Exposure assessment and risk characterization for perfluorooctanoate in selected consumer articles

An exposure assessment and risk characterization was conducted to better understand the potential human health significance of trace levels of perfluorooctanoate (PFO) detected in certain consumer articles. PFO is the anion of perfluorooctanoic acid (PFOA). Concentrations of PFO in the consumer articles were determined from extraction tests and product formulation information. Potential exposures during consumer use of the articles were quantified based on an assessment of behavior patterns and regulatory guidance. Health benchmarks were developed and then compared to the exposure estimates to yield margins of exposure (MOEs). A simple one-compartment model was also developed to estimate contributions of potential consumer exposures to PFO concentrations in serum. While there are considerable uncertainties in this assessment, it indicates that exposures to PFO during consumer use of the articles evaluated in this study are not expected to cause adverse human health effects in infants, children, adolescents, adult residents, or professionals nor result in quantifiable levels of PFO in human serum.     

Up to 21 Different Sulfur-Heterocyclic Fatty Acids in Rapeseed and Mustard Oil

Three sulfur-heterocyclic fatty acids (SHFA) had been tentatively identified in rapeseed oil in the late 1980s. In this study we aimed to enrich and verify the presence of potential SHFA in one sample of native rapeseed oil, refined rapeseed oil and mustard seed oil. Fifty-gram samples of the three oils were individually saponified and converted into methyl esters. The resulting samples were hydrogenated and subjected three times to urea complexation. The resulting extracts of native rapeseed oil and mustard oil contained 21 different SHFA with 18, 20, 22 or 24 carbons. The refined rapeseed oil contained only nine C₁₈-SHFA. Structure investigation of the SHFA was performed by gas chromatography with mass spectrometry (GC/MS) using methyl esters and also 3-pyridylcarbinol esters. A direct screening of non-enriched samples by GC/MS in the selected ion monitoring mode and by GC with flame photometric detector (sulfur-selective) verified that the SHFA were native compounds of the oils and no artefacts of the sample preparation. Similar abundances of the four isomer groups of SHFA with monoenoic fatty acids of the same carbon number in these and five further rapeseed and mustard samples indicated that these could be the precursors of the SHFA.     

Hydrogen trapping: Synergetic effects of inorganic additives with cobalt sulfide absorbers and reactivity of cobalt polysulfide

The biphasic product CoS₂ + Co(OH)₂ obtained by oxidation of cobalt sulfide is known to trap hydrogen at room temperature and low pressure according to a balanced reduction equation. Adding various inorganic compounds to this original absorber induces their reduction by hydrogen in the same conditions at a significant rate: (i) excess cobalt hydroxide is reduced to metallic cobalt; (ii) nitrate ions are reduced to ammonia; (iii) sulfur and sodium thiosulfate are reduced to H₂S or NaHS and Na₂S, respectively. Without a hydrogen absorber these inorganic compounds are not reduced by H₂, suggesting synergetic effects involving H₂ and the hydrogen absorber. Amorphous cobalt polysulfide, CoS₅, is also reduced by hydrogen at room temperature and releases H₂S gas. In the presence of a base to neutralize H₂S gas, the reaction rate is initially slower than with the CoS₂ + Co(OH)₂ mixture due to the higher stability of polysulfide chains but the H₂ trapping yield is improved, making CoS₅ a good candidate for H₂ trapping.     

Positive Effect of Periodic Micropatterns on Compression Ring Friction

Internal combustion engines are increasingly regulated in regard to efficiency and environmental impact, which requires advanced optimization strategies of engine components. The contact between the top ring and the cylinder liner is critical to the efficiency of an internal combustion engine. As shown in a previous study, an amorphous carbon coating can greatly improve the friction properties of piston rings. This work expands on these results by fabricating laser-interference-induced microchannels on the coating perpendicular to the direction of movement with a mean depth of 0.97 and 3.13 μm spatial period to further optimize the tribology. Fired single-cylinder engine measurements of the microtextured rings show a significant reduction in mean piston assembly friction of 5% for operation points that are relevant for urban transportation and up to 10% for specific operation points. Subsequent multibody elastohydrodynamic simulations prove that measured friction changes result from the compression ring microtexture. In particular, the microtexture increases the hydrodynamic pressure, reduces hydrodynamic losses, and leads to 20% lowered compression ring losses for an entire combustion cycle of the investigated operation point. In the future, such tribological concepts can be deployed in internal combustion engines that are powered by sustainable hydrogen or methanol.     

Strained Dehydrogenative Ring Closure of Phenylcarbazoles

What does it take to force a rigid and strained dehydrogenative ring closure, for example, in phenylcarbazoles? Since the works of Buchwald and Fagnou, palladium‐catalysed ring‐closing dehydrogenative reactions are legion, but will not operate when the strain at the reductive elimination stage becomes too large. We propose here a “muscled up” super‐oxidative palldium‐catalysed C H activation method for the ring closure of strained phenylcarbazoles.

     

Microfluidics for Rapid Detection of Live Pathogens

Rapid, sensitive, and selective detection of live pathogens remains a key priority for quality control and risk assessment. While conventional methods often require complicated workflows, costly reagents, lab equipment, and are time-consuming, rendering them inadequate for field testing and low-resource settings. Increased attention has been drawn to developing alternative low-cost and rapid methods to detect on-site live pathogens in different environmental matrices. Among them, microfluidic devices that integrate various laboratory functions in a miniaturized manner have proven to be a promising tool for the rapid and sensitive detection of pathogens. Herein, the development of microfluidic devices specifically designed for the detection of live pathogens is discussed along a concise summary of novel microfluidics systems recently developed, contrasted to conventional methods regarding assay time, the limit of detection, and target organisms. These include a variety of micro total analysis systems (µTAS) and microfluidic paper-based analytical devices (µPADs) in combination with molecular methods and traditional live cell detection techniques, such as cell culture, DNA intercalating dyes, resazurin, and immobilized bioreceptors (e.g., aptamers and capture antibodies). Furthermore, insights on the future perspectives of microfluidics for live pathogen detection with a highlight on the rapid and low-cost method development for field testing are provided.     

Pneumatic Pressure Control Using on-off Valves with Pulse Width Modulation

Servomotor-controlled valves are widely used in industry for pressure control of pneumatic systems. However, as a first stage, they can cause significant hysteresis that can result in loss of pressure or flow control accuracy at the second stage level. To reduce this effect and improve accuracy, a possible solution relies on the use of on-off switching valves controlled by Pulse Width Modulation (PWM). This approach is studied, firstly by analytically determining how the PWM parameters have to be tuned according to the on-off valve characteristics, secondly by ensuring that these characteristics provide the desired behavior of the system, and finally by experimentally verifying whether the PWM control can successfully reduce hysteresis, without decreasing the application range.     

Local Degradation of PEDOT:PSS on Silicon Nanostructures Using Scanning Electrochemical Microscopy

Conducting polymers show attractive characteristics as electrode materials for micro-electrochemical energy storage (MEES). However, there is a lack of characterization techniques to study conjugated/conducting polymer-based nanostructured electrodes. Here, scanning electrochemical microscopy (SECM) is introduced as a new technique for in situ characterization and acceleration of degradation processes of conducting polymers. Electrodes of PEDOT:PSS on flat silicon, silicon nanowires (SiNWs) and silicon nanotrees (SiNTrs) are analyzed by SECM in feedback mode with approach curves and chronoamperometry. The innovative degradation method using SECM reduces the time required to locally degrade polymer samples to a few thousand seconds, which is significantly shorter than the time usually required for such studies. The degradation rate is modeled using Comsol Multiphysics. The model provides an understanding of the phenomena that occur during degradation of the polymer electrode and describes them using a mathematical constant A₀ and a time constant τ.