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41.
Peter Rogl Subhash K. Naik Erwin Rudy 《Monatshefte für Chemie / Chemical Monthly》1977,108(6):1339-1352
The system VC0.88–HfC0.98–MoC was investigated by means of melting point, differential-thermoanalytical, X-ray diffraction and metallographic techniques on hot pressed and heat treated as well as melted alloy specimens and a constitutional diagram from 1500°C through the melting range established.The small miscibility gap within the HfC–MoC system (T
c=1630°C) interacts at lower temperatures with the solvus in a monotectoid-like reaction at 1575°C. Additions of VC to the HfC–MoC solid solution gradually increase its critical temperature.Solid state phase behaviour and melting behaviour was established within the isopleths VC0.88–MoC as well as within (V0.5Hf0.5)C–MoC and (V0.75Hf0.25)C–(Hf0.75Mo0.25)C.Phase equilibria within VC0.88–HfC–MoC are characterized by an extreme large miscibility gap at 1500°C connecting the VC–HfC and HfC–MoC systems.Originating at the VC–HfC binary an eutectic trough proceeds into the VC–HfC–MoC ternary with rising temperatures, connecting the maximum critical point of the disappearing miscibility gap [(V0.31Hf0.49Mo0.20)C] by a limiting tie line (2750±20°C). Isothermal sections have been calculated assuming regular solutions.With 5 Figures 相似文献
42.
Wagemans RW van Lenthe JH de Jongh PE van Dillen AJ de Jong KP 《Journal of the American Chemical Society》2005,127(47):16675-16680
Magnesium hydride is cheap and contains 7.7 wt % hydrogen, making it one of the most attractive hydrogen storage materials. However, thermodynamics dictate that hydrogen desorption from bulk magnesium hydride only takes place at or above 300 degrees C, which is a major impediment for practical application. A few results in the literature, related to disordered materials and very thin layers, indicate that lower desorption temperatures are possible. We systematically investigated the effect of crystal grain size on the thermodynamic stability of magnesium and magnesium hydride, using ab initio Hartree-Fock and density functional theory calculations. Also, the stepwise desorption of hydrogen was followed in detail. As expected, both magnesium and magnesium hydride become less stable with decreasing cluster size, notably for clusters smaller than 20 magnesium atoms. However, magnesium hydride destabilizes more strongly than magnesium. As a result, the hydrogen desorption energy decreases significantly when the crystal grain size becomes smaller than approximately 1.3 nm. For instance, an MgH2 crystallite size of 0.9 nm corresponds to a desorption temperature of only 200 degrees C. This predicted decrease of the hydrogen desorption temperature is an important step toward the application of Mg as a hydrogen storage material. 相似文献
43.
L. E. Toth F. Benesovsky H. Nowotny E. Rudy 《Monatshefte für Chemie / Chemical Monthly》1961,92(5):956-960
Zusammenfassung Der Dreistoff: Th–B–C wird mittels gesinterter und geschmolzener Proben röntgenographisch untersucht; eine Aufteilung der Phasenfelder wird gegeben. Es treten mindestens vier ternäre Verbindungen auf: ThB2C, ThBC, ThBC2 und Th2BC2. Ein Strukturvorschlag für ThB2C, hexagonal mit C 32-ähnlichem Typ, wird gemacht. Th2BC2 ist an Luft unbeständig, während sich die übrigen ternären Phasen als verhältnismäßig stabil erweisen.Mit 3 Abbildungen 相似文献
44.
45.
The compound V0.4Os0.6B2 was found to crystallize with ReB2-type structure. V2OsB2, Mo2OsB2, and W2OsB2 are isotypic with the crystal structure of Mo2IrB2. The crystal chemistry of complex borides with ReB2- and Mo2IrB2-type structure is discussed. 相似文献
46.
A ternary σ-phase (Cr0.39–0.57Mo0.47–0.29Si0.14) has been detected in the chromium—molybdenum—silicon system at 1500 °C. The novel σ-phase, which displays only a small degree of ordering, undergoes eutectoid decomposition at ca. 1200 °C, into (Cr, Mo)+(Cr,Mo)3Si. The relative stability bility of the ternary σ-phase and the non-existing binary σ-phases (Cr?Si, Mo?Si) were estimated from the observed equilibria. With respect to the coexistent phases there is an amount of 2500 cal/g atom metal necessary for stabilizing of the ternary σ-phases at 1500 °C. The slight deviation from completely random distribution reflects on the entropy change and there is fair agreement with the entropy change calculated from the temperature dependency of ΔG z, σ. 相似文献
47.
48.
Small changes with big effects: Tuning polymer properties with supramolecular interactions 下载免费PDF全文
Rudy J. Wojtecki Alshakim Nelson 《Journal of polymer science. Part A, Polymer chemistry》2016,54(4):457-472
For biological polymers like DNA and proteins, supramolecular interactions dictate the folding and assembly of the polymer chains. Advances in synthetic polymer chemistry enable the synthesis of polymers of defined length and composition, but the field has yet to reach the same level of sophistication as nature's polymers. However, the incorporation of just a few supramolecular interactions into a synthetic polymer chain can drastically change the manner in which the polymer assembles and interacts, thereby altering the properties of a polymeric material. This highlight will focus on approaches wherein a low‐density of supramolecular functionalities (<10 wt %) were used per polymer chain. How the selection of the appropriate supramolecular functionality (based on the directionality and strength of the interaction), along with the location of these groups on a polymer chain, can afford a spectrum of material properties has been highlighted. At one end, the supramolecular motif can dramatically alter the elasticity of a material, and at the other, the motif can have a more subtle effect like increasing the stability of a micelle. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 457–472 相似文献
49.
Paramaporn Chiewpattanakul Rudy Covis Régis Vanderesse Benjamas Thanomsub Emmanuelle Marie Alain Durand 《Colloid and polymer science》2010,288(9):959-967
Dextran-covered nanoparticles were produced by two different processes: emulsion/solvent evaporation and nanoprecipitation
for the encapsulation of monomyristin. The inner core was formed by poly(lactic acid) or by a hydrophobically modified dextran
(carrying n-decyl chains). According to the core materials and/or to the process, the average size of nanoparticles as well as the extent
of aggregate formation was modulated. It was shown that the presence of monomyristin induced significant modifications on
the characteristics of the resulting suspension (size and aggregate formation). Varying the matrix polymer as well as the
amount of monomyristin in the feed allowed obtaining nanoparticles with convenient size. The use of hydrophobically modified
dextran as the matrix material appeared promising. 相似文献
50.
Z. Rudy W. Cassing L. Jarczyk B. Kamys P. Kulessa O.W.B. Schult A. Strzałkowski 《The European Physical Journal A - Hadrons and Nuclei》1999,5(2):127-129
It is shown that the mass dependence of the Λ-lifetime in heavy hypernuclei is sensitive to the ratio of neutron-induced
to proton-induced non-mesonic decay rates R
n/R
p. A comparison of the experimental mass dependence of the lifetimes with the calculated ones for different values of R
n/R
p leads to the conclusion that this ratio is larger than 2 on the confidence level of 0.75. This suggests that the phenomenological
ΔI= 1/2 rule might be violated for the nonmesonic decay of the Λ-hyperon.
Received: 31 March 1999 相似文献