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We report the structural, morphological and optical characterization, and the application of sodium‐cerium molybdate (NaCe(MoO4)2) as a promising photoelectroactive material for water splitting. Information on these several properties was obtained by X‐ray diffraction, Raman spectroscopy, scanning electron microscopy and UV–vis–NIR diffuse reflectance. For the photoelectrochemical tests, NaCe(MoO4)2 microcrystals were deposited on conductive indium‐tin oxide (ITO) glass substrate by drop‐coating, and the activity of the as‐prepared photoanode towards oxygen evolution reaction was investigated in the absence and presence of blue light‐emitting diode irradiation. Studies carried out by linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy attested to a significant photoelectroactivity of molybdate associated with the fast electron‐hole pairs generation. The steady‐state photocurrent density recorded under irradiation achieved a remarkable increase, varying from 1.5 µA cm–2 (light off) to 44.1 µA cm–2 (light on), in addition, it presents high stability after on‐off cycles, what proves the proper performance of NaCe(MoO4)2/ITO as photoanode for water splitting.
João Victor Barbosa Moura; Antonio Amison Gomes De Souza; Paulo De Tarso Cavalcante Freire; Cleanio Da Luz Lima; Thiago Mielle Brito Ferreira Oliveira. Blue‐light‐excited NaCe(MoO 4 ) 2 microcrystals for photoelectrochemical water splitting. International Journal of Applied Ceramic Technology 2020, 1 .
AMA StyleJoão Victor Barbosa Moura, Antonio Amison Gomes De Souza, Paulo De Tarso Cavalcante Freire, Cleanio Da Luz Lima, Thiago Mielle Brito Ferreira Oliveira. Blue‐light‐excited NaCe(MoO 4 ) 2 microcrystals for photoelectrochemical water splitting. International Journal of Applied Ceramic Technology. 2020; ():1.
Chicago/Turabian StyleJoão Victor Barbosa Moura; Antonio Amison Gomes De Souza; Paulo De Tarso Cavalcante Freire; Cleanio Da Luz Lima; Thiago Mielle Brito Ferreira Oliveira. 2020. "Blue‐light‐excited NaCe(MoO 4 ) 2 microcrystals for photoelectrochemical water splitting." International Journal of Applied Ceramic Technology , no. : 1.
In this work, we present the study of the temperature-dependent behavior of silver orthophosphate (Ag3PO4) microcrystals using in situ Raman scattering. The Ag3PO4 as-synthesized microcrystals were prepared by the precipitation method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and infrared spectroscopy, and differential scanning calorimetry (DSC). Temperature-dependent phonon dynamics were performed on Ag3PO4 microcrystals and pointed to a first-order phase transition in the temperature range 500 °C - 515 °C: Phase I (25 °C - 500 °C) → Phase II (515 °C - 590 °C). The phase transition is reversible and a temperature hysteresis was observed during the heating – cooling process: Phase II (590 °C - 470 °C) → Phase I (455 °C - 25 °C). The reversible phase transition is related to the distortion of the tetrahedral symmetry of PO4 caused by the decrease in the crystalline order. DSC analysis confirmed the results of temperature-dependent Raman spectroscopy.
J.V.B. Moura; C.D. De Abreu Lima; E.A.O. Melo; V.E. Santos; W.C. Ferreira; P.T.C. Freire. Temperature-dependent phonon dynamics of Ag3PO4 microcrystals. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2020, 249, 119339 .
AMA StyleJ.V.B. Moura, C.D. De Abreu Lima, E.A.O. Melo, V.E. Santos, W.C. Ferreira, P.T.C. Freire. Temperature-dependent phonon dynamics of Ag3PO4 microcrystals. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2020; 249 ():119339.
Chicago/Turabian StyleJ.V.B. Moura; C.D. De Abreu Lima; E.A.O. Melo; V.E. Santos; W.C. Ferreira; P.T.C. Freire. 2020. "Temperature-dependent phonon dynamics of Ag3PO4 microcrystals." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 249, no. : 119339.
A basic characterization of novel epoxy matrix composites incorporated with up to 40 vol% of processed leaf fibers from the Copernicia prunifera palm tree, known as carnauba fibers, was performed. The tensile properties for the composite reinforced with 40 vol% of carnauba fibers showed an increase (40%) in the tensile strength and (69%) for the elastic modulus. All composites presented superior elongation values in comparison to neat epoxy. Izod impact tests complemented by fibers/matrix interfacial strength evaluation by pullout test and Fourier transformed infrared (FTIR) analysis revealed for the first time a significant reinforcement effect (> 9 times) caused by the carnauba fiber to polymer matrix. Additional thermogravimetric analysis (TG/DTG) showed the onset of thermal degradation for the composites (326 ~ 306 °C), which represents a better thermal stability than the plain carnauba fiber (267 °C) but slightly lower than that of the neat epoxy (342 °C). Differential scanning calorimetry (DSC) disclosed an endothermic peak at 63 °C for the neat epoxy associated with the glass transition temperature (Tg). DSC endothermic peaks for the composites, between 73 to 103 °C, and for the plain carnauba fibers, 107 °C, are attributed to moisture release. Dynamic mechanical analysis confirms Tg of 64 °C for the neat epoxy and slightly higher composite values (82–84 °C) due to the carnauba fiber interference with the epoxy macromolecular chain mobility. Both by its higher impact resistance and thermal behavior, the novel carnauba fibers epoxy composites might be considered a viable substitute for commonly used glass fiber composites.
Raí Felipe Pereira Junio; Lucio Fabio Cassiano Nascimento; Lucas De Mendonça Neuba; Andressa Teixeira Souza; João Victor Barbosa Moura; Fábio Da Costa Garcia Filho; Sergio Neves Monteiro. Copernicia Prunifera Leaf Fiber: A Promising New Reinforcement for Epoxy Composites. Polymers 2020, 12, 2090 .
AMA StyleRaí Felipe Pereira Junio, Lucio Fabio Cassiano Nascimento, Lucas De Mendonça Neuba, Andressa Teixeira Souza, João Victor Barbosa Moura, Fábio Da Costa Garcia Filho, Sergio Neves Monteiro. Copernicia Prunifera Leaf Fiber: A Promising New Reinforcement for Epoxy Composites. Polymers. 2020; 12 (9):2090.
Chicago/Turabian StyleRaí Felipe Pereira Junio; Lucio Fabio Cassiano Nascimento; Lucas De Mendonça Neuba; Andressa Teixeira Souza; João Victor Barbosa Moura; Fábio Da Costa Garcia Filho; Sergio Neves Monteiro. 2020. "Copernicia Prunifera Leaf Fiber: A Promising New Reinforcement for Epoxy Composites." Polymers 12, no. 9: 2090.
Temperature-dependent Raman study was performed in order to obtain information on structural changes induced by the temperature in the β-Ag2WO4 crystal. The stability of the hexagonal structure (P63/m) phase of the Ag2WO4 crystal was accessed, and our results indicated that this material undergoes a sequence of three phase transformations, which were observed at 413-433, 483–493 and at approximately 613 K. In these transitions, the changes that occurred in the Raman spectra were characterized by the appearance and disappearance of new Raman bands. The results lead us to assume the following sequence of phase transitions: beta to phase II, phase II to phase III, and phase III to alpha phase. After temperature decreases from the alpha phase at the highest temperature to room temperature, another phase transition occurred, but the final phase is not the β-Ag2WO4 phase. Such phase transition is irreversible and relates to tilting and/or rotations of the WO4 tetrahedra, which leads to a disorder at the WO4 sites. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) were also performed to evaluate the Raman spectra data of the β-Ag2WO4 to identify the correlations with the phase transformations that occurred during the increasing and decreasing of temperatures.
João Victor Barbosa Moura; C.D. De Abreu Lima; A.J. Ramiro de Castro; P.T.C. Freire; G.D. Saraiva. Temperature-induced phase transitions in metastable β-Ag2WO4: a Raman scattering study. Vibrational Spectroscopy 2020, 110, 103135 .
AMA StyleJoão Victor Barbosa Moura, C.D. De Abreu Lima, A.J. Ramiro de Castro, P.T.C. Freire, G.D. Saraiva. Temperature-induced phase transitions in metastable β-Ag2WO4: a Raman scattering study. Vibrational Spectroscopy. 2020; 110 ():103135.
Chicago/Turabian StyleJoão Victor Barbosa Moura; C.D. De Abreu Lima; A.J. Ramiro de Castro; P.T.C. Freire; G.D. Saraiva. 2020. "Temperature-induced phase transitions in metastable β-Ag2WO4: a Raman scattering study." Vibrational Spectroscopy 110, no. : 103135.
Doping tungsten oxide with other metals is a promising approach for obtaining improved properties as compared with its undoped counterpart. Here, the effect of molybdenum doping on the morphology, crystalline structure, and adsorption properties of nanostructured WO3 was investigated. Undoped and Mo-doped hexagonal WO3 (h-WO3) nanowire bundles were synthesized by hydrothermal method. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, scanning transmission electron microscopy, selected-area electron diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The surface areas of the samples were evaluated by N2 adsorption–desorption isotherm, and their adsorption properties were evaluated based on their ability to adsorb cationic dye methylene blue (MB) in aqueous solution. Upon the addition of molybdenum, the morphology of the h-WO3 nanowire changes from large bundles to narrow bundles with a higher number of isolated thin nanowires. Mo doping also has changed the crystalline structure, porosity, and surface area of the bundled h-WO3 nanowires. Interestingly, Mo-doped h-WO3 nanowire bundles exhibit an enhanced and faster MB uptake, thus implying that Mo-doping WO3 can be an effective strategy to improve the adsorption properties, thereby adding value in developing alternative adsorption-based methods for wastewater treatment.
J. V. Silveira; E. C. Moraes; João Victor Barbosa Moura; A. Ghosh; C. A. Senna; Braulio Archanjo; Thiago Vasconcelos; A. G. Souza Filho; P. T. C. Freire; C. Luz-Lima. Mo-doped WO3 nanowires for adsorbing methylene blue dye from wastewater. Journal of Materials Science 2020, 55, 6429 -6440.
AMA StyleJ. V. Silveira, E. C. Moraes, João Victor Barbosa Moura, A. Ghosh, C. A. Senna, Braulio Archanjo, Thiago Vasconcelos, A. G. Souza Filho, P. T. C. Freire, C. Luz-Lima. Mo-doped WO3 nanowires for adsorbing methylene blue dye from wastewater. Journal of Materials Science. 2020; 55 (15):6429-6440.
Chicago/Turabian StyleJ. V. Silveira; E. C. Moraes; João Victor Barbosa Moura; A. Ghosh; C. A. Senna; Braulio Archanjo; Thiago Vasconcelos; A. G. Souza Filho; P. T. C. Freire; C. Luz-Lima. 2020. "Mo-doped WO3 nanowires for adsorbing methylene blue dye from wastewater." Journal of Materials Science 55, no. 15: 6429-6440.
Among the several applications of molybdates, the photocatalysis is a highly appealing process with multiple applications, mainly in the fields of pollution removal. In view of this, the main objective of this work was to study the potentialities and the evolution of the technological features inherent to patent deposits, and panorama of publications of articles on molybdates, as well as the related photocatalytic a properties, specifically in the range years from 2000 to 2017. The study was performed using information from the Web of Science, SciELO, European Patent Office (EPO), United States Patent and Trademark Office (USPTO), Derwent Innovations Index, and the database of the National Institute of Industrial Property (INPI) of Brazil. The research has shown growth in the number of patents and articles over the years. Brazil is well positioned in the world ranking of publications of articles containing photocatalytic properties of molybdates, but does not display patents filed with INPI. Regarding the world stage, the results indicate a promising area with significant growth in the number of patents and scientific articles.
João Victor Barbosa Moura; Edilainea Alves Oliveira Melo; Cleanio Luz Lima; Paulo De Tarso Cavalcante Freire. PHOTOCATALYTIC ACTIVITY OF MOLYBDATES: A TECHNOLOGICAL PROSPECTING. Revista Gestão Inovação e Tecnologias 2020, 10, 5302 -5313.
AMA StyleJoão Victor Barbosa Moura, Edilainea Alves Oliveira Melo, Cleanio Luz Lima, Paulo De Tarso Cavalcante Freire. PHOTOCATALYTIC ACTIVITY OF MOLYBDATES: A TECHNOLOGICAL PROSPECTING. Revista Gestão Inovação e Tecnologias. 2020; 10 (1):5302-5313.
Chicago/Turabian StyleJoão Victor Barbosa Moura; Edilainea Alves Oliveira Melo; Cleanio Luz Lima; Paulo De Tarso Cavalcante Freire. 2020. "PHOTOCATALYTIC ACTIVITY OF MOLYBDATES: A TECHNOLOGICAL PROSPECTING." Revista Gestão Inovação e Tecnologias 10, no. 1: 5302-5313.
The synthesis of rare-earth-doped barium tungstate has increased in recent decades due to the attractive electrical and optical properties of the material. In this study, erbium-doped barium tungstate was synthesized by the co-precipitation method with three different concentrations: Ba(1-x)ErxWO4 (where x = 0.00, 0.01, and 0.02). The materials were characterized by X-ray diffraction (XRD), Raman and Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Subsequently, the samples were subjected to temperature variations in the range of 123–293 K, and their Raman spectra were collected to observe the structural changes induced by Er doping. We observed that at low temperatures, there was no indication of phase transition for pure tungstate (BaWO4); however, for doped tungstates, changes were observed in the Raman spectra, showing an unexpected structural phase transition.
I.P. Carvalho; R.B. Sousa; J.M.E. Matos; J.V.B. Moura; P.T.C. Freire; G.S. Pinheiro; C. Luz-Lima. Low-temperature induced phase transitions in BaWO4:Er3+ microcrystals: A Raman scattering study. Journal of Molecular Structure 2019, 1204, 127498 .
AMA StyleI.P. Carvalho, R.B. Sousa, J.M.E. Matos, J.V.B. Moura, P.T.C. Freire, G.S. Pinheiro, C. Luz-Lima. Low-temperature induced phase transitions in BaWO4:Er3+ microcrystals: A Raman scattering study. Journal of Molecular Structure. 2019; 1204 ():127498.
Chicago/Turabian StyleI.P. Carvalho; R.B. Sousa; J.M.E. Matos; J.V.B. Moura; P.T.C. Freire; G.S. Pinheiro; C. Luz-Lima. 2019. "Low-temperature induced phase transitions in BaWO4:Er3+ microcrystals: A Raman scattering study." Journal of Molecular Structure 1204, no. : 127498.
This study reports the antibacterial properties and modulation analysis of antibiotic activity by NaCe(MoO4)2 microcrystals as well as their structural and morphological characterization. Evaluation of the antibacterial and antibiotic-modulating activity was carried out using the broth microdilution method. The Minimum Inhibitory Concentrations (MICs) of the compounds were expressed as the geometric mean of the triplicate values obtained through the use of Resazurin. Compound concentrations in the plates ranged from 512 to 0.5 μg/mL. Regarding its direct antibacterial activity, NaCe(MoO4)2 had a MIC ≥ 1024 μg/mL against all studied strains. As for its modulatory effect, it presented synergism with the antibiotic Gentamicin against the S. aureus strain and with Norfloxacin against E. coli, causing a reduction of 75% and 60%, respectively, in the antibiotic quantity required to have the same effect on the strain in study.
João Victor Barbosa Moura; T.S. Freitas; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; A.T.L. Santos; J.H. Da Silva; C. Luz-Lima; H.D.M. Coutinho. Antibacterial properties and modulation analysis of antibiotic activity of NaCe(MoO4)2 microcrystals. Microbial Pathogenesis 2018, 126, 258 -262.
AMA StyleJoão Victor Barbosa Moura, T.S. Freitas, R.P. Cruz, R.L.S. Pereira, A.R.P. Silva, A.T.L. Santos, J.H. Da Silva, C. Luz-Lima, H.D.M. Coutinho. Antibacterial properties and modulation analysis of antibiotic activity of NaCe(MoO4)2 microcrystals. Microbial Pathogenesis. 2018; 126 ():258-262.
Chicago/Turabian StyleJoão Victor Barbosa Moura; T.S. Freitas; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; A.T.L. Santos; J.H. Da Silva; C. Luz-Lima; H.D.M. Coutinho. 2018. "Antibacterial properties and modulation analysis of antibiotic activity of NaCe(MoO4)2 microcrystals." Microbial Pathogenesis 126, no. : 258-262.
Temperature-dependent Raman spectroscopic study has been performed on scheelite-type sodium‑cerium molybdate - NaCe(MoO4)2 - in the temperature range 113–873 K. This study provides phonon properties of NaCe(MoO4)2, which are very important to understand the mechanism governing eventual phase transitions undergone by the structure, since phonons are very sensitive to structural changes. The ambient scheelite phase remains stable in a low-temperature range (113–293 K), and no relevant modification is observed in the Raman spectra. However, the experiments reveal the existence of one reversible phase transition at high-temperature. The vibrational spectra of NaCe(MoO4)2 system showed anomalies above 748 K, where overlaps of some bands and the appearance of a band at 458 cm−1 are observed. These modifications were attributed to an isostructural phase transition and a discussion about the possible mechanism of this phase transition is furnished.
J.V.B. Moura; C. Luz-Lima; G.S. Pinheiro; P.T.C. Freire. Temperature-induced isostructural phase transition on NaCe(MoO4)2 system: A Raman scattering study. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2018, 208, 229 -235.
AMA StyleJ.V.B. Moura, C. Luz-Lima, G.S. Pinheiro, P.T.C. Freire. Temperature-induced isostructural phase transition on NaCe(MoO4)2 system: A Raman scattering study. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 2018; 208 ():229-235.
Chicago/Turabian StyleJ.V.B. Moura; C. Luz-Lima; G.S. Pinheiro; P.T.C. Freire. 2018. "Temperature-induced isostructural phase transition on NaCe(MoO4)2 system: A Raman scattering study." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 208, no. : 229-235.
In this study, galvanic sludge waste (GSW) was characterized in order to identify its chemical and structural properties, allowing indicate reuse, treatment and final disposal methods, and evaluate the environmental hazards. The characterization of the galvanic sludge sample originating from a surface treatment plant from galvanic industries of semi-jewels in the Cariri region, NE of Brazil was performed. The chemical characterization of the samples by flame atomic absorption spectroscopy (FAAS) and X-Ray Fluorescence (XRF) showed that Zn and Cu are the predominant elements. However, elements like Ni, Cd, Mn, Fe, Cr and Co are present as a minority or as trace constituents. The concentrations of residues were higher, except Ni, in the LM industry (27 g Zn.kg -1, 194 g Cu.kg -1, 8 g Fe.kg-1, 538 mg Cd.kg -1, 227 mg Ni.kg -1, 73.5 mg Cr.kg1, 14 mg Co.kg-1) in relation to LJ (11 g Zn.kg-1, 3 g Fe.kg-1, 102 g Cu.kg-1, 2 g Cd.kg-1, 141 mg Ni.kg-1, 11 mg Co.kg-1), denoting that there is no uniform standard in the treatment process of the effluent from baths for Metal deposition. According to the standard procedure (Brazilian norm NBR10004/04) the elements Cd and Cr are the main constituents responsible for the classification of the residues as hazardous. The X-ray diffractogram of the dried galvanic sludge only revealed the presence of BaSO4 and CuO as crystalline phases, a result which agrees with the results from FT-IR. The results point to an attractive way of valorizing GSW avoiding the negative impact associated with its disposal in landfills.
Cícero Lucas Martins De Oliveira; Francisco José De Paula Filho; João Victor Barbosa Moura; Daniel Muller G. Freitas; Marcelo Oliveira Santiago. Characterization of Galvanic Sludges Waste Derived of the Metal Plating Industry from Cariri Region, Northeastern of Brazil. Materials Science Forum 2018, 930, 541 -545.
AMA StyleCícero Lucas Martins De Oliveira, Francisco José De Paula Filho, João Victor Barbosa Moura, Daniel Muller G. Freitas, Marcelo Oliveira Santiago. Characterization of Galvanic Sludges Waste Derived of the Metal Plating Industry from Cariri Region, Northeastern of Brazil. Materials Science Forum. 2018; 930 ():541-545.
Chicago/Turabian StyleCícero Lucas Martins De Oliveira; Francisco José De Paula Filho; João Victor Barbosa Moura; Daniel Muller G. Freitas; Marcelo Oliveira Santiago. 2018. "Characterization of Galvanic Sludges Waste Derived of the Metal Plating Industry from Cariri Region, Northeastern of Brazil." Materials Science Forum 930, no. : 541-545.
This study reports the synthesis and characterization of PbMoO4 nanocrystals and the antibacterial properties and modulation of their antibiotic activity. Lead molybdate nanocrystals were obtained through the conventional hydrothermal method, and the structural, vibrational and morphological properties of the sample were determined using X-ray diffraction, Raman and infrared spectroscopy, and scanning electron microscopy images. The obtained samples present scheelite-type tetragonal structure (space group I41/a) without secondary phases, and the Raman spectrum shows the formation of PbMoO4 structurally ordered at short-range, confirming the quality of the samples. The antibacterial and antibiotic-modulation activities were performed in triplicate using the microdilution method. The minimum inhibitory concentration (MIC) of antibiotics alone or in association with PbMoO4, were demonstrated using geometric mean. When assayed directly, the PbMoO4 presented a MIC ≥ 1024 μg/mL against all bacterial strains tested. When in association with the gentamicin against Staphylococcus aureus, a synergism was observed reducing 37.5% the MIC. However, in the assays against the Gram-negative strains was observed that the presence of lead affected the effect of the antibiotic, leading to an antagonism.
João Victor Barbosa Moura; T.S. Freitas; A.R.P. Silva; A.T.L. Santos; J.H. da Silva; R.P. Cruz; R.L.S. Pereira; P.T.C. Freire; C. Luz-Lima; G.S. Pinheiro; H.D.M. Coutinho. Synthesis, characterizations, and antibacterial properties of PbMoO4 nanocrystals. Arabian Journal of Chemistry 2018, 11, 739 -746.
AMA StyleJoão Victor Barbosa Moura, T.S. Freitas, A.R.P. Silva, A.T.L. Santos, J.H. da Silva, R.P. Cruz, R.L.S. Pereira, P.T.C. Freire, C. Luz-Lima, G.S. Pinheiro, H.D.M. Coutinho. Synthesis, characterizations, and antibacterial properties of PbMoO4 nanocrystals. Arabian Journal of Chemistry. 2018; 11 (6):739-746.
Chicago/Turabian StyleJoão Victor Barbosa Moura; T.S. Freitas; A.R.P. Silva; A.T.L. Santos; J.H. da Silva; R.P. Cruz; R.L.S. Pereira; P.T.C. Freire; C. Luz-Lima; G.S. Pinheiro; H.D.M. Coutinho. 2018. "Synthesis, characterizations, and antibacterial properties of PbMoO4 nanocrystals." Arabian Journal of Chemistry 11, no. 6: 739-746.
Laser-induced thermal effects on the hexagonal MoO3 nanorods at different power density levels were studied using Raman spectroscopy and scanning electron microscopy techniques. The structural features of the nanorods were accompanied by varying the incident laser power from 8.0 to 600 mW by using a gradual increasing rate and a sudden increasing incident laser power. It was shown that the photoeffects observed on the MoO3 nanorods critically depends of the exposure rate. By gradually increasing the incident laser power up to 600 mW, morphology of the nanorods were completely preserved, and the observed thermal behavior was discussed on the basis of thermal contact at nanoscale. However, when the irradiation intensity was suddenly increased, it was observed that overheating of h-MoO3 nanorods at relatively lower laser powers (80 mW) sublimate the nanorods around the laser spot region. The MoO3 molecules on vapor-phase at high temperatures condense and crystallize next to the laser spot on the orthorhombic (α-MoO3) and monoclinic (β-MoO3) phases. Furthermore, the nanorods closest to the laser spot region undergo a structural phase (and morphological) transition from h-MoO3 phase to α-MoO3 phase.
J.V. Silveira; J.V.B. Moura; C. Luz-Lima; P.T.C. Freire; A.G. Souza Filho. Laser-induced thermal effects in hexagonal MoO3 nanorods. Vibrational Spectroscopy 2018, 98, 145 -151.
AMA StyleJ.V. Silveira, J.V.B. Moura, C. Luz-Lima, P.T.C. Freire, A.G. Souza Filho. Laser-induced thermal effects in hexagonal MoO3 nanorods. Vibrational Spectroscopy. 2018; 98 ():145-151.
Chicago/Turabian StyleJ.V. Silveira; J.V.B. Moura; C. Luz-Lima; P.T.C. Freire; A.G. Souza Filho. 2018. "Laser-induced thermal effects in hexagonal MoO3 nanorods." Vibrational Spectroscopy 98, no. : 145-151.
This paper reports the study of the metastable hexagonal molybdenum oxide (h-MoO3) rods by looking at the vibrational, structural and morphological properties. The MoO3 as-synthesized rods were prepared by the precipitation method and characterized by X-ray diffraction, Raman spectroscopy and scanning electron microscopy, revealing a hexagonal phase and submicrometric size of the MoO3. The vibrational modes of the h-MoO3 were calculated by density-functional perturbation theory (DFPT) and used by first time to do the signature of the experimentally observed Raman modes, filling a gap in this field. Experimental temperature-dependent Raman spectroscopy study was carried out on h-MoO3 rods and pointed out to a phase transition in the 675-690 K temperature range. This phase transition was confirmed by scanning electron microscopy that was used to analyze the morphological changes in the MoO3 samples during the heating cycle. Temperature-dependent Raman data analysis combined with DFT calculations allowed us to confirm the mechanism that underlies the stability loss of the hexagonal phase at the critical temperature and to correlate the wavenumber difference of two specific Raman bands with the real temperature of the sample.
J.V.B. Moura; J.V. Silveira; J.G. Da Silva Filho; A.G. Souza Filho; C. Luz-Lima; P.T.C. Freire. Temperature-induced phase transition in h-MoO3: Stability loss mechanism uncovered by Raman spectroscopy and DFT calculations. Vibrational Spectroscopy 2018, 98, 98 -104.
AMA StyleJ.V.B. Moura, J.V. Silveira, J.G. Da Silva Filho, A.G. Souza Filho, C. Luz-Lima, P.T.C. Freire. Temperature-induced phase transition in h-MoO3: Stability loss mechanism uncovered by Raman spectroscopy and DFT calculations. Vibrational Spectroscopy. 2018; 98 ():98-104.
Chicago/Turabian StyleJ.V.B. Moura; J.V. Silveira; J.G. Da Silva Filho; A.G. Souza Filho; C. Luz-Lima; P.T.C. Freire. 2018. "Temperature-induced phase transition in h-MoO3: Stability loss mechanism uncovered by Raman spectroscopy and DFT calculations." Vibrational Spectroscopy 98, no. : 98-104.
In this study, we report the antibacterial activity and modulation of antibiotic activity by Fe2(MoO4)3 microstructures obtained by the hydrothermal route without use of surfactants or organic additives. This material was characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM) images. The XRD pattern showed that the Fe2(MoO4)3 crystallize in a monoclinic structure without secondary phases. Raman spectroscopy confirms the formation of Fe2(MoO4)3. SEM images show that the Fe2(MoO4)3 obtained have ball-of-yarn shaped morphology. In the antibacterial assays, strains of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were assayed by microdilution method to evaluate the antibacterial and modulatory-antibiotic activity with antibiotics as gentamicin, norfloxacin and imipenem. Against all bacteria, the Minimum Inhibitory Concentration (MIC) was Fe2(MoO4)3 ≥ 1024 μg/mL. This high MIC result must be associated with the fact of the iron be an essential microelement to the bacterial growth. However, when the Fe2(MoO4)3 was assayed in association with the antibiotics was observed an antagonistic effect demonstrated by an enhance of the MIC. This fact is associated directly with the pro-oxidative properties of metallic oxides. These compounds enhance the production of free radicals, as H2O2 and superoxide ions that can affect the cell structures as cell membrane and cell wall. Other effect is associated with the possible coordination of the metal, performing bonds with the chemical structure of the antibiotics, reducing their activity. Our results indicated that nanocompounds as Fe2(MoO4)3 can not be used as antimicrobial products for clinical usage, neither directly and neither in association with antibiotics.
T.S. Freitas; F.S. Oliveira; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; J.V.B. Moura; C. Luz-Lima; B.C. Viana; J.H. Da Silva; P.T.C. Freire; H.D.M. Coutinho. Modulation of antibiotic effect by Fe2(MoO4)3 microstrutures. European Journal of Pharmaceutical Sciences 2018, 123, 295 -300.
AMA StyleT.S. Freitas, F.S. Oliveira, R.P. Cruz, R.L.S. Pereira, A.R.P. Silva, J.V.B. Moura, C. Luz-Lima, B.C. Viana, J.H. Da Silva, P.T.C. Freire, H.D.M. Coutinho. Modulation of antibiotic effect by Fe2(MoO4)3 microstrutures. European Journal of Pharmaceutical Sciences. 2018; 123 ():295-300.
Chicago/Turabian StyleT.S. Freitas; F.S. Oliveira; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; J.V.B. Moura; C. Luz-Lima; B.C. Viana; J.H. Da Silva; P.T.C. Freire; H.D.M. Coutinho. 2018. "Modulation of antibiotic effect by Fe2(MoO4)3 microstrutures." European Journal of Pharmaceutical Sciences 123, no. : 295-300.
J.V.B. Moura; G.S. Pinheiro; J.V. Silveira; P.T.C. Freire; B.C. Viana; C. Luz-Lima. NaCe(MoO4)2 microcrystals: Hydrothermal synthesis, characterization and photocatalytic performance. Journal of Physics and Chemistry of Solids 2017, 111, 258 -265.
AMA StyleJ.V.B. Moura, G.S. Pinheiro, J.V. Silveira, P.T.C. Freire, B.C. Viana, C. Luz-Lima. NaCe(MoO4)2 microcrystals: Hydrothermal synthesis, characterization and photocatalytic performance. Journal of Physics and Chemistry of Solids. 2017; 111 ():258-265.
Chicago/Turabian StyleJ.V.B. Moura; G.S. Pinheiro; J.V. Silveira; P.T.C. Freire; B.C. Viana; C. Luz-Lima. 2017. "NaCe(MoO4)2 microcrystals: Hydrothermal synthesis, characterization and photocatalytic performance." Journal of Physics and Chemistry of Solids 111, no. : 258-265.
This study reports the antibacterial properties and modulation analysis of antibiotic activity by β-Ag2MoO4 microcrystals as well as their structural and vibrational characterization. The silver molybdate was obtained by the conventional hydrothermal method, and the structural, vibrational and morphological properties of the sample were determined using X-ray diffraction, Raman spectroscopy and scanning electron microscopy images. β-Ag2MoO4 microcrystals obtained show spinel-type cubic structure (Fd-3m) with irregular shapes. The evaluation of antibacterial and modulatory-antibiotic activity was performed using the microdilution method to determine the Minimum Inhibitory Concentration (MIC) of the β-Ag2MoO4 and antibiotics alone and associated with the silver molybdate. The β-Ag2MoO4 modulates the antibiotic activity against all bacteria assayed in a synergistic (as the norfloxacin and gentamicin against S. aureus and gentamicin against E. coli) or an antagonistic form (as the norfloxacin against E.coli and P. aeruginosa). The reversion of antibiotic resistance by combinations with Ag2MoO4 could be a novel strategy to combat infections caused by multiple drug resistance (MDR) pathogens. Our results indicate that these silver molybdates present a clinically relevant antibacterial activity and enhanced the antibiotic activity of some antibiotics against MDR strain of S. aureus and E. coli, being an interesting alternative to combat antibiotic-resistant bacterial infectious agents.
J.V.B. Moura; T.S. Freitas; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; A.T.L. Santos; J.H. da Silva; C. Luz-Lima; Paulo De Tarso Cavalcante Freire; Henrique Coutinho. β-Ag2MoO4 microcrystals: Characterization, antibacterial properties and modulation analysis of antibiotic activity. Biomedicine & Pharmacotherapy 2016, 86, 242 -247.
AMA StyleJ.V.B. Moura, T.S. Freitas, R.P. Cruz, R.L.S. Pereira, A.R.P. Silva, A.T.L. Santos, J.H. da Silva, C. Luz-Lima, Paulo De Tarso Cavalcante Freire, Henrique Coutinho. β-Ag2MoO4 microcrystals: Characterization, antibacterial properties and modulation analysis of antibiotic activity. Biomedicine & Pharmacotherapy. 2016; 86 ():242-247.
Chicago/Turabian StyleJ.V.B. Moura; T.S. Freitas; R.P. Cruz; R.L.S. Pereira; A.R.P. Silva; A.T.L. Santos; J.H. da Silva; C. Luz-Lima; Paulo De Tarso Cavalcante Freire; Henrique Coutinho. 2016. "β-Ag2MoO4 microcrystals: Characterization, antibacterial properties and modulation analysis of antibiotic activity." Biomedicine & Pharmacotherapy 86, no. : 242-247.
This study reports on the effect of high hydrostatic pressure on the vibrational spectra of Fe2(MoO4)3 microcrystals using Raman scattering in combination with a membrane diamond-anvil cell. The ferric molybdate was obtained by the conventional hydrothermal method, and the structural and morphological properties of the sample were characterized using additionally X-ray diffraction, scanning electron microscopy, as well as energy dispersive spectroscopy. The X-ray diffraction measurements have shown that the crystals have a monoclinic structure. At pressures higher than 4.8 GPa, the disappearance of external modes was observed, suggesting that pressure has induced a breakdown in the translational symmetry of the crystal system. The high-pressure amorphous phase is reversible and attributed to an incomplete crystal-amorphous transformation.
J.V.B. Moura; G.S. Pinheiro; Paulo De Tarso Cavalcante Freire; J. Mendes Filho; G.D. Saraiva; B.C. Viana; C. Luz-Lima. High-pressure Raman scattering on Fe 2 (MoO 4 ) 3 microcrystals obtained by a hydrothermal method. Vibrational Spectroscopy 2016, 87, 88 -93.
AMA StyleJ.V.B. Moura, G.S. Pinheiro, Paulo De Tarso Cavalcante Freire, J. Mendes Filho, G.D. Saraiva, B.C. Viana, C. Luz-Lima. High-pressure Raman scattering on Fe 2 (MoO 4 ) 3 microcrystals obtained by a hydrothermal method. Vibrational Spectroscopy. 2016; 87 ():88-93.
Chicago/Turabian StyleJ.V.B. Moura; G.S. Pinheiro; Paulo De Tarso Cavalcante Freire; J. Mendes Filho; G.D. Saraiva; B.C. Viana; C. Luz-Lima. 2016. "High-pressure Raman scattering on Fe 2 (MoO 4 ) 3 microcrystals obtained by a hydrothermal method." Vibrational Spectroscopy 87, no. : 88-93.
C. Luz-Lima; J.A. Borges; J.V.B. Moura; G.S. Pinheiro; B.C. Viana; J. Mendes-Filho; P.T.C. Freire. α-l-Glutamic acid under high pressure: Phase transitions studied by Raman spectroscopy. Vibrational Spectroscopy 2016, 86, 343 -349.
AMA StyleC. Luz-Lima, J.A. Borges, J.V.B. Moura, G.S. Pinheiro, B.C. Viana, J. Mendes-Filho, P.T.C. Freire. α-l-Glutamic acid under high pressure: Phase transitions studied by Raman spectroscopy. Vibrational Spectroscopy. 2016; 86 ():343-349.
Chicago/Turabian StyleC. Luz-Lima; J.A. Borges; J.V.B. Moura; G.S. Pinheiro; B.C. Viana; J. Mendes-Filho; P.T.C. Freire. 2016. "α-l-Glutamic acid under high pressure: Phase transitions studied by Raman spectroscopy." Vibrational Spectroscopy 86, no. : 343-349.
This paper reports the temperature-dependent study of β-Ag2MoO4 micro-crystals using Raman spectroscopy. The micro-crystals were prepared by the hydrothermal method, and lattice dynamic calculations based on the density-functional theory (DFT) were used to assign the Raman modes observed in the spectrum and to support the understanding of the mechanism driving the vibrational changes undergone by β-Ag2MoO4. The effect of the temperature on the vibrational properties of the β-Ag2MoO4 has been investigated in the temperature range from 300 to 850 K. The Raman data indicated that the crystal exhibits two temperature-induced phase transformations. One of them was assigned to a first-order phase transition (from cubic to unknown symmetry) occurring at about 541 K, connected with some disorder in the MoO4 tetrahedron, therefore, leading to tiltings and/or rotations of the MoO4 units, as revealed by changes in the Raman spectra. The second phase transition was observed at about 700 K, thus leading the crystal to change its symmetry from the unknown phase to the same cubic room temperature symmetry (reentrant phase transition).
J.V.B. Moura; J.G. Da Silva Filho; P.T.C. Freire; C. Luz-Lima; G.S. Pinheiro; B.C. Viana; A.G. Souza-Filho; G.D. Saraiva. Phonon properties of β-Ag2MoO4: Raman spectroscopy and ab initio calculations. Vibrational Spectroscopy 2016, 86, 97 -102.
AMA StyleJ.V.B. Moura, J.G. Da Silva Filho, P.T.C. Freire, C. Luz-Lima, G.S. Pinheiro, B.C. Viana, A.G. Souza-Filho, G.D. Saraiva. Phonon properties of β-Ag2MoO4: Raman spectroscopy and ab initio calculations. Vibrational Spectroscopy. 2016; 86 ():97-102.
Chicago/Turabian StyleJ.V.B. Moura; J.G. Da Silva Filho; P.T.C. Freire; C. Luz-Lima; G.S. Pinheiro; B.C. Viana; A.G. Souza-Filho; G.D. Saraiva. 2016. "Phonon properties of β-Ag2MoO4: Raman spectroscopy and ab initio calculations." Vibrational Spectroscopy 86, no. : 97-102.