Synthesis and Sol-Gel Transition of Novel Temperature Responsive ABA Triblock-Graft Copolymers Based on PCL and PEG Analogues

Qinqin Wang,Shouxin Liu,Weijuan Sheng,Naer Guang,Xuan Li 한국고분자학회 2015 Macromolecular Research Vol.23 No.7

Novel hydrophilic, temperature responsive, and biodegradable ABA triblock-graft copolymers, [poly(ε- caprolactone)-g-poly(2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate)]-b-poly(ethylene glycol)-b-[poly(-caprolactone)-g-poly(2-(2-methoxyethoxy) ethyl methacrylate-co-oligo(ethylene glycol) methacrylate)] ([PCL-g-P(MEO2MA-co-OEGMA)]-b-PEG-b-[PCL-g-P(MEO2MA-co-OEGMA)]) (tBGs), were synthesized via a combination of ring-opening polymerization (ROP) of ε-caprolactone (εCL) and α-chloro-ε-caprolactone (αClεCL) in the presence of PEG and atom transfer radical polymerization (ATRP) of MEO2MA and OEGMA. Temperature responsive P(MEO2MA-co-OEGMA) graft chains on the hydrophobic PCL block of PCL-b-PEG-b-PCL not only improved the solubility of PCL-b-PEG-b-PCL in water, but also endowed it with temperature sensitivity. The synthesized temperature responsive triblock-graft copolymers formed well-defined core-shell micelles as the temperature was above their LCST (ca. 35 oC), with hydrophilic PEG block as shell, P(MEO2MA-co-OEGMA) graft chains on the PCL block and hydrophobic PCL block aggregates as core. The micellization induced by temperature for the tBGs in aqueous solutions had been investigated by transmittance measurement, laser particle size measurement, 1H NMR in D2O, DLS and TEM. For a given tBG5 aqueous solution (30 wt%), a weak hydrogel was available at 35 oC, and its sol-gel transition temperature gradually decreased with increasing concentration. In addition, the tBG5 hydrogels loaded with anethole were used for hydrophobic drug release, and in vitro the sustained release of anethole from the tBG5 hydrogels was examined, which is a significant for anethole for their biomedical applications.

Recent progress on the traditional and emerging catalysts for propane dehydrogenation

Fushan Feng,Haiyuan Zhang,Shaoqi Chu,Qinqin Zhang,Chao Wang,Guang-Jian Wang,Fang Wang,Liancheng Bing,Dezhi Han 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-

Propene is an important chemical raw material with continuously growing demand from the propenedownstream industry. Compared with the traditional catalytic cracking process and steam cracking ofnaphtha, the propane dehydrogenation (PDH) process is an attractive alternative to efficiently producehigh-purity propene. Presently, the traditional Pt-based and Cr-based catalysts for PDH are mainly usedin commercial processes. And the non-noble metal catalysts and carbon catalysts for PDH also receiveincreasing attention with the development of research both from academia and industry. In this review,the recent progress on the traditional catalysts, the emerging non-noble metal catalysts, and carbon catalystswas summarized, together with the discussion of the key research issues and development directionof these PDH catalysts. This review could provide the theoretical and technical foundation fordeveloping novel high-efficiency PDH catalysts.

Trophic strategy of diverse methanogens across a river-to-sea gradient

Bingchen Wang,Fanghua Liu,Shiling Zheng,Qinqin Hao 한국미생물학회 2019 The journal of microbiology Vol.57 No.6

Methanogens are an important biogenic source of methane, especially in estuarine waters across a river-to-sea gradient. However, the diversity and trophic strategy of methanogens in this gradient are not clear. In this study, the diversity and trophic strategy of methanogens in sediments across the Yellow River (YR) to the Bohai Sea (BS) gradient were investigated by high-throughput sequencing based on the 16S rRNA gene. The results showed that the diversity of methanogens in sediments varied from multitrophic communities in YR samples to specific methylotrophic communities in BS samples. The methanogenic community in YR samples was dominated by Methanosarcina, while that of BS samples was dominated by methylotrophic Methanococcoides. The distinct methanogens suggested that the methanogenic community of BS sediments did not originate from YR sediment input. High-throughput sequencing of the mcrA gene revealed that active Methanococcoides dominated in the BS enrichment cultures with trimethylamine as the substrate, and methylotrophic Methanolobus dominated in the YR enrichment cultures, as detected to a limited amount in in situ sediment samples. Methanosarcina were also detected in this gradient sample. Furthermore, the same species of Methanosarcina mazei, which was widely distributed, was isolated from the area across a river-to-sea gradient by the culture-dependent method. In summary, our results showed that a distribution of diverse methanogens across a river-to-sea gradient may shed light on adaption strategies and survival mechanisms in methanogens.

Adaptive robust control for fully electric pitch system of tank with dynamic friction compensation

Darui Lin,Xiuye Wang,Guolai Yang,Shusen Yuan,Qinqin Sun 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.10

This article addresses a problem of dynamic friction compensation for fully electric pitch system of tank based on modified LuGre model. Aiming to design a controller to realize friction modeling and compensating of fully electric pitch system of tank in large range of motion speeds. First, a nonlinear mathematical model including modified friction model and time-varying disturbance is established for fully electric pitch system of tank. Second, a disturbance compensation robust feedback term is designed to compensate the time-varying disturbance to reduce the impact of the disturbance on the control performance by adaptive estimation of the upper bound of the unmodeled disturbance. Third, the uncertainty parameters and friction state of the system are estimated and the adaptive control law combined with friction compensation is designed to reduce the sensitivity of the system to parameter uncertainty and nonlinear friction. Fourth, the global stability of the system is proved by Lyapunov stability theory. Finally, a virtual prototype model of tank moving based on friction disturbance and road excitation is established. The co-simulation results show that the proposed method can accurately estimate and compensate model parameters, nonlinear friction states and disturbances, and has the advantages of high control precision, good stability and strong robustness.

Wavelet packet transform and improved complete ensemble empirical mode decomposition with adaptive noise based power quality disturbance detection

Yu Mei,Yajing Wang,Xiangke Zhang,Shiqi Liu,Qinqin Wei,Zhenhai Dou 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8

Given the low accuracy of power quality disturbance (PQD) detection, a PQD detection method based on the wavelet packet transform (WPT) and improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) is proposed in this paper. First, the wavelet packet transform is used to preprocess the signal to suppress noise interference. Then, ICEEMDAN technology is adopted to calculate the local mean value by adding adaptive noise. In addition, different intrinsic mode functions (IMFs) are obtained through residual subtraction. Furthermore, the effective IMFs are calculated by the permutation entropy method to reduce false modal components and to suppress residual noise. Finally, a Hilbert transform (HT) is performed to extract the detection signal parameters. The obtained results demonstrate that this method can improve the detection accuracy and PQD speed, which results in a strong anti-noise capability.

The impacts of LPCVD wrap-around on the performance of n-type tunnel oxide passivated contact c-Si solar cell

Zhou Ying,Tao Ke,Liu Aimin,Rui Jia,Bao Jianhui,Sun Yufeng,Yang Sanchuan,Wang Qinqin,Zhang Qiang,Yang Songbo,Cao Yujia,Qu Hui 한국물리학회 2020 Current Applied Physics Vol.20 No.7

In this paper, Tunnel Oxide Passivated Contact (TOPCon) silicon solar cells with the industrial area (244.32 cm2) are fabricated on N-type silicon substrates. Both the ultra-thin tunnel oxide layer and phosphorus doped polycrystalline silicon (polysilicon) thin film are prepared by the LPCVD system. The wrap-around of polysilicon is observed on the surface of borosilicate glass (BSG). The polysilicon wrap-around can form a leakage current path, thus degrades the shunt resistance of solar cells, and leads to the degradation of solar cell efficiency. Different methods are adopted to treat the polysilicon wrap-around and improve shunt resistance of solar cells. The experimental results indicate that a chemical etching method can effectively solve the problem of polysilicon wrap-around and improve the performance of solar cells. Finally, a conversion efficiency of 22.81% has been achieved by our bifacial TOPCon solar cells, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2 and FF of 81.62%.