Hydrogen storage properties of nanoconfined LiBH4-NaBH4

In this study a eutectic melting composite of 0.62LiBH4-0.38NaBH4 has been infiltrated in two nanoporous resorcinol formaldehyde carbon aerogel scaffolds with similar pore sizes (37 and 38 nm) but different BET surface areas (690 and 2358 m2/g) and pore volumes (1.03 and 2.64 mL/g). This investigation clearly shows decreased temperature of hydrogen desorption, and improved cycling stability during hydrogen release and uptake of bulk 0.62LiBH4-0.38NaBH4 when nanoconfined into carbon nanopores. The hydrogen desorption temperature of bulk 0.62LiBH4-0.38NaBH4 is reduced by ~107 °C with the presence of carbon, although a minor kinetic variation is observed between the two carbon scaffolds. This corresponds to apparent activation energies, EA, of 139 kJ mol-1 (bulk) and 116-118 kJ mol-1 (with carbon aerogel). Bulk 0.62LiBH4-0.38NaBH4 has poor reversibility during continuous hydrogen release and uptake cycling, maintaining 22% H2 capacity after four hydrogen desorptions (1.6 wt.% H2). In contrast, nanoconfinement into the high surface area carbon aerogel scaffold significantly stabilizes the hydrogen storage capacity, maintaining ~70% of the initial capacity after four cycles (4.3 wt.% H2)

Hydrogen Desorption Properties of Bulk and Nanoconfined LiBH4-NaAlH4

Nanoconfinement of 2LiBH4-NaAlH4 into a mesoporous carbon aerogel scaffold with a pore size, BET surface area and total pore volume of Dmax = 30 nm, SBET = 689 m2/g and Vtot = 1.21 mL/g, respectively is investigated. Nanoconfinement of 2LiBH4-NaAlH4 facilitates a reduction in the temperature of the hydrogen release by 132 °C, compared to that of bulk 2LiBH4-NaAlH4 and the onset of hydrogen release is below 100 °C. The reversible hydrogen storage capacity is also significantly improved for the nanoconfined sample, maintaining 83% of the initial hydrogen content after three cycles compared to 47% for that of the bulk sample. During nanoconfinement, LiBH4 and NaAlH4 reacts to form LiAlH4 and NaBH4 and the final dehydrogenation products, obtained at 481 °C are LiH, LiAl, AlB2 and Al. After rehydrogenation of the nanoconfined sample at T = 400 °C and p(H2) = 126 bar, amorphous NaBH4 is recovered along with unreacted LiH, AlB2 and Al and suggests that NaBH4 is the main compound that can reversibly release and uptake hydrogen

Comparison of Falls and its Determinants in the Elderly with and without Knee Osteoarthritis

Background and Objective: The growth of aging reveals the importance of paying attention to the health needs of the elderly. According to some studies, falls and its consequences are more common in the individuals with knee osteoarthritis (KOA) than those without KOA, but due to lack of evidence, its related factors are still unknown. Thus, the aim of this study was to compare the falls and its determinants in the elderly with and without KOA. Methods: In this case-control study, 700 older adults in two groups of elderly with and without KOA were compared in terms of falls and some variables including KOA, sex, age, body mass index, living status, quadriceps femoris muscle strength, hand muscles strength, balance, number of comorbidities, number of drugs used, walking duration, physical activity and frailty. KOA was diagnosed based on The American College of Rheumatology (ACR) criteria. Findings: In this study, falls were 1.90 times higher in the elderly with KOA than elderly without KOA. Although all variables were significantly different in case and control groups, only female gender (p=0.035) and KOA (p=0.012) were significantly associated with falls. Conclusion: These findings suggest that variables in combination may increase the risk of falls in the elderly with KOA, while each of them alone may not be associated with falls

Evaluation of Seismic Behavior of a Braced Tubular Steel Structure by Pseudodynamic Testing

The inelastic seismic behavior of an X-braced, tubular Introduction To exploit limited oil resources, many offshore drilling towers are constructed in seismically active areas, such as the coastal regions of Southern California. To reduce construction costs while maintaining conservative safety precautions, the American Petroleum Institute (API) design criteria [1] permit inelastic deformations of structural members during severe earthquake excitations. However, the API provisions specify that the structures should remain stable and develop high energy-absorption capabilities under extreme seismic conditions. Experimental studies regarding the inelastic behavior of such structures provide valuable information for assessing design criteria and for improving current analytical techniques. Recently, an on-line computercontrol (pseudodynamic) method has been developed to simulate quasi-statically the inelastic dynamic response of structures to seismic excitations. The pseudodynamic method retains the economy and versatility of conventional quasi-static testing. Moreover, it produces results as informative as those of shaking table tests by accounting for the changing dynamic characteristics of a test structure. This experimental technique was initiated at the University of Tokyo in Japan, where it was successfully applied to the testing of building systems and component

A historical overview of the classification, evolution, and dispersion of Leishmania parasites and sandflies

Background The aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale. Methodology and Principal Findings Leishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate? Conclusions and Significance We propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites

Methods for accurate high-temperature Sieverts-type hydrogen measurements of metal hydrides

The potential of high-temperature metal hydrides (HTMHs) as thermal energy storage materials means that accurate assessment of their properties is required on the laboratory scale. Above ≃ 450 °C, the hydrogen permeability through sample cell reactors (SCRs) used in experiments to characterise HTMHs can have an appreciable impact on the data. In this work, the thermodynamic and kinetic properties of TiHx have been measured at temperatures up to 725 °C as a test of different practical methods for limiting the effects of hydrogen permeability and solubility in SCRs during high-temperature characterisation of metal hydrides. Aluminium-coated stainless steel and α-SiC were used to construct SCRs with reduced hydrogen permeability using commercially available techniques. When steel SCRs are the only practical option, guidelines have been developed to choose experimental conditions that minimise the effect on the data collected due to their hydrogen permeability and solubility. A method has also been developed to correct collected data for the hydrogen permeability and solubility of SCRs