Modeling desorption kinetics of a persistent organic pollutant from field aged sediment using a bi-disperse particle size distribution

Purpose With the predicted climate change, it is expected that the chances of river flooding increase. During flood events, sediments will resuspend and when sediments are polluted, contaminants can be transferred to the surrounding water. In this paper we discuss a numerical intraparticle diffusion model that simulates desorption of dieldrin from a suspension of contaminated porous sediment particles with a well-characterized particle size distribution. The objective of this study was to understand the desorption rate (flux) of dieldrin from a suspension of field-aged sediment at different hydraulic retention times (HRT) of the aqueous phase and to elaborate the effect of particle-size distribution on mass transfer. Materials and methods Desorption kinetics of dieldrin, a persistent organic pollutant (POP), were experimentally measured and described in a separate paper using field-contaminated sediment. A radial diffusion model, accommodating intraparticle reversible sorption kinetics, aqueous phase pore diffusion, and a sink term for bulk aqueous phase refreshment was used to describe the experimental data. Results and discussion We observed rapid equilibrium of contaminants between small particles (10 µm) and the surrounding water even though the sorption affinity of dieldrin towards organic matter was high. On the contrary, for the larger particles (84 µm), calculations show that desorption was limited by intraparticle diffusion. Combining small and larger particles in our radial diffusion model resulted in the biphasic desorption behavior often observed even when using a linear isotherm. Conclusions Flood events will result in an increase of desorption rate of POPs from sediments to the surrounding water. HRT and the particle-size distribution determine the desorption rate. We conclude that nonstationary diffusion within organic matter is the main process of mass transfer. Particle size distributions are very valuable to understand the phenomenology related to mass transfer limitations often described as limited bioavailability and can be used as basis to develop engineering options to limit contaminant mass fluxes into the environmen

Fiber propagation of vector modes

Here we employ both dynamic and geometric phase control of light to produce radially modulated vector-vortex modes, the natural modes of optical fibers. We then measure these modes using a vector modal decomposition set-up as well as a tomography measurement, the latter providing a degree of the non-separability of the vector states, akin to an entanglement measure for quantum states. We demonstrate the versatility of the approach by creating the natural modes of a step-index fiber, which are known to exhibit strong mode coupling, and measure the modal cross-talk and non-separability decay during propagation. Our approach will be useful in mode division multiplexing schemes for transport of classical and quantum states.Comment: 6 pages, 4 figures, 1 tabl

MANAGEMENT EFFECTS OF SPATIALLY DISPERSED LAND TRACTS: A SIMULATION ANALYSIS

A sequential simulation model is used to test a way to study the relationship between net farm income and land tract dispersion, total acres, machinery size and rainfall. The model simulates the day-to-day sequence of field work on a hypothetical farm simulation varying crop acreage, machinery size and for a wet and dry rainfall situation. Data generated by this model are then analyzed using a regression equation estimating the influence of studied variables on net farm income.Land Economics/Use,

Direct fiber excitation with a digitally controlled solid state laser source

Mode division multiplexing has been mooted as a future technology to address the impending data crunch of existing fiber networks. Present demonstrations delineate the light source from the mode creation steps, potentially inhibiting integrated solutions. Here we demonstrate an integrated mode generating source in the form of a digitally controlled solid state laser with an intra-cavity spatial light modulator. In our proof-of-principle experiment we create fiber modes on demand and couple them directly into a few-mode fiber, where after transmission they are decoupled by modal decomposition. This is the first demonstration of a single source for encoding information into the spatial modes of light

Effect of metabolic syndrome and aging on Ca2+ dysfunction in coronary smooth muscle and coronary artery disease severity in Ossabaw miniature swine

BACKGROUND: Metabolic syndrome (MetS) and aging are prevalent risk factors for coronary artery disease (CAD) and contribute to the etiology of CAD, including dysregulation of Ca2+ handling mechanisms in coronary smooth muscle (CSM). The current study tested the hypothesis that CAD severity and CSM Ca2+ dysregulation were different in MetS-induced CAD compared to aging-induced CAD. METHODS: Young (2.5 ± 0.2 years) and old (8.8 ± 1.2 years) Ossabaw miniature swine were fed an atherogenic diet for 11 months to induce MetS and were compared to lean age-matched controls. The metabolic profile was confirmed by body weight, plasma cholesterol and triglycerides, and intravenous glucose tolerance test. CAD was measured with intravascular ultrasound and histology. Intracellular Ca2+ ([Ca2+]i) was assessed with fura-2 imaging. RESULTS: CAD severity was similar between MetS young and lean old swine, with MetS old swine exhibiting the most severe CAD. Compared to CSM [Ca2+]i handling in lean young, the MetS young and lean old swine exhibited increased sarcoplasmic reticulum Ca2+ store release, increased Ca2+ influx through voltage-gated Ca2+ channels, and attenuated sarco-endoplasmic reticulum Ca2+ ATPase activity. MetS old and MetS young swine had similar Ca2+ dysregulation. CONCLUSIONS: Ca2+ dysregulation, mainly the SR Ca2+ store, in CSM is more pronounced in lean old swine, which is indicative of mild, proliferative CAD. MetS old and MetS young swine exhibit Ca2+ dysfunction that is typical of late, severe disease. The more advanced, complex plaques in MetS old swine suggest that the "aging milieu" potentiates effects of Ca2+ handling dysfunction in CAD

Suboccipital lateral injection of intrathecal chemotherapy in a patient with mantle cell lymphoma

Background: Even today patients who suffer from mantle cell lymphoma have a poor prognosis, especially when the CNS is involved. To confirm the diagnosis of meningeosis lymphomatosa, asservation of the liquor cerebrospinalis is necessary. During this procedure, intrathecal chemotherapy may be given if there is clinical evidence of meningeosis. If lumbar puncture cannot be performed, a lateral suboccipital puncture may be an alternative approach. Patient and Methods: We report the case of a 65-year-old patient who suffered from mantle cell lymphoma stage IV. The patient presented with symptoms of progressive paraparesis of both legs and incontinence, with tumor mass intradural from the 12th thoracic vertebra to the level of S1. During irradiation, the patient developed symptoms of diffuse meningiosis lymphomatosa. The conventional lumbar puncture was impossible, because of tumor present in the thoracico-lumbar junction. Results: A suboccipital puncture was performed for both collecting cerebrospinal fluid and application of chemotherapy ( cytosine arabinoside/dexamethasone). This lead to remarkable improvement of the patient's clinical symptoms. Conclusion: The suboccipital cervical puncture was performed without complications. A variation of the intrathecal approach is described, which may serve as alternative when conventional lumbar puncture is not possible

Machine Parameters and Projected Luminosity Performance of Proposed Future Colliders at CERN

In response to a request from the CERN Scientific Policy Committee (SPC), the machine parameters and expected luminosity performance for several proposed post-LHC collider projects at CERN are compiled: three types of hadron colliders (HL-LHC upgrade, FCC-hh and HE-LHC), a circular lepton collider (FCC-ee), a linear lepton collider (CLIC), and three options for lepton-hadron colliders (LHeC, HE-LHeC, and FCC-eh). Particular emphasis is put on availability, physics run time, and efficiency. The information contained in this document was presented at the SPC Meeting of September 2018. It will serve as one of the inputs to the 2019/20 Update of the European Strategy for Particle Physics