Temperature-dependent Raman scattering of KTa1-xNbxO3 thin films

We report a Raman scattering investigation of KTa1-xNbxO3 (x = 0.35, 0.5) thin films deposited on MgO and LaAlO3 as a function of temperature. The observed phase sequence in the range from 90 K to 720 K is similar to the structural phase transitions of the end-member material KNbO3. Although similar in the phase sequence, the actual temperatures observed for phase transition temperatures are significantly different from those observed in the literature for bulk samples. Namely, the tetragonal (ferroelectric) to cubic (paraelectric) phase transition is up to 50 K higher in the films when compared to bulk samples. This enhanced ferroelectricity is attributed to biaxial strain in the investigated thin films

Observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films

High quality epitaxial thin films of Gd0.67Ca0.33MnO3 have been deposited onto (100) SrTiO3 substrates by pulsed-laser deposition. Enhanced properties in comparison with bulk samples were observed. The magnetic transition temperature (Tc) of the as-grown films is much higher than the corresponding bulk values. Most interestingly, magnetization measurements performed under small applied fields, exhibit magnetization reversals below Tc, no matter whether the film is field-cooled (FC) or zero-field-cooled (ZFC). A rapid magnetization reversal occurs at 7 K when field cooled, while as for the ZFC process the magnetization decreases gradually with increasing temperatures, taking negative values above 7 K and changing to positive values again, above 83 K. In higher magnetic fields the magnetization does not change sign. The reversal mechanism is discussed in terms of a negative exchange f-d interaction and magnetic anisotropy, this later enhanced by strain effects induced by the lattice mismatch between the film and the substrate.Comment: 16 pages, 4 figure

Influence of some factors on autolysis of Oenococcus oeni

Oenococcus oeni was able to autolyse after transfer to water at 40 degreesC. Cells harvested in the mid-log phase autolyse more rapidly than in other growth phases. Optimum conditions of pH (broad scale,vith two maxima at 4.0 and 7.0) and temperature (40 degreesC) have also been elucidated. Trypsin and EDTA appeared to enhance cell wall autolysis. The activity of several enzymes, namely an amidase or endopeptidase and a N-acetyl-β-D-glucosaminidase, were shown to be involved in the autolytic process, thereby releasing soluble cell wall fragments and nitrogen compounds

Floral vascular patterns of the double-flowered and wild-type morphs of Nigella damascena L. (Ranunculaceae)

The perianth of the double-flowered morph of Nigella damascena L. consists of spirally inserted petaloid sepals and sepal-like organs, similar in shape and colour to the petaloid sepals of the wild-type flower. It is devoid of petals. We compare the vascularization of each organ category of the double flower with that of the wild-type. We show that the vascular patterns of the sepal-like organs and of the petals are identical, and found an inverse relationship between the number of bracts and the number of sepals in the double-flowered morph. These two surprising findings will influence the future evo-devo studies on this plant model

Predominant mycotoxins, mycotoxigenic fungi and climate change related to wine

Wine is a significant contributor to the economies of many countries. However, the commodity can become contaminated with mycotoxins produced by certain fungi. Most information on mycotoxins in wine is from Spain, Italy and France. Grapes can be infected by mycotoxigenic fungi, of which Aspergillus carbonarius producing ochratoxin A (OTA) is of highest concern. Climate is the most important factor in determining contamination once the fungi are established, with high temperatures being a major factor for OTA contamination: OTA in wine is at higher concentrations in warmer southern Europe than northern. Contamination by fumonisins is a particular concern, related to Aspergillus niger producing these compounds and the fungus being isolated frequently from grapes. Aflatoxins can be present in wine, but patulin is seldom detected. Alternaria mycotoxins (e.g. alternariol) have been frequently observed. There are indications that T-2 toxin may be common. Also, the combined effects of mycotoxins in wine require consideration. No other mycotoxins are currently of concern. Accurate fungal identifications and mycotoxin detection from the fungi are important and a consideration of practical methods are required. There is a diversity of wines that can be contaminated (e.g. red, white, sweet, dry and fortified). The occurrence of OTA is higher in red and sweet than white wines. Steps to control mycotoxins in wine involve good agriculture practices. The effect of climate change on vines and mycotoxins in wine needs urgent consideration by well-constructed modelling studies and expert interpretation of existing data. Reliable models of the effect of climate change on vines is a priority: the health of vines affects mycotoxin contamination. A modelling study of OTA in grapes at higher temperatures over 100 years is required. Progress has been made in reducing OTA in wine. The other mycotoxins require consideration and the effects of climate change will become crucial.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of the UID/BIO/04469/2013 unit, COMPETE 2020 (POCI-01-0145-FEDER006684) and the BioTecNorte operation (NORTE-01-0145-FEDER000004). These were funded by the European Regional Development Fund through the Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Specific duplication and dorsoventrally asymmetric expression patterns of Cycloidea-like genes in zygomorphic species of Ranunculaceae.

Floral bilateral symmetry (zygomorphy) has evolved several times independently in angiosperms from radially symmetrical (actinomorphic) ancestral states. Homologs of the Antirrhinum majus Cycloidea gene (Cyc) have been shown to control floral symmetry in diverse groups in core eudicots. In the basal eudicot family Ranunculaceae, there is a single evolutionary transition from actinomorphy to zygomorphy in the stem lineage of the tribe Delphinieae. We characterized Cyc homologs in 18 genera of Ranunculaceae, including the four genera of Delphinieae, in a sampling that represents the floral morphological diversity of this tribe, and reconstructed the evolutionary history of this gene family in Ranunculaceae. Within each of the two RanaCyL (Ranunculaceae Cycloidea-like) lineages previously identified, an additional duplication possibly predating the emergence of the Delphinieae was found, resulting in up to four gene copies in zygomorphic species. Expression analyses indicate that the RanaCyL paralogs are expressed early in floral buds and that the duration of their expression varies between species and paralog class. At most one RanaCyL paralog was expressed during the late stages of floral development in the actinomorphic species studied whereas all paralogs from the zygomorphic species were expressed, composing a species-specific identity code for perianth organs. The contrasted asymmetric patterns of expression observed in the two zygomorphic species is discussed in relation to their distinct perianth architecture

Youngsters do not pay attention to conversational rules: is this so for nonhuman primates?

The potentiality to find precursors of human language in nonhuman primates is questioned because of differences related to the genetic determinism of human and nonhuman primate acoustic structures. Limiting the debate to production and acoustic plasticity might have led to underestimating parallels between human and nonhuman primates. Adult-young differences concerning vocal usage have been reported in various primate species. A key feature of language is the ability to converse, respecting turn-taking rules. Turn-taking structures some nonhuman primates' adult vocal exchanges, but the development and the cognitive relevancy of this rule have never been investigated in monkeys. Our observations of Campbell's monkeys' spontaneous vocal utterances revealed that juveniles broke the turn-taking rule more often than did experienced adults. Only adults displayed different levels of interest when hearing playbacks of vocal exchanges respecting or not the turn-taking rule. This study strengthens parallels between human conversations and nonhuman primate vocal exchanges

Incidence d'une activité glucanasique exogène sur le devenir des macromolécules levuriennes du vin

L'addition d'une preparation enzymatique contenant des activités pectinasiques et β (1→ + 3) glucanasiques sur les lies levuriennes est testée en rnilieu vin et en milieu synthétique. Son intérêt est double: hydrolysedes macromolécules présentes initialement dans le milieu et accéleration de la désorganisation du réseau glucanes de la paroi levurienne. Ceci se traduit par une augmentation de la libération de mannoprotéines d'environ 50 kDa.Influence of exogenous glucanase activity on the yeast macromolecules in wineThe addition of an enzymatic preparation containing pectinase and beta (1 --> 3) glucanase activities on yeast lees was tested in wine and a synthetic medium. We observed the hydrolysis of the macromolecules which were present initially in the medium and an acceleration of hydrolysis of cell wall glucans. The liberation of mannoproteins about 50 kDa was increased

Contribution à l'étude de la dégradation de l'acide L-malique par les bactéries lactiques isolées du vin: Effet stimulant des autolysats de levures

Degradation of L-malic acid by lactic bacteria isolated from wine:Stimulating effect of yeast autolysatesFive yeast autolysates used in the present study showed very different levels of proteolysis. They had a major effect on the growth and the malolactic activity of four strains of lactic acid bacteria isolated from wine (Lactobacillus hilgardii, Leuconostoc mesenteroi'des, Leuconostoc oenos strain 44-40 and Leuconostoc oenos strain B). This effect was always stimulating, but there was considerable interaction between the type of autolysate and the bacterial strain on the one hand and the composition of the culture medium (pH, ethanol) on the other hand