research and development, failure analysis and reverse engineering.

Apicobasal domain identities of expanding tubular membranes depend on glycosphingolipid biosynthesis.

PubMed

Zhang, Hongjie; Abraham, Nessy; Khan, Liakot A; Hall, David H; Fleming, John T; Göbel, Verena

2011-09-18

Metazoan internal organs are assembled from polarized tubular epithelia that must set aside an apical membrane domain as a lumenal surface. In a global Caenorhabditis elegans tubulogenesis screen, interference with several distinct fatty-acid-biosynthetic enzymes transformed a contiguous central intestinal lumen into multiple ectopic lumens. We show that multiple-lumen formation is caused by apicobasal polarity conversion, and demonstrate that in situ modulation of lipid biosynthesis is sufficient to reversibly switch apical domain identities on growing membranes of single post-mitotic cells, shifting lumen positions. Follow-on targeted lipid-biosynthesis pathway screens and functional genetic assays were designed to identify a putative single causative lipid species. They demonstrate that fatty-acid biosynthesis affects polarity through sphingolipid synthesis, and reveal ceramide glucosyltransferases (CGTs) as end-point biosynthetic enzymes in this pathway. Our findings identify glycosphingolipids, CGT products and obligate membrane lipids, as critical determinants of in vivo polarity and indicate that they sort new components to the expanding apical membrane.

Apicobasal domain identities of expanding tubular membranes depend on glycosphingolipid biosynthesis

PubMed Central

Zhang, Hongjie; Abraham, Nessy; Khan, Liakot A.; Hall, David H.; Fleming, John T.; Gobel, Verena

2011-01-01

Metazoan internal organs are assembled from polarized tubular epithelia that must set aside an apical membrane domain as a lumenal surface. In a global Caenorhabditis elegans tubulogenesis screen, interference with several distinct fatty-acid-biosynthetic enzymes transformed a contiguous central intestinal lumen into multiple ectopic lumens. We show that multiple-lumen formation is caused by apicobasal polarity conversion, and demonstrate that in situ modulation of lipid biosynthesis is sufficient to reversibly switch apical domain identities on growing membranes of single postmitotic cells, shifting lumen positions. Follow-on targeted lipid-biosynthesis pathway screens and functional genetic assays were designed to identify a putative single causative lipid species. They demonstrate that fatty-acid biosynthesis affects polarity via sphingolipid synthesis, and reveal ceramideglucosyltransferases (CGTs) as endpoint biosynthetic enzymes in this pathway. Our findings identify glycosphingolipids (GSLs), CGT products and obligate membrane lipids, as critical determinants of in vivo polarity and suggest they sort new components to the expanding apical membrane. PMID:21926990

Complementary Approaches to Existing Target Based Drug Discovery for Identifying Novel Drug Targets.

PubMed

Vasaikar, Suhas; Bhatia, Pooja; Bhatia, Partap G; Chu Yaiw, Koon

2016-11-21

In the past decade, it was observed that the relationship between the emerging New Molecular Entities and the quantum of R&D investment has not been favorable. There might be numerous reasons but few studies stress the introduction of target based drug discovery approach as one of the factors. Although a number of drugs have been developed with an emphasis on a single protein target, yet identification of valid target is complex. The approach focuses on an in vitro single target, which overlooks the complexity of cell and makes process of validation drug targets uncertain. Thus, it is imperative to search for alternatives rather than looking at success stories of target-based drug discovery. It would be beneficial if the drugs were developed to target multiple components. New approaches like reverse engineering and translational research need to take into account both system and target-based approach. This review evaluates the strengths and limitations of known drug discovery approaches and proposes alternative approaches for increasing efficiency against treatment.

Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory

PubMed Central

Fisher, Kent A. G.; England, Duncan G.; MacLean, Jean-Philippe W.; Bustard, Philip J.; Resch, Kevin J.; Sussman, Benjamin J.

2016-01-01

The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion. PMID:27045988

Frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory.

PubMed

Fisher, Kent A G; England, Duncan G; MacLean, Jean-Philippe W; Bustard, Philip J; Resch, Kevin J; Sussman, Benjamin J

2016-04-05

The spectral manipulation of photons is essential for linking components in a quantum network. Large frequency shifts are needed for conversion between optical and telecommunication frequencies, while smaller shifts are useful for frequency-multiplexing quantum systems, in the same way that wavelength division multiplexing is used in classical communications. Here we demonstrate frequency and bandwidth conversion of single photons in a room-temperature diamond quantum memory. Heralded 723.5 nm photons, with 4.1 nm bandwidth, are stored as optical phonons in the diamond via a Raman transition. Upon retrieval from the diamond memory, the spectral shape of the photons is determined by a tunable read pulse through the reverse Raman transition. We report central frequency tunability over 4.2 times the input bandwidth, and bandwidth modulation between 0.5 and 1.9 times the input bandwidth. Our results demonstrate the potential for diamond, and Raman memories in general, as an integrated platform for photon storage and spectral conversion.

Detection of bacteria in platelet concentrates prepared from spiked single donations using cultural and molecular genetic methods.

PubMed

Störmer, M; Cassens, U; Kleesiek, K; Dreier, J

2007-02-01

Bacteria show differences in their growth kinetics depending on the type of blood component. On to storage at 22 degrees C, platelet concentrates (PCs) seem to be more prone to bacterial multiplication than red cell concentrates. Knowledge of the potential for bacterial proliferation in blood components, which are stored at a range of temperatures, is essential before considering implementation of a detection strategy. The efficacy of bacterial detection was determined, using real-time reverse transcriptase-polymerase chain reaction (RT-PCR), following bacterial growth in blood components obtained from a deliberately contaminated whole-blood (WB) unit. Cultivation was used as the reference method. WB was spiked with 2 colony-forming units mL(-1)Staphylococcus epidermidis or Klebsiella pneumoniae, kept for 15 h at room temperature and component preparation was processed. Samples were drawn, at intervals throughout the whole separation process, from each blood component. Nucleic acids were extracted using an automated high-volume extraction method. The 15-h storage revealed an insignificant increase in bacterial titre. No bacterial growth was detected in red blood cell or plasma units. K. pneumoniae showed rapid growth in the pooled PC and could be detected immediately after preparation using RT-PCR. S. epidermidis grew slowly and was detected 24 h after separation. These experiments show that sampling is indicative at 24 h after preparation of PCs at the earliest to minimize the sampling error.

Reversible gating of smart plasmonic molecular traps using thermoresponsive polymers for single-molecule detection

PubMed Central

Zheng, Yuanhui; Soeriyadi, Alexander H.; Rosa, Lorenzo; Ng, Soon Hock; Bach, Udo; Justin Gooding, J.

2015-01-01

Single-molecule surface-enhanced Raman spectroscopy (SERS) has attracted increasing interest for chemical and biochemical sensing. Many conventional substrates have a broad distribution of SERS enhancements, which compromise reproducibility and result in slow response times for single-molecule detection. Here we report a smart plasmonic sensor that can reversibly trap a single molecule at hotspots for rapid single-molecule detection. The sensor was fabricated through electrostatic self-assembly of gold nanoparticles onto a gold/silica-coated silicon substrate, producing a high yield of uniformly distributed hotspots on the surface. The hotspots were isolated with a monolayer of a thermoresponsive polymer (poly(N-isopropylacrylamide)), which act as gates for molecular trapping at the hotspots. The sensor shows not only a good SERS reproducibility but also a capability to repetitively trap and release molecules for single-molecular sensing. The single-molecule sensitivity is experimentally verified using SERS spectral blinking and bianalyte methods. PMID:26549539

Investigation of the 2f1-f2 and 2f2-f1 distortion product otoacoustic emissions using a computational model of the gerbil ear.

PubMed

Wen, Haiqi; Bowling, Thomas; Meaud, Julien

2018-05-19

In this work, a three-dimensional computational model of the gerbil ear is used to investigate the generation of the 2f 1 -f 2 and 2f 2 -f 1 distortion product otoacoustic emissions (DPOAEs). In order to predict both the distortion and reflection sources, cochlear roughness is modeled by introducing random inhomogeneities in the outer hair cell properties. The model was used to simulate the generation of DPOAEs in response to a two-tone stimulus for various primary stimulus levels and frequency ratios. As in published experiments, the 2f 1 -f 2 DPOAEs are mostly dominated by the distortion component while the 2f 2 -f 1 DPOAEs are dominated by the reflection component; furthermore, the influence of the levels and frequency ratio of the primaries are consistent with measurements. Analysis of the intracochlear response shows that the distortion component has the highest magnitude at all longitudinal locations for the 2f 1 -f 2 distortion product (DP) while the distortion component only dominates close to the DP best place in the case of the 2f 2 -f 1 DP. Decomposition of the intracochlear DPs into forward and reverse waves demonstrates that the 2f 1 -f 2 DP generates reverse waves for both the distortion and reflection components; however, a reverse wave is only generated for the reflection component in the case of the 2f 2 -f 1 DP. As in experiments in the gerbil, the group delay of the reflection component of the DPOAE is between 1× and 2× the forward group delay, which is consistent with the propagation of DP towards the stapes as slow reverse waves. Copyright © 2018 Elsevier B.V. All rights reserved.

Single-port access laparoscopic reversal of Hartmann operation.

PubMed

Borowski, D W; Kanakala, V; Agarwal, A K; Tabaqchali, M A; Garg, D K; Gill, T S

2011-08-01

Single-port access offers cosmetic advantages in addition to the well-recognized benefits of standard multiport laparoscopic surgery, and can be performed with the use of standard straight instruments. We describe a technique of single-port access reversal of Hartmann colostomy by use of the colostomy site for access. After routine skin preparation and laparoscopic setup, the colostomy is mobilized from its mucocutaneous border, and the anvil of a circular stapler is secured to the distal lumen. By the use of a GelPoint system with 3 or 4 trocars, the intra-abdominal adhesions are divided and the splenic flexure is mobilized to achieve sufficient access to the abdominal and pelvic cavities and proximal colonic mobility. The rectal stump is mobilized to the mid rectum, starting from the posterior mesorectal fascia around to the anterior rectal wall. A tension-free colorectal anastomosis is secured with a standard circular stapling device inserted transanally, and leak tested. The colostomy wound is closed in standard fashion. Five patients underwent single-port access reversal of Hartmann resection (4 diverticular perforations and 1 pT3N0 colon cancer), with a mean operating time of 155 (range, 137-187) minutes and a median length of stay of 3 (range, 2-11) days. There were no conversions, major surgical morbidity, or deaths. Single-port access reversal of Hartmann colostomy through the stoma site is safe, and it offers additional cosmetic advantages with no apparent additional morbidity in comparison with standard multiport surgery.

A widespread class of reverse transcriptase-related cellular genes.

PubMed

Gladyshev, Eugene A; Arkhipova, Irina R

2011-12-20

Reverse transcriptases (RTs) polymerize DNA on RNA templates. They fall into several structurally related but distinct classes and form an assemblage of RT-like enzymes that, in addition to RTs, also includes certain viral RNA-dependent RNA polymerases (RdRP) synthesizing RNA on RNA templates. It is generally believed that most RT-like enzymes originate from retrotransposons or viruses and have no specific function in the host cell, with telomerases being the only notable exception. Here we report on the discovery and properties of a unique class of RT-related cellular genes collectively named rvt. We present evidence that rvts are not components of retrotransposons or viruses, but single-copy genes with a characteristic domain structure that may contain introns in evolutionarily conserved positions, occur in syntenic regions, and evolve under purifying selection. These genes can be found in all major taxonomic groups including protists, fungi, animals, plants, and even bacteria, although they exhibit patchy phylogenetic distribution in each kingdom. We also show that the RVT protein purified from one of its natural hosts, Neurospora crassa, exists in a multimeric form and has the ability to polymerize NTPs as well as dNTPs in vitro, with a strong preference for NTPs, using Mn(2+) as a cofactor. The existence of a previously unknown class of single-copy RT-related genes calls for reevaluation of the current views on evolution and functional roles of RNA-dependent polymerases in living cells.

Dissecting and modeling zeaxanthin- and lutein-dependent nonphotochemical quenching in Arabidopsis thaliana

PubMed Central

Leuenberger, Michelle; Morris, Jonathan M.; Chan, Arnold M.; Leonelli, Lauriebeth

2017-01-01

Photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (∆pH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on Arabidopsis thaliana to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein. Measurements were performed on WT and mutant plants deficient in one or both of the xanthophylls as well as a transgenic line that accumulates lutein via an engineered lutein epoxide cycle. Changes in the response of NPQ to light acclimation in WT and mutant plants were observed between two successive light acclimation cycles, suggesting that the character of the rapid and reversible response of NPQ in fully dark-acclimated plants is substantially different from in conditions plants are likely to experience caused by changes in light intensity during daylight. Mathematical models of the response of zeaxanthin- and lutein-dependent reversible NPQ were constructed that accurately describe the observed differences between the light acclimation periods. Finally, the WT response of NPQ was reconstructed from isolated components present in mutant plants with a single common scaling factor, which enabled deconvolution of the relative contributions of zeaxanthin- and lutein-dependent NPQ. PMID:28652334

Pneumatic Control Device for the Pershing 2 Adaption Kit

DTIC Science & Technology

1979-03-14

forward force to main- tain a pressure seal (this, versus an-I6-to 25 pound maximum reverse .force component due to pressure). In all probability, initial...stem forward force to main- tain a pressure seal (this, versus an 48-to-25-pound maximum " reverse.force, component due-topressue). In-all probability...PII Li L! Ramn Eniern Inc Contrato . 2960635 GAS GENERATOR COMPATIBILITY U TEST REPORT 1.j Requirement s The requirements for the Pershing II, Phase I

Character Reversal in Children: The Prominent Role of Writing Direction

ERIC Educational Resources Information Center

Fischer, Jean-Paul

2017-01-01

Recent research has established that 5- to 6-year-old typically developing children in a left-right writing culture spontaneously reverse left-oriented characters (e.g., they write a [reversed J] instead of J) when they write single characters. Thus, children seem to implicitly apply a right-writing rule (RWR: see Fischer & Koch, 2016a). In…

Time-reversal-symmetric single-photon wave packets for free-space quantum communication.

PubMed

Trautmann, N; Alber, G; Agarwal, G S; Leuchs, G

2015-05-01

Readout and retrieval processes are proposed for efficient, high-fidelity quantum state transfer between a matter qubit, encoded in the level structure of a single atom or ion, and a photonic qubit, encoded in a time-reversal-symmetric single-photon wave packet. They are based on controlling spontaneous photon emission and absorption of a matter qubit on demand in free space by stimulated Raman adiabatic passage. As these processes do not involve mode selection by high-finesse cavities or photon transport through optical fibers, they offer interesting perspectives as basic building blocks for free-space quantum-communication protocols.

Voltage control of magnetic single domains in Ni discs on ferroelectric BaTiO3

NASA Astrophysics Data System (ADS)

Ghidini, M.; Zhu, B.; Mansell, R.; Pellicelli, R.; Lesaine, A.; Moya, X.; Crossley, S.; Nair, B.; Maccherozzi, F.; Barnes, C. H. W.; Cowburn, R. P.; Dhesi, S. S.; Mathur, N. D.

2018-06-01

For 1 µm-diameter Ni discs on a BaTiO3 substrate, the local magnetization direction is determined by ferroelectric domain orientation as a consequence of growth strain, such that single-domain discs lie on single ferroelectric domains. On applying a voltage across the substrate, ferroelectric domain switching yields non-volatile magnetization rotations of 90°, while piezoelectric effects that are small and continuous yield non-volatile magnetization reversals that are non-deterministic. This demonstration of magnetization reversal without ferroelectric domain switching implies reduced fatigue, and therefore represents a step towards applications.

Improved particle confinement in transition from multiple-helicity to quasi-single-helicity regimes of a reversed-field pinch.

PubMed

Frassinetti, L; Predebon, I; Koguchi, H; Yagi, Y; Hirano, Y; Sakakita, H; Spizzo, G; White, R B

2006-10-27

The quasi-single-helicity (QSH) state of a reversed-field pinch (RFP) plasma is a regime in which the RFP configuration can be sustained by a dynamo produced mainly by a single tearing mode and in which a helical structure with well-defined magnetic flux surfaces arises. In this Letter, we show that spontaneous transitions to the QSH regime enhance the particle confinement. This improvement is originated by the simultaneous and cooperative action of the increase of the magnetic island and the reduction of the magnetic stochasticity.

Two-step transition towards the reversibility region in Bi2Sr2CaCu2O8-δ single crystals

NASA Astrophysics Data System (ADS)

Pastoriza, H.; de La Cruz, F.; Mitzi, D. B.; Kapitulnik, A.

1992-10-01

We have performed magnetization measurements on Bi2Sr2CaCu2O8-δ single crystals in the c^ crystallographic direction for fields from 2 Oe up to 700 Oe. The results strongly suggest that the reversible thermodynamic region is achieved after the vortex flux structure shows an abrupt transition at a temperature lower than that determined by the irreversibility line.

TNT Metabolites in Animal Tissues

DTIC Science & Technology

1991-06-01

bonded to the silica surface contained both a C18 (reversed-phase function) and a secondary amine (anioni exchange function) incorporated into a single ...contains both a C18, (reversed-phase function) and a secondary amine, (anion exchange function) incorporated into a single ligand in a 1:1 ratio. The...and store at 4°C. 4. Dosing of Mice with [14CITNT Young adult mice (Swiss Webster outbred strain) of both sexes weighing approximately 30 grams each

A microfluidic approach to parallelized transcriptional profiling of single cells.

PubMed

Sun, Hao; Olsen, Timothy; Zhu, Jing; Tao, Jianguo; Ponnaiya, Brian; Amundson, Sally A; Brenner, David J; Lin, Qiao

2015-12-01

The ability to correlate single-cell genetic information with cellular phenotypes is of great importance to biology and medicine, as it holds the potential to gain insight into disease pathways that is unavailable from ensemble measurements. We present a microfluidic approach to parallelized, rapid, quantitative analysis of messenger RNA from single cells via RT-qPCR. The approach leverages an array of single-cell RT-qPCR analysis units formed by a set of parallel microchannels concurrently controlled by elastomeric pneumatic valves, thereby enabling parallelized handling and processing of single cells in a drastically simplified operation procedure using a relatively small number of microvalves. All steps for single-cell RT-qPCR, including cell isolation and immobilization, cell lysis, mRNA purification, reverse transcription and qPCR, are integrated on a single chip, eliminating the need for off-chip manual cell and reagent transfer and qPCR amplification as commonly used in existing approaches. Additionally, the approach incorporates optically transparent microfluidic components to allow monitoring of single-cell trapping without the need for molecular labeling that can potentially alter the targeted gene expression and utilizes a polycarbonate film as a barrier against evaporation to minimize the loss of reagents at elevated temperatures during the analysis. We demonstrate the utility of the approach by the transcriptional profiling for the induction of the cyclin-dependent kinase inhibitor 1a and the glyceraldehyde 3-phosphate dehydrogenase in single cells from the MCF-7 breast cancer cell line. Furthermore, the methyl methanesulfonate is employed to allow measurement of the expression of the genes in individual cells responding to a genotoxic stress.

Toxic metals distribution in different components of Pakistani and imported cigarettes by electrothermal atomic absorption spectrometer.

PubMed

Kazi, T G; Jalbani, N; Arain, M B; Jamali, M K; Afridi, H I; Sarfraz, R A; Shah, A Q

2009-04-15

It was extensively investigated that a significant flux of toxic metals, along with other toxins, reaches the lungs through smoking. In present study toxic metals (TMs) (Al, Cd, Ni and Pb) were determined in different components of Pakistani local branded and imported cigarettes, including filler tobacco (FT), filter (before and after normal smoking by a single volunteer) and ash by electrothermal atomic absorption spectrometer (ETAAS). Microwave-assisted digestion method was employed. The validity and accuracy of methodology were checked by using certified sample of Virginia tobacco leaves (ICHTJ-cta-VTL-2). The percentages (%) of TMs in different components of cigarette were calculated with respect to their total contents in FT of all branded cigarettes before smoking, while smoke concentration has been calculated by subtracting the filter and ash contents from the filler tobacco content of each branded cigarette. The highest percentage (%) of Al was observed in ash of all cigarettes, with range 97.3-99.0%, while in the case of Cd, a reverse behaviour was observed, as a range of 15.0-31.3% of total contents were left in the ash of all branded cigarettes understudy.

Enhanced electrocaloric cooling in ferroelectric single crystals by electric field reversal

NASA Astrophysics Data System (ADS)

Ma, Yang-Bin; Novak, Nikola; Koruza, Jurij; Yang, Tongqing; Albe, Karsten; Xu, Bai-Xiang

2016-09-01

An improved thermodynamic cycle is validated in ferroelectric single crystals, where the cooling effect of an electrocaloric refrigerant is enhanced by applying a reversed electric field. In contrast to the conventional adiabatic heating or cooling by on-off cycles of the external electric field, applying a reversed field is significantly improving the cooling efficiency, since the variation in configurational entropy is increased. By comparing results from computer simulations using Monte Carlo algorithms and experiments using direct electrocaloric measurements, we show that the electrocaloric cooling efficiency can be enhanced by more than 20% in standard ferroelectrics and also relaxor ferroelectrics, like Pb (Mg1 /3 /Nb2 /3)0.71Ti0.29O3 .

Reversible binding kinetics of a cytoskeletal protein at the erythrocyte submembrane.

PubMed Central

Stout, A. L.; Axelrod, D.

1994-01-01

Reversible binding among components of the cellular submembrane cytoskeleton and reversible binding of some of these components with the plasma membrane likely play a role in nonelastic morphological changes and mechanoplastic properties of cells. However, relatively few studies have been devoted to investigating directly the kinetic aspects of the interactions of individual components of the membrane skeleton with the membrane. The experiments described here investigated whether one component of the erythrocyte membrane cytoskeleton, protein 4.1, binds to its sites on the membrane reversibly and if so, whether the different 4.1-binding sites display distinct kinetic behavior. Protein 4.1 is known to stabilize the membrane and to mediate the attachment of spectrin filaments to the membrane. Protein 4.1 previously has been shown to bind to integral membrane proteins band 3, glycophorin C, and to negatively charged phospholipids. To examine the kinetic rates of dissociation of carboxymethyl fluorescein-labeled 4.1 (CF-4.1) to the cytofacial surface of erythrocyte membrane, a special preparation of hemolyzed erythrocyte ghosts was used, in which the ghosts became flattened on a glass surface and exposed their cytofacial surfaces to the solution through a membrane rip in a distinctive characteristic pattern. This preparation was examined by the microscopy technique of total internal reflection/fluorescence recovery after photobleaching (TIR/FRAP). Four different treatments were employed to help identify which membrane binding sites gave rise to the multiplicity of observed kinetic rates. The first treatment, the control, stripped off the native spectrin, actin, 4.1, and ankyrin. About 60% of the CF-4.1 bound to this control binded irreversibly (dissociation time > 20 min), but the remaining approximately 40% binded reversibly with a range of residency times averaging approximately 3 s. The second treatment subjected these stripped membranes to trypsin, which presumably removed most of the band 3. CF-4.1 binded significantly less to these trypsinized membranes and most of the decrease was a loss of the irreversibly binding sites. The third treatment simply preserved the native 4.1 and ankyrin. CF-4.1 binded less to this sample too, and the loss involved both the irreversible and reversible sites. The fourth treatment blocked the gycophorin C sites on the native 4.1-stripped membranes with an antibody. CF-4.1 again binded less to this sample than to a nonimmune serum control, and almost all of the decrease is a loss of irreversible sites. These rest suggest that 1) protein 4.1 binds to membrane or submembrane sites at least in part reversibly ; 2) the most reversible sites are probably not proteinaceous and not glycophorin C, but possibly are phospholipids (especially phosphatidylserine); and 3) TIWRFRAP can successfully examine the fast reversible dynamics of cytoskeletal components binding to biological membranes. Images FIGURE 2 FIGURE 3 FIGURE 4 PMID:7811947

Staggering the dose of sugammadex lowers risks for severe emergence cough: a randomized control trial.

PubMed

P S, Loh; Miskan, M M; Y Z, Chin; Zaki, R A

2017-10-11

Cough on emergence has been reported as a common adverse reaction with sugammadex reversal. We investigated if staggering the dose of sugammadex will reduce emergence cough in a single-center, randomized, double-blinded study. A hundred and twenty ASA 1-3 adults were randomly reversed with 1 mg/kg sugammadex prior to extubation followed by another 1 mg/kg immediately after extubation (staggered group), single dose of 2 mg/kg sugammadex (single bolus group) or neostigmine 0.02 mg/kg with glycopyrrolate (neostigmine group). We found 70% of patients (n = 28) reversed with single boluses of sugammadex had Grade 3 emergence cough compared to 12.5% (n = 5) in the staggered sugammadex group and 17.5% (n = 7) in the neostigmine group (p < 0.001). Besides cough, emergence agitation also appeared highest in the single bolus sugammadex group (n = 14, 35%, p = 0.005). On the other hand, staggering sugammadex lowered risks of developing severe cough (RR 0.2, p < 0.001) and agitation (RR 0.43, p = 0.010) on emergence in addition to cough (RR 0.25, p = 0.039) and early sore throat (RR 0.70, p = 0.036) in the post-anesthetic care unit. The risks for severe emergence cough (RR 0.86, p = 0.762), severe cough in the post-anesthetic care unit (RR 1.0, p = 1.000) and sore throat (RR 1.17, p = 0.502) were also not different between the staggered sugammadex group and control given neostigmine. In terms of timing, there was no delay in time taken from discontinuing anesthetic agents to reversal and extubation if sugammadex was staggered (emergence time 6.0 ± 3.2 s, p = 0.625 and reversal time 6.5 ± 3.5, p = 0.809). Staggering the dose of sugammadex for reversal will effectively decrease common emergence and early postoperative complications. ANZCTR Number ACTRN12616000116426 . Retrospectively registered on 2nd February 2016.

Paleomagnetism and geochronological studies on a 450 km long 2216 Ma dyke from the Dharwar craton, southern India

NASA Astrophysics Data System (ADS)

Nagaraju, E.; Parashuramulu, V.; Kumar, Anil; Srinivas Sarma, D.

2018-01-01

Paleomagnetic and geochronological studies were carried out on a ∼ 450 km long (from 17 sites) N-S striking Paleoproterozoic dyke swarm exposed along a natural crustal cross section of about 10 km (increasing from North to South) in the Dharwar Craton, to study the characteristics of paleomagnetism and geochronology in vertical dimension. U-Pb/Pb-Pb dating on baddeleyite gives a crystallisation age of 2216.0 ± 0.9 Ma for long dyke AKLD. Paleomagnetic data from this well dated ∼ 2216 Ma dyke swarm in Dharwar Craton are of excellent quality. High coercivity and high blocking temperature components are carried by single domain magnetite and show dual polarity remanence directions. Combined normal and reverse polarity remanences on AKLD and other N-S dykes define the most reliable paleomagnetic pole for ∼ 2216 Ma at latitude 36°S and longitude 312°E (A95 = 7°). Though paleomagnetic data is unavailable on other N-S dykes below the Cuddapah basin, high precision geochronology suggest that they are of similar age within errors. Though there is a variation in the crustal depth of Dharwar craton from north to south, consistent Pb-Pb/U-Pb baddeleyite geochronology and paleomagnetic studies along the AKLD established its continuity and preservation along its entire strike length. The virtual geomagnetic poles of these sites confirm a stable remanence and are almost identical to the previously reported paleomagnetic pole and also supported by positive reversal test. Positive paleomagnetic reversal test on these dykes signify that the remanent magnetization is primary and formed during initial cooling of the intrusions. Updated apparent polar wander path of Dharwar craton indicates relatively low drift rate during 2.21-2.08 Ga interval. Magnetogranulometry and SEM studies show that remanent magnetization in this dyke was carried by single domain magnetite residing within silicate minerals.

Analytical models for coupling reliability in identical two-magnet systems during slow reversals

NASA Astrophysics Data System (ADS)

Kani, Nickvash; Naeemi, Azad

2017-12-01

This paper follows previous works which investigated the strength of dipolar coupling in two-magnet systems. While those works focused on qualitative analyses, this manuscript elucidates reversal through dipolar coupling culminating in analytical expressions for reversal reliability in identical two-magnet systems. The dipolar field generated by a mono-domain magnetic body can be represented by a tensor containing both longitudinal and perpendicular field components; this field changes orientation and magnitude based on the magnetization of neighboring nanomagnets. While the dipolar field does reduce to its longitudinal component at short time-scales, for slow magnetization reversals, the simple longitudinal field representation greatly underestimates the scope of parameters that ensure reliable coupling. For the first time, analytical models that map the geometric and material parameters required for reliable coupling in two-magnet systems are developed. It is shown that in biaxial nanomagnets, the x ̂ and y ̂ components of the dipolar field contribute to the coupling, while all three dimensions contribute to the coupling between a pair of uniaxial magnets. Additionally, the ratio of the longitudinal and perpendicular components of the dipolar field is also very important. If the perpendicular components in the dipolar tensor are too large, the nanomagnet pair may come to rest in an undesirable meta-stable state away from the free axis. The analytical models formulated in this manuscript map the minimum and maximum parameters for reliable coupling. Using these models, it is shown that there is a very small range of material parameters which can facilitate reliable coupling between perpendicular-magnetic-anisotropy nanomagnets; hence, in-plane nanomagnets are more suitable for coupled systems.

Magnetostratigraphy of Early Middle Toarcian expanded sections from the Iberian Range (central Spain)

NASA Astrophysics Data System (ADS)

Osete, María-Luisa; Gialanella, Paola-Romana; Gómez, Juan J.; Villalaín, Juan J.; Goy, Antonio; Heller, Friedrich

2007-07-01

The magnetostratigraphy of the Lower-Middle Toarcian has been established in two well-dated stratigraphically expanded sections: the Sierra Palomera and the Ariño sections, located in the Iberian Range, in central-eastern Spain. Two magnetisation components could be isolated by thermal cleaning: a secondary syntectonic component of always normal polarity unblocking at intermediate temperatures up to 450 °C/475 °C (A component) and a high temperature unblocking component up to 575 °C (B component). The B component passes fold and reversal tests and is considered the characteristic remanent magnetisation of primary origin. The first Toarcian palaeomagnetic pole for Iberia has been obtained: Plat = 77.4°, Plon = 241.3°E (dm = 5.4° dp = 6.0°). Five pairs of normal and reversed polarity zones were calibrated to regional ammonite subzones. The pattern can be calibrated to other Toarcian magnetostratigraphic studies, but provides a more detailed biostratigraphic framework. A refined magnetic polarity time scale is proposed for the Lower-Middle Toarcian.

Outcomes Study of the TM Reverse Shoulder System Used in Primary or Revision Reverse Total Shoulder Arthroplasty

ClinicalTrials.gov

2018-02-13

Osteoarthritis; Rheumatoid Arthritis; Post-traumatic Arthritis; Ununited Humeral Head Fracture; Irreducible 3-and 4-part Proximal Humeral Fractures; Avascular Necrosis; Gross Rotator Cuff Deficiency; Failed Total Shoulder Arthroplasty (Both Glenoid and Humeral Components Require Revision

Deciphering the molecular mechanisms underlying sea urchin reversible adhesion: A quantitative proteomics approach.

PubMed

Lebesgue, Nicolas; da Costa, Gonçalo; Ribeiro, Raquel Mesquita; Ribeiro-Silva, Cristina; Martins, Gabriel G; Matranga, Valeria; Scholten, Arjen; Cordeiro, Carlos; Heck, Albert J R; Santos, Romana

2016-04-14

Marine bioadhesives have unmatched performances in wet environments, being an inspiration for biomedical applications. In sea urchins specialized adhesive organs, tube feet, mediate reversible adhesion, being composed by a disc, producing adhesive and de-adhesive secretions, and a motile stem. After tube foot detachment, the secreted adhesive remains bound to the substratum as a footprint. Sea urchin adhesive is composed by proteins and sugars, but so far only one protein, Nectin, was shown to be over-expressed as a transcript in tube feet discs, suggesting its involvement in sea urchin adhesion. Here we use high-resolution quantitative mass-spectrometry to perform the first study combining the analysis of the differential proteome of an adhesive organ, with the proteome of its secreted adhesive. This strategy allowed us to identify 163 highly over-expressed disc proteins, specifically involved in sea urchin reversible adhesion; to find that 70% of the secreted adhesive components fall within five protein groups, involved in exocytosis and microbial protection; and to provide evidences that Nectin is not only highly expressed in tube feet discs but is an actual component of the adhesive. These results give an unprecedented insight into the molecular mechanisms underlying sea urchin adhesion, and opening new doors to develop wet-reliable, reversible, and ecological biomimetic adhesives. Sea urchins attach strongly but in a reversible manner to substratum, being a valuable source of inspiration for industrial and biomedical applications. Yet, the molecular mechanisms governing reversible adhesion are still poorly studied delaying the engineering of biomimetic adhesives. We used the latest mass spectrometry techniques to analyze the differential proteome of an adhesive organ and the proteome of its secreted adhesive, allowing us to uncover the key players in sea urchin reversible adhesion. We demonstrate, that Nectin, a protein previously pointed out as potentially involved in sea urchin adhesion, is not only highly expressed in tube feet discs, but is a genuine component of the secreted adhesive. Copyright © 2016 Elsevier B.V. All rights reserved.

Digit Reversal in Children's Writing: A Simple Theory and Its Empirical Validation

ERIC Educational Resources Information Center

Fischer, Jean-Paul

2013-01-01

This article presents a simple theory according to which the left-right reversal of single digits by 5- and 6-year-old children is mainly due to the application of an implicit right-writing or -orienting rule. A number of nontrivial predictions can be drawn from this theory. First, left-oriented digits (1, 2, 3, 7, and 9) will be reversed more…

The contributions of premating and postmating selection episodes to total selection in sex-role-reversed Gulf pipefish.

PubMed

Rose, Emily; Paczolt, Kimberly A; Jones, Adam G

2013-09-01

Empirical studies of sexual selection often focus on events occurring either before or after mating but rarely both and consequently may fail to discern the relative magnitudes and interactions of premating and postmating episodes of selection. Here, we simultaneously quantify premating and postmating selection in the sex-role-reversed Gulf pipefish by using a microsatellite-based analysis of parentage in experimental populations. Female pipefish exhibited an opportunity for selection (I) of 1.64, which was higher than that of males (0.35). Decompositions of I and the selection differential on body size showed that over 95% of the selection on females arose from the premating phase. We also found evidence for a trade-off between selection phases, where multiply mating females had significantly lower offspring survivorship compared to singly mated females. In males, variance in relative fitness arose mainly from the number of eggs received per copulation and a small number of males who failed to mate. Overall, our study exemplifies a general approach for the decomposition of total selection into premating and postmating phases to understand the interplay among components of natural and sexual selection that conspire to shape sexually selected traits.

Time reversal of arbitrary photonic temporal modes via nonlinear optical frequency conversion

NASA Astrophysics Data System (ADS)

Raymer, Michael G.; Reddy, Dileep V.; van Enk, Steven J.; McKinstrie, Colin J.

2018-05-01

Single-photon wave packets can carry quantum information between nodes of a quantum network. An important general operation in photon-based quantum information systems is ‘blind’ reversal of a photon’s temporal wave packet envelope, that is, the ability to reverse an envelope without knowing the temporal state of the photon. We present an all-optical means for doing so, using nonlinear-optical frequency conversion driven by a short pump pulse. The process used may be sum-frequency generation or four-wave Bragg scattering. This scheme allows for quantum operations such as a temporal-mode parity sorter. We also verify that the scheme works for arbitrary states (not only single-photon ones) of an unknown wave packet.

Ultraviolet/blue light-emitting diodes based on single horizontal ZnO microrod/GaN heterojunction.

PubMed

Du, Chia-Fong; Lee, Chen-Hui; Cheng, Chao-Tsung; Lin, Kai-Hsiang; Sheu, Jin-Kong; Hsu, Hsu-Cheng

2014-01-01

We report electroluminescence (EL) from single horizontal ZnO microrod (MR) and p-GaN heterojunction light-emitting diodes under forward and reverse bias. EL spectra were composed of two blue emissions centered at 431 and 490 nm under forward biases, but were dominated by a ultraviolet (UV) emission located at 380 nm from n-ZnO MR under high reverse biases. Light-output-current characteristic of the UV emission reveals that the rate of radiative recombination is faster than that of the nonradiative recombination. Highly efficient ZnO excitonic recombination at reverse bias is caused by electrons tunneling from deep-level states near the n-ZnO/p-GaN interface to the conduction band in n-ZnO.

Descriptive Analysis of Single Subject Research Designs: 1983-2007

ERIC Educational Resources Information Center

Hammond, Diana; Gast, David L.

2010-01-01

Single subject research methodology is commonly used and cited in special education courses and journals. This article reviews the types of single subject research designs published in eight refereed journals between 1983 and 2007 used to answer applied research questions. Single subject designs were categorized as withdrawal/reversal, time…

Reverse Engineering Validation using a Benchmark Synthetic Gene Circuit in Human Cells

PubMed Central

Kang, Taek; White, Jacob T.; Xie, Zhen; Benenson, Yaakov; Sontag, Eduardo; Bleris, Leonidas

2013-01-01

Multi-component biological networks are often understood incompletely, in large part due to the lack of reliable and robust methodologies for network reverse engineering and characterization. As a consequence, developing automated and rigorously validated methodologies for unraveling the complexity of biomolecular networks in human cells remains a central challenge to life scientists and engineers. Today, when it comes to experimental and analytical requirements, there exists a great deal of diversity in reverse engineering methods, which renders the independent validation and comparison of their predictive capabilities difficult. In this work we introduce an experimental platform customized for the development and verification of reverse engineering and pathway characterization algorithms in mammalian cells. Specifically, we stably integrate a synthetic gene network in human kidney cells and use it as a benchmark for validating reverse engineering methodologies. The network, which is orthogonal to endogenous cellular signaling, contains a small set of regulatory interactions that can be used to quantify the reconstruction performance. By performing successive perturbations to each modular component of the network and comparing protein and RNA measurements, we study the conditions under which we can reliably reconstruct the causal relationships of the integrated synthetic network. PMID:23654266

Nonlinear Time-Reversal in a Wave Chaotic System

NASA Astrophysics Data System (ADS)

Frazier, Matthew; Taddese, Biniyam; Ott, Edward; Antonsen, Thomas; Anlage, Steven

2012-02-01

Time reversal mirrors are particularly simple to implement in wave chaotic systems and form the basis for a new class of sensors [1-3]. These sensors work by applying the quantum mechanical concepts of Loschmidt echo and fidelity decay to classical waves. The sensors make explicit use of time-reversal invariance and spatial reciprocity in a wave chaotic system to remotely measure the presence of small perturbations to the system. The underlying ray chaos increases the sensitivity to small perturbations throughout the volume explored by the waves. We extend our time-reversal mirror to include a discrete element with a nonlinear dynamical response. The initially injected pulse interacts with the nonlinear element, generating new frequency components originating at the element. By selectively filtering for and applying the time-reversal mirror to the new frequency components, we focus a pulse only onto the element, without knowledge of its location. Furthermore, we demonstrate transmission of arbitrary patterns of pulses to the element, creating a targeted communication channel to the exclusion of 'eavesdroppers' at other locations in the system. [1] Appl. Phys. Lett. 95, 114103 (2009) [2] J. Appl. Phys. 108, 1 (2010) [3] Acta Physica Polonica A 112, 569 (2007)

Magnetic chaos healing in the helical reversed-field pinch: indications from the volume-preserving field line tracing code NEMATO

NASA Astrophysics Data System (ADS)

Bonfiglio, D.; Veranda, M.; Cappello, S.; Chacón, L.; Spizzo, G.

2010-11-01

The emergence of a self-organized reversed-field pinch (RFP) helical regime, first shown by 3D MHD numerical simulations, has been highlighted in the RFX-mod experiment at high current operation (IP above 1 MA). In fact, a quasi-stationary helical configuration spontaneously appears, characterized by strong internal electron transport barriers. In such regime electron temperature and density become, to a very good approximation, functions of the helical flux coordinate related to the dominant helical magnetic component. In addition, this regime is diagnosed to be associated with the topological transition to a single-helical-axis (SHAx) state, achieved after the expulsion of the separatrix of the dominant mode's magnetic island. The SHAx state is theoretically predicted to be resilient to the magnetic chaos induced by secondary modes. In this paper, we present initial results of the volume-preserving field line tracing code NEMATO [Finn J M and Chacón L 2005 Phys. Plasmas 12 054503] applied to study the magnetic topology resulting from 3D MHD simulations of the RFP. First, a successful 2D verification test of the code is shown, then, initial application to a systematic study of chaos healing in the helical RFP is discussed. The separatrix disappearance is confirmed to play an essential role for chaos healing. The triggering effect of a reversed magnetic shear for the formation of ordered surfaces within magnetic chaos is also diagnosed.

Magnetic chaos healing in hte helical reversed-field pinch: indications from the volume-preserving field line tracing code NEMATO

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

Bonfiglio, Daniele; Veranda, M.; Cappello, Susanna

2010-01-01

The emergence of a self-organized reversed-field pinch (RFP) helical regime, first shown by 3D MHD numerical simulations, has been highlighted in the RFX-mod experiment at high current operation (IP above 1 MA). In fact, a quasi-stationary helical configuration spontaneously appears, characterized by strong internal electron transport barriers. In such regime electron temperature and density become, to a very good approximation, functions of the helical flux coordinate related to the dominant helical magnetic component. In addition, this regime is diagnosed to be associated with the topological transition to a single-helical-axis (SHAx) state, achieved after the expulsion of the separatrix of themore » dominant mode's magnetic island. The SHAx state is theoretically predicted to be resilient to the magnetic chaos induced by secondary modes. In this paper, we present initial results of the volume-preserving field line tracing code nemato [Finn J M and Chacon L 2005 Phys. Plasmas 12 054503] applied to study the magnetic topology resulting from 3D MHD simulations of the RFP. First, a successful 2D verification test of the code is shown, then, initial application to a systematic study of chaos healing in the helical RFP is discussed. The separatrix disappearance is confirmed to play an essential role for chaos healing. The triggering effect of a reversed magnetic shear for the formation of ordered surfaces within magnetic chaos is also diagnosed.« less

Sequence specific motor performance gains after memory consolidation in children and adolescents.

PubMed

Dorfberger, Shoshi; Adi-Japha, Esther; Karni, Avi

2012-01-01

Memory consolidation for a trained sequence of finger opposition movements, in 9- and 12-year-old children, was recently found to be significantly less susceptible to interference by a subsequent training experience, compared to that of 17-year-olds. It was suggested that, in children, the experience of training on any sequence of finger movements may affect the performance of the sequence elements, component movements, rather than the sequence as a unit; the latter has been implicated in the learning of the task by adults. This hypothesis implied a possible childhood advantage in the ability to transfer the gains from a trained to the reversed, untrained, sequence of movements. Here we report the results of transfer tests undertaken to test this proposal in 9-, 12-, and 17-year-olds after training in the finger-to-thumb opposition sequence (FOS) learning task. Our results show that the performance gains in the trained sequence partially transferred from the left, trained hand, to the untrained hand at 48-hours after a single training session in the three age-groups tested. However, there was very little transfer of the gains from the trained to the untrained, reversed, sequence performed by either hand. The results indicate sequence specific post-training gains in FOS performance, as opposed to a general improvement in performance of the individual, component, movements that comprised both the trained and untrained sequences. These results do not support the proposal that the reduced susceptibility to interference, in children before adolescence, reflects a difference in movement syntax representation after training.

Entanglement and the three-dimensionality of the Bloch ball

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

Masanes, Ll., E-mail: ll.masanes@gmail.com; Müller, M. P.; Pérez-García, D.

2014-12-15

We consider a very natural generalization of quantum theory by letting the dimension of the Bloch ball be not necessarily three. We analyze bipartite state spaces where each of the components has a d-dimensional Euclidean ball as state space. In addition to this, we impose two very natural assumptions: the continuity and reversibility of dynamics and the possibility of characterizing bipartite states by local measurements. We classify all these bipartite state spaces and prove that, except for the quantum two-qubit state space, none of them contains entangled states. Equivalently, in any of these non-quantum theories, interacting dynamics is impossible. Thismore » result reveals that “existence of entanglement” is the requirement with minimal logical content which singles out quantum theory from our family of theories.« less

Analysis of the influence of backscattered optical power over bidirectional PON links

NASA Astrophysics Data System (ADS)

Martínez, J. J.; Garcés, I.; López, A.; Villafranca, A.; Losada, M. A.

2010-05-01

Our aim is to describe the behavior of non-linear scattering effects that arise in standard single mode fiber (SMF), specifically scattering effects that propagate optical power in the reverse direction of the source signal such as Rayleigh Scattering (RS) and Brillouin Scattering (BS). For this purpose, the effects of backscattering phenomena over a bidirectional data transmission in a passive optical network (PON) scheme have been assessed. The impact of these high optical power components over reception at the optical line terminal (OLT) side has been determined when both links use the same wavelength. Bit Error Rate (BER) measurements have been performed with different transmission rates, using several techniques to mitigate the influence of backscattering over the received signal and considering cases with filtered and unfiltered BS.

A truly Lego®-like modular microfluidics platform

NASA Astrophysics Data System (ADS)

Vittayarukskul, Kevin; Lee, Abraham Phillip

2017-03-01

Ideally, a modular microfluidics platform should be simple to assemble and support 3D configurations for increased versatility. The modular building blocks should also be mass producible like electrical components. These are fundamental features of world-renowned Legos® and why Legos® inspire many existing modular microfluidics platforms. In this paper, a truly Lego®-like microfluidics platform is introduced, and its basic feasibility is demonstrated. Here, PDMS building blocks resembling 2  ×  2 Lego® bricks are cast from 3D-printed master molds. The blocks are pegged and stacked on a traditional Lego® plate to create simple, 3D microfluidic networks, such as a single basket weave. Characteristics of the platform, including reversible sealing and automatic alignment of channels, are also analyzed and discussed in detail.

Reverse engineering of an affinity-switchable molecular interaction characterized by atomic force microscopy single-molecule force spectroscopy.

PubMed

Anselmetti, Dario; Bartels, Frank Wilco; Becker, Anke; Decker, Björn; Eckel, Rainer; McIntosh, Matthew; Mattay, Jochen; Plattner, Patrik; Ros, Robert; Schäfer, Christian; Sewald, Norbert

2008-02-19

Tunable and switchable interaction between molecules is a key for regulation and control of cellular processes. The translation of the underlying physicochemical principles to synthetic and switchable functional entities and molecules that can mimic the corresponding molecular functions is called reverse molecular engineering. We quantitatively investigated autoinducer-regulated DNA-protein interaction in bacterial gene regulation processes with single atomic force microscopy (AFM) molecule force spectroscopy in vitro, and developed an artificial bistable molecular host-guest system that can be controlled and regulated by external signals (UV light exposure and thermal energy). The intermolecular binding functionality (affinity) and its reproducible and reversible switching has been proven by AFM force spectroscopy at the single-molecule level. This affinity-tunable optomechanical switch will allow novel applications with respect to molecular manipulation, nanoscale rewritable molecular memories, and/or artificial ion channels, which will serve for the controlled transport and release of ions and neutral compounds in the future.

Magnetic field manipulation of spin current in a single-molecule magnet tunnel junction with two-electron Coulomb interaction

NASA Astrophysics Data System (ADS)

Zhang, Chao; Yao, Hui; Nie, Yi-Hang; Liang, Jiu-Qing; Niu, Peng-Bin

2018-04-01

In this work, we study the generation of spin-current in a single-molecule magnet (SMM) tunnel junction with Coulomb interaction of transport electrons and external magnetic field. In the absence of field the spin-up and -down currents are symmetric with respect to the initial polarizations of molecule. The existence of magnetic field breaks the time-reversal symmetry, which leads to unsymmetrical spin currents of parallel and antiparallel polarizations. Both the amplitude and polarization direction of spin current can be controlled by the applied magnetic field. Particularly when the magnetic field increases to a certain value the spin-current with antiparallel polarization is reversed along with the magnetization reversal of the SMM. The two-electron occupation indeed enhances the transport current compared with the single-electron process. However the increase of Coulomb interaction results in the suppression of spin-current amplitude at the electron-hole symmetry point. We propose a scheme to compensate the suppression with the magnetic field.

Reversible thermosalience of 4-aminobenzonitrile.

PubMed

Alimi, Lukman O; van Heerden, Dewald P; Lama, Prem; Smith, Vincent J; Barbour, Leonard J

2018-05-31

Crystals of 4-aminobenzonitrile grown by sublimation undergo reversible thermosalient phase changes during cooling and subsequent heating. Single-crystal diffraction studies have been carried out at 20 K intervals during cooling from 300 to 100 K in order to explain the structural change that occurs.

Induction of long-lasting multi-specific CD8+ T cells by a four-component DNA-MVA/HIVA-RENTA candidate HIV-1 vaccine in rhesus macaques.

PubMed

Im, Eung-Jun; Nkolola, Joseph P; di Gleria, Kati; McMichael, Andrew J; Hanke, Tomás

2006-10-01

As a part of a long-term effort to develop vaccine against HIV-1 clade A inducing protective T cell responses in humans, we run mutually complementing studies in humans and non-human primates (NHP) with the aim to maximize vaccine immunogenicity. The candidate vaccine under development has four components, pTHr.HIVA and pTH.RENTA DNA, and modified vaccinia virus Ankara (MVA).HIVA and MVA.RENTA, delivered in a heterologous DNA prime-MVA boost regimen. While the HIVA (Gag/epitopes) components have been tested in NHP and over 300 human subjects, we plan to test in humans the RENTA (reverse transcriptase, gp41, Nef, Tat) vaccines designed to broaden HIVA-induced responses in year 2007. Here, we investigated the four-component vaccine long-term immunogenicity in Mamu-A*01-positive rhesus macaques and demonstrated that the vaccine-induced T cells were multi-specific, multi-functional, readily proliferated to recall peptides and were circulating in the peripheral blood of vaccine recipients over 1 year after vaccine administration. The consensus clade A-elicited T cells recognized 50% of tested epitope variants from other HIV-1 clades. Thus, the DNA-MVA/HIVA-RENTA vaccine induced memory T cells of desirable characteristics and similarities to those induced in humans by HIVA vaccines alone; however, single-clade vaccines may not elicit sufficiently cross-reactive responses.

Autoregressive harmonic analysis of the earth's polar motion using homogeneous international latitude service data

NASA Astrophysics Data System (ADS)

Fong Chao, B.

1983-12-01

The homogeneous set of 80-year-long (1900-1979) International Latitude Service (ILS) polar motion data is analyzed using the autoregressive method (Chao and Gilbert, 1980) which resolves and produces estimates for the complex frequency (or frequency and Q) and complex amplitude (or amplitude and phase) of each harmonic component in the data. Principal conclusion of this analysis are that (1) the ILS data support the multiple-component hypothesis of the Chandler wobble (it is found that the Chandler wobble can be adequately modeled as a linear combination of four (coherent) harmonic components, each of which represents a steady, nearly circular, prograte motion, a behavior that is inconsistent with the hypothesis of a single Chandler period excited in a temporally and/or spatially random fashion). (2) the four-component Chandler wobble model ``explains'' the apparent phase reversal during 1920-1940 and the pre-1950 empirical period-amplitude relation, (3) the annual wobble is shown to be rather stationary over the years both in amplitude and in phase and no evidence is found to support the large variations reported by earlier investigations. (4) the Markowitz wobble is found to support the large variations reported by earlier investigations. (4) the Markowitz wobble is found to be marginally retrograde and appears to have a complicated behavior which cannot be resolved because of the shortness of the data set.

Kinetics of force recovery following length changes in active skinned single fibres from rabbit psoas muscle

PubMed Central

Burton, Kevin; Simmons, Robert M; Sleep, John; Smith, David A

2006-01-01

Redevelopment of isometric force following shortening of skeletal muscle is thought to result from a redistribution of cross-bridge states. We varied the initial force and cross-bridge distribution by applying various length-change protocols to active skinned single fibres from rabbit psoas muscle, and observed the effect on the slowest phase of recovery (‘late recovery’) that follows transient changes. In response to step releases that reduced force to near zero (∼8 nm (half sarcomere)−1) or prolonged shortening at high velocity, late recovery was well described by two exponentials of approximately equal amplitude and rate constants of ∼2 s−1 and ∼9 s−1 at 5°C. When a large restretch was applied at the end of rapid shortening, recovery was accelerated by (1) the introduction of a slow falling component that truncated the rise in force, and (2) a relative increase in the contribution of the fast exponential component. The rate of the slow fall was similar to that observed after a small isometric step stretch, with a rate of 0.4–0.8 s−1, and its effects could be reversed by reducing force to near zero immediately after the stretch. Force at the start of late recovery was varied in a series of shortening steps or ramps in order to probe the effect of cross-bridge strain on force redevelopment. The rate constants of the two components fell by 40–50% as initial force was raised to 75–80% of steady isometric force. As initial force increased, the relative contribution of the fast component decreased, and this was associated with a length constant of about 2 nm. The results are consistent with a two-state strain-dependent cross-bridge model. In the model there is a continuous distribution of recovery rate constants, but two-exponential fits show that the fast component results from cross-bridges initially at moderate positive strain and the slow component from cross-bridges at high positive strain. PMID:16497718

Evolution of a Planar Wake in Adverse Pressure Gradient

NASA Technical Reports Server (NTRS)

Driver, David M.; Mateer, George G.

2016-01-01

In the interest of improving the predictability of high-lift systems at maximum lift conditions, a series of fundamental experiments were conducted to study the effects of adverse pressure gradient on a wake flow. Mean and fluctuating velocities were measured with a two-component laser-Doppler velocimeter. Data were obtained for several cases of adverse pressure gradient, producing flows ranging from no reversed flow to massively reversed flow. While the turbulent Reynolds stresses increase with increasing size of the reversed flow region, the gradient of Reynolds stress does not. Computations using various turbulence models were unable to reproduce the reversed flow.

Twenty-Five Years of Lamivudine: Current and Future Use for the Treatment of HIV-1 Infection.

PubMed

Quercia, Romina; Perno, Carlo-Federico; Koteff, Justin; Moore, Katy; McCoig, Cynthia; St Clair, Marty; Kuritzkes, Daniel

2018-06-01

Innovation in medicine is a dynamic, complex, and continuous process that cannot be isolated to a single moment in time. Anniversaries offer opportunities to commemorate crucial discoveries of modern medicine, such as penicillin (1928), polio vaccination (inactivated, 1955; oral, 1961), the surface antigen of the hepatitis B virus (1967), monoclonal antibodies (1975), and the first HIV antiretroviral drugs (zidovudine, 1987). The advent of antiretroviral drugs has had a profound effect on the progress of the epidemiology of HIV infection, transforming a terminal, irreversible disease that caused a global health crisis into a treatable but chronic disease. This result has been driven by the success of antiretroviral drug combinations that include nucleoside reverse transcriptase inhibitors such as lamivudine. Lamivudine, an L-enantiomeric analog of cytosine, potently affects HIV replication by inhibiting viral reverse transcriptase enzymes at concentrations without toxicity against human polymerases. Although lamivudine was approved more than 2 decades ago, it remains a key component of first-line therapy for HIV because of its virological efficacy and ability to be partnered with other antiretroviral agents in traditional and novel combination therapies. The prominence of lamivudine in HIV therapy is highlighted by its incorporation in recent innovative treatment strategies, such as single-tablet regimens that address challenges associated with regimen complexity and treatment adherence and 2-drug regimens being developed to mitigate cumulative drug exposure and toxicities. This review summarizes how the pharmacologic and virologic properties of lamivudine have solidified its role in contemporary HIV therapy and continue to support its use in emerging therapies.

Dissecting and modeling zeaxanthin- and lutein-dependent nonphotochemical quenching in Arabidopsis thaliana

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

Leuenberger, Michelle; Morris, Jonathan M.; Chan, Arnold M.

It is known that photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (ΔpH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on Arabidopsis thaliana to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein. Measurements were performed onmore » WT and mutant plants deficient in one or both of the xanthophylls as well as a transgenic line that accumulates lutein via an engineered lutein epoxide cycle. Changes in the response of NPQ to light acclimation in WT and mutant plants were observed between two successive light acclimation cycles, suggesting that the character of the rapid and reversible response of NPQ in fully dark-acclimated plants is substantially different from in conditions plants are likely to experience caused by changes in light intensity during daylight. Mathematical models of the response of zeaxanthin- and lutein-dependent reversible NPQ were constructed that accurately describe the observed differences between the light acclimation periods. Finally, the WT response of NPQ was reconstructed from isolated components present in mutant plants with a single common scaling factor, which enabled deconvolution of the relative contributions of zeaxanthin- and lutein-dependent NPQ.« less

Dissecting and modeling zeaxanthin- and lutein-dependent nonphotochemical quenching in Arabidopsis thaliana

DOE PAGES

Leuenberger, Michelle; Morris, Jonathan M.; Chan, Arnold M.; ...

2017-06-26

It is known that photosynthetic organisms use various photoprotective mechanisms to dissipate excess photoexcitation as heat in a process called nonphotochemical quenching (NPQ). Regulation of NPQ allows for a rapid response to changes in light intensity and in vascular plants, is primarily triggered by a pH gradient across the thylakoid membrane (ΔpH). The response is mediated by the PsbS protein and various xanthophylls. Time-correlated single-photon counting (TCSPC) measurements were performed on Arabidopsis thaliana to quantify the dependence of the response of NPQ to changes in light intensity on the presence and accumulation of zeaxanthin and lutein. Measurements were performed onmore » WT and mutant plants deficient in one or both of the xanthophylls as well as a transgenic line that accumulates lutein via an engineered lutein epoxide cycle. Changes in the response of NPQ to light acclimation in WT and mutant plants were observed between two successive light acclimation cycles, suggesting that the character of the rapid and reversible response of NPQ in fully dark-acclimated plants is substantially different from in conditions plants are likely to experience caused by changes in light intensity during daylight. Mathematical models of the response of zeaxanthin- and lutein-dependent reversible NPQ were constructed that accurately describe the observed differences between the light acclimation periods. Finally, the WT response of NPQ was reconstructed from isolated components present in mutant plants with a single common scaling factor, which enabled deconvolution of the relative contributions of zeaxanthin- and lutein-dependent NPQ.« less

Nano-encrypted Morse code: a versatile approach to programmable and reversible nanoscale assembly and disassembly.

PubMed

Wong, Ngo Yin; Xing, Hang; Tan, Li Huey; Lu, Yi

2013-02-27

While much work has been devoted to nanoscale assembly of functional materials, selective reversible assembly of components in the nanoscale pattern at selective sites has received much less attention. Exerting such a reversible control of the assembly process will make it possible to fine-tune the functional properties of the assembly and to realize more complex designs. Herein, by taking advantage of different binding affinities of biotin and desthiobiotin toward streptavidin, we demonstrate selective and reversible decoration of DNA origami tiles with streptavidin, including revealing an encrypted Morse code "NANO" and reversible exchange of uppercase letter "I" with lowercase "i". The yields of the conjugations are high (>90%), and the process is reversible. We expect this versatile conjugation technique to be widely applicable with different nanomaterials and templates.

Four-Component Catalytic Machinery: Reversible Three-State Control of Organocatalysis by Walking Back and Forth on a Track.

PubMed

Mittal, Nikita; Özer, Merve S; Schmittel, Michael

2018-04-02

A three-component supramolecular walker system is presented where a two-footed ligand (biped) walks back and forth on a tetrahedral 3D track upon the addition and removal of copper(I) ions, respectively. The addition of N-methylpyrrolidine as a catalyst to the walker system generates a four-component catalytic machinery, which acts as a three-state switchable catalytic ensemble in the presence of substrates for a conjugate addition. The copper(I)-ion-initiated walking process of the biped ligand on the track regulates the catalytic activity in three steps: ON versus int ON (intermediate ON) versus OFF. To establish the operation of the four-component catalytic machinery in a mixture of all constituents, forward and backward cycles were performed in situ illustrating that both the walking process and catalytic action are fully reversible and reproducible.

3D Printed Reversible Shape Changing Components with Stimuli Responsive Materials

PubMed Central

Mao, Yiqi; Ding, Zhen; Yuan, Chao; Ai, Shigang; Isakov, Michael; Wu, Jiangtao; Wang, Tiejun; Dunn, Martin L.; Qi, H. Jerry

2016-01-01

The creation of reversibly-actuating components that alter their shapes in a controllable manner in response to environmental stimuli is a grand challenge in active materials, structures, and robotics. Here we demonstrate a new reversible shape-changing component design concept enabled by 3D printing two stimuli responsive polymers—shape memory polymers and hydrogels—in prescribed 3D architectures. This approach uses the swelling of a hydrogel as the driving force for the shape change, and the temperature-dependent modulus of a shape memory polymer to regulate the time of such shape change. Controlling the temperature and aqueous environment allows switching between two stable configurations – the structures are relatively stiff and can carry load in each – without any mechanical loading and unloading. Specific shape changing scenarios, e.g., based on bending, or twisting in prescribed directions, are enabled via the controlled interplay between the active materials and the 3D printed architectures. The physical phenomena are complex and nonintuitive, and so to help understand the interplay of geometric, material, and environmental stimuli parameters we develop 3D nonlinear finite element models. Finally, we create several 2D and 3D shape changing components that demonstrate the role of key parameters and illustrate the broad application potential of the proposed approach. PMID:27109063

3D Printed Reversible Shape Changing Components with Stimuli Responsive Materials

NASA Astrophysics Data System (ADS)

Mao, Yiqi; Ding, Zhen; Yuan, Chao; Ai, Shigang; Isakov, Michael; Wu, Jiangtao; Wang, Tiejun; Dunn, Martin L.; Qi, H. Jerry

2016-04-01

The creation of reversibly-actuating components that alter their shapes in a controllable manner in response to environmental stimuli is a grand challenge in active materials, structures, and robotics. Here we demonstrate a new reversible shape-changing component design concept enabled by 3D printing two stimuli responsive polymers—shape memory polymers and hydrogels—in prescribed 3D architectures. This approach uses the swelling of a hydrogel as the driving force for the shape change, and the temperature-dependent modulus of a shape memory polymer to regulate the time of such shape change. Controlling the temperature and aqueous environment allows switching between two stable configurations - the structures are relatively stiff and can carry load in each - without any mechanical loading and unloading. Specific shape changing scenarios, e.g., based on bending, or twisting in prescribed directions, are enabled via the controlled interplay between the active materials and the 3D printed architectures. The physical phenomena are complex and nonintuitive, and so to help understand the interplay of geometric, material, and environmental stimuli parameters we develop 3D nonlinear finite element models. Finally, we create several 2D and 3D shape changing components that demonstrate the role of key parameters and illustrate the broad application potential of the proposed approach.

Appraisal of comparative single-case experimental designs for instructional interventions with non-reversible target behaviors: Introducing the CSCEDARS ("Cedars").

PubMed

Schlosser, Ralf W; Belfiore, Phillip J; Sigafoos, Jeff; Briesch, Amy M; Wendt, Oliver

2018-05-28

Evidence-based practice as a process requires the appraisal of research as a critical step. In the field of developmental disabilities, single-case experimental designs (SCEDs) figure prominently as a means for evaluating the effectiveness of non-reversible instructional interventions. Comparative SCEDs contrast two or more instructional interventions to document their relative effectiveness and efficiency. As such, these designs have great potential to inform evidence-based decision-making. To harness this potential, however, interventionists and authors of systematic reviews need tools to appraise the evidence generated by these designs. Our literature review revealed that existing tools do not adequately address the specific methodological considerations of comparative SCEDs that aim to compare instructional interventions of non-reversible target behaviors. The purpose of this paper is to introduce the Comparative Single-Case Experimental Design Rating System (CSCEDARS, "cedars") as a tool for appraising the internal validity of comparative SCEDs of two or more non-reversible instructional interventions. Pertinent literature will be reviewed to establish the need for this tool and to underpin the rationales for individual rating items. Initial reliability information will be provided as well. Finally, directions for instrument validation will be proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sensing a buried resonant object by single-channel time reversal.

PubMed

Waters, Zachary J; Dzikowicz, Benjamin R; Holt, R Glynn; Roy, Ronald A

2009-07-01

Scaled laboratory experiments are conducted to assess the efficacy of iterative, single-channel time reversal for enhancement of monostatic returns from resonant spheres in the free field and buried in a sediment phantom. Experiments are performed in a water tank using a broad-band piston transducer operating between 0.4 and 1.5 MHz and calibrated using free surface reflections. Solid and hollow metallic spheres, 6.35 mm in diameter, are buried in a consolidation of 128-microm-mean- diameter spherical glass beads. The procedure consists of exciting the target object with a broadband pulse, sampling the return using a finite time window, reversing the signal in time, and using this reversed signal as the source waveform for the next interrogation. Results indicate that the spectrum of the returns rapidly converges to the dominant mode in the backscattering response of the target. Signal-to-noise enhancement of the target echo is demonstrated for a target at several burial depths. Images generated by scanning the transducer over the location of multiple buried targets demonstrate the ability of the technique to distinguish between targets of differing type and to yield an enhancement of different modes within the response of a single target as a function of transducer position and processing bandwidth.

Picosecond absorption anisotropy of polymethine and squarylium dyes in liquid and polymeric media

NASA Astrophysics Data System (ADS)

Przhonska, Olga V.; Hagan, David J.; Novikov, Evgueni; Lepkowicz, Richard; Van Stryland, Eric W.; Bondar, Mikhail V.; Slominsky, Yuriy L.; Kachkovski, Alexei D.

2001-11-01

Time-resolved excitation-probe polarization measurements are performed for polymethine and squarylium dyes in ethanol and an elastopolymer of polyurethane acrylate (PUA). These molecules exhibit strong excited-state absorption in the visible, which results in reverse saturable absorption (RSA). In pump-probe experiments, we observe a strong angular dependence of the RSA decay kinetics upon variation of the angle between pump and probe polarizations. The difference in absorption anisotropy kinetics in ethanol and PUA is detected and analyzed. Anisotropy decay curves in ethanol follow a single exponential decay leading to complete depolarization of the excited state. We also observe complete depolarization in PUA, in which case the anisotropy decay follows a double exponential behavior. Possible rotations in the PUA polymeric matrix are connected with the existence of local microcavities of free volume. We believe that the fast decay component is connected with the rotation of molecular fragments and the slower decay component is connected with the rotation of entire molecules in local microcavities, which is possible because of the elasticity of the polymeric material.

Reverse Flood Routing with the Lag-and-Route Storage Model

NASA Astrophysics Data System (ADS)

Mazi, K.; Koussis, A. D.

2010-09-01

This work presents a method for reverse routing of flood waves in open channels, which is an inverse problem of the signal identification type. Inflow determination from outflow measurements is useful in hydrologic forensics and in optimal reservoir control, but has been seldom studied. Such problems are ill posed and their solution is sensitive to small perturbations present in the data, or to any related uncertainty. Therefore the major difficulty in solving this inverse problem consists in controlling the amplification of errors that inevitably befall flow measurements, from which the inflow signal is to be determined. The lag-and-route model offers a convenient framework for reverse routing, because not only is formal deconvolution not required, but also reverse routing is through a single linear reservoir. In addition, this inversion degenerates to calculating the intermediate inflow (prior to the lag step) simply as the sum of the outflow and of its time derivative multiplied by the reservoir’s time constant. The remaining time shifting (lag) of the intermediate, reversed flow presents no complications, as pure translation causes no error amplification. Note that reverse routing with the inverted Muskingum scheme (Koussis et al., submitted to the 12th Plinius Conference) fails when that scheme is specialised to the Kalinin-Miljukov model (linear reservoirs in series). The principal functioning of the reverse routing procedure was verified first with perfect field data (outflow hydrograph generated by forward routing of a known inflow hydrograph). The field data were then seeded with random error. To smooth the oscillations caused by the imperfect (measured) outflow data, we applied a multipoint Savitzky-Golay low-pass filter. The combination of reverse routing and filtering achieved an effective recovery of the inflow signal extremely efficiently. Specifically, we compared the reverse routing results of the inverted lag-and-route model and of the inverted Kalinin-Miljukov model. The latter applies the lag-and-route model’s single-reservoir inversion scheme sequentially to its cascade of linear reservoirs, the number of which is related to the stream's hydromorphology. For this purpose, we used the example of Bruen & Dooge (2007), who back-routed flow hydrographs in a 100-km long prismatic channel using a scheme for the reverse solution of the St. Venant equations of flood wave motion. The lag-and-route reverse routing model recovered the inflow hydrograph with comparable accuracy to that of the multi-reservoir, inverted Kalinin-Miljukov model, both performing as well as the box-scheme for reverse routing with the St. Venant equations. In conclusion, the success in the regaining of the inflow signal by the devised single-reservoir reverse routing procedure, with multipoint low-pass filtering, can be attributed to its simple computational structure that endows it with remarkable robustness and exceptional efficiency.

Dual-RiverSonde measurements of two-dimensional river flow patterns

USGS Publications Warehouse

Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Stumpner, P.; Burau, J.R.

2008-01-01

Two-dimensional river flow patterns have been measured using a pair of RiverSondes in two experiments in the Sacramento-San Joaquin River Delta system of central California during April and October 2007. An experiment was conducted at Walnut Grove, California in order to explore the use of dual RiverSondes to measure flow patterns at a location which is important in the study of juvenile fish migration. The data available during the first experiment were limited by low wind, so a second experiment was conducted at Threemile Slough where wind conditions and surface turbulence historically have resulted in abundant data. Both experiments included ADCP near-surface velocity measurements from either manned or unmanned boats. Both experiments showed good comparisons between the RiverSonde and ADCP measurements. The flow conditions at both locations are dominated by tidal effects, with partial flow reversal at Walnut Grove and complete flow reversal at Threemile Slough. Both systems showed complex flow patterns during the flow reversals. Quantitative comparisons between the RiverSondes and an ADCP on a manned boat at Walnut Grove showed mean differences of 4.5 cm/s in the u (eastward) and 7.6 cm/s in the v (northward) components, and RMS differences of 14.7 cm/s in the u component and 21.0 cm/s in the v component. Quantitative comparisons between the RiverSondes and ADCPs on autonomous survey vessels at Threemile Slough showed mean differences of 0.007 cm/s in the u component and 0.5 cm/s in the v component, and RMS differences of 7.9 cm/s in the u component and 13.5 cm/s in the v component after obvious outliers were removed. ?? 2008 IEEE.

Ultraviolet/blue light-emitting diodes based on single horizontal ZnO microrod/GaN heterojunction

PubMed Central

2014-01-01

We report electroluminescence (EL) from single horizontal ZnO microrod (MR) and p-GaN heterojunction light-emitting diodes under forward and reverse bias. EL spectra were composed of two blue emissions centered at 431 and 490 nm under forward biases, but were dominated by a ultraviolet (UV) emission located at 380 nm from n-ZnO MR under high reverse biases. Light-output-current characteristic of the UV emission reveals that the rate of radiative recombination is faster than that of the nonradiative recombination. Highly efficient ZnO excitonic recombination at reverse bias is caused by electrons tunneling from deep-level states near the n-ZnO/p-GaN interface to the conduction band in n-ZnO. PMID:25232299

SpRoUTS (Space Robot Universal Truss System): Reversible Robotic Assembly of Deployable Truss Structures of Reconfigurable Length

NASA Technical Reports Server (NTRS)

Jenett, Benjamin; Cellucci, Daniel; Cheung, Kenneth

2015-01-01

Automatic deployment of structures has been a focus of much academic and industrial work on infrastructure applications and robotics in general. This paper presents a robotic truss assembler designed for space applications - the Space Robot Universal Truss System (SpRoUTS) - that reversibly assembles a truss from a feedstock of hinged andflat-packed components, by folding the sides of each component up and locking onto the assembled structure. We describe the design and implementation of the robot and show that the assembled truss compares favorably with prior truss deployment systems.

21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Single/multiple component metallic bone fixation....3030 Single/multiple component metallic bone fixation appliances and accessories. (a) Identification. Single/multiple component metallic bone fixation appliances and accessories are devices intended to be...

21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Single/multiple component metallic bone fixation....3030 Single/multiple component metallic bone fixation appliances and accessories. (a) Identification. Single/multiple component metallic bone fixation appliances and accessories are devices intended to be...

21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Single/multiple component metallic bone fixation....3030 Single/multiple component metallic bone fixation appliances and accessories. (a) Identification. Single/multiple component metallic bone fixation appliances and accessories are devices intended to be...

21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Single/multiple component metallic bone fixation....3030 Single/multiple component metallic bone fixation appliances and accessories. (a) Identification. Single/multiple component metallic bone fixation appliances and accessories are devices intended to be...

21 CFR 888.3030 - Single/multiple component metallic bone fixation appliances and accessories.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Single/multiple component metallic bone fixation....3030 Single/multiple component metallic bone fixation appliances and accessories. (a) Identification. Single/multiple component metallic bone fixation appliances and accessories are devices intended to be...

Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model

NASA Technical Reports Server (NTRS)

Mercer, C. E.; Maiden, D. L.

1972-01-01

The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude.

A substitution in the transmembrane region of the glycoprotein leads to an unstable attenuation of Machupo virus.

PubMed

Patterson, Michael; Koma, Takaaki; Seregin, Alexey; Huang, Cheng; Miller, Milagros; Smith, Jennifer; Yun, Nadezhda; Smith, Jeanon; Paessler, Slobodan

2014-09-01

Machupo virus (MACV) is the etiologic agent of Bolivian hemorrhagic fever (BHF). Utilizing a reverse-genetics system recently developed, we report the rescue of a rationally modified recombinant MACV containing a single mutation in the transmembrane region of the glycoprotein. Following challenge of susceptible mice, we identified a significant reduction in virulence in the novel virus. We also identified an instability leading to reversion of the single mutation to a wild-type genotype. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Neural network classifications and correlation analysis of EEG and MEG activity accompanying spontaneous reversals of the Necker cube.

PubMed

Gaetz, M; Weinberg, H; Rzempoluck, E; Jantzen, K J

1998-04-01

It has recently been suggested that reentrant connections are essential in systems that process complex information [A. Damasio, H. Damasio, Cortical systems for the retrieval of concrete knowledge: the convergence zone framework, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 61-74; G. Edelman, The Remembered Present, Basic Books, New York, 1989; M.I. Posner, M. Rothbart, Constructing neuronal theories of mind, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 183-199; C. von der Malsburg, W. Schneider, A neuronal cocktail party processor, Biol. Cybem., 54 (1986) 29-40]. Reentry is not feedback, but parallel signalling in the time domain between spatially distributed maps, similar to a process of correlation between distributed systems. Accordingly, it was expected that during spontaneous reversals of the Necker cube, complex patterns of correlations between distributed systems would be present in the cortex. The present study included EEG (n=4) and MEG recordings (n=5). Two experimental questions were posed: (1) Can distributed cortical patterns present during perceptual reversals be classified differently using a generalised regression neural network (GRNN) compared to processing of a two-dimensional figure? (2) Does correlated cortical activity increase significantly during perception of a Necker cube reversal? One-second duration single trials of EEG and MEG data were analysed using the GRNN. Electrode/sensor pairings based on cortico-cortical connections were selected to assess correlated activity in each condition. The GRNN significantly classified single trials recorded during Necker cube reversals as different from single trials recorded during perception of a two-dimensional figure for both EEG and MEG. In addition, correlated cortical activity increased significantly in the Necker cube reversal condition for EEG and MEG compared to the perception of a non-reversing stimulus. Coherent MEG activity observed over occipital, parietal and temporal regions is believed to represent neural systems related to the perception of Necker cube reversals. Copyright 1998 Elsevier Science B.V.

Parallel transmit beamforming using orthogonal frequency division multiplexing applied to harmonic imaging--a feasibility study.

PubMed

Demi, Libertario; Verweij, Martin D; Van Dongen, Koen W A

2012-11-01

Real-time 2-D or 3-D ultrasound imaging systems are currently used for medical diagnosis. To achieve the required data acquisition rate, these systems rely on parallel beamforming, i.e., a single wide-angled beam is used for transmission and several narrow parallel beams are used for reception. When applied to harmonic imaging, the demand for high-amplitude pressure wave fields, necessary to generate the harmonic components, conflicts with the use of a wide-angled beam in transmission because this results in a large spatial decay of the acoustic pressure. To enhance the amplitude of the harmonics, it is preferable to do the reverse: transmit several narrow parallel beams and use a wide-angled beam in reception. Here, this concept is investigated to determine whether it can be used for harmonic imaging. The method proposed in this paper relies on orthogonal frequency division multiplexing (OFDM), which is used to create distinctive parallel beams in transmission. To test the proposed method, a numerical study has been performed, in which the transmit, receive, and combined beam profiles generated by a linear array have been simulated for the second-harmonic component. Compared with standard parallel beamforming, application of the proposed technique results in a gain of 12 dB for the main beam and in a reduction of the side lobes. Experimental verification in water has also been performed. Measurements obtained with a single-element emitting transducer and a hydrophone receiver confirm the possibility of exciting a practical ultrasound transducer with multiple Gaussian modulated pulses, each having a different center frequency, and the capability to generate distinguishable second-harmonic components.

Effect of A-TIG Welding Process on the Weld Attributes of Type 304LN and 316LN Stainless Steels

NASA Astrophysics Data System (ADS)

Vasudevan, M.

2017-03-01

The specific activated flux has been developed for enhancing the penetration performance of TIG welding process for autogenous welding of type 304LN and 316LN stainless steels through systematic study. Initially single-component fluxes were used to study their effect on depth of penetration and tensile properties. Then multi-component activated flux was developed which was found to produce a significant increase in penetration of 10-12 mm in single-pass TIG welding of type 304LN and 316LN stainless steels. The significant improvement in penetration achieved using the activated flux developed in the present work has been attributed to the constriction of the arc and as well as reversal of Marangoni flow in the molten weld pool. The use of activated flux has been found to overcome the variable weld penetration observed in 316LN stainless steel with <50 ppm of sulfur. There was no degradation in the microstructure and mechanical properties of the A-TIG welds compared to that of the welds produced by conventional TIG welding on the contrary the transverse strength properties of the 304LN and 316LN stainless steel welds produced by A-TIG welding exceeded the minimum specified strength values of the base metals. Improvement in toughness values were observed in 316LN stainless steel produced by A-TIG welding due to refinement in the weld microstructure in the region close to the weld center. Thus, activated flux developed in the present work has greater potential for use during the TIG welding of structural components made of type 304LN and 316LN stainless steels.

Interaction of HIV-1 Gag protein components with single DNA molecules

NASA Astrophysics Data System (ADS)

Cruceanu, Margareta; Gorelick, Robert J.; Williams, Mark C.

2003-03-01

The Gag protein of the HIV-1 retrovirus is cleaved into three major proteins as part of viral maturation: nucleocapsid (NC), capsid, and matrix. NC is the first of these proteins to be cleaved, and it is cleaved in three stages into NCp15, followed by NCp9, and finally NCp7. In this study, we use optical tweezers to investigate the capability of these NC proteins to alter the helix-coil transition of single DNA molecules. We have previously shown that the capability to alter the DNA helix-coil transition is an excellent probe of the nucleic acid chaperone activity of NC proteins, in which the secondary structure of nucleic acids is rearranged to facilitate reverse transcription. By examining the capability of NCp15, NCp9, and NCp7 to alter DNA stretching, the current studies will test the role of proteolytic cleavage of Gag in regulating the nucleic acid chaperone activity of NC. Whereas binding studies suggest that NCp9 and NCp15 bind more strongly to DNA than NCp7, our DNA stretching results indicate that these proteins all have similar effects on DNA stretching.

Electrical isolation of component cells in monolithically interconnected modules

DOEpatents

Wanlass, Mark W.

2001-01-01

A monolithically interconnected photovoltaic module having cells which are electrically connected which comprises a substrate, a plurality of cells formed over the substrate, each cell including a primary absorber layer having a light receiving surface and a p-region, formed with a p-type dopant, and an n-region formed with an n-type dopant adjacent the p-region to form a single pn-junction, and a cell isolation diode layer having a p-region, formed with a p-type dopant, and an n-region formed with an n-type dopant adjacent the p-region to form a single pn-junction, the diode layer intervening the substrate and the absorber layer wherein the absorber and diode interfacial regions of a same conductivity type orientation, the diode layer having a reverse-breakdown voltage sufficient to prevent inter-cell shunting, and each cell electrically isolated from adjacent cells with a vertical trench trough the pn-junction of the diode layer, interconnects disposed in the trenches contacting the absorber regions of adjacent cells which are doped an opposite conductivity type, and electrical contacts.

Functional Analysis Identified Habit Reversal Components for the Treatment of Motor Tics

ERIC Educational Resources Information Center

Dufrene, Brad A.; Harpole, Lauren Lestremau; Sterling, Heather E.; Perry, Erin J.; Burton, Britney; Zoder-Martell, Kimberly

2013-01-01

This study included brief functional analyses and treatment for motor tics exhibited by two children with Tourette Syndrome. Brief functional analyses were conducted in an outpatient treatment center and results were used to develop individualized habit reversal procedures. Treatment data were collected in clinic for one child and in clinic and…

Acceptance and Commitment Therapy and Habit Reversal Training for the Treatment of Trichotillomania

ERIC Educational Resources Information Center

Crosby, Jesse M.; Dehlin, John P.; Mitchell, P. R.; Twohig, Michael P.

2012-01-01

Trichotillomania is a behavioral problem, and is often referred to as a habit disorder, but it is important to consider the cognitive and emotional components of the behavior. Current treatment recommendations include a traditional behavioral approach (Habit Reversal Training; HRT) combined with an approach that addresses the cognitive and…

Single-Reaction Multiplex Reverse Transcription PCR for Detection of Zika, Chikungunya, and Dengue Viruses

PubMed Central

Waggoner, Jesse J.; Gresh, Lionel; Mohamed-Hadley, Alisha; Ballesteros, Gabriela; Davila, Maria Jose Vargas; Tellez, Yolanda; Sahoo, Malaya K.; Balmaseda, Angel; Harris, Eva

2016-01-01

Clinical manifestations of Zika virus, chikungunya virus, and dengue virus infections can be similar. To improve virus detection, streamline molecular workflow, and decrease test costs, we developed and evaluated a multiplex real-time reverse transcription PCR for these viruses. PMID:27184629

Nano-Encrypted Morse Code: A Versatile Approach to Programmable and Reversible Nanoscale Assembly and Disassembly

PubMed Central

Wong, Ngo Yin; Xing, Hang; Tan, Li Huey; Lu, Yi

2013-01-01

While much work has been devoted to nanoscale assembly of functional materials, selective reversible assembly of components in the nanoscale pattern at selective sites has received much less attention. Exerting such a reversible control of the assembly process will make it possible to fine-tune the functional properties of the assembly and to realize more complex designs. Herein, by taking advantage of different binding affinities of biotin and desthiobiotin toward streptavidin, we demonstrate selective and reversible decoration of DNA origami tiles with streptavidin, including revealing an encrypted Morse code “NANO” and reversible exchange of uppercase letter “I” with lowercase “i”. The yields of the conjugations are high (> 90%) and the process is reversible. We expect this versatile conjugation technique to be widely applicable with different nanomaterials and templates. PMID:23373425

Modeling of membrane processes for air revitalization and water recovery

NASA Technical Reports Server (NTRS)

Lange, Kevin E.; Foerg, Sandra L.; Dall-Bauman, Liese A.

1992-01-01

Gas-separation and reverse-osmosis membrane models are being developed in conjunction with membrane testing at NASA JSC. The completed gas-separation membrane model extracts effective component permeabilities from multicomponent test data, and predicts the effects of flow configuration, operating conditions, and membrane dimensions on module performance. Variable feed- and permeate-side pressures are considered. The model has been applied to test data for hollow-fiber membrane modules with simulated cabin-air feeds. Results are presented for a membrane designed for air drying applications. Extracted permeabilities are used to predict the effect of operating conditions on water enrichment in the permeate. A first-order reverse-osmosis model has been applied to test data for spiral wound membrane modules with a simulated hygiene water feed. The model estimates an effective local component rejection coefficient under pseudosteady-state conditions. Results are used to define requirements for a detailed reverse-osmosis model.

Complications in reverse shoulder arthroplasty

PubMed Central

Barco, Raul; Savvidou, Olga D.; Sperling, John W.; Sanchez-Sotelo, Joaquín; Cofield, Robert H.

2016-01-01

The reported rate of complications of reverse shoulder arthroplasty (RSA) seems to be higher than the complication rate of anatomical total shoulder arthroplasty. The reported overall complication rate of primary RSA is approximately 15%; when RSA is used in the revision setting, the complication rate may approach 40%. The most common complications of RSA include instability, infection, notching, loosening, nerve injury, acromial and scapular spine fractures, intra-operative fractures and component disengagement. Careful attention to implant design and surgical technique, including implantation of components in the correct version and height, selection of the best glenosphere-humeral bearing match, avoidance of impingement, and adequate management of the soft tissues will hopefully translate in a decreasing number of complications in the future. Cite this article: Barco R, Savvidou OD, Sperling JW, Sanchez-Sotelo J, Cofield RH. Complications in reverse shoulder arthroplasty. EFORT Open Rev 2016;1:72-80. DOI: 10.1302/2058-5241.1.160003. PMID:28461931

Complications in reverse shoulder arthroplasty.

PubMed

Barco, Raul; Savvidou, Olga D; Sperling, John W; Sanchez-Sotelo, Joaquín; Cofield, Robert H

2016-03-01

The reported rate of complications of reverse shoulder arthroplasty (RSA) seems to be higher than the complication rate of anatomical total shoulder arthroplasty.The reported overall complication rate of primary RSA is approximately 15%; when RSA is used in the revision setting, the complication rate may approach 40%.The most common complications of RSA include instability, infection, notching, loosening, nerve injury, acromial and scapular spine fractures, intra-operative fractures and component disengagement.Careful attention to implant design and surgical technique, including implantation of components in the correct version and height, selection of the best glenosphere-humeral bearing match, avoidance of impingement, and adequate management of the soft tissues will hopefully translate in a decreasing number of complications in the future. Cite this article: Barco R, Savvidou OD, Sperling JW, Sanchez-Sotelo J, Cofield RH. Complications in reverse shoulder arthroplasty. EFORT Open Rev 2016;1:72-80. DOI: 10.1302/2058-5241.1.160003.

Reversing the Underachievement of Gifted Middle School Students: Lessons from Another Field

ERIC Educational Resources Information Center

Ritchotte, Jennifer; Rubenstein, Lisa; Murry, Francie

2015-01-01

Underachievement often begins in middle school for gifted students. Unfortunately, there is no single intervention that will ameliorate underachievement for all gifted students. To date, interventions aimed at reversing the underachieving behaviors of gifted middle school students have been inconsistent and inconclusive. To create an effective…

Efficient sampling of reversible cross-linking polymers: Self-assembly of single-chain polymeric nanoparticles

NASA Astrophysics Data System (ADS)

Oyarzún, Bernardo; Mognetti, Bortolo Matteo

2018-03-01

We present a new simulation technique to study systems of polymers functionalized by reactive sites that bind/unbind forming reversible linkages. Functionalized polymers feature self-assembly and responsive properties that are unmatched by the systems lacking selective interactions. The scales at which the functional properties of these materials emerge are difficult to model, especially in the reversible regime where such properties result from many binding/unbinding events. This difficulty is related to large entropic barriers associated with the formation of intra-molecular loops. In this work, we present a simulation scheme that sidesteps configurational costs by dedicated Monte Carlo moves capable of binding/unbinding reactive sites in a single step. Cross-linking reactions are implemented by trial moves that reconstruct chain sections attempting, at the same time, a dimerization reaction between pairs of reactive sites. The model is parametrized by the reaction equilibrium constant of the reactive species free in solution. This quantity can be obtained by means of experiments or atomistic/quantum simulations. We use the proposed methodology to study the self-assembly of single-chain polymeric nanoparticles, starting from flexible precursors carrying regularly or randomly distributed reactive sites. We focus on understanding differences in the morphology of chain nanoparticles when linkages are reversible as compared to the well-studied case of irreversible reactions. Intriguingly, we find that the size of regularly functionalized chains, in good solvent conditions, is non-monotonous as a function of the degree of functionalization. We clarify how this result follows from excluded volume interactions and is peculiar of reversible linkages and regular functionalizations.

Self-discharge characteristic and mechanism of single-phase PuNi3-, Gd2Co7-, and Pr5Co19-type Nd-Mg-Ni-based alloys

NASA Astrophysics Data System (ADS)

Jia, Zeru; Zhang, Lu; Zhao, Yumeng; Cao, Juan; Li, Yuan; Dong, Zhentao; Wang, Wenfeng; Han, Shumin

2017-12-01

To decrease the self-discharge rate of the nickel metal hydride batteries, the self-discharge characteristic and mechanism of single-phase PuNi3-, Gd2Co7-, and Pr5Co19-type Nd-Mg-Ni-based alloys are studied from the perspective of structure in this work. It is found that the self-discharge rate of the alloy electrodes gradually increases with a rising [NdNi5]/[NdMgNi4] subunit ratio. The factors resulting in reversible and irreversible self-discharge are analyzed by electrochemical pressure-composition isotherms, Tafel and SEM measurements. Electrochemical P-C isotherms show that with the increasing [NdNi5]/[NdMgNi4] subunit ratio, the hydrogen desorption plateau pressure sharply elevates, leading to less stability of the corresponding hydride and more reversible self-discharge of the alloys; whereas, corrosion current density of the three alloy electrodes gradually decreases and SEM shows that the amount of hydroxide accumulating on the alloy surface diminishes, indicating the oxidation/corrosion degree alleviates and less irreversible self-discharge with the higher [NdNi5]/[NdMgNi4] ratio. By calculating the proportion of reversible and irreversible self-discharge in total capacity loss, we find that the reversible self-discharge is nearly more than 90% for the three single-phase alloys, while irreversible self-discharge is less than 10%, which illustrates that reversible self-discharge is the dominate factor in self-discharge of Nd-Mg-Ni-based alloys in this study.

Reversible air-induced optical and electrical modulation of methylammonium lead bromide (MAPbBr3) single crystals

NASA Astrophysics Data System (ADS)

Zhang, Huotian; Liu, Yiting; Lu, Haizhou; Deng, Wan; Yang, Kang; Deng, Zunyi; Zhang, Xingmin; Yuan, Sijian; Wang, Jiao; Niu, Jiaxin; Zhang, Xiaolei; Jin, Qingyuan; Feng, Hongjian; Zhan, Yiqiang; Zheng, Lirong

2017-09-01

The photoluminescence (PL) variations of organic-inorganic hybrid lead halide perovskites in different atmospheres are well documented, while the fundamental mechanism still lacks comprehensive understandings. This study reports the reversible optical and electrical properties of methylammonium lead bromide (MAPbBr3 or CH3NH3PbBr3) single crystals caused by air infiltration. With the change in the surrounding atmosphere from air to vacuum, the PL intensity of perovskite single crystals decreases, while the conductivity increases. By means of first-principles computational studies, the shallow trap states are considered as key elements in PL and conductivity changes. These results have important implications for the characterization and application of organic-inorganic hybrid lead halide perovskites in vacuum.

Reversible Negative Resistive Switching in an Individual Fe@Al2O3 Hybrid Nanotube for Nonvolatile Memory.

PubMed

Ye, Yalong; Zhao, Jie; Xiao, Li; Cheng, Baochang; Xiao, Yanhe; Lei, Shuijin

2018-06-06

Hybrid nanostructures can show enormous potential in different areas because of their unique structural configurations. Herein, Fe@Al 2 O 3 hybrid nanotubes are constructed via a homogeneous coprecipitation method followed by subsequent annealing in a reducing atmosphere. The introduction of zero band gap Fe nanocrystals in the wall of ultrawide band gap Al 2 O 3 insulator nanotubes results in the formation of charge trap centers, and correspondingly a single hybrid nanotube-based two-terminal device can show reversible negative resistive switching (RS) characteristics with symmetrical negative differential resistance (NDR) at relatively high operation bias voltages. At a large bias voltage, holes and electrons can be injected into traps at two ends from electrodes, respectively, and then captured. The bias voltage dependence of asymmetrical filling of charges can lead to a reversible variation of built-in electromotive force, and therefore the symmetrical negative RS with NDR arises from two reversible back-to-back series bipolar RS. At a low readout voltage, the single Fe@Al 2 O 3 hybrid nanotube can show an excellent nonvolatile memory feature with a relatively large switching ratio of ∼30. The bias-governed reversible negative RS with superior stability, reversibility, nondestructive readout, and remarkable cycle performance makes it a potential candidate in next-generation erasable nonvolatile resistive random access memories.

Problem parental care and teenage deliberate self-harm in young community adults.

PubMed

Bifulco, Antonia; Schimmenti, Adriano; Moran, Patricia; Jacobs, Catherine; Bunn, Amanda; Rusu, Adina Carmen

2014-01-01

Deliberate self-harm (DSH) in young people is a clinical and social problem related to early maltreatment but with little specificity in type of care or abuse determined. A community sample of 160 high-risk young people (aged 16-30) were the offspring of mothers' previously interviewed as vulnerable to major depression. The youth were interviewed to determine DSH (both suicidal and nonsuicidal), childhood maltreatment (using the Childhood Experience of Care and Abuse interview) and major depression (using SCID for DSMIV) before age 17. Around one fifth reported DSH; equal proportions were suicidal and nonsuicidal with a fourth of these with both. DSH was highly related to family context (single mother upbringing and family discord) and poor parental care (including antipathy, neglect, inadequate supervision, and role reversal). Highest odds ratios were for role reversal (OR = 17) and neglect (OR = 11). DSH was unrelated to any type of abuse. Logistic regression showed that role reversal, inadequate supervision, and teenage depression all modeled DSH. There was some specificity, with single mother upbringing, role reversal, and inadequate supervision predicting nonsuicidal DSH, and neglect and role reversal alone predicting suicidal DSH. Role reversal remained a key predictor for both types of DSH when controls were applied. Poor childhood care, which has implications for problematic emotion regulation and empoverished social development, needs to be understood to improve interventions and treatment for DSH in young people.

Influence of cochlear traveling wave and neural adaptation on auditory brainstem responses.

PubMed

Junius, Dirk; Dau, Torsten

2005-07-01

The present study investigates the relationship between evoked responses to transient broadband chirps and responses to the same chirps when embedded in longer-duration stimuli. It examines to what extent the responses to the composite stimuli can be explained by a linear superposition of the responses to the single components, as a function of stimulus level. In the first experiment, a single rising chirp was temporally and spectrally embedded in two steady-state tones. In the second experiment, the stimulus consisted of a continuous alternating train of chirps: each rising chirp was followed by the temporally reversed (falling) chirp. In both experiments, the transitions between stimulus components were continuous. For stimulation levels up to approximately 70 dB SPL, the responses to the embedded chirp corresponded to the responses to the single chirp. At high stimulus levels (80-100 dB SPL), disparities occurred between the responses, reflecting a nonlinearity in the processing when neural activity is integrated across frequency. In the third experiment, the effect of within-train rate on wave-V response was investigated. The response to the chirp presented at a within-train rate of 95 Hz exhibited the same amplitude as that to the chirp presented in the traditional single-stimulus paradigm at a rate of 13 Hz. For a corresponding experiment with bandlimited chirps of 4 ms duration, where the within-train rate was 250 Hz, a clear reduction of the response amplitude was observed. This nonlinearity in terms of temporal processing most likely reflects effects of short-term adaptation. Overall, the results of the present study further demonstrate the importance of cochlear processing for the formation of brainstem potentials. The data may provide constraints on future models of peripheral processing in the human auditory system. The findings might also be useful for the development of effective stimulation paradigms in clinical applications.

Reversible dilatancy in entangled single-wire materials.

PubMed

Rodney, David; Gadot, Benjamin; Martinez, Oriol Riu; du Roscoat, Sabine Rolland; Orgéas, Laurent

2016-01-01

Designing structures that dilate rapidly in both tension and compression would benefit devices such as smart filters, actuators or fasteners. This property however requires an unusual Poisson ratio, or Poisson function at finite strains, which has to vary with applied strain and exceed the familiar bounds: less than 0 in tension and above 1/2 in compression. Here, by combining mechanical tests and discrete element simulations, we show that a simple three-dimensional architected material, made of a self-entangled single long coiled wire, behaves in between discrete and continuum media, with a large and reversible dilatancy in both tension and compression. This unusual behaviour arises from an interplay between the elongation of the coiled wire and rearrangements due to steric effects, which, unlike in traditional discrete media, are hysteretically reversible when the architecture is made of an elastic fibre.

Sensing Reversible Protein–Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors

PubMed Central

2015-01-01

We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor’s response at various ionic strengths was analyzed. Furthermore, protein “fingerprints” of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS). PMID:25126155

Acetylcholine-hydrolyzing activities in soluble brain fraction: Characterization with reversible and irreversible inhibitors.

PubMed

Estévez, Jorge; Selva, Verónica; Benabent, Mónica; Mangas, Iris; Sogorb, Miguel Ángel; Vilanova, Eugenio

2016-11-25

Some effects of organophosphorus compounds (OPs) esters cannot be explained through actions on currently recognized targets acetylcholinesterase or neuropathy target esterase (NTE). In soluble chicken brain fraction, three components (Eα, Eβ and Eγ) of pheny lvalerate esterase activity (PVase) were kinetically discriminated and their relationship with acetylcholine-hydrolyzing activity (cholinesterase activity) were studied in previous works. In this work, four enzymatic components (CS1, CS2, CS3 and CS4) of cholinesterase activity have been discriminated in soluble fraction, according to their sensitivity to irreversible inhibitors mipafox, paraoxon, PMSF and iso-OMPA and to reversible inhibitors ethopropazine and BW284C51. Cholinesterase component CS1 can be related to the Eα component of PVase activity and identified as butyrylcholinesterase (BuChE). No association and similarities can be stablished among the other PVase component (Eβ and Eγ) with the other cholinesterase components (CS2, CS3, CS4). The kinetic analysis has allowed us to stablish a method for discriminating the enzymatic component based on a simple test with two inhibitors. It can be used as biomarker in toxicological studies and for monitoring these cholinesterase components during isolation and molecular identification processes, which will allow OP toxicity to be understood by a multi-target approach. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Strain doping: Reversible single-axis control of a complex oxide lattice via helium implantation

DOE PAGES

Guo, Hangwen; Dong, Shuai; Rack, Philip D.; ...

2015-06-25

We report on the use of helium ion implantation to independently control the out-of-plane lattice constant in epitaxial La 0.7Sr 0.3MnO 3 thin films without changing the in-plane lattice constants. The process is reversible by a vacuum anneal. Resistance and magnetization measurements show that even a small increase in the out-of-plane lattice constant of less than 1% can shift the metal-insulator transition and Curie temperatures by more than 100 °C. Unlike conventional epitaxy-based strain tuning methods which are constrained not only by the Poisson effect but by the limited set of available substrates, the present study shows that strain canmore » be independently and continuously controlled along a single axis. This permits novel control over orbital populations through Jahn-Teller effects, as shown by Monte Carlo simulations on a double-exchange model. As a result, the ability to reversibly control a single lattice parameter substantially broadens the phase space for experimental exploration of predictive models and leads to new possibilities for control over materials’ functional properties.« less

European Non-Dissipative Bypass Switch For Li-Ion Batteries And Prospective

NASA Astrophysics Data System (ADS)

Pasquier, E.; Castric, AF.; Mosset, E.; Chandeneau, A.

2011-10-01

Li-ion batteries are made of cells or modules connected in series. In case one may be too weak or failed, it becomes necessary to remove it from the serial circuit. This is the by-pass operation which provides overcharge/open-circuitprotection,limitation of possible constraints linked to over- discharge/reversal/"self-short" and avoid to jeopardize rest of battery. One system is particularly adapted to Space Li-ion batteries: the "make before break" Single Pole Double Throw (SPDT) switch which avoids open- circuit on power circuit when correctly activated. This paper presents the component constraints, the development in the frame of ESA Artès 3 program up to its qualification, as well as the motorization approach linked to ECSS-E-30 (mechanical - Part 3: Mechanisms) and future opportunities of such system.

The Croton megalobotrys Müll Arg. traditional medicine in HIV/AIDS management: Documentation of patient use, in vitro activation of latent HIV-1 provirus, and isolation of active phorbol esters.

PubMed

Tietjen, Ian; Ngwenya, Barbara N; Fotso, Ghislain; Williams, David E; Simonambango, Sundana; Ngadjui, Bonaventure T; Andersen, Raymond J; Brockman, Mark A; Brumme, Zabrina L; Andrae-Marobela, Kerstin

2018-01-30

Current HIV therapies do not act on latent cellular HIV reservoirs; hence they are not curative. While experimental latency reversal agents (LRAs) can promote HIV expression in these cells, thereby exposing them to immune recognition, existing LRAs exhibit limited clinical efficacy and high toxicity. We previously described a traditional 3-step medicinal plant regimen used for HIV/AIDS management in Northern Botswana that inhibits HIV replication in vitro. Here we describe use of one component of the regimen that additionally contains novel phorbol esters possessing HIV latency-reversal properties. We sought to document experiences of traditional medicine users, assess the ability of traditional medicine components to reverse HIV latency in vitro, and identify pure compounds that conferred these activities. Experiences of two HIV-positive traditional medicine users (patients) were documented using qualitative interview techniques. Latency reversal activity was assessed using a cell-based model (J-Lat, clone 9.2). Crude plant extracts were fractionated by open column chromatography and reverse-phase HPLC. Compound structures were elucidated using NMR spectroscopy and mass spectrometry. Patients using the 3-step regimen reported improved health over several years despite no reported use of standard HIV therapies. Crude extracts from Croton megalobotrys Müll Arg. ("Mukungulu"), the third component of the 3-step regimen, induced HIV expression in J-lat cells to levels comparable to the known LRA prostratin. Co-incubation with known LRAs and pharmacological inhibitors indicated that the active agent(s) in C. megalobotrys were likely to be protein kinase C (PKC) activator(s). Consistent with these results, two novel phorbol esters (Namushen 1 and 2) were isolated as abundant components of C. megalobotrys and were sufficient to confer HIV latency reversal in vitro. We have identified novel LRAs of the phorbol ester class from a medicinal plant used in HIV/AIDS management. These data, combined with self-reported health effects and previously-described in vitro anti-HIV activities of this traditional 3-step regimen, support the utility of longitudinal observational studies of patients undergoing this regimen to quantify its effects on plasma viral loads and HIV reservoir size in vivo. Copyright © 2017 Elsevier B.V. All rights reserved.

High power density dc/dc converter: Selection of converter topology

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.

1990-01-01

The work involved in the identification and selection of a suitable converter topology is described. Three new dc/dc converter topologies are proposed: Phase-Shifted Single Active Bridge DC/DC Converter; Single Phase Dual Active Bridges DC/DC Converter; and Three Phase Dual Active Bridges DC/DC Converter (Topology C). The salient features of these topologies are: (1) All are minimal in structure, i.e., each consists of an input and output bridge, input and output filter and a transformer, all components essential for a high power dc/dc conversion process; (2) All devices of both the bridges can operate under near zero-voltage conditions, making possible a reduction of device switching losses and hence, an increase in switching frequency; (3) All circuits operate at a constant frequency, thus simplifying the task of the magnetic and filter elements; (4) Since, the leakage inductance of the transformer is used as the main current transfer element, problems associated with the diode reverse recovery are eliminated. Also, this mode of operation allows easy paralleling of multiple modules for extending the power capacity of the system; (5) All circuits are least sensitive to parasitic impedances, infact the parasitics are efficently utilized; and (6) The soft switching transitions, result in low electromagnetic interference. A detailed analysis of each topology was carried out. Based on the analysis, the various device and component ratings for each topology operating at an optimum point, and under the given specifications, are tabulated and discussed.

Nuclear physics of reverse electron flow at pulsar polar caps

NASA Astrophysics Data System (ADS)

Jones, P. B.

2010-01-01

Protons produced in electromagnetic showers formed by the reverse electron flux are usually the largest component of the time-averaged polar cap open magnetic flux line current in neutron stars with positive corotational charge density. Although the electric field boundary conditions in the corotating frame are time independent, instabilities on both medium and short time-scales cause the current to alternate between states in which either protons or positrons and ions form the major component. These properties are briefly discussed in relation to nulling and microstructure in radio pulsars, pair production in an outer gap and neutron stars with high surface temperatures.

Search for Time Reversal Violating Effects: R-Correlation Measurement in Neutron Decay.

PubMed

Bodek, K; Ban, G; Beck, M; Bialek, A; Bryś, T; Czarnecki, A; Fetscher, W; Gorel, P; Kirch, K; Kistryn, St; Kozela, A; Kuźniak, M; Lindroth, A; Naviliat-Cuncic, O; Pulut, J; Serebrov, A; Severijns, N; Stephan, E; Zejma, J

2005-01-01

An experiment aiming at the simultaneous determination of both transversal polarization components of electrons emitted in the decay of free neutrons begins data taking using the polarized cold neutron beam (FUNSPIN) from the Swiss Neutron Spallation Source (SINQ) at the Paul-Scherrer Institute, Villigen. A non-zero value of R due to the e(-) polarization component, which is perpendicular to the plane spanned by the spin of the decaying neutron and the electron momentum, would signal a violation of time reversal symmetry and thus physics beyond the Standard Model. Present status of the project and the results from analysis of the first data sample will be discussed.

Bottom-up derivation of conservative and dissipative interactions for coarse-grained molecular liquids with the conditional reversible work method

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

Deichmann, Gregor; Marcon, Valentina; Vegt, Nico F. A. van der, E-mail: vandervegt@csi.tu-darmstadt.de

Molecular simulations of soft matter systems have been performed in recent years using a variety of systematically coarse-grained models. With these models, structural or thermodynamic properties can be quite accurately represented while the prediction of dynamic properties remains difficult, especially for multi-component systems. In this work, we use constraint molecular dynamics simulations for calculating dissipative pair forces which are used together with conditional reversible work (CRW) conservative forces in dissipative particle dynamics (DPD) simulations. The combined CRW-DPD approach aims to extend the representability of CRW models to dynamic properties and uses a bottom-up approach. Dissipative pair forces are derived frommore » fluctuations of the direct atomistic forces between mapped groups. The conservative CRW potential is obtained from a similar series of constraint dynamics simulations and represents the reversible work performed to couple the direct atomistic interactions between the mapped atom groups. Neopentane, tetrachloromethane, cyclohexane, and n-hexane have been considered as model systems. These molecular liquids are simulated with atomistic molecular dynamics, coarse-grained molecular dynamics, and DPD. We find that the CRW-DPD models reproduce the liquid structure and diffusive dynamics of the liquid systems in reasonable agreement with the atomistic models when using single-site mapping schemes with beads containing five or six heavy atoms. For a two-site representation of n-hexane (3 carbons per bead), time scale separation can no longer be assumed and the DPD approach consequently fails to reproduce the atomistic dynamics.« less

Cadaveric and three-dimensional computed tomography study of the morphology of the scapula with reference to reversed shoulder prosthesis

PubMed Central

Torrens, Carlos; Corrales, Monica; Gonzalez, Gemma; Solano, Alberto; Cáceres, Enrique

2008-01-01

Purpose The purpose of this study is to analyze the morphology of the scapula with reference to the glenoid component implantation in reversed shoulder prosthesis, in order to improve primary fixation of the component. Methods Seventy-three 3-dimensional computed tomography of the scapula and 108 scapular dry specimens were analyzed to determine the anterior and posterior length of the glenoid neck, the angle between the glenoid surface and the upper posterior column of the scapula and the angle between the major craneo-caudal glenoid axis and the base of the coracoid process and the upper posterior column. Results The anterior and posterior length of glenoid neck was classified into two groups named "short-neck" and "long-neck" with significant differences between them. The angle between the glenoid surface and the upper posterior column of the scapula was also classified into two different types: type I (mean 50°–52°) and type II (mean 62,50°–64°), with significant differences between them (p < 0,001). The angle between the major craneo-caudal glenoid axis and the base of the coracoid process averaged 18,25° while the angle with the upper posterior column of the scapula averaged 8°. Conclusion Scapular morphological variability advices for individual adjustments of glenoid component implantation in reversed total shoulder prosthesis. Three-dimensional computed tomography of the scapula constitutes an important tool when planning reversed prostheses implantation. PMID:18847487

Cadaveric and three-dimensional computed tomography study of the morphology of the scapula with reference to reversed shoulder prosthesis.

PubMed

Torrens, Carlos; Corrales, Monica; Gonzalez, Gemma; Solano, Alberto; Cáceres, Enrique

2008-10-10

The purpose of this study is to analyze the morphology of the scapula with reference to the glenoid component implantation in reversed shoulder prosthesis, in order to improve primary fixation of the component. Seventy-three 3-dimensional computed tomography of the scapula and 108 scapular dry specimens were analyzed to determine the anterior and posterior length of the glenoid neck, the angle between the glenoid surface and the upper posterior column of the scapula and the angle between the major craneo-caudal glenoid axis and the base of the coracoid process and the upper posterior column. The anterior and posterior length of glenoid neck was classified into two groups named "short-neck" and "long-neck" with significant differences between them. The angle between the glenoid surface and the upper posterior column of the scapula was also classified into two different types: type I (mean 50 degrees-52 degrees ) and type II (mean 62.50 degrees-64 degrees ), with significant differences between them (p < 0.001). The angle between the major craneo-caudal glenoid axis and the base of the coracoid process averaged 18,25 degrees while the angle with the upper posterior column of the scapula averaged 8 degrees . Scapular morphological variability advices for individual adjustments of glenoid component implantation in reversed total shoulder prosthesis. Three-dimensional computed tomography of the scapula constitutes an important tool when planning reversed prostheses implantation.

A paleomagnetic and paleointensity study on Pleistocene and Pliocene basaltic flows from the Djavakheti Highland (Southern Georgia, Caucasus)

NASA Astrophysics Data System (ADS)

Calvo-Rathert, Manuel; Goguitchaichvili, Avto; Bógalo, María-Felicidad; Vegas-Tubía, Néstor; Carrancho, Ángel; Sologashvili, Jemal

2011-08-01

New paleomagnetic, rock-magnetic and paleointensity results obtained on samples from 23 basaltic lava flows belonging to four different flow sequences (Mashavera, Kvemo Orozmani, Zemo Karabulaki and Diliska) of Pleistocene and Pliocene age from the eastern Djavakheti Highland, in southern Georgia, are presented. Radiometric dating of these sequences yields ages between 1.8 and 2.18 Ma for Mashavera, 2.07 and 2.58 Ma for Zemo-Karabulakhi and 2.12 and 3.27 for Diliska. No radiometric ages are available for the Kvemo Orozmani sequence, which is considered to be coeval to the Mashavera sequence. Rock-magnetic experiments including measurement of thermomagnetic, hysteresis and IRM-acquisition curves suggest low-Ti titanomagnetite as main carrier of remanence, although a lower Curie-temperature component was also observed in several cases. Reversible and non-reversible curves were recorded in thermomagnetic experiments. Paleomagnetic analysis generally indicated the presence of a single component (mainly in the Mashavera sequence), but also two more or less superimposed components in some other cases. In 21 sites a characteristic component could be determined and all except one were characterised by normal-polarity directions. Flows from the Mashavera sequence had a rather steep inclination (73.1°). Nevertheless, a mean paleomagnetic direction of all four sequences is obtained ( D = 8.5°, I = 60.8°, N = 4, α95 = 11.7°, k = 62.7) which agrees with the Plio-Quaternary directions obtained in previous studies in Georgia. The paleomagnetic pole obtained (latitude ϕ = 82.1°, longitude λ = 118.2°, A95 = 8.0°, k = 240.7) agrees with the pole values of both the 0 Ma and the 5 Ma windows of the synthetic Eurasian polar wander path from Besse and Courtillot (2002). In order to analyse the behaviour of secular variation, the scatter of paleosecular variation of virtual geomagnetic poles of both the Mashavera flow and all 18 studied flows of Pleistocene age was calculated. It could be observed that both data-sets seem to fit well the expected scatter at latitude 41°N. Paleointensity experiments were carried out with the Coe modification of the Thellier method. Twenty-five out of 84 samples (30%) provided reliable paleointensity results. These successful results were mainly obtained in the Mashavera sequence. Most flows yielded paleointensity results in the 30-45 μT range, in accordance with expected Pliocene to present day intensities. Two flows, however, located near the top of the Mashavera sequence yield high paleointensity values around 60 μT. Anomalous paleointensity results in the upper-lying Mashavera flows together with the steep inclinations observed in that sequence, could perhaps signal the near onset of the Olduvai-Matuyama reversal.

Reverse engineering of wörner type drilling machine structure.

NASA Astrophysics Data System (ADS)

Wibowo, A.; Belly, I.; llhamsyah, R.; Indrawanto; Yuwana, Y.

2018-03-01

A product design needs to be modified based on the conditions of production facilities and existing resource capabilities without reducing the functional aspects of the product itself. This paper describes the reverse engineering process of the main structure of the wörner type drilling machine to obtain a machine structure design that can be made by resources with limited ability by using simple processes. Some structural, functional and the work mechanism analyzes have been performed to understand the function and role of each basic components. The process of dismantling of the drilling machine and measuring each of the basic components was performed to obtain sets of the geometry and size data of each component. The geometric model of each structure components and the machine assembly were built to facilitate the simulation process and machine performance analysis that refers to ISO standard of drilling machine. The tolerance stackup analysis also performed to determine the type and value of geometrical and dimensional tolerances, which could affect the ease of the components to be manufactured and assembled

Deciphering the ubiquitin-mediated pathway in apicomplexan parasites: a potential strategy to interfere with parasite virulence.

PubMed

Ponts, Nadia; Yang, Jianfeng; Chung, Duk-Won Doug; Prudhomme, Jacques; Girke, Thomas; Horrocks, Paul; Le Roch, Karine G

2008-06-11

Reversible modification of proteins through the attachment of ubiquitin or ubiquitin-like modifiers is an essential post-translational regulatory mechanism in eukaryotes. The conjugation of ubiquitin or ubiquitin-like proteins has been demonstrated to play roles in growth, adaptation and homeostasis in all eukaryotes, with perturbation of ubiquitin-mediated systems associated with the pathogenesis of many human diseases, including cancer and neurodegenerative disorders. Here we describe the use of an HMM search of functional Pfam domains found in the key components of the ubiquitin-mediated pathway necessary to activate and reversibly modify target proteins in eight apicomplexan parasitic protozoa for which complete or late-stage genome projects exist. In parallel, the same search was conducted on five model organisms, single-celled and metazoans, to generate data to validate both the search parameters employed and aid paralog classification in Apicomplexa. For each of the 13 species investigated, a set of proteins predicted to be involved in the ubiquitylation pathway has been identified and demonstrates increasing component members of the ubiquitylation pathway correlating with organism and genome complexity. Sequence homology and domain architecture analyses facilitated prediction of apicomplexan-specific protein function, particularly those involved in regulating cell division during these parasite's complex life cycles. This study provides a comprehensive analysis of proteins predicted to be involved in the apicomplexan ubiquitin-mediated pathway. Given the importance of such pathway in a wide variety of cellular processes, our data is a key step in elucidating the biological networks that, in part, direct the pathogenicity of these parasites resulting in a massive impact on global health. Moreover, apicomplexan-specific adaptations of the ubiquitylation pathway may represent new therapeutic targets for much needed drugs against apicomplexan parasites.

Spatial learning and psychomotor performance of C57BL/6 mice: age sensitivity and reliability of individual differences.

PubMed

de Fiebre, Nancyellen C; Sumien, Nathalie; Forster, Michael J; de Fiebre, Christopher M

2006-09-01

Two tests often used in aging research, the elevated path test and the Morris water maze test, were examined for their application to the study of brain aging in a large sample of C57BL/6JNia mice. Specifically, these studies assessed: (1) sensitivity to age and the degree of interrelatedness among different behavioral measures derived from these tests, (2) the effect of age on variation in the measurements, and (3) the reliability of individual differences in performance on the tests. Both tests detected age-related deficits in group performance that occurred independently of each other. However, analysis of data obtained on the Morris water maze test revealed three relatively independent components of cognitive performance. Performance in initial acquisition of spatial learning in the Morris maze was not highly correlated with performance during reversal learning (when mice were required to learn a new spatial location), whereas performance in both of those phases was independent of spatial performance assessed during a single probe trial administered at the end of acquisition training. Moreover, impaired performance during initial acquisition could be detected at an earlier age than impairments in reversal learning. There were modest but significant age-related increases in the variance of both elevated path test scores and in several measures of learning in the Morris maze test. Analysis of test scores of mice across repeated testing sessions confirmed reliability of the measurements obtained for cognitive and psychomotor function. Power calculations confirmed that there are sufficiently large age-related differences in elevated path test performance, relative to within age variability, to render this test useful for studies into the ability of an intervention to prevent or reverse age-related deficits in psychomotor performance. Power calculations indicated a need for larger sample sizes for detection of intervention effects on cognitive components of the Morris water maze test, at least when implemented at the ages tested in this study. Variability among old mice in both tests, including each of the various independent measures in the Morris maze, may be useful for elucidating the biological bases of different aspects of dysfunctional brain aging.

Designing Novel Quaternary Quantum Reversible Subtractor Circuits

NASA Astrophysics Data System (ADS)

Haghparast, Majid; Monfared, Asma Taheri

2018-01-01

Reversible logic synthesis is an important area of current research because of its ability to reduce energy dissipation. In recent years, multiple valued logic has received great attention due to its ability to reduce the width of the reversible circuit which is a main requirement in quantum technology. Subtractor circuits are between major components used in quantum computers. In this paper, we will discuss the design of a quaternary quantum reversible half subtractor circuit using quaternary 1-qudit, 2-qudit Muthukrishnan-Stroud and 3-qudit controlled gates and a 2-qudit Generalized quaternary gate. Then a design of a quaternary quantum reversible full subtractor circuit based on the quaternary half subtractor will be presenting. The designs shall then be evaluated in terms of quantum cost, constant input, garbage output, and hardware complexity. The proposed quaternary quantum reversible circuits are the first attempt in the designing of the aforementioned subtractor.

Digit reversal in children's writing: a simple theory and its empirical validation.

PubMed

Fischer, Jean-Paul

2013-06-01

This article presents a simple theory according to which the left-right reversal of single digits by 5- and 6-year-old children is mainly due to the application of an implicit right-writing or -orienting rule. A number of nontrivial predictions can be drawn from this theory. First, left-oriented digits (1, 2, 3, 7, and 9) will be reversed more frequently than the other asymmetrical digits (4, 5, and 6). Second, for some pairs of digits, the correct writing of the preceding digit will statistically predict the reversal of the current digit and vice versa. Third, writing hand will have little effect on the frequency of reversals, and the relative frequencies with which children reverse the asymmetrical digits will be similar regardless of children's preferred writing hand. Fourth, children who reverse the left-oriented digits the most are also those who reverse the other asymmetrical digits the least. An empirical study involving 367 5- and 6-year-olds confirmed these predictions. Copyright © 2013 Elsevier Inc. All rights reserved.

Zero field reversal probability in thermally assisted magnetization reversal

NASA Astrophysics Data System (ADS)

Prasetya, E. B.; Utari; Purnama, B.

2017-11-01

This paper discussed about zero field reversal probability in thermally assisted magnetization reversal (TAMR). Appearance of reversal probability in zero field investigated through micromagnetic simulation by solving stochastic Landau-Lifshitz-Gibert (LLG). The perpendicularly anisotropy magnetic dot of 50×50×20 nm3 is considered as single cell magnetic storage of magnetic random acces memory (MRAM). Thermally assisted magnetization reversal was performed by cooling writing process from near/almost Curie point to room temperature on 20 times runs for different randomly magnetized state. The results show that the probability reversal under zero magnetic field decreased with the increase of the energy barrier. The zero-field probability switching of 55% attained for energy barrier of 60 k B T and the reversal probability become zero noted at energy barrier of 2348 k B T. The higest zero-field switching probability of 55% attained for energy barrier of 60 k B T which corespond to magnetif field of 150 Oe for switching.

A Mechanistic Study of Arsenic (III) Rejection by Reverse Osmosis and Nanofiltration Membranes

ERIC Educational Resources Information Center

Suzuki, Tasuma

2009-01-01

Reverse osmosis/nanofiltration (RO/NF) membranes are capable to provide an effective barrier for a wide range of contaminants (including disinfection by-products precursors) in a single treatment step. However, solute rejection mechanisms by RO/NF membranes are not well understood. The lack of mechanistic information arises from experimental…

26 CFR 1.861-18 - Classification of transactions involving computer programs.

Code of Federal Regulations, 2011 CFR

2011-04-01

... on a single disk for a one-time payment with restrictions on transfer and reverse engineering, which... license. The license is stated to be perpetual. Under the license no reverse engineering, decompilation... fee, on a World Wide Web home page on the Internet. P, the Country Z resident, in return for payment...

26 CFR 1.861-18 - Classification of transactions involving computer programs.

Code of Federal Regulations, 2010 CFR

2010-04-01

... on a single disk for a one-time payment with restrictions on transfer and reverse engineering, which... license. The license is stated to be perpetual. Under the license no reverse engineering, decompilation... fee, on a World Wide Web home page on the Internet. P, the Country Z resident, in return for payment...

10 CFR 431.92 - Definitions concerning commercial air conditioners and heat pumps.

Code of Federal Regulations, 2012 CFR

2012-01-01

... mounting through the wall, and that is industrial equipment. It includes a prime source of refrigeration... utilizes reverse cycle refrigeration as its prime heat source, that has a supplementary heat source..., hot water, or gas, but may not include reverse cycle refrigeration as a heating means. Single package...

Engineering and Evolution of Molecular Chaperones and Protein Disaggregases with Enhanced Activity

PubMed Central

Mack, Korrie L.; Shorter, James

2016-01-01

Cells have evolved a sophisticated proteostasis network to ensure that proteins acquire and retain their native structure and function. Critical components of this network include molecular chaperones and protein disaggregases, which function to prevent and reverse deleterious protein misfolding. Nevertheless, proteostasis networks have limits, which when exceeded can have fatal consequences as in various neurodegenerative disorders, including Parkinson's disease and amyotrophic lateral sclerosis. A promising strategy is to engineer proteostasis networks to counter challenges presented by specific diseases or specific proteins. Here, we review efforts to enhance the activity of individual molecular chaperones or protein disaggregases via engineering and directed evolution. Remarkably, enhanced global activity or altered substrate specificity of various molecular chaperones, including GroEL, Hsp70, ClpX, and Spy, can be achieved by minor changes in primary sequence and often a single missense mutation. Likewise, small changes in the primary sequence of Hsp104 yield potentiated protein disaggregases that reverse the aggregation and buffer toxicity of various neurodegenerative disease proteins, including α-synuclein, TDP-43, and FUS. Collectively, these advances have revealed key mechanistic and functional insights into chaperone and disaggregase biology. They also suggest that enhanced chaperones and disaggregases could have important applications in treating human disease as well as in the purification of valuable proteins in the pharmaceutical sector. PMID:27014702

Simulation and analysis of vertical displacement characteristics of three wheels reverse trike vehicle with PID controller application

NASA Astrophysics Data System (ADS)

Wibowo, Lambang, Lullus; Erick Chandra, N.; Muhayat, Nurul; Jaka S., B.

2017-08-01

The purpose of this research is to obtain a mathematical model (Full Vehicle Model) and compare the performance of passive and active suspension systems of a Three-Wheels Reverse Trike vehicle. Vehicle suspension system should able to provide good steering handling and passenger comfort. Vehicle suspension system generally only uses passive suspension components with fix spring and damper coefficients. An active suspension developed from the traditional (passive) suspension design can directly control the actuator force in the suspension system. In this paper, modeling and simulation of passive and active suspension system for a Full Vehicle Model is performed using Simulink-MATLAB software. Ziegler & Nichols tuning method is used to obtain controller parameters of Proportional Integral Derivative (PID) controller. Comparison between passive and active suspension with PID controller is conducted for disturbances input of single bump road surface profile 0.1 meters. The results are the displacement and acceleration of the vehicle body in the vertical direction of active suspension system with PID control is better in providing handling capabilities and comfort for the driver than of passive suspension system. The acceleration of 1,8G with the down time of 2.5 seconds is smaller than the acceleration of 2.5G with down time of 5.5 seconds.

Voltage Drop in a Ferroelectric Single Layer Capacitor by Retarded Domain Nucleation.

PubMed

Kim, Yu Jin; Park, Hyeon Woo; Hyun, Seung Dam; Kim, Han Joon; Kim, Keum Do; Lee, Young Hwan; Moon, Taehwan; Lee, Yong Bin; Park, Min Hyuk; Hwang, Cheol Seong

2017-12-13

Ferroelectric (FE) capacitor is a critical electric component in microelectronic devices. Among many of its intriguing properties, the recent finding of voltage drop (V-drop) across the FE capacitor while the positive charges flow in is especially eye-catching. This finding was claimed to be direct evidence that the FE capacitor is in negative capacitance (NC) state, which must be useful for (infinitely) high capacitance and ultralow voltage operation of field-effect transistors. Nonetheless, the NC state corresponds to the maximum energy state of the FE material, so it has been widely accepted in the community that the material alleviates that state by forming ferroelectric domains. This work reports a similar V-drop effect from the 150 nm thick epitaxial BaTiO 3 ferroelectric thin film, but the interpretation was completely disparate; the V-drop can be precisely simulated by the reverse domain nucleation and propagation of which charge effect cannot be fully compensated for by the supplied charge from the external charge source. The disappearance of the V-drop effect was also observed by repeated FE switching only up to 10 cycles, which can hardly be explained by the involvement of the NC effect. The retained reverse domain nuclei even after the subsequent poling can explain such behavior.

Nonlinear dielectric effects in liquids: a guided tour

NASA Astrophysics Data System (ADS)

Richert, Ranko

2017-09-01

Dielectric relaxation measurements probe how the polarization of a material responds to the application of an external electric field, providing information on structure and dynamics of the sample. In the limit of small fields and thus linear response, such experiments reveal the properties of the material in the same thermodynamic state it would have in the absence of the external field. At sufficiently high fields, reversible changes in enthalpy and entropy of the system occur even at constant temperature, and these will in turn alter the polarization responses. The resulting nonlinear dielectric effects feature field induced suppressions (saturation) and enhancements (chemical effect) of the amplitudes, as well as time constant shifts towards faster (energy absorption) and slower (entropy reduction) dynamics. This review focuses on the effects of high electric fields that are reversible and observed at constant temperature for single component glass-forming liquids. The experimental challenges involved in nonlinear dielectric experiments, the approaches to separating and identifying the different sources of nonlinear behavior, and the current understanding of how high electric fields affect dielectric materials will be discussed. Covering studies from Debye’s initial approach to the present state-of-the-art, it will be emphasized what insight can be gained from the nonlinear responses that are not available from dielectric relaxation results obtained in the linear regime.

Oxfordian magnetostratigraphy of the Aguilón and Tosos sections (Iberian Range, Spain) and evidence of a pre-Oligocene overprint

NASA Astrophysics Data System (ADS)

Juárez, M. T.; Osete, M. L.; Meléndez, G.; Langereis, C. G.; Zijderveld, J. D. A.

1994-08-01

A composite magnetic polarity sequence has been constructed for the middle and late Oxfordian (late Jurassic) from four overlapping sections situated in both limbs of an anticline. Two stable magnetisation components could be isolated in every sample analyzed. Both components pass the fold test: a low-temperature secondary component, with Dec. = 340.9° and Inc. = 44.9° ( α95 = 1.7°), of pre-Oligocene age, showing always normal polarity, and a high-temperature primary component, with Dec. = 324.1° and Inc. = 40.6° (α 95 = 2.9°). The latter shows both normal and reversed polarities and provides the geomagnetic record for the late Jurassic. The magnetostratigraphy of the four overlapping sections has given consistent results and indicates that a high frequency of reversals characterises the pattern of the geomagnetic field during the middle to upper Oxfordian. The corresponding Oxfordian paleopole is Plat = 251.2°, Plong = 55.9° ( α95 = 3.1).

Optimal setups for forced-choice staircases with fixed step sizes.

PubMed

García-Pérez, M A

2000-01-01

Forced-choice staircases with fixed step sizes are used in a variety of formats whose relative merits have never been studied. This paper presents a comparative study aimed at determining their optimal format. Factors included in the study were the up/down rule, the length (number of reversals), and the size of the steps. The study also addressed the issue of whether a protocol involving three staircases running for N reversals each (with a subsequent average of the estimates provided by each individual staircase) has better statistical properties than an alternative protocol involving a single staircase running for 3N reversals. In all cases the size of a step up was different from that of a step down, in the appropriate ratio determined by García-Pérez (Vision Research, 1998, 38, 1861 - 1881). The results of a simulation study indicate that a) there are no conditions in which the 1-down/1-up rule is advisable; b) different combinations of up/down rule and number of reversals appear equivalent in terms of precision and cost: c) using a single long staircase with 3N reversals is more efficient than running three staircases with N reversals each: d) to avoid bias and attain sufficient accuracy, threshold estimates should be based on at least 30 reversals: and e) to avoid excessive cost and imprecision, the size of the step up should be between 2/3 and 3/3 the (known or presumed) spread of the psychometric function. An empirical study with human subjects confirmed the major characteristics revealed by the simulations.

NASA Researcher Examines an Aircraft Model with a Four-Fan Thrust Reverser

NASA Image and Video Library

1972-03-21

National Aeronautics and Space Administration (NASA) researcher John Carpenter inspects an aircraft model with a four-fan thrust reverser which would be studied in the 9- by 15-Foot Low Speed Wind Tunnel at the Lewis Research Center. Thrust reversers were introduced in the 1950s as a means for slowing high-speed jet aircraft during landing. Engineers sought to apply the technology to Vertical and Short Takeoff and Landing (VSTOL) aircraft in the 1970s. The new designs would have to take into account shorter landing areas, noise levels, and decreased thrust levels. A balance was needed between the thrust reverser’s efficiency, its noise generation, and the engine’s power setting. This model underwent a series of four tests in the 9- by 15-foot tunnel during April and May 1974. The model, with a high-wing configuration and no tail, was equipped with four thrust-reverser engines. The investigations included static internal aerodynamic tests on a single fan/reverser, wind tunnel isolated fan/reverser thrust tests, installation effects on a four-fan airplane model in a wind tunnel, and single reverser acoustic tests. The 9-by 15 was built inside the return leg of the 8- by 6-Foot Supersonic Wind Tunnel in 1968. The facility generates airspeeds from 0 to 175 miles per hour to evaluate the aerodynamic performance and acoustic characteristics of nozzles, inlets, and propellers, and investigate hot gas re-ingestion of advanced VSTOL concepts. John Carpenter was a technician in the Wind Tunnels Service Section of the Test Installations Division.

Is inhibitory control involved in discriminating pseudowords that contain the reversible letters b and d?

PubMed

Brault Foisy, Lorie-Marlène; Ahr, Emmanuel; Masson, Steve; Houdé, Olivier; Borst, Grégoire

2017-10-01

Children tend to confuse reversible letters such as b and d when they start learning to read. According to some authors, mirror errors are a consequence of the mirror generalization (MG) process that allows one to recognize objects independently of their left-right orientation. Although MG is advantageous for the visual recognition of objects, it is detrimental for the visual recognition of reversible letters. Previous studies comparing novice and expert readers demonstrated that MG must be inhibited to discriminate reversible single letters. In this study, we investigated whether MG must also be inhibited by novice readers to discriminate between two pseudowords containing reversible letters. Readable pseudowords, rather than words, were used to mimic early non-automatic stages of reading when reading is achieved by decoding words through grapheme-phoneme pairing and combination. We designed a negative priming paradigm in which school-aged children (10-year-olds) were asked to judge whether two pseudowords were identical on the prime and whether two animals were identical on the probe. Children required more time to determine that two animals were mirror images of each other when preceded by pseudowords containing the reversible letter b or d than when preceded by different pseudowords containing the control letter f or t (Experiment 1) or by different pseudowords that differed only by the target letter f or k (Experiment 2). These results suggest that MG must be inhibited to discriminate between pseudowords containing reversible letters, generalizing the findings regarding single letters to a context more representative of the early stages of reading. Copyright © 2017 Elsevier Inc. All rights reserved.

Estimating Intervention Effects across Different Types of Single-Subject Experimental Designs: Empirical Illustration

ERIC Educational Resources Information Center

Moeyaert, Mariola; Ugille, Maaike; Ferron, John M.; Onghena, Patrick; Heyvaert, Mieke; Beretvas, S. Natasha; Van den Noortgate, Wim

2015-01-01

The purpose of this study is to illustrate the multilevel meta-analysis of results from single-subject experimental designs of different types, including AB phase designs, multiple-baseline designs, ABAB reversal designs, and alternating treatment designs. Current methodological work on the meta-analysis of single-subject experimental designs…

A reversible single-molecule switch based on activated antiaromaticity

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

Yin, Xiaodong; Zang, Yaping; Zhu, Liangliang

Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope–based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivativemore » that switches to an antiaromatic state with 6-4-6-p electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.« less

A reversible single-molecule switch based on activated antiaromaticity

DOE PAGES

Yin, Xiaodong; Zang, Yaping; Zhu, Liangliang; ...

2017-10-27

Single-molecule electronic devices provide researchers with an unprecedented ability to relate novel physical phenomena to molecular chemical structures. Typically, conjugated aromatic molecular backbones are relied upon to create electronic devices, where the aromaticity of the building blocks is used to enhance conductivity. We capitalize on the classical physical organic chemistry concept of Hückel antiaromaticity by demonstrating a single-molecule switch that exhibits low conductance in the neutral state and, upon electrochemical oxidation, reversibly switches to an antiaromatic high-conducting structure. We form single-molecule devices using the scanning tunneling microscope–based break-junction technique and observe an on/off ratio of ~70 for a thiophenylidene derivativemore » that switches to an antiaromatic state with 6-4-6-p electrons. Through supporting nuclear magnetic resonance measurements, we show that the doubly oxidized core has antiaromatic character and we use density functional theory calculations to rationalize the origin of the high-conductance state for the oxidized single-molecule junction. Together, our work demonstrates how the concept of antiaromaticity can be exploited to create single-molecule devices that are highly conducting.« less

Reverse Flow Engine Core Having a Ducted Fan with Integrated Secondary Flow Blades

NASA Technical Reports Server (NTRS)

Kisska, Michael K. (Inventor); Princen, Norman H. (Inventor); Kuehn, Mark S. (Inventor); Cosentino, Gary B. (Inventor)

2014-01-01

Secondary air flow is provided for a ducted fan having a reverse flow turbine engine core driving a fan blisk. The fan blisk incorporates a set of thrust fan blades extending from an outer hub and a set of integral secondary flow blades extending intermediate an inner hub and the outer hub. A nacelle provides an outer flow duct for the thrust fan blades and a secondary flow duct carries flow from the integral secondary flow blades as cooling air for components of the reverse flow turbine engine.

Sleep Duration and Midday Napping with 5-Year Incidence and Reversion of Metabolic Syndrome in Middle-Aged and Older Chinese.

PubMed

Yang, Liangle; Xu, Zengguang; He, Meian; Yang, Handong; Li, Xiulou; Min, Xinwen; Zhang, Ce; Xu, Chengwei; Angileri, Francesca; Légaré, Sébastien; Yuan, Jing; Miao, Xiaoping; Guo, Huan; Yao, Ping; Wu, Tangchun; Zhang, Xiaomin

2016-11-01

Prospective evidence on the association of sleep duration and midday napping with metabolic syndrome (MetS) is limited. We aimed to examine the associations of sleep duration and midday napping with risk of incidence and reversion of MetS and its components among a middle-aged and older Chinese population. We included 14,399 subjects from the Dongfeng-Tongji (DFTJ) Cohort Study (2008-2013) who were free of coronary heart disease, stroke, and cancer at baseline. Baseline data were obtained by questionnaires and health examinations. Odds ratios (ORs) and 95% confidence interval (CI) were derived from multivariate logistic regression models. After controlling for potential covariates, longer sleep duration (≥ 9 h) was associated with a higher risk of MetS incidence (OR, 1.29; 95% CI, 1.08-1.55) and lower reversion of MetS (OR, 0.80; 95% CI, 0.66-0.96) compared with sleep duration of 7 to < 8 h; whereas shorter sleep duration (< 6 h) was not related to incidence or reversion of MetS. For midday napping, subjects with longer napping (≥ 90 min) was also associated with a higher risk of MetS incidence and a lower risk of MetS reversion compared with those with napping of 1 to < 30 min (OR, 1.48; 95% CI, 1.05-2.10 and OR, 0.70; 95% CI, 0.52-0.94, respectively). Significance for incidence or reversion of certain MetS components remained in shorter and longer sleepers but disappeared across napping categories. Both longer sleep duration and longer midday napping were potential risk factors for MetS incidence, and concurrently exert adverse effects on MetS reversion. © 2016 Associated Professional Sleep Societies, LLC.

Modulation of hepatic stellate cells and reversibility of hepatic fibrosis

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

Huang, Yu, E-mail: 1293363632@QQ.com; Deng, Xin, E-mail: Hendly@163.com; Liang, Jian, E-mail: lj99669@163.com

Hepatic fibrosis (HF) is the pathological component of a variety of chronic liver diseases. Hepatic stellate cells (HSC) are the main collagen-producing cells in the liver and their activation promotes HF. If HSC activation and proliferation can be inhibited, HF occurrence and development can theoretically be reduced and even reversed. Over the past ten years, a number of studies have addressed this process, and here we present a review of HSC modulation and HF reversal. - Highlights: • We present a review of the modulation of hepatic stellate cells (HSC) and reversibility of hepatic fibrosis (HF). • HSC are themore » foci of HF occurrence and development, HF could be prevented and treated by modulating HSC. • If HSC activation and proliferation can be inhibited, HF could theoretically be inhibited and even reversed. • Prevention or reversal of HSC activation, or promotion of HSC apoptosis, immune elimination, and senescence may prevent, inhibit or reverse HF.« less

Wave interference: mechanics of the standing wave component and the illusion of "which way" information

NASA Astrophysics Data System (ADS)

Hudgins, W. R.; Meulenberg, A.; Penland, R. F.

2015-09-01

Two adjacent coherent light beams, 180° out of phase and traveling on adjacent, parallel paths, remain visibly separated by the null (dark) zone from their mutual interference pattern as they merge. Each half of the pattern can be traced to one of the beams. Does such an experiment provide both "which way" and momentum knowledge? To answer this question, we demonstrate, by examining behavior of wave momentum and energy in a medium, that interfering waves interact. Central to the mechanism of interference is a standing wave component resulting from the combination of coherent waves. We show the mathematics for the formation of the standing wave component and for wave momentum involved in the waves' interaction. In water and in open coaxial cable, we observe that standing waves form cells bounded "reflection zones" where wave momentum from adjacent cells is reversed, confining oscillating energy to each cell. Applying principles observed in standing waves in media to the standing wave component of interfering light beams, we identify dark (null) regions to be the reflection zones. Each part of the interference pattern is affected by interactions between other parts, obscuring "which-way" information. We demonstrated physical interaction experimentally using two beams interfering slightly with one dark zone between them. Blocking one beam "downstream" from the interference region removed the null zone and allowed the remaining beam to evolve to a footprint of a single beam.

The fifth electron in the fully reduced caa(3) from Thermus thermophilus is competent in proton pumping.

PubMed

Siletsky, Sergey A; Belevich, Ilya; Soulimane, Tewfik; Verkhovsky, Michael I; Wikström, Mårten

2013-01-01

The time-resolved kinetics of membrane potential generation coupled to oxidation of the fully reduced (five-electron) caa(3) cytochrome oxidase from Thermus thermophilus by oxygen was studied in a single-turnover regime. In order to calibrate the number of charges that move across the vesicle membrane in the different reaction steps, the reverse electron transfer from heme a(3) to heme a and further to the cytochrome c/Cu(A) has been resolved upon photodissociation of CO from the mixed valence enzyme in the absence of oxygen. The reverse electron transfer from heme a(3) to heme a and further to the cytochrome c/Cu(A) pair is resolved as a single transition with τ~40 μs. In the reaction of the fully reduced cytochrome caa(3) with oxygen, the first electrogenic phase (τ~30 μs) is linked to OO bond cleavage and generation of the P(R) state. The next electrogenic component (τ~50 μs) is associated with the P(R)→F transition and together with the previous reaction step it is coupled to translocation of about two charges across the membrane. The three subsequent electrogenic phases, with time constants of ~0.25 ms, ~1.4 ms and ~4 ms, are linked to the conversion of the binuclear center through the F→O(H)→E(H) transitions, and result in additional transfer of four charges through the membrane dielectric. This indicates that the delivery of the fifth electron from heme c to the binuclear center is coupled to pumping of an additional proton across the membrane. Copyright © 2012 Elsevier B.V. All rights reserved.

Enantiopure heterobimetallic single-chain magnets from the chiral Ru(III) building block.

PubMed

Ru, Jing; Gao, Feng; Wu, Tao; Yao, Min-Xia; Li, Yi-Zhi; Zuo, Jing-Lin

2014-01-21

A pair of one-dimensional enantiomers based on the versatile chiral dicyanoruthenate(III) building block have been synthesized and they are chiral single-chain magnets with the effective spin-reversal barrier of 28.2 K.

Probing the interior of a solid volume with time reversal and nonlinear elastic wave spectroscopy.

PubMed

Le Bas, P Y; Ulrich, T J; Anderson, B E; Guyer, R A; Johnson, P A

2011-10-01

A nonlinear scatterer is simulated in the body of a sample and demonstrates a technique to locate and define the elastic nature of the scatterer. Using the principle of time reversal, elastic wave energy is focused at the interface between blocks of optical grade glass and aluminum. Focusing of energy at the interface creates nonlinear wave scattering that can be detected on the sample perimeter with time-reversal mirror elements. The nonlinearly generated scattered signal is bandpass filtered about the nonlinearly generated components, time reversed and broadcast from the same mirror elements, and the signal is focused at the scattering location on the interface. © 2011 Acoustical Society of America

Interactions and reversal-field memory in complex magnetic nanowire arrays

NASA Astrophysics Data System (ADS)

Rotaru, Aurelian; Lim, Jin-Hee; Lenormand, Denny; Diaconu, Andrei; Wiley, John. B.; Postolache, Petronel; Stancu, Alexandru; Spinu, Leonard

2011-10-01

Interactions and magnetization reversal of Ni nanowire arrays have been investigated by the first-order reversal curve (FORC) method. Several series of samples with controlled spatial distribution were considered including simple wires of different lengths and diameters (70 and 110 nm) and complex wires with a single modulated diameter along their length. Subtle features of magnetic interactions are revealed through a quantitative analysis of the local interaction field profile distributions obtained from the FORC method. In addition, the FORC analysis indicates that the nanowire systems with a mean diameter of 70 nm appear to be organized in symmetric clusters indicative of a reversal-field memory effect.

Making the Grade: Reversing Childhood Obesity in School Districts Toolkit--What Is It?

ERIC Educational Resources Information Center

Robert Wood Johnson Foundation, 2012

2012-01-01

In order to reverse the childhood obesity epidemic in the United States, it is critical to elevate the importance of physical education and physical activity as core components of a comprehensive curriculum in schools. It is also essential to explicitly state ways in which the reauthorization of the Elementary and Secondary Education Act (ESEA)…

Magnetic interactions in anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer magnets

NASA Astrophysics Data System (ADS)

Dai, Z. M.; Liu, W.; Zhao, X. T.; Han, Z.; Kim, D.; Choi, C. J.; Zhang, Z. D.

2016-10-01

The magnetic properties and the possible interaction mechanisms of anisotropic soft- and hard-magnetic multilayers have been investigated by altering the thickness of different kinds of spacer layers. The metal Ta and the insulating oxides MgO, Cr2O3 have been chosen as spacer layers to investigate the characteristics of the interactions between soft- and hard-magnetic layers in the anisotropic Nd-Dy-Fe-Co-B/α-Fe multilayer system. The dipolar and exchange interaction between hard and soft phases are evaluated with the help of the first order reversal curve method. The onset of the nucleation field and the magnetization reversal by domain wall movement are also evident from the first-order-reversal-curve measurements. Reversible/irreversible distributions reveal the natures of the soft- and hard-magnetic components. Incoherent switching fields are observed and the calculations show the semiquantitative contributions of hard and soft components to the system. An antiferromagnetic spacer layer will weaken the interaction between ferromagnetic layers and the effective interaction length decreases. As a consequence, the dipolar magnetostatic interaction may play an important role in the long-range interaction in anisotropic multilayer magnets.

Magnetization reversal processes in bonded magnets made from a mixture of Nd-(Fe,Co)-B and strontium ferrite powders

NASA Astrophysics Data System (ADS)

Dospial, M.; Plusa, D.

2013-03-01

Isotropic epoxy-resin bonded magnets composed of different amounts of Magnequench MQP-B and strontium ferrite powders have been prepared using a compression molding technique. The magnetic parameters for magnets with different amounts of strontium ferrite and magnetization reversal processes have been studied by the measurement of the initial magnetization curves, the major hysteresis loops measured at a field up to 14 T and sets of recoil loops. The enhancement of μ0MR and μ0HC is observed in comparison with the calculated values. From the recoil loops the field dependences of the reversible, irreversible and total magnetization components and the differential susceptibilities were derived. From the dependence of the irreversible magnetization component versus an applied field it was deduced that the main mechanism of magnetization reversal process is the pinning of domain walls in MQP-B and strontium ferrite grains. The interactions between the magnetic particles and grains have been examined by the analysis of the δM plot. The δM behavior of magnets with ferrite has been interpreted as being composed of magnetizing exchange coupling and demagnetizing dipolar interactions.

Photoinduced reversible lattice expansion in W-doped TiO2 through the change of its electronic structure

NASA Astrophysics Data System (ADS)

Feng, Fan; Yang, Weiyi; Gao, Shuang; Zhu, Linggang; Li, Qi

2018-02-01

External stimulations of applied force or voltage have been reported to induce crystal lattice dimension changes with the order of 0.1% or above by imposing external mechanical or electric forces on atoms forming the lattice for various types of materials, including oxides, metals, polymers, and carbon nanostructures. As far as we know, however, no report is available for similar level changes in oxides from their internal electronic structure changes induced by photoirradiation. We show that reversible lattice expansion comparable to those by applied force or voltage can be induced by UV-irradiation on an oxide of W-doped TiO2 nanotubes through the reversible changes of its internal electronic structure by the accumulation and release of photogenerated electrons in W-dopants when UV-illumination is on and off. This photoirradiation-induced reversible lattice expansion and subsequent optical, electric, and magnetic property changes may also be present in other material systems by proper material design if they possess one component that is able to produce electrons upon photoirradiation and the other component that is able to accumulate photogenerated electrons to induce lattice changes and release them after the photoirradiation is off.

Fully gapped superconductivity in single crystals of noncentrosymmetric Re6Zr with broken time-reversal symmetry

NASA Astrophysics Data System (ADS)

Pang, G. M.; Nie, Z. Y.; Wang, A.; Singh, D.; Xie, W.; Jiang, W. B.; Chen, Y.; Singh, R. P.; Smidman, M.; Yuan, H. Q.

2018-06-01

The noncentrosymmetric superconductor Re6Zr has attracted much interest due to the observation of broken time-reversal symmetry in the superconducting state. Here we report an investigation of the superconducting gap structure of Re6Zr single crystals by measuring the magnetic penetration depth shift Δ λ (T ) and electronic specific heat Ce(T ) . Δ λ (T ) exhibits an exponential temperature dependence behavior for T ≪Tc , which indicates a fully open superconducting gap. Our analysis shows that a single gap s -wave model is sufficient to describe both the superfluid density ρs(T ) and Ce(T ) results, with a fitted gap magnitude larger than the weak coupling BCS value, providing evidence for fully gapped superconductivity in Re6Zr with moderate coupling.

Reversing and nonreversing heat capacity of poly(lactic acid) in the glass transition region by TMDSC

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

Pyda, Marek; Wunderlich, Bernhard

2005-11-01

A study of the glass transition of an amorphous and a semicrystalline poly(lactic acid) (PLA) is performed with adiabatic calorimetry, differential scanning calorimetry (DSC), and temperature-modulated DSC (TMDSC). The reversing, total, and nonreversing apparent heat capacities of samples with different contents of L- and D-lactic acid and with various thermal histories were evaluated. Different modes of TMDSC analyses of amorphous and semicrystalline PLA were compared to the total heat capacity from standard DSC. The enthalpy relaxation and the cold crystallization in the glass transition region are largely irreversible. The melting is largely irreversible, but a 100% reversing fraction is observedmore » at low temperatures from 375 to 420 K, which becomes small inside the major melting peak at about 440 K. From the TMDSC of amorphous PLA, the combined information on endothermic and exothermic enthalpy relaxation and glass transition were deconvoluted into the reversing and nonreversing components. The glass transition temperature from the reversing heat capacity and the enthalpy relaxation peaks from the nonreversing component shift to higher temperature for increasingly annealed PLA. The relaxation times for aging decrease on cooling until the glass transition is reached and then increase. This behavior is linked to cooperativity. All quantitative thermal analyses are based on the heat capacity of the solid and liquid, evaluated earlier with the advanced thermal analysis system (ATHAS).« less

Shape Memory effect and Superelasticity in the [001] Single crystals of a FeNiCoAlTa Alloy with γ-α'-Thermoelastic Martensitic Transformations

NASA Astrophysics Data System (ADS)

Chumlyakov, Yu. I.; Kireeva, I. V.; Kretinina, I. V.; Keinikh, K. S.; Kuts, O. A.; Kirillov, V. A.; Karaman, I.; Maier, H.

2013-12-01

Using single crystals of a Fe - 28% Ni - 17% Co - 11.5% Al - 25% Ta (аt.%) alloy, oriented for tensile loading along the [001] direction, the shape-memory (SME) and superelasticity (SE) effects caused by reversible thermoelastic martensitic transformations (MTs) from a high-temperature fcc-phase into a bctmartensite are investigated. It is demonstrated that the conditions necessary for the thermoelastic MTs to occur are achieved by aging at 973 K within the time interval (t) from 0.5 to 7.0 hours, which is accompanied by precipitation of the γ'-phase particles, (FeNiCo)3(AlTa), whose d < 8-12 nm. When the size of the γ'-precipitates becomes as large as d ≥ 8-12 nm, the MT becomes partially reversible. The physical causes underlying the kinetics of thermoelstic reversible fcc-bct MTs are discussed.

An attempt to determine the absolute geomagnetic field intensity in Southwestern Iceland during the Gauss-Matuyama reversal

NASA Astrophysics Data System (ADS)

Goguitchaichvili, Avto; Prévot, Michel; Thompson, John; Roberts, Neil

1999-08-01

We have measured the variation in the intensity of the geomagnetic field during the Gauss-Matuyama (N4-R3) polarity reversal by application of the Thelliers' method to specimens of lava flows from Hvalfjördur district in Western Iceland (Reynivallahals Mts.). Eleven lava flows all show very similar directions corresponding to an equatorial VGP (Plat=2.9°N, Plong=81.9°E, A95=4.2, K=119). Twenty-nine specimens from nine of the flows were pre-selected for palaeointensity determination on the basis that specimens from the same drill cores showed a single component of magnetisation upon thermal or AF demagnetisation, and possessed low magnetic viscosity and reversible susceptibility curves upon heating at 600-650°C. Observation that the directional data obtained in the course of the palaeointensity experiments occasionally showed substantial non-linearity indicates that a significant chemical remanent magnetization (CRM) can be acquired in the direction of the laboratory field during heating at T. For each double heating step we calculated the ratio of CRM( T) to the magnitude of the natural remanent magnetization (NRM( T)) in the direction of characteristic remanence (obtained independently from another specimen from the same core). When this ratio exceeded 15%, the paleointensity data was rejected. In addition, specimens for which the quality factor was less than 5 were rejected. Twelve reliable palaeointensity values were obtained from specimens representing five lava flows. The results confirm that the palaeointensity was substantially reduced during the N4-R3 reversal. The range of mean palaeointensity values obtained for the five flows is 8.8 to 20.5 and the overall mean is 14.8±4.6 μT. This corresponds to an equivalent VDM of 3.81±1.19 (10 22 A m 2). A comparison of all Thellier palaeointensity data from the R3 magnetozone in the Rayinivallahals Mts. area reveals a progressive although irregular increase in the palaeointensity between the Gauss-Matuyama and Matuyama-Réunion reversals. This trend is opposite to that expected from the saw tooth model of palaeointensity variations.

Encoding changes in orbitofrontal cortex in reversal-impaired aged rats.

PubMed

Schoenbaum, Geoffrey; Setlow, Barry; Saddoris, Michael P; Gallagher, Michela

2006-03-01

Previous work in rats and primates has shown that normal aging can be associated with a decline in cognitive flexibility mediated by prefrontal circuits. For example, aged rats are impaired in rapid reversal learning, which in young rats depends critically on the orbitofrontal cortex. To assess whether aging-related reversal impairments reflect orbitofrontal dysfunction, we identified aged rats with reversal learning deficits and then recorded single units as these rats, along with unimpaired aged cohorts and young control rats, learned and reversed a series of odor discrimination problems. We found that the flexibility of neural correlates in orbitofrontal cortex was markedly diminished in aged rats characterized as reversal-impaired in initial training. In particular, although many cue-selective neurons in young and aged-unimpaired rats reversed odor preference when the odor-outcome associations were reversed, cue-selective neurons in reversal-impaired aged rats did not. In addition, outcome-expectant neurons in aged-impaired rats failed to become active during cue sampling after learning. These altered features of neural encoding could provide a basis for cognitive inflexibility associated with normal aging.

Calcium channels in solitary retinal ganglion cells from post-natal rat.

PubMed Central

Karschin, A; Lipton, S A

1989-01-01

1. Calcium currents from identified, post-natal retinal ganglion cell neurones from rat were studied with whole-cell and single-channel patch-clamp techniques. Na+ and K+ currents were suppressed with pharmacological agents, allowing isolation of current carried by either 10 mM-Ca2+ or Ba2- during whole-cell recordings. For cell-attached patch recordings, the recording pipette contained 96-110 mM-BaCl2 while the bath solution consisted of isotonic potassium aspartate in order to zero the neuronal membrane potential. 2. A transient component, present in approximately one-third of the whole-cell recordings resembles closely the T-type calcium current observed previously in other tissues. This component activates at low voltages (-40 to -50 mV from holding potentials negative to -80 mV), inactivates with a time constant of 10-30 ms at 35 degrees C, and is carried equally well by Ba2+ or Ca2+. In single-channel recordings small (8 pS) channels are observed whose aggregate microscopic kinetics correspond well to the macroscopic current obtained during whole-cell measurements. 3. During whole-cell recordings, a more prolonged component activates in all retinal ganglion cells at -40 to -20 mV from a holding potential of -90 mV. This component is substantially larger when equimolar Ba2+ replaces Ca2+ as the charge carrier, and is sensitive to the dihydropyridine agonist Bay K8644 (5 microM) and antagonists nifedipine (1-10 microM) and nimodipine (1-10 microM). Thus, the dihydropyridine pharmacology of this prolonged component resembles that of the L-type calcium current found in dorsal root ganglion neurones and in heart cells. Also reminiscent of the L-current, the prolonged component in this preparation is less inactivated at depolarized holding potentials (-60 to -40 mV) than the transient component. In cell-attached recordings, large (20 pS) channels are observed with activation properties similar to those of the prolonged portion of the whole-cell current. 4. omega-Conotoxin fraction GVIA (omega-CgTX VIA), a peptide from the venom of the snail Conus geographus, produces a readily reversible blockade of all components of the calcium current in these central mammalian neurones. This finding is in contrast to that of other preparations in which this toxin is responsible for an ephemeral block of T-current but a long-lasting block of other components of calcium current. 5. In summary, at least two components of calcium current with discrete underlying unitary events are present in post-natal retinal ganglion cells from rat. One component closely resembles the T or transient current observed in other cell types.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2559971

Influence of glenoid component design and humeral component retroversion on internal and external rotation in reverse shoulder arthroplasty: a cadaver study.

PubMed

Berhouet, J; Garaud, P; Favard, L

2013-12-01

A common disadvantage of reverse shoulder arthroplasty is limitation of the range of arm rotation. Several changes to the prosthesis design and implantation technique have been suggested to improve rotation range of motion (ROM). Glenoid component design and degree of humeral component retroversion influence rotation ROM after reverse shoulder arthroplasty. The Aequalis Reversed™ shoulder prosthesis (Tornier Inc., Edina, MN, USA) was implanted into 40 cadaver shoulders. Eight glenoid component combinations were tested, five with the 36-mm sphere (centred seating, eccentric seating, inferior tilt, centred with a 5-mm thick lateralised spacer, and centred with a 7-mm thick lateralised spacer) and three with the 42-mm sphere (centred with no spacer or with a 7-mm or 10-mm spacer). Humeral component position was evaluated with 0°, 10°, 20°, 30°, and 40° of retroversion. External and internal rotation ROMs to posterior and anterior impingement on the scapular neck were measured with the arm in 20° of abduction. The large glenosphere (42 mm) was associated with significantly (P<0.05) greater rotation ROMs, particularly when combined with a lateralised spacer (46° internal and 66° external rotation). Rotation ROMs were smallest with the 36-mm sphere. Greater humeral component retroversion was associated with a decrease in internal rotation and a significant increase (P<0.05) in external rotation. The best balance between rotation ROMs was obtained with the native retroversion, which was estimated at 17.5° on average in this study. Our anatomic study in a large number of cadavers involved a detailed and reproducible experimental protocol. However, we did not evaluate the variability in scapular anatomy. Earlier studies of the influence of technical parameters did not take humeral component retroversion into account. In addition, no previous studies assessed rotation ROMs. Rotation ROM should be improved by the use of a large-diameter glenosphere with a spacer to lateralise the centre of rotation of the gleno-humeral joint, as well as by positioning the humeral component at the patient's native retroversion value. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Are the Concepts of Dynamic Equilibrium and the Thermodynamic Criteria for Spontaneity, Nonspontaneity, and Equilibrium Compatible?

ERIC Educational Resources Information Center

Silverberg, Lee J.; Raff, Lionel M.

2015-01-01

Thermodynamic spontaneity-equilibrium criteria require that in a single-reaction system, reactions in either the forward or reverse direction at equilibrium be nonspontaneous. Conversely, the concept of dynamic equilibrium holds that forward and reverse reactions both occur at equal rates at equilibrium to the extent allowed by kinetic…

Design and Assessment of a Real Time Reverse Transcription-PCR Method to Genotype Single-Stranded RNA Male-Specific Coliphages (Family Leviviridae).

EPA Science Inventory

A real-time, reverse transcription-PCR (RT-qPCR) assay was developed to differentiate the four genogroups of male-specific ssRNA coliphages (FRNA) (family Leviviridae). As FRNA display a trend of source-specificity (human sewage or animal waste) at the genogroup level, this assa...

Novel Structure of Ty3 Reverse Transcriptase | Center for Cancer Research

Cancer.gov

Retrotransposons are mobile genetic elements that self amplify via a single-stranded RNA intermediate, which is converted to double-stranded DNA by an encoded reverse transcriptase (RT) with both DNA polymerase (pol) and ribonuclease H (RNase) activities. Categorized by whether they contain flanking long terminal repeat (LTR) sequences, retrotransposons play a critical role in

Computing Relative Free Energies of Solvation Using Single Reference Thermodynamic Integration Augmented with Hamiltonian Replica Exchange

DTIC Science & Technology

2010-10-21

paper assess the reversible works needed to alchemi - cally change each molecule to the benzene core reference state. To automate the alchemical...the alchemi - cal free energies or reversible works, the TI procedure split the interval from the real state of the molecule at λ ) 0 to the reference

EFFECTS OF REVERSE OSMOSIS ISOLATION ON REACTIVITY OF NATURALLY OCCURRING DISSOLVED ORGANIC MATTER IN PHYSICOCHEMICAL PROCESSES. (R828045)

EPA Science Inventory

A field reverse osmosis system was used to isolate dissolved organic matter (DOM) from two lacustrine and two riverine surface water sources. The rejection of DOM was on the order of 99% and did not vary significantly with pressure. A simple mass balance model using a single m...

X-Ray analysis of riverbank sediment of the Tisza (Hungary): identification of particles from a mine pollution event

NASA Astrophysics Data System (ADS)

Osán, J.; Kurunczi, S.; Török, S.; Van Grieken, R.

2002-03-01

A serious heavy metal pollution of the Tisza River occurred on March 10, 2000, arising from a mine-dumping site in Romania. Sediment samples were taken from the main riverbed at six sites in Hungary, on March 16, 2000. The objective of this work was to distinguish the anthropogenic and crustal erosion particles in the river sediment. The samples were investigated using both bulk X-ray fluorescence (XRF) and thin-window electron probe microanalysis (EPMA). For EPMA, a reverse Monte Carlo method calculated the quantitative elemental composition of each single sediment particle. A high abundance of pyrite type particles was observed in some of the samples, indicating the influence of the mine dumps. Backscattered electron images proved that the size of particles with a high atomic number matrix was in the range of 2 μm. In other words the pyrites and the heavy elements form either small particles or are fragments of larger agglomerates. The latter are formed during the flotation process of the mines or get trapped to the natural crustal erosion particles. The XRF analysis of pyrite-rich samples always showed much higher Cu, Zn and Pb concentrations than the rest of the samples, supporting the conclusions of the single-particle EPMA results. In the polluted samples, the concentration of Cu, Zn and Pb reached 0.1, 0.3 and 0.2 wt.%, respectively. As a new approach, the abundance of particle classes obtained from single-particle EPMA and the elemental concentration obtained by XRF were merged into one data set. The dimension of the common data set was reduced by principal component analysis. The first component was determined by the abundance of pyrite and zinc sulfide particles and the concentration of Cu, Zn and Pb. The polluted samples formed a distinct group in the principal component space. The same result was supported by powder diffraction data. These analytical data combined with Earth Observation Techniques can be further used to estimate the quantity of particles originating from mine tailings on a defined river section.

Quantitation of triacylglycerols in edible oils by off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column.

PubMed

Wei, Fang; Hu, Na; Lv, Xin; Dong, Xu-Yan; Chen, Hong

2015-07-24

In this investigation, off-line comprehensive two-dimensional liquid chromatography-atmospheric pressure chemical ionization mass spectrometry using a single column has been applied for the identification and quantification of triacylglycerols in edible oils. A novel mixed-mode phenyl-hexyl chromatographic column was employed in this off-line two-dimensional separation system. The phenyl-hexyl column combined the features of traditional C18 and silver-ion columns, which could provide hydrophobic interactions with triacylglycerols under acetonitrile conditions and can offer π-π interactions with triacylglycerols under methanol conditions. When compared with traditional off-line comprehensive two-dimensional liquid chromatography employing two different chromatographic columns (C18 and silver-ion column) and using elution solvents comprised of two phases (reversed-phase/normal-phase) for triacylglycerols separation, the novel off-line comprehensive two-dimensional liquid chromatography using a single column can be achieved by simply altering the mobile phase between acetonitrile and methanol, which exhibited a much higher selectivity for the separation of triacylglycerols with great efficiency and rapid speed. In addition, an approach based on the use of response factor with atmospheric pressure chemical ionization mass spectrometry has been developed for triacylglycerols quantification. Due to the differences between saturated and unsaturated acyl chains, the use of response factors significantly improves the quantitation of triacylglycerols. This two-dimensional liquid chromatography-mass spectrometry system was successfully applied for the profiling of triacylglycerols in soybean oils, peanut oils and lord oils. A total of 68 triacylglycerols including 40 triacylglycerols in soybean oils, 50 triacylglycerols in peanut oils and 44 triacylglycerols in lord oils have been identified and quantified. The liquid chromatography-mass spectrometry data were analyzed using principal component analysis. The results of the principal component analysis enabled a clear identification of different plant oils. By using this two-dimensional liquid chromatography-mass spectrometry system coupled with principal component analysis, adulterated soybean oils with 5% added lord oil and peanut oils with 5% added soybean oil can be clearly identified. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of the single and combined treatment with dopamine agonist, somatostatin analog and mTOR inhibitors in a human lung carcinoid cell line: an in vitro study.

PubMed

Pivonello, Claudia; Rousaki, Panagoula; Negri, Mariarosaria; Sarnataro, Maddalena; Napolitano, Maria; Marino, Federica Zito; Patalano, Roberta; De Martino, Maria Cristina; Sciammarella, Concetta; Faggiano, Antongiulio; Rocco, Gaetano; Franco, Renato; Kaltsas, Gregory A; Colao, Annamaria; Pivonello, Rosario

2017-06-01

Somatostatin analogues and mTOR inhibitors have been used as medical therapy in lung carcinoids with variable results. No data are available on dopamine agonists as treatment for lung carcinoids. The main aim of the current study was to evaluate the effect of the combined treatment of somatostatin analogue octreotide and the dopamine agonist cabergoline with mTOR inhibitors in an in vitro model of typical lung carcinoids: the NCI-H727 cell line. In NCI-H727 cell line, reverse transcriptase-quantitative polymerase chain reaction and immunofluorescence were assessed to characterize the expression of the somatostatin receptor 2 and 5, dopamine receptor 2 and mTOR pathway components. Fifteen typical lung carcinoids tissue samples have been used for somatostatin receptor 2, dopamine receptor 2, and the main mTOR pathway component p70S6K expression and localization by immunohistochemistry. Cell viability, fluorescence-activated cell sorting analysis and western blot have been assessed to test the pharmacological effects of octreotide, cabergoline and mTOR inhibitors, and to evaluate the activation of specific cell signaling pathways in NCI-H727 cell line. NCI-H727 cell line expressed somatostatin receptor 2, somatostatin receptor 5 and dopamine receptor 2 and all mTOR pathway components at messenger and protein levels. Somatostatin receptor 2, dopamine receptor 2, and p70S6K (non phosphorylated and phosphorylated) proteins were expressed in most typical lung carcinoids tissue samples. Octreotide and cabergoline did not reduce cell viability as single agents but, when combined with mTOR inhibitors, they potentiate mTOR inhibitors effect after long-term exposure, reducing Akt and ERK phosphorylation, mTOR escape mechanisms, and increasing the expression DNA-damage-inducible transcript 4, an mTOR suppressor. In conclusion, the single use of octreotide and cabergoline is not sufficient to block cell viability but the combined approach of these agents with mTOR inhibitors might reduce the mTOR inhibitors-induced escape mechanisms and/or activate the endogenous mTOR suppressor, potentiating the effect of the mTOR inhibitors in an in vitro model of typical lung carcinoids.

Effect of varying internal geometry on the static performance of rectangular thrust-reverser ports

NASA Technical Reports Server (NTRS)

Re, Richard J.; Mason, Mary L.

1987-01-01

An investigation has been conducted to evaluate the effects of several geometric parameters on the internal performance of rectangular thrust-reverser ports for nonaxisymmetric nozzles. Internal geometry was varied with a test apparatus which simulated a forward-flight nozzle with a single, fully deployed reverser port. The test apparatus was designed to simulate thrust reversal (conceptually) either in the convergent section of the nozzle or in the constant-area duct just upstream of the nozzle. The main geometric parameters investigated were port angle, port corner radius, port location, and internal flow blocker angle. For all reverser port geometries, the port opening had an aspect ratio (throat width to throat height) of 6.1 and had a constant passage area from the geometric port throat to the exit. Reverser-port internal performance and thrust-vector angles computed from force-balance measurements are presented.

Flow reversal power limit for the HFBR

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

Cheng, Lap Y.; Tichler, P.R.

The High Flux Beam Reactor (HFBR) undergoes a buoyancy-driven reversal of flow in the reactor core following certain postulated accidents. Uncertainties about the afterheat removal capability during the flow reversal has limited the reactor operating power to 30 MW. An experimental and analytical program to address these uncertainties is described in this report. The experiments were single channel flow reversal tests under a range of conditions. The analytical phase involved simulations of the tests to benchmark the physical models and development of a criterion for dryout. The criterion is then used in simulations of reactor accidents to determine a safemore » operating power level. It is concluded that the limit on the HFBR operating power with respect to the issue of flow reversal is in excess of 60 MW.« less

Over-the-wing model thrust reverser noise tests

NASA Technical Reports Server (NTRS)

Goodykoontz, J.; Gutierrez, O.

1977-01-01

Static acoustic tests were conducted on a 1/12 scale model over-the-wing target type thrust reverser. The model configuration simulates a design that is applicable to the over-the-wing short-haul advanced technology engine. Aerodynamic screening tests of a variety of reverser designs identified configurations that satisfied a reverse thrust requirement of 35 percent of forward thrust at a nozzle pressure ratio of 1.29. The variations in the reverser configuration included, blocker door angle, blocker door lip angle and shape, and side skirt shape. Acoustic data are presented and compared for the various configurations. The model data scaled to a single full size engine show that peak free field perceived noise (PN) levels at a 152.4 meter sideline distance range from 98 to 104 PNdb.

Electric-field-driven magnetization reversal in square-shaped nanomagnet-based multiferroic heterostructure

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

Peng, Ren-Ci; Nan, Ce-Wen, E-mail: jzw12@psu.edu, E-mail: cwnan@tsinghua.edu.cn; Wang, J. J., E-mail: jzw12@psu.edu, E-mail: cwnan@tsinghua.edu.cn

Based on phase field modeling and thermodynamic analysis, purely electric-field-driven magnetization reversal was shown to be possible in a multiferroic heterostructure of a square-shaped amorphous Co{sub 40}Fe{sub 40}B{sub 20} nanomagnet on top of a ferroelectric layer through electrostrain. The reversal is made possible by engineering the mutual interactions among the built-in uniaxial magnetic anisotropy, the geometry-dependent magnetic configuration anisotropy, and the magnetoelastic anisotropy. Particularly, the incorporation of the built-in uniaxial anisotropy made it possible to reverse magnetization with one single unipolar electrostrain pulse, which is simpler than previous designs involving the use of bipolar electrostrains and may alleviate ferroelectric fatigue.more » Critical conditions for triggering the magnetization reversal are identified.« less

Controlled method of reducing electrophoretic mobility of macromolecules, particles, or cells

NASA Technical Reports Server (NTRS)

Vanalstine, James M. (Inventor)

1992-01-01

A method of reducing electrophoretic mobility of macromolecules, particles, cells, and other substances is provided which comprises interacting in a conventional electrophoretic separating procedure, the substances with a polymer-linked affinity compound comprised of a hydrophilic neutral polymer such as polyethylene glycol bound to a second component such as a hydrophobic compound, an immunocompound such as an antibody or antibody active fragment, or a ligand such as a hormone, drug, antigen, or a hapten. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and such reduction can comprise up to 100 percent for particular particles and cells. The present invention is advantageous in that electrophoretic separation can now be achieved for substances whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of the specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions.

Reversible Regulation of Catalytic Activity of Gold Nanoparticles with DNA Nanomachines

NASA Astrophysics Data System (ADS)

Zhou, Peipei; Jia, Sisi; Pan, Dun; Wang, Lihua; Gao, Jimin; Lu, Jianxin; Shi, Jiye; Tang, Zisheng; Liu, Huajie

2015-09-01

Reversible catalysis regulation has gained much attention and traditional strategies utilized reversible ligand coordination for switching catalyst’s conformations. However, it remains challenging to regulate the catalytic activity of metal nanoparticle-based catalysts. Herein, we report a new DNA nanomachine-driven reversible nano-shield strategy for circumventing this problem. The basic idea is based on the fact that the conformational change of surface-attached DNA nanomachines will cause the variation of the exposed surface active area on metal nanoparticles. As a proof-of-concept study, we immobilized G-rich DNA strands on gold nanoparticles (AuNPs) which have glucose oxidase (GOx) like activity. Through the reversible conformational change of the G-rich DNA between a flexible single-stranded form and a compact G-quadruplex form, the catalytic activity of AuNPs has been regulated reversibly for several cycles. This strategy is reliable and robust, which demonstrated the possibility of reversibly adjusting catalytic activity with external surface coverage switching, rather than coordination interactions.

Thermal gradients for the stabilization of a single domain wall in magnetic nanowires.

PubMed

Mejía-López, J; Velásquez, E A; Mazo-Zuluaga, J; Altbir, D

2018-08-24

By means of Monte Carlo simulations we studied field driven nucleation and propagation of transverse domain walls (DWs) in magnetic nanowires subjected to temperature gradients. Simulations identified the existence of critical thermal gradients that allow the existence of reversal processes driven by a single DW. Critical thermal gradients depend on external parameters such as temperature, magnetic field and wire length, and can be experimentally obtained through the measurement of the mean velocity of the magnetization reversal as a function of the temperature gradient. Our results show that temperature gradients provide a high degree of control over DW propagation, which is of great importance for technological applications.

He Did What?: The role of diagnosticity in revising implicit evaluations

PubMed Central

Cone, Jeremy; Ferguson, Melissa J.

2015-01-01

Research suggests that implicit evaluations are relatively insensitive to single instances of new, countervailing information that contradicts prior learning. In six experiments, however, we identify the critical role of the perceived diagnosticity of that new information: counter-attitudinal information that is deemed highly diagnostic of the target's true nature leads to a complete reversal of the previous implicit evaluation. Experiments 1a and 1b establish this effect by showing that newly-formed implicit evaluations are reversed minutes later with exposure to a single piece of highly diagnostic information. Experiment 2 demonstrates a valence asymmetry in participants’ likelihood of exhibiting rapid reversals of newly formed positive versus negative implicit evaluations. Experiment 3 provides evidence that a target must be personally responsible for the counter-attitudinal behavior and not merely incidentally associated with a negative act. Experiment 4 shows that participants exhibit revision only when they judge the target's counter-attitudinal behavior as offensive and thus diagnostic of his character. Experiment 5 demonstrates the behavioral implications of newly-revised implicit evaluations. These studies show that newly-formed implicit evaluations can be completely overturned through deliberative considerations about a single piece of counter-attitudinal information. PMID:25365037

Glycosaminoglycan blotting on nitrocellulose membranes treated with cetylpyridinium chloride after agarose-gel electrophoretic separation.

PubMed

Maccari, Francesca; Volpi, Nicola

2002-09-01

We describe a method for blotting and immobilizing several nonsulfated and sulfated complex polysaccharides on membranes made hydrophilic and positively charged by a cationic detergent after their separation by conventional agarose gel electrophoresis. Nitrocellulose membranes were derivatized with the cationic detergent cetylpyridinium chloride (CPC) and mixtures of glycosaminoglycans (GAGs) were capillary-blotted after their separation in agarose gel electrophoresis in barium acetate/1,2-diaminopropane. Single purified species of variously sulfated polysaccharides were transferred onto the derivatized membranes after electrophoresis with an efficiency of 100% and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining) permitting about 0.1 nug threshold of detection. Nonsulfated polyanions, hyaluronic acid, a fructose-containing polysaccharide with a chondroitin backbone purified from Escherichia coli U1-41, and its defructosylated product, were also electrophoretically separated and transferred onto membranes. The limit of detection for desulfated GAGs was about 0.1-0.5 nug after irreversible or reversible staining. GAG extracts from bovine, lung and aorta, and human aorta and urine were separated by agarose gel electrophoresis and blotted on CPC-treated nitrocellulose membranes. The polysaccharide composition of these extracts was determined. The membrane stained with toluidine blue (reversible staining) was destained and the same lanes used for immunological detection or other applications. Reversible staining was also applied to recover single species of polysaccharides after electrophoretic separation of mixtures of GAGs and their transfer onto membranes. Single bands were released from the membrane with an efficiency of 70-100% for further biochemical characterization.

Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy.

PubMed

Chen, Jiahuan; Ganguly, Anutosh; Mucsi, Ashley D; Meng, Junchen; Yan, Jiacong; Detampel, Pascal; Munro, Fay; Zhang, Zongde; Wu, Mei; Hari, Aswin; Stenner, Melanie D; Zheng, Wencheng; Kubes, Paul; Xia, Tie; Amrein, Matthias W; Qi, Hai; Shi, Yan

2017-02-01

Dendritic cells are targeted by regulatory T (T reg) cells, in a manner that operates as an indirect mode of T cell suppression. In this study, using a combination of single-cell force spectroscopy and structured illumination microscopy, we analyze individual T reg cell-DC interaction events and show that T reg cells exhibit strong intrinsic adhesiveness to DCs. This increased DC adhesion reduces the ability of contacted DCs to engage other antigen-specific cells. We show that this unusually strong LFA-1-dependent adhesiveness of T reg cells is caused in part by their low calpain activities, which normally release integrin-cytoskeleton linkage, and thereby reduce adhesion. Super resolution imaging reveals that such T reg cell adhesion causes sequestration of Fascin-1, an actin-bundling protein essential for immunological synapse formation, and skews Fascin-1-dependent actin polarization in DCs toward the T reg cell adhesion zone. Although it is reversible upon T reg cell disengagement, this sequestration of essential cytoskeletal components causes a lethargic state of DCs, leading to reduced T cell priming. Our results reveal a dynamic cytoskeletal component underlying T reg cell-mediated DC suppression in a contact-dependent manner. © 2017 Chen et al.

Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy

PubMed Central

Mucsi, Ashley D.; Meng, Junchen; Yan, Jiacong; Zhang, Zongde; Wu, Mei; Hari, Aswin; Stenner, Melanie D.; Zheng, Wencheng; Kubes, Paul; Xia, Tie; Amrein, Matthias W.

2017-01-01

Dendritic cells are targeted by regulatory T (T reg) cells, in a manner that operates as an indirect mode of T cell suppression. In this study, using a combination of single-cell force spectroscopy and structured illumination microscopy, we analyze individual T reg cell–DC interaction events and show that T reg cells exhibit strong intrinsic adhesiveness to DCs. This increased DC adhesion reduces the ability of contacted DCs to engage other antigen-specific cells. We show that this unusually strong LFA-1–dependent adhesiveness of T reg cells is caused in part by their low calpain activities, which normally release integrin–cytoskeleton linkage, and thereby reduce adhesion. Super resolution imaging reveals that such T reg cell adhesion causes sequestration of Fascin-1, an actin-bundling protein essential for immunological synapse formation, and skews Fascin-1–dependent actin polarization in DCs toward the T reg cell adhesion zone. Although it is reversible upon T reg cell disengagement, this sequestration of essential cytoskeletal components causes a lethargic state of DCs, leading to reduced T cell priming. Our results reveal a dynamic cytoskeletal component underlying T reg cell–mediated DC suppression in a contact-dependent manner. PMID:28082358

Contact discontinuities in a cold collision-free two-beam plasma

NASA Technical Reports Server (NTRS)

Kirkland, K. B.; Sonnerup, B. U. O.

1982-01-01

The structure of contact discontinuities in a collision-free plasma is examined using a model of a plasma which consists of two oppositely directed cold ion beams and a background of cold massless electrons such that exact charge neutrality is maintained and that the electric field is zero. The basic equations describing self-consistent equilibria are obtained for the more general situation where a net flow across the layer takes place and where the magnetic field has two nonzero tangential components but where the electric field remains zero. These equations are then specialized to the case of no net plasma flow where one of the tangential components is zero, and four different classes of sheets are obtained, all having thickness the order of the ion inertial length. The first class is for layers separating two identical plasma and magnetic field regions, the second is for an infinite array of parallel layers producing an undulated magnetic field, the third is for layers containing trapped ions in closed orbits which separate two vacuum regions with uniform identical magnetic fields, and the fourth is for layers which reflect a single plasma beam, leaving a vacuum with a reversed and compressed tangential field on the other side.

Electromagnetic coupling of spins and pseudospins in bilayer graphene

NASA Astrophysics Data System (ADS)

Winkler, R.; Zülicke, U.

2015-03-01

We present a theoretical study of bilayer-graphene's electronic properties in the presence of electric and magnetic fields. In contrast to known materials, including single-layer graphene, any possible coupling of physical quantities to components of the electric field has a counterpart where the analogous component of the magnetic field couples to exactly the same quantities. For example, a purely electric spin splitting appears as the magneto-electric analogue of the magnetic Zeeman spin splitting. The measurable thermodynamic response induced by magnetic and electric fields is thus completely symmetric. The Pauli magnetization induced by a magnetic field takes exactly the same functional form as the polarization induced by an electric field. Although they seem counterintuitive, our findings are consistent with fundamental principles such as time reversal symmetry. For example, only a magnetic field can give rise to a macroscopic spin polarization, whereas only a perpendicular electric field can induce a macroscopic polarization of the sublattice-related pseudospin in bilayer graphene. These rules enforced by symmetry for the matter-field interactions clarify the nature of spins versus pseudospins. We have obtained numerical values of prefactors for relevant terms. NSF Grant DMR-1310199 and Marsden Fund Contract No. VUW0719.

Reliability Assessment of GaN Power Switches

DTIC Science & Technology

2015-04-17

Possibilities for single event burnout testing were examined as well. Device simulation under the conditions of some of the testing was performed on...reverse-bias (HTRB) and single electron burnout (SEE) tests. 8. Refine test structures, circuits, and procedures, and, if possible, develop

Finding a Single Molecule in a Haystack: Optical Detection and Spectroscopy of Single Absorbers in Solids

DTIC Science & Technology

1989-08-18

CODES 18 SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP Single Molecule Detection Pentacene in p...and 10 additional pentacene molecules. This may be accomplished by- a combination of laser FM spectroscopy and either Stark or ultrasonic double...6099 408-927-2426 ABSTRACT: Single-absorber optical spectroscopy in solids is described for the case of finding a single pentacene molecule in a

Simultaneous analysis of 11 main active components in Cirsium setosum based on HPLC-ESI-MS/MS and combined with statistical methods.

PubMed

Sun, Qian; Chang, Lu; Ren, Yanping; Cao, Liang; Sun, Yingguang; Du, Yingfeng; Shi, Xiaowei; Wang, Qiao; Zhang, Lantong

2012-11-01

A novel method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry was developed for simultaneous determination of the 11 major active components including ten flavonoids and one phenolic acid in Cirsium setosum. Separation was performed on a reversed-phase C(18) column with gradient elution of methanol and 0.1‰ acetic acid (v/v). The identification and quantification of the analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple-reaction monitoring scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. Full validation of the assay was carried out including linearity, precision, accuracy, stability, limits of detection and quantification. The results demonstrated that the method developed was reliable, rapid, and specific. The 25 batches of C. setosum samples from different sources were first determined using the developed method and the total contents of 11 analytes ranged from 1717.460 to 23028.258 μg/g. Among them, the content of linarin was highest, and its mean value was 7340.967 μg/g. Principal component analysis and hierarchical clustering analysis were performed to differentiate and classify the samples, which is helpful for comprehensive evaluation of the quality of C. setosum. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantitative Trait Loci Mapping in Brassica rapa Revealed the Structural and Functional Conservation of Genetic Loci Governing Morphological and Yield Component Traits in the A, B, and C Subgenomes of Brassica Species

PubMed Central

Li, Xiaonan; Ramchiary, Nirala; Dhandapani, Vignesh; Choi, Su Ryun; Hur, Yoonkang; Nou, Ill-Sup; Yoon, Moo Kyoung; Lim, Yong Pyo

2013-01-01

Brassica rapa is an important crop species that produces vegetables, oilseed, and fodder. Although many studies reported quantitative trait loci (QTL) mapping, the genes governing most of its economically important traits are still unknown. In this study, we report QTL mapping for morphological and yield component traits in B. rapa and comparative map alignment between B. rapa, B. napus, B. juncea, and Arabidopsis thaliana to identify candidate genes and conserved QTL blocks between them. A total of 95 QTL were identified in different crucifer blocks of the B. rapa genome. Through synteny analysis with A. thaliana, B. rapa candidate genes and intronic and exonic single nucleotide polymorphisms in the parental lines were detected from whole genome resequenced data, a few of which were validated by mapping them to the QTL regions. Semi-quantitative reverse transcriptase PCR analysis showed differences in the expression levels of a few genes in parental lines. Comparative mapping identified five key major evolutionarily conserved crucifer blocks (R, J, F, E, and W) harbouring QTL for morphological and yield components traits between the A, B, and C subgenomes of B. rapa, B. juncea, and B. napus. The information of the identified candidate genes could be used for breeding B. rapa and other related Brassica species. PMID:23223793

Massively parallel single-molecule and single-cell emulsion reverse transcription polymerase chain reaction using agarose droplet microfluidics.

PubMed

Zhang, Huifa; Jenkins, Gareth; Zou, Yuan; Zhu, Zhi; Yang, Chaoyong James

2012-04-17

A microfluidic device for performing single copy, emulsion Reverse Transcription Polymerase Chain Reaction (RT-PCR) within agarose droplets is presented. A two-aqueous-inlet emulsion droplet generator was designed and fabricated to produce highly uniform monodisperse picoliter agarose emulsion droplets with RT-PCR reagents in carrier oil. Template RNA or cells were delivered from one inlet with RT-PCR reagents/cell lysis buffer delivered separately from the other. Efficient RNA/cell encapsulation and RT-PCR at the single copy level was achieved in agarose-in-oil droplets, which, after amplification, can be solidified into agarose beads for further analysis. A simple and efficient method to graft primer to the polymer matrix using 5'-acrydite primer was developed to ensure highly efficient trapping of RT-PCR products in agarose. High-throughput single RNA molecule/cell RT-PCR was demonstrated in stochastically diluted solutions. Our results indicate that single-molecule RT-PCR can be efficiently carried out in agarose matrix. Single-cell RT-PCR was successfully performed which showed a clear difference in gene expression level of EpCAM, a cancer biomarker gene, at the single-cell level between different types of cancer cells. This work clearly demonstrates for the first time, single-copy RT-PCR in agarose droplets. We believe this will open up new possibilities for viral RNA detection and single-cell transcription analysis.

REVERSE SIGNALING BY GPI-LINKED MANDUCA EPHRIN REQUIRES A SRC FAMILY KINASE TO RESTRICT NEURONAL MIGRATION IN VIVO

PubMed Central

Coate, Thomas M.; Swanson, Tracy L.; Copenhaver, Philip F.

2011-01-01

Reverse signaling via GPI-linked Ephrins may help control cell proliferation and outgrowth within the nervous system, but the mechanisms underlying this process remain poorly understood. In the embryonic enteric nervous system (ENS) of the moth Manduca sexta, migratory neurons forming the enteric plexus (EP cells) express a single Ephrin ligand (GPI-linked MsEphrin), while adjacent midline cells that are inhibitory to migration express the cognate receptor (MsEph). Knocking down MsEph receptor expression in cultured embryos with antisense morpholino oligonucleotides allowed the EP cells to cross the midline inappropriately, consistent with the model that reverse signaling via MsEphrin mediates a repulsive response in the ENS. Src family kinases have been implicated in reverse signaling by type-A Ephrins in other contexts, and MsEphrin colocalizes with activated forms of endogenous Src in the leading processes of the EP cells. Pharmacological inhibition of Src within the developing ENS induced aberrant midline crossovers, similar to the effect of blocking MsEphrin reverse signaling. Hyperstimulating MsEphrin reverse signaling with MsEph-Fc fusion proteins induced the rapid activation of endogenous Src specifically within the EP cells, as assayed by Western blots of single embryonic gut explants and by whole-mount immunostaining of cultured embryos. In longer cultures, treatment with MsEph-Fc caused a global inhibition of EP cell migration and outgrowth, an effect that was prevented by inhibiting Src activation. These results support the model that MsEphrin reverse signaling induces the Src-dependent retraction of EP cell processes away from the enteric midline, thereby helping to confine the neurons to their appropriate pathways. PMID:19295147

Wavefront reversal technique for self-referencing collimation testing

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

Hii, King Ung; Kwek, Kuan Hiang

2010-02-01

We present a wavefront reversal technique to produce a dual-field fringe pattern for self-referencing collimation testing in wedge-plate lateral-shear interferometry. The method requires only a suitably placed cubic beam splitter to produce two replicas of the fringe field formed by the wedge-plate lateral-shear interferometer. One of the replicas has a fringe pattern that is the reverse of the other. With these two fringe fields, the collimation testing has a built-in reference, and the detection sensitivity is twice that of a single-wedge-plate technique.

Bottom-up and Top-down Input Augment the Variability of Cortical Neurons

PubMed Central

Nassi, Jonathan J.; Kreiman, Gabriel; Born, Richard T.

2016-01-01

SUMMARY Neurons in the cerebral cortex respond inconsistently to a repeated sensory stimulus, yet they underlie our stable sensory experiences. Although the nature of this variability is unknown, its ubiquity has encouraged the general view that each cell produces random spike patterns that noisily represent its response rate. In contrast, here we show that reversibly inactivating distant sources of either bottom-up or top-down input to cortical visual areas in the alert primate reduces both the spike train irregularity and the trial-to-trial variability of single neurons. A simple model in which a fraction of the pre-synaptic input is silenced can reproduce this reduction in variability, provided that there exist temporal correlations primarily within, but not between, excitatory and inhibitory input pools. A large component of the variability of cortical neurons may therefore arise from synchronous input produced by signals arriving from multiple sources. PMID:27427459

Internal strain drives spontaneous periodic buckling in collagen and regulates remodeling.

PubMed

Dittmore, Andrew; Silver, Jonathan; Sarkar, Susanta K; Marmer, Barry; Goldberg, Gregory I; Neuman, Keir C

2016-07-26

Fibrillar collagen, an essential structural component of the extracellular matrix, is remarkably resistant to proteolysis, requiring specialized matrix metalloproteinases (MMPs) to initiate its remodeling. In the context of native fibrils, remodeling is poorly understood; MMPs have limited access to cleavage sites and are inhibited by tension on the fibril. Here, single-molecule recordings of fluorescently labeled MMPs reveal cleavage-vulnerable binding regions arrayed periodically at ∼1-µm intervals along collagen fibrils. Binding regions remain periodic even as they migrate on the fibril, indicating a collective process of thermally activated and self-healing defect formation. An internal strain relief model involving reversible structural rearrangements quantitatively reproduces the observed spatial patterning and fluctuations of defects and provides a mechanism for tension-dependent stabilization of fibrillar collagen. This work identifies internal-strain-driven defects that may have general and widespread regulatory functions in self-assembled biological filaments.

Utilizing zero-sequence switchings for reversible converters

DOEpatents

Hsu, John S.; Su, Gui-Jia; Adams, Donald J.; Nagashima, James M.; Stancu, Constantin; Carlson, Douglas S.; Smith, Gregory S.

2004-12-14

A method for providing additional dc inputs or outputs (49, 59) from a dc-to-ac inverter (10) for controlling motor loads (60) comprises deriving zero-sequence components (V.sub.ao, V.sub.bo, and V.sub.co) from the inverter (10) through additional circuit branches with power switching devices (23, 44, 46), transforming the voltage between a high voltage and a low voltage using a transformer or motor (42, 50), converting the low voltage between ac and dc using a rectifier (41, 51) or an H-bridge (61), and providing at least one low voltage dc input or output (49, 59). The transformation of the ac voltage may be either single phase or three phase. Where less than a 100% duty cycle is acceptable, a two-phase modulation of the switching signals controlling the inverter (10) reduces switching losses in the inverter (10). A plurality of circuits for carrying out the invention are also disclosed.

DC breakdown characteristics of silicone polymer composites for HVDC insulator applications

NASA Astrophysics Data System (ADS)

Han, Byung-Jo; Seo, In-Jin; Seong, Jae-Kyu; Hwang, Young-Ho; Yang, Hai-Won

2015-11-01

Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.

Thermodynamic characterization of hydrogen interaction with iridium polyhydride complexes

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

Zidan, R.A.; Rocheleau, R.E.

1999-01-01

Hydrogen interaction with solid iridium complexes IrXH{sub 2}(PPr3{sup i}){sub 2} (X=Cl, I) was investigated. Gaseous hydrogen was found to react reversibly with solid chloro-iridium complex IrClH{sub 2}(PPr3{sup i}){sub 2} forming IrClH{sub 2}(PPr3{sup i}){sub 2}H{sub 2}. The relative partial molal enthalpy and entropy were obtained from equilibrium isotherms at different hydrogen concentrations. The decrease in entropy with increasing hydrogen concentration and the absence of plateaus in the equilibrium isotherms were consistent with a single phase solid solution with two chemical components. Hydrogen release from solid iodo-iridium complex IrIH{sub 2}(PPr3{sup i}){sub 2}H{sub 2} was not observed at temperatures up to 350 K,more » indicating stronger hydrogen bonding. {copyright} {ital 1999 Materials Research Society.}« less

Evidence for rapid uptake of D-galacturonic acid in the yeast Saccharomyces cerevisiae by a channel-type transport system.

PubMed

Souffriau, Ben; den Abt, Tom; Thevelein, Johan M

2012-07-30

D-Galacturonic acid is a major component of pectins but cannot be metabolized by Saccharomyces cerevisiae. It is assumed not to be taken up. We show that yeast displays surprisingly rapid low-affinity uptake of D-galacturonic acid, strongly increasing with decreasing extracellular pH and without saturation up to 1.5 M. There was no intracellular concentration above the extracellular level and transport was reversible. Among more than 160 single and multiple deletion mutants in channels and transporters, no strain was affected in D-galacturonic acid uptake. The uptake was not inhibited by any compound tested as candidate competitive inhibitor, including D-glucuronic acid, which was also transported. The characteristics of D-galacturonic acid uptake are consistent with involvement of a channel-type system, probably encoded by multiple genes. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

THEMIS, a new T cell specific protein important for late thymocyte development

PubMed Central

Lesourne, Renaud; Uehara, Shoji; Lee, Jan; Song, Ki-Duk; Li, LiQi; Pinkhasov, Julia; Zhang, Yongqing; Weng, Nan-Ping; Wildt, Kathryn F.; Wang, Lie; Bosselut, Remy; Love, Paul E.

2010-01-01

During positive selection, thymocytes transition through a stage during which T cell receptor (TCR) signaling controls CD4 versus CD8 lineage choice and subsequent maturation. Here, we describe a new T cell specific protein, THEMIS, that performs a distinct function during this stage. In Themis-/- mice, thymocyte selection was impaired and the number of transitional CD4+CD8int thymocytes as well as CD4 and CD8 single positive thymocytes was decreased. Remarkably, although no overt TCR-proximal signaling deficiencies were detected, Themis-/-CD4+CD8int thymocytes exhibited developmental defects consistent with attenuated signaling that were reversible by increased TCR stimulation. These results identify THEMIS as a critical component of the T cell developmental program and suggest that THEMIS functions to sustain and/or integrate signals required for proper lineage commitment and maturation. PMID:19597498

A model of the thermal-spike mechanism in graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Adamson, M. J.

1982-01-01

The influence of a thermal spike on a moisture-saturated graphite/epoxy composite was studied in detail. A single thermal spike from 25 C to 132 C was found to produce damage as evidenced by a significant increase in the level of moisture saturation in the composite. Approximately half of this increase remained after a vacuum anneal at 150 C for 7 days, suggesting the presence of an irreversible damage component. Subsequent thermal spikes created less and less additional moisture absorption, with the cumulative effect being a maximum or limiting moisture capacity of the composite. These observations are explained in terms of a model previously developed to explain the reverse thermal effect of moisture absorption in epoxy and epoxy matrix composites. This model, based on the inverse temperature dependence of free volume, contributes an improved understanding of thermal-spike effects in graphite/epoxy composites.

High Storage Efficiency and Large Fractional Delay of EIT-Based Memory

NASA Astrophysics Data System (ADS)

Chen, Yi-Hsin; Lee, Meng-Jung; Wang, I.-Chung; Du, Shengwang; Chen, Yong-Fan; Chen, Ying-Cheng; Yu, Ite

2013-05-01

In long-distance quantum communication and optical quantum computation, an efficient and long-lived quantum memory is an important component. We first experimentally demonstrated that a time-space-reversing method plus the optimum pulse shape can improve the storage efficiency (SE) of light pulses to 78% in cold media based on the effect of electromagnetically induced transparency (EIT). We obtain a large fractional delay of 74 at 50% SE, which is the best record so far. The measured classical fidelity of the recalled pulse is higher than 90% and nearly independent of the storage time, implying that the optical memory maintains excellent phase coherence. Our results suggest the current result may be readily applied to single-photon quantum states due to quantum nature of the EIT light-matter inference. This study advances the EIT-based quantum memory in practical quantum information applications.

Internal strain drives spontaneous periodic buckling in collagen and regulates remodeling

PubMed Central

Dittmore, Andrew; Silver, Jonathan; Sarkar, Susanta K.; Marmer, Barry; Goldberg, Gregory I.; Neuman, Keir C.

2016-01-01

Fibrillar collagen, an essential structural component of the extracellular matrix, is remarkably resistant to proteolysis, requiring specialized matrix metalloproteinases (MMPs) to initiate its remodeling. In the context of native fibrils, remodeling is poorly understood; MMPs have limited access to cleavage sites and are inhibited by tension on the fibril. Here, single-molecule recordings of fluorescently labeled MMPs reveal cleavage-vulnerable binding regions arrayed periodically at ∼1-µm intervals along collagen fibrils. Binding regions remain periodic even as they migrate on the fibril, indicating a collective process of thermally activated and self-healing defect formation. An internal strain relief model involving reversible structural rearrangements quantitatively reproduces the observed spatial patterning and fluctuations of defects and provides a mechanism for tension-dependent stabilization of fibrillar collagen. This work identifies internal–strain-driven defects that may have general and widespread regulatory functions in self-assembled biological filaments. PMID:27402741

Scandium(III) catalysis of transimination reactions. Independent and constitutionally coupled reversible processes.

PubMed

Giuseppone, Nicolas; Schmitt, Jean-Louis; Schwartz, Evan; Lehn, Jean-Marie

2005-04-20

Sc(OTf)(3) efficiently catalyzes the self-sufficient transimination reaction between various types of C=N bonds in organic solvents, with turnover frequencies up to 3600 h(-)(1) and rate accelerations up to 6 x 10(5). The mechanism of the crossover reaction in mixtures of amines and imines is studied, comparing parallel individual reactions with coupled equilibria. The intrinsic kinetic parameters for isolated reactions cannot simply be added up when several components are mixed, and the behavior of the system agrees with the presence of a unique mediator that constitutes the core of a network of competing reactions. In mixed systems, every single amine or imine competes for the same central hub, in accordance with their binding affinity for the catalyst metal ion center. More generally, the study extends the basic principles of constitutional dynamic chemistry to interconnected chemical transformations and provides a step toward dynamic systems of increasing complexity.

Crystalline Microporous Organosilicates with Reversed Functionalities of Organic and Inorganic Components for Room-Temperature Gas Sensing.

PubMed

Fabbri, Barbara; Bonoldi, Lucia; Guidi, Vincenzo; Cruciani, Giuseppe; Casotti, Davide; Malagù, Cesare; Bellussi, Giuseppe; Millini, Roberto; Montanari, Luciano; Carati, Angela; Rizzo, Caterina; Montanari, Erica; Zanardi, Stefano

2017-07-26

A deepened investigation on an innovative organic-inorganic hybrid material, referred to as ECS-14 (where ECS = Eni carbon silicates), revealed the possibility to use them as gas sensors. Indeed, among ECS phases, the crystalline state and the hexagonal microplateletlike morphology characteristic of ECS-14 seemed favorable properties to obtain continuous and uniform films. ECS-14 phase was used as functional material in screen-printable compositions and was thus deposited by drop coating for morphological, structural, thermal, and electrical characterizations. Possible operation at room temperature was investigated as technological progress, offering intrinsic safety in sensors working in harsh or industrial environments and avoiding high power consumption of most common sensors based on metal oxide semiconductors. Electrical characterization of the sensors based on ECS-14 versus concentrations of gaseous analytes gave significant results at room temperature in the presence of humidity, thereby demonstrating fundamental properties for a good quality sensor (speed, reversibility, and selectivity) that make them competitive with respect to systems currently in use. Remarkably, we observed functionality reversal of the organic and inorganic components; that is, in contrast to other hybrids, for ECS-14 the functional site has been ascribed to the inorganic phase while the organic component provided structural stability to the material. The sensing mechanism for humidity was also investigated.

Reversible Redox Activity by Ion-pH Dually Modulated Duplex Formation of i-Motif DNA with Complementary G-DNA.

PubMed

Chang, Soyoung; Kilic, Tugba; Lee, Chang Kee; Avci, Huseyin; Bae, Hojae; Oskui, Shirin Mesbah; Jung, Sung Mi; Shin, Su Ryon; Kim, Seon Jeong

2018-04-08

The unique biological features of supramolecular DNA have led to an increasing interest in biomedical applications such as biosensors. We have developed an i-motif and G-rich DNA conjugated single-walled carbon nanotube hybrid materials, which shows reversible conformational switching upon external stimuli such as pH (5 and 8) and presence of ions (Li⁺ and K⁺). We observed reversible electrochemical redox activity upon external stimuli in a quick and robust manner. Given the ease and the robustness of this method, we believe that pH- and ion-driven reversible DNA structure transformations will be utilized for future applications for developing novel biosensors.

[Metachronous Bilateral Hemothorax Due to Reverse Chance Type Thoracic Fracture].

PubMed

Fukada, Takehisa; Morita, Katsuhiko; Ueki, Takayuki; Hanaoka, Nobuharu

2017-06-01

Metachronous bilateral hemothorax due to reverse Chance type thoracic fracture is very rare. In this case, we experienced a case of metachronous bilateral hemothorax, triggered by a thoracic fracture in which the anterior component of the spine collapsed, so-called reverse Chance type thoracic fracture. An 83-year-old woman with spinal kyphosis traumatically injured thoracic spine burst fracture, and bone fragments appeared on both sides of the destroyed vertebra. After injury, the left hemothorax also appeared, followed by the right hemothorax causing hemorrhagic shock. In thoracic destructive anterior fracture, we should consider the possibility of metachronous bilateral hemothorax.

Low-temperature magnetic properties of greigite (Fe3S4)

NASA Astrophysics Data System (ADS)

Chang, Liao; Roberts, Andrew P.; Rowan, Christopher J.; Tang, Yan; Pruner, Petr; Chen, Qianwang; Horng, Chorng-Shern

2009-01-01

We provide comprehensive low-temperature magnetic results for greigite (Fe3S4) across the spectrum from superparamagnetic (SP) to multidomain (MD) behavior. It is well known that greigite has no low-temperature magnetic transitions, but we also document that it has strong domain-state dependence of magnetic properties at low temperatures. Blocking of SP grains and increasing thermal stability with decreasing temperature is apparent in many magnetic measurements. Thermally stable single-domain greigite undergoes little change in magnetic properties below room temperature. For pseudo-single-domain (PSD)/MD greigite, hysteresis properties and first-order reversal curve diagrams exhibit minor changes at low temperatures, while remanence continuously demagnetizes because of progressive domain wall unpinning. The low-temperature demagnetization is grain size dependent for PSD/MD greigite, with coarser grains undergoing larger remanence loss. AC susceptibility measurements indicate consistent blocking temperatures (TB) for all synthetic and natural greigite samples, which are probably associated with surficial oxidation. Low-temperature magnetic analysis provides much more information about magnetic mineralogy and domain state than room temperature measurements and enables discrimination of individual components within mixed magnetic mineral assemblages. Low-temperature rock magnetometry is therefore a useful tool for studying magnetic mineralogy and granulometry of greigite-bearing sediments.

Simultaneous Quantification of Multiple Alternatively Spliced mRNA Transcripts Using Droplet Digital PCR.

PubMed

Sun, Bing; Zheng, Yun-Ling

2018-01-01

Currently there is no sensitive, precise, and reproducible method to quantitate alternative splicing of mRNA transcripts. Droplet digital™ PCR (ddPCR™) analysis allows for accurate digital counting for quantification of gene expression. Human telomerase reverse transcriptase (hTERT) is one of the essential components required for telomerase activity and for the maintenance of telomeres. Several alternatively spliced forms of hTERT mRNA in human primary and tumor cells have been reported in the literature. Using one pair of primers and two probes for hTERT, four alternatively spliced forms of hTERT (α-/β+, α+/β- single deletions, α-/β- double deletion, and nondeletion α+/β+) were accurately quantified through a novel analysis method via data collected from a single ddPCR reaction. In this chapter, we describe this ddPCR method that enables direct quantitative comparison of four alternatively spliced forms of the hTERT messenger RNA without the need for internal standards or multiple pairs of primers specific for each variant, eliminating the technical variation due to differential PCR amplification efficiency for different amplicons and the challenges of quantification using standard curves. This simple and straightforward method should have general utility for quantifying alternatively spliced gene transcripts.

Orthogonality Catastrophe as a prerequisite for the irreversible decay of the global relative phase of a two-component Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Birman, Joseph L.; Kuklov, A. B.

2001-05-01

The concept of the orthogonality catastrophe (OC), which has been introduced previously for one component condensate ( A.B. Kuklov, J.L. Birman, PRA 63), 013609 (2001), is applied to the two-component condensate. The evolution of the global relative phase, which is created by the rf-pulse, is studied under the condition of no exchange of bosons between the components after the pulse. It is shown that the normal component does not induce the OC. Instead, it produces a reversible thermal dephasing, which competes with the quantum phase diffusion (QPD) effect (E.M.Wright, et al, PRL 77), 2158(1996). The thermal dephasing results from the thermal ensemble averaging, and the corresponding dephasing rate is controlled by the two-body interaction and temperature as well as by the closeness to the intrinsic su(2) symmetry, so that no dephasing exists in the case of the exact symmetry (A.B. Kuklov, J.L. Birman, PRL 85), 5488 (2000). The reversible nature of the thermal dephasing as well as of the QPD can be revealed in the atomic echo effect. The role of external noise in erasing the phase memory is discussed as well.

Quantifying irreversible movement in steep, fractured bedrock permafrost on Matterhorn (CH)

NASA Astrophysics Data System (ADS)

Weber, Samuel; Beutel, Jan; Faillettaz, Jérome; Hasler, Andreas; Krautblatter, Michael; Vieli, Andreas

2017-02-01

Understanding rock slope kinematics in steep, fractured bedrock permafrost is a challenging task. Recent laboratory studies have provided enhanced understanding of rock fatigue and fracturing in cold environments but were not successfully confirmed by field studies. This study presents a unique time series of fracture kinematics, rock temperatures and environmental conditions at 3500 m a. s. l. on the steep, strongly fractured Hörnligrat of the Matterhorn (Swiss Alps). Thanks to 8 years of continuous data, the longer-term evolution of fracture kinematics in permafrost can be analyzed with an unprecedented level of detail. Evidence for common trends in spatiotemporal pattern of fracture kinematics could be found: a partly reversible seasonal movement can be observed at all locations, with variable amplitudes. In the wider context of rock slope stability assessment, we propose separating reversible (elastic) components of fracture kinematics, caused by thermoelastic strains, from the irreversible (plastic) component due to other processes. A regression analysis between temperature and fracture displacement shows that all instrumented fractures exhibit reversible displacements that dominate fracture kinematics in winter. Furthermore, removing this reversible component from the observed displacement enables us to quantify the irreversible component. From this, a new metric - termed index of irreversibility - is proposed to quantify relative irreversibility of fracture kinematics. This new index can identify periods when fracture displacements are dominated by irreversible processes. For many sensors, irreversible enhanced fracture displacement is observed in summer and its initiation coincides with the onset of positive rock temperatures. This likely indicates thawing-related processes, such as meltwater percolation into fractures, as a forcing mechanism for irreversible displacements. For a few instrumented fractures, irreversible displacements were found at the onset of the freezing period, suggesting that cryogenic processes act as a driving factor through increasing ice pressure. The proposed analysis provides a tool for investigating and better understanding processes related to irreversible kinematics.

Magnetization dynamics of single-domain nanodots and minimum energy dissipation during either irreversible or reversible switching

NASA Astrophysics Data System (ADS)

Madami, Marco; Gubbiotti, Gianluca; Tacchi, Silvia; Carlotti, Giovanni

2017-11-01

Single- or multi-layered planar magnetic dots, with lateral dimensions ranging from tens to hundreds of nanometers, are used as elemental switches in current and forthcoming devices for information and communication technology (ICT), including magnetic memories, spin-torque oscillators and nano-magnetic logic gates. In this review article, we will first discuss energy dissipation during irreversible switching protocols of dots of different dimensions, ranging from a few tens of nanometers to the micrometric range. Then we will focus on the fundamental energy limits of adiabatic (slow) erasure and reversal of a magnetic nanodot, showing that dissipationless operation is achievable, provided that both dynamic reversibility (arbitrarily slow application of external fields) and entropic reversibility (no free entropy increase) are insured. However, recent theoretical and experimental tests of magnetic-dot erasure reveal that intrinsic defects related to materials imperfections such as roughness or polycrystallinity, may cause an excess of dissipation if compared to the minimum theoretical limit. We will conclude providing an outlook on the most promising strategies to achieve a new generation of power-saving nanomagnetic logic devices based on clusters of interacting dots and on straintronics.

Nonnucleoside reverse transcriptase inhibitor phenotypic hypersusceptibility can be demonstrated in different assays.

PubMed

Shulman, Nancy S; Delgado, Jamael; Bosch, Ronald J; Winters, Mark A; Johnston, Elizabeth; Shafer, Robert W; Katzenstein, David A; Merigan, Thomas C

2005-05-01

HIV-1 isolates harboring multiple nucleoside reverse transcriptase inhibitor (NRTI) resistance mutations are more susceptible ("hypersusceptible") to the nonnucleoside reverse transcriptase inhibitors (NNRTIs) than isolates lacking NRTI resistance mutations, but this has only been reported with a single-cycle replication phenotypic assay. In fact, there was a report that a commercial multicycle assay did not readily detect hypersusceptibility. To see whether NNRTI hypersusceptibility can be demonstrated in other types of phenotypic assays, including multicycle assays and enzyme inhibition assays. The susceptibility of HIV-1 clones derived from different patients in multicycle assays was tested in peripheral blood mononuclear cells (PBMCs) and in an established cell line. In addition, the reverse transcriptase (RT) of many of these clones was expressed and their susceptibility tested in an RT inhibition assay. Nevirapine and efavirenz susceptibilities were tested and compared with a control wild-type virus or RT. Hypersusceptibility to nevirapine and efavirenz was detected using each of the methods described above. R values correlating the other methods with single-cycle assay values were between 0.66 and 0.96. In addition to the high correlations, the different methods gave similar numeric results. NNRTI hypersusceptibility is readily seen in multicycle susceptibility assays and in enzyme inhibition assays.

RNA-templated single-base mutation detection based on T4 DNA ligase and reverse molecular beacon.

PubMed

Tang, Hongxing; Yang, Xiaohai; Wang, Kemin; Tan, Weihong; Li, Huimin; He, Lifang; Liu, Bin

2008-06-15

A novel RNA-templated single-base mutation detection method based on T4 DNA ligase and reverse molecular beacon (rMB) has been developed and successfully applied to identification of single-base mutation in codon 273 of the p53 gene. The discrimination was carried out using allele-specific primers, which flanked the variable position in the target RNA and was ligated using T4 DNA ligase only when the primers perfectly matched the RNA template. The allele-specific primers also carried complementary stem structures with end-labels (fluorophore TAMRA, quencher DABCYL), which formed a molecular beacon after RNase H digestion. One-base mismatch can be discriminated by analyzing the change of fluorescence intensity before and after RNase H digestion. This method has several advantages for practical applications, such as direct discrimination of single-base mismatch of the RNA extracted from cell; no requirement of PCR amplification; performance of homogeneous detection; and easily design of detection probes.

Monitoring the Single-Cell Stress Response of the Diatom Thalassiosira pseudonana by Quantitative Real-Time Reverse Transcription-PCR

PubMed Central

Shi, Xu; Gao, Weimin; Chao, Shih-hui

2013-01-01

Directly monitoring the stress response of microbes to their environments could be one way to inspect the health of microorganisms themselves, as well as the environments in which the microorganisms live. The ultimate resolution for such an endeavor could be down to a single-cell level. In this study, using the diatom Thalassiosira pseudonana as a model species, we aimed to measure gene expression responses of this organism to various stresses at a single-cell level. We developed a single-cell quantitative real-time reverse transcription-PCR (RT-qPCR) protocol and applied it to determine the expression levels of multiple selected genes under nitrogen, phosphate, and iron depletion stress conditions. The results, for the first time, provided a quantitative measurement of gene expression at single-cell levels in T. pseudonana and demonstrated that significant gene expression heterogeneity was present within the cell population. In addition, different expression patterns between single-cell- and bulk-cell-based analyses were also observed for all genes assayed in this study, suggesting that cell response heterogeneity needs to be taken into consideration in order to obtain accurate information that indicates the environmental stress condition. PMID:23315741

Monitoring the single-cell stress response of the diatom Thalassiosira pseudonana by quantitative real-time reverse transcription-PCR.

PubMed

Shi, Xu; Gao, Weimin; Chao, Shih-hui; Zhang, Weiwen; Meldrum, Deirdre R

2013-03-01

Directly monitoring the stress response of microbes to their environments could be one way to inspect the health of microorganisms themselves, as well as the environments in which the microorganisms live. The ultimate resolution for such an endeavor could be down to a single-cell level. In this study, using the diatom Thalassiosira pseudonana as a model species, we aimed to measure gene expression responses of this organism to various stresses at a single-cell level. We developed a single-cell quantitative real-time reverse transcription-PCR (RT-qPCR) protocol and applied it to determine the expression levels of multiple selected genes under nitrogen, phosphate, and iron depletion stress conditions. The results, for the first time, provided a quantitative measurement of gene expression at single-cell levels in T. pseudonana and demonstrated that significant gene expression heterogeneity was present within the cell population. In addition, different expression patterns between single-cell- and bulk-cell-based analyses were also observed for all genes assayed in this study, suggesting that cell response heterogeneity needs to be taken into consideration in order to obtain accurate information that indicates the environmental stress condition.

A history of reverse total shoulder arthroplasty.

PubMed

Flatow, Evan L; Harrison, Alicia K

2011-09-01

Management of the cuff-deficient arthritic shoulder has long been challenging. Early unconstrained shoulder arthroplasty systems were associated with high complication and implant failure rates. The evolution toward the modern reverse shoulder arthroplasty includes many variables of constrained shoulder arthroplasty designs. This review explores the development of reverse shoulder arthroplasty, specifically describing (1) the evolution of reverse shoulder arthroplasty designs, (2) the biomechanical variations in the evolution of this arthroplasty, and (3) the current issues relevant to reverse shoulder arthroplasty today. Using a PubMed search, the literature was explored for articles addressing reverse shoulder arthroplasty, focusing on those papers with historical context. Results of the early designs were apparently poor, although they were not subjected to rigorous clinical research and usually reported only in secondary literature. We identified a trend of glenoid component failure in the early reverse designs. This trend was recognized and reported by authors as the reverse shoulder evolved. Authors reported greater pain relief and better function in reverse shoulder arthroplasty with the fundamental change of Grammont's design (moving the center of rotation medially and distally). However, current reports suggest lingering concerns and challenges with today's designs. The history of reverse shoulder arthroplasty involves the designs of many forward-thinking surgeons. Many of these highly constrained systems failed, although more recent designs have demonstrated improved longevity and implant performance. Reverse shoulder arthroplasty requires ongoing study, with challenges and controversies remaining around present-day designs.

Genomic screening for blood-borne viruses in transfusion settings.

PubMed

Allain, J P

2000-02-01

The residual risk of post-transfusion human immunodeficiency virus (HIV) infection is low but slightly higher for hepatitis B virus (HBV) and hepatitis C virus (HCV), the main reason being viraemia during the window period preceding antibody or antigen detection by enzyme immunoassays. Immunosilent-infected individuals and carriers of distant viral variants also play an unquantifiable role. Multiple techniques, e.g. reverse transcription-polymerase chain reaction (RT-PCR), PCR, ligase-chain reaction, nucleic acid sequence-based amplification (NASBA) and transcription-mediated amplification (TMA) have been developed to amplify and detect viral genomes as single or multiplex assays. Equipment providing various degrees of automation has been adapted to these techniques. Applying nucleic acid amplification techniques (NAT) to blood screening, two main approaches have been advocated: plasma pool and single-donation testing. Pool testing presents the advantage of lower cost and readily available equipment although it is prone to false negative and positive reactions. The time required to identify infected donations is incompatible with blood component release, and may lead to product waste. Single-unit testing, although appealing, is not yet fully automated and potentially very costly unless a systematic multiplex approach is taken. Although technically feasible, NAT applied to the blood supply needs to be clinically evaluated and its cost efficiency assessed in the general public health context. However, pool NAT is currently implemented in continental Europe and the USA.

Production of the blood pressure lowing peptides from brown alga ( Undaria pinnatifida)

NASA Astrophysics Data System (ADS)

Minoru, Sato; Takashi, Oba; Takao, Hosokawa; Toshiyasu, Yamaguchi; Toshiki, Nakano; Tadao, Saito; Koji, Muramoto; Takashi, Kahara; Katsura, Funayama; Akio, Kobayashi; Takahisa, Nakano

2005-07-01

Brown alga ( Undaria pinnatifida) was treated with alginate lyase and hydrolyzed using 17 kinds of proteases and the inhibitory activity of the hydrolysates for the angiotensin-I-converting enzyme (ACE) was measured. Four hydrolysates with potent ACE-inhibitory activity were administered singly and orally to spontaneously hypertensive rats (SHRs). The systolic blood pressure of SHRs decreases significantly after single oral administration of the brown alga hydrolysates by protease S ‘Amano’ (from Bacillus stearothermophilus) at the concentration of 10 (mg protein) (kg body weight)-1. In the 17 weeks of feeding experiment, 7-week-old SHRs were fed standard diet supplemented with the brown alga hydrolysates for 10 weeks. In SHRs fed 1.0 and 0.1% brown alga hydrolysates, elevating of systolic bloodpressure was significantly suppressed for 7 weeks. To elucidate the active components, the brown alga hydrolysates were fractionated by 1-butanol extraction and HPLC on a reverse-phase column. Seven kinds of ACE-inhibitory peptides were isolated and identified by amino acid composition analysis, sequence analysis, and LC-MS with the results Val-Tyr, Ile-Tyr, Ala-Trp, Phe-Tyr, Val-Trp, Ile-Trp, and Leu-Trp. Each peptide was determined to have an antihypertensive effect after a single oral administration in SHRs. The brown alga hydrolysates were also confirmed to decrease the blood pressure in humans.

The reverse laser drilling of transparent materials

NASA Technical Reports Server (NTRS)

Anthony, T. R.; Lindner, P. A.

1980-01-01

Within a limited range of incident laser-beam intensities, laser drilling of a sapphire wafer initiates on the surface of the wafer where the laser beam exits and proceeds upstream in the laser beam to the surface where the laser beam enters the wafer. This reverse laser drilling is the result of the constructive interference between the laser beam and its reflected component on the exit face of the wafer. Constructive interference occurs only at the exit face of the sapphire wafer because the internally reflected laser beam suffers no phase change there. A model describing reverse laser drilling predicts the ranges of incident laser-beam intensity where no drilling, reverse laser drilling, and forward laser drilling can be expected in various materials. The application of reverse laser drilling in fabricating feed-through conductors in silicon-on-sapphire wafers for a massively parallel processer is described.

Bitter taste receptors as targets for tocolytics in preterm labor therapy.

PubMed

Zheng, Kaizhi; Lu, Ping; Delpapa, Ellen; Bellve, Karl; Deng, Ruitang; Condon, Jennifer C; Fogarty, Kevin; Lifshitz, Lawrence M; Simas, Tiffany A Moore; Shi, Fangxiong; ZhuGe, Ronghua

2017-09-01

Preterm birth (PTB) is the leading cause of neonatal mortality and morbidity, with few prevention and treatment options. Uterine contraction is a central feature of PTB, so gaining new insights into the mechanisms of this contraction and consequently identifying novel targets for tocolytics are essential for more successful management of PTB. Here we report that myometrial cells from human and mouse express bitter taste receptors (TAS2Rs) and their canonical signaling components ( i.e., G-protein gustducin and phospholipase C β2). Bitter tastants can completely relax myometrium precontracted by different uterotonics. In isolated single mouse myometrial cells, a phenotypical bitter tastant (chloroquine, ChQ) reverses the rise in intracellular Ca 2+ concentration ([Ca 2+ ] i ) and cell shortening induced by uterotonics, and this reversal effect is inhibited by pertussis toxin and by genetic deletion of α-gustducin. In human myometrial cells, knockdown of TAS2R14 but not TAS2R10 inhibits ChQ's reversal effect on an oxytocin-induced rise in [Ca 2+ ] i Finally, ChQ prevents mouse PTBs induced by bacterial endotoxin LPS or progesterone receptor antagonist mifepristone more often than current commonly used tocolytics, and this prevention is largely lost in α-gustducin-knockout mice. Collectively, our results reveal that activation of the canonical TAS2R signaling system in myometrial cells produces profound relaxation of myometrium precontracted by a broad spectrum of contractile agonists, and that targeting TAS2Rs is an attractive approach to developing effective tocolytics for PTB management.-Zheng, K., Lu, P., Delpapa, E., Bellve, K., Deng, R., Condon, J. C., Fogarty, K., Lifshitz, L. M., Simas, T. A. M., Shi, F., ZhuGe, R. Bitter taste receptors as targets for tocolytics in preterm labor therapy. © FASEB.

Isolation of a candidate human telomerase catalytic subunit gene, which reveals complex splicing patterns in different cell types.

PubMed

Kilian, A; Bowtell, D D; Abud, H E; Hime, G R; Venter, D J; Keese, P K; Duncan, E L; Reddel, R R; Jefferson, R A

1997-11-01

Telomerase is a multicomponent reverse transcriptase enzyme that adds DNA repeats to the ends of chromosomes using its RNA component as a template for synthesis. Telomerase activity is detected in the germline as well as the majority of tumors and immortal cell lines, and at low levels in several types of normal cells. We have cloned a human gene homologous to a protein from Saccharomyces cerevisiae and Euplotes aediculatus that has reverse transcriptase motifs and is thought to be the catalytic subunit of telomerase in those species. This gene is present in the human genome as a single copy sequence with a dominant transcript of approximately 4 kb in a human colon cancer cell line, LIM1215. The cDNA sequence was determined using clones from a LIM1215 cDNA library and by RT-PCR, cRACE and 3'RACE on mRNA from the same source. We show that the gene is expressed in several normal tissues, telomerase-positive post-crisis (immortal) cell lines and various tumors but is not expressed in the majority of normal tissues analyzed, pre-crisis (non-immortal) cells and telomerase-negative immortal (ALT) cell lines. Multiple products were identified by RT-PCR using primers within the reverse transcriptase domain. Sequencing of these products suggests that they arise by alternative splicing. Strikingly, various tumors, cell lines and even normal tissues (colonic crypt and testis) showed considerable differences in the splicing patterns. Alternative splicing of the telomerase catalytic subunit transcript may be important for the regulation of telomerase activity and may give rise to proteins with different biochemical functions.

Genetic and Transcriptomic Bases of Intestinal Epithelial Barrier Dysfunction in Inflammatory Bowel Disease.

PubMed

Vancamelbeke, Maaike; Vanuytsel, Tim; Farré, Ricard; Verstockt, Sare; Ferrante, Marc; Van Assche, Gert; Rutgeerts, Paul; Schuit, Frans; Vermeire, Séverine; Arijs, Ingrid; Cleynen, Isabelle

2017-10-01

Intestinal barrier defects are common in patients with inflammatory bowel disease (IBD). To identify which components could underlie these changes, we performed an in-depth analysis of epithelial barrier genes in IBD. A set of 128 intestinal barrier genes was selected. Polygenic risk scores were generated based on selected barrier gene variants that were associated with Crohn's disease (CD) or ulcerative colitis (UC) in our study. Gene expression was analyzed using microarray and quantitative reverse transcription polymerase chain reaction. Influence of barrier gene variants on expression was studied by cis-expression quantitative trait loci mapping and comparing patients with low- and high-risk scores. Barrier risk scores were significantly higher in patients with IBD than controls. At single-gene level, the associated barrier single-nucleotide polymorphisms were most significantly enriched in PTGER4 for CD and HNF4A for UC. As a group, the regulating proteins were most enriched for CD and UC. Expression analysis showed that many epithelial barrier genes were significantly dysregulated in active CD and UC, with overrepresentation of mucus layer genes. In uninflamed CD ileum and IBD colon, most barrier gene levels restored to normal, except for MUC1 and MUC4 that remained persistently increased compared with controls. Expression levels did not depend on cis-regulatory variants nor combined genetic risk. We found genetic and transcriptomic dysregulations of key epithelial barrier genes and components in IBD. Of these, we believe that mucus genes, in particular MUC1 and MUC4, play an essential role in the pathogenesis of IBD and could represent interesting targets for treatment.

[Separation and purification of the components in Trachelospermum jasminoides by two dimensional hydrophilic interaction liquid chromatography- reversed-phase liquid chromatography].

PubMed

Jia, Youmei; Cai, Jianfeng; Xin, Huaxia; Feng, Jiatao; Fu, Yanhui; Fu, Qing; Jin, Yu

2017-06-08

A preparative two dimensional hydrophilic interaction liquid chromatography/reversed-phase liquid chromatography (Pre-2D-HILIC/RPLC) method was established to separate and purify the components in Trachelospermum jasminoides . The pigments and strongly polar components were removed from the crude extract after the active carbon decolorization and solid phase extraction processes. A Click XIon column (250 mm×20 mm, 10 μm) was selected as stationary phase and water-acetonitrile as mobile phases in the first dimensional HILIC. Finally, 15 fractions were collected under UV-triggered mode. In the second dimensional RPLC, a C18 column (250 mm×20 mm, 5 μm) was selected and water-acetonitrile was used as mobile phases. As a result, 14 compounds with high purity were obtained, which were further identified by mass spectrometry (MS) and nuclear magnetic resonance (NMR). Finally, 11 lignan compounds and three flavonoid compounds were obtained. The method has a good orthogonality, and can improve the resolution and the peak capacity. It is significant for the separation of complex components from Trachelospermum jasminoides .

One Hundred Eighty Day Subchronic Oral Toxicity Study of Pyridostigmine Bromide in Rats. Volume 1

DTIC Science & Technology

1990-06-01

has proposed a treatment regimen incorporating prophylaxis with a reversible cholinesterase inhibitor and, following nerve agent exposure, antidotal...would accomplish two goals: the oxime would abate the inhibition induced by the reversible cholinesterase inhibitor prophylaxis, and the atropine will...cholinesterase inhibitor as the pretreatment component of a therapeutic regimen that would include antidotal therapy with 2-PAM chloride and atropine. A

Bony increased-offset reversed shoulder arthroplasty: minimizing scapular impingement while maximizing glenoid fixation.

PubMed

Boileau, Pascal; Moineau, Grégory; Roussanne, Yannick; O'Shea, Kieran

2011-09-01

Scapular notching, prosthetic instability, limited shoulder rotation and loss of shoulder contour are associated with conventional medialized design reverse shoulder arthroplasty. Prosthetic (ie, metallic) lateralization increases torque at the baseplate-glenoid interface potentially leading to failure. We asked whether bony lateralization of reverse shoulder arthroplasty would avoid the problems caused by humeral medialization without increasing torque or shear force applied to the glenoid component. We prospectively followed 42 patients with rotator cuff deficiency treated with bony increased-offset reverse shoulder arthroplasty. A cylinder of autologous cancellous bone graft, harvested from the humeral head, was placed between the reamed glenoid surface and baseplate. Graft and baseplate fixation was achieved using a lengthened central peg (25 mm) and four screws. Patients underwent clinical, radiographic, and CT assessment at a minimum of 2 years after surgery. The humeral graft incorporated completely in 98% of cases (41 of 42) and partially in one. At a mean of 28 months postoperatively, no graft resorption, glenoid loosening, or postoperative instability was observed. Inferior scapular notching occurred in 19% (eight of 42). The absolute Constant-Murley score improved from 31 to 67. Thirty-six patients (86%) were able to internally rotate sufficiently to reach their back over the sacrum. Grafting of the glenoid surface during reverse shoulder arthroplasty effectively creates a long-necked scapula, providing the benefits of lateralization. Bony increased-offset reverse shoulder arthroplasty is associated with low rates of inferior scapular notching, improved shoulder rotation, no prosthetic instability and improved shoulder contour. In contrast to metallic lateralization, bony lateralization has the advantage of maintaining the prosthetic center of rotation at the prosthesis-bone interface, thus minimizing torque on the glenoid component. Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Dynamic simulation of a reverse Brayton refrigerator

NASA Astrophysics Data System (ADS)

Peng, N.; Lei, L. L.; Xiong, L. Y.; Tang, J. C.; Dong, B.; Liu, L. Q.

2014-01-01

A test refrigerator based on the modified Reverse Brayton cycle has been developed in the Chinese Academy of Sciences recently. To study the behaviors of this test refrigerator, a dynamic simulation has been carried out. The numerical model comprises the typical components of the test refrigerator: compressor, valves, heat exchangers, expander and heater. This simulator is based on the oriented-object approach and each component is represented by a set of differential and algebraic equations. The control system of the test refrigerator is also simulated, which can be used to optimize the control strategies. This paper describes all the models and shows the simulation results. Comparisons between simulation results and experimental data are also presented. Experimental validation on the test refrigerator gives satisfactory results.

Analysis of antimycin A by reversed-phase liquid chromatography/nuclear magnetic-resonance spectrometry

USGS Publications Warehouse

Ha, Steven T.K.; Wilkins, Charles L.; Abidi, Sharon L.

1989-01-01

A mixture of closely related streptomyces fermentation products, antimycin A, Is separated, and the components are identified by using reversed-phase high-performance liquid chromatography with directly linked 400-MHz proton nuclear magnetic resonance detection. Analyses of mixtures of three amino acids, alanine, glycine, and valine, are used to determine optimal measurement conditions. Sensitivity increases of as much as a factor of 3 are achieved, at the expense of some loss in chromatographic resolution, by use of an 80-μL NMR cell, Instead of a smaller 14-μL cell. Analysis of the antimycin A mixture, using the optimal analytical high performance liquid chromatography/nuclear magnetic resonance conditions, reveals it to consist of at least 10 closely related components.

Austenitic Reversion of Cryo-rolled Ti-Stabilized Austenitic Stainless Steel: High-Resolution EBSD Investigation

NASA Astrophysics Data System (ADS)

Tiamiyu, A. A.; Odeshi, A. G.; Szpunar, J. A.

2018-02-01

In this study, AISI 321 austenitic stainless steel (ASS) was cryo-rolled and subsequently annealed at 650 and 800 °C to reverse BCC α'-martensite to FCC γ-austenite. The texture evolution associated with the reversion at the selected temperatures was investigated using high-resolution EBSD. After the reversion, TiC precipitates were observed to be more stable in 650 °C-annealed specimens than those reversed at 800 °C. {110} texture was mainly developed in specimens subjected to both annealing temperatures. However, specimens reversed at 650 °C have stronger texture than those annealed at 800 °C, even at the higher annealing time. The strong intensity of {110} texture component is attributed to the ability of AISI 321 ASS to memorize the crystallographic orientation of the deformed austenite, a phenomenon termed texture memory. The development of weaker texture in 800 °C-annealed specimens is attributed to the residual strain relief in grains, dissolution of grain boundary precipitates, and an increase in atomic migration along the grain boundaries. Based on the observed features of the reversed austenite grains and estimation from an existing model, it is suspected that the austenite reversion at 650 and 800 °C undergone diffusional and martensitic shear reversion, respectively.

Direct measurement of photomechanical switching cross-sections of single-molecules on a surface

NASA Astrophysics Data System (ADS)

Cho, Jongweon; Comstock, Matthew J.; Levy, Niv; Berbil-Bautista, Luis; Lauterwasser, Frank; Frechet, Jean M. J.; Crommie, Michael F.

2008-03-01

The photomechanical switching of photoactive molecules in solution strongly depends on the wavelength of light. This dependence is crucial to reliably control the photomechanical state of target molecules. Recently, reversible photomechanical switching of individual azobenzene molecular derivatives on the Au(111) surface has been reported for one particular wavelength of UV illumination [1]. To further understand this process and its possible applications in future nanotechnologies, we have investigated photomechanical switching rates and saturation behavior for azobenzene molecular derivatives at a surface under optical stimulation at different wavelengths. Using single-molecule-resolved scanning tunneling microscopy, we have determined both the forward and reverse photomechanical molecular switching cross-sections at different wavelengths. In a dramatic departure from solution-based environments, visible light does not efficiently reverse the photoreaction. [1] Matthew J. Comstock, Niv Levy, Armen Kirakosian, Jongweon Cho, Frank Lauterwasser, Jessica H. Harvey, David A. Strubbe, Jean M. J. Fr'echet, Dirk Trauner, Steven G. Louie, and Michael F. Crommie, Phys. Rev. Lett. 99, 038301 (2007)

Reversible solvatomagnetic switching in a single-ion magnet from an entatic state.

PubMed

Vallejo, J; Pardo, E; Viciano-Chumillas, M; Castro, I; Amorós, P; Déniz, M; Ruiz-Pérez, C; Yuste-Vivas, C; Krzystek, J; Julve, M; Lloret, F; Cano, J

2017-05-01

A vast impact on molecular nanoscience can be achieved using simple transition metal complexes as dynamic chemical systems to perform specific and selective tasks under the control of an external stimulus that switches "ON" and "OFF" their electronic properties. While the interest in single-ion magnets (SIMs) lies in their potential applications in information storage and quantum computing, the switching of their slow magnetic relaxation associated with host-guest processes is insufficiently explored. Herein, we report a unique example of a mononuclear cobalt(ii) complex in which geometrical constraints are the cause of easy and reversible water coordination and its release. As a result, a reversible and selective colour and SIM behaviour switch occurs between a "slow-relaxing" deep red anhydrous material (compound 1 ) and its "fast-relaxing" orange hydrated form (compound 2 ). The combination of this optical and magnetic switching in this new class of vapochromic and thermochromic SIMs offers fascinating possibilities for designing multifunctional molecular materials.

Large effect of columnar defects on the thermodynamic properties of Bi2Sr2CaCu2O8 single crystals

NASA Astrophysics Data System (ADS)

van der Beek, C. J.; Konczykowski, M.; Li, T. W.; Kes, P. H.; Benoit, W.

1996-07-01

The introduction of columnar defects by irradiation with 5.8-GeV Pb ions is shown to affect significantly the reversible magnetic properties of Bi2Sr2CaCu2O8+δ single crystals. Notably, the suppression of superconducting fluctuations on length scales greater than the separation between columns leads to the disappearance of the ``crossing point'' in the critical fluctuation regime. At lower temperatures, the strong modification of the vortex energy due to pinning leads to an important change of the reversible magnetization. The analysis of the latter permits the direct determination of the pinning energy.

Genome-based approaches to develop vaccines against bacterial pathogens.

PubMed

Serruto, Davide; Serino, Laura; Masignani, Vega; Pizza, Mariagrazia

2009-05-26

Bacterial infectious diseases remain the single most important threat to health worldwide. Although conventional vaccinology approaches were successful in conferring protection against several diseases, they failed to provide efficacious solutions against many others. The advent of whole-genome sequencing changed the way to think about vaccine development, enabling the targeting of possible vaccine candidates starting from the genomic information of a single bacterial isolate, with a process named reverse vaccinology. As the genomic era progressed, reverse vaccinology has evolved with a pan-genome approach and multi-strain genome analysis became fundamental for the design of universal vaccines. This review describes the applications of genome-based approaches in the development of new vaccines against bacterial pathogens.

Effects of the resistivity profile on the formation of a reversed configuration and single helicity states in compressible simulations of the reversed-field pinch

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

Onofri, M.; Malara, F.

2013-10-15

Compressible magnetohydrodynamics simulations of the reversed-field pinch (RFP) are presented. Previous simulations of the RFP, including density and pressure evolution, showed that a stationary state with a reversed toroidal magnetic field could not be obtained, contrary to the results produced with numerical codes neglecting density and pressure dynamics. The simulations described in the present paper show that including density and pressure evolution, a stationary RFP configuration can be obtained if the resistivity has a radial profile steeply increasing close to the wall. Such resistivity profile is more realistic than a uniform resistivity, since the temperature at the wall is lowermore » than in the plasma core.« less

WWC Review of the Report "Conceptualizing Astronomical Scale: Virtual Simulations on Handheld Tablet Computers Reverse Misconceptions." What Works Clearinghouse Single Study Review

ERIC Educational Resources Information Center

What Works Clearinghouse, 2014

2014-01-01

The 2014 study, "Conceptualizing Astronomical Scale: Virtual Simulations on Handheld Tablet Computers Reverse Misconceptions," examined the effects of using the true-to-scale (TTS) display mode versus the orrery display mode in the iPad's Solar Walk software application on students' knowledge of the Earth's place in the solar system. The…

[Safety Evaluation of Rare Sugar Syrup: Single-dose Oral Toxicity in Rats, Reverse Mutation Assay, Chromosome Aberration Assay, and Acute Non-Effect Level for Diarrhea of a Single Dose in Humans].

PubMed

Yamada, Takako; Iida, Tetsuo; Takamine, Satoshi; Hayashi, Noriko; Okuma, Kazuhiro

2015-01-01

The safety of rare sugar syrup obtained from high-fructose corn syrup under slightly alkaline conditions was studied. Mutagenicity of rare sugar syrup was assessed by a reverse mutation assay using Salmonella typhimurium and Escherichia coli, and an in vitro chromosomal aberration assay using Chinese hamster lung cell line (CHL/IU). No mutagenicity of rare sugar syrup was detected under these experimental conditions. Oral administration of single dose (15,000 mg/kg) of rare sugar syrup to rats caused no abnormalities, suggesting no adverse effect of rare sugar syrup. In humans, the acute non-effect level of rare sugar syrup for causing diarrhea was estimated as 0.9 g/kg body weight as dry solid base in both males and females.

Quantum Stirling heat engine and refrigerator with single and coupled spin systems

NASA Astrophysics Data System (ADS)

Huang, Xiao-Li; Niu, Xin-Ya; Xiu, Xiao-Ming; Yi, Xue-Xi

2014-02-01

We study the reversible quantum Stirling cycle with a single spin or two coupled spins as the working substance. With the single spin as the working substance, we find that under certain conditions the reversed cycle of a heat engine is NOT a refrigerator, this feature holds true for a Stirling heat engine with an ion trapped in a shallow potential as its working substance. The efficiency of quantum Stirling heat engine can be higher than the efficiency of the Carnot engine, but the performance coefficient of the quantum Stirling refrigerator is always lower than its classical counterpart. With two coupled spins as the working substance, we find that a heat engine can turn to a refrigerator due to the increasing of the coupling constant, this can be explained by the properties of the isothermal line in the magnetic field-entropy plane.

[CoCuMnOx Photocatalyzed Oxidation of Multi-component VOCs and Kinetic Analysis].

PubMed

Meng, Hai-long; Bo, Long-li; Liu, Jia-dong; Gao, Bo; Feng, Qi-qi; Tan, Na; Xie, Shuai

2016-05-15

Solar energy absorption coating CoCuMnOx was prepared by co-precipitation method and applied to photodegrade multi- component VOCs including toluene, ethyl acetate and acetone under visible light irradiation. The photocatalytic oxidation performance of toluene, ethyl acetate and acetone was analyzed and reaction kinetics of VOCs were investigated synchronously. The research indicated that removal rates of single-component toluene, ethyl acetate and acetone were 57%, 62% and 58% respectively under conditions of 400 mg · m⁻³ initial concentration, 120 mm illumination distance, 1 g/350 cm² dosage of CoCuMnOx and 6 h of irradiation time by 100 W tungsten halogen lamp. Due to the competition among different VOCs, removal efficiencies in three-component mixture were reduced by 5%-26% as compared with single VOC. Degradation processes of single-component VOC and three-component VOCs both fitted pseudo first order reaction kinetics, and kinetic constants of toluene, ethyl acetate and acetone were 0.002, 0.002 8 and 0.002 33 min⁻¹ respectively under single-component condition. Reaction rates of VOCs in three-component mixture were 0.49-0.88 times of single components.

Neural Correlates of Letter Reversal in Children and Adults

PubMed Central

Kalra, Priya; Yee, Debbie; Sinha, Pawan; Gabrieli, John D. E.

2014-01-01

Children often make letter reversal errors when first learning to read and write, even for letters whose reversed forms do not appear in normal print. However, the brain basis of such letter reversal in children learning to read is unknown. The present study compared the neuroanatomical correlates (via functional magnetic resonance imaging) and the electrophysiological correlates (via event-related potentials or ERPs) of this phenomenon in children, ages 5–12, relative to young adults. When viewing reversed letters relative to typically oriented letters, adults exhibited widespread occipital, parietal, and temporal lobe activations, including activation in the functionally localized visual word form area (VWFA) in left occipito-temporal cortex. Adults exhibited significantly greater activation than children in all of these regions; children only exhibited such activation in a limited frontal region. Similarly, on the P1 and N170 ERP components, adults exhibited significantly greater differences between typical and reversed letters than children, who failed to exhibit significant differences between typical and reversed letters. These findings indicate that adults distinguish typical and reversed letters in the early stages of specialized brain processing of print, but that children do not recognize this distinction during the early stages of processing. Specialized brain processes responsible for early stages of letter perception that distinguish between typical and reversed letters may develop slowly and remain immature even in older children who no longer produce letter reversals in their writing. PMID:24859328

Formation of highly structured cubic micellar lipid nanoparticles of soy phosphatidylcholine and glycerol dioleate and their degradation by triacylglycerol lipase.

PubMed

Wadsäter, Maria; Barauskas, Justas; Nylander, Tommy; Tiberg, Fredrik

2014-05-28

Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/glycerol dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5-10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narrow size distribution and exhibit good long-term stability. In pharmaceutical applications, biodegradation pathways of the drug delivery vehicles and their components are important considerations. In the second part of the study we show how the structure of the particles evolves during exposure to a triacylglycerol lipase (TGL) under physiological-like temperature and pH. TGL catalyzes the lipolytic degradation of acylglycerides, such as GDO, to monoglycerides, glycerol, and free fatty acids. During the degradation, the interior phase of the particles is shown to undergo continuous phase transitions from the reversed I2 structure to structures of less negative curvature (2D hexagonal, bicontinuous cubic, and sponge), ultimately resulting in the formation of multilamellar vesicles.

Elimination of the negative component of the unipolar atrial electrogram as an in vivo marker of transmural lesion creation: acute study in canines.

PubMed

Bortone, Agustín; Brault-Noble, Guillaume; Appetiti, Anthony; Marijon, Eloi

2015-08-01

It has been experimentally shown that elimination of the negative component of the unipolar atrial electrogram (R morphology completion) during radiofrequency applications reflects transmural lesions creation. Subsequently, it has been clinically suggested that such a transmurality can be either irreversible or reversible. The present study is aimed to determine, at the histological level, whether transmural lesions, assessed by R morphology completion, might indeed be reversible in some circumstances or not. In 6 Mongrel hound dogs, superior and inferior vena cavae were isolated and individual lesions were created in the right atrium using radiofrequency energy (30 W/48°C/17 mL/min as presettings and 10g of force in average) under CARTO guidance. Five types of lesions were created; R+0: termination of ablation at the time of R morphology completion; R+5, R+10, or R+20: extension of ablation for 5, 10, or 20 seconds, respectively, after R morphology achievement; and conventional: radiofrequency applications lasting 30 seconds irrespective of the atrial electrogram modification. All conventional, R+5, R+10, and R+20 lesions were necrotic and transmural, whereas some R+0 lesions were not (comprising a part of necrosis and a part of reversible cell damage). Interestingly, surrounding organ injuries were observed after conventional, R+10, and R+20 radiofrequency applications but were not observed after R+0 and R+5 applications. Elimination of the negative component of the unipolar atrial electrogram reflects, in general, irreversible transmural necrosis creation. In some cases, however, it translates transmural lesion only (with potential reversibility) likely related to transient cell damage creation. © 2015 American Heart Association, Inc.

Affinity-reversed-phase liquid chromatography assay to quantitate recombinant antibodies and antibody fragments in fermentation broth.

PubMed

Battersby, J E; Snedecor, B; Chen, C; Champion, K M; Riddle, L; Vanderlaan, M

2001-08-24

An automated dual-column liquid chromatography assay comprised of affinity and reversed-phase separations that quantifies the majority of antibody-related protein species found in crude cell extracts of recombinant origin is described. Although potentially applicable to any antibody preparation, we here use samples of anti-CD18 (Fab'2LZ) and a full-length antibody, anti-tissue factor (anti-TF), from various stages throughout a biopharmaceutical production process to describe the assay details. The targeted proteins were captured on an affinity column containing an anti-light-chain (kappa) Fab antibody (AME5) immobilized on controlled pore glass. The affinity column was placed in-line with a reversed-phase column and the captured components were transferred by elution with dilute acid and subsequently resolved by eluting the reversed-phase column with a shallow acetonitrile gradient. Characterization of the resolved components showed that most antibody fragment preparations contained a light-chain fragment, free light chain, light-chain dimer and multiple forms of Fab'. Analysis of full-length antibody preparations also resolved these fragments as well as a completely assembled form. Co-eluting with the full-length antibody were high-molecular-mass variants that were missing one or both light chains. Resolved components were quantified by comparison with peak areas of similarly treated standards. By comparing the two-dimensional polyacrylamide gel electrophoresis patterns of an Escherichia coli blank run, a production run and the material affinity captured (AME5) from a production run, it was determined that the AME5 antibody captured isoforms of light chain, light chain covalently attached to heavy chain, and truncated light chain isoforms. These forms comprise the bulk of the soluble product-related fragments found in E. coli cell extracts of recombinantly produced antibody fragments.

The Fractions SNARC Revisited: Processing Fractions on a Consistent Mental Number Line.

PubMed

Toomarian, Elizabeth Y; Hubbard, Edward M

2017-07-12

The ability to understand fractions is key to establishing a solid foundation in mathematics, yet children and adults struggle to comprehend them. Previous studies have suggested that these struggles emerge because people fail to process fraction magnitude holistically on the mental number line (MNL), focusing instead on fraction components (Bonato et al. 2007). Subsequent studies have produced evidence for default holistic processing (Meert et al., 2009; 2010), but examined only magnitude processing, not spatial representations. We explored the spatial representations of fractions on the MNL in a series of three experiments: Experiment 1 replicated Bonato et al. (2007); 30 naïve undergraduates compared unit fractions (1/1-1/9) to 1/5, resulting in a reverse SNARC effect. Experiment 2 countered potential strategic biases induced by the limited set of fractions used by Bonato et al. by expanding the stimulus set to include all irreducible, single-digit proper fractions, and asked participants to compare them against 1/2. We observed a classic SNARC effect, completely reversing the pattern from Experiment 1. Together, Experiments 1 and 2 demonstrate that stimulus properties dramatically impact spatial representations of fractions. In Experiment 3, we demonstrated within-subjects reliability of the SNARC effect across both a fractions and whole number comparison task. Our results suggest that adults can indeed process fraction magnitudes holistically, and that their spatial representations occur on a consistent MNL for both whole numbers and fractions.

Global Kinetic Analysis of Mammalian E3 Reveals pH-dependent NAD+/NADH Regulation, Physiological Kinetic Reversibility, and Catalytic Optimum*

PubMed Central

Moxley, Michael A.; Beard, Daniel A.; Bazil, Jason N.

2016-01-01

Mammalian E3 is an essential mitochondrial enzyme responsible for catalyzing the terminal reaction in the oxidative catabolism of several metabolites. E3 is a key regulator of metabolic fuel selection as a component of the pyruvate dehydrogenase complex (PDHc). E3 regulates PDHc activity by altering the affinity of pyruvate dehydrogenase kinase, an inhibitor of the enzyme complex, through changes in reduction and acetylation state of lipoamide moieties set by the NAD+/NADH ratio. Thus, an accurate kinetic model of E3 is needed to predict overall mammalian PDHc activity. Here, we have combined numerous literature data sets and new equilibrium spectroscopic experiments with a multitude of independently collected forward and reverse steady-state kinetic assays using pig heart E3. The latter kinetic assays demonstrate a pH-dependent transition of NAD+ activation to inhibition, shown here, to our knowledge, for the first time in a single consistent data set. Experimental data were analyzed to yield a thermodynamically constrained four-redox-state model of E3 that simulates pH-dependent activation/inhibition and active site redox states for various conditions. The developed model was used to determine substrate/product conditions that give maximal E3 rates and show that, due to non-Michaelis-Menten behavior, the maximal flux is different compared with the classically defined kcat. PMID:26644471

Asymmetry in the Farley-Buneman dispersion relation caused by parallel electric fields

NASA Astrophysics Data System (ADS)

Forsythe, Victoriya V.; Makarevich, Roman A.

2016-11-01

An implicit assumption utilized in studies of E region plasma waves generated by the Farley-Buneman instability (FBI) is that the FBI dispersion relation and its solutions for the growth rate and phase velocity are perfectly symmetric with respect to the reversal of the wave propagation component parallel to the magnetic field. In the present study, a recently derived general dispersion relation that describes fundamental plasma instabilities in the lower ionosphere including FBI is considered and it is demonstrated that the dispersion relation is symmetric only for background electric fields that are perfectly perpendicular to the magnetic field. It is shown that parallel electric fields result in significant differences between the growth rates and phase velocities for propagation of parallel components of opposite signs. These differences are evaluated using numerical solutions of the general dispersion relation and shown to exhibit an approximately linear relationship with the parallel electric field near the E region peak altitude of 110 km. An analytic expression for the differences is also derived from an approximate version of the dispersion relation, with comparisons between numerical and analytic results agreeing near 110 km. It is further demonstrated that parallel electric fields do not change the overall symmetry when the full 3-D wave propagation vector is reversed, with no symmetry seen when either the perpendicular or parallel component is reversed. The present results indicate that moderate-to-strong parallel electric fields of 0.1-1.0 mV/m can result in experimentally measurable differences between the characteristics of plasma waves with parallel propagation components of opposite polarity.

Effect of baseplate size on primary glenoid stability and impingement-free range of motion in reverse shoulder arthroplasty.

PubMed

Chae, Soo-Won; Kim, Soung-Yon; Lee, Haea; Yon, Joung-Ro; Lee, Juneyoung; Han, Seung-Ho

2014-12-09

Use of a baseplate with a smaller diameter in reverse shoulder arthroplasty is increasing, especially in patients with a small glenoid or glenoid wear. However, the effect of a smaller baseplate on stability of the glenoid component has not been evaluated. Thus, the purpose of this study was to determine whether a smaller baseplate (25 mm) is beneficial to the initial stability of the glenoid component compared to that with a baseplate of a commonly used size (29 mm). Micromotion of glenoid components attached to 14 scapulae of fresh-frozen cadavers was measured and compared between 25- and 29-mm baseplates in biomechanical testing. Impingement-free range of motion in abduction, adduction, internal rotation, and external rotation was evaluated by using a simulated computer model constructed based on the same fresh-frozen cadavers used in biomechanical testing. Micromotion at the inferior third of the glenoid-glenosphere interface was higher in the 29-mm baseplate group than in the 25-mm baseplate group during both 0.7- and 1-body weight cyclic loading in biomechanical testing. Adduction deficit was smaller, and total impingement-free range of motion from abduction to adduction and rotation were greater in the 25-mm baseplate group than in the 29-mm baseplate group in the simulated computer model. Use of a baseplate with a smaller diameter (25 mm) in reverse shoulder arthroplasty is suitable for improving the primary stability of the glenoid component. With a smaller baseplate, impingement-free range of motion is optimized in a smaller glenoid.

Inherited XX sex reversal originating from wild medaka populations.

PubMed

Shinomiya, A; Otake, H; Hamaguchi, S; Sakaizumi, M

2010-11-01

The teleost fish, medaka (Oryzias latipes), has an XX/XY sex-determining mechanism. A Y-linked DM domain gene, DMY, has been isolated by positional cloning as the sex-determining gene in this species. Previously, we conducted a field survey of genotypic sex and found that approximately 1% of wild medaka are sex-reversed (XX males and XY females). Here, we performed genetic analyses of nine spontaneous XX sex-reversed males to elucidate its genetic basis. In all cases, the F(1) progeny were all females, whereas XX males reappeared in the backcross (BC) progeny, suggesting that XX sex reversal is a recessive trait. Although the incidences of sex reversal in the BC progeny were mostly low, 40% were males derived from one XX male. We performed linkage analysis using 55 BC males and located a single major factor, sda-1 (sex-determining autosomal factor-1), controlling sex reversal in an autosomal linkage group. Thus, genes involved in the sex-determining pathway can be isolated from spontaneous mutants in wild populations.

Relaxation models for single helical reversed field pinch plasmas

NASA Astrophysics Data System (ADS)

Paccagnella, Roberto

2016-09-01

In this paper, a relaxation theory for plasmas where a single dominant mode is present [Bhattacharjee et al., Phys. Rev. Lett. 45, 347 (1980)], is revisited. The solutions of a related eigenvalue problem are numerically calculated and discussed. Although these solutions can reproduce well, the magnetic fields measured in experiments, there is no way within the theory to determine the dominant mode, whose pitch is a free parameter in the model. To find the preferred helical perturbation, a procedure is proposed that minimizes the "distance" of the relaxed state from a state which is constructed as a two region generalization of the Taylor's relaxation model [Taylor, Phys. Rev. Lett. 33, 1139 (1974); Rev. Mod. Phys. 58, 751 (1986)] and that allows current discontinuities. It is found that this comparison is able to predict the observed scaling with the aspect ratio and reversal parameter for the dominant mode in the Single Helical states. The aspect ratio scaling alone is discussed in a previous paper [Paccagnella, Nucl. Fusion 56, 046010 (2016)] in terms of the efficient response of a toroidal shell to specific modes (leaving a sign undetermined), showing that the ideal wall boundary condition, a key ingredient in relaxation theories, is particularly well matched for them. Therefore, the present paper altogether [Paccagnella, Nucl. Fusion 56, 046010 (2016)] can give a new and satisfactory explanation of some robust and reproducible experimental facts observed in the Single Helical Reversed Field Pinch plasmas and never explained before.

Evaluation of Military Field-Water Quality. Volume 8. Performance of Mobile Water-Purification Unit (MWPU) and Pretreatment Components of the 600-GPH Reverse Osmosis Water Purification Unit (ROWPU), and Consideration of Reverse Osmosis (RO) Bypass, Potable-Water Disinfection, and Water-Quality Analysis Techniques

DTIC Science & Technology

1990-05-01

Health Risks in Potential Theaters of Operation for U.S. Military Forces. The nine volumes of this study contain a comprehensive assessment of the chemical...module. The percentage of total free chlorine ( hypochlorous acid , HOCl) plus hypochlorlte ion (OClN), measured by the Model 453 membrane sensor, varies...between the performances of the 600-Sph Reverse Osmosis Water Purification Unit (ROWPU) operated in the bypass node and ’the Mobile Water Purification

Two-step ion-exchange chromatographic purification combined with reversed-phase chromatography to isolate C-peptide for mass spectrometric analysis.

PubMed

Kabytaev, Kuanysh; Durairaj, Anita; Shin, Dmitriy; Rohlfing, Curt L; Connolly, Shawn; Little, Randie R; Stoyanov, Alexander V

2016-02-01

A liquid chromatography with mass spectrometry on-line platform that includes the orthogonal techniques of ion exchange and reversed phase chromatography is applied for C-peptide analysis. Additional improvement is achieved by the subsequent application of cation- and anion-exchange purification steps that allow for isolating components that have their isoelectric points in a narrow pH range before final reversed-phase mass spectrometry analysis. The utility of this approach for isolating fractions in the desired "pI window" for profiling complex mixtures is discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Inferior tilt fixation of the glenoid component in reverse total shoulder arthroplasty: A biomechanical study.

PubMed

Chae, S W; Lee, J; Han, S H; Kim, S-Y

2015-06-01

Glenoid component fixation with an inferior tilt has been suggested to decrease scapular notching, but this remains controversial. We aimed here to evaluate the effect of glenoid component inferior tilt in reverse total shoulder arthroplasty (RSA) on micromotion and loss of fixation of the glenoid component by biomechanical testing. Increased inferior reaming of the glenoid for inferiorly tilted implantation of the glenoid component will decrease glenoid bone stock and compromise the fixation of RSA. The micromotions of the glenoid components attached to 14 scapulae from fresh frozen cadavers were measured and compared between neutral and 10° inferior tilts in 0.7- and 1-body weight cyclic loading tests using digital-image analysis. The incidence of bone breakage or loss of fixation was assessed in the 1-body weight fatigue-loading test. Micromotion was higher with a 10° inferior tilt than with a neutral tilt during both the 0.7-body weight (36 ± 11 μm vs. 22 ± 5 μm; P = 0.028) and 1-body weight (44 ± 16 μm vs. 28 ± 9 μm; P = 0.045) cyclic loading. The incidence of bone breakage or loss of fixation was 17% and 60% with a neutral and 10° inferior tilt, respectively. Glenoid component inferior tilt fixation in RSA may reduce primary stability and increase mechanical failure of the glenoid component, thereby reducing longevity of the prosthesis. Accordingly, we recommend careful placement of the glenoid component when an inferior tilt is used. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Complexities of One-Component Phase Diagrams

ERIC Educational Resources Information Center

Ciccioli, Andrea; Glasser, Leslie

2011-01-01

For most materials, the solid at and near the triple-point temperature is denser than the liquid with which it is in equilibrium. However, for water and certain other materials, the densities of the phases are reversed, with the solid being less dense. The profound consequences for the appearance of the "pVT" diagram of one-component materials…

Rapid detection of avian influenza virus a and subtype H5N1 by single step multiplex reverse transcription-polymerase chain reaction.

PubMed

Wei, Hui-Ling; Bai, Gui-Rong; Mweene, Aaron S; Zhou, Ying-Chun; Cong, Yan-Long; Pu, Juan; Wang, Shuai; Kida, Hiroshi; Liu, Jin-Hua

2006-06-01

Outbreaks of H5N1 highly pathogenic avian influenza (HPAI) virus caused great economic losses to the poultry industry and resulted in human deaths in Thailand and Viet Nam in 2004. Rapid typing and subtyping of H5N1 viruses, especially from clinical specimens, are desirable for taking prompt control measures to prevent the spread of the disease. Here, we developed a set of oligonucleotide primers able to detect, type and subtype H5 and N1 influenza viruses in a single step multiplex reverse transcription-polymerase chain reaction (RT-PCR). RNA was extracted from allantoic fluid or from specimens with guanidinium isothiocyanate reagent. Reverse transcription and PCR were carried out with a mixture of primers specific for influenza viruses of type A, subtype H5 and N1 in a single reaction system under identical conditions. The amplified DNA fragments were analyzed by agarose gel electrophoresis. All the H5N1 viruses tested in the study and the experimental specimens presented three specific bands by the method established here. The results presented here suggest that the method described below is rapid and specific and, therefore, could be valuable in the rapid detection of H5N1 influenza viruses in clinics.

Base Preferences in Non-Templated Nucleotide Incorporation by MMLV-Derived Reverse Transcriptases

PubMed Central

Zajac, Pawel; Islam, Saiful; Hochgerner, Hannah; Lönnerberg, Peter; Linnarsson, Sten

2013-01-01

Reverse transcriptases derived from Moloney Murine Leukemia Virus (MMLV) have an intrinsic terminal transferase activity, which causes the addition of a few non-templated nucleotides at the 3´ end of cDNA, with a preference for cytosine. This mechanism can be exploited to make the reverse transcriptase switch template from the RNA molecule to a secondary oligonucleotide during first-strand cDNA synthesis, and thereby to introduce arbitrary barcode or adaptor sequences in the cDNA. Because the mechanism is relatively efficient and occurs in a single reaction, it has recently found use in several protocols for single-cell RNA sequencing. However, the base preference of the terminal transferase activity is not known in detail, which may lead to inefficiencies in template switching when starting from tiny amounts of mRNA. Here, we used fully degenerate oligos to determine the exact base preference at the template switching site up to a distance of ten nucleotides. We found a strong preference for guanosine at the first non-templated nucleotide, with a greatly reduced bias at progressively more distant positions. Based on this result, and a number of careful optimizations, we report conditions for efficient template switching for cDNA amplification from single cells. PMID:24392002

Low temperature and high field regimes of connected kagome artificial spin ice: the role of domain wall topology.

PubMed

Zeissler, Katharina; Chadha, Megha; Lovell, Edmund; Cohen, Lesley F; Branford, Will R

2016-07-22

Artificial spin ices are frustrated magnetic nanostructures where single domain nanobars act as macrosized spins. In connected kagome artificial spin ice arrays, reversal occurs along one-dimensional chains by propagation of ferromagnetic domain walls through Y-shaped vertices. Both the vertices and the walls are complex chiral objects with well-defined topological edge-charges. At room temperature, it is established that the topological edge-charges determine the exact switching reversal path taken. However, magnetic reversal at low temperatures has received much less attention and how these chiral objects interact at reduced temperature is unknown. In this study we use magnetic force microscopy to image the magnetic reversal process at low temperatures revealing the formation of quite remarkable high energy remanence states and a change in the dynamics of the reversal process. The implication is the breakdown of the artificial spin ice regime in these connected structures at low temperatures.

Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism.

PubMed

Hounslow, Mark W

2016-08-30

Long intervals of single geomagnetic polarity (superchrons) reflect geodynamo processes, driven by core-mantle boundary interactions; however, it is not clear what initiates the start and end of superchrons, other than superchrons probably reflect lower heat flow across the core-mantle boundary compared with adjacent intervals. Here geomagnetic polarity timescales, with confidence intervals, are constructed before and following the reverse polarity Kiaman (Carboniferous-Permian) and Moyero (Ordovician) superchrons, providing a window into the geodynamo processes. Similar to the Cretaceous, asymmetry in reversal rates is seen in the Palaeozoic superchrons, but the higher reversal rates imply higher heatflow thresholds for entering the superchron state. Similar to the Cretaceous superchron, unusually long-duration chrons characterize the ∼10 Myr interval adjacent to the superchrons, indicating a transitional reversing state to the superchrons. This may relate to a weak pattern in the clustering of chron durations superimposed on the dominant random arrangement of chron durations.

Geomagnetic reversal rates following Palaeozoic superchrons have a fast restart mechanism

PubMed Central

Hounslow, Mark W.

2016-01-01

Long intervals of single geomagnetic polarity (superchrons) reflect geodynamo processes, driven by core–mantle boundary interactions; however, it is not clear what initiates the start and end of superchrons, other than superchrons probably reflect lower heat flow across the core–mantle boundary compared with adjacent intervals. Here geomagnetic polarity timescales, with confidence intervals, are constructed before and following the reverse polarity Kiaman (Carboniferous–Permian) and Moyero (Ordovician) superchrons, providing a window into the geodynamo processes. Similar to the Cretaceous, asymmetry in reversal rates is seen in the Palaeozoic superchrons, but the higher reversal rates imply higher heatflow thresholds for entering the superchron state. Similar to the Cretaceous superchron, unusually long-duration chrons characterize the ∼10 Myr interval adjacent to the superchrons, indicating a transitional reversing state to the superchrons. This may relate to a weak pattern in the clustering of chron durations superimposed on the dominant random arrangement of chron durations. PMID:27572303

A novel reversible logic gate and its systematic approach to implement cost-efficient arithmetic logic circuits using QCA.

PubMed

Ahmad, Peer Zahoor; Quadri, S M K; Ahmad, Firdous; Bahar, Ali Newaz; Wani, Ghulam Mohammad; Tantary, Shafiq Maqbool

2017-12-01

Quantum-dot cellular automata, is an extremely small size and a powerless nanotechnology. It is the possible alternative to current CMOS technology. Reversible QCA logic is the most important issue at present time to reduce power losses. This paper presents a novel reversible logic gate called the F-Gate. It is simplest in design and a powerful technique to implement reversible logic. A systematic approach has been used to implement a novel single layer reversible Full-Adder, Full-Subtractor and a Full Adder-Subtractor using the F-Gate. The proposed Full Adder-Subtractor has achieved significant improvements in terms of overall circuit parameters among the most previously cost-efficient designs that exploit the inevitable nano-level issues to perform arithmetic computing. The proposed designs have been authenticated and simulated using QCADesigner tool ver. 2.0.3.

Controlled method of reducing electrophoretic mobility of various substances

NASA Technical Reports Server (NTRS)

Vanalstine, James M. (Inventor)

1989-01-01

A method of reducing electrophoretic mobility of macromolecules, particles, cells, and the like is provided. The method comprises interacting the particles or cells with a polymer-linked affinity compound composed of: a hydrophilic neutral polymer such as polyethylene glycol, and an affinity component consisting of a hydrophobic compound such as a fatty acid ester, an immunocompound such as an antibody or active fragment thereof or simular macromolecule, or other ligands. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and the mobility reduction obtainable is up to 100 percent for particular particles and cells. The present invention is advantageous in that analytical electrophoretic separation can not be achieved for macromolecules, particles, and cells whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions. The present method is also advantageous in that it can be used in a variety of standard laboratory electrophoresis equipment.

MORE: mixed optimization for reverse engineering--an application to modeling biological networks response via sparse systems of nonlinear differential equations.

PubMed

Sambo, Francesco; de Oca, Marco A Montes; Di Camillo, Barbara; Toffolo, Gianna; Stützle, Thomas

2012-01-01

Reverse engineering is the problem of inferring the structure of a network of interactions between biological variables from a set of observations. In this paper, we propose an optimization algorithm, called MORE, for the reverse engineering of biological networks from time series data. The model inferred by MORE is a sparse system of nonlinear differential equations, complex enough to realistically describe the dynamics of a biological system. MORE tackles separately the discrete component of the problem, the determination of the biological network topology, and the continuous component of the problem, the strength of the interactions. This approach allows us both to enforce system sparsity, by globally constraining the number of edges, and to integrate a priori information about the structure of the underlying interaction network. Experimental results on simulated and real-world networks show that the mixed discrete/continuous optimization approach of MORE significantly outperforms standard continuous optimization and that MORE is competitive with the state of the art in terms of accuracy of the inferred networks.

Sleep Duration and Midday Napping with 5-Year Incidence and Reversion of Metabolic Syndrome in Middle-Aged and Older Chinese

PubMed Central

Yang, Liangle; Xu, Zengguang; He, Meian; Yang, Handong; Li, Xiulou; Min, Xinwen; Zhang, Ce; Xu, Chengwei; Angileri, Francesca; Légaré, Sébastien; Yuan, Jing; Miao, Xiaoping; Guo, Huan; Yao, Ping; Wu, Tangchun; Zhang, Xiaomin

2016-01-01

Study Objectives: Prospective evidence on the association of sleep duration and midday napping with metabolic syndrome (MetS) is limited. We aimed to examine the associations of sleep duration and midday napping with risk of incidence and reversion of MetS and its components among a middle-aged and older Chinese population. Methods: We included 14,399 subjects from the Dongfeng-Tongji (DFTJ) Cohort Study (2008–2013) who were free of coronary heart disease, stroke, and cancer at baseline. Baseline data were obtained by questionnaires and health examinations. Odds ratios (ORs) and 95% confidence interval (CI) were derived from multivariate logistic regression models. Results: After controlling for potential covariates, longer sleep duration (≥ 9 h) was associated with a higher risk of MetS incidence (OR, 1.29; 95% CI, 1.08–1.55) and lower reversion of MetS (OR, 0.80; 95% CI, 0.66–0.96) compared with sleep duration of 7 to < 8 h; whereas shorter sleep duration (< 6 h) was not related to incidence or reversion of MetS. For midday napping, subjects with longer napping (≥ 90 min) was also associated with a higher risk of MetS incidence and a lower risk of MetS reversion compared with those with napping of 1 to < 30 min (OR, 1.48; 95% CI, 1.05–2.10 and OR, 0.70; 95% CI, 0.52–0.94, respectively). Significance for incidence or reversion of certain MetS components remained in shorter and longer sleepers but disappeared across napping categories. Conclusions: Both longer sleep duration and longer midday napping were potential risk factors for MetS incidence, and concurrently exert adverse effects on MetS reversion. Citation: Yang L, Xu Z, He M, Yang H, Li X, Min X, Zhang C, Xu C, Angileri F, Légaré S, Yuan J, Miao X, Guo H, Yao P, Wu T, Zhang X. Sleep duration and midday napping with 5-year incidence and reversion of metabolic syndrome in middle-aged and older Chinese. SLEEP 2016;39(11):1911–1918. PMID:27450688

Is Stacking Intervention Components Cost-Effective? An Analysis of the Incredible Years Program

ERIC Educational Resources Information Center

Foster, E. Michael; Olchowski, Allison E.; Webster-Stratton, Carolyn H.

2007-01-01

The cost-effectiveness of delivering stacked multiple intervention components for children is compared to implementing single intervention by analyzing the Incredible Years Series program. The result suggests multiple intervention components are more cost-effective than single intervention components.

Catalytically active nanorotor reversibly self-assembled by chemical signaling within an eight-component network.

PubMed

Goswami, Abir; Pramanik, Susnata; Schmittel, Michael

2018-04-17

A catalytically active three-component nanorotor is reversibly self-assembled and disassembled by remote control. When zinc(ii) ions (2 equiv.) are added as an external chemical trigger to the mixture of transmitter [Cu(1)]+ and pre-rotor assembly [(S)·(R)], two equiv. of copper(i) ions translocate from [Cu(1)]+ to the two phenanthroline sites of [(S)·(R)]. As a result, [Zn(1)]2+ forms along with the three-component assembly [Cu2(S)(R)]2+, which is both a nanorotor (k298 = 46 kHz, ΔH‡ = 49.1 ± 0.4 kJ mol-1, ΔS‡ = 9.5 ± 1.7 J mol-1 K-1) and a catalyst for click reactions (catalysis ON: A + B→AB). Removal of zinc from the mixture reverts the translocation sequence and thus commands disassembly of the catalytically active rotor (catalysis OFF). The ON/OFF catalytic cycle was run twice in situ in the full network.

Reversal modes in FeCoNi nanowire arrays: Correlation between magnetostatic interactions and nanowires length

NASA Astrophysics Data System (ADS)

Samanifar, S.; Almasi Kashi, M.; Ramazani, A.; Alikhani, M.

2015-03-01

FeCoNi nanowire arrays (175 nm in diameter and lengths ranging from 5 to 40 μm) were fabricated into nanopores of hard-anodized aluminum oxide templates using pulsed ac electrodeposition technique. Increasing the length had no considerable effect on the composition and crystalline characteristics of Fe47Co38Ni15 nanowires (NWs). By eliminating the dendrites formed at the bottom of the pores, we report a careful investigation on the effect of magnetostatic interactions on magnetic properties and the effect of nanowire length on reversal modes. Hysteresis loop measurements indicated that increasing the length decreases coercivity and squareness values. On the other hand, first-order reversal curve measurements show a linear correlation between the magnetostatic interactions and length of NWs. Comparing reversal modes of the NWs both experimentally and theoretically using angular dependence of coercivity, we find that when L≤22 μm, a vortex domain wall mode is only occurred. When L>22 μm, a non-monotonic behavior indicates a transition from the vortex to transverse domain wall propagation. As a result, a critical length was found above which the transition between the reversal modes is occurred due the enhanced interactions. The transition angle also shifts toward a lower angle as the length increases. Moreover, with increasing length from 22 to 31 μm, the single domain structure of NWs changes to a pseudo single domain state. A multidomain-like behavior is also found for the longest NWs length.

O Electromagnetic Power Waves and Power Density Components.

NASA Astrophysics Data System (ADS)

Petzold, Donald Wayne

1980-12-01

On January 10, 1884 Lord Rayleigh presented a paper entitled "On the Transfer of Energy in the Electromagnetic Field" to the Royal Society of London. This paper had been authored by the late Fellow of Trinity College, Cambridge, Professor J. H. Poynting and in it he claimed that there was a general law for the transfer of electromagnetic energy. He argued that associated with each point in space is a quantity, that has since been called the Poynting vector, that is a measure of the rate of energy flow per unit area. His analysis was concerned with the integration of this power density vector at all points over an enclosing surface of a specific volume. The interpretation of this Poynting vector as a true measure of the local power density was viewed with great skepticism unless the vector was integrated over a closed surface, as the development of the concept required. However, within the last decade or so Shadowitz indicates that a number of prominent authors have argued that the criticism of the interpretation of Poynting's vector as a local power density vector is unjustified. The present paper is not concerned with these arguments but instead is concerned with a decomposition of Poynting's power density vector into two and only two components: one vector which has the same direction as Poynting's vector and which is called the forward power density vector, and another vector, directed opposite to the Poynting vector and called the reverse power density vector. These new local forward and reverse power density vectors will be shown to be dependent upon forward and reverse power wave vectors and these vectors in turn will be related to newly defined forward and reverse components of the electric and magnetic fields. The sum of these forward and reverse power density vectors, which is simply the original Poynting vector, is associated with the total electromagnetic energy traveling past the local point. Another vector which is the difference between the forward and reverse power density vectors and which will be shown to be associated with the total electric and magnetic field energy densities existing at a local point will also be introduced. These local forward and reverse power density vectors may be integrated over a surface to determine the forward and reverse powers and from these results problems related to maximum power transfer or efficiency of electromagnetic energy transmission in space may be studied in a manner similar to that presently being done with transmission lines, wave guides, and more recently with two port multiport lumped parameter systems. These new forward and reverse power density vectors at a point in space are analogous to the forward and revoltages or currents and power waves as used with the transmission line, waveguide, or port. These power wave vectors in space are a generalization of the power waves as developed by Penfield, Youla, and Kurokawa and used with the scattering parameters associated with transmission lines, waveguides and ports.

Orientation Dependence of Functional Properties in Heterophase Single Crystals of the Ti36.5Ni51.0Hf12.5 and Ti48.5Ni51.5 Alloys

NASA Astrophysics Data System (ADS)

Panchenko, E. Yu.; Chumlyakov, Yu. I.; Surikov, N. Yu.; Tagiltsev, A. I.; Vetoshkina, N. G.; Osipovich, K. S.; Maier, H.; Sehitoglu, H.

2016-03-01

The features of orientation dependence of stress-induced thermoelastic B2-( R)- B19'-martensitic transformations in single crystals of the Ti48.5Ni51.5 and Ni51.0Ti36.5Hf12.5 (at.%) alloys, which contain disperse particles of the Ti3Ni4 and H-phase, respectively, are revealed along with those of their shape-memory effects (SME) and superelasticity (SE). It is experimentally demonstrated that irrespective of the crystal structure of disperse particles measuring more than 100 nm, for their volume fraction f > 16% there is a weaker orientation dependence of the reversible strain in the cases of manifestation of SME and SE. In the orientations of Class I, wherein martensitic detwinning introduces a considerable contribution into transformation strain, the values of SME |ɛ SME | and SE |ɛ SE | decrease by over a factor of two compared to the theoretical lattice strain value |ɛ tr0 | for a B2- B19'-transformation and the experimental values of reversible strain for quenched TiNi crystals. In the orientations of Class 2, wherein detwinning of the martensite is suppressed as is the case in quenched single-phase single crystals, the reversible strain is maintained close to its theoretical value |ɛ tr0 |. Micromechanical models of interaction between the martensite and the disperse particles are proposed, which account for the weaker orientation dependence of |ɛ SME | and |ɛ SE | due to suppression of detwinning of the B19'-martensite crystals by the particles and a transition from a single-variant evolution of the stress-induced martensitic transformations to a multiple-variant evolution of transformations in the cases of increased size of the particles and their larger volume fractions.

Putting the past behind us: Social stress-induced urinary retention can be overcome.

PubMed

Weiss, Dana A; Butler, Stephan J; Fesi, Joanna; Long, Christopher J; Valentino, Rita J; Canning, Douglas A; Zderic, Stephen A

2015-08-01

To study the pathophysiology of dysfunctional voiding, we have previously developed a model of stress-induced voiding dysfunction. We have shown that cyclosporine A (CsA), an inhibitor of the Ca(2+)-calmodulin complex, can prevent social stress-induced urinary retention. However, treatment with cyclosporine has not had an effect on the increase in the stress peptide corticotrophin-releasing factor (CRF) in Barrington's nucleus, which is involved in the micturition pathway. We now investigate whether cyclosporine administered after stress can reverse the abnormal voiding phenotype, and whether it has effects on the bladder wall itself, or on the stress response within Barrington's nucleus. Six-week old Swiss-Webster mice were exposed to aggressor males for 1 h a day, followed by 23 h of barrier separation. In a long-term trial, 1 month of stress was followed by single-cage housing for 6 months. In a separate CsA reversal trial, mice either received CsA in drinking water or had plain drinking water during 1 month of single-cage housing during recovery. Bladder contractile function was examined on a Guth myograph. Nuclear translocation of myocyte enhancing factor (MEF)-2 and NFAT (nuclear factor of activated T cells) in the bladder was assessed using electrophoretic mobility shift assays (EMSAs). The expression of CRF was determined in Barrington's nucleus using in situ hybridization. Voiding dysfunction persisted for up to 6 months after stress exposure while mice recovered in single-cage housing. In the CsA reversal trial, voiding patterns improved when they received CsA in water during single-cage housing following stress, whereas those that underwent single-cage housing alone had persistent abnormal voiding (Fig. A). There was no difference between CRF levels in Barrington's nucleus between reversal groups (p = 0.42) (Fig. B), possibly indicating a direct effect on the bladder rather than a persistent stress effect. There were no differences in the contractility of bladder wall muscle. CsA decreased the nuclear translocation of MEF-2 and NFAT induced by stress (Fig. C,D). CsA reverses stress-induced urinary retention, but does not change the stress-induced CRF increase in Barrington's nucleus. Furthermore, bladder smooth muscle contractility is unchanged by CsA; however, there are changes in the levels of the downstream transcription factors MEF-2 and NFAT. We suspect that additional CsA responsive neural changes play a pivotal role in the abnormal voiding phenotype following social stress. Copyright © 2015 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

Synthesis of nanostructured materials by using metal-cyanide coordination polymers and their lithium storage properties

NASA Astrophysics Data System (ADS)

Nie, Ping; Shen, Laifa; Luo, Haifeng; Li, Hongsen; Xu, Guiyin; Zhang, Xiaogang

2013-10-01

Herein, we demonstrate a novel and simple two-step process for preparing LiCoO2 nanocrystals by using a Prussian blue analogue Co3[Co(CN)6]2 as a precursor. The resultant LiCoO2 nanoparticles possess single crystalline nature and good uniformity with an average size of ca. 360 nm. The unique nanostructure of LiCoO2 provides relatively shorter Li+ diffusion pathways, thus facilitating the fast kinetics of electrochemical reactions. As a consequence, high reversible capacity, excellent cycling stability and rate capability are achieved with these nanocrystals as cathodes for lithium storage. The LiCoO2 nanocrystals deliver specific capacities of 154.5, 135.8, 119, and 100.3 mA h g-1 at 0.2, 0.4, 1, and 2 C rates, respectively. Even at a high current density of 4 C, a reversible capacity of 87 mA h g-1 could be maintained. Importantly, a capacity retention of 83.4% after 100 cycles is achieved at a constant discharge rate of 1 C. Furthermore, owing to facile control of the morphology and size of Prussian blue analogues by varying process parameters, as well as the tailored design of multi-component metal-cyanide hybrid coordination polymers, with which we have successfully prepared porous Fe2O3@NixCo3-xO4 nanocubes, one of the potential anode materials for lithium-ion batteries, such a simple and scalable approach could also be applied to the synthesis of other nanomaterials for energy storage devices.Herein, we demonstrate a novel and simple two-step process for preparing LiCoO2 nanocrystals by using a Prussian blue analogue Co3[Co(CN)6]2 as a precursor. The resultant LiCoO2 nanoparticles possess single crystalline nature and good uniformity with an average size of ca. 360 nm. The unique nanostructure of LiCoO2 provides relatively shorter Li+ diffusion pathways, thus facilitating the fast kinetics of electrochemical reactions. As a consequence, high reversible capacity, excellent cycling stability and rate capability are achieved with these nanocrystals as cathodes for lithium storage. The LiCoO2 nanocrystals deliver specific capacities of 154.5, 135.8, 119, and 100.3 mA h g-1 at 0.2, 0.4, 1, and 2 C rates, respectively. Even at a high current density of 4 C, a reversible capacity of 87 mA h g-1 could be maintained. Importantly, a capacity retention of 83.4% after 100 cycles is achieved at a constant discharge rate of 1 C. Furthermore, owing to facile control of the morphology and size of Prussian blue analogues by varying process parameters, as well as the tailored design of multi-component metal-cyanide hybrid coordination polymers, with which we have successfully prepared porous Fe2O3@NixCo3-xO4 nanocubes, one of the potential anode materials for lithium-ion batteries, such a simple and scalable approach could also be applied to the synthesis of other nanomaterials for energy storage devices. Electronic supplementary information (ESI) available: Detailed experimental procedures and supplementary figures. See DOI: 10.1039/c3nr03289b

Changes of Attention during Value-Based Reversal Learning Are Tracked by N2pc and Feedback-Related Negativity

PubMed Central

Oemisch, Mariann; Watson, Marcus R.; Womelsdorf, Thilo; Schubö, Anna

2017-01-01

Previously learned reward values can have a pronounced impact, behaviorally and neurophysiologically, on the allocation of selective attention. All else constant, stimuli previously associated with a high value gain stronger attentional prioritization than stimuli previously associated with a low value. The N2pc, an ERP component indicative of attentional target selection, has been shown to reflect aspects of this prioritization, by changes of mean amplitudes closely corresponding to selective enhancement of high value target processing and suppression of high value distractor processing. What has remained unclear so far is whether the N2pc also reflects the flexible and repeated behavioral adjustments needed in a volatile task environment, in which the values of stimuli are reversed often and unannounced. Using a value-based reversal learning task, we found evidence that the N2pc amplitude flexibly and reversibly tracks value-based choices during the learning of reward associated stimulus colors. Specifically, successful learning of current value-contingencies was associated with reduced N2pc amplitudes, and this effect was more apparent for distractor processing, compared with target processing. In addition, following a value reversal the feedback related negativity(FRN), an ERP component that reflects feedback processing, was amplified and co-occurred with increased N2pc amplitudes in trials following low-value feedback. Importantly, participants that showed the greatest adjustment in N2pc amplitudes based on feedback were also the most efficient learners. These results allow further insight into how changes in attentional prioritization in an uncertain and volatile environment support flexible adjustments of behavior. PMID:29163113

Changes of Attention during Value-Based Reversal Learning Are Tracked by N2pc and Feedback-Related Negativity.

PubMed

Oemisch, Mariann; Watson, Marcus R; Womelsdorf, Thilo; Schubö, Anna

2017-01-01

Previously learned reward values can have a pronounced impact, behaviorally and neurophysiologically, on the allocation of selective attention. All else constant, stimuli previously associated with a high value gain stronger attentional prioritization than stimuli previously associated with a low value. The N2pc, an ERP component indicative of attentional target selection, has been shown to reflect aspects of this prioritization, by changes of mean amplitudes closely corresponding to selective enhancement of high value target processing and suppression of high value distractor processing. What has remained unclear so far is whether the N2pc also reflects the flexible and repeated behavioral adjustments needed in a volatile task environment, in which the values of stimuli are reversed often and unannounced. Using a value-based reversal learning task, we found evidence that the N2pc amplitude flexibly and reversibly tracks value-based choices during the learning of reward associated stimulus colors. Specifically, successful learning of current value-contingencies was associated with reduced N2pc amplitudes, and this effect was more apparent for distractor processing, compared with target processing. In addition, following a value reversal the feedback related negativity(FRN), an ERP component that reflects feedback processing, was amplified and co-occurred with increased N2pc amplitudes in trials following low-value feedback. Importantly, participants that showed the greatest adjustment in N2pc amplitudes based on feedback were also the most efficient learners. These results allow further insight into how changes in attentional prioritization in an uncertain and volatile environment support flexible adjustments of behavior.

Inversion and contrast polarity reversal affect both encoding and recognition processes of unfamiliar faces: a repetition study using ERPs.

PubMed

Itier, Roxane J; Taylor, Margot J

2002-02-01

Using ERPs in a face recognition task, we investigated whether inversion and contrast reversal, which seem to disrupt different aspects of face configuration, differentially affected encoding and memory for faces. Upright, inverted, and negative (contrast-reversed) unknown faces were either immediately repeated (0-lag) or repeated after 1 intervening face (1-lag). The encoding condition (new) consisted of the first presentation of items correctly recognized in the two repeated conditions. 0-lag faces were recognized better and faster than 1-lag faces. Inverted and negative pictures elicited longer reaction times, lower hit rates, and higher false alarm rates than upright faces. ERP analyses revealed that negative and inverted faces affected both early (encoding) and late (recognition) stages of face processing. Early components (N170, VPP) were delayed and enhanced by both inversion and contrast reversal which also affected P1 and P2 components. Amplitudes were higher for inverted faces at frontal and parietal sites from 350 to 600 ms. Priming effects were seen at encoding stages, revealed by shorter latencies and smaller amplitudes of N170 for repeated stimuli, which did not differ depending on face type. Repeated faces yielded more positive amplitudes than new faces from 250 to 450 ms frontally and from 400 to 600 ms parietally. However, ERP differences revealed that the magnitude of this repetition effect was smaller for negative and inverted than upright faces at 0-lag but not at 1-lag condition. Thus, face encoding and recognition processes were affected by inversion and contrast-reversal differently.

Sensing resonant objects in the presence of noise and clutter using iterative, single-channel acoustic time reversal

NASA Astrophysics Data System (ADS)

Waters, Zachary John

The presence of noise and coherent returns from clutter often confounds efforts to acoustically detect and identify target objects buried in inhomogeneous media. Using iterative time reversal with a single channel transducer, returns from resonant targets are enhanced, yielding convergence to a narrowband waveform characteristic of the dominant mode in a target's elastic scattering response. The procedure consists of exciting the target with a broadband acoustic pulse, sampling the return using a finite time window, reversing the signal in time, and using this reversed signal as the source waveform for the next interrogation. Scaled laboratory experiments (0.4-2 MHz) are performed employing a piston transducer and spherical targets suspended in the free field and buried in a sediment phantom. In conjunction with numerical simulations, these experiments provide an inexpensive and highly controlled means with which to examine the efficacy of the technique. Signal-to-noise enhancement of target echoes is demonstrated. The methodology reported provides a means to extract both time and frequency information for surface waves that propagate on an elastic target. Methods developed in the laboratory are then applied in medium scale (20-200 kHz) pond experiments for the detection of a steel shell buried in sandy sediment.

Novel Designs of Quantum Reversible Counters

NASA Astrophysics Data System (ADS)

Qi, Xuemei; Zhu, Haihong; Chen, Fulong; Zhu, Junru; Zhang, Ziyang

2016-11-01

Reversible logic, as an interesting and important issue, has been widely used in designing combinational and sequential circuits for low-power and high-speed computation. Though a significant number of works have been done on reversible combinational logic, the realization of reversible sequential circuit is still at premature stage. Reversible counter is not only an important part of the sequential circuit but also an essential part of the quantum circuit system. In this paper, we designed two kinds of novel reversible counters. In order to construct counter, the innovative reversible T Flip-flop Gate (TFG), T Flip-flop block (T_FF) and JK flip-flop block (JK_FF) are proposed. Based on the above blocks and some existing reversible gates, the 4-bit binary-coded decimal (BCD) counter and controlled Up/Down synchronous counter are designed. With the help of Verilog hardware description language (Verilog HDL), these counters above have been modeled and confirmed. According to the simulation results, our circuits' logic structures are validated. Compared to the existing ones in terms of quantum cost (QC), delay (DL) and garbage outputs (GBO), it can be concluded that our designs perform better than the others. There is no doubt that they can be used as a kind of important storage components to be applied in future low-power computing systems.

Velocity and pressure characteristics of a model SSME high pressure fuel turbopump

NASA Technical Reports Server (NTRS)

Tse, D. G-N.; Sabnis, J. S.; Mcdonald, H.

1991-01-01

Under the present effort an experiment rig has been constructed, an instrumentation package developed and a series of mean and rms velocity and pressure measurements made in a turbopump which modelled the first stage of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump. The rig was designed so as to allow initial experiments with a single configuration consisting of a bell-mouth inlet, a flight impeller, a vaneless diffuser and a volute. Allowance was made for components such as inlet guide vanes, exit guide vanes, downstream pumps, etc. to be added in future experiments. This flexibility will provide a clear baseline set of experiments and allow evaluation in later experiments of the effect of adding specific components upon the pump performance properties. The rotational speed of the impeller was varied between 4260 and 7680 rpm which covered the range of scaled SSME rotation speeds when due allowance is made for the differing stagnation temperature, model to full scale. The results at the inlet obtained with rotational speeds of 4260, 6084 and 7680 rpm showed that the axial velocity at the bell-mouth inlet remained roughly constant at 2.2 of the bulk velocity at the exit of the turbopump near the center of the inlet, but it decreased rapidly with increasing radius at all three speeds. Reverse flow occurred at a radius greater than 0.9 R for all three speeds and the maximum negative velocity reduced from 1.3 of the bulk velocity at the exit of the turbopump at 4260 rpm to 0.35 at 7680 rpm, suggesting that operating at a speed closer to the design condition of 8700 rpm improved the inlet characteristics. The reverse flow caused positive prerotation at the impeller inlet which was negligibly small near the center but reached 0.7 of the impeller speed at the outer annulus. The results in the diffuser and the volute obtained at 7680 rpm show that the hub and shroud walls of the diffuser were characterized by regions of transient reverse flow with negative revolution-averaged velocity of 8 percent of the maximum forward revolution-averaged velocity at the center of the diffuser passage near the shroud wall.

Combining features from ERP components in single-trial EEG for discriminating four-category visual objects.

PubMed

Wang, Changming; Xiong, Shi; Hu, Xiaoping; Yao, Li; Zhang, Jiacai

2012-10-01

Categorization of images containing visual objects can be successfully recognized using single-trial electroencephalograph (EEG) measured when subjects view images. Previous studies have shown that task-related information contained in event-related potential (ERP) components could discriminate two or three categories of object images. In this study, we investigated whether four categories of objects (human faces, buildings, cats and cars) could be mutually discriminated using single-trial EEG data. Here, the EEG waveforms acquired while subjects were viewing four categories of object images were segmented into several ERP components (P1, N1, P2a and P2b), and then Fisher linear discriminant analysis (Fisher-LDA) was used to classify EEG features extracted from ERP components. Firstly, we compared the classification results using features from single ERP components, and identified that the N1 component achieved the highest classification accuracies. Secondly, we discriminated four categories of objects using combining features from multiple ERP components, and showed that combination of ERP components improved four-category classification accuracies by utilizing the complementarity of discriminative information in ERP components. These findings confirmed that four categories of object images could be discriminated with single-trial EEG and could direct us to select effective EEG features for classifying visual objects.

Paleomagnetism and paleosecular variation from the late Miocene to recent lavas of Mauritius

NASA Astrophysics Data System (ADS)

Doubrovine, Pavel V.; Torsvik, Trond H.; Domeier, Mathew

2017-04-01

We present new paleomagnetic data from the late Miocene to recent lavas of the island of Mauritius in the southwestern Indian Ocean (20.3˚ S, 57.6˚ E). The island is a shield volcano that has formed over the Reunion hotspot and is composed of three temporally-distinct series of basaltic lavas: the Older Series (4.7-8.9 Ma), the Intermediate Series (1.7-3.5 Ma) and the Younger Series (0-1 Ma). Oriented core specimens were collected from 36 sampling sites covering all three lava series. Rock magnetic analyses indicate that the remanence carriers in these basalts are pseudo-single-domain titanomagnetites with variable degrees of high-temperature oxidation. Nearly half of the sites showed pervasive magnetic overprints imparted by lightning strikes. Nonetheless, in almost all cases (35 sites), we were able to isolate the characteristic (primary) remanence directions through detailed thermal and alternating field demagnetization experiments, using the principal component analysis of demagnetization data and the analysis of remagnetization circles. Both normal and reverse polarity directions were observed, with the mean direction of the reversely-magnetized lavas (15 sites, D = 189.2˚ , I = 44˚ , α95 = 5.3˚ ) being steeper than and ca. 9˚ of antiparallel from the mean direction of the normal-polarity flows (20 sites, D = 1.1˚ , I = -37.3˚ , α95 = 6.9˚ ). The mean normal and reverse directions yield a negative reversal test that is just significant at the 5% probability level (P = 4.5%). However, when our new data set is combined with previously published paleomagnetic results from Mauritius, the difference between the normal mean direction and the antipode of the reverse mean is not significant at the 5% level, yielding a positive reversal test. The paleomagnetic pole corresponding to the combined polarity data set excluding transitional directions (86.7˚ N, 186.2˚ E, A95 = 3.5˚ , n = 32) is slightly far-sided, but the difference between its position and the geographic pole is not statistically significant. The estimates of paleosecular variation (PSV) and inclination anomaly (Sb = 11˚ , ΔI = -2˚ ) are in good agreement with the results of PSV studies of recent lavas erupted at low latitudes. The implications of our new results for the structure of time-averaged geomagnetic field and the latitude dependence of PSV will be discussed.

The Role of Self-Organized Criticality in the Substorm Phenomenon and its Relation to Localized Reconnection in the Magnetospheric Plasma Sheet

NASA Technical Reports Server (NTRS)

Klimas, Alex J.; Valdivia, J. A.; Vassiliadis, D.; Baker, D. N.; Hesse, M.; Takalo, J.

1999-01-01

Evidence is presented that suggests there is a significant self-organized criticality (SOC) component in the dynamics of substorms in the magnetosphere. Observations of BBFs, fast flows, localized dipolarizations, plasma turbulence, etc. are taken to show that multiple localized reconnection sites provide the basic avalanche phenomenon in the establishment of SOC in the plasma sheet. First results are presented from a continuing plasma physical study of this avalanche process. A one-dimensional resistive MHD model of a magnetic field reversal is discussed. Resistivity, in this model, is self-consistently generated in response to the excitation of an idealized current-driven instability. When forced by convection of magnetic flux into the field reversal region, the model yields rapid magnetic field annihilation through a dynamic behavior that is shown to exhibit many of the characteristics of SOC. Over a large range of forcing strengths, the annihilation rate is shown to self-adjust to balance the rate at which flux is convected into the reversal region. Several analogies to magnetotail dynamics are discussed: (1) It is shown that the presence of a localized criticality in the model produces a remarkable stability in the global configuration of the field reversal while simultaneously exciting extraordinarily dynamic internal evolution. (2) Under steady forcing, it is shown that a loading-unloading cycle may arise that, as a consequence of the global stability, is quasi-periodic and, therefore, predictable despite the presence of internal turbulence in the field distribution. Indeed, it is shown that the global loading-unloading cycle is a consequence of the internal turbulence. (3) It is shown that, under steady, strong forcing the loading-unloading cycle vanishes. Instead, a recovery from a single unloading persists indefinitely. The field reversal is globally very steady while internally it is very dynamic as field annihilation goes on at the rate necessary to match the strong forcing. From this result we speculate that steady magnetospheric convection events result when the plasma sheet has been driven close to criticality over an extended spatial domain. During these events, we would expect to find localized reconnection sites distributed over the spatial domain of near criticality and we would expect to find plasma sheet transport in that domain to be closely related to that of BBF and fast flow events.

Negative-ion formation in the explosives RDX, PETN, and TNT by using the reversal electron attachment detection technique

NASA Technical Reports Server (NTRS)

Boumsellek, S.; Alajajian, S. H.; Chutjian, A.

1992-01-01

First results of a beam-beam, single-collision study of negative-ion mass spectra produced by attachment of zero-energy electrons to the molecules of the explosives RDX, PETN, and TNT are presented. The technique used is reversal electron attachment detection (READ) wherein the zero-energy electrons are produced by focusing an intense electron beam into a shaped electrostatic field which reverses the trajectory of electrons. The target beam is introduced at the reversal point, and attachment occurs because the electrons have essentially zero longitudinal and radial velocity. The READ technique is used to obtain the 'signature' of molecular ion formation and/or fragmentation for each explosive. Present data are compared with results from atmospheric-pressure ionization and negative-ion chemical ionization methods.

High geomagnetic intensity during the mid-Cretaceous from Thellier analyses of single plagioclase crystals.

PubMed

Tarduno, J A; Cottrell, R D; Smirnov, A V

2001-03-02

Recent numerical simulations have yielded the most efficient geodynamo, having the largest dipole intensity when reversal frequency is low. Reliable paleointensity data are limited but heretofore have suggested that reversal frequency and paleointensity are decoupled. We report data from 56 Thellier-Thellier experiments on plagioclase crystals separated from basalts of the Rajmahal Traps (113 to 116 million years old) of India that formed during the Cretaceous Normal Polarity Superchron. These data suggest a time-averaged paleomagnetic dipole moment of 12.5 +/- 1.4 x 10(22) amperes per square meter, three times greater than mean Cenozoic and Early Cretaceous-Late Jurassic dipole moments when geomagnetic reversals were frequent. This result supports a correlation between intervals of low reversal frequency and high geomagnetic field strength.

Recoil hysteresis of Sm -Co/Fe exchange-spring bilayers

NASA Astrophysics Data System (ADS)

Kang, K.; Lewis, L. H.; Jiang, J. S.; Bader, S. D.

2005-12-01

The exchange-spring behavior found in Sm-Co (20nm)/Fe epitaxial bilayer films was investigated by analyzing major hysteresis and recoil curves as a function of anneal conditions. The hard layer consists of nanocrystalline intermetallic Sm-Co hexagonal phases (majority phase Sm2Co7 with SmCo3 and SmCo5). Recoil curves, obtained from the successive removal to remanence and reapplication of an increasingly negative field from the major demagnetization curve, reveal the reversible and irreversible components of the magnetization. The Sm-Co thickness was fixed at 20nm while the Fe thicknesses of 10 and 20nm were studied, with ex situ annealing carried out in evacuated, sealed silica tubes at different temperatures. The peak in the recoil curve area is associated with the coercivity of the hard phase. The development of the soft component magnetization is revealed by the departure of the recoil area from zero with application of a reverse field. These two features together confirm that annealing stabilizes the 10nm Fe bilayer sample against local magnetic reversal while it weakens the 20nm bilayer sample. Furthermore, in both its as-deposited and annealed states the Sm -Co/Fe bilayer of 10nm Fe thickness always displays a higher exchange field and smaller recoil loop areas than the bilayer of 20nm Fe thickness, consistent with a stronger exchange response and more reversible magnetization in the former.

Nanoscale Control over the Mixing Behavior of Surface-Confined Bicomponent Supramolecular Networks Using an Oriented External Electric Field

PubMed Central

2017-01-01

Strong electric fields are known to influence the properties of molecules as well as materials. Here we show that by changing the orientation of an externally applied electric field, one can locally control the mixing behavior of two molecules physisorbed on a solid surface. Whether the starting two-component network evolves into an ordered two-dimensional (2D) cocrystal, yields an amorphous network where the two components phase separate, or shows preferential adsorption of only one component depends on the solution stoichiometry. The experiments are carried out by changing the orientation of the strong electric field that exists between the tip of a scanning tunneling microscope and a solid substrate. The structure of the two-component network typically changes from open porous at negative substrate bias to relatively compact when the polarity of the applied bias is reversed. The electric-field-induced mixing behavior is reversible, and the supramolecular system exhibits excellent stability and good response efficiency. When molecular guests are adsorbed in the porous networks, the field-induced switching behavior was found to be completely different. Plausible reasons behind the field-induced mixing behavior are discussed. PMID:29112378

Continuum analysis of the nucleus growth of reverse domains in large ferroelectric crystals

NASA Astrophysics Data System (ADS)

Neumeister, Peter; Balke, Herbert; Lupascu, Doru C.

2009-04-01

Polarization reversal in ferroelectrics arises due to domain nucleation and domain wall motion. The nucleation of reverse domains at crystal boundaries is the fundamental initiation process observed in single crystals. The classical continuum approach by Landauer determines an insurmountable energy barrier to extrinsic domain nucleation. We rediscuss the continuum approach. Predetermined surface states are found to be a misleading concept. Alternate energy contributions, for example, due to a dead layer or due to charge injection as well as reduced domain wall energy and anisotropy of domain wall energy, have to be included into a convincing picture of domain nucleation.

A novel prediction method about single components of analog circuits based on complex field modeling.

PubMed

Zhou, Jingyu; Tian, Shulin; Yang, Chenglin

2014-01-01

Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator) calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits' single components. At last, it uses particle filter (PF) to update parameters for the model and predicts remaining useful performance (RUP) of analog circuits' single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments.

Reversible and Irreversible Time-Dependent Behavior of GRCop-84

NASA Technical Reports Server (NTRS)

Lerch, Bradley A.; Arnold, Steven M.; Ellis, David L.

2017-01-01

A series of mechanical tests were conducted on a high-conductivity copper alloy, GRCop-84, in order to understand the time dependent response of this material. Tensile, creep, and stress relaxation tests were performed over a wide range of temperatures, strain rates, and stress levels to excite various amounts of time-dependent behavior. At low applied stresses the deformation behavior was found to be fully reversible. Above a certain stress, termed the viscoelastic threshold, irreversible deformation was observed. At these higher stresses the deformation was observed to be viscoplastic. Both reversible and irreversible regions contained time dependent deformation. These experimental data are documented to enable characterization of constitutive models to aid in design of high temperature components.

DevS, a heme-containing two-component oxygen sensor of Mycobacterium tuberculosis.

PubMed

Ioanoviciu, Alexandra; Yukl, Erik T; Moënne-Loccoz, Pierre; de Montellano, Paul R Ortiz

2007-04-10

Mycobacterium tuberculosis can exist in the actively growing state of the overt disease or in a latent quiescent state that can be induced, among other things, by anaerobiosis. Eradication of the latent state is particularly difficult with the available drugs and requires prolonged treatment. DevS is a member of the DevS-DevR two-component regulatory system that is thought to mediate the cellular response to anaerobiosis. Here we report the cloning, expression, and initial characterization of a truncated version of DevS (DevS642) containing only the N-terminal GAF sensor domain (GAF-A) and of the full-length protein DevS. The DevS truncated construct quantitatively binds heme in a 1:1 stoichiometry, and the complex of the protein with ferrous heme reversibly binds O2, NO, and CO. UV-vis and resonance Raman spectroscopy of the wild-type protein and the H149A mutant confirm that His149 is the proximal ligand to the heme iron atom. While the heme-CO complex is present as two conformers in the GAF-A domain, a single set of [Fe-C-O] vibrations is observed with the full-length protein, suggesting that interactions between domains within DevS influence the distal pocket environment of the heme in the GAF-A domain.

Hydrosoluble Cu(i)-DAPTA complexes: synthesis, characterization, luminescence thermochromism and catalytic activity for microwave-assisted three-component azide-alkyne cycloaddition click reaction.

PubMed

Mahmoud, Abdallah G; Guedes da Silva, M Fátima C; Sokolnicki, Jerzy; Smoleński, Piotr; Pombeiro, Armando J L

2018-05-16

New hydrosoluble and air-stable Cu(i) halide compounds, viz. [CuX(DAPTA)3] (1) and (2), and [Cu(μ-X)(DAPTA)2]2 (3) and (4) (X = Br or I, in this order), have been prepared by reacting Cu(i) halide (i.e., bromide or iodide) with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) under mild conditions. They represent the first examples of Cu(i) halide complexes bearing the DAPTA ligand, which have been fully characterized by elemental analysis, IR, 1H, 13C{1H} and 31P{1H} NMR spectroscopies, ESI-MS+ and, for 4, also by single-crystal X-ray diffraction (SCXRD) analyses. Complexes 1-4 are efficient catalysts for the one-pot microwave assisted three-component (terminal alkyne, organic halide and NaN3) Huisgen cycloaddition reaction in aqueous media to afford the corresponding disubstituted triazoles. The catalysis proceeds with a broad alkyne substrate scope and according to "click rules". Photophysical studies of compound 4 showed an unusual reversible thermochromic behaviour exhibiting a blue emission at 298 K due to the halide-to-ligand charge transfer (3XLCT) and a red emission at 77 K because of the {Cu2I2} unit.

Ultrafast Microscopy of Spin-Momentum-Locked Surface Plasmon Polaritons.

PubMed

Dai, Yanan; Dąbrowski, Maciej; Apkarian, Vartkess A; Petek, Hrvoje

2018-06-26

Using two-photon photoemission electron microscopy (2P-PEEM) we image the polarization dependence of coupling and propagation of surface plasmon polaritons (SPPs) launched from edges of a triangular, micrometer size, single-crystalline Ag crystal by linearly or circularly polarized light. 2P-PEEM records interferences between the optical excitation field and SPPs it creates with nanofemto space-time resolution. Both the linearly and circularly polarized femtosecond light pulses excite spatially asymmetric 2PP yield distributions, which are imaged. We attribute the asymmetry for linearly polarized light to the relative alignments of the laser polarization and triangle edges, which affect the efficiency of excitation of the longitudinal component of the SPP field. For circular polarization, the asymmetry is caused by matching of the spin angular momenta (SAM) of light and the transverse SAM of SPPs. Moreover, we show that the interference patterns recorded in the 2P-PEEM images are cast by phase shifts and amplitudes for coupling of light into the longitudinal and transverse components of SPP fields. While the interference patterns depend on the excitation polarization, nanofemto movies show that the phase and group velocities of SPPs are independent of SAM of light in time-reversal invariant media. Simulations of the wave interference reproduce the polarization and spin-dependent coupling of optical pulses into SPPs.

Using Modeling and Simulation to Complement Testing for Increased Understanding of Weapon Subassembly Response.

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

Wong, Michael K.; Davidson, Megan

As part of Sandia’s nuclear deterrence mission, the B61-12 Life Extension Program (LEP) aims to modernize the aging weapon system. Modernization requires requalification and Sandia is using high performance computing to perform advanced computational simulations to better understand, evaluate, and verify weapon system performance in conjunction with limited physical testing. The Nose Bomb Subassembly (NBSA) of the B61-12 is responsible for producing a fuzing signal upon ground impact. The fuzing signal is dependent upon electromechanical impact sensors producing valid electrical fuzing signals at impact. Computer generated models were used to assess the timing between the impact sensor’s response to themore » deceleration of impact and damage to major components and system subassemblies. The modeling and simulation team worked alongside the physical test team to design a large-scale reverse ballistic test to not only assess system performance, but to also validate their computational models. The reverse ballistic test conducted at Sandia’s sled test facility sent a rocket sled with a representative target into a stationary B61-12 (NBSA) to characterize the nose crush and functional response of NBSA components. Data obtained from data recorders and high-speed photometrics were integrated with previously generated computer models in order to refine and validate the model’s ability to reliably simulate real-world effects. Large-scale tests are impractical to conduct for every single impact scenario. By creating reliable computer models, we can perform simulations that identify trends and produce estimates of outcomes over the entire range of required impact conditions. Sandia’s HPCs enable geometric resolution that was unachievable before, allowing for more fidelity and detail, and creating simulations that can provide insight to support evaluation of requirements and performance margins. As computing resources continue to improve, researchers at Sandia are hoping to improve these simulations so they provide increasingly credible analysis of the system response and performance over the full range of conditions.« less

Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation

PubMed Central

Sreenivasachary, Nampally; Lehn, Jean-Marie

2005-01-01

The guanosine hydrazide 1 yields a stable supramolecular hydrogel based on the formation of a guanine quartet (G-quartet) in presence of metal cations. The effect of various parameters (concentration, nature of metal ion, and temperature) on the properties of this gel has been studied. Proton NMR spectroscopy is shown to allow a molecular characterization of the gelation process. Hydrazide 1 and its assemblies can be reversibly decorated by acylhydrazone formation with various aldehydes, resulting in formation of highly viscous dynamic hydrogels. When a mixture of aldehydes is used, the dynamic system selects the aldehyde that leads to the most stable gel. Mixing hydrazides 1, 9 and aldehydes 6, 8 in 1:1:1:1 ratio generated a constitutional dynamic library containing the four acylhydrazone derivatives A, B, C, and D. The library constitution displayed preferential formation of the acylhydrazone B that yields the strongest gel. Thus, gelation redirects the acylhydrazone distribution in the dynamic library as guanosine hydrazide 1 scavenges preferentially aldehyde 8, under the pressure of gelation because of the collective interactions in the assemblies of G-quartets B, despite the strong preference of the competing hydrazide 9 for 8. Gel formation and component selection are thermoreversible. The process amounts to gelation-driven self-organization with component selection and amplification in constitutional dynamic hydrogels based on G-quartet formation and reversible covalent connections. The observed self-organization and component selection occur by means of a multilevel self-assembly involving three dynamic processes, two of supramolecular and one of reversible covalent nature. They extend constitutional dynamic chemistry to phase-organization and phase-transition events. PMID:15840720

Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation.

PubMed

Sreenivasachary, Nampally; Lehn, Jean-Marie

2005-04-26

The guanosine hydrazide 1 yields a stable supramolecular hydrogel based on the formation of a guanine quartet (G-quartet) in presence of metal cations. The effect of various parameters (concentration, nature of metal ion, and temperature) on the properties of this gel has been studied. Proton NMR spectroscopy is shown to allow a molecular characterization of the gelation process. Hydrazide 1 and its assemblies can be reversibly decorated by acylhydrazone formation with various aldehydes, resulting in formation of highly viscous dynamic hydrogels. When a mixture of aldehydes is used, the dynamic system selects the aldehyde that leads to the most stable gel. Mixing hydrazides 1, 9 and aldehydes 6, 8 in 1:1:1:1 ratio generated a constitutional dynamic library containing the four acylhydrazone derivatives A, B, C, and D. The library constitution displayed preferential formation of the acylhydrazone B that yields the strongest gel. Thus, gelation redirects the acylhydrazone distribution in the dynamic library as guanosine hydrazide 1 scavenges preferentially aldehyde 8, under the pressure of gelation because of the collective interactions in the assemblies of G-quartets B, despite the strong preference of the competing hydrazide 9 for 8. Gel formation and component selection are thermoreversible. The process amounts to gelation-driven self-organization with component selection and amplification in constitutional dynamic hydrogels based on G-quartet formation and reversible covalent connections. The observed self-organization and component selection occur by means of a multilevel self-assembly involving three dynamic processes, two of supramolecular and one of reversible covalent nature. They extend constitutional dynamic chemistry to phase-organization and phase-transition events.

Effects of Pentobarbital on Respiratory Functional Dynamics in Chronically Instrumented Guinea Pigs

DTIC Science & Technology

1991-01-01

inferior cerebellar peduncle; 10, inferior olive; LRN. lateral reticular nu- cleus; NSTTN. nucleus spinal tract of the trigeminal nerve ; STTN, spinal tract...reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP 06 15 sodium pentobarbital; respiration; chronic single unit 06 04 recording...diaphragmatic EMG; guinea pigs 19. ABSTRACT (Continue on reverse if necessary and identify by block number) CHANG. F.-C. T. Effects of pentobarhital

Novel Structure of Ty3 Reverse Transcriptase | Center for Cancer Research

Cancer.gov

Retrotransposons are mobile genetic elements that self amplify via a single-stranded RNA intermediate, which is converted to double-stranded DNA by an encoded reverse transcriptase (RT) with both DNA polymerase (pol) and ribonuclease H (RNase) activities. Categorized by whether they contain flanking long terminal repeat (LTR) sequences, retrotransposons play a critical role in the architecture of eukaryotic genomes and are the evolutionary origin of retroviruses, including human immunodeficiency virus (HIV).

Design Methodology for Bonded-Bolted Composite Joints. Volume I. Analysis Derivations and Illustrative Solutions

DTIC Science & Technology

1982-02-01

EXPERIMENTAL EVIDENCE ...... ....... ....... ....... ... 27 2.6 LOAD REDISTRIBUTION DUE TO DISBONDS IN ADHESIVE IN STEPPED-LAP JOINTS...SINGLE FASTENER " . ;39 3.4 LOAD SHARING BETWEEN MULTIRUW FASTENERS.."."..-.."." ൴ 3.5 FAILURE CRITERIA AT FASTENER HOLES . . ... 3.6 EXPERIMENTAL ...PLASTIC C. PERFECTLY ELASTIC THROUGHOUT A. ULL PLSTC SEAR TRS•WITHOUT $1IGN REVERSAL WITHOUT S:IG13 REVERSAL IOR FULLY NEGATIVE QUIVALENT ) (OR FULLY

Profiling of tryptophan-related plasma indoles in patients with carcinoid tumors by automated, on-line, solid-phase extraction and HPLC with fluorescence detection.

PubMed

Kema, I P; Meijer, W G; Meiborg, G; Ooms, B; Willemse, P H; de Vries, E G

2001-10-01

Profiling of the plasma indoles tryptophan, 5-hydroxytryptophan (5-HTP), serotonin, and 5-hydroxyindoleacetic acid (5-HIAA) is useful in the diagnosis and follow-up of patients with carcinoid tumors. We describe an automated method for the profiling of these indoles in protein-containing matrices as well as the plasma indole concentrations in healthy controls and patients with carcinoid tumors. Plasma, cerebrospinal fluid, and tissue homogenates were prepurified by automated on-line solid-phase extraction (SPE) in Hysphere Resin SH SPE cartridges containing strong hydrophobic polystyrene resin. Analytes were eluted from the SPE cartridge by column switching. Subsequent separation and detection were performed by reversed-phase HPLC combined with fluorometric detection in a total cycle time of 20 min. We obtained samples from 14 healthy controls and 17 patients with metastasized midgut carcinoid tumors for plasma indole analysis. In the patient group, urinary excretion of 5-HIAA and serotonin was compared with concentrations of plasma indoles. Within- and between-series CVs for indoles in platelet-rich plasma were 0.6-6.2% and 3.7-12%, respectively. Results for platelet-rich plasma serotonin compared favorably with those obtained by single-component analysis. Plasma 5-HIAA, but not 5-HTP was detectable in 8 of 17 patients with carcinoid tumors. In the patient group, platelet-rich plasma total tryptophan correlated negatively with platelet-rich plasma serotonin (P = 0.021; r = -0.56), urinary 5-HIAA (P = 0.003; r = -0.68), and urinary serotonin (P <0.0001; r = -0.80). The present chromatographic approach reduces analytical variation and time needed for analysis and gives more detailed information about metabolic deviations in indole metabolism than do manual, single-component analyses.

Structural alterations in a component of cytochrome c oxidase and molecular evolution of pathogenic Neisseria in humans.

PubMed

Aspholm, Marina; Aas, Finn Erik; Harrison, Odile B; Quinn, Diana; Vik, Ashild; Viburiene, Raimonda; Tønjum, Tone; Moir, James; Maiden, Martin C J; Koomey, Michael

2010-08-19

Three closely related bacterial species within the genus Neisseria are of importance to human disease and health. Neisseria meningitidis is a major cause of meningitis, while Neisseria gonorrhoeae is the agent of the sexually transmitted disease gonorrhea and Neisseria lactamica is a common, harmless commensal of children. Comparative genomics have yet to yield clear insights into which factors dictate the unique host-parasite relationships exhibited by each since, as a group, they display remarkable conservation at the levels of nucleotide sequence, gene content and synteny. Here, we discovered two rare alterations in the gene encoding the CcoP protein component of cytochrome cbb(3) oxidase that are phylogenetically informative. One is a single nucleotide polymorphism resulting in CcoP truncation that acts as a molecular signature for the species N. meningitidis. We go on to show that the ancestral ccoP gene arose by a unique gene duplication and fusion event and is specifically and completely distributed within species of the genus Neisseria. Surprisingly, we found that strains engineered to express either of the two CcoP forms conditionally differed in their capacity to support nitrite-dependent, microaerobic growth mediated by NirK, a nitrite reductase. Thus, we propose that changes in CcoP domain architecture and ensuing alterations in function are key traits in successive, adaptive radiations within these metapopulations. These findings provide a dramatic example of how rare changes in core metabolic proteins can be connected to significant macroevolutionary shifts. They also show how evolutionary change at the molecular level can be linked to metabolic innovation and its reversal as well as demonstrating how genotype can be used to infer alterations of the fitness landscape within a single host.

Combination of HPLC-MS and QAMS as a new analytical approach for determination of saponins in ginseng containing products.

PubMed

Stavrianidi, Andrey; Stekolshchikova, Elena; Porotova, Anna; Rodin, Igor; Shpigun, Oleg

2017-01-05

Conventional liquid chromatographic methods coupled with ultraviolet detection with low-wavelength range are lacking selectivity and sensitivity to determine both polar and less polar ginsenosides. Also the lack of standard substances for such quality control methods is leading to development of the approaches using single standard for quantitative analysis of multi-component system (QAMS). The objective of present study was to establish and compare for the first time liquid chromatography-ultraviolet detection and liquid chromatography-mass spectrometry QAMS methods for the simultaneous determination of protopanaxatriol-type and protopanaxadiol-type ginsenosides in a variety of ginseng products. Sixteen polar and less polar ginsenosides were separated on a reversed-phase C18-column (150mm×2.0mm, 2.2μm) with a mobile phase consisting of 0.1% formic acid in water and acetonitrile. Components were then detected by means of ultraviolet and mass spectrometry detection. Characteristic sapogenin fragmentation signals with m/z 423 and 425 for two major groups of ginseng saponins allowed their simultaneous determination in a single chromatographic run, while the use of ultraviolet detection tends to give overvalued results. Structural correlation between the relative response factors and saponin structure was demonstrated. The method was linear (R 2 >0.999) and sensitive (LODs, 0.01-0.03mg/mL) within the concentration range tested. Concentrations of individual ginsenosides and several quality control parameters were determined in ginseng root extracts and commercial ginseng products of different types (root slices, tablets and tea samples), and results showed that ginsenoside content can be successfully measured by means of QAMS approach. Copyright © 2016 Elsevier B.V. All rights reserved.

Not spreading in reverse: The dewetting of a liquid film into a single drop

PubMed Central

Edwards, Andrew M. J.; Ledesma-Aguilar, Rodrigo; Newton, Michael I.; Brown, Carl V.; McHale, Glen

2016-01-01

Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet—a barrier that does not exist for the reverse wetting process of a droplet spreading into a film. We report the dewetting of a dielectrophoresis-induced film into a single equilibrium droplet. The emergent picture of the full dewetting dynamics is of an initial regime, where a liquid rim recedes at constant speed and constant dynamic contact angle, followed by a relatively short exponential relaxation of a spherical cap shape. This sharply contrasts with the reverse wetting process, where a spreading droplet follows a smooth sequence of spherical cap shapes. Complementary numerical simulations and a hydrodynamic model reveal a local dewetting mechanism driven by the equilibrium contact angle, where contact line slip dominates the dewetting dynamics. Our conclusions can be used to understand a wide variety of processes involving liquid dewetting, such as drop rebound, condensation, and evaporation. In overcoming the barrier to studying single film-to-droplet dewetting, our results provide new approaches to fluid manipulation and uses of dewetting, such as inducing films of prescribed initial shapes and slip-controlled liquid retraction. PMID:27704042

Not spreading in reverse: The dewetting of a liquid film into a single drop.

PubMed

Edwards, Andrew M J; Ledesma-Aguilar, Rodrigo; Newton, Michael I; Brown, Carl V; McHale, Glen

2016-09-01

Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet-a barrier that does not exist for the reverse wetting process of a droplet spreading into a film. We report the dewetting of a dielectrophoresis-induced film into a single equilibrium droplet. The emergent picture of the full dewetting dynamics is of an initial regime, where a liquid rim recedes at constant speed and constant dynamic contact angle, followed by a relatively short exponential relaxation of a spherical cap shape. This sharply contrasts with the reverse wetting process, where a spreading droplet follows a smooth sequence of spherical cap shapes. Complementary numerical simulations and a hydrodynamic model reveal a local dewetting mechanism driven by the equilibrium contact angle, where contact line slip dominates the dewetting dynamics. Our conclusions can be used to understand a wide variety of processes involving liquid dewetting, such as drop rebound, condensation, and evaporation. In overcoming the barrier to studying single film-to-droplet dewetting, our results provide new approaches to fluid manipulation and uses of dewetting, such as inducing films of prescribed initial shapes and slip-controlled liquid retraction.

Chiral liquid phase of simple quantum magnets

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

Wang, Zhentao; Feiguin, Adrian E.; Zhu, Wei

2017-11-07

We study a T=0 quantum phase transition between a quantum paramagnetic state and a magnetically ordered state for a spin S=1 XXZ Heisenberg antiferromagnet on a two-dimensional triangular lattice. The transition is induced by an easy-plane single-ion anisotropy D. At the mean-field level, the system undergoes a direct transition at a critical D=D c between a paramagnetic state at D>D c and an ordered state with broken U(1) symmetry at Dc. We show that beyond mean field the phase diagram is very different and includes an intermediate, partially ordered chiral liquid phase. Specifically, we find that inside the paramagnetic phasemore » the Ising (J z) component of the Heisenberg exchange binds magnons into a two-particle bound state with zero total momentum and spin. This bound state condenses at D>D c, before single-particle excitations become unstable, and gives rise to a chiral liquid phase, which spontaneously breaks spatial inversion symmetry, but leaves the spin-rotational U(1) and time-reversal symmetries intact. This chiral liquid phase is characterized by a finite vector chirality without long-range dipolar magnetic order. In our analytical treatment, the chiral phase appears for arbitrarily small J z because the magnon-magnon attraction becomes singular near the single-magnon condensation transition. This phase exists in a finite range of D and transforms into the magnetically ordered state at some Dc. In conclusion, we corroborate our analytic treatment with numerical density matrix renormalization group calculations.« less

The Reverse Gyrase from Pyrobaculum calidifontis, a Novel Extremely Thermophilic DNA Topoisomerase Endowed with DNA Unwinding and Annealing Activities*

PubMed Central

Jamroze, Anmbreen; Perugino, Giuseppe; Valenti, Anna; Rashid, Naeem; Rossi, Mosè; Akhtar, Muhammad; Ciaramella, Maria

2014-01-01

Reverse gyrase is a DNA topoisomerase specific for hyperthermophilic bacteria and archaea. It catalyzes the peculiar ATP-dependent DNA-positive supercoiling reaction and might be involved in the physiological adaptation to high growth temperature. Reverse gyrase comprises an N-terminal ATPase and a C-terminal topoisomerase domain, which cooperate in enzyme activity, but details of its mechanism of action are still not clear. We present here a functional characterization of PcalRG, a novel reverse gyrase from the archaeon Pyrobaculum calidifontis. PcalRG is the most robust and processive reverse gyrase known to date; it is active over a wide range of conditions, including temperature, ionic strength, and ATP concentration. Moreover, it holds a strong ATP-inhibited DNA cleavage activity. Most important, PcalRG is able to induce ATP-dependent unwinding of synthetic Holliday junctions and ATP-stimulated annealing of unconstrained single-stranded oligonucleotides. Combined DNA unwinding and annealing activities are typical of certain helicases, but until now were shown for no other reverse gyrase. Our results suggest for the first time that a reverse gyrase shares not only structural but also functional features with evolutionary conserved helicase-topoisomerase complexes involved in genome stability. PMID:24347172

Reversible thermo-pneumatic valves on centrifugal microfluidic platforms.

PubMed

Aeinehvand, Mohammad Mahdi; Ibrahim, Fatimah; Harun, Sulaiman Wadi; Kazemzadeh, Amin; Rothan, Hussin A; Yusof, Rohana; Madou, Marc

2015-08-21

Centrifugal microfluidic systems utilize a conventional spindle motor to automate parallel biochemical assays on a single microfluidic disk. The integration of complex, sequential microfluidic procedures on these platforms relies on robust valving techniques that allow for the precise control and manipulation of fluid flow. The ability of valves to consistently return to their former conditions after each actuation plays a significant role in the real-time manipulation of fluidic operations. In this paper, we introduce an active valving technique that operates based on the deflection of a latex film with the potential for real-time flow manipulation in a wide range of operational spinning speeds. The reversible thermo-pneumatic valve (RTPV) seals or reopens an inlet when a trapped air volume is heated or cooled, respectively. The RTPV is a gas-impermeable valve composed of an air chamber enclosed by a latex membrane and a specially designed liquid transition chamber that enables the efficient usage of the applied thermal energy. Inputting thermo-pneumatic (TP) energy into the air chamber deflects the membrane into the liquid transition chamber against an inlet, sealing it and thus preventing fluid flow. From this point, a centrifugal pressure higher than the induced TP pressure in the air chamber reopens the fluid pathway. The behaviour of this newly introduced reversible valving system on a microfluidic disk is studied experimentally and theoretically over a range of rotational frequencies from 700 RPM to 2500 RPM. Furthermore, adding a physical component (e.g., a hemispherical rubber element) to induce initial flow resistance shifts the operational range of rotational frequencies of the RTPV to more than 6000 RPM. An analytical solution for the cooling of a heated RTPV on a spinning disk is also presented, which highlights the need for the future development of time-programmable RTPVs. Moreover, the reversibility and gas impermeability of the RTPV in the microfluidic networks are validated on a microfluidic disk designed for performing liquid circulation. Finally, an array of RTPVs is integrated into a microfluidic cartridge to enable sequential aliquoting for the conversion of dengue virus RNA to cDNA and the preparation of PCR reaction mixtures.

A MISO-ARX-Based Method for Single-Trial Evoked Potential Extraction.

PubMed

Yu, Nannan; Wu, Lingling; Zou, Dexuan; Chen, Ying; Lu, Hanbing

2017-01-01

In this paper, we propose a novel method for solving the single-trial evoked potential (EP) estimation problem. In this method, the single-trial EP is considered as a complex containing many components, which may originate from different functional brain sites; these components can be distinguished according to their respective latencies and amplitudes and are extracted simultaneously by multiple-input single-output autoregressive modeling with exogenous input (MISO-ARX). The extraction process is performed in three stages: first, we use a reference EP as a template and decompose it into a set of components, which serve as subtemplates for the remaining steps. Then, a dictionary is constructed with these subtemplates, and EPs are preliminarily extracted by sparse coding in order to roughly estimate the latency of each component. Finally, the single-trial measurement is parametrically modeled by MISO-ARX while characterizing spontaneous electroencephalographic activity as an autoregression model driven by white noise and with each component of the EP modeled by autoregressive-moving-average filtering of the subtemplates. Once optimized, all components of the EP can be extracted. Compared with ARX, our method has greater tracking capabilities of specific components of the EP complex as each component is modeled individually in MISO-ARX. We provide exhaustive experimental results to show the effectiveness and feasibility of our method.

Arm-in-Arm Response Regulator Dimers Promote Intermolecular Signal Transduction

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

Baker, Anna W.; Satyshur, Kenneth A.; Moreno Morales, Neydis

2016-02-01

ABSTRACT Bacteriophytochrome photoreceptors (BphPs) and their cognate response regulators make up two-component signal transduction systems which direct bacteria to mount phenotypic responses to changes in environmental light quality. Most of these systems utilize single-domain response regulators to transduce signals through unknown pathways and mechanisms. Here we describe the photocycle and autophosphorylation kinetics of RtBphP1, a red light-regulated histidine kinase from the desert bacteriumRamlibacter tataouinensis. RtBphP1 undergoes red to far-red photoconversion with rapid thermal reversion to the dark state. RtBphP1 is autophosphorylated in the dark; this activity is inhibited under red light. The RtBphP1 cognate response regulator, theR. tataouinensisbacteriophytochrome response regulatormore » (RtBRR), and a homolog, AtBRR fromAgrobacterium tumefaciens, crystallize unexpectedly as arm-in-arm dimers, reliant on a conserved hydrophobic motif, hFWAhL (where h is a hydrophobic M, V, L, or I residue). RtBRR and AtBRR dimerize distinctly from four structurally characterized phytochrome response regulators found in photosynthetic organisms and from all other receiver domain homodimers in the Protein Data Bank. A unique cacodylate-zinc-histidine tag metal organic framework yielded single-wavelength anomalous diffraction phases and may be of general interest. Examination of the effect of the BRR stoichiometry on signal transduction showed that phosphorylated RtBRR is accumulated more efficiently than the engineered monomeric RtBRR (RtBRR mon) in phosphotransfer reactions. Thus, we conclude that arm-in-arm dimers are a relevant signaling intermediate in this class of two-component regulatory systems. IMPORTANCEBphP histidine kinases and their cognate response regulators comprise widespread red light-sensing two-component systems. Much work on BphPs has focused on structural understanding of light sensing and on enhancing the natural infrared fluorescence of these proteins, rather than on signal transduction or the resultant phenotypes. To begin to address this knowledge gap, we solved the crystal structures of two single-domain response regulators encoded by a region immediately downstream of that encoding BphPs. We observed a previously unknown arm-in-arm dimer linkage. Monomerization via deletion of the C-terminal dimerization motif had an inhibitory effect on net response regulator phosphorylation, underlining the importance of these unusual dimers for signal transduction.« less

Time reversal focusing of elastic waves in plates for an educational demonstration.

PubMed

Heaton, Christopher; Anderson, Brian E; Young, Sarah M

2017-02-01

The purpose of this research is to develop a visual demonstration of time reversal focusing of vibrations in a thin plate. Various plate materials are tested to provide optimal conditions for time reversal focusing. Specifically, the reverberation time in each plate and the vibration coupling efficiency from a shaker to the plate are quantified to illustrate why a given plate provides the best spatially confined focus as well as the highest focal amplitude possible. A single vibration speaker and a scanning laser Doppler vibrometer (SLDV) are used to provide the time reversal focusing. Table salt is sprinkled onto the plate surface to allow visualization of the high amplitude, spatially localized time reversal focus; the salt is thrown upward only at the focal position. Spatial mapping of the vibration focusing on the plate using the SLDV is correlated to the visual salt jumping demonstration. The time reversal focusing is also used to knock over an object when the object is placed at the focal position; some discussion of optimal objects to use for this demonstration are given.

Giant reversible anisotropy changes at room temperature in a (La,Sr)MnO3/Pb(Mg,Nb,Ti)O3 magneto-electric heterostructure.

PubMed

Chopdekar, Rajesh Vilas; Buzzi, Michele; Jenkins, Catherine; Arenholz, Elke; Nolting, Frithjof; Takamura, Yayoi

2016-06-08

In a model artificial multiferroic system consisting of a (011)-oriented ferroelectric Pb(Mg,Nb,Ti)O3 substrate intimately coupled to an epitaxial ferromagnetic (La,Sr)MnO3 film, electric field pulse sequences of less than 6 kV/cm induce large, reversible, and bistable remanent strains. The magnetic anisotropy symmetry reversibly switches from a highly anisotropic two-fold state to a more isotropic one, with concomitant changes in resistivity. Anisotropy changes at the scale of a single ferromagnetic domain were measured using X-ray microscopy, with electric-field dependent magnetic domain reversal showing that the energy barrier for magnetization reversal is drastically lowered. Free energy calculations confirm this barrier lowering by up to 70% due to the anisotropic strain changes generated by the substrate. Thus, we demonstrate that an electric field pulse can be used to 'set' and 'reset' the magnetic anisotropy orientation and resistive state in the film, as well as to lower the magnetization reversal barrier, showing a promising route towards electric-field manipulation of multifunctional nanostructures at room temperature.

The behavioural consequences of sex reversal in dragons

PubMed Central

Li, Hong; Holleley, Clare E.; Elphick, Melanie; Georges, Arthur

2016-01-01

Sex differences in morphology, physiology, and behaviour are caused by sex-linked genes, as well as by circulating sex-steroid levels. Thus, a shift from genotypic to environmental sex determination may create an organism that exhibits a mixture of male-like and female-like traits. We studied a lizard species (Central Bearded Dragon, Pogona vitticeps), in which the high-temperature incubation of eggs transforms genetically male individuals into functional females. Although they are reproductively female, sex-reversed dragons (individuals with ZZ genotype reversed to female phenotype) resemble genetic males rather than females in morphology (relative tail length), general behaviour (boldness and activity level), and thermoregulatory tactics. Indeed, sex-reversed ‘females’ are more male-like in some behavioural traits than are genetic males. This novel phenotype may impose strong selection on the frequency of sex reversal within natural populations, facilitating rapid shifts in sex-determining systems. A single period of high incubation temperatures (generating thermally induced sex reversal) can produce functionally female individuals with male-like (or novel) traits that enhance individual fitness, allowing the new temperature-dependent sex-determining system to rapidly replace the previous genetically based one.

Base modifications affecting RNA polymerase and reverse transcriptase fidelity.

PubMed

Potapov, Vladimir; Fu, Xiaoqing; Dai, Nan; Corrêa, Ivan R; Tanner, Nathan A; Ong, Jennifer L

2018-06-20

Ribonucleic acid (RNA) is capable of hosting a variety of chemically diverse modifications, in both naturally-occurring post-transcriptional modifications and artificial chemical modifications used to expand the functionality of RNA. However, few studies have addressed how base modifications affect RNA polymerase and reverse transcriptase activity and fidelity. Here, we describe the fidelity of RNA synthesis and reverse transcription of modified ribonucleotides using an assay based on Pacific Biosciences Single Molecule Real-Time sequencing. Several modified bases, including methylated (m6A, m5C and m5U), hydroxymethylated (hm5U) and isomeric bases (pseudouridine), were examined. By comparing each modified base to the equivalent unmodified RNA base, we can determine how the modification affected cumulative RNA polymerase and reverse transcriptase fidelity. 5-hydroxymethyluridine and N6-methyladenosine both increased the combined error rate of T7 RNA polymerase and reverse transcriptases, while pseudouridine specifically increased the error rate of RNA synthesis by T7 RNA polymerase. In addition, we examined the frequency, mutational spectrum and sequence context of reverse transcription errors on DNA templates from an analysis of second strand DNA synthesis.

Phenotype of hepatocyte spheroids in Arg-GLY-Asp (RGD) containing a thermo-reversible extracellular matrix.

PubMed

Park, Keun-Hong; Bae, You Han

2002-07-01

The spheroid of specific cells is often regarded as the better form in artificial organs and mammalian cell bioreactors for improved cell-specific functions. In this study, freshly harvested primary rat hepatocytes, which had been cultivated as spheroids and entrapped in a synthetic thermo-reversible extracellular matrix, were examined for differentiated morphology and enhanced liver-specific functions as compared to a control set (hepatocytes in single-cell form). A copolymer of N-isopropylacrylamide (98 mole % in the feed) and acrylic acid (poly(NiPAAm-co-AAc)), and the adhesion molecule, an Arg-Gly-Asp (RGD)-incorporated thermo-reversible matrix, were used to entrap hepatocytes in the form of either spheroids or single cells. In a 28-day culture period, the spheroids in the RGD-incorporated gel maintained higher viability and produced albumin and urea at constant rates, while there was lower cell viability and less albumin secretion by the spheroids in p(NiPAAm-co-AAc). Hepatocytes cultured as spheroids in the RGD-incorporated gel would constitute a potentially useful three-dimensional cell system for application in a bio-artificial liver device.

Electrical characteristics in reverse electrodialysis using nanoporous membranes

NASA Astrophysics Data System (ADS)

Chanda, Sourayon; Tsai, Peichun Amy

2017-11-01

We experimentally and numerically investigate the effects of concentration difference and flow velocity on sustainable electricity generation and associated fluid dynamics using a single reverse electrodialysis (RED) cell. By exploiting the charge-selective nature of nanoporous interfaces, electrical energy is generated by reverse electrodialysis harnessing chemical Gibbs energy via a salinity gradient. Experimentally, a RED cell was designed with two reservoirs, which are separated by a nanoporous, cation-selective membrane. We injected deionized water through one reservoir, whereas a solution of high salt concentration through the other. The gradient of salt concentration primarily drives the flow in the charged nano-pores, due to the interplay between charge selectivity, diffusion processes, and electro-migration. The current-voltage characteristics of the single RED cell shows a linear current-voltage relationship, similar to an electrochemical cell. The membrane resistance is increased with increasing salt concentration difference and external flow rate. The present experimental work was further analyzed numerically to better understand the detailed electrical and flow fields under different concentration gradients and external flows. NSERC Discovery, Accelerator, and CRC Programs.

Vapomechanically Responsive Motion of Microchannel-Programmed Actuators.

PubMed

Zhang, Lidong; Naumov, Pancˇe; Du, Xuemin; Hu, Zhigao; Wang, Juan

2017-10-01

Materials that respond rapidly and reversibly to external stimuli currently stand among the top choices as actuators for real-world applications. Here, a series of programmable actuators fabricated as single- or bilayer elements is described that can reversibly respond to minute concentrations of acetone vapors. By using templates, microchannel structures are replicated onto the surface of two highly elastic polymers, polyvinylidene fluoride (PVDF) and polyvinyl alcohol, to induce chiral coiling upon exposure to acetone vapors. The vapomechanical coiling is reversible and can be conducted repeatedly over 100 times without apparent fatigue. If they are immersed in liquid acetone, the actuators are saturated with the solvent and temporarily lose their motility but regain their shape and activity within seconds after the solvent evaporates. The desorption of acetone from the PVDF layer is four times faster than its adsorption, and the actuator composed of a single PVDF layer maintains its ability to move over an acetone-soaked filter paper even after several days. The controllable and reproducible sensing capability of this smart material can be utilized for actuating dynamic elements in soft robotics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deterministic time-reversible thermostats: chaos, ergodicity, and the zeroth law of thermodynamics

NASA Astrophysics Data System (ADS)

Patra, Puneet Kumar; Sprott, Julien Clinton; Hoover, William Graham; Griswold Hoover, Carol

2015-09-01

The relative stability and ergodicity of deterministic time-reversible thermostats, both singly and in coupled pairs, are assessed through their Lyapunov spectra. Five types of thermostat are coupled to one another through a single Hooke's-law harmonic spring. The resulting dynamics shows that three specific thermostat types, Hoover-Holian, Ju-Bulgac, and Martyna-Klein-Tuckerman, have very similar Lyapunov spectra in their equilibrium four-dimensional phase spaces and when coupled in equilibrium or nonequilibrium pairs. All three of these oscillator-based thermostats are shown to be ergodic, with smooth analytic Gaussian distributions in their extended phase spaces (coordinate, momentum, and two control variables). Evidently these three ergodic and time-reversible thermostat types are particularly useful as statistical-mechanical thermometers and thermostats. Each of them generates Gibbs' universal canonical distribution internally as well as for systems to which they are coupled. Thus they obey the zeroth law of thermodynamics, as a good heat bath should. They also provide dissipative heat flow with relatively small nonlinearity when two or more such temperature baths interact and provide useful deterministic replacements for the stochastic Langevin equation.

Genetic Perturbation of the Maize Methylome[W

PubMed Central

Li, Qing; Hermanson, Peter J.; Zaunbrecher, Virginia M.; Song, Jawon; Wendt, Jennifer; Rosenbaum, Heidi; Madzima, Thelma F.; Sloan, Amy E.; Huang, Ji; Burgess, Daniel L.; Richmond, Todd A.; McGinnis, Karen M.; Meeley, Robert B.; Danilevskaya, Olga N.; Vaughn, Matthew W.; Kaeppler, Shawn M.; Jeddeloh, Jeffrey A.

2014-01-01

DNA methylation can play important roles in the regulation of transposable elements and genes. A collection of mutant alleles for 11 maize (Zea mays) genes predicted to play roles in controlling DNA methylation were isolated through forward- or reverse-genetic approaches. Low-coverage whole-genome bisulfite sequencing and high-coverage sequence-capture bisulfite sequencing were applied to mutant lines to determine context- and locus-specific effects of these mutations on DNA methylation profiles. Plants containing mutant alleles for components of the RNA-directed DNA methylation pathway exhibit loss of CHH methylation at many loci as well as CG and CHG methylation at a small number of loci. Plants containing loss-of-function alleles for chromomethylase (CMT) genes exhibit strong genome-wide reductions in CHG methylation and some locus-specific loss of CHH methylation. In an attempt to identify stocks with stronger reductions in DNA methylation levels than provided by single gene mutations, we performed crosses to create double mutants for the maize CMT3 orthologs, Zmet2 and Zmet5, and for the maize DDM1 orthologs, Chr101 and Chr106. While loss-of-function alleles are viable as single gene mutants, the double mutants were not recovered, suggesting that severe perturbations of the maize methylome may have stronger deleterious phenotypic effects than in Arabidopsis thaliana. PMID:25527708

An optical apparatus for rotation and trapping

PubMed Central

Gutiérrez-Medina, Braulio; Andreasson, Johan O. L.; Greenleaf, William J.; LaPorta, Arthur; Block, Steven M.

2010-01-01

We present details of the design, construction and testing of a single-beam optical tweezers apparatus capable of measuring and exerting torque, as well as force, on microfabricated, optically anisotropic particles (an ‘optical torque wrench’). The control of angular orientation is achieved by rotating the linear polarization of a trapping laser with an electro-optic modulator (EOM), which affords improved performance over previous designs. The torque imparted to the trapped particle is assessed by measuring the difference between left- and right-circular components of the transmitted light, and constant torque is maintained by feeding this difference signal back into a custom-designed electronic servo loop. The limited angular range of the EOM (±180°) is extended by rapidly reversing the polarization once a threshold angle is reached, enabling the torque clamp to function over unlimited, continuous rotations at high bandwidth. In addition, we developed particles suitable for rotation in this apparatus using microfabrication techniques. Altogether, the system allows for the simultaneous application of forces (~0.1–100 pN) and torques (~1–10,000 pN nm) in the study of biomolecules. As a proof of principle, we demonstrate how our instrument can be used to study the supercoiling of single DNA molecules. PMID:20627165

Efficient Single Tobamoviral Vector-Based Bioproduction of Broadly Neutralizing Anti-HIV-1 Monoclonal Antibody VRC01 in Nicotiana benthamiana Plants and Utility of VRC01 in Combination Microbicides

PubMed Central

Hamorsky, Krystal Teasley; Grooms-Williams, Tiffany W.; Husk, Adam S.; Bennett, Lauren J.; Palmer, Kenneth E.

2013-01-01

Broadly neutralizing monoclonal antibodies (bnMAbs) may offer powerful tools for HIV-1 preexposure prophylaxis, such as topical microbicides. However, this option is hampered due to expensive MAb biomanufacturing based on mammalian cell culture. To address this issue, we developed a new production system for bnMAb VRC01 in Nicotiana benthamiana plants using a tobamovirus replicon vector. Unlike conventional two-vector-based expression, this system was designed to overexpress full-length IgG1 from a single polypeptide by means of kex2p-like enzyme recognition sites introduced between the heavy and light chains. An enzyme-linked immunosorbent assay (ELISA) revealed that gp120-binding VRC01 IgG1 was maximally accumulated on 5 to 7 days following vector inoculation, yielding ∼150 mg of the bnMAb per kg of fresh leaf material. The plant-made VRC01 (VRC01p) was efficiently purified by protein A affinity followed by hydrophobic-interaction chromatography. ELISA, surface plasmon resonance, and an HIV-1 neutralization assay demonstrated that VRC01p has gp120-binding affinity and HIV-1-neutralization capacity virtually identical to the human-cell-produced counterpart. To advance VRC01p's use in topical microbicides, we analyzed combinations of the bnMAb with other microbicide candidates holding distinct antiviral mechanisms in an HIV-1 neutralization assay. VRC01p exhibited clear synergy with the antiviral lectin griffithsin, the CCR5 antagonist maraviroc, and the reverse transcriptase inhibitor tenofovir in multiple CCR5-tropic HIV-1 strains from clades A, B, and C. In summary, VRC01p is amenable to robust, rapid, and large-scale production and may be developed as an active component in combination microbicides with other anti-HIV agents such as antiviral lectins, CCR5 antagonists, and reverse transcriptase inhibitors. PMID:23403432

Method for distinguishing multiple targets using time-reversal acoustics

DOEpatents

Berryman, James G.

2004-06-29

A method for distinguishing multiple targets using time-reversal acoustics. Time-reversal acoustics uses an iterative process to determine the optimum signal for locating a strongly reflecting target in a cluttered environment. An acoustic array sends a signal into a medium, and then receives the returned/reflected signal. This returned/reflected signal is then time-reversed and sent back into the medium again, and again, until the signal being sent and received is no longer changing. At that point, the array has isolated the largest eigenvalue/eigenvector combination and has effectively determined the location of a single target in the medium (the one that is most strongly reflecting). After the largest eigenvalue/eigenvector combination has been determined, to determine the location of other targets, instead of sending back the same signals, the method sends back these time reversed signals, but half of them will also be reversed in sign. There are various possibilities for choosing which half to do sign reversal. The most obvious choice is to reverse every other one in a linear array, or as in a checkerboard pattern in 2D. Then, a new send/receive, send-time reversed/receive iteration can proceed. Often, the first iteration in this sequence will be close to the desired signal from a second target. In some cases, orthogonalization procedures must be implemented to assure the returned signals are in fact orthogonal to the first eigenvector found.

Study of Ni-Mo electrodeposition in direct and pulse-reverse current

NASA Astrophysics Data System (ADS)

Stryuchkova, Yu M.; Rybin, N. B.; Suvorov, D. V.; Gololobov, G. P.; Tolstoguzov, A. B.; Tarabrin, D. Yu; Serpova, M. A.; Korotchenko, V. A.; Slivkin, E. V.

2017-05-01

Process of electrochemical deposition of the coating based on a binary nickel-molybdenum alloy onto a nickel substrate under pulse mode with current reverse within the range of current density change from 2 to 9 A/dm2 has been researched. Coating structure and its surface morphology have been studied. Method of X-ray energy dispersive spectroscopy has determined a percentage ratio of alloy components in the coating. Mode to obtain the densest and smoothest deposits has been identified under considered terms.

Multi-component hydrogen storage material

DOEpatents

Faheem, Syed A.; Lewis, Gregory J.; Sachtler, J.W. Adriaan; Low, John J.; Lesch, David A.; Dosek, Paul M.; Wolverton, Christopher M.; Siegel, Donald J.; Sudik, Andrea C.; Yang, Jun

2010-09-07

A reversible hydrogen storage composition having an empirical formula of: Li.sub.(x+z)N.sub.xMg.sub.yB.sub.zH.sub.w where 0.4.ltoreq.x.ltoreq.0.8; 0.2.ltoreq.y.ltoreq.0.6; 0

A combined endovascular and open ''reverse hybrid'' technique for repair of complex juxtarenal inflammatory aortic aneurysms.

PubMed

Rigberg, David; Jimenez, Juan Carlos; Lawrence, Peter; Gelabert, Hugh

2009-01-01

Inflammatory abdominal aortic aneurysms (IAAA) can present significant challenges to surgeons, especially in the juxtarenal location where they may not be amenable to endovascular repair. The dense, inflammatory component of these lesions can encase adjacent structures including the duodenum, ureters, and inferior vena cava putting them at risk for injury during open exposure. We report a novel ''reverse hybrid'' technique using a combined endovascular and open approach for repair of large, juxtarenal IAAA's.

Simultaneous chiral discrimination of multiple profens by cyclodextrin-modified capillary electrophoresis in normal and reversed polarity modes.

PubMed

La, Sookie; Kim, Jiyung; Kim, Jung-Han; Goto, Junichi; Kim, Kyoung-Rae

2003-08-01

Simultaneous enantioseparations of nine profens for their accurate chiral discrimination were achieved by capillary electrophoresis (CE) in the normal polarity (NP) mode with a single cyclodextrin (CD) system and in the reversed polarity (RP) mode with a dual CD system. The single CD system in the NP mode employed heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TMbetaCD) added at 75 mM-100 mM 2-(N-morpholino)ethanesulfonic acid buffer (pH 6.0) as the optimum run buffer. The dual CD system operated in the RP mode used 30 mM TMbetaCD and 1.0% anionic carboxymethyl-beta-cyclodextrin dissolved in pH 3.0, 100 mM phosphoric acid-triethanolamine buffer containing 0.01% hexadimethrine bromide added to reverse the electroosmotic flow. Fairly good enantiomeric resolutions and the opposite enantiomer migration orders were achieved in the two modes. Relative migration times to internal standard under respective optimum conditions were characteristic of each enantiomer with good precision (< 2% relative standard deviation, RSD), thereby enabling to crosscheck the chemical identification of profens and also their accurate chiralities. The method linearity in the two modes was found to be adequate (r > or = 0.9991) for the chiral assay of the profens investigated. Simultaneous enantiomeric purity test of ibuprofen, ketoprofen and flurbiprofen in a mixture was feasible in a single analysis by the present method.

On the age of the hominid fossils at the Sima de los Huesos, Sierra de Atapuerca, Spain: paleomagnetic evidence.

PubMed

Parés, J M; Pérez-González, A; Weil, A B; Arsuaga, J L

2000-04-01

We report new paleomagnetic data for the Middle Pleistocene hominid-bearing strata in the Sima de los Huesos, North Spain. Sediments (brown muds with human and bear fossils and the underlying sterile clayey and sandy unit) preserve both normal and reversed magnetic components. The sterile unit has exclusively reversed magnetization, dating back to the Matuyama Chron, and thus is Lower Pleistocene in age. The overlying fossiliferous muds have a dominant normal magnetization that overprints a partially resolved reversed magnetization. These data are compatible with one of the reversal events that occurred during the Brunhes Chron. Combined with the existing U-series dates and evidence from the macro- and microfauna, these paleomagnetic results suggest an age of the hominid fossils between 325 to 205 ka, whereas the underlying sand and silts are older than 780 ka. Copyright 2000 Wiley-Liss, Inc.

Magnetization reversal mechanisms in hybrid resin-bonded Nd Fe B magnets

NASA Astrophysics Data System (ADS)

Plusa, D.; Dospial, M.; Slusarek, B.; Kotlarczyk, U.

2006-11-01

The magnetic properties of isotropic epoxy resin-bonded magnets prepared by mixing a hard magnetic powder made from melt quenched Nd-Fe-Co-B ribbons and a soft magnetic iron powder have been examined. The magnetization reversal processes and the magnetic parameters have been studied by the measurement of the virgin magnetization curves, the major and minor hysteresis loops and sets of recoil curves. From these recoil curves the field dependence of the reversible and irreversible magnetization components during the magnetization and demagnetization processes has been derived. The remanence relationship was used to study the nature of magnetic interaction between the grains. A study of interaction domains was conducted using optical microscopy. Groups of domains, each over several grains, were observed. It was found that the reversal process in the samples investigated involves the rotation of magnetization vectors in the iron powder grains and pinning of domain walls at the MQP-B grain boundaries.

Evaluation of using ferrofluid as an interface material for a field-reversible thermal connector

NASA Astrophysics Data System (ADS)

Yousif, Ahmed S.

The electrical functionality of an avionics chassis is limited due to heat dissipation limits. The limits arise due to the fact that components in an avionic computer boxes are packed very compactly, with the components mounted onto plug-in cards, and the harsh environment experienced by the chassis limits how heat can be dissipated from the cards. Convective and radiative heat transfer to the ambient are generally not possible. Therefore it is necessary to have heat transferred from the components conducted to the edge of the plug-in cards. The heat then needs to conduct from the card edge to a cold block that not only holds the card in place, but also removes the generated heat by some heat transfer fluid that is circulated through the cold block. The interface between the plug-in card and the cold block typically has a high thermal resistance since it is necessary for the card to have the capability to be re-workable, meaning that the card can be removed and then returned to the chassis. Reducing the thermal resistance of the interface is the objective of the current study and the topic of this thesis. The current design uses a pressure interface between the card and cold block. The contact pressure is increased through the addition of a wedgelock, which is a field-reversible mechanical connector. To use a wedgelock, the cold block has channels milled on the surface with widths that are larger than the thickness of the plug-in card and the un-expanded wedgelock. The card edge is placed in the channel and placed against one of the channel walls. A wedgelock is then placed between the card and the other channel wall. The wedgelock is then expanded by using either a screw or a lever. As the wedgelock expands it fills in the remaining channel gap and bears against the other face of the plug-in card. The majority of heat generated by the components on the plug-in card is forced to conduct from the card into the wall of the cold block, effectively a single sided, dry conduction heat transfer path. Having started as a student design competition named RevCon Challenge, work was performed to evaluate the use of new field-reversible thermal connectors. The new design proposed by the University of Missouri utilized oil based iron nanoparticles, commonly known as a ferrofluid, as a thermal interface material. By using a liquid type of interface material the channel gap can be reduced to a few micrometers, within machining tolerances, and heat can be dissipated off both sides of the card. The addition of nanoparticles improves the effective thermal conductivity of base fluid. The use of iron nanoparticles allows magnets to be used to hold the fluid in place, so the electronic cards may be easily inserted and removed while keeping the ferrofluid in the cold block channel. The ferrofluid-based design which was investigated has shown lower thermal resistance than the current wedgelock design. These results open the door for further development of electronic cards by using higher heat emitting components without compromising the simplicity of attaching/detaching cards from cooling plates.

Self-digitization microfluidic chip for absolute quantification of mRNA in single cells.

PubMed

Thompson, Alison M; Gansen, Alexander; Paguirigan, Amy L; Kreutz, Jason E; Radich, Jerald P; Chiu, Daniel T

2014-12-16

Quantification of mRNA in single cells provides direct insight into how intercellular heterogeneity plays a role in disease progression and outcomes. Quantitative polymerase chain reaction (qPCR), the current gold standard for evaluating gene expression, is insufficient for providing absolute measurement of single-cell mRNA transcript abundance. Challenges include difficulties in handling small sample volumes and the high variability in measurements. Microfluidic digital PCR provides far better sensitivity for minute quantities of genetic material, but the typical format of this assay does not allow for counting of the absolute number of mRNA transcripts samples taken from single cells. Furthermore, a large fraction of the sample is often lost during sample handling in microfluidic digital PCR. Here, we report the absolute quantification of single-cell mRNA transcripts by digital, one-step reverse transcription PCR in a simple microfluidic array device called the self-digitization (SD) chip. By performing the reverse transcription step in digitized volumes, we find that the assay exhibits a linear signal across a wide range of total RNA concentrations and agrees well with standard curve qPCR. The SD chip is found to digitize a high percentage (86.7%) of the sample for single-cell experiments. Moreover, quantification of transferrin receptor mRNA in single cells agrees well with single-molecule fluorescence in situ hybridization experiments. The SD platform for absolute quantification of single-cell mRNA can be optimized for other genes and may be useful as an independent control method for the validation of mRNA quantification techniques.

Evidence for single metal two electron oxidative addition and reductive elimination at uranium.

PubMed

Gardner, Benedict M; Kefalidis, Christos E; Lu, Erli; Patel, Dipti; McInnes, Eric J L; Tuna, Floriana; Wooles, Ashley J; Maron, Laurent; Liddle, Stephen T

2017-12-01

Reversible single-metal two-electron oxidative addition and reductive elimination are common fundamental reactions for transition metals that underpin major catalytic transformations. However, these reactions have never been observed together in the f-block because these metals exhibit irreversible one- or multi-electron oxidation or reduction reactions. Here we report that azobenzene oxidises sterically and electronically unsaturated uranium(III) complexes to afford a uranium(V)-imido complex in a reaction that satisfies all criteria of a single-metal two-electron oxidative addition. Thermolysis of this complex promotes extrusion of azobenzene, where H-/D-isotopic labelling finds no isotopomer cross-over and the non-reactivity of a nitrene-trap suggests that nitrenes are not generated and thus a reductive elimination has occurred. Though not optimally balanced in this case, this work presents evidence that classical d-block redox chemistry can be performed reversibly by f-block metals, and that uranium can thus mimic elementary transition metal reactivity, which may lead to the discovery of new f-block catalysis.

Optocontrol of glutamate receptor activity by single side-chain photoisomerization

PubMed Central

Klippenstein, Viktoria; Hoppmann, Christian; Ye, Shixin; Wang, Lei; Paoletti, Pierre

2017-01-01

Engineering light-sensitivity into proteins has wide ranging applications in molecular studies and neuroscience. Commonly used tethered photoswitchable ligands, however, require solvent-accessible protein labeling, face structural constrains, and are bulky. Here, we designed a set of optocontrollable NMDA receptors by directly incorporating single photoswitchable amino acids (PSAAs) providing genetic encodability, reversibility, and site tolerance. We identified several positions within the multi-domain receptor endowing robust photomodulation. PSAA photoisomerization at the GluN1 clamshell hinge is sufficient to control glycine sensitivity and activation efficacy. Strikingly, in the pore domain, flipping of a M3 residue within a conserved transmembrane cavity impacts both gating and permeation properties. Our study demonstrates the first detection of molecular rearrangements in real-time due to the reversible light-switching of single amino acid side-chains, adding a dynamic dimension to protein site-directed mutagenesis. This novel approach to interrogate neuronal protein function has general applicability in the fast expanding field of optopharmacology. DOI: http://dx.doi.org/10.7554/eLife.25808.001 PMID:28534738

Development of a Kevlar/PMR-15 reduced drag DC-9 nacelle fairing

NASA Technical Reports Server (NTRS)

Kawai, R. T.; Hrach, F. J.

1980-01-01

The paper describes an advanced composite fairing designed to reduce drag on DC-9 nacelles as a part of the NASA Engine Component Improvement Program. This fairing is the aft enclosure for the thrust reverser actuator system on JT8D engine nacelles and is subjected to a 500 F exhaust flow during the reverse thrust. A reduced-drag configuration was developed by using in-flight tuft surveys for flow visualization in order to identify areas with low-quality flow, and then modifying the aerodynamic lines to improve the flow. A fabrication method for molding the part in an autoclave was developed; this material system is suitable for 500 F. The resultant composite fairing reduces the overall aircraft drag 1% with a weight reduction of 40% when compared with a metal component.

Synthesis of Stable Microcapsules from Trematode Eggshell Components

DTIC Science & Technology

1990-06-30

NO Arlington, VA 22217-5000 61153N RR4106 11 TITLE (Include Security Classification) (u) Synthesis of Stable Microcapsules from Trematode Eggshell...Continue on reverse if necessary and identify by block number) The trematode Fasciola hepatica produces a unique protein eggshell or microcapsule the...proteins to produce a hard quinone tanned microcapsule with unusual properties. The focus of this project is to i) characterize the protein components

Reversal learning as a measure of impulsive and compulsive behavior in addictions.

PubMed

Izquierdo, Alicia; Jentsch, J David

2012-01-01

Our ability to measure the cognitive components of complex decision-making across species has greatly facilitated our understanding of its neurobiological mechanisms. One task in particular, reversal learning, has proven valuable in assessing the inhibitory processes that are central to executive control. Reversal learning measures the ability to actively suppress reward-related responding and to disengage from ongoing behavior, phenomena that are biologically and descriptively related to impulsivity and compulsivity. Consequently, reversal learning could index vulnerability for disorders characterized by impulsivity such as proclivity for initial substance abuse as well as the compulsive aspects of dependence. Though we describe common variants and similar tasks, we pay particular attention to discrimination reversal learning, its supporting neural circuitry, neuropharmacology and genetic determinants. We also review the utility of this task in measuring impulsivity and compulsivity in addictions. We restrict our review to instrumental, reward-related reversal learning studies as they are most germane to addiction. The research reviewed here suggests that discrimination reversal learning may be used as a diagnostic tool for investigating the neural mechanisms that mediate impulsive and compulsive aspects of pathological reward-seeking and -taking behaviors. Two interrelated mechanisms are posited for the neuroadaptations in addiction that often translate to poor reversal learning: frontocorticostriatal circuitry dysregulation and poor dopamine (D2 receptor) modulation of this circuitry. These data suggest new approaches to targeting inhibitory control mechanisms in addictions.

Time reversal invariance for a nonlinear scatterer exhibiting contact acoustic nonlinearity

NASA Astrophysics Data System (ADS)

Blanloeuil, Philippe; Rose, L. R. Francis; Veidt, Martin; Wang, Chun H.

2018-03-01

The time reversal invariance of an ultrasonic plane wave interacting with a contact interface characterized by a unilateral contact law is investigated analytically and numerically. It is shown analytically that despite the contact nonlinearity, the re-emission of a time reversed version of the reflected and transmitted waves can perfectly recover the original pulse shape, thereby demonstrating time reversal invariance for this type of contact acoustic nonlinearity. With the aid of finite element modelling, the time-reversal analysis is extended to finite-size nonlinear scatterers such as closed cracks. The results show that time reversal invariance holds provided that all the additional frequencies generated during the forward propagation, such as higher harmonics, sub-harmonics and zero-frequency component, are fully included in the retro-propagation. If the scattered waves are frequency filtered during receiving or transmitting, such as through the use of narrowband transducers, the recombination of the time-reversed waves will not exactly recover the original incident wave. This discrepancy due to incomplete time invariance can be exploited as a new method for characterizing damage by defining damage indices that quantify the departure from time reversal invariance. The sensitivity of these damage indices for various crack lengths and contact stress levels is investigated computationally, indicating some advantages of this narrowband approach relative to the more conventional measurement of higher harmonic amplitude, which requires broadband transducers.

The allosteric HIV-1 integrase inhibitor BI-D affects virion maturation but does not influence packaging of a functional RNA genome.

PubMed

van Bel, Nikki; van der Velden, Yme; Bonnard, Damien; Le Rouzic, Erwann; Das, Atze T; Benarous, Richard; Berkhout, Ben

2014-01-01

The viral integrase (IN) is an essential protein for HIV-1 replication. IN inserts the viral dsDNA into the host chromosome, thereby aided by the cellular co-factor LEDGF/p75. Recently a new class of integrase inhibitors was described: allosteric IN inhibitors (ALLINIs). Although designed to interfere with the IN-LEDGF/p75 interaction to block HIV DNA integration during the early phase of HIV-1 replication, the major impact was surprisingly found on the process of virus maturation during the late phase, causing a reverse transcription defect upon infection of target cells. Virus particles produced in the presence of an ALLINI are misformed with the ribonucleoprotein located outside the virus core. Virus assembly and maturation are highly orchestrated and regulated processes in which several viral proteins and RNA molecules closely interact. It is therefore of interest to study whether ALLINIs have unpredicted pleiotropic effects on these RNA-related processes. We confirm that the ALLINI BI-D inhibits virus replication and that the produced virus is non-infectious. Furthermore, we show that the wild-type level of HIV-1 genomic RNA is packaged in virions and these genomes are in a dimeric state. The tRNAlys3 primer for reverse transcription was properly placed on this genomic RNA and could be extended ex vivo. In addition, the packaged reverse transcriptase enzyme was fully active when extracted from virions. As the RNA and enzyme components for reverse transcription are properly present in virions produced in the presence of BI-D, the inhibition of reverse transcription is likely to reflect the mislocalization of the components in the aberrant virus particle.

Chemical and magnetic properties of rapidly cooled metastable ferri-ilmenite solid solutions - IV: the fine structure of self-reversed thermoremanent magnetization

NASA Astrophysics Data System (ADS)

Robinson, Peter; McEnroe, S. A.; Fabian, K.; Harrison, R. J.; Thomas, C. I.; Mukai, H.

2014-03-01

Magnetic experiments, a Monte Carlo simulation and transmission electron microscopy observations combine to confirm variable chemical phase separation during quench and annealing of metastable ferri-ilmenite compositions, caused by inhomogeneous Fe-Ti ordering and anti-ordering. Separation begins near interfaces between growing ordered and anti-ordered domains, the latter becoming progressively enriched in ilmenite component, moving the Ti-impoverished hematite component into Fe-enriched diffusion waves near the interfaces. Even when disordered regions are eliminated, Fe-enriched waves persist and enlarge on anti-phase boundaries between growing and shrinking ordered and anti-ordered domains. Magnetic results and conceptual models show that magnetic ordering with falling T initiates in the Fe-enriched wave crests. Although representing only a tiny fraction of material, identified at highest Ts on a field-cooling curve, they control the `pre-destiny' of progressive magnetization at lower T. They can provide a positive magnetic moment in a minority of ordered ferrimagnetic material, which, by exchange coupling, then creates a self-reversed negative moment in the remaining majority. Four Ts or T ranges are recognized on typical field-cooling curves: TPD is the T range of `pre-destination'; TC is the predominant Curie T where major positive magnetization increases sharply; TMAX is where magnetization reaches a positive maximum, beyond which it is outweighed by self-reversed magnetization and TZM is the T where total magnetization passes zero. Disposition of these Ts on cooling curves indicate the fine structure of self-reversed thermoremanent magnetization. These results confirm much earlier suspicions that the `x-phase' responsible for self-reversed magnetization resides in Fe-enriched phase boundaries.

Reversible and irreversible low-pressure membrane foulants in drinking water treatment: Identification by principal component analysis of fluorescence EEM and mitigation by biofiltration pretreatment.

PubMed

Peldszus, Sigrid; Hallé, Cynthia; Peiris, Ramila H; Hamouda, Mohamed; Jin, Xiaohui; Legge, Raymond L; Budman, Hector; Moresoli, Christine; Huck, Peter M

2011-10-15

With the increased use of membranes in drinking water treatment, fouling--particularly the hydraulically irreversible type--remains the main operating issue that hinders performance and increases operational costs. The main challenge in assessing fouling potential of feed water is to accurately detect and quantify feed water constituents responsible for membrane fouling. Utilizing fluorescence excitation-emission matrices (EEM), protein-like substances, humic and fulvic acids, and particulate/colloidal matter can be detected with high sensitivity in surface waters. The application of principal component analysis to fluorescence EEMs allowed estimation of the impact of surface water constituents on reversible and irreversible membrane fouling. This technique was applied to experimental data from a two year bench-scale study that included thirteen experiments investigating the fouling potential of Grand River water (Ontario, Canada) and the effect of biofiltration pre-treatment on the level of foulants during ultrafiltration (UF). Results showed that, although the content of protein-like substances in this membrane feed water (=biofiltered natural water) was much lower than commonly found in wastewater applications, the content of protein-like substances was still highly correlated with irreversible fouling of the UF membrane. In addition, there is evidence that protein-like substances and particulate/colloidal matter formed a combined fouling layer, which contributed to both reversible and irreversible fouling. It is suggested that fouling transitions from a reversible to an irreversible regime depending on feed composition and operating time. Direct biofiltration without prior coagulant addition reduced the protein-like content of the membrane feed water which in turn reduced the irreversible fouling potential for UF membranes. Biofilters also decreased reversible fouling, and for both types of fouling higher biofilter contact times were beneficial. Copyright © 2011 Elsevier Ltd. All rights reserved.

The topology of intrasector reversals of the interplanetary magnetic field

NASA Astrophysics Data System (ADS)

Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

1996-11-01

A technique has been developed recently to determine the polarities of interplanetary magnetic fields relative to their origins at the Sun by comparing energetic electron flow directions with local magnetic field directions. Here we use heat flux electrons from the Los Alamos National Laboratory (LANL) plasma detector on the ISEE 3 spacecraft to determine the field polarities. We examine periods within well-defined magnetic sectors when the field directions appear to be reversed from the normal spiral direction of the sector. About half of these intrasector field reversals (IFRs) are cases in which the polarities match those of the surrounding sectors, indicating that those fields have been folded back toward the Sun. The more interesting cases are those with polarity reversals. We find no clear cases of isolated reverse polarity fields, which suggests that islands of reverse polarity in the solar source dipole field probably do not exist. The IFRs with polarity reversals are strongly associated with periods of bidirectional electron flows, suggesting that those fields occur only in conjunction with closed fields. We propose that both those IFRs and the bidirectional flows are signatures of coronal mass ejections (CMEs). In that case, many interplanetary CMEs are larger and more complex than previously thought, consisting of both open and closed field components.

Dipping Magnetic Reversal Boundaries at Endeavor Deep: Implications for Crustal Accretion

NASA Astrophysics Data System (ADS)

Pockalny, R. A.; Shields, A. C.; Larson, R. L.; Popham, C.

2005-12-01

Endeavor Deep, created by ongoing rifting along the northeastern boundary of the Juan Fernandez Microplate, provides a generous 75-km long view of the upper 1-3 km of oceanic crust created ~3 Ma at a fast-spreading ridge (~80 km/Myr, half-rate). Recent near-bottom surveys with the ROV Jason collected high-resolution video, rock samples, and 3-component magnetometer data along a 5 km-wide section of the southern wall of the deep. The video and rock samples define a crustal section with 300-500 m of primarily pillows and flows overlying a 400-500 m transition zone of extrusives and dykes. Forward modeling of the total magnetic intensity calculated from the 3-component magnetometer data identifies a magnetic polarity reversal that corresponds to a reversal boundary within magnetic anomaly 2a (C2An.2r - C2AN.3n , ~3.33 Ma). The location of the modeled polarity transition suggests the reversal boundary dips downward toward the original ridge axis with shallow dips (15 degrees) in the extrusive layer becoming increasingly steeper (25 degrees) in the deeper transition zone. The dipping character of the reversal boundary has also been observed along the walls of the Blanco Fracture Zone and is consistent with evolving crustal accretion models for seafloor created at intermediate- and fast-spreading rates, which predicts the rotation of the upper extrusive layer back toward the ridge axis. As a consequence of this rotation, originally horizontal flow boundaries will dip back toward the ridge axis and the magnitude of the dip will increase with depth into the crustal section. A small reversed magnetic polarity is also observed deeper within normally magnetized C2AN.3n chron, but with a very shallow dip (3-5 degrees). We doubt this is another normal-reverse-normal polarity transition, since the anomaly suspiciously coincides with the transition from dykes to extrusives. Therefore, we believe this anomaly is either the result of an edge-effect created by the different magnetic properties of the dykes and extrusives or evidence off-axis volcanism that occurred during a more recent period of normal magnetization.

Monitoring Mitochondrial Pyruvate Carrier Activity in Real Time Using a BRET-Based Biosensor: Investigation of the Warburg Effect.

PubMed

Compan, Vincent; Pierredon, Sandra; Vanderperre, Benoît; Krznar, Petra; Marchiq, Ibtissam; Zamboni, Nicola; Pouyssegur, Jacques; Martinou, Jean-Claude

2015-08-06

The transport of pyruvate into mitochondria requires a specific carrier, the mitochondrial pyruvate carrier (MPC). The MPC represents a central node of carbon metabolism, and its activity is likely to play a key role in bioenergetics. Until now, investigation of the MPC activity has been limited. However, the recent molecular identification of the components of the carrier has allowed us to engineer a genetically encoded biosensor and to monitor the activity of the MPC in real time in a cell population or in a single cell. We report that the MPC activity is low in cancer cells, which mainly rely on glycolysis to generate ATP, a characteristic known as the Warburg effect. We show that this low activity can be reversed by increasing the concentration of cytosolic pyruvate, thus increasing oxidative phosphorylation. This biosensor represents a unique tool to investigate carbon metabolism and bioenergetics in various cell types. Copyright © 2015 Elsevier Inc. All rights reserved.

Simple and rapid high-performance liquid chromatographic method for the determination of aspartame and its metabolites in foods.

PubMed

Gibbs, B F; Alli, I; Mulligan, C N

1996-02-23

A method for the determination of aspartame (N-L-alpha-aspartyl-L-phenylalanine methyl ester) and its metabolites, applicable on a routine quality assurance basis, is described. Liquid samples (diet Coke, 7-Up, Pepsi, etc.) were injected directly onto a mini-cartridge reversed-phase column on a high-performance liquid chromatographic system, whereas solid samples (Equal, hot chocolate powder, pudding, etc.) were extracted with water. Optimising chromatographic conditions resulted in resolved components of interest within 12 min. The by-products were confirmed by mass spectrometry. Although the method was developed on a two-pump HPLC system fitted with a diode-array detector, it is straightforward and can be transformed to the simplest HPLC configuration. Using a single-piston pump (with damper), a fixed-wavelength detector and a recorder/integrator, the degradation of products can be monitored as they decompose. The results obtained were in harmony with previously reported tedious methods. The method is simple, rapid, quantitative and does not involve complex, hazardous or toxic chemistry.

Formation of the sacrum requires down-regulation of sonic hedgehog signaling in the sacral intervertebral discs.

PubMed

Bonavita, Raffaella; Vincent, Kathleen; Pinelli, Robert; Dahia, Chitra Lekha

2018-05-21

In humans, the sacrum forms an important component of the pelvic arch, and it transfers the weight of the body to the lower limbs. The sacrum is formed by collapse of the intervertebral discs (IVDs) between the five sacral vertebrae during childhood, and their fusion to form a single bone. We show that collapse of the sacral discs in the mouse is associated with the down-regulation of sonic hedgehog (SHH) signaling in the nucleus pulposus (NP) of the disc, and many aspects of this phenotype can be reversed by experimental postnatal activation of HH signaling. We have previously shown that SHH signaling is essential for the normal postnatal growth and differentiation of intervertebral discs elsewhere in the spine, and that loss of SHH signaling leads to pathological disc degeneration, a very common disorder of aging. Thus, loss of SHH is pathological in one region of the spine but part of normal development in another. © 2018. Published by The Company of Biologists Ltd.

The tangential velocity of M31: CLUES from constrained simulations

NASA Astrophysics Data System (ADS)

Carlesi, Edoardo; Hoffman, Yehuda; Sorce, Jenny G.; Gottlöber, Stefan; Yepes, Gustavo; Courtois, Hélène; Tully, R. Brent

2016-07-01

Determining the precise value of the tangential component of the velocity of M31 is a non-trivial astrophysical issue that relies on complicated modelling. This has recently lead to conflicting estimates, obtained by several groups that used different methodologies and assumptions. This Letter addresses the issue by computing a Bayesian posterior distribution function of this quantity, in order to measure the compatibility of those estimates with Λ cold dark matter (ΛCDM). This is achieved using an ensemble of Local Group (LG) look-alikes collected from a set of constrained simulations (CSs) of the local Universe, and a standard unconstrained ΛCDM. The latter allows us to build a control sample of LG-like pairs and to single out the influence of the environment in our results. We find that neither estimate is at odds with ΛCDM; however, whereas CSs favour higher values of vtan, the reverse is true for estimates based on LG samples gathered from unconstrained simulations, overlooking the environmental element.

[FROM STATISTICAL ASSOCIATIONS TO SCIENTIFIC CAUSALITY].

PubMed

Golan, Daniel; Linn, Shay

2015-06-01

The pathogenesis of most chronic diseases is complex and probably involves the interaction of multiple genetic and environmental risk factors. One way to learn about disease triggers is from statistically significant associations in epidemiological studies. However, associations do not necessarily prove causation. Associations can commonly result from bias, confounding and reverse causation. Several paradigms for causality inference have been developed. Henle-Koch postulates are mainly applied for infectious diseases. Austin Bradford Hill's criteria may serve as a practical tool to weigh the evidence regarding the probability that a single new risk factor for a given disease is indeed causal. These criteria are irrelevant for estimating the causal relationship between exposure to a risk factor and disease whenever biological causality has been previously established. Thus, it is highly probable that past exposure of an individual to definite carcinogens is related to his cancer, even without proving an association between this exposure and cancer in his group. For multifactorial diseases, Rothman's model of interacting sets of component causes can be applied.

Biflorin Ameliorates Memory Impairments Induced by Cholinergic Blockade in Mice

PubMed Central

Jeon, Se Jin; Kim, Boseong; Ryu, Byeol; Kim, Eunji; Lee, Sunhee; Jang, Dae Sik; Ryu, Jong Hoon

2017-01-01

To examine the effect of biflorin, a component of Syzygium aromaticum, on memory deficit, we introduced a scopolamine-induced cognitive deficit mouse model. A single administration of biflorin increased latency time in the passive avoidance task, ameliorated alternation behavior in the Y-maze, and increased exploration time in the Morris water maze task, indicating the improvement of cognitive behaviors against cholinergic dysfunction. The biflorin-induced reverse of latency in the scopolamine-treated group was attenuated by MK-801, an NMDA receptor antagonist. Biflorin also enhanced cognitive function in a naïve mouse model. To understand the mechanism of biflorin for memory amelioration, we performed Western blot. Biflorin increased the activation of protein kinase C-ζ and its downstream signaling molecules in the hippocampus. These results suggest that biflorin ameliorates drug-induced memory impairment by modulation of protein kinase C-ζ signaling in mice, implying that biflorin could function as a possible therapeutic agent for the treatment of cognitive problems. PMID:27829270

A Novel Prediction Method about Single Components of Analog Circuits Based on Complex Field Modeling

PubMed Central

Tian, Shulin; Yang, Chenglin

2014-01-01

Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator) calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits' single components. At last, it uses particle filter (PF) to update parameters for the model and predicts remaining useful performance (RUP) of analog circuits' single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments. PMID:25147853

Specific features of electroluminescence in heterostructures with InSb quantum dots in an InAs matrix

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

Parkhomenko, Ya. A.; Ivanov, E. V.; Moiseev, K. D., E-mail: mkd@iropt2.ioffe.rssi.ru

2013-11-15

The electrical and electroluminescence properties of a single narrow-gap heterostructure based on a p-n junction in indium arsenide, containing a single layer of InSb quantum dots in the InAs matrix, are studied. The presence of quantum dots has a significant effect on the shape of the reverse branch of the current-voltage characteristic of the heterostructure. Under reverse bias, the room-temperature electroluminescence spectra of the heterostructure with quantum dots, in addition to a negative-luminescence band with a maximum at the wavelength {lambda} = 3.5 {mu}m, contained a positive-luminescence emission band at 3.8 {mu}m, caused by radiative transitions involving localized states ofmore » quantum dots at the type-II InSb/InAs heterointerface.« less

Quantifying the Electrocatalytic Turnover of Vitamin B12-Mediated Dehalogenation on Single Soft Nanoparticles.

PubMed

Cheng, Wei; Compton, Richard G

2016-02-12

We report the electrocatalytic dehalogenation of trichloroethylene (TCE) by single soft nanoparticles in the form of Vitamin B12 -containing droplets. We quantify the turnover number of the catalytic reaction at the single soft nanoparticle level. The kinetic data shows that the binding of TCE with the electro-reduced vitamin in the Co(I) oxidation state is chemically reversible. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Higher outcomes of vasectomy reversal in men with the same female partner as before vasectomy.

PubMed

Ostrowski, Kevin A; Polackwich, A Scott; Kent, Joe; Conlin, Michael J; Hedges, Jason C; Fuchs, Eugene F

2015-01-01

We reviewed fertility outcomes of vasectomy reversal at a high surgical volume center in men with the same female partner as before vasectomy. We retrospectively studied a prospective database. All vasectomy reversals were performed by a single surgeon (EFF). Patients who underwent microsurgical vasectomy reversal and had the same female partner as before vasectomy were identified from 1978 to 2011. Pregnancy and live birth rates, procedure type (bilateral vasovasostomy, bilateral vasoepididymostomy, unilateral vasovasostomy or unilateral vasoepididymostomy), patency rate, time from reversal and spouse age were evaluated. We reviewed the records of 3,135 consecutive microsurgical vasectomy reversals. Of these patients 524 (17%) who underwent vasectomy reversal had the same female partner as before vasectomy. Complete information was available on 258 patients (49%), who had a 94% vas patency rate. The clinical pregnancy rate was 83% by natural means compared to 60% in our general vasectomy reversal population (p <0.0001). On logistic regression analysis controlling for female partner and patient ages, years from vasectomy and vasectomy reversal with the same female partner the OR was 2 (p <0.007). Average time from vasectomy was 5.7 years. Average patient and female partner age at reversal was 38.9 and 33.2 years, respectively. Outcomes of clinical pregnancy and live birth rates are higher in men who undergo microsurgical vasectomy reversal with the same female partner. These outcomes may be related to a shorter interval from vasectomy, previous fertility and couple motivation. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Effects of Low Level Radiation exposure on Neurogenesis and Cognitive Function: Mechanisms and Prevention

DTIC Science & Technology

2005-09-01

precursor cells in culture with uX-lipoic acid reverses the density dependent changes observed in culture; this compound may provide an effective means...inhibited growth of precursor cells in vitro; - Antioxidant treatment of neural precursor cells in culture with a-lipoic acid (ALA) reverses the...with a single lO-Gy dose, and tissues avidin-biotinylated pemxidase complex; GFAP, glial fibrillary acidic protein; DAB, 3,3’- were collected from 6 to

Effects of cooling rate on particle rearrangement statistics: Rapidly cooled glasses are more ductile and less reversible.

PubMed

Fan, Meng; Wang, Minglei; Zhang, Kai; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

2017-02-01

Amorphous solids, such as metallic, polymeric, and colloidal glasses, display complex spatiotemporal response to applied deformations. In contrast to crystalline solids, during loading, amorphous solids exhibit a smooth crossover from elastic response to plastic flow. In this study, we investigate the mechanical response of binary Lennard-Jones glasses to athermal, quasistatic pure shear as a function of the cooling rate used to prepare them. We find several key results concerning the connection between strain-induced particle rearrangements and mechanical response. We show that the energy loss per strain dU_{loss}/dγ caused by particle rearrangements for more rapidly cooled glasses is larger than that for slowly cooled glasses. We also find that the cumulative energy loss U_{loss} can be used to predict the ductility of glasses even in the putative linear regime of stress versus strain. U_{loss} increases (and the ratio of shear to bulk moduli decreases) with increasing cooling rate, indicating enhanced ductility. In addition, we characterized the degree of reversibility of particle motion during a single shear cycle. We find that irreversible particle motion occurs even in the linear regime of stress versus strain. However, slowly cooled glasses, which undergo smaller rearrangements, are more reversible during a single shear cycle than rapidly cooled glasses. Thus, we show that more ductile glasses are also less reversible.

Ionic Control of the Reversal Response of Cilia in Paramecium caudatum

PubMed Central

Naitoh, Yutaka

1968-01-01

The duration of ciliary reversal of Paramecium caudatum in response to changes in external ionic factors was determined with various ionic compositions of both equilibration and stimulation media. The reversal response was found to occur when calcium ions bound by an inferred cellular cation exchange system were liberated in exchange for externally applied cations other than calcium. Factors which affect the duration of the response were (a) initial amount of calcium bound by the cation exchange system, (b) final amount of calcium bound by the system after equilibration with the stimulation medium, and (c) concentration of calcium ions in the stimulation medium. An empirical equation is presented which relates the duration of the response to these three factors. On the basis of these and previously published data, the following hypothesis is proposed for the mechanism underlying ciliary reversal in response to cationic stimulation: Ca++ liberated from the cellular cation exchange system activates a contractile system which is energized by ATP. Contraction of this component results in the reversal of effective beat direction of cilia by a mechanism not yet understood. The duration of reversal in live paramecia is related to the time course of bound calcium release. PMID:4966766

Quantitative characterization of the atomic-scale structure of oxyhydroxides in rusts formed on steel surfaces

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

Saito, M.; Suzuki, S.; Kimura, M.

Quantitative X-ray structural analysis coupled with anomalous X-ray scattering has been used for characterizing the atomic-scale structure of rust formed on steel surfaces. Samples were prepared from rust layers formed on the surfaces of two commercial steels. X-ray scattered intensity profiles of the two samples showed that the rusts consisted mainly of two types of ferric oxyhydroxide, {alpha}-FeOOH and {gamma}-FeOOH. The amounts of these rust components and the realistic atomic arrangements in the components were estimated by fitting both the ordinary and the environmental interference functions with a model structure calculated using the reverse Monte Carlo simulation technique. The twomore » rust components were found to be the network structure formed by FeO{sub 6} octahedral units, the network structure itself deviating from the ideal case. The present results also suggest that the structural analysis method using anomalous X-ray scattering and the reverse Monte Carlo technique is very successful in determining the atomic-scale structure of rusts formed on the steel surfaces.« less

Reverse phase protein arrays in signaling pathways: a data integration perspective

PubMed Central

Creighton, Chad J; Huang, Shixia

2015-01-01

The reverse phase protein array (RPPA) data platform provides expression data for a prespecified set of proteins, across a set of tissue or cell line samples. Being able to measure either total proteins or posttranslationally modified proteins, even ones present at lower abundances, RPPA represents an excellent way to capture the state of key signaling transduction pathways in normal or diseased cells. RPPA data can be combined with those of other molecular profiling platforms, in order to obtain a more complete molecular picture of the cell. This review offers perspective on the use of RPPA as a component of integrative molecular analysis, using recent case examples from The Cancer Genome Altas consortium, showing how RPPA may provide additional insight into cancer besides what other data platforms may provide. There also exists a clear need for effective visualization approaches to RPPA-based proteomic results; this was highlighted by the recent challenge, put forth by the HPN-DREAM consortium, to develop visualization methods for a highly complex RPPA dataset involving many cancer cell lines, stimuli, and inhibitors applied over time course. In this review, we put forth a number of general guidelines for effective visualization of complex molecular datasets, namely, showing the data, ordering data elements deliberately, enabling generalization, focusing on relevant specifics, and putting things into context. We give examples of how these principles can be utilized in visualizing the intrinsic subtypes of breast cancer and in meaningfully displaying the entire HPN-DREAM RPPA dataset within a single page. PMID:26185419

Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography.

PubMed

Hau Fung Cheung, Rodney; Morrison, Paul D; Small, Darryl M; Marriott, Philip J

2008-12-05

A single enzyme treatment with alpha-amylase, prior to the quantification of added folic acid (FA) in fortified instant fried Asian noodles with analysis performed by capillary zone electrophoresis (CZE) and reversed-phase high performance liquid chromatography (RP-HPLC) with UV detection, is described. The method was validated and optimized for capillary electrophoresis (CE) with separation achieved using a 8 mM phosphate-12 mM borate run buffer with 5% MeOH at pH 9.5. FA was well separated from matrix components with nicotinic acid (NA) employed as an internal standard. In a comparative study, separation of FA was performed using HPLC with a mobile phase consisting of 27% MeOH (v/v) in aqueous potassium phosphate buffer (3.5 mM KH(2)PO(4) and 3.2 mM K(2)HPO(4)), pH 8.5, and containing 5 mM tetrabutylammonium dihydrogen phosphate as an ion-pairing agent. For both methods, excellent results were obtained for various analytical parameters including linearity, accuracy and precision. The limit of detection was calculated to be 2.2 mg/L for CE without sample stacking and 0.10 mg/L with high performance liquid chromatography (HPLC). Sample extraction involved homogenization and enzymatic extraction with alpha-amylase. Results indicated that FA was stable during four main stages of instant fried noodle manufacturing (dough crumbs, cut sheets, steaming and frying).

N-arachidonoyl--serine is neuroprotective after traumatic brain injury by reducing apoptosis

PubMed Central

Cohen-Yeshurun, Ayelet; Trembovler, Victoria; Alexandrovich, Alexander; Ryberg, Erik; Greasley, Peter J; Mechoulam, Raphael; Shohami, Esther; Leker, Ronen R

2011-01-01

N-arachidonoyl--serine (AraS) is a brain component structurally related to the endocannabinoid family. We investigated the neuroprotective effects of AraS following closed head injury induced by weight drop onto the exposed fronto-parietal skull and the mechanisms involved. A single injection of AraS following injury led to a significant improvement in functional outcome, and to reduced edema and lesion volume compared with vehicle. Specific antagonists to CB2 receptors, transient receptor potential vanilloid 1 (TRPV1) or large conductance calcium-activated potassium (BK) channels reversed these effects. Specific binding assays did not indicate binding of AraS to the GPR55 cannabinoid receptor. N-arachidonoyl--serine blocked the attenuation in phosphorylated extracellular-signal-regulated kinase 1/2 (ERK) levels and led to an increase in pAkt in both the ipsilateral and contralateral cortices. Increased levels of the prosurvival factor Bcl-xL were evident 24 hours after injury in AraS-treated mice, followed by a 30% reduction in caspase-3 activity, measured 3 days after injury. Treatment with a CB2 antagonist, but not with a CB1 antagonist, reversed this effect. Our results suggest that administration of AraS leads to neuroprotection via ERK and Akt phosphorylation and induction of their downstream antiapoptotic pathways. These protective effects are related mostly to indirect signaling via the CB2R and TRPV1 channels but not through CB1 or GPR55 receptors. PMID:21505478

N-arachidonoyl-L-serine is neuroprotective after traumatic brain injury by reducing apoptosis.

PubMed

Cohen-Yeshurun, Ayelet; Trembovler, Victoria; Alexandrovich, Alexander; Ryberg, Erik; Greasley, Peter J; Mechoulam, Raphael; Shohami, Esther; Leker, Ronen R

2011-08-01

N-arachidonoyl-L-serine (AraS) is a brain component structurally related to the endocannabinoid family. We investigated the neuroprotective effects of AraS following closed head injury induced by weight drop onto the exposed fronto-parietal skull and the mechanisms involved. A single injection of AraS following injury led to a significant improvement in functional outcome, and to reduced edema and lesion volume compared with vehicle. Specific antagonists to CB2 receptors, transient receptor potential vanilloid 1 (TRPV1) or large conductance calcium-activated potassium (BK) channels reversed these effects. Specific binding assays did not indicate binding of AraS to the GPR55 cannabinoid receptor. N-arachidonoyl-L-serine blocked the attenuation in phosphorylated extracellular-signal-regulated kinase 1/2 (ERK) levels and led to an increase in pAkt in both the ipsilateral and contralateral cortices. Increased levels of the prosurvival factor Bcl-xL were evident 24 hours after injury in AraS-treated mice, followed by a 30% reduction in caspase-3 activity, measured 3 days after injury. Treatment with a CB2 antagonist, but not with a CB1 antagonist, reversed this effect. Our results suggest that administration of AraS leads to neuroprotection via ERK and Akt phosphorylation and induction of their downstream antiapoptotic pathways. These protective effects are related mostly to indirect signaling via the CB2R and TRPV1 channels but not through CB1 or GPR55 receptors.

Analysis of quaternary ammonium and phosphonium ionic liquids by reversed-phase high-performance liquid chromatography with charged aerosol detection and unified calibration.

PubMed

Stojanovic, Anja; Lämmerhofer, Michael; Kogelnig, Daniel; Schiesel, Simone; Sturm, Martin; Galanski, Markus; Krachler, Regina; Keppler, Bernhard K; Lindner, Wolfgang

2008-10-31

Several hydrophobic ionic liquids (ILs) based on long-chain aliphatic ammonium- and phosphonium cations and selected aromatic anions were analyzed by reversed-phase high-performance liquid chromatography (RP-HPLC) employing trifluoroacetic acid as ion-pairing additive to the acetonitrile-containing mobile phase and adopting a step-gradient elution mode. The coupling of charged aerosol detection (CAD) for the non-chromophoric aliphatic cations with diode array detection (DAD) for the aromatic anions allowed their simultaneous analysis in a set of new ILs derived from either tricaprylmethylammonium chloride (Aliquat 336) and trihexyltetradecylphosphonium chloride as precursors. Aliquat 336 is a mix of ammonium cations with distinct aliphatic chain lengths. In the course of the studies it turned out that CAD generates an identical detection response for all the distinct aliphatic cations. Due to lack of single component standards of the individual Aliquat 336 cation species, a unified calibration function was established for the quantitative analysis of the quaternary ammonium cations of the ILs. The developed method was validated according to ICH guidelines, which confirmed the validity of the unified calibration. The application of the method revealed molar ratios of cation to anion close to 1 indicating a quantitative exchange of the chloride ions of the precursors by the various aromatic anions in the course of the synthesis of new ILs. Anomalies of CAD observed for the detection of some aromatic anions (thiosalicylate and benzoate) are discussed.

Comparison of reverse transcription-quantitative polymerase chain reaction methods and platforms for single cell gene expression analysis.

PubMed

Fox, Bridget C; Devonshire, Alison S; Baradez, Marc-Olivier; Marshall, Damian; Foy, Carole A

2012-08-15

Single cell gene expression analysis can provide insights into development and disease progression by profiling individual cellular responses as opposed to reporting the global average of a population. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) is the "gold standard" for the quantification of gene expression levels; however, the technical performance of kits and platforms aimed at single cell analysis has not been fully defined in terms of sensitivity and assay comparability. We compared three kits using purification columns (PicoPure) or direct lysis (CellsDirect and Cells-to-CT) combined with a one- or two-step RT-qPCR approach using dilutions of cells and RNA standards to the single cell level. Single cell-level messenger RNA (mRNA) analysis was possible using all three methods, although the precision, linearity, and effect of lysis buffer and cell background differed depending on the approach used. The impact of using a microfluidic qPCR platform versus a standard instrument was investigated for potential variability introduced by preamplification of template or scaling down of the qPCR to nanoliter volumes using laser-dissected single cell samples. The two approaches were found to be comparable. These studies show that accurate gene expression analysis is achievable at the single cell level and highlight the importance of well-validated experimental procedures for low-level mRNA analysis. Copyright © 2012 Elsevier Inc. All rights reserved.

Flow reversal and thermal limit in a heated rectangular channel

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

Cheng, L.Y.; Tichler, P.R.; Yang, B.W.

The thermal limit in a vertical rectangular channel was determined in a series of experiments whereby the internal coolant underwent a change in flow direction from forced downflow to upward natural circulation. The tests were designed to simulate the flow reversal transient in the High Flux Beam Reactor. A number of parameters were varied in the flow reversal experiments to examine their effects on the thermal limit. Among the parameters varied were the rate of flow coastdown, inlet subcooling, water level in the upper plenum, bypass ratio (ratio of initial flow through the heated section to initial flow through themore » bypass orifice), and single- verses double-sided heating.« less