Competition between crystal growth and intracrystalline chain diffusion determines the lamellar thickness in semicrystalline polymers

The non-equilibrium thickness of lamellar crystals in semicrystalline polymers varies significantly between different polymer systems and depends on the crystallization temperature Tc. There is currently no consensus on the mechanism of thickness selection. Previous work has highlighted the decisive role of intracrystalline chain diffusion (ICD) in special cases, but a systematic dependence of lamellar thickness on relevant timescales such as that of ICD and stem attachment has not yet been established. Studying the morphology by small-angle X-ray scattering and the two timescales by NMR methods and polarization microscopy respectively, we here present data on poly(oxymethylene), a case with relatively slow ICD. It fills the gap between previously studied cases of absent and fast ICD, enabling us to establish a quantitative dependence of lamellar thickness on the competition between the noted timescales.

Polarization modulation with optical lock-in detection reveals universal fluorescence anisotropy of subcellular structures in live cells

The orientation of fluorophores can reveal crucial information about the structure and dynamics of their associated subcellular organelles. Despite significant progress in super-resolution, fluorescence polarization microscopy remains limited to unique samples with relatively strong polarization modulation and not applicable to the weak polarization signals in samples due to the excessive background noise. Here we apply optical lock-in detection to amplify the weak polarization modulation with super-resolution. This novel technique, termed optical lock-in detection super-resolution dipole orientation mapping (OLID-SDOM), could achieve a maximum of 100 frames per second and rapid extraction of 2D orientation, and distinguish distance up to 50 nm, making it suitable for monitoring structural dynamics concerning orientation changes in vivo. OLID-SDOM was employed to explore the universal anisotropy of a large variety of GFP-tagged subcellular organelles, including mitochondria, lysosome, Golgi, endosome, etc. We found that OUF (Orientation Uniformity Factor) of OLID-SDOM can be specific for different subcellular organelles, indicating that the anisotropy was related to the function of the organelles, and OUF can potentially be an indicator to distinguish normal and abnormal cells (even cancer cells). Furthermore, dual-color super-resolution OLID-SDOM imaging of lysosomes and actins demonstrates its potential in studying dynamic molecular interactions. The subtle anisotropy changes of expanding and shrinking dendritic spines in live neurons were observed with real-time OLID-SDOM. Revealing previously unobservable fluorescence anisotropy in various samples and indicating their underlying dynamic molecular structural changes, OLID-SDOM expands the toolkit for live cell research.

Archaeological lacquer objects from the Orgoyton burial ground

Исследованные лаковые артефакты были обнаружены при раскопках княжеского кургана хунну на могильнике Оргойтон в Забайкалье, который датируется I веком до н. э. – I веком нашей эры. Хотя захоронение было разграблено в древности, в нем были обнаружены детали колес китайской колесницы, покрытые черным лаком, а также мелкие фрагменты, возможно, осколки лаковой посуды. Технологические особенности этих разнообразных объектов были изучены путем исследования стратиграфии шлифов с помощью методов поляризационной микроскопии (ПМ) и сканирующей (растровой) электронной микроскопии в сочетании с энергодисперсионным рентгеновским микроанализом (РЭМ/ЭРМ). Состав органических материалов был изучен с помощью метода пиролитической хромато-масс-спектрометрии. В результате исследования было показано, что при создании всех предметов был использован китайский лак уруси. Поскольку лаковые деревья, сок которых служит для изготовления такого рода изделий, не произрастают в этом регионе, полученный результат дополняет имеющуюся информацию о существовании этнических контактов между Китаем и народами, проживающими в Забайкалье. После исследования археологических объектов была проведена их консервация. The studied lacquer artifacts were discovered during the excavations of the princely Hunnu burial mound at the Orgoyton burial ground in Transbaikalia, which dates back to the I century BC – I century AD and which is associated with the Asian Huns (Hunnu), in the Orgoyton burial ground on the territory of Transbaikalia. Although the burial was looted in ancient times, parts of the wheels of a Chinese chariot were found in it, covered with black lacquer, as well as small fragments, possibly fragments of lacquer ware. The technological features of these various objects were studied by studying the stratigraphy of the sections using the methods of polarization microscopy (PM) and scanning (scanning) electron microscopy in combination with energy dispersive X-ray microanalysis (SEM/ERM). The composition of organic materials was studied using pyrolytic chromatomass spectrometry. As a result of the study, it was shown that when creating all the items, Chinese urushi varnish was used. Since the lacquer trees whose sap serves for the manufacture of such products do not grow in this region, the result obtained complements the available information about the existence of ethnic contacts between China and the peoples living in Transbaikalia. After the study of archaeological sites, their conservation was carried out.

Experimental study on the performance of emulsions produced during ASP flooding

ASP (Alkaline/Surfactant/Polymer) flooding is one of the most promising techniques that has proven to have successful application in several laboratory and pilot tests. However, the formation of persistent and stable emulsions is one of the associated problems with ASP flooding. The present work investigated the effect of sodium carbonate alkaline, Alpha Olefin Sulfonate (AOS) surfactant, and GLP100 polymer on produced crude oil emulsion. The study was conducted by measuring the emulsion stability in terms of water separation and rag layer volume using a TurbiScan analyzer, the dispersed droplet size using cross-polarization microscopy, the interfacial tension using spinning drop tensiometer, and rheological properties using rheometer. The experimental results have shown that AOS presence increased the emulsion stability only when its concentration is above 100 ppm. Meanwhile, below 100 ppm, the presence of AOS promoted water separation and reduced the rag layer volume. In a less significant manner, a high concentration of sodium carbonate alkali increased the stability of the emulsion. The use of GLP100 Polymer has shown substantial ability in promoting water separation and reducing the rag layer volume to a minimal level. It is believed that the outcomes of this work will aid in developing a suitable destabilization process to enhance the oil–water separation and produced water treatment from ASP flooding in the oil production fields. Further investigations on AS, AP, SP as well as the ASP's combined effect on emulsion stability, droplet size, interfacial tension and rheological properties are highly recommended to support the decision-makers on the EOR implementations with chemical additives.

Real-time polarization microscopy of fibrillar collagen in histopathology

Over the past two decades, fibrillar collagen reorganization parameters such as the amount of collagen deposition, fiber angle and alignment have been widely explored in numerous studies. These parameters are now widely accepted as stromal biomarkers and linked to disease progression and survival time in several cancer types. Despite all these advances, there has not been a significant effort to make it possible for clinicians to explore these biomarkers without adding steps to the clinical workflow or by requiring high-cost imaging systems. In this paper, we evaluate previously described polychromatic polarization microscope (PPM) to visualize collagen fibers with an optically generated color representation of fiber orientation and alignment when inspecting the sample by a regular microscope with minor modifications. This system does not require stained slides, but is compatible with histological stains such as H&E. Consequently, it can be easily accommodated as part of regular pathology review of tissue slides, while providing clinically useful insight into stromal composition.

Study of the physical, chemical and rheological properties of oil mixtures transported through the Uzen - Atyrau - Samara pipeline

На начальных участках магистрального нефтепровода Узень - Атырау - Самара формируются партии низкозастывающих бузачинских и высокозастывающих мангышлакских нефтей. По маршруту транспортировки осуществляются дополнительные подкачки нефтей с различными физико-химическими и реологическими характеристиками, что может оказывать существенное влияние на свойства перекачиваемых нефтесмесей. Цель настоящей работы - исследование физико-химических и реологических свойств бузачинской и мангышлакской нефтесмесей на маршруте поставки Узень - Атырау, а также диапазона и причин изменений характеристик бузачинской нефти (основной в компонентном составе нефтесмесей, перекачиваемых по нефтепроводу Узень - Атырау - Самара). По результатам исследований установлено, что свойства мангышлакской нефтесмеси изменяются в незначительных пределах. Для бузачинской нефтесмеси свойственна нестабильность реологических параметров, которые могут изменяться в широком диапазоне в результате путевой подкачки на различных участках нефтепровода. Колебания реологических параметров наиболее показательных проб партий бузачинской нефтесмеси рекомендуется учитывать для решения задач повышения текучести высоковязких нефтей и оптимизации технологических режимов работы трубопроводов, по которым осуществляется перекачка таких нефтей. Методами газохроматографического анализа молекулярно-массового распределения тугоплавких парафинов и поляризационной микроскопии определена температура нагрева бузачинской и мангышлакской нефтесмесей, оптимальная для ввода депрессорной присадки. At the initial sections of the Uzen - Atyrau - Samara main oil pipeline, batches of low pour point Buzachinsky and high pour point Mangyshlak oils are formed. Additional pumping of oils with different physical, chemical and rheological characteristics is carried out along the transportation route, which can have a significant effect on the properties of the pumped oil mixtures. The purpose of this study is to examine the physical, chemical and rheological properties of Buzachi and Mangyshlak oil mixtures on the Uzen - Atyrau supply route, as well as the range and causes of changes in the characteristics of Buzachinsky oil (the main oil mixture in the blend composition pumped through the Uzen - Atyrau - Samara pipeline). According to the research results, it was found that the properties of the Mangyshlak oil mixture vary within insignificant limits. The Buzachinsky oil mixture is characterized by instability of rheological parameters, which can vary in a wide range as a result of route pumping at different pipeline sections. Fluctuations of the rheological parameters of the most indicative samples of batches of the Buzachinsky oil mixture are recommended to be taken into account in order to increase the fluidity of high-viscosity oils and optimize the process modes of operation of pipelines through which such oils are pumped. Using the methods of gas chromatographic analysis of the molecular weight distribution of high-melting-point paraffins, as well as polarization microscopy, the optimal heating temperature for the introduction of a pour point depressant into the Buzachinsky and Mangyshlak oil mixtures has been determined.

Non-Invasive Visualization of Ferroelectric Domain Structures on the Non-Polar y-Surface of KTiOPO4 via Raman Imaging

Potassium titanyl phosphate (KTP) is a nonlinear optical material with applications in high-power frequency conversion or quasi-phase matching in submicron period domain grids. A prerequisite for these applications is a precise control and understanding of the poling mechanisms to enable the fabrication of high-grade domain grids. In contrast to the widely used material lithium niobate, the domain growth in KTP is less studied, because many standard methods, such as selective etching or polarization microscopy, provides less insight or are not applicable on non-polar surfaces, respectively. In this work, we present results of confocal Raman-spectroscopy of the ferroelectric domain structure in KTP. This analytical method allows for the visualization of domain grids of the non-polar KTP y-face and therefore more insight into the domain-growth and -structure in KTP, which can be used for improved domain fabrication.

Oblique light incidence method to study topological defects in nematic layers with conical boundary conditions

A polarization microscopy method to investigate the orientational structures and boojums formed in the chiral and achiral nematic layers under conical (tilted) boundary conditions has been developed. Oblique light incidence on nematic layer is used, due to which the phase difference between the ordinary and extraordinary waves depends on the director’s azimuthal angle. The phase difference gets maximal when the director azimuthal angle of achiral nematic $$\varphi (x,y) = 0$$ φ ( x , y ) = 0 and an azimuthal angle at the center of the chiral nematic layer $$\varphi _0(x,y) = 0$$ φ 0 ( x , y ) = 0 independently of the total twist angle $$\varphi _{TOTAL}$$ φ TOTAL . It has been found that the $$m=+1$$ m = + 1 boojums with the phase $$\xi = \pm 90^\circ$$ ξ = ± 90 ∘ and $$\xi = (-90^\circ + \varphi _{TOTAL}/2)$$ ξ = ( - 90 ∘ + φ TOTAL / 2 ) are formed in achiral and chiral nematics, respectively, at the director tilt angle $$\theta _{d/2} \cong 40^\circ$$ θ d / 2 ≅ 40 ∘ at the interface. In addition, the defectless structure of chiral nematic with the periodically variable azimuthal director angle on the substrates has been studied.

FIBROSIS: POLYETIOLOGIC COMPLICATION WITH COMMON DENOMINATOR

State of the problem. The growth of fibrous connective tissue is a common complication of various pathological processes, which significantly complicates recovery and is one of the leading causes of death. Despite many years of research, the process of fibrosis development remains insufficiently studied and contains a large number of “white spots”. Fibrosis is characterized by unpredictability, propensity to grow and low level of the replacement by normal connective tissue. The structure of fibrous tissue, its differences from normal and the reasons for the formation of these differences deserve no less attention. The formation of fibrous tissue is preceded by the process of endogenous intoxication – the formation and accumulation of various abnormal metabolites. Among the latter, the leading place belongs to proteins and peptides, whose structure is disrupted and destabilized. It is known that destabilized proteins are prone to aggregation. This process, contrary to popular belief, is not chaotic, but is subject to certain laws and is aimed at minimizing of free energy. With regard of the latter circumstance a definite favorite is the formation of β-structured fibrils, which occupy almost the lowest energy level among protein conformational states. Such fibrils are characterized by insolubility, resistance to proteolysis, immunogenicity and the ability to autochthonous growth due to sorption and conformational rearrangement of soluble proteins. A classic example of such aggregation is amyloid formation, but there are good reasons to assume similar processes in the formation of other pathological tissues. The aim of the work was to verify experimentally the presence of β-structured protein aggregates in fibrous tissues, which differ in etiology. The methodical part included the selection of surgical material, its fixation in 10 % formaldehyde solution, preparation of Congo-stained red histological specimens and microscopic examination in light, polarization and fluorescence modes. Results. The presence of β-structured protein aggregates in fibrous tissues formed due to local chronic inflammation, viral infection and side effects of drugs has been proven experimentally. The identified phenomenon allows us to approach the understanding of the mechanisms of fibrosis development and to postulate a key role of regular aggregation of destabilized proteins. Conclusions. The obtained data testifies to a general and integral participation of β-structured protein aggregates in the formation of fibrous tissues of different etiologies. The presence of these deposits in fibrous tissues formed due to local chronic inflammation, viral infection and side effects of the cytostatic doxorubicin has been shown. The leading role of violation of protein homeostasis and local accumulation of structurally damaged proteins as a prerequisite for autochthonous aggregation process is discussed. The expediency of fluorescence microscopy has been shown, which significantly expands the possibilities of detecting with the help of the Congo red of nanosized β-structured protein aggregates, which are invisible due to Abbe's limitations in light and polarization microscopy. Key words: fibrosis, keloidosis, Peyronie’s disease, Covid-19, cytostatics, nanoparticles.