Interplay between adsorbates and polarons: CO on rutile TiO2_2(110)

Polaron formation plays a major role in determining the structural, electrical and chemical properties of ionic crystals. Using a combination of first principles calculations and scanning tunneling microscpoy/atomic force microscopy (STM/AFM), we analyze the interaction of polarons with CO molecules adsorbed on the rutile TiO$_2$(110) surface. Adsorbed CO shows attractive coupling with polarons in the surface layer, and repulsive interaction with polarons in the subsurface layer. As a result, CO adsorption depends on the reduction state of the sample. For slightly reduced surfaces, many adsorption configurations with comparable adsorption energies exist and polarons reside in the subsurface layer. At strongly reduced surfaces, two adsorption configurations dominante: either inside an oxygen vacancy, or at surface Ti$_{5c}$ sites, coupled with a surface polaron

Genetička varijabilnost prinosa i komponenti prinosa sjemena autohtonih populacija Lolium perenne L.

The aim of this study was to examine genetic variability, heritability and correlation of seed yield components and seed yield of progenies of autochthonous populations and cultivars of perennial ryegrass, and that on the basis of these results distinguish genotypes that would be later used in the creation of new local cultivars of perennial ryegrass. Research was carried out on experimental fields and laboratories of the Agricultural Institute of Republic of Srpska in Banja Luka in 2007. and 2008., on 6 natural populations of perennial ryegrass collected in Bosnia and Herzegovina and two cultivars, Maja and Calibra as standard. Following parameters were analyzed: number of generative tillers per plant, time of flowering, spike length, number of spikelets per spike, seed yield per spike and plant and 1000 seed weight. Analysis of the results of the number of generative tillers per plant indicates a statistically significant difference in the studied populations and cultivars of perennial ryegrass. The highest average number of tillers per plant was found in the cultivar Maja (193.8), and the least number was detected in population Dragočaj (78.9), so statistical differences were highly significant. The longest period to beginning of flowering was determined in cultivar Calibra (56.5 days) and the shortest in population Laminci (43 days). The average length of spike of perennial ryegrass in the studied population was 22.78 cm and was significantly lower than cultivar Maja. Statistically significant differences between populations and variety Maja in the number of spikelets per spike were detected. The average seed yield per spike of studied populations was in level with cultivar Maja and 37.5% higher compared with variety Calibra. In the studied populations of perennial ryegrass seed yield ranged from 5.21 g (Dragočaj population) to 15.40 g (Kupres population). Weight of 1000 seeds was highest in the variety Calibra (2.60 g) and lowest in population Maglajani (1.94 g). Proportion of genetic to phenotypic variance for time of flowering, the number of generative tillers, seed yield per spike and plant and 1000 seed weight indicate that the variability of these traits in this collection of genotypes, largely derived from plant genotype. In this investigation, the presence of a highly significant positive genetic correlation was found between time of flowering and spike length (0.98), time of flowering and 1000 seed weight (0.97), number of generative tillers and seed yield per plant (0.91) and spike length and 1000 seed weight (0.98).Cilj ovog rada je da se ispitaju genetička varijabilnost, heritabilnost i korelacije komponenti prinosa i prinos sjemena potomstava autohtonih populacija i sorti engleskog ljulja. Istraživanja su obavljena na oglednom polju i u laboratorijama Poljoprivrednog instituta Republike Srpske, tokom 2007. i 2008. godine. Proučavano je 6 autohtonih populacija engleskog ljulja sakupljenih u Bosni i Hercegovini i dvije sorte Maja i Calibra kao standardi. Analizirane su sledeće osobine: broj generativnih stabljika po biljci, broj dana do početka cvjetanja, dužina klasa, broj klasića po klasu, prinos sjemena po klasu i biljci i masa 1.000 sjemena. Analiza rezultata broja generativnih stabljika po biljci ukazuje da postoji visoko signifikantna razlika kod ispitivanih populacija i sorti engleskog ljulja. Najduži period do početka cvjetanja imala je sorta Calibra, a najkraći populacija Laminci. Prosječna dužina klasa kod ispitivanih populacija iznosila je 22,7 cm i bila je značajno manja u odnosu na sortu Maja.U broju klasića po jednom klasu postoje visoko signifikantne razlike između pojedinih populacija engleskog ljulja i sorte Maja. Prosječan prinos sjemena po klasu ispitivanih populacija bio je u nivou sorte Maja, a u odnosu na sortu Calibra viši za 37,5%. Kod ispitivanih populacija engleskog ljulja prinos sjemena bio je od 5,21 g (populacija Dragočaj) do 15,40 g (populacija Kupres). Masa 1.000 sjemena bila je najveća kod sorte Calibra. Tokom ispitivanja utvrđeno je postojanje visoko značajne pozitivne genetičke korelacije između početka cvjetanja i dužine klasa, početka cvjetanja i mase 1.000 sjemena, broja generativnih izdanaka i prinosa sjemena po biljci i dužine klasa i mase 1.000 sjemena

Automated Real-Space Lattice Extraction for Atomic Force Microscopy Images

Analyzing atomically resolved images is a time-consuming process requiring solid experience and substantial human intervention. In addition, the acquired images contain a large amount of information such as crystal structure, presence and distribution of defects, and formation of domains, which need to be resolved to understand a material's surface structure. Therefore, machine learning techniques have been applied in scanning probe and electron microscopies during the last years, aiming for automatized and efficient image analysis. This work introduces a free and open source tool (AiSurf: Automated Identification of Surface Images) developed to inspect atomically resolved images via Scale-Invariant Feature Transform (SIFT) and Clustering Algorithms (CA). AiSurf extracts primitive lattice vectors, unit cells, and structural distortions from the original image, with no pre-assumption on the lattice and minimal user intervention. The method is applied to various atomically resolved non-contact atomic force microscopy (AFM) images of selected surfaces with different levels of complexity: anatase TiO2(101), oxygen deficient rutile TiO2(110) with and without CO adsorbates, SrTiO3(001) with Sr vacancies and graphene with C vacancies. The code delivers excellent results and has proved to be robust against atom misclassification and noise, thereby facilitating the interpretation scanning probe microscopy images

Surface chemistry on a polarizable surface: Coupling of CO with KTaO3(001)

Polarizable materials attract attention in catalysis because they have a free parameter for tuning chemical reactivity. Their surfaces entangle the dielectric polarization with surface polarity, excess charge, and orbital hybridization. How this affects individual adsorbed molecules is shown for the incipient ferroelectric perovskite KTaO3. This intrinsically polar material cleaves along (001) into KO- and TaO2-terminated surface domains. At TaO2 terraces, the polarity-compensating excess electrons form a two-dimensional electron gas and can also localize by coupling to ferroelectric distortions. TaO2 terraces host two distinct types of CO molecules, adsorbed at equivalent lattice sites but charged differently as seen in atomic force microscopy/scanning tunneling microscopy. Temperature-programmed desorption shows substantially stronger binding of the charged CO; in density functional theory calculations, the excess charge favors a bipolaronic configuration coupled to the CO. These results pinpoint how adsorption states couple to ferroelectric polarization

Water Structures Reveal Local Hydrophobicity on the In2O3(111) Surface

Clean oxide surfaces are generally hydrophilic. Water molecules anchor at undercoordinated surface metal atoms that act as Lewis-acid sites, and they are stabilized by H bonds to undercoordinated surface oxygens. The large unit cell of In2O3(111) provides surface atoms in various configurations, which leads to chemical heterogeneity and a local deviation from this general rule. Experiments (TPD, XPS, ncAFM) agree quantitatively with DFT calculations and show a series of distinct phases. The first three water molecules dissociate at one specific area of the unit cell and desorb above room temperature. The next three adsorb as molecules in the adjacent region. Three more water molecules rearrange this structure and an additional nine pile up above the OH groups. Despite offering undercoordinated In and O sites, the rest of the unit cell is unfavorable for adsorption and remains water-free. The first water layer thus shows ordering into nanoscopic 3D water clusters separated by hydrophobic pockets

Occurrence of Deoxynivalenol in Maize and Wheat in Serbia

A total of 226 samples of maize and 59 of wheat from the 2004–2007 harvests were investigated for the presence and concentration of deoxynivalenol (DON). Samples of the 2004 harvest were analyzed after their storing for one year in barns, while those of the 2005–2007 harvest were taken directly off fields immediately after the harvest. The samples were analyzed by liquid chromatography on an ODS Hypersil column with DAD detector and ELISA methods. The average incidence rate of DON in maize from the 2004 harvest was 50% (concentration range 0.042–2.460 mg/kg, average value 0.536 mg/kg), while for those of the 2005–2007 harvest it was 32.4% (concentration range 0.027–2.210 mg/kg, average value 0.223 mg/kg). In the case of wheat incidence rate of DON for 2004 harvest was 50.0% (concentration range 0.630–1.840 mg/kg, average value 1.235 mg/kg), while for those of the 2005–2007 harvest it was 34.5% (concentration range 0.057–0.423 mg/kg, average value 0.190 mg/kg). Concentrations in two samples of maize and one of wheat (one sample of each cereal being of the 2004 harvest) were above the maximum level adopted by the European Commission. The results obtained were analyzed as a function of climatic conditions and compared with those of the neighboring countries where the relevant data existed

Soil phauna (Archaeognatha Zygentoma) insessile oak and beech forests

Fauna tla (Archaeognatha Zygentoma) kitnjakovih i bukovih šumaTematika završnog rada bavi se problemom neistraženosti poveznice redova kukaca Archaeognatha i Zygentoma i dendrološke komponente njihovih staništa, konkretno obične bukve (Fagus sylvatica) i hrasta kitnjaka (Quercus petraea)

Soil phauna (Archaeognatha Zygentoma) insessile oak and beech forests

Fauna tla (Archaeognatha Zygentoma) kitnjakovih i bukovih šumaTematika završnog rada bavi se problemom neistraženosti poveznice redova kukaca Archaeognatha i Zygentoma i dendrološke komponente njihovih staništa, konkretno obične bukve (Fagus sylvatica) i hrasta kitnjaka (Quercus petraea)

Assessment of the efficiency of modified flight barrier traps on the catches of flying buprestid beetles (Coleoptera, Buprestidae, Agrillinae)

U kontekstu prijetnje od dolaska novog invazivnog krasnika, štetnika jasena (Agrillus planipennis), u čistim i mješovitim sastojinama jasena testirana je učinkovitost modificiranih naletno barijernih klopki (promjena boje i visine montaže). Ovim prvim ciljanim testiranjem učinkovitosti ulova krasnika naletno barijernim klopkama željelo se istražiti mogućnost monitoringa krasnika općenito, a naročito u cilju rane detekcije eventualnih karantenskih štetnika