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Synthesis of a Novel Phosphorus-containing Flame Retardant for Epoxy Resins
Hong-Jun Xu,Fan-Long Jin,박수진 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.11
In this study, a novel phosphorus-containing flame retardant copolymer of spirocyclic pentaerythritol di(phosphate monochloride) and bisphenol S (SPD-BS) was successfully synthesized and used as a flame retardant in diglycidyl ether of bisphenol A (DGEBA) epoxy resins. The chemical structure of the SPD-BS was characterized using FT-IR and 1H NMR spectra. The thermal properties were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The effects of SPD-BS and nano-CaCO3 on the flame-retardant properties of DGEBA/SPD-BS systems were evaluated by measurement of the burning rate. As a result, the thermal stabilities of the DGEBA/SPD-BS systems were decreased with increasing SPD-BS content. The flame-retardant properties and char yields of the systems were significantly increased when SPD-BS content increased. The synergism of nano-CaCO3 incorporation on flame retardancy was found for the DGEBA/SPD-BS systems.
Research on the Optimization of the Performance of CTL Loop Discriminator
Xu Ying,Yuan Hong,Luo Ruidan,Xu Duo 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.5
Chip Tracking Loop (CTL) is the key to ensure the accuracy of regenerative pseudo-noise ranging in the deep space measurement and control communication system. However, due to the impact of the code imbalance, clock attenuation rate and noise, the loop locking time of CTL is prolonged and the ranging accuracy is degraded. In this paper, we proposed the discriminator optimization algorithm to address this problem. This algorithm is based on the loop discrimination performance of clock code and composite code, and the impact of the noise on the discrimination performance. In order to improve the tracking accuracy and shorten the loop locking time, this algorithm corrected the curve of discriminator’s gain by compensating discriminator’s gain. Both the theory analysis and simulation results illustrate that the algorithm can correct the discriminator’s gain curve, reduce the loop locking time and ensure the significant tracking accuracy in low SNR.
Hong Guang Xu,Jong Yul Roh,Jae Young Choi,Hee Jin Shim,Yong Wang,Qin Liu,Byung Rae Jin,Yeon Ho Je 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.05
Bt crystal proteins, encoded by cry genes, are a group of insecticidal proteins unique in the Gram-positive and spore-forming bacterium, Bacillus thuringiensis. These cry genes are widely applied as one of the most successful candidates for constructing transgenic plants resistant to pest insects. In our previous report, we found Cry1-5 had high insecticidal activity against Spodoptera larvae although its amino acid sequences showed high similarity (97.9%) to those of Cry1Ab which had low activity. In comparison with Cry1Ac, Cry1-5 had 12 different residues in domain Ⅰ and domain Ⅱ, and we focused on domain Ⅰand domain Ⅱ regions and designed 10 mutagenic primers to change 12 residues. Through multi site-directed mutagenesis, we mutated the modified cry1Ac gene by plant codon usage in pOBⅠ-Mod-cry1Ac based on cry1-5 and constructed 63 various mutant cry genes. In the further study, we will express those mutant proteins as a fusion form with polyhedrin using baculovirus expression system and subsequently do bioassay to Spodoptera larvae.
Synthesis of single azo disperse dye containing double ester and determination of crystal structure
Hong Xu,Zhengyu Zhang,Chunling Zheng 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.12
The synthesis, crystal structure analysis and characterization of a monoazo dye, 4-((2,6-dichloro-4-nitro phenyl)azo)-N-(diacetyl oxygen ethyl)aniline, are reported. The dye crystallised in the triclinic system, space group P-1 with a=8.1663(3) Å, b= 9.4222(3) Å, c=15.4694(5) Å, α=78.9130(10)o, β=75.019(2)o, γ =70.787(2)o, V=1078.26(6)Å3 and Z=2. There is only one molecule in the asymmetric unit. The dihedral angle between the two phenyl rings is 53.4 Å. In the crystal structure, intermolecular C-H…O hydrogen bonds link the molecules into centrosymmetric dimers,forming R22(30) ring motifs, in which they may be effective in the stabilization of the structure. Between the phenyl rings, the π…π stacking (interactions) may further stabilize the structure.
Hong Ting Tang,Jin Hou,Yu Shen,Lili Xu,Hui Yang,Xu Fang,Xiaoming Bao 한국미생물생명공학회(구 한국산업미생물학회) 2013 Journal of microbiology and biotechnology Vol.23 No.11
Bioethanol production from lignocellulose is considered as a sustainable biofuel supply. However, the low cellulose hydrolysis efficiency limits the cellulosic ethanol production. The cellulase is strongly inhibited by the major end product cellobiose, which can be relieved by the addition of β-glucosidase. In this study, three β-glucosidases from different organisms were respectively expressed in Saccharomyces cerevisiae and the β-glucosidase from Saccharomycopsis fibuligera showed the best activity (5.2 U/ml). The recombinant strain with S. fibuligera β-glucosidase could metabolize cellobiose with a specific growth rate similar to the control strain in glucose. This recombinant strain showed higher hydrolysis efficiency in the cellulose simultaneous saccharification and fermentation, when using the Trichoderma reesei cellulase, which is short of the β-glucosidase activity. The final ethanol concentration was 110% (using Avicel) and 89% (using acid-pretreated corncob) higher than the control strain. These results demonstrated the effect of β-glucosidase secretion in the recombinant S. cerevisiae for enhancing cellulosic ethanol conversion.
Hong Guang Xu,Jong Yul Roh,Jae Young Choi,Hee Jin Shim,Yong Wang,Qin Liu,Byung Rae Jin,Yeon Ho Je 한국응용곤충학회 2008 한국응용곤충학회 학술대회논문집 Vol.2008 No.10
Bt crystal proteins, encoded by cry genes, are a group of insecticidal proteins unique in the Gram-positive and spore-forming bacterium, Bacillus thuringiensis. These cry genes are widely applied as one of the most successful candidates for constructing transgenic crops resistant to pest insects. In our previous report, we found Cry1-5 had high insecticidal activity against Spodoptera larvae although its amino acid sequences showed high similarity (95.6%) to those of Cry1Ac which had low activity. In comparison with Cry1Ac, Cry1-5 had 12 different residues on domain I and II. In order to convert these residues to Cry1-5 randomly, 10 mutagenic primers were designed. Through multi site-directed mutagenesis, we mutated the modified cry1Ac gene by plant codon usage in pOBI-Modcry1Ac based on cry1-5 and constructed 63 mutant cry genes. Among them, 10 mutant cry genes on domain II were selected and their recombinant proteins were expressed by baculovirus expression system. From bioassay results to P. xylostella and S. exigua, we found some mutants have high insecticidal activities to be applicable to transgenic crops.
Application of artificial neural network for the critical flow prediction of discharge nozzle
Hong Xu,Tao Tang,Baorui Zhang,Yuechan Liu 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3
System thermal-hydraulic (STH) code is adopted for nuclear safety analysis. The critical flow model(CFM) is significant for the accuracy of STH simulation. To overcome the defects of current CFMs (lowprecision or long calculation time), a CFM based on a genetic neural network (GNN) has been developedin this work. To build a powerful model, besides the critical mass flux, the critical pressure and criticalquality were also considered in this model, which was seldom considered before. Comparing with thetraditional homogeneous equilibrium model (HEM) and the Moody model, the GNN model can predictthe critical mass flux with a higher accuracy (approximately 80% of results are within the ±20% errorlimit); comparing with the Leung model and the Shannak model for critical pressure prediction, the GNNmodel achieved the best results (more than 80% prediction results within the ±20% error limit). For thecritical quality, similar precision is achieved. The GNN-based CFM in this work is meaningful for the STHcode CFM development