Strong Homotopy Lie Algebras, Generalized Nahm Equations and Multiple M2-branes

We review various generalizations of the notion of Lie algebras, in particular those appearing in the recently proposed Bagger-Lambert-Gustavsson model, and study their interrelations. We find that Filippov's n-Lie algebras are a special case of strong homotopy Lie algebras. Furthermore, we define a class of homotopy Maurer-Cartan equations, which contains both the Nahm and the Basu-Harvey equations as special cases. Finally, we show how the super Yang-Mills equations describing a Dp-brane and the Bagger-Lambert-Gustavsson equations supposedly describing M2-branes can be rewritten as homotopy Maurer-Cartan equations, as well.Comment: 1+28 page

State and economical benefit of organic production: fields crops and fruits in the world and Montenegro

Organic farming preserve and upgrade the biodiversity of the soil and biodiversity of the entire ecosystem by protecting the environment, plants, and human health. This study analyses organic plant production worldwide and in Montenegro (2000-2020) and discusses the prospects and challenges in developing organic plant production. Geographically, Montenegro has a diverse climate, suitable for the production of more types of fields crops, vegetables and fruits throughout the year. The paper compares the area of organic farms, the number of farmers, and share of organic in the overall agricultural land in the world and Montenegro, Europe, and several European countries similar to Montenegro in terms of relief or area (Switzerland, Slovenia, Slovakia, Estonia, Serbia, and Cyprus). Data were also analysed for a mountainous state, such as Switzerland, and a Mediterranean one, as Cyprus, as by its position and relief, Montenegro is at the same time a mountainous (northern) and a Mediterranean country (southern region). Shows are trends in plant production areas in Montenegro since it gained independence (2006) and comparison with the EU countries. Grassland production prevails in Montenegro with 85.89%, followed by fruit (12.26%) and cereals (1.62%). The total area under organic vegetable covered a small area compared to the production of fodder crops (3951.84 ha), fruit (563.98 ha), medicinal and aromatic plants (232.46 ha) and field crops (74.49 ha). Organic fruit production has the largest share in the northern part of Montenegro. Certified organic production brings benefits because health-safe products are a condition for preserving the environment and health. © Articles by the authors; Licensee UASVM and SHST, Cluj-Napoca, Romania. The journal allows the author(s) to hold the copyright/to retain publishing rights without restriction

On the monoidal structure of matrix bi-factorisations

We investigate tensor products of matrix factorisations. This is most naturally done by formulating matrix factorisations in terms of bimodules instead of modules. If the underlying ring is C[x_1,...,x_N] we show that bimodule matrix factorisations form a monoidal category. This monoidal category has a physical interpretation in terms of defect lines in a two-dimensional Landau-Ginzburg model. There is a dual description via conformal field theory, which in the special case of W=x^d is an N=2 minimal model, and which also gives rise to a monoidal category describing defect lines. We carry out a comparison of these two categories in certain subsectors by explicitly computing 6j-symbols.Comment: 43 pages; v2: corrected a mistake in sec. 1 and app. A.1, the results are unaffected; v3: minor change

Stabilization/solidification of spent grit in fly ash based geopolymers

Stabilization/solidification (S/S) method is a potential solution for immobilization of heavy metals containing waste. Immobilization of heavy metals from spent grit, waste material from the shipbuilding and ship repair industry, into the fly ash based geopolymers using the S/S method was evaluated. Addition of spent grit in the quantity of 10% of total solid content of geopolymer mixture decreased the compressive strength of fly ash based geopolymers but did not affect the change of geopolymer strength in function of synthesis parameters. TCLP and EN 12457-2 leaching test were used for the evaluation of chemical stability of contaminated geopolymers with respect to the leaching of heavy metals. The both, TCLP and EN 12457 leachates fulfill the maximum acceptable limits for landfill disposal with respect to the heavy metals concentration. The highest concentration of Zn is observed in a both, TCLP and EN 12457 leachates due to the synthesis parameters

Strength, microstructure and durability of steel slag based geopolymers

Elektropećna prašina je nus proizvod koji se dobija pri pretapanju čeličnog otpada u elektropećima. Obzirom da sdrži izvjesnu količinu silicijuma i aluminijuma može se smatrati potencijalnom sirovinom za proces geopolimerizacije. Geopolimerizacija uključuje alkalnu aktivaciju čvrstog alumosilikatnog materijala sa jako alkalno silikatnim rastvorom pri čemu se dobija proizvod koji se uspješno može koristiti u građevinarstvu. Ovo istraživanje je imalo za cilj da ispita uticaj sastava alkalnog aktivatora tj. uticaj alkalnog jona (Na+ ili K+ ) na čvrstoću, mikrostrukturu i postojanost geopolimerana bazi ELPT u agresivnim sredinma.Resultati su pokazali da se Na-geopolimeri karakterišu većom čvrstoćom ali slabijom postojanošću agresivnim sredinama u odnosu na K-geopolimer. Mikrostruktura i Na- i K- geopolimera se karakteriše prisustvom C-(A)-S-H gela koji sadrži i izvjesnu količinu alkalnog jona.Electric arc furnace slag (EAFS) is a by-product of steel scrap remelting in electric arc furnaces. It contains a certain quantity of silica and aluminum so it may be considered as a possible source for a geopolymerization process. Geopolymerization involves alkali activation of solid aluminosilicate materials with highly alkali silicate solution yielding a new product which can successfully be applied in civil engineering. The aim of this paper was to investigate the influence of alkali activator composition i.e. influence of an alkali ion ( Na+ and K+ ) on the strength, microstructure and durability of EAFS based geopolymers in an aggressive environment. The results have shown that Na- geopolymers are characterized by higher strength but lower durability, in comparison to the K-geopolymers. Microstructures of both, Naand K- geopolymers are characterized by the presence of C-(A)-S-H gel which incorporates some alkali ions

Influence of Na

Electric arc furnace dust (EAFD) is by-product of iron and steel scrap remelting in electric arc furnace. This waste is classified as a hazardous material due to the leaching of heavy metals into the environment. Geopolymeryzation of fly ash into construction materials called - geopolymer is a considering as a possible way of immobilization of heavy metals from EAFD. Mechanical properties and chemical stability of geopolymers are mostly determined by the ratio between main oxides, Na2O, Al2O3 and SiO2. In this paper we have investigated possibility of Pb immobilization from EAFD into the fly ash based geopolymer. Geopolymers are synthesized at different Na2O/Al2O3 and SiO2/Al2O3 ratios. Compressive strength and chemical stability of geopolymers with respect to the leaching of Pb in water according to the EN 12457 regulation were tested. The results have shown that Na2O/Al2O3 and SiO2/Al2O3 ratios have influence on the compressive strength of geopolymers and Pb release in the water environment

Influence of Na2O/Al2O3 and SiO2/Al2O3 ratios on the immobilization of Pb from electric arc furnace into the fly ash based geopolymers

Electric arc furnace dust (EAFD) is by-product of iron and steel scrap remelting in electric arc furnace. This waste is classified as a hazardous material due to the leaching of heavy metals into the environment. Geopolymeryzation of fly ash into construction materials called - geopolymer is a considering as a possible way of immobilization of heavy metals from EAFD. Mechanical properties and chemical stability of geopolymers are mostly determined by the ratio between main oxides, Na2O, Al2O3 and SiO2. In this paper we have investigated possibility of Pb immobilization from EAFD into the fly ash based geopolymer. Geopolymers are synthesized at different Na2O/Al2O3 and SiO2/Al2O3 ratios. Compressive strength and chemical stability of geopolymers with respect to the leaching of Pb in water according to the EN 12457 regulation were tested. The results have shown that Na2O/Al2O3 and SiO2/Al2O3 ratios have influence on the compressive strength of geopolymers and Pb release in the water environment