High-performance materials in infrastructure: a review of applied life cycle costing and its drivers – the case of fiber-reinforced composites

IIn recent years, an investment bottleneck for public infrastructure has accumulated in many industrial countries. Life cycle costing (LCC) is an appropriate management instrument for long-term and sustainable investment. This article addresses the evaluation of high-performance materials (HPM) using LCC to reduce that investment bottleneck. Our research questions are, first, whether and how LCC can be applied to HPM, second, which drivers are primarily influencing the results of a LCC analysis for HPM, and finally, whether HPM are suitable for infrastructure investments, according to economic, social and environmental criteria. We use a comprehensive literature review to analyze existing case studies that apply LCC to HPM. Our review shows that LCC is applied to HPM for structural applications with different levels of detail and quality. The initial results indicate that total life cycle costs for HPM are on average 10% higher. We urge the optimization of the cost structure of HPM to achieve the same level of life cycle costs as conventional construction materials. Moreover, we argue for a more holistic approach that does not ignore sustainability criteria throughout the life cycle of HPM based on the identified drivers of life cycle costs: external costs, an extended life cycle, the discount rate and the expected service life. Indeed, a screened subsample of eight cases is very competitive, with average total life cycle costs for HPM that are 8.4% lower. We share the belief in a more eco-centric approach and, therefore, demand further research into a societal type of LCC that improves the mechanical properties while not ignoring sustainability criteria for new product systems such as HPM

Uncertainty in life cycle costing for long-range infrastructure. Part I: leveling the playing field to address uncertainties

Purpose Life cycle costing (LCC) is a state-of-the-art method to analyze investment decisions in infrastructure projects. However, uncertainties inherent in long-term planning question the credibility of LCC results. Previous research has not systematically linked sources and methods to address this uncertainty. Part I of this series develops a framework to collect and categorize different sources of uncertainty and addressing methods. This systematization is a prerequisite to further analyze the suitability of methods and levels the playing field for part II. Methods Past reviews have dealt with selected issues of uncertainty in LCC. However, none has systematically collected uncertainties and linked methods to address them. No comprehensive categorization has been published to date. Part I addresses these two research gaps by conducting a systematic literature review. In a rigorous four-step approach, we first scrutinized major databases. Second, we performed a practical and methodological screening to identify in total 115 relevant publications, mostly case studies. Third, we applied content analysis using MAXQDA. Fourth, we illustrated results and concluded upon the research gaps. Results and discussion We identified 33 sources of uncertainty and 24 addressing methods. Sources of uncertainties were categorized according to (i) its origin, i.e., parameter, model, and scenario uncertainty and (ii) the nature of uncertainty, i.e., aleatoric or epistemic uncertainty. The methods to address uncertainties were classified into deterministic, probabilistic, possibilistic, and other methods. With regard to sources of uncertainties, lack of data and data quality was analyzed most often. Most uncertainties having been discussed were located in the use stage. With regard to methods, sensitivity analyses were applied most widely, while more complex methods such as Bayesian models were used less frequently. Data availability and the individual expertise of LCC practitioner foremost influence the selection of methods. Conclusions This article complements existing research by providing a thorough systematization of uncertainties in LCC. However, an unambiguous categorization of uncertainties is difficult and overlapping occurs. Such a systemizing approach is nevertheless necessary for further analyses and levels the playing field for readers not yet familiar with the topic. Part I concludes the following: First, an investigation about which methods are best suited to address a certain type of uncertainty is still outstanding. Second, an analysis of types of uncertainty that have been insufficiently addressed in previous LCC cases is still missing. Part II will focus on these research gaps

Recognition of double-stranded DNA using energetically activated duplexes with interstrand zippers of 1-, 2-or 4-pyrenyl-functionalized O2 '-alkylated RNA monomers

Despite advances with triplex-forming oligonucleotides, peptide nucleic acids, polyamides and - more recently - engineered proteins, there remains an urgent need for synthetic ligands that enable specific recognition of double-stranded (ds) DNA to accelerate studies aiming at detecting, regulating and modifying genes. Invaders, i.e., energetically activated DNA duplexes with interstrand zipper arrangements of intercalator-functionalized nucleotides, are emerging as an attractive approach toward this goal. Here, we characterize and compare Invaders based on 1-, 2- and 4-pyrenyl-functionalized O2′-alkylated uridine monomers X–Z by means of thermal denaturation experiments, optical spectroscopy, force-field simulations and recognition experiments using DNA hairpins as model targets. We demonstrate that Invaders with +1 interstrand zippers of X or Y monomers efficiently recognize mixed-sequence DNA hairpins with single nucleotide fidelity. Intercalator-mediated unwinding and activation of the double-stranded probe, coupled with extraordinary stabilization of probe-target duplexes (ΔT(m)/modification up to +14.0 °C), provides the driving force for dsDNA recognition. In contrast, Z-modified Invaders show much lower dsDNA recognition efficiency. Thus, even very conservative changes in the chemical makeup of the intercalator-functionalized nucleotides used to activate Invader duplexes, affects dsDNA-recognition efficiency of the probes, which highlights the importance of systematic structure-property studies. The insight from this study will guide future design of Invaders for applications in molecular biology and nucleic acid diagnostics

Green-light photocleavable meso-methyl BODIPY building blocks for macromolecular chemistry

We report the design of easily accessible, photocleavable meso-methyl BODIPY monomers suitably functionalised for incorporation into macromolecules. Firstly a BODIPY-diol as a novel AA-type bifunctional monomer is reported. Secondly, from the same common BODIPY precursor, a clickable, azide functionalised AB-type hetero-bifunctional monomer was prepared. Photochemical studies of model compounds confirmed the ability of these compounds to undergo photocleavage in green light (lambda > 500 nm). Their usefulness for photoclippable macromolecular systems is then demonstrated: firstly by incorporating the diols into polyurethane hydrogels shown to undergo photocleavage and hence dissolution under visible light irradiation and secondly, the preparation of water-soluble macromolecular photocages able to photorelease small molecules. Thus the results presented herein describe a proof-of-principle for BODIPY-based photoresponsive materials, for example, for use as degradable polymers, sacrificial materials for lithography or for the delivery of caged pharmaceuticals

Environmental effects on the covariation among pace-of-life traits

Pace‐of‐life syndromes (POLSs) are suites of life‐history, physiological and behavioural traits that arise due to trade‐offs between allocation to current and future reproduction. Traits generally show covariation that can arise from genetic and environmental influences on phenotypes and constrain the independent evolution of traits, resulting in fitness consequences and impacts on population dynamics. The notion that correlations among traits may vary among populations along environmental gradients suggests an important role for the environment in shaping and maintaining POLSs. However, no synthesis has been attempted of the myriad ways in which environmental factors should influence POLSs. Here, we formulate a series of hypotheses targeting the critical interfaces of the environment and life‐history ‐ behaviour associations across different organisms. We discuss the hypotheses in light of findings from a systematic review of studies that measured changes in the association between behaviour and life‐history traits as a function of environmental conditions. The review revealed that POLSs are often shaped by environmental variation, where harshness of the environment in early life has the most consistent effects on POLS. However, only partial or no effects of environmental variation were found in a number of studies, which may result from the highly variable study systems, traits and environments studied. We highlight promising directions arising from the available studies and identify knowledge gaps that, if unaddressed, will impede progress in the field

Biogenic hydrocarbon emissions from southern African savannas

Biogenic nonmethane hydrocarbon (NMHC) emissions were investigated at two field sites in the Republic of South Africa that include five important southern African savanna landscapes. Tropical savannas are a globally important biome with a high potential for biogenic emissions but no NMHC emission measurements in these regions or in any part of Africa have been reported. Landscape average hydrocarbon emissions were estimated by characterizing plant species composition and foliar density at each site, identifying and characterizing NMHC emissions of the most abundant plant species, and identifying and characterizing NMHC emissions of plant species with the highest NMHC emission rates. A hand-held portable analyzer proved to be a useful tool for identifying plants with high emission rates. A branch enclosure system, with gas chromatography and flame ionization detector, was used to quantify isoprene and monoterpene emission rates. Emission rates were species-specific and several genera had both high and low emitters. At least some species with high emission rates were identified in most savanna types. High and low emitters were found on both nutrient-rich and nutrient-poor soils. Landscape average emission capacities for the five savanna types range from 0.6 to 9 mg C m-2 h-1 for isoprene and about 0.05 to 3 mg C m-2 h-1 for monoterpenes. The savanna emission rates predicted by existing global models are within the range estimated for these five savanna types

Isoflurane vs. propofol for sedation in invasively ventilated patients with acute hypoxemic respiratory failure: an a priori hypothesis substudy of a randomized controlled trial

Background Acute hypoxemic respiratory failure (AHRF) is a leading concern in critically ill patients. Experimental and clinical data suggest that early sedation with volatile anesthestics may improve arterial oxygenation and reduce the plasma and alveolar levels of markers of alveolar epithelial injury and of proinflammatory cytokines. Conclusions In patients with AHRF, inhaled sedation with isoflurane for a duration of up to 48 h did not lead to improved oxygenation in comparison to intravenous sedation with propofol. Trial registration The main study was registered in the European Medicines Agency's EU Clinical Trial register (EudraCT), 2016-004551-67, before including the first patient. The present substudy was registered at German Clinical Trials Register (DRKS, ID: DRKS00018959) on January 7th, 2020, before opening the main study data base and obtaining access to study results

Isoprene fluxes measured by enclosure, relaxed eddy accumulation, surface layer gradient, mixed layer gradient, and mixed layer mass balance techniques

Isoprene fluxes were estimated using eight different measurement techniques at a forested site near Oak Ridge, Tennessee, during July and August 1992. Fluxes from individual leaves and entire branches were estimated with four enclosure systems, including one system that controls leaf temperature and light. Variations in isoprene emission with changes in light, temperature, and canopy depth were investigated with leaf enclosure measurements. Representative emission rates for the dominant vegetation in the region were determined with branch enclosure measurements. Species from six tree genera had negligible isoprene emissions, while significant emissions were observed for Quercus, Liquidambar, and Nyssa species. Abovecanopy isoprene fluxes were estimated with surface layer gradients and relaxed eddy accumulation measurements from a 44-m tower. Midday net emission fluxes from the canopy were typically 3 to 5 mg C m-2 h-1, although net isoprene deposition fluxes of-0.2 to -2 mg C m-2 h-1 were occasionally observed in early morning and late afternoon. Above-canopy CO2 fluxes estimated by eddy correlation using either an open path sensor or a closed path sensor agreed within ±5%. Relaxed eddy accumulation estimates of CO2 fluxes were within 15% of the eddy correlation estimates. Daytime isoprene mixing ratios in the mixed layer were investigated with a tethered balloon sampling system and ranged from 0.2 to 5 ppbv, averaging 0.8 ppbv. The isoprene mixing ratios in the mixed layer above the forested landscape were used to estimate isoprene fluxes of 2 to 8 mg C m-2 h-1 with mixed layer gradient and mixed layer mass balance techniques. Total foliar density and dominant tree species composition for an approximately 8100 km2 region were estimated using high-resolution (30 m) satellite data with classifications supervised by ground measurements. A biogenic isoprene emission model used to compare flux measurements, ranging from leaf scale (10 cm2) to landscape scale (102 km2), indicated agreement to within ±25%, the uncertainty associated with these measurement techniques. Existing biogenic emission models use isoprene emission rate capacities that range from 14.7 to 70 μg C g-1 h-1 (leaf temperature of 30°C and photosynthetically active radiation of 1000 μmol m-2 s-1) for oak foliage. An isoprene emission rate capacity of 100 μg C g-1 h-1 for oaks in this region is more realistic and is recommended, based on these measurements

Air Quality Modeling for the Urban Jackson, Mississippi Region Using a High Resolution WRF/Chem Model

In this study, an attempt was made to simulate the air quality with reference to ozone over the Jackson (Mississippi) region using an online WRF/Chem (Weather Research and Forecasting–Chemistry) model. The WRF/Chem model has the advantages of the integration of the meteorological and chemistry modules with the same computational grid and same physical parameterizations and includes the feedback between the atmospheric chemistry and physical processes. The model was designed to have three nested domains with the inner-most domain covering the study region with a resolution of 1 km. The model was integrated for 48 hours continuously starting from 0000 UTC of 6 June 2006 and the evolution of surface ozone and other precursor pollutants were analyzed. The model simulated atmospheric flow fields and distributions of NO2 and O3 were evaluated for each of the three different time periods. The GIS based spatial distribution maps for ozone, its precursors NO, NO2, CO and HONO and the back trajectories indicate that all the mobile sources in Jackson, Ridgeland and Madison contributing significantly for their formation. The present study demonstrates the applicability of WRF/Chem model to generate quantitative information at high spatial and temporal resolution for the development of decision support systems for air quality regulatory agencies and health administrators