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61.
R. W. McMillan 《International Journal of Infrared and Millimeter Waves》1993,14(5):931-948
Several atmospheric hazards, including wind shear, clear-air turbulence, and wake vortices cause special problems for aircraft. These phenomena are usually characterized by a change in temperature relative to ambient, which may be detected by a millimeter wave radiometer operating on an absorption line in the atmosphere. Because of available componentry with excellent performance and relative freedom from interference by water vapor, the family of oxygen absorptions centered near 60 GHz is considered the best atmospheric feature on which the design of such an instrument could be based. This paper describes a multi-channel radiometer operating near 60 GHz which should be capable of detecting the hazards mentioned above as well as other potential dangers such as the passage of strong fronts and other severe weather. It is shown that a carefully designed instrument will be capable of measuring range to a hazard to an accuracy of about 5 percent and temperature difference to an accuracy of approximately half the actual measured difference, depending on range and temperature. An actual design is proposed, and graphs of expected performance are included. 相似文献
62.
63.
Song YF McMillan N Long DL Thiel J Ding Y Chen H Gadegaard N Cronin L 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(8):2349-2354
Grafting of C-6, C-16 and C-18 alkyl chains onto the hydrophilic Mn-Anderson clusters (compounds 2-4) has been achieved. Exchange of the tetrabutyl ammonium (TBA) with dimethyldioctadecyl ammonium (DMDOA) results in the formation of new polyoxometalate (POM) assemblies (compounds 5-6), in which the POM cores are covalently functionalized by hydrophilic alkyl-chains and enclosed by surfactant of DMDOABr. As a result, we have been able to design and synthesize POM-containing hydrophobic materials beyond surfactant encapsulation. In solid state, scanning electron and transmission electron microscopy (SEM and TEM) studies of the TBA salts of compounds 3 and 4 show highly ordered, uniform, reproducible assemblies with unique segmented rodlike morphology. SEM and TEM studies of the DMDOA salts of compounds 5 and 6 show that they form spherical and sea urchin 3D objects in different solvent systems. In solution, the physical properties of compound 5 and 6 (combination of surfactant-encapsulated cluster (SEC) and surface-grafted cluster (SGC)) show a liquid-to-gel phase transition in pure chloroform below 0 degrees C, which are much lower than other reported SECs. By utilizing light scattering measurements, the nanoparticle size for compounds 5 and 6 were measured at 5 degrees C and 30 degrees C, respectively. Other physical properties including differential scanning calorimetry have been reported. 相似文献
64.
McMillan N Smith LV de la Fuente JM Parenty AD Gadegaard N Pitt AR Thomson K Mackenzie C Kelly SM Cronin L 《Chemical communications (Cambridge, England)》2007,(25):2581-2583
N-Heterocyclic cations are incorporated into proteins using 5-(2-bromoethyl)phenanthridinium bromide, which selectively reacts with either cysteine or lysine residues, resulting in ethylphenanthridinium (Phen) or highly stable cyclised dihydro-imidazo-phenanthridinium (DIP) adducts respectively; these modifications have been found to manipulate the observed structure of lysozyme and bovine serum albumin by AFM. 相似文献
65.
Since the pioneering work of Bridgman it has been known that pressure affects the glass transition of polymers and liquid state viscosities. Usually the Tg and viscosity both increase as a function of pressure as expected from ‘free volume’ theories. However, H2O provided a notable exception in that the viscosity passes through a minimum at low temperature. It was thought that this might be linked to the anomalous thermal expansion behavior. However further research on geologically important aluminosilicate liquids revealed that they could show anomalous viscosity decreases with increasing pressure and this behavior is given a structural interpretation as five-fold coordinated Si4+ and Al3+ species are formed. Also the existence of polyamorphism or density-driven liquid–liquid phase transitions in certain systems can lead to anomalies in the Tg or η vs. P relations. This may be the case for H2O, for example. Current research is focusing on investigating structural changes in liquids and glasses at high pressure as the rich variety of behavior is becoming recognized. Both experimental studies and computer simulations are important as the underlying phenomonology is linked to changes in the glass or liquid structure as a function of densification. 相似文献
66.
Paul F. McMillan Jason R. Diefenbacher William T. Petuskey Richard W. Goettler 《Journal of Non》2009,355(28-30):1539-1551
We examined the solid-state water-soluble amorphous precursors that are formed by partial thermal decomposition of Al(NO3)3·9H2O (aluminum nitrate nonahydrate: ANN) using Raman and FTIR and solid-state magic-angle spinning NMR spectroscopy. We also studied the species formed in the aqueous alumosols formed by dissolution of the pre-ceramic precursors using 27Al NMR spectroscopy. Species identified in the alumosols included the Al3+(H2O)6 monomer, the [AlO4Al12(OH)24(H2O)12]7+(Al13) Keggin ion, and the Al30 polycation, [Al30O8(OH)56(H2O)24]18+, as well as various other oligomers or nanoparticles containing IV-, V- and VI-coordinated Al3+ ions. 相似文献
67.
Andrew J. Pugsley Andrea Sella Paul F. McMillan 《Journal of solid state chemistry》2011,184(9):2345-2352
We present results of an XAS and EXAFS study of the synthesis of Ge nanoparticles formed by a metathesis reaction between Mg2Ge and GeCl4 in diglyme (diethylene glycol dimethyl ether). The progress of the formation reaction and the products formed at various stages in the processing was characterised by TEM and optical spectroscopy as well as in situ XAS/EXAFS studies using specially designed reaction cells. 相似文献
68.
alpha-Keto alkynes react with CO and H(2) in the presence of catalytic quantities of the zwitterionic rhodium complex (eta(6)-C(6)H(5)BPh(3))(-)Rh(+)(1,5-COD) and triphenyl phosphite affording either the 2-, 2(3H)-, or 2(5H)-furanones in 61-93% yields. The cyclohydrocarbonylation is readily accomplished using substrates containing alkyl, aryl, vinyl, and alkoxy groups at the acetylenic terminal, as well as a variety of primary, secondary, and tertiary alkyl, aryl, and heteroaryl groups connected to the ketone functionality. Structural and electronic properties present in the starting materials mediate the chemo- and regioselectivity of the reaction. 相似文献
69.
70.
Paul F. McMillan Victoria Lees Gilles Montagnac Bruno Reynard Edward Bailey Furio Corà 《Journal of solid state chemistry》2009,182(10):2670-2677
The graphitic layered compound C6N9H3·HCl was prepared by reaction between melamine and cyanuric chloride under high pressure-high temperature conditions in a piston cylinder apparatus and characterised using SEM, powder X-ray diffraction, UV Raman and near-IR Fourier transform Raman spectroscopy with near-IR excitation. Theoretical calculations using density functional methods permitted evaluation of the mode of attachment of H atoms to nitrogen sites in the structure and a better understanding of the X-ray diffraction pattern. Broadening in the UV and near-IR FT Raman spectra indicate possible disordering of the void sites within the graphitic layers or it could be due to electron-phonon coupling effects. 相似文献