Construction and effect of intramolecular hydrogen bond on solvent resistance of polymeric membranes and their application in impermeable membranes

Xiaoyun Li,Zhen Wang,Xin Jing,Xudong Li,Junwei Wang,Mao-qing Kang,Yuhua Zhao,Qifeng Li 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-

Hydrogen bonds, which can be divided into many types along with the deepening of research, exist inmany compounds and have certain impact on properties of substances. In this work, effect of intramolecularhydrogen bond on solvent resistance of polymeric membranes was studied from two aspects. On theone hand, the existence of intramolecular hydrogen bond on solvent resistance of polymeric membraneswas studied by constructing and shielding special hydroxyl groups in typical polymer polyurethane. Onthe other hand, content of intramolecular hydrogen bond on solvent resistance was investigated by buildingdifferent ratios of inter- and intra-molecular hydrogen bonds in polyvinyl alcohols. The structures,solvent resistance and hydrogen bonding interactions were systematically investigated by FT-IR, XRD,Ds and performances before and after immersed in solvents. Permeabilities of the membranes for practicalapplication were also characterized. The results showed that distinct type and ratio of hydrogenbonds played different role on solvent resistance. A good agreement between the swelling performancesand content of intramolecular hydrogen bond proved the positive effect of intramolecular hydrogen bondon solvent durability of polymeric membranes. In addition, polyurethane membranes exhibited goodimpermeability to water vapor, oxygen and chloride ions which showed potential application in manyfields.

Flexible camera series network for deformation measurement of large scale structures

Qifeng Yu,Banglei Guan,Yang Shang,Xiaolin Liu,Zhang Li 국제구조공학회 2019 Smart Structures and Systems, An International Jou Vol.24 No.5

Deformation measurement of large scale structures, such as the ground beds of high-rise buildings, tunnels, bridge, and railways, are important for insuring service quality and safety. The pose-relay videometrics method and displacement-relay videometrics method have already presented to measure the pose of non-intervisible objects and vertical subsidence of unstable areas, respectively. Both methods combine the cameras and cooperative markers to form the camera series networks. Based on these two networks, we propose two novel videometrics methods with closed-loop camera series network for deformation measurement of large scale structures. The closed-loop camera series network offers “closed-loop constraints” for the camera series network: the deformation of the reference points observed by different measurement stations is identical. The closed-loop constraints improve the measurement accuracy using camera series network. Furthermore, multiple closed-loops and the flexible combination of camera series network are introduced to facilitate more complex deformation measurement tasks. Simulated results show that the closed-loop constraints can enhance the measurement accuracy of camera series network effectively.

Variations in the Sensible Heating of Tibetan Plateau and Related Effects on Atmospheric Circulation Over South Asia

Li Liu,Wenjiang Zhang,Qifeng Lu,Genxu Wang 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.3

Thermal effects of the Tibetan Plateau (TP) play an important role in the atmospheric circulation over south Asia, which may have complex implications on the development of regional climate. In the study, we utilized 86 station-based observations (1980– 2018) to investigate the variations in sensible heating on the plateau surface and their possible impacts on south Asian atmospheric circulation in terms of the Indian Subtropical High. With 10-year records expansion relative to prior studies, our results suggested the significant increasing trend in regional sensible heat (SH) flux from 2001 to 2018 (0.259 W m− 2 a− 1, p<0.05) contrary to the earlier pronounced decrease (-0.172Wm− 2 a− 1, p < 0.05; 1980–2000) especially in cold season. Most (33) of the 35 stations that decreased in cold-season SH flux before the shift year 2000, did not remain such temporal trend after 2000. Totally, there were respectively 44 and 5 stations showing increasing and decreasing trends in cold-season SH flux from 2001 to 2018, in contrast to the corresponding 6 and 35 stations during the period of 1980–2000. Our results also indicated that the later stronger sensible heating from the TP exhibited statistically close correlation (-0.574~-0.445 o/(Wm− 2), p < 0.05) with the Indian Subtropical High, which tended to move southerly and shrink. Our study highlighted the possible weakening effect of the TP’s intensifying sensible heating on the atmospheric circulation over south Asia due to climate warming.

The Impact of Trade Facilitation of RCEP Countries on China's Agricultural Exports: Empirical Analysis Based on 13 Countries

Qifeng Zhang,Li Cai,Xi Chen,Jin-Long Zhang 한국무역학회 2023 Journal of Korea trade Vol.27 No.3

Purpose – Using trade data from 2008 to 2019, this study analyzes the impact of trade facilitation on China's agricultural exports under the RCEP framework using a gravity model based on the level of trade facilitation in 13 RCEP countries. Design/methodology – This study constructs a complete set of trade facilitation index systems, comprehensively measures the trade facilitation level of RCEP member countries, and uses a gravity model to verify the critical role of trade facilitation level in enhancing the trade volumes of RCEP member countries. Findings – We found that trade facilitation has a significant impact on China's agricultural exports as a whole. The effect of each primary indicator varies in magnitude, with finance and e-commerce (F) having the most significant impact, followed by customs efficiency (C) and infrastructure development (1); the institutional environment has no significant effect. Originality/value – This study analyzes the impact of trade facilitation on China's agricultural exports from the perspective of exports, and uses the latest data to study the degree of the impact of trade facilitation in importing countries. Measures to jointly enhance trade facilitation among member countries under the RCEP framework are proposed.

Smooth projective horospherical varieties with nef tangent bundles

Indiana University Mathematics Journal 2017 Indiana University mathematics journal Vol.66 No.6

Deformation of the product of complex Fano manifolds

Elsevier 2018 Academie des Sciences. Comptes Rendus. Mathematiqu Vol.356 No.5

<P><B>Abstract</B></P> <P>Let X be a connected family of complex Fano manifolds. We show that if some fiber is the product of two manifolds of lower dimensions, then so is every fiber. Combining with previous work of Hwang and Mok, this implies immediately that if a fiber is a (possibly reducible) Hermitian symmetric space of compact type, then all fibers are isomorphic to the same variety.</P>

VGLL4 interacts with STAT3 to function as a tumor suppressor in triple-negative breast cancer

Hongming Song,Qifeng Luo,Xiaochong Deng,Changle Ji,Dengfeng Li,Amik Munankarmy,Wei Jian,Junyong Zhao,Lin Fang 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Triple-negative breast cancer (TNBC) is an aggressive malignancy with a poor prognosis, and there are no effective molecular-targeted drugs for TNBC patients in clinical practice. The JAK-STAT pathway is implicated in tumorigenesis and the progression of various cancers. In this study, the results demonstrated that VGLL4 is expressed at low levels in both TNBC specimens and cell lines and that VGLL4 expression is negatively correlated with Ki67 expression and tumor size in TNBC patients. VGLL4 knockdown can promote the growth of TNBC cells, while VGLL4 overexpression significantly suppresses the growth of TNBC cells in vitro. More importantly, VGLL4 significantly inhibits tumor progression in a nude mouse model. In addition, VGLL4 is a direct target of miR-454, and the upregulation of miR-454 decreases VGLL4 expression and promotes the cell growth of TNBC cells. Furthermore, we also demonstrated that VGLL4 interacts with STAT3, the core component of the JAK-STAT pathway, leading to the inactivation of STAT3 and the inhibition of STAT3 downstream transcription. Collectively, these findings indicate that VGLL4 expression is negatively associated with poor prognosis in TNBC patients. High expression of miR-454 may be one of the causes of the downregulation of VGLL4 in TNBC, and VGLL4 acts as a tumor suppressor in TNBC by interacting with STAT3 and subsequently suppresses the STAT3 signaling axis, providing potential biomarkers and therapeutic approaches for this fatal disease.

Interaction between Brucella melitensis 16M and small ubiquitin-related modifier 1 and E2 conjugating enzyme 9 in mouse RAW264.7 macrophages

Jihai Yi,Yueli Wang,Qifeng Li,Huan Zhang,Zhiran Shao,XiaoYu Deng,Jinke He,Chencheng Xiao,Zhen Wang,Yong Wang,Chuangfu Chen 대한수의학회 2019 Journal of Veterinary Science Vol.20 No.5

Brucella is an intracellular pathogen that invades a host and settles in its immune cells; however, the mechanism of its intracellular survival is unclear. Modification of small ubiquitin-related modifier (SUMO) occurs in many cellular activities. E2 conjugating enzyme 9 (Ubc9) is the only reported ubiquitin-conjugating enzyme that links the SUMO molecule with a target protein. Brucella's intracellular survival mechanism has not been studied with respect to SUMO-related proteins and Ubc9. Therefore, to investigate the relationship between Brucella melitensis 16M and SUMO, we constructed plasmids and cells lines suitable for overexpression and knockdown of SUMO1 and Ubc9 genes. Brucella 16M activated SUMO1/Ubc9 expression in a time-dependent manner, and Brucella 16M intracellular survival was inhibited by SUMO1/Ubc9 overexpression and promoted by SUMO1/Ubc9 depletion. In macrophages, Brucella 16M-dependent apoptosis and immune factors were induced by SUMO1/Ubc9 overexpression and restricted by SUMO1/Ubc9 depletion. We noted no effect on the expressions of SUMO1 and Ubc9 in B. melitensis 16M lipopolysaccharide-prestimulated mouse RAW264.7 macrophages. Additionally, intracellular survival of the 16MΔVirB2 mutant was lower than that of Brucella 16M (p < 0.05). VirB2 can affect expression levels of Ubc9, thereby increasing intracellular survival of Brucella in macrophages at the late stage of infection. Collectively, our results demonstrate that B. melitensis 16M may use the VirB IV secretion system of Brucella to interact with SUMO-related proteins during infection of host cells, which interferes with SUMO function and promotes pathogen survival in host cells.

A systematic method from influence line identification to damage detection: Application to RC bridges

Zhi-Wei Chen,Weibiao Yang,Jun LI,Qifeng Cheng,Qinlin Cai 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.5

Ordinary reinforced concrete (RC) and prestressed concrete bridges are two popular and typical types of short- and medium-span bridges that accounts for the vast majority of all existing bridges. The cost of maintaining, repairing or replacing degraded existing RC bridges is immense. Detecting the abnormality of RC bridges at an early stage and taking the protective measures in advance are effective ways to improve maintenance practices and reduce the maintenance cost. This study proposes a systematic method from influence line (IL) identification to damage detection with applications to RC bridges. An IL identification method which integrates the cubic B-spline function with Tikhonov regularization is first proposed based on the vehicle information and the corresponding moving vehicle induced bridge response time history. Subsequently, IL change is defined as a damage index for bridge damage detection, and information fusion technique that synthesizes ILs of multiple locations/sensors is used to improve the efficiency and accuracy of damage localization. Finally, the feasibility of the proposed systematic method is verified through experimental tests on a three-span continuous RC beam. The comparison suggests that the identified ILs can well match with the baseline ILs, and it demonstrates that the proposed IL identification method has a high accuracy and a great potential in engineering applications. Results in this case indicate that deflection ILs are superior than strain ILs for damage detection of RC beams, and the performance of damage localization can be significantly improved with the information fusion of multiple ILs.

Influence of stator vane number on performance of the axial-flow pump

Can Kang,Xiaojie Yu,Weifeng Gong,Changjiang Li,Qifeng Huang 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

The interplay of impeller and stator is investigated for an axial-flow pump. Three stator vane numbers of 5, 7 and 9 are devised tomatch the same impeller. The renormalization group k-ε turbulence model is used to simulate three-dimensional flows in three pumpswith different vane numbers. Axial velocity distributions at impeller outlet and stator outlet are comparatively analyzed. Experimentsassess operation performance of the three pumps. Vibration parameters and static pressure fluctuations are measured as well. It is indicatedthat the influence of vane number on both pump head and pump efficiency is insignificant. Large stator vane number contributes tothe improvement of the uniformity of axial velocity distribution at impeller outlet. At stator outlet, similar tendency is revealed. Severevibration occurs near the outlet bend of the pump, as is particularly remarkable at vane number of 9. For the three cases, blade passingfrequency and its harmonics are predominant in the frequency spectra of pressure fluctuations. As flow rate increases from 0.8Q to 1.0Q,high-frequency pressure fluctuations are suppressed considerably at vane number of 9, while the other two cases also manifest a declinein overall pressure fluctuation amplitude. The 7-vane case is the most preferable one among the three cases in terms of both pump performanceand pressure fluctuation between the impeller and the stator.