Characterization of the coincidence set for mixed signorini problems

For a mixed Signorini problem, reduction to a boundary variational inequality is derived. It is shown that its solution is a function constituted, on one portion of the boundary, of the upper-skirting function of solutions family of some associated linear mixed boundary value problems and, on the other portion, of the lower-skirting function of the same family. Qualitative behavior of the solution on different portions when perturbing the unknown boundary is analyzed. This shows in particular the usefulness of reduction to the boundary in some linear and nonlinear elliptic problems, even when usual variational methods cannot be applied for such purpose.     

Left and right generalized Drazin invertible operators

In this paper, we define and study the left and the right generalized Drazin inverse of bounded operators in a Banach space. We show that the left (resp. the right) generalized Drazin inverse is a sum of a left invertible (resp. a right invertible) operator and a quasi-nilpotent one. In particular, we define the left and the right generalized Drazin spectra of a bounded operator and also show that these sets are compact in the complex plane and invariant under additive commuting quasi-nilpotent perturbations. Furthermore, we prove that a bounded operator is left generalized Drazin invertible if and only if its adjoint is right generalized Drazin invertible. An equivalent definition of the pseudo-Fredholm operators in terms of the left generalized Drazin invertible operators is also given. Our obtained results are used to investigate some relationships between the left and right generalized Drazin spectra and other spectra founded in Fredholm theory.     

Chemical composition and antimicrobial activity of the essential oil of Algerian Phlomis bovei De Noé subsp. bovei

The chemical composition of essential oil obtained by steam distillation of dried aerial parts of Phlomis bovei De Noé subsp. bovei collected from Algeria, was analyzed by GC and GC/MS. Seventy five constituents (corresponding to 86.37% of the total weight) were identified. The main components were: germacrene D, beta-caryophyllene, beta-bournonene, thymol and hexahydrofarnesyl acetone. Furthermore, the antimicrobial activity of the oil was evaluated against six gram (+/-) bacteria and three pathogenic fungi, using the agar dilution technique. It was found that the oil exhibited strong antimicrobial activity against most of the tested microorganisms.     

Chemical Preparation,Spectroscopic Study and Crystal Structure of DL 2-Ammoniumbutyric Dihydrogenmonophosphate ({\rm CH_3CH_2CHCOOH)(H_2PO_4)^{\hbox{\bf --}}}\vspace*{-2pt}\break\hspace*{-26pt}|\hspace*{26pt}\break\hspace*{-24pt}{^{\bm +}}{\rm NH_3}\hspace*{24pt}}

Crystals of DL 2-ammoniumbutyric dihydrogenmonophosphate were obtained by evaporating an aqueous solution containing equimolar quantities of DL 2-amino butyric and orthophosphoric acids. IR and NMR spectrometry studies has been investigated and confirmed by X-ray single crystal diffraction results. The title compound is monoclinic, space group P2 1 /c, unit cell dimensions a = 10.5450(3) Å, b = 10.0486(3) Å, c = 8.9526(4) Å, g = 111.769(5);. Using 1,303 reflections with I > 3 (I) measured on CAD4 Mach 3 diffractometer, the crystal structure was solved by direct methods and was refined by least squares full matrix procedures to R = 0.038. The main feature of this structure consists of an alternate stacking of H 2 PO 4 m tetrahedral sheets and NH 3 C 3 H 6 COOH + cation layers. The H 2 PO 4 m groups are associated to form infinite chains [(H 2 PO 4 )n] n m . The crystal structure is stabilized by a three-dimensional network of strong hydrogen bonds.     

The first barium tin(II) bromide fluoride

In an effort to prepare barium tin(II) bromide fluorides for the first time, possibly similar to the chloride fluorides obtained earlier in our laboratory, precipitation reactions were carried out by mixing aqueous solutions of SnF₂ and of BaBr₂.2H₂O. In contrast with the chloride fluoride system, a single powdered phase was obtained throughout the SnF₂ – BaBr₂ system, with the yield being maximum at X ≈ 0.25, where X is the molar fraction of barium bromide in the reaction mixture. Phase identification with the JCPDS database failed to produce a match, confirming that a new phase had been produced. The exact chemical composition of the new compound has not been obtained yet. Based on the X value for the maximum yield, the Sn/Ba ratio is likely to be 3/1 or 2/1. The Mössbauer spectrum at ambient conditions shows that bonding to tin(II) is covalent, therefore with the tin lone pair being stereoactive. The Mössbauer parameters (δ = 3.68 mm/s, Δ = 0.99 mm/s) are similar to those of SnBrF and of Sn₂BrF₅, thereby showing that tin is bonded to both fluorine and bromine. The larger isomer shift and lower quadrupole splitting than in tin(II) fluorides show that the stereoactivity of the tin lone pair is lower than in the fluorides. The Mössbauer parameters fit well the linear correlation of the quadrupole splitting versus the isomer shift” that has been shown to be present in other series of tin(II) compounds. The linear decrease on this correlation shows that the contribution of non-spherical orbitals (p and d) to the lone pair is a much larger contributor to the quadrupole splitting than lattice distortions. The structure is likely made of Ba²⁺ cations and tin(II) fluoride bromide polyatomic anions, with covalent bonding withinthe anions.     

Trace and essential elements determination in baby formulas milk by INAA and k 0-INAA techniques

As a part of the food analysis program executed at Es-Salam research reactor by neutron activation analysis laboratory, the concentration of As, Ba, Br, Ca, Fe, K, La, Rb and Zn in baby formulas milk have been determined by using INAA and k ₀-NAA techniques. It was found that the concentration of all elements obtained by both techniques was relatively identical for the three brands of the 0–6 and 6–12 months of analyzed samples. In addition, the analytical results have been compared with those given by producers.     

Partial Characterization of Xylanase Produced by Caldicoprobacter algeriensis,a New Thermophilic Anaerobic Bacterium Isolated from an Algerian Hot Spring

To date, xylanases have expanded their use in many processing industries, such as pulp, paper, food, and textile. This study aimed the production and partial characterization of a thermostable xylanase from a novel thermophilic anaerobic bacterium Caldicoprobacter algeriensis strain TH7C1^T isolated from a northeast hot spring in Algeria. The obtained results showed that C. algeriensis xylanase seems not to be correlated with the biomass growth profile whereas the maximum enzyme production (140.0 U/ml) was recorded in stationary phase (18 h). The temperature and pH for optimal activities were 70 °C and 11.0, respectively. The enzyme was found to be stable at 50, 60, 70, and 80 °C, with a half-life of 10, 9, 8, and 4 h, respectively. Influence of metal ions on enzyme activity revealed that Ca⁺² enhances greatly the relative activity to 151.3 %; whereas Hg²⁺ inhibited significantly the enzyme. At the best of our knowledge, this is the first report on the production of xylanase by the thermophilic bacterium C. algeriensis. This thermo- and alkaline-tolerant xylanase could be used in pulp bleaching process.     

A laboratory investigation of noise reduction by riblike structures on the ground

This paper investigates the use of periodically spaced edges or wells for the control of road traffic noise. The wells have uniform height and width and are placed on the ground. Physical scale modeling is used to assess the acoustic performance of these structures under laboratory conditions. It is shown that, in certain situations where the use of conventional barriers would not be appropriate, strategically designed riblike structures can provide insertion losses of typically 10-15 dB. The findings are explained in terms of acoustic scattering with the approaches used in the study of resonators and diffraction/interference gratings.     

Structural and antitumor properties of the YSNSG cyclopeptide derived from tumstatin

We previously demonstrated that the NC1[alpha3(IV)185-191] CNYYSNS peptide inhibited in vivo tumor progression. The YSNS motif formed a beta turn crucial for biological activity. The aim of the present study was to design a YSNSG cyclopeptide with a constrained beta turn on the YSNS residues more stable than CNYYSNS. By nuclear magnetic resonance and molecular modeling, we demonstrated that the YSNSG cyclopeptide actually adopted the expected beta-turn conformation. It promoted melanoma cell adhesion and prevented their adhesion to the native peptide. It inhibited in vitro cell proliferation and migration through Matrigel by downregulating proteolytic cascades. Moreover, intraperitoneal administration of the YSNSG cyclopeptide inhibited melanoma progression far more efficiently than the native peptide. The increased solubility and stability at low pH of the YSNSG cyclopeptide suggest this peptide as a potent antitumor therapeutic agent.