Physical properties of the thermoelectric cubic lanthanum chalcogenides La3-yX4 (X=S,Se,Te) from first-principles

We report ab-initio calculations of the stability, lattice dynamics, electronic and thermoelectric properties of cubic La3-yX4 (X=S,Se,Te) materials in view of analyzing their potential for thermoelectric applications. The lanthanum motions are strongly coupled to the tellurium motions in the telluride, whereas the motions of both types of atoms are decoupled in the sulfides. Nevertheless, this has no impact on their thermal properties because experimentally all compounds have low thermal conductivity. We believe that this is due to Umklapp scattering of the acoustical modes, notably by the low energy optical modes at about 7-8 meV found in all three chalcogenides, as in cage compounds such as skutterudites or clathrates, even though there are no cages in the cubic Th3P4 structure. We find that the energy bandgap increases from the telluride to the sulfide in good agreement with the experiments. However, due to their similar band structure, we find that all three compounds have almost identical thermoelectric properties. Our results agree qualitatively with the experiments, especially in the case of the telluride for which a great amount of data exists. All our results indicate that the sulfides have strong potential for thermoelectricity and could replace the tellurides if the charge carrier concentration is optimized. Finally, we predict also a larger maximum ZT for the p-type doped materials than for the n-type doped ones, even though compounds with p-doping have still to be synthesized. Thus our results indicate the possibility to make high temperature performing thermo-generators based only on La3X4 compounds.Comment: 37 pages, 12 figure

A first-principles investigation of the thermodynamic and mechanical properties of Ni-Ti-Sn Heusler and half-Heusler materials

First principles calculations of the vibrational, thermodynamic and mechanical properties of the Ni-Ti-Sn Heusler and half-Heusler compounds have been performed. First, we have calculated the Raman and infrared spectra of NiTiSn, providing benchmark theoretical data directly useful for the assignments of its experimental spectra and clarifying the debate reported in the literature on the assignment of its modes. Then, we have discussed the significant vibrational density-of-states of Ni2TiSn at low-frequencies. These states are at the origin of (i) its smaller free energy, (ii) its higher entropy, and (iii) its lower Debye temperature, with respect to NiTiSn. Finally, we have reported the mechanical properties of the two compounds. In particular, we have found that the half-Heusler compound has the largest stiffness. Paradoxically, its bulk modulus is also the smallest. This unusual behavior has been related to the Ni-vacancies that weaken the structure under isostatic compression. Both compounds show a ductile behavior.Comment: 22 pages, 7 figure

Wpływ różnego udziału pasz białkowych w mieszankach oraz czasu przechowywania w warunkach chłodniczych na cechy fizyczne mięsa kurcząt brojlerów

The study aimed at evaluating the effect of feeding broiler chickens with diets containing faba bean and cold storage time on the physical properties of m. pectoralis major. The study material comprised 24 muscles from chickens split into 3 feeding groups. Birds from the control group (I) were fed with compound feeds containing soybean meal as the only highprotein component, whereas the starter/grower diets administered to experimental chickens contained faba bean in the proportion 8/15% - group II and 16/22% - group III, as a partial substitute for soybean meal. No effect of the feeding method on acidity and water absorption capacity of the muscle was observed. Muscles of chickens fed with mixes with a higher share of faba bean were characterised by higher yellow saturation, colour intensity and hue in comparison to other groups. The storage time had no effect on their physical properties; a decrease was only recorded in pH24 of the evaluated muscles, which testifies to the correct course of glycolytic transformations. To sum up, it must be stated that a higher share of faba bean in chicken diets modifies muscle colour only, but cold storage time has no impact on the evaluated physical characteristics of muscles.Celem przeprowadzonych badań było określenie wpływu żywienia kurcząt brojlerów mieszankami zawierającymi śrutę bobikową oraz czasu przechowywania w warunkach chłodniczych na cechy fizyczne m. pectoralis major. Materiał badawczy stanowiły 24 mięśnie pochodzące od kurcząt rzeźnych z 3 grup żywieniowych. Kurczęta grupy kontrolnej (I) żywiono mieszankami, w których jedynym surowcem wysokobiałkowym była poekstrakcyjna śruta sojowa, natomiast do mieszanek starter/grower kurcząt doświadczalnych w miejsce części śruty poekstrakcyjnej sojowej wprowadzono śrutę z bobiku w udziale 8/15% - grupa II lub 16/22% - grupa III. Nie stwierdzono wpływu zastosowanego żywienia na kwasowość i wodochłonność mięśni. Większym nasyceniem barwy żółtej, intensywnością i odcieniem cechowały się mięśnie kurcząt żywionych mieszankami z wyższym udziałem bobiku w porównaniu do pozostałych grup. Czas przechowywania mięśni w warunkach chłodniczych nie miał wpływu na ich właściwości fizyczne, odnotowano jedynie spadek pH24 ocenianych mięśni, co świadczy o prawidłowym przebiegu przemian glikolitycznych. Reasumując, stwierdzić należy, że wprowadzenie wyższego udziału bobiku do mieszanek dla kurcząt modyfikuje jedynie barwę mięśni, natomiast czas przechowywania w warunkach chłodniczych pozostaje bez wpływu na oceniane cechy fizyczne mięśni

Spectrally selective fluorescence imaging of Chlorobaculum tepidum reaction centers conjugated to chelator-modified silver nanowires

A polyhistidine tag (His-tag) present on Chlorobaculum tepidum reaction centers (RCs) was used to immobilize photosynthetic complexes on a silver nanowire (AgNW) modified with nickel-chelating nitrilo-triacetic acid (Ni-NTA). The optical properties of conjugated nanostructures were studied using wide-field and confocal fluorescence microscopy. Plasmonic enhancement of RCs conjugated to AgNWs was observed as their fluorescence intensity dependence on the excitation wavelength does not follow the excitation spectrum of RC complexes in solution. The strongest effect of plasmonic interactions on the emission intensity of RCs coincides with the absorption spectrum of AgNWs and is observed for excitation into the carotenoid absorption. From the absence of fluorescence decay shortening, we attribute the emission enhancement to increase of absorption in RC complexes

Covenant based credit capacity model for real estate capital groups : evidence from Poland

Purpose: The study aims to specify the form of the model used to determine the ability to obtain external financing (net debt) by real estate capital groups. The study also focuses on verifying the covenant function as a tool to limit the scale of projects implemented by real estate holdings. Approach/Methodology/Design: The analysis was carried out based on consolidated financial data of all (residential, commercial, and residential/commercial) real estate capital groups whose bonds are listed on the Catalyst bond in Poland. However, the said model is universal. The paper uses a method of examining documents, a method of analysis, and logical and qualitative construction to formulate new hypotheses, which can then be verified using a quantitative approach based on a larger sample. The Pearson correlation coefficient determined the relationship strength among covenants' pairs and between covenants and sensitivity ratio for the sample and the significance by the statistics t. Findings: The initiative to select covenants and determine their levels lies with issuers rather than investors. The inclusion of ND/EBITDA covenant in 75% of cases would mean an important reduction in credit exposure. The significant correlation among covenants identified in the study means duplication of information about the issuer's risk. Practical Implications: This study's conclusions can be used in the process of structuring the terms and conditions of corporate bond issues and provide important and new information primarily for bondholders in the context of leverage potential and the possibility of risk monitoring using covenants. The application contribution refers to the conclusions from the analysis of the monitoring potential of financial covenants and the influence of covenants on the change in the potential of capital groups due to the tightening of banks' credit policy at the level of special purpose vehicles. Originality/Value: The results of the analysis and theoretical considerations in this article complement existing research in the field of covenants' application by different stakeholders of bond issue programs.peer-reviewe

An alternative carrier solvent for fingermark enhancement reagents

Solstice® Performance Fluid (PF), trans-1-chloro-3,3,3-trifluoropropene, is presented as an alternative to HFE7100, methoxy-nonafluorobutane, as a carrier solvent in a number of chemical formulations used for the visualisation of latent fingermarks. The supply of HFE7100 may be at riskdue to a recent European Union regulation to control global warming. Laboratory trials using split depletions and a pseudo-operational trial of 1000 porous samples have shown that Solstice® PF is a viable alternative to HFE7100 for the chemical formulations of ninhydrin and 1,2-indanedione. Other preliminary trials have also indicated that Solstice® PF can be used as a carrier solvent for the zinc toning of marks found using ninhydrin as well as the α-naphtholflavone fixative solution for iodine developed marks. Results from the pseudo-operational trial demonstrate that the number of marks detected by ninhydrin and 1,2-indanedione formulations for each carrier solvent is comparable. When compared to HFE7100, advantages of Solstice® PF include a very low global warming potential and atmospheric lifetime in addition to a higher wetting index and lower costs. This study also provides a validation study that supports the potential replacement of DFO with 1,2-indanedione

Metabolism of Cryptic Peptides Derived from Neuropeptide FF Precursors: The Involvement of Insulin-Degrading Enzyme

The term “cryptome” refers to the subset of cryptic peptides with bioactivities that are often unpredictable and very different from the parent protein. These cryptic peptides are generated by proteolytic cleavage of proteases, whose identification in vivo can be very challenging. In this work, we show that insulin-degrading enzyme (IDE) is able to degrade specific amino acid sequences present in the neuropeptide pro-NPFFA (NPFF precursor), generating some cryptic peptides that are also observed after incubation with rat brain cortex homogenate. The reported experimental findings support the increasingly accredited hypothesis, according to which, due to its wide substrate selectivity, IDE is involved in a wide variety of physiopathological processes

phi YeO3-12 phage tail fiber Gp17 as a promising high specific tool for recognition of Yersinia enterocolitica pathogenic serotype O : 3

Yersiniosis is an infectious zoonotic disease caused by two enteropathogenic species of Gram-negative genus Yersinia: Yersinia enterocolitica and Yersinia pseudotuberculosis. Pigs and other wild and domestic animals are reservoirs for these bacteria. Infection is usually spread to humans by ingestion of contaminated food. Yersiniosis is considered a rare disease, but recent studies indicate that it is overlooked in the diagnostic process therefore the infections with this bacterium are not often identified. Reliable diagnosis of Yersiniosis by culturing is difficult due to the slow growth of the bacteria easily overgrown by other more rapidly growing microbes unless selec-tive growth media is used. Phage adhesins recognizing bacteria in a specific manner can be an excellent diagnostic tool, es-pecially in the diagnosis of pathogens difficult for culturing. In this study, it was shown that Gp17, the tail fiber protein (TFP) of phage phi YeO3-12, specifically recognizes only the pathogenic Yersinia enterocolitica serotype O:3 (YeO:3) bacteria. The ELISA test used in this work confirmed the specific interaction of this protein with YeO:3 and demonstrated a promising tool for developing the pathogen recognition method based on phage adhesins.Peer reviewe

Physical properties of thermoelectric zinc antimonide using first-principles calculations

We report first principles calculations of the structural, electronic, elastic and vibrational properties of the semiconducting orthorhombic ZnSb compound. We study also the intrinsic point defects in order to eventually improve the thermoelectric properties of this already very promising thermoelectric material. Concerning the electronic properties, in addition to the band structure, we show that the Zn (Sb) crystallographically equivalent atoms are not exactly equivalent from the electronic point of view. Lattice dynamics, elastic and thermodynamic properties are found to be in good agreement with experiments and they confirm the non equivalency of the zinc and antimony atoms from the vibrational point of view. The calculated elastic properties show a relatively weak anisotropy and the hardest direction is the y direction. We observe the presence of low energy modes involving both Zn and Sb atoms at about 5-6 meV, similarly to what has been found in Zn4Sb3 and we suggest that the interactions of these modes with acoustic phonons could explain the relatively low thermal conductivity of ZnSb. Zinc vacancies are the most stable defects and this explains the intrinsic p-type conductivity of ZnSb.Comment: 33 pages, 8 figure