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1.
Molecules ; 29(15)2024 Aug 04.
Article in English | MEDLINE | ID: mdl-39125094

ABSTRACT

Adsorptive-photocatalytic composites based on activated carbon (AC) and α-ferrous oxalate dihydrate (α-FOD) were synthesized by an original two-step method and subsequently used for the removal of phenol from aqueous solutions. To obtain the composites, ferrotitaniferous black mineral sands (0.6FeTiO3·0.4Fe2O3) were first dissolved in an oxalic acid solution at ambient pressure, and further treated under hydrothermal conditions to precipitate α-FOD on the AC surface. The ratio of oxalic acid to the mineral sand precursor was tuned to obtain composites with 8.3 and 42.7 wt.% of α-FOD on the AC surface. These materials were characterized by X-ray powder diffraction, scanning electron microscopy, and the nitrogen adsorption-desorption method. The phenol removal efficiency of the composites was determined during 24 h of adsorption under dark conditions, followed by 24 h of adsorption-photocatalysis under visible light irradiation. AC/α-FOD composites with 8.3 and 42.7 wt.% of α-FOD adsorbed 60% and 51% of phenol in 24 h and reached a 90% and 96% removal efficiency after 12 h of irradiation, respectively. Given its higher photocatalytic response, the 42.7 wt.% α-FOD composite was also tested during successive cycles of adsorption and adsorption-photocatalysis. This composite exhibited a reasonable level of cyclability (~99% removal after four alternated dark/irradiated cycles of 24 h and ~68% removal after three simultaneous adsorption-photocatalysis cycles of 24 h). The promising performance of the as-prepared composites opens several opportunities for their application in the effective removal of organic micropollutants from water.

2.
Polymers (Basel) ; 16(13)2024 Jul 04.
Article in English | MEDLINE | ID: mdl-39000767

ABSTRACT

Catalytic biomass pyrolysis is one of the most promising routes for obtaining bio-sustainable products that replace petroleum derivatives. This study evaluates the production of aromatic compounds (benzene, toluene, and xylene (BTX)) from the catalytic pyrolysis of lignocellulosic biomass (Pinus radiata (PR) and Eucalyptus globulus (EG)). Chilean natural zeolite (NZ) was used as a catalyst for pyrolysis reactions, which was modified by double ion exchange (H2NZ) and transition metals impregnation (Cu5H2NZ and Ni5H2NZ). The catalysts were characterized by nitrogen adsorption, X-ray diffraction (XRD), ammonium programmed desorption (TPD-NH3), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). Analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) allowed us to study the influence of natural and modified zeolite catalysts on BTX production. XRD analysis confirmed the presence of metal oxides (CuO and NiO) in the zeolite framework, and SEM-EDS confirmed successful metal impregnation (6.20% for Cu5H2NZ and 6.97% for Ni5H2NZ). Py-GC/MS revealed a reduction in oxygenated compounds such as esters, ketones, and phenols, along with an increase in aromatic compounds in PR from 2.92% w/w (without catalyst) to 20.89% w/w with Ni5H2NZ at a biomass/catalyst ratio of 1/5, and in EG from 2.69% w/w (without catalyst) to 30.53% w/w with Ni5H2NZ at a biomass/catalyst ratio of 1/2.5. These increases can be attributed to acidic sites within the catalyst pores or on their surface, facilitating deoxygenation reactions such as dehydration, decarboxylation, decarbonylation, aldol condensation, and aromatization. Overall, this study demonstrated that the catalytic biomass pyrolysis process using Chilean natural zeolite modified with double ion exchange and impregnated with transition metals (Cu and Ni) could be highly advantageous for achieving significant conversion of oxygenated compounds into hydrocarbons and, consequently, improving the quality of the condensed pyrolysis vapors.

3.
J Hazard Mater ; 476: 135005, 2024 Sep 05.
Article in English | MEDLINE | ID: mdl-38996684

ABSTRACT

Microbially induced carbonate precipitation (MICP) immobilizes toxic metals and reduces their bioavailability in aqueous systems. However, its application in the treatment of acid mine drainage (AMD) is poorly understood. In this study, the genomes of Sporosarcina sp. UB5 and UB10 were sequenced. Urease, carbonic anhydrases, and metal resistance genes were identified and enzymatic assays were performed for their validation. The geochemical mechanism of precipitation in AMD was elucidated through geo-mineralogical analysis. Sporosarcina sp. UB5 was shown to be a new genomospecies, with an average nucleotide identity < 95 % (ANI) and DNA-DNA hybridization < 70 % (DDH) whereas UB10 is close to S. pasteurii. UB5 contained two urease operons, whereas only one was identified in UB10. The ureolytic activities of UB5 and UB10 were 122.67 ± 15.74 and 131.70 ± 14.35 mM NH4+ min-1, respectively. Both strains feature several carbonic anhydrases of the α, ß, or γ families, which catalyzed the precipitation of CaCO3. Only Sporosarcina sp. UB5 was able to immobilize metals and neutralize AMD. Geo-mineralogical analyses revealed that UB5 directly immobilized Fe (1-23 %), Mn (0.65-1.33 %) and Zn (0.8-3 %) in AMD via MICP and indirectly through adsorption to calcite and binding to bacterial cell walls. The MICP-treated AMD exhibited high removal rates (>67 %) for Ag, Al, As, Ca, Cd, Co, Cu, Fe, Mn, Pb, and Zn, and a removal rate of 15 % for Mg. This study provides new insights into the MICP process and its applications to AMD treatment using autochthonous strains.


Subject(s)
Mining , Sporosarcina , Urease , Sporosarcina/genetics , Sporosarcina/metabolism , Urease/metabolism , Chemical Precipitation , Carbonates/chemistry , Carbonic Anhydrases/metabolism , Carbonic Anhydrases/genetics , Water Pollutants, Chemical/metabolism , Water Pollutants, Chemical/chemistry
4.
Molecules ; 29(12)2024 Jun 19.
Article in English | MEDLINE | ID: mdl-38930987

ABSTRACT

Peanut shells' adsorption performance in caffeine and triclosan removal was studied. Peanut shells were analyzed for their chemical composition, morphology, and surface functional groups. Batch adsorption and fixed-bed column experiments were carried out with solutions containing 30 mg/L of caffeine and triclosan. The parameters examined included peanut shell particle size (120-150, 300-600, and 800-2000 µm), adsorbent dose (0.02-60 g/L), contact time (up to 180 min), bed height (4-8 cm), and hydraulic loading rate (2.0 and 4.0 m3/m2-day). After determining the optimal adsorption conditions, kinetics, isotherm, and breakthrough curve models were applied to analyze the experimental data. Peanut shells showed an irregular surface and consisted mainly of polysaccharides (around 70% lignin, cellulose, and hemicellulose), with a specific surface area of 1.7 m2/g and a pore volume of 0.005 cm3/g. The highest removal efficiencies for caffeine (85.6 ± 1.4%) and triclosan (89.3 ± 1.5%) were achieved using the smallest particles and 10.0 and 0.1 g/L doses over 180 and 45 min, respectively. Triclosan showed easier removal compared to caffeine due to its higher lipophilic character. The pseudo-second-order kinetics model provided the best fit with the experimental data, suggesting a chemisorption process between caffeine/triclosan and the adsorbent. Equilibrium data were well-described by the Sips model, with maximum adsorption capacities of 3.3 mg/g and 289.3 mg/g for caffeine and triclosan, respectively. In fixed-bed column adsorption tests, particle size significantly influenced efficiency and hydraulic behavior, with 120-150 µm particles exhibiting the highest adsorption capacity for caffeine (0.72 mg/g) and triclosan (143.44 mg/g), albeit with clogging issues. The experimental data also showed good agreement with the Bohart-Adams, Thomas, and Yoon-Nelson models. Therefore, the findings of this study highlight not only the effective capability of peanut shells to remove caffeine and triclosan but also their versatility as a promising option for water treatment and sanitation applications in different contexts.


Subject(s)
Arachis , Caffeine , Triclosan , Caffeine/chemistry , Caffeine/isolation & purification , Triclosan/chemistry , Triclosan/isolation & purification , Arachis/chemistry , Adsorption , Kinetics , Water Pollutants, Chemical/chemistry , Water Pollutants, Chemical/isolation & purification , Particle Size , Water Purification/methods
5.
Nutrients ; 16(10)2024 May 20.
Article in English | MEDLINE | ID: mdl-38794777

ABSTRACT

Eating disorders (EDs) manifest as persistent disruptions in eating habits or related behaviors, significantly impacting physical health and psychosocial well-being. Nutritional assessment in ED patients is crucial for monitoring treatment efficacy. While dual-energy X-ray absorptiometry (DEXA) remains standard, interest in alternative methods such as bioelectrical impedance vector analysis (BIVA) and Nutritional Ultrasound® (NU) has risen due to their affordability and portability. Additionally, hand dynamometry offers a user-friendly approach to assessing grip strength (HGS), indicative of nutritional status. A prospective study was carried out to evaluate the utility of BIVA, NU®, and HGS in 43 female AN patients. Measurements were taken at baseline and hospital discharge. A total of 41 patients completed the study. After the intervention, numerous BIVA-related parameters such as fat (3.5 ± 2 kg vs. 5.3 ± 2.7 kg, p < 0.001) and free fat mass (33.9 ± 3.8 kg vs. 37.5 ± 4.1 kg, p < 0.001) were partially restored. Similarly, Nutritional Ultrasound® showed promising results in assessing body composition changes such as total abdominal fat tissue (0.5 ± 0.3 cm vs. 0.9 ± 0.3 cm, p < 0.05). In the same way, rectus femoris cross-sectional area values correlated with clinical outcomes such as free fat mass (0.883, p < 0.05) and appendicular muscle mass (0.965, p < 0.001). HGS reached the normality percentile after the intervention (21.6 ± 9.1 kg vs. 25.9 ± 12.3 kg, p < 0.05), demonstrating a significant association between grip strength and body composition parameters such as free fat mass (0.658, p < 0.001) and appendicular muscle mass (0.482, p < 0.001). Incorporating BIVA-, NU®-, and HGS-enhanced nutritional assessment into the treatment of AN patients offers cost-effective, portable, and non-invasive alternatives to DEXA. These techniques offer valuable insights into changes in body composition and nutritional status, which, in turn, facilitate treatment monitoring and contribute to improved patient outcomes.


Subject(s)
Anorexia Nervosa , Body Composition , Electric Impedance , Hand Strength , Nutrition Assessment , Nutritional Status , Ultrasonography , Humans , Female , Pilot Projects , Ultrasonography/methods , Prospective Studies , Anorexia Nervosa/physiopathology , Anorexia Nervosa/therapy , Adult , Young Adult , Adolescent , Recovery of Function
6.
Curr Microbiol ; 81(2): 62, 2024 Jan 12.
Article in English | MEDLINE | ID: mdl-38216774

ABSTRACT

Microbial contamination of coffee beans arises from various factors such as harvesting, handling, and storage practices, during which ochratoxin A (OTA)-producing fungi develop and proliferate. The presence of elevated concentrations of OTA poses a serious health risk to coffee consumers. Therefore, the implementation of a post-harvest treatment involving the use of bacteria known to antagonize OTA-producing fungi constitutes a safe alternative for reducing or eliminating the toxin's concentration in coffee beans. In this study, coffee beans (Coffea arabica L.) were inoculated with Bacillus licheniformis M2-7, after which we monitored fungal growth, in vitro antagonism, and OTA concentration. Our findings demonstrated that coffee beans inoculated with this bacterial strain exhibited a significant decrease in fungal populations belonging to the genera Aspergillus and Penicillium, which are known to produce OTA. Moreover, strain M2-7 decreased the growth rates of these fungi from 67.8% to 95.5% (P < 0.05). Similarly, inoculation with B. licheniformis strain M2-7 effectively reduced the OTA concentration from 24.35 ± 1.61 to 5.52 ± 1.69 µg/kg (P < 0.05) in stored coffee beans. These findings suggest that B. licheniformis M2-7 holds promise as a potential post-harvest treatment for coffee beans in storage, as it effectively inhibits the proliferation of OTA-producing fungi and lowers the toxin's concentration.


Subject(s)
Bacillus licheniformis , Coffea , Ochratoxins , Food Contamination/analysis , Coffea/microbiology
7.
Data Brief ; 52: 109969, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38152491

ABSTRACT

This article presents a set of experimental data on the mechanical and physical properties of the Ecuadorian endemic bamboo species Guadua angustifolia kunth (Guadua a.k.), specifically the "Caña Mansa" biotype. The data on compressive, shear, tensile and bending strength, as well as the moisture content and density, were obtained by carrying out the corresponding tests following the ISO 22157:2019 standard. For this purpose, each bamboo culm examined was divided along its height into three sections that were thoroughly characterized. The equations used for the calculations of the mechanical and physical properties are described in detail for each test. Besides, the main mechanical properties of the characterized bamboo were compared to those of similar species reported in the literature. Property charts (compressive/tensile strength and modulus of rupture vs. density) were built to compare the Ecuadorian biotype evaluated with other classical and green materials by using appropriate software. These data give an insight into the valorization of natural structural materials harvested in the Americas for potential applications in different engineering fields, particularly for sustainable building.

8.
Polymers (Basel) ; 15(18)2023 Sep 17.
Article in English | MEDLINE | ID: mdl-37765644

ABSTRACT

Pinus radiata (PR) and Eucalyptus globulus (EG) are the most planted species in Chile. This research aims to evaluate the pyrolysis behaviour of PR and EG from the Bío Bío region in Chile. Biomass samples were subjected to microwave pretreatment considering power (259, 462, 595, and 700 W) and time (1, 2, 3, and 5 min). The maximum temperature reached was 147.69 °C for PR and 130.71 °C for EG in the 700 W-5 min condition, which caused the rearrangement of the cellulose crystalline chains through vibration and an increase in the internal energy of the biomass and the decomposition of lignin due to reaching its glass transition temperature. Thermogravimetric analysis revealed an activation energy (Ea) reduction from 201.71 to 174.91 kJ·mol-1 in PR and from 174.80 to 158.51 kJ·mol-1 in EG, compared to the untreated condition (WOT) for the 700 W-5 min condition, which indicates that microwave pretreatment improves the activity of the components and the decomposition of structural compounds for subsequent pyrolysis. Functional groups were identified by Fourier transform infrared spectroscopy (FTIR). A decrease in oxygenated compounds such as acids (from 21.97 to 17.34% w·w-1 and from 27.72 to 24.13% w·w-1) and phenols (from 34.41 to 31.95% w·w-1 and from 21.73 to 20.24% w·w-1) in PR and EG, respectively, was observed in comparison to the WOT for the 700 W-5 min condition, after analytical pyrolysis. Such results demonstrate the positive influence of the pretreatment on the reduction in oxygenated compounds obtained from biomass pyrolysis.

9.
Polymers (Basel) ; 15(5)2023 Feb 23.
Article in English | MEDLINE | ID: mdl-36904362

ABSTRACT

The study of new materials formulated using recycled polymers offers an ecological and sustainable alternative for the construction industry. In this work, we optimized the mechanical behavior of manufactured masonry veneers made from concrete reinforced with recycled polyethylene terephthalate (PET) from discarded plastic bottles. For this purpose, we used the response surface methodology to evaluate the compression and flexural properties. PET percentage, PET size and aggregate size were used as input factors in a Box-Behnken experimental design resulting in a total of 90 tests. The fraction of the commonly used aggregates replaced by PET particles was 15%, 20% and 25%. The nominal size of the PET particles used was 6, 8 and 14 mm, while the size of the aggregates was 3, 8 and 11 mm. The function of desirability was used to optimize response factorials. The globally optimized formulation contained 15% of 14 mm PET particles in the mixture, and 7.36 mm aggregates, obtaining important mechanical properties of this characterization of masonry veneers. The flexural strength (four-point) was 1.48 MPa, and the compression strength was 3.96 MPa; these values show property improvements of 110% and 94%, respectively, compared to commercial masonry veneers. Overall, this offers the construction industry a robust and environmentally friendly alternative.

10.
Front Plant Sci ; 13: 1012859, 2022.
Article in English | MEDLINE | ID: mdl-36275540

ABSTRACT

Climate warming may affect the performance of plants directly through altering vegetative or reproductive traits, and indirectly through modifying interactions with their pollinators. On the other hand, the addition of fertilizers to the soil may increase the quantity and quality of floral rewards, favoring the visitation of pollinators and, consequently, the reproductive success of plants. However, it is still unknown whether fertilizers may counteract the effects of increased temperature on the vegetative, floral, and reproductive traits of plants, as well as on the interaction with their pollinators. The aim of this study is to evaluate the effects of the input of organic and synthetic fertilizers on several vegetative and floral traits, and on the rate of legitimate floral visitors and reproductive success of the squash during two seasons, under a scenario of an increase in ambient temperature. During the dry and the rainy seasons, three vegetative, eleven floral, and two reproductive traits, as well as the duration of visits and visitation rate of legitimate floral visitors were evaluated in squash plants distributed into six treatments in a bifactorial design: temperature (ambient or elevated temperature) and fertilizer (organic, synthetic or without supplementary fertilizers). Contrary to our predictions, we found that an increase of ~1.5°C in ambient temperature, positively influenced several vegetative, floral, and reproductive traits in this crop, and that organic fertilizers, in general, was not better than synthetic fertilizers in improving those traits. Interestingly, the response of the squash and indirectly on their legitimate floral visitors to the increase of temperature and the input of fertilizers vary widely among seasons, suggesting great temporal variation in plant-pollinator responses to temperature and nutrient availability, which makes food security more unpredictable.

11.
ACS Omega ; 7(24): 20457-20476, 2022 Jun 21.
Article in English | MEDLINE | ID: mdl-35935292

ABSTRACT

The development of sustainable, cost-efficient, and high-performance nanofluids is one of the current research topics within drilling applications. The inclusion of tailorable nanoparticles offers the possibility of formulating water-based fluids with enhanced properties, providing unprecedented opportunities in the energy, oil, gas, water, or infrastructure industries. In this work, the most recent and relevant findings related with the development of customizable nanofluids are discussed, focusing on those based on the incorporation of 2D (two-dimensional) nanoparticles and environmentally friendly precursors. The advantages and drawbacks of using 2D layered nanomaterials including but not limited to silicon nano-glass flakes, graphene, MoS2, disk-shaped Laponite nanoparticles, layered magnesium aluminum silicate nanoparticles, and nanolayered organo-montmorillonite are presented. The current formulation approaches are listed, as well as their physicochemical characterization: rheology, viscoelastic properties, and filtration properties (fluid losses). The most influential factors affecting the drilling fluid performance, such as the pH, temperature, ionic strength interaction, and pressure, are also debated. Finally, an overview about the simulation at the microscale of fluids flux in porous media is presented, aiming to illustrate the approaches that could be taken to supplement the experimental efforts to research the performance of drilling muds. The information discussed shows that the addition of 2D nanolayered structures to drilling fluids promotes a substantial improvement in the rheological, viscoelastic, and filtration properties, additionally contributing to cuttings removal, and wellbore stability and strengthening. This also offers a unique opportunity to modulate and improve the thermal and lubrication properties of the fluids, which is highly appealing during drilling operations.

12.
Materials (Basel) ; 15(3)2022 Jan 19.
Article in English | MEDLINE | ID: mdl-35160674

ABSTRACT

Magnetic composites obtained by impregnation of lignocellulosic biomass with magnetite nanoparticles were used for zinc(II) removal from aqueous synthetic solutions. Laurel, canelo and eucalyptus sawdust, with a particle size between 74 and 150 µm were used as support. Structural and morphological examinations of the composites confirmed the presence of magnetite nanoparticles in the lignocellulosic support. Transmission Electron Microscopy showed nanoparticles with diameters of about 20 nm. The maximum removal efficiencies for 7 g L-1 of modified adsorbent were increased to 98.9, 98.8 and 97.6% for laurel, canelo and eucalyptus magnetic composites, respectively, in comparison to 60.9, 46.0 and 33.3%, for corresponding unmodified adsorbents. Adsorption data was analyzed using pseudo-first, pseudo-second order and intra-particle diffusion kinetic models and various isotherm models. The results determined that Freundlich isotherm fits the Zn ions adsorption on magnetite modified adsorbents while chemisorption and boundary diffusion were dominating the process.

13.
Curr Opin Chem Biol ; 66: 102098, 2022 02.
Article in English | MEDLINE | ID: mdl-34768088

ABSTRACT

The cellular prion protein (PrPC) is a metal-binding biomolecule that can interact with different protein partners involved in pivotal physiological processes, such as neurogenesis and neuronal plasticity. Recent studies profile copper and PrPC as important players in the pathological mechanisms of Alzheimer's disease and cancer. Although the copper-PrPC interaction has been characterized extensively, the role of the metal ion in the physiological and pathological roles of PrPC has been barely explored. In this article, we discuss how copper binding and proteolytic processing may impact the ability of PrPC to recruit protein partners for its functional roles. The importance to dissect the role of copper-PrPC interactions in health and disease is also underscored.


Subject(s)
Alzheimer Disease , Neoplasms , Chemistry, Bioinorganic , Copper/metabolism , Humans , Prion Proteins/chemistry
14.
Genus ; 77(1): 30, 2021.
Article in English | MEDLINE | ID: mdl-34744175

ABSTRACT

In this paper, we measure the effect of the 2020 COVID-19 pandemic wave at the national and subnational levels in selected Latin American countries that were most affected: Brazil, Chile, Ecuador, Guatemala, Mexico, and Peru. We used publicly available monthly mortality data to measure the impacts of the pandemic using excess mortality for each country and its regions. We compare the mortality, at national and regional levels, in 2020 to the mortality levels of recent trends and provide estimates of the impact of mortality on life expectancy at birth. Our findings indicate that from April 2020 on, mortality exceeded its usual monthly levels in multiple areas of each country. In Mexico and Peru, excess mortality was spreading through many areas by the end of the second half of 2020. To a lesser extent, we observed a similar pattern in Brazil, Chile, and Ecuador. We also found that as the pandemic progressed, excess mortality became more visible in areas with poorer socioeconomic and sanitary conditions. This excess mortality has reduced life expectancy across these countries by 2-10 years. Despite the lack of reliable information on COVID-19 mortality, excess mortality is a useful indicator for measuring the effects of the coronavirus pandemic, especially in the context of Latin American countries, where there is still a lack of good information on causes of death in their vital registration systems. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41118-021-00139-1.

15.
Can Stud Popul ; 48(2-3): 165-200, 2021.
Article in English | MEDLINE | ID: mdl-34667369

ABSTRACT

The new coronavirus (COVID-19) is having a major impact on mortality and survival in most countries of the world, with Mexico being one of the countries most heavily impacted by the pandemic. In this paper, we study the impact of COVID-19 deaths on period life expectancy at birth in Mexico by sex and state. We focus on the loss of life expectancy at different ages as a geographically comparable measure of the pandemic's impact on the population in 2020. Results show that males have been affected more than women since they have lost more years of life expectancy at birth due to COVID-19, and they have also experienced a high variation of life expectancy loss across states. The biggest life expectancy loss concentrates in the Northeastern, Central, and Southeastern (Yucatan peninsula) states. Considering the likely undercount associated with COVID-19 deaths, sensitivity analysis suggests that the new coronavirus is having a much larger impact on life expectancy in Mexico than the official government data appears to indicate. Continuos assessment of the pandemic will help state governments quantify the effect of current and new public health measures.


La nouvelle maladie à coronavirus (COVID-19) a un impact majeur sur la mortalité et la survie dans la plupart des pays du monde, le Mexique étant parmi les pays les plus fortement touchés par la pandémie. Dans cet article, nous étudions l'impact des décès dus à la COVID-19 sur l'espérance de vie à la naissance comme mesure géographiquement comparable de l'impact de la pandémie sur la population en 2020. Les résultats montrent que les hommes ont été plus touchés que les femmes, ils ont perdu plus d'années d'espérance de vie à la naissance en raison de la COVID-19 et ont également connu une forte variation de la perte d'espérance de vie entre les États mexicains. La plus grande perte d'espérance de vie est concentrée dans les États du nord-est, du centre et du sud-est (péninsule du Yucatan). L'analyse de sensibilité tient compte du sous-dénombrement probable associé aux décès dus à la COVID-19 et suggère que la maladie a un impact beaucoup plus important sur l'espérance de vie au Mexique que les données officielles du gouvernement ne semblent l'indiquer. Une évaluation continue de la pandémie aidera les gouvernements des États à quantifier l'effet des mesures de santé publique actuelles et nouvelles à mesure que la pandémie se poursuit.

16.
Phys Chem Chem Phys ; 23(40): 22923-22935, 2021 Oct 20.
Article in English | MEDLINE | ID: mdl-34617940

ABSTRACT

The performance of fibrous membrane composites fabricated via electrospinning is strongly influenced by the solution's properties, process variables and ambient conditions, although a precise mechanism for controlling the properties of the resulting composite has remained elusive. In this work, we focus on the fabrication of electrospun poly(vinylpyrrolidone) (PVP) fibers, by varying both the polymer concentration and the mixture of ethanol (EtOH) and dimethylformamide (DMF) used as solvent. The impact of the solvent composition on the structural properties is assessed by a combined experimental and theoretical approach, employing scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheology, Fourier-transform infrared spectroscopy (FTIR) and stress-strain curves obtained from tensile tests to characterize the fibrous membranes produced, and density functional theory (DFT) calculations to explain the solvent's affect on PVP crystallization. We establish a morphological phase diagram, and propose a possible mechanism based on the measured fiber diameter distribution, the viscoelastic properties of the precursor solution, the correlation between the functional groups and the mechanical properties, the thermal transitions and the degree of crystallinity. We also employ DFT calculations to model the polymer coverage at equilibrium of a PVP polymer chain in the presence of EtOH/DMF solvent mixtures to corroborate the crucial role their O or -OH groups play in achieving high PVP coverages and promoting the stability of the resulting fiber. These findings will be valuable to researchers interested in predicting, modulating, and controlling both a fiber's morphology and its concomitant physico-chemical properties.

17.
J Environ Manage ; 300: 113737, 2021 Dec 15.
Article in English | MEDLINE | ID: mdl-34536739

ABSTRACT

Persistent Organic Pollutants (POPs) have become a very serious issue for the environment because of their toxicity, resistance to conventional degradation mechanisms, and capacity to bioconcentrate, bioaccumulate and biomagnify. In this review article, the safety, regulatory, and remediation aspects of POPs including aromatic, chlorinated, pesticides, brominated, and fluorinated compounds, are discussed. Industrial and agricultural activities are identified as the main sources of these harmful chemicals, which are released to air, soil and water, impacting on social and economic development of society at a global scale. The main types of POPs are presented, illustrating their effects on wildlife and human beings, as well as the ways in which they contaminate the food chain. Some of the most promising and innovative technologies developed for the removal of POPs from water are discussed, contrasting their advantages and disadvantages with those of more conventional treatment processes. The promising methods presented in this work include bioremediation, advanced oxidation, ionizing radiation, and nanotechnology. Finally, some alternatives to define more efficient approaches to overcome the impacts that POPs cause in the hydric sources are pointed out. These alternatives include the formulation of policies, regulations and custom-made legislation for controlling the use of these pollutants.


Subject(s)
Environmental Pollutants , Pesticides , Food Chain , Humans , Persistent Organic Pollutants , Pesticides/analysis , Soil
18.
Sci Total Environ ; 801: 149666, 2021 Dec 20.
Article in English | MEDLINE | ID: mdl-34428664

ABSTRACT

The caffeine adsorptive performance and compatibility characteristics (Eisenia foetida Savigny) of rice husk, peanut shell, corn cob and coconut fiber were studied, aiming to assess the suitability of these residues for vermifilter beds. For this purpose, the agro-industrial residues were characterized and the E. foetida Savigny compatibility was determined by acute and chronic toxicity tests. Batch adsorption tests were performed using caffeine solutions. Optimal adsorption conditions, kinetic models, isotherm type and the influence of three particle sizes (120-150, 300-600, 800-2000 µm) in the caffeine removal were determined. Coconut fiber (120-150 µm) proved to be the most efficient residue for the caffeine removal (94.2%), requiring 4 g/L for 30 min. However, coconut fiber was the less compatible for earthworms (14d-LC50 = 82%). The results obtained allow to define adequate strategies, such as mixing highly adsorptive residues with the more compatible ones, to choose the most effective materials for vermifiltration technologies.


Subject(s)
Oligochaeta , Adsorption , Animals , Caffeine , Cocos , Kinetics
19.
Materials (Basel) ; 14(9)2021 Apr 22.
Article in English | MEDLINE | ID: mdl-33922287

ABSTRACT

Contamination of water by heavy metals is a major environmental concern due to the potential ecological impact on human health and aquatic ecosystems. In this work, we studied the chemical modification of various fruit peels such as banana (BP), granadilla (GP), and orange ones (OP) in order to obtain novel bio-adsorbents to improve the removal of Zn(II) ions from 50 mg·L-1 synthetic aqueous solutions. For this purpose, sodium hydroxide and calcium acetate were employed to modify the fruit peels. The moisture, extractives, lignin, hemicellulose, and cellulose contents of the raw materials were determined according to ASTM standards. The obtained bio-adsorbents were characterized by scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). The results showed the OP bio-adsorbents performed better, especially when the concentration of the modifier solutions increased, e.g., the OP particles modified using 0.8 M NaOH and Ca(CH3COO)2 solutions resulted in 97% removal of Zn(II) contaminating ions and reached a maximum adsorption capacity of 27.5 mg Zn per gram of bio-adsorbent. The adsorption processes were found to follow a pseudo-second order model. The error function sum of square error indicated the Freundlich isotherm (non-linear regression) as best fit model. The obtained results are particularly interesting for material selection in wastewater treatment technologies based on contaminant adsorption.

20.
Rev Chil Anest ; 50(4): 609-612, 2021. ilus
Article in Spanish | LILACS | ID: biblio-1526325

ABSTRACT

Erector spinae plane block (ESP) is a regional anesthesia technique consisting of blocking the interfascial plane, where local anesthetic (LA) is injected at the site where the dorsal branch of the spinal nerve emerges. There are various publications on the application of the block (EPS) in the adult population, however there are few reports of the use of this block in pediatric surgery. We present the first case report of an infant under 9 months of age with the presence of a tumor in the anterior mediastinum, who underwent a resection through the 6th intercostal space, previous blockage of the erector spinae under ultrasound vision. The patient did not present adverse effects and was discharged on the fourth postoperative day.


El bloqueo del plano erector de la espina (ESP) es una técnica de anestesia regional consistente en bloquear el plano interfascial, donde se inyecta anestésico local (LA) en el sitio donde emerge la rama dorsal del nervio espinal. Existen diversas publicaciones sobre la aplicación del bloqueo (EPS) en población adulta, sin embargo, hay pocos reportes del uso de este bloqueo en cirugía pediátrica. Presentamos el primer reporte de caso de una lactante menor de 9 meses de edad con presencia de tumor en mediastino anterior, al cual se le hizo una resección a través del 6° espacio intercostal, previo bloqueo del erector de la espina bajo visión ecográfica. La paciente no presentó efectos adversos y fue dada de alta al cuarto día posoperatorio.


Subject(s)
Humans , Female , Infant , Thoracotomy/methods , Paraspinal Muscles , Anesthetics, Local/administration & dosage , Nerve Block/methods , Mediastinal Neoplasms/surgery
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