română ECATERINA ANDRONESCU, MIRCEA BEURAN, DAN CORNELIU JINGA, CLAUDIU STEFAN TURCULET
Abstract
Technological evolution and the complexity of approaches force researchers and practitioners to take interdisciplinary approaches. Nanoscience has opened up the field of 1-100 nm dimensions in materials science, where properties change significantly, forcing researchers to reconsider applications and highlighting new opportunities. The synthesis and characterization of nanoparticles have led to the opening of a new field of applications – nanomedicine. The choice of medical therapies appropriate to the medical information obtained directly from the patient – personalized medicine as well as the association of diagnosis with the treatment itself – the teranostic approach evolves in integration with artificial intelligence. The article marks the opening of a challenging topic that energizes the evolution and precision of medical procedures.
Keywords
nanoparticles, nanomedicine, teranostic approach, artificial intelligence
MIHAI EFTIMIE, CARMEN UDREA, ALINA MELINESCU, ANA FILIP
Abstract
Borosilicate glass samples were prepared by doping a main composition with CoO and NiO, respectively, to study the influence of these ions on the optical, structural, thermal, and chemical properties. Two compositions were prepared from analytically pure reagents, melted in alumina crucibles at 1250°C, cast into graphite molds, and annealed to remove internal stresses. The glasses were characterized using hydrolytic stability tests, dilatometry, UV-Vis spectroscopy, viscosity measurements, and FTIR spectroscopy. The results show that both Co2+ and Ni2+ change the vitreous network and optical behavior even at low concentrations (0.5 wt.%). The Ni2+-containing glass exhibits better hydrolytic stability and a lower coefficient of thermal expansion, while the Co2+-containing glass has a shorter working range due to a more rapid variation of viscosity with temperature. The UV-Vis spectra confirm the characteristic absorption bands of Co2+ and Ni2+ ions, indicating tetrahedral coordination for Co2+ and a combination of tetrahedral and distorted octahedral coordination for Ni2+. FTIR analysis indicates structural rearrangements of the Si-O-(NBO) and [BO3]3-/[BO4]5- units induced by the dopants. The study demonstrates that the addition of CoO and NiO allows for the modulation of the processing behavior of borosilicate glasses, a relevant aspect for functional applications.
Keywords
borosilicate glass, cobalt oxide, nickel oxide, colored glass, optical properties, FTIR spectroscopy
SUDARSONO, PRINOB AKSAR, ABDUL KHOIRI AL-LATIF, MUHAMMAD RIFKY
Abstract
Geopolymer concrete is an innovative environmentally friendlier material in terms of being a replacement material for Portland cement by using silicate and aluminium materials like fly ash to replace both natural stone and powder aggregates. In this study, we investigate the effect of adding fiberglass fibers to the physical and mechanical properties of fly ash-based geopolymer with porous structures. In terms of geopolymers we use alkali activators (sodium hydroxide NaOH and sodium silicate Na2SiO3) and foaming agent to prepare lightweight concrete. Fly ash is combined with fiberglass fibers in the weight percentages of 0.00, 0.25 and 0.50 The tests, include density, porosity and compressive strength along with microstructural analysis using Scanning Electron Microscope (SEM). The findings indicated an increase in the porosity value from 32.83% to (44.90%) with decreasing density value from 1.1953 to 1.0042 g/cm3 ranging of fiber content addition respectively On the other hand, while porosity was increased its value in compressive strength significantly increased from 3.41 MPa up to 9.29 MPa. Results of microstructural analyzes showed that in the case of the sample devoid of fibers, a loose pore structure was observed, consisting of unevenly distributed and partially unstable pores while addition of fibers led to a more uniform pore system. A more connected pore network was obtained at higher fiber content. The improved mechanical performance was attributed to the reinforcing effect of the additions of fiberglass fibers that increased pore stability, permitted efficient stress distribution and acted as crack intermediary mechanism in the geopolymer matrix. A balance point between mechanical strength and lightweight was reached at 0.25 fiber percentage. This evidence demonstrates that applying fiberglass reinforcement develops high-performance lightweight geopolymer composite materials suitable for structural applications.
Keywords
fly ash, foamed geopolymer, fiberglass fiber, compressive strength, porosity, microstructure
LONGHAI YE
Abstract
Tensile behavior of Two-dimensional carbon fiber reinforced silicon carbide composite （2D-C/SiC） composites was also studied systematically under quasi-static and high strain rate conditions at temperatures of 20, -70, -150 ℃ to the liquid nitrogen temperature ( -196 ℃). Mechanical loading was performed on a universal testing system with low strain rates and a split Hopkinson tensile bar system with dynamic regimes, with strain rates between 10−3 and 300 s−1. In all test conditions, the material showed a clear nonlinear stress-strain behavior before failure, which is indicative of its pseudo-plastic deformation behavior. Cooling and loading rate were both found to enhance strength. Tensile resistance was observed to rise significantly as the environment changed to cryogenic temperatures. An analogous strengthening behavior was noted as strain rate increased, which is rate-dependent mechanical behavior. Fractographic analysis also helped to understand the mechanisms of damage. In the quasi-static loading, strong fiber pull-out characteristics were observed, indicating progressive interfacial debonding before ultimate failure. Conversely, specimens with dynamic loading exhibited significantly shorter pull-out lengths, suggesting a higher interfacial constraint and more sudden fracture mechanisms. At low temperatures, fracture surfaces appeared irregular and rugged. Instead of massive bundle extraction, localized fiber cluster pull-out with comparatively smooth fracture traces on the extracted clusters dominated failure.
Keywords
2D-C/SiC, composite material, low temperature, dynamic tensile
XIAOFENG CHEN, QIAN HONG, LIHUA DING, YANBING WANG, XIAOXIAO MA, XIAOHU SUN, JINGJING ZHOU, JIA HU, XIN LUO
Abstract
The traditional ordinary Portland cement has a relatively high pH value, which is often extremely unfavorable for vegetation restoration when slope protection treatment is carried out. For this purpose, in this study, ammonium dihydrogen phosphate (ADP) is selected to excite steel slag (SS) to generate cementitious materials with a lower pH value, which are used to bond recycled aggregates, and a porous ecological concrete with a low pH value and environmental friendliness is prepared. The results show that when the SS/ADP is 6 and the water-cement ratio is 0.22, the compressive strength of the prepared cementitious material reaches 37.7 MPa. When it is compounded with aggregates with particle sizes ranging from 12 to 18mm and the slurry-bone ratio is 1/5, the porosity of the prepared porous ecological concrete reaches 35.4%, and the compressive strength reaches a maximum of 4.3 MPa. In addition, it has been confirmed that ADP can significantly reduce the harmful metal ions retained in steel slag, making the content of harmful metal ions in ecological concrete more obviously lower than the national standard limit.
Keywords
acid activation, recycled aggregate, ecological concrete, mechanical properties, mechanism research
WENWEN QI
Abstract
Flexible conductive polymer films require stable charge transport under large deformation, repeated motion, and sweat-related interfacial disturbance. This study develops a polythiophene-based conjugated polymer/multi-walled carbon nanotube composite film using gradient drop-casting, zeta-potential-guided dispersion control, and electric-field-assisted network biasing. The strategy aims to separate a mechanically compliant domain from a current-carrying backbone, thereby reducing conductive-network fracture and signal drift during dynamic strain. The optimized film shows a carbon nanotube orientation degree of 0.82, crystallinity of 46.5%, surface roughness of 18.7 nm, and filler-distribution deviation of 3.1%. Conductive-cluster connectivity remains above 0.85 within the 0–80% strain range, while impedance drift is only 1.2% after 2 × 105 loading cycles. Under simulated sweat with conductivity of 9.7 mS cm-1, conductivity drift is limited to 0.8%. These results indicate that the proposed network-locking strategy improves electromechanical stability and provides a reliable material platform for human-machine interaction and sports health monitoring
Keywords
flexible conductive polymer films, dynamic percolation network, multi-walled carbon nanotubes, solvent-induced self-assembly, electric-field biasing, strain sensing, human-machine interaction
MOHAMED BACHAR, DJILLALI CHACHI, REBIH ZAITRI
Abstract
In this study, we have examined the influence of straight-strand fibre reinforcement on the post-cracking mechanical behaviour of natural aggregate concrete (NAC) and recycled aggregate concrete in which 50 % of the natural coarse aggregate has been replaced by recycled aggregate (RAC50). The parameters studied experimentally have included compressive strength, compressive toughness and dynamic impact energy.The results revealed a significant increase in energy dissipation compared with the reference concrete (0 % fibres), throughout the range of fibre volume fractions (0 %–2 %) and aspect ratios (h/d=60, 80,100). A more significant rate of change in both modes of energy dissipation was observed for fibre-reinforced concrete with recycled aggregates (RAC50-SF) than for fibre-reinforced concrete with natural aggregates (NAC-SF). At a dosage of 1.5 % and an aspect ratio of (h/d=100), both types of concrete, (RAC50-SF) and (NAC-SF), exhibit similar values for both energy modes, thus making recycled concrete suitable for use in high-performance structures.
Keywords
compressive strength, recycled aggregate concrete, compressive toughness, dynamic impact energy, fiber-reinforced concrete
LEILA BAZIZ, NADJET BENCHIHEUB, ABDELAZIZ SID, ISMAHANE SERRADJ
Abstract
This investigation is devoted to study the particular impact of laser Nd:yag radiation on certain mechanical properties such that: elastic modulus, hardness and stiffness of two types of Al-Si-Cu-Mg alloys (industial and recycled) through nanoindentation measures. These materials were subjected to a Laser treatment Nd: Yag with wavelength λ=1.064nm, for different pulse counts. The Atomic Force Microscope (AFM) is used to visualize and analyze radiated regions at the nanoscale, as well as to conduct nanoindentation tests for assessing hardness, stiffness and elastic modulus. In this context, the present study demonstrates that both elasticity and hardness of the radiated areas increase with the number of laser shots. Following a specific number of shots (40 shots for industrial aluminum and 60 shots for the recycled one); all radiated zones display analogous nanoindentation profile. Due to the changes induced to a nanostructural refinement shown by the (SEM); further a significant improvement in mechanical properties is achieved .However, increasing the number of shots to high levels (about 160 shots for industrial aluminum and 200 shots for recycled aluminum) cause a homogenate material structure, resulting an improvement in mechanic properties.
Keywords
recycled aluminum alloys, industrial aluminum alloy, Nd:Yag laser, nanoindentation, elasticity and hardness
OANA CAMELIA IACOB
Abstract
This paper presents an analysis of economic sustainability models for the states that are part of the European Union (EU). The analysis is a data-mining type and is carried out for the data related to the year 2024. The main objective of the research is to investigate the correlation between the circular economy indicators, the environmental taxation method and the industrial performance of each country. The research consists of two approaches that complement each other. The first direction uses an unsupervised learning algorithm to form clusters based on the European economies. This is done according to their countries ability to integrate and reuse circular materials in industry. Also, within this direction, environmental taxes and trade flows of recyclable raw materials that characterize the clusters with the highest degree of resource efficiency are identified. The second direction uses a supervised classification algorithm to identify critical economic thresholds (pollution taxes, energy taxes and foreign direct investment flows). These economic thresholds can be said to determine the degree of success of a country in achieving a high rate of circular use of materials in production. The attribute related to this rate is transformed into nominal classes and based on it, decision rules are extracted. The attributes used in the analysis are intended to cover aspects related to waste management, import dependence and foreign direct investment. The present research provides a picture of how environmental fiscal policies and material flows influence the transition within the EU towards a circular economy.
Keywords
sustainability, environmental taxation, circular economy, data mining analysis.