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Polymerization of Vinyl Acetate Initiated by Hydrosilane in the Presence of Platinum Complex
Ming Yuan,Wenxian Zhu,Jiaxing Lv,Panpan Zhang,Huadong Tang 한국고분자학회 2021 폴리머 Vol.45 No.3
In this work, a series of hydrosilanes including phenylsilane, diphenylsilane, triethylsilane (TES), and tris(trimethylsilyl)silane combined with catalytical amount of platinum complex such as dichloro(1,5-cyclooctadiene) platinum (COD) and dichloro(dicyclopentadienyl)platinum have been used to initiate the polymerization of vinyl acetate (VAc) at 70-95 ℃. An ultrahigh molecular weight PVAc with number-average molecular weight (Mn) up to 1.17×10<SUP>6</SUP> Da and polydispersity index (PDI) of 2.59 has been synthesized using TES as an initiator in the presence of 9.7 ppm of COD. A kinetic study indicates that the polymerization at VAc/TES/COD molar ratio = 3.0×10<SUP>5</SUP> : 60 : 1 smoothly reached 81.0% conversion in 28.0 h at 85 ℃, producing PVAc with Mn increasing linearly from 1.41×105 to 6.01×10<SUP>5</SUP> Da with the increase of monomer conversion. A mechanistic investigation revealed that COD was firstly reduced by reductive TES, producing Pt nanoparticles and corresponding silane radicals to initiate the polymerization of VAc.
Privet golden leaves adapt unexpectedly well to light changes
Ming Yuan,Bo Huang,Li-Hua Dong,Qiao-Hong Han,Yong Yang,Chun-Bang Ding,Chao Hu,Yang-Er Chen,Zhong-Wei Zhang,Shu Yuan 한국원예학회 2020 Horticulture, Environment, and Biotechnology Vol.61 No.4
Golden-leaf privet ( Ligustrum × vicaryi ) is widely used as a horticultural shrub because of its upper golden leaves, butits lower leaves are green. However, the putative mechanisms of its upper golden leaves and the leaf color changes inresponse to light shifts have not been well studied so far. Here, chlorophylls (Chl), carotenoids, and Chl precursors from bothgolden and green leaves grown in full sunlight (approximately 1200 μmol photons m −2 s −1 at noon) or low-light conditions(180 μmol m −2 s −1 ) were determined spectrophotometrically. In addition, their gas exchange parameters and Chl fl uorescencewere measured in situ. Metabolic fl ux analysis of chlorophyll intermediates indicated that the conversion of prochlorophyllideto chlorophyllide was signifi cantly blocked in golden leaves when compared with green leaves. Green leaves showed higherphotosynthetic capacity in low light than golden leaves, but golden leaves presented unexpectedly stronger photosyntheticcapacity and lower reactive oxygen species accumulation under the high-light condition. Furthermore, golden leaves showeda higher level of nonphotochemical quenching (NPQ) after the light-to-dark shift and presented a stronger adaptive abilityto a broad range of light environments. Higher NPQ values and less oxidative damage in golden leaves may be correlatedwith their higher carotenoid levels. The results imply that lower chlorophyll levels and higher carotenoid levels in canopyleaves may help privet plants acclimate better to illumination changes. This study demonstrates the key role of irradiance ingenerating the two types of Ligustrum × vicaryi leaves and sheds a light on cultivation of other ornamental foliage plants.
Ming Yuan,Xuejing Jia,ChunBang Ding,Haiqiong Zeng,Lei Du,Shu Yuan,Zhongwei Zhang,Qi Wu,Chao Hu,Jing Liu 한국식품과학회 2015 Food Science and Biotechnology Vol.24 No.5
Effects of light on phenolic compounds and antioxidant activities during germination of soybean seeds were studied. Soybean seeds were germinated in the presence and absence of light. Chlorophylls and morphological characteristics of sprouts were evaluated daily. Antioxidant activities were determined using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and ferric reducing activity power methods. Morphological characteristics of light-grown sprouts were superior to dark-grown sprouts and the metabolism of phenolic compounds was regulated by light. Light treatment improved accumulation of phenolic compounds in soybean sprouts and increased antioxidant activities. The optimum harvest time of light-grown sprouts was on the seventh day when sprouts achieved the best nutraceutical value. Green sprouts can serve as a good vegetable source for the human diet.
A Density-based Binary SVM Algorithm in the Cloud Security
Mingyuan Yu,Shuhang Huang,Qing Yu,Yan Wang,Jiaquan Gao 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.7
In recent years, cloud computing is becoming popular in the field of information, however, the development of cloud computing have to face the problem of cloud security. Intrusion Deletion System (IDS) is one of the possible solutions to the problem of cloud security, but the correct rate of general application of the IDS is not very satisfactory, for this purpose we propose a density-based binary Support Vector Machine (SVM) method (D-BSVM). Its main idea is based on the density of each class in the data set, and gets a binary sequence of training, according to this sequence obtained binary SVM training model to predict the behavior of the system. Further, the method for calculating the density is the paralleled, thereby improving efficiency of overall system. Finally, we present experimental results, and by contrast our approach can improve the accuracy and detection rate of IDS.
Mingyuan Li,Hongru Yu,Qingqiao Geng,Yuanli Gu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1
Based on operation kilometers, amounts and station numbers of urban rail transit (URT) lines in a city, this study utilizes simultaneous panel data equations (SPDE) to comprehensively analyze the bidirectional dynamics of urban rail transit (URT) on urban economies. Drawing on data from 2010 to 2019 across 40 Chinese cities, we rigorously examine the SPDE model's robustness through elastic analysis and placebo tests. Economic variables within the SPDE framework are aggregated based on geographic population scales, yielding new endogenous variables that facilitate a deeper exploration of URT's impact on economic agglomeration. Our findings highlight URT's positive spillover effects, promoting both geographic and demographic economic agglomeration. Nevertheless, it is imperative to note that URT's capacity to ameliorate economic conditions remains constrained in cities with sluggish or stagnant development.
Mingyuan Zhu,Ling Tang,Guangqing Luo,Lihua Kang,Bin Dai 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.2
To effectively reduce the sulfur content in model fuel, [Bmim]PW/HMS catalyst was synthesized through impregnating the hexagonal mesoporous silica (HMS) support by phosphotungstic acid (HPW) and ionic liquid [Bmim]HSO4. Physical structure characterizations of the catalysts showed that HMS retained mesoporous structure, and [Bmim]PW was well dispersed on the support of HMS. The catalytic activity of the [Bmim]PW/HMS was evaluated in the oxidative desulfurization process, and the optimal reaction conditions including loading of the catalysts, reaction temperature,catalyst amount, O/S (H2O2/sulfur) molar ratio and agitation speed were investigated. Under the optimal reaction conditions, the conversion of benzothiophene (BT), dibenzothiophene (DBT) and 4, 6-dimethyldibenzothiophene (4,6-DMDBT) could reach 79%, 98%, 88%, respectively.
Self-Assembly of Pentacene on Sub-nm Scale Surface Roughness- Controlled Gate Dielectrics
Mingyuan Pei,고중세,신환호,조민상,백지민,김규동,육지호,양회창 한국고분자학회 2018 Macromolecular Research Vol.26 No.10
Surface roughness (R q) of dielectric materials plays an important role in the ordering and charge-carrier transport of organic semiconductors, and is directly involved in the development of nuclei and crystal grains on a surface. To investigate the effect of R q-controlled dielectrics with similar surface energy (γ) on the development of nuclei and crystal grain, a series of triethoxysilane-terminated polystyrene (PSTES) polymers with different molecular weights (MW) values is synthesized using reversible addition-fragmentation chain transfer polymerization. The different MW PS-TES films are spun-cast on a hydroxyl (-OH)-rich SiO2 dielectric surface, and chemically coupled with -OH moieties at 110 °C. Some films are also rinsed with an excess of toluene to remove unreacted polymer residue, increasing the average R q values of the treated SiO2 surfaces. The resulting polymer-treated dielectrics show similar surface energy values of 41.6-42.5 mJ m-2 but different R q values ranging from 0.29 to 1.07 nm. On the nanoscale roughness-controlled dielectric surfaces, 40-nm-thick pentacene films show discernible types of crystal grains with different phases, shapes, sizes, and ordering, all of which significantly affect charge-carrier transport along π-conjugated semiconductors in organic field-effect transistors (OFETs). Pentacene OFETs show large variations in fieldeffect mobility (μFET) from 0.89 to 0.19 cm2 V-1 s-1. Specifically, at R q=0.40 nm the μFET value suddenly decreases to 0.30 cm2 V-1 s-1. On polymer treated SiO2 dielectrics with an R q value greater than 0.40 nm, polymorphic, less-ordered, and smaller grains of pentacene containing large number of charge trap sites developed, resulting in significantly degraded charge-carrier transport along the intra- and inter-grains in OFETs, in comparison to the well-ordered grains on smooth polymer-treated surfaces (R q< 0.40 nm).