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Cobalt-cemented carbide micro-end mills were coated with diamond grown by chemical vapor deposition (CVD), with the purpose of micro-machining cemented carbides. The diamond coatings were designed with a multilayer architecture, alternating between sub-microcrystalline and nanocrystalline diamond layers. The structure of the coatings was studied by transmission electron microscopy. High adhesion to the chemically pre-treated WC-7Co tool substrates was observed by Rockwell C indentation, with the diamond coatings withstanding a critical load of 1250 N. The coated tools were tested for micro-end-milling of WC-15Co under air-cooling conditions, being able to cut more than 6500 m over a period of 120 min, after which a flank wear of 47.8 μm was attained. The machining performance and wear behavior of the micro-cutters was studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy. Crystallographic analysis through cross-sectional selected area electron diffraction patterns, along with characterization in dark-field and HRTEM modes, provided a possible correlation between interfacial stress relaxation and wear properties of the coatings. Overall, this work demonstrates that high adhesion of diamond coatings can be achieved by proper combination of chemical attack and coating architecture. By preventing catastrophic delamination, multilayer CVD diamond coatings are central towards the enhancement of the wear properties and mechanical robustness of carbide tools used for micro-machining of ultra-hard materials.
Eduardo Silva; Sérgio Pratas; Miguel Neto; Cristina Fernandes; Daniel Figueiredo; Rui Silva. Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide. Materials 2021, 14, 3333 .
AMA StyleEduardo Silva, Sérgio Pratas, Miguel Neto, Cristina Fernandes, Daniel Figueiredo, Rui Silva. Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide. Materials. 2021; 14 (12):3333.
Chicago/Turabian StyleEduardo Silva; Sérgio Pratas; Miguel Neto; Cristina Fernandes; Daniel Figueiredo; Rui Silva. 2021. "Multilayer Diamond Coatings Applied to Micro-End-Milling of Cemented Carbide." Materials 14, no. 12: 3333.
Carbon nanostructures-silica aerogel composites were synthesized and characterized to assess the effect of carbon nanotubes (CNTs) or graphene oxide (GO) on the silica aerogel properties. The sol-gel chemistry was based on methyltrimethoxysilane (MTMS) and 3-aminopropyltrimethoxysilane (APTMS) as silica precursor system, with varying amounts of APTMS (0–20% mol of Si). APTMS significantly impacted the materials' physical properties. The chemistry and microstructure were investigated by FTIR, NMR, TEM, SEM, SAXS and BET. The addition of CNTs induced the growth of the silica matrix around them; thus, an elongated shape was observed in the silica structural units. APTMS and CNTs have a synergistic effect on the mechanical properties, increasing the Young's modulus up to 14 MPa. Small amounts of carbon materials (∼1 wt%) in the MTMS-matrix improved its thermal insulation property, particularly for temperatures above 50 °C. In terms of electrochemical properties, the carbon nanostructures lead to higher specific capacitances and a reduction in resistance. The characterizations here performed allowed a better understanding of the interactions between the silica and carbon phases. The possibility to obtain materials with tailored properties demonstrates their application potential in several areas, such as thermal insulation and energy storage.
Alyne Lamy-Mendes; Wim J. Malfait; Amin Sadeghpour; Ana V. Girão; Rui F. Silva; Luísa Durães. Influence of 1D and 2D carbon nanostructures in silica-based aerogels. Carbon 2021, 180, 146 -162.
AMA StyleAlyne Lamy-Mendes, Wim J. Malfait, Amin Sadeghpour, Ana V. Girão, Rui F. Silva, Luísa Durães. Influence of 1D and 2D carbon nanostructures in silica-based aerogels. Carbon. 2021; 180 ():146-162.
Chicago/Turabian StyleAlyne Lamy-Mendes; Wim J. Malfait; Amin Sadeghpour; Ana V. Girão; Rui F. Silva; Luísa Durães. 2021. "Influence of 1D and 2D carbon nanostructures in silica-based aerogels." Carbon 180, no. : 146-162.
Poly (methyl methacrylate) (PMMA) is a thermoplastic synthetic polymer, which displays superior characteristics such as transparency, good tensile strength, and processability. Its performance can be improved by surface engineering via the use of functionalized thin film coatings, resulting in its versatility across a host of applications including, energy harvesting, dielectric layers and water purification. Modification of the PMMA surface can be achieved by atomic layer deposition (ALD), a vapor-phase, chemical deposition technique, which permits atomic-level control. However, PMMA presents a challenge for ALD due to its lack of active surface sites, necessary for gas precursor reaction, nucleation, and subsequent growth. The purpose of this review is to discuss the research related to the employment of PMMA as either a substrate, support, or masking layer over a range of ALD thin film growth techniques, namely, thermal, plasma-enhanced, and area-selective atomic layer deposition. It also highlights applications in the selected fields of flexible electronics, biomaterials, sensing, and photocatalysis, and underscores relevant characterization techniques. Further, it concludes with a prospective view of the role of ALD in PMMA processing.
Marta Forte; Ricardo Silva; Carlos Tavares; Rui Silva. Is Poly(methyl methacrylate) (PMMA) a Suitable Substrate for ALD?: A Review. Polymers 2021, 13, 1346 .
AMA StyleMarta Forte, Ricardo Silva, Carlos Tavares, Rui Silva. Is Poly(methyl methacrylate) (PMMA) a Suitable Substrate for ALD?: A Review. Polymers. 2021; 13 (8):1346.
Chicago/Turabian StyleMarta Forte; Ricardo Silva; Carlos Tavares; Rui Silva. 2021. "Is Poly(methyl methacrylate) (PMMA) a Suitable Substrate for ALD?: A Review." Polymers 13, no. 8: 1346.
Molybdenum oxide thin films were deposited on stiff and flexible substrates by reactive DC magnetron sputtering. Two sets of samples were prepared. The first with different O2/Ar flow rate ratios and the second, fixing the oxygen content, with different time of deposition. As the O2/Ar flow rate ratio varies from 0 up to 0.56, a threshold was found, ranging from crystalline to amorphous nature, and from a nontransparent appearance with metallic-like electrical conductivity to transparent and dielectric behaviour. From the second set, all transparent, the MoOx films present a compact/dense and featureless morphology with thickness from 190 up to 910 nm, depending on the time of deposition. Their structure was corroborated by XPS and Rutherford Backscattering Spectrometry (RBS) and density measurements were performed by RBS and X-ray reflectivity (XRR), revealing a value of 2.4 g/cm3. The surface roughness is in the order of a few nanometers and the maxima optical transmission, in the visible range, is around 89%. Electrochemical cyclic voltammograms showed noticeable color reversibility and reproducibility on the flexible substrates opening new framework possibilities for new electrochomic devices.
Alice Marciel; Manuel Graça; Alexandre Bastos; Luiz Pereira; Jakka Suresh Kumar; Joel Borges; Filipe Vaz; Marco Peres; Sergio Magalhães; Katharina Lorenz; Rui Silva. Molybdenum Oxide Thin Films Grown on Flexible ITO-Coated PET Substrates. Materials 2021, 14, 821 .
AMA StyleAlice Marciel, Manuel Graça, Alexandre Bastos, Luiz Pereira, Jakka Suresh Kumar, Joel Borges, Filipe Vaz, Marco Peres, Sergio Magalhães, Katharina Lorenz, Rui Silva. Molybdenum Oxide Thin Films Grown on Flexible ITO-Coated PET Substrates. Materials. 2021; 14 (4):821.
Chicago/Turabian StyleAlice Marciel; Manuel Graça; Alexandre Bastos; Luiz Pereira; Jakka Suresh Kumar; Joel Borges; Filipe Vaz; Marco Peres; Sergio Magalhães; Katharina Lorenz; Rui Silva. 2021. "Molybdenum Oxide Thin Films Grown on Flexible ITO-Coated PET Substrates." Materials 14, no. 4: 821.
Working in concert, diamond layers and high-κ films impart opportunities for high performance MOS devices. Optimization hinges on their interfacial quality inciting investigation into diamond surface terminations and ALD parameters to ensure success.
Aneeta Jaggernauth; Joana C. Mendes; Rui F. Silva. Atomic layer deposition of high-κ layers on polycrystalline diamond for MOS devices: a review. Journal of Materials Chemistry C 2020, 8, 13127 -13153.
AMA StyleAneeta Jaggernauth, Joana C. Mendes, Rui F. Silva. Atomic layer deposition of high-κ layers on polycrystalline diamond for MOS devices: a review. Journal of Materials Chemistry C. 2020; 8 (38):13127-13153.
Chicago/Turabian StyleAneeta Jaggernauth; Joana C. Mendes; Rui F. Silva. 2020. "Atomic layer deposition of high-κ layers on polycrystalline diamond for MOS devices: a review." Journal of Materials Chemistry C 8, no. 38: 13127-13153.
High dielectric constant (high-κ) thin films are ubiquitous in research as they impart enhanced properties to microelectronic applications. Novel combinations for coupling high-κ and ultra-wide band gap semiconductors are being investigated for niche applications, dependent on the environmental conditions for device operation. Typically, high-κ films such as alumina are deposited by atomic layer deposition (ALD), a technique heavily dependent on surface chemistry. This work investigates the effect of plasma surface functionalization of boron doped diamond (BDD) semiconducting films on interface quality with top-layers of ALD alumina (AlO) films, by analyzing its susceptibility to deformation; being particularly vital for electronics subjected to physically demanding environments. Alumina thin films were deposited unto as-grown (AlO-H-BDD) and O2 plasma treated (AlO-O-BDD) polycrystalline BDD. XPS analysis performed on plasma exposed BDD films, prior to AlO deposition, demonstrated a 3% increase in O surface ligands compared to the as-grown surface. Nanoindentation analysis demonstrated plastic deformation within the alumina layer for AlO-O-BDD, for the tested loads, whereas AlO-H-BDD experienced film delamination and deformation beyond the alumina-BDD interface. TEM analysis revealed that delamination was most likely due to low cohesive strength of alumina near the interface, explained by fewer –OH and –CO (ether) BDD surface ligands on H-BDD.
Aneeta Jaggernauth; Rui Silva; M.A. Neto; F.J. Oliveira; I.K. Bdikin; M.P. Alegre; M. Gutiérrez; D. Araújo; Joana Catarina Mendes. Interfacial integrity enhancement of atomic layer deposited alumina on boron doped diamond by surface plasma functionalization. Surface and Coatings Technology 2020, 397, 125991 .
AMA StyleAneeta Jaggernauth, Rui Silva, M.A. Neto, F.J. Oliveira, I.K. Bdikin, M.P. Alegre, M. Gutiérrez, D. Araújo, Joana Catarina Mendes. Interfacial integrity enhancement of atomic layer deposited alumina on boron doped diamond by surface plasma functionalization. Surface and Coatings Technology. 2020; 397 ():125991.
Chicago/Turabian StyleAneeta Jaggernauth; Rui Silva; M.A. Neto; F.J. Oliveira; I.K. Bdikin; M.P. Alegre; M. Gutiérrez; D. Araújo; Joana Catarina Mendes. 2020. "Interfacial integrity enhancement of atomic layer deposited alumina on boron doped diamond by surface plasma functionalization." Surface and Coatings Technology 397, no. : 125991.
Crystalline Eu3+-2-aminoterephthalic acid thin (ca. 22 µm) films have been prepared by Atomic/Molecular Layer Deposition (ALD/MLD) on Si/SiO2 substrates. The β-diketonate complex precursor europium(III)-tris-(2,2,6,6-tetramethyl-3,5-heptanedionate, Eu(thd)3, was reacted with 2-aminoterephthalic acid, NH2TA. X-ray diffraction indicates the films deposited at 180 °C exhibit the structure of UiO-66, a Zr-bearing metal organic framework. Scanning electron microscopy and atomic force microscopy show that the prepared films are very smooth and uniform, essentially defect-free, with a surface topography comprising evenly distributed hills without sharp edges, well adherent to the substrate. Attenuated total reflectance fourier transform infrared witnesses the presence of the organic ligand in the film and its coordination to the metal. X-ray photoelectron spectroscopy confirms the trivalent Eu oxidation state. Due to their thermal stability, fair volatility and facile synthesis, β-diketonate complexes have been shown to be suitable ALD precursors for preparing high-quality lanthanide organic framework thin films, enabling a single-step gas phase method for the synthesis of luminescent films.
Ricardo Silva; L.D. Carlos; J. Rocha. Luminescent thin films of Eu-bearing UiO-66 metal organic framework prepared by ALD/MLD. Applied Surface Science 2020, 527, 146603 .
AMA StyleRicardo Silva, L.D. Carlos, J. Rocha. Luminescent thin films of Eu-bearing UiO-66 metal organic framework prepared by ALD/MLD. Applied Surface Science. 2020; 527 ():146603.
Chicago/Turabian StyleRicardo Silva; L.D. Carlos; J. Rocha. 2020. "Luminescent thin films of Eu-bearing UiO-66 metal organic framework prepared by ALD/MLD." Applied Surface Science 527, no. : 146603.
Inês E. Oliveira; Ricardo M. Silva; Ana V. Girão; Joaquim L. Faria; Cláudia G. Silva; Rui F. Silva. Facile Preparation of ZnO/CNTs Nanocomposites via ALD for Photocatalysis Applications. European Journal of Inorganic Chemistry 2020, 2020, 1743 -1750.
AMA StyleInês E. Oliveira, Ricardo M. Silva, Ana V. Girão, Joaquim L. Faria, Cláudia G. Silva, Rui F. Silva. Facile Preparation of ZnO/CNTs Nanocomposites via ALD for Photocatalysis Applications. European Journal of Inorganic Chemistry. 2020; 2020 (18):1743-1750.
Chicago/Turabian StyleInês E. Oliveira; Ricardo M. Silva; Ana V. Girão; Joaquim L. Faria; Cláudia G. Silva; Rui F. Silva. 2020. "Facile Preparation of ZnO/CNTs Nanocomposites via ALD for Photocatalysis Applications." European Journal of Inorganic Chemistry 2020, no. 18: 1743-1750.
In this work, a novel approach to synthesise zinc oxide (ZnO) directly on flexible copper substrates is proposed. The produced samples show a foam-like morphology made of agglomerates of small ZnO particles when processed at laser energy density of 18.0 J/cm2. On the other hand, the samples processed at higher beam energy density, i.e. 33.2 J/cm2, resulted in a more granular morphology, with some ZnO particles dispersed over the sample’s surface. Raman spectroscopy measurements demonstrated that this method resulted in the formation of wurtzite-ZnO crystalline phase in all samples. Room temperature photoluminescence spectroscopy analysis revealed the presence of a broad visible band in the orange-red region dominating the spectra, with a small contribution from the near band edge emission in the UV spectral region. Decreasing the beam energy fluence from 33.2 to 18.0 J/cm2 resulted in samples with higher overall visible band intensity, in line with what was observed for their crystalline quality. Moreover, the shift of the broad band maxima towards longer wavelengths could be an indication of the possibility of tuning the visible emission according to the chosen laser processing conditions.
Guilherme Gaspar; Joana Rodrigues; António J.S. Fernandes; Maria R. Soares; Teresa Monteiro; Rui F. Silva; Florinda Costa. Nd:YAG laser scribed zinc oxide on semi-flexible copper foils. Materials Letters: X 2020, 5, 100038 .
AMA StyleGuilherme Gaspar, Joana Rodrigues, António J.S. Fernandes, Maria R. Soares, Teresa Monteiro, Rui F. Silva, Florinda Costa. Nd:YAG laser scribed zinc oxide on semi-flexible copper foils. Materials Letters: X. 2020; 5 ():100038.
Chicago/Turabian StyleGuilherme Gaspar; Joana Rodrigues; António J.S. Fernandes; Maria R. Soares; Teresa Monteiro; Rui F. Silva; Florinda Costa. 2020. "Nd:YAG laser scribed zinc oxide on semi-flexible copper foils." Materials Letters: X 5, no. : 100038.
Silicon carbide (SiC) is a wide band gap material that is slowly but steadily asserting itself as a reliable alternative to silicon (Si) for high temperature electronics applications, in particular for the electrical vehicles industry. The passivation of SiC devices with diamond films is expected to decrease leakage currents and avoid premature breakdown of the devices, leading to more efficient devices. However, for an efficient passivation the interface between both materials needs to be virtually void free and high quality diamond films are required from the first stages of growth. In order to evaluate the impact of the deposition and seeding parameters in the properties of the deposits, diamond films were deposited on SiC substrates by hot filament chemical vapor deposition (HFCVD). Before the seeding step the substrates were exposed to diamond growth conditions (pre-treatment PT) and seeding was performed with a solution of detonation nanodiamond (DND) particles and with 6–12 and 40–60 μm grit. Diamond films were then grown at different temperatures and with different methane concentrations and the deposits were observed in a scanning electron microscope (SEM); their quality was assessed with Raman spectroscopy.
Debarati Mukherjee; Filipe Oliveira; Simone Camargo Trippe; Shlomo Rotter; Miguel Neto; Rui Silva; Awadesh Kumar Mallik; Ken Haenen; Carl-Mikael Zetterling; Joana Catarina Mendes. Deposition of diamond films on single crystalline silicon carbide substrates. Diamond and Related Materials 2019, 101, 107625 .
AMA StyleDebarati Mukherjee, Filipe Oliveira, Simone Camargo Trippe, Shlomo Rotter, Miguel Neto, Rui Silva, Awadesh Kumar Mallik, Ken Haenen, Carl-Mikael Zetterling, Joana Catarina Mendes. Deposition of diamond films on single crystalline silicon carbide substrates. Diamond and Related Materials. 2019; 101 ():107625.
Chicago/Turabian StyleDebarati Mukherjee; Filipe Oliveira; Simone Camargo Trippe; Shlomo Rotter; Miguel Neto; Rui Silva; Awadesh Kumar Mallik; Ken Haenen; Carl-Mikael Zetterling; Joana Catarina Mendes. 2019. "Deposition of diamond films on single crystalline silicon carbide substrates." Diamond and Related Materials 101, no. : 107625.
Monolithic mechanically reinforced CNTs-silica aerogel composites have been successfully synthesized by two-step sol-gel methodology, using methyltrimethoxysilane as the main silica precursor, combined with an ecofriendly ethanol/water mixture as solvent, and dried at ambient pressure. For an effective linkage of the carbon nanotubes with the silica network, the CNTs were submitted to a silanization treatment. With this approach, the chemical binding between the two phases takes place, with the silica particles following the elongated shape of CNTs, which leads to an improvement of the mechanical properties, with Young's modulus up to 201.5 kPa, when compared to the corresponding silica aerogel counterpart without CNTs (104.9 kPa). Moreover, the developed materials show high porosities (up to 95.8%), low densities (as low as 61.3 kg m−3), good thermal insulation performance of 31.2–44.1 mW m−1 K−1 and superhydrophobic character. The significant improvements regarding physical and mechanical properties make these composite aerogels attractive for several applications, ranging from thermal insulators to adsorbents.
Alyne Lamy-Mendes; Ana Violeta Girão; Rui Silva; Luísa Durães. Polysilsesquioxane-based silica aerogel monoliths with embedded CNTs. Microporous and Mesoporous Materials 2019, 288, 109575 .
AMA StyleAlyne Lamy-Mendes, Ana Violeta Girão, Rui Silva, Luísa Durães. Polysilsesquioxane-based silica aerogel monoliths with embedded CNTs. Microporous and Mesoporous Materials. 2019; 288 ():109575.
Chicago/Turabian StyleAlyne Lamy-Mendes; Ana Violeta Girão; Rui Silva; Luísa Durães. 2019. "Polysilsesquioxane-based silica aerogel monoliths with embedded CNTs." Microporous and Mesoporous Materials 288, no. : 109575.
Hybrid diamond–graphite nanoplatelet (DGNP) thin films are produced and applied to label-free impedimetric biosensors for the first time, using avidin detection as a proof of concept. The DGNPs are synthesized by microwave plasma chemical vapor deposition through H2/CH4/N2 gas mixtures in a reproducible and rapid single-step process. The material building unit consists of an inner two-dimensional-like nanodiamond with preferential vertical alignment covered by and covalently bound to nanocrystalline graphite grains, exhibiting {111}diamond||{0002}graphite epitaxy. The DGNP films’ morphostructural aspects are of interest for electrochemical transduction, in general, and for Faradaic impedimetric biosensors, in particular, combining enhanced surface area for biorecognition element loading and facile Faradaic charge transfer. Charge transfer rate constants in phosphate buffer saline/[Fe(CN)6]4– solution are shown to increase up to 5.6 × 10–3 cm s–1 upon N2 addition to DGNP synthesis. For the impedimetric detection of avidin, biotin molecules are covalently bound as avidin specific recognition elements on (3-aminopropyl)triethoxysilane-functionalized DGNP surfaces. Avidin quantification is attained within the 10–1000 μg mL–1 range following a logarithmic dependency. The limits of detection and of quantitation are 1.3 and 6.4 μg mL–1 (19 and 93 nM), respectively, and 2.3 and 13.8 μg mL–1 (33 and 200 nM) when considering the nonspecific response of the sensors.
Nuno F. Santos; Sónia O. Pereira; António J. S. Fernandes; Thiago L. Vasconcelos; Chung M. Fung; Bráulio S. Archanjo; Carlos A. Achete; Sofia R. Teixeira; Rui F. Silva; Florinda M. Costa. Physical Structure and Electrochemical Response of Diamond–Graphite Nanoplatelets: From CVD Synthesis to Label-Free Biosensors. ACS Applied Materials & Interfaces 2019, 11, 8470 -8482.
AMA StyleNuno F. Santos, Sónia O. Pereira, António J. S. Fernandes, Thiago L. Vasconcelos, Chung M. Fung, Bráulio S. Archanjo, Carlos A. Achete, Sofia R. Teixeira, Rui F. Silva, Florinda M. Costa. Physical Structure and Electrochemical Response of Diamond–Graphite Nanoplatelets: From CVD Synthesis to Label-Free Biosensors. ACS Applied Materials & Interfaces. 2019; 11 (8):8470-8482.
Chicago/Turabian StyleNuno F. Santos; Sónia O. Pereira; António J. S. Fernandes; Thiago L. Vasconcelos; Chung M. Fung; Bráulio S. Archanjo; Carlos A. Achete; Sofia R. Teixeira; Rui F. Silva; Florinda M. Costa. 2019. "Physical Structure and Electrochemical Response of Diamond–Graphite Nanoplatelets: From CVD Synthesis to Label-Free Biosensors." ACS Applied Materials & Interfaces 11, no. 8: 8470-8482.
In this paper, a numerical and an experimental approach are established to study the influence of the machining parameters on the resonance frequency shift of ultrasonic assisted turning. The numerical model incorporates the mechanical and electrical effect on the simulation mode shape and resonance frequency of entire ultrasonic equipment. It is numerically shown that the machining parameters’ variability promotes a resonance frequency shifting, and the depth of cut is suggested to have more effect than the feed rate. Experimental results demonstrated that for the same cutting speed and different depth of cut and feed, the frequency value shifts thus compromise the surface quality. With the frequency adjustment promoted by MMM system, surface roughness improves 10 and 14%, when the feed is increased from 0.045 to 0.18 mm/rev, respectively, for a depth of cut of 1.5 mm.
H. Puga; J. Grilo; Filipe Oliveira; R. F. Silva; Ana Violeta Girão. Influence of external loading on the resonant frequency shift of ultrasonic assisted turning: numerical and experimental analysis. The International Journal of Advanced Manufacturing Technology 2018, 101, 2487 -2496.
AMA StyleH. Puga, J. Grilo, Filipe Oliveira, R. F. Silva, Ana Violeta Girão. Influence of external loading on the resonant frequency shift of ultrasonic assisted turning: numerical and experimental analysis. The International Journal of Advanced Manufacturing Technology. 2018; 101 (9-12):2487-2496.
Chicago/Turabian StyleH. Puga; J. Grilo; Filipe Oliveira; R. F. Silva; Ana Violeta Girão. 2018. "Influence of external loading on the resonant frequency shift of ultrasonic assisted turning: numerical and experimental analysis." The International Journal of Advanced Manufacturing Technology 101, no. 9-12: 2487-2496.
Nitrogen-doped TiO2 nanoparticles with high specific surface area and photocatalytic activity under visible light were successfully produced using a modified sol-gel method with urea introduced as the nitrogen source. Different synthesis approaches and parameters such as doping temperature and urea to TiO2 molar ratio were tested to examine the best outcome regarding photocatalytic activity for both UV-A and visible light irradiation. UV-Vis diffuse reflectance characterization revealed a decrease in band gap from 3.24 to a minimum of 2.79 eV with the N-doping process. The photocatalytic Methylene Blue dye degradation assays suggests that the introduction of nitrogen in the TiO2 lattice cell can provide a higher efficiency under both UV-A and visible irradiation. The maximum photocatalytic activity was achieved for the nitrogen-doped powders prepared with the lowest urea:TiO2 molar ratio (1.5) as it was the formulation that promoted an enhancement in N-doping and particle specific surface area to 182 m2 g-1, despite the fact that the highest specific surface area was registered for undoped TiO2 nanoparticles (228 m2 g-1). A synthesis step variation was performed to enhance the specific surface area of nanoparticles and consequently the photocatalytic activity. This modification promoted an increase in specific surface area by a factor of ~5. XPS spectra confirmed a successful introduction of nitrogen in the TiO2 lattice up to 1.5 at.% for optimized powders, which is strongly dependant of the type of synthesis and the amount of dopant species added during the doping process.
Juliana Marques; Tiago D. Gomes; Marta A. Forte; Rui F. Silva; Carlos J. Tavares. A new route for the synthesis of highly-active N-doped TiO2 nanoparticles for visible light photocatalysis using urea as nitrogen precursor. Catalysis Today 2018, 326, 36 -45.
AMA StyleJuliana Marques, Tiago D. Gomes, Marta A. Forte, Rui F. Silva, Carlos J. Tavares. A new route for the synthesis of highly-active N-doped TiO2 nanoparticles for visible light photocatalysis using urea as nitrogen precursor. Catalysis Today. 2018; 326 ():36-45.
Chicago/Turabian StyleJuliana Marques; Tiago D. Gomes; Marta A. Forte; Rui F. Silva; Carlos J. Tavares. 2018. "A new route for the synthesis of highly-active N-doped TiO2 nanoparticles for visible light photocatalysis using urea as nitrogen precursor." Catalysis Today 326, no. : 36-45.
Nanocomposite thin films, with noble nanoparticles dispersed in a dielectric matrix, are known to present unique optical properties. Based on the Localized Surface Plasmon Resonance (LSPR) phenomenon, these “nanoplasmonic” materials are the basis of a wide range of technological applications, namely (bio)molecular LSPR-sensors. They are regulated by the concentration, size, shape and distribution of the nanoparticles and dielectric environment properties. In this work, the possibility of using aluminium nitride (AlN) as a host dielectric matrix for LSPR films was evaluated. For this purpose, nanocomposite Au:AlN films were prepared by magnetron sputtering, followed by thermal annealing to promote the growth of the nanoparticles. Three sets of films were deposited with atomic Au concentrations of 2.2, 4.4 and 6.0 at.%. LSPR bands appeared from the temperature of 500 °C, with resonance positions of 520–540 nm. The films showed potential to be tested in LSPR-sensing applications due to their optical responses.
Rui P. Domingues; Marco S. Rodrigues; Manuela Proença; Diogo Costa; Eduardo Alves; Nuno Pessoa Barradas; Filipe Oliveira; Rui F. Silva; Joel Borges; Filipe Vaz. Thin films composed of Au nanoparticles embedded in AlN: Influence of metal concentration and thermal annealing on the LSPR band. Vacuum 2018, 157, 414 -421.
AMA StyleRui P. Domingues, Marco S. Rodrigues, Manuela Proença, Diogo Costa, Eduardo Alves, Nuno Pessoa Barradas, Filipe Oliveira, Rui F. Silva, Joel Borges, Filipe Vaz. Thin films composed of Au nanoparticles embedded in AlN: Influence of metal concentration and thermal annealing on the LSPR band. Vacuum. 2018; 157 ():414-421.
Chicago/Turabian StyleRui P. Domingues; Marco S. Rodrigues; Manuela Proença; Diogo Costa; Eduardo Alves; Nuno Pessoa Barradas; Filipe Oliveira; Rui F. Silva; Joel Borges; Filipe Vaz. 2018. "Thin films composed of Au nanoparticles embedded in AlN: Influence of metal concentration and thermal annealing on the LSPR band." Vacuum 157, no. : 414-421.
Paulo Pedrosa; Marco S. Rodrigues; Miguel A. Neto; Filipe J. Oliveira; Rui Silva; Joel Borges; Margarida Amaral; António Ferreira; Luís H. Godinho; Sandra Carvalho; Filipe Vaz. Properties of CrN thin films deposited in plasma-activated ABS by reactive magnetron sputtering. Surface and Coatings Technology 2018, 349, 858 -866.
AMA StylePaulo Pedrosa, Marco S. Rodrigues, Miguel A. Neto, Filipe J. Oliveira, Rui Silva, Joel Borges, Margarida Amaral, António Ferreira, Luís H. Godinho, Sandra Carvalho, Filipe Vaz. Properties of CrN thin films deposited in plasma-activated ABS by reactive magnetron sputtering. Surface and Coatings Technology. 2018; 349 ():858-866.
Chicago/Turabian StylePaulo Pedrosa; Marco S. Rodrigues; Miguel A. Neto; Filipe J. Oliveira; Rui Silva; Joel Borges; Margarida Amaral; António Ferreira; Luís H. Godinho; Sandra Carvalho; Filipe Vaz. 2018. "Properties of CrN thin films deposited in plasma-activated ABS by reactive magnetron sputtering." Surface and Coatings Technology 349, no. : 858-866.
Tin dioxide thin films are grown at low-moderate temperature using a non-hydrolytic atomic layer deposition process. Granular SnO2 thin films are obtained from tin(IV) tetra-butoxide reacting with acetic acid, at temperatures as low as 75 °C. Influence of pulse length of both reactants and of the deposition temperature on the saturation is studied. A narrow ALD window is established between 150 and 175 °C with a growth per cycle of 0.07 nm and with a linear growth as a function of the number of cycles. Above 200 °C decomposition of the tin precursor is not negligible. Microstructure and morphology of the as-prepared films as well as the influence of the deposition parameters are investigated using electron and atomic force microscopies. The band gap of the obtained films is determined using UV-visible spectroscopy. Finally the use of the SnO2 coated carbon nanotubes as gas sensing layer is discussed.
Catherine Marichy; Ricardo Manuel Silva; Nicola Pinna; Marc Willinger; Nicola Donato; Giovanni Neri. (Invited) Non-Aqueous Atomic Layer Deposition of SnO2 for Gas Sensing Application. ECS Transactions 2018, 86, 55 -65.
AMA StyleCatherine Marichy, Ricardo Manuel Silva, Nicola Pinna, Marc Willinger, Nicola Donato, Giovanni Neri. (Invited) Non-Aqueous Atomic Layer Deposition of SnO2 for Gas Sensing Application. ECS Transactions. 2018; 86 (6):55-65.
Chicago/Turabian StyleCatherine Marichy; Ricardo Manuel Silva; Nicola Pinna; Marc Willinger; Nicola Donato; Giovanni Neri. 2018. "(Invited) Non-Aqueous Atomic Layer Deposition of SnO2 for Gas Sensing Application." ECS Transactions 86, no. 6: 55-65.
Synthesis & applications of advanced silica aerogel composites incorporating carbon nanostructures and their valuable properties for thermal insulation, adsorption or electrodes.
Alyne Lamy-Mendes; Rui F. Silva; Luisa Durães. Advances in carbon nanostructure–silica aerogel composites: a review. Journal of Materials Chemistry A 2017, 6, 1340 -1369.
AMA StyleAlyne Lamy-Mendes, Rui F. Silva, Luisa Durães. Advances in carbon nanostructure–silica aerogel composites: a review. Journal of Materials Chemistry A. 2017; 6 (4):1340-1369.
Chicago/Turabian StyleAlyne Lamy-Mendes; Rui F. Silva; Luisa Durães. 2017. "Advances in carbon nanostructure–silica aerogel composites: a review." Journal of Materials Chemistry A 6, no. 4: 1340-1369.
Background: Massive rotator cuff tears (MRCTs) represent a major clinical concern, especially when degeneration and chronicity are involved, which highly compromise healing capacity. Purpose: To study the effect of the secretome of mesenchymal stem cells (MSCs) on tendon cells (TCs) followed by the combination of these activated TCs with an electrospun keratin-based scaffold to develop a tissue engineering strategy to improve tendon-bone interface (TBi) healing in a chronic MRCT rat model. Study Design: Controlled laboratory study. Methods: Human TCs (hTCs) cultured with the human MSCs (hMSCs) secretome (as conditioned media [CM]) were combined with keratin electrospun scaffolds and further implanted in a chronic MRCT rat model. Wistar-Han rats (N = 15) were randomly assigned to 1 of 3 groups: untreated lesion (MRCT group, n = 5), lesion treated with a scaffold only (scaffold-only group, n = 5), and lesion treated with a scaffold seeded with hTCs preconditioned with hMSCs-CM (STC_hMSC_CM group, n = 5). After sacrifice, 16 weeks after surgery, the rotator cuff TBi was harvested for histological analysis and biomechanical testing. Results: The hMSCs secretome increased hTCs viability and density in vitro. In vivo, a significant improvement of the tendon maturing score was observed in the STC_hMSC_CM group (mean ± standard error of the mean, 15.6 ± 1.08) compared with the MRCT group (11.0 ± 1.38; P < .05). Biomechanical tests revealed a significant increase in the total elongation to rupture (STC_hMSC_CM, 11.99 ± 3.30 mm; scaffold-only, 9.89 ± 3.47 mm; MRCT, 5.86 ± 3.16 mm; P < .05) as well as a lower stiffness (STC_hMSC_CM, 6.25 ± 1.74 N/mm; scaffold-only, 6.72 ± 1.28 N/mm; MRCT, 11.54 ± 2.99 N/mm; P < .01). Conclusion: The results demonstrated that hMSCs-CM increased hTCs viability and density in vitro. Clear benefits also were observed when these primed cells were integrated into a tissue engineering strategy with an electrospun keratin scaffold, as evidenced by improved histological and biomechanical properties for the STC_hMSC_CM group compared with the MRCT group. Clinical Relevance: This work supports further investigation into the use of MSC secretome for priming TCs toward a more differentiated phenotype, and it promotes the tissue engineering strategy as a promising modality to help improve treatment outcomes for chronic MRCTs.
Nuno Sevivas; Fábio Teixeira; Raquel Portugal; Bruno Direito-Santos; João Espregueira-Mendes; Filipe Oliveira; Rui Silva; Nuno Sousa; Wan Ting Sow; Luong Nguyen; Sow Wan Ting; Antonio Salgado. Mesenchymal Stem Cell Secretome Improves Tendon Cell Viability In Vitro and Tendon-Bone Healing In Vivo When a Tissue Engineering Strategy Is Used in a Rat Model of Chronic Massive Rotator Cuff Tear. The American Journal of Sports Medicine 2017, 46, 449 -459.
AMA StyleNuno Sevivas, Fábio Teixeira, Raquel Portugal, Bruno Direito-Santos, João Espregueira-Mendes, Filipe Oliveira, Rui Silva, Nuno Sousa, Wan Ting Sow, Luong Nguyen, Sow Wan Ting, Antonio Salgado. Mesenchymal Stem Cell Secretome Improves Tendon Cell Viability In Vitro and Tendon-Bone Healing In Vivo When a Tissue Engineering Strategy Is Used in a Rat Model of Chronic Massive Rotator Cuff Tear. The American Journal of Sports Medicine. 2017; 46 (2):449-459.
Chicago/Turabian StyleNuno Sevivas; Fábio Teixeira; Raquel Portugal; Bruno Direito-Santos; João Espregueira-Mendes; Filipe Oliveira; Rui Silva; Nuno Sousa; Wan Ting Sow; Luong Nguyen; Sow Wan Ting; Antonio Salgado. 2017. "Mesenchymal Stem Cell Secretome Improves Tendon Cell Viability In Vitro and Tendon-Bone Healing In Vivo When a Tissue Engineering Strategy Is Used in a Rat Model of Chronic Massive Rotator Cuff Tear." The American Journal of Sports Medicine 46, no. 2: 449-459.
Ceramic cutting inserts coated with ten-fold alternating micro- and nanocrystalline diamond (MCD/NCD) layers grown by hot filament chemical vapor deposition (CVD) were tested in the machining of an Al based metallic matrix composite (MMC) containing 15 vol % Al2O3 particles. Inserts with total coating thicknesses of approximately 12 µm and 24 µm were produced and used in turning: cutting speed (v) of 250 to 1000 m·min−1; depth of cut (DOC) from 0.5 to 3 mm and feed (f) between 0.1 and 0.4 mm·rev−1. The main cutting force increases linearly with DOC (ca. 294 N per mm) and with feed (ca. 640 N per mm·rev−1). The thicker coatings work within the following limits: DOC up to 1.5 mm and maximum speeds of 750 m·min−1 for feeds up to 0.4 mm·rev−1. Flank wear is predominant but crater wear is also observed due to the negative tool normal rake. Layer-by-layer wear of the tool rake, and not total delamination from the substrate, evidenced one of the advantages of using a multilayer design. The MCD/NCD multilayer diamond coated indexable inserts have longer tool life than most CVD diamond systems and behave as well as most polycrystalline diamond (PCD) tools.
Mohammadmehdi Shabani; Joaquim Sacramento; Filipe Oliveira; Rui F. Silva. Multilayer CVD Diamond Coatings in the Machining of an Al6061-15 Vol % Al2O3 Composite. Coatings 2017, 7, 165 .
AMA StyleMohammadmehdi Shabani, Joaquim Sacramento, Filipe Oliveira, Rui F. Silva. Multilayer CVD Diamond Coatings in the Machining of an Al6061-15 Vol % Al2O3 Composite. Coatings. 2017; 7 (10):165.
Chicago/Turabian StyleMohammadmehdi Shabani; Joaquim Sacramento; Filipe Oliveira; Rui F. Silva. 2017. "Multilayer CVD Diamond Coatings in the Machining of an Al6061-15 Vol % Al2O3 Composite." Coatings 7, no. 10: 165.