Dual antibacterial effect of immobilized quaternary ammonium and aliphatic groups on PVC

A coating comprising quaternary ammonium salts (QAS) and aliphatic moieties was formed on the poly(vinyl chloride) (PVC) surface in order to confer antibacterial activity. This was achieved by grafting mercaptopropyltrimethoxysilane onto PVC, followed by aminopropyltriethoxysilane. Betaine and dodecenyl succinic anhydride (DDSA) were bonded to free amine groups. The modified PVC samples were characterized by FT-IR, showing that the PVC surface was successfully coated. Energy dispersive X-ray spectroscopy showed the spatial distributions of the elements Si and S, indicating that the coatings were homogeneous. Betaine and DDSA coated PVC showed a better antibacterial performance than the controls. This antibacterial effect was extremely reinforced in betaine-DDSA modified PVC showing greater antibacterial activity than both treatments separately applied. Antibacterial activity against Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis was studied in the treated samples showing that the coating was effective against Gram positive and Gram negative species.Fil: Villanueva, María Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Salinas, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: González, Joaquín Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; ArgentinaFil: Teves, Sergio. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Copello, Guillermo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Metabolismo del Fármaco. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Química y Metabolismo del Fármaco; Argentin

A Theoretical Study on the Vibrational Spectra of PAH Molecules with Aliphatic Sidegroups

The role of aliphatic side groups on the formation of astronomical unidentified infrared emission (UIE) features is investigated by applying the density functional theory (DFT) to a series of molecules with mixed aliphatic-aromatic structures. The effects of introducing various aliphatic groups to a fixed polycyclic aromatic hydrocarbon (PAH) core (ovalene) are studied. Simulated spectra for each molecule are produced by applying a Drude profile at $T$=500 K while the molecule is kept at its electronic ground state. The vibrational normal modes are classified using a semi-quantitative method. This allows us to separate the aromatic and aliphatic vibrations and therefore provide clues to what types of vibrations are responsible for the emissions bands at different wavelengths. We find that many of the UIE bands are not pure aromatic vibrational bands but may represent coupled vibrational modes. The effects of aliphatic groups on the formation of the 8 $\mu$m plateau are qua ntitatively determined. The vibrational motions of methyl ($-$CH$_3$) and methyl ene ($-$CH$_2-$) groups can cause the merging of the vibrational bands of the pa rent PAH and the forming of broad features. These results suggest that aliphatic structures can play an important role in th e UIE phenomenon.Comment: 29 pages, 13 figures, Accepted for publication in Ap

Unidentified Infrared Emission bands: PAHs or MAONs?

We suggest that the carrier of the unidentified infrared emission (UIE) bands is an amorphous carbonaceous solid with mixed aromatic/aliphatic structures, rather than free-flying polycyclic aromatic hydrocarbon (PAH) molecules. Through spectral fittings of the astronomical spectra of the UIE bands, we show that a significant amount of the energy is emitted by the aliphatic component, implying that aliphatic groups are an essential part of the chemical structure. Arguments in favor of an amorphous, solid-state structure rather than a gas-phase molecule as a carrier of the UIE are also presented.Comment: 9 figures, accepted for publication in The Astrophysical Journa

High-molecular weight compounds of nitrogen and sulfur as therapeutic agents

General reviews of the chemotherapy of malaria and tuberculosis have been made;A survey of the physiological properties and therapeutic uses of compounds containing high-molecular weight aliphatic groups has been given;The large amount of lipoidal tissue present in certain strains of bacteria, such as the tubercle bacillus, suggested that the introduction into potential physiologically-active structures of groups which would be lipoidal-soluble might give rise to valuable medicinals. This thought initiated the study and preparation of nitrogen and sulfur compounds containing high-molecular weight aliphatic groups as therapeutic agents;Several nitrogen derivatives have been made for therapeutic testing, These agents include dibutylalkylamines derivatives of tetradecylamine and hexadecylamine. Rearrangement has been shown to occur during the reaction between alpha-halogenonaphthalenes and lithium dialkylamides, beta-dialkylaminonaphthalenes being formed;Several sulfur derivatives containing high-molecular weight aliphatic groups have been prepared for pharmacological testing. These compounds include quinolyl dodecyl sulfides, hydroxy sulfides, imidosulfides and sulfur-containing mercurials;The reaction between laurophenone and phosphorus pentachloride has been shown to give 1-phenyl-1-chlorododeceno-1 in good yield;Several miscellaneous compounds have been prepared for physiological testing. These compounds include anils derived from 1-diethylamino-4-aminopentane, substituted cinchoninic acids and phenothiazine derivatives;Complete pharmacological results are not available, but none of the commands on which reports have been received has shown any significant therapeutic activity

Polyimides with improved compression moldability

The semicrystalline polyimide prepared by reaction of 3,3',4,4' benzophenonetetracarboxylic (BTDA) and 1,3-bis(4-aminophenoxy 4' benzoyl) benzene (1,3-BABB) is modified so that it can be more readily processed to form adhesive bonds, moldings, and composites. The stoichiometric ratio of the two monomers, BTDA and 1,3-BABB is controlled so that the intermediate polyamide acid is of a calculated molecular weight. A polyimide acid with excess anhydride groups is then reacted with the stoichiometrically required amount of monofunctional aromatic or aliphatic amine required for complete endcapping. The stoichiometrically offset, encapped polyimide is processed at lower temperatures and pressures than the unmodified high molecular weight polyimide with the same repeat unit, and exhibits an improved melt stability

Chemical and spectroscopic analysis of olive mill waste water during a biological treatment

The treatment of olive mill waste water was studied on the laboratory scale. Physico–chemical analyses showed the final products had a mean pH of 5.4 without neutralisation and 5.7 when lime was added to the process. Raising the pH by adding lime had a positive outcome on the degradation of phenols, whose levels were reduced by over 76%. The lime also changed the structure of the organic matter, as seen in the infra-red spectra. Combining the FT-IR and 13C NMR data showed that with addition of lime, the density of aliphatic groups decreased to the benefit of aromatic groups, indicating that polymerisation of the organic matter occurred during the bioprocess. Under our experimental conditions, the biotransformation of olive mill waste water appears to favour the stabilisation of the organic matter through mechanisms analogous to those that lead to the formation of humus in the soil

Improvement of the guiding performances of near infrared organic/inorganic channel waveguides

New sol-gel derived organic/inorganic hybrid single mode waveguides devices have been developed for telecommunication applications in the two near infrared windows at 1310 and 1550 nm. The overall procedure of fabrication of these devices is described and the refractive indices of the guiding, the buffer and the protective layers are adjusted by a precise control of the materials' composition. Due to the improvement of the composition of the guiding layer, the attenuation losses are significantly decreased to 0.8 dB/cm and 2dB/cm at respectively 1310 and 1550 nm

The abundances of hydrocarbon functional groups in the interstellar medium inferred from laboratory spectra of hydrogenated and methylated polycyclic aromatic hydrocarbons

Infrared (IR) absorption spectra of individual polycyclic aromatic hydrocarbons (PAHs) containing methyl (-CH3), methylene (>CH2), or diamond-like *CH groups and IR spectra of mixtures of methylated and hydrogenated PAHs prepared by gas phase condensation were measured at room temperature (as grains in pellets) and at low temperature (isolated in Ne matrices). In addition, the PAH blends were subjected to an in-depth molecular structure analysis by means of high-performance liquid chromatography, nuclear magnetic resonance spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Supported by calculations at the density functional theory level, the laboratory results were applied to analyze in detail the aliphatic absorption complex of the diffuse interstellar medium at 3.4 mu-m and to determine the abundances of hydrocarbon functional groups. Assuming that the PAHs are mainly locked in grains, aliphatic CHx groups (x = 1,2,3) would contribute approximately in equal quantities to the 3.4 mu-m feature (N_{CHx} / N_{H} approx 10^{-5} - 2 * 10^{-5}). The abundances, however, may be two to four times lower if a major contribution to the 3.4 mu-m feature comes from molecules in the gas phase. Aromatic =CH groups seem to be almost absent from some lines of sight, but can be nearly as abundant as each of the aliphatic components in other directions (N_{=CH} / N_{H} < 2 * 10^{-5}; upper value for grains). Due to comparatively low binding energies, astronomical IR emission sources do not display such heavy excess hydrogenation. At best, especially in proto-planetary nebulae, >CH2 groups bound to aromatic molecules, i.e., excess hydrogens on the molecular periphery only, can survive the presence of a nearby star.Comment: 34 pages, 19 figures, ApJS, 208, 2

On the viability of the PAH model as an explanation of the unidentified infrared emission features

Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered as the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper we report the result of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal and even artificial spectra) using the theoretical infrared spectra of PAHs from the NASA Ames PAH IR Spectroscopic Database. We show that these non-PAH spectra can be well fitted by PAH mixtures. This suggest that a general match between astronomical spectra and those of PAH mixtures does not necessarily provide definitive support for the PAH hypothesis.Comment: 19 pages, 9 figures, accepted for publication in Ap