Pyrolysis kinetics and microstructure of thermal conversion products on toluene soluble component from two kinds of modified pitch

Yaming Zhu,Xuefei Zhao,Lijuan Gao,Junxia Cheng 한국탄소학회 2018 Carbon Letters Vol.28 No.-

Modified pitch A (MPA) and modified pitch B (MPB) were prepared by oxidative polymerization and thermal polycondensation reaction with refined pitch as the raw material, respectively. The toluene soluble components (TS-1 and TS-2) were obtained by solvent extraction from MPA and MPB, separately. The Flynn-Wall-Ozawa method and Kissinger-Akahira- Sunose method were used to calculate the pyrolysis activation energy of TS. The Satava- Sestak method was used to investigate the pyrolysis kinetic parameters of TS. Moreover, the optical microstructure of the thermal conversion products (TS-1-P and TS-2-P) by calcination shows that TS-1-P has more contents of mosaic structure and lower contents of fine fiber structure than TS-2-P. The research result obtained by a combination of X-ray diffraction and the curve-fitting method revealed that the ratios of ordered carbon crystallite (Ig) in TS-1-P and TS-2-P were 0.3793 and 0.4417, respectively. The distributions of carbon crystallite on TS-1-P and TS-2-P were calculated by Raman spectrum and curve-fitting analysis. They show that the thermal conversion product of TS-2 has a better graphite crystallite structure than TS-1.

Changes in structure of coal liquefied pitch during liquid‑phase carbonization process

Yaming Zhu,Xuefei Zhao,Ji Yuan,Chunlei Zhao,Chaoshuai Hu 한국탄소학회 2019 Carbon Letters Vol.29 No.1

residue as the raw material. As one of the preconceived raw material to produce high-quality coal-based carbon material, the changes of structure of CLP during liquid-phase carbonization process have been detailed investigated in this study. Actually, FTIR and curve-fitted method were used to quantitative analyze the aromaticity index (Iar), the ratio of CH3/ CH2, and basic functional groups (C=C, C=O, and C–O) of CLP and its liquid-phase carbonization products. Polarizing microscope, XRD and curve-fitted methods were used to characterize the microstructures of CLP and derived products. The results show that, branched chain and C=O group are the active reaction point in liquid-phase carbonization process. What’s more, 450 °C is a critical temperature point on the severe thermal polycondensation of CLP. The XRD and curve-fitted analysis of CLP and its liquid-phase carbonization products shows that, the stacking height (Lc), parallel layers (N), and the numbers of aromatic ring in each layer (n) are gradually larger with the improve of liquid-phase carbonization temperature.

Roles of CYP1A1 and CYP2E1 Gene Polymorphisms in Oral Submucous Fibrosis

Yaming, Punyo,Urs, Aadithya Basavaraj,Saxena, Alpana,Zuberi, Mariyam Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.7

Background: Oral submucous fibrosis (OSF) is a precancerous condition with a 4 to13% malignant transformation rate. Related to the habit of areca nut chewing it is mainly prevalent in South-east Asian countries where the habit of betel quid chewing is frequently practised. On chewing, alkaloids and polyphenols are released which undergo nitrosation and give rise to N-nitrosamines which are cytotoxic agents. CYP450 is a microsomal enzyme group which metabolizes various endogenous and exogenous chemicals including those released by areca nut chewing. CYP1A1 plays a central role in metabolic activation of these xenobiotics, whereas CYP2E1 metabolizes nitrosamines and tannins. Polymorphisms in genes that code for these enzymes may alter their expression or function and may therefore affect an individuals susceptibility regarding OSF and oral cancer. The present study was therefore undertaken to investigate the association of polymorphisms in CYP1A1 m2 and CYP2E1 (RsaI/PstI) sites with risk of OSF among areca nut chewers in the Northern India population. A total of 95 histopathologically confirmed cases of OSF with history of areca nut chewing not less than 1 year and 80, age and sex matched controls without any clinical signs and symptoms of OSF with areca nut chewing habit not less than 1 year were enrolled. DNA was extracted from peripheral blood samples and polymorphisms were analyzed by PCR-RFLP method. Gene polymorphism of CYP1A1 at NcoI site was observed to be significantly higher (p = 0.016) in cases of OSF when compared to controls. Association of CYP1A1 gene polymorphism at NcoI site and the risk of OSF (Odd's Ratio = 2.275) was also observed to be significant. However, no such association was observed for the CYP2E1 gene polymorphism (Odd's Ratio = 0.815). Our results suggest that the CYP1A1 gene polymorphism at the NcoI site confers an increased risk for OSF.

Geochronology, geochemistry, Hf isotope, and electron probe analysis of the diorite in the Jianhei Mountain, East Kunlun Orogenic Belt, China, and their geological significance

Yaming Sun,Bile Li,Peng Li,Zhihua Li,Yufan Shi,Runtao Yu 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.6

The spatial distribution of flow units and reductant within a sandstone uranium reservoir is very beneficial for exploring the uranium mineralization mechanism; however, such studies have been almost neglected. As such, this paper aims to provide the sedimentological interpretation and heterogeneity models of the sandstone of the Middle Jurassic Zhiluo Formation at Shiwan outcrop area, in the eastern Ordos Basin. The outcrops are sandstone-dominated subaqueous distributary channel successions, in which five distinct architectural elements are identified and interpreted: channel units (CU), downstream accretion elements (DA), lateral accretion elements (LA), sandy bedforms (SB) and no-channelized fine-grained sediments (NFS). Within the sandstone succession, six flow units are present in the middle and lower parts of CU, or the lower parts of DA and SB elements, with their geometry to be controlled by the fourth- or third-order bounding surfaces. Moreover, the carbonaceous debris-rich zones (CDZ) are places with the highest abundance of reductant and preserve exclusively upon the basal erosional surfaces of CU and DA elements. Based on those results, a prediction model is established and shows that the formation of interlayer oxidation zone is strongly selective and confined within the CU and DA elements. The favorable site of uranium mineralization is preferentially distributed in the transition zone between the front of flow unit and the CDZ.

A comparative study of hybrid models combining various kinetic and regression models for p-xylene oxidation

Yaming Dong,Xuefeng Yan 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.10

The hybrid modeling approach, which combines kinetic and regression module parts to an overall processmodel, is an attractive process modeling approach. However, the selection of various kinetic and regression modelsaffects the hybrid model performance. As an illustrating example, we investigated the p-xylene (PX) oxidation processand summarized the published results of the PX oxidation kinetic model. The kinetic parameters of three kinetic models(i.e., three frequently used kinetic models of PX oxidation) were estimated and the fitting results were evaluated. Sixhybrid models were then developed based on these three kinetic models and two regression models (artificial neuralnetwork and support vector regression). Afterwards, a comparative study of the six hybrid models was carried out basedon various kinetic and regression models. The performances of these kinetic and regression models on the hybrid modelswere also evaluated. Finally, the best suitable hybrid model was obtained for the PX oxidation process.

The donor bound exciton states in wurtzite GaN quantum dot

Yaming Liu,Congxin Xia,Shuyi Wei 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Based on the effective mass approximation, the donor bound exciton states in a wurtzite (WZ) GaN/AlGaN quantum dot (QD) are investigated by means of a variational method, including the strong built-in electric field effect due to the spontaneous and piezoelectric polarizations. Numerical results show that the donor bound exciton binding energy is highly dependent on the impurity position and QD size. In particular, we find that the donor bound exciton binding energy is insensitive to dot height when the impurity is located at the right boundary of the WZ GaN/AlGaN QD with large dot height. Based on the effective mass approximation, the donor bound exciton states in a wurtzite (WZ) GaN/AlGaN quantum dot (QD) are investigated by means of a variational method, including the strong built-in electric field effect due to the spontaneous and piezoelectric polarizations. Numerical results show that the donor bound exciton binding energy is highly dependent on the impurity position and QD size. In particular, we find that the donor bound exciton binding energy is insensitive to dot height when the impurity is located at the right boundary of the WZ GaN/AlGaN QD with large dot height.

High Emissivity Ceramic Coatings Fabricated on Light Metals by PEO: Microstructure and Heat Dissipation Property

Yaming Wang,Shuqi Wang,Yongchun Zou,Guoliang Chen 한국표면공학회 2023 한국표면공학회 학술발표회 초록집 Vol.2023 No.11-1

New aspect of technology adoption: a case study of students’ self-made English-learning video

Yaming Tai,Yu-Liang Ting 서울대학교 교육연구소 2016 Asia Pacific Education Review Vol.17 No.4

Understanding how students perceive and adopt technology in their daily life is particularly relevant to today’s Information and Communication Technology (ICT) environment, in which versatile ICT tools are becoming more and more pervasive, almost ubiquitous in our day-to-day activities. In the context of English as a foreign language, this study investigates how Chinese students produce an English video with over-the-counter technology tools for accomplishing a language-learning task. In particular, this study probes into how youngsters today respond to a given learning task, how and why they adopt technology tools available and of use to them for the task. Data collection is through observation, students’ reports, and interviews. The focus on specific case study settings offers a closer look at how the use of technology tools is socially and technologically shaped in each individual case. Students reported that they welcomed and valued such learning experience and had in general positive attitude toward the tools and their use in learning. The results reveal students’ willingness and capability in adopting technology tools, whether familiar or unfamiliar to them, and appropriating these tools to fulfill their individual leaning needs. Implications have been drawn to provide a new aspect of technology adoption in school learning.

The improved corrosion resistance and fatigue properties of 2024 Al alloy treated by SMAT and MAO process

Yaming Wang,Lei Wen,Yongchun Zou,Dechang Jia,Yu Zhou 한국표면공학회 2017 한국표면공학회 학술발표회 초록집 Vol.2017 No.11

ALMOST-PRIMES REPRESENTED BY p + a^m

Lu, Yaming The Kangwon-Kyungki Mathematical Society 2016 한국수학논문집 Vol.24 No.1

Let $a{\geqslant}2$ be a xed integer in this paper. By using the method of Goldston, Pintz and Yildirm, we will prove that there are innitely many almost-primes which can be represented as $p+a^m$ in at least two dierent ways.