Gold-surface binding of molecular switches studied by M?ssbauer spectroscopy

The nonanuclear coordination compound [Mo^IV{(CN)Fe^III(3-methyl-saldptn)}₈]Cl₄ exhibits multiple spin transitions (3-methyl-saldptn = N,N′-bis(3′′-methyl-2′′-hydroxy-benzyliden)-1,7-diamino-4-azaheptane). This spin crossover cluster is bound via a self-assembled monolayer onto a two dimensional array gold surface. M?ssbauer spectroscopy indicates that the thermally and optically induced spin crossover of the compound is maintained. Thereby, the foundation for its potential practical application (e.g. in the field of information storage) was laid.     

KCo(H2O)2BP2O8·0.48H2O and K0.17Ca0.42Co(H2O)2BP2O8·H2O: two cobalt borophosphates with helical ribbons and disordered (K,Ca)/H2O schemes

The two title compounds, potassium diaquacobalt(II) borodiphosphate 0.48‐hydrate and potassium–calcium(0.172/0.418) diaquacobalt(II) borodiphosphate monohydrate, were synthesized hydrothermally. They are new members of the borophosphate family characterized by _∞[BP₂O₈]³⁻ helices running along [001] and constructed of boron (Wyckoff position 6b, twofold axis) and phosphorus tetrahedra. The [CoBP₂O₈]⁻ anionic frameworks in the two materials are structurally similar and result from a connection in the ab plane between the CoO₄(H₂O)₂ coordination octahedra (6b position) and the helical ribbons. Nevertheless, the two structures differ in the disorder schemes of the K,Ca and H₂O species. The alkali cations in the structure of the pure potassium compound are disordered over three independent positions, one of them located on a 6b site. Its framework is characterized by double occupation of the tunnels by water molecules located on twofold rotation axes (6b) and a fraction of alkali cations; its cell parameters, compared with those for the mixed K,Ca compound, show abnormal changes, presumably due to the disorder. For the K,Ca compound, the K and Ca cations are on twofold axes (6b) and the channels are occupied only by disordered solvent water molecules. This shows that it is possible, due to the flexibility of the helices, to replace the alkali and alkaline earth cations while retaining the crystal framework.     

A Convenient Laboratory Preparation of N,N-Dimethyl-dichloro-methylene-iminium Chloride (Phosgene-iminium chloride)

A method of preparation of the title compound 1a avoiding the use of gaseous chlorine is described. Tetramethylthiuram disulfide 4 is oxidized with sulfuryl chloride to dime thyl thiocarbamoyl chloride 5, which is converted to 1a by means of phosphorus pentachloride.     

Antimicrobial and Antioxidant Properties of Total Polyphenols of Anchusa italica Retz

Anchusa italica Retz has been used for a long time in phytotherapy. The aim of the present study was to determine the antioxidant and antibacterial activities of extracts from the leaves and roots of Anchusa italica Retz. We first determined the content of phenolic compounds and flavonoids using Folin–Ciocalteu reagents and aluminum chloride (AlCl₃). The antioxidant activity was determined using three methods: reducing power (FRAP), 2.2-diphenyl-1-picrylhydrazyl (DPPH), total antioxidant capacity (TAC). The antimicrobial activity was investigated against four strains of Escherichia coli, two strains of Klebsiella pneumoniae and coagulase-negative Staphylococcus, and one fungal strain of Candida albicans. The results showed that the root extract was rich in polyphenols (43.29 mg GAE/g extract), while the leave extract was rich in flavonoids (28.88 mg QE/g extract). The FRAP assay showed a strong iron reduction capacity for the root extract (IC₅₀ of 0.11 µg/mL) in comparison to ascorbic acid (IC₅₀ of 0.121 µg/mL). The DPPH test determined an IC₅₀ of 0.11 µg/mL for the root extract and an IC₅₀ of 0.14 µg/mL for the leaf extract. These values are low compared to those for ascorbic acid (IC₅₀ of 0.16 µg/mL) and BHT (IC₅₀ 0.20 µg/mL). The TAC values of the leaf and root extracts were 0.51 and 0.98 mg AAE/g extract, respectively. In vitro, the extract showed inhibitory activity against all strains studied, with diameters of zones of inhibition in the range of 11.00–16.00 mm for the root extract and 11.67–14.33 mm for the leaf extract. The minimum inhibitory concentration was recorded for the leaf extract against E. coli (ATB:57), corresponding to 5 mg/mL. Overall, this research indicates that the extracts of Anchusa italica Retz roots and leaves exert significant antioxidant and antibacterial activities, probably because of the high content of flavonoids and polyphenols.     

Callosal connections of dorsal versus ventral premotor areas in the macaque monkey: a multiple retrograde tracing study

Background  

The lateral premotor cortex plays a crucial role in visually guided limb movements. It is divided into two main regions, the dorsal (PMd) and ventral (PMv) areas, which are in turn subdivided into functionally and anatomically distinct rostral (PMd-r and PMv-r) and caudal (PMd-c and PMv-c) sub-regions. We analyzed the callosal inputs to these premotor subdivisions following 23 injections of retrograde tracers in eight macaque monkeys. In each monkey, 2–4 distinct tracers were injected in different areas allowing direct comparisons of callosal connectivity in the same brain.     

Elements with generalized bounded conjugation orbits

For a pair of linear bounded operators and on a complex Banach space , if commutes with then the orbits of under are uniformly bounded. The study of the converse implication was started in the 1970s by J. A. Deddens. In this paper, we present a new approach to this type of question using two localization theorems; one is an operator version of a theorem of tauberian type given by Katznelson-Tzafriri and the second one is on power-bounded operators by Gelfand-Hille. This improves former results of Deddens-Stampfli-Williams.     

Stationary problem of third-grade fluids in two and three dimensions: existence and uniqueness

This paper is devoted to the stationary problem of third-grade fluids in two and three dimensions. In two dimensions, we show existence of solutions and uniqueness, for a boundary of class C^2,1 and small data, by generalizing the method used by J.M. Bernard for the stationary problem of second-grade fluids (we deal with a polynomial of four degrees instead of two degrees). Contrary to the case of two dimensions, the resolution of the problem of third-grade fluids in three dimensions requires the physical condition |α₁+α₂|<(24νβ)^1/2. From this condition, we derive two “pseudo ellipticities” for the operator ν|A(u)|²+(α₁+α₂)tr(A(u)³)+β|A(u)|⁴, where A(u) is a 3-order symmetric matrix such that tr(A(u))=0. Thus, with, in addition, a sharp estimate of the scalar product (|A(u)|²A(u)-|A(v)|²A(v),A(u)-A(v)), we are able to prove existence of solutions and uniqueness, for a boundary of class C^2,1 and small data, in three dimensions.

Résumé

Cet article est consacré au problème stationnaire des fluides de grade trois en dimension deux et trois. En dimension deux, nous montrons l’existence de solutions et l’unicité, pour une frontière de classe C^2,1 et une donnée petite, en généralisant la méthode utilisée par J.M. Bernard pour le problème stationnaire des fluides de grade deux (nous avons affaire à un polynôme de degré quatre au lieu de deux). Contrairement au cas de la dimension deux, la résolution du problème des fluides de grade trois en dimension trois requière la condition physique |α₁+α₂|<(24νβ)^1/2. De cette condition, nous déduisons deux “pseudo matrice” pour l’opérateur ν|A(u)|²+(α₁+α₂)tr(A(u)³)+β|A(u)|⁴, où A(u) est une matice symétrique d’ordre 3 à trace nulle. De là, avec, en plus, une fine estimation du produit scalaire (|A(u)|²A(u)-|A(v)|²A(v),A(u)-A(v)), nous sommes capables de prouver l’existence de solutions et l’unicité, pour une frontière de classe C^2,1 et une donnée petite, en dimension trois.     

ON THE SUPERSTABILITY OF THE PEXIDER TYPE GENERALIZED TRIGONOMETRIC FUNCTIONAL EQUATIONS

The aim of this paper is to investigate the superstability problem for the pexiderized trigonometric functional equation∑ v∈Φ∫Kf(xkv(y)k-1)dwK(k)= Φ g(x)h(y), x, y ∈ G,where G is any topological group, K is a compact subgroup of G, ωK is the normalized Haar measure of K, Φ is a finite group of K-invariant morphisms of G and f, g, h are continuous complex-valued functions.Consequently, we have generalized the results of stability for d'Alembert's and Wilson's equations by R. Badora, J. Baker, B. Bouikhalene, P. Gavruta, S. Kabbaj, Pl. Kannappan, G. H.Kim, J.M. Rassias, A. Roukbi, L. Sz′ekelyhidi, D. Zeglami, etc.