Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Asphaltenes constitute the heaviest, most polar and aromatic fraction of petroleum crucial to the formation of highlystable water-in-crude oil emulsions. The latter occur during crude oil production as well as spills and cause difficulties to efficient remediation practice. It is thought that in nanoaggregate form, asphaltenes create elastic layers around water droplets enhancing stability of the emulsion matrix. Ultrasonic characterisation is a high-resolution non-invasive tool in colloidal analysis shown to successfully identify asphaltene nanoaggregation in toluene. The high sensitivity of acoustic velocity to molecular rearrangements and ease in implementation renders it an attractive method to study asphaltene phase properties. Currently, aggregation is thought to correspond to an intersection of two concentration-ultrasonic velocity regressions. Our measurements indicate a variation in the proximity of nanoaggregation which is not accounted for by present models. We attribute this uncertainty to physico-chemical heterogeneity of the asphaltene fraction driven by variation in molecular size and propose a critical nanoaggregation region. We treated asphaltenes from North and South American crude oils with ruthenium ion catalysed oxidation to characterise their n-alkyl appendages attached to aromatic cores. Principal component analysis was performed to investigate the coupling between asphaltene structures and velocity measurements and their impact on aggregation

Role of the mesoamygdaloid dopamine projection in emotional learning

Amygdala dopamine is crucially involved in the acquisition of Pavlovian associations, as measured via conditioned approach to the location of the unconditioned stimulus (US). However, learning begins before skeletomotor output, so this study assessed whether amygdala dopamine is also involved in earlier 'emotional' learning. A variant of the conditioned reinforcement (CR) procedure was validated where training was restricted to curtail the development of selective conditioned approach to the US location, and effects of amygdala dopamine manipulations before training or later CR testing assessed. Experiment 1a presented a light paired (CS+ group) or unpaired (CS- group) with a US. There were 1, 2 or 10 sessions, 4 trials per session. Then, the US was removed, and two novel levers presented. One lever (CR+) presented the light, and lever pressing was recorded. Experiment 1b also included a tone stimulus. Experiment 2 applied intra-amygdala R(+) 7-OH-DPAT (10 nmol/1.0 A mu l/side) before two training sessions (Experiment 2a) or a CR session (Experiment 2b). For Experiments 1a and 1b, the CS+ group preferred the CR+ lever across all sessions. Conditioned alcove approach during 1 or 2 training sessions or associated CR tests was low and nonspecific. In Experiment 2a, R(+) 7-OH-DPAT before training greatly diminished lever pressing during a subsequent CR test, preferentially on the CR+ lever. For Experiment 2b, R(+) 7-OH-DPAT infusions before the CR test also reduced lever pressing. Manipulations of amygdala dopamine impact the earliest stage of learning in which emotional reactions may be most prevalent

Determination of Asphaltene Critical Nanoaggregate Concentration Region Using Ultrasound Velocity Measurements

Asphaltenes constitute the heaviest, most polar and aromatic fraction of petroleum crucial to the formation of highly-stable water-in-crude oil emulsions. The latter occur during crude oil production as well as spills and cause difficulties to efficient remediation practice. It is thought that in nanoaggregate form, asphaltenes create elastic layers around water droplets enhancing stability of the emulsion matrix. Ultrasonic characterisation is a high-resolution non-invasive tool in colloidal analysis shown to successfully identify asphaltene nanoaggregation in toluene. The high sensitivity of acoustic velocity to molecular rearrangements and ease in implementation renders it an attractive method to study asphaltene phase properties. Currently, aggregation is thought to correspond to an intersection of two concentration-ultrasonic velocity regressions. Our measurements indicate a variation in the proximity of nanoaggregation which is not accounted for by present models. We attribute this uncertainty to physico-chemical heterogeneity of the asphaltene fraction driven by variation in molecular size and propose a critical nanoaggregation region. We treated asphaltenes from North and South American crude oils with ruthenium ion catalysed oxidation to characterise their n-alkyl appendages attached to aromatic cores. Principal component analysis was performed to investigate the coupling between asphaltene structures and velocity measurements and their impact on aggregation

Evaluating year-to-year anomalies in tropical wetland methane emissions using satellite CH₄ observations

Natural wetlands are the largest source of methane emissions, contributing 20–40% of global emissions and dominating the inter-annual variability. Large uncertainties remain on their variability and response to climate change. This study uses atmospheric methane observations from the GOSAT satellite to evaluate methane wetland emission estimates. We assess how well simulations reproduce the observed methane inter-annual variability by evaluating the detrended seasonal cycle. The latitudinal means agree well but maximum differences in the tropics of 28.1–34.8 ppb suggest that all simulations fail to capture the extent of the tropical wetland seasonal cycle. We focus further analysis on the major natural wetlands in South America: the seasonally flooded savannah of the Pantanal (Brazil) and Llanos de Moxos (Bolivia) regions; and the riverine wetlands formed by the Paraná River (Argentina). We see large discrepancies between simulation and observation over the Pantanal and Llanos de Moxos region in 2010, 2011 and 2014 and over the Paraná River region in 2010 and 2014. We find highly consistent behaviour between the time and location of these methane anomalies and the change in wetland extent, driven by precipitation related to El Niño Southern Oscillation activity. We conclude that the inability of land surface models to increase wetland extent through overbank inundation is the primary cause of these observed discrepancies and can lead to under-estimation of methane fluxes by as much as 50% (5.3–11.8 Tg yr −1 ) of the observed emissions for the combined Pantanal and Paraná regions. As the hydrology of these regions is heavily linked to ENSO variability, being able to reproduce changes in wetland behaviour is important for successfully predicting their methane emissions

Compartmental Model for ²²³Ra-Dichloride in Patients With Metastatic Bone Disease From Castration-Resistant Prostate Cancer.

Purpose223Ra-Dichloride is used for treatment of patients with metastatic bone disease from castration-resistant prostate cancer. The uptake and mechanism of action of 223Ra-Dichloride is not well understood. The aim of this work was to develop a compartmental model for 223Ra-Dichloride in patients to improve understanding of the underlying mechanisms.Methods and materialsA compartmental model was developed based on activity retention data from 6 patients (2 treatments of 110 kBq/kg 223Ra-Dichloride) for plasma, bone surfaces, small intestines, large intestines, and excretion data. Rate constants were extracted. Rate constant variability between patients and treatments was assessed. A population model was proposed and compared with the established International Commission on Radiological Protection-67 compartmental model.ResultsA single bone compartment cannot accurately describe activity retention in the skeleton. The addition of a second bone compartment improved the fit to skeleton retention data, and the Akaike information criterion decreased. Mean rate constants of 4.0 (range, 1.9-10.9) and 0.15 (0.07-0.39) h-1 were obtained for transport from plasma to first bone compartment and vice versa. Rate constants from first to second bone compartment and back of 0.03 (0.02-0.06) and 0.008 (0.003-0.011) h-1 were calculated. Rate constants for individual patients showed no significant difference between patients and treatments.ConclusionsThe developed compartmental model suggests that 223Ra-Dichloride initially locates at the bone surface and is then incorporated into the bone matrix relatively quickly. This observation could have implications for dosimetry and understanding of the effects of alpha radiation on normal bone tissue. Results suggest that a population model based on patient measurements is feasible

Severe postpartum sepsis with prolonged myocardial dysfunction: a case report

<p>Abstract</p> <p>Introduction</p> <p>Severe sepsis during pregnancy or in the postpartum period is a rare clinical event. In non obstetric surviving patients, the cardiovascular changes seen in sepsis and septic shock are fully reversible five to ten days after their onset. We report a case of septic myocardial dysfunction lasting longer than ten days. To the best of our knowledge, this is the first report of prolonged septic myocardial dysfunction in a parturient.</p> <p>Case presentation</p> <p>A 24 year old Hispanic woman with no previous medical history developed pyelonephritis and severe sepsis with prolonged myocardial dysfunction after a normal spontaneous vaginal delivery.</p> <p>Conclusions</p> <p>Septic myocardial dysfunction may be prolonged in parturients requiring longer term follow up and pharmacologic treatment.</p

Purifying Selection in Deeply Conserved Human Enhancers Is More Consistent than in Coding Sequences

(c) 2014 De Silva et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

The five dimensions of B cell tolerance

B cell tolerance has been generally understood to be an acquired property of the immune system that governs antibody specificity in ways that avoid auto‐toxicity. As useful as this understanding has proved, it fails to fully explain the existence of auto‐reactive specificities in healthy individuals and contribution these may have to health. Mechanisms underlying B cell tolerance are considered to select a clonal repertoire that generates a collection of antibodies that do not bind self, ie tolerance operates more or less in three dimensions that largely spare autologous cells and antigens. Yet, most B lymphocytes in humans and probably in other vertebrates are auto‐reactive and absence of these auto‐reactive B cells is associated with disease. We suggest that auto‐reactivity can be embodied by extending the concept of tolerance by two further dimensions, one of time and circumstance and one that allows healthy cells to actively resist injury. In this novel concept, macromolecular recognition by the B cell receptor leading to deletion, anergy, receptor editing or B cell activation is extended by taking account of the time of development of normal immune responses (4th dimension) and the accommodation (or tolerance) of normal cells to bound antibody, activation of complement, and interaction with inflammatory cells (fifth dimension). We discuss how these dimensions contribute to understanding B cell biology in health or disease.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153034/1/imr12813.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153034/2/imr12813_am.pd