Per- and polyfluoroalkyl substances (PFAS) in river discharge: Modeling loads upstream and downstream of a PFAS manufacturing plant in the Cape Fear watershed, North Carolina.

The Cape Fear River is an important source of drinking water in North Carolina, and many drinking water intakes in the watershed are affected by per- and polyfluoroalkyl substances (PFAS). We quantified PFAS concentrations and loads in river water upstream and downstream of a PFAS manufacturing plant that has been producing PFAS since 1980. River samples collected from September 2018 to February 2021 were analyzed for 13 PFAS at the upstream station and 43-57 PFAS downstream near Wilmington. Frequent PFAS sampling (daily to weekly) was conducted close to gauging stations (critical to load estimation), and near major drinking water intakes (relevant to human exposure). Perfluoroalkyl acids dominated upstream while fluoroethers associated with the plant made up about 47% on average of the detected PFAS downstream. Near Wilmington, Σ43PFAS concentration averaged 143 ng/L (range 40-377) and Σ43PFAS load averaged 3440 g/day (range 459-17,300), with 17-88% originating from the PFAS plant. LOADEST was a useful tool in quantifying individual and total quantified PFAS loads downstream, however, its use was limited at the upstream station where PFAS levels in the river were affected by variable inputs from a wastewater treatment plant. Long-term monitoring of PFAS concentrations is warranted, especially at the downstream station. Results suggest a slight downward trend in PFAS levels downstream, as indicated by a decrease in flow-weighted mean concentrations and the best-fitting LOADEST model. However, despite the cessation of PFAS process wastewater discharge from the plant in November 2017, and the phase-out of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in North America, both fluoroethers and legacy PFAS continue to reach the river in significant quantities, reflecting groundwater discharge to the river and other continuing inputs. Persistence of PFAS in surface water and drinking water supplies suggests that up to 1.5 million people in the Cape Fear watershed might be exposed.

Enzymatically prepared n-alkyl esters of glucuronic acid: the effect of freeze-drying conditions and hydrophobic chain length on thermal behavior.

In this work, some of the physicochemical properties of enzymatically prepared n-alkyl esters of glucuronic acid are presented. Two questions are addressed. The first concerns the influence of post-purification freeze-drying conditions on octyl glucuronate thermotropic behavior. Depending on the amount of water added before freeze-drying, the alpha/beta anomeric ratio determined by (1)H NMR is affected and differences are observed in DSC thermograms probably due to polymorphism. The second question concerns the effect of hydrophobic chain length on the thermal behavior. An increase of both transition temperature and transition enthalpy is observed by increasing the number of carbon atoms in the alkyl chain (C8

Determination of elastomeric foam parameters for simulations of complex loading.

BACKGROUND: Finite element (FE) analysis has shown promise for the evaluation of elastomeric foam personal protection devices. Although appropriate representation of foam materials is necessary in order to obtain realistic simulation results, material definitions used in the literature vary widely and often fail to account for the multi-mode loading experienced by these devices. This study aims to provide a library of elastomeric foam material parameters that can be used in FE simulations of complex loading scenarios. METHOD OF APPROACH: Twelve foam materials used in footwear were tested in uni-axial compression, simple shear and volumetric compression. For each material, parameters for a common compressible hyperelastic material model used in FE analysis were determined using: (a) compression; (b) compression and shear data; and (c) data from all three tests. RESULTS: Material parameters and Drucker stability limits for the best fits are provided with their associated errors. The material model was able to reproduce deformation modes for which data was provided during parameter determination but was unable to predict behavior in other deformation modes. CONCLUSIONS: Simulation results were found to be highly dependent on the extent of the test data used to determine the parameters in the material definition. This finding calls into question the many published results of simulations of complex loading that use foam material parameters obtained from a single mode of testing. The library of foam parameters developed here presents associated errors in three deformation modes that should provide for a more informed selection of material parameters.

Microbial degradation of cellulose wastes in continuous bioreactors.

This paper reports on experiments concerning the biodegradation of cellulose wastes from wine-producing industries, as well as from cereal crops processing in agricultural farms, using cellulolytic bacterial and fungal species immobilized on radiopolymerized hydrogels. There are described three types of such bioreactors and their main features. The immobilization procedures have been achieved using the following species of microorganisms: Bacillus subtilis and B. licheniformis, from bacteria, as well as Pleurotus ostreatus and Trichoderma viride, from filamentous fungi. The immobilization matrices were prepared by radiopolymerization, using a 60Co radioactive source, designed for gamma irradiation. A consistent increasing of dry weight loss correlated with a correspondent enhancement of biodegradation rate by 10 - 20%, have revealed significant differences of metabolic activities between these immobilized bacteria and fungi on radiopolymerized hydrogels and those free cells cultures of the same microorganisms, which were grown on agar-agar gels and used as control references, in all performed experiments. Regarding the enzymatic activity of immobilized microorganisms the registered results have revealed an increasing of total reducing sugars with 20 - 30 mg g(-1). The enhancement of cellulolytic activity was higher with 0.1 - 0.3 U min(-1), in comparison with those values determined for the same process performed by the same microorganisms, used as control.

Osteosynthesis of fractures of the femur with flexible metallic intramedullary nails.

The authors discuss their use of Ender's method in the treatment of fractures of the femur. The diameter and length of the nails depends on the type of fracture. 1) Three nails of 4 mm diameter are introduced in parallel from the medial condyle in fractures of the femoral neck; 2) 5 mm nails are used, in similar fashion, for the fixation of intertrochanteric and subtrochanteric fractures; 3) 5 mm nails are used for diaphyseal, supracondylar and intercondylar fractures, introduced in crossed fashion ("Eiffel Tower" technique) from both medial and lateral condyles. This method of fixation has proved to be extremely stable. The operation itself is quick, with no blood loss or shock. The patient can resume partial weight bearing after a week in stabilised intertrochanteric and shaft fractures, after a month in less stable types, and after three to four months in fractures of the neck of the femur. This report is based on the first 250 cases treated by this method.