The common and established two-step carbonization technology for obtaining activated carbonaceous material does not produce such valuable material in high yield. Hence, one of the directions for improving its manufacturing technology is working out protocols to unify the carbonization and activation processes. The present study aims to show the development of a combined, single-stage, highly efficient, ecologically and economically profitable technology and determine the area of the usage of the obtained product.

The procedure is based on an invention that provides sorbents with a highly developed surface, as a result of the introduction of a cheap reagent into the process of thermochemical conversion of plastics and cellulose-containing waste (National Intellectual Property Center of Georgia - "Sakpatenti" under the patent: P 2021 7309 B).

A wide range of raw materials (hazelnut and walnut shells, nectarine and peach kernels, wood sawdust, etc.) can be directly loaded into the reactor without pretreatment. It is then inflated with inert gas and processed in an oxygen-free area. The temperature in the reactor rises at a pre-selected, defined speed until the final temperature is reached; simultaneously, steamed water is supplied at a certain (ml/h) rate.

The reactor is equipped with an automatized device so the process can be carried out in adjustable modes (temperature, reagent supply rate, reactor heating rate, etc.).

This technology allows the realization of three products, carbonaceous material, liquid phase (generated from the initial material and a certain amount of unprocessed reagent), and gaseous substances in the form of flammable gases that can serve as an energy source for the progression or reaction when cycled back into the process.

The quality requirements for activated carbonaceous material, depending on the purpose of the target product (medicine, water/air purifier, etc.), can be determined by varying the set of desirable major parameters for the reactor.

This work was supported by Shota Rustaveli National Science Foundation of Georgia, grant number FR21- 12546

Ultra-thin (20 ㎛) silicon strain gauges were fabricated with a silicon-on-insulator (SOI) wafer by a wet etching process. A buffered oxide etchant (BOE, NH₄F: HF =6:1) solution was used for the wet etching process in which the operating temperature was 50℃. Photoresist was deposited on the upper side of the SOI wafer as a passivation layer to minimize strain gauge damage by the chemical etchants. Small amounts of octylamine and 1-octanol were added to BOE solution to improve surface wettability and SiO₂/Si selectivity. The fabricated strain gauges were attached to the pressure diaphragm and the performance of the strain gauges was investigated by measuring with the hydraulic pressure system. The resistance changed linearly with tensile and compressive strains. Maximum values of non-linearity, hysteresis, thermal coefficient of resistance (TCR) and sensitivity were -0.341%, 0.909%, 4,128 ppm/℃ and 34.22 mV/V, respectively. The fabricated strain gauges might be well applicable to hydrogen pressure sensors detectable on a high pressure range.

In the context of reducing the environmental footprint, the composite materials industry is in pursuit of replacing, partially or totally, the synthetic raw materials with renewable sustainable ones. In recent years, success has proven to come from using vegetable fibres for reinforcement. In Western Europe, multiple enterprises took part in the commercialisation of vegetable fibres destined for composite materials, and this opportunity has arisen from the reduced demand in the habitual textile industry. In Romania, such a sector is not established, even though a similar development potential exists due to the reduced demand of fibres for textiles during the last 30 years and the appropriate climate conditions for cultivation. Therefore, it is worth looking at the reasons behind this absence, and investigating the current economic context can allow for competitive prices. This study followed this line of investigation by analyzing the mechanical properties. Two types of fibres were investigated, hemp and flax, cultivated in Romania. The literature shows them as being the most prominent for composite reinforcement and both have a long history of cultivation on the Romanian territory. Tensile tests were used for this reason, and the tensile stress--strain curves revealed the Young modulus and strength at failure for the two types of fibres. Samples of several lengths were analysed, as it has been noted to be an important factor of influence. Due to the high dispersion of experimental results, characteristic to reinforcement fibres, a statistical approach was used. Several types of stress--strain curves were determined, with bi-linear or tri-linear evolutions, all in the limits of what is available in the literature regarding the two types of fibres.

Aluminosilicate binders such as Portland cement or alkali-activated materials (slag and fly ash) are generally considered electrical insulators. In order to decrease their electrical resistance, electrically conductive fillers are added. This brings new application possibilities such as the self-sensing and self-monitoring of smart structures. Three different aluminosilicate composites with the same amount of fine graphite filler (6% with respect to the basic aluminosilicate raw material) were tested for resistance- as well as capacitance-based self-sensing properties in this study. Portland cement and two different alkali-activated binders were used as basic matrices for the conductive composites. The composites were tested for self-sensing properties in repeated compression in the elastic area, static mechanical properties and microstructure by means of scanning electron microscopy and mercury intrusion porosimetry. The results showed that alkali-activated materials are less stiff compared to the Portland cement composite but they provide better self-sensing properties regardless of measured electrical parameter. The best self-sensing properties were achieved with the blended alkali-activated slag/fly ash composite. On the other hand, this composite showed the worst mechanical properties, which was mainly due to the increased porosity in the range of large capillary pores (1–10 μm).

Biocompatible polymers, like high-molecular-weight polyethylene (UHMWPE), can be used in joint prostheses. However, even with good quality of the material, problems such as wear due to abrasion form polymer fragments, causing cell apoptosis and loss of the prosthesis. Modifying materials like UHMWPE with nanocomposites is possible to give new properties to the prosthesis, like better mechanical and antimicrobial effects, increasing the useful life of the device and avoiding stress for the patient in them having to have their prosthesis changed sometime after having it placed. Graphene is a nanomaterial that can be incorporated into prostheses to give them greater resistance and antimicrobial activity upon contact, preventing loss of the prosthesis. The objective of this work is to evaluate the effect of graphene when incorporated into a jaw joint prosthesis, evaluating the biocompatibility, antimicrobial and mechanical resistance effects. Graphene was incorporated into the prosthesis by thermopressing, obtaining two prostheses: one with UHWMPE and the other with UHWMPE + graphene. The production process is new, so a patent has been filed for this new process (BR10202400456). The results from the TGA show a lower onset temperature of the prosthesis without graphene, in addition to it showing antimicrobial properties in microbiology tests. Characterization tests such as Raman spectroscopy, XPS and SEM were also carried out, and mechanical tests showed that the new prosthesis with graphene incorporated endured a force higher than usual before breaking. Therefore, a new prosthesis with graphene was successfully obtained through a new process, and further tests will be used to check the regulatory aspects for its application in the industry.

The use of different industrial alkaline waste as secondary raw materials (SCMs) is a frequent practice in the cement industry as a source of cements with a lower carbon footprint and thus compliant with the climate neutrality route planned for the year 2050. The present work focuses on the study of alkaline waste from RCDs (fine concrete fraction <5mm, CDW-C), white ladle furnace slag (LFS) and forest biomass ashes (BA). In all wastes, a complete chemical, physical and mineralogical characterization has been carried out using different techniques such as FRX, XRD-Rietveld, SEM/EDX, FTIR, TG/DTA and laser granulometry analysis, in addition to thermodynamically modeling the pozzolanic reaction in the system pozzolan/lime of each of three wastes studied. The binary cement pastes made with partial substitutions of 7% and 20% waste were cured for 28 days under water, and the mineralogical phases formed were analyzed with respect to a reference paste. This analysis has allowed us to highlight that the neophases are related to the nature of the alkaline residue. Generally, in LFS cement paste, hydrogarnet is the stable phase, while in BA and CDW-C pastes, ettringite and C-S-H and C-(A)-S-H gels are the last phases.

Acknowledgments: This research was funded by the Ministry of Science and Innovation of Spain, AEI and FEDER Funds (MICINN, PID2021-122390OB-C21).

Currently, waste management is a major problem around the world. During the past two decades, scientists, regulatory agencies, and the European Commission (2000/60/EC) have acknowledged pharmaceuticals as an emerging global environmental problem [1]. It has even been shown that during pandemics, prescribed or uncontrolled consumption of drugs, along with general pathogen contamination, led to an unwelcome increase in their quantity in water systems and soil. Thus, offering a proper management for the processing of emerging waste is a very overdue.

The main purpose of the present work is to provide information on the sorption properties of carbonaceous materials obtained from hazelnut/walnut shells and nectarine kernel using a technology developed [2] at Ivane Javakhishvili Tbilisi State University Institute of Inorganic Chemistry and Electrochemistry, as well as to show the possibility of their use for purifying water polluted by pharmaceuticals (paracetamol) from model solutions and microbial pathogens from landfill leachate water.

We performed an assessment of the adsorptive properties of obtained carbonaceous materials and their efficiency related to the initial concentration of paracetamol in static conditions vs. adsorbent dose/size, contact time, pH, and microbial pathogens vs. adsorbent dose and size in dynamic conditions. which showed the following:

• The maximum amount of paracetamol that can be bound by 0.1 grams of sorbent in a 50 ml solution is 98.55% (in the first 30 minutes).
• An increase in the amount of adsorbents was reciprocated in the value of the sorption efficiency (100%) by largely improving it.
• The adsorption process was well described by the Langmuir and Freundlich isotherm models.
• The optimal size of sorbent particles for the better sorption of microbiological agents (60nm -1000 µm) was determined.
• The maximum selectivity for all studied pollutants was shown by carbonaceous material obtained from hazelnut shells _~ 70-99%.

1. Sustainable Remediation Technologies for Emerging Pollutants in Aqueous Environment 2024, Pages 79-109. https://doi.org/10.1016/B978-0-443-18618-9.00011-5

2.Patent P 2021 7309 B

The physical and chemical properties of Prussian blue analogs (PBAs) have increasingly attracted the attention of the scientific community due to its promising applications in electrochemical sensing, electrochromic devices, batteries, supercapacitors, and magnetic/ photomagnetic systems, among others. Recently, we have studied the resistive switching effect in electrodeposited Prussian blue (PB) [1], Prussian white (PW) [2], and Na-based Prussian blue films [3] enabling potential applications in the field of memristors. However, the potential of other PBAs for resistive switching in combination with the control of film morphology, stoichiometry, chemical composition, and crystalline structure are rarely investigated.

In this work, the relationship between the structural properties and resistive switching behavior of electrodeposited cobalt–iron PBA films is highlighted. The morphological and structural characterizations are performed with electron microscopy in combination with Raman spectroscopy and different X-ray techniques. Moreover, resistive switching behavior is detected in the PBA films. The electrical switching characteristics are carefully analyzed and discussed.

[1] L. B. Avila et al., Materials 12 (2020) 5618.

[2] F. L. Faita et al., J. Alloys Compd. 896 (2021) 162971.

[3] M. Pohlitz et al., Materials 15 (2022) 7491.

The purpose of this study was to determine the quantitative and qualitative effects of the synthesized three lignin derivatives on the decomposition of PLA under different measurement conditions. The first step to achieve this goal was to understand the thermal and flammability properties of polylactide composites containing dibutyl-lignosulfonamide (DBA), N-butyl-N-dodecyl-lignosulfonamide (NNA), and didodecyl-lignosulfonamide (DDA). For this purpose, TGA, DSC, and MCC analyses were performed, not only on the individual raw materials, but also on PLA/DBA, PLA/NNA, and PLA/DDA composites with 3, 6, and 9 wt% filler content. The results of these analyses showed that lignosulfonamides can be an effective bioantipyrine, as they allow a 20-30% reduction in flammability compared to PLA.

Conductive organogels derived from natural biopolymers offer significant potential for wearable and stretchable sensing devices due to their renewable, non-toxic, biocompatible, and biodegradable properties, as well as their outstanding flexibility and conductivity. Currently, the integration of smart properties such as good mechanical properties, self-healing capability, and high strain sensitivity for fabricating hydrogel-based strain sensors remains challenging. Herein, we developed guar gum/gluten-based organogels crosslinked via dynamic covalent bonds. The effect of three additives, such as tannic acid (T), glycerol (G), and sodium chloride (NaCl) on organogel properties was studied. The addition of TA remarkably enhanced tensile strength, self-adhesive capabilities, and conductivity. Additionally, the incorporation of NaCl within the range of 0-5 wt% improved self-adhesion ability. Moreover, the presence of glycerol in the strain sensors decreased self-healing time. The optimal composition of three additives was found at 3.75 wt% T, 30 vol% G, and 5 wt% NaCl. This composition exhibited a gauge factor (GF) of 0.6% at a stretchability of 665%. After storing the organogel for 7 days, the sample demonstrated long-term stability in self-healing, with an efficiency of 98%.