A consolidating product based on nanoparticles of slaked lime (Ca(OH)
2) dispersed in isopropyl alcohol was exposed under different relative humidities (RH), 33%, 54%, 75% and 90% during 7, 14, 21 ...and 28
days. The characterization of the calcium hydroxide nanoparticles and the formed calcium carbonate polymorphs have been performed by Micro Raman spectroscopy, Transmission Electron Microscopy (TEM), Environmental Scanning Electron Microscopy (ESEM) with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). Precipitation and transformation of calcium carbonate polymorphs strongly depend on the relative humidity (RH). Higher RH (75%–90% RH) gives rise to amorphous calcium carbonate and monohydrocalcite, calcite, aragonite and vaterite, faster carbonation and larger particles sizes with higher crystallinity compared to lower RH (33%–54% RH) that gives rise mainly to portlandite and vaterite, slower carbonation and smaller particle sizes with lower crystallinity.
Ca(OH)
2 nanoparticles dispersed in isopropyl alcohol exposed under different relative humidities (RH) 7, 14, 21 and 28 days. Higher RH (75%–90% RH): faster carbonation (amorphous CaCO
3, CaCO
3·H
2O, calcite, aragonite and vaterite) and larger particles sizes with higher crystallinity. Lower RH (33%–54% RH): mainly portlandite (Ca(OH)
2) and vaterite with smaller particle sizes and lower crystallinity.
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Understanding the factors and mechanisms shaping differences in species composition across space and time (β‐diversity) in human‐modified landscapes has key ecological and applied implications. This ...topic is, however, challenging because landscape disturbance can promote either decreases (biotic homogenization) or increases (biotic differentiation) in β‐diversity. We assessed temporal differences in intersite β‐diversity of medium‐bodied and large‐bodied mammals in the fragmented Lacandona rainforest, Mexico. We hypothesized that, given the relatively short history of land‐use changes in the region, and the gain and loss of some species caused by landscape spatial changes, β‐diversity would increase through time, especially its nestedness component. We estimated β‐diversity between 24 forest sites (22 forest patches and two continuous forest sites) in 2011 and 2017 to assess whether β‐diversity is decreasing or increasing in the region, and calculated its turnover and nestedness components to understand the mechanisms responsible for changes in β‐diversity, separately assessing mammal groups with different body mass, feeding guild, and habitat specialization. We then related such temporal changes in β‐diversity to temporal changes in five landscape variables (forest cover, matrix openness, number of patches, edge density and interpatch distance) to identify the landscape drivers of β‐diversity. In contrast with our expectations, β‐diversity decreased over time, suggesting an ongoing biotic homogenization process. This pattern was mostly driven by a decrease in species turnover in all mammal groups, especially in landscapes with decreasing forest cover and increasing forested matrices. Although the nestedness component showed a three‐fold increase through time, species turnover was 22 and six times higher than nestedness in 2011 and 2017, respectively. The decreased turnover appears to be driven by an increase in dispersal (i.e., spillover) of native species among patches. The prevalence of species turnover over nestedness indicates that different forest sites have a fairly distinct subset of species (i.e., high complementarity in species composition). Therefore, conserving all remaining forest patches and increasing forest cover is of utmost importance to effectively maintain β‐diversity and conserve the total diversity (γ) of mammal assemblages in this Mesoamerican biodiversity hotspot.
Background
Geant4 is a Monte Carlo code extensively used in medical physics for a wide range of applications, such as dosimetry, micro‐ and nanodosimetry, imaging, radiation protection, and nuclear ...medicine. Geant4 is continuously evolving, so it is crucial to have a system that benchmarks this Monte Carlo code for medical physics against reference data and to perform regression testing.
Aims
To respond to these needs, we developed G4‐Med, a benchmarking and regression testing system of Geant4 for medical physics.
Materials and Methods
G4‐Med currently includes 18 tests. They range from the benchmarking of fundamental physics quantities to the testing of Monte Carlo simulation setups typical of medical physics applications. Both electromagnetic and hadronic physics processes and models within the prebuilt Geant4 physics lists are tested. The tests included in G4‐Med are executed on the CERN computing infrastructure via the use of the geant‐val web application, developed at CERN for Geant4 testing. The physical observables can be compared to reference data for benchmarking and to results of previous Geant4 versions for regression testing purposes.
Results
This paper describes the tests included in G4‐Med and shows the results derived from the benchmarking of Geant4 10.5 against reference data.
Discussion
Our results indicate that the Geant4 electromagnetic physics constructor G4EmStandardPhysics_option4 gives a good agreement with the reference data for all the tests. The QGSP_BIC_HP physics list provided an overall adequate description of the physics involved in hadron therapy, including proton and carbon ion therapy. New tests should be included in the next stage of the project to extend the benchmarking to other physical quantities and application scenarios of interest for medical physics.
Conclusion
The results presented and discussed in this paper will aid users in tailoring physics lists to their particular application.
Stone-mortar specimens manufactured with limestone and commercial stone-repair hydraulic mortars have been exposed to accelerated ageing tests, salt crystallisation (mixture of sodium chloride, ...sodium sulphate, calcium sulphate and potassium nitrate) and acid vapours exposure (sulphurous and nitric acid) besides, their corresponding control specimens were exposed to deionized water imbibition cycles and water vapour, respectively. Large amounts of soluble nitrates and minor amounts of sulphates precipitate on the surface of both stone and mortar materials after the acid test. This mainly affects the surface of the specimens rather than the stone-mortar interface. Whereas parallel fissures to the interface show up due to salt mixture crystals precipitation after the salt crystallisation test. A remarkable yellowing of the stone takes place after both tests. The mortar with closest properties to Euville limestone, with no phyllosilicates is the most resistant. It shows good mechanical properties but bad hydric interactions with the stone that could prove damaging in the long run. The mortar with the highest porosity and better hydric behavior but poor mechanical interaction with the stone is highly affected by the ageing tests, acting more as a sacrificial mortar rather than as a repair mortar.
The indoor environment and its natural dynamics in small Spanish historical churches such as the studied here depend on the variations of outdoor climate and the moisture dynamics of walls, built ...with different materials. Such indoor environments are impacted by local factors, which may put at risk the conservation of a church's cultural assets. Natural ventilation in spring, the presence of people and especially the wintertime use of ageing heating system induce substantial fluctuations in indoor environments primarily affecting the stability of relative humidity (RH). RH is the physical parameter that can induce efflorescence as well as plaster blistering and detachment in its inside walls, drying and cracking in the timber and efflorescence and disgregation in the carved dolostone. Where the RH inside building is not high, as in the present case, natural and induced fluctuations may lower it considerably (<25%), which is detrimental to conservation and human well-being both. Human presence partially counters the steep declines in RH attributable to heating in winter and warm, dry summer weather, although the trade-off is a rise in CO2 levels inside the church. Heating induces substantial changes in the T and RH on the high altar and in the upper areas of the nave, while natural ventilation affects the RH at the base of the church and favours the elimination of CO2. The results obtained have allowed us to develop a series of recommendations that might be useful for the preventive conservation of such historic buildings, without compromising human comfort.
•The indoor environment in rural church depends on outdoor climate and moisture of walls.•The indoor environment is impacted by local factors, which may put at risk the heritage conservation.•Natural ventilation, presence of people and heating system induce fluctuations in indoor environments.•The three factors primarily affect the stability of inside relative humidity which is generally low.•The deterioration caused by these severe fluctuations is important, so its control is necessary for conservation.
Anthocyanins and tannins are two of the most abundant flavonoids found in grapevine, and their synthesis is derived from the phenylpropanoid pathway. As described for model species such as ...Arabidopsis thaliana, maize and petunia, the end-point branches of this pathway are tightly regulated by the combinatorial interaction of three families of regulatory factors; MYB, bHLH (also known as MYC) and WDR proteins. Among these, only MYB genes have been previously identified in grapes. Here, we report the isolation of the first members from the WDR and bHLH families found in Vitis vinifera, named WDR1, WDR2 and MYCA1. WDR1 contributed positively to the accumulation of anthocyanins when it was overexpressed in A. thaliana, although it was not possible to determine the function of WDR2 by ectopic expression. The sub-cellular localizations of WDR1 and MYCA1 were observed by means of GFP-fusion proteins, indicating both cytoplasm and nuclear localization, in contrast to the localization of a MYB factor exclusively in the nucleus. The expression patterns of these genes were quantified in coloured reproductive organs throughout development, and correlated with anthocyanin accumulation and the expression profiles of the flavonoid-related MYBA1-2, UFGT, and ANR genes. In vitro grapevine plantlets grown under high salt concentrations showed a cultivar-dependent response for anthocyanin accumulation, which correlated with the expression of MYBA1-2, MYCA1 and WDR1 genes. These results suggest that MYCA1 may regulate ANR and UFGT and that this last control is easier to distinguish whenever MYBA genes are absent or in low abundance. Future studies should address the specific interactions of these proteins and their quantitative contribution to flavonoid synthesis in grape berries.
City of Play Arce, Rodrigo Pérez de
2018, 2018-05-31
eBook
'City of Play' shows how play is built into the very fabric of the modern city. From playgrounds to theme parks, skittle alleys to swimming pools, to the countless uncontrolled spaces which the urban ...habitat affords - play is by no means just a childhood affair. A myriad essentially unproductive playful pursuits have, through time, modelled the modern city and landscape. Architect and scholar Rodrigo Pérez de Arce's erudite, original, and often surprising study explores a curiously neglected dimension of architectural design and practice: ludic space.
In the 1960s, the Quintero industrial complex was inaugurated in Chile. This began a history of dramatic anthropogenic impacts on the Chilean coast. Among the known, we could mention high atmospheric ...emissions of chemicals due to combustion processes and frequent oil spills. For this reason, we surveyed the concentrations of fifteen EPAPAHs in the surface coastal waters of the Quintero Bay area in 2015. The levels found are in the range of the highest levels when reviewing the literature (0.97 μg L−1 up to 9.84 μg L−1). The highest levels were found in the vicinity of the industrial complex and decreased in the other two zones. The concentration of individual compounds significantly exceeds the levels recommended by the EPA (Environmental Protection Agency) and the EU water framework directive (WFD). The risk estimations revealed that PAH concentrations represent high-risk for wildlife. Molecular ratios of PAHs were used to identify the possible sources, being these were mainly of pyrogenic origin, agreeing with an origin in the combustion of wood, coal, grass, and fossil fuels. This study contributes to the first data for surface water in a country's highly impacted industrial coastal area.
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•Surface seawater concentrations of PAHs were surveyed in three sites influenced by the Industrial complex of Quintero (Chile).•Concentrations reported were in the upper range of the reported bibliography•Source appointment using molecular ratios revealed pyrogenic origin and mainly from combustion processes of fuel, coal and wood.•The levels found in the study area exceed international quality guidelines for compounds that follow some type of regulation.
Carbon nanomaterials have received increased attention in the last few years due to their potential applications in several areas. In medicine, for example, these nanomaterials could be used as ...contrast agents, drug transporters, and tissue regenerators or in gene therapy. This makes it necessary to know the behavior of carbon nanomaterials in biological media to assure good fluidity and the absence of deleterious effects on human health. In this work, the rheological characterization of different graphene nanomaterials in fetal bovine serum and other fluids, such as bovine serum albumin and water, is studied using rotational and microfluidic chip rheometry. Graphene oxide, graphene nanoplatelets, and expanded graphene oxide at concentrations between 1 and 3 mg/mL and temperatures in the 25-40 °C range were used. The suspensions were also characterized by transmission and scanning electron microscopy and atomic force microscopy, and the results show a high tendency to aggregation and reveals that there is a protein-nanomaterial interaction. Although rotational rheometry is customarily used, it cannot provide reliable measurements in low viscosity samples, showing an apparent shear thickening, whereas capillary viscometers need transparent samples; therefore, microfluidic technology appears to be a suitable method to measure low viscosity, non-transparent Newtonian fluids, as it is able to determine small variations in viscosity. No significant changes in viscosity are found within the solid concentration range studied but it decreases between 1.1 and 0.6 mPa·s when the temperature raises from 25 to 40 °C.
Slaked lime (Ca(OH)
2) nanoparticles were exposed at 33% and 75% relative humidity (RH) to consolidate dolostone samples used in historical buildings. Non-destructive techniques (NDT) were applied to ...determine the chemical, morphological, physical and hydric properties of the stone samples, before and after 20
days treatment. Morphological and mineralogical characterisation of the nanoparticles was performed. 75% RH favors the consolidation process studied under Environmental Scanning Electron Microscopy (ESEM-EDS), spectrophotometry, capillarity, water absorption under vacuum, ultrasound velocity, Nuclear Magnetic Resonance (imaging and relaxometry) and Optical Surface Roughness analyses. At 75% RH the nanoparticles fill the pores and inter-crystalline dolomite grain contacts but do not favor calcite re-crystallization as it occurs at 33% RH. The ESEM, XRD and TEM analyses under 75% RH reveal the fast transformation of portlandite (Ca(OH)
2) into vaterite (CaCO
3), monohydrocalcite (CaCO
3
·
H
2O) and calcite (CaCO
3), and eventually the physical and hydric properties of the stones significantly improve. New insights are provided for the assessment of consolidation effectiveness of porous carbonate stones with calcium hydroxide nanoparticles under optimum RH conditions combining several NDT.
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