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      • KCI등재

        A Novel Method to Improve the Dispersibility of Silicon Nitride Powders in Aqueous Media

        Bingjie Xu,Mengxing Li,Qi Chen,Pengfei Liu,Baosong Xu,Ben Qiu,Liang Xu,Zhao Han 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9

        The present study describes a novel method to improve the dispersibility of silicon nitride powders in aqueous media. Specifically, a new Si3N4@g-C3N4 core–shell composite material was synthesized via annealing the mixture of silicon nitride and melamine under a nitrogen atmosphere using heating method. The effects of various initial mass ratios of Si3N4 and melamine on the structure and dispersibility of the composite were systematically investigated. The results of X-ray photoelectron spectroscopy and transmission electron microscope demonstrated that as-obtained Si3N4@g-C3N4 composite powders possess the core–shell structure, whereas the zeta potential and sedimentation analysis showed that they exhibit good dispersion in aqueous media. Furthermore, the colloidal dispersion of the composite powders is most stable when the initial mass ratio of Si3N4 and melamine is 100 : 3. The coated g-C3N4 could be completely removed in a cryogenic nitrogen atmosphere. The proposed process is expected to provide novel avenues for the study of dispersion of other inorganic powders.

      • KCI등재

        Comparison between laparoscopic and abdominal radical hysterectomy for stage IB1 and tumor size <2 cm cervical cancer with visible or invisible tumors: a multicentre retrospective study

        Pengfei Li,Lan Chen,Yan Ni,Jiaqi Liu,Donglin Li,Jianxin Guo,Zhihua Liu,Shuangling Jin,Yan Xu,Zhiqiang Li,Lu Wang,Xiaonong Bin,Jinghe Lang,Ping Liu,Chunlin Chen 대한부인종양학회 2021 Journal of Gynecologic Oncology Vol.32 No.2

        Objective: To compare 5-year disease-free survival (DFS) and overall survival (OS) rates oflaparoscopic radical hysterectomy (LRH) and abdominal radical hysterectomy (ARH) forstage IB1 and tumor size <2 cm with visible or invisible tumors. Methods: We retrospectively compared the oncological outcomes of 1,484 cervical cancerpatients with IB1 and tumor size <2 cm on final pathology, who received ARH (n=899) or LRH(n=585) between January 2004 and December 2016. Patients were divided into visible tumorsubgroup (ARH: n=668, LRH: n=444) and invisible tumor subgroup (ARH: n=231, LRH:n=141) according to tumor type. Results: LRH and ARH showed similar 5-year DFS and OS rates (93.3% vs. 93.1%, p=0.997;96.2% vs. 97.5%, p=0.351) in total study population. LRH was not associated with worse5-year DFS rate (hazard ratio [HR]=0.96; 95% confidence interval [CI]=0.58–1.58; p=0.871)or OS rate (HR=1.37; 95% CI=0.65–2.89; p=0.409) by multivariable analysis. In the visibletumor subgroups, LRH and ARH showed similar 5-year DFS and OS rates (91.9% vs. 91.9%,p=0.933; 95.0% vs. 96.9%, p=0.276), and LRH was not associated with worse 5-year DFS orOS rate (p=0.804, p=0.324). In the invisible tumor subgroups, LRH and ARH also showedsimilar 5-year DFS and OS rates (97.3% vs. 97.1%, p=0.815; 100% vs. 99.5%, p=0.449), andLRH was not associated with worse 5-year DFS rate (p=0.723). Conclusions: Among patients with stage IB1 and tumor size <2 cm, whether the tumor isvisible or not, the oncological outcomes of LRH and ARH among cervical cancer patients arecomparable. This suggests that LRH may be suitable for stage IB1 and tumor size <2 cm withvisible or invisible tumors.Trial Registration: International Clinical Trials Registry Platform Identifier: CHiCTR180017778

      • KCI등재

        Characterization and functional study of juvenile hormone diol kinase gene in Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

        Pengfei Xie,Zhenghui Li,Xu Ding,Yaodong Zhou,Jing-Lan Liu 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

        The brown planthopper, Nilaparvata lugens (Stål) is an important pest in rice. It has been widely recognized that the juvenile hormone (JH) is regulated by its hydrolase, which includes juvenile hormone esterase (JHE), juvenile hormone epoxide hydrolase (JHEH) and juvenile hormone diol kinase (JHDK). In this paper, we cloned the gene of Jhdk and the gene expression at different stages of N. lugens was analysed, and the relationship with Jhe and Jheh was studied after silencing the jhdk gene of N. lugens (Nljhdk) through double-stranded RNA (dsRNA) feeding. We also explored the expression of the three JH hydrolase after indoxacarb treatments. RT-PCR was used to amplify the full length Jhdk cDNA, and the Nljhdk gene was expressed throughout all the development periods tested and showed the lowest level at the 4th instar and the highest in the 5th instar. The expression level of Nljhdk in male adults was higher than that of female adults. Through feeding, dsRNA against Nljhdk successfully knocked down the target gene, which had no significant effect on the expression of the jhe gene of N. lugens (Nljhe), while the expression of Nljheh was upregulated. Indoxacarb could inhibit N. lugens reproduction, and the expression level of Nljhe and Nljhdk increased with the increasing of indoxacarb concentration, but the expression of the jheh gene of N. lugens (Nljheh) was reduced. These studies provide a line of experimental evidence in N. lugens to support that Nljhdk encodes the functional protein involved in JH degradation and further showed the relationship of the three hydrolases and the mechanism of indoxacarb inhibition of the fecundity of N. lugens.

      • KCI등재

        Numerical studies on cavitation behavior in impeller of centrifugal pump with different blade profiles

        Pengfei Song,Yongxue Zhang,Cong Xu,Xin Zhou,Jinya Zhang 한국유체기계학회 2015 International journal of fluid machinery and syste Vol.8 No.2

        To investigate the influence of blade profiles on cavitation behavior in impeller of centrifugal pump, a centrifugal pump with five different blade profiles impellers are studied numerically. The impellers with five different blade profiles (single arc, double arcs, triple arcs, logarithmic spiral and linear -variable angle spiral) were designed by the in-house hydraulic design code using geometric parameters of IS 150-125-125 centrifugal pump. The experiments of the centrifugal pump have been conducted to verify numerical simulation model. The numerical results show that the blade profile lines has a weak effect on cavitation inception near blade inlet edge position, however it has the key effect on the development of sheet cavitation in impeller, and also influences the distribution of sheet cavitation in impeller channels. A slight changing of blade setting angle will induce significant difference of cavitation in impeller. The sharp changing of impeller blade setting angle causes obvious cavitation region separation near the impeller inlet close to blade suction surface and much more flow loss. The centrifugal pump with blade profile of setting angle gently changing (logarithmic spiral) has the super cavitation performance, which means smaller critical cavitation number and lower vapor cavity volume fraction at the same conditions.

      • KCI등재

        Research on Calculation Method of Suspension Bridge Internal Force under Random Traffic Load

        Pengfei Wu,Zhichun Fang,Xue Wang,Renyuan Wang,Qiang Xu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

        Suspension bridge is a flexible structure. The weight, location and number of traffic on the bridge will affect the geometric alignment of the bridge. Although the finite element software can analyze the geometric nonlinearity of the bridge, the calculation of random load combination in finite element software is huge. In this paper, based on the deformation coordination, static equilibrium and constitutive model of the bridge, the force expression considering the geometric nonlinearity of the bridge is derived. Finite element software is used to simulate the internal force of components of suspension bridge under train load and vehicle load. The accuracy is verified by comparing the finite element results. Considering the random number of traffics, the random location of traffics, and the random weight of traffics, this paper analyzes the stress state of bridge under the random process of train load and vehicle load respectively. The method in this paper can be well used to analyze the actual stress state of the bridge, and provide a theoretical basis for related calculations.

      • SCOPUSKCI등재

        Numerical studies on cavitation behavior in impeller of centrifugal pump with different blade profiles

        Song, Pengfei,Zhang, Yongxue,Xu, Cong,Zhou, Xin,Zhang, Jinya Korean Society for Fluid machinery 2015 International journal of fluid machinery and syste Vol.8 No.2

        To investigate the influence of blade profiles on cavitation behavior in impeller of centrifugal pump, a centrifugal pump with five different blade profiles impellers are studied numerically. The impellers with five different blade profiles (single arc, double arcs, triple arcs, logarithmic spiral and linear-variable angle spiral) were designed by the in-house hydraulic design code using geometric parameters of IS 150-125-125 centrifugal pump. The experiments of the centrifugal pump have been conducted to verify numerical simulation model. The numerical results show that the blade profile lines has a weak effect on cavitation inception near blade inlet edge position, however it has the key effect on the development of sheet cavitation in impeller, and also influences the distribution of sheet cavitation in impeller channels. A slight changing of blade setting angle will induce significant difference of cavitation in impeller. The sharp changing of impeller blade setting angle causes obvious cavitation region separation near the impeller inlet close to blade suction surface and much more flow loss. The centrifugal pump with blade profile of setting angle gently changing (logarithmic spiral) has the super cavitation performance, which means smaller critical cavitation number and lower vapor cavity volume fraction at the same conditions.

      • SCIESCOPUSKCI등재

        Effects of Adding Essential Oil to the Diet of Weaned Pigs on Performance, Nutrient Utilization, Immune Response and Intestinal Health

        Li, Pengfei,Piao, Xiangshu,Ru, Yingjun,Han, Xu,Xue, Lingfeng,Zhang, Hongyu Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.11

        The objective of this study was to evaluate the effects of adding essential oils to the diet of weaned pigs on performance, nutrient utilization, immune response and intestinal health. A total of 96 weaning pigs ($8.37{\pm}1.58$ kg) were allotted to one of three dietary treatments. The treatments consisted of an unsupplemented basal diet (negative control, NC) or similar diets supplemented with 0.01% of an essential oil product which contained 18% thymol and cinnamaldehyde (EOD) as well as a diet supplemented with 0.19% of an antibiotic mixture which provided 150 ppm chlortetracycline, 80 ppm colistin sulfate and 50 ppm kitasamycin (positive control, PC). Each treatment was provided to eight pens of pigs with four pigs per pen. Over the entire 35 d experiment, ADG and fecal score were improved (p<0.05) for pigs fed the PC and EOD compared with the NC. Dry matter and crude protein digestibility as well as lymphocyte proliferation for pigs fed the PC and EOD diets were increased significantly compared with NC (p<0.05). IGF-I levels in plasma were significantly increased (p<0.05) in pigs fed the PC diet compared with pigs fed the NC diet. Interleukin-6 concentration was lower (p<0.05) and the tumor necrosis factor-${\alpha}$ level was higher (p<0.05) in the plasma of pigs fed the EOD diet than the NC diet. Plasma total antioxidant capacity level increased (p<0.05) in pigs fed the EOD diet compared with pigs fed the NC. Villus height to crypt depth ratio in the jejunum was greater (p<0.05) in pigs fed the PC and EOD diets than the NC. The numbers of E. coli in the cecum, colon and rectum were reduced (p<0.05) in pigs fed the PC and EOD diets compared with the control. In the colon, the ratio of Lactobacilli to E. coli was increased (p<0.05) in pigs fed the EOD diet compared with NC diet. Total aerobe numbers in the rectum were decreased (p<0.05) in pigs fed the PC and EOD diets compared with the control. Collectively, these results indicate that blends of essential oils could be a candidate for use as an alternative to traditional antibiotics in weaning pig diets.

      • KCI등재

        Feasibility of Free-Breathing, Non-ECG-Gated, Black-Blood Cine Magnetic Resonance Images With Multitasking in Measuring Left Ventricular Function Indices

        Peng Pengfei,Yue Xun,Tang Lu,Wu Xi,Deng Qiao,Wu Tao,Cai Lei,Liu Qi,Xu Jian,Huang Xiaoqi,Chen Yucheng,Diao Kaiyue,Sun Jiayu 대한영상의학회 2023 Korean Journal of Radiology Vol.24 No.12

        Objective: To clinically validate the feasibility and accuracy of cine images acquired through the multitasking method, with no electrocardiogram gating and free-breathing, in measuring left ventricular (LV) function indices by comparing them with those acquired through the balanced steady-state free precession (bSSFP) method, with multiple breath-holds and electrocardiogram gating. Materials and Methods: Forty-three healthy volunteers (female:male, 30:13; mean age, 23.1 ± 2.3 years) and 36 patients requiring an assessment of LV function for various clinical indications (female:male, 22:14; 57.8 ± 11.3 years) were enrolled in this prospective study. Each participant underwent cardiac magnetic resonance imaging (MRI) using the multiple breath-hold bSSFP method and free-breathing multitasking method. LV function parameters were measured for both MRI methods. Image quality was assessed through subjective image quality scores (1 to 5) and calculation of the contrast-to-noise ratio (CNR) between the myocardium and blood pool. Differences between the two MRI methods were analyzed using the Bland–Altman plot, paired t-test, or Wilcoxon signed-rank test, as appropriate. Results: LV ejection fraction (LVEF) was not significantly different between the two MRI methods (P = 0.222 in healthy volunteers and P = 0.343 in patients). LV end-diastolic mass was slightly overestimated with multitasking in both healthy volunteers (multitasking vs. bSSFP, 60.5 ± 10.7 g vs. 58.0 ± 10.4 g, respectively; P < 0.001) and patients (69.4 ± 18.1 g vs. 66.8 ± 18.0 g, respectively; P = 0.003). Acceptable and comparable image quality was achieved for both MRI methods (multitasking vs. bSSFP, 4.5 ± 0.7 vs. 4.6 ± 0.6, respectively; P = 0.203). The CNR between the myocardium and blood pool showed no significant differences between the two MRI methods (18.89 ± 6.65 vs. 18.19 ± 5.83, respectively; P = 0.480). Conclusion: Multitasking-derived cine images obtained without electrocardiogram gating and breath-holding achieved similar image quality and accurate quantification of LVEF in healthy volunteers and patients.

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