Color sensitivity

This paper reports primarily upon tests of the color sense of about thirty men who have had large experience in the color grading of vegetable oils in terms of Lovibond glasses, nearly all of these men being members of the American Oil Chemists’ Society. Similar tests on five other observers are also included for comparison. All of the oil chemists were first tested by the Stilling Chart test, but the results by this test (although reported) are not the principal matter of interest. This test was regarded merely as preliminary, serving to discover any gross abnormality of color sense. The tests of specific interest relate to the observer’s ability to report correctly very small differences in Lovibond red at 35 yellow 7.6 red on the Lovibond scale, brightness diffences being eliminated so that the judgment depends, in effect, entirely upon the observer’s sensibility to difference in dominant wave length at equal brightness. The subject’s ability in this regard was tested by the well known psycho-physical method of “right and wrong answers.” The results for each observer are expressed so as to show the probability of his perceiving correctly given small differences in Lovibond red, under certain specified conditions. The chief results may be summarized as follows:

1. 1.
   A difference of 0.1 red at 35 yellow 7.6 red is perceivedwith certainty by only very few exceptional observers. However, this difference is perceptible in the sense that its presence does affect the observer’s judgmentin the average, although he is very doubtful of the reality of such a difference.     

Friction Characteristics and Topography of Tribofilms from Anti-Wear Additives Applied to Metal V-Belt Type CVT Fluids

This study has investigated potential links between tribological performance and the morphology of tribofilms formed from anti-wear additives with application to metal V-belt pushing type continuously variable transmission fluids (B-CVTFs). The influence of metal–metal tribological properties of anti-wear additives was evaluated using a ball on plate tribometer, enabling friction and lubricant film formation to be monitored during reciprocating tests. Contact mode atomic force microscopy was utilised to investigate the nature of tribofilms at the nanometre scale. As a result, an additive formulation composed of hydrogen phosphite and over-based calcium sulphonate in a hydro-cracked mineral Group II base oil demonstrated a synergism with 8% higher friction coefficient and more stable film formation than the individual additive cases, providing a positive outcome for a B-CVTF. Tribofilm species produced by a chemical reaction between hydrogen phosphite and over-based calcium sulphonate were densely deposited on the wear scar to form a rougher surface, which may explain the higher friction observed.     

Effect of increased afterload on cardiac lipoprotein lipase and VLDL receptor expression

Fatty acids are a major source of fuel for energy production by myocytes. Lipoprotein lipase (LPL) and very low density lipoprotein (VLDL) receptor are abundantly expressed by the heart and skeletal muscles. LPL and possibly VLDL receptor represent the primary route of access to fatty acids contained in circulating triglyceride-rich lipoproteins. Physical exercise and thyroid hormone, which promote energy consumption, upregulate LPL expression in skeletal muscles. This study tested the hypothesis that increased cardiac workload might modulate myocardial LPL and/or VLDL receptor expressions. Accordingly, cardiac tissue LPL activity, LPL and VLDL receptor proteins and mRNA abundance were studied in Sprague-Dawley rats 4 weeks after induction of severe thoracic aorta constriction or sham operation. Elevation of afterload with thoracic aortic constriction led to a significant cardiomegaly and a marked upregulation of cardiac LPL activity, LPL mRNA and LPL protein abundance, but did not modify VLDL receptor mRNA or protein abundance. Thus, increased cardiac workload in this model results in upregulation of myocardial LPL expression which can enhance fatty acid availability to accommodate the heart's increased energy requirement.     

Epidemiology of clonorchiasis in Ninh Binh Province, Vietnam

We present the spatial structure of binase, a small extracellular ribonuclease, derived from 1H-NMR* data in aqueous solution. The total of 20 structures were obtained via torsion angle dynamics using DYANA program with experimental NOE and hydrogen bond distance constraints and phi and chi1 dihedral angle constraints. The final structures were energy minimised with ECEPP/2 potential in FANTOM program. Binase consists of three alpha-helices in N-terminal part (residues 6-16, 26-32 and 41-44), five-stranded antiparallel beta-sheet in C-terminal part (residues 51-55, 70-75, 86-90, 94-99 and 104-108) and two-stranded parallel beta-sheet (residues 22-24 and 49-51). Three loops (residues 36-39, 56-67 and 76-83), which play significant role in biological functioning of binase, are flexible in solution. The differences between binase and barnase spatial structures in solution explain the differences in thermostability of binase, barnase and their hybrids.     

Pattern classification using projection pursuit

This article discusses the adaptation of recently developed regression techniques to classifier design. Apart from finite sample effects, projection pursuit (PP) regression may be used to model a desired response (class) as a sum of ridge functions according to a minimum expected squared error criterion. This approach can be shown to furnish an optimal discriminant function which can satisfy the Neyman-Pearson criterion over all possible thresholds. Basis function expansions are used instead of smoothed histograms to reduce computation. Since good approximation of a discriminant by a linear combination of moderate number of ridge functions may not be easy, we introduce an improved method utilizing a nonlinear weighting function.     

Inequivalence of the two tyrosine ligands in the N-lobe of human serum transferrin

Human serum transferrin N-lobe (hTF/2N) has four iron-binding ligands, including one histidine, one aspartate, and two tyrosines. The present report elucidates the inequivalence of the two tyrosine ligands (Tyr 95 and Tyr 188) on the metal-binding properties of hTF/2N by means of site-directed mutagenesis, metal release kinetics, and absorption and electron paramagnetic resonance (EPR) spectroscopies. When the liganding tyrosines were mutated individually to phenylalanine, the resulting mutant Y95F showed a weak binding affinity for iron and no affinity for copper, whereas, mutant Y188F completely lost the ability to bind iron but formed a stable complex with copper. Since other studies have demonstrated that mutations of the other two ligands, histidine and aspartate, did not completely abolish iron binding, the present findings suggest that the tyrosine ligand at position 188 is essential for binding of iron to occur. Replacement of Tyr 188 with phenylalanine created a favorable chemical environment for copper coordination but a fatal situation for iron binding. The positions of the two liganding tyrosines in the metal-binding cleft suggest a reason for the inequivalence.     

Novel phosphoserine phosphatase inhibitors

Phosphoserine phosphatase (EC 3.1.1.3) catalyzes the final step in the major pathway of L-serine biosynthesis in brain. This enzyme may also regulate the levels of glycine and D-serine, the known and putative co-agonists for the glycine site of the N-methyl-D-aspartate receptor in caudal and rostral brain regions, respectively. Using L-phosphoserine as substrate, the rank order potency for inhibition of phosphoserine phosphatase was p-chloromercuriphenylsulfonic acid (CMPSA) > glycerophosphorylcholine > hexadecylphosphocholine > or = phosphorylcholine > N-ethylmaleimide > or = L-serine > fluoride > D-2-amino-3-phosphonopropionic acid (D-AP3). Glycerylphosphorylcholine (IC50 18 microM) was found to be an uncompetitive inhibitor of phosphoserine phosphatase. Glycerylphosphorylcholine probably binds a novel site on the enzyme since the known allosteric inhibitor L-serine is highly selective for its feedback regulatory site, indicated by the inactivity of 25 L-serine analogs. Fluoride ion (IC50 770 microM) may bind the active site as has been shown for other Mg2+-dependent enzymes. The sulfhydryl reagent CMPSA is a potent, noncompetitive inhibitor of the enzyme using L-phosphoserine as substrate (IC50 9 microM) but is > 300-fold less potent using D-phosphoserine as substrate. Substrate-dependent differences are also observed with the sulfhydryl alkylator N-ethylmaleimide, which inhibits L-phosphoserine, but stimulates D-phosphoserine hydrolysis. These sulfhydryl reagents may dissociate multimeric forms of the enzyme to form monomers; the multimeric forms and monomers may preferentially cleave L- and D-phosphoserine, respectively. Phosphorylcholine esters and sulfhydryl reagents may prove useful in determining the contribution of phosphoserine phosphatase to the biosynthesis of glycine and D-serine in neuronal tissue in vitro.