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1.
Clin Sci (Lond) ; 131(15): 1831-1840, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28572401

RESUMO

Polymorphism in the ABCB1 gene encoding P-glycoprotein, a transmembrane drug efflux pump, contributes to drug resistance and has been widely studied. However, their association with rifampicin and ethambutol resistance in tuberculosis (TB) patients is still unclear. Genotype/allele/haplotype frequencies in c.1236C > T (rs1128503), c.2677G > T/A (rs2032582), and c.3435C > T (rs1045642) were obtained from 218 patients. Of these, 80 patients with rifampicin and/or ethambutol resistance were selected as the case group and 138 patients were selected for the control group through the results of their culture and drug-sensitive tests. Patients aged <18 years and HIV-positive serologic tests were excluded. ABCB1 polymorphisms were determined using a PCR direct-sequencing approach, and restriction fragment length polymorphism (RFLP). A nomogram was constructed to simulate a combined prediction of the probability of anti-TB drug resistance, with factors including genotype c.1236C > T (rs1128503) (P=0.02), clinical form (P=0.03), previous treatment (P=0.01), and skin color (P=0.03), contributing up to 90% chance of developing anti-TB drug resistance. Considering genotype analyses, CT (rs1128503) demonstrated an increased chance of anti-TB drug resistance (odds ratio (OR): 2.34, P=0.02), while the analyses for ethambutol resistance revealed an association with a rare A allele (rs2032582) (OR: 12.91, P=0.01), the haplotype TTC (OR: 5.83, P=0.05), and any haplotype containing the rare A allele (OR: 7.17, P=0.04). ABCB1 gene polymorphisms in association with others risk factors contribute to anti-TB drug resistance, mainly ethambutol. The use of the nomogram described in the present study could contribute to clinical decision-making prior to starting TB treatment.


Assuntos
Polimorfismo de Nucleotídeo Único , Tuberculose Resistente a Múltiplos Medicamentos/genética , Subfamília B de Transportador de Cassetes de Ligação de ATP/genética , Adulto , Idoso , Antituberculosos/uso terapêutico , Estudos de Casos e Controles , Farmacorresistência Bacteriana Múltipla/genética , Etambutol/uso terapêutico , Feminino , Frequência do Gene , Genótipo , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Mycobacterium tuberculosis/efeitos dos fármacos , Nomogramas , Valor Preditivo dos Testes , Rifampina/uso terapêutico , Fatores de Risco , Tuberculose Resistente a Múltiplos Medicamentos/tratamento farmacológico , Adulto Jovem
2.
J Environ Sci Health B ; 51(12): 817-823, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27494596

RESUMO

The aim of this study was to investigate the relationship between antibiotic residues found in the muscle of cage-farm-raised Nile tilapia (Oreochromisniloticus), the occurrence of resistant bacteria, and the sanitary practices adopted by farmers in Ilha Solteira reservoir, Brazil. Nine fish (three small fish, 40-200 g; three medium-sized fish, 200-500 g; and three large fish, 500-800 g) were collected from four cage farms every three months from April 2013 to January 2014. Ten antibiotic residues were determined using liquid chromatography-mass spectrometry, and bacteria were isolated and tested for antibiotic resistance to determine the multiple antibiotic resistance (MAR) index. Only three antibiotics (oxytetracycline, tetracycline, and florfenicol) were detected in the muscle of Nile tilapia, and their residues were the highest in small fish; however, the MAR index was higher in large fish. In addition, a direct positive relationship between the MAR index and the concentration of antibiotic residues in Nile tilapia was found. Overall, the adoption of prophylactic management practices improved the sanitary status of cage farms, reducing bacterial infections and hampering the development of antibiotic-resistant bacteria.


Assuntos
Antibacterianos/análise , Aquicultura , Bactérias/efeitos dos fármacos , Ciclídeos/microbiologia , Farmacorresistência Bacteriana , Animais , Bactérias/isolamento & purificação , Brasil , Fazendas , Músculo Esquelético/química , Músculo Esquelético/microbiologia , Oxitetraciclina/análise , Tetraciclina/análise
3.
J Environ Sci Health B ; 51(9): 634-43, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27249158

RESUMO

An on-line solid phase extraction liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) method for the determination of 12 antimicrobials in sediment and surface water was developed and validated. Furthermore, the spatial and temporal antimicrobials distributions in the sediment and in the water of four fish farms located in the hydroelectric dam of Ilha Solteira Reservoir in Brazil were investigated over four seasons in three sampling sites: at the fish cages, 100 and 1,000 m downstream far from the cages. The method was performed using an Agilent Zorbax 80 SB-C8 column (9.4 × 15 mm, 5 µm) as the loading column, and the Agilent Zorbax Eclipse Plus C18 column (3.0 × 100 mm, 3.5 µm) as a separation column within a run time of 13 min. The limits of quantification were less than 9 ng·L(-1) for the antibiotics in water and 16 µg·kg(-1) in sediment; the recovery ranged from 80 to 119%, with a variation coefficient less than 11%, and the repeatability was lower than 15%. Oxytetracycline was found in the water in all sample seasons. However, florfenicol was identified in April and October 2013 and January 2014, and tetracycline was present in July 2013. Regarding the sediment, oxytetracycline and tetracycline were found in all sampling periods, but chlortetracycline was only identified in January 2014. The spatial distribution of antimicrobials showed that the main pollution source came from the fish farms. This study demonstrated that the proposed method is reliable for the monitoring of antimicrobials in water and sediments and it showed contamination in both matrices from Ilha Solteira Reservoir.


Assuntos
Antibacterianos/análise , Monitoramento Ambiental/métodos , Pesqueiros , Sedimentos Geológicos/química , Poluentes Químicos da Água/análise , Água/química , Brasil , Cromatografia Líquida/métodos , Estações do Ano , Extração em Fase Sólida/métodos , Análise Espaço-Temporal , Espectrometria de Massas em Tandem/métodos , Fatores de Tempo
4.
Polymers (Basel) ; 16(17)2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39274067

RESUMO

This investigation explores the fabrication of polymer matrix nanocomposites via additive manufacturing (AM), using a UV photopolymerization resin and copper nanoparticles (Cu-NPs) with vat photopolymerization 3D printing technology. The aim in this study is to investigate the mentioned materials in different formulations in terms of inexpensive processing, the property related variability, and targeting multifunctional applications. After the AM process, samples were post-cured with UV light in order to obtain better mechanical properties. The particles and resin were mixed using an ultrasonicator, and the particle contents used were 0.0, 0.5, and 1.0 wt %. The process used in this investigation was simple and inexpensive, as the technologies used are quite accessible, from the 3D printer to the UV curing device. These formulations were characterized with scanning electron microscopy (SEM) to observe the materials' microstructure and tensile tests to quantify stress-strain derived properties. Results showed that, besides the simplicity of the process, the mixing was effective, which was observed in the scanning electron microscope. Additionally, the tensile strength was increased with the UV irradiation exposure, while the strain properties did not change significantly.

5.
Polymers (Basel) ; 16(2)2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38257043

RESUMO

Additive manufacturing has garnered significant attention as a versatile method for fabricating green and complex composite materials. This study delves into the fabrication of polymer composites by employing polylactic acid (PLA) in conjunction with rice husk as a reinforcing filler. The filaments were made by an extruded filament maker and then were used to make tensile and impact samples by another extrusion technology, fused deposition modeling (FDM). The structural and morphological characteristics of the composite materials were analyzed using scanning electron microscopy SEM. Results show that both the filament and samples are very reliable in producing polymer parts with this rice husk solid waste. This research contributes to increasing materials' circularity and potentially creating a local social economy around rice production, where this waste is not much used.

6.
Polymers (Basel) ; 16(7)2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38611171

RESUMO

The mechanical and ballistic performance of epoxy matrix composites reinforced with 10, 20, and 30 vol.% of babassu fibers was investigated for the first time. The tests included tension, impact, and ballistic testing with 0.22 caliber ammunition. The results showed an improvement in tensile strength, elastic modulus, and elongation with the addition of babassu fiber, and the 30 vol.% composite stood out. Scanning electron microscopy analysis revealed the fracture modes of the composites, highlighting brittle fractures in the epoxy matrix, as well as other mechanisms such as fiber breakage and delamination in the fiber composites. Izod impact tests also showed improvement with increasing babassu fiber content. In ballistic tests, there was an increase in absorbed energy. All composites surpassed plain epoxy by over 3.5 times in ballistic energy absorption, underscoring the potential of babassu fiber in engineering and defense applications.

7.
Polymers (Basel) ; 16(3)2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38337203

RESUMO

With its extensive production and consumption, the coffee industry generates significant amounts of lignocellulosic waste. This waste, primarily comprising coffee biomasses, is a potential source of cellulose. This cellulose can be extracted and utilized as a reinforcing agent in various biocomposites with polymer matrices, thereby creating high-value products. One such biodegradable polymer, Poly(butylene adipate-co-terephthalate) (PBAT), is notable for its properties that are comparable with low-density polyethylene, making it an excellent candidate for packaging applications. However, the wider adoption of PBAT is hindered by its relatively high cost and lower thermomechanical properties compared with conventional, non-biodegradable polymers. By reinforcing PBAT-based biocomposites with cellulose, it is possible to enhance their thermomechanical strength, as well as improve their water vapor and oxygen barrier capabilities, surpassing those of pure PBAT. Consequently, this study aims to provide a comprehensive review of the latest processing techniques for deriving cellulose from the coffee industry's lignocellulosic by-products and other coffee-related agro-industrial wastes. It also focuses on the preparation and characterization of cellulose-reinforced PBAT biocomposites.

8.
Sci Rep ; 14(1): 6421, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38494529

RESUMO

The use of natural fibers in cementitious composites has been gaining prominence in engineering. The natural lignocellulosic fibers (NLFs) used in these composites have advantages such as reduced density, reduced fragmentation and concrete cracking, thus improving flexural performance and durability. Coconut-fiber is one of those natural fibers and its use presents technical, ecological, social and economic benefits, as it is improperly disposed of, representing a large waste of natural resources, in addition to causing environmental pollution.. Thus, composites reinforced with natural fibers are promising materials for the construction industry, as in addition to meeting the sustainability of buildings, there will also be a reduction in urban solid waste generated and gains for structures with the use of environmentally friendly materials that meet to active efforts and with greater durability. This work aims to evaluate the tensile behavior of green coconut-fibers subjected to different drying temperatures through chemical, thermal (TG/DSC), morphological, visual and mechanical analysis. Drying temperatures of 70 °C, 100 °C and 130 °C were analyzed and the results indicated that the drying temperature at 70 °C was satisfactory, providing fiber-reinforced composites with good tensile strength, combined with good ductility.

9.
Food Addit Contam Part B Surveill ; 17(3): 275-285, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38992977

RESUMO

Levels of 237 pesticides were assessed in 1063 fruit and vegetable samples from 12 São Paulo markets spanning the period May 2015 to December 2022. The QuEChERS method was employed for extraction, followed by GC-MS/MS and LC-MS/MS analysis. Findings indicated that 30% of the samples contained residues below the Maximum Residue Limits (MRLs), while 6% exceeded these. Additionally, 23% exhibited excessive residues for their respective crops and 40% had no detectable residues. Health risk evaluation focused on tomatoes, cabbage and oranges, revealing exposure within 0.002-0.9% of the Acceptable Daily Intake (ADI), indicating no chronic risks. However, pyraclostrobin in orange presented a potential acute risk for adults (112%). These results underscore the necessity for continuous monitoring of pesticide residues in fruits and vegetables to safeguard consumer health, especially considering the significant levels of consumption.


Assuntos
Contaminação de Alimentos , Frutas , Resíduos de Praguicidas , Espectrometria de Massas em Tandem , Verduras , Frutas/química , Verduras/química , Brasil , Medição de Risco , Resíduos de Praguicidas/análise , Contaminação de Alimentos/análise , Humanos , Praguicidas/análise , Adulto , Cromatografia Gasosa-Espectrometria de Massas
10.
Materials (Basel) ; 17(9)2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38730781

RESUMO

In the present work, the influence of a corrosive environment and temperature on the corrosion resistance properties of duplex stainless steel S31803 was evaluated. The corrosive process was carried out using solutions of 1.5% HCl (m/m) and 6% FeCl3 (m/m), at temperatures of 25 and 50 °C. The microstructure of UNS S31803 duplex stainless steel is composed of two phases, ferrite and austenite, oriented in the rolling direction, containing a ferrite percentage of 46.2% in the rolling direction and 56.1% in the normal direction. Samples, when subjected to corrosive media and temperature, tend to decrease their mechanical property values. It was observed, in both corrosive media, that with increasing test temperature, there is an increase in the corrosion rate, both uniform and pitting. The sample in HCl solution obtained a uniform corrosion rate of 0.85% at 25 °C and 0.92% at 50 °C and pitting rates of 0.77% and 1.47% at the same temperatures, respectively. When tested in FeCl3 solution, it obtained uniform corrosion of 0.0006% and 0.93% and pitting of 0.53% and 18.5%, at the same temperatures. A reduction in dissolution potentials is also noted, thus characterizing greater corrosion in the samples with increasing temperature.

11.
Polymers (Basel) ; 16(14)2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-39065380

RESUMO

The use of mineral reinforcements in polymer matrix composites has emerged as an alternative for sustainable production, reducing waste and enhancing the physical and mechanical properties of these materials. This study investigated the impact of the melt flow index (MFI) of HDPE and the particle size of two mineral reinforcements, Bahia Beige (BB) and Rio Grande do Norte Limestone (CRN), on the composites. All composites were processed via extrusion, followed by injection, with the addition of 30 wt.% reinforcement. Chemical analyses revealed similar compositions with high CaO content for both minerals, while X-ray diffraction (XRD) identified predominantly calcite, dolomite, and quartz phases. Variations in the MFI, reinforcement type, and particle size showed a minimal influence on composite properties, supported by robust statistical analyses that found no significant differences between groups. Morphological analysis indicated that composites with lower MFI exhibited less porous structures, whereas larger particles of BB and CRN formed clusters, affecting impact resistance, which was attributed to poor interfacial adhesion.

12.
Materials (Basel) ; 17(18)2024 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-39336247

RESUMO

Tensile perpendicular to grain is an important mechanical property in the design of joints in timber structures. However, according to the standards, this strength can be determined using at least two different methods: uniaxial tensile and three-point static bending. In this context, the present paper aims to investigate the influence of these test methods on the determination of tensile strength perpendicular to grain of wood used in civil construction timber. Three wood species from Brazilian planted forests (Pinus spp., Eucalyptus saligna, and Corymbia citriodora) were used in this investigation. Twelve specimens of each species were used for each test method investigated. Moreover, a statistical analysis was performed to propose an adjustment to the equation of the Code of International Organization for Standardization 13910:2014 for the three-point bending test. Tensile strength values perpendicular to grain obtained from the uniaxial tensile test were significantly higher than those determined by the three-point bending test. It is proposed that the tensile strength perpendicular to grain can be determined more precisely with adoption of coefficient 5.233 in the term [(3.75·Fult)/b·Lh] of the equation specified by the Code of International Organization for Standardization 13910:2014 for the three-point bending test.

13.
Medicina (B Aires) ; 73(6): 529-34, 2013.
Artigo em Espanhol | MEDLINE | ID: mdl-24356261

RESUMO

Myotonic dystrophy (DM) is the most common dystrophy in adults. Several factors may explain the chronic CO2 retention. The selection of patients, different clinical stages and evaluation forms may explain the differing results obtained. Our objectives were to characterize respiratory function and to evaluate factors associated with chronic retention of CO2 in DM. We included 27 consecutive ambulatory and stable patients who were allocated into normocapnic and hypercapnic groups (PaCO2 ≥ 43 mmHg). Forced vital capacity (FVC), maximum static pressure, voluntary apnea time, Epworth scale and arterial blood gases were measured. The CO2 chemosensitivity was assessed using CO2 rebreathing (Read method). The slope ΔP0.1/ΔPCO2 expressed the CO2 chemosensitivity. A 59.3% (16/27) presented hypercapnia. FVC and respiratory muscle strength were normal or showed mild to moderate decrease. No significant differences in these variables were found in both groups. Inadequate response to CO2 (slope ΔP0.1/ΔPCO2 low (< 0.1 cm H2O/mmHg) or flat) was associated with hypercapnia (p < 0.005). Chronic retention of CO2 represented 11.56 times higher risk of inadequate response to CO2. The group with low-flat slope ΔP0.1/ΔPCO2 showed higher PaCO2 (p = 0.0017) and more prolonged voluntary apnea time (p = 0.002). We conclude that in our patients with DM, chronic CO2 retention was associated with the presence of abnormalities of the central control of breathing. Our results allow explaining previous reports describing the striking frequency of postoperative respiratory failure and difficulties in the process of weaning from mechanical ventilation.


Assuntos
Dióxido de Carbono/sangue , Hipercapnia/complicações , Distrofia Miotônica/complicações , Adulto , Apneia/patologia , Doença Crônica , Distúrbios do Sono por Sonolência Excessiva/complicações , Feminino , Volume Expiratório Forçado , Humanos , Hipercapnia/sangue , Masculino , Pessoa de Meia-Idade , Transtornos Respiratórios/sangue , Transtornos Respiratórios/complicações , Testes de Função Respiratória , Espirometria/métodos , Capacidade Vital , Adulto Jovem
14.
Polymers (Basel) ; 15(2)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36679253

RESUMO

The global orthopedic market is forecasted to reach US$79.5 billion by the end of this decade. Factors driving the increase in this market are population aging, sports injury, road traffic accidents, and overweight, which justify a growing demand for orthopedic implants. Therefore, it is of utmost importance to develop bone implants with superior mechanical and biological properties to face the demand and improve patients' quality of life. Today, metallic implants still hold a dominant position in the global orthopedic implant market, mainly due to their superior mechanical resistance. However, their performance might be jeopardized due to the possible release of metallic debris, leading to cytotoxic effects and inflammatory responses in the body. Poly (ether-ether-ketone) (PEEK) is a biocompatible, high-performance polymer and one of the most prominent candidates to be used in manufacturing bone implants due to its similarity to the mechanical properties of bone. Unfortunately, the bioinert nature of PEEK culminates in its diminished osseointegration. Notwithstanding, PEEK's bioactivity can be improved through surface modification techniques and by the development of bioactive composites. This paper overviews the advantages of using PEEK for manufacturing implants and addresses the most common strategies to improve the bioactivity of PEEK in order to promote enhanced biomechanical performance.

15.
Polymers (Basel) ; 15(19)2023 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-37835912

RESUMO

To complement previous results, an analysis of the chemical and morphological properties of babassu fibers (Attalea speciosa Mart. ex Spreng.) was conducted in order to evaluate their potential as reinforcements in the production of composites with epoxy matrix. The diameter distribution was analyzed in a sample of one hundred fibers, allowing the verification of its variation. The determination of the chemical properties involved experimental analyses of the constituent index and X-ray diffraction. The diffractogram was used to calculate the crystallinity index and the microfibril angle, which are crucial parameters that indicate the consistency of the mechanical properties of babassu fibers and the feasibility of their use in composites. The results revealed that babassu fiber has a chemical composition, with contents of 28.53% lignin, 32.34% hemicellulose, and 37.97% cellulose. In addition, it showed a high crystallinity index of 81.06% and a microfibril angle of 7.67°. These characteristics, together with previous results, indicate that babassu fibers have favorable chemical and morphological properties to be used as reinforcements in composites, highlighting its potential as an important material for applications in technology areas.

16.
Retin Cases Brief Rep ; 17(4): 438-440, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37364205

RESUMO

PURPOSE: To report a case of acute macular neuroretinopathy (AMN) following SARS-CoV-2 vaccination. METHODS: Case report. RESULTS: An otherwise healthy 28-year-old white woman presented to an ophthalmology department with complaints of black paracentral vision scotomata on both eyes that appeared 2 days after receiving the first dose of Vaxzevria vaccine. Fundus examination revealed bilateral red brown petaloid lesions around the fovea. On spectral domain optical coherence tomography, a hyperreflective plaque between the outer plexiform and outer nuclear layers along with disruption of ellipsoid zone/interdigitation zone was observed. A diagnosis of AMN was made. CONCLUSION: AMN may be an extremely rare adverse event of SARS-COV-2 vaccination, especially in patients with other risk factors. SYNOPSIS: An otherwise healthy 28-year-old white woman was diagnosed with AMN 2 days after SARS-CoV-2 vaccination.


Assuntos
COVID-19 , Macula Lutea , Doenças Retinianas , Síndrome dos Pontos Brancos , Feminino , Humanos , Adulto , Doenças Retinianas/diagnóstico , Doenças Retinianas/etiologia , Doenças Retinianas/patologia , Vacinas contra COVID-19/efeitos adversos , SARS-CoV-2 , Macula Lutea/patologia , COVID-19/prevenção & controle , Tomografia de Coerência Óptica/métodos , Escotoma , Síndrome dos Pontos Brancos/complicações , Doença Aguda , Vacinação/efeitos adversos
17.
Medicina (B Aires) ; 83(1): 52-58, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36774597

RESUMO

OBJECTIVE: To analyze the underlying components of reduced maximal static inspiratory (MIP) and expiratory (MEP) pressures in subjects with Duchenne muscular dystrophy. METHODS: Forty-three subjects were assessed based on routine pulmonary function tests. MIP and MEP were measured the subjects performed maximal expirations and inspirations using a snorkel mouthpiece. Lung volumes were measured using the helium dilution technique. RESULTS: The mean age was 13 years (range, 7-20 years). Median total lung capacity (TLC) and residual volume (RV) were 78.0 (49.0-94.0) and 27.0 (19.7-30.1) of the predicted values respectively. The RV/TLC relationship was 35.3% (28.1-47.7). Thirty-five subjects had a TLC below the lower limit of normal, while 31 had an RV/TLC ratio above the upper limit of normal. The median (IQR) MIP and MEP values were -53.0 (-65.5 to -41.8) and 58.0 (41.5-74.8) cmH2O respectively. MIP and MEP in percent of the predicted values (predicted TLC and RV) were 42.6 (33.3-50.8) and 33.7 (23.9-44.5). MIP in percent of the RV reached for Group A (7-11 years old) was higher (p 0.025) while MEP in percent of the TLC reached for Group B (12-16 years) and C (17-20 years) were higher too (0.031). CONCLUSIONS: In subjects with Duchenne muscular dystrophy, the intrinsic weakness of respiratory muscles and mechanical disadvantage lead to inadequate maximal static pressure generation. Maximal static pressures should be interpreted cautiously as they overestimate respiratory muscle weakness when compared to predicted values obtained at TLC and RV. Our results provide additional data supporting absolute values use rather than predicted values.


OBJETIVO: Analizar los componentes subyacentes de las presiones inspiratorias (MIP) y espiratorias (MEP) estáticas máximas reducidas en sujetos con distrofia de Duchenne (DMD). Métodos: Se evaluaron 43 pacientes mediante pruebas de función pulmonar rutinarias. MIP y MEP fueron medidas a inspiración y espiración máximas. Los volúmenes pulmonares se midieron mediante dilución de helio. RESULTADOS: Edad media 13 años (rango 7-20 años). La capacidad pulmonar total (TLC) y el volumen residual (RV) fueron 78.0% (49.0-94.0) y 27.0% (19.7- 30.1) de los valores predichos. El RV/TLC fue de 35.3% (28.1-47.7). Treinta y cinco sujetos tenían una TLC por debajo del límite inferior de normalidad, 31 tenían una RV/TLC por encima del límite superior de la normalidad. MIP y MEP fueron -53.0 (-65.5 a -41.8) y 58.0 (41.5-74.8) cmH2O, mientras que en % de los predichos (TLC y RV predichos) fueron 42.6 (33.3-50.8) y 33.7 (23.9-44.5). MIP en % del RV alcanzado (Grupo A 7-11 años) fue mayor (p 0.025), y MEP en % de la TLC alcanzada Grupo B (12-16 años) y C (17-20 años), también fue mayor (0.031). CONCLUSIONES: En sujetos con DMD, debilidad intrínseca de los músculos respiratorios y desventaja mecánica conducen a generación de presión estática máxima inadecuada. Las mismas deben interpretarse con cautela, ya que sobrestiman la debilidad de los músculos respiratorios si se las compara con las tablas de valores predichos obtenidos a TLC y RV. Nuestros resultados proporcionan datos adicionales que respaldan la utilización de valores absolutos en lugar de los predichos.


Assuntos
Distrofia Muscular de Duchenne , Humanos , Adolescente , Criança , Distrofia Muscular de Duchenne/complicações , Testes de Função Respiratória , Músculos Respiratórios , Debilidade Muscular/etiologia
18.
Polymers (Basel) ; 15(20)2023 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-37896425

RESUMO

The demand for materials with improved properties and less negative impact on the environment is growing. Artificial stones are examples of these materials produced with up to 90% of particulate material joined by a binder. This article evaluates the physical and mechanical properties of two artificial stones produced with processing steel residue (blast furnace dust waste) and quartz powder. Two binders were used: pure epoxy resin, denoted as ASPB100, or a mixture of 70 wt% epoxy resin with 30 wt% cashew nut shell oil, denoted as ASPB7030. The process took place under vibration, compression (3 MPa/20 min and 90 °C) and vacuum (80 Pa). ASPB100 showed water absorption of 0.07%, while for ASPB7030, it was 0.54%. They were classified as having high mechanical strength associated with bending stress values equal to 32 and 25 MPa, respectively. Stain resistance indicated that both artificial stones had their stains removed with the tested cleaning agents. In this way, the novel artificial stones produced are sustainable alternatives for the application of blast furnace waste and cashew nut shell oil, reducing their negative impacts on the environment.

19.
Materials (Basel) ; 16(21)2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37959467

RESUMO

The influence of parameters involved in the pulsed electric arc, used as an energy source in the tungsten inert gas (TIG)-mediated welding of Duplex UNS S31803 stainless steel, to attend the manufacture of flexible pipes for the extraction of oil and gas is presented. A fundamental part in the manufacturing process of flexible pipelines is the welding of these strips so that corresponding TIG welds will be subjected to the same process and work conditions. Therefore, it is necessary to maintain the same properties in the welded regions. Covering the effects of each parameter of the pulsed electric arc such as peak and base current as welds, cyclic ratio, and pulsation frequency is a desirable endeavor. The final objective is the mitigation of problems that have a great impact on production, such as weld breakage during the conformation of the strip in the process and test failures. With this, tensile, bending, and ferrite percentage tests were performed on 12 samples that qualified as satisfactory in the visual aspect. A minimum tensile strength of 734.57 MPa and a maximum of 775.77 MPa were obtained where all values found are above the tensile strength limit of the base material of 620 MPa. With the completion of the study, it is possible to understand not only the response of the process to each parameter but also the tendency when changing them. Moreover, it is possible to explore the possibility of guiding the changes to achieve results about the visual aspect and the mechanical properties of the welded material.

20.
Polymers (Basel) ; 15(5)2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36904436

RESUMO

Engineering activities aim to satisfy the demands of society. Not only should the economic and technological aspects be considered, but also the socio-environmental impact. In this sense, the development of composites with the incorporation of waste has been highlighted, aiming not only for better and/or cheaper materials, but also optimizing the use of natural resources. To obtain better results using industrial agro waste, we need to treat this waste to incorporate engineered composites and obtain the optimal results for each application desired. The objective of this work is to compare the effect of processing coconut husk particulates on the mechanical and thermal behavior of epoxy matrix composites, since we will need a smooth composite in the near future to be applied by brushes and sprayers with a high quality surface finish. This processing was carried out in a ball mill for 24 h. The matrix was a Bisphenol A diglycidyl ether (DGEBA)/triethylenetetramine (TETA) epoxy system. The tests that were performed were resistance to impact and compression, as well as the linear expansion test. Through this work, it can be observed that the processing of coconut husk powder was beneficial, allowing not only positive improvements to the properties of the composite, but also a better workability and wettability of the particulates, which was attributed to the change in the average size and shape of particulates. That means that the composites with processed coconut husk powders have improved impact strength (46 up to 51%) and compressive strength (88 up to 334%), in comparison with unprocessed particles.

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