Effect of the TiO2 Nanoparticles on the Growth Behavior of Intermetallics in Sn/Cu Solder Joints

Shengyan Shang,Anil Kunwar,Jinye Yao,Yanfeng Wang,Haitao Ma,Yunpeng Wang 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2

In order to investigate the effect of TiO2 nanoparticles on growth behavior of interfacial Cu6Sn5 intermetallics compounds(IMCs) in Pb-free Sn/Cu system, the solder joints are fabricated by using flux doped with different content (0.0–2.0 wt% offlux) and particle diameter (5 nm and 50 nm) of TiO2 . In context of isothermal reflow soldering at 250 °C and subsequentair cooling, the increase in reflow duration from 10 to 120 s was characterized with an increment in IMC layer thicknessand grain size, due to the enhancement of Cu flux contribution for Ostwald ripening during constant temperature reflow andprecipitation kinetics during cooling. The increased proportion of TiO2 nanoparticles in flux was found to reduce the growthof IMC layer and grain size. The suppression effect on IMC was more pronounced for 5 nm particles as compared to the 50nm TiO2 . The TiO2 nanoparticles, adsorbed on IMC plane can retard the growth of the latter. Presence of sufficient amountof a given sized TiO2 nanoparticles among IMCs, by increasing the effective stress at the localized interfaces, and causingthe breaking of brittle Cu6Sn5 during growth stage; can help in the inhibition of IMC whisker formation. Particle diameterand mass proportion of TiO2 nanoparticles are important for soldering materials design.

Upregulation of MicroRNA-34a Sensitizes Ovarian Cancer Cells to Resveratrol by Targeting Bcl-2

Shangli Yao,Ming Gao,Zujun Wang,Wenyan Wang,Lei Zhan,Bing Wei 연세대학교의과대학 2021 Yonsei medical journal Vol.62 No.8

Purpose: Resveratrol (REV), a natural compound found in red wine, exhibits antitumor activity in various cancers, includingovarian cancer (OC). However, its potential anti-tumor mechanisms in OC are not well characterized. Here, we tried to elucidatethe underlying mechanisms of REV in OC cells. Materials and Methods: The anti-proliferative effects of REV against OC cells were measured using CCK-8 assay. Apoptosis wasmeasured using an Annexin V-FITC/PI apoptosis detection kit. The anti-metastasis effects of REV were evaluated by invasion assayand wound healing assay. The miRNA profiles in REV-treated cells were determined by microarray assay. Results: Our results showed that REV treatment suppresses the proliferation, induces the apoptosis, and inhibits the invasion andmigration of OV-90 and SKOV-3 cells. miR-34a was selected for further study due to its tumor suppressive roles in various humancancers. We found miR-34a overexpression enhanced the inhibitory effects of REV on OC cells, whereas miR-34a inhibition hadthe opposite effect in OC cells. In addition, we verified that BCL2, an anti-apoptotic gene, was found directly targeted by miR-34a. We also found that REV reduced the expression of Bcl-2 in OC cells. Further investigations revealed that overexpression of Bcl-2significantly abolished the anti-tumor effects of REV on OC cells. Conclusion: Overall, these results demonstrated that REV exerts anti-cancer effects on OC cells through an miR-34a/Bcl-2 axis,highlighting the therapeutic potential of REV for treatment of OC.

An Energy Efficient Localized Topology Control Algorithm for Wireless Multihop Networks

Shang, Dezhong,Zhang, Baoxian,Yao, Zheng,Li, Cheng The Korea Institute of Information and Commucation 2014 Journal of communications and networks Vol.16 No.4

Localized topology control is attractive for obtaining reduced network graphs with desirable features such as sparser connectivity and reduced transmit powers. In this paper, we focus on studying how to prolong network lifetime in the context of localized topology control for wireless multi-hop networks. For this purpose, we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hop neighborhood topology. In order to achieve long network lifetime, we introduce a new metric for characterizing the energy criticality status of each link in the network. Each node independently builds a local energy-efficient spanning tree for finding a reduced neighbor set while maximally avoiding using energy-critical links in its neighborhood for the local spanning tree construction. We present the detailed design description of our algorithm. The computational complexity of the proposed algorithm is deduced to be O(mlog n), where m and n represent the number of links and nodes in a node's one-hop neighborhood, respectively. Simulation results show that our algorithm significantly outperforms existing work in terms of network lifetime.

Factors Influencing Users’ Word-of-Mouth Intention Regarding Mobile Apps : An Empirical Study

Yao Chen,Yu-Fei Shang 한국유통과학회 2018 The Journal of Industrial Distribution & Business( Vol.9 No.1

Purpose - This paper aims to identify factors that influence the users' word-of-mouth intention (WOMI) regarding mobile apps, focussing on the impacts of technology acceptance model (TAM) and social network theory. Research design, data and methodology - Based on TAM, this study integrates social network theory into the research model. The 317 sets of data collected in a survey were tested against the model using SmartPLS. Results - Our findings suggest the following: 1) Personal innovativeness positively influences perceived usefulness (PU), perceived ease of use (PEU) and perceived enjoyment (PE); 2) PEU affects PU and PE; 3) Both PU and Satisfaction are directly correlated with WOMI. Although PEU and PE has no direct impact on WOMI, they may indirectly affect WOMI via Satisfaction, as PU, PEU and PE all positively influence satisfaction; 4) Network density and network centrality both play a mediating role in the relation between PEU and WOMI. Referral Reward Program have a positive moderating effect on the relation between PU and WOMI. Conclusions - The findings of this study illustrate the traits of Apps that can promote users’ WOMI, as well as the characteristics of people who are more likely to participate in the word-of-mouth process. The findings provide a theoretical basis for app developers to make word-of-mouth a marketing strategy.

Modeling, Identification and Control of a Redundant Planar 2-DOF Parallel Manipulator

Yao-Xin Zhang,Shuang Cong,Wei-Wei Shang,Ze-Xiang Li,Shi-Long Jiang 대한전기학회 2007 International Journal of Control, Automation, and Vol.5 No.5

In this paper, the dynamic controller design problem of a redundant planar 2-dof parallel manipulator is studied. Using the Euler-Lagrange equation, we formulate the dynamic model of the parallel manipulator in the joint space and propose an augmented PD controller with forward dynamic compensation for the parallel manipulator. By formulating the controller in the joint space, we eliminate the complex computation of the Jacobian matrix of joint angles with end-effector coordinate. So with less computation, our controller is easier to implement, and a shorter sampling period can be achieved, which makes the controller more suitable for high-speed motion control. Furthermore, with the combination of static friction model and viscous friction model, the active joint friction of the parallel manipulator is studied and compensated in the controller. Based on the dynamic parameters of the parallel manipulator evaluated by direct measurement and identification, motion control experiments are implemented. With the experiments, the validity of the dynamic model is proved and the performance of the controller is evaluated. Experiment results show that, with forward dynamic compensation, the augmented PD controller can improve the tracking performance of the parallel manipulator over the simple PD controller.

Geometrical Effects of Cu@Ag Core–Shell Nanoparticles Treated Flux on the Growth Behaviour of Intermetallics in Sn/Cu Solder Joints

Shengyan Shang,Anil Kunwar,Yanfeng Wang,Jinye Yao,Yingchao Wu,Haitao Ma,Yunpeng Wang 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.2

Solder ball of initial diameter 1.4 mm, was refl ow soldered with Cu substrate at 523.15 K using fl ux doped with Cu@Agcore–shell nanoparticles (NPs) in the proportion 0–2 wt%. The solders were then air cooled to room temperature. The use ofNPs, by reducing the base height (H) of the solder and enhanced the diameter (W) of the solder, caused an overall increase inthe spread ratio of the solder. The altered magnitudes of heat and mass transfer in these geometrically diff erent but constantvolume specimens were analyzed using fi nite element method. The occurrence of diff erential concentration gradient, radialthermal gradient and velocity magnitudes, in solders with diff ering geometry were numerically elaborated. The Cu6Sn5 intermetalliccompound (IMC) formed at the Cu/Sn interface, was obtained to be the thickest for the specimen using undopedfl ux, whereas it was found to be smallest for the sample processed with fl ux containing 0.5% NPs. From the growth kineticsstudy, it has been inferred that IMC thickness is linearly proportional to the geometrical parameter H and Wb , with b < 1.

An Energy Efficient Localized Topology Control Algorithm for Wireless Multihop Networks

Dezhong Shang,Baoxian Zhang,Zheng Yao,Cheng Li 한국통신학회 2014 Journal of communications and networks Vol.16 No.4

Localized topology control is attractive for obtaining reducednetwork graphs with desirable features such as sparser connectivityand reduced transmit powers. In this paper, we focus onstudying how to prolong network lifetime in the context of localizedtopology control for wireless multi-hop networks. For this purpose,we propose an energy efficient localized topology control algorithm. In our algorithm, each node is required to maintain its one-hopneighborhood topology. In order to achieve long network lifetime,we introduce a new metric for characterizing the energy criticalitystatus of each link in the network. Each node independentlybuilds a local energy-efficient spanning tree for finding a reducedneighbor set while maximally avoiding using energy-critical linksin its neighborhood for the local spanning tree construction. Wepresent the detailed design description of our algorithm. The computationalcomplexity of the proposed algorithm is deduced to beO(mlog n), where m and n represent the number of links andnodes in a node’s one-hop neighborhood, respectively. Simulationresults show that our algorithm significantly outperforms existingwork in terms of network lifetime.

Effect of Experiential Value on Customer Satisfaction and e-WOM under O2O Commerce

Yu-Fei Shang(상옥비),Yao Chen(진요),Hong-Seop Kim(김홍섭) 한국유통과학회 2017 유통과학연구 Vol.15 No.8

Purpose - The online-to-offline (O2O) business model has brought considerable changes to the traditional Chinese business model. The main difference between O2O and pure online consumption is that O2O offers a richer experience and word-of-mouth. it is easier to trigger online word-of-mouth. However, few scholars have been concerned about the impact of experiential value on customer satisfaction and online word-of-mouth (e-WOM) in the study of O2O. This study takes the O2O business model in China’s catering industry as its research object and uses structural equation modelling to analyze the impact of online and offline experiential values on customer satisfaction and e-WOM. Research design, data, and methodology - According to previous researches, consumer experiential value is mainly divided into return on investment (economy and efficiency), service excellence, playfulness and aesthetics. According to the characteristics of O2O in China’s catering industry, this study divides the online experience value into efficiency and economy (return on investment). The offline part is divided into return on investment (economy and efficiency), service excellence, playfulness and aesthetics. Using a web-based survey, we collected 303 valid samples. Structural equation modelling was used to create the research model. Results - The results show that efficiency (online) and service excellence (offline) have a significant effect on customer satisfaction. Economics (online) and playfulness (offline) have a positive impact on customers’ e-WOM. In addition, the higher the customer satisfaction, the greater the positive impact on the spread by word of mouth. However, aesthetic(offline) and return on investment(offline) have no significant impact to customer satisfaction and e-WOM. Conclusions - The study findings show that the key to boost customer satisfaction in the catering industry is to improve product quality and service. Although traditional competitive strategies such

Involvement of MicroRNA-198 Overexpression in the Poor Prognosis of Esophageal Cancer

Qi, Bo,Yao, Wen-Jian,Zhao, Bao-Sheng,Qin, Xiu-Guang,Wang, Yi,Wang, Wen-Ju,Wang, Tian-Yun,Liu, Shang-Guo,Li, Han-Chen Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.9

Objective: This study aimed to investigate whether the miR-198 expression level is related to clinicopathological factors and prognosis of esophageal cancer. Methods: MicroRNA was extracted from esophageal cancer patients who underwent surgery for assessment using the Taqman@ MicroRNA assay. The correlation between miR-198 expression and clinicopathological features was analyzed, and the significance of miR-198 as a prognostic factor and its relationship with survival was determined. Results: MicroRNA-198 (miR-198) expression was higher in patients with poor prognosis than those with good prognosis (P<0.05). Kaplan-Meier analysis results showed that the miR-198 expression level had a significant correlation with survival time (P=0.030) and that patients with a higher expression of miR-198 had a shorter survival time. Cox multi-factor model analysis showed that patient prognosis (P=0.014), tumor length (P=0.040) and expression (P=0.012), and survival time had a significant correlation; the corresponding risks were 7.268, 1.246, and 3.524, respectively. Conclusion: miR-198 overexpression is involved in the poor prognosis of esophageal cancer and can be used as a biomarker for selection of cases requiring especial attention.

Effect of Crude Protein Levels in Concentrate and Concentrate Levels in Diet on In vitro Fermentation

Dung, Dinh Van,Shang, Weiwei,Yao, Wen Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.6

The effect of concentrate mixtures with crude protein (CP) levels 10%, 13%, 16%, and 19% and diets with roughage to concentrate ratios 80:20, 60:40, 40:60, and 20:80 (w/w) were determined on dry matter (DM) and organic matter (OM) digestibility, and fermentation metabolites using an in vitro fermentation technique. In vitro fermented attributes were measured after 4, 24, and 48 h of incubation respectively. The digestibility of DM and OM, and total volatile fatty acid (VFA) increased whereas pH decreased with the increased amount of concentrate in the diet (p<0.001), however CP levels of concentrate did not have any influence on these attributes. Gas production reduced with increased CP levels, while it increased with increasing concentrate levels. Ammonia nitrogen ($NH_3$-N) concentration and microbial CP production increased significantly (p<0.05) by increasing CP levels and with increasing concentrate levels in diet as well, however, no significant difference was found between 16% and 19% CP levels. Therefore, 16% CP in concentrate and increasing proportion of concentrate up to 80% in diet all had improved digestibility of DM and organic matter, and higher microbial protein production, with improved fermentation characteristics.