Structures and Energetics of NI3 and N2I4

We have applied new methods for performing coupled-cluster calculations to small molecules containing iodine atoms; specifically, NI₃ and N₂I₄. Because NI₃ is known to be very reactive, attempts to measure its thermodynamic properties have been challenging at best. To date, N₂I₄ has not been isolated, and our results suggest that its isolation will be just as challenging. We find that the ΔH_f(NI₃)=+307.7 kJ mol⁻¹ and ΔH_f(N₂I₄)=+551.6 kJ mol⁻¹, confirming that they are unstable with respect to their decomposition products N₂ and I₂.     

On Two-dimensional Predictions of Turbulent Cross-flow Induced Vibration: Forces on a Cylinder and Wake Interaction

In this paper a typical fluid-structure interaction scenario is investigated for a turbulent flow past a circular cylinder at a relatively low subcritical Reynolds number. Numerous experimental and numerical studies have been undertaken for a baseline Reynolds number of 4,000 involving a stationary cylinder to study in detail the near wake mean flow and turbulence characteristics. These studies conclusively show that the turbulent wake displays significant coherent periodic structures of large eddies that could be adequately and profitably resolved by “low order modelling” of turbulence. In this study, an unsteady numerical framework is employed for the simulations, incorporating an Arbitrary Lagrangian–Eulerian (ALE) method for the associated grid deformation to simulate the coupled motion of the circular cylinder with a single degree of freedom in the initial zone in a typical cylinder-flow response map or what is called “initial regime”. Particular attention is paid towards resolving the large scales of the fluid motion and the inherent coupling of the cylinder’s motion towards the associated evolution of the time averaged flow field. The flow-induced vibration effects regarding the kinetic energy exchange between the mean flow and the coherent periodic scales are investigated further. The predictions discussed and analyzed in detail in the paper display reasonable agreement with the chosen benchmark tests of the stationary cylinder and suggest that the conclusions outlined regarding the coupled flow-cylinder system potentially provides a valuable contribution to the state of the art.     

Orthogonal multifunctionalization of aliphatic polycarbonate via sequential Michael addition and radical‐thiol‐ene click reactions

Aliphatic polycarbonate (PC) copolymer is synthesized by ring opening copolymerization of acrylate‐ and allyl‐functional cyclic carbonate monomers. The post‐polymerization functionalization of the resulting copolymer is performed quantitatively using a variety of thiol compounds via sequential Michael addition and photo‐induced radical thiol‐ene click reactions within relatively short reaction time at ambient temperature. This metal‐free click chemistry methodology affords the synthesis of biocompatible PC copolymer with multifunctional groups. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1581–1587     

Hardy-Type Tauberian Conditions on Time Scales

Hardy’s well-known Tauberian theorem for number sequences states that if a sequence \(x=\left( x_{k}\right) \) satisfies \(\lim Cx=L\) and \(\Delta x_{k}:=x_{k+1}-x_{k}=O\left( 1/k\right) \), then \(\lim x=L\), where Cx denotes the Cesàro mean (arithmetic mean) of x. In this study, we extend this result to the theory of time scales. We also discuss the theory on some special time scales.     

A Bifunctional Photosensitizer for Enhanced Fractional Photodynamic Therapy: Singlet Oxygen Generation in the Presence and Absence of Light

The photosensitized generation of singlet oxygen within tumor tissues during photodynamic therapy (PDT) is self‐limiting, as the already low oxygen concentrations within tumors is further diminished during the process. In certain applications, to minimize photoinduced hypoxia the light is introduced intermittently (fractional PDT) to allow time for the replenishment of cellular oxygen. This condition extends the time required for effective therapy. Herein, we demonstrated that a photosensitizer with an additional 2‐pyridone module for trapping singlet oxygen would be useful in fractional PDT. Thus, in the light cycle, the endoperoxide of 2‐pyridone is generated along with singlet oxygen. In the dark cycle, the endoperoxide undergoes thermal cycloreversion to produce singlet oxygen, regenerating the 2‐pyridone module. As a result, the photodynamic process can continue in the dark as well as in the light cycles. Cell‐culture studies validated this working principle in vitro.     

Influence of ion implantation on structural and photoconductive properties of Bridgman grown GaSe single crystals

The structure and temperature dependent spectral photoconductivity of as‐grown and N‐and Si‐implanted GaSe single crystals have been studied. It was observed that post‐annealing results in a complete recovery of the crystalline nature that was moderately reduced upon implantation. The band edge is shifted in the implanted sample which is attributed to the structural modifications and continuous shallow levels introduced upon implantation and annealing. Our calculations showed that the trap density is increased upon implantation and annealing which confirms a possibility of explanation the phenomenon within a framework of continuous trap levels. Photocurrent measurements as a function of photo‐excitation intensity also support continuous distribution of localized states in the band gap. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

Mathematical modelling and the study of the influence of initial stresses on the SIF and ERR at the crack tips in a plate-strip of orthotropic material

A plate-strip fabricated from the orthotropic material and containing a crack whose edges are parallel to the face planes of the plate is considered. It is assumed that the strip is stretched (or compressed) initially along the crack edges by uniformly distributed external normal forces acting on the simply supported ends of the plate-strip. After this initial stretching (or compression) the crack edges are loaded by additional uniformly distributed normal (opening) forces. As a result of the action of these additional forces the stress concentration characterized by the stress intensity factor (SIF) of mode I or by the energy release rate (ERR) of mixed mode arises at the crack tips. In this paper, the influence of the initial stresses on the SIF or ERR is modelled mathematically by the use of the three-dimensional linearized theory of elasticity. The aim of the present investigations is to study the effect of the mechanical–orthotropic properties of the plate-strip material on this influence by the use of the finite element method (FEM) modelling of the corresponding boundary-value problem.     

The differential equations on time scales through impulsive differential equations

In this paper we investigate differential equations on certain time scales with transition conditions (DETC) on the basis of reduction to the impulsive differential equations (IDE). DETC are in some sense more general than dynamic equations on time scales [M. Bohner, A. Peterson, Dynamic equations on time scales, in: An Introduction With Applications, Birkhäuser Boston, Inc., Boston, MA, 2001, p. x+358; V. Laksmikantham, S. Sivasundaram, B. Kaymakcalan, Dynamical Systems on Measure Chains, in: Math. and its Appl., vol. 370, Kluwer Academic, Dordrecht, 1996]. The basic properties of linear systems, the existence and stability of periodic solutions, and almost periodic solutions are considered. Appropriate examples are given to illustrate the theory.     

Implementation of FPGA-based real time novel chaotic oscillator

Currently, chaotic systems and chaos-based applications are commonly used in the engineering fields. One of the main structures used in these applications is the chaos-based signal generators. Chaotic signal generators have an important role, particularly in chaotic communication and cryptology. In this study, the Pehlivan-Wei chaotic system, which is a recently developed chaotic system, has been implemented with FPGA using three distinct algorithms (the Euler, Heun, and RK4) for the first time in literature. Numerical and HDL approaches are implemented by these three algorithms to compare the performance of each model for use in chaotic generators. In addition, the Lyapunov exponents and phase portraits of the system have been extracted for chaos analysis. RMSE analysis has been conducted on the chaotic generators, which are modeled using the Euler, Heun, and RK4 algorithms in order to observe error rates of each numerical algorithm in a comparative aspect. The performance of new chaotic system with various data sets has been analyzed. The operation frequency of the chaotic oscillators synthesized and tested for the Virtex-6 FPGA chip has been able to reach up to 463.688 MHz and the chaotic system has been able to calculate 300,000 data sets in 0.0284 s. However, PC-based algorithm having highest performance score can calculate 300,000 data sets in a period of 75.363 s. A comparison study has been performed on the performance of the FPGA-based and PC-based solutions to evaluate each approach.