ABSTRACT. The micronucleus (MN) assay evaluates the effects of low doses of genotoxic carcinogens and can detect structural lesions that survive mitotic cycles. The objective of this study was to determine both the genotoxicity of nickel (Ni) in buccal epithelial cells and the urinary excretion of Ni in children with metal crowns. This was a prospective longitudinal study based on 37 patients selected at the Facultad de Odontología de la Universidad Autónoma de Coahuila. MN assays were performed using buccal cells from the 37 patients, and Ni levels were determined from urine samples using inductively coupled plasma mass spectrometry at 1 (basal value), 15, and 45 days following the placement of crowns in each patient. Ni urinary excretion levels increased from 2.12 ± 1.23 to 3.86 ± 2.96 mg Ni/g creatinine (P < 0.05) and the frequency of exposed micronuclei increased from 4.67 ± 0.15 to 6.78 ± 0.167/1000 cells (P < 0.05) between 1 and 45 days post-crown placement. These
Thin film composite (TFC) membranes
of the prototypical polymer
of intrinsic microporosity (PIM-1) have been prepared by dip-coating
on a highly porous electrospun polyvinylidene fluoride (PVDF) nanofibrous
support. Prior to coating, the support was impregnated in a non-solvent
to avoid the penetration of PIM-1 inside the PVDF network. Different
non-solvents were considered and the results were compared with those
of the dry support. When applied for the separation of n-butanol/water mixtures by pervaporation (PV), the developed membranes
exhibited very high permeate fluxes, in the range of 16.1–35.4
kg m–2 h–1, with an acceptable n-butanol/water separation factor of about 8. The PV separation
index (PSI) of the prepared membranes is around 115, which is among
the highest PSI values that have been reported so far. Hybrid PV-distillation
systems have been designed and modeled in Aspen HYSYS using Aspen
Custom Modeler for setting up the PIM-1 TFC and commercial PDMS membranes
as a benchmark. The butanol recovery cost for the hybrid systems is
compared with a conventional stand-alone distillation process used
for n-butanol/water separation, and a 10% reduction
in recovery cost was obtained.
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