Feasibility of Using a One-temperature Model for Determining Plasma’s Temperature by Measuring Its Refractive Index

Yun-yun Chen,Fen-ping Cui,Fang Gu,Ying-ying Zhang 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.11

In this paper, the feasibility of using a one-temperature model to determine plasma’s temperatureby measuring its refractive index is studied based on the consideration that many plasma flow fieldsare not in local thermodynamic equilibrium (LTE). We compare the refractive indices between theone- and the two-temperature models of an arc plasma, in order to discuss the applicability ofthe one-temperature model in optical diagnosis. We found that the applicability is determined bythe pressure, the temperature ratio between electrons and heavy particles, the probe wavelength,and the chosen optical method’s refractive index measurement precision. Consequently, a commonmodel is deduced to describe the refractive index of plasma whether it be in LTE or not. In a word,this study is crucial to better apply optical methods based on measurements of the refractive indexto diagnose plasma flow fields.

Effect of under-bump-metallization structure on electromigration of Sn-Ag solder joints

Chen, Hsiao-Yun,Ku, Min-Feng,Chen, Chih Techno-Press 2012 Advances in materials research Vol.1 No.1

The effect of under-bump-metallization (UBM) on electromigration was investigated at temperatures ranging from $135^{\circ}C$ to $165^{\circ}C$. The UBM structures were examined: 5-${\mu}m$-Cu/3-${\mu}m$-Ni and $5{\mu}m$ Cu. Experimental results show that the solder joint with the Cu/Ni UBM has a longer electromigration lifetime than the solder joint with the Cu UBM. Three important parameters were analyzed to explain the difference in failure time, including maximum current density, hot-spot temperature, and electromigration activation energy. The simulation and experimental results illustrate that the addition 3-${\mu}m$-Ni layer is able to reduce the maximum current density and hot-spot temperature in solder, resulting in a longer electromigration lifetime. In addition, the Ni layer changes the electromigration failure mode. With the $5{\mu}m$ Cu UBM, dissolution of Cu layer and formation of $Cu_6Sn_5$ intermetallic compounds are responsible for the electromigration failure in the joint. Yet, the failure mode changes to void formation in the interface of $Ni_3Sn_4$ and the solder for the joint with the Cu/Ni UBM. The measured activation energy is 0.85 eV and 1.06 eV for the joint with the Cu/Ni and the Cu UBM, respectively.

Two New Lignans from the Bark of Zanthoxylum planispinum Yun Hu,

Yun Hu,Yu Chen,Yue Shang,Guangzhong Yang 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.8

Electro-active paper for a durable biomimetic actuator

Yun, Sung-Ryul,Yun, Gyu Young,Kim, Jung Hwan,Chen, Yi,Kim, Jaehwan Institute of Physics Publishing 2009 Smart materials & structures Vol.18 No.2

<P>Cellulose electro-active paper (EAPap), known as a smart material, has merits in terms of low voltage operation, light weight, dryness, low power consumption, biodegradability, abundance and low price. Since EAPap requires low power consumption, a remotely driven actuator has been proposed using microwave power transmission. This concept is attractive for many biomimetic systems such as crawling micro-insect robots, flying objects like dragon flies and smart wallpapers. However, the actuation performance of EAPap is sensitive to humidity and degrades with time. Thus, in this paper, a durable EAPap is studied. The fabrication of EAPap is explained and the actuation performance is shown with applied electric field, frequency, humidity level and time. The fabrication process includes dissolving cellulose fibers, eliminating solvent and Li ions with a mixture of deionized water and isopropyl alcohol, washing with water, drying and coating with gold. The morphology of the fabricated EAPap is analyzed by taking scanning electron microscope images and x-ray diffractograms. The actuation performance is tested in terms of bending displacement with frequency, time and humidity level </P>

[Poster Presentation] NOT ALL PAC IS SUITABLE

Chen Yun-Zhi,Xie Lai-Su 한국펄프·종이공학회 1999 한국펄프종이학회 기타 간행물 Vol.- No.-

In this paper, a series of PAC (polyaluminum chloride) samples were prepared for rosin neutral sizing system. Some characters of PAC were discussed in detail. The experimental results show that it is possible to achieve neutral sizing when PAC is compounded with DRS(dispersed rosin size)instead of alum (aluminum sulfate).

Stability Analysis for Time-delay Systems via a Novel Negative Condition of the Quadratic Polynomial Function

Yun Chen,Yaqi Li 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.9

This paper studies the stability analysis problem for time-varying delay systems. An appropriate Lyapunov-Krasovskii functional (LKF) is constructed where its derivative is a quadratic polynomial function of the delay. A novel negative condition of the mentioned quadratic function with two variable parameters is developed to ensure that the LKF derivative is negative, reducing conservatism on some similar results. Besides, an extended version of Bessel-Legendre inequality is introduced to be employed in the stability analysis of time-varying delay systems. Then, some stability criteria with less conservatism are derived for two kinds of the time-varying delay. Finally, the effectiveness of the proposed stability criteria is demonstrated through three examples.

Synthesis and characterization of bis(2,2-dinitropropyl ethylene) formal plasticizer for energetic binders

Yun Chen,Jin Seuk Kim,권영환 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.3

A novel gem-dinitro bis(2,2-dinitropropyl ethylene) formal (BDNPEF) was synthesized and its potential application to plasticize energetic binders was investigated. BDNPEF was synthesized from aldol condensation of formaldehyde with 2,2-dinitropropanol (DNP-OH) and ethylene glycol (EG), followed by purification. One of the byproducts of this process was bis(2,2-dinitropropyl) formal (BDNPF), which is currently used as an energetic plasticizer. Compared to commercial nitro plasticizers, BDNPEF synthesized in this study showed good plasticization efficiency with a decrease in glass transition temperature (Tg) and viscosity of uncured glycidyl azide polymer (GAP) blends, as well as substantial ability to plasticize the GAP-based polyurethanes (PUs). BDNPEF has potential applications as an energetic plasticizer to engineer the properties of the GAP-based energetic PU binders.

Large-scale dataset from China gives new insights into leaf margin-temperature relationships

Chen, Wen-Yun,Su, Tao,Adams, Jonathan M.,Jacques, Fré,dé,ric M.B.,Ferguson, David K.,Zhou, Zhe-Kun Elsevier 2014 Palaeogeography, palaeoclimatology, palaeoecology Vol.402 No.-

Leaf margin analysis (LMA) is an important method of estimating paleotemperatures from fossil leaf floras or modern floras. Although some calibration has been carried out based upon large-scale studies of modern forests, most of this research has been in North America and Europe, with relatively little calibration work in East Asia. In the present study, we used species range maps of 3116 native dicot trees of China to derive synthetic local floras for each county from the Chinese humid region, and compared the percentage of untoothed leaf margined species with several temperature and precipitation related parameters. The results confirm the generally strong relationship between the proportion of species with untoothed leaf margins and climatic parameters within China. Leaf habit (deciduous vs. evergreen) does not strongly affect this relationship. The transfer function obtained from China, while not identical, is similar to those obtained from other regions, and is affected by regional restrictions, such as complex topography and relic taxa. As such it clarifies the potential range of error inherent in the LMA method as applied to paleodimate reconstruction. It is possible, however, that with the close similarity of the modern Chinese tree floras to Neogene floras in the Northern Hemisphere, the present estimate offers a better transfer function for reconstructing the Neogene paleoclimate in various regions without extremely cold conditions across the Northern Hemisphere. (C) 2014 Published by Elsevier B.V.

Detoxification, antioxidant, and digestive enzyme activities and gene expression analysis of Lymantria dispar larvae under carvacrol

Chen Yun-ze,Zhang Bo-wen,Yang Jing,Zou Chuan-shan,Li Tao,Zhang Guo-cai,Chen Guang-sheng 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.1

Carvacrol is a terpene compound with various biological activities. However, few studies have specifically focused on its insecticidal activity and mechanism of carvacrol. The larvae of Lymantria dispar are seriously harmful herbivorous insect. This study measured the antifeedant, growth-inhibitory, and toxic effects of carvacrol on L. dispar larvae. To further clarify the insecticidal mechanism of carvacrol, the effects of carvacrol on detoxifying enzymes, antioxidative enzymes, digestive enzyme activities, and the mRNA expression of the abovementioned enzyme genes were investigated. The results of the study showed that the median lethal concentration (LC 50 ) and the sublethal concentration (LC 20 ) of carvacrol were 1.120 mg/mL and 0.297 mg/mL, respectively, at 72 h. After LC 20 treatment of L. dispar larvae for 72 h, food intake and weight gain were significantly lower compared with the control. Enzyme activity assays showed that carvacrol significantly inhibited the activities of carboxylesterase (CarE), glutathione S-transferase (GST), and acetylcholinesterase (AchE), and the inhibition rate of AchE activity was highest (66.51%). Carvacrol also activated the activities of superoxide dismutase (SOD) and catalase (CAT), while it inhibited the activities of lipase (LIP) and amylase (AMS), and first inhibited and then activated protease. In addition, qRT-PCR tests showed that carvacrol affected the mRNA expression levels of CarE, GST, AchE, SOD, CAT, LIP, AMS, and protease. This study helps to clarify the insecticidal mechanism of carvacrol on L. dispar larvae.

Nitric Oxide Synthase 3 Gene Variants and Colorectal Cancer: a Meta-Analysis

Chen, Yang,Li, Jie,Guo, Yun,Guo, Xiao-Yun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.8

Background: Colorectal cancer (CRC) is the worldwide disease which causes enormous losses every year. Recent studies suggested that environmental and gene factors might be the etiologies in increasing the risk of morbidity. Nitric oxide synthase 3 (NOS3) gene polymorphisms are said to be associated with CRC risk but the conclusion is still controversial. Materials and Methods: Pubmed and HuGENet databases up to December 2013 were used in this meta-analysis. Three different certain genotypic models were applied, namely dominant (AA+AC versus CC), recessive (AA versus AC+CC), per-allele analysis (A vs C). In addition, information on tumor sites and pathologic stages was collected. The strength of associations was assessed through combining odds ratio (OR) and 95% confidence interval (CI). Results: Finally, five and three studies about the rs1799983 and rs2070744 were covered in the analysis with 2,745 cases and 2,478 controls. Three models were applied, but no significant association was found for NOS3 G894T/rs1799983 (dominant: OR=0.999, 95%CI=0.797-1.253, $I^2$=63.8%; recessive: OR=0.924, 95%CI=0.589-1.450, $I^2$=59.3%; allele analysis: OR=0.979, 95%CI=0.788-1.216, $I^2$=74.9%) and T-786C/rs2070744 (dominant: OR=1.138, 95%CI=0.846-1.530, $I^2$=67.9%; recessive: OR=0.956, 95%CI=0.708-1.291, $I^2$=0.0%; allele analysis: OR=1.110, 95%CI=0.865-1.425, $I^2$=69.4%). The same results were also obtained for tumor sites and pathologic stage subgroups. After further analyzing the NOS3 gene, rs1799983 as the tag- and functional SNP was presented. Conclusions: On the basis of this meta-analysis and the characteristics of the NOS3 gene, we suggested rs1799983 might be a key locus associated with CRC risk. Further prospective studies were needed to make more comprehensive explanation of the associations.