Compensation temperatures,magnetic susceptibilities and phase diagrams of a mixed ferrimagnetic ternary system on the Bethe lattice

Compensation behaviors, magnetic susceptibilities and the phase diagrams of the ternary system of the type ABC consisting of Ising spins σ = 1/2, S = 3/2 and m = 5/2 in the presence of a single-ion anisotropy are studied on the Bethe lattice within the framework of the exact recursion relations. Both ferromagnetic and antiferromagnetic exchange interactions are considered. The exact expressions for sublattice magnetizations and magnetic susceptibilities are obtained, and then thermal behaviors of the sublattice magnetizations, total magnetization, magnetic sublattice susceptibilities and total susceptibility are investigated. We find that the system only undergoes a second order phase transition for the different and same bilinear nearest-neighbor exchange interaction parameters, but displays compensation behaviors for only different bilinear interaction parameters. We also present the phase diagrams for the different and same bilinear nearest-neighbor exchange interaction parameters. A comparison is made with the other ternary system of the type ABC consisting of different spin values.     

Estimation of interfacial forces in time domain for linear systems

A structural path rank ordering process under transient excitations requires a good knowledge of the interfacial path forces, which are difficult to directly measure. Four time domain methods to estimate the interfacial forces are proposed and comparatively evaluated with application to linear time-invariant, proportionally damped discrete systems. First, the transient response is derived by modal analysis and a direct time domain technique to calculate the interfacial forces is outlined. Next, the frequency domain estimation methods, based on the sub-system concept are reviewed, and an inverse Fourier transform scheme is introduced. An indirect method of estimating interfacial force in transient state is then developed through an inverse procedure of modal analysis. The sub-system approach is employed to obtain the interfacial forces based on the forced vibration response of the original system and modal data of the sub-system. Finally, an approximate time domain scheme is suggested that could be used only if the system properties are known or precisely estimated. Although the proposed indirect methods are designed for eventual experimental applications, this article provides numerical feasibility studies via a simple source-path-receiver system (with parallel vibration paths) that has five translational degrees of freedom. The proposed methods are compared under ideal impulse force excitation input and a periodic sawtooth load (without and with Gaussian noise) to observe the starting transients as well as subsequent motions and interfacial forces. Preliminary comparisons with a laboratory experiment are very promising.     

Experimental and numerical study of omega type bianisotropic metamaterials combined with a negative permittivity medium

We report on the transmission properties of the omega (Ω) type metamaterials. Transmission through the periodic Ω-only and Ω-wire metamaterials are studied experimentally and numerically. A resonance band gap is observed for the periodic Ω medium around the resonance frequency of the single Ω unit cell. A transmission band is observed below the resonance band gap, when the periodic Ω structure is embedded in a negative permittivity medium composed of thin metallic wire arrays. We also studied the effect of periodicity on the transmission spectra of Ω type metamaterials.     

The importance of the series resistance in calculating the characteristic parameters of the Schottky contacts

Cd/p-Si Schottky barrier diodes (SBDs) with and without the native oxide layer have been fabricated to determine the importance of the fact that the series resistance value is considered in calculating the interface state density distribution (ISDD) from the forward bias current-voltage (I-V) characteristics of the Cd/p-Si SBDs. The statistical analysis yielded mean values of 0.71 ± 0.02 eV and 1.24 ± 0.12 for the BH and ideality factor of the Cd/p-Si SBDs (15 dots) without the native oxide layer (MS), respectively, and mean values of 0.79 ± 0.02 eV and 1.36 ± 0.06 eV for the Cd/p-Si SBDs (28 dots) with the native oxide layer (metal-insulating layer-semiconductor (MIS)). The interface state density (Nss) distributions of the devices were calculated taking into account their series resistance values. At the same energy position near the top of the valence band, the interface state density values without taking into account the series resistance value of the devices are almost one order of magnitude larger than Nss obtained taking into account series resistance value.     

On positive solutions for a nonlinear boundary value problem with impulse

In this paper we study nonlinear second order differential equations subject to separated linear boundary conditions and to linear impulse conditions. Sign properties of an associated Green’s function are investigated and existence results for positive solutions of the nonlinear boundary value problem with impulse are established. Upper and lower bounds for positive solutions are also given.     

Torus Knots and Dunwoody Manifolds

We obtain an explicit representation as Dunwoody manifolds of all cyclic branched coverings of torus knots of type (p,mp±1), with p > 1 and m > 0.     

A numerical approach to solve the model of an electromechanical system

In this paper, the model of an electromechanical system, which is a system of linear differential equations, is studied. Haar wavelet collocation method (HWCM) is applied for finding the approximate solution of the model. HWCM reduces the system of the model into a matrix‐vector form that contains the unknown Haar coefficients, and these coefficients are easily calculated. To demonstrate the validity and applicability of HWCM, numerical solutions of the system for different parameter values in the system are presented. The obtained results demonstrate the efficiency and accuracy of the method. All of the computations are performed via a program written in Mathematica.     

Additive manufacturing and biomechanical validation of a patient‐specific diabetic insole

Centers for Disease Control and Prevention (CDC) has reported that lower extremity amputation (LEA) rate of per 1000 diabetic patients is 18.4 because of the complications that first appeared in the foot. A second amputation is also required for 9% to 17% of these patients within the same year although LEA may be preventable. Most of the diabetic foot conditions may be prevented and treated by a therapeutic footwear or a medical device such as an insole or an orthotic shoe. Traditional insole manufacturing is a laborious work that requires specific skills. Moreover, traditional approaches contain harmful material particles that may cause respiratory failure. Unfortunately, manufactured insoles may not be suitable for any mass‐produced footwear in all cases. Therefore, patient requires to get insole‐specific footwear. In this study, a diabetic insole was manufactured by means of a fused deposition modeling‐(FDM) based system and a thermoplastic polymer. Biomechanical functionality was determined according to the applied polymer analysis on each produced sample and foam material. Subsequently, finite element analysis (FEA) was performed to target insole geometry to ensure the quality of the final medical product. Additive and traditional manufactured insoles are compared according to the cost and function. As a result, fabrication of an insole, based on the FDM method, was improved down to 8 h and 9 m. The weight of an insole prototype was 74.74 g, and the material cost was $3.44 while total cost of the traditional foam casting was determined as $35.37 and weight of the insole was 72.6 g for this study. Consequently, benefits of the applied method are evaluated.     

A universal self‐eroding sacrificial bioink that enables bioprinting at room temperature

Natural polymer‐based hydrogel bioinks are widely used in bioprinting due to their suitability for recapitulation of in vivo cellular activities. However, preservation of the target geometry in a cell‐laden hydrogel is difficult to achieve. The aim of this study was to develop a universal sacrificial bioink that allows high cell viability and a better shape fidelity in the cell‐laden construct. A polysaccharide‐based universal sacrificial bioink was developed for microextrusion‐based bioprinting and was optimized to erode in 48 hours in the cell culture medium without formation of any undesired by‐products. The sacrificial hydrogel was prepared from alginate and agarose via a microwave oven assisted method and bioprinted at room temperature to generate microchannels in the cell‐laden hydrogel or to support a tubular structure and its biocompatibility determined by live/dead assay. Bioprinting time was significantly reduced, down to a few minutes for a large‐scale tissue model (1 minute 52 seconds for a 2 cm tubular structure), by means of a high bioprinting speed up to 25 mm/s. After 48 hours in the cell culture, the sacrificial bioink completely detached from the cell‐laden construct without causing any changes in its printed shape. Cell viability in the cell‐laden construct was observed to be more than 95% at the end of 3‐day culture. This novel sacrificial bioink enables bioprinting at room temperature without affecting oxygen and nutrient penetration into the cell‐laden hydrogel and allows retention of high cell viability and shape fidelity.