Complexes of silver with histidine and imidazole investigated by the calorimetric and potentiometric methods

The stability constants and enthalpies of formation of silver (I) complexes with histidine and imidazole were determined. Two types of complexes were found: AgL+ and AgL+ 2 . The second is much more stable that is evidenced by the higher stability constants and enthalpies of formation. For the two systems, the respective constants and enthalpies are very close one to another that suggests similar complexation mechanisms. Most probably, the linear complexes through the N-3 pyridinic atoms are being formed. The calorimetric and potentiometric methods gave virtually the same results for the system silver + imidazole. However, the potentiometric method failed for the histidine system. The molecule of histidine has three protonation spots, two of these probably do not take part in the complexation but their protonation equilibria may shift upon joining the ions of silver and influence the pH of the system in that way

The effect of intensive and extensive production systems on carcass quality in New Zealand White rabbits

[EN] Forty New Zealand White rabbits weaned at 30 days were divided into 2 groups and reared under intensive or extensive production system till slaughter age (90 days of age). In the extensive production system, rabbits were housed in free-standing cages on straw litter and fed farm-made feed ad libitum. Control rabbits were raised intensively in wire mesh slatted floor cages, indoors and on a commercial pellet ad libitum. Hot carcass weight was 16,6% lower (P0.05). The higher carcass weight of the control rabbits led to heavier primal cuts, including head (P0.05) and the fore part, intermediate part and hind part of the carcass (P0.01). However, expressed as % of carcass weight, a significantly higher ratio was only found for the head (P0.01) and edible offal (P0.05) in intensively produced rabbits. The production systems investigated had no significant (P>0.05) effect on the chemical composition, physicochemical properties and organoleptic characteristics of meat from New Zealand White rabbits.Daszkiewicz, T.; Gugolek, A.; Janiszewski, P.; Kubiak, D.; Czoik, M. (2012). The effect of intensive and extensive production systems on carcass quality in New Zealand White rabbits. World Rabbit Science. 20(1):25-33. doi:10.4995/wrs.2012.945SWORD253320

Long-lived emission from Eu3+:PbF2 nanocrystals distributed into sol-gel silica glass

This paper reports an optical investigation of Eu3+:PbF2 nanocrystals distributed into silica glasses fabricated by sol–gel methods. The sample microstructure was investigated using scanning transmission electron microscopy. The β-cubic PbF2 crystalline phase was identified using X-ray diffraction analysis. The observed emission bands correspond to 5D0 → 7FJ (J = 0–4) transitions of Eu3+. The spectroscopic parameters for Eu3+ ions were determined based on excitation and emission measurements as well as luminescence decay analysis. Emission originating from 5D0 state of Eu3+ ions in sample containing PbF2 nanocrystals is long-lived in comparison to precursor sol–gel silica glasses

SilE is an intrinsically disordered periplasmic ‘molecular sponge' involved in bacterial silver resistance

Ag+ resistance was initially found on the Salmonella enetrica serovar Typhimurium multi-resistance plasmid pMG101 from burns patients in 1975. The putative model of Ag+ resistance, encoded by the sil operon from pMG101, involves export of Ag+ via an ATPase (SilP), an effluxer complex (SilCFBA) and a periplasmic chaperon of Ag+ (SilE). SilE is predicted to be intrinsically disordered. We tested this hypothesis using structural and biophysical studies and show that SilE is an intrinsically disordered protein in its free apo-form but folds to a compact structure upon optimal binding to six Ag+ ions in its holo-form. Sequence analyses and site-directed mutagenesis established the importance of histidine and methionine containing motifs for Ag+-binding, and identified a nucleation core that initiates Ag+-mediated folding of SilE. We conclude that SilE is a molecular sponge for absorbing metal ions

The risk of entrepreneur mining activity related to hiring employees

Zarządzanie przedsiębiorstwem jest związane z ponoszeniem przez przedsiębiorcę różnorakich ryzyk. Jednym z ważniejszych, wynikającym z zasad obowiązujących w prawie pracy, jest ryzyko związane z zatrudnianiem pracowników. Dotyczy ono systemów prawnych wszystkich państw demokratycznych. Jego poziom jest związany także z coraz szerszą i skuteczniejszą ochroną wolności oraz praw człowieka i obywatela, w tym także pracownika (np. prawo do bezpiecznych i higienicznych warunków pracy, prawo do prywatności, ochrona danych osobowych). W Polsce dodatkowo, z uwagi na uwarunkowania historyczne i dynamikę zmian w okresie transformacji ustrojowej, w niektórych kwestiach ryzyko to ma specyficzny charakter. W skrajnych przypadkach poziom tego ryzyka może decydować o pomyślności realizowanego przedsięwzięcia gospodarczego. Największym problemem jest to, iż przy niektórych rodzajach tego ryzyka pracodawca ma niewielkie możliwości, aby je zminimalizować. Z uwagi na poziom zagrożeń i szeroko rozwiniętą ochronę pracownika, sytuacja ta ma szczególne znaczenie w górnictwie. Celem artykułu jest zwrócenie uwagi na ten problem, gdyż wydaje się, że w demokratycznym państwie prawnym ochrona pracodawcy w tym zakresie powinna być większa.Managing a business is linked with various risks. One of the most important, resulting from the rules of the labor law, is the risk associated with hiring employees. It concerns legal systems all democratic countries. Its level is also increasingly associated with a wider and more effective protection of freedoms and human rights, including employee (eg. the right to safe and healthy working conditions, the right to privacy, protection of personal data). In Poland, due to historical circumstances and dynamic changes in the period of political transformation, in some respects this risk is of specific character. In extreme cases, the level of this risk can decide about economic prosperity of implemented business venture. The biggest problem is the fact that in the case of different types of risk, employer has little opportunities to minimize them. Given the level of threat and a well-developed worker protection, the situation has particular importance in the mining industry. The purpose of this article is to draw attention to this issue, because it seems that in a democratic legal state, protecting the employer in this area should be higher

Influence of Mixed Cationic-nonionic Surfactant Systems on the Spectral Properties of C.I. Mordant Blue 29 and Its Complexes with Iron(III)

<div>Interactions of the anionic form of C.I. Mordant Blue 29 with cationic and nonionic surfactants have been studied by</div><div>absorption spectroscopy. The dye interacts strongly with oppositely charged surfactants in the pre-micellar concentration range with an accompanying change in its spectral properties, while its interaction with the polyoxyethylene group of nonionic surfactants does not have such remarkable effects. In ternary mixtures, however, the influence of the polyoxyethylene group on the optical properties of C.I. Mordant Blue 29 tetradecyltrimethylammonium bromide and C.I.</div><div>Mordant Blue 29-octadecyltrimethylammonium chloride systems is quite different. In addition, the influence of the</div><div>interaction between the HL3– form of C.I. Mordant Blue 29 and the surfactants on the formation of chelate complexes with iron(III) has been studied. The optimized structures of Fe-Mordant Blue 29 complexes are also reported herein.</div><div>Geometries have been calculated by the Hartree–Fock method with the cc-pVDZ basis set.</div

Imidazole-grafted nanogels for the fabrication of organic–inorganic protein hybrids

Here, a platform for the development of highly responsive organic–inorganic enzyme hybrids is provided. The approach entails a first step of protein engineering, in which individual enzymes are armored with a porous nanogel decorated with imidazole motifs. In a second step, by mimicking the biomineralization mechanism, the assembly of the imidazole nanogels with CuSO4 and phosphate salts is triggered. A full characterization of the new composites reveals the first reported example in which the assembly mechanism is triggered by the sum of Cu(II)–imidazole interaction and Cu3(PO4)2 inorganic salt formation. It is demonstrated that the organic component of the hybrids, namely the imidazole‐modified polyacrylamide hydrogel, provides a favorable spatial distribution for the enzyme. This results in enhanced conversion rates, robustness of the composite at low pH values, and a remarkable thermal stability at 65 °C, exhibiting 400% of the activity of the mineralized enzyme lacking the organic constituent. Importantly, unlike in previous works, the protocol applies to the use of a broad range of transition metal cations (including mono‐, di‐, and trivalent cations) to trigger the mineralization mechanism, which eventually broadens the chemical and structural diversity of organic–inorganic protein hybrids.This project had received funding from the Spanish Ministry of Economy and Competitiveness (MINECO) and the FEDER funds in the frame of “Plan Nacional – Retos para la Sociedad” call with the Grant Reference No. MAT2017‐88808‐R. This work was performed under the Maria de Maeztu Units of Excellence Programme – Grant No. MDM‐2016‐0618. A.B. thanks Diputación de Guipúzcoa for current funding in the frame of Gipuzkoa Fellows program. M.K. acknowledges financial support by the Spanish Ministry of Economy and Competitiveness (MINECO) within Grant Agreement No. MAT2016‐77393‐R, including FEDER funds.Peer reviewe