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Mechanism of nanoparticle aggregation in gas-liquid microfluidic mixing

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Chinese Chemical Letters 2024年第4期35卷 376-381页

作者： hongxia li Xiyang Wang Du Qiao Jiahao li Weiping Zhu Honglin li Key Laboratory for Precision&Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116023China Shanghai Key Laboratory of New Drug Design School of PharmacyEast China University of Science and TechnologyShanghai 200237China

Using gas-liquid segmented micromixers to prepare nanoparticles that have a homogeneous particle size, controllable shape, and monodispersity advantages. Although nanoparticle aggregation within a microfluid has been shown to be affected by the shear effect, the shear effect triggering conditions in gasliquid two-phase flow is unclear and the aggregation behavior of nanoparticles under the shear effect is difficult to predict, resulting in uncontrollable physical and chemical properties of nanoparticle aggregates. In this study, a numerical simulation of nanoparticle aggregation in gas-liquid two-phase flow under the shear effect is performed using the CFD-DEM method. Then, the effects of total flow rate,gas-liquid two-phase flow ratio, and particle volume fraction on particle aggregation were analyzed to achieve control of particle aggregation shape and size. Meanwhile, the triggering mechanism of the shear effect and the mechanism of the shear effect on the aggregation of nanoparticles were clarified. The results show that increasing the total flow rate or decreasing the gas-liquid two-phase flow rate ratio can induce the shear effect, which reduces the particle aggregation size and makes the morphology tend to be spherical. Moreover, increasing the particle volume fraction, and total flow rate or decreasing the gas-liquid two-phase flow rate ratio also increases the number of particle collisions and induce interparticle adhesion. Hence, particle adhesion and the shear effect compete with each other and together affect particle aggregation.

关键词： Microfluidic Gas-liquid segmented micromixer Nanoparticle aggregation Shear effect Numerical calculation

Microfluidic separation of particles by synergistic effect of geometry-induced hydrodynamics and magnetic field

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Chinese Chemical Letters 2024年第2期35卷 380-385页

作者： Du Qiao hongxia li Weiping Zhu lili Zhu Danyang Zhao Honglin li Key Laboratory for Precision & Non-traditional Machining Technology of Ministry of Education Dalian University of TechnologyDalian 116023China Shanghai Key Laboratory of New Drug Design School of PharmacyEast China University of Science and TechnologyShanghai 200237China lingang Lab Shanghai 200031China

Microfluidic combined with magnetic field have been demonstrated to be the promising solutions for fast and low-damage particles ***,the difficulties in the precise layout of magnets and accurate prediction of particle trajectories lead to under and over separation of target particles.A novel particle separation lab-on-chip(LOC)prototype integrated with microstructures and micropolar arrays is designed and ***,a numerical model for the separation of magnetic particles by the synergistic effect of geometry-induced hydrodynamics and magnetic field is *** effect of geometry and magnetic field layout on particle deflection is systematically analyzed to implement accurate prediction of particle *** is found that the separation efficiency of magnetic particles increased from 50.2%to 91.7%and decreased from 88.6%to 85.7%in the range of depth factors from 15µm to 27µm and width factors from 30µm to 60µm,*** particular,the combined effect of the offset distance of permanent magnets and the distance from the main flow channel exhibits a significant difference from the conventional ***,the developed LOC prototype was generalized for extension to arbitrary *** work provides a new insight and robust method for the microfluidic separation of magnetic particles.

关键词： Microfluidic Particle separation Synergistic effect Hydrodynamics Magnetic field Numerical calculation

Prediction of the thermal conductivity of Mg–Al–La alloys by CALPHAD method

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 129-137页

作者： hongxia li Wenjun Xu Yufei Zhang Shenglan Yang lijun Zhang Bin liu Qun Luo Qian li State Key Laboratory of Advanced Special Steels&Shanghai Key Laboratory of Advanced Ferrometallurgy&School of Materials Science and Engineering Shanghai UniversityShanghai 200444China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China National Key Laboratory of Advanced Casting Technologies Chongqing UniversityChongqing 400044China

Mg-Al alloys have excellent strength and ductility but relatively low thermal conductivity due to Al *** accurate prediction of thermal conductivity is a prerequisite for designing Mg-Al alloys with high thermal ***,databases for predicting temperature-and composition-dependent thermal conductivities must be *** this study,Mg-Al-La alloys with different contents of Al2La,Al3La,and Al11La3phases and solid solubility of Al in the α-Mg phase were *** influence of the second phase(s) and Al solid solubility on thermal conductivity was *** results revealed a second phase transformation from Al_(2)La to Al_(3)La and further to Al_(11)La_(3)with the increasing Al content at a constant La *** degree of the negative effect of the second phase(s) on thermal diffusivity followed the sequence of Al2La>Al3La>Al_(11)La_(3).Compared with the second phase,an increase in the solid solubility of Al in α-Mg remarkably reduced the thermal *** the basis of the experimental data,a database of the reciprocal thermal diffusivity of the Mg-Al-La system was established by calculation of the phase diagram (CALPHAD)*** a standard error of±1.2 W/(m·K),the predicted results were in good agreement with the experimental *** established database can be used to design Mg-Al alloys with high thermal conductivity and provide valuable guidance for expanding their application prospects.

关键词： magnesium alloy thermal conductivity thermodynamic calculations materials computation

From seawater to hydrogen via direct photocatalytic vapor splitting: A review on device design and system integration

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Frontiers in Energy 2024年第3期18卷 291-307页

作者： hongxia li Khaja WAHAB AHMED Mohamed A.ABDELSALAM Michael FOWLER Xiao-Yu WU Technology Innovation Institute Masdar CityAbu Dhabi 9639United Arab Emirates Department of Chemical Engineering University of WaterlooWaterlooON N2L 3G1Canada Department of Mechanical and Nuclear Engineering Khalifa University of Science and TechnologyAbu Dhabi 127788United Arab Emirates Department of Mechanical and Mechatronics Engineering University of WaterlooWaterlooON N2L 3G1Canada

Solar-driven hydrogen production from seawater attracts great interest for its emerging role in decarbonizing global energy consumption. Given the complexity of natural seawater content, photocatalytic vapor splitting offers a low-cost and safe solution, but with a very low solar-to-hydrogen conversion efficiency. With a focus on cutting-edge photothermal–photocatalytic device design and system integration, the recent research advances on vapor splitting from seawater, as well as industrial implementations in the past decades were reviewed. In addition, the design strategies of the key processes were reviewed, including vapor temperature and pressure control during solar thermal vapor generation from seawater, capillary-fed vaporization with salt repellent, and direct photocatalytic vapor splitting for hydrogen production. Moreover, the existing laboratory-scale and industrial-scale systems, and the integration principles and remaining challenges in the future seawater-to-hydrogen technology were discussed.

关键词： seawater hydrogen photocatalytic vapor splitting solar-driven

Effects of desert plant communities on soil enzyme activities and soil organic carbon in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia,China

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Journal of Arid Land 2024年第5期16卷 725-737页

作者： SHEN Aihong SHI Yun MI Wenbao YUE Shaoli SHE Jie ZHANG Fenghong GUO Rui HE Hongyuan WU Tao li hongxia ZHAO Na College of Forestry and Prataculture of Ningxia University Yinchuan 750021China School of Geography and Planning of Ningxia University Yinchuan 750021China Ningxia Hui Autonomous Region Agricultural Comprehensive Development Center Yinchuan 750002China Ningxia Helan Mountain National Nature Reserve Administration Yinchuan 750021China Yinchuan Yinxi Ecological Protection Forest Management Center Yinchuan 750002China

It is of great significance to study the effects of desert plants on soil enzyme activities and soil organic carbon(SOC)for maintaining the stability of the desert *** this study,we studied the responses of soil enzyme activities and SOC fractions(particulate organic carbon(POC)and mineral-associated organic carbon(MAOC))to five typical desert plant communities(Convolvulus tragacanthoides,Ephedra rhytidosperma,Stipa breviflora,Stipa tianschanica ***,and Salsola laricifolia communities)in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia Hui Autonomous Region,*** recorded the plant community information mainly including the plant coverage and herb and shrub species,and obtained the aboveground biomass and plant species diversity through sample surveys in late July *** samples were also collected at depths of 0–10 cm(topsoil)and 10–20 cm(subsoil)to determine the soil physicochemical properties and enzyme *** results showed that the plant coverage and aboveground biomass of *** community were significantly higher than those of ***,***,and *** *** communities(Pline phosphatase(ALP)andβ-1,4-glucosidas(βG)were significantly higher in *** and *** *** communities than in other plant communities(P<0.05).The topsoil had higher POC and MAOC contents than the ***,the content of POC in the topsoil was 18.17%–42.73%higher than that in the *** structural equation model(SEM)indicated that plant species diversity,soil pH,and soil water content(SWC)were the main factors influencing POC and *** soil pH inhibited the formation of POC and promoted the formation of ***,SWC stimulated POC production and hindered MAOC *** study aimed to gain insight into the effects of desert plant c

关键词： proluvial fan desert plant community soil enzyme activity particulate organic carbon mineral-associated organic carbon Helan Mountain

Study on Antitumor Activity of Piperidine Derivatives

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Agricultural Biotechnology 2024年第3期13卷 81-85,89页

作者： Zhenwei NIE hongxia li Weizhen li Hangyu MENG Wei XU School of Biological and Food Engineering Suzhou UniversitySuzhou 234000China

[Objectives]This study was conducted to investigate the effects of piperidine derivatives on the proliferation and apoptosis of tumor cells(Hele).[Methods]The target end product(piperidine derivative)was synthesized through a series of organic *** MTT assay was adopted to detect the effect of piperidine derivative on the proliferation activity of Hele *** ROS fluorescence probe method was used to detect the changes of reactive oxygen *** JC-1 method was applied to detect the changes of MMP in Hele *** cytometry was adopted to detect the apoptosis of Hele cells.[Results]The cell survival rates were 70.84%,65.46%and 54.48%when the drug concentration was 100,110 and 120μmol/L,*** the drug concentration increased to 120μmol/L,the cell survival rate decreased by nearly *** fluorescence intensity of active oxygen in the control group was 1,and when the drug concentrations were 100,110 and 120μmol/L,the fluorescence intensity of active oxygen was,respectively,1.315,1.478 and 1.677,which were higher than that in the control *** red/green fluorescence intensity of the MMP control group was 1.819,and that of drug groups was,respectively,1.643,1.164 and 0.665,which were lower than that of the control *** apoptosis rates were 10.79%,22.91%and 38.54%at the drug concentrations of 100,110 and 120μmol/L,respectively,showing a concentration dependent *** results showed that the piperidine derivative could inhibit the proliferation of Hele cells and induce apoptosis,which was positively correlated with the concentration.[Conclusions]This study provides theoretical basis and reference for the anti-tumor research of piperidine.

关键词： Piperidine derivative Hele cell Anti-cancer activity

Development of an Integrated Disposable Device for SARSCoV-2 Nucleic Acid Extraction and Detection

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Biomedical and Environmental Sciences 2024年第6期37卷 639-646页

作者： Jing Ma Yanzhe Hao Meiling Hou Xiaoshan Zhang Jingduan liu Haodi Meng Jiangbo Chang Xuejun Ma Jihua liu Qingjie Ying Xianhua Wang hongxia li Yuxi Cao Xiaoguang Zhang National Key Laboratory of Intelligent Tracking and Forecasting for Infectious Diseases National Institute for Viral Disease Control and PreventionChinese Center for Disease Control and PreventionBeijing 102206China Beijing Runbio Biotechnology Development Co. LtdBeijing 100106China Beijing Beta Technology Co. LtdBeijing 101318China Jiangsu Qitian Gene Biotechnology Co. LtdWuxi 214135JiangsuChina

Objective To develop a highly sensitive and rapid nucleic acid detection method for the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Methods We designed,developed,and manufactured an integrated disposable device for SARS-CoV-2 nucleic acid extraction and *** precision of the liquid transfer and temperature control was tested.A comparison between our device and a commercial kit for SARS-Cov-2 nucleic acid extraction was performed using real-time fluorescence reverse transcription polymerase chain reaction(RT-PCR).The entire process,from SARS-CoV-2 nucleic acid extraction to amplification,was *** The precision of the syringe transfer volume was 19.2±1.9μL(set value was 20),32.2±1.6(set value was 30),and 57.2±3.5(set value was 60).Temperature control in the amplification tube was measured at 60.0±0.0℃(set value was 60)and 95.1±0.2℃(set value was 95)***-Cov-2 nucleic acid extraction yield through the device was 7.10×10^(6) copies/mL,while a commercial kit yielded 2.98×10^(6) copies/*** mean time to complete the entire assay,from SARS-CoV-2 nucleic acid extraction to amplification detection,was 36 min and 45 *** detection limit for SARS-CoV-2 nucleic acid was 250 copies/*** The integrated disposable devices may be used for SARS-CoV-2 Point-of-Care test(POCT).

关键词： An integrated disposable device SARS-Cov-2 Nucleic acid detection

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复杂性公共政策:范式变迁、研究框架与展望

政治学研究 2024年第2期 180-193,M0008页

作者：郑石明李红霞暨南大学公共管理学院广东省广州市510632 暨南大学公共政策研究院广东省广州市510632 佛山开放大学广东省佛山市528000

随着全球化和社会多元化的发展,各类组织的外部环境充满不确定性和复杂性,决策风险急剧上升,导致公共政策过程愈发复杂。社会系统的复杂性得到越来越多的学者重视,复杂性理论的研究如雨后春笋般出现。与传统公共政策不同,复杂性公共政... 详细信息

随着全球化和社会多元化的发展,各类组织的外部环境充满不确定性和复杂性,决策风险急剧上升,导致公共政策过程愈发复杂。社会系统的复杂性得到越来越多的学者重视,复杂性理论的研究如雨后春笋般出现。与传统公共政策不同,复杂性公共政策更加关注系统构成、环境氛围和组织变迁等动态复杂因素,可为公共政策研究提供全新的视野和研究范式。本文通过梳理复杂性公共政策的研究进展与演进逻辑,识别传统公共政策的困境,分析公共政策范式变迁的必然性与趋势,探讨复杂性公共政策研究的范式变迁动因、理论研究框架及其在公共政策领域的适用性,展望复杂性公共政策的未来,以期为公共政策研究寻找新的理论基础,提供新的思想启迪。

关键词：复杂性公共政策政策科学政策研究复杂性理论

飞龙掌血蜂蜜挥发性物质组成及关键香气物质分析

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食品科学 2024年第11期45卷 175-185页

作者：姜澳黎洪霞刘肇龙宋梅李娜陈兰珍资源昆虫高效养殖与利用全国重点实验室中国农业科学院蜜蜂研究所北京100093 农业农村部蜂产品质量安全风险评估实验室(北京) 北京100093

为明确中国特色中药材蜂蜜——飞龙掌血蜂蜜的挥发性物质组成及香气特征,利用阿贝折光仪、高效液相色谱仪、紫外分光光度计等分别对其水分含量、糖类含量、淀粉酶活性、抗氧化能力等指标进行测定。同时,利用顶空-固相微萃取结合气相色谱... 详细信息

为明确中国特色中药材蜂蜜——飞龙掌血蜂蜜的挥发性物质组成及香气特征,利用阿贝折光仪、高效液相色谱仪、紫外分光光度计等分别对其水分含量、糖类含量、淀粉酶活性、抗氧化能力等指标进行测定。同时,利用顶空-固相微萃取结合气相色谱-四极杆飞行时间质谱仪对其挥发性成分进行定性定量分析。结果表明:飞龙掌血蜂蜜样品的水分质量分数为(18.71±1.49)%,果糖和葡萄糖质量分数分别为(35.92±2.70)%和(35.85±2.51)%,1,1-二苯基-2-三硝基苯肼自由基和2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基的半清除浓度分别为(57.18±7.62)mg/mL和(247.68±40.50)mg/mL,淀粉酶活力为(11.84±3.38)mL/(g·h)。从飞龙掌血蜂蜜中共鉴定出176种挥发性物质,主要包括烃类52种、酯类29种、醇类21种、萜烯类21种、醛类17种和芳香族类12种等。其中苯甲醛、苯乙醇、1-辛烯-3-醇的含量较高,分别为8 181.9、4 483.1μg/kg和4 239.5μg/kg。经香气活度值分析鉴定出42种关键香气化合物(OAV>1),包括大马士酮、苯乙酸甲酯、α-水芹烯等,这些物质对飞龙掌血蜂蜜香气组成具有重要贡献。其中紫罗酮具有紫罗兰花香气,赋予了飞龙掌血蜂蜜独特的紫罗兰、覆盆子芳香味。飞龙掌血蜂蜜主要以花香味为主,辅以果香味、化学味和青香味的香气。综上,飞龙掌血蜂蜜的理化指标均满足相关标准,且挥发性成分种类丰富。本研究可为飞龙掌血蜂蜜品质评价提供数据支持,并为其他特色中药材蜂蜜的挖掘提供研究思路。

关键词：飞龙掌血蜂蜜顶空-固相微萃取-气相色谱-四极杆飞行时间质谱挥发性成分关键香气化合物