Up-Conversion Nanoparticles/PMMA Composites for Light-Emitting Applications

Yongling Zhang,Peng Lv,Xiang Liu,Haoyuan Chi,Guoqing Xi,Zhengkun Qin 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.03

In this paper, we prepared KMnF3:Yb3+, Er3+ nanoparticles (NPs)/polymethyl methacrylate (PMMA) composites, NaYF4:Yb3+, Tm3+NPs/PMMA composites and NaYF4Yb3+, Er3+NPs/PMMA composites by in situ polymerization, and these NPs/PMMA composites can emit red, blue and green up-conversion fluorescence excited by 980nm, respectively. The mixed white NPs/PMMA composites were obtained by adjusting the doping ratio of the above three NPs. These NPs/PMMA composites are transparent. We tested the up-conversion fluorescence spectra of all the NPs and NPs/PMMA composites, under 980 nm excitation. The up-conversion luminescence spectra of the NPs and NPs/PMMA composites are consistent, which further indicates that the in situ polymerization has not changed the chemical structure of the NPs. Then, we prepared transparent bulk polymers by curing these NPs/PMMA composites. Under 980 nm laser excitation, these NPs/PMMA bulk polymers can emit red, blue, green and white up-conversion emissions, respectively. The results indicate that the NPs/PMMA composites can be applied to three-dimensional (3D) display.

FABRICATION OF SQUARAINE DYE SENSITIZED SPHERICAL ZINC OXIDE NANOCOMPOSITES AND THEIR VISIBLE-LIGHT INDUCED PHOTOCATALYTIC ACTIVITY

YONGLING FANG,SONG XU,ZHONGYU LI,DANAN HAN,DAYONG LU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.3

A 1,3-bis[(3,3-dimethylindolin-2-ylidene)methyl]squaraine (ISQ) dye sensitized ZnO nanocompo-sites via two di®erent preparation methods including hydrothermal and ultrasonic sensitizationprocesses are discussed in this paper. The as-prepared composites were characterized by the X-raydi®raction (XRD), UV-Vis di®use re°ectance spectroscopy (DRS), Raman spectroscopy, andtransmission electron microscopy (TEM). Based on the XRD patterns and TEM images, the ISQ/ZnO nanocomposites still kept the characteristic peaks and the basic morphology of ZnO and ISQdye. The photocatalytic activity of ISQ/ZnO nanocomposites was investigated by degradingmethylene blue (MB) under visible-light illumination. Compared with the MB self-degradation rate,the photocatalytic activity of the ISQ/ZnO composites was enhanced remarkably. The ISQ/ZnOnanocomposites fabricated by ultrasonic sensitization method exhibited excellent photocatalyticdegradation rate, approximately 20% higher than that of the hydrothermal sensitization one.

Spatial structure of Beijing during suburbanization

Yao Yongling 서울시립대학교 도시과학연구원 2011 도시과학국제저널 Vol.15 No.2

Urban sprawl has been a general problem for metropolitan areas, which has resulted from over suburbanization. Different spatial structures need different smart growth approaches. The more complicated spatial structure of the city than the duality structure model of core-periphery relations within China and some developing countries challenged smart growth for them. The author of this paper provided the background description, population distribution and especially the special zone of fringe areas in Beijing to describe the spatial structure of Beijing during suburbanization. The author thought in conclusion that the spatial structure of Beijing could upgrade the core-periphery model and could explain the suburbanization process more accurately than the core-periphery structure. With this model, smart growth could be more significantly practical.

Alteration of Economic Freedom during the Staging of the 29th Olympic Games in Beijing

Yao Yongling,Zhang Ruo 서울시립대학교 도시과학연구원 2008 도시과학국제저널 Vol.12 No.2

The impact of staging the Olympic Games on economic freedom is the main legacy that the Olympics might leave for the host city. It depends on the structure a city needs for further development which can be provided through the staging of the Olympics. In the case of Beijing, staging the Olympic Games can be analyzed as an important part of urban development strategy, to achieve its ambitions in marketization and globalization. The authors of this paper conducted ex-post estimation research on the impact of the preparation period of the Olympic Games. The ‘trend extrapolation’ method was adopted to roughly reconstruct the ‘baseline scenario’ and the ‘event scenario,’ in order to measure its impact on the degree of economic freedom in Beijing by comparing the indicators between these two scenarios. The conclusion explains how the Olympics markedly promoted the internationalization process of Beijing. The impact of staging the Olympic Games on economic freedom is the main legacy that the Olympics might leave for the host city. It depends on the structure a city needs for further development which can be provided through the staging of the Olympics. In the case of Beijing, staging the Olympic Games can be analyzed as an important part of urban development strategy, to achieve its ambitions in marketization and globalization. The authors of this paper conducted ex-post estimation research on the impact of the preparation period of the Olympic Games. The ‘trend extrapolation’ method was adopted to roughly reconstruct the ‘baseline scenario’ and the ‘event scenario,’ in order to measure its impact on the degree of economic freedom in Beijing by comparing the indicators between these two scenarios. The conclusion explains how the Olympics markedly promoted the internationalization process of Beijing.

Empirical Analysis of Spatial Mismatch of Living-Working: Based on a Field Survey in Downtown Beijing

Yao Yongling,Zheng Guonan 서울시립대학교 도시과학연구원 2009 도시과학국제저널 Vol.13 No.1

Spatial enlarging is the result of urban development. Owing to different motivations, migration trends during urban spatial enlarging between developed and developing countries are quiet different. The authors of this paper will take a sample of the working population in Beijing and use a survey, Geographical Information System (GIS) and statistic methods to analyze spatial disparity, in order to display the approach of urban spatial enlarging. The survey demonstrates that the downtown area is still a combination of living and working places. The conclusion is that the motivation for migration comes from the force of construction in urban areas rather than from good dwelling environments in suburbs. This is the main reason of urban problems during spatial enlarging.

Detection of Breathing Rates in Through-wall UWB Radar Utilizing JTFA

( Xiaolin Liang ),( Yongling Jiang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.11

Through-wall ultra-wide band (UWB) radar has been considered as one of the preferred and non-contact technologies for the targets detection owing to the better time resolution and stronger penetration. The high time resolution is a result of a larger of bandwidth of the employed UWB pulses from the radar system, which is a useful tool to separate multiple targets in complex environment. The article emphasised on human subject localization and detection. Human subject usually can be detected via extracting the weak respiratory signals of human subjects remotely. Meanwhile, the range between the detection object and radar is also acquired from the 2D range-frequency matrix. However, it is a challenging task to extract human respiratory signals owing to the low signal to clutter ratio. To improve the feasibility of human respiratory signals detection, a new method is developed via analysing the standard deviation based kurtosis of the collected pulses, which are modulated by human respiratory movements in slow time. The range between radar and the detection target is estimated using joint time-frequency analysis (JTFA) of the analysed characteristics, which provides a novel preliminary signature for life detection. The breathing rates are obtained using the proposed accumulation method in time and frequency domain, respectively. The proposed method is validated and proved numerically and experimentally.

The discovery of potent immunostimulatory CpG-ODNs widely distributed in bacterial genomes

Juan Liu,Yan Wei,Yongling Lu,Yangyuling Li,Qian Chen,Yan Li 한국미생물학회 2020 The journal of microbiology Vol.58 No.2

Oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG-ODN) can be specifically recognized by Toll-like receptor 9 (TLR9), provoking innate immune responses. Designed according to this structural feature, many synthetic phosphorothioate CpG-ODNs successfully activate macrophages. However, it is difficult to find potent stimulatory CpG-DNA fragments in microbial genomes. Therefore, whether microbial CpG-DNA substantially contributes to infectious and immune diseases remains controversial. In this study, high-throughput scanning was carried out for thousands of bacterial genomes with bioinformatics tools to comprehensively evaluate the distribution of CpG-DNA fragments. A random sampling test was then performed to verify their immunostimulatory properties by experiments in vitro and in vivo. Natural TLR9-dependent and potent stimulatory CpG-DNA fragments were found in microbial genomes. Interestingly, highly conserved stimulatory CpG-DNA fragments were found in 16S and 23S rDNA sequences with multiple copies, while others were species-specific. Additionally, we found that the reported active motifs were mostly nonstimulatory in natural CpG fragments. This evidence indicates that the previous structural descriptions of functional CpG-ODNs are incomplete. Our study has assessed the distribution of microbial CpG-DNA fragments, and identified natural stimulatory CpG-DNA fragments. These findings provide a deeper understanding of CpG-ODN structures and new evidence for microbial DNA inflammatory function and pathogenicity.

Characterization and functional analysis of a MYB gene (GbMYBFL) related to flavonoid accumulation in Ginkgo biloba

Weiwei Zhang,Feng Xu,Shuiyuan Cheng,Yongling Liao 한국유전학회 2018 Genes & Genomics Vol.40 No.1

Flavonoids are a group of metabolites in Ginkgo biloba thought to provide health benefits. R2R3-MYB transcription factors (TFs) play key roles in the transcriptional regulation of the flavonoid biosynthesis in plants. In this study, an R2R3-MYB transcription factor gene, GbMYBFL, was isolated from G. biloba and characterized. Results of bioinformatic analysis indicated that GbMYBFL is more closely related to the R2R3-MYB involved in flavonoid biosynthesis and displayed high similarity to MYB from other plants. The genmomic sequence of GbMYBFL had three exons and two introns, with its upstream sequence containing cis-acting regulatory elements Myb binding site, Myc recognition sites, and light, SA, MeJA responsive elements. Subcellular localization analysis indicates that GbMYBFL was located in the nucleus. Quantitative realtime PCR revealed that GbMYBFL was expressed in leaves, stems, roots, young fruits, male flower and female flower, and the level of transcription in male flower and leaves were higher than that in female flower, stems, roots, and young fruits. During G. biloba leaf growth, the transcription of GbMYBFL is positively correlated with the flavonoid content, suggesting that the GbMYBFL is involved in the flavonoid biosynthesis. Overexpression of GbMYBFL under the control of the CaMV35S promoter in Ginkgo callus notably enhanced the accumulation of flavonoids and anthocyanin compared with non-transformed callus. This finding suggested that GbMYBFL positively related to flavonoid biosynthesis, and the overexpression of GbMYBFL was sufficient to induce flavonoids and anthocyanin accumulation.

Investigation of interface properties in oxide passivated boron diffused silicon

Natalita M. Nursam,Klaus J. Weber,Hao Jin,Yongling Ren 한국물리학회 2010 Current Applied Physics Vol.10 No.3

Electron paramagnetic resonance (EPR) measurements were employed to observe the dominant defect at the thermally grown (1 1 1) Si–SiO2 interface, namely the Pb center, of samples with oxides grown at moderate temperatures. The presence of boron diffusion leads to an increase of the Pb density by a factor of ~1.6 to 1.8, significantly less than previously reported for higher temperature oxides. The Pb density for samples with similar emitter sheet resistances but different (by a factor of 4) boron surface concentrations were similar, suggesting that the increase in Pb concentration following is primarily determined by the total boron dose. Investigations of the stability of the passivation of boron diffused, oxide passivation emitters strongly suggest that degradation is the result of the permeability of SiO2 to moisture,which can be prevented through the addition of a moisture barrier.

Wind-tunnel study of wake galloping of parallel cables on cable-stayed bridges and its suppression

Yongle Li,Mengxue Wu,Xinzhong Chen,Tao Wang,Haili Liao 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.3

Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.