Araraquara - IQAR - Instituto de Química

URI Permanente para esta coleçãohttps://hdl.handle.net/11449/253734

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Contribution of CuO on lamellar BiVO4/Bi2O3-based semiconductor for photoconversion of CO2
(2023-10-01) Corradini, Patricia Gon ; Brito, Juliana Ferreira de ; Blaskievicz, Sirlon F ; Salvati, Byanca S ; Menezes, Beatriz Costa e Silva ; Zanoni, Maria Valnice Boldrin ; Mascaro, Lucia Helena ; Universidade Federal de São Carlos (UFSCar) ; Science and Technology ; Universidade Estadual Paulista (UNESP)
Lamellar BiVO4 is a photocatalyst recognized as an effective visible-light-driven semiconductor that is active in CO2 reduction but faces challenges such as high recombination rate and low mobility of photogenerated charge carriers. Additionaly, CuXO are well-known materials for CO2 photosynthesis, and Bi2O3 improves the generation of organic compounds from CO2 reduction with more than one carbon. In this sense, this paper evaluates the influence of small amounts of copper oxide on lamellar BiVO4-Bi2O3 prepared by a microwave-assisted route on the CO2 photoreduction activity. Lamellar BiVO4-Bi2O3 powder catalysts modified by different percentages of CuO were synthesized using microwave heating at 140 °C and 1200 rpm for 15 min. Electrochemical and photochemical characterizations showed that small amounts of copper, such as 1.0%, enhanced the absorption of visible light, improved charge transfer, mitigated charge recombination, and increased the yield of products (acetone and methanol). Furthermore, the flat band potential of the catalyst modified with 1.0% of copper was located at a more negative potential than the unmodified sample, which favored the photocatalytic reduction of the CO2. As a result, the study achieved a 38-fold improvement in methanol generation (1373.5 µmol L−1 gcat−1) and a 62% increase in acetone formation (12.5 µmol L−1 gcat−1) under UV–Vis light incidence over 2 h of reaction at ambient pressure and temperature, compared to pure BiVO4 (36.3 µmol L−1 gcat−1 of methanol and 7.7 µmol L−1 gcat−1 of acetone).
Electrochemical sensor based on carbon nanotube decorated with manganese oxide nanoparticles for naphthalene determination
(2023-01-01) Alves, Ismael Carlos Braga ; dos Santos, José Ribamar Nascimento ; Marques, Edmar Pereira ; Sousa, Janyeid Karla Castro ; Beluomini, Maísa Azevedo ; Stradiotto, Nelson Ramos ; Marques, Aldaléa Lopes Brandes ; Federal University of Maranhão (UFMA) ; Universidade Estadual Paulista (UNESP)
In this work, an electrochemical sensor was developed for the determination of naphthalene (NaP) in well water samples, based on a glass carbon electrode (GCE) modified as a nanocomposite of manganese oxides (MnOx) and COOH-functionalized multi-walled carbon nanotubes (MWCNT). The synthesis of MnOx nanoparticles was performed by the sol–gel method. The nanocomposite was obtained by mixing MnOx and MWCNT with the aid of ultrasound, followed by stirring for 24 h. Surface modification facilitated the electron transfer process through the MnOx/MWCNT/GCE composite, which was used as an electrochemical sensor. The sensor and its material were characterized by cyclic voltammetry (CV), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Important parameters influencing electrochemical sensor performance (pH, composite ratios) were investigated and optimized. The MnOx/MWCNT/GCE sensor showed a wide linear range of 2.0–16.0 μM, a detection limit of 0.5 μM and a quantification limit of 1.8 μM, in addition to satisfactory repeatability (RSD of 7.8%) and stability (900 s) in the determination of NaP. The determination of NaP in a sample of water from a gas station well using the proposed sensor showed results with recovery between 98.1 and 103.3%. The results obtained suggest that the MnOx/MWCNT/GCE electrode has great potential for application in the detection of NaP in well water. Graphical abstract: [Figure not available: see fulltext.]
The Dimeric Peptide (KKYRYHLKPF)2K Shows Broad-Spectrum Antiviral Activity by Inhibiting Different Steps of Chikungunya and Zika Virus Infection
(2023-05-01) Ayusso, Gabriela Miranda ; Lima, Maria Letícia Duarte ; da Silva Sanches, Paulo Ricardo ; Santos, Igor Andrade ; Martins, Daniel Oliveira Silva ; da Conceição, Pâmela Jóyce Previdelli ; Carvalho, Tamara ; da Costa, Vivaldo Gomes ; Bittar, Cíntia ; Merits, Andres ; Santos-Filho, Norival Alves ; Cilli, Eduardo Maffud ; Jardim, Ana Carolina Gomes ; de Freitas Calmon, Marilia ; Rahal, Paula ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de Uberlândia (UFU) ; The Rockefeller University ; University of Tartu
Chikungunya virus (CHIKV) and Zika virus (ZIKV) are important disease-causing agents worldwide. Currently, there are no antiviral drugs or vaccines approved to treat these viruses. However, peptides have shown great potential for new drug development. A recent study described (p-BthTX-I)2K [(KKYRYHLKPF)2K], a peptide derived from the Bothropstoxin-I toxin in the venom of the Bothrops jararacussu snake, showed antiviral activity against SARS-CoV-2. In this study, we assessed the activity of this peptide against CHIKV and ZIKV and its antiviral action in the different stages of the viral replication cycle in vitro. We observed that (p-BthTX-I)2K impaired CHIKV infection by interfering with the early steps of the viral replication cycle, reducing CHIKV entry into BHK-21 cells specifically by reducing both the attachment and internalization steps. (p-BthTX-I)2K also inhibited the ZIKV replicative cycle in Vero cells. The peptide protected the cells against ZIKV infection and decreased the levels of the viral RNA and the NS3 protein of this virus at viral post-entry steps. In conclusion, this study highlights the potential of the (p-BthTX-I)2K peptide to be a novel broad-spectrum antiviral candidate that targets different steps of the replication cycle of both CHIKV and ZIKV.
Interaction of Aspergillus niger in Double-Coated Urea Granules Reduces Greenhouse Gas Emissions from N Fertilization
(2023-01-01) Majaron, Vinícius F. ; da Silva, Marisa G. ; Pfeifer, Marcela ; Bortoletto-Santos, Ricardo ; Velloso, Camila C. V. ; Klaic, Rodrigo ; Polito, Wagner L. ; Ribeiro, Sidney J. L. ; Bernardi, Alberto C. C. ; Farinas, Cristiane S. ; Ribeiro, Caue ; Universidade Federal de São Carlos (UFSCar) ; Universidade de Ribeirão Preto (UNAERP) ; Universidade Estadual Paulista (UNESP) ; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) ; Universidade de São Paulo (USP)
Urea is the main nitrogen source applied in agriculture and directly impacts agricultural productivity. However, it presents significant losses that reduce plants’ nitrogen use efficiency (NUE) and promote greenhouse gas emissions, such as N2O. The coating technology allows for an increase in the NUE, making the nutrient available gradually and uniformly, and combining with microorganisms’ action. This work developed and evaluated a double-coating system based on castor oil–polyurethane and maize starch activated by Aspergillus niger for urea granules. We tested the coated urea granules in Palisade grass (Brachiaria brizantha) and measured losses of N2O and NH3. The results showed that the combination between controlled release and Aspergillus niger action reduced the N2O and NH3 emissions, suggesting a local buffering pH effect. The urea loss reduction significantly impacted plant development, increasing N use efficiency, dry mass production, and N uptake. The results support the suitability of a coating system combining controlled release and microorganisms, aiming to better synchronize the nutrient with the plant and reduce environmental impacts. Graphical Abstract: [Figure not available: see fulltext.]
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.
Designing Highly Photoactive Hybrid Aerogels for In-Flow Photocatalytic Contaminant Removal Using Silica-Coated Bacterial Nanocellulose Supports
(2023-05-17) Almeida da Silva, Thaís Caroline ; Marchiori, Leonardo ; Oliveira Mattos, Bianca ; Ullah, Sajjad ; Barud, Hernane da Silva ; Romano Domeneguetti, Rafael ; Rojas-Mantilla, Hernán Dario ; Boldrin Zanoni, Maria Valnice ; Rodrigues-Filho, Ubirajara Pereira ; Ferreira-Neto, Elias Paiva ; Ribeiro, Sidney José Lima ; Universidade Estadual Paulista (UNESP) ; Universidade de São Paulo (USP) ; University of Peshawar─UOP ; University of Araraquara─UNIARA ; Universidade Federal de Santa Catarina (UFSC)
This study explores the use of silica-coated bacterial nanocellulose (BC) scaffolds with bulk macroscopic yet nanometric internal pores/structures as functional supports for high surface area titania aerogel photocatalysts to design flexible, self-standing, porous, and recyclable BC@SiO2-TiO2 hybrid organic-inorganic aerogel membranes for effective in-flow photo-assisted removal of organic pollutants. The hybrid aerogels were prepared by sequential sol-gel deposition of the SiO2 layer over BC, followed by coating of the resulting BC@SiO2 membranes with a porous titania aerogel overlayer of high surface area using epoxide-driven gelation, hydrothermal crystallization, and subsequent supercritical drying. The silica interlayer between the nanocellulose biopolymer scaffold and the titania photocatalyst was found to greatly influence the structure and composition, particularly the TiO2 loading, of the prepared hybrid aerogel membranes, allowing the development of photochemically stable aerogel materials with increased surface area/pore volume and higher photocatalytic activity. The optimized BC@SiO2-TiO2 hybrid aerogel showed up to 12 times faster in-flow photocatalytic removal of methylene blue dye from aqueous solution in comparison with bare BC/TiO2 aerogels and outperformed most of the supported-titania materials reported earlier. Moreover, the developed hybrid aerogels were successfully employed to remove sertraline drug, a model emergent contaminant, from aqueous solution, thus further demonstrating their potential for water purification.
Hydrotalcite loading boosts the potentially toxic element's retention in hydrogel nanocomposites for environmental treatment
(2023-08-01) Pfeifer, Marcela ; Bortoletto-Santos, Ricardo ; Andrade, Flávio A.C. ; Ribeiro, Sidney J.L. ; Aouada, Fauze A. ; Ribeiro, Caue ; Universidade Federal de São Carlos (UFSCar) ; Programa de pós-graduação em Tecnologia Ambiental ; Universidade Estadual Paulista (UNESP) ; Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
The improper disposal of potentially dangerous metal-containing wastes is detrimental to the environment and human health, requiring the development of easy methods for removing these cations, particularly in water bodies. The influence of different surface-charged lamellar materials on the sorption and desorption of Cr6+, Cu2+, and Mn2+ in aqueous solutions was investigated by modifying polyacrylamide/methylcellulose (PAc-MC) hydrogels with bentonite or hydrotalcite. In disk or powder form, the adsorption and desorption capabilities were examined. Regardless of their shape, the bentonite-hydrogel and unmodified hydrogel revealed lower contaminant retention capacities on polymeric structures. In contrast, the hydrotalcite-hydrogel demonstrated a stronger affinity for holding ions in the nanocomposite polymeric structure. The nanocomposite produced by calcining hydrotalcite at 550 °C displayed the best retention properties. Shapes of disks or powders did not affect sorption capacity, but disks were considerably more practical for recovering processed materials. These findings contribute to comprehending the retention capacity of modified hydrogels (or modified nanocomposites).
Simultaneous disinfection of urban wastewater and antibiotics degradation mediated by CuMgFe-B(OH)4 layered double hydroxide with different oxidizing agents
(2023-06-15) de Melo Costa-Serge, Nayara ; Li, Chan ; Fernandes Pupo Nogueira, Raquel ; Chiron, Serge ; Universidade Estadual Paulista (UNESP) ; IRD
The activation of peroxymonosulfate (PMS), peroxydisulfate (PDS) and hydrogen peroxide (H2O2) by CuMgFe-B(OH)4 layered double hydroxide (LDH) was investigated for the degradation of selected antibiotics (i.e., sulfamethoxazole, ciprofloxacin, cephalexin and amoxicillin) and for bacterial disinfection (Escherichia coli and Enterococcus faecalis) in secondary treated urban wastewater in dark condition. The catalyst synthesized behaved differently according to the oxidants used. H2O2 activated system was efficient for disinfection but not for antibiotics degradation due to the formation of complexes between LDH cations and H2O2. PDS activated system relied on a non-radical pathway mostly involving singlet oxygen and Cu(III) with antibiotics removal but with a disinfection capacity limited to E. coli. The comparison of the investigated systems for the removal of SMX in the secondary treated urban wastewater (STWW) showed 18% and 48% of SMX removal after 120 min of reaction with H2O2 and PDS, respectively. On the other hand, with PMS, SMX was below detection limit after 20 min of reaction, demonstrating the superior performance of LDH/PMS for the treatment of STWW. Furthermore, PMS activated with LDH provided > 90% removal of all antibiotics after 120 min and complete inactivation of the pathogens using 0.5 g L-1 of LDH and 4 mM of PMS.
Photobioelectrocatalysis of Intact Photosynthetic Bacteria Exposed to Dinitrophenol
(2023-01-01) de Moura Torquato, Lilian Danielle ; Matteucci, Rosa Maria ; Stufano, Paolo ; Vona, Danilo ; Farinola, Gianluca M. ; Trotta, Massimo ; Boldrin Zanoni, Maria Valnice ; Grattieri, Matteo ; Università degli Studi di Bari “Aldo Moro” ; Universidade Estadual Paulista (UNESP) ; Institute of Nanotechnology Consiglio Nazionale delle Ricerche ; IPCF-CNR Istituto per i Processi Chimico Fisici Consiglio Nazionale delle Ricerche
The outstanding metabolic versatility of purple non-sulphur bacteria makes these organisms an ideal candidate for developing photobioelectrochemical systems applicable in contaminated environments. Here, the effects of 2,4 dinitrophenol, a common contaminant, on purple bacteria photobioelectrocatalysis were investigated. The aromatic contaminant clearly affects current generation, with an enhanced photocurrent obtained at low dinitrophenol concentrations (0.5–1 μM), while higher values (up to 100 μM) resulted in a gradual decrease of photocurrent. The obtained electrochemical evidence, coupled to spectroscopic studies, allowed verifying the viability of the bacteria cells after exposure to dinitrophenol, and that no alteration of the photosynthetic apparatus was obtained. The results indicate that high dinitrophenol concentrations divert electrons from the extracellular electron pathway to an alternative electron sink. The present results open the door to the possible use of intact bacteria-based photoelectrodes to develop technologies for sustainable biosensors with simultaneous environmental remediation.
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.]
Green host urethanesil based on castor oil doped with Eu3+ complex
(2023-04-01) de Freitas, Beatriz Damasio ; Onishi, Bruno Seiki Domingos ; Caixeta, Fabio Jose ; Bortoletto-Santos, Ricardo ; Garcia, Francis Dayan Rivas ; Messaddeq, Younes ; Ribeiro, Sidney Jose Lima ; Universidade Estadual Paulista (UNESP) ; University of Ribeirão Preto (UNAERP) ; Universidade de São Paulo (USP) ; Université Laval
Polymers based on vegetable oils can be suitable candidates for the replacement of fossil polymers, for instance, polyurethanes (PU) based on castor oil. However, the synthesis PU materials are normally carried out using organic solvents, metals, and high temperatures. To overcome these problems, the sol-gel route is an alternative approach based on mild conditions to produce organic-inorganic hybrid urethanesil (Ut) environmentally friendly. Therefore, in this study, we proposed an organic-inorganic hybrid (OIH) synthesis based on castor oil (CO)-derived Ut, as well as the incorporation and interaction of europium β-diketone [Eu(tta)3(H2O)2] in organic-inorganic hybrid matrix. The Ut self-supporting hybrid was synthesized from the reaction of 3-(triethoxysilyl)propyl isocyanate (ICPTES) and CO in a 3:1 M ratio. The films were obtained using the sol-gel process, following the casting method. The CO-based OIH-Ut films showed high transmittance in the visible and infrared spectrum (90%), and urethanesil showed photoluminescence (PL) with emission at 416.0 nm when excited at 319.0 nm. The results also revealed an increase in the intrinsic quantum yield of PL (QLEu) for [Eu(tta)3(H2O)2]. It has been verified a QLEu value of 27% for the isolated complex, whereas when it is incorporated into OIH-Ut a value of 49% was observed.
A Novel Synthesis of a Magnetic Porous Imprinted Polymer by Polyol Method Coupled with Electrochemical Biomimetic Sensor for the Detection of Folate in Food Samples
(2022-11-01) Khan, Sabir ; Wong, Ademar ; Rychlik, Michael ; Sotomayor, María del Pilar Taboada ; Federal Rural University of the Semi-Arid ; Universidade Estadual Paulista (UNESP) ; Technical University of Munich ; Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM)
The present study reports the development and application of a novel, sensitive, and selective voltammetric sensor for the quantitation of folate or vitamin B9 in foodstuffs. The sensor was made from magnetic molecularly imprinted polymers (MMIPs), which were synthesized by the core–shell method using magnetite nanoparticles obtained by the polyol method. The MMIP-based sensor was used for the selective and specific detection of folate in different food samples. The MMIP material was constructed using magnetic water-dispersible nanomaterial, which was prepared by immersing iron (III) acetylacetonate in tri-ethylene-glycol (TEG) solvent. The magnetic water-dispersible nanomaterial was then subjected to polymerization using allyl alcohol as a functional monomer, ethylene-glycol-dimethacrylate (EGDMA) as a cross-linking agent, and 2,2-Azobisisobutyronitrile (AIBN) as a radical initiator. The proposed magnetic materials were characterized by Brunauer–Emmett–Teller (BET), field emission gun scanning electron microscopy (FEG-SEM), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) analysis. The quantification of folate was performed by square wave voltammetry under optimized conditions using 15 mg of MMIPs and 85 mg of carbon paste. The modified electrode presented a linear dynamic range (LDR) of 2.0–12 µmol L−1 and a limit of detection (LOD) of 1.0 × 10−7 mol L−1 in 0.1 mol L−1 acetate buffer solution (pH 4.0). The proposed sensor was successfully applied for folate detection in different food samples, where recovery percentages ranging from 93 to 103% were obtained. Finally, the results obtained from the analysis of selectivity showed that the modified biomimetic sensor is highly efficient for folate determination in real food samples. Adsorption tests were used to evaluate and compare the efficiency of the MMIPs and magnetic non-molecularly imprinted polymer (MNIPs)—used as control material, through the application of HPLC as a standard method.
UV-protective compound-containing smart textiles: A brief overview
(2023-01-01) Barcha Lupino, João Henrique ; Saito, Gustavo Pereira ; Cebim, Marco Aurélio ; Davolos, Marian Rosaly ; Universidade Estadual Paulista (UNESP)
Excessive exposure to solar ultraviolet (UV) radiation causes human health damages, such as sunburns and skin cancer. Thus, the use of sun-protective clothing is a simple, easy, and practical method for UV protection of the human organism. In this perspective, incorporation, coating, and anchorage of UV-protective compounds in textile fibers have been employed to enhance the UV-blocking ability and/or promote functional finishings to smart fabrics. This review describes recent research efforts on the development of UV-protective compound-containing smart fabrics highlighting the UV-blocking properties and multifunctional activities. Different compound class examples and discussions are presented in order to contribute to new insights into sun-protective clothing and future applications of multifunctional textiles.
Theoretical and experimental study of the diastereoisomers (2S) and (2R)-naringenin-6-C-β-D-glucopyranoside obtained from Clitoria guianensis
(2023-03-01) Cruz, Állefe Barbosa ; Ciribelli, Nicolas Nascimento ; Cunha, Camila Luiza ; Nascimento, Isabele Rodrigues ; Holzbach, Juliana Cristina ; Pereira, Douglas Henrique ; Universidade Federal do Tocantins ; Universidade Estadual Paulista (UNESP)
Abstract: In this work the diastereoisomers (2S) and (2R)-naringenin-6-C-β-D-glucopyroside, isolated for the first time from Clitoria guianensis, were studied using the density functional theory. The frontier molecular orbitals and structural properties showed that the diastereoisomers exhibit the same energy gap 166.61 kcal mol−1 and structural properties different, where in the S diastereoisomer, the bond length between the chiral carbon and the phenolic group is greater (difference of 0.0126 Å). The HPLC data showed that the retention time of the S-diastereoisomer (16.7 min) is shorter than that of R, suggesting that the S compound is more polar than R. The HPLC results corroborates with the molecular electrostatic potential which showed that in the S configuration, the electronegative density was more intense overall, particularly in the glucose molecule. The reactivity indices showed that the diastereoisomers are good electrophiles and reactive species. Finally, the absolute configuration of the diastereoisomers were determined using electronic circular dichroism (ECD) spectroscopy and the theoretical spectra were similar to the experimental. Methods: All calculations of Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) were performed using the program Gaussian 09 and the structures of the diastereoisomers were generated and analyzed using the GaussView program. The optimization and vibrational frequency calculations were performed using the functional CAM-B3LYP and 6–311 + + G(2d,2p) basis set. Conformational searches were performed for R configuration, by molecular mechanics using the MM + , MMFF, and OPLS05 force fields; the entire molecular mechanics simulation was performed using the Maestro/MacroModel software. The calculations for the simulations of the ECD spectra were performed for the eight lowest energy conformers obtained in the geometric optimization step, and the TDDFT at the CAM-B3LYP/6–311 + + G(2d,2p) theory level used. The effects of methanol and chloroform were calculated using the SMD implicit solvent model.
Self-Supported Biopolymeric Films Based on Onion Bulb (Allium cepa L.): Gamma-Radiation Effects in Sterilizing Doses
(2023-02-01) da Costa Borges, Marco Antonio ; Sorigotti, Amanda Rinaldi ; Paschoalin, Rafaella Takehara ; Júnior, José Alberto Paris ; da Silva, Lucas Henrique Domingos ; Dias, Diógenes Santos ; Ribeiro, Clóvis Augusto ; de Araújo, Elmo Silvano ; Resende, Flávia Aparecida ; da Silva Barud, Hernane ; University of Araraquara (UNIARA) ; Universidade Federal de São Carlos (UFSCar) ; Biosmart Nanotechnology ; Universidade Estadual Paulista (UNESP) ; Universidade Federal de Pernambuco (UFPE)
Sterilization is a fundamental step to eliminate microorganisms prior to the application of products, especially in the food and medical industries. γ-irradiation is one of the most recommended and effective methods used for sterilization, but its effect on the properties and performance of bio-based polymers is negligible. This work is aimed at evaluating the influence of γ-radiation at doses of 5, 10, 15, 25, 30, and 40 kGy on the morphology, properties, and performance of bioplastic produced from onion bulb (Allium cepa L.), using two hydrothermal synthesis procedures. These procedures differ in whether the product is washed or not after bioplastic synthesis, and are referred to as the unwashed hydrothermally treated pulp (HTP) and washed hydrothermally treated pulp (W-HTP). The morphological analysis indicated that the film surfaces became progressively rougher and more irregular for doses above 25 kGy, which increases their hydrophobicity, especially for the W-HTP samples. In addition, the FTIR and XRD results indicated that irradiation changed the structural and chemical groups of the samples. There was an increase in the crystallinity index and a predominance of the interaction of radiation with the hydroxyl groups—more susceptible to the oxidative effect—besides the cleavage of chemical bonds depending on the γ-radiation dose. The presence of soluble carbohydrates influenced the mechanical behavior of the samples, in which HTP is more ductile than W-HTP, but γ-radiation did not cause a change in mechanical properties proportionally to the dose. For W-HTP, films there was no mutagenicity or cytotoxicity—even after γ-irradiation at higher doses. In conclusion, the properties of onion-based films varied significantly with the γ-radiation dose. The films were also affected differently by radiation, depending on their chemical composition and the change induced by washing, which influences their use in food packaging or biomedical devices.
Synthesis and Spectroscopic Characterization of a Novel Coordination Polymer of Palladium(II) with Pyrazole and Azido Ligands
(2002-01-01) De Godoy Netto, Adelino Vieira ; Frem, Regina Célia Galvão ; Mauro, Antonio Eduardo ; Universidade Estadual Paulista (UNESP)
The one-dimensional coordination polymer of palladium(II) with pyrazolato (Pz −) and azide (N 3 −) as bridging ligands, of formula [Pd 3 (µ-N 3)(µ-Pz) 5] n, has been prepared. From IR and Raman studies it was evidenced the exobidentate nature of pyrazole ligands as well the µ-1, 1-bridging coordination of azido groups. NMR experiments showed two sets of broadened signals with different intensities indicating the presence of pyrazolato groups in distinct chemical environments. The proposed structure of [Pd 3 (µ-N 3)(µ-Pz) 5] n consisting of a zigzag ribbon in which each (Pz) 2 Pd(Pz) 2 entity is bound to two stacked planar units [Pd(µ-Pz)(µ-N 3)Pd core] with very weak Pd-Pd interaction, based on UV-Vis spectroscopy.
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.].
Closed-Vessel Conductively Heated Digestion System for the Elemental Analysis of Agricultural Materials by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry (HR-CS FAAS)
(2023-01-01) Traversa, Leonardo Clemente ; Santiago, João Victor Biagi ; de Oliveira, Evilim Martinez ; Ferreira, Edilene Cristina ; Virgilio, Alex ; Gomes Neto, José Anchieta ; Universidade Estadual Paulista (UNESP) ; Universidade de São Paulo (USP)
Novel applications of the closed-vessel conductively heated digestion system (CHDS) are proposed to digest biomass, biochar, oyster shell flour, bone meal and swine manure for the determination of Ca, K, Mg, Na, Cu, Fe, Mn, and Zn by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). The performance of the digestion method using 14 and 7 mol L−1 HNO3 was checked by analyzing soil, rock, and plant certified reference materials (CRMs). For comparative purposes, all samples were analyzed after microwave-assisted digestion (MW-AD). Results obtained for most analytes by the closed-vessel conductively heated digestion system (CHDS) were in agreement with certified values and those attained by the comparative digestion method. The use of 7 mol L−1 HNO3 furnished lower blanks for most analytes and was effective to prepare challenging samples as biomass, biochar, shell and bone meal, swine manure, plants, soil, phosphate rock, and may be a good alternative for elemental determinations using most analytical techniques that rely on solution-based sample introduction systems. The detection limits (dry basis, mg kg−1) for Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were 3, 0.4, 4, 4, 0.7, 0.4, 3, and 2, respectively. The mean relative standard deviations were close to 4.9% for closed-vessel conductively heated digestion (CHDS) and 5.9% for microwave-assisted digestion (MW-AD).
Disposable three-dimensional graphene oxide electrode with sandwich-like architecture for the determination of ascorbic acid in fruit juices
(2023-06-01) Buffon, Edervaldo ; Stradiotto, Nelson Ramos ; Universidade Estadual Paulista (UNESP)
This work reports the development of a three-dimensional graphene oxide structure on the screen-printed electrode surface for the detection of ascorbic acid. This electrode was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, RAMAN spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The present work also investigated the electrochemical behavior of ascorbic acid and its electrooxidation mechanism on the three-dimensional graphene oxide surface. The detection of ascorbic acid was conducted by linear scanning voltammetry in the concentration range from 1.0 × 10−5 to 1.0 × 10−2 mol L−1, and the limits of detection and quantification obtained for the proposed electrode were 3.4 × 10−6 and 1.1 × 10−5 mol L−1 (n = 3), respectively. The device also exhibited excellent selectivity, repeatability, reproducibility and stability. The methodology developed was applied for the determination of ascorbic acid in grape and orange juice samples with an accuracy rate ranging from 99% to 105%. These results show that the proposed electrode can be safely and reliably applied for the monitoring of ascorbic acid in fruit juices.
Understanding the Microstructure Connectivity in Photopolymerizable Aluminum-Phosphate-Silicate Sol-Gel Hybrid Materials for Additive Manufacturing
(2023-02-09) Tayama, Gabriel Toshiaki ; Santagneli, Silvia Helena ; de Oliveira Junior, Marcos ; Messaddeq, Younes ; Universidade Estadual Paulista (UNESP) ; Photonique et Laser─COPL─Universite Laval ; Universidade de São Paulo (USP)
In this paper, we report the synthesis and structural characterization of transparent and photopolymerizable aluminum-phosphate-silicate hybrid materials obtained via the sol-gel route, with different aluminum/phosphate (Al/P) ratios. We explored the system Si(1-x)-(Al/P) (x) with x varying from 0.3 to 1, and atomic ratios of Al/P are 1:3, 1:1, and 3:1. All compositions contain high inorganic mass content (up to 40 wt %). Furthermore, they are compatible with vat-photopolymerization platforms. The structural evolution of the hybrid materials with the silicon concentration was investigated by SEM, phase-contrast AFM, and solid-state NMR techniques, using single- and double-resonance experiments. The structure follows the build-up principle using aluminum-phosphate species and alkoxysilane chains as fundamental building blocks. These aluminum-phosphate species were identified as monomeric and dimeric chain structures by comparing different parameters obtained from NMR data to compound models. Monomeric and dimeric aluminum-phosphate chain structures were predominant in 3:1 and 1:3 Al/P ratio samples, respectively, promoting and hindering the heterocondensation with the alkoxysilane precursor, respectively. The photopolymerization mechanism leads to the percolation of the inorganic networks through a parallel polymethylmethacrylate network, resulting in a material with structural heterogeneities in the range of 5 nm, evidenced by phase-contrast AFM.

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