Surface Deterioration Research Articles

Freeze-thaw resistance and deterioration mechanism of alkali-activated filling grouts prepared from full industrial solid wastes for tunnels

To promote the application of the proposed alkali-activated grout (AAG) prepared from full solid wastes in cold-zone tunnel projects located at high altitudes and latitudes, it is imperative to fully recognise its endurance to the repeated freezing and thawing in specific service scenarios. For this purpose, two groups of representative AAG were selected as subjects for this study, and a typical OPC-based grout was chosen as the control group. Freeze-thaw cycle tests were carried out on grout samples after 28 days of standard curing using the slow-freeze method to simulate the harsh service environment in cold regions. The deterioration impact of freeze-thaw cycling on the grout samples were evaluated by monitoring the changes in visual appearance, mass loss, mechanical strength, and damage coefficient after 20, 40, 60 and 80 freeze-thaw cycles. Furthermore, the deterioration mechanism of various grout samples under the action of freeze-thaw cycling was revealed by multi-technique characterization methods including X-ray diffraction (XRD), scanning electron microscope (SEM), and mercury intrusion porosimetry (MIP). The results show that at the same number of freeze-thaw cycles, the surface deterioration, mass loss and strength damage of AAG were obviously better than that of the OPC-based grout, suggesting that AAG exhibited greater resistance to freezing and thawing than the OPC-based grout. The mass loss ratio increased with the increase of the number of freeze-thaw cycles, following a roughly power function pattern. The deterioration in the flexural strength of grout samples caused by freeze-thaw cycles was more severe than the deterioration in their compressive strength. The gel products of AAG were mainly C-A-S-H and N-A-S-H, which showed stronger resistance to freeze-thaw damage than the gel products of the OPC-based grout, C-S-H and portlandite. Compared with the OPC-based grout, AAG samples possessed a denser microstructure with lower porosity and a smaller proportion of large-sized harmful pores, which was not favourable for the pore water holding and migration of during freeze-thaw cycling and the development of osmotic and frost heave stresses, thus providing better resistance to freezing and thawing. A variety of macroscopic characterisations and microstructural tests have demonstrated the good durability of AAG against the freeze-thaw cycles, which can serve as a scientific foundation for its future engineering uses.

Examining Open-Top Culverts Impact on Forest Road Surface Deteriorations via UAVs

The life and robustness of forest roads depend on their protection from the harmful effects of water coming into the road surface. In particular, the deterioration of the road surface affects the safe navigation of vehicles and traffic safety. This situation requires that the surface be stable on forest roads. The aim of the study is to examine whether surface deterioration (erosion and accumulation) on forest roads due to the drainage problem of water falling on the road surface can be minimized by open-top culverts and to determine their effectiveness. These are used in three separate trial blocks every 25 m (A parcels; total of 3 parcels), every 50 m (B parcels; total of 3 parcels) and control block (C). Volumetric erosion and accumulation in these blocks was compared by UAV for about 3 years and the effectiveness of the open-top culverts was examined by this method. A 500 m section of the forest road coded 001 of the Kardüz Forest Operations Directorate (Düzce/Türkiye) was examined in the study. As a result, erosion and accumulation in all blocks have been found to have a dynamic course. It was determined that this mobility was greater in the control block than in the blocks with open-top culverts installed at intervals of 25 m and 50 m. The mean Z values for the blocks showed that the deterioration in the control block (C) was higher than in the blocks with 25 m and 50 m open culverts. The volumetric deterioration rate was 5 times higher in the control block than in the block installed at 25 m interval (A plots) and 2 times higher than in the block installed at 50 m interval (B plots). Similarly, the areal deterioration rate was 3.3 times higher in the control block than in the block installed at 25 m interval (A plots) and 1.4 times higher than in the block installed at 50 m interval (B plots). These results showed the effectiveness of open-top culverts and it was also determined that the open-top culverts installed at 25 m intervals were more effective than the open-top culverts established at 50 m intervals. In addition, according to the statistical analysis, a statistically significant difference was found between the erosion volume in the blocks. Open-top culverts should be used against forest road surface deterioration and UAV technology should be used for deterioration detection.

The Characterization of Natural Resins and a Study of Their Degradation in Interactions with Zinc Oxide Pigment.

In the last few years, the role of science in Cultural Heritage has assumed greater significance since diagnostics have become essential for the characterization of artworks. The development of conservation strategies involves growing the study of artworks and the knowledge of the materials used against the degradation plaguing the painted surfaces. This work focuses on the investigation of the degradation processes involving paintings on canvas, in particular delamination and progressive deterioration of the painted surfaces. The main causes of the degradation are attributable to the formation of metal soaps, which originate from the interaction between binders and pigments; as a result, the process leads to the progressive fracturing of the paint film. Using various characterization techniques allowed us to acquire information on the structural and morphological properties of the binder resins and study the binder/pigment interaction during the degradation process to understand the quantity and quality of the acid sites present in the binders and, consequently, the potential reactivity with the cationic part of the pigments. The binders were also analyzed within paint layers in contact with zinc oxide to study the interactions and the possible formation of new species as metal soaps and metal oxalates that can modify the boundary among the painting layers and, consequently, the appearance of the artwork and its artistic value. Modifications after UV and thermal aging processes were observed using Infrared spectroscopy and thermogravimetric analysis. Zinc soap formation was observed after 7 h of a UV aging process and was correlated to the acidity of the resins.

Impact of UV-B Photoaging on Chlorpyrifos Adsorption by PET Microplastics: Insights from Experimental and DFT Analysis.

Microplastics (MPs) in the environment pose a persistent concern, as these plastic particles can adversely impact both aquatic ecosystems and human health. MPs are subject to natural weathering and aging processes, such as photodegradation, which significantly alter their surface morphology and physicochemical properties, thereby influencing their fate, transport, and sorption behavior. To better understand how aging affects these properties and to elucidate the mechanisms behind the interactions with the chlorpyrifos pesticide, poly(ethylene terephthalate) (PET) microplastics (<100 μm) were subjected to accelerated photoaging in a UV-B chamber for varying exposure times. Several characterization techniques were employed, including scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD), infrared spectroscopy (IR), point of zero charge (pHPZC), and thermogravimetric analysis (TGA). Additionally, the percentage of crystallinity and carbonyl index (CI) were calculated. The results demonstrated a decrease in pHPZC following photodegradation, likely due to an increase in δ- (-C=O) groups, consistent with the CI findings. SEM revealed surface deterioration caused by aging, while TGA indicated an early thermal degradation stage associated with water volatilization, suggesting enhanced hydrophilicity. Density functional theory (DFT) calculations showed that the PET monomer absorbs slightly in the UV-B region, leading to excitation and subsequent radical reactions that form Norrish type I products. The adsorption capacity of aged PET increased compared to the pristine material, likely due to the molecular geometry becoming more planar, facilitating interactions between the aged MPs and chlorpyrifos, as confirmed by noncovalent interaction (NCI) analysis. These findings highlight the significant potential of aged microplastics to adsorb micropollutants and act as vectors in aquatic environments.

In vivo prospective randomised study of the wear of dental restorations using an intraoral scanner and its correlation with visual assessment.

Objectives: To evaluate the efficacy of the True Definition®intraoral scanner in quantifying the wear of the glass ionomer restorative material (KetacTM Universal and KetacTM Molar) over 1 year. We also studied the correlation between visual and digital assessments of restoration wear. Materials and Methods: This was a clinical follow-up study of a post-marketed material with a prospective, controlled, randomised, split-mouth, and blinded assessment design. Intraoral optical impression and visual assessment were carried out over three appointments over 12 months, starting with 36 patients.Results: According to the visual indices, all restorations in this study were clinically healthy. However, in the digital measurement of wear, 94.74% and 94.44% of the restorations during the T0-T6 and T6-T12 observation periods, respectively, showed deterioration greater than 41 microns. Moreover, in the analysis of agreement between measurement techniques, no agreement was obtained in the two analysed time periods: T0-T6 yielded a kappa (k) value of 0.000, and T6-T12 yielded k=0.0030. Discordant results were obtained in the correlation analysis. In T0-T6, the results were not considered statistically significant (p=0.838); however, the results obtained during T6-T12 showed a correlation (p-value <0.001).Conclusions: The wear of dental materials as observed by the human eye did not agree with that observed by intraoral scanning. The scanner effectively measures wear, detecting details that are beyond the capability of the human eye and conventional photographs. The surface deterioration of the restorations at both observation times can be considered non-physiological, potentially leading to premature occlusal alterations and accelerated physiological ageing.Clinical Relevance: Early diagnosis is crucial for avoiding alterations in the function of the stomatognathic system due to the wear of dental restorations. Additionally, since most of the tools applied are qualitative in nature, such as visual inspection, it is essential to find a standardised and precise tool that offers diagnosis, monitoring, and records of the evolution of tooth wear. This study has been registered at https://www.ClinicalTrials.gov, under the identifier NCT06275581.

Study on infrared thermal imaging for surface deterioration investigation and evaluation of stone cultural relics based on temperature variation

This study leverages infrared thermal imaging technology to advance the field of stone cultural relics preservation by introducing a novel evaluation index—temperature variation (Tv)—that quantifies the degree of surface deterioration. Unlike previous studies that have focused primarily on detecting a single deterioration type, this study pioneered a comprehensive analysis of the interactions of multiple deterioration in stone cultural relic. A deeper understanding of the weathering mechanisms of stone cultural relics has been gained by examining the Tv on the surface of stone cultural relics during heating and cooling, and successfully relating these changes to the degree of weathering of the cultural relic. This study developed a linear fitting method for systematically assessing the degree of weathering of stone cultural relic, which is a significant improvement over traditional assessment techniques. Our approach not only enhances the accuracy and applicability of Tv as an evaluation index but also integrates environmental temperature considerations, ensuring a more reliable assessment under varying conditions. The study's findings validate the effectiveness of infrared thermal imaging in identifying deterioration types and evaluating their severity, setting a new standard for the protection and restoration of stone cultural relics.

Three-year clinical performance of direct restorations using low-shrinkage Giomer vs. nano-hybrid resin composite

ObjectivesThe objective of this investigation was to compare the clinical performance of a nano-hybrid resin composite and a low-shrinkage Giomer resin composite.Material and methodsIn total, 35 pairs of restorations were performed using either low-shrinkage Giomer (Beautifil II LS, Shofu Inc.) or nano-hybrid (Clearfil Majesty Posterior) resin composite in 35 patients by two operators using the relevant adhesives, i.e., FL-Bond II (Shofu Inc.) and Clearfil SE Bond (Kuraray), with the self-etching technique according to each manufacturer's instructions. Two clinicians assessed the restorations 2 weeks (baseline); 6 months; and 1, 2, and 3 years after the restorative procedures using FDI (World Dental Federation) criteria (Scores 1–5). Data were analyzed using the marginal homogeneity and McNemar tests. The survival rate was calculated using Kaplan–Meier survival analysis and the survival of the two groups was compared with the log-rank test (p = 0.05).ResultsThe mean observation period was 37.7 ± 6.8 months. All restorations completed their 3-year follow-up. The criteria were mainly rated with high (1 or 2) scores for quality in both groups. Only one restoration in the low-shrinkage Giomer resin composite group was accepted as a failure at the 2-year recall due to retention loss.ConclusionAt the 3-year follow-up, the performance of the restorations using the Giomer and the nano-hybrid resin composite were similar and clinically acceptable.Clinical relevanceThe low-shrinkage Giomer resin composite exhibited a similar clinical performance to the nano-hybrid resin composite after 3 years in service with both materials displaying minor surface deteriorations at the 3-year recall.Clinical Trial Registrationhttps://clinicaltrials.gov, identifier: NCT02823769.

Investigating the erosive wear characteristics of AISI 420 martensitic stainless steel after surface hardening by boriding

Erosive wear degrades industrial components, causing surface deterioration and material loss. Understanding and mitigating this wear enhances component longevity and efficiency. Little research has been conducted to investigate the influence of particle angle, speed, and concentration on boronized surfaces. Therefore, in this study, the erosive wear behaviors of raw and boronized AISI 420 martensitic stainless steels were investigated. The samples were subjected to erosive wear testing using SiO2 abrasive particles with impact velocities of 2, 4, and 6 m/s, impact angles of 30°, 60°, and 90°, and concentration values of 5%, 10%, and 15% by weight in an abrasive sand slurry environment. Experimental runs were designed using the Taguchi L9 method. The wear test results were analyzed in terms of mass loss, surface roughness, and temperature change of the boronized and raw AISI 420 samples before and after the test. The results showed that the impact speed and concentration were statistically significant parameters compared with the impact angle, which had a negligible effect. Furthermore, with increasing impact speed and concentration, all measured responses increased in both sample groups. The surface roughness values and mass loss increased by lower margins for the boronized samples (58.40% and 188.49%, respectively) compared to those of the raw samples (61.40% and 254.38%, respectively). This study demonstrates the potential of boriding as a surface treatment technique for enhancing the erosive wear performance of martensitic stainless steels, which require improved durability and longevity of materials subjected to erosive environments.

Multi-Technique Approach for the Sustainable Characterisation and the Digital Documentation of Painted Surfaces in the Hypogeum Environment of the Priscilla Catacombs in Rome

The purpose of this paper is to identify an efficient, sustainable, and “green” approach to address the challenges of the preservation of hypogeum heritage, focusing on the problem of moisture, a recurring cause of degradation in porous materials, especially in catacombs. Conventional and novel technologies have been used to address this issue with a completely non-destructive approach. The article provides a multidisciplinary investigation making use of advanced technologies and analysis to quantify the extent and distribution of water infiltration in masonry before damage starts to be visible or irreversibly causes damage. Four different technologies, namely Portable Nuclear Magnetic Resonance (NMR), Audio Frequency–Acoustic Imaging (AF–AI), Laser-Induced Fluorescence (LIF), Infrared Thermography (IRT), and 3D Laser Scanning (RGB-ITR), were applied in the Priscilla catacombs in Rome (Italy). These imaging techniques allow the characterisation of the deterioration of painted surfaces within the delicate environment of the Greek chapel in the Priscilla catacombs. The resulting high-detailed 3D coloured model allowed for easily referencing the data collected by the other techniques aimed also at the study of the potential presence of salt efflorescence and/or microorganisms. The results supply an efficient and sustainable tool aimed at cultural heritage conservation but also at the creation of digital documentation obtained with green methodologies for a wider sharing, ensuring its preservation for future generations.

Evaluating the impact of rail surface roughness post-grinding: An experimental and elastoplastic modelling approach

Grinding is regularly conducted on railway tracks to prevent crack propagation and surface deterioration. However, grinding can introduce roughness on rail surfaces, potentially leading to stress and strain concentration that increase the likelihood of crack initiation. This paper proposes the utilization of surface roughness obtained by replicating the ground rail surface to assess its impact on train wheel-rail interactions. A novel approach which integrates the replicated roughness into an elastoplastic contact model, allows for a detailed assessment of its effects on contact pressure, and residual strain and stress distributions. The findings highlight the importance of considering surface roughness in predictive maintenance planning for railway infrastructure, as it can significantly influence the structural integrity and long-term performance of the track system.

Synthesis of bio-based nanolubricant using bimetallic nanoparticles to mitigate the surface deterioration of low carbon steel for metalforming industry

Worldwide industries are drawing their attention to the usage of bio-based substances for their operational purposes. Herein, the bimetallic nanoparticles (Bi-MNPs) were synthesised using a unique combination of Zn–Cr in bio-based mustard oil by green route utilizing wet chemical approach. Synthesised Bi-MNPs (0.12–0.15 wt%) were employed in the synthesis of bimetallic bio-based nanolubricant (Bi-BNL), and the impact was also evaluated on low carbon steel (grade SAE1006). The reduction of Bi-MNPs was carried out by green reducing agents and their stabilisation was confirmed by Fourier transform infrared spectroscopy (FTIR). Whereas, the synthesis of Bi-MNPs was followed by Surface plasma resonance (SPR), average size of Bi-MNPs which was about 60 nm and morphology was established using Scanning electron microscopy (SEM). The efficiency of Bi-BNL and impact of Bi-MNPs on the stability of Bi-BNL was investigated by Dynamic light scattering (DLS), Zeta potential (ZP) and comparative study was carried out with reference lubricant. Interestingly, the kinematic viscosity (KV) values of the lubricants are quite compatible, and have linear relationsip with coefficient of friction which is very suitable to conclude the anti-friction and anti-wearing properties. The KV of bio-based oil was monitored under the criteria of standard test method ASTM D445, and the resultant value was compared with the reference oil. The stability of Bi-BNL and its interaction with low carbon metal sheet was also studied; the outcomes were very impressive due to no rust patches, oil spots and surface deterioration on the metal sheet. The paramount creativity of this research work is the modification of bio-based oil via Bi-MNPs for the synthesis of Bi-BNL that offers the best surface quality of low-carbon steel. Cumulatively, these findings of Bi-BNL could be open up new possibilities to explore the bio-based synthesis of lubricants on a comprehensive scale.

A data-based and physics-informed Bayesian updating method for deterioration models of RC structures in marine environment

Deterioration models of reinforced concrete (RC) in marine environment, to be applied to existing structures, usually need to be calibrated with long-term in-situ data. The Bayesian model updating provides a framework to incorporate measured data into existing models to make them more realistic. The measured chloride concentrations of concrete at different depths are related to each other through the Fick’s second law, but they are treated as independent in existing updating methods, which affects the accuracy of model updating. To solve this issue, this paper proposes a data-based and physics-informed (DBPI) likelihood function to incorporate the physical law behind the measured data into Bayesian updating framework, whose validity is first confirmed through numerical examples, and then it is applied to the durability assessment of an existing wharf structure in marine environment. The parameters involved in the chloride ingress model and the critical chloride concentration model are updated using the data from durability inspections. The durability performance of the structure is then assessed using the updated models, which is consistent with the actual surface deterioration observed in the two inspections. Discussion of the updated results reveals that ignoring the physical law behind the measured data may result in incorrect inferences of the chloride ingress model and multi-mode distribution of the updated parameters, which is solved by using the proposed DBPI likelihood function, and the accuracy of Bayesian updating is significantly improved.

Historic Built Environment Assessment and Management by Deep Learning Techniques: A Scoping Review

Recent advancements in digital technologies and automated analysis techniques applied to Historic Built Environment (HBE) demonstrate significant advantages in efficiently collecting and interpreting data for building conservation activities. Integrating digital image processing through Artificial Intelligence approaches further streamlines data analysis for diagnostic assessments. In this context, this paper presents a scoping review based on Scopus and Web of Science databases, following the PRISMA protocol, focusing on applying Deep Learning (DL) architectures for image-based classification of decay phenomena in the HBE, aiming to explore potential implementations in decision support system. From the literature screening process, 29 selected articles were analyzed according to methods for identifying buildings’ surface deterioration, cracks, and post-disaster damage at a district scale, with a particular focus on the innovative DL architectures developed, the accuracy of results obtained, and the classification methods adopted to understand limitations and strengths. The results highlight current research trends and the potential of DL approaches for diagnostic purposes in the built heritage conservation field, evaluating methods and tools for data acquisition and real-time monitoring, and emphasizing the advantages of implementing the adopted techniques in interoperable environments for information sharing among stakeholders. Future challenges involve implementing DL models in mobile apps, using sensors and IoT systems for on-site defect detection and long-term monitoring, integrating multimodal data from non-destructive inspection techniques, and establishing direct connections between data, intervention strategies, timing, and costs, thereby improving heritage diagnosis and management practices.

The Surface Deterioration of Prefabricated Zirconia Crowns on Exposure to Acidulated Phosphate Fluoride Gel: An In Vitro Study.

Introduction Zirconia is a widely used restorative material in dentistry due to its superior aesthetic and mechanical properties. The oral cavity is a complex ecosystem with various components, which affect the teeth, as well as artificial restorative materials. Various personal and professional interventions carried out can severely affect the properties of restorative materials, thus altering the longevity of the prosthesis; 1.23% acidulated phosphate fluoride (APF) gel is one such professionally applied topical fluoride agent used to prevent caries. The interaction of this APF gel with highly aesthetic restorative material such as zirconia crowns is unknown. Objective The objective of this study is the evaluation of the surface deterioration of prefabricated zirconia crowns on exposure to deionised water and 1.23% acidulated phosphate fluoride (APF) gel with field emission scanning electron microscope (FE-SEM) and mass loss analysis. Material and method Sixty prefabricated paediatric zirconia crowns were taken, 10 samples were immersed in deionised water, 40 samples were immersed in 1.23% APF gel and 10 samples were used ascontrol. Surface morphology and mass loss analysis were carried out at time intervals of four minutes, 24 hours, 48 hours and 72 hours using FE-SEM and digital weighing machine. Results No visual change was observed in the samples immersed in deionised water at the time interval of 72 hours. There was a marked visual change in samples immersed in 1.23% APF gel at the time interval of four minutes to 72 hours; this change involved a loss of gloss to the appearance of chalkiness. FE-SEM analysis for the control group and samples immersed in deionised water showed a smooth, continuous, undisrupted top layer, while samples immersed in 1.23% APF gel showed changes ranging from surface etching, to pinhole porosities, to crack formation and disruption of the surface depending upon the exposure time. Conclusions On the immersion of zirconia crowns in an aqueous acidic medium of 1.23% APF gel, the crowns showed flaws, imperfectionsand uneven superficial layers. It has been observed that surface grains are disrupted and micropores have been formed. This degraded superficial surface when undergoes cyclic mechanical loading can accelerate the ageing phenomenon of zirconia. Mechanical forces along with a dynamic electrochemical environment can degrade the material properties of zirconia.

Insight into anti-corrosion behavior of Cladanthus mixtus (L.) flower extracts as a biodegradable inhibitor for carbon steel in acid medium: Experimental and theoretical studies

This study conducted a comprehensive investigation into the corrosion inhibition potency of the essential oil of flowers (EOF) and the aqueous extract of flowers (AQEF), a by-product liquid waste derived from the extraction process of Clandanthus mixtus (L.), towards carbon steel in 1 M HCl. Phytochemical screening, gas chromatography (GC), and gas chromatography coupled to mass spectrometry (GC-MS) were employed to explore the chemical composition of the extracts. Flavonoids, tannins, and coumarins were identified as chemical families present in the extracts, while palmitic acid (10 %) and arcurcumene (39.1 %) were found to be the most important constituents, comprising 49.1 % of the total composition of the essential oil. Electrochemical techniques, including Tafel extrapolation methods and electrochemical impedance spectroscopy (EIS), were used to evaluate the inhibition efficiency of the extracts. The inhibition efficiencies reached a maximum of 80 % following a mixed-type inhibition mechanism. The temperature effect was evaluated, revealing a physisorption process followed by desorption at higher temperatures. The synergistic effect between the extract and potassium iodide was assessed at different doses, demonstrating their cooperative role in reducing steel surface deterioration. Surface micrographs were acquired through scanning electron microscopy (SEM) with the Energy Dispersive X-ray (EDX) method in the presence of AQEF, confirming the establishment of a protective barrier that mitigates the corrosive effects of hydrochloric acid. Additionally, this study employed Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations to investigate the behavior of AQEF compounds against corrosion.

Native and TMT Chestnut Extractives as Hydrophobic and Photostabylizing Additives for Wood Surfaces

Wood extractives have proven strong anti-oxidative properties which may be used to mitigate surface deterioration caused by photolytic effects and free radical formations. An interesting challenge regarding wood extractives is understanding how they behave in terms of treating natural wood surfaces to reduce anti-oxidative processes that arise from exposure to the main environmental factors. In this study, the possible efficacy of chestnut (Castanea sativa Mill.) extractives derived from native (CH) and thermally modified wood (TMT CH), as a means of protecting against UV exposure in poplar (Populus spp.) and spruce (Picea abies Karst.) wood, was evaluated. Chestnut wood was first thermally modified at 180 °C for 3 h, and the extractives were obtained by the accelerated solvent extraction technique (ASE) and subsequently used to treat wood surfaces. Samples were immersed in extractive solutions and exposed to artificial UV-weathering exposure, then contact angle and colour stability were monitored during the process. An FTIR analysis of the photo-degradation process of poplar and spruce surfaces was also executed. Extractives of TMT chestnut changed the total colour variation in both poplar and spruce wood. A much darker colour compared to the extractives of native wood was observed and an increase in ∆E* from 9.75 to 30.76 and 6.24 to 22.97 in poplar and spruce was calculated. The stability of the colour depended both on the surface wood and the type of extractive. The initial contact angle remained almost unchanged in the poplar wood surface and only slightly increased in spruce regardless of whether they were treated with extractives from native or TMT chestnut wood. A strong reduction in contact angle after the accelerated UV exposure test was observed, especially in spruce treated with CH extractives. FTIR analysis confirmed the lower levels of chemical degradation of surfaces observed by colorimetry, where TMT CH extractives formed more stable chemical bonds than native extractives. The comparative analysis in this study clarified the complex relationships between the effects of high-temperature modification of wood and the potential protective role of TMT extractives on some wood surfaces.

The impact of ecological aging on the mechanical performance of jute-banana fibre phenol-formaldehyde hybrid composites

Natural fiber composites provide an environmentally favorable and sustainable alternative to traditional materials, greatly reducing environmental impact. Aging tests are required to evaluate the long-term mechanical performance and durability of these composites under varied situations, ensuring their dependability and safety over time. This study investigates the effects of ecological aging on jute-banana fiber reinforced phenol-formaldehyde (JBP-F) composites. The experiment involved fabricating JBP-F composites using jute and banana fibers with varying weight ratios (60:40, 50:50, 40:60, 30:70) and subjecting them to various aging tests like long-time water resistance, accelerated water resistance, thermal aging, hydrothermal aging, soil burial test, and accelerated weathering test. The result showed that the composite with a 50:50 jute-banana fiber to resin ratio (JBP-F50) outperformed the other compositions examined in terms of aging resistance. This balanced ratio likely optimized fiber-matrix interaction, leading to superior strength and water resistance. Higher fiber content composites (like JBP-F60) absorbed more water due to weaker bonding, while lower fiber content (JBP-F30) suffered more in high temperatures. All composites experienced strength loss during thermal and hydrothermal aging due to heat and moisture cycles. JBP-F50 again showed the least degradation, possibly due to the resin’s ability to recover. In soil burial tests, biodegradation impacted strength, with higher fiber content composites (JBP-F60) degrading more. Finally, weathering tests revealed some surface deterioration due to UV radiation. However, the resin offered protection, with JBP-F30 (higher resin content) experiencing the most weight loss.JBP-F50, with its balanced fiber-resin ratio, demonstrated the best resistance to various environmental stresses, making it a promising option for sustainable composite applications.

Hydrovoltaic–piezoelectric hybridized device for microdroplet-pressure dual energy harvesting and piezo sensing

Previous droplet-based nanogenerators have made significant advancements in mechanical energy harvesting from liquid–solid contact electrification. However, these generators still face certain issues, such as neglecting substrate deformation energy, inability to store energy, and surface deterioration due to continuous impact of droplets, thus narrowing the scope of their potential applications. Here, a novel hydrovoltaic-piezoelectric hybridized device (HPeD) is reported that integrates hydrocapacitor, aluminum–air (Al–air) battery, and piezoelectric nanogenerator technologies through a green design strategy, which can effectively address the proposed problems. Impinged by a 40-μL water droplet, the HPeD yields a potential window of 1.54 V within approximately 1 min, further boosting to 1.86 V under external vertical pressure. The generated energy was greatly stored for up to 5.7 days. This all-solid-state device effectively inhibits electrolyte leakage during idle periods and controls reversible reactions to minimize corrosion, thereby extending its lifespan. Furthermore, the HPeD is successfully used as a piezoelectric nanogenerator/sensor that can operate continuously to detect external mechanical stimulus. In piezo sensor mode, the device demonstrated good sensitivity of 0.098 kPa−1 in the low-pressure range (0–8.2 kPa), a remarkable response/relaxation time of 0.3 s, and durability lasting over 8000 cycles. This study paves the way for the advancement of next-generation flexible hybrid devices capable of multifunctionality in both energy harvesting and sensing.

High voltage electrochemical performance of ultrahigh-Ni cathode via in situ constructed nano-LiF and CNT composite cathode electrolyte interphase layer

Ultrahigh-nickel LiNixCoyMn1-x-yO2 cathode material (Ni content ≥ 0.9) is of great significance for the development of high energy density of lithium-ion batteries. However, its high surface activity leads to more surface residual lithium formation and deterioration of electrochemical performance, especially at high voltage. Here we add NH4F and nitrogen-doped carbon nanotubes (CNT) during the dimethyl carbonate (DMC) washing process, and constructed in situ the nano-LiF and CNT composite cathode electrolyte interphase (CEI) layer while removing part of residual lithium, effectively optimizing the surface environment of LiNi0.9Co0.05Mn0.05O2. The modified LiNi0.9Co0.05Mn0.05O2 has a capacity retention rate of 61.3 % after 200 cycles between 2.8 and 4.5 V at 1C, significantly higher than the 46.7 % of the unwashed sample, and a specific discharge capacity of 146.9 mAh g−1 at 5C, compared to 127.5 mAh g−1 for the unwashed sample. Benefit from the alleviation of polarization and the increase of Li+ diffusion coefficient, the stable CEI layer provides effective protection for LiNi0.9Co0.05Mn0.05O2 under 4.5 V, alleviating surface side reactions. In this paper, a simple and effective strategy is developed to optimize the surface of Ni-rich cathode material, which provides a new insight for the treatment of surface residual lithium.

SIMULATION OF SPATIO-TEMPORAL DYNAMICS OF STREAM FLOW TO CLIMATE VARIABILITY IN NJORO RIVER CATCHMENT, KENYA

Climate variability continues to alter hydrological regimes and the response of many catchments globally thus threatening water security. Njoro River Catchment has not been an exception. There is a steady recognition of climate variability and adverse influences like deterioration of ecosystems, surface, and groundwater sources. Therefore, the study focused on modelling the impact of climate variability on the spatial and temporal distribution of stream flow in the Njoro River Catchment, Kenya. Modelling of stream flow response to climate variability using SWAT was carried out based on USGS/NASA downloaded Digital Elevation Model, FAO soil data, Landsat (MSS 1-5) LULC of 1978, and meteorological data for the period (1978 - 2017). Simulation of spatial and temporal impacts of climate variability was then carried out. Based on the analysis, SUFI-2 algorithm results revealed that the most sensitive parameter in Njoro River Catchment is SCS curve number for antecedent moisture condition (II) (CN2), ranked according to the highest sensitivity tested at p &lt; 0.05. The least sensitive parameter is maximum canopy storage (CANMX). Overall uncertainty analysis results showed a good performance value of P-factor (0.72) and R-factor (0.38), which indicated that SWAT reproduced the dynamics of the catchment hydrologic response relatively well. The values of R2, NSE, and PBIAS for calibration and validation of monthly stream flow were 0.88 and 0.77, 0.86 and 0.74, and 5.51 % and -15.42 % respectively. From the spatio-temporal impacts of climate variability on hydrologic variables, actual evapotranspiration increased by about 5.6 %, 3 %, and 6.62 % in the 2nd, 3rd, and 4th decades. Surface runoff decreased in the 2nd decade by 34.56 % and increased by 4.55 % and 34.02 % in the 3rd and 4th decades. Annual water yield decreased in the 2nd decade by 29.69 % and increased by 4.25 % and 60.18 % in the 3rd and 4th decades respectively. On average, stream flow reduced by 30.91 % in the 2nd decade and increased by 5.47 % and 63.63 % in the 3rd and 4th decades respectively. These findings provide pertinent insights, which may perhaps enlighten decision-making in designing adaptable mitigation measures, catchment rehabilitation, and strategic initiatives for the integrated management of water resources.