Classification of analytics, sensorics, and bioanalytics with polyelectrolyte multilayer capsules

Polyelectrolyte multilayer (PEM) capsules, constructed by LbL (layer-by-layer)-adsorbing polymers on sacrificial templates, have become important carriers due to multifunctionality of materials adsorbed on their surface or encapsulated into their interior. They have been also been used broadly used as analytical tools. Chronologically and traditionally, chemical analytics has been developed first, which has long been synonymous with all analytics. But it is not the only development. To the best of our knowledge, a summary of all advances including their classification is not available to date. Here, we classify analytics, sensorics, and biosensorics functionalities implemented with polyelectrolyte multilayer capsules and coated particles according to the respective stimuli and application areas. In this classification, three distinct categories are identified: (I) chemical analytics (pH; K+, Na+, and Pb2+ ion; oxygen; and hydrogen peroxide sensors and chemical sensing with surface-enhanced Raman scattering (SERS)); (II) physical sensorics (temperature, mechanical properties and forces, and osmotic pressure); and (III) biosensorics and bioanalytics (fluorescence, glucose, urea, and protease biosensing and theranostics). In addition to this classification, we discuss also principles of detection using the above-mentioned stimuli. These application areas are expected to grow further, but the classification provided here should help (a) to realize the wealth of already available analytical and bioanalytical tools developed with capsules using inputs of chemical, physical, and biological stimuli and (b) to position future developments in their respective fields according to employed stimuli and application areas

Mesoscale ionospheric plasma irregularities and scintillation over Svalbard

This thesis investigates how navigation signals are compromised by ionospheric plasma irregularities in the auroral and polar ionosphere over Svalbard. In 2013, four multiconstellation global navigation satellite system (GNSS) receivers were installed in NyÅlesund, Longyearbyen, Hopen, and Bjørnøya. These receivers provide unprecedented coverage of scintillation and plasma density (total electron content) in the region. The four research papers in this thesis are detailed case studies investigating mesoscale irregularities and scintillation.We use data from these GNSS receivers, all-sky imagers, coherent and incoherent scatter radars, ionosondes, and in-situ satellite measurements. Paper I [van der Meeren et al., 2014] investigates scintillation and irregularities on the front of a tongue of ionization (TOI) in the polar cap. Moderate scintillation and structuring is observed on the leading edge of the TOI. We employ a novel method where we use spectrograms of the phase of raw GNSS signals to show that the structuring is real and not due to erroneous data detrending of the σφ phase scintillation index. Paper II [Oksavik et al., 2015] investigates irregularities in the dayside auroral region, specifically in relation to poleward-moving auroral forms (PMAFs). Scintillation is strongly localized to these intense and transient features, even in the presence of polar cap patches. Paper III [van der Meeren et al., 2015] investigates scintillation from substorm auroral emissions as polar cap patches enter the nightside auroral oval. The most severe scintillation is found when the auroral precipitation coincides with polar cap patches. The scintillation is strongly localized to signals intersecting intense auroral emissions. Paper IV [van der Meeren et al., 2016] investigates irregularities during quiet geomagnetic conditions. We find weak irregularities in relation to a stable and intense transpolar arc, but no scintillation is seen. The main results in this thesis are: Scintillation-producing irregularities can exist on the leading edge of TOIs, in PMAFs, and in substorm auroral precipitation when patches enter the nightside auroral oval. Of these, auroral precipitation on top of pre-existing plasma patches seems to produce the strongest scintillation. The scintillation generally shows a high degree of localization, varying significantly over distances of ∼ 100km. This clearly indicates the need for a dense network of scintillation receivers in the polar ionosphere to fully resolve this spatial variation. It also shows that detailed case studies are important to complement the averaged, static, large-scale picture common in statistical studies. We have developed a novel method of using spectrograms of the phase of raw GNSS signals to get a more complete view of irregularities than aggregate scintillation indices like σφ . Furthermore, our method does not require data detrending, and it is therefore more robust than traditional scintillation indices that are frequently used by the community. The observed irregularities cover a wide range of spatial scale sizes, from decameters to several kilometers. Irregularities at these spatial scale sizes can affect radio wave propagation from HF to GNSS frequencies. </ul

Self-assembly of Tween 80 micelles as nanocargos for oregano and trans-cinnamaldehyde plant-derived compounds

The self-assembly of Tween 80 (T80) micelles loaded with plant-based oregano essential oil (OR) and trans-cinnamaldehyde (TCA) was studied. The effect of different factors, including the surfactant to oil ratio, the presence of sodium chloride, thermal treatment, and dilution on their formation and physicochemical stability was evaluated. The creation of nano-cargos was confirmed by TEM. The self-associated structures had z-average droplet diameters of 92 to 337 nm without any energy input. Whereas addition of 10% (w/v) NaCl prevented the formation of oregano essential oil nano-assemblies of T80, swollen micelles containing TCA were successfully produced. Moreover, the OR or TCA loaded-micelles had only a slight droplet size variation upon thermal treatment. Ultimately, their antibacterial activity analysis against some food pathogens revealed that the encapsulation of OR and TCA within micelles crucially improved their antibacterial activity. These straightforward and cost-effective designed systems can be applicable in different products, including foods and agrochemicals

Water and oil signal assignment in low-moisture mozzarella as determined by time-domain NMR T2 relaxometry

A time-domain H-1 nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T-2 relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr-Purcell-Meiboom-Gill (CPMG) sequence and a free-induction decay CPMG (FID-CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T-2 distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low-moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process