While the “useful life” of products plays an important role in the balance of sustainability and lifecycle assessment, the concept of durability, as the main measure of useful life, is still ill-defined. This paper critically considers the limitations of the current definitions and approaches to durability, by reflecting on the complex interactions of the viewpoints of engineering design teams, users, society and business economics. A new definition is proposed for durability relating to the useful life goals for a product within its techno-socio-economic context.

Selection of microscopes for student use involves many factors. The microscopes must stand up to daily use by students with little experience, be constantly up and running, and fit the budget requirements. Especially with student microscopes, practical aspects can be important. Thus, size, weight, cabling, and design should be taken into consideration even before the microscope and its accessories enter the decision process. If chosen carefully, educational microscopes can delight young minds in schools and universities, and, ideally, the experience will fascinate them enough that they decide to make science their profession.

Empirical studies find that expenditures on both durable and nondurable goods fall following a contractionary monetary policy shock. However, in standard two-sector models with staggered nondurable goods prices and flexible durable goods prices, consumption of durables rises whereas that of nondurables falls in response to a contractionary policy shock. To resolve this co-movement problem, I extend the model to include a realistic financial friction that firms must pay for their productive inputs prior to production, i.e., working capital, along with habit formation in nondurable goods consumption. Following a positive interest rate shock, the working capital channel raises production costs, thereby discouraging production of both durable and nondurable goods. Furthermore, habit formation induces households to smooth the growth rate of nondurable goods consumption, and hence mitigates the fall in the nondurable goods sector. The model solves the co-movement problem and successfully generates a more sensitive response in the durable goods sector, as observed in the data.

For microorganisms, the preferred living state is adhering to surfaces that can lead tothe development of a biofilm. In drinking water networks, a biofilm can affect theorganoleptic quality of the water as well as whether it is safe to drink. This is due tothe probable presence of pathogens inside the biofilm which may be spread in the water. Tokeep the water quality safe, sanitization processes are regularly carried out usingoxidizing biocides which can alter the physico-chemical properties of the material. Due totheir surface physico-chemical properties and their high corrosion resistance, stainlesssteels seem to be good candidates for the making of drinking water systems. In this 2 yearstudy, stainless steel grades were compared with materials commonly used, in respect offouling, biofilm development and composition. The tested stainless steels include ferritic(444/EN 1.4521), three austenitic (304L/EN 1.4307, 316L/EN 1.4404, and 316LN/EN 1.4429)and two duplex (2304 /EN 1.4362, and 2205/EN 1.4462) grades. The experiments wereperformed in a pilot specially designed to assess the material biocontamination on anatural drinking water loop for more than 2 years. The results confirmed the significantimpact of the material on the biofilm development in terms of formation kinetic andecology. No differences were observed between stainless steel grades whereas theydisplayed an intermediate behaviour compared to other materials. Corrosion attacks wereonly observed on galvanised carbon steel while on stainless steels, negligible releaserates, much below international health requirements were measured. So stainless steelsoffer a good compromise to make drinking water pipes.

Recent studies have provided evolutionary explanations for much of the variation in mortality among human infectious diseases. One gap in this knowledge concerns respiratory tract pathogens transmitted from person to person by direct contact or through environmental contamination. The sit-and-wait hypothesis predicts that virulence should be positively correlated with durability in the external environment because high durability reduces the dependence of transmission on host mobility. Reviewing the epidemiological and medical literature, we confirm this prediction for respiratory tract pathogens of humans. Our results clearly distinguish a high-virulence high-survival group of variola (smallpox) virus, Mycobacterium tuberculosis, Corynebacterium diphtheriae, Bordetella pertussis, Streptococcus pneumoniae, and influenza virus (where all pathogens have a mean percent mortality [ges ]0.01% and mean survival time >10 days) from a low-virulence low-survival group containing ten other pathogens. The correlation between virulence and durability explains three to four times of magnitude of difference in mean percent mortality and mean survival time, using both across-species and phylogenetically controlled analyses. Our findings bear on several areas of active research and public health policy: (1) many pathogens used in the biological control of insects are potential sit-and-wait pathogens as they combine three attributes that are advantageous for pest control: high virulence, long durability after application, and host specificity; (2) emerging pathogens such as the ‘hospital superbug’ methicillin-resistant Staphylococcus aureus (MRSA) and potential bioweapons pathogens such as smallpox virus and anthrax that are particularly dangerous can be discerned by quantifying their durability; (3) hospital settings and the AIDS pandemic may provide footholds for emerging sit-and-wait pathogens; and (4) studies on food-borne and insect pathogens point to future research considering the potential evolutionary trade-offs and genetic linkages between virulence and durability.

Ultrahigh-performance concretes (UHPCs) are obtained by optimizing several technologies: minimizing the amount of water added, using superplasticizers and a wide particle size distribution, and packing the particles to improve fluidity with minimized water additions and to optimize load-carrying capacity. Fibers can be incorporated to increase ductility, leading to ultrahigh-performance fiber-reinforced concretes (UHPFRCs). Such enhanced concretes can approach the compressive strength of steel, with a remarkable improvement in durability. UHPCs offer new solutions for innovative construction, especially in aggressive environments.