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Electron delocalization and charge mobility as a function of reduction in a metal–organic framework
Aubrey, Michael L.,Wiers, Brian M.,Andrews, Sean C.,Sakurai, Tsuneaki,Reyes-Lillo, Sebastian E.,Hamed, Samia M.,Yu, Chung-Jui,Darago, Lucy E.,Mason, Jarad A.,Baeg, Jin-Ook,Grandjean, Fernande,Long, Ga Nature Publishing Group UK 2018 Nature Materials Vol.17 No.7
<P>Conductive metal-organic frameworks are an emerging class of three-dimensional architectures with degrees of modularity, synthetic flexibility and structural predictability that are unprecedented in other porous materials. However, engendering long-range charge delocalization and establishing synthetic strategies that are broadly applicable to the diverse range of structures encountered for this class of materials remain challenging. Here, we report the synthesis of KxFe2(BDP)(3) (0 <= x <= 2; BDP2- =1,4-benzenedipyrazolate), which exhibits full charge delocalization within the parent framework and charge mobilities comparable to technologically relevant polymers and ceramics. Through a battery of spectroscopic methods, computational techniques and single-microcrystal field-effect transistor measurements, we demonstrate that fractional reduction of Fe-2(BDP)(3) results in a metal-organic framework that displays a nearly 10,000-fold enhancement in conductivity along a single crystallographic axis. The attainment of such properties in a KxFe2(BDP)(3) field-effect transistor represents the realization of a general synthetic strategy for the creation of new porous conductor-based devices.</P>
McDonald, ThomasM.,Lee, Woo Ram,Mason, Jarad A.,Wiers, Brian M.,Hong, Chang Seop,Long, Jeffrey R. American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.16
<P>Two new metal organic frameworks, M-2(dobpdc) (M = Zn (1), Mg (2); dobpdc(4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate), adopting an expanded MOF-74 structure type, were synthesized via solvothermal and microwave methods. Coordinatively unsaturated Mg2+ cations lining the 18.4-angstrom-diameter channels of 2 were functionalized with N,N'-dimethylethylenediamine (mmen) to afford Mg-2(dobpdc)-(mmen)(1.6)(H2O)(0.4) (mmen-Mg-2(dobpdc)). This compound displays an exceptional capacity for CO2 adsorption at low pressures, taking up 2.0 mmol/g (8.1 wt %) at 0.39 mbar and 25 degrees C, conditions relevant to removal of CO2 from air, and 3.14 mmol/g (12.1 wt %) at 0.15 bar and 40 degrees C, conditions relevant to CO2 capture from flue gas. Dynamic gas adsorption/desorption cycling experiments demonstrate that mmen-Mg-2(dobpdc) can be regenerated upon repeated exposures to simulated air and flue gas mixtures, with cycling capacities of 1.05 mmol/g (4.4 wt %) after 1 h of exposure to flowing 390 ppm CO2 in simulated air at 25(degrees)C and 2.52 mmol/g (9.9 wt %) after 15 min of exposure to flowing 15% CO2 in N-2 at 40 degrees C. The purity of the CO2 removed from dry air and flue gas in these processes was estimated to be 96% and 98%, respectively. As a flue gas adsorbent, the regeneration energy was estimated through differential scanning calorimetry experiments to be 2.34 MJ/kg CO2 adsorbed. Overall, the performance characteristics of mmen-Mg-2(dobpdc) indicate it to be an exceptional new adsorbent for CO2 capture, comparing favorably with both amine-grafted silicas and aqueous amine solutions.</P>
Van Oss, S. Branden,Shirra, Margaret K.,Bataille, Alain R.,Wier, Adam D.,Yen, Kuangyu,Vinayachandran, Vinesh,Byeon, In-Ja L.,Cucinotta, Christine E.,Hé,roux, Annie,Jeon, Jongcheol,Kim, Jaehoon,V Elsevier 2016 Molecular cell Vol.64 No.4
<P><B>Summary</B></P> <P>The five-subunit yeast Paf1 complex (Paf1C) regulates all stages of transcription and is critical for the monoubiquitylation of histone H2B (H2Bub), a modification that broadly influences chromatin structure and eukaryotic transcription. Here, we show that the histone modification domain (HMD) of Paf1C subunit Rtf1 directly interacts with the ubiquitin conjugase Rad6 and stimulates H2Bub independently of transcription. We present the crystal structure of the Rtf1 HMD and use site-specific, in vivo crosslinking to identify a conserved Rad6 interaction surface. Utilizing ChIP-exo analysis, we define the localization patterns of the H2Bub machinery at high resolution and demonstrate the importance of Paf1C in targeting the Rtf1 HMD, and thereby H2Bub, to its appropriate genomic locations. Finally, we observe HMD-dependent stimulation of H2Bub in a transcription-free, reconstituted in vitro system. Taken together, our results argue for an active role for Paf1C in promoting H2Bub and ensuring its proper localization in vivo.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Histone modification domain (HMD) of Rtf1 directly contacts Rad6 in vivo </LI> <LI> HMD structure and in vivo crosslinking identify a conserved Rad6 interaction surface </LI> <LI> Paf1C regulates global H2B ubiquitylation (ub) patterns by linking HMD to Pol II </LI> <LI> HMD stimulates Bre1-dependent H2Bub in a transcription-free, reconstituted assay </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>
Interobserver agreement for detecting Hill-Sachs lesions on magnetic resonance imaging
Hassanin Alkaduhimi,Aimane Saarig,Ihsan Amajjar,Just A. van der Linde,Marieke F. van Wier,Nienke W. Willigenburg,Michel P.J. van den Bekerom 대한견주관절의학회 2021 대한견주관절의학회지 Vol.24 No.2
Background: Our aim is to determine the interobserver reliability for surgeons to detect Hill-Sachs lesions on magnetic resonance imaging (MRI), the certainty of judgement, and the effects of surgeon characteristics on agreement. Methods: Twenty-nine patients with Hill-Sachs lesions or other lesions with a similar appearance on MRIs were presented to 20 surgeons without any patient characteristics. The surgeons answered questions on the presence of Hill-Sachs lesions and the certainty of diagnosis. Interobserver agreement was assessed using the Fleiss’ kappa (κ) and percentage of agreement. Agreement between surgeons was compared using a technique similar to the pairwise t-test for means, based on large-sample linear approximation of Fleiss’ kappa, with Bonferroni correction. Results: The agreement between surgeons in detecting Hill-Sachs lesions on MRI was fair (69% agreement; κ, 0.304; p<0.001). In 84% of the cases, surgeons were certain or highly certain about the presence of a Hill-Sachs lesion. Conclusions: Although surgeons reported high levels of certainty for their ability to detect Hill-Sachs lesions, there was only a fair amount of agreement between surgeons in detecting Hill-Sachs lesions on MRI. This indicates that clear criteria for defining Hill-Sachs lesions are lacking, which hampers accurate diagnosis and can compromise treatment.
Yeon, Je Seon,Lee, Woo Ram,Kim, Nam Woo,Jo, Hyuna,Lee, Hanyeong,Song, Jeong Hwa,Lim, Kwang Soo,Kang, Dong Won,Seo, Jeong Gil,Moon, Dohyun,Wiers, Brian,Hong, Chang Seop The Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.37
<▼1><P>The functionalized MOFs exhibit exceptional CO2/N2 adsorption capacity and selectivity, associated with the basicity of the introduced amine groups.</P></▼1><▼2><P>A porous Mg2(dondc) framework (H4dondc = 1,5-dioxido-2,6-naphthalenedicarboxylic acid) with open metal sites was prepared and functionalized with primary or secondary diamines (en = ethylenediamine, mmen = <I>N</I>,<I>N</I>′-dimethylethylenediamine, or ppz = piperazine). The CO2 adsorption was substantial under post-combustion flue gas conditions as compared to other reported metal–organic frameworks. Interestingly, the IR spectroscopic measurements demonstrated that the CO2 adsorption mechanism is based on the combination of physisorption and chemisorption. The CO2 adsorption capacity of 1-mmen was greater than that of 1-en and 1-ppz, which can likely be attributed to the basicity of the free amine groups tethered to the open coordination sites. Ultrahigh selectivity and superior dynamic separation of CO2 over N2 were evident in 1-ppz. Such exceptional CO2 uptake and CO2/N2 selectivity of diamine-functionalized materials hold potential promise for post-combustion CO2 capture applications.</P></▼2>