Perovskite Photodiode for Wearable Electronics

Photodetectors are sensing devices that have been used for a broad range electromagnetic wave sensing applications. We are currently investigating the use of photovoltaic cells for implantable and wearable applications [1] [2]. In this work, we have demonstrated the use of CH3NH3PbI3-xClx perovskite materials for photo sensing applications in wearable electronic devices. Our photodetectors were fabricated from two different structures. The first involves the formation of a thin film perovskite material that is sandwiched between bottom and top contact electrodes, while the second involves using hole and electron transport layers between the bottom and top electrodes. Despite a poorer device stability, our experimental results confirmed that devices without an interlayer yield superior performance. Furthermore, AFM results show that the perovskite film formed on top of the PEDOT: PSS layer is non-uniform with more crystalline domains, while it has better surface coverage on top of bare ITO substrates [3] [4]

Fatty acid compositions and nutritional value of six walnut (Juglans regia L.) cultivars grown in Iran

Background and aims: Walnuts are good sources of polyunsaturated fatty acids (PUFA) and polyphenols which have beneficial effects such as proper growth, decreasing coronary heart disease, prevention of several kinds of cancer, anti-inflammatory and anti-mutagenic activities. In this study, the fatty acid content and antiradical activity of different walnut (Juglans regia L.) genotypes grown in Kolyaei region located in Kermanshah Province (Iran) were investigated. Methods: In this experimental study, fatty acid compositions in different genotypes of Persian walnut were determined using a GC–FID coupled with a flame ionization detector. For antiradical activity, methanolic extracts of different genotypes affected on DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical. BHA (2-tert-butyl-4-methoxyphenol) was used as the reference compound. Results: Total oil content of walnuts ranged from 63.3 to 78.5. Oleic acid, linoleic acid, linolenic acid, palmitic acid and stearic acid contents ranged respectively from 17.9 to 28.6, 46.9 to 56.8, 10.8 to 13.9, 5.5 to 7.2 and 2.0 to 3.9, while trace amounts of other fatty acids (<0.1 each) were detected in the samples. The results demonstrated that fatty acid composition is genotype dependent and the highest amounts of PUFA (due to the high content of linoleic acid) were observed in B2 genotype. Among different studied genotypes, the extract of B2 had also the highest radical scavenging activity and therefore the lowest EC50. Conclusion: It was concluded that pellicle is a necessary protecting layer that can help to inhibit the oxidation of fatty acids

Probing domain wall dynamics in magnetic Weyl semimetals via the non-linear anomalous Hall effect

The magnetic textures of Weyl semimetals are embedded into their topological structure and interact dynamically with it. Here, we examine electric field-induced structural phase transitions in domain walls mediated by the spin transfer torque, and their footprint in charge transport. Remarkably, domain wall dynamics lead to a transient, local, non-linear anomalous Hall effect and non-linear anomalous drift current, which serve as direct probes of the magnetization dynamics and of the domain wall location. We discuss experimental observation in state-of-the-art samples.Comment: 29 pages, 7 figure

Anomalous plasmon mode in strained Weyl semimetals

An exotic anomalous plasmon mode is found in strained Weyl semimetals utilizing the topological Landau Fermi liquid and chiral kinetic theories, in which quasiparticle interactions are modeled by long-range Coulomb and residual short-range interactions. The gapped collective mode is derived from the dynamical charge pumping between the bulk and the surface and behaves like $k_{\rm F}^{-1}$. The charge oscillations are accurately determined by the coupling between the induced electric field and the background pseudofields. This novel mode unidirectionally disperses along the pseudomagnetic field and manifests itself in an unusual thermal conductivity in apparent violation of the Wiedemann-Franz law. The excitation can be achieved experimentally by mechanical vibrations of the crystal lattice in the THz regime.Comment: 12 pages, 2 figures. To appear in Phys. Rev.

Wavelet-based Decomposition of Ground Acceleration for Efficient Calculation of Seismic Response in Elastoplastic Structures

The nonlinear dynamic analysis provides a more accurate simulation of the structural behavior against earthquakes. On the other hand, this analysis method is time-consuming since the time-step integration schemes are used to calculate the responses of the structure. Wavelet transform is also considered as one of the strong computing tools in studying the properties of the waves. The&nbsp;continuous wavelet transform is a time-frequency study and examines the frequency content of the waves while, the discrete wavelet transform is used to reduce sampling data and also to eliminate the noise of the waves. In this paper, the discrete and continuous wavelet transforms are used to reduce the wave sampling and therefore to reduce the required time for analysis. In this regard, eight near- and far- field earthquakes are studied. The frequency content of the earthquake is investigated by the Fourier spectrum and the continuous wavelet transform. The results show that the first five frequencies for the main earthquakes are similar to those values of earthquakes obtained by wavelet transform. Besides, it is shown that using wavelet transform for the main and decomposed earthquakes indicates that the duration of strong ground motion and the time of dominant frequency occur approximately in the same domain. Finally, it is concluded that the required calculation time reduces to about 80 % with an error less than 6 % when the main earthquake is decomposed by wavelet transform and the approximation waves are used in the nonlinear dynamic analysis

Infinitely many weak solutions for a fourth-order equation on the whole space

The existence of infinitely many weak solutions for a fourth-order equation on the whole space with a perturbed nonlinear term is investigated. Our approach is based on variational methods and critical point theory

Adaptive control design for a synchronous generator

The operating point of a power system changes to an unknown point with an unknown change in the mechanical input power. In this paper, a nonlinear adaptive controller is designed for excitation system of the generator based on the backstepping control technique, in order to achieve transient stability enhancement, in the presence of uncertainties in mechanical power. The designed controller guarantees the convergence of system states to new desired values corresponding to unknown mechanical power. A power system consisting of a synchronous generator connected to an infinite bus through a double circuit transmission line is used in control design and the simulation studies. Computer simulation verifies the effectiveness and the validity of the proposed control, considering faulted system with a clearance and change in network topology. © 2014, Editura Academiei Romane. All rights reserved