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1.
M. T. Viciosa J. Quiles Hoyo M. Dionísio J. L. Gómez Ribelles 《Journal of Thermal Analysis and Calorimetry》2007,90(2):407-414
Temperature modulated differential scanning calorimetry (TMDSC) is used to study the kinetics of the free radical isothermal polymerization of triethyleneglycol dimethacrylate (TEGDMA). Azo-bis-isobutironitrile was used as initiator. The polymerization’s temperature is lower than the final glass transition temperature of the polymer network. The measurement of the average heat flow released and the heat capacity during the reaction allows identifying the different stages of the reaction. The presence of double peaks in the heat flow is ascribed to the autoacceleration. The influence of temperature, measuring conditions and oxygen are described. Vitrification is detected by the drop in heat capacity. It occurs at increasing conversion rates for increasing temperatures. After vitrification, the diffusion-controlled reaction continues. 相似文献
2.
Kashiwagi T Ohkoshi S Seino H Mizobe Y Hashimoto K 《Journal of the American Chemical Society》2004,126(16):5024-5025
We have prepared a pillared layer magnetic material containing a noncoordinated aromatic molecule, [{MnII(pyrimidine)(H2O)}2{MnII(H2O)2}{WV(CN)8}2](pyrimidine)2.2H2O. This compound has one-dimensional channels (6.2 x 2.1 A) that are occupied by noncoordinated pyrimidine. The magnetization versus temperature plots showed the magnetic phased transition temperature (TC) was 47 K. The magnetization versus external magnetic field plots showed that the saturation magnetization (MS) value was 13.0 muB at 2 K. This MS value indicates that an antiferromagnetic interaction operates between the WV (S = 1/2) and MnII (S = 5/2) ions. The magnetic hysteresis loop showed that the coercive field (HC) was 17 G at 2 K. 相似文献
3.
Yasushi Mizobe Reiko Ono Yasuzo Uchida Masanobu Hidai Meguru Tezuka Suehiro Moue Atsuhiko Tsuchiya 《Journal of organometallic chemistry》1980,204(3):377-385
Diazoalkane complexes of type [MF(NNCRR′)(dpe)2][BF4] (M = Mo or W; dpe = Ph2PCH2CH2PPh2), which are easily derived from bis(dinitrogen) complexes [M(N2)2(dpe)2], undergo consecutive one- and two-electron oxidations and reductions under voltammetric conditions at a platinum electrode. The ESR spectra of the species generated by the controlled potential electrolysis show that primary oxidation occurred on the metal atom (M = Mo) and reduction on the two nitrogen atoms in the diazoalkane ligands (M = Mo or W). 相似文献
4.
A stepwise reaction of p-tert-butylthiacalix[4]arene (TC4A-(OH)(4)) with [CpTiCl3]-NEt(3) and cis-[Mo(N(2))(2)(PMe(2)Ph)(4)] afforded a new Ti-Mo heterobimetallic complex [TC4A-(O)(4)Ti(micro2-C(5)H(5))MoH(PMe(2)Ph)(2)] which shows an unusual alpha-agostic micro2-eta5:eta2-coordination of a cyclopentadienyl ligand. 相似文献
5.
Y. Pesheva N. Abadzhjieva E. Vrachnou Y. Kovanis V. Rives C. del Hoyo D. Klissurski 《Reaction Kinetics and Catalysis Letters》1994,53(2):283-288
Methanol oxidation on V2O5 and V2O5–MoO3 catalysts supported on montmorillonite has been studied in the temperature range of 250–500°C. The V2O5–MoO3 containing sample shows higher selectivity towards formaldehyde formation than the V2O5 catalyst. 相似文献
6.
The generation of heterobimetallic complexes with two or three bridging sulfido ligands from mononuclear tris(sulfido) complex of tungsten [Et(4)N][(Me(2)Tp)WS(3)] (1; Me(2)Tp = hydridotris(3,5-dimethylpyrazol-1-yl)borate) and organometallic precursors is reported. Treatment of 1 with stoichiometric amounts of metal complexes such as [M(PPh(3))(4)] (M = Pt, Pd), [(PtMe(3))(4)(micro(3)-I)(4)], [M(cod)(PPh(3))(2)][PF(6)] (M = Ir, Rh; cod = 1,5-cyclooctadiene), [Rh(cod)(dppe)][PF(6)] (dppe = Ph(2)PCH(2)CH(2)PPh(2)), [CpIr(MeCN)(3)][PF(6)](2) (Cp = eta(5)-C(5)Me(5)), [CpRu(MeCN)(3)][PF(6)], and [M(CO)(3)(MeCN)(3)] (M = Mo, W) in MeCN or MeCN-THF at room temperature afforded either the doubly bridged complexes [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)M(PPh(3))] (M = Pt (3), Pd (4)), [(Me(2)Tp)W(=S)(micro-S)(2)M(cod)] (M = Ir, Rh (7)), [(Me(2)Tp)W(=S)(micro-S)(2)Rh(dppe)], [(Me(2)Tp)W(=S)(micro-S)(2)RuCp] (10), and [Et(4)N][(Me(2)Tp)W(=S)(micro-S)(2)W(CO)(3)] (12) or the triply bridged complexes including [(Me(2)Tp)W(micro-S)(3)PtMe(3)] (5), [(Me(2)Tp)W(micro-S)(3)IrCp][PF(6)] (9), and [Et(4)N][(Me(2)Tp)W(micro-S)(3)Mo(CO)(3)] (11), depending on the nature of the incorporated metal fragment. The X-ray analyses have been undertaken to clarify the detailed structures of 3-5, 7, and 9-12. 相似文献
7.
Matias L. del Hoyo 《Topology and its Applications》2008,155(11):1189-1200
We present an intrinsic and concrete development of the subdivision of small categories, give some simple examples and derive its fundamental properties. As an application, we deduce an alternative way to compare the homotopy categories of spaces and small categories, by using partially ordered sets. This yields a new conceptual proof to the well-known fact that these two homotopy categories are equivalent. 相似文献
8.
A. Ruiz De la Cruz A. Ferrer J. del Hoyo J. Siegel J. Solis 《Applied Physics A: Materials Science & Processing》2011,104(2):687-693
In this work, we report a model for accurately calculating the focal volumes corresponding to astigmatic elliptical beams
used in fs-laser waveguide writing. The model is based on the use of the ABCD matrix formalism for the propagation of a Gaussian beam. The code includes the effects of propagation on the astigmatic elliptical
beam, and the effects of beam truncation and diffraction at the entrance pupil of the focusing objective due to beam clipping
when overfilling the pupil. The results predict that for a given astigmatism value and propagation distance it is possible
to efficiently suppress the astigmatic focus closer to the surface. This explains previous experimental results where single
structure waveguides with controllable aspect-ratio were fabricated using astigmatic-elliptical beams. Furthermore, we investigate
the respective roles of astigmatism and beam propagation, as well as the strong impact of truncation and diffraction effects
caused by clipping the beam at the pupil of the focusing optics. Finally, based on the results from our model, we present
some practical considerations in terms of beam propagation and phase wrapping constraints. 相似文献
9.
A global action is the algebraic analogue of a topological manifold. This construction was introduced in first place by A.
Bak as a combinatorial approach to K-Theory and the concept was later generalized by Bak, Brown, Minian and Porter to the
notion of groupoid atlas. In this paper we define and investigate homotopy invariants of global actions and groupoid atlases,
such as the strong fundamental groupoid, the weak and strong nerves, classifying spaces and homology groups. We relate all
these new invariants to classical constructions in topological spaces, simplicial complexes and simplicial sets. This way
we obtain new combinatorial formulations of classical and non classical results in terms of groupoid atlases.
相似文献
10.
PERT and CPM are two valuable tools for the planning, scheduling and controllingof projects, but they do not on their own deal with the interdependence between planning resource utilization or direct cost expenditure and sclheduling with its overhead cost (penalty cost and/or reward bonus) implications. Several approaches to overcome this deficiency are possible, this paper dealing with one known as Decision CPM. The most recent approach to the Decision CPM problem known to the authors leads to relatively large integer programming problems which are solved as such. This paper considers a restricted formulation of the Decision CPM problem in an integer programming framework, and shows how it may be solved relatively easily witlhout resort to integer programming methods. Extensions of the restricted model are also considered briefly, some of which pose no difficulties, while others suggest the need for a hybrid of other approaches and that described here. 相似文献