First Report of Lasiodiplodia hormozganensis Causing Leaf Spot Disease on Areca catechu in China.

The areca palm (Areca catechu L.) is one of the significant cash crops in Hainan Province (China), and a valuable tropical medicinal plant (Cao et al. 2020). In September 2020, spots were found on about 80% of the area of the leaves in a 1,000-acre plantation of areca palms in Haikou City, Hainan Province, and the average incidence was 25%. Initially, Elliptical or irregular dark brown spots appeared on the leaves, with an average size of about 1.5 cm2. With the further expansion of the disease, the spot turned light brown in the center with dark brown edges and a prominent yellow halo. Later stage of the disease, the spots became grayish-white in the center, with obvious whorls, on which many small black spots (pycnidia) were scattered. Eventually the leaves dried out. Ten leaves with typical symptoms were collected from the field. Lesion marginal tissues (5×5 mm2) were surfaced sterilized in 75% ethanol for 20 s, followed by 4 min in 1% NaClO, rinsed 3 times with sterile water, plated on PDA and incubated at 28 ℃. A fungus was isolated with a 98% isolation rate. This strain was named HNAC-5. Subcultures were 80 mm in diameter, white, villous, and neatly edged, after two days of incubation at 28 ℃ in dark. Pycnidia were solitary or clustered in stromata, with orifices that oozed black liquid. Conidiogenous cells were colorless and short cylindrical. Conidia unicellular, initially hyaline, aseptate, ellipsoid to ovoid with granular content, becoming pigmented, 1-septate with longitudinal striations, and measuring 20-31×10-13 µm (n=100). These morphological characteristics were similar to Lasiodiplodia spp. (Abdollahzadeh et al. 2010). The internal transcribed spacer region of rDNA, ß-tubulin gene, and translation elongation gene were amplified using ITS1/ITS4, Bt2a/Bt2b, and EF1-728F/EF1-986R primers, respectively (Alves et al. 2008; Glass and Donaldson 1995; White et al. 1990). The resulting sequences were deposited in GenBank under accession numbers OR272043, OR282568, and OR282567. BLAST analysis showed that the three sequences of HNAC-5 were more than 99% similar to strain CBS 124709 of L. hormozganensis. Phylogenetic analysis was performed using the maximum likelihood method based on the three-gene combined dataset with MEGA 7.0 software. The results indicated that HNAC-5 was grouped in the same clade as other L. hormozganensis Abdollahzadeh, Zare & A.J.L. Phillips. Pathogenicity test was carried out on 15 healthy leaves by in vivo inoculation. Ten leaves were pricked with a sterile needle and divided into group 1 and 2. The remaining five uninjured leaves were group 3. Group 1 and 3 were inoculated with 5-mm-diameter mycelial plugs obtained from 3-day cultures, and group 2 treated with PDA plugs served as controls. Fifteen leaves were cultured at 28°C and 100% relative humidity. After 5 days, leaves of group 1 showed symptoms of the disease and on the tenth day showed the same symptoms as the initial onset of the disease in the field, while leaves of Group 2 and 3 showed no symptoms. Pathogenicity tests were conducted three times with the same results. L. hormozganensis was re-isolated from the inoculated symptomatic leaves, thus, Koch's postulates were confirmed. In China, L. hormozganensis has been reported to cause Bougainvillea spectabilis Willd. branch blight disease (Li et al. 2015), and Scaevola taccada (Gaertn.) Roxb. leaf spot disease (Zhang et al. 2020). To our knowledge, this is the first report of L. hormozganensis causing leaf spot disease on A. catechu in China.

LAB-to-FAB Transition of 2D FETs: Available Strategies and Future Trends.

The last decade has seen dramatic progress in research on FETs with 2D channels. Starting from the single devices fabricated using exfoliated flakes in the early 2010s, by the early 2020s, 2D FETs being trialed for mass production and vertical stacking of 2D channels made by leading semiconductor companies. However, the industry is focused solely on transition metal dichalcogenide (TMD) channels coupled with conventional 3D oxide insulators such as Al2O3 and HfO2. This has resulted in numerous challenges, such as poor-quality interfaces and reliability limitations due to oxide traps. At the same time, the alternative routes for 2D FETs offered by laboratory (LAB) research have not been appreciated until now, even though the use of the native oxides of 2D channels has recently resulted in the first 2D FinFETs. Considering the research progress achieved in the last decade, from this perspective, we will discuss the main challenges for industry integration of 2D FETs and also suggest possible future steps which could propel these emerging technologies towards market applications.

Tuning Optimum Temperature Range of Bi2 Te3 -Based Thermoelectric Materials by Defect Engineering.

Bi2 Te3 -based solid solutions, which have been widely used as thermoelectric (TE) materials for the room temperature TE refrigeration, are also the potential candidates for the power generators with medium and low-temperature heat sources. Therefore, depending on the applications, Bi2 Te3 -based materials are expected to exhibit excellent TE properties in different temperature ranges. Manipulating the point defects in Bi2 Te3 -based materials is an effective and important method to realize this purpose. In this review, we focus on how to optimize the TE properties of Bi2 Te3 -based TE materials in different temperature ranges by defect engineering. Our calculation results of two-band model revel that tuning the carrier concentration and band gap, which is easily realized by defects engineering, can obtain better TE properties at different temperatures. Then, the typical paradigms about optimizing the TE properties at different temperatures for n-type and p-type Bi2 Te3 -based ZM ingots and polycrystals are discussed in the perspective of defects engineering. This review can provide the guidance to improve the TE properties of Bi2 Te3 -based materials at different temperatures by defects engineering.

Liquid-Phase Hot Deformation to Enhance Thermoelectric Performance of n-type Bismuth-Telluride-Based Solid Solutions.

Bismuth-telluride-based solid solutions are the best commercial thermoelectric materials near room temperature. For their n-type polycrystalline compounds, the maximum figures of merit (zTs) are often less than 1.0 due to the degraded carrier mobility resulting from the loss of texture. Herein, a liquid-phase hot deformation procedure, during which the Bi2(Te,Se)3 ingots are directly hot deformed with the extrusion of liquid eutectic phase, is performed to enhance the thermoelectric performance of n-type Bi2(Te,Se)3 alloys. The deformation-induced dynamic recrystallization is remarkably suppressed due to the reduction of nucleation sites and the release of deformation stress by liquid phase, contributing to a weakened carrier scattering and enhanced carrier mobility. The liquid eutectic phase also facilitates the rotation of grains and enhanced (000l) texture, further improving carrier mobility. In addition, the dense dislocations and lattice distortion introduced into the matrix reduce the lattice thermal conductivity. As a result, a high zT value of 1.1 at 400 K is obtained, about 75% increment over the normal one-step hot deformed alloys. This work not only demonstrates a simple and efficient technique for achieving superior n-type Bi2Te3-based materials, but also elucidates the important role of liquid eutectic phase in hot deformation.

Evolution of the Intrinsic Point Defects in Bismuth Telluride-Based Thermoelectric Materials.

In polycrystalline bismuth telluride-based thermoelectric materials, mechanical-deformation-induced donor-like effects can introduce a high concentration of electrons to change the thermoelectric properties through the evolution of intrinsic point defects. However, the evolution law of these point defects during sample preparation remains elusive. Herein, we systematically investigate the evolution of intrinsic point defects in n-type Bi2Te3-based materials from the perspective of thermodynamics and kinetics, in combination with positron annihilation measurement. It is found that not only the mechanical deformation but also the sintering temperature is vital to the donor-like effect. The mechanical deformation can promote the formation of cation vacancies and facilitate the donor-like effect, and the sintering process can provide excess energy for Bi antisite atoms to surmount the diffusion potential barrier. This work provides us a better understanding of the evolution law of intrinsic point defects in Bi2Te3-based alloys and guides us to control the carrier concentration by manipulating intrinsic point defects.