Narrow Results

As a suitable recombination process, recombination via tail state in organic bulk-heterojunction solar cells (OBHJs) is capable of reproducing both dark and illuminated current–voltage curves. The characteristic parameters of OBHJs based on recombination via tail are governed by transportation and extraction efficiency, and both processes are strongly dependent on the charge carrier mobility. Using a macroscopic simulation, we calculate the mobility dependent power conversion efficiency, open-circuit voltage, short-circuit current and fill factor. The open-circuit voltage is determined by not only carrier density n(p), but also by carrier density gradient. Furthermore, open-circuit voltage is more affected by majority charge carriers and less affected by minority ones.

A (commutative unital) ring is said to have FSP if it has only finitely many unital subrings. The singly generated rings that have FSP have been classified. Thus, a characterization of the rings satisfying FSP is obtained by proving that a ring R has FSP if and only if either R is finite or R = ℤ[t₁, …, t_n] ⊇ ℤ where ℤ[t_i] has FSP for each i = 1, …, n. Also, the following characterization is given for the nontrivial ring direct products Π_{i ∈ I} R_i that have FSP: I is finite, each R_i has FSP, and there is at most one i ∈ I such that R_i has characteristic 0.

If $A\subseteq B$ are (commutative) rings, $[A,B]$ denotes the set of intermediate rings and $(A,B)$ is called an almost valuation (AV)-ring pair if each element of $[A,B]$ is an AV-ring. Many results on AV-domains and their pairs are generalized to the ring-theoretic setting. Let $R\subseteq S$ be rings, with ${\overline{R}}_S$ denoting the integral closure of $R$ in $S$. Then $(R,S)$ is an AV-ring pair if and only if both $(R,{\overline{R}}_S)$ and $({\overline{R}}_S,S)$ are AV-ring pairs. Characterizations are given for the AV-ring pairs arising from integrally closed (respectively, integral; respectively, minimal) ring extensions $R\subseteq S$. If $(R,S)$ is an AV-ring pair, then $R\subseteq S$ is a P-extension. The AV-ring pairs $(R,S)$ arising from root extensions are studied extensively. Transfer results for the “AV-ring” property are obtained for pullbacks of $(B,I,D)$ type, with applications to pseudo-valuation domains, integral minimal ring extensions, and integrally closed maximal non-AV subrings. Several sufficient conditions are given for $(R,S)$ being an AV-ring pair to entail that $S$ is an overring of $R$, but there exist domain-theoretic counter-examples to such a conclusion in general. If $(R,S)$ is an AV-ring pair and $R\subseteq S$ satisfies FCP, then each intermediate ring either contains or is contained in ${\overline{R}}_S$. While all AV-rings are quasi-local going-down rings, examples in positive characteristic show that an AV-domain need not be a divided domain or a universally going-down domain.

Jacobson investigated the structure of rings with the property that some power of each element is central, in the procedure of the study of commutativity. In this paper, we consider a class of rings in which this property occurs only for central elements, and such rings are called ppnc. We first prove that a noncommutative ppnc ring is infinite, and that a ppnc ring is commutative when it is a K-ring or a locally finite ring. We next study the structure of ppnc rings, and the relation between ppnc rings and related concepts (for example, K-rings, commutative rings and NI rings), through matrix rings, polynomial rings, right quotient rings and direct products.

In this paper, we investigate overdetermined systems of scalar PDEs on the plane with one common characteristic, whose general solution depends on one function of one variable. We describe linearization of such systems and their integration via Laplace transformation, relating this to Lie's integration theorem and formal theory of PDEs.

In this paper we investigate compatible overdetermined systems of PDEs on the plane with one common characteristic. Lie's theorem states that its integration is equivalent to a system of ODEs, and we give a new proof by relating it to the geometry of rank 2 distributions. We find a criterion for integration in quadratures and in closed form, and discuss nonlinear Laplace transformations and symmetric PDE models.

The sustainable innovation in the supply chain has been considered as an effective way to face the challenge of resource shortage and help organizations build the competitive advantage. However, the understanding on the characteristics of sustainable supply chain innovation (SSCI) still remains unclear. This study aims to explore and identify the characteristics of SSCI by examining a case of YHD, the first and major online retail enterprise in China. The findings of this case identify the characteristics of SSCI in seven dimensions. It emphasizes that SSCI can be generated at interfaces among supply chain participants in the network covering various innovation types. This case helps organizations to better manage and allocate resources to support their SSCI. Further, this case also informs us about the two interacted phases of SSCI.

Graphene as a new carbon material allotropism body has many unique properties. The material structure of graphene is a two-dimensional crystal structure with carbon atom superposition in monolayer mode. This special structures exhibit many unique physical and chemical properties, etc. This paper introduced the special physical and chemical properties of graphene, and reviewed the research progress and applications of graphene in the high-tech fields.