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81.
Idelma A. A. Terra Rafaela C. Sanfelice Vanessa P. Scagion Nathalia B. Tomazio Cleber R. Mendonça Luiz A. O. Nunes Daniel S. Correa 《应用聚合物科学杂志》2019,136(29):47775
Polymer nanofibers (NFs)-based optical sensors hold great potential to fabricate low-cost devices capable to monitor different volatile organic compounds (VOCs) related to healthcare and environmental conditions. For instance, ammonia detection is a subject of paramount importance, owing to the serious health problems associated to the exposition to this volatile. In this context, here, we report on the development of optical electrospun NFs composed of polyvinylpyrrolidone (PVP) doped with Europium (Eu3+) aiming at the detection of ammonia. The fabricated NFs were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, fluorescence microscopy, photoluminescence, and excited state lifetime spectroscopies. The luminescence properties changes were evaluated by exposing the PVP_Eu3+ NFs to ammonia and other distinct interfering VOCs including toluene, tetrahydrofuran, acetone, triethylamine, acetic acid, and chloroform. The sensor exhibited a linear response to ammonia exposition in the concentration range from 0 to 50 ppm, yielding a detection limit of 4.7 ppm. Our results indicate the potential application of PVP_Eu3+ electrospun NFs in optical sensors for ammonia detection at room temperature based on luminescence quenching. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47775. 相似文献
82.
Luana De Lucca de Costa Alberto Moreira Guerreiro Brito Andr Rosiak Lirio Schaeffer 《The International Journal of Advanced Manufacturing Technology》2020,107(1):39-47
Low boron steels are the only class of steel capable of forming a fully martensitic microstructure after hot stamping when a cooled tool is used, and the m 相似文献
83.
84.
Gabriella Onila do Nascimento Soares Raíssa Ribeiro Lima Machado Mariana Mendonça Diniz Aline Bruna da Silva 《Polymer Engineering and Science》2020,60(12):3231-3243
Novel cellulose acetate (CA) nanofibers incorporated with hormone progesterone (P4) were prepared by electrospinning and its potential as a controlled release system for medicine and veterinary was evaluated by controlled release essay. The morphology, thermal behavior, and structure of P4-loaded CA nanofibers were characterized by scanning electron microscopy, differential scanning calorimetry, and Fourier-transform infrared spectroscopy. The analyses revealed that the incorporation of P4 increased nanofibers' diameter from around 340 to 892 nm to 8% w/w P4-loaded CA nanofibers. Furthermore, P4 has demonstrated high interaction with CA affecting its crystalline structure, since pure CA nanofibers presented 67.23% of crystallinity while P4-loaded CA nanofibers where amorphous. Ultimately, the drug release essay demonstrated a two-stage profile, and regarding release kinetics, the samples evidenced a diffusion mechanism depending on P4 concentration in the nanofiber. 相似文献
85.
Talita Goulart da Silva Debora Baptista Pereira Beatriz Ferreira de Carvalho Patricio Michelle Alvares Sarcinelli Helvécio Vinícius Antunes Rocha Sonia Letichevsky Cristiane Evelise Ribeiro da Silva Roberta Helena Mendonça 《应用聚合物科学杂志》2021,138(28):50678
Sodium alendronate (ALD) is a bisphosphonate used to treat osteoporosis. However, its oral administration has been associated with side effects as gastroesophageal reflux. Moreover, there are some particularities for the intake of the medicine, which also hinder the patient's compliance, for example, the instruction that it has to be taken with an empty stomach, 30 to 60 min before breakfast and avoid the decubitus position after using the drug. Therefore, biomaterials for applications in osteoporotic bones are a good alternative. Thus, this work aimed to produce a Polycaprolactone (PCL) and ALD-based powder as a supply to build biomaterials by selective laser sintering, compression molding (CM), solvent casting (SC), among others. The powder was produced by coating the ALD particles with PCL and films were produced by SC and CM techniques. The samples were characterized by Scanning Electron Microscopy, Energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectrometry and thermal analysis. Furthermore, the drug release was evaluated by UV–Vis spectroscopy. Results showed that ALD particles were successfully coated by PCL and applied to the production of biomaterials, highlighting its potential in the treatment of osteoporosis. 相似文献
86.
Luana Roleto Cardoso Flvia Emi Razera Baldasso Dbora Delai Francisco Montagner Patrícia Maria Poli Kopper 《Microscopy research and technique》2019,82(2):128-133
This study evaluated the influence of canal irrigation protocols with 5.25% calcium hypochlorite [Ca(OCl)2], 5.25% sodium hypochlorite (NaOCl) and 17% EDTA solution on the inorganic component of root canal dentin. Sixty roots were randomly divided into six groups (n = 10): Saline solution (SS) (control); Saline solution (SSE) +17% EDTA; CH ? 5.25% Ca(OCl)2; CHE ? 5.25% Ca(OCl)2 + 17% EDTA; SH ? 5.25% NaOCl; SHE ? 5.25% NaOCl +17% EDTA. After canal irrigation, the specimens were longitudinally split and analyzed by scanning electron microscopy (SEM). Dentinal tubules were observed in transverse (middle and apical thirds) direction. The images were classified in scores, according to smear layer removal and peritubular dentin alteration, and data were analyzed by Kruskal–Wallis's test, followed by Dunn's test (α = 0.05). In the middle third, all groups with EDTA presented better removal of the smear layer with higher peritubular dentin alteration (p < .05). In the apical third, this happened only in SHE (p < .05). Ca(OCl)2 and NaOCl exhibit similar performance to remove smear layer and alteration of the inorganic component in the middle third. In the apical third, NaOCl associated with EDTA showed better performance in smear layer removal. 相似文献
87.
The present study investigated the presence of ryanodine receptors in the trematode Schistosoma mansoni. [3H]Ryanodine specific binding sites were found in the four subcellular fractions of S. mansoni; however, more binding sites were recovered in the heterogeneous fraction P1 and the microsomal fraction P4, as was thapsigargin-sensitive (Ca2+-Mg2+)ATPase activity, marking the sarco/endoplasmic reticulum calcium ATPase (SERCA) pumps. This binding had an equilibrium dissociation constant (Kd) in the nanomolar range, an apparent maximal number of receptors (Bmax) of about 80 fmol/mg of protein, and was modulated by ions (Ca2+, Mg2+) and some pharmacological tools such as caffeine. Ryanodine was able to accelerate the rate of 45Ca2+ release from actively loaded vesicles, and also to induce a transient contraction of the whole worm. We conclude that ryanodine-sensitive Ca2+ release channels are present in S. mansoni, with properties very similar to the ones present in higher animals. 相似文献
88.
Rafaela C. Sanfelice Luiza A. Mercante Adriana Pavinatto Nathália B. Tomazio Cleber R. Mendonça Sidney J. L. Ribeiro Luiz H. C. Mattoso Daniel S. Correa 《Journal of Materials Science》2017,52(4):1919-1929
Conjugated polymers have been extensively applied as active materials in nanostructured platforms for optical and electrical devices. The incorporation of metal nanoparticles (NPs) into the polymer-based platform arises as a strategy to develop novel hybrid functional nanocomposites with enhanced electrical and optical properties. However, efficient and simple processing routes to produce such nanocomposites are still on demand. In this work, we present an effective route to obtain functional nanocomposites based on electrospun nanofibers coated with gold nanoparticles, displaying interesting optical and electrical properties. Polymethyl methacrylate (PMMA) electrospun nanofibers doped with poly(3-hexyl thiophene-2,5-diyl) (P3HT) were obtained by the electrospinning technique, and displayed a strong red emission centered at 650 nm assigned to P3HT. Such nanofibers were deposited on to fluorine-doped tin oxide electrodes and with modified with gold nanoparticles (AuNPs) in order to produce hybrid composite materials. The performance of electrodes modified with PMMA/P3HT-AuNPs composite material was evaluated by impedance spectroscopy and revealed an enhancement of electron transfer kinetics, which indicates it as a potential platform for optical and electrochemical (bio)sensors. 相似文献
89.
Shear Piezoelectricity in Poly(vinylidenefluoride‐co‐trifluoroethylene): Full Piezotensor Coefficients by Molecular Modeling,Biaxial Transverse Response,and Use in Suspended Energy‐Harvesting Nanostructures 下载免费PDF全文
90.
Natalia Cadavid Muñoz Luana Floriano Maiara P. de Souza Nelson M. G. Bandeira Osmar D. Prestes Renato Zanella 《Food Analytical Methods》2017,10(2):320-329
A fast and effective multiresidue method for the determination of 42 pesticides in golden berry was developed and validated. A modified QuEChERS method was established for sample preparation followed by ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) determination with electrospray ionization in a triple quadrupole system. Validation results were satisfactory, since the method presented recoveries between 70 and 114 % with relative standard deviations (RSD) <20 % for blank samples spiked from 5 to 25 μg kg?1. The method limit of detection and limit of quantification were 1.5 and 5 μg kg?1 , respectively. Matrix effect ranged from ?32 to 218 % and was compensated using matrix-matched calibration. Method linearity was established from 2.5 to 100 μg kg?1 with r 2 ≥ 0.99. The proposed method combines the advantages of a simple and fast sample preparation step by a modified QuEChERS method with the high selectivity and sensitivity of the UHPLC-MS/MS system using selected reaction monitoring. The method was successfully applied to commercial samples, proving to be an efficient alternative for routine analysis. From the 16 analyzed samples, 13 presented residues of one or more pesticides (carbendazim, chlorpyrifos ethyl, dimethoate, propamocarb, and tebuconazole) in the concentration range of 2.0 to 55.6 μg kg?1. 相似文献