Item and order information in subject-performed tasks and experimenter-performed tasks.

This study investigated the enactment effect from the perspective of the item-order hypothesis (e.g., M. Serra & J. S. Naime, 1993). The authors assumed that in subject-performed tasks (SPTs), item encoding is improved but order encoding is disrupted compared with experimenter-performed tasks (EPTs), that order encoding of EPTs is only better in pure lists, and that the item-order hypothesis is confined to short lists. Item information was tested in recognition memory tests, order information in order reconstruction tasks, and both item and order information in free-recall tests. The results of 5 experiments using short (8 items) and long lists (24 items) in a design with list type (pure, mixed) and encoding condition (EPT, SPT) as factors supported the hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pop-out into memory: A retrieval mechanism that is enhanced with the recall of subject-performed tasks.

Subject-performed tasks (SPTs; i.e., carrying out the actions during study) improve free recall of action phrases without enhancing relational information. By this mechanism, items pop into a person's mind without active search, and this process especially extends the recency effect. The authors demonstrated the existence of the extended recency effect and its importance for the SPT recall advantage (Experiments 1 and 2). Carrying out the action and not semantic processing caused the effect (Experiment 3). The extended recency effect was also not a consequence of a deliberate last-in, first-out strategy (Experiment 4), and performing a difficult secondary task (an arithmetic task) during recall reduced memory performances but did not influence the extended recency effect (Experiment 5). These data support the theory that performing actions during study enhances the efficiency of an automatic pop-out mechanism in free recall. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A virus-based single-enzyme nanoreactor

Most enzyme studies are carried out in bulk aqueous solution, at the so-called ensemble level, but more recently studies have appeared in which enzyme activity is measured at the level of a single molecule, revealing previously unseen properties. To this end, enzymes have been chemically or physically anchored to a surface, which is often disadvantageous because it may lead to denaturation. In a natural environment, enzymes are present in a confined reaction space, which inspired us to develop a generic method to carry out single-enzyme experiments in the restricted spatial environment of a virus capsid. We report here the incorporation of individual horseradish peroxidase enzymes in the inner cavity of a virus, and describe single-molecule studies on their enzymatic behaviour. These show that the virus capsid is permeable for substrate and product and that this permeability can be altered by changing pH.     

Magnetic Fields as an Investigation Technique and Manipulation Tool for Phthalocyanine Molecular Aggregates

A polarized absorption spectroscopy (PAS) study of molecular aggregate solutions of phthalocyanine molecules in high magnetic fields is presented. We show that a magnetic field can induce macroscopic ordering of molecular aggregates (MAs), in a clean, non‐contact method, which is well suited for MA manipulation. We also demonstrate that magnetic‐field‐induced alignment in combination with PAS can be used to determine the MA size and the precise position of the absorption lines in concentrated solutions, as well as probe interaggregate interactions.     

Categorical-relational and order-relational information in memory for subject-performed and experimenter-performed actions.

Memory for self-performed tasks (SPTs) is better than memory for experimenter-performed tasks (EPTs). In short unrelated lists of actions this effect occurs if the encoding condition is manipulated within subjects. In a between-subjects design, the enactment effect disappears (J. Engelkamp & D. Dehn, 2000; J. Engelkamp & H. D. Zimmer, 1997). These findings were explained by the item-order hypothesis, which claims that encoding order information depends on the type of encoding and design. The authors demonstrate that this differential encoding of order information in EPTs and SPTs is not effective in free recall if categorized lists are used. The use of categorized lists makes the interaction of type of encoding and design in free recall of short lists disappear, and the enactment effect reappears independent of the type of design. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inside Front Cover: Self‐Organization of Semiconducting Polysiloxane‐Phthalocyanine on a Graphite Surface (Adv. Mater. 10/2005)

Helical phthalocyaninato–polysiloxanes (PSPcs) can self‐organize at surfaces into highly ordered, rod‐like structures with a molecular cross‐section, as is shown schematically on the inside cover and reported by Samori and co‐workers on p. 1265. The inset is a scanning force microscopy image depicting experimentally obtained molecular cylinders with lengths in the range of hundreds of nanometers. The micrometers‐long cylinders so formed have high apparent stiffness and are good candidates for nanoscale photophysics and electronics applications.     

A virus-based biocatalyst

Virus particles are probably the most precisely defined nanometre-sized objects that can be formed by protein self-assembly. Although their natural function is the storage and transport of genetic material, they have more recently been applied as scaffolds for mineralization and as containers for the encapsulation of inorganic compounds. The reproductive power of viruses has been used to develop versatile analytical methods, such as phage display, for the selection and identification of (bio)active compounds. To date, the combined use of self-assembly and reproduction has not been used for the construction of catalytic systems. Here we describe a self-assembled system based on a plant virus that has its coat protein genetically modified to provide it with a lipase enzyme. Using single-object and bulk catalytic studies, we prove that the virus-anchored lipase molecules are catalytically active. This anchored biocatalyst, unlike man-made supported catalysts, has the capability to reproduce itself in vivo, generating many independent catalytically active copies.     

The role of item-specific information for the serial position curve in free recall.

The serial position curve in free recall of a list of action phrases differs depending on whether the phrases were memorized by listening/reading (verbal task; VT) or by additionally enacting the denoted actions (subject-performed task; SPT). In VTs there is a clear primacy effect and a short recency effect. In SPTs there is no primacy effect but an extended recency effect. H. D. Zimmer, T. Helstrup, and J. Engelkamp (2000) assumed that SPTs provide excellent item-specific information, which leads to an automatic pop-out of the items presented last. In the present study, the authors assumed that good item-specific encoding generally enhances the recency effect and that it hinders rehearsal processes and thereby reduces the primacy effect. This assumption was confirmed. An item-specific orienting task leads to parallel serial position curves in VTs and SPTs with no primacy effect but a clear recency effect. Moreover, the same serial position effects were shown with nouns as learning material. An item-specific orienting task changes the classical U-shaped serial position curve with verbal material and leads to the disappearance of the primacy and the enhancement of the recency effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparation of Biomolecule Microstructures and Microarrays by Thiol–ene Photoimmobilization

A mild, fast and flexible method for photoimmobilization of biomolecules based on the light‐initiated thiol–ene reaction has been developed. After investigation and optimization of various surface materials, surface chemistries and reaction parameters, microstructures and microarrays of biotin, oligonucleotides, peptides, and MUC1 tandem repeat glycopeptides were prepared with this photoimmobilization method. Furthermore, MUC1 tandem repeat glycopeptide microarrays were successfully used to probe antibodies in mouse serum obtained from vaccinated mice. Dimensions of biomolecule microstructures were shown to be freely controllable through photolithographic techniques, and features down to 5 μm in size covering an area of up to 75×25 mm were created. Use of a confocal laser microscope with a UV laser as UV‐light source enabled further reduction of biotin feature size opening access to nanostructured biochips.