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Coarse to Fine: The Role of Severe Plastic Deformation in Advancing Titanium-Based Medical Implants - A Comprehensive Review
No full textThis paper describes severe plastic deformation (SPD) procedures, which are utilized to form an ultrafine-grained structure in metallic biomaterials. During the SPD process, a solid material sample is subjected to very high loads without a significant change in sample dimensions. In the present work, the high-pressure torsion (HPT) process, as one of the SPD techniques, which achieves a high degree of deformation and ensures refinement of the microstructure, will be discussed in more detail. Considering that grain size control is accepted as a method to obtain materials with desired characteristics, an overview of the properties of ultrafine-grained titanium-based biomaterials to be used in medicine is given. Moreover, particular attention is dedicated to the influences of HPT process parameters, primarily hydrostatic pressure, and number of revolutions during torsion, on the grain size and physical and mechanical characteristics (modulus of elasticity, microhardness, and tensile properties), corrosion resistance, and biocompatibility of the titanium-based biomaterials. A review of the literature indicates that titanium-based materials obtained by the SPD process show improved mechanical and physical properties without losing biocompatibility and corrosion resistance, which suggests that these methods of obtaining implants are something that should be further developed in the future
Setting Time of Alkali-Activated Binders Exposed to Co-60 Gamma Radiation
No full textAn investigation of the effect of gamma radiation was carried out on the setting time of alkali-activated binder paste. Mechanically activated coal fly ash (FA), ground granulated blast furnace slag (BFS), and their 1:1 mass mixture (MIX) were activated by water glass with a module of 1.5. Fresh paste was cast into molds and exposed to Co-60 gamma radiation, at a dose rate of 9.62–9.53 Gy/h, until the final setting. The initial and final setting times were determined by measuring the penetration of the Vicat needle at regular intervals. The initial setting times were 1 h 3 min for BFS, 1 h 55 min for MIX, and 3 h 28 min for FA. The final setting times were 1 h 10 min for BFS, 2 h 13 min for MIX, and 4 h 1 min for FA. The received doses were 8.02 Gy for BFS, 17.54 Gy for MIX, and 34.14 Gy for FA. Exposure to gamma radiation resulted in a shorter initial setting time for BFS, a shorter final setting time for FA, and results with an insufficiently visible impact on MIX. For dose rates in the 9–10 Gy/h range, the irradiation by Co-60 gamma rays during setting did not lead to flash, nor did it delay the setting of alkali-activated binder pastes
Dispersive Liquid–Liquid Chelate Microextraction of Rare Earth Elements: Optimization and Greenness Evaluation
No full textAn ultrasound-assisted dispersive liquid–liquid microextraction (DLLME) method was developed to concentrate and quantify rare earth elements (REEs) (Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in acidic aqueous solutions. Tetrachloroethylene (PCE) was used as the diluent, di-(2-ethyl hexyl) phosphoric acid (D2EHPA) as the extracting agent, and acetone as the dispersant solvent. The method was optimized at pH = 2.3, T = 25 °C, and VS = 400 µL of a PCE ÷ D2EHPA mixture (10 ÷ 1) using the response surface methodology (RSM) with a Box–Behnken design. Under optimal conditions, the method proved efficient for the DLLME of most REEs (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), where the achieved recoveries were in the range of 61–109%, while relative standard deviations were in the range 11–28%. The proposed method was applied to recover REEs from real coal ash leachate samples. A greenness evaluation using the Green Analytical Procedure Index (GAPI), Analytical GREEnness (AGREE), and Analytical Eco-Scale (AES) methodologies revealed acceptable metric scores of 74, 0.61, and 26.6–79.8, respectively
Tunnel structured Na0.54MnO2 nanorods synthesized at high-temperature: Cathode material for aqueous Na-ion batteries
No full textThe Na0.54MnO2 powder is synthesized by the glycine nitrate method followed by annealing at 950 °C. Its crystal structure resembles a 3d tunnel with rod-like shapes, with an average crystallite width of 130 nm and a length in the micron range. The electrochemical performance of the Na0.54MnO2 - based electrode is tested in a NaNO3 solution. During potential cycling, the Na+ ions intercalation/deintercalation processes remain reversible, indicating good stability. For the current densities of 1000, 2000, and 5000 mA g−1, the calculated specific capacities are 72.6, 66.8, and 57.5 mAh g−1, respectively. Due to its suitable morphology for easy Na+ ions intercalation/deintercalation and good electrochemical performance, Na0.54MnO2 is a promising cathode material for aqueous Na-ion batteries
Nanostructured pumpkin leaf proteins: fabrication and assembly for hydroxocobalamin encapsulation
No full textThis research provides constructive information on the correlation
between the nanoparticulation process and the properties of protein-based
nanoparticles, achieving a precise control of particle size, uniformity, surface
charge, and hydroxocobalamin encapsulation possibilities. RuBisCO-rich protein
fraction was isolated from pumpkin leaves and was proved to serve as a matrix
for the gelation-, pH-, and desolvation-driven assembled nanoparticles.
Hydroxocobalamin, as a model of nutrient, was encapsulated successfully into
the nanoparticles derived via cold gelation (54%) and antisolvent precipitation
(52%) processes, which have the greatest potential for the fabrication of stable
nanoparticle structures (127 and 282 nm, -16.3 and -18.4 mV, respectively)
Application of Pipe Ring Notched Tensile (PRNT) Specimens to Fracture Mechanics Testing of Ductile Metallic Materials
No full textThis paper presents the results of experimental and numerical analysis of fracture mechanics testing of ductile metallic materials using a non-standard procedure with PRNT (pipe ring notched tensile) ring-shaped specimens, introduced in previous publications through analysis of 3D-printed polymer rings. The main focus of this research is the determination of the values of the plastic geometry factor ηpl since the specimen is not a standard one. Toward this aim, the finite element software package Simulia Abaqus was applied to evaluate the J-integral (by using the domain integral method) and the F-CMOD curve so that the plastic geometry factor ηpl can be evaluated for different values of the ratio of crack length to specimen width (a0/W = 0.45 ÷ 0.55). In this way, a procedure and the possibility of practical implementation on the thin-walled pipelines are established
Review and Perspectives on the Sustainability of Organic Aerogels
No full textAerogels are exceptionally lightweight materials characterized by their high open porosity and remarkable specific surface area, currently used across a wide array of industrial sectors from construction to energy storage and have great potential for expanding their applicability and unlocking new market opportunities. Driven by global economic growth and an intensifying environmental crisis, there is a growing demand for engineering innovations that prioritize sustainability. Aerogels are well-positioned to support these sustainability efforts. Their unique properties make them ideal for energy-saving solutions, environmental remediation, and more efficient use of resources. As the demand for eco-conscious technologies rises, aerogels are poised to contribute significantly to the development of greener, more efficient products and processes across multiple industries. The sustainability of aerogel technology is crucial for the mid-to-long-term future, yet its current status has been scarcely reviewed in the literature. This Perspective explores and critically reviews significant advances on organic and hybrid aerogels in the current socioeconomic scenario, with selected case studies endorsing their contribution to the UN Sustainable Development Goals. It also identifies research gaps while proposing innovative strategies to enhance the sustainability of aerogel production through the application of circular economy principles. Key strategies discussed involve the fabrication of aerogels using eco-friendly sources, such as biopolymers derived from biorefinery processes or from waste materials. Additionally, this Perspective examines the development of methods for the reuse, recycling, and end-of-life management of aerogels, along with the implementation of more efficient processing routes. Ultimately, this work highlights the need for comprehensive assessments of aerogel sustainability through life cycle assessment (LCA) and evaluations of safety and toxicity. By addressing these critical aspects, the potential of aerogels to contribute to a more sustainable future appears highly favorable from both commercial and research perspectives, paving the way for a circular aerogel economy and providing a lasting impact to the society in which we live
Еко-репелент
No full textЕКО-репелент представља најновије достигнуће у борби против инсеката штеточина у складиштима семена и зрна махунарки и житарица. Произведен је еколошки прихватљивом технологијом.Посебно признање „Kорак у будућност
Effects of silver coated graphite particles on mechanical and electromagnetic shielding properties of an epoxy resin
No full textThe metallization of graphite particles by the deposition of silver particles onto their surfaces was studied. By
using a silver conductive dispersion obtained via a modified Tollens process, elemental silver was deposited to
the surfaces of the graphite particles. Graphite particles were treated with three different volumes of the silver
conductive dispersion. Various analyses were conducted to examine the properties of the particles, including
FESEM/EDS, XPS, XRF, and XRD analyses. After characterization, modified graphite particles are used to produce composites based on epoxy resins. Additionally, the polymer characteristics were evaluated through the
viscosity determination and torsion dynamic mechanical thermal analysis. The study also explored the relationship between the mechanical properties of the composite and the mass fraction of modified graphite particles, along with the electromagnetic interference shielding efficiency in the X-band. Analysis of the powder
particles showed a significant concentration of elemental silver on the particles’ surface. The incorporation of
these graphite particles enhanced the physical and mechanical properties of the composite. The average attenuation of the wave intensity increases by 21 % with the deposition of silver compared to the graphite sample
without silver. The average attenuation of wave intensity for samples with mass ratios of 10, 20, 30, and 40 wt %
were recorded at 3.68, 6.04, 7.06, and 8.01 dB, respectively
Probiotics as a Novel Therapeutic Strategy for Infection Control in Normo- and Hyperglycaemic Conditions
No full textIntroduction: Diabetic foot ulcers (DFUs) represent one of the most severe
complications of diabetes mellitus, a chronic metabolic disorder
characterized by persistent hyperglycemia. Local hyperglycemia within
DFUs creates an environment conducive to pathogenic microbial
colonization and infection, significantly impairing wound healing and often
resulting in lower limb amputation. One of the major challenges in DFU
management is the simultaneous control of infection and underlying
metabolic dysregulation. Conventional treatments, including systemic
antibiotics and topical antimicrobials, are increasingly limited by the
emergence of multidrug-resistant (MDR) pathogens [1]. Consequently, there
is a pressing need for innovative, multi-targeted therapeutic strategies. In this
context, probiotics have emerged as promising candidates due to their
potential antimicrobial, anti-inflammatory, and immunomodulatory
properties [2, 3]..