Impact of Cu2O doping on high dielectric properties of CuO ceramics

Dan-Dan Wang,Feng-Zi Zhou,Jing-Xiao Cao,Li-Ben Li,Guo-Ling Li 한국물리학회 2017 Current Applied Physics Vol.17 No.5

Single-phase CuO ceramic samples were prepared with the starting nano powders of CuO þ xCu2O (x ¼ 0, 1, 3, 7% in mole ratio) via solid state reaction method, and characterized by X-ray diffraction, Raman scattering and scanning electron microscopy. For all the samples, the temperature dependences of dielectric constants and losses were measured at the frequencies of 102, 103, 104, 105 and 106 Hz, respectively. With increasing doping content of Cu2O, a strong correlation is demonstrated at given temperature and frequency between the measured dielectric constants and the unit-cell volumes of CuO. The strong correlation is argued in terms of the change in densities of Cu]O defects (e.g. Cu/O vacancies and/or interstitial Cu impurities) due to Cu2O doping, which is supported by the formation energies of Cu]O defects and the corresponding unit-cell volume from first-principles calculations. The high dielectric constant (~103e105) of CuO ceramic is therefore attributed to the reduction in resistance due to Cu/O defects in the grain by Maxwell-Wagner mechanism.

Vibrio alginolyticus MviN is a LuxO-regulated Protein and Affects Cytotoxicity Towards Epithelioma Papulosum Cyprini(EPC)Cells

( Xiao Dan Cao ),( Qi Yao Wang ),( Qin Liu ),( Huan Liu ),( Hong Hong He ),( Yuan Xing Zhang ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.2

Gamma radiation shielding properties of poly (methyl methacrylate) / Bi₂O₃ composites

Cao, Da,Yang, Ge,Bourham, Mohamed,Moneghan, Dan Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11

This work investigated the gamma-ray shielding performance, and the physical and mechanical properties of poly (methyl methacrylate) (PMMA) composites embedded with 0-44.0 wt% bismuth trioxide (Bi₂O₃) fabricated by the fast ultraviolet (UV) curing method. The results showed that the addition of Bi₂O₃ had significantly improved the gamma shielding ability of PMMA composites. Mass attenuation coefficient and half-value layer were examined using five gamma sources (Cs-137, Ba-133, Cd-109, Co-57, and Co-60). The high loading of Bi₂O₃ in the PMMA samples improved the micro-hardness to nearly seven times that of the pure PMMA. With these enhancements, it was demonstrated that PMMA/Bi₂O₃ composites are promising gamma shielding materials. Furthermore, the fast UV curing exerts its great potential in significantly shortening the production cycle of shielding material to enable rapid manufacturing.

Selection and identification of single-domain antibody against Peste des Petits Ruminants virus

Dan Liu,Lingxia Li,Xiaoan Cao,Jinyan Wu,Guoyu Du,Youjun Shang 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.4

Background: Peste des petits ruminants (PPR) is an infectious disease caused by the peste des petits ruminants virus (PPRV) that mainly produces respiratory symptoms in affected animals, resulting in great losses in the world's agriculture industry every year. Single-domain variable heavy chain (VHH) antibody fragments, also referred to as nanobodies, have high expression yields and other advantages including ease of purification and high solubility. Objectives: The purpose of this study is to obtain a single-domain antibody with good reactivity and high specificity against PPRV. Methods: A VHH cDNA library was established by immunizing camels with PPRV vaccine, and the capacity and diversity of the library were examined. Four PPRV VHHs were selected, and the biological activity and antigen-binding capacity of the four VHHs were identified by western blot, indirect immunofluorescence, and enzyme-linked immunosorbent assay (ELISA) analyses. ELISA was used to identify whether the four VHHs were specific for PPRV, and VHH neutralization tests were carried out. ELISA and western blot analyses were used to identify which PPRV protein was targeted by VHH2. Results: The PPRV cDNA library was constructed successfully. The library capacity was greater than 2.0 × 106 cfu/mL, and the inserted fragment size was approximately 400 bp to 2000 bp. The average length of the cDNA library fragment was about 1000 bp, and the recombination rate was approximately 100%. Four single-domain antibody sequences were selected, and proteins expressed in the supernatant were obtained. The four VHHs were shown to have biological activity, close affinity to PPRV, and no cross-reaction with common sheep diseases. All four VHHs had neutralization activity, and VHH2 was specific to the PPRV M protein. Conclusions: The results of this preliminary research of PPRV VHHs showed that four screened VHH antibodies could be useful in future applications. This study provided new materials for inclusion in PPRV research.

Utility of VEGF and sVEGFR-1 in Bronchoalveolar Lavage Fluid for Differential Diagnosis of Primary Lung Cancer

Cao, Chao,Sun, Shi-Fang,Lv, Dan,Chen, Zhong-Bo,Ding, Qun-Li,Deng, Zai-Chun Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.4

Published data have shown that the levels of vascular endothelial growth factor (VEGF) and soluble VEGF receptor-1 (sVEGFR-1) in plasma and pleural effusion might be usefulness for lung cancer diagnosis. Here, we performed a prospective study to investigate the utility of VEGF and sVEGFR-1 in bronchoalveolar lavage fluid (BALF) for differential diagnosis of primary lung cancer. A total of 56 patients with solitary pulmonary massed by chest radiograph or CT screening were enrolled in this study. BALF and plasma samples were obtained from all patients and analyzed for VEGF and sVEGFR-1 using a commercially available sandwich ELISA kit. The results showed that the levels of VEGF in BALF were significantly higher in patients with a malignant pulmonary mass compared with patients with a benign mass (P < 0.001). However, no significant difference of sVEGFR-1 in BALF was found between malignant and non-malignant groups (P = 0.43). With a cut-off value of 214 pg/ml, VEGF showed a sensitivity and specificity of 81.8% and 84.2%, respectively, in predicting the malignant nature of a solitary pulmonary mass. Our study suggests that VEGF is significantly increased in BALF among patients with lung cancer than in benign diseases. Measurement of VEGF in BALF might be helpful for differential diagnosis of primary lung cancer.

Online monitoring of IGBT junction temperature based on V_ce measurement

Cao, Han,Ning, Puqi,Chai, Xiaoguang,Zheng, Dan,Kang, Yuhui,Wen, Xuhui The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

In this paper, an online junction temperature monitoring method based on the on-state voltage under high collector current density measurements for IGBT power modules is proposed. Unlike the conventional junction temperature monitoring method, the presented method can extract the junction temperature during operation without altering the modulation strategy or topology of the converter. The proposed method is verified by simulations and the JEDEC-51 standard recommended approach. To accurately extract the on-state voltage during operation, a measurement circuit that combines the advantages of both the active MOSFET clamp and the diode clamp is designed and tested. It has been shown to have good accuracy and a rapid response time. After the calibration results are obtained, the presented method is applied to a three-phase voltage source converter controlled by a closed-loop SVPWM modulation strategy.

Facile Synthesis and High Anode Performance of Carbon Fiber-Interwoven Amorphous Nano-SiO_<i>x</i>/Graphene for Rechargeable Lithium Batteries

Nguyen, Dan Thien,Nguyen, Cao Cuong,Kim, Jong-Seon,Kim, Je Young,Song, Seung-Wan American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.21

<P>We present the first report on carbon fiber-interwoven amorphous nano-SiO<SUB><I>x</I></SUB>/graphene prepared by a simple and facile room temperature synthesis of amorphous SiO<SUB><I>x</I></SUB> nanoparticles using silica, followed by their homogeneous dispersion with graphene nanosheets and carbon fibers in room temperature aqueous solution. Transmission and scanning electron microscopic imaging reveal that amorphous SiO<SUB><I>x</I></SUB> primary nanoparticles are 20–30 nm in diameter and carbon fibers are interwoven throughout the secondary particles of 200–300 nm, connecting SiO<SUB><I>x</I></SUB> nanoparticles and graphene nanosheets. Carbon fiber-interwoven nano-SiO<SUB>0.37</SUB>/graphene electrode exhibits impressive cycling performance and rate-capability up to 5C when evaluated as a rechargeable lithium battery anode, delivering discharge capacities of 1579–1263 mAhg<SUP>–1</SUP> at the C/5 rate with capacity retention of 80% and Coulombic efficiencies of 99% over 50 cycles, and nearly sustained microstructure. The cycling performance is attributed to synergetic effects of amorphous nano-SiO<SUB><I>x</I></SUB>, strain-tolerant robust microstructure with maintained particle connectivity and enhanced electrical conductivity.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-21/am4034763/production/images/medium/am-2013-034763_0010.gif'></P>

Functional Definition of LuxS, an Autoinducer-2 (AI-2) Synthase and Its Role in Full Virulence of Streptococcus suis Serotype 2

Min Cao,Youjun Feng,Changjun Wang,Feng Zheng,Ming Li,Hui Liao,Yinghua Mao,Xiuzhen Pan,Jing Wang,Dan Hu,Fuquan Hu,Jiaqi Tang 한국미생물학회 2011 The journal of microbiology Vol.49 No.6

Quorum sensing is a widespread chemical communication in response to fluctuation of bacterial population density, and has been implicated into bacterial biofilm formation and regulation of expression of virulence factors. The luxS gene product, S-ribosylhomocysteinase, catalizes the last committed step in biosynthetic pathway of autoinducer 2 (AI-2), a signaling molecule for inter-species quorum sensing. We found a luxS homologue in 05ZYH33, an epidemic strain of Streptococcus suis serotype 2 (SS2) in China. A luxS null mutant (ΔluxS) of 05ZYH33 strain was obtained using an approach of homologous recombination. LuxS was determined to be required for AI-2 production in 05ZYH33 strain of S. suis 2. Inactivation of luxS gene led to a wide range of phenotypic changes including thinner capsular walls, increased tolerance to H_2O_2, reduced adherence capacity to epithelial cells, etc. In particular, loss of LuxS impaired dramatically its full virulence of SS2 in experimental model of piglets, and functional complementation restored it nearly to the level of parent strain. Genome-wide transcriptome analyses suggested that some known virulence factors such as CPS are down-regulated in the ΔluxS mutant, which might in part explain virulence attenuation by luxS deletion. Similarly, 29 of 71 genes with different expression level were proposed to be targets candidate regulated by LuxS/AI-2-dependent quorum sensing.

Improved Dyeing of Meta-aramid Based on Particle Flow Dyeing Mechanism Using Hot-pressing Dyeing Method

Xin Chen,Dan Sheng,Honghui Xia,Weilin Xu,Bo Deng,Genyang Cao 한국섬유공학회 2020 Fibers and polymers Vol.21 No.12

In this study, a combined dyeing method by integrating the advantages of both carrier dyeing and hot-pressingdyeing was utilized for the dyeing of meta-aramid. A rapid dyeing with increased mechanical properties of the fibers wasachieved for the meta-aramid fiber. A so-called particle flow mechanism involving both N,N-dimethylacetamide (DMAc)and dye molecules was proposed to explain the accelerating effect of this unique dyeing method. The mechanical propertiesand thermodynamic stability of the fiber after hot-pressing were both increased. XRD results showed increasedcorresponding fiber crystallinity. TEM showed that the disperse dyes were well dispersed in DMAc. Cross-sectional opticalphotographs of dyed fibers revealed that the dyes were successfully carried into the interior of the fiber under the synergiceffect of temperature and pressure. Combined with hot-pressing dyeing, the dyeing cycle for the meta-aramid could begreatly shortened and the amounts of dyes and carriers could be significantly reduced.

Intelligent energy-saving operation of wheel loader based on identifiable materials

Bing-wei Cao,Xinhui Liu,Wei Chen,Kuo Yang,Dan Liu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

This study applies image recognition technology to the shovel loading operation of a wheel loader for the first time. In the proposed method, the wheel loader can automatically select the corresponding engine power curve according to different identifiable materials, thus achieving intelligent energy saving. This study first analyzed the working resistance of the wheel loader, and the analysis results provided theoretical support to the energy-saving operation of the wheel loader. The shovel loading test was carried out for different materials. The test results validated the feasibility of intelligent energy-saving operation of the wheel loader based on identifiable materials. A neural network algorithm based on material identification model was then built and verified, whose material identification rate was 92 %. The model was used as the carrier, and the wheel loader-operating characteristics were considered in view of the existing engine energy-saving mode. Finally, the boom cylinder pressure and bucket angle were used as feedback to future discussion about the intelligent energy-saving operation of the wheel loader. The basic conditions for subsequent designs of wheel loaders are provided.