Postharvest storage and cooking techniques affect the stability of glucosinolates and myrosinase activity of Andean mashua tubers (Tropaeolum tuberosum)

The identification and quantification of Glucosinolates (Gls) via UPLC^® MS-MS/PDA/qToF in ten mashua cultivars was carried out. Gls total contents were within the 4.9–54.2 μmol g⁻¹ dry matter range, of which 96–99% corresponded to glucoaubrietin. Other less abundant Gls were glucotropaeolin and tentatively two isomers of hydroxybenzyl Gls. Postharvest refrigeration and shade storage conditions increased the content of Gls up to day 6 in 39.7% and 51.5% respectively. Sun exposure increased the Gls content in 40% up to day 3 but from day 6 considerable losses were attained (92% at day 15). Low correlation levels (R²) between the Gls and myrosinase (MYR) activity of 0.57, 0.28 and 0.39 for the refrigeration, shade and sun exposure treatments were obtained. The cooking regimes tested, boiling, microwaving and baking totally inactivated MYR without affecting the Gls content.     

Organic Photovoltaic Sensors for Photocapacitive Stimulation of Voltage‐Gated Ion Channels in Neuroblastoma Cells

Organic semiconductors are emerging as promising candidates for novel electrically self‐sufficient photovoltaic prosthetics for neurostimulation, especially for restoration of light sensitivity in degenerate retina. Considering future applications, it is essential to gain fundamental insight into the signaling mechanisms at the organic photosensor–electrolyte–neuron interface. Particularly, targeting voltage‐gated ion channels by a pure photocapacitive stimulation is a preferred therapeutic approach as it avoids redox reactions involved in Faradaic charge injection. The present study investigates whether single neuroblastoma (N2A) cells, grown on a photosensor based on a small molecular squaraine:fullerene photoactive layer blend, optionally covered with silicon dioxide, can be activated by photocapacitive stimulation. Indeed, upon pulsed illumination, a rapid transient photocurrent strongly depolarizes the membrane potential and subsequently activates fast‐responding voltage‐gated sodium channels. The dielectric top coating on the organic layer ensures sufficient capacitive charge injection efficiency while maintaining the rapid response of the device. Due to the high irradiance level required for photocapacitive stimulation, another slower, independent, and unintended, nonelectrical signaling pathway is identified. This activates voltage‐gated potassium channels, presumably by photothermal effects. The present study provides the basis for further improvements on standalone photovoltaic neurostimulating platforms based on organic photoactive layers.     

3D Printed Prisms with Tunable Dispersion for the THz Frequency Range

Here, we present a 3D printed prism for THz waves made out of an artificial dielectric material in which the dispersion can be tuned by external compression. The artificial material consists of thin dielectric layers with variable air spacings which has been produced using a fused deposition molding process. The material properties are carefully characterized and the functionality of the prisms is in a good agreement with the underlying theory. These prisms are durable, lightweight, inexpensive, and easy to produce.     

A THz Tomography System for Arbitrarily Shaped Samples

We combine a THz time-domain spectroscopy system with a robotic arm. With this scheme, the THz emitter and receiver can be positioned perpendicular and at defined distance to the sample surface. Our system allows the acquisition of reflection THz tomographic images of samples with an arbitrarily shaped surface.     

3D Printed Terahertz Focusing Grating Couplers

We have designed, constructed and characterized a grating that focuses electromagnetic radiation at specific frequencies out of a dielectric waveguide. A simple theoretical model predicts the focusing behaviour of these chirped gratings, along with numerical results that support our assumptions and improved the grating geometry. The leaky waveguide was 3D printed and characterized at 120 GHz demonstrating its potential for manipulating terahertz waves.     

Engineered silica nanoparticles as additives in lubricant oils

Silica nanoparticles (SiO₂ NPs) synthesized by the sol–gel approach were engineered for size and surface properties by grafting hydrophobic chains to prevent their aggregation and facilitate their contact with the phase boundary, thus improving their dispersibility in lubricant base oils. The surface modification was performed by covalent binding of long chain alkyl functionalities using lauric acid and decanoyl chloride to the SiO₂ NP surface. The hybrid SiO₂ NPs were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, simultaneous differential thermal analysis, nuclear magnetic resonance and dynamic light scattering, while their dispersion in two base oils was studied by static multiple light scattering at low (0.01% w/v) and high (0.50%w/v) concentrations. The nature of the functional layer and the functionalization degree seemed to be directly involved in the stability of the suspensions. The potential use of the functional SiO₂ NPs as lubricant additives in base oils, specially designed for being used in hydraulic circuits, has been outlined by analyzing the tribological properties of the dispersions. The dendritic structure of the external layer played a key role in the tribological characteristics of the material by reducing the friction coefficient and wear. These nanoparticles reduce drastically the waste of energy in friction processes and are more environmentally friendly than other additives.     

Analysis of activated sludge process using multivariate statistical tools—a PCA approach

Twelve original physical variables of an activated sludge wastewater treatment system are considered. These cross-correlated variables are transformed in new ones that are not correlated by the use of PCA (principal component analysis), a powerful tool for analysis, monitoring and diagnostics of wastewater treatment processes. Just three principal components explain most of the system total variability (78% of total variance). Thus, the ability to describe the overall characteristics of the process using only three principal components will make the analysis, monitoring and diagnostic of the system easier.

Three groups of variables characterizing the system are detected. The first group identifies variables that represent micro-organisms and inert particulate matter arising from cellular decay, while the second group refers to substrates and flow rate. The third group is related to the pH. Based on these results, the present paper shows how to enlarge the ways of interpreting the characteristics of activated sludge wastewater treatment system.     

Quality of packaged romaine lettuce hearts exposed to low-dose electron beam irradiation

We investigated the effects of low-dose electron beam irradiation (1.0, 1.5 and 3.2 kGy) on the quality of commercially prepackaged fresh romaine lettuce hearts. The impact of the irradiation treatment on the functionality of the package was also evaluated. Irradiated samples showed slight changes in color, but these changes were not significantly different (P >0.05) from the nonirradiated (control) samples. Sample firmness decreased by 49.58% (leaves) and 29.13% (ribs), as the dose level increased. Sensory attributes such as overall quality, color, sogginess, and off-flavor were found less acceptable at the higher dose level. Irradiation affected the respiration rates inside the packages, with lower (10.38%) O₂ and higher CO₂ levels than the control. Irradiation at 1.5 and 3.2 kGy dose levels improved the oxygen barrier capability of the low-density polyethylene (LDPE) bags (7.67% and 4.48%, respectively). Water vapor permeability was unaffected at all the irradiation dose levels. The stiffness of LPDE films did not change due to irradiation treatment. Results from sensory evaluation of produce overall quality suggest a potential fungicidal effect of low-dose irradiation (1.0 kGy) of packaged romaine lettuce hearts without altering the overall quality of the produce as well as the LDPE-packaging characteristics.     

Organic molecular nanotechnology

A new route to bottom-up organic nanotechnology is presented. Molecular building blocks with specific optoelectronic properties are designed and grown via directed self-assembly arrays of morphologically controlled light-emitting organic nanofibers on template surfaces. The fibers can be easily transferred from the growth substrate to device platforms either as single entities or as ordered arrays. Due to the extraordinary flexibility in the design of their optoelectronic properties they serve as key elements in next-generation nanophotonic devices.     

On the Influence of Delay Line Uncertainty in THz Time-Domain Spectroscopy

Terahertz time-domain spectroscopy (THz TDS) is a well-known tool for material analysis in the terahertz frequency band. One crucial system component in every time-domain spectrometer is the delay line which is necessary to accomplish the sampling of the electric field over time. Despite the fact that most of the uncertainty sources in TDS have been discussed, the delay line uncertainty has not been considered in detail. We model the impact of delay line uncertainty on the acquired THz TDS data. Interferometric measurements of the delay line precision and THz time-domain data are used to validate the theoretical model.