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Li, Xiuhua,Wu, Xue,Kim, Ji Man,Kim, Sung Soo,Jin, Mingshi,Li, Donghao Springer-Verlag 2009 Journal of the American Society for Mass Spectrome Vol.20 No.11
<P>Mesoporous silica, SBA-15 was successfully functionalized with quinoline moiety, and was applied as a matrix in the MALDI-TOF-MS analysis of small molecules. The modified SBA-15 material [SBA-15-8-(3-(triethoxysilyl)propoxy) quinoline, SBA-15-8QSi] was obtained by using calcined SBA-15 and 8-hydroxy quinoline. The structure of the functionalized mesoporous material was systemically characterized by TEM, the N<SUB>2</SUB> adsorption-desorption isotherm technique and FT-IR spectra. Compared with DHB and SBA-15, SBA-15-8QSi demonstrated several advantages in the analysis of small molecules with MALDI-TOF-MS, such as less background interference ions, high homogeneity, and better reproducibility. Based on these results, the various analytical parameters were optimized. The ideal operating conditions were (1) methanol used as the dissolving solvent; (2) sample first dropping method; (3) a ratio between the analyte and the matrix of 3.5:10. Under these optimization conditions, a low detection limit (8 pmol for L-Arginine-HCl) and high reproducibility (≤29%) were obtained. This technique was successfully applied to the analysis of various types of small molecules, such as saccharides, amino acids, metabolites, and natural honey.</P>
Smart Anti-jamming Mobile Communication for Cloud and Edge-Aided UAV Network
( Zhiwei Li ),( Yu Lu ),( Zengguang Wang ),( Wenxin Qiao ),( Donghao Zhao ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.12
The Unmanned Aerial Vehicles (UAV) networks consisting of low-cost UAVs are very vulnerable to smart jammers that can choose their jamming policies based on the ongoing communication policies accordingly. In this article, we propose a novel cloud and edge-aided mobile communication scheme for low-cost UAV network against smart jamming. The challenge of this problem is to design a communication scheme that not only meets the requirements of defending against smart jamming attack, but also can be deployed on low-cost UAV platforms. In addition, related studies neglect the problem of decision-making algorithm failure caused by intermittent ground-to-air communication. In this scheme, we use the policy network deployed on the cloud and edge servers to generate an emergency policy tables, and regularly update the generated policy table to the UAVs to solve the decision-making problem when communications are interrupted. In the operation of this communication scheme, UAVs need to offload massive computing tasks to the cloud or the edge servers. In order to prevent these computing tasks from being offloaded to a single computing resource, we deployed a lightweight game algorithm to ensure that the three types of computing resources, namely local, edge and cloud, can maximize their effectiveness. The simulation results show that our communication scheme has only a small decrease in the SINR of UAVs network in the case of momentary communication interruption, and the SINR performance of our algorithm is higher than that of the original Q-learning algorithm.
Minseon Kim,Donghao Li,Won-Joon Shim,Jae-Ryoung Oh,Jongman Park* 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.3
Environmentally important phthalic esters have been analyzed by GC-MS in terms of individual phthalic esters or total phthalic esters directly or after derivatization. Derivatization improves the chromatographic characteristics of the highly polar phthalic esters. This study focused on the GC-MS determination of the total phthalic esters and the individual phthalic esters simultaneously. The phthalic esters were hydrolyzed to phthalate and corresponding alcohols in 1 M NaOH solution at 90 oC for 30 min followed by extraction with ethyl acetate after acidifcation. The phthalic acid and alcohols were simultaneously silyl derivatized using bis(trimethylsilyl)trifluoroacetamide (BSTFA) to their corresponding silyl ester and ethers in the mixture of 60% acetone and 40% ethyl acetate at room temperature within 30 min. Because of the high reactivity of BSTFA with the phthalic acid and alcohols effective silyl derivatization was possible simultaneously. GC-MS analysis of the silyl derivatives of phthalic acid and alcohols was performed. The total phthalic ester content was estimated from the analytical result of phthalic silyl ester, while the individual phthalic ester was quantified from the analytical results of alcoholic silyl ethers. This technique was applied to spiked tab water and real seawater samples from the Lake Shihwa in Korea. The results were checked against the results from the direct GC-MS analysis of the phthalic esters and reasonable recoveries with high sensitivity were achieved. The recoveries were higher than 75% with low relative standard deviation (below 10%).
In situ measurement-based partitioning behavior of perfluoroalkyl acids in the atmosphere
Seung-Kyu Kim,Donghao Li,Kurunthachalam Kannan 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.3
Environmental fate of ionizable organic pollutants such as perfluoroalkyl acids (PFAAs) are of increasing interest but has not been well understood because of uncertain values for parameters related with atmospheric interphase partitioning behavior. In the present study, not only the values for air-water partition coefficient (KAW) and dissociation constant (pKa) of PFAAs were induced by adjusting to in situ measurements of air-water distribution coefficient between vapor phase and rainwater but also gas-particle partition coefficients were also estimated using three-phase partitioning model of ionizable organic pollutants, in situ measurements of PFAAs in aerosol and air vapor phase, and obtained parameter values. The pKa values of PFAAs we obtained were close to the minimum values suggested in literature except for perfluorooctane sulfonic acids, and COSMOtherm-modeled KAW values were assessed to more appropriate among suggested values. When applying parameter values we obtained, it was predicted that air particle-associated fate and transport of PFAAs could be negligible and PFAAs could distribute ubiquitously along the transection from urban to rural region by pH-dependent phase transfer in air. Our study is expected to have some implications in prediction of the environmental redistribution of other ionizable organic compounds.
Guizhong Tian,Zhengyu Ma,Donghao Zhao,Honggen Zhou,Xuwen Jing,Zhancheng Xie,Guochao Li 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
The residual stresses (RS) generated during the thermal processing processes such as casting and heat treatment is one of the fundamental causes of irreversible deformation of diesel engine bodies (DEBs). However, previous studies only focused on the RS generated from casting or the effect of annealing heat treatment on the RS in castings unilaterally, and the analytical results were far from the actual conditions. Therefore, this paper proposes a comprehensive research method to consider the whole dynamic evolution of the casting from the RS generated by casting to the stress relief by heat treatment. Numerical simulation of DEBs casting process is carried out by PROCAST, and the results of casting RS obtained from the simulation are imported into ABAQUS, and then numerical simulation of annealing heat treatment is carried out for the DEB casting model with casting RS, so as to realize the analysis of dynamic evolution of RS from casting to heat treatment.
Won Joon Shim,홍상희,오재룡,임운혁,Donghao Li,Narayanan Kannan 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.4
Measurement of toxicologically relevant polychlorinated biphenyl (PCB) congeners such as non-ortho (IUPAC#) 77, 81, 126, 169 and mono-ortho 105, 114, 118, 123, 156, 157, 189 and di-ortho 170, 180 and polybrominated diphenyl ethers (PBDEs) such as 47, 66, 85, 99, 100, 138, 153, 154 in environmental samples become almost mandatory in several countries now. However, most of the available methods involve expensive instrumentations such as HRGC-HRMS or ECNI-LRMS, apart from expensive extraction and clean-up (with large volume of solvents) steps. A method has been devised combining the analytical separation power of PYE [2-(1-pyrenyl)ethyldimethysilylated silica] column HPLC and high-resolution gas chromatographic techniques including micro-electron capture detection (ECD) and two dimensional gas chromatograpy-ECD techniques to determine these eco-toxic substances at parts-per-trillion (ppt) levels. This combination resolves co-elution of congeners that occur in disproportionate ratios (e.g. CB-110 and -77) and allows accurate congener-specific determination of target compounds. This method is cost effective as it requires only hexane, that in small quantities (10 mL) and GC-ECD. The elution and analysis time are optimized to less man hours. This method is effectively utilized in the analysis of co-planar PCBs and PBDEs from archived solvent extracts of samples previously analyzed for pesticides and PCBs. Structure based separation of contaminant classes improves GC-ECD determination at ppt levels.
노경호,Yinzhe Jin,Dong Wha Park,Xifeng Li,Donghao Li 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4
To determine the volatile compounds in Rhodiola sachalinensis, hydro-distillation (HD) and headspace liquid-phase micro-extraction (HS-LPME) were used to extract 75 and 68 volatiles, respectively. Geraniol (24.73%),n-octanol (15.56%), and linalool (14.51%) were the most abundant essential oils detected in the HD samples, while geraniol (24.17%) and n-octanol (15.81%) were also detected at high levels in the HS-LPME samples. The main chemical classes of the essential oils were monoterpene alcohols in both the HD and HS-LPME samples at 59.02% and 37.64%,respectively. The O-heterocyclic (8.52%) and aromatic (5.92%) compounds were more abundant in the HS-LPME samples than in the HD samples.
Miao He,Qingjuan Xu,Cui Yang,Xiangfan Piao,Narayanan Kannan,Donghao Li 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.10
A sensitive concentration method utilising modified gas-purge microsyringe extraction (GP-MSE) was developed. Concentration (reduction in volume) to a microlitre volume was achieved. PAHs were utilised as semivolatile analytes to optimise the various parameters that affect the concentration efficiency. The injection rate and temperature were the key factors that affected the concentration efficiency. An efficient concentration (75.0−96.1%) of PAHs was obtained under the optimised conditions. The method exhibited good reproducibility (RSD values that ranged from 1.5 to 9.0%). The GP-MSE concentration method enhances the volume reduction (concentration factor), leading to a low method detection limit (0.5−15 ng L–1). Furthermore, this method offers the advantage of small-volume sampling, enabling even the detection of diurnal hourly changes in the concentration of PAHs in ambient air. Utilising this method in combination with GC−MS, the diurnal hourly flux of PAHs from the gas phase of ambient air was measured. Indeed, the proposed technique is a simple, fast, low-cost and environmentally friendly.