Whether large ferroelectric polarization P exists in the orthorhombic HoMnO 3 with the E-type antiferromagnetic spin ordering or not remains as one of unresolved, challenging issues in the physics of multiferroics. The issue is closely linked to an intriguing experimental difficulty for determining P of polycrystalline specimens that conventional pyroelectric current measurements performed after a poling procedure under high dc electric fields are subject to large errors due to the problems caused by leakage currents or space charges. To overcome the difficulty, we employed the PUND method, which uses successively the two positive and two negative electrical pulses, to directly measure electrical hysteresis loops in several polycrystalline HoMnO 3 specimens below their Néel temperatures. We found that all the * These authors equally contributed to this work. HoMnO 3 samples had similar remnant polarization P r values at each temperature, regardless of their variations in resistivity, dielectric constant, and pyroelectric current levels. Moreover, P r of~0.07 µC/cm 2 at 6 K is consistent with the P value obtained from the pyroelectric current measurement performed after a short pulse poling. Our findings suggest that intrinsic P of polycrystalline HoMnO 3 can be determined through the PUND method and P at 0 K may reach~0.24 µC/cm 2 in a single crystalline specimen.
Doping
with heteroatoms is being used as an effective way to change
electronic structure of electrode materials for advanced storage systems.
Herein, β-MnO2 and rare earth (cerium) doped MnO2 cathode materials have been successfully prepared for aqueous
zinc ion batteries. Cerium doping induced structural transformation
of MnO2 from β- to α-phase, along with the
evident improvement of conductivity, stability, and reversibility.
Compared to the undoped β-MnO2, the doping cathode
possessed excellent cycling stability at a high rate of 5 C and higher
rate capability. Cyclic voltammetry curves, electrochemical impedance
spectroscopy, galvanostatic intermittent titration technique, scanning
electron microscopy, and transmission electron microscopy measurements
demonstrated that cerium doping caused fast Zn2+ diffusion
and excellent electrochemical stability.
This study reports five species of Pareuchiloglanis in the Lancangjiang drainage of China, including descriptions of two new species: P. abbreviatus sp. nov., P. gracilicaudata, P. kamengensis, P. myzostoma and P. prolixdorsalis sp. nov. The two new species are distinguished from P. feae, P. poilanei, P. sichuanensis and P. tianquanensis by a shorter adipose-fin base and the adipose-fin base being separated from the caudal fin, differ from P. sinensis, P. macrotrema, P. longicauda and P. rhabdurus by a more restricted gill opening (not reaching the base of the first pectoral-fin element ventrally), and differ from P. songmaensis by an anal-fin ray count of ii-3-4 (vs. ii-8). Pareuchiloglanis abbreviatus is distinguished from congeners by the tip of the dorsal fin reaching the origin of the adipose fin when depressed. Pareuchiloglanis prolixdorsalis is distinguished from P. gongshanensis, P. macropterus and P. kamengensis by lacking a sulcus between the lower lip and the base of the maxillary barbel, and differs from P. anteanalis by the shorter pectoral fin, the pectoral fin not reaching to the origin of pelvic fin. It differs from P. gracilicaudata, P. myzostoma, P. nebulifer and P. robusta by a caudal-fin ray count of 6+7 (vs. 7+8), and differs from P. abbreviatus by the tip of dorsal fin not reaching to the origin of the adipose fin when depressed (vs. reaching). It differs from P. songdaensis by the distance between the origin of the pelvic fin to the base of the anal fin being longer than that to the mouth (vs. equal).
Purpose: This study reports the clinical and genetic features of Brown-Vialetto-Van Laere syndrome (BVVL) type 2 in a case of uniparental disomy of chromosome 8 in mainland China and analyzes the genotype-phenotype correlation through a review of the literature of BVVL type 2 cases.
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