Plastic recycling stripped naked - from circular product to circular industry with recycling cascade.

This perspective combines various expertise to develop and analyse the concept of technology cascade for recycling waste plastics with the goal of displacing as much fossil crude oil as possible. It thereby presents archetype recycling technologies with their strengths and weaknesses. It then combines them in various cascades to process a representative plastic mix, and determines how much (fossil) naphtha could be displaced and at which energy consumption. The cascades rely on a limited number of parameters that are fully reported in supplementary information and that were used in a simple and transparent spreadsheet model. The calculated results bust several common myths in plastic recycling, e. g. by prioritizing here recycled volume over recycling efficiency, and prioritizing circular industry over circular products . It unravels the energy cost of solvent-based recycling processes, shows the key role of gasification and the possibility to displace up to 70 % of the fossil feedstock with recycled carbon, a recycling rate that compares well with that aluminium, steel or paper. It suggests that deeper naphtha displacement would require exorbitant amount of energy. It therefore argues for the need to complement recycling with the use of renewable carbon, e. g. based on biomass, to fully defossilise the plastic industry.

Systematic reduction of hyperspectral images for high-throughput plastic characterization.

Hyperspectral Imaging (HSI) combines microscopy and spectroscopy to assess the spatial distribution of spectroscopically active compounds in objects, and has diverse applications in food quality control, pharmaceutical processes, and waste sorting. However, due to the large size of HSI datasets, it can be challenging to analyze and store them within a reasonable digital infrastructure, especially in waste sorting where speed and data storage resources are limited. Additionally, as with most spectroscopic data, there is significant redundancy, making pixel and variable selection crucial for retaining chemical information. Recent high-tech developments in chemometrics enable automated and evidence-based data reduction, which can substantially enhance the speed and performance of Non-Negative Matrix Factorization (NMF), a widely used algorithm for chemical resolution of HSI data. By recovering the pure contribution maps and spectral profiles of distributed compounds, NMF can provide evidence-based sorting decisions for efficient waste management. To improve the quality and efficiency of data analysis on hyperspectral imaging (HSI) data, we apply a convex-hull method to select essential pixels and wavelengths and remove uninformative and redundant information. This process minimizes computational strain and effectively eliminates highly mixed pixels. By reducing data redundancy, data investigation and analysis become more straightforward, as demonstrated in both simulated and real HSI data for plastic sorting.

Surface Fatigue Behavior of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate.

In wind turbine gearboxes, (near-)surface initiated fatigue is attributed to be the primary failure mechanism. In this work, the surface fatigue of a hydrogenated tungsten carbide/amorphous carbon (WC/aC:H) thin-film was tested under severe cyclic tribo-contact using polyalphaolefin (PAO) and PAO + zinc dialkyldithiophosphate (ZDDP) lubricants. The film was characterized in terms of its structure and chemistry using X-ray diffraction, analytical transmission electron microscopy, including electron energy loss spectroscopy (EELS), as well as X-ray photoelectron spectroscopy (XPS). The multilayer carbon thin-film exhibited promising surface fatigue performance showing a slight change in the hybridization state of the aC:H matrix. Dehydrogenation of the thin-film and subsequent transformation of cleaved C-H bonds to nonplanar sp2 carbon rings were inferred from EELS and XPS results. While tribo-induced changes to the aC:H matrix were not influenced by a nanometer-thick ZDDP reaction-film, the rate of oxidation of WC and its oxidation state were affected. While accelerating surface fatigue on a steel surface, the ZDDP-tribofilm protected the WC/aC:H film from surface fatigue. In contrast to the formation of polyphosphates from ZDDP molecules on steel surfaces, it appeared that on the WC/aC:H thin film surface, ZDDP molecules decompose to ZnO, suppressing the oxidative degradation of WC.

Gemini surfactants: new synthetic vectors for gene transfection.

The superior surfactant properties of cationic gemini surfactants are applied to the complex problem of introducing genes into cells. Of almost 250 new compounds tested, of some 20 different structural types, a majority showed very good transfection activity in vitro. The surfactant is shown to bind and compact DNA efficiently, and structural studies and calculations provide a working picture of the "lipoplex" formed. The lipoplex can penetrate the outer membranes of many cell types, to appear in the cytoplasm encapsulated within endosomes. Escape from the endosome--a key step for transfection--may be controlled by changes in the aggregation behavior of the lipoplex as the pH falls. The evidence suggests that DNA may be released from the lipoplex before entry into the nucleus, where the new gene can be expressed with high efficiency.

Compaction of DNA by gemini surfactants: effects of surfactant architecture.

The interaction between bacteriophage T4 DNA and cationic gemini surfactants was studied by the use of fluorescence microscopy. Upon addition of surfactant, DNA undergoes a transition from random coil to globule, with an intermediate coexistence region. The state behavior of a DNA-gemini surfactant system was found to depend on spacer length, valency, head group size, and tail length. A series of alkanediyl-alpha,omega-bis-(dimethylalkylammonium bromide) surfactants with fixed tail length and variable spacer length s showed a minimum of compaction efficiency at s=6 due to the competition between entropy loss and enthalpy gain. This occurs at roughly the same spacer length at which the critical micellization concentration shows a maximal value (at s=5). In comparison with a single-tailed divalent surfactant (12-3-1) it was shown that the two-tailed equivalent (12-3-12) was more efficient in compacting DNA. A series of gemini surfactants based on cationic peptides with a alpha,omega-diamino alkyl spacer showed similar behavior upon changing the spacer length. Additionally, two surfactants based on diastereomers of tartaric acid with hexadecanoic acid tails and alpha,omega-diaminopropanyl and spermidine head groups, respectively, showed effects of head group size that depended strongly on entropy effects. The dependence on valency of the head group is found to be similar to what is known for mono- and multivalent ions, the latter being more efficient per unit of charge.