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With the increasing demand for high-specific-strength materials for high-temperature applications, particularly in the aerospace field, novel (TiVCrZr)100−xWx (x = 5, 10, 15 and 20) refractory high-entropy alloys (RHEAs) were developed. The phase formation, microstructure, and mechanical properties were studied. The (TiVCrZr)100−xWx RHEAs exhibit a relatively high specific strength and low density compared with the W-containing RHEAs and most of the W-free RHEAs. In (TiVCrZr)100−xWx RHEAs, Laves, BCC and Ti-rich phases are formed, where the Laves phase is the major phase, and the volume fraction of the BCC phase increases with increasing W content. (TiVCrZr)100−xWx RHEAs exhibit dendrite structures, where W is enriched in the dendrite region, and increasing W-rich precipitations corresponding to the BCC phase are observed. The improvement of the strength and hardness of RHEAs is mainly attributed to the evolution of the microstructure and corresponding strengthening effect of W. The empirical parameters and calculated phase diagram were investigated, which further explain and verify the formation and variation of phases. The present findings give more insights into the formation of multi phases in (TiVCrZr)100−xWx RHEAs, and explore their application potential in the aerospace industry and nuclear reactors due to their high specific strength and low-activation constituent elements. [ABSTRACT FROM AUTHOR]

According to the Kamlet-Abraham-Taft (KAT) polarity parameters (α, β, π*), polymers and solvents can be categorized as hydrogen-bond (H-bond) acidic (α>β) or H-bond basic (α<β). Recently, we proposed a quantitative hydrogen bonding (QHB) analysis to predict the solubility of polymers in ionic liquids (ILs) using the product of ΔαΔβ<0 as an indicator, where Δα is the difference between the H-bond acidic parameters of the polymer and IL, and Δβ is the difference in their basicity, while the prerequisite of the "complementary" principle (i.e., that one component is H-bond acidic and the other is basic) is satisfied. Here, the applicability of QHB analysis was first confirmed by testing the solubilities of carefully chosen polymer/deep eutectic solvent (DES) pairs, as the DESs were eutectic mixtures dominated by hydrogen bonding interactions. Then, our attention focused on the solubility of cellulose in DESs. Our testing results as well as the typical published results were summarized, which indicate that the potential DESs for cellulose dissolution and regeneration must be of the H-bond basic type because the "complementary" principle should be satisfied as a prerequisite. However, the H-bond basic DESs investigated in this study do not show the superior solubility of cellulose that has been commonly observed for H-bond basic ILs, even if the criterion of ΔαΔβ<0 is satisfied for both DESs and ILs. Possible reasons for this discrepancy are given to understand the varying effectiveness in cellulose dissolution for H-bond basic DESs and ILs. [ABSTRACT FROM AUTHOR]

As a potential candidate for the next generation of high-temperature alloys, refractory high entropy alloys (RHEAs) have excellent mechanical properties and thermal stability, especially for high-temperature applications, where the processing of RHEAs plays a critical role in engineering applications. In this work, the wire electrical discharge machining (WEDM) performance of WNbMoTaZrx (x = 0.5, 1) RHEAs was investigated, as compared with tungsten, cemented carbide and industrial pure Zr. The cutting efficiency (CE) of the five materials was significantly dependent on the melting points, while the surface roughness (Ra) was not. For the RHEAs, the CE was significantly affected by the pulse-on time (ON), pulse-off time (OFF) and peak current (IP), while the surface roughness was mainly dependent on the ON and IP. The statistical analyses have shown that the CE data of RHEAs have relatively-smaller Weibull moduli than those for the Ra data, which suggests that the CE of RHEAs can be tuned by optimizing the processing parameters. However, it is challenging to tune the surface roughness of RHEAs by tailoring the processing parameters. Differing from the comparative materials, the WEDMed surfaces of the RHEAs showed dense spherical re-solidified particles at upper recast layers, resulting in larger Ra values. The proportion of the upper recast layers can be estimated by the specific discharge energy (SDE). Following the WEDM, the RHEAs maintained the main BCC1 phase, enriched with the W and Ta elements, while the second BCC2 phase in the Zr1.0 RHEA disappeared. Strategies for achieving a better WEDMed surface quality of RHEAs were also proposed and discussed. [ABSTRACT FROM AUTHOR]

We propose and analyze a temporal concatenation heuristic for solving large-scale finite-horizon Markov decision processes (MDP), which divides the MDP into smaller sub-problems along the time horizon and generates an overall solution by simply concatenating the optimal solutions from these sub-problems. As a "black box" architecture, temporal concatenation works with a wide range of existing MDP algorithms. Our main results characterize the regret of temporal concatenation compared to the optimal solution. We provide upper bounds for general MDP instances, as well as a family of MDP instances in which the upper bounds are shown to be tight. Together, our results demonstrate temporal concatenation's potential of substantial speed-up at the expense of some performance degradation. [ABSTRACT FROM AUTHOR]

• Murayaquinones B-E (1 – 4) were isolated from an insect derived actinobacterium. • Structures of new compounds were elucidated by analysis their spectroscopic data. • Murayaquinone D exhibited cytotoxic activities against six cancer cell lines. Chemical study of the insect-derived bacterium, Streptomyces sp. NA4286, led to the discovery of four new polyketides, murayaquinones B-E (1 – 4), together with a known compound, murayaquinone (5). The structures of new compounds (1 – 4) were determined by extensive analysis of their NMR and HRESIMS data. The absolute configuration of (+)- 1 and (−)- 1 was assigned through comparison of experimental and calculated ECD spectra. Murayaquinone D (3) exhibited potent cytotoxic activities against six human cancer cell lines with IC 50 values ranging from 1.03 to 9.99 μM. [ABSTRACT FROM AUTHOR]

Introduction: Sepsis is characterized by an endotoxin tolerance phenotype that occurs in the stage of infection. Persistent bacterial infection can lead to immune cell exhaustion. Triad3A, an E3 ubiquitin ligase, negatively regulates its activation by TLR4. However, the effect of Triad3A on endotoxin tolerance and bactericidal ability in the state of endotoxin tolerance remains unclear. Methods: Using single dose LPS and repeated LPS stimulated macrophage cell lines at indicated times, we investigated miR‐191, Tirad3A, TRAF3, TLR4, p‐P65, TNF‐α, IL‐1β, and iNOS expression, the effect of miR‐191 on Triad3A and TRAF3, gene loss‐of‐function analyses, the effect of Triad3A on TLR4, p‐P65, cytokine, and mycobactericidal activity in endotoxin tolerant cells infected with Mycobacterium marinum. Results: Here we found that Triad3A is involved in regulating endotoxin tolerance. Our result also displayed that miR‐191 expression is downregulated in macrophages in the state of endotoxin tolerance. miR‐191 can directly bind to Triad3A and TRAF3. Additionally, knockdown of Triad3A can reverse the effect of decreasing TNF‐α and IL‐1β in endotoxin tolerant macrophages. Furthermore, we demonstrated that the TLR4‐NF‐κB‐NO pathway was associated with Triad3A and responsible for the killing of intracellular mycobacteria in a tuberculosis sepsis model. Conclusions: These results provide new insight into the mechanisms of Triad3A induced tolerogenic phenotype in macrophages, which can help the better comprehension of the pathogenesis involved in septic shock with infection of Mycobacterium tuberculosis, and suggest that Triad3A may be a potential drug target for the treatment of severe septic tuberculosis. [ABSTRACT FROM AUTHOR]

Abstract: The Mg–3mol%LaNi3 composition was successfully prepared by different techniques, namely, the composite was synthesized by hydrogen combustion synthesis (HCS) with and without an external high magnetic field. The hydrogen storage capacities and hydriding/dehydriding (H/D) rates of the two composites at different temperatures were evaluated and their structures and morphologies were examined. Our main goal in this study is how to control the process of HCS by the external high magnetic field and to investigate its effect on the hydrogenation properties of the composite and analyze these changes from the relationship between the microstructure and crystalline state and the energy injected into the composite from the external high magnetic field. [Copyright &y& Elsevier]

We retrospectively investigated 326 samples that were collected from goose farms in Hainan Province, China, in 2017. A total of 33 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates were identified from 326 samples, and the 33 CRKP isolates were characterized based on whole-genome sequencing (WGS) data from the Illumina and Oxford Nanopore Technologies (ONT) platforms. All of these 33 CRKP isolates possessed blaNDM-5, and a single isolate coharbored mcr-1 and blaNDM-5, while 4 isolates carried multiple virulence and metal tolerance gene clusters. One CRKP strain (CMG-35-2) was selected for long sequence reading. A hybrid plasmid carrying the virulence, resistance, and metal resistance gene in the strain was found. It possessed 2 backbones [IncFIB(K)-IncFII(K)] within a single plasmid that were closely related to K. pneumoniae plasmids from a human-associated habitat in the United States and from a human isolate in Hong Kong. A mouse abdominal infection model indicated that that strain was of the moderate virulence phenotype. This study revealed that K. pneumoniae on goose farms is an important reservoir for blaNDM-5 and these bacteria are represented by a diversity of sequence types. The heterozygous multiple drug resistance genes carried on plasmids highlighted the genetic complexity of CRKP and the urgent need for continued active surveillance. [ABSTRACT FROM AUTHOR]

• Three new diterpenoids were isolated from an endophytic fungus Phomopsis sp. S12. • The absolute configuration of 1 was assigned by single-crystal X-ray diffractions. • Compound 3 exhibited anti-inflammatory activity. Three new pimarane-type diterpenoids, along with two known compounds, were isolated from an endophytic fungus Phomopsis sp. S12. Their structures were determined by comprehensive analyses of HRESIMS, NMR, CD, as well as single-crystal X-ray diffractions. Compound 3 exhibited anti-inflammatory activity against the production of IL-1β and IL-6 induced by lipopolysaccharide (LPS) in macrophages. A putative biosynthetic pathway for compounds 1 – 5 were also proposed. [ABSTRACT FROM AUTHOR]

Various investigations have expanded the views that tuberculosis is an important risk factor for lung cancer occurrence. Lung cancer originates from chronic inflammation and infection. It is becoming clearer that Mycobacterium tuberculosis (M.tb) in tuberculosis patients meticulously schemes multiple mechanisms to induce tumor formation and is indispensable to participate in the occurrence of lung cancer. In addition, some additional factors such as age, sex and smoking, accelerate the development of lung cancer after Mycobacterium tuberculosis infection. The clarification of these insights is fostering new diagnoses and therapeutic approaches to prevention of the patients developing from tuberculosis into lung cancer. [ABSTRACT FROM AUTHOR]

Plant proteins are gaining popularity as a safe and sustainable source of protein for the world's population because of their lower carbon footprint. Pseudocereals (buckwheat, quinoa, and amaranth) are sources of proteins with an ideal composition of amino acids (AAs) and have become standard foods because of their health benefits. Multifunctional peptides prepared from the proteins of pseudocereals are used to treat various chronic diseases. Thus, it is essential to understand the biological functions of these peptides. This review summarizes the producing, separating, and identifying methods as well as biological properties of pseudocereal protein-derived bioactive peptides with identified sequences. A comparative analysis of the quality of pseudocereal proteins and peptides and their biological functions is presented. The current limitation and future possibilities of pseudocereal cultivation and challenges and opportunities of pseudocereal peptides were discussed. Various protein fractions from pseudocereals are enzymatically hydrolysed to produce a dynamic range of biologically active peptides. The critical factors in the production of these novel peptides are the enzyme type, the reaction conditions, and the type of treatment. Amaranth peptides have been shown to have antihypertensive, antioxidant, and anti-inflammatory properties, and buckwheat and quinoa hydrolysates have excellent antimicrobial, anticancer, and antidiabetic activities. The 11S globulin protein fractions show potent activity to inhibit angiotensin-converting enzyme and dipeptidyl peptidase IV. It was observed that the short sequence AAs have been shown to possess good antihypertensive activity. We conclude that pseudocereals are an alternative source of complete protein that can be used to make peptides with demonstrated efficacy in the treatment of chronic diseases. • Pseudocereals are considered functional grains worldwide. • Pseudocereal peptides are antioxidant, antidiabetic, antithrombotic and antihypertensive. • Fewer in vivo tests are performed to validate these activities. • Future challenges and opportunities of pseudocereals peptides are proposed. [ABSTRACT FROM AUTHOR]

Multicopy utility-based forwarding algorithms are popular in opportunistic mobile networks. They aim to gain high system throughput while keeping the cost low. However, most of them ignore the fairness issue on the successful delivery rate among users. In this paper, we analyze the fairness evaluation of the success rate distribution, and we propose a new fair packet-forwarding strategy based on packet priority. We formulate the opportunistic packet-forwarding process as a discrete-time Markov chain and deduce a stationary probability distribution vector. Instead of taking the hill-climbing heuristic on utility comparison, we introduce a lower utility tolerance mechanism for the decision-making process of each node, and we theoretically demonstrate that the proposed mechanism may be used to control the success rate of packet delivery by changing a simple parameter. In addition, we adopt a message-duplication restricting mechanism to adjust the number of replications based on packet priority. Our proposed protocol can work as a plug-in for traditional utility-based forwarding algorithms. The performance is compared with several well-known opportunistic routing protocols via both a synthetic model and real human mobility traces. The results show that our protocol improves the fairness in successful delivery rates among users while maintaining almost the same system throughput. Moreover, it reduces the cost of traditional utility-based forwarding algorithms, rendering our proposed scheme not only fair but efficient as well. [ABSTRACT FROM PUBLISHER]

The article reports that there was no detectable surge in the transmission of COVID-19 that could be attributed to the Wisconsin Primary Election held on April 7, 2020. It states a deconvolution-based method was used to reconstruct the COVID-10 pandemic curve using dates of infection and estimated the instantaneous reproduction number from March 25 to April 18. It mentions while 71 people who either worked at the polls or voted in person tested positive for COVID-19 but had nonvoting exposures.

Abstract: The aim of this paper is to apply a new kinetic model in order to investigate kinetic mechanism of the hydriding kinetics at 553K and hydrogen pressure range from 0.256 to 0.992MPa in the two-phase (α–β) region of the Mg–8mol%LaNi0.5 composition prepared by different methods. Much attention was put on the influence of the fabrication technique and the initial hydrogen pressure on hydriding kinetics of Mg–8mol%LaNi0.5 composite. This model has been validated by comparison of our calculation results with experimental data. The hydriding kinetic mechanism of Mg–8mol%LaNi0.5 was determined and the rate-limited step in the two-phase (α–β) region is hydrogen diffusion in the β phase. [Copyright &y& Elsevier]

Abstract: The structural and kinetic characteristics of the mechanically alloyed Mg1.9Al0.1Ni were investigated. It was found that Mg1.9Al0.1Ni can absorb/desorb about 3.55/3.44 mass% H at a high rate and it has a hexagonal crystal structure as Mg2Ni. The hydriding/dehydriding (H/D) rates in the two-phase (α–β) region of Mg1.9Al0.1Ni were measured and studied at temperatures ranging from 553 to 623K under an approximately isobaric condition. The obtained data of H/D rates indicated that hydrogen diffusion was the rate-controlling step through the hydride phase. A new model was successfully used to calculate the kinetic experimental results. It can be seen that theoretical calculation agrees well with experimental data. The corresponding activation energies are 47 600 and 54 500J/mol H2 for H/D processes, respectively. [Copyright &y& Elsevier]

Abstract: The La0.5Ni1.5Mg17 alloy prepared by hydriding combustion synthesis (HCS) was investigated by an isovolumetric method and X-ray diffraction and this alloy has a large hydrogen storage capacity with good hydriding/dehydriding (H/D) kinetics. The kinetics of hydrogen absorption/desorption (A/D) in the two-phase (–) region has been studied between 523 and 573K under approximately isobaric conditions and the experimental data were analyzed to find the kinetics mechanisms for both the H/D processes. It is shown that the rate-controlling step of the H/D processes is the diffusion of hydrogen, due to the good agreement between the experimental results and calculated curves using a simple new kinetic model. The activation energies are calculated to be 86.8kJ/mol H2 for absorption and 84.9kJ/mol H2 for desorption, which were much smaller than that of MgH2, and can be attributed to the La and Ni additions. [Copyright &y& Elsevier]

Abstract: The in situ composite Cu–Cr alloy, a new type of potential electric material that can be used for contact cables, is reported in this paper. The combination property and thermal stability of the in situ composite Cu–Cr alloy were investigated. Experimental results showed that the in situ composite Cu–Cr alloy has not only high room temperature properties, including ultimate tensile strength σ b, elongation rate 5, relative conductivity σ r, and combination property that is scaled by M index (), but also excellent thermal stability of these properties. At room temperature, the combination property of in situ composite Cu–Cr could be up to 18.3 × 106 MPa2%, which is higher than those of commonly used copper contact cables all over the world. After being heated for 3h at 500°C, the combination property of the in situ composite Cu–Cr alloy only decreased 3%. In this paper, the relationship between thermal stability and strengthening mechanism of in situ composite alloy was analyzed. [Copyright &y& Elsevier]

Abstract: The hydriding/dehydriding (H/D) rates in the two-phase (α–β) region of LaNiMg17 were determined and investigated at temperature ranges from 523 to 623K under approximately isobaric condition. The obtained data of H/D rates indicated that the rate-controlling step was the hydrogen diffusion through the hydride phase. The new model developed by us has been used to these experiments, from which two formulae describing the H/D processes are obtained in an explicit analytic form. The corresponding activation energy is 71000J/mole H2 for both processes. It can be seen that the theoretical calculation consists with the experimental data very well. [Copyright &y& Elsevier]

The radical S-adenosylmethionine (SAM) superfamily enzymes reductively cleave SAM to produce a highly reactive 5ˊ-deoxyadenosyl (dAdo) radical, which in most cases abstracts a hydrogen from the substrate and initiates highly diverse reactions. In rare cases, the dAdo radical can add to a sp 2 carbon to result in the production an adenosylated product. These radical SAM-dependent adenosylation reactions are present in natural product biosynthetic pathways and can be achieved by using unnatural substrate analogs containing olefin or aryl moieties. This Opinion provides a focused perspective on this emerging type of biochemistry and discusses its potential use in bioengineering and biocatalysis. [ABSTRACT FROM AUTHOR]

A procedure for the Raman spectra calculation of vitreous and molten silicates was presented in this paper. It includes molecular dynamics MD simulation for the generation of equilibrium configurations, Wilson’s GF matrix method for the calculations of eigenfrequencies and corresponding vectors, electro-optical parameters method (EOPM) for the Raman intensity calculations, and the bond polarizability model (BPM) for the determination of polarizability and polarizability derivative. One of the most important characteristics of this procedure is the achievement of the partial Raman spectra of five tetrahedral units, as well as the total spectral envelope. In this paper, the calculation was carried out for the vitreous and molten calcium silicates with different compositions and at various temperatures. It is worthwhile to note that the calculation is based on statistical configurations distribution in the space and so it is not needed to artificially adjust the full width at half maximum (FWHM) of spectra. It was also tested through the good agreement of the calculated spectra with the experimental, including some regularity of spectral properties. According to the calculation, the symmetrical stretching of whole tetrahedral units, to which the stretching of Si-Onb bond gives the main contribution to intensity, is proven to be the dominance in the high-frequency range (800–1200 cm-1) and the symmetrical bending of Si-Ob-Si, to which the stretching of Si-Ob bond exhibits the main contribution, is the dominance in the medium-frequency range (400–700 cm-1). As the first theoretical results, the Raman scattering coefficient of each Qi was found little change along with the variation of composition and temperature. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: Two homologous meroterpenoid gene clusters consisting of contiguous genes encoding polyketide synthase (PKS), prenyltransferase (PT), terpenoid cyclase (TC) and other tailoring enzymes were identified from two phylogenetically distinct fungi through computational analysis. Media optimization guided by reverse‐transcription PCR (RT‐PCR) enabled two strains to produce eight new and two known meroterpenoids (1–10). Using gene inactivation, heterologous expression, and biochemical analyses, we revealed a new polyketide‐terpenoid assembly line that utilizes a pair of PKSs to synthesize 2,4‐dihydroxy‐6‐alkylbenzoic acid, followed by oxidative decarboxylation, farnesyl transfer, and terpene cyclization to construct the meroterpenoid scaffold. In addition, two of the isolated meroterpenoids (3 and 17 d) showed immunosuppressive bioactivity. Our work reveals a new strategy for meroterpenoid natural products discovery, and reveals the biosynthetic pathway for compounds 1–10. [ABSTRACT FROM AUTHOR]

Abstract: Two homologous meroterpenoid gene clusters consisting of contiguous genes encoding polyketide synthase (PKS), prenyltransferase (PT), terpenoid cyclase (TC) and other tailoring enzymes were identified from two phylogenetically distinct fungi through computational analysis. Media optimization guided by reverse‐transcription PCR (RT‐PCR) enabled two strains to produce eight new and two known meroterpenoids (1–10). Using gene inactivation, heterologous expression, and biochemical analyses, we revealed a new polyketide‐terpenoid assembly line that utilizes a pair of PKSs to synthesize 2,4‐dihydroxy‐6‐alkylbenzoic acid, followed by oxidative decarboxylation, farnesyl transfer, and terpene cyclization to construct the meroterpenoid scaffold. In addition, two of the isolated meroterpenoids (3 and 17 d) showed immunosuppressive bioactivity. Our work reveals a new strategy for meroterpenoid natural products discovery, and reveals the biosynthetic pathway for compounds 1–10. [ABSTRACT FROM AUTHOR]

We consider the social welfare model of Naor [20] and revenue-maximization model of Chen and Frank [7], where a single class of delay-sensitive customers seek service from a server with an observable queue, under state dependent pricing. It is known that in this setting both revenue and social welfare can be maximized by a threshold policy, whereby customers are barred from entry once the queue length reaches a certain threshold. However, no explicit expression for this threshold has been found. This paper presents the first derivation of the optimal threshold in closed form, and a surprisingly simple formula for the (maximum) revenue under this optimal threshold. Utilizing properties of the Lambert W function, we also provide explicit scaling results of the optimal threshold as the customer valuation grows. Finally, we present a generalization of our results, allowing for settings with multiple servers. [ABSTRACT FROM PUBLISHER]

Abstract: A new model has been successfully used to investigate the hydrogen absorption kinetics mechanism of La2Mg17-based composites. The results indicate that different preparation conditions lead to different rate-controlling steps during hydrogen absorption process. For La2Mg17–LaNi5 composite synthesized by the method of melting, the rate-controlling step is the surface penetration of hydrogen atoms, which does not change by addition agent (LaNi5). However, mechanical milling can change the rate-limiting steps of hydriding reaction in the La2Mg17–LaNi5 composite from surface penetration to diffusion of hydrogen in the hydride layer. With the enhancement of milling intensity, the rate-controlling step in La1.8Ca0.2Mg14Ni3 alloy changes from surface penetration to diffusion. In addition, the activation energies of hydrogen absorption for La2Mg17−20wt%LaNi5 and La1.8Ca0.2Mg14Ni3 are obtained by this model. [Copyright &y& Elsevier]

Abstract: The Mg2FeH6 hydrogen storage metal hydride was successfully prepared by controlled hydriding combustion synthesis (CHCS) in a single process from Mg and Fe elemental powders in a hydrogen atmosphere. Several factors including the magnetic intensity, the compression pressure and the mixing technique have an influence on the microstructure, phase composition and transformation morphology, which contributes strongly to the observed experimental results which show an improvement in the dehydrogenation properties. As a result, the 2Mg+Fe composite can desorb as much as 6.75 mass% within 1000s due to the above synergy effect, especially the effect of a high magnetic field. [Copyright &y& Elsevier]

Abstract: Two kinetic models (Jander model and Chou model) are used to investigate the hydrogen absorption kinetic mechanism of Zr-based AB2 type Laves phase alloys (Ti0.1Zr0.9Mn0.9V0.1Fe0.5Co0.5, Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5 and Ti0.1Zr0.9Mn0.9V0.1Fe0.55Ni0.55). The analysis shows that the rate-controlling step is the diffusion process at high temperatures in the range from 673K to 923K with a low hydrogen concentration (solid solution phase). Both models can well describe the experimental data but Chou model is preferred. Chou model is simpler and easier to use for analyzing the experimental results. The activation energies calculated using Chou model with the least square method are 29.3kJ/mol H2 for Ti0.1Zr0.9Mn0.9V0.1Fe0.5Co0.5, 43.8kJ/mol H2 for Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5 and 48.5kJ/mol H2 for Ti0.1Zr0.9Mn0.9V0.1Fe0.55Ni0.55, which are close to the values reported in the literature (28.3kJ/mol H2 for Ti0.1Zr0.9Mn0.9V0.1Fe0.5Co0.5 and 40.3±1.5kJ/mol H2 for both Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5 and Ti0.1Zr0.9Mn0.9V0.1Fe0.55Ni0.55). [Copyright &y& Elsevier]

Abstract: The feasibility of using the controlled hydriding combustion synthesis (CHCS) under a high magnetic field to prepare the Mg–La–Ni ternary hydrogen storage alloys was studied. Comparison was made between the conventional hydriding combustion synthesis (HCS) and the CHCS. The influence of a high magnetic field on the physicochemical properties (thermodynamic and kinetic characteristics, hydrogen absorption/desorption (A/D) properties, thermal behavior, phase composition and morphology) of the Mg–La–Ni composite was analyzed and the results suggested that a high magnetic field can change the microstructure and phase compositions, decrease the hydriding/dehydriding (H/D) temperature and the particle size of the composite, and increase the H/D rates. Based on this study, the lower-temperature metal hydrides prepared by CHCS seem to be technically feasible for lab-scale and it could represent a possible and attractive alternative to prepare the hydrogen storage materials. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to study the effect of the initial hydrogen pressure on hydriding kinetics in the two-phase region (α–β) of the ternary alloy Mg2−x Ag x Ni (x =0.05, 0.1). The experiments were carefully performed by a volumetric technique under initial hydrogen pressures ranging from 0.298 to 1.203MPa at 553K. The experimental investigation suggests that an increase of the initial hydrogen pressure results in an acceleration of hydriding reacted fraction. A new kinetic model developed in our laboratory recently was successfully applied to this system and the rate-controlling step in the hydriding process was hydrogen diffusion in the β phase. Our study further revealed that a higher content of silver in the Mg2−x Ag x Ni alloys leads to a faster rate of hydriding; the hydriding kinetics of Mg2Ni could be improved by a partial substitution of Ag for Mg. [Copyright &y& Elsevier]

Abstract: Two semi-empirical models have been presented by the stepwise regression method and atomic parameters for the formation enthalpy (ΔH) in the hydriding process and the hydrogen storage capacity (C) of Mg2−x A x Ni1−y B y alloy systems. The main factors influencing ΔH and C are given and we illustrate the relationship between the macroscopic characteristics and atomic structure. In general a decrease in ΔX 2 and an increase in (e/a)2/3 as well as T will result in an increase of p eq and ΔH. On the other hand, when ΔX 2 and T increase but (e/a)2/3 and Z/R decrease, C will increase. The calculated results by the models presented in this paper are in good agreement with our experimental data, the calculated ΔH and C values were within 6.5kJmol−1 H and 0.5mass% H. [Copyright &y& Elsevier]

Abstract: The effects of droplet size and cooling rate on the undercooling of droplet solidification were investigated in the present paper, and the relation between the droplet size and cooling rate versus the undercooling was obtained by DSC. It is shown that the undercooling increases with the decrease of droplet size and increase of cooling rate. Moreover, it is interesting to find that the undercooling and its change rate increase significantly with the droplet size below 20 μm on condition that the cooling rate remains unchanged. Additionally, it is a novelty that the change trend of undercooling decreases with the increasing cooling rate. [Copyright &y& Elsevier]

A new model for predicting the reacted fraction of hydriding/dehydriding (H/D) in powder hydrogen storage materials has been developed, which offers an analytic form expressing the reacted fraction of hydrogen absorption/desorption (A/D) as a function of time, temperature and pressure explicitly. Therefore it is simple and practical. Besides, an important new concept, so called the “characteristic absorption/desorption time” has been introduced that greatly simplifies the formulae and offers some significant physical meaning that might be useful for theoretical discussion in future. The application of this new model to Mg1.95Ag0.05Ni and LaNiMg17 alloys indicates that this new model works very well. [Copyright &y& Elsevier]