다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

A review of shape memory alloy research, applications and opportunities

Physical Review B

Hexagonal boron nitride (h-BN) is a layered material with a graphite-like structure in which planar networks of BN hexagons are regularly stacked. As the structural analogue of a carbon nanotube (CNT), a BN nanotube (BNNT) was first predicted in 1994; since then, it has become one of the most intriguing non-carbon nanotubes. Compared with metallic or semiconducting CNTs, a BNNT is an electrical insulator with a band gap of ca. 5 eV, basically independent of tube geometry. In addition, BNNTs possess a high chemical stability, excellent mechanical properties, and high thermal conductivity. The same advantages are likely applicable to a graphene analogue-a monatomic layer of a hexagonal BN. Such unique properties make BN nanotubes and nanosheets a promising nanomaterial in a variety of potential fields such as optoelectronic nanodevices, functional composites, hydrogen accumulators, electrically insulating substrates perfectly matching the CNT, and graphene lattices. This review gives an introduction to the rich BN nanotube/nanosheet field, including the latest achievements in the synthesis, structural analyses, and property evaluations, and presents the purpose and significance of this direction in the light of the general nanotube/nanosheet developments.

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Boron Nitride Nanotubes and Nanosheets

Due to their high energy density and low material cost, lithium–sulfur batteries represent a promising energy storage system for a multitude of emerging applications, ranging from stationary grid storage to mobile electric vehicles. This review aims to summarize major developments in the field of lithium–sulfur batteries, starting from an overview of their electrochemistry, technical challenges and potential solutions, along with some theoretical calculation results to advance our understanding of the material interactions involved. Next, we examine the most extensively-used design strategy: encapsulation of sulfur cathodes in carbon host materials. Other emerging host materials, such as polymeric and inorganic materials, are discussed as well. This is followed by a survey of novel battery configurations, including the use of lithium sulfide cathodes and lithium polysulfide catholytes, as well as recent burgeoning efforts in the modification of separators and protection of lithium metal anodes. Finally, we conclude with an outlook section to offer some insight on the future directions and prospects of lithium–sulfur batteries.

Designing high-energy lithium–sulfur batteries

https://northumbria-test.eprints-hosting.org/id/document/260823

Surface stability of spinel MgNi0.5Mn1.5O4 and MgMn2O4 as cathode materials for magnesium ion batteries

The surface of anatase TiO2 nanocrystals with an average size of ~20 nm was modified by PMMA through γ radiation. The modified nanocrystals were investigated with photoluminescence (PL) and Fourier transform infrared (FTIR) spectra. A stable blue luminescence peak (~420 nm) can be observed for the modified anatase TiO2 nanocrystal.

Photoluminescence from TiO 2 /PMMA Nanocomposite Prepared by γ Radiation

The formation of various intrinsic point defects in Y3Fe5O12 and their effect on the magnetic performance were studied using density functional theory. The formation of vacancies and interstitial defects shows great dependence on the chemical potential, whereas antisite and Frenkel defects show less dependence on the chemical potential. The oxygen vacancy (VO) and Fe vacancy (VFe), and the oxygen interstitial (IO), Fe interstitial (IFe), and antisite defects (FeY, YFeOct, and YFeTetra) show relatively low formation energies, which may be the common intrinsic defects in Y3Fe5O12. The presence of VO and the Frenkel defect of Fe in YIG does not affect the magnetic moment. The presence of VFeOct and YFeOct results in an increase in the magnetic moment, and the presence of VFeTetra and YFeTetra results in a decrease in the magnetic moment. FeY and IFe cause an increase in the magnetic moment.

Intrinsic defects in yttrium iron garnet: A first-principles study

Strain engineering can effectively improve the energy band degeneracy of two-dimensional transition metal dichalcogenides so that they exhibit good thermoelectric properties under strain. In this work, we have studied the phonon, electronic, thermal, and thermoelectric properties of 1T-phase monolayer HfS2 with biaxial strain based on first-principles calculations combined with Boltzmann equations. At 0% strain, the results show that the lattice thermal conductivity of monolayer HfS2 is 5.01 W m-1 K-1 and the electronic thermal conductivities of n-type and p-type doped monolayer HfS2 are 2.94 and 0.39 W m-1 K-1, respectively, when the doping concentration is around 5 × 1012 cm-2. The power factors of the n-type and p-type doped monolayer HfS2 are different, 29.4 and 1.6 mW mK-2, respectively. Finally, the maximum ZT value of the n-type monolayer HfS2 is 1.09, which is higher than 0.09 of the p-type monolayer HfS2. Under biaxial strain, for n-type HfS2, the lattice thermal conductivity, the electronic thermal conductivity, and the power factor are 1.55 W m-1 K-1, 1.44 W m-1 K-1, and 22.9 mW mK-2 at 6% strain, respectively. Based on the above factor, the ZT value reaches its maximum of 2.29 at 6% strain. For p-type HfS2, the lattice thermal conductivity and the electronic thermal conductivity are 1.12 and 1.53 W m-1 K-1 at 7% strain, respectively. Moreover, the power factor is greatly improved to 29.5 mW mK-2. Finally, the maximum ZT value of the p-type monolayer HfS2 is 3.35 at 7% strain. It is obvious that strain can greatly improve the thermoelectric performance of monolayer HfS2, especially for p-type HfS2. We hope that the research results can provide data references for future experimental exploration.

Improved Thermoelectric Performance of Monolayer HfS2 by Strain Engineering.

Self-charging lithium ion batteries (SCLIBs) that hybridize mechanical energy harvesting and storage processes into one process can be fabricated using a piezoelectric polyvinylidene fluoride (PVDF) film as a separator in lithium ion batteries. In this paper, the deintercalation reaction at LiCoO2 and intercalation reaction at graphite were studied under an internal piezoelectric field using density functional theory. It was found that the internal piezoelectric field applied on the anode can increase intercalation energies and diffusion behavior, at the same time, and the internal piezoelectric field facilitates the deintercalation reaction at the cathode. The simulation results revealed the self-charging mechanism of SCLIBs, in which the piezoelectric potential can assist the deintercalation and intercalation proccesses at the cathode and anode upon self-charging, which may be responsible for the experimentally observed efficiency of SCLIBs.

Zhiguo Wang

Papers

Surface stability of spinel MgNi0.5Mn1.5O4 and MgMn2O4 as cathode materials for magnesium ion batteries

Photoluminescence from TiO 2 /PMMA Nanocomposite Prepared by γ Radiation

Intrinsic defects in yttrium iron garnet: A first-principles study

Improved Thermoelectric Performance of Monolayer HfS2 by Strain Engineering.

Modeling and Simulation of Piezoelectrically Driven Self-Charging Lithium Ion Batteries