Sensing performance of thermal electronic noses: a comparison between ZnO and SnO2 nanowires

In recent times, an increasing number of applications in different fields need gas sensors that are miniaturized but also capable of distinguishing different gases and volatiles. Thermal electronic noses are new devices that meet this need, but their performance is still under study. In this work, we compare the performance of two thermal electronic noses based on SnO2 and ZnO nanowires. Using five different target gases (acetone, ammonia, ethanol, hydrogen and nitrogen dioxide), we investigated the ability of the systems to distinguish individual gases and estimate their concentration. SnO2 nanowires proved to be more suitable for this purpose with a detection limit of 32 parts per billion, an always correct classification (100%) and a mean absolute error of 7 parts per millio

Phenotypic, Molecular and Symbiotic Characterization of the Rhizobial Symbionts of Desmanthus paspalaceus (Lindm.) Burkart That Grow in the Province of Santa Fe, Argentina

Desmanthus paspalaceus (Lindm.) Burkart belongs to the D. virgatus complex, subfamily Mimosoidae. The known potential as livestock fodder of several of these legumes prompted us to undertake a phenotypic, molecular, and symbiotic characterization of the D. paspalaceus symbionts in the Santa Fe province, Argentina. The rhizobia collected—containing isolates with different abiotic-stress tolerances—showed a remarkable genetic diversity by PCR fingerprinting, with 11 different amplification profiles present among 20 isolates. In selected isolates 16S-rDNA sequencing detected mesorhizobia (60%) and rhizobia (40%) within the collection, in contrast to the genus of the original inoculant strain CB3126—previously isolated from Leucaena leucocephala—that we typified here through its 16S rDNA as Sinorhizobium terangae. The results revealed the establishment by diverse bacterial genera -rhizobia, sinorhizobia, and mesorhizobia- of full N2-fixing symbiotic associations with D. paspalaceus. This diversity was paralleled by the presence of at least two different nodC allelic variants. The identical nodC alleles of the Mesorhizobia sp. 10.L.4.2 and 10.L.5.3 notably failed to group within any of the currently described rhizo-/brady-/azorhizobial nodC clades. Interestingly, the nodC from S. terangae CB3126 clustered close to homologs from common bean nodulating rhizobia, but not with the nodC from S. terangae WSM1721 that nodulates Acacia. No previous data were available on nod-gene phylogeny for Desmanthus symbionts. A field assay indicated that inoculation of D. paspalaceus with the local Rhizobium sp. 10L.11.4 produced higher aerial-plant dry weights compared to S. teranga CB3126–inoculated plants. Neither the mesorhizobia 10.L.4.2 or 10.L.5.3 nor the rhizobium 10L.11.4 induced root nodules in L. leucocephala or P. vulgaris. The results show that some of the local isolates have remarkable tolerances to several abiotic stresses including acidity, salt, and temperature; while exhibiting prominent N2 fixation; thus indicating suitability as candidates for inoculation of D. paspalaceus.Fil: Fornasero, Laura Viviana. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: del Papa, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: López, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Albicoro, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Zabala, Juan Marcelo. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Toniutti, Maria Antonieta. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Pensiero, Jose Francisco. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Lagares, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Phenotypic, Molecular and Symbiotic Characterization of the Rhizobial Symbionts of Desmanthus paspalaceus (Lindm.) Burkart That Grow in the Province of Santa Fe, Argentina

Desmanthus paspalaceus (Lindm.) Burkart belongs to the D. virgatus complex, subfamily Mimosoidae. The known potential as livestock fodder of several of these legumes prompted us to undertake a phenotypic, molecular, and symbiotic characterization of the D. paspalaceus symbionts in the Santa Fe province, Argentina. The rhizobia collected - containing isolates with different abiotic-stress tolerances - showed a remarkable genetic diversity by PCR fingerprinting, with 11 different amplification profiles present among 20 isolates. In selected isolates 16S-rDNA sequencing detected mesorhizobia (60%) and rhizobia (40%) within the collection, in contrast to the genus of the original inoculant strain CB3126 - previously isolated from Leucaena leucocephala - that we typified here through its 16S rDNA as Sinorhizobium terangae. The results revealed the establishment by diverse bacterial genera -rhizobia, sinorhizobia, and mesorhizobia- of full N2-fixing symbiotic associations with D. paspalaceus. This diversity was paralleled by the presence of at least two different nodC allelic variants. The identical nodC alleles of the Mesorhizobia sp. 10.L.4.2 and 10.L.5.3 notably failed to group within any of the currently described rhizo-/brady-/azorhizobial nodC clades. Interestingly, the nodC from S. terangae CB3126 clustered close to homologs from common bean nodulating rhizobia, but not with the nodC from S. terangae WSM1721 that nodulates Acacia. No previous data were available on nod-gene phylogeny for Desmanthus symbionts. A field assay indicated that inoculation of D. paspalaceus with the local Rhizobium sp. 10L.11.4 produced higher aerial-plant dry weights compared to S. teranga CB3126-inoculated plants. Neither the mesorhizobia 10.L.4.2 or 10.L.5.3 nor the rhizobium 10L.11.4 induced root nodules in L. leucocephala or P. vulgaris. The results show that some of the local isolates have remarkable tolerances to several abiotic stresses including acidity, salt, and temperature; while exhibiting prominent N2 fixation; thus indicating suitability as candidates for inoculation of D. paspalaceus.Instituto de Biotecnologia y Biologia Molecula

Pheno-genotypic and symbiotic characterization of isolated rhizobia of Desmanthus Virgatus (l.) Willd: In soils of the province of Jujuy (Argentina)

Las leguminosas forrajeras nativas presentan un gran potencial productivo y un ejemplo de ellas es Desmanthus virgatus de amplia distribución en el centro norte de Argentina. El objetivo del trabajo fue realizar una caracterización feno-genotípica y simbiótica de rizobios que forman nódulos en D. virgatus con vista hacia el uso sustentable integral de dicha leguminosa. Para ello, se estableció una colección de 17 aislamientos recuperados de suelos de Jujuy. La caracterización fenotípica permitió reconocer rizobios de crecimiento rápido que mostraron un desarrollo óptimo entre pH 5 y 8, temperaturas de 28 a 35°C, y en concentraciones de 1% (p/v) de NaCl. Se hallaron rizobios con capacidad de crecimiento en condiciones extremas de pH 9 y a 40°C. Los aislamientos se identificaron como pertenecientes a Ensifer spp. y los perfiles de amplificación de ADN genómico mostraron escasa diversidad genética. La inoculación de D. virgatus con la cepa 8L12.1 (Ensifer sp.) produjo incrementos de biomasa seca aérea de 73% en cámara de cultivo y 124% a campo respecto a las plantas sin inocular y sin fertilizar.Native forage legumes have great productive potential and an example of which is Desmanthus virgatus with a wide distribution in central and northern Argentina. The objective of the work was to carry out a pheno-genotypic and symbiotic characterization of rhizobia that form nodules in D. virgatus with a view to the integral sustainable use of said legume. For this, a collection of 17 isolates recovered from Jujuy soils was established. Phenotypic characterization allowed to recognize fast-growing rhizobia that showed an optimal development between pH 5 y 8, temperatures to 28 a 35°C, and in concentrations of 1% (w/v) of NaCl. Rhizobia with growth capacity were found under extreme conditions of pH 9 and at 40°C. The isolates were identified as belonging to Ensifer spp. and the genomic DNA amplification profiles showed little genetic diversity. The inoculation of D. virgatus with the strain 8L12.1 (Ensifer sp.) produced increases of 73% aerial dry biomass in the cultivation chamber and 124% in the field with respect to the uninoculated and unfertilized plants.Fil: Fornasero, Laura Viviana. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Zuber, Nicolás Emilio. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Toniutti, Maria Antonieta. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: del Papa, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; ArgentinaFil: Pensiero, Jose Francisco. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias Agropecuarias del Litoral. Universidad Nacional del Litoral. Instituto de Ciencias Agropecuarias del Litoral; ArgentinaFil: Lagares, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentin

Phenotypic, Molecular and Symbiotic Characterization of the Rhizobial Symbionts of Desmanthus paspalaceus (Lindm.) Burkart That Grow in the Province of Santa Fe, Argentina

Desmanthus paspalaceus (Lindm.) Burkart belongs to the D. virgatus complex, subfamily Mimosoidae. The known potential as livestock fodder of several of these legumes prompted us to undertake a phenotypic, molecular, and symbiotic characterization of the D. paspalaceus symbionts in the Santa Fe province, Argentina. The rhizobia collected - containing isolates with different abiotic-stress tolerances - showed a remarkable genetic diversity by PCR fingerprinting, with 11 different amplification profiles present among 20 isolates. In selected isolates 16S-rDNA sequencing detected mesorhizobia (60%) and rhizobia (40%) within the collection, in contrast to the genus of the original inoculant strain CB3126 - previously isolated from Leucaena leucocephala - that we typified here through its 16S rDNA as Sinorhizobium terangae. The results revealed the establishment by diverse bacterial genera -rhizobia, sinorhizobia, and mesorhizobia- of full N2-fixing symbiotic associations with D. paspalaceus. This diversity was paralleled by the presence of at least two different nodC allelic variants. The identical nodC alleles of the Mesorhizobia sp. 10.L.4.2 and 10.L.5.3 notably failed to group within any of the currently described rhizo-/brady-/azorhizobial nodC clades. Interestingly, the nodC from S. terangae CB3126 clustered close to homologs from common bean nodulating rhizobia, but not with the nodC from S. terangae WSM1721 that nodulates Acacia. No previous data were available on nod-gene phylogeny for Desmanthus symbionts. A field assay indicated that inoculation of D. paspalaceus with the local Rhizobium sp. 10L.11.4 produced higher aerial-plant dry weights compared to S. teranga CB3126-inoculated plants. Neither the mesorhizobia 10.L.4.2 or 10.L.5.3 nor the rhizobium 10L.11.4 induced root nodules in L. leucocephala or P. vulgaris. The results show that some of the local isolates have remarkable tolerances to several abiotic stresses including acidity, salt, and temperature; while exhibiting prominent N2 fixation; thus indicating suitability as candidates for inoculation of D. paspalaceus.Instituto de Biotecnologia y Biologia Molecula

Studio tramite spettroscopia positronica di difetti di tipo vacanza in idruri metallici a base magnesio e di porositá in membrane selettive

Negli ultimi decenni si è vista la nascita di un grande interesse verso l'utilizzo dell'idrogeno come vettore energetico. Le ragioni sono da ricercarsi nelle problematiche sorte in tempi recenti in relazione alle emissioni inquinanti ed al rapido esaurimento delle fonti energetiche. Per poter concepire un'economia basata sull'idrogeno è tuttavia necessario risolvere una serie di problematiche connesse alla sua produzione, immagazzinamento e filtraggio. Il presente lavoro di tesi ha riguardato gli ultimi due punti. In relazione allo stoccaggio del gas, uno dei sistemi più promettenti risulta quello dell'utilizzo d'idruri metallici. Tali materiali presentano ancora una serie di problematiche che ne limitano l'utilizzo pratico, sia in ambito stazionario, che per applicazioni al settore della mobilità. Per superare questi ostacoli è necessaria la comprensione dei meccanismi microscopici con cui avviene la formazione e la dissociazione della fase idruro. Il presente lavoro è stato quindi incentrato sull'approfondimento di tale aspetto, concentrandosi in particolare sul ruolo giocato dai difetti di tipo vacanza in sistemi a base magnesio. Per quanto concerne l'aspetto del filtraggio, le tecniche positroniche sono state impiegate, in concomitanza con altre ad esse complementari, per ottenere una caratterizzazione della porosità, in termini di dimensioni, distribuzione ed interconnettività dei pori, in film di silice da utilizzare per la realizzazione di membrane selettive

Efecto de la inoculación con rizobios y la fertilización fosfatada sobre la nodulación y producción de alfalfa (Medicago sativa L.) en el centro de Santa Fe (Argentina)

La simbiosis entre rizobios y alfalfa (Medicago sativa L.) contribuye a la incorporación de nitrógeno en los agroecosistemas a través de la fijación biológica, que dependerá de la adecuada provisión de nutrientes disponibles en el suelo. El objetivo de este trabajo fue evaluar el efecto de la inoculación con Ensifer meliloti y la fertilización con 0, 20 y 40 kg/ha de fósforo sobre la nodulación y productividad de una pastura de alfalfa en el centro de la provincia de Santa Fe. La inoculación y la aplicación de dosis crecientes de fósforo aumentaron el número de nódulos, biomasa nodular y la producción del forraje de las plantas. La técnica de la inoculación condujo a un incremento de la producción de materia seca entre 23 y 58 % para los tratamientos con el máximo nivel de fertilizante a los 120, 180 y 240 días de la siembra. La adición de la cepa de rizobio utilizada como inoculante y la fertilización fosfatada constituyeron una estrategia favorable para incrementar la producción de alfalfa

Backscattered electrons from surface films deposited on bulk targets: A comparison between computational and experimental results

A Monte Carlo code is described, validated, and utilized to calculate the backscattering coefficient from surface layers of Pd deposited on bulk targets of Si. A quantitative evaluation of the backscattering coefficient as a function of the over-layer thickness is provided, as well as a comparison of the simulated results with experimental data concerning Pd thin films with known thicknesses

Backscattered electrons from gold surface films deposited on silicon substrates: a joint experimental and computational investigation to add new potentiality to electron microscopy

This paper addresses the problem of the thickness determination of thin gold overlayers deposited on silicon bulk substrates by looking at the electron backscattering coefficient involved in scanning electron microscopy (SEM). A Monte Carlo code, used to calculate the backscattering coefficient, together with a simple experimental setup, which uses a conventional SEM, allow to determine thin film thickness (in the range 25–200 nm) with an estimated accuracy of 20%. This adds obviously new potentiality to SEM. Copyright © 2012 John Wiley & Sons, Ltd

Nitrogen-fixing rhizobial strains isolated from <i>Desmodium incanum</i> DC in Argentina: Phylogeny, biodiversity and symbiotic ability

Desmodium spp. are leguminous plants belonging to the tribe Desmodieae of the subfamily Papil-ionoideae. They are widely distributed in temperated and subtropical regions and are used as forageplants, for biological control, and in traditional folk medicine. The genus includes pioneer species thatresist the xerothermic environment and grow in arid, barren sites. Desmodium species that form nitrogen-fixing symbiosis with rhizobia play an important role in sustainable agriculture. In Argentina, 23 nativespecies of this genus have been found, including Desmodium incanum. In this study, a total of 64 D.incanum-nodulating rhizobia were obtained from root nodules of four Argentinean plant populations.Rhizobia showed different abiotic-stress tolerances and a remarkable genetic diversity using PCR fin-gerprinting, with more than 30 different amplification profiles. None of the isolates were found at morethan one site, thus indicating a high level of rhizobial diversity associated with D. incanum in Argentineansoils. In selected isolates, 16S rDNA sequencing and whole-cell extract MALDI TOF analysis revealedthe presence of isolates related to Bradyrhizobium elkanii, Bradyrhizobium japonicum, Bradyrhizobiumyuanmingense, Bradyrhizobium liaoningense, Bradyrhizobium denitrificans and Rhizobium tropici species.In addition, the nodC gene studied in the selected isolates showed different allelic variants.Isolates were phenotypically characterized by assaying their growth under different abiotic stresses.Some of the local isolates were remarkably tolerant to high temperatures, extreme pH and salinity,which are all stressors commonly found in Argentinean soils. One of the isolates showed high tolerance totemperature and extreme pH, and produced higher aerial plant dry weights compared to other inoculatedtreatments. These results indicated that local isolates could be efficiently used for D. incanum inoculation.Instituto de Biotecnologia y Biologia MolecularUniversidad Nacional del Litora