Biofilm-associated infections are a public health concern especially in the context of healthcare-associated infections such as catheter-related bloodstream infections (CRBSIs). We evaluated the biofilm formation and antimicrobials...
moreBiofilm-associated infections are a public health concern especially in the context of healthcare-associated infections such as catheter-related bloodstream infections (CRBSIs). We evaluated the biofilm formation and antimicrobials resistance (AMR) of Enterobacter cloacae complex and Candida parapsilosis co-isolated from a CRBSI patient. Antimicrobial susceptibility of central venous catheters (CVCs) and hemoculture (HC) isolates was evaluated, including whole genome sequencing (WGS) resistome analysis and evaluation of gene expression to obtain insight into their AMR determinants. Crystal violet assay was used to assess dual biofilm biomass and microscopy was used to elucidate a microorganism’s distribution within biofilms assembled on different materials. Bacteria were multidrug-resistant including resistance to colistin and beta-lactams, likely linked to the mcr-9-like phosphoethanolamine transferase and to an ACT family cephalosporin-hydrolyzing class C beta-lactamase, respectiv...
Encapsulated forms of α-tocopherol into β-cyclodextrin and zein carriers for colour stability and shelf-life improvement of beverages.
Pea protein was successfully encapsulated into a lipophilic carrier through PGSS®. HPT-scCO2of pea protein has enabled higher foam stability.
Introdução: A identificação de cristais no líquido sinovial é feita habitualmente através do exame micros-cópico com luz ordinária, luz compensada e algumas colorações. No entanto, dadas as suas pequenas di-mensões e diminutas...
moreIntrodução: A identificação de cristais no líquido sinovial é feita habitualmente através do exame micros-cópico com luz ordinária, luz compensada e algumas colorações. No entanto, dadas as suas pequenas di-mensões e diminutas concentrações no líquido sinovial, por vezes nem mesmo após centrifugação estes se conseguem identificar utilizando esses métodos. Objectivos: Analisar a detecção de cristais no líquido sinovial de doentes com monoartrite não infeccio-sa, sem história de traumatismo ou patologia osteoarticular antecedente, em microscopia de luz polari-zada e em microscopia electrónica. Material e Métodos: Foram avaliadas amostras de líquido sinovial de doentes com monoartrite não in-fecciosa, sem história de traumatismo ou patologia osteoarticular prévia. Os líquidos sinoviais obtidos fo-ram observados numa fase inicial no microscópio de luz polarizada e com a coloração com vermelho de alizarina. Posteriormente, analisámos as mesmas amostras por microscopia electrónica de tran...
Electrodeposition of zinc based films in constant and pulsed regimes of electrolysis was performed and the obtained electrodeposits were examined by field emission-scanning electron microscopy. The electrodeposition is one of the most...
moreElectrodeposition of zinc based films in constant and pulsed regimes of electrolysis was performed and the obtained electrodeposits were examined by field emission-scanning electron microscopy. The electrodeposition is one of the most effective methods for the synthesis of nanostructures of metals and semiconductors with desired morphology and characteristics for many technological applications [1]. There are several variables that may be tailored specifically the electrolysis regime, the bath composition, pH, solution stirring and temperature [2]. Most of the depositions that will be discussed here were performed at acidic or near neutral solutions. Electrodeposition by pulse current, is a very versatile method, since more experimental conditions can be changed such as current density, duty cycle and pulse frequency with huge effect on the deposits characteristics: composition, structure, morphology and porosity [3]. The electrodeposits of zinc on different metals, namely steel, have special relevance due to their anticorrosive properties by the formation of passive layers in contact with air, and in aqueous solution. The corrosive resistance of the films is strongly connected to the morphological characteristics of metallic films that could be tailored by using additives in the bath, such as surfactants or oxide nanoparticles. The adsorption of surfactants aggregates or adsorption of nanoparticles onto electrodes can have large effects on the kinetics of the electron transfer and consequently on the electrodeposition process. The effect on the electron transfer rates includes blocking of the active sites by the surfactants, and electrostatic interactions between electroactive species and adsorbed surfactants [4]. Due to those effects it is possible to modify the growth mode of the crystals and tailor the morphology and structure of the electrodeposits. In a previous work cationic, anionic and non-ionic surfactants have been used for studying the effect of the charge of headgroups on the electrodeposition process. It was conclude that the use of the surfactant leads to a decrease in the grain size and changes in the film’s morphology and the zinc texture [5]. Due to the co-deposition process of oxide nanoparticles and metallic film, metal matrix nanocomposites can be successfully prepared [6]. It is expected that by electrolysis of plating solutions in which micron or sub-micron size particles are suspended, it is possible to obtain solid materials with improved and/or combined properties, which make them interesting for applications such as environmental remediation. Composites containing occluded TiO2 particles are suitable materials, due to the semiconducting properties of TiO2, with applications as photocatalysts, particularly in the treatment of polluted water. In recent years research efforts are underway to develop more powerful methods than those currently applied in wastewater treatment. Thus, the search for new efficient methods for the degradation of pollutants is a priority. Electrochemical and photoelectrochemical degradation can be suitable and low-cost alternatives to those used presently [7]. The implementation of these methods is closely linked with the development of stable, nonpollutant, cheap and electrocatalytic/ photocatalytic electrode materials. Composite electrodes of Ti/Zn-TiO2 have been successfully prepared by us in recent years [8]. In addition, we have tried with little success the implementation of these electrodes in the pharmaceutical degradation by photoassisted electrochemical processes. To improve the photo ability of matrix we have transformed the Zn matrix into wurtzite-structured ZnO. With a wide band gap (3.35 eV) [9], ZnO has been used as an environmental photocatalyst for water purification with the aid of artificial light source. Among the techniques used for the oxidation of Zn films, heat treatment in air seems to be the simplest due to relative low melting point of Zn. The conversion process depends on the crystallinity and orientation of as-deposited Zn. We have already achieved the formation of nanocrystalline ZnO films with higher surface area [10] and, successfully used this strategy to prepare Ti/ZnO-TiO2 photoelectrodes for the degradation of the AO7 dye and ibuprofen present in Current Microscopy Contributions to Advances in Science and Technology (A. Mendez-Vilas, Ed.)
The increase in bacterial resistance to antibiotics has led researchers to find new compounds or find combinations between different compounds with potential antibacterial action and with the ability to prevent the development of...
moreThe increase in bacterial resistance to antibiotics has led researchers to find new compounds or find combinations between different compounds with potential antibacterial action and with the ability to prevent the development of antibiotic resistance. Polyoxotungstates (POTs) are inorganic clusters that may fulfill that need, either individually or in combination with antibiotics. Herein, we report the ability of the polyoxotungstates (POTs) with Wells-Dawson P2W18, P2W17, P2W15, and Preyssler P5W30 type structures to differently affect Gram-negative and Gram-positive microorganisms, either susceptible or resistant to antibiotics. The compound P5W30 showed the highest activity against the majority of the tested bacterial strains in comparison with the other tested POTs (P2W15, P2W17 and P2W18) that did not show inhibition zones for the Gram-negative bacteria, A. baumanii I73775, E. coli DSM 1077, E. coli I73194, K. pneumoniae I7092374, and P. aeruginosa C46281). Generally, the resu...
In this work, the water order and dynamics in hydrated films of flat asymmetric cellulose acetate (CA)/silica, CA/SiO2, and hybrid membranes, covering a wide range of nanofiltration (NF) and ultrafiltration (UF) permeation properties,...
moreIn this work, the water order and dynamics in hydrated films of flat asymmetric cellulose acetate (CA)/silica, CA/SiO2, and hybrid membranes, covering a wide range of nanofiltration (NF) and ultrafiltration (UF) permeation properties, were characterised by deuterium nuclear magnetic resonance (DNMR) relaxation. The range of NF/UF characteristics was attained by subjecting three CA/SiO2 membranes, prepared from casting solutions with different acetone/formamide ratios to drying post-treatments of solvent exchange and conditioning with surfactant mixtures. Post-treated and pristine CA/SiO2 membranes were characterised in terms of hydraulic permeability, selective permeation properties and molecular weight cut-off. These results were correlated with the DNMR relaxation findings. It was found that the post-treatment by solvent exchange caused membrane shrinkage that led to very different permeation characteristics and a significant enhancement of the DNMR relaxation observables. In cont...
Aluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by...
moreAluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by laser alloying. Sound, defect-free coatings are produced, provided that proper surface treatment techniques are used. The composition of the surface layers was Al-37.6 (±3) wt.% Nb and their microstructure is formed of dendrites of Al3Nb and a small volume fraction of interdendritic α-Al. The Vickers microhardness of the surface alloys is high, owing to the large amount and fineness of Al3Nb intermetallic compound. It varies from 480 to 650 HV, depending on the volume fraction and dendrite arm spacing of Al3Nb dendrites. Despite the brittleness of Al3Nb the coatings did not show any tendency to crack, probably because of the presence of the thin interdendritic film of ductile α-Al, which allows for a better accommodation of the generated stresses, and stops the propagation of microcracks that may develop in the intermetallic compound particles.Aluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by laser alloying. Sound, defect-free coatings are produced, provided that proper surface treatment techniques are used. The composition of the surface layers was Al-37.6 (±3) wt.% Nb and their microstructure is formed of dendrites of Al3Nb and a small volume fraction of interdendritic α-Al. The Vickers microhardness of the surface alloys is high, owing to the large amount and fineness of Al3Nb intermetallic compound. It varies from 480 to 650 HV, depending on the volume fraction and dendrite arm spacing of Al3Nb dendrites. Despite the brittleness of Al3Nb the coatings did not show any tendency to crack, probably because of the presence of the thin interdendritic film of ductile α-Al, which allows for a better accommodation of the generated stresses, and stops the propagati...
Abstract Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and biofilm formation. In this study the effect of the nanocomposite Moroccan propolis extract / MNPs acting against methicillin resistant strains...
moreAbstract Magnetite nanoparticles (MNPs) have been evaluated for inhibiting microbial growth and biofilm formation. In this study the effect of the nanocomposite Moroccan propolis extract / MNPs acting against methicillin resistant strains of Staphylococcus aureus (MRSA) was evaluated. Chemical composition of propolis was established by pyrolysis coupled to gas chromatography and mass spectrometry method (pyrolysis GC/MS). MNPs were obtained through the co-precipitation method. The fabricated nanostructure was characterized by X-ray Diffraction (DRX), Transmission Electron Microscopy (TEM), and Fourier Transform-Infrared Spectroscopy (FTIR). TEM of MNPs provided a particle average size of 15 nm, FTIR spectral analysis enabled a fast way of identification of MNPs, attesting the occurrence of the different combinations. The use of MNPs loaded with propolis and the antibiotic chloramphenicol at Minimum Inhibitory Concentration (MIC) value inhibited the bacterial growth of MSSA (methicillin susceptible strain of S. aureus) and MRSA strains. After the treatment with MNPs-OA-P-CLo nanocomposite (MNPs with oleic acid, propolis and chloramphenicol), the disruption of the bacterial cell was observed by TEM. The combination of propolis and chloramphenicol in free form at MIC value largely impaired both MSSA and MRSA strains as, after 2 h of treatment, no viable cells of MRSA 2 and MRSA 16 were recovered. Hence, the results elucidated a new antibacterial nanocomposite synthesis, for possible applications as prospective nanoantibacterial agents or drug carriers.
Abstract Zinc (Zn) has been proposed as an alternative metallic biodegradable material to support transient wound-healing processes. Once a Zn piece is implanted inside the organism the degradation will depend upon the physiological...
moreAbstract Zinc (Zn) has been proposed as an alternative metallic biodegradable material to support transient wound-healing processes. Once a Zn piece is implanted inside the organism the degradation will depend upon the physiological surrounding environment. This, by modulating the composition of the surface layers formed on Zn devices, will govern the subsequent interactions with the surrounding living cells (e.g. biocompatibility and/or antifungal behaviour). In silico simulation of an implanted Zn piece at bone-muscle interface or inside the bone yielded the preferential precipitation of simonkolleite or zincite, respectively. To study the impact of these surface layers in the in vitro behaviour of Zn biomaterials, simonkolleite and zincite where synthesised. The successful production of simonkolleite or zincite was confirmed by an extensive physicochemical characterization. An in vitro layer formed on the top of these surface layers revealed that simonkolleite was rather inert, while zincite yielded a complex matrix containing hydroxyapatite, an important bone analogue. When analysing the “anti-biofilm” activity simonkolleite stood out for its activity against an important pathogenic fungi involved in implant-device infections, Candida albicans. The possible physiological implications of these findings are discussed.
In parks, ornamental waters of easy access and populated with animals are quite attractive to children and yet might hide threats to human health. The present work focuses on the microbiota of the ornamental waters of a Lisboa park,...
moreIn parks, ornamental waters of easy access and populated with animals are quite attractive to children and yet might hide threats to human health. The present work focuses on the microbiota of the ornamental waters of a Lisboa park, characterized during 2015. The results show a dynamic microbiota integrating human pathogens such as Klebsiella pneumoniae, Aeromonas spp. and Enterobacter spp., and also antibiotic resistant bacteria. K. pneumoniae and Aeromonas spp. were present as planktonic and biofilm organized bacteria. In vitro K. pneumoniae and Aeromonas spp. showed an enhanced ability to assemble biofilm at 25 °C than at 37 °C. Bacteria recovered from biofilm samples showed an increased antibiotic resistance compared to the respective planktonic counterparts.
Aluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by...
moreAluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by laser alloying. Sound, defect-free coatings are produced, provided that proper surface treatment techniques are used. The composition of the surface layers was Al-37.6 (±3) wt.% Nb and their microstructure is formed of dendrites of Al3Nb and a small volume fraction of interdendritic α-Al. The Vickers microhardness of the surface alloys is high, owing to the large amount and fineness of Al3Nb intermetallic compound. It varies from 480 to 650 HV, depending on the volume fraction and dendrite arm spacing of Al3Nb dendrites. Despite the brittleness of Al3Nb the coatings did not show any tendency to crack, probably because of the presence of the thin interdendritic film of ductile α-Al, which allows for a better accommodation of the generated stresses, and stops the propagation of microcracks that may develop in the intermetallic compound particles.Aluminum-niobium alloys present considerable strength and hardness, being promising materials for structural applications and as coatings. This paper reports results of a study on the structure and properties of Al-Nb coatings produced by laser alloying. Sound, defect-free coatings are produced, provided that proper surface treatment techniques are used. The composition of the surface layers was Al-37.6 (±3) wt.% Nb and their microstructure is formed of dendrites of Al3Nb and a small volume fraction of interdendritic α-Al. The Vickers microhardness of the surface alloys is high, owing to the large amount and fineness of Al3Nb intermetallic compound. It varies from 480 to 650 HV, depending on the volume fraction and dendrite arm spacing of Al3Nb dendrites. Despite the brittleness of Al3Nb the coatings did not show any tendency to crack, probably because of the presence of the thin interdendritic film of ductile α-Al, which allows for a better accommodation of the generated stresses, and stops the propagati...
Indian miniature painting on silk represents an important cultural object [1], emerged in Rajasthan around the 17 th century. Traditionally, these types of paintings were made from local pigments removed directly from minerals of...
moreIndian miniature painting on silk represents an important cultural object [1], emerged in Rajasthan around the 17 th century. Traditionally, these types of paintings were made from local pigments removed directly from minerals of Rajasthan province and handmade to be painted with fine brushes to enable the presence of details, which increase their value. In this study, pictorial materials were largely characterized by means of EDXRF to provide information on the nowadays-employed materials in order to make a comparison with the traditionally used ones [2]. Whenever EDXRF analysis showed limitations in the miniature characterization, Raman spectroscopy was used as complementary technique. Chemical composition of small glittering grains employed on golden and silver areas and on the frame was determined by SEM-EDS. The carrier was identified by Raman spectroscopy as being made of silk from Bombyx mori, and revealed a particular fibers structure composition characteristic of a specific...
In clinical practice crystal identification in synovial fluid is made by polarized light microscopy and with some specific stainings. Nevertheless, sometimes we are unable to identify crystals by these means, either because they are too...
moreIn clinical practice crystal identification in synovial fluid is made by polarized light microscopy and with some specific stainings. Nevertheless, sometimes we are unable to identify crystals by these means, either because they are too small or because they are widespread on the fluid. To compare the identification of crystals in synovial fluid from patients with non-infectious monoarthritis but no history of local trauma or articular disease, using polarized light and electronic microscopy. We analized synovial fluid samples from patients with non-infectious monoarthritis and no history of local trauma or articular disease. First we used a polarized light microscope and alizarin red staining. Later we used conventional transmission electron microscopy and energy dispersive spectroscopy, in order to identify and characterize crystals. Fourty-five samples from 23 synovial fluids were analyzed. Under polarized light microscopy we identified crystals on 11 samples: 3 with calcium pyro...
Al–Nb alloys present considerable strength and hardness, being promising materials for structural applications and for coatings. This paper reports results of a study of the structure and properties of Al–Nb surface alloys produced by...
moreAl–Nb alloys present considerable strength and hardness, being promising materials for structural applications and for coatings. This paper reports results of a study of the structure and properties of Al–Nb surface alloys produced by laser alloying. Surface alloys were produced by a two-step process: firstly, commercial purity Al substrates were alloyed with Nb by injecting an Al–25 wt.% Nb powder
Hybrid lipid-polymer particles are gaining increasing interest to be applied as drug delivery systems due to their greater stability in biological fluids and enhanced cellular uptake of drugs. However, a major drawback is the fact that...
moreHybrid lipid-polymer particles are gaining increasing interest to be applied as drug delivery systems due to their greater stability in biological fluids and enhanced cellular uptake of drugs. However, a major drawback is the fact that these particles are usually produced through techniques that use organic solvents. This work studies the possibility of producing for the first time hybrid particles composed by lipid multicores enveloped in a polymeric layer through Particles from Gas Saturated Solutions (PGSS(®)), without using organic solvents. An oil-in-water emulsion, composed by Gelucire 43/01™ (GEL) as the discontinuous phase and by an aqueous polyethylene glycol 4000 (PEG) solution as the continuous phase, was successfully precipitated by PGSS(®). Operating conditions that ensured the stability of the CO2 saturated emulsion were previously evaluated. The resulting PEG-GEL particles present a spherical-like morphology constituted by several lipid cores encapsulated into a polymeric shell. The applicability of these structured particles to be used as drug delivery system (DDS) was studied by using ketoprofen, a nonsteroidal anti-inflammatory drug (NSAID), as model drug. The particles provided an initial burst release of the drug due to the progressive dissolution of the external layer of PEG, followed by a controlled release of the NSAID from the GEL cores.
ABSTRACT In this work we used medium and high fluence Cr implantation, 5×1016 and 5×1017/cm2 in an attempt to promote the formation of a Mg–Cr surface system with enhanced corrosion resistance, in particular under neutral and acid...
moreABSTRACT In this work we used medium and high fluence Cr implantation, 5×1016 and 5×1017/cm2 in an attempt to promote the formation of a Mg–Cr surface system with enhanced corrosion resistance, in particular under neutral and acid conditions. It is also the aim of this work to contribute to the study of the influence and role of the implanted ions in the corrosion progress and mechanisms. Unimplanted and Cr implanted magnesium surfaces were submitted to accelerated corrosion tests by the immersion technique. Concentration depth profiles of the implanted ions were obtained by use of Rutherford backscattering spectrometry (RBS). Information about the H and O contents and depth profiles were obtained by, respectively, elastic recoil detection and RBS, before and after immersion of the unimplanted and implanted surfaces in a 3 wt.% NaCl solution saturated with Mg(OH)2, for different periods of time. The elemental composition and surface distribution of the corroded surfaces were characterised by RBS and proton induced X-ray emission maps obtained with an ion microprobe, and complemented with electron microprobe analysis. Morphology of the affected surfaces was accessed by scanning electron microscopy.
Cr or Mn must be used in stoichiometric amounts and are often accompanied by the formation of toxic waste products, which can be deleterious during the work-up procedure, resulting in tricky product isolation, and rendering impossible the...
moreCr or Mn must be used in stoichiometric amounts and are often accompanied by the formation of toxic waste products, which can be deleterious during the work-up procedure, resulting in tricky product isolation, and rendering impossible the reusability of the catalyst. The use of hypervalent iodine reagents such as Dess–Martin periodinane (DMP) presents some problems, however, advances have been achieved with the development of various 2-iodoxybenzoic acid (IBX, a DMP precursor) derivatives which have improved solubility, are non-explosive, and/or are recyclable. [1e]
ABSTRACT A nano-sized Magnesia–Zirconia (nano-MgO–ZrO2) catalyst was prepared by a simple ultradilution coprecipitation method and by using inexpensive precursors. The nano-MgO–ZrO2 was extensively characterized by SIMS together with...
moreABSTRACT A nano-sized Magnesia–Zirconia (nano-MgO–ZrO2) catalyst was prepared by a simple ultradilution coprecipitation method and by using inexpensive precursors. The nano-MgO–ZrO2 was extensively characterized by SIMS together with other analytical techniques such as X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nano-MgO–ZrO2 catalyst proved to be very efficient for the reduction of carbonyl compounds and multicomponent reactions under mild reaction conditions. The recyclability and reusability of the nano-MgO–ZrO2 catalyst has been tested.
ABSTRACTThe microstructures of tungsten, molybdenum and copper wires used as Langmuir probes at ISTTOK edge plasma have been investigated. The probes cross-sections evidenced extensive grain growth, intergranular bubbles and increased...
moreABSTRACTThe microstructures of tungsten, molybdenum and copper wires used as Langmuir probes at ISTTOK edge plasma have been investigated. The probes cross-sections evidenced extensive grain growth, intergranular bubbles and increased hardness at the plasma exposed regions. Internal surfaces of large bubbles exhibited slip bands resulting from plastic deformation induced by high H2 pressure. Elastic recoil detection analysis was used to measure H concentration profiles. The present results suggest that H2 bubble formation in first wall components under long-term high thermal loads should be closely monitored in nuclear fusion devices. Strategies for H damage mitigation are proposed and discussed.
The objects of this study are various local charters (cartas de foral, in Portuguese) granted by Dom Manuel I, King of Portugal (1495-1521), which substituted for medieval ones and were intended to achieve an administrative unification....
moreThe objects of this study are various local charters (cartas de foral, in Portuguese) granted by Dom Manuel I, King of Portugal (1495-1521), which substituted for medieval ones and were intended to achieve an administrative unification. These are luxuriously illuminated manuscripts, and our study aims at obtaining a better understanding of the gilding and silvering techniques applied to the parchments, in which the forais were written, between 1500 and 1520. The combined use of microscopy and X-ray spectroscopy analyses allowed us to identify the vestigial materials used for making the parchments, including products such as salt (NaCl), lime (CaO), pumice stone (SiO2+Al2O3), and chalk (CaCO3). Chalk was employed as a whitening agent to give the parchment its final color and opacity. Shell-gold and shell-silver mixed in with animal glue or gum binding media were directly applied on type 1 and 3 forais, while very thin gold leaves (<1 µm) were applied over lead-based tempera ground...
The modelling and development of a lipophilic natural pink colourant derived from Opuntia spp. was studied using a green technology – PGSS® (Particles from Gas-Saturated Solutions).
ABSTRACT For the first time, gas-filled microparticles were successfully prepared using a supercritical fluid based technology. Low molecular weight perfluorcarbon (PFC) gases, C 3 F 8 or C 4 F 8 , have been encapsulated into Gelucire ®...
moreABSTRACT For the first time, gas-filled microparticles were successfully prepared using a supercritical fluid based technology. Low molecular weight perfluorcarbon (PFC) gases, C 3 F 8 or C 4 F 8 , have been encapsulated into Gelucire ® 50/13 (lipid-based carrier: polyethylene glycol glycerides), using PGSS ® (Particles from Gas Saturated Solution) technique. Particles were produced from the fast expansion of the melted lipid carrier saturated with a mixture of (CO 2 + PFC). The presence of the gas into the produced microparticles was verified by Nuclear Magnetic Resonance (NMR) analysis of fluorine atom. The effect of carrier to PFC mass ratio and PFC structure on the entrapment efficiency of the PFC gas into the particles was evaluated at fixed at 8.5 MPa and 353 K. These parameters were fixed in a preliminary study according to the morphology, size and flowability of the particles. The stability of encapsulated C 4 F 8 in microparticles showed to be higher than C 3 F 8 ; it was determined to be 2 h, at room conditions at the optimized carrier: PFC mass ratio of 30:1.
ABSTRACT The formulation of S-(+)-ibuprofen as a model water-insoluble drug in different carrier materials (poloxamers, gelucire and glyceryl monostearate, GMS) by Particles from Gas Saturated Solutions (PGSS) technique has been studied....
moreABSTRACT The formulation of S-(+)-ibuprofen as a model water-insoluble drug in different carrier materials (poloxamers, gelucire and glyceryl monostearate, GMS) by Particles from Gas Saturated Solutions (PGSS) technique has been studied. Porous, spherical particles of 50-200 mu m have been obtained with encapsulation efficiencies up to 90%. Differential scanning calorimetry assays reveal modifications on the structure of the material, with formation of a solid solution in experiments with poloxamer carriers, and formation of solid dispersions with a possible reduction of the crystallinity of the carrier in experiments with GMS. Drug release tests in simulated gastric and intestinal fluids have been performed. Formulations with poloxamer carrier materials provided an increased solubility of ibuprofen in the gastrointestinal fluids, with a very fast release and dissolution of this compound, while gelucire and GMS carriers did not improve the solubility of ibuprofen, but provided a slower, controlled release of the drug. PGSS-processed samples presented a superior performance over physical mixtures in terms of the solubility increase and the control of the release rate. These results show the wide possibilities and flexibility of the PGSS technique for the development of hybrid formulations of water-insoluble active compounds with hydrophilic or hydrophobic carrier materials, achieving either an increased, accelerated dissolution, or a slower, controlled delivery, depending on the choice of carrier materials.
Abstract Oregano (Origanum vulgare) essential oil (EO), besides its flavoring characteristics, is well known for its antioxidant, antimicrobial and anti-inflammatory properties, which make it a good alternative as food preservative from...
moreAbstract Oregano (Origanum vulgare) essential oil (EO), besides its flavoring characteristics, is well known for its antioxidant, antimicrobial and anti-inflammatory properties, which make it a good alternative as food preservative from natural origin. Furthermore, it has been reported that oregano EO can be used as a health promoting substance in the prevention of neurodegenerative disorders. However, EO can be easily degraded by light, oxygen and temperature and there is still a lack of an adequate protection system to improve its stability along processing. In the present study, oregano essential oil was impregnated in microspheres of different types of starch using SSI (supercritical solvent impregnation) with supercritical carbon dioxide (sc-CO2). This process is characterized by mild operating conditions and inert processing atmosphere, especially adequate for the formulation of EOs. The quality of the final product and process efficiency was evaluated by the antioxidant activity (AA) of the final product, determined according to the ORAC assay. Different processing conditions were studied, such as pressure (8–15 MPa), temperature (40–50 °C), impregnation time (3–24 h) and mass ratio of essential oil/starch (0.4–3). The SSI is a batch process and the influence of mode of depressurization was also analyzed. Industrial relevance The present study demonstrates that supercritical impregnation is an attractive process for the impregnation of natural matrices, such as starch granules, with essential oils (EOs), namely oregano essential oil. The mild operating conditions avoid EO degradation and the high diffusivity of supercritical CO2 in the solid matrix (starch) guarantees a deep impregnation of the EO and high antioxidant activity of the product, also during storage. Further, the process is easy to scale up for the production of potential health-promoting ingredients for the food industry.
... Study on selectivity of β-myrcene hydrogenation in high-pressure carbon dioxide catalysed by noble metal catalysts. ... The final composition of the reaction mixture is strongly dependent on the noble metal catalyst used for the...
more... Study on selectivity of β-myrcene hydrogenation in high-pressure carbon dioxide catalysed by noble metal catalysts. ... The final composition of the reaction mixture is strongly dependent on the noble metal catalyst used for the reaction. ...
ABSTRACT Biodiesel is a renewable fuel suitable to replace fossil fuel which can help to mitigate the carbon foot print of the transportation sector. Its price is still noncompetitive mainly due to high price of raw materials (vegetable...
moreABSTRACT Biodiesel is a renewable fuel suitable to replace fossil fuel which can help to mitigate the carbon foot print of the transportation sector. Its price is still noncompetitive mainly due to high price of raw materials (vegetable oils) and the costs of the processes. In order to find an efficient basic heterogeneous catalyst to replace the nowadays industrial caustic catalyst, a cheap CaO material was used to produce biodiesel using semi-refined rape seed oil (RSO). For the same catalyst the catalytic activity was tested with oleic acid acidified oil in order to simulate the use of low price materials with high activity. A linear decay of the Fatty Acid Methyl Ester (FAME) yield was observed, when oil acidity increases due to catalyst neutralization. The XRD and TG data showed that catalysts deactivation can be related with catalyst amorphization what can be related with soaps formation. The catalytic tests with acidic waste frying oil (WFO) showed that biodiesel can be produced over CaO catalyst from low value raw materials without significant deterioration of the catalytic performances.