Expansion Process Research Articles

Abundant vortex dynamics in spin-1 Bose–Einstein condensates induced by Rashba spin–orbit coupling

The paper studies the dynamics of vortices evolved from the ring dark solitons (RDSs) in spin-1 Bose–Einstein condensates with Rashba spin–orbit coupling (SOC). We find that the SOC induces abundant vortex dynamic phenomena, and the numbers of vortex dipoles and lump-like solitons are all determined by the initial depths’ weighted average of the three components of RDSs. For a shallow RDS, the ring first expands and then contracts into a mini RDS, eventually evolving into late vortex dipoles. For the RDS with a moderate initial depth, during the contraction of the ring, it evolves into early vortex dipoles or lump-like solitons, and they evolve back into the mini RDS, which then evolves into late vortex dipoles during the expansion process. For the deep and black RDSs, the early vortex dipoles continue to transform between vortex dipoles and lump-like solitons without forming mini RDS. The motions of vortices mentioned above have a higher disorder degree than that in the system without SOC, because the SOC breaks the mirror symmetry of the condensate. Finally, we reveal that the SOC strength only influences the number of late vortex dipoles, while it does not affect the number of early vortex dipoles and lump-like solitons. Stronger SOC intensity results in a shallower critical depth, and vortices form only at or beyond this depth.

The Role of Tissue Expansion Before Baclofen Pump Insertion in the Pediatric Population.

Tissue expansion is a well-established technique for soft tissue reconstruction in the pediatric population. We present a case series of this technique to create a safe pocket for baclofen pump insertion to minimize risk of complications including pump migration, extrusion, wound dehiscence and infection. A case series of 3 pediatric patients undergoing tissue expansion prior to baclofen pump insertion at a single center in Melbourne. The expansion procedure was performed by senior surgeon N Low in all cases, and patients followed up 6 months after expander-pump exchange. The study was conducted over a 4-year period 2019 to 2023. We suffered 2 minor complications with the tissue expansion process including cellulitis and pump deflation. Neither complication precluded further tissue expansion nor led to premature removal of the expander. All patients proceeded to safely complete expander-pump exchange. One patient suffered a small (6 mL) abdominal seroma associated with pump insertion, which required no intervention. All patients have had a successful outcome 6 months after pump insertion. We describe a reliable and reproducible approach in creating a safe abdominal wall pocket to better accommodate baclofen pump insertion. Our series has overcome the imbalance between device size and abdominal wall pocket, now offering an alternative approach to achieve the safe delivery of intrathecal baclofen in the pediatric population.

Quantifying sandstone crack extension and expansion via deep learning methods

This study investigates the damage evolution of sandstone under loading stresses, which can lead to irreversible plastic deformation and reduced project stability service life. To achieve this objective, we identify and quantify the emergence and expansion process of sandstone cracks using deep learning methods. Specifically, our approach employs a crack segmentation model enhanced by an attention mechanism, achieving a remarkable effective crack detection MIoU of 93.38. Through the application of connectivity domain analysis, skeleton extraction, and orthogonal projection techniques, we extract crucial crack parameters, which are subsequently formulated into equations to determine their actual dimensions. These evolving parameter variations serve as the foundation for predicting the sandstone's entire damage progression, encompassing both microscopic crack growth and eventual catastrophic failure preceding macroscopic manifestation of damage. Validation of our method through uniaxial compression tests on sandstone specimens confirm its efficacy and practical applicability. In conclusion, this study presents a novel framework for quantifying sandstone crack evolution, providing invaluable insights into the intricate mechanisms governing damage fracture progression in rocks.

Numerical study on structural design and mechanical analysis of anti-migration tracheal stent with non-uniform Poisson's ratio

Stent migration is one of the common complications after tracheal stent implantation. The causes of stent migration include size mismatch between the stent and the trachea, physiological movement of the trachea, and so on. In order to solve the above problems, this study designed a non-uniform Poisson ratio tracheal stent by combining the size and structure of the trachea and the physiological movement of the trachea to improve the migration of the stent, meanwhile ensuring the support of the stent. In this study, the stent corresponding to cartilage was constructed with negative Poisson's ratio, and the stent corresponding to the circular connective tissue and muscular membrane was constructed with positive Poisson's ratio. And four kinds of non-uniform Poisson's ratio tracheal stents with different link lengths and negative Poisson's ratio were designed. Then, this paper numerically simulated the expansion and rebound process of the stent after implantation to observe the support of the stent, and further simulated the stretch movement of the trachea to calculate the diameter changes of the stent corresponding to different negative Poisson's ratio structures. The axial migration of the stent was recorded by applying different respiratory pressure to the wall of the tracheal wall to evaluate whether the stent has anti-migration effect. The research results show that the non-uniform Poisson ratio stent with connecting rod length of 3 mm has the largest diameter expansion in the negative Poisson ratio section when the trachea was stretched. Compared with the positive Poisson's ratio structure, the axial migration during vigorous breathing was reduced from 0.024 mm to 0.012 mm. The negative Poisson's ratio structure of the non-uniform Poisson's ratio stent designed in this study did not fail in the tracheal expansion effect. Compared with the traditional stent, the non-uniform Poisson's ratio tracheal stent has an anti-migration effect under the normal movement of the trachea while ensuring the support force of the stent.

MUSE: an open-access platform for urban expansion simulation with multitype patch generation engine and multilevel morphology regulation

Urban expansion models (UEMs) help unfold the mechanism, future pathways, and relevant repercussions of urban landscape dynamics. Although a plethora of UEMs have been developed, the field of open-access modeling platform for urban expansion simulation still presents gaps in terms of representing urban development events, regulating multilevel urban morphologies, and reflecting underlying regularities of physical urban growth. This study develops an open-access Multiengine Urban Expansion Simulation (MUSE) platform together with software that addresses some of these limitations. MUSE employs patch-based concepts and different patch generation engines to represent urban development events of distinctive types, enabling control over spatial morphology at landscape, class and patch levels. Moreover, MUSE incorporates two general regularities on urban development waves and urban diffusion and coalescence to govern physical urban expansion processes. Experiments in two cities examine MUSE’s ability in simulating realistic urban dynamics, and a series of synthetic experiments verify the operational behavior of the patch generation engines. These experiments show that MUSE can simulate a range of urban expansion types, including infill, edge growth and leapfrog expansion, and various morphologies, such as aggregated, sprawl, fragmented and compact. MUSE can empower practitioners to better project, analyze and understand complex urbanization dynamics.

Urban Street Landscape Design System Driven by Optimized Genetic Algorithm

With the acceleration of urbanization in China, urban and rural construction land continues to expand. In order to avoid “urban street view disease” in the process of urbanization, dynamic simulation of urban street view land is of great significance. The dynamic model of urban street view land can simulate the dynamic expansion process of street view concretely and effectively, and predict the distribution and form of urban street view land in the future more accurately. How to improve the accuracy of urban street view dynamic model based on geographic cellular automata has always been the direction of unremitting exploration in academic circles. In view of the limitations of the traditional genetic algorithm model, this study constructs a genetic algorithm-logistic regression model, and takes Chengdu-Chongqing Economic Zone as a case, and optimizes the best regression coefficient of the logistic regression model through genetic algorithm fitting, so as to realize the accurate simulation of the dynamic change of urban street view land.

Dynamics of change in the polytropic exponent in the expansion stroke of diesel

In the article is considered the problem of achieving the optimal duration of the working stroke of a diesel engine piston during the expansion process and obtaining the maximum efficiency coefficient (EC). For this purpose, a hypothesis was put forward about the pumping action of the piston on the flow of expanding gases during the power stroke of an diesel internal combustion engine (ICE) as the piston moves from upper dead point (UDP) to bottom dead point (BDP).At a certain moment of expansion, the rate of the flow of expanding gases turns out to be equal to the rate with which the same flow is slowed down by the moving piston.The equality of these rates leads to the formation of a flow break line and has a significant impact on the nature of the change in the polytropic exponent; the value of the exponent becomes equal to one: n = 1. This indicates that the optimum duration of the engine’s working stroke has been achieved and corresponds to the maximum power that can be removed during the diesel engine’s operating cycle. An experimental relation was obtained between the initial p1 and final p2 pressures in the cylinder during gas expansion with the gas flow rate and the rate of deceleration of this flow due to the pumping action of the piston. An equation for the continuity of gas flow has been compiled for the process of gas expansion in the cylinder of an ICE with closed gas exchange organs. Based on this equation, the numericalvalue of the acceleration of gravity in the cylinder of ICE is obtained: gф ≈ 8,7 м/с2 < g, which confirms the pumping action of the piston. A theoretical (and graphical) dependence of the polytropic process exponent on the flow rate of expanding gases is obtained. The dependence allows to calculate the polytropic exponent and establish the gas relaxation period, indicating the achievement of the optimal duration of the piston stroke.

Legitimacy under pressure: Energy firms’ expansion in countries with weak environmental performance

Environmental pollution and climate change have become alarming global issues in the process of rapid economic growth and accelerated internationalization. Due to the environmentally sensitive nature of energy firms, maintaining their legitimacy in the international expansion process, especially in countries with weak environmental performance, is a largely underexplored area in the existing literature. Building on legitimacy as a theoretical perspective, this study examines energy firms’ international expansion patterns when facing environmental pressure. We analyze a dataset of 2134 cross-border mergers and acquisitions conducted by energy firms between 1992 and 2019 to examine the impact of host-country environmental performance, encompassing environmental health (i.e., environmental conditions that affect human well-being) and climate change (i.e., variations in weather patterns), on their expansion. We also investigate the boundary conditions underpinning this relationship. We find that firm-level internalization capability and country-level diplomatic relations make energy firms appear legitimate to their internal and external audiences, respectively. The findings bring fresh insights to the literature on international expansion under environmental threats, enrich the legitimacy perspective, and outline practical implications for firms to preserve and enhance legitimacy for international growth. Additionally, we discuss important policy implications for governments to strengthen regulatory standards on environmental issues in support of sustainable world development.

Single-shot 20-fold expansion microscopy.

Expansion microscopy (ExM) is in increasingly widespread use throughout biology because its isotropic physical magnification enables nanoimaging on conventional microscopes. To date, ExM methods either expand specimens to a limited range (~4-10× linearly) or achieve larger expansion factors through iterating the expansion process a second time (~15-20× linearly). Here, we present an ExM protocol that achieves ~20× expansion (yielding <20-nm resolution on a conventional microscope) in a single expansion step, achieving the performance of iterative expansion with the simplicity of a single-shot protocol. This protocol, which we call 20ExM, supports postexpansion staining for brain tissue, which can facilitate biomolecular labeling. 20ExM may find utility in many areas of biological investigation requiring high-resolution imaging.

Investigating the expansion behavior of silicon nitride nanopores

Nanopores are a single-molecule detection platform that has attracted more and more researchers’ attention, but so far there is still a lack of systematic research on their stability. In this study, we investigated the mechanism behind the expansion behavior of solid-state nanopores and its effect on the electrical properties of nanopores. Through the analysis of electron energy loss spectroscopy, it was found that the expansion process of nanopores is accompanied by the loss of silicon elements. Three nanopore expansion models can well explain the differential impact of silicon element loss in different regions on the electrical properties of nanopores. Molecular dynamics simulations analyzed the differences in nanopore conductivity and expansion rate corresponding to different expansion models from the perspective of single-atom loss. Finally, we demonstrated that chemical modification can isolate direct contact between the nanopore wall and the solution, thereby greatly delaying the expansion behavior of solid-state nanopores.

Flash Vacuum Expansion of Maradol Papaya (Carica papaya L.) for Producing an Antioxidant-Potential Dairy Beverage Fermented by Limosilactobacillus fermentum J24

This study aimed to evaluate the fermentative capacity of the strain Limosilactobacillus fermentum J24 in a dairy beverage with papaya puree obtained through the flash vacuum expansion (FVE) process. Changes in phenolic content and antioxidant capacity during fermentation were investigated. Results showed that the dairy beverage with the control puree exhibited higher microbial growth than the FVE puree. Phenolic content increased during fermentation in both formulations. However, the antioxidant capacity was higher in the dairy beverage with control puree. A Pearson correlation analysis revealed a strong positive correlation between microbial load and antioxidant properties in the dairy beverage with control puree. In conclusion, the control puree promoted a higher growth of Limosilactobacillus fermentum J24 and better antioxidant properties in the papaya dairy beverage. These findings lay the groundwork for developing a potential functional dairy beverage based on papaya, effectively utilizing the fruit, reducing pollution, and adding value. This study also opens avenues for further research and development in functional dairy beverages, particularly those incorporating fruit-based ingredients.

Urban expansion in highly populous East Asian megacities during 1990–2020: Tokyo, Seoul, Beijing, and Shanghai

The world is experiencing unprecedented urbanization, particularly through the continuous growth of megacities, leading to significant urban land expansion. The spatial layout and growth patterns of urban areas play a critical role in determining cities' sustainable development. However, the optimal path for cities undergoing rapid urbanization remains uncertain. This study examines four megacities—Tokyo, Seoul, Beijing, and Shanghai—and, from the perspective of urban land density, compares their patterns and processes of land expansion in 1990, 2000, 2010, and 2020. Findings reveal that the urban land area of China's megacities has expanded nearly fourfold over the past three decades. Meanwhile, Tokyo and Seoul have adopted a polycentric urban structure, becoming increasingly compact. In contrast, Beijing and Shanghai are only beginning to show signs of polycentric development. The study concludes that cities experiencing rapid growth should not impose excessive limitations on urban expansion. Polycentric and compact development has become a critical strategy for megacities. These insights offer valuable guidance for urban planning and sustainable development in both established and emerging megacities across East Asia.

How Green Space Justice in urban built-up areas affects public mental health: a moderated chain mediation model.

Green and blue spaces, as crucial components of urban ecosystems, significantly impact the physical and mental health of residents. However, the mechanisms through which Green/Blue Space Justice influence residents' health remain unclear. This study aims to explore the impact of green spaces on public psychological responses, physical activity, and mental health from a justice perspective, and to examine the moderating role of blue spaces in this relationship. The research was conducted in selected communities within the Chang-Zhu-Tan urban agglomeration in Hunan Province, China. A total of 801 valid questionnaires were collected through field visits and online surveys. The study uses an improved Gaussian-based two-step floating catchment area (2SFCA) method to assess green space accessibility. Data were analyzed using structural equation modeling (SEM) and moderation effect analysis to reveal the relationships between variables. The findings indicate that Green Space Justice has a significant positive impact on psychological responses, physical activity, and mental health; psychological responses and physical activity play crucial mediating roles between Green Space Justice and mental health; and Green Space Justice significantly affects mental health through a chain mediation path involving psychological responses and physical activity. Moreover, Blue Space Justice significantly moderates the impact of Green Space Justice on psychological responses and physical activity, but does not have a significant direct impact on mental health. This study enriches the theory of Green Space Justice by revealing the mechanisms through which it influences mental health via psychological responses and physical activity. It provides a scientific basis for the development of healthy cities. Additionally, it recommends that urban planning should prioritize the equitable distribution and high accessibility of both green and blue spaces to comprehensively enhance residents' physical and mental well-being. Policymakers should consider prioritizing the accessibility of high-quality green spaces for vulnerable communities during urban renewal and expansion processes to reduce social health inequalities and promote broader public health outcomes.

Conceptual framework to incorporate drainage solutions in the urban open space system

Cities are increasingly dealing with challenges regarding the negative impact of rapid and mismanaged urbanization. Therefore, city planning must cope with the natural environment limitations, seeking a balance between the human activities and the well-functioning of the hydrologic cycle. This work aims to present a conceptual framework able to properly integrate the stormwater dynamics into the open spaces system in a functional way, establishing a Hydrological Interest Area, HIA, to structure urban expansion integrated into and respecting watershed natural processes. The initial step is to define a HIA, primarily consisting of open spaces that can be used for supporting urban drainage functions and to order land use in the urban expansion process. This delimitation offers the background for interpreting the watershed in three functional arches, especially covering the upstream, mid-reach and downstream areas of the basin, guiding the design of a set of flood mitigation interventions focusing on the use of Blue-Green Infrastructure. To illustrate and validate the proposed methodological framework, the design is evaluated by a flood modeling tool, using a hydrological-hydrodynamic cell-model. A case study was driven in the Bambu Watershed, a rapidly developing area in the municipality of Maricá, Rio de Janeiro, Brazil. The proposed intervention includes an urban expansion scenario for a low impact development on flood behavior alongside with four parks: an upstream park with reservoirs, two multifunctional floodable urban parks, and a park dedicated to lagoon restoration. This plan complements riverbed modifications designed to enhance water discharge. The simulation showed significant reduction of water depths with a consequent decrease in exposure of buildings and roads, especially in the most critical region of the watershed. This framework highlights the importance of a multifunctional approach in land use and serves as a robust foundation for controlling urban expansion and proposing projects.

Tissue Expanders for Hair Restoration in the Scalp: Overexpansion Does Matter.

Tissue expansion to treat of alopecia of the scalp is the corner stone to restore a hairy scalp, although the process of expansion takes time to achieve a satisfactory result. Overexpansion could help in managing limited areas of donor sites or inadequate supply of tissue expanders. Meticulous patient selection and follow-up is the key to avoid complications and to obtain good results. Tissue expanders were used to restore the hairy scalp after burns or direct trauma. More than one tissue expander could be used simultaneously or after the first stage; the expander could be reused for the same patient for further expansion in another part of the hairy scalp to complete hair restoration and removal of all scar tissue. Twenty-five patients with alopecia underwent hair restoration with 28 expanders, all of which were overexpanded. Three pairs of expanders were used simultaneously in three patients. Three expanders were reused in the other three patients after removal to complete the second stage. All patients showed complete restoration of their hairy scalp with minimal complications and a high rate of satisfaction. Tissue expansion is a cornerstone in the treatment of scalp alopecia. Meticulous patient selection and follow-up provided the most satisfactory results, with fewer postoperative complications. Overexpansion can be safely used.

Flash vacuum expansion process promotes increased viability of Limosilactobacillus fermentum J24 in papaya-based beverages under simulated digestion

The processing of papaya generates large amounts of agro-industrial waste, which have become a pollution problem due to the lack of proper management systems. Agro-industrial papaya waste, such as unused peel and pulp, still serves as a reservoir of bioactive compounds, vitamins, and fiber. Therefore, it is important to assess sustainable ways to utilize these waste products. The consumption of antioxidant compounds, fiber and probiotics improves consumer health by preventing or reducing the incidence of diseases. Flash vacuum expansion (FVE) process has been shown to efficiently release antioxidant compounds from vegetable matrices, allowing the use of peel and fruit pulp. This study evaluated the ability of Limosilactobacillus fermentum J24 (isolated from cheese) to ferment a beverage based on papaya puree generated through FVE. It was found that the bacteria exhibited better growth in traditionally generated purees (control), reaching values of 8.5 Log CFU/mL. Before fermentation phenolic compounds and antioxidant capacity was higher in flash-generated puree beverages with values above 20 mg GAE/100 g fresh weight for total phenols and 50 m moles TE/100 g fresh weight for antioxidant capacity. After fermentation, phenolic compounds and antioxidant capacity was higher in control puree beverages. After simulated digestion, higher cell viability was observed in flash puree beverages. FVE process released more intracellular compounds, challenging the bacteria to take metabolic pathways to adapt to a more complex environment, promoting a greater adaptation to the digestive phase, and preserving probiotic potential

Experimental and numerical study on bubble pulsation characteristics of underwater explosions with multiple charges

This study examines the processes of expansion, merging, and collapse of multiple underwater explosion bubbles through experimental and numerical methods. A small-scale underwater explosion experiment was conducted in a water tank. The behaviors of three and four bubbles during expansion, merging, and collapse were captured using high-speed photography, and the effects of the quantity and spacing of the explosive charge on the bubble dynamics were analyzed. The results indicate that the evolution of bubble behavior in multiple charge underwater explosions, including the bubble period and radius, is significantly influenced by the spacing between charges. With a decrease in the ratio of the charge spacing to the bubble radius, the period of the merged bubble increases progressively. Independent small bubbles do not interact when the distance between charges exceeds 1.3 times the bubble radius. Furthermore, when the ratio of the spacing to the initial bubble radius (L/rb) is between 1.0 and 1.3, multiple bubbles merge during the contraction phase. When the spacing is less than the maximum radius of the bubbles, multiple bubbles inevitably merge, with fusion occurring during the expansion phase.

Gas kick dynamic circulation in MPD operations with water based drilling fluid: maximum casing pressure modeling and validation

The use of water-based drilling fluids enables the rapid detection of a gas influx by pit gain monitoring due to the low solubility of gases in the aqueous medium. Moreover, as the influx remains as a free gas, it undergoes a process of expansion the further it rises through the well, changing the pressure profiles and producing a pressure peak when it reaches the surface. Therefore, the gas influx must be controlled appropriately. Otherwise, the maximum pressure experienced during the kick circulation may exceed the safety limits of surface equipment, placing the operation and the rig crew in a hazardous situation. The Managed Pressure Drilling (MPD) technique allows for a more precise detection and control of the influx while retaining the ability to circulate dynamically small volumes of gas kick through the riser, minimizing the risks involved and the non-productive time (NPT). However, the decision of when to apply dynamic or conventional circulation techniques must be considered carefully, taking into account factors such as predictions of pressure peaks, as well as intensity and volume of the kick. In this way, it is paramount that the maximum pressure during the circulation be estimated before the operation begins to ensure that the decision is made correctly. This paper presents the results of a gas kick circulation simulator specifically developed to predict pressure peaks. This simulator uses a mathematical model based on algebraic equations whose solution requires low computational effort and, therefore, regarding gas kick incidents, is an interesting tool that can aid in guiding decision-making. The results of pressure peaks were successfully validated by employing literature data, experimental drilling setup runs and simulations performed in a commercial software largely consolidated in the petroleum industry: Drillbench.

Phase 3 Clinical Trial Candidate Rilparencel Demonstrates Consistent Phenotypic Characteristics during Ex Vivo Culture Expansion Process

Phase 3 Clinical Trial Candidate Rilparencel Demonstrates Consistent Phenotypic Characteristics during Ex Vivo Culture Expansion Process

The spatio-temporal evolution of shock wave pressure induced by laser: Effects of laser parameters and confinement layer

The spatio-temporal distribution of the shock wave pressure on the surface of the target is the key to the performance of laser shock processing (LSP), which is mainly determined by the laser parameters and the confinement layer. The two-dimensional kinetic simulations of the expansion process of the shock wave induced by irradiation of an aluminum target with nanosecond laser pulses are performed. It is found that by controlling the gap between the rigid confinement layer and the aluminum target, and the interval time between the double pulse laser pulses, multiple peaks appear on the shock wave pressure-time curve of the aluminum target surface, and the value and interval time of each peak will change.