Synthesis of Nano-Structured Polyaniline by Direct Emulsion Polymerization

A direct emulsion process was performed for the synthesis of an emeraldine salt of polyaniline (PANI) us-ing a novel surfactant, namely cetyl dimethyl ammonium phenyl chloride (CDAPhCl). HCl was used as do-pant and potassium persulfate (KPS)was used as an oxidizing agent. Variation of polymer yield was recorded using conventional gravimetric method and resulting polymer salt was analyzed by FTIR. Average particle size and latex morphology was studied using dynamic light scattering (DLS) and scanning electron microsco-py (SEM).Furthermore, the influence of the reaction time followed by polymer yield on the conductivity of re-sulted PANI salt was investigated. SEM images showed a nanostructured polyaniline and conductivity of the polyaninle film found to be 1.65 S cm-1. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3563

A Soft Switched DC-DC Boost Converter for Use in Grid Connected Inverters

This paper presents a soft-switching DC-DC boost converter, which can be utilized in renewable energy systems such as photovoltaic array, and wind turbine connections to infinite bus of a big power network, using grid connected inverters. In the proposed topology for the DC-DC boost converter, the main and the auxiliary power switches are turned on and turned off with zero voltage switching (ZVS) and zero current switching (ZCS), respectively. Furthermore, by applying soft-switching techniques to driving power switches, the power losses and stresses associated with commutation of power devices decrease significantly. The efficiency of the proposed soft-switched DC-DC converter at various output powers is compared with that of the traditional DC-DC converter and a few topologies proposed in recent literature. This comparison indicates that the proposed DC-DC boost converter is much more efficient around the rated power (1 kW). The power topology and the control strategy applied to the proposed soft-switched DC-DC boost converter, which is connected to a grid-tied inverter, are analyzed theoretically by simulation studies. Moreover, an experimental prototype is implemented to verify the theoretical analysis and the simulation studies

Earthquake risk modeling for the evaluation of losses to property owners in the metropolitan area of Shiraz

Natural disasters can cause huge human and economic losses, and subsequent operation efforts in disaster relief, recovery and construction by the government, the private sector stakeholders as well as international donors can significantly drain their resources from other non-disaster related pre-planned investments. As a consequence, there is now a paradigm shift for dealing with extremes from after the event approaches to more pro-active ones, the later one including risk reduction and risk financing options. However, reliable and quantitative up-to-date estimation of the underlying risks is of outmost importance towards developing effective risk management strategies as well as risk reduction activities. This is even more so the case for countries that are highly exposed to natural hazards, such as earthquake risk in Iran. This paper focuses on earthquake risk for Shiraz, the 4th largest city in Iran located in a high seismic active hazard zone with high socio-economic and historical importance for the country. It is for the first time that such an assessment for the region is performed and therefore the results should shed some light on potential risks with a probability based setting which could guide current earthquake related policy processes in the region. A catastrophe modeling approach is adopted to assess risk and a detailed analysis of potential economic losses as well as vulnerability assessments for assets within district 1 is performed. Via combining the hazard, exposure and vulnerability an Exceedance Probability (EP) curve for assets as well as human losses are constructed. The EP curve represents a powerful tool for the assessment of feasible risk reduction strategies as well as cost-benefit analysis for these strategies. An approach is suggested how this could be achieved within an integrative framework

Risk management strategies for managing natural disaster risks: A case study in Shiraz City, Iran

Almost all parts of Iran are seismic hazard prone areas and due to the low quality of constructions as well the increase of exposure in urban areas, recent earthquake events caused unacceptable huge losses, both in human and economic terms. To assess the resilience of various risk bearers, including the government as well as private sector entities, the resources to cope with potential future events as well as possible interdependencies during the occurrence have to be analyzed in detail. Furthermore, to pro-actively act against possible future extremes with risk hedging instruments such as insurance, the underlying risk has to be determined in quantitative manner. This paper suggest how to combine both, the coping dimension as well as the risk dimension, to determine possible risk management strategies which may be feasible in the Iranian context. The focus is specifically on risk instruments, such as insurance, for the Shiraz region in Iran, where the newly produced probabilistic loss estimates are available which are subsequently used to analyze possible insurance schemes and for determining corresponding premium payments as well as affordability. The paper discusses how such risk instruments can be embedded within an integrated framework and which additional options, such as risk reduction or risk pooling, would be beneficial to lower premiums to affordable levels

Emergent properties of van der Waals bilayers revealed by computational stacking

Stacking of two-dimensional (2D) materials has emerged as a facile strategy for realising exotic quantum states of matter and engineering electronic properties. Yet, developments beyond the proof-of-principle level are impeded by the vast size of the configuration space defined by layer combinations and stacking orders. Here we employ a density functional theory (DFT) workflow to calculate interlayer binding energies of 8451 homobilayers created by stacking 1052 different monolayers in various configurations. Analysis of the stacking orders in 247 experimentally known van der Waals crystals is used to validate the workflow and determine the criteria for realizable bilayers. For the 2586 most stable bilayer systems, we calculate a range of electronic, magnetic, and vibrational properties, and explore general trends and anomalies. We identify an abundance of bistable bilayers with stacking order-dependent magnetic or electrical polarisation states making them candidates for slidetronics applications

Regional vulnerability of the hippocampus to repeated motor activity deprivation

Spontaneous vertical and horizontal exploratory movements are integral components of rodent behavior. Little is known, however, about the structural and functional consequences of restricted spontaneous exploration. Here, we report two experiments to probe whether restriction in vertical activity (rearing) in rats could induce neuro-hormonal and behavioral disturbances. Rearing movements in rats were deprived for 3 h/day for 30 consecutive days by placing the animal into a circular tunnel task. Rats temporarily deprived of rearing behavior showed elevated plasma corticosterone levels but no detectable psychological distress and/or anxiety-related behavior within an elevated plus maze. However, rats emitted a greater number of 22-kHz ultrasonic vocalizations and spent significantly more time vocalizing than controls when deprived of their rearing behavior. Despite intact spatial performance within wet- and dry-land spatial tasks, rearing-deprived rats also exhibited a significant alteration in search strategies within both spatial tasks along with reduced volume and neuron number in the hippocampal subregion CA2. These data suggest a new approach to test the importance of free exploratory behavior in endocrine and structural manifestations. The results support a central role of the CA2 in spontaneous exploratory behavior and vulnerability to psychological stress. © 2015 Elsevier B.V

A group-theoretic approach to the origin of chirality-induced spin selectivity in non-magnetic molecular junctions

Spin-orbit coupling gives rise to a range of spin-charge interconversion phenomena in non-magnetic systems where spatial symmetries are reduced or absent. Chirality-induced spin selectivity (CISS), a term that generically refers to a spin-dependent electron transfer in non-magnetic chiral systems, is one such case, appearing in a variety of seemingly unrelated situations ranging from inorganic materials to molecular devices. In particular, the origin of CISS in molecular junctions is a matter of an intense current debate. Here we contend that the necessary conditions for the CISS effect to appear can be generally and fully understood on the basis of a complete symmetry analysis of the molecular junction, and not only of the molecule. Our approach, which draws on the use of point-group symmetries within the scattering formalism for transport, shows that electrode symmetries are as important as those of the molecule when it comes to the emergence of a spin-polarization and, therefore, a possible appearance of CISS. It turns out that standalone metallic nanocontacts can exhibit spin-polarization when relative rotations are introduced which reduce the symmetry. As a corollary, molecular junctions with $\textbf{achiral}$ molecules can also exhibit spin polarization along the direction of transport, provided that the whole junction is chiral. This formalism also allows to predict the qualitative changes on the spin-polarization upon substitution of a chiral molecule in the junction with its enantiomeric partner. Quantum transport calculations based on density functional theory corroborate all of our predictions and provide further quantitative insight.Comment: 19 pages, 4 figures, 1 tabl

Laser-Beam-Patterned Topological Insulating States on Thin Semiconducting MoS2

Identifying the two-dimensional (2D) topological insulating (TI) state in new materials and its control are crucial aspects towards the development of voltage-controlled spintronic devices with low-power dissipation. Members of the 2D transition metal dichalcogenides have been recently predicted and experimentally reported as a new class of 2D TI materials, but in most cases edge conduction seems fragile and limited to the monolayer phase fabricated on specified substrates. Here, we realize the controlled patterning of the 1T′ phase embedded into the 2H phase of thin semiconducting molybdenum-disulfide by laser beam irradiation. Integer fractions of the quantum of resistance, the dependence on laser-irradiation conditions, magnetic field, and temperature, as well as the bulk gap observation by scanning tunneling spectroscopy and theoretical calculations indicate the presence of the quantum spin Hall phase in our patterned 1T′ phasesThe work carried out at Aoyama Gakuin University was partly supported by a grant for private universities and a Grant-in-Aid for Scientific Research (JP15K13277) awarded by MEXT. The work at the University of Tokyo was partly supported by Grantin-Aid for Scientific Research (JP17K05492, JP18H04218 and JP19H00652). J. J. P. and S. P. acknowledge Spanish MINECO through Grant No. FIS2016-80434-P, the Fundación Ramón Areces, the María de Maeztu Program for Units of Excellence in R&D (MDM-2014- 0377), the Comunidad Autónoma de Madrid through NANOMAGCOST Program, and the European Union Seventh Framework Programme under Grant Agreement No. 604391 Graphene Flagship. S. P. acknowledges the computer resources and assistance provided by the Centro de Computación Científica of the Universidad Autónoma de Madrid. S. P. was also supported by the VILLUM FONDEN via the Center of Excellence for Dirac Materials (Grant No. 11744). D. M. and E. G.-M. gratefully acknowledge support from the Graphene Flagship Graphene Core2 Contract No. 785219. E. G.-M also acknowledges IJCI-2017-32297 from Spanish MINECO/AE

Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media

In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application