Manufacturing and Mechanical Behaviour of Scalmalloy Lattice Structures: Experimental Validation and Model.

This study investigates the influence of process parameters on the fabrication and mechanical performance of Scalmalloy lattice structures produced via laser powder bed fusion (PBF-LB) and their mechanical responses at different cell size. A full-factorial design of experiments was employed to evaluate the effect of scan speed, hatch distance, and downskin power on internal porosity and dimensional accuracy. Regression models revealed significant relationships, with optimised parameters identified at a scan speed of 700 mm/s, hatch distance of 0.

Biophotonic function of the calcium carbonate skeleton in Lithothamnion crispatum: A possible adaptation of coralline algae to low-light environments.

Coralline algae (Corallinophycidae, Rhodophyta) have adapted to a broad range of marine habitats, including low-light mesophotic zones, yet the potential role of their high-Mg calcite skeleton in light harvesting remains poorly investigated. Here, we examine the skeletal architecture of Lithothamnion crispatum rhodoliths through X-ray micro-computed tomography (μ-CT) and scanning electron microscopy (SEM), revealing a distinct Voronoi-like tessellation of the epithallial cells associated with a nearly hyperuniform arrangement of submicrometric pores. This structural organization can promote the penetration of scattered light into the thallus, enhancing photon availability in deeper tissues.

Resolving SPARC-HSA binding kinetics with an ultrasensitive photonic sensor based on bound states in the continuum.

Secreted protein acidic and rich in cysteine (SPARC) is critical in cell-matrix interactions and tissue remodeling. It influences tumor progression through its affinity for human serum albumin (HSA) - the most abundant plasma protein, which also plays a crucial role in drug delivery. Strong molecular binding leads to a dissociation constant K in the nanomolar range.

Molecularly Imprinted Polymer Sensor Empowered by Bound States in the Continuum for Selective Trace-Detection of TGF-beta.

The integration of advanced materials and photonic nanostructures can lead to enhanced biodetection capabilities, crucial in clinical scenarios and point-of-care diagnostics, where simplified strategies are essential. Herein, a molecularly imprinted polymer (MIP) photonic nanostructure is demonstrated, which selectively binding to transforming growth factor-beta (TGF-β), in which the sensing transduction is enhanced by bound states in the continuum (BICs). The MIP operating as a synthetic antibody matrix and coupled with BIC resonance, enhances the optical response to TGF-β at imprinted sites, leading to an augmented detection capability, thoroughly evaluated through spectral shift and optical lever analogue readout.

Directive giant upconversion by supercritical bound states in the continuum.

Photonic bound states in the continuum (BICs), embedded in the spectrum of free-space waves with diverging radiative quality factor, are topologically non-trivial dark modes in open-cavity resonators that have enabled important advances in photonics. However, it is particularly challenging to achieve maximum near-field enhancement, as this requires matching radiative and non-radiative losses. Here we propose the concept of supercritical coupling, drawing inspiration from electromagnetically induced transparency in near-field coupled resonances close to the Friedrich-Wintgen condition.

Optical Biosensors Based on Photonic Crystals Supporting Bound States in the Continuum.

A novel optical label-free bio-sensing platform based on a new class of resonances supported in a photonic crystal metasurface is reported herein. Molecular binding is detected as a shift in the resonant wavelength of the bound states in the continuum of radiation modes. The new configuration is applied to the recognition of the interaction between protein p53 and its protein regulatory partner murine double minute 2 (MDM2).

Revealing metallic ink in Herculaneum papyri.

Writing on paper is essential to civilization, as Pliny the Elder remarks in his Natural History, when he describes the various types of papyri, the method of manufacturing them, and all that concerns writing materials in the mid-first century AD. For this reason, a rigorous scientific study of writing is of fundamental importance for the historical understanding of ancient societies. We show that metallic ink was used several centuries earlier than previously thought.

Revealing letters in rolled Herculaneum papyri by X-ray phase-contrast imaging.

Hundreds of papyrus rolls, buried by the eruption of Mount Vesuvius in 79 AD and belonging to the only library passed on from Antiquity, were discovered 260 years ago at Herculaneum. These carbonized papyri are extremely fragile and are inevitably damaged or destroyed in the process of trying to open them to read their contents. In recent years, new imaging techniques have been developed to read the texts without unwrapping the rolls.

Digital holographic microscopy characterization of superdirective beam by metamaterial.

Digital holographic microscopy (DHM) has been successfully applied for the first time to characterize the radiative out-of-plane emission properties of a superdirective device. Complementarily to near-field microscopy, DHM allows us to reconstruct the beam in the far-field region. The angular dispersion of the light beam radiated from a grating composed of air and anti-air metamaterial has been determined, and the proposed technique has highlighted a collimation degree higher than 0.

An extraordinary directive radiation based on optical antimatter at near infrared.

In this paper we discuss and experimentally demonstrate that in a quasi- zero-average-refractive-index (QZAI) metamaterial, in correspondence of a divergent source in near infrared (λ = 1.55 μm) the light scattered out is extremely directive (Δθ(out) = 0.06°), coupling with diffraction order of the alternating complementary media grating.

Two-dimensional photonic aperiodic crystals based on Thue-Morse sequence.

We investigate from a theoretical point of view the photonic properties of a two dimensional photonic aperiodic crystal. These structures are obtained by removing the lattice points from a square arrangement, following the inflation rules emerging from the Thue-Morse sequence. The photonic bandgap analysis is performed by means of the density of states calculation.

Influence of surface termination on negative reflection by photonic crystals.

When a wave impinges obliquely to the interface of a Photonic Crystal (PhC), the wave can be completely reflected in counter-propagating direction instead of the usually expected specular direction. However the beam is totally specularly reflected with a simple modification of the surface termination. The analysis of the time average Poynting vector evidences that PhC termination modifies the energy flow and determines the reflection properties.

A polarizing beam splitter using negative refraction of photonic crystals.

Light passing through a photonic crystal can undergo a negative or a positive refraction. The two refraction states can be functions of the contrast index, the incident angle and the slab thickness. By suitably using these properties it is possible to realize very simple and very efficient optical components to route the light.

Negative refraction in Photonic Crystals: thickness dependence and Pendellösung phenomenon.

We show that the refracted wave at the exit surface of a Photonic Crystal (PhC) slab is periodically modulated, in positive or in negative direction, changing the slab thickness. In spite of an always increasing literature, the effect of the thickness in negative refraction on PhC's does not seem to be appropriately considered. However such an effect is not surprising if interpreted with the help of Dynamical Diffraction Theory (DDT), which is generally applied in the x-ray diffraction.