Polar Components Research Articles

Broadband Linear to Circular Polarizer Based on Multilayer Frequency-Selective Surface

In this work, a transmission polarizer is described by using a frequency-selective surface to transform linearly polarized waves into circularly polarized waves. The linear to circular (LTC) polarizer consists of four layers. Two types of unit cells are designed in the LTC polarizer to improve design freedom. As a result, two orthogonal polarized components of transmission waves display nearly 90° phase differences while maintaining nearly high transparency for the generation of CPWs. The less than 3 dB axial ratio with a fractional width of over 76.8% from 9.20 to 20.67 GHz for this LTC polarizer is obtained. Even when the incident angle reaches 20°, its operating frequency band covers 9.69 to 20.21 GHz. Compared with the converters proposed before, the one proposed in this paper has a wider bandwidth. In order to evaluate the design strategy, a prototype is manufactured and tested. The results of the simulation and the experiment are in good accord.

Cylindrical vector beams demultiplexing communication based on a vectorial diffractive optical element

Abstract Cylindrical vector beams with polarization singularities, transmission stability and turbulence resilient, are orthogonally structured light beams providing new degrees of freedom for multiplexing optical communications. The demultiplexing of the CVBs with high efficiency and low crosstalk is of vital importance for the practical applications. Here, we propose a lens-less CVB sorting approach with a set of dielectric metasurface devices. The metasurface is composed of elliptical silicon nanopillars, which are capable of vector field steering. By performing mode transformations on both left-handed and right-handed polarization components of the CVBs, cylindrical vector beams can be demultiplexed with high efficiency and reduced crosstalk. Furthermore, by adjusting the phase response of the vectorial diffractive element into a set of Pancharatnam–Berry (PB) phase planes, we experimentally demonstrate 11 CVBs sorting with a set of P–B phase liquid crystal devices. The proposed device may benefit the CVB-based mode multiplexing communications in future.

Changes of lipid composition from culture fluid during the production of antibiotic salinomycin

A major step in the biotechnological process of production of antibiotic salinomycin is fermentation, which has the greatest impact on the quality of the final product. Vegetable oils (rapeseed or soybean) are used as nutrient medium during fermentation, with some of the lipids embedded in the final product. Data on their effect on product quality is missing, which is why a study of the changes in the composition of lipids in cultural fluid during the fermentation process was conducted. The composition of the residual lipids isolated from three samples of the culture fluid during fermentation (213, 405 and 490 hours), was investigated before drying the final product. The lipid content of the samples was 6.3%, 3.5% and 6.2%. The main trend is an increase in the amount of saturated fatty acids at the expense of a decrease in unsaturated acids. The amount of tocopherols during the fermentation process increased as well as γ-tocopherol, while the amount of α-tocopherol decreased. The content of carotenoids decreased twice during fermentation. Phosphatidylcholine and phosphatidylethanolamine were identified as major polar lipid components. The main phospholipid classes contain mainly palmitic, stearic and oleic acids. Significant changes in general lipid composition were observed during the biosynthesis process.

Not Just Surface Energy: The Role of Bis(pentafluorophenoxy) Silicon Phthalocyanine Axial Functionalization and Molecular Orientation on Organic Thin-Film Transistor Performance.

Understanding the effect of surface chemistry on the dielectric-semiconductor interface, thin-film morphology, and molecular alignment enables the optimization of organic thin-film transistors (OTFTs). We explored the properties of thin films of bis(pentafluorophenoxy) silicon phthalocyanine (F10-SiPc) evaporated onto silicon dioxide (SiO2) surfaces modified by self-assembled monolayers (SAMs) of varying surface energies and by weak epitaxy growth (WEG). The total surface energy (γtot), dispersive component of the total surface energy (γd), and polar component of the total surface energy (γp) were calculated using the Owens-Wendt method and related to electron field-effect mobility of devices (μe), and it was determined that minimizing γp and matching γtot yielded films with the largest relative domain sizes and highest resulting μe. Subsequent analyses were completed using atomic force microscopy (AFM) and grazing-incidence wide-angle X-ray scattering (GIWAXS) to relate surface chemistry to thin-film morphology and molecular order at the surface and semiconductor-dielectric interface, respectively. Films evaporated on n-octyltrichlorosilane (OTS) yielded devices with the highest average μe of 7.2 × 10-2 cm2·V-1·s-1 that we attributed to it having both the largest domain length, which were extracted from power spectral density function (PSDF) analysis, and a subset of molecules with a pseudo edge-on orientation relative to the substrate. Films of F10-SiPc with the mean molecular orientation of the π-stacking direction being more edge-on relative to the substrate also generally resulted in OTFTs with a lower average VT. Unlike conventional MPcs, F10-SiPc films fabricated by WEG experienced no macrocycle in an edge-on configuration. These results demonstrate the critical role of the F10-SiPc axial groups on WEG, molecular orientation, and film morphology as a function of surface chemistry and the choice of SAMs.

The Effect of Electro-Induced Multi-Gas Modification on Polymer Substrates’ Surface Structure for Additive Manufacturing

We investigated the effect of electro-induced multi-gas modification (EIMGM) duration on the adhesion and wear resistance of PET and LDPE polymer substrates used in the printing industry. It was found that EIMGM increases the polar component and the complete free surface energy from 26 to 57 mJ/m2 for LDPE and from 37 to 67 mJ/m2 for PET (due to the formation of oxygen-containing groups on the surface of the materials). Although the degree of textural and morphological heterogeneity of the modified LDPE increased more than twice compared to the initial state, it is not still suitable for application as a substrate in extrusion 3D printing. However, for PET, the plasma-chemical modification contributed to a significant increase (~5 times) in filament adhesion to its surface (due to chemical and morphological transformations of the surface layers) which allows for using the FFF technology for additive prototyping on the modified PET-substrates.

Symmetric expressions of surface tension components

ABSTRACT Surface tensions of solid materials have been studied over 200 years and widely used for industrial or engineering applications. The surface tensions and surface tension components can be calculated using measured contact angles, for example, by the model studied by Owens and Wendt. The model is often represented in an asymmetric linear form, called the Owens-Wendt-Rabel-Kaelble method, with the use of the linear least squares method. However, due to the practical preference not to use many types of test liquids, the existing statistical analysis is unsuitable, especially when the data measured are scattered. The present work proposes symmetric linear and circular expressions of the model of the two surface tension components. The symmetric linear expression can be used for obtaining the polar and dispersion components of surface tension of a solid; it enables appropriate choices for test liquids, physically meaningful screening of measured values, and clear validation of deduced surface tension components of solids. The symmetric circular expressions can be applied to deduce polar and dispersion components of liquids by using test solids. In conjunction with this, appropriate choices of test solids can be determined.

Design and calibration of a Mueller matrix microscope based on liquid crystal variable retarders

Polarization imaging techniques have achieved broad applications in areas such as material characterization, nano-scale measurement, and biomedical diagnosis. The Mueller matrix microscopy, as one of the polarization imaging techniques, can provide the most comprehensive polarization information of a sample, such as anisotropy and depolarization. However, the instrumentation of Mueller matrix microscopy is typically complex and the associated calibration process is usually difficult due to the presence of many polarization and imaging components. In this work, we present an easy-to-follow approach for the instrumentation of Mueller matrix microscopy, not from scratch, but by easily modifying a commercial microscope into a Mueller matrix microscope (MMM) based on liquid crystal variable retarders (LCVR). Optimal configurations have been generated by the genetic algorithm at wavelengths of 400-800 nm. An extended eigenvalue calibration method is proposed to accurately calibrate the polarization and imaging components of the modified instruments in a model-free approach. Experiments performed on standard samples at the wavelength of 532nm, such as a polarizer and a waveplate, have indicated the performances of the developed MMM with a measurement error of less than 0.01 and a mean standard deviation of around 0.0042.

Effect of Polar Hydrocarbon Contents on Oil-Water Interfacial Tension and Implications for Recent Observations in Smart Water Flooding Oil Recovery Schemes.

For decades now, low salinity water flooding (LSWF) oil recovery has emerged as an environmentally benign and cost-effective method for improved oil recovery, where research findings have reported pH and interfacial tension effects. Considering the effect of oil chemistry on interfacial tension and the potential of this chemistry to have a direct relationship with LSWF, we measured the interfacial tension of four crude oils with composition varying from those of conventional to unconventional ones. We also characterized the crude oil samples using infrared spectroscopy and a wet chemistry method based on asphaltene precipitation. Our research approach has enabled us to relate the composition of crude oil to the interfacial tension trend at pH encountered in improved oil recovery schemes. Our research methodology, based on an integrated approach to using infrared spectroscopy and interfacial tensiometry, has also enabled us to propose a more robust theoretical explanation for current observations in LSWF related to pH and interfacial tension. In this regard, oil-water interfacial tension depends on the concentration of polar components, such that the higher the concentration of polar groups in crude oil, the higher the interfacial tension at a given pH of aqueous solution. We have also shown that the acid-base behavior of polar groups at the oil-water interface provides a theoretical interpretation of the explicit relationship between oil-water interfacial tension and the electrostatic components of interfacial tension as given by the energy additivity theory.

Enhanced Spin Current in Ni81 Fe19 /Cu-CuOx Bilayer with Top and Sideways Oxidization.

Generation and manipulation of spin current are the cores of spintronic devices, which are intensely pursued. Heavy metals with strong spin-orbit coupling are commonly used for the generation of spin current, but areincompatible with the mass production of devices, and the polarization of spin current is limited to be in-plane. Here, it is shown that the spin current with strong out-of-plane polarization component can be generated and transmitted in Ni81 Fe19 /Cu-CuOx bilayer with sideways and top oxidizations. The charge-to-spin current conversion efficiency can be enhanced through the spin currents consisting of both out-of-plane polarization (σz ) and in-plane polarization (σy ) induced by spin-vorticity coupling. Such a spin current is demonstrated to be closely related to the lateral oxidization gradient and can be controlled by changing the temperatures and times of annealing. The finding here provides a novel degree of freedom to produce and control the spin current in spintronic devices.

The catalytic activity and structure of the lipid metabolizing CYP124 cytochrome P450 enzyme from Mycobacterium marinum

The CYP124 family of cytochrome P450 enzymes, as exemplified by CYP124A1 from Mycobacterium tuberculosis, is involved in the metabolism of methyl branched lipids and cholesterol derivatives. The equivalent enzyme from Mycobacterium marinum was investigated to compare the degree of functional conservation between members of this CYP family from closely related bacteria. We compared substrate binding of each CYP124 enzyme using UV–vis spectroscopy and the catalytic oxidation of methyl branched lipids, terpenes and cholesterol derivatives was investigated. The CYP124 enzyme from M. tuberculosis displayed a larger shift to the ferric high-spin state on binding cholesterol derivatives compared to the equivalent enzyme from M. marinum. The biggest difference was observed with cholesteryl sulfate which induced distinct UV–vis spectra in each CYP124 enzyme. The selectivity for oxidation at the ω-carbon of a branched chain was maintained for all substrates, except cholesteryl sulfate which was not oxidized by either enzyme. The CYP124A1 enzyme from M. marinum, in combination with farnesol and farnesyl acetate, was structurally characterized by X-ray crystallography. These ligand-bound structures of the CYP124 enzyme revealed that the polar component of the substrates bound in a different manner to that of phytanic acid in the structure of CYP124A1 from M. tuberculosis. However, closer to the heme the structures were similar providing an explanation for the high selectivity of the enzyme for terminal methyl C–H bond oxidation. The work here demonstrates that there were differences in the biochemistry of the CYP124 enzymes from these closely related bacteria.

Creation of pure longitudinal super-oscillatory spot.

We present a method that creates a super-oscillatory focal spot of a tightly focused radially polarized beam using the concept of a phase mask. Using vector diffraction theory, we report a super-oscillatory focal spot that is much smaller than the diffraction limit and the super-oscillation criterion. The proposed mask works as a special polarization filter that enhances the longitudinal component and filters out the transverse component of radial polarization at focus, permitting the creation of a pure longitudinal super-oscillatory focal spot.

Aging of Polylactide Films Exposed to Plasma—Hydrophobic Recovery and Selected Application Properties

In this study, the effect of polylactide (PLA) material on the susceptibility to hydrophobic recovery due to storage was examined, the effectiveness of plasma activation of the film, defined as improving the hydrophilicity of the material, was studied, and the selected film properties that are important from an application point of view were investigated. The study was conducted on three films using oxygen and argon plasma. Contact angles of water, diiodomethane, and ethylene glycol were investigated, and the values of surface free energy (SFE) and its polar and dispersive components were determined immediately after activation, as well as after a specified storage time (after 1, 7, 14, 30, and 60 days). The effects of film activation on its roughness, weight loss, tensile strength, color changes, and gloss were also determined. Based on the results, it was concluded that the type of film influences the course of hydrophobic recovery. At the same time, the trend of changes depends on the type of gas used for activation, while the magnitude of changes depends on the film. Moreover, it was observed that the type of PLA film had a significant effect on the changes in the polar and dispersion components of SFE, as well as on roughness and mass loss due to plasma activation. Furthermore, these parameters also depended on the type of gas used for plasma activation.

Moisture susceptibility evaluation of zeolite-foamed asphalts based on the Surface Free Energy (SFE) concept

Zeolite-Foamed Asphalt (ZFA), as a typical-used Warm Mix Asphalt (WMA) in practice, has significant advantages in environmental friendliness and construction convenience, but its moisture susceptibility is relatively weak. Most of the existing research regarding its moisture susceptibility was carried out by performing macroscopic tests, which are incapable of providing theoretical bases for moisture susceptibility optimisation. This article studies the moisture susceptibility of ZFA from a mesoscopic perspective based on the Surface Free Energy (SFE) concept. To determine the SFE of each composition, sessile drop tests were first conducted on three types of aggregates (i.e., basalt, diabase and granite) and three types of bitumen binder (i.e., virgin binder, SBS modified binder and rubber modified binder), respectively, considering four different zeolite incorporation contents (i.e., 0%, 3%, 6% and 9% by the binder mass). Several SFE-based factors, including work of cohesion, dry work of adhesion, work of debonding, spreading coefficient and a SFE-related energy ratio (EP1), were calculated. These factors were correlated with the mass loss ratio of the binder-aggregate systems obtained through boiling water stripping tests to validate their feasibility in evaluating the moisture susceptibility of ZFA. The results indicate that the increase of the polar component and the decrease of the dispersion component of the binder’s SFE resulting from the zeolite foaming process affect the moisture susceptibility of the ZFA either positively or negatively, depending on the dominated failure mode and the aggregate’s SFE. An aggregate with a higher polar component of the SFE, such as the granite in the present work, is more recommended for preparing ZFA when an interfacial adhesion failure occurs. Dry work of adhesion and EP1 demonstrate good correlations with the mass loss ratios and the correlation coefficients are not lower than 0.8057. ZFA prepared with the rubber-modified binder, granite and 9% zeolite is suggested in the present work. The results can theoretically guide the optimisation of the moisture susceptibility of ZFA in practice.

Investigation of graphite tailings as a substitute for filler in asphalt mastics

ABSTRACT As a solid waste, graphite tailings (GTs) have caused serious harm to the environment and nearby residents, and using GTs as pavement materials can not only solve the environmental problems but also promote sustainable pavements. To this end, this study experimentally explored the feasibility of using three kinds of GTs (named GT-A, GT-H, and GT-W) as fillers to prepare asphalt mastics and analysed their micro properties, mechanical properties, asphalt-filler interaction, and dielectric properties. The results show that graphite tailings asphalt mastics (GTAMs) have less bee-like structures, which causes greater average adhesion compared with limestone asphalt mastic (LAM). Besides, because GTs have a rougher micromorphology, a larger particle size, a greater density, a higher specific surface area, and a stronger interaction with asphalt than those of limestone, they exhibit better mechanical properties than LAM. Further, GTAMs possess superior dielectric properties than LAM due to the chemical composition of GTs, which contains more polar components than limestone. Among the three GTAMs, GTAM-A has the best overall performance, followed by GTAM-H, and then GTAM-W. This study proposes a feasible solution for the comprehensive recycling and reuse of GTs as raw materials for sustainable asphalt pavements while lowering economic and environmental costs.

Foamed crumb rubber asphalt binder: Preparation, rheological properties and adhesion characteristics

In this study, the rheological properties and adhesion characteristics of foamed CRA binder were studied. Firstly, the optimum foaming conditions of foamed CRA binder with different crumb rubber powder (CRP) content and foaming agent were studied. Secondly, stress creep recovery (MSCR) test, temperature scanning and frequency scanning tests were carried out by using dynamic shear rheometer (DSR), and the high temperature performance, temperature sensitivity and viscoelastic characteristics of each asphalt binder sample before and after aging were studied. Finally, the surface free energy theory was used to evaluate the adhesion characteristics of each sample. The results showed that the commonly used foaming agent cetyl trimethyl ammonium bromide has no effect on the foaming of CRA binder. With the increase of CRP content, the foaming temperature became higher, and it was difficult to foam successfully when the rubber powder content was higher than 15%. Increasing the content of CRP in a certain range can improve the high temperature performance and adhesion of foamed CRA binder and reduce its temperature sensitivity. With the aging process of the sample, the high temperature performance of foamed CRA binder increased, and the temperature sensitivity and adhesion characteristics decreased. The surface free energy of foamed CRA binder is mainly composed of dispersion component, and the polarity component is relatively small. The surface free energy of foamed CRA binder increased with the increase of CRP content. In addition, foaming agent B (water-in-oil emulsifier) would reduce the temperature sensitivity and high-temperature performance of foamed CRA binder, but it had no obvious effect on adhesion.

Surface modification of the Nylon 6,6 and wasted glass fiber‐Nylon 6.6 coatings using atmospheric plasma treatment

AbstractPolymers tend to have low surface free energy, a significant cause of adhesion properties with other substances. Plasma treatment is an optimal method to improve surface properties. This work used a recycled glass fiber‐polymer coating, and another based on Nylon 6,6. The surface modification of both layers was carried out with an atmospheric plasma treatment at different times. Chemical analysis of the plasma treated and the untreated surface were analyzed by infrared spectroscopy and X‐ray diffraction. Atomic force microscopy (AFM) investigated the morphology and topography surface. The plasma treatment results improve wettability and surface free energy. The contact angle decreases for Nylon 6,6 from 68° to 0° and for glass fiber‐polymer from 56° to 18°. However, the wettability remains over time in Nylon 6,6 layer, and the composite material reverts in 15 days. The high surface free energy after plasma treatment was mainly due to an increase in the polar component by inserting polar groups. The % crystallinity increases with plasma treatment due to the loss of the amorphous part of the polymer by plasma etching. AFM analysis shows an improvement in the roughness surface after treatment. These results greatly interest in enhancing adhesion with other substrates.

Green Automated Solid Phase Extraction to Measure Levofloxacin in Human Serum via Liquid Chromatography with Fluorescence Detection for Pharmacokinetic Study

A simple, selective, rapid, sensitive and less costly green automated solid phase extraction bio-analytical high-performance liquid chromatographic-based technique with fluorescence detection (Aut-SPE-BA-HPLC-FL) for the quantification of levofloxacin in human serum samples has been developed and validated. The serum samples were loaded into the chromatographic system without prior treatment and then injected into short (20 mm × 4.6 mm, 20 µm) protein-coated (PC) µBondapak CN (µBCN) silica pre-column (PC-µBCN-pre-column). Levofloxacin was retained and pre-concentrated on the head of the PC-µBCN-pre-column, while proteins and other polar components were eliminated using phosphate buffer saline (PBS), pH 7.4, as the first mobile phase in the extraction step. Levofloxacin is then transferred to the analytical column; ZORBAX Eclipse XDB-C18 (150 mm × 46 mm, 5 µm), through the aid of a column-switching valve technique, on-throughs the elution mode using the second mobile phase containing a methanol and phosphate buffer (0.05 M, pH 5) in a ratio of 70:30 (v/v). Levofloxacin signals were detected using a fluorescence detector operated at excitation/emission wavelengths of 295/500 nm. The proposed Aut-SPE-BA-HPLC-FL methodology showed linearity over a levofloxacin concentration range of 10–10,000 ng/mL (r2 = 0.9992), with good recoveries ranging from 87.12 to 97.55%. Because of the validation qualities in terms of linearity, recovery, precision, accuracy, selectivity and robustness, the Aut-SPE-BA-HPLC-FL method has been used in some clinical trials for therapeutic drug monitoring and the pharmacokinetic study of levofloxacin in human serum.

Wideband and function-switchable polarization converter based on multi-mode active metasurface

A linear polarization converter based on multi-mode active metasurface is proposed to achieve wideband/dual-band, function-switch, low profile, filter and reflection, including two slot-loaded right-angle triangular resonators connected by two PIN diodes. The switchable function of the linear polarization converter between wideband and dual-band is realized by controlling the OFF/ON states of the diodes. By detailed analysis of the field/current distribution and polarization components in different modes of the multi-mode resonator unit, the filtering characteristic and magnetic-resonant-based polarization conversion mechanism between wideband and dual-band are revealed. A function-switchable filtering reflective linear polarization converter is designed, fabricated, and measured, presenting single bandwidth of 6.43–10.16 GHz, dual bandwidths of 6.08–6.39 GHz, and 11.7–12.54 GHz in the OFF- and ON-state, respectively. In both states, the polarization conversion ratios both exceed 90 %. Results show that the proposed reflective linear polarization converter has excellent switchable function, low profile and filtering linear polarization conversion.

Effect of carbon fiber surface properties on carbon fiber/polyphenylene sulfide composite interfacial property

AbstractCarbon fiber (CF) reinforced polyphenylene sulfide (PPS) composite shows extraordinary thermal stability, chemical resistance, and processability. The interface between CF and PPS transfers the load, and its properties are crucial to determine composite properties such as mechanical performance, reliability, and so forth. This work explores the relationship between surface properties of CFs (with/without sizing layer) and the interfacial properties of CF/PPS composite. X‐ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscope were employed to evaluate surface physicochemical properties of CFs, and reveal the increasing roughness and decreasing content of functional groups on the CF surface after desizing. Inverse gas chromatography and dynamic contact angle tests were adopted to characterize the surface energy of CFs, and present that the dispersive component of surface energy increases, while the polar component decreases, and the total surface energy is barely changed after desizing. Differential scanning calorimetry measurement reveals the increasing crystallinity of CF/PPS after CF desizing. Microbond test was performed to analyze interfacial shear strength (IFSS) of CF/PPS, displays that IFSS keeps almost constant after CF desizing. The results demonstrate that the surface energy of CF is important to the interfacial crystallinity, but not the critical factor for interfacial strength of CF/PPS composite.

Valorization of Lyophilized Olive Mill Wastewater: Chemical and Biochemical Approaches

Lipid composition and antioxidant activity have been carried out in order to valorize the composition of olive mill wastewater extracts with different solvents (supercritical carbon dioxide, n-hexane, dichloromethane and ethanol). The antioxidant activity was evaluated using ABTS (2,2′-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH (2,2-diphenyl-1-picrylhydrazyl) tests. The total phenolics and flavonoid contents were, also, determined. The chemical composition of the extracted oil was established, respectively, by gas chromatography–flame ionization detector and high-performance liquid chromatography methods. The results showed that the oleic acid and equivalent carbon number of forty-eight were the major compounds of the analyzed oils. Residual olive mill wastewater from the Sousse region displayed the highest DPPH radical-scavenging activity (31.10 ± 0.10 μg/mL). The chemical analysis of extracts of OMWs showed that the n-hexane fraction contained an abundance of oleic acid (61.62%) and an equivalent carbon number of forty-eight (53.14%). The best antioxidant activity was determined for the ethanol fraction (14.5 μg/mL). The final results showed a significant difference and variations in polar and apolar components. Moreover, n-hexane extracts showed high percentages of Monounsaturated fatty acids (MUFA) with 64% of OMWs oil composition and the dichloromethane extracts contained the largest amount of flavonoids (160.30 ± 1.70 mg EQ/g DM).