Sorption-desorption behavior of bispyrazolato-copper(II) 1D coordination polymers

A new polycrystalline vapochromic polymorph of the one-dimensional copper bispyrazolate polymer reversibly and selectively absorbs a number of small molecules; the crystal structures of the anhydrous and fully hydrated species, determined by powder diffraction methods, are markedly different despite their simple, fast, and reversible interconversion.     

Bandwidth allocation in ATM networks

In an ATM network, bandwidth is allocated at different levels and in different stages. At the physical level, the ATM topology can be dynamically reconfigured by adding/removing truns between ATM switches. This allocation of bandwidth is made possible by the SONET Synchronous Transfer Mode (STM) infrastructure equipped with Digital Cross Connect Systems (DCSs). We will refer to this allocation asSTM allocation. At the ATM level, we can allocate bandwidth to individual Virtual Circuits (ATM-VC allocation) as well as to Virtual Paths (ATM-VP allocation). For example, in order to implement the Connectionless Network Access layer functions we find it convenient to organize the Virtual Paths in a Connectionless Overlay Network. This introduces another type of bandwidth allocation (CLS allocation). In this paper, we address and formulate the above bandwidth allocation problems, and propose efficient techniques for their solution. We illustrate these techniques with examples based on STM and CLS allocation, respectively.This work was jointly supported by the Brazilian National Science Council (CNPq) and NSF.     

Semilinear equations with exponential nonlinearity and measure data

We study the existence and non-existence of solutions of the problem

(0.1)

where Ω is a bounded domain in , N3, and μ is a Radon measure. We prove that if , then (0.1) has a unique solution. We also show that the constant 4π in this condition cannot be improved.     

Synthesis,structure elucidation and chemotherapeutic activity of 6-substituted 1-ethyl-1,4-dihydro-7-[(1-imidazolyl)phenylmethyl]- 4-oxo-3-quinolinecarboxylic acids

The synthesis, structure elucidation and chemotherapeutic activity of novel 3-quinolinecarboxylic acid derivatives are reported. These derivatives are characterized by a group (1-imidazolyl)phenylmethyl attached to the 7-position and chloro 10a , fluoro 10b or methoxy 10c appended to the 6-position.     

A variant of Poincaré's inequality

We show that if $\text{Ω?}\text{R}{}^{\mathrm{N}}\text{,}\text{N?2}$, is a bounded Lipschitz domain and $\text{(ρ}{}_{\mathrm{n}}\text{)?L}{}^1\text{(}\text{R}{}^{\mathrm{N}}\text{)}$ is a sequence of nonnegative radial functions weakly converging to δ₀ then there exist C>0 and n₀?1 such that

$\text{∫}\text{Ω}\text{f??}\text{∫}\text{Ω}\text{f}{}^{\mathrm{p}}\text{?C}\text{∫}\text{Ω}\text{∫}\text{Ω}\text{|f(x)?f(y)|}{}^{\mathrm{p}}\text{|x?y|}{}^{\mathrm{p}}\text{ρ}{}_{\mathrm{n}}\text{(|x?y|)}\text{d}\text{x}\text{d}\text{y}\text{?f∈L}{}^{\mathrm{p}}\text{(Ω)}\text{?n?n}{}_0\text{.}$

The above estimate was suggested by some recent work of Bourgain, Brezis and Mironescu (in: Optimal Control and Partial Differential Equations, IOS Press, 2001, pp. 439–455). As n→∞ in (1) we recover Poincaré's inequality. We also extend a compactness result of Bourgain, Brezis and Mironescu. To cite this article: A.C. Ponce, C. R. Acad. Sci. Paris, Ser. I 337 (2003).     

Mathematical Foundation of Kapitsa's Hypothesis About the Origin and Structure of Ball Lightning

This paper is devoted to the mathematical rationale of the Kapitsa's hypothesis about interference nature of the phenomenon known as ball lightning. It is shown that (i) there are exact solutions of the free Maxwell equations in vacuum describing closed spherical magnetic surfaces (with a tangential time dependent magnetic field, and without an electric field) and (ii) ring-like formations with tangential time-dependent electric field (and with a zero magnetic field everywhere on the ring). It is concluded that the form of these spheres and rings does not suffer changes with time.     

The P\bar 1 space group changes in journal of crystallographic and spectroscopic research and in journal of chemical crystallography

The crystal structures of seven compounds, originally described in the centrosymmetric triclinic space group (No. 2), have been revised to centered monoclinic. Six are now described in space group No. 15 (C2/c or I2/a) and one in space group No. 12 (C2/m). Three structures (TADTEX, VICHIY, YAWZUR) have been re-refined in the correct space group. For six instances the decrease in symmetry results in only minor adjustments and the structure is essentially correct as it is expected when the original and the revised space groups are both centrosymmetric. However, in one instance (VICHIY) the reformulation in the higher space group changes (unexpectedly) the molecular dimension as much as 0.12 Å, even if the space group change is between two centrosymmetric space groups (from to C2/c). This was attributed to the easy decomposition of the crystal. The percentage of revised crystal structures was found to be 1.71%, namely 8 on a total of 467 analyzed structures. A low value if compared to the 3% value found by Marsh and Spek for C2 space group.     

The Reaction of Alkenes with Triangulo-Clusters [Pt3(μ-CO)3(PR3)3]

The reactions of the cluster complexes [Pt₃(-CO)₃L₃], where L=PPh₃ 1a, PPh₂Bz 1b and PCy₃ 1c, with activated mono-olefins have been studied under preparative and equilibrium conditions. At low temperature the olefins react quantitatively giving the adducts [Pt₃(-CO)₃L₃(olefin)] (olefin=trans-dicyanoethene, DCE 2a–2c, maleic anhydride, MA 3a–3c). The stereo-chemistry of these unstable clusters has been deduced from low temperature ³¹P, ¹³C, ¹⁹⁵Pt-NMR and I.R. spectra. At higher temperature these adducts in presence of excess of olefin convert quantitatively to stable mononuclear Pt(0) complexes [Pt(CO)L(olefin)] (olefin=DCE 4a–4c, MA 5a–5c, maleimide, MI 6a–6c and 1–4-naphthoquinone, NQ 7a, 7c).     

A free boundary problem of biological interest

During fertilization of certain echinoderms, a long actin-filled tube is extended by the sperm towards the interior of the egg. This yields a parabolic free boundary problem, which differs from the classical one-phase Stefan problem by the presence of a convective term in the partial differential equation, and because the equilibrium interface condition θ(s(t),t) = 0 is here replaced by a kinetic law s′(t) = vθ(s(t),t). This problem is set in variational form and the existence of a solution is proved by means of a Faedo–Galerkin approximation procedure.