The Role of Excitation Photons Energy in the Photoinduced Carrier Dynamics in InGaAs/InAlAs Superlattice Heterostructures

Technical Physics Letters - The influence of excitation photons energy on the relaxation times of photoexcited carriers is studied. The involved relaxation mechanisms are evaluated and the...     

Phase and amplitude comparison between experiment and calculation of ultrabroad-band pulses generated in a taper fiber

Using a cross-correlation frequency-resolved optical gating apparatus, the phases and amplitudes of ultrabroad-band optical pulses from a taper fiber have been measured for various input pulse peak powers. The measured waveforms have been compared with calculated waveforms using a finite-difference in the frequency domain method, in which no envelope approximations were used and the variation of the taper shape was taken into account. Excellent agreement between the measured and the calculated waveforms was obtained when the additional dispersion of a normal fiber and an objective was considered.     

Trace elements in human transitory milk. Variation caused by biological attributes of mother and infant

Multielement analysis was performed on human milk collected on 5-9-d postpartum from 51 Japanese females using inductively coupled plasma (ICP) mass spectrometry (MS), ICP atomic emission spectrometry (ICP-AES) and fluorometry. Thirty-one elements were detected by these analytical methods in milk. Twelve elements (Na, Mg, P, S, K, Ca, Cu, Zn, Se, Sr, Rb, and Mo) were detected in all of the samples. Al, Cs, and Ba were the elements detected by ICP-MS in more than half of the samples. Multiple regression analysis extracted biological attributes of mother and infant, such as maternal stature, maternal wt, or infant's birth wt, as statistically significant factors contributing to the variation in elemental concentration in milk. However, the rates of contribution were small in all cases. It was concluded that the biological attributes of mother and infant examined in this study were not the major factors that contribute to elemental variation in human milk.     

Zinc Dialkyl Phosphate (<Emphasis Type="Bold">ZP</Emphasis>) as an Anti-Wear Additive: Comparison with <Emphasis Type="Bold">ZDDP</Emphasis>

In this study, we are interested in the anti-wear properties of zinc dialkyl phosphate additive (ZP) in comparison with ‘classical’ zinc dialkyldithiophosphate (ZDDP). Friction tests were performed on a reciprocating tribometer using both ball-on-flat and cylinder-on-flat configurations under a Hertzian contact pressure of 0.9 GPa. Experiments were carried out as a function of temperature (25 and 100 °C), sliding speed (25, 50 and 100 mm/s) and additives concentrations. Ball wear scar diameters as well as friction coefficient were measured. In order to better understand the anti-wear mechanisms of these additives, friction tests were followed by surface analyses such as AES (Auger Electron Spectroscopy) and XPS (X-Ray Photoelectron Spectroscopy). Transmission Electron Microscopy (TEM) observations of the ZDDP and ZP tribofilms were also carried out to visualise the generated layers. The anti-wear capability of ZP molecule is discussed.     

Time-alternating method based on single-sideband holography with half-zone-plate processing for the enlargement of viewing zones

The single-sideband method of holography, as is well known, cuts off beams that come from conjugate images for holograms produced in the Fraunhofer region and from objects with no phase components. The single-sideband method with half-zone-plate processing is also effective in the Fresnel region for beams from an object that has phase components. However, this method restricts the viewing zone to a narrow range. We propose a method to improve this restriction by time-alternating switching of hologram patterns and a spatial filter set on the focal plane of a reconstruction lens.     

Preparation of β-FeSi2 substrates by molten salt method

Large-sized β-FeSi₂ substrates were successfully prepared for the first time from the silicide bulk crystal grown by the molten salt method. The structural, electrical and optical properties of the as-grown β-FeSi₂ bulk crystals were also investigated. The crystal is single phase β-FeSi₂, and polycrystalline with no preferable growth crystallographic orientations. It was also determined that the β-FeSi₂ shows a p-type conduction, and the hole concentration and the Hall mobility at room temperature were about 10¹⁷ cm^− 3 and 10 cm²/Vs, respectively. In addition, the PL emission around 0.8 eV was realized from the β-FeSi₂ bulk crystal. This simple vacuum-free growth technique of β-FeSi₂ and the large-sized substrate preparation procedure encourage us to develop future silicide-based electronics.     

Polarization-Insensitive Monolithic 40-Gbps SOA–MZI Wavelength Converter With Narrow Active Waveguides

A polarization-insensitive monolithic 40-Gbps semiconductor optical amplifier (SOA)-Mach-Zehnder interferometer wavelength converter has been developed. Based on the photon-electron rate equation, we optimized the dimensions of the waveguide structure to maximize the field confinement in the active layer. An InGaAsP active layer with narrow SOA waveguide effectively enables polarization-insensitive high-speed wavelength conversion. High-precision wafer processing technique enabled the fabrication of submicrometer-wide active waveguides with low current leakage. Input waveguide arrays were fabricated at intervals of 25 mum and mounted in a module with two-lens aspherical lens optics. The 40-Gbps nonreturn-to-zero wavelength conversion experiment demonstrates a clear eye opening over full C-band operation     

Effect of salting-out agents on nitric acid distribution between liquid and vapor in the course of evaporation of nitric acid radioactive waste

The database on the influence of concentrations of salting-out agents with different cation valence (Li⁺, Na⁺, K⁺, Cs⁺, NH₄⁺, Mg2+, Ca²⁺, Cu²⁺, Zn²⁺, Al³⁺, Fe³⁺, La³⁺, Pu⁴⁺, UO₂²⁺ nitrates) and of H₂SO₄ on the HNO₃ distribution between liquid and vapor at atmospheric pressure was verified and expanded by performing equilibrium evaporation experiments in an evaporator without reflux with circulation of the bottoms. This equilibrium can be described by the equation \(\log {\kern 1pt} {\alpha _H} = - 2.35 + 2\log \;{X_{\Sigma N{O_3}}}\) (where \({X_{\Sigma N{O_3}}}\) is the total concentration of nitrate ions in aqueous solution), taking into account partial binding of water due to hydration of the salting-out agent and apparent hydrolysis of polyvalent cations, and also incomplete dissociation of sulfuric acid. The suggested model is valid at \({X_{\Sigma N{O_3}}}\) from 3 to 16 M (azeotrope); at \({X_{\Sigma N{O_3}}}{\text{ < }}\;3\), Raoult’s law is observed (α_H = const), which is confirmed by a number of examples. In this model, the additivity of the properties of the salting- out agents, taking into account the concentration of “free” water, is assumed, which allows calculation of the composition of the bottoms and distillate when evaporating waste of any composition from radiochemical plants.     

Extraction of Eu and Am with extractants based on carbamoyl phosphine oxide (CMPO)

The possibility of adding an HDEHP solution as solubilizer to a CMPO-diluent system was examined. In the presence of Zr in the organic phase, mixed complexes are formed in this case. They exert no appreciable effect on the dependence of the Eu extraction on the acid concentration but noticeably increase the extractant capacity.     

Classification of mineral deposits according to the degree of radon release

A classification of mineral deposits according to the degree of radiation hazard for workers in prospecting sections and mining-enrichment combines and the public in adjoining development territories is substantiated on the basis of NRB-99. Four categories of radiation hazardous deposits are identified. The radiation hazard is considered separately for the public, workers in underground sections, and workers in surface production and processing operations. 4 tables, 8 references. A. A. Logachev All-Russia Scientific-Research Institute of Prospecting Geophysics. Translated from Atomnaya énergiya, Vol. 88, No. 6, pp. 438–445, June, 2000.