Modulation of optical and electronic properties of quinoxailine‐based conjugated polymers for organic photovoltaic cells

The synthesis of donor–acceptor type semiconducting copolymers is described. Quinoxaline (QX) or difluorinated quinoxaline (DFQX) derivatives serve as electron acceptors, while thiophene (T) or selenophene (Se) serve as electron donors. Alternating polymers are synthesized through Stille cross‐coupling, and their thermal stability, optical and electrochemical properties, field‐effect carrier mobilities, film crystallinities, and photovoltaic performances are investigated. The intramolecular charge transfer between the electron‐donating and electron‐accepting units in the backbone induces absorption from 450 to 750 nm. The optical band‐gap energies of the polymers are between 1.65 and 1.73 eV, and depend on the polymer structure. Organic photovoltaic cells fabricated using a polymer composed of DFQX and selenophene (PSe‐DFQX) exhibit a power conversion efficiency of 5.14% with an open‐circuit voltage of 0.78 V, a short‐circuit current density of 11.71 mA/cm², and fill factor of 0.57 under AM 1.5 G irradiation (100 mW cm^?2). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1904–1914     

Functional Limit Theorems for d-dimensional FBM in HSlder Norm

In this paper, we obtain functional limit theorems for d-dimensional FBM in HSlder norm via estimating large deviation probabilities for d-dimensional FBM in HSlder norm.     

Modeling and large sample estimation for multi-casting autoregression

Multi-casting autoregression (MCAR, for short) is suggested as a natural extension of the bifurcating autoregressive (BAR) model (cf. [Cowan, R., Staudte, R.G., 1986. The bifurcating autoregression model in cell lineage studies. Biometrics 42, 769–783]) in order to analyze multi-splitting tree-structured data. Pathwise stationarity of the MCAR model is discussed. Least squares estimation for the autoregressive parameter is considered and relevant limiting distribution is derived, in particular, for the pathwise explosive case. These results can be regarded as generalizations of those for standard stationary and explosive AR(1) time series. A simulation study is conducted to illustrate our results.     

A smeared / layered reinforced concrete model for finite element analysis

A new reinforced concrete model, in which the reinforcement steel is assumed as smeared / layered in concrete, is established and installed into a currently used finite element code for nonlinear analysis. It performs the nonlinear behaviors of both concrete and the reinforcement steel. The results of examples are in good agreement with the experimental data.     

Construction of BIB designs with various support sizes—with special emphasis for v = 8 and k = 4

This paper deals with methods of constructing new BIB designs from known designs. First, we provide a method of finding trades on a given BIB design so that new designs with the same parameters ν, b, k can be constructed. Second, we point out that the method of combining designs mentioned in [9] is particularly useful for constructing designs based on ν = 2k, k even, when designs based on ν = 2k ? 1 are available. By utilizing the above methods with the aid of Table I in [4], we have constructed a table of 53 BIB designs based on V = 8 and k = 4 with support sizes $\text{14 ? b 1 (}\text{8}\text{4}\text{)=70}$ except for $\text{b}{}^1\text{= 15, 16, 17, 19}$. BIB designs with ν = 8, k = 4 and $\text{b}{}^1\text{< 14}$ are shown to be nonexistent.     

The Mean-Partition Problem

In mean-partition problems the goal is to partition a finite set of elements, each associated with a d-vector, into p disjoint parts so as to optimize an objective, which depends on the averages of the vectors that are assigned to each of the parts. Each partition is then associated with a d × p matrix whose columns are the corresponding averages and a useful approach in studying the problem is to explore the mean-partition polytope, defined as the convex hull of the set of matrices associated with feasible partitions.     

The quenching of nucleon yields in the nonmesonic weak decay of Λ -hypernuclei and the three-body weak decay process

Recent exclusive coincidence measurements of non-mesonic weak decays (NMWD) reported for the ratio of the partial decay width of neutron-induced-to-proton-induced NMWD, Γ_n/Γ_p , values of 0.45±0.11±0.03 and 0.51±0.13±0.04 for 5lam and ¹² _Λ C , respectively. These observations agree well with the improved theoretical Γ_n/Γ_p ratios which are in the range of 0.3-0.7. It appears that the long-standing discrepancy between the experimental and theoretical values of Γ_n/Γ_p has finally been solved. However, when compared to the results of intra-nuclear cascade (INC) calculations, the observed numbers of both single nucleons and coincident nucleon pairs are strongly quenched. The quenching of the proton yield observed previously has been interpreted as an increase of the Γ_n/Γ_p ratio. On the other hand, significant contributions from the two-nucleon-induced three-body process ΛNN → nNN are predicted. Indeed, the angular correlation of the emitted nucleon pairs in the NMWD of ¹² _Λ C showed not only decay events in back-to-back kinematics, but also events with non-back-to-back kinematics. In this paper we show that the difficulties to extract the correct Γ_n/Γ_p ratio from the proton spectra is related to the three-body weak-interaction process which strongly quenches the nucleon yields.