Morphology-dependent Optical Properties of One-dimensional Nanostructure-arrayed Silicon

Shao-long Wu,Guo-an Cheng,Rui-ting Zheng,Xiao-ling Wu 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.6

The optical properties of one-dimensional nanostructure-arrayed silicon (1DNSASi), which wasfabricated by the metal assisted electroless chemical etching method under different conditions,were characterized in the wavelength range of 220 - 1000 nm. Whether the optical absorption ofthe 1DNSASi was enhanced relative to that of the polished Si was determined from the detailedmorphology of the 1D nanostructures. For the yellow 1DNSASi prepared at a high etchant concentrationand high temperatures, its optical absorption was relatively nice in the ultraviolet lightregion, while a gradual attenuation was shown in the visible and the near-infrared regions, and theoptical absorption was lower than that of the polished Si at wavelengths above 800 nm. When theeffects of zeroth-order reflectance and zero transmission were combined, the optical absorption ofthe black 1DNSASi prepared at a low etchant concentration and room temperature was very high(> 99%) in the wavelength range of 220 - 1030 nm and displayed a slight decrease at wavelengthsabove 1030 nm. Our results demonstrate that the optical absorption of the black 1DNSASi couldbe further improved by increasing the etching depth and exhibited its measurable maximum valuewhen the etching depth was large enough. These results indicate that the 1DNSASi may be apromising candidate for high-efficiency photovoltaic devices, high-sensitivity sensors and detectors.

Association between Cigarette Smoking and RASSF1A Gene Promoter Hypermethylation in Lung Cancer Patients: a Meta-analysis

Wu, Xiao-Ming,Chen, Yu,Shao, Yang,Zhou, Xiao-Long,Tang, Wen-Ru Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.19

Objectives: Epidemiological studies have shown that molecular mechanisms underlying the development of lung cancers differ between smokers and unsmokers. Aberrant promoter methylation in some tumor suppressor genes is frequent in lung tumors from smokers but rare in those from non-smokers. Recently, many studies have investigated the association between cigarette smoking and RASSF1A gene promoter hypermethylation in lung cancer patients, but a unanimous conclusion could not be reached. We therefore performed this meta-analysis to derive a more precise estimation of any association. Study Design: An electronic search of PubMed and Chinese Biomedicine databases was conducted to select studies. A total of 19 case-control studies were chosen, and odds ratios (ORs) with confidence intervals (CIs) were used to assess the strength of associations. Results: The case-control studies covered 2, 287 lung cancer patients: 63.4%(1449) of the patients were smokers, 36.6% (838) were unsmokers. The overall results suggested that smokers with lung cancer had a 1.297-fold (95% CI: 1.066~1.580, p=0.010, p=0.087) higher risk for RASSF1A gene hypermethylation than the non-smokers. In the stratified analysis, an increased risk of RASSF1A gene hypermethylation in smokers than in non-smokers was found in Asian (OR=1.481, 95%CI: 1.179~1.861, p=0.001, p=0.186). Conclusions: This meta-analysis supports the idea that RASSF1A gene hypermethylation is associated with cigarette smoking-induced lung cancer.

Anomalous Propagation Characteristics of an Airy Beam in Nonlocal Nonlinear Medium

Yun-Long Wu,Qin Ye,Li Shao 한국광학회 2021 Current Optics and Photonics Vol.5 No.2

The anomalous propagation characteristics of a single Airy beam in nonlocal nonlinear medium are investigated by utilizing the split-step Fourier-transform method. We show that besides the normal straight propagation trajectory, the breathing solitons formed by the interaction between Airy beam and nonlocal nonlinear medium can propagate along the sinusoidal trajectory, and the anomalous trajectory can be modulated arbitrarily by altering the initial amplitude and the nonlocal nonlinear coefficient. In addition, the initial amplitude and the nonlocal nonlinear coefficient can have inverse impacts on the formation and transformation of the equilibrium state of spatial solitons, when the two parameters are larger than certain values. Therefore, the reversible transformation of the evolution dynamics of two soliton states can be realized by adjusting those two parameters properly. Finally, it is shown that the propagation properties of the solitons formed by the interaction between Airy beam and nonlocal nonlinear medium can be controlled arbitrarily, by adjusting the distribution factor and nonlocal coefficient.

A Novel Form Analysis Method Considering Pretension Process for Suspen-dome Structures

Zhen Zhou,Yu-long Feng,Shao-ping Meng,Jing Wu 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.5

Suspen-dome is a kind of new prestressed space grid structure which is formed by combing a single-layer reticulated shell andtensegrity system. For the existence of lower flexible cable-strut system, form analysis is crucial for the mechanical performance ofsuspen-domes. This paper develops a novel form analysis method considering the influence of pretension process for suspen-domestructures. Some definitions of form analysis for suspen-dome structures are first expounded. Then an iterative method is presentedfor form analysis, and a sequential analysis method is proposed for pretension process simulation. By combining these two methods,a form analysis method considering pretension process is constructed for suspen-dome structures. Two examples are employed toverify the proposed method. Numerical example results show that both the error of nodal coordinates and cable forces can stablyconverge to set tolerances. According to a scheduled pretension scheme, form analysis results can accurately achieve the expectedinitial state. Engineering example results show that without considering the influence of pretension process, the form analysis wouldbe error and the final state after all cables tensioned deviates greatly from the expected initial state. However, this can be achievedaccurately through the proposed method in this paper.

Fabrication and Electron Field Emission of Silicon Nanowires Synthesized by Chemical Etching

Fei Zhao,Dan-dan Zhao,Shao-long Wu,Guo-an Cheng,Rui-ting Zheng 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.6

Vertically aligned silicon nanowire arrays, which were synthesized by using a Ag catalyst deposited with magnetron sputtering and an electrochemical etching process were investigated. The thickness of the Ag catalyst affects the microstructure of aligned silicon nanowire array. Vertically aligned silicon nanowire arrays with more uniform morphology structures were synthesized with a catalyst thickness of 40 nm on a single crystal silicon wafer at room temperature. The electron field emission data showed a lower turn-on field for silicon nanowire arrays fabricated with the electrochemical etching process. The field enhancement factor of the silicon nanowire arrays is as high as 1637. These data indicate that electrochemical etching technology is a cheap and good method for fabricating vertically aligned silicon nanowire arrays for applications in field emission devices. Vertically aligned silicon nanowire arrays, which were synthesized by using a Ag catalyst deposited with magnetron sputtering and an electrochemical etching process were investigated. The thickness of the Ag catalyst affects the microstructure of aligned silicon nanowire array. Vertically aligned silicon nanowire arrays with more uniform morphology structures were synthesized with a catalyst thickness of 40 nm on a single crystal silicon wafer at room temperature. The electron field emission data showed a lower turn-on field for silicon nanowire arrays fabricated with the electrochemical etching process. The field enhancement factor of the silicon nanowire arrays is as high as 1637. These data indicate that electrochemical etching technology is a cheap and good method for fabricating vertically aligned silicon nanowire arrays for applications in field emission devices.

Analysis of Pressure Distribution of the Bolted Joints Based on the Finite Element Method

Sheng-ao Wang,Min Zhu,Fei Wu,Tian-xi Liang,Zhao-qun Shao,Yi-long Liu 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.2

Bolted joints widely exist in the field of the national defense industry. However, its nonlinear stiffness degradation will occur under tangential load which may lead to the reliability reduction. According to Coulomb friction theory, the pressure distribution is the key in the tangential degradation of bolted joints. Therefore, this paper aims to analyze the pressure distribution of bolted joints. Firstly, we established a threaded bolt model and two simplified models. Secondly, the accuracy of the three models describing the contact area is verified, and the influence of preload and material properties on the contact radius is analyzed. Thirdly, we compared the pressure distribution of the three models, and results show that the smooth bolt model is more suitable for pressure analysis. Finally, the accuracy of several different functions to characterize the pressure distribution of bolted joints is analyzed, and results indicated that the Fernlund function is optimal. This paper provides a feasible simplified bolt model for finite element analysis, and the optimal pressure distribution function can be applied in the tangential stiffness degradation modeling.