Influence of urea on methyl β -D-glucopyranoside in alkali at different temperatures

The dissolution efficiency plays an important role on the properties of regenerated cellulose-based products. Urea is known to be one of the additives aiding to improve cellulose dissolution in the NaOH(aq) system. The acting mechanism caused by urea has been debated and one of the hypothesis is that urea could induce a conformational change on cellulose, which promotes dissolution. Here we used NMR spectroscopy on a model system for cellulose, namely, methyl β -D-glucopyranoside (β -MeO-Glcp) and compared chemical shifts and J couplings, which both are indicators for conformational changes, as a function of temperature and upon the addition of urea. We found that in NaOH(aq), the hydroxymethyl group changes its conformation in favour of the population of the gt rotamer, while the presence of urea induced temperature dependent conformational changes. Heteronuclear Overhauser effect experiments showed that urea associates with cellulose but in a non-specific manner. This suggests that urea rather than binding to the carbohydrate, changes the chemical environment inducing a change in conformation of β -MeO-Glcp and likely also for cellulose when dissolved in NaOH(aq) with urea

A 3D printed photoreactor for investigating variable reaction geometry, wavelength, and fluid flow

Research in the field of photochemistry, including photocatalysis and photoelectrocatalysis, has been revitalized due to the potential that photochemical reactions show in the sustainable production of chemicals. Therefore, there is a need for flexible photoreactor equipment that allows for the evaluation of the geometry, light wavelength, and intensity of the vessel, along with the fluid flow in various photochemical reactions. Light emitting diodes (LEDs) have narrow emission spectra and can be either pulsed or run continuously; being flexible, they can be arranged to fit the dimensions of various types of the reactor vessel, depending on the application. This study presents a 3D printed photoreactor with the ability to adjust distances easily and switch between high-power LED light sources. The reactor design utilizes customized printed circuit boards to mount varying numbers and types of LEDs, which enables multiple wavelengths to be used simultaneously. These LED modules, comprised of heat sinks and cooling fans, fulfill the higher heat dissipation requirements of high-power LEDs. The flexibility of the reactor design is useful for optimizing the reaction geometry, flow conditions, wavelength, and intensity of photochemical reactions on a small scale. The estimates for incident light intensity under five possible reactor configurations using ferrioxalate actinometry are reported so that comparisons with other photoreactors can be made. The performance of the photoreactor for differing vessel sizes and distances, in both the flow and batch modes, is given for a photochemical reaction on 2-benzyloxyphenol-a model substance for lignin and applicable in the production of biobased chemicals

Aqueous N,N-dimethylmorpholinium hydroxide as a novel solvent for cellulose

N,N-dimethylmorpholinium hydroxide was synthesized and its ability to dissolve microcrystalline cellulose and pulp was assessed for the first time. Microscopy and UV–Vis measurements showed that dissolution occurred over a range of 1–2\ua0M concentration of the solvent and a maximum solubility of 7\ua0wt% microcrystalline cellulose could be achieved. The stability of cellulose solutions was evaluated by size exclusion chromatography, which did not detect degradation to any noticeable extent. This observation was further confirmed by\ua013C NMR measurements. Finally, DLS studies confirmed that most of the cellulose was molecularly dissolved, with intrinsic viscosity values indicating cellulose chains expansion in this solvent

Multi-Scale Characterization of Lyotropic Liquid Crystals Using 2H and Diffusion MRI with Spatial Resolution in Three Dimensions

The ability of lyotropic liquid crystals to form intricate structures on a range of length scales can be utilized for the synthesis of structurally complex inorganic materials, as well as in devices for controlled drug delivery. Here we employ magnetic resonance imaging (MRI) for non-invasive characterization of nano-, micro-, and millimeter scale structures in liquid crystals. The structure is mirrored in the translational and rotational motion of the water, which we assess by measuring spatially resolved self-diffusion tensors and spectra. Our approach differs from previous works in that the MRI parameters are mapped with spatial resolution in all three dimensions, thus allowing for detailed studies of liquid crystals with complex millimeter-scale morphologies that are stable on the measurement time-scale of 10 hours. The data conveys information on the nanometer-scale structure of the liquid crystalline phase, while the combination of diffusion and data permits an estimate of the orientational distribution of micrometer-scale anisotropic domains. We study lamellar phases consisting of the nonionic surfactant C10E3 in O, and follow their structural equilibration after a temperature jump and the cessation of shear. Our experimental approach may be useful for detailed characterization of liquid crystalline materials with structures on multiple length scales, as well as for studying the mechanisms of phase transitions

The promotor and poison effects of the inorganic elements of kraft lignin during hydrotreatment over nimos catalyst

One-pot deoxygenation of kraft lignin to aromatics and hydrocarbons of fuel-range quality is a promising way to improve its added value. Since most of the commercially resourced kraft lignins are impure (Na, S, K, Ca, etc., present as impurities), the effect of these impurities on the deoxygenation activity of a catalyst is critical and was scrutinized in this study using a NiMoS/Al2O3 catalyst. The removal of impurities from the lignin indicated that they obstructed the depolymerization. In addition, they deposited on the catalyst during depolymerization, of which the major element was the alkali metal Na which existed in kraft lignin as Na2S and single-site ionic Na+. Conditional experiments have shown that at lower loadings of impurities on the catalyst, their promotor effect was prevalent, and at their higher loadings, a poisoning effect. The number of moles of impurities, their strength, and the synergism among the impurity elements on the catalyst were the major critical factors responsible for the catalyst’s deactivation. The promotor effects of deposited impurities on the catalyst, however, could counteract the negative effects of impurities on the depolymerization

Factores de riesgo para infección por COVID-19 en personal de salud del Servicio de Emergencia del Hospital María Auxiliadora, marzo - diciembre 2020

Determina los factores de riesgo para infección por COVID-19 en el personal de salud del Servicio de Emergencia del Hospital María Auxiliadora, marzo - diciembre 2020. Investigación observacional y analítica – caso-control, cuya muestra estuvo conformada por 167 trabajadores del servicio de emergencia, divididos en 56 casos y 112 controles, asimismo, se utilizaron como técnica e instrumento de recolección de datos a la encuesta y cuestionario, respectivamente. El antecedente familiar con COVID-19 se asoció de manera significativa a la infección por COVID – 19 (p=0.000, OR=4.242). Los factores labores: personal de salud, realizar labor asistencial en otras instituciones, horas laborales al mes, horas laborales por turno y participación en procedimientos invasivos no fueron significativos para la infección por COVID (p>0.05, respectivamente). Además, se observó que gran parte de los trabajadores infectados con COVID- 19 fueron mujeres (67.3%), tuvieron entre 25-34 años (56.4%), laboraban en el área de tópico especializado (78.2%), le asignaron EPP para el uso durante la jornada (83.6%) y solo el 12.7% usó de forma incorrecta el EPP. Se concluye que el factor patológico de riesgo fue el antecedente familiar con COVID-19 y no se evidenciaron factores laborales de riesgo para infección por COVID-19

Factores de riesgo para COVID-19 en el personal de salud del Servicio de Emergencia del Hospital María Auxiliadora, marzo-diciembre 2020

Objective: To determine the COVID-19 risk factors among the healthcare personnel of the Emergency Department of the Hospital María Auxiliadora from March to December 2020. Materials and methods: An observational, analytical-correlational, cross-sectional and retrospective research. The sample consisted of 117 emergency department workers. The study used surveys as technique and questionnaires as instrument for data collection. Results: Twenty-five point six four percent (25.64 %) of the study participants contracted COVID-19 through a family member, 38.46 % were doctors and 35.90 % worked as medical practitioners in another health institution. Fifty-six point four one percent (56.41 %) worked 150 or more hours per week and 74.36 % worked more than 12 hours per shift. Regarding the personal protective equipment, 78.63 % wore it correctly while 17.90 % used it incorrectly. Also, contact with a family member with COVID-19 was a risk factor for COVID-19 infection (p = 0.000, OR = 5.486). Conclusions: The results indicate that sociodemographic and occupational aspects are not risk factors for COVID-19 infection. However, having contact with an infected family member proved to be a pathological risk factorObjetivo: Determinar los factores de riesgo para presentar COVID-19 del personal de salud del Servicio de Emergencia del Hospital María Auxiliadora en el periodo marzo a diciembre de 2020. Materiales y métodos: Investigación observacional, analítica-correlacional, transversal y retrospectiva. La muestra estuvo conformada por 117 trabajadores del Servicio de Emergencia. La técnica empleada fue la recolección de datos y el instrumento utilizado fue el cuestionario. Resultados: El 25,64 % de los participantes contrajo la COVID-19 por contacto con un familiar enfermo. Los médicos fueron el 38,49 % y el 35,90 % realizaba labor asistencial en otra institución de salud. El 56,41 % de los participantes trabajaba de 150 horas a más por semana; y 74,36 % laboraba más de 12 horas por turno. Respecto al equipo de protección personal, el 78,64 % percibió un uso correcto de este material, y el 17,90 % lo usaba de forma incorrecta. Asimismo, el contacto con un familiar infectado por COVID-19 fue un factor de riesgo para infección por COVID-19 (p = 0,000; OR = 5,486). Conclusiones: Los aspectos sociodemográficos y laborales no se evidenciaron como factores de riesgo para contraer la COVID-19. El factor patológico que sí demostró ser de riesgo fue el contacto con un familiar enfermo

Effluents and residues from industrial sites for carbon dioxide capture: a review

The adverse effects of climate change calls for the rapid transformation of manufacturing processes to decrease the emissions of carbon dioxide. In particular, a lower carbon footprint can be achieved by capturing carbon dioxide at the site of emission. Here we review the use of industrial effluents, waste and residues to capture carbon dioxide. Waste include steelmaking slag, municipal solid waste incinerator ashes, combustion fly ash, black liquor, paper mill waste, mining waste, cement waste, construction and demolition waste, waste from the organic industry, and flue gas desulfurization gypsum waste. Capture capacities range from 2 to 800\ua0kg of carbon dioxide per ton of waste, depending on processes, waste type and conditions. Cement waste and flue gas desulfurization gypsum\ua0waste show the highest capture capacity per ton of waste

Microporous Humins Synthesized in Concentrated Sulfuric Acid Using 5-Hydroxymethyl Furfural

A new class of highly porous organic sorbents called microporous humins is presented. These microporous humins are derived from sustainable and industrially abundant resources, have high heat of CO2 sorption, and could potentially be useful for the separation of carbon dioxide from gas mixtures. Their synthesis involves the polymerization of 5-hydroxymethyl furfural (HMF) in concentrated sulfuric acid and treatment with diethyl ether and heat. In particular, the porosities were tuned by the heat treatment. HMF is a potential platform chemical from biorefineries and a common intermediate in carbohydrate chemistry. A high uptake of CO2 (up to 5.27 mmol/g at 0 degrees C and 1 bar) and high CO2-over-N-2 and CO2-over-CH4 selectivities were observed. The microporous humins were aromatic and structurally amorphous, which was shown in a multipronged approach using C-13 nuclear magnetic resonance and Fourier transform infrared spectroscopies, elemental analysis, and wide-angle X-ray scattering