Search

Dietary glycerol supplementation in aquaculture feed is seen as an alternative and inexpensive way to fuel fish metabolism, attenuate metabolic utilization of dietary proteins and, subsequently, reduce nitrogen excretion. In this study, we evaluated the impact of dietary glycerol supplementation on nitrogen excretion of European seabass (Dicentrarchus labrax) and its effects on metabolite profile and bacterial community composition of gut digesta. These effects were evaluated in a 60-day trial with fish fed diets supplemented with 2.5% or 5% (w/w) refined glycerol and without glycerol supplementation. Nuclear magnetic resonance spectroscopy and high-throughput 16S rRNA gene sequencing were used to characterize the effects of glycerol supplementation on digesta metabolite and bacterial community composition of 6-h postprandial fish. Our results showed that ammonia excretion was not altered by dietary glycerol supplementation, and the highest glycerol dosage was associated with significant increases in amino acids and a decrease of ergogenic creatine in digesta metabolome. Concomitantly, significant decreases in putative amino acid degradation pathways were detected in the predicted metagenome analysis, suggesting a metabolic shift. Taxon-specific analysis revealed significant increases in abundance of some specific genera (e.g., Burkholderia and Vibrio) and bacterial diversity. Overall, our results indicate glycerol supplementation may decrease amino acid catabolism without adversely affecting fish gut bacterial communities. Key points • Glycerol can be an inexpensive and energetic alternative in fish feed formulations. • Glycerol did not affect nitrogen excretion and gut bacteriome composition. • Glycerol reduced uptake of amino acids and increased uptake of ergogenic creatine. • Glycerol reduced putative amino acid degradation pathways in predicted metagenome.

The integration of optomechanics and optoelectronics in a single device opens new possibilities for developing information technologies and exploring fundamental phenomena. Gallium arsenide (GaAs) is a well-known material that can bridge the gap between the functionalities of optomechanical devices and optical gain media. Here, we experimentally demonstrate a high-frequency GaAs optomechanical resonator with a ring-type bullseye geometry that is unprecedented in this platform. We measured mechanical modes up to 3.4 GHz with quality factors of 4000 (at 77 K) and optomechanical coupling rates up to 39 kHz at telecom wavelengths. Moreover, we investigated the material symmetry break due to elastic anisotropy and its impact on the mechanical mode spectrum. Finally, we assessed the temperature dependence of the mechanical losses and demonstrated the efficiency and anisotropy resilience of the bullseye anchor loss suppression, indicating that lower temperature operation may allow mechanical quality factors over $10^4$. Such characteristics are valuable for active optomechanics, coherent microwave-to-optics conversion via piezo-mechanics and other implementations of high-frequency oscillators in III-V materials., 8 pages, 5 figures

We fabricated and measured a GaAs bullseye resonator able to operate above 3 GHz when coupled to whispering gallery optical modes. Our large phononic bandgap allowed us to observe the symmetry break caused by the material anisotropy and obtain optomechanical coupling rates above 30 kHz.

Hydrocarbon bioremediation in anoxic sediment layers is still challenging not only because it involves metabolic pathways with lower energy yields but also because the production of biosurfactants that contribute to the dispersion of the pollutant is limited by oxygen availability. This work aims at screening populations of culturable hydrocarbonoclastic and biosurfactant (BSF) producing bacteria from deep sub-seafloor sediments (mud volcanos from Gulf of Cadiz) and estuarine sub-surface sediments (Ria de Aveiro) for strains with potential to operate in sub-oxic conditions. Isolates were retrieved from anaerobic selective cultures in which crude oil was provided as sole carbon source and different supplements were provided as electron acceptors. Twelve representative isolates were obtained from selective cultures with deep-sea and estuary sediments, six from each. These were identified by sequencing of 16S rRNA gene fragments belonging to Pseudomonas, Bacillus, Ochrobactrum, Brevundimonas, Psychrobacter, Staphylococcus, Marinobacter and Curtobacterium genera. BSF production by the isolates was tested by atomized oil assay, surface tension measurement and determination of the emulsification index. All isolates were able to produce BSFs under aerobic and anaerobic conditions, except for isolate DS27 which only produced BSF under aerobic conditions. These isolates presented potential to be applied in bioremediation or microbial enhanced oil recovery strategies under conditions of oxygen limitation. For the first time, members of Ochrobactrum, Brevundimonas, Psychrobacter, Staphylococcus, Marinobacter and Curtobacterium genera are described as anaerobic producers of BSFs.

We propose a compact Si3N4 Photonic Molecule for robust and differential measurements in sensing applications. The simulations show that a refractive index sensitivity of 131.3 nm/RIU with high thermal stability can be achieved.

Endocrine disrupting compounds (EDCs) are considered as high research priority being a source of potential adverse ecological health effects in environmental waters. 17β-Estradiol (E2), a recalcitrant natural estrogen, is typically encountered in wastewater treatment plants (WWTPs) at levels ranging 10-30ngL-1 in the influent flow and 1-3ngL-1 in the effluent flow. The exposure to even extremely low concentrations of E2 may interfere with the normal function of the endocrine system of organisms. In this study, five bacteria isolated from enrichment cultures of sediments of mud volcanoes of the Gulf of Cadiz (Moroccan-Iberian margin) were identified as aerobic E2 biodegraders, which produce low amounts of biotransformed estrone (E1). Analysis of 16S rDNA gene sequences identified three of them as Virgibacillus halotolerans, Bacillus flexus and Bacillus licheniformis. Among the set of strains, Bacillus licheniformis showed also ability to biodegrade E2 under anaerobic conditions.

The recent rise and development of photonic devices have created a need for efficient alignment techniques of optical fibers to integrated devices. The Device Research Laboratory (LPD) – IFGW-UNICAMP currently uses micropositioners for alignment. This project aims to develop and fabricate V-grooves as an alternative method. The grooves were fabricated on silicon wafers, using HF isotropic wet etching and KOH anisotropic wet etching. Etching rate for KOH and HF were determined as in 2.09 ± 0.08 ?m/min and 127 ± 4 nm/min, respectively. The first V-grooves were successfully fabricated and characterized by optical microscopy. The project is still ongoing, and fiber-to-fiber coupling tests using V-grooves are yet still to be done. Two optical fibers will be coupled using micropositioners and then the same fibers will be coupled using V-grooves. Both efficiencies will be compared in order to confirm V-grooves as an effective autoalignment method.

There is a growing consensus that future technological developments of aquaculture systems should account for the structure and function of microbial communities in the whole system and not only in fish guts. In this study, we aimed to investigate the composition of bacterioplankton communities of a hatchery recirculating aquaculture system (RAS) used for the production of Senegalese sole (Solea senegalensis) juveniles. To this end, we used a 16S rRNA gene based denaturing gradient gel electrophoresis (DGGE) and pyrosequencing analyses to characterize the bacterioplankton communities of the RAS and its water supply. Overall, the most abundant orders were Alteromonadales, Rhodobacterales, Oceanospirillales, Vibrionales, Flavobacteriales, Lactobacillales, Thiotrichales, Burkholderiales and Bdellovibrionales. Although we found a clear distinction between the RAS and the water supply bacterioplankton communities, most of the abundant OTUs (≥50 sequences) in the hatchery RAS were also present in the water supply. These included OTUs related to Pseudoalteromonas genus and the Roseobacter clade, which are known to comprise bacterial members with activity against Vibrio fish pathogens. Overall, in contrast to previous findings for sole grow-out RAS, our results suggest that the water supply may influence the bacterioplankton community structure of sole hatchery RAS. Further studies are needed to investigate the effect of aquaculture practices on RAS bacterioplankton communities and identification of the key drivers of their structure and diversity.

We report our recent progress on silicon-based photonic molecules. Continuously tunable mode-; athermal sensors; resonant optical amplification, and hybrid III-V on Si lasers are presented.

We demonstrate a composite coupling between optical fields, acoustic modes and thermal expansion in gallium arsenide microdisks. A relationship between optical detuning and mechanical frequency diverse from traditional optomechanical theory is also observed.

We experimentally investigate a ferrofluid-clad silicon microring resonator-based magnetic field sensor. The device presents relatively high loaded quality factors (∼ 6,000) and resonance shifts of 185 pm in response to 110 Oe strong magnetic field.

We demonstrate a self-amplified filter based on Silicon Ring Resonators with Er-doped cladding. It is capable of filtering and routing resonant wavelengths, with simultaneous signal amplification. An equivalent internal gain of 4.7 dB/mm was observed.

RATIONALE The photodynamic process involves the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of oxidizing biological molecules, such as lipids. However, the effect of the photodynamic process in the bacterial phospholipid profile by a photosensitizer has never been reported. A lipidomic approach was used to study the photodynamic oxidation of membrane phospholipids of Staphylococcus warneri by a tricationic porphyrin [5,10,15-tris(1-methylpyridinium-4-yl)-20-(pentafluorophenyl)porphyrin triiodide, Tri-Py(+)-Me-PF]. METHODS S. warneri (10(8) colony forming units mL(-1)) was irradiated with white light (4 mW cm(-2), 21.6 J cm(-2)) in the presence of Tri-Py(+)-Me-PF (5.0 μM). Non-photosensitized bacteria were used as control (irradiated without porphyrin). After irradiation, total lipids were extracted and separated by thin-layer chromatography (TLC). Isolated fractions of lipid classes were quantified by phosphorus assay and analyzed by mass spectrometry (MS): off-line TLC/ESI-MS, hydrophilic interaction (HILIC)-LC/MS and MS/MS. RESULTS The most representative classes of S. warneri phospholipids were identified as phosphatidylglycerols (PGs) and cardiolipins (CLs). Lysyl-phosphatidylglycerols (LPGs), phosphatidylethanolamines (PEs), phosphatidylcholines (PCs) and phosphatidic acids (PAs) were also identified. After photodynamic treatment, an overall increase in the relative abundance of PGs was observed as well as the appearance of new oxidized species from CLs, including hydroxy and hydroperoxy derivatives. Formation of high amounts of lipid hydroperoxides was confirmed by FOX2 assay. Photodynamic oxidation of phospholipid standards revealed the formation of hydroperoxy and dihydroperoxy derivatives, confirming the observed CL oxidized species in S. warneri. CONCLUSIONS Membrane phospholipids of S. warneri are molecular targets of the photoinactivation process induced by Tri-Py(+) -Me-PF. The overall modification in the relative amount of phospholipids and the formation of lipid hydroxides and hydroperoxides indicate the lethal damage caused to photosensitized bacterial cells.

We experimentally investigate the application of magnetic fluids (MFs) on integrated silicon photonics. Using a ferrofluid-clad silicon microring resonator, we demonstrate active control of resonances by applying an external magnetic field. Relatively high loaded quality factors on the order of 6000 are achieved, despite the optical losses introduced by the magnetic nanoparticles. We demonstrate resonance shifts of 185 pm in response to a 110 Oe strong magnetic field, corresponding to an overall refractive index change of −3.2×10−3 for the cladding MF. The combination of MFs and integrated photonics could potentially lead to the development of magnetically controllable optical devices and ultra-compact cost-effective magnetic field sensors.

This study aimed to assess the effect of ultraviolet radiation (UVR) and chemical stress (triclosan-TCS; potassium dichromate-PD; prochloraz-PCZ) on bacterial communities of zebrafish (Danio rerio) embryos (ZEBC). Embryos were exposed to two UVR intensities and two chemical concentrations not causing mortality or any developmental effect (equivalent to the No-Observed-Effect Concentration-NOEC; NOEC diluted by 10-NOEC/10). Effects on ZEBC were evaluated using denaturing gradient gel electrophoresis (DGGE) and interpreted considering structure, richness and diversity. ZEBC were affected by both stressors even at concentrations/doses not affecting the host-organism (survival/development). Yet, some stress-tolerant bacterial groups were revealed. The structure of the ZEBC was always affected, mainly due to xenobiotic presence. Richness and diversity decreased after exposure to NOEC of PD. Interactive effects occurred for TCS and UVR. Aquatic microbiota imbalance might have repercussions for the host/aquatic system, particularly in a realistic scenario/climate change perspective therefore, future ecotoxicological models should consider xenobiotics interactions with UVR. published

International audience; This work reports the design and fabrication of silicon nitride-based microresonators by employing DUV optical lithography and ICP-RIE plasma etching. Microring devices with high Q factors provide high sensitivity and low detection limit, enabling their use in biochemical sensing applications. With these properties, the devices can be used to detect and quantify the biomolecules present in a homogeneous solution, by detecting an effective refractive index change, without using fluorescent labels.

We compare the environmental characteristics and bacterial communities associated with two rushes, Juncus maritimus and Bolboschoenus maritimus, and adjacent unvegetated habitat in a salt marsh subjected to historical mercury pollution. Mercury content was higher in vegetated than unvegetated habitat and increased with sampling depth. There was also a significant relationship between mercury concentration and bacterial composition. Habitat (Juncus, Bolboschoenus or unvegetated), sample depth, and the interaction between both, however, explained most of the variation in composition (∼70%). Variation in composition with depth was most prominent for the unvegetated habitat, followed by Juncus, but more constrained for Bolboschoenus habitat. This constraint may be indicative of a strong plant–microbe ecophysiological adaptation. Vegetated habitat contained distinct bacterial communities associated with higher potential activity of aminopeptidase, β-glucosidase and arylsulphatase and incorporation rates of 14C-glucose and 14C-acetate. Communities in unvegetated habitat were, in contrast, associated with both higher pH and proportion of sulphate reducing bacteria.

We have fabricated highly luminescent samples with erbium-doped amorphous silicon suboxide $(a\hbox{-SiO}_{x} \langle \hbox{Er}\rangle)$ layers on $\hbox{SiO}_{2}/\hbox{Si}$ substrates. The layers are designed to provide a resonance with large modal overlap with the active material and with low quality factor (Q-factor) at 1540 nm. Also, the structure has higher Q-factor resonances in the wavelength range between 800 and 1000 nm. Within this range, strong light emission from $a\hbox{-SiO}_{x}$ defect-related radiative centers and emission from the $\hbox{Er}^{3+}\,{}^{4}{ \rm I}_{11/2} - ^{4}{\rm I}_{15/2}$ optical transition (980 nm) are observed. A twofold and fourfold improvement in photoluminescence (PL) intensity are achieved in the wavelength ranges between 800 and 1000 nm and between 1500 and 1600 nm (region of $\hbox{Er}^{3+}\,{}^{4}{\rm I}_{13/2} - {}^{4}{\rm I}_{15/2}$ transition), respectively, when compared to the $a\hbox{-SiO}_{x} \langle \hbox{Er} \rangle$ active material deposited directly on Si substrate. The latter higher PL intensity enhancement is apparently caused by optical pumping at 980 nm (higher Q-factor) with subsequent emission from the ${}^{4}{\rm I}_{15/2}$ level in the low Q-factor resonance at 1540 nm. Further, five times increase of this emission at 1540 nm is obtained after optimized temperature annealing. The temperature-induced quenching in the PL intensity indicates distinct deactivation energies related to different types of Er centers which are more or less coupled to defects depending on the thermal treatment temperature

This work reports the photophysical and biological evaluation of five cationic porphyrins as photosensitizers (PS) for the photodynamic inactivation (PDI) of Penicillium chrysogenum conidia. Two different cationic porphyrin groups were synthesized from 5,10,15,20-tetrakis(4-pyridyl)porphyrin and 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin. The photostability and singlet oxygen generation studies showed that these molecules are photostable and efficient singlet oxygen generators. PDI experiments of P. chrysogenum conidia conducted with 50 mmol L-1 of photosensitiser under white light at a fluence rate of 200 mW cm-2 over 20 min showed that the most effective PS caused a 4.1 log reduction in the concentration of viable conidia. The present results show that porphyrins 1a and 1b are more efficient PSs than porphyrin 2a while porphyrins 1c and 2b show no inactivation of P. chrysogenum. It is also clear that the effectiveness of the molecule as PS for antifungal PDI is strongly related with the porphyrin substituent groups, and consequently their solubility in physiological media. The average amount of PS adsorbed per viable conidium was a determining factor in the photoinactivation efficiency and varied between the different studied PSs. Cationic PSs 1a and 1b might be promising anti-fungal PDI agents with potential applications in phytosanitation, biofilm control, bioremediation, and wastewater treatment. Thanks are due to the Portuguese Foundation for Science and Technology (FCT) and FEDER, for funding the QOPNA and CESAM research groups, and the Portuguese National NMR Network. This work had financial support from project PTDC/QUI/65228/2006. M. C. Gomes was financed by the BI grant (BI/UI55/4856/2010) and S. M. Woranovicz-Barreira is thankful to Federal University of Paraná, Brazil, for her leave of absence. The authors are also grateful to Prof. Charles Drain for helpful discussions, and to Dr Artur Alves for the molecular confirmation of the identification of the fungal strain. published

The effects of sewage sludge selectively enriched with Cd and Zn, both singly and in combination, on the bacterial, fungal, Alphaproteobacteria and Actinobacteria communities of a soil under arable or grassland management were studied with a PCR-DGGE approach. The effects of Cd and Zn were evaluated after a short time (7 d) when the Cd and Zn solubility were low and the C availability was high, and again after 180 d when the labile sludge C was mineralized and the effects of heavy metals predominated. In the arable soil all treatments induced significant short-term changes in the studied microbial groups, and long-term changes were observed in Actinobacteria and fungal communities. In the grassland soil, all treatments induced significant short-term changes in the studied microbial groups except for Alphaproteobacteria and fungi, and long-term effects on the actinobacteria and fungal communities. It was concluded that incorporation of Cd- and Zn-rich sludge into soils may have both short- and long-term effects on various bacterial phylogenetic groups whereas the metals may be better tolerated by the dominant soil fungi. In this study the impact was greater in arable than in grassland soil. published

We present the growth of stacked layers of InAs quantum dots directly on high bandgap In 0.68 Ga 0.32 As 0.7 P 0.3 ( λ g =1420 nm) barriers. The quaternary material is lattice matched to InP forming a double hetero-structure. Indium flux, number of InAs stacked layers and InGaAsP inner separation layer thickness were investigated. Photoluminescence (PL) and atomic force microscopy (AFM) analysis indicate the occurrence of gallium diffusion and the arsenic/phosphorus (As/P) exchange with the InGaAsP barriers. As a result, shorter wavelength emission is observed, making the structures suitable for telecom applications.

Polycyclic aromatic hydrocarbon (PAH) pollutants originating from oil spills and wood and fuel combustion are pollutants which are among the major threats to mangrove ecosystems. In this study, the composition and relative abundance in the sediment bacterial communities of naphthalene dioxygenase ( ndo ) genes which are important for bacterial adaptation to environmental PAH contamination were investigated. Three urban mangrove sites which had characteristic compositions and levels of PAH compounds in the sediments were selected. The diversity and relative abundance of ndo genes in total community DNA were assessed by a newly developed ndo denaturing gradient gel electrophoresis (DGGE) approach and by PCR amplification with primers targeting ndo genes with subsequent Southern blot hybridization analyses. Bacterial populations inhabiting sediments of urban mangroves under the impact of different sources of PAH contamination harbor distinct ndo genotypes. Sequencing of cloned ndo amplicons comigrating with dominant DGGE bands revealed new ndo genotypes. PCR-Southern blot analysis and ndo DGGE showed that the frequently studied nah and phn genotypes were not detected as dominant ndo types in the mangrove sediments. However, ndo genotypes related to nagAc -like genes were detected, but only in oil-contaminated mangrove sediments. The long-term impact of PAH contamination, together with the specific environmental conditions at each site, may have affected the abundance and diversity of ndo genes in sediments of urban mangroves.

This work presents the selective growth of three-dimensional metallic gallium nitride structures on silicon substrates by chemical beam epitaxy (CBE) with a subsequent plasma nitridation process. The use of titanium pre-deposited stripes over silicon (1 0 0) is shown to provide high selectivity where spherical and semi-spherical structures are obtained only over the metal. These structures have diameters ranging from 100 nm to 3 μm depending on the growth conditions. The nitridation process was performed on an electron cyclotron resonance (ECR) plasma system. Raman micro-spectroscopy results showed GaN formation with zinc blend crystal structure and photoluminescence emission in the visible spectrum in a range between 350 and 650 nm.

Ge nanocrystallites (Ge-nc) have been formed by ion implantation of Ge+74 into SiO2 matrix, thermally grown on p-type Si substrates. The Ge-nc are examined by Raman spectroscopy, photoluminescence (PL) and Fourier transform infrared spectroscopy (FTIR). The samples were prepared with various implantation doses [0.5; 0.8; 1; 2; 3; 4] × 1016 cm−2 with 250 keV energy. After implantation, the samples were annealed at 1,000 °C in forming gas atmosphere for 1 h. Raman intensity variation with implantation doses is observed, particularly for the peak near 304 cm−1. It was found that the sample implanted with a doses of 2 × 1016 cm−2 shows maximum photoluminescence intensity at about 3.2 eV. FTIR analysis shows that the SiO2 film moved off stoichiometry due to Ge+74 ion implantation, and Ge oxides are formed in it. This result is shown as a reduction of GeOx at exactly the doses corresponding to the maximum blue-violet PL emission and the largest Raman emission at 304 cm−1. This intensity reduction can be attributed to a larger portion of broken Ge–O bonds enabling a greater number of Ge atoms to participate in the cluster formation and at the same time increasing the oxygen vacancies. This idea would explain why the FTIR peak decreases at the same implantation doses where the PL intensity increases.

We demonstrate the generation and control of optical resonance mode-splitting arising from a single-notch resonance using coupled silicon microring resonators with electrically controlled counter-propagating mode excitation.

Yoshimoto et al. [Anal. Chem. 2002, 74, 4306-4309] reported that a quartz crystal microbalance or QCM changed its response to sucrose solutions according to its angle of immersion. The effect was tentatively attributed to gravity-caused stress on the viscous interface between the oscillator and the bulk solution. The present work reports results from QCM experiments carried out so that any effect of gravity on the interfacial region would be magnified. This permitted use of a lower-frequency, less-sensitive QCM. Molecules of DNA were tethered to a functionalized QCM surface and then extended in steps, via sandwich hybridization, to produce DNA of uniform and known length. This feature allowed both the effect of QCM immersion angle and the relationship between frequency and molecular length to be investigated simultaneously. Comparison of acoustic wave damping at 0 degrees and 180 degrees immersion angles offers compelling evidence that the interfacial region expands when the active face of the QCM is down and contracts when it is up. This is apparently a consequence of the interfacial region being more dense than the bulk solution. The results are consistent with (a) slow gravity-driven movement of molecules away from a down-facing QCM, (b) rapid hybridization-driven movement away from an up-facing QCM, and (c) a QCM frequency response that decreases according to a simple exponential function of the tethered molecules' radius of gyration.

We present an investigation of beryllium doping selectivity in InGaP layers grown by chemical beam epitaxy on pre-patterned substrates. We observed a resistivity of 3.1×10 −2 and 4.5×10 −2 Ω cm for (1 1 1)A planes with the growth at 500°C and 540°C, respectively. The layers on (0 0 1) planes show a resistivity of 8.9×10 −1 Ω cm with the growth at 500°C, being essentially undoped with the growth at 540°C ⋅ We show how this strong doping selectivity can be explained by Be 3 P 2 cluster formation growth, which depends on growth temperature and planar crystalline structure.

Five strains of Rhodotorula mucilaginosa were tested for the ability to accumulate free and complexed silver ions by metabolism-dependent and -independent processes. The ability to take up Ag+ was observed in both live and dead biomass, whereas silver dicyanide [Ag (CN)2-] uptake was strictly glucose dependent. In contrast to Ag (CN)2-, glucose addition inhibited by 16 to 25% the Ag+ uptake rate of living UFMG - Y02, Y27, and Y35 cells, while strains CBS 316 and UFMG-Y01 showed an improved uptake rate of about 115% and 13%, respectively. The Langmuir sorption model was used to evaluate the silver sorption capability of the R. mucilaginosa strains. The calculated q max value suggested that R. mucilaginosa strains UFMG-Y27 had the highest loading capacity. The type strain CBS 316 had the lowest q max but showed the highest affinity for silver ions. The results provided by the Fourier Transform Infra Red analysis (FTIR) suggest that C=O groups represent the main reactive site for silver uptake by the strain UFMG-Y27. Quatro linhagens de Rhodotorula mucilaginosa e uma linhagem padrão dessa mesma espécie foram investigadas quanto a habilidade de acumular íons de prata livres (Ag+) e complexados [Ag (CN)2-], através de processos dependentes e independentes do metabolismo. A habilidade de acumular Ag+ foi observada em ambas as células, vivas e mortas. Contudo, o acúmulo de Ag (CN)2- foi um processo estritamente dependente de energia. Durante os estudos que avaliaram a dependência de uma fonte energética para o acumulo de íons de prata livres (Ag+) foi observado que a adição de glicose resultou na diminuição do acúmulo de Ag+ por três linhagens (UFMG -- Y02, 27 and 35). Ao passo que as linhagens CBS 316 e UFMG -- Y01 apresentaram aumento do acúmulo desse metal. A analise dos resultados de biossorção através do modelo de Langmuir, sugerem que a linhagem UFMG -- Y27 possui a maior capacidade de acúmulo de prata (carga). Enquanto que a linhagem padrão CBS 316 apresentou a menor capacidade de carga e a maior afinidade por ions de prata. Analises de infra vermelho da biomassa fúngica, com e sem prata, mostraram que os grupamentos C=O foram os principais sítios de ligação desse metal pela linhagem UFMG -- Y27.

We describe the integration of erbium-doped Al 2 O 3 material with InGaAs/GaAs quantum well lasers emitting at 980 nm, demonstrating the possibility of integrating III–V based pumping lasers and materials suitable for optical amplification and planar photonics. Combining Er-doped materials with III–V compounds is challenging since ion activation usually requires high temperature annealing. In order to demonstrate the compatibility of the two material systems we fabricated laser samples using Er-doped Al 2 O 3 films as insulating material. We compare annealed (800°C) and non-annealed devices and show that laser performance is not affected by the high-temperature annealing.

Silicon nitride films deposited by low-pressure electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-CVD) at room temperature are proposed for nonlinear optics applications in the telecommunications C-band. Numerical simulations were performed to determine the relationship between refractive index and the waveguide minimum size in order to have the zero dispersion point at 1.55 µm. Silicon nitride films with large thickness, low roughness and high refractive index were obtained by varying deposition parameters, such as gas pressure (4–6 mTorr) and Si/N ratio. The Si-rich silicon nitride film developed for nonlinear applications with refractive index of 2, high deposition rate, low hydrogen concentration and low roughness was used for fabrication of nonlinear microring resonators. Using the deposition process at low temperature, the stress limitation in thick silicon nitride films was eliminated.

The surface microlayer (SML) is characterized by different physicochemical properties from underlying waters (UW). However, whether these differences in abiotic factors underlie the distinct sensitivity of bacterioneuston (i.e. SML bacteria) and bacterioplankton to environmental stressors remains to be addressed. We investigated the contribution of abiotic factors to the UV-B sensitivity of bacterioneuston and bacterioplankton. Nutrients (especially nitrogen and phosphate) emerged as important determinants of bacterial UV-B sensitivity. The role of particles, nutrients, and dissolved organic components on bacterial UV-B sensitivity was further evaluated using dilution cultures. Filtered samples were twofold more UV sensitive than unfiltered samples, suggesting a UV-protective effect of particles. High nutrient concentrations attenuated bacterial UV-B sensitivity (up to 40%), compared with unamended conditions, by influencing bacterial physiology and/or community composition. Suspending cells in natural water, particularly from the SML, also attenuated UV-B sensitivity (up to 23%), compared with suspension in an artificial mineral solution. Bioassays using Pseudomonas sp. strain NT5I1.2B revealed that chemical water properties influence UV-induced oxidative damage. UV-B sensitivity was associated with high cell-specific activities. The chemical environment of the SML and UW influences UV-B effects on the corresponding bacterial communities. Maintaining low cell activities might be advantageous in stressful environments, like the SML.

Aquaculture facilities worldwide continue to experi-ence significant economic losses because of disease caused by pathogenic bacteria, including multidrug-resistant strains. This scenario drives the search for alternative methods to inactivate pathogenic bacteria. Phage therapy is currently considered as a viable alternative to antibiotics for inactivation of bacterial pathogens in aquaculture systems. While phage therapy appears to represent a useful and flexible tool for microbiological decontamination of aquaculture effluents, the effect of physical and chemical proper-ties of culture waters on the efficiency of this tech-nology has never been reported. The present study aimed to evaluate the effect of physical and chemical properties of aquaculture waters (e.g. pH, tempera-ture, salinity and organic matter content) on the efficiency of phage therapy under controlled experi-mental conditions in order to provide a basis for the selection of the most suitable protocol for subse-quent experiments. A bioluminescent genetically transformed Escherichia coli was selected as a model microorganism to monitor real-time phage therapy kinetics through the measurement of bioluminescence, thus avoiding the laborious and time-consuming conventional method of counting colony-forming units (CFU). For all experiments, a bacterial concentration of ≈ 10 5 CFU ml −1 and a phage concentration of ≈ 10 6–8 plaque forming unit ml −1 were used. Phage survival was not significantly affected by the natural variability of pH (6.5–7.4), temperature (10–25°C), salinity (0–30 g NaCl l −1) and organic matter concentration of aquaculture waters in a tem-perate climate. Nonetheless, the efficiency of phage therapy was mostly affected by the variation of salin-ity and organic matter content. As the effectiveness of phage therapy increases with water salt content, this approach appears to be a suitable choice for marine aquaculture systems. The success of phage therapy may also be enhanced in non-marine systems through the addition of salt, whenever this option is feasible and does not affect the survival of aquatic species being cultured.

The uppermost millimeter of the water column, the surface microlayer (SML), hosts bacterial communities (bacterioneuston) with potential metabolic adaptations to this unique physical and chemical environment. Hydrolysis and monomer incorporation by bacterioneuston and bacterioplankton communities in the estuarine system, Ria de Aveiro, was investigated and compared during a 2-year survey. The study was conducted at two contrasting sites, typifying the marine and brackish water characteristics of the estuary and with different sources, amounts and composition of organic matter. In the marine zone, bacterioneuston showed higher rates of hydrolysis and lower rates of monomer incorporation than bacterioplankton, whereas in the brackish water zone, neustonic and planktonic microbial communities showed similar activity rates. This pattern may result from the different degree of surface organic and inorganic matter enrichments, which reflect site-specific characteristics, such as hydrodynamics and sources of organic matter composition. In general, the estuarine SML environment favors polymer hydrolysis, but inhibits monomer utilization, in comparison with the subsurface layers. However, the differences between the two communities tend to decrease as autotrophic and heterotrophic activities increase in the brackish-water area.

Silicon based planar photonic molecules are shown to be effective for spectral engineering. We demonstrate optical carrier recycling, potential for modulation beyond resonator line width, and efficient signal multicasting all with small footprint structures. Article not available.

Summary Nociception is the ability to perceive potentially tissue-damaging energy to promote avoidance behavior and minimize the insult. Pain perception also aids in the repair of minor tissue injuries by limiting activity and splinting the injured tissue. Beyond this, more profound injuries, such as surgical insults, trigger a cascade of local inflammatory changes and neuronal activity that can be attenuated by analgesic pharmacotherapy. Continuous advances in the understanding of nociception and pharmacotherapeutics have resulted from the development of selective neurotransmitter ligands and the mapping of their receptor distribution. These endeavors delineate a set of primary physiologic and pathophysiologic adaptations in response to noxious stimuli. Architecturally, nociceptive pathways seem to be hard-wired. The dynamic functional changes of the system, when exposed to chronic noxious stimulation, however, betray the complex and often irreversible alterations in receptor expression that define central neuropathic pain. With the acknowledgment that nociceptive pathways can suffer these deleterious changes, preemptive therapy may be able not only to attenuate the nociceptive signal but also prevent the progression to chronic, recalcitrant neurogenic pain. Appreciation of currently available analgesics and an anticipation of those in development will allow for the judicious management of the pain patient.

We present a study on the growth of Be-doped InGaP layers lattice matched to GaAs substrates by chemical beam epitaxy. We show that the presence of the dopant affects not only electrical but the structural properties — crystal quality and morphology — as well. For samples grown at higher temperatures, a saturation of the electrical carrier concentration is observed, associated to degradation of surface morphology and crystal quality. Our results suggest that at these higher temperatures the excess of Be atoms — which are not electrically active — are incorporated as microcrystals of Be 3 P 2 which may give rise to defects in the layers. Reducing the growth temperature can alter this scenario, resulting in Be-doped InGaP layers with improved crystal quality, planar morphology and no saturation in the electrical carrier concentration for Be concentrations up to 3×10 19 cm −3 .

Aqueous solutions of alkylamines and 95% ethyl alcohol will react with the acid chloride of polyethylene-co-acrylic acid to form amides and ester, respectively. Chemical and spectroscopic evidence, as well as contact angle measurements, shows that the reactions are due to formation of acid chloride groups below the polymer's surface. A film of SOCl2-treated polyethylene-co-acrylic acid retains its reactivity to amines and alcohol even after long soaking in aqueous base. Alkylamines and ethyl alcohol readily penetrate into the polymer film where they react with interior acid chloride groups, while water and charged or large molecules do not. To explain the film's properties, a three-layer model of its morphology is proposed. Practical application of the acid chloride film to the tethering of aminoalkyl-5‘-modified oligo-DNA is demonstrated. A site-specific reaction tethers the oligo-DNA to the film exclusively via its aminoalkyl tail. The reaction occurs spontaneously when the acid chloride film is allowed...

Aspergillus niger was grown in an industrial gold mining solution containing cyano-metal complexes. Gold, silver, copper, iron and zinc were accumulated, and the major mechanism of metal uptake involved metal precipitation on the cell surface. This could be achieved by the extensive application of instrumental analyses combined to the study of the chemical composition of the solutions, before and after contact with the fungus.

Uncooled operation of long-reach high performance C-band 10 Gb/s of optical modulator modules is presented. Modules consisting of a distributed feedback laser and a chip with a monolithically integrated electroabsorption modulator and semiconductor optical amplifier based on multiquantum-well structures of both InGaAsP-InP and InGaAlAs-InP material systems are presented. Dispersion penalty of 1 dB over 94-km transmission, output power above 0 dBm, and low extinction ratio variation are demonstrated over an 80/spl deg/C temperature range. A simple analysis of the quantum confined Stark effect is employed to explain the temperature-dc bias voltage dependence.

We describe the fabrication optimization of Er-doped Al2O3 films for III-V integrated photonics. Smooth and thick films, with high refractive index and Erbium emission in the C-band spectrum (1530 nm to 1565 nm) are obtained using the co-sputtering technique. Thermal annealing at 850 °C is shown to provide the highest Photoluminescence intensity of the films. However, the onset of crystallization leads to large fluctuation in refractive index. We also show that the annealing at temperatures larger than 600 °C causes well intermixing in the laser structure. Therefore, local annealing and/or a reduction in annealing temperature may be required. Alumina waveguides are fabricated by the same technique, but the process have to be improved, as optical losses are very high.

A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry (GC×GC–ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC–ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC–ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans.

The dose-dependent variation of oxidative cellular damage imposed by UVB exposure in a representative estuarine bacterial strain, Pseudomonas sp. NT5I1.2B, was studied at different growth phases (mid-exponential, late-exponential, and stationary), growth temperatures (15 °C and 25 °C) and growth media (nutrient-rich Tryptic Soy Broth [TSB] and nutrient-poor M9). Survival and markers of oxidative damage (lipid peroxidation, protein carbonylation, DNA strand breakage, and DNA-protein cross-links) were monitored during exposure to increasing UVB doses (0-60 kJ m(-2)). Oxidative damage did not follow a clear linear dose-dependent pattern, particularly at high UVB doses (>10 kJ m(-2)), suggesting a dynamic interaction between damage induction and repair during irradiation and/or saturation of oxidative damage. Survival of stationary phase cells generally exceeded that of exponential phase cells by up to 33.5 times; the latter displayed enhanced levels of DNA-protein cross-links (up to 15.6-fold) and protein carbonylation (up to 6.0-fold). Survival of mid-exponential phase cells was generally higher at 15 °C than at 25 °C (up to 6.6-fold), which was accompanied by lower levels of DNA strand breaks (up to 4000-fold), suggesting a temperature effect on reactive oxygen species (ROS) generation and/or ROS interaction with cellular targets. Survival under medium-high UVB doses (>10 kJ m(-2)) was generally higher (up to 5.4-fold) in cells grown in TSB than in M9. These results highlight the influence of growth conditions preceding irradiation on the extent of oxidative damage induced by UVB exposure in bacteria. Acknowledgments are due to Susana Machado, Inês Baptista and Silvia F. Lopes (Department of Biology, University of Aveiro) for assistance with laboratorial work. We are indebted to the anonymous reviewers and editor for their helpful suggestions and constructive criticism. Financial support for this work was provided by CESAM (Centre for Environmental and Marine Studies, University of Aveiro) and the Portuguese Foundation for Science and Technology (FCT) in the form of a PhD grant to A.L. Santos (SFRH/BD/40160/2007) and a post-Doctoral grant to I. Henriques (SFRH/BPD/63487/2009). published

Light activation of photosensitizing dyes in presence of molecular oxygen generates highly cytotoxic reactive oxygen species leading to cell inactivation. Nucleic acids are molecular targets of this photodynamic action but not considered the main cause of cell death. The in vivo effect of the photodynamic process on the intracellular nucleic acid content of Escherichia coli and Staphylococcus warneri was evaluated herein. Two cationic porphyrins (Tetra-Py+-Me and Tri-Py+-Me-PF) were used to photoinactivate E. coli (5.0 μM; 108cells mL-1) and S. warneri (0.5 μM; 108cells mL-1) upon white light irradiation at 4.0 mW cm-2for 270 min and 40 min, respectively. Total nucleic acids were extracted from photosensitized bacteria after different times of irradiation and analyzed by agarose gel electrophoresis. The double-stranded DNA was quantified by fluorimetry and the porphyrin binding to bacteria was determined by spectrofluorimetry. E. coli was completely photoinactivated with both porphyrins (5.0 μM), whereas S. warneri was only completely inactivated by Tri-Py+-Me-PF (0.5 μM). The hierarchy of nucleic acid changes in E. coli was in the order: 23S rRNA > 16S rRNA > genomic DNA. The nucleic acids of S. warneri were extensively reduced after 5 min with Tri-Py+-Me-PF but almost unchanged with Tetra-Py+-Me after 40 min of irradiation. The amount of Tri-Py+-Me-PF bound to E. coli after washing the cells is higher than Tetra-Py+-Me and the opposite was observed for S. warneri. The binding capacity of the photosensitizers is not directly related to the PDI efficiency or nucleic acid reduction and this reduction occurs in parallel with the decrease of surviving cells. Thanks are due to Fundação para a Ciência e a Tecnologia (FCT, Portugal), European Union, QREN, FEDER and COMPETE for funding the Centre for Environmental and Marine Studies (CESAM) (project Pest-C/MAR/LA0017/2011) and the QOPNA research unit (project PEst-C/QUI/UI0062/2011). published

A theoretical approach to nonplanar wave propagation through Bragg reflector multilayer structures is presented. The theory is applied to the optical coupling and feedback in a folded cavity surface emitting laser using a 45/spl deg/ deflection mirror-epitaxial Bragg reflector arrangement. The effects of the nonplanar wave propagation on the Bragg mirror reflectivity in vertical cavity surface emitting lasers is also examined. Experimental verification of the theory is presented in a novel folded cavity surface emitting laser structure integrating a horizontal cavity InGaAs-GaAs laser grown on a structured substrate with a high reflectivity Bragg reflector. >

The purpose of this study was to explore the possible link between metals and UV-B-induced damage in bacteria. The effect of growth in the presence of enhanced concentrations of different transition metals (Co, Cu, Fe, Mn and Zn) on the UV-B sensitivity of a set of bacterial isolates was explored in terms of survival, activity and oxidative stress biomarkers (ROS generation, damage to DNA, lipid and proteins and activity of antioxidant enzymes). Metal amendment, particularly Fe, Cu and Mn, enhanced bacterial inactivation during irradiation by up to 35.8%. Amendment with Fe increased ROS generation during irradiation by 1.2-13.3%, DNA damage by 10.8-37.4% and lipid oxidative damage by 9.6-68.7%. Lipid damage during irradiation also increased after incubation with Cu and Co by up to 66.8% and 56.5% respectively. Mn amendment decreased protein carbonylation during irradiation by up to 44.2%. These results suggest a role of Fe, Co, Cu and Mn in UV-B-induced bacterial inactivation and the importance of metal homeostasis to limit the detrimental effects of ROS generated during irradiation. Acknowledgments are due to Prof. Dr. Amparo Faustino (Chemistry Department, University of Aveiro) for carefully reviewing the preliminary version of the manuscript and providing access to the spectrofluorimeter. We also thank the anonymous reviewers and editor for their helpful criticism. Financial support for this work was provided by CESAM (Centre for Environmental and Marine Studies, University of Aveiro) and the Portuguese Foundation for Science and Technology (FCT) in the form of a PhD grant to A.L. Santos (SFRH/ BD/40160/2007) and a post-Doctoral grant to I. Henriques (SFRH/BPD/ 63487/2009). published

Bacteria from the surface microlayer (bacterioneuston) and underlying waters (bacterioplankton) were isolated upon exposure to UV-B radiation, and their individual UV sensitivity in terms of CFU numbers, activity (leucine and thymidine incorporation), sole-carbon source use profiles, repair potential (light-dependent and independent), and photoadaptation potential, under different physiological conditions, was compared. Colony counts were 11.5-16.2% more reduced by UV-B exposure in bacterioplankton isolates (P

The biological effects of UV radiation of different wavelengths (UVA, UVB and UVC) were assessed in nine bacterial isolates displaying different UV sensitivities. Biological effects (survival and activity) and molecular markers of oxidative stress [DNA strand breakage (DSB), generation of reactive oxygen species (ROS), oxidative damage to proteins and lipids, and the activity of antioxidant enzymes catalase and superoxide dismutase] were quantified and statistically analyzed in order to identify the major determinants of cell inactivation under the different spectral regions. Survival and activity followed a clear wavelength dependence, being highest under UVA and lowest under UVC. The generation of ROS, as well as protein and lipid oxidation, followed the same pattern. DNA damage (DSB) showed the inverse trend. Multiple stepwise regression analysis revealed that survival under UVA, UVB and UVC wavelengths was best explained by DSB, oxidative damage to lipids, and intracellular ROS levels, respectively. The authors would like to thank the anonymous reviewers and editors who provided helpful criticism and suggestions which greatly contributed to improve the original manuscript. Acknowledgments are due to Francisco Coelho and Abel Ferreira for assistance in UV intensity measurements and to Prof. Rosário Correia (Physics Department, Universiy of Aveiro) for reviewing the manuscript. Financial support for this work was provided by CESAM (Centre for Environmental and Marine Studies, University of Aveiro) and the Portuguese Foundation for Science and Technology (FCT) in the form of a PhD grant to A. L. Santos (SFRH/BD/40160/2007) and a post-Doctoral grant to I. Henriques (SFRH/BPD/63487/2009). published

In this study the effect of organic and inorganic nanomaterials (NMs) on the structural diversity of the soil microbial community was investigated by Denaturing Gradient Gel Electrophoresis, after amplification with universal primers for the bacterial region V6–V8 of 16S rDNA. The polymers of carboxylmethyl-cellulose (CMC), of hydrophobically modified CMC (HM-CMC), and hydrophobically modified polyethylglycol (HM-PEG); the vesicles of sodium dodecyl sulphate/didodecyl dimethylammonium bromide (SDS/DDAB) and of monoolein/sodium oleate (Mo/NaO); titanium oxide (TiO 2 ), titanium silicon oxide (TiSiO 4 ), CdSe/ZnS quantum dots, gold nanorods, and Fe/Co magnetic fluid were the NMs tested. Soil samples were incubated, for a period of 30 days, after being spiked with NM suspensions previously characterized by Dynamic Light Scattering (DLS) or by an ultrahigh-resolution scanning electron microscope (SEM). The analysis of similarities (ANOSIM) of DGGE profiles showed that gold nanorods, TiO 2 , CMC, HM-CMC, HM-PEG, and SDS/DDAB have significantly affected the structural diversity of the soil bacterial community.