Polarized Light Microscopy Research Articles

A Semi-Automated Machine-Learning Tool for Assessing Building Phases: Discriminant Analysis of Mortars from the 2022 Excavation at the Sarno Bath Complex in Pompeii

This study presents the results of the analyses of 15 structural mortars from the building at civ. 21, level +0 of the Sarno Bath complex in Pompeii. These samples were collected during recent stratigraphic excavations (year 2022) for detailed in-laboratory compositional characterization, aiming to trace the construction phases of the originating walls. The 2022 samples were firstly analyzed via quantitative phase analysis–X-ray powder diffraction. The resulting quantitative mineralogical profiles were then processed alongside those analyzed in previous studies from level +0 structures of the Sarno Baths using multivariate statistical methods, including principal component analysis (PCA) and discriminant analysis, applied to quantitative phase analysis (QPA)–X-ray powder diffraction data (XRPD), to identify and map the construction phases. This approach enabled the correlation of the 2022 samples with previously established construction phases. Polarized-light optical microscopy and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) were then primarily used for validation purposes. These methods highlighted the compositional differences between samples and revealed significant features related to the use of specific raw materials. These results confirm the reliability of the semi-automated sample processing proposed in this research, adopting discriminant analysis as a machine-learning-based tool for defining construction phases in Pompeian contexts.

Venetoclax Plus CyBorD Induction Therapy and Venetoclax Maintenance Treatment for Immunoglobulin Light Chain Amyloidosis with t(11;14) Translocation

Background: A total of 50% of patients with AL amyloidosis have t(11;14) translocation, allowing us to use the selective oral BCL-2 inhibitor venetoclax in their treatment. Case presentation: Our patient was admitted to the gastroenterology department due to weight loss and abdominal pain. An abdominal CT scan revealed some enlarged lymph nodes; therefore, he was referred to the hematology department. A bone marrow biopsy showed massive amorphous amyloid deposition. The sample was positive on Congo red staining and exhibited double refraction under a polarized light microscope. Serum-free light chains and the difference between involved and uninvolved free light chains (dFLCs) were elevated. Using fluorescent in situ hybridization, we detected t(11;14) translocation. Further examinations confirmed the involvement of the liver, colon and heart. Stage II AL amyloidosis was confirmed. Our patient received combined induction therapy with CyBorD and venetoclax due to the presence of the t(11;14) translocation. After six cycles, the patient achieved complete remission. Autologous stem cell transplantation (ASCT) was performed. At 100 days post-ASCT, the patient had complete hematologic remission. Venetoclax maintenance treatment was initiated. The follow-up examinations showed that the patient is in very good partial remission. Conclusions: In the case of our AL amyloidosis patient with t(11;14) translocation, the combined treatment with CyBorD and venetoclax was well tolerated and effective.

Hydrogen generation through metal waste corrosion: a systematic investigation on old/post-consumer scrap Al6063-series alloy

In this study, aluminum-based wastes are used as energy carriers for on-demand hydrogen production through sustainable, eco-friendly, and cost-effective controlled electrochemical corrosion in aqueous solution. The electrochemical process is very effective because it (i) uses waste metals to produce hydrogen, (ii) corroborates to circular economy, (iii) produces high purity hydrogen, (iv) is based on simple hydrolysis reaction of metals in relevant solutions, (v) electricity is not required and (iv) recovers part of the chemical Gibbs energy of the electrochemical corrosion usually entirely lost in the environment. We systematically studied the generation of hydrogen from industrial waste Dust Scrap Aluminum Alloy (DSAA) belonging to Al 6063 series for the first time. The process is investigated in a novel hand-made batch reactor with a low-cost commercial body suitable to an easy scale-up. Kinetics of DSAA hydrolysis reaction was explored by measuring the variation of aluminium ion concentration at different immersion times through Inductively Coupled Plasma (ICP) and weight loss measurements at different temperatures and NaOH catalyst concentrations. The effect of hydrolysis reaction on the composition and morphology of the metal surfaces in terms of formed oxide layers was studied in detail using Optical Polarizing Microscopy (OPM), Energy dispersive X-ray (EDX) and Scanning Electron Microscopy (SEM) techniques. The criteria used to evaluate the hydrogen reactor performance were hydrogen (i) yield and (ii) production rate. The experimental results showed that a strong increase in NaOH concentration (from 0.75 to 5 M) corresponding to a slow increase in hydrolysis reaction temperature (from 38.8 to 49.9 °C) lead to an improvement in hydrogen generation rate of one order of magnitude, i.e. from 35.71 to 421.41 ml/(g∙min). Low but constant rate of hydrogen can be generated for longer times at low NaOH concentrations (0.75 M), while fast and variable hydrogen generation rate occurs at higher concentrations (5 M) in short times. In the case study of Al 6063 series waste scrap, the hydrolysis reactor parameters can be regulated to deliver hydrogen generation rates from 35.71 to 421.41 ml/(g min) according to requirements. We expect that the results presented in this work will encourage researchers to study the possible use of other metal-based and multi-material plastic/metal wastes thermodynamically prone to electrochemical corrosion process as possible source of hydrogen.Graphical

Microsphere-assisted super-resolution polarized light microscopy for polarization-sensitive materials

Polarization sensitivity is a fundamental phenomenon observed in nature, and its application is vital for advancing scientific discoveries. Here, we present a microsphere-assisted polarized light microscopy method that enables high-quality, label-free super-resolution imaging of polarization-sensitive materials. We investigated the imaging performance of this method using various samples, including colloidal crystals and grating structures. Both simulations and experiments were performed to explore the underlying physical mechanisms driving the enhancement in imaging quality. The results of this work have potential values for the fields of polarized light microscopy and super-resolution imaging.

Encapsulation of Fatty Acids Using Linear Dextrin from Waxy Potato Starch: Effect of Debranching Time and Degree of Unsaturation

This study investigates the effects of the debranching time of waxy potato starch using pullulanase and recrystallization on particle morphology, debranching degree, and crystal structure. The results demonstrated that after gelatinization and debranching, the surface of the starch crystals became rough and uneven due to hydrolysis, with most particles showing a fragmented surface. The crystalline state was not significantly changed with debranching time. X-ray diffraction analysis revealed no significant differences in the patterns of recrystallized linear dextrin (LD) after various debranching times. Notably, the short-range ordered structure of LD after debranching and recrystallization was more organized than that of the original or gelatinized starch. Additionally, polarized light microscopy showed that the birefringent pattern disappeared as a result of debranching and recrystallization, indicating the breakdown of particle structure, although the overall particle morphology did not change significantly with varying debranching times. Furthermore, linear dextrin derived from starch debranched for 6 h (with pullulanase at 15 μg/g) successfully embedded stearic acid, oleic acid, and linoleic acid, forming a VI-type starch–fatty acid complex.

Granitoid Mapping with Convolutional Neural Network from ASTER and Landsat 8 OLI Data: A Case Study in the Western Junggar Orogen

The Western Junggar Orogen (Xinjiang) is featured by widespread granite intrusions and substantial Au-Cu-Mo resources, making it an ideal site to study granitoids and their metallogenic link. Here, we first conducted geological surveys and analyses with ASD spectrometry, polarized light microscopy (PLM), and X-Ray diffraction (XRD) to determine the granitoid lithology. Then, we used spectral and remote sensing data statistics and rock textural features to select band combinations from ASTER and Landsat 8 OLI VNIR-SWIR data. Three band combinations, i.e., spectral absorption bands + T1, SWIR + T1, and VNIR-SWIR + T1, serve as the input layers for convolutional neural networks (AlexNet, VGG16, and GoogLeNet). They are used for remote sensing identification of granitoid lithology and the assessment of its accuracy. The results highlight the AlexNet model’s superior performance, as evidenced by the highest weighted F1 score (91.98%) and kappa coefficient (0.84) with ASTER VNIR-SWIR + T1 as the input layers. We suggest that the AlexNet model can best identify the granitoid subtypes (with ASTER images) in the Western Junggar. In contrast, Landsat 8 OLI images performed poorly, possibly because they have only two SWIR bands. We offer detailed spatial distribution characteristics of granite subtypes and provide remote sensing exploration methods for studying polymetallic ore belts in the Central Asian Orogenic Belt (CAOB).

Hierarchically Structured Stimuli-Responsive Liquid Crystalline Terpolymer-Rhodamine Dye Conjugates.

Optically responsive materials are applied in sensing, actuators, and optical devices. One such class of material is dye-doped liquid crystal polymers that self-assemble into cholesteric mesophases that reflect visible light. We report here the synthesis and characterization of a family of linear and mildly crosslinked terpolymers prepared by the ROMP of norbornene-based monomers. The three monomers were composed of (i) rhodamine dye through one or two norbornene end groups utilizing flexible C10-alkane spacers, (ii) a cholesteryl liquid crystal (LC) using C9-alkane spacers, and (iii) PEG side chains. We investigated how these architectural variations in these terpolymers impacted their hierarchically self-assembled mesophase properties. We probed their composition, morphology, thermal, mechanic, photochromic, and mechanochromic properties using, inter alia, 1H NMR spectroscopy, DSC, temperature-dependent SAXS, diffuse reflectance UV-vis spectroscopy, and optical polarization microscopy. The new terpolymers exhibited architecture-dependent thermochromic, mechanochromic, and piezochromic properties arising from LC-rhodamine dye interactions. We found that a compromise between the rigidity and flexibility of the terpolymer architectures needed to be stricken to fully express stimuli-responsive properties. These terpolymers also showed distinctly different properties compared to those of a previously reported structurally related liquid crystalline copolymer made from two monomers. These findings help to define the design principles for optimally stimuli-responsive liquid crystalline polymers.

The Unusual Mesophases and Properties Exhibited by a Family of Glycosteroids.

In this article we describe research on the synthesis and characterization of a family of "Janus" amphiphiles composed of disaccharide head groups and alkaloid units joined together via a methylene linker, and bearing a lateral aliphatic chain of varying length. The condensed phases formed by self-organization of the products as a function of temperature were characterized by differential scanning calorimetry, thermal polarized light microscopy, and small angle X-ray scattering, allied with computational modelling and simulations. Structural studies on heating specimens from the solid showed that some homologues exhibited lamellar, columnar and bicontinuous mesophases, whereas the same homologues revealed different phase sequences on cooling from the amorphous liquid. We explore these unusual results, which are revealed via supercooling.

Evidence for Endogenous Collagen in Edmontosaurus Fossil Bone.

Reports of proteins in fossilized bones have been a subject of controversy in the scientific literature because it is assumed that fossilization results in the destruction of all organic components. In this paper, a novel combination of analytical techniques is used to address this question for an exceptionally well-preserved Edmontosaurus sacrum excavated from the Upper Cretaceous strata of the South Dakota Hell Creek Formation. Cross-polarized light microscopy (XPol) shows birefringence consistent with collagen presence. Tandem LC-MS unambiguously identified, and for the first time quantified, hydroxyproline, a unique collagen-indicator amino acid, in acid-digested samples from the Edmontosaurus. LC-MS/MS bottom-up proteomics shows identical collagen peptide sequences previously identified and reported for another hadrosaur and a T. rex sample.

Soluplus Stabilized Amorphous Dispersions for Enhanced Oral Absorption of Felodipine.

Overcoming the poor aqueous solubility of small-molecule drugs is a major challenge in developing clinical pharmaceuticals. Felodipine (FLDP), an L-type calcium calcium channel blocker, is a poorly water-soluble drug. The study aimed to explore the potential applications of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol (Soluplus) stabilized amorphous dispersions for augmenting the oral delivery of poorly water-soluble drugs. Soluplus-stabilized amorphous FLDP (FLDP-SSAs) was prepared using a two-phase mixing method. The samples were analyzed for their microscopic and macroscopic behavior using polarized light microscopy (PLM), differential scanning calorimetry (DSC), molecular simulation, and in vitro dissolution studies. Subsequently, the pharmacokinetics of FLDP-SSAs were evaluated. The maximum drug-to-Soluplus mass ratio of FLDP-SSAs was 50:50, with a drug concentration of 8.0 mg/mL. They exhibited an amorphous nature, as confirmed by PLM and DSC. FLDPSSAs generated nanoparticles with a particle size of approximately 50 nm during in vitro dissolution. Compared to FLDP oral solution, FLDP-SSAs exhibited higher solubility due to their amorphous nature and the generation of nanoparticles. The area under the curve (AUC) for oral FLDP-SSAs was 16.7-fold larger than that of the FLDP suspension. FLDP-SSAs could stabilize FLDP in an amorphous state and serve as drug carriers to enhance oral absorption.

Leveraging Optical Anisotropy of the Morpho Butterfly Wing for Quantitative, Stain-Free, and Contact-Free Assessment of Biological Tissue Microstructures.

Changes in the density and organization of fibrous biological tissues often accompany the progression of serious diseases ranging from fibrosis to neurodegenerative diseases, heart disease and cancer. However, challenges in cost, complexity, or precision faced by existing imaging methodologies and materials pose barriers to elucidating the role of tissue microstructure in disease. Here, we leverage the intrinsic optical anisotropy of the Morpho butterfly wing and introduce Morpho-Enhanced Polarized Light Microscopy (MorE-PoL), a stain- and contact-free imaging platform that enhances and quantifies the birefringent material properties of fibrous biological tissues. We develop a mathematical model, based on Jones calculus, which describes fibrous tissue density and organization. As a representative example, we analyzed collagen-dense and collagen-sparse human breast cancer tissue sections and leverage our technique to assess the microstructural properties of distinct regions of interest. We compare our results with conventional Hematoxylin and Eosin (H&E) staining procedures and second harmonic generation (SHG) microscopy for fibrillar collagen detection. Our findings demonstrate that our MorE-PoL technique provides a robust, quantitative, and accessible route toward analyzing biological tissue microstructures, with great potential for application to a broad range of biological materials.

Morphology and Immunoexpression of Selenoproteins in Term Placenta of Alpaca (Vicugna pacos) from the Peruvian Andes.

South American camelids inhabit high-altitude environments characterized by hypoxia, influencing embryonic, fetal, and placental development. This study examined the term placenta morphology of alpacas (Vicugna pacos, N = 12) and the immunoexpression of antioxidant selenoproteins (SP). We hypothesize that the placenta of alpacas, adapted to high altitudes, has characteristics with other species also adapted to altitude. Placentas were paraffin-embedded, sectioned (3-5 µm), stained with hematoxylin-eosin (H&E), Masson's trichrome, and picrosirius red, and analyzed via light and polarized light microscopy. The chorion showed simple cuboidal epithelium with binucleated cells, a subepithelial mesenchyme rich in blood capillaries (area: 124.90 ± 9.82 µm2), and type III collagen fibers. The chorionic villi measured 2740.22 ± 132.75 µm. The allantois contained a simple columnar epithelium and mesenchyme with type I collagen fibers. Immunohistochemistry localized SP-N, SP-P, Dio-3, and GPx-3 in the blood capillaries and mesenchymal tissue of the chorion but not in the allantois. These findings were compared to human and sheep placentas from different altitudes due to a lack of camelid data at low levels. The morphological features resembled adaptations to hypoxia observed in other species. This preliminary study suggests a potential role for selenoproteins in hypoxia adaptation, providing a basis for future functional studies.

Dissolution and Pharmacokinetic Studies of Paracetamol-4,4′-Bipyridine Cocrystals Obtained Using Four Methods

Paracetamol-4,4′-bipyridine cocrystals were synthesized using a solution method, reflux method, grinding method, and ultrasonic method. The structures and properties were characterized through the utilization of single-crystal X-ray diffraction (SXRD), powder X-ray diffraction (PXRD), polarized light microscopy (PLM), thermogravimetric analysis (TGA), elemental analysis (EA), and infrared spectroscopy (IR). The results show that the four methods synthesized different cocrystal morphologies, but the same structure and properties coupled with a notably high purity level. All featured strong hydrogen bonds formed between the paracetamol,4,4′-bipyridine and water molecules. An additional notable feature is the presence of π...π stacking interactions between the pyridine rings of adjacent 4,4′-bipyridine molecules. The solubility of paracetamol (active pharmaceutical ingredient, API) and the cocrystal was measured and discussed. In the dissolution experiment, the cocrystal showed a much faster dissolution rate than the API in simulated gastric fluid media (pH = 1.2). Furthermore, the pharmacokinetic (PK) behavior of the cocrystal and the API was investigated to evaluate the effectiveness of this strategy for enhancing the oral absorption of paracetamol. The in vitro and in vivo studies revealed that the paracetamol-4,4′-bipyridine cocrystal possessed an excellent dissolution behavior and an improved pharmacokinetic profile.

Comparative measurement of short-term fluoride release and inhibition of caries around restoration by ion releasing restorative materials: an in vitro study

The main objective of the current study is to compare short-term fluoride release of three ion releasing restorative materials and assess their inhibitory effect on secondary caries. Materials used in this study included, Self-adhesive hybrid composite (group A), Ion releasing flowable composite liner (group B), and alkasite restorative material (group C). Twenty-two discs were fabricated from each material for short-term fluoride release test, conducted on days 1, 7, and 14. For assessing secondary caries inhibition, sixty-six sound molar teeth were used and standardized class V cavities were prepared. Teeth were divided into three groups according to each material, followed by 800 cycles of thermocycling. Subsequently, teeth were immersed in a solution containing cariogenic bacteria for 30 days. After that, teeth were sectioned bucco-lingually and analyzed using a polarized light microscope to measure inhibition area, outer lesion depth, and extension. Data was statistically analyzed using different tests. The study results revealed a statistically significant differences in fluoride release existed among materials. Self-adhesive hybrid composite exhibited the highest fluoride release. Lesion extension and depth were statistically significantly greater next to Ion-releasing flowable composite liner. The inhibition areas next to the Self-adhesive hybrid composite were statistically significantly larger than the other two materials. In conclusion, all tested ion-releasing restorative materials displayed fluoride release and the potential to inhibit secondary caries formation. Self-adhesive hybrid composite demonstrated the highest fluoride-releasing potential and the greatest ability to inhibit secondary caries. Conversely, Ion-releasing flowable composite liner exhibited the least fluoride release with minimal secondary caries inhibition. Increasing fluoride release correlated with larger inhibition areas and reduced outer lesion depth and extension.

Collagen deposition in lung parenchyma driven by depletion of interstitial Lyve-1+ macrophages prevents cigarette smoke-induced emphysema and loss of airway function.

Collagen is essential for maintaining lung structure and function and its remodeling has been associated with respiratory diseases including chronic obstructive pulmonary disease (COPD). However, the cellular mechanisms driving collagen remodeling and the functional implications of this process in the pathophysiology of pulmonary diseases remain poorly understood. To address this question, we employed Lyve1wt/cre ; Csf1rflox/flox mice with specific depletion of Lyve-1+ macrophages and assessed the content, types and organization of collagen in lung compartments at steady state and after chronic exposure to cigarette smoke (CS). Using this mouse model, we found that the absence of this subpopulation of tissue resident macrophage led to the deposition of type I collagen fibers around the alveoli and bronchi at steady state. Further analysis by polarized light microscopy and Sircol collagen assay revealed that the collagen fibers accumulating in the lungs depleted of Lyve-1+ macrophages were thicker and crosslinked. A decrease in MMP-9 gene expression and proteolytic activity together with an increase in Col1a1, Timp-3 and Lox expression accompanied the collagen alterations. Next, we investigated the effect of the collagen remodeling on the pathophysiology of COPD and airway function in mice lacking Lyve-1+ macrophages exposed chronically to cigarette smoke (CS), a well-established animal model of COPD. We found that deposition of collagen prior CS exposure protected these mice against destruction of alveoli (emphysema), and bronchi thickening and prevented loss of airway function. Thus, we uncover that interstitial Lyve-1+ macrophages regulate the composition, amount, and architecture of collagen network in the lungs at steady state and that such collagen remodeling functionally impacts the development of COPD. This study further supports the potential of targeting collagen as promising approaches to treat respiratory diseases.

Comparative Evaluation of Deciduous and Permanent Coronal Caries Using Polarizing Light Microscopy and Scanning Electron Microscopy.

Background: Dental caries causes mineral loss and organic damage to teeth. Understanding caries and dentin pulp reactions is crucial for effective caries management strategies. There is a lack of knowledge regarding the microscopic and ultramicroscopic changes that occur during caries destruction and reactive changes. This study used polarizing and scanning electron microscopy to compare deciduous and permanent coronal caries. Materials and Methods: The study included 30 teeth, comprising 15 primary and permanent teeth, all with coronal caries. They were also compared with 10 (5 each) noncarious primary and permanent teeth. The teeth were examined using polarizing and scanning electron microscopy to study enamel and dentin destruction, reactive dentin formation, peritubular dentin destruction, and bacterial colonization. Results: Deciduous teeth had more enamel and dentin destruction for coronal caries than permanent teeth in our study. The permanent teeth had more reactive dentin formation than primary teeth. Peritubular dentine alteration was increased in deciduous teeth, and bacterial presence on dentin was higher in permanent teeth under scanning electron microscope. Conclusion: Our findings suggest that caries destruction is more prevalent in deciduous teeth, and reactive response is more effective in permanent teeth affected by caries. These findings reflect the structural durability of the mineralized tissues and prompt reactive response of the dentin pulp complex of permanent teeth compared to deciduous teeth. Our research highlights the importance of identifying and treating decay in primary teeth at an early stage.

The Future of Structural Geology in the 21st Century – Moving from Mesoscale to Nanoscale Observations in Tectonically Deformed Rocks

ABSTRACT The importance of integrating field studies with various micro-and nano-scale structural geological investigations using petrographic microscope, scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) is highlighted in this paper. The author’s past studies dealing with SEM-EBSD and TEM investigations to decipher deformation mechanism of magnetite are taken as examples to support the robustness of investigating nanostructures in thin films excavated parallel to the kinematic reference frame. In addition, the author also shares a work flow involving collection of oriented field samples, followed by petrophysical investigations (e.g., porosity, permeability, P-wave velocity of oriented samples, etc.), 3D fabric analysis (e.g., AMS, X-ray micro-CT of oriented samples), 2D-microstructural analysis in oriented thin sections (petrography, SEM imaging including in-lens, EBSD, etc.) and finally nanostructural studies in oriented thin films using TEM (in that order). The importance of this integrated approach to evaluate structures at different scales and utilize the results for fundamental research as well as applications such as in the field of understanding fluid flow, mineralization, geothermal systems and radioactive waste management is discussed. Hence the paper provides an overview to the reader about some of the possibilities that exist today (21st century) in the field of structural geology.

Evaluation of Cartilage-Like Matrix Formation in a Nucleus Pulposus-Derived Cartilage Analog Scaffold.

The formation of fibrocartilage in microfracture (MFX) severely limits its long-term outlook. There is consensus in the scientific community that the placement of an appropriate scaffold in the MFX defect site can promote hyaline cartilage formation and improve therapeutic benefit. Accordingly, in this work, a novel natural biomaterial-the cartilage analog (CA)-which met criteria favorable for chondrogenesis, was evaluated invitro to determine its candidacy as a potential MFX scaffold. Human bone marrow stem cells (hBMSCs) were seeded onto the CA and cultured for 28 days in chondrogenic differentiation media. Sulfated glycosaminoglycan (sGAG) and hydroxyproline (HYP) contents were significantly higher than their non-seeded counterparts on both Days 14 and 28 (average sGAG on Day 28: 73.26 vs. 23.82 μg/mg dry wt. of tissue; average HYP on Day 28: 56.19 vs. 38.80 ± 2.53 μg/mg dry wt. of tissue). Histological assessments showed cellular infiltration and abundant sGAG formation for seeded CAs at both time points with new cartilage-like matrix filling up its laser-drilled channels. Polarized light microscopy of picrosirius red stained samples showed collagen fibrils aligning along the path of the laser-drilled channels. However, the seeded scaffolds were also found to have contracted by 20% by the end of the study with their average aggregate moduli significantly lower than non-seeded controls (10.52 vs. 21.74 kPa). Nevertheless, the CA was ultimately found to support the formation of a cartilage-like matrix, and therefore, merits consideration as a scaffold of interest for improving MFX.

Pulling Forces Dampen Torsional Fluctuations of Actin Filaments and Reduce Cooperative Cofilin Binding.

A variety of potential biological roles of mechanical forces have been proposed in the field of cell biology. In particular, mechanical forces alter the mechanical conditions within cells and their environment, exerting a strong effect on the reorganization of the actin cytoskeleton. Single-molecule imaging studies have provided evidence that an actin filament may act as a mechanosensor. An increase in the tension within actin filaments causes changes in their conformation and affinity to their regulatory proteins. However, our current understanding of the molecular mechanisms of the tension sensing and the affinity change of regulatory proteins is still incomplete. In this study, we employed fluorescence polarization microscopy and magnetic tweezers to directly quantify the torsional fluctuations of single actin filaments and cofilin binding to the filament under several distinct mechanical conditions. When an actin filament was severed by scratching the filament with a pipette tip, the amplitude of twisting/torsional fluctuations and the rate of cooperative cofilin binding increased. On the other hand, when a piconewton force was applied to single actin filaments by magnetic tweezers, the amplitude of twisting fluctuations and the rate of cooperative cofilin binding decreased. This may be involved in the molecular mechanism behind the mechanical force-dependent severing of actin filaments in cells.

A Case of Identity: A Technical Study of Victorian Wallpapers

ABSTRACT Public perception of arsenic in nineteenth-century Britain encompassed a variety of things: criminal poison, useful medicine, and a raw material for manufacturing an array of goods. During this era, Henry Carr tested wallpaper and fabric samples sent in by private individuals and manufacturers, as part of an early effort in gathering scientific data to inform and protect consumers against chronic arsenic poisoning. In 2022, eight wallpaper samples that Carr had tested were acquired by Winterthur Library. These samples were analyzed by polarized light microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray fluorescence, and Raman spectroscopy to identify the presence of arsenic. Of the eight wallpaper swatches, seven suggested trace-to-elevated levels of both arsenic and copper. Two swatches were confirmed as having the arsenical pigment emerald green (copper acetoarsenite) specifically. Research into these wallpaper samples furthers the legacy of knowledge gathering and sharing in order to protect everyday users by contributing to toxicology research in library and archives materials.