Uncovering the Potential of M1-Site-Activated NASICON Cathodes for Zn-Ion Batteries

There is a long-standing consciousness that the rhombohedral NASICON-type compounds as promising cathodes for Li⁺/Na⁺ batteries should have inactive M1(6b) sites with ion (de)intercalation occurring only in the M2 (18e) sites. Of particular significance is that M1 sites active for charge/discharge are commonly considered undesirable because the ion diffusion tends to be disrupted by the irregular occupation of channels, which accelerates the deterioration of battery. However, it is found that the structural stability can be substantially improved by the mixed occupation of Na⁺/Zn²⁺ at both M1 and M2 when using NaV₂(PO₄)₃ (NVP) as a cathode for Zn-ion batteries. The results of atomic-scale scanning transmission electron microscopy, analysis of ab initio molecular dynamics simulations, and an accurate bond-valence-based structural model reveal that the improvement is due to the facile migration of Zn²⁺ in NVP, which is enabled by a concerted Na⁺/Zn²⁺ transfer mechanism. In addition, significant improvement of the electronic conductivity and mechanical properties is achieved in Zn²⁺-intercalated ZnNaV₂(PO₄)₃ in comparison with those of Na₃V₂(PO₄)₃. This work not only provides in-depth insight into Zn²⁺ intercalation and dynamics in NVP unlocked by activating the M1 sites, but also opens a new route toward design of improved NASICON cathodes.     

Non-homogeneous extracellular resistivity affects the current-source density profiles of up-down state oscillations

Rhythmic local field potential (LFP) oscillations observed during deep sleep are the result of synchronized electrical activities of large neuronal ensembles, which consist of alternating periods of activity and silence, termed 'up' and 'down' states, respectively. Current-source density (CSD) analysis indicates that the up states of these slow oscillations are associated with current sources in superficial cortical layers and sinks in deep layers, while the down states display the opposite pattern of source-sink distribution. We show here that a network model of up and down states displays this CSD profile only if a frequency-filtering extracellular medium is assumed. When frequency filtering was modelled as inhomogeneous conductivity, this simple model had considerably more power in slow frequencies, resulting in significant differences in LFP and CSD profiles compared with the constant-resistivity model. These results suggest that the frequency-filtering properties of extracellular media may have important consequences for the interpretation of the results of CSD analysis.     

遥控钥匙门禁系统的路径损耗

在遥控钥匙门禁(RKE)系统中,可以用钥匙扣上的发射器从远端开锁,发射器将无线编码发送到汽车内的接收机。遥控钥匙门禁(RKE)系统通常工作在ISM频段,包括315MHz和433．92MHz。随着远程启动和带校验的RKE的出现,设计     

The incorporation of mono- and bi-functionalized multiwall carbon nanotubes in organic photovoltaic cells

We have successfully prepared mono- and bi-functionalized multiwall carbon nanotubes (MWCNT) with thiophene, amine and thiophene-amine groups. The dispersion of nanotubes has been enhanced and stable optimized dispersions in organic solvents were obtained. These functionalized nanotubes have been successfully incorporated into bulk heterojunction (BHJ) organic photovoltaic (OPV) cells with a poly (3-hexyl thiophene) (P3HT) and [6, 6]-phenyl-C(61)-butyric acid methyl ester (PCBM) photoactive blended layer. The incorporation of MWCNT with different functional groups, in the active layer, results in different cell performance with respect to a reference cell. A maximum power conversion efficiency of 2.5% is achieved with the inclusion of thiophene functionalized nanotubes. This improvement in the device performance is attributed to an extension of the exciton dissociation volume and charge transport properties through the nanotube percolation network in P3HT/CNT, PCBM/CNT or both phases. This is believed to be due to more efficient dispersion of the functionalized nanotubes within the photoactive composite layer.     

Transverse magnetoresistance peculiarities of thermoelectric Lu-doped Bi2Te3 compound due to strong electrical disorder

The n-type thermoelectric Bi_1.9Lu_0.1Te₃ was prepared by microwave-solvothermal method and spark plasma sintering. The magnetic field and temperature dependences of transverse magnetoresistance measured within temperature 2–200 K interval allow finding the peculiarities characteristic for strongly disordered and inhomogeneous semiconductors. The first peculiarity is due to appearance of linear-in-magnetic field contribution to the total magnetoresistance reflected in a crossover from quadratic magnetoresistance at low magnetic fields to linear magnetoresistance at high magnetic fields. The linear magnetoresistance can result from the Hall resistance picked up from macroscopically distorted current paths due to local variations in stoichiometry of the compound studied. The second peculiarity is that both linear magnetoresistance magnitude and crossover field are functions of carrier mobility which is in agreement with the Parish and Littlewood model developed for disordered and inhomogeneous semiconductors. An increase in the mobility due to a decrease in temperature is accompanied by an increase in the magnetoresistance magnitude and a decrease in the crossover field. Finally, the third peculiarity is related to the remarkable deviation of the total magnetoresistance measured at various temperatures from the Kohler's rule. Presence of strong inhomogeneity and disorder in the Bi_1.9Lu_0.1Te₃ structure concluded from the magnetoresistance peculiarities can be responsible for the remarkable reduction in the total thermal conductivity of this compound.     

NiZnCu Ferrite Thick Film with Nano Scale Crystallites Formed by the Aerosol Deposition Method

This paper describes the magnetic properties of NiZnCu ferrite film deposited at room temperature by an aerosol deposition method (ADM). The thickness of the film was 6 μm and the deposition rate was estimated as 2 μm/min. The microstructure of as-deposited at room temperature films consists of randomly oriented nanocrystallites with a size of 20 nm. As-deposited and annealed films exhibited the following magnetic properties: intensity of magnetization M _s= 0.147 T (117 emu/cm³), coercivity H _c= 40.58 kA/m (510 Oe); and M _s= 0.3 T (250 emu/cm³), H _c= 14.95 kA/m (188 Oe), respectively.