Determining the Characteristics of Cosmic-Radiation Nuclei in the Sileye Experiment on Board the Mir Orbital Station

An algorithm for reconstructing the characteristics (charge, mass, and energy) of cosmic-radiation nuclei with 20- to 200-MeV/nucleon energies is described. The detector is a telescope of three two-coordinate planes with two 1-mm-thick iron filters inserted between them. Each plane is composed of two strip silicon detectors with 3.6-mm-wide orthogonally oriented strips, an effective area of 6 × 6 cm², and a thickness of 380 m. The algorithm for reconstructing the nuclei characteristics is based on the analysis of how the specific ionization losses change as the nuclei pass through the filter material. The results of the Monte Carlo simulation are presented for the energy dependence of the telescope acceptance and the energy deposited in the detectors by different nuclei in view of the detector calibration on the nuclear beams of the accelerator. The mass resolution of the telescope is 30, 12, and 5% for He, N, and Al nuclei, respectively. The energy resolution, which is 20%, is much the same for all nuclei.     

Design, implementation, and characterization of an optical power supply spot-array generator for a four-stage free-space optical backplane

The design and implementation of a robust, scalable, and modular optical power supply spot-array generator for a modulator-based free-space optical backplane demonstrator is presented. Four arrays of 8 x 4 spots with 6.47-mum radii (at 1/e(2) points) pitched at 125 mum in the vertical direction and 250 mum in the horizontal were required to provide the light for the optical interconnect. Tight system tolerances demanded careful optical design, robust optomechanics, and effective alignment techniques. Issues such as spot-array generation, polarization, power efficiency, and power uniformity are discussed. Characterization results are presented.     

Reservoir Management Using a Network Flow Optimization Model Considering Quadratic Convex Cost Functions on Arcs

The allocation of water resources between different users is a hard task for water managers because they must deal with conflicting objectives. The main objective is to obtain the most accurate distribution of the resource and the associated circulating flows through the system. This induces the need for a river basin optimization model that provides optimized results. This article presents a network flow optimization model to solve the water allocation problem in water resource systems. Managing a water system consists in providing water in the right proportion, at the right place and at the right time. Time expanded network allows to take into consideration the temporal dimension in the decision making. Since linear cost functions on arcs present many limitations and are not realistic, quadratic convex cost functions on arcs are considered here. The optimization algorithm developed herein extend the cycle canceling algorithm developed for linear cost functions. The methodology is applied to manage the three reservoirs of La Haute-Vilaine’s watershed located in the north west of France to protect a three vulnerable areas from flooding. The results obtained with the algorithm are compared to a reference scenario which consists in considering reservoirs transparent. The results show that the algorithm succeeds in managing the reservoir releases efficiently and keeps the flow rates below the vigilance flow in the vulnerable areas.     

Modelling the Performance of Single-Photon Counting Kinetic Inductance Detectors

We present the first published results of near-infrared single-photon detection in aluminium lumped element kinetic inductance detectors (LEKIDs). Using aluminium as a well-understood material that follows conventional superconductor theory, we discuss and validate a model that describes the energy-resolving performance of a LEKID to single-photon absorption events. We also discuss data analysis techniques used to extract single-photon detections from noisy data. We measure an energy resolution of 662 meV for a 1550 nm photon source which is in close agreement to our model predictions for this non-optimised device limited by generation–recombination noise.     

3D XFEM investigation of the plasticity effect on fatigue propagation under thermo-mechanical loading

The aim of this paper is to propose a computation strategy for fatigue propagation simulation of a crack by taking into account the plasticity. Feulvarch et al. (Comput Methods Appl Mech Eng 361: 112805, 2020) recently proposed a first XFEM formulation capable of overcoming the volumetric locking phenomenon due to plastic incompressibility in 3D. This formulation is here applied to quadratic elements for the mode I propagation of a crack in a valve structure submitted to cyclic thermo-mechanical loading. A simulation strategy is proposed where it is not necessary to compute all the cycles and thus the complete plastic history. This is of great interest because it avoids the treatment of the possible closing of the crack and uses the conventional J-integral. The application reveals the interest of taking plasticity into account for the propagation accuracy.

     

Synthesis of alkyloxy (di)alkylamino propanols, hydroxy alkyloxy (di)alkylamino propanols, and the dimer compounds for use as fuel additives

Alkyl glycidyl ethers and bis glycidyl ethers, synthesized in a heterogeneous weakly hydrous medium, were condensed with primary or secondary amines to obtain 3-alkyloxy propanolamines or bis alkyloxy propanolamines in a regioselective manner. The compounds were characterized by conventional spectroscopic methods, and complete nuclear magnetic resonance data are given. Their high-temperature stability, their good emulsifying power, their oxidation, and corrosion inhibition make these compounds suitable for solubilizing ethanol-diesel fuel blends.     

Cloud condensation nuclei from the activation with ozone of soot particles sampled from a kerosene diffusion flame

Due to the exponential increase in aircraft traffic in recent decades, the role of soot particles emitted by aircraft engines on the radiative forcing needs to be addressed, and especially their interaction with clouds has to be better understood and quantified. In this work, we investigate the hygroscopic properties of fresh and aged soot sampled on line in a kerosene flame. The activated fraction (F_a) of size selected soot is measured by means of a variable supersaturation condensation nucleus counter at several heights above the burner (HAB), thereby probing soot particles with different residence times in the flame, i.e., different degrees of maturity. In order to simulate atmospheric aging, the activity of soot as cloud condensation nuclei is measured as a function of ozone exposure. We show that fresh soot is hydrophobic (F_a～0), while F_a increases when soot is exposed to ozone. The measurements depend on the HAB at which soot particles are sampled showing that activation of soot particles is related to their chemical composition. This study brings new results on the link between atmospheric aging of soot and its hygroscopic properties, which is of great interest for understanding the role of soot in the cloud formation.

Copyright © 2018 American Association for Aerosol Research     

Wide varieties of cationic nanoparticles induce defects in supported lipid bilayers

Nanoparticles with widely varying physical properties and origins (spherical versus irregular, synthetic versus biological, organic versus inorganic, flexible versus rigid, small versus large) have been previously noted to translocate across the cell plasma membrane. We have employed atomic force microscopy to determine if the physical disruption of lipid membranes, formation of holes and/or thinned regions, is a common mechanism of interaction between these nanoparticles and lipids. It was found that a wide variety of nanoparticles, including a cell penetrating peptide (MSI-78), a protein (TAT), polycationic polymers (PAMAM dendrimers, pentanol-core PAMAM dendrons, polyethyleneimine, and diethylaminoethyl-dextran), and two inorganic particles (Au-NH2, SiO2-NH2), can induce disruption, including the formation of holes, membrane thinning, and/or membrane erosion, in supported lipid bilayers.     

Carbon nanotubes in macrophages: imaging and chemical analysis by X-ray fluorescence microscopy

X-ray fluorescence microscopy (microXRF) is applied for the first time to study macrophages exposed to unpurified and purified single-walled (SW) and multiwalled (MW) carbon nanotubes (CNT). Investigating chemical elemental distributions allows one to (i) image nanotube localization within a cell and (ii) detect chemical modification of the cell after CNT internalization. An excess of calcium is detected for cells exposed to unpurified SWCNT and MWCNT and related toxicological assays are discussed.     

Identification of ritual blood in African artifacts using TOF-SIMS and synchrotron radiation microspectroscopies

A new protocol is implemented to demonstrate the presence of blood in the patina of African art objects from Mali. Divided into three steps, the protocol first consists in demonstrating the presence of proteins and localizing them in the sample's cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry (microFT-IR). In a second time, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence (microXRF) and X-ray absorption near-edge microspectroscopy (microXANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment. This permits us thus to demonstrate that iron is indeed linked with proteins and not with mineral phases of the sample. Coupled with the ritual context of the objects, this constitutes a proof of the use of blood. Thanks to this protocol, which has the major advantage of avoiding false positive results, the presence of blood has been demonstrated in seven out of the eight studied samples.