Spontaneous weaving: 3D porous PtCu networks with ultrathin jagged nanowires for highly efficient oxygen reduction reaction

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.apcatb.2018.04.035 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/We report a simple and efficient surfactant-free method to prepare 3D porous PtCu networks with ultrathin jagged nanowires and controllable composition. The morphological evolution and the influential effects of the important experimental parameters on the PtCu networks have been systematically studied. Relative to commercial Pt/C and Pt black catalysts, these porous PtCu networks exhibit much better activity and remarkably improved durability towards the oxygen reduction reaction (ORR). The excellent ORR performance could be attributed to their structural features, including the core-shell nanostructures with a Pt-skin, the 3D porous networks with high surface area, and the ultrathin (3.6 nm) jagged nanowires with plentiful edge/corner atoms. Notably, this method can be facilely extended to obtain PtCuAu trimetallic nanowire networks with high porosity, which exhibits its robustness for preparing novel 3D porous nanostructures with great potential in various catalytic applications.Natural Sciences and Engineering Research Council of Canada (NSERC) University of Waterloo, and the Waterloo Institute for Nanotechnology. NSERC, Catalysis Research for Polymer Electrolyte Fuel Cells (CaRPE FC) Network administered from Simon Fraser || Grant No. APCPJ 417858-1

MicroRNA-7 inhibits epithelial-to-mesenchymal transition and metastasis of breast cancer cells via targeting FAK expression

10.1371/journal.pone.0041523PLoS ONE78

Nitrogen-doped hollow porous carbon polyhedrons embedded with highly dispersed Pt nanoparticles as a highly efficient and stable hydrogen evolution electrocatalyst

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.nanoen.2017.07.032 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The hydrogen evolution reaction (HER) is a promising alternative method of producing clean and renewable hydrogen resources. Although Pt-based nanomaterials are the most efficient catalysts for HER, their poor stability and durability strongly impede their practical application. In this study, we report a new, efficient strategy to fabricate highly dispersed Pt nanoparticles within unique nitrogen-doped hollow porous carbon polyhedrons (Pt@NHPCP) derived from polymer coated metal-organic frameworks. Pt@NHPCP displays enhanced HER activity compared to commercial Pt/C. Most importantly, Pt@NHPCP exhibits excellent stability and durability, showing no nanostructure change and negligible activity decrease after 5000 potential cycles. The outstanding HER performance of Pt@NHPCP can be attributed to its unique structural features including highly dispersed Pt, nitrogen-doping, large surface area, hollow nanostructure and hierarchical pore system.Natural Sciences and Engineering Research Council of Canada (NSERC) University of Waterloo Waterloo Institute for Nanotechnology NSERC, Catalysis Research for Polymer Electrolyte Fuel Cells (CaRPE FC) Network administered from Simon Fraser || Grant No. APCPJ 417858-1

Enhanced B7-H4 expression in gliomas with low PD-L1 expression identifies super-cold tumors.

BACKGROUND: Characterizing expression profiles of different immune checkpoint molecules are promising for personalized checkpoint inhibitory immunotherapy. Gliomas have been shown as potential targets for immune checkpoint inhibitors recently. Our study was performed to determine coexpression levels of two major B7 immune regulatory molecules programmed death ligand 1 (PD-L1) and B7-H4, both of which have been demonstrated to inhibit antitumor host immunity in gliomas. METHODS: We assessed tumor tissues from stage II-IV primary gliomas (n=505) by immunohistochemistry (IHC) for protein levels of both PD-L1 and B7-H4. Gene coexpression analysis assessing clusters based on extent of PD-L1/B7-H4 classifier genes expression were investigated in two transcriptome datasets (The Cancer Genome Atlas and Chinese Glioma Genome Atlas). In addition, levels of immune cell infiltrates were estimated with IHC and RNA-seq data for assessing the tumor immune microenvironment of PD-L1/B7-H4 subgroups. RESULTS: High expression of PD-L1 and B7-H4 in gliomas was 23% and 20%, respectively, whereas coexpression of two proteins at high levels was limited to 2% of the cases. Comparable results were seen in RNA-seq datasets where PD-L1 mRNA expression levels negatively correlated with that of B7-H4. Gene coexpression modules clustered within each grade of gliomas demonstrated lack of double-high modules (cluster with high expression of both PD-L1 and B7-H4 classifier genes). B7-H4 mRNA expression levels showed negative correlation with extent of immune cell infiltration and High-B7-H4 module gliomas (high B7-H4 but low PD-L1 classifier genes expression) had less tumor-infiltrating lymphocytes (TILs) and tumor-associated macrophages (TAMs). IHC assessment also showed few TILs and TAMs in High-B7-H4 subgroup gliomas. CONCLUSIONS: The majority of gliomas express PD-L1 or B7-H4, however, coexpression of both at high levels is minimal. The high-B7-H4 patients could be considered as \u27super-cold\u27 gliomas with significantly deficient in TILs, suggesting that B7-H4 might inhibit T-cell trafficking into the central nervous system. This study demonstrated that PD-L1 and B7-H4 may serve as mutually compensatory immune checkpoint molecules in gliomas for immune targeted or active-specific immunotherapy. The distinct B7-H4 pathways modulating T-cell function and immune evasion in glioma patients deserved to be further explored in the future during immunotherapy

Metal-organic frameworks derived platinum-cobalt bimetallic nanoparticles in nitrogen-doped hollow porous carbon capsules as a highly active and durable catalyst for oxygen reduction reaction

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.apcatb.2017.11.077 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Pt-based nanomaterials are regarded as the most efficient electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). However, widespread adoption of PEMFCs requires solutions to major challenges encountered with ORR catalysts, namely high cost, sluggish kinetics, and low durability. Herein, a new efficient method utilizing Co-based metal-organic frameworks is developed to produce PtCo bimetallic nanoparticles embedded in unique nitrogen-doped hollow porous carbon capsules. The obtained catalyst demonstrates an outstanding ORR performance, with a mass activity that is 5.5 and 13.5 times greater than that of commercial Pt/C and Pt black, respectively. Most importantly, the product exhibits dramatically improved durability in terms of both electrochemically active surface area (ECAS) and mass activity compared to commercial Pt/C and Pt black catalysts. The remarkable ORR performance demonstrated here can be attributed to the structural features of the catalyst (its alloy structure, high dispersion and fine particle size) and the carbon support (its nitrogen dopant, large surface area and hollow porous structure).This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the University of Waterloo, and the Waterloo Institute for Nanotechnology. The authors greatly acknowledge the Catalysis Research for Polymer Electrolyte Fuel Cells (CaRPE FC) Network administered from Simon Fraser Grant No. APCPJ 417858-11 through NSERC. TEM imaging was performed at the Canadian Center for Electron Microscopy (CCEM) located at McMaster University. Part of EM work was performed at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy (DOE), Office of Basic Energy Science, under Contract No. DE-SC0012704

Embellished hollow spherical catalyst boosting activity and durability for oxygen reduction reaction

The final publication is available at Elsevier via https://doi.org/10.1016/j.nanoen.2018.07.031. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Transition metals hybridized to heteroatom doped carbon material can be regarded as the most promising non-noble candidate for boosting the sluggish kinetics of oxygen reduction reaction (ORR). However, it has always been a challenge to vastly boost the activity, and simultaneously retain a favorable structure from the supporting material. Herein, we prepared a high surface area hollow spherical carbon as a supporting material, and employed aminothiophenol (ATI) and poly-aminothiophenol (PATI) as heteroatom precursors to synthesize nitrogen and sulfur co-doped catalysts, i.e. HCS-A and HCS-PA, respectively. The two catalysts possessed chemically similar surface composition, and nearly identical chemical states for each element. However, only HCS-A was able to vastly inherit both morphological advantage and high surface area from the carbon support. In further half-cell electrochemical testing, HCS-A performed better ORR activities and higher selectivity toward 4 electron pathway than HCS-PA in both acidic and alkaline media. Moreover, HCS-A was proven to have excellent durability in half-cell testing, methanol tolerance as well as outstanding peak power density in both fuel cells and zinc-air batteries. This work not only indicates the promising performances of HCS-A, but more importantly offers a new viewpoint on the selection of heteroatom precursor to retain a favorable structure.University of WaterlooWaterloo Institute for NanotechnologyBallard Power SystemsCatalysis Research for Polymer Electrolyte Fuel Cells (CaRPE-FC), Simon Fraser UniversityNatural Sciences and Engineering Research Council || Automotive Partnership Canada Grant no. APCPJ 417858-1

Phospholamban as a crucial determinant of the inotropic response of human pluripotent stem cell-derived ventricular cardiomyocytes and tissue constructs

Human (h) pluripotent stem cells (PSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), serve as potentially unlimited ex vivo sources of cardiomyocytes (CMs) for disease modelling, drug discovery, cardiotoxicity screening and future clinical applications, including cardiac repair. Despite these advantages, a well-accepted obstacle to the widespread application of human PSC-derived CMs (hPSC-CMs) is their developmentally immature phenotype in terms of 〖Ca〗^(2+) handling and β-adrenergic signalling. To study these phenotypes, I used a cardiac ventricular specification protocol to differentiate multiple lines of hESCs and hiPSCs into CMs characterised by ventricular-like electrophysiological profiles. The hPSC-derived ventricular CMs (hPSC-VCMs) and engineered cardiac microtissues (hCMT) created from these cells displayed positive chronotropic (i.e. spontaneous rate) but null inotropic responses (i.e. contractile force) to β-adrenergic stimulation. These findings led me to hypothesize that phospholamban (PLB), an inhibitor of sarco/endoplasmic reticulum 〖Ca〗^(2+)-ATPase (SERCA) robustly present in adult CMs but poorly expressed in hPSC-VCMs, might account for the phenotypic differences observed between hPSC-VCMs and adult cardiomyocytes. Since PLB inhibition of SERCA is relieved by β-adrenergic stimulation in adult CMs, I investigated the functional consequences of altered PLB expression in hPSC-VCMs to obtain insights into developmental maturation. To induce the over-expression of wild-type PLB or a pseudophosphorylated (S16E) PLB, hPSC-VCMs were transduced by recombinant adenoviruses (Ad), Ad-PLB or Ad-S16E-PLB. As anticipated from the inhibitory effect of unphosphorylated PLB on SERCA, Ad-PLB transduction significantly (p<0.01) attenuated electrically evoked 〖Ca〗^(2+) transient amplitudes and prolonged 50% decay times. An important finding is that Ad-PLB-transduced hPSC-VCMs, rather than other groups, uniquely responded to isoproterenol, a β-adrenergic agonist. Consistent with relief from inhibition after phosphorylation of PLB, the Ad-S16E-PLB-transduced hPSC-VCMs exhibited an intermediate phenotype. Similar trend of functional changes were observed in Ad-PLB- and Ad-S16E-PLB-transduced hCMTs. Mechanistically, PLB overexpression altered neither the global transcriptomic profile nor the L-type calcium current (ICa,L). Taken together, these results demonstrate that forced expression of PLB directly restores the positive inotropic response of hPSC-VCMs to β-adrenergic stimulation. The results reported in this dissertation provide a better mechanistic understanding of the immaturity of hESC-VCMs and are expected to improve the construction of disease models and transplantable prototypes with adult-like physiological responses.published_or_final_versionPhysiologyDoctoralDoctor of Philosoph

基于PLC的碳纤维复合材料打磨喷涂生产线控制系统设计

According to the surface treatment process of carbon fiber composites,the overall plan of the production line about the carbon fiber composites surface polishing and spaying was designed,including the component and functional planning of control system,the design of program flow chart,the selection of PLC analysis,the design of I /O contact distribution,robot communication configuration,and the design of human-machine interface. The whole system design of the production line about the carbon fiber composites surface polishing and spaying were finally realized by the whole machine debugging

Shoot-Root Communication Plays a Key Role in Physiological Alterations of Rice (Oryza sativa) Under Iron Deficiency

Iron (Fe) is an essential mineral element required for plant growth, and when soil availability of Fe is low, plants show symptoms of severe deficiency. Under conditions of Fe deficiency, plants alter several processes to acquire Fe from soil. In this study, we used rice cultivars H 9405 with high Fe accumulation in seeds and Yang 6 with low Fe accumulation in seeds to study their physiological responses to different conditions of Fe availability. In both shoots and roots, the responses of ROS enzymes, leaf and root ultrastructure and photosynthetic system to iron deficiency in Yang 6 were much sensitive than those in H 9405. For the distribution of iron, the iron content was much higher in roots of Yang 6, in contrast to higher shoot content in H 9405. Differential responses were shown with the Fe content in roots and shoots, which were the opposite in the two varieties; thus, we proposed the existence of long-distance signals. Then split root and shoot removal experiments were used to demonstrate that a long-distance signal was involved in the iron-deficient rice plant, and the signal strength was highly correlated with the functional leaves