Essential oil analysis and antibacterial activity of Rosmarinus tournefortii from Algeria

The volatile compounds obtained by hydrodistillation of the aerial parts of Rosmarinus tournefortii De Noé. growing wild in the occidental region of Algeria were analyzed by GC/MS. Thirty-six compounds were characterized representing 95.6% of the essential oil, with camphor (37.6%), 1,8-cineole (10.0%), p-cymene-7-ol (7.8%), and borneol (5.4%) as the major components. The antimicrobial activity was evaluated against three pathogenic bacteria: Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus). The minimum inhibitory concentration (MIC; mg/mL) was determined by sub-culture on Muller Hinton agar plates. The essential oil exhibited strong antibacterial activity against E. coli and P. aeruginosa, and was also active against Staphylococcus aureus.     

Public Disclosure Programs vs. traditional approaches for environmental regulation: Green goodwill and the policies of the firm

A Public Disclosure Program (PDP) is compared to a traditional environmental regulation (exemplified by a tax/subsidy) in a simple dynamic framework. A PDP aims at revealing the environmental record of firms to the public. This information affects its image (goodwill or brand equity), and ultimately its profit. A firm polluting less than its prescribed target would win consumer’s sympathy and raise its goodwill, whereas it is the other way around when the firm exceeds its emissions quota. The evolution of this goodwill is assumed to depend also on green activities or advertising expenditures. Within this framework, we analyze how a PDP affects the firm’s optimal policies regarding emissions, pricing and advertising as compared to a traditional regulation. We show that advertising acts as a complementary device to pricing and that emissions are increasing in goodwill. The role of a standard or target level for emissions turns out to be totally different under both policy regimes. In the case of a tax/subsidy approach, this target level only acts as constant who increases or decreases profit by a fixed amount, but it does not affect the policy of the firm. On the contrary, if a PDP is implemented, the target value for emissions enters in an important way in the goodwill accumulation mechanism and determines how the firm reacts to the regulation and what is the time path for the economic and environmental variables. Moreover, this value is also crucial to determine the possibility that a PDP is profit improving. A policy implication of this fact is that regulators should be particularly careful in fixing the emission standard when a PDP is applied. The theoretical results are complemented with a numerical illustration.     

Thermal and FTIR analysis of the miscibility and phase behaviour of poly (isobutyl methacrylate-co-4-vinylpyridine)/poly (styrene-co-acrylic acid) systems

The miscibility and phase behaviour of poly (isobutyl methacrylate-co-4-vinylpyridine) containing 20 mol% of 4-vinylpyridine (IBM4VP20) and poly (styrene-co-acrylic acid) containing 27 or 32 mol% of acrylic acid (SAA27 or SAA32) mixtures were investigated by DSC, TGA and FTIR spectroscopy in the 25–180 °C temperature range. The results showed that sufficient specific carboxyl–pyridine hydrogen bonding interactions occurred between these copolymers and led to miscible blends as cast from THF and to inter-polymer complexes of significantly improved thermal stability when butan-2-one is the common solvent. The self-association effect on the inter-polymer interactions was evidenced by the decrease of complexation yields, observed when the carboxylic content is increased above 27 mol% as with SAA32.The trend of phase behaviour predicted by a thermodynamic analysis of the specific interactions of hydrogen bonding type that occurred between the two components of the SAA27/IBM4VP20 blends, neglecting the weak carboxyl–ester interactions and the functional group accessibility effect, carried out using the Painter–Coleman association model that considers the screening effects, is in a fair agreement with the experimental results. Moreover an LCST is predicted to occur at relatively high temperature.     

Nigericin and grisorixin methyl ester from the Algerian soil-living Streptomyces youssoufiensis SF10 strain: a computational study on their epimeric structures and evaluation of glioblastoma stem cells growth inhibition

The present work describes the metabolites produced by a strain identified as Streptomyces youssoufiensis, whose secondary metabolites profile has not been studied so far. The crude ethyl acetate extract was analyzed by high performance liquid chromatography-electrospray ionization mass spectrometry, leading to the detection of the ionophoric polyethers nigericin, epinigericin, abierixin and the newly isolated grisorixin methyl ester. The presence of epimeric forms of nigericin/epinigericin and grisorixin/epigrisorixin has spurred density functional theory computational calculations. This analysis was able to provide the relative stability of the most favored epimers, setting the basis for general structural considerations applicable to several other polyethers. Both nigericin sodium salt and grisorixin methyl ester showed to affect glioblastoma stem cells proliferation in a dose-dependent manner, with a higher activity for the more lipophilic grisorixin methyl ester (GI₅₀ values of 3.85 and 3.05 μM for VIPI and COMI human glioblastoma stem cells, respectively).     

Cationic Gold(III) Alkyl Complexes: Generation,Trapping, and Insertion of Norbornene

Migratory insertion of alkenes into gold–carbon bonds, a fundamental yet unprecedented organometallic transformation, has been investigated from a discrete (P,C) cyclometalated gold(III) dimethyl complex. Methide abstraction by B(C₆F₅)₃ is shown to generate a highly reactive cationic Au^III complex that evolves spontaneously by C₆F₅ transfer from boron. In the presence of norbornene, migratory insertion into the Au C bond proceeds readily. The resulting norbornyl complex is efficiently trapped with pyridines or chloride to give stable four‐coordinate adducts.     

A crystalline σ complex of copper

Over the last decades, our understanding of σ-bond activation at transition metals has progressed considerably from both fundamental and synthetic points of view thanks to the preparation and characterization of a variety of σ complexes. Here we report the synthesis and structural analysis of the first σ complex involving a coinage metal. The copper(I) complex 2 derived from the diphosphine-disilane [Ph(2)P(C(6)H(4))Me(2)Si-SiMe(2)(C(6)H(4))PPh(2)] (1) has been isolated and crystallographically characterized. The coordination of the Si-Si σ bond to copper was thoroughly analyzed by quantum-chemical methods.     

Synthesis and Properties of Long-Chain Aromatic Telechelic Monodispersed Diols Radical-Initiated,Addition of 2-Mercaptoethanol onto α, ω Nonconjugated Dienes

Abstract

The synthesis of aromatic telechelic mono dispersed diols produced from the radical-initiated addition reaction of a twofold excess of 2-mercaptoethanol onto original α,ω nonconjugated dienes reaction is presented. These novel α,ω nonconjugated dienes were prepared by addition reaction of m-isopropyl α,α′dimethyl benzylisocyanate with mono dispersed telechelic diols obtained by fractionation of oligo(ethylene terephthalate)s. In these cases, the long chain α,ω diols were produced selectively and quantitatively. The products are soluble in most organic solvents in contrast to classical oligo (ethylene terephthlate)s and posses a lower glass transition and melting temperatures.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Figures S1-S3.     

An effective model for Lipschitz wrinkled arches

Within the framework of the Koiter's linear elastic shell theory, we study the limit model of a Lipschitz curved arch whose mid-surface is periodically waved. The magnitude and the period of the wavings are of the same order. To achieve the asymptotic analysis, we consider a mixed formulation, for which we perform a two-scale homogenization technique. We prove the convergence of the displacements, the rotation of the normal, and the membrane strain. From the limit formulation, we derive an effective model for curved critically wrinkled arches. It introduces two membrane strain functions—instead of one in the classical case—and exhibits a corrector membrane term to the coupling between the rotation of the normal and the membrane strain.     

Modeling of fixed-bed adsorption of Cs+ and Sr2+ onto clay–iron oxide composite using artificial neural network and constant–pattern wave approach

A low-cost, non-toxic and effective adsorbent constituted by a montmorillonite coated by iron oxides (montmorillonite–iron oxide composite) was prepared to assess its effectiveness in the removal of Cs⁺ and Sr²⁺ from aqueous solution. Dynamic adsorption experiments were carried out at room temperature under the effect of various operating parameters such as bed depth Z (5–15 cm), initial cation concentration C ₀ (2–50 mg L^?1) and volumetric flow rate Q (0.5–8 mL min^?1). Column performance has been modeled with constant-pattern wave approach combined to the Freundlich isotherm model and artificial neural network (ANN) models. The time, initial cation concentration, bed depth and volumetric flow rate were chosen as the input variables whereas, the outlet concentration C _t was considered as the output variable. The developed network was found to be useful in predicting the breakthrough curves. Experimental data for the used system were well fitted with ANN than the combined constant–pattern wave approach.