Cucurbit[n]urils-related Multitopic Supramolecular Components: Design,Properties, and Perspectives

Cucurbit[n]urils (CBns) are an intriguing family of macrocyclic hosts whose chemistry has undergone rapid developments in recent decades. The initial interest in the synthesis, modifications and binding properties has shifted to areas focused on applications in drug storage, delivery, and release, external-stimuli responsive devices, and molecular nano-reactors. Since CBns are fruitfully complemented by cyclodextrins (CDs) in such systems, guest molecules that contain several binding sites are needed. These multitopic guests provide not only a scaffold for holding CBns and CDs together in appropriate arrangements but also allow for manipulation with supramolecular aggregates, e. g., reorganization or release of macrocycles. In this review, we summarize recent studies related to the design of multitopic guests. Binding motifs properties, the role of attractive or repulsive lateral interactions, the competition-compensation effect, and rotaxane versus pseudorotaxane manner are discussed.     

Hierarchical structure of phase‐separated segmented polyurethane elastomers and its effect on properties

Polyurethanes were prepared from 4,4′‐methylenebis(phenyl isocyanate), 1,4‐butanediol and poly(1,4‐butanediol adipate) polyester polyol. The hydroxyl functional group ratio of polyol/total diol was kept constant at 0.4, while the ratio of the isocyanate and hydroxyl groups (NCO/OH ratio) changed between 0.90 and 1.15. The polymers were prepared by one‐step bulk polymerization in an internal mixer. They were characterized using a number of methods including Fourier transform infrared spectroscopy, wide‐ and small‐angle X‐ray scattering, differential scanning calorimetry, dynamic mechanical analysis, light transmittance and tensile testing. Changing the stoichiometry modifies the molecular weight in accordance with the laws of stepwise polymerization, and the relative concentration of end groups also changes at the same time. Competitive interactions among various groups including chain‐end functional groups lead to the formation of slightly ordered phases of sub‐nanometre size at both ends of the composition range. These structures assemble into larger units at the 10 nm level, which associate further to even larger entities of micrometre size causing scattering of light and a decreased transparency of the samples. The order of the primary units, together with the number and size of assemblies at both higher levels, decrease as the composition approaches equimolar stoichiometry. The amount of less ordered amorphous phase has a maximum in this range. The stiffness of the polymers is determined by the amount of this phase, while ultimate properties are influenced also by molecular weight and the number of physical crosslinks formed. Copyright © 2010 Society of Chemical Industry     

When Is the Ball Going to Hit the Ground? Duration Estimates, Eye Movements, and Mental Imagery of Object Motion.

Performance in 2 versions of a computer-animated task was compared. Participants either indicated the time of arrival of a target that rolled off a horizontal surface and fell--hidden from view--onto a landing point (production task) or judged flight time on a rating scale (judgment task). As predicted, performance was significantly better in the production task (Experiment 1), in which imagery of object motion probably replaced reasoning processes. Participants who exhibited eye movements suggesting mental tracking performed particularly well in the production task (Experimenl 2). There was, however, no decrement in performance when participants were asked to fixate the point where the target disappeared. For motion duration estimations, eye movements seem to be only a by-product of mental tracking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognizing Impossible Object Relations: Intuitions About Support in Chimpanzees (Pan troglodytes).

Using looking-time measures, the authors examined untrained chimpanzees' (Pan troglodytes) ability to distinguish between adequate and inadequate support. In 3 experiments, the chimpanzees' sensitivity to different support relations between 2 objects was assessed. In each experiment, the chimpanzees saw a possible and an impossible test event, presented as digital video clips. Looking times in the 3 experiments suggest that chimpanzees use amount of contact between 2 objects, but not type of contact, to distinguish between adequate and inadequate support relations. These results indicate that chimpanzees have some intuition about support phenomena but their sensitivity to relational object properties may differ from that of human infants (Homo sapiens) in this domain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A radiation-based approach to planar solid oxide fuel cell modules

This article describes the initial analysis underlying the design of a core module consisting of a 1 to 3 kW solid oxide fuel cell (SOFC) stack and a radiant air preheater (RAP) module. The design and testing of three SOFC stack/RAP modules was part of a California Energy Commission-sponsored project with the Gas Technology Institute. The objective of the design was to improve the thermal management of an SOFC system through radiant heat transfer from the stack walls to adjacent air preheater panels. The testing of this and subsequent modules has suggested that use of the radiation-based approach significantly improved the management of stack-generated heat. This paper was presented at the ASM Materials Solutions Conference & Show held October 18–21, 2004 in Columbus, OH.     

Immobilisation of pectinases into PVA gel for fruit juice application

In this study, for the first time, the use of polyvinyl alcohol gel in the form of LentiKats^® to immobilise pectinase was investigated and its application in fruit juice clarification was evaluated. Six pectolytic enzymes were tested for their polygalacturonase (PG) and pectin lyase (PL) activities. Panzyme YieldMASH and Panzyme Smash XXL exhibited maximum PG and PL activity, respectively (P < 0.05), in free and immobilised forms. The immobilised enzymes revealed a good adaptability to an acidic solution like fruit juice. Moreover, the immobilised Panzyme YieldMASH and Panzyme Smash XXL retained about 60% and 74% residual activity, respectively, in the second cycle and more than 30% during the third cycle. After that, both immobilised enzymes retained about 20% of their initial activity after repeating eight times without a significant decrease in the observed activity. The best result in terms of turbidity reduction was obtained in apple juice with immobilised Panzyme YieldMASH (about 80%), and the same % of turbidity reduction was successfully retained in the two following uses.     

Antiproliferative effects of prenylflavonoids from hops on human colon cancer cell lines

In recent years, interest in hop‐derived constituents, especially for prenylflavonoids has grown, as they have a wide range of biological properties including antioxidant, anticarcinogenic and antimicrobial activities. Two main hop prenylflavonoids, xanthohumol and isoxanthohumol, and hop extract enriched in prenylflavonoids, were tested for their antiproliferative activities on colon cancer cell lines, HT‐29 and SW620, and a noncancerous cell line, IEC‐6. It was confirmed that both xanthohumol and isoxanthohumol inhibited cell proliferation, even at micromolar concentrations. For cell line HT‐29, the IC₅₀ was 1.2 ± 0.9 and 16.9 ± 0.9 µmol dm^?3 for xanthohumol and isoxanthohumol, respectively. Similar values were obtained for SW620 cells (2.5 ± 0.2 and 37.3 ± 3.2 µmol dm^–3). None of the pure prenylflavonoids that were tested affected the proliferation of the noncancerous cell line, IEC‐6. The effect of the hop extract containing xanthohumol was also tested for antiproliferative activities on the cancer cell lines, HT‐29 (IC₅₀ = 3.1 ± 0.2 µmol dm^–3) and SW620 (IC₅₀ = 1 ± 0.2 µmol dm^?3), and on the cell line, IEC‐6 (IC₅₀ = 65.5 ± 11.3 µmol dm^?3). The results showed a similar trend to that for pure compounds, suggesting a possible future application of hop extracts in the pharmaceutical industry. Copyright © 2014 The Institute of Brewing & Distilling     

Cellular wave computer algorithms with spatial semantic embedding for handwritten text recognition

The recognition of cursive handwritten texts is a complex, in some cases unsolvable, task. One problem is that in most cases it is difficult or impossible to identify each letter, even if the words are separated. In our new method, the identification of letters is not needed due to the extensive and iterative use of semantic and morphological information of a given language. We are using a spatial feature code, generated by a cellular nonlinear network (CNN) based cellular wave computer algorithm, and combine it with the linguistic properties of the given language. Most general‐purpose handwriting recognition systems lack the ability to integrate linguistic background knowledge because they use it only for post‐processing recognition results. The high‐level a priori background knowledge is, however, crucial in human reading and similarly it can boost recognition rates dramatically in case of recognition systems. In our new system we do not treat the visual source as the only input: geometric and linguistic information are given equal importance. On the geometric side we use word‐level holistic feature detection without letter segmentation by analogic CNN algorithms designed for cellular wave computers (IEEE Trans. Circuits Syst. 1993; 40 :163–173; Cellular Neural Networks and Visual Computing, Foundations and Applications. Cambridge University Press: Cambridge, U.K., New York, 2002). The linguistic side is based on a morpho‐syntactic linguistic system (Proceedings of COLING‐2002, vol. II, Taipei, Taiwan, 2002; 1263–1267). A novel shape coding method is used to interface them, and their interaction is enhanced via an inverse filtering technique based on features that are global or of a low confidence value. A statistical context selection method is also applied to further reduce the output word lists. Copyright © 2008 John Wiley & Sons, Ltd.