Aging Tests Research Articles

Decision Tree-Based Classification Approach to Discover Factors Affecting Vitamin D Level with Machine Learning

Purpose: Vitamin D level is emphasized as an important biomarker in determining risk factors for different diseases. Vitamin D is an important vitamin for human health and its deficiency is associated with serious health problems. Therefore, it is of great importance to detect vitamin D deficiency, which can be easily prevented and treated. The possible relationship between vitamin D deficiency and musculoskeletal pain, osteoporosis, diabetes mellitus, hypertension is frequently discussed in researches. In this research, it is aimed to analyze the factors in determining the vitamin D level and the decision rules related to it. Methods: A descriptive framework based on one of the machine learning techniques, that is decision tree is followed. The data used to create the decision rules were obtained from volunteers between the ages of 18-85 who applied to Izmir Katip Çelebi University Atatürk Training and Research Hospital Infectious Diseases and Family Medicine Polyclinics and agreed to participate in the study between 01.03.2017 and 01.09.2017. Results: It was observed that age, gender and laboratory test values are strong predictors for vitamin D level. As a result of two CART (Classification and Regression Trees) models, %90.47 and %95 predictive accuracies were observed respectively. In the first model, uric acid, age and creatine; in the second model TSH, ALP and smoking(yes) were the most important three biomarkers affecting vitamin D level. Discussion: The collected features give a comprehensive list of variables that have an effect on vitamin D in the dataset under consideration. Important findings of the study include not only the identification of these variables, but also the effective categorization determination procedures. In contrast to previous research, the Age variable is the most influential factor within the scope of this dataset, which includes demographic information on patients and their existing disorders.

Ancient architectural pathology of blue bricks and brick carvings in Northwest China: Example from the White Temple Tower

Rising damp is one of the main problems affecting historical masonry structures worldwide, as it affects the appearance of heritage architecture and reduces strength. In this study, to reproduce the pathologies as much as possible and explain the mechanism, the aging test was set up with the climate data (temperature, humidity, etc.) derived from the real environment in nature at the location of the White Temple Tower, which was the object of this study. The tests mimicked the temperature, humidity, and types of salt solutions as closely as possible. Unlike the traditional aging test (producing specimens in accordance with some standards), two samples of blue brick carvings and blue brick cubes were used for the test. The results show that brick carvings suffered more severe surface degradation than brick cubes under various circumstances. Brick specimens' mechanical characteristics, such as wave velocity and compressive strength, were greatly diminished, and there was a fluctuating trend in surface hardness and color difference. The data indicate a size effect on the weathering between brick carvings and brick cubes, with the former displaying a faster rate of weathering under identical conditions. The experiment successfully simulates some of the phenomena observed in the field and provides an idea for studying the weathering of brick artifacts.

Capacitive and Efficient Near-Infrared Stimulation of Neurons via an Ultrathin AgBiS2 Nanocrystal Layer.

Colloidal nanocrystals (NCs) exhibit significant potential for photovoltaic bioelectronic interfaces because of their solution processability, tunable energy levels, and inorganic nature, lending them chemical stability. Silver bismuth sulfide (AgBiS2) NCs, free from toxic heavy-metal elements (e.g., Cd, Hg, and Pb), particularly offer an exceptional absorption coefficient exceeding 105 cm-1 in the near-infrared (NIR), surpassing many of their inorganic counterparts. Here, we integrated an ultrathin (24 nm) AgBiS2 NC layer into a water-stable photovoltaic bioelectronic device architecture that showed a high capacitive photocurrent of 2.3 mA·cm-2 in artificial cerebrospinal fluid (aCSF) and ionic charges over 10 μC·cm-2 at a low NIR intensity of 0.5 mW·mm-2. The device without encapsulation showed a halftime of 12.5 years under passive accelerated aging test and did not show any toxicity on neurons. Furthermore, patch-clamp electrophysiology on primary hippocampal neurons under whole-cell configuration revealed that the device elicited neuron firing at intensity levels more than an order of magnitude below the established ocular safety limits. These findings point to the potential of AgBiS2 NCs for photovoltaic retinal prostheses.

Low-temperature strain-free encapsulation for perovskite solar cells and modules passing multifaceted accelerated ageing tests

Perovskite solar cells promise to be part of the future portfolio of photovoltaic technologies, but their instability is slow down their commercialization. Major stability assessments have been recently achieved but reliable accelerated ageing tests on beyond small-area cells are still poor. Here, we report an industrial encapsulation process based on the lamination of highly viscoelastic semi-solid/highly viscous liquid adhesive atop the perovskite solar cells and modules. Our encapsulant reduces the thermomechanical stresses at the encapsulant/rear electrode interface. The addition of thermally conductive two-dimensional hexagonal boron nitride into the polymeric matrix improves the barrier and thermal management properties of the encapsulant. Without any edge sealant, encapsulated devices withstood multifaceted accelerated ageing tests, retaining >80% of their initial efficiency. Our encapsulation is applicable to the most established cell configurations (direct/inverted, mesoscopic/planar), even with temperature-sensitive materials, and extended to semi-transparent cells for building-integrated photovoltaics and Internet of Things systems.

Biomass valorization toward sustainable bio-oil obtained by pyrolysis of lignocellulosic raw materials for bitumen modification

The quality and durability of road surfaces have long been an area of interest for researchers all over the world, who are trying to prolong life of service of roads and cut the additional expenses. The quality of bitumen, one of the most important parts of road building materials, can be improved with various modifiers, lots of which have been introduced and used commercially for a long time. This paper studies bio-oil obtained in the process of slow pyrolysis of sawdust as a sustainable modifier for bitumen production. Adhesive properties of bitumen produced by different methods of bio-oil introduction into the material are studied, as well as some of the no-harm characteristics. It was found that introducing both bio-oil and its fraction boiling above 350 °С directly into bitumen leads to a rise in adhesion rate (up to 91.52 % for unfractionated bio-oil and 79.98 % for bio-oil >350 °С fraction vs. 62.88 % for base bitumen). However, adding >350 °С fraction of bio-oil proved to deteriorate the bitumen’s rheological characteristics, such as ductility and penetration, while adding bio-oil made bitumen fail the ageing test (mass change). The addition of bio-oil in the amount of 1 wt% into vacuum, residue showed to have a limited effect on the adhesion properties of the resulting oxidized bitumen, while passing both no-harm and ageing tests. The results reported that the optimal concentration of bio-oil added to bitumen in the case of the current study was 2–3 wt%, since it is at this share of the modifier that the binder shows peak adhesion indicators of the adhesion with the mineral surface.

A Colloidal-Quantum-Dot Integrated U-Shape Micro-Light-Emitting-Diode and Its Photonic Characteristics.

A special micro LED whose light emitting area is laid out in a U-like shape is fabricated and integrated with colloidal quantum dots (CQDs). An inkjet-type machine directly dispenses the CQD layer to the central courtyard-like area of this U-shape micro LED. The blue photons emitted by the U-shape mesa with InGaN/GaN quantum wells can excite the CQDs at the central courtyard area and be converted into green or red ones. The U-shape micro LEDs are coated with Al2O3 by an atomic layer deposition system and exhibit moderate external quantum efficiency (6.51% max.) and high surface recombination because of their long peripheries. Low-temperature measurement also confirms the recovery of the external quantum efficiency due to lower non-radiative recombination from the exposed surfaces. The color conversion efficiency brought by the CQD layer can be as high as 33.90%. A further continuous CQD aging test, which was evaluated by the strength of the CQD emission, under current densities of 100 A/cm2 and 200 A/cm2 injected into the micro LED, showed a lifetime extension of the unprotected CQD emission up to 1321 min in the U-shape device compared to a 39 min lifetime in the traditional case, where the same CQD layer was placed on the top surface of a squared LED.

The Effects of Aging on Microstructures and Rheological Properties of Modified Asphalt with GO/SBS Composite.

This work aimed to investigate the effects of aging on the microstructures and rheological properties of modified asphalt with a GO/SBS composite, since the styrene-butadiene-styrene block copolymer is potentially compatible with graphene oxide (GO). The GO/SBS composites, which were used as a kind of modifier, were prepared via the solution-blending method. GO/SBS composites with varying GO contents were employed to prepare the GO/SBS-compound-modified asphalt (GO/SBS-MA). Then, the GO/SBS-MA underwent PAV (pressure aging vessel) or UV (ultraviolet) aging tests to simulate different aging circumstances. The microstructures of the asphalt binders were studied using FTIR (Fourier-transform infrared spectroscopy) and AFM (atomic force microscope) tests. Moreover, DSR (dynamic shear rheometer) and BBR (bending beam rheometer) experiments were carried out to investigate the rheological properties of the GO/SBS-MA. The results showed that the addition of GO improved the high-temperature stability of the asphalt binder while slightly impairing its performance at low temperatures. GO restrained the formation of carbonyl and sulfoxide groups as well as the breakdown of C=C bonds in the polybutadiene (PB) segment, promoting the anti-aging performance of GO/SBS-MA. Furthermore, the interactions between the GO/SBS and the asphalt binder resulted in the formation of needle-like aggregates, enhancing the stability of the asphalt binder. The asphalt binders with a higher content of graphene oxide (GO) exhibited not only a better high-temperature performance, but also a better aging resistance. It was concluded that the macroscopic properties and microstructures were significantly affected by GO, and a moderate increase in the amount of GO could contribute to a better aging resistance for GO/SBS-MA.

A novel inorganic phosphate-based adhesive for bonding archaeological pottery: a preliminary exploration

Damage and fracture of archaeological potteries not only jeopardize the long-term preservation but also hinder their exhibition. To repair these pottery sherds effectively, this study introduces a novel inorganic phosphate-based adhesive and evaluates its effectiveness through a series of experiments. To determine the optimal base adhesive, the paper investigates the influence of varying weight ratios of the H2O–H3PO4 system and the Al(OH)3–H3PO4 system on properties including tensile lap-shear strength, microstructure, high-temperature resistance and phase composition. However, the original black color of the traditional CuO–phosphate adhesive limits its application. The innovation of this study lies in the addition of nano-TiO2 to the adhesive, which not only improves the bonding strength but also adjusts the color of the adhesive. This study has defined the optimal formulation (i.e., base adhesive = m[Al(OH)3]:m[H3PO4] = 7:100, filler = 10wt% nano-TiO2), and the final product shows no residual acid in adhesives. Additionally, the fracture surfaces are successfully bonded with a high strength of 3.56 MPa. Various ageing tests including dry-thermal ageing, hygrothermal ageing and UV irradiation ageing are conducted to assess the ageing resistance of the inorganic phosphate-based adhesive. The results indicate strong tolerance of adhesive to high temperature and high humidity environment. Preliminary applications in archaeological pottery restoration suggest that the inorganic phosphate-based adhesive offers considerable promise for repairing shattered pottery.Graphical

Time-varying compressive properties and constitutive model of EPDM rubber materials for tunnel gasketed joint

The stress relaxation of ethylene propylene diene monomer (EPDM) rubber material in a compressed state significantly increases the risk of water leakage at tunnel precast segmental joints. Additionally, EPDM rubber gaskets typically experience a complex precompression strain state, further complicating the prediction of long-term stress relaxation. Therefore, it is imperative to propose a novel constitutive model that realistically reflects the stress relaxation of rubber with arbitrary precompression strain, providing a reference for the long-term waterproof design of shield tunnels. In this study, the time-varying properties of EPDM rubber at material level were studied in detail. At first, a comprehensive set of accelerated aging tests were conducted on EPDM rubber samples with varying precompression strains. The hardening effect of rubber without precompression and the stress relaxation effect of rubber with precompression were explored. The time-varying law and mechanism governing rubber properties under these two effects were analyzed. Subsequently, a conversion relationship between the EPDM rubber test conditions and the actual service time was established. The predicted hardening coefficient for uncompressed EPDM after 100 years is 1.468, whereas the relaxation coefficient for compressed EPDM is 0.359. Comparative analysis revealed that the compression set index do not consider the beneficial effects of hardening, resulting in a 54.1% overestimation of the design water pressure. Finally, the analytical study on the constitutive model of EPDM rubber material was carried out. The error in compression curve for unaged sample obtained from empirical formulas exceeded three times that of the analytical model, underscoring the need to study time-varying constitutive models. An interpolation method was employed to extend the test curve, leading to the development of a new constitutive model that represents the stress relaxation characteristics of EPDM materials under arbitrary precompression strain states. By combining the proposed constitutive model with the timetemperature conversion relationship, the time-varying expressions of the constitutive parameters for relaxation and hardening effects during the service life were derived. In comparison with existing models, the proposed model demonstrates wider applicability, effectively captures the time-varying characteristics of EPDM materials under arbitrary precompression strains, offering an efficient approach for studying the long-term stress relaxation prediction of rubber gaskets in shield tunnels under complex precompression strain states.

Physiological and Molecular Analysis of Soybean Seed Longevity and Validation of Candidate Markers

Background: Seed longevity is a major constraint in soybean seed production. The major focus of this study is to analyze the physiological and molecular changes associated with seed longevity and identify promising germplasm which are good storers for soybean breeding program. Methods: Nineteen genotypes were studied for seed longevity using accelerated ageing test and genetic integrity based on SSR marker data. Genotypes were clustered into distinct groups based on seed morphological and physiological parameters (Mahalanobis D2 analysis). SSR markers for seed longevity were validated in the germplasm. Result: Per cent reduction in germination after accelerated ageing was significantly and positively correlated with traits associated with seed storability such as seed length, seed width, seed thickness and 100 seed weight and negatively correlated with seedling vigour indices. Hence, it would be worthwhile to rely upon these parameters for enhancing the seed storability in soybean. Genetic integrity of the germplasm was evaluated based on SSR markers in accelerated ageing seeds. SSR markers (Satt 285, Satt 534, Satt 538, Satt 281, Satt 162, Satt 631 and Satt 371) revealed significant association for the seed longevity characters such as seed length, seed width, seed thickness and seed weight. Candidate markers (Satt 371, Satt 281, Satt162, Satt 285, Satt 534) which can differentiate the soybean genotypes for storability have been identified in this study. The genotypes were grouped into seven clusters with monogenotypic cluster III (PSPB23) having minimum reduction in germination after accelerated ageing.

Is Chinese Medicine Facing a Potential Workforce Crisis in Australia? Demographic Changes in the Profession over the Last Decade.

Background: As a prominent part of complementary and alternative medicine, Chinese Medicine (CM) has proved its strengths in treating a diverse range of acute and chronic medical conditions and is at present recognized in 196 countries and territories worldwide. In 2012, Australia regulated the CM profession under the National Regulation and Accreditation Scheme (NRAS) by legislation and reports quarterly demographic information about individual CM practitioners so to ensure public interest, although research examining the change of CM workforce in Australia has been scarce. Objective: This study aims to investigate the construction of the CM workforce in Australia and more importantly, evaluated its development in the last decade to capture the trajectory and trend in the present period and future potential changes. Methods: Data were sourced from the Australian Health Practitioner Regulation Agency (AHPRA) annual reports and the Chinese Medicine Board of Australia (CMBA) registration statistics from 2012 to 2023. A descriptive analysis was conducted with demographic variables, including profession, age, and gender, and chi-square tests and linear regression modeling were carried out to assess the variations between regions and across years. Results: The population of CM practitioners in 2022/2023 stagnated with slight decrease to 4,823, in contrast to the increase rate of 2.9% in the whole health care community. The number of young CM registrants (<35 y) shrank by 37.5% from 691 in 2012 to 432 in 2023. In comparison with other health care professions, CM comprises the smallest proportion of the population aged younger than 25 (0.2%) and the largest proportion aged older than 65 years (16.2%), advancing into an aging era. Conclusions: This study indicates a worrying potential decline in CM workforce in Australia, which is likely to be further exacerbated by the lack of new graduates and rise of median age among practitioners. Meanwhile, continued advancement in Western medicine technology and standards requires substantial efforts to increase both a better understanding of CM and demonstration of its efficacy. Furthermore, greater effort is needed to recruit and educate new young CM practitioners in Australia and to broaden the international training pipeline for a sustainable development of CM practice.

Time and Doses of Bacillus Subtilis in Leaf Application of Bean Plants

Common beans P. vulgaris is an important food in the diet of the Brazilian population. Currently the use of microorganisms, such as B. subtillis, has been increasing significantly as an alternative to improve productivity of beans. The objective of this research was to identify the ideal dose of the commercial product (Panta Premium) based on B. subtilis, the best time and doses for leaf application, grain yield and its components and seed quality of bean. The statistical design was randomized blocks arranged in a factorial scheme (3 x 6) with four replicates. Three application times (V3, V4, and R5 stages) and six doses of the inoculant based on B. subtilis - strain UFMT Pant001 (0, 200, 400, 600, 800, and 1000 mL per ha-1) were assessed. The number of pods per plant, number of grains per plant, number of grains per pod, 1000-grain weight, grain yield, seed germination, vigor test, first germination count, and accelerated aging test were evaluated. That the 1000-grain weight was not influenced by the different doses and times of B. subtilis application. Positive linear regression with an increase in the number of pods per plant as the dose of inoculant (mL ha-1) increased when applied at the R5 stage. V3 and V4 stages, there was a linear increase (43,1 e 28,4% respectively) in the number of grains per plant as the dose of B. subtilis increased. At the R5 stage, as seen at the V3 and V4 stages, there is a linear behavior where the number of grains per plant increases as the dose of the inoculant based on B. subtilis increases. the results show that both the dose and the time of application of B. subtilis showed influence on the physiological quality of the seed. The increasing doses of B. subtilis strain UFMT Pant001 increased grain yield compared to the control. The leaf application of Bacillus subtilis strain UFMT Pant001 at stage R5 increased the number of pods and grains per plant and grain yield, regardless of the dose. The leaf application of B. subtilis strain UFMT Pant001 increased the physiological quality of the seeds, attributed to the good fertility of the soil at the site.

The association between remnant cholesterol and bone mineral density in US adults: the National Health and Nutrition Examination Survey (NHANES) 2013-2018.

Previous evidence showed a possible link of dyslipidemia with bone health. Nevertheless, the correlation of remnant cholesterol (RC) with bone mineral density (BMD) has yet to be well investigated. This study investigated the association of RC with total spine BMD in general Americans. This study explored the relationship of RC with total spine BMD in subjects aged ≥ 20 years from the National Health and Nutrition Examination Survey (NHANES) 2013-2018. After adjusting for covariates, multivariate linear regression and stratified analyses were conducted to determine the correlation of serum RC with total spine BMD in adult Americans. Restricted cubic spline (RCS) was applied to examine the nonlinear association of serum RC with total spine BMD. This study included 3815 individuals ≥ 20 years old, 1905 (49.93%) of whom were men and 1910 (50.07%) of whom were women. After adjusting for all covariates, the results showed a negative relationship of serum RC with total spine BMD (β= -0.024, 95% CI: -0.039, -0.010). The interaction tests of age, sex, race, and BMI showed no statistically significant effects on the association. The RCS also indicated a negative linear correlation of serum RC with total spine BMD (nonlinear P = 0.068, overall P < 0.001). Moreover, RC had a stronger effect on total spine BMD than total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). This study found that serum RC was negatively related to total spine BMD in U.S. adults. These findings emphasized the important role of RC in bone health in American adults.

A Feasibility Inquiry to the Sustainable Utilization of Few Invasive Flora

Objectives: The study focuses on utilising invasive flora affecting the indigenous plants and thereby bring about monetary benefits to the local people by means of handmade papers from the invasive weeds. Methods: Handmade paper from five invasive plants namely, Eichhornia crassipes, Eupatorium odorata, Combretum indicum, Lantana camara and Hyptis capitata was attempted. These plants after collection from Nilambur, Kerala were subjected to treatment with washing soda, blending, vat preparation, moulding and drying. This is followed by checking the paper quality parameters viz., Productivity, Clarity/opacity/transparency, Strength, Grammage, Paper grain, Ageing of paper and Moisture content. Findings: Out of the five invasive plants tested, the fibre yield was maximum for Eichhornia, but the productivity rate was less compared to other samples. Lantana and Hyptis yielded maximum productivity even though the fibre yield from these plants was less. The fibre uniformity of paper developed was positively detected for all the 4 plants except Eichhornia thereby proving the feasibility for paper manufacture. All sample paper allows the light; so, all are translucent in nature. Integrity of paper samples was retained in the paint test. The age test also yielded positive results. The gsm test showed lowest for Eichhornia as 98.12g/m2; Lantana 111.87g/m2; Combretum 131.87g/m2; Hyptis 163.75g/m2; Eupatorium is 255g/m2. Even though the gsm of Eichhornia is the best for paper manufacture according to gsm standards, the lack of fibre uniformity is a withdrawing feature for feasibility. The moisture content appeared high for Eichhornia and lowest for Combretum. Novelty: To date, studies on invasive plant utilisation done individually; no comparative study on productivity done. Current study can be further refined for environmental sustenance along with livelihood for local people. Keywords: Invasive Flora, Paper manufacture, Grammage test, Productivity, Ecological sustainability

Do sex, age, and comorbidities modify the association of socioeconomic status and opioid use after total hip arthroplasty?: a population-based study from the Danish Hip Arthroplasty Register.

We aimed to examine the association between socioeconomic status (SES) markers and opioid use after primary total hip arthroplasty (THA) due to osteoarthritis, and whether sex, age, or comorbidities modify any association. Using Danish databases, we included 80,038 patients undergoing primary THA (2001-2018). We calculated prevalences and prevalence ratios (PRs with 95% confidence intervals [CIs]) of immediate post-THA opioid use (≥ 1 prescription within 1 month) and continued opioid use (≥ 1 prescription in 1-12 months) among immediate opioid users. Exposures were individual-based education, cohabitation, and wealth. The prevalence of immediate opioid use was ~45% in preoperative non-users and ~60% in preoperative users (≥ 1 opioid 0-6 months before THA). Among non-users, the prevalences and PRs of continued opioid use were: 28% for low vs. 21% for high education (PR 1.28, CI 1.20-1.37), 27% for living alone vs. 23% for cohabiting (PR 1.09, CI 1.04-1.15), and 30% for low vs. 20% for high wealth (PR 1.43, CI 1.35-1.51). Among users, prevalences were 67% for low vs. 55% for high education (1.22, CI 1.17-1.27), 68% for living alone vs. 60% for cohabiting (PR 1.10, CI 1.07-1.12), and 73% for low wealth vs. 54% for high wealth (PR 1.32, CI 1.28-1.36). Based on testing for interaction, sex, age, and comorbidity did not statistically significant modify the associations. Nevertheless, associations were stronger in younger patients for all SES markers (mainly for non-users). Markers of low SES were associated with a higher prevalence of continued post-THA opioid use. Age modified the magnitude of the associations, but it was not statistically significant.

Phase transition-driven encapsulation of biomolecules using liquid metal with on-demand release for biomedical applications

Robust encapsulation and controllable release of biomolecules have wide biomedical applications ranging from biosensing, drug delivery to information storage. However, conventional biomolecule encapsulation strategies have limitations in complicated operations, optical instability, and difficulty in decapsulation. Here, we report a simple, robust, and solvent-free biomolecule encapsulation strategy based on gallium liquid metal featuring low-temperature phase transition, self-healing, high hermetic sealing, and intrinsic resistance to optical damage. We sandwiched the biomolecules with the solid gallium films followed by low-temperature welding of the films for direct sealing. The gallium can not only protect DNA and enzymes from various physical and chemical damages but also allow the on-demand release of biomolecules by applying vibration to break the liquid gallium. We demonstrated that a DNA-coded image file can be recovered with up to 99.9% sequence retention after an accelerated aging test. We also showed the practical applications of the controllable release of bioreagents in a one-pot RPA-CRISPR/Cas12a reaction for SARS-COV-2 screening with a low detection limit of 10 copies within 40 min. This work may facilitate the development of robust and stimuli-responsive biomolecule capsules by using low-melting metals for biotechnology.

Monosymmetric Fe-N4 sites enabling durable proton exchange membrane fuel cell cathode by chemical vapor modification.

The limited durability of metal-nitrogen-carbon electrocatalysts severely restricts their applicability for the oxygen reduction reaction in proton exchange membrane fuel cells. In this study, we employ the chemical vapor modification method to alter the configuration of active sites from FeN4 to the stable monosymmetric FeN2+N'2, along with enhancing the degree of graphitization in the carbon substrate. This improvement effectively addresses the challenges associated with Fe active center leaching caused by N-group protonation and free radicals attack due to the 2-electron oxygen reduction reaction. The electrocatalyst with neoteric active site exhibited excellent durability. During accelerated aging test, the electrocatalyst exhibited negligible decline in its half-wave potential even after undergoing 200,000 potential cycles. Furthermore, when subjected to operational conditions representative of fuel cell systems, the electrocatalyst displayed remarkable durability, sustaining stable performance for a duration exceeding 248 h. The significant improvement in durability provides highly valuable insights for the practical application of metal-nitrogen-carbon electrocatalysts.

Effect of combined additions of Sc, Zr and Ti on hot-cracking resistance and precipitation behaviour in Al-Mg alloy by L-PBF

The request for high-performance aluminum components prompts research into innovative alloys compatible with laser-based additive manufacturing processes, leveraging grain refiners in their composition to mitigate hot-cracking and enhance strength. While the addition of Sc and Zr in Al-Mg alloys has been widely investigated, the high cost and supply risks associated with Sc necessitate reducing its amount and replacing, at least partially, with other inoculants. In this preliminary study, the amount of Sc replaceable with different concentrations of Zr or Ti is evaluated investigating the laser powder bed fusion processability of three powder feedstocks: a pre-alloyed Al-Mg-Zr-Sc powder, a blend of the previous alloy with addition of Zr particles, and a further blend of an alloy depleted of Zr with added Ti particles. The experimental analyses on the laser-processed alloys showed that the standard and the Zr-enriched alloys featured a bimodal microstructure free from cracks with fine equiaxed grains at the edge of the molten pools and coarser grains at their centers. In the alloy variant depleted in Zr with addition of Ti particles a columnar structure was observed and hot-cracks appeared. Thermodynamic simulations of phase formation allowed defining the precipitation kinetics during solidification and direct aging, showing increased precipitation in alloys with higher Zr content, while the presence of Ti resulted in sluggish precipitation. Experimental aging tests demonstrated significant increases in microhardness, with peak values of the modified alloys achieved after 12 h at 375 °C.

On the Durability Performance of Two Adhesives to Be Used in Bonded Secondary Structures for Offshore Wind Installations.

The development of offshore wind farms requires robust bonding solutions that can withstand harsh marine conditions for the easy integration of secondary structures. This paper investigates the durability performance of two adhesives: Sikadur 30 epoxy resin and Loctite UK 1351 B25 urethane-based adhesive for use in offshore wind environments. Tensile tests on adhesive samples and accelerated aging tests were carried out under a variety of temperatures and environmental conditions, including both dry and wet conditions. The long-term effects of aging on adhesive integrity are investigated by simulating the operational life of offshore installations. The evolution of mechanical properties, studied under accelerated aging conditions, provides an important indication of the longevity of structures under normal conditions. The results show significant differences in performance between the two adhesives, highlighting their suitability for specific operating parameters. It should also be noted that for both adhesives, their exposure to different environments (seawater, distilled water, humid climate) over a prolonged period showed that (i) Loctite adhesive has a slightly faster initial uptake than Sikadur adhesive, but the latter reaches an asymptotic plateau with a lower maximum absorption rate than Loctite adhesive; and (ii) a progressive deterioration in the tensile properties occurred following an exponential function. Therefore, aging behavior results showed a clear correlation with the Arrhenius law, providing a predictive tool for the aging process and the aging process of the two adhesives followed Arrhenius kinetics. Ultimately, the knowledge gained from this study is intended to inform best practice in the use of adhesives, thereby improving the reliability and sustainability of the offshore renewable energy infrastructure.

Synthesis of stable fluorescent ethylene-vinyl acetate copolymers based on in-situ grafted rare-earth organic complexes and antioxidants through transesterification

The synthesis and application of rare earth organic complexes (REOCs) are gaining attention due to their advantages including low excitation thresholds and high luminescence efficiencies. However, their integration as functional fillers in polymer matrices is constrained by challenges related to poor dispersion and limited stability. This study introduces a novel method for synthesizing stable fluorescent polymers by co-grafting europium (Eu) complexes and the antioxidant 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5.5]-undecane (AO-80) onto an ethylene-vinyl acetate (EVA) matrix through an in-situ synchronous grafting strategy, aiming to address these dual challenges of poor dispersion and rapid aging. In this study, Eu complexes characterized by low excitation thresholds and high hexahydrate (EuCl3) and selected ligands - 1,10-phenanthroline (Phen), alpha-thienyl trifluoroacetone (HTTA), and 4-acetoxybenzoic acid (4-ABA). Through transesterifications, the Eu complexes were successfully grafted onto the EVA chain, achieving a uniform dispersion within the EVA matrix to form fluorescent polymers. Furthermore, the incorporation of antioxidant AO-80 as a radical scavenger can significantly mitigate fluorescence attenuation. Through detailed exploration of transesterifications under various conditions, optimal grafting rates of 11.34% for EVA with Eu complexes and 22.87% for EVA with AO-80 were achieved. The synthesized fluorescent polymers of EVA synchronously grafted with Eu complexes and AO-80 have been proven to obtain markedly improved fluorescence stability and aging resistance by outdoor aging tests. Our findings not only validate the in-situ reaction grafting method as an efficient strategy for producing polymer composites with excellent fluorescence stability but also pave the way for future research aimed at overcoming the limitations of REOCs in photovoltaic and agricultural applications.