18 research outputs found

    Fe, N, S-doped porous carbon as oxygen reduction reaction catalyst in acidic medium with high activity and durability synthesized using CaCl2 as template

    Get PDF
    燃料电池是一种可将化学能通过电催化反应直接转化成电能的装置,具有能量密度高和清洁无污染等优点.燃料电池阴极氧还原反应(ORR)的动力学较迟缓,是; 电池能量效率损失的主要原因.目前ORR催化活性最高的是铂基催化剂,但由于贵金属铂价格昂贵,储量稀少,且对燃料小分子渗透的抗性较差,严重制约了燃料; 电池的大规模应用.因此,高性能、低成本的非贵金属催化剂成为燃料电池领域的研究热点.本文选用含氮量高达45%的三聚氰胺-甲醛树脂为碳源和氮源,Fe; (SCN)_3为铁源和硫源,以CaCl_2为模板,在高温和铁的催化作用下将树脂碳化,经酸洗和二次热处理工艺,制备出铁、氮、硫共掺杂的多孔碳(Fe; NS-PC).干燥后的CaCl_2颗粒可防止树脂在高温下交联形成块状碳颗粒,同时起到造孔模板的作用.CaCl_2颗粒在温和条件下即可除去,无需强; 腐蚀性条件,因此不会对催化活性中心造成破坏.在Fe/N/C催化剂中掺杂S可进一步提高催化活性,不添加碳载体可避免低活性的碳载体降低质量活性,多孔; 结构可促进传质,充分利用活性位点.我们优化了热处理温度,并对催化剂的结构、组分及催化性能等进行了表征分析.结果表明,热处理温度为900; °C时,可将树脂完全转化成多孔碳,并获得较高的杂原子掺杂量,可达到最优活性.CaCl_2为模板剂可避免使用强腐蚀性试剂去除模板,有利于保留活性位; ,并得到多孔结构.FeNS-PC-900的比表面积可达775; m~2/g.得益于原位掺杂的合成工艺,各掺杂元素在多孔碳表面均匀分布.在酸性介质中,FeNS-PC-900的半波电位可达到0.811; V,仅比商业Pt/C催化剂低78 mV;在0.8 V电位下的质量活性为10.2; A/g,表现出优异的催化活性.经过10000圈加速衰减测试后,其半波电位仅下降了20 mV,在0.75 V电位下持续放电10000; s后,其ORR电流仍保持初始电流的84.4%,具有比Pt/C更加优异的稳定性.以FeNS-PC-900为阴极催化剂的质子交换膜燃料电池的最大功率; 密度可达到0.49 W/cm~2,并在0.6 V电压下持续放电10; h后,其电流仍可保持初始电流的65%,表现出良好的应用潜力.FeNS-PC-900具有高掺杂含量、高比表面积和多孔结构,并且杂原子在催化剂表面均; 匀分散,在半电池和燃料电池测试中都表现出优异的催化活性和稳定性,表明其是一种非常有潜力应用于燃料电池的非贵金属氧还原催化剂.Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of Pt catalysts. In the present work, a high-performance ORR catalyst based on Fe, N, S-doped porous carbon (FeNS-PC) was synthesized using melamine formaldehyde resin as C and N precursors, Fe(SCN)(3) as Fe and S precursors, and CaCl2 as a template via a two-step heat treatment without a harsh template removal step. The results show that the catalyst treated at 900 degrees C (FeNS-PC-900) had a high surface area of 775 m(2)/g, a high mass activity of 10.2 A/g in an acidic medium, and excellent durability; the half-wave potential decreased by only 20 mV after 10000 potential cycles. The FeNS-PC-900 catalyst was used as the cathode in a proton exchange membrane fuel cell and delivered a peak power density of 0.49 W/cm(2). FeNS-PC-900 therefore has good potential for use in practical applications. (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 [2015CB932303]; National; Natural Science Foundation of China [21373175, 21621091

    STAT5 programs a distinct subset of GM-CSF-producing T helper cells that is essential for autoimmune neuroinflammation

    Get PDF
    T helper (TH)-cell subsets, such as TH1 and TH17, mediate inflammation in both peripheral tissues and central nervous system. Here we show that STAT5 is required for T helper-cell pathogenicity in autoimmune neuroinflammation but not in experimental colitis. Although STAT5 promotes regulatory T cell generation and immune suppression, loss of STAT5 in CD4+ T cells resulted in diminished development of experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Our results showed that loss of encephalitogenic activity of STAT5-deficient autoreactive CD4+ T cells was independent of IFN-γ or interleukin 17 (IL-17) production, but was due to the impaired expression of granulocyte-macrophage colony-stimulating factor (GM-CSF), a crucial mediator of T-cell pathogenicity. We further showed that IL-7-activated STAT5 promotes the generation of GM-CSF-producing CD4+ T cells, which were preferentially able to induce more severe EAE than TH17 or TH1 cells. Consistent with GM-CSF-producing cells being a distinct subset of TH cells, the differentiation program of these cells was distinct from that of TH17 or TH1 cells. We further found that IL-3 was secreted in a similar pattern as GM-CSF in this subset of TH cells. In conclusion, the IL-7-STAT5 axis promotes the generation of GM-CSF/IL-3-producing TH cells. These cells display a distinct transcriptional profile and may represent a novel subset of T helper cells which we designate as TH-GM

    Open Source ImmGen: network perspective on metabolic diversity among mononuclear phagocytes

    Get PDF
    We dissect metabolic variability of mononuclear phagocyte (MNP) subpopulations across different tissues through integrative analysis of three large scale datasets. Specifically, we introduce ImmGen MNP Open Source dataset that profiled 337 samples and extended previous ImmGen effort which included 202 samples of mononuclear phagocytes and their progenitors. Next, we analysed Tabula Muris Senis dataset to extract data for 51,364 myeloid cells from 18 tissues. Taken together, a compendium of data assembled in this work covers phagocytic populations found across 38 different tissues. To analyse common metabolic features, we developed novel network-based computational approach for unbiased identification of key metabolic subnetworks based on cellular transcriptional profiles in large-scale datasets. Using ImmGen MNP Open Source dataset as baseline, we define 9 metabolic subnetworks that encapsulate the metabolic differences within mononuclear phagocytes, and demonstrate that these features are robustly found across all three datasets, including lipid metabolism, cholesterol biosynthesis, glycolysis, and a set of fatty acid related metabolic pathways, as well as nucleotide and folate metabolism. We systematically define major features specific to macrophage and dendritic cell subpopulations. Among other things, we find that cholesterol synthesis appears particularly active within the migratory dendritic cells. We demonstrate that interference with this pathway through statins administration diminishes migratory capacity of the dendritic cells in vivo. This result demonstrates the power of our approach and highlights importance of metabolic diversity among mononuclear phagocytes

    Network analysis of large-scale ImmGen and Tabula Muris datasets highlights metabolic diversity of tissue mononuclear phagocytes

    Get PDF
    The diversity of mononuclear phagocyte (MNP) subpopulations across tissues is one of the key physiological characteristics of the immune system. Here, we focus on understanding the metabolic variability of MNPs through metabolic network analysis applied to three large-scale transcriptional datasets: we introduce (1) an ImmGen MNP open-source dataset of 337 samples across 26 tissues; (2) a myeloid subset of ImmGen Phase I dataset (202 MNP samples); and (3) a myeloid mouse single-cell RNA sequencing (scRNA-seq) dataset (51,364 cells) assembled based on Tabula Muris Senis. To analyze such large-scale datasets, we develop a network-based computational approach, genes and metabolites (GAM) clustering, for unbiased identification of the key metabolic subnetworks based on transcriptional profiles. We define 9 metabolic subnetworks that encapsulate the metabolic differences within MNP from 38 different tissues. Obtained modules reveal that cholesterol synthesis appears particularly active within the migratory dendritic cells, while glutathione synthesis is essential for cysteinyl leukotriene production by peritoneal and lung macrophages

    Tuina combined with moxibustion for 28 cases of lung-wei insecurity-type sweating syndrome in children

    Get PDF
    目的:探讨推拿配合艾灸治疗肺卫不固型小儿汗症的临床疗效。方法:采用小儿推拿结合艾灸治疗28例肺卫不固型小儿汗症患儿,推拿隔日一次,艾灸隔三日一次; ,治疗4周后观察临床疗效。结果:推拿配合艾灸治疗肺卫不固型小儿汗证的总有效率为92.85%。结论:推拿配合艾灸治疗肺卫不固型小儿汗证疗效肯定,值; 得临床上推广应用。Objective To explore the clinical efficacy of tuina combined with; moxibustion for treatment of lung-wei insecurity-type sweating syndrome; in children. Methods Infantile tuina combined with moxibustion was; conducted for 28 cases of lung-wei insecurity-type sweating syndrome in; children. Tuina was carried out for once every other day, and; moxibustion was conducted for once every other three days. Clinical; efficacy was observed after treatment for 4 weeks. Results The total eff; ective rate of tuina combined with moxibustion for treatment of lung-wei; insecurity-type sweating syndrome in children was 92.85%. Conclusion The; efficacy of tuina combined with moxibustion for treatment of lung-wei; insecurity-type sweating syndrome in children is definite, which is; worthy of being popularized clinically.Supported by Inheritance venation and academic idea study of Huxiang; five meridians combination acupuncturemoxibustion and tuina academic; schoo

    Estrogen Regulation of Proteinase Inhibitor 9 Gene Expression and Interleukin-1beta Production

    Get PDF
    148 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.The ability of several estrogens and antiestrogens to activate PI-9 gene expression was assessed by transient transfection. Of interest, the mixed agonist/antagonist tamoxifen (OHT) was an agonist on the transiently transfected reporter gene but behaved as an antagonist on the cellular gene. To begin to assess how OHT-ER interacts with the native PI-9 promoter we carded out chromatin immunoprecipitation (ChIP) assays. The ChIP assays demonstrated that moxestrol-ER complex bound to the PI-9 promoter, but that OHT-ER (and unliganded ER) did not bind. These data provide the first evidence that the agonist activity of OHT-ER stems from the inability of OHT to elicit conformational changes in chromatin which allow ER to bind to ERE's.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
    corecore