A self-powered β-Ga2O3/CsCu2I3 heterojunction photodiode responding to deep ultraviolet irradiation

Gao Ang,Jiang Weiyu,Ma Guoliang,Liu Zeng,Li Shan,Yan Zuyong,Sun Weiming,Zhang Shaohui,Tang Weihua 한국물리학회 2022 Current Applied Physics Vol.33 No.-

In this paper, a lead-free halide perovskite CsCu2I3 film with high stability was prepared by the anti-solvent assisted crystallization method. Then, we coupled it with Ga2O3 to prepare a corresponding heterojunction deep ultraviolet (UV) photodetector. After testing, we concluded that the photodetector is sensitive to 254 nm UV light. The photodetector has good reproducibility, and has an ultra-high photo-to-dark current ratio (PDCR) of more than 105. In addition, under a bias of 10 V and an illuminated intensity of 200 μW/cm2, the responsivity (R) and specific detectivity (D*) reached 20 mA/W and 107 cm Hz1/2 W 1 (Jones), and the external quantum efficiency (EQE) is 10%. Meanwhile, the prepared photodetector could operate at zero bias, i.e., self-powered operation, along with a photocurrent of about 1 nA under illumination with UV light intensity of 200 μW/cm2.

A Study of Wheel Tread Spalling Problem of DF21 locomotive

Ma Weihua,Luo Shihui 한국철도학회 2008 한국철도학회 학술발표대회논문집 Vol.- No.-

A Study of Wheel Tread Spalling Problem of $DF_{21}$ Locomotive

Weihua, Ma,Shihui, Luo The Korean Society for Railway 2008 International Journal of Railway Vol.1 No.2

$DF_{21}$ diesel locomotive was designed to satisfy the requirement of Kunming Meter track and the 2Co self-guided radial bogie was used to suit the complex curve track. There are totally 12 locomotives was served on the track. The first two locomotives were devotion running on the track since April 2003, the wheel tread splling was occurred on the middle wheel set of the two locomotives after running nearly 150 thousands km on the track of the two locomotives at August 2004. The dynamic analysis was carried out to find the reason. The wheel set longitudinal vibration resonance phenomenon was existed on the locomotive dynamic performance, and this was caused by the too big longitudinal stiffness of the journal box bar on the middle wheel set. Wheel set longitudinal vibration resonance maybe an important reason of lead to wheel tread spalling. The corresponding mend methods were put forward from the point of view of wheel set longitudinal vibration resonance. All the wheel tread of the 12 locomotives on the middle wheel set were in good condition and not occurred the wheel tread spalling after the mend till December 2007 after 350 thousands km were finished. The mechanism of the wheel tread splling and corresponding mend method was discussed in detail in this paper.

A Styudy of Wheel Tread Spalling Problem of DF<SUB>21</SUB> Locomotive

Ma Weihua,Luo Shihui 한국철도학회 2008 International Journal of Railway Vol.1 No.2

DF₂₁ diesel locomotive was designed to satisfy the requirement of Kunming Meter track and the 2Co self-guided radial bogie was used to suit the complex curve track. There are totally 12 locomotives was served on the track. The first two locomotives were devotion running on the track since April 2003, the wheel tread splling was occurred on the middle wheel set of the two locomotives after running nearly 150 thousands km on the track of the two locomotives at August 2004. The dynamic analysis was carried out to find the reason. The wheel set longitudinal vibration resonance phenomenon was existed on the locomotive dynamic performance, and this was caused by the too big longitudinal stiffness of the journal box bar on the middle wheel set. Wheel set longitudinal vibration resonance maybe an important reason of lead to wheel tread spalling. The corresponding mend methods were put forward from the point of view of wheel set longitudinal vibration resonance. All the wheel tread of the 12 locomotives on the middle wheel set were in good condition and not occurred the wheel tread spalling after the mend till December 2007 after 350 thousands km were finished. The mechanism of the wheel tread splling and corresponding mend method was discussed in detail in this paper.

Electrophysiological and behavioral responses of Asian and European honeybees to pear flower volatiles

Ma Weihua,Long Denglong,Wang Yi,Li Xinyu,Huang Jiaxing,Shen Jinshan,Su Wenting,Jiang Yusuo,Li Jie 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

Honeybee pollination behavior is influenced by flower volatiles, which honeybees sense via olfactory receptors. Honeybees are only weakly attracted to pear flowers. To investigate the potential reasons, we extracted and determined the floral volatile compounds from three pear cultivars (Su, Ya, and Xuehua) using headspace solidphase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC–MS). The effects of pear flower volatiles on the Asian honeybee (Apis cerana cerana Fabricius) and the European honeybee (Apis mellifera ligustica Spinola) were determined by electroantennogram (EAG) assays and behavioral tests in a three-arm olfactometer. Among the 76 flower volatiles detected with GC–MS, 21 were found in all three pear cultivars, accounting for approximately 70% of the total volatile content. 3-Methyl-1-butanol and (+)-limonene volatiles had the highest relative content. Five compounds elicited strong EAG responses in both bee species: 2-methylbu tyraldehyde, 1-nonanal, 6-methyl-5-hepten-2-one, 3-methyl-1-butanol, and (+)-limonene. Neither bee species showed positive taxis to these volatiles. In behavioral tests, A. mellifera ligustica showed a low preference for 6-methyl-5-hepten-2-one (20%, 400 µg/µL) and 2-phenethyl alcohol (16.7%, 400 µg/µL). Apis cerana cerana showed a low preference for 6-methyl-5-hepten-2-one (6.7%, 400 µg/µL) and 1-nonanal (10%, 400 µg/µL), whereas its preferences for 3-methyl-1-butanol (43.3%, 400 µg/µL) and α-farnesene (40%, 400 µg/µL) were similar to that for the control. Therefore, a lack of attractive volatile compounds could explain why honeybees are only weakly attracted to pear flowers. Therefore, to achieve acceptable pollination in pear orchards, we suggest using flower-scent sugar syrup feeding and a saturation pollination strategy.

Study on the Black Phenotype Mutants of Adult and Pupa of Helicoverpa armigera

Mo Wang,Jianhong Li,Weihua Ma,Lizhen Chen 한국응용곤충학회 2005 한국응용곤충학회 학술대회논문집 Vol.2005 No.05

Evaluation of Neck Lymph Node Metastasis on Contrast-Enhanced Ultrasound: An Animal Study

Zheng Cui,Yi Gao,Weihua Wang,Zhenghua Zhu,Zhaoxin Ma 대한이비인후과학회 2017 Clinical and Experimental Otorhinolaryngology Vol.10 No.1

Objectives. To assess the performance of contrast-enhanced ultrasound (CEUS) intended to differentiate hyperplastic from malignant neck lymph nodes in an animal model. Methods. Twenty-four New Zealand rabbits were randomly divided into two groups: neck lymph node metastasis group (12 rabbits) and reactive hyperplastic lymph node group (12 rabbits). Tongue VX2 carcinoma with cervical lymph node metastasis was induced in 12 rabbits by injecting VX2 carcinoma suspension into the left tongue submucosa. Hyperplastic neck lymph nodes were induced by injecting egg yolk in the submandibular region of the rabbits in hyperplastic group. CEUS were performed in both groups before and after intravenous administration of SonoVue. The site, number, echogenicity, longitudinal and transverse nodal dimensions, patterns of enhancement of the neck lymph nodes were observed and recorded. Results. In both groups only one lymph node was found in the left (tumor) side of the neck. CEUS found 12 of 12 metastatic lymph nodes in metastasis group, and diagnosed 11 of 12 lymph nodes as metastatic. Histopathologic analysis revealed metastatic lesions in all 12 rabbits, each with one lymph node, and all 12 lymph nodes in hyperplastic group is inflammation lymph nodes. All 12 cases in the hyperplastic group showed centripetal homogeneous enhancement while in the metastasis group one case showed centripetal homogeneous enhancement, three cases showed centrifugal heterogeneous enhancement, and eight cases showed diffused heterogeneous enhancement. Only one lymph node was dissected on the left side of the neck in each rabbit in both groups. Conclusion. CEUS can play a role in discriminating metastatic from hyperplastic lymph nodes in head and neck carcinoma.

Rapid Separation of Gossypol from Cottonseeds by a Solid-Phase Synthetic Method

Wu, Hankui,Xu, Zhiyong,Ma, Ya,Qi, He,Cao, Jinxia,Li, Gang,Chen, Yong,Yang, Weihua Korean Chemical Society 2016 대한화학회지 Vol.60 No.3

Facile Fabrication of Hollow Li3PO4 Catalyst via Ostwald Ripening

Jihai Zhang,Dongyu Wang,Weihua Ma 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.1

Hollow inorganic nanostructures are important due to their applications in energy storage and conversion, catalysis, gas sensing, and biomedicine. Li3PO4 is used as an isomerization catalyst for propylene oxide to selectively give allyl alcohol. We used a facile template-free method to synthesize hollow Li3PO4 nanoparticles with size range of 500 nm to 1500 nm. The effect of concentration, agitation, ripening temperature and the ratio of starting reagents on the hollowing process is investigated. The most important factor to influence the hollowness was found to be the ratio of lithium ion to phosphate ion; as the ratio increases, the hollowness of the particles increases. When this ratio reached 3, the hollow nanostructures become dominant. As an isomerization catalyst for propylene oxide, 4-Li3PO4 exhibited the highest conversion and best selectivity of allyl alcohol. The hydroxide ion of the precursor is adsorbed on the surface of the Li3PO4 particles which results in different surface basicity.

Mangiferin loaded magnetic PCEC microspheres: preparation, characterization and antitumor activity studies in vitro

WenJing Xiao,Jun Hou,Jie Ma,BoTao Yu,JianDong Ren,WeiHua Jin,Juan Wu,DeZhi Zheng,KaiHua Fan 대한약학회 2021 Archives of Pharmacal Research Vol.44 No.8

Mangiferin is a promising effective chemopreventiveagent against various tumors. However, itsclinical use is limited by poor water solubility and lowbioavailability. In this article, mangiferin loaded magneticPCEC microspheres (MG-MS) were designed, characterizedand the antitumor activity of MG-MS was evaluatedin vitro. The magnetic nanoparticles (MNP) were synthesizedvia the high-temperature reaction of ironacetylacetonate in phenyl ether in the presence of oleic acidand oleylamine. Poly (ε-caprolactone)-poly (ethyleneglycol)-poly (ε-caprolactone) (PCL-PEG-PCL, PCEC)copolymers were formed by ring-opening copolymerizationof ε-CL initiated by PEG-diol using Sn(Oct)2 as acatalyst and MG-MS were prepared by solvent diffusionmethod. MNP, PCEC copolymer, and MG-MS werecharacterized by GPC, TEM, XRD, FT-IR, 1H-NMP andMalvern Laser Particle Sizer. Meanwhile, the antiproliferativeactivity in vitro and in vitro release behavior of thismicrospheres were studied in detail. The results indicatethat the obtained magnetic microspheres might have greatpotential as an effective carrier for mangiferin used incancer chemotherapy.