A new colour‐perception lantern

Holmes, J G; Wright, W. D.

doi:10.1002/col.5080070204

Cited by 23 publications

(25 citation statements)

References 5 publications

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“…It was developed to replace the Board of Trade lantern after an inquiry on vision standards iqmaritime occupations.177 There are two versions (A and B) 178 Path Indicator (PAPI) used in airports. Tanabe and associatersls6 used red, yellow and yellow-green LEDs.…”

Section: Holmeswright Lantern (H-w)mentioning

confidence: 99%

Clinical colour vision tests

Dain

2004

Clinical and Experimental Optometry

153

126

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The structure and function of the available and significant clinical colour vision tests are reviewed in the light of the needs in the clinical examination of congenital and acquired colour vision deficiencies. The tests are grouped and described as pseudoisochromatic plates, arrangement tests, matching tests and vocational tests. The colorimetric constructions of the test types are described and the efficiency of their performance and usefulness discussed. Recommendations are made for basic and extended test batteries, when examining of congenital and acquired colour vision deficiencies in the consulting room.

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Section: Holmeswright Lantern (H-w)mentioning

confidence: 99%

Clinical colour vision tests

Dain

2004

Clinical and Experimental Optometry

153

126

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“…6 A, as derived independently by three groups [27] from fibre X-ray scattering measurements (see Fig. 5 , a ) .…”

Section: Bmer 3a L6mer 4d 16mer 4a (Fully Deprotected)mentioning

confidence: 99%

“…They are used by microorganisms as a means to store energy and reductase equivalents and as a carbon source (high-molecular-weight s-P(3-HB), > lo5 Dalton). A copolymer of P(3-HB) and P(3-HV) (V = valerate) is produced by fermentation and sold as a biodegradable and biocompatible plastic material under the trade name BZOPOL [6]. Low-molecular-weight P(3-HB) (100-200 units) was found in the membranes of prokaryotic and eukaryotic cells.…”

mentioning

confidence: 99%

Synthesis of Linear Oligomers of (R)‐3‐Hydroxybutyrate and Solid‐State Structural Investigations by electron microscopy and X‐ray scattering

Seebàch

Bürger

Müller

et al. 1994

Helvetica Chimica Acta

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Repetitive treatment of the biopolymer P(3-HB) (molecular weight > lo5 Dalton, storuge OJ s-P(3-HB)), with lithium hexamethyl disilazanid (LHMDS) at -70" in THF leads to a mixture of oligomers with increasingly sharp distribution around a 15-, 30-, and 45mer. Discrete fragments are also isolated when P(3-HB) is heated under reflux (89O) in neat Et,N. Linear oligo(3-HB) derivatives (3-7) containing up to 96 3-HB units are synthesized using an exponential segment-coupling strategy. These oligomers are used to calibrate size-exclusion chromatography columns for the analysis of oligo(3-HB) samples from the different sources. The linear oligo-(3-HB) derivatives also served as a model with respect to the physical properties ofhigh molecular weight P(3-HB) and were investigated as such by transmission electron microscopy (TEM) and by small-and wide-angle X-ray scattering (SAXS and WAXS). The thicknesses of the lamellar crystallites (long periods) formed by the Rmer, 16mer, and 32mer, are ca.26, 52, and 53 A, respectively, indicating that the 32mer molecules are folded once, very tightly, into a 'hair-pin'-type conformation. High-molecular-weight P(3-HB). which was crystallized in a similar way, also has a lamellar crystallite thickness of ca. [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65] A. Thus, the treatment of P(3-HB) with LHMDS at low temperature causes etching of the amorphous regions, an effect well known in polymer science for studying the regularity of chain folding. The ca. 50-A packing within the tight folds of P(3-HB) is discussed in view of its possible function in ion transport through cell membranes.Polyhydroxybutyrate (P(3-HB)) is the prototype of a class of biopolymers [I] [2] called polyhydroxyalkanoates (PHA; for review articles, see . They are used by microorganisms as a means to store energy and reductase equivalents and as a carbon source (high-molecular-weight s-P(3-HB), > lo5 Dalton). A copolymer of P(3-HB) and P(3-HV) (V = valerate) is produced by fermentation and sold as a biodegradable and biocompatible plastic material under the trade name BZOPOL [6]. Low-molecular-weight P(3-HB) (100-200 units) was found in the membranes of prokaryotic and eukaryotic cells. It forms complexes, for instance, with calcium polyphosphate and albumin (c-P(3-HB)) [7]. The structure and function of c-P(3-HB) are greatly in debate, concerning suggestions including stabilizing proteins to a Ca2+ polyphosphate (PPi), and acting as a DNA channel through lipid membranes [7]. We have embarked on an investigation to obtain information on the structure and properties of oligo(3-HB) derivatives [3].

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“…Ruland (15) and Vonk (16) have shown that deviations from ideal Porod-type behaviour for lamellar structures alter this behaviour such that for the sharp boundary model and for the (three-phase) diffuse interface model, where K, is proportional to the electron density difference between phases and 0 is an indication of the interface thickness in eq. [2] and of the density fluctuations within phases in eq.…”

Section: Small-angle X-ray Scatteringmentioning

confidence: 99%

“…Poly(P-hydroxybutyrate), PHB, and its random copolymers with 3-hydroxyvalerate, P(3HB-co-3HV) are bacterially produced biodegradable thermoplastics (1)(2)(3). They have found a market niche as biodegradable packaging materials and surgical implants due, in part, to properties imparted by their unique crystallization behaviour (4,5).…”

Section: Introductionmentioning

confidence: 99%

Cocrystallization in random copolymers of poly(β-hydroxybutyrate-co-β-hydroxyvalerate) and its effect on crystalline morphology

Orts¹,

VanderHart²,

Bluhm³

et al. 1995

Can. J. Chem.

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Small-angle X-ray scattering (SAXS) and solid state CPMAS I3c NMR were used to describe the crystalline morphology of a series of bacterially produced poly((3-hydroxybutyrate-co-P-hydroxyvalerate) copolymers containing random distributions of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV). Modeling of SAXS results showed that the morphology of this isodimorphic system is better described by two phases, crystalline and amorphous, having defects within each domain. This is in contrast to a model with a large interfacial region between phases. For the 3HV composition range 0-27 mol%, the polymer crystallizes in a poly(P-hydr0xybutyrate)-type crystalline lattice. Solid state NMR results showed that there is significant incorporation of the 3HV minor component into the poly(P-hydroxybutyrate) crystalline phase over this composition range. The ratio of the 3HV content in the crystalline phase relative to the overall 3HV content is not linear, but increases with increasing 3HV. For the 21 and 27% 3HV samples, the 3HV content in the crystalline phase is as much as 213 of the overall 3HV content. Inclusion of 3HV is correlated to an increase in crystalline disorder (as measured by SAXS), implying that it is easier to accommodate the bulkier 3HV comonomer into a crystalline region that already contains defects.Key words: bacterial polyesters, poly(3-hydroxyalkanates), small-angle X-ray scattering, solid state NMR, cocrystallization.RCsumC : On a utilisC la diffraction des rayons X B de petits angles (SAXS) et la RMN du 13c CPMAS B 1'Ctat solide pour dCcrire la morphologie cristalline d'une sCrie de copolymkres poly(P-hydroxybutyrate-co-phydroxyvalCrate) produits par une voie bactCrienne et contenant des distributions au hasard de 3-hydroxybutyrate (3HB) et de 3-hydroxyvalCrate (3HV). Un modelage des resultats SAXS a montrC que la meilleure f a~o n de dCcrire la morphologie de ce systkme isodimorphique est B l'aide de deux phases, l'une cristalline et l'autre amorphe, ayant des dkfauts dans chaque domaine. Pour une composition de 3HV allant de 0 i 27 mol%, le polymkre cristallise dans une rCseau cristallin du type poly(P-hydroxybutyrate). Les rCsultats de la RMN B l'etat solide ont montrC que, sur cette plage decomposition, il se produit une incorporation importante du composant mineur du 3HV dans la phase cristalline du poly(P-hydroxybutyrate). Le rapport de la quantitC de 3HV contenue dans la phase cristalline par rapport B la quantitC totale de 3HV n'est pas linCaire; il augmente avec une augmentation du 3HV. Pour les Cchantillons contenant 21 et 27% de 3HV, la quantitC de 3HV contenue dans la phase cristalline reprksente pratiquement les 213 de la quantitC totale de 3HV. I1 existe une corrClation entre l'inclusion du 3HV et l'augmentation du dCsordre cristallin (tel que mesurC par SAXS); ceci implique qu'il est plus facile d'accommoder le gros comonombre 3HV dans une region cristalline qui contient dCjB des dCfauts.

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A new colour‐perception lantern

Cited by 23 publications

References 5 publications

Clinical colour vision tests

Clinical colour vision tests

Synthesis of Linear Oligomers of (R)‐3‐Hydroxybutyrate and Solid‐State Structural Investigations by electron microscopy and X‐ray scattering

Cocrystallization in random copolymers of poly(β-hydroxybutyrate-co-β-hydroxyvalerate) and its effect on crystalline morphology

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