Relationship between Micro-/Nano-Structure and Stress Development in TM-Doped Mg-Based Alloys Absorbing Hydrogen

2012 ◽  
Vol 194 ◽  
pp. 237-244 ◽  
Author(s):  
N.E. Skryabina ◽  
Vladimir M. Pinyugzhanin ◽  
Daniel Fruchart
Keyword(s):  
Hydrogen Absorption ◽  
Mechanical Parameters ◽  
Systematic Analysis ◽  
Nano Structure ◽  
Early Transition Metal ◽  
Crystallite Sizes ◽  
External Stresses ◽  
The Impact ◽  
Kinetics Of

In the most recent years, MgH2has attracted considerable attention for reversible hydrogen storage purposes because of a large 7.6 w% H-uptake, single plateau reaction at low pressure and abundance of metal. If the Mg ↔ H reactions take place at rather high temperature (> 300°C), the kinetic remains very low. However, early transition metal based additives (Ti, V, Nb...) improve dramatically the kinetics of hydrogen absorption/desorption, while having no essential impact on the reversible sorption capacity. Systematic analysis of many experimental data led to question chemical, physical, mechanical... parameters contributing significantly to improve the kinetics of absorption/desorption. Besides, results of theoretical and numerical computation enlighten the impact of structural and mechanical parameters owing to the local bonds of Mg/MgH2with of TM elements, in terms of total energy and electronic structure. More specifically, we found highly relevant to consider 1 - the impact of the crystallite sizes of Mg and the TM-phase, 2 - the role of internal and external stresses, as well as 3 - the role of texture on the kinetics of hydrogen absorption/desorption. Apart the previous considerations, we like to underline the role of specific TM in trapping intermediately hydrogen thus forming TMHxprior initiating the Mg ↔ MgH2nucleation process.

scholarly journals Solid-State Hydrogen Storage: Materials, Systems and the Relevance of a Gender Perspective

2021 ◽  
Author(s):  
Erika Michela Dematteis ◽  
Jussara Barale ◽  
Marta Corno ◽  
Alessandro Sciullo ◽  
Marcello Baricco ◽  
...  
Keyword(s):  
Solid State ◽  
Hydrogen Storage ◽  
Operating Conditions ◽  
Hydrogen Sorption ◽  
Enthalpy Of Reaction ◽  
Gender Perspective ◽  
The Social ◽  
The Impact ◽  
Kinetics Of

This paper aims at addressing the exploitation of solid-state carriers for hydrogen storage, with attention paid both to the technical aspects, through a wide review of the available integrated systems, and to the social aspects, through a preliminary overview of the connected impacts from a gender perspective. As for the technical perspective, carriers to be used for solid-state hydrogen storage for various applications can be classified into two classes: metal and complex hydrides. Related crystal structures and corresponding hydrogen sorption properties are reviewed and discussed. Fundamentals of thermodynamics of hydrogen sorption evidences the key role of the enthalpy of reaction, which determines the operating conditions (i.e. temperatures and pressures). In addition, it rules the heat to be removed from the tank during hydrogen absorption and to be delivered to the tank during hydrogen desorption. Suitable values for the enthalpy of hydrogen sorption reaction for operating conditions close to ambient (i.e. room temperature and 1-10 bar of hydrogen) are close to 30 kJ·molH2 1. The kinetics of hydrogen sorption reaction is strongly related to the microstructure and to the morphology (i.e. loose powder or pellets) of the carriers. Usually, kinetics of hydrogen sorption reaction is rather fast, and the thermal management of the tank is the rate determining step of the processes. As for the social perspective, various scenarios for the applications in different socio-economic contexts of solid-state hydrogen storage technologies are described. As it occurs with the exploitation of other renewables innovative technologies, a wide consideration of the social factors connected to these processes is needed to assess the extent to which a specific innovation might produce positive or negative impacts in the recipient socio-economic system and to explore the potential role of the social components and dynamics in fostering the diffusion of the innovation itself. Attention has been addressed to the gender perspective, in view of the enhancement of hydrogen-related energy storage systems, intended both in terms of the role of women in triggering the exploitation of hydrogen-based storage as well as to the impact of this innovation in their current conditions, at work and in daily life.

Influence of aluminum location on hydrogen sorption kinetics of magnesium-based materials

2014 ◽  
Vol 07 (03) ◽  
pp. 1450034 ◽  
Author(s):  
Shixue Zhou ◽  
Tonghuan Zhang ◽  
Naifei Wang ◽  
Tao Li ◽  
Haili Niu ◽  
...  
Keyword(s):  
Hydrogen Absorption ◽  
Particle Surface ◽  
Hydrogen Desorption ◽  
Sorption Kinetics ◽  
Al Alloy ◽  
Desorption Kinetics ◽  
Reactive Milling ◽  
Crystallite Sizes ◽  
Apparent Activation Energies ◽  
Kinetics Of

Hydrogen storage materials from Mg – Al alloy and Mg + Al mixture were prepared by reactive milling under H 2 atmosphere with carbonized anthracite as milling aid. The crystal structure of the materials and influence of Al location on hydrogen absorption/desorption kinetics were investigated. Results show that Mg partly got hydrided into β- MgH 2 and γ- MgH 2 during reactive milling. The average crystallite sizes of β- MgH 2 in the as-milled Mg – Al alloy and Mg + Al mixture were calculated by Scherrer equation to be 10 nm and 17 nm, respectively. In the process of hydrogen desorption, the catalytic ability of Al in Mg crystal lattice was not as effective as that on particle surface. The apparent activation energies for hydrogen desorption of the two materials were estimated by Kissinger equation to be 112.2 kJ/mol and 63.7 kJ/mol, respectively. Mg 17 Al 12 reacted with H 2 to convert into MgH 2 and elemental Al during static hydrogenation at 300°C. For the hydrogenated Mg + Al mixture, the obvious increase of crystallite size resulted in a low rate of hydrogen absorption and a high temperature for hydrogen desorption.

scholarly journals Effect of Surface Roughness on Aggregation of Polypeptide Chains: A Monte Carlo Study

Biomolecules ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 596
Author(s):  
Nguyen Truong Co ◽  
Mai Suan Li
Keyword(s):  
Surface Roughness ◽  
Self Assembly ◽  
Molecular Mechanisms ◽  
Monte Carlo Study ◽  
The Self ◽  
Living Organisms ◽  
Polypeptide Chains ◽  
The Impact ◽  
Kinetics Of

The self-assembly of amyloidogenic peptides and proteins into fibrillar structures has been intensively studied for several decades, because it seems to be associated with a number of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s disease. Therefore, understanding the molecular mechanisms of this phenomenon is important for identifying an effective therapy for the corresponding diseases. Protein aggregation in living organisms very often takes place on surfaces like membranes and the impact of a surface on this process depends not only on the surface chemistry but also on its topology. Our goal was to develop a simple lattice model for studying the role of surface roughness in the aggregation kinetics of polypeptide chains and the morphology of aggregates. We showed that, consistent with the experiment, an increase in roughness slows down the fibril formation, and this process becomes inhibited at a very highly level of roughness. We predicted a subtle catalytic effect that a slightly rough surface promotes the self-assembly of polypeptide chains but does not delay it. This effect occurs when the interaction between the surface and polypeptide chains is moderate and can be explained by taking into account the competition between energy and entropy factors.

scholarly journals Particle size effect in the mechanically assisted synthesis of ß-cyclodextrin mesitylene sulfonate

2020 ◽  
Author(s):  
Stéphane Menuel ◽  
Sébastien Saitzek ◽  
Eric Monflier ◽  
Frédéric HAPIOT
Keyword(s):  
Solid State ◽  
Reaction Pathway ◽  
Particle Size Effect ◽  
Data Series ◽  
Modified Cyclodextrins ◽  
Diffusion Phenomena ◽  
The Impact ◽  
Kinetics Of ◽  
Over Time

Mechanically assisted synthesis of organic compounds has recently focused considerable attention as it may be unique in features to selectively orient the reaction pathway. In the continuation of our work on the synthesis of modified cyclodextrins (CDs) via mechanochemical activation, we sought to discriminate the contribution of supramolecular effects and grinding during the course of a reaction in the solid state. As such, we recently investigated the influence of the particles size of β-CD in the synthesis of β-CD mesitylene sulfonate (β-CDMts) in the solid state using a vibrating ball-mill. We were particularly interested in the role of the particles size on the kinetics of the reaction. In this study, we show that grinding β-CD reduces the particles size over time down to a limit of 167 nm. The granulometric composition remains rather invariant for grinding times over 1 h. Each type of β-CD particles reacted with mesitylene sulfonic chloride (MtsCl) to produce β-CDMts. Contrary to what could be intuitively anticipated, smaller particles did not lead to the highest conversions. The impact of grinding over the conversions was limited. Interestingly, the proportion of β-CDMts mono-substituted on the primary face significantly increased over time when the reaction was carried out in the presence of KOH as a base. The data series were confronted with kinetics models to get clues on the way the reactions proceeded. The diversity of possible models suggests that multiple mechanochemical processes can account for the syntheses of β-CDMts in the solid state. Throughout this study, we found that the reactivity depends more upon diffusion phenomena in the crystalline parts of the material than upon the increase in the surface area of the CD particles resulting from grinding.

When Do Legislators Pass on Pork? The Role of Political Parties in Determining Legislator Effort

2009 ◽  
Vol 103 (01) ◽  
pp. 99-112 ◽  
Author(s):  
PHILIP KEEFER ◽  
STUTI KHEMANI
Keyword(s):  
Political Parties ◽  
Political Institutions ◽  
Public Spending ◽  
Systematic Analysis ◽  
Party Formation ◽  
Unique Type ◽  
Development Fund ◽  
Political Incentives ◽  
The Impact

A central challenge in political economy is to identify the conditions under which legislators seek to “bring home the pork” to constituents. We conduct the first systematic analysis of one determinant of constituency service, voter attachment to political parties, holding constant electoral and political institutions. Our analysis takes advantage of data from a unique type of public spending program that is proliferating across developing countries, the constituency development fund (CDF), which offers more precise measures of legislator effort than are common in the literature. Examining the CDF in India, we find that legislator effort is significantly lower in constituencies that are party strongholds. This result, which is robust to controls for alternate explanations, implies that legislators pass on pork when voters are more attached to political parties. It has implications not only for understanding political incentives and the dynamics of party formation, but also for evaluating the impact of CDFs.

scholarly journals The Dynamic Entropy of Tumor Immune Infiltrates: The Impact of Recirculation, Antigen-Specific Interactions, and Retention on T Cells in Tumors

2021 ◽  
Vol 11 ◽  
Author(s):  
Tiffany C. Blair ◽  
Alejandro F. Alice ◽  
Lauren Zebertavage ◽  
Marka R. Crittenden ◽  
Michael J. Gough
Keyword(s):  
T Cells ◽  
Cancer Cells ◽  
Cancer Therapies ◽  
Tumor Infiltration ◽  
Specific Interactions ◽  
Tumor Environment ◽  
Antigen Presenting ◽  
The Impact ◽  
Kinetics Of

Analysis of tumor infiltration using conventional methods reveals a snapshot view of lymphocyte interactions with the tumor environment. However, lymphocytes have the unique capacity for continued recirculation, exploring varied tissues for the presence of cognate antigens according to inflammatory triggers and chemokine gradients. We discuss the role of the inflammatory and cellular makeup of the tumor environment, as well as antigen expressed by cancer cells or cross-presented by stromal antigen presenting cells, on recirculation kinetics of T cells. We aim to discuss how current cancer therapies may manipulate lymphocyte recirculation versus retention to impact lymphocyte exclusion in the tumor.

scholarly journals Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

2020 ◽  
Vol 16 ◽  
pp. 2598-2606
Author(s):  
Stéphane Menuel ◽  
Sébastien Saitzek ◽  
Eric Monflier ◽  
Frédéric Hapiot
Keyword(s):  
Particle Size ◽  
Solid State ◽  
Reaction Pathway ◽  
Particle Size Effect ◽  
Data Series ◽  
Diffusion Phenomena ◽  
The Impact ◽  
Kinetics Of ◽  
Over Time

The mechanically assisted synthesis of organic compounds has recently focused considerable attention as it may be unique in features to selectively direct the reaction pathway. In the continuation of our work on the synthesis of modified cyclodextrins (CDs) via mechanochemical activation, we sought to discriminate the contribution of supramolecular effects and grinding during the course of a reaction in the solid state. As such, we recently investigated the influence of the particle size of β-CD in the synthesis of β-CD mesitylene sulfonate (β-CDMts) in the solid state using a vibrating ball-mill. We were particularly interested in the role of the particle size on the kinetics of the reaction. In this study, we show that grinding β-CD reduces the particles size over time down to a limit of 167 nm. The granulometric composition remains rather invariant for grinding times over 1 h. Each type of β-CD particles reacted with mesitylenesulfonyl chloride (MtsCl) to produce β-CDMts. Contrary to what could be intuitively anticipated, smaller particles did not lead to the highest conversions. The impact of grinding on the conversion was limited. Interestingly, the proportion of β-CDMts mono-substituted on the primary face significantly increased over time when the reaction was carried out in the presence of KOH as a base. The data series were confronted with kinetics models to get insight in the way the reactions proceeded. The diversity of possible models suggests that multiple mechanochemical processes can account for the formation of β-CDMts in the solid state. Throughout the study, we found that the reactivity depended more upon diffusion phenomena in the crystalline parts of the material than on the increase in the surface area of the CD particles resulting from grinding.

Systematic Analysis of Direct Antiglobulin Test Results in Post-artesunate Delayed Hemolysis

2020 ◽  
Author(s):  
Tommaso Ascoli Bartoli ◽  
Luciana Lepore ◽  
Alessandra D'Abramo ◽  
Giovanna Adamo ◽  
Angela Corpolongo ◽  
...  
Keyword(s):  
Univariate Analysis ◽  
Case Series ◽  
Direct Antiglobulin Test ◽  
Systematic Analysis ◽  
Immune Mediated ◽  
Pubmed Database ◽  
Antiglobulin Test ◽  
Erythrocyte Clearance ◽  
Kinetics Of

Abstract Background: “Post-Artesunate Delayed Hemolysis” (PADH) is common after severe malaria episodes. PADH is related to the “pitting” phenomenon and the synchronous delayed clearance of once-infected erythrocytes, initially spared during treatment. However, direct antiglobulin test (DAT) positivity has been reported in several PADH cases, suggesting a contribution of immune-mediated erythrocyte clearance. The aim of the present study was to compare clinical features of cases presenting a positive or negative DAT.Method: Articles reporting clinical data of patients diagnosed with PADH, for whom DAT had been performed, were collected from PubMed database. Data retrieved from single patients were extracted and univariate analysis was performed in order to identify features potentially related to DAT results and steroids use.Results: Twenty-two studies reporting 39 PADH cases were included: median baseline parasitemia was 20.8% (IQR: 11.2-30) and DAT was positive in 17 cases (45.5%). Compared to DAT-negative individuals, DAT-positive patients were older (49.5 vs 31; p=0.01), had a higher baseline parasitemia (27% vs 17%; p=0.03) and were more commonly treated with systemic steroids (11 vs 3 patients, p=0.002). Depth and kinetics of delayed anemia were not associated with DAT positivity.Conclusions: In this case series, almost half of the patients affected by PADH had a positive DAT. An obvious difference between the clinical courses of patients presenting with a positive or negative DAT was lacking. This observation strongly suggests that DAT result is not indicative of a pathogenic role of anti-erythrocytes antibodies in patients affected by PADH, but is rather a marker of immune activation.

scholarly journals Biological hazard risk studies: a comparative analysis of approaches and the role of insurance

2021 ◽  
Vol 37 (2) ◽  
pp. 344-367
Author(s):  
Sergey Belozyorov ◽  
◽  
Olena Sokolovska ◽  
Anna Faizova ◽  
◽  
...  
Keyword(s):  
Global Economy ◽  
Economic Consequences ◽  
Management Tool ◽  
Negative Consequences ◽  
Scientific Publications ◽  
Systematic Analysis ◽  
Theoretical Approaches ◽  
Biological Hazard ◽  
The Impact

The pandemic of the new coronavirus disease (COVID-19) has a huge impact on the global economy, significantly affecting the functioning of all its sectors. In this regard, the search for ways to minimize the negative consequences of such risks is of particular relevance. The article presents the results of a systematic analysis of scientific publications by leading foreign and Russian authors on various aspects of the risks arising from viral threats, as well as ways to reduce the negative consequences of such risks. In particular, studies that evaluate the impact on the economy of various factors that occur during and after epidemics are examined. The analysis of publications showed that researchers distinguish the following factors: 1) the social system of the state; 2) government expenses on the fight against the epidemic; 3) the role of international organizations in combating epidemics in individual countries. Further, various approaches to the construction of models describing the spread of biological threats reflected in publications of representatives of various scientific fields, in particular medical and economicmathematical, including actuarial, modeling are analyzed. Three approaches to modeling the development of infectious diseases are considered, which differ both in the apparatus used and in the predominant field of application of the corresponding models. Particular attention is paid to the contribution that insurance research can make to the development of new theoretical approaches to mitigate the negative economic consequences of COVID-19. The authors distinguish three areas: 1) the use of actuarial models for the analysis and assessment of the risks of biological threats; 2) the use of relevant insurance products in the insurance market as an epidemic risk management tool that provides financial protection; 3) the use of innovative technologies in rendering insurance services (InsurTech).

Investigation of Agglomerated and Porous Ceramic Powders Suitable for Cold Spray

2021 ◽  
Author(s):  
Geoffrey Celeste ◽  
Vincent Guipont ◽  
Djamel Missoum-Benziane
Keyword(s):  
Cold Spray ◽  
Porous Ceramic ◽  
Ceramic Materials ◽  
Deposition Process ◽  
Impact Behavior ◽  
Ceramic Powders ◽  
Crystallite Sizes ◽  
Cold Gas Spraying ◽  
The Impact

Abstract Cold gas spraying is a solid-state deposition process developed for metallic powders as feedstock materials. For ceramic materials; such low temperature-high velocity kinetic process is still questionable but could have interesting advantages. In the CERASOL project (ANR-19-CE08-0009); the nature and the architecture of porous ceramic powders involving agglomerated sub-micrometric grains are investigated. To that purpose; three oxide ceramics powders (alumina; zirconia and yttria) have been prepared for cold spray. These powders were analyzed in order to assess their architecture (composition; particle size; porosity; density; crystallite sizes…). Preliminary cold spray experiments were carried out implementing velocities measurements for various stand-off distances and spraying of coupons with line experiments. The characteristics of the deposited layers have been examined by SEM and XRD in order to discuss the role of the powder architecture on the impact behavior of the nanostructured agglomerated particles. The role of the gas stream that affects the kinetic and the trajectory of the particles are also discussed.

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