Rare earth-doped Y₂O₃ phosphors represent a class of fluorescent materials that have unique optical characteristics and properties, which are reflected in high color purity and long lifetime, with the possibility of covering the entire electromagnetic spectrum, along with low cytotoxicity. In this paper, we propose the synthesis of crystalline Nd³⁺-doped Y₂O₃ nanoparticles for the development of fluorescent labels with applicability in imaging. The nitrates of the two main cations, urea as a precipitating agent, and sea buckthorn (Hippophae rhamnoides) extract are the raw materials used in the precipitation procedure to obtain the oxide precursor. Thermal decomposition of the precursor occurs at 600°C in the presence of glycerin used as a combustion agent. By controlling the parameters, we oriented the process towards obtaining sufficiently small dimensions for efficient visualization of the distributions of target molecules in imaging, but no smaller than 10 nm to avoid the problem of cytotoxicity. SEM analysis shows well-defined particles with a spherical shape, smooth surface, no defects, and an average size of 50 nm. Analysis by X-ray diffraction, FTIR and EDX spectroscopy demonstrates the purity and high degree of crystallinity of the developed fluorescent labels and the possibility of using these types of materials in the field of biotechnology, as a result of meeting structural requirements. The study of the optical properties of doped phosphor shows red-shifted absorption spectra relative to Y₂O₃, and by excitation at 980 nm, multiple emission peaks in the NIR region were observed. The synthesis of NIR-emitting phosphors for biomedical applications is the main objective of this work, as they are less absorbed and scattered by tissue structures, and can achieve high penetration efficiency.

Acknowledgements: This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS-UEFISCDI, project number PN-IV-P2-2.1-TE-2023-0417, within PNCDI IV.

This study presents the development of an innovative flat ceramic microfiltration membrane produced from low-cost and environmentally friendly raw materials. The approach is based on the valorization of marble waste powder in combination with natural clay, thereby addressing both the need for effective wastewater treatment and the sustainable reuse of industrial by-products. The fabrication process was carefully optimized through a statistical strategy using the Doehlert experimental design within the response surface methodology framework. This allowed for the systematic evaluation of key synthesis parameters, including marble waste content, sintering temperature, and dwell time, in order to identify conditions leading to high-performance membranes.

The optimized membranes exhibited a well-balanced combination of structural, mechanical, and functional characteristics, making them suitable for microfiltration applications. Their porosity and microstructural uniformity ensured efficient liquid–solid separation, while their mechanical strength provided stability under operating conditions. In addition, the materials demonstrated strong resistance to aggressive chemical environments, particularly under alkaline conditions, thus confirming their durability for long-term use.

Performance tests with real industrial wastewater further confirmed the effectiveness of the membranes. Substantial improvements in water clarity and notable reductions in organic load indicators were observed, highlighting their ability to remove suspended solids and partially reduce dissolved contaminants.

Overall, this research demonstrates the potential of sustainable ceramic membranes based on natural clay and marble waste as viable, eco-friendly alternatives to conventional filtration materials. By combining waste valorization, low production costs, and efficient water purification capacity, these membranes represent a promising solution for industrial wastewater treatment and resource-efficient water management.

This work experimentally compares the operating characteristics of dye-sensitized solar cells (DSSCs) with cis-bis(isothiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylato)ruthenium(II) (N3) dye for two iodide/tri-iodide liquid electrolyte (AN-50) variants: (a) classic AN-50 iodide electrolyte, and (b) AN-50 modified with 4-n-pentyl-4’-cyanobiphenyl (5CB) liquid crystal (LC) additive (10% ) at an operating temperature of 300–303 K. The aim was to determine the effect of the 5CB additive on the open circuit voltage (Voc), short circuit current (Isc), fill factor (FF), power of the real cell (Pmax) parameters and resistive loss indices (Rs—Joule effect losses; Rsh—shunt resistance) and to formulate mechanistic conclusions (ion transport vs. recombination/interface). For each sample, a quasi-static measurement run was performed under constant illumination (116 klx) and controlled sample temperature. Load conditions were varied over time (sweep), while the sample voltage V(t) and current I(t) were recorded. The current–voltage (I–V) and power–voltage (P–V) characteristics were determined from the (V, I) pairs after their time synchronization. The introduction of 5CB into the AN-50 electrolyte affects the balance between ion transport/diffusion of redox couples I⁻/I₃⁻ and recombination losses at the photoanode–electrolyte interface. The literature shows that LC used as electrolyte additives can increase the "transmission paths" of redox couples, which favors an increase in Isc; however, the effect is concentration-dependent and can be reversed if the additive content is too high. In the tested samples, higher Voc and Isc were observed on average compared to the single control, with a simultaneous lower FF. This combination is consistent with the hypothesis of (a) partial improvement in generation/transport (Isc), but (b) increased resistive-transport losses or changes in electrode kinetics that reduce FF. Due to the single control and different measurement dates, this conclusion should be considered preliminary and requires confirmation by measurements under identical conditions.

Lamellar mesophases based on lecithin are of interest for the development of topical formulations due to their ability to accommodate components of different polarity and their structural similarity to stratum corneum lipids. Rheological behavior is a key parameter that affects both the application properties and the release profile of active ingredients.

In this work, we investigated how the addition of gelatin and several plant extracts (dioscorea, onion, red wine) modifies the viscous properties of lamellar liquid crystals formed in a quaternary system: lecithin – olive oil – tea tree oil – water. All samples were prepared using a previously developed procedure; the presence of a lamellar mesophase was confirmed by polarized light microscopy. Rheological tests were carried out on a Haake Viscotester IQ rotational viscometer at 25 °C. All compositions exhibited pseudoplastic behavior, i.e., the effective viscosity decreased with increasing shear rate.

Incorporating gelatin solutions at concentrations of 1, 2, 3, and 5 % into the liquid‑crystalline matrix increased the viscosity in the shear rate range 0.01–1.0 s⁻¹ by factors of 1.23, 1.49, 1.58, and 1.79, respectively, compared to the control sample. The most pronounced effect was observed at 5 % gelatin, which can be attributed to the formation of a three‑dimensional gel network within the aqueous interlayers.

Plant extracts also significantly altered the rheological response. The dry extract of dioscorea raised the viscosity by a factor of 1.23 on average, whereas the alcoholic extract of dioscorea gave a 7.5‑ to 13.1‑fold decrease depending on the shear rate. Onion alcoholic extract resulted in a 3.4‑ to 9.6‑fold viscosity reduction. For red wine dry extract, a clear concentration dependence was found: at 1, 2, and 5 % the viscosity increased by factors of 1.40, 1.66, and 2.02, respectively. After two weeks of storage, all samples retained their liquid‑crystalline structure, indicating good physical stability.

The results demonstrate that the rheological properties of lecithin‑based lamellar phases are highly sensitive to the nature and concentration of incorporated additives. These findings provide a basis for tailoring the viscosity and release characteristics of lecithin liquid‑crystalline formulations intended for dermatological and cosmetic use.

Nematic liquid crystals possess long‑range orientational order described by a director field whose distortions are mainly determined by the Frank elastic constants for splay (K₁₁), twist (K₂₂), and bend (K₃₃)¹. In bent‑shaped dimers such as CB7CB, the bend elastic constant K₃₃ becomes anomalously low near the nematic twist–bend phase², strongly influencing director configurations and electro‑optic textures. When CB7CB is mixed with the rod‑like compound 8CB, the resulting nematic phase maintains the usual orientational order while inheriting a very low³ K₃₃ value, making the system ideal for studying elasticity‑affected textures.

This work demonstrates how such variations in elastic constants¹ shape the texture of a chiralized nematic. Usually adding a small amount of a chiral dopant to a nematic phase only induces a spontaneous twist and results in homogeneous textures. We show this is no longer the case with a reduced bend constant. Mixtures of 8CB and CB7CB were prepared and filled into planar and twisted‑nematic cells. Elastic constants K₁₁, K₂₂, and K₃₃ were then measured with changes in temperature and composition using impedance spectroscopy and electro‑optic response analysis. The texture evolution of these mixtures doped with the chiral compound S811 was observed using polarized optical microscopy. Mixtures with higher CB7CB content show a significant reduction in K₃₃, while K₁₁ and K₂₂ vary more moderately. This low‑K₃₃ regime leads to voltage‑induced striped and heliconical‑like textures, with periodicity varying with the temperature. Elastic anisotropy—particularly when K₃₃ becomes very small—plays a central role in forming and stabilizing non‑uniform nematic textures.

References: ¹F. C. Frank, Discuss. Faraday Soc. 25, 19 (1958).

²I. Dozov, Europhys. Lett. 56, 247 (2001).

³A. Aouini, M. Nobili, E. Chauveau, P. Dieudonné‑George, G. Damême, D. Stoenescu, I. Dozov, and C. Blanc, Crystals 10, 1110 (2020).

Polymer nanocomposites (PNCs) combine polymer matrices with nanofillers to achieve exceptional mechanical, thermal, and functional properties. However, understanding how inter-nanoparticle (NP) repulsive interactions influence structural assembly and transport properties in confined domains remains under-researched. In this study, we employ GPU-accelerated Langevin dynamics simulations to systematically investigate how varying inter-NP repulsive strength drives phase behaviour in strongly confined PNC systems. Semi-flexible polymer chains and spherical NPs were simulated in extremely confined (quasi-2D) geometries with fixed monomer and NP volume fractions. Structural properties were studied via radial distribution function, cluster analyses, crystallinity and nematic order parameter calculations, while diffusivity was assessed through mean-square displacement analysis. Depending on the strength of repulsion, the composite system self-assembles into distinct morphologies: i) a droplet phase, characterised by complete NP phase separation; ii) a slab phase featuring percolating networks and a maximum nematic order; iii) a broken-slab phase showing polymer infiltration and fragmented assemblies; and iv) a dispersed phase with ordered NP distribution, exhibiting increased smecticity at higher repulsion strengths and crystalline spatial organisation as confirmed by RDF and crystallographic analysis. Diffusivity exhibits non-monotonic behaviour, with optimal nanoparticle mobility at intermediate repulsive strengths, while polymer diffusivities show inverse trends indicating competing dynamics between the two components. These findings demonstrate that fine-tuning inter-nanoparticle repulsions provides precise control over structural phases and transport properties, offering design principles for PNCs with the required functionality.

The discovery of polar order in achiral liquid crystals has revolutionized the field of soft matter, offering properties comparable to solid-state ferroelectrics.

In this study, the dielectric response of several homologous series of rod-like compounds was analyzed, considering how molecular architecture determines polar properties. By analyzing several homologous series of rod-like compounds, we investigate how specific structural modifications, such as terminal groups and core substitutions, influence mesophase stability and electrical response. The primary focus is placed on the role of terminal groups, including nitro-, cyano-, and fluorine fragments. Additionally, we examine how minimal structural changes, such as the addition of a single methylene unit, can radically shift a material from a paraelectric to a ferroelectric state.

The research shows that the emergence of the ferroelectric order is driven by a specific collective mode. In this state, molecules within different domains vibrate in or out of phase depending on their polarization direction. We also analyzed two achiral smectic phases. In the ferroelectric smectic A phase, we observed a soft mode (amplitude mode) where the dielectric strength increases and the relaxation frequency decreases as the temperature decreases. By contrast, in the ferroelectric smectic C phase, a phason mode appears, similar to the Goldstone mode in chiral systems.

Furthermore, in a specially designed mixture, we observed very high values of electric permittivity. These values are comparable to those found in ferroelectric fluids, even though the mixture itself does not have full ferroelectric properties. Instead, it can be described as superparaelectric. Understanding the specific dielectric modes and the phenomenon of superparaelectricity allows us to design stable, high-performance materials that respond quickly to an electric field.

The work is supported by The National Science Centre grant 2025/57/B/ST5/00509.

Liquid crystals (LCs) exhibit anisotropic optical and dielectric properties, allowing them to effectively manipulate light by changing the orientation of the long axes of the molecules (the n-director) under the influence of an electric field. This makes LCs unique materials for photonics.
Along with the traditional switching of LC states, in which the director reorientation occurs due to the dielectric effect, there is a variant of the electric field interaction with flexoelectric polarization. The flexoelectric effect (FE) in liquid crystals, first theoretically predicted in 1969 by Meyer [1], arises in LCs as a result of splay and bend deformations. At low values of dielectric anisotropy, the FE becomes predominant in electrically induced orientational transitions and can manifest itself as a periodic supramolecular structure or flexolattice [2, 3].
In this research, for the first time, periodic flexostructures are investigated using planar interdigital electrodes. A nonuniform electric field generated by such an electrode system leads to the formation of modulated flexoelectric structures in the above-electrode and interelectrode regions, with wave vectors directed perpendicular and parallel to the LC layer normal, respectively. The cycloidal director distribution arising in the interelectrode region with refractive index modulation along the normal to the LC layer leads to the appearance in the transmission spectrum of a selective reflection band. The spectral position of the band depends on the amplitude of the applied voltage and on the light incidence angle relative to LC layer normal. Numerical modeling methods were used to study in detail the LC director distributions and the spectral features of the field-induced transition.

1. Meyer R.B. Piezoelectric effects... Physical Review Letters. 1969. 22(18). 918.
2. Bobylev Y.P. et al. Threshold… JETP. 1977. 45. 195.
3. Barnik M.I., et al. Flexo-electric domains… Journal de Physique. 1978. 39(4), 417-422.

Blue Phase liquid crystals (BPLCs) offer a sophisticated 3D self-assembled scaffold for templating functional nanomaterials. This study investigates the optical coupling within BPLCs doped with Copper (Cu) nanoparticles (NPs), specifically focusing on the interference between localized plasmonic modes and the 3D photonic lattice. Using dark-field hyperspectral imaging (HSI), we resolve the far-field scattering of individual Cu NPs embedded within the BPLC matrix.

A central finding of this work is the experimental observation of Fano resonance, manifested as a distinct spectral asymmetry with a pronounced shoulder and dip—in the broad scattering profile of the Cu NPs. This spectral feature occurs precisely at the wavelength range corresponding to the narrow selective reflection peak of the BPLC lattice. We attribute this to the interference between the broad plasmonic continuum of the Cu NPs and the discrete Bragg modes of the BPLC scaffold. These results are supported by polarized optical microscopy (POM) and temperature-dependent reflection measurements, which confirm the spatial and spectral correlation between NP scattering and the BPLC’s 3D photonic bandgap. These observations are validated through a finite-element method (FEM) framework, using COMSOL Multiphysics to simulate the reflection and scattering spectra. This multimodal approach demonstrates that Cu-BPLC architectures function as tunable, hybrid metamaterials, offering a pathway for designing responsive chiro-optical devices through precision spectral engineering.

Colossal Permittivity in Ferrogenic Nematic LCs.

Yuri Panarin^1,2, Rahul Uttam², and Jagdish Vij²;

¹Dept of Electrical and Electronic Eng., TU Dublin, Ireland; ²Dept of Electronic and Electrical Eng., Trinity College Dublin, Ireland;

The long-awaited ferroelectric nematic LCs (NF) predicted more long time ago were finally discovered in 2017, independently in two different materials: RM 734 and DIO. However, the presence of spontaneous polarization did not offer any advantage for display technology. Recently we observed the colossal dielectric permittivity (CP) in non-ferroelectric materials with high dipole moment > 10 D [1]. Such permittivity exists not only in LC phases materials even in isotropic phase and was also observed in [2]. Therefore, the colossal permittivity is a property of extremely high dipole moment itself but not specific phase. Here we report the existence of such CP mode in ferroelectric materials; mixtures of WJ-16 (Hull, UK) with DIO and individual component SA-153 (Belfast, UK). Both materials show three relaxation processes, where lowest frequency process P0 is ionic mobility mode, the mid-frequency process P1 shows colossal permittivity (>= 10000) and exists in all phases including the isotropic and the last one P2 shows is typical para– ferroelectric transition. The relaxation process P1 was called as superparaelectric [1] but it exists in all phases/temperatures, so the better name is “hi-permittivity” or “hyper permittivity” mode [3]. This mode opens a new range of applications of ferrogenic liquid crystals as the working media for supercapacitors with the potential of using them in energy storage devices.

References:

[1] Yu. Panarin et al, J. Mater. Chem. C, 13, 1507 (2025). DOI: 10.1039/d4tc03561e

[2] H. Nishikawa et al., Adv. Mater. 29, 1702354 (2017).

[3] R. Uttam et al, J. Mater. Chem. C, (2026). DOI: 10.1039/d6tc00004e