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71.
B. Berger A. J. Brammer E. L. Charsley J. J. Rooney S. B. Wirrington 《Journal of Thermal Analysis and Calorimetry》1997,49(3):1327-1335
Studies have been carried out on the boron-potassium perchlorate-nitrocellulose pyrotechnic system by DSC, simultaneous TG-DTA-mass spectrometry and chemical analysis. Quantitative measurements have been made on the exothermic pre-ignition reaction which took place above 360°C and the results have been compared with those obtained previously for the corresponding systems containing zirconium and a zirconium/nickel alloy. 相似文献
72.
Chungseok Choi Fengyi Zhao James L Hart Yuanzuo Gao Fabian Menges Conor L. Rooney Nia J. Harmon Bo Shang Zihao Xu Sa Suo Quynh Sam Judy J. Cha Tianquan Lian Hailiang Wang 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302152
We report a ternary hybrid photocatalyst architecture with tailored interfaces that boost the utilization of solar energy for photochemical CO2 reduction by synergizing electron and heat flows in the photocatalyst. The photocatalyst comprises cobalt phthalocyanine (CoPc) molecules assembled on multiwalled carbon nanotubes (CNTs) that are decorated with nearly monodispersed cadmium sulfide quantum dots (CdS QDs). The CdS QDs absorb visible light and generate electron-hole pairs. The CNTs rapidly transfer the photogenerated electrons from CdS to CoPc. The CoPc molecules then selectively reduce CO2 to CO. The interfacial dynamics and catalytic behavior are clearly revealed by time-resolved and in situ vibrational spectroscopies. In addition to serving as electron highways, the black body property of the CNT component can create local photothermal heating to activate amine-captured CO2, namely carbamates, for direct photochemical conversion without additional energy input. 相似文献
73.
Bo Shang Conor L. Rooney David J. Gallagher Bernie T. Wang Andrey Krayev Hadar Shema Oliver Leitner Nia J. Harmon Langqiu Xiao Colton Sheehan Samuel R. Bottum Elad Gross James F. Cahoon Thomas E. Mallouk Hailiang Wang 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215213
We report a precious-metal-free molecular catalyst-based photocathode that is active for aqueous CO2 reduction to CO and methanol. The photoelectrode is composed of cobalt phthalocyanine molecules anchored on graphene oxide which is integrated via a (3-aminopropyl)triethoxysilane linker to p-type silicon protected by a thin film of titanium dioxide. The photocathode reduces CO2 to CO with high selectivity at potentials as mild as 0 V versus the reversible hydrogen electrode (vs RHE). Methanol production is observed at an onset potential of −0.36 V vs RHE, and reaches a peak turnover frequency of 0.18 s−1. To date, this is the only molecular catalyst-based photoelectrode that is active for the six-electron reduction of CO2 to methanol. This work puts forth a strategy for interfacing molecular catalysts to p-type semiconductors and demonstrates state-of-the-art performance for photoelectrochemical CO2 reduction to CO and methanol. 相似文献
74.
The work summarized in this paper presents the first part of a three‐paper series on robust partial least squares (RPLS) regression. Motivated by recent research activities in this area, this part provides a detailed algorithmic analysis of associated techniques, showing that existing work (i) may not represent a true robust formulation of partial least squares (PLS), (ii) may lead to convergence problems or (iii) may be insensitive to a certain type of outlier. On the basis of this analysis, Part I introduces a new conceptual RPLS algorithm that overcomes the deficiencies of existing work. The second part of this work details this new RPLS technique, compares its peformance with existing RPLS methods and provides an analysis on the computational efficiency and sensitivity of these algorithms. Whilst the first two parts of this work discuss algorithmic developments of RPLS, the final part concentrates on practical issues of RPLS implementations. This third part is devoted to practitioners of chemistry and chemical engineering covering a wide range of applications involving a calibration experiment, the analysis of recorded data from an industrial debutanizer process and data from a number of Raman spectroscopy experiments. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
75.
Clare M. McArdle James G. Hamilton Edwina E. Law John J. Rooney 《Macromolecular rapid communications》1995,16(10):703-712
Ring-opening metathesis polymerization has been used to prepare a series of water soluble polymers based on the Diels-Alder adducts of furan and cyclopentadiene. Hydrophobically modified forms of these polymers were obtained either by copolymerization with 5-decylbicyclo[2.2.1]hept-2-ene, post-polymerization modification of the acid forms of the polymers with 1-decylamine or chain transfer to 1-hexadecene. Polymers were characterized by NMR specroscopy and viscometry. 相似文献
76.
A mathematical model is proposed for the process of vacuum superplasticforming. The model exploits the fact that in most industrialapplications the sheet aspect ratio (thickness/sheet width)is small. After an initial consideration of some of the moregeneral properties and the literature of superplastic materials,the elastic/plastic deformation of an internally-inflated thin-walledcylinder is examined. Plates of arbitrary geometry are thenconsidered. A quasisteady model in which the sheet moves througha sequence of steady states is developed. Some simplified closed-formsolutions are examined, but for general cases a system of nonlinearpartial differential equations must be solved numerically. Anefficient and accurate semi-explicit numerical scheme is proposedand a simplified stability analysis is presented; the methodis then used to compute properties of superplastic vacuum mouldedsheets in a number of practically motivated cases. 相似文献
77.
78.
The motion of a projectile in a uniform gravitational field loses its symmetry when a resisting force is present, essentially because Newton's law loses its reversibility. Allowing the magnitude of the resistance to depend arbitrarily on speed, the motion is governed by two coupled first-order non-linear differential equations. Though intractable to solve explicitly, these equations can be made to yield much qualitative information about the trajectory. The present paper focuses on the ascent and descent times of the projectile, providing a proof that the ascent and descent times are bounded, above and below respectively, by the corresponding (equal) times of a projectile reaching the same height without resistance. Additionally, the difference is shown to increase with the velocity of projection. Direct corollaries are two well known observed features of the motion: The time of ascent is always less than the time of descent, and the difference increases with the velocity of projection. For the bounds themselves, the resistance is only assumed to be positive, but to show that the difference increases with the velocity of projection requires the additional assumption that the resistance increases at least linearly with speed. 相似文献
79.
This paper examines all the possible types of thermomechanical constraints in finite-deformational elasticity. By a thermomechanical constraint we mean a functional relationship between a mechanical variable, either the deformation gradient or the stress, and a thermal variable, temperature, entropy or one of the energy potentials; internal energy, Helmholtz free energy, Gibbs free energy or enthalpy. It is shown that for the temperature-deformation, entropy-stress, enthalpy-deformation, and Helmholtz free energy-stress constraints equilibrium states are unstable, in the sense that certain perturbations of the equilibrium state grow exponentially. By considering the constrained materials as constitutive limits of unconstrained materials, it is shown that the instability is associated with the violation of the Legendre–Hadamard condition on the internal energy. The entropy-deformation, temperature-stress, internal energy-stress, and Gibbs free energy-deformation constraints do not exhibit this instability. It is proposed that stability of the rest state (or equivalently convexity of internal energy) is a necessary requirement for a model to be physically valid, and hence entropy-deformation, temperature-stress, internal energy-stress, and Gibbs free energy-deformation constraints are physical, whereas temperature-deformation constraints (including the customary notion of thermal expansion that density is a function of temperature only), entropy-stress constraints, enthalpy-deformation constraints, and Helmholtz free energy-stress constraints are not. 相似文献
80.
Xu S Podoprygorina G Böhmer V Ding Z Rooney P Rangan C Mittler S 《Organic & biomolecular chemistry》2007,5(3):558-568
Various calix[4]arene derivatives, fixed in the cone conformation by decylether groups and functionalized at their wide rim by urea residues, were synthesized. In two compounds (,) sulfur functions were attached to the urea groups via different spacers in order to allow binding to metal surfaces. While they exist as single molecules in polar solvents, tetraurea calix[4]arenes of this type () combine to form dimeric capsules in aprotic, apolar solvents. A solvent molecule is usually included in such a capsule, if no guest with a higher affinity is present. In the presence of an equimolar amount of the tetratosylurea, the exclusive formation of heterodimers, consisting of one molecule of and, is observed. The homo- and heterodimerization of the newly prepared derivatives, were studied by 1H NMR to establish the conditions under which they exhibit the desired dimerization behaviour. Self-assembled monolayers (SAMs) were formed using the single calix[4]arenes, and the heterodimeric capsules. Chloroform, dichloromethane and ferrocenium cations were used as guests in these immobilized heterodimeric capsules. The particular supramolecular architecture of the heterodimers should ensure that, after the immobilization on the metal surface, decomposition of the capsules and release or exchange of the guest is impossible or at least hindered. The self-assembly process and the stability of SAMs formed by capsules filled with ferrocenium cations in electrolyte solutions were tested with surface plasmon spectroscopy. The inclusion of guests, such as dichloromethane or ferrocenium, in the immobilized capsules were confirmed by classical surface plasmon spectroscopy, by gold nanoparticle absorption spectroscopy and by time-of flight secondary ion mass spectrometry (ToF-SIMS). The film stability and quality was tested by cyclic voltammetry. 相似文献