Anodized aluminum oxide membranes of tunable porosity with platinum nanoscale-coating for photonic application

Yuhai Zhang,손상준,주형규 한국물리학회 2012 Current Applied Physics Vol.12 No.6

We fabricate anodized aluminum oxide (AAO) membranes with platinum (Pt) coating of various thickness ranging from 0 nm to 12 nm. We also demonstrate the tunability of membrane porosity, to add a degree of freedom in addition to the Pt coating, for optical modulation that can be used in photonic application. The reflectance measurement and its analysis are provided based on FabryePerot etalon optics that takes into account spectral dependence of optical absorption and loss in the AAO membrane. It is revealed that the frequency-dependent optical finesse (color purity) enhances nonlinearly with the Pt thickness, by the quantitative estimation, while the effective refractive index is substantially governed by the membrane porosity. These features can allow for the AAO membrane to be used as a dye-free color displaying film with efficient tunability of both displaying color and its color purity. In particular, the strong dependence of an effective refractive index on porosity is demonstrated such that the AAO membrane can have the effective refractive index down to about 1.2, making it a possible candidate for a single layer anti-reflection coating material deposited on optical components including low-index glass. We also fabricate, by facile dipping method, an AAO membrane whose pore size changes gradually along a direction on its surface. This intra-membrane modulation of porosity allows it to find application in an optical grating or band-pass filter whose transmission wavelength varies with position on the device surface. We fabricate anodized aluminum oxide (AAO) membranes with platinum (Pt) coating of various thickness ranging from 0 nm to 12 nm. We also demonstrate the tunability of membrane porosity, to add a degree of freedom in addition to the Pt coating, for optical modulation that can be used in photonic application. The reflectance measurement and its analysis are provided based on FabryePerot etalon optics that takes into account spectral dependence of optical absorption and loss in the AAO membrane. It is revealed that the frequency-dependent optical finesse (color purity) enhances nonlinearly with the Pt thickness, by the quantitative estimation, while the effective refractive index is substantially governed by the membrane porosity. These features can allow for the AAO membrane to be used as a dye-free color displaying film with efficient tunability of both displaying color and its color purity. In particular, the strong dependence of an effective refractive index on porosity is demonstrated such that the AAO membrane can have the effective refractive index down to about 1.2, making it a possible candidate for a single layer anti-reflection coating material deposited on optical components including low-index glass. We also fabricate, by facile dipping method, an AAO membrane whose pore size changes gradually along a direction on its surface. This intra-membrane modulation of porosity allows it to find application in an optical grating or band-pass filter whose transmission wavelength varies with position on the device surface.

Modeling and Analysis of Cyber-physical Systems Based on Petri Net

Yuhai Yang,Chongquan Zhong,Xiaodong Liu,Wei Lu 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.9

Cyber-physical systems (CPS) are rapidly developing in smart factories. However, CPS for smart factories is facing great challenges in the integration of heterogeneous devices (sensors and control devices) and analysis methods like stability and expandability of systems. In this study, a comprehensive solution is provided to integrate heterogeneous devices and to analyze CPS dynamic behaviors with the aid of Petri net. Specifically, in the physical layer, a kind of controller PAG200 is used as an edge control gateway, to integrate a multitude of sensing and control devices into one system. The integrated system can assist managers to better deal with the manufacturing data captured on-site; In the cyber layer, a cyber-physical system analysis method based on Petri net is proposed. The method combines Petri net principle with cyber-physical system technology, and the purpose is to provide a graphical modeling and analysis method for information perception, device management and data processing. System extensibility is measured by coupling intensity. The necessity and priority of the elastic expansion of the system are established. The system stability and performance are analyzed from the stability probability and its related parameters. There have been enough successes to demonstrate that PAG200 can undertake the task of internet integration as an edge gateway to eliminate information gaps. Correspondingly, the extensibility of the model and the feasibility of the method are verified.

Fluorescent Magnetic Silica Nanotubes with High Photostability Prepared by the Conventional Reverse Micro-Emulsion Method

Yuhai Zhang,손상준 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.12

Magnetic fluorescent silica nanotubes were fabricated using reverse micro-emulsions coupled with conventional sol-gel methods. Anodic aluminum oxide templates were used to separate spatially the magnetic and the fluorescent moieties on individual nanotubes and so prevent quenching of the fluorescence. C18 and fluorescent layers were deposited sequentially on silica. Magnetism was then obtained by the introduction of pre-made magnetic nanoparticles inside the nanotubes. The photo- and chemical stabilities of nanotubes were demonstrated through dye release and photobleaching tests. The produced nanotubes did not show fluorescence quenching upon the addition of the nanoparticles, an advantage over conventional spherical fluorescent magnetic nanoparticles. High photostability of nanotubes, magnetism and biocompatiblily make them potentially useful in bioanalysis.

Fluorescent Magnetic Silica Nanotubes with High Photostability Prepared by the Conventional Reverse Micro-Emulsion Method

Zhang, Yuhai,Son, Sang Jun Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.12

Magnetic fluorescent silica nanotubes were fabricated using reverse micro-emulsions coupled with conventional sol-gel methods. Anodic aluminum oxide templates were used to separate spatially the magnetic and the fluorescent moieties on individual nanotubes and so prevent quenching of the fluorescence. C18 and fluorescent layers were deposited sequentially on silica. Magnetism was then obtained by the introduction of pre-made magnetic nanoparticles inside the nanotubes. The photo- and chemical stabilities of nanotubes were demonstrated through dye release and photobleaching tests. The produced nanotubes did not show fluorescence quenching upon the addition of the nanoparticles, an advantage over conventional spherical fluorescent magnetic nanoparticles. High photostability of nanotubes, magnetism and biocompatiblily make them potentially useful in bioanalysis.

Purification of papain from unclarified papaya juice using reversed phase expanded bed adsorption chromatography (RP-EBAC)

He Yuhai,Syed Mohd Saufi bin Tuan Chik,Chong Fui Chin 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6

The purification of papain using a reversed phase expanded bed adsorption chromatography (RP-EBAC)using a FastlineTM 10 EBAC column packed with AmberliteTM XAD7HP has been carried out in this study. An efficient large scale direct recovery of papain was developed and optimized from unclarified papayajuice feedstock in batch adsorption system. Enhancement of papain purity was further investigated inEBAC by stepwise elution strategy. High papain purity of 74.98% and high purification factor of 7.04 wereobtained. This study shows a great potential of using two step elution RP-EBAC system to purify papainfrom unclarified papaya juice.

A homotopy continuation method for solving a matrix equation

Jing Li,Yuhai Zhang 대한수학회 2018 대한수학회지 Vol.55 No.2

In this paper, a homotopy continuation method for obtaining the unique Hermitian positive definite solution of the nonlinear matrix equation $X-\sum_{i=1}^{m}A_{i}^*X^{-p_{i}}A_{i}=I$ with $p_{i}> 1$ is proposed, which does not depend on a good initial approximation to the solution of matrix equation.

A HOMOTOPY CONTINUATION METHOD FOR SOLVING A MATRIX EQUATION

Li, Jing,Zhang, Yuhai Korean Mathematical Society 2018 대한수학회지 Vol.55 No.2

In this paper, a homotopy continuation method for obtaining the unique Hermitian positive definite solution of the nonlinear matrix equation $X-{\sum_{i=1}^{m}}A^{\ast}_iX^{-p_i}A_i=I$ with $p_i$ > 1 is proposed, which does not depend on a good initial approximation to the solution of matrix equation.

Preparation of Silver Nanocap Arrays and Their Surface-enhanced Raman Scattering Activity

Chunxu Wang,Duo Xu,Yuhai Wang,Li Wang,Lei Chen,Xiangxin Xue,Zhengkun Qin 대한화학회 2017 Bulletin of the Korean Chemical Society Vol.38 No.10

In this article, a surface-enhanced Raman scattering (SERS) substrate of silver nanocap arrays was reported. With increasing the size of nanocaps, the localized surface plasmon resonance (LSPR) of the arrays exhibited tunable ability in the visible spectral region. The optical response of the nanocap arrays stimulated their use in SERS experiments. The assessment of SERS activity of the nanocap arrays was performed by using the 514.5 nm excitation line, and different average enhancement factor (EF) values were obtained. The good tunability of LSPR, relatively high average EF values and long-range order of these substrates suggest that the silver nanocap arrays have promising applications as functional components in spectroscopy, immunoassay, biosensors, and biochips.

Hospitalization Due to Asthma Exacerbation: A China Asthma Research Network (CARN) Retrospective Study in 29 Provinces Across Mainland China

Jiangtao Lin,Bin Xing,Huaping Tang,Lan Yang,Yadong Yuan,Yuhai Gu,Ping Chen,Xiaoju Liu,Jie Zhang,Huiguo Liu,Changzheng Wang,Wei Zhou,Dejun Sun,Yiqiang Chen,Zhuochang Chen,Mao Huang,Qichang Lin,Chengpin 대한천식알레르기학회 2020 Allergy, Asthma & Immunology Research Vol.12 No.3

Purpose: Details of patients hospitalized for asthma exacerbation in mainland China are lacking. To improve disease control and reduce economic burden, a large sample survey among this patient population is indispensable. This study aimed to investigate the clinical characteristics and outcomes of such patients. Methods: A retrospective study was conducted on patients hospitalized for asthma exacerbation in 29 hospitals of 29 regions in mainland China during the period 2013 to 2014. Demographic features, pre-admission conditions, exacerbation details, and outcomes were summarized. Risk factors for exacerbation severity were analyzed. Results: There were 3,240 asthmatic patients included in this study (57.7% females, 42.3% males). Only 28.0% used daily controller medications; 1,287 (39.7%) patients were not currently on inhaled corticosteroids. Acute upper airway infection was the most common trigger of exacerbation (42.3%). Patients with severe to life-threatening exacerbation tended to have a longer disease course, a smoking history, and had comorbidities such as hypertension, chronic obstructive pulmonary disease (COPD), and food allergy. The multivariate analysis showed that smoking history, comorbidities of hypertension, COPD, and food allergy were independent risk factors for more severe exacerbation. The number of patients hospitalized for asthma exacerbation varied with seasons, peaking in March and September. Eight patients died during the study period (mortality 0.25%). Conclusions: Despite enhanced education on asthma self-management in China during recent years, few patients were using daily controller medications before the onset of their exacerbation, indicating that more educational efforts and considerations are needed. The findings of this study may improve our understanding of hospital admission for asthma exacerbation in mainland China and provide evidence for decision-making.

Fabrication of ZIF-8/TiO2 electrospinning nanofibers for synergistic photodegradation in dyeing wastewater

Liusha Cen,Tao Tang,Fan Yu,Han Wu,Chengcai Li,Hailin Zhu,Yuhai Guo 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

Semiconductormetal–organic framework (MOF) hybrid photocatalysts become a significant material totreating dyeing wastewater recently. Zinc-based metal–organic framework (ZIF-8) stands out amongnumerous photocatalysts for its stability and simplicity to prepare. In this work, the gourd-shaped ZIF-8/TiO2 nanocomposites are prepared in situ on anatase TiO2 by precursor method, and then ZIF-8/TiO2nanocomposites is supported on PVDF electrospinning nanofibers by blending method to form ZIF-8/TiO2 nanofibers (ZIF-8/TiO2 NFs). We compare the degradation ability of Rhodamine B by ZIF-8/TiO2NFs with different mass ratios and load rates. When the mass ratio of ZIF-8 to TiO2 is 2:1 and the loadingrate is 10%, the photocatalytic degradation efficiency of ZIF-8/TiO2 NFs reached 95.4%, and the degradationremained as high as 88.7% after cycling five times. The characterization results showed that ZIF-8 andTiO2 are connected by N Ti O chemical bond, which narrows the band gap and rebars the recombinationof the electron-hole pairs. The synergistic action of ZIF-8 and TiO2 largely improves the photocatalyticcapacity of ZIF-8/TiO2 NFs.