Synthesis and characterization of low bandgap copolymers based on indenofluorene and thiophene derivative

A series of low band gap, highly soluble alternating conjugated copolymers, comprised of 11,11,12,12‐tetrahexylindenofluorene and thiophene derivatives ( P1‐P4 ), were synthesized via Pd‐catalyzed Suzuki coupling reaction with very good yields. Described here are the synthesis, thermal, optical, and electrochemical properties of these new copolymers as potential new active materials for electronic and optoelectronic device applications. P1 and P2 have electron donating non‐π‐substituents with ethylenedioxy and propylenedioxy bridging the 3,3 positions of the cyclopentadithiophene groups; whereas P3 and P4 have electron withdrawing π‐substituents (carbonyl and pyrazine groups on P3 and P4 , respectively). For the main absorptions in UV‐vis spectrum, P1 and P2 displayed more red absorptions in comparison with P3 and P4 . Nevertheless, much suppressed quantum yields are exhibited by P3 and P4 . The behaviors of P3 can be attributed to the significant charge transfer interactions between the π‐substituents and the conjugated polymer backbone that leads to a less allowed optical transition between the ground and the lowest excited state. For P4 , the weak fluoresence might associate with energy transfer from indenofluorene to the low band gap thiophene‐pyrazinethiophene‐thiophene (T‐PT‐T) unit. In comparison with the corresponding polymers containing fluorene instead of indenofluorene, the use of indenofluorene exhibited mixed effects on the optical properties and improved solubility. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5044–5056, 2009     

Convergence rates for rank-based models with applications to portfolio theory

We determine rates of convergence of rank-based interacting diffusions and semimartingale reflecting Brownian motions to equilibrium. Bounds on fluctuations of additive functionals are obtained using Transportation Cost-Information inequalities for Markov processes. We work out various applications to the rank-based abstract equity markets used in Stochastic Portfolio Theory. For example, we produce quantitative bounds, including constants, for fluctuations of market weights and occupation times of various ranks for individual coordinates. Another important application is the comparison of performance between symmetric functionally generated portfolios and the market portfolio. This produces estimates of probabilities of “beating the market”.     

The effect of extragent properties on the distribution of carboxylic acids

It has been established that the generalization of data on the distribution of carboxylic acids between organic and aqueous phases using the multiparameter linear free energy equations is preferential to using the London-Debye-Keesom potentials, which requires nonpolar and polar extragents to be examined separately. The formation of hydrogen bond between the components, which is determined by the basicity of an extragent, was shown to have an effect on the distribution value.     

Bis-chelate tetracarbene palladium(II) complex as an efficient and recyclable catalyst precursor for Heck reaction

A homoleptic Pd(II) complex with two chelating di-N-heterocyclic carbene (NHC) ligands has been synthesized and its square planar molecular geometry has been determined by X-ray diffraction analysis. The complex proved to be an efficient catalyst having exceedingly high turnover number and good reusability in Heck reaction.     

Experimental investigation of slosh dynamics of liquid-filled containers

This paper is concerned with the experimental studies on the sloshing response of liquid-filled containers. A three-dimensional finite element analysis is carried out for the numerical simulation of this problem. The effects of sloshing are computed in the time domain using Newmark's time integration scheme. A simple experimental setup is designed and fabricated in-house to conduct experiments for measuring some of the basic parameters of sloshing. A sensor device is especially developed to record the free-surface wave heights. Each wave height sensor is a capacitance probe that detects the change in level of liquid (water) precisely with no time lag. The sensors are used in conjunction with a signal-processing unit in which the capacitance values are transduced to a voltage signal between 0 V and 10 V. These wave height sensors simultaneously record the slosh wave height near the periphery of the container wall from 16 predetermined locations to give the free-surface profiles of liquid at desired time steps. The experimental results are compared with those obtained from the present theoretical analysis, and good agreements are observed.     

Reheating and leptogenesis in a SUGRA inspired brane inflation

We have studied extensively phenomenological implications in a specific model of brane inflation driven by background supergravity (Choudhury and Pal, 2011) [1], via thermal history of the universe and leptogenesis pertaining to the particle physics phenomenology of the early universe. Using the one loop corrected inflationary potential we have investigated for the analytical expression as well as the numerical estimation for brane reheating temperature for standard model particles. This results in some novel features of reheating from this type of inflation which have serious implications in the production of heavy Majorana neutrinos needed for leptogenesis through the reheating temperature. We have also derived the expressions for the gravitino abundance during reheating and radiation dominated era. We have further estimated different parameters at the epoch of phase transition and revealed their salient features. At the end we have explicitly given an estimate of the amount of CP violation through the effective CP phase which is related to baryon asymmetry as well as gravitino dark matter abundance.     

Optical communication fiber waveguide fabrication: A review

Abstract

The current state of the art in optical communication fiber waveguide fabrication is reviewed. Details of the two main technologies—multi-component glasses and high-silica glasses—are described, followed by brief details of other fiber fabrication techniques. The relative advantages and disadvantages of the different fiber fabrication techniques are discussed in the summary.     

Features of hydrolysis of phthalic acid chlorides

The experimentally measured rate constants of phthaloyl and terephthaloyl chlorides hydrolysis vary at the variable reagents ratio. This change obeys the Michaelis-Menten equation suggesting the intermediate formation by the reactants of the charge-transfer complex.