Field dependent anisotropy change in a supramolecular Mn(II)-[3x3] grid

The magnetic anisotropy of a novel Mn(II)-[3x3] grid complex was investigated by means of high-field torque magnetometry. Torque vs. field curves at low temperatures demonstrate a ground state with S > 0 and exhibit a torque step due to a field induced level-crossing at B* \approx 7.5 T, accompanied by an abrupt change of magnetic anisotropy from easy-axis to hard-axis type. These observations are discussed in terms of a spin Hamiltonian formalism.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

Regional microbial signatures positively correlate with differential wine phenotypes: evidence for a microbial aspect to terroir

Many crops display differential geographic phenotypes and sensorial signatures, encapsulated by the concept of terroir. The drivers behind these differences remain elusive, and the potential contribution of microbes has been ignored until recently. Significant genetic differentiation between microbial communities and populations from different geographic locations has been demonstrated, but crucially it has not been shown whether this correlates with differential agricultural phenotypes or not. Using wine as a model system, we utilize the regionally genetically differentiated population of Saccharomyces cerevisiae in New Zealand and objectively demonstrate that these populations differentially affect wine phenotype, which is driven by a complex mix of chemicals. These findings reveal the importance of microbial populations for the regional identity of wine, and potentially extend to other important agricultural commodities. Moreover, this suggests that long-term implementation of methods maintaining differential biodiversity may have tangible economic imperatives as well as being desirable in terms of employing agricultural practices that increase responsible environmental stewardship

Association between Grape Yeast Communities and the Vineyard Ecosystems

The grape yeast biota from several wine-producing areas, with distinct soil types and grapevine training systems, was assessed on five islands of Azores Archipelago, and differences in yeast communities composition associated with the geographic origin of the grapes were explored. Fifty-seven grape samples belonging to the Vitis vinifera grapevine cultivars Verdelho dos Acores (Verdelho), Arinto da Terceira (Arinto) and Terrantez do Pico (Terrantez) were collected in two consecutive years and 40 spontaneous fermentations were achieved. A total of 1710 yeast isolates were obtained from freshly crushed grapes and 1200 from final stage of fermentations. Twenty-eight species were identified, Hanseniaspura uvarum, Pichia terricola and Metschnikowia pulcherrima being the three most representative species isolated. Candida carpophila was encountered for the first time as an inhabitant of grape or wine-associated environments. In both sampling years, a higher proportion of H. uvarum in fresh grapes from Verdelho cultivar was observed, in comparison with Arinto cultivar. Qualitatively significant differences were found among yeast communities from several locations on five islands of the Archipelago, particularly in locations with distinctive agro-ecological compositions. Our results are in agreement with the statement that grape-associated microbial biogeography is non-randomly associated with interactions of climate, soil, cultivar, and vine training systems in vineyard ecosystems. Our observations strongly support a possible linkage between grape yeast and wine typicality, reinforcing the statement that different viti-cultural terroirs harbor distinctive yeast biota, in particular in vineyards with very distinctive environmental conditions.Joao Drumonde Neves is the recipient of a fellowship of the Azorean Government (M321/006/F/2008) and PROEMPREGO. This work was supported by the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalizacao (POCI), and by national funds through FCT by the projects FCOMP-01-0124-008775, PTDC/AGR-ALI/103392/2008 and PTDC/AGR-ALI/121062/2010.info:eu-repo/semantics/publishedVersio

Quantifying variation in the ability of yeasts to attract Drosophila melanogaster

Yeasts that invade and colonise fruit significantly enhance the volatile chemical diversity of this ecosystem. These modified bouquets are thought to be more attractive to Drosophila flies than the fruit alone, but the variance of attraction in natural yeast populations is uncharacterised. Here we investigate how a range of yeast isolates affect the attraction of female D. melanogaster to fruit in a simple two choice assay comparing yeast to sterile fruit. Of the 43 yeast isolates examined, 33 were attractive and seven repellent to the flies. The results of isolate-versus-isolate comparisons provided the same relative rankings. Attractiveness varied significantly by yeast, with the strongly fermenting Saccharomyces species generally being more attractive than the mostly respiring non-Saccharomyces species (P = 0.0035). Overall the habitat (fruit or other) from which the isolates were directly sampled did not explain attraction (P = 0.2352). However, yeasts isolated from fruit associated niches were more attractive than those from non-fruit associated niches (P = 0.0188) regardless of taxonomic positioning. These data suggest that while attractiveness is primarily correlated with phylogenetic status, the ability to attract Drosophila is a labile trait among yeasts that is potentially associated with those inhabiting fruit ecosystems. Preliminary analysis of the volatiles emitted by four yeast isolates in grape juice show the presence/absence of ethanol and acetic acid were not likely explanations for the observed variation in attraction. These data demonstrate variation among yeasts for their ability to attract Drosophila in a pattern that is consistent with the hypothesis that certain yeasts are manipulating fruit odours to mediate interactions with their Drosophila dispersal agent. © 2013 Palanca et al

Creating a regular array of metal-complexing molecules on an insulator surface at room temperature

Controlling self-assembled nanostructures on bulk insulators at room temperature is crucial towards the fabrication of future molecular devices, e.g., in the field of nanoelectronics, catalysis and sensor applications. However, at temperatures realistic for operation anchoring individual molecules on electrically insulating support surfaces remains a big challenge. Here, we present the formation of an ordered array of single anchored molecules, dimolybdenum tetraacetate, on the (10.4) plane of calcite (CaCO3). Based on our combined study of atomic force microscopy measurements and density functional theory calculations, we show that the molecules neither diffuse nor rotate at room temperature. The strong anchoring is explained by electrostatic interaction of an ideally size-matched molecule. Especially at high coverage, a hard-sphere repulsion of the molecules and the confinement at the calcite surface drives the molecules to form locally ordered arrays, which is conceptually different from attractive linkers as used in metal-organic frameworks. Our work demonstrates that tailoring the molecule-surface interaction opens up the possibility for anchoring individual metal complexing molecules into ordered arrays

Die geskiedenis van die Langkloof tot 1795

Thesis (MA) -- Stellenbosch University, 1994.ENGLISH ABSTRACT:Since the beginning ot the eighteenth century white cattle farmers passed regularly through the Langkloof. At the time they appeared on the scene native hunters and stock-farmers had already settled in the valley. By taking twenty farms on loan from the Dutch East India Colllpany the entire Langkloof was occupied by whites between the years 1760 to 1765. They were predominantly members d the second and third generation of the settlers who originally ca;ne to the Cape cl Good Hope. The community which evolved during the last four decades ot the eighteenth century in the Langkloof as a result or the influx cl whites, consisted of a small number of families. The majority oC these families were related to one another. Except for a few leading figures and persons notorious for their unconventional conduct, there were no other outstanding characters in the Langkloof. The first white inhabitants were pioneers who, living in isolation, had to struggle for survival. They were mainly stock-farmers, but as the result of the climate and vegetation, the large distances fn:Ma the market place, and the detrimental economic policy or the govern nent oC the Dutch East India Company, they could not prosper. Culturally they were deprived. There is only scanty evidence of formal education in the Langkloof, but the majority of white adults could at least sign their names. The only contact they had with the outside world was with expeditions travelling through the valley, and with the officials of the Company, especially those stationed at the drostdy at Swellendam. The churches closest to them, in Tulbagh and cape Town, were as a result of the distances, almost exclusively visited on occasions of baptism and weddings. During approximately the last two decades of the rule ot the Dutch East India Company, lite In the Langkloot gained an additional dimension as a result of the political turbulence surrounding the rebellion against the authorities at Swellendam, and the threat the Bantu east of the valley posed to the survival of the whites. Up to 1795 there were no significant dramatic happenings in the Langkloof. Without being in the centre of attention the community in the valley was developing an own unique identity.AFRIKAANSE OPSOMMING:Toe blanke veeboere die Langkloof vanaf die begin van die agtiende eeu op 'n gereelde basis begin betree het, was daar alreeds inheemse jagters en veeboere, naamlik die Khwe en Boesmans, woonagtig. Tussen 1760 en 1765 is die hele Langkloof' deur blankes beset deurdat twintig plase volgens die leningsplaasstelsel deur bJanke kolonfste, wat hoofsaaklik van die tweede en derde geslag van die Suid-Mrikaanse stamvaders was, bekom is. Die gemeenskap wat as gevolg daarvan gedurende die laaste vier dekades van die agtiende eeu in die Langkloof ontstaan bet, het uit 'n paar families bestaan wat, .aet weinige uitsonderings na, aan mekaar verwant was. Behalwe vir enkele leiersfigure en persone wat berugtheid weens hul robuuste optrede verwerf het, was daar nie ander uitstaande persoonlikhede nie. Die eerste blanke Langklowers was pioniers wat in omstandighede van isolasie 'n worstelstryd om oorlewing gevoer het. Die hoofbedryf was veeboerdery. maar faktore soos bodemgesteldheid, afstand van die markte en die wurgende ekonomiese beleid van die Kompanjiesregering bet die Langklowers ekonomles agterlik gehou. Op kulturele gebied was daar weinig beskawingsinvloede. Van formele opvoeding in die Langkloof kon weinig spore gevind word, maar daar is bewyse dat die meeste volwasse blanke inwoners ten minste kon skryf. Die enigste aanraking met die buitewereld was met die reisgeselskappe en die amptenary van die Kompanjie, veral van die drosdy op Swellendam. Met die naaste kerke in die Land van Waveren (Tulbagh) en Kaapstad, is 'n kerk byna uitsluitlik net met doop- en huweliksgeleenthede besoek. Vir ongeveer die laaste twee dekades van die V.O.C.-bewind bet die alledaagse lewe in die Langkloof 'n nuwe dlmensle bygekry as gevoll van die polltlek woellnge, aangestlg deur ontevredenheid met die owerhede, wat op 'n opstand teen die regeringsgesag op Swellendam uitgeloop het, en die bedrelglng wat die Bantu oos van die vallel vir die blankes se voortbestaan ingehou bet. Tot 1795 bet daar in die Langkloof geen groat dramatiese gebeurtenlsse plaasgevind nie. Die gemeenskap daar was besig om sander opspraak 'n eie unieke identiteit te ontwikkel