Non-equilibrium STLS approach to transport properties of single impurity Anderson model

In this work, using the non-equilibrium Keldysh formalism, we study the effects of the electron–electron interaction and the electron-spin correlation on the non-equilibrium Kondo effect and the transport properties of the symmetric single impurity Anderson model (SIAM) at zero temperature by generalizing the self-consistent method of Singwi, Tosi, Land, and Sjolander (STLS) for a single-band tight-binding model with Hubbard type interaction to out of equilibrium steady-states. We at first determine in a self-consistent manner the non-equilibrium spin correlation function, the effective Hubbard interaction, and the double-occupancy at the impurity site. Then, using the non-equilibrium STLS spin polarization function in the non-equilibrium formalism of the iterative perturbation theory (IPT) of Yosida and Yamada, and Horvatic and Zlatic, we compute the spectral density, the current–voltage characteristics and the differential conductance as functions of the applied bias and the strength of on-site Hubbard interaction. We compare our spectral densities at zero bias with the results of numerical renormalization group (NRG) and depict the effects of the electron–electron interaction and electron-spin correlation at the impurity site on the aforementioned properties by comparing our numerical result with the order U²$U^2$ IPT. Finally, we show that the obtained numerical results on the differential conductance have a quadratic universal scaling behavior and the resulting Kondo temperature shows an exponential behavior.     

Conformational flexibility, internal hydrogen bonding, and passive membrane permeability: successful in silico prediction of the relative permeabilities of cyclic peptides

We report an atomistic physical model for the passive membrane permeability of cyclic peptides. The computational modeling was performed in advance of the experiments and did not involve the use of "training data". The model explicitly treats the conformational flexibility of the peptides by extensive conformational sampling in low (membrane) and high (water) dielectric environments. The passive membrane permeabilities of 11 cyclic peptides were obtained experimentally using a parallel artificial membrane permeability assay (PAMPA) and showed a linear correlation with the computational results with R(2) = 0.96. In general, the results support the hypothesis, already well established in the literature, that the ability to form internal hydrogen bonds is critical for passive membrane permeability and can be the distinguishing factor among closely related compounds, such as those studied here. However, we have found that the number of internal hydrogen bonds that can form in the membrane and the solvent-exposed polar surface area correlate more poorly with PAMPA permeability than our model, which quantitatively estimates the solvation free energy losses upon moving from high-dielectric water to the low-dielectric interior of a membrane.     

Novel Efficient Circuit Design for Multilayer QCA RCA

The novel emerging technology, QCA technology, is a candidate for replacing CMOS technology. Full Adder (FA) circuits are also widely used circuits in arithmetic circuits design. In this paper, two new multilayer QCA architectures are presented: one-bit FA and 4-bit Ripple Carry Adder (RCA). The designed one-bit multilayer FA architecture is based on a new XOR gate architecture. The designed 4-bit multilayer QCA RCA is also developed based on the designed one-bit multilayer QCA FA. The functionality of the designed architectures are verified using QCADesigner tool. The results indicate that the designed architecture for 4-bit multilayer QCA RCA requires 5 clock phases, 125 QCA cells, and 0.17 μm² area. The comparison results confirm that the designed architectures provide improvements compared with other adder architectures in terms of cost, cell count, and area.

     

Graphite-lined capillary column for the separation of BTEX mixture and other volatile organic compoundc (VOCs)

Summary A very fast method for continous monitoring of BTEX compounds in different matrices is described. The use of a new graphite-lined (GLOT) capillary column, allows the complete separation of BTEX at isothermal conditions and very short analysis time. The same column is also able to separate polar compounds and other VOCs.     

A combined fatigue crack initiation and propagation specimen—its initial development

The investigation detailed in this paper involves the initial design and development of a specimen geometry, designated as a BN(T) specimen, that is suitable for the combined determination of: (a) the fatigue crack initiation; and (b) the fatigue crack propagation, characteristics of materials. The experimental procedure developed during the course of this investigation is applied to a Ti---6Al-4V titanium alloy. This crack initiation and propagation test involves the use of the BN(T) compact-tension specimen with a polished notch root that facilitates an in-situ replication technique for the detection of crack initiation, and a modification of the ASTM-E647 Standard for crack growth data acquisition. The stress intensity factors, K_I, associated with the BN(T) specimen are established in this paper by means of a numerical finite element investigation. The use of this unique specimen for fatigue testing gives very satisfactory results and its extended use is expected.     

Common set of weights in data envelopment analysis: a linear programming problem

Data Envelopment Analysis is used to determine the relative efficiency of Decision Making Units as the ratio of weighted sum of outputs by weighted sum of inputs. To accomplish the purpose, a DEA model calculates the weights of inputs and outputs of each DMU individually so that the highest efficiency can be estimated. Thus, the present study suggests an innovative method using a common set of weights leading to solving a linear programming problem. The method determines the efficiency score of all DMUs and rank them too.     

Time-resolved detection of melanin free radicals quenching reactive oxygen species

Melanin, a ubiquitous, heterogeneous biological polymer composed of many different monomers, contains a population of stationary, intrinsic semiquinone-like radicals. Additional extrinsic semiquinone-like radicals are reversibly photogenerated with visible or UV irradiation. The free radical chemistry of melanin is complex and not well characterized, especially the photochemistry of melanin in the presence of oxygen. To determine directly how melanin reacts in the presence of oxygen, time-resolved electron paramagnetic resonance (TREPR) spectroscopy was used to examine melanin free radical chemistry in human retinal pigment epithelium (RPE) cells under aerobic and anaerobic conditions. A TREPR difference spectrum was used to explore the nature of melanin chemistry in the presence of oxygen. The position and symmetrical line shape of the TREPR three-dimensional difference spectrum shows that when reactive oxygen species (ROS) are scavenged, only one of the two or more chemically different melanin free radical species participates in ROS scavenging. This protective melanin radical species exists in both the extrinsic and intrinsic populations of melanin free radicals, allowing melanin to protect the RPE from toxic species in both the light and dark.     

Finding strong defining hyperplanes of Production Possibility Set

Production Possibility Set (PPS) is defined as the set of all inputs and outputs of a system in which inputs can produce outputs. Data Envelopment Analysis models implicitly use PPS to evaluate relative efficiency of Decision Making Units (DMUs). Although DEA models can determine the efficiency of a DMU, they cannot present efficient frontiers of PPS. In this paper, we propose a method for finding all Strong Defining Hyperplanes of PPS (SDHP). They are equations that form efficient surfaces. These equations are useful in Sensitivity and Stability Analysis, the status of Returns to Scale of a DMU, incorporating performance information into the efficient frontier analysis and so on.     

Probabilistic mechanics of fibrous structures

In this paper the response behaviour of fibrous structures to a given uniaxial load is treated on the basis of probabilistic mechanics. For the illustration of the theoretical analysis, a cellulose network with specified properties is employed. The significant relations, which link the microscopic variables to the intermediate ones (mesoscopic) and thus to the macroscopic quantities are material functionals or operators. An operator for the given cellulose structure is derived in an explicit form. As a result of the analysis the internal stresses due to the given load are numerically evaluated.

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Zusammenfassung Das Verhalten einer Faserstruktur die einer axialen Belastung unterworfen ist, wird auf Grund der stochastischen Mechanik untersucht. Zur Veranschaulichung der theoretischen Behandlung wird eine zellulose Struktur mit spezifischen Eigenschaften benutzt. Die wichtigsten Relationen welche die mikroskopischen, dazwischen liegenden (mesoskopischen) und letzthin die makroskopischen Variablen verbindet, sind die Material-Operatoren. Es wird eine explizite Form eines solchen Operators für die zellulose Struktur abgeleitet. Die innere Spannungsverteilung, die wesentlich von der durchschnittlichen makroskopischen abweicht, wird sodann als ein Ergebnis der Untersuchung angezeigt.