1D thermo-fluid dynamic modelling of an S.I. single-cylinder H2 engine with cryogenic port injection

This paper describes the numerical and experimental research work carried out on a single-cylinder spark-ignition research engine with cryogenic port injection of gaseous hydrogen. A 1D thermo-fluid dynamic simulation code for the simulation of a hydrogen fuelled S.I. engine has been developed; in particular, a quasi-D multi-zone combustion model has been enhanced to predict the burning rate of a homogeneous mixture of hydrogen and air, on the basis of an extended database for laminar burning velocities. Moreover, a 1D simulation of the unsteady flows in the whole intake and exhaust systems coupled to the engine has been addressed, considering the transport of chemical species to account for the port injection of hydrogen at very low temperature (cryogenic conditions). The working fluid is treated as a mixture of ideal gases, including para-hydrogen, with specific heats depending on the gas temperature and the mole fractions. A validation of the simulation model is shown in the paper, comparing the computed results with the experimental data of in-cylinder pressures, cylinder NO emissions and intake and exhaust instantaneous pressure pulses at different locations, for naturally aspirated engine conditions.     

Change in energy performance as a result of a R422D retrofit: An experimental analysis for a vapor compression refrigeration plant for a walk-in cooler

In this paper, the energy performance of a walk-in cooler working with R22 and its substitute R422D are experimentally studied. The experimental investigation was carried out considering three different operating conditions; in particular, the AHRI standard has been used as reference for operating conditions. All tests were run at steady state conditions and keeping the external air temperature at 35 °C. The experimental analysis allowed the determination of cooling capacity, the electrical power absorbed, the COP and other variables characterizing the working of the plant. The results demonstrated that the cooling capacity for R422D was lower than for R22, while the electrical power absorbed with R422D was higher than that with R22. As consequence, the COP of R422D was lower than that of R22. Furthermore, technical proposals are introduced with the aim of improving the overall performances of those plants, which could be retrofitted with R422D.     

Towards interoperability of i* models using iStarML

Goal-oriented and agent-oriented modelling provides an effective approach to the understanding of distributed information systems that need to operate in open, heterogeneous and evolving environments. Frameworks, firstly introduced more than ten years ago, have been extended along language variants, analysis methods and CASE tools, posing language semantics and tool interoperability issues. Among them, the i* framework is one the most widespread. We focus on i*-based modelling languages and tools and on the problem of supporting model exchange between them. In this paper, we introduce the i* interoperability problem and derive an XML interchange format, called iStarML, as a practical solution to this problem. We first discuss the main requirements for its definition, then we characterise the core concepts of i* and we detail the tags and options of the interchange format. We complete the presentation of iStarML showing some possible applications. Finally, a survey on the i* community perception about iStarML is included for assessment purposes.     

DNA damage, severe organ lesions and high muscle levels of As and Hg in two benthic fish species from a chemical warfare agent dumping site in the Mediterranean Sea

The aim of the present study was to evaluate the environmental threat to benthic species from chemical weapons dumped in the southern Adriatic Sea. An ecotoxicological approach using chemical analysis and biological responses was applied, in two sentinel species: the Blackbelly rosefish Helicolenus dactylopterus and European conger Conger conger. Specimen were collected in a stretch of sea, where had been dumped war materials and from a reference site free of ordnance. Residues of yperite, Hg and As were measured in fish fillets. Skin, liver, kidney and spleen were examined for histopathological and macroscopical lesions. Liver detoxifying capacities (EROD and UDPGT) and genotoxicity (comet assay) were also investigated. As and Hg levels were three-four times higher than those from the reference site in both species (p < 0.001). Both species captured in dumping site showed clear signs of chronic illness according to the health assessment index (HAI). Deep ulcers and nodules were observed on skin and external organs. Histological lesions such as periportal and bile duct fibrosis, pericholangitis, steatosis, granuloma and elevated splenic MMCs were detected in liver and spleen. Significantly higher EROD activities were also found in both species from dumping site (p < 0.01). Comet assay revealed genotoxicty in gills of C. conger from dumping site, indicating uptake of chemical warfare agents through fish gills. European conger was found to be a more sensitive bioindicator of this type of contamination than the Blackbelly rosefish.     

Molecular and Supramolecular Structural Studies on Significant Repetitive Sequences of Resilin

Resilin is a member of the family of elastomeric proteins and is found in specialised regions of the cuticle of most insects, and provides low stiffness, high strain and efficient energy storage. It is best known for its role in insect flight and the remarkable jumping ability of fleas and spittle bugs. In common with other elastomeric proteins, the recently identified Drosophila melanogaster proresilin shows glycine‐rich repetitive sequences; in particular the N‐ and C‐terminal regions of the protein are dominated by 18 repeats of a 15‐residue sequence (SDTYGAPGGGNGGRP) and eleven repeats of a 13‐residue sequence (GYSGGRPGGQDLG), respectively. We synthesised and analysed the molecular and supramolecular structure of some polypeptides with sequences belonging to the glycine‐rich repeated domain of D. melanogaster resilin. The conformational studies performed by CD, FTIR and NMR spectroscopies pointed to the coexistence of two main conformational features, such as folded β‐turns and (quasi)extended structures (e.g., poly‐L ‐proline II conformation) in common with other elastomeric proteins; this suggests an elasticity mechanism for resilin common to other elastomeric proteins. Our data show that also in the case of resilin, repetitive sequences are characterised by autonomous structures almost independent of the remaining parts of the molecule as already extensively found for elastin. From a supramolecular point of view, a great tendency to aggregate in fibrous structures is observed, particularly for the resilin‐ inspired polypeptide (PGGGN)₁₀. This is encouraging for the development of resilin‐based biomaterials for the production of biocompatible medical devices, as well as high performing elastic materials.     

Residual effects of lead and zinc mining on freshwater mussels in the Spring River Basin (Kansas, Missouri, and Oklahoma, USA)

Concentrations of selected trace elements in surface water and fluvial sediment were investigated as possible factors limiting the distribution and abundance of freshwater mussels in the Spring River Basin, a 6600 km(2) watershed overlapping a former Pb and Zn mining and ore processing district in the central USA. Mussel taxa richness surveys and supporting physical habitat assessments were performed in 23 stream reaches dispersed throughout the basin and above and below former mining sites. Quantitative mussel density surveys were performed in the Spring River at one upstream reference location and one downstream location. Concentrations of 16 trace elements in the soft tissues of mussels and Asian clams (Corbicula fluminea) were determined at most survey sites. Comparable analyses were performed on surface water samples collected during base flow and peak flow synoptic surveys and sediment samples collected during base flow periods. Sites on the Spring River immediately upstream of heavily mined areas supported at least 21-25 species of mussels, whereas sites near the lower terminus of the river yielded evidence of 6-8 extant species. Between the upper and lower quantitative survey sites, mean mussel and clam densities declined by 89% and 97%, respectively. Tributary reaches below heavily mined areas lacked evident bivalve communities and contained concentrations of Cd, Pb, and Zn that continually or sporadically exceeded hardness-dependent water quality criteria and consensus-based sediment quality guidelines (probable effect concentrations). In less contaminated stream reaches supporting bivalves, concentrations of Cd, Pb, and Zn in mussels and clams were correlated spatially with the levels occurring in surficial sediment (0.50 < or = tau < or = 0.64, p < or = 0.03). In non-headwater perennial stream reaches, sediment Cd, Pb, and Zn levels were related inversely to mussel taxa richness (-0.80 < or = tau < or = -0.64, p < or = 0.004). Metal contaminant burdens in mussels and clams fluctuated measurably in association with variable stream flow conditions and accompanying changes in surface water and sediment chemistry. Concentrations of Cd, Pb, and Zn in mussels approximately paralleled the levels measured in composite clam samples (0.74 < or = tau < or = 0.79, p<0.001), implying C. fluminea could serve as a possible surrogate for native mussels in future metal bioaccumulation studies. Overall, streams draining heavily mined areas exhibited depauperate (or fully extirpated) mussel assemblages and correspondingly elevated concentrations of Cd, Pb, and Zn in water, sediment, and bivalve tissue. Other evaluated environmental chemistry parameters, and physical habitat conditions assessed at the stream reach scale, demonstrated little general relationship to the degraded status of these assemblages. We conclude that pollution attributable to former mining operations continues to adversely influence environmental quality and impede the recovery of mussel communities in a large portion of the Spring River Basin.     

Low‐Power‐Photon Up‐Conversion in Dual‐Dye‐Loaded Polymer Nanoparticles

Sensitized triplet–triplet annihilation in multicomponent organic systems is already demonstrated to be suitable for obtaining efficient up‐conversion in solution with excitation power densities comparable to solar irradiance, but loses efficiency in the solid state. Here, it is demonstrated that it is possible to reduce this limitation by incorporating a standard bicomponent system in polymer nanoparticles. The confinement of all of the involved photophysical processes in a nanometer‐scale volume makes each nanoparticle a single and isolated high‐efficiency up‐converting unit. As a consequence, these dual‐dye‐loaded nanoparticles can be used to produce drop‐cast films, as well as dopants for polymeric matrices, preserving the performances of the starting moieties in solution.     

Photodegradation of fluoroquinolones in surface water and antimicrobial activity of the photoproducts

The widespread presence of fluoroquinolone antibiotics (FQs) in natural ecosystems is a health hazard for humans and other living organisms. The role of sunlight in degrading FQs present in environmental waters has been studied. In particular, the photodegradation of four largely employed FQs, viz. Ciprofloxacin (CIP), Danofloxacin (DAN), Levofloxacin (LEV) and Moxifloxacin (MOX) has been studied in not tampered river water. Degradation rates have been investigated at ppb levels (20-50 μg L⁻¹) under solar light, and the results have been commented critically. The products distribution has been studied by HPLC-ESI-MS/MS analysis and structures have been attributed on the basis of their mass fragmentation spectra.Importantly from the environmental point of view, the (potentially toxic) FQ nucleus remained intact over the early stages of the degradation. Indeed, the photoproducts were proved to possess residual antibacterial activity, as shown from in vitro antibacterial activity tests against different well characterized human and environmental bacterial strains, carried out on the above FQs, as well as for Enrofloxacin (ENR) and Marbofloxacin (MAR).     

Using land to mitigate climate change: hitting the target, recognizing the trade-offs

Land can be used in several ways to mitigate climate change, but especially under changing environmental conditions there may be implications for food prices. Using an integrated global system model, we explore the roles that these land-use options can play in a global mitigation strategy to stabilize Earth's average temperature within 2 °C of the preindustrial level and their impacts on agriculture. We show that an ambitious global Energy-Only climate policy that includes biofuels would likely not achieve the 2 °C target. A thought-experiment where the world ideally prices land carbon fluxes combined with biofuels (Energy+Land policy) gets the world much closer. Land could become a large net carbon sink of about 178 Pg C over the 21st century with price incentives in the Energy+Land scenario. With land carbon pricing but without biofuels (a No-Biofuel scenario) the carbon sink is nearly identical to the case with biofuels, but emissions from energy are somewhat higher, thereby results in more warming. Absent such incentives, land is either a much smaller net carbon sink (+37 Pg C - Energy-Only policy) or a net source (-21 Pg C - No-Policy). The significant trade-off with this integrated land-use approach is that prices for agricultural products rise substantially because of mitigation costs borne by the sector and higher land prices. Share of income spent on food for wealthier regions continues to fall, but for the poorest regions, higher food prices lead to a rising share of income spent on food.