Recycled fiber from straw waste: effect of take-up speed and spinneret diameter to linear density and tenacity

Recycled fiber has a great potential as a solution to meet overgrowing synthetic fiber demand and reduce plastic waste in the same time. In the previous research, bottle cap waste is used as the material of the recycled fiber. The result shows that fiber tenacity of recyled fiber from bottle cap waste has low tenacity, different polymer. This phenomena may have been caused by the present of pigment molecule. This research focused on producing recycled fiber from straw waste which has low pigment content. Straw waste was washed and cleaned before the cutting process. Then, the waste was processed in the experiment melt spinning machine with plunger system and single hole orifice in various diameter, 4 mm, 10 mm and 15 mm. The processing temperature was 140° C temperature in three take-up speed, 3.00 m/minutes, 10.30 m/ minutes and 19.16 m/ minutes. The diameter and cross section shape of recycled polyethylene fiber were obtained by using electric microscope with software assistance. The linear density of the recycled fiber was analysed by calculating it with denier and the mechanical strength of the fiber was measured in accordance with the ASTM D 3379-75 standard. High take-up speed leads to higher linear density and take-up speed value is proportionally linear with the tenacity of fiber produced. Moreover, the spinneret diameter is proportionally linear with linear density but it is inversely linear with the tenacity of the fiber produced.

Fluorescence as a means of colour signal enhancement

Fluorescence is a physico-chemical energy exchange where shorter-wavelength photons are absorbed by a molecule and are re-emitted as longer-wavelength photons. It has been suggested a means of communication in several taxa including flowers, pitcher plants, corals, algae, worms, squid, spiders, stomatopods, fish, reptiles, parrots and humans. The surface or object that the pigment molecule is part of appears to glow due to its setting rather than an actual production of light, and this may enhance both signals and, in some cases, camouflage. This review examines some known uses of fluorescence, mainly in the context of visual communication in animals, the challenge being to distinguish when fluorescence is a functional feature of biological coloration or when it is a by-product of a pigment or other molecule. In general, we conclude that most observations of fluorescence lack enough evidence to suggest they are used in visually driven behaviours. This article is part of the themed issue ‘Animal coloration: production, perception, function and application’.

Variation in carotenoid–protein interaction in bird feathers produces novel plumage coloration

Light absorption by carotenoids is known to vary substantially with the shape or conformation of the pigment molecule induced by the molecular environment, but the role of interactions between carotenoid pigments and the proteins to which they are bound, and the resulting impact on organismal coloration, remain unclear. Here, we present a spectroscopic investigation of feathers from the brilliant red scarlet ibis ( Eudocimus ruber, Threskiornithidae), the orange-red summer tanager ( Piranga rubra, Cardinalidae) and the violet-purple feathers of the white-browed purpletuft ( Iodopleura isabellae, Tityridae). Despite their striking differences in colour, all three of these feathers contain canthaxanthin (β,β-carotene-4,4′-dione) as their primary pigment. Reflectance and resonance Raman (rR) spectroscopy were used to investigate the induced molecular structural changes and carotenoid–protein interactions responsible for the different coloration in these plumage samples. The results demonstrate a significant variation between species in the peak frequency of the strong ethylenic vibration ( ν 1 ) peak in the rR spectra, the most significant of which is found in I. isabellae feathers and is correlated with a red-shift in canthaxanthin absorption that results in violet reflectance. Neither polarizability of the protein environment nor planarization of the molecule upon binding can entirely account for the full extent of the colour shift. Therefore, we suggest that head-to-tail molecular alignment (i.e. J-aggregation) of the protein-bound carotenoid molecules is an additional factor.

The Enzymatic Action of Cellulase on Pigment-Dyed Cotton Fabrics

In this research, cotton fabrics were colored with a pigment suspension, and then treated with an acid cellulase to investigate the influences of pre-existing pigment on cellulase action. It was found that the pigment on cotton surface could increase the affinity between cotton and cellulase protein due to the mutual attraction between pigment molecule and non-polar residues in the enzyme. However, it was observed that the existing pigment would suppress enzymatic activity by testing the soluble reducing sugars liberated during the treatment. The main reason is that the pigment could reduce the accessibility of cellulase protein to the cotton molecular chains by steric hindrance.

Crystal structure of a polychloroquinone soil pigment

The crystal structure of the title compound, C20H4Cl6O5,C6H6, has been determined by single-crystal X-ray diffraction at 298 K. Crystals are monoclinic, C2/c, a 7.258(4), b 19.530(7), c 17.027(11) Ǻ, β 93.59(3)°, Z 4. Both pigment and solvent molecules are located about crystallographic 2 axes; the pigment molecule is considerably distorted as a result of interaction between substituent chlorine atoms on adjacent rings.

Primary photochemical reactions in chloroplast photosynthesis

Photosynthesis begins with the absorption of light energy and this absorbed energy is transferred to special sites, termed reaction centres. At these sites, the light energy is transformed into chemical products through an oxidation-reduction reaction that generates the primary reactants, an oxidized pigment molecule (P+) and a reduced electron acceptor (A–) (Clayton, 1972). The subsequent reactions of these species in the dark ultimately results in the formation of chemical products required for the fixation of CO2. In this essay we will discuss the nature of the primary reactants generated in the light reactions of chloroplast photosynthesis, stressing recent advances in the identification and characterization of such reactants.

Light-Evoked and Spontaneous Discrete Waves in the Ventral Nerve Photoreceptor of Limulus

Discrete waves, recorded from the ventral nerve photoreceptor, occur in the light and in the dark. Spontaneous waves, on the average, are smaller than light-evoked waves. This suggests that not all spontaneous waves can arise from spontaneous changes in the visual pigment molecule identical to changes induced by photon absorption. Spontaneous and light-evoked waves are statistically independent of each other. This is shown by determination of frequency of response as a function of pulse energy for short pulses and determination of the distribution of intervals between waves evoked by steady lights. The available data can be explained by two models. In the first each photon produces a time-dependent excitation that goes to zero the instant the wave occurs so that the number of effective absorptions from a short light pulse equals the number of waves produced by the light pulse. In the second the excitation produced by photon absorption is unaffected by the occurrence of the waves so that the number of waves produced from a short light pulse may be different from the number of effective absorptions. Present results do not allow a choice between the two models.

Microspectrophotometry of visual pigments

Visual pigments are embedded in the disc membranes of the outer segments of vertebrate rods and cones and in the microvilli of invertebrate visual cells. The pigment molecule in both is a most fascinating aggregate of known (the ubiquitous II-cis isomer of vitamin A1 or A2-aldehyde = retinal1 or 2; Hubbard & Wald, 1952) covalently bonded to the unknown (a protein termed opsin) (Anderson, Hoffman & Hall, 1971). This conjugated molecule is called rhodopsin or dehydrorhodopsin (porphryopsin) when the prosthetic portion is retinall or 2 respectively. So sensitive is this sterically hindered, bent and twisted molecule to light that absorption of one photon can initiate its isomerization to the all trans form. This conformational change is but one (but the best known) of the factors leading to receptor membrane changes ushering in the visual impulse.