Hydrogen-Bond Symmetrization of δ-AlOOH

The δ-AIOOH can transport water into the deep mantle along cold subducting slab geothenn. We investigate the hydrogen-bond symmetrization behavior of δ-AIOOH under the relevant pressure-temperature condition of the lower mantle using ab initio molecular dynamics(AID). The static symmetrization pressure of 30.0 GPa can be reduced to 17.0 GPa at 300 K by finite-temperature(T) statistics, closer to the experimental observation of-10.0 GPa. The symmetrization pressure obtained by MD simulation is related to T by P(GPa) = 13.9(GPa) +0.01(GPa/K) × T(K). We conclude that δ-AIOOH in the lower mantle exists with symmetric hydrogen bond from its birthplace, or someplace slightly deeper, to the core-mantle boundary(CATB) along cold subducting slab geotherm. The bulk modulus decreases with T and increases anomalously upon symmetrization: K_o(GPa) =181(GPa)-0.013(GPa/K) × T(K) for δ-AIOOH with asymmetric hydrogen bond, and K_o(GPa) = 216(GPa)-0.013(GPa/K) × T(K) for δ-AIOOH with symmetric hydrogen bond. Our results provide an important insight into the existent form and properties of δ-AIOOH in the lower mantle.     

Optical response of a δ-layer capacitor

The fabrication of two δ-layers of opposite polarity in a semiconductor constitutes a capacitor. The charge on each "plate" may be modified by photogenerating carriers to screen the dopant ions, which alters the field between them. This has the effect of changing the transition energies between confined states in the structure, which results in a substantial (60 meV) blue shift, which may be utilised in a modulator structure. These effects have been investigated using steady-state and time-resolved photoluminescence, in conjunction with band modelling.     

Parity operator and quantization of δ-functions

In the Weyl quantization scheme, the -function at the origin of phase space corresponds to the parity operator. The quantization of a functionf() on phase space is the operator f(/2)W()dM, whereM is the parity andW() the Weyl operator.     

High-precision measurements of δ2H, δ18O and δ17O in water with the aid of cavity ring-down laser spectroscopy

A thorough evaluation of measurement uncertainty together with control of short-term and long-term precision of measurements should be a basis of any successful quality assurance/quality control (QA/QC) strategy aimed at maintaining a high quality of the analytical process. Here we present the results of a comprehensive assessment of the analytical performance of a Picarro L2140-i CRDS laser spectrometer analysing δ²H, δ¹⁸O and δ¹⁷O in water. The assessment is based on results obtained during 15 months of continuous operation of this instrument (February 2017 to May 2018). The short-term precision of measured and derived quantities was 0.11, 0.036, 0.028, 0.23 ‰ and 11 per meg, for δ²H, δ¹⁸O, δ¹⁷O, d-excess and Δ¹⁷O, respectively, and is comparable to the precision reported by the manufacturer. The long-term precision of the L2140-i, defined as standard uncertainty of the time series of 153 analyses of a laboratory standard conducted throughout 15 months, was roughly two times lower (0.24, 0.053, 0.038, 0.37 ‰ and 21 per meg, for δ²H, δ¹⁸O, δ¹⁷O, d-excess and Δ¹⁷O). In-depth assessment of the measurement uncertainty of a single analysis revealed that assigned uncertainty of the calibration standards is an important component of the uncertainty budget, especially in case of δ²H analysis.     

Products of distributions and collision of a δ-wave with a δ′-wave in a turbulent model

We study the possibility of collision of a δ-wave with a stationary δ′-wave in a model ruled by equation f (t)u _t+[u²?β(x?γ(t))u]_x = 0, where f, β and γ are given real functions and u = u(x, t) is the state variable. We adopt a solution concept which is a consistent extension of the classical solution concept. This concept is defined in the setting of a distributional product, which is not constructed by approximation processes. By a convenient choice of f, β and γ, we are able to distinguish three distinct dynamics for that collision, to which correspond phenomena of solitonic behaviour, scattering, and merging. Also, as a particular case, taking f = 2 and β = 0 we prove that the referred collision is impossible to arise in the setting of the inviscid Burgers equation. To show how this framework can be applied to other physical models, we included several results already obtained.     

Temperature dependence of elastic constants in δ-Pu

It is shown that the variation of the bulk and shear moduli in δ-Pu in a temperature range of 300–500 K is due to the phonon redistribution between different vibrational modes caused by the dispersion of the Grüneisen coefficients (phonon viscosity). The constants of interaction of the high-frequency acoustic modes with a long-wavelength deformation induced by an ultrasonic wave are estimated.     

The self-consistent calculation of Si δ-doped GaAs structures

In this study, we report results of a self-consistent calculation obtained for the sub-band structure of Si δ-doped GaAs material by using a new alternative method. We will discuss the influence of the δ-doping concentration and the δ-layerthickness on the sub-band structure for a non-uniform distribution, which is taken as different from the known Gaussian distribution. The confining potential, the sub-band energies, the sub-band occupations, and the Fermi energy have been calculated by solving the Schr?dinger and Poisson equations by using the Airy functions self-consistently. Received: 4 December 2000 / Accepted: 31 January 2001 / Published online: 26 April 2001     

Photoluminescence lineshape features of carbon δ-doped GaAs heterostructures

Photoluminescence lineshape properties of quasi-two-dimensional electron systems in setback δ-doped GaAs heterostructures are studied at liquid helium temperature. Contributions from the ground and the first excited two-dimensional subband are clearly observed. A simple fit to the lineshape including broadening demonstrates that there is an exponential low-energy tail associated with the ground subband. No such tail is observed for the first excited subband. The fit precisely reveals the subband bottom energies, the Fermi energy, the electron temperature and the recombination intensities. A self-consistent calculation of subband properties including the potential contribution of the setback δ-doping reproduces well the subband properties and the recombination intensities.     

Accuracy and precision of a laser-spectroscopy approach to the analysis of δ2H and δ18O in human urine

The isotope ratio analysis of body water often involves large sample numbers and lengthy sample processing. Here we demonstrate the ability of isotope ratio infrared spectroscopy (IRIS) to rapidly and accurately analyse the isotope ratios of water in urine. We analysed water extracted from human urine using traditional isotope ratio mass spectrometry (IRMS) and compared those values with IRIS-analysed extracted water and un-extracted urine. Regression analyses for δ²H and δ¹⁸O values between (1) extracted water analysed via IRMS and IRIS and (2) urine and extracted water analysed via IRIS were significant (R ²=0.99). These results indicate that cryogenic distillation of urine was not required for an accurate estimate of the isotopic composition of urine when using IRIS.     

Accuracy and precision of a laser-spectroscopy approach to the analysis of δ²H and δ¹⁸O in human urine

The isotope ratio analysis of body water often involves large sample numbers and lengthy sample processing. Here we demonstrate the ability of isotope ratio infrared spectroscopy (IRIS) to rapidly and accurately analyse the isotope ratios of water in urine. We analysed water extracted from human urine using traditional isotope ratio mass spectrometry (IRMS) and compared those values with IRIS-analysed extracted water and un-extracted urine. Regression analyses for δ2H and δ1?O values between (1) extracted water analysed via IRMS and IRIS and (2) urine and extracted water analysed via IRIS were significant (R2=0.99). These results indicate that cryogenic distillation of urine was not required for an accurate estimate of the isotopic composition of urine when using IRIS.     

A generalization of the one-dimensional δ-function Bose gas

The one-dimensional boson gas with -function interaction is modified to include arbitrary pseudopotential interaction. The system is shown to be solvable by the Bethe Ansatz for certain classes of pseudopotential.     

The Effect of Diet Quality on δ13C and δ15N in the Tissues of Locusts,Locusta migratoria L

Abstract

Locust nymphs were raised from hatching to adult locusts on either seedling wheat (C₃) or maize (C₄), to determine whether relative enrichments/depletions of ¹⁵N and ¹³C within body tissues are influenced by diet. The maize contained less hexose sugars and protein per gram than wheat.

The isotopic spacing between the food and the whole insect was found to differ between the two diets. The lower quality maize diet showed an overall +5.1‰ enrichment in δ¹⁵N compared to + 2.8‰ for wheat, possibly due to increased fractionation due to protein recycling.

The maize diet resulted in increased depletion in lipid and trehalose and depletion in chitin relative to diet. The results for both δ¹⁵N and δ¹³C suggest that substrate recycling was occurring on the low quality maize diet. Therefore diet quality determines the enrichment/depletion in δ¹⁵N and δ¹³C within organisms.     

On the possibility of a spiral spin ordering of the adsorbed-oxygen δ-phase

The existence of possible magnetic structures of the graphite-adsorbed oxygen monolayer δ-phase is predicted. It is shown that taking the exchange interaction of next-nearest molecules into account results in a spiral magnetic structure if the dipole intermolecular interaction is sufficiently small. The δ-phase magnetic structure corresponds to correlated chains of antiferromagnetically ordered spins directed perpendicular to the layer plane.     

Determination of δ2H and δ18O in saline oil-associated waters: the question of simple vacuum distillation of water samples prior to isotopic analyses

The paper deals with analytical and procedural aspects of δ¹⁸O and δ²H determination in saline oil-associated waters. The main objective of the study was to show experimentally the qualitative and quantitative applicability of the simple vacuum distillation of saline oil-associated waters while routine procedures of water isotopic analyses are applied. Additionally, two standard off-line techniques of δ²H determination in water – the zinc and the chromium method – have been compared. Each time a typical isotope salt effect has been tracked on the Dead Sea water. The results clearly show that application of the simple vacuum distillation improve the accuracy and reproducibility of δ²H determinations, especially in chromium off-line technique which appeared to be more sensitive to water salinity. The simple vacuum distillation does not improve the quality of δ¹⁸O determinations in the range of water salinities studied. Its application to high concentrated brines (for example, Dead Sea water) decreases the time of equilibration but still propagate the isotopic error connected with low water activity (in the case of ¹⁸O/¹⁶O ratio) and the incomplete water extraction from the remaining salts (in the case of ²H/¹H ratio); in consequence, its time-consuming application seems to be baseless.     

Integrability and PT-Symmetry of N-Body Systems with Spin-Coupling δ-Interactions

We study the PT-symmetric boundary conditions for "spin"-related -interactions and the corresponding integrability for both bosonic and fermionic many-body systems. The spectra and bound states are discussed in detail for 1/2-spin particle systems.     

Quantum effects of potential fluctuations in GaAs δ-doping superlattices

The electronic and optical properties of δ-doping n-i-p-i superlattices are strongly influenced by the random distribution of donors and acceptors within the doping layers. A Monte-Carlo method is applied to investigate the resulting potential fluctuations and local changes of energy levels and wavefunctions. We study disorder effects on the density of states, the capacitance and the intraband absorption coefficient as a function of excitation level. In addition, the luminescence spectra are calculated and compared to electroluminescence measurements. Excellent agreement is achieved without using any fitting parameters, if the local wavefunction shrinkage of the tail states is included. While contributions of different subbands cannot be resolved in the luminescence, the simulation of conduction band (CB) intraband absorption confirms that this is possible using resonant Raman scattering.     

On the two-photon width of the δ(980)

The two-photon width of the δ(980) is evaluated using three-point function sum rules which are able to predict accurately the anomalous π⁰ → γ and non-anomalous δ → ηπ decay rates. The prediction, though smaller than previous results based on vector meson dominance, is still higher than the present Crystal Ball data. An analysis of the three-point function with one-gluon exchange cannot support the previous successful explanation of the data within the four-quark scheme.     

Effects of pressure and/or magnetism on superconductivity of δ-MoN single crystal

Effects of pressure and/or magnetism on the critical superconducting temperature(Tc)ofδ-Mo N single crystal were investigated using a Maglab system.Theδ-Mo N single crystal was synthesized at extreme conditions of high pressure and high temperature.The carrier density ofδ-Mo N single crystal as a function of applied pressure was determined using Hall coefficient measurement.