As luxury fashion brands need to address the environmental impact of their products (both internally and externally), a framework to achieve a common and accessible language becomes paramount to ...avoid confusing claims. Tools, such as Life Cycle Assessment and Eco-Design, help companies assess and reduce the negative effects of their products on the environment; nonetheless, more work is needed. The desire to create durable goods is a direct reaction to the current throw-away culture perpetuated by planned obsolescence during the production phase of many fast-fashion brands. However, without a proper understanding of the term ‘durability’ and its different dimensions, a common language cannot be adopted by the various actors in the value chain (both up- and down-stream). Particularly, the characteristics of terms such as ‘resilience’ are mistakenly confused with those of ‘durability.’ Here, we review the literature from 2011 to date for determining clear definitions for both terms. A self-developed analysis framework was used for the systematic review of the literature, slightly adapting the methodology from an established process. The different levels (A, B, and C) of the framework reveal, in a structured manner, what a ‘durable’ or ‘resilient’ product is (at every stage of its lifecycle). We show that two dimensions should be considered for both concepts: ‘intrinsic’ (also referred to as ‘physical’ in the existing literature) and ‘extrinsic’ (often referred to as ‘emotional’). Most authors fail to acknowledge the existence of both terms or use them inconsistently. Consequently, a thorough assessment of product durability and resilience is lacking, as studies have focused solely on one of the two dimensions or on a single lifecycle stage (most often the design phase) of a product. Thus, beyond its original aim, our model analysis framework can also help evaluate the environmental impact of luxury fashion products at each stage of their lifecycle.
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•The use of an intrinsic and extrinsic dimension is preferred over physical and emotional.•Resilience differs from durability and enables products to bounce back from environmental changes.•All the lifetime stages should be considered to assess a product's durability and resilience.•The analysis framework can serve as a working tool for environmental impact assessment.
Concrete infrastructure repair remains a formidable challenge. We need to understand the repair performance and develop innovative materials and placement processes that lead to durable, ...cost-effective and esthetically pleasing repairs. In this context, fiber reinforced concrete is considered promising.
The influence of fibers on the properties of the interface between old concrete and fiber reinforced repair remains poorly understood. This paper describes an experimental study on the influence of fibers on the mechanical properties of the interface. Bond strength was assessed by means of slant shear tests with different slants. Shear-normal stress interaction diagrams, adhesion strength and internal friction were obtained. Repair mortars with different contents of Polyvinyl Alcohol (PVA) fibers and the influence of wet–dry cycles were investigated.
Results show that PVA fibers added to the repair can significantly enhance interfacial adhesion. Once the repair interface is fully developed, fibers, however, do not mitigate damage from wetting and drying.
The degradation mechanisms of natural fiber in the alkaline and mineral-rich environment of cement matrix are investigated. Cement hydration is presented to be a crucial factor in understanding fiber ...degradation behavior by designing a contrast test to embed sisal fibers in pure and metakaolin modified cement matrices. In addition to durability of sisal fiber-reinforced cement composites determined by means of flexural properties, degradation degree of the embedded fibers is directly evaluated by proposing a novel separation approach. The results indicate that, by reducing alkalinity of pore solution, metakaolin effectively mitigates the deterioration of natural fiber. By combining results of thermogravimetric analysis and microstructure, the alkali degradation process of natural fiber, which consists of hydrolysis of lignin and hemicellulose, stripping of cellulose microfibrils and deterioration of amorphous regions in cellulose chains, is visually presented. Two new concepts of mineralization mechanism, calcium hydroxide (CH)-mineralization and self-mineralization, are also proposed and quantitatively characterized.
Geopolymer (GP) binders are an appealing alternative to Portland cement (PC) binders as they have the potential to reduce the CO2 emissions associated with the cement and concrete industry. However, ...their durability in aggressive environments needs thorough examination if they are to become a viable alternative to traditional PC materials. This study investigated the effect of increasing slag content and activator dosage on the sulfuric acid resistance of fly ash GP binders. Their performance was also compared with that of neat PC mixes using various physical and microstructural techniques. The results show that increasing the slag content of fly ash GPs decreases porosity, but makes the reaction products more susceptible to sulfuric acid attack. It was also found that increasing the alkaline activator dosage of fly ash GPs has little impact on sulfuric acid resistance. Finally, GP binders displayed superior sulfuric acid resistance than their PC counterparts.
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•N- and F-doped bimetallic carbides (C19Cr7Mo24) are synthesized at 1300 °C.•Both show excellent stability and higher ORR activities than Pt/C.•Electron transfer leads to excellent ...activity and stability.•F dopant more favors electron transfer than the N dopant.•Bimetallic carbide more favors electron transfer than monometallic carbide.
Nitrogen- and fluorine-doped bimetallic carbide composites with graphite matrix (abbreviated as C19Cr7Mo24/NG and C19Cr7Mo24/FG) are synthesized through carbonization at 1300 °C. The C19Cr7Mo24/NG displays an initial half-wave potential (E1/2) of 0.873 V and suffers merely 3 mV decrease in E1/2 within 60,000 CV cycles for oxygen reduction reaction (ORR) in alkaline media. A H2/O2 fuel cell testing system using the C19Cr7Mo24/NG as cathode maintains 95.9% of the initial peak power density (1.08 W cm−2) within 60,000 cycles. The C19Cr7Mo24/FG shows higher ORR activity than the C19Cr7Mo24/NG. The positive and negative charge centers caused by the N or F dopants are the critical reasons to their high activities. While F and bimetallic carbide more favor electron transfer respectively than the N and monometallic carbide. Their excellent stabilities originate from interactions among atoms due to electron transfer and the intrinsic chemical inertness of graphite and bimetallic carbides.
Most of the published studies on gear dynamics focused either gear durability or noise and vibration. Dynamic tooth forces and dynamic stress factors were the main concern of the durability related ...work while the dynamic motion transmission error and gearbox vibrations were investigated for noise purposes. Two recent theoretical studies by Tamminana et al. 1 and Velex and Ajmi 2 provided formulations to define certain relationships between the dynamic or quasi-static motion transmission error and dynamic tooth forces or dynamic factor of spur gears in an attempt to bridge these two groups of studies. This paper provides a comprehensive set of experimental data consisting of both dynamic stress factor and dynamic transmission error values collected simultaneously from the same gears to complement these earlier theoretical studies in terms of the relationship between durability and noise metrics. A gear dynamics test set-up with integrated root strain and dynamic transmission error measurement systems is described. Dynamic factor and dynamic transmission error measurements from unmodified and modified spur gears are presented and their relationship is demonstrated experimentally.
•Experimental setup for dynamic stress and transmission error factor measurements.•Simultaneous measurements of DF and DTE were conducted.•Effect of backlash nonlinearity on DF and DTE is demonstrated experimentally.•Impact of tooth modification on DF and DTE is investigated through measurements.•Empirical linear correlation between DF and DTE is given.
The diverse properties reported for starch-based materials indicate their potential for use in the preparation of biodegradable flexible actuators. However, their natural brittleness and lack of ...durability after modification limit their practical application. Therefore, we propose a strategy for preparing flexible starch-based composites. The results of macro/micro property characterizations and molecular dynamics simulations indicated that using starch, maleic anhydride, and stearic acid (SA), the mobility of the starch chains was enhanced and retrogradation was inhibited through the synergistic effects induced by chain breaking, complex formation with SA, and esterification of the starch molecules. In addition, the elongation at break of the modified starch (MS) reached 2070 %, and considerable ductility (>1000 %) as well as well-complexed structure were maintained after six months. Furthermore, the MS was able to undergo self-healing after fracture or a temperature-controlled stiffness transition. Moreover, it underwent complete degradation in soil within 30 d. Finally, an actuator was prepared by doping the MS with nano-Fe3O4 particles to realize a dual magnetic and optical response. Dynamic monitoring was also achieved based on the electrical signal, thereby demonstrating the broad application scope of this material in the development of biodegradable flexible actuators.
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•A test to measure the size and spacing of air voids in fresh concrete is presented.•The test results correlate with both the Spacing Factor and freeze-thaw durability.•The variance of the test is ...similar to the Spacing Factor and freeze-thaw durability.•The test can be completed in the field with simple equipment in less than 10min.
A new approach is presented to determine the air void size and spacing in fresh air entrained concrete by measuring the change in response of the concrete to a series of sequential pressures. This information is used to calculate a parameter called the Sequential Air Method (SAM) Number. Comparisons are made to hardened air void analysis (ASTM C457) from laboratory and field tests for 303 mixtures as well as rapid freeze-thaw testing (ASTM C666) for 68 mixtures to the SAM Number with over 85% agreement. Furthermore, the SAM Number showed a higher correlation to rapid freeze-thaw testing than current recommendations for the Spacing Factor. The variability of the SAM Number is compared to other direct and indirect measurements of air void size and spacing. Finally, several applications of the method are discussed along with guidance on how to specify the method.
Reversible Hydrogen Electrodes
In article number 2309749, Brian A. Rosen and co‐workers show for the first time how atomic substitutions in the MXene can enable its stability under oxidizing ...electrochemical conditions. The cover image is therefore two MXene sheets set up ly as a fuel cell, where the substituted MXene (with the yellow atoms) is exposed to the oxygen electrode and the conventional MXene is exposed to the hydrogen electrode.
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