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71.
R. Cristescu A. Doraiswamy S. Grigorescu D. Mihaiescu R.J. Narayan I.N. Mihailescu D.B. Chrisey 《Applied Surface Science》2007,253(15):6476-6479
We report the successful deposition of polycaprolactone polymer by MAPLE using a KrF* excimer laser (λ = 248 nm, τ = 7 ns). According to FTIR spectra the deposited films have similar chemical structure to the dropcast material. The fluence plays a key role in optimizing the performances of MAPLE-synthesized polycaprolactone structures. We demonstrated that MAPLE allows for controlling the morphology of films to the level required in targeted drug delivery of pharmacologic agents. 相似文献
72.
Abstract1-Tributylstannyl glycals were applied as versatile tools in the Pd(0)-mediated synthesis of glycal phthalonitrile conjugates. Likewise, selective homo-coupling of 1-tributylstannyl glycals furnishing C1-C1’ linked glycal dimers was investigated by using Pd(II)-species. For both Stille type couplings the rate-accelerating effect of copper(I) thiophene-2-carboxylate (CuTC) was exploited. The synthesis of stannylated glycal precursors was significantly improved by establishing a one-pot two-step procedure via glycosyl sulfoxides. 相似文献
73.
Starting from gypsum, a by-product of lactic acid fabrication process, novel “green” composites have been produced by melt-blending polylactide (PLA) and this filler after a previous specific dehydration to obtain anhydrite II (AII). Such a material is potentially interesting in biodegradable/rigid packaging and in technical applications requiring rigidity, heat resistance and dimensional stability. In order to obtain PLA-AII composites characterized by specific end-use flame retardant properties, the addition of selected organo-modified layered silicates (OMLS) was considered. Co-addition of AII and OMLS leads to PLA (nano)composites characterized by good (nano)filler dispersion, thermal stability and adequate mechanical resistance. The flame retardant properties as shown by cone calorimetry showed significant increase in the ignition time compared to neat PLA and a substantial decrease, i.e., ca. 40%, of the maximum rate of heat release, whereas the UL94 HB test was successfully passed revealing non-dripping effect and extensive char formation. The study represents a new approach in formulating novel PLA grades with improved characteristic features. 相似文献
74.
A non square matrix with coefficients in K[z] can (if a condition on its minors is satisfied) be embedded into a square matrix with determinant 1. Finding theoretically and in an algorithmic way an embedding of small degree is solved by a construction with vector bundles on the projective line over K. 相似文献
75.
A tractor-trailer problem, with full load, from the class of combined routeing and scheduling problems is described. Distinctive features of the problem are: movements must be carried out within certain time windows; subsets of movements are linked in the sense that they must be executed in a certain order; and different priorities are attached to different movements. A new bidirectional sequential constructive heuristic is developed for the solution of this problem. The method constructs routes and schedules for the available tractor fleet. The algorithm attempts to minimize the total time for all the movements by minimizing the time taken up by unproductive movements (so-called deadhead) and waiting time between movements. Some practical aspects of the implementation of the approach are discussed. 相似文献
76.
Marius Buliga 《Linear algebra and its applications》2008,429(7):1528-1545
The resemblance between the Horn-Thompson theorem and a recent theorem by Dacorogna-Marcellini-Tanteri indicates that Schur-convexity and the majorization relation are relevant for applications in the calculus of variations and its related notions of convexity, such as rank one convexity or quasiconvexity. In Theorem 6.6, we give simple necessary and sufficient conditions for an isotropic objective function to be rank one convex on the set of matrices with positive determinant.Majorization is used in order to give a very short proof of a theorem of Thompson and Freede [R.C. Thompson, L.J. Freede, Eigenvalues of sums of Hermitian matrices III, J. Res. Nat. Bur. Standards B 75B (1971) 115-120], Ball [J.M. Ball, Constitutive inequalities and existence theorems in nonlinear elastostatics, in: R.J. Knops (Ed.), Nonlinear Analysis and Mechanics: Heriot-Watt Symposium, vol. 1, Res. Notes Math., 17, Pitman, 1977, pp. 187-241], or Le Dret [H. Le Dret, Sur les fonctions de matrices convexes et isotropes, CR Acad. Sci. Paris, Série I 310 (1990) 617-620], concerning the convexity of a class of isotropic functions which appear in nonlinear elasticity.Next we prove (Theorem 7.3) a lower semicontinuity result for functionals with the form ∫Ωw(D?(x))dx, with w(F)=h(lnVF). Here F=RFUF=VFRF is the usual polar decomposition of F∈gl(n,R), and lnVF is Hencky’s logarithmic strain.We close this paper with a compact proof of Dacorogna-Marcellini-Tanteri theorem, based only on classical results about majorization. The mentioned resemblance of this theorem with the Horn-Thompson theorem is thus explained. 相似文献
77.
78.
In this paper, we consider the global wellposedness of the 3-D incompressible anisotropic Navier-Stokes equations with initial
data in the critical Besov-Sobolev type spaces B{\mathcal{B}} and
B-\frac12,\frac124{\mathcal{B}^{-\frac12,\frac12}_4} (see Definitions 1.1 and 1.2 below). In particular, we proved that there exists a positive constant C such that (ANS
ν
) has a unique global solution with initial data u0 = (u0h, u03){u_0 = (u_0^h, u_0^3)} which satisfies
||u0h||B exp(\fracCn4 ||u03||B4) £ c0n{\|u_0^h\|_{\mathcal{B}} \exp\bigl(\frac{C}{\nu^4} \|u_0^3\|_{\mathcal{B}}^4\bigr) \leq c_0\nu} or
||u0h||B-\frac12,\frac124 exp(\fracCn4 ||u03||B-\frac12,\frac1244) £ c0n{\|u_0^h\|_{\mathcal{B}^{-\frac12,\frac12}_{4}} \exp \bigl(\frac{C}{\nu^4} \|u_0^3\|_{\mathcal{B}^{-\frac12,\frac12}_{4}}^4\bigr)\leq c_0\nu} for some c
0 sufficiently small. To overcome the difficulty that Gronwall’s inequality can not be applied in the framework of Chemin-Lerner
type spaces, [(Lpt)\tilde](B){\widetilde{L^p_t}(\mathcal{B})}, we introduced here sort of weighted Chemin-Lerner type spaces, [(L2t, f)\tilde](B){\widetilde{L^2_{t, f}}(\mathcal{B})} for some apropriate L
1 function f(t). 相似文献
79.
80.
A. SzekeresZs. Fogarassy P. PetrikE. Vlaikova A. CzirakiG. Socol C. RistoscuS. Grigorescu I.N. Mihailescu 《Applied Surface Science》2011,257(12):5370-5374
We obtained AlN thin films by pulsed laser deposition (PLD) from a polycrystalline AlN target using a pulsed KrF* excimer laser source (248 nm, 25 ns, intensity of ∼4 × 108 W/cm2, repetition rate 3 Hz, 10 J/cm2 laser fluence). The target-Si substrate distance was 5 cm. Films were grown either in vacuum (10−4 Pa residual pressure) or in nitrogen at a dynamic pressure of 0.1 and 10 Pa, using a total of 20,000 subsequent pulses. The films structure was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and spectral ellipsometry (SE). Our TEM and XRD studies showed a strong dependence of the film structure on the nitrogen content in the ambient gas. The films deposited in vacuum exhibited a high quality polycrystalline structure with a hexagonal phase. The crystallite growth proceeds along the c-axis, perpendicular to the substrate surface, resulting in a columnar and strongly textured structure. The films grown at low nitrogen pressure (0.1 Pa) were amorphous as seen by TEM and XRD, but SE data analysis revealed ∼1.7 vol.% crystallites embedded in the amorphous AlN matrix. Increasing the nitrogen pressure to 10 Pa promotes the formation of cubic (≤10 nm) crystallites as seen by TEM but their density was still low to be detected by XRD. SE data analysis confirmed the results obtained from the TEM and XRD observations. 相似文献