Ultrafast nonlinear response of gold gyroid three-dimensional metamaterials

We explore the nonlinear optical response of 3D gyroidal metamaterials, which show >10-fold enhancements compared to all other metallic nanomaterials as well as bulk gold. A simple analytical model for this metamaterial response shows how the reflectivity spectrum scales with the metal fill fraction and the refractive index of the material that the metallic nanostructure is embedded in. The ultrafast response arising from the interconnected 3D nanostructure can be separated into electronic and lattice contributions with strong spectral dependences on the dielectric filling of the gyroids, which invert the sign of the nonlinear transient reflectivity changes. These metamaterials thus provide a wide variety of tuneable nonlinear optical properties, which can be utilised for frequency mixing, optical switching, phase modulators, novel emitters, and enhanced sensing.This is the author's accepted manuscript. The final version is available from APS in Physical Review Applied at http://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.2.044002#fulltext#fulltext

Structural Color and Iridescence in Transparent Sheared Cellulosic Films

Shear transparent cellulose free-standing thin films can develop iridescence similar to that found in petals of the tulip Queen of the Night. The iridescence of the film arises from the modulation of the surface into bands periodically spread perpendicular to the shear direction. Small amounts of nanocrystalline cellulose (NCC) rods in the precursor liquid-crystalline solutions do not disturb the optical properties of the solutions but enhance the mechanical characteristics of the films and affects their iridescence. Smaller bands periodicity, not affected by the NCC rods, slightly deviated from the shear direction is also observed. NCCs are crucial to tune and understand the film's surface features formation. Our findings could lead to new materials for application in soft reflective screens and devices

Sustainability, Innovation, and Green Chemistry in the Production and Valorization of Phenolic Extracts from Olea europaea L.

This paper describes a circular economy process based on environmentally and economically sustainable procedures which was applied to the sector of olive oil processing on an industrial scale. Olea europaea L. tissues and by-products represent a renewable and low-cost source of polyphenols, in particular hydroxytyrosol (HTyr), a naturally occurring compound well known for its biological properties. Specifically, green leaves (GL), dried leaves (DL), and pitted olive pulp were treated with water in a pneumatic extractor to obtain the corresponding polyphenolic extracts. Three standardized fractions, named Soft Extract Olea GL, Soft Extract Olea DL, and Soft Extract Olea HTyr resulted after the following two steps: a separation process carried out by membrane technology, and a concentration step performed under reduced pressure and low temperature. The polyphenolic fractions showed antiradical activity and have potential industrial applications in the food, nutraceutical, pharmaceutical, feed, and agronomic fields. Novel functionalized extracts containing hydroxytyrosol methyl carbonate (HTyr-MC) were obtained from Soft Extract Olea HTyr through an innovative approach based on green chemistry procedures, which appear to be a promising tool to increase the applications of the polyphenolic extracts

Characterization of Volatile and Flavonoid Composition of Different Cuts of Dried Onion (Allium cepa L.) by HS-SPME-GC-MS, HS-SPME-GC×GC-TOF and HPLC-DAD

Onion is widely used worldwide in various forms for both food and medicinal applications, thanks to its high content of phytonutrients, such as flavonoids and volatile sulfur compounds. Fresh onion is very perishable and drying is widely applied for extending shelf-life, thus obtaining a very easy-to-use functional food ingredient. The flavonoid and volatile fractions of different onion cuts (flakes, rings) prepared through different drying cycles in a static oven, were characterized by high-performance liquid chromatography with a diode-array detector HPLC-DAD, Head Space-Solid Phase Micro Extraction followed by Gas Chromatography coupled with Mass Spectrometry (HS-SPME-GC-MS) and Head-Space Solid Phase Micro Extraction followed by comprehensive two-dimensional Gas-Chromatography (HS-SPME-GC×GC-TOF). Onion flakes showed a significantly higher flavonoid content (3.56 mg g−1) than onion rings (2.04 mg g−1). Onion flakes showed greater amount of volatile organic compounds (VOCs) (127.26 mg g−1) than onion rings (42.79 mg g−1), with different relative amounts of di- and trisulfides—disulfides largely predominate the volatile fraction (amounts over 60% on the total volatile content), followed by trisulfides and dipropyl disulfide and dipropyl trisulfide were the most abundant VOCs. HS-SPME-GC×GC-TOF allowed for the detection of the presence of allylthiol, diethanol sulfide, 4,6-diethyl1,2,3,5-tetrathiolane, not detected by HS-SPME-GC-MS, and provided a fast and direct visualization and comparison of different samples. These results highlight different nutraceutical properties of dried onion samples processed otherwise, only differing in shape and size, thus pointing out potentially different uses as functional ingredients

Uncoupling growth and division in Chlamydomonas reinhardtii colonies : consistent cell cycle regulation under confinement

A planar cell microcolony served as a model system to study the impact of inter-cellular crowding and cell-matrix interactions upon the cell cycle. We studied the development over several days of Chlamydomonas reinhardtii microcolonies, grown from single cells, using a bespoke experimental setup allowing timelapse fluorescence microscopy. Through precise cell segmentation and lineage tracking of a large systematic dataset, characterizing individual cell growth and divisions, we uncovered how the external matrix influenced cell cycle and morphology. Experiments also revealed spatial heterogeneity among cells within colonies, providing insights into the effects of contact inhibition and micro-gradients of mass transfer. A radial propagation of ring-like pattern, characterised by variations in parent cell size, indicated complex spatio-temporal dynamics in the regulation of the cell cycle within the constrained environment. The mechanisms of commitment and mitotic sizing remained consistent within colonies under this mechanical confinement. These findings contribute to a broader understanding of how matrix immobilisation affects C. reinhardtii, with implications for alternative culture formats such as biofilms and hydrogel encapsulation—approaches increasingly used in biohybrid applications including biophotovoltaics and bioremediation

Therapeutic Potential of Saffron Extract in Mild Depression: A Study of Its Role on Anhedonia in Rats and Humans

Drugs generally used in major depressive disorder are considered inappropriate for the more common milder forms. The efficacy of saffron extracts has been demonstrated in mild to moderate depression and in preclinical models of depression. However, evidence of saffron activity on reduced hedonic responsiveness and motivational anhedonia is limited. Since dopamine transmission dysfunctions are crucially involved in anhedonia and saffron seems to positively modulate dopamine release, we studied the potential antidepressant and anti-anhedonic effects of a standardized formulation of saffron extract in preclinical models of anhedonia-like behaviors, and patients diagnosed with unipolar or bipolar depression. We tested saffron activity in a rat model of stress-induced motivational anhedonia using sucrose self-administration protocols and investigated the molecular underpinnings of this effect focusing on DARPP-32 phosphorylation pattern in response to a reinforcer and BDNF-TrkB signaling, in the nucleus accumbens and medial prefrontal cortex. In parallel, with a pilot double-blind placebo-controlled study we investigated whether saffron add-on therapy reduced symptoms of depression and anhedonia, measured by the Montgomery-& Aring;sberg Depression Rating Scale. Repeated saffron administration restored motivation and reactivity to reward-associated cues in anhedonic rats, likely modulating dopaminergic transmission and BDNF-TrkB signaling. In depressed patients, an 8-week saffron add-on therapy induced a global improvement in depressive symptoms and a significant reduction in anhedonia. The study supports a pro-motivational effect of saffron and suggests a potentially useful saffron-based augmentation strategy in anhedonic patients, albeit with limitations due to small sample size and short trial duration