Bose Hubbard Models with Synthetic Spin-Orbit Coupling: Mott Insulators, Spin Textures and Superfluidity

Motivated by the experimental realization of synthetic spin-orbit coupling for ultracold atoms, we investigate the phase diagram of the Bose Hubbard model in a non-abelian gauge field in two dimensions. Using a strong coupling expansion in the combined presence of spin-orbit coupling and tunable interactions, we find a variety of interesting magnetic Hamiltonians in the Mott insulator (MI), which support magnetic textures such as spin spirals and vortex and Skyrmion crystals. An inhomogeneous mean field treatment shows that the superfluid (SF) phases inherit these exotic magnetic orders from the MI and display, in addition, unusual modulated current patterns. We present a slave boson theory which gives insight into such intertwined spin-charge orders in the SF, and discuss signatures of these orders in Bragg scattering, in situ microscopy, and dynamic quench experiments.Comment: 4 pages + references + supplementary inf

Navarivanje vijenaca monoblok točka (MBT) čelika R7T za željeznička vozila

The steel R7T monoblock wheel material properties are defined by the International Declaration UIC 812-3. Taking into consideration the resurfacing of the rim, the analyzed conditions for the resurfacing, as well as the analysis of the chemical compounds, mechanical characteristics (material hardness, pulling strength, and tenacity), ultrasound and metallographic testing, which proved that the resurfaced rim area has the required characteristics, according to the Declaration UIC 812-3.Svojstva materijala monobloka točkova čelika R7T su određeni po međunarodnoj objavi UIC 812-3. Na temelju navarivanja vijencaovih točkova, istraživanih uvjeta za navarivanje, te ispitivanjem kemijskog sastava, mehničkih svojstava (tvrdoće, vlačne čvrstoće, žilavosti), ultrazvučnim i metalograpskim ispitivanjima, dokazano je da navareni sloj vijenca ima osobine sukladne traženim po objavi UIC 812-3

Flotation of ores and waste waters

World generally requires a very high standard of pollution control, and mining companies pride their organisations as being examples of excellence in this field. Hydrometallurgical mining processes decrease the production of gas and solid pollutants into the atmosphere and maximize the recirculation of solvents at every level of waste waters treatment. The extra electrowinning of metal using the circular hydrometallurgical process ensures that the maximum amount of mined metal is recovered. Reducing pollution helps to improve company profitability

Thermoelectrical manipulation of nanomagnets

We investigate the interplay between the thermodynamic properties and spin-dependent transport in a mesoscopic device based on a magnetic multilayer (F/f/F), in which two strongly ferromagnetic layers (F) are exchange-coupled through a weakly ferromagnetic spacer (f) with the Curie temperature in the vicinity of room temperature. We show theoretically that the Joule heating produced by the spin-dependent current allows a spin-thermo-electronic control of the ferromagnetic-to-paramagnetic (f/N) transition in the spacer and, thereby, of the relative orientation of the outer F-layers in the device (spin-thermo-electric manipulation of nanomagnets). Supporting experimental evidence of such thermally controlled switching from parallel to antiparallel magnetization orientations in F/f(N)/F sandwiches is presented. Furthermore, we show theoretically that local Joule heating due to a high concentration of current in a magnetic point contact or a nanopillar can be used to reversibly drive the weakly ferromagnetic spacer through its Curie point and thereby exchange couple and decouple the two strongly ferromagnetic F-layers. For the devices designed to have an antiparallel ground state above the Curie point of the spacer, the associated spin-thermionic parallel-to-antiparallel switching causes magneto-resistance oscillations whose frequency can be controlled by proper biasing from essentially DC to GHz. We discuss in detail an experimental realization of a device that can operate as a thermo-magneto-resistive switch or oscillator.Comment: This paper, published in J. Appl. Phys. 107, 123706 (2010), is an expanded version of arXiv:0710.5477 (8 pages, 12 figures, two additional authors and experimental section added

Spin-thermo-electronic oscillator based on inverse giant magnetoresistance

A spin-thermo-electronic valve with the free layer of exchange-spring type and inverse magnetoresistance is investigated. The structure has S-shaped current-voltage characteristics and can exhibit spontaneous oscillations when integrated with a conventional capacitor within a resonator circuit. The frequency of the oscillations can be controlled from essentially dc to the GHz range by the circuit capacitance.Comment: 7 pages, 9 figure

Biodiversity of soil yeasts and their importance in sustainable agriculture.

Metode konvencionalne proizvodnje koje se primenjuju u savremenoj poljoprivrednoj proizvodnji, dovele su do narušavanja stabilnosti prirodnih i agroekosistema. Nekontrolisana upotreba pesticida, mineralnih đubriva i drugih sintetičkih hemijskih jedinjenja, predstavljaju opasnost po zdravlje ljudi i okoline. Diverzitet zemljišnih mikroorganizama je od ključnog značaja za održavanje stabilnosti i produktivnosti u ekosistema zbog njihove uloge u procesima transformacije organske materije, uklanjanja toksičnih jedinjenja, formiranja i održavanja strukture zemljišta, stimulacije rasta biljaka, i drugih značajnih uloga. Opštem mikrobnom diverzitetu u zemljištu doprinose i kvasci, jednoćelijski eukariotni mikroorganizmi. Cilj istraživanja je bio stvaranje kolekcije kvasaca iz različitih zemljišta i ispitivanje njihove praktične primene u održivoj poljoprivredi. Za ispitivanje mikrobnog diverziteta zemljišta korišćene su standardne mikrobiološke i molekularna PCR-DGGE metoda. Izolacija kvasaca je izvršena metodom nakupljanja. Dobijeno je jedanaest izolata koji su okarakterisani i identifikovani na osnovu morfoloških, odgajivačkih, ekoloških, biohemijskih i enzimskih karakteristika. Molekularna identifikacija izolata je izvršena umnožavanjem i sekvencioniranjem D1/D2 regiona i poređenjem dobijenih sekvenci sa sekvencama dostupnim u GenBank bazi podataka. Izolati kvasaca su identifikovani do nivoa vrste i to četiri izolata kao Candida tropicalis (2TD2912B, 3TD0905L, 4TD1101S i Avin1312L), četiri izolata kao Cyberlindnera saturnus (CK2404I, 1KD1983V, 2KD3007J i Cvin1610M) i preostala tri kao Schwanniomyces occidentalis (BK0302D) Hanseniaspora uvarum (EK1605T) i Rhodotorula mucilaginosa (SK0809R). Dodatna karakterizacija kvasaca koji pripadaju različitim rodovima je određena pomoću Raman spektroskopije. U cilju ispitivanja mogućnosti primene kvasaca kao stimulatora biljnog rasta (PGP) je određena produkcija indol sirćetne kiseline (IAA), transformacija azotnih jedinjenja i solubilizacija fosfata. Najveća sposobnost solubilizacije fosfora utvrđena je kod izolata Schwanniomyces occidentalis (BK0302D), stvaranje nitrata kod Rhodotorula mucilaginosa (SK0809R), a produkcija indol sirćetne kiseline kod izolata Candida tropicalis (3TD0905L). Antagonizam prema fitopatogenim gljivama Pythium aphanidermatum i Botrytis cinerea je utvrđen primenom dvojnih kultura...Conventional agriculture, which has been applied in modern food production has severely affected ecosystem’s stability. Improper use of pesticides, herbicides, mineral fertilizers, as well as other synthetic compounds, represents a serious threat for the human kind and nature. The diversity of soil microorganisms is crucial for maintaining stability and productivity of the ecosystem. Soil microorganisms play an important role in the processes of transformation of organic matter, removal of toxic compounds, the formation and maintenance of soil structure, stimulation of plant growth, etc. Yeasts belong to unicellular soil microorganisms group that play a significant role in the ecosystem and contribute to the general biodiversity. The aim of this thesis was to create the collection of yeast strains that originate from the different soil types and testing their potential for the application in sustainable agriculture. Standard microbiological and molecular PCR-DGGE method are used to examine the microbial diversity of soil. Yeasts strains have been isolated by the accumulation method. Finally, eleven isolates were characterized and identified based on morphological, cultivation, ecology, biochemical, and enzyme characteristics. Molecular identification was based on multiplication and D1/D2 region sequencing. The obtained sequences have been compared with those from GenBank basis. Yeasts isolates were identified up to the species level: four isolates were Candida tropicalis (2TD2912B, 3TD0905L, 4TD1101S i Avin1312L), four isolates were Cyberlindnera saturnus (CK2404I, 1KD1983V, 2KD3007J i Cvin1610M) and the last three were Schwanniomyces occidentalis (BK0302D), Hanseniaspora uvarum (EK1605T) and Rhodotorula mucilaginosa (SK0809R). Additional characterization was performed with the Raman spectroscopy. Several assays were applied in order to estimate the yeasts potential in plant growth promoting (PGP): indole acetic acid production (IAA), transformation of nitrogen compounds and phosphate solubilisation. The most efficient in matter of solubilisation of phosphate was Schwanniomyces occidentalis (BK0302D), while Rhodotorula mucilaginosa (SK0809R) has the highest potential in the nitrate production..

Transduction of quantum information from charge qubit to nanomechanical cat-state

We suggest a nanoelectromechanical setup and corresponding time protocol of its manipulation by which we transduce quantum information from charge qubit to nanomechanical cat state. The setup is based on the AC Josephson effect between bulk superconductors and mechanically vibrating mesoscopic superconducting island in the regime of the Cooper pair box. Starting with a pure state with quantum information initially encoded into superposition of the Cooper pair box states, applying a specially tailored time protocol upon bias voltage and gate electrodes, we obtain a new pure state with information finally encoded into superposition of nanomechanical coherent states constituting the cat state. This performance is achieved using quantum entanglement between electrical and mechanical states. Nanomechanical cat states serve as a storage of quantum information, motivated by significantly longer decoherence time with respect to the charge qubit states, from which the information can be transdued back to the charge qubit applying the reverse time protocol.Comment: 6 pages, 4 picture

Exotic quantum spin models in spin-orbit-coupled Mott insulators

We study cold atoms in an optical lattice with synthetic spin-orbit coupling in the Mott-insulator regime. We calculate the parameters of the corresponding tight-binding model using Peierls substitution and "localized Wannier states method" and derive the low-energy spin Hamiltonian for fermions and bosons. The spin Hamiltonian is a combination of Heisenberg model, quantum compass model and Dzyaloshinskii-Moriya interactions and it has a rich classical phase diagram with collinear, spiral and vortex phases.Comment: 5 pages, 3 color figure

Apsorpcija ugljikovog dioksida kao kontrola kvalitete natronskog vapna i aparata za disanje sa zatvorenim krugom

The amount of absorbed C02 on soda lime in closed-circuit isolating apparatus is an important physiological and technical parameter. For its determination we used the classical method modified and improved in our laboratory. Soda limes of different quality were tested in standard self-rescuing isolating breathing apparatus and in oxygen SCUBA. The results show that the C02 content absorbed during C02 autonomy can give useful information about construction characteristics of the apparatus when soda lime of known quality is used. This parameter also enables the evaluation of soda lime quality when used in closed-circuit isolating breathing apparatus of well-known characteristics. From the total C02 quantity in the soda lime used in closed-circuit isolating apparatus the user\u27s average energy expenditure can be estimated and accidents with oxygen SCUBA can be reconstructed.Apsorbirani C02 iz natronskog vapna korištenog u izolirajućem aparatu zatvorenog kruga značajan je fiziološki i tehnički parametar. Da bismo ga mogli precizno odrediti koristili smo se klasičnom metodom koja je modificirana i poboljšana u našem laboratoriju. Ispitivanja su provedena s različitim natronskim vapnima u standardnim izolirajućim aparatima za samospašavanje i u autonomnim ronilačkim aparatima s kisikom. Rezultati ovih ispitivanja pokazuju da sadržaj C02 apsorbiran u periodu trajanja autonomije za C02, može dati korisne informacije o konstruktivnim karakteristikama ispitivanih aparata kada se u njima upotrebljava natronsko vapno poznate kvalitete. Ovaj parametar također omogućava ocjenu kvalitete natronskog vapna kada se upotrebljava u aparatu dobro poznatih karakteristika. Ukupna količina C02 iz natronskog vapna upotrijebljenog u izolirajućem aparatu zatvorenog kruga omogućava određivanje prosječne energetske potrošnje a također i rekonstrukciju nesreće s autonomnim ronilačkim aparatima s kisikom