Non‐linear internal waves (NLIW) are important to processes such as heat transfer, nutrient replenishment and sediment transport on continental shelves. Our unique field observations of shoaling NLIW ...of elevation revealed a variety of different wave shapes, varying from relatively symmetric waves, to waves with either steepened leading‐ or trailing‐faces; many had evidence of trapped cores. The wave shape was related to the position of maximum density overturns and diapycnal mixing. We observed both shear (where sheared currents overcome the stabilizing effects of stratification) and convective (where the local velocity exceeds the wave propagation speed) instabilities. The elevated diapycnal mixing (>10−3 m2s−1) and heat flux (>500 Wm−2) were predominantly local to the NLIW of elevation packets, and were transported onshore 10s kilometers with the wave packets. We demonstrate that wave steepness may be a useful bulk property for the parameterization of wave‐averaged diapycnal heat flux.
Plain Language Summary
Predicting the distribution of constituents such as nutrients, heat, sediment and pollutants on the continental shelf is key to processes such as: the safe operation of offshore infrastructure; understanding the variation in primary productivity; the prediction of marine heat waves; and environmental impact assessments of new activities. Non‐linear internal waves, waves that travel within the stratified water column, are likely to have a significant impact on constituent transport; however, they are poorly understood. Here we present unique observations that quantify the properties of a class of these nonlinear internal waves, known as waves of elevation. These waves can break in a similar way to surface waves at the beach, leading to dramatic increases in turbulent mixing over horizontal length scales of 10s kilometers. We have used our observations to define the amount of vertical heat transport induced by the breaking waves as a function of wave steepness. The vertical heat transport can be used as a proxy to estimate the vertical nutrient transport. This study has made a step change in quantifying the impact of NLIW of elevation on vertical transport.
Key Points
Nonlinear internal waves of elevation can form both convective and shear instabilities, resulting in enhanced diapycnal mixing and heat flux
Breaking continues as the nonlinear waves propagate onshore, influencing diapycnal mixing and vertical heat flux over 10s of kilometers
The elevated heat flux associated with the nonlinear internal waves of elevation increases with the wave steepness
Abstract Modern treatment strategies have led to improvements in cancer survival, however these gains may be offset by the potential negative impact of cancer therapy on cardiovascular health. ...Cardiotoxicity is now recognized as a leading cause of long-term morbidity and mortality among cancer survivors. This Guideline, authored by a pan-Canadian expert group of healthcare providers and commissioned by the Canadian Cardiovascular Society (CCS), is intended to guide the care of cancer patients with established cardiovascular disease or those at risk of experiencing toxicities related to cancer treatment. It includes recommendations and important management considerations focusing on four main areas: identifying the high-risk population for cardiotoxicity; detection and prevention of cardiotoxicity; treatment of cardiotoxicity and a multidisciplinary approach to Cardio-oncology. All recommendations align with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Key recommendations for which the panel provides a strong level of evidence include: (1) routine evaluation of traditional cardiovascular risk factors and optimal treatment of pre-existing cardiovascular disease be performed in all patients prior to, during and after receiving cancer therapy, (2) initiation, maintenance and/or augmentation of anti-hypertensive therapy be instituted per CHEP Guidelines for patients with pre-existing hypertension or for those experiencing hypertension related to cancer therapy and (3) investigation and management follow current CCS Heart Failure (HF) Guidelines for cancer patients who develop clinical HF or an asymptomatic decline in left ventricular ejection fraction during or after cancer treatment. This Guideline provides guidance to clinicians on contemporary best practices for the cardiovascular care of cancer patients.
This research aims to provide insight into the structure and reaction mechanism of silica-rich phases formed as byproducts in direct aqueous carbonation of heat-activated lizardite. In undertaking ...this work, we employed analytical techniques such as thermogravimetric analysis (TGA), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), 29Si solid-state nuclear magnetic resonance (29Si SS NMR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to characterize carbonation products and to understand the mechanism of formation and the structure of silica-rich byproducts. Thermodynamic analysis predicts the formation of magnesite and amorphous silica in the process of direct aqueous carbonation of heat-activated lizardite under the experimental conditions studied. Characterization of carbonation products disclosed the presence of magnesite, amorphous silica, and magnesium silicate phases. Analysis of supernatant solutions obtained from direct aqueous carbonation by MALDI spectroscopy showed the presence of silica polymers, which precipitate during the carbonation experiments. The precipitated amorphous silica on the surface of reacting particles was found to subsequently adsorb the dissolved magnesium (Mg) from the solution to form a magnesium silicate phase.
•Side reactions produced serpentine and magnesium silicate hydroxide phases.•Extent of side reactions were elevated when experiments performed under nitrogen.•Side reactions reduced the magnesite ...yield by up to 40%.•Side reactions reduced the efficiency of direct aqueous carbonation process.
This work discloses a possible explanation for the relatively low efficiency and yield observed in direct aqueous carbonation of heat activated serpentine which remained a critical unanswered question during three decades of ex-situ mineral carbonation research and development. The discovery of undesirable side reactions, occurring during direct aqueous carbonation of heat activated serpentine has been reported and investigated in detail. These reactions result in the reformation of crystalline serpentine and precipitation of amorphous magnesium silicate hydroxide phase/s on the surface of reacting feed particles. Reformation of serpentine occurs under relatively mild conditions (in terms of pressure and temperature) and after only a few minutes of reaction which is in stark contrast to the conditions and rates which occur during geological serpentinisation and other laboratory studies. Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy analyses showed precipitation of amorphous magnesium silicate hydroxide phase/s during carbonation process. Fourier Transform Infrared Spectroscopy and Thermogravimetric analyses identified and quantified free and hydrogen bonded hydroxyls of silanol groups in the structure of the reaction products when heat activated lizardite and antigorite were carbonated. The growth of a crystalline serpentine phase was confirmed and quantified by X-ray Diffraction and Thermogravimetric analyses in the reaction products when heat activated antigorite was used a feed.
Osteoarthritis (OA) is one of the most common musculoskeletal diseases. OA is characterized by degeneration of the articular cartilage as well as the underlying subchondral bone. Post-traumatic ...osteoarthritis (PTOA) is a subset of OA caused by mechanical trauma. Mouse models, such as destabilization of the medial meniscus (DMM), are useful to study PTOA.
micro-Computed Tomography (microCT) imaging is the predominant technique used to scan the mouse knee in OA studies. Nevertheless,
microCT enables the longitudinal assessment of bone microstructure, reducing measurement variability and number of animals required. The effect of image resolution in measuring subchondral bone parameters was previously evaluated only for a limited number of parameters. The aim of this study was to evaluate the ability of
microCT imaging in measuring the microstructural properties of the mouse tibia trabecular and cortical subchondral bone, with respect to
high resolution imaging, in a DMM model of PTOA. Sixteen male C57BL/6J mice received DMM surgery or sham operation at 14 weeks of age (N=8 per group). The right knee of each mouse was microCT scanned
(10.4μm voxel size) and
(4.35μm voxel size) at the age of 26 weeks. Each image was aligned to a reference image using rigid registration. The subchondral cortical bone plate thickness was measured at the lateral and medial condyles. Standard morphometric parameters were measured in the subchondral trabecular bone.
microCT imaging led to significant underestimation of bone volume fraction (-14%), bone surface density (-3%) and trabecular number (-16%), whereas trabecular thickness (+3%) and separation (+5%) were significantly overestimated. Nevertheless, most trabecular parameters measured
were well correlated with
measurements (R
0.69-0.81). Degree of anisotropy, structure model index and connectivity density were measured
with lower accuracy. Excellent accuracy was found for cortical thickness measurements. In conclusion, this study identified what bone morphological parameters can be reliably measured by
microCT imaging of the subchondral bone in the mouse tibia. It highlights that this approach can be used to study longitudinal effects of diseases and treatments on the subchondral cortical bone and on most subchondral trabecular bone parameters, but systematic over- or under-estimations should be considered when interpreting the results.
Utilising the byproducts of mineral carbonation processes contributes to rendering the technology environmentally benign and enhances the economically viability of the process. In this work we ...synthesised, characterised and investigated the technical feasibility and environmental benefits of utilising feed and byproducts of mineral carbonation technology as Portland cement substitutes. These materials, with and without pre-treatment, were used to substitute 5, 10 and 20 wt% of Portland cement in mortars. Pozzolanic activity tests indicated that acid treated silica enriched residue (ATSER) displayed pozzolanic activity. At 5% cement replacement all materials showed compressive strengths comparable to the control. When 10 wt% of cement was replaced, only heat activated lizardite showed strength results similar to the control. The compressive strength of mortars containing other samples with 10 wt% or greater cement replacement showed that the extra water demand outweighed any pozzolanic contribution of mineral carbonation materials and resulted in a lowering of the compressive strength of these mortars compared to controls, in particular when in excess of 10 wt% of cement is replaced. An environmental analysis showed that in addition to significant CO2 emissions reduction, the economic and environmental costs of waste disposal were avoided when mineral carbonation byproducts substituted Portland cement.
•Results of Si extraction at pH∼13.5 indicated ATSER had the fastest rate of Si extraction even higher than silica fume.•Pozzolanic activity tests showed that ATSER displayed some level of pozzolanic activity slightly less than silica fume.•5 wt% cement replacement with mineral carbonation materials showed acceptable compressive strength for all subsitutes.•10 wt% or higher cement replacement resulted in lower strength compared to the control.
Chronic urticaria and hormones: Is there a link? Amsler, E.; Augey, F.; Soria, A. ...
Journal of the European Academy of Dermatology and Venereology,
09/2016, Letnik:
30, Številka:
9
Journal Article
Recenzirano
Background
While the role of oestrogens in bradykinin angioedema (AE) has been clearly demonstrated, scarce data are available about the role of sex hormones in chronic urticaria (CU).
Objectives
To ...gather information from a population of women with various forms of CU chronic spontaneous urticaria (CSU), including a subtype of isolated histaminic AE and a classic subtype of association of wheals and AE, and exclusive inducible urticaria (IU) about the impact of sex hormones and reproductive factors on their symptoms.
Methods
This was a cross‐sectional study comprising interviews of 200 women consulting for CU at nine centres throughout France between May and July 2013. The dermatologists filled in an online questionnaire on the impact of reproductive factors (puberty, contraception and pregnancy) and hormonal treatments on the course of CU, including CSU and IU, in the presence of the women.
Results
Most of the women did not experience CU before puberty and if so, puberty did not influence the course of CU. Only 16 women had experienced a pregnancy during CU which caused a worsening of symptoms in four. Hormonal contraception was associated with aggravation in a minority of women, mostly women with CSU (10%). Women with isolated histaminic AE did not exhibit any female sex hormone dependency.
Conclusions
It would appear that sex hormones act as a trigger in only a small subset of women with CU. Nevertheless, this should be taken into account to improve patient management.
Vast reserves of peridotite and serpentinite rocks can be utilised for the safe and permanent sequestration of global CO2 emissions via aqueous mineral carbonation. These, and indeed most feedstocks ...used in mineral carbonation require ultrafine grinding and/or heat-activation, to engender significantly enhanced reactivity in the rock such that it can then be carbonated. Both activation processes are energy intensive and present significant obstacles to the commercial application of mineral carbonation. Here we show that these limitations can be addressed, at least in part, through the application of a concurrent or in operando grinding technique which does not require feedstocks which have been subjected to prior ultrafine grinding nor heat-activation.
Concurrent grinding is shown to result in a significant increase in magnesite yields for non-heat activated feedstock, prepared such that fines (<20 μm particles) were excluded from the feed. We assert that concurrent grinding may be a suitable technique for the processing of feedstocks such as those containing significant proportions of forsterite and pyroxene, minerals which are unresponsive to thermal activation for use in aqueous mineral carbonation. This study also investigates the effect of different grinding media particle size on reducing the particle size distribution (PSD) of the feed. Optimum ratio of grinding media size to feed particle size, optimum grinding media and slurry concentrations, optimum time for grinding and optimum impeller designs are determined for the system under study. The quantitative effect of grinding media concentration, slurry concentration, pressure and temperature on magnesite yield has been investigated.
•Feedstocks can be carbonated using concurrent grinding without prior pre-treatment.•Different grinding medias and media mixtures were investigated.•Different impeller designs were investigated.•Quantitative effect of operating variables was determined.•62% magnesite yield was obtained using raw dunite rock.
•The dissolution kinetics of roasted lizardite at different T and pH were studied.•An initial rapid liberation of Mg2+ followed by a very slow extraction was observed.•Increasing temperature caused ...an increase in the rate of Mg extraction initially.•The extent of extraction of Mg2+ decreased due to precipitation of silica.•Silica re-precipitation at high temperature and S/L was demonstrated.
The dissolution of magnesium silicate minerals such as serpentine in aqueous solutions saturated or near saturated with carbon dioxide (CO2) enables its subsequent reaction to form magnesium carbonate, a process called aqueous mineral carbonation. The dissolution rate of magnesium ions (Mg2+) from thermally activated serpentine and the factors influencing the rate and extent of dissolution have been studied in our research group. The current contribution focuses on the effect of temperature and pH on the dissolution of heat activated lizardite (a polymorph of serpentine). The extent of dissolution of thermally activated lizardite was measured experimentally as a function of temperature (25 °C ≤ T ≤ 75 °C) and pH (1.2 ≤ pH ≤ 9.8). It was found that at higher temperatures the level of Mg extraction is greater during the initial stage of dissolution but is then hindered by the re-precipitation of amorphous silica. Thermodynamic modelling was used to assess the susceptibility of solid phase formation and confirmed the likelihood of re-precipitation of amorphous silica from the solutions. For the first time, in this work, the crackling core model (CCM) was used to model experimental data at different pH values.
PDF
