246 research outputs found
Solvable Model of Spiral Wave Chimeras
Spiral waves are ubiquitous in two-dimensional systems of chemical or
biological oscillators coupled locally by diffusion. At the center of such
spirals is a phase singularity, a topological defect where the oscillator
amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral
can occur, with a circular core consisting of desynchronized oscillators
running at full amplitude. Here we provide the first analytical description of
such a spiral wave chimera, and use perturbation theory to calculate its
rotation speed and the size of its incoherent core.Comment: 4 pages, 4 figures; added reference, figure, further numerical test
Polyimide based amorphous silicon solar modules
Requirements for space power are increasingly emphasizing lower costs and higher specific powers. This results from new fiscal constraints, higher power requirements for larger applications, and the evolution toward longer distance missions such as a Lunar or Mars base. The polyimide based a-Si modules described are being developed to meet these needs. The modules consist of tandem a-Si solar cell material deposited directly on a roll of polyimide. A laser scribing/printing process subdivides the deposition into discrete cell strips which are series connected to produce the required voltage without cutting the polymer backing. The result is a large, monolithic, blanket type module approximately 30 cm wide and variable in length depending on demand. Current production modules have a specific power slightly over 500 W/Kg with room for significant improvement. Costs for the full blanket modules range from 150/Watt depending on quantity and engineering requirements. Work to date focused on the modules themselves and adjusting them for the AMO spectrum. Work is needed yet to insure that the modules are suitable for the space environment
Deficiency of regulatory B cells increases allergic airway inflammation
Objective: To investigate the effect of the X-linked immunodeficiency (Xid) B cell defect on the response to the cockroach allergen in mice.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45272/1/11_2005_Article_1387.pd
A comparison of collision cross section values obtained via travelling wave ion mobility-mass spectrometry and ultra high performance liquid chromatography-ion mobility-mass spectrometry : application to the characterisation of metabolites in rat urine
A comprehensive Collision Cross Section (CCS) library was obtained via Travelling Wave Ion Guide mobility measurements through direct infusion (DI). The library consists of CCS and Mass Spectral (MS) data in negative and positive ElectroSpray Ionisation (ESI) mode for 463 and 479 endogenous metabolites, respectively. For both ionisation modes combined, TWCCSN2 data were obtained for 542 non-redundant metabolites. These data were acquired on two different ion mobility enabled orthogonal acceleration QToF MS systems in two different laboratories, with the majority of the resulting TWCCSN2 values (from detected compounds) found to be within 1% of one another. Validation of these results against two independent, external TWCCSN2 data sources and predicted TWCCSN2 values indicated to be within 1-2% of these other values. The same metabolites were then analysed using a rapid reversed-phase ultra (high) performance liquid chromatographic (U(H)PLC) separation combined with IM and MS (IM-MS) thus providing retention time (tr), m/z and TWCCSN2 values (with the latter compared with the DI-IM-MS data). Analytes for which TWCCSN2 values were obtained by U(H)PLC-IM-MS showed good agreement with the results obtained from DI-IM-MS. The repeatability of the TWCCSN2 values obtained for these metabolites on the different ion mobility QToF systems, using either DI or LC, encouraged the further evaluation of the U(H)PLC-IM-MS approach via the analysis of samples of rat urine, from control and methotrexate-treated animals, in order to assess the potential of the approach for metabolite identification and profiling in metabolic phenotyping studies. Based on the database derived from the standards 63 metabolites were identified in rat urine, using positive ESI, based on the combination of tr, TWCCSN2 and MS data.</p
Direct comparison of solution and solid phase synthesis of sequence-defined macromolecules
The synthesis of perfectly defined, monodisperse macromolecules is one of the challenges faced by polymer chemists today. Such precision synthesis requires a fundamentally different approach to conventional polymer synthesis, but in turn can unlock the door to many new applications. Therefore, we introduce here the combination of ultra-fast "click" reactions using 1,2,4-triazoline-3,5-diones (TAD) with the highly efficient and versatile Passerini three-component reaction. This new approach not only resulted in the synthesis of monodisperse, sequence-defined macromolecules of high purity and molecular weight (>7000 Da), but also offered new insights into the iterative synthesis of sequence-defined macromolecules in general, as we present a detailed comparative study of the same chemistry protocols carried out on solid phase as well as in solution
Chlorination of a Zeolitic-Imidazolate Framework Tunes Packing and van der Waals Interaction of Carbon Dioxide for Optimized Adsorptive Separation
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/jacs.0c08942.L.H.W. acknowledges the Fonds Wetenschappelijk Onderzoek
(FWO) - Vlaanderen for a senior postdoctoral research
fellowship and International Mobility fellowship under
contract numbers of 12M1418N and V402319N, respectively.
S.V.D.B., S.M.J.R., and J.W. acknowledge Fonds Wetenschappelijk
Onderzoek (FWO) - Vlaanderen for Grants 11U1914N,
12T3519N, and 1103618N as well as the Research Board of
Ghent University (BOF). J.A.R.N. acknowledges generous
funding from the Spanish Ministry of Economy (CTQ2014-
53486-R) and FEDER from the European Union. Funding was
also received from the European Union’s Horizon 2020
Research and Innovation Programme [ERC Consolidator
Grant Agreement 647755 - DYNPOR (2015−2020)]. J.A.M.
and C.E.A.K. gratefully acknowledge financial support from the
Flemish Government (Long-term structural funding Methusalem
and FWO support). Collaboration among universities was
supported by the Belgian Government (IAP-PAI network).Molecular separation of carbon dioxide (CO2) and methane (CH4) is of growing interest for biogas upgrading, carbon capture and utilization, methane synthesis and for purification of natural gas. Here, we report a new zeolitic-imidazolate framework (ZIF), coined COK-17, with exceptionally high affinity for the adsorption of CO2 by London dispersion forces, mediated by chlorine substituents of the imidazolate linkers. COK-17 is a new type of flexible zeolitic-imidazolate framework Zn(4,5-dichloroimidazolate)(2) with the SOD framework topology. Below 200 K it displays a metastable closed-pore phase next to its stable open-pore phase. At temperatures above 200 K, COK-17 always adopts its open-pore structure, providing unique adsorption sites for selective CO2 adsorption and packing through van der Waals interactions with the chlorine groups, lining the walls of the micropores. Localization of the adsorbed CO2 molecules by Rietveld refinement of X-ray diffraction data and periodic density functional theory calculations revealed the presence and nature of different adsorption sites. In agreement with experimental data, grand canonical Monte Carlo simulations of adsorption isotherms of CO2 and CH4 in COK-17 confirmed the role of the chlorine functions of the linkers and demonstrated the superiority of COK-17 compared to other adsorbents such as ZIF-8 and ZIF-71.FWO
12M1418N
V402319N
11U1914N
12T3519N
1103618NSpanish Ministry of Economy
CTQ201453486-RFEDER from the European UnionEuropean Union's Horizon 2020 Research and Innovation Programme [ERC]
647755 - DYNPORFlemish Government (Long-term structural funding Methusalem)FWOBelgian Government (IAP-PAI network
Ultrathin compound semiconductor on insulator layers for high performance nanoscale transistors
Over the past several years, the inherent scaling limitations of electron
devices have fueled the exploration of high carrier mobility semiconductors as
a Si replacement to further enhance the device performance. In particular,
compound semiconductors heterogeneously integrated on Si substrates have been
actively studied, combining the high mobility of III-V semiconductors and the
well-established, low cost processing of Si technology. This integration,
however, presents significant challenges. Conventionally, heteroepitaxial
growth of complex multilayers on Si has been explored. Besides complexity, high
defect densities and junction leakage currents present limitations in the
approach. Motivated by this challenge, here we utilize an epitaxial transfer
method for the integration of ultrathin layers of single-crystalline InAs on
Si/SiO2 substrates. As a parallel to silicon-on-insulator (SOI) technology14,we
use the abbreviation "XOI" to represent our compound semiconductor-on-insulator
platform. Through experiments and simulation, the electrical properties of InAs
XOI transistors are explored, elucidating the critical role of quantum
confinement in the transport properties of ultrathin XOI layers. Importantly, a
high quality InAs/dielectric interface is obtained by the use of a novel
thermally grown interfacial InAsOx layer (~1 nm thick). The fabricated FETs
exhibit an impressive peak transconductance of ~1.6 mS/{\mu}m at VDS=0.5V with
ON/OFF current ratio of greater than 10,000 and a subthreshold swing of 107-150
mV/decade for a channel length of ~0.5 {\mu}m
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Mutations in the Satellite Cell Gene MEGF10 Cause a Recessive Congenital Myopathy with Minicores
We ascertained a nuclear family in which three of four siblings were affected with an unclassified autosomal recessive myopathy characterized by severe weakness, respiratory impairment, scoliosis, joint contractures, and an unusual combination of dystrophic and myopathic features on muscle biopsy. Whole genome sequence from one affected subject was filtered using linkage data and variant databases. A single gene, MEGF10, contained nonsynonymous mutations that co-segregated with the phenotype. Affected subjects were compound heterozygous for missense mutations c.976T > C (p.C326R) and c.2320T > C (p.C774R). Screening the MEGF10 open reading frame in 190 patients with genetically unexplained myopathies revealed a heterozygous mutation, c.211C > T (p.R71W), in one additional subject with a similar clinical and histological presentation as the discovery family. All three mutations were absent from at least 645 genotyped unaffected control subjects. MEGF10 contains 17 atypical epidermal growth factor-like domains, each of which contains eight cysteine residues that likely form disulfide bonds. Both the p.C326R and p.C774R mutations alter one of these residues, which are completely conserved in vertebrates. Previous work showed that murine Megf10 is required for preserving the undifferentiated, proliferative potential of satellite cells, myogenic precursors that regenerate skeletal muscle in response to injury or disease. Here, knockdown of megf10 in zebrafish by four different morpholinos resulted in abnormal phenotypes including unhatched eggs, curved tails, impaired motility, and disorganized muscle tissue, corroborating the pathogenicity of the human mutations. Our data establish the importance of MEGF10 in human skeletal muscle and suggest satellite cell dysfunction as a novel myopathic mechanism
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