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https://www.readbyqxmd.com/read/28640849/motility-in-blastogregarines-apicomplexa-native-and-drug-induced-organisation-of-siedleckia-nematoides-cytoskeletal-elements
#1
Andrea Valigurová, Naděžda Vaškovicová, Andrei Diakin, Gita G Paskerova, Timur G Simdyanov, Magdaléna Kováčiková
Recent studies on motility of Apicomplexa concur with the so-called glideosome concept applied for apicomplexan zoites, describing a unique mechanism of substrate-dependent gliding motility facilitated by a conserved form of actomyosin motor and subpellicular microtubules. In contrast, the gregarines and blastogregarines exhibit different modes and mechanisms of motility, correlating with diverse modifications of their cortex. This study focuses on the motility and cytoskeleton of the blastogregarine Siedleckia nematoides Caullery et Mesnil, 1898 parasitising the polychaete Scoloplos cf...
2017: PloS One
https://www.readbyqxmd.com/read/28640630/suzuki-miyaura-cross-coupling-of-n-acylpyrroles-and-pyrazoles-planar-electronically-activated-amides-in-catalytic-n-c-cleavage
#2
Guangrong Meng, Roman Szostak, Michal Szostak
The formation of C-C bonds from amides by catalytic activation of the amide bond has been thus far possible by steric distortion. Herein, we report the first example of a general Pd-catalyzed Suzuki-Miyaura cross-coupling of planar amides enabled by the combination of (i) electronic-activation of the amide nitrogen in N-acylpyrroles and pyrazoles and (ii) the use of a versatile Pd-NHC catalysis platform. The origin and selectivity of forming acylmetals, including the role of twist, are discussed.
June 22, 2017: Organic Letters
https://www.readbyqxmd.com/read/28640616/the-twist-of-a-silicon-silicon-double-bond-selective-anti-addition-of-hydrogen-to-an-iminodisilene
#3
Daniel Wendel, Tibor Szilvási, Christian Jandl, Shigeyoshi Inoue, Bernhard Rieger
Hydrogenation of alkenes with C=C bonds is a ubiquitous reaction in organic chemistry. However, this transformation remains unknown for heavier counterparts, disilenes with Si=Si bonds. Here we report the isolation of (Z)-diiminodisilyldisilene 2 featuring a highly trans-bent and twisted structure and the longest silicon-silicon double bond reported to date. In silico studies suggested that the Si=Si bond in 2 is described as very weak double donor-acceptor bond. We utilized the remarkable electronic and structural features of this product to achieve the first demonstration of hydrogen activation by a multiply bonded silicon compound under ambient conditions...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28637227/echocardiographic-reference-ranges-for-normal-left-ventricular-2d-strain-results-from-the-eacvi-norre-study
#4
Tadafumi Sugimoto, Raluca Dulgheru, Anne Bernard, Federica Ilardi, Laura Contu, Karima Addetia, Luis Caballero, Natela Akhaladze, George D Athanassopoulos, Daniele Barone, Monica Baroni, Nuno Cardim, Andreas Hagendorff, Krasimira Hristova, Teresa Lopez, Gonzalo de la Morena, Bogdan A Popescu, Marie Moonen, Martin Penicka, Tolga Ozyigit, Jose David Rodrigo Carbonero, Nico van de Veire, Ralph Stephan von Bardeleben, Dragos Vinereanu, Jose Luis Zamorano, Yun Yun Go, Monica Rosca, Andrea Calin, Julien Magne, Bernard Cosyns, Stella Marchetta, Erwan Donal, Gilbert Habib, Maurizio Galderisi, Luigi P Badano, Roberto M Lang, Patrizio Lancellotti
Aims: To obtain the normal ranges for 2D echocardiographic (2DE) measurements of left ventricular (LV) strain from a large group of healthy volunteers accounting for age and gender. Methods and results: A total of 549 (mean age: 45.6 ± 13.3 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. 2DE data sets have been analysed with a vendor-independent software package allowing homogeneous measurements irrespective of the echocardiographic equipment used to acquire the data sets...
June 16, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28636918/actin-filament-strain-promotes-severing-and-cofilin-dissociation
#5
Anthony C Schramm, Glen M Hocky, Gregory A Voth, Laurent Blanchoin, Jean-Louis Martiel, Enrique M De La Cruz
Computational and structural studies have been indispensable in investigating the molecular origins of actin filament mechanical properties and modulation by the regulatory severing protein cofilin. All-atom molecular dynamics simulations of cofilactin filament structures determined by electron cryomicroscopy reveal how cofilin enhances the bending and twisting compliance of actin filaments. Continuum mechanics models suggest that buckled cofilactin filaments localize elastic energy at boundaries between bare and cofilin-decorated segments because of their nonuniform elasticity, thereby accelerating filament severing...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636915/probing-the-structural-dynamics-of-the-nmda-receptor-activation-by-coarse-grained-modeling
#6
Wenjun Zheng, Han Wen, Gary J Iacobucci, Gabriela K Popescu
N-Methyl-D-aspartate (NMDA) receptors are glutamate-gated excitatory channels that play essential roles in brain functions. High-resolution structures have been solved for an allosterically inhibited and agonist-bound form of a functional NMDA receptor; however, other key functional states (particularly the active open-channel state) were only resolved at moderate resolutions by cryo-electron microscopy (cryo-EM). To decrypt the mechanism of the NMDA receptor activation, structural modeling is essential to provide presently missing information about structural dynamics...
June 20, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28636376/on-the-mechanism-of-the-iodide-triiodide-exchange-reaction-in-a-solid-state-ionic-liquid
#7
Joás Grossi, Jorge J Kohanoff, Niall J English, Eduardo M Bringa, Mario G Del Pópolo
Efficient charge transport has been observed in iodide-based room-temperature ionic liquids when doped with iodine. To investigate preferred pathways for the iodide (I(-))-to-triiodide (I3(-)) exchange reaction and to clarify the origin of this high ionic conductivity, we have conducted electronic structure calculations in the crystal state of 1-butyl-3-methylimidazolium iodide ([BMIM][I]). Energy barriers for the different stages of the iodine-swapping process, including the reorientation of the I(-)···I3(-) moiety, were determined from minimum energy paths as a function of a reaction coordinate...
June 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28634300/understanding-the-mechanical-response-of-double-stranded-dna-and-rna-under-constant-stretching-forces-using-all-atom-molecular-dynamics
#8
Alberto Marin-Gonzalez, J G Vilhena, Ruben Perez, Fernando Moreno-Herrero
Multiple biological processes involve the stretching of nucleic acids (NAs). Stretching forces induce local changes in the molecule structure, inhibiting or promoting the binding of proteins, which ultimately affects their functionality. Understanding how a force induces changes in the structure of NAs at the atomic level is a challenge. Here, we use all-atom, microsecond-long molecular dynamics to simulate the structure of dsDNA and dsRNA subjected to stretching forces up to 20 pN. We determine all of the elastic constants of dsDNA and dsRNA and provide an explanation for three striking differences in the mechanical response of these two molecules: the threefold softer stretching constant obtained for dsRNA, the opposite twist-stretch coupling, and its nontrivial force dependence...
June 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28632382/manipulation-of-chain-conformation-for-optimum-charge-transport-pathway-in-conjugated-polymers
#9
Seolhee Jeon, Jung Hun Lee, Jai Il Park, Bonghyun Jo, Dong Ryeol Whang, Tae Kyu Ahn, Hui Joon Park, Sung Dong Kim, Wi Hyoung Lee, Bong-Gi Kim
Two different diketopyrrolopyrrole-based conjugated polymers (CPs) were designed and synthesized to investigate the effect of chain conformation on their molecular assembly. Conformation management was achieved by the incorporation of different linkers during polymerization. Using computational calculations and UV-vis absorption measurements, the resulting CPs were found to exhibit partly modulated chain geometry. Grazing incident X-ray diffraction experiment with a 2-dimensional detector revealed that PDPP-T having a planar chain conformation exhibited an edge-on type molecular arrangement, which evolved to a face-on type chain assembly when the planar geometry was altered to a slightly twisted one as in PDPP-BT...
June 20, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28632320/synthesis-optoelectronic-and-self-assembly-properties-of-diazadioxaacene-derivatives
#10
Jinchong Xiao, Huhang Pan, Jingdan Duan, Guixia Zhai, Pengcheng Jin, Xiaohui Zhao, Li Jiang
Two novel diazadioxaacene derivatives (ADOP and ADOQ) have been successfully synthesized and characterized. Their single crystal analyses disclose that molecule ADOP forms a twisted topology configuration, while ADOQ adopts a reclining chair architecture. Both of them emit strong blue fluorescence in organic solvents. Moreover, they can self assemble to form regular nanobelts and nanowires respectively via a simple surfactant-assisted method.
June 20, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28630675/how-geometric-frustration-shapes-twisted-fibres-inside-and-out-competing-morphologies-of-chiral-filament-assembly
#11
Douglas M Hall, Gregory M Grason
Chirality frustrates and shapes the assembly of flexible filaments in rope-like, twisted bundles and fibres by introducing gradients of both filament shape (i.e. curvature) and packing throughout the structure. Previous models of chiral filament bundle formation have shown that this frustration gives rise to several distinct morphological responses, including self-limiting bundle widths, anisotropic domain (tape-like) formation and topological defects in the lateral inter-filament order. In this paper, we employ a combination of continuum elasticity theory and discrete filament bundle simulations to explore how these distinct morphological responses compete in the broader phase diagram of chiral filament assembly...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28630669/straight-round-the-twist-frustration-and-chirality-in-smectics-a
#12
Elisabetta A Matsumoto, Randall D Kamien, Gareth P Alexander
Frustration is a powerful mechanism in condensed matter systems, driving both order and complexity. In smectics, the frustration between macroscopic chirality and equally spaced layers generates textures characterized by a proliferation of defects. In this article, we study several different ground states of the chiral Landau-de Gennes free energy for a smectic liquid crystal. The standard theory finds the twist grain boundary (TGB) phase to be the ground state for chiral type II smectics. However, for very highly chiral systems, the hierarchical helical nanofilament phase can form and is stable over the TGB...
August 6, 2017: Interface Focus
https://www.readbyqxmd.com/read/28629812/benthic-foraminifera-for-heavy-metal-pollution-monitoring-a-case-study-from-burullus-lagoon-of-egypt
#13
O H Orabi, A A El-Badry, A M Badr-ElDin
Sources of heavy metals pollution in the Burullus Lagoon include phosphate fertilizers, sewage and oil spills from fishing boats. The benthic species identified in this lagoon are Adelosina carinata striata (Wiesner), Quinqueloculina bosciana (d'Orbigny), Quinqueloculina seminulum (Linnaeus), Ammonia tepida (Cushman), Elphidium excavatum (Terquem). A. tepida is the most dominant species in the lagoon. It constitutes more than 97% of the total benthic foraminiferal assemblages reflecting tolerance to the very low salinity in the Burullus Lagoon...
June 16, 2017: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/28629739/twisting-cracks-in-bouligand-structures
#14
Nobphadon Suksangpanya, Nicholas A Yaraghi, David Kisailus, Pablo Zavattieri
The Bouligand structure, which is found in many biological materials, is a hierarchical architecture that features uniaxial fiber layers assembled periodically into a helicoidal pattern. Many studies have highlighted the high damage-resistant performance of natural and biomimetic Bouligand structures. One particular species that utilizes the Bouligand structure to achieve outstanding mechanical performance is the smashing Mantis Shrimp, Odontodactylus Scyllarus (or stomatopod). The mantis shrimp generates high speed, high acceleration blows using its raptorial appendage to defeat highly armored preys...
June 10, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28627031/the-influence-of-oxygen-atoms-on-conformation-and-%C3%AF-%C3%AF-stacking-of-ladder-type-donor-based-polymers-and-their-photovoltaic-properties
#15
Tong Qin, Yue Zang, Wei-Yun Bai, Kai Yao, Yun-Xiang Xu
A novel ladder-type donor pyran-bridged indacenodithiophene (IDTP) is developed by introducing two oxygen atoms into indacenodithiophene unit. IDTP possesses a twisted backbone and leads to facially asymmetric arrangement of side chains, resulting in enhanced local π-π stacking of according polymer poly[(5,5,11,11-tetrakis(4-octylphenyl)-5,11-dihydrothieno[2',3':5,6]pyrano[3,4-g]thieno[3,2-c]isochromene)-alt-4,7-(5-fluoro-2,1,3-benzothiadiazole)] (PIDTP)-FBT, which shows extended absorption range. Moreover, oxygen atoms render deeper highest occupied molecular orbital (HOMO) levels of poly[indacenodithiophene-alt-4,7-(5-fluoro-2,1,3-benzothiadiazole)] (PIDTP)-FBT compared with PIDT-FBT, therefore bringing a higher open-circuit voltage (Voc )...
June 19, 2017: Macromolecular Rapid Communications
https://www.readbyqxmd.com/read/28626382/a-symptomatic-coffee-bean-acute-sigmoid-volvulus
#16
Michael Scharl, Luc Biedermann
An acute sigmoid volvulus is due to the torsion of the sigmoid colon around its mesenteric axis. It mainly occurs in elderly patients and represents an abdominal emergency requiring urgent treatment. A 53-year-old male patient with severe craniocerebral injury and traumatic subarachnoidal bleeding 3 weeks prior presented on the ward with distended abdomen without abdominal pain, muscular defense, or resistances. He featured large volume diarrhea within the last few hours without signs of bleeding. A plain abdominal X-ray demonstrated a coffee bean sign indicating a sigmoid volvulus...
May 2017: Case Reports in Gastroenterology
https://www.readbyqxmd.com/read/28625047/asymmetric-synthesis-of-the-antiviral-diterpene-wickerol-a
#17
Shu-An Liu, Dirk Trauner
Wickerol A (1) is an unusual diterpene with remarkable activity against H1N1 influenza virus. Its tetracyclic skeleton contains three quaternary carbons and is marked by several syn-pentane interactions which force a six-membered ring into a twist-boat conformation. We present an asymmetric synthesis of wickerol A (1) that is based on a Jung Diels-Alder reaction, an intramolecular alkylation to complete the 6-5-6-6 ring system, and a conjugate addition, all of which overcome considerable steric strain. During the synthesis, we isolated an unusual cyclopropane, which presumably stems from a carbonium ion...
June 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28623840/on-the-spectral-properties-of-methyl-and-methoxy-derivatives-of-1-3-diphenyl-1h-pyrazolo-3-4-b-quinoxalines-experiment-and-dft-tddft-calculations
#18
P Gąsiorski, M Matusiewicz, E Gondek, T Uchacz, K Wojtasik, A Danel, Ya Shchur, A V Kityk
Paper reports the synthesis and spectroscopic studies of two novel 1,3-diphenyl pyrazoloquinoxaline (PQX) derivatives with 6-substituted methyl (MePQX) or methoxy (MeOPQX) side groups. The optical absorption and fluorescence emission spectra are recorded in solvents of different polarity. Other photophysical constants, such as the fluorescence lifetime and quantum yield, radiationless and radiative rate constants, electronic transition dipole moments, give complete characterization of MePQX and MeOPQX dyes as materials for potential luminescence or electroluminescence applications...
June 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28622542/on-the-mechanism-of-non-radiative-decay-of-blue-fluorescent-protein-chromophore-new-insight-from-the-excited-state-molecular-dynamics-simulations-and-potential-energy-calculations
#19
Li Zhao, Jian-Yong Liu, Pan-Wang Zhou
A detailed theoretical investigation based on the ab initio on-the-fly surface hopping dynamics simulations and potential energy surfaces calculations has been performed to unveil the mechanism of the photoinduced non-adiabatic relaxation process of the isolated blue fluorescent protein (BFP) chromophore in gas phase. The data analysis presents that the dominant reaction coordinate of the BFP chromophore is driven by a rotation motion around the CC double bridging bond, which is in remarkable difference with a previous result which supports a Hula-Twist rotation pattern...
June 6, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28622248/quantitative-perfusion-analysis-of-the-rectum-using-golden-angle-radial-sparse-parallel-magnetic-resonance-imaging-initial-experience-and-comparison-to-time-resolved-angiography-with-interleaved-stochastic-trajectories
#20
Ulrike I Attenberger, Jing Liu, Philipp Riffel, Johannes Budjan, Robert Grimm, Kai T Block, Stefan O Schoenberg, Xiaoying Wang, Daniel Hausmann
OBJECTIVES: Purpose of this study was to compare the quality of perfusion maps obtained from prototypical free-breathing magnetic resonance imaging (MRI) with continuous golden-angle radial sampling and iterative reconstruction (GRASP) to conventional acquisition using time-resolved angiography with interleaved stochastic trajectories (TWIST) in patients with rectal cancer. MATERIAL AND METHODS: Forty cases were included for retrospective analysis. Twenty of the patients received routine multiparametric MRI at 3 T for rectal cancer staging, including perfusion measurement with GRASP or TWIST (10 patients for each technique, including 5 prechemoradiation and 5 postchemoradiation)...
June 16, 2017: Investigative Radiology
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