Multiband and Broadband Absorption Enhancement of Monolayer Graphene at Optical Frequencies from Multiple Magnetic Dipole Resonances in Metamaterials

Liu, Bo,Tang, Chaojun,Chen, Jing,Xie, Ningyan,Tang, Huang,Zhu, Xiaoqin,Park, Gun-sik Springer US 2018 NANOSCALE RESEARCH LETTERS Vol.13 No.1

<P>It is well known that a suspended monolayer graphene has a weak light absorption efficiency of about 2.3% at normal incidence, which is disadvantageous to some applications in optoelectronic devices. In this work, we will numerically study multiband and broadband absorption enhancement of monolayer graphene over the whole visible spectrum, due to multiple magnetic dipole resonances in metamaterials. The unit cell of the metamaterials is composed of a graphene monolayer sandwiched between four Ag nanodisks with different diameters and a SiO<SUB>2</SUB> spacer on an Ag substrate. The near-field plasmon hybridizations between individual Ag nanodisks and the Ag substrate form four independent magnetic dipole modes, which result into multiband absorption enhancement of monolayer graphene at optical frequencies. When the resonance wavelengths of the magnetic dipole modes are tuned to approach one another by changing the diameters of the Ag nanodisks, a broadband absorption enhancement can be achieved. The position of the absorption band in monolayer graphene can be also controlled by varying the thickness of the SiO<SUB>2</SUB> spacer or the distance between the Ag nanodisks. Our designed graphene light absorber may find some potential applications in optoelectronic devices, such as photodetectors.</P>

Molecular engineering of indoline based organic sensitizers for highly efficient dye-sensitized solar cells

Liu, Bo,Liu, Qingbin,You, Dan,Li, Xiaoyan,Naruta, Yoshinori,Zhu, Weihong The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.26

<P>The increasing electron-donating ability of the donor part is focused to further optimize the light-harvesting capability. Our strategy is to introduce an additional donor group into the indoline unit in the donor part to form a donor–donor structure (D–D moiety). Three different units (carbazole, fluorene and 4-methylphenyl groups) with different degrees of electron-donating capability are incorporated, thus constructing the specific donor–donor–π–acceptor (D–D–π–A) system (C-CA, F-CA and I-3) and giving a systematic view of the absorption evolution. Through molecular engineering, their light-harvesting capabilities, energy levels and photovoltaic performances were studied. As expected, utilizing strong electron-donating carbazole unit as additional donor, the IPCE spectrum of DSSC based on C-CA is successfully broadened to NIR region on the premise of suitable LUMO level, with an extraordinarily high plateau in visible region till around 700 nm. In the system of C-CA and F-CA, the introduction of <I>n</I>-pentyl group in donor part of carbazole and fluorene unit has little effect on preventing the molecular π-aggregation due to the good co-planarity of π-linker (vinyl thiophene), suggesting that the most effective way to prevent π-aggregation is still the incorporation of long alkyl groups into planar π-linker segment. However, the introducing long alkyl group can effectively prevent the electron recombination between electrons in conduction band (CB) of TiO<SUB>2</SUB> and I<SUB>3</SUB><SUP>−</SUP> ions. Along with the preferable light-harvesting capability, C-CA presents excellent IPCE performance with a short-circuit photocurrent (<I>J</I><SUB>sc</SUB>) of 18.53 mA cm<SUP>−2</SUP>, an open-circuit photovoltage (<I>V</I><SUB>oc</SUB>) of 649 mV, a fill factor of 0.71, corresponding to a power conversion efficiency (<I>η</I>) of 8.49%. The internal relations between chemical structure and conversion efficiency provide a strategy for developing highly efficient organic sensitizers working in whole visible region with high photovoltaic performance.</P> <P>Graphic Abstract</P><P>Utilizing a carbazole unit as additional donor, the photoresponse of C-CA is broadened to the NIR region with a <I>η</I> of 8.49%. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm31704d'> </P>

A method for underwater image analysis using bi-dimensional empirical mode decomposition technique

Liu, Bo,Lin, Yan Techno-Press 2012 Ocean systems engineering Vol.2 No.2

Recent developments in underwater image recognition methods have received large attention by the ocean engineering researchers. In this paper, an improved bi-dimensional empirical mode decomposition (BEMD) approach is employed to decompose the given underwater image into intrinsic mode functions (IMFs) and residual. We developed a joint algorithm based on BEMD and Canny operator to extract multi-pixel edge features at multiple scales in IMFs sub-images. So the multiple pixel edge extraction is an advantage of our approach; the other contribution of this method is the realization of the bi-dimensional sifting process, which is realized utilizing regional-based operators to detect local extreme points and constructing radial basis function for curve surface interpolation. The performance of the multi-pixel edge extraction algorithm for processing underwater image is demonstrated in the contrast experiment with both the proposed method and the phase congruency edge detection.

Cervical Cancer Gene Therapy by Gene Loaded PEG-PLA Nanomedicine

Liu, Bo,Han, Shu-Mei,Tang, Xiao-Yong,Han, Li,Li, Chang-Zhong Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12

Background and Aims: Advances in the treatment of cervical cancer over the last decade have predominantly involved the development of genes directed at molecular targets. Gene therapy is recognized to be a novel method for the treatment of cervical cancer. Genes can be administered into target cells via nanocarriers. This study aimed to develop systemically administrable nano-vectors. Floate (Fa) containing gene loaded nanoparticles (NPs) could target HeLa human cervical cancer cells through combination with receptors on the cells to increase the nuclear uptake of genetic materials. Methods: Fa was linked onto Poly (ethylene glycol)-b-poly (D, L-lactide) (PEG-PLA) to form Fa-PEG-PLA, and the resulting material was used to load plasmids of enhanced green fluorescence protein (pEGFP) to obtain gene loaded nanoparticles (Fa-NPs/DNA). Physical-chemical characteristics, in vitro release and cytotoxicity of Fa-NPs/DNA were evaluated. The in vitro transfection efficiency of Fa-NPs/DNA was evaluated in HeLa cells and human umbilical vein endothelial cells (HUVEC). PEG-PLA without Fa was used to load pEGFP from NPs/DNA as a control. Results: Fa-NPs/DNA has a particle size of 183 nm and a gene loading quantity of 92%. After 72h of transfection, Fa-NPs/DNA displayed over 20% higher transfection efficiency than NPs/DNA and 40% higher than naked DNA in HeLa cells. However, in HUVECs, no significant difference appeared between Fa-NPs/DNA and NPs/DNA. Conclusions: Fa-PEG-PLA NPs could function as excellent materials for gene loading. This nano-approach could be used as tumor cell targeted medicine for the treatment of cervical cancer.

Analysis on Slope Stability of Open Pit Coal Mine Based on Grey Support Vector Machine

Liu Bo,Zhang Peng,Zhang Jianwei 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.9

Shenhua BaoRi XiLe open-pit coal mine slope is located in the seismic belt of hulunbuir prairie in Inner Mongolia, which belongs to the high frequency and intensity earthquake zone, with rainfall concentrated, poor geological distribution, under the influence of complex environmental factors, extremely easy to cause landslide. This paper uses grey model and support vector machine (SVM) to establish slope model, and carries out stress and strain characteristics under the condition of natural, rainfall, earthquake and calculation and analysis of stability. Through the experiment, it analyzes the stability coefficient of downhill under rainfall condition, and obtains the different strength reduction of safety factor list. At the same time, give full consideration to the uncertainty of the earthquake, assume a variety of working conditions of the earthquake, it conducts dynamic analysis of the slope in detail, and gets the dynamic characteristics curves of the monitoring points. Results show that, relative complex terrain conditions, climate conditions and at a high intensity earthquakes area, are the main factors to induce landslides in this region. Therefore, this paper provides a reliable basis for further study of the effects of rainfall and earthquake on slope and disaster prevention and mitigation.

Study on the Formation Mechanism of Seismic Fracture Source of Debris Flow in Strong Seismic Area

( Liu Bo ),( Hu Xiewen ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The "5.12" Wenchuan Earthquake resulted in a large number of shattering of thin ridges. Induced by heavy rainfall, such high-level shattered mountains lose stability and damage, which will produce a large number of solid materials and significantly increase the hazards of debris flows in the earthquake area. In this paper, the formation mechanism of seismic crack source is studied by large-scale shaking table physical simulation test. Under different inclination of layers conditions, the acceleration, displacement, stress, deformation and failure characteristics of different parts of the model slope are simulated to analyze the seismic response law of thin ridges. The results show that: (1) the horizontal acceleration amplification coefficient of the model increases obviously when the height is above 3/5H from the bottom of the model, and the obvious vertical acceleration amplification effect appears at 3/4H from the bottom; (2) the acceleration response intensity of the hill body of the layered structure model is greater than that of the homogeneous structure model, and the correlation with the horizontal acceleration increases with the increase of the excitation frequency. (3) For the layered structure model, the larger the dip angle of the layer, the larger the top deformation is under the same excitation intensity; (4) For the weak interlayer model, the failure location of the horizontal interlayer model is higher than that of the inclined interlayer model, and the deformation of the thin interlayer model is larger than that of the thick interlayer model.

Pavement performance analysis of carbon nanotube/SBS composite modified asphalt

Liu Bo,Li Xiaoliang,Li Sheng 한국탄소학회 2024 Carbon Letters Vol.34 No.1

In order to prevent early distress in asphalt pavement and save on subsequent operational and maintenance costs, modifying asphalt is an effective approach. Styrene–butadiene–styrene (SBS) block copolymers, due to their excellent physicochemical properties, have become a mature and widely used asphalt modifier. Carbon nanotubes (CNTs) possess advantages such as a large specific surface area and high modulus, which, when incorporated into asphalt, can enhance its deformation resistance. To analyze the effect of incorporating CNTs on SBS-modified asphalt (SBS-A), this study analyzed the influence of different CNT concentrations on the high and low-temperature performance and aging properties of SBS-A through penetration, softening point, ductility, dynamic shear rheometry, and short-term aging tests. The optimal CNT concentration was determined to be 1.0%. Furthermore, the changes in the modified asphalt during the aging process were analyzed using infrared spectroscopy.

카 셰어링 서비스 이용 의도에 자기효능감과 정보품질이 미치는 영향

LIUBO(유파),변숙은 한국유통학회 2023 한국유통학회 학술대회 발표논문집 Vol.2023 No.4

Recent progress on two-dimensional neuromorphic devices and artificial neural network

Tian Changfa,Wei Liubo,Li Yanran,Jiang Jie 한국물리학회 2021 Current Applied Physics Vol.31 No.-

Mimicking biological synapses with microelectronic devices is widely considered as the first step in hardware building artificial neuromorphic networks, which is also the basis of brain-inspired neuromorphic computing. Numerous artificial neurons and synapses making up an artificial neuromorphic network have been gained wide attention due to their powerful and efficient data processing capabilities. Recently, artificial synapses, especially memristor-type and transistor-type synapses based on multifarious two-dimensional (2D) materials have been paid much attention. The unique properties of 2D materials make devices perform well in learning ability and power efficiency when mimicking synaptic behaviors, which highlights the feasibility of 2D neuromorphic devices in constructing artificial neuromorphic networks. Herein, the basic structures and principles of biological synapses are introduced, and the definitions of synaptic behaviors in synaptic electronic devices are discussed. Then, the progress of 2D memristor-type and transistor-type neuromorphic devices involving their device architecture, neuromorphic operational mechanism, and promising applications is reviewed. Finally, the future challenges of artificial synaptic devices based on 2D materials are discussed briefly.

Infrared Camera Calibration in the 3D Temperature Field Reconstruction

Sun Xiaoming,Wu Haibin,Wang Wei,Liubo,Cui Guoguang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.6

In order to reconstruct the 3D temperature field based on the binocular vision system, we carry out a research on the calibration of the infrared camera. To start with, we make a calibration board which can be clearly identified by the infrared camera; then, with the help of OpenCV, we implement the calibration of two infrared cameras respectively and rectify the infrared images. According to the parameters obtained from the single infrared camera calibration, we accomplish the stereo calibration. The experimental results show that the average reprojecting error is below 0.14 pixels and when using the system to carry out a real measurement, the average error is 3.12%. The feasibility of the proposed calibration approach is verified, the experimental measurement results is close to the ground truth.