A new species of Rhopalopsole Klaplek, 1912 with preliminary female identifications in this genus.

Although some females of Plecoptera are described in taxonomic literature, they are difficult to morphologically distinguish among regional congeners, and identifications are often made through inference only. Therefore, females of many species are unknown and it is often difficult to match males and females correctly. Recently, we reviewed the specimens of the genus Rhopalopsole Klaplek, 1912 that we collected and found that differentiation between female subgenital plates is significant and very helpful for the identification of species. A new species of this genus from Sichuan Province, Rhopalopsole singiplatta Yang Du, sp. nov., is established based on morphological and molecular data. In addition, we used modern tree- and genetic distance-based phylogenetic methods to positively associate females with males for six species in total.

Two New Synonyms of Paraleuctra orientalis (Chu, 1928) (Plecoptera: Leuctridae) Based on Morphological and Molecular Data, with Notes on Paraleuctra cervicornis Du and Qian, 2012.

We recently examined specimens of the genus Paraleuctra Hanson, 1941, from Zhejiang Province and Sichuan Province, China, and two new synonyms are established based on morphological and molecular data. Paraleuctra sinica Yang and Yang, 1995, and Paraleuctra tianmushana Li and Yang, 2010, are synonymized with Paraleuctra orientalis (Chu, 1928). Additionally, we provide new images of Paraleuctra cervicornis Du and Qian, 2012, to facilitate identification of this species.

A review of Leuctridae (Insecta, Plecoptera) in Wuyi Mountains, China.

Background: Wuyi Mountains are located in the northern Oriental Region and the edge of the southern Palaearctic Region. They have a unique geographical location, complex landform and superior climatic conditions, providing a good ecological environment for Leuctridae species. However, due to the damage of some holotypes in the 20th century, limited drawings and lack of colour figures, it is necessary to reorganise and supplement the preserved Leuctridae specimens from Wuyi Mountains. New information: In this study, we found that there are twelve species of Leuctridae recorded in Wuyi Mountains, accounting for about 20% of the recorded species of Leuctridae in China. These records include two genera and five new distribution records species: one species of the genus Paraleuctra Hanson, 1941: Paraleuctraorientalis (Chu 1928) and eleven species of the genus Rhopalopsole Klapálek, 1912, including five new distribution records to Wuyi Mountains: Rhopalopsolefengyangshanensis Yang, Shi & Li, 2009; Rhopalopsolesinensis Yang & Yang, 1993; Rhopalopsoleyangdingi Sivec & Harper, 2008; Rhopalopsoleflata Yang & Yang, 1995; Rhopalopsolebasinigra Yang & Yang, 1995. Now a total of twelve species of Leuctridae have been recorded from Wuyi Mountains, Fujian Province of south-eastern China. In this paper, we also provide a key to the male, new images and some notes of these twelve species, except Rhopalopsolerecurvispina (Wu, 1949) and Rhopalopsolespiniplatta (Wu, 1949). We failed to collect these two species and we regard R.recurvispina as a nomen dubium, because there are no distinctive features that can be used to distinguish this species.

The first cavernicolous Leuctridae (Insecta: Plecoptera) nymph from Guizhou, China.

In this study, the first cavernicolous stonefly of China is reported from Guizhou Province, southwestern China. The morphological characteristics show that this species is a member of the genus Rhopalopsole Klaplek, 1912 (Plecoptera: Leuctridae). The pale coloration and the reduced compound eyes indicate that this species could be an obligate troglobitic taxon. The mtDNA COI barcode fragment of this species supports its assignment to Rhopalopsole and suggests it a distant relative to Rhopalopsole longispina Yang Yang, 1991.

The First Study of Mating Mistakes in Stoneflies (Plecoptera) from China, with Remarks on Their Biological Implications.

Currently, information on the biology of Plecoptera from China is scarce, particularly on mating behavior. In this paper, the existence of mating mistakes (erroneous mating attempts) involving 13 Chinese stonefly species (belonging to nine genera and three families) is reported. These erroneous mating behaviors can be included into three different categories: mating attempts between conspecific males (including the formation of erroneous mating balls), mating attempts between different taxa (including displacement attempts during copulation), and mating-related behaviors with non-living objects. From these behaviors, some aspects of stoneflies during mating, such as the physical competition between males, the sensorial mechanisms implied in triggering a mating behavior, the conditions favoring the mating mistakes, and the possible consequences of interspecific mating in the hybrid production, are discussed.

Additions to the fauna and biology of stoneflies (Plecoptera) in Taizi River Basin, Liaoning, with seven new species records to China.

Background: An investigation report of stonefly fauna in Benxi Manchu Autonomous County, Liaoning Province, northeast China (used to be called Manchuria, now includes Liaoning, Jilin, Heilongjiang Provinces and parts of Inner Mongolia, which are adjacent to the Russian Far East and the Korean Peninsula). Materials were studied with field observation in 2018 and 2019. New information: This paper records five families, nine genera and 14 species of stoneflies from Taizi River, Liaoning Province. Nine species have been recorded for the first time in China and the biology of several common species is also reported for the first time.

A new synonym with a new species of Rhopalopsole (Plecoptera: Leuctridae) from China.

Recently, we reviewed the specimens of the genus Rhopalopsole Klaplek, 1912 we have collected and checked the holotype and paratypes of Rhopalopsole duyuzhoui Sivec Harper, 2008. We present morphological evidence that R. duyuzhoui is a junior synonym of Rhopalopsole basinigra Yang Yang, 1995, and that R. basiningra is a new distribution record to Guizhou Province, southwestern China. Additionally, a new species of this genus from Guizhou Province, Rhopalopsole dicondylica Yang Du, sp. nov. is described and illustrated. The new species is compared to the similar species of this genus.

Two new species of Rhopalopsole (Plecoptera: Leuctridae) from Wuyi Mountains of China.

Two new species of Leuctridae (Plecoptera) from Wuyi Mountains, Fujian Province of southeastern China, Rhopalopsole wuyishanensis sp. nov. and Rhopalopsole trichotoma sp. nov. are described and illustrated. The new species are compared to the closely related species of the R. dentata group and the R. shaanxiensis group in this genus, respectively.

Three new synonyms of Rhopalopsole sinensis Yang amp; Yang, 1993 (Plecoptera: Leuctridae).

We recently examined specimens of the Rhopalopsole from Hubei, Ningxia and Shaanxi, China and three new synonyms of Rhopalopsole sinensis Yang Yang, 1993 are established: Rhopalopsole furcata Yang Yang, 1994, Rhopalopsole hongpingana Sivec Harper, 2008 and Rhopalopsole ningxiana Li Yang, 2010 are synonymized with Rhopalopsole sinensis Yang Yang, 1993. We also place Rhopalopsole furcospina (Wu, 1973) as a nomen dubium. Long hairs on the antennae of R. sinensis thought to be diagnostic also occur on Rhopalopsole ampulla Du Qian, 2011, Rhopalopsole exiguspina Du Qian, 2011, and Rhopalopsole memorabilis Qian Du, 2014. We provide new images of several species to facilitate identification.

Polarization-switching pathway determined electrical transport behaviors in rhombohedral BiFeO3 thin films.

We investigated the polarization-switching pathway-dependent electrical transport behaviors in rhombohedral-phase BiFeO3 thin films with point contact geometry. By combining conducting-atomic force microscopy and piezoelectric force microscopy, we simultaneously obtained current-voltage curves and the corresponding domain patterns before and after the polarization switching. The results indicate that for the (001)-oriented film, the abrupt current (due to polarization reversing) increases with the enhanced switching voltage for 109° and 180° switching events. More importantly, the abrupt current can be further improved in (110)- and (111)-oriented thin films, which benefits from the stronger modulation of the interfacial Schottky barrier by the enhanced out-of-plane polarization magnitude. The current on-off ratio obtained in a ∼20 nm thick (111)-oriented BiFeO3 thin film at a readout voltage of ∼3 V exceeds (∼6 × 105)%, which is close to the result from a previous report on ultrathin tetragonal BiFeO3 thin films.

Magnetoelectric phase transition driven by interfacial-engineered Dzyaloshinskii-Moriya interaction.

Strongly correlated oxides with a broken symmetry could exhibit various phase transitions, such as superconductivity, magnetism and ferroelectricity. Construction of superlattices using these materials is effective to design crystal symmetries at atomic scale for emergent orderings and phases. Here, antiferromagnetic Ruddlesden-Popper Sr2IrO4 and perovskite paraelectric (ferroelectric) SrTiO3 (BaTiO3) are selected to epitaxially fabricate superlattices for symmetry engineering. An emergent magnetoelectric phase transition is achieved in Sr2IrO4/SrTiO3 superlattices with artificially designed ferroelectricity, where an observable interfacial Dzyaloshinskii-Moriya interaction driven by non-equivalent interface is considered as the microscopic origin. By further increasing the polarization namely interfacial Dzyaloshinskii-Moriya interaction via replacing SrTiO3 with BaTiO3, the transition temperature can be enhanced from 46 K to 203 K, accompanying a pronounced magnetoelectric coefficient of ~495 mV/cm·Oe. This interfacial engineering of Dzyaloshinskii-Moriya interaction provides a strategy to design quantum phases and orderings in correlated electron systems.

Atomically Resolved Edge States on a Layered Ferroelectric Oxide.

The emerging surface/edge electronic phases driven by broken symmetry effects have attracted great attention in low-dimensional electronic systems. However, experimental proof on their existence in ferroelectric oxides at the atomic scale is still missing. In this work, metallic surface states are observed on layered Bi2WO6 by scanning tunneling microscopy/spectroscopy. Differential conductance is remarkably enhanced near the step edge compared with that on the terrace, forming a one-dimensional edge state. Density functional theory calculations verify that symmetry breaking at the surface determines the electronic structures and O 2p orbitals contribute the most to the density of states around the Fermi level. Our discovery provides a new strategy toward the hidden phases on other correlated oxide surfaces.

Large Switchable Photoconduction within 2D Potential Well of a Layered Ferroelectric Heterostructure.

The coexistence of large conductivity and robust ferroelectricity is promising for high-performance ferroelectric devices based on polarization-controllable highly efficient carrier transport. Distinct from traditional perovskite ferroelectrics, Bi2 WO6 with a layered structure shows a great potential to preserve its ferroelectricity under substantial electron doping. Herein, by artificial design of photosensitive heterostructures with desired band alignment, three orders of magnitude enhancement of the short-circuit photocurrent is achieved in Bi2 WO6 /SrTiO3 at room temperature. The microscopic mechanism of this large photocurrent originates from separated transport of electrons and holes in [WO4 ]-2 and [Bi2 O2 ]+2 layers respectively with a large in-plane conductivity, which is understood by a combination of ab initio calculations and spectroscopic measurements. The layered electronic structure and appropriately designed band alignment in this layered ferroelectric heterostructure provide an opportunity to achieve high-performance and nonvolatile switchable electronic devices.

Controllable Ferroelastic Switching in Epitaxial Self-Assembled Aurivillius Nanobricks.

Layered perovskites with Aurivillius phase have drawn tremendous attention recently, owing to their high ferroelectric Curie temperatures, large spontaneous polarization, and fatigue-free and environment-friendly characteristics. Bi2WO6 is one of the simplest members in the Aurivillius family with superior ferroelastic and photo-electrochemical behaviors. The self-assembly fabrication of its nanoarchitectures and strategic modulation of their ferroelastic switching are crucial toward highly efficient nanoscale applications. In this work, Bi2WO6 nanobrick arrays were epitaxially grown along the orthorhombic direction in a self-assembled way. Such a nanoscale topology supports out-of-plane and in-plane vectors of ferroelectric polarizations, enabling a perpendicular voltage manipulation of these emerging ferroelectric/elastic domains. Combining the scanning probe technique and transmission electron microscopy, we confirmed the in-plane polarization vectors of 78.6 and 101.4° within the crystallographic axes of the nanobricks with respect to the (110) plane of the substrate. Thus, this work provides new opportunities for ferroelectric/elastic engineering in Bi2WO6 nanostructures for a wide range of applications, such as sensing, actuating, and catalysis.