77 research outputs found
Probability of Heavy Metals Mobility from Dumped Sediments in a Quarry
The former Texcoco Lake was dreg to build the new international Mexico City airport were pumped in a quarry. The dredged sediments could have heavy metals (HMs) capable to pollute water bodies. The study aimed to evaluate the content of Cu, Zn, Cd, Ni, and Pb of the sediments deposited in the quarry, its transfer to the runoff water and the Cu, Zn, Ni, and Pb adsorption in the subsoil. We measured water infiltration rate, HMs concentration in sediments, water runoff, and the HM adsorption in the subsoil. The infiltration rate in sediments is low (? 10-7 cm/h). HMs in sediments are within the maximum permissible limits by the Mexican regulations, for sewage sludge. The HM in the runoff from the sediments are in the range of the Mexican regulations for the discharge into rivers and for irrigation purposes of agricultural soils. It is also within safe limits for irrigation use considered by FAO and EPA. The materials adsorption capacity of Pb (1250 mg kg-1), Zn (588 mg kg-1), and Cu (1250 mg kg-1) is higher than the concentration of metals in the runoff water, so it is unlikely the movement of HM down the subsoil.Dregs from the former Texcoco Lake were used to build the new international Mexico City airport and pumped in a quarry. The dredged sediments could have heavy metals (HMs) capable of polluting water bodies. The studyâs objective was to evaluate the content of Cu, Zn, Cd, Ni, and Pb of the sediments deposited in the quarry, their transfer to the runoff water and the adsorption of Cu, Zn, Ni, and Pb in the subsoil. Other variables measured were water infiltration rate, HM in sediments, water runoff, and the HM adsorption in the subsoil. The infiltration rate in sediments is low (†10-7 cm/h). HMs in sediments are within the maximum permissible limits by Mexican regulations, for sewage sludge. The HMs in the runoff from the sediments are in the range of the Mexican regulations for the discharge into rivers and for irrigation purposes of agricultural soils. They are also within safe limits for irrigation use considered by FAO and EPA. The materials adsorption capacity of Pb (1250 mg kg-1), Zn (588 mg kg-1), and Cu (1250 mg kg-1) is higher than the concentration of metals in the runoff water, so the movement of HMs down into the subsoil is unlikely.
Charge Fluctuations on Membrane Surfaces in Water
We generalize the predictions for attractions between over-all neutral
surfaces induced by charge fluctuations/correlations to non-uniform systems
that include dielectric discontinuities, as is the case for mixed charged lipid
membranes in an aqueous solution. We show that the induced interactions depend
in a non-trivial way on the dielectric constants of membrane and water and show
different scaling with distance depending on these properties. The generality
of the calculations also allows us to predict under which dielectric conditions
the interaction will change sign and become repulsive
The Effect of Intra-Abdominal Hypertension Incorporating Severe Acute Pancreatitis in a Porcine Model
Introduction: Abdominal compartment syndrome (ACS) and intra abdominal hypertension(IAH) are common clinical findings in patients with severe acute pancreatitis(SAP). It is thought that an increased intra abdominal pressure(IAP) is associated with poor prognosis in SAP patients. But the detailed effect of IAH/ACS on different organ system is not clear. The aim of this study was to assess the effect of SAP combined with IAH on hemodynamics, systemic oxygenation, and organ damage in a 12 h lasting porcine model
Atypical ductal hyperplasia is a multipotent precursor of breast carcinoma
The current model for breast cancer progression proposes independent âlowâgrade (LG) likeâ and âhighâgrade (HG) likeâ pathways but lacks a known precursor to HG cancer. We applied low coverage whole genome sequencing to atypical ductal hyperplasia (ADH) with and without carcinoma to shed light on breast cancer progression. 14/20 isolated ADH cases harboured at least one copy number alteration (CNA), but had fewer aberrations than LG or HG ductal carcinoma in situ (DCIS). ADH carried more HGâlike CNA than LG DCIS (eg. 8q gain). Correspondingly, 64% (7/11) of ADH cases with synchronous HG carcinoma were clonally related, similar to LG carcinoma (67%, 6/9). This study represents a significant shift in our understanding of breast cancer progression, with ADH as a common precursor lesion to the independent âlowâgrade likeâ and âhighâgrade likeâ pathways. These data suggest that ADH can be a precursor of HG breast cancer and that LG and HG carcinomas can evolve from a similar ancestor lesion. We propose that although LG DCIS may be committed to a LG molecular pathway, ADH may remain multipotent, progressing to either LG or HG carcinoma. This multipotent nature suggests that some ADH could be more clinically significant than LG DCIS, requiring biomarkers for personalising management
Re-entrant DNA gels
DNA is acquiring a primary role in material development, self-assembling by design into complex supramolecular aggregates, the building block of a new-materials world. Using DNA nanoconstructs to translate sophisticated theoretical intuitions into experimental realizations by closely matching idealized models of colloidal particles is a much less explored avenue. Here we experimentally show that an appropriate selection of competing interactions enciphered in multiple DNA sequences results into the successful design of a one-pot DNA hydrogel that melts both on heating and on cooling. The relaxation time, measured by light scattering, slows down dramatically in a limited window of temperatures. The phase diagram displays a peculiar re-entrant shape, the hallmark of the competition between different bonding patterns. Our study shows that it is possible to rationally design biocompatible bulk materials with unconventional phase diagrams and tuneable properties by encoding into DNA sequences both the particle shape and the physics of the collective response
Scaling laws for microemulsions governed by spontaneous curvature
We introduce a model for microemulsions whose basic building blocks are cylindrical tubes connected by spherical junctions forming a network. The model predicts analytic scaling laws which quantitatively reproduce several prominent experimental features of the phase diagram, including the closed loops of 2-phase coexistence and the 3-phase body. The interfacial nature of our model, which takes into account only the curvature energy and the entropy of the interface, explains the observed water/oil symmetry and the collapse of the experimental data onto a single universal scaling curve
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