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191.
Francis J. G. Beltzer 《Colloid and polymer science》1911,9(2):76-81
Ohne ZusammenfassungIngénieur-Chimiste, Professeur de Chimie Industrielle. 相似文献
192.
Meade Bolton C. Kraus T. Leone Link Heraeus Flügge A. Pfeiffer E. Esmarch Carl Fränkel von Sehlen's M. Hochstetter G. Bischof Alex Köbrich O. Kasper Dupré Joseph Klein John Henry Smith J. W. Mallet's E. Reichardt Mayrhofer Leopold Spiegel Katharine J. Williams W. Ramsay A. B. Cooper Baeseler Nobbe Will W. Knop C. W. Heaton Thomas Stevenson Odling Tidy Crookes P. T. Austen Austen und Francis A. Wilber 《Fresenius' Journal of Analytical Chemistry》1888,27(1):77-84
Ohne Zusammenfassung 相似文献
193.
H. A. Freye A. Soltys M. Francis J. Fino F. Kaufman 《Analytical and bioanalytical chemistry》1937,111(7-8):281-283
194.
195.
Hidetsugu Horikawa Earl H. Dowell Francis C. Moon 《International Journal of Solids and Structures》1978,14(10):821-839
This study examines the possibility of controlling through feedback a thin cantilevered beam subjected to a nonconservative follower force. A converging frequency flutter instability which occurs in this model is similar to classical bending-torsion flutter of an aircraft wing. Because of the similar nature of the instabilities, the beam under the follower force can be a useful vehicle for investigating the fundamental aspects of stabilization of wing flutter by feedback control. A modal approach is used for obtaining the mathematical model and control laws. A standard root locus technique for simple analytical models is also used to understand and explain the control of the beam. Experiments are carried out to verify the validity of this theoretical model. Good correlation is shown between theoretically and experimentally determined stability boundaries as well as for modal frequency and damping variation with follower force. 相似文献
196.
Alexander Aerts Dr. Mohamed Haouas Dr. Tom P. Caremans Lana R. A. Follens Dr. Titus S. van Erp Dr. Francis Taulelle Dr. Jan Vermant Prof. Johan A. Martens Prof. Christine E. A. Kirschhock Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(9):2764-2774
Colloidal silicalite‐1 zeolite was crystallized from a concentrated clear sol prepared from tetraethylorthosilicate (TEOS) and aqueous tetrapropylammonium hydroxide (TPAOH) solution at 95 °C. The silicate speciation was monitored by using dynamic light scattering (DLS), synchrotron small‐angle X‐ray scattering (SAXS), and quantitative liquid‐state 29Si NMR spectroscopy. The silicon atoms were present in dissolved oligomers, two discrete nanoparticle populations approximately 2 and 6 nm in size, and crystals. On the basis of new insight into the evolution of the different nanoparticle populations and of the silicate connectivity in the nanoparticles, a refined crystallization mechanism was derived. Upon combining the reagents, different types of nanoparticles (ca. 2 nm) are formed. A fraction of these nanoparticles with the least condensed silicate structure does not participate in the crystallization process. After completion of the crystallization, they represent the residual silicon atoms. Nanoparticles with a more condensed silicate network grow until approximately 6 nm and evolve into building blocks for nucleation and growth of the silicalite‐1 crystals. The silicate network connectivity of nanoparticles suitable for nucleation and growth increasingly resembles that of the final zeolite. This new insight into the two classes of nanoparticles will be useful to tune the syntheses of silicalite‐1 for maximum yield. 相似文献
197.
Ignacio Alfonso Dr. Miriam Bru Dr. M. Isabel Burguete Dr. Eduardo García‐Verdugo Dr. Santiago V. Luis Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1246-1255
The self‐assembling abilities of several pseudopeptidic macrocycles have been thoroughly studied both in the solid (SEM, TEM, FTIR) and in solution (NMR, UV, CD, FTIR) states. Detailed microscopy revealed large differences in the morphology of the self‐assembling micro/nanostructures depending on the macrocyclic chemical structures. Self‐assembly was triggered by the presence of additional methylene groups or by changing from para to meta geometry of the aromatic phenylene backbone moiety. More interestingly, the nature of the side chain also plays a fundamental role in some of the obtained nanostructures, thus producing structures from long fibers to hollow spheres. These nanostructures were obtained in different solvents and on different surfaces, thus implying that the chemical information for the self‐assembly is contained in the molecular structure. Dilution NMR studies (chemical shift and self‐diffusion rates) suggest the formation of incipient aggregates in solution by a combination of hydrogen‐bonding and π–π interactions, thus implicating amide and aryl groups, respectively. Electronic spectroscopy further supports the π–π interactions because the compounds that lead to fibers show large hypochromic shifts in the UV spectra. Moreover, the fiber‐forming macrocycles also showed a more intense CD signature. The hydrogen‐bonding interactions within the nanostructures were also characterized by attenuated total‐reflectance FTIR spectroscopy, which allowed us to monitor the complete transition from the solution to the dried nanostructure. Overall, we concluded that the self‐assembly of this family of pseudopeptidic macrocycles is dictated by a synergic action of hydrogen‐bonding and π–π interactions. The feasibility and geometrical disposition of these interactions finally render a hierarchical organization, which has been rationalized with a proposal of a model. The understanding of the process at the molecular level has allowed us to prepare hybrid soft materials. 相似文献
198.
The rhombohedral modification of the thiospinel, CuZr1.86(1)S4, has been synthesized by the reaction of the constituent elements in an alkali metal halide flux and structurally characterized by single crystal X-ray diffraction techniques. The title compound crystallizes in the rhombohedral space group (#166, a=7.3552(2) Å, c=35.832(2) Å, V=1678.76(13) Å3, Z=12, and R/wR=0.0239/0.0624). The structure is composed of close packed S layers, with a stacking order of ?ABCBCABABCACAB?·along the c axis. The Zr and Cu atoms occupy the octahedral and tetrahedral holes between S layers, respectively. Three different kinds of S-M-S layers exist in the structure: layer I has fully occupied Zr and Cu sites, layer II has fully occupied Zr sites but no Cu, and layer III has partially occupied Zr and fully occupied Cu sites. Transport and optical properties indicate that the title compound is a small band gap (1.26 eV) n-type semiconductor. 相似文献
199.
The thermoelectric properties of Pb0.5Sn0.5Te doped with In at 1.0, 2.0, and 3.0×1019/cm3 and sintered at a high pressure and high temperature (HPHT) of 4.0 GPa and 800 or 900 °C, respectively, have been studied. All samples show p-type semiconducting behavior with positive thermopower. We find that HPHT sintering of conventionally synthesized materials improves their thermoelectric properties. The highest power factor is obtained for In doping of 2.0×1019/cm3 with 13.5 μW/cm K2 at 230 °C. The corresponding figure of merit is 1.43×10−3/K. This represents a twofold improvement in thermoelectric figure of merit, compared to the conventionally sintered materials reported in the literature. When exposed to 400 °C for 10 days, samples sintered at 900 °C exhibit more stable thermoelectric properties, while the properties of those sintered at 800 °C deteriorated. These results demonstrate that HPHT sintering is a viable and controllable way of tuning the thermoelectric properties of PbTe-based materials. 相似文献
200.
Jean-Daniel Compain Anne Dolbecq Jérôme Marrot Pierre Mialane Francis Sécheresse 《Comptes Rendus Chimie》2010,13(3):329-335
The reactivity of the [MoV2O4]2+ dinuclear unit with the [O3P(C(CH3)(OH))PO3]4? etidronate ligand has been investigated. Three complexes have been isolated and characterized by IR spectroscopy, elemental analysis and single crystal X-Ray diffraction studies. Structural determination of the tetranuclear compound (CN3H6)6[(MoV2O4)2(O3P(C(CH3)O)PO3)2]·12H2O (1) revealed that the hydroxo group of the etidronate ligand can be deprotonated in presence of MoV even in acidic media. It follows that its coordination mode thus differs from that of the methylenediphosphonate ligand [O3P(CH2)PO3]4?, which reactivity with MoV has been previously widely studied. In contrast, no such deprotonation of the hydroxo group is observed in the (NH4)18[(MoV2O4)6(OH)6(O3P(C(CH3)(OH))PO3)6]·35H2O complex 2. This species contains a dodecanuclear core analogous to the one previously found in the [(MoV2O4)6(OH)6(O3PCH2PO3)6]18? methylenediphosphonato polyanion. In 2, six interconnected {(MoV2O4)(O3P(C(CH3)(OH))PO3)} units form a cyclohexane-like ring in a chair conformation. In the (CN3H6)18Na3[(MoV2O4)7(O3P(C(CH3)(OH))PO3)7(CH3COO)7]·5CH3COONa 52H2O compound 3, seven {(MoV2O4)(O3P(C(CH3)(OH))PO3)(CH3COO)} units are connected, forming an almost planar tetradecanuclear wheel. This compound represents the largest homometallic MoV polyoxometalate cyclic system reported to date. Finally, 31P NMR studies revealed that only complex 1 is stable in aqueous solution. 相似文献