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Abstract: Palynological studies including records of non-pollen palynomorphs (NPP) are uncommon in the Neotropics, in spite of their demonstrated usefulness in other regions. Modern analog studies to improve palaeoecological interpretations of NPP are even more scarce. Here, we report the NPP assemblages recorded in modern surface samples from an altitudinal transect of the Venezuelan Andes, ranging from about 2300 and 4600m. We compared the assemblages with the results of previous pollen analyses of the same samples. The variables considered to explain NPP patterns along the transect are altitude and the local habitat of the sampling site (“sample type”). A total of 65 NPP taxa – classified into algal and zoological remains, and fungal spores – have been found. Unidentified taxa (23) have been named with a code, depicted and described for further reference. Fungal spores are well represented along the whole transect, whereas algal and zoological remains are absent or very scarce in the lower and the uppermost ranges. The altitudinal zonation of fungal spores matches with that of pollen and the corresponding vegetation belts, suggesting a close relationship. The known environmental requirements of some of the fungi identified allowed inferences on particular ecological features, in agreement with previous palynological interpretations. Both elevation and sample type are needed to explain the observed differences in the assemblages of the three groups, the elevation being more decissive for fungal spores and the local habitat of the sampling site for algal and zoological remains. The sample type effect is minimised when the NPP studied are considered altogether, thus increasing their usefulness as palaeoecological proxies. This study reinforces the utility of modern analog surveys of NPP with palaeoecological purposes and encourages further research, particularly in poorly known areas, as for example tropical regions. [ABSTRACT FROM AUTHOR]

Abstract: The k 0 method was implemented at the Peruvian Institute of Nuclear Energy (IPEN), by 1993. Since the middle of 1994, almost all INAA work at IPEN is performed by the k 0 method. The establishment, applications, development and future of the method in Peru are presented from a retrospective and prospective view. Attention is paid to difficult aspects, e.g. counting efficiency, characterization of irradiation facility; non-ideal behaviour of the epithermal neutron spectrum and consistency of nuclear input data. [Copyright &y& Elsevier]

Abstract: Objective: To identify the variables that influenced brain-dead donor family groups to refuse donation. Methods: The Tissue and Organ Procurement System in Venezuela designed a tool to register some phases of a family interview performed by transplant coordinators. This tool analyzed three phases. The first phase of the interview allowed the coordinator to evaluate the communication quality with the family group during a brain-death notification. The second phase assessed how families understood this notification, and the third phase identified the family grief sequence. Among the 186 interviews during 2007 to procure tissues and organs for transplantation, 37.63% (n = 70) concluded as family refusals. A retrospective study sought to analyze these results. Results: The average time between notification of brain death and the first approach to the family was 8.78 hours. Setting a place for interviews was done in 91.10% of cases. Previous knowledge about donation was seen in only 53.33% of cases. The main phase of family grief identified was denial (80%). The five reasons for family denial were: absolute denial, family disagreement, uncertainty about the destination of the donated organs and tissues, fear about deformation of the donor''s body, and lack of acceptance of brain death. Conclusions: Brain-death notification produced a deep sadness among family groups. There was a lack of knowledge regarding donation of tissues and organs. It was impossible to quantify the time needed by families to understand and accept brain death and to identify the grief sequence in order to avoid family refusals. [Copyright &y& Elsevier]

New constitutive models for confined concrete were formulated and implemented into in-house nonlinear finite element programs at the University of Toronto. A program for analysis of axisymmetric solids was specifically developed for this work. The confinement models proposed follow a compression field modelling approach that combines nonlinear elasticity and plasticity-type modelling. In this paper, the formulations are corroborated by examining the behaviour of reinforced concrete columns confined with fibre reinforced polymers (FRP), steel, or a combination of both. The analytical responses agree well with the experimental results, showing the capabilities of the models to reasonably model pre- and post-peak behaviour, and strength enhancement. [Copyright &y& Elsevier]

We describe the growth of high quality transparent fibers of pure and Nd-doped YAlO3 from unreacted pedestals (green rods) by the laser heated pedestal growth technique. The X-ray diffraction analysis shows that the fibers are monocrystalline, with a distorted Pnma perovskite structure and grow along 〈0 1 0〉 direction (b axis). In this work, multi-wavelength laser action is demonstrated for these fibers in the two main laser channels of Nd3+ ions. In the 4F3/2 → 4I11/2 laser transition, low threshold multi-wavelength laser emission is obtained at wavelengths of 1065, 1073 and 1081 nm. Additionally, for the first time in LHPG grown YAlO3 fibers, laser action in the 4F3/2 → 4I13/2 transition is demonstrated at a wavelength of 1341 nm. [Copyright &y& Elsevier]

Geochemical (major oxides, trace and rare earth elements) studies were carried out on the siliciclastic rocks of the Antimonio and Río Asunción formations to interpret the paleoweathering conditions and provenance. The weathering indices like the Chemical Index of Alteration (CIA) and Plagioclase Index of Alterations (PIA) indicate a low to moderate intensity of chemical weathering. The chondrite normalized REE patterns of the Antimonio and Río Asunción formations have LREE enriched, flat HREE patterns with a negative Eu anomaly. However, a few samples from these formations show a positive or an absence of the Eu anomaly, suggesting that the sediments were dominantly derived from felsic source rocks with a minor contribution from mafic source rocks. The vertical distribution of trace elements and their ratios indicate that sequence I of the Antimonio Formation presents a signature for felsic source rocks, however, in sequence II the sediment source changed, i.e. mafic rocks were recorded (SAAF06 and SAAF07). Sequences III to VI indicate a felsic source rock. The basal and upper parts of sequence VII (samples SARAF02 and SARAF10) of the Río Asunción Formation indicate mafic source rocks, whereas the remaining samples were largely contributed by felsic source rocks. The lower values of ferromagnesian trace elements and their ratios in sequences VIII and IX reveal a felsic source for the upper part of the Río Asunción Formation. The Antimonio and Río Asunción formations received sediments from two different sources: Permo-Triassic granitoids of northwestern Sonora and Precambrian granitoids from Caborca and North American blocks that contributed felsic rocks. Whereas mafic elements were derived from Precambrian amphibolites and Cambrian basalts located north and south of the study area. • The Antimonio and Rio Asuncion formations received sediments from the sources rocks affected by low to moderate intensity of chemical weathering conditions. • On chondrite normalized diagrams, most samples have LREE enriched, flat HREE patterns with negative Eu anomalies whereas few samples show positive Eu anomalies. • The elemental ratios, bivariate and ternary diagrams indicate a contribution of felsic sources for most samples of both formations. • The values of the weathering indices indicate that the Late Permian-Triassic periods were dominated by arid and semi-arid climates. [ABSTRACT FROM AUTHOR]

One way to decarbonize the heat production sector is to gradually replace natural gas with hydrogen. The design of laminar premixed burners capable of operating with both methane and hydrogen is however challenging as these fuels have drastically different burning properties, which narrows the operating range. While methane flames face limitations in stabilization due to blow-off at high power, hydrogen flames tend to be susceptible to flashback at low power. This study investigates the effects of slits symmetry breaking on the blow-off of methane flames and flashback of hydrogen flames through two-dimensional direct numerical simulations of canonical asymmetrical slit configurations, revealing uneven interactions between the main openings and smaller auxiliary slits. The equations governing the reactive flow dynamics are coupled to a heat transfer solver in the solid phase to elucidate the thermal and hydrodynamic mechanisms determining the operability limits. Viscous dissipation in the small auxiliary slits together with a substantial preheating of the fresh gases by heat redistribution through the solid phase is found to govern flame stabilization in asymmetrical geometries, improving blow-off resistance of methane-air flames. Then, flashback of hydrogen-air flame is found to be driven by the competition between (i) the mass flow rate distribution between the main and auxiliary slits, (ii) preheating of the gas through the auxiliary slits and (iii) the ability of the main and auxiliary slits to quench the flame. The interplay of these phenomena gives rise to complex behaviors, wherein asymmetrical configurations could exhibit significantly enhanced resistance to flashback compared to symmetrical geometries. This conclusion, verified for different burner thicknesses and slit spacing, may be used to guide the design of fuel-flexible laminar burners. Novelty and significance statement 1. Analyzing the effect of slits symmetry breaking on blow-off of methane flames and flashback of hydrogen flames for multi-perforated laminar burners. 2. Defining a strategy for wall heat flux redistribution to assess the asymmetrical interaction between the main and auxiliary flames through the flame-holder. 3. Demonstrating and explaining the positive impact of symmetry breaking on the blow-off resistance of methane flames. 4. Highlighting the substantial and non-monotonous impact of symmetry breaking on hydrogen flame flashback. 5. Identifying the interplay of thermal and hydrodynamic mechanisms in asymmetrical slits leading to improvement of flashback resistance for hydrogen-air flames compared to symmetrical configurations. [ABSTRACT FROM AUTHOR]

The Younger Dryas (YD) climatic reversal (12.86–11.65 cal ky BP), especially the warming initiated at ∼12.6 cal ky BP, and the associated vegetation changes have been proposed as past analogs to forecast the potential vegetation responses to future global warming. In this paper, we applied this model to highland and midland Neotropical localities. We used pollen analysis of lake sediments to record vegetation responses to YD climatic changes, which are reconstructed from independent paleoclimatic proxies such as the Mg/Ca ratio on foraminiferal tests and Equilibrium Line Altitude (ELA) for paleotemperature, and grayscale density and Titanium content for paleoprecipitation. Paleoclimatic reconstructions at both highlands and midlands showed a clear YD signal with a conspicuous warming extending into the early Holocene. A small percentage of taxa resulted to be sensitive to these YD climate changes. Response lags were negligible at the resolution of the study. However, changes in the sensitive taxa were relevant enough to determine changes in biodiversity and taxonomic composition. Highland vegetation experienced mainly intra-community reorganizations, whereas midland vegetation underwent major changes leading to community substitutions. This was explained in terms of threshold-crossing non-linear responses in which the coupling of climatic and other forcings (fire) was proposed as the main driving mechanism. Paleoecology provides meaningful insights on the responses of highland and midland Neotropical vegetation to the YD climatic reversal. Biotic responses at both individual (species) and collective (assemblage) levels showed patterns and processes of vegetation change useful to understand its ecological dynamics, as well as the mechanisms and external drivers involved. The use of paleoecological methods to document the biotic responses to the YD climate shifts can be useful to help forecasting the potential consequences of future global warming. Due to its quasi-global character, the YD reversal emerges as a well suited candidate for providing useful insights of global scope by analyzing the corresponding biotic responses virtually at any geographical and biological setting. [ABSTRACT FROM AUTHOR]

Abstract: Ionic gelation is the most frequently used method to obtain chitosan–tripolyphosphate nanoparticles due to its simplicity and because it does not generate waste solvents in the samples prepared. This paper presents a study of the physical factors involved in this method for obtaining nanoparticles in order to determine which of them significantly influences the particle size of polymeric nanoparticles made from low-molecular-weight chitosan, without any additional chemical treatment, with the aim of standardising and optimising the method conditions, in addition to establishing the reaction yield. The results indicate that stirring speed during ionic gelation reaction is decisive for the size of the nanoparticles obtained. Furthermore, it thus follows that the stirring speed during ionic gelation significantly affects reaction yield, and therefore, by manipulating this parameter a greater proportion of nanoparticles of a given size range can be obtained. [Copyright &y& Elsevier]

Abstract: Palaeoecology, as an ecological discipline, is able to provide relevant inputs for conservation science and ecosystem management, especially for issues involving long-term processes, such as ecological succession, migration, adaptation, microevolution, and extinction. This use of palaeoecology has been noted for several decades, and it has become widely accepted, especially in the frame of ongoing and near-future global warming and its potential biotic consequences. Selected palaeoecological insights of interest for conservation include the following: 1) species respond in an individualistic manner to environmental changes that lead to changes in community composition, suggesting that future ecosystems would have no modern analogues; 2) in the short-term, acclimation is more likely a response of species that are expected to persist in the face of global warming, but the possibility of evolutionary change linked to the existence of pre-adapted genomes cannot be dismissed; 3) species unable to acclimate or adapt to new conditions should migrate or become extinct, which has been observed in past records; 4) current extinction estimates for the near-future should be revised in light of palaeoecological information, which shows that spatial reorganisations and persistence in suitable microrefugia have been more common than extinction during the Quaternary; 5) biotic responses to environmental changes do not necessarily follow the rules of equilibrium dynamics but depend on complex and non-linear processes that lead to unexpected “surprises”, which are favoured by the occurrence of thresholds and amplifying positive feedbacks; 6) threshold responses can cause the movement of ecosystems among several potentially stable states depending on their resilience, or the persistence of transient states; 7) species and their communities have responded to environmental changes in a heterogeneous fashion according to the local and regional features, which is crucial for present and future management policies; 8) the global warming that occurred at the end of the Younger Drays cold reversal (ca 13.0 to 11.5 cal kyr BP) took place at similar rates and magnitudes compared to the global warming projected for the 21st century, thus becoming a powerful past analogue for prediction modelling; 9) environmental changes have acted upon ecosystems in an indirect way by modifying human behaviour and activities that, in turn, have had the potential of changing the environment and enhancing the disturbance effects by synergistic processes involving positive feedbacks; 10) the collapse of past civilisations under climate stress has been chiefly the result of inadequate management procedures and weaknesses in social organisation, which would be a warning for the present uncontrolled growth of human population, the consequent overexploitation of natural resources, and the continuous increase of greenhouse gas emissions; 11) the impact of fire as a decisive ecological agent has increased since the rise of humans, especially during the last millennia, but anthropic fires were not dominant over natural fires until the 19th century; 12) fire has been an essential element in the development and ecological dynamics of many ecosystems, and it has significantly affected the worldwide biome distribution; 13) climate–fire–human synergies that amplify the effects of climate, or fire alone, have been important in the shaping of modern landscapes. These general paleoecological observations and others that have emerged from case studies of particular problems can improve the preservation of biodiversity and ecosystem functions. Nature conservation requires the full consideration of palaeoecological knowledge in an ecological context, along with the synergistic cooperation of palaeoecologists with neoecologists, anthropologists, and conservation scientists. [Copyright &y& Elsevier]

The Morita Formation is a Lower Cretaceous unit of the Bisbee Group that crops out in northern Sonora and southeastern Arizona where it was deposited within the Altar-Cucurpe, and Huachuca sub-basins of the Bisbee basin, respectively. In northern Sonora it either overlies strata of the Upper Jurassic Cucurpe Formation, the Glance Conglomerate, or strata of the Lower Cretaceous Cerro de Oro/Rancho La Colgada formations, and it grades upward into the Mural Limestone. In this contribution we characterize the stratigraphy, petrography and detrital zircon geochronology of the Morita Formation along a ca. 60 km-long northwest-southeast transect that includes the complete columns of the Mule Mountains in southeastern Arizona and the sierras San José, Anibacachi and Rancho Búfalo area in northeastern Sonora. Thickness of these sections varies from a minimum of 555 m in Sierra Anibacachi to a maximum of 855 m in Rancho Búfalo. In most sections, the lower half of the Morita consists of reddish siltstone and mudstone with pedogenic calcareous nodules with interbeds of mostly single-storey sandstone bodies, which changes to isolated multi-storey sandstone bodies in its upper half. In contrast, the lower part of the Rancho Búfalo column consists of reddish mudstone/siltstone with isolated, fining-upward, clast-supported, fine-pebble conglomerate beds that grades into reddish to purple, brown and green mudstone/siltstone with isolated, single-storey to multi-storey sandstone beds of its upper part. Lithofacies association in the Morita Formation suggest it is of fluvial origin but ichnofossils and local herringbone- and flaser-cross bedding in its upper part indicate intermitent marginal marine sedimentation preceding the transgression that deposited the overlying Mural shelf. Sandstone composition of the Mule and San José mountains is dominantly feldspatho-quartzose indicating dominant provenance from basement uplift and transitional continental areas, while composition at Sierra Anibacachi and Rancho Búfalo ranges from feldspatho litho-quartzose to litho-quartzose, indicating provenance from recycled orogen. Detrital zircon grains dated from samples of all the studied sections share very similar populations of Proterozoic to Mesozoic ages, but the Mesoproteozoic and Triassic grains compose ca. 64% of the total grains. Detrital zircon grains of Lower Cretaceous age that are only present in samples from the bottom of the Mule and San José Mountains help to constrain a maximum depositional age of 125.5 ± 0.8 Ma for inception of sedimentation of the Morita Formation in this region. According to this age and to observed stratigraphic relationships, we interpret that the lower contact of the Morita Formation is a disconformity with the underlying Glance Conglomerate, or with the Cerro de Oro Formation in northeastern Sonora. Similarly, according to regional stratigraphic relationships and age data known from the Cucurpe-Tuape region, in north-central Sonora, the age of this unit may be constrained to the Aptian stage, in Sonora, from ca. 125 to 115 Ma. Regional isopach curves confirm merging of the sub-basins in northeastern Sonora, continuous sedimentation of the Morita Formation, and presence of the Cananea high separating them. • The Morita Formation is a regional Lower Cretaceous unit of the Bisbee Group. • Its thickness range from 555 to 855 m from SE Arizona to NE Sonora. • Lithofacies indicate a mostly fluvial origin with marine influence in its upper part. • Its regional age can be constrained to the Aptian Stage, from ca. ca. 125 to 115 Ma. [ABSTRACT FROM AUTHOR]

The detection of Salmonella in food is based on the use of a selective enrichment broth such as Muller-Kauffman Tetrathionate-Novobiocin (MKTTn), in which tetrathionate plays a key role by providing Salmonella with a growth advantage. As sodium tetrathionate is unstable, it is generated in situ by the addition of iodine (Lugol's solution) before seeding. This step is cumbersome as the solution is easily spilled, compromising the performance of the medium and hindering the work of technicians. The aim of this study was to optimize MKTTn broth by generating tetrathionate ex situ through an external reaction between iodine and thiosulphate followed by lyophilization. Quality control procedures were performed to compare the modified and original media, testing pure productivity (enrichment with 50–120 CFU of Salmonella Thyphimurium ATCC 14028 and Salmonella Enteritidis ATCC 13076 and plating on Xylose Lysine Deoxycholate agar, XLD), mixed productivity (50–120 CFU of Salmonella strains and Pseudomonas aeruginosa and Escherichia coli at ≥104 CFU and XLD plating) and selectivity (≥104 CFU of P. aeruginosa and Enterococcus faecalis and plating on Tryptone Casein Soy agar, TSA). The modified MKTTn medium (S/L) performed comparably with the original medium in terms of growth of both Salmonella strains (>300 colonies in XLD), alone or with P. aeruginosa and E. coli. Quantitative assays showed no statistically significant differences in the number of colonies grown on XLD after 10−5 dilution (p = 0.7015 with S. Thyphimurium ATCC 14028 and p = 0.2387 with S. Enteritidis ATCC 13076; ANOVA test). MKTTn medium (S/L) was also selective against E. coli (≤100 colonies) and E. faecalis (<10 colonies). These results suggest that adding tetrathionate as a lyophilisate (S/L) is a feasible alternative to the use of Lugol's solution for the preparation of MKTTn enrichment broth and does not affect the properties of the medium. • Adding Lugol's solution before seeding compromises the properties of MKTTn medium. • In the new medium, sodium tetrathionate was externally generated and lyophilized. • Productivity and selectivity of the original and modified MKTTn media were similar. • Adding tetrathionate as a lyophilisate avoids the addition of Lugol's solution. • Lyophilized tetrathionate could be added via a powder or tablet dispenser. [ABSTRACT FROM AUTHOR]

Abstract: Ion channel conformational changes within the lipid membrane are a key requirement to control ion passage. Thus, it seems reasonable to assume that lipid composition should modulate ion channel function. There is increasing evidence that this implicates not just an indirect consequence of the lipid influence on the physical properties of the membrane, but also specific binding of selected lipids to certain protein domains. The result is that channel function and its consequences on excitability, contractility, intracellular signaling or any other process mediated by such channel proteins, could be subjected to modulation by membrane lipids. From this it follows that development, age, diet or diseases that alter lipid composition should also have an influence on those cellular properties. The wealth of data on the non-annular lipid binding sites in potassium channel from Streptomyces lividans (KcsA) makes this protein a good model to study the modulation of ion channel structure and function by lipids. The fact that this protein is able to assemble into clusters through the same non-annular sites, resulting in large changes in channel activity, makes these sites even more interesting as a potential target to develop lead compounds able to disrupt such interactions and hopefully, to modulate ion channel function. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. [Copyright &y& Elsevier]

Abstract: An evaluation of the accuracy in the application of the k0 -INAA method using Zn foil as comparator is presented. A good agreement was found in the precision within analysts and between them, as well as in the assessment of trueness for most elements. The determination of important experimental parameters like gamma peak counting efficiency, γ–γ true coincidence, comparator preparation and quality assurance/quality control is also described and discussed. [Copyright &y& Elsevier]

Abstract: Inhibition of red delicious apple polyphenol oxidase (PPO) by three non-related antibrowning agents has been studied at different substrate concentrations. The main apple polyphenol, cholorogenic acid (CA), has been used as a substrate. The three agents (β-cyclodextrin [β-CD], 4-hexylresorcinol [HR] and methyl jasmonate [MJ]) showed an inhibitory effect at every substrate concentration tested. From the inhibition constant (K i) values, it was concluded that the inhibitors’ strength decreased in the order HR>β-CD>MJ. A combination of β-CD-HR had a synergic effect, which was not observed for the combination of β-CD-MJ. A competitive-type inhibition was obtained for HR with a K i =0.26mM. β-CD and MJ behaved as mixed-type inhibitors, although more than one inhibitory mechanism is discussed for both agents. [Copyright &y& Elsevier]