Search results for "carbon"
showing 10 items of 6057 documents
The heterogeneity of the Mexican lithospheric mantle: Clues from noble gas and CO2 isotopes in fluid inclusions
2022
The abundance of mantle-derived rocks and lavas, in combination with its tectonic evolution, render Mexico a perfect laboratory to investigate the chemical and the isotopic heterogeneity of the lithospheric mantle. New data on the composition of noble gases and CO2in Mexican mantle xenoliths and lavas is reported. Our samples consist of six ultramafic nodules from the Durango Volcanic Field (DVF) and the San Quintin Volcanic Field (SQVF), monogenetic complexes belonging to the Mexican Basin and Range province; and four lavas from the Sierra Chichinautzin (SCN), a Quaternary monogenetic volcanic field located in the Mexican volcanic arc. Ne and Ar isotopes in fluid inclusions reveal mixing b…
Desarrollo de métodos inmunoquímicos para el análisis en alimentos de fungicidas inhibidores de la succinato deshidrogenasa
2017
El uso de plaguicidas constituye una forma eficaz y hoy por hoy necesaria para combatir gran parte de las plagas que afectan a los cultivos agrícolas. Sin embargo, su uso puede dar lugar a la aparición de residuos en los alimentos que llegan al consumidor, lo que puede derivar en un problema de seguridad alimentaria. Por ello, es necesario el desarrollo de métodos analíticos altamente sensibles y selectivos para la monitorización de dichos residuos, que permitan la detección de concentraciones lo más bajas posibles. En este contexto, en esta Tesis Doctoral se ha abordado el desarrollo de métodos inmunoquímicos de elevada sensibilidad y selectividad para el análisis en muestras de alimentos …
Modification of Poly(vinilydenefluoride) Porous Membranes by Grafting of Acrylic Acid Assisted by Supercritical Carbon Dioxide
2010
Aim of this work is to study the preparation of pH sensitive membranes for biomedical applications via thermally induced graft polymerization of acrylic acid (AA) on poly(vinilydenefluoride) (PVDF) assisted by supercritical carbon dioxide (scCO2). Using scCO2 as a solvent and swelling agent, the monomer and the initiator (benzoyl peroxide) could diffuse faster into the polymer matrix, distribute more uniformly and allows a better control of the final molecular architecture promoting grafting reactions rather than chain degradation processes. As polymer matrixes we are using commercial hydrophobic porous PVDF membranes. Grafted polymers are characterized by Fourier transform infrared spectro…
preparazione e caratterizzazione di nanocompositi polimero/CNTs sottoposti a stiro elongazionale
2009
Lo scopo principale di questo lavoro è rivolto alla preparazione di sistemi polimero/CNTs (in particolare a 1 e 3 % in peso di CNTs) e alla caratterizzazione reologica e meccanica dei filamenti in funzione del rapporto di stiro.
Studio sulla relazione tra la resistenza alla kanamicina ed il gene “Putative aminoglycoside 3’-phosphotranferase (PAPH) in Sinorhizobium meliloti ce…
2008
Il ceppo selvatico di Sinorhizobium meliloti 1021 è sensibile alla kanamicina (30 mg/l) anche se Capela et al. (Proc. Natl. Acad. Sci. U.S.A.(2001), 98: 9877-9882), analizzando l’intero genoma, hanno trovato un gene codificante per una “putative aminoglycoside 3'-phosphotransferase” (PAPH), coinvolta nella resistenza ad antibiotici aminoglicosidici quali la kanamicina. Un mutante spontaneo (GM42) kanamicina resistente (200 mg/l) di Sinorhizobium meliloti 1021 è stato caratterizzato da un punto di vista molecolare e fenotipico per analizzare l’attività del gene PAPH. Il ceppo parentale e GM42 sono stati caratterizzati da un punto di vista microbiologico tramite il MicroLog System Biolog. I r…
Isolation, characterization and determination of biotechnological potential of oil-degrading bacteria from Algerian centre coast
2019
Aims The Algerian coastline is exposed to several types of pollution, including hydrocarbons. The aim of this work was to isolate oil-degrading bacteria and to explore the intrinsic bioremediation potential of part of its contaminated harbour. Methods and results A collection of 119 strains, capable to grow on mineral medium supplemented with hydrocarbons, were obtained from polluted sediment and seawater collected from Sidi Fredj harbour (Algiers). Twenty-three strains were selected for further studies. Sequencing of the 16S rRNA gene showed that most isolates belong to genera of hydrocarbonoclastic bacteria (Alcanivorax), generalist hydrocarbons degraders (Marinobacter, Pseudomonas, Gordo…
Investigation of carbonized layer on surface of NaAlSi glass fibers
2013
There are presented and discussed experimental results about carbonate shell on the sodium rich alumosilicate (NaAlSi) glass fibers and carbonization in wet air atmosphere and water uptake kinetic of such fiber fabrics. The analyzes of water uptake kinetic by regression technique, leaching and heating of carbonized glass fabrics helped to separate stages of fast and slow processes between fiber and carbonate shell and air atmosphere. The shell contains mixture of trona and hydrated sodium carbonate. Heating converts both substances to sodium carbonate. The weight uptake after heating encounters two fast exponential processes associated with water absorption on the surface of carbonated shel…
Involvement of an Alkane Hydroxylase System of Gordonia sp. Strain SoCg in Degradation of Solid n-Alkanes▿
2010
ABSTRACT Enzymes involved in oxidation of long-chain n -alkanes are still not well known, especially those in Gram-positive bacteria. This work describes the alkane degradation system of the n -alkane degrader actinobacterium Gordonia sp. strain SoCg, which is able to grow on n -alkanes from dodecane (C 12 ) to hexatriacontane (C 36 ) as the sole C source. SoCg harbors in its chromosome a single alk locus carrying six open reading frames (ORFs), which shows 78 to 79% identity with the alkane hydroxylase (AH)-encoding systems of other alkane-degrading actinobacteria. Quantitative reverse transcription-PCR showed that the genes encoding AlkB (alkane 1-monooxygenase), RubA3 (rubredoxin), RubA4…
Influence of low methoxyl pectin gel textures and in vitro release of rutin from calcium pectinate beads.
2013
This study described the preparation and characterization of low methoxyl pectin (LMP) gels and beads for controlled release applications. The rheological characterization of the various formulations was proposed. Then the mechanical and morphological characterizations of beads were determined. Finally, the controlled release studies taking rutin as a model drug was evaluated. The results showed that Young's modulus values of non-amidated LMP gels decrease when adding up to 15% sorbitol. Calcium pectinate beads loaded with rutin are about 600 μm, oblong shaped with dense matrix. Beads containing sodium bicarbonate showed about 80% lower rutin encapsulation efficiency by increasing the pH of…
Isolation of Gram-positive n-alkane degraders from a hydrocarbon-contaminated Mediterranean shoreline.
2007
Aims: To investigate the petroleum hydrocarbon (HC)-degrading potential of indigenous micro-organisms in a sandy Mediterranean coast, accidentally contaminated with petroleum-derived HCs. Methods and Results: Using culturable methods, a population of Gram-positive n-alkane degraders was detected in the contaminated soil. Five isolates, identified as one Nocardia, two Rhodococcus and two Gordonia strains, were able to degrade medium- and long-chain n-alkanes up to C36 as assessed by growth assays and gas chromatography-mass spectrometry analysis. Diverging alkane hydroxylase-encoding genes (alkB) were detected by PCR, using degenerated primers, in all the strains; multiple sequences were obt…