Agrochemical contamination and ageing effects on greenhouse plastic film for recycling

Polymers are employed in agriculture in several applications, the most efficient and fruitful of which is the protection of cultivations through the use of cover placed over plants while they are growing, providing protection from climatic factors, while at the same time increasing yield and/or extending the cropping season. Plastic films used for covering greenhouses, low and medium tunnel and for soil mulching have reached very notable consumptions all over Europe as well as the rest of the World, posing an important environmental problem connected with the impact that plastic material has on the sustainability of the agricultural production, whose environmental footprint may be deteriorated. Recycling agricultural plastics is a common technique, but it has not yet solved the problem of their re-use in the framework of a circular economy, since many factors are still anyway limiting the mechanical recycling of agricultural plastic materials. Among these limiting factors, the loss of mechanical properties of plastic film, due to its ageing after being exposed to direct solar radiation plays a crucial role, mostly if aggravated by the contamination with agrochemicals ordinarily used for crop health and pest management. In the present paper, the results of some laboratory tests on agricultural plastic film artificially aged for different periods contaminated with two different agrochemicals, are reported. These results have showed that the impact of agrochemicals on the plastic film is considerable already in the use-phase, so when entering the recycling stage, the material carries a low potential for being transformed into a closed-loop recycled material. The results in terms of Carbonyl Index (CI) have confirmed the tendency of the material to degrade rapidly when in contact with anti-aphid or fungicide contaminants. The samples sprayed with agrochemicals experience a considerable increase in CI values after 4 weeks of ageing, which makes impossible the mechanical recycling of this material

2D Kagome Ordering in the 3D Frustrated Spinel Li2Mn2O4

muSR experiments on the geometrically frustrated spinel oxide, Li2Mn2O4, show the development of spin correlations over a range of length scales with decreasing temperature. Increased relaxation below 150 K is consistent with the onset of spin correlations. Below 50 K, spin order on a length scale, which is long range for the muSR probe, appears abruptly in temperature, consistent with prior neutron diffraction results. The oscillations in the zero field asymmetry are analyzed using a three frequency model. By locating the muon site this is shown to be consistent with the unexpected 2D q = root 3 x root 3 structure on the Kagome planes proposed originally from neutron data. Longitudinal field data demonstrate that some spin dynamics persist even at 2 K. Thus, a very complex magnetic ground state, featuring the co-existence of long length scale 2D ordering and significant spin dynamics, is proposed. This is unusual considering the 3D topology of the Mn3+ spins in this material.Comment: 9 pages, 9 figures, to be submitted to J. Phys. Cond. Mat

Genetic Analysis of a Cryptic Contact Zone between Mitochondrial Clades of the Eastern Red-Backed Salamander, Plethodon cinereus

When evolutionarily divergent lineages adjoin their geographic ranges after a period of isolation, myriad outcomes can occur, from population anastomosis to the evolution of reproductive isolation by way of reinforcement. Hybrid zones represent natural experiments that may indicate whether lineages will maintain their evolutionary independence. Here, we report on a hybrid zone in the Eastern Red-Backed Salamander, Plethodon cinereus, a highly abundant and wide-ranging terrestrial salamander found in the northeastern United States and in southeastern Canada. An earlier study identified six distinct mitochondrial clades across the range of P. cinereus. Populations of two of these clades were as close as 9.6 km apart in Lorain County, Ohio, USA. To investigate the nature of this contact zone, we sampled 316 individuals from 16 sites along a 53-km transect, and analyzed 10 microsatellite loci and one mitochondrial locus. We found a clinal transition for mtDNA haplotypes. In contrast, most studies of terrestrial plethodontid salamanders commonly exhibit sharp boundaries between mtDNA clades. Microsatellite markers, however, revealed little differentiation and weak population structure, suggesting the nuclear cline, if it exists, lies outside of our sampling region. Explanations for the discordance between the mitochondrial DNA and our microsatellite data include lineage sorting, male-biased dispersal, or historical introgression of mtDNA, among other possibilities. We compare our results with other studies of introgression in terrestrial salamanders, and discuss the causes of mitonuclear discordance

Hermitian boson mapping and finite truncation

Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are also finite (e.g., a 1+2-body fermion Hamiltonian is mapped to a 1+2-body boson Hamiltonian) in the truncated basis. For the most general case, where the image is not necessarily exactly finite, we discuss how to make practical and controlled approximations.Comment: 12 pages in RevTex with no figures, Los Alamos preprint # LA-UR-94-146

Hybridization between the Woodland Salamanders Plethodon cinereus and P. electromorphus Is Not Widespread

A recent study reported widespread hybridization between the Eastern Red-backed Salamander (Plethodon cinereus) and the Northern Ravine Salamander (P. electromorphus) in northern Ohio. In this study, DNA sequence data were obtained from three nuclear loci and 20 single nucleotide polymorphisms (SNPs) were identified from the sequences. They found that 48 out of 90 individuals from 13 populations were hybrids, and in some localities every individual possessed an admixed genotype. As these results contradict our observations, and because levels of hybridization impact our interpretation of past and ongoing studies, we revisited the data. First we reanalyzed the original SNPs using STRUCTURE, then we repeated the analysis using haplotypes instead of SNPs. We found that K1⁄4 2 was best supported by both analyses, and they agree in recovering lower levels of hybridization than originally reported. For example, five populations in the original study identified as highly admixed or composed entirely of admixed genotypes we found to be pure P. cinereus or to lack evidence of extensive admixture. Similar results were obtained using NEWHYBRIDS and analyses based on gene trees. We conclude that while hybridization between P. cinereus and P. electromorphus occurs, it is much more restricted than originally reported

Elizabeth Cary and Intersections of Catholicism and Gender in Early Modern England

Historians have analyzed the life of Elizabeth Cary, Lady Falkland, primarily in the context of her highly publicized conversion to Catholicism and her equally public separation from her Protestant husband, Henry Cary. Through this scrutiny, she has become one among many English Catholic recusant heroines. Literary critics, in contrast, have celebrated Cary\u27s literary corpus both for its challenge to traditional ideals of early modern women as chaste, silent, and obedient and for its reevaluation of women\u27s roles within marriage.1 To circumscribe our understandings of Cary in such ways obscures one of her greatest contributions. Elizabeth Cary, albeit unintentionally, provided an alternative model of Catholic woman hood that sought to negotiate a new balance between religion and gender, thus challenging assumptions about women\u27s roles in English Catholic communities and about the rigid character of Catholicism in the Reformation era

Pressure effect on the in-plane magnetic penetration depth in YBa_2Cu_4O_8

We report a study of the pressure effect (PE) on the in-plane magnetic field penetration depth lambda_{ab} in YBa_2Cu_4O_8 by means of Meissner fraction measurements. A pronounced PE on lambda_{ab}^{-2}(0) was observed with a maximum relative shift of \Delta\lambda^{-2}_{ab}/\lambda^{-2}_{ab}= 44(3)% at a pressure of 10.2 kbar. It arises from the pressure dependence of the effective in-plane charge carrier mass and pressure induced charge carrier transfer from the CuO chains to the superconducting CuO_2 planes. The present results imply that the charge carriers in YBa_2Cu_4O_8 are coupled to the lattice.Comment: 4pages 3 figure

Speciation with gene flow in a narrow endemic West Virginia cave salamander (\u3ci\u3eGyrinophilus subterraneus\u3c/i\u3e)

Due to their limited geographic distributions and specialized ecologies, cave species are often highly endemic and can be especially vulnerable to habitat degradation within and surrounding the cave systems they inhabit. We investigated the evolutionary history of the West Virginia Spring Salamander (Gyrinophilus subterraneus), estimated the population trend from historic and current survey data, and assessed the current potential for water quality threats to the cave habitat. Our genomic data (mtDNA sequence and ddRADseq-derived SNPs) reveal two, distinct evolutionary lineages within General Davis Cave corresponding to G. subterraneus and its widely distributed sister species, Gyrinophilus porphyriticus, that are also differentiable based on morphological traits. Genomic models of evolutionary history strongly support asymmetric and continuous gene flow between the two lineages, and hybrid classification analyses identify only parental and first generation cross (F1) progeny. Collectively, these results point to a rare case of sympatric speciation occurring within the cave, leading to strong support for continuing to recognize G. subterraneus as a distinct and unique species. Due to its specialized habitat requirements, the complete distribution of G. subterraneus is unresolved, but using survey data in its type locality (and currently the only known occupied site), we find that the population within General Davis Cave has possibly declined over the last 45 years. Finally, our measures of cave and surface stream water quality did not reveal evidence of water quality impairment and provide important baselines for future monitoring. In addition, our unexpected finding of a hybrid zone and partial reproductive isolation between G. subterraneus and G. porphyriticus warrants further attention to better understand the evolutionary and conservation implications of occasional hybridization between the species

The reductive activation of CO2 across a Ti═Ti double bond: synthetic, structural, and mechanistic studies

[Image: see text] The reactivity of the bis(pentalene)dititanium double-sandwich compound Ti(2)Pn(†)(2) (1) (Pn(†) = 1,4-{Si(i)Pr(3)}(2)C(8)H(4)) with CO(2) is investigated in detail using spectroscopic, X-ray crystallographic, and computational studies. When the CO(2) reaction is performed at −78 °C, the 1:1 adduct 4 is formed, and low-temperature spectroscopic measurements are consistent with a CO(2) molecule bound symmetrically to the two Ti centers in a μ:η(2),η(2) binding mode, a structure also indicated by theory. Upon warming to room temperature the coordinated CO(2) is quantitatively reduced over a period of minutes to give the bis(oxo)-bridged dimer 2 and the dicarbonyl complex 3. In situ NMR studies indicated that this decomposition proceeds in a stepwise process via monooxo (5) and monocarbonyl (7) double-sandwich complexes, which have been independently synthesized and structurally characterized. 5 is thermally unstable with respect to a μ-O dimer in which the Ti–Ti bond has been cleaved and one pentalene ligand binds in an η(8) fashion to each of the formally Ti(III) centers. The molecular structure of 7 shows a “side-on” bound carbonyl ligand. Bonding of the double-sandwich species Ti(2)Pn(2) (Pn = C(8)H(6)) to other fragments has been investigated by density functional theory calculations and fragment analysis, providing insight into the CO(2) reaction pathway consistent with the experimentally observed intermediates. A key step in the proposed mechanism is disproportionation of a mono(oxo) di-Ti(III) species to yield di-Ti(II) and di-Ti(IV) products. 1 forms a structurally characterized, thermally stable CS(2) adduct 8 that shows symmetrical binding to the Ti(2) unit and supports the formulation of 4. The reaction of 1 with COS forms a thermally unstable complex 9 that undergoes scission to give mono(μ-S) mono(CO) species 10. Ph(3)PS is an effective sulfur transfer agent for 1, enabling the synthesis of mono(μ-S) complex 11 with a double-sandwich structure and bis(μ-S) dimer 12 in which the Ti–Ti bond has been cleaved

Identifying the sources driving observed PM2.5 temporal variability over Halifax, Nova Scotia, during BORTAS-B

The source attribution of observed variability of total PM_2.5 concentrations over Halifax, Nova Scotia was investigated between 11 July–26 August 2011 using measurements of PM_2.5 mass and PM_2.5 chemical composition (black carbon, organic matter, anions, cations and 33 elements). This was part of the BORTAS-B (quantifying the impact of BOReal forest fires on Tropospheric oxidants using aircraft and satellites) experiment, which investigated the atmospheric chemistry and transport of seasonal boreal wild fire emissions over eastern Canada in 2011. The US EPA Positive Matrix Factorization (PMF) receptor model was used to determine the average mass (percentage) source contribution over the 45 days, which was estimated to be: Long-Range Transport (LRT) Pollution 1.75 μg m⁻³ (47%), LRT Pollution Marine Mixture 1.0 μg m⁻³ (27.9%), Vehicles 0.49 μg m⁻³ (13.2%), Fugitive Dust 0.23 μg m⁻³ (6.3%), Ship Emissions 0.13 μg m⁻³ (3.4%) and Refinery 0.081 μg m⁻³ (2.2%). The PMF model describes 87% of the observed variability in total PM_2.5 mass (bias = 0.17 and RSME = 1.5 μg m⁻³). The factor identifications are based on chemical markers, and they are supported by air mass back trajectory analysis and local wind direction. Biomass burning plumes, found by other surface and aircraft measurements, were not significant enough to be identified in this analysis. This paper presents the results of the PMF receptor modelling, providing valuable insight into the local and upwind sources impacting surface PM_2.5 in Halifax during the BORTAS-B mission