Influence of the intensity of gg irradiation on the photoluminescence of GaAs:Te

The influence of gg irradiation (⁶⁰Co) of various intensities (P _γ≈1.7−7.5kGR/h) on the photoluminescence of GaAs:Te single crystals [n ₀=(1.2–2.3×10¹⁸ cm⁻³] is investigated. Together with the known photoluminescence impurity bands (hν _max≈1.2 eV and/or hν _max≈1.35 eV) and edge band (hν _max≈1.51 eV), new bands are also observed in the spectra at hν _max≈1.3 eV and hν _max≈1.48 eV. The observed effects are attributed to radiation-stimulated ordering of the donor impurity and deep impurity centers. Fiz. Tekh. Poluprovodn. 32, 38–39 (January 1998)     

Sludge Pre-Treatment through Ozone Application: Alternative Sludge Reuse Possibilities for Recirculating Aquaculture System Optimization

Recirculating Aquaculture Systems (RAS) reduce water consumption by efficient filtration to maintain appropriate levels of accumulating compounds and sludge. Sludge is mechanically separated by drum filters and disposed of to the detriment of overall system water budgets. Dissolved nitrogen compounds are reduced via nitrification–denitrification filters, requiring commercial external carbon sources. The reuse of sludge after ozone pre-treatment may represent the next step in RAS optimization. The present study analyzes the content of sludge from RAS and tests ozonation as a pre-treatment for recycling as carbon source. The dissociative effect of ozone and the physicochemical changes due to ozonation lead to a significant increase in soluble carbon availability. Predominantly long-chain fatty acid (FA) (saturated and unsaturated) with 16 and 18 carbon atoms independently of the treatment were found in the profiles. Saturated FA concentrations in solution increased after 20, 40, and 60 min ozonation. The solid content of the sludge was practically unaffected by ozonation in terms of FA profile: only saturated FA slightly increases after 40 min treatment. The implications of these findings for denitrifying bacteria are discussed.

Abbreviations: Recirculating Aquaculture Systems (RAS); Advanced Oxidation Processes (AOPs)     

Statistical Models and Adequacy Validation for Optical Quantum State Tomography with Quadrature Measurements

Mutually complementary quadrature quantum measurements are analyzed and a new method to formulate statistical models of quantum states is proposed. The method is based on the root approach to quantum measurements and includes a procedure for approximating quantum states with reduced finite dimensional models. The efficiency of the proposed approach is demonstrated using numerical experiments. This approach is aimed at achieving the highest possible precision in multiphoton quantum state tomography.     

Occurrence and risk assessment of mycotoxins,acrylamide, and furan in Latvian beer

This work reports data on the occurrence of nine mycotoxins and two food processing contaminants – acrylamide and furan – in a total of 100 beers produced in Latvia. Mycotoxins were detected by high-performance liquid chromatography (HPLC) coupled with time-of-flight mass spectrometry, acrylamide by HPLC coupled with quadrupole-Orbitrap mass spectrometry, and furan by headspace gas chromatography-mass spectrometry. The most frequently occurring mycotoxins were HT-2 and deoxynivalenol (DON), which were detected in 52% and 51% of the analysed samples. The highest content was observed for DON, reaching the maximum of 248 µg kg^?1. Furan was ubiquitous, and 74% of the samples contained acrylamide. In terms of the estimated exposure, the biggest potential risk was identified for HT-2 representing more than 11% of tolerable weekly intake. The margin of exposure approach indicated the exposure to furan through beer as significant, this parameter being close to the critical limit.     

Photochromic and Magnetic Nanocomposites Based on Epoxy and Polycarbonate Matrices

Surface functionalization methods of magnetic nanoparticles by photochromic ligands linking covalently with bifunctional alkoxysilanes as spacer bridges are developed. The epoxy nanocomposite films based on the mixture of epoxy oligomer ED-20 and aliphatic epoxy oligomer DEG-1 containing the modified magnetite nanoparticles are obtained via polycondensation. The polycarbonate nanocomposite films are obtained via evaporation of dichloromethane in which polycarbonate and nanoparticles were previously dispersed. The structure, composition, photochromic and magnetic properties of obtained nanocomposites are studied.     

Study of photon statistics using a compound Poisson distribution and quadrature measurements

This paper describes the model of a compound Poisson distribution for photon statistics with regard to their bunching in Fock states, thermal states, and others. The method of generating functions is used to calculate the probability distributions, moments, and correlation functions. The parameters of conditional states arising from the subtraction of photons by splitting the beam are determined. The problem of state reconstruction with regard to quadrature quantum measurements is considered. The study is aimed at developing high-precision methods for generating and controlling optical quantum states.     

Morphometry and Stiffness of Red Blood Cells—Signatures of Neurodegenerative Diseases and Aging

Human red blood cells (RBCs) are unique cells with the remarkable ability to deform, which is crucial for their oxygen transport function, and which can be significantly altered under pathophysiological conditions. Here we performed ultrastructural analysis of RBCs as a peripheral cell model, looking for specific signatures of the neurodegenerative pathologies (NDDs)—Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Alzheimer’s disease (AD), utilizing atomic force (AFM) and conventional optical (OM) microscopy. We found significant differences in the morphology and stiffness of RBCs isolated from patients with the selected NDDs and those from healthy individuals. Neurodegenerative pathologies’ RBCs are characterized by a reduced abundance of biconcave discoid shape, lower surface roughness and a higher Young’s modulus, compared to healthy cells. Although reduced, the biconcave is still the predominant shape in ALS and AD cells, while the morphology of PD is dominated by crenate cells. The features of RBCs underwent a marked aging-induced transformation, which followed different aging pathways for NDDs and normal healthy states. It was found that the diameter, height and volume of the different cell shape types have different values for NDDs and healthy cells. Common and specific morphological signatures of the NDDs were identified.     

ET based conductors with different behavior of resistivity along and across conducting layers

A series of novel bis(ethylenedithio)tetrathiafulvalene (ET) based radical cation salts with tetrahedral [HgBr₄]^2? and [CdBr₄]^2? dianions of (ET)₄MBr₄(solvent) stoichiometry (M = Hg, Cd; solvent = C₆H₅X or 1,2-C₆H₄X₂, X = Cl, Br) has been prepared. Crystal structures of θ-(ET)₄HgBr₄(1,2-C₆H₄X₂) (X = Cl, Br) were found to involve conducting ET radical cation layers of the θ-type packing and insulating layers consisting of [HgBr₄]^2? anions and solvent molecules. The donor stacking directions of the neighboring conducting layers are perpendicular to each other.Depending on salt composition, intralayer electrical resistivity of θ-(ET)₄MBr₄(solvent) showed metal-like behavior down to temperatures varying within 4.3–100 K range. Electrical resistivity perpendicular to the layers revealed nonmetallic behavior. The study of magnetoresistance of θ-(ET)₄HgBr₄(1,2-C₆H₄Cl₂) revealed Shubnikov-de Haas oscillations in fields up to 15 T with the only frequency F = 900 T. The θ-(ET)₄MBr₄(C₆H₄Cl₂) M = Hg, Cd compounds are the first ET-based conductors which show metallic behavior of conductivity in layers and semiconducting behavior across layers down to 4.3 K.