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Design of Micro Biopsy Device for Wireless Autonomous Endoscope
Wen-Wen Chen,Guo-Zheng Yan,Hua Liu,Ping-Ping Jiang,Zhi-Wu Wang 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
Well-established technology that provides assistance from outside the patient may soon give way to alternative approaches that bythe wireless robotic mechanisms inside the patient through natural orifices. For this study, two kinds of micro biopsy mechanisms weredeveloped for capsule endoscope which could traverse the gut environment automatically. This mobility allows the biopsy device tomove to the area of interest to sample specific tissues. Based on the medical and mechanism considerations, we concerned on designprecise biopsy jaw with sufficient cutting force, and the biopsy process should be safe, repeatable and visible. The lead-screw linkagesystem that actuated jaw of biopsy allowing for large force production. Using one micro-motor, the biopsy process was carried outquickly by three motions: stretching to sampling point; bite and cutting off; withdrawing into capsule body with the sample. With thecontrol and vision system, the biopsy process could compete automatically. The robot was capable of traversing in the gut environmentwirelessly and had been successfully used to biopsy gut tissue in vitro. In addition, experimental analysis of the biopsy mechanismshowed good results towards more elaborate tissue manipulation in the future.
Overexpression of the potato StEPF2 gene confers enhanced drought tolerance in Arabidopsis
Yanli Wang,Tian Xie,Chunli Zhang,Juanjuan Li,Zhi Wang,Hongbing Li,Xiping Liu,Li-Na Yin,Shi-Wen Wang,Sui-Qi Zhang,Xiping Deng,Qingbo Ke 한국식물생명공학회 2020 Plant biotechnology reports Vol.14 No.4
Epidermal patterning factor 2 (EPF2) is a negative regulator of stomatal development, and is essential for plant growth, development, and environmental stress responses. However, the role of EPF2 in potato (Solanum tuberosum) has not been investigated to date. Here, we cloned and characterized the potato EPF2-like gene (StEPF2). StEPF2 is predominantly intercellular space localized and its transcripts were rhythmically expressed, and showed the highest expression in apical unexpanded leaves. Expression of StEPF2 was markedly down-regulated in response to abscisic acid and sodium chloride treatments; however, upon the application of polyethylene glycol, the expression of StEPF2 peaked at 4 h and then decreased gradually. Overexpression of StEPF2 in Arabidopsis (OE) substantially reduced stomatal density and photosynthetic rate, but had little effects on plant growth. Under drought stress, OE lines maintained higher photosynthetic rates, photosystem II efficiency, and instantaneous water use efficiency than wild-type (WT) plants. Moreover, OE lines showed less water loss and hydrogen peroxide accumulation in detached leaves compared with WT plants. Thus, our results suggest that StEPF2 acts as a negative regulator of stomatal development in potato, indicating that the role of EPF2 is conserved across plant species. Overall, StEPF2 represents an important target for the development of drought-tolerant potato cultivars via genetic engineering.
Random vibration analysis of train-slab track-bridge coupling system under earthquakes
Zhi-ping Zeng,Xian-feng He,Yan-gang Zhao,Zhi-wu Yu,Ling-kun Chen,Wen-tao Xu,Ping Lou 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.54 No.5
This study aimed to investigate the random vibration characteristic of train-slab track-bridge interaction system subjected to both track irregularities and earthquakes by use of pseudo-excitation method (PEM). Each vehicle subsystem was modeled by multibody dynamics. A three-dimensional rail-slabgirder-pier finite element model was created to simulate slab track and bridge subsystem. The equations of motion for the entire system were established based on the constraint condition of no jump between wheel and rail. The random load vectors of equations of motion were formulated by transforming track irregularities and seismic accelerations into a series of deterministic pseudo-excitations according to their respective power spectral density (PSD) functions by means of PEM. The time-dependent PSDs of random vibration responses of the system were obtained by step-by-step integration method, and the corresponding extreme values were estimated based on the first-passage failure criterion. As a case study, an ICE3 high-speed train passing a fifteen-span simply supported girder bridge simultaneously excited by track irregularities and earthquakes is presented. The evaluated extreme values and the PSD characteristic of the random vibration responses of bridge and train are analyzed, and the influences of train speed and track irregularities (without earthquakes) on the random vibration characteristic of bridge and train are discussed.
Zhi-ting Zhou,Zhen-nan Fan,Jian-fu Li,Kun Wen,Bide Zhang,Tao Wang,Yan-kun Xia,Zhang Sun,Bing Yao 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6
A field-circuit coupling model of a typical faulty generator is established to correct through-bolt end-region overheating and breakdown failure in a tubular hydro-generator. Using the model, eddy current loss and electromagnetic forces on through bolts under normal and failure conditions are analyzed and compared and the natural frequency of a through bolt is determined. Based on the analysis results, the causative mechanism of failure is revealed and targeted improvement design measures are proposed. The numerical results are found to be consistent with the actual fault characteristics, validating the design measure improvements. The results are useful in improving the design and manufacturing standards and enhancing the operational reliability of large tubular hydrogenerators.
Yan Lv,Xian-Guo Guo,Dao-chao Jin,Wen-Yu Song,Rong Fan,Cheng-Fu Zhao,Zhi-Wei Zhang,Ke-Yu Mao,Yun-Ji Zou,Zhi-Hua Yang 대한기생충학ㆍ열대의학회 2020 The Korean Journal of Parasitology Vol.58 No.2
The chigger mite Leptotrombidium sialkotense is one of the 6 main vectors of scrub typhus in China. Before present study, L. sialkotense was found in some parts of Hunan province, China with a narrow geographical distribution. During field investigation 2016-2017, we found L. sialkotense in Jingha, southern Yunnan, China. Of 15 small mammal host species, L. sialkotense were collected from 6 species of the hosts. Rattus brunneusculus was a dominant host of L. sialkotense, from which 98.3% of the mites were collected. The chigger mite showed a relatively high infestation prevalence (PM=11.7%) and mean abundance (MA=0.5) in comparison with the rest 5 host species. These results reveal a certain host specificity of L. sialkotense to a rat R. brunneusculus. The mite L. sialkotense showed an aggregated distribution on the host (P<0.05). A positive correlation observed between L. sialkotense and the body length of hosts. There was a positive interspecific association between L. sialkotense and 2 other dominant vectors, L. deliense and L. scutellare.
Yan-Ling Chen,Xian-Guo Guo,Wen-Yu Song,Tian-Guang Ren,Lei Zhang,Rong Fan,Cheng-Fu Zhao,Zhi-Wei Zhang,Wenge Dong,Xiao-Bin Huang,Dao-chao Jin 대한기생충학ㆍ열대의학회 2023 The Korean Journal of Parasitology Vol.61 No.3
Chigger mites are the vector of scrub typhus. This study estimates the infestation status and ecological characteristics of chiggers on the chestnut white-bellied rat Niviventer fulvescens in Southwest China between 2001 and 2019. Chiggers were identified under the microscope, and infestation indices were calculated. The Preston’s log-normal model was used to fit the curve of species abundance distribution. A total of 6,557 chiggers were collected in 136 of 342 N. fulvescens rats, showing high overall infestation indices (prevalence=39.8%, mean abundance=19.2, mean intensity=48.2) and high species diversity (S =100, H’=3.0). Leptotrombidium cangjiangense, Neotrombicula japonica, and Ascoschoengastia sifanga were the three dominant chigger species (constituent ratio=42.9%; 2,736/6,384) and exhibited an aggregated distribution among different rat individuals. We identified 100 chigger species, with 3 of them (Leptotrombidium scutellare, Leptotrombidium wenense, and Leptotrombidium deliense) as the main vectors of scrub typhus in China and nine species as potential vectors of this disease. Disease vector occurrence on N. fulvescens may increase the risk of spreading scrub typhus from rats to humans. Chigger infestation on N. fulvescens varied significantly in different environments. The species abundance distribution showed a log-normal distribution pattern. The estimated number of chigger species on N. fulvescens was 126 species.
Two new sesquiterpenoids from endophytic fungus J3 isolated from Mangrove Plant Ceriops tagal
Yan-Bo Zeng,Hai-Gang Gu,Wen-Jian Zuo,Li-Li Zhang,Hong-Jin Bai,Zhi-Kai Guo,Peter Proksch,Wen Li Mei,Hao Fu Dai 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.5
Two new sesquiterpenoids, named 2a-hydroxyxylaranolB (1) and 4b-hydroxyxylaranol B (2), togetherwith a known diterpenoid 3,4-seco-sonderianol (3) wereisolated from the fermentation of endophytic fungus J3 ofCeriops tagal. Their structures were elucidated based onspectroscopic methods including 1D and 2D NMR(HMQC, 1H-1H COSY and HMBC). All compounds wereevaluated for their cytotoxic activities by MTT method,and compound 3 exhibited cytotoxic activities againstK562, SGC-7901, and BEL-7402 cell lines.
Full-scale testing and modeling of the mechanical behavior of shield TBM tunnel joints
Wen-qi Ding,Yi-cheng Peng,Zhi-guo Yan,Bi-wei Shen,He-hua Zhu,Xin-xin Wei 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.3
For shield TBM (Tunnel Boring Machine) tunnel lining, the segment joint is the most critical component for determining the mechanical response of the complete lining ring. To investigate the mechanical behavior of the segment joint in a water conveyance tunnel, which is different from the vehicle tunnel because of the external loads and the high internal water pressure during the tunnel’s service life, full-scale joint tests were conducted. The main advantage of the joint tests over previous ones was the definiteness of the loads applied to the joints using a unique testing facility and the acquisition of the mechanical behavior of actual joints. Furthermore, based on the test results and the theoretical analysis, a mechanical model of segment joints has been proposed, which consists of all important influencing factors,including the elastic-plastic behavior of concrete, the pre-tightening force of the bolts and the deformations of all joint components, i.e., concrete blocks, bolts and cast iron panels. Finally, the proposed mechanical model of segment joints has been verified by the aforementioned full-scale joint tests.