How many object colors can we distinguish? A comment on prof. Kuehni

This is a comment on Prof. Rolf G. Kuehni's article, How Many Object Colors Can We Distinguish? We give a reasoning why the previously calculated estimates for the number of discernible colors are valid, apart from the possible deviations caused by uncertainty of JND and non‐uniformity of color space, without correcting them with a coefficient proposed by Kuehni. © 2016 Wiley Periodicals, Inc. Col Res Appl, 2016     

How many colors can we distinguish? Response to comments by M. Flinkman and H. Laamanen

In his response to the comments on his article ‘How many colors can we distinguish?’ by Flinkman and Laamanen, Kuehni points out that their suggestion for just noticeable differences to be defined as diameters rather than radii in related unit difference ellipsoids or spheres lacks the conceptual and geometric logic behind JND solids and is not valid. © 2016 Wiley Periodicals, Inc. Col Res Appl, 2016     

What can we learn from a dress with ambiguous colors?

We performed objective spectroradiometric measurements on an LCD image of the recently famous Tumblr dress which is typically perceived by people as blue/black or white/gold. The average ± standard deviation of the CIELAB coordinates was as follows: For a set of 33 points in the areas considered as blue/white, L* = 46 ± 6, C*_ab = 33 ± 6, and h_ab = 282 ± 3°, and for a set of 36 points in the areas considered as black/gold, L* = 29 ± 6; C*_ab = 10 ± 4; h_ab = 16 ± 34°. Initially, this first set of values has low variability and corresponds to a blue color, whereas the second set of values has a very large hue‐angle range, including points which can be considered as both gold and black colors. We also performed spectrophotometric measurements on an original model of this dress, and, assuming D65 illuminant and CIE 1931 colorimetric standard observer, the average results were L* = 26, C*_ab = 39, and h_ab = 289°, and L* = 10, C*_ab = 1, and h_ab = 290° for the blue/white and black/gold points, respectively. We discuss the influence of different factors on the blue/black and white/gold perceptions of different people, including observers' variability in color‐matching functions, Bezold–Brücke and Abney effects, background influence, and illumination assumptions. Although more research on the effect shown in this dress is needed, we think that from this example we can learn that objects do not have specific colors; that is, color is a human perception, and many times the answer of the human visual system is not simple and relies on assumptions of unknown, and variable, origin. © 2015 The Authors Color Research & Application Published by Wiley Periodicals, Inc., 40, 525–529, 2015     

Are we able to distinguish color attributes?

The perception and understanding of the three color attributes have been analyzed from two experiments using pairs of Munsell samples, where only one of the three color attributes were changed/unchanged (Experiment I/II) at a time. In each experiment, 36 pairs with color differences of 3 different sizes (average values of 15.8 and 21.7 CIELAB units for Experiments I and II, respectively) were assessed under standardized conditions by 40 normal observers, 20 of them with previous knowledge and experience in colorimetry. At a 95% confidence level, the results from the two experiments were not significantly different, indicating that color attributes were not easily distinguished: for example, for experienced observers, the percentage of correct answers for identifying the color attribute responsible for a color difference was only 72.4%, the random probability being 33.3%. There were no significant differences between the results found by men and women. The worst distinguished attribute was Chroma, that is, the least frequent confusion was between Hue and Value or vice versa. Value differences were more easily detected for achromatic than for chromatic pairs, both for experienced and inexperienced observers. With respect to the size of the color differences, we observed that large hue differences were more easily identifiable than smaller ones, and a constant Hue was more identifiable when the entire color difference was small. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 356–367, 2000     

How can we genetically engineer oilseed crops to produce high levels of medium‐chain fatty acids?

The end products of fatty acid synthase activities are usually 16‐ and 18‐carbon fatty acids. There are however, several plant species that store 8‐ to 14‐carbon (medium‐chain) fatty acids in their oil seeds. Among the medium‐chain fatty acids (MCFA), caprylic (8:0) and capric (10:0) are minor components of coconut oil, which are used in many industrial, nutritional and pharmaceutical products. Engineering crop plants such as Brassica could provide an economical source of these oils. During the last decade many laboratories have identified, cloned and characterized both the biosynthetic and catabolic enzymes regulating the composition and levels of these unusual fatty acids in seed oil. Among the biosynthetic enzymes thioesterases (TE), β‐ketoacyl‐ACP synthases (KAS) and acyltransferases are best characterized. In fact several independent investigators have shown that combined expression of the medium‐chain specific enzymes, specifically, TE, KAS and lysophosphatidic acid acyltransferase (LPAAT) results in the production of significant levels of MCFA in seed that otherwise do not accumulate any medium‐chain fatty acid. However, any additional increase in the levels of MCFA in transgenic seeds will require further detailed studies, such as possible induction of the medium‐chain specific enzymes in β‐oxidation and the glyoxylate pathways. To examine such a possibility, a number of genes involved in the β‐oxidation cycle among them a novel enzyme now designated as ACX3, a medium‐chain specific acyl‐CoA‐oxidase, has also been cloned. This article is an attempt to summarize our current knowledge and the present status of engineering oilseed crops for production of medium‐chain fatty acids.     

How good are the Electrodes we use in PEFC?

Basically, companies and laboratories implement production methods for their electrodes on the basis of experience, technical capabilities and commercial preferences. But how does one know whether they have ended up with the best possible electrode for the components used? What should be the (i) optimal thickness of the catalyst layer? (ii) relative amounts of electronically conducting component (catalyst, with support – if used), electrolyte and pores? (iii) “particle size distributions” in these mesophases? We may be pleased with our MEAs, but could we make them better? The details of excellently working MEA structures are typically not a subject of open discussion, also hardly anyone in the fuel cell business would like to admit that their electrodes could have been made much better. Therefore, we only rarely find (far from systematic) experimental reports on this most important issue. The message of this paper is to illustrate how strongly the MEA morphology could affect the performance and to pave the way for the development of the theory. Full analysis should address the performance at different current densities, which is possible and is partially shown in this paper, but vital trends can be demonstrated on the linear polarization resistance, the signature of electrode performance. The latter is expressed through the minimum number of key parameters characterizing the processes taking place in the MEA. Model expressions of the percolation theory can then be used to approximate the dependence on these parameters. The effects revealed are dramatic. Of course, the corresponding curves will not be reproduced literally in experiments, since these illustrations use crude expressions inspired by the theory of percolation on a regular lattice, whereas the actual mesoscopic architecture of MEA is much more complicated. However, they give us a flavour of reserves that might be released by smart MEA design.     

Do we need to know and can we determine the complete macrostructures of synthetic polymers?

The complete molecular architectures of synthetic polymers, which may be called their macrostructures, consist of the types and amounts of short-range microstructural elements they contain, such as comonomer, regio- and stereosequences, branches, cross-links etc., as well as their locations along the polymer backbone. While spectroscopic probes that are only sensitive to local polymer structures, like NMR, can identify and quantify short-range microstructural elements, they are unable to locate their positions along the polymer backbone. Consequently, the present situation regarding our ability to characterize the complete chemical structures of synthetic polymers would be analogous to that of proteins if it were only possible to determine their amino acid compositions or possibly the amounts of consecutive pairs or even triplets of constituent amino acids, rather than their complete macrostructures, i.e., their complete amino acid sequences or primary structures. While the genetic DNA code may be read to determine the primary structures of most proteins, we have no such synthetic template for man-made polymers which can be utilized to determine their complete macrostructural architectures. Just as the primary sequences of proteins determine their secondary, tertiary, and even quaternary structures, and of course their resultant biological functions, it can logically be presumed that the behaviors of synthetic polymers are also principally the result of their complete structural architectures. Though important, the types and quantities of short-range microstructures polymers contain and which constitutes our present level of structural knowledge, is insufficient for the development of truly relevant structure-property relations. In addition, the degree of macrostructural heterogeneity among the chains in polymer samples is also expected to strongly influence the behaviors of materials made from them, and so this related issue also needs to be addressed. Here we summarize our recent attempts to develop and demonstrate an experimental approach that can be used to begin to characterize the complete macrostructures of synthetic polymers and to illustrate the relevance of this knowledge to understanding their properties and behaviors.     

How small nanodiamonds can be? MD study of the stability against graphitization

How small nanodiamonds can be is a crucial question for biomedical applications. To answer this question, we present here molecular dynamic simulations of the annealing of very small diamond clusters (diameter between 0.3 and 1.3 nm) of various shape in vacuum and in the presence of oxygen. Isothermal cycles of 30 ps were carried out at 500, 1000, 1500, and 2000 K with 10 ps ramps between them. Predominantly {100} faceted diamond clusters as small as 1 nm (~ 250 atoms) survive these short anneals up to 1500 K. Longer anneals at 1500 K, as well “accelerated” MD at very high temperatures, indicate that the diamond core is still preserved when thermal equilibration is reached. The primary effect of oxygen seems to be the saturation of threefold-coordinated surface carbon atoms and the etching of lower coordinated ones. Oxygen accelerates the graphitization somewhat but does not affect the critical size. Our result means that nanodiamonds with a core of only 0.8 nm can be kinetically stable up to 1500 K. This is significantly less than the lower limit of the thermodynamic stability (~ 1.9 nm).     

Shall we dance? How a multicopper oxidase chooses its electron transfer partner

Multicopper oxidases (MCOs) are encoded in the genomes of Eukarya, Bacteria, and Archea. These proteins are unique in that they contain at least four Cu atom prosthetic groups organized into one each of the three spectral classifications of copper sites in biology: type 1 (T1), type 2 (T2), and binuclear type 3 (T3), where the T2 and T3 sites form a trinuclear Cu cluster. With these four redox-active copper sites, the multicopper oxidases catalyze the four-electron (4e(-)) reduction of dioxygen to 2H2O, an activity that they alone share with the terminal heme-containing oxidases. Most MCOs exhibit broad specificity towards organic reductants, while a relatively small number of family members exhibit equally robust activity towards metal ions like Fe(II), Cu(I), and Mn(II) and, thus, are considered metallo-oxidases. This Account analyzes the structure-activity features of multicopper oxidases that determine their relative substrate specificity. Since the substrate oxidation step involves an outer-sphere electron transfer from the reductant to the T1Cu site in the protein, the concepts of Marcus theory are applied to unravel the origin of the substrate specificity of the multicopper ferroxidases.     

Is CIELAB one space or many?

Models in colour engineering can have implicit customary usage, outside of whose parameters one is not supposed to venture. CIELAB is one such model: although able to accommodate a prediction of asymmetric matches, CIELAB is used in practice to compare colours only for a given illuminant/observer condition. Should we therefore deem CIELAB to be an infinity of spaces, one for each illuminant/observer combination? This question has its roots in an oddity of CIELAB’s chromatic‐adaptation model. A chromatic‐adaptation oddity also entered CIE models that emerged after CIELAB, and leads to a similarly perplexing question.     

Colour research with architectural relevance: How can different approaches gain from each other?

Colour research from different scientific traditions start from different basic questions and use different methods and concepts. This makes it difficult to communicate and to judge result relevance in a wider perspective. Here we start from architects' need of colour knowledge and discuss recent studies of colour appearance and colour emotion, with and without explicit connection to architecture. We stress the need for further development and clarification of concepts and conclude that the multitude of studies with different approaches can be seen as cases, jointly adding to a widened and deepened understanding of colour. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2010     

How well can aerosol instruments measure particulate mass and solid particle number in engine exhaust?

Aerosol instruments provide more informative engine exhaust particulate matter (PM) data than the gravimetric filter and solid particle number methods prescribed by regulations. Yet their lack of conformity to the regulatory methods can limit their acceptance for vehicle development. This article examines the ability of the Dekati Mass Monitor (DMM), Engine Exhaust Particle Sizer (EEPS), and Micro Soot Sensor (MSS) to measure PM_2.5 mass and solid particle number relative to current motor vehicle PM emissions standards. Simultaneous PM measurements are made by these three instruments and the two regulatory methods for 50 tests of six gasoline direct injection and two port fuel injection vehicles over the U.S. Federal Test Procedure. DMM and EEPS determinations of PM mass correlate well to gravimetric values (regression slopes of 1.06 ± 0.04 and 0.98 ± 0.08) down to a few mg/mile, below which filter weighing variability becomes problematic. The MSS exhibits a lower slope of 0.79 ± 0.03 consistent with it measuring the soot fraction, rather than total PM. At emissions rates above ～10¹³ particles/mile, solid particle number determined from DMM and EEPS data correlates respectably with, but overestimates the regulatory method (regression slopes are 1.7 ± 0.1 and 1.4 ± 0.15, respectively). Below this emissions rate, the correlation degrades. EEPS estimates of PM mass are significantly improved with the recent soot optimized inversion algorithm (slope improves from 0.45 to 0.98). While they cannot replace filters and solid particle counting, the present study suggests that these instruments can be used as more informative surrogates during motor vehicle development.

© 2016 Ford Motor Company     

How much of the target for biofuels can be met by biodiesel generated from residues in Ireland?

This study focuses on biodiesel production from residues in particular tallow and used cooking oil (UCO). Ireland has 8% of the EU cattle herd with less than 1% of the EU population. Thus a significant quantity of slaughter residues is available for energy production. The total energy potential associated with slaughter wastes and UCO is estimated to be 7.07 PJ/a; 61% of which is suitable for biodiesel production. The potential quantity of biodiesel is equivalent to 2.1% of predicted transport fuel use in 2010; three quarters of the 2010 biofuels target. Biodiesel production from these two residue streams may be expressed as equivalent to 22% of arable land in Ireland under oilseed rape.     

Plasma for cancer treatment: How can RONS penetrate through the cell membrane? Answers from computer modeling

Plasma is gaining increasing interest for cancer treatment, but the underlying mechanisms are not yet fully understood. Using computer simulations at the molecular level, we try to gain better insight in how plasma-generated reactive oxygen and nitrogen species (RONS) can penetrate through the cell membrane. Specifically, we compare the permeability of various (hydrophilic and hydrophobic) RONS across both oxidized and nonoxidized cell membranes. We also study pore formation, and how it is hampered by higher concentrations of cholesterol in the cell membrane, and we illustrate the much higher permeability of H2O2 through aquaporin channels. Both mechanisms may explain the selective cytotoxic effect of plasma towards cancer cells. Finally, we also discuss the synergistic effect of plasma-induced oxidation and electric fields towards pore formation.     

The geographical distribution of variant Creutzfeldt-Jakob disease cases in the UK: what can we learn from it?

The causative agents of variant Creutzfeldt-Jakob disease (vCJD) and of bovine spongiform encephalopathy (BSE) are currently indistinguishable. However, the route(s) by which humans became infected remain unknown. The path by which humans were infected with the BSE agent might impact on the geographical distribution of cases and we therefore sought evidence of regional variation and local clustering of vCJD cases. With the notable exception of a group of five cases in Leicestershire, the absence of local clustering of vCJD cases is compatible with most human exposure to the vCJD agent arising through routes that result in the risk of infection being similar over wide geographical areas, rather than through small-scale local events. Infection through the consumption of mechanically recovered meat (MRM) contaminated with the BSE agent was a potential route for such widespread exposure. An ecological analysis relating the regional incidence of vCJD to historical dietary data does not provide a dear evidence that humans became infected through consumption of MRM.