Theoretical Investigations of EPR g Factors in Tetrahedral Compounds

Complete high-order perturbation formulas are established in ZnSe:Ti²⁺, CdTe:Ti²⁺, and ZnSe:V³⁺ crystals, based not only on the contributions of the spin-orbit coupling effect of the central ion and the ligands, but also on that of the charge-transfer levels. The electron paramagnetic resonance (EPR) g-factors are calculated from the formulas and the calculated values of the EPR g-factors agree well with the experimental ones. The contribution rate of the charge-transfer levels (|Δg ^T /Δg ^F |) are 10.1 %, 7.6 %, and 24.9 % for ZnSe:Ti²⁺, CdTe:Ti²⁺, and ZnSe:V³⁺ crystals, respectively.     

Thermal modeling of roadway embankments over permafrost

Thermal degradation of permafrost beneath embankments is an on-going problem in highway design. In recent years, engineers with the Alaska Department of Transportation and Public Facilities have used a commercially available, two-dimensional finite element model to determine the embankment's effect on the thermal regime of the foundation soils; however, the modeling was done with historic air temperature data and input parameters derived from the literature, rather than site-specific data. Temperatures and soil properties were measured at two different research sites in Alaska to compare against model results. A sensitivity analysis of certain input parameters was conducted on the model for each site. Analysis of the model results indicates that the most critical input parameter is the surface boundary condition, which is separated into air temperature and modifying n-factors. Using site-specific air temperature data resulted in models that closely matched the measured soil temperatures, and either matched or overestimated the active layer depths. If used for design purposes, the thermal modeling would result in a more conservative embankment construction, which is favorable if a warming climate is considered.     

Preparation and crystal structure of a new cesium iron niobium oxide: Cs3Fe0.44Nb5.56O16

Single crystals of a new niobium oxide, Cs₃Fe_0.44Nb_5.56O₁₆ were prepared at 1200°C under an Ar atmosphere. This compound has the orthorhombic space group Pbcm and Z=4. The lattice parameters were a=10.470(3), b=7.514(4) and c=21.312(3) Å, and the final R-factors were R=0.027 and R_w=0.033 for 1085 unique reflections. The crystal structure is a three-dimensional tunnel structure built up by edge- and corner-sharing NbO₆ octahedra and (Fe,Nb)O₄ tetrahedra and cesium atoms are located in two types of tunnels. The Cs⁺ ion in the tunnels was ion-exchanged partially with Rb⁺ ion.     

A study on the thermal expansion characteristics of Inconel-82® filler wire by high temperature X-ray diffraction

The lattice parameter (a) change with respect to temperature (T) has been measured by high temperature X-ray diffraction (HT-XRD) technique for Inconel-82®¹ filler wire used in the TIG welding of a dissimilar joint involving Inconel-600® and commercially pure iron. By taking proper precautions to minimise the temperature gradient across the sample thickness, and by suitably calibrating the shift in 2θ produced as a result of sample buckling at high temperatures, we could obtain fairly reliable estimates of lattice parameter in the temperature range 300–1200 K. The lattice parameter and the coefficient of mean linear thermal expansion at 300 K, have been found to be 3.546(2)×10⁻¹⁰ m and 11.03×10⁻⁶ K⁻¹, respectively.     

Two-point calibration of standard capsule platinum resistance thermometers for the range 13.81 K to 273.15 K

A method of calibrating a standard capsule platinum resistance thermometer (prt) over the range 13.81 K to 273.15 K is described. Measurements of the resistance of the prt are needed at only two fixed points, the boiling point of He⁴ (4.2 K) and the ice-point (273.15 K), both of which are easy to realize. For a prt with a residual resistance ratio (R_{4.2 K}/R_{273.15 K}) of less than 4 × 10^?4, the method provides a calibration on ipts 68 with an uncertainty of 20 mK over the entire range 13.81 K to 273.15 K. For prts with residual resistance ratios between 4 × 10^?4 and 7 × 10^?4, the calibration uncertainty is 75 mK from 13.81 K to 40 K and 20 mK from 40 K to 273.15 K.     

Analysis of the First Spectrum of Ruthenium (Ru I)

The analysis of the first spectrum of ruthenium has been extended with the aid of digital computers. A total of 105 even and 206 odd levels are listed with observed Landé g-factors for 54 even and 148 odd levels. A complete list of approximately 3,400 classified lines in the range 2013 to 11484 A is presented. The ionization limit calculated from a two member series is 59410 cm⁻¹ or 7.364 v.     

Two-parameter characterization of elastic-plastic crack front fields: Surface cracked plates under tensile loading

In this paper the J-Q two-parameter characterization of elastic-plastic crack front fields is examined for surface cracked plates under uniaxial and biaxial tensile loadings. Extensive three-dimensional elastic-plastic finite element analyses were performed for semi-elliptical surface cracks in a finite thickness plate, under remote uniaxial and biaxial tension loading conditions. Surface cracks with aspect ratios a/c = 0.2, 1.0 and relative depths a/t = 0.2, 0.6 were investigated. The loading levels cover from small-scale to large-scale yielding. In topological planes perpendicular to the crack fronts, the crack stress fields were obtained. In order to facilitate the determination of Q-factors, modified boundary layer analyses were also conducted. The J-Q two-parameter approach was then used in characterizing the elastic-plastic crack front stress fields along these 3D crack fronts. Complete distributions of the J-integral and Q-factors for a wide range of loading conditions were obtained. It is found that the J-Q characterization provides good estimate for the constraint loss for crack front stress fields. It is also shown that for medium load levels, reasonable agreements are achieved between the T-stress based Q-factors and the Q-factors obtained from finite element analysis. These results are suitable for elastic-plastic fracture mechanics analysis of surface cracked plates.     

Neptunium speciation in soils

The relative content of ²³⁷Np in the water-soluble form depends on the soil type and decreases in the following order: sandy loam soil > soddy podzolic soil > chernozem (black soil). The fraction of the most mobile forms of ²³⁷Np decreases with an increase in the content of organic carbon in soils. The major fraction of ²³⁷Np is associated with the fulvic acid (FA) group (90.3 and 71.0% of the total neptunium content for soddy podzolic soil and chernozem, respectively), with 8.6 and 18.7% of ²³⁷Np, respectively, associated with the humic acid (HA) group. In the FA group, the major fraction of ²³⁷Np is associated with low-molecular-weight organic compounds and with FA, free or bonded mainly with relatively mobile hydroxides of Fe, Al, Mn, etc. (R₂O₃·nH₂O) (fractions 1a and 1).     

DEA based on strongly efficient and inefficient frontiers and its application on port efficiency measurement

Data envelopment analysis (DEA) is a non-parametric analytical methodology widely used in efficiency measurement of decision making units (DMUs). Conventionally, after identifying the efficient frontier, each DMU is compared to this frontier and classified as efficient or inefficient. This paper first introduces the strongly efficient frontier (SEF) and strongly inefficient frontier (SIF), and then proposes several models to calculate various distances between DMUs and both frontiers. Specifically, the distances considered in this paper include: (1) both the distance to SEF and the distance to SIF, where the former reveals a unit’s potential opportunity to become a best performer while the latter reveals its potential risk to become a worst performer, and (2) both the closest distance and the farthest distance to frontiers, which may provide different valuable benchmarking information for units. Subsequently, based on these distances, eight efficiency indices are suggested to rank DMUs. Due to different distances adopted in these indices, the efficiency of units can be evaluated from diverse perspectives with different indices employed. In addition, all units can be fully ranked by these indices. The efficiency of 24 major Asian container ports is analyzed with our study, where the potential opportunities and potential crises of these ports are revealed and some new insights about their efficiency are provided.     

Dynamics of radiostrontium leaching from radioactively contaminated floodplain soils of the Yenisei River

Gleyzation-mediated leaching of radiostrontium from floodplain soils of the Krasnoyarsk Mining and Chemical Combine (MCC) activity zone [Atamanovskii Island (front part), Oseredysh Island (front part), and Berezovyi Island (rear part)] is studied with model systems. Leaching of radiostrontium from waterlogged soils is analyzed in terms of the model of anaerobic biosolubilization of gel films. The leaching of radiostrontium is found to correlate with that of iron, confirming the cosolubilization model. Addition of glucose (0.5%) as a stimulant for growth of iron-reducing microorganisms increases the dynamic coefficient of radiostrontium leaching, particularly in soils with lower organic matter content. The model experiments showed that the radiostrontium leaching rate from floodplain soil is higher by 2–3 orders of magnitude than that of radio-cesium, suggesting the possibility of escape of radiostrontium from the floodplain of the Yenisei River with the intrasoil runoff. This conclusion is supported by the experimental data on the ⁹⁰Sr/¹³⁷Cs ratio in the floodplain of the Yenisei River downstream of MCC (0.01–0.1).     

North–South divide: contrasting impacts of climate change on crop yields in Scotland and England

Effects of climate change on productivity of agricultural crops in relation to diseases that attack them are difficult to predict because they are complex and nonlinear. To investigate these crop–disease–climate interactions, UKCIP02 scenarios predicting UK temperature and rainfall under high- and low-CO₂ emission scenarios for the 2020s and 2050s were combined with a crop-simulation model predicting yield of fungicide-treated winter oilseed rape and with a weather-based regression model predicting severity of phoma stem canker epidemics. The combination of climate scenarios and crop model predicted that climate change will increase yield of fungicide-treated oilseed rape crops in Scotland by up to 0.5 t ha⁻¹ (15%). In contrast, in southern England the combination of climate scenarios, crop, disease and yield loss models predicted that climate change will increase yield losses from phoma stem canker epidemics to up to 50 per cent (1.5 t ha⁻¹) and greatly decrease yield of untreated winter oilseed rape. The size of losses is predicted to be greater for winter oilseed rape cultivars that are susceptible than for those that are resistant to the phoma stem canker pathogen Leptosphaeria maculans. Such predictions illustrate the unexpected, contrasting impacts of aspects of climate change on crop–disease interactions in agricultural systems in different regions.     

The Spectrum of Singly Ionized Atomic Iodine (I ii)

The I ii spectrum has been excited in electrodeless lamps and photographed from 655 A to 11084 A. Wavelengths and estimated intensities are given for almost 2,400 lines. A revision and extension of the earlier analyses of this spectrum has increased the number of known even levels from 43 to 124, and the number of odd levels from 55 to 190. New g_J-factors are given for 46 levels, and the previous designations of 40 levels are changed. Improved measurements in the vacuum ultraviolet region give a correction of 7.4 cm⁻¹ to be subtracted from the values listed in Atomic Energy Levels, Vol. 3 (1958), for all levels above the ground configuration. The approximately 1,800 classified lines now include all of the strongest lines. The ¹S₀ of the ground configuration 5s²5p⁴ has been found, and this configuration has been fitted to intermediate coupling theory. Magnetic dipole transitions between levels of the ground configuration, ³P₂–¹D₂ (7282 A) and ³P₁–¹S₀ (4460 A), have been observed and their nature confirmed by the Zeeman effect. The line 5p^{4 3}P₂–¹D₂ shows hyperfine structure which is in approximate agreement with a theoretical calculation of the expected structure. New levels have been found for almost all higher configurations. All previously known series have been extended and new ones found. From one of the new series, 5p3(4S°)5−12g5G6°, the principal ionization energy for I ii (154304 ±1 cm⁻¹) has been derived. The results of the analysis are compared with theoretical expectations in a number of cases.     

Effects of field-manure applications on stratified 17β-estradiol concentrations

The occurrence of the manure-borne estrogen, 17β-estradiol (E2), was investigated in laboratory and field soils. In the laboratory, E2 was applied to soil to simulate concentrations found in swine (Sus scrofa domestica) manure (5000 ng L⁻¹). The aqueous-extracted E2 dissipated in the soil by 98% within 1 h and was not significantly different from background concentrations (18 ng L⁻¹) for the duration of the experiment (64 h). In the field study, soil cores were taken before and several dates after swine manure application. Equivalent porewater concentrations of water-extractable E2 were determined in 0.15-m increments down to the water table (0.70-2.00 m deep). The average frequency of detection for 168 samples was 38% (average = 40 ng L⁻¹ porewater equivalents). Eleven days after manure application there was no significant effect on E2 detection frequency or concentration. However, E2 concentrations significantly increased by 6 months after manure application, and appeared to be related to precipitation. Concentrations then returned to original levels by 17 months after manure application. Manure did not have an immediate effect on E2 occurrence due to the capacity of the soil to rapidly sorb E2. However, it appears that soil may act as a long-term reservoir for E2 in the environment, which may be periodically released through desorption.     

Vacuum Measurements of a Novel Micro-resonator Based on Tin Whiskers Performed at mK Temperatures

We present a method of preparation and preliminary vacuum measurements conducted at ～20 mK of a new type of micro-resonator based on Sn-whiskers. Sn-whiskers have ～1 μm radius and their length can be ～1–2 mm. As added benefit, the Sn-whiskers are mono-crystalline metal fibers with relatively smooth surface and being superconducting at low temperatures one may expect their high Q-factors.     

Efficiency modeling of solidification/stabilization of multi-metal contaminated industrial soil using cement and additives

In a laboratory study, formulations of 15% (w/w) of ordinary Portland cement (OPC), calcium aluminate cement (CAC) and pozzolanic cement (PC) and additives: plasticizers cementol delta ekstra (PCDE) and cementol antikorodin (PCA), polypropylene fibers (PPF), polyoxyethylene-sorbitan monooleate (Tween 80) and aqueous acrylic polymer dispersion (Akrimal) were used for solidification/stabilization (S/S) of soils from an industrial brownfield contaminated with up to 157, 32,175, 44,074, 7614, 253 and 7085 mg kg⁻¹ of Cd, Pb, Zn, Cu, Ni and As, respectively. Soils formed solid monoliths with all cementitious formulations tested, with a maximum mechanical strength of 12 N mm⁻² achieved after S/S with CAC + PCA. To assess the S/S efficiency of the used formulations for multi-element contaminated soils, we propose an empirical model in which data on equilibrium leaching of toxic elements into deionized water and TCLP (toxicity characteristic leaching procedure) solution and the mass transfer of elements from soil monoliths were weighed against the relative potential hazard of the particular toxic element. Based on the model calculation, the most efficient S/S formulation was CAC + Akrimal, which reduced soil leachability of Cd, Pb, Zn, Cu, Ni and As into deionized water below the limit of quantification and into TCLP solution by up to 55, 185, 8750, 214, 4.7 and 1.2-times, respectively; and the mass transfer of elements from soil monoliths by up to 740, 746, 104,000, 4.7, 343 and 181-times, respectively.     

Beam wander and M2-factor of partially coherent electromagnetic hollow Gaussian beam propagating through non-Kolmogorov turbulence

Propagation formulae for M²-factor and beam wander of partially coherent electromagnetic hollow Gaussian (PCEHG) beam in non-Kolmogorov turbulence are derived based on the extended Huygens–Fresnel principle and the second-order moments of the Wigner distribution function. Our results indicate that the normalized M²-factors of PCEHG beam with larger beam order, waist width, inner scale of turbulence, the generalized exponent parameter, and smaller transverse coherent widths, outer scale of turbulence, the generalized structure parameter are less affected by the turbulence. The root mean square beam wander and relative beam wander are more obvious for PCEHG beam with smaller beam order, larger inner and outer scales of turbulence, exponent parameter, transverse coherent widths, and the generalized structure parameter. What is more, the beam wander properties of PCEHG beam in non-Kolmogorov turbulence are very different from M²-factor and spreading properties of beam in turbulence.     

Resonantly pumped 1.645 μm single longitudinal mode Er:YAG laser with intracavity etalons

We report on a 1.645 μm single longitudinal mode Er:YAG laser that was resonantly pumped by a 1.532 μm fiber laser, using intracavity etalons to generate single longitudinal mode operation. We obtained 0.749 W single longitudinal mode output power at 1.645 μm from an Er:YAG laser with two intracavity etalons. The M²-factors of the Er:YAG laser were 1.041 and 1.068 in the x and y directions, respectively.     

Enhanced variant designs and characteristics of the microstructured solid-state neutron detector

Silicon diodes with large aspect ratio perforated microstructures backfilled with ⁶LiF show a dramatic increase in neutron detection efficiency beyond that of conventional thin-film coated planar devices. Described in this work are advancements in the technology with increased microstructure depths and detector stacking methods to increase thermal neutron detection efficiency. The highest efficiency devices thus far have delivered over 37% intrinsic thermal neutron detection efficiency by device-coupling stacking methods. The detectors operate as conformally diffused pn junction diodes with 1 cm² square-area. Two individual devices were mounted back-to-back with counting electronics coupling the detectors together into a single dual-detector device. The solid-state silicon device operated at 3 V and utilized simple signal amplification and counting electronic components. The intrinsic detection efficiency for normal-incident 0.0253 eV neutrons was found by calibrating against a ³He proportional counter and a ⁶LiF thin-film planar semiconductor device. This work is a part of on-going research to develop solid-state semiconductor neutron detectors with high detection efficiencies and uniform angular responses.     

Spin-orbit coupling of sp2 nanocarbons and magnetism of fullerene C60 in view of spin peculiarities of unrestricted Hartree–Fock solution

The paper presents the first application of unrestricted Hartree–Fock formalism to the consideration of spin-orbit coupling (SOC) of open-shell systems in general and sp² nanocarbons in particular. The SOC parameters determination is exhibited on the example of stretched ethylene. g-Factor determination addresses fullerene C₆₀ due to its peculiar “paradiamagnetic” behavior at low temperature characterized by a set of local spins with different g-factors. The approach application has allowed not only to suggest a reliable explanation of the factor variability but to supplement it by a quantitative agreement with experimental data.     

Application of Metaheuristic Algorithms for Optimizing Longitudinal Square Porous Fins

The objectives of this study involve the optimization of longitudinal porous fins of square cross-section using metaheuristic algorithms. A generalized nonlinear ordinary differential equation is derived using Darcy and Fourier’s laws in the energy balance around a control volume and is solved numerically using RFK 45 method. The temperature of the base surface is higher than the fin surface, and the fin tip is kept adiabatic or cooled by convection heat transfer. The other pertinent parameters include Rayleigh number (100 ≤ Ra ≤ 10⁴), Darcy number, (10⁻⁴ ≤ Da ≤ 10⁻²), relative thermal conductivity ratio of solid phase to fluid (1000 ≤ k_r ≤ 8000), Nusselt number (10 ≤ Nu ≤ 100), porosity (0.1 ≤ φ ≤ 0.9). The impacts of these parameters on the entropy generation rate are investigated and optimized using metaheuristic algorithms. In computer science, metaheuristic algorithms are one of the most widely used techniques for optimization problems. In this research, three metaheuristic algorithms, including the firefly algorithm (FFA), particle swarm algorithm (PSO), and hybrid algorithm (FFA-PSO) are employed to examine the performance of square fins. It is demonstrated that FFA-PSO takes fewer iterations and less computational time to converge compared to other algorithms.