Polarized Light Microscopy Research Articles

Formation of subwavelength tunable flat-top focus with double foci characteristic by tightly focused cylindrical vector beams

We report a numerical investigation on the generation of a subwavelength flat-top focus by tuning the polarization angle of the incident beam under tight focusing conditions. Our approach uses a binary phase mask containing two regions of opposite phases, with a variable diameter of the inner region. Properly tuning the diameter of the inner region of the mask, the flat-top profile of variable sizes (above and below the subwavelength region) is generated in a controlled manner with the various incident polarization angles of the beam and with the different numerical aperture (NA) value of the lens. Our study reveals that a particular cut-off value of polarization angle, above which the subwavelength flat-top is generated, corresponds to a specific NA that increases with the increase in the NA value. In addition, the emergence of the dual foci structure is observed in the longitudinal direction with increasing NA of the lens. The flat-top's polarization degrees-of-freedom and dual foci properties open up promising routes for potential applications in fluorescence polarization microscopy and multiplane particle trapping.

Preparation, Characterization and Evaluation of Nintedanib Amorphous Solid Dispersions with Enhanced Oral Bioavailability.

The dissolution and bioavailability challenges posed by poorly water-soluble drugs continue to drive innovation in pharmaceutical formulation design. Nintedanib (NDNB) is a typical BCS class II drug that has been utilized to treat idiopathic pulmonary fibrosis (IPF). Due to the low solubility, its oral bioavailability is relatively low, limiting its therapeutical effectiveness. It is crucial to enhance the dissolution and the oral bioavailability of NDNB. In this study, we focused on the preparation of amorphous solid dispersions (ASD) using hot melt extrusion (HME). The formulation employed Kollidon® VA64 (VA64) as the polymer matrix, blended with the NDNB at a ratio of 9:1. HME was conducted at temperatures ranging from 80°C to 220°C. The successful preparation of ASD was confirmed through various tests including polarized light microscopy (PLM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The in-vitro cumulative release of NDNB-ASD in 2h in a pH 6.8 medium was 8.3-fold higher than that of NDNB (p < 0.0001). In a pH 7.4 medium, it was 10 times higher (p < 0.0001). In the in-vivo pharmacokinetic experiments, the area under curve (AUC) of NDNB-ASD was 5.3-fold higher than that of NDNB and 2.2 times higher thanthat of commercially available soft capsules (Ofev®) (p < 0.0001). There was no recrystallization after 6months under accelarated storage test. Our study indicated that NDNB-ASD can enhance the absorption of NDNB, thus providing a promising method to improve NDNB bioavailability in oral dosages.

The influence of temperatures on the mechanical properties and fracture behavior of rocks under mixed mode I/II loading

A comprehensive understanding of the fracture behavior of pre-heated rocks under to mixed mode I/II loading is crucial for deep underground engineering. The effect of high temperature on the fracture process zone (FPZ) and fracture toughness of rocks was experimentally investigated using semi-circular bend (SCB) samples. Surface displacement and associated strain field under loading were captured using digital image correlation. The results showed that the mechanical properties of SCB samples gradually decreased with increasing temperature. Rocks exposed at temperature exceeding 600 °C demonstrated a significant reduction in peak load, generalized stiffness, fracture toughness, and absorbed energy. Moreover, the load–displacement curves and macroscopic fracture characteristics of pre-heated SCB samples revealed a transition from brittleness to ductility with increasing temperature under mixed mode I/II loading. Both the length and width, as well as the crack tip opening displacement of the FPZ, increased with rising temperature. At lower temperatures (25 ∼ 400 °C), the ratio of FPZ length to width typically ranged between 2 and 3. While, at elevated temperature (600 ∼ 1000 °C), this ratio expanded to between 3 and 4. The initiation of thermally induced cracks in rocks will accelerate damage evolution under mixed mode I/II loading, as indicated by the development of the maximum principal strain with displacement. Scanning electron microscopy and polarization microscopy images of the microscopic fracture morphology in pre-heated rocks illustrated isolated and dispersed microcracks appeared at lower temperatures, whereas at elevated temperatures, intricate microcrack networks and broken grains were observed.

OOPS: Object-Oriented Polarization Software for analysis of fluorescence polarization microscopy images.

Most essential cellular functions are performed by proteins assembled into larger complexes. Fluorescence Polarization Microscopy (FPM) is a powerful technique that goes beyond traditional imaging methods by allowing researchers to measure not only the localization of proteins within cells, but also their orientation or alignment within complexes or cellular structures. FPM can be easily integrated into standard widefield microscopes with the addition of a polarization modulator. However, the extensive image processing and analysis required to interpret the data have limited its widespread adoption. To overcome these challenges and enhance accessibility, we introduce OOPS (Object-Oriented Polarization Software), a MATLAB package for object-based analysis of FPM data. By combining flexible image segmentation and novel object-based analyses with a high-throughput FPM processing pipeline, OOPS empowers researchers to simultaneously study molecular order and orientation in individual biological structures; conduct population assessments based on morphological features, intensity statistics, and FPM measurements; and create publication-quality visualizations, all within a user-friendly graphical interface. Here, we demonstrate the power and versatility of our approach by applying OOPS to punctate and filamentous structures.

Novel Biobased Copolymers Based on Poly(butylene succinate) and Cutin: In Situ Synthesis and Structure Properties Investigations.

The present work describes the synthesis of poly(butylene succinate) (PBSu)-cutin copolymers by the two-stage melt polycondensation method, esterification and polycondensation. Cutin was added in four different concentrations, 2.5, 5, 10, and 20 wt%, in respect to succinic acid. The obtained copolymers were studied using a variety of techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy (PLM), as well as diffuse reflectance spectroscopy (DRS). A series of results, in agreement between different techniques, revealed the formation of PBSu-cutin interactions, confirming indirectly the successful in situ synthetic route of copolymers. DSC and XRD combined with PLM results provided indications that the crystallization temperature increases with the addition of small amounts of cutin and gradually decreases with increasing concentration. The crystallization process was easier and faster at 2.5%, 5%, and 10% concentrations, whereas at 20%, it was comparable to neat PBSu. The presence of cutin, in general, leads to the facilitated crystallizability of PBSu (direct effect), whereas a moderate drop in the glass transition temperature is recorded, the latter being an indirect effect of cutin via crystallization. The thermal stability improved in the copolymers compared to neat PBSu. Water contact angle measurements confirmed that the addition of cutin decreased the hydrophilicity. The local and segmental relaxation mapping is demonstrated for PBSu/cutin here for the first time. Enzymatic hydrolysis and soil degradation tests showed that, overall, cutin accelerated the decomposition of the polymers. The copolymers may be proven useful in several applications.

Supporting Examinations for Hair Disorders

Hair evaluation methods are grouped into three main categories: non-invasive methods (for example: questionnaire, daily hair counts, standardized wash test, 60-s hair count, global photographs, dermoscopy, hair weight, contrasting felt examination, phototrichogram, TrichoScan, and polarizing and surface electron microscopy), semi-invasive methods (for example: trichogram and unit area trichogram), and invasive methods (for example: scalp biopsy). This article explores supporting examinations for the diagnosis of hair disorders.

Three-dimensional fiber orientation mapping of the human brain at micrometer resolution.

The accurate measurement of three-dimensional (3D) fiber orientation in the brain is crucial for reconstructing fiber pathways and studying their involvement in neurological diseases. Comprehensive reconstruction of axonal tracts and small fascicles requires high-resolution technology beyond the ability of current in vivo imaging (e.g. diffusion magnetic resonance imaging). Optical imaging methods such as polarization-sensitive optical coherence tomography (PS-OCT) and polarization microscopy can quantify fiber orientation at micrometer resolution but have been limited to two-dimensional in-plane orientation or thin slices, preventing the comprehensive study of connectivity in 3D. In this work we present a novel method to quantify volumetric 3D orientation in full angular space with PS-OCT. We measure the polarization contrasts of the brain sample from two illumination angles of 0 and 15 degrees and apply a computational method that yields the 3D optic axis orientation and true birefringence. We further present 3D fiber orientation maps of entire coronal cerebrum sections and brainstem with 10 μm in-plane resolution, revealing unprecedented details of fiber configurations. We envision that our method will open a promising avenue towards large-scale 3D fiber axis mapping in the human brain as well as other complex fibrous tissues at microscopic level.

Live imaging of center of calcification formation during septum development in primary polyps of Acropora digitifera

Recent studies have revealed that stony corals create their extracellular skeletons via biologically controlled calcification, in which amorphous calcium carbonate (ACC), regarded as precursors of aragonite crystals, have been observed at nanoscale using electron microscopy. However, the exact mechanism by which ACC is generated, and how it contributes to skeletal growth in coral calcifying tissue, remains enigmatic. The septal skeleton of an individual polyp is composed of radially aligned plates extending upward from the aboral calcifying tissue. This structure includes microstructure known as the centers of calcification (CoC). However, despite its importance, direct in vivo observation of septal growth has not been reported. Observations under transmitted illumination using polarized light microscopy on calcifying tissue of young Acropora digitifera revealed small crystals, a few micrometers in size, that accompany subtle movements and that emerge exclusively on the inner wall of the pocket in extracellular calcifying fluid (ECF). Crystal growth initiated from small, scattered crystals on a glass plate resembles this phenomenon observed in coral skeletons. Time-lapse photographs of 12 individuals in early primary polyp settlement revealed this process in three individuals, documenting 13 of these crystal events. This phenomenon occurred solely at the bases of subsequently formed septa. These crystals differ notably from fusiform crystals and from dumbbell-like or rod-like crystals growing individually. Upright two-photon microscopy captured movement of sub-micron-sized fluorescent calcein-accumulating particles, emphasizing their presence on the surface of the growing fronts of septa. Methodological advances that facilitate comprehensive in vivo observation of sub-micron-sized structures, calcein-accumulating particles to the skeleton, are needed to develop a more detailed understanding of coral skeletal growth.

Micron-resolution fiber mapping in histology independent of sample preparation.

Detailed knowledge of the brain's nerve fiber network is crucial for understanding its function in health and disease. However, mapping fibers with high resolution remains prohibitive in most histological sections because state-of-the-art techniques are incompatible with their preparation. Here, we present a micron-resolution light-scattering-based technique that reveals intricate fiber networks independent of sample preparation for extended fields of view. We uncover fiber structures in both label-free and stained, paraffin-embedded and deparaffinized, newly-prepared and archived, animal and human brain tissues - including whole-brain sections from the BigBrain atlas. We identify altered microstructures in demyelination and hippocampal neurodegeneration, and show key advantages over diffusion magnetic resonance imaging, polarization microscopy, and structure tensor analysis. We also reveal structures in non-brain tissues - including muscle, bone, and blood vessels. Our cost-effective, versatile technique enables studies of intricate fiber networks in any type of histological tissue section, offering a new dimension to neuroscientific and biomedical research.

Effect of ultrasonic pretreatment on antifreeze activity of gluten antifreeze polypeptide

In this study, the effects of thermal hysteresis activity, ice recrystallization inhibition, amino acid composition and surface hydrophobicity of different ultrasonic pretreatments on gluten antifreeze polypeptide was studied.The results of the thermal hysteresis activity showed that the collaborative (flat-panel combined probe) ultrasonic working mode was superior to the single-frequence ultrasound mode. In the optimal working mode (15 min, 100 W/L), the results of polarized light microscope and gel chromatography column showed that ultrasonic pretreatment could effectively inhibit the growth of ice crystals, reduced the size of ice crystals, and to a certain extent, transfer the molecular weight distribution of peptides to small molecular peptides. The molecular weight was mainly concentrated at about 200–1000 u. The contents of Valine, Methionine, Leucine, Proline and Glutamic acid residues in the gluten antifreeze polypeptide pretreated by ultrasonic wave were relatively high and more hydrophobic groups were exposed. The secondary structure results showed that the molecular conformation of the polypeptide was mainly α-helix and β-sheet conformations.This paper systematically revealed the intrinsic correlation mechanism between the changes of key domains of substrate proteins and the antifreeze activity of enzymatic hydrolysis products assisted by ultrasoud, providing a theoretical basis for the preparation of antifreeze polypeptide.

Investigation properties of ultra-high performance concrete incorporating pond ash

Abstract The study aims to substitute river sand used in ultra-high performance concrete (UHPC) with pond ash (PA), a waste by-product from the Sikka thermal power station in Gujarat, India, at replacement levels ranging from 0 to 20%. Also, 20% of the cement was replaced with ground granulated blast-furnace slag, which is a sustainable, eco-friendly material. As a result, this concrete is both environmentally and economically feasible. Experimental analysis evaluated the workability, compressive strength, split tensile strength, flexural strength, and microstructure of the UHPC mixtures. Incorporating 10% PA as a sand replacement enhanced the compressive strength, reaching 117 MPa at 90 days, as well as the flexural strength of 23 MPa and the split tensile strength of 14 MPa. The strength is positively impacted when 10% of the river sand is replaced with PA, while the strength of UHPC appears to be diminished if PA content is increased beyond 10% replacement of sand. Petrographic microscopy and X-ray diffraction were used to study the microstructure of UHPC made with PA. When PA was used instead of sand, the mortar mass solidified and became denser, resulting in an improved microstructure of the UHPC with fewer surface cracks. With the inclusion of PA, the calcium silica hydrate gel content of the concrete increases, and enhanced performance of UHPC up to a certain amount of replacement has been observed.

Preparation of Oxidized Pellets from Sulfuric Acid Residue Containing Zinc and Lead by Chlorination Roasting and Its Mechanism of Dezincing and Lead Removal

The utilization of sulfur acid residue is an urgent problem confronting sulfuric acid production enterprises, especially the application of sulfur acid residue (SAR) containing lead and zinc. A method combining chlorination roasting using CaCl2 with pelletizing for processing SAR containing lead and zinc was used in this study, and the effect of calcium chloride on pelletizing performance was studied; in addition, the removal behavior of lead and zinc was also studied by using polarized light microscopy (Zeiss double Axioskop 40A), X ray diffraction, SEM and EDS. The results showed that CaCl2 migrated to the surface of the pellets during drying, and this phenomenon resulted in a lower removal rate of lead and zinc inside the pellets than outside the pellets during the preheating phase. When the roasting temperature was 1220 °C, with an increase in the basicity of pellets, the silicate minerals in the pellets gradually decomposed, the hematite particles were gradually refined, and more lead or zinc minerals were exposed, which further increased the removal rate of lead and zinc in the pellets. Finally, the SAR pellets with Pb and Zn removal rates up to 91.33 and 97.88%, and a compressive strength of 2789 N, could be obtained, which is very beneficial to the sustainable development of sulfuric acid mills.

Comparative Evaluation of Zwitterionic Material, Self-assembling Peptide, and Bioactive Glass Incorporated with MI Varnish for Fluoride, Calcium, and Phosphorus Ion Release, Enamel Remineralization, and Microhardness.

White spot lesions occur when the pathogenic bacteria have broken through the enamel layer. White spot lesions (WSLs) can be treated using a complex approach. The most crucial step is to stop demineralization and biofilm formation and use assorted strategies for remineralization of lesions, thinning, microabrasion, erosion infiltration, adhesive composite resin restorations, and the bonded facets. To evaluate and compare the fluoride, calcium, and phosphorus ion release, remineralizing efficacy, and microhardness of zwitterionic material, self-assembling peptide, and bioactive glass (BGA) incorporated with MI Varnish. The original study was conducted on 60 extracted premolars; the sample size calculated was 10 per group. All samples were divided into four groups-group A, MI Varnish (control), group B, MI Varnish + zwitterionic material, group C, MI Varnish + self-assembling peptide, and group D, MI Varnish + BGA. All these groups were further evaluated and compared for fluoride, calcium, and phorphorus ion release, remineralizing efficacy, and surface microhardness (SMH). Zwitterionic material, when incorporated with MI Varnish showed high fluoride and calcium ion release and high remineralizing efficacy under polarized light microscopy (PLM). BGA, when incorporated with MI Varnish showed high phosphorus ion release and higher values in the evaluation of SMH, followed by zwitterionic material and self-assembling peptide. MI varnish alone had remineralizing properties of WSLs, but when novel materials like zwitterionic ion, self-assembling peptide, and BGA are incorporated, its efficacy increases. Among all zwitterionic ions showed superior results for fluoride and calcium ion release and remineralization and BGA for phosphorus ion release and SMH. Patil SV, Gugwad SC, Devendrappa SN, et al. Comparative Evaluation of Zwitterionic Material, Self-assembling Peptide, and Bioactive Glass Incorporated with MI Varnish for Fluoride, Calcium, and Phosphorus Ion Release, Enamel Remineralization, and Microhardness. Int J Clin Pediatr Dent 2024;17(S-1):S37-S42.

Phosphorescent Pt(II) complexes of C^N^N type tridentate ligands augmented for liquid crystallinity

ABSTRACT Using the cyclometallation reaction, Pt(II) complexes of diarylbipyridynic ligands bearing alkoxy-groups were prepared and then modified with phenylаcetylene derivatives. The target compounds were characterised by absorption and emission spectroscopy, differential scanning calorimetry, small angle X-ray scattering, polarisation microscopy, and DTF calculations. The mesomorphic properties of the obtained compounds were investigated and their liquid crystallinity was confirmed.

Push-pull biphenyl and tolane derivatives as novel luminescent liquid crystals: synthesis and properties

ABSTRACT Addressing the current challenge of high melting points and long π-conjugated skeletons in luminescent nematic liquid crystals (LCs), this study explores the incorporation of push-pull dyes with biphenyl and tolane skeletons to extend fluorescence emission wavelengths into the visible light region. We synthesised push-pull-type biphenyl and tolane derivatives incorporating alkylamino groups as donors and cyano groups as acceptors. The thermal behaviour was investigated using optical polarisation microscopy, differential scanning calorimetry and X-ray diffraction. Notably, some molecules exhibited a nematic phase. The photophysical properties of the solution and solid states were also investigated. Furthermore, we formulated a room-temperature luminescent LC by blending several LCs. Importantly, the fluorescence in the nematic phase exhibited a red-shift compared to that observed in the solution and solid states. This study demonstrates the efficacy of the push-pull structure in the design of luminescent LCs. The findings of this study hold considerable implications for the development of advanced optoelectronic devices, particularly those requiring luminescent materials with tailored properties.

Application of Polarized Light Microscopy for 3D Materials Science

Application of Polarized Light Microscopy for 3D Materials Science

Smart design of highly luminescent octupolar mesogenic tetra styryl-alkynyl bipyrimidine-based chromophores presenting non-linear optical properties

The research investigations reported in this paper focuses on the influence of rational design on the photophysical properties of new all-organic multifunctional chromophores. Nonlinear optical (NLO) behavior, optical properties and mesogenicity of several new π-conjugated octupolar chromophores, presenting alkoxy styryl-alkynyl donor groups carrying aliphatic achiral and chiral chains in the 3,4/3,5/2,4 position, connected to electron-accepting 2,2-bipyrimidine cores are investigated by various techniques (light-transmission measurements, polarized-light optical microscopy, differential scanning calorimetry measurements, two-photon excited fluorescence and Hyper Rayleigh Scattering). The mesogenic properties were investigated depending on the position of the alkoxy chain and the 3,4 derivatives were found to exhibit liquid-crystal properties with the formation columnar phases over large temperature ranges which were confirmed by small-angle X-ray scattering analysis. All the molecules exhibit exceptional high fluorescence quantum yields values around 80 % and excellent nonlinear optical properties.

Amide wax-assisted interfacial compatibilization of maleic anhydride-grafted polyethylene for high-performance wood-plastic composites

ABSTRACT The interfacial compatibility between wood fibers and plastics is one of the key problems in the preparation of high-performance wood-plastic composites (WPCs). However, the current compatibilization strategy primarily relies on a single compatibilizer, but the resulting effect is less than ideal. In this study, the combination of maleic anhydride-grafted polyethylene (MAPE) and amide wax (AW) was adopted for the synergistic compatibilization of WPCs. This approach enabled the high mobility of AW to fully penetrate the surfaces and voids of wood fibers, facilitating the interfacial migration of MAPE and resulting in strong compatibilization effects. The dual compatibilization mechanism was revealed based on the results of polarized light microscope (PLM), scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). As a consequence, the WPCs compatibilized by MAPE and AW compounds possessed better thermal stability, as well as slightly higher dynamic modulus and complex viscosity. The tensile strength and flexural strength of the WPCs reached to 55 and 45 MPa, increased by approximately 26% compared to the WPCs compatibilized by single MAPE. The dual compatibilization strategy can effectively solve poor interfacial adhesion of WPCs, enabling the preparation of high-performance and environmental-friendly WPCs, and also be readily extended to other composites.

Microscopic and histochemical characterization applied to quality control of Anacardium occidentale: Anacardium occidentale microanalyses

Anacardium occidentale belongs to the Anacardiaceae family and is popularly known as cashew. It is provided with several pharmacological activities, described in the National List of Medicinal Plants of Interest to the Unified Health System. Its anti-inflammatory, antioxidant, antimicrobial, antidiabetic, molluscicidal, and larvicidal activities stand out. As it is a plant of great economic and medicinal importance, it is necessary to characterize the pharmacobotanical profile of this species. Thus, the present work aims to carry out a microscopic and histochemical characterization applied to the quality control of A. occidentale. Cross-sections of the stem, petiole and leaf blade were performed, as well as longitudinal sections of the stem and paradermal sections of the leaf blade. Anatomical studies were performed under light, polarization and scanning electron microscopy. For histochemical analysis, different reagents were used according to the metabolite under investigation. Among the anatomical structures that provide a detailed diagnosis of the studied parts of this species, the presence of resin ducts, druse crystals, glandular trichomes, paracytic stomata, and isobilateral mesophyll stand out. Histochemistry identified the location of different substances, such as starch, phenolic compounds, lipophilic compounds, lignin, essential oils, tannins, triterpenes, steroids, and calcium oxalate crystals in the leaf blade. Through the analysis of ultra-anatomical images by SEM-EDS, it was also possible to verify that the crystals found in the leaf blade are calcium oxalate. Its elemental composition was shown in detail. In view of the results, the importance of this study is justified because important characteristics of the anatomical structure of the stem and leaves of this medicinal species of wide distribution in Brazil are now identified. They are essential parameters for the determination of botanical authenticity.

Synthesis and evaluation of Schiff base as corrosion inhibitor for carbon steel in 1 M HCl solution

PurposeThe main purpose of the present study is to introduce new Schiff bases as corrosion inhibitor for carbon steel in 1 M HCl. The inhibitory activity of Schiff base was also assessed.Design/methodology/approach2,2′-((1Z,1′Z)-((2,2-dimethylpropane-1,3-diyl)bis(azanylylidene))bis(methanylylidene))diphenol was synthesized and it’s performance as an inhibitor was then investigated in 1 M HCl. The inhibition of this compound was studied and evaluated by the chemical methods of electrochemical impedance spectroscopy, electrochemical potential dynamic polarization and Atomic Force microscopy (AFM) method. The thermodynamics parameters were investigated for corrosion of carbon steel in both the absence and presence of Schiff base.FindingsThe results of the tests showed that this compound has a good performance as an inhibitor and the percentage of inhibition on steel corrosion will increase with increasing concentration and it will reach 70% in the presence of 2 × 10−3 M of this inhibitor. Polarization tests indicated that this compound will act as a mixed inhibitor. Nyquist curves showed that the addition of this substance to the solution increased the charge transfer resistance and decreased the capacity of the double layer. The absorption of the new Schiff base on steel follows Langmuir adsorption isotherm, and the amount of free energy of adsorption indicates the spontaneous adsorption of this inhibitor. Using AFM investigations, the results of electrochemical methods were confirmed.Originality/valueIncorporation of a new Schiff base into 1 M HCl is a promising approach for protecting the carbon steel against corrosive solution.