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https://www.readbyqxmd.com/read/28813058/fine-tuning-of-catalytic-and-sorption-properties-of-metal-organic-frameworks-via-in-situ-ligand-exchange
#1
Peng Wang, Kai Chen, Qing Liu, Huai-Wei Wang, Mohammad Azam, Saud I Al-Resayes, Yi Lu, Wei-Yin Sun
Metal-organic frameworks (MOFs) are gaining considerable attention not only because of their diverse structures but also due to their interesting properties and potential applications. However, fabrication of MOFs with desired structures and properties remains a great challenge. In this study, a strategy based on ligand exchange via single-crystal-to-single-crystal (SCSC) transformation has been undertaken, which can be used to achieve MOFs not available by direct synthesis and also to enrich the family of isoreticular MOFs...
August 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28813049/unprecedented-solvent-induced-inter-conversion-between-monomeric-and-dimeric-silylene-zinc-iodide-adducts
#2
Sandeep Yadav, Ekta Sangtani, Diksha Dhawan, Rajesh G Gonnade, Debashree Ghosh, Sakya S Sen
Usually, when a silylene reacts with a transition metal Lewis acid, it forms an adduct which could be either monomeric or dimeric. However, we present here that a silylene, [PhC(NtBu)2SiN(SiMe3)2] can form both monomeric [PhC(NtBu)2Si{N(SiMe3)2} → ZnI2]·THF (1) and dimeric [{PhC(NtBu)2}(N(SiMe3)2)SiZnI,(μ-I)]2 (2) adducts upon reaction with ZnI2. The formation of 1 and 2 relies upon the solvent used for the reaction or crystallization. When the crystallization is carried out in THF complex 1 is formed, however, when the reaction and crystallization are performed in acetonitrile complex 2 is obtained...
August 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28813044/short-bent-core-molecules-x-ray-polarization-dielectricity-texture-and-electro-optics-investigations
#3
S Torgova, S P Sreenilayam, Yu P Panarin, O Francescangeli, F Vita, J K Vij, E Pozhidaev, M Minchenko, C Ferrero, A Strigazzi
Bent-core liquid crystals based on 1,2,4-oxadiazole as a central unit have been the first mesogens to exhibit a ferroelectric response in the nematic phase. This behavior has been widely recognized as due to the presence of smectic-like polar cybotactic clusters permeating the nematic phase. Unfortunately, these compounds exhibited rather high melting points, about 120 °C, due to the presence of four benzene rings in the molecules. Here we describe the synthesis and physical characterization of a new series of BC mesogens, featuring the same bent core as the previous compounds but shorter outer substituents...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28813042/the-carotenoid-pathway-what-is-important-for-excitation-quenching-in-plant-antenna-complexes
#4
Kieran F Fox, Vytautas Balevičius, Jevgenij Chmeliov, Leonas Valkunas, Alexander V Ruban, Christopher D P Duffy
Plant light-harvesting is regulated by the Non-Photochemical Quenching (NPQ) mechanism involving the reversible formation of excitation quenching sites in the Photosystem II (PSII) antenna in response to high light. While the major antenna complex, LHCII, is known to be a site of NPQ, the precise mechanism of excitation quenching is not clearly understood. A preliminary model of the quenched crystal structure of LHCII implied that quenching arises from slow energy capture by Car pigments. It predicted a thoroughly quenched system but offered little insight into the defining aspects of this quenching...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28813019/grafting-modification-of-the-reactive-core-shell-particles-to-enhance-the-toughening-ability-of-polylactide
#5
Zhaokun Li, Shixin Song, Xuanchen Zhao, Xue Lv, Shulin Sun
In order to overcome the brittleness of polylactide (PLA), reactive core-shell particles (RCS) with polybutadiene as core and methyl methacrylate-co-styrene-co-glycidyl methacrylate as shell were prepared to toughen PLA. Tert-dodecyl mercaptan (TDDM) was used as chain transfer agent to modify the grafting properties (such as grafting degree, shell thickness, internal and external grafting) of the core-shell particles. The introduction of TDDM decreased the grafting degree, shell thickness and the Tg of the core phase...
August 16, 2017: Materials
https://www.readbyqxmd.com/read/28813006/samarium-monosulfide-sms-reviewing-properties-and-applications
#6
REVIEW
Andreas Sousanis, Philippe F Smet, Dirk Poelman
In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducting and metallic states could be exploited in several applications, such as high density optical storage and memory materials, thermovoltaic devices, infrared sensors and more...
August 16, 2017: Materials
https://www.readbyqxmd.com/read/28812902/charge-effects-on-the-efflorescence-in-single-levitated-droplets
#7
Gunter Hermann, Yan Zhang, Bernhard Wassermann, Henry Fischer, Marcel Quennet, Eckart Ruehl
The influence of electrical excess charges on the crystallization from supersaturated aqueous sodium chloride solutions is reported. This is accomplished by efflorescence studies on single levitated microdroplets using optical and electrodynamic levitation. Specifically, a strong increase in efflorescence humidity is observed as a function of the droplet's negative excess charge, ranging up to -2.1 pC, with a distinct threshold behavior, increasing the relative efflorescence humidity, at which spontaneous nucleation occurs, from 44% for the neutral microparticle to 60%...
August 16, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28812896/free-energy-of-nucleation-and-interplay-between-size-and-composition-in-cuni-systems
#8
Solene Bechelli, Brittany Gonzalez, Vincent Piquet, Ilham Essafri, Caroline Desgranges, Jerome Delhommelle
Using molecular simulation, we shed light on the crystal nucleation process in systems of Cu, Ni and their nanoalloy. For each system, we simulate the formation of the crystal nucleus along the entire nucleation pathway and determine the free energy barrier overcome by the system to form a critical nucleus. Comparing the results obtained for the pure metals to those for the nanoalloy, we analyze the impact of alloying on the free energy of nucleation, as well as on the size and structure of the crystal nucleus...
August 16, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28812880/an-exceptionally-narrow-band-gap-%C3%A2-4-ev-silicate-predicted-in-the-cubic-perovskite-structure-basio3
#9
Hidenori Hiramatsu, Hitoshi Yusa, Ryo Igarashi, Yasuo Ohishi, Toshio Kamiya, Hideo Hosono
The electronic structures of 35 A(2+)B(4+)O3 ternary cubic perovskite oxides, including their hypothetical chemical compositions, were calculated by a hybrid functional method with the expectation that peculiar electronic structures and unique carrier transport properties suitable for semiconductor applications would be hidden in high-symmetry cubic perovskite oxides. We found unique electronic structures of Si-based oxides (A = Mg, Ca, Sr, and Ba, and B = Si). In particular, the unreported cubic BaSiO3 has a very narrow band gap (4...
August 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28812879/germanium-and-tin-monoxides-trapped-by-oxophilic-germylene-and-stannylene-ligands
#10
Yunxia Gao, Ying Yang, Wenjun Zheng, Yuanyuan Su, Xiang Zhang, Herbert W Roesky
Germanium and tin monoxides (MO, M = Ge, Sn) were trapped by the 1,2,4-diazaphospholide-based germylene and stannylene M[3,5-tBu2dp]2 (M = Ge (2), Sn (3)), resulting in the Lewis acid-base adduct of composition M(μ-O)[M{η(1)(N)-(3,5-tBu2dp)}2]2 (M = Ge (4), Sn (5)). Compounds 4 and 5 were characterized by single-crystal X-ray structural analysis. The bonding features of 4 and 5 were supported by DFT calculations.
August 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28812877/scru2b3-and-sc2rub6-borides-featuring-a-2d-infinite-boron-clustering
#11
Leonid P Salamakha, Oksana Sologub, Berthold Stöger, Peter Franz Rogl, Monika Waas, Volodymyr B Kapustianyk, Ernst Bauer
Two borides, ScRu2B3 and Sc2RuB6, were obtained by argon-arc melting of the elements followed by annealing at 800 °C. ScRu2B3 exhibits a new structure type with the space group Cmcm (a = 3.0195(2) Å, b = 15.4056(8) Å, c = 5.4492(3) Å; single crystal X-ray data; RF(2) = 0.0105). Sc2RuB6 adopts the Y2ReB6-type structure (space group Pbam; a = 8.8545(2) Å, b = 11.1620(3) Å, c = 3.4760(1) Å; single crystal X-ray data; RF(2) = 0.0185). ScRu2B3 displays an unusual intergrowth of CeCo3B2- and AlB2-related slabs; a striking feature is a boat configuration of puckered boron hexagons within infinite graphite like boron layers (6(3) nets)...
August 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28812751/hydrogen-bonded-rosettes-comprising-%C3%AF-conjugated-systems-as-building-blocks-for-functional-one-dimensional-assemblies
#12
Bimalendu Adhikari, Xu Lin, Mitsuaki Yamauchi, Hayato Ouchi, Keisuke Aratsu, Shiki Yagai
Hydrogen-bonded supermacrocycles (rosettes) are attractive disk-shaped noncovalent synthons for extended functional columnar nanoassemblies. They can serve not only as noncovalent monomer units for supramolecular polymers and discrete oligomers in a dilute solution but also as constituent entities for soft matters such as gels and lyotropic/thermotropic liquid crystals. However, what are the merits of using supramolecular rosettes instead of using expanded π-conjugated covalent molecules? This review covers the self-assembly of photochemically and electrochemically active π-conjugated molecules through the formation of supramolecular rosettes via directional complementary multiple hydrogen-bonding interactions...
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28812737/human-exposure-and-sensitivity-to-globally-extreme-wildfire-events
#13
David M J S Bowman, Grant J Williamson, John T Abatzoglou, Crystal A Kolden, Mark A Cochrane, Alistair M S Smith
Extreme wildfires have substantial economic, social and environmental impacts, but there is uncertainty whether such events are inevitable features of the Earth's fire ecology or a legacy of poor management and planning. We identify 478 extreme wildfire events defined as the daily clusters of fire radiative power from MODIS, within a global 10 × 10 km lattice, between 2002 and 2013, which exceeded the 99.997th percentile of over 23 million cases of the ΣFRP 100 km(-2) in the MODIS record. These events are globally distributed across all flammable biomes, and are strongly associated with extreme fire weather conditions...
February 6, 2017: Nature ecology & evolution
https://www.readbyqxmd.com/read/28812408/calcium-pyrophosphate-deposition-disease-a-frequent-finding-in-patients-with-long-standing-erosive-gout
#14
B Ankli, D Kyburz, A Hirschmann, T Hügle, T Manigold, C T Berger, T Daikeler
OBJECTIVE: To characterize patients with both monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in their synovial fluid (SF). METHOD: Forty-nine gout patients with acute arthritis were included. Those patients with MSU crystals only in their SF were compared to those patients with both MSU and CPP crystals in their SF. RESULTS: A total of 36 out of 49 patients (73.5%) had only MSU crystals, whereas 13 out of 49 (26.5%) had both MSU and CPP crystals in their SF...
August 16, 2017: Scandinavian Journal of Rheumatology
https://www.readbyqxmd.com/read/28812278/monomer-dependent-secondary-nucleation-in-amyloid-formation
#15
REVIEW
Sara Linse
Secondary nucleation of monomers on the surface of an already existing aggregate that is formed from the same kind of monomers may lead to autocatalytic amplification of a self-assembly process. Such monomer-dependent secondary nucleation occurs during the crystallization of small molecules or proteins and self-assembled materials, as well as in protein self-assembly into fibrous structures. Indications of secondary nucleation may come from analyses of kinetic experiments starting from pure monomers or monomers supplemented with a low concentration of pre-formed aggregates (seeds)...
August 15, 2017: Biophysical Reviews
https://www.readbyqxmd.com/read/28812182/rheological-characterization-of-molten-polymer-drug-dispersions-as-a-predictive-tool-for-pharmaceutical-hot-melt-extrusion-processability
#16
Jeroen Van Renterghem, Chris Vervaet, Thomas De Beer
PURPOSE: The aim of this study was to investigate (i) the influence of drug solid-state (crystalline or dissolved in the polymer matrix) on the melt viscosity and (ii) the influence of the drug concentration, temperature and shear rate on polymer crystallization using rheological tests. METHODS: Poly (ethylene oxide) (PEO) (100.000 g/mol) and physical mixtures (PM) containing 10-20-30-40% (w/w) ketoprofen or 10% (w/w) theophylline in PEO were rheologically characterized...
August 15, 2017: Pharmaceutical Research
https://www.readbyqxmd.com/read/28812090/zero-charged-catanionic-lamellar-liquid-crystals-doped-with-fullerene-c60-for-potential-applications-in-tribology
#17
Mengjun Chen, Baoyong Liu, Xiaolin Wang, Yanxu Fu, Jingcheng Hao, Hongguang Li
The formation of lamellar liquid crystals (LLCs) has been demonstrated in a few salt-free catanionic surfactant systems and their properties have been well documented. However, examples of their combination with other materials are relatively rare. Herein, a salt-free zero-charged catanionic surfactant with low chain melting temperature was prepared by mixing equimolar tetradecyltrimethylammonium oxide (TTAOH) and oleic acid (OA) in water, and its concentration-dependent aggregate transition was investigated...
August 16, 2017: Soft Matter
https://www.readbyqxmd.com/read/28812085/high-tc-superconducting-phases-in-organic-molecular-intercalated-iron-selenides-synthesis-and-crystal-structures
#18
Shifeng Jin, Xiao Fan, Xiaozhi Wu, Ruijin Sun, Hui Wu, Qingzhen Huang, Chenlong Shi, Xuekui Xi, Zhilin Li, Xiaolong Chen
Hybrid iron-based superconductors were synthesized by sonochemical insertion of organic molecules into FeSe layers. High quality of the samples first enabled reliable phase identifications and three structure types were discovered. Structure determination based on neutron data further facilitated the understanding of their structural stability, doping levels and temperature driven structural transitions.
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28812064/chiral-cobalt-ii-complex-catalyzed-friedel-crafts-aromatization-for-the-synthesis-of-axially-chiral-biaryldiols
#19
Chaoran Xu, Haifeng Zheng, Bowen Hu, Xiaohua Liu, Lili Lin, Xiaoming Feng
An efficient atroposelective synthesis of axially chiral biaryldiols via asymmetric Friedel-Crafts aromatization between p-quinones and 2-naphthols was developed. A chiral cobalt(ii) complex of N,N'-dioxide enabled the process to generate axially chiral biaryldiols in up to 98% yield and 95% ee. A large range of substituents at different positions of p-quinones and 2-naphthols was tolerable. The configuration of the product and the chiral N,N'-dioxide-Co(ClO4)2 catalyst was identified by X-ray crystal diffraction analysis and a possible catalytic model was suggested...
August 16, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28811699/cystinuria-crystals-that-make-a-baby-cry
#20
Dhiraj J Trivedi, Vijayetha P Patil, Pramod S Kamble
Cystinuria is a common aminoaciduria due to a COAL transporter defect in renal tubular epithelium. Increased level of cystine in urine with occasional cystine crystal can be diagnostic. With reference to clinical examinations, symptoms and laboratory reports we present a case of primary cystinuria. Prevention of complication in cystinuric relies on detection at early stage and targeting treatment towards maintaining low level of urinary cystine level.
July 2017: Indian Journal of Clinical Biochemistry: IJCB
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