Export 412 results:
Sort by: Author Title Type [ Year  (Desc)]
2016
Moniz, AB, Krings B-J.  2016.  Special issue on robots and the work environment. Societies. 2016(4):31.Website
Krings, B-J.  2016.  Strategien der Individualisierung. Neue Konzepte und Befunde zur soziologischen Individualisierungsthese. , Bielefeld: transcript Abstract

Der Begriff der Individualisierung trägt in der Regel negative Konnotationen: sei es im Hinblick auf eine zunehmende Vereinzelung und Vereinsamung von Individuen oder hinsichtlich der Zunahme egoistisch anmutender Handlungen von Menschen, die das Gemeinwohl aus dem Blick verlieren. Prozesse der Individualisierung werden daher häufig als Bedrohung für die Konstituierung moderner Gesellschaften diskutiert. Diese Studie hingegen präsentiert eine neue Lesart der Individualisierung. Orientiert an Niklas Luhmanns Arbeiten und gestützt auf Ergebnisse einer empirischen Studie legt Bettina-Johanna Krings eine soziologische Betrachtung vor, die die Aufforderung zur Individualisierung als eine notwendige Herausforderung in modernen Gesellschaften interpretiert.

Santos, L, Silveira CM, Elangovan E, Neto JP, Nunes D, Pereira L, Martins R, Viegas J, Moura JJG, Todorovic S, Almeida MG, Fortunato EM.  2016.  Synthesis of WO3 nanoparticles for biosensing applications. Sensors and Actuators B: Chemical. 223:186-194.
Ma, Z, Zhang B, da Silva FGMC, Mendo AS, Silva J, Baptista PV, Fernandes AR, Pombeiro AJL.  2016.  Synthesis, Characterization, Thermal Properties and Antiproliferative Potential of Copper(II) 4′-phenyl-terpyridine Compounds. Dalton Transations. (12) AbstractWebsite

Reactions between 4′-phenyl-terpyridine (L) and several Cu(II) salts (p-toluenesulfonate, benzoate and o-, m- or p-hydroxybenzoate) led to the formation of [Cu(p-SO3C6H4CH3)L(H2O)2](p-SO3C6H4CH3) (1), [Cu(OCOPh)2L] (2), [Cu(o-OCOC6H4OH)2L] (3), [Cu(m-OCOC6H4OH)2L]·MeOH (4·MeOH) and [Cu(p-OCOC6H4OH)2L]·2H2O (5·2H2O), which were characterized by elemental and TG-DTA analyses, ESI-MS, IR spectroscopy and single crystal X-ray diffraction, as well as by conductivimetry. In all structures the Cu atoms present N3O3 octahedral coordination geometries, which, in 2–5, are highly distorted as a result of the chelating-bidentate mode of one of the carboxylate ligands. Intermolecular π⋯π stacking interactions could also be found in 2–5 (in the 3.569–3.651 Å range and involving solely the pyridyl rings). Medium–strong hydrogen bond interactions lead to infinite 1D chains (in 1 and 4) and to an infinite 2D network (in 5). Compounds 1 and 4 show high in vitro cytotoxicity towards HCT116 colorectal carcinoma and HepG2 hepatocellular carcinoma cell lines. The antiproliferative potential of compound 1 is due to an increase of the apoptotic process that was confirmed by Hoechst staining, flow cytometry and RT-qPCR. All compounds able to non-covalently intercalate the DNA helix and induce in vitro pDNA double-strand breaks in the absence of H2O2. Concerning compound 1, the hydroxyl radical and singlet oxygen do not appear to be involved in the pDNA cleavage process and the fact that this cleavage also occurs in the absence of molecular oxygen points to a hydrolytic mechanism of cleavage.

Terao, M, Romão MJ, Leimkühler S, Bolis M, Fratelli M, Coelho C, Santos-Silva T, Garattini E.  2016.  Structure and function of mammalian aldehyde oxidases. Archives of Toxicology. 90:753–780., Number 4 AbstractWebsite

Mammalian aldehyde oxidases (AOXs; EC1.2.3.1) are a group of conserved proteins belonging to the family of molybdo-flavoenzymes along with the structurally related xanthine dehydrogenase enzyme. AOXs are characterized by broad substrate specificity, oxidizing not only aromatic and aliphatic aldehydes into the corresponding carboxylic acids, but also hydroxylating a series of heteroaromatic rings. The number of AOX isoenzymes expressed in different vertebrate species is variable. The two extremes are represented by humans, which express a single enzyme (AOX1) in many organs and mice or rats which are characterized by tissue-specific expression of four isoforms (AOX1, AOX2, AOX3, and AOX4). In vertebrates each AOX isoenzyme is the product of a distinct gene consisting of 35 highly conserved exons. The extant species-specific complement of AOX isoenzymes is the result of a complex evolutionary process consisting of a first phase characterized by a series of asynchronous gene duplications and a second phase where the pseudogenization and gene deletion events prevail. In the last few years remarkable advances in the elucidation of the structural characteristics and the catalytic mechanisms of mammalian AOXs have been made thanks to the successful crystallization of human AOX1 and mouse AOX3. Much less is known about the physiological function and physiological substrates of human AOX1 and other mammalian AOX isoenzymes, although the importance of these proteins in xenobiotic metabolism is fairly well established and their relevance in drug development is increasing. This review article provides an overview and a discussion of the current knowledge on mammalian AOX.

Ma, Z, Zhang B, {Guedes da Silva} F{MC }, Silva J, Mendo {AS}, Baptista {PV}, Fernandes {AR}, Pombeiro {AJL }.  2016.  Synthesis, characterization, thermal properties and antiproliferative potential of copper(II) 4 '-phenylterpyridine compounds. Dalton Transactions. 45:5339–5355., Number 12: RSC - Royal Society of Chemistry Abstract

Reactions between 4'-phenyl-terpyridine (L) and several Cu(II) salts (p-toluenesulfonate, benzoate and o-, m-or p-hydroxybenzoate) led to the formation of [Cu(p-SO3C6H4CH3)L(H2O)(2)](p-SO3C6H4CH3) (1), [Cu(OCOPh)(2)L] (2), [Cu(o-OCOC6H4OH)(2)L] (3), [Cu(m-OCOC6H4OH)(2)L]center dot MeOH (4 center dot MeOH) and [Cu(pOCOC(6)H(4)OH)(2)L]center dot 2H(2)O (5 center dot 2H2O), which were characterized by elemental and TG-DTA analyses, ESI-MS, IR spectroscopy and single crystal X-ray diffraction, as well as by conductivimetry. In all structures the Cu atoms present N3O3 octahedral coordination geometries, which, in 2-5, are highly distorted as a result of the chelating-bidentate mode of one of the carboxylate ligands. Intermolecular pi...pi stacking interactions could also be found in 2-5 (in the 3.569-3.651 angstrom range and involving solely the pyridyl rings). Mediumstrong hydrogen bond interactions lead to infinite 1D chains (in 1 and 4) and to an infinite 2D network (in 5). Compounds 1 and 4 show high in vitro cytotoxicity towards HCT116 colorectal carcinoma and HepG2 hepatocellular carcinoma cell lines. The antiproliferative potential of compound 1 is due to an increase of the apoptotic process that was confirmed by Hoechst staining, flow cytometry and RT-qPCR. All compounds able to non-covalently intercalate the DNA helix and induce in vitro pDNA double-strand breaks in the absence of H2O2. Concerning compound 1, the hydroxyl radical and singlet oxygen do not appear to be involved in the pDNA cleavage process and the fact that this cleavage also occurs in the absence of molecular oxygen points to a hydrolytic mechanism of cleavage.

2015
Veigas, B, Portugal C, Valério R, Fortunato E, Crespo {JG }, Baptista P.  2015.  Scalable approach for the production of functional DNA based gold nanoprobes, oct. Journal of Membrane Science. 492:528–535.: Elsevier Abstract

Nanoparticle based systems, in particular gold nanoparticles (AuNPs), provide for simple calorimetric detection of molecular biomarkers, such as DNA, RNA. These systems rely on the functionalization of AuNPs with ssDNA oligonucleotides requiring strenuous laboratory centrifugation steps not compatible with industrial scale up. Here, we demonstrate the potential of dia-ultrafiltration for purification of Au-nanoprobes. We show that dia-ultrafiltration can be regarded as better alternative to centrifugation, allowing for a less intensive sample manipulation, easier transposable to the industrial scale. The purification of AuNPs was performed by dia-ultrafiltration using membranes of regenerated cellulose with a nominal molecular weight cut-off (MWCO) of 10 kDa and a processing strategy which combined subsequent AuNPs cleaning and concentration steps. instead of the permeation flux decline typically found in ultrafiltration processes operated under concentration modes, purification of Au-nanoprobes by dia-ultrafiltration was followed by a subtle increase of the permeation fluxes. This effect was ascribed to improved external mass transfer conditions near the membrane surface, prompted by the decrease of the overall solute concentration in the retentate over the process Lime. This strategy allowed for the total retention of the AuNPS, yielding nanoprobes capable of higher signal to noise ratios. Proof-of-concept was directed at the synthesis of Au-nanoprobes for identification of members of the Mycobacterium tuberculosis complex that cause tuberculosis in humans. (C) 2015 Elsevier B.V. All rights reserved.

McCully, M, Hernandez Y, Conde J, Baptista {PMRV}, {de la Fuente} {JM }, Hursthouse A, Stirling D, Berry {CC }.  2015.  Significance of the balance between intracellular glutathione and polyethylene glycol for successful release of small interfering RNA from gold nanoparticles, oct. Nano Research. 8:3281–3292., Number 10: Tsinghua University Press | Springer Abstract

The therapeutic promise of small interfering RNAs (siRNAs) for specific gene silencing is dependent on the successful delivery of functional siRNAs to the cytoplasm. Their conjugation to an established delivery platform, such as gold nanoparticles, offers tremendous potential for treating diseases and advancing our understanding of cellular processes. Their success or failure is dependent on both the uptake of the nanoparticles into the cells and subsequent intracellular release of the functional siRNA. In this study, utilizing gold nanoparticle siRNA-mediated delivery against C-MYC, we aimed to determine if we could achieve knockdown in a cancer cell line with low levels of intracellular glutathione, and determine the influence, if any, of polyethylene glycol (PEG) ligand density on knockdown, with a view to determining the optimal nanoparticle design to achieve C-MYC knockdown. We demonstrate that, regardless of the PEG density, knockdown in cells with relatively low glutathione levels can be achieved, as well as the possible effect of steric hindrance of PEG on the availability of the siRNA for cleavage in the intracellular environment. Gold nanoparticle uptake was demonstrated via transmission electron microscopy and mass spectroscopy, while knockdown was determined at the protein and physiological levels (cells in S-phase) by in-cell westerns and BrdU incorporation, respectively.

Bernacka-Wojcik, I, Águas H, Carlos {FF}, Lopes P, Wojcik {PJ}, Costa {MN}, Veigas B, Igreja R, Fortunato E, Baptista P, Martins R.  2015.  Single Nucleotide Polymorphism Detection Using Gold Nanoprobes and Bio-Microfluidic Platform With Embedded Microlenses, jun. Biotechnology and Bioengineering. 112:1210–1219., Number 6: Wiley-Blackwell Abstract

The use of microfluidics platforms combined with the optimal optical properties of gold nanopartides has found plenty of application in molecular biosensing. This paper describes a biotnicrofluidic platform coupled to a non-cross-linking colorimetric gold nanoprobe assay to detect a single nucleotide polymorphism associated with increased risk of obesity fat-mass and obesity-associated (FTO) rs9939609 (Carlos et al., 2014). The system enabled significant discrimination between positive and negative assays using a target DNA concentration of 5 ng/mu l below the limit of detection of the conventionally used microplate reader (i.e., 15 ng/mu l) with 10 times lower solution volume (i.e., 3 mu l.). A set of optimization of our previously reported bio-microfluidic platform (Bemacka-Wojcik et al., 2013) resulted in a 160% improvement of colorimetric analysis results. Incorporation of planar microlenses increased 6 times signal-to-loss ratio reaching the output optical fiber improving by 34% the colorimetric analysis of gold nanopartides, while the implementation of an optoelectronic acquisition system yielded increased accuracy and reduced noise. The microfluidic chip was also integrated with a miniature fiber spectrometer to analyze the assays' cobrimetric changes and also the LEDs transmission spectra when illuminating through various solutions. Furthermore, by coupling an optical micmscope to a digital camera with a long exposure time (30s), we could visualise the different scatter intensities of gold nanoparticles within channels following salt addition. These intensities correlate well to the expected difference in aggregation between FTO positive (none to small aggregates) and negative samples (large aggregates). (C) 2015 Wiley Periodicals, Inc.

Pikramenou, Z, Weinstein J, Pan Q, Lewis F, Bassani DM, Wurthner F, Moucheron C, Slota M, Diaz-Moscoso A, Karlsson J, Basilio N, Adams D, Scandola F, Bohne C, Lemon C, Campagna S, Rohacova J, Ohashi K, Plotz PA, Monti F, Kelly JM, Keane P, Gibson E, Lemercier G, Ruggi A, Cucinotta F, Gust D, Bradberry S, Vos J, Pistolis G, Mauro M, Tuite E, De Cola L, Ceroni P, Maneiro M, Galoppini E, Gunnlaugsson T.  2015.  Self-organization of photo-active nanostructures: general discussion, 2015. Faraday Discussions. 185:529-548. AbstractWebsite
n/a
Diniz, AM, Basilio N, Cruz H, Pina F, Parola AJ.  2015.  Spatiotemporal control over the co-conformational switching in pH-responsive flavylium-based multistate pseudorotaxanes, 2015. Faraday Discussions. 185:361-379. AbstractWebsite
n/a
Coelho, C, Romao MJ.  2015.  Structural and mechanistic insights on nitrate reductases, 2015. Protein Science. 24(12):1901-1911. AbstractWebsite

Nitrate reductases (NR) belong to the DMSO reductase family of Mo-containing enzymes and perform key roles in the metabolism of the nitrogen cycle, reducing nitrate to nitrite. Due to variable cell location, structure and function, they have been divided into periplasmic (Nap), cytoplasmic, and membrane-bound (Nar) nitrate reductases. The first crystal structure obtained for a NR was that of the monomeric NapA from Desulfovibrio desulfuricans in 1999. Since then several new crystal structures were solved providing novel insights that led to the revision of the commonly accepted reaction mechanism for periplasmic nitrate reductases. The two crystal structures available for the NarGHI protein are from the same organism (Escherichia coli) and the combination with electrochemical and spectroscopic studies also lead to the proposal of a reaction mechanism for this group of enzymes. Here we present an overview on the current advances in structural and functional aspects of bacterial nitrate reductases, focusing on the mechanistic implications drawn from the crystallographic data.

Coelho, C, Foti A, Hartmann T, Santos-Silva T, Leimk S, Rom MJ.  2015.  Structural insights into xenobiotic and inhibitor binding to human aldehyde oxidase, 2015. Nat Chem Biol. 11(10):779-83.Website
Zhao, Y, He L, Tang N, Qin S, Tao GH, Liang FX.  2015.  Structures and Properties of Luminescent Pentanitratoeuropate(III) Ionic Liquids, 2015. European Journal of Inorganic Chemistry. (3):542-551. AbstractWebsite
n/a
Jordao, N, Cruz H, Branco A, Pinheiro C, Pina F, Branco LC.  2015.  Switchable electrochromic devices based on disubstituted bipyridinium derivatives, 2015. Rsc Advances. 5(35):27867-27873. AbstractWebsite
n/a
Silveira, CM, Quintas PO, Moura I, Moura JJG, Hildebrandt P, Almeida MG, Todorovic S.  2015.  SERR spectroelectrochemical study of cytochrome cd1 nitrite reductase co-immobilized with physiological redox partner cytochrome c552 on biocompatible metal electrodes. Plos One. 10:e0129940.
Contreras, J, Tornero J, Ferreira I, Martins R, Gomes L, Fortunato E.  2015.  Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays. Sensors. 15(12):29938-29949. Abstract

A MATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array.

Ferreira, M, Loureiro J, Nogueira A, Rodrigues A, Martins R, Ferreira I.  2015.  SnO2 thin Film Oxides Produced by rf Sputtering for Transparent Thermoelectric Devices. Mater. Today-Proc. 2(2):647-653. AbstractWebsite

The combination of high transparency and good thermoelectric properties of SnO2 can open new field of applications for the thin film thermoelectric materials. Here we report on SnO2 thin films with transmittance above 90%, resistivity bellow 10-3 Ωm and a Power Factor around 10-4 W/m.K2, for a Seebeck of -255 μV/K, at room temperature. The effect of film thickness and post-deposition annealing on the thermoelectric properties were analysed. The performances of a single layer thermoelectric device are also presented.

Neagu, E, Lança MC, Dias C, Marat-Mendes J.  2015.  Space charge and dipolar charge contribution at polar polymers polarization. IEEE Transactions on Dielectrics and Electrical Insulation. 22(3):1419-1426. AbstractWebsite

The thermally stimulated discharge current, the final thermally stimulated discharge current, DC conductivity and the final thermally stimulated discharge current with partially blocking electrode measures were used to analyze electrical behavior of Nylon 11. The objective was to discriminate between dipole related effects and space charge related effects. The space charge effects are dominant in the temperature range from room temperature to 170 °C. By using a Teflon-FEP partially blocking electrode, the space charge injected in the sample is diminished and the effects related to dipole movement can be observed. Beside the two known relaxations for Nylon 11, one associated with the glass transition around 60 °C and a second one associated with a molecular motion in the rigid-amorphous phase at 96 °C, a weak relaxation was observed around 168 °C. The peak around 96 °C is quite broad been composed of two narrow peaks. The final thermally stimulated discharge current method allows a better selection of the experimental conditions for sample charging (polarization) to have only a partial overlap between the nearby peaks. The peak's maximum current and temperature are dependent on the ratio between the charging and discharging time and temperature given a possibility to discriminate between dipolar and space charge effects. A pyroelectric current changes sign around 140 °C indicating that the amidegroup dipoles are frozen in opposite directions when the sample temperature is below 140 °C (amorphous and rigid-amorphous phase) or above (crystalline phase). The conductivity is controlled by the competition between n(E,T) and μ(E,T) indicating a space charge controlled conductivity mechanism.

Reed, P, Atilano ML, Alves R, Hoiczyk E, Sher X, Reichmann NT, Pereira PM, Roemer T, Filipe SR, Pereira-Leal JB, Ligoxygakis P, Pinho MG.  2015.  Staphylococcus aureus survives with a minimal peptidoglycan synthesis machinery but sacrifices virulence and antibiotic resistance. PLoS Pathogens. 11:e1004891.
Dantas, JM, Campelo LM, Duke NEC, Salgueiro CA, Pokkuluri PR.  2015.  The structure of PccH from Geobacter sulfurreducens: a novel low reduction potential monoheme cytochrome essential for accepting electrons from an electrode. FEBS J. 282(11):2215-2231. AbstractWebsite

The structure of cytochrome c (GSU3274) designated as PccH from Geobacter sulfurreducens was determined at a resolution of 2.0 Å. PccH is a small (15 kDa) cytochrome containing one c-type heme, found to be essential for the growth of G. sulfurreducens with respect to accepting electrons from graphite electrodes poised at -300 mV versus standard hydrogen electrode. with fumarate as the terminal electron acceptor. The structure of PccH is unique among the monoheme cytochromes described to date. The structural fold of PccH can be described as forming two lobes with the heme sandwiched in a cleft between the two lobes. In addition, PccH has a low reduction potential of -24 mV at pH 7, which is unusual for monoheme cytochromes. Based on difference in structure, together with sequence phylogenetic analysis, we propose that PccH can be regarded as a first characterized example of a new subclass of class I monoheme cytochromes. The low reduction potential of PccH may enable the protein to be redox active at the typically negative potential ranges encountered by G. sulfurreducens. Because PccH is predicted to be located in the periplasm of this bacterium, it could not be involved in the first step of accepting electrons from the electrode but is very likely involved in the downstream electron transport events in the periplasm.

Silva, JA, Vale TM, Dias RJ, Paulino H, Lourenço JM.  2015.  Supporting Multiple Data Replication Models in Distributed Transactional Memory. Proceedings of the 2015 International Conference on Distributed Computing and Networking. , Goa, India: ACM Abstract2015-icdcn.pdf

n/a

Carvalho, LCR, Ribeiro D, Seixas RSGR, Silva AMS, Nave M, Martins AC, Erhardt S, Fernandes E, Cabrita EJ, Marques MMB.  2015.  Synthesis and evaluation of new benzimidazole-based COX inhibitors: a naproxen-like interaction detected by STD-NMR. RSC Advances. 5:49098-49109., Number {61} Abstract

Non-steroidal anti-inflammatory drugs exert their pharmacological activity through inhibition of cyclooxygenase 1 and 2 (COX-1 and COX-2). Recent research suggests that a balanced inhibition of both COX-1 and COX-2 is the key to reduce the side-effects exhibited by COX inhibitors. We developed new benzimidazole-based compounds that showed a balanced COX inhibition, supported by molecular docking screening. The human whole blood assays demonstrated that the ester derivatives were potent inhibitors. Competitive saturation transfer difference (STD)-NMR experiments, in the presence of COX-2, using naproxen and diclofenac demonstrated that ester derivatives do not compete with diclofenac for the same binding site, but compete with the allosteric inhibitor naproxen. Combination of NMR spectroscopy with molecular docking has permitted us to detect a new naproxen-like inhibitor, which could be used for future drug development.

Carvalho, A, Sebastiao PJ, Fonseca I, Matos J, Goncalves MC.  2015.  Silica and silica organically modified nanoparticles: Water dynamics in complex systems. Microporous and Mesoporous Materials. 217:102-108. AbstractWebsite

Four silica-based porous nanosystems were synthesized with different organic substitutes and the molecular dynamics of water in these constrained environment was investigated. The nanosystems were silica and three organic modified silica nanoparticles (NP) with diameters in the range 80-300 nm with different porous dimensions, surface areas, and surface properties (e.g. hydrophilicity/hydrophobicity). Molecular dynamics was studied by pulsed field gradient NMR and by proton spin-lattice relaxation in a broad range of Larmor frequencies. A coherent analysis of the diffusion coefficients and spin-lattice relaxation data is presented taking into account a relaxation model associated to water molecular dynamics in close contact with NP surfaces. From our results it was possible to access the details of the water molecular movements in the nanosystems and to single out two water populations presenting distinct molecular dynamics. Characteristic distances for water rotations mediated by translational diffusion were estimated in consistency with the NP's dimensions and pores sizes obtained by TEM and BET experimental techniques. This knowledge has both fundamental and practical relevance since these NP have applications in nanomedicine, not only in therapy but also in diagnostic procedures and more recently in theranostic. (C) 2015 Elsevier Inc. All rights reserved.

Safari, L, Amaro P, Santos JP, Fratini F.  2015.  Spin effects probed by Rayleigh X-ray scattering off hydrogenic ions. Radiation Physics and Chemistry. AbstractWebsite

We study the polarization characteristics of X-ray photons scattered by hydrogenic atoms, based on the Dirac equation and second-order perturbation theory. The.