Chemical-Rheological Evaluation of the Short-Term and Long-Term Effectiveness of Binder Rejuvenators

Many previous studies have investigated how rejuvenators affect/alter mechanical/chemical characteristics of aged binders. However, it has not been actively examined how the rejuvenated binders will perform for the next round of service after the rejuvenation was made. A better understanding of the short-term and long-term effect of rejuvenating agents in RAP blended asphalt mixtures is necessary to achieve more appropriate selection and use of rejuvenating agents

Magnetic field and pressure effects on charge density wave, superconducting, and magnetic states in Lu5_5Ir4_4Si10_{10} and Er5_5Ir4_4Si10_{10}

We have studied the charge-density-wave (CDW) state for the superconducting Lu$_5$Ir$_4$Si$_{10}$ and the antiferromagnetic Er$_5$Ir$_4$Si$_{10}$ as variables of temperature, magnetic field, and hydrostatic pressure. For Lu$_5$Ir$_4$Si$_{10}$, the application of pressure strongly suppresses the CDW phase but weakly enhances the superconducting phase. For Er$_5$Ir$_4$Si$_{10}$, the incommensurate CDW state is pressure independent and the commensurate CDW state strongly depends on the pressure, whereas the antiferromagnetic ordering is slightly depressed by applying pressure. In addition, Er$_5$Ir$_4$Si$_{10}$ shows negative magnetoresistance at low temperatures, compared with the positive magnetoresistance of Lu$_5$Ir$_4$Si$_{10}$.Comment: 12 pages, including 6 figure

N\'eel transition, spin fluctuations, and pseudogap in underdoped cuprates by a Lorentz invariant four-fermion model in 2+1 dimensions

We show that the N\'eel transition and spin fluctuations near the N\'eel transition in planar cuprates can be described by an SU(2) invariant relativistic four-fermion model in 2+1 dimensions. Features of the pseudogap phenomenon are naturally described by the appearance of an anomalous dimension for the spinon propagator.Comment: 5 pages, 2 figures (revtex4). Final revised and corrected versio

Dissolution in a field

We study the dissolution of a solid by continuous injection of reactive ``acid'' particles at a single point, with the reactive particles undergoing biased diffusion in the dissolved region. When acid encounters the substrate material, both an acid particle and a unit of the material disappear. We find that the lengths of the dissolved cavity parallel and perpendicular to the bias grow as t^{2/(d+1)} and t^{1/(d+1)}, respectively, in d-dimensions, while the number of reactive particles within the cavity grows as t^{2/(d+1)}. We also obtain the exact density profile of the reactive particles and the relation between this profile and the motion of the dissolution boundary. The extension to variable acid strength is also discussed.Comment: 6 pages, 6 figures, 2-column format, for submission to PR

Strong Discontinuities in the Complex Photonic Band Structure of Transmission Metallic Gratings

Complex photonic band structures (CPBS) of transmission metallic gratings with rectangular slits are shown to exhibit strong discontinuities that are not evidenced in the usual energetic band structures. These discontinuities are located on Wood's anomalies and reveal unambiguously two different types of resonances, which are identified as horizontal and vertical surface-plasmon resonances. Spectral position and width of peaks in the transmission spectrum can be directly extracted from CPBS for both kinds of resonances.Comment: 4 pages, 4 figures, REVTeX version

Current-Use Pesticides in New Zealand Streams: Comparing Results From Grab Samples and Three Types of Passive Samplers

New Zealand uses more than a ton of pesticides each year; many of these are mobile, relatively persistent, and can make their way into waterways. While considerable effort goes into monitoring nutrients in agricultural streams and programs exist to monitor pesticides in groundwater, very little is known about pesticide detection frequencies, concentrations, or their potential impacts in New Zealand streams. We used the ‘Polar Organic Chemical Integrative Sampler’ (POCIS) approach and grab water sampling to survey pesticide concentrations in 36 agricultural streams in Waikato, Canterbury, Otago and Southland during a period of stable stream flows in Austral summer 2017/18. We employed a new approach for calculating site-specific POCIS sampling rates. We also tested two novel passive samplers designed to reduce the effects of hydrodynamic conditions on sampling rates: the ‘Organic-Diffusive Gradients in Thin Films’ (o-DGT) aquatic passive sampler and microporous polyethylene tubes (MPTs) filled with Strata-X sorbent. Multiple pesticides were found at most sites; two or more were detected at 78% of sites, three or more at 69% of sites, and four or more at 39% of sites. Chlorpyrifos concentrations were the highest, with a maximum concentration of 180 ng/L. Concentrations of the other pesticides were generally below 20 ng/L. Mean concentrations of individual pesticides were not correlated with in-stream nutrient concentrations. The majority of pesticides were detected most frequently in POCIS, presumably due to its higher sampling rate and the relatively low concentrations of these pesticides. In contrast, chlorpyrifos was most frequently detected in grab samples. Chlorpyrifos concentrations at two sites were above the 21-day chronic ‘No Observable Effect Concentration’ (NOEC) values for fish and another two sites had concentrations greater than 50% of the NOEC. Otherwise, concentrations were well-below NOEC values, but close to the New Zealand Environmental Exposure Limits in several cases

Removal of a single photon by adaptive absorption

We present a method to remove, using only linear optics, exactly one photon from a field-mode. This is achieved by putting the system in contact with an absorbing environment which is under continuous monitoring. A feedback mechanism then decouples the system from the environment as soon as the first photon is absorbed. We propose a possible scheme to implement this process and provide the theoretical tools to describe it

Theoretical study of the influence of the morphology in polymer-based devices functioning

It is well known that the morphology of polymer-based optoelectronic devices can influence their efficiency, since the ways that polymer chains pack inside the active layer can influence not only the charge transport but also the optic properties of the device. By using a mesoscopic model we carried out computer experiments to study the influence of the polymer morphology on the processes of charge injection, transport, recombination and collection by the electrodes opposite to those where the injection of bipolar charge carriers take place. Our results show that for polymer layers where the conjugated segments have perpendicular and random orientation relative to the electrodes surface, the competition between charge collection and charge recombination is affected when the average conjugation length of the polymer strands increase. This effect is more pronounced with the increase of the potential barrier at polymer/electrode interfaces that limit charge injection and increase charge collection. For these molecular arrangements the intra-molecular charge transport plays a major role in device performance, being this effect negligible when the polymer molecules have their axis parallel to the electrodes. Although the polymer morphology modelled in this work is far from real, we believe that our model can give some insights on the role of the microstructure on the functioning of polymer-based devices.European Community Fund (FEDER)Fundação para a Ciência e a Tecnologia (FCT) – Programa Operacional “Ciência , Tecnologia, Inovação” – POCTI/CTM/41574/2001, CONC-REEQ/443/EEI/2005 e SFRH/BD/22143/200

Vacuum structure of Toroidal Carbon Nanotubes

Low energy excitations in carbon nanotubes can be described by an effective field theory of two components spinor. It is pointed out that the chiral anomaly in 1+1 dimensions should be observed in a metallic toroidal carbon nanotube on a planar geometry with varying magnetic field. We propose an experimental setup for studying this quantum effect. We also analyze the vacuum structure of the metallic toroidal carbon nanotube including the Coulomb interactions and discuss some effects of external charges on the vacuum.Comment: 10 pages, 11 figure

Quantum spin pumping with adiabatically modulated magnetic barrier's

A quantum pump device involving magnetic barriers produced by the deposition of ferro magnetic stripes on hetero-structure's is investigated. The device for dc- transport does not provide spin-polarized currents, but in the adiabatic regime, when one modulates two independent parameters of this device, spin-up and spin-down electrons are driven in opposite directions, with the net result being that a finite net spin current is transported with negligible charge current. We also analyze our proposed device for inelastic-scattering and spin-orbit scattering. Strong spin-orbit scattering and more so inelastic scattering have a somewhat detrimental effect on spin/charge ratio especially in the strong pumping regime. Further we show our pump to be almost noiseless, implying an optimal quantum spin pump.Comment: 14 pages, 9 figures. Manuscript revised with additional new material on spin-orbit scattering and inelastic scattering. Further new additions on noiseless pumping and analytical results with distinction between weak and strong pumping regimes. Accepted for publication in Physical Review