Kinetics of Magnesium Extraction from Activated Serpentine by Carbonic Acid

Ex situ mineral carbonation heavily depends on the ability of cations (e.g., Mg2+) to form stable carbonates. The abundant serpentine minerals contain sufficient magnesium to fill this role. Serpentine partially dehydroxylated by thermal pre-treatment, which has a nearly amorphous state (meta-serpentine), has been shown to enhance overall carbonation yield. However, the dissolution kinetics of meta-serpentine under the carbonic acid system remains largely unresolved within the literature. In this thesis, the kinetics of magnesium extraction from thermally activated serpentine under the CO2-H2O system was investigated for the purpose of identifying the underlying rate-limiting mechanisms. The extraction rates of magnesium and silica from thermally activated serpentine were measured over a wide range of conditions, covering different reaction temperatures (303–473 K), pressures (10–160 bar), mass loading factors (0.03–1 min), and particle sizes (20–180 μm) using a continuous fluidised bed reactor under the saturated CO2-H2O system. Extraction of silica almost always followed the equilibrium solubility of amorphous silica. Magnesium is believed to be released by the protons associated with the MgO-CO2-H2O equilibria. The kinetic implications of all the measured magnesium extraction rates were evaluated using a far-from-equilibrium pH dependence mechanism. At undersaturated conditions, the remarkable unifying rate behaviour across various experiments implied that the extraction of magnesium is more-or-less proportional to the bulk equilibrium concentration of protons. In addition, the associated term for activation energy with the rate law appeared negligible. At saturated conditions magnesium extraction was inhibited, which was attributed to precipitation of secondary phases in the porous substrate

Generic techno-economic optimization methodology for concurrent design and operation of solvent-based PCC processes

© 2020 Elsevier Ltd A techno-economic equation-based methodology is developed for optimal design and operation of integrated solvent-based post-combustion carbon capture (PCC) processes using a rate-based model for the interaction of gas and liquid. The algorithm considers a wide range of techno-economic design and operation parameters such as number of absorber/desorber columns, height of columns, diameter of columns, operating conditions (P, T) of columns, pressure drop, packing type, percentage of CO2 mitigated, captured CO2 purity, amount of solvent regeneration, flooding velocities of columns, and number of compression stages. A case study is conducted to showcase two common objective-functions i) minimizing total capital investment, and ii) minimizing levelized capture costs, both for a 300 MW coal-power plant in Australia. The former objective leads to the lowest possible total capital cost of $312.4 M corresponding to levelized carbon capture cost of 58.1$/tonne−CO2. For objective (ii), however, the lowest levelized carbon capture cost is found to be around ten percent lower (52.8 $/tonne−CO2), though it leads to a higher total capital cost ($325.2 M). The results indicate that the design and operation variables are markedly interactive, and no unique optimal design exists which can deliver all desired outcomes at once. Therefore, decisions on the selection of right variables become dependent on the decision-makers techno-economic objectives

Confirming vertical fetal infection with coronavirus disease 2019: Neonatal and pathology criteria for early onset and transplacental transmission of severe acute respiratory syndrome coronavirus 2 from infected pregnant mothers

Increasing numbers of pregnant women with coronavirus disease 2019 are being reported around the world. The majority of neonates delivered to pregnant women infected with severe acute respiratory syndrome coronavirus 2 have been negative for the virus, but a small number have tested positive for infection. It is important to determine whether vertical transmission of coronavirus disease 2019 occurs and the mechanisms for its development. Based on a number of clinical and laboratory findings, it has been suggested that transplacental transmission may be occurring, but a method to confirm this is necessary. This communication analyzes and evaluates the covariables that have been discussed as potential indicators of vertical and, specifically, intrauterine transmission, including the timing of onset of neonatal illness, neonatal viral test positivity, neonatal antibody testing for immunoglobulin (Ig) G and IgM, and viral analysis of swabs of whole specimens of placental tissue. None of these methods can provide confirmatory evidence that infection developed prior to labor and delivery, or that transplacental transmission occurred. This commentary proposes that diagnosis of early-onset neonatal coronavirus disease 2019 infection should be limited to neonates with positive reverse transcription polymerase chain reaction testing for severe acute respiratory syndrome coronavirus 2 within the initial 72 hours of life. It also proposes that the occurrence of intrauterine transplacental severe acute respiratory syndrome coronavirus 2 among infected mother-infant dyads be based upon identification of severe acute respiratory syndrome coronavirus 2 in chorionic villus cells using immunohistochemistry or nucleic acid methods such as in situ hybridization. Evaluating placentas from neonates with coronavirus disease 2019 using these methods will be instrumental in determining the potential role and prevalence of transplacental transmission of the coronavirus. © 2020 College of American Pathologists. All rights reserved

New insights into perinatal testicular torsion

Perinatal testicular torsion is a relatively rare event that remains unrecognized in many patients or is suspected and treated accordingly only after an avoidable loss of time. The authors report their own experience with several patients, some of them quite atypical but instructive. Missed bilateral torsion is an issue, as are partial torsion, possible antenatal signs, and late presentation. These data are discussed together with the existing literature and may help shed new light on the natural course of testicular torsion and its treatment. The most important conclusion is that a much higher index of suspicion based on clinical findings is needed for timely detection of perinatal torsion. It is the authors’ opinion that immediate surgery is mandatory not only in suspected bilateral torsions but also in cases of possible unilateral torsions. There is no place for a more fatalistic “wait-and-see” approach. Whenever possible, even necrotic testes should not be removed during surgery because some endocrine function may be retained

Comparative Analysis of Galtung’s Peace Theory And Baha’i Faith Peace Plan

Peace has always been a pivotal issue in the core of humankind’s thoughts throughout centuries; prophets, great thinkers, poets and elites have expressed their concern, vision and ideas of peace. Major world religions have teachings for peace. As one of the new religious movements of the world, Baha’i Faith has placed peace in the focus of its teaching. There have also been academic and intellectual efforts to define peace and to present plans for making peace like the works of Johan Galtung, the founder of the peace and conflict studies. The purpose of this study is to compare and contrast the peace plan of Baha’i Faith with Johan Galtung’s peace theory and explore their possible crucial differences and similarities (commonalities). In Galtung’s book, Peace by Peaceful Means: Peace and Conflict, Development and Civilization, the first chapter is peace theory which is used to explore Baha’i teachings on peace in Baha’i primary sources like writings of Bahá'u'lláh, the founder of Baha’i Faith, Abdu’l-Bahá' (first successor), Shoghi Effendi (Guardian and appointed head of the Faith) and Universal House of Justice (supreme ruling body) publications. Secondary Baha’i sources are also studied which are articles, papers and books written about Baha’i Faith. The method of comparative analysis used in this study is lens comparison in which we explore A (Galtung’s Peace Theory) less than B (Baha’i Faith peace plan), we use A as a lens through which to view B. The text A is used as a framework to understand and compare with text B. Galtung’s peace theory is an umbrella under which Baha’i teachings are studied. The idea of peace and the approach toward this idea is in the center of this comparison. During this process, the differences and commonalities of A and B are listed and analyzed in three realms, i.e. in relation to peace and gender, peace and democracy and peace and inter-state systems. After every point by point comparison chapter, all common and different features of A and B are observed, listed and analyzed to verify to what degree they are similar with or differ from each other. In this way, it is possible to see the level of proximity and remoteness of two sources and to verify how much they converge or diverge. The thesis reveals in which areas of peace-building ideas, Galtung and Baha’i Faith have common approaches and in which areas they have different standpoints, i.e. this paper disclosed, on gender and peace, both approaches have high level of proximity and convergence