Exact solution of kinetic analysis for thermally activated delayed fluorescence materials

Research at Kyushu, Kyoto and St Andrews Universities was supported by EPSRC and JSPS Core to Core grants (JSPS Core-to-core Program; EPSRC grant number EP/R035164/1). Authors are also grateful for financial support from the Program for Building Regional Innovation Ecosystems of the Ministry of Education, Culture, Sports, Science and Technology, Japan, JST ERATO Grant JPMJER1305, JSPS KAKENHI JP20H05840, and Kyulux Inc.The photophysical analysis of thermally activated delayed fluorescence (TADF) materials has become instrumental to providing insight into their stability and performance, which is not only relevant for organic light-emitting diodes (OLED), but also for other applications such as sensing, imaging and photocatalysis. Thus, a deeper understanding of the photophysics underpinning the TADF mechanism is required to push materials design further. Previously reported analyses in the literature of the kinetics of the various processes occurring in a TADF material rely on several a priori assumptions to estimate the rate constants for forward and reverse intersystem crossing (ISC and RISC, respectively). In this report, we demonstrate a method to determine these rate constants using a three-state model together with a steady-state approximation and, importantly, no additional assumptions. Further, we derive the exact rate equations, greatly facilitating a comparison of the TADF properties of structurally diverse emitters and providing a comprehensive understanding of the photophysics of these systems.PostprintPostprintPeer reviewe

Quantum key distribution using gaussian-modulated coherent states

Quantum continuous variables are being explored as an alternative means to implement quantum key distribution, which is usually based on single photon counting. The former approach is potentially advantageous because it should enable higher key distribution rates. Here we propose and experimentally demonstrate a quantum key distribution protocol based on the transmission of gaussian-modulated coherent states (consisting of laser pulses containing a few hundred photons) and shot-noise-limited homodyne detection; squeezed or entangled beams are not required. Complete secret key extraction is achieved using a reverse reconciliation technique followed by privacy amplification. The reverse reconciliation technique is in principle secure for any value of the line transmission, against gaussian individual attacks based on entanglement and quantum memories. Our table-top experiment yields a net key transmission rate of about 1.7 megabits per second for a loss-free line, and 75 kilobits per second for a line with losses of 3.1 dB. We anticipate that the scheme should remain effective for lines with higher losses, particularly because the present limitations are essentially technical, so that significant margin for improvement is available on both the hardware and software.Comment: 8 pages, 4 figure

On the equivalence of pairing correlations and intrinsic vortical currents in rotating nuclei

The present paper establishes a link between pairing correlations in rotating nuclei and collective vortical modes in the intrinsic frame. We show that the latter can be embodied by a simple S-type coupling a la Chandrasekhar between rotational and intrinsic vortical collective modes. This results from a comparison between the solutions of microscopic calculations within the HFB and the HF Routhian formalisms. The HF Routhian solutions are constrained to have the same Kelvin circulation expectation value as the HFB ones. It is shown in several mass regions, pairing regimes, and for various spin values that this procedure yields moments of inertia, angular velocities, and current distributions which are very similar within both formalisms. We finally present perspectives for further studies.Comment: 8 pages, 4 figures, submitted to Phys. Rev.

Time-odd components in the mean field of rotating superdeformed nuclei

Rotation-induced time-odd components in the nuclear mean field are analyzed using the Hartree-Fock cranking approach with effective interactions SIII, SkM*, and SkP. Identical dynamical moments ${{\cal J}^{(2)}}$ are obtained for pairs of superdeformed bands $^{151}$Tb(2)--$^{152}$Dy(1) and $^{150}$Gd(2)--$^{151}$Tb(1). The corresponding relative alignments strongly depend on which time-odd mean-field terms are taken into account in the Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include

Squeezing more from a quantum nondemolition measurement

We use a stable, 5 dB, amplitude squeezed source for a quantum nondomolition (QND) experiment. The performance of our QND system is enhanced by an electro-optic feedforward loop which improve,, the signal transfer efficiency. At best, we measure a total signal transfer of 1.81 and conditional variance of 0.55

PT-symmetric Solutions of Schrodinger Equation with position-dependent mass via Point Canonical Transformation

PT-symmetric solutions of Schrodinger equation are obtained for the Scarf and generalized harmonic oscillator potentials with the position-dependent mass. A general point canonical transformation is applied by using a free parameter. Three different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter.Comment: 13 page

Breeding programmes to improve male reproductive performance and efficiency of insemination dose production in paternal lines: feasibility and limitations

[EN] This paper aims at reviewing the current genetic knowledge of the issues related to the efficient use of bucks in artificial insemination (AI). Differences between lines have been found relevant in semen production and quality traits not necessarily related to their specialization as maternal or paternal lines. Accurate heritability estimates indicate that genetic selection for increasing semen production by improving male libido and reducing the number of rejected ejaculates may not be effective. However, total sperm produced per ejaculate appears to be as an interesting trait to select for, despite that genetic correlation between ejaculate volume and sperm concentration has not been yet accurately estimated. Semen pH has shown low to medium heritability estimates and a low coefficient of variation, therefore it is not advisable to attempt improvement by direct selection. In general, sperm motility traits have shown low heritabilities but, the rate of motile sperms per ejaculate has been considered as convenient to select for. Morphological characteristics of the spermatozoa have revealed as medium to highly heritable. There are evidences of high genetic correlations between sperm traits before and after freezing-thawing. There are few studies regarding the estimation of heterosis of seminal traits but results indicate important and favorable direct and maternal heterosis in crosses between maternal lines. However, this has not been confirmed in a cross between two paternal lines. Until now, attempts to find parametric or non-parametric functions to predict ejaculate fertility through seminal characteristics recorded in routinely evaluations have been very unsatisfactory. Hence, it may be necessary to find other semen quality markers, or to evaluate some of the currently used ones in a more precise manner or closer to the AI time in order to improve the ability to predict ejaculate fertility. Several seminal characteristics phenotypically correlated to male fertility, could be considered as potential traits to select for in order to genetically improving this trait. However, only the semen pH has been checked for this purpose, and a negative result has been obtained. Other traits can be studied in the future but bearing in mind that the required experiments will need large number of bucks for an accurate estimation of the genetic correlation of the trait with male fertility. This means that these experiments will be expensive and difficult to set up. The most common criterion to select paternal lines, average daily gain, seems not to be genetically correlated to male fertility and seminal traits. Thus, selection for average daily gain has no detrimental consequences on these traits, and a multi-trait selection, including growth rate and seminal traits directly related to an efficient AI semen dose production, is feasible in paternal lines. The male contribution to fertility after natural mating and after AI with semen doses with high concentration is negligible, but it has been found that, under more restrictive conditions of AI, male contributions to fertility and litter size are low but higher in magnitude than the ones obtained after natural mating. The genetic correlation between the female and male contributions to fertility has been found to be moderate to high and positive.This study was supported by the Generalitat Valenciana Research Programme (Prometeo 2009/125) and Spanish Research Projects (INIA RTA2005-00088-CO2; INIA RTA2008-00070-CO2; CICYT AGL2008-03274). Raquel Lavara was supported by a research grant from the Spanish Ministry of Education (MEC, FPU AP2007-03755) and Llibertat Tusell by a research grant from INIA.Piles, M.; Tusell, L.; Lavara García, R.; Baselga Izquierdo, M. (2013). Breeding programmes to improve male reproductive performance and efficiency of insemination dose production in paternal lines: feasibility and limitations. World Rabbit Science. 21(2):61-75. doi:10.4995/wrs.2013.1240SWORD617521

Search for CP Violation in the Decay Z -> b (b bar) g

About three million hadronic decays of the Z collected by ALEPH in the years 1991-1994 are used to search for anomalous CP violation beyond the Standard Model in the decay Z -> b \bar{b} g. The study is performed by analyzing angular correlations between the two quarks and the gluon in three-jet events and by measuring the differential two-jet rate. No signal of CP violation is found. For the combinations of anomalous CP violating couplings, ${\hat{h}}_b = {\hat{h}}_{Ab}g_{Vb}-{\hat{h}}_{Vb}g_{Ab}$ and $h^{\ast}_b = \sqrt{\hat{h}_{Vb}^{2}+\hat{h}_{Ab}^{2}}$, limits of \hat{h}_b < 0.59$and$h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st

c-Type Cytochrome-Dependent Formation of U(IV) Nanoparticles by Shewanella oneidensis

Modern approaches for bioremediation of radionuclide contaminated environments are based on the ability of microorganisms to effectively catalyze changes in the oxidation states of metals that in turn influence their solubility. Although microbial metal reduction has been identified as an effective means for immobilizing highly-soluble uranium(VI) complexes in situ, the biomolecular mechanisms of U(VI) reduction are not well understood. Here, we show that c-type cytochromes of a dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, are essential for the reduction of U(VI) and formation of extracelluar UO (2) nanoparticles. In particular, the outer membrane (OM) decaheme cytochrome MtrC (metal reduction), previously implicated in Mn(IV) and Fe(III) reduction, directly transferred electrons to U(VI). Additionally, deletions of mtrC and/or omcA significantly affected the in vivo U(VI) reduction rate relative to wild-type MR-1. Similar to the wild-type, the mutants accumulated UO (2) nanoparticles extracellularly to high densities in association with an extracellular polymeric substance (EPS). In wild-type cells, this UO (2)-EPS matrix exhibited glycocalyx-like properties and contained multiple elements of the OM, polysaccharide, and heme-containing proteins. Using a novel combination of methods including synchrotron-based X-ray fluorescence microscopy and high-resolution immune-electron microscopy, we demonstrate a close association of the extracellular UO (2) nanoparticles with MtrC and OmcA (outer membrane cytochrome). This is the first study to our knowledge to directly localize the OM-associated cytochromes with EPS, which contains biogenic UO (2) nanoparticles. In the environment, such association of UO (2) nanoparticles with biopolymers may exert a strong influence on subsequent behavior including susceptibility to oxidation by O (2) or transport in soils and sediments