Artigos - Físico Química - IQ

URI Permanente para esta coleçãohttps://hdl.handle.net/11449/25362

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Agora exibindo 1 - 20 de 1854

Wastewater sludge recycling: An efficient catalyst for photo-Fenton degradation of antibiotics and effluent disinfection
(2023-07-01) de Jesus, Jany H.F. ; Lima, Karla V.L. ; Hammer, Peter ; Nogueira, Raquel F.P. ; Universidade Estadual Paulista (UNESP)
An environmentally friendly strategy for recycling sewage sludge is proposed based on the thermal generation of a magnetic material for use as a catalyst in the photo-Fenton process. The main elements present in the catalyst were silicon, aluminum, oxygen, carbon, phosphorus, and iron, and the specific area was 35.53 m2 g−1. X-ray photoelectron spectroscopy and scanning electron microscopy analyses showed that there was no apparent alteration of the catalyst surface after the photo-Fenton process. Photo-Fenton experiments performed under UV irradiation revealed complete degradation of trimethoprim (TMP) and sulfamethoxazole (SMZ) in purified water after 180 min, with the catalytic activity maintained for at least 4 cycles. A comparison was made of the degradation of pollutants in sewage treatment plant effluents under artificial UV and solar irradiation. Under solar irradiation, at pH 3.5, total degradation of TMP and SMZ was achieved, together with TOC removal of up to 21%, showing SLC-600 as a potential low-cost catalyst to be used in photo-Fenton process.
Poly(methyl methacrylate)-silica-calcium phosphate coatings for the protection of Ti6Al4V alloy
(2023-06-01) Uvida, Mayara Carla ; Pulcinelli, Sandra Helena ; Santilli, Celso Valentim ; Hammer, Peter ; Universidade Estadual Paulista (UNESP)
Poly(methyl methacrylate) (PMMA)-silica coatings modified with calcium phosphates (CaPs) in the form of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) have been developed to improve the corrosion resistance and bioactivity of Ti6Al4V titanium alloys, applied in medical and dental implants. PMMA-silica hybrids containing 1000 ppm HA or β-TCP were prepared by combining the sol-gel reactions of tetraethylorthosilicate (TEOS) with the radical polymerization of methyl methacrylate (MMA) and 3-methacryloxypropyl trimethoxysilane (MPTS), used as molecular coupling agent. Bi-layer coatings about 15 μm thick, deposited by immersion on Ti6Al4V, are homogeneous, defect-free, and exhibit strong adhesion to the substrate (>14 MPa). The addition of HA and β-TCP led to a slight increase in thermal stability, without affecting the structural integrity of the highly crosslinked PMMA-silica matrix. The greater hydrophilicity and surface roughness of coatings containing HA and β-TCP are associated with the size and chemical composition of CaPs, necessary for effective osteointegration. The modified coatings showed high anti-corrosion efficiency with low-frequency impedance modulus values of up to 73 GΩ cm2, remaining stable after 150 days of exposure to simulated body fluid (SBF) solution. Graphical Abstract: [Figure not available: see fulltext.]
Polymeric micelles-mediated photodynamic therapy
(2023-01-01) de Santana, Willian Max O.S. ; Pochapski, Daniel José ; Pulcinelli, Sandra H. ; Fontana, Carla Raquel ; Santilli, Celso V. ; Universidade Estadual Paulista (UNESP)
Polymeric micelles (PM) have been demonstrating high potential as multifunctional therapeutic nanoplatforms for anticancer photodynamic therapy (PDT). PM increase photosensitizer (PS) accumulation in tumor tissues, thus improving its antitumor effect. The development of PM responsive to endogenous (e.g., pH, reducing agents, and hypoxia) or exogenous (e.g., light) stimuli makes these polymeric structures even more versatile, since the delivery of PS to the target tissue occurs with good spatio-temporal control. This chapter covers the application of PM in PDT, focusing on targeting and stimulus-responsiveness release strategies. Our discussion will be based on the physical-chemical properties of the PM and the interaction of these carriers with biological systems.
Microwave-assisted hydrothermal synthesis of Sn3O4 and SnO for electrocatalytic reduction of CO2 to high-added-value compounds
(2023-02-01) Romeiro, Fernanda da Costa ; Martins, Alysson Stefan ; Perini, João Angelo Lima ; Silva, Beatriz Costa e ; Zanoni, Maria Valnice Boldrin ; Orlandi, Marcelo Ornaghi ; Universidade Estadual Paulista (UNESP)
Sn-based electrocatalysts have recently been applied for CO2 reduction to generate fuels. Here, tin oxide crossed architectures (SnO) and petal-like Sn3O4 semiconductors were synthesized using the microwave-assisted hydrothermal method. The synthesized materials were applied in electrochemical reduction of CO2 and promoted the formation of methanol, ethanol and acetone. The best condition (greatest amount of products) was obtained with − 0.5 V vs Ag/AgCl for both electrocatalysts. For the first time, acetone formation was observed using both SnO and Sn3O4 materials. The SnO electrocatalyst exhibited the best electrochemical activity for CO2 reduction, ascribed to higher charge transfer corroborated by the higher current densities and lower resistance in the Nyquist diagram. Differences in methanol concentration obtained by the samples were ascribed to the different morphology and charge transfer over the films. The results showed that Sn-based electrocatalysts can be applied to generate important products, such as methanol and ethanol, aside from promoting acetone formation. Graphical Abstract: [Figure not available: see fulltext.].
Effects of Metal–Support Interaction in the Electrocatalysis of the Hydrogen Evolution Reaction of the Metal-Decorated Titanium Dioxide Supported Carbon
(2023-01-01) Ometto, Felipe Berto ; Paganin, Valdecir Antonio ; Hammer, Peter ; Ticianelli, Edson Antonio ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP)
It has been found that the electrocatalytic properties of metallic nanoparticles supported on transition metal oxides are affected by the existing strong metal–support interaction (SMSI). Herein, the effects of SMSI on the electrocatalysis of the hydrogen evolution reaction (HER) were investigated in acid electrolyte by using Pt and Ag nanoparticles supported on carbon and titanium oxide (TiO2). High-resolution transmission electron microscopy (HR–TEM) images showed that Pt and Ag nanoparticles present a spherical shape at the TiO2 support and an average size distribution of around 4.5 nm. The X-ray photoelectron spectroscopy (XPS) results for Pt/TiO2/C and Ag/TiO2/C evidenced higher amounts of surface oxides in the metallic particles, when compared to the materials supported on carbon. Consistently, electrode polarization and electrochemical impedance results revealed that both metal–TiO2 and metal–C-supported catalysts were more active in catalyzing the HER than the corresponding carbon-supported materials, with Pt presenting better results. These differences in the HER activities were related to the electronic effects of the TiO2/C substrate on the Pt and Ag metals, introduced by strong metal-support (SMSI) in the metal–TiO2/C catalysts.
Surface qualification of AISI 316L bioprocessing tanks applying on-sitelectrochemical measurements
(2022-01-01) Guilherme, Luís Henrique ; Fugivara, Cecílio Sadao ; Benedetti, Assis Vicente ; ACW Engenharia ; Universidade Estadual Paulista (UNESP)
The passivation level of AISI 316L bioprocessing tanks of roughness average of 0.8 μm mechanically polished was assessed. The on-site inspections were performed after tanks manufacturing and in distinct surface conditions: (i) after 12 months of industrial operation, (ii) with biofilm adhesion, (iii) after chemical passivation treatment. The PassivityScan inspection instrument was used in on-site measurements of passivation level applying the open circuit potential and cyclic potentiodynamic polarization techniques. The results showed that the tank inner surface in as-built condition obtained a relative low passivation level (Eprot –Ecorr < 150 mV(Ag|AgCl|KCl 3 mol/L) and high corrosion kinetic. The passivation level and durability of the surface were reduced after 12 months of operation. A worst-case scenario was noted with biofilm adhesion given that the surface was not able to repassivate. It worth to emphasize that the passivation treatment increased the passivation level to 520 mV(Ag|AgCl|KCl 3 mol/L) and reduced the passivation current density from 20 to 0.7 μA cm–2. It was concluded that a passivated AISI 316L tank reach a better operational reliability, and also the chemical passivation treatment should be done every 12 months in order to restorage the passive film resistance.
Effect of Organomontmorillonite-Cloisite® 20A Incorporation on the Structural and Drug Release Properties of Ureasil–PEO Hybrid
(2023-01-01) Jesus, Celso R. N. ; Molina, Eduardo F. ; de Oliveira, Ricardo ; Pulcinelli, Sandra H. ; Santilli, Celso V. ; Universidade Estadual Paulista (UNESP) ; Universidade de Franca
This paper presents the influence of the presence of a modified organoclay, Cloisite® 20A (MMTA) on the structural and drug release properties of ureasil organic–inorganic hybrid. Sol–gel process was used to prepare the hybrid nanocomposites containing sodium diclofenac (DCF) at 5% wt. The effect of the amount of MMTA incorporated into the ureasil hybrid matrix was evaluated and characterized in depth by different techniques such as X-ray diffraction (XRD), small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC), and swelling properties. The influence of MMTA on ureasil nanocomposites release profile was evaluated by in situ UV–vis. The diffraction patterns of the UPEO–MMTA nanocomposites showed a synergistic contribution effect that led to an intensity increase and narrowed the diffraction peaks, evidencing a crystallite PEO growth as a function of the modified nanoclay content. The interactions between polyether chains and the hydrogenated tallow of MMTA led to an easy intercalation process, as observed in UPEO–MMTA nanocomposites containing low (1% wt) or high (20% wt) nanoclay content. The waterway (channels) created in UPEO–MMTA nanocomposites contributed to a free volume increase in the swollen network compared to UPEO without MMTA. The hypothesis of the channels created after intercalation of the PEO phase in the interlayer of MMTA containing organoammonium ions corroborates with the XRD results, swelling studies by SAXS, and release assays. Furthermore, when these clay particles were dispersed in the polymeric matrix by an intercalation process, water uptake improvement was observed, with an increased amount of DCF release. The design of ureasil-MMTA nanocomposites containing modified nanoclay endows them with tunable properties; for example, swelling degree followed by amount of controlled drug release, opening the way for more versatile biomedical applications.
Modifications in the Surface of Titanium Substrate and the Incorporation of an Essential Oil for Biomaterial Application
(2022-01-01) Ferreira, Carolina Cruz ; de Sousa, Lucíola Lucena ; Barboza, Carla Sérgio ; Marques, Rodrigo Fernando Costa ; Mariano, Neide Aparecida ; Universidade Estadual de Campinas (UNICAMP) ; Universidade Federal de Alfenas (UNIFAL) ; Universidade Estadual Paulista (UNESP)
Metallic prostheses are the most used for the partial or total recovery of damaged organs and tissues, with titanium being the most applied material. Aiming to enhance the device to be implanted, the application of polymeric and ceramic coatings has been studied. The use of polycaprolactone (PCL) has shown promising characteristics, given its biodegradability, and the addition of hydroxyapatite (HA) has favored osseointegration. Nevertheless, complications related to infectious processes are recurrent to surgical procedures. In this context, the present study proposes the manufacture of a functional hybrid material for prosthetic application. As a strategy to minimize postsurgical bacterial contamination, this work proposes the incorporation of Melaleuca alternifolia essential oil (TTO) as a natural bactericide, in polycaprolactone and hydroxyapatite coatings in a titanium substrate. The samples were characterized to demonstrate that the coatings were performed on the whole surface of the titanium and that the incorporation of the essential oil did not alter the morphology of the polymeric film. The surface morphological evaluation performed after the corrosion assays in simulated body fluid indicated there was PCL degradation, being more intense for the samples containing HA, deriving from the alteration in the polymeric coating hydrophilicity combined with the bioceramic and the increase in surface porosity. Simultaneously to the process of polymeric layer degradation, it is suggested that there will be a release of the TTO incorporated in PCL and the formation of overlapping apatitic layers. Therefore, the results demonstrated that the proposed coatings may contribute to biocompatibility and the osseointegrative process, indicating the potentiality for application in orthopedic medical devices.
Self-Healing Organic-Inorganic Coatings
(2022-11-01) Hammer, Peter ; Uvida, Mayara Carla ; Trentin, Andressa ; Universidade Estadual Paulista (UNESP) ; Materials Performance
Appraisal of Ni Species Supported on Porous MgO during Ethanol Steam Reforming by XAS
(2022-11-08) Possato, Luiz G. ; Pulcinelli, Sandra H. ; Martins, Leandro ; Briois, Valerie ; Santilli, Celso V. ; Universidade Estadual Paulista (UNESP) ; L'Orme des Merisiers BP48
Operando time-resolved X-ray absorption spectroscopy (XAS) was used to determine nickel species supported on porous MgO during the ethanol steam reforming reaction. The Principal Component Analysis (PCA) of the nickel K-edge XAS spectra revealed Ni(OH)2, NiMgO, and metallic Ni during the activation and reaction of the catalysts. The Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method for the time-resolved XAS spectra data permitted to calculate the concentration of species during the activation and reaction steps and to determine the formation of NiMgO and nickel reduction degree. The samples prepared with surfactants, Ni10MgO-F127 and Ni10MgO-P123, showed less nickel reduction (less than 30 %) but were more active and stable than the reference Ni10MgO catalyst, which reduced 52 %. It happened due to the smaller particle size and a larger specific area of the porous supports. The samples synthesized without Pluronic deactivated, and ethanol dehydrogenation became predominant instead of the ethanol steam reforming.
Assessment of Charge Transport through Barrier Membranes before Application on Materials Surfaces
(2022-01-01) Nardeli, Jéssica Verger ; Fugivara, Cecílio Sadao ; Benedetti, Assis Vicente ; Universidade Estadual Paulista (UNESP)
This work aims at investigating the charge transfer resistance (RCT) of the two membranes derived from vegetable oils which are intended to protect materials against corrosion. The membranes were characterized by thickness measurement (328±1 μm and 491± 1 μm), atomic force microscopy (AFM) to estimate of roughness (<0.5 μm), Raman spectroscopy while the RCT values were evaluated by electrochemical impedance spectroscopy (EIS) in 0.1 mol/L KCl solution. EIS was used to measure the impedance at low frequency (Z0.01Hz ≅ 109 Ω cm2), RCT ≅ 109 Ω cm2 and exchange current density (i0 ≅ 10-11 Ω cm2), employing simple instrumentation. The thickness of the membrane must be considered for coherent interpretation of the impedance results. The study of electrolytes permeation in membranes is important to previously estimate the lifetime offered to a substrate over the time of immersion even before being applied to the metallic surface. The impedance measurements demonstrated that the most resistant membrane to permeation presented a RCT around 2 GΩ cm2. This EIS measurements approach enables the optimization of membrane fabrication by conveniently identifying the best formulation.
Effective Fenton-like degradation of the tebuthiuron herbicide by ferrocene functionalized g-C3N4
(2023-02-01) Sánchez-Montes, Isaac ; Carneiro Doerenkamp, Jussara ; Núñez-de la Rosa, Yeison ; Hammer, Peter ; Rocha-Filho, Romeu C. ; Aquino, José M. ; Universidade Federal de São Carlos (UFSCar) ; Universidade Estadual Paulista (UNESP)
At the present time, proper treatments of water and wastewater stand as one of the main concerns of our society due to otherwise potential health and environmental problems. Thus, this work aimed to synthesize, characterize, and use graphitic carbon nitride (g-C3N4) functionalized with ferrocenecarboxaldehyde (Fc) to assess its performance in the oxidation of the tebuthiuron (TBT) herbicide by in situ chemical activation reaction using hydrogen peroxide (H2O2 – HP) or persulfate (S2O82− – PS) as oxidant under white light irradiation. For that, the TBT concentration as well as oxidant consumption and main products in the form of carboxylic acids and inorganic ions were monitored during the oxidation experiments. Morphological, structural, and electrochemical assays confirmed that Fc functionalized g-C3N4 (g-C3N4/Fc) was indeed obtained, showing the expected activation of the Fe(III)/Fe(II) redox pair. Using g-C3N4/Fc to activate HP and PS, a complete oxidation of TBT was achieved only when using HP under acidic conditions (pH 3, [g-C3N4/Fc] = 0.250 g L−1, [HP] = 1 mmol L−1), with a total HP consumption of 50% after 120 min of treatment. However, the degree of mineralization of the organic load was low; acetic and formic acid were the main carboxylic acids produced as well as nitrate ions, but far below the theoretical value of complete mineralization. The main oxidant species leading to TBT oxidation were the hydroxyl radical and, to lesser extent, the sulfate radical. The in situ activation process mediated by g-C3N4/Fc was also dependent on produced electrons to regenerate Fe(II) ions, especially when using HP.
Analysis of the biocompatibility of a biocelulose and a poly L-lactic acid membrane
(2021-01-01) Neto, José Doval ; Marques, Rodrigo Fernando Costa ; Motta, Adriana Cristina ; de Rezende Duek, Eliana Aparecida ; de Oliveira, Guilherme José Pimentel Lopes ; Marcantonio, Cláudio ; Araraquara University Center (UNIARA) ; Universidade Estadual Paulista (UNESP) ; Universidade de São Paulo (USP) ; Universidade Federal de Uberlândia (UFU)
The use of selective barriers as resorbable membranes has become a routine clinical procedure for guided bone regeneration. Therefore, the production of membranes with a low inflammatory potential during their resorption process has become the goal of a considerable number of researches. Aim: The purpose of the present study was to evaluate the biocompatibility of poly (L-lactic acid) (PLLA) and biocelulose membranes (BC) inserted in the subcutaneous tissue on the dorsum of rats. Methods: Fifteen animals underwent surgical procedures for the insertion of 4 types of membranes: COL (Collagen membrane) – Control Group; BC (Biocellulose membrane); BCAg (Biocellulose membrane impregnated with Silver); PLLA (Poly (L-lactic acid) membrane). All membrane types were inserted into each animal. Animals were euthanized after 3, 7, and 15 days of the surgical procedure. Descriptive histological analyses were carried out to investigate host tissue reaction to membrane presence by assessing the anti-inflammatory process composition associated with the membrane resorption and the presence of foreign-body reaction or encapsulation. Results: The BC membranes showed a higher degree of inflammation and poor pattern of integration with the surrounding tissues than the PLLA and COL membranes. Conclusion: The PLLA and COL membranes present better biocompatibility than the BC membranes.
Quantum Rate Theory for Graphene
(2022-09-15) Bueno, Paulo Roberto ; Miranda Mercado, David Alejandro ; Universidade Estadual Paulista (UNESP) ; CIMBIOS-CMN Group
The quantum rate theory predicts the electron transfer rate between quantum states governed by the ratio between the quantum conductance and capacitance (Phys. Chem. Chem. Phys. 2020, 22, 26109-26112). This rate is important not only for describing the quantumness of the electron transfer of electrochemical reactions but also for understanding electron transport in molecular electronics (Phys. Chem. Chem. Phys. 2020, 22 (19), 10828-10832). Additionally, this quantum rate principle is applicable for describing conductive and capacitive V-shapes of graphene (Carbon 2021, 184 821-827). In the present work, we demonstrate the relationship between the quantum rate theory for a single-layer graphene and the relativistic quantum mechanical theory of electrons according to the Dirac equation. As the merger of quantum mechanics and relativity theory, quantum rate theory is the key to analyzing quantum electrodynamics in two-dimensional structures (e.g., honeycomb-like carbon such as graphene) using an inexpensive benchtop electrochemical setup. In this study, the quantum rate model for graphene is introduced along with its applicability to the diffusionless electrochemical transport of electrons, as exemplified for molecular films comprising redox switches. This didactic approach demonstrates that the best means of conducting electron transport in graphene is the AC mode of electric current modulation, in which electric displacement current is imperative. A maximum quantum rate of electron transport occurs at the Dirac point, where net carrier concentrations are at their minimum, in contrast to the traditional DC mode of modulating conductance. This analysis opens an avenue of possibilities for fabricating quantum devices with electronic semiconducting accuracy, for example, biological sensors in complex environments.
Self-healing nanocoatings
(2022-01-01) Trentin, Andressa ; Uvida, Mayara Carla ; de Araújo Almeida, Adriana ; de Souza, Thiago Augusto Carneiro ; Hammer, Peter ; Universidade Estadual Paulista (UNESP)
The current demand of the automotive industry for durable high-performance paints with self-healing ability and environmental compatibility has prompted the research for the next-generation coatings. To accomplish extended durability, the development of smart coatings has been pursued, aiming to provide active protection after a corrosive or mechanical failure. Different approaches are used for developing smart/self-healing coatings, such as the addition of micro/nanocapsules containing organic or inorganic healing agents, vascular or shape memory polymers, polymers with reversible covalent bonds, and self-healing agents based on organic and inorganic compounds. The latter strategy, in particular, presents an excellent cost-benefit and low complexity, making this approach very promising for applications in the automotive industry. In this chapter, we give an overview of the state of the art of high-performance coatings, with particular emphasis on the smart inhibition mechanisms in different coating systems, providing the reader with an update on emerging self-healing technologies.
Recent Advances in Nanostructured Polymer Composites for Biomedical Applications
(2019-01-01) Silva, Andre D.R. ; Stocco, Thiago D. ; Granato, Alessandro E.C. ; Harb, Samarah V. ; Afewerki, Samson ; Bassous, Nicole J. ; Hammer, Peter ; Webster, Thomas J. ; Marciano, Fernanda Roberta ; Lobo, Anderson O. ; Air Force Academy ; Universidade Estadual de Campinas (UNICAMP) ; Santo Amaro University ; Universidade de São Paulo (USP) ; Universidade Estadual Paulista (UNESP) ; Brigham & Women’s Hospital ; Massachusetts Institute of Technology ; Northeastern University ; UFPI-Federal University of Piaui
The use of nanostructured polymer composites has surged to the forefront as a promising class of hybrid materials to design biomimetic structures for biomedical applications. The association of two or more classes of nanomaterials not only improves the intrinsic properties of composites, but also presents structural and chemical similarity to organic and inorganic parts of our body. A plethora of chemistries, compositions, and nanofillers have been extensively used for biomedical applications, especially for tissue engineering purposes. The great challenge of nanostructured polymer composites is to mimic (chemically and structurally) the extracellular matrices from different parts of the human body to promote tissue regeneration. Herein, we discuss recent efforts and key research challenges regarding natural, synthetic, and hybrid polymers both with and without organic and inorganic fillers employed for biomedical applications. An overview of three-dimensional bioprinting using nanocomposite hydrogels is also presented. We hope that the final comments and future directions presented here will pave the way for designing and conducting innovative research within the field and by that extend the thematic and fundamental understanding.
Advanced organic nanocomposite coatings for effective corrosion protection
(2020-01-01) Harb, Samarah Vargas ; Trentin, Andressa ; Uvida, Mayara Carla ; Hammer, Peter ; Universidade Estadual Paulista (UNESP)
Recent advances of nanotechnology allowed a huge step forward in the field of protective coatings based on polymeric composites. The incorporation of nanofillers into organic matrices has proven to enhance essential properties for anticorrosive application, including adhesion to metallic substrates, cross-linked nanostructure that blocks the entrance of corrosive species, mechanical strength to withstand deformation in aggressive environments, and thermal stability for high-temperature applications. Acrylates, epoxy, and polyurethanes coatings modified with inorganic oxides, carbon nanostructures, and clays have provided excellent corrosion protection for metallic surfaces with impedance modulus up to 100 GΩ cm2 and durability of months in corrosive environments. Although less exploited, other polymeric nanocomposites containing fluoropolymers, conducting polymers, polyesters, etc., are promising materials for efficient corrosion protection; therefore, further advances are expected in near future. This chapter gives an overview on the state of the art of nanocomposite high-efficiency protective coatings, giving special emphasis to the potential of organic–inorganic hybrid materials.
Ultrasonic application and spray drying during amorphous calcium phosphate synthesis
(2019-12-30) Chanfrau, Jorge E. Rodriguez ; Pantoja, Yaymarilis Veranes ; Guastaldi, Antonio Carlos ; Universidade Estadual Paulista (UNESP) ; University of Havana
Hydroxyapatite, amorphous calcium phosphates, calcium triphosphate and calcium octaphosphate are the main components present in bones and teeth. Calcium phosphates are easily synthesized, playing an important role in regenerative medicine, being able to be used as bone implants. There are different ways of synthesizing phosphates, the most commonly used being wet chemical method. The objective of this work was to study the influence of the use of ultrasound and spray drying on the synthesis of amorphous calcium phosphate. Two synthetic variants were studied. One without ultrasound application and the other with ultrasound application. The samples obtained were characterized by X-ray diffraction, FTIR spectroscopy and scanning electron microscopy. The particle size by electron microscopy and the calcium content by atomic absorption was determined. The results showed that when spray drying is applied, particle sizes of less than 261 nm are obtained in the samples synthesized without ultrasound application, being less than 59 nm in the samples synthesized with ultrasound application. The statistical analysis by ANOVA showed significant differences between the particle sizes of the samples synthesized without ultrasound application and the samples synthesized by applying ultrasound. In both cases the particles were spherical. The results obtained show that the application of ultrasound during the synthesis process decreases the particle size, increasing the surface area, which favors the spray drying process.
Detection of intestinal parasites in human faecal samples using dissolved air flotation
(2022-12-01) Soares, Felipe Augusto ; dos Santos, Bianca Martins ; Rosa, Stefany Laryssa ; Loiola, Saulo Hudson Nery ; Stéfano, Vitória Castilho ; Proença, Letícia Rodrigues ; Suzuki, Celso Tetsuo Nagase ; Sabadini, Edvaldo ; Bresciani, Katia Denise Saraiva ; Falcão, Alexandre Xavier ; Gomes, Jancarlo Ferreira ; Universidade Estadual de Campinas (UNICAMP) ; ImmunoCamp Science and Technology ; Universidade Estadual Paulista (UNESP)
Objective: Ova and parasite (O&P) examination is recommended for the laboratory diagnosis of agents causing parasitic infections; however, this exam requires scientific and technological improvements to enhance its diagnostic validity. Dissolved air flotation (DAF) is an efficient technical principle separating suspended solids in a liquid medium. We aimed to develop and validate a new procedure for intestinal parasite detection with DAF. Methods: In this study, we collected samples from 500 volunteers, screened them by direct examination, and transferred the material to tubes using the Three Faecal Test (TF-Test) for triplicate DAF tests. We evaluated physical–chemical parameters and DAF prototype components through quantifying parasites recovered from floated and non-floated regions of the flotation column. The DAF operation protocol was validated with the gold standard results. Results: The 10% saturated volume proportion and cationic surfactant showed regularity and high parasite recovery (80%). Modifications of the needle device did not influence parasite recovery (p > 0.05). Sensitivity, specificity, accuracy and kappa agreement obtained with the DAF protocol were 91%, 100%, 93% and substantial (k = 0.64), respectively. Conclusion: The DAF principle could be used to process faecal samples in routine laboratory exams, enabling intestinal parasite detection.
Modular 3D-printed fluorometer/photometer for determination of iron(ii), caffeine, and ciprofloxacin in pharmaceutical samples
(2023-04-17) Lamarca, Rafaela Silva ; Silva, João Pedro ; Varoni dos Santos, João Paulo ; Ayala-Durán, Saidy Cristina ; Lima Gomes, Paulo Clairmont Feitosa de ; Universidade Estadual Paulista (UNESP)
The demand for the development of portable and low-cost analytical devices has encouraged studies employing additive manufacturing techniques, such as 3D-printing. This method can be used to produce components such as printed electrodes, photometers, and fluorometers for low-cost systems that provide advantages including low sample volume, reduced chemical waste, and easy coupling with LED-based optics and other instrumental devices. In the present work, a modular 3D-printed fluorometer/photometer was designed and applied for the determination of caffeine (CAF), ciprofloxacin (CIP), and Fe(ii) in pharmaceutical samples. All the plastic parts were printed separately by a 3D printer, using Tritan as the plastic material (black color). The final size of the modular 3D-printed device was 12 × 8 cm. The radiation sources were light-emitting diodes (LEDs), while a light dependent resistor (LDR) was used as a photodetector. The analytical curves obtained for the device were: y = 3.00 × 10−4 [CAF] + 1.00 and R2 = 0.987 for caffeine; y = 6.90 × 10−3 [CIP] − 3.39 × 10−2 and R2 = 0.991 for ciprofloxacin; and y = 1.12 × 10−1 [Fe(ii)] + 1.26 × 10−2 and R2 = 0.998 for iron(ii). The results obtained using the developed device were compared with reference methods, with no statistically significant differences observed. The 3D-printed device was composed of moveable parts, providing flexibility for adaptation and application as a photometer or fluorometer, by only switching the photodetector position. The LED could also be easily switched, permitting application of the device for different purposes. The cost of the device, including the printing and electronic components, was lower than US$10. The use of 3D-printing enables the development of portable instruments for use in remote locations with a lack of research resources.

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