(Aspleniaceae), a distinct new fern species from northern Guangdong, China, based on morphological data and molecular phylogeny.

A new spleenwort species, , was found and described from Danxia landform region in Guangdong, China. The new species has close resemblance to Ching ex S.H.

Endemic medicinal plant distribution correlated with stable climate, precipitation, and cultural diversity.

Medicinal plants provide crucial ecosystem services, especially in developing countries such as China, which harbors diverse endemic medicinal plant species with substantial cultural and economic value. Accordingly, understanding the patterns and drivers of medicinal plant distribution is critical. However, few studies have investigated the patterns and drivers of endemic medicinal plants distribution in China.

Spatial phylogenetics of the Chinese angiosperm flora provides insights into endemism and conservation.

The flora of China is well known for its high diversity and endemism. Identifying centers of endemism and designating conservation priorities are essential goals for biodiversity studies. However, there is no comprehensive study from a rigorous phylogenetic perspective to understand patterns of diversity and endemism and to guide biodiversity conservation in China.

Reverse transcription recombinase-aided amplification assay for rapid detection of the influenza A(H1N1)pdm09 H275Y mutation that confers oseltamivir resistance.

The emergence of the influenza A(H1N1)pdm09 virus with the NA-H275Y mutation, which confers oseltamivir resistance, must be monitored, especially in patients undergoing neuraminidase inhibitor treatment. In this study, we developed a reverse transcription recombinase-aided amplification assay that has high sensitivity (detection limit: 1.0 × 10 copies/μL) and specificity for detecting the oseltamivir-resistant H275Y mutation; the assay is performed within 30 min at a constant temperature of 39° Celsius using an isothermal device.

Evolutionary history of the angiosperm flora of China.

High species diversity may result from recent rapid speciation in a 'cradle' and/or the gradual accumulation and preservation of species over time in a 'museum'. China harbours nearly 10% of angiosperm species worldwide and has long been considered as both a museum, owing to the presence of many species with hypothesized ancient origins, and a cradle, as many lineages have originated as recent topographic changes and climatic shifts-such as the formation of the Qinghai-Tibetan Plateau and the development of the monsoon-provided new habitats that promoted remarkable radiation. However, no detailed phylogenetic study has addressed when and how the major components of the Chinese angiosperm flora assembled to form the present-day vegetation.

Physical Modeling of Activation Energy in Organic Semiconductor Devices based on Energy and Momentum Conservations.

Field effect mobility in an organic device is determined by the activation energy. A new physical model of the activation energy is proposed by virtue of the energy and momentum conservation equations. The dependencies of the activation energy on the gate voltage and the drain voltage, which were observed in the experiments in the previous independent literature, can be well explained using the proposed model.

A method to measure the distance among scatters and the scatters' diameter in artificial composite materials.

A new method to measure the distance among scatters, the density of scatters, and the scatters' diameter in artificial composite materials has been proposed. This method is based on detecting the reflection amplitude change (amp) of the echo signal reflected from scatters. Simulation results show that such a method is valid for the distance less than four times of the acoustic wavelength, because the coupling between the scatters can be neglected for the distance larger than four times of the acoustic wavelength.

Physical Modeling of Gate-Controlled Schottky Barrier Lowering of Metal-Graphene Contacts in Top-Gated Graphene Field-Effect Transistors.

A new physical model of the gate controlled Schottky barrier height (SBH) lowering in top-gated graphene field-effect transistors (GFETs) under saturation bias condition is proposed based on the energy conservation equation with the balance assumption. The theoretical prediction of the SBH lowering agrees well with the experimental data reported in literatures. The reduction of the SBH increases with the increasing of gate voltage and relative dielectric constant of the gate oxide, while it decreases with the increasing of oxide thickness, channel length and acceptor density.

Effects of Energy Relaxation via Quantum Coupling Among Three-Dimensional Motion on the Tunneling Current of Graphene Field-Effect Transistors.

We report theoretical study of the effects of energy relaxation on the tunneling current through the oxide layer of a two-dimensional graphene field-effect transistor. In the channel, when three-dimensional electron thermal motion is considered in the Schrödinger equation, the gate leakage current at a given oxide field largely increases with the channel electric field, electron mobility, and energy relaxation time of electrons. Such an increase can be especially significant when the channel electric field is larger than 1 kV/cm.

Anisotropic relaxation of a CuO/TiO2 surface under an electric field and its impact on visible light absorption: ab initio calculations.

Ab initio calculations on the anisotropic relaxation of a CuO/TiO2 surface under electric fields and the visible light absorption of these relaxed surfaces are reported. We compare the relaxation of the CuO/TiO2 surface under the electric fields in the direction of [001] or [010]. Fewer Cu-O bonds with highly coordinated Cu-ions are found in the CuO/TiO2 relaxed surface under the electric field in the [010] direction.

The Current Collapse in AlGaN/GaN High-Electron Mobility Transistors Can Originate from the Energy Relaxation of Channel Electrons?

Influence of the energy relaxation of the channel electrons on the performance of AlGaN/GaN high-electron mobility transistors (HEMTs) has been investigated using self-consistent solution to the coupled Schrödinger equation and Poisson equation. The first quantized energy level in the inversion layer rises and the average channel electron density decreases when the channel electric field increases from 20 kV/cm to 120 kV/cm. This research also demonstrates that the energy relaxation of the channel electrons can lead to current collapse and suggests that the energy relaxation should be considered in modeling the performance of AlGaN/GaN HEMTs such as, the gate leakage current, threshold voltage, source-drain current, capacitance-voltage curve, etc.

Interface traps and quantum size effects on the retention time in nanoscale memory devices.

Based on the analysis of Poisson equation, an analytical surface potential model including interface charge density for nanocrystalline (NC) germanium (Ge) memory devices with p-type silicon substrate has been proposed. Thus, the effects of Pb defects at Si(110)/SiO2, Si(111)/SiO2, and Si(100)/SiO2 interfaces on the retention time have been calculated after quantum size effects have been considered. The results show that the interface trap density has a large effect on the electric field across the tunneling oxide layer and leakage current.

Dot size effects of nanocrystalline germanium on charging dynamics of memory devices.

The dot size of nanocrystalline germanium (NC Ge) which impacts on the charging dynamics of memory devices has been theoretically investigated. The calculations demonstrate that the charge stored in the NC Ge layer and the charging current at a given oxide voltage depend on the dot size especially on a few nanometers. They have also been found to obey the tendency of initial increase, then saturation, and lastly, decrease with increasing dot size at any given charging time, which is caused by a compromise between the effects of the lowest conduction states and the capacitance of NC Ge layer on the tunneling.

Finite size effects on the gate leakage current in graphene nanoribbon field-effect transistors.

The finite size effects in nanoribbon graphene field-effect transistors (FETs) make the energy distribution of the channel electrons very different from that when neglecting finite size effects. Such an effect is especially obvious when the width of the graphene ribbon is a few nanometers. Thus, it results in more high-energy electrons in a nanoribbon graphene FET than in a two-dimensional graphene FET for the same device structure and parameters.