Graphene oxide nanosheets to improve permeability and selectivity of PIM-1 membrane for carbon dioxide separation

Mengmeng Chen,Faizal Soyekwo,Qiugen Zhang,Chuan Hu,Aimei Zhu,Qinglin Liu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

Polymers of intrinsic microporosity (PIMs) have attracted increasing interest in gas separation membranes due to their high permeability. However, the moderate selectivity limits their wide applications in CO2 separation. Herein we report a facile strategy to improve simultaneously the permeability and CO2 selectivity of PIMs membrane using the prepared PIM-1/graphene oxide (GO) nanosheets mixed matrix membrane. The GO nanosheets improves the hydrophilicity and surface roughness of PIM-1 membrane whereas the uniform assembly of GO nanosheets in the PIM-1 matrix creates the hydrophilic/hydrophobic microphase segregation in the membrane. The as-prepared mixed matrix membrane is also very porous and has a pore size of about 0.78 nm. The combination of these properties significantly contributes to the enhancement of the gas separation performance of PIM-1 membrane, with the resultant membrane exhibiting an exceptionally high CO2 permeability of up to 6169 barrer as well as a high CO2/N2 selectivity of 123.5, which is more than 7 times that of the pure PIM-1 membrane. The developed PIM-1/GO mixed matrix membrane should have a wide application in the CO2 separation.

Analysis of Meteorological Disasters and Its Impact based on Production Function

Chen Yunfeng,Li Lianshui,Cui Mengmeng,Wang Jin 보안공학연구지원센터 2012 International Journal of Hybrid Information Techno Vol.5 No.2

Improved SVR Method for Predicting the Cutting Force of a TBM Cutter Using Linear Cutting Machine Test Data

Mengmeng Hu,Biao Li,Bo Zhang,Ruirui Wang,Lei Chen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

This research introduces a support vector regression (SVR) method to predict the cutting forces acting on the constant cross section (CCS) disc cutter, including the normal force (FN) and rolling force (FR), based on linear cutting machine (LCM) test data. To improve the prediction effect, an improved SVR-Outlier Detection (SVR-OD) method and an Additional Input Variable (AIV) method are proposed. After removing the outliers, 148 typical LCM test samples form the training set. Here, 70 samples from the Hangzhou No.2 Water Supply Channel constitute the test set. The prediction results show that the Root-mean-squared Relative Error (RMRE) values of the normal force and rolling force are 19.5% and 24.8%, respectively, and the corresponding determination coefficients are 0.845 and 0.807, respectively. For the prediction of the peak cutting force with an important reference to tunnel boring machine (TBM) design, the proportions of samples with an Absolute Relative Error (ARE) value of less than 20% for FN and FR are 9/10 and 7/7, respectively. The above prediction results are better than those of the common SVR method; thus, the developed method can effectively simulate the cutting force required by a rock mass with good integrity. The cutting force prediction using LCM test data is feasible and practical. In addition, the comparison of the prediction results between the improved SVR and common SVR methods shows that the improved SVR-OD and AIV methods play an active role in improving the prediction accuracy of the SVR method.

Biomaterial-Based CRISPR/Cas9 Delivery Systems for Tumor Treatment

Mengmeng Li,Fenglei Chen,Qian Yang,Qinglai Tang,Zian Xiao,Xinying Tong,Ying Zhang,Lanjie Lei,Shisheng Li 한국생체재료학회 2024 생체재료학회지 Vol.28 No.00

CRISPR/Cas9 gene editing technology is characterized by high specificity and efficiency, and has been applied to the treatment of human diseases, especially tumors involving multiple genetic modifications. However, the clinical application of CRISPR/Cas9 still faces some major challenges, the most urgent of which is the development of optimized delivery vectors. Biomaterials are currently the best choice for use in CRISPR/Cas9 delivery vectors owing to their tunability, biocompatibility, and efficiency. As research on biomaterial vectors continues to progress, hope for the application of the CRISPR/Cas9 system for clinical oncology therapy builds. In this review, we first detail the CRISPR/Cas9 system and its potential applications in tumor therapy. Then, we introduce the different delivery forms and compare the physical, viral, and non-viral vectors. In addition, we analyze the characteristics of different types of biomaterial vectors. We further review recent research progress in the use of biomaterials as vectors for CRISPR/Cas9 delivery to treat specific tumors. Finally, we summarize the shortcomings and prospects of biomaterial-based CRISPR/Cas9 delivery systems.

Tectono-magmatic evolution of the Mesozoic granodiorite and their diorite enclaves in Shulan Area, Jilin, China

Mengmeng Li,Jingdang Liu,Tianyi Liang,Chen Li,Dejun Bao 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.1

The Mesozoic granodiorite and their diorite enclaves in the Shulan area have been investigated to understand the petrographic characteristics and elemental geochemistry and to further interpret the petrogenesis and paleotectonic environment. The petrography, mineral component, zircon U-Pb age, and major and trace element contents of 9 granodiorite host rock samples and 9 diorite enclave samples were analyzed. Results show host rock and the enclave both present of medium-fine subhedral and porphyritic. The main rock-forming minerals of host rocks are plagioclase (57–60%), quartz (25–30%), and K-feldspar (6–13%), whereas the main rock-forming minerals of enclaves are plagioclase (65–83%), amphibole (3–20%), and biotite (5–25%). Zircon U-Pb dating results show that the weighted-mean 206Pb/238U ages of the granodiorite host rock and the diorite enclave are 168.1 ± 1.6 Ma and 181.0 ± 1.0 Ma, respectively. The SiO2 contents of the host rocks and enclaves are 61.95–64.86% and 51.12–59.32%, respectively. Their K2O/Na2O ratios are 0.51–1.24 and 0.41–1.02; aluminum saturation index A/CNK [Al2O3/(CaO + Na2O + K2O) molar ratio] are between 0.80–1.14 and 0.70–0.98 and A/NK [Al2O3/(Na2O + K2O) molar ratio] are 1.48–1.97 and 1.47–2.11, indicating a medium-high-K calc-alkaline series and a metaluminous series. The chondrite-normalized rare earth element (REE) patterns of both host rock and enclave samples show a right-dip model, but the Eu ratios of the host rock samples show weak negative anomalies, whereas the Eu ratios of the enclave samples show distinctive negative anomalies. The δEu [δEu = EuN/sqrt(SmN × GdN)] averages of both host rock and enclave samples are 0.75 and 0.63, respectively. The primary mantle normalized trace element patterns shows the enrichment of Rb, Th, U, La, Zr, Hf and Li and the depletion of Nb and Sm in the granodiorite host rocks, whereas enriched Rb, U, La, Pr, Nd, Zr, Hf, and Li and depleting Ba, Nb, Sr, Sm, and Eu are presented in the diorite enclaves. The REE, trace element patterns and the other geochemical indices indicate both granodiorite and diorite were derived from partial melting of pre-existent basaltic materials with a minor contribution of mantle materials. Host rocks and enclaves were formed in the same subduction-related paleotectonic environment, but in different stages of magma evolution. The subduction triggered the delamination of the lithosphere, causing upwelling of the asthenosphere and partial melting of the crust, forming the magmatic precursors of both kinds of rocks.

Impact test of a centrifugal pump used in nuclear power plant under aircraft crash scenario

Huang, Tao,Chen, Mengmeng,Li, Zhongcheng,Dong, Zhanfa,Zhang, Tiejian,Zhou, Zhiguang Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6

Resisting an accidental impact of large commercial aircrafts is an important aspect of advanced nuclear power plant (NPP) design. Especially after the 9·11 event, some regulations were enacted, which required the design of NPPs should consider the accidental impact of large commercial aircrafts. Normal working of equipment is important for stopping reactor under an impact when an NPP is in operation. However, there is a lack of reliable analysis and research on the impact test of nuclear prototype equipment. Therefore, in order to study the response of the equipment under high acceleration impact, a centrifugal pump is selected as the research object to perform the impact test. A horizontal half-sinusoidal pulse wave was applied to the working pump. The test results show that the horizontal response of the motor and flange is greater compared to other parts, as well as the vertical response of the coupling. The stress response of the pump body support and motor support is high, hence these parts should be considered in the design of the pump. Finally, combined with the damage and stress evaluation results of the pump under different amplitudes, the ultimate impact acceleration that the pump can withstand is given.

The differentiation of rat-induced pluripotent stem cells into alveolar type II epithelial cells with a three-step induction protocol

Bei Wu,Chen Wang,Feilong Hei,Cun Long,Mengmeng Chen,Shengnan Yang,Jie Yu,Zhihai Ju 한국통합생물학회 2015 Animal cells and systems Vol.19 No.1

Induced pluripotent stem (iPS) cells derive from autologous somatic cells, the application prospect of iPS cells forregenerative medicine and tissue engineering is better than embryonic stem cells (ESCs) to some extent. Alveolar type II(AT II) epithelial cells play key role in the injured lung tissue regeneration and function recovery. The differentiation of iPScells into AT II cells could provide available source for injured lung treatment. In this study, rat iPS (riPS) cells wereresuscitated and proliferated for 14 days before differentiation. A modified three-step induction protocol similar to thereported ESCs inducing procedure was used in this study for the differentiation groups. Routine cell culture was done to theriPS cell control group (riPS-con). At stage 3, cells of day 7 (Diff. 7) and day 14 (Diff. 14) were collected for the real-timepolymerase chain reaction tests for gene expressions of Oct4, Nanog, SPA, SPB, SPC, SPD, and CC10. Immunofluorescencestaining of SPC and SSEA-1 was conducted. At the end of the differentiation, cell morphology becameoutstretched and epithelium-like. Cells of the Diff. 14 group positively expressed SPC and negatively expressed SSEA-1,which is contrary to the riPS-con group. In the Diff. 7 and the Diff. 14 groups, the expression of Oct4, Nanog, and SPBdecreased (P < 0.05), whereas the expression of SPA, SPC, SPD (P < 0.05), and CC10 (P > 0.05) increased. This studyindicated that riPS cells can successfully differentiate into AT II epithelial cells with the three-step induction protocol andmay be further applied to implanting in decellularized rat lung scaffolds and building a bio-artificial lung.

Distributed Fuzzy Resilient Tracking for Nonlinear MASs Under DoS Attacks

Shu-Huan Gao,Mengmeng Chen,Chao Deng 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.10

In this paper, the distributed fuzzy resilient tracking problem for a class of second-order nonlinear multiagent systems (MASs) under denial-of-service (DoS) attacks is addressed. Compared with the existing distributed fuzzy tracking results, a more general class of second-order MASs with DoS attacks under combined output observable situation are considered in this paper. Under DoS attacks, the second-order derivative of the traditional distributed observer does not exist, while this signal is necessary to solve the distributed fuzzy tracking problem for second-order MASs when using the backstepping method. To solve the problem, a hierarchical control method that consists of a cooperative resilient observer and a distributed controller is proposed. Specifically, a new distributed resilient observer state with a second-order derivative and also the function of defending network attacks is designed based on a combined output observable condition. By using the backstepping technique, decentralized fuzzy adaptive resilient controllers are designed to achieve distributed tracking under DoS attacks. It is shown that the distributed fuzzy resilient tracking problem can be solved under our designed method. Finally, second-order nonlinear MASs are provided to verify the effectiveness of our method.

Patterning-Induced Ferromagnetism of Fe₃GeTe₂ van der Waals Materials beyond Room Temperature

Li, Qian,Yang, Mengmeng,Gong, Cheng,Chopdekar, Rajesh V.,N’Diaye, Alpha T.,Turner, John,Chen, Gong,Scholl, Andreas,Shafer, Padraic,Arenholz, Elke,Schmid, Andreas K.,Wang, Sheng,Liu, Kai,Gao, Nan,Admas American Chemical Society 2018 NANO LETTERS Vol.18 No.9

<P>Magnetic van der Waals (vdW) materials have emerged as promising candidates for spintronics applications, especially after the recent discovery of intrinsic ferromagnetism in monolayer vdW materials. There has been a critical need for tunable ferromagnetic vdW materials beyond room temperature. Here, we report a real-space imaging study of itinerant ferromagnet Fe<SUB>3</SUB>GeTe<SUB>2</SUB> and the enhancement of its Curie temperature well above ambient temperature. We find that the magnetic long-range order in Fe<SUB>3</SUB>GeTe<SUB>2</SUB> is characterized by an unconventional out-of-plane stripe-domain phase. In Fe<SUB>3</SUB>GeTe<SUB>2</SUB> microstructures patterned by a focused ion beam, the out-of-plane stripe domain phase undergoes a surprising transition at 230 K to an in-plane vortex phase that persists beyond room temperature. The discovery of tunable ferromagnetism in Fe<SUB>3</SUB>GeTe<SUB>2</SUB> materials opens up vast opportunities for utilizing vdW magnets in room-temperature spintronics devices.</P> [FIG OMISSION]</BR>

Investigation on characteristics of pressure fluctuation in a centrifugal pump with clearance flow

Lulu Zheng,Xiaoping Chen,Wei Zhang,Zu-chao Zhu,Jinglei Qu,Mengmeng Wang,Xiaojie Ma,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Clearance flow has great impact on pressure fluctuation of centrifugal pumps. Numerical calculations are performed to study the pressure fluctuation characteristics of centrifugal pump with wear ring clearance, especially in the regions of interaction between main flow and clearance flow (IMC) and clearance. The accuracy of numerical calculations is illustrated by comparing the experiments of performance and pressure fluctuation. Results show that, in clearance region the pressure fluctuation is still governed by blade passing frequency (f BPF ). Its amplitude of dominate frequency of pressure fluctuation becomes larger as the probe approaches the impeller exit. In IMC region, the pressure fluctuation at impeller outlet is dominated by f BPF . However, the dominate frequency at the entrance of impeller is less than f BPF . In addition, as the flow rate increased, the amplitude of dominate frequency of pressure fluctuation increases at impeller entrance, whereas an inverse trend is observed at wear ring clearance region.