Most and Least Preferred Colours Differ According to Object Context: New Insights from an Unrestricted Colour Range

Humans like some colours and dislike others, but which particular colours and why remains to be understood. Empirical studies on colour preferences generally targeted most preferred colours, but rarely least preferred (disliked) colours. In addition, findings are often based on general colour preferences leaving open the question whether results generalise to specific objects. Here, 88 participants selected the colours they preferred most and least for three context conditions (general, interior walls, t-shirt) using a high-precision colour picker. Participants also indicated whether they associated their colour choice to a valenced object or concept. The chosen colours varied widely between individuals and contexts and so did the reasons for their choices. Consistent patterns also emerged, as most preferred colours in general were more chromatic, while for walls they were lighter and for t-shirts they were darker and less chromatic compared to least preferred colours. This meant that general colour preferences could not explain object specific colour preferences. Measures of the selection process further revealed that, compared to most preferred colours, least preferred colours were chosen more quickly and were less often linked to valenced objects or concepts. The high intra- and inter-individual variability in this and previous reports furthers our understanding that colour preferences are determined by subjective experiences and that most and least preferred colours are not processed equally.     

Soluble Combinatorial Libraries: Extending the Range and Repertoire of Chemical Diversity

The generation and use of libraries made up of millions of chemical entities and the ability to identify the active compound in such libraries are at the forefront of a revolution in drug discovery and basic research. Such libraries, when made up of peptide sequences, offer a fundamental, practical advance in the study of interactions between peptides and their biochemical or pharmacological targets. The utility of soluble peptide libraries ranging from three to eight amino acids in length, and made up of mixtures from 361 tripeptides to 200 billion decapeptides, is described. These are readily usable in virtually all in vitro (and even in vivo) assay systems. The examples presented illustrate the utility of soluble peptide libraries for the study of antibody/antigen interactions, the identification of highly active opioid peptides in receptor binding studies using crude rat brain homogenates, and in vivo studies, in which the peptide mixtures making up the library are administered intravenously to determine peptide sequences that affect heart rate and blood pressure. A new class of library is also described, termed a modified peptide library, which is used to determine potent anti-Staphylococcus aureus compounds.     

The Relation of Signal Transduction to the Sensitivity and Dynamic Range of Bacterial Chemotaxis

Complex networks of interacting molecular components of living cells are responsible for many important processes, such as signal processing and transduction. An important challenge is to understand how the individual properties of these molecular interactions and biochemical transformations determine the system-level properties of biological functions. Here, we address the issue of the accuracy of signal transduction performed by a bacterial chemotaxis system. The chemotaxis sensitivity of bacteria to a chemoattractant gradient has been measured experimentally from bacterial aggregation in a chemoattractant-containing capillary. The observed precision of the chemotaxis depended on environmental conditions such as the concentration and molecular makeup of the chemoattractant. In a quantitative model, we derived the chemotactic response function, which is essential to describing the signal transduction process involved in bacterial chemotaxis. In the presence of a gradient, an analytical solution is derived that reveals connections between the chemotaxis sensitivity and the characteristics of the signaling system, such as reaction rates. These biochemical parameters are integrated into two system-level parameters: one characterizes the efficiency of gradient sensing, and the other is related to the dynamic range of chemotaxis. Thus, our approach explains how a particular signal transduction property affects the system-level performance of bacterial chemotaxis. We further show that the two parameters can be derived from published experimental data from a capillary assay, which successfully characterizes the performance of bacterial chemotaxis.     

Modern Approaches to Chemical Modification of Proteins in Biological Tissues: Consequences and Application

Products made of biomaterials, such as heart valve prostheses, vascular grafts, and patches for vascular and intracardiac plastics, are currently used in cardiovascular surgery. The biological tissue used for prosthetics is the alternation of transverse and longitudinal layers of collagen fibers consisting of type I collagen (75%), elastin (<5%), cell elements, as well as glycoproteins, glycosaminoglycans, and other components of the cell matrix. Chemical modifications of components of a biological tissue allow for retention of its natural architectonics and stability of collagen structure over time, while simultaneously increasing the collagen resistance to enzymatic and mechanical destruction and preventing cellular and immune effects on the part of the recipient organism. Proteins in biological tissues are chemically modified (preserved) by the formation of intramolecular and intermolecular cross-links between the amino groups of amino acid residues in collagen molecules. However, cross-linking increases the calcification of biomaterial, making the tissue more rigid and leading to the rupture of the valve flaps, stenosis (reduced clearance), or insufficiency (a decrease in the closure function) of the heart valves. Calcification can also result from specific physiological features of recipient (the patient who received the artificial organ), the nature of the preserving agent, components of the dead cells, defects of collagen structure, cavities in tissues, and the presence of lipids, elastin fibers, glycosaminoglycans, and so on. The factors that induce calcification of the materials used for prosthetic repair and the corresponding methods for its prevention are reviewed. All methods are conventionally divided into three groups: chemical pretreatment of tissues, modification of the preservation method, and posttreatment of preserved tissues with chemical agents. The mechanisms of the processes underlying the effect of chemical agents on the structures of biological tissues are described. The results of their use in clinical practice and prospects for methods still under development and in preclinical trials are discussed, as well as the reasons why some methods have failed. The advantages and disadvantages of various types of treatments are considered. Variants of new methods for chemical modification of biological materials potentially effective in reducing the risk of calcification are proposed.     

Wet Chemical Colorimetric Estimation of CO: An Update on the Reduced Silver Sol Spectral and Kinetic Transformations to Silver nanoparticle

Measurements of ppm (v/v) level CO_g concentration is conveniently performed by its preconcentration in alkaline absorber solution of Ag⁺-(4)- HCO₂-C₆H₄-SO₂NH₂ complex, followed by a spectral measurement of the reduced silver sol. In this study, the transitory nature of this latter species and its subsequent real-time transformation to silver nanoparticle are presented. These results were based on spectral measurements made under varying concentrations of alkali, (4)-HCO₂-C₆H₄-SO₂NH₂, and Ag⁺ in the absorber solution, and in the presence of a wide range of sampled CO_g concentration. The initially created light yellow colored sol with its broad absorption profile peaking at 380 nm and absorption coefficient 3500?±?300 cm^?1 M^?1 (related to the amount of sampled [CO_g] as standardized by gas chromatographic analysis) changed into the characteristic yellow orange nanoparticle with its plasmon band peak absorption at 425 nm and absorption coefficient 6350?±?300 cm^?1 M^?1. Under different sampling conditions, the respective first-order conversion rates varied between 0.03 and 0.15 h^?1, whereas simultaneous dynamic light scattering measurements revealed steady growth of the averaged particle size ranging from 60 to 300 nm.     

Anthocyanins and their distribution in the genusEpimedium

Anthocyanins contained in plants belonging to the genusEpimedium in Japan are discussed in this study. Two kinds of anthocyanin, delphinidin 3-p-coumaroyl-sophoroside-5-glucoside (cayratinin) and cyanidin 3-p-coumaroylsophoroside, were identified, and the latter is new to the literature. Only cayratinin was found in the colored petals of theEpimedium species, but cayratinin and cyanidin glucoside were contained in the stems, young leaves and autumn leaves of all the species surveyed.