The Lece mine is characterized by the fact that it has gold and silver besides the main valuable components in the flotation concentrates of lead and zinc. Practically since the opening of the mine and flotation, research has been carried out with the aim of obtaining better technological indicators on all four valuable metals (lead, zinc, gold and silver), especially on gold. This paper represents a contribution to that research in order to increase the recovery of gold in flotation concentrates. Gold occurs in ore in several ways (native, with lead and zinc, with pyrite and quartz), which requires a complex technological scheme of gold valorization. Most of the gold is bound to galena and is valorized through lead concentrate. A smaller part of the gold is bound to zinc and is valorized through zinc concentrate. However, about 25% of the gold remains in tailings. Researchers ie. the authors of this paper tried to valorize part of the gold that is lost in the tailings by introducing a third pyrite concentrate with an increased gold content. The paper presents the results of laboratory experiments on the possibility of obtaining pyrite concentrate from the Lece tailings and a proposal for a technological scheme of the process.

Gate-tunable spin-dependent properties could be induced in graphene at room temperature through the magnetic proximity effect by placing it in contact with a metallic ferromagnet. Because strong chemical bonding with the metallic substrate makes gating ineffective, an intervening passivation layer is needed. Previously considered passivation layers result in a large shift of the Dirac point away from the Fermi level, so that unrealistically large gate fields are required to tune the spin polarization in graphene (Gr). We show that a monolayer of Au or Pt used as the passivation layer between Co and graphene brings the Dirac point closer to the Fermi level. In the $\text{Co}/\text{Pt}/\text{Gr}$ system the proximity-induced spin polarization in graphene and its gate control are strongly enhanced by the presence of a surface band near the Fermi level. Furthermore, the shift of the Dirac point could be eliminated entirely by selecting submonolayer coverage in the passivation layer. Our findings open a path towards experimental realization of an optimized two-dimensional system with gate-tunable spin-dependent properties.

Large screen displays are omnipresent today as a part of infrastructure for presentations and entertainment. Also powerful smartphones with integrated camera(s) are ubiquitous. However, there are not many ways in which smartphones and screens can interact besides casting the video from a smartphone. In this paper, we present a novel idea that turns a smartphone into a direct virtual pointer on the screen using the phone's camera. The idea and its implementation are simple, robust, efficient and fun to use. Besides the mathematical concepts of the idea we accompany the paper with a small javascript project (this http URL) which demonstrates the possibility of the new interaction technique presented as a massive multiplayer game in the HTML5 framework.

Instead of the commonly used chemical doping, it can be more favorable to consider transforming graphene through proximity effects by carefully choosing its adjacent regions. While gate-tunable room-temperature spin-dependent properties could be induced in graphene by magnetic proximity effects from common metallic ferromagnets, this approach is complicated by chemical bonding between a metal and graphene suggesting the need for an intervening buffer layer. However, even with a buffer layer there is still a large energy shift of the Dirac cone in graphene away from the Fermi level. Compared to such a large negative shift and its resulting $n$-doping when graphene is separated from cobalt by a monolayer h-BN or another layer of graphene, we show that it can be favorable to instead separate graphene by a monolayer of gold or platinum. The resulting proximity induced magnetization is larger, energy shift is somewhat reduced and changes its sign, offering a path for proximity-induced spin polarization in graphene which can be tuned at smaller gate-controlled electric field than for the h-BN buffer layer.

Peptides are very common recognition entities which are usually attached to surfaces using multistep processes. These processes require modification of the native peptides and of the substrates. Using functional groups in native peptides for their assembly on surfaces without affecting their biological activity can facilitate the preparation of biosensors. Herein we present a simple single-step formation of native oxytocin monolayer on gold surface. These surfaces were characterizations by atomic force spectroscopy, spectroscopic ellipsometry and x-ray photoelectron spectroscopy. We took advantage of the native disulfide bridge of the oxytocin for anchoring the peptide to the Au surface, while preserving the metal ion binding properties. Self-assembled oxytocin monolayer was used by electrochemical impedance spectroscopy for metal ion sensing leading to sub-nanomolar sensitivities for zinc or copper ions.

Proper inclusion of van der Waals interactions (vdW) in ab initio calculations based on the density functional theory (DFT) is crucial to describe soft, organic, layered solids such as κ -(BEDT-TTF) 2 X . Since no consensus has been reached on the reliability of available vdW DFT functionals, most of the first principles calculations have been based on experimental crystal structure data without any structural optimization. Here, we explore optimal DFT-based schemes that account for the effects of vdW interactions on the structural and electronic band properties of three paradigmatic charge transfer salts, κ -(BEDT-TTF) 2 Cu 2 (CN) 3 , κ -(BEDT-TTF) 2 Ag 2 (CN) 3 , and κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl, for which a unified optimization of the structure is possible. Detailed examination of the prototype test system κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl shows that the optB88-vdW functional performs slightly better than the PBE-vdW and that the choice of pseudopotentials is critical to obtaining realistic results.

: Proper inclusion of van der Waals interactions (vdW) in ab initio calculations based on the density functional theory (DFT) is crucial to describe soft, organic, layered solids such as κ -(BEDT-TTF) 2 X . Since no consensus has been reached on the reliability of available vdW DFT functionals, most of the first principles calculations have been based on experimental crystal structure data without any structural optimization. Here, we explore optimal DFT-based schemes that account for the effects of vdW interactions on the structural and electronic band properties of three paradigmatic charge transfer salts, κ -(BEDT-TTF) 2 Cu 2 (CN) 3 , κ -(BEDT-TTF) 2 Ag 2 (CN) 3 , and κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl, for which a unified optimization of the structure is possible. Detailed examination of the prototype test system κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl shows that the optB88-vdW functional performs slightly better than the PBE-vdW and that the choice of pseudopotentials is critical to obtaining realistic results.

A unique technology of direct selective flotation is in use in flotation plant of the "Rudnik" mine in order to obtain selective lead, copper and zinc concentrates. Technological process is very sensitive to so-called "selectivity" because loss of individual metals through selective concentrates is present. Copper minerals flotation cycle is especially sensitive to selectivity and sometimes there is a higher content of lead and zinc minerals present in copper concentrate which is penalized. In this paper laboratory research results of lowering galena and zinc content in copper concentrate possibility due to extended time of cleaning are shown. All experiments were carried out on copper concentrate samples taken from the "Rudnik" flotation plant. Copper concentrate mineralogical analysis were carried out before flotation experiments.

Organic layered charge-transfer salts κ -(BEDT-TTF) 2 X form highly frustrated lattices of molecular dimers in which strong correlations give rise to Mott insulating states situated close to the metal-to-insulator phase boundary. The salts κ -(BEDT-TTF) 2 Cu 2 (CN) 3 and κ -(BEDT-TTF) 2 Ag 2 (CN) 3 have been considered as prime candidates for a quantum spin liquid, while κ -(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl has been suggested as a prototypical charge-order-driven antiferromagnet. In this paper, we summarize and discuss several key results, including some not reported previously, obtained in search to clarify the competition of these two ground states. The origin of anomalous dielectric response found at low temperatures in all three salts is also discussed. We conclude by pointing out the relevant new insights into the role of frustration and random disorder in the suppression of magnetic ordering and formation of the spin liquid state.

Selectivity in mechanochemical cocrystal formation between nicotinamide and anthranilic acid or salicylic acid was studied using tandem in situ reaction monitoring by powder X-ray diffraction (PXRD) and Raman spectroscopy. Selectivity was probed by offering a competing cocrystal coformer to a previously prepared cocrystal or under competitive reaction conditions where all cocrystal coformers, in different stoichiometric ratios, were introduced together in the starting reaction mixture. Reaction paths were dependent on the starting mixture composition, and we find that the formation of intermediates and the final product can be predicted from solid-state ab initio calculations of relative energies of possible reaction mixtures. In some cases, quantitative assessment revealed different reaction profiles derived from PXRD and Raman monitoring, directly indicating, for the first time, different mechanochemical reactivity on the molecular and the bulk crystalline level of the reaction mixture.