Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Heliyon ; 9(7): e17977, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37539112

RESUMO

In this work, a new and effective polymeric coating is used to improve mild steel's corrosion resistance. The coating incorporates a Schiff base moiety into a benzoxazine (BZ) precursor, resulting in improved protection against corrosion. The SF-Tol-BZ polymerization behavior and thermal properties were studied using differential scanning calorimetry (DSC) and thermalgravimetric analysis (TGA), respectively, at different curing temperatures. The poly(SF-Tol-BZ) cured at 240 °C had a Td10 value of 604 °C and a Tg of 225 °C. The efficacy of poly(SF-Tol-BZ) coatings in protecting mild steel (MS) from corrosion in a NaCl (3.5%) solution at room temperature was evaluated using various corrosion measurements, including open circuit potential (OCP), and electrochemical impedance spectroscopy (EIS). The results showed that increasing the poly(SF-Tol-BZ) concentration led to a corresponding increase in its protective efficiency, reaching a maximum of 92% at a concentration of 300 g/L. The coatings also exhibited a 24-fold increase in Rct values and a one-order-of-magnitude reduction in CPE compared to the bare mild steel. Finally, the poly(SF-Tol-BZ) precursors demonstrated a CO2 uptake of 23 mg g-1 (measured at 298 K).

2.
BMC Chem ; 17(1): 77, 2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37454143

RESUMO

Modifying the metal surface is one solution to the industry's growing corrosion problem. Thus, via threading approach and insertion of copolymers (CoP5-7) containing polyarylidenes through the internal cavity beta-cyclodextrin ß-CD, novel pseudopolyrotaxanes copolymers (PC5-7) are developed, resulting in mild steel corrosion inhibition. Inhibitors of corrosion based on ß-CD molecules adsorb strongly to metal surfaces because of their many polar groups, adsorption centers, many linkages of side chains, and benzene rings. The corrosion inhibition efficiencies IE % statistics have been revised via the Tafel polarization method and Spectroscopy based on the electrochemical impedance (EIS), with PC7 achieving the highest 99.93% in 1.0 M H2SO4; they are mixed-type inhibitors. The chemical composition of the resulting PCs is determined with Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) is utilized to examine the morphological structure of the produced polymers, and X-ray diffraction is employed to identify crystallinity. Encapsulating CoP5-7 with ß-CD changes the morphological structures and increases the generated PCs' crystallinity. The thermal stability of PCs is studied, indicating the presence of these CoPs within the ß-CD cavities enhances their thermal stability. This research will be a stepping stone for developing high-efficiency anti-corrosion coatings and various industrial applications.

3.
Heliyon ; 9(5): e15976, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37215883

RESUMO

In this study, we utilized salicylaldehyde (SA) and p-toluidine (Tol-NH2) to synthesize 2-(Z)[(4-methylphenyl)imino]methylphenol (SA-Tol-SF), which was then reduced to 2-[(4-methylphenyl)amino]methylphenol, producing SA-Tol-NH. SA-Tol-NH was further reacted with formaldehyde to create SA-Tol-BZ monomer. Poly(SA-Tol-BZ) was produced by thermally curing it at 210 °C, after synthesizing it from SA-Tol-BZ. The chemical structure of SA-Tol-BZ was analyzed using various analytical techniques such as FT-IR, 1H NMR spectroscopy, and 13C NMR spectroscopy TGA, SEM, DSC, and X-ray analyses. Afterward, we applied the obtained poly(SA-Tol-BZ) onto mild steel (MS) using thermal curing and spray coating techniques. To examine the anticorrosion attributes of MS coated with poly(SA-Tol-BZ), electrochemical characterization was employed. The study proved that poly(SA-Tol-BZ) coating had a high level of effectiveness in preventing corrosion on MS, with an efficacy of 96.52%, and also exhibited hydrophobic properties.

4.
Sci Rep ; 13(1): 5581, 2023 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-37019919

RESUMO

In this study, 2-[(E)-(hexylimino)methyl] phenol (SA-Hex-SF) was synthesized by adding salicylaldehyde (SA) and n-hexylamine (Hex-NH2), which was subsequently reduced by sodium borohydride to produce 2-[(hexylamino)methyl] phenol (SA-Hex-NH). Finally, the SA-Hex-NH reacted with formaldehyde to give a benzoxazine monomer (SA-Hex-BZ). Then, the monomer was thermally polymerized at 210 °C to produce the poly(SA-Hex-BZ). The chemical composition of SA-Hex-BZ was examined using FT-IR, 1H, and 13C NMR spectroscopy. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and X-ray Diffraction (XRD), respectively, were used to examine the thermal behavior, surface morphology, and crystallinity of the SA-Hex-BZ and its PBZ polymer. Mild steel (MS) was coated by poly(SA-Hex-BZ) which was quickly prepared using spray coating and thermal curing techniques (MS). Finally, the electrochemical tests were used to evaluate the poly(SA-Hex-BZ)-coating on MS as anti-corrosion capabilities. According to this study, the poly(SA-Hex-BZ) coating was hydrophobic, and corrosion efficiency reached 91.7%.

5.
Sci Rep ; 12(1): 16317, 2022 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-36175463

RESUMO

This study aims to develop an alternating polyketone containing cationic groups in one and four alternating positions for increased functionality. A novel polyarylidene ketone was synthesized using simple condensation polymerization of terephthaldehyde and 2,5-hexane dione (PAK) The physicochemical properties of the resulting polymer were evaluated using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, UV-Visible absorbance, fluorescence, and SEM investigations. The findings show that the polymer is amorphous, has good thermal stability, and emits red light. It can also be used as a dye adsorbent in aqueous solutions, with high selectivity for the cationic dye methylene blue (MB). The adsorbent efficiency of PAK was measured as a function of pH, dosage, and initial dye concentration; the greatest dye removal of 96 % was obtained at pH 10, 50 mg dosage, and initial dye concentration of 20 ppm. Kinetics and isotherms were studied, showing that the pseudo-second-order model described kinetic data better than Freundlich and Langmuir and revealed a satisfactory chemisorption process. This study suggests that PAK can purify MB dyeing wastewater, remove Zn2+, Cu2+, Ni2+, Co2+, Cd2+, Fe3+ metal ions well, and is selective for Fe3+ and Cu2+; ion adsorption is chelating-based.


Assuntos
Hexanos , Azul de Metileno , Adsorção , Cádmio , Corantes , Cetonas , Águas Residuárias
6.
Sci Rep ; 12(1): 12878, 2022 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-35896584

RESUMO

To develop innovative mesoporous crosslinked poly(azomethine- sulfone)s with environmental applications, a simple Schiff base condensation technique based on barbituric acid BA or condensed terephthaldehyde barbituric acid TBA in their structures as monomeric units are applied. Different analysis methodologies and viscosity measurements identify them as having stronger heat stability and an amorphous structure. The photophysical features of the multi stimuli response MSR phenomenon are observable, with white light emission at higher concentrations and blue light emission at lower concentrations. Their emission characteristics make them an excellent metal ions sensor through diverse charge transfer methods. They can have a better inhibition efficiency and be employed as both mixed-type and active corrosion inhibitors according to their fluorescence emission with metals, demonstrating their capacity to bind with diverse metals. The adsorption of two distinct dye molecules, Methylene blue MB cationic and sunset yellow SY anionic, on the mesoporous structures of the polymers is investigated, revealing their selectivity for MB dye adsorption. Quantum studies support these amazing discoveries, demonstrating a crab-like monomeric unit structure for the one that is heavily crosslinked.


Assuntos
Corantes , Azul de Metileno , Adsorção , Compostos Azo , Corantes/química , Azul de Metileno/química , Porosidade , Sulfonas , Tiossemicarbazonas
7.
J Pediatr Surg ; 56(11): 1982-1987, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33573805

RESUMO

BACKGROUND/ PURPOSE: Elective resection of congenital lung malformations (CLMs) is still debatable. The two main risks are malignant transformation and recurrent pulmonary infections. Our study aimed to assess the effect of previous pulmonary infection on the intraoperative and postoperative courses of thoracoscopic surgery for CLMs. METHODS: This is a retrospective study including all thoracoscopic lung resections for CLMs between 2010 and 2019. Ninety patients were included. There was a history of previous pulmonary infection in 28 patients (group A) and no such history in 62 patients (group B). RESULTS: The median age at operation for group A was 20.4 months (IQR:14.9-41.4) versus 15.1 months (IQR:9.7-20.8) in group B (p = 0.006). There were 10 conversions (35.7%) in group A and 8 (12.9%) in group B (p = 0.02). The operative time was significantly shorter in group B (p<0.002). In group A, 32.1% of patients experienced postoperative fever versus 11.3% of group B (p = 0.03), with higher antibiotics requirement (28.6% versus 6.5% respectively, p = 0.007). However, no significant differences were found in terms of postoperative complications (p = 0.99). CONCLUSION: Earlier intervention for CLMs before the development of pulmonary infection carries higher chances for the success of the thoracoscopic approach with shorter operative time and more uneventful postoperative courses.


Assuntos
Malformação Adenomatoide Cística Congênita do Pulmão , Malformação Adenomatoide Cística Congênita do Pulmão/cirurgia , Humanos , Lactente , Pulmão/cirurgia , Pneumonectomia , Estudos Retrospectivos , Toracoscopia , Resultado do Tratamento
8.
J Laparoendosc Adv Surg Tech A ; 30(12): 1289-1294, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33155851

RESUMO

Background/Objective: Thoracoscopic repair of esophageal atresia (EA) is gaining popularity, but it is a highly technically demanding procedure. The aim of our study is to evaluate our outcomes in the management of type C EA comparing the thoracoscopic and the open (thoracotomy) approaches. Methods: This is a retrospective bicentric study of two major pediatric surgery centers, reviewing all the patients operated for EA with distal tracheoesophageal fistula. Only patients who underwent primary anastomosis were included. From 2008 to 2018, 187 patients were included. Results: Forty-seven patients were operated thoracoscopically (TS group) and 140 by the open approach (TT group). Mean gestational age was 38 ± 2.4 weeks in TS group and 36.4 ± 3.3 weeks in TT group (P = .005) with a mean birth weight of 2785 ± 654 g and 2404.9 ± 651 g in TS and TT groups, respectively (P = .003). The mean operative time was 127.6 ± 35 minutes in TS group and 105.7 ± 23 minutes in TT group (P = .0005). The mean postoperative ventilation time and the mean length of stay were significantly shorter in the thoracoscopic group (P = .004 and P < .0001, respectively). The incidence of anastomotic leak was 8.9% in TS group versus 16.4% in TT group (P = .33). Anastomotic stenosis occurred in 33.3% of TS group and in 22.4% of TT group (P = .17). Conclusions: Surgical outcome of thoracoscopic repair of EA is comparable to the open repair with no higher complication rate with the expected skeletal and cosmetic benefits. However, possible bias regarding prematurity, weight at surgery, and associated anomalies must be taken into consideration.


Assuntos
Atresia Esofágica/cirurgia , Toracoscopia/métodos , Toracotomia/métodos , Fístula Traqueoesofágica/cirurgia , Anastomose Cirúrgica , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Duração da Cirurgia , Período Pós-Operatório , Estudos Retrospectivos , Resultado do Tratamento
9.
Front Pediatr ; 8: 426, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32984197

RESUMO

Background/Purpose: Laparoscopic pyloromyotomy gained wide popularity in management of pyloric stenosis with contradictory results regarding its benefits over classic open approach. This study aimed at comparing both regarding their safety, efficiency, and outcome. Methods: This is a prospective randomized controlled study performed from April 2017 to April 2019. It included 80 patients, divided randomly into two groups, where laparoscopic pyloromyotomy was performed in group A and open pyloromyotomy in group B. Both groups were compared regarding operative time, post-operative pain score, time required to reach full feeding, hospital stay, complications, and parents' satisfaction. Results: Median operative time was 21 min in group A vs. 30 min in group B (P = 0). Pain Assessment in Neonates scores were generally higher in group B with more doses of analgesics required (P = 0). Mean time needed to reach full feeding was 15.2 and 18.8 h in groups A and B, respectively (P = 0). Median hospital stay was 19 h in group A and 22 h in group B (P = 0.004). Parents' satisfaction also was in favor of group A (P = 0.045). Although no significant difference was reported between both groups regarding early and late complications, some complications such as mucosal perforation and incomplete pyloromyotomy occurred in the laparoscopic group only. Conclusion: Laparoscopic pyloromyotomy was found superior to open approach regarding faster operative time, less need of analgesics, easier development of oral feeding, shorter hospital stay, and better parents' satisfaction. Yet, there are still some concerns about the safety and efficiency of this procedure over open technique.

10.
Des Monomers Polym ; 21(1): 82-98, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29844770

RESUMO

A new category of thermally stable hybrid polyarylidene(azomethine-ether)s and copolyarylidene(azomethine-ether)s (PAAP) based on diarylidenecycloalkanones has been synthesized using solution polycondensation method. For potential cationic sensor development, a thin layer of PAAP onto a flat glassy carbon electrode (GCE, surface area: 0.0316 cm2) was prepared with conducting nafion (5%) coating agent to fabricate a sensitive and selective arsenic (III) [As3+] ion in short response time in neutral buffer system. The fabricated cationic sensor was measured the analytical performances such as higher sensitivity, linear dynamic range, detection limit, reproducibility, and long-term stability towards As3+ ions. The sensitivity and detection limit were calculated as 2.714 µAµM-1cm-2 and 6.8 ± 0.1 nM (SNR of 3; 3N/S) respectively from the calibration curve. This novel approach can be initiated a well-organized route of an efficient development of heavy selective arsenic sensor for hazardous pollutants in biological, environmental, and health care fields. Real sample analysis for various environmental sample was performed with PAAP-modified-GCE.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...