Wide-bandgap power semiconductors for electric vehicle systems: Challenges and trends

In recent years, researchers have been attracted to the application of wide-bandgap (WBG) power semiconductor devices such as silicon carbide (SiC) and gallium nitride (GaN) in electric vehicle (EV) applications. Their advantages over Si power semiconductors are lower power losses, higher switching frequencies, and higher junction temperatures. Thus, using WBG power semiconductor devices for EV power electronic systems improves EV efficiency, reliability, and mileage; however, these adoptions are still under challenges in terms of packaging and power converters design. In this article, future trends and prospects of using WBG power semiconductor devices in EV systems are first presented. Then, the recent progress of different commercial WBG power semiconductor devices is reviewed and different solutions are reported to overcome R&D obstacles

A Dashboard to Support Decision-Making Processes in Learning Ecosystems

There are software solutions to solve most of the problems related to information management in any company or institutions, but still, there is a problem for transforming information into knowledge. Technological ecosystems emerge as a solution to combine existing tools and human resources to solve different problems of knowledge management. In particular, when the ecosystem is focused on learning processes associated with knowledge are named learning ecosystems. The learning ecosystem metamodel defined in previous works solves several problems related to the definition and implementation of these solutions. However, there are still challenges associated with improving the analysis and visualization of information as a way to discover knowledge and support decision making processes. On the other hand, there is a metamodel proposal to define customized dashboards for supporting decision-making processes. This proposal aims to integrate both metamodels as a way to improve the definition of learning ecosystems

Background risk of breast cancer and the association between physical activity and mammographic density

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/ by/4.0

IL-7 Promotes CD95-Induced Apoptosis in B Cells via the IFN-γ/STAT1 Pathway

Interleukin-7 (IL-7) concentrations are increased in the blood of CD4+ T cell depleted individuals, including HIV-1 infected patients. High IL-7 levels might stimulate T cell activation and, as we have shown earlier, IL-7 can prime resting T cell to CD95 induced apoptosis as well. HIV-1 infection leads to B cell abnormalities including increased apoptosis via the CD95 (Fas) death receptor pathway and loss of memory B cells. Peripheral B cells are not sensitive for IL-7, due to the lack of IL-7Ra expression on their surface; however, here we demonstrate that high IL-7 concentration can prime resting B cells to CD95-mediated apoptosis via an indirect mechanism. T cells cultured with IL-7 induced high CD95 expression on resting B cells together with an increased sensitivity to CD95 mediated apoptosis. As the mediator molecule responsible for B cell priming to CD95 mediated apoptosis we identified the cytokine IFN-γ that T cells secreted in high amounts in response to IL-7. These results suggest that the lymphopenia induced cytokine IL-7 can contribute to the increased B cell apoptosis observed in HIV-1 infected individuals

Harmonic Sums and Mellin Transforms up to two-loop Order

A systematic study is performed on the finite harmonic sums up to level four. These sums form the general basis for the Mellin transforms of all individual functions $f_i(x)$ of the momentum fraction $x$ emerging in the quantities of massless QED and QCD up to two--loop order, as the unpolarized and polarized splitting functions, coefficient functions, and hard scattering cross sections for space and time-like momentum transfer. The finite harmonic sums are calculated explicitly in the linear representation. Algebraic relations connecting these sums are derived to obtain representations based on a reduced set of basic functions. The Mellin transforms of all the corresponding Nielsen functions are calculated.Comment: 44 pages Latex, contract number adde

The androgen receptor gene CAG repeat in relation to 4-year changes in androgen-sensitive endpoints in community-dwelling older European men

Context: The Androgen Receptor (AR) gene exon 1 CAG repeat length has been proposed to be a determinant of between-individual variations in androgen action in target tissues, which might regulate phenotypic differences of human ageing. However, findings on its phenotypic effects are inconclusive.Objective: To assess whether the AR CAG repeat length is associated with longitudinal changes in endpoints which are influenced by testosterone (T) levels in middle-aged and elderly European men.Design: Multinational European observational prospective cohort studyParticipants: 1887 men (mean±sd age: 63±11 years; median follow-up: 4.3 years) from centres of 8 European countries comprised the analysis sample after exclusion of those with diagnosed diseases of the hypothalamic-pituitary-testicular (HPT) axis.Main outcome measures: Longitudinal associations between the AR CAG repeat and changes in androgen-sensitive endpoints (ASEs) and medical conditions were assessed using regression analysis adjusting for age and centre. The AR CAG repeat length was treated both as a continuous and categorical (6-20; 21-23; 24-39 repeats) predictor. Additional analysis investigated whether results were independent of baseline T or oestradiol (E2) levels.Results: The AR CAG repeat, when used as a continuous or categorical predictor, was not associated with longitudinal changes in ASEs or medical conditions after adjustments. These results were independent of T and E2 levels.Conclusion: Within a 4-year timeframe, variations in the AR CAG repeat do not contribute to the rate of phenotypic ageing, over and above, that, which might be associated with the age-related decline in T levels

Metal organic framework nanosheets in polymer composite materials for gas separation

[EN] Composites incorporating two-dimensional nanostructures within polymeric matrices have potential as functional components for several technologies, including gas separation. Prospectively, employing metal-organic frameworks (MOFs) as versatile nanofillers would notably broaden the scope of functionalities. However, synthesizing MOFs in the form of freestanding nanosheets has proved challenging. We present a bottom-up synthesis strategy for dispersible copper 1,4-benzenedicarboxylate MOF lamellae of micrometre lateral dimensions and nanometre thickness. Incorporating MOF nanosheets into polymer matrices endows the resultant composites with outstanding CO2 separation performance from CO2/CH4 gas mixtures, together with an unusual and highly desired increase in the separation selectivity with pressure. As revealed by tomographic focused ion beam scanning electron microscopy, the unique separation behaviour stems from a superior occupation of the membrane cross-section by the MOF nanosheets as compared with isotropic crystals, which improves the efficiency of molecular discrimination and eliminates unselective permeation pathways. This approach opens the door to ultrathin MOF-polymer composites for various applications.The research leading to these results has received funding (J.G., B.S.) from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 335746, CrystEng-MOF-MMM. T.R. is grateful to TUDelft for funding. G.P. acknowledges the A. von Humboldt Foundation for a research grant. A.C., I.L. and F.X.L.i.X. thank Consolider-Ingenio 2010 (project MULTICAT) and the ‘Severo Ochoa’ programme for support. I.L. also thanks CSIC for a JAE doctoral grant.Ródenas Torralba, T.; Luz Mínguez, I.; Prieto González, G.; Seoane, B.; Miro, H.; Corma Canós, A.; Kapteijn, F.... (2015). Metal organic framework nanosheets in polymer composite materials for gas separation. Nature Materials. 14(1):48-55. https://doi.org/10.1038/nmat4113S4855141Stankovich, S. et al. Graphene-based composite materials. Nature 442, 282–286 (2006).Wang, Q. H., Kalantar-Zadeh, K., Kis, A., Coleman, J. N. & Strano, M. S. Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nature Nanotech. 7, 699–712 (2012).Choi, S. et al. Layered silicates by swelling of AMH-3 and nanocomposite membranes. Angew. Chem. Int. Ed. 47, 552–555 (2008).Varoon, K. et al. Dispersible exfoliated zeolite nanosheets and their application as a selective membrane. Science 334, 72–75 (2011).Corma, A., Fornes, V., Pergher, S. B., Maesen, Th. L. M. & Buglass, J. G. Delaminated zeolite precursors as selective acidic catalysts. Nature 396, 353–356 (1998).Hernandez, Y. et al. High-yield production of graphene by liquid-phase exfoliation of graphite. Nature Nanotech. 3, 563–568 (2008).Li, P-Z., Maeda, Y. & Xu, Q. Top-down fabrication of crystalline metal-organic framework nanosheets. Chem. Commun. 47, 8436–8438 (2011).Choi, M. et al. Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts. Nature 461, 246–249 (2009).Hu, G., Wang, N., O’Hare, D. & Davis, J. One-step synthesis and AFM imaging of hydrophobic LDH monolayers. Chem. Commun. 287–289 (2006).Yamamoto, K., Sakata, Y., Nohara, Y., Takahashi, Y. & Tatsumi, T. Organic-inorganic hybrid zeolites containing organic frameworks. Science 300, 470–472 (2003).Yaghi, O. M. et al. Reticular synthesis and the design of new materials. Nature 423, 705–714 (2003).Férey, G. Hybrid porous solids: Past, present, future. Chem. Soc. Rev. 37, 191–214 (2008).Gücüyener, C., Bergh, J., Gascon, J. & Kapteijn, F. Ethane/ethene separation turned on its head: Selective ethane adsorption on the metal-organic framework ZIF-7 through a gate-opening mechanism. J. Am. Chem. Soc. 132, 17704–17706 (2010).Deng, H. et al. Multiple functional groups of varying ratios in metal-organic frameworks. Science 12, 846–850 (2010).Khaletskaya, K. et al. Integration of porous coordination polymers and gold nanorods into core-shell mesoscopic composites toward light-induced molecular release. J. Am. Chem. Soc. 135, 10998–11005 (2013).Corma, A., Garcia, H. & Llabrés i Xamena, F. X. Engineering metal organic frameworks for heterogeneous catalysis. Chem. Rev. 110, 4606–4655 (2010).Mueller, U. et al. Metal-organic frameworks-prospective industrial applications. J. Mater. Chem. 16, 626–636 (2006).Gascon, J. & Kapteijn, F. Metal-organic framework membranes-high potential, bright future? Angew. Chem. Int. Ed. 49, 1530–1532 (2010).Li, Y. S. et al. Controllable synthesis of metal-organic frameworks: From MOF nanorods to oriented MOF membranes. Adv. Mater. 22, 3322–3326 (2010).Gascon, J. et al. Practical approach to zeolitic membranes and coatings: State of the art, opportunities, barriers, and future perspectives. Chem. Mater. 24, 2829–2844 (2012).Bae, T-H. et al. A high-performance gas-separation membrane containing submicrometer-sized metal-organic framework crystals. Angew. Chem. Int. Ed. 49, 9863–9866 (2010).Zornoza, B. et al. Functionalized flexible MOFs as fillers in mixed matrix membranes for highly selective separation of CO2 from CH4 at elevated pressures. Chem. Commun. 47, 9522–9524 (2011).Zornoza, B., Tellez, C., Coronas, J., Gascon, J. & Kapteijn, F. Metal organic frameworks based mixed matrix membranes: An increasingly important field of research with a large application potential. Microp. Mesop. Mater. 166, 67–78 (2013).Zhang, C., Dai, Y., Johnson, J. R., Karvan, O. & Koros, W. High performance ZIF-8/6FDA-DAM mixed matrix membrane for propylene/propane separations. J. Mem. Sci. 389, 34–42 (2012).Li, T., Pan, Y., Peinemann, K-V. & Lai, Z. Carbon dioxide selective mixed matrix composite membrane containing ZIF-7 nano-fillers. J. Mem. Sci. 425–426, 235–242 (2013).Makiura, R. et al. Surface nano-architecture of a metal-organic framework. Nature Mater. 9, 565–571 (2010).Mori, W. et al. Synthesis of new adsorbent copper(II) terephthalate. Chem. Lett. 26, 1219–1220 (1997).Xin, Z., Bai, J., Shen, Y. & Pan, Y. Hierarchically micro- and mesoporous coordination polymer nanostructures with high adsorption performance. Cryst. Growth Des. 10, 2451–2454 (2010).Adams, R., Carson, C., Ward, J., Tannenbaum, R. & Koros, W. Metal organic framework mixed matrix membranes for gas separations. Micropor. Mesopor. Mater. 131, 13–20 (2010).Carson, C. G. et al. Synthesis and structure characterization of copper terephthalate metal-organic framework. Eur. J. Inorg. Chem. 2009, 2338–2343 (2009).Ameloot, R. et al. Interfacial synthesis of hollow metal-organic framework capsules demonstrating selective permeability. Nature Chem. 3, 382–387 (2011).Chen, Z. et al. Microporous metal-organic framework with immobilized -OH functional groups within the pore surfaces for selective gas sorption. Eur. J. Inorg. Chem. 2010, 3745–3749 (2010).Karra, J. R. & Walton, K. S. Molecular simulations and experimental studies of CO2, CO, and N2 adsorption in metal-organic frameworks. J. Phys. Chem. C 114, 15735–15740 (2010).Liu, J., Thallapally, P. K., McGrail, B. P., Brown, D. R. & Liu, J. Progress in adsorption-based CO2 capture by metal-organic frameworks. Chem. Soc. Rev. 41, 2308–2322 (2012).Seki, K., Takamizawa, S. & Mori, W. Characterization of microporous copper(II) dicarboxylates (fumarate, terephthalate, and trans-1,4-cyclohexanedicarboxylate) by gas adsorption. Chem. Lett. 30, 122–123 (2001).Carson, C. G. et al. Structure solution from powder diffraction of copper 1,4-benzenedicarboxylate. Eur. J. Inorg. Chem. 2014, 2140–2145 (2014).Corma, A., Diaz, U., Domine, M. E. & Fornes, V. AlITQ-6 and TiITQ-6: Synthesis, characterization, and catalytic activity. Angew. Chem. Int. Ed. 39, 1499–1501 (2000).Corma, A., Fornes, V. & Diaz, U. ITQ-18 a new delaminated stable zeolite. Chem. Commun. 2642–2643 (2001).Rouquerol, F., Rouquerol, J. & Sing, K. Adsorption by Powders and Porous Solids (Academic, 1999).Dubinin, M. M. The potential theory of adsorption of gases and vapors for adsorbents with energetically nonuniform surfaces. Chem. Rev. 60, 235–241 (1960).Uchic, M. D., Holzer, L., Inkson, B. J., Principe, E. L. & Munroe, P. Three-dimensional microstructural characterization using focused ion beam tomography. Mater. Res. Soc. Bull. 32, 408–416 (2007).Rodenas, T. et al. Visualizing MOF mixed matrix membranes at the nanoscale: Towards structure-performance relationships in CO2/CH4 separation over NH2-MIL-53(Al)@PI. Adv. Funct. Mater. 24, 249–256 (2013).Wang, X. et al. Unusual rheological behaviour of liquid polybutadiene rubber/clay nanocomposite gels: The role of polymer-clay interaction, clay exfoliation, and clay orientation and disorientation. Macromology 39, 6653–6660 (2006).Yang, Y. et al. Progress in carbon dioxide separation and capture: A review. J. Environ. Sci. 20, 14–27 (2008).Yeo, Z. Y., Chew, T. L., Zhu, P. W., Mohamed, A. R. & Chai, S-P. Conventional processes and membrane technology for carbon dioxide removal from natural gas: A review. J. Nature Gas Chem. 21, 282–298 (2012).McKeown, N. B. & Budd, P. M. Polymers of intrinsic microporosity (PIMs): Organic materials for membrane separations, heterogeneous catalysis and hydrogen storage. Chem. Soc. Rev. 35, 675–683 (2006).Vinh-Thang, H. & Kaliaguine, S. Predictive models for mixed-matrix membrane performance: A review. Chem. Rev. 113, 4980–5028 (2013)

Reduced microvascular density in omental biopsies of children with chronic kidney disease

Endothelial dysfunction is an early manifestation of cardiovascular disease (CVD) and consistently observed in patients with chronic kidney disease (CKD). We hypothesized that CKD is associated with systemic damage to the microcirculation, preceding macrovascular pathology. To assess the degree of "uremic microangiopathy", we have measured microvascular density in biopsies of the omentum of children with CKD.Omental tissue was collected from 32 healthy children (0-18 years) undergoing elective abdominal surgery and from 23 age-matched cases with stage 5 CKD at the time of catheter insertion for initiation of peritoneal dialysis. Biopsies were analyzed by independent observers using either a manual or an automated imaging system for the assessment of microvascular density. Quantitative immunohistochemistry was performed for markers of autophagy and apoptosis, and for the abundance of the angiogenesis-regulating proteins VEGF-A, VEGF-R2, Angpt1 and Angpt2.Microvascular density was significantly reduced in uremic children compared to healthy controls, both by manual imaging with a digital microscope (median surface area 0.61% vs. 0.95%, p<0.0021 and by automated quantification (total microvascular surface area 0.89% vs. 1.17% p = 0.01). Density measured by manual imaging was significantly associated with age, height, weight and body surface area in CKD patients and healthy controls. In multivariate analysis, age and serum creatinine level were the only independent, significant predictors of microvascular density (r2 = 0.73). There was no immunohistochemical evidence for apoptosis or autophagy. Quantitative staining showed similar expression levels of the angiogenesis regulators VEGF-A, VEGF-receptor 2 and Angpt1 (p = 0.11), but Angpt2 was significantly lower in CKD children (p = 0.01).Microvascular density is profoundly reduced in omental biopsies of children with stage 5 CKD and associated with diminished Angpt2 signaling. Microvascular rarefaction could be an early systemic manifestation of CKD-induced cardiovascular disease