Solid-State Hydrogen Storage Systems and the Relevance of a Gender Perspective

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 evidence 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 the hydrogen sorption reaction is strongly related to the microstructure and to the morphology (i.e., loose powder or pellets) of the carriers. Usually, the kinetics of the 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, the paper arguments that, as it occurs with the exploitation of other renewable innovative technologies, a wide consideration of the social factors connected to these processes is needed to reach a twofold objective: To assess the extent to which a specific innovation might produce positive or negative impacts in the recipient socioeconomic system and, from a sociotechnical perspective, to explore the potential role of the social components and dynamics in fostering the diffusion of the innovation itself. Within the social domain, attention has been paid to address the underexplored relationship between the gender perspective and the enhancement of hydrogen-related energy storage systems. This relationship is taken into account both in terms of the role of women in triggering the exploitation of hydrogen-based storage playing as experimenter and promoter, and in terms of the intertwined impact of this innovation in their current conditions, at work, and in daily life.

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

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.

Evaluation of physicochemical stability and degradation kinetics of bedaquiline in hydrolytic solutions of different pH

Background Tuberculosis is an infection that has high mortality rate in human as well as in animals if it remains unattained for long time. Scientists are always desirous to discover new molecules against Mycobacterium tuberculosis; one of them is bedaquiline which was recently approved to treat multidrug resistance TB. During the clinical study of new molecule stability and impurity are the key aspects to develop formulation. Stability issues in bulk drug are dangerous to drug safety and needs careful attention in formulation development. Bedaquiline stability study was completed with reversed-phase high-performance liquid chromatography (HPLC) and utilized in degradation kinetic study of bedaquiline in aqueous condition under different pH, temperature, and concentrations of degradant. Results Linearity was obtained in 50.0-250.0μg/ml, correlation coefficient, and regression line equation were 0.998 and Y=18528x + 7E+06 respectively. Intraday, inter day precision, and repeatability RSD were less than 2.0%. Average recovery in accuracy study was more than 98.0% showed that good recovery was obtained. Degradation kinetics parameters like activation energy (Ea), half-life (t50), rate constant (k), and shelf life (t90) were calculated under different condition for bedaquiline. Entropy and enthalpy of reaction was studied to gather knowledge about energy of system. Conclusion The result explained that bedaquiline degradation was pH-dependant, as increase in concentration of degradant and temperature, there was increase in degradation rate of bedaquiline. Bedaquiline was stable in neutral aqueous condition and at lower temperatures, shows that drug is hydrophobic in nature. Kinetic data showed that bedaquiline followed first order kinetics in acidic and alkaline pH.

New thermodynamic activity-based approach allows predicting the feasibility of glycolysis

Thermodynamic feasibility analyses help evaluating the feasibility of metabolic pathways. This is an important information used to develop new biotechnological processes and to understand metabolic processes in cells. However, literature standard data are uncertain for most biochemical reactions yielding wrong statements concerning their feasibility. In this article we present activity-based equilibrium constants for all the ten glycolytic reactions, accompanied by the standard reaction data (standard Gibbs energy of reaction and standard enthalpy of reaction). We further developed a thermodynamic activity-based approach that allows to correctly determine the feasibility of glycolysis under different chosen conditions. The results show for the first time that the feasibility of glycolysis can be explained by thermodynamics only if (1) correct standard data are used and if (2) the conditions in the cell at non-equilibrium states are accounted for in the analyses. The results here will help to determine the feasibility of other metabolisms and to understand metabolic processes in cells in the future.

Thermodynamic Study of Operation Properties Effect on Polymer Electrolyte Membrane Fuel Cells (PEM)

The thermodynamic analysis of PEM fuel cell energy production depends on the entropy and enthalpy of reaction with the changing of the operating temperatures that ranges between 50 and 100ºC, the electrical work done will be equal to the Gibbs free energy released. This paper presents a mathematical model of PEM fuel cells, based on physical-chemical procedures of the phenomena occurring inside the fuel cell, and it was theoretically studied the performance at different operation variables and conditions. The C++ program is designed to calculate all thermo-chemical parameters, i.e. enthalpy of formation, Gibbs free energy, work and efficiency for any type of fuel cells. The results are plotted as a function of fuel cell operating temperature. The results shows that the highest value of Gibbs energy is at the lowest operating temperature, and decreases gradually with increasing the temperature, the output voltage is determined by cell’s reversible voltage that arises from potential difference produced by chemical reaction and several voltage losses that occur inside a cell. In addition the results showed that the efficiency of this type of the fuel cells is much higher than the ideal Carnot’s efficiency, it changes between 82% to 85% depends on temperature operation. The heat output (required heat) from the fuel cell increases with increasing the operating temperature, this heat is used for many thermal applications such as buildings space heating.

Etude de l’influence de la basicité sur l’enthalpie de réaction des sels N-méthoxycarbonyl-(oxy)-pyridiniums

Les hétérocycles sont importants, aussi bien dans les domaines biologique, médicinal et thérapeutique (vitamines, hormones, antibiotiques, etc), que dans le secteur industriel et technologique (inhibiteurs de corrosion, colorants, agents stabilisants, pesticides, herbicides. Les chloroformiates ou chlorocarbonates sont les esters dérivés de l’acide chloroformique. La chimie des N-oxydes hétérocycliques (pyridine et N-oxydes) a connu un important développement au cours des dernières années. L’objectif principal du présent travail est l’étude de l’action du métoxycarbonylchloride sur la pyridine et certains de ses dérivés. Après avoir trouvé les conditions optimales, de nouveaux composés à base de pyridine ont été synthétisés. En remplaçant l’ion chlorure par d’autres ions, les produits synthétisés ont été cristallisés avec un bon rendement. La structure des produits a été caractérisée à l’aide de la spectroscopie infra rouge et la résonnance magnétique nucléaire. Spécifiquement, l’influence de la basicité du noyau hétérocyclique sur les enthalpies de formation des sels produits a été étudiée. En conclusion, la réaction chimique de formation est exothermique avec ΔH° < 0 pour tous les sels étudiés. En utilisant les constantes de Hammett sur le noyau de la pyridine, l’étude a monté que ces chaleurs de réaction dépendent de la basicité du noyau hétérocyclique. En perspective on peut envisager une étude de l’influence de la basicité des différents noyaux pyridiniques sur les effets de conjugaison polaire directe sur le groupe azoté dans les sels N-méthoxycarbonyl-(oxy)-pyridiniums.Mots clés: Pyridine N-Oxyde, chloroformiates, synthèse, constante de Hammett. English Title: Study of the influence of basicity on the enthalpy of reaction of N-methoxycarbonyl- (oxy) -pyridinium salts Heterocycles are important, as well in the biological, medicinal and therapeutic fields (vitamins, hormones, antibiotics, etc.), as in the industrial and technological sector (corrosion inhibitors, dyes, stabilizing agents, pesticides, herbicides). Chloroformates or chlorocarbonates are esters derived from chloroformic acid. The chemistry of heterocyclic N-oxides (pyridine and N-oxides) has experienced significant development in recent years. The main objective of this work is to study the action of metoxycarbonylchloride on pyridine and some of its derivatives. After finding the optimal conditions, new pyridine-based compounds were synthesized. By replacing the chloride ion with other ions, the synthesized products have been crystallized with good yield. Specifically, the influence of the basicity of the heterocyclic nucleus on the enthalpies of salt formation produced has been studied. The enthalpies formation of salt produced have been determined. In conclusion, the chemical reaction of formation is exothermic with ΔH ° < 0 for all the salts studied. Using Hammett's constants on the pyridine nucleus, the study has shown that these reaction heats depend on the basicity of the heterocyclic nucleus. In perspective, we can study the influence of the basicity of the different pyridine rings on the effects of direct polar conjugation on the nitrogen group in the N-methoxycarbonyl- (oxy) -pyridinium salts.Keywords: Pyridine N-Oxide, chloroformates, synthesis, Hammett constant.

Study of Heating and Cooling Rate of Cobalt Oxide-Based TCES System Using Experimental Redox Kinetics Analysis

Cost-effective solar power generation in CSP plants requires the challenging integration of high energy density and high-temperature thermal energy storage with the solar collection equipment and the power plant. Thermochemical energy storage (TCES) is currently a very good option for thermal energy storage, which can meet the industry requirement of large energy density and high storage temperature. TCES specifically exploits reversible chemical reactions wherein heat is absorbed during the forward endothermic reaction and released during the reverse exothermic reaction. The associated enthalpic storage of energy (i.e., the heat of reaction) offers higher density and enhanced stability compared to sensible and latent heat storage. Metal oxide redox reactions are particularly well-suited for TCES given their characteristically high enthalpy of reaction and high reaction temperature. In addition, the air is suitable as both a heat transfer fluid (HTF) and reactant; thus, simplifying process design and eliminating the need for indirect HTF storage and any intermediate heat exchanger. Among the palette of available metal oxides, cobalt oxide is one of the most promising candidates for TCES given its high enthalpy of reaction with high reaction temperature. One of the critical design parameters for TCES reactors is the optimal heating and cooling rates during respective charging and discharging modes of operation. In order to study the effect of heating/cooling rate on cobalt oxide TCES performance, a constant 10°C/min rate was selected for both storage cycle heating and cooling. Considering the intrinsic redox kinetics of cobalt oxide at considered constant heating/cooling rate, we studied milligram scale quantities of cobalt oxide (99.9% purity, 40 μm average particle size) using a dual-mode thermogravimetric (TGA)/differential scanning calorimetry (DSC) system, which simultaneously measures weight change (TGA) and differential heat flow (DSC) as a function of TCES cycling under continuous air purge. In addition, we investigated the cyclic stability of cobalt oxide in the context of the redox kinetics and particle coarsening behavior, employing scanning electron microscopy (SEM). TGA/DSC tests were conducted for 30 successive cycles using pure cobalt oxide. It was shown that pure cobalt oxide in powder form (38μ particle size) could complete both forward and reverse reaction at the selected heating rate with little degradation between cycles. In parallel, SEM was used to examine morphology and particle size changes before and after heating cycles. SEM results proved grain growth occurs even after only five initial cycles.