Sustainable DMC production from CO2 and renewable ammonia and methanol

[EN]One of the main goals of the green chemistry is to develop sustainable and less hazardous chemical processes and products. Dimethyl carbonate (DMC) is attracting attention due to the wide variety of applications and the possibility of producing it from carbon dioxide. In this work, the DMC production process via urea has been optimized. Two main sections can be distinguished: the synthesis of urea and the production of DMC. An equation based approach is used to model the system. The DMC production from renewable ammonia/methanol/CO2 presents a promising production cost, around 520 €/t. The production of urea alone has also been evaluated in this work. A sensitivity analysis is carried out showing the influence of the methanol price in the DMC cost and the ammonia price in the urea cost. A simplified sustainability index is used to evaluate the environmental performance of urea/DMC production

Pemodelan Dekomposisi Ammonium Carbamate pada Tekanan Tinggi di Pabrik Urea

Urea acts as a nitrogen-based fertilizer to boost crop production and prevent a worldwide hunger crisis. Considering ways to make urea production in existing plants more environmentally friendly, a detailed study has been conducted on the high-pressure stripper, in which the equipment uses intensive energy to decompose ammonium carbamate. The mathematical model was prepared using the two-film theory. The UNIQUAC and Redlich-Kwong equations of state have been used to express nonideality in the NH3-CO2-H2O-urea system under high pressure and temperature circumstances. Due to the lack of transport properties in extreme conditions, the properties were estimated using a theoretical method. The present study obtained the mass-transfer coefficient in dimensionless form  and . Moreover, the heat-transfer coefficient was calculated using the Chilton-Colburn analogy. The proposed model result matches what is expected with the commercial plant data. Furthermore, with less than 5% relative deviations, the model deserves significant consideration for any practical use in high-pressure stripper simulatio

Virtual screening for inhibitors of the human TSLP:TSLPR interaction

The pro-inflammatory cytokine thymic stromal lymphopoietin (TSLP) plays a pivotal role in the pathophysiology of various allergy disorders that are mediated by type 2 helper T cell (Th2) responses, such as asthma and atopic dermatitis. TSLP forms a ternary complex with the TSLP receptor (TSLPR) and the interleukin-7-receptor subunit alpha (IL-7Ra), thereby activating a signaling cascade that culminates in the release of pro-inflammatory mediators. In this study, we conducted an in silico characterization of the TSLP: TSLPR complex to investigate the drugability of this complex. Two commercially available fragment libraries were screened computationally for possible inhibitors and a selection of fragments was subsequently tested in vitro. The screening setup consisted of two orthogonal assays measuring TSLP binding to TSLPR: a BLI-based assay and a biochemical assay based on a TSLP: alkaline phosphatase fusion protein. Four fragments pertaining to diverse chemical classes were identified to reduce TSLP: TSLPR complex formation to less than 75% in millimolar concentrations. We have used unbiased molecular dynamics simulations to develop a Markov state model that characterized the binding pathway of the most interesting compound. This work provides a proof-ofprinciple for use of fragments in the inhibition of TSLP: TSLPR complexation

Pemodelan Dekomposisi Ammonium Carbamate pada Tekanan Tinggi di Pabrik Urea

Urea acts as a nitrogen-based fertilizer to boost crop production and prevent a worldwide hunger crisis. Considering ways to make urea production in existing plants more environmentally friendly, a detailed study has been conducted on the high-pressure stripper, in which the equipment uses intensive energy to decompose ammonium carbamate. The mathematical model was prepared using the two-film theory. The UNIQUAC and Redlich-Kwong equations of state have been used to express nonideality in the NH3-CO2-H2O-urea system under high pressure and temperature circumstances. Due to the lack of transport properties in extreme conditions, the properties were estimated using a theoretical method. The present study obtained the mass-transfer coefficient in dimensionless form  and . Moreover, the heat-transfer coefficient was calculated using the Chilton-Colburn analogy. The proposed model result matches what is expected with the commercial plant data. Furthermore, with less than 5% relative deviations, the model deserves significant consideration for any practical use in high-pressure stripper simulatio

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 336)

This bibliography lists 111 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during April 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

On the decarbonization of chemical and energy industries: Power-to-X design strategies

Tesis por compendio de publicaciones[ES]Hoy en día, la preocupación por la sostenibilidad está dando lugar a todo un nuevo sistema económico. Este nuevo paradigma afecta a todos los sectores como la agricultura, la industria, el sector financiero, etc. Dos de los más afectados son la industria química y el sistema energético debido a su configuración actual y, estos dos sectores son particularmente estudiados en esta tesis. En cuanto a la industria química, la producción electroquímica es uno de los métodos más atractivos para producir productos químicos de forma sostenible dejando atrás la producción tradicional no renovable. En esta tesis se ha prestado especial atención a la producción sostenible de amoníaco. Se han evaluado dos rutas diferentes, la primera utiliza la electrólisis del agua y evalúa diferentes tecnologías de separación del aire en función de la escala, y la segunda utiliza la biomasa como materia prima. Utilizando estos productos electroquímicos, es posible construir una nueva industria química sostenible. En esta tesis se propone la síntesis de carbo- nato de dimetilo (DMC) utilizando metanol renovable, amoníaco y dióxido de carbono capturado. En cuanto al sector energético, la introducción de fuentes renovables es esencial para alcanzar los objetivos propuestos. En este punto, el almacenamiento de energía será crucial para garantizar la satisfacción de la demanda debido a las fluctuaciones inherentes a las energías solar y eólica. Esta tesis se centra en la evaluación de productos químicos como forma potencial de almacenamiento o como vectores de energía. Se estudia la transformación del amoníaco en electricidad a escala de proceso proporcionando los resultados necesarios para implementar esta alternativa a escala de red. El diseño y el funcionamiento de las insta- laciones basadas en renovables se abordan simultáneamente, incluyendo la ubicación de las unidades debido a que los recursos renovables estan distri- buidos. Se propone un sistema integrado para utilizar productos químicos como vectores energéticos para diferentes aplicaciones energéticas en una región de España, calculando las capacidades, la operación y la ubicación óptima de las instalaciones. Además, se realiza la integración de diferentes energías renovables intermitentes y no intermitentes junto con diferentes tecnologías de almacenamiento desde una perspectiva económica y social para satisfacer una determinada demanda eléctrica. Todos estos sistemas y herramientas propuestos contribuyen a crear un escenario futuro en el que los sectores químico y energético se transforman para ser menos impactantes en el medio ambiente que nos rode

Sex-specific computational models of the spontaneously hypertensive rat kidneys: factors affecting nitric oxide bioavailability

Sex-specific computational models of the spontaneously hypertensive rat kidneys: factors affecting nitric oxide bioavailability. Am J Physiol Renal Physiol 313: F174 –F183, 2017. First published March 29, 2017; doi:10.1152/ajprenal.00482.2016.—The goals of this study were to 1) develop a computational model of solute transport and oxygenation in the kidney of the female spontaneously hypertensive rat (SHR), and 2) apply that model to investigate sex differences in nitric oxide (NO) levels in SHR and their effects on medullary oxygenation and oxidative stress. To accomplish these goals, we first measured NO synthase (NOS) 1 and NOS3 protein expression levels in total renal microvessels of male and female SHR. We found that the expression of both NOS1 and NOS3 is higher in the renal vasculature of females compared with males. To predict the implications of that finding on medullary oxygenation and oxidative stress levels, we developed a detailed computational model of the female SHR kidney. The model was based on a published male kidney model and represents solute transport and the biochemical reactions among O2, NO, and superoxide (O2 ) in the renal medulla. Model simulations conducted using both male and female SHR kidney models predicted significant radial gradients in interstitial fluid oxygen tension (PO2) and NO and O2 concentration in the outer medulla and upper inner medulla. The models also predicted that increases in endothelial NO-generating capacity, even when limited to specific vascular segments, may substantially raise medullary NO and PO2 levels. Other potential sex differences in SHR, including O2 production rate, are predicted to significantly impact oxidative stress levels, but effects on NO concentration and PO2 are limited.This research was supported by the National Institute of Diabetes and Digestive and Kidney Diseases Grant R01-DK-106102 to A. T. Layton, and by American Heart Association Grant 14GRNT20480199 to J. C. Sullivan. (R01-DK-106102 - National Institute of Diabetes and Digestive and Kidney Diseases; 14GRNT20480199 - American Heart Association)Accepted manuscrip

Process Integration of Calcium Looping Technology

Around 36 gigatonnes of CO₂ are released into the atmosphere every year. Mitigation of CO₂ emissions is essential in reducing the rising level of greenhouse gas emissions and associated climate change. Calcium Looping Process (CLP) is one of the promising technologies developed as part of the continuous efforts for Carbon Capture and Utilization (CCU). It is essentially a CO₂ capture process that utilizes calcium oxide (CaO) as a sorbent for the removal of CO₂, producing a concentrated stream of CO₂ (~99%) that is suitable for storage and reuse is produced in this process. Although still in the pilot stage, CLP presents several advantages over conventional carbon capture systems like amine-scrubbing. These advantages include low cost of the sorbent and relative ease of bolt-on retrofitting of existing power plants and industrial processes. The objective of this work is to use mass and energy integration to couple CLP with industrial facilities and power plants in order to enhance industrial symbiosis and reduce cost. Special attention is given to plants that generate large amount of CO₂ and/or provide excess heat that can be used in driving CLP. A case study was solved to assess the integration of CLP with candidate processes including power plants, cement production, gas-to-liquid (GTL) facility, and ammonia synthesis. The captured CO₂ can be re-utilized in CO₂ sinks that utilize CO₂ as a raw material for making chemicals. This use of CO₂ as a chemical feedstock provides a suitable alternative to sequestration and storage. The CO₂ sinks considered in the case study include the production of: urea, polymer, methanol and acetic acid. The solution to the case study shows the merits for integration of a GTL plant with CLP to supply CO₂ for the production of a polymer, methanol and acetic acid. Additionally, the captured CO₂ stream from the ammonia plant is integrated with urea production. Excess heat from the GTL facility and the power plant were also used. Cogeneration of power and heat improves the economic feasibility of the integrated system. The highlights of this symbiosis are the re-use of waste calcium oxide from the cement plant, utilization of waste heat and reduction of CO₂ emissions and raw-material usage due to utilization of the captured CO

Pathogenic mutations in the hydrophobic core of the human prion protein can promote structural instability and misfolding

Transmissible spongiform encephalopathies, or prion diseases, are caused by misfolding and aggregation of the prion protein PrP. These diseases can be hereditary in humans and four of the many disease-associated missense mutants of PrP are in the hydrophobic core: V180I, F198S, V203I and V210I. The T183A mutation is related to the hydrophobic core mutants as it is close to the hydrophobic core and known to cause instability. We have performed extensive molecular dynamics simulations of these five PrP mutants and compared their dynamics and conformations to wild-type PrP. The simulations highlight the changes that occur upon introduction of mutations and help to rationalize experimental findings. Changes can occur around the mutation site, but they can also be propagated over long distances. In particular, the F198S and T183A mutations lead to increased flexibility in parts of the structure that are normally stable, and the short β-sheet moves away from the rest of the protein. Mutations V180I, V210I and, to a lesser extent, V203I cause changes similar to those observed upon lowering the pH, which has been linked to misfolding. Early misfolding is observed in one V180I simulation. Overall, mutations in the hydrophobic core have a significant effect on the dynamics and stability of PrP, including the propensity to misfold, which helps to explain their role in the development of familial prion diseases