Incorporation Of Pigment Research Articles

Preparation and Characterization of a Polymeric Bulk Electro-Optic Modulator

The basic theoretical concepts on which the electro-optic linear effect are based and the optic modulation are briefly described in this work. A novel method for obtaining a doped bulk polymer with electro-optic properties by means of the incorporation of an organic pigment called 2-Methyl-4-Nitroaniline (MNA) in epoxy resin followed by a poling technique of the MNA molecules by means of the application of a strong electric field is proposed. Also, the construction of an optic modulator cell is described showing the experimental arrangement and the results obtained, with the corresponding calculation of their main parameters. A simplified mathematical model is also proposed.

Influence of the Interphase on Impact Properties of Zirconium Silicate Filled High-Density Polyethylene

Abstract Yellow zirconium silicate is a promising substitute for cadmium pigments used in plastics. However, the incorporation of zircon pigment in HDPE without loss of impact strength is required. By introducing the untreated pigment in the polymer, the impact strength reduces to 60% of the value for the unfilled polymer. Different types of silane coupling agents were used to regain the impact strength of the composite. Octadecylsilane acted as a wetting agent rather than as a coupling agent. The impact strength hardly improved. A vinyl functional and a methacryloxy functional silane improved the impact strength to 70% relative to the unfilled polymer. The physically bonded, interdiffused network formed by silane and polymer improves the impact strength by the flexible nature of the interphase. An azidosilane improved the impact strength only to 73%: the interphase bonded covalently to the polymer as well as to the filler, in that way improving the impact strength, but behaving as a brittle system. A rel...

The protective action of paint films

The protective action of paint films has been investigated by a zero resistance ammeter technique. Steel substrates were prepared with both pigmented and non-pigmented coatings based on a vinyl chloride-maleic ester copolymer. The test specimens were immersed in 6% NaCl solution and coupled with zinc and copper via the zero resistance ammeter, the galvanic current being continously recorded. It was found that the main protective action of the paint arose from polarisation of the cathodic reaction, with some contribution from resistance polarisation. Little difference in corrosion behaviour was found from incorporation of an active pigment instead of an inert pigment. A most important find has been an apparent memory effect with paint coatings which leads to a large current surge on reversal of the substrate polarity. This current surge, denoting enhanced ion transport across the film, is of great theoretical and practical interest.

Interactions of retinol-binding protein with various chromophores and with thyroxine-binding protein. A model for visual pigments

The properties of retinol-binding protein from human serum were compared with those of rhodopsin in an attempt to learn more about the role of protein in visual pigments. In the serum, retinol-binding protein (mol wt. 21 000) tightly binds one molecule of all- trans-retinol and one molecule of the tetrameric protein prealbumin (mol. wt. of tetramer, 54 000). Apo-retinol binding protein was found to be completely dissociated from prealbumin under conditions in which native retinol-retinol-binding protein and reconstituted all- trans-retinol-retinol-binding protein were tightly bound. This difference in binding to prealbumin between apo- and holo-retinol-binding protein is due most probably to different conformations of the apo- and holo-protein. By analogy, it is suggested that the incorporation of the retinal chromophore into apo-visual pigment might act as recognition marker for the incorporation of visual pigment into the photoreceptor disc membrane. Apo-retinol binding protein was shown to form stable 1 : 1 molar complexes with retinols, retinals, retinoic acid, retinyl acetate and retinyl oxime, but not with retinyl palmitate. Only the retinol isomer and retinoic acid-retinol-binding protein complexes were bound to prealbumin at physiological ionic strength, while the other chromophores-retinol·binding protein complexes were not. The various chromophores were all bound to the same site on the retinol-binding chromophore, the binding was noncovalent and irreversible under normal physiological conditions. All the chromophores-retinol-binding protein complexes showed a large induced optical activity of the chromophore absorption band upon binding to the protein. The rotatory strength of the circular dichroism bands of the various chromophore retinol-binding protein complexes was of the same order of magnitude as that of rhodopsin. The binding of retinol and retinal to bovine serum albumin did not produce optical activity in the chromophore absorption band.

Location and first appearance of rat incisor pigmentation.

abstract – Maxillary incisors were obtained from rats aged 10 to 70 d. The distribution of iron pigment was studied in a dissection microscope. The incorporation of pigment into the enamel started at the age of 10–12 d about 0.6 mm from theoriginal incisal end of the tooth. While initially very faint, the degree of pigmentation increased gradually, and at 28 d the characteristic orange color was present. A 12‐day specimen was sectioned longitudinally and analyzed by the electron microprobe. The iron content of the surface layer of enamel 0.6 and 0.8 mm from the incisal end was 0.3 % and 0.7 %, respectively. The original incisal tip, devoid of pigmented enamel, was removed by attrition before 21 d. Hence, the pigment extended to the incisal edge at the age when the animals became dependent upon a gnawing and masticatory function. The distance from the pigment incorporation zone to the incisal end increased with age, whereas the distance from the pigment incorporation zone to the developing end of the tooth remained relatively unchanged. Apparently, the processes of differentiation, formation and maturation of rat incisor enamel require a certain period of time or a constant passage from the growing end, regardless of the age of the animal.