固体高分辨~(13)C NMR研究γ线辐照对结晶聚乙稀聚集态结构的影响

结晶聚乙烯(PE)经~(60)Coγ线辐照后,用固体高分辨~(13)C NMR CP/DD/MAS方法观测解析了辐射效果与具有片晶结构的结晶相,结晶—橡胶状无定形界面相以及橡胶状无定形相的聚集态结构的关系。考察了各相中的~(13)C核自旋—晶格弛豫和自旋-自旋弛豫行为及辐照对其影响。得到辐照后产生交联,破坏,相转变及晶型变化等有意义的结果,对PE的辐照效应和机制的探讨提供了核磁共振的新实验证据。     

Effects of correlated Gaussian noise on the mean firing rate and correlations of an electrically coupled neuronal network

In this paper, we examine the effects of correlated Gaussian noise on a two-dimensional neuronal network that is locally modeled by the Rulkov map. More precisely, we study the effects of the noise correlation on the variations of the mean firing rate and the correlations among neurons versus the noise intensity. Via numerical simulations, we show that the mean firing rate can always be optimized at an intermediate noise intensity, irrespective of the noise correlation. On the other hand, variations of the population coherence with respect to the noise intensity are strongly influenced by the ratio between local and global Gaussian noisy inputs. Biological implications of our findings are also discussed.     

Travel time models for automated warehouses with aisle transferring storage and retrieval machine

This paper presents analytical travel time models for the computation of travel time for automated warehouses with the aisle transferring S/R machine (in continuation multi-aisle AS/RS). These models consider the operating characteristics of the storage and retrieval machine such as acceleration and deceleration and the maximum velocity. Assuming uniform distributed storage rack locations and pick aisles and using the probability theory, the expressions of the cumulative distribution functions with which the mean travel time is calculated, have been determined. The computational models enable the calculation of the mean travel time for the single and dual command cycles, from which the performance of multi-aisle AS/RS can be evaluated. A simulation model of multi-aisle AS/RS has been developed to compare the performances of the proposed analytical travel time models. The analyses show that regarding all examined types of multi-aisle AS/RS, the results of proposed analytical travel time models correlate with the results of simulation models of multi-aisle AS/RS.     

Improved induced matchings in sparse graphs

An induced matching in a graph G=(V,E) is a matching M such that (V,M) is an induced subgraph of G. Clearly, among two vertices with the same neighbourhood (called twins) at most one is matched in any induced matching, and if one of them is matched then there is another matching of the same size that matches the other vertex. Motivated by this, Kanj et al. [10] studied induced matchings in twinless graphs. They showed that any twinless planar graph contains an induced matching of size at least and that there are twinless planar graphs that do not contain an induced matching of size greater than . We improve both these bounds to , which is tight up to an additive constant. This implies that the problem of deciding whether a planar graph has an induced matching of size k has a kernel of size at most 28k. We also show for the first time that this problem is fixed parameter tractable for graphs of bounded arboricity.Kanj et al. also presented an algorithm which decides in -time whether an n-vertex planar graph contains an induced matching of size k. Our results improve the time complexity analysis of their algorithm. However, we also show a more efficient -time algorithm. Its main ingredient is a new, O^∗(4^l)-time algorithm for finding a maximum induced matching in a graph of branch width at most l.     

On Goulden-Jackson’s Determinantal Formula for the Immanant

In 1992, Goulden and Jackson found a beautiful determinantal expression for the immanant of a matrix. This paper proves the same result combinatorially. We also present a β-extension of the theorem and a simple determinantal expression for the irreducible characters of the symmetric group.     

The Epistemic Relevance of Morphological Content

Morphological content is information that is implicitly embodied in the standing structure of a cognitive system and is automatically accommodated during cognitive processing without first becoming explicit in consciousness. We maintain that much belief-formation in human cognition is essentially morphological: i.e., it draws heavily on large amounts of morphological content, and must do so in order to tractably accommodate the holistic evidential relevance of background information possessed by the cognitive agent. We also advocate a form of experiential evidentialism concerning epistemic justification—roughly, the view that the justification-status of an agent’s beliefs is fully determined by the character of the agent’s conscious experience. We have previously defended both the thesis that much belief-formation is essentially morphological, and also a version of evidentialism. Here we explain how experiential evidentialism can be smoothly and plausibly combined with the thesis that much of the cognitive processing that generates justified beliefs is essentially morphological. The leading idea is this: even though epistemically relevant morphological content does not become explicit in consciousness during the process of belief-generation, nevertheless such content does affect the overall character of conscious experience in an epistemically significant way: it is implicit in conscious experience, and is implicitly appreciated by the experiencing agent.     

Synaptic plasticity induced transition of spike propagation in neuronal networks

We investigate the impact of short-term plasticity on spike propagation in neuronal networks. We shown that for different combinations of the synaptic rise and decay time, neurons in the network exhibit a variety of different spike propagation transitions as the parameter related to the short-term plasticity increases. We establish the criteria for the existence and stability of simple and composite traveling waves, and we verify the analytical results by means of numerical simulations. Interestingly, we discover that the coexistence of simple and composite traveling waves, as well as the coexistence of stable and unstable waves is possible, provided only the short-term plasticity is properly set.     

Skew Pieri rules for Hall–Littlewood functions

We produce skew Pieri rules for Hall–Littlewood functions in the spirit of Assaf and McNamara (J. Comb. Theory Ser. A 118(1):277–290, 2011). The first two were conjectured by the first author (Konvalinka in J. Algebraic Comb. 35(4):519–545, 2012). The key ingredients in the proofs are a q-binomial identity for skew partitions and a Hopf algebraic identity that expands products of skew elements in terms of the coproduct and the antipode.     

The influence of repellent coatings on surface free energy of glass plate and cotton fabric

The aim of this research was to determine the influence of chemical finishes on the surface properties of glass plate, considered as a model homogeneous smooth surface and cotton fabric as a non-ideal heterogeneous rough surface. Microscopic slides and 100% cotton fabric in plain weave were coated with fluorocarbon polymers (FCP), paraffin waxes with zirconium salts (PWZ), methylolmelamine derivatives (MMD), polysiloxanes with side alkyldimethylammonium groups (PSAAC) and aminofunctional polysiloxanes (AFPS). From the goniometer contact angle measurements of different liquids, the surface free energy of the coated glass plates was calculated according to approaches by Owens-Wendt-Kaelble, Wu, van Oss-Chaudhury-Good, and Li-Neumann-Kwok. The results showed that all the coatings decreased the surface free energy of the substrate, which was also influenced by the liquid combination and the theoretical approach used. In spite of the fact that the liquid contact angles were much higher on the coated fabric samples than on glass plates and resulted in the lower values of work of adhesion, a very good correlation between the coatings deposited on both substrates was obtained. The presence of repellent coatings FCP, PWZ and MMD converted the solid surface from polar to highly apolar by masking the functional groups of glass and cellulose. PSAAC and AFPS coatings did not decrease the solid surface free energy to such an extent as the former three coatings due to their monopolar character.     

Conformational Effects of Regioisomeric Substitution on the Catalytic Activity of Copper/Calix[8]arene C−S Coupling

Functionalization of the phenolic rim of p-tert-butylcalix[8]arene with phenanthroline to create a cavity leads to formation of two regioisomers. Substitution of positions 1 and 5 produces the known C_2v-symmetric regioisomer 1,5-(2,9-dimethyl-1,10-phenanthroyl)-p-tert-butylcalix[8]arene ( L^1,5 ), while substitution of positions 1 and 4 produces the C_s-symmetric regioisomer 1,4-(2,9-dimethyl-1,10-phenanthroyl)-p-tert-butylcalix[8]arene ( L^1,4 ) described herein. [ Cu(L^1,4)I ] was synthesized from L^1,4 and CuI in good yield and characterized spectroscopically. To evaluate the effect of its cavity on catalysis, Ullmann-type C−S coupling was chosen as proof-of-concept. Selected aryl halides were used, and the results compared with the previously reported Cu(I)/ L^1,5 system. Only highly activated aryl halides generate the C−S coupling product in moderate yields with the Cu(I)/ L^1,4 system. To shed light on these observations, detailed computational investigations were carried out, revealing the influence of the calix[8]arene macrocyclic morphology on the accessible conformations. The L^1,4 regioisomer undergoes a deformation that does not occur with L^1,5 , resulting in an exposed catalytic center, presumably the cause of the low activity of the former system. The 1,4-connectivity was confirmed in the solid-state structure of the byproduct [ Cu(L^1,4 − H) (CH₃CN)₂] that features Cu(I) coordinated inside a cleft defined by the macrocyclic framework.