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Interfacial induction and regulation for microscale crystallization process: a critical review

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 838-853 doi: 10.1007/s11705-021-2129-8

摘要: Microscale crystallization is at the frontier of chemical engineering, material science, and biochemical research and is affected by many factors. The precise regulation and control of microscale crystal processes is still a major challenge. In the heterogeneous induced nucleation process, the chemical and micro/nanostructural characteristics of the interface play a dominant role. Ideal crystal products can be obtained by modifying the interface characteristics, which has been proven to be a promising strategy. This review illustrates the application of interface properties, including chemical characteristics (hydrophobicity and functional groups) and the morphology of micro/nanostructures (rough structure and cavities, pore shape and pore size, surface porosity, channels), in various microscale crystallization controls and process intensification. Finally, possible future research and development directions are outlined to emphasize the importance of interfacial crystallization control and regulation for crystal engineering.

关键词: interfacial crystallization     heterogeneous nucleation     supersaturation     micro/nanostructure     process control and intensification    

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

Shiquan SHAN, Chuyang CHEN, Peter G. LOUTZENHISER, Devesh RANJAN, Zhijun ZHOU, Zhuomin M. ZHANG

《能源前沿(英文)》 2020年 第14卷 第3期   页码 482-509 doi: 10.1007/s11708-020-0693-0

摘要: Micro/nanostructures play a key role in tuning the radiative properties of materials and have been applied to high-temperature energy conversion systems for improved performance. Among the various radiative properties, spectral emittance is of integral importance for the design and analysis of materials that function as radiative absorbers or emitters. This paper presents an overview of the spectral emittance measurement techniques using both the direct and indirect methods. Besides, several micro/nanostructures are also introduced, and a special emphasis is placed on the emissometers developed for characterizing engineered micro/nanostructures in high-temperature applications (e.g., solar energy conversion and thermophotovoltaic devices). In addition, both experimental facilities and measured results for different materials are summarized. Furthermore, future prospects in developing instrumentation and micro/nanostructured surfaces for practical applications are also outlined. This paper provides a comprehensive source of information for the application of micro/nanostructures in high-temperature energy conversion engineering.

关键词: concentrating solar power (CSP)     emittance measurements     high temperature     micro/nanostructure     selective absorber     selective emitter     thermophotovoltaics (TPV)    

Fabrication of titania thin film with composite nanostructure and its ability to photodegrade rhodamine

ZHANG Gaojie, WU Jinming, LIU Shaoguang, YAN Mi

《化学科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 44-48 doi: 10.1007/s11705-008-0001-8

摘要: A titania nanorod film was synthesized by direct oxidation of metallic Ti with hydrogen peroxide solution under a low temperature. Titania nanoparticles were then filled into the gaps among the nanorods through an infiltration sol-gel procedure to form a composite titania film with an ordered nanostructure. X-ray diffraction spectra indicate that the composite film was a mixture of anatase and rutile while the titania film obtained by only using a sol-gel procedure was pure anatase. Field emission scanning electron microscopy observations show that titania nanoparticles were embedded into the titania nanorod film. Photoluminescence spectra suggest the enhanced separation of electron and hole pairs for the obtained composite titania film over the corresponding titania nanorod film. The composite titania film exhibited improved ability to photodegrade rhodamine B in water compared with the titania nanorod film. The apparent photodegradation rate constant, fitting a pseudo-first-order, was 3 times of that obtained by the sol-gel derived titania film at the same weight. The improved photocatalytic activity for the composite titania film could be attributed to the enhanced separation of electron and hole pairs due to the embedding of the titania nanoparticles within the titania nanorods.

关键词: constant     weight     apparent photodegradation     hydrogen     nanorod    

Investigation of nanostructure of konjac-based water absorbents with atomic force microscopy

Shengrong GENG, Ruotai LIN, Mingli CHEN, Shaoyang LIU, Yifen WANG,

《化学科学与工程前沿(英文)》 2009年 第3卷 第4期   页码 357-362 doi: 10.1007/s11705-009-0245-y

摘要: Atomic force microscopy technology is gradually spreading to almost all aspects, including food science and technology, since it was first invented in 1986. In this study, this powerful instrument was applied to image nanostructures of three water absorbents—original konjac powder, konjac powder grafted with acrylic acid using Co γ-irradiation and regenerated grafted powder. Water absorption capacities and the rates of the three absorbents were also determined in this work. Original konjac powder could only absorb 60 times (w/w) of water, while 270 times for the grafted absorbent and 360 times for the regenerated absorbent. The initial water absorption rates in both tap and distilled water were high, but the rate decreased steeply as time elapsed. After 20min, the absorbent was close to saturated status. These physical properties were in accordance with the nanostructures of these three water absorbents.

关键词: regenerated grafted     -irradiation     grafted     grafted absorbent     accordance    

Flexible micro flow sensor for micro aerial vehicles

Rong ZHU, Ruiyi QUE, Peng LIU

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 539-545 doi: 10.1007/s11465-017-0427-0

摘要:

This article summarizes our studies on micro flow sensors fabricated on a flexible polyimide circuit board by a low-cost hybrid process of thin-film deposition and circuit printing. The micro flow sensor has merits of flexibility, structural simplicity, easy integrability with circuits, and good sensing performance. The sensor, which adheres to an object surface, can detect the surface flow around the object. In our study, we install the fabricated micro flow sensors on micro aerial vehicles (MAVs) to detect the surface flow variation around the aircraft wing and deduce the aerodynamic parameters of the MAVs in flight. Wind tunnel experiments using the sensors integrated with the MAVs are also conducted.

关键词: micro flow sensor     flexible sensor     surface flow sensing     aerodynamic parameter     micro aerial vehicle (MAV)    

Recent advances in SERS detection of perchlorate

Jumin Hao, Xiaoguang Meng

《化学科学与工程前沿(英文)》 2017年 第11卷 第3期   页码 448-464 doi: 10.1007/s11705-017-1611-9

摘要: Perchlorate has recently emerged as a widespread environmental contaminant of healthy concern. Development of novel detection methods for perchlorate with the potential for field use has been an urgent need. The investigation has shown that surface-enhanced Raman scattering (SERS) technique has great potential to become a practical analysis tool for the rapid screening and routine monitoring of perchlorate in the field, particularly when coupled with portable/handheld Raman spectrometers. In this review article, we summarize progress made in SERS analysis of perchlorate in water and other media with an emphasis on the development of SERS substrates for perchlorate detection. The potential of this technique for fast screening and field testing of perchlorate-contaminated environmental samples is discussed. The challenges and possible solutions are also addressed, aiming to provide a better understanding on the development directions in the research field.

关键词: perchlorate     SERS     detection     substrate     modification     nanostructure    

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 146-149 doi: 10.1007/s11465-013-0260-z

摘要:

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 μm . It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

关键词: Micro-Electro-Mechanical Systems (MEMS)     micro accelerometer     force-balanced micro accelerometer     frequency     error sensitivity    

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 396-401 doi: 10.1007/s11708-009-0049-2

摘要: Numerical simulations of flowing and boiling in micro channels are presented, including the modeling of bubble dynamics of nucleate boiling, and a description of the interface of two phases with the volume-of-fluid (VOF). The two calculated cases are compared with related experimental data in literature. Some simulated results are found corresponding well to the experimental data. The simulated results also show the details of 3-dimensional heat transfer and the flow in micro channels, which are helpful to the investigation of the mechanism of two-phase heat transfer and flow in micro channels.

关键词: volume-of-fluid (VOF)     micro channel     nucleate boiling     bubble dynamics     simulation    

Dynamical research on spherical micro actuator with piezoelectric ceramic stacks drivers

ZHANG Ruihua, CHEN Haichu

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 433-438 doi: 10.1007/s11465-007-0074-y

摘要: This paper develops a 30 mm × 30 mm × 50 mm spherical micro actuator driven by piezoelectric ceramic stacks (PZT), and analyzes its dynamic performances. First, the space coordinate relationship of the spherical micro actuator and a dynamic model are set up. Second, The Runge-Kutta arithmetic is used to calculate the dynamical parameters of the micro actuator; the SIMULINK module of MATLAB is used to build the dynamical simulating model and then simulate it. Third, an experimental sample of the spherical micro actuator is developed, a micromanipulator is integrated with a micro-gripper based on the sample spherical micro actuator, and the experimental research on the micro assembly is conducted between a micro shaft of 180 μm and a micro spindle sleeve of 200 μm. Finally, the characteristics of the spherical micro actuator influenced by the mass of the metal sphere of the micro actuator, driving signal frequency, friction coefficient of the contact surface between the metal sphere and the friction block of the micro driving unit are analyzed. The experimental results indicate that the rotation resolution of the micro actuator reaches 0.000 1°, the rotation positioning precision reaches 0.000 5°, and the maximum working frequency is about 1200 Hz. The experimental results validate the back rotation vibration model of the spherical micro actuator. The micromanipulator integrated by the spherical micro actuator can meet the requirements of precise micro operation and assembly for micro electro mechanical systems (MEMS) or other microelements in micro degree fields.

关键词: spherical     micro-gripper     friction coefficient     dynamic     frequency    

Nanostructure and reactivity of soot from biofuel 2,5-dimethylfuran pyrolysis with CO

Lijie ZHANG, Kaixuan YANG, Rui ZHAO, Mingfei CHEN, Yaoyao YING, Dong LIU

《能源前沿(英文)》 2022年 第16卷 第2期   页码 292-306 doi: 10.1007/s11708-020-0658-3

摘要: This paper investigated the nanostructure and oxidation reactivity of soot generated from biofuel 2,5-dimethylfuran pyrolysis with different CO additions and different temperatures in a quartz tube flow reactor. The morphology and nanostructure of soot samples were characterized by a low and a high resolution transmission electron spectroscopy (TEM and HRTEM) and an X-ray diffraction (XRD). The oxidation reactivity of these samples was explored by a thermogravimetric analyzer (TGA). Different soot samples were collected in the tail of the tube. With the increase of temperature, the soot showed a smaller mean particle diameter, a longer fringe length, and a lower fringe tortuosity, as well as a higher degree of graphization. However, the variation of soot nanostructures resulting from different CO additions was not linear. Compared with 0%, 50%, and 100% CO additions at one fixed temperature, the soot collected from the 10% CO addition has the highest degree of graphization and crystallization. At three temperatures of 1173 K, 1223 K, and 1273 K, the mean values of fringe length distribution displayed a ranking of 10% CO >100% CO >50% CO while the mean particle diameters showed the same order. Furthermore, the oxidation reactivity of different soot samples decreased in the ranking of 50% CO addition>100% CO addition>10% CO addition, which was equal to the ranking of mean values of fringe tortuosity distribution. The result further confirmed the close relationship between soot nanostructure and oxidation reactivity.

关键词: 2     5-dimethylfuran pyrolysis     soot     CO2 addition     nanostructure     reactivity    

Laboratory assessment of Alaska aggregates using Micro-Deval test

Jenny LIU,Sheng ZHAO,Anthony MULLIN

《结构与土木工程前沿(英文)》 2017年 第11卷 第1期   页码 27-34 doi: 10.1007/s11709-016-0359-5

摘要: Aggregates suitable for use in asphalt concrete (AC) pavement construction must meet durability criteria. Thus, it is critical to select appropriate tests to properly characterize aggregate durability. In Alaska, durability tests currently being used for aggregates in AC pavement include Los Angeles (LA) abrasion test, sulfate soundness test and Washington degradation test. However, there have long been concerns arising over Washington degradation test used as an acceptance tool, motivating pavement practitioners to seek more suitable alternatives. This paper presents a study to investigate the feasibility of using Micro-Deval test, commonly used in other states, to evaluate the durability of Alaskan aggregates in AC pavement as well as its potential to replace Washington degradation test. Micro-Deval test, Washington degradation test and other tests currently specified in Alaska were conducted on aggregates from 16 batches representing statewide sources. Based on the testing results, it is found that using Micro-Deval test for durability assessment of Alaska aggregates was feasible and reproducible, and a high potential was revealed to use Micro-Deval test to replace Washington degradation test in Alaska. It is recommended that Micro-Deval test be considered as an additional test for a certain period, but in the long run should be used along with current LA abrasion and sulfate soundness tests to provide a more desirable durability assessment of Alaska aggregates used in AC pavement.

关键词: aggregate durability     Washington degradation test     Micro-Deval test    

Characterization of micro-mixing in a novel impinging streams reactor

Hui HU, Zhiming CHEN, Zhen JIAO

《化学科学与工程前沿(英文)》 2009年 第3卷 第1期   页码 58-64 doi: 10.1007/s11705-009-0106-8

摘要: This paper presents an experimental investigation of a novel impinging stream reactor (ISR) with the aim of high mixing intensity. The integral mixing quality in the reactor was measured with the iodide-iodate reaction and showed excellent mixing performance. The impact of the operating parameters, such as fluxes, circulation and inter-nozzle distances, was investigated in terms of segregation index. The results showed that the increase of flux, the decrease of inter-nozzle distance and a suitable circulation can improve the micro-mixing efficiency. Based on turbulence theory, it was estimated that the characteristic micro-mixing time was 0.002—0.02 s, which was much shorter than that in the stirred tank reactor. The micro-mixing time was related to the segregation index, which was in good agreement with those in the literature.

关键词: micro-mixing     impinging streams reactor     turbulent mixing     mass transfer    

Recent advances in micro- and nano-machining technologies

Shang GAO, Han HUANG

《机械工程前沿(英文)》 2017年 第12卷 第1期   页码 18-32 doi: 10.1007/s11465-017-0410-9

摘要:

Device miniaturization is an emerging advanced technology in the 21st century. The miniaturization of devices in different fields requires production of micro- and nano-scale components. The features of these components range from the sub-micron to a few hundred microns with high tolerance to many engineering materials. These fields mainly include optics, electronics, medicine, bio-technology, communications, and avionics. This paper reviewed the recent advances in micro- and nano-machining technologies, including micro-cutting, micro-electrical-discharge machining, laser micro-machining, and focused ion beam machining. The four machining technologies were also compared in terms of machining efficiency, workpiece materials being machined, minimum feature size, maximum aspect ratio, and surface finish.

关键词: micro machining     cutting     electro discharge machining (EDM)     laser machining     focused ion beam (FIB)    

Recent progress on nanostructure-based broadband absorbers and their solar energy thermal utilization

Tong Zhang, Shan-Jiang Wang, Xiao-Yang Zhang, Ming Fu, Yi Yang, Wen Chen, Dan Su

《化学科学与工程前沿(英文)》 2021年 第15卷 第1期   页码 35-48 doi: 10.1007/s11705-020-1937-6

摘要: Nanostructure-based broadband absorbers are prominently attractive in various research fields such as nanomaterials, nanofabrication, nanophotonics and energy utilization. A highly efficient light absorption in wider wavelength ranges makes such absorbers useful in many solar energy harvesting applications. In this review, we present recent advances of broadband absorbers which absorb light by nanostructures. We start from the mechanism and design strategies of broadband absorbers based on different materials such as carbon-based, plasmonic or dielectric materials and then reviewed recent progress of solar energy thermal utilization dependent on the superior photo-heat conversion capacity of broadband absorbers which may significantly influence the future development of solar energy utilization, seawater purification and photoelectronic device design.

关键词: nanostructured broadband absorbers     solar energy harvesting     thermal utilization    

Special issue: Micro-electromechanical systems (MEMS)

Zhuangde JIANG

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 457-458 doi: 10.1007/s11465-017-0492-4

标题 作者 时间 类型 操作

Interfacial induction and regulation for microscale crystallization process: a critical review

期刊论文

Spectral emittance measurements of micro/nanostructures in energy conversion: a review

Shiquan SHAN, Chuyang CHEN, Peter G. LOUTZENHISER, Devesh RANJAN, Zhijun ZHOU, Zhuomin M. ZHANG

期刊论文

Fabrication of titania thin film with composite nanostructure and its ability to photodegrade rhodamine

ZHANG Gaojie, WU Jinming, LIU Shaoguang, YAN Mi

期刊论文

Investigation of nanostructure of konjac-based water absorbents with atomic force microscopy

Shengrong GENG, Ruotai LIN, Mingli CHEN, Shaoyang LIU, Yifen WANG,

期刊论文

Flexible micro flow sensor for micro aerial vehicles

Rong ZHU, Ruiyi QUE, Peng LIU

期刊论文

Recent advances in SERS detection of perchlorate

Jumin Hao, Xiaoguang Meng

期刊论文

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

期刊论文

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

期刊论文

Dynamical research on spherical micro actuator with piezoelectric ceramic stacks drivers

ZHANG Ruihua, CHEN Haichu

期刊论文

Nanostructure and reactivity of soot from biofuel 2,5-dimethylfuran pyrolysis with CO

Lijie ZHANG, Kaixuan YANG, Rui ZHAO, Mingfei CHEN, Yaoyao YING, Dong LIU

期刊论文

Laboratory assessment of Alaska aggregates using Micro-Deval test

Jenny LIU,Sheng ZHAO,Anthony MULLIN

期刊论文

Characterization of micro-mixing in a novel impinging streams reactor

Hui HU, Zhiming CHEN, Zhen JIAO

期刊论文

Recent advances in micro- and nano-machining technologies

Shang GAO, Han HUANG

期刊论文

Recent progress on nanostructure-based broadband absorbers and their solar energy thermal utilization

Tong Zhang, Shan-Jiang Wang, Xiao-Yang Zhang, Ming Fu, Yi Yang, Wen Chen, Dan Su

期刊论文

Special issue: Micro-electromechanical systems (MEMS)

Zhuangde JIANG

期刊论文