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Solvates and polymorphs of clindamycin phosphate: Structural, thermal stability and moisture stability

Junbo Gong, Dejiang Zhang, Yuanyuan Ran, Keke Zhang, Shichao Du

《化学科学与工程前沿（英文）》 2017年 第11卷 第2期   页码 220-230 doi: 10.1007/s11705-017-1624-4

摘要： Clindamycin phosphate (CP), an antibacterial agent, has been reported to form several solid-state forms. The crystal structures of two CP solvates, a dimethyl sulfoxide (DMSO) solvate and a methanol/water solvate (solvate V), have been determined by single crystal X-ray diffraction. The properties and transformations of these forms were characterized by powder X-ray diffraction, Single-crystal X-ray diffraction, differential scanning calorimetry, thermo gravimetric analysis, hot-stage microscopy, and dynamic vapor sorption. Very different hydrogen bonding networks exist among the host-host and host-solvent molecules in the two crystal structures, resulting in different moisture stabilities. The thermal stabilities of the two solvates upon heating and desolvation were also studied. When the temperature was above the boiling point of methanol, solvate V converted to a polymorphic phase after a one step desolvation process, whereas the desolvation temperature of the DMSO solvate was below the boiling point of DMSO. At the relative humidity above 43%, the DMSO solvate transformed to a hydrate at 25 °C. In contrast, solvate V did not transform at any of the humidities studied.

关键词： clindamycin phosphate     solvate     crystal structure     thermal stability     moisture stability    

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Preparation, with graphene, of novel biomimetic self-healing microcapsules with high thermal stability

《结构与土木工程前沿（英文）》   页码 1188-1198 doi: 10.1007/s11709-023-0027-5

摘要： This paper reports a comparative study of microcapsules with enhanced thermal stability and electrical conductivity inspired by the bionic thermal insulation of birds’ feathers for self-healing aged asphalt. The work is based on an in situ polymerization with composite shell components of graphene and hexamethoxymethylmelamine resin. By using graphene, microcapsules with rough surfaces are achieved, improving the interface between microcapsules and asphalt. In addition, the microcapsules’ initial thermal decomposition temperature is appropriately high, so that the stability of the microcapsule in the asphalt highway system is protected. The proportion of graphene in the microcapsule shell can regulate the microcapsule’s heat resistance because graphene modifies the shell’s structural makeup. Additionally, the microcapsules’ electrical conductivity is relatively high. The self-healing capability of bitumen sharply increases, providing benefit to the effect of microcapsules on the properties of aged asphalt.

关键词： graphene     microcapsule     bitumen     heat insulation     conductivity    

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Coupling evaluation for material removal and thermal control on precision milling machine tools

《机械工程前沿（英文）》 2022年 第17卷 第1期   页码 12-12 doi: 10.1007/s11465-021-0668-9

摘要： Machine tools are one of the most representative machining systems in manufacturing. The energy consumption of machine tools has been a research hotspot and frontier for green low-carbon manufacturing. However, previous research merely regarded the material removal (MR) energy as useful energy consumption and ignored the useful energy consumed by thermal control (TC) for maintaining internal thermal stability and machining accuracy. In pursuit of energy-efficient, high-precision machining, more attention should be paid to the energy consumption of TC and the coupling relationship between MR and TC. Hence, the cutting energy efficiency model considering the coupling relationship is established based on the law of conservation of energy. An index of energy consumption ratio of TC is proposed to characterize its effect on total energy usage. Furthermore, the heat characteristics are analyzed, which can be adopted to represent machining accuracy. Experimental study indicates that TC is the main energy-consuming process of the precision milling machine tool, which overwhelms the energy consumption of MR. The forced cooling mode of TC results in a 7% reduction in cutting energy efficiency. Regression analysis shows that heat dissipation positively contributes 54.1% to machining accuracy, whereas heat generation negatively contributes 45.9%. This paper reveals the coupling effect of MR and TC on energy efficiency and machining accuracy. It can provide a foundation for energy-efficient, high-precision machining of machine tools.

关键词： machine tools     cutting energy efficiency     thermal stability     machining accuracy     coupling evaluation    

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Preparation and performance of novel thermal stable composite nanofiltration membrane

WU Chunrui, ZHANG Shouhai, YANG Fajie, YAN Chun, JIAN Xigao

《化学科学与工程前沿（英文）》 2008年 第2卷 第4期   页码 402-406 doi: 10.1007/s11705-008-0063-7

摘要： The novel thermal stable composite nanofiltration membranes were prepared through the interfacial polymerization of piperazine and trimesoyl chloride on the poly (phthalazinone ether) ultrafiltration substrate. The effects of polymerization and testing conditions on membrane performance were studied. The surface morphologies of the substrate and the composite membranes were observed by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM). The separation properties of membranes for dyes and salts were tested. The composite membranes show good thermal stability. The rejection for NaSO was kept over 96%, while the flux reached 400 L·m·h when it was tested at 1.0 MPa and 80°C. When tested at 1.0 MPa and 60°C, the rejection of the composite membrane for dyes was kept at high level, and the flux reached 180–210 Lm·h, while the rejection for NaCl was lower than 20%.

关键词： electron microscopy     rejection     composite membrane     interfacial polymerization     thermal stability    

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非爆炸且不可还原农用硝酸铵的热稳定性评估

汪旭光,沈立晋

《中国工程科学》 2004年 第6卷 第11期   页码 53-57

摘要：

绍了一种测试含能材料热稳定性的新方法——加速度量热仪，并用此法研究了硝酸铵和非爆炸且不可还原农用硝酸铵的热分解过程，得到了绝热分解温度与压力随时间的变化、自加热速率与分解压力随温度的变化曲线，计算了分解动力学参数表观活化能和指前因子，讨论了放热反应系统的热惰性因子对测试结果的影响，表明非爆炸且不可还原农用硝酸铵具有良好的热稳定性、安全性及其热稳定性的提高是爆炸特性得以消除的原因。

关键词： 农用硝酸铵     非爆炸性     不可还原性     加速度量热仪     热稳定性    

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Rosin side chain type catalyst-free vitrimers with high cross-link density, mechanical strength, and thermalstability

《化学科学与工程前沿（英文）》 2023年 第17卷 第9期   页码 1267-1279 doi: 10.1007/s11705-022-2291-7

摘要： The emergence of vitrimer, a new class of polymer materials can address the problem of recyclability, reprocess ability and recyclability of thermosetting plastics. Rosin, a natural product, is an ideal raw material for the preparation of polymers in a more sustainable way. Nevertheless, due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure, the cross-link density of materials is frequently lowered. In this study, hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids, which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers. It was completely characterized by differential scanning calorimetry test, thermogravimetric analysis, shape memory test and self-healing test. The prepared vitrimers exhibited good self-healing properties, excellent heat resistance (Td = 352 °C) as well as high mechanical properties (tensile strength of 46.75 MPa). The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton. Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy. Moreover, our work expanded the application field of rosin, increased the added value of rosin, and provided a novel method for preparing rosin-based vitrimers with ideal properties.

关键词： vitrimers     rosin     catalyst-free     high mechanical properties     dynamic transesterification reaction    

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Self-sacrificial templating synthesis of flower-like nickel phyllosilicates and its application as high-performance reinforcements in epoxy nanocomposites

《化学科学与工程前沿（英文）》 2022年 第16卷 第4期   页码 484-497 doi: 10.1007/s11705-021-2074-6

摘要： The nanocomposites of flower-like nickel phyllosilicate particles incorporated into epoxy resin were fabricated via an in-situ mixing process. The flower-like nickel phyllosilicate particles were firstly synthesized using a mild self-sacrificial templating method, and the morphology and lamellar structure were examined carefully. Several properties of mechanical, thermal and tribological responses of epoxy nanocomposites were performed. It was demonstrated that adequate flower-like nickel phyllosilicate particles dispersed well in the matrix, and the nanocomposites displayed enhanced tensile strength and elastic modulus but decreased elongation at break as expected. In addition, friction coefficient and wear rate were increased first and then decreased along with the particle content, and showed the lowest values at a mass fraction of 5%. Nevertheless, the incorporated flower-like nickel phyllosilicate particles resulted in the continuously increasing thermal stability of epoxy resin (EP) nanocomposites. This study revealed the giant potential of flower-like particles in preparing high-quality EP nanocomposites.

关键词： nickel phyllosilicate     flow-like structure     mechanical property     thermal stability     tribological performance    

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Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO absorption: Characterizations and DFT analysis

《环境科学与工程前沿（英文）》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1500-9

摘要：

•Addition of hindered amine increased thermal stability and viscosity of TTTM.

关键词： Ternary transition-temperature mixture     FT-IR and thermal stability analysis     Viscosity and correlation study     Eyring’s absolute rate theory     CO2 solubility     Density functional theory (DFT).    

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Evaluation and prediction of slope stability using machine learning approaches

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 821-833 doi: 10.1007/s11709-021-0742-8

摘要： In this paper, the machine learning (ML) model is built for slope stability evaluation and meets the high precision and rapidity requirements in slope engineering. Different ML methods for the factor of safety (FOS) prediction are studied and compared hoping to make the best use of the large variety of existing statistical and ML regression methods collected. The data set of this study includes six characteristics, namely unit weight, cohesion, internal friction angle, slope angle, slope height, and pore water pressure ratio. The whole ML model is primarily divided into data preprocessing, outlier processing, and model evaluation. In the data preprocessing, the duplicated data are first removed, then the outliers are filtered by the LocalOutlierFactor method and finally, the data are standardized. 11 ML methods are evaluated for their ability to learn the FOS based on different input parameter combinations. By analyzing the evaluation indicators R 2, MAE, and MSE of these methods, SVM, GBR, and Bagging are considered to be the best regression methods. The performance and reliability of the nonlinear regression method are slightly better than that of the linear regression method. Also, the SVM-poly method is used to analyze the susceptibility of slope parameters.

关键词： slope stability     factor of safety     regression     machine learning     repeated cross-validation    

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Modified Bishop method for stability analysis of weakly sloped subgrade under centrifuge model test

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 727-741 doi: 10.1007/s11709-021-0730-z

摘要： The sliding forms of weak sloped and horizontal subgrades during the sliding process differ. In addition, the sliding form of weakly sloped subgrades exhibits considerable slippage and asymmetry. The accuracy of traditional slice methods for computing the stability safety factor of weakly sloped subgrades is insufficient for a subgrade design. In this study, a novel modified Bishop method was developed to improve the accuracy of the stability safety factor for different inclination angles. The instability mechanism of the weakly sloped subgrade was considered in the proposed method using the “influential force” and “additional force” concepts. The “additional force” reflected the weight effect of the embankment fill, whereas the “influential force” reflected the effect of the potential energy difference. Numerical simulations and experimental tests were conducted to evaluate the advantages of the proposed modified Bishop method. Compared with the traditional slice method, the error between the proposed method and the exact value is less than 32.3% in calculating the safety factor.

关键词： weakly sloped subgrade     stability analysis     additional force     influential force     modified Bishop method    

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Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

《机械工程前沿（英文）》 2018年 第13卷 第4期   页码 563-570 doi: 10.1007/s11465-018-0487-9

摘要：

The thermal hydraulic (TH) behavior of coo-lant water is a key factor in the structural integrity assessments on reactor pressure vessels (RPVs) of pressurized water reactors (PWRs) under pressurized thermal shock (PTS) events, because the TH behavior may affect the loading conditions in the assessment. From the viewpoint of TH behavior, configuration of plant equipment and their dimensions, and operator action time considerably influence various parameters, such as the temperature and flow rate of coolant water and inner pressure. In this study, to investigate the influence of the operator action time on TH behavior during a PTS event, we developed an analysis model for a typical Japanese PWR plant, including the RPV and the main components of both primary and secondary systems, and performed TH analyses by using a system analysis code called RELAP5. We applied two different operator action times based on the Japanese and the United States (US) rules: Operators may act after 10 min (Japanese rules) and 30 min (the US rules) after the occurrence of PTS events. Based on the results of TH analysis with different operator action times, we also performed structural analyses for evaluating thermal-stress distributions in the RPV during PTS events as loading conditions in the structural integrity assessment. From the analysis results, it was clarified that differences in operator action times significantly affect TH behavior and loading conditions, as the Japanese rule may lead to lower stresses than that under the US rule because an earlier operator action caused lower pressure in the RPV.

关键词： structural integrity     reactor pressure vessel     pressurized thermal shock     thermal hydraulic analysis     pressurized water reactor     weld residual stress    

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Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿（英文）》 2023年 第17卷 第4期   页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要： Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词： tunnel face stability     cutterhead configuration     aperture ratio     pressure gradient     support ratio    

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Assessment indices for uniform and non-uniform thermal environments

ZHANG Yufeng, SUN Shufeng, ZHAO Rongyi

《能源前沿（英文）》 2008年 第2卷 第2期   页码 129-133 doi: 10.1007/s11708-008-0029-y

摘要： Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments. 30 subjects reported their overall thermal sensation, thermal comfort, and thermal acceptability in uniform and non-uniform conditions. The results show that these three assessment indices provide equivalent evaluations in uniform environments. However, overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments. The relationship between the percentage and the mean vote for each index is established.

关键词： thermal sensation     proper assessment     relationship     equivalent     thermal acceptability    

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Liquid metal thermal hydraulics R&D at European scale: achievements and prospects

《能源前沿（英文）》 2021年 第15卷 第4期   页码 842-853 doi: 10.1007/s11708-021-0743-2

摘要： A significant role for a future nuclear carbon-free energy production is attributed to fast reactors, mostly employing a liquid metal as a coolant. This paper summarizes the efforts that have been undertaken in collaborative projects sponsored by the European Commission in the past 20 years in the fields of liquid-metal heat transfer modeling, fuel assembly and core thermal hydraulics, pool and system thermal hydraulics, and establishment of best practice guidelines and verification, validation, and uncertainty quantification (UQ). The achievements in these fields will be presented along with the prospects on topics which will be studied collaboratively in Europe in the years to come. These prospects include further development of heat transfer models for applied computational fluid dynamics (CFD), further analysis of the consequences of fuel assembly blockages on coolant flow and temperature, analysis of the thermal hydraulic effects in deformed fuel assemblies, extended validation of three-dimensional pool thermal hydraulic CFD models, and further development and validation of multi-scale system thermal hydraulic methods.

关键词： liquid metal     thermal hydraulics     Europe    

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Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and

Shuvankar DAS; Debarghya CHAKRABORTY

《结构与土木工程前沿（英文）》 2022年 第16卷 第8期   页码 1040-1055 doi: 10.1007/s11709-022-0841-1

摘要： In the present study, the stability of a vertical rock escarpment is determined by considering the influence of undercut. Lower bound finite element limit analysis in association with Power Cone Programming (PCP) is applied to incorporate the failure of rock mass with the help of the Generalized Hoek-Brown yield criterion. The change in stability due to the presence of undercut is expressed in terms of a non-dimensional stability number (σci/γH). The variations of the magnitude of σci/γH are presented as design charts by considering the different magnitudes of undercut offset (H/vu and wu/vu) from the vertical edge and different magnitudes of Hoek-Brown rock mass strength parameters (Geological Strength Index (GSI), rock parameter (mi,), Disturbance factor (D)). The obtained results indicate that undercut can cause a severe stability problem in rock mass having poor strength. With the help of regression analysis of the computed results, a simplified design equation is proposed for obtaining σci/γH. By performing sensitivity analysis for an undisturbed vertical rock escarpment, we have found that the undercut height ratio (H/vu) is the most sensitive parameter followed by GSI, undercut shape ratio (wu/vu), and mi. The developed design equation as well as design charts can be useful for practicing engineers to determine the stability of the vertical rock escarpment in the presence of undercut. Failure patterns are also presented to understand type of failure and extent of plastic state during collapse.

关键词： undercut     vertical escarpment     stability     Hoek-Brown yield criterion     PCP    

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标题 作者 时间 类型 操作

Solvates and polymorphs of clindamycin phosphate: Structural, thermal stability and moisture stability

Junbo Gong, Dejiang Zhang, Yuanyuan Ran, Keke Zhang, Shichao Du

期刊论文

Preparation, with graphene, of novel biomimetic self-healing microcapsules with high thermal stability

期刊论文

Coupling evaluation for material removal and thermal control on precision milling machine tools

期刊论文

Preparation and performance of novel thermal stable composite nanofiltration membrane

WU Chunrui, ZHANG Shouhai, YANG Fajie, YAN Chun, JIAN Xigao

期刊论文

非爆炸且不可还原农用硝酸铵的热稳定性评估

汪旭光,沈立晋

期刊论文

Rosin side chain type catalyst-free vitrimers with high cross-link density, mechanical strength, and thermalstability

期刊论文

Self-sacrificial templating synthesis of flower-like nickel phyllosilicates and its application as high-performance reinforcements in epoxy nanocomposites

期刊论文

Potassium carbonate-based ternary transition temperature mixture (deep eutectic analogues) for CO absorption: Characterizations and DFT analysis

期刊论文

Evaluation and prediction of slope stability using machine learning approaches

期刊论文

Modified Bishop method for stability analysis of weakly sloped subgrade under centrifuge model test

期刊论文

Influence evaluation of loading conditions during pressurized thermal shock transients based on thermal-hydraulics

Jinya KATSUYAMA, Shumpei UNO, Tadashi WATANABE, Yinsheng LI

期刊论文

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

期刊论文

Assessment indices for uniform and non-uniform thermal environments

ZHANG Yufeng, SUN Shufeng, ZHAO Rongyi

期刊论文

Liquid metal thermal hydraulics R&D at European scale: achievements and prospects

期刊论文

Effect of undercut on the lower bound stability of vertical rock escarpment using finite element and

Shuvankar DAS; Debarghya CHAKRABORTY

期刊论文