The effect of chlorfenapyr exposure on Solenopsis invicta Buren (Hymenoptera: Formicidae)

Liang Yuling,Liang Mingrong,Li Panpan,Song Yunbo,Lu Yongyue 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

Red imported fire ant (RIFA), Solenopsis invicta Buren, pose a serious risk to the agriculture, environment, and public health in areas invaded by this species. Chemical insecticides have been widely used to prevent and control this plaguing pest. To discover a novel and cost-effective compound for controlling fire ants, we examined the toxic effect of chlorfenapyr on fire ants. While chlorfenapyr exhibited an insufficient horizontal toxicity transfer and knockdown effect to fire ants, feeding with chlorfenapyr solution increased fire ant workers’ gathering abilities while decreasing their walking, climbing, and adhesion ability. The mortalities of the small, medium, and large-size workers were 84.17%, 98.75%, and 82.08%, respectively, after 72 h of treatment with 25, 50, and 200 μg/ml chlorfenapyr. Additionally, females and males exhibited more higher tolerance than workers to chlorfenapyr; meanwhile, females showed a higher resistance than males. That is, the mortality of males was 100% after 120 h of treatment with 6.25 μg/ml chlorfenapyr. In contrast, the mortality of females was 79.05% after 144 h of treatment with 100 μg/ml chlorfenapyr. In addition, the chlorfenapyr bait exhibited significant toxicity on fire ants. Treated with 0.01% chlorfenapyr bait showed a better toxic effect than 0.025% during the period of 2 d-7 d. However, the weight of ant corpses was 1.32 and 1.23 g at 12 d of treatment with 0.025% and 0.01% chlorfenapyr bait, respectively. The present research showed that chlorfenapyr appeared to be an effectively potential toxic compound for developing bait to manage S. invicta.

Investigation of microstructures and properties of HVOF sprayed WC-10Co-4Cr coatings on high-hardness M42 steel

Xiaogang Lu,Zhenghua Lin,Peng Pan,Yunbo Chen,Lingli Zuo,Chunming Li 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.6

WC-10Co-4Cr have been well known material with attractive corrosion resistance and excellent hardness in the WC-basedcoatings. To widen the application of the WC-10Co-4Cr coatings deposited on high-hardness metal cutting tools, theinvestigation of its preparation parameters and properties are required. In this study, dense micro-structured WC-10Co-4Crcoatings deposited on high-hardness M42 steel were performed with high velocity oxy-fuel (HVOF) spray process. Theprepared coatings exhibit excellent properties by improving the size of spray gun and injecting high flow nitrogen into theflame stream. A maximum micro-hardness of 1353.3 HV0.3 was achieved. In addition, the frictional properties of uncoated M42steel and the WC-10Co-4Cr coating were comparably studied under dry sliding wear tests. A low friction coefficient of 0.34-0.37 was achieved for WC-10Co-4Cr coating, showing a 57% decrease than that of uncoated M42 steel. X-ray diffractometrywas used to identify the phase composition, and scanning electron microscopy was adopted to characterize the microstructureof deposited coatings and worn-out surfaces.

Efficient Visual Place Recognition by Adaptive CNN Landmark Matching

( Yutian Chen ),( Wenyan Gan ),( Yi Zhu ),( Hui Tian ),( Cong Wang ),( Wenfeng Ma ),( Yunbo Li ),( Dong Wang ),( Jixian He ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.11

Visual place recognition (VPR) is a fundamental yet challenging task of mobile robot navigation and localization. The existing VPR methods are usually based on some pairwise similarity of image descriptors, so they are sensitive to visual appearance change and also computationally expensive. This paper proposes a simple yet effective four-step method that achieves adaptive convolutional neural network (CNN) landmark matching for VPR. First, based on the features extracted from existing CNN models, the regions with higher significance scores are selected as landmarks. Then, according to the coordinate positions of potential landmarks, landmark matching is improved by removing mismatched landmark pairs. Finally, considering the significance scores obtained in the first step, robust image retrieval is performed based on adaptive landmark matching, and it gives more weight to the landmark matching pairs with higher significance scores. To verify the efficiency and robustness of the proposed method, evaluations are conducted on standard benchmark datasets. The experimental results indicate that the proposed method reduces the feature representation space of place images by more than 75% with negligible loss in recognition precision. Also, it achieves a fast matching speed in similarity calculation, satisfying the real-time requirement.

Effects of stocking density on the homeostasis of uric acid and related liver and kidney functions in ducks

Lin Peiyi,Liufu Sui,Wang Jinhui,Hou Zhangpeng,Liang Yu,Wang Haiyue,Li Bingxin,Cao Nan,Liu Wenjun,Huang Yunmao,Tian Yunbo,Xu Danning,Li Xiujin,Fu Xinliang 아세아·태평양축산학회 2024 Animal Bioscience Vol.37 No.5

Objective: Stocking density (SD) is an important issue in the poultry industry, which is related to the production performance, intestinal health and immune status. In the present study, the effects of SD on the metabolism and homeostasis of uric acid as well as the related functions of the liver and kidney in ducks were examined. Methods: A total of 360 healthy 56-day-old Shan-ma ducks were randomly divided into the low stocking density (n = 60, density = 5 birds/m2 ), medium stocking density (n = 120, density = 10 birds/m2 ) and high stocking density groups (HSD; n = 180, density = 15 birds/m2 ). Samples were collected in the 3rd, 6th, and 9th weeks of the experiment for analysis. Results: The serum levels of uric acid, lipopolysaccharide and inflammatory cytokines (interleukin-1β [IL-1β], IL-8, and tumor necrosis factor-α [TNF-α]) were increased significantly in the HSD group. Serious histopathological lesions could be seen in both the livers and kidneys in the HSD group in the 9th week. The mRNA expression levels of inflammatory cytokines (IL-8 and TNF-α) and related pathway components (toll-like receptor 4, myeloid differentiation primary response gene 88, and nuclear factor-κB) were increased significantly in both the livers and kidneys in the HSD group. The mRNA expression levels of enzymes (adenosine deaminase, xanthine oxidase, phosphoribosyl pyrophosphate amidotransferase, and phosphoribosyl pyrophosphate synthetase 1) related to the synthesis of uric acid increased significantly in the livers in the HSD group. However, the mRNA expression level of solute carrier family 2 member 9, which plays an important role in the excretion of uric acid by the kidney, was decreased significantly in the kidneys in the HSD group. Conclusion: These results indicated that a higher SD could cause tissue inflammatory lesions in the liver and kidney and subsequently affect the metabolism and homeostasis of uric acid, and is helpful for guiding decisions related to the breeding and production of ducks.

Controlled crack propagation for atomic precision handling of wafer-scale two-dimensional materials

Shim, Jaewoo,Bae, Sang-Hoon,Kong, Wei,Lee, Doyoon,Qiao, Kuan,Nezich, Daniel,Park, Yong Ju,Zhao, Ruike,Sundaram, Suresh,Li, Xin,Yeon, Hanwool,Choi, Chanyeol,Kum, Hyun,Yue, Ruoyu,Zhou, Guanyu,Ou, Yunbo American Association for the Advancement of Scienc 2018 Science Vol.362 No.6415

<P><B>Cleaving with a metal handle</B></P><P>Using adhesive tape to pull off monolayers of two-dimensional (2D) materials is now a well-established approach. However, the flakes tend to be micrometer scale, and the creation of multilayer stacks for device application can be challenging and time consuming. Shim <I>et al.</I> show that monolayers of a variety of 2D materials, including molybdenum disulfide and hexagonal boron nitride, can be cleaved from multilayers grown as 5-centimeter-diameter wafers. The multilayer is capped with a nickel layer, which can be used to pull off the entire grown stack. The bottom of the stack is again capped with nickel, and a second round of cleaving leaves the monolayer on the bottom nickel layer. The monolayers could be transferred to other surfaces, which allowed the authors to make field-effect transistors with high charge-carrier mobilities.</P><P><I>Science</I>, this issue p. 665</P><P>Although flakes of two-dimensional (2D) heterostructures at the micrometer scale can be formed with adhesive-tape exfoliation methods, isolation of 2D flakes into monolayers is extremely time consuming because it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits high-throughput production of multiple monolayers of wafer-scale (5-centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wafer. Wafer-scale uniformity of hexagonal boron nitride, tungsten disulfide, tungsten diselenide, molybdenum disulfide, and molybdenum diselenide monolayers was verified by photoluminescence response and by substantial retention of electronic conductivity. We fabricated wafer-scale van der Waals heterostructures, including field-effect transistors, with single-atom thickness resolution.</P>