Properties of Mexican Tropical Palm Oil Flower and Fruit Fibers for Their Prospective Use in Eco-Friendly Construction Material

The palm oil industry is the leading source of palm oil waste fibers. The disposal of palm oil waste fibers by burning or dumping causes environmental issues such as the emission of CO2 and a diminution in soil fertility. Natural fiber reuse in construction materials such as concrete, mortar and adobe bricks as reinforcement provides a possible eco-friendly solution for fiber waste management. Palm oil flower fibers (POFL) obtained from palm oil empty fruit bunches and palm oil fruit fibers (POFR) obtained from palm oil fruit are two important types of palm oil fibers. Valorization of palm oil fibers requires a detailed analysis of their physical, chemical and mechanical characteristics. In this research, tropical palm oil flower and palm oil fruit fibers from Mexico were studied. Fiber extraction, preparation and testing were performed to observe their characteristics, which include water absorption, density, length, section estimation, chemical composition, thermal conductivity, thermal analysis (ATG) and tensile strength. The length, diameter and density of natural fibers have a significant influence on the strength and quality of composite materials. The characteristics of fibers vary with their chemical composition. Mechanical testing of palm oil fibers indicates a large variation in the tensile strength of palm oil flower and fruit fibers. Both palm oil flower and palm oil fruit fibers exhibit bilinear tensile load–deflection behavior associated with the alignment of cellulose along their fiber axis. The thermal characteristics of fibers indicate low thermal stability and thermal conductivity, which are essential for their use in building materials.

EXPRESS: Raman Investigation of the Processing: Structure Relations in Individual Poly(ethylene terephthalate) Electrospun Fibers

Electrospun fibers often exhibit enhanced properties at reduced diameters, a characteristic now widely attributed to a high molecular orientation of the polymer chains along the fiber axis. A parameter that can affect the molecular organization is the type of collector onto which fibers are electrospun. In this work, we use polarized confocal Raman spectromicroscopy to determine the incidence of the three most common types of collectors on the molecular orientation and structure in individual fibers of a broad range of diameters. Poly(ethylene terephthalate) is used as a model system for fibers of weakly crystalline polymers. A clear correlation emerges between the choice of collector, the induced molecular orientation, the fraction of trans conformers, and the degree of crystallinity within fibers. Quantitative structural information gathered by Raman contributes to a general description of the mechanism of action of the collectors based on the additional strain they exert on the forming fibers.

Experimental Study and Analysis of Light Scattering Patterns of Bragg Fibers Fabricated in PECVD

Light scattering patterns are commonly used in industry to assess fiber quality. In this work, scattering patterns of Bragg fibers are studied. Optical fibers are coated with alternating layers of Silicon Nitride and Silica using Plasma Enhanced Chemical Vapor Deposition. A laser beam incident perpendicular to the fiber axis scatters off creating patterns distinct from that of uncoated fibers which exhibit continuous front lobe. Effect of variation in layer properties, polarization, wavelength and fiber symmetry is observed in the patterns. Anomalous suppression and enhancement in angular scattering pattern is explained through a scattering angle diagram. Features in the pattern are mapped to reflectance of the Bragg stack and it is found that a stopband creates the anomalous features in the scattering.

Fabrication and Characterization of Line-by-Line Inscribed Tilted Fiber Bragg Gratings Using Femtosecond Laser

In this paper, we studied the basic characteristics of tilted fiber Bragg gratings (TFBGs), inscribed line-by-line. Experimental results showed that if the TFBGs were located within different planes parallel to the fiber axis, the spectra performed differently. For 2°TFBG, if it was located near the central plane, the Bragg resonance was stronger than ghost mode resonance, and the order reversed if it was located near the boundary between core and cladding. As the tilted angle increased, the range of cladding mode resonance increased. When the tilted angle was larger than 12°, the birefringence effect was observed. Based on the birefringence phenomenon, torsion characteristics were experimentally studied; the sensitivity was about 0.025 dB/degree in the linear variation range. The harmonic order of TFBGs also affected the transmission spectrum. Leaky mode resonance was observed in the 8th order TFBG, and torsion (or polarization) influenced the spectrum of the 8th order TFBG. Our research represented the theory of line-by-line inscribed TFBGs and provided an inscription guidance for TFBGs.

Self-Aligned Emission of Distributed Feedback Lasers on Optical Fiber Sidewall

This article assembles a distributed feedback (DFB) cavity on the sidewalls of the optical fiber by using very simple fabrication techniques including two-beam interference lithography and dip-coating. The DFB laser structure comprises graduated gratings on the optical fiber sidewalls which are covered with a layer of colloidal quantum dots. Directional DFB lasing is observed from the fiber facet due to the coupling effect between the grating and the optical fiber. The directional lasing from the optical fiber facet exhibits a small solid divergence angle as compared to the conventional laser. It can be attributed to the two-dimensional light confinement in the fiber waveguide. An analytical approach based on the Bragg condition and the coupled-wave theory was developed to explain the characteristics of the laser device. The intensity of the output coupled laser is tuned by the coupling coefficient, which is determined by the angle between the grating vector and the fiber axis. These results afford opportunities to integrate different DFB lasers on the same optical fiber sidewall, achieving multi-wavelength self-aligned DFB lasers for a directional emission. The proposed technique may provide an alternative to integrating DFB lasers for applications in networking, optical sensing, and power delivery.

Tumbling and anomalous alignment of optically levitated anisotropic microparticles in chiral hollow-core photonic crystal fiber

The complex tumbling motion of spinning nonspherical objects is a topic of enduring interest, both in popular culture and in advanced scientific research. Here, we report all-optical control of the spin, precession, and nutation of vaterite microparticles levitated by counterpropagating circularly polarized laser beams guided in chiral hollow-core fiber. The circularly polarized light causes the anisotropic particles to spin about the fiber axis, while, regulated by minimization of free energy, dipole forces tend to align the extraordinary optical axis of positive uniaxial particles into the plane of rotating electric field. The end result is that, accompanied by oscillatory nutation, the optical axis reaches a stable tilt angle with respect to the plane of the electric field. The results reveal new possibilities for manipulating optical alignment through rotational degrees of freedom, with applications in the control of micromotors and microgyroscopes, laser alignment of polyatomic molecules, and study of rotational cell mechanics.

Molecular and Crystal Structure of a Chitosan−Zinc Chloride Complex

We determined the molecular and packing structure of a chitosan–ZnCl2 complex by X-ray diffraction and linked-atom least-squares. Eight D-glucosamine residues—composed of four chitosan chains with two-fold helical symmetry, and four ZnCl2 molecules—were packed in a rectangular unit cell with dimensions a = 1.1677 nm, b = 1.7991 nm, and c = 1.0307 nm (where c is the fiber axis). We performed exhaustive structure searches by examining all of the possible chain packing modes. We also comprehensively searched the positions and spatial orientations of the ZnCl2 molecules. Chitosan chains of antiparallel polarity formed zigzag-shaped chain sheets, where N2···O6, N2···N2, and O6···O6 intermolecular hydrogen bonds connected the neighboring chains. We further refined the packing positions of the ZnCl2 molecules by theoretical calculations of the crystal models, which suggested a possible coordination scheme of Zn(II) with an O6 atom.

Article Review on Vectran-Super Fiber from Thermotropic Crystals of Rigid-Rod Polymer

According to the economic and environmental perspective, multifilament Vectran, yarn spun from liquid crystal polymer, is important because of its quite simple processing during spinning in a wide range of injection moulding, extrusion moulding, and melt spinning. Vectran fiber is an aromatic polyester spun from a liquid crystal polymer in a melt extrusion process. This process orients the molecules along the fiber axis, resulting in a high tenacity fiber, and Vectran melts at 330°C. Heat treatment can improve and vary the tensile strength of Vectran fiber. On average, tensile strength for Vectran is 26 grams/denier (grouped as a high tenacity grade) and the strength of the fiber is maintained after several flexing and bending actions. Abrasion resistance of Vectran is even higher than a similarly sized aramid yarn. In addition, the original dimensions are maintained under variance of temperature with negligible creep and shrinkage. Vectran fiber, characterized by its golden color, high strength and modulus, thermal stability at high temperatures, low creep, and good chemical stability, can be used in many various industries starting from ropes and cables to profound sea survey and military products.

Сhemical processing of corn head wrappers on fiber semi-finished products

Non-woody plant raw materials are of scientific interest in the effective processes of their chemical processing into fibrous semi-finished products and the properties of the finished product. A feature is the study of local species of annual plants that are among the most cultivated. Therefore, scientists are increasingly experimenting with corn waste for the possibility of their use in the manufacture of paper or cardboard, the study of their properties, but the results are not always stable. Our work focuses on the use of corn waste in the form of cob wrappers and obtaining from them fibrous semi-finished products by the soda-soda method. The restraining factor of obtaining cellulose from this raw material is the variability of chemical composition, features of morphological structure, the insufficient study of delignification depending on the cost of active alkali, the influence of impregnation on this process, its duration, and temperature. Wraps in the form of chaff were boiled with a solution at the consumption of active alkali 6 %, 10 %, and 14 % in units. Na2O by mass abs. dry. raw materials for impregnation for 15 min or without impregnation and subsequent cooking at a final temperature in the range of 100 0C - 160 0C for 15 or 30 min. The semi-finished products obtained as a result of cooking were ground, samples were made and their strength indicators were determined. It should be noted that the wrappers contain about twice less lignin, about 7.5-14 %, compared to wood – 23-28 %, which led to the choice of the minimum duration of cooking. However, the semi-finished products obtained from them are difficult to grind. This pattern is partly explained by the location of fibrils in the secondary wall of the middle layer S2 at an angle of 45-500 to the fiber axis, and the direction of fibrils in adjacent layers S1 and S3 of the cell wall is opposite, which inhibits splitting into individual fibrils. It is shown that impregnation has a positive effect on the quality of raw material digestion and physical and mechanical properties. At a temperature of 130 0C for only 15 and 30 minutes of cooking with impregnation and the consumption of active alkali 14 % in units. Na2O achieved high strength of semi-finished products. Increasing the cooking temperature to 160 0C and the maximum consumption of active alkali to 14 % per unit. Na2O leads to a sharp decrease in the yield and strength of semi-finished products. This pattern is logically explained by theoretical provisions on the processes of delignification of raw materials. At the same time, the temperature and the consumption of alkali increase the destruction of the carbohydrate part, primarily its low-molecular fractions, which are responsible for the formation of strong hydrogen bonds between the fibers. The optimal conditions for delignification at a temperature of 160 0C can be considered the consumption of active alkali 10 % per unit. Na2O with impregnation and cooking time of 15 minutes and obtaining high yield cellulose. The proposed raw materials for corn cob wrappers and technological modes of its chemical processing provide the production of fibrous semi-finished products with high strength.

Fibrilar Polymorphism of the Bacterial Extracellular Matrix Protein TasA

Functional amyloid proteins often appear as fibers in extracellular matrices of microbial soft colonies. In contrast to disease-related amyloid structures, they serve a functional goal that benefits the organism that secretes them, which is the reason for the title “functional”. Biofilms are a specific example of a microbial community in which functional amyloid fibers play a role. Functional amyloid proteins contribute to the mechanical stability of biofilms and mediate the adhesion of the cells to themselves as well as to surfaces. Recently, it has been shown that functional amyloid proteins also play a regulatory role in biofilm development. TasA is the major proteinaceous fibrilar component of the extracellular matrix of biofilms made of the soil bacterium and Gram-positive Bacillus subtilis. We have previously shown, as later corroborated by others, that in acidic solutions, TasA forms compact aggregates that are composed of tangled fibers. Here, we show that in a neutral pH and above a certain TasA concentration, the fibers of TasA are elongated and straight and that they bundle up in highly concentrated salt solutions. TasA fibers resemble the canonic amyloid morphology; however, these fibers also bear an interesting nm-scale periodicity along the fiber axis. At the molecular level, TasA fibers contain a twisted β-sheet structure, as indicated by circular dichroism measurements. Our study shows that the morphology of TasA fibers depends on the environmental conditions. Different fibrilar morphologies may be related with different functional roles in biofilms, ranging from granting biofilms with a mechanical support to acting as antibiotic agents.