Influence of pollutants in the magneto-dielectric response of silicon nanoparticles.

The influence of the degree of purity of a silicon nanoparticle on its resonances, either electric or magnetic, is assessed by using Mie theory as well as finite-element simulations. In particular, it is shown that the main effect of the increase of absorption due to the pollutants is observed in the magnetic resonances. Concerning Kerker's conditions for the directionality of the scattering [J. Opt. Soc. Am.73, 765 (1983)], it is found that both are strongly shifted when the material's purity is varied. Resistive losses confirm the quenching of magnetic resonances, showing that the region of influence in the magnetic dipole resonance is much larger than in the electric one, although it has been found that losses are not critical for silicon content over 99.50%.

Comprehensive polarimetric analysis of Spectralon white reflectance standard in a wide visible range.

Since polarimetry has extended its use for the study of scattering from surfaces and tissues, Spectralon, a white reflectance standard, is acquiring the role of a polarimetric standard. Both the behavior of Spectralon as a Lambertian surface and its performance as a perfect depolarizer are analyzed in detail. The accuracy of our dynamic polarimeter, together with the polar decomposition to describe the Mueller matrix (MM) depolarizing action, combine to produce a powerful tool for the proper analysis of this scattering surface. Results allowed us to revisit, for confirmation or revision, the role of some MM elements, as described in the bibliography. The conditions under which it can be considered a good Lambertian surface are specified in terms of incidence and scattering angle and verified over a large wavelength range.

Nucleoid-associated PhaF phasin drives intracellular location and segregation of polyhydroxyalkanoate granules in Pseudomonas putida KT2442.

The PhaF is a nucleoid-associated like protein of Pseudomonas putida KT2442 involved in the polyhydroxyalkanoate (PHA) metabolism. Its primary structure shows two modular domains; the N-terminal PHA granule-binding domain (phasin domain) and the C-terminal half containing AAKP-like tandem repeats characteristic of the histone H1 family. Although the PhaF binding to PHA granules and its role as transcriptional regulator have been previously demonstrated, the cell physiology meaning of these properties remains unknown. This work demonstrates that PhaF plays a crucial role in granule localization within the cell. TEM and flow cytometry studies of cells producing granules at early growth stage demonstrated that PhaF directs the PHA granules to the centre of the cells, forming a characteristic needle array. Our studies demonstrated the existence of two markedly different cell populations in the strain lacking PhaF protein, i.e. cells with and without PHA. Complementation studies definitively demonstrated a key role of PhaF in granule segregation during the cell division ensuring the equal distribution of granules between daughter cells. In vitro studies showed that PhaF binds DNA through its C-terminal domain in a non-specific manner. All these findings suggested a main role of PhaF in PHA apparatus through interactions with the segregating chromosome.

Quantum optical response of metallic nanoparticles and dimers.

The optical properties of metallic nanoparticles (NPs) can be described with analytical models based on fundamental quantum mechanical principles, of which the Drude model constitutes the classical limit. Here, we examine the plasmonic properties of silver and gold nanospheres and dimers, with radii ranging from 10 to 1 nm, extending from the classically described regime to the quantum size regime. We have studied the spectral extinction cross section by using the T-matrix method. The results indicate an increasingly substantial change in NP permittivity as the radius is reduced below 5 nm, showing a clear blueshift and weakening of the plasmon resonances for both silver and gold. As a consequence, we observe a dramatic change in the interaction of dimers, especially in the case of gold, where the introduction of quantum mechanically corrected optical properties quenches the plasmonic resonance and predicts an absence of the expected associated redshift.

A ultra-pressure liquid chromatography/triple quadrupole tandem mass spectrometry method for the analysis of 13 eicosanoids in human urine and quantitative 24 hour values in healthy volunteers in a controlled constant diet.

RATIONALE: Isoprostanes (IsoPs) are a series of prostaglandin (PG)-like compounds formed non-enzymatically through free-radical-induced peroxidation of arachidonic acid. They are considered as 'gold-standard' biomarkers for oxidative stress, in general, and lipid peroxidation, in particular. METHODS: A new qualitative and quantitative analytical method for the determination of 13 eicosanoids in human urine using solid-phase extraction (SPE) and ultra-pressure liquid chromatography coupled to tandem mass spectrometry (UPLC/MS/MS) has been developed. The SPE was optimized by comparison of the extraction efficiency and recoveries of three distinct cartridges: Strata X-AW, C18 Sep-Pak, and Oasis HLB. The UPLC/MS/MS approach in the multiple reaction monitoring (MRM) mode was developed using negative electrospray ionization (ESI). RESULTS: The validated method provides a high-throughput assay with an adequate linearity from 0.16 to 330 ng mL(-1). The limit of detection (LOD) and limit of quantification (LOQ) for each analyte showed low intervals (0.021-0.64 ng mL(-1) and 0.042-1.28 ng mL(-1), respectively). Urinary IsoPs were determined in 24 healthy volunteers and ranged from 685 to 3480 ng 24 h(-1) and from 864 to 7511 ng 24 h(-1) in urine from women and men, respectively. CONCLUSIONS: This analytical method could constitute a useful tool for the determination of oxidative stress biomarkers in clinical studies in which IsoPs may evidence early pathological conditions, as suggested by the determination of the baseline IsoPs content in human urine, since it improves upon the detection capacity of previously described methods. The quantity of IsoPs excreted in urine was higher than that found in previous reports due to the total hydrolysis of the conjugated forms.

Polar decomposition of the Mueller matrix: a polarimetric rule of thumb for square-profile surface structure recognition.

In this research, the polar decomposition (PD) method is applied to experimental Mueller matrices (MMs) measured on two-dimensional microstructured surfaces. Polarization information is expressed through a set of parameters of easier physical interpretation. It is shown that evaluating the first derivative of the retardation parameter, δ, a clear indication of the presence of defects either built on or dug in the scattering flat surface (a silicon wafer in our case) can be obtained. Although the rule of thumb thus obtained is established through PD, it can be easily implemented on conventional surface polarimetry. These results constitute an example of the capabilities of the PD approach to MM analysis, and show a direct application in surface characterization.

Ordered metal nanotube arrays fabricated by PVD.

In this work we report a simple method to fabricate ordered arrays of metal nanotubes. This method is based on the deposition of a metal by PVD onto an anodized aluminum oxide (AAO) template. The dimensions of the synthesized nanotubes depend both on the AAO template and on the deposited metal. In fact, it is observed that the aspect ratios of the nanotubes clearly depend significantly on the metal, ranging from 0.6 (Fe) to at least 3 (Zr).

Spontaneous cell fusion in macrophage cultures expressing high levels of the P2Z/P2X7 receptor.

Mouse and human macrophages express a plasma membrane receptor for extracellular ATP named P2Z/P2X7. This molecule, recently cloned, is endowed with the intriguing property of forming an aqueous pore that allows transmembrane fluxes of hydrophylic molecules of molecular weight below 900. The physiological function of this receptor is unknown. In a previous study we reported experiments suggesting that the P2Z/P2X7 receptor is involved in the formation of macrophage-derived multinucleated giant cells (MGCs; Falzoni, S., M. Munerati, D. Ferrari, S. Spisani, S. Moretti, and F. Di Virgilio. 1995. J. Clin. Invest. 95:1207- 1216). We have selected several clones of mouse J774 macrophages that are characterized by either high or low expression of the P2Z/P2X7 receptor and named these clones P2Zhyper or P2Zhypo, respectively. P2Zhyper, but not P2Zhypo, cells grown to confluence in culture spontaneously fuse to form MGCs. As previously shown for human macrophages, fusion is inhibited by the P2Z/P2X7 blocker oxidized ATP. MGCs die shortly after fusion through a dramatic process of cytoplasmic sepimentation followed by fragmentation. These observations support our previous hypothesis that the P2Z/P2X7 receptor is involved in macrophage fusion.

Attachment of magnetite nanoparticles on carbon nanotubes bundles and their response to magnetic fields.

We present an alternative method to control the alignment of carbon nanotube bundles by applying an external magnetic field on magnetic nanoparticles functionalized nanotubes. Carbon nanotubes have been modified by pi-pi stacking of a carboxylic acid and the previously synthesized Fe3O4 nanoparticles have been bounded to the acid groups. Results obtained by TEM, SEM and FESEM show that the magnetite nanoparticles are distributed along the nanotube surfaces, showing a high dispersion and a mean particle size of ca. 4-5 nm. In presence of a magnetic field the modified nanotube bundles have been clearly oriented along the axis parallel to the field.

Post-synthesis alignment of chemically modified carbon nanotubes in magnetic fields.

In this paper we present an improved procedure to prepare carbon nanotubes bundles functionalized with magnetite nanoparticles. Carbon nanotubes (CNTs) have been modified by hydrophobic adsorption of a carboxylic acid derivative and the previously synthesized magnetite nanoparticles have been attached to the acid groups. Electron microscopy studies show a high density of magnetite nanoparticles on the surface of CNTs. These modified carbon nanotubes become magnetic and can be appropriately oriented by using external magnetic fields.

Characterization of nitrogen-doped carbon nanotubes by atomic force microscopy, X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy.

In this work, we perform a comparative study on single-walled carbon nanotubes (CNT) before and after low energy nitrogen ion bombardment (70 eV and 25 x 10-6 A/cm2) at room temperature. The morphology and the mechanical properties were studied by Atomic Force Microscopy (AFM). The bonding configuration of the N-doped CNTs was established by X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Near Edge Spectroscopy (XANES). Single-walled carbon nanotubes were prepared using non-intrusive methods and deposited onto silicon substrates. For the spectroscopic studies, samples with a high concentration of CNTs were analyzed. XPS reveals different chemical states for carbon related to the incorporation of nitrogen. XANES confirms the hexagonal structure of the CNTs, resembling the bonding structure of hexagonal carbon nitrides. AFM images confirm that the CNTs were not destroyed after low energy N2+. The morphology of the original nanotubes maintains after nitrogen ion bombardment except for the incorporation of some pearl-shaped decoration, probably due to the adsorption of some contaminants or to deposition of re-sputtered material. Whereas CNTs improve their adherence to the substrate, this extra granularity on the CNT is easily removed even with the AFM tip. In conclusion, spectroscopic measurements and mechanical properties made clear information on the changes produced on CNT after nitrogen incorporation.

Crown Rot of Zucchini Squash Caused by Fusarium solani f. sp. cucurbitae in Almería Province, Spain.

Cucumber, melon, watermelon, and zucchini are intensively cropped in the southern part of Spain where approximately 20,000 ha of the crops are grown in greenhouses. In the spring of 2007, zucchini plants (Cucurbita pepo) at the fruit-bearing stage in three commercial plastichouses in Almería exhibited necrosis on the basal stem, wilt, and death. The incidence of dead plants was 20 to 30%. Fusarium solani was consistently isolated from the basal stems of symptomatic plants on potato dextrose agar (PDA). Cultures of six single-hyphal transfers were identified on the basis of molecular sequences and morphological characteristics (2). Sequences of ribosomal DNA from ITS1 region, 5.8S rDNA, and ITS2 were identical for all six isolates of F. solani. The rDNA sequence of isolate Fscl-3 of F. solani was deposited as GenBank Accession No. AM940070. The pathogenicity of these six isolates of F. solani was tested in two experiments conducted in one plastichouse in Almería. Pregerminated seeds of zucchini cv. Consul were sown in 1-liter containers filled with vermiculite on 21 May and 22 June, 2007 (experiments 1 and 2, respectively). Plants at the one- to two-true-leaf stage or younger were inoculated with a soil drench of 2.0 to 8.4 × 105 propagules per ml). One colonized PDA petri plate of each isolate was blended and homogenized in 500 ml of distilled water. Inoculum (50 ml per plant) was poured around the stem of zucchini plants growing in vermiculite. The experimental design was a randomized complete block with three replicates with each plot comprising four plants (one plant per container). In both experiments, 12 uninoculated plants of the same cultivar served as controls. Plants were maintained for 1 month following inoculation in a greenhouse with mean temperatures ranging between 20.7 and 24.6°C and 23.3 to 29.8°C for experiments 1 and 2, respectively. Wilting first occurred 9 days after inoculation, and 14 days later, all plants inoculated with the F. solani isolates died. Inoculated plants exhibited lesions on the stem base without rot of secondary roots. At the end of the experiment, the uninoculated plants remained asymptomatic. Results of experiment 2, with higher temperatures, were similar. The pathogen was consistently recovered from symptomatic plants in both experiments, fulfilling Koch's postulates. Although F. solani f. sp. cucurbitae race 1 was reported in field squash (C. maxima) in the province of Valencia of east-central Spain (1), to our knowledge, this is the first report of F. solani as the causal agent of crown rot of zucchini plants in plastichouses in the Almería Province of Spain, one of the world's largest concentrations of greenhouses. References: (1) J. García-Jiménez et al. Plant Dis. 81:1216, 1997. (2) C. M. Messiaen and R. Cassini. Taxonomy of Fusarium. Page 427 in: Fusarium: Diseases, Biology, and Taxonomy. P. E. Nelson et al., eds. Pennsylvania State University, University Park, 1981.

AqquaScan: design and implementation of an internet-based service for the remote monitoring and management of decentralised WWTPs.

This paper describes the design and implementation of AqquaScan, an Internet-based service for remote monitoring and integrated management of decentralised WWTPs. AqquaScan is a multi-user and multi-WWTP service. It has been built according to criteria such as flexibility, scalability and interoperability with the idea of providing an open environment suited to quickly accommodate future scenarios (e.g. incorporation of new plants or upgrading of existing installations). Both, the management of plant information and users interfaces have been implemented in distributed software components that communicate with one another via web services. The implemented web services can be exploited to develop customised user interfaces for visualising the monitored data. By default, a customised web-based client module has been programmed in order for users to be able to exploit the facilities offered within AqquaScan: (1) real-time monitoring of on-line signals; (2) visualisation of historical data; (3) changing operational parameters; (4) notification of time-event information; and (5) storage of measurements from laboratory analysis. At present, AqquaScan is fully operative and is offering supervision services to eleven industrial WWTPs distributed around Northern Spain.

[Effect of Lactobacillus casei on the incidence of infectious conditions in children]. / Efecto de Lactobacillus casei sobre la incidencia de procesos infeeciosos en niñios/as.

AIM: To analyse the effect of continuous consumption of Lactobacillus casei (DN-114001) fermented milk on the incidence of the infectious disorders frequent in children. FIELD: Infant and child population SUBJECTS: children from 3 to 12 years from two schools in Barcelona. A total of 251 children from both sexes participated in the study. INTERVENTIONS: A nutritional intervention study was carried out during 20 weeks with a parallel, prospective, double-blind and randomised by pragmatic clusters design. Participants were children from 3 to 12 years from two schools in Barcelona. One of the centres was assigned to receive two daily units of Actimel" and the other to two units of Placebo. From the 251 participants, 109 receiving placebo and 142 receiving Actimel". Basal demographic characteristics and clinical history data were recorded, and the symptoms related to infectious disorders or other illnesses were monitored at weeks 12, 16 and 20. The analysis of the data was carried out on the intention-to-treat (ITT) population, being the principal endpoint the duration of respiratory and gastrointestinal symptoms. RESULTS: A one day difference, but non-significant, was seen in the median of total duration of days with illness through the study (Actimel group: 1 day vs Placebo group: 2 days). The same nonsignificant difference was also seen in the duration of days with respiratory (high and low respiratory tract infections) and with gastrointestinal (diarrhoea, vomiting, stomach pain and constipation) disorders. There was a statistical significantly difference found in favour of Actimel in the duration of the low respiratory tract infections, bronchitis or pneumonia, and in the duration of fatigue. There was also detected a lower incidence of children with low respiratory tract infections (32% vs. 49%) and with fatigue (3% vs. 13%) in the Actimel group compared to placebo. The satisfaction levels with the nutritional intervention were very high, over 80%. CONCLUSIONS: The study shows a tendency to the reduction of duration and incidence of some infectious disorders in those children receiving two daily Actimel during 20 weeks.

Desensitization and internalization of adenosine A1 receptors in rat brain by in vivo treatment with R-PIA: involvement of coated vesicles.

Chronic treatment of rats with R-PIA 'in vivo' desensitized adenosine A1 receptor-mediated inhibition of adenylyl cyclase in brain plasma membranes and increased basal and forskolin-stimulated adenylyl cyclase. The adenosine A1 receptor agonist CHA (cyclohexyl adenosine) inhibited forskolin-stimulated adenylyl cyclase in synaptic plasma membranes from control rats but failed to do so in membranes isolated from rats treated with R-PIA. This loss of response was accompanied with a significant decrease in both, total number of adenosine A1 receptors and steady-state level of alpha-Gi in synaptic plasma membranes. An increase in the steady-state level of alpha-Gs in synaptic plasma membranes was also observed by R-PIA treatment. Concurrently, a significant increase of adenosine A1 receptors was observed in microsomes and coated vesicles. These results demonstrate adenosine A1 receptor desensitization in rat brain by 'in vivo' treatment with R-PIA and suggest a role for coated vesicles in the internalization of G-protein coupled receptors.

Cytolytic P2X purinoceptors.

Anecdoctal evidence accumulated over almost 20 years has shown that many different cell types are killed by sustained exposure to high concentrations of extracellular ATP. The plasma membrane receptors involved have been pharmacologically characterized and cloned during the last 3 years, and named purinergic P2X. P2X receptors share an intriguing structural relatedness with Caenorhabditis elegans degenerins and mammalian amiloride-sensitive Na channels (ENaCs). Depending on the ATP dose, length of stimulation and receptor subtype, P2X receptor stimulation may cause necrosis or apoptosis. The intracellular pathways activated are poorly known, but the perturbation in intracellular ion homeostasis clearly plays a major role. ICE proteases (caspases) are also triggered, nonetheless their activation is not requested for ATP-dependent cell death. The physiological meaning of P2X receptor-dependent cytotoxicity is not understood, but an involvement in immune-mediated reactions is postulated.

Structural and functional study of a conserved region in the uncoupling protein UCP1: the three matrix loops are involved in the control of transport.

It has been reported that the region 261-269 of the uncoupling protein from brown adipose tissue mitochondria, UCP1, has an important role in the control of its proton translocating activity. Thus the deletion of residues Phe267-Lys268-Gly269 leads to the loss of the nucleotide regulation of the protein, while the complete deletion of the segment leads to the formation of a pore. The region displays sequence homology with the DNA-binding domain of the estrogen receptor. The present report analyzes the structure, by NMR and circular dichroism, of a 20 amino acid residue peptide containing the residues of interest. We demonstrate that residues 263-268 adopt an alpha-helical structure. The helix is at the N-terminal end of the sixth transmembrane domain. The functional significance of this helix has been examined by site-directed mutagenesis of the protein expressed recombinantly in yeasts. Alterations in the structure or orientation of the region leads to an impairment of the regulation, by nucleotides and fatty acids, of the transport activity. UCP1 is one member of the family formed by the carriers of the mitochondrial inner membrane. The family is characterized by a tripartite structure with three repeated segments of about 100 amino acid residues. Two of the mutations have also been performed in the first and second matrix loops and the effect on UCP1 function is very similar. We conclude that the three matrix loops contribute to the formation of the gating domain in UCP1 and propose that they form a hydrophobic pocket that accommodates the purine moiety of the bound nucleotide.

Amyloid beta peptide-induced cholinergic fibres loss in the cerebral cortex of the rat is modified by diet high in lipids and by age.

The influence of diet and age on the effects of intracerebral injection of beta-amyloid peptide (Abeta1-40) in vehicle phosphate-buffered saline (PBS) and on the effects of vehicle alone on cholinergic fibres of the cerebral cortex was studied in rats. The experiments were carried in two groups of animals: one group of young adult rats and a second group of aged rats. Each group of animals, depending on the diet received, was divided into high-cholesterol, high-fat, and a control diet group. In order to evaluate the interaction of Abeta/PBS-cholesterol and of Abeta/PBS-fat, animals without dietary manipulation receiving Abeta and PBS injection were used as controls. High-cholesterol fed animals showed a statistically significant reduction of 49.62% in the number of cholinergic fibres at the Abeta injection site as compared with that at PBS injection site, while the high-fat and control animals showed a significant reduction of 28.13 and 26.81%, respectively. In all diet groups, the loss of cholinergic fibres caused by Abeta as compared to that caused by PBS injection was significantly greater in aged rats in comparison with that observed in the young animals. Furthermore, the results of a multivariate linear regression model revealed that the greatest reduction in cholinergic fibres was in the high-cholesterol fed animals (35 fibres/mm) as compared with that seen in the high-fat and control animals. A significantly greater reduction was also observed at Abeta injection site (28 fibres/mm) as compared with that caused by PBS injection, and a reduction of 16 cholinergic fibres per mm was found in aged animals as compared to that seen in young adult rats. These results show that high-cholesterol diet enhances the toxicity of Abeta peptide and that this is also age-dependent. Therefore, this study increases the evidences of the role of cholesterol in the pathology of Alzheimer's disease (AD).

ATP receptors and giant cell formation.

We have investigated the role of the purinergic P2X7 receptor in the formation of multinucleated giant cells in human monocyte/macrophage cultures stimulated with either concanavalin A or phytohemagglutinin. Macrophage fusion can be blocked by a P2X7-selective pharmacological antagonist or by a mAb directed against the extracellular P2X7 domain. Furthermore, macrophage cell clones expressing high P2X7 levels spontaneously fuse in culture, whereas macrophage clones lacking P2X7 are unable to fuse. Our findings suggest that the newly identified purinergic P2X7 receptor plays a central role in the complex chain of events leading to generation of macrophage-derived giant cells.

Effect of elite physical exercise by triathletes on seven catabolites of DNA oxidation.

The oxidized nucleoside 8-hydroxy-2'-deoxyguanosine has been widely studied as a marker of DNA oxidation; however, data on the occurrence of other metabolites in plasma that are related to DNA damage are scarce. We have applied an improved, sensitive, robust, and reliable method, involving solid phase extraction and ultrahigh-performance liquid chromatography (UHPLC)-tandem mass spectrometry (MS/MS), to the precise quantitation of seven metabolites in the plasma of 15 elite triathletes after a 2-week training program. All compounds were eluted in the first 1.6 min, with limits of detection and quantification ranging between 0.001 and 0.3 ng.mL(-1) and 0.009 and 0.6 ng.mL(-1), respectively. Four compounds were detected in plasma: guanosine-3'-5'-cyclic monophosphate, 8-hydroxyguanine, 8-hydroxy-2'-deoxyguanosine, and 8-nitroguanosine. After two weeks of training, 8-hydroxyguanine exhibited the highest increase (from 0.031 ± 0.008 nM to 0.036 ± 0.012 nM) (p < 0.05), which could be related to the enhanced activity of DNA-repairing enzymes that excise this oxidized base. Increased levels of guanosine-3'-5'-cyclic monophosphate and 8-hydroxy-2'-deoxyguanosine were also observed. In contrast, levels of 8-nitroguanosine (p < 0.05) were significantly reduced, which might be a protective measure as this compound strongly stimulates the generation of superoxide radicals, and its excess is related to pathologies such as microbial (viral) infections and other inflammatory and degenerative disorders. The results obtained indicate an induced adaptive response to the increased oxidative stress related to elite training, and point to the benefits associated with regular exercise.