Covalent fixed multicyclic polystyrene conformers

Covalent fixed multicyclic polystyrene conformers were synthesized from inconvertible polystyrene conformers based on p‐tert‐butylthiacalix[4]arene by azidation and subsequent click coupling. Selective 1D NOESY analyses confirmed that the spatial structures of star polystyrene precursors and multicyclic polystyrenes were preserved during the azidation and click coupling processes. The conformation of star polymers affected degree of decrease in the hydrodynamic volume after cyclization but had little effect on glass transition behavior. The rigid core of star polymer increased the T_g but in the case of multicyclic polymer, this influence of core structure was reduced. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 4020–4026     

Functional fuzzy clusterwise regression analysis

We propose a functional extension of fuzzy clusterwise regression, which estimates fuzzy memberships of clusters and regression coefficient functions for each cluster simultaneously. The proposed method permits dependent and/or predictor variables to be functional, varying over time, space, and other continua. The fuzzy memberships and clusterwise regression coefficient functions are estimated by minimizing an objective function that adopts a basis function expansion approach to approximating functional data. An alternating least squares algorithm is developed to minimize the objective function. We conduct simulation studies to demonstrate the superior performance of the proposed method compared to its non-functional counterpart and to examine the performance of various cluster validity measures for selecting the optimal number of clusters. We apply the proposed method to real datasets to illustrate the empirical usefulness of the proposed method.     

Chemical and morphological studies of plasma-treated integrated circuit bond pads

The effect of plasma treatment on the surface chemistry and morphology of Al-1%Si bond pads has been studied by a battery of analytical techniques. The ball shear strengths of the bond pads increased by ∼17% after CF₄ plasma treatment. The improvement in wire bondability after plasma treatment is largely attributed to a decrease in the oxide thickness and a reduction in the height of the crystallites on the bond pad surface. However, micro-pits were formed after CF₄ plasma treatment. The micro-pits become initiation sites of the first stage of a fluorine-induced corrosion where breakdown of the native passivating oxide occurs. In the second stage of corrosion, fresh Al beneath the oxide is exposed to the attack from the fluoride ions in the presence of water.     

Hydrothermal Realization of a Hierarchical,Flowerlike MnWO4@MWCNTs Nanocomposite with Enhanced Reversible Li Storage as a New Anode Material

A phase‐pure MnWO₄‐based nanocomposite, MnWO₄@MWCNTs (MWCNTs=multiwalled carbon nanotubes), was successfully synthesized through a simple hydrothermal reaction at 180 °C by adjusting the pH of the precursor medium. The resulting nanocomposite maintains the original flowerlike morphology of MnWO₄ with hierarchical structures composed of numerous single‐crystalline nanorods that drive growth preferentially along the [001] direction. The growth mechanism for the flowerlike formations is also discussed. In addition, the Li electroactivity of pure MnWO₄ and MnWO₄@MWCNTs electrodes was investigated. As an anode for Li‐ion batteries, the MnWO₄@MWCNTs nanocomposite showed enhanced electrochemical performance in reversible Li storage relative to that shown by bare MnWO₄ electrodes, including a high capacity of 425 mAh g^?1 and superior rate performance. This performance can be attributed to the synergistic effect of the nanocomposite combined with the MWCNTs, which provide efficient electron transport in their role as a conductor.     

Antiderivations on the exterior algebras

A matrix paraphrase of a certain body of facts dealing with real or complex numbers is a translation of these facts into matrix algebra in which the numbers are replaced by matrices. In two recent papers we developed matrix paraphrases of the Gaussian periods and the Klooster-mann sums. In this paper we paraphrase the theory of finite Fourier series and apply these results to Kloostermann matrices.     

Trading sensing coverage for an extended network lifetime

One of the main benefits of using Wireless Sensor Networks (WSNs) is that they can be deployed in remote locations without any prior infrastructure. Because of this nodes are normally battery powered. This limits the lifetime of the network. In this paper, we propose a novel method of scheduling nodes based on a user’s sensing coverage requirement. Through the use of our proposed scheduling algorithm (Ncut-GA), it is shown that the duration for which the user’s coverage requirement is met can be extended. When compared with a previously published algorithm (Greedy-MSC), the proposed algorithm is able to increase coverage duration by up to 80%. Furthermore it is also shown that the time until the first node dies can be improved by up to 200% through the use of Ncut-GA.     

Dispersion-induced power penalties in millimeter-wave signaltransmission using multisection DBR semiconductor laser

In this paper, we present a simple analytical model to characterize the effect of fiber chromatic dispersion when using a multisection distributed-Bragg reflector (DBR) semiconductor laser as a millimeter-wave optical transmitter in a millimeter-wave fiber-radio system. We characterize the dispersion penalty of the laser as a function of the laser operating conditions and establish that the penalty is dependent on the distribution of optical power among the modes in the laser output. This, in turn, is dependent on the spectrum-filtering property of the laser DBR section and the gain profile of the laser. In addition to the dispersion penalty, the stability of the generated millimeter-wave carrier from the multisection laser is investigated, including the detected RF power and resulting phase noise. We establish that a compromise must be made when finding the optimum bias condition of the laser which provides minimum dispersion penalty, maximum received RF power, and minimum phase noise of the generated millimeter-wave carrier