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81.
82.
Burdukova E Ishida N Shaddick T Franks GV 《Journal of colloid and interface science》2011,354(1):82-88
This work investigates the effect of temperature on the size of alumina aggregates formed by flocculation with temperature responsive Poly(N-Isopropylacrylamide)(PNIPAM). The results are discussed in terms of the effects of temperature on particle collision, particle adhesion and aggregate breakage. It was found that the size of alumina aggregates increases with increasing solution temperature. Particle/particle collision and aggregate breakage are largely unaffected by increasing solution temperature and therefore could not account for the change in aggregate size. The dominant factor in aggregate growth with increasing temperature was found to be the increase in the force of adhesion between alumina particles. The appearance of the adhesive force is triggered by the increase in temperature above the lower critical solution temperature of PNIPAM. 相似文献
83.
S. N. Yashkin E. A. Yashkina D. A. Svetlov Yu. N. Klimochkin 《Russian Chemical Bulletin》2013,62(5):1286-1292
The thermodynamic characteristics of adsorption (TCA) of isomeric molecules of methyl- and dimethylaminoadamantanes on the surface of the basis face of graphite were determined experimentally and calculated by the molecular statistical method. A relationship between the geometric structure of adsorbate molecules and the values of their TCA on graphitized thermal carbon black was established. The data obtained were used for the gas chromatographic identification of the amination products of a mixture of Z,E-isomers of 1,4-dimethyladamantane and 1,3-dimethyladamantane. 相似文献
84.
Dr. Svyatoslav Tolstikov Prof. Evgeny Tretyakov Dr. Sergey Fokin Dr. Elizaveta Suturina Prof. Galina Romanenko Dr. Artem Bogomyakov Dr. Dmitri Stass Dr. Alexander Maryasov Prof. Matvey Fedin Prof. Nina Gritsan Prof. Victor Ovcharenko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2793-2803
Spin‐labelled compounds are widely used in chemistry, physics, biology and the materials sciences but the synthesis of stable high‐spin organic molecules is still a challenge. We succeeded in synthesising heteroatom analogues of the 1,1,2,3,3‐pentamethylenepropane (PMP) diradicals with two nitronyl nitroxide ( DR1 ) and with two iminonitroxide ( DR2 ) fragments linked through the C(sp2) atom of the nitrone group. According to magnetic susceptibility measurements, EPR data and ab initio calculations at the (8,6)CASSCF and (8,6)NEVPT2 levels, DR1 and DR2 have singlet ground states. The singlet–triplet energy splitting (2J) is low (J/k=?7.4 for DR1 and ?6.0 K for DR2 ), which comes from the disjoint nature of these diradicals. The reaction of [Cu(hfac)2] with DR1 gives rise to different heterospin complexes in which the diradical acts as a rigid ligand, retaining its initial conformation. For the [{Cu(hfac)2}2( DR1 )(H2O)] complex, sufficiently strong ferromagnetic interactions (J1/k=42.7 and J2/k=14.1 K) between two coordinating CuII ions and DR1 were revealed. In [{Cu(hfac)2}2( DR1 )(H2O)][Cu(hfac)2(H2O)], the very strong and antiferromagnetic (J/k=?416.1 K) exchange interaction between one of the coordinating CuII ions and DR1 is caused by the very short equatorial Cu?O bond length (1.962 Å). 相似文献
85.
High‐Resolution 3D Proton MRI of Hyperpolarized Gas Enabled by Parahydrogen and Rh/TiO2 Heterogeneous Catalyst 下载免费PDF全文
Dr. Kirill V. Kovtunov Danila A. Barskiy Aaron M. Coffey Dr. Milton L. Truong Oleg G. Salnikov Alexander K. Khudorozhkov Elizaveta A. Inozemtseva Dr. Igor P. Prosvirin Prof. Valery I. Bukhtiyarov Dr. Kevin W. Waddell Dr. Eduard Y. Chekmenev Prof. Igor V. Koptyug 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(37):11636-11639
Several supported metal catalysts were synthesized, characterized, and tested in heterogeneous hydrogenation of propene with parahydrogen to maximize nuclear spin hyperpolarization of propane gas using parahydrogen induced polarization (PHIP). The Rh/TiO2 catalyst with a metal particle size of 1.6 nm was found to be the most active and effective in the pairwise hydrogen addition and robust, demonstrating reproducible results with multiple hydrogenation experiments and stability for ≥1.5 years. 3D 1H magnetic resonance imaging (MRI) of 1 % hyperpolarized flowing gas with microscale spatial resolution (625×625×625 μm3) and large imaging matrix (128×128×32) was demonstrated by using a preclinical 4.7 T scanner and 17.4 s imaging scan time. 相似文献
86.
Conclusions The radical arylation of S-allylisothiuronium chloride at the double bond is accompanied by fragmentation leading to the formation of allylarenes and, depending on the catalyst used, formamidine disulfide or arylisothiuronium compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 957–959, April, 1989. 相似文献
87.
Igor E. Uflyand Vladimir A. Zhinzhilo Elizaveta A. Mukhanova Egor V. Karyukov Marina A. Tautieva Daria A. Ostapenko Victoria E. Burlakova Gulzhian I. Dzhardimalieva 《无机化学与普通化学杂志》2019,645(11):758-767
In this study, new metal chelate monomers based on nickel(II) maleate and chelating N‐heterocycles (2,2′‐bipyridine and 1,10‐phenanthroline) were synthesized and characterized. A detailed analysis of the main stages and features of the kinetics of thermal transformations of metal chelate monomers was carried out. Core‐shell nanomaterials containing nanoparticles of nickel oxide and metallic nickel in a stabilizing nitrogen‐containing polymer matrix were obtained by thermolysis of these monomers. The composition, properties and structure of the nanomaterials were studied using IR spectroscopy, thermal analysis, X‐ray diffraction, atomic force microscopy, scanning electron microscopy, high‐resolution transmission electron microscopy, and energy dispersive X‐ray spectroscopy. The tribological characteristics of NiO nanoparticles as lubricant additives were studied using a pin‐on‐disc tribometer. The coefficient of friction (COF) is the lowest at the optimum concentration of nanoparticles and increasing the concentration above the optimum level leads to an increase in COF. 相似文献
88.
Baranov Vladimir V. Yatsenko Evgeniya L. Melnikova Elizaveta K. Nelyubina Yulia V. Kravchenko Angelina N. 《Chemistry of Heterocyclic Compounds》2019,55(2):160-166
Chemistry of Heterocyclic Compounds - A facile and efficient two-step synthetic route to previously inaccessible 1,3-unsubstituted 2-imino-5-oxooctahydroimidazo[4,5-d]-imidazol-1-ium iodides has... 相似文献
89.
90.
Homoleptic Two‐Coordinate Silylamido Complexes of Chromium(I), Manganese(I), and Cobalt(I) 下载免费PDF全文
Dr. C. Gunnar Werncke Dr. Elizaveta Suturina Philip C. Bunting Dr. Laure Vendier Prof. Jeffrey R. Long Prof. Dr. Mihail Atanasov Prof. Dr. Frank Neese Dr. Sylviane Sabo‐Etienne Dr. Sébastien Bontemps 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1668-1674
Anionic two‐coordinate complexes of first‐row transition‐metal(I) centres are rare molecules that are expected to reveal new magnetic properties and reactivity. Recently, we demonstrated that a N(SiMe3)2? ligand set, which is unable to prevent dimerisation or extraneous ligand coordination at the +2 oxidation state of iron, was nonetheless able to stabilise anionic two‐coordinate FeI complexes even in the presence of a Lewis base. We now report analogous CrI and CoI complexes with exclusively this amido ligand and the isolation of a [MnI{N(SiMe3)2}2]22? dimer that features a Mn?Mn bond. Additionally, by increasing the steric hindrance of the ligand set, the two‐coordinate complex [MnI{N(Dipp)(SiMe3)}2]? was isolated (Dipp=2,6‐iPr2‐C6H3). Characterisation of these compounds by using X‐ray crystallography, NMR spectroscopy, and magnetic susceptibility measurements is provided along with ligand‐field analysis based on CASSCF/NEVPT2 ab initio calculations. 相似文献