Ionic conductivity and the formation of cubic CaH₂ in the LiBH₄-Ca(BH₄)₂ composite

Abstract LiBH4–Ca(BH4)2 composites were prepared by ball milling. Their crystal structures and phase composition were investigated using synchrotron X-ray diffraction and Rietveld refinement, and their ionic conductivity was measured using impedance spectroscopy. The materials were found to form a physical mixture. The composites were composed of α-Ca(BH4)2, γ-Ca(BH4)2 and orthorhombic LiBH4, and the relative phase quantities of the Ca(BH4)2 polymorphs varied significantly with LiBH4 content. The formation of small amounts of orthorhombic CaH2 and cubic CaH2 in a CaF2-like structure was observed upon heat treatment. Concurrent formation of elemental boron may also occur. The ionic conductivity of the composites was measured using impedance spectroscopy, and was found to be lower than that of ball milled LiBH4. Electronic band structure calculations indicate that cubic CaH2 with hydrogen defects is electronically conducting. Its formation along with the possible precipitation of boron therefore has an effect on the measured conductivity of the LiBH4–Ca(BH4)2 composites and may increase the risk of an internal short-circuit in the cells.</p

Ionic conductivity and the formation of cubic CaH₂ in the LiBH₄-Ca(BH₄)₂ composite

Transient absorption spectroscopy is used to follow the reactive intermediates involved in the first steps in the photochemistry initiated by ultraviolet (266-nm wavelength) excitation of solutions of 1,5-hexadiene, isoprene, and 2,3-dimethylbut-2-ene in carbon tetrachloride or chloroform. Ultraviolet and visible bands centered close to 330 and 500 nm in both solvents are assigned respectively to a charge transfer band of Cl-solvent complexes and the strong absorption band of a higher energy isomeric form of the solvent molecules (iso-CCl3–Cl or iso-CHCl2–Cl). These assignments are supported by calculations of electronic excitation energies. The isomeric forms have significant contributions to their structures from charge-separated resonance forms and offer a reinterpretation of previous assignments of the carriers of the visible bands that were based on pulsed radiolysis experiments. Kinetic analysis demonstrates that the isomeric forms are produced via the Cl–solvent complexes. Addition of the unsaturated hydrocarbons provides a reactive loss channel for the Cl–solvent complexes, and reaction radii and bimolecular rate coefficients are derived from analysis using a Smoluchowski theory model. For reactions of Cl with 1,5-hexadiene, isoprene, and 2,3-dimethylbut-2-ene in CCl4, rate coefficients at 294 K are, respectively, (8.6 ± 0.8) × 109, (9.5 ± 1.6) × 109, and (1.7 ± 0.1) × 1010 M–1 s–1. The larger reaction radius and rate coefficient for 2,3-dimethylbut-2-ene are interpreted as evidence for an H-atom abstraction channel that competes effectively with the channel involving addition of a Cl-atom to a C═C bond. However, the addition mechanism appears to dominate the reactions of 1,5-hexadiene and isoprene. Two-photon excited CCl4 or CHCl3 can also ionize the diene or alkene solute

Aggregating the Bandwidth of Multiple Network Interfaces to Increase the Performance of Networked Applications

Devices capable of connecting to two or more different networks simultaneously, known as host multihoming, are becoming increasingly common. For example, most laptops are equipped with a least a Local Area Network (LAN) and a Wireless LAN (WLAN) interface, and smartphones can connect to both WLANs and 3G-networks (High-Speed Downlink Packet Access, HSDPA). Being connected to multiple networks simultaneously allows for desirable features like bandwidth aggregation and redundancy. Enabling and making efficient use of multiple network interfaces or links (network interface and link will be used interchangeably throughout this thesis) requires solving several challenges related to deployment, link heterogeneity and dynamic behavior. Even though multihoming has existed for a long time, for example routers must support connecting to different networks, most existing operating systems, network protocols and applications do not take host multihoming into consideration. The default behavior is still to use a single interface for all traffic. Using a single interface is, for example, often insufficient to meet the requirements of popular, bandwidth intensive services like video streaming. In this thesis, we have focused on bandwidth aggregation on host multihomed devices. Even though bandwidth aggregation has been a research field for several years, the related works have failed to consider the challenges present in real world networks properly, or does not apply to scenarios where a device is connected to different heterogeneous networks. In order to solve the deployment challenges and enable the use of multiple links in away that works in a real-world network environment, we have created a platform-independent framework, called MULTI. MULTI was used as the foundation for designing transparent (to the applications) and application-specific bandwidth aggregation techniques. MULTI works in the presence of Network Address Translation (NAT), automatically detects and configures the device based on changes in link state, and notifies the application(s) of any changes. The application-specific bandwidth aggregation technique presented in this thesis was optimised for and evaluated with quailty-adaptive video streaming. The technique was evaluated with different types of streaming in both a controlled network environment and real-world networks. Adding a second link gave a significant increase in both video and playback quality. However, the technique is not limited to video streaming and can be used to improve the performance of several, common application types. In many cases, it is not possible to extend applications directly with multilink support. Working on the network-layer allows for the creation of bandwidth aggregation techniques that are transparent to applications. Transparent, network-layer bandwidth aggregation techniques must support the behavior of the different transport protocol in order to achieve efficient bandwidth aggregation. The transparent bandwidth aggregation techniques introduced in this thesis are targeted at Universal Datagram Protocol (UDP) and Transmission Control Protocol (TCP), the two most common transport protocols in the Internet today

Er du i tvil, så er du ikke i tvil.

Tittel: Er du i tvil, så er du ikke i tvil. Hensikt: Sammenligne og vurdere effekten av ulike verktøy for identifisering av omsorgssvikt hos barn på akuttmottak. Problemstilling: Hvordan kan sykepleiere i akuttmottak identifisere barn utsatt for omsorgssvikt? Metode: Oppgaven er en litteraturstudie. Det er gjort søk i CINAHL Complete og PubMed. Resultat: Fysisk undersøkelse, samt følgende kartleggingsverktøy; Hague protocol, SPUTOVAMO og ESCAPE, er effektivt for identifisering av omsorgssvikt. Vi fant også at e-læring og trening er en forutsetning for effektiv bruk av disse verktøyene. Konklusjon: Litteraturstudien vår viser at sykepleiere i akuttmottak kan identifisere barn utsatt for omsorgssvikt ved å benytte seg av godt dokumenterte kartleggingsverktøy, fysisk undersøkelse, i tillegg til opplæring i form av trening og e-læring. Nøkkelord: Child abuse, Neglect, Emergency department, IdentificationTitle: When in doubt, there is no doubt. Objective: To compare and assess different tools for identifying child neglect in emergency departments. Problem: How can a nurse at the emergency department identify children exposed to maltreatment? Method: The searches in this literature study were conducted in CINAHL Complete and PubMed. Results: Physical examination, as well as the following screening tools; The Hague Protocol, SPUTOVAMO and ESCAPE, are effective for identifying child neglect. We also found that e-learning and training are a prerequisite for effective use of these tools. Conclusion: Our literature study shows that nurses at the emergency department can identify children at risk of neglect by using well-documented screening tools, physical examination, in addition to training and e-learning. Keyword: Child abuse, Neglect, Emergency department, Identificatio

Anharmonicity effects and thermal expansion of thermoelectric (M,M’,M”)NiSn (M,M’,M”=Ti, Zr, Hf) half-Heusler alloys

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Anharmonicity effects and thermal expansion of thermoelectric (M,M’,M”)NiSn (M,M’,M”=Ti, Zr, Hf) half-Heusler alloys

This work was funded by the Research Council of Norway within the THELMA project (No. 228854) and Principado de Asturias (IDI/2018/000185 and SV-PA-21-AYUD/2021/51822) projects

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