52 research outputs found
Cytospora friesii and Sydowia polyspora are associated with the sudden dieback of Abies concolor in Southern Europe
Abies concolor was introduced to Europe in the 19th century and commonly planted as an ornamental tree. In 2018, after several very warm and dry vegetation seasons, which has likely caused abiotic stress in the trees, a sudden dieback of A. concolor was observed in the city of Arandelovac in Serbia. The external symptoms were the rapid discoloration of needles in a larger part of the crown and eventually the dieback of the trees. The aim of this study was to identify the possible agents of damage by analysing the fungal communities associated with symptomatic needles using high-throughput sequencing as no symptoms of damage were seen on the branches or stems. Symptomatic needles were collected from the lower branches of five standing trees. Half of the needles were surface sterilised and the remaining were left unsterilised. DNA was extracted, amplified using ITS2 rDNA as a marker and sequenced. Quality filtering showed the presence of 6 191 high quality reads, which, following a clustering analysis, was found to represent 79 non-singletons fungal taxa. The most common fungi in both surface sterilised and unsterilised needles were the pathogens Cytospora friesii (59.7%) and Sydowia polyspora (20.6%). The results demonstrated that C. friesii and S. polyspora can cause a rapid decline of A. concolor trees subjected to abiotic stress
Fungal Diversity in the Phyllosphere of Pinus heldreichii H. Christ-An Endemic and High-Altitude Pine of the Mediterranean Region
Pinus heldreichii is a high-altitude coniferous tree species naturaly occurring in small and disjuncted populations in the Balkans and southern Italy. The aim of this study was to assess diversity and composition of fungal communities in living needles of P. heldreichii specifically focusing on fungal pathogens. Sampling was carried out at six different sites in Montenegro, where 2-4 year-old living needles of P. heldreichii were collected. Following DNA isolation, it was amplified using ITS2 rDNA as a marker and subjected to high-throughput sequencing. Sequencing resulted in 31,831 high quality reads, which after assembly were found to represent 375 fungal taxa. The detected fungi were 295 (78.7%) Ascomycota, 79 (21.0%) Basidiomycota and 1 (0.2%) Mortierellomycotina. The most common fungi were Lophodermium pinastri (12.5% of all high-quality sequences), L. conigenum (10.9%), Sydowia polyspora (8.8%), Cyclaneusma niveum (5.5%), Unidentified sp. 2814_1 (5.4%) and Phaeosphaeria punctiformis (4.4%). The community composition varied among different sites, but in this respect two sites at higher altitudes (harsh growing conditions) were separated from three sites at lower altitudes (milder growing conditions), suggesting that environmental conditions were among major determinants of fungal communities associated with needles of P. heldreichii. Trees on one study site were attacked by bark beetles, leading to discolouration and frequent dieback of needles, thereby strongly affecting the fungal community structure. Among all functional groups of fungi, pathogens appeared to be an important component of fungal communities in the phyllosphere of P. heldreichii, especially in those trees under strong abiotic and biotic stress
Patterns of fungal diversity in needles, rootlets and soil of endemic Pinus peuce
Pinus peuce is a five-needle pine native to high-elevation montane habitats of the Balkans. This study aimed to assess the diversity and composition of fungal communities associated with soil, rootlets and living needles of P. peuce at three high-altitude forest sites with different edaphic conditions and stand characteristics in south-eastern Montenegro. In total, 90 samples of each substrate (needles, rootlets and soil) were sampled. DNA amplification using ITS2 rDNA as a marker and high-throughput sequencing resulted in 23,394 high-quality reads, representing 825 fungal taxa. There were 52.5% Basidiomycota, 43.9% Ascomycota and 3.6% Mucoromycotina. There were 118 unique fungal taxa in the rootlets, 230 in soil and 113 in the needles, and only 8 taxa were shared. The most common fungi in rootlets were Rhizopogon mohelensis (11.0%), Suillus americanus (8.4%), and R. fallax (6.9%), in soil - Phlebiopsis gigantea (5.1%), Tylospora asterophora (2.9%), and Sollicocossima terricola (2.7%), and in the needles - Dothideomycetes sp. (17.6%), Dothideomycetes sp. (10.7%), and Leotiomycetes sp. (6.5%). The results showed that functional tissues and the rhizosphere soil of P. peuce were inhabited by a high diversity of fungi. Fungal communities in the rootlets and soil were largely determined by the site conditions such as soil properties and forest stand composition
CHARACTERIZATION OF BARIUM BISMUTH TITANATE OBTAINED BY MECHANOCHEMICAL SYNTHESIS
Barium bismuth titanate, BaBi4Ti4O15 (BBT) was prepared by homogenization and
sintering of mixture of stoichiometric quantities of BaTiO3 and Bi4Ti3O12 obtained via
mechanochemical synthesis. The reaction mechanism of BaBi4Ti4O15 formation and the
characteristics of BBT powders and ceramics were studied using XRD, Raman
spectroscopy and SEM. The results confirmed that BaBi4Ti4O15 was formed by
tetragonal symmetry. Only 4 Raman modes are clearly observed. Ba2+ ions randomly
occupy the Bi sites of a pseudo-perovskite layer and may enter in a bismuth oxide layer.
BaBi4Ti4O15 ceramics possess the plate-like structure typical for layered structure
materials
An overview of XR technologies usage for industrial robot programming
Industrial robot programming can be a challenging
task, especially in today's age, where robots are more widespread
outside the large manufacturing companies, but rather in small
and medium enterprises where users are not necessarily fully
qualified individuals. The Extended Reality technologies may be
the ongoing answer to improved robot programming experience.
Current solutions for robot programming using Extended Reality
technologies are explored in this overview. In this paper, a
summarized description of certain solutions is given, focusing on
how are the XR technologies utilized in developing the robot
programming systems. Categorization by devices and motion
planners used is also given
RAMAN STUDY OF FERROELECTRIC BARTUM BISMUTH TITANATE
Barium bismuth titanate, BaBi4Ti4O15 has been extensively studied for its feroelectric
and other excellent properties. BaBi4Ti4O15 is a candidate material for high temperature
piezoelectric applications, memory storage, and optical displays because of its high Curie
temperature and electro-optical properties. This family of bismuth oxides, discovered more
than 60 years ago by Aurivillius [1]. The structure of the Aurivillius family of compounds
consist of (Bi2O2)2+ layers interleaved with perovskite-like (An-1BnO3n+3)2- layers.
BaBi4Ti4O15 as the n = 4 member of the Aurivillius family has Ba ions at the I sites and Ti
ions at the .B sites of the perovskite (An-1BnO3n+3)2- block ((Bi2O2)2- .((BaBi4Ti4O15)2-) (Fig.
1). It has a high Curie temperature of 417 C [2]. The crystal structure of BaBi4Ti4O15 can
be described by an orthorhombic or a pseudotetragonal unit cell.
BaBi4Ti4O15 was prepared by homogenization and sintering of mixture of stoichiometric quantities
of barium titanate and bismuth titanate obtained via mechanochemical synthesis. Barium titanate, BaTiO3 has been synthesised from mixture of oxides BaO and TiO2 and bismuth titanate, Bi4Ti4O15 was prepared starting from mixture of Bi2O3 and TiO2, commercially available. The reaction mechanism of BaBi4Ti4O15 formation and the characteristics of BBT powders and ceramics were studied using XRD, Raman spectroscopy, particle size analysis and SEM.
The Bi-layered perovskite structure of BaBi4Ti4O15 forms by solid state reaction and sintering at 1100 C.
Microstructure of bismuth perovskite - layered materials exhibit plate-lit<e grains. The Ba2+ addition leads to the change in the microstructure development, particularly in the change of the average grain size.
The noticed mode at 160 cm-r is ascribed to the vibration of rigid-layer modes that are typical in these layered structures where a layer makes vibrations as a whole. The mode at 280 cm-1 arises from TiO6 octahedral vibrations and represents a combination made of bending-stretching
vibrations. The two modes of Bi4Ti4O15 around 537 cm-1 and 615 cm-1 change into a band in
Bi4Ti4O15 (A=Ba) around 558cm-1. This fact can be due to the line-broadening of the
two modes caused by the structural disorder in BaBi4Ti4O15 [3]. Hence this mode
corresponds to the vibration in a -pseudo-perovskite layer. Also, the mode at 880 cm-l,
whose frequency amounts 851 cm-1 in the case of a pure Bi4Ti4O15 compound, depends on
the sort of ions which are embedded in the lattice instead of Bi. The most probably, these
vibrations are closely related to the vibrations of the Ba-O bond
RAMAN STUDY OF FERROELECTRIC BISMUTH LAYER-OXIDE ABi4Ti4O15 PREPARED BY THE MECHANOCHEMICAL SYNTHESIS
Ferroelectric materials have innumerable properties related totheir spontaneus
polarization, for instance. pyre- and piezoelectricity, which are used for various sensors and
actuators il 1. BaBi4Ti4O12 (BBT) is an r : 4 member of the Bi-layer structured ferroelecrtric
oxide family (Auriviltius phase) [2]. Bi-layered structure ferroelectric material - bismuth
titanate, Bi+Ti:Orz (BIT) and barium-bismuth titanate, BaBi+Ti+Ors (BBT) ceramic powders
were prepared by mechanical synthesis possess. BaBi+TiaOrs was prepared from stoichometric quantities of barium titanate and bismuth titanate obtained via mechanochemical
synthesis. Barium titanate, BaTiOt has been synthesised from mixture of BaO and TiGz and
bismuth titanate, Bi+TirOr: was prepared starting from BiuO: and TiOz, comercialy
available. The reaction mechanism of BBT and the preparation and characteristics of BBT ceramic
powders u,ere studied using X-ray diffraction (XRD) and IR spectroscopy The
phonon modes have been studied by Rarran spectroscopy. The Bi-layered perovskite
structure of BBT cerantic fbrrns at ll00 "C. Microstructure of Bi+Ti:Or1 is in accordiance
with the vierv that Bi,rTilOr:exhibits plate-like grains with thr average grain size increasing
u,,ith the sintering temperature. lt is eviclent that Ba2- aclition leads to the change in the
microstructure development, particularly in the change of the average grain size an;
homogeneity of the grains of BaBi4Ti4O12
Carvacrol Derivatives as Antifungal Agents: Synthesis, Antimicrobial Activity and in Silico Studies on Carvacryl Esters
Chemical modifications of natural monoterpenoids to various derivatives have been reported to result in enhancement of biological activities when compared to parent compounds. In this context a well-known biocide and food additive, carvacrol, served as a basic scaffold onto which a phenolic functionality transformation by introducing acyl groups was performed. By using this simple methodology, we obtained a small series of 25 esters. For each of the obtained compounds we have performed structural characterization, in vitro antimicrobial testing and in silico calculation of physico-chemical, pharmacokinetic and toxicological properties. Despite numerous data on the synthesis and bioactivity of carvacryl ester lower homologues, there are scarce data on esters with acid components higher than C9, so that among 25 compounds, 10 were reported for the first time (spectral characterization for 12 are herein the first reported). Our research is also the first comprehensive study of carvacryl esters antifungal and of medium/long chain fatty acid esters antibacterial activities. Interesting result is that all the synthesized esters, regardless the nature of the R residue, have shown activity on fungal strain Aspergilus niger and on yeast Candida albicans comparable to carvacrol. Besides presented experimental data, implementation of in silico calculation of physico-chemical, pharmacokinetic and toxicological properties on the prepared compounds, may be valuable information in further research
The Serbian version of the Juvenile Arthritis Multidimensional Assessment Report (JAMAR)
The Juvenile Arthritis Multidimensional Assessment Report (JAMAR) is a new parent/patient-reported outcome measure that enables a thorough assessment of the disease status in children with juvenile idiopathic arthritis (JIA). We report the results of the cross-cultural adaptation and validation of the parent and patient versions of the JAMAR in the Serbian language. The reading comprehension of the questionnaire was tested in 10 JIA parents and patients. Each participating centre was asked to collect demographic, clinical data and the JAMAR in 100 consecutive JIA patients or all consecutive patients seen in a 6-month period and to administer the JAMAR to 100 healthy children and their parents. The statistical validation phase explored descriptive statistics and the psychometric issues of the JAMAR: the three Likert assumptions, floor/ceiling effects, internal consistency, Cronbach\u2019s alpha, interscale correlations, test\u2013retest reliability, and construct validity (convergent and discriminant validity). A total of 248 JIA patients (5.2% systemic, 44.3% oligoarticular, 23.8% RF-negative polyarthritis, 26.7% other categories) and 100 healthy children were enrolled in three centres. The JAMAR components discriminated healthy subjects from JIA patients. All JAMAR components revealed good psychometric performances. In conclusion, the Serbian version of the JAMAR is a valid tool for the assessment of children with JIA and is suitable for use both in routine clinical practice and clinical research
Worldwide diversity of endophytic fungi and insects associated with dormant tree twigs
International trade in plants and climate change are two of the main factors causing damaging tree pests (i.e. fungi and insects) to spread into new areas. To mitigate these risks, a large-scale assessment of tree-associated fungi and insects is needed. We present records of endophytic fungi and insects in twigs of 17 angiosperm and gymnosperm genera, from 51 locations in 32 countries worldwide. Endophytic fungi were characterized by high-throughput sequencing of 352 samples from 145 tree species in 28 countries. Insects were reared from 227 samples of 109 tree species in 18 countries and sorted into taxonomic orders and feeding guilds. Herbivorous insects were grouped into morphospecies and were identified using molecular and morphological approaches. This dataset reveals the diversity of tree-associated taxa, as it contains 12,721 fungal Amplicon Sequence Variants and 208 herbivorous insect morphospecies, sampled across broad geographic and climatic gradients and for many tree species. This dataset will facilitate applied and fundamental studies on the distribution of fungal endophytes and insects in trees
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