Parallel Breakup of Polymer Drops under Simple Shear

The deformation and breakup of a single polycarbonate drop in a polyethylene matrix is studied at high temperatures under simple shear flow using a transparent Couette device. We observed “parallel breakup” where the drop breaks after being stretched into a thin sheet parallel to the flow. The breakup occurs at a viscosity ratio greater than 3.5. Deborah number and a stress ratio incorporating elastic moduli can characterize the “parallel breakup”.

Deformation and breakup of a polycarbonate drop in a polyethylene matrix.     

Two new alkaloids and a new polyphenolic compound from <Emphasis Type="Italic">Cotula coronopifolia</Emphasis>

Two new alkaloid derivatives of the 3-benzazocine skeleton (cotuzine A and B) and a new polyphenolic substance (3-(1,3-dihydroxyprop-2-yl)-4-hydroxyanisol) (corimen) have been isolated from the aerial part (stems, leaves) of the plant Cotula coronopifolia (L.). These three new structures were established by spectroscopic procedures (¹H, ¹³C, one- and two-dimensional NMR). The stereochemistry of the new alkaloids was established based on different NOE effects revealed on the NOESY spectrum. Mass spectrometry and IR spectroscopy were used to confirm these structures.     

On the dimensions of species participating in the growth of ammonium oxalate monohydrate crystals from viscosity data of concentrated aqueous solutions

The experimental data of the temperature and concentration dependence of viscosity of concentrated aqueous ammonium oxalate solutions are analysed using the hole theory of liquids and Einstein's model of viscosity. Analysis of the data revealed that the dimensions of the species participating in the growth of ammonium oxalate monohydrate crystals are 3‐5 times larger than the dimensions of individual NH₄⁺ and C₂O₄^2‐ ions composing them. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Electronic Conductive Microporous Polymer‐Based Structures

Summary: This study aims at developing a highly electronic conductive microporous structure from thermoplastic polymers filled with carbon black (CB) and graphite (GR). The matrix was a low viscosity poly(propylene) (PP) and the conductive additives were composed of high specific surface area CB and synthetic flake GR. Conductive blends were first developed using a corotating twin‐screw extruder. Rheological properties and conductivities of these blends were then characterized as a function of blend composition. Blends that show the best compromise between electronic conductivity and processability were subsequently extruded through a sheet die to obtain films of around 500 µm in thickness. These films were then stretched in two successive steps under controlled temperature and stretching rate to generate a film of controlled microporous structure.

TEM of film made from a 50 wt.‐% PP/25 wt.‐% CB/25 wt.‐% GR blend after stretching.     

Spin-coating deposition of PbS and CdS thin films for solar cell application

In this work, we describe a simple spin-coating deposition technique for lead sulphide (PbS) and cadmium sulphide (CdS) films from a methanolic metal–thiourea complex. The characterization of the films by X-ray diffraction and X-ray photoelectron spectroscopy techniques revealed that pure cubic phase PbS and CdS layers were formed via this method. As shown by atomic force microscopy and scanning electron microscopy results, both films were homogeneous and presented a smooth surface. Optical properties showed that the energy band gap of PbS and CdS films were around 1.65 and 2.5 eV, respectively. The PbS film is p-type in nature with an electrical conductivity of around 0.8 S/cm. The hole concentration and mobility were 2.35 × 10¹⁸ cm^?3 and 2.16 × 10^?3 cm²/V/s, respectively, as determined from Hall measurement. Both films were used to develop a thin film solar cell device of graphite/PbS/CdS/ITO/glass. Device characterization showed the power conversion efficiency of around 0.24 %. The corresponding open circuit voltage, short circuit current and fill factor were 0.570 V, 1.32 mA/cm² and 0.32, respectively.     

Mutagenic, antimutagenic and antioxidant activities of a new polyphenolic and a flavonoid substances isolated from Anagallis monelli

A new polyphenolic natural substance: 2,5-dihydroxy-benzoic acid 3'-formyl-5'-hydroxy-phenyl ester (1), Anamighrinal and 3-(O-alpha-L-rhamnosyl) quercetin (2) have been isolated from the methanolic aerial part extract of the plant Anagallis monelli by chromatographic separation. Their structures have been deduced essentially by one and two NMR spectroscopic procedures and mass spectrometry. Antioxidant, mutagenic, antimutagenic activities, of the natural products were realised and positive results were recorded.     

Nauplathizine, a new unusual O-heteroside from Nauplius aquaticus (L)

A novel O-heteroside, (3RS,4RS)-3,4-dihydroxy-4-(2-hydroxy-5-acetylphenyl)-2-[(beta-O-glucopyranosyl)methyl]-but-1-ene (1), named nauplathizine, and a previously known compound, acetophenone-4-O-glucoside (2), were isolated from the antibacterial acetone extract of the aerial parts of Nauplius aquaticus (L) (Asteraceae, Inulae). The structure of 1 was established via its acetylated derivative by means of spectroscopic and chemical data.     

A new biflavonoid and an isobiflavonoid from Rhus tripartitum

A new biflavonoid masazinoflavanone (1) and the isobiflavonoid calodenone (2) have been isolated and characterized from the methanolic aerial part extract of the plant Rhus tripartitum. Their structures have been deduced from extensive spectral analysis (NMR and MS). Interpretation of the nuclear overhauser effects (NOESY) permitted us to establish relative stereochemistry of these natural products.     

Antimicrobial and antioxidant activities of Artemisia herba-alba essential oil cultivated in Tunisian arid zone

This study was conceived to examine the antimicrobial and antioxidant activities of four essential oil types extracted by hydrodistillation from the aerial parts of Artemisia herba-alba cultivated in southern Tunisia. The chemical composition was investigated using both capillary GC and GC/MS techniques. β-thujone, α-thujone, α-thujone/β-thujone and 1,8-cineole/camphor/α-thujone/β-thujone were respectively, the major components of these oil types. The antimicrobial activity of different oils was tested using the diffusion method and by determining the inhibition zone. The results showed that all examined oil types had great potential of antimicrobial activity against strains. In addition, antioxidant capacity was assessed by different in vitro tests and weak activity was found for these A. herba-alba oils.     

Antibacterial, antifungal and cytotoxic activities of two flavonoids from Retama raetam flowers

We have investigated the antibacterial, antifungal and cytotoxic activities of two flavonoids isolated from Retama raetam flowers using the disc diffusion and micro-dilution broth methods. The cytotoxic activity was tested against Hep-2 cells using the MTT assay. The compounds licoflavone C (1) and derrone (2) were active against Pseudomonas aeruginosa and Escherichia coli (7.81-15.62 μg/mL) and showed important antifungal activity. Strong antifungal activity against Candida species (7.81 μg/mL) was for example found with compound 2. The tested compounds also showed strong cytotoxicity against Hep-2 cells. These two compounds may be interesting antimicrobial agents to be used against infectious diseases caused by many pathogens.