16 research outputs found

    Respiratory viruses detected in Mexican children younger than 5 years old with community-acquired pneumonia: a national multicenter study

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    Background: Acute respiratory infections are the leading cause of mortality in children worldwide, especially in developing countries. Pneumonia accounts for 16% of all deaths of children under 5 years of age and was the cause of death of 935 000 children in 2015. Despite its frequency and severity, information regarding its etiology is limited. The aim of this study was to identify respiratory viruses associated with community-acquired pneumonia (CAP) in children younger than 5 years old. Methods: One thousand four hundred and four children younger than 5 years of age with a clinical and/or radiological diagnosis of CAP in 11 hospitals in Mexico were included. Nasal washes were collected, placed in viral medium, and frozen at �70 C until processing. The first 832 samples were processed using the multiplex Bio-Plex/Luminex system and the remaining 572 samples using the Anyplex multiplex RT-PCR. Clinical data regarding diagnosis, clinical signs and symptoms, radiographic pattern, and risk factors were obtained and recorded. Results: Of the samples tested, 81.6% were positive for viruses. Respiratory syncytial virus (types A and B) was found in 23.7%, human enterovirus/rhinovirus in 16.6%, metapneumovirus in 5.7%, parainfluenza virus (types 1–4) in 5.5%, influenza virus (types A and B) in 3.6%, adenovirus in 2.2%, coronavirus (NL63, OC43, 229E, and HKU1) in 2.2%, and bocavirus in 0.4%. Co-infection with two or more viruses was present in 22.1%; 18.4% of the samples were negative. Using biomass for cooking, daycare attendance, absence of breastfeeding, and co-infections were found to be statistically significant risk factors for the presence of severe pneumonia. Conclusions: Respiratory syncytial virus (types A and B), human enterovirus/rhinovirus, and metapneumovirus were the respiratory viruses identified most frequently in children younger than 5 years old with CAP. Co-infection was present in an important proportion of the children

    Chitosan–Starch–Keratin composites: Improving thermo-mechanical and degradation properties through chemical modification

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    The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresChitosan–starch polymers are reinforced with different keratin materials obtained from chicken feather. Keratin materials are treated with sodium hydroxide; the modified surfaces are rougher in comparison with untreated surfaces, observed by Scanning Electron Microscopy. The results obtained by Differential Scanning Calorimetry show an increase in the endothermic peak related to water evaporation of the films from 92 °C (matrix) up to 102–114 °C (reinforced composites). Glass transition temperature increases from 126 °C in the polymer matrix up to 170–200 °C for the composites. Additionally, the storage modulus in the composites is enhanced up to 1614 % for the composites with modified ground quill, 2522 % for composites with modified long fiber and 3206 % for the composites with modified short fiber. The lysozyme test shows an improved in the degradability rate, the weight loss of the films at 21 days is reduced from 73 % for chitosan-starch matrix up to 16 % for the composites with 5wt% of quill; but all films show a biodegradable character depending on keratin type and chemical modification. The outstanding properties related to the addition of treated keratin materials show that these natural composites are a remarkable alternative to potentiat-ing chitosan–starch films with sustainable featuresUniversidad Autónoma del Estado de México Tecnológico Nacional de México, Instituto Tecnológico de Querétaro Universidad Nacional Autónoma de México Tecnológico Nacional de México, Instituto Tecnológico de Celaya Universidad Autónoma de Cd. Juáre

    Improvements in the thermomechanical and electrical behavior of hybrid carbon-epoxy nanocomposites

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    In this work, polymeric composites of epoxy matrix reinforced with 1D and 2D nanocarbon allotropes are reported. Hybrid 3D nanostructures formed from 1D multi-walled carbon nanotubes and 2D graphene derivatives improve the electrical and thermomechanical response of the synthesized nanocomposites. Additionally, oxygenated moieties in the surface of the sp2 carbon allotropes positively influences the dispersion of nanomaterials in the matrix and promote better interfaces among the polymeric matrix and reinforcements. Raman spectroscopy detects the different interactions of polymeric chains with carbon nanomaterials in different loads. Furthermore, Raman mapping shows the carbon dispersion regions and the influence on the final mechanical properties of the materials. The viscoelastic response evaluated by Dynamical Mechanical Analysis shows improvements of up to 138% in the storage modulus of nanocomposites with oxidized nanostructures in comparison to neat epoxy. 3D nanostructures changed the insulating nature of epoxy when the carbon nanomaterials formed the interconnected network. Some nanocomposites show an abrupt change from the insulator epoxy resin toward a semiconductor response, mainly in hybrids reinforced with pristine multi-walled carbon nanotubes and reduced graphene oxide. The TEM images of the nanocomposites showed interconnections between the 1D-2D hybrid carbon nanomaterials, which suggest a synergetic effec

    Microbiological and physicochemical properties of meat coated with microencapsulated Mexican oregano (Lippia graveolens Kunth) and basil (Ocimum basilicum L.) essential oils mixture

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    Microencapsulated essential oils (EOs) are increasingly used to protect the safety of foods due to their natural origin. The aim of this work was to determine the chemical composition of Mexican oregano (Lippia graveolens Kunth) (MOEO) and basil (Ocimum basilicum L.) (BEO) EOs, their combined effect against E. coli O157:H7, Lactobacillus plantarum, Brochothrix thermosphacta and Pseudomonas fragi, and their effect on microbiological and physicochemical properties of coated pork meat. EOs chemical composition was determined by GC/MS, their microencapsulated mixture (4 mg MOEO/mL/11 mg BEO/mL) was added to a filmogenic dispersion. Fluorescent probes were used to study the antimicrobial filmogenic active dispersion (FD) effect. Pork meat pieces were coated without microencapsulated EOs (CC), using FD (AC), or uncoated (C), vacuum packed and stored 28 days at 4 °C. Thymol (28.9%) and linalool (23.7%) were the major components of MOEO and BEO, respectively. The cell membrane of all bacteria was damaged by contact with FD. FD-coated samples (AC) exhibited the lowest concentration of 2-thiobarbituric acid reacting substances (TBARS) (0.027 ± 0.001 mg malonaldehyde/kg meat) and natural microbiota growth, while odor and color were the most accepted by untrained judges (range > 6). Coatings added with microencapsulated EOs mixture are a natural food preservation alternative to increase the shelf life of refrigerated meat products

    Effect of transglutaminase cross-linking in protein isolates from a mixture of Two Quinoa varieties with chitosan on the physicochemical properties of edible films

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    The growing demand forminimally processed foodswith a long shelf life and environmentally friendly materials has forced industry to develop new technologies for food preservation and handling. The use of edible films has emerged as an alternative solution to this problem, and mixtures of carbohydrates and proteins, may be formulated to improve their properties. The objective of this work was to evaluate the effect of protein cross-linking with transglutaminase (TG) of two varieties of quinoa protein isolate (Chenopodium quinoa) [Willd (QW), and Pasankalla (QP)] on the physicochemical and barrier properties of edible films based on chitosan (CT)-quinoa protein. The evaluated properties were water vapor permeability (WVP), solubility, adsorption, roughness determined by atomic force microscopy, and the interactions among the main film components determined by Raman spectroscopy. The results indicated that TG interacted with lysine of QW and QP. CT:QW (1:5, w/w) showed the lowest solubility (14.02 ± 2.17% w/w). WVP varied with the composition of the mixture. The WVP of CT:quinoa protein ranged from 2.85 to 9.95 × 10-11 g cm Pa-1 cm-2 s-1 without TG, whereas adding TG reduced this range to 2.42-4.69 × 10-11 g cm Pa-1 cm-2 s-1. The addition of TG to CT:QP (1:10, w/w) reduced the film surface roughness from 8.0 ± 0.5 nm to 4.4 ± 0.3 nm. According to the sorption isotherm, the addition of TG to CT-QW films improved their stability [monolayer (Xm) = 0.13 ± 0.02 %]. Films with a higher amount of cross-linking showed the highest improvement in the evaluated physical properties, but interactions among proteins that were catalyzed by TG depended on the protein source and profile
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