Multimodal X-ray probe station at 9C beamline of Pohang Light Source-II.

In this study, the conceptual design and performance of a multimodal X-ray probe station recently installed at the 9C coherent X-ray scattering beamline of the Pohang Light Source-II are presented. The purpose of this apparatus is to measure coherent X-ray diffraction, X-ray fluorescence and electrical properties simultaneously. A miniature vacuum probe station equipped with a four-point probe was mounted on a six-axis motion hexapod. This can be used to study the structural and chemical evolution of thin films or nanostructures, as well as device performance including electronic transport properties. This probe station also provides the capability of varying sample environments such as gas atmosphere using a mass-flow-control system and sample temperatures up to 600°C using a pyrolytic boron nitride heater. The in situ annealing of ZnO thin films and the performance of ZnO nanostructure-based X-ray photodetectors are discussed. These results demonstrate that a multimodal X-ray probe station can be used for performing in situ and operando experiments to investigate structural phase transitions involving electrical resistivity switching.

Population genetic structure of a recent insect invasion: a gall midge, Asynapta groverae (Diptera: Cecidomyiidae) in South Korea since the first outbreak in 2008.

Outbreaks of Asynapta groverae, an invasive mycophagous gall midge, in South Korea have been repeatedly reported since the first occurrence in 2008. This species is a nuisance to residents owing to its mass emergence from newly built and furnished apartments. Here, the levels of genetic diversity, divergence, and structure of invasive A. groverae populations were investigated to understand their ability to survive in novel locations. Population genetic analyses were performed on seven invasive populations, including the first outbreak, sporadically emerged, and two laboratory-isolated (quarantined) populations, using the mitochondrial COI sequences and the ten novel microsatellite markers developed in this study. Non-indigenous A. groverae managed to maintain their populations for 12 years despite decreased genetic polymorphisms resulting from multiple incidences of founder effects by a small number of colonists. Additionally, the advantageous sustainability of A. groverae in the particle boards from which they emerge suggests that human-mediated dispersal is plausible, which may allow for the successful spread or invasion of A. groverae to new locations. This study is one of the few examples to demonstrate that an insect species successfully invaded new regions despite exhibiting decreased genetic diversity that was maintained for a decade. These findings indicate that the high genetic diversity of the initial founding population and asexual reproduction would contribute to the successful invasion of A. groverae in novel environments.

Nanoscale Soft Wetting Observed in Co/Sapphire during Pulsed Laser Irradiation.

Liquid drops on deformable soft substrates exhibit quite complicated wetting behavior as compared to those on rigid solid substrates. We report on a soft wetting behavior of Co nanoparticles (NPs) on a sapphire substrate during pulsed laser-induced dewetting (PLID). Co NPs produced by PLID wetted the sapphire substrate with a contact angle near 70°, which is in contrast to typical dewetting behavior of metal thin films exhibiting contact angles greater than 90°. In addition, a nanoscale γ-Al2O3 wetting ridge about 15 nm in size and a thin amorphous Al2O3 interlayer were observed around and beneath the Co NP, respectively. The observed soft wetting behavior strongly indicates that the sapphire substrate became soft and deformable during PLID. Moreover, the soft wetting was augmented under PLID in air due to the formation of a CoO shell, resulting in a smaller contact angle near 30°.

Loboplusia coreana sp. nov. from South Korea, only the second species of a genus originally described from Costa Rica (Diptera: Cecidomyiidae, Winnertziinae).

The genus Loboplusia was recently introduced for a remarkable species of Diallactiini from the cloud forest of Costa Rica (Jaschhof 2016). Males of that species, Loboplusia zurqui Jaschhof, 2016, were found to differ fundamentally from other Diallactiini, with the following traits defining the genus. The scutum is provided with a bright membranous patch called the prescutellar window; setae on the legs, especially the tarsi, are fringed; the gonostylus consists of two lobes (not a single lobe as is the basic pattern in Diallactiini); and the bridge connecting the gonocoxites ventrobasally is markedly shortened (Jaschhof 2016: fig. 15). A diallactiine collected recently by one of us (YJB) in South Korea shows exactly the same characters and is no doubt congeneric with L. zurqui. At the same time there are clear distinctions in the genitalia indicating that the South Korean species is discrete, so it is described and named here L. coreana Jaschhof Ham sp. nov. With a single species each in Central America and Eastern Asia, the genus Loboplusia has a distinctly odd distribution, a circumstance that is briefly discussed.