USING WIDE SPECTRAL RANGE INFRARED SPECTROSCOPY TO OBTAIN BOTH SURFACE SPECIES AND CHANGES OF CATALYST ITSELF UNDER THE REACTION CONDITIONS

Fundamental understanding of catalysts under the reaction conditions is key for designing new catalysts, and improving catalysts and catalytic conversion processes. Such understanding can be achieved only by characterization of catalysts under the reaction conditions because catalyst structures and the mechanisms of catalytic reactions depend on the reaction environment. Raman spectroscopy is one of the few instrumental methods that in a single measurement can provide information about both solid catalysts and the molecules reacting on them. However, its sensitivities for the surface species and the surface changes under catalytic reaction are limited. Infrared spectroscopy is also a wide spectral range (6000-50 cm-1) technique that enables examination of the nature of molecular species, identification of solid phases. Unfortunately, most of the heterogeneous catalysts consist of oxides as the active components or as the supports, which strong IR adsorption (below 1200 cm-1) limits the in situ IR to measure only the surface species (4000~900 cm-1). In this presentation, we will present our new developments of in-situ infrared spectroscopies with a spectral range of 4000~400 cm-1, for both the reflection adsorption infrared spectroscopy (IRAS) and transparent infrared spectroscopy (FTIR, unpublished data), that are capable of measuring both the surface species and changes specific to the surface

The effect of the support on the surface composition of PtCu alloy nanocatalysts: In situ XPS and HS-LEIS studies

Pt是一类高效、稳定的催化剂, 但Pt资源短缺且价格昂贵, 限制了其广泛商业化应用. 合金化可以使Pt的用量大为减少,; 且往往能显著提高其催化性能, 因而广泛应用于多相催化和电催化. 其中PtCu合金是一类很有前景的催化剂, Cu资源丰富、价格低廉,; 不仅降低了成本, 而且由于合金效应提高了催化剂的活性和稳定性. 由于合金的粒径、形状、组成及结构是影响其催化性能的重要因素,; 目前研究大多关注这些特征的可控合成.然而, 大多工业金属催化剂都是负载于氧化物上以提高催化性能,; 合金纳米粒子的形貌以及表面组成因与载体作用而发生改变, 也就是所谓的载体效应. 这体现在金属/氧化物界面处,; 能够促进金属粒子分散、改变其形貌甚至化学态、进而改变其催化性能, 其中最具代表性的金属-载体强相互作用. 因此,; 研究不同氧化物载体上合金催化剂的分散度、表面组成、化学态, 特别是不同气氛的影响, 对明确影响催化剂性能的关键控制因素非常重要.; 但是由于多相催化剂的复杂性, 且表面灵敏的测试手段很少, 目前相关报道还不多.; 近年发展起来的高灵敏度低能离子散射谱(HS-LEIS)是表面层灵敏的测试技术,; 可以测定最表面层的组成和含量.本文采用溶剂热共还原法成功制备了均一单相、粒径分布较窄的PtCu_x合金纳米颗粒,; 并运用浸渍法将其负载在TiO_2载体上, 以保证载体上纳米粒子组成的均一性.; 应用准原位X-射线光电子能谱(XPS)和高HS-LEIS对负载的PtCu合金纳米催化剂在不同条件处理后的表面组成和化学状态进行表征,; 发现催化剂的表面组成、分布、形貌和化学状态显著受到载体和处理条件的影响, 同时得到负载和未负载的催化剂表面组成与体相组成关系的相图. 结果表明,; PtCu_x/TiO_2催化剂在连续氧化过程中, Cu被氧化并较好在载体表面铺展, Pt-Cu合金状态被破坏,; Pt可能主要形成单一金属的纳米粒子, 并在界面处形成Ptd+. 在连续还原过程中, 部分被还原的Cu, 与Pt形成富Pt合金粒子.; 催化剂表面层主要是Cu, Pt很少, 与体相组成有很大差别, 说明载体对Cu的分散起到重要作用.Supported PtCu alloys have been broadly applied in heterogeneous catalysis and electrocatalysis owing to their excellent catalytic performance and high CO tolerance. It is important to analyze the outermost surface composition of the supported alloy nanoparticles to understand the nature of the catalytically active sites. In this paper, homogeneous face-centered cubic PtCu nanoparticles with a narrow particle size distribution were successfully fabricated and dispersed on a high-surface-area TiO2 powder support. The samples were oxidized and reduced in situ and then introduced into the ultrahigh vacuum chamber to measure the topmost surface composition by high-sensitivity low-energy ion scattering spectroscopy, and to determine the oxidation states of the elements by X-ray photoelectron spectroscopy. The surface composition and morphology, elemental distribution, and oxidation states of the components were found to be significantly affected by the support and treatment conditions. The PtCu is de-alloyed upon oxidation with CuO wetting on the TiO2 surface and re-alloyed upon reduction. Phase diagrams of the surface composition and the bulk composition were plotted and compared for the supported and unsupported materials. (C) 2017, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.National Basic Research Program of China (973 Program) [2013CB933102];; National Natural Science Foundation of China [21273178, 21573180,; 91545204]; Xiamen-Zhuoyue Biomass Energy Co. Ltd

Development of TaqMan® MGB fluorescent real-time PCR assay for the detection of anatid herpesvirus 1

<p>Abstract</p> <p>Background</p> <p>Anatid herpesvirus 1 (AHV-1) is an alphaherpesvirus associated with latent infection and mortality in ducks and geese and is currently affecting the world-wide waterfowl production severely. Here we describe a fluorescent quantitative real-time PCR (FQ-PCR) method developed for fast measurement of AHV-1 DNA based on TaqMan MGB technology.</p> <p>Results</p> <p>The detection limit of the assay was 1 × 10¹standard DNA copies, with a sensitivity of 2 logs higher than that of the conventional gel-based PCR assay targeting the same gene. The real-time PCR was reproducible, as shown by satisfactory low intra-assay and inter-assay coefficients of variation.</p> <p>Conclusion</p> <p>The high sensitivity, specificity, simplicity and reproducibility of the AHV-1 fluorogenic PCR assay, combined with its wide dynamic range and high throughput, make this method suitable for a broad spectrum of AHV-1 etiologically related application.</p

Characterization of the duck enteritis virus UL55 protein

<p>Abstract</p> <p>Background</p> <p>Characteration of the newly identified duck enteritis virus UL55 gene product has not been reported yet. Knowledge of the protein UL55 can provide useful insights about its function.</p> <p>Results</p> <p>The newly identified duck enteritis virus UL55 gene was about 561 bp, it was amplified and digested for construction of a recombinant plasmid pET32a(+)/UL55 for expression in Escherichia coli. SDS-PAGE analysis revealed the recombinant protein UL55(pUL55) was overexpressed in Escherichia coli BL21 host cells after induction by 0.2 mM IPTG at 37°C for 4 h and aggregated as inclusion bodies. The denatured protein about 40 KDa named pUL55 was purified by washing five times, and used to immune rabbits for preparation of polyclonal antibody. The prepared polyclonal antibody against pUL55 was detected and determined by Agar immundiffusion and Neutralization test. The results of Wstern blotting assay and intracellular analysis revealed that pUL55 was expressed most abundantly during the late phase of replication and mainly distributed in cytoplasm in duck enteritis virus infected cells.</p> <p>Conclusions</p> <p>In this study, the duck enteritis virus UL55 protein was successfully expressed in prokaryotic expression system. Besides, we have prepared the polyclonal antibody against recombinant prtein UL55, and characterized some properties of the duck enteritis virus UL55 protein for the first time. The research will be useful for further functional analysis of this gene.</p

Expressing gK gene of duck enteritis virus guided by bioinformatics and its applied prospect in diagnosis

<p>Abstract</p> <p>Background</p> <p>Duck viral enteritis, which is caused by duck enteritis virus (DEV), causes significant economic losses in domestic and wild waterfowls because of the high mortality and low egg production rates. With the purpose of eliminating this disease and decreasing economic loss in the commercial duck industry, researching on glycoprotein K (gK) of DEV may be a new kind of method for preventing and curing this disease. Because glycoproteins project from the virus envelope as spikes and are directly involved in the host immune system and elicitation of the host immune responses, and also play an important role in mediating infection of target cells, the entry into cell for free virus and the maturation or egress of virus. The gK is one of the major envelope glycoproteins of DEV. However, little information correlated with gK is known, such as antigenic and functional characterization.</p> <p>Results</p> <p>Bioinformatic predictions revealed that the expression of the full-length gK gene (<it>fgK</it>) in a prokaryotic system is difficult because of the presence of suboptimal exon and transmembrane domains at the C-terminal. In this study, we found that the <it>fgK </it>gene might not be expressed in a prokaryotic system in accordance with the bioinformatic predictions. Further, we successfully used bioinformatics tools to guide the prokaryotic expression of the <it>gK </it>gene by designing a novel truncated <it>gK </it>gene (<it>tgK</it>). These findings indicated that bioinformatics provides theoretical data for target gene expression and saves time for our research. The recombinant tgK protein (tgK) was expressed and purified by immobilized metal affinity chromatography (IMAC). Western blotting and indirect enzyme-linked immunosorbent assay (ELISA) showed that the tgK possessed antigenic characteristics similar to native DEV-gK.</p> <p>Conclusions</p> <p>In this work, the DEV-<it>tgK </it>was expressed successfully in prokaryotic system for the first time, which will provide usefull information for prokaryotic expression of alphaherpesvirus gK homologs, and the recombinant truncated gK possessed antigenic characteristics similar to native DEV gK. Because of the good reactionogenicity, specificity and sensitivity, the purified tgK could be useful for developing a sensitive serum diagnostic kit to monitor DEV outbreaks.</p

Expression and intracellular localization of duck enteritis virus pUL38 protein

Knowledge of the intracellular location of a protein can provide useful insights into its function. Bioinformatic studies have predicted that the DEV pUL38 mainly targets the cytoplasm and nucleus. In this study, we obtained anti-pUL38 polyclonal sera. These antibodies were functional in western blotting and immunofluorescence in DEV-infected duck embryo fibroblasts (DEFs). pUL38 was expressed as a 51-kDa protein from 8 h post-infection onward, initially showing a diffuse distribution throughout the cytoplasm, and later in the nucleus. Furthermore, pUL38 was found in purified virus. These results provide the first evidence of the kinetics of expression and intracellular localization of DEV pUL38

Expression and characterization of the UL31 protein from duck enteritis virus

<p>Abstract</p> <p>Background</p> <p>Previous studies indicate that the UL31 protein and its homology play similar roles in nuclear egress of all <it>herpesviruses</it>. However, there is no report on the UL31 gene product of DEV. In this study, we expressed and presented the basic properties of the DEV UL31 product.</p> <p>Results</p> <p>The entire ORF of the UL31 was cloned into pET 32a (+) prokaryotic expression vector. <it>Escherichia coli </it>BL21(DE3) competent cells were transformed with the construct followed by the induction of protein expression by the addition of IPTG. Band corresponding to the predicted sizes (55 kDa) was produced on the SDS-PAGE. Over expressed 6×His-UL31 fusion protein was purified by nickel affinity chromatography. The DEV UL31 gene product has been identified by using a rabbit polyclonal antiserum raised against the purified protein. A protein of approximate 35 kDa that reacted with the antiserum was detected in immunoblots of DEV-infected cellular lysates, suggesting that the 35 kDa protein was the primary translation product of the UL31 gene. RT-PCR analyses revealed that the UL31 gene was transcribed most abundantly during the late phase of replication. Subsequently, Immunofluorescence analysis revealed that the protein was widespread speckled structures in the nuclei of infected cells. Western blotting of purified virion preparations showed that UL31 was a component of intracellular virions but was absent from mature extracellular virions. Finally, an Immunofluorescence assay was established to study the distribution of the UL31 antigen in tissues of artificially DEV infected ducks. The results showed that the UL31 antigen was primarily located in the cells of digestive organs and immunological organs.</p> <p>Conclusion</p> <p>In this work, we present the basic properties of the DEV UL31 product. The results indicate that DEV UL31 shares many similarities with its HSV or PRV homolog UL31 and suggest that functional cross-complementation is possible between members of the <it>Alpha</it>herpesvirus subfamily. Furthermore, in vivo experiments with ducks infected with UL31-defective isolates of DEV will also be of importance in order to assess the possible role of the UL31 protein in viral pathogenesis. These properties of the UL31 protein provide a prerequisite for further functional analysis of this gene.</p

Cloning, expression and characterization of gE protein of Duck plague virus

<p>Abstract</p> <p>Background</p> <p>The gE protein of duck plague virus is the important membrane glycoprotein, its protein characterization has not been reported. In this study, we expressed and presented the characterization of the DPV gE product.</p> <p>Results</p> <p>According to the sequence of the gE gene, a pair of primers were designed, and the DNA product with 1490bp in size was amplified by using the polymerase chain reaction (PCR). The PCR product was cloned into pMD18-T vector, and subcloned into pET32a(+), generating the recombinant plasmid pET32a/DPV-gE. SDS-PAGE analysis showed that the fusion pET32a/DPV-gE protein was highly expressed after induction by 0.2 mM IPTG at 30°C for 4.5 h in Rosseta host cells. Over expressed 6×His-gE fusion protein was purified by nickel affinity chromatography, and used to immunize the rabbits for the preparation of polyclonal antibody. The result of the intracellular localization revealed that the gE protein was appeared to be in the cytoplasm region. The real time PCR, RT-PCR analysis and Western blotting revealed that the gE gene was produced most abundantly during the late phase of replication in DPV-infected cells.</p> <p>Conclusions</p> <p>In this work, the DPV gE protein was successfully expressed in a prokaryotic expression system, and we presented the basic properties of the DPV gE product for the first time. These properties of the gE protein provided a prerequisite for further functional analysis of this gene.</p

Immunofluorescence Analysis of Duck plague virus gE protein on DPV-infected ducks

<p>Abstract</p> <p>Background</p> <p>In previous studies, the expression and localization characteristics of duck plague virus (DPV) gE protein have been described in cultured cells, but the properties of DPV gE protein have not been reported in vivo. Immunofluorescence analysis had been used for the detection of virus antigen, but there was no report on the use of this technique for the detection of DPV gE. In this study, we investigated the distribution of DPV gE protein on DPV-infected ducks using polyclonal antibody raised against the recombinant His-gE fusion protein by indirect immunofluorescence assay (IFA).</p> <p>Results</p> <p>The recombinant gE protein was highly immunogenicity by ELISA, and the gE was used as an antigen for the preparation of polyclonal antibody, which could be used the first antibody for further experiment to study the distribution of DPV gE protein in DPV-infected tissues by indirect immunofluorescence assay. DPV gE protein were distributed in the immune organs (thymus, bursa of fabricius (BF), Harders glands, spleen), the digestive organs (liver, duodenum, jejunum, ileum), and the other parenchymatous organs (kidney, myocardium, cerebrum, and lung) of DPV-infected ducks, but the positive immunofluorescence signal was not seen in the muscle and pancreas. The lymphocytes, reticulum cells, macrophages, epithelial cells, and hepatocytes served as the principal site for the localization of DPV gE antigen. Moreover, the intensity of fluorescence increased sharply from 12 to 216 h post-infection (p.i.).</p> <p>Conclusions</p> <p>In this work, the immunogenicity of the recombinant gE protein was analyzed by ELISA, and we presented the distribution properties of DPV gE antigen in infected ducks for the first time, which may be useful for understanding the pathogenesis of DPV. These properties of the gE protein provided the prerequisite for further functional analysis.</p

Characterization of duck enteritis virus UL53 gene and glycoprotein K

<p>Abstract</p> <p>Background</p> <p>Most of the previous research work had focused on the epidemiology and prevention of duck enteritis virus (DEV). Whilst with the development of protocols in molecular biology, nowadays more and more information about the genes of DEV was reported. But little information about DEV UL53 gene and glycoprotein K(gK) was known except our reported data.</p> <p>Results</p> <p>In our paper, the fluorescent quantitative real-time PCR(FQ-RT-PCR) assay and nucleic acid inhibition test were used to study the transcription characteristic of the DEV UL53 gene. Except detecting the mRNA of DEV UL53 gene, the product gK encoded by UL53 gene was detected through the expression kinetics of UL53 gene by the purified rabbit anti-UL53 protein polyclonal antibodies. Western-blotting and indirect immunofluorescence assays were used to detect gK. From the results of these experiments, the UL53 gene and gK were respectively identified as a late gene and a really late protein. On the other hand, the indirect immunofluorescence assay provided another information that the intracellular localization of DEV gK was mainly distributed in cytoplasm.</p> <p>Conclusions</p> <p>By way of conclusions, we conceded that DEV UL53 gene is a really late gene, which is coincident with properties of UL53 homologs from other herpesvirus, such as ILTV(Infectious Laryngotracheitis virus) and HSV-1(Herpes simplex virus type 1). The properties of intracellular localization about gK protein provided a foundation for further functional analysis and further studies will be focused on constructing of the UL53 gene DEV mutant.</p