Polarized Light Microscopy Research Articles

Investigating the coking performance of ethylene residue pitch components

Ethylene residue pitch (ETP, the heavy component in ethylene residue tar) is widely used as a preferred raw material for preparing petroleum-based artificial carbon materials characterized by high carbon content, high aromaticity, and low heteroatom (S, N) content. To investigate the coking properties of ETP, eight components of ETP (four soluble and four insoluble components) were obtained via extraction and separation using methanol, n-butanol, n-hexane, and dimethyl sulfoxide as solvents. The thermal conversion (temperature = 500 °C) and carbonization treatment (temperature =1400 °C) were carried out on each pitch component. The basic physical properties of ETP components were observed using infrared spectroscopy, thermogravimetric analysis, and 1H-NMR. The microstructure of the petroleum-based pitch coke was studied using polarizing microscopy, X-ray single crystal diffraction (XRD), Raman spectroscopy, and scanning electron microscopy. The aromaticity of the insoluble components in ETP was slightly higher than that of soluble components, and the insoluble components had slightly fewer branching chains than those in soluble components. The microstrength of the ETP coke obtained using insoluble components was higher than that obtained using soluble components, and the true density of ETP coke HS-C was as high as 2.0554 g/cm3.

Eicosatetraynoic Acid Regulates Pro-Fibrotic Pathways in an Induced Pluripotent Stem Cell Derived Macrophage:Human Intestinal Organoid Model of Crohn's Disease.

We previously identified small molecules predicted to reverse an ileal gene signature for future Crohn's Disease (CD) strictures. Here we used a new human intestinal organoid (HIO) model system containing macrophages to test a lead candidate, eicosatetraynoic acid (ETYA). Induced pluripotent stem cell lines (iPSC) were derived from CD patients and differentiated into macrophages and HIOs. Macrophages and macrophage:HIO co-cultures were exposed to lipopolysaccharide (LPS) with and without ETYA pre-treatment. Cytospin and flow cytometry characterized macrophage morphology and activation markers, and RNA sequencing defined the global pattern of macrophage gene expression. TaqMan Low Density Array, Luminex multiplex assay, immunohistologic staining, and sirius red polarized light microscopy were performed to measure macrophage cytokine production and HIO pro-fibrotic gene expression and collagen content. iPSC-derived macrophages exhibited morphology similar to primary macrophages and expressed inflammatory macrophage cell surface markers including CD64 and CD68. LPS-stimulated macrophages expressed a global pattern of gene expression enriched in CD ileal inflammatory macrophages and matrisome secreted products, and produced cytokines and chemokines including CCL2, IL1B, and OSM implicated in refractory disease. ETYA suppressed CD64 abundance and pro-fibrotic gene expression pathways in LPS stimulated macrophages. Co-culture of LPS-primed macrophages with HIO led to up-regulation of fibroblast activation genes including ACTA2 and COL1A1, and an increase in HIO collagen content. ETYA pre-treatment prevented pro-fibrotic effects of LPS-primed macrophages. ETYA inhibits pro-fibrotic effects of LPS-primed macrophages upon co-cultured HIO. This model may be used in future untargeted screens for small molecules to treat refractory CD.

Oral supplementation with probiotics, potassium citrate, and magnesium in reducing crystalluria in stone formers: A phase II study.

Crystalluria is an important indicator of renal stone recurrence. Mechanisms underlying urinary stone formation are still not fully understood and raising interests has been giving to intestinal commensal bacteria for their contribute in maintaining urinary solutes equilibrium. The aim of our phase II study was to examine the administration of potassium citrate, magnesium and probiotics in order to reduce crystalluria. Since May 2021, we enrolled 23 patients candidates for ureterorenolithotripsy for calcium oxalate kidney stones with crystalluria and a normal metabolic profile. The analysis was validated by the Institution's Ethical Committee (no. approval STS CE Lazio 1/N-823). At discharge, patients were provided with daily food supplementation for 20 days of 1 billion Lactobacillus paracasei LPC09, 1 billion Lactobacillus plantarum LP01, 1 billion Bifidobacterium breve BR03, potassium (520 mg), citrate (1400 mg), and magnesium (80 mg). Crystalluria was re-assessed at 1, 3, 6, and 12-months follow-up by polarized light microscopy. After one month from the oral supplementation, no patient reported crystalluria; at 3 months, among the 20 participants available for re-evaluation, still no patient reported crystalluria. Instead, crystalluria was reported in three patients (15%) at 6 months, and in five patients (25%) at 12 months follow-up. The oral supplementation with Lactobacillus spp. and Bifidobacterium spp. was found able to reduce the prevalence of crystalluria in a cohort of patients with diagnosis of calcium oxalate kidney stones with crystalluria candidate to ureterorenolithotripsy.

Widefield quantitative polarized light microscopy using spectrally encoded null polarimetry.

Quantitative polarized light microscopy enables determination of optical retardation and azimuth of birefringent specimens and is a powerful tool for label-free imaging in the fields of biology and pathology. We have recently proposed a device for fast laser-scanning birefringence microscopy based on a near-infrared wavelength-swept laser and spectral encoding of polarization, resulting in a channeled spectrum generated during the wavelength-sweep of the laser and highly sensitive to optical retardation [Opt. Lett.49, 387 (2024)10.1364/OL.507576]. In this Letter, we propose its transposition to visible widefield imaging using a white light source and a high-order retarder for spectral encoding and a hyperspectral camera to record the channeled spectrum at each point of the image in parallel. The method proposed here allows for straightforward conversion of any widefield microscope into a highly sensitive and quantitative polarized light microscope.

Mopa Mopa and Barniz de Pasto at the Victoria and Albert Museum: Recent Developments

This paper summarises the research carried out so far on barniz de Pasto objects from the Victoria and Albert Museum (V&A) and outlines future areas of development for our collection of Indigenous lacquer from Latin America. The V&A was the first UK public institution to identify objects decorated with barniz de Pasto within its collection. Two of these were acquired in 2015 and 2018; others had entered the collection between 1855 and 1902 but were recognised as barniz de Pasto only after 2018. The acquisition in 2015 of a cabinet marked the start of a research campaign to understand the materiality and context of all the museum’s barniz de Pasto objects. The analytical techniques used included X-radiography, polarised light microscopy and digital microscopy, Raman microscopy, X-ray fluorescence (point and scanning), chromatography (py-GC–MS and LC–DAD–MS), Fourier transform infrared spectroscopy, X-ray diffraction, and X-ray micro-computed tomography. Unexpected discoveries were made along the way, including the characterisation and documentation of mercury white (mercury(I) chloride, or calomel) used as a white pigment, a world first. Gel-based cleaning methods were used to remove a non-original, discoloured, natural varnish covering nearly the entire surface of one of the objects, and the recent overpaint on its lid, revealing original surfaces which had been repaired and drastically repainted in the second half of the twentieth century.

Synergistically controlled in situ growth of silver nanoparticles leading to organization of anisotropic liquid crystalline medium

ABSTRACT An in-depth macroscopic and microscopic investigation is carried out regarding understanding phase ordering and organisation of nematic phase of a room temperature nematic liquid crystal (NLC) MBBA (N-(4-methoxybenzylidene)-4-butylaniline) in the presence of silver nanoparticles (AgNPs) which are synthesised in situ in a single step using MBBA as a template as well as a reducing and stabilising unit. A synergistic effect between anisotropic LC structure and morphologies of AgNPs is observed. The LC-AgNP composite exhibits better thermal stability and phase ordering compared to its neat LC counterpart as indicated by combined study of optical polarization microscopy (OPM) and differential scanning calorimetry (DSC). While OPM study exhibits emergence of smectic mesophase in LC-AgNP composites, DSC manifests significant enhancement in the isotropic temperature and associated enthalpy as well as a change in the kinetic behaviour in LC-AgNP composites compared to neat LC. Also, an alternation in the electronic properties of LC-AgNP composites compared to neat LC is recognised. Such ordering at the macroscopic scale is well supported by our microscopic observations through spectroscopic studies such as Fourier transform infrared (FTIR) and X-ray diffraction (XRD) which provides valuable insights regarding understanding the organisation process more closely.

Multiresponsive Liquid Crystal Collagen Guides Mussel Byssus Formation.

Marine mussels fabricate tough collagenous fibers known as byssal threads to anchor themselves. Threads are produced individually in minutes via secretion of liquid crystalline (LC) collagenous precursors (preCols); yet the physical and chemical parameters influencing thread formation remain unclear. Here, we characterized the structural anisotropy of native and artificially induced threads using quantitative polarized light microscopy and transmission electron microscopy to elucidate spontaneous vs regulated aspects of thread assembly, discovering that preCol LC phases form aligned domains of several hundred microns, but not the cm-level alignment of native threads. We then explored the hypothesized roles of mechanical shear, pH, and metal ions on thread formation through in vitro assembly studies employing a microfluidic flow focusing device using purified preCol secretory vesicles. Our results provide clear evidence for the role of all three parameters in modulating the structure and properties of the final product with relevance for fabrication of collagenous scaffolds for tissue engineering applications.

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.

Deep Learning‐Based Classification of Histone–DNA Interactions Using Drying Droplet Patterns

Developing scalable and accurate predictive analytical methods for the classification of protein‐DNA binding is critical for advancing our understanding of molecular biology, disease mechanisms, and a wide spectrum of biotechnological and medical applications. It is discovered that histone–DNA interactions can be stratified based on stain patterns created by the deposition of various nucleoprotein solutions onto a substrate. In this study, a deep‐learning neural network is applied to categorize polarized light microscopy images of drying droplet deposits originating from different histone–DNA mixtures. These DNA stain patterns featured high reproducibility across different species and thus enabled comprehensive DNA categorization (100% accuracy) and accurate prediction of their respective binding affinities to histones. Eukaryotic DNA, which has a higher binding affinity to mammalian histones than prokaryotic DNA, is associated with a higher overall prediction accuracy. For a given species, the average prediction accuracy increased with DNA size. To demonstrate generalizability, a pre‐trained CNN is challenged with unknown images that originated from DNA samples of species not included in the training set. The CNN classified these unknown histone‐DNA samples as either strong or medium binders with 84.4% and 96.25% accuracy, respectively.

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.