Computational screening study towards redox-active metal-organic frameworks

The metal-organic framework (MOF) MFU-4l containing Co(II) centers and Cl- ligands has recently shown promising redox activity. Aiming for further improved MOF catalysts for oxidation processes employing molecular oxygen we present a density-functional theory (DFT) based computational screening approach to identify promising metal center and ligand combinations within the MFU-4l structural family. Using the O2 binding energy as a descriptor for the redox property, we show that relative energetic trends in this descriptor can reliably be obtained at the hybrid functional DFT level and using small cluster (scorpionate-type complex) models. Within this efficient computational protocol we screen a range of metal center / ligand combinations and identify several candidate systems that offer more exothermic O2 binding than the original Co/Cl-based MFU-4l framework.Comment: 9 pages, 4 figure

Factors affecting egg consumption in young consumers

Submitted 2020-06-11 | Accepted 2020-07-09 | Available 2020-12-01https://doi.org/10.15414/afz.2020.23.mi-fpap.1-6The research was carried out on consumers aged 20 to 30 years. The survey was conducted among the young population, on a sample of 200 respondents; male (M, n = 100) and female (F, n = 100). Respondents were asked to answer three sets of questions: a) egg quality indicators; b) which are the benefits of consuming eggs compared to other animal products; and c) which are the disadvantages of consuming eggs. A Likert scale (min = 1, max = 5) was used to evaluate the responses on the factors that influence egg consumption. The respondents (M 4.50 : F 4.11; P 0.05). Interval estimation of the mean values μ in male and female populations was made. 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Sadržaj i mobilnost mangana u kiselim zemljištima centralne Srbije

The paper gives an overview of many years ivesrigation of Mn status in acid soils of Central Serbia in the term of its content, mobility and availability to cultivated plants. Many studies have shown strongly expressed mobility and high availability of Mn in these soils. However, distribution and mobility of this element among soil layers, in various conditions of oxido – reduction, moisture and temperatures, were very heterogeneous. The largest presence of Mn in acid soils was in oxide fraction (over 50%).U radu je dat pregled višegodišnjeg proučavanja sadržaja, mobilnosti i pristupačnosti mangana u kiselim zemlјištima Centralne Srbije. Brojna istraživanja su pokazala jako izraženu mobilnost i visoku pristupačnost Mn u ovim zemljištima. Takođe, distribucija i mobilnost Mn u zemljišnim horizontima u različitim oksido-redukcijonim uslovima je bila veoma heterogena. Najveće prisustvo Mn u kiselim zemljištima je bilo u frakciji oksida (preko 50%)

Sadržaj (Ni) nikla u nadzemnom delu i zrnu različitih sorti strnih žita

To ensure safe food production, cultivar-specific traits of winter small grains were analysed in terms of mineral nutrition in order to determine differences between small grain (barley, oat and triticale) genotypes in the level of certain heavy metals (Ni). The kernel of mature small grain plants and their vegetative biomass were found to contain quite different levels of Ni, depending on genotype properties and fertilisation systems. Ni content in oat kernel was above toxic levels and cannot be used for safe food production. Barley and triticale samples complied with quality criteria in terms of their Ni levels.U cilju proizvodnje zdravstveno bezbedne hrane ispitivane su sortne specifičnosti ozimih strnih žita, u odnosu na mineralnu ishranu, kako bi se ustanovile međusobne razlike genotipova strnih žita (ječma, ovsa i tritikalea), u odnosu na zastupljenost pojedinih teških metala (Ni). Konstatovano je da zrno zrelih biljaka strnih žita i vegetativna masa imaju veoma različite sadržaje Ni, u zavisnosti od osobina genotipova i sistema đubrenja. Sadržaj Ni u zrnu ovsa, bio je iznad toksičnih sadržaja i ne može se koristiti za proizvodnju zdravstveno bezbedne hrane. Sa aspekta sadržaja Ni u uzorcima ječma i tritikalea, možemo zaključiti da ispitivani uzorci zadovoljavaju kriterijume kvaliteta

UV-blocking sustainable food packaging based on polyhydroxyalkanoate and bacterial pigment prodigiosin

New film materials based on bacterial biomolecules polyhydroxyalkanoate (poly(3- hydroxybutyrate-co-3-hydroxyvalerate) PHBV) and prodigiosin (PG) were produced by solvent casting as a potential food packaging material. Film precursors were obtained in a sustainable manner via microbial fermentation using waste stream-based substrates (cooking oil and second-grade canned meat, after the expiry date). The incorporation of PG into the PHBV has influenced the morphology and functionality of the obtained materials. PG acted as a nucleating agent, affecting in turn PHBV/PG film surface morphology. The films were intensively colored, transparent and blocked UV-light. An increase in PG content decreased film transparency but it did not affect UV-blocking ability. Migration experiments have shown that films possess the potential to release PG into lipophilic food simulant media where it has exhibited antioxidative action. The obtained results suggest that PHBV/PG films can be potentially used as sustainable and active food packaging materials.2nd International Conference on Chemo and BioInformatics, ICCBIKG 2023, September 28-29, 2023 Kragujeva

Uticaj kalcizacije i đubrenja na prinos i iskorišćavanje azota i fosfora biljkama ječma na zemljištu tipa pseudoglej

This paper presents the results of studying the influence of liming and fertilization on yield and utilization of nitrogen and phosphorus in tested genotypes of winter barley grown on soil (type pseudogley) with low pH values. During the three-year long investigation was carried out on the field of Agricultural-chemical school "Dr. George Radic" at the place Kraljevo. The results indicated that the highest effect to yield and coefficient of utilization of N and P2O5 were obtained by application fertilizer prepared by use of NPK, lime and manure (N- 80 kg ha-1, P2O5 -100 kg ha-1, K2O-80 kg ha-1 + CaCO3-5000 kg ha-1 + manure – 20000kg ha- 1). On the base of studied parameters the barley cultivar NS565 was more tolerant to adverse chemical soil characteristics (low pH, low P2O5 content and a high content of mobile Al) and can be recommended as a suitable genotype for barley production on acid soils, especialy after liming of soil.U radu su prikazani rezultati proučavanja uticaja kalcizacije i đubrenja na prinos i iskorišćavanje azota i fosfora ispitivanim genotipovima ozimog ječma na zemljištu niske pH vrednosti tipa pseudoglej. Trogodišnja istraživanja su izvedena u lokalitetu Kraljeva na imanju Srednje poljoprivredno-hemijske škole "dr Đorđe Radić". Dobijeni rezultati su pokazali da je najveći ekekat na prinos i koeficijent iskorišćavanja N i P2O5 iz đubriva ostvaren kombinovanom upotrebom NPK, krečnog i stajskog đubriva (80 kg Nha-1, 100 kg P2O5ha-1, 80 kg K2Oha-1+5.0 t CaCO3ha-1+20 tha-1 stajnjaka). Na osnovu proučavanih parametara sorta ozimog ječma NS 565 je bila tolerantnija na nepovoljne hemijske karakteristike zemljišta (niska pH, nizak sadržaj P2O5 i visok sadržaj mobilnog Al) i može se preporučiti kao pogodan genotip za proizvodnju ječma na kiselim zemljištima, naročito posle njihove kalcizacije

Structural dynamics in Ni–Fe catalysts during CO₂ methanation - role of iron oxide clusters

Bimetallic Ni–Fe catalysts show great potential for CO$_{2}$ methanation concerning activity, selectivity and long-term stability even under transient reaction conditions as required for Power-to-X applications. Various contrary suggestions on the role of iron in this system on CO$_{2}$ activation have been proposed, hence, its actual task remained still unclear. In this study, we used X-ray absorption spectroscopy (XAS) combined with X-ray diffraction (XRD), XAS in combination with modulation excitation spectroscopy (MES) and density functional theory (DFT) to shed detailed light on the role of iron in a bimetallic Ni–Fe based CO$_{2}$ methanation catalyst. During catalyst activation we observed a synergistic effect between nickel and iron that led to higher fractions of reduced nickel compared to a monometallic Ni-based catalyst. By XAS–XRD combined with DFT, we found formation of FeO$_{x}$ clusters on top of the metal particles. Modulation excitation coupled XAS data complemented with DFT calculations provided evidence of a Fe$^{0}$ ⇌ Fe$^{2+}$+ ⇌ Fe$^{3+}$ redox mechanism at the interface of these FeO$_{x}$ clusters. This may promote CO$_{2}$ dissociation. This is the first time that this highly dynamic role of iron has been experimentally confirmed in bimetallic Ni–Fe based catalysts with respect to CO$_{2}$ activation during the methanation reaction and may also be at the origin of better performance of other CO$_{2}$-hydrogenation catalysts. The insight into the structural surface changes reported in this study show the dynamics of the Fe–Ni system and allow the development of realistic surface models as basis for CO$_{2}$ activation and possible intermediates in these bimetallic systems

Tracking the formation, fate and consequence for catalytic activity of Pt single sites on CeO2

Platinum single sites are highly attractive due to their high atom economy and can be generated on CeO$_2$ by an oxidative high-temperature treatment. However, their location and activity are strongly debated. Furthermore, reaction-driven structural dynamics have not been addressed so far. In this study, we were able to evidence platinum-induced CeO$_2$ surface restructuring, locate platinum single sites on CeO$_2$ and track the variation of the active state under reaction conditions using a complementary approach of density functional theory calculations, in situ infrared spectroscopy, operando high-energy-resolution fluorescence detected X-ray absorption spectroscopy and catalytic CO (as well as C$_3$H$_6$ and CH$_4$) oxidation. We found that the onset of CO oxidation is linked to the migration of platinum single sites from four-fold hollow sites to form small clusters containing a few platinum atoms. This demonstrates that operando studies on single sites are essential to assess their fate and the resulting catalytic properties

Varijabilnost prinosa različitih sorti ozimog ječma

This paper presents the results of winter barley cultivars (Rekord, Grand, NS 565 and Nonijus). Varieties were grown in the experimental field of Agro-chemical school "Dr. Djordje Radic"-Kraljevo during two growing seasons. By examining the physical properties of grain, Nonijus was achieved the highest average yield in both growing seasons (4.140 t ha-1, 5.706 t ha-1). The significant difference in the significance between the impact of the year on grain quality in the examined barley varieties was significant for grain yield. The established differences in significance from the point of view of the genotype to the average values of grain yield were statistically not significant.U radu su prikazani rezultati ispitivanja ozimih sorti ječma (Rekord, Grand, NS 565 i Nonijus). Sorte su gajene na oglednom polju Poljoprivredno-hemijske škole „Dr Đorđe Radić“-Kraljevo, tokom dve vegetacione sezone. Ispitivanjem fizičkih osobina zrna, sorta Nonijus je ostvarila najveći prosečan prinos zrna u obe vegetacijske sezone (4,140 t ha-1; 5,706 t ha-1). Utvrđena razlika značajnosti između uticaja godine na kvalitet zrna kod ispitivanih sorti ječma, bila je značajna za prinos zrna. Ustanovljene razlike značajnosti sa stanovišta uticaja genotipa na prosečne vrednosti prinosa zrna statistički nisu bile signifikantne