Description beyond the mean field approximation of an electrolyte confined between two planar metallic electrodes

We study an electrolyte confined in a slab of width $W$ composed of two grounded metallic parallel electrodes. We develop a description of this system in a low coupling regime beyond the mean field (Poisson--Boltzmann) approximation. There are two ways to model the metallic boundaries: as ideal conductors in which the electric potential is zero and it does not fluctuate, or as good conductors in which the average electric potential is zero but the thermal fluctuations of the potential are not zero. This latter model is more realistic. For the ideal conductor model we find that the disjoining pressure is positive behaves as $1/W^3$ for large separations with a prefactor that is universal, i.e. independent of the microscopic constitution of the system. For the good conductor boundaries the disjoining pressure is negative and it has an exponential decay for large $W$. We also compute the density and electric potential profiles inside the electrolyte. These are the same in both models. If the electrolyte is charge asymmetric we find that the system is not locally neutral and that a non-zero potential difference builds up between any electrode and the interior of the system although both electrodes are grounded.Comment: 16 pages, 5 figures, added a new appendix B and a discussion on ideal conductors vs. good conductor

Determination of biosorption mechanism in biomass of agave, using spectroscopic and microscopic techniques for the purification of contaminated water

[Abstract] Lead (Pb2+) and copper (Cu2+) are polluting metals due to their toxicity; however, the extraction of these metals is essential for economic development, so it is important to look for efficient and low-cost alternatives that can remove heavy metals from the various bodies of water. One of the alternatives used in this work is biosorption, for which an agroindustrial waste (epidermis from Agave atrovirens) was used to evaluate the affinity of removal of lead and copper in aqueous solutions; in addition, spectroscopy and microscopy techniques were used to elucidate and corroborate the removal and affinity capacity of the agave epidermis for both metals studied. The optimal pH value for the removal of both metals was 3. The adsorption isotherms yielded a qmax of 25.7 and 8.6 mg/g for lead and copper, respectively. Adjusting to the Langmuir-Freundlich model, the adsorption kinetics were pseudo-second order, and it was found that the equilibrium time was at 140 min. The spectroscopy and microscopy analyses corroborated the affinity between metals and functional groups of the agave, as well as with the elemental analysis, which reported 17.38% of lead and 4.25% of copper.[Resumen] El plomo (Pb2+) y el cobre (Cu2+) son metales contaminantes debido a su toxicidad; sin embargo, la extracción de estos metales es indispensable para el desarrollo económico, por lo que es importante buscar alternativas eficientes y de bajo costo que puedan remover metales pesados de los diversos cuerpos de agua. Una de las alternativas utilizadas en este trabajo es la biosorción, para la cual se utilizó un residuo agroindustrial (epidermis de Agave atrovirens), para evaluar la afinidad de remoción del plomo y cobre en soluciones acuosas; adicionalmente, se emplearon técnicas de espesctroscopía y microscopía que permitieron elucidar y corroborar la capacidad de remoción y afinidad que tuvo la epidermis de A. atrovirens para ambos metales estudiados. El valor óptimo de pH para la remoción de ambos metales fue 3. Las isotermas de adsorción arrojaron una qmax de 25.7 y 8.6 mg/g para el plomo y cobre, respectivamente. Ajustando al modelo de Langmuir-Freundlich, las cinéticas de adsorción resultaron de pseudo-segundo orden, se encontró que el tiempo de equilibrio es a los 140 min. El análisis espectroscópico y microscópico, corroboró la afinidad entre metales y grupos funcionales del agave, así como con el análisis elemental, el cual reportó 17.38% de plomo y 4.25% de cobre

Wigner Surmise For Domain Systems

In random matrix theory, the spacing distribution functions $p^{(n)}(s)$ are well fitted by the Wigner surmise and its generalizations. In this approximation the spacing functions are completely described by the behavior of the exact functions in the limits s->0 and s->infinity. Most non equilibrium systems do not have analytical solutions for the spacing distribution and correlation functions. Because of that, we explore the possibility to use the Wigner surmise approximation in these systems. We found that this approximation provides a first approach to the statistical behavior of complex systems, in particular we use it to find an analytical approximation to the nearest neighbor distribution of the annihilation random walk

Collective modes and correlations in one-component plasmas

The static and time-dependent potential and surface charge correlations in a plasma with a boundary are computed for different shapes of the boundary. The case of a spheroidal or spherical one-component plasma is studied in detail because experimental results are available for such systems. Also, since there is some knowlegde both experimental and theoretical about the electrostatic collective modes of these plasmas, the time-dependent correlations are computed using a method involving these modes.Comment: 20 pages, plain TeX, submitted to Phys. Rev.

Demand response program implementation methodology: A Colombian study case

The industrialization and urbanization are responsible for Greenhouse Gas (GHG) emissions and could generate energy shortage problems. The application of Demand Response (DR) programs enables the user to be empowered towards a conscious consumption of energy, allowing the reduction or displacement of the demand for electrical energy, contributing to the sustainable development of the sector and the operational efficiency of the electrical system, among others. A reference framework for this type of program is detailed along with a literature survey applied to the Colombian case. The considerations on the design of a methodology to the implementation of the DR pilot, considering if the pilot is in an interconnected system zone or non-interconnected system zone and the application of the design methodology in the modeling of three DR pilots in Colombia is presented. For the modeling of the pilots, the characteristics of the area and the base consumption of the users are considered, and the characteristics and assumptions of the pilot are also defined. Furthermore, the DR pilot in each zone considering four types of users is detailed. The results show the potential for energy reduction and displacement in different time bands for each zone, which allows determining the assessment of the benefits from a technical, financial, and environmental point of view, and the costs of each pilot in monetary terms, it not to compare the pilots with each other, but to illustrate the values that must be taken into account in those analyses. The sensitivity analysis of each pilot was also carried out, considering the variation of the benefit/cost relationship with the energy rate in peak hours vs. off-peak hours and the base energy rate in the area. The sensitivity analysis shows that, when varying the level of energy demand response and the number of pilot participants, the values are presented when the benefit/cost ratio is greater than 1. In addition, the paper provides specific recommendations related to the design of a methodology and the implementation in a pilot DR using simulation

Caffeine Encapsulation in Metal Organic Framework MIL-53(Al) at Pilot Plant Scale for Preparation of Polyamide Textile Fibers with Cosmetic Properties

Currently in the marketplace, we can find clothing items able to release skin-friendly ingredients while wearing them. These innovative products with high-added value are based on microencapsulation technology. In this work, due to its lightness, flexibility, porosity, chemical affinity and adsorption capacity, metal-organic framework (MOF) MIL-53(Al) was the selected microcapsule to be synthesized at a large scale and subsequent caffeine encapsulation. The synthesis conditions (molar ratio of reactants, solvents used, reaction time, temperature, pressure reached in the reactor and activation treatment to enhance the encapsulation capacity) were optimized by screening various scaling-up reactor volumes (from lab-scale of 40 mL to pilot plant production of 3.75 L). Two types of Al salts (Al(NO3)3·9H2O from the original recipe and Al2(SO4)3 as commercial SUFAL 8.2) were employed. The liporeductor cosmetic caffeine was selected as the active molecule for encapsulation. Caffeine (38 wt %) was incorporated in CAF@MIL-53(Al) microcapsules, as analyzed by TGA and corroborated by GC/MS and UV-vis after additive extraction. CAF@MIL-53(Al) microcapsules showed a controlled release of caffeine during 6 days at 25 °C (up to 22% of the initial caffeine). These capsules were incorporated through an industrial spinning process (with temperatures up to 260 °C) to manufacture PA-6 fibers with cosmetic properties. Up to 0.7 wt % of capsules were successfully incorporated into the fibers hosting 1700 ppm of caffeine. Fabrics were submitted to scouring, staining, and washing processes, detecting the presence of caffeine in the cosmetic fiber. © 2022 The Authors. Published by American Chemical Society

Association of shivering threshold time with body composition and brown adipose tissue in young adults

Purpose: Brown adipose tissue (BAT) increases metabolic heat production in response to cold exposure. Body size and composition are involved in the human cold response, yet the influence of BAT herein have not fully been explored. Here, we aimed to study the association of the cold-induced shivering threshold time with body composition, BAT, the perception of shivering and skin temperature in young adults. Methods: 110 young healthy adults (81 females; age = 21.7 ± 2.1 years, BMI = 24.2 ± 4.3 kg/m2) underwent 2 h of individualized cooling, followed by the quantification of BAT using a18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography-computed tomography (PET-CT) scan. Body mass index (BMI), lean mass, fat mass and body surface area (BSA) were also measured. Shivering threshold time was defined as the time until shivering occurred using an individualized cooling protocol. Results: The shivering threshold time was on average 116.1 min for males and 125.8 min for females, and was positively associated to BMI (β = 3.106; R2 = 0.141; p = 0.001), lean mass (β = 2.295; R2 = 0.128; p = 0.001) and fat mass (β = 1.492; R2 = 0.121; p = 0.001) in females, but not in males (all p ≥ 0.409). The shivering threshold time was positively associated with BSA in males (p = 0.047) and females (p = 0.001), but it was not associated with BAT volume or [18F]FDG uptake nor with the perception of shivering and skin temperature perception in both sexes. Conclusion: The shivering threshold time is positively associated with whole-body adiposity and lean mass in females, but not in males. The shivering threshold time was positively associated with BSA, but no association was observed with BAT nor with the perception of shivering or skin temperature. Future research should consider the influence of body composition when applying cooling protocols among individuals with different phenotypical features.Spanish Government PI13/01393 PTA 12264-IRetos de la Sociedad DEP 2016-79512-REuropean CommissionSpanish Government FPU 13/03410Fundacion Iberoamericana de Nutricion (FINUT)Redes Tematicas de Investigacion Cooperativa RETIC Red SAMID RD16/0022AstraZenecaUniversity of Granada Plan Propio de Investigacion 2016 - Excellence actions: Unit of Excellence on Exercise and Health (UCEES)Plan Propio de Investigacion 2018: Programa ContratosPuenteJunta de Andalucia, Consejeria de Conocimiento, Investigacion y Universidades (ERDF) SOMM17/6107/UGRFundacion Carolina C.2016-574,961Fundacion Alfonso Martin EscuderoMinisterio de Universidades y la Union Europea-NextGenerationEU RR_C_2021_0

Screening of classical Casimir forces by electrolytes in semi-infinite geometries

We study the electrostatic Casimir effect and related phenomena in equilibrium statistical mechanics of classical (non-quantum) charged fluids. The prototype model consists of two identical dielectric slabs in empty space (the pure Casimir effect) or in the presence of an electrolyte between the slabs. In the latter case, it is generally believed that the long-ranged Casimir force due to thermal fluctuations in the slabs is screened by the electrolyte into some residual short-ranged force. The screening mechanism is based on a "separation hypothesis": thermal fluctuations of the electrostatic field in the slabs can be treated separately from the pure image effects of the "inert" slabs on the electrolyte particles. In this paper, by using a phenomenological approach under certain conditions, the separation hypothesis is shown to be valid. The phenomenology is tested on a microscopic model in which the conducting slabs and the electrolyte are modelled by the symmetric Coulomb gases of point-like charges with different particle fugacities. The model is solved in the high-temperature Debye-H\"uckel limit (in two and three dimensions) and at the free fermion point of the Thirring representation of the two-dimensional Coulomb gas. The Debye-H\"uckel theory of a Coulomb gas between dielectric walls is also solved.Comment: 25 pages, 2 figure

Chicken litter: A waste or a source of chemicals? Fast pyrolysis and hydrothermal conversion as alternatives in the valorisation of poultry waste

Poultry production is one of the main and fastest developing branches of the agri-food industry in the world. Chicken litter (ChL) is the most abundant waste from this industry and requires alternative treatments to help mitigate the environmental impacts of improper disposal. Fast pyrolysis and hydrothermal conversion are two recognized thermochemical approaches for the transformation of different types of biomasses, including agro-industrial waste. Fast pyrolysis takes place at atmospheric pressure or under vacuum at moderate to high temperatures (400–800 °C) in the absence of oxygen and requires drying of the feedstock, whereas hydrothermal conversion is a low temperature (180–300 °C) and high pressure (up to 30 MPa) process that takes place in liquid water and particularly suited for moist materials. In this work, we present experimental results that provide a comparison of bio-oils produced by fast pyrolysis and hydrothermal conversion of ChL. In addition, the composition of the pyrolytic oils from ChL is compared with the data obtained from rice husk (the main component of ChL), studied previously. Fast pyrolysis experiments were carried out in a bed reactor at temperatures ranging from 400° to 700°C and at two reaction times of 20- and 40-min. Phenols and other oxygenated compounds were the main families of chemicals present in the bio-oils. Among oxygenated derivatives, fatty acids were predominant. Hydrothermal conversion experiments were performed between 220 and 240 °C for 20- and 40- min and the oil fraction was obtained by evaporation of water from the reaction mixture followed by freeze-drying. These bioliquids were found to be concentrated in fatty acids, especially palmitic acid.EEA Concepción del UruguayFil: Pachón Gómez, Erica M. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Pachón Gómez, Erica M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Domínguez, Rodrigo E. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Domínguez, Rodrigo E. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: López, Débora A. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: López, Débora A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Téllez, Jhoan F. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Téllez, Jhoan F. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Fisicoquímica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Téllez, Jhoan F. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Marino, Marcos D. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Marino, Marcos D. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Almada, Natalia Soledad. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; Argentina.Fil: Gange, Juan Martí­n. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Moyano, E. Laura. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica. Instituto de Investigaciones en Fisicoquímica de Córdoba; ArgentinaFil: Moyano, E. Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Fisicoquímica de Córdoba; Argentin

Overweight and obesity status from the prenatal period to adolescence and its association with non- alcoholic fatty liver disease in young adults: cohort study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/16/bjo16199-sup-0005-ICMJES2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/15/bjo16199-sup-0012-ICMJES12.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/14/bjo16199_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/13/bjo16199-sup-0010-ICMJES10.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/12/bjo16199-sup-0002-TableS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/11/bjo16199.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/10/bjo16199-sup-0007-ICMJES4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/9/bjo16199-sup-0008-ICMJES5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/8/bjo16199-sup-0006-ICMJES3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/7/bjo16199-sup-0003-AppendixS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/6/bjo16199-sup-0011-ICMJES11.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/5/bjo16199-sup-0013-ICMJES13.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/4/bjo16199-sup-0014-ICMJES14.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/3/bjo16199-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/2/bjo16199-sup-0009-ICMJES6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156435/1/bjo16199-sup-0004-ICMJES1.pd