Membrane Boundary Research Articles

Integrated Pumped Hydro Reverse Osmosis System optimization featuring surrogate model development in Reverse Osmosis modeling

The pressure head generated by the upper reservoir of a pumped hydro energy storage system can be sufficient for creating the pressure gradient required for a reverse osmosis desalination plant. Combined with the fact that many drought-stricken coastal areas have nearby mountains at the necessary elevation for these upper (mountaintop) reservoirs, a symbiotic relationship can be ascertained through the co-location of a pumped storage hydropower (PSH) system with a reverse osmosis (RO) desalination system. Merging PSH and RO into one Integrated Pumped Hydro Reverse Osmosis System (IPHROS) instead of implementing each individually could result in a number of benefits, including reduced capital investment, lower maintenance costs, and a natural mechanism for diluting the highly saline brine discharge generated from the RO process. This paper extends the work of Slocum et al. in 2016, who first introduced the concept of IPHROS, by optimizing the amount of seawater sent to and diverted from the upper reservoir for maximal energy recapture and freshwater production, respectively, while also seeking to maximize the RO system recovery ratio. For this multiobjective optimization, a new reverse osmosis model is created that utilizes a blend of empirical and fundamental equations based on the solution–diffusion model of membrane transport and boundary layer effects that naturally occur along reverse osmosis membranes. Additionally, surrogate models are developed to predict the permeate flowrate and fractional salt rejection rate for a Seamaxx™-440 RO element. Optimizing the presented IPHROS model reveals a 16% decrease in the break even time for IPHROS compared to PSH and RO being implemented individually, and that at the best design with regards to the energy, freshwater, and RO system recovery objectives, 79.5 million kWh of energy and 5.79 million cubic meters of fresh water can be delivered to a population, significant amounts for a population seeking to transition to a renewable energy-based grid and alleviate dire freshwater conditions. Enhanced modeling and optimization, as was initiated in this paper, will eventually aid in IPHROS’ large-scale adoption into energy and freshwater infrastructures.

Cardiolipin prolongs the lifetimes of respiratory proteins in Drosophila flight muscle

Respiratory complexes and cardiolipins have exceptionally long lifetimes. The fact that they co-localize in mitochondrial cristae raises the questions of whether their longevities have a common cause and whether the longevity of OXPHOS proteins is dependent on cardiolipin. To address these questions, we developed a method to measure side-by-side the half-lives of proteins and lipids in wildtype Drosophila and cardiolipin deficient mutants. We fed adult flies with stable isotope-labeled precursors (13C615N2-lysine or 13C6-glucose) and determined the relative abundance of heavy isotopomers in protein and lipid species by mass spectrometry. To minimize confounding effects of tissue regeneration, we restricted our analysis to the thorax, the bulk of which consists of post-mitotic flight muscles. Analysis of 680 protein and 45 lipid species showed that the subunits of respiratory complexes I-V and the carriers for phosphate and ADP/ATP were among the longest-lived proteins (average half-life of 48±16 days) while the molecular species of cardiolipin were the longest-lived lipids (average half-life of 27±6 days). The remarkable longevity of these crista residents was not shared by all mitochondrial proteins, especially not by those residing in the matrix and the inner boundary membrane. Ablation of cardiolipin synthase, which causes replacement of cardiolipin by phosphatidylglycerol, and ablation of tafazzin, which causes partial replacement of cardiolipin by monolyso-cardiolipin, decreased the lifetimes of the respiratory complexes. Ablation of tafazzin also decreased the lifetimes of the remaining cardiolipin species. These data suggest that an important function of cardiolipin in mitochondria is to protect respiratory complexes from degradation.

Three membrane fusion pore families determine the pathway to pore dilation

During exocytosis secretory vesicles fuse with a target membrane and release neurotransmitters, hormones, or other bioactive molecules through a membrane fusion pore. The initially small pore may subsequently dilate for full contents release, as commonly observed in amperometric traces. The size, shape, and evolution of the pore is critical to the course of contents release, but exact fusion pore solutions accounting for membrane tension and bending energy constraints have not been available. Here, we obtained exact solutions for fusion pores between two membranes. We find three families: a narrow pore, a wide pore, and an intermediate tether-like pore. For high tensions these are close to the catenoidal and tether solutions recently reported for freely hinged membrane boundaries. We suggest membrane fusion initially generates a stable narrow pore, and the dilation pathway is a transition to the stable wide pore family. The unstable intermediate pore is the transition state that sets the energy barrier for this dilation pathway. Pore dilation is mechanosensitive, as the energy barrier is lowered by increased membrane tension. Finally, we study fusion pores in nanodiscs, powerful systems for the study of individual pores. We show that nanodiscs stabilize fusion pores by locking them into the narrow pore family.

Triaxial Shear Analysis Using Discrete Element Methods for Sandy Soil with an Improved Flexible Membrane Boundary

Exploring strain localization has substantial potential to significantly impact the disaster resilience and mitigation capabilities of infrastructure, thus influencing project sustainability. Consequently, the field of sustainable geotechnical engineering is progressively directing attention toward studying soil strain localization. This research focuses on triaxial testing to deepen our understanding of this phenomenon by applying discrete element methods, thereby fostering the advancement of sustainable geotechnical engineering practices. While rigid-wall-based discrete element triaxial tests have been extensively studied, using flexible boundaries in these tests has received limited attention. This study introduces a three-stage method to enhance stress application in flexible membranes by applying confining pressure. A comparison of triaxial tests was conducted at both macroscopic and microscopic scales, utilizing flexible and rigid boundaries. Moreover, numerical simulations were performed on flexible membrane samples with various particle sizes to identify appropriate dimensions for flexible boundaries. Our results demonstrate that the improved flexible membrane provides more accurate representations of macroscopic and microscopic sample variations than rigid walls. Keeping the particle sizes for flexible membranes within the range of 0.2 to 0.8 times the characteristic particle size (r) is essential for striking a balance between simulation accuracy and computational efficiency. These findings enhance the accuracy of triaxial compression test simulations and offer a valuable foundation for studying strain localization in soils. Understanding these phenomena is essential for various geotechnical engineering applications, such as foundation design and slope stability analysis. Furthermore, these findings form a pivotal foundation for resource optimization and enhancing the reliability of engineered structures, thereby driving the advancement of sustainable geotechnical engineering practices.

Invadopodia Formation in Cancer Cell: The Mathematical and Computational Modelling Based on Free Boundary Problem

We present a mathematical model of an individual cell to expand the simulation of invadopodia formation to a three-dimensional (3D) domain for a more realistic complexity. Simulating invadopodia replication in order for it to be biologically relevant is important since it helps us to understand cancer invasion and metastasis better as well as giving some insight into investigating ways to stop the spread of this fatal disease. Invadopodia formation is formulated using the Stefan problem approach, where the free boundary is characterised by the Stefan free boundary condition, in which the boundary membrane is not known in advance. Level set method is proposed to indicate the behaviour of the cell interface and the motion of the plasma membrane. An enthalpy method (phase-transition problem) is used to describe the cell membrane diffusion. In addition to this, we were able to improve the simulation outcome, giving it a more realistic complexity by using a different simulation technique and domain as well as a different data set. Singularities and instabilities were eliminated. The results that were achieved have the potential to be helpful for novel approaches or to be extended to other methods in the development of a more accurate numerical simulation.

Kinetic control of shape deformations and membrane phase separation inside giant vesicles.

A variety of cellular processes use liquid-liquid phase separation (LLPS) to create functional levels of organization, but the kinetic pathways by which it proceeds remain incompletely understood. Here in real time, we monitor the dynamics of LLPS of mixtures of segregatively phase-separating polymers inside all-synthetic, giant unilamellar vesicles. After dynamically triggering phase separation, we find that the ensuing relaxation-en route to the new equilibrium-is non-trivially modulated by a dynamic interplay between the coarsening of the evolving droplet phase and the interactive membrane boundary. The membrane boundary is preferentially wetted by one of the incipient phases, dynamically arresting the progression of coarsening and deforming the membrane. When the vesicles are composed of phase-separating mixtures of common lipids, LLPS within the vesicular interior becomes coupled to the membrane's compositional degrees of freedom, producing microphase-separated membrane textures. This coupling of bulk and surface phase-separation processes suggests a physical principle by which LLPS inside living cells might be dynamically regulated and communicated to the cellular boundaries.

Measuring the Tension Stress in Fixed Boundary Membrane Structure by Vibration Method

In this paper, a linear relationship between the frequency of membrane structures and their inner tension stress has been studied. The analytical relationships between the vibration frequency and the tension stress were obtained, and the results were verified by experiment and finite element simulations.

Surgical Treatment of Primary Penetrating Macular Retinal Tears Using an “Effective” Fragment of the Internal Limiting Membrane

The purpose: to develop a technology for the surgical treatment of macular retinal tears using an “effective” fragment of the ILM with an optimal shape, size, and localization, and evaluate its anatomical and functional efficiency.Methods. There were 10 patients (8 women, 2 men) with primary through macular holes of large diameter (more than 400 microns) under observation. The age were from 55 to 64 years old. The duration of macular tear existence ranged from 4 to 11 months. Patients underwent standard research methods, SOCT and microperimetry. To retain the point of visual fixation and eliminate the risk of retinal trauma, all patients underwent surgical treatment of macular tear using the developed method for the surgical treatment of macular retinal tears using an “effective” ILM fragment of the required shape, size and localization. Before the operation, individual parameters for each patient and zones of localization of the “effective” ILM fragment were calculated, which consisted of two parts: the upper inverted fragment and the intact foveolar fragment of the inner limiting membrane. The follow-up period was 1, 3, 6 months and 1 year after the operation.Results. Surgical treatment of MR in all patients was carried out completely without complications. In all cases, it was possible to preserve the zone of the foveolar intact fragment of the ILM and form the upper inverted fragment of the ILM, which directly covers the macular hole. Improvement of the anatomical state of the retina in the foveal area was achieved according to SOCT data. After 1 month, all patients had a “defect” (hyporeflective area) in the ellipsoid zone of photoreceptors with a width of 112 to 357 μm. The outer boundary membrane was clearly visible and had a linear profile. A complete resorption of edema along the edges of the tear happened. An intact foveolar fragment of the ILM was visualized on the surface of the retina, blocking the macular hole. After 3 months, in 3 patients, the defect of the outer layers of the retina completely disappeared. After 3, 6 and 12 months, the state of the retina of these patients was unchanged. All patients showed improvement in functional outcomes after surgical treatment. There was an increase in BCVA at all terms.Conclusion. The developed technology of surgical treatment using an “effective” ILM fragment is modern and safe in the treatment of penetrating primary macular retinal tears, and reduces the risk of intra- and postoperative complications.

MICU1 deficiency alters mitochondrial morphology and cytochrome C release

The mitochondrial inner boundary membrane harbors a protein called MICU1, which is sensitive to Ca2+ and binds to the MICOS components Mic60 and CHCHD2. Changes in the mitochondrial cristae junction structure and organization in MICU1−/− cells lead to increased cytochrome c release, membrane potential rearrangement, and changes in mitochondrial Ca2+ uptake dynamics. These findings shed new light on the multifaceted role of MICU1, highlighting its involvement not only as an interaction partner and regulator of the MCU complex but also as a crucial determinant of mitochondrial ultrastructure and, thus, an essential player in processes initiating apoptosis.

Effects of an easy-to-implement water management strategy on performance and degradation of polymer electrolyte fuel cells

Intermittent switching between wet and dry reactant gases during operation in a polymer electrolyte fuel cell (PEFC) can improve performance stability, alleviating the effects of flooding by controlling the water content within the system. However, lifetime durability may be affected due to membrane electrode assembly (MEA) boundary delamination and membrane damage. Two relative humidity (RH) control strategies were investigated, using electrochemical performance and MEA degradation as critical indicators. It was found that intermittent switching between wet and dry gases does not accelerate fuel cell degradation if the duration of the dry gas period is set reasonably (dry gases stops before the voltage reaches the apex of the hump). Additionally, current and temperature distribution mapping was utilised to capture the dynamic response between these transitional stages. The switching of dry gases first makes the current density distribution homogeneous, and the maximum current density is reduced subsequently. Then, the current density near the inlet keeps decreasing. Intermittent switching between wet and dry reactant gases is easy to implement and overcomes limitations in mass transfer at medium and high current densities.

Monitoring Lesion Area Progression in Stargardt Disease: A Comparison of En Face Optical Coherence Tomography and Fundus Autofluorescence.

To compare longitudinal changes in en face spectral domain-optical coherence tomography (SD-OCT) measurements of ellipsoid zone (EZ) and retinal pigment epithelium (RPE) loss to changes in the hypoautofluorescent and hyperautofluorescent (AF) areas detected with short-wavelength (SW)-AF in ABCA4-associated retinopathy. SD-OCT volume scans were obtained from 20 patients (20 eyes) over 2.6 ± 1.2 years (range 1-5 years). The EZ, and RPE/Bruch's membrane boundaries were segmented, and en face slab images generated. SubRPE and EZ slab images were used to measure areas of atrophic RPE and EZ loss. These were compared to longitudinal measurements of the hypo- and abnormal AF (hypoAF and surrounding hyperAF) areas. At baseline, the en face area of EZ loss was significantly larger than the subRPE atrophic area, and the abnormal AF area was significantly larger than the hypoAF area. The median rate of EZ loss was significantly greater than the rate of increase in the subRPE atrophic area (1.2 mm2/yr compared to 0.5 mm2/yr). The median rate of increase in the abnormal AF area was significantly greater than the increase in the hypoAF area (1.6 mm2/yr compared to 0.6 mm2/yr). En face SD-OCT can be used to quantify changes in RPE atrophy and photoreceptor integrity. It can be a complementary or alternative technique to SW-AF with the advantage of monitoring EZ loss. The SW-AF results emphasize the importance of measuring changes in the hypo- and abnormal AF areas. The findings are relevant to the selection of outcome measures for monitoring ABCA4-associated retinopathy.

Mitochondrial Cristae Morphology Reflecting Metabolism, Superoxide Formation, Redox Homeostasis, and Pathology.

Significance: Mitochondrial (mt) reticulum network in the cell possesses amazing ultramorphology of parallel lamellar cristae, formed by the invaginated inner mitochondrial membrane. Its non-invaginated part, the inner boundary membrane (IBM) forms a cylindrical sandwich with the outer mitochondrial membrane (OMM). Crista membranes (CMs) meet IBM at crista junctions (CJs) of mt cristae organizing system (MICOS) complexes connected to OMM sorting and assembly machinery (SAM). Cristae dimensions, shape, and CJs have characteristic patterns for different metabolic regimes, physiological and pathological situations. Recent Advances: Cristae-shaping proteins were characterized, namely rows of ATP-synthase dimers forming the crista lamella edges, MICOS subunits, optic atrophy 1 (OPA1) isoforms and mitochondrial genome maintenance 1 (MGM1) filaments, prohibitins, and others. Detailed cristae ultramorphology changes were imaged by focused-ion beam/scanning electron microscopy. Dynamics of crista lamellae and mobile CJs were demonstrated by nanoscopy in living cells. With tBID-induced apoptosis a single entirely fused cristae reticulum was observed in a mitochondrial spheroid. Critical Issues: The mobility and composition of MICOS, OPA1, and ATP-synthase dimeric rows regulated by post-translational modifications might be exclusively responsible for cristae morphology changes, but ion fluxes across CM and resulting osmotic forces might be also involved. Inevitably, cristae ultramorphology should reflect also mitochondrial redox homeostasis, but details are unknown. Disordered cristae typically reflect higher superoxide formation. Future Directions: To link redox homeostasis to cristae ultramorphology and define markers, recent progress will help in uncovering mechanisms involved in proton-coupled electron transfer via the respiratory chain and in regulation of cristae architecture, leading to structural determination of superoxide formation sites and cristae ultramorphology changes in diseases.

Abstract 2250: Immuno-oncology study to profile the tumor microenvironment in multiple human cancers using high-plex imaging mass cytometry

Abstract Immune profiling of tumor tissues has become a key tool in understanding the complexity of the tumor microenvironment (TME), for predictive biomarker discovery, and in cancer treatment. The presence of tumor-infiltrating lymphocytes has been associated with benefit from therapy. Furthermore, the TME also contains immunosuppressive elements that can impede immune response. Imaging Mass Cytometry™ (IMC™) enables detailed assessment of cell phenotype and function using 40-plus markers simultaneously at subcellular resolution on a single slide without spectral overlap or background autofluorescence. High-plex IMC has enabled us to evaluate the TME in different cancer histologies including in highly autofluorescent tissue types like lung, hepatocellular carcinoma, and skin melanoma. The Maxpar® Human Immuno-Oncology IMC Panel Kit (201508) was customized using antibodies from the Standard BioTools™ catalog to create panels for tissue-based immuno-oncology research. Data acquisition was performed using a Hyperion™ Imaging System. To facilitate cell segmentation, an IMC Cell Segmentation Kit (TIS-00001) was applied to enhance cell membrane boundaries. We applied a pixel classification approach and CellProfiler™ for single-cell segmentation. We used histoCAT™ for single-cell analysis to visualize protein expression in various cancer types via PhenoGraph clustering and t-SNE maps. Our panels were applied to normal and cancer human tissue microarrays (TMAs) to phenotype and analyze cell populations in these tissues. We provide detailed analysis of the TME by classifying activation state of immune cell populations, epithelial-to-mesenchymal transition (EMT) progression, and composition of the extracellular matrix. In-depth single-cell analysis quantitatively evaluated the cellular makeup and immune cell component in the TME of cancer tissues and identified major tumor, immune, and stromal cell phenotypes. This work demonstrates the capability of IMC for quantitative and spatial identification of multiple immune parameters in the TME on a single slide of cancer patient samples (e.g. tumor microarray). For Research Use Only. Not for use in diagnostic procedures. Citation Format: Thomas D. Pfister, Liang Lim, Shaida Ouladan, Nick Zabinyakov, Qanber Raza, Christina Loh. Immuno-oncology study to profile the tumor microenvironment in multiple human cancers using high-plex imaging mass cytometry [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2250.

Изменения микроперимерических параметров сетчатки при закрытии макулярного разрыва с сохранением внутренней пограничной мембраны

Purpose. To propose the technique of surgery and to conduct a comparative analysis of the microperimetric parameters of the retina for macular hole (MR) using various techniques. Material and methods. The results of surgical treatment of 90 patients (90 eyes) with a diagnosis of macular hole were analyzed. The patients were divided into two groups: group 1 – patients who underwent ILM peeling; group 2 – patients whose macular hole was closed with the preservation of ILM in the foveolar zone and nasal part. All patients underwent a standard ophthalmological examination and an OCT study. Results. On the 30th day after surgery, there was a statistically significant excess of microperimetric parameters from the nasal part of the macular zone: the upper nasal and lower nasal quadrants, where peeling was not performed (p = 0.032) and (p = 0.034), respectively. Conclusion. When conducting a membrane-preserving peeling technique, the risks of intraoperative damage to the retinal Сlayers are reduced. A higher functional result was obtained in comparison with the group where the standard technique was used. Keywords: microperimetry, macular rupture, peeling of the inner boundary membrane

Wayfinding artificial intelligence to detect clinically meaningful spots of retinal diseases: Artificial intelligence to help retina specialists in real world practice.

To aim of this study is to develop an artificial intelligence (AI) that aids in the thought process by providing retinal clinicians with clinically meaningful or abnormal findings rather than just a final diagnosis, i.e., a "wayfinding AI." Spectral domain optical coherence tomography B-scan images were classified into 189 normal and 111 diseased eyes. These were automatically segmented using a deep-learning based boundary-layer detection model. During segmentation, the AI model calculates the probability of the boundary surface of the layer for each A-scan. If this probability distribution is not biased toward a single point, layer detection is defined as ambiguous. This ambiguity was calculated using entropy, and a value referred to as the ambiguity index was calculated for each OCT image. The ability of the ambiguity index to classify normal and diseased images and the presence or absence of abnormalities in each layer of the retina were evaluated based on the area under the curve (AUC). A heatmap, i.e., an ambiguity-map, of each layer, that changes the color according to the ambiguity index value, was also created. The ambiguity index of the overall retina of the normal and disease-affected images (mean ± SD) were 1.76 ± 0.10 and 2.06 ± 0.22, respectively, with a significant difference (p < 0.05). The AUC used to distinguish normal and disease-affected images using the ambiguity index was 0.93, and was 0.588 for the internal limiting membrane boundary, 0.902 for the nerve fiber layer/ganglion cell layer boundary, 0.920 for the inner plexiform layer/inner nuclear layer boundary, 0.882 for the outer plexiform layer/outer nuclear layer boundary, 0.926 for the ellipsoid zone line, and 0.866 for the retinal pigment epithelium/Bruch's membrane boundary. Three representative cases reveal the usefulness of an ambiguity map. The present AI algorithm can pinpoint abnormal retinal lesions in OCT images, and its localization is known at a glance when using an ambiguity map. This will help diagnose the processes of clinicians as a wayfinding tool.

Structural and functional regulation of Chlamydomonas lysosome-related organelles during environmental changes.

Lysosome-related organelles (LROs) are a class of heterogeneous organelles conserved in eukaryotes that primarily play a role in storage and secretion. An important function of LROs is to mediate metal homeostasis. Chlamydomonas reinhardtii is a model organism for studying metal ion metabolism; however, structural and functional analyses of LROs in C. reinhardtii are insufficient. Here, we optimized a method for purifying these organelles from 2 populations of cells: stationary phase or overloaded with iron. The morphology, elemental content, and lysosomal activities differed between the 2 preparations, even though both have phosphorus and metal ion storage functions. LROs in stationary phase cells had multiple non-membrane-bound polyphosphate granules to store phosphorus. Those in iron-overloaded cells were similar to acidocalcisomes (ACs), which have a boundary membrane and contain 1 or 2 large polyphosphate granules to store more phosphorus. We established a method for quantifying the capacity of LROs to sequester individual trace metals. Based on a comparative proteomic analysis of these 2 types of LROs, we present a comprehensive AC proteome and identified 113 putative AC proteins. The methods and protein inventories provide a framework for studying the biogenesis and modification of LROs and the mechanisms by which they participate in regulating metal ion metabolism.

Graph partitioning algorithms with biological connectivity decisions for neuron reconstruction in electron microscope volumes

Neuron reconstruction algorithms used in electron microscope volumes have received increasing attention in recent years. Most current methods are highly reliant on neuron membrane boundary evidence without considering biological plausibility. In this investigation, we present a novel neuron reconstruction framework via the fusion of a global optimization goal and biologically inspired priors. We encode the 3D instances of synapses and mitochondria as two types of constraints to allow for the direct inclusion of non-local connectivity information in the neuron segmentation. Moreover, a flexible decision procedure is designed to retain high-confidence priors to deal with the possible influence of the upstream ultrastructure error. We construct the constrained graph partitioning model and adapt two greedy algorithms with the polynomial time complexity to solve the proposed model. We perform comparative studies on several public datasets and demonstrate that the decision of ultrastructural connectivity constraints contributes to significant improvements over existing hierarchical agglomeration algorithms. The ablation studies of ultrastructures from different recognition accuracy suggest the generality and applicability of the proposed method.

ULTRASTRUCTURAL ORGANIZATION OF THE RETINA LAYERS OF THE RAT IN NORM

The use of experimental animals with the aim of studying the dynamics of morphological changes requires deep knowledge of the initial indicators of the structure of the studied object in norm. In scientifi c medical literature, great importance belonges to the study of the retina in norm and the processes of changes in its structure under the infl uence of various nosologies. Considering the complexity of the retina structure and its role in the receiving information from the surrounding environment, it is important to understand the peculiarities of its layered organization in order to create a morphological basis for further comparing the experimental material and comparing it with the initial indicators of the norm with the results obtained at diff erent periods of the experimentally reproduced pathology. The aim of the study was to fi nd out the peculiarities of the layered structure of the cellular elements of the retina on the ultrastructural level in norm. Material and methods. The research material was 10 sexually mature, purebred male rats, weighing 160 g, aged 4.5 months. Before taking the material of the experimental area, the animal was removed from the experiment with the help of diethyl ether. Rat eyeballs were used as material for ultrastructural research. Ultrastructural samples were prepared according to the generally accepted method. As a result of our study of the retina of an intact group of animals, its layers preserved a clear stratifi cation architecture. The layer of the pigment epithelium was localized on Bruch’s membrane, choroidal vessels contained single erythrocytes and blood plasma. The nuclei of the pigment epithelium were preserved, the basal folds of the plasmolemma were clearly contoured. Small phagosomes were located in the cytoplasm of the pigment epithelium in one or two rows. The apical microvilli of the pigment epithelium were preserved, the interphotoreceptor space was hermetic. The membrane discs of the outer segments of the rods were clearly contoured. The cytoplasmic isthmus between the outer and inner segments of photoreceptors was intact. The outer boundary membrane was intensively osmophilic, preserved. Photoreceptor nuclei in the outer nuclear layer, clearly contoured. The synaptic zone of the outer reticular layer contained synaptic membranes and synaptic vesicles. The nuclei of horizontal and bipolar cells, the nuclei of Mьller cells and the nuclei of amacrine cells were located in the inner nuclear layer. The lumens of the vessels of the inner reticular layer were not dilated, they contained single erythrocytes. Nuclei and perikaryons of ganglion cells were arranged in one or two rows. Cytoplasmic structures of large gangloinary cells were preserved.

Effect of flexible membrane in large-scale triaxial test DEM simulations

The use of flexible membrane boundaries in simulations of ballast triaxial tests with the discrete element method (DEM) has become increasingly popular, due to the benefits of more uniform confining pressure and realistic specimen deformation. However, it is not well understood whether the simulated flexible membranes may lead to overstated results due to extra confinement of the specimen. To investigate this, a series of three-dimensional (3D) discrete element simulations were performed using different flexible membrane configurations and parameters. The results showed that the flexible membrane has an effect on the stress-strain response of the specimen once axial strain exceeds 1%, and that a higher stiffness and larger element size of the membrane leads to greater extra confinement during shearing. A correlation model was developed to predict the extra confinement of the flexible membrane, which was validated to reasonably predict the restriction on triaxial test simulations.

Study on the synergistic heat transfer of double boundary layers in the jacketed vacuum membrane distillation process

During the process of membrane distillation (MD) heat recovery, due to the adverse effects of the heat exchange boundary layer and membrane surface boundary layer, the latent heat is hindered in its transfer and ultimately leading to the loss of heat recovery and mass transfer capacity of the system. In this study, a novel type of jacketed hollow fiber vacuum membrane distillation module (J-HF-VMD-M) has been successfully developed. It has the dual functions of “feed evaporation” and “vapor condensation”, which is helpful in reducing the volume and complexity of the system. Based on the structural characteristics of the jacketed module, a “Synergistic heat transfer model of double boundary layers” (SHT-DBL Model) is proposed for the first time. Compared with the previous “independent heat transfer” method between boundary layers, the “synergistic heat transfer” can overcome the above challenges more effectively. Compared with the non-heat recovery process in experimental range, the equivalent membrane distillation flux of the jacketed-type heat recovery process increased by 246.1 %, especially the gain output ratio increased by 145.1 %, and the corresponding increment is more significant than that of the traditional heat recovery process.