Synthesis and properties of lanthanum hexaaluminate ceramic La1−xCaxAl11−y−zMgyTizO18

The aim of the present work is to obtain ceramic materials with a hexagonal structure and high density, hardness and mechanical strength at lower synthesis temperature. Ceramic samples with nominal composition La_1−xCa_xAl_11−y−zMg_yTi_zO₁₈ (x=0–1; y=0–3; z=0–3,5) are prepared. The samples are sintered at temperature 1500 °C by one-stage and two-stage ceramic technology. By X-ray diffraction and scanning electron microscopy, predominant phase LaAl₁₁O₁₈ and second phases LaAlO₃ and -Al₂O₃ are identified. Ceramic materials are characterized with high physico-mechanical properties and may be find application for production of mill bodies and materials for immobilization of nuclear waste.     

Synthesis and characterization of a new family of photoactive liquid crystalline polyesters based on α‐methylstilbene

A liquid crystal polyester and two liquid crystal copolyesters containing α‐methylstilbene moieties and aliphatic or aromatic spacers in the backbone were synthesized in good yields, with the aim of using them for photosensitive microcapsule preparation. The synthesized polymers were fully characterized with respect to thermal stability, type of mesophase, molecular weight and E–Z photoisomerization. Combination of monomers with different structures allowed adjustment of the polymer characteristics such as degree of crystallinity and glass transition temperature, as verified using X‐ray diffraction, polarized optical microscopy and differential scanning calorimetry. Quantitative ¹H NMR and UV‐visible experiments were performed in order to investigate E–Z photoisomerization after photoirradiation at 364 nm. Finally, a membrane based on one of these polymers was prepared and it was found that its wettability increased on photoirradiation. © 2013 Society of Chemical Industry     

Visible Light Communications (VLC) for Ambient Assisted Living

With the advent of high efficacy light emitting diode directional lamps as a key component in focal lighting, new possibilities emerge for re-designing the smart home scenario. A smart home scenario is characterized by enabled intelligent interworking of various wireless and wired technologies to provide inhabitants with ease of use of appliances, while creating a personalized and safe ambience space. More and more high and low data rate circulates within the indoor ambient space (e.g., home, hospitals, offices). Although, unlicensed technologies, such as wireless local area networks can take upon part of the indoor traffic, the ever increasing demand for such data, and users, calls for either use of licensed or novel unlicensed wireless communication technologies as part of the smart home enablers. This paper focuses on the potentials of visible light communications (VLCs), jointly with radio and fiber communications, to support very dense low and high data rate connectivity, while enabling deployment of secure-sensitive indoor applications, including indoor tracking and localization. The paper proposes a scenario for integrating VLC into the smart home scenario and a conceptual supporting architecture for its deployment. Further, the technical challenges and possible roadmap for the actual deployment are analyzed for the particular case of an eHealth scenario where the utilization of VLC technology is the enabler of the cost-efficient rollout of the required infrastructure and thus the game-changer in a multi-billion eHealth niche that is seeking for cost affordable solutions.     

Nanoparticles in low melting amorphous selenite materials

The aim of the present investigation is to establish the appropriate routе of nanoparticles formation during heat treatment of selected selenite glasses. Multicomponent compositions containing SeO₂, V₂O₅, TeO₂, MoO₃, ZnO and Ag₂O have been selected. Different preparation methods of the initial glass samples have been combined with heat treatment to influence the glass microstructure and formation of different types of microheterogeneites. TEM and SEM have been used to prove the formation of nanosized particles, randomly distributed in the amorphous matrix volume. Samples containing above 50 wt% Ag₂O show the formation of elementary silver with an average particle size of 50–100 nm. Glass-ceramic materials have been obtained after a long thermal treatment. The main crystal phases detected are Ag₂SeO₃, Ag₂TeO₃ and TeO₂.     

Curcumin and the cellular stress response in free radical-related diseases

Free radicals play a main pathogenic role in several human diseases such as neurodegenerative disorders, diabetes, and cancer. Although there has been progress in treatment of these diseases, the development of important side effects may complicate the therapeutic course. Curcumin, a well known spice commonly used in India to make foods colored and flavored, is also used in traditional medicine to treat mild or moderate human diseases. In the recent years, a growing body of literature has unraveled the antioxidant, anticarcinogenic, and antinfectious activity of curcumin based on the ability of this compound to regulate a number of cellular signal transduction pathways. These promising data obtained in vitro are now being translated to the clinic and more than ten clinical trials are currently ongoing worldwide. This review outlines the biological activities of curcumin and discusses its potential use in the prevention and treatment of human diseases.     

Fiber formation and properties of polyester/lignin blends

Thermotropic liquid crystalline polyesters with varied chemical structure are synthesized by melt transesterification polycondensation. They are employed as matrix for blends with lignin materials to obtain melt-spinnable precursors for carbon fibers. The lignin samples are carefully purified by fractionation, enzymatic removal of reducing sugars, and subsequent modification of the terminal OH groups. Effective melt blending is achieved with liquid-crystalline aromatic–aliphatic polyesters having melting ranges that match the softening temperature of the lignin fractions, which is necessary to prevent thermal decomposition of the lignin. Polyester/lignin blends are partially compatibilized, phase-separated materials. The polyester/lignin materials are melt-spun successfully. The fiber properties depend on the lignin purification process. X-ray scattering reveals that orientation in lignin-containing fibers is maintained. First experiments show that the fibers can be converted successfully to carbon fibers by thermal annealing procedures. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48257.     

Light‐Driven Proton Transfer for Cyclic and Temporal Switching of Enzymatic Nanoreactors

Temporal activation of biological processes by visible light and subsequent return to an inactive state in the absence of light is an essential characteristic of photoreceptor cells. Inspired by these phenomena, light‐responsive materials are very attractive due to the high spatiotemporal control of light irradiation, with light being able to precisely orchestrate processes repeatedly over many cycles. Herein, it is reported that light‐driven proton transfer triggered by a merocyanine‐based photoacid can be used to modulate the permeability of pH‐responsive polymersomes through cyclic, temporally controlled protonation and deprotonation of the polymersome membrane. The membranes can undergo repeated light‐driven swelling–contraction cycles without losing functional effectiveness. When applied to enzyme loaded‐nanoreactors, this membrane responsiveness is used for the reversible control of enzymatic reactions. This combination of the merocyanine‐based photoacid and pH‐switchable nanoreactors results in rapidly responding and versatile supramolecular systems successfully used to switch enzymatic reactions ON and OFF on demand.