Rational design of common transition metal-nitrogen-carbon catalysts for oxygen reduction reaction in fuel cells

Zheng, Yongping,Yang, Dae-Soo,Kweun, Joshua M.,Li, Chenzhe,Tan, Kui,Kong, Fantai,Liang, Chaoping,Chabal, Yves J.,Kim, Yoon Young,Cho, Maenghyo,Yu, Jong-Sung,Cho, Kyeongjae Elsevier 2016 Nano energy Vol.30 No.-

<P><B>Abstract</B></P> <P>Bio-inspired non-precious-metal catalysts based on iron and cobalt porphyrins are promising alternatives to replace costly platinum-based catalysts for oxygen reduction reaction (ORR) in fuel cells. However, the exact nature of the active sites is still not clearly understood, and further optimization design is needed for practical applications. Here, we report a rational catalyst design process by combining density functional theory (DFT) calculations and experimental validations. Two sets of square-planar (MN<SUB>x</SUB>C<SUB>4−x</SUB>) and square-pyramid (MN<SUB>x</SUB>C<SUB>5−x</SUB>) active centers (M=Mn, Fe, Co, Ni) incorporated in graphene were examined using DFT. Fe-N<SUB>5</SUB> and Co-N<SUB>4</SUB> sites were identified theoretically to have the best performance in fuel cells, while Ni-N<SUB>x</SUB>C<SUB>4−x</SUB> sites catalyze the most H<SUB>2</SUB>O<SUB>2</SUB> byproduct. Graphene samples with well-dispersed incorporations of metals were synthesized, and the following electrochemical measurements show an excellent agreement with the theoretical predictions, indicating that a successful design framework and systematic understanding toward the catalytic nature of these materials are established.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Graphene based catalysts design for ORR is demonstrated by combining experiments and modellings. </LI> <LI> Iron porphyrin like active site is unraveled to be five nitrogen coordinated as FeN<SUB>5</SUB>. </LI> <LI> Cobalt porphyrin like active site is shown to be four nitrogen coordinated as CoN<SUB>4</SUB>. </LI> <LI> Nickel porphyrin like catalyst is potentially used for catalytic synthesis of H<SUB>2</SUB>O<SUB>2</SUB>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Using TiO₂ Mesoflower Interlayer in Tubular Porous Titanium Membranes for Enhanced Electrocatalytic Filtration

Li, X.,Liu, G.,Shi, M.,Li, J.,Li, J.,Guo, C.,Lee, J.K.,Zheng, J. Pergamon Press 2016 ELECTROCHIMICA ACTA Vol.218 No.-

The current study focuses on synthesis and characterization of novel functionalized anodic membranes for wastewater treatment. This membrane was prepared by first constructing a TiO<SUB>2</SUB> mesoflower interlayer on a tubular porous titanium membrane and subsequently coating an antimony-doped tin oxide catalytic layer. Physical and electrochemical characterizations of the membranes were evaluated. With TiO<SUB>2</SUB> mesoflower, the membrane anode obtained a higher oxygen evolution potential, 2.22V (vs saturated calomel electrode), relative roughness factor (701.7), and electrochemical porosity (99.23%) than membrane anodes without TiO<SUB>2</SUB> mesoflower. The prepared membrane anode also achieved a low charge-transfer (0.11Ω) and mass-transfer resistance (0.21Ω) in filtration mode. The unique features were found linked to its 3-D porous and open structure, and formation of a Ti<SUB>0.2</SUB>Sn<SUB>0.8</SUB>O<SUB>2</SUB> sosoloid that had a high surface oxygen (O<SUB>ad</SUB>) content. The electrocatalytic filtration performance of this membrane was also tested using methyl orange as a model organic pollutant. At a current density of 15mAcm<SUP>-2</SUP>, the membrane achieved a higher 71.0% removal of methyl orange than 58.0% for the membrane without TiO<SUB>2</SUB> mesoflower. At a 58.0% removal of methyl orange, the membrane consumed a much lower energy of 0.20 kWh m<SUP>-3</SUP> than 5.88 kWh m<SUP>-3</SUP> for membrane anodes without TiO<SUB>2</SUB> mesoflower. The synthesized membrane electrode filter shows promise for future applications aimed to remove organic pollutants from wastewater.

New Evidence of Alleles (V199I and G52S) at the PRKAG3 (RN) Locus Affecting Pork Meat Quality

Chen, J.F.,Dai, L.H.,Peng, J.,Li, J.L.,Zheng, R.,Zuo, B.,Li, F.E.,Liu, M.,Yue, K.,Lei, M.G.,Xiong, Y.Z.,Deng, C.Y.,Jiang, S.W. Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.4

The porcine PRKAG3 (RN) gene encodes the regulatory gamma subunit of adenosine monophosphate-activated protein kinase (AMPK), which is a good candidate gene affecting meat quality. In this study, the effects of two missense mutations A595G (Ile199Val) and G154A (Gly52Ser) in porcine PRKAG3 gene on meat quality traits were studied in M. Longissimus dorsi (LD), M. Semispinalis capitis (SC) and M. Biceps femoris (BF) from different populations of 326 pigs. The PRKAG3 alleles 199I, 199IV, 52S and 52G were identified with PCR-RFLPs and all genotypes - 199I/199I, 199I/199V, 199V/199V, 52S/52S, 52S/52G and 52G/52G - were found. The frequency of V allele was larger than that of I allele in all populations. I allele frequency was zero in Chinese Meishan pigs (population D) especially. G allele frequency was larger than that of S allele in all populations except Large White (population A). Both variations at the PRKAG3 locus significantly affected these meat quality traits. The pork meat quality has not previously been established in Meishan or crosses thereof. The results suggested that generally pH of LD, SC and BF was higher in Meishan pigs than that in other populations. Moreover, Meishan pigs showed higher water-holding capacity and intramuscular fat (IMF), lower water content and water loss percentage compared to other populations in terms of the two variations. The results present here supply new evidence that alleles V199I and G52S at the PRKAG3 locus affect pork meat quality and provide useful information on pork production.

Organic composition of carbonaceous aerosols in an aged prescribed fire plume

Yan, B.,Zheng, M.,Hu, Y. T.,Lee, S.,Kim, H. K.,Russell, A. G. Copernicus GmbH 2008 Atmospheric Chemistry and Physics Vol.8 No.21

<P>Abstract. Aged smoke from a prescribed fire (dominated by conifers) impacted Atlanta, GA on 28 February 2007 and dramatically increased hourly ambient concentrations of PM2.5 and organic carbon (OC) up to 140 and 72 μg m−3, respectively. It was estimated that over 1 million residents were exposed to the smoky air lasting from the late afternoon to midnight. To better understand the processes impacting the aging of fire plumes, a detailed chemical speciation of carbonaceous aerosols was conducted by gas chromatography/mass spectrometry (GC/MS) analysis. Ambient concentrations of many organic species (levoglucosan, resin acids, retene, n-alkanes and n-alkanoic acids) associated with wood burning emission were significantly elevated on the event day. Levoglucosan increased by a factor of 10, while hopanes, steranes, cholesterol and major polycyclic aromatic hydrocarbons (PAHs) did not show obvious increases. Strong odd over even carbon number predominance was found for n-alkanes versus even over odd predominance for n-alkanoic acids. Alteration of resin acids during transport from burning sites to monitors is suggested by the observations. Our study also suggests that large quantities of biogenic volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) were released both as products of combustion and unburned vegetation heated by the fire. Higher leaf temperature can stimulate biogenic VOC and SVOC emissions, which enhanced formation of secondary organic aerosols (SOA) in the atmosphere. This is supported by elevated ambient concentrations of secondary organic tracers (dicarboxylic acids, 2-methyltetrols, pinonic acid and pinic acid). An approximate source profile was built for the aged fire plume to help better understand evolution of wood smoke emission and for use in source impact assessment. </P>

Mapping of Quantitative Trait Loci on Porcine Chromosome 7 Using Combined Data Analysis

Zuo, B.,Xiong, Y.Z.,Su, Y.H.,Deng, C.Y.,Lei, M.G.,Zheng, R.,Jiang, S.W.,Li, F.E. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.10

To further investigate the regions on porcine chromosome 7 that are responsible for economically important traits, phenotypic data from a total of 287 F2 individuals were collected and analyzed from 1998 to 2000. All animals were genotyped for eight microsatellite loci spanning the length of chromosome 7. QTL analysis was performed using interval mapping under the line-cross model. A permutation test was used to establish significance levels associated with QTL effects. Observed QTL effects were (chromosomewide significance, position of maximum significance in centimorgans): Birth weight (<0.01, 3); Carcass length (<0.05, 80); Longissimus muscle area (<0.01, 69); Skin percentage (<0.01, 69); Bone percentage (<0.01, 74); Fat depths at shoulder (<0.05, 54);Mean fat depth (<0.05, 81); Moisture in m. Longissimus Dorsi (<0.05, 88). Additional evidence was also found which suggested QTL for dressing percentage and fat depths at buttock. This study offers confirmation of several QTL affecting growth and carcass traits on SSC7 and provides an important step in the search for the actual major genes involved in the traits of economic interest.

Development and validation of modified QuEChERS method coupled with LC–MS/MS for simultaneous determination of cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite in various types of honey and royal jelly

Zheng, Weijia,Park, Jin-A.,Abd El-Aty, A.M.,Kim, Seong-Kwan,Cho, Sang-Hyun,Choi, Jeong-min,Yi, Hee,Cho, Soo-Min,Ramadan, Amer,Jeong, Ji Hoon,Shim, Jae-Han,Shin, Ho-Chul Elsevier 2018 Journal of chromatography. B, Analytical technolog Vol.1072 No.-

<P><B>Abstract</B></P> <P>Over the past few decades, honey products have been polluted by different contaminants, such as pesticides, which are widely applied in agriculture. In this work, a modified EN – quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction method was developed for the simultaneous quantification of pesticide residues, including cymiazole, fipronil, coumaphos, fluvalinate, amitraz, and its metabolite 2,4-dimethylaniline (2,4-DMA), in four types of honey (acacia, wild, chestnut, and manuka) and royal jelly. Samples were buffered with 0.2M dibasic sodium phosphate (pH 9), and subsequently, acetonitrile was employed as the extraction solvent. A combination of primary secondary amine (PSA) and C18 sorbents was used for purification prior to liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI<SUP>+</SUP>/MS-MS) analysis. The estimated linearity measured at six concentration levels presented good correlation coefficients (<I>R<SUP>2</SUP> </I>)≥0.99. The recovery, calculated from three different spiking levels, was 62.06–108.79% in honey and 67.58–106.34% in royal jelly, with an RSD<12% for all the tested compounds. The matrix effect was also evaluated, and most of the analytes presented signal enhancement. The limits of quantification (LOQ) ranged between 0.001 and 0.005mg/kg in various samples. These are considerably lower than the maximum residue limits (MRL) set by various regulatory authorities. A total of 43 market (domestic and imported) samples were assayed for method application. Among the tested samples, three samples were tested positive (i.e. detected and quantified) only for cymiazole residues. The residues in the rest of the samples were detected but not quantified. We concluded that the protocol developed in this work is simple and versatile for the routine quantification of cymiazole, 2,4-DMA, fipronil, coumaphos, amitraz, and fluvalinate in various types of honey and royal jelly.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Six pesticide residues in four types of honey and royal jelly were determined by LC–MS/MS analysis. </LI> <LI> Samples were extracted by a modified EN-QuEChERS method using both C18 sorbent and PSA. </LI> <LI> Recovery was good when the honey samples were extracted with 0.2M dibasic sodium phosphate buffer and acetonitrile. </LI> <LI> Three of the market samples tested positive for cymiazole residues. </LI> </UL> </P>

PKCβII inhibits the ubiquitination of β-arrestin2 in an autophosphorylation-dependent manner

Zheng, M.,Zhang, X.,Guo, S.,Zhang, X.,Choi, H.J.,Lee, M.Y.,Kim, K.M. North-Holland Pub ; Elsevier Science Ltd 2015 FEBS letters Vol.589 No.24

GPCR kinase 2 (GRK2)/β-arrestins and protein kinase A (PKA)/protein kinase C (PKC) mediate homologous and heterologous regulations of GPCRs, respectively. Conventional protein kinase C enzymes (PKCs), as exemplified by PKCβII, selectively inhibit internalization of dopamine D<SUB>2</SUB> receptor and β<SUB>2</SUB> adrenoceptor in a β-arrestin- but not GRK2-dependent manner. PKCβII interacts with β-arrestin2 upon autophosphorylation at T250, and inhibits the receptor internalization by decreasing the ubiquitination of β-arrestin2. PKCβII interferes with the interaction between β-arrestin2 and MDM2 in the cytosol, resulting in the redistribution of MDM2 to the nucleus. Subsequently, deubiquitination of β-arrestin2 and inhibition of agonist-induced receptor internalization follow. Thus, our study suggests that the extent of β-arrestin ubiquitination and the autophosphorylation status of PKCs determine PKCβII-mediated inhibition of homologous regulatory processes of GPCRs.

In Vitro Osteoblast Differentiation is Negatively Regulated by Hoxc8

Zheng, Y. J.,Chung, H. J.,Min, H.,Kang, M.,Kim, S. H.,Gadi, J.,Kim, M. H. HUMANA PRESS INC 2010 Applied biochemistry and biotechnology Vol.160 No.3

PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

Zheng, W.,Shen, R. F.,Sakamoto, T.,Beardmore, A. P.,De Pasquale, M.,Wu, X. F.,Gorosabel, J.,Urata, Y.,Sugita, S.,Zhang, B.,Pozanenko, A.,Nissinen, M.,Sahu, D. K.,Im, M.,Ukwatta, T. N.,Andreev, M.,Klun IOP Publishing 2012 The Astrophysical journal Vol.751 No.2

<P>We present a comprehensive analysis of a bright, long-duration (T-90 similar to 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the gamma-ray band, with optical light curve showing correlation with gamma-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to gamma-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (similar to 1100 s), a bright (R = 14.0) optical emission hump with very steep rise (alpha similar to 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R-GRB similar to 3 x 10(13) cm), initial Lorentz factor of the outflow (Gamma(0) similar to 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.</P>

Comparison of Axi-symmetric Single-Hole Nozzle with Multi-Hole Sac Nozzles

( M. C. Lai ),( Y. Zheng ),( X. Xie ),( K. Im ),( S. Moon ),( Z. Liu ),( J. Gao ),( J. Wang ),( J. M. Shi ),( R. E. Winsor ) 한국액체미립화학회 2010 한국액체미립화학회 학술강연회 논문집 Vol.2010 No.-

It is well know that the internal flow field and nozzle geometry affect the spray behavior, but without high-speed microscopic visualization, it is difficult to characterize the spray structure in details. Single-hole Diesel injectors have been used in fundamental spray research, while most direct-injection engines use multi-hole nozzle to tailor the fuel spray to the combustion chamber geometry. Recent engine trends also use smaller orifice and higher injection pressure. This paper discussed the quasi-steady near-nozzle Diesel spray structures of an axisymmetric single-hole nozzle and a symmetric two-hole nozzle configuration, with a nominal nozzle size of 130 ㎛. Both nozzle holes originate from a sac of identical geometry, but different flow structure inside the nozzle cause significant difference in the observed flow structure near the nozzle exit. The ultrafast fast Phase-contrast X-ray images revealed unique surface and internal morphology of the fuel sprays that can be identified. The two-hole nozzle produces much more unstable jet structure under same injection conditions. The early wavelength developed in the jet is measured to be 30~80 ㎛, depending on the injection conditions. The differences between the nozzle configurations are investigated using CFD simulation. The results show that the three-dimensional fluid flow entering the two-hole nozzle generates stronger streamline curvature and stream-wise vortices which are by default absent in the axisymmetric single-hole nozzle. It also produces thicker shear layer and higher turbulence. The interactions of downwash entrance flow with turbulence potentially enhance the instability and produce wider spray cone angles. The number of holes also has interesting effects on the strength of the vortices and the downwash.