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Purpose: To describe and compare the race characteristics, demands, and durability profile of a male and a female Grand Tour winner. Methods: Overall and stage-type-specific (ie, time trials, flat, semimountainous, and mountain) demands and race characteristics during 2 Grand Tours were determined and compared between the female and male cyclists. In addition, relative power output distribution and pacing, percentage of functional threshold power (FTP), and changes in maximal mean power outputs (MMPs) with increasing levels of kilojoules burned were determined. Results: Although many differences were found between course and absolute racing demands between the male (FTP: 413 W; critical power: 417 W) and female (FTP: 297 W; critical power: 297 W) cyclists, similar power distributions and pacing strategies were found if data were expressed relatively. However, the female cyclist rode a higher percentage of her FTP during the first 2 quarters of flat stages (14.7%–15.1%) and the last quarter of mountain stages (9.8%) than the male cyclist. Decrements in MMPs were only observed after burning 30 kJ·kg−1 in the female and 45 kJ·kg−1 in the male Grand Tour winner. Conclusions: Both the male and female Grand Tour winners produced very high 20- to 60-minute MMPs, whereas decrements in MMPs were only observed after having burned 75% (female) and 80% (male) of total kilojoules burned during a stage. These are the latest and lowest in MMPs reported in the scientific literature and highlight the importance of durability in combination with excellent climbing and time-trial skills, which are needed to be able to win a Grand Tour. [ABSTRACT FROM AUTHOR]

In the face of a threat to democratic rule, a Brazilian electoral court barred its former president, Jair Bolsonaro, from holding office for eight years. Unfortunately, the United States lacks a similar electoral court to protect the integrity of the electoral process—in fact, our electoral system is organized in such a way that it invites attacks on its integrity. These problems in design can be traced back to the US Constitution, which, notwithstanding its durability and historical greatness, suffers from certain defects that leave the United States vulnerable to democratic back-sliding. Principal defects include the method of presidential elections via the Electoral College, the two-senator-per-state rule in the upper chamber of Congress, and, perhaps most damaging of all, the method for amending the Constitution. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced via water electrolysis using renewable electricity, will play a crucial role in decarbonizing industrial and heavy-duty transportation sectors. Anion exchange membrane water electrolyzers (AEMWEs) can overcome many of the performance and cost limitations of incumbent technologies, however, still suffer from durability challenges due to oxidative instability of anion-exchange ionomers. Herein, the use of an electro-active porous transport layer as anode (PTL-electrode) is demonstrated to enable efficient and durable AEMWEs. The stainless-steel PTL-electrodes are shown to have superior performance and durability compared to traditional catalyst layers containing ionomer and nanoparticle catalysts. An AEMWE cell operating at 2 A cm−2 for over 600 h exhibited a degradation rate of just 5 µV h−1. During operation, the surface composition of the stainless steel transforms into a mixture of iron and nickel oxyhydroxides, contributing to enhanced oxygen-evolution reaction activity. The combination of experimental work and modeling elucidates how the bulk structure of the PTL-electrode offers an additional design dimension to further improve electrolyzer performance. Lastly, a surface modification strategy is applied to a PTL-electrode to achieve an even higher performing AEMWE (2.3 vs 2.0 A cm−2 at 1.8 V). Overall, this work lays out pathways toward more efficient, durable, and affordable AEMWEs.

Heat exchangers are made of metals because of their high heat conductivity and mechanical stability. Metal surfaces are inherently hydrophilic, leading to inefficient filmwise condensation. It is still a challenge to coat these metal surfaces with a durable, robust, and thin hydrophobic layer, which is required for efficient dropwise condensation. Here, we report the nonstructured and ultrathin (∼6 nm) polydimethylsiloxane (PDMS) brushes on copper that sustain high-performing dropwise condensation in high supersaturation. Due to the flexible hydrophobic siloxane polymer chains, the coating has low resistance to drop sliding and excellent chemical stability. The PDMS brushes can sustain dropwise condensation for up to ∼8 h during exposure to 111 °C saturated steam flowing at 3 m·s-1, with a 5-7 times higher heat transfer coefficient compared to filmwise condensation. The surface is self-cleaning and can reduce the level of bacterial attachment by 99%. This low-cost, facile, fluorine-free, and scalable method is suitable for a great variety of heat transfer applications.

Abstract: The aim of this study is to enable the hydrogen economy and decarbonize various sectors in our environment that requires less expensive and more durable water electrolyzers, which can meet the Hydrogen-Shot target. The key is to improve the ionomer interfaces in low-temperature water electrolyzers as rapidly as possible, but to do so, it requires a systematic and holistic campaign combining both experiments and theory. In this perspective, we discuss the issues of electrolyzers and needs for translational science. We then present the approach that the Energy EarthShot Research Center: Center for Ionomer-based Water Electrolysis is taking in hopes of inspiring the community with this approach that can be leveraged to multiple problems and technologies. Graphical abstract: (Figure presented.) Highlights: One way to achieve the Hydrogen-Shot goal of low-cost, clean hydrogen, is advancing research and development on the interfaces of water electrolyzers for both performance and lifetime. The Center for Ionomer-based Water Electrolysis is exploring new techniques and strategies to not only interrogate interfacial phenomena in water electrolyzers to increase efficiency and durability, but also a new paradigm related to synergistic, cojoined experimental and theoretical research. Discussion: Catalyst\ionomer interfaces are complex and not fully understood, but through investigating different interfaces and utilizing digital and physical twins, we can elucidate key mechanisms and understanding. Understanding the dynamic double layer in electrochemical systems that use solid electrolytes is crucial to identifying and mitigating the controlling phenomena to enable increased performance and durability at the technology level. Studying the time and length scales of interfacial changes can be a powerful tool to understand reaction mechanisms and changes in the electrolyzer performance and durability.

Proton exchange membrane fuel cells (PEMFCs) are expected to play a pivotal role in decarbonizing the transportation sector, and particularly heavy-duty vehicles (HDVs). However, improvements in durability are needed for PEMFCs to compete with state-of-the-art power sources for HDVs. Here, we examine how catalyst layer (CL) cracks that are engineered affect the CL durability by using patterned silicon templates to control the CL crack density at the micrometer scale. Electrochemical analyses show that the initial PEMFC performance is relatively unaffected by crack density, but the performance after durability testing was strongly affected. Specifically, CLs with high crack density showed higher performance relative to CLs without cracks after application of a carbon corrosion accelerated stress test. Electrochemical analyses coupled with X-ray computed tomography and scanning transmission electron microscopy with energy dispersive X-ray spectroscopy showed that the cracks provide shorter oxygen diffusion pathways to reaction sites, leading to decreased oxygen transport resistance. Additionally, we observed that the catalyst durability is unaffected by cracks. Our results provide a mechanistic explanation of the role of cracks in CL durability.

Reversible solid oxide cells (RSOCs) are highly efficient energy conversion devices for electricity generation and hydrogen production. However, their commercialization is significantly hindered by the slow oxygen reduction/evolution reaction (ORR/OER) activity of oxygen electrodes and the insufficient durability of the RSOCs. Herein, an active and durable PrBa 0.8 Ca 0.2 Co 1.5 Fe 0.5 O 5+ δ –Ce 0.8 Gd 0.2 O 2-δ (PBCCF–GDC) composite oxygen electrode with mediate thermal expansion is developed, achieving a low polarization resistance of 0.058 Ω cm2 at 750 °C. The PBCCF–GDC oxygen electrode has been applied and evaluated in both the button cell (Φ = 20 mm) and large-area cell (10 × 10 cm2), respectively. When utilized as an oxygen electrode in button cell, it achieves a peak power density of 0.88 W cm−2 in the fuel cell (FC) mode, and a current density of −1.51 A cm−2 at 1.3 V with 70% H 2 O in the electrolysis cell (EC) mode at 750 °C, and favorable stability in the both FC and EC modes. When utilized in large-area cell, it exhibits a power of 29.5 W and good stability over 330 h, and an impressive electrolysis current of −27A at 1.3 V with 70% H 2 O at 750 °C. The results indicate that PBCCF–GDC is a promising oxygen electrode material for RSOCs. [Display omitted] • Button and large-area cells with PBCCF–GDC composite oxygen electrode are prepared. • The PBCCF–GDC oxygen electrode exhibits excellent ORR/OER activity. • The large-area cells exhibit good durability in both FC and EC modes at 750 °C. • The scalability of PBCCF–GDC oxygen electrode in large-area RSOCs is proved. [ABSTRACT FROM AUTHOR]

Proton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production, although its widespread development with state‐of‐the‐art loadings is threatened by the scarcity of iridium (Ir). Homogeneous dispersion of Ir in an immiscible electro‐ceramic matrix can enhance catalytic mass activity and structural stability. The study presents IrySn0.9(1−y)Sb0.1(1−y)Ox solid solutions produced by highly scalable flame spray pyrolysis (FSP) process as efficient anode electrocatalysts for PEMWE, containing only 0.2 mg cm−2 of Ir in the catalyst layer (CL). Intense mixing of metal vapor and large thermal gradients in the precursor‐derived high‐temperature flame aids stabilizing sub‐nanoscale entropic mixing within self‐preserved 4–6 nm particles. Detailed investigations confirm that the one‐step prepared solid solution electrocatalysts exhibit up to fourfold higher activity toward the oxygen evolution reaction (OER) compared to Ir black. The anode of a PEMWE utilizing this catalyst exhibits high performance and stability over 2000 h but with tenfold lower Ir loading than the state‐of‐art. [ABSTRACT FROM AUTHOR]

Direct electrochemical seawater splitting is a renewable, scalable, and potentially economic approach for green hydrogen production in environments where ultra‐pure water is not readily available. However, issues related to low durability caused by complex ions in seawater pose great challenges for its industrialization. In this review, a mechanistic analysis of durability issues of electrolytic seawater splitting is discussed. We critically analyze the development of seawater electrolysis and identify the durability challenges at both the anode and cathode. Particular emphasis is given to elucidating rational strategies for designing electrocatalysts/electrodes/interfaces with long lifetimes in realistic seawater including inducing passivating anion layers, preferential OH−adsorption, employing anti‐corrosion materials, fabricating protective layers, immobilizing Cl− on the surface of electrocatalysts, tailoring Cl− adsorption sites, inhibition of OH− binding to Mg2+ and Ca2+, inhibition of Mg and Ca hydroxide precipitation adherence, and co‐electrosynthesis of nano‐sized Mg hydroxides. Synthesis methods of electrocatalysts/electrodes and innovations in electrolyzer are also discussed. Furthermore, the prospects for developing seawater splitting technologies for clean hydrogen generation are summarized. We found that researchers have rethought the role of Cl− ions, as well as more attention to cathodic reaction and electrolyzers, which is conducive to accelerate the commercialization of seawater electrolysis. [ABSTRACT FROM AUTHOR]

Geopolymer concretes have shown better resistance against alkali–silica reaction (ASR) than ordinary Portland cement concretes, which was attributed to the low pore solution alkalinity of the geopolymer. However, the alkalinity of the geopolymer pore solution depends on the concentration and volume of the activating solutions used and age of the geopolymer. The main objective of this study was to investigate the effects of pore solution alkalinity on the ASR expansion of the metakaolin‐based geopolymer concrete. The chemistry of the pore solution of metakaolin‐based geopolymer was studied, and its reaction with reactive and non‐reactive aggregates was investigated. The concrete prism expansion tests showed no ASR‐induced expansion in geopolymer despite sufficient pore solution alkalinity to attack the reactive aggregates. The SEM and XRD characterizations confirmed that no ASR‐related gel was formed during the reaction between reactive aggregates and extracted pore solution. The chemical structure of the reaction product between aggregates and pore solution was characterized using MAS NMR and revealed no difference in the reaction products with reactive and non‐reactive aggregates. The results suggest that the pore solution alkalinity is not the sole governing parameter for ASR expansion in the geopolymer. [ABSTRACT FROM AUTHOR]

Free chloride concentration distribution is important for assessing the corrosion risk of steel bars in reinforced concrete structures under chloride environment. In this study, a group of 3150 free chloride concentration data sets were obtained. Afterwards, three machine learning methods, namely support vector regression (SVR), multilayer perceptron (MLP) and one-dimensional convolutional neural network (1D-CNN) were adopted to construct models to predict chloride concentration distribution. The results show that 1D-CNN and MLP models are better at predicting the chloride concentration in fly ash concrete, whereas the prediction capability of SVR is relatively poor. Moreover, free chloride concentration prediction based on unmeasured parameters was conducted. The results show that the 1D-CNN and MLP models both have high prediction abilities – that is, predicted results are consistent with experimental measurements, performing generally better than the time-varying model constructed based on Fick's second law. When the free chloride concentrations were higher than 0.1%, the SVR model had a better prediction effect, but had unsatisfactory results and differed significantly from the actual chloride concentration when at a lower concentration. Overall, the 1D-CNN model performs the best in predicting free chloride concentration of concrete at different penetration depths, exposure time and with different fly ash content. [ABSTRACT FROM AUTHOR]

While ultra-high performance concrete (UHPC) offers numerous advantages, it also presents specific challenges, primarily due to its high cost and excessive cement content, which can pose sustainability concerns. To address this challenge, this study aims to develop cost-effective and sustainable UHPC mixtures by incorporating ground granulated blast furnace slag (GGBFS) and limestone powder (LP) as partial replacements for portland cement. Eight fiber-reinforced UHPC mixtures were investigated, with a water-to-cementitious materials (w/cm) ratio of 0.15. In four of the UHPC mixtures, 25% of the cement was replaced with GGBFS, and further, LP was added as a mineral filler, partially substituting up to 20% of the cement. In the remaining four mixtures, cement was replaced with only LP up to 20% (without GGBFS). The 28-day compressive strength of the UHPC mixture with 25% GGBFS and 20% LP was 149 MPa, 3.50% lower than the mixture without GGBFS. Its 28-day flexural strength decreased by 30%. Increasing LP replacement reduced drying and autogenous shrinkage, with a 29% shrinkage reduction at 20% LP replacement. Moreover, UHPC mixtures with GGBFS exhibited lower shrinkage compared to those without GGBFS for all LP replacements up to 20%. For evaluating the sustainability of UHPC mixtures, the cement composition index (CCI) and clinker to cement ratio (CCR) were determined. For 20% LP replacement with 25% GGBFS, CCI was 3.6 and the CCR was 0.5, 38% decrease from the global clinker to cement ratio. Overall, 20% LP replacement UHPC mixtures with and without GGBFS can produce UHPC class performance and reduce the environmental impact. [ABSTRACT FROM AUTHOR]

Existing concrete specifications limit the crack width in order to fulfill the limits of serviceability and durability. The crack width calculation results differ depending on the influences of the variability of the used materials, the geometry, the actions and the uncertainty of the used calculation model itself. In this contribution, the influence of the variability of the input parameters on the calculated crack width is investigated using probabilistic methods in a real case study of a highly loaded tunnel lining cross‐section. The primary objective of this study is a sensitivity analysis to identify the geometric and material‐related input parameters with the most significant influence, which must be particularly controlled during execution for quality control purposes. The study in this article is based on the Eurocode deterministic model for calculating crack width for a stabilized cracking stage in late concrete age. [ABSTRACT FROM AUTHOR]

Highlights Boron nitride (BN) has excellent thermal conductivity (TC), however, it exhibits high surface energy, strong chemical inertness, poor interface compatibility with polymer matrices, and difficulty in even dispersion within‐polymer matrix, preventive effective construction of TC pathways. Four kinds of modified boron nitride/polyurethane composites (BTPUC) were prepared by different silane‐functionalized BN with polyurethane (TPU). Among them, 3‐trimethoxysilylpropylmethacrylate (TMSPMA)‐functionalized BN demonstrated better interface compatibility with TPU, significantly improving the mechanical properties and TC of the composites compared to the other three functionalized BN addition. The BN@TMSPMA/PU exhibited good TC and mechanical properties, with a TC of 0.865 W/mK, a tensile stress and a tensile strain of 9.65 ± 1.40 MPa and 759.88 ± 67.93%, respectively. It also showed good electrical insulation properties and mechanical durability. Therefore, the as‐prepared BN@TMSPMA/PU have broad prospects as flexible thermal‐management materials. The composites are constructed by TMSPMA‐modified BN and polyurethane by NIPS. The composites show good mechanical properties and cyclic failure resistance. The composites exhibit good thermal conductivity and electrical insulation. [ABSTRACT FROM AUTHOR]

Recently through the synergetic utilization of triboelectrification, electrostatic induction, and electrostatic discharge, a novel dual‐functional triboelectric nanogenerator (DF‐TENG) has been developed, which can not only generate a motion‐responsible alternating current/ direct current output but also provide a higher performance compared to traditional TENGs. However, further improvements in performance and lifespan are crucial and remain challenging for the future large‐scale application of this new‐type TENG. Herein, a novel bioinspired self‐lubricating prototype is presented (BS‐TENG), which employs a porous polyurethane (PU) matrix impregnated with a low‐viscosity dielectric lubricant. In response to external mechanical stimuli, the BS‐TENG can "secrete" pre‐stored lubricant to partially fill micro‐gaps between tribo‐layers, thus forming self‐lubrication. This self‐lubricating mechanism not only elevates the electrostatic discharge threshold between tribo‐layers to maximize charge accumulation, thereby facilitating efficient energy release through electrostatic discharge for enhanced power output, but also significantly reduces material abrasion and realizes superior output durability. Benefiting from this effect, the BS‐TENG delivers an average power density of up to 4.6 W m−2, with extraordinary stability to retain 99% of its initial output even after over 60 000 cycles. This work provides a straightforward and effective strategy for realizing high‐performance and long‐stability TENGs, paving the way for their practical applications. [ABSTRACT FROM AUTHOR]

The global population is increasing, and emerging technologies have led to an unprecedented rise in worldwide energy consumption. Moreover, there is an urgent need to decrease the emission of harmful greenhouse gases linked to the utilization of fossil fuel reserves, which are depleted rapidly. In this context, polymer electrolyte membrane (PEM) fuel cells have emerged as the most promising energy source. One innovative energy system with significant potential is the direct borohydride fuel cell (DBFC), which offers a remarkable energy storage and conversion capacity. This technology has gained significant attention due to its impressive theoretical specific energy, convenient storage capabilities, and environmentally friendly characteristics. The distinctive capabilities of this technology have attracted the interest of both academic and industrial domains, owing to its versatile applicability across a broad spectrum of applications. This article provides thorough insights into the types of PEMs, catalysts, and factors limiting their practical applications in DBFCs. The mechanism of fuel oxidation, degradation, and mitigation measures of PEM in DBFCs are discussed in detail. By highlighting the notable advantages of PEMs in DBFCs, such as their permeability and minimal fuel crossover, ion conductivity, and stability, we demonstrate the significant potential of PEM membranes in DBFCs. Additionally, we have presented several representative examples that showcase the diverse range of potential applications for PEM membranes in fuel cells. Finally, we have addressed key challenges in this field, providing valuable insights for future research endeavours. • Recent advances in polymer electrolyte membranes and catalysts in direct borohydride fuel cell applications are summarized. • The working mechanism, elemental relationship, and transport coefficients are thoroughly elaborated. • Emphasis is targeted on the degradation of membranes in the long run and their mitigation strategies. • Practical viability and sustainability constraints and suggestions are also discussed. [ABSTRACT FROM AUTHOR]

Flexible humidity sensors (FHSs) with fast response times and durability to high-humidity environments are highly desirable for practical applications. Herein, an FHS based on crosslinked sodium alginate (SA) and MXene was fabricated, which exhibited high sensitivity (impedance varied from 107 to 105 Ω between 10% and 90% RH), good selectivity, prompt response times (response/recover time of 4 s/11 s), high sensing linearity (R2 = 0.992) on a semi-logarithmic scale, relatively small hysteresis (~5% RH), good repeatability, and good resistance to highly humid environments (negligible changes in sensing properties after being placed in 98% RH over 24 h). It is proposed that the formation of the crosslinking structure of SA and the introduction of MXene with good conductivity and a high specific surface area contributed to the high performance of the composite FHS. Moreover, the FHS could promptly differentiate the respiration status, recognize speech, and measure fingertip movement, indicating potential in breath monitoring and non-contact human–machine interactions. This work provides guidance for developing advanced flexible sensors with a wide application scope in wearable electronics. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of adding waste PET fibers on the mechanical properties and chloride ion penetration of latex-modified ultra-rapid hardening cement concrete used for emergency road pavement repairs. The primary experimental variable was the content of waste PET fibers. The mechanical properties of the concrete were evaluated through compressive strength, flexural strength, and splitting tensile strength tests. Its durability was evaluated through chloride ion penetration, surface resistivity, and abrasion resistance tests. The experimental results were compared with the quality standards for emergency repair concrete set by the Korea Expressway Corporation. As a result, this study has enhanced the strength and resistance to chloride ions of latex-modified concrete by incorporating waste PET fibers. In the mixture with 3.84 kg/m3 of waste PET fibers, the compressive strength was 29.9 MPa at 4 h and 42.5 MPa at 28 curing days. The flexural strength was 6.0 MPa at 4 curing hours and 7.0 MPa at 28 days, and the splitting tensile strength was 4.5 MPa at 28 days of curing. The chloride ion permeability amount and abrasion depth were 1081C and 0.82 mm, respectively. The mixture with 3.84 kg/m3 of waste PET fibers has superior compressive strength, flexural strength, splitting tensile strength, chloride ion penetration, and surface resistivity compared to the mixture with 7.68 kg/m3. This result means that the waste PET fibers caused poor dispersion and fiber-balling within the concrete, leading to loose internal void structures when incorporated at 3.84 kg/m3. However, the abrasion resistance test showed better results for the mixture with 7.68 kg/m3 of waste PET fibers than the 3.84 kg/m3 mixture. Therefore, the test results indicated that 3.84 kg/m3 of waste PET fibers is the most effective for latex-modified concrete used in emergency road pavement repairs. [ABSTRACT FROM AUTHOR]

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance. [ABSTRACT FROM AUTHOR]

The characteristics of shotcrete can lead to significant shrinkage deformation, presenting potential threats to tunnel structure safety. To research this concern, in this study the effects of three accelerators on the volume stability of cement paste, cement mortar and concrete were investigated. The correlation equations of the shrinkage deformation of cement paste, cement mortar and concrete were established, and the drying shrinkage prediction model of cement mortar with accelerator was constructed by combining the ACI 209 model and the GL2000 model. Findings from this study show that the liquid alkali accelerator AR had the greatest autogenous shrinkage and drying shrinkage, with the highest mass loss under drying conditions. The study demonstrated that there exists a good linear relationship between the shrinkage deformation of cement paste, cement mortar and concrete with accelerator. Finally, the proposed prediction model for drying shrinkage of cement mortar exhibits strong predictive capabilities. [ABSTRACT FROM AUTHOR]

Honeycomb cores are essential components of composite sandwich structures, and enhancing their ability to withstand out-of-plane loads can improve the resilience of sandwich structures under low-velocity transverse impacts. Therefore, this study computationally investigates the potential for improving the out-of-plane strength of honeycomb cores by superposing periodic sinusoidal perturbations to their cell walls. Such perturbations have been used to enhance the acoustic properties of honeycomb cores. Results demonstrated that introducing these perturbations can improve the strength of honeycomb cores under localized out-of-plane loadings resembling colliding with small objects at low impact speeds. Superposed perturbations increased the out-of-plane strength by a maximum of 28.5 % and eliminated the post-buckling softening behavior. Moreover, they increased the toughness, represented by the area under the force-displacement curve, under localized out-of-plane loads by a maximum of 56.7%. The perturbed honeycomb cores showed more sensitivity to the frequency of the superposed perturbations than their magnitude. [ABSTRACT FROM AUTHOR]

This article provides a brief description of microcapsule self-healing technique and its potential use in concrete structures. Because concrete is readily available and reasonably priced, it is widely utilised in the building industry globally, despite its susceptibility to the formation of cracks. The longevity and security of concrete buildings are greatly impacted by the existence of cracks and other deterioration occurring during the course of their use. Through the encapsulation of healing material inside microcapsules, which shows rupture upon cracking in cement-based materials, the microcapsule exhibits promise in accomplishing self-healing and increasing durability and strength in the structures. The article first explains the basic ideas behind the science of microcapsule self-healing and then looks at different ways to prepare microcapsules. It also looks into how adding microcapsules affects the basic characteristics of the concrete building. A summary of the efficiency and self-healing mechanisms of microcapsules is also provided. Highlights: The article explains the advantages of the microcapsule self-healing method in concrete. Preparation method and intrinsic properties of different microcapsules are discussed. Different self-healing measurement techniques in cement-based materials are discussed. The study examines the qualitative aspects of various self-healing methods. Looks into how adding microcapsules affects the properties of cementitious materials. [ABSTRACT FROM AUTHOR]

The present study investigated the synergistic influence of bottom ash as a Portland cement (PC) and natural fine aggregate (NFA) replacement in concrete. Coal bottom ash (CBA) is a heavy ash that settles at the bottom of the combustion chamber of a thermal power plant. It was ground (GCBA) for two hours prior to replacing 10–30% PC, while CBA was used in raw form to replace 25% and 50% NFA. The mechanical properties along with durability properties (accelerated carbonation and chloride penetration) were studied after 28 days and 90 days of curing. Non-destructive tests were also performed to check the quality of CBA-based concrete. Microstructural characterisation was conducted using various techniques, namely X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The concrete with 20% GCBA and 25% CBA (G20C25) reported the best performance in terms of parameters studied owing to the pozzolanic reactivity of GCBA and the filler effect of fine CBA. The microstructural investigations also validated the findings and trends observed in the experimental results. Well-fitted mathematical models were derived and optimisation was carried out using the desirability function approach. Multi-objective optimisation recommended 21.80% GCBA and 24.17% CBA as the optimum amount, resulting in a significant reduction of 19.19% and 18.19% in carbon footprint and eco-cost, respectively, compared to the control mix. [ABSTRACT FROM AUTHOR]

Party system institutionalization (PSI) is regarded as a critical underpinning of democracies, but its role in non‐democratic systems has been understudied. In this paper, we evaluate whether the concept has meaningful and perhaps unique implications for the durability of competitive authoritarian regimes. We argue that a modified version of electoral volatility – the most common measure of PSI in democracies – conveys useful information about PSI in competitive authoritarian contexts by signalling the ability of the ruling party to manage the opposition. To this end, we construct an original data set that disaggregates electoral volatility into ruling party seat change and opposition party seat volatility and further divides opposition party volatility into Type‐A and Type‐B volatility. We find robust results that democratization becomes more likely when decreases in the ruling party's seat share coincide with an increase in opposition party Type‐B volatility. This paper demonstrates that the concept of PSI has utility for understanding regime dynamics in competitive authoritarian contexts. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) have gained great attention as a stationary power generation application due to their high efficiency, fuel flexibility and environmental friendliness. The devices and power age could be revolutionized with the commercialization of these technologies. The SOFC-based stationary power generator is one step closer to commercialization however, it is delayed due to the inherent bottleneck of insufficient long-term durability. The cathode current collecting layer (CCCL) is crucial in stack applications to minimize the contact loss between cell and metallic interconnects. Herein, we report an easy-to-fabricate and highly robust CCCL to boost electrochemical performance and long-term durability of flat tubular (FT) short stack. The tailored structure of the CCCL was employed in the fabrication of the FT short-stack. The G/Ag porous structure exhibited increased porosity of 61.2 %, thereby enhancing the mass transport and improving the overall performance and long-term durability. The four-cell FT stack was manufactured without an interconnect and open air-gas channel. Subsequently, the FT short-stack is tested for performance and long-term durability for elapsed 5000 h at a chronopotentiometry test. The porous layer of graphite/Ag on the cathode layer maintained structural integrity without defects and mechanical failure. Consequently, the stack voltage remains stable throughout operation owing to improved structural stability and uniform temperature distribution across four FT cell stack. [Display omitted] [ABSTRACT FROM AUTHOR]

Concrete is the favored construction material, with more than 7 billion cubic meters manufactured annually. Aggregates constitute the crucial component of its structure and quality, responsible for its exceptional characteristic features. The characteristics of aggregates determine the mechanical durability and radiation performance of concrete. In this investigation, fabricated concrete specimens were generated by replacing sand and aggregate sizes with pyrophyllite in 10%–20%–30%–100% proportions. The study investigated the mechanical properties of concrete specimens using both pressure and ultrasound methods, as well as their durability under freeze–thaw and high-temperature (200°C–1,000°C) conditions. In addition, the microstructure and radiation permeability properties were examined over a 7–28–90-day period. Notably, the use of pyrophyllite sand and aggregate significantly increased the compressive strength of the specimens by 21%–63% when compared to the reference concrete after 7–28–90 days, while also reducing mass loss by up to 4.6% during freeze–thaw cycles. After subjecting the specimens to high temperatures, it was discovered that those with an air-cooling regime achieved a compressive value 45% higher than the reference concrete. Microstructure images revealed the formation of C─ S─ H, CH, and portlandite hydration products over 90 days, supporting the observed compressive strength values. The study also has an effective linear attenuation coefficient (LAC) for radiation-shielding properties. According to some radiation-shielding parameters calculated through LAC values, it was revealed that these concrete samples were suitable shielding materials. Pyrophyllite-reinforced specimens have demonstrated potential for high-strength concrete production, suitability for use in high-temperature environments, and effectiveness as shielding in areas with radiation sources. [ABSTRACT FROM AUTHOR]

Thermal energy storage (TES) systems have been proven in their capacity as a crucial component of energy grids relying on renewable sources. An established sensible heat storage technology is a packed-bed TES, employing a granular filling material as a heat storage medium, which is subjected to repeated heating-cooling cycles. As a result of the recurring particle expansion and contraction, excessive stresses and strains can develop and cause material damage. This leads to the increasing need for reliable numerical tools in order to improve the TES design and increase their durability. For this purpose, we propose a continuous thermo-mechanical approach, within the framework of the theory of hypoplasticity, that can accurately predict the single as well as cyclic loading behavior of the filling material. This work focuses on the stress–strain relations and compaction mechanisms of the granular bed in contact with a storage wall with variable inclination and friction coefficient. Furthermore, the important aspect of the wall expansion under the temperature change is also taken into account as well as the specific case when the wall expands more than the granular material. By conducting comprehensive simulations, we demonstrate that our novel numerical model adheres to existing experimental investigations and mitigates shortcomings in the predictive capabilities of previous continuous approaches. [ABSTRACT FROM AUTHOR]

[Display omitted] The electrocatalytic oxygen reduction reaction (ORR) is crucial for energy conversion systems such as fuel cells and metal-air batteries. Boron carbon nitrogen (BCN) is a novel functional material with a high specific surface area, excellent corrosion resistance, and outstanding electrochemical stability. These properties make BCN an effective ORR catalyst and a promising support for metal catalysts. This study leveraged the strong interaction between BCN and metals to anchor platinum nanoparticles (Pt NPs) onto the BCN surface (Pt/BCN), significantly enhancing the durability of traditional Pt/C catalysts in ORR. The half-wave potential of Pt/BCN is 0.927 V, higher than Pt/XC-72R (0.857 V) and commercial Pt/C (0.879 V). Notably, after 10,000 durability test cycles, the mass activity (MA) of Pt/XC-72R and commercial Pt/C decreased by 67 % and 75 %, respectively. Even after 50,000 cycles, Pt/BCN exhibited only a 54 % decrease in MA. Experimental data and density functional theory calculations confirmed increased electron transfer from Pt to the BCN support, indicating a strong electronic metal-support interaction (EMSI) between Pt and BCN. This strong EMSI effectively anchored the Pt NPs, preventing migration and aggregation during the ORR process. Consequently, our research introduces a novel electrocatalyst support material with significant potential for ORR and broader applications. [ABSTRACT FROM AUTHOR]

[Display omitted] Ultralight graphene aerogels have gained extensive recognition in the impact protection field. However, attaining both elasticity and durability at low material density is challenging due to their intrinsic conflicts. Inspired by the mantis ootheca, we present a simultaneous improvement in the elasticity, durability, and density restrictions of ultralight graphene aerogels via constructing a multiscale honeycomb microstructure (MHM) within the graphene skeleton. This approach enables resulting graphene aerogel to achieve a strength per unit volume of 284.6 cm3 mg−1, the ability to recover its shape within 10 ms after an impact at 3.569 m/s, and maintain 97.2 % of its sample height after 20,000 cycles at 90 % strain. The operand analyses and calculation results reveal that the MHM structure facilitates this aerogel's dual-stage stress transfer pathway. Initially, the macroscale honeycomb structure (millimeter-scale) of the graphene aerogels bear and transmit stress to the surrounding regions, followed by the microscale honeycomb structure (micron-scale) deformation to convert stress kinetic energy into elastic potential energy. This two-stage stress transition mechanism of the MHM structure can effectively mitigate excessive local stress and suppress strain localization, thus providing remarkable elasticity and durability. Ultimately, the obtained graphene aerogel demonstrates promising applications as a fall height detection device and impact protective material. [ABSTRACT FROM AUTHOR]

This study aims to investigate the behavior of consumers in rural mountain tourism, with a particular focus on sustainability and durability. Questionnaire surveys were conducted in 2022 in Bucharest during the national tourism fair, collecting responses from 212 visitors based on their availability to participate. Our purpose was to gather their opinions on visiting the rural areas of the Carpathian Mountains in Romania and to reveal distinct patterns in tourist preferences. The responses were analyzed using the Statistical Package for the Social Sciences (SPSS) 20.0, where descriptive analyses and the Mann–Whitney U test were performed. The study results indicated that perceptions and service satisfaction vary based on demographic and economic characteristics. Women slightly favored higher-quality accommodations and dining services, while lower-income and secondary-educated respondents expressed higher contentment with local hospitality. This research emphasizes the need for a nuanced approach to tourism services that promotes local community engagement and sustainable practices to ensure long-term environmental and economic viability. There is a clear need to develop tourism strategies that align with sustainability principles, ensuring that the Carpathian Mountains region remains attractive and resilient for future generations. [ABSTRACT FROM AUTHOR]

In today's era of rapid infrastructure development, ensuring the durability and environmental sustainability of soil subgrades in road construction remains a critical concern. With recent advancements in non-traditional soil stabilizing binders, including environmentally friendly industrial waste materials such as fly ash and slag, there is growing recognition of the potential for limestone powder (LSP), a low-carbon alternative soil stabilizing material, to replace traditional calcium-based additives like ordinary Portland cement (OPC) and lime. However, the full extent of LSP's efficacy in soil treatment has yet to be fully explored. Therefore, this paper investigates the partial substitution of cement with LSP for stabilizing sulfate-bearing saline sandy soil and assesses its impact on the treated soil samples' mechanical properties and durability parameters. For this purpose, five stabilized mixes, including a control mix (no stabilizer), were designed, wherein LSP partially replaced 8% of the OPC at 25%, 50%, and 75% substitution levels. A series of laboratory tests were conducted to track the changes in the geochemical properties and the mineralogical compositions and evaluate the stabilized soil samples' improved mechanical performance and durability parameters. The experimental results show that adding LSP to the cement-treated sulfate-bearing saline soil improved the soil's mechanical properties and enhanced the soil's durability parameters. Specifically, it decreased the soil plasticity, improved the soil strength parameters, enhanced the soil stability, and reduced the volumetric swelling and soil moisture susceptibility. In addition to its technical advantages, using LSP, an industrial byproduct, in soil stabilization offers environmental and economic benefits, highlighting its potential as a sustainable solution in engineering practices. [ABSTRACT FROM AUTHOR]

Persistent memory (pmem) products bring the persistence domain up to the memory level. Intel recently introduced the eADR feature that guarantees to flush data buffered in CPU cache to pmem on a power outage, thereby making the CPU cache a transient persistence domain. Researchers have explored how to enable the atomic durability for applications' in-pmem data. In this article, we exploit the eADR-supported CPU cache to do so. A modified cache line, until written back to pmem, is a natural redo log copy of the in-pmem data. However, a write-back due to cache replacement or eADR on a crash overwrites the original copy. We accordingly developed Hercules, a hardware logging design for the transaction-level atomic durability, with supportive components installed in CPU cache, memory controller (MC), and pmem. When a transaction commits, Hercules commits on-chip its data staying in cache lines. For cache lines evicted before the commit, Hercules asks the MC to redirect and persist them into in-pmem log entries and commits them off-chip upon committing the transaction. Hercules lazily conducts pmem writes only for cache replacements at runtime. On a crash, Hercules saves metadata and data for active transactions into pmem for recovery. Experiments show that, by using CPU cache for both buffering and logging, Hercules yields much higher throughput and incurs significantly fewer pmem writes than state-of-the-art designs. [ABSTRACT FROM AUTHOR]

In this study, the bulk modification method via incorporating two different types of waterproof admixtures was adopted to make natural hydraulic lime-based mortars more durable. The influence of two admixtures and their dosages on the hydration, physical, mechanical, and aggressive environment resistance properties were evaluated. The correlations between pore and water absorption characteristics, between hydration, pore characteristics, and mechanical strength were interpreted. Results showed that two waterproof admixtures changed the microscopic reaction between different components as well as internal structure of NHL-based mortar. Introduction of silane impregnant improved the workability of natural hydraulic lime-based mortars, and the appropriate dosage of silane impregnant facilitated hydration and improved mechanical strength at 28 and 90 days. Silane impregnant modified mortars were no more hydrophilic, acid resistance was improved while water absorption characteristics were not obviously improved even resulting in degraded freeze-thaw cycle resistance. Introduction of silicon-acrylic latex deteriorated the workability and retarded hydration of natural hydraulic lime-based mortars, regardless of dosage, leading to the degradation of mechanical strength. However, water absorption characteristics and freeze-thaw cycle and acid resistance can get a noticeable improvement when appropriate dosage was adopted. [ABSTRACT FROM AUTHOR]

Small ruminants play a significant role in Mauritanian culture and traditions. The purpose of this study was to characterize the breeding system of two locally dominant breeds, the Sahelian goat and the Ladem sheep. This characterization was based on the technical and socio-economic characteristics of the breeders, as well as the morpho-biometric features of the animals. The study was conducted between April and June 2019 and involved 45 breeders located around two small ruminant pilot farms in the Benichab and Kankoussa departments of Mauritania. A questionnaire was administered to the breeders and sixteen measurements were taken on 303 animals (185 goats and 118 sheep). Small ruminant breeding in the study sites is practiced by both men (55%) and women (45%). Breeding can be focused solely on goats (38%), solely on sheep (9%), or include both species (53%). The average herd size is 20 ± 15 for goats and 19 ± 16 for sheep. For the Sahel goat, the height at the wither ranges from 68 to 78 cm in males and from 63 to 76 cm in females, while the body weight ranges from 20 to 43 kg. The most common morphotypes are multicolored (71%), with unicolored animals being less common (29%). As for the Ladem sheep (also known as Touabire), the height at the wither ranges from 70 to 87 cm in males and from 64 to 85 cm in females. The body weight ranges from 25 to 62 kg. The coat is predominantly white with black spots (91%), sometimes red or grey-spotted. The survey also identified the breeding objectives of the farmers. The breeders primarily reported objectives of conformation and growth performances (68%), followed by dual-purpose milk/meat production traits (32%) for the Ladem sheep. In the case of the Sahelian goat, milk production (73%) is the predominant objective, followed by dual-purpose milk/meat production traits (27%). Based on the collected information, tailored selection schemes have been proposed for the Ladem sheep and the Sahelian goat to improve their performances, enhance their breeding, and maintain a focus on the sustainability and resilience of these two local breeds in Mauritania. [ABSTRACT FROM AUTHOR]

The cookstove requires various materials for different stove components, such as the combustion chamber, stove body, insulation, and other accessories, which have a significant impact on the overall combustion performance of the stove. In the present study, two hybrid draft biomass cookstove (HDBC) models with different combustion chamber materials (stainless steel and ceramic refractory cement) were developed and tested. Both stoves in combination with three different insulation materials (perlite, vermiculite, and ceramic wool) were tested using the modified Water Boiling Test (WBT-4.2.3) and Durability Test protocol to assess emissions, efficiency, and stove durability performance. According to the ISO 19867-3:2018 voluntary performance targets, both stainless steel and ceramic combustion chamber stoves with all three insulations met the targets of Tier 5, Tier 4, Tier 3 & 2 and Tier 5 in CO emission, PM2.5 emission, efficiency, and durability performance, respectively. Although there was no significant difference in CO emission, efficiency, modified combustion efficiency (MCE) and durability performance between the two stoves, the ceramic combustion chamber stove emits more PM2.5 than the stainless-steel combustion chamber stove. The combination of stainless-steel combustion chamber and perlite insulation performs overall better than the other combinations. [ABSTRACT FROM AUTHOR]

The effect of direct fire on flexural behavior of small-scale fiber reinforced concrete beams under sustained loading has been studies through an experimental investigation. A mix of synthetic polypropylene structural macro and micro fibers has been used to obtain the effect of mixed fiber dosage on bearing capacity of simply supported beam under direct flame at its bottom face. The load-deflection, temperature gradient, spalling and durability time until collapse has been recorded and compared in different conditions. In order to know the effect of load level, the tests have been performed for 40% and 70% of the ultimate member capacity at normal temperature. Based on obtained test results, the use of macro synthetic fibers can increase the flexural ductility more than 50% and the durability time until failure up to 27%. The post fire behavior curves of all samples at the cooling phase have also been checked until the beam failure has been occurred including the weight losses due to spalling for both heating and cooling phases. A comparison with the results of conventional post fire loading tests on cooled samples showed that the results can be underestimated about 1.5 times compared to the direct fire test. It has also been shown that the level of sustained load directly affects the capacity, durability and ductility while the increase in the number of fibers do not necessarily improve the behavior in the same manner. [ABSTRACT FROM AUTHOR]

Bottom ash needs a pre-treatment process to produce the finer particles until it is like cement material and has a good reactivity as pozzolanic material. This research investigates the effect of using bottom ash on the durability performance of concrete. The modified process was applied to bottom ash to produce finer particles that can improve the durability performances of concrete. The concrete used in this study is self-compacting concrete (SCC) due to its convenience. The bottom ash was pretreated by mechanical grinding before being used as supplementary cement materials (SCM), later called ground bottom ash, and applied from 10% to 50% as the partial replacement by the weight of cement. BA30 showed the highest compressive strength with an increasing percentage of 32% and had a similar value to BA0. The porosity of all mixtures was under 15%. The water absorption of all mixtures was under 10%. BA10, BA20, and BA30 reduced the permeability of the SCC, while BA50 increased the permeability of the SCC. BA30 had the lowest value of RCPT as 916.22 C. The results show that bottom ash positively affects the durability performance of SCC and can be used as an SCM to produce more sustainable cement-based construction materials. [ABSTRACT FROM AUTHOR]

The article presents the course and results of research aimed at assessing the strength and practical usability of a furniture hinge additively manufactured from thermoplastic material. The research activities included: development of design assumptions, adoption of target geometry, creation of a 3D-CAD model, preliminary strength analysis in the FEM environment, prototype manufacturing using FFF method with thermoplastic material (pet-g), and conducting tests under conditions similar to real ones. The hinge geometry was based on typical market-available design solutions, while considering the specifics of the adopted manufacturing method. Strength analysis via FEM was conducted on the 3D-CAD model, allowing estimation of stress values and determination of the suitability of the developed geometry for testing on a real model. Subsequently, research models were produced using FFF technology with various infill patterns: linear 30%, hexagonal 30%, linear 60%, hexagonal 60%, and solid 100%. Bench tests were conducted to determine the maximum load-bearing capacity of the hinge under perpendicular loading to the axis and to assess hinge wear under conditions simulating real-life door usage. The results revealed that the hinge with solid infill safely carried a load of 160 kg without damage, while the hinge with hexagonal 30% infill exhibited the lowest load-bearing capacity, failing at 85 kg. To determine the hinge's durability, the clearance at two reference points on the doors was measured. [ABSTRACT FROM AUTHOR]

Using data on in situ performance of low noise pavements, three well performing mixtures were selected: SDA 4, SDA 6, and SDA 8. These mixtures and the corresponding mastic (filler + bitumen + additive) were tested for their mechanical and acoustic performance in non-aged and aged states using a multi-scale approach (mm to km). Thereafter, an optimization protocol was applied to these mastics (mm-scale) and promising combinations were implemented at the mixture scale (cm-scale). As a result, the best performing mixture parameters were implemented in the m-scale slabs where the mechanical and acoustic performance were determined. The proposed work could uniquely combine knowledge from in situ long term and laboratory performance of low noise pavements. Using a traffic simulator and measurements before and after trafficking, the acoustic modeling showed that the modified mixtures' noise levels were maintained after loading. This indicates that the modification assured acoustical integrity of the mixture after loading. [ABSTRACT FROM AUTHOR]

The outdoor operation of electrochemical solar fuels devices must contend with challenges presented by the cycles of solar irradiance, temperature, and other meteorological factors. Herein, we discuss challenges associated with these fluctuations presented over three timescales, including the effects of diurnal cycling over the course of many days, a single diurnal cycle over the course of hours, and meteorological phenomena that cause fluctuations on the order of seconds to minutes. We also highlight both reaction-independent and reaction-specific effects of variable conditions for the hydrogen evolution reaction and CO2 reduction reaction. We identify key areas of research for advancing the outdoor operation of solar fuels technology and highlight the need for metrics and benchmarks to enable the comparison of diurnal studies across systems and geographical locations. [ABSTRACT FROM AUTHOR]

AbstractThis study comprehensively investigates the literature on using bacteria to confer self-repair abilities on concrete and mortar. Although crack-healing is the main objective, calcite-precipitating bacteria affect concrete’s durability and mechanical properties. This article reviews the research on bacteria-based self-healing concrete and its developments from 1984 to 2023. This systematic review was developed by adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. R studio and Vosviewer were used to perform bibliometric analysis and visualization of the 295 documents by 874 authors affiliated with 97 sources acquired from Scopus (NY). It is vital to emphasise that the document selection was carried out by two impartial reviewers to prevent any bias. In addition to repairing cracks in the material, the data indicate that applying various self-healing bacteria improves concrete’s mechanical and durability properties. A meta-analysis evaluated the summary effect size of the most cited articles. It was concluded with the statistical evidence from the meta-analysis that bacteria incorporated concrete, which shows self-healing efficiency of 5.07 and 7.29 times than that of control concrete. [ABSTRACT FROM AUTHOR]