A robotic multiple-shape-memory ionic polymer–metal composite (IPMC) actuator: modeling approach

Shen, Qi,Stalbaum, Tyler,Minaian, Nazanin,Oh, Il-Kwon,Kim, Kwang J IOP 2019 Smart materials & structures Vol.28 No.1

<P>The multiple-shape-memory ionic polymer–metal composite (MSM-IPMC) actuator can demonstrate complex 3D deformation. The MSM-IPMC has two distinct characteristics, which are the electromechanical actuation effect and the thermal-mechanical shape memory effect. The bending, twisting, and oscillating motions of the actuator could be controlled simultaneously or separately by means of thermal-mechanical and electromechanical transduction. In this study, a theoretical model for the MSM-IPMC was developed and experimentally investigated. Based on previous studies on the electromechanical actuation effect of ionic polymer–metal composite (IPMC), a comprehensive physics-based model of MSM-IPMC which couples the actuation effect and the multiple shape memory effect was developed. To verify the model, an MSM-IPMC sample was prepared and used in experimental testing. The simulation results were shown to be in good agreement with the experimental results obtained. The multiple shape memory and recovery rate of three different polymers, namely the Nafion, Aquivion and GEFC of different ions, which are the hydrogen, lithium and sodium, were also tested. Based on the results, it is shown that all the polymers demonstrate the multiple shape memory effect with varying amounts of programmable shapes. The ion type was shown to have an influence on the broad glass transition range of the polymers, which in turn dictated the number of possible programmable shapes for each membrane. The current study is beneficial for the better understanding of the multiple shape memory effect of MSM-IPMC.</P>

A Colorimetric and Fluorescent pH Probe for Extremely Acidic Conditions and its Application in pH Test Paper

Qi-Hua You,Jinhai Shen,Ganping Shen,Liyun Peng,Yuanqin Lu,Qi Fu,Yuqing Xu,Lei Zhang 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.3

Here, we report a highly water-soluble colorimetric and fluorescent pH probe that works in the pH range 0.2–3.0. The probe showed a rapid response, high stability, and excellent reversibility to acidity. Moreover, the fluorescence of probe was not influenced by the existence of high concentration of cations. The pKa of probe was calculated to be 2.25 ± 0.06. Furthermore, the pH test papers coated with the probe exhibited a distinct color change in acidic conditions.

Theoretical and experimental investigation of the shape memory properties of an ionic polymer–metal composite

Shen, Qi,Palmre, Viljar,Kim, Kwang J,Oh, Il-Kwon Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.4

<P>An ionic polymer–metal composite (IPMC) is typically based on a Nafion membrane with electrode plating on both sides and has a promising potential for biomimetic robotics, biomedical devices and human affinity applications. In this paper, the shape memory properties of IPMC were theoretically and experimentally studied. We presented the multiple shape memory properties of a Nafion cylinder. A physics based model of the IPMC was proposed. The free energy density theory was utilized to analyze the shape properties of the IPMC. To verify the model, IPMC samples with Nafion as the base membrane were prepared and experiments were conducted. A simulation of the model was performed and the results were compared with the experimental data. It was successfully demonstrated that the theoretical model can well explain the shape memory properties of the IPMC. The results showed that the reheat glass transition temperature of the IPMC is lower than the programming temperature. It was also found that the back-relaxation of the IPMC decreases as the programming temperature increases. The current study may be useful in order to better understand the shape memory effect of IPMC.</P>

FORMATION OF II–VI SEMICONDUCTOR NANOCRYSTALS WITH TUNABLE VISIBLE EMISSION IN AQUEOUS SOLUTION PROMOTED BY HYDRAZINE

QI-HUI SHEN,YAN LIU,XI YU,XIAO-YANG LIU,MING-QIANG ZOU,JIN-FENG LI,JIAN-GUANG ZHOU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6

II?VI Semiconductor nanocrystals (NCs) with tunable visible emission, such as CdS, CdSe and CdTe, were synthesized in aqueous solution using thiols as capping molecules. Hydrazine was found to promote the growth of NCs through a special mechanism. In only a few hours, the synthesis process was completed at room temperature. Under moderate conditions, the capping molecules not only changed the growth rate of NCs simply by varying the concentration, but also altered the spectral properties of NCs. The capping molecules with amino groups were propitious to the growth of CdS NCs, whereas the kinetic growth of CdS NCs was more a®ected by the surface passivation e±ciency of NCs than by steric hindrance in the system. The fastest growth of the CdS NCs was achieved when glutathione was used as a capping molecule, while the emission of CdS and CdSe NCs were shown to remain steady and tunable using the same capping molecule. The growth rate of 3-mercaptopropionic acid-capped CdS and CdSe NCs slowed down signi¯-cantly, while CdTe NCs were obtained with excellent emission properties when capped with the same molecule. Furthermore, our approach will also be useful for the study of the kinetic growth of NCs in aqueous solution.

Excess trehalose and glucose affects chitin metabolism in brown planthopper (Nilaparvata lugens)

Qi-Da Shen,Meng-Meng Yang,Guo-Qiang Xie,Hui-JuanWang,Lu Zhang,Ling-Yu Qiu,Shi-GuiWang,Bin Tang 한국응용곤충학회 2017 Journal of Asia-Pacific Entomology Vol.20 No.2

Trehalose is a non-reducing disaccharide that is hydrolyzed by trehalase to yield two glucose molecules. Trehalase is the first enzyme involved in the chitin biosynthesis pathway, and it plays a pivotal role in insect growth and molting. In this study, Nilaparvata lugens, an economically important rice pest in Southeast Asia, was injectedwith trehalose or glucose to investigate their effects on chitin metabolism. Excess trehalose and glucose significantly increased the rate of deformity (molting and/or wing deformities) and mortality in N. lugens. Trehalose, glycogen, and glucose contents were also significantly decreased in N. lugens treated with trehalose or glucose. Chitin content and the expression of NlHK, NlUAP, NlG6PI1, NlGFAT, NlGNPNA, NlPGM1, NlPGM2, NlCHS1, NlCHS1a, NlCHS1b, NlCht3, NlCht4, NlCht6, and NlCht7 were significantly decreased, whereas the expression of NlCht2, NlIDGF, and NlENGase was significantly increased in treated insects. Furthermore, a significant increase in the expression of NlTRE1-1, NlTRE2, and NlTPS1 and a decrease, in the expression of NlTPS2 were observed. Results of this study suggested that excess trehalose and glucose could affect chitin metabolism by regulating the expression of pivotal genes to decrease the chitin content, resulting in the inability of N. lugens to complete its molting process.

Significant Differences in the Clinicopathological Characteristics and Survival of Gastric Cancer Patients from Two Cancer Centers in China and Korea

Shen, Zhan Long,Song, Kyo Young,Ye, Ying Jiang,Xie, Qi Wei,Liang, Bin,Jiang, Kewei,Park, Cho Hyun,Wang, Shan The Korean Gastric Cancer Association 2015 Journal of gastric cancer Vol.15 No.1

Purpose: To compare the clinicopathological data and long-term survival of gastric cancer patients in China and Korea. Materials and Methods: Patients who had undergone gastrectomy for gastric cancer between 1998 and 2009 in 2 high-volume institutions in both China (n=1,637) and Korea (n=2,231) were retrospectively evaluated. Clinicopathological variables, overall survival (OS), progression-free survival (PFS), and surgery-related complications were assessed for all patients and compared between the 2 institutions. Results: Chinese patients included in the study were significantly older and had a significantly lower body mass index (BMI) than the Korean patients. Esophagogastric junction tumors were more frequent in Chinese patients. However, the number of patients with stage I gastric cancer, the number of harvested lymph nodes, and the number of total gastrectomies were significantly higher in the Korean population. Korean patients also presented with fewer undifferentiated tumors than Chinese patients. Furthermore, Korean patients had prolonged OS and PFS for stage III cancers only. BMI, tumor-node-metastasis (TNM) stage, tumor invasion, number of positive lymph nodes, and distant metastases were all independent factors affecting OS and PFS. Conclusions: Although China and Korea are neighboring Asian countries, the clinicopathological characteristics of Chinese patients are significantly different from those of Korean patients. Korean gastric cancer patients had longer OS and PFS than Chinese patients. Influencing factors included TNM stage, tumor invasion, and lymph node metastasis.

Intercomparison of ADC-Lite Images on UAV and TM Simulation Data for Soybean Leaf Area Index Retrieval

Qi Zhang,Zhongbin Su,Guijun Yang,Minghui Wang,Weizheng Shen,Xiaowei Teng,Jinhui Dong 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.7

Currently, TM images has a very high practical value and widely used in all aspects of agricultural. Unmanned Aerial Vehicles (UAV) remote sensing platform mounted ADC-Lite multi-spectral sensor has consistent channels response functions with TM sensor in TM2, TM3 and TM4, demonstrated to compete with TM sensor, due to low operational cost, high operational flexibility, high spatial resolution of imagery (0.018m with flight altitude 50m) and heterogeneity both at time and spatial-scale. In order to make sure whether it has widely used as TM sensor, moreover, the aim of this work is to assess ADC-Lite performance such as its adaptability and practicability. In this paper, ADC-Lite multi-spectral data, ground truth ASD hyperspectral and Leaf area index (LAI) data were acquired in soybean planting area, Jiaxiang County, Shandong Province on September18th, 2015. Since the ADC-Lite has different spatial scales with TM, this paper used TM simulation data transformed by ground truth ASD data, constructed LAI inversion model by empirical model based on two sensors and ground measured data, using 5 vegetation indices: ratio vegetation index (RVI), normalized difference vegetation index (NDVI), soil adjust vegetation index (SAVI), difference vegetation index (DVI) and triangular vegetation index (TVI). Determination coefficient R2, root mean square error (RMSE) and the estimation accuracy (EA) 3 indicators were acquired to assess the model. This work suggests that the established model of ADC-Lite sensor with TM simulation sensor has high consistency in accuracy. NDVI linear regression model derived from both of them presented a strong correlation with ground-measured LAI. It’s preliminarily shown that ADC-Lite images assess soybean LAI is feasible. This is anticipated to have tremendous implications that ADC-Lite can be made supplement for existing satellites, aerial and ground sensing, provide important information for Crop condition monitoring and critical data to support crop maturity, nutrition monitoring and fertilization management.

A Smart Strategy for Speculative Execution Based on Hardware Resource in a Heterogeneous Distributed Environment

Qi Liu,Weidong Cai,Zhangjie Fu,Jian Shen,Nigel Linge 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.2

MapReduce, as a popular programming model for processing large data sets, has been widely applied. MapReduce 2.0 (MRV2) is a newly adopted one, which has a better performance. Those machines which have a lower performance in a cluster usually play a role who pull down the pace of job execution time. Speculative execution known as an approach for dealing with the above problems works by backing up those tasks running on a low performance machine to a higher one. Although multiple speculative execution strategies have been proposed, there are still a lot of pitfalls existing in the strategies. In this paper, Some pitfalls in proposed strategy have been modified and computer hardware has been taken into consideration (HWC-Speculation). In Hadoop-2.6, we have implemented it, called Hadoop-HWC. Experiment results show that our method can find a slow task correctly, also, the performance of MRV2 is improved.

Impact of a Dust Storm on Characteristics of Particle Matter (PM) in Guangzhou, China

Qi Fan,Chong Shen,Xuemei Wang,Yuan Li,Wei Huang,Guixiong Liang,Shaoyi Wang,Zhuoer Huang 한국기상학회 2013 Asia-Pacific Journal of Atmospheric Sciences Vol.49 No.1

A strong dust-storm (23-25 April, 2009) occurred in the provinces of Inner Mongolia, Gansu, and Shanxi, North China. Cities along the storm path (from north to south: Xi’ning, Lanzhou,Chengdu, Changsha, and Guangzhou) all experienced a sharp increase in particle matter (PM10) concentration. This is the first case that an Asian dust storm hit Guangzhou in Southern China. The impacts of dust storm on the characteristics of PM were investigated using samples collected in Guangzhou during 27-29 April, 2009. In addition, the mass concentration and chemical composition during a normal non-dust period (12-14 May, 2009) were compared with those in dust period. The results show that the concentration of PM10during the dust episode (0.231 mg m−3) was twice higher than that in the non-dust episode (0.103 mg m−3). Chemical analysis showed that concentrations of metal elements, enrichment factors of metal elements, and soluble ions during the dust episode were very different from those of non-dust. The total concentration of metal elements content in PM10 was 53.5 μg m−3 in the dust episode, which is about two times higher than that in non-dust episode (28.5 μgm−3). Increases in concentrations of Na, Ti, Zn, Cu, and Cr ranged from zero to 100% during the dust episode. However, the enrichment factors in non-dust episode were higher than that in dust-storm period,indicating that the above five chemicals originated mainly from local sources in Guangzhou. The concentrations of K, Mg, Al, Fe, Mn, V,and Co increased by over 100% in the dust episode, indicating their origins of remote sources. In the dust period, some water-soluble ions increased in PM10, but the main components in PM10 were SO42−,NO3− and NH4+. At last, we assessed the sources of dusts by analyzing synoptic situation and back trajectories of air mass in Guangzhou, and demonstrated that the main source of the dust storm was from Mongolia.

The Mechanism of Rockbolt in the Jointed Rock Under Uniaxial Tension

Shen Zhou,Xiaoyu Ji,Li-Ping Li,Hong-liang Liu,Chun Zhu,Hongyun Fan,Qi Zhang,Caihua Shi,Xutong Zhang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.11

In this research, the rockbolt mechanism of a jointed rock mass under uniaxial tension was systematically revealed with a laboratory test and a numerical simulation. It was found that the rockbolt rock mass experienced five stages under uniaxial tension, the densification stage, elastic stage, plastic deformation stage, progressive debonding stage, and complete debonding stage. The stress-strain curve and ultimate tensile strength of a rockbolt rock mass were analyzed by taking the rockbolt spacing and rockbolt angle as variables. It was found that the improvement effect of the reduction of the rockbolt spacing on the ultimate tensile strength was limited. When the rockbolt spacing was reduced to a certain limit, the stress concentration area between adjacent rockbolts was connected and destroyed, resulting in the increase of the rockbolt rock strength becoming smaller, and even having a downward trend. The increase of the rockbolt angle led to the change of the stress mode and failure mode of the whole structure, and the ultimate tensile strength first increased and then decreased. The optimal rockbolt angle was between 60° and 70°. It is worth noting that there was an obvious mechanical occlusion between the thread on the rockbolt surface and the rock mass, resulting in the multi-stage step-down characteristic of the stress-strain curve in the complete debonding stage. The results of this study can provide a reference for the design and construction of similar projects.