Photoinduced dichroism and optical anisotropy in a liquid-crystalline azobenzene side chain polymer caused by anisotropic angular distribution of trans and cis isomers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Lev M. Blinov, Mikhail V. Kozlovsky, Masanori Ozaki, Kent Skarp, andKatsumi Yoshino, Journal of Applied Physics 84, 3860 (1998) and may be found at https://doi.org/10.1063/1.368565

Separate measurements of the flexoelectric and surface polarization in a model nematic liquid crystal p-methoxybenzylidene-p´-butylaniline : Validity of the quadrupolar approach

The temperature dependences of the surface polarization have been measured at the interface of a conductive glass with both the homogeneously and homeotropically oriented nematic liquid crystal p-methoxybenzylidene-p´-butylaniline. The polarization was found in the field-off regime from the pyroelectric response of a cell to a short laser pulse, absorbed in the bulk of the liquid crystal. The temperature increment was calculated from the measurements of the birefringence induced by the same light pulse. It has been shown that the surface polarization at the homeotropic (mh) and planar (mp) interfaces is directed from an interface into the bulk and from the bulk to an interface, respectively (with a magnitude mh~— 0.3 pC/m and mp' ≈ 0.2 pC/m at 25℃). The experimental data may be explained in terms of the quadrupole model of the order-electric polarization with account of some additional contribution from molecular dipoles. The same technique also allows for the measurements of the z component of the flexoelectric polarization using a pyroelectric response of a hybrid (homeoplanar) aligned nematic cell and proper subtracting of the surface contributions. The flexoelectric polarization has been shown to be opposite to the sum of the surface terms mh + mp and directed from the planar to homeotropic interface. This means that the sum of the flexoelectric coefficients e=(e1 + e3) is positive (e ≅ 1.7 pC/m at 28℃). The temperature dependence of e has been shown to involve a combination of both the quadrupolar and dipolar contributions

Impacto da educação e da formação no desenvolvimento do capital intelectual de uma organização na economia digital

An urgent contemporary trend in the development of the economic system is the development of digital technologies, which has intensified due to the coronavirus pandemic. At this stage, the role of intellectual capital as the main system-forming factor of the digital economy is increasing, which makes it necessary to improve the tools for its formation and development. The purpose of this work was to consider changes in the elements of an organization’s intellectual capital in the context of the digital economy compared with the traditional one. The conducted research allowed concluding about the change in the content of the intellectual capital elements, as well as about the shift in emphasis both within the elements and between them. The results can be used as a guideline when making managerial decisions aimed at forming and developing the organization’s intellectual capital considering the specifics of the processes of the economy digitalization.Una tendencia contemporánea urgente en el desarrollo del sistema económico es el desarrollo de las tecnologías digitales, que se ha intensificado debido a la pandemia del coronavirus. El papel del capital intelectual como principal factor de formación de la economía digital es cada vez mayor, lo que hace necesario mejorar las herramientas para su formación y desarrollo. Este trabajo analizó los cambios en los elementos del capital intelectual de una organización en el contexto de la economía digital en comparación con la tradicional. La investigación realizada permitió concluir sobre el cambio en el contenido de los elementos del capital y en el énfasis dentro de los elementos y entre ellos. Los resultados pueden servir de orientación a la hora de tomar decisiones de gestión encaminadas a formar y desarrollar el capital intelectual de la organización teniendo en cuenta las particularidades de los procesos de digitalización de la economía.Uma tendência contemporânea urgente no desenvolvimento do sistema econômico é o desenvolvimento de tecnologias digitais, que se intensificou devido à pandemia de coronavírus. Nessa fase, o papel do capital intelectual como principal fator de formação do sistema da economia digital está aumentando, o que torna necessário melhorar as ferramentas para sua formação e desenvolvimento. O objetivo deste trabalho foi considerar mudanças nos elementos do capital intelectual de uma organização no contexto da economia digital, em comparação com a economia tradicional. A pesquisa conduzida permitiu concluir sobre a mudança no conteúdo dos elementos do capital intelectual, bem como sobre a mudança de ênfase tanto dentro dos elementos como entre eles. Os resultados podem ser usados como uma diretriz na tomada de decisões gerenciais destinadas a formar e desenvolver o capital intelectual da organização, considerando as especificidades dos processos de digitalização da economia

Effects of magnetic and structural phase transitions on the normal and anomalous Hall effects in Ni-Mn-In-B Heusler alloys

Magnetization, electrical resistivity, magnetoresistance, and Hall resistivity of Ni50Mn35In14.25B0.75 and Ni50Mn35In14.5B0.5 Heusler alloys were studied in a temperature range T=80-400K in magnetic fields up to 20 kOe. Both alloys exhibit a martensitic transformation from a higherature ferromagnetic austenite phase to a lowerature, low-magnetization martensitic phase. The electrical resistivity nearly doubles as a result of the martensitic transformation, reaching 180 and 100 μ cm in the martensitic states of Ni50Mn35In14.25B0.75 and Ni50Mn35In14.5B0.5, respectively. The temperature dependence of the electrical resistivity does not corresponded with the Mooij correlation. The magnetoresistance is negative with a narrow negative peak at the martensitic transition. Normal and anomalous Hall effect coefficients were determined by fitting the field dependences of the Hall resistivity using magnetization data. The coefficients of the normal Hall effect for both compositions were found to decrease with temperature from positive values in the austenite to negative values in the martensite phase. None of the known correlations between the anomalous Hall effect coefficient and resistivity were satisfied. Significant changes in the values of the anomalous Hall coefficients during the martensitic transformation are explained by the difference in spin-up and spin-down state occupations in the martensite and austenite phases. First-principles calculations of the electronic structures confirm this explanation

Giant field-induced adiabatic temperature changes in In-based off-stoichiometric Heusler alloys

Direct measurements of the adiabatic temperature change (ΔTAD) of Ni50Mn35In14.5B0.5 have been done using an adiabatic magnetocalorimeter in a temperature range of 250-350 K, and with magnetic field changes up to ΔH = 1.8 T. The initial susceptibility in the low magnetic field region drastically increases with temperature starting at about 300 K. Magnetocaloric effects parameters, adiabatic temperature changes, and magnetic entropy changes were found to be a linear function of H2/3 in the vicinity of the second order transitions (SOT), whereas the first order transitions do not obey the H2/3 law due to the discontinuity of the transition. The relative cooling power based on the adiabatic temperature change for a magnetic field change of 1.8 T has been estimated. Maximum values of ΔTAD = −2.6 K and 1.7 K were observed at the magnetostructural transition (MST) and SOT for ΔH = 1.8 T, respectively. The observed ΔTAD at the MST exceeds the ΔTAD for Ni50Mn35In14X with X = In, Al, and Ge by more than 20% and is larger than the Gd based Heusler alloys

Effects of the partial substitution of Ni by Cr on the transport, magnetic, and magnetocaloric properties of Ni50Mn37In13

The structural, magnetic, and magnetotransport properties of Ni50-xCrxMn37In13 Heusler alloys have been synthesized and investigated by x-ray diffraction (XRD), field and pressure dependent magnetization, and electrical resistivity measurements. The partial substitution of Ni by Cr in Ni50Mn37In13 significantly improves the magnetocaloric effect in the vicinity of the martensitic transition (TM). This system also shows a large negative entropy change at the Curie temperature (TC), making it a candidate material for application in a refrigeration cycle that exploits both positive and negative magnetic entropy changes. The refrigeration capacity (RC) values at TM and TC increase significantly by more than 20 % with Cr substitution. The application of hydrostatic pressure increases the temperature stability of the martensitic phase in Ni45Cr5Mn37In13. The influence of Cr substitution on the transport properties of Ni48Cr2Mn37In13 is discussed. An asymmetric magnetoresistance, i.e., a spin-valve-like behavior, has been observed near TM for Ni48Cr2Mn37In13

Blind trials of computer-assisted structure elucidation software

<p>Abstract</p> <p>Background</p> <p>One of the largest challenges in chemistry today remains that of efficiently mining through vast amounts of data in order to elucidate the chemical structure for an unknown compound. The elucidated candidate compound must be fully consistent with the data and any other competing candidates efficiently eliminated without doubt by using additional data if necessary. It has become increasingly necessary to incorporate an <it>in silico </it>structure generation and verification tool to facilitate this elucidation process. An effective structure elucidation software technology aims to mimic the skills of a human in interpreting the complex nature of spectral data while producing a solution within a reasonable amount of time. This type of software is known as computer-assisted structure elucidation or CASE software. A systematic trial of the ACD/Structure Elucidator CASE software was conducted over an extended period of time by analysing a set of single and double-blind trials submitted by a global audience of scientists. The purpose of the blind trials was to reduce subjective bias. Double-blind trials comprised of data where the candidate compound was unknown to both the submitting scientist and the analyst. The level of expertise of the submitting scientist ranged from novice to expert structure elucidation specialists with experience in pharmaceutical, industrial, government and academic environments.</p> <p>Results</p> <p>Beginning in 2003, and for the following nine years, the algorithms and software technology contained within ACD/Structure Elucidator have been tested against 112 data sets; many of these were unique challenges. Of these challenges 9% were double-blind trials. The results of eighteen of the single-blind trials were investigated in detail and included problems of a diverse nature with many of the specific challenges associated with algorithmic structure elucidation such as deficiency in protons, structure symmetry, a large number of heteroatoms and poor quality spectral data.</p> <p>Conclusion</p> <p>When applied to a complex set of blind trials, ACD/Structure Elucidator was shown to be a very useful tool in advancing the computer's contribution to elucidating a candidate structure from a set of spectral data (NMR and MS) for an unknown. The synergistic interaction between humans and computers can be highly beneficial in terms of less biased approaches to elucidation as well as dramatic improvements in speed and throughput. In those cases where multiple candidate structures exist, ACD/Structure Elucidator is equipped to validate the correct structure and eliminate inconsistent candidates. Full elucidation can generally be performed in less than two hours; this includes the average spectral data processing time and data input.</p