Thermally crosslinked sulfonated polybenzimidazole membranes and their performance in high temperature polymer electrolyte fuel cells

Nambi Krishnan, N.,Konovalova, Anastasiia,Aili, David,Li, Qingfeng,Park, Hyun Seo,Jang, Jong Hyun,Kim, Hyoung-Juhn,Henkensmeier, Dirk Elsevier 2019 Journal of membrane science Vol.588 No.-

<P><B>Abstract</B></P> <P>The degradation pathway of phosphoric acid doped polybenzimidazole membranes in high temperature polymer electrolyte membrane fuel cells depends on the acid contents. If it is high, creep is discussed as the main reason. If it is low (membranes prepared by solvent evaporation and post-doping), the main cause may be loss of acid due to evaporation. The net transport of acid to the anode side at high current densities should also lead to local softening of the membrane, which could be mitigated by crosslinking the membrane.</P> <P>Here we show that sulfonated <I>para</I>-polybenzimidazole membranes can be stabilized by curing at 350 °C. In contrast to <I>meta</I>-polybenzimidazole and sulfonated <I>para</I>-polybenzimidazole, crosslinked sulfonated <I>para</I>-polybenzimidazole is insoluble in dimethylacetamide at room temperature and phosphoric acid at 160 °C. At 160 °C and 5% relative humidity the conductivity of crosslinked sulfonated <I>para</I>-polybenzimidazole and <I>meta</I>-polybenzimidazole is 214 mS cm<SUP>−1</SUP> and 147 mS cm<SUP>−1</SUP>, respectively. At 600 mA cm<SUP>−</SUP> <SUP>2</SUP>, the voltage decay rate is 16 μV h<SUP>−1</SUP>, much lower than published for commercial <I>meta</I>-polybenzimidazole (308 μV h<SUP>−1</SUP>). Furthermore, the average voltage at 600 mA cm<SUP>−</SUP> <SUP>2</SUP> is 523 mV, while a previously published cured <I>meta</I>-polybenzimidazole membrane only reaches 475 mV.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfonated <I>para</I>-PBI is covalently crosslinked by heating. </LI> <LI> Membranes are stable in DMAc at 27 °C and in 85 wt% phosphoric acid at 160 °C. </LI> <LI> Non-crosslinked sulfonated <I>para</I>-PBI and <I>meta</I>-PBI dissolve under these conditions. </LI> <LI> Conductivity is 44% higher than for <I>meta</I>-PBI. </LI> <LI> Fuel cell performance is stable; test time was 2100 h, half of that at 600 mA/cm<SUP>2</SUP> </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Involvement of GRP78 in the Resistance of Ovarian Carcinoma Cells to Paclitaxel

Zhang, Li-Ying,Li, Pei-Ling,Xu, Aili,Zhang, Xin-Chen Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.8

Background: Glucose regulated protein 78 (GRP78) is a type of molecular chaperone. It is a possible candidate protein that contributes to development of drug resistance. We first examined the involvement of GRP78 in chemotherapy-resistance in human ovarian cancer cell. Materials and Methods: The expression of GRP78 mRNA and protein were examined by RT-PCR and western blotting, respectively, in human ovarian cancer cells line (HO-8910). Sensitivity of HO-8910 to paclitaxel was determined with methyl thiazolyl tetrazolium (MTT). Suppression of GRP78 expression was performed using specific small-interfering RNA (siRNA) in HO-8910 cells, and cell apoptosis was assessed by flow cytometry. Statistical analysis was performed using the SPSS 15.0 statistical package. Results: HO-8910 cells, with high basal levels of GRP78, exhibited low sensitivity to paclitaxel. The mRNA and protein levels of GRP78 were dramatically decreased at 24h, 48h and 72h after transfection and the sensitivity to paclitaxel was increased when the GRP78 gene was disturbed by specific siRNA transfection. Conclusions: The results suggested that high GRP78 expression might be one of the molecular mechanisms causing resistance to paclitaxel, and therefore siRNA of GRP78 may be useful in tumor-specific gene therapy for ovarian cancer.

Overexpression of ARO10 in pdc5ΔMutant Resulted in Higher Isobutanol Titers in Saccharomyces cerevisiae

Jingzhi Li,Ruiqi Feng,Zhihui Wen,Aili Zhang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4

To investigate effects of different pyruvate decarboxylases on isobutanol titers in Saccharomyces cerevisiae, single-gene deletion of the three PDCs genes encoding pyruvate decarboxylases were constructed in this study. In addition, we over-expressed Ilv2, which catalyzed the first step in the valine synthetic pathway, and Bat2, which was the cytoplasmic branched-chain amino-acid aminotransferase that catalyzed L-valine to 2-ketoisovalerate, to increase isobutanol production in the genetically modified strains. Our results showed that knockout of PDC5 were one of the main factors among the three PDC genes for improving isobutanol titers in S. cerevisiae. Additionally, we found that deletion of PDC5 in strain carrying overexpressed ILV2 and ARO10 resulted in 8-fold higher isobutanol productivity as compared to the control strain in micro-aerobic fermentations. Our results also suggested that engineered strain pdc5ΔpILV2 pARO10 generated lower ethanol titers and higher acetate acid titers than the control strain, while the growth rate and glucose consumption rate of engineered strain pdc5ΔpILV2 pARO10 were slightly lower than that of the control strain. Meanwhile, the biomass concentration of pdc5ΔpILV2 pARO10 decreased dramatically than that of the control strain.

Conversion of Lignin-Nanofibers to CNFs

Ma Aili,Zhou Li,Chang Jie 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.6

In this study, a novel method, electrospinning, was used to prepare lignin-based carbon nanofibers. The major material was lignin. The chemical and thermal properties of different lignins were characterized to determine their suitability for partial incorporation of polyacrylonitrile (PAN). Then the precursor fibers were carbonized at a temperature from 600℃ to 1000℃, respectively to prepare biomass-based carbon nanofibers. The influences of carbonization temperature on prepared carbon nanofibers were investigated by X-ray diffraction (XRD), Raman, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results indicated that the diameter of prepared precursor fibers and carbon fibers were about 200 nm and 100 nm, respectively. The increase of temperature has little influence on the carbon fiber graphitization degree. The D band of the carbon fibers carbonized at 900℃ is lowest. The thermal stability of the carbon fibers changes little with rising temperature when carbonized temperature exceeds 900℃, and carbon fibers carbonized under 900℃ have most compact structure. Therefore, the above conclusions make clearly that 900℃ is the optimal carbonization temperature for preparing lignin-based carbon nanofibers in this technique. Meanwhile, the study is a doubled-edged enterprise that aims to recycle the waste from pulping industry as well as to turn it into a valuable material.

A High Spectral Efficiency CDMA System Based on Expanded Generalized Complementary Orthogonal Code Groups

Peijian Zhang,Aili Qu,Gengxin Sun,Fengjing Shao,Xing Yang,Daoben Li 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.6

A new CDMA system which uses fractional chip shift expanded generalized complementary orthogonal code groups as spectrum spreading code sequences and offer high spectral efficiency is introduced in the paper. This new CDMA system is totally different with conventional CDMA system in access codes designing and spectrum spreading process. In this CDMA system, the access codes of different cells keep orthogonality, which eliminates inter cells interferences (ACI) by aperiodic cross-correlation function (CCF). The spreading process of new CDMA system introduces inter symbols interference like overlap time division multiplexing (OVTDM) deliberately so as to improve spectral efficiency. The construction of expanded generalized complementary orthogonal code groups, shift method, principle of new CDMA system are explained respectively. Analysis and simulation results verify the validity of this new CDMA system.

Over expression of the wheat BEL1-like gene TaqSH1 affects floral organ abscission in Arabidopsis thaliana

Lan Zhang,Danmei Liu,Di Wang,Rongzhi Zhang,Shuaifeng Geng,Liang Wu,Aili Li,Long Mao 한국식물학회 2013 Journal of Plant Biology Vol.56 No.2

Seed shattering is one of the major domestication traits of crops. In wheat, except for the Q gene whose mutation renders free threshing and changing of rachis fragility, not much is known about the molecular mechanism for this process. We report here the cloning and characterization of TaqSH1, the ortholog of the rice seed shattering gene qSH1. TaqSH1 encodes a BEL1-like protein that is conserved between monocots and eudicots. TaqSH1 was located on the homoeologous group 3, a potential new genetic locus for seed threshability in wheat. Over expression of TaqSH1 in Arabidopsis resulted in dwarfed plants. The inflorescences of transgenic plants were more compact with larger pedicel angles. Scanning Electron Microscopy (SEM) showed that the transgenic siliques had a narrower replum where the dehiscence zone was altered. In addition, abscission of petals was significantly delayed due to delayed abscission zone development. Real-time PCR assays showed that over expression of TaqSH1 down regulated known Arabidopsis abscission related genes IDA, HAESA, KNAT1/6 and SHP1/2 in the transgenic plants. Taken together, our data suggest that TaqSH1 may represent another example of conserved mechanisms across monocots and eudicots for fruit/grain abscission and should have potential application in genetic manipulation of wheat seed shattering.

Characterization of Squamosa Promoter Binding Protein-LIKE genes in wheat

Bingnan Wang,Shuaifeng Geng,Di Wang,Nan Feng,Dongdong Zhang,Liang Wu,Chenyang Hao,Xueyong Zhang,Aili Li,Long Mao 한국식물학회 2015 Journal of Plant Biology Vol.58 No.4

Common wheat (Triticum aestivum) is an allohexaploid (AABBDD), with Triticum urartu (AA) and Aegilops tauschii (DD) as its A and D genome donors. Squamosa Promoter Binding Protein-Like (SPL) genes play important roles in plant development; however, a systematic study of this gene family in wheat is still lacking. Here, we mined the wheat genomes for SPLs and found 19 SPL genes each from the T. urartu and Ae. tauschii genomes. We also identified 58 SPL genes from the hexaploid wheat genome. We then compared the conservation and divergence of SPLs between the two diploid species in gene structures, tissuespecific expression patterns and responses to salt stress, drought and low temperature. For functional studies, two hexaploid wheat SPLs, TaSPL3 (with miR156 site mutated) and TaSPL6, were overexpressed in Arabidopsis and found to be involved in flowering time and biomass accumulation. In addition, a mutant allele (TaSPL6-D R ) with a 47 bp duplication upstream of the SBP domain was found to be associated with maturity date and grain number per spike among landraces from a Chinese wheat mini-core collection. Collectively, our work provides useful knowledge on the sequences and functions of wheat SPL genes that may help future functional studies and molecular breeding.

High-Throughput Sequencing Reveals Bacterial Diversity in Raw Milk Production Environment and Production Chain in Tangshan City of China

Huihui Cao,Yanhua Yan,Lei Wang,Lixue Dong,Xueliang Pang,Sining Tang,Aijun Li,Aili Xiang,Litian Zhang,Baiqin Zheng 한국축산식품학회 2021 한국축산식품학회지 Vol.41 No.3

Raw milk is a nature media of microbiota that access milk from various sources, which constitutes a challenge in dairy production. This study characterizes the relationship between the raw milk quality and the bacteria diversity at different sampling sites in dairy farms, aiming to provide a strong scientific basis for good hygienic practices and optimized procedure in milk production. High-throughput sequencing of 16S rRNA V3-V4 region was used to analyze the components, abundance and diversity of 48 bacterial population sampled from 8 different sites in dairy farm: pre-sterilized cow’s teats (C1), post-sterilized cow’s teats (C2), milking cluster (E), milk in storage tank (M1), transport vehicle (M2), storage equipment (E2), cow’s dung samples (F) and drinking water (W). Firmicutes account for predominantly 32.36% (C1), 44.62% (C2), 44.71% (E), 41.10% (M1), 45.08% (M2), 53.38% (F) of all annotated phyla. Proteobacteria accounts for 81.79% in W group and Actinobacteria 56.43% in E2 group. At the genus level, Acinetobacter was the most abundant genus that causes bovine mastitis, Acinetobacter and Arthrobacter were dominant in C1, C2, and E groups, Kocuria in E2 group and Arcobacter in W group. E, C1, and C2 group have very similar bacterial composition, and M1 and M2 demonstrated similar composition, indicating that the milking cluster was polluted by the environment or contact with cow udders. Bacterial population composition in different sampling sites identified by NGS reveals a correlation between the bacteria communities of raw milk production chain and the quality of raw milk.

Residual Stress Distribution in Hard-Facing of Pressure Relief Valve Seat

Ai, Li,Yu, Xinhai,Jiang, Wenchun,Woo, Wanchuck,Ze, Xiaofeng,Tu, Shan-Tung AMERICAN SOCIETY MECHANICAL ENGINEERS 2014 Journal of Pressure Vessel Technology Vol.136 No.6

<P>In this study, for the hard-facing of spring-loaded pressure relief valve seats, the residual stress distributions after the tungsten inert gas welding, (TIG) postwelded heat treatment and subsequent surface turning were investigated. The heat input parameters of welding were calibrated using an infrared imaging and thermocouples. The residual stress distributions were computed using three-dimensional finite element model. The neutron diffraction approach was employed to verify the finite element calculation. It is found that, the surface temperature during hard-facing welding shows a double ellipsoidal shape with the highest value of around 1570 degrees C. The high residual stress zones are located exactly under the welded joint except a slight deviation in the hoop direction. The magnitudes of tensile residual stresses in the three directions increase with their corresponding locations from the root of the joint into the base metal. The residual stresses in all of the three directions decrease significantly after the heat treatment. After surface turning, the residual stresses are tensile except for those close to the inner surface that are compressive in axial and radial directions.</P>