Improved dielectric properties and energy density of PVDF composites using PVP engineered BaTiO3 nanoparticles

Xiaojun Zhu,Yu Dai 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.7

This work systematically investigates the effect of modifier polyvinylpyrrolidone (PVP) on the microstructure, dielectric and energy storage properties of BaTiO3/PVDF composites. The results demonstrate that the BaTiO3 nanoparticles modified by PVP are uniformly dispersed in the composites, and the defects including cracks and voids are obviously decreased in contrast to the composites with unmodified BaTiO3 nanoparticles. Due to the enhanced interfacial polarization, the composites with BaTiO3@PVP show improved dielectric properties compared with the composites with unmodified BaTiO3 nanoparticles. For instance, at 1 kHz, the dielectric constant and dielectric loss of the composite with 50 vol% of BaTiO3@PVP nanoparticles are 80.4 and 0.085, while of which the BaTiO3/PVDF are 35 and 0.265, respectively. The discharge energy density of the composites is largely improved with PVP engineered BaTiO3 nanoparticles. The composite with 30 vol% BaTiO3@PVP achieves a discharged energy density of 4.06 J/cc at 240 kV/mm, which is 116% larger than that of pure PVDF (1.88 J/cc). This research provides an effect modifier to prepare high performance dielectric materials.

Study of upfront surgery versus neoadjuvant chemotherapy followed by interval debulking surgery for patients with stage IIIC and IV ovarian cancer, SGOG SUNNY (SOC-2) trial concept

Rong Jiang,Jianqing Zhu,김재원,Jihong Liu,Kazuyoshi Kato,김희승,Yuqin Zhang,Ping Zhang,Tao Zhu,Daisuke Aoki,Aijun Yu,Xiaojun Chen,Xipeng Wang,Ding Zhu,Wei Zhang,Huixun Jia,Ting-Yan Shi,Wen Gao,Sheng Yin,Yan 대한부인종양학회 2020 Journal of Gynecologic Oncology Vol.31 No.5

Background: Two randomized phase III trials (EORTC55971 and CHORUS) showed similarprogression-free and overall survival in primary or interval debulking surgery in ovariancancer, however both studies had limitations with lower rate of complete resection and lack ofsurgical qualifications for participating centers. There is no consensus on whether neoadjuvantchemotherapy followed by interval debulking surgery (NACT-IDS) could be a preferred approachin the management of advanced epithelial ovarian cancer (EOC) in the clinical practice. Methods: The Asian SUNNY study is an open-label, multicenter, randomized controlled,phase III trial to compare the effect of primary debulking surgery (PDS) to NACT-IDS instages IIIC and IV EOC, fallopian tube cancer (FTC) or primary peritoneal carcinoma (PPC). The hypothesis is that PDS enhances the survivorship when compared with NACT-IDS inadvanced ovarian cancer. The primary objective is to clarify the role of PDS and NACT-IDS inthe treatment of advanced ovarian cancer. Surgical quality assures include at least 50% of nogross residual (NGR) in PDS group in all centers and participating centers should be nationalcancer centers or designed ovarian cancer section or those with the experience participatingsurgical trials of ovarian cancer. Any participating center should be monitored evaluatingthe proportions of NGR by a training set. The aim of the surgery in both arms is maximalcytoreduction. Tumor burden of the disease is evaluated by diagnostic laparoscopy orpositron emission tomography/computed tomography scan. Patients assigned to PDS groupwill undergo upfront maximal cytoreductive surgery within 3 weeks after biopsy, followed by6 cycles of standard adjuvant chemotherapy. Patients assigned to NACT group will undergo 3cycles of NACT-IDS, and subsequently 3 cycles of adjuvant chemotherapy. The maximal timeinterval between IDS and the initiation of adjuvant chemotherapy is 8 weeks. Major inclusioncriteria are pathologic confirmed stage IIIC and IV EOC, FTC or PPC; ECOG performancestatus of 0 to 2; ASA score of 1 to 2. Major exclusion criteria are non-epithelial tumors as wellas borderline tumors; low-grade carcinoma; mucinous ovarian cancer. The sample size is 456subjects. Primary endpoint is overall survival. Trial Registration: ClinicalTrials.gov Identifier: NCT02859038

A phase II trial of cytoreductive surgery combined with niraparib maintenance in platinum-sensitive, secondary recurrent ovarian cancer: SGOG SOC-3 study

Ting-Yan Shi,Sheng Yin,Jianqing Zhu,Ping Zhang,Jihong Liu,Libing Xiang,Yaping Zhu,Sufang Wu,Xiaojun Chen,Xipeng Wang,Yin-Cheng Teng,Tao Zhu,Aijun Yu,Yingli Zhang,Yanling Feng,He Huang,Wei Bao,Yanli Li 대한부인종양학회 2020 Journal of Gynecologic Oncology Vol.31 No.3

Background: In China, secondary cytoreductive surgery (SCR) has been widely used in ovarian cancer (OC) over the past two decades. Although Gynecologic Oncology Group-0213 trial did not show its overall survival benefit in first relapsed patients, the questions on patient selection and effect of subsequent targeting therapy are still open. The preliminary data from our pre-SOC1 phase II study showed that selected patients with second relapse who never received SCR at recurrence may still benefit from surgery. Moreover, poly(ADP-ribose) polymerase inhibitors (PARPi) maintenance now has been a standard care for platinum sensitive relapsed OC. To our knowledge, no published or ongoing trial is trying to answer the question if patient can benefit from a potentially complete resection combined with PARPi maintenance in OC patients with secondary recurrence. Methods: SOC-3 is a multi-center, open, randomized, controlled, phase II trial of SCR followed by chemotherapy and niraparib maintenance vs chemotherapy and niraparib maintenance in patients with platinum-sensitive second relapsed OC who never received SCR at recurrence. To guarantee surgical quality, if the sites had no experience of participating in any OC-related surgical trials, the number of recurrent lesions evaluated by central-reviewed positron emission tomography–computed tomography image shouldn't be more than 3. Eligible patients are randomly assigned in a 1:1 ratio to receive either SCR followed by 6 cycles of platinum-based chemotherapy and niraparib maintenance or 6 cycles of platinum-based chemotherapy and niraparib maintenance alone. Patients who undergo at least 4 cycles of chemotherapy and must be, in the opinion of the investigator, without disease progression, will be assigned niraparib maintenance. Major inclusion criteria are secondary relapsed OC with a platinum-free interval of no less than 6 months and a possibly complete resection. Major exclusion criteria are borderline tumors and non-epithelial ovarian malignancies, received debulking surgery at recurrence and impossible to complete resection. The sample size is 96 patients. Primary endpoint is 12-month non-progression rate. Trial Registration: ClinicalTrials.gov Identifier: NCT03983226

Numerical analysis on stability of express railway tunnel portal

Xiaojun Zhou,Hongyun Hu,Bo Jiang,Yuefeng Zhou,Yong Zhu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.57 No.1

On the basis of the geological conditions of high and steep mountainous slope on which an exit portal of an express railway tunnel with a bridge-tunnel combination is to be built, the composite structure of the exit portal with a bridge abutment of the bridge-tunnel combination is presented and the stability of the slope on which the express railway portal is to be built is analyzed using three dimensional (3D) numerical simulation in the paper. Comparison of the practicability for the reinforcement of slope with in-situ bored piles and diaphragm walls are performed so as to enhance the stability of the high and steep slope. The safety factor of the slope due to rockmass excavation both inside the exit portal and beneath the bridge abutment of the bridge-tunnel combination has been also derived using strength reduction technique. The obtained results show that post tunnel portal is a preferred structure to fit high and steep slope, and the surrounding rock around the exit portal of the tunnel on the high and steep mountainous slope remains stable when rockmass is excavated both from the inside of the exit portal and underneath the bridge abutment after the slope is reinforced with both bored piles and diaphragm walls. The stability of the high and steep slope is principally dominated by the shear stress state of the rockmass at the toe of the slope; the procedure of excavating rockmass in the foundation pit of the bridge abutment does not obviously affect the slope stability. In-situ bored piles are more effective in controlling the deformation of the abutment foundation pit in comparison with diaphragm walls and are used as a preferred retaining structure to uphold the stability of slope in respect of the lesser time, easier procedure and lower cost in the construction of the exit portal with bridge-tunnel combination on the high and steep mountainous slope. The results obtained from the numerical analysis in the paper can be used to guide the structural design and construction of express railway tunnel portal with bridge-tunnel combination on high and abrupt mountainous slope under similar situations.

Effect of the blade loading distribution on hydrodynamic performance of a centrifugal pump with cylindrical blades

Xiaojun Li,Panlong Gao,ZuChao Zhu,Yi Li 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3

The effect of the blade loading distribution on head, radial force and pressure pulsation of a low specific-speed centrifugal pump with cylindrical impeller blades were investigated in the present study. Blade shapes were obtained by adopting the 1D inverse design method, impellers with different blade loading curves were obtained while the distribution of the blade loading was carefully tailored. Threedimensional URANS simulation method based on the Shear stress transport (SST) k-ω turbulence model was employed for the analyzation of flow patterns. Numerical results including the pressure distribution and velocity profile were validated by comparing with the available experimental data, and an acceptable agreement was obtained. Three typical parameters of the blade loading curve, including the location of the fore-loading point (m pre ), location of the aft-loading point (m post ) and slope of the rectilinear segment (K), were analyzed. Results showed that the well-designed blade loading curve, such as the fore-loading impeller, can effectively reduce the pressure pulsation amplitude and the radial force. The significant effect of the variation of the aft-loading point on pump hydrodynamic performance was also investigated. Meanwhile, pressure and velocity distributions at different slopes of the blade loading curves show that the fore-loading impeller produces more uniform flow issuing from the impeller than that of the pump with aft-loading impeller, thus reduces the radial force and pressure pulsation of the pump.

An Efficient Markov Chain Based Channel Model for 6G Enabled Massive Internet of Things

( Wei Yang ),( Xiaojun Jing ),( Hai Huang ),( Chunsheng Zhu ),( Qiaojie Jiang ),( Dongliang Xie ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.11

Accelerated by the Internet of Things (IoT), the need for further technical innovations and developments within wireless communications beyond the fifth generation (B5G) networks is up-and-coming in the past few years. High altitude platform station (HAPS) communication is expected to achieve such high levels that, with high data transfer rates and low latency, millions of devices and applications can work seamlessly. The HAPS has emerged as an indispensable component of next-generations of wireless networks, which will therefore play an important role in promoting massive IoT interconnectivity with 6G. The performance of communication and key technology mainly depend on the characteristic of channel, thus we propose an efficient Markov chain based channel model, then analyze the HAPS communication system's uplink capability and swing effect through experiments. According to the simulation results, the efficacy of the proposed scheme is proven to meet the requirements of ubiquitous connectivity in future IoT enabled by 6G.

Generalized-extended-state-observer-based Sliding-mode Control for Buck Converter Systems

Lan Zhou,Xiaojun Yi,Zhuang Jiang,Zhu Zhang,Jinhua She 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.12

This paper presents a generalized-extended-state-observer (GESO)-based sliding-mode control (SMC) method to deal with mismatched parameter uncertainty and reference-input mutation for a class of DC-DC buck converter systems (BCS). First, a GESO is designed to estimate the total disturbance together with the system state. Then, by choosing an appropriate disturbance-compensation gain, a composite SMC law is designed to attenuate the influence of the parameter uncertainty and reference input mutation on the system output. Both the stability criterion and deign procedure of the system are given. Finally, simulation results show that the designed GESO-based SMC system for the DC-DC BCS is robustly stable and achieves both satisfactory transient and steady-state performance. Comparisons demonstrate that the proposed method provides better transient and steady-state performance for both disturbance rejection and tracking control than either conventional SMC or ESO-based control approach does.

Weak compressibility effects on the pressure fluctuation at RSI in a high-speed centrifugal pump

Shaolong Wang,Xiaoping Chen,Xiaojun Li,BaoLing Cui,Zu-chao Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

This study presents large eddy simulation of high-speed centrifugal pump at approximate quarter load (0.23 Q d ) and design load (Q d ) conditions. Two liquid models, including weak compressible and incompressible assumptions, are considered to investigate the weak compressibility effects (WCE) on the pressure fluctuation at rotor-stator interaction (RSI). Researches show that the performance is slightly increased by the WCE at both the flow rates, which deviate from the experimental data within 5 %. There is a phase deviation between the pressure fluctuation of the two assumptions. The amplitudes of pressure fluctuation and pressure spectra are affected by the WCE, especially in the guide vane channel far away from the tongue. The first and second frequencies of pressure spectra are 12 and 6 times the rotation frequency, respectively, which are insensitive to the WCE. The influence of WCE on the pressure fluctuation and pressure spectra is significant at 0.23 Q d and gradually weakened at Q d .

AMPK alleviates high uric acid-induced Na+-K+-ATPase signaling impairment and cell injury in renal tubules

Jing Xiao,Sibo Zhu,Haochen Guan,Haochen Guan,Fengqin Li,Xiaoli Zhang,Hui Guo,Xiaojun Wang,Zhibin Ye 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

One of the mechanisms in hyperuricemia (HUA)-induced renal tubular injury is the impairment of Na+-K+-ATPase (NKA) signaling, which further triggers inflammation, autophagy, and mitochondrial dysfunction and leads to cell injury. Here, we used RNA sequencing to screen the most likely regulators of NKA signaling and found that the liver kinase B1(LKB1)/adenosine monophosphate (AMP)-activated protein kinase (AMPK)/ mammalian target of rapamycin (mTOR) pathway was the most abundantly enriched pathway in HUA. AMPK is a key regulator of cell energy metabolism; hence, we examined the effect of AMPK on HUA-induced dysregulation of NKA signaling and cell injury. We first detected AMPK activation in high uric acid (UA)-stimulated proximal tubular epithelial cells (PTECs). We further found that sustained treatment with the AMPK activator 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR), but not the AMPK inhibitor Compound C, significantly alleviated UA-induced reductions in NKA activity and NKA α1 subunit expression on the cell membrane by reducing NKA degradation in lysosomes; sustained AICAR treatment also significantly alleviated activation of the NKA downstream molecules Src and interleukin-1β (IL-1β) in PTECs. AICAR further alleviated high UA-induced apoptosis, autophagy, and mitochondrial dysfunction. Although AMPK activation by metformin did not reduce serum UA levels in hyperuricemic rats, it significantly alleviated HUAinduced renal tubular injury and NKA signaling impairment in vivo with effects similar to those of febuxostat. Our study suggests that AMPK activation may temporarily compensate for HUA-induced renal injury. Sustained AMPK activation could reduce lysosomal NKA degradation and maintain NKA function, thus alleviating NKA downstream inflammation and protecting tubular cells from high UA-induced renal tubular injury.

An experimental study on the cavitation vibration characteristics of a centrifugal pump at normal flow rate

Yi Li,Guangwei Feng,Xiaojun Li,Qiaorui Si,ZuChao Zhu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.10

Cavitation is a challenging flow abnormality that leads to undesirable effects on the energy performance of the centrifugal pump and the reliable operation of the pump system. The onset and mechanism of a phenomenon that results in unsteady cavitation must be realised to ensure a reliable operation of pumps under the cavitation state. This study focuses on cavitation instability at normal flow rate, at which point the unsteady cavitation occurs as the available net positive suction head (NPSHa) falls below 5.61 m for the researched pump. An ameliorative algorithm–united algorithm for cavitation vibration analysis is proposed on the basis of short time Fourier transform (STFT) and Wigner–Ville distribution (WVD). The STFT–WVD method is then tested using vibration data measured from the centrifugal pump. The relationship between vibration and suction performance indicates that the inception and development of cavitation can be effectively detected by the distribution and intensity of the united algorithm at the testing points. Intermediate frequency components at approximately 6 kHz fluctuate initially with the development of cavitation. A time–frequency characteristic is found to be conducive to monitoring the cavitation performance of centrifugal pumps.