Emergency water supplies for transient populations

Emergency water supplies for transient population

Thermogravimetric analysis of carbon black and engine soot - Towards a more robust oil analysis method

This work examined the thermal behaviour of diesel engine produced soot and commercial carbon black using thermogravimetric analysis (TGA). It was found that during TGA analysis of the carbon matrices (at a temperature range commonly used for soot-in-oil content determination), a gradual mass loss occurred. This was attributed to pyrolysis effects and combustion processes occurring due to poor hydrodynamic design of some commercial thermobalances. This process resulted in a significant mass loss of the carbon during TGA. This finding may strongly effect soot-in-oil analysis conducted using current methods. Experiments were conducted using a range of soot-in-oil mixtures according to the widely used thermogravimetric standard method ASTM 5967-08 which showed a significant underestimation of the soot content in the oil as a result of carbon mass loss due to combustion and/or pyrolysis effects. An improved oil analysis method is proposed which provides a significantly increased accuracy of soot determination in lubricant oils

drag forces in statistically stationary and homogeneous submerged granular flows

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African peasants on the move: turmoil between global dynamics, migration and food insecurity

This issue presents some of the publications resulting from the research project “African societies facing global dynamics: Turbulences between external intervention, migration, and food insecurity” [Dynamics]1. The underlying idea was to investigate contemporary global dynamics faced by African societies, how they interact with internal processes of change and these societies’ responses to these pressures. The contributions address the key issues raised in the Dynamics research project in different ways. They focus on an analysis of migration (internal as well as international), agricultural transformation and food (in)security in different societies and locations. They also explore the links between them and their interrelations with global dynamics. The work was based on case studies conducted in Guinea-Bissau, São Tomé and Príncipe (STP), Cape Verde and Senegal. An additional contribution from Mozambique was also included as it addressed the central issues of the project. Although this research project in itself can only address a few aspects of this complex set of interactions and highlight some of the key issues at play in specific case studies, the project is part of a long-term investigation about the dynamics of change in African agrarian societies which contemplates a wider range of issues.info:eu-repo/semantics/publishedVersio

A microscopic mechanism of dielectric breakdown in SiO2 films: An insight from multi-scale modeling

Despite extensive experimental and theoretical studies, the atomistic mechanisms responsible for dielectric breakdown (BD) in amorphous (a)-SiO2 are still poorly understood. A number of qualitative physical models and mathematical formulations have been proposed over the years to explain experimentally observable statistical trends. However, these models do not provide clear insight into the physical origins of the BD process. Here we investigate the physical mechanisms responsible for dielectric breakdown in a-SiO2 using a multi-scale approach where the energetic parameters derived from a microscopic mechanism are used to predict the macroscopic degradation parameters of BD, i.e. time-dependent dielectric breakdown (TDDB) statistics, and its voltage dependence. Using this modeling framework, we demonstrate that trapping of two electrons at intrinsic structural precursors in a-SiO2 is responsible for a significant reduction of the activation energy for Si-O bond breaking. This results in a lower barrier for the formation of O vacancies and allows us to explain quantitatively the TDDB data reported in the literature for relatively thin (3-9nm) a-SiO2 oxide films

The influence of the copper content in grape must on alcoholic fermentation kinetics and wine quality. A survey on the performance of 50 commercial Active Dry Yeasts

The effects of copper on the viability and fermentative activity of 50 active dry yeasts purchased on the northern Italian market were studied, and revealed that Copper excess may cause massive death of yeast cells, leading to a significant delay in the start and progress of alcoholic fermentation. A two-log units reduction in cell viability was observed when copper content of musts was around 20 mg∙L-1. Despite this, the difference noted in the kinetics after 20 days' fermentation was lower than that observed 48 hours after in the grape must. An excess of copper in must affected also the composition of the produced wines. The increase in acetic acid and in the sulphur dioxide concentration, observed in wines made using grape must with a high copper concentration, raises serious doubts both regarding the possibility of obtaining good wines from these raw materials and in relation to the progress of subsequent steps of winemaking, such as malolactic fermentation. While it is an important tool in preventing vine diseases, copper must be used very carefully to avoid serious troubles during wine fermentation, even if some yeasts seem more suited to ferment musts containing up to 20-30 mg∙L-1 copper.

Tetrathiafulvalene based electroactive ligands and complexes: Synthesis, crystal structures and antifungal activity

The synthesis of two tetrathiafulvalene-appended pyridinehydrazone pyrimidine ligands, namely (Z)-4-(2-((5-([2,2′-bi(1,3-dithiolylidene)]-4-yl)pyridin-2-yl)methylene) hydrazinyl)-6-chloropyrimidine L1 and (Z)-4-(2-((6-([2,2′-bi(1,3-dithiolylidene)]-4-yl)pyridin-2-yl)methylene) hydrazinyl)-6-chloropyrimidine L2 is described. Ligand L1 was reacted with cobalt(II) to yield a cationic metal complex [Co(L1)2] while ligand L2 was reacted with zinc(II) to afford a neutral metal complex [ZnL2Cl2]. The crystal structure analysis of [Co(L1)2] indicate that Co(II) ion is coordinated by six nitrogen atoms from two perpendicular ligands while in [ZnL2Cl2], Zn(II) is coordinated by two chlorine atoms and three nitrogen atoms. The electrochemical behavior indicate that ligands L1 and L2 and the zinc(II) complex are suitable fort the preparation of crystalline radical cation salts. Finally the determination of MIC80 values against C. albicans, C. glabrata, C. parapsilosis, C. krusei and E. dermatitidis revealed that the cobalt(II) metal complex [Co(L1)2] is active against all the studied fungi

Multiscale modeling for application-oriented optimization of resistive random-access memory

Memristor-based neuromorphic systems have been proposed as a promising alternative to von Neumann computing architectures, which are currently challenged by the ever-increasing computational power required by modern artificial intelligence (AI) algorithms. The design and optimization of memristive devices for specific AI applications is thus of paramount importance, but still extremely complex, as many dierent physical mechanisms and their interactions have to be accounted for, which are, in many cases, not fully understood. The high complexity of the physical mechanisms involved and their partial comprehension are currently hampering the development of memristive devices and preventing their optimization. In this work, we tackle the application-oriented optimization of Resistive Random-Access Memory (RRAM) devices using a multiscale modeling platform. The considered platform includes all the involved physical mechanisms (i.e., charge transport and trapping, and ion generation, diusion, and recombination) and accounts for the 3D electric and temperature field in the device. Thanks to its multiscale nature, the modeling platform allows RRAM devices to be simulated and the microscopic physical mechanisms involved to be investigated, the device performance to be connected to the material's microscopic properties and geometries, the device electrical characteristics to be predicted, the effect of the forming conditions (i.e., temperature, compliance current, and voltage stress) on the device's performance and variability to be evaluated, the analog resistance switching to be optimized, and the device's reliability and failure causes to be investigated. The discussion of the presented simulation results provides useful insights for supporting the application-oriented optimization of RRAM technology according to specific AI applications, for the implementation of either non-volatile memories, deep neural networks, or spiking neural networks

Propionibacterium avidum infection following breast reduction: high morbidity from a low-virulence pathogen

Propionibacterium avidum is a common inhabitant of sebaceous glands, traditionally considered to be of low virulence and generally found on implanted foreign material. We report a rare case of P. avidum breast abscess, causing severe morbidity following breast reduction surgery. A 36-year-old woman presented with a non-painful wound discharge 3 weeks postoperatively, and was treated conservatively. She was readmitted 7 weeks postoperatively with a red and tender breast. A purulent discharging abscess was drained under ultrasound guidance. A 2-week intravenous course of amoxicillin-clavulanic acid, followed by oral replacement for a month resulted effective. Serial ultrasound imaging was useful in treatment decision-making. The infective potential of P. avidum may be underappreciated. Proximity of sutures to the axilla, tobacco smoking and the potential for resorbable sutures to host bacteria may predispose to infection, and should raise the clinician's awareness