Polarized Light Microscopy Research Articles

BINARY CHITOSAN/QUATERNIZED CHITOSAN VIA ELECTROSPINNING. MORPHOLOGY AND ANTIMICROBIAL ACTIVITY

The paper reports about binary chitosan/quaternized chitosan nanofibers obtained by direct electrospinning of their solution, without using co-spinning polymers. Both quaternary salts, N,N,N-trimethyl chitosan chloride and N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride, were used in the electrospinning process and provided nanofibers with a mean diameter lower than 100 nm. A morphological evaluation of the nanofibers prepared with quaternized chitosan and chitosan of different molecular weights indicated that chitosan of lower molecular weight yielded fibers of higher diameter, due to the necessity to increase the concentration of the electrospinning solution in order to reach chain entanglement. Polarized light microscopy suggested that the fibers were semicrystalline in nature, in line with the ability of the macromolecular chains to align in an electrical field. Furthermore, the investigation of the antimicrobial and antifungal activities against relevant gram-positive and gram-negative bacteria, as well as yeast strains, revealed the strong effects of the nanofibers, improved by the presence of quaternary chitosan and the lower diameter of the fibers.

Influence of thermal annealing on microstructure, energetic landscape and device performance of P3HT:PCBM-based organic solar cells

Thermal annealing alters the morphology of organic donor-acceptor bulk-heterojunction thin films used in organic solar cells. Here, we studied the influence of thermal annealing on blends of amorphous regio-random (RRa) and semi-crystalline regio-regular (RR) poly (3-hexylthiophene) (P3HT) and the fullerene derivative [6,6]-phenyl-C60-butyric acid methyl ester. Since the P3HT:PCBM blend is one of the most studied in the OPV community, the existing research provides a solid foundation for us to compare and benchmark our innovative characterization techniques that have been previously under-utilized to investigate bulk heterojunction organic thin films. Here, we combine advanced novel microscopies and spectroscopies, including polarized light microscopy, photo-deflection spectroscopy, hyperspectral photoluminescence imaging, and energy resolved-electrochemical impedance spectroscopy, with structural characterization techniques, including grazing-incidence wide-angle x-ray scattering, grazing-incidence x-ray diffraction, and Raman spectroscopy, in order to reveal the impact of thermal annealing on the microstructural crystallinity and morphology of the photoactive layer in organic solar cells. Coupled transfer matrix and drift-diffusion simulations were used to study the impact of the density of states on the solar cells’ device performance parameters, namely the short-circuit current (J SC), open circuit voltage (V OC), fill factor (FF), and power conversion efficiency (PCE).

Graphitizable Pitch from Microwave Plasma Pyrolysis of Natural Gas.

An innovative approach of microwave plasma was utilized to convert natural gas into tar, from which a highly graphitizable pitch was derived using fractional distillation. The natural gas-derived pitch (NGDP) was thoroughly characterized, and the graphitizability of the carbonized NGDP was assessed using polarized light microscopy. The NGDP and, for comparison, needle coke, petroleum coke, and shot coke were subjected to graphitization heat treatment (GR) at 2500 °C. Results indicate that the graphitizability of the NGDP exceeds those of all industrial standard cokes. The GR-NGDP showed the highest degree of graphitization and crystallite size among all samples.

Experimental study on crack propagation characteristics of unconventional reservoir rocks

This study investigates the fracture behaviour of three types of specimens (shale, sandstone, and coal), which are commonly found in unconventional reservoirs, based on mode Ⅰ single-edge notch beam (SENB) test. We employ the Digital Image Correlation technique to track the strain evolution and crack propagation paths of the three types of materials and compare their fracture characteristics. The experimental results show that both the surface roughness and crack initiation angle of the coal are larger comparing with that of sandstone and shale, which demonstrates the ductile property of coal and fracturing difficulty in coal seam. Moreover, the average velocity difference of crack propagation is obvious, which is 53.76 × 103, 453, and 0.33 mm/s in shale, sandstone, and coal, respectively. The elastoplastic J-R curves, which reflects the influence of the plastic zone, are presented to analyze the energy dissipation characteristics of three types of specimens during crack propagation. It is found that the J-integral of shale and sandstone does not increase with crack propagation, but the J-integral of coal shows obvious increasing trend with crack propagation due to the effect of plasticity. In addition, microscopic analysis is conducted using a petrographic microscope and scanning electron microscope (SEM) to explain the plastic zone differences at the notch tips of shale, sandstone, and coal. This study is a preliminary and significant step of hydraulic fracturing application in unconventional reservoirs for efficient recovery of the berried natural gas.

Characterization and classification of oleogels and edible oil using vibrational spectroscopy in tandem with one-class and multiclass chemometric methods

Oleogel represents a promising healthier alternative to act as a substitute for conventional fat in various food products. Oil selection is a crucial factor in determining the technological properties and applications of oleogels due to their distinct fatty acid composition, molecular weight, and thermal properties, as well as the presence of antioxidants and oxidative stability. Hence, the relevance of monitoring oleogel properties by non-destructive, eco-friendly, portable, fast, and effective techniques is a relevant task and constitutes an advance in the evaluation of oleogels quality. Thus, the present study aims to classify oleogels rapidly and reliably, without the use of chemicals, comparing two handheld near infrared (NIR) spectrometers and one portable Raman device. Furthermore, two different multivariate methods are compared for oleogel classification according to oil type. Three types of oleogels were prepared, containing 95 % oil (sunflower, soy, olive) and 5 % beeswax as a structuring agent, melted at 90 °C. Polarized light microscopy (PLM) images were acquired, and fatty acid composition, peroxide index and free fatty acid content were determined using official methods. A total of 240 oleogel and 92 oil spectra were obtained for each instrument. After spectra pretreatment, Principal Component Analysis (PCA) was performed, and two classification methods were investigated. The Data Driven - Soft Independent Modelling of Class Analogy (DD-SIMCA) and Partial Least Squares Discriminant Analysis (PLS-DA) models demonstrated 95 % to 100 % of accuracy for the external test set. In conclusion, the use of vibrational spectroscopy using handheld and portable instruments in tandem with chemometrics showed to be an efficient alternative for classifying oils and oleogels and could be extended to other food samples. Although the classification of vegetable oils by NIR is widely used and known, this work proposes the classification of different types of oil in oleogel matrices, which has not yet been explored in the literature.

Using the traditional microscope for mineral grain orientation determination: A prototype image analysis pipeline for optic-axis mapping (POAM).

This paper reports on the development of an open-source image analysis software 'pipeline' dedicated to petrographic microscopy. Using conventional rock thin sections and images from a standard polarising microscope, the pipeline can classify minerals and subgrains into objects and obtain information about optic-axis orientation. Five metamorphic rocks were chosen to test and illustrate the method. Thin sections were imaged using reflected and cross- and plane-polarised transmitted light. Images were taken at different angles of the polariser and analyser (360° with 10° steps), both with and without the full-lambda plate. The resulting image stacks were analysed with a modular pipeline for optic-axis mapping (POAM). POAM consists of external and internal software packages that register, segment, classify, and interpret the visible light spectra using object-based image analysis (OBIAS). The mapped fields-of-view and grain orientation stereonets of interest are presented in the context of whole-slide images. Two innovations are reported. First, we used hierarchical tree region merging on blended multimodal images to classify individual grains of rock-forming minerals into objects. Second, we assembled a new optical mineralogy algorithm chain that identifies the mineral slow axis orientation. The c-axis orientation results were verified with scanning electron microscopy electron backscattered diffraction (SEM-EBSD) data. For quartz (uniaxial) in a granite mylonite the test yielded excellent correspondence of c-axis azimuth and good agreement for inclination. For orthorhombic orthopyroxene in a deformed garnet harzburgite, POAM produced acceptable results for slow axis azimuth. In addition, the method identified slight anisotropy in garnet that would not be appreciated by traditional microscopy. We propose that our method is ideally suited for two commonly performed tasks in mineralogy. First, for mineral grain classification of entire thin sections scans on blended images to provide automated modal abundance estimates and grain size distribution. Second, for prospective fields of view of interest, POAM can rapidly generate slow axis crystal orientation maps from multiangle image stacks on conventionally prepared thin sections for targeting detailed SEM-EBSD studies.

Structural parameters defining distribution of collagen fiber directions in human carotid arteries

Collagen fiber arrangement is decisive for constitutive description of anisotropic mechanical response of arterial wall. In this study, their orientation in human common carotid artery was investigated using polarized light microscopy and an automated algorithm giving more than 4·106 fiber angles per slice. In total 113 slices acquired from 18 arteries taken from 14 cadavers were used for fiber orientation in the circumferential-axial plane. All histograms were approximated with unimodal von Mises distribution to evaluate dominant direction of fibers and their concentration parameter. 10 specimens were analyzed also in circumferential-radial and axial-radial planes (2-4 slices per specimen in each plane); the portion of radially oriented fibers was found insignificant. In the circumferential-axial plane, most specimens showed a pronounced unimodal distribution with angle to circumferential direction μ = 0.7° ± 9.4° and concentration parameter b = 3.4 ± 1.9. Suitability of the unimodal fit was confirmed by high values of coefficient of determination (mean R2 = 0.97, median R2 = 0.99). Differences between media and adventitia layers were not found statistically significant. The results are directly applicable as structural parameters in the GOH constitutive model of arterial wall if the postulated two fiber families are unified into one with circumferential orientation.

Modulating fat crystallization behavior in ice cream with mono- and diglycerides: Influence on microstructure and shrinkage

Ice cream commonly experiences volume shrinkage, especially during storage and transportation with temperature fluctuations. The 3D semi-crystalline fat network supports the spatial structure of ice cream, preventing the coarsening of elements like foams and ice crystals during temperature fluctuations, ultimately reducing volume shrinkage. This study investigates the impact of fat crystallization behavior on the formation of the fat network, examining the correlation between ice cream shrinkage and fat crystallization induced by mono- and diglycerides. Techniques include differential scanning calorimetry, polarization microscopy, contact angle measurement and oscillatory thermorheometry. Shape retention is assessed through melting and freeze-thaw tests, and ice cream microstructure is observed using microscopy. Results shown mono- and diglycerides significantly impacted fat crystal wettability and emulsified fat crystallization kinetics, altering the ice cream microstructure, and contributing to heat shock-induced shrinkage. Saturated monoglyceride formed a two-dimensional crystalline layer at fat globule interface, causing fat network absence and significant shrinkage. Slightly unsaturated monoglycerides increased nucleation dimensions (n from 2.22 to 2.71), forming large fat aggregates (around 39 μm), supporting a rigid network, and reducing the shrinkage rate (from 36% to 23%). Highly unsaturated monoglycerides increased crystal growth rate (kz from 0.72 to 0.84), elevating solid fat content, and creating protrusions that damaged air bubbles, leading to a 45% shrinkage rate. Additionally, saturated emulsifiers with diglycerides reduced crystal growth rates, increased fat crystal nucleation dimensions, and hydrophobicity (kz from 0.72 to 0.63 and n from 2.22 to 3.12), forming smaller fat aggregates (around 7 μm) and minimizing shrinkage to 6%.

Effect of Laterally Substituted Methoxy Group on the Liquid Crystalline Behavior of Novel Ester Molecules

Background: The aim of this research is to study the effect of length-to-width ratio on mesomorphism to enhance the understanding of its potential applications. This will be achieved by synthesizing a unique and innovative series of identical ester molecules, including lateral methoxy groups and terminal ethyl benzoate groups. In this research, we aim to find new insights into the relationship between molecular structures and mesomorphic behaviors, which could have significant implications for the development of advanced materials with adapted properties. : The objective of the study is to investigate the mesophase behavior of new ester mesogens and determine how they are influenced by lateral methoxy groups. By identifying the underlying perspectives and relationships between these variables, we hope to better understand the unique properties and potential applications of these materials. Method: In this research work, the focus is on the synthesis of ethyl(E)-4-((3-(4-alkoxy-3- methoxyphenyl)acryloyl)oxy)benzoate, which is prepared from Steglich esterification method by using (E)-3-(4-alkoxy-3-methoxyphenyl)acrylic acid and ethyl 4- hydroxybenzoate. Synthesis processes involve precise reaction sequences designed to ensure maximum yield and purity of the final product. By providing a detailed report on the experimental process, this study contributes to the ongoing research efforts aimed at the development of innovative compounds with various applications in liquid crystals Result: A new set of liquid crystal derivatives has been synthesized and studied to investigate the effect of molecular structure on the behavior of liquid crystals, with particular attention to the group -OCH3 located laterally. This series was composed of 12 derivatives (C1-C16). Among them, the first six derivatives (C1-C6) did not have the characteristics of a liquid crystal, while the remaining derivatives (C7 and C8) had a monotropic behavior, and C10-C16 had an enantiotropic smectogenic liquid crystal behavior without exhibition of the nematic phase. The average thermal stability of the smectic property was 87.33 °C, and the mesophase range was 2 °C to 14 °C. The molecular structure was confirmed by analytical and spectral analysis. The properties of liquid crystals of this new series were compared with those of other known structurally similar homologous series. The transition temperatures were determined with an optical polarizing microscope equipped with a heating phase. Conclusion: The mesomorphic thermal and optical properties of the compounds have been validated by DSC and POM techniques. The result shows that the length of the alkyl chain has a significant influence on the mesomorphic characteristics and thermal stability of the different mesophases. Evaluation of the compounds studied indicates that the molecules are sensitive to their lateral substituent, which influences the thermal characteristics and stability of the mesophase.

Growth, Structure, and Electrical Properties of AgNbO3 Antiferroelectric Single Crystal

AgNbO3 (AN) lead-free antiferroelectric material has attracted great attention in recent years. However, little focus has been directed toward a single crystal that can provide more basic information. In this study, we successfully grew high-quality AN single crystals, using a flux method, with dimensions of 5 × 5 × 3 mm3. A systematic investigation into the crystal structure, domain structure, and electrical properties of a [001]-oriented AN single crystal was conducted. X-ray diffraction and domain structure analysis revealed an orthorhombic phase structure at room temperature. Stripe-like 90° domains aligning parallel to the [110] direction with a thickness of approximately 10–20 μm were observed using a polarized light microscope. The temperature dependence of dielectric permittivity showed M1-M2, M2-M3, and M3-O phase transitions along with increasing temperature, but the phase transition temperatures were slightly higher than those of ceramic. The AN single crystal also exhibited double polarization-electric field (P-E) hysteresis loops, which enabled good recoverable energy-storage density and efficiency comparable to ceramic. Additionally, double P-E loops were kept stable at various temperatures and frequencies, demonstrating robust stability and confirming typical antiferroelectric characteristics. Our work provides valuable insights into understanding the fundamental antiferroelectric properties of AN-based materials.

Integrated Investigations of Painting Materials in the Sasanian City of Ardaxšīr Khwarrah, near Firuzabad (Southern Iran)

Ancient Ardaxšīr Khwarrah, today known as Shahr-e Gur, situated near the modern town of Firuzabad in Fars, Iran, holds historical significance as the inaugural capital city of the Sasanian Empire. During archaeological excavations conducted in 2005 by an Iranian–German team directed by Mas‘oud Azarnoush and Dietrich Huff, a mud-brick complex was uncovered, revealing a remarkably well-preserved stretch of wall painting and a polychrome painted floor. The discovery prompted the hypothesis of a potential funerary context dating back to the Sasanian period. Both the wall painting and painted floor have suffered extensive deterioration attributed to the environmental conditions of the archaeological site, which was inscribed on the UNESCO World Heritage List in 2020. To address the urgent need for preservation and further understanding of the site’s artistic and structural elements, an emergency diagnostic project was initiated. Non-invasive investigations were carried out on the wall and floor by optical digital microscopy and portable energy-dispersive X-ray fluorescence. Additionally, representative minute samples underwent analysis through various techniques, including micro-X-ray fluorescence, polarised light microscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, micro-Raman spectroscopy, micro-Fourier Transform Infrared Spectroscopy, gas chromatography-mass spectrometry and pyrolysis coupled with gas chromatography-mass spectrometry. The palette of the floor and mural paintings were identified to contain red and yellow ochres, lead-based pigments, carbon black and bone white. The unexpected presence of Egyptian blue mixed with green earth was recognised in the green hues of the wall painting. The detection of protein material in both the wall painting and polychrome floor indicates the use of “a secco” technique, thereby shedding light on the artistic practices employed in Ardaxšīr Khwarrah.

Investigation on recrystallization of cryoprotectant solutions during warming under alternating electric fields

In the field of cryopreservation, recrystallization during rewarming is a significant factor leading to cryo-injury, causing ice crystal-induced mechanical injury to biological samples. Currently, methods, such as adding ice recrystallization inhibiting agents and increasing warming rates, have been adopted to reduce recrystallization injury. These methods also greatly increase the potential toxicity risk and engineering difficulty of cryopreservation. Accumulating research has progressively demonstrated that application of an electromagnetic field during cryopreservation can influence the preservation efficacy. However, the mechanism of action of the electric field has remained a subject of ongoing debate. We observed the recrystallization phenomenon of cryoprotectant solutions under a polarized light microscope and discovered promising experimental results. The electric field strength did not exhibit a discernible impact on the ice crystal size, while electric field frequency exerted a more significant impact. We found that at specific frequencies, the ice crystal size and growing rate were significantly affected during annealing. Compared to no electric field, an alternating electric field with a voltage of 10 V and a frequency of 5 × 104 Hz increased the recrystallization areas of a 15% (w/v) propylene glycol solution by 57%. And an alternating electric field with a voltage of 3 V and a frequency of 5 × 108 Hz decreased the recrystallization area of a 0.9% (w/v) NaCl aqueous solution by 9.9%. Different types of cryoprotectants exhibit varying responses to alternating electric fields frequency. These findings prompt us to reevaluate the role and mechanism of alternating electric fields in the cryopreservation of biological materials.

Morphological assessment of actin and desmin expression at different cold myocardial ischemia times: observational study

Background. Heart transplantation is currently the treatment of choice for patients in terminal stages of chronic heart failure. The critical shortage of donor organs and the growing need for heart transplantation necessitate the expansion of donor selection criteria, including the estimated ischemia time of the donor heart. Despite numerous studies, the issue remains regarding the safe cold ischemia time; no definite limit to the acceptable preservation time is known and no relevant pathomorphological data are available on the state of the donor heart myocardium at different time parameters. Objective. To comparatively assess the features of cardiomyocyte pathomorphology and expression of protein markers (actin and desmin) in the myocardium of a donor heart prior to the main stage of orthotopic heart transplantation. Methods. The work adopted the design of an observational clinical study, which was prospective in nature. The study used intraoperative myocardial biopsy specimens of the left atrial appendage from donors aged up to 60 years, following cold ischemia of the transplant in Bretschneider solution (Dr. Franz Köhler Chemie GmbH, Germany) lasting up to 240 minutes (Group 1, n = 10) and over 240 minutes (Group 2, n = 7). The nature of pathomorphological myocardial transformation in the left atrial appendage of the donor heart was determined at different cold ischemia times. Histological myocardial sections were stained with hematoxylin and eosin according to standard procedures. After that, they were further studied using light and polarization microscopy; the immunohistochemical method was used to analyze the expression of actin and desmin. Morphometry was performed using the ImageJ 1.48v software (USA). In the analysis of actin and desmin amount, the area of DAB(3,3′-diaminobenzidine)-positive products of the immunohistochemical reaction was estimated as a percentage of the image area. The volume density of immunohistochemically detectable actin and desmin was determined using 20 images at a magnification of 40×10. In order to study the intensity of the immune reaction, a semiquantitative method was used, which involved counting the number of cells in 25 randomly selected fields of view. The types of myocardial contracture damage were assessed via polarization microscopy. Results. Patients included in the first and second groups were comparable in terms of mean age and anthropometric indices. The mean age of patients amounted to 50 [44;59] years in Group 1 and 50 [49;50] years in Group 2, р = 0.193. The body mass index was 25 [22;27] in Group1 and 25 [21;31] in Group 2, р = 0.288. Both groups showed male predominance: 8 (80%) in Group 1 and 6 (85.7%) in Group 2, р = 0.256. The comprehensive morphological assessment of ischemic myocardial damage at different cold ischemia times revealed the uniformity and reversibility of changes in cellular structures (in both groups) that take the form of I–II class contractures, lysis changes in individual cardiomyocytes (only in Group 2), preserved immunohistochemical reactions to actin and desmin in both groups at their average intensity and the complete absence of areas showing no reaction to desmin, which gives an idea about the degree of preservation of their macromolecular structure. Conclusion. The obtained study results showed that due to having a balanced elemental composition that determines the metabolic protection of cells and their ionic balance, the Bretschneider solution effectively protects the donor heart during its transportation, with the myocardial cold ischemia lasting up to 240 min and more.

New examples of ferroelectric nematic materials showing evidence for the antiferroelectric smectic-Z phase

We present a new ferroelectric nematic material, 4-((4′-((trans)-5-ethyloxan-2-yl)-2′,3,5,6′-tetrafluoro-[1,1′-biphenyl]-4-yl)difluoromethoxy)-2,6-difluorobenzonitrile (AUUQU-2-N) and its higher homologues, the molecular structures of which include fluorinated building blocks, an oxane ring, and a terminal cyano group, all contributing to a large molecular dipole moment of about 12.5 D. We observed that AUUQU-2-N has three distinct liquid crystal phases, two of which were found to be polar phases with a spontaneous electric polarization Ps of up to 6 µC cm–2. The highest temperature phase is a common enantiotropic nematic (N) exhibiting only field-induced polarization. The lowest-temperature, monotropic phase proved to be a new example of the ferroelectric nematic phase (NF), evidenced by a single-peak polarization reversal current response, a giant imaginary dielectric permittivity on the order of 103, and the absence of any smectic layer X-ray diffraction peaks. The ordinary nematic phase N and the ferroelectric nematic phase NF are separated by an antiferroelectric liquid crystal phase which has low permittivity and a polarization reversal current exhibiting a characteristic double-peak response. In the polarizing light microscope, this antiferroelectric phase shows characteristic zig-zag defects, evidence of a layered structure. These observations suggest that this is another example of the recently discovered smectic ZA (SmZA) phase, having smectic layers with the molecular director parallel to the layer planes. The diffraction peaks from the smectic layering have not been observed to date but detailed 2D X-ray studies indicate the presence of additional short-range structures including smectic C-type correlations in all three phases—N, SmZA and NF—which may shed new light on the understanding of polar and antipolar order in these phases.

Fractal analysis of extracellular matrix for observer-independent quantification of intestinal fibrosis in Crohn’s disease

Prevention of intestinal fibrosis remains an unresolved problem in the treatment of Crohn’s disease (CD), as specific antifibrotic therapies are not yet available. Appropriate analysis of fibrosis severity is essential for assessing the therapeutic efficacy of potential antifibrotic drugs. The aim of this study was to develop an observer-independent method to quantify intestinal fibrosis in surgical specimens from patients with CD using structural analysis of the extracellular matrix (ECM). We performed fractal analysis in fibrotic and control histological sections of patients with surgery for CD (n = 28). To specifically assess the structure of the collagen matrix, polarized light microscopy was used. A score to quantify collagen fiber alignment and the color of the polarized light was established. Fractal dimension as a measure for the structural complexity correlated significantly with the histological fibrosis score whereas lacunarity as a measure for the compactness of the ECM showed a negative correlation. Polarized light microscopy to visualize the collagen network underlined the structural changes in the ECM network in advanced fibrosis. In conclusion, observer-independent quantification of the structural complexity of the ECM by fractal analysis is a suitable method to quantify the degree of intestinal fibrosis in histological samples from patients with CD.

Effects of microwave radiation on the physicochemical properties, structure, and digestibility of the synthesized different crystal forms of malic acid starch ester

The effects of microwave combined with L-malic acid treatment on the degree of substitution (DS), structure, physicochemical properties, and digestibility of sweet potato starch (A-type), potato starch (B-type), and pea starch (C-type) were evaluated. The order of DS obtained was: DSM-POS > DSM-SPS > DSM-PES. Fourier transform-infrared spectroscopy (FT-IR) showed that the obtained modified starch produced a new absorption band at 1735 cm−1. Scanning electron microscopy (SEM) and polarized light microscopy indicated that different types of native starches exhibited different granular morphologies and appeared to have different degrees of damage, but still had polarized crosses after modification. Sweet potato starch had the smallest particle size, while potato starch had the largest. X-ray diffractometry (XRD) showed that the modified starches still retained the same crystal structure as the native starches, but the relative crystallinity decreased. The apparent viscosity and swelling power of modified starches dropped, but their water/oil holding capacity, amylose content, and resistant starch content all increased. The results demonstrate that the degree of influence on the structure, physicochemical properties, and digestibility of different starches varies under the same modification conditions.

Unusual Structural Insights Revealed by Rheo-SAXS Studies of Nonaqueous Crystalline Gels.

Glycerol is a nonaqueous polar solvent and is of interest in many industrial areas due to its beneficial properties, such as green production and biocompatibility. Our previous works have shown the presence of a fibrillar phase on the microscale that consists of lamellar sodium dodecyl sulfate (SDS) crystals containing interstitial glycerol on the nanoscale. The phase is gel-like at room temperature and demonstrates shear-thinning behavior upon application of a shear. Initially, small-angle X-ray scattering coupled with rheology (rheo-SAXS) measurements were performed to elucidate the structural transition of the gel phase under an applied shear, but it became clear that the aging process of the gel has a profound impact on both the gel nanostructure and also the mechanical properties. For younger gels, both the dissolution of SDS crystallites and the alignment of the fibrillar phase were seen. However, in the aged gels, an unexpected foam was formed at shear rates > 700 s-1. The microscopic structure of the foam phase was imaged using polarizing light microscopy and brightfield and darkfield optical microscopy. The nanostructure of the foam phase was investigated using rheo-SAXS. The foam phase was shown to be stabilized by the presence of SDS crystallites at the air-liquid interface, and the stability of the foam is high with foam persisting even t = 3 months after formation. These results highlight the importance of investigating green nonaqueous media and the gel aging process, both of which are interesting not only on a fundamental level but also for a range of industrial applications, from personal care products and cosmetics to food science.

Third-Generation Solid Dispersion Through Lyophilization Enhanced Oral Bioavailability of Resveratrol.

Resveratrol (RES) is a biopharmaceutical classification system (BCS) class II compound with low solubility and high permeability. Several strategies have been explored to overcome the low bioavailability of RES, making the formation of solid dispersions (SDs) one of the most promising. This study aimed at the development of a RES third-generation SD prepared by lyophilization as a strategy to improve RES solubility, dissolution, and oral bioavailability. Eudragit E PO was selected as the hydrophilic carrier in a 1:2 (RES:carrier) ratio, and Gelucire 44/14 as the surfactant, at 16% (w/w) of RES. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), polarized light microscopy (PLM), X-ray powder diffraction (XRPD), and particle size distribution (Morphologi 4 Malvern) were used for solid-state characterization and to confirm the conversion of RES to the amorphous state in the SD. Third-generation SD presented an 8-, 12-, and 8-fold increase of RES solubilized compared to pure RES at pH 1.2, 4.5, and 6.8, respectively, and a 10-fold increase compared to the physical mixture (PM), at pH 6.8, after 24 h. In the gastric environment, the dissolution rate of third-generation SD and PM was similar, and 2-fold higher than pure RES after 30 min, while at pH 6.8, third-generation SD presented approximately a 5-fold increase in comparison to pure RES and PM. Third-generation SD presented higher in vitro intestinal permeability compared to its PM and second-generation SD (without Gelucire 44/14). A 2.4 and 1.7-fold increase of RES permeated, respectively in Caco-2 and Caco-2/HT2-MTX models, was obtained with third-generation SD compared to PM, after 3 h. Third-generation SD allowed a 3-fold increase of RES bioavailability compared to second-generation SD, after oral administration of 200 mg/kg of RES to Wistar rats. Enhanced RES oral bioavailability was obtained not only by solubility and dissolution improvement, but also by the interference of Gelucire 44/14, with RES metabolism, and inhibition of P-gp-mediated efflux. The presence of excipients like Gelucire 44/14 in the SD allows for greater bioavailability of orally administered RES, making it easier to obtain some of the physiological benefits demonstrated by this molecule.

Colourants on the Persian architectural decorations from the 11th to the 15th century

AbstractOver 200 samples from colourants appeared in 50 monuments in Iran dated back to the 11th century up to the 15th century were identified using micro‐X‐ray fluorescence (μ‐XRF), micro‐Raman spectroscopy (μ‐Raman), polarized light microscopy (PLM), and scanning electron microscopy–energy dispersive X‐ray spectrometry (SEM‐EDS). Whereas red ochre, red lead, vermilion, and an organic red dye were identified as red colourants, ultramarine blue, azurite, and indigo were the blue colourants occurred in the wall decorations. In addition, atacamite was the only green pigment identified on the wall paintings and stucco decorations, and carbon black was identified as black pigment. We also show that gold leaf and tin foil have been used in gilding decorations. Furthermore, we were able to discern yellow ochre together with orpiment, natrojarosite, and crocoite in a number of architectural decorations. Moreover, we show that huntite and gypsum are used as white preparation layer of the wall decorations in Iran. Periods of emergence of particular pigments have been discussed and regional preferences in the use of certain pigments are argued. An extensive discussion is provided to compare the colourant appeared on wall decoration with those appeared on illuminated manuscripts in the Persianate world.

Pickering Emulsions of Thermotropic Liquid Crystals Stabilized by Amphiphilic Gold Nanoparticles.

We report emulsions of thermotropic liquid crystals (LCs) in water that are stabilized using amphiphilic gold nanoparticles (AuNPs) and retain their ability to respond to aqueous analytes for extended periods (e.g., up to 1 year after preparation). These LC emulsions exhibit exceptional colloidal stability that results from the adsorption of AuNPs that are functionalized with thiol-terminated poly(ethylene glycol) (PEG-thiol) and hexadecanethiol (C16-thiol) to LC droplet interfaces. These stabilized LC emulsions respond to the presence of model anionic (SDS), cationic (C12TAB), and nonionic (C12E4) surfactants in the surrounding aqueous media, as evidenced by ordering transitions in the LC droplets that can be readily observed using polarized light microscopy. Our results reveal significant differences in the sensitivity of the stabilized LC droplets toward each of these analytes. In particular, these stabilized droplets can detect the cationic C12TAB at concentrations that are lower than those required for bare LC droplets under similar experimental conditions (0.5 and 2 mM, respectively). These results demonstrate an enhanced sensitivity of the LC toward C12TAB when the PEG/C16-thiol-coated AuNPs are adsorbed at LC droplet interfaces. In contrast, the concentrations of SDS required to observe optical transformations in the stabilized LC droplets are higher than those required for the bare LC droplets, suggesting that the presence of the PEG/C16-thiol AuNPs reduces the sensitivity of the LC toward this analyte. When combined, our results show that this Pickering stabilization approach using amphiphilic AuNPs as stabilizing agents for LC-in-water emulsions provides a promising platform for developing LC droplet-based optical sensors with long-term colloidal stability as well as opportunities to tune the sensitivity and selectivity of the response to target aqueous analytes.