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Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

ZHANG Xiujuan, XU Yuanze, YI Xiaosu

《化学科学与工程前沿（英文）》 2008年 第2卷 第3期   页码 276-285 doi: 10.1007/s11705-008-0057-5

摘要： The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature dependency of the phase separation time and its potential application in the cure time-temperature processing window. We found that the phase separation time/temperature relationship follows the simple Arrhenius equation. The cure-induced phase separation activation energy (ps) generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time. We also found that (ps) is insensitive to TP content, TP molecular weight and curing rate, but it changes with the cure reaction kinetics and the chemical environment of the systems. With the established phase separation time-temperature dependence relation, we can easily establish the whole cure time-temperature transformation (TTT) diagram with morphology information which is a useful map for the TP/TS composites processing industry.

关键词： separation time-temperature     temperature dependency     cure-induced     separation activation     temperature    

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Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 330-339 doi: 10.1007/s11705-020-1929-6

摘要： This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand (SCOD) systems previously based on aliphatic bismaleimides. These SCOD systems are based on Diels-Alder (DA)/retro-DA reactions. The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented. These maleimides have been protected using DA reaction and characterized by H NMR analysis to determine protection rate and diastereomer ratios. The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied. Kinetic analysis was monitored by H NMR and compared to model study. Finally, both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared. The glass transition temperature values ranged from –20 °C to 14 °C and very good thermal stabilities were observed (up to 300 °C).

关键词： thiol-ene polymerization     self-curing on demand     thia-michael addition     Diels-Alder     maleimide    

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未来装备医工程思维

高金吉

《中国工程科学》 2003年 第5卷 第12期   页码 30-35

摘要：

按照耗散结构理论，人类与其所创造的装备在本质上是有共性的，在与疾病和与故障的斗争方面也有很多相同或相近之处。在系统论的指导下，将医学科学理论和方法用于装备的故障诊断、预测和防治，有可能逐步形成用工程手段来防治故障的专门用于装备的“医学”——“装备医工程”（PME， plant medicine engineering）；讨论了疾病和故障成因及其诊断、病因和故障机理的深层规律、治愈和自愈、治标和治本等共性问题，并就汲取中医的黑箱法和西医白箱法的精髓，创建医工程的水晶箱法进行了探讨；应用上述理论，对当前设备诊断技术研究的若干误区进行了分析。

关键词： 装备医工程     疾病     故障     防治    

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Current advances in the elimination of hepatitis B in China by 2030

null

《医学前沿（英文）》 2017年 第11卷 第4期   页码 490-501 doi: 10.1007/s11684-017-0598-4

摘要：

With its 78 million chronic carriers, hepatitis B virus (HBV) infection is still one of the leading public health challenges in China. Over the last two decades, China has made great progress on the prevention of HBV transmission through national vaccination programs. Zero transmission from mother to infant has been proposed as the current goal. Available anti-HBV therapy is efficacious in suppressing HBV replication; however, it fails to completely cure patients with chronic hepatitis B and even requires lifelong treatment. To reduce the costs and improve the efficacy, several trials have been recently conducted in China to optimize the current anti-HBV managements. Novel biomarkers were identified to predict treatment outcomes, and new promising treatment strategies were developed. Reports also indicate that coinfections of HBV with other hepatotropic viruses and human immunodeficiency virus are common in China and cause severe liver diseases, which should be recognized early and treated properly. Work is still needed to eliminate hepatitis B in China by 2030.

关键词： HBV     CHB     biomarker     functional cure     coinfection    

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Treatment of gingival hyperplasia induced by cyclosporine A

MA Jingzhi, LI Ming, CAO Yingguang

《医学前沿（英文）》 2008年 第2卷 第3期   页码 290-294 doi: 10.1007/s11684-008-0055-5

摘要： The clinical therapy for cyclosporine A (CsA)-induced gingival hyperplasia (GH) and the pathological changes in hyperplastic gingival tissues were investigated. Nine cases of CsA-induced GH after renal transplantation were subjected to periodontal non-surgical treatment and surgical treatment and were followed up. Gingival index (GI), dental plaque index (PLI) and GH degree (GHD) at different time points were measured. Under light and electron microscopy, the pathological changes in hyperplastic gingival tissues were observed. The CsA concentrations in gingival tissues and blood were determined by using fluorescence polarization immunoassay with TDFL monoclonal antibody. The results showed that GI, PLI and GHD in patients with GH declined after periodontal treatment. Two patients suffered from different degrees of GH during the 6 months to 54 months post-transplantation. Under transmission electron microscopy, fibroblasts in the hyperplastic gingival tissues were enlarged, cytoplasmic rough endoplasmic reticula were abundant and expanded slightly, and a few fibroblasts with early apoptotic changes were seen. The concentrations of CsA in hyperplastic gingival tissues were from 351.00 to 1345.47 ng/mL, which were significantly higher than in the blood of the same patients taken at the same time points. It was concluded that GI and PLI declined after periodontal treatment in combination with surgical treatment in patients taking CsA for a long time, but in some patients, GH recurred. The fact that the concentration of CsA in hyperplastic gingival tissues is higher than in blood awaits further studies.

关键词： post-transplantation     Gingival     cytoplasmic     CsA-induced     further    

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Influence of fluid-structure interaction on vortex induced vibration and lock-in phenomena in long span

Nazim Abdul NARIMAN

《结构与土木工程前沿（英文）》 2016年 第10卷 第4期   页码 363-384 doi: 10.1007/s11709-016-0353-y

摘要： In this paper, deck models of a cable stayed bridge are generated in ABAQUS-finite element program once using only CFD model (one-way fluid-structure interaction) and another by using both the CFD model and the CSD model together (two-way fluid-structure interaction) in a co-simulation. Shedding frequencies for the associated wind velocities in the lock-in region are calculated in both approaches. The results are validated with Simiu and Scanlan results. The lift and drag coefficients are determined for the two approaches and the latter results are validated with the flat plate theory results by Munson and coauthors. A decrease in the critical wind velocity and the shedding frequencies considering two-way approach was determined compared to those obtained in the one-way approach. The results of the lift and drag forces in the two-way approach showed appreciable decrease in their values. It was concluded that the two-way approach predicts earlier vortex induced vibration for lower critical wind velocities and lock-in phenomena will appear at lower natural frequencies of the long span bridges. This helps the designers to efficiently plan and consider for the design and safety of the long span bridge against this type of vibration.

关键词： vortex-induced vibration     fluid-structure interaction     Strouhal number     lock-in     kinetic energy    

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Formation of microporous polymeric membranes via thermally induced phase separation: A review

Min Liu,Shenghui Liu,Zhenliang Xu,Yongming Wei,Hu Yang

《化学科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 57-75 doi: 10.1007/s11705-016-1561-7

摘要： A review of recent research related to microporous polymeric membranes formed via thermally induced phase separation (TIPS) and the morphologies of these membranes is presented. A summary of polymers and suitable diluents that can be used to prepare these microporous membranes via TIPS are summarized. The effects of different kinds of polymer materials, diluent types, cooling conditions, extractants and additive agents on the morphology and performance of TIPS membranes are also discussed. Finally new developments in TIPS technology are summarized.

关键词： polymer     microporous membrane     thermally induced phase separation    

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An overview of vortex-induced vibration (VIV) of bridge decks

Teng WU, Ahsan KAREEM

《结构与土木工程前沿（英文）》 2012年 第6卷 第4期   页码 335-347 doi: 10.1007/s11709-012-0179-1

摘要： A brief overview of vortex-induced vibration (VIV) of circular cylinders is first given as most of VIV studies have been focused on this particular bluff cross-section. A critical literature review of VIV of bridge decks that highlights physical mechanisms central to VIV from a renewed perspective is provided. The discussion focuses on VIV of bridge decks from wind-tunnel experiments, full-scale observations, semi-empirical models and computational fluids dynamics (CFD) perspectives. Finally, a recently developed reduced order model (ROM) based on truncated Volterra series is introduced to model VIV of long-span bridges. This model captures successfully salient features of VIV at “lock-in” and unlike most phenomenological models offers physical significance of the model kernels.

关键词： vortex-induced vibration (VIV)     Volterra series     bridge    

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Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone

《化学科学与工程前沿（英文）》 2023年 第17卷 第12期   页码 2061-2073 doi: 10.1007/s11705-023-2366-0

摘要： Herein, three novel tetraphenylethylene hydrazone chemosensors TC12, SC16, and TC16 are prepared for the selective detection of F−. Two NH and one C=N units are incorporated into the sensors for better colorimetric responses, whereas the tetraphenyl unit is in charge of the aggregation-induced emission effect. Among them, compounds SC16 and TC16 form stable gels with some organic solvents. All the tetrahydrofuran/H2O solutions of the three compounds exhibit aggregation-induced emission effect, whereby the fluorescence emission increases by varying degrees with the volume of poor solvent water. Moreover, good aggregation-induced emission effects are observed in the self-assembly of SC16 and TC16. As a sample chemosensor, TC12 in tetrahydrofuran responds to F− selectively with high sensitivity, with the colorimetric and fluorometric detection limits of 8.25 × 10−7 mol·L–1 and 2.69 × 10−7 mol·L–1, respectively. The reversible gel-sol-gel phase transition and color changes indicate that both SC16-dimethyl sulfoxide and TC16-ethyl acetate gels specifically respond to F– with good sensitivity. The detection results are well supported by ultraviolet-visible spectroscopy, fluorescent spectroscopy, and 1H nuclear magnetic resonance. More importantly, the driving forces of gelation are visually clarified through the single crystal X-ray analysis of compound TOMe.

关键词： organogelator     tetraphenylvinyldrazone     single crystal     aggregation-induced emission effect     ion sensing    

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Cellular changes in bronchoalveolar lavage fluid in hyperoxia-induced lung injury

HE Xinbiao, ZHAO Wei

《医学前沿（英文）》 2008年 第2卷 第4期   页码 370-373 doi: 10.1007/s11684-008-0071-5

摘要： It is well known that high concentration oxygen exposure is a model of acute lung injury (ALI). However, controversy exists over the mechanism. This study was designed to clarify the cellular characteristics in bronchoalveolar lavage fluid (BALF) and body weight loss of rats exposed to oxygen(> 90%). Young male Wistar rats, aged 6 weeks, were divided into three groups: (1) room air group (exposed to room air, = 22); (2) hyperoxia < 48 h group (exposed to over 90% oxygen for less than 48 h, = 18); (3) hyperoxia 66–72 h group (exposed to over 90% oxygen for 66–72 h group, = 7). Compared to the room air group, the total cell counts in the hyperoxia 66–72 h group decreased, whereas the neutrophils increased significantly. The body weights of the rats exposed to room air continued to increase. However, the body weights of oxygen-exposed rats increased slightly on the first day and weight loss was seen from the second day. All rats were noted to have bilateral pleural effusion in the hyperoxia 66–72 h group. The data suggests that (1) an increase in neutrophil count is an evident feature of hyperoxia-induced lung injury; (2) high concentration oxygen exposure can give rise to anorexia and malnutrition, which may play a role in hyperoxia-induced lung injury. Blocking neutrophil influx into lung tissue in the early phase and improving malnutrition are two effective methods to reduce hyperoxic lung injury.
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Effect of succinic acid deamidation-induced modification on wheat gluten

Lan LIAO, Mouming ZHAO, Haifeng ZHAO, Jiaoyan REN, Chun CUI, Xiao HU,

《化学科学与工程前沿（英文）》 2009年 第3卷 第4期   页码 386-392 doi: 10.1007/s11705-009-0250-1

摘要： The effect of succinic acid deamidation-induced modification on wheat gluten was investigated in the present study. The changes of surface hydrophobicity, functional properties, secondary structure, and sensibility of proteolysis of modified samples were determined. The solubility of deamidated proteins increased in the isoelectric region of untreated wheat gluten. The isoelectric point of succinic acid deamidated wheat gluten was shifted to a basic pH and existed in the broad pH regions. Foaming property and molecular flexibility of wheat gluten were improved after the modification. The hydrolysis degree of the hydrolysates in proteolysis with flavorzyme and pancreatin increased after succinic acid deamidation. Moreover, succinic acid deamidation-induced modification resulted in little change in molecular weight and secondary structure of the protein. Thus, succinic acid could facilitate unfolding protein conformation. In addition, it could improve protein-water interactions, surface properties, and sensibility of the proteolysis of the deamidated wheat gluten.

关键词： pH     isoelectric     conformation     deamidation-induced modification     molecular flexibility    

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Vortex-induced vibration of stay cable under profile velocity using CFD numerical simulation method

Wenli CHEN, Hui LI,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 357-363 doi: 10.1007/s11709-009-0060-z

摘要： Vortex-induced vibration (VIV) of a stay cable subjected to a wind profile is numerically simulated through combining computational fluid dynamics (CFD) code CFX 10.0 and computational structural dynamics (CSD) code ANSYS 10.0. A stay cable with the inclined angle of 30° is used as the numerical model. Under a profile of mean wind speed, unsteady aerodynamic lift coefficients of the cable have been analyzed in both time domain and frequency domain when VIV occurs. The results indicate that the lift coefficient wave response of the stay cable under a wind profile is different from that of an infinitely long cable under a uniform flow in water (i.e., without consideration of profile) obtained by direct numerical simulation. Cable oscillations can severely affect the unsteady aerodynamic frequencies, change flow field distribution near the cable and affect the vortex shedding in the wake.

关键词： stay cable     fluid-structure interaction     numerical simulation     vortex-induced vibration    

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Numerical modeling of current-induced scour around multi-wall foundation using large-eddy simulation

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 546-565 doi: 10.1007/s11709-023-0943-4

摘要： Scouring is one of the primary triggers of failure for bridges across rivers or seas. However, research concerning the scour mechanism of multi-wall foundations (MWFs) remains scarce, hindering the further application of MWFs. In this study, for the first time, the scouring effect caused by unidirectional flow around MWFs was examined numerically using FLOW-3D involving a large-eddy simulation. Initially, the applicability of the scouring model and input parameters was validated using a case study based on published measured data. Subsequently, the scouring effects of four MWFs with different wall arrangements and inflow angles, including the flow field analysis and scour pit and depth, were investigated thoroughly. It was found that the maximum scour depth of MWFs with an inflow angle of 0° was smaller than that of those with an inflow angle of 45°, regardless of the wall arrangement. Meanwhile, changing the inflow angle significantly affects the scour characteristics of MWFs arranged in parallel. In practical engineering, MWFs arranged in parallel are preferred considering the need for scouring resistance. However, a comparative analysis should be performed to consider comprehensively whether to adopt the form of a round wall arrangement when the inflow angle is not 0° or the inflow direction is changeable.

关键词： multi-wall foundation     current-induced scour     bridge foundation     large-eddy simulation     numerical analysis    

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Prediction of characteristic blast-induced vibration frequency during underground excavation by using

Tae Un PAK; Guk Rae JO; Un Chol HAN

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1029-1039 doi: 10.1007/s11709-022-0861-x

摘要： Blast-induced vibration produces a very complex signal, and it is very important to work out environmental problems induced by blasting. In this study, blasting vibration signals were measured during underground excavation in carbonaceous shale by using vibration pickup CB-30 and FFT analyzer AD-3523. Then, wavelet analysis on the measured results was carried out to identify frequency bands reflecting changes of blasting vibration parameters such as vibration velocity and energy in different frequency bands. Frequency characteristics are then discussed in view of blast source distance and charge weight per delay. From analysis of results, it can be found that peak velocity and energy of blasting vibration in frequency band of 62.5–125 Hz were larger than ones in other bands, indicating the similarity to characteristics in the distribution band (31–130 Hz) of main vibration frequency. Most frequency bands were affected by blasting source distance, and the frequency band of 0–62.5 Hz reflected the change of charge weight per delay. By presenting a simplified method to predict main vibration frequency, this research may provide significant reference for future blasting engineering.

关键词： wavelet analysis     blast-induced vibration     frequency characteristics     underground excavation    

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Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 781-792 doi: 10.1007/s11709-021-0733-9

摘要： During the construction of lightweight cellular concrete (LCC), material damage frequently occurs, causing the degradation and deterioration of the mechanical performance, durability, and subgrade quality of LCC. The construction-induced damage can be more significant than those from the service environment of LCC, such as freeze–thaw (F–T) action in cold regions. However, the effect of construction-induced damage on LCC during F–T cycles is often ignored and the deterioration mechanisms are not yet clarified. In this study, we investigated the factors causing damage during construction using a sample preparation method established to simulate the damage in the laboratory setting. We conducted F–T cycle tests and microstructural characterization to study the effect of microstructural damage on the overall strength of LCC with different water contents under F–T actions. We established the relationship between the pore-area ratio and F–T cycle times, pore-area ratio, and strength, as well as the F–T cycle times and strength under different damage forms. The damage evolution is provided with the rationality of the damage equation, verified by comparing the measured and predicted damage variables. This study would serve as a guide for the construction and performance of LCC in cold regions.

关键词： lightweight cellular concrete     construction-induced damage     freeze-thaw action     microstructure     degradation mechanism    

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标题 作者 时间 类型 操作

Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

ZHANG Xiujuan, XU Yuanze, YI Xiaosu

期刊论文

Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

期刊论文

未来装备医工程思维

高金吉

期刊论文

Current advances in the elimination of hepatitis B in China by 2030

null

期刊论文

Treatment of gingival hyperplasia induced by cyclosporine A

MA Jingzhi, LI Ming, CAO Yingguang

期刊论文

Influence of fluid-structure interaction on vortex induced vibration and lock-in phenomena in long span

Nazim Abdul NARIMAN

期刊论文

Formation of microporous polymeric membranes via thermally induced phase separation: A review

Min Liu,Shenghui Liu,Zhenliang Xu,Yongming Wei,Hu Yang

期刊论文

An overview of vortex-induced vibration (VIV) of bridge decks

Teng WU, Ahsan KAREEM

期刊论文

Synthesis and ultraviolet/aggregation-induced emission investigation of novel tetraphenylvinyl hydrazone

期刊论文

Cellular changes in bronchoalveolar lavage fluid in hyperoxia-induced lung injury

HE Xinbiao, ZHAO Wei

期刊论文

Effect of succinic acid deamidation-induced modification on wheat gluten

Lan LIAO, Mouming ZHAO, Haifeng ZHAO, Jiaoyan REN, Chun CUI, Xiao HU,

期刊论文

Vortex-induced vibration of stay cable under profile velocity using CFD numerical simulation method

Wenli CHEN, Hui LI,

期刊论文

Numerical modeling of current-induced scour around multi-wall foundation using large-eddy simulation

期刊论文

Prediction of characteristic blast-induced vibration frequency during underground excavation by using

Tae Un PAK; Guk Rae JO; Un Chol HAN

期刊论文

Influence of construction-induced damage on the degradation of freeze–thawed lightweight cellular concrete

期刊论文