PETG as an Alternative Material for the Production of Drone Spare Parts.

Material selection is the main challenge in the drone industry. In this study, hardness, abrasive wear, impact resistance, tensile strength, and durability (frost resistance and accelerated ageing) were identified as important characteristics of drone materials. The additive manufacturing technology was used to produce the drone leg specimens and prototype.

Bio-Epoxy Resins Based on Lignin and Tannic Acids as Wood Adhesives-Characterization and Bonding Properties.

The possibility of producing and designing bio-epoxides based on the natural polyphenol lignin/epoxidized lignin and tannic acids for application as wood adhesives is presented in this work. Lignin and tannic acids contain numerous reactive hydroxyl phenolic moieties capable of being efficiently involved in the reaction with commercial epoxy resins as a substitute for commercial, non-environmentally friendly, toxic amine-based hardeners. Furthermore, lignin was epoxidized in order to obtain an epoxy lignin that can be a replacement for diglycidyl ether bisphenol A (DGEBA).

Polymethylenetetrazole: Synthesis, Characterization, and Energetic Properties.

The tetrazole moiety remains one of the most interesting scaffolds in the development of new high-energy density materials (HEDMs) because of its desired characteristics, such as high nitrogen content and heat of formation (HOF). The combination of several heterocycles with high HOF seems to be a promising strategy for obtaining energetic materials with superior properties. Herein, we report the synthesis and characterization of a tetrazole polymer, polymethylenetetrazole (PMT), as a potential HEDM.

Unsaturated polyester resin based composites: A case study of lignin valorisation.

Materials from green resources boast a low carbon footprint, forming the foundation of the circular economy approach in materials science. Thus, in this study, waste poly(ethylene terephthalate) (PET) was subjected to depolymerization using propylene glycol (PG), and subsequent polycondensation with bio-based maleic anhydride (MA) produced unsaturated polyester resin (b-UPR). Bio-derived acryloyl-modified Kraft lignin (KL-A) served as a vinyl reactive filler in the b-UPR matrix to create b-UPR/KL-A composites.

Effects of Synthesis Parameters on Structure and Antimicrobial Properties of Bacterial Cellulose/Hydroxyapatite/TiO Polymer-Ceramic Composite Material.

Bacterial cellulose (BC) is a highly pure polysaccharide biopolymer that can be produced by various bacterial genera. Even though BC lacks functional properties, its porosity, three-dimensional network, and high specific surface area make it a suitable carrier for functional composite materials. In the present study, BC-producing bacteria were isolated from kombucha beverage and identified using a molecular method.

Synthesis, Characterization and Application of Biobased Unsaturated Polyester Resin Reinforced with Unmodified/Modified Biosilica Nanoparticles.

This paper presents sustainable technology for environmentally friendly composite production. Biobased unsaturated polyester resin (b-UPR), synthesized from waste polyethylene terephthalate (PET) glycosylate and renewable origin maleic anhydride (MAnh) and propylene glycol (PG), was reinforced with unmodified and vinyl-modified biosilica nanoparticles obtained from rice husk. The structural and morphological properties of the obtained particles, b-UPR, as well as composites, were characterized by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques.

Effect of Temperature on S32750 Duplex Steel Welded Joint Impact Toughness.

The search for alternative materials that can be used for parts of aircraft hydraulic systems has led to the idea of applying S32750 duplex steel for this purpose. This steel is mainly used in the oil and gas, chemical, and food industries. The reasons for this lie in this material's exceptional welding, mechanical, and corrosion resistance properties.

How Well Do Our Adsorbents Actually Perform?-The Case of Dimethoate Removal Using Viscose Fiber-Derived Carbons.

Growing pollution is making it necessary to find new strategies and materials for the removal of undesired compounds from the environment. Adsorption is still one of the simplest and most efficient routes for the remediation of air, soil, and water. However, the choice of adsorbent for a given application ultimately depends on its performance assessment results.

Emergency unmanned airborne spectrometric (HPGe) monitoring system.

After a nuclear or radiation event, emergency responders and radiation protection authorities need quick and credible information based on reliable accident and post-accident radiological data. However, risks to people in the vicinity of the source pose serious measurement challenges. Many problems could be solved by unmanned airborne monitoring systems, but the current ones are mostly based on non-spectrometric detectors carried by drones with low bearing, short flying range and flight time.

Lignin based microspheres for effective dyes removal: Design, synthesis and adsorption mechanism supported with theoretical study.

Multifunctional lignin bio-based adsorbent, b-LMS, was obtained via inverse copolymerization in the suspension of acryloyl modified kraft lignin (KL-AA) and bio-based trimethylolpropane triacrylate (bio-TMPTA). Morphological and structural characterization of KL-AA and b-LMS was performed using BET, FTIR, Raman, NMR, TGA, SEM, and XPS techniques. The b-LMS microspheres with 253 ± 42 μm diameters, 69.

A Multigraph-Defined Distribution Function in a Simulation Model of a Communication Network.

We presented a method based on multigraphs to mathematically define a distribution function in time for the generation of data exchange in a special-purpose communication network. This is needed for the modeling and design of communication networks (CNs) consisting of integrated telecommunications and computer networks (ITCN). Simulation models require a precise definition of network traffic communication.

Determination of Mechanical Properties of Epoxy Composite Materials Reinforced with Silicate Nanofillers Using Digital Image Correlation (DIC).

In this study, silicate nanofillers; dicalcium silicate, magnesium silicate, tricalcium silicate, and wollastonite; were synthesized using four different methods and incorporated into the epoxy resin to improve its mechanical properties. Characterization of the newly synthesized nanofillers was performed using Fourier-transformation infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The purpose of this study was to analyze newly developed composite materials reinforced with silicate nanoparticles utilizing tensile testing and a full-field non-contact 3D Digital Image Correlation (DIC) method.

The Effect of Material Heterogeneity and Temperature on Impact Toughness and Fracture Resistance of SA-387 Gr. 91 Welded Joints.

This paper presents the analysis of the behavior of welded joints made of 9-12% Cr-Mo steel SA-387 Gr. 91. The successful application of this steel depends not only on the base metal's (BM) properties but even more on heat-affected-zone (HAZ) and weld metal (WM), both at room and at operating temperature.

Numerical Investigation into In-Plane Crushing of Tube-Reinforced Damaged 5052 Aerospace Grade Aluminum Alloy Honeycomb Panels.

This paper aims to investigate the crashworthiness performance degradation of a damaged 5052 aluminum honeycomb panels under in-plane uniaxial quasi-static compression and the possibility of improving it using reinforcement tubes. The in-plane crushing behaviors and energy absorption capacities of the intact, damaged, and tube-reinforced damaged panels with different damage sizes in both X and X directions are numerically simulated by using the nonlinear FE method Abaqus/Explicit, and the crashworthiness performances are compared with each other. The validation of finite element model involves comparing the obtained simulation results with theoretical and experimental ones.

Numerical and Experimental Investigations of Fracture Behaviour of Welded Joints with Multiple Defects.

Current standards related to welded joint defects (EN ISO 5817) only consider individual cases (i.e., single defect in a welded joint).

The characterization and pollution status of the surface sediment in the Boka Kotorska Bay, Montenegro.

Surface sediments collected from twelve stations in the Boka Kotorska Bay were analyzed for the level and distribution of twenty-six elements and ten oxides, grain sizes, organic matter, and carbonate content. Potentially toxic elements (Al, Fe, Mn, Cr, Zn, Ni, Cu, Pb, As, Co, U) were determined to assess the contamination status and potential environmental risk according to the single-element indices (enrichment factor (EF), geoaccumulation index (Igeo), contamination factor (CF)), and combined index (pollution load index (PLI)). The single-element indices EF and CF revealed that the surface marine sediment was moderately polluted with Pb, Cu, and Cr, while Igeo indicated moderate pollution with Ni > Cr > Zn > Cu > As and moderate to heavy pollution with Pb, as a result of the anthropogenic factors.

Spatial and temporal distribution of pollution indices in marine surface sediments-a chemometric approach.

Concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, and Fe measured at forty locations in the Boka Kotorska Bay were used to monitor the spatial and temporal quality of sediment and to assess surface sediment contamination over the last 15 years. This ecological geochemistry assessment was made using two classes of pollution indices: single indices concerning the investigated elements (contamination factor (Cf)) and integrated indices concerning the locations (pollution load index (PLI), potential ecological risk index (RI), mean effects range median quotient (MERMQ), toxic risk index (TRI), contamination severity index (CSI)). The distribution of all indices was geostatistically mapped and several hotspots were identified.

Influence of Welding Speed on Fracture Toughness of Friction Stir Welded AA2024-T351 Joints.

In order to ensure a quality welded joint, and thus safe operation and high reliability of the welded part or structure achieved by friction stir welding, it is necessary to select the optimal welding parameters. The parameters of friction stir welding significantly affect the structure of the welded joint, and thus the mechanical properties of the welded joint. Investigation of the influence of friction stir welding parameters was performed on 6-mm thick plates of aluminum alloy AA2024 T351.

A Symbolic Encapsulation Point as Tool for 5G Wideband Channel Cross-Layer Modeling.

Considering that networks based on New Radio (NR) technology are oriented to provide services of desired quality (QoS), it becomes questionable how to model and predict targeted QoS values, especially if the physical channel is dynamically changing. In order to overcome mobility issues, we aim to support the evaluation of second-order statistics of signal, namely level-crossing rate (LCR) and average fade duration (AFD) that is missing in general channel 5G models. Presenting results from our symbolic encapsulation point 5G (SEP5G) additional tool, we fill this gap and motivate further extensions on current general channel 5G.

Molecular recognition of acetylcholinesterase and its subnanomolar reversible inhibitor: a molecular simulations study.

Recently, we designed and synthesized a subnanomolar, reversible, dual-binding site acetylcholinesterase (AChE) inhibitor which consists of the tacrine and aroylacrylic acid phenylamide moieties, mutually linked by eight methylene units. To further investigate the process of the molecular recognition between the AChE and its inhibitor, we performed six unconstrained molecular dynamics (MD) simulations, where the compound in three possible protonation states was placed inside binding sites of two available AChE crystal structures. In all six MD trajectories, the ligand generally occupied similar space inside the AChE active site, but the pattern of the interactions between the ligand functional groups and the amino acid residues was significantly different and highly dependent upon the crystal structure used to generate initial systems for simulation.

Amino-modified kraft lignin microspheres as a support for enzyme immobilization.

In this research, it has been demonstrated that amino-modified microspheres (A-LMS) based on bio-waste derived material, such as kraft lignin, have good prospects in usage as a support for enzyme immobilization, since active biocatalyst systems were prepared by immobilizing β-galactosidase from and laccase from expressed in (Novozym® 51003) onto A-LMS. Two types of A-LMS were investigated, with different emulsifier concentrations (5 wt% and 10 wt%), and microspheres produced using 5 wt% of emulsifier (A-LMS_5) showed adequate pore shape, size and distribution for enzyme attachment. The type of interactions formed between enzymes (β-galactosidase and laccase) and A-LMS_5 microspheres demonstrated that β-galactosidase is predominantly attached electrostatic interactions while attachment of laccase is equally governed by electrostatic and hydrophobic interactions.

The in vitro protective effects of the three novel nanomolar reversible inhibitors of human cholinesterases against irreversible inhibition by organophosphorous chemical warfare agents.

Acetylcholinesterase (AChE) is an enzyme which terminates the cholinergic neurotransmission, by hydrolyzing acetylcholine at the nerve and nerve-muscle junctions. The reversible inhibition of AChE was suggested as the pre-treatment option of the intoxications caused by nerve agents. Based on our derived 3D-QSAR model for the reversible AChE inhibitors, we designed and synthesized three novel compounds 8-10, joining the tacrine and aroylacrylic acid phenylamide moieties, with a longer methylene chain to target two distinct, toplogically separated anionic areas on the AChE.

Arsenic removal by copper-impregnated natural mineral tufa part II: a kinetics and column adsorption study.

This batch and column kinetics study of arsenic removal utilized copper-impregnated natural mineral tufa (T-Cu(A-C)) under three ranges of particle size. Non-competitive kinetic data fitted by the Weber-Morris model and the single resistance mass transfer model, i.e.

Photonic structures improve radiative heat exchange of Rosalia alpina (Coleoptera: Cerambycidae).

The insect cuticle serves a multitude of purposes, including: mechanical and thermal protection, water-repelling, acoustic signal absorption and coloration. The influence of cuticular structures on infrared radiation exchange and thermal balance is still largely unexplored. Here we report on the micro- and nanostructured setae covering the elytra of the longicorn beetle Rosalia alpina (Linnaeus, 1758) (Coleoptera: Cerambycidae) that help the insect to survive in hot, summer environments.