Ab initio study on the magneto-structural properties of MnAs

The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of magnetic order, confirming previous experimental findings and phenomenological models. It is generally found that for large lattice constants the ferromagnetic state is favored, whereas for small lattice constants different antiferromagnetic states can be stabilized. In the ferromagnetic state the structure with minimal energy is always hexagonal, whereas it becomes orthorhombically distorted if there is an antiferromagnetic component in the hexagonal plane. For the paramagnetic state the stable cell is found to be orthorhombic up to a critical lattice constant of about 3.7 Angstrom, above which it remains hexagonal. This leads to the second order structural phase transition between paramagnetic states at about 400 K, where the lattice parameter increases above this critical value with rising temperature due to the thermal expansion. For the paramagnetic state an analytic approximation for the magnitude of the orthorhombic distortion as a function of the lattice constant is given. Within the mean field approximation the dependence of the Curie temperature on the volume and on the orthorhombic distortion is calculated. For orthorhombically distorted cells the Curie temperature is much smaller than for hexagonal cells. This is mainly due to the fact that some of the exchange coupling constants in the hexagonal plane become negative for distorted cells. With these results a description of the susceptibility as function of temperature is given

Periodicities in data observed during the minimum and the rising phase of solar cycle 23; years 1996 - 1999

Three types of observations: the daily values of the solar radio flux at 7 frequencies, the daily international sunspot number and the daily Stanford mean solar magnetic field were processed in order to find all the periodicities hidden in the data. Using a new approach to the radio data, two time series were obtained for each frequency examined, one more sensitive to spot magnetic fields, the other to large magnetic structures not connected with sunspots. Power spectrum analysis of the data was carried out separately for the minimum (540 days from 1 March 1996 to 22 August 1997) and for the rising phase (708 days from 23 August 1997 to 31 July 1999) of the solar cycle 23. The Scargle periodograms obtained, normalized for the effect of autocorrelation, show the majority of known periods and reveal a clear difference between the periodicities found in the minimum and the rising phase. We determined the rotation rate of the `active longitudes' in the rising phase as equal to 444.4 $\pm$ 4 nHz (26\fd0 \pm 0\fd3). The results indicate that appropriate and careful analysis of daily radio data at several frequencies allows the investigation of solar periodicities generated in different layers of the solar atmosphere by various phenomena related to the periodic emergence of diverse magnetic structures.Comment: 15 pages, 8 figure

Effectiveness of actions associated with the environmental protection and the sustainable development

The problem, which for many centuries measured globe is "coexistence" between man and nature. The essential element of this process is the continuous satisfaction of human needs with the use of what nature and the process of globalization have given of themselves. Therefore, the authors of this article research has identified the following problems, namely. Do man can imagine himself without essential environment? Is the action and the human conscience allows him to "surrender" the gifts of fauna and flora? Is in the current progress in the development of society is the human factor that causes people to become empathetic to the devastation of the environment? The present article attempts to answer these questions, and the responses are the hypotheses

Mechanochemical, Sonochemical and Hydrothermal Activation of Niobium Pentoxide and its Catalytic Properties

Modification of niobium pentoxide with different dispersity via mechanochemical, ultrasound, hydrothermal and microwave treatments (MChT, UST, HTT, and MWT, respectively) has been studied. All types of treatment do not change of phase composition but leads to improvement (at HTT and MWT) or, on contrary, breaking of crystal structure (at MChT and UST) and variation of crystallite size and specific surface area. UV-Vis measurements display increase of absorption in visible region. As a result, modified samples show higher photocatalytic activity at degradation of rhodamine B under visible irradiation. Similarly, initial and modified Nb2O5 samples are catalysts for mechanochtmical and sonochemical destruction of the same dye. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3515

Code of ethics as a tool for resolving conflict in the organization

This article addresses the issues as selection tools to resolve conflicts in organizations because of the importance and topicality of this issue. One such tool among these is the effective functioning of the organization code of ethics. This document, the more detailed, the more effective. Nowadays, more and more organizations have their own codes of ethics. Therefore, it would be wrong underestimation of the code of ethics as a tool that could be used to resolve conflicts in organizations

Interpopulation hybridization results in widespread viability selection across the genome in Tigriopus californicus

Background: Genetic interactions within hybrids influence their overall fitness. Understanding the details of these interactions can improve our understanding of speciation. One experimental approach is to investigate deviations from Mendelian expectations (segregation distortion) in the inheritance of mapped genetic markers. In this study, we used the copepod Tigriopus californicus, a species which exhibits high genetic divergence between populations and a general pattern of reduced fitness in F2 interpopulation hybrids. Previous studies have implicated both nuclear-cytoplasmic and nuclear-nuclear interactions in causing this fitness reduction. We identified and mapped population-diagnostic single nucleotide polymorphisms (SNPs) and used these to examine segregation distortion across the genome within F2 hybrids.Results: We generated a linkage map which included 45 newly elucidated SNPs and 8 population-diagnostic microsatellites used in previous studies. The map, the first available for the Copepoda, was estimated to cover 75% of the genome and included markers on all 12 T. californicus chromosomes. We observed little segregation distortion in newly hatched F2 hybrid larvae (fewer than 10% of markers at p < 0.05), but strikingly higher distortion in F2 hybrid adult males (45% of markers at p < 0.05). Hence, segregation distortion was primarily caused by selection against particular genetic combinations which acted between hatching and maturity. Distorted markers were not distributed randomly across the genome but clustered on particular chromosomes. In contrast to other studies in this species we found little evidence for cytonuclear coadaptation. Instead, different linkage groups exhibited markedly different patterns of distortion, which appear to have been influenced by nuclear-nuclear epistatic interactions and may also reflect genetic load carried within the parental lines.Conclusion: Adult male F2 hybrids between two populations of T. californius exhibit dramatic segregation distortion across the genome. Distorted loci are clustered within specific linkage groups, and the direction of distortion differs between chromosomes. This segregation distortion is due to selection acting between hatching and adulthood

Interpopulation hybridization results in widespread viability selection across the genome in Tigriopus californicus

<p>Abstract</p> <p>Background</p> <p>Genetic interactions within hybrids influence their overall fitness. Understanding the details of these interactions can improve our understanding of speciation. One experimental approach is to investigate deviations from Mendelian expectations (segregation distortion) in the inheritance of mapped genetic markers. In this study, we used the copepod <it>Tigriopus californicus</it>, a species which exhibits high genetic divergence between populations and a general pattern of reduced fitness in F2 interpopulation hybrids. Previous studies have implicated both nuclear-cytoplasmic and nuclear-nuclear interactions in causing this fitness reduction. We identified and mapped population-diagnostic single nucleotide polymorphisms (SNPs) and used these to examine segregation distortion across the genome within F2 hybrids.</p> <p>Results</p> <p>We generated a linkage map which included 45 newly elucidated SNPs and 8 population-diagnostic microsatellites used in previous studies. The map, the first available for the Copepoda, was estimated to cover 75% of the genome and included markers on all 12 <it>T. californicus </it>chromosomes. We observed little segregation distortion in newly hatched F2 hybrid larvae (fewer than 10% of markers at p < 0.05), but strikingly higher distortion in F2 hybrid adult males (45% of markers at p < 0.05). Hence, segregation distortion was primarily caused by selection against particular genetic combinations which acted between hatching and maturity. Distorted markers were not distributed randomly across the genome but clustered on particular chromosomes. In contrast to other studies in this species we found little evidence for cytonuclear coadaptation. Instead, different linkage groups exhibited markedly different patterns of distortion, which appear to have been influenced by nuclear-nuclear epistatic interactions and may also reflect genetic load carried within the parental lines.</p> <p>Conclusion</p> <p>Adult male F2 hybrids between two populations of <it>T. californius </it>exhibit dramatic segregation distortion across the genome. Distorted loci are clustered within specific linkage groups, and the direction of distortion differs between chromosomes. This segregation distortion is due to selection acting between hatching and adulthood.</p

Spearmint (\u3cem\u3el\u3c/em\u3e-carvone) Oil and Wintergreen (methyl salicylate) Oil Emulsion is an Effective Immersion Anesthetic of Fishes

This study evaluates the effects of a spearmint (/-carvone) and wintergreen oil (methyl salicylate) emulsion (CMSE) on age 1 landlocked Atlantic salmon Salmo salar sebago (hereafter salmon). Salmon were immersed in either 257 µl/L CMSE or 75 mg/L tricaine methanesulfonate (MS-222) to induce anesthesia (stage 4), useful for emersion and noninvasive husbandry procedures, and then salmon were recovered in fresh water. Induction was quicker in the CMSE group; however, recovery was quicker in the MS-222 group. A second experiment was conducted in which salmon were immersed in 257 µl/L CMSE for 8.5 min, or 75 mg/L MS-222 for 8.5 min in order to compare electrocardiographs during deeper anesthesia (stage 5) between salmon continuously immersed in CMSE to those continuously immersed in MS-222. Because salmon remained sedated longer after CMSE exposure than after MS-222 exposure, a third group of salmon was immersed in 257 µl/L CMSE for just 2.5 min before undergoing the 6-min electrocardiograph procedure. Anesthesia induction rates, recovery rates, and electrocardiographs of salmon anesthetized with CMSE were comparable to salmon anesthetized with MS-222. Salmon anesthetized with CMSE and then transferred immediately to fresh water had more stable heart rates than salmon anesthetized with either MS-222 or CMSE continuously. Salmon bathed continuously in CMSE showed clinical signs of increasing anesthetic depth including decreasing heart rate, decreasing respiration rate and electrocardiograph abnormalities. The CMSE, with its mint and wintergreen concentrations less than in household products such as chewing gum, toothpaste, and mouthwash, is a potent, rapid-acting immersion fish anesthetic comparable to MS-222 for stages 4 and 5 anesthesia

Screen-printed nanoparticles as anti-counterfeiting tags

Metallic nanoparticles with different physical properties have been screen printed as authentication tags on different types of paper. Gold and silver nanoparticles show unique optical signatures, including sharp emission bandwidths and long lifetimes of the printed label, even under accelerated weathering conditions. Magnetic nanoparticles show distinct physical signals that depend on the size of the nanoparticle itself. They were also screen printed on different substrates and their magnetic signals read out using a magnetic pattern recognition sensor and a vibrating sample magnetometer. The novelty of our work lies in the demonstration that the combination of nanomaterials with optical and magnetic properties on the same printed support is possible, and the resulting combined signals can be used to obtain a user-configurable label, providing a high degree of security in anti-counterfeiting applications using simple commercially-available sensors