Reactivity of alkaline lignite fly ashes towards CO2 in water

The reaction kinetics between alkaline lignite fly ashes and CO2 (pCO2 = 0.01--0.03 MPa)were studied in a laboratory CO2 flow-through reactor at 25--75 degrees C. The reaction is characterized by three phases that can be separated according to the predominating buffering systems and the rates of CO2 uptake. Phase I (pH > 12, < 30 min) is characterized by the dissolution of lime, the onset of calcite precipitation and a maximum uptake, the rate of which seems to be limited by dissolution of CO2. Phase II (pH < 10.5, 10--60 min) is dominated by the carbonation reaction. CO2 uptake in phase III (pH < 8.3) is controlled by the dissolution of periclase (MgO) leading to the formation of dissolved magnesium-bicarbonate. Phase I could be significantly extended by increasing the solid-liquid ratios and temperature, respectively. At 75 degrees C the rate of calcite precipitation was doubled leading to the neutralization of approximately 0.23 kg CO2 per kg fly ash within 4.5 h, which corresponds to nearly 90% of the total acid neutralizing capacity.     

Influence of fast pyrolysis temperature on biochar labile fraction and short-term carbon loss in a loamy soil

Production of bio-oil, gas and biochar from pyrolysis of biomass is considered a promising technology for combined production of bioenergy and recalcitrant carbon (C) suitable for sequestration in soil. Using a fast pyrolysis centrifuge reactor (PCR) the present study investigated the relation between fast pyrolysis of wheat straw at different reactor temperatures and the short-term degradability of biochar in soil. After 115 days incubation 3-12% of the added biochar-C had been emitted as CO₂. On average, 90% of the total biochar-C loss occurred within the first 20 days of the experiment, emphasizing the importance of knowing the biochar labile fraction when evaluating a specific biochars C sequestration potential. The pyrolysis temperature influenced the outputs of biochar, bio-oil and syngas significantly, as well as the stability of the biochar produced. Contrary to slow pyrolysis a fast pyrolysis process may result in incomplete conversion of biomass due to limitations to heat transfer and kinetics. In our case chemical analysis of the biochars revealed unconverted cellulosic and hemicellulosic fractions, which in turn were found to be proportional with the short-term biochar degradation in soil. As these labile carbohydrates are rapidly mineralized, their presence lowers the biochar-C sequestration potential. By raising the pyrolysis temperature, biochar with none or low contents of these fractions can be produced, but this will be on the expense of the biochar quantity. The yield of CO₂ neutral bio-oil is the other factor to optimize when adjusting the pyrolysis temperature settings to give the overall greatest climate change mitigation effect.     

A stochastic model for the simulation of wind turbine blades in static stall

The aim of this work is to improve aeroelastic simulation codes by accounting for the unsteady aerodynamic forces that a blade experiences in static stall. A model based on a spectral representation of the aerodynamic lift force is defined. The drag and pitching moment are derived using a conditional simulation technique for stochastic processes. The input data for the model can be collected either from measurements or from numerical results from a Computational Fluid Dynamics code for airfoil sections at constant angles of attack. An analysis of such data is provided, which helps to determine the characteristics of stall. The model is applied to wind turbine rotor cases, including the stand still condition, and results are compared to experimental data. Copyright © 2009 John Wiley & Sons, Ltd.     

Time-Dependent Molecular Motifs of Pulmonary Fibrogenesis in COVID-19

(1) Background: In COVID-19 survivors there is an increased prevalence of pulmonary fibrosis of which the underlying molecular mechanisms are poorly understood; (2) Methods: In this multicentric study, n = 12 patients who succumbed to COVID-19 due to progressive respiratory failure were assigned to an early and late group (death within ≤7 and >7 days of hospitalization, respectively) and compared to n = 11 healthy controls; mRNA and protein expression as well as biological pathway analysis were performed to gain insights into the evolution of pulmonary fibrogenesis in COVID-19; (3) Results: Median duration of hospitalization until death was 3 (IQR25-75, 3–3.75) and 14 (12.5–14) days in the early and late group, respectively. Fifty-eight out of 770 analyzed genes showed a significantly altered expression signature in COVID-19 compared to controls in a time-dependent manner. The entire study group showed an increased expression of BST2 and IL1R1, independent of hospitalization time. In the early group there was increased activity of inflammation-related genes and pathways, while fibrosis-related genes (particularly PDGFRB) and pathways dominated in the late group; (4) Conclusions: After the first week of hospitalization, there is a shift from pro-inflammatory to fibrogenic activity in severe COVID-19. IL1R1 and PDGFRB may serve as potential therapeutic targets in future studies.     

Quantum dynamics of optical phonons generated by optical excitation of a quantum dot

The study of the fundamental properties of phonons is crucial to understand their role in applications in quantum information science, where the active use of phonons is currently highly debated. A genuine quantum phenomenon associated with the fluctuation properties of phonons is squeezing, which is achieved when the fluctuations of a certain variable drop below their respective vacuum values. We consider a semiconductor quantum dot (QD) in which the exciton is coupled to phonons. We review the fluctuation properties of the phonons, which are generated by optical manipulation of the QD, in the limiting case of ultra-short pulses. Then, we discuss the phonon properties for an excitation with finite pulses. Within a generating function formalism, we calculate the corresponding fluctuation properties of the phonons and show that phonon squeezing can be achieved by the optical manipulation of the QD exciton for certain conditions even for a single-pulse excitation where neither for short nor for long pulses squeezing occurs. To explain the occurrence of squeezing, we employ a Wigner function picture providing a detailed understanding of the induced quantum dynamics.     

Time course of PCDD/PCDF/PCB concentrations in breast-feeding mothers and their infants

PCDD/PCDF/PCB concentrations were measured in samples from four mothers (at delivery and during lactation) and their infants (at birth and the end of first year of life). For two of these mothers it was the second delivery and breast-feeding period, and additional data were available from first lactation period and the first-born infant at the age of 11 to 12 months. Five of the six infants were fully breast-fed for at least 17 weeks. In four of them a distinct PCDD/PCDF/PCB accumulation was observed at the end of the first year of life: concentrations in blood fat were 1.5 to 3.6 times higher than maternal levels measured at the same time. Due to decreasing maternal body burdens during lactation, PCDD/PCDF concentrations at 11 to 12 months of life were only about half as high in the second infant as in the first one at the same age. During second pregnancy, no important change of the concentrations was observed in maternal blood.     

Physiological responses to verbally inaccessible pictorial information in the left and right hemispheres.

The effects of brief pictorial information on transfer between the cerebral hemispheres were investigated through recordings of skin conductance responses. The stimuli had been judged previously as neutral, positive, or negative by an independent group of participants. The verbally accessible (VA) stimuli were neutral, whereas the brief, verbally inaccessible (VI) stimuli were positive or negative. The VA and VI stimuli were presented simultaneously, in the same visual half-field (intrahemispheric), or in the opposite visual half-field (interhemispheric). In a 3rd condition, there were only VA stimuli in either visual field. The right hemisphere was especially sensitive to negative VI presentations in both the inter- and intrahemispheric groups. The left hemisphere showed a corresponding sensitivity to positive stimuli, but only in the interhemispheric group. These findings confirm the hemispheric roles in mediating positive versus negative emotions and show that left-to-right transfer can take place without linguistic cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The kinetics of charges in dry bacteriorhodopsin Langmuir–Blodgett films—an analysis and comparison of electrical and optical signals

The decay of the M intermediate and the recovery kinetics of bacteriorhodopsin (bR) were detected optically in dry and wet bR Langmuir–Blodgett (LB) films and electrically in dry films. From the electrical signals the kinetics of the proton motion was distinguished from the cell function and it was found to be equal to that determined optically for the M intermediate decay. The rate-determining step for the recovery rate of bR was found to be the M state.     

Linear correlation-based learning models require a two-stage process for the development of orientation and ocular dominance

In our contribution we demonstrate, that orientation (OR) and ocular dominance (OD) cannot develop simultaneously in linear correlation-based learning (CBL) models, because OR and OD occupy separate domains in parameter space. We then analyse the conditions under which waves of spontaneous activity — as have been observed in the developing retina — may give rise at least to OR or OD. We find that in linear CBL models there must be subcortical convergence of ON/OFF as well as left eye/right eye pathways. We present a biologically plausible scenario in which the subcortical connectivity patterns resemble a competitive neural network and argue that OR and OD can robustly emerge, if a two-stage developmental process is assumed.