Biopesticide activity from drimanic compounds to control tomato pathogens

Indexación: Scopus.Tomato crops can be affected by several infectious diseases produced by bacteria, fungi, and oomycetes. Four phytopathogens are of special concern because of the major economic losses they generate worldwide in tomato production; Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato, causative agents behind two highly destructive diseases, bacterial canker and bacterial speck, respectively; fungus Fusarium oxysporum f. sp. lycopersici that causes Fusarium Wilt, which strongly affects tomato crops; and finally, Phytophthora spp., which affect both potato and tomato crops. Polygodial (1), drimenol (2), isonordrimenone (3), and nordrimenone (4) were studied against these four phytopathogenic microorganisms. Among them, compound 1, obtained from Drimys winteri Forst, and synthetic compound 4 are shown here to have potent activity. Most promisingly, the results showed that compounds 1 and 4 affect Clavibacter michiganensis growth at minimal inhibitory concentrations (MIC) values of 16 and 32 μg/mL, respectively, and high antimycotic activity against Fusarium oxysporum and Phytophthora spp. with MIC of 64 μg/mL. The results of the present study suggest novel treatment alternatives with drimane compounds against bacterial and fungal plant pathogens. © 2018 by the authors.https://www.mdpi.com/1420-3049/23/8/205

Surface rearrangement at complex adsorbate-substrate interfaces

On the basis of the information theory approach we propose a novel statistical scheme for analyzing the evolution of coupled adsorbate-substrate systems, in which the substrate undergoes the adsorbate-induced transformations. A relation between the substrate morphology and the adsorbate thermodynamic state is established. This allows one to estimate the surface structure in terms of incomplete experimental information and the one concerning the adsorbate thermodynamic response to the structural modifications.Comment: 5 pages, 3 figure

Lattice dielectric response of CdCu{3}Ti{4}O{12} and of CaCu{3}Ti{4}O{12} from first principles

Structural, vibrational, and lattice dielectric properties of CdCu{3}Ti{4}O{12} are studied using density-functional theory within the local spin-density approximation, and the results are compared with those computed previously for CaCu{3}Ti{4}O{12}. Replacing Ca with Cd is found to leave many calculated quantities largely unaltered, although significant differences do emerge in zone-center optical phonon frequencies and mode effective charges. The computed phonon frequencies of CdCu{3}Ti{4}O{12} are found to be in excellent agreement with experiment, and the computed lattice contribution to the intrinsic static dielectric constant (~60) also agrees exceptionally well with a recent optical absorption experiment. These results provide further support for a picture in which the lattice dielectric response is essentially conventional, suggesting an extrinsic origin for the anomalous low-frequency dielectric response recently observed in both materials.Comment: 5 pages; uses REVTEX macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/lh_cdct/index.htm

Сіверські князі Наримунтовичі

У статті досліджується генеалогія та діяльність сіверських Наримунтовичів – однієї з гілок литовсько-руської династії Гедиміновичів, представники якої наприкінці XIV – початку XV ст. володіли кількома удільними князівствами у Сіверській землі.В статье исследуется генеалогия и деятельность северских Наримунтовичей – одной из ветвей литовско-русской династии Гедиминовичей, представители которой в конце XIV – начале XV вв. владели несколькими удельными княжествами в Северской земле.The article deals with genealogy and activity of the seversky Narimuntoviches as one of branches of the Lithuanian-Russian dynasty of the Gediminoviches, representatives of which at the end XIV – beginning of XV centuries owned some specific principalities in the Seversky land

Argon annealing of the oxygen-isotope exchanged manganite La_{0.8}Ca_{0.2}MnO_{3+y}

We have resolved a controversial issue concerning the oxygen-isotope shift of the ferromagnetic transition temperature T_{C} in the manganite La_{0.8}Ca_{0.2}MnO_{3+y}. We show that the giant oxygen-isotope shift of T_C observed in the normal oxygen-isotope exchanged samples is indeed intrinsic, while a much smaller shift observed in the argon annealed samples is an artifact. The argon annealing causes the 18O sample to partially exchange back to the 16O isotope due to a small 16O contamination in the Ar gas. Such a contamination is commonly caused by the oxygen outgas that is trapped in the tubes, connectors and valves. The present results thus umambiguously demonstrate that the observed large oxygen isotope effect is an intrinsic property of manganites, and places an important constraint on the basic physics of these materials.Comment: 4 pages, 3 figures, submitted to PR

Cooling rate dependence of the antiferromagnetic domain structure of a single crystalline charge ordered manganite

The low temperature phase of single crystals of Nd$_{0.5}$Ca$_{0.5}$MnO$_3$ and Gd$_{0.5}$Ca$_{0.5}$MnO$_3$ manganites is investigated by squid magnetometry. Nd$_{0.5}$Ca$_{0.5}$MnO$_3$ undergoes a charge-ordering transition at $T_{CO}$=245K, and a long range CE-type antiferromagnetic state is established at $T_N$=145K. The dc-magnetization shows a cooling rate dependence below $T_N$, associated with a weak spontaneous moment. The associated excess magnetization is related to uncompensated spins in the CE-type antiferromagnetic structure, and to the presence in this state of fully orbital ordered regions separated by orbital domain walls. The observed cooling rate dependence is interpreted to be a consequence of the rearrangement of the orbital domain state induced by the large structural changes occurring upon cooling.Comment: REVTeX4; 7 pages, 4 figures. Revised 2001/12/0

Quantitative ultrasound texture analysis of fetal lungs to predict neonatal respiratory morbidity

Objective To develop and evaluate the performance of a novel method for predicting neonatal respiratory morbidity based on quantitative analysis of the fetal lung by ultrasound. Methods More than 13¿000 non-clinical images and 900 fetal lung images were used to develop a computerized method based on texture analysis and machine learning algorithms, trained to predict neonatal respiratory morbidity risk on fetal lung ultrasound images. The method, termed ‘quantitative ultrasound fetal lung maturity analysis’ (quantusFLM™), was then validated blindly in 144 neonates, delivered at 28¿+¿0 to 39¿+¿0¿weeks' gestation. Lung ultrasound images in DICOM format were obtained within 48¿h of delivery and the ability of the software to predict neonatal respiratory morbidity, defined as either respiratory distress syndrome or transient tachypnea of the newborn, was determined. Results Mean (SD) gestational age at delivery was 36¿+¿1 (3¿+¿3) weeks. Among the 144 neonates, there were 29 (20.1%) cases of neonatal respiratory morbidity. Quantitative texture analysis predicted neonatal respiratory morbidity with a sensitivity, specificity, positive predictive value and negative predictive value of 86.2%, 87.0%, 62.5% and 96.2%, respectively. Conclusions Quantitative ultrasound fetal lung maturity analysis predicted neonatal respiratory morbidity with an accuracy comparable to that of current tests using amniotic fluid.Peer ReviewedPostprint (published version

Colossal magnetooptical conductivity in doped manganites

We show that the current carrier density collapse in doped manganites, which results from bipolaron formation in the paramagnetic phase, leads to a colossal change of the optical conductivity in an external magnetic field at temperatures close to the ferromagnetic transition. As with the colossal magnetoresistance (CMR) itself, the corresponding magnetooptical effect is explained by the dissociation of localized bipolarons into mobile polarons owing to the exchange interaction with the localized Mn spins in the ferromagnetic phase. The effect is positive at low frequencies and negative in the high-frequency region. The present results agree with available experimental observations.Comment: 4 pages, REVTeX 3.0, two eps-figures included in the tex

The BIOMEX experiment on-board the International Space Station: limits of life and detection of biomarkers after exposure to space- and to Mars-like conditions

To explore the limits of terrestrial life in space, we have to understand the effects of the space environment on unprotected biological and chemical material, and on the degradation of organic molecules or biomarkers. The exposure platform EXPOSE-R2 on the ISS offer a suitable facility for the exposure of samples of the astrobiological model lichen Circinaria gyrosa, included in the BIOMEX experiment (Biology and Mars Experiment, ESA). During 18 months (2014-2016), the lichens lived in a latent state at space and at simulated Mars-like conditions, to study Mars’ habitability and resistance to space conditions. After the return of the samples in June 2016, initial analysis showed rapid recovery of photosystem II (PSII) activity in the samples exposed exclusively to space vacuum and to Mars-like atmosphere. In contrast, the samples directly exposed to solar UV radiation showed a slow and a lower recovery, in reference to their observed original activity. This tendency was corroborated with the complementary morphological/ultrastructural and biomolecular analyses. Complementary, the biogeochemical variations have been examined with Raman spectroscopy to assess the possible degradation of cell surfaces and pigments which were in contact with terrestrial rocks, and Martian analogue regolith. Identification of the biomarker whewellite (calcium oxalate) and other organic compounds and mineral products of the biological activity of Circinaria gyrosa were detected by Raman Laser. These findings contribute to answer questions on the habitability of Mars, the likelihood of the Lithopanspermia Hypothesis, the capability to detect biomolecules exposed to an extraterrestrial environment by life-detection instruments and will be of relevance for planetary protection issues

Bonding, Moment Formation, and Magnetic Interactions in Ca14MnBi11 and Ba14MnBi11

The ``14-1-11'' phase compounds based on magnetic Mn ions and typified by Ca14MnBi11 and Ba14MnBi11 show unusual magnetic behavior, but the large number (104) of atoms in the primitive cell has precluded any previous full electronic structure study. Using an efficient, local orbital based method within the local spin density approximation to study the electronic structure, we find a gap between a bonding valence band complex and an antibonding conduction band continuum. The bonding bands lack one electron per formula unit of being filled, making them low carrier density p-type metals. The hole resides in the MnBi4 tetrahedral unit and partially compensates the high spin d^5 Mn moment, leaving a net spin near 4 \mu_B that is consistent with experiment. These manganites are composed of two disjoint but interpenetrating `jungle gym' networks of spin 4/2 MnBi4^{9-} units with ferromagnetic interactions within the same network, and weaker couplings between the networks whose sign and magnitude is sensitive to materials parameters. Ca14MnBi11 is calculated to be ferromagnetic as observed, while for Ba14MnBi11 (which is antiferromagnetic) the ferro- and antiferromagnetic states are calculated to be essentially degenerate. The band structure of the ferromagnetic states is very close to half metallic.Comment: 17 pages, containing 10 postscript figures and 5 tables. Two additional figures (Fig.8 and 11 of the paper) are provided in JPG format in separate files. Submitted to Phys. Rev. B on September 20th 200