A Robust and Accurate Traveltime Calculation from Frequency-domain Two-way Wave-equation Modeling Algorithm

Qin, Yilong,Zhang, Zhongjie,Shin, Changsoo,Ko, Seungwon,Seo, Youngtak,Han, Uk,Chen, Yun 한국암반공학회 2004 Geosystem engineering Vol.7 No.1

We improve the accuracy and stability of traveltime calculation method using frequency-domain modeling algorithm. We perform a parameter analysis to obtain the optimum combination of frequency and damping factor and thus improve the accuracy of traveltime. Then we obtain the empirical formula for our numerical algorithm. Lastly, we propose the adaptive frequency and the adaptive damping factor for an inhomogeneous model to eliminate the distortion in the traveltime contour. Two-dimensional numerical examples verify that the proposed algorithm gives a much smaller traveltime error and a better traveltime contour for the complex model. Compared to the other two methods, this algorithm computes traveltime that is close to a directly transmitted wave. We demonstrated our algorithm on 2D IFP Marmousi models, and the numerical results show that our algorithm is a faster traveltime calculation method of a directly transmitted wave for imaging the subsurface and transmission tomography.

Enhancing Electrocatalytic Production of H2O2 by Modulating Coordination Environment of Cobalt Center

Guoling Wu,Zhongjie Yang,Tianlin Zhang,Yali Sun,Chang Long,Yaru Song,Shengbin Lei,Zhiyong Tang 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.8

As an environmentally friendly oxidant, H2O2 is widely utilized in various fields; however, its production methods remain limited to the chemical anthraquinone process. Alternatively, electrocatalytic oxygen reduction possesses numerous notable advantages (e.g., cost-effectiveness, small-scale, and distributed nature). As electrocatalytic oxygen reduction has been widely investigated in the fields of fuel cells and metal-air batteries, the mechanism of the 2e?-ORR pathway for producing H2O2 is not sufficiently clear. Herein, we explore the effect of the cobalt (Co) coordination environment on the electrochemical production of H2O2. The detailed investigation on N-, P-, and S-coordinated Co catalysts (Co1N1N3, Co1P1N3, and Co1S1N3) demonstrates that changing the coordination environment evidently affects the H2O2 selectivity, and the S-coordinated Co exhibits the best catalytic performance. This finding would lead to the design and selection of catalysts at atomic level for producing H2O2 via electrocatalytic oxygen reduction.

Influences of Wire Diameters on Output Power in Electromagnetic Energy Harvester

Yan Peng,Lan Zhang,Zhongjie Li,Songyi Zhong,Yong Liu,Shaorong Xie,Jun Luo 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.1

In this paper, we systematically investigate how the wire diameter affects the output performance of electromagnetic energy harvesters. The harvesters with the same structure but different coils mainly comprised of a magnet array, two coil arrays, a pair of springs and a housing. Different discrete wire diameters of coils are selected to compare the output performance and explore the optimal value. We first set up the theoretical model of the configuration to predict optimal wire diameter and conduct simulations to observe open-circuit voltage and output power, and find the hypothetically optimal diameter leading to the best performance. Subsequently, we fabricate a series of prototypes and conduct four groups of experiments from the following aspects for comparison purposes: constant frequency excitation, frequency sweep, impedance matching and charging capacitors, and validate the theoretically estimated value. When we operate the prototypes under the excitation of 20 Hz, 1.0 g, the maximum average power of 37.45 mW is generated with the best wire diameter, at least 1.62 times as high as that in other cases. The results of capacitor charging experiments, i.e., charging rate, further validate the output power trend. This study can be of great significance for power density improvement in electromagnetic energy harvesters.

Therapeutic responses to chemotherapy or immunotherapy by molecular subtype in bladder cancer patients: A meta-analysis and systematic review

Shunde Wang,Xiaoyu Yuan,Zhongjie Shen,Jiaming Zhao,Baishu Zheng,Junyong Zhang,Chengguo Ge 대한비뇨의학회 2023 Investigative and Clinical Urology Vol.64 No.3

To systematically evaluate the differences in therapeutic response to chemotherapy or immunotherapy between different molecular subtypes of bladder cancer (BC). A comprehensive literature search was performed up to December 2021. Consensus clusters 1 (CC1), CC2 and CC3 molecular subtypes were used to perform meta-analysis. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the therapeutic response by fix-effect modeling. Eight studies involving 1,463 patients were included. For immunotherapy, CC3 showed the highest response rate (CC1 vs. CC3: OR=0.52, 95% CI=0.34–0.78, p=0.002; CC2 vs. CC3: OR=0.42, 95% CI=0.28-0.62, p<0.001), which was mainly reflected in the highest response rate to atezolizumab (CC1 vs. CC3: OR=0.47, 95% CI=0.29–0.75, p=0.002; CC2 vs. CC3: OR=0.38, 95% CI=0.24–0.59, p<0.001). For chemotherapy, CC3 had the lowest response rate to the overall chemotherapy (CC1 vs. CC3: OR=2.05, 95% CI=1.23–3.41, p=0.006; CC2 vs. CC3: OR=2.48, 95% CI=1.50–4.10, p<0.001). Compared with CC2, CC3 responded poorly to both neo-adjuvant chemotherapy (NAC) (OR=1.93, 95% CI=1.09–3.41, p=0.020) and chemoradiation therapy (CRT) (OR=6.07, 95% CI=1.87–19.71, p<0.001). Compared with CC1, CC3 only showed a poorer response to CRT (OR=4.53, 95% CI=1.26–16.27, p=0.020), and no difference in NAC. Our study suggested that molecular classifications are important predictors of cancer treatment outcomes of BC patients and could identify subgroup patients who are most likely to benefit from specific cancer treatments.

The influences of lateral leakage on hysteresis effects in flexible organic light-emitting diodes array

Xiong Zhiyong,Wen Zhuoqi,Cui Zhongjie,Mei Shiliang,He Haiyang,Duan Zhongtao,Zhang Wanlu,Xie Fengxian,Guo Ruiqian 한국물리학회 2023 Current Applied Physics Vol.45 No.-

Hysteresis effects in self-luminous devices like organic light-emitting diodes (OLEDs) and perovskite light-emitting diodes (PeLEDs) have been discovered recently, besides emerging in thin film transistors (TFTs). However, the influences of lateral leakage caused by next-door devices on hysteresis effects in flexible OLEDs array have rarely been demonstrated. To mitigate the impact of lateral leakage and figure out the detailed relationship with hysteresis effects, a series of experiments for OLEDs array involving p-doping in holes transport layer (HTL) were employed. It is found that the lateral leakage and hysteresis effects have a trade-off exhibition, which means stronger lateral leakage has induced weaker hysteresis effects. In order to get rid of the role of lateral leakage, the experiments with mono blue devices were also performed to substantiate the intrinsic hysteresis effects existence. The research opens the possibility of considering more internal relationships between different performances on self-luminous arrays for their actual application.

ENHANCED VISIBLE-LIGHT-DRIVEN PHOTOCATALYTIC DEGRADATION PERFORMANCE OF CIP ON BiVO 4 – Bi 2 WO 6 NANO-HETEROJUNCTION PHOTOCATALYSTS

SHAOFANG SUN,WEISHENG GUAN,XIAN ZHANG,ZHONGJIE ZHANG,YAN YAN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2

The removal of CIP from the environment has become a mandatory issue. In our paper, we haverealized the visible-light-driven degradation of CIP on the BiVO 4 – Bi 2 WO 6 nano-heterojunctionphotocatalysts. The synthesized photocatalysts were characterized by X-ray difraction (XRD),¯eld emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM),high-resolution transmission electron microscopy (HRTEM), ultraviolet-visible (UV-Vis) ab-sorption spectra and photoluminescence (PL) spectra. Compared with the single-phase BiVO 4and Bi 2 WO 6 counterparts, BiVO 4 – Bi 2 WO 6 nano-heterojunction photocatalysts show enhancedphotocatalytic degradation activities in visible-light-driven CIP degradation. Particularly, whenRðBi 2 WO 6 =BiVO 4 Þ ¼ 10 wt:% , the products exhibit the highest CIP degradation ratio in 60 min of76.8% under visible light illumination. The tentative mechanism of the interface charge transfer(IFCT) efect in the BiVO 4 – Bi 2 WO 6 heterojunction structure is also discussed by using the bandposition calculation.

Continuous Conduction Mode Soft-Switching Boost Converter and its Application in Power Factor Correction

Cheng, Miao-miao,Liu, Zhiguo,Bao, Yueyue,Zhang, Zhongjie The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

Continuous Conduction Mode Soft-Switching Boost Converter and its Application in Power Factor Correction

Miao-miao Cheng,Zhiguo Liu,Yueyue Bao,Zhongjie Zhang 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

Essential oil of Citrus limon Osbeck: An insecticidal natural product against Cryptolestes pusillus SchÖnherr

Jie Yu,Shi Tianyu,Yang Dong,Zhang Zhongjie 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.1

This study investigated the insecticidal activity and mechanism of action of essential oil from Citrus limon Osbeck (C. limon oil). The fumigation method was used to determine the insecticidal activity of different concentrations of C. limon oil against adult Cryptolestes pusillus (C. pusillus). In addition, the effect of C. limon oil on the organs of adult C. pusillus was studied. The results showed that when the concentration of C. limon oil reached 0.6 μL/cm 3 , following fumigation for 4, 8, 12, 16, 20, and 24 h, the corrected mortality rates of adult C. pusillus were 13 %, 30 %, 47 %, 95 %, 97 %, and 100 %, respectively. Furthermore, C. limon oil caused vacuolization in the digestive tract and adipose cells, thus, as a plant-based insecticide, it has strong research and application value.

Culture-Positive Spontaneous Ascitic Infection in Patients with Acute Decompensated Cirrhosis: Multidrug-Resistant Pathogens and Antibiotic Strategies

Jing Liu,Yanhang Gao,Xianbo Wang,Zhiping Qian,Jinjun Chen,Yan Huang,Zhongji Meng,Xiaobo Lu,Guohong Deng,Feng Liu,Zhiguo Zhang,Hai Li,Xin Zheng 연세대학교의과대학 2020 Yonsei medical journal Vol.61 No.2

Purpose: This study investigated multidrug-resistant (MDR) pathogens and antibiotic strategies of culture-positive spontaneousascitic infection (SAI) in patients with acute decompensated cirrhosis. Materials and Methods: We retrospectively analyzed 432 acute decompensated cirrhotic patients with culture-positive SAI from11 teaching hospitals in China (January 2012 to May 2018). A Cox proportional hazards model analysis was conducted to identifyindependent predictors of 28-day mortality. Results: A total of 455 strains were isolated from 432 ascitic culture samples. Gram-negative bacteria (GNB), gram-positive bacteria(GPB), and fungi caused 52.3, 45.5, and 2.2% of all SAI episodes, respectively. Episodes were classified as nosocomial (41.2%), healthcare-related (34.7%), and community-acquired (24.1%). Escherichia coli (13.4%) and Klebsiella pneumoniae (2.4%) were extendedspectrumβ-lactamase producing isolates. The prevalence of methicillin-resistant Staphylococcus aureus was 1.1%. Ceftazidime,cefepime, aztreonam, and amikacin were recommended as first-line antibiotics agents for non-MDR GNB infections; piperacillin/tazobactam and carbapenems for MDR GNB in community-acquired and healthcare-related or nosocomial infections, respectively;and vancomycin or linezolid for GPB infections, regardless of drug-resistance status. Multivariate analysis revealed days ofhospital stay before SAI, upper gastrointestinal bleeding, white blood cell count, alanine aminotransferase, serum creatinine concentration,total bilirubin, and international normalized ratio as key independent predictors of 28-day mortality. Conclusion: MDR pathogens and antibiotic strategies were identified in patients with acute decompensated cirrhosis with culture-positive SAI, which may help optimize therapy and improve clinical outcomes.