G. Popa

Synthesis and Biological Evaluation of New 2-Azetidinones with Sulfonamide Structures

New series of N-(arylidene)hydrazinoacetyl sulfonamides 4a1–6, 4b1–6 and N-(4-aryl-3-chloro-2-oxoazetidin-1-yl)aminoacetyl sulfonamides 5a1–6, 5b1–6 were synthesized. The structures of the new derivatives was confirmed using spectral methods (FT-IR, 1H-NMR, 13C-NMR). The antibacterial activities of these compounds against Gram positive (Staphyloccoccus aureus ATCC 6583, Staphyloccoccus epidermidis ATCC 12228, Enterococcus faecalis ATCC 25912) and Gram negative (Klebsiella pneumoniae CIP 53153, Proteus vulgaris CIP 104989, Citrobacter freundii CIP 5732, Enterobacter cloacae CIP 103475, Escherichia coli ATCC 25922, Pseudomonas aeruginosa CIP 82118) bacterial strains were evaluated using the broth micro-dilution method. Compound 4a2 displayed the highest antibacterial activity, especially against Staphyloccoccus epidermidis, Enterococcus faecalis and Pseudomonas aeruginosa. The antioxidant potential of the synthesized compounds was also investigated according to ferric reducing power, total antioxidant activity and DPPH radical scavenging assays. All tested compounds showed excellent antioxidant activity in comparison with sulfadiazine and sulfisoxazole which were used as parent sulfonamides. Moreover, some of them showed an antioxidant activity comparable with that of ascorbic acid. In general, the compounds designed based on a sulfadiazine skeleton (compounds 4a1–6, 5a1–6) are more active than those obtained from sulfisoxazole (compounds 4b1–6, 5b1–6), and the N-(arylidene)hydrazinoacetyl sulfonamide derivatives 4a1–6, 4b1–6 are more active than their azetidionone analogues 5a1–6, 5b1–6.

Modification of Polymer Blends Properties by Plasma/Electron Beam Treatment. I. Plasma Diagnosis and Bulk Properties of Plasma Treated Blends

Films of isotactic polypropylene/epoxy modified lignin have been plasma and electron beam treated, in order to improve the surface properties and their response to environmental factors. The optimal conditions for the treatment have been established by a detailed plasma diagnosis. The effect of the treatment on the films has been followed by: IR-spectroscopy, X-ray diffraction and differential scanning calorimetry. All results have been comparatively discussed with those corresponding to the untreated samples. It has been established that plasma and electron beam treatments are very efficient in imparting a high polarity and an increased hydrophylicity to the polyolefin-based blends.

Poly(Ethylene Terephthalate) Films with Different Content of Acid-Base Functionalities. I. Surface Modifications

Abstract Treatments of PET in an ion beam-low density plasma system, in oxygen, have been realised. Low energy (100–500 eV), but relatively high does (3.0.1015–9.0.1016 ions/cm2) for ions were used. In this first part, the surface modifications of PET films (investigated by IR spectroscopy, X-ray diffraction, contact angle measurements, XPS angle resolved) are presented. Both chemical and physico-structural modifications take place simultaneous during ion beam treatments. The initial polar group content, immediately after the treatment, but more than this the physico-structural modifications like cross-linking and a restructured crystalline content determine the dynamic effects which control the ageing mechanisms.

Poly (Ethylene Terephthalate) Films with Different Content of Acid-Base Functionalities. II. Gas Phase Analysis and Proposed Mechanisms

Abstract The data about the plasma gas phase analysis and also a contribution to the mechanisms involved in such modifications are presented in this second part. Main 16 neutral species and their evolution in time, with and without PET sample in the treatment system, were investigated by MS. The fluences of atomic and molecular oxygen ions at the polymer surface were determined. A decreased content in neutral species higher is the ion energy is stood out when the PET sample is inside the treatment system. Appreciable differences between the treatments made in saturation regime and those in reimplantation regime were stood out. An enhanced etching mechanism is active in the treatments with ions of 100 and 300 eV, at the lowest dose, while an etching mechanism in stationary regime in a competition with a cross-linking process are important for the treatment with of 500 eV, the same dose. Treatments at this dose do not confer a prevalent acidic or basic character of the PET surface. A diminished etching proc...

Atomic mixing and erosion model applied to polymers

Abstract The reliability of a mathematical model for atomic mixing and erosion in case of poly(ethylene terephthalate) (PET) films treated with 300 eV oxygen ions, at different fluences, was tested using a linear regression program. Statistical results were compared with a proposed etching mechanism on the basis of XPS data. The mathematical model can be applied to the PET samples for which an etching process in stationary regime takes place.