Today, 3D printing is no longer only used for rapid prototyping, but also for the production of customized objects, spare parts, etc. Among the various 3D printing technologies, the fused deposition modeling (FDM) process is the most widely used due to its simplicity, the mostly nontoxic polymers, and the availability of inexpensive printers and materials. However, the printed parts often exhibit mechanical and thermal inadequacies. Space applications in particular, such as microsatellites, require stable mechanical properties under periodically strongly changing temperatures. On the other hand, microsatellites and similar space applications are an area where mostly customized parts are needed, making 3D printing very suitable for such parts. New FDM-printable polymers can help to make this technology usable for space applications. Here we investigate novel FDM filaments with and without fibrous fillers before and after cyclic temperature variations between – 40 °C and + 80 °C, similar to the situation of a microsatellite in the low Earth orbit (LEO). Dimensional stability and mechanical properties were tested before and after cyclic heat treatment, showing a wide range of elastic moduli. Maximum bending forces, deflection at maximum force and tensile strengths remained nearly unchanged for most materials after heat treatment, in contrast to previous tests with standard FDM printing materials, suggesting that most materials investigated here can be used in environments with strongly varying temperature.

Heavy metal ions are harmful to aquatic life, people, and the environment, and they have been a significant source of concern for researchers for a long time. They are a public health concern since they do not biodegrade as organic contaminants do in industrial effluents. This study uses moringa waste as a bio-sorbent to remove Cr (VI) from hydrometallurgical effluents. Cr (VI) is more harmful because of its high mobility in the environment and capacity to cause cancer in organisms. Moringa waste was pyrolyzed and modified with phosphoric acid to develop a bio-sorbent. FTIR and SEM were used to determine the surface functional groups and examine the bio-sorbent's morphology and microstructure. FTIR examination revealed the moringa waste structure’s stability and aromaticity, confirmed by peaks around 1600 cm⁻¹. Because aromatic rings contribute to a large surface area and porosity and are stable, they are important for adsorption applications. At 75 minutes of contact time with 6 pH and a 1.5g adsorbent dosage at 55 ^oC, the removal percentage was found to be 68%. Adsorption data indicated a good fit to the Langmuir isotherm model, indicating that chromium VI was covered in a monolayer on the surface of the moringa waste. It could be that the adsorption rate is affected by the amount available of sites on the bio-sorbent, as the pseudo-second-order model indicated the kinetics that followed. The thermodynamic study showed that the process is endothermic and spontaneous, hence making the application of moringa waste in wastewater treatment viable.

Introduction: The World Health Organization report from 2022 points to caries being a meaningful problem worldwide. Such a state results from poor oral hygiene, huge sugar consumption and the effect of oral bacterial metabolism. The treatment of caries is based on the removal of the affected tissue and filling the cavity with dental filling. The disadvantage of this solution is the lack of antibacterial activity of dental fillings, which may result in secondary caries. The materials used in dental fillings can be modified with compounds possessing quaternary ammonium groups to achieve microbiocidal properties.
This research aims to synthesize novel dimethacrylate monomers possessing two quaternary ammonium groups. The novelty of this study was the use of two cycloaliphatic diisocyanates in the synthesis of these compounds–isophorone diisocyanate (IPDI) and 4,4′-methylenebis(cyclohexyl isocyanate) (CHMDI).

Methods: A three-step procedure was utilized to obtain the novel monomers:
I. Transesterification of MMA;
II. N-alkylation of semi-product with 1-bromododecane;
III. Addition of a second semi-product to diisocyanate.
The chemical structures of the obtained monomers were confirmed with ¹H and ¹³C NMR and FTIR spectroscopy.

Results: The synthesis resulted in two novel monomers—QA12+IPDI and QA12+CHMDI—which are viscous, yellowish liquids. ¹H and ¹³C NMR and FTIR spectroscopy confirmed the structures of the obtained monomers.

Conclusions: The spectroscopy methods confirmed the structures of our novel monomers. Future research will be focused on the characterization of these monomers’ properties.

This paper presents a comprehensive stochastic model of the optoelectronic and photonic components of an interferometric fiber-optic gyroscope (IFOG), which plays a critical role in inertial navigation systems, especially for aerospace applications. The model accounts for various noise sources and disturbances, including power drift, the Kerr effect, and electronic noise generated by the photodetector and transimpedance amplifier. These elements are crucial for accurately simulating the real-world behavior of the IFOG system. Experimental validation was carried out using a prototype integrated from commercially available components, with a 500-meter fiber coil as the sensing element.

The experimental results showed strong agreement with the numerically simulated waveforms, demonstrating the model's ability to predict the IFOG’s behavior under different operating conditions. The noise sources were modeled using Gaussian and Poisson distributions, capturing the stochastic nature of the disturbances. The Kerr effect, in particular, was identified as a significant influence but was mitigated by employing a broadband light source.

This validated model offers a valuable tool for the development of more advanced IFOG systems, including those that integrate readout electronics. It enables better interpretation of experimental data and paves the way for future improvements in precision, making it suitable for applications requiring highly accurate angular velocity measurements.

In this work, we studied the electrical and thermal properties of graphene nanoplatelet (GNP)/epoxy nanocomposites in terms of different variables, such as GNP type or dispersion time. The relationship between these parameters and the electrical and thermal properties of the samples was analyzed, focusing on samples over the percolation threshold (which is around 7 %wt). The best results were observed with 10–12% loading and a higher surface area, as the optimal electrical conductivity and an increase on the shielding effectiveness were achieved in the GHz range. Several characterization techniques, such as Raman spectroscopy and X-ray diffraction, were employed to analyze the GNPs after the sonication process, providing valuable information about the aspect ratio of the GNPs. The electromagnetic interference shielding (EMI) was studied between 100 MHz and 4 GHz, showing an increase in value with increasing GNP content, achieving a maximum of nearly 5 dB at 2 GHz. The influence of sonication on the results was analyzed, as sonication affects the morphological characteristics of nanoplatelets, introducing defects and modifying their aspect ratio. This shows the importance of the proper selection of sonication time to achieve the best dispersion state of the reinforcement within the epoxy matrix to achieve the maximum electrical conductivity and, thus, the optimal shielding performance.

The intake of drugs, their absorption in the body, their removal, and various side effects are factors that should be considered in drug design. Here, in silico tools act as virtual shortcuts assisting in the prediction of several important physicochemical properties like molecular weight, polar surface area (PSA), molecular flexibility, etc., to evaluate probable drug leads as potential drug candidates. Moreover, these tools also play an important role in the prediction of the bioactivity score of a probable drug lead against various human receptors. This paper presents a virtual combinatorial library of selected thiosmeicarbazone ligands and their metal complexes. Different properties, like physicochemical properties, bioactivity score, and absorption, distribution, metabolism, excretion, and toxicity (ADMET) parameters were assessed. The structures of ligands and complexes were drawn and downloaded in PDB format using ChemDraw Ultra 12.0. Physicochemical parameters were calculated using online software, viz., Molinspiration and SwissADME, and ADMET properties were calculated using admetSAR (2.0). Molecular docking was performed using PyRx Python Prescription 0.8. with two proteins, namely Transforming Growth Factor Beta (Tgf- β) and Janus Kinase. Transforming Growth Factor Beta (Tgf- β) and Janus Kinase are some of the cytokines involved in cell development, proliferation, and death. Salicyldehyde thiosemicarbazone, acenaphthenequinone thiosemicarbazone, and 2-chloronicotinic thiosemicarbazone and their virtually designed complexes exhibited appreciable in silico results. Most of the ligands and complexes had good bioactivity values against all the biological targets.

The urgent need to address new health issues and enhance the effectiveness of treatment for a wide range of illnesses motivates the search for novel therapeutic agents as a current task in medicinal chemistry. Irritable bowel syndrome (IBS) is a multifactorial disorder characterized by altered intestinal motility, visceral hypersensitivity, dysfunction of the gut-brain axis. The nanoparticle system is one of the best ways to provide medication in a controlled manner. This study aims to develop drug-loaded silver nanoparticles (AgNPs) with mebeverine to improve the treatment of IBS.

A green, glucose-assisted method for the rapid synthesis and stabilization of AgNPs as a drug-delivery system is presented. The synthesized AgNPs were characterized by their UV-Vis spectra, TEM, zeta potential, and drug release. To assess their pharmacological potential, a series of ex vivo and in vitro experiments were conducted.

The mebeverine-based AgNPs were designed to relax smooth muscle tissue, providing a novel treatment option for IBS patients. Biological experiments showed that drug-loaded AgNPs have better spasmolytic activity compared to mebeverine.

In in vitro and ex vivo experimental models of inflammation, the nanoparticles significantly inhibited the production of pro-inflammatory cytokines and other mediators of inflammation. This activity suggests that synthesized AgNPs could be effective in treating chronic inflammatory conditions such as IBS, rheumatoid arthritis, and other autoimmune disorders.

Based on the results, synthesized AgNPs might be a promising medication delivery system and a useful treatment option for IBS. Our research into the synthesis and biological evaluation of drug-loaded AgNPs reveals their potential as novel therapeutic agents, capable of modulating multiple inflammation pathways. The promising results achieved so far underscore the importance of continued exploration and development in this area.

Acknowledgements: This study is part of Scientific Project KP-06-H73/11 of the National Fund for Scientific Research in Bulgaria, National Program for Basic Research Projects 2023.

The electrical and optical properties of various types of perovskite halides are dependent on the atomic compositions of the compounds, and their photovoltaic properties and stability are also affected by the interfacial structures of the devices. The aim of the present work was to fabricate and characterize guanidinium [C(NH₂)₃, GA]-, ethylammonium (CH₃CH₂NH₃, EA)-, and rubidium (Rb)-added CH₃NH₃PbI₃ (MAPbI₃) solar cells, which were passivated with decaphenylcyclopentasilane (DPPS) and GA. First-principles calculations on the proposed mixed-cation halides clarified the electronic structures, which were compared with experimental data. The lattice constants of GA/EA-added perovskites increased through the growth of perovskite crystals aged at ~22°C, which caused an increase in photoconversion efficiency. The GA/EA co-addition also improved their photovoltaic properties in an indoor light environment using a white-color LED. The surface passivation of MAPbI₃ using GA and DPPS decreased carrier traps in the perovskite crystal, and the photovoltaic properties were improved. Energy band structures and the partial density of states were investigated in the GA-, EA-, and Rb-modified perovskite compounds using first-principles calculations. The calculations showed that the total energies were reduced by adding GA, EA, or Rb to the perovskites. The bandgap energies were also decreased, which could lead to an increase in current density.

Methylammonium lead iodide (MAPbI₃) perovskite solar cells using metal phthalocyanines (MPc) and naphthalocyanines (MNc) as hole transport materials for improving photovoltaic performance with long-term stability have been characterized. The purpose of this study was to fabricate and characterize MAPbI₃ perovskite solar cells using MPc and MNc as hole-transporting layers for improved photovoltaic and optical properties with stability. We characterized the photovoltaic characteristics, morphology, crystallinity and electronic structures of the MAPbI₃ perovskite solar cells using nickel phthalocyanine (NiPc). The photovoltaic performance reached the maximum values of conversion efficiency (η) at 13.4 %. The behavior was based on the surface morphology, crystal orientation and near-defect passivation of the perovskite crystal. The surface passivation of NiPc supported crystal growth, improving carrier diffusion with the suppression of near-defect carrier recombination. The photovoltaic mechanism was discussed using the energy diagram of the perovskite solar cell. The insertion of NiPc optimized the energy levels near the highest occupied molecular orbital while adjusting the valence band levels and supporting the charge transfer from the perovskite layer to the hole-transporting layer. Simulation using SCAPS-1D programs predicted the photovoltaic characteristics of the perovskite layer in terms of the hole-transporting thickness and trap density. The photovoltaic performance was optimized based on the results of the simulation and experiments.

Graphene or carbon nanowalls, graphene sheets, and graphene nanoflakes are other names for vertical graphene (VG), a three-dimensional form of graphene. Compared to conventional horizontally oriented or randomly arranged graphene, the interest in vertically oriented graphene can be attributed to its unique geometry and open three-dimensional lattice, which allows easier access to the graphene edges, higher surface-to-volume ratio, high electrochemical activity, and electrical conductivity. The electrochemical properties of VG can be improved by incorporating nanoparticles that can change the major type of charge carriers, increase the specific surface and prevent the aggregation of graphene sheets. In this paper, we established a process for synthesising VG-based nanocomposites by treating graphene in an acid solution and then decorating the sheets with gold nanoparticles. The vertical graphene obtained by the chemical vapour deposition process on the Si/SiO₂ substrate is subjected to a treatment with H₂SO₄ and HNO₃ to improve the wetting capacity. The anchoring of the metallic nanoparticles is carried out through an ex-situ process, which involves 2 stages, in the first part the synthesis of the metallic nanoparticles is performed, and in the second step, the GV substrate is immersed in the gold NPs solution. Gold nanoparticles are obtained using chloroauric acid, as a precursor, and trisodium citrate, as both reducing agent and electrostatic stabilizer of the nanoparticles to avoid agglomeration. Using SEM microscopy, the shape, size, and distribution of metal nanoparticles inside the graphene were evaluated. Spectroscopy was used for the structural analysis, and goniometric studies revealed the wetting and percolation capacity of the obtained materials. The application capacity was demonstrated by cyclic voltammetry.

Acknowledgements: This work was supported by the Core Program within the National Research Development and Innovation Plan 2022-2027, carried out with the support of MCID, project no. 2307 (µNanoEl).