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Study on the microwave-assisted extraction of polyphenols from tea

Liyun WANG, Peiyong QIN, Yan HU,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 307-313 doi: 10.1007/s11705-009-0282-6

摘要: This study demonstrated a promising method for quickly extracting tea polyphenol (TP) by microwave-assisted extraction (MAE) technology. Some influential parameters, including MAE temperature, microwave power, concentration of extraction solvent, MAE time and the solid/liquid ratio, were investigated. The optimum condition of MAE was obtained by dual extraction with 60% ethanol (v/v) and the solid/liquid ratio 1:12 g/mL at 80°C for 10 minutes under the microwave power 600 W. The yield of TP was 96.5% under the described condition. Compared with traditional methods, including hot reflux extraction (HRE), ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE), the extraction time was saved 8 times than that of HRE, and the yield was increased by 17.5%. The extraction time at comparable levels of production was saved 2 times, and the energy consumption was one fourth that of UAE. The extraction time was saved 5 times than that of SFE, and the yield of TP was increased by 40%. Moreover, compared with MAE of TP studied by others, it decreased the solid/liquid ratio from 1 ∶ 20 to 1 ∶ 12 g/mL without 90-min pre-leaching time, and the yield of TP was increased by 6%–40%.

关键词: energy consumption     microwave-assisted extraction     optimum condition     pre-leaching     concentration    

Optimization of microwave-assisted extraction for picroside I and picroside II from

Pravin WAKTE,Ajit PATIL,Bhusari SACHIN,Munnaza QUAZI,Shraddha JABDE,Devanand SHINDE

《化学科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 445-453 doi: 10.1007/s11705-014-1458-2

摘要: The response surface methodology was employed to study the optimization of microwave-assisted extraction of picroside I and picroside II from Royle rhizomes. The effects of solid to solvent ratio, and extraction temperature, time and solvent on the yields of picroside I and picroside II have been investigated using Box-Behnken experimental design. The experimental data were fitted to second-order polynomial equations using multiple regression analysis and analyzed using the appropriate statistical method. By solving the regression equation and analyzing 3-D plots, the optimum extraction conditions were found to be: solid to solvent ratio, 10 : 90 (w/v); temperature, 60 °C; and extraction time, 60 s. Under the optimal conditions, the yields of picroside I and picroside II are 41.23 and 6.12 mg·g feed respectively, which are in good agreement with the predicted values. The ratio of solid to solvent significantly affects the yields of picroside I and picroside II. Application of microwave-assisted extraction of picroside I and picroside II from would dramatically reduce extraction time and solvent consumption.

关键词: Box-Behnken design     microwave-assisted extraction     picroside I     picroside II     Picrorrhiza kurroa    

Technologies for extracting lipids from oleaginous microorganisms for biodiesel production

Cunwen WANG, Lu CHEN, Bajpai RAKESH, Yuanhang QIN, Renliang LV

《能源前沿(英文)》 2012年 第6卷 第3期   页码 266-274 doi: 10.1007/s11708-012-0193-y

摘要: Recently, biodiesel has received much more attention. Soybean oil, rapeseed oil, palm oil and corn oil are primary feedstock for biodiesel production. However, biodiesel production from these traditional oil-rich crops is limited by land availability, climate, and environmental and social issues regarding the use of feed and food crops for fuel. Oleaginous microorganisms, including microalgae, bacteria, yeast and fungi can be cultivated with high lipid contents and used as promising feedstock for biodiesel production. However, the high cost of biodiesel production using oil microorganisms has been the biggest obstacle for its industrialization. The process of biodiesel production from microorganisms involves many steps, of which the lipids extraction is the most important and costly. Therefore, searching for an effective and economical extraction system is critical. Various approaches of lipids extraction are discussed in this review, including traditional extraction procedures such as solvent extraction, pressing and solvent integrated extraction, as well as some new procedures.

关键词: oleaginous microorganisms     biodiesel     solvent extraction     ultrasound-assisted extraction     microwave-assisted extraction     supercritical fluid extraction (SFE)    

Microwave-assisted catalytic oxidation of gaseous toluene with a Cu-Mn-Ce/cordierite honeycomb catalyst

Longli Bo, Shaoyuan Sun

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 385-392 doi: 10.1007/s11705-018-1738-3

摘要: A novel Cu-Mn-Ce/cordierite honeycomb catalyst was prepared by an incipient wetness method and the catalyst was characterized. The active ingredients were present as various spinel species of Cu, Mn and Ce oxides with different valences and they were unevenly dispersed over the surface of the catalyst. The catalytic oxidation of gaseous toluene was primarily investigated using a fixed bed reactor under microwave heating in the continuous flow mode. Under the optimal conditions of 6.7 wt-% loading of the active component, a bed temperature of 200°C, a flow rate of 0.12 m ·h and an initial concentration of toluene of 1000 mg·m , the removal and mineralization efficiencies of toluene were 98% and 70%, respectively. Thus the use of the microwave effectively improved the oxidation of toluene and this is attributed to dipole polarization and hotspot effects. After four consecutive cycles (a total of 1980 min), the Cu-Mn-Ce/cordierite catalyst still exhibited excellent catalytic activity and structural stability, and the toluene removal was higher than 90%. This work demonstrates the possibility of treating volatile organic compounds in exhaust gases by microwave-assisted catalytic oxidation.

关键词: microwave     catalytic oxidation     toluene     Cu-Mn-Ce/cordierite     mineralization    

Microwave-assisted catalyst-free hydrolysis of fibrous cellulose for deriving sugars and biochemicals

Songshan Jiang, Helen Daly, Huan Xiang, Ying Yan, Huiping Zhang, Christopher Hardacre, Xiaolei Fan

《化学科学与工程前沿(英文)》 2019年 第13卷 第4期   页码 718-726 doi: 10.1007/s11705-019-1804-5

摘要: Microwave (MW) assisted catalyst-free hydrolysis of fibrous cellulose (FC, cellulolysis) at 200°C promoted a cellulose conversion of ca 37.2% and quantitative production of valuable C5/C6 sugars (e.g , glucose) and the according platform biochemicals (e.g , 5-hydroxymethylfurfural), corresponding to an overall selectivity of 96.5%. Conversely, conventional hydrothermal cellulolysis under similar conditions was not effective, even after 24 h, carbonising the FC. Based on the systematic study of MW-assisted cellulolysis, the specific interaction between water molecules and macroscopic FC under the MW irradiation was proposed, accounting for the interpretation of the experimental observation. The kinetic energy of water molecules under the MW irradiation facilitated the C C (in the non-hindered surface CH OH groups) and C O C bond breaking (inside the cellulose cavities) in FC, producing primary cellulolysis products of xylose, glucose and cellobiose.

关键词: microwave     fibrous cellulose     hydrolysis     sugars     mechanism    

Microwave-assisted synthesis and antimicrobial activities of 2-aryl-3-(naphthalene-1 or 2-yl)-1,3-thiazolidin

Hua CHEN, Yanan LI, Jie BAI, Lian ZHAO, Xiangguo YUAN, Xiaoliu LI, Keqiang CAO

《化学科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 186-191 doi: 10.1007/s11705-009-0004-0

摘要: 2-aryl-3-(naphthalene-1 or 2-yl)-1,3-thiazolidin-4-ones and were synthesized in 41%-67% yield by using microwave-assisted one-pot protocol. The structures of the new compounds , , , , , , and - were confirmed by IR, NMR, MS, and elemental analysis. The antimicrobial activities of the compounds against pv. lachrymans (Smith et Bryan) Young, Dye & Wilkie, Pers., and Blum. were examined. Some of the compounds showed good antifungical activity against Blum.

关键词: microwave-assisted synthesis     naphthyl     thiazolidin-4-one     antimicrobial    

Microwave assisted synthesis of poly(2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) and its

Gautam SEN, G. Usha RANI, Sumit MISHRA

《化学科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 312-321 doi: 10.1007/s11705-013-1344-3

摘要: Poly(2-hydroxyethylmethacrylate) chains were grafted onto the backbone of agar using a microwave assisted method involving a combination of microwave irradiation and ceric ammonium nitrate to initiate the grafting reaction. The synthesized graft copolymers were characterized by intrinsic viscosity measurements, Fourier transform infrared spectroscopy, elemental analysis (C, H, N, O and S) and scanning electron microscopy. Ag-g-P(HEMA)-2 showed a much higher flocculation efficacy than agar. The optimized dosage of flocculation for Ag-g-P(HEMA)-2 in the wastewater was found to be 0.75 ppm. Compared to agar, Ag-g-P(HEMA)-2 was found to considerably reduce the pollutant load in the wastewater.

关键词: agar     flocculant     microwave assisted synthesis     jar test protocol     poly(HEMA) grafted agar     wastewater treatment    

Entity and relation extraction with rule-guided dictionary as domain knowledge

《工程管理前沿(英文)》   页码 610-622 doi: 10.1007/s42524-022-0226-0

摘要: Entity and relation extraction is an indispensable part of domain knowledge graph construction, which can serve relevant knowledge needs in a specific domain, such as providing support for product research, sales, risk control, and domain hotspot analysis. The existing entity and relation extraction methods that depend on pretrained models have shown promising performance on open datasets. However, the performance of these methods degrades when they face domain-specific datasets. Entity extraction models treat characters as basic semantic units while ignoring known character dependency in specific domains. Relation extraction is based on the hypothesis that the relations hidden in sentences are unified, thereby neglecting that relations may be diverse in different entity tuples. To address the problems above, this paper first introduced prior knowledge composed of domain dictionaries to enhance characters’ dependence. Second, domain rules were built to eliminate noise in entity relations and promote potential entity relation extraction. Finally, experiments were designed to verify the effectiveness of our proposed methods. Experimental results on two domains, including laser industry and unmanned ship, showed the superiority of our methods. The F1 value on laser industry entity, unmanned ship entity, laser industry relation, and unmanned ship relation datasets is improved by +1%, +6%, +2%, and +1%, respectively. In addition, the extraction accuracy of entity relation triplet reaches 83% and 76% on laser industry entity pair and unmanned ship entity pair datasets, respectively.

关键词: entity extraction     relation extraction     prior knowledge     domain rule    

Development of lunar regolith composite and structure via laser-assisted sintering

《机械工程前沿(英文)》 doi: 10.1007/s11465-021-0662-2

摘要: Aiming at the exploration and resource utilization activities on the Moon, in situ resource utilization and in situ manufacturing are proposed to minimize the dependence on the ground transportation supplies. In this paper, a laser-assisted additive manufacturing process is developed to fabricate lunar regolith composites with PA12/SiO2 mixing powders. The process parameters and composite material compositions are optimized in an appropriate range through orthogonal experiments to establish the relationship of process–structure–property for lunar regolith composites. The optimal combination of composite material compositions and process parameters are mixing ratio of 50/50 in volume, laser power of 30 W, scanning speed of 3500 mm/s, and scanning hatch space of 0.2 mm. The maximum tensile strength of lunar regolith composites reaches 9.248 MPa, and the maximum depth of surface variation is 120.79 μm, which indicates poor powder fusion and sintering quality. Thereafter, the mechanical properties of laser-sintered lunar regolith composites are implemented to the topology optimization design of complex structures. The effectiveness and the feasibility of this laser-assisted process are potentially developed for future lightweight design and manufacturing of the solar panel installed on the lunar rover.

关键词: in situ manufacturing     laser-assisted powder fusion process     mechanical properties     topological structure design    

Guidelines for navigation-assisted spine surgery

Bo Liu, Da He, Yajun Liu, Xiaoguang Han, Jingwei Zhao, Mingxing International Society for Computer Assisted

《医学前沿(英文)》 2020年 第14卷 第4期   页码 518-527 doi: 10.1007/s11684-020-0775-8

摘要: Spinal surgery is a technically demanding and challenging procedure because of the complicated anatomical structures of the spine and its proximity to several important tissues. Surgical landmarks and fluoroscopy have been used for pedicle screw insertion but are found to produce inaccuracies in placement. Improving the safety and accuracy of spinal surgery has increasingly become a clinical concern. Computer-assisted navigation is an extension and application of precision medicine in orthopaedic surgery and has significantly improved the accuracy of spinal surgery. However, no clinical guidelines have been published for this relatively new and fast-growing technique, thus potentially limiting its adoption. In accordance with the consensus of consultant specialists, literature reviews, and our local experience, these guidelines include the basic concepts of the navigation system, workflow of navigation-assisted spinal surgery, some common pitfalls, and recommended solutions. This work helps to standardize navigation-assisted spinal surgery, improve its clinical efficiency and precision, and shorten the clinical learning curve.

关键词: guidelines     spine surgery     computer-assisted navigation    

Decomposition of perfluorooctanoic acid by microwave-activated persulfate: Effects of temperature, pH

Yuchi LEE, Shanglien LO, Jeff KUO, Chinghong HSIEH

《环境科学与工程前沿(英文)》 2012年 第6卷 第1期   页码 17-25 doi: 10.1007/s11783-011-0371-x

摘要: Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate ( ) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate the effects of pH (pH= 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01–0.15 mol·L ), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA degradation. When chloride concentrations were less than 0.04 mol·L at 90°C and 0.06 mol·L at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels, PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature.

关键词: microwave     perfluorooctanoic acid     pH     persulfate     chloride ions     perfluorocarboxylic acids    

Characterisation of a microwave induced plasma torch for glass surface modification

Adam BENNETT, Nan YU, Fengzhou FANG, Marco CASTELLI, Guoda CHEN, Alessio BALLERI, Takuya URAYAMA

《机械工程前沿(英文)》 2021年 第16卷 第1期   页码 122-132 doi: 10.1007/s11465-020-0603-5

摘要: Microwave induced plasma torches find wide applications in material and chemical analysis. Investigation of a coaxial electrode microwave induced plasma (CE–MIP) torch is conducted in this study, making it available for glass surface modification and polishing. A dedicated nozzle is designed to inject secondary gases into the main plasma jet. This study details the adaptation of a characterisation process for CE–MIP technology. Microwave spectrum analysis is used to create a polar plot of the microwave energy being emitted from the coaxial electrode, where the microwave energy couples with the gas to generate the plasma jet. Optical emission spectroscopy analysis is also employed to create spatial maps of the photonic intensity distribution within the plasma jet when different additional gases are injected into it. The CE–MIP torch is experimentally tested for surface energy modification on glass where it creates a super-hydrophilic surface.

关键词: microwave induced plasma     spectrum analysis     surface modification    

Soybean drying characteristics in microwave rotary dryer with forced convection

Ruifang WANG, Zhanyong LI, Yanhua LI, Jingsheng YE

《化学科学与工程前沿(英文)》 2009年 第3卷 第3期   页码 289-292 doi: 10.1007/s11705-009-0022-y

摘要: A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m ·h or specific microwave energy lower than 0.4 kW·kg in the present experiments.

关键词: cracking     microwave     rotary drying     soybean    

Energy field-assisted high-speed dry milling green machining technology for difficult-to-machine metal

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0744-9

摘要: Energy field-assisted machining technology has the potential to overcome the limitations of machining difficult-to-machine metal materials, such as poor machinability, low cutting efficiency, and high energy consumption. High-speed dry milling has emerged as a typical green processing technology due to its high processing efficiency and avoidance of cutting fluids. However, the lack of necessary cooling and lubrication in high-speed dry milling makes it difficult to meet the continuous milling requirements for difficult-to-machine metal materials. The introduction of advanced energy-field-assisted green processing technology can improve the machinability of such metallic materials and achieve efficient precision manufacturing, making it a focus of academic and industrial research. In this review, the characteristics and limitations of high-speed dry milling of difficult-to-machine metal materials, including titanium alloys, nickel-based alloys, and high-strength steel, are systematically explored. The laser energy field, ultrasonic energy field, and cryogenic minimum quantity lubrication energy fields are introduced. By analyzing the effects of changing the energy field and cutting parameters on tool wear, chip morphology, cutting force, temperature, and surface quality of the workpiece during milling, the superiority of energy-field-assisted milling of difficult-to-machine metal materials is demonstrated. Finally, the shortcomings and technical challenges of energy-field-assisted milling are summarized in detail, providing feasible ideas for realizing multi-energy field collaborative green machining of difficult-to-machine metal materials in the future.

关键词: difficult-to-machine metal material     green machining     high-speed dry milling     laser energy field-assisted milling     ultrasonic energy field-assisted milling     cryogenic minimum quantity lubrication energy field-assisted milling    

An extraction- assay system: Evaluation on flavonols in plant resistance to Pb and Cd by supercriticalextraction- gas chromatography

Xu Zhang, Huanhuan Yang, Xinlei Wang, Wen Song, Zhaojie Cui

《环境科学与工程前沿(英文)》 2018年 第12卷 第4期 doi: 10.1007/s11783-018-1059-2

摘要:

SFE-GC system is established for flavonols assessment.

Optimal parameters of SFE-GC are evaluated and determined.

Quercetin and kaempferol are detected in plant under heavy metal stress.

Gene expression analysis shows consistent regularity with content of flavonols.

ROS level is applied for elaborating the plant resistance status.

关键词: Flavonols     Heavy metal     Supercritical carbon dioxide extraction (SFE)     GC     Plant resistance    

标题 作者 时间 类型 操作

Study on the microwave-assisted extraction of polyphenols from tea

Liyun WANG, Peiyong QIN, Yan HU,

期刊论文

Optimization of microwave-assisted extraction for picroside I and picroside II from

Pravin WAKTE,Ajit PATIL,Bhusari SACHIN,Munnaza QUAZI,Shraddha JABDE,Devanand SHINDE

期刊论文

Technologies for extracting lipids from oleaginous microorganisms for biodiesel production

Cunwen WANG, Lu CHEN, Bajpai RAKESH, Yuanhang QIN, Renliang LV

期刊论文

Microwave-assisted catalytic oxidation of gaseous toluene with a Cu-Mn-Ce/cordierite honeycomb catalyst

Longli Bo, Shaoyuan Sun

期刊论文

Microwave-assisted catalyst-free hydrolysis of fibrous cellulose for deriving sugars and biochemicals

Songshan Jiang, Helen Daly, Huan Xiang, Ying Yan, Huiping Zhang, Christopher Hardacre, Xiaolei Fan

期刊论文

Microwave-assisted synthesis and antimicrobial activities of 2-aryl-3-(naphthalene-1 or 2-yl)-1,3-thiazolidin

Hua CHEN, Yanan LI, Jie BAI, Lian ZHAO, Xiangguo YUAN, Xiaoliu LI, Keqiang CAO

期刊论文

Microwave assisted synthesis of poly(2-hydroxyethylmethacrylate) grafted agar (Ag-g-P(HEMA)) and its

Gautam SEN, G. Usha RANI, Sumit MISHRA

期刊论文

Entity and relation extraction with rule-guided dictionary as domain knowledge

期刊论文

Development of lunar regolith composite and structure via laser-assisted sintering

期刊论文

Guidelines for navigation-assisted spine surgery

Bo Liu, Da He, Yajun Liu, Xiaoguang Han, Jingwei Zhao, Mingxing International Society for Computer Assisted

期刊论文

Decomposition of perfluorooctanoic acid by microwave-activated persulfate: Effects of temperature, pH

Yuchi LEE, Shanglien LO, Jeff KUO, Chinghong HSIEH

期刊论文

Characterisation of a microwave induced plasma torch for glass surface modification

Adam BENNETT, Nan YU, Fengzhou FANG, Marco CASTELLI, Guoda CHEN, Alessio BALLERI, Takuya URAYAMA

期刊论文

Soybean drying characteristics in microwave rotary dryer with forced convection

Ruifang WANG, Zhanyong LI, Yanhua LI, Jingsheng YE

期刊论文

Energy field-assisted high-speed dry milling green machining technology for difficult-to-machine metal

期刊论文

An extraction- assay system: Evaluation on flavonols in plant resistance to Pb and Cd by supercriticalextraction- gas chromatography

Xu Zhang, Huanhuan Yang, Xinlei Wang, Wen Song, Zhaojie Cui

期刊论文