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131.
Dynamic interfacial tension values obtained by drop volume tensiometry will be affected under certain experimental conditions by the formation of a neck between the drop and the capillary tip. This phenomenon must be accounted for to obtain accurate values of interfacial tension. In this work, neck formation for a water–mineral oil system is studied under conditions where hydrodynamic effects can be neglected. A model originally developed for the determination of the surface tension of a suspended drop is modified for application to dynamic interfacial tensions of surfactant-containing liquids. The model relates apparent values of interfacial tension calculated from drops possessing necks to actual values. Experiments with Span 80 (sorbitan monooleate) and sodium dodecyl sulfate (SDS) surfactants in a mineral oil–water system are used to test the validity of the developed model. For the small tip diameter used, good agreement is obtained for Span 80 up to the critical micelle concentration, and for low concentrations of SDS, when the surfactant adsorption is diffusion-limited. In both cases, the neck diameter of the growing drop can be considered constant over the range of dynamic interfacial tensions tested. 相似文献
132.
Francisco García-Moreno Paul H. Kamm Tillmann R. Neu John Banhart 《Journal of synchrotron radiation》2018,25(5):1505-1508
An experimental setup has been developed that allows for capturing up to 25 tomograms s?1 using the white X‐ray beam at the experimental station EDDI of BESSY II, Berlin, Germany. The key points are the use of a newly developed, precise and fast rotation stage, a very efficient scintillator and a fast CMOS camera. As a first application, the foaming of aluminium alloy granules at 923 K was investigated in situ. Formation and growth of bubbles in the liquid material were observed and found to be influenced by the limited thermal conductivity in the bulk granules. Changes that took place between two tomographic frames separated in time by 39 ms could be detected and analysed quantitatively. 相似文献
133.
Prof. Dr. Tomoaki Tanase Dr. Kanako Nakamae Haruka Miyano Prof. Dr. Yasuyuki Ura Prof. Dr. Yasutaka Kitagawa Dr. Shiho Yada Prof. Dr. Tomokazu Yoshimura Prof. Dr. Takayuki Nakajima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(47):12078-12103
A series of the octapalladium chains supported by meso-Ph2PCH2P(Ph)CH2P(Ph)CH2PPh2 (meso-dpmppm) ligands, [Pd8(meso-dpmppm)4(L)2](BF4)4 (L=none ( 1 ), solvents: CH3CN ( 2 a ), dmf ( 2 b ), dmso ( 2 c ), RN≡C: R=Xyl ( 3 a ), Mes ( 3 b ), Dip ( 3 c ), tBu ( 3 d ), Cy ( 3 e ), CH3(CH2)7 ( 3 f ), CH3(CH2)11 ( 3 g ), CH3(CH2)17 ( 3 h )) and [Pd8(meso-dpmppm)4(X)2](BF4)2 (X=Cl ( 4 a ), N3 ( 4 b ), CN ( 4 c ), SCN ( 4 d )), were synthesized by using 2 a as a stable good precursor, and characterized by spectroscopic (IR, 1H and 31P NMR, UV-vis-NIR, ESI-MS) measurements and X-ray crystallographic analyses (for 1 , 2 a , b , 3 a , b , e , f , 4 a – d ). On the basis of DFT calculations on the X-ray determined structure of 2 b ( [2b-Pd8]4+ ) and the optimized models [Pd8(meso-Ph2PCH2P(H)CH2P(H)CH2PH2)4(CH3CN)2]4+ ( [Pd8Ph8]4+ ) and [Pd8(meso-H2PCH2P(H)CH2P(H)CH2PH2)4(CH3CN)2]4+ ( [Pd8H8]4+ ), with and without empirically calculating dispersion force stabilization energy (B3LYP-D3, B3LYP), the formation energy between the two Pd4 fragments is assumed to involve mainly noncovalent interactions (ca. −70 kcal/mol) with four sets of interligand C−H/π interactions and Pd⋅⋅⋅Pd metallophilic one, while electron shared covalent interactions are almost canceled out within the Pd8 chain. All the compounds isolated are stable in solution and exhibit characteristic absorption at ∼900 nm, which is assignable to a spin allowed HOMO to LUMO transition, and shows temperature dependent intensity change with variable absorption coefficients presumably due to coupling with some thermal vibrations. The structures and electronic states of the Pd8 chains are found finely tunable by varying the terminal capping ligands. In particular, theoretical calculations elucidated that the HOMO-LUMO energy gap is systematically related to the central Pd−Pd distance (2.7319(6)–2.7575(6) Å) by two ways with neutral ligands L ( 1 , 2 , 3 ) and with anionic ligands X ( 4 ), which are reflected on the NIR absorption energy of 867–954 nm. The isocyanide terminated Pd8 complexes ( 3 ) further reacted with excess of RNC (6 eq) to afford the Pd4 complexes, [Pd4(meso-dpmppm)2(RNC)2](BF4)2 ( 13 ), and the cyclic voltammograms of 2 a (L=CH3CN), 3 , and 13 (R=Xyl, Mes, tBu, Cy) demonstrated wide range redox behaviors from 2{Pd4}4+ to 2{Pd4}0 through 2{Pd4}2+↔{Pd8}4+, {Pd8}3+, and {Pd8}2+ strings. The oxidized complexes, [Pd4(meso-dpmppm)2(RNC)3](BF4)4 ( 16 ), were characterized by X-ray analyses, and the two-electron reduced chain of [Pd8(meso-dpmppm)4](BF4)2 ( 7 ) was analyzed by spectroscopic and electrochemical techniques and DFT calculations. Reactions of 2 a with 1 equiv. of aromatic linear bisisocyanide (BI) in CH2Cl2 deposited insoluble coordination polymers, {[Pd8(meso-dpmppm)4(BI)](BF4)4}n ( 5 ), and interestingly, they were soluble in acetonitrile, 31P{1H} and 1H DOSY NMR spectra as well as SAXS curves suggesting that the coordination polymers may exist in acetonitrile as dynamically 1D self-assembled coordination polymers comprising ca. 50 units of the Pd8 rod averaged within the timescale. 相似文献
134.
Yuying Qu Yingchun Li Xiaoli Tan Weixiang Zhai Dr. Guifang Han Dr. Jingli Hou Prof. Guoquan Liu Prof. Yuguang Song Prof. Yangping Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(33):7888-7895
Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications as spin probes/labels for EPR spectroscopy and imaging, and as polarizing agents for dynamic nuclear polarization. The high hydrophilicity of TAM radicals is essential for their biomedical applications. However, the synthesis of hydrophilic TAM radicals (e.g., OX063) is extremely challenging and has only been reported in the patent literature, to date. Herein, an efficient synthesis of a highly water-soluble TAM radical bis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)-mono-(8-carboxyl-2,2,6,6-tetrakis(2-hydroxyethyl)benzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)methyl (TFO), which contains four additional hydroxylethyl groups, relative to the Finland trityl radical CT-03, is reported. Similar to OX063, TFO exhibits excellent properties, including high water solubility in phosphate buffer, low log P, low pKa, long relaxation times, and negligible binding with bovine serum albumin. On the other hand, TFO has a sharper EPR line and higher O2 sensitivity than those of OX063. Therefore, in combination with its facile synthesis, TFO should find wide applications in magnetic resonance related fields and this synthetic approach would shed new light on the synthesis of other hydrophilic TAM radicals. 相似文献
135.
Multipod structures of lamellae‐forming diblock copolymers in three‐dimensional confinement spaces: Experimental observation and computer simulation 下载免费PDF全文
Takeshi Higuchi Marco Pinna Andrei V. Zvelindovsky Hiroshi Jinnai Hiroshi Yabu 《Journal of Polymer Science.Polymer Physics》2016,54(17):1702-1709
The three‐dimensional (3D) confinement effect on the microphase‐separated structure of a diblock copolymer was investigated both experimentally and computationally. Block copolymer nanoparticles were prepared by adding a poor solvent into a block copolymer solution and subsequently evaporating the good solvent. The 3D structures of the nanoparticles were quantitatively determined with transmission electron microtomography (TEMT). TEMT observations revealed that various complex structures, including tennis‐ball, mushroom‐like, and multipod structures, were formed in the 3D confinement. Detailed structural analysis, showed that one block of the diblock copolymer slightly prefers to segregate into the particle surface compared with the other block. The observed structures were further elaborated using cell dynamics computer simulation. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1702–1709 相似文献
136.
An asymptotic‐preserving (AP) scheme is efficient in solving multiscale problems where kinetic and hydrodynamic regimes coexist. In this article, we extend the BGK‐penalization‐based AP scheme, originally introduced by Filbet and Jin for the single species Boltzmann equation (Filbet and Jin, J Comput Phys 229 (2010) 7625–7648), to its multispecies counterpart. For the multispecies Boltzmann equation, the new difficulties arise due to: (1) the breaking down of the conservation laws for each species and (2) different convergence rates to equilibria for different species in disparate masses systems. To resolve these issues, we find a suitable penalty function—the local Maxwellian that is based on the mean velocity and mean temperature and justify various asymptotic properties of this method. This AP scheme does not contain any nonlinear nonlocal implicit solver, yet it can capture the fluid dynamic limit with time step and mesh size independent of the Knudsen number. Numerical examples demonstrate the correct asymptotic‐behavior of the scheme. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2013 相似文献
137.
138.
Elena Akhmatskaya José M. Asua 《Journal of polymer science. Part A, Polymer chemistry》2012,50(7):1383-1393
Modification of the polymer–polymer interfacial tension is a way to tailor‐make particle morphology of waterborne polymer–polymer hybrids. This allows achieving a broader spectrum of application properties and maximizing the synergy of the positive properties of both polymers, avoiding their drawbacks. In situ formation of graft copolymer during polymerization is an efficient way to modify the polymer–polymer interfacial tension. Currently, no dynamic model is available for polymer–polymer hybrids in which a graft copolymer is generated during polymerization. In this article, a novel model based on stochastic dynamics is developed for predicting the dynamics of the development of particle morphology for composite waterborne systems in which a graft copolymer is produced in situ during the process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
139.
Z. Šikić 《International Journal of Mathematical Education in Science & Technology》2013,44(6):923-927
By stretching the area under the curve x α it is shown to be of the form x α + 1 p(α). Geometry is then used to prove p(α) = 1/(α + 1). 相似文献
140.
GEORGE JOHN HIROYUKI MINAMIKAWA MITSUTOSHI MASUDA TOSHIMI SHIMIZU 《Liquid crystals》2013,40(6):747-749
Two novel aryl glycosides were synthesized, which varied in the extent of unsaturation in the lipophilic part, from plant/crop-based renewable resource materials. Their liquid crystalline properties were characterized by optical polarizing microscopy, differential scanning calorimetry and X-ray diffraction. All the mesophases are identified as lamellar in structure. 相似文献