Synthesis and Characterization of a Lateral Phthalonitrile Functionalized Main-Chain Polybenzoxazine Precursor

Jian Zheng,Yan Zhang,Ying Wang,Jianqun Gan,Lu Shen,FuBin Luo,Liyan Liang,Kun Wu,Mangeng Lu 한국고분자학회 2016 Macromolecular Research Vol.24 No.5

A lateral phthalonitrile functionalized main-chain polybenzoxazine precursor has been successfully synthesized. The structure was characterized by proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FTIR). The formation of benzoxazine rings were confirmed by the characteristic resonances observed at about 4.55 (C-CH2-N) and 5.30 ppm (N-CH2-O) and the absorbance at 950 cm-1 of benzene attached with an oxazine ring. The curing behavior was monitored by differential scanning calorimetry (DSC) and in situ FTIR. The completion of polymerization was proved by the disappearance of the band located at 950 cm-1 in FTIR. Thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the results indicated that the thermal stability of the cured polymer gained significant improvement than that without phthalonitrile functionalization.

Fucoxanthin Protects Cultured Human Keratinocytes against Oxidative Stress by Blocking Free Radicals and Inhibiting Apoptosis

( Jian Zheng ),( Mei Jing Piao ),( Young Sam Keum ),( Hye Sun Kim ),( Jin Won Hyun ) 한국응용약물학회 2013 Biomolecules & Therapeutics(구 응용약물학회지) Vol.21 No.4

Fucoxanthin is an important carotenoid derived from edible brown seaweeds and is used in indigenous herbal medicines. The aim of the present study was to examine the cytoprotective effects of fucoxanthin against hydrogen peroxide-induced cell damage. Fucoxanthin decreased the level of intracellular reactive oxygen species, as assessed by fl uorescence spectrometry performed after staining cultured human HaCaT keratinocytes with 2`,7`-dichlorodihydrofl uorescein diacetate. In addition, electron spin resonance spectrometry showed that fucoxanthin scavenged hydroxyl radical generated by the Fenton reaction in a cell-free system. Fucoxanthin also inhibited comet tail formation and phospho-histone H2A.X expression, suggesting that it prevents hydrogen peroxideinduced cellular DNA damage. Furthermore, the compound reduced the number of apoptotic bodies stained with Hoechst 33342, indicating that it protected keratinocytes against hydrogen peroxide-induced apoptotic cell death. Finally, fucoxanthin prevented the loss of mitochondrial membrane potential. These protective actions were accompanied by the down-regulation of apoptosispromoting mediators (i.e., B-cell lymphoma-2-associated x protein, caspase-9, and caspase-3) and the up-regulation of an apoptosis inhibitor (B-cell lymphoma-2). Taken together, the results of this study suggest that fucoxanthin defends keratinocytes against oxidative damage by scavenging ROS and inhibiting apoptosis.

Face Expression Recognition Based on Motion Templates and 4-layer Deep Learning Neural Network

Jianzheng Liu,Xiaojing Wang,Jucheng Yang,Chao Wu,Lijun Liu 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.12

A human facial expression is the formation of facial muscle movement. In our previous research, we proposed a method of identifying facial muscle movement which based on motion templates and GentleBoost. But the method was not robust enough to recognize human expression due to insufficient learning stage. So in this paper, we proposed a new method based on motion templates and 4-layer deep learning neural network to identify human's facial expressions. We recognized Action Unit as a kind of features by using motion templates and adaboost firstly, and then the extracted features were used to feed a 4-layer deep learning neural network to recognize the facial expression. The experimental results have proved that the proposed method can solve the problem encountered in our previous research.

Thermal and Mechanical Analysis of High-Power LEDs With Ceramic Packages

Jianzheng Hu,Lianqiao Yang,Moo Whan Shin IEEE 2008 IEEE Transactions on Device and Materials Reliabil Vol.8 No.2

<P>In this paper, we present the thermal and mechanical analysis of high-power light-emitting diodes (LEDs) with ceramic packages. Transient thermal measurements and thermomechanical simulations were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistances from the junction to the ambient were decreased from 79.6 to 46.7degC/W by replacing the plastic mold with a ceramic mold for LED packages. Thermomechanical stress induced in the heat-block test was simulated using a finite-element method. Higher level of thermomechanical stress in the chip was found for LEDs with ceramic packages, despite less mismatching coefficients of thermal expansion, compared with that with plastic packages. The thermomechanical-stress components in the direction of the thickness were found to be larger than that in other two directions. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high-power LEDs with ceramic packages is critically important and should be the reason for causing delaminating interface layers in the packages.</P>

Electrical, optical and thermal degradation of high power GaN/InGaN light-emitting diodes

Hu, Jianzheng,Yang, Lianqiao,Shin, Moo Whan Institute of Physics [etc.] 2008 Journal of physics. D, applied physics Vol.41 No.3

<P>The degradation of high power GaN/InGaN blue light-emitting diodes (LEDs) was investigated by considering the electrical, optical and thermal ageing characteristics. The LED samples were stressed at the elevated temperature of 85 °C with an injection current of 350 mA. Changes in the tunnelling current and series resistance for the electrical characteristics and an initial increase followed by a gradual decrease for the optical power were observed. Variations of the thermal resistance in the chip and package were found to be 2 °C W<SUP>−1</SUP> and 0.3 °C W<SUP>−1</SUP>, respectively. The responsible factors were proposed to be: (a) the dopant activation and changes of defects in the chip level; (b) the yellowing of the optical lens and structural degradations such as generating voids or delaminations in the package level. The changes in the electrical, optical and thermal characteristics were found to depend on and affect each other. The internal relationship for the characteristics of the three aspects was explained.</P>

Influence of Fe Addition on Microstructure and Properties of Cu-Ag Composite

Xiaowei Zuo,Jianzheng Zhu,Bailing An,Ke Han,Rui Li,Engang Wang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.5

We investigated the effects of Fe content on microstructure and properties in as-cast and as-drawn Cu-(5.1-x)vol%Ag-x vol%Fe alloys. In microscale, increasing Fe content first refined and then coarsened Cu dendrites. Innanoscale, the size and length of Ag precipitates in Fe-doped alloys were smaller than the size and length of Ag precipitatesin Fe-free alloy, and the γ-Fe precipitates in Cu-2.9 vol%Ag-2.4 vol%Fe alloy were finer than the γ-Feprecipitates in Cu-5.1 vol%Fe alloy. The maximum hardness in as-cast Cu-Ag-Fe alloys was found in the Cu-2.9vol%Ag-2.4 vol%Fe alloy. With increasing drawing strain, both ultimate tensile strength and hardness of Cu-Ag-Fe composites were increased. Simulation data among the relative volume fractions of Fe, hardness and electricalconductivity showed that, as the relative value approached 40%, the Cu-Ag-Fe composite displayed greater hardnessthan other samples. As a small amount of Ag was replaced by Fe, the electrical conductivity decreased significantlywith a descending slope of approximately 3%IACS (International Annealed Copper Standard) per vol%Fe. As 47 vol%Ag was replaced by Fe, however, the electrical conductivity decreased by 51% and remainedalmost invariable with further increasing Fe content. After annealing at 450 °C for 4 h, the electrical conductivityof the Cu-2.9 vol%Ag-2.4 vol%Fe composite was elevated up to 68.3%IACS from 38.5%IACS.

Butyric Acid Fermentation of Sodium Hydroxide Pretreated Rice Straw with Undefined Mixed Culture

( Binling Ai ),( Jianzheng Li ),( Xue Chi ),( Jia Meng ),( Chong Liu ),( En Shi ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.5

This study describes an alternative mixed culture fermentation technology to anaerobically convert lignocellulosic biomass into butyric acid, a valuable product with wide application, without supplementary cellulolytic enzymes. Rice straw was soaked in 1% NaOH solution to increase digestibility. Among the tested pretreatment conditions, soaking rice straw at 50°C for 72 h removed ~66% of the lignin, but retained ~84% of the cellulose and ~71% of the hemicellulose. By using an undefined cellulose-degrading butyrate-producing microbial community as butyric acid producer in batch fermentation, about 6 g/l of butyric acid was produced from the pretreated rice straw, which accounted for ~76% of the total volatile fatty acids. In the repeated-batch operation, the butyric acid production declined batch by batch, which was most possibly caused by the shift of microbial community structure monitored by denaturing gradient gel electrophoresis. In this study, batch operation was observed to be more suitable for butyric acid production.

A mixed culture performing nitrite-dependent anaerobic methane oxidation and the nitrite removal mechanism revealed by high-throughput sequencing

Han Yan,Jianzheng Li,Jia Meng,Xin Wang,Lianggang Tang,Avinash Kumar Jha 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.4

Nitrite-dependent anaerobic methane oxidation (n-DAMO) has been regarded as a promising effective approach to nitrogen removal from wastewater. However, n-DAMO bacteria are very difficult to be enriched in biological wastewater treatment processes. An anaerobic sequencing batch reactor (AnSBR) was introduced in the present study for the enrichment of n-DAMO bacteria with cornfield soil as inoculum. Fed with nitrite (NO₂<SUP>−</SUP>) and methane as the specific substrates, a NO₂<SUP>−</SUP> load removal as high as 46.16 mg/(L·d) was obtained in the AnSBR since the 232<SUP>nd</SUP> day of enrichment culturing, though the relative abundance of Candidatus Methylomirabilis referring to n-DAMO bacteria was 2.37% in the acclimatized mixed culture. High-throughput sequencing of the obtained mixed culture revealed that the community structure was complex with the coexistence of n-DAMO bacteria, methanotrophs, heterotrophic denitrifying bacteria and hydrolytic fermentation bacteria. Analysis of interactions among the prevalent microbial populations suggested that Candidatus Methylomirabilis had played a key role in the metabolic network of the mixed culture. The research work presented a novel approach to the enrichment of n-DAMO bacteria from cornfield soil and was helpful in understanding the role of n-DAMO bacteria in complex matrices.

Effect of pH and Buffer on Butyric Acid Production and Microbial Community Characteristics in Bioconversion of Rice Straw with Undefined Mixed Culture

Binling Ai,Jianzheng Li,Xue Chi,Jia Meng,Ajay Kumar Jha,Chong Liu,En shi 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.4

This study was conducted to identify theoptimum pH range and the appropriate buffer for butyricacid production from rice straw by fermentation using anundefined mixed culture. A series of experiments conductedat pH levels of 5.0 ~ 7.0 showed that neutral pH improvedrice straw conversion and consequently carboxylic acidproduction. The highest butyric acid production (up to6.7 g/L) was achieved at pH of 6.0 ~ 6.5, while it was only1.7 g/L without pH control or at pH 5.0. Another series ofexperiments conducted at pH 6.0 ~ 6.5 buffered withCaCO3, NaHCO3, NH4HCO3 and their combinationsindicated that different buffers had different effects ontheproduct spectrum, and that CaCO3 combined with NaHCO3was an effective buffer for butyric acid production. Thehighest total volatile fatty acids (about 12.6 g/L) productionand one of the two highest butyric acid concentrations(about 7.6 g/L) were obtained by buffering with CaCO3combined with NaHCO3. PCR-DGGE analysis revealedthat different pH and buffers also influenced the microbialpopulation distribution. Bacteria were suppressed at lowpH , while the bacterial community structures at higher pHvaried slightly. Overall, this study presents an alternativemethod for butyric acid production from lignocellulosicbiomass without supplementary cellulolytic enzyme.

Response of Syntrophic Propionate Degradation to pH Decrease and Microbial Community Shifts in an UASB Reactor

( Liguo Zhang ),( Qiaoying Ban ),( Jianzheng Li ),( Ajay Kumar Jha ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.8

The effect of pH on propionate degradation in an upflow anaerobic sludge blanket (UASB) reactor containing propionate as a sole carbon source was studied. Under influent propionate of 2,000 mg/l and 35ºC, propionate removal at pH 7.5-6.8 was above 93.6%. Propionate conversion was significantly inhibited with stepwise pH decrease from pH 6.8 to 6.5, 6.0, 5.5, 5.0, 4.5, and then to 4.0. After long-term operation, the propionate removal at pH 6.5-4.5 maintained an efficiency of 88.5%-70.1%, whereas propionate was hardly decomposed at pH 4.0. Microbial composition analysis showed that propionate-oxidizing bacteria from the genera Pelotomaculum and Smithella likely existed in this system. They were significantly reduced at pH ≤5.5. The methanogens in this UASB reactor belonged to four genera: Methanobacterium, Methanospirillum, Methanofollis, and Methanosaeta. Most detectable hydrogenotrophic methanogens were able to grow at low pH conditions (pH 6.0-4.0), but the acetotrophic methanogens were reduced as pH decreased. These results indicated that propionate-oxidizing bacteria and acetotrophic methanogens were more sensitive to low pH (5.5-4.0) than hydrogenotrophic methanogens.