Rare earth and transition metal based entropy stabilised perovskite type oxides

Multicomponent oxides with perovskite type of structure containing up to 10 different cations in equiatomic amounts have been synthesised for the first time. Out of eleven systems synthesised, only six systems crystallised as single phase perovskite type compounds with random and homogenous cation distribution on the respective sites. The formation of phase pure 10-cationic system, (Gd_0.2La_0.2Nd_0.2Sm_0.2Y_0.2)(Co_0.2Cr_0.2Fe_0.2Mn_0.2Ni_0.2)O₃, in contrast to the multiphase mixtures observed in five of the lower entropy systems (containing 6 cations) indicates a possible role of entropy in the stabilisation of a single phase crystal structure. The entropy driven structural stabilisation effect is further supported by the reversible phase transformation, from single phase to multiple phase upon cyclic heat treatment, observed in the (Gd_0.2La_0.2Nd_0.2Sm_0.2Y_0.2)MnO₃ system. This type of entropic signature has been observed in rocksalt based high entropy oxide systems. However, it has not been reported before for perovskite based compounds, as shown in this study.     

Functional synthesis for linear arithmetic and sets

Synthesis of program fragments from specifications can make programs easier to write and easier to reason about. To integrate synthesis into programming languages, synthesis algorithms should behave in a predictable way—they should succeed for a well-defined class of specifications. To guarantee correctness and applicability to software (and not just hardware), these algorithms should also support unbounded data types, such as numbers and data structures. To obtain appropriate synthesis algorithms, we propose to generalize decision procedures into predictable and complete synthesis procedures. Such procedures are guaranteed to find the code that satisfies the specification if such code exists. Moreover, we identify conditions under which synthesis will statically decide whether the solution is guaranteed to exist and whether it is unique. We demonstrate our approach by starting from a quantifier elimination decision procedure for Boolean algebra of set with Presburger arithmetic and transforming it into a synthesis procedure. Our procedure also works in the presence of parametric coefficients. We establish results on the size and the efficiency of the synthesized code. We show that such procedures are useful as a language extension with implicit value definitions, and we show how to extend a compiler to support such definitions. Our constructs provide the benefits of synthesis to programmers, without requiring them to learn new concepts, give up a deterministic execution model, or provide code skeletons.     

Implication of food safety measures on microbiological quality of raw and pasteurized milk

The effects of implementing food safety measures including pre-requisite programs (PRPs) and/or Hazard Analysis Critical Control Points (HACCP) on the microbiological quality of raw and pasteurized milk during four years was investigated in one of the biggest diary plant in Serbia. On the dairy farm, the measures included training of farmers, investments in the infrastructure of gathering points for the collection of raw milk and transportation, improvement of hygiene and decrease of the number of small farmers. As a result of these measures, the contribution of raw milk with of lower total plate count (TPC) in total raw milk quantity decreased over time.As a result of HACCP system implementation in the dairy plant, TPC of pasteurized milk decreased from 3.32 ± 0.48 till 3.11 ± 0.30 log CFU/ml. Eight months after HACCP system was implemented, a significant decrease in TPC from 3.11 ± 0.30 till 2.18 ± 0.54 log CFU/ml in pasteurized milk which could be related to the additional investments covering pasteurisation unit and automated cleaning and disinfection system. The research confirmed constrains of a solely HACCP system without adequate PRPs.Food safety improvements through PRPs and HACCP both on farm level and in the dairy plant present a basis for the production of dairy products.     

Phenolics as antioxidants in garlic (Allium sativum L., Alliaceae)

The antioxidant activities of polar fractions of mature garlic bulbs and immature plants in four different model systems are presented. Antioxidant activity was evaluated as free radical-scavenging capacity (RSC), together with the effect on lipid peroxidation (LP). RSC was assessed by measuring the scavenging activity of garlic extracts on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide. Effects on LP were evaluated by following the activities of examined garlic extracts in Fe²⁺/ascorbate and Fe²⁺/H₂O₂ systems of induction. Investigated extracts reduced the DPPH radical formation (IC₅₀ ranging from 1.03 to 6.01 mg/ml) and neutralised H₂O₂ (IC₅₀ ranging from 0.55 to 2.01 mg/ml) in a dose-dependent manner. Strong inhibition of LP in both systems of induction was observed for all tested garlic extracts. Various levels of phenolics (0.05–0.98 mg gallic acid equivalents/g of dry extract) and flavonoid aglycones (4.16–6.99 μg quercetin equivalents/g of dry extract) in the investigated extracts of garlic could explain the obtained differences in these results only partially.     

Effects of chromium(VI) reducing agents in cement on corrosion of reinforcing steel

During the production of cement it is necessary to add a reducing agent that converts soluble hexavalent chromium into trivalent chromium. This paper explores effects of iron(II) sulphate reducing agents, namely monosulphate and heptahydrate, as cement admixtures, on corrosion of concrete reinforcement. Accelerated corrosion tests of reinforcing steel have been performed in pore solutions simulating concrete prepared using either CEM I or CEM II type cement, with addition of various concentrations of iron(II) sulphate reducing agent. All of the test results indicate corresponding tendencies and point towards the potential for iron(II) sulphate to foster or accelerate corrosion of the reinforcement. The results of this study indicate an immediate need for a more detailed research, especially in concrete as a more realistic corrosion environment, of the application of iron(II) sulphate as a reducing agent in cement.     

Chemical Vapor Synthesis of FeOx–BaTiO3 Nanocomposites

Nanocomposite powders of FeO_x–BaTiO₃ (FO‐BTO) have been prepared by chemical vapor synthesis (CVS) in a single‐step process. The optimal parameters (reactor temperature, reactor length, precursor ratio) for the synthesis were investigated in an initial step for the individual systems, iron oxide (FO), and barium titanate (BTO); and in a second step optimized for the synthesis of the nanocomposites. The solid iron precursor was thermally evaporated, whereas the solid Ba‐ and Ti precursors were vaporized using laser flash evaporation to obtain ultrafine crystalline FO, BTO, and FO‐BTO nanoparticles. The possibility to influence the mass ratios of the two phases in FO‐BTO mixture by adjusting the ratio of the precursor in the two precursor delivery units has been investigated. The potential of CVS for the synthesis of nanocomposites containing iron oxide and barium titanate ultrafine crystalline nanopowders with particle size bellow 10 nm is demonstrated.     

Deciding Effectively Propositional Logic Using DPLL and Substitution Sets

We introduce a DPLL calculus that is a decision procedure for the Bernays-Schönfinkel class, also known as EPR. Our calculus allows combining techniques for efficient propositional search with data-structures, such as Binary Decision Diagrams, that can efficiently and succinctly encode finite sets of substitutions and operations on these. In the calculus, clauses comprise of a sequence of literals together with a finite set of substitutions; truth assignments are also represented using substitution sets. The calculus works directly at the level of sets, and admits performing simultaneous constraint propagation and decisions, resulting in potentially exponential speedups over existing approaches.     

Chemical vapor synthesis of nanocrystalline perovskites using laser flash evaporation of low volatility solid precursors

One key requirement for the production of multinary oxide films by chemical vapor deposition (CVD) or nanocrystalline multinary oxides particles by chemical vapor synthesis (CVS) is the availability of precursors with high vapor pressure. This is especially the case for CVS where much higher production rates are required compared to thin films prepared by CVD. However, elements, which form low valent cations such as alkaline earth metals, are typically only available as solid precursors of low volatility, e.g., in form of beta-diketonates. This study describes laser flash evaporation as precursor delivery method for CVS of nanocrystalline perovskites. Laser flash evaporation exploits the nonequilibrium evaporation of solid metal organic precursors of low vapor pressure by absorption of the infrared radiation of a CO(2) laser. It is shown that stoichiometric, nanocrystalline particles consisting of SrZrO(3) and SrTiO(3) can be formed from corresponding mixtures of beta-diketonates which are evaporated nonselectively and with high rates by laser flash evaporation.