Kinetic modeling of the hydrotreatment of light cycle oil/diesel

A rigorous kinetic model of hydrodesulfurization (HDS) of complex mixtures such as light cycle oil (LCO) or diesel has been developed. An experimental setup was constructed to investigate the hydrotreatment of complex mixtures. The hydrodesulfurization of LCO on a commercial CoMo/Al2O3 (IMP) catalyst was investigated in a Robinson Mahoney perfectly mixed flow stationary basket reactor. An experimental investigation of the HDS of the dibenzothiophene (DBT) and substituted dibenzothiophenes in the LCO was carried out at temperatures between 290 and 330°C, space time for dibenzothiophene (W/F0 DBT) between 1000 and 6500 kgcat-h/kmol, and H2/HC molar ratio constant of 2.8. To avoid having to deal with a huge number of parameters in the model, a methodology based on structural contributions was applied. DENs and DENt are the denominators of the Hougen-Watson rate expressions for hydrodesulfurization of dibenzothiophene (DBT) and methyl-substituted dibenzothiophenes contained in the LCO. Both denominators comprise the concentration of all adsorbing species of the LCO multiplied by their adsorption equilibrium constants. The estimation of the denominators DENs and DENt was performed using the Levenberg-Marquardt algorithm and the results in terms of conversion for DBT, biphenyl and cyclohexylbenzene obtained in the hydrodesulfurization of the LCO. The evolution of DENs and DENt values with the composition was calculated for each LCO experiment. Structural contributions were taken from Vanrysselberghe and Froment for hydrogenolysis and hydrogenation of methyl-substituted dibenzothiophenes with a significant reduction in the number of parameters to be estimated in the HDS of the LCO. The multiplication factors, fsDBT, which are products of structural contributions for hydrogenolysis and hydrogenation of the mono- and dimethyl-dibenzothiophenes were also taken from Vanrysselberghe and Froment. These multiplication factors are based on experimental results with model components such as DBT, 4-Methyl dibenzothiophene and 4,6-Dimethyl dibenzothiophene. The results obtained in the modeling are in good agreement with the experimental data because the model reproduces very well the observed total conversions of DBT, conversions of DBT into biphenyl and conversions of DBT into cyclohexylbenzene as a function of temperature

Study of star-forming galaxies in SDSS up to redshift 0.4: I. Metallicity evolution

The chemical composition of the gas in galaxies versus cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required link between local and high redshift universe. In this work we focus on the metallicity of the gas of star-forming galaxies at low redshift, looking for signs of chemical evolution. To analyze the metallicity contents star-forming galaxies of similar luminosities and masses at different redshifts. With this purpose, we present a study of the metallicity of relatively massive (log(M_star/M_sun)>10.5) star forming galaxies from SDSS--DR5 (Sloan Digital Sky Survey--Data Release 5), using different redshift intervals from 0.04 to 0.4. We used data processed with the STARLIGHT spectral synthesis code, correcting the fluxes for dust extinction, estimating metallicities using the R_23 method, and segregating the samples with respect to the value of the [NII]6583/[OII]3727 line ratio in order to break the R_23 degeneracy selecting the upper branch. We analyze the luminosity and mass-metallicity relations, and the effect of the Sloan fiber diameter looking for possible biases. By dividing our redshift samples in intervals of similar magnitude and comparing them, significant signs of metallicity evolution are found. Metallicity correlates inversely with redshift: from redshift 0 to 0.4 a decrement of ~0.1 dex in 12+log(O/H) is found.Comment: 11 pages, 9 figures, Accepted for publication in A&

Radiolysis of the Glycolaldehyde-Na+Montmor- illonite and Glycolaldehyde-Fe3+Montmorillonite Systems in Aqueous Suspension under Gamma Radiation Fields: Implications in Chemical Evolution

The stability and reactivity of organic molecules with biological and pre-biological significance in primitive conditions are of paramount importance in chemical evolution studies. Sugars are an essential component in biological systems for the different roles that they play in living beings. The objective of the present work is to study the gamma radiolysis of aqueous solutions of glycolaldehyde, the simplest sugar and aqueous suspensions of glycolaldehyde-Na+-montmorillonite and glycolaldehyde-Fe3+Montmorillonite. Our results indicate that the radiolysis of the aqueous solutions of glycolaldehyde (0.03M), oxygen free, mainly produce the linear dimer known as eritriol (122 g/mol) and a sugar-like compound with six carbon atoms (180 g/mol). The experiments with the clay suspensions show that clays can adsorb glycolaldehyde and protect it from gamma irradiation. Additionally, it was observed that depending on the cation present in the clay, the percentage and the product (monomer or cyclic dimer) adsorption was different. In the case of Fe3+ Montmorillonite, this clay catalyzed the decomposition of glycolaldehyde, forming small amounts non-identified products. The analysis of these systems was performed by ATR-FTIR, UV spectroscopy, liquid chromatography (UHPLC-UV), and HPLC coupled to a mass spectrometry

Study of L-Glutamic Acid in Solid State for its Possible Use as a Gamma Dosimeter at Different Temperatures (77, 195 and 295 K)

The experimental response of the dosimeter as a function of the irradiation temperature plays an important role, and this effect has consequences in the practical applications of dosimetry. In this work, L-glutamic acid (2-aminopentanedioic acid) is proposed to be a good response, easy to handle, and a cheap gamma dosimeter. For this purpose, polycrystalline samples were irradiated with gamma rays at 77, 195, and 295 K and doses in the kiloGray range (43–230 kGy). The potential use of the glutamic acid system as a chemical dosimeter is based on the formation of stable free radicals when the amino acid is exposed to ionizing radiation. The observed species in these experiments were attributed to deamination and decarboxylation reactions that were studied using electron spin resonance (ESR). The results indicate that the analysis generates a linear response as the irradiation dose increases in a reliable range for industrial and research purposes at three different temperatures

Influence of exercise on the metabolic profile caused by 28 days of bed rest with energy deficit and amino acid supplementation in healthy men

Objective: Muscle loss and metabolic changes occur with disuse [i.e. bed rest (BR)]. We hypothesized that BR would lead to a metabolically unhealthy profile defined by: increased circulating tumor necrosis factor (TNF)-α, decreased circulating insulin-like-growth-factor (IGF)-1, decreased HDL-cholesterol, and decreased muscle density (MD; measured by mid-thigh computerized tomography).  Methods: We investigated the metabolic profile after 28 days of BR with 8±6% energy deficit in male individuals (30-55 years) randomized to resistance exercise with amino acid supplementation (RT, n=24) or amino acid supplementation alone (EAA, n=7). Upper and lower body exercises were performed in the horizontal position. Blood samples were taken at baseline, after 28 days of BR and 14 days of recovery.  Results: We found a shift toward a metabolically unfavourable profile after BR [compared to baseline (BLN)] in both groups as shown by decreased HDL-cholesterol levels (EAA: BLN: 39±4 vs. BR: 32±2 mg/dL, RT: BLN: 39±1 vs. BR: 32±1 mg/dL; p<0.001) and Low MD (EAA: BLN: 27±4 vs. BR: 22±3 cm2, RT: BLN: 28±2 vs. BR: 23±2 cm2; p<0.001). A healthier metabolic profile was maintained with exercise, including NormalMD (EAA: BLN: 124±6 vs. BR: 110±5 cm2, RT: BLN: 132±3 vs. BR: 131±4 cm2; p<0.001, time-by-group); although, exercise did not completely alleviate the unfavourable metabolic changes seen with BR. Interestingly, both groups had increased plasma IGF-1 levels (EAA: BLN:168±22 vs. BR 213±20 ng/mL, RT: BLN:180±10 vs. BR: 219±13 ng/mL; p<0.001) and neither group showed TNFα changes (p>0.05).  Conclusions: We conclude that RT can be incorporated to potentially offset the metabolic complications of BR

COVID-19's impacts on global value chains, as seen in the apparel industry

Abstract: Motivation: The COVID‐19 pandemic has massively disrupted international trade and global value chains. Impacts, however, differ across regions and industries. This article contributes to a better understanding of the scale of disruptions to industries and value chains integral to the economies of and livelihoods in developing countries, and what role policy can play to mitigate harm. Purpose: This article aims to: (1) analyse and characterize disruptions to the global apparel value chain caused by the COVID‐19 pandemic, focusing on how developing countries have been impacted, and; (2) identify key policies to support a resilient, inclusive and sustainable recovery. Approach and methods: We review COVID‐19 related reports published by international and non‐governmental organizations, international trade and production statistics, industry surveys and media reports. We frame our analysis predominantly within the Global Value Chains literature. Findings: The global apparel value chain has been severely disrupted by the pandemic, owing to direct effects of sickness on workers in factories, reduced output of materials—cloth, thread, etc.—used to fabricate clothing, and to reduced demand for apparel in high‐income countries. Developing countries are suffering disproportionately in terms of profits, wages, job security and job safety. Women workers in the apparel chain have been hit especially hard, not only because most workers in the chain are women, but also because they have experienced increasing unpaid care work and higher risk of gender‐based violence. Policy implications: Five key areas of policy to support a resilient, inclusive and sustainable recovery stand out: (1) delivering emergency responses to ensure firm survival and the protection of workers’ livelihoods; (2) reformulating FDI attraction strategies and promoting market diversification; (3) supporting technology adoption and skills development; (4) deploying labour standards to improve workers’ conditions and strengthening social protection systems; and (5) adopting gender‐sensitive responses

Study of Solid-State Radiolysis of Behenic, Fumaric, and Sebacic Acids for their Possible Use as Gamma Dosimeters Measured Via ATR-FT-IR Spectroscopy

The intensive use of ionizing radiation has promoted the constant investigation of adequate dosimetric systems in the measurement of doses applied in irradiated products. The objective of this work is to propose gamma dosimetric systems, using carboxylic acids in a solid state and measuring the change via infrared spectroscopy (carboxylic acid/ ATR-FT-IR1). We worked with three systems: (1) behenic acid/ATR-FT-IR, (2) sebacic acid/ATR-FT-IR, and (3) fumaric acid/ATR-FT-IR. The change in absorbance corresponding to the stretching vibration frequency of the carbonyl group to the absorbed dose (in the range of kGy) was measured. The results showed that the acid/ATR-FT-IR systems have a linear response with respect to the absorbed dose, for behenic acid/ATR-FT-IR from 0 to 122 kGy, for ATR-FT-IR sebacic acid from 0 to 61 kGy, and for fumaric acid/ATR-FT-IR from 0 to 34 kGy. The results indicated that the linear response of the absorbance dose in the three systems allows us to continue studying other variables to be able to propose them as chemical dosimeters

Spectrophotometric Study of Polymeric DyesGels After a Gamma Irradiation Process for its Possible Use as a Radiation Dosimeter

This work aims to evaluate a dosimetric system composed of green malachite supported in agarose. Previous work showed that solutions of green malachite irradiated at 1 to 40 kGy present a linear behavior. This system is a gel composed of green malachite (2.5×10–3 M), sodium benzoate (1%),and agarose (1%) that was exposed tovarious doses of gamma irradiation. The irradiated systems were measured with a UV-V is spectrophotometer at 619 nm. Experimental parameters (such as dose rate, doses, and temperature) were controlled and optimized for reproducible and reliable results. More studies are needed to propose a dosimeter in the system in the range of 1.8 to 4.0 kGy

Enzymatic extraction of hydroxycinnamic acids from coffee pulp

Ferulic, caffeic, p-coumaric and chlorogenic acids are classified as hydroxycinnamic acids, presenting anticarcinogenic, anti-inflammatory and antioxidant properties. In this work, enzymatic extraction has been studied in order to extract high value-added products like hydroxycinnamic acids from coffee pulp. A commercial pectinase and enzyme extract produced by Rhizomucor pusillus strain 23aIV in solid-state fermentation using olive oil or coffee pulp (CP) as an inducer of the feruloyl esterase activity were evaluated separately and mixed. The total content (covalently linked and free) of ferulic, caffeic, p-coumaric and chlorogenic acids was 5276 mg per kg of coffee pulp. Distribution was as follows (in %): chlorogenic acid 58.7, caffeic acid 37.6, ferulic acid 2.1 and p-coumaric acid 1.5. Most of the hydroxycinnamic acids were covalently bound to the cell wall (in %): p-coumaric acid 97.2, caffeic acid 94.4, chlorogenic acid 76.9 and ferulic acid 73.4. The content of covalently linked hydroxycinnamic acid was used to calculate the enzyme extraction yield. The maximum carbon dioxide rate for the solid-state fermentation using olive oil as an inducer was higher and it was reached in a short cultivation time. Nevertheless, the feruloyl esterase (FAE) activity (units per mg of protein) obtained in the fermentation using CP as an inducer was 31.8 % higher in comparison with that obtained in the fermentation using olive oil as the inducer. To our knowledge, this is the first report indicating the composition of both esterified and free ferulic, caffeic, p-coumaric and chlorogenic acids in coffee pulp. The highest yield of extraction of hydroxycinnamic acids was obtained by mixing the produced enzyme extract using coffee pulp as an inducer and a commercial pectinase. Extraction yields were as follows (in %): chlorogenic acid 54.4, ferulic acid 19.8, p-coumaric acid 7.2 and caffeic acid 2.3. An important increase in the added value of coffee pulp was mainly due to the extraction of chlorogenic acid