Uncovering the Effect of Al Addition on the Hydrogen Storage Properties of the Ternary TiVNb Alloy

The effect of Al addition on the structure, microstructure and hydrogen storage properties of the ternary TiVNb alloy was investigated from small amounts to equimolar composition. Al_x(TiVNb)_1−x (x = 0.05, 0.175 and 0.25) alloys are bcc single-phase materials with decreasing lattice parameters with increasing Al content. Al addition progressively decreases the hydrogen storage capacity but also destabilizes fcc dihydride formation for alloys with x ≤ 0.10. Among the different compositions, the most promising alloy was found to be that with x = 0.05 Al content that exhibited high initial storage capacity (2.96 wt.%), a less stable hydride (ΔH = −52 kJ/mol H₂ and ΔS = −141 J/K∙mol H₂), better desorption properties (desorption onset temperature around 100 °C) and enhanced reversible capacity during cycling (2.83 wt.%) compared to the ternary TiVNb. In situ and ex situ synchrotron X-ray powder diffraction, together with thermal desorption experiments, showed improved desorption properties with Al addition, together with a two-step reaction with hydrogen. These findings highlight the use of small quantities of lightweight Al in refractory multi-principal element alloys as a promising approach for enhancing the solid-state hydrogen storage performance of bcc-type alloys.     

Hydrogen Sorption Behavior of Cast Ag-Mg Alloys

In this paper, the hydrogen sorption properties of casted Ag-Mg alloys were investigated. The obtained alloys were structurally analyzed by X-ray diffraction (XRD) and observed by scanning electron microscopy (SEM). The study was carried out for four alloys from the two-phase region (Mg) + γ′ (AgMg₄) with nominal concentrations of 5 wt. %, 10 wt. %, 15 wt. %, and 20 wt. % Ag, four alloys with nominal compositions equivalent to intermetallic phases: AgMg₄, AgMg₃, AgMg, and Ag₃Mg, one alloy from the two-phase region AgMg + Ag₃Mg (Ag60Mg40), and one alloy from the two-phase region AgMg + AgMg₃ (Ag40Mg60). The hydrogenation process was performed using a Sievert-type sorption analyzer. The hydride decomposition temperature and kinetic properties of the synthesized hydrides were investigated by differential scanning calorimetry (DSC) coupled with thermogravimetric analysis (TGA). Samples with high magnesium content were found to readily absorb significant amounts of hydrogen, while hydrogen absorption was not observed for samples with silver concentrations higher than 50 at. % (AgMg intermetallic phase).     

Enhanced Hydrogen Storage Kinetics of Nanocrystalline and Amorphous Mg2Ni-type Alloy by Melt Spinning

Mg₂Ni-type Mg₂Ni_1−xCo_x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technique. The structures of the as-spun alloys were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys was tested by an automatic galvanostatic system. The results show that the as-spun (x = 0.1) alloy exhibits a typical nanocrystalline structure, while the as-spun (x = 0.4) alloy displays a nanocrystalline and amorphous structure, confirming that the substitution of Co for Ni notably intensifies the glass forming ability of the Mg₂Ni-type alloy. The melt spinning treatment notably improves the hydriding and dehydriding kinetics as well as the high rate discharge ability (HRD) of the alloys. With an increase in the spinning rate from 0 (as-cast is defined as spinning rate of 0 m/s) to 30 m/s, the hydrogen absorption saturation ratio (R5a) of the (x = 0.4) alloy increases from 77.1 to 93.5%, the hydrogen desorption ratio (R20d) from 54.5 to 70.2%, the hydrogen diffusion coefficient (D) from 0.75 × 10⁻¹¹ to 3.88 × 10⁻¹¹ cm²/s and the limiting current density I_L from 150.9 to 887.4 mA/g.     

Molecular Beam-Thermal Desorption Spectrometry (MB-TDS) Monitoring of Hydrogen Desorbed from Storage Fuel Cell Anodes

Different types of experimental studies are performed using the hydrogen storage alloy (HSA) MlNi_3.6Co_0.85Al_0.3Mn_0.3 (Ml: La-rich mischmetal), chemically surface treated, as the anode active material for application in a proton exchange membrane fuel cell (PEMFC). The recently developed molecular beam—thermal desorption spectrometry (MB-TDS) technique is here reported for detecting the electrochemical hydrogen uptake and release by the treated HSA. The MB-TDS allows an accurate determination of the hydrogen mass absorbed into the hydrogen storage alloy (HSA), and has significant advantages in comparison with the conventional TDS method. Experimental data has revealed that the membrane electrode assembly (MEA) using such chemically treated alloy presents an enhanced surface capability for hydrogen adsorption.     

Synthesis and Stability of Hydrogen Storage Material Aluminum Hydride

Aluminum hydride (AlH₃) is a binary metal hydride with a mass hydrogen density of more than 10% and bulk hydrogen density of 148 kgH2/m3. Pure aluminum hydride can easily release hydrogen when heated. Due to the high hydrogen density and low decomposition temperature, aluminum hydride has become one of the most promising hydrogen storage media for wide applications, including fuel cell, reducing agents, and rocket fuel additive. Compared with aluminum powder, AlH₃ has a higher energy density, which can significantly reduce the ignition temperature and produce H₂ fuel in the combustion process, thus reducing the relative mass of combustion products. In this paper, the research progress about the structure, synthesis, and stability of aluminum hydride in recent decades is reviewed. We also put forward the challenges for application of AlH₃ and outlook the possible opportunity for AlH₃ in the future.     

Pull-Out Strength and Bond Behavior of Prestressing Strands in Prestressed Self-Consolidating Concrete

With the extensive use of self-consolidating concrete (SCC) worldwide, it is important to ensure that such concrete can secure uniform in-situ mechanical properties that are similar to those obtained with properly consolidated concrete of conventional fluidity. Ensuring proper stability of SCC is essential to enhance the uniformity of in-situ mechanical properties, including bond to embedded reinforcement, which is critical for structural engineers considering the specification of SCC for prestressed applications. In this investigation, Six wall elements measuring 1540 mm × 2150 mm × 200 mm were cast using five SCC mixtures and one reference high-performance concrete (HPC) of normal consistency to evaluate the uniformity of bond strength between prestressing strands and concrete as well as the distribution of compressive strength obtained from cores along wall elements. The evaluated SCC mixtures used for casting wall elements were proportioned to achieve a slump flow consistency of 680 ± 15 mm and minimum caisson filling capacity of 80%, and visual stability index of 0.5 to 1. Given the spreads in viscosity and static stability of the SCC mixtures, the five wall elements exhibited different levels of homogeneity in in-situ compressive strength and pull-out bond strength. Test results also indicate that despite the high fluidity of SCC, stable concrete can lead to more homogenous in-situ properties than HPC of normal consistency subjected to mechanical vibration.     

First Exploratory Study on the Ageing of Rammed Earth Material

Rammed earth (RE) is attracting renewed interest throughout the world thanks to its “green” characteristics in the context of sustainable building. In this study, the ageing effects on RE material are studied on the walls which have been constructed and exposed for 22 years to natural weathering. First, mechanical characteristics of the “old” walls were determined by two approaches: in-situ dynamic measurements on the walls; laboratory tests on specimens which had been cut from the walls. Then, the walls’ soil was recycled and reused for manufacturing of new specimens which represented the initial state. Comparison between the compressive strength, the Young modulus of the walls after 22 years on site and that of the initial state enables to assess the ageing of the studied walls.     

Hydrogen sulfide mediates the vasoactivity of garlic

The consumption of garlic is inversely correlated with the progression of cardiovascular disease, although the responsible mechanisms remain unclear. Here we show that human RBCs convert garlic-derived organic polysulfides into hydrogen sulfide (H(2)S), an endogenous cardioprotective vascular cell signaling molecule. This H(2)S production, measured in real time by a novel polarographic H(2)S sensor, is supported by glucose-maintained cytosolic glutathione levels and is to a large extent reliant on reduced thiols in or on the RBC membrane. H(2)S production from organic polysulfides is facilitated by allyl substituents and by increasing numbers of tethering sulfur atoms. Allyl-substituted polysulfides undergo nucleophilic substitution at the alpha carbon of the allyl substituent, thereby forming a hydropolysulfide (RS(n)H), a key intermediate during the formation of H(2)S. Organic polysulfides (R-S(n)-R'; n > 2) also undergo nucleophilic substitution at a sulfur atom, yielding RS(n)H and H(2)S. Intact aorta rings, under physiologically relevant oxygen levels, also metabolize garlic-derived organic polysulfides to liberate H(2)S. The vasoactivity of garlic compounds is synchronous with H(2)S production, and their potency to mediate relaxation increases with H(2)S yield, strongly supporting our hypothesis that H(2)S mediates the vasoactivity of garlic. Our results also suggest that the capacity to produce H(2)S can be used to standardize garlic dietary supplements.     

Hydrogen Permeation Behavior of Zirconium Nitride Film on Zirconium Hydride

Hydrogen permeation barrier plays an important role in reducing hydrogen loss from zirconium hydride matrix when used as neutron moderator. Here, a composite nitride film was prepared on zirconium hydride by in situ reaction method in nitrogen atmosphere. The phase structure, morphology, element distribution, and valence states of the composite film were investigated by XRD, SEM, AES, and XPS analysis. It was found that the composite nitride film was continuous and dense with about 1.6 μm thickness; the major phase of the film was ZrN, with coexistence of ZrO₂, ZrO, and ZrN_0.36H_0.8; and Zr-C, Zr-O, Zr-N, O-H, and N-H bonds were detected in the film. The existence of ZrN_0.36H_0.8 phase and the bonds of O-H and N-H revealed that the nitrogen and oxygen in the film could capture hydrogen from the zirconium hydride matrix. The hydrogen permeation performance of nitride film was compared with oxide film by permeation reduction factor (PRF), vacuum thermal dehydrogenation (VTD), and hydrogen permeation rate (HPR) methods, and the results showed that the hydrogen permeation barrier effects of nitride film were better than that of oxide film. The zirconium nitride film would be a potential candidate for hydrogen permeation barrier on the surface of zirconium hydride.     

Resistivity Testing of Palladium Dilution Limits in CoPd Alloys for Hydrogen Storage

Palladium satisfies most of the requirements for an effective hydrogen storage material with two major drawbacks: it has a relatively low gravimetric hydrogen density and is prohibitively expensive for large scale applications. Pd-based alloys should be considered as possible alternatives to a pure Pd. The question is how much one can dilute the Pd concentration in a variety of candidate materials while preserving the hydrogen absorption capability. We demonstrate that the resistivity measurements of thin film alloy samples can be used for a qualitative high-throughput screening and study of the hydrogen absorbing properties over the entire range of palladium concentrations. Contrary to palladium-rich alloys where additional hydrogen scattering indicates a degree of hydrogen content, the diluted alloy films respond by a decrease in resistance due to their thickness expansion. Evidence of significant hydrogen absorption was found in thin CoPd films diluted to just 20% of Pd.     

ER membrane-localized oxidoreductase Ero1 is required for disulfide bond formation in the rice endosperm

The developing endosperm of rice (Oryza sativa, Os) synthesizes a large amount of storage proteins on the rough (r)ER. The major storage proteins, glutelins and prolamins, contain either intra or intermolecular disulfide bonds, and oxidative protein folding is necessary for the sorting of the proteins to the protein bodies. Here, we investigated an electron transfer pathway for the formation of protein disulfide bonds in the rER of the rice endosperm, focusing on the roles of the thiol-disulfide oxidoreductase, OsEro1. Confocal microscopic analysis revealed that N-glycosylated OsEro1 is localized to the rER membrane in the subaleurone cells, and that targeting of OsEro1 to the rER membrane depends on the N-terminal region from Met-1 to Ser-55. The RNAi knockdown of OsERO1 inhibited the formation of native disulfide bonds in the glutelin precursors (proglutelins) and promoted aggregation of the proglutelins through nonnative intermolecular disulfide bonds in the rER. Inhibition of the formation of native disulfide bonds was also observed in the seeds of the esp2 mutant, which lacks protein disulfide isomerase-like (PDIL)1;1, but shows enhanced OsEro1 expression. We detected the generation of H₂O₂ in the rER of the WT subaleurone cells, whereas the rER-derived H₂O₂ levels decreased markedly in EM49 homozygous mutant seeds, which have fewer sulfhydryl groups than the WT seeds. Together, we propose that the formation of native disulfide bonds in proglutelins depends on an electron transfer pathway involving OsEro1 and OsPDIL.     

Elastic–Plastic Numerical Analysis of the Spinning Process of SA-372 Steel Used in High-Pressure Hydrogen Storage Cylinders (≥100 MPA)

Elastic–plastic numerical analysis of the spinning process of SA-372 steel is used in high-pressure hydrogen storage to analyze high-pressure hydrogen storage cylinders with high precision and excellent hydrogen embrittlement resistance. The spinning process of SA-372 steel used to form such a cylinder with a pressure of 100 MPa is investigated through elastic–plastic finite element analysis. The variations in the stress, strain, pressure, temperature, and wall thickness during the spinning processes are comprehensively examined, and the optimized processing parameters are determined based on the numerical analysis results. Finally, these optimal parameters are used to conduct actual spin-forming experiments. The numerical results are found to be in excellent agreement with the experimental results, which verifies the feasibility and effectiveness of the proposed elastic–plastic numerical analysis model for the optimization of spinning process parameters. Furthermore, the hydrogen embrittlement test based on ISO 11114-4:2005 method A proves that the cylinder shoulder has a good hydrogen embrittlement resistance.     

Development of Hydrogen Storage Tank Systems Based on Complex Metal Hydrides

This review describes recent research in the development of tank systems based on complex metal hydrides for thermolysis and hydrolysis. Commercial applications using complex metal hydrides are limited, especially for thermolysis-based systems where so far only demonstration projects have been performed. Hydrolysis-based systems find their way in space, naval, military and defense applications due to their compatibility with proton exchange membrane (PEM) fuel cells. Tank design, modeling, and development for thermolysis and hydrolysis systems as well as commercial applications of hydrolysis systems are described in more detail in this review. For thermolysis, mostly sodium aluminum hydride containing tanks were developed, and only a few examples with nitrides, ammonia borane and alane. For hydrolysis, sodium borohydride was the preferred material whereas ammonia borane found less popularity. Recycling of the sodium borohydride spent fuel remains an important part for their commercial viability.     

The Concept about the Regeneration of Spent Borohydrides and Used Catalysts from Green Electricity

Currently, the Brown-Schlesinger process is still regarded as the most common and mature method for the commercial production of sodium borohydride (NaBH₄). However, the metallic sodium, currently produced from the electrolysis of molten NaCl that is mass-produced by evaporation of seawater or brine, is probably the most costly raw material. Recently, several reports have demonstrated the feasibility of utilizing green electricity such as offshore wind power to produce metallic sodium through electrolysis of seawater. Based on this concept, we have made improvements and modified our previously proposed life cycle of sodium borohydride (NaBH₄) and ammonia borane (NH₃BH₃), in order to further reduce costs in the conventional Brown-Schlesinger process. In summary, the revision in the concept combining the regeneration of the spent borohydrides and the used catalysts with the green electricity is reflected in (1) that metallic sodium could be produced from NaCl of high purity obtained from the conversion of the byproduct in the synthesis of NH₃BH₃ to devoid the complicated purification procedures if produced from seawater; and (2) that the recycling and the regeneration processes of the spent NaBH₄ and NH₃BH₃ as well as the used catalysts could be simultaneously carried out and combined with the proposed life cycle of borohydrides.     

Thermodynamic Tuning of Mg-Based Hydrogen Storage Alloys: A Review

Mg-based hydrides are one of the most promising hydrogen storage materials because of their relatively high storage capacity, abundance, and low cost. However, slow kinetics and stable thermodynamics hinder their practical application. In contrast to the substantial progress in the enhancement of the hydrogenation/dehydrogenation kinetics, thermodynamic tuning is still a great challenge for Mg-based alloys. At present, the main strategies to alter the thermodynamics of Mg/MgH₂ are alloying, nanostructuring, and changing the reaction pathway. Using these approaches, thermodynamic tuning has been achieved to some extent, but it is still far from that required for practical application. In this article, we summarize the advantages and disadvantages of these strategies. Based on the current progress, finding reversible systems with high hydrogen capacity and effectively tailored reaction enthalpy offers a promising route for tuning the thermodynamics of Mg-based hydrogen storage alloys.     

A Study of Hydrogen Embrittlement of SA-372 J Class High Pressure Hydrogen Storage Seamless Cylinder (≥100 MPA)

The spinning process will lead to changes in the micro-structure and mechanical properties of the materials in different positions of the high-pressure hydrogen storage cylinder, which will show different hydrogen embrittlement resistance in the high-pressure hydrogen environment. In order to fully study the safety of hydrogen storage in large-volume seamless steel cylinders, this chapter associates the influence of the forming process with the deterioration of a high-pressure hydrogen cylinder (≥100 MPa). The anti-hydrogen embrittlement of SA-372 grade J steel at different locations of the formed cylinders was studied experimentally in three cylinders. The hydrogen embrittlement experiments were carried out according to method A of ISO 11114-4:2005. The relationship between tensile strength, microstructure, and hydrogen embrittlement is analyzed, which provides comprehensive and reliable data for the safety of hydrogen storage and transmission.     

Ovipositional Behavior of Anopheles gambiae Mosquitoes

Mosquito eggs laid within two hours are necessary for transgenic (injection) studies, because mosquito eggs become hard after that period. Thus, in order to have eggs available within this two-hour window, it is important to understand the ovipositional behavior of Anopheles gambiae s.s.. In the present study, the ovipositional behavior of An. gambiae s.s. (Kisumu) was investigated in several different conditions: age of mosquitoes, time post blood meal to access oviposition substrate, and light conditions. Two groups of mosquitoes, 3–5 days old and 9–11 days old were blood-fed. For those mosquito groups, an oviposition dish was set either at 48 hours or 72 hours after the blood meal either in a light condition or in an artificial dark condition. The number of laid eggs was compared among the different conditions. The 3–5 day-old mosquitoes apparently produced a higher number of eggs than 9–11 day-old mosquitoes, while there was no significant difference between the two groups. The number of laid eggs per one surviving blood-fed mosquito in the dark condition was significantly higher than that in the light condition (p = 0.03). Providing an oviposition dish at 72 hours after blood meal resulted in a significantly higher number of laid eggs per one surviving blood-fed mosquito than at 48 hours after blood meal (p = 0.03). In conclusion, the optimal condition to have readily available egg supply for transgenic analysis was as follows: 3–5 day-old mosquitoes with an oviposition dish placed at 72 hours after the blood meal in a dark environment.     

Facilitated Synthesis of Mg2Ni Based Composites with Attractive Hydrogen Sorption Properties

Composites based on Mg₂Ni with 5% activated carbon from apricot stones (ACAP) have been prepared by ball milling and subsequent annealing in hydrogen atmosphere. The purpose of the primary metal (Mg, Ni, and V) milling was to reduce the particle size and achieve a good contact between them, without forming intermetallic compounds. During hydriding/dehydriding at 300 °C the amount of the Mg₂Ni phase progressively increased, and after 10 cycles about 50% Mg₂(Ni,V) was achieved. The hydrogenation produced mainly Mg₂NiH₄, but small amounts of MgH₂ and VH_x were also detected in the powder mixture. Relatively high hydrogen storage capacity and fast hydriding/dehydriding kinetics of the Mg_2.1Ni_0.7V_0.3—5 wt.% ACAP composite were determined both from hydrogen gas phase and electrochemically.     

Protein folding: the stepwise assembly of foldon units

Equilibrium and kinetic hydrogen exchange experiments show that cytochrome c is composed of five foldon units that continually unfold and refold even under native conditions. Folding proceeds by the stepwise assembly of the foldon units rather than one amino acid at a time. The folding pathway is determined by a sequential stabilization process; previously formed foldons guide and stabilize subsequent foldons to progressively build the native protein. Four other proteins have been found to show similar behavior. These results support stepwise protein folding pathways through discrete intermediates.     

Hydroisomerization of n-Butane over Platinum-Promoted Cesium Hydrogen Salt of 12-Tungstophosphoric Acid

The hydroisomerization of n-butane was carried out in a fixed-bed gas-flow reactor over Pt-promoted Cs_2.5H_0.5PW₁₂O₄₀ (denoted as Cs2.5). Two kinds of catalysts, a direct impregnation of Pt on Cs2.5 (denoted as Pt/Cs2.5), as well as a mechanical mixture of Pt/Al₂O₃ and Cs2.5 (denoted as Pt/Al₂O₃+Cs2.5), were used for the hydroisomerization. Pt/Al₂O₃+Cs2.5 showed a higher stationary activity than Pt/Cs2.5 because the Pt particles supported on Al₂O₃ were much smaller than those supported on Cs2.5. The initial activity decreased with increasing H₂ pressure over Pt/Al₂O₃+Cs2.5. This indicates that the hydroisomerization of n-butane over Pt/Al₂O₃+Cs2.5 proceeded through a bifunctional mechanism, in which n-butane was hydrogenated/dehydrogenated on Pt sites and was isomerized on acid sites of Cs2.5. For the hydroisomerization of n-butane over Pt/Al₂O₃+Cs2.5 the hydrogenation/dehydrogenation on Pt sites is a limiting step at a low Pt loading and the isomerization on solid acid sites is a limiting step at a high Pt loading. During the reaction, hydrogen molecules were dissociated to active hydrogen atoms on Pt sites, and then the formed active hydrogen atoms moved to the solid acid sites of Cs2.5 (spillover effect) to eliminate the carbonaceous deposits and suppress the catalyst deactivation. Because Cs2.5 has suitably strong and uniformly-distributed solid acid sites, Pt/Al₂O₃+Cs2.5 showed a higher stationary activity than Pt/Al₂O₃+H-ZSM-5 and Pt/Al₂O₃+SO₄/ZrO₂ for the hydroisomerization of n-butane at a low H₂ pressure.