Kinetics studies of dimethyl carbonate synthesis from urea and methanol over ZnO catalyst

Wei Wei,Junliang Zhang,Feng Wang,Fukui Xiao,Yuhan Sun 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.6

A kinetic experiment of dimethyl carbonate (DMC) synthesis by urea methanol over ZnO catalyst was carried out in an isothermal fixed-bed reactor. A kinetic model based on the mole fraction was proposed and the kinetic parameters were estimated from the experimental results. The model predictions were compared with the experimental data and fair agreements were found. The effects of the reaction temperature (443-473 K), space time (0-4.7 h mol−1kgcat) and urea mass percent (5-9%) in feed on DMC mole fraction were investigated. It was found that the reactions are mainly influenced by the reaction temperature and space time rather than urea mass percent in feed. The experimental and simulated results indicated that the reaction from MC to DMC was the rate-controlling step in the DMC synthesis process from urea and methanol. It is important to remove the DMC and byproduct ammonia to achieve a high selectivity of DMC. This implies that reactive distillation might be used in the DMC synthesis on an industrial scale to achieve a higher selectivity of DMC.

The genome of the mesopolyploid crop species Brassica rapa

Wang, Xiaowu,Wang, Hanzhong,Wang, Jun,Sun, Rifei,Wu, Jian,Liu, Shengyi,Bai, Yinqi,Mun, Jeong-Hwan,Bancroft, Ian,Cheng, Feng,Huang, Sanwen,Li, Xixiang,Hua, Wei,Wang, Junyi,Wang, Xiyin,Freeling, Michael Nature Publishing Group, a division of Macmillan P 2011 Nature genetics Vol.43 No.10

We report the annotation and analysis of the draft genome sequence of Brassica rapa accession Chiifu-401-42, a Chinese cabbage. We modeled 41,174 protein coding genes in the B. rapa genome, which has undergone genome triplication. We used Arabidopsis thaliana as an outgroup for investigating the consequences of genome triplication, such as structural and functional evolution. The extent of gene loss (fractionation) among triplicated genome segments varies, with one of the three copies consistently retaining a disproportionately large fraction of the genes expected to have been present in its ancestor. Variation in the number of members of gene families present in the genome may contribute to the remarkable morphological plasticity of Brassica species. The B. rapa genome sequence provides an important resource for studying the evolution of polyploid genomes and underpins the genetic improvement of Brassica oil and vegetable crops.

Genetic diversity and population structure of the amylolytic yeast Saccharomycopsis fibuligera associated with Baijiu fermentation in China

Wang Ju-Wei,Han Pei-Jie,Han Da-Yong,Zhou Sen,Li Kuan,He Peng-Yu,Zhen Pan,Yu Hui-Xin,Liang Zhen-Rong,Wang Xue-Wei,Bai Feng-Yan 한국미생물학회 2021 The journal of microbiology Vol.59 No.8

The amylolytic yeast Saccharomycopsis fibuligera is a predominant species in starters and the early fermentation stage of Chinese liquor (Baijiu). However, the genetic diversity of the species remains largely unknown. Here we sequenced the genomes of 97 S. fibuligera strains from different Chinese Baijiu companies. The genetic diversity and population structure of the strains were analyzed based on 1,133 orthologous genes and the whole genome single nucleotide polymorphisms (SNPs). Four main lineages were recognized. One lineage contains 60 Chinese strains which are exclusively homozygous with relatively small genome sizes (18.55–18.72 Mb) and low sequence diversity. The strains clustered in the other three lineages are heterozygous with larger genomes (21.85–23.72 Mb) and higher sequence diversity. The genomes of the homozygous strains showed nearly 100% coverage with the genome of the reference strain KPH12 and the sub-genome A of the hybrid strain KJJ81 at the above 98% sequence identity level. The genomes of the heterozygous strains showed nearly 80% coverage with both the sub-genome A and the whole genome of KJJ81, suggesting that the Chinese heterozygous strains are also hybrids with nearly 20% genomes from an unidentified source. Eighty-three genes were found to show significant copy number variation between different lineages. However, remarkable lineage specific variations in glucoamylase and α-amylase activities and growth profiles in different carbon sources and under different environmental conditions were not observed, though strains exhibiting relatively high glucoamylase activity were mainly found from the homozygous lineage.

A King Stifling Voices of Dissent? Popular Protests and State Responses in Xi's China

Wang Hsin‐Hsien,Tzeng Wei‐Feng,Wang Shinn‐Shyr,Chiu Wei‐Chih 인하대학교 국제관계연구소 2021 Pacific Focus Vol.36 No.1

To deal with the increases in the frequency of popular protests, China's leader, Xi Jinping, has called for “innovative social governance” as a new concept to resolve social conflicts. In this study, we collect and analyze a unique dataset to compare state responses to popular protests during Xi's term and Hu's term. We find that, under Xi's rule, state repression is more frequently employed to handle social disturbances. Violent protests are significantly more likely to be repressed than nonviolent protests during both the rule of Hu and Xi, while protests that involved a population of the middle and upper classes experienced more state crackdown under Xi's rule rather than under Hu's governance. Our empirical analysis suggests that the approaches by which the Chinese government deals with social unrest have not yet been “innovative.” Instead, China still relies heavily on despotic power in the Xi era.

Geometric Optimization of a Mathematical Model of Radiofrequency Ablation in Hepatic Carcinoma

Wang, Kai-Feng,Pan, Wei,Wang, Fei,Wang, Gao-Feng,Madhava, Pai,Pan, Hong-Ming,Kong, De-Xing,Liu, Xiang-Guan Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.10

Radio frequency ablation (RFA) is an effective means of achieving local control of liver cancer. It is a particularly suitable mode of therapy for small and favorably located tumors. However, local progression rates are substantially higher for large tumors (>3.0 cm). In the current study, we report on a mathematical model based on geometric optimization to treat large liver tumors. A database of mathematical models relevant to the configuration of liver cancer was also established. The specific placement of electrodes and the frequency of ablation were also optimized. In addition, three types of liver cancer lesion were simulated by computer guidance incorporating mathematical models. This approach can be expected to provide a more effective and rationale mechanism for employing RFA in the therapy of hepatic carcinoma.

Study on mechanical behaviors of large diameter shield tunnel during assembling

Feng, Kun,Peng, Zuzhao,Wang, Chuang,He, Chuan,Wang, Qianshen,Wang, Wei,Cao, Songyu,Wang, Shimin,Zhang, Haihua Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.5

In order to study the mechanical behavior of shield tunnel segments during assembly stage, the in-situ tests and FDM numerical simulation were conducted based on the Foguan Shiziyang Tunnel with large cross-section. Analysis for the load state of the assembling segments in different assembly steps as well as the investigation for the changing of inner forces and longitudinal stress of segments with assembling steps were carried out in this paper. By comparing the tested results with the simulated results, the conclusions and suggestions could be drawn as follows: (1) It is the most significant for the effects on axial force and bending moment caused by the assembly of adjacent segment, followed by the insertion of key segment while the effects in the other assembly steps are relative smaller. With the increasing value of axial force, the negative bending moment turns into positive and remains increasing in most monitored sections, while the bending moment of segment B1and B6 are negative and keeping increasing; (2) The closer the monitored section to the adjacent segments or the key segment, the more significant the internal forces response, and the monitored effects of key segment insertion are more obvious than that of calculation; (3) The axial forces are all in compression during assembling and the monitored values are about 1.5~1.75 times larger than the calculated values, and the monitored values of bending moment are about 2 times the numerical calculation. The bending moment is more sensitive to the segments assembly process compared with axial force, and it will result in the large bending moment of segments during assembling when the construction parameters are not suitable or the assembly error is too large. However, the internal forces in assembly stage are less than those in normal service stage; (4) The distribution of longitudinal stress has strong influence on the changing of the internal forces. The segment side surface and intrados in the middle of two adjacent jacks are the crack-sensitive positions in the early assembly stage, and subsequently segment corners far away from the jacks become the crack-sensitive parts either.

2022 Taiwan clinical multicenter expert consensus and recommendations for thyroid radiofrequency ablation

Wei-Che Lin,Wen-Chieh Chen,Pei-Wen Wang,Yi-Chia Chan,Yen-Hsiang Chang,Harn-Shen Chen,Szu-Tah Chen,Wei-Chih Chen,Kai-Lun Cheng,Shun-Yu Chi,Pi-Ling Chiang,Chen-Kai Chou,Feng-Fu Chou,Shun-Chen Huang,Feng 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.3

Radiofrequency ablation (RFA) is a minimally invasive management strategy that has been widely applied for benign and recurrent malignant thyroid lesions as an alternative to surgery in Taiwan. Members of academic societies for specialists in interventional radiology, endocrinology, and endocrine surgery collaborated to develop the first consensus regarding thyroid RFA in Taiwan. The modified Delphi method was used to reach a consensus. Based on a comprehensive review of recent and valuable literature and expert opinions, the recommendations included indications, pre-procedural evaluations, procedural techniques, post-procedural monitoring, efficacy, and safety, providing a comprehensive review of the application of RFA. The consensus effectively consolidates advice regarding thyroid RFA in clinical practice for local experts.

Research of Automatically Generate Mapping Mechanism Based on the Semantic Role

Feng wang,Lei Cui,Yizhen Wang,Xinjiang Wei 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.10

Role based access control (RBAC) has been widely adopted in industrial and government. However RBAC is only suitable for closed enterprise environment. With modern Internet based application, collaboration and sharing among multiple organizations become essential and RBAC is no longer sufficient. Role mapping has been the solutions to deal with multiple domains, where the roles in the hierarchy of one organization are mapped to the roles in the hierarchy of another organization. But role mapping can be a tedious task for the security officers if it is done fully manually. Yet, performing role mapping automatically incur security risks. In this paper, we introduce a semi-automated role mapping process, where promising role mappings are generated automatically and recommended to the security officer(s). The security officers then approve or modify the recommended role mappings. We present a method for automatically generate role mappings based on the similarities of the roles in two role hierarchies. We use an example to illustrate our approach and show its feasibility.

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii in domestic rabbits (Oryctolagus cuniculus) in China

Qing-Feng Meng,Wei-Lin Wang,Xiao-Ting Ni,Hai-Bin Li,Gui-Zhe Yao,Xiao-Lin Sun,Wei-Li Wang,Wei Cong 대한기생충학열대의학회 2015 The Korean Journal of Parasitology Vol.53 No.6

The breeding of domestic rabbits (Oryctolagus cuniculus) for human consumption has a long tradition in China. Infections that can affect the production of meat or even be transmitted from animals to humans are important to monitor, especially for public health reasons as well as for their impact on animal health. Thus, a total of 1,132 domestic rabbit sera from 4 regions in China were collected for serological screening for Encephalitozoon cuniculi and for Toxoplasma gondii by ELISA and modified agglutination test (MAT), respectively. Antibodies to E. cuniculi were detected in 248/1,132 (21.9%) sera tested while antibodies against T. gondii revealed a seroprevalence of 51/1,132 (4.5%). We believe that the present results are of epidemiological implications and public health importance due to the acknowledged susceptibility of humans to E. cuniculi and T. gondii infections. Therefore, routine screening tests of domestic rabbits are proposed considering the zoonotic potential of these parasites.

MiR-21 Upregulation Induced by Promoter Zone Histone Acetylation is Associated with Chemoresistance to Gemcitabine and Enhanced Malignancy of Pancreatic Cancer Cells

Song, Wei-Feng,Wang, Lei,Huang, Wei-Yi,Cai, Xun,Cui, Jiu-Jie,Wang, Li-Wei Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Background and Aims: MicroRNA-21 (miR-21) is reported to be overexpressed and to contribute to proliferation, apoptosis and gemcitabine resistance in pancreatic ductal adenocarcinomas (PDACs). The aims of this study were to explore regulation of miR-21 expression by epigenetic change and its impact on chemoresistance and malignant properties of of pancreatic cancer. Materials and methods: We retrospectively collected 41 cases of advanced pancreatic cancer patients who were sensitive or resistant to gemcitabine and assessed levels of serum circulating miR-21 for correlation with cytotoxic activity. Histone acetylation in the miR-21 promoter was also studied in gemcitabine-sensitive and gemcitabine-resistant PDAC cells. Gemcitabine-resistant HPAC and PANC-1 cells were transfected with pre-miR-21 precursors (pre-miR-21) and antisense oligonucleotides (anti-miR-21), and were treated with TSA. Finally, invasion and metastasis assays were performed and alteration in mir-21, PTEN, AKT and pAKT level was evaluated in these cells. Results: Serum miR-21 levels were increased in gemcitabine-resistant PDAC patients compared with gemcitabine-sensitive subjects. The miR-21 levels were increased in 6 PDAC cells treated with gemcitabine significantly, associated with 50% inhibitory concentrations ($IC_{50}s$). Histone acetylation levels at miR-21 promoter were increased in PDAC cells after treatment with gemcitabine. Enhanced invasion and metastasis, increased miR-21 expression, decreased PTEN, elevated pAKT level were demonstrated in gemcitabine-resistant HPAC and PANC-1 cells. Pre-miR-21 transfection or TSA treatment further increased invasion and metastasis ability, decreased PTEN, and elevated pAKT levels in these two lines. In contrast, anti-miR-21 transfection could reverse invasion and metastasis, and PTEN and pAKT expressions induced by gemcitabine. Conclusions: MiR-21 upregulation induced by histone acetylation in the promoter zone is associated with chemoresistance to gemcitabine and enhanced malignant potential in pancreatic cancer cells.