Excellent microwave absorption of FeCo/ZnO composites with defects in ZnO for regulating the impedance matching

Bao, Xiukun,Wang, Xiaolei,Zhou, Xinao,Shi, Guimei,Xu, Ge,Yu, Jin,Guan, Yinyan,Zhang, Yajing,Li, Da,Choi, Chuijin Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.769 No.-

<P><B>Abstract</B></P> <P>FeCo/ZnO composites have been successfully prepared through liquid-phase reduction process for the formation of FeCo polyhedrons and sequentially thermal decomposition of colloidal mixture of FeCo and Zn(Ac)<SUB>2</SUB>·2H<SUB>2</SUB>O under nitrogen atmospheres. ZnO nanoparticles are homogeneously deposited on the surface of FeCo polyhedrons and the level of oxygen-vacancy defects in ZnO can be elevated with the increase of ZnO content. By comparison with FeCo polyhedrons, FeCo/ZnO composites exhibit excellent microwave absorption. The optimal RL value can reach −34.8 dB at 14.8 GHz and effective bandwidth (RL < −10 dB) is 5.1 GHz in the frequency range of 12.4–17.5 GHz with a matching thickness of 1.5 mm. The integrated bandwidth with RL < −10 dB can reach 14.1 GHz covering 3.4–17.5 GHz. Theory analysis demonstrates the interfacial polarization, dipole polarization and high conductivity due to oxygen-vacancy defects in FeCo/ZnO composites contribute to enhancement of dielectric loss capacity, which is more favorable for impedance matching.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The preferable impedance matching of FeCo/ZnO composites can be achieved by regulating the ZnO content. </LI> <LI> The optimal reflection loss (RL) can reach −34.8 dB with a matching thickness of 1.5 mm. </LI> <LI> The effective bandwidth with RL < −10 dB achieve 14.1 GHz covering 3.4–17.5 GHz with integrated thickness of 1.5–5 mm. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Bauschinger Effect or Kinematic Hardening: Bridging Microstructure and Continuum Mechanics

Bao-Guang Zhang,Xiao-Ming Zhang,Hai-Tao Liu,Hua-Bing Li 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2

As a strong and low-priced austenite stabilizer, nitrogen (0.085 wt%) was deliberately added into a hot-rolled Fe-0.2C-5Mn TRIP steel for optimizing the strength–ductility balance. Nitrogen addition can not only increase austenite fraction (> 50%), but also favor the improvement of austenite stability due to its partition behavior from ferrite to austenite during intercritical annealing. Besides, the low annealing temperature (635 °C) and nitrogen addition result in the simultaneous precipitation of cementite (size, 21–396 nm) and carbonitride (size, 7–193 nm) in ferrite and at grain boundaries, which can effectively increase the yield strength through precipitation strengthening (33–63 and 41–61 MPa, respectively). Furthermore, the sufficient interstitial solute originated from N addition as well as the discontinuous TRIP effect benefits the strong serrated flow behavior and multi-peak strain hardening behavior. As a result, the strong TRIP effect together with precipitation strengthening is believed to be responsible for the excellent strength–ductility balance of present steel annealed for 3 h, demonstrating a high tensile strength of 1043 MPa, outstanding total elongation of 43.3% and superior product of strength and elongation (PSE) of 44.8 GPa%.

Stiffness design and mechanical performance analysis of transverse leaf spring suspension

Bao Zhang,Hongnan Wang,Zhi Li,Tangyun Zhang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

Suspension stiffness affects vehicle comfort and handling performance. The stiffness optimization of the transverse leaf spring suspension can be achieved by adjusting the distance between the two central installation positions of the leaf spring. This method can avoid changing the structure of the leaf spring, reduce the difficulty of product development, and shorten the product development cycle, so this type of suspension has high engineering application value. In the paper, a finite element model of the transverse leaf spring is established, and the characteristics of the stiffness, deformation and stress of the leaf spring with the distance are studied. According to the objectives of suspension dynamic deflection, body roll angle and leaf spring reliability, the distance matching design is carried out, and the design scheme is experimentally verified. The research shows that the stiffness of the leaf spring under the opposite direction loading condition is greater than that of the same direction loading condition, and the difference between the two data increases with the increase of the distance. When the distance is 800 mm, the stiffness of the suspension is 102.1 N/mm under the same loading and 220.4 N/mm under reverse loading, the maximum stress is 1487 MPa, the dynamic deflection 39.2 mm, and the maximum body roll angle is less than 6.0°. All of the above indicators meet the design requirements. The research results provide theoretical basis and reference for the design of a transverse leaf spring suspension.

Codelivery of hydrophilic and hydrophobic drugs in a microneedle patch for the treatment of skin pigmentation

Li Qin Zhang,Xiao Peng Zhang,Yu Ying Hao,Bao Li Zhang,Xin Dong Guo 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.88 No.-

When overexposed to ultraviolet B (UVB) irradiation, skin can cause a series of abnormal reactions, suchas excessive pigmentation and solar elastosis. In order to better treat the skin after overexposed to UVB,we designed a dissolving microneedles (MNs) loading hydrophilic ascorbic acid and hydrophobic vitaminA palmitate to achieve codelivery. Here, we confirmed that MNs had enough mechanical strength toinsert the skin and two drugs were delivered subcutaneously in sequence in vitro. In white guinea pigs,surface observation and histological observation results confirmed that two drugs by MNs transdermaldelivery were better than topical administration in the treatment of UVB-damaged skin. The MNs providea method of loading different drugs into the needles and advance the development of transdermal drugdelivery.

Effects of Wind Generation Uncertainty and Volatility on Power System Small Signal Stability

Li-Bao Shi,Li Kang,Liang-Zhong Yao,Shi-Yao Qin,Rui-Ming Wang,Jin-Ping Zhang 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

This paper discusses the impacts of large scale grid-connected wind farm equipped with permanent magnet synchronous generator (PMSG) on power system small signal stability (SSS) incorporating wind generation uncertainty and volatility. Firstly, a practical simplified PMSG model with rotor-flux-oriented control strategy applied is derived. In modeling PMSG generator side converter, the generator-voltage-oriented control strategy is utilized to implement the decoupled control of active and reactive power output. In modeling PMSG grid side converter, the grid-voltageoriented control strategy is applied to realize the control of DC link voltage and the reactive power regulation. Based on the Weibull distribution of wind speed, the Monte Carlo simulation technique based is carried out on the IEEE 16-generator-68-bus test system as benchmark to study the impacts of wind generation uncertainty and volatility on small signal stability. Finally, some preliminary conclusions and comments are given.

Ozone infusiblization and curing mechanism of polysilazane ceramic precursor fibers

Li Xiaohong,Luo Xiaoyu,Li Jing,Li Jinxia,Yang Jiahao,Ahmad Zahoor,Bao Zhihao,Zhang Xiao,Chen Jianjun 한국세라믹학회 2023 한국세라믹학회지 Vol.60 No.5

An appropriate infusible method plays a vital role as one of the key processes of the fabrication of polymer-derived ceramic fibers. In this work, ozone curing, a novel room temperature controllable curing strategy was used to prepare SiCN ceramic fibers. Some circular pores were observed on the surface of the obtained SiCN ceramic fibers. The tensile strength of the fibers was also investigated. To reveal the ozone-curing mechanisms of the PSZ fibers and the formation process of the circular pores, the FT-IR, SEM, OM, XRD and TG were characterized. The results showed that the Si–H bonds and Si-CH3 groups in the PSZ molecule were oxidized gradually to form oxygen-containing groups such as Si–OH, Si–O-Si and C = O in the ozone curing process, which contributed to the curing and weight gain of the PSZ fibers. Moreover, a hydrolysis reaction between Si-NH-Si and H2O might further accelerate the curing of the PSZ fibers. An unexpected result of the hydrolysis reaction is the formation of some circular pores on the surface layer of the PSZ fibers. This strategy provides a method to design, adjust and control the microstructure and composition of silicon-based ceramic fibers, and the obtained SiCN fibers may be used as catalyst support, bacterial culture and other fields.

Effects of confinement on physiological and psychological responses and expression of interleukin 6 and brain derived neurotrophic factor mRNA in primiparous and multiparous weaning sows

Zhang, Mingyue,Li, Xiang,Li, Jianhong,Sun, Hanqing,Zhang, Xiaohui,Bao, Jun Asian Australasian Association of Animal Productio 2017 Animal Bioscience Vol.30 No.9

Objective: The present study aimed to investigate whether the long-lasting, recurrent restricting of sows leads to the physiological and psychological reaction of discomfort. Methods: Sows (Large White) that had experienced restricting for about 0.5 or 3 years and agematched sows kept in a group housing system (loose sows) were compared. Pupillary light reflex parameters were measured at the weaning stage. Immediately after slaughter, blood samples were taken to measure serum cortisol levels, and the brain was dissected, gene expression in the hippo-campus, frontal cortex and hypothalamus was analyzed. Results: The serum cortisol levels were higher in the confined sows than in the loose sows. The full maturity, but not the young adolescent, confined sows had longer latency time in the onset of pupil constriction than their loose counterparts. Real-time polymerase chain reaction analyses revealed an increased expression of interleukin 6 mRNA in the hippocampus and decreased expression of brain derived neurotrophic factor mRNA in hippocampus and hypothalamus and to a lesser extent in the frontal cortex of the full maturity confined sows, compared with the full maturity loose sows. Conclusion: Taken together, these data indicated that recurrent restricting stress in full maturity sows leads to the physiological and psychological reaction of discomfort.

Microstructure Characteristics, Mechanical Properties and Strain Hardening Behavior of Nitrogen-Bearing Fe-0.2 C-5Mn TRIP Steel

Bao-Guang Zhang,Xiao-Ming Zhang,Hua-Bing Li,Hai-Tao Liu 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3

As a strong and low-priced austenite stabilizer, nitrogen (0.085 wt%) was deliberately added into a hot-rolled Fe-0.2C-5Mn TRIP steel for optimizing the strength–ductility balance. Nitrogen addition can not only increase austenite fraction (> 50%), but also favor the improvement of austenite stability due to its partition behavior from ferrite to austenite during intercritical annealing. Besides, the low annealing temperature (635 °C) and nitrogen addition result in the simultaneous precipitation of cementite (size, 21–396 nm) and carbonitride (size, 7–193 nm) in ferrite and at grain boundaries, which can effectively increase the yield strength through precipitation strengthening (33–63 and 41–61 MPa, respectively). Furthermore, the sufficient interstitial solute originated from N addition as well as the discontinuous TRIP effect benefits the strong serrated flow behavior and multi-peak strain hardening behavior. As a result, the strong TRIP effect together with precipitation strengthening is believed to be responsible for the excellent strength–ductility balance of present steel annealed for 3 h, demonstrating a high tensile strength of 1043 MPa, outstanding total elongation of 43.3% and superior product of strength and elongation (PSE) of 44.8 GPa%.

Effects of Wind Generation Uncertainty and Volatility on Power System Small Signal Stability

Shi, Li-Bao,Kang, Li,Yao, Liang-Zhong,Qin, Shi-Yao,Wang, Rui-Ming,Zhang, Jin-Ping The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.1

This paper discusses the impacts of large scale grid-connected wind farm equipped with permanent magnet synchronous generator (PMSG) on power system small signal stability (SSS) incorporating wind generation uncertainty and volatility. Firstly, a practical simplified PMSG model with rotor-flux-oriented control strategy applied is derived. In modeling PMSG generator side converter, the generator-voltage-oriented control strategy is utilized to implement the decoupled control of active and reactive power output. In modeling PMSG grid side converter, the grid-voltage-oriented control strategy is applied to realize the control of DC link voltage and the reactive power regulation. Based on the Weibull distribution of wind speed, the Monte Carlo simulation technique based is carried out on the IEEE 16-generator-68-bus test system as benchmark to study the impacts of wind generation uncertainty and volatility on small signal stability. Finally, some preliminary conclusions and comments are given.

Evaluation of Several Screening Approaches for Detection of Cervical Lesions in Rural Shandong, China

Zong, Li-Ju,Zhang, You-Zhong,Yang, Xing-sheng,Jiang, Jie,Cui, Bao-Xia,Qiao, Yun-Bo,Li, Li,Jiang, Kan,Zhang, Wen-Jing,Kong, Bei-Hua,Shen, Keng Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.5

Purpose: The study was designed to: (1) investigate the prevalence of high-risk human papillomavirus (HR-HPV) infection and cervical neoplasia; and (2) evaluate clinical performance of visual inspection with acetic acid/ Lugol's iodine (VIA /VILI), Pap smear, high-risk human papillomavirus (HR-HPV) DNA test for detecting cervical intraepithelial neoplasia grade 2 or worse (CIN2+) and (3) explore appropriate screening approach in rural areas of Shandong Province. Materials and Methods: A total of 3,763 eligible women from Yiyuan County in Yimeng mountainous areas of rural Shandong, China, were enrolled and underwent Pap smear, HR-HPV DNA testing by Hybrid Capture 2 (HC2), and VIA /VILI tests. Women positive in any test were referred to colposcopy and biopsy as indicated. Results: The prevalence of HR-HPV infection among all enrolled women was 11.1% and that in healthy women was 9.9%. In total 33 cases of CIN1, 16 cases of CIN2, 6 cases of CIN3 but none of cervical cancer were detected and the crude prevalence of CIN2+ was 0.58%. For detecting CIN2+, the sensitivity of HR-HPV DNA testing, VIA/VILI, Pap smear was 90.9%, 77.3%, 81.8%, respectively. Pap smear had the best specificity of 98.2%, followed by HR-HPV DNA testing with specificity of 89.4%, VIA/VILI had the lowest specificity of 81.2%. Colposcopy referral rate of HR-HPV DNA testing, VIA/VILI, Pap smear was 11.1%, 18.5%, 2.3%, respectively. Conclusions: Our results suggest that HR-HPV DNA testing alone might be appropriate for primary cervical cancer screening in rural low-resource areas of Shandong Province, China.