840 research outputs found
Safe production of nitrated intermediates of industrial interest using traditional batch reactors and innovative microdevices
2 and 3- nitrobenzaldehydes are two isomers involved in a wide range of fine chemicals production, from dyes to pesticides. They are also employed in highly priced materials production such as pharmaceuticals, photo-removable protecting groups, and non-linear optical materials. Direct fed-batch nitration of benzaldehyde for their production suffers from different drawbacks such as the difficulties in controlling the two isomers yields at different nitrating agent compositions and the possibility of thermal runaway of the system. Moreover, adopting the traditional processes of production of benzaldehyde, it is impossible to obtain chlorine-free benzaldehyde and high temperatures and pressures are required. In this thesis, the possibility of synthesizing 2 and 3-nitrobenzaldehyde, using both benzyl alcohol and benzaldehyde as a row material, is investigated in concentrated mixtures of nitric and sulfuric acids, i.e. mixed acid. In fact, despite the new interest for innovative and alternative nitrating agents, mixed acid still represents the most used and effective reaction media in nitration processes. The adoption of benzyl alcohol as an alternative organic substrate is attractive since it is a lower priced material obtainable in high purity. In this work a successful attempt of conducting tandem oxidation-nitration reaction in a one step process is shown, highlighting the advantages and the drawbacks of this process and proposing some possible alternative reactor design solutions.
A first investigation was devoted to clarify some aspects concerning nitric acid speciation in concentrated ternary mixture of nitric acid, sulfuric acid and water and the relative influence of the acids concentrations on their dissociation. As a result, different semi-empirical and empirical correlations were proposed to predict nitronium ion concentrations at varying conditions, defining and overcoming the limitations of the conflicting theories proposed in the literature. Moreover, the study of the influence of sulfuric acid on nitric acid dissociation helped in developing more reliable kinetic models.
A kinetic modeling of tandem oxidation-nitration of benzyl alcohol to nitrobenzaldehydes was developed in order to successfully predict the behavior of the reacting system at varying process conditions and clarify the mechanisms of reaction. Specifically, the influence of temperature and composition of the reaction media was clarified. The developed kinetic model elucidated the mechanism of formation of important intermediates such as the coordinated form of nitronium ion with the aldehydic group of benzaldehyde to form ortho-nitrobenzaldehyde.
The intensification of nitrobenzaldehydes synthesis was studied using a commercially available microreactor, which allowed to carry out the process under harsher conditions. As a result, it was possible to produce the two isomers with the highest yields obtained so far.
Finally an extension of the developed model to investigate benzaldehyde nitration kinetics under heterogeneous liquid-liquid conditions was provided
Habitat use by foraging bats (Mammalia: Chiroptera) in southern Italy determined by broad-band acoustic surveys and radiotracking.
Species Distribution Models: exploring patterns and processes in mammal ecology
Modelling species distribution is one of the most widely used approaches used by modern ecologists to predict species occurrence as well as to explore the environmental variables that determine the presence of a species in an habitat. Given the outstanding importance of mammals in the context of conservation or management actions, it is not surprising that an ever increasing number of mammalogists have successfully employed species distribution models over the last few years. As a scientific journal devoted to mammal natural history, Hystrix, the Italian Journal of Mammalogy is pleased to present a collection of articles forming a special issue that deals with such an important and timely matter
Painting maps with bats: Species distribution modelling in bat research and conservation
Species distribution models (SDMs) offer an effective tool for identifying species conservation requirements and forecasting how global environmental changes will affect species diversity and distribution. This approach is particularly relevant for bats because their nocturnal behaviour hinders detectability and identification in flight. Despite their important contribution to global biodiversity and wide geographical ranges, bats have been under-represented in early SDM studies, and only in the last few years has this approach become more widely used in bat research. We carried out a meta-analysis of the published literature to review the history of the use of SDMs in bat research and their application in conservation, climate change assessments and genetic studies. We focus on the geographical coverage, theme and modelling algorithm of published studies, and compare studies that are uniquely dedicated to bats to multi-taxa studies that include bats. We provide recommendations for good modelling practices through considering spatial scale and spatial biases, selecting ecologically relevant variables, following rigorous modelling protocols, and recognising the limitations of extrapolation across temporal scales. We suggest future developments that will further favour the use of SDMs to study bat ecology and biogeography, as well as inform conservation management. We conclude that despite an increase in bat SDM studies, their scope and application can be further enhanced through incorporating dispersal, landscape connectivity and biotic interactions between bats, their prey and their pathogens
Molecular Identification of Italian Mouse-eared Bats (genus Myotis)
Despite the fact that the genus Myotis (Mouse-Eared bats) is
one of the most investigated microchiropteran groups, recent molecular
studies highlighted the presence of several cryptic species with substantial
implications for ecological and conservation issues. Our dataset includes 55
coxI sequences from 11 morphologically-identified Italian Mouse-Eared bats
species. We applied an integrated approach comparing data from a traditional
morphological identification and molecular variability in a fragment of the
mitochondrial coxI gene (DNA barcoding). Our results clearly show a strong
coherence between the two identification approaches for almost all of the
examined species, and revealed interesting patterns of intraspecific variability
within the species M. nattereri. Finally, we successfully tested the efficacy of
our identification method on undetermined individuals sampled in the field
Higher and bigger:How riparian bats react to climate change
Highlights•In 2000–23, Daubenton's bats reacted to climate change along an altitude gradient.•Climate warmed, but habitat quality remained unchanged during this time.•Females shifted their elevational limit upward by 175 m.•Bats grew significantly larger, possibly due to more favourable roost temperatures.•Future risks: Social disruption and higher mortality in larger bats.AbstractThe altitudinal distribution of animals and changes in their body size are effective indicators of climate change. Bats are sensitive to climate change due to their dependence on temperature during critical life stages. However, long-term studies documenting responses over extended periods are rare. We present a 24-year investigation of Myotis daubentonii, a riparian bat known for altitudinal sexual segregation, along a river course in Central Italy. While males occupy the entire river course, females are confined to downstream warmer areas supporting successful reproduction due to improved foraging site productivity. In 2000, females were absent above 900 m a.s.l in our study area. We hypothesise that a) this altitude threshold is now higher, due to thermal gradient changes along the river course; and b) thermoregulatory costs for reproductive females have declined, leading to increased energy investment in offspring and subsequent generational growth in bat body size. Confirming our hypotheses, females exhibited a 175-m upward shift in altitude limit. Furthermore, we found a concurrent increase in body size (but not condition). Temperatures increased in the 24 years, likely allowing females to extend their range to higher elevations and favouring an increase in newborn body mass. Riparian vegetation remained unchanged, excluding habitat quality changes as the cause for the observed responses. The rapid female elevation rise might imply future disruption of established social structures, altering intra- and intersexual competition for roosts and food. Given the global decline in insect populations, larger bats might face future difficulties in finding food to sustain their body size, increasing mortality. However, the full impact of such changes on bat fitness remains unexplored and warrants further investigation, including other bat populations. This knowledge is crucial for informing conservation in the face of ongoing climate change and preserving the ecosystem services bats deliver in riparian ecosystems
Bats and Water: Anthropogenic Alterations Threaten Global Bat Populations
Natural bodies of open water in desert landscapes, such as springs and ephemeral pools, and the plant-life they support, are important resources for the survival of animals in hyper arid, arid and semi-arid (dryland) environments. Human-made artificial water sources, i.e. waste-water treatment ponds, catchments and reservoirs, have become equally important for wildlife in those areas. Bodies of open water are used by bats either for drinking and/or as sites over which to forage for aquatic emergent insects. Due to the scarcity of available water for replenishing water losses during roosting and flight, open bodies of water of many shapes and sizes may well be a key resource influencing the survival, activity, resource use and the distribution of insectivorous bats. In this chapter, we review the current knowledge of bats living in semi- and arid regions around the world and discuss the factors that influence their richness, behaviour and activity around bodies of water. We further present how increased anthropogenic changes in hydrology and water availability may influence the distribution of species of bats in desert environments and offer directions for future research on basic and applied aspects on bats and the water they use in these environments
Efficient Syntheses of Biobased Terephthalic Acid, p-Toluic Acid, and p-Methylacetophenone via One-Pot Catalytic Aerobic Oxidation of Monoterpene Derived Bio-p-cymene.
An efficient elevated-pressure catalytic oxidative process (2.5 mol % Co(NO3)2, 2.5 mol % MnBr2, air (30 bar), 125 °C, acetic acid, 6 h) has been developed to oxidize p-cymene into crystalline white terephthalic acid (TA) in ∼70% yield. Use of this mixed Co2+/Mn2+ catalytic system is key to obtaining high 70% yields of TA at relatively low reaction temperatures (125 °C) in short reaction times (6 h), which is likely to be due to the synergistic action of bromine and nitrate radicals in the oxidative process. Recycling studies have demonstrated that the mixed metal catalysts present in recovered mother liquors could be recycled three times in successive p-cymene oxidation reactions with no loss in catalytic activity or TA yield. Partial oxidation of p-cymene to give p-methylacetophenone (p-MA) in 55-60% yield can be achieved using a mixed CoBr2/Mn(OAc)2 catalytic system under 1 atm air for 24 h, while use of Co(NO3)2/MnBr2 under 1 atm O2 for 24 h gave p-toluic acid in 55-60% yield. Therefore, access to these simple catalytic aerobic conditions enables multiple biorenewable bulk terpene feedstocks (e.g., crude sulfate turpentine, turpentine, cineole, and limonene) to be converted into synthetically useful bio-p-MA, bio-p-toluic acid, and bio-TA (and hence bio-polyethylene terephthalate) as part of a terpene based biorefinery
Analisi comparativa delle prestazioni relative al running di tre differenti applicazioni scientifiche su singolo pc, su cluster e su infrastruttura GRID
Global patterns of functional trait variation along aridity gradients in bats
Aim Our understanding of the biological strategies employed by species to cope with challenges posed by aridity is still limited. Despite being sensitive to water loss, bats successfully inhabit a wide range of arid lands. We here investigated how functional traits of bat assemblages vary along the global aridity gradient to identify traits that favour their persistence in arid environments. Location Global. Time period Contemporary. Major taxa studied Bats. Methods We mapped the assemblage-level averages of four key bat traits describing wing morphology, echolocation and body size, based on a grid of 100-km resolution and a pool of 915 bat species, and modelled them against aridity values. To support our results, we conducted analyses also at the species level to control for phylogenetic autocorrelation. Results At the assemblage level, we detected a rise in values of aspect ratio, wing loading and forearm length, and a decrease in echolocation frequency with increasing aridity. These patterns were consistent with trends detected at the species level for all traits. Main conclusions Our findings show that trait variation in bats is associated with the aridity gradient and suggest that greater mobility and larger body size are advantageous features in arid environments. Greater mobility favours bats' ability to track patchy and temporary resources, while the reduced surface-to-volume ratio associated with a larger body size is likely to reduce water stress by limiting cutaneous evaporation. These findings highlight the importance of extending attention from species-specific adaptations to broad scale and multispecies variation in traits when investigating the ability of species to withstand arid conditions.Peer reviewe
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