TEM and DFT Study of Basal-plane Inversion Boundaries in SnO2-doped ZnO

In our recent study (Ribie et al. 2020) we reported the structure of inversion boundaries (IBs) in Sb2O3 -doped ZnO. Here, we focus on IBs that form in SnO2-doped ZnO. Using atomic resolution scanning transmission electron microscopy (STEM) methods we confirm that in SnO2-doped ZnO the IBs form in head-to-head configuration, where ZnO4 tetrahedra in both ZnO domains point towards the IB plane composed of a close packed layer of octahedrally coordinated Sn and Zn atoms. The in-plane composition is driven by the local charge balance, following Pauling's principle of electroneutrality for ionic crystals, according to which the average oxidation state of cations is 3+. To satisfy this condition, the cation ratio in the IB-layer is Sn4+ : Zn2+ =1:1. This was confirmed by concentric electron probe analysis employing energy dispersive spectroscopy (EDS) showing that Sn atoms occupy 0.504 +/- 0.039 of the IB layer, while the rest of the octahedral sites are occupied by Zn. IBs in SnO2-doped ZnO occur in the lowest energy, IB3 translation state with the cation sublattice expansion of Delta IB(zn-zn) of +91 pm with corresponding O-sublattice contraction Delta IB(O-O) of -46 pm. Based on quantitative HRTEM and HAADF-STEM analysis of in-plane ordering of Sn and Zn atoms, we identified two types of short-range distributions, (i) zigzag and (ii) stripe. Our density functional theory (DFT) calculations showed that the energy difference between the two arrangements is small (similar to 6 meV) giving rise to their alternation within the octahedral IB layer. As a result, cation ordering intermittently changes its type and the direction to maximize intrinsic entropy of the IB layer driven by the in-plane electroneutrality and 6-fold symmetry restrictions. A long-range in-plane disorder, as shown by our work would enhance quantum well effect to phonon scattering, while Zn2+ located in the IB octahedral sites, would modify the the bandgap, and enhance the in-plane conductivity and concentration of carriers

New inversion boundary structure in Sb-doped ZnO predicted by DFT calculations and confirmed by experimental HRTEM

Today, ab-initio calculations are becoming a powerful tool to perform virtual experiments that have the capacity to predict and to reproduce experimentally observed non-periodic features, such as interfaces, that are responsible for quantum properties of materials. In our paper we investigate 2D quantum-well structures, known as inversion boundaries OM. Combining atomistic modeling, DFT calculations and HRTEM analysis we provide a new fundamental insight into the structure and stability of Sb-rich basal-plane IBs in ZnO. DFT screening for potential IB model was based on the known stacking deviations in originating wurtzite structure. The results show that the model with A beta-B alpha-A beta C-gamma B-beta C sequence (IB3) is the most stable translation for Sb-doping, as opposed to previously accepted A beta-B alpha-A beta C-gamma A-alpha C (IB2) model. The key to the stability of IB structures has been found to lie in their cationic stacking. We show that the energies of constituting stacking segments can be used to predict the stability of new IB structures without the need of further ab-initio calculations. DFT optimized models of IBs accurately predict the experimentally observed IB structures with lateral relaxations down to a precision of similar to 1 pm. The newly determined cation sublattice expansions for experimentally confirmed IB2 and IB3 models, Delta(IB(zn-zn)) are +81 pm and +77 pm, whereas the corresponding O-sublattice contractions Delta(IB(0-0)) are -53 pm and -57 pm, respectively. The refined structures will help to solve open questions related to their role in electron transport, phonon scattering, p-type conductivity, affinity of dopants to generate IBs and the underlying formation mechanisms, whereas the excellent match between the calculations and experiment demonstrated in our study opens new perspectives for prediction of such properties from first principles

СИМУЛТАНА ПРОЦЕНА ПРОСЕЧНОГ ПРИНОСА И СТАБИЛНОСТИ ХИБРИДА КУКУРУЗА КОРИШЋЕЊЕМ БИПЛОТА И КАНГОВОГ ПАРАМЕТРА YSI

Интегрисање процене просечног приноса и стабилности приноса хибрида кукуруза у јединствену анализу је значајно са практичног становиштаза признавање и препоруку сортимента на основу спроведених вишелокацијских огледа. Циљ истраживања је обухватао (и) утврђивање просечног приноса зрна и стабилности приноса за 21 еxпериментални хибрид кукуруза, коришћењем Канговог YSi параметра и GGE биплота, на основу вишелокацијских огледа постављених 2004 године у Србији; (ии) поређење резултата за просечни принос и стабилност приноса хибрида утврђенх искључивањем изнадпросечно-приносних и исподпросечно-приносних локалитета из целокупног сета коришћених локалитета; (иии) проверу утицаја линеарног ефекта индекса средине на стабилност приноса генотипова. Хетерогеност изазвана индексом средине (EI) је била статистистички незначајна за сва три проучавана сета локалитета. Неподударност је уочена у процени просечног приноса и стабилности приноса хибрида на основу GGE биплот анализе и Канговог YSi параметра за целокупан сет локалитета и за сет исподпросечно-приносних локалитета. Препоручејемо GGE биплот као информативнији и прецизнији начин за симултану процену просечног приноса и стабилности приноса генотипова

Nutritional properties of Macedonian landraces of small grain cereals as a source of new genetic variability

Taking into account the better agro-ecological adaptations developed over time to climate changed conditions, cereal local populations (landraces) represent a valuable plant genetic resources with their perspective reflected in the creation of better quality commercial cereal genotypes. The objectives of this research were to explore: i) the genetic variability of nutritional properties of Macedonian landraces of small grain cereals-wheat, barley, oat, and rye; ii) associations among nutritional properties; iii) strength and weakness of landraces based on nutritional properties profiles. Collecting missions were carried out in 2013 year in different locations of rural areas at the territory of Republic of Macedonia. Ten sub-samples of 100 g seeds were extracted from each of regenerated landrace in order to obtain a well-balanced analytical sample. All samples were analysed for moisture content - MOI (%), protein content - PC (%), fat content - FC (%), crude fibre content CF (%), wet gluten content - WG (%), and dry gluten content - DG (%). In regard to assessed nutritional properties the most perspective landraces proved to be: Okalesta bela (CF of (x) over bar = 2.62%) of bread wheat; Zimski (WG of (x) over bar= 9.24%), Dabilski nizok (DG of (x) over bar = 4.2%) and Ednoreden (CF of (x) over bar = 5.18%) of barley; Sopski (PC of (x) over bar= 14.62%), Gabarski (FC of (x) over bar = 6.46%) and Sekulicki (CF of (x) over bar = 9.89%) of oat; Calakliski (PC of (x) over bar = 14.43%, CF of (x) over bar = 8.16%), Koselski (FC of (x) over bar= 4.19%), and Gabarski (DG of (x) over bar = 3.14%) of rye. The positive associations among nutritional properties of Macedonian landraces of small grain cereals were: all examined nutritional properties except PC and CF in bread wheat landraces; PC, WG, DG, MOI as one cluster, and FC and CF as another cluster in barley landraces; all examined nutritional properties except MOI and CF in oat landraces; PC, CF, FC as one cluster and DG and MOI as another cluster in rye landraces. The Macedonian landraces of small grain cereals proved to be new sources of genetic variability of nutritional properties which can be used in breeding, because they outperformed commercial check cultivar landraces with statistical significance (P lt 0.05) for: MOI (4 landraces) and CF (4 landraces) for bread wheat; WG (Zimski), DG (3 landraces), CF (7 landraces) for barley; CF (5 landraces) for oat; DG (1 landrace), MOI (4 landraces), FC (4 landraces in rye)

Expected genetic advance and stability of phytic acid and antioxidants content in bread and durum wheat

Fifteen genotypes of bread wheat (Triticum aestivum L.) and fifteen genotypes of durum wheat (Triticum durum Desf.) were evaluated in the multi-environment trial during 2010-11. and 2011-12 vegetation seasons to investigate components of variance, heritability in a broad sense (h(2)), expected genetic advance (GA), and stability of phytic acid (PA), inorganic phosphorus (P-i), phytic phosphorus (P-p)/P-i relation, yellow pigment (YP), water soluble phenolics (WSPH) and free protein sulfhydryl groups (PSH) content. The field trials were carried out at three locations in Serbia, as randomized complete block design with four replications. The genetic component of variance (sigma(2)(g)) predominated the genotype x environment interaction (sigma(2)(ge)) component for: P-i in bread wheat (3.0 times higher), P-p/P-i in bread wheat (2.1 times higher) and in durum wheat (1.2 times higher), YP content in bread wheat (2.2 times higher) and in durum wheat (1.7 times higher), and WSPH content in bread wheat (1.4 times higher). The relation sigma(2)(g)/sigma(2)(ge) for P-i content in durum wheat was equal to one. The sigma(2)(ge) prevailed sigma(2)(g) for: PA in bread wheat (1.7 times higher) and in durum wheat (5.7 times higher), PSH in durum wheat (3.7 times higher), and WSPH in durum wheat (5.2 times higher). High h(2) coupled with high expected genetic advance as percent of mean (GAM) were observed for: P-i (93.7% and 26.1%, respectively) in bread wheat, P-p/P-i relation in bread wheat (92.4% and 20.7%, respectively) and in durum wheat (87.2% and 20.8%, respectively), YP content in bread wheat (92.6% and 28.0%, respectively) and in durum wheat (90.7% and 28.1%, respectively), and WSPH content (88.9% and 25.8%, respectively) in bread wheat. PA content in bread and durum wheat had medium to medium high h(2) (50.5% and 77.9%, respectively), and low expected GAM (9.9% and 3.7%, respectively). GGE biplots with average-environment coordination (AEC) indicated less stability of durum wheat for PA, WSPH and PSH content

Grain yield, agronomic traits, and protein content of two- and six-row barley genotypes under terminal drought conditions

Small grain cereals in lower latitude areas usually mature under terminal drought conditions that affect their agronomic performance. An experiment was conducted to compare agronomic traits, grain yield, and protein content under control and terminal drought conditions of 15 two-row and 10 six-row barley (Hordeum vulgare L.) genotypes. The experiment was set up at two locations for two growing seasons (2011, 2012) and two treatments. One treatment was terminal drought (D) simulated by the mechanical removal of all leaf blades 7 d after the heading of each genotype, and a control (C) treatment in which plants were left intact. On average, defoliation caused a greater reduction in grain yield and protein content of the six-row genotypes (37.6% and 12.3%, respectively) than the two-row genotypes (28.8% and 7.1%, respectively). On the other hand, test weight of six-row genotypes showed better tolerance to terminal drought. According to the multivariate function analysis, the genotypes of both types of barley with a high test weight, a longer uppermost internode, and a longer grain filling period had high protein content under terminal drought stress. In contrast to six-row genotypes, it is possible to breed two-row genotypes that not only have high grain yield but also high protein content under both optimal and drought stress conditions

Tumor necrosis factor alpha and alpha-1 antitrypsin gene variants in Serbian pediatric arterial ischemic stroke patients

Etiologija arterijskog ishemijskog moždanog udara (AIS) kod dece je veoma kompleksna i razlikuje se od one kod odraslih. Iako je redak, moždani udar kod dece predstavlja značajan uzrok mortaliteta i morbiditeta. Sve je više podataka o ulozi genetičkih faktora, uključujući tu i medijatore inflamacije, u nastanku i ishodu moždanog udara. U ovoj studiji, odabrali smo da ispitamo ulogu polimorfizma -308G/A u genu za faktor nekroze tumora-alfa (eng. Tumor Necrosis Factor α -TNFα), kao i mutacija S i Z u genu za alfa1-antitripsin (AAT)u etiologiji moždanog udara kod dece. Polimorfizam -308G/A u genu za TNFα dovodi do povećanja koncentracije ovog proteina u plazmi, što bi moglo da doprinese patologiji moždanog udara. Pokazano je i da povišena koncentracija AAT može da predstavlja rizik za nastanak moždanog udara kod dece. S obzirom da mutacije S i Z u genu za AAT dovode do smanjenja koncentracije ovog proteina u plazmi, one bi mogle da imaju protektivnu ulogu kada je u pitanju moždani udar.Genske varijante TNFα (-308G/A) i AAT (S i Z) su ispitivane u grupi od 26 dece sa AIS i 100 odraslih osoba PCR/RFLP metodom.Nije nađena statistički značajna razlika u učestalosti -308G/A TNFα polimorfizma između pacijenata i kontrola, tako da u našoj grupi pacijenata TNFα najverovatnije nije imao značajnu ulogu u razvoju bolesti. Ni kod jednog pacijenta nije pronađena nijedna od ispitivanih mutacija u genu za AAT, što je bilo u skladu sa potencijalnom protektivnom ulogom ovih varijanti.AIS je multifaktorijalno oboljenje, u čijoj patologiji veliki broj gena ima -ulogu, tako da je potrebna dalja analiza zajedničkog delovanja većeg broja genskih varijanti da bi se rasvetlila njihova uloga kao genetičkih faktora rizika i njihovog uticaja na razvoj i ishod moždanog udara.The etiology of arterial ischemic stroke (AIS) in children is complex, and different from that in adults. Although rare, stroke in children is an important cause of mortality and morbidity. There is increasing evidence that genetic factors, including inflammation mediators, have a role in occurrence and outcome of stroke. We have chosen to assess the role of polymorphism -308G/A in the promoter of tumor necrosis factor α (TNFα) gene and S and Z mutations in alpha 1-antitrypsin (AAT) gene in the etiology of stroke in children. TNFα polymorphism affects plasma levels of this proinflamatory cytokine, and this could contribute to stroke pathology. It has been shown that increased AAT concentration may present a risk for AIS in children. Since S and Z mutations in AAT gene reduce its levels in plasma they could have a protective role in pediatric stroke. In this study twenty six children with AIS and 100 unrelated individuals from Serbian general population were investigated by PCR/RFLP for these gene variations. No statistically significant difference was observed between patients and general population in distribution of genotypes for -308G/A TNFα polymorphism, so its contributory role in the etiology of stroke was not evident in our group of patients. None of the tested AAT gene mutations were found in patients, which is in concordance with the proposed protective role of deficient AAT variants. AIS is a multifactorial disease, with many genes having a modest role in its pathophysiology, so further analyses of their combined effect are needed to elucidate genetic risk factors in the etiology and outcome of stroke in pediatric patients

Synthesis, characterization and photocatalytic properties of LaNiO3-based powders

Lanthanum nickelate (LaNiO3, LNO) belongs to the group of materials with perovskite-type structure and it crystallizes in rhombohedrally distorted perovskite lattice. This material exhibits interesting electrical, magnetic, optical and catalytic properties and it is suitable for various applications. Still, the preparation of single phase LNO is difficult, because at temperatures above 850 °C it decomposes into the lower oxides with formula Lan+1NinO3n+1 (n = 3, 2, 1) and NiO. In this work we present the synthesis of pure and Nb doped LNO powders, LaNi1-xNbxO3 (x = 0.000, 0.005, 0.010) prepared from mechanochemically activated oxide precursors – La2O3, NiO and Nb2O5. For this experiment, precursor powders homogenized in isopropyl alcohol were dried and mechanochemically activated in the planetary ball mill for 3 h. As-prepared powders were calcined at 700 °C for 3 h in air and further analyzed by X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM) and UV-Vis spectroscopy. Photocatalytic activity in visible light was investigated. The XRD analysis of undoped LNO revealed the existence of rhombohedral LaNiO3 and small amount of NiO phase. The doped samples, apart from LNO, contained products of thermal decomposition – layered oxides and NiO. TEM and HRTEM analyses of undoped LNO revealed the presence of agglomerated particles with single particle size being in the range of 20–40 nm. Doping with Nb led to decrease of agglomeration process and allowed better dispersion between particles of LNO based powders. Calculated band gaps were 1.12 eV, 0.89 eV and 0.87 eV for x = 0.00, 0.005, 0.010. The absorption spectra indicated photocatalytic degradation of Reactive Orange 16, textile dye used as a model in these experiments

Genetička analiza asocijacija agronomskih osobina i tehnološkog kvaliteta hlebne i durum pšenice

Влажни глутен (WG) је корелисан са садржајем протеина (PC), и представља уобичајену спецификацију квалитета брашна за крајње кориснике индустрије хране. Zeleny седиментација (ZS) је повезана са снагом глутена, пекарским квалитетом, запремином хлеба, али и са добрим квалитетом тестенине при кувању. Једна од најзначајнијих реолошких особина и индикатор на тржишту житарица је рад деформације (W) или снага теста, који мери деформацију теста, и показатељ је јачине брашна. Циљ овог истраживања је био да се примени GT анализа генотипова по особинама да би се утврдиле асоцијације између 10 агрономских особина и технолошког квалитета-PC, WG, ZS, W, као и могућност примене индиректне селекције код 30 генотипова хлебне и дурум пшенице. Пољски огледи су били посејани током две вегетационе сезоне 2010-2011. и 2011-2012. на три локалитета: Римски Шанчеви, Земун Поље и Падинска Скела. PC, WG, ZS, W су одређени применом НИР спектрометрије на анализатору Infraneo (Chopin Technologies, France). GT биплот је коришћен за визуализацију асоцијација агрономских особина и особина технолошког квалитета, као и за профиле особина генотипова. Принос зрна је био позитивно корелисан са ЗС, а негативно са PC, WG, W, код хлебне пшенице, док је код дурум пшенице показао негативну корелацију са све четири проучаване особине технолошког квалитета. С обзиром на постојање јаке позитивне асоцијације између дебљине зрна (GT) и ZS, и у мањој мери између GT и PC, GT и WG, GT и W, GT може бити подесна агрономска особина за индиректну селекцију у побољшању проучаваних карактеристика технолошког квалитета хлебне и дурум пшенице. Стаклавост зрна је била позитивно повезана са PC, и у мањем степену са WG, W, и ZS, и такође је представљала пожељну агрономску особину за индиректну селекцију у оплемењивању за бољи технолошки квалитет дурум пшенице у погледу проучаваних особина

Kako do prevencije rizičnih ponašanja učenika: vodič za primenu interaktivnog učenja u radioničarskom radu

Zdravstvena kriza izazvana pandemijom virusa COVID-19 pogodila je sve sfere društvenog funkcionisanja i izazvala transformaciju obrazovno-vaspitnog procesa širom sveta. Digitalizacija i fizička distanca obeležile su rad škola od početka pandemije i umnogome izazvale teškoće u sprovođenju obrazovno-vaspitnog rada, ali i donele nove izazove u radu na prevenciji rizičnih ponašanja učenika. Izmenjene okolnosti ocenjuju se kao značajan rizični faktor koji može nepovoljno uticati na uslove u kojima se deca razvijaju, uče, istražuju i ostvaruju svoje potencijale, te predstavlja pogodno tle za razvoj raznovrsnih rizičnih ponašanja. Pred školom se nalazi ozbiljan zadatak da se adaptira na novonastale okolnosti, na promene u ponašanju učenika, ali i da iznađe efektivne načine kontinuiranog rada na prevenciji u novoj realnosti. Tokom 2021. godine, realizovano je nacionalno kvantitativno istraživanje o potrebama škola u izmenjenim okolnostima obrazovno-vaspitnog rada, sa fokusom na perspektivu nastavnika, u organizaciji CEPORA – Centra za pozitivan razvoj dece i omladine, uz finansijsku podršku Misije OEBS-a u Srbiji. Dodatno, sprovedena je i kvalitativna analiza kroz fokus-grupne intervjue sa zaposlenima iz šest osnovnih škola (Beograd, Novi Sad, Kragujevac, Niš, Leskovac, Novi Pazar). Rezultati pokazuju da se nastavnici prilično dobro snalaze u reagovanju na izmenjene okolnosti i rad u novim uslovima, ali i dalje postoji značajan udeo njih koji se susreću sa izazovima u svom vaspitno-obrazovnom radu. Tako, 45% nastavnika ističe da ima teškoće u evaluaciji nastavnog procesa, 43% da se susreće sa izazovima pri implementaciji modela nastave na daljinu, a 39% i dalje ima raznovrsne izazove sa upotrebom digitalnih platformi. Zaposleni u školama ističu i da sami uslovi rada nisu ostavili mnogo prostora za vaspitni rad sa učenicima i da je fokus u mnogome bio usmeren na akademski deo obrazovno-vaspitnog procesa. Edukativno-preventivnih aktivnosti sa učenicima praktično nije bilo. Primećuju se promene u ponašanju učenika, te nastavnici ističu da su prisutni problemi sa pažnjom i koncentracijom učenika, motivacijom i prekomernom upotrebom interneta kroz igranje igrica i boravak na društvenim mrežama, a javlja se i značajan pad u posvećenosti učenika školi, odnosno školskim obavezama. Dodatno, nastavnici uočavaju da postoji značajan izazov kada je u pitanju socijalna isključenost učenika. Naime, ističu da je pandemija doprinela produbljenju ovog problema na način da su ona deca koja su već isključena od strane svojih vršnjaka ili su bila u riziku od isključivanja, usled izostatka zajedničkih aktivnosti, sada još „udaljenija”, te prepoznaju veliki značaj u uključivanju različitih kooperativnih aktivnosti „uživo” i zajedničkog rada na grupnoj koheziji i timskim ciljevima. Sami nastavnici su otvoreni za podršku i ističu da im je od velike koristi kada, pored unapređenja svog znanja, dobiju praktične alate koji im služe u radu sa učenicima i koji im predstavljaju osnovu za dalje osmišljavanje aktivnosti. Publikacija „Kako do prevencije rizičnih ponašanja učenika: vodič za primenu interaktivnog učenja u radioničarskom radu” nastala je upravo na bazi rezultata sprovedenih istraživanja i zamišljena je kao praktični alat koji će podržati napore nastavnika u direktnom radu sa učenicima, a sa ciljem prevencije rizičnih ponašanja i podsticanja pozitivnog razvoja učenika. Vodič je namenjen kako onim nastavnicima koji se do sada nisu upuštali u radioničarski rad, tako i onim koji imaju višegodišnje iskustvo, a žele da dobiju nove ideje prilagođene radu u COVID i post-COVID „eri”. Ovde mislimo prvenstveno na situaciju u kojoj je uživo interakcija između nastavnika i učenika premeštena u onlajn okruženje, te se javljaju značajne teškoće u osmišljavanju aktivnosti koje će biti visoko-interaktivne i koje će u velikoj meri podstaći učenike na sopstveno angažovanje u procesu učenja. Vodič pred vama napisan je tako da vas vodi kroz proces kreiranja visoko-interaktivnih radionica, baziranih na interaktivnom učenju kao posebno efektivnom modalitetu koji omogućava uspešan rad na prevenciji kako u „normalnim” – prepandemijskim uslovima, tako i u izmenjenim okolnostima izvođenja obrazovno-vaspitnog rada sa učenicima. Pored vodiča sa koracima koji vas vode do uspešnog radioničarskog rada uz visoku aktivnost učenika, u centralnom delu publikacije priredili smo vam pregled tehnika, vežbi i igri koje vam mogu biti od velike pomoći u konkretnom praktičnom radu. U pitanju su alati koje mi aktivno koristimo u našoj radioničarskoj praksi dve decenije unazad, a koje imaju svoje jasno mesto i uporište u savremenim saznanjima prevencijske nauke. Poseban fokus stavljen je na to kako aktivnosti organizovati i u onlajn okruženju (a da zadrže tu visoku dozu interaktivnosti), a kao dodatni vid podrške, snimili smo veliki broj video objašnjenja za izvođenje konkretnih tehnika, igri i vežbi. Nadamo se da ćete u ovom vodiču na jednom mestu dobiti sve potrebne informacije koje će vam pomoći da, kao glavni nosioci vaspitno-obrazovnog procesa, oživite i preventivne aktivnosti u školskoj praksi u stanju produžene krize, a nadamo se uskoro i nakon nje