One-step synthesis of methylmethacrylate from methacrolein over Keggin-type heteropoly compounds

Xiaojun Guo,Chongpin Huang,Biaohua Chen 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

One-step synthesis of methylmethacrylate (MMA) using heteropoly compounds (HPCs) as catalysts was demonstrated by feeding a mixture of methacrolein (MAL), air, water, nitrogen and MeOH (methanol). The HPCs with different counter-ions, such as H1.7Cs1.5Cu0.25As0.1PMo11VO40 (CsPMo11VO40), H1.7La0.7Cu0.25As0.1PMo11VO40 (LaPMo11VO40) and H1.7K1.5Cu0.25As0.1PMo11VO40 (KPMo11VO40), were studied in oxidation of MAL, esterification of methacrylic acid (MAA) and one-step synthesis of MMA from MAL, respectively. The selectivity of MAA was up to 45.7% and MMA was 44.6% with 93.3% MAL conversion over CsPMo11VO40.

Effect of cesium content on the structure and catalytic performances of heteropoly compounds in one-step synthesis of methylmethacrylate from methacrolein

Xiaojun Guo,Chongpin Huang,Yingxia Li 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

Keggin-type heteropoly compounds (HPCs) H3.2−xCsxCu0.25As0.1PMo11VO40 (x, 0-2.5) were used as catalysts for coupling reaction of methylmethacrylate (MMA) from methacrolein (MAL) in this study. And the catalytic performance of the HPCs was investigated in the oxidation-esterification coupling reaction. Moreover, the HPCs were characterized by NH3-TPD, TG-pyridine-adsorption/desorption, N2-adsorption/desorption, ICP, TG-DSC, FT-IR, XRD and TPR. These reactive results have been correlated to the acidity, surface area and reducibility. With the increasing of Cs content, surface area of the HPCs increased, while the acidity and reducibility decreased. Difference of the quantity of acid sites originated from the hydration protons being substituted by Cs+. Effects of Cs+ content on the reducibility of the HPCs indicated that Cs+ changed the structural stability of V as coordinating atoms and the proportion of the different reducible states of Mo6+.

Novel splice isoforms of pig myoneurin and their diverse mRNA expression patterns

Guo, Xiaohong,Li, Meng,Gao, Pengfei,Cao, Guoqing,Cheng, Zhimin,Zhang, Wanfeng,Liu, Jianfeng,Liu, Xiaojun,Li, Bugao Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.10

Objective: The aim of this study was to clone alternative splicing isoforms of pig myoneurin (MYNN), predict the structure and function of coding protein, and study temporal and spatial expression characteristics of each transcript. Methods: Alternative splice isoforms of MYNN were identified using RNA sequencing (RNA-seq) and cloning techniques. Quantitative real-time polymerase chain reaction (qPCR) was employed to detect expression patterns in 11 tissues of Large White (LW) and Mashen (MS) pigs, and to study developmental expression patterns in cerebellum (CE), stomach (ST), and longissimus dorsi (LD). Results: The results showed that MYNN had two alternatively spliced isoforms, MYNN-1 (GenBank accession number: KY470829) and MYNN-2 (GenBank accession number: KY670835). MYNN-1 coding sequence (CDS) is composed of 1,830 bp encoding 609 AA, whereas MYNN-2 CDS is composed of 1,746 bp encoding 581 AA. MYNN-2 was 84 bp less than MYNN-1 and lacked the sixth exon. MYNN-2 was found to have one $C_2H_2$ type zinc finger protein domain less than MYNN-1. Two variants were ubiquitously expressed in all pig tissues, and there were significant differences in expression of different tissues (p<0.05; p<0.01). The expression of MYNN-1 was significantly higher than that of MYNN-2 in almost tissues (p<0.05; p<0.01), which testified that MYNN-1 is the main variant. The expression of two isoforms decreased gradually with increase of age in ST and CE of MS pig, whereas increased gradually in LW pig. In LD, the expression of two isoforms increased first and then decreased with increase of age in MS pig, and decreased gradually in LW pig. Conclusion: Two transcripts of pig MYNN were successfully cloned and MYNN-1 was main variant. MYNN was highly expressed in ST, CE, and LD, and their expression was regular. We speculated that MYNN plays important roles in digestion/absorption and skeletal muscle growth, whereas the specific mechanisms require further elucidation.

MIGRATION OF CHARGED SPECIES IN LIPID BILAYER MEMBRANES UNDER AN ELECTRIC FIELD

XIAOJUN HAN,Lei Wang,CHANGJUN GUO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.1

This paper reviews recent progress in studies on the migration of charged species, includingcharged lipids, membrane-attached proteins and vesicles, and integrated membrane proteins, inlipid bilayer membranes under an external electric field. The migration of these charged substancesis controlled by the interplay of electrophoresis and electroosmosis. This phenomenon canbe employed to separate the charged lipids and membrane-attached proteins, and concentrateintegrated membrane proteins.

Microstructure and Magnetic Properties of Plasma-Sprayed Fe<SUB>73.5</SUB>Cu1Nb₃Si<SUB>13.5</SUB>B₉ Coatings

Xiaojun Ni,Xihui Bo,Jiawei Wu,Jinhua Guo,Zhichao Lu,Shaoxiong Zhou 한국자기학회 2010 한국자기학회 학술연구발표회 논문개요집 Vol.2010 No.12

Matrix Channel Width Evolution of Single Crystal Superalloy Under Creep and Thermal Mechanical Fatigue: Experimental and Modeling Investigations

Zixu Guo,Ziyuan Song,Dawei Huang,Xiaojun Yan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.12

In this study, in the respect of rafting behavior of Ni-based single crystal (SC) superalloy under creep and thermal mechanicalfatigue (TMF), an image processing program is developed to investigate the probability characteristic of γ channel width, anda channel width evolution model considering non-quasi-static modification is proposed. Firstly, the fractured and interruptedtests are conducted on SC superalloy. The channel width evolution behavior under different load conditions is observed viascanning electron microscope. Then, an image processing program based on image binarization is developed to conductstatistics on channel width. The statistical results show that the stress and temperature have significant effects on raftingrate, while the phase difference has a small effect. Meanwhile, the channel width obeys lognormal distribution, and the meanvalues follow linear relationship with standard deviations. In the modeling part, a static model is established to predict themean value evolution of channel width under creep condition. To be generalized to TMF condition, the model is modifiedby considering the non-quasi-static effect. After that, the channel width evolution model is further derived to describe theprobability density distribution of channel width. The predicted channel width evolutions are in good agreement with theexperimental results. The statistical results and models can provide the basis for multiscale modeling of SC superalloy.

The Importance of Allergen Avoidance in High Risk Infants and Sensitized Patients: A Meta-analysis Study

Wu Huiyan,Guo Yuhe,Wang Juan,Zhang Junyan,Zhang Xiaojun,Tao Ailin 대한천식알레르기학회 2014 Allergy, Asthma & Immunology Research Vol.6 No.6

Purpose: At this time, there is uncertainty regarding whether allergen avoidance is the most appropriate strategy for managing or preventing allergies. The purpose of this study was to evaluate the effectiveness of allergen avoidance in the prevention of allergic symptoms in previously sensitized patients and newborns that have the potential to develop allergies. Methods: We performed online searches of articles published from January 1980 to December 2012 in PubMed and The Cochrane Central Register of Controlled Trials, and selected articles involving randomized controlled trials (RCTs) and allergen avoidance. The parameters used to determine allergenic potential in newborns included the risk ratio (RR) of eczema, asthma, rhinitis, wheeze, and cough. The methods employed to evaluate previously sensitized patients were the standardized mean difference (SMD) of forced expiratory volume in 1 second (FEV1) and peak expiratory flow rate (PEFR). Data quality was assessed using the Jadad scale. Results: A total of 14 RCTs were identified. Meta-analysis demonstrated that allergen avoidance for newborns did not reduce the subsequent incidence of allergic diseases (eczema, P=0.21; rhinitis, P=0.3; cough, P=0.1) but significantly reduced the incidence of asthma and wheezing in high-risk infants (asthma, P=0.03; wheeze, P=0.0004). However, previously sensitized patients who reduced their exposure to known allergens did not show improvement in their lung functions (FEV1, P=0.3; PEFR morning, P=0.53; PEFR evening, P= 0.2; PEFR, P=0.29). Conclusions: Allergen avoidance may not always be successful in preventing allergic symptoms. However, rigorous methodological studies are required to confirm this hypothesis.

The Application of Decellularized Adipose Tissue Promotes Wound Healing

Xia Zenan,Guo Xiao,Yu Nanze,Zeng Ang,Si Loubin,Long Fei,Zhang Wenchao,Wang Xiaojun,Zhu Lin,Liu Zhifei 한국조직공학과 재생의학회 2020 조직공학과 재생의학 Vol.17 No.6

Background: Due to adipose-derived stem cells (ASCs) being easy to obtain, their rapid proliferation rate, and their multidirectional differentiation capabilities, they have been widely used in the field of regenerative medicine. With the progress of decellularized adipose tissue (DAT) and adipose tissue engineering research, the role of DAT in promoting angiogenesis has gradually been emphasized. Methods: We examined the biological characteristics and biosafety of DAT and evaluated the stem cell maintenance ability and promotion of growth factor secretion through conducting in vitro and in vivo studies. Results The tested ASCs showed high rat:es of proliferation and adhered well to DAT. The expression levels of essential genes for cell stem maintenance, including OCT4, SOX2, and Nanog were low at 2–24 h and much higher at 48 and 96 h. The Adipogenic expression level of markers for ASCs proliferation including PPARγ, C/EPBα, and LPL increased from 2 to 96 h. Co-culture of ASCs and DAT increased the secretion of local growth factors, such as VEGF, PDGF-bb, bFGF, HGF, EGF, and FDGF-bb, and secretion gradually increased from 0 to 48 h. A model of full-thickness skin defects on the back of nude mice was established, and the co-culture of ASCs and DAT showed the best in vivo treatment effect. Conclusion: The application of DAT promotes wound healing, and DAT combined with ASCs may be a promising material in adipose tissue engineering and regenerative medicine.

Genome-wide identification and resistance expression analysis of the NBS gene family in Triticum urartu

Jing Liu,Linyi Qiao,Xiaojun Zhang,Xin Li,Haixian Zhan,Huijuan Guo,Jun Zheng,Zhijian Chang 한국유전학회 2017 Genes & Genomics Vol.39 No.6

As the largest class of resistant genes, the nucleotide binding site (NBS) has been studied extensively at a genome-wide level in rice, sorghum, maize, barley and hexaploid wheat. However, no such comprehensive analysis has been conducted of the NBS gene family in Triticum urartu, the donor of the A genome to the common wheat. Using a bioinformatics method, 463 NBS genes were isolated from the whole genome of T. urartu, of which 461 had location information. The expansion pattern and evolution of the 461 NBS candidate proteins were analyzed, and 118 of them were duplicated. By calculating the lengths of the copies, it was inferred that the NBS resistance gene family of T. urartu has experienced at least two duplication events. Expression analysis based on RNA-seq data found that 6 genes were differentially expressed among Tu38, Tu138 and Tu158 in response to Blumeria graminis f.sp.tritici (Bgt). Following Bgt infection, the expression levels of these genes were up-regulated. These results provide critical references for further identification and analysis of NBS family genes with important functions.

Multilevel resistive switching and synaptic behaviors in MnO-based memristor

Ai Ruibo,Zhang Tao,Guo Huijie,Luo Wang,Liu Xiaojun 한국물리학회 2022 Current Applied Physics Vol.41 No.-

Exploring new synaptic electronic devices that combine computing and memory is a promising strategy that fundamentally approaches intelligent machines. In this study, the multilevel resistive switching and synaptic behaviors of a MnO-based device is studied. The device is composed of Al/MnO/Ni sandwich structure, has stable resistance switching characteristics, has continuous nonvolatile memory state, can be used as electrically programmable and erasable analog memory. The gradual conductance modulation is realized by changing the compliance current and the maximum scanning voltage. The Al/MnO/Ni devices successfully mimic the basic functions of synapses, including the paired-pulse facilitation, spike-rate-dependent plasticity, excitatory postsynaptic current, short-term plasticity, long-term plasticity, and sike-timing-dependent plasticity.