Passive Liquid Research Articles

When Do Systematic Internalisers Choose to Provide Passive Liquidity to Investors?

When Do Systematic Internalisers Choose to Provide Passive Liquidity to Investors?

A 3D-Printed Bionic Membrane with Autonomously Passive Unidirectional Liquid Transfer Capability for Water Condensation, Collection, and Purification.

Interfacial solar vapor generation is a promising technology for alleviating the current global water crisis, and the evaporation rate and efficiency have approached the theoretical limit. In a practical interfacial evaporation water purification system, the collection rate of purified water is typically lower than the evaporation rate. Passive collection devices based on gravity are susceptible to environmental influences and exhibit low collection efficiency, while active collection devices consuming external energy suffer from complex device systems and extra energy consumption. Given that both collection devices are nonselective and unable to distinguish contaminants mixed in the vapor, bionic membranes with autonomously passive and unidirectional water transfer capacity are developed through 3D printing for efficient water collection. More importantly, the bionic membranes are capable of high-speed water transportation without the need for external energy or gravity drive and liquid-selective transportation for separating oily pollutants from the collected products. The directional transport property facilitates the modular assembly of the bionic membrane, extending its application to practical large-scale solar-driven seawater desalination systems.

Active Fréedericksz Transition in Active Nematic Droplets

Active nematic liquid crystals have the remarkable ability to spontaneously deform and flow in the absence of any external driving force. While living materials with orientational order, such as the mitotic spindle, can self-assemble in quiescent active phases, reconstituted active systems often display chaotic, periodic, or circulating flows under confinement. Quiescent active nematics are, therefore, quite rare, despite the prediction from active hydrodynamic theory that confinement between two parallel plates can suppress flows. This spontaneous flow transition—named the active Fréedericksz transition by analogy with the conventional Fréedericksz transition in passive nematic liquid crystals under a magnetic field—has been a cornerstone of the field of active matter. Here, we report experimental evidence that confinement in spherical droplets can stabilize the otherwise chaotic dynamics of a 3D extensile active nematics, giving rise to a quiescent—yet still out-of-equilibrium—nematic liquid crystal. The active nematics spontaneously flow when confined in larger droplets. The composite nature of our model system composed of extensile bundles of microtubules and molecular motors dispersed in a passive colloidal liquid crystal allows us to demonstrate how the interplay of activity, nematic elasticity, and confinement impacts the spontaneous flow transition. The critical diameter increases when motor concentration decreases or nematic elasticity increases. Experiments and simulations also demonstrate that the critical confinement depends on the confining geometry, with the critical diameter in droplets being larger than the critical width in channels. Biochemical assays reveal that neither confinement nor nematic elasticity impacts the energy-consumption rate, confirming that the quiescent active phase is the stable out-of-equilibrium phase predicted theoretically. Further experiments in dense arrays of monodisperse droplets show that fluctuations in the droplet composition can smooth the flow transition close to the critical diameter. In conclusion, our work provides experimental validation of the active Fréedericksz transition in 3D active nematics, with potential applications in human health, ecology, and soft robotics. Published by the American Physical Society 2024

Active nematic-isotropic interfaces on flat surfaces: Effects of anchoring, ordering field and activity

A surface in contact with the isotropic phase of a passive liquid crystal can induce nematic order over distances that range from microscopic to macroscopic when the nematic-isotropic interface undergoes an orientational-wetting transition. If the nematic is active, what happens to the interface? Does it propagate and, if it does, is its structure different from the passive one? In this paper, we address these questions. We investigate how the active nematic-isotropic interface is affected by the anchoring strength of the surface, the bulk ordering field and the activity. We find that while passive interfaces are one-dimensional the active ones exhibit two dynamical regimes: a passive-like regime and a propagating regime where the interfaces propagate until the entire domain is active nematic. Active interfaces break the translational symmetry within the interfacial plane above a threshold activity, where the active nematic fluctuations, which are ultimately responsible for the emergence of an active turbulent nematic phase, drive non-steady dynamical interfacial regimes.

First Order Alignment Transition in an Interfaced Active Nematic Fluid.

We investigate experimentally the dynamic phase transition of a two-dimensional active nematic layer interfaced with a passive liquid crystal. Under a temperature ramp that leads to the transition of the passive liquid into a highly anisotropic lamellar smectic-A phase, and in the presence of a magnetic field, the coupled active nematic reorganizes its flow and orientational patterns from the turbulent into a quasilaminar regime aligned perpendicularly to the field. Remarkably, while the phase transition of the passive fluid is known to be continuous, or second order, our observations reveal intermittent dynamics of the order parameter and the coexistence of aligned and turbulent regions in the active nematic, a signature of discontinuous, or first order, phase transitions, similar to what is known to occur in relation to flocking in dry active matter. Our results suggest that alignment transitions in active systems are intrinsically discontinuous, regardless of the symmetry and momentum-damping mechanisms.

Performance and compensation method of first-order liquid crystal beam-steering system under continuous wave laser irradiation

The effects of laser irradiation thermal deposition on the performance degradation of liquid crystal (LC) devices in high-power laser systems are extremely vital. In this study, the first-order beam-steering system (FBS) was developed using a passive liquid crystal polarization grating (LCPG) and liquid crystal adjustable wave-plate (LCAW). The LCPG was prepared by holographic exposure technology, and the LCAW was prepared using the standard LC cell preparation process. We investigated the influences of diffraction efficiency of FBS under a 1070-nm continuous-wave (CW) laser irradiation. The energy is concentrated in the −1st order at first. When the half-wave retardation was reached, all the energy is concentrated in the +1st order (∼97 %), and the beam is deflected. Once the phase retardation decreases below the half-wave retardation, the energy gradually reconcentrates in the −1st order. When the LCAW fails, the diffraction the energy is refocused to the −1st order by the LCPG. The results indicated that both thermal deposition and driving voltage reduce the phase retardation of the LCAW, generating a variation of energy between in ±1st orders. By reducing the driving voltage, this half-wave retardation can be recovered under a certain half-wave voltage and laser power density, and the diffraction efficiency of the +1st order can be compensated to ∼97 %. If the reduced phase retardation is not less than half-wave, the FBS can still be modulated in high-power continuous lasers. Our research provides a reference for the development of beam-steering technology based on LC materials in high-power laser systems.

Preventing Thermal Runaway Propagation in Lithium-ion Batteries using a Passive Liquid Housing

Lithium-ion batteries (LIBs), due to their high energy density, long lifespan, and low self-discharge, are widely used in various applications. However, they are challenged by the risk of thermal runaway and thermal degradation, so they require effective thermal management system. In this study, we investigated the application of a water-inclusive housing structure to battery modules to prevent thermal runaway propagation and enhance thermal management. The thermal and electrochemical behaviors of the batteries were analyzed using the ANSYS Fluent simulator. Through simulations, we determined the optimal cell spacing of the water-housing module that maximizes energy density while ensuring thermal stability. Our results indicate that a water housing module composed of 20 cylindrical cells(10s2p) with a cell spacing of 4 mm can effectively prevent thermal runaway propagation and reduce cell temperature by approximately 60% during normal discharge, while maintaining 80% of the volumetric energy density of a conventional module. Furthermore, the reliability of our simulation results was validated through thermal runaway and normal discharge tests. The proposed water housing method holds great promise in preventing thermal runaway propagation and enhancing thermal stability of LIB modules, thereby mitigating the risk of fire and thermal degradation during normal discharge.

Lamellar structured Ce-S-NC heterogeneous electrocatalyst as the highly durable cathode for passive direct liquid fuel cells

Passive direct liquid fuel cells are promising power generation devices with the advantages of convenient transportation, storage for liquid fuel and high power density. This paper focuses on improving the intrinsic electrocatalytic performance and durability of nitrogen-doped carbon (N-C) cathodic electrocatalysts. Then, lamellar structured Ce-S-NC heterogeneous electrocatalyst was synthesized and used as a highly durable cathode for two types of passive direct liquid fuel cells, i.e., direct methanol fuel cells (DMFCs) and direct borohydride fuel cells (DBFCs). In this work, the effect of the S/C molar ratio on the microstructure and electrocatalytic performance of the Ce-S-NC electrocatalysts was investigated, and excellent intrinsic oxygen reduction reaction activity was obtained at an S/C molar ratio of 0.15. The peak power densities of Ce-S-NC based DMFCs reached up to 12.5, 23.6 and 41.9 mW·cm−2 at 20, 40 and 60 °C, respectively. The peak power densities of 59.3, 84.6 and 132.6 mW·cm−2 were obtained in Ce-S-NC based DBFCs at 20, 40 and 60 °C, respectively. In the durability tests, both the Ce-S-NC based air-breathing DBFCs and passive DBFCs showed the stable operation than that of N-C and Ce-NC. When the current density increased from 50 to 150 mA·cm−2, the Ce-S-NC based DBFC can be operated for 882 h, and only 34 and 91 h for that of N-C and Ce-NC. The electrochemical impedance spectroscopy tests proved Ce-S-NC based DBFC showed the faster mass transfer efficiency. The outstanding durability of Ce-S-NC is mainly attributed to the improved defect density and mass transfer.

Deep attentive survival analysis in limit order books: estimating fill probabilities with convolutional-transformers

One of the key decisions in execution strategies is the choice between a passive (liquidity providing) or an aggressive (liquidity taking) order to execute a trade in a limit order book (LOB). Essential to this choice is the fill probability of a passive limit order placed in the LOB. This paper proposes a deep learning method to estimate the filltimes of limit orders posted in different levels of the LOB. We develop a novel model for survival analysis that maps time-varying features of the LOB to the distribution of filltimes of limit orders. Our method is based on a convolutional-Transformer encoder and a monotonic neural network decoder. We use proper scoring rules to compare our method with other approaches in survival analysis, and perform an interpretability analysis to understand the informativeness of features used to compute fill probabilities. Our method significantly outperforms those typically used in survival analysis literature. Finally, we carry out a statistical analysis of the fill probability of orders placed in the order book (e.g. within the bid-ask spread) for assets with different queue dynamics and trading activity.

Biofilms as self-shaping growing nematics.

Active nematics are the nonequilibrium analogue of passive liquid crystals. They consist of anisotropic units that consume free energy to drive emergent behaviour. Like liquid crystal molecules in displays, ordering and dynamics in active nematics are sensitive to boundary conditions. However, unlike passive liquid crystals, active nematics have the potential to regulate their boundaries through self-generated stresses. Here, we show how a three-dimensional, living nematic can actively shape itself and its boundary to regulate its internal architecture through growth-induced stresses, using bacterial biofilms confined by a hydrogel as a model system. We show that biofilms exhibit a sharp transition in shape from domes to lenses upon changing environmental stiffness or cell-substrate friction, which is explained by a theoretical model that considers the competition between confinement and interfacial forces. The growth mode defines the progression of the boundary, which in turn determines the trajectories and spatial distribution of cell lineages. We further demonstrate that the evolving boundary and corresponding stress anisotropy define the orientational ordering of cells and the emergence of topological defects in the biofilm interior. Our findings may provide strategies for the development of programmed microbial consortia with emergent material properties.

Laser microstructuring of extremely-thin vapor chamber with hybrid configuration for excellent heat dissipation

Efficient thermal management has become a bottleneck for the further development of highly integrated and high-power optoelectronic devices. Vapor chambers (VCs) based on the passive liquid–vapor phase-change process have attracted increasing attention due to their extraordinary thermal management capabilities together with easy-to-assemble advantages. Nowadays, as optoelectronic devices continuously get more compact and miniaturized, there exists a great demand to develop high-performance ultra-thin VCs with overall thicknesses below 0.3 mm. However, the demand has been seldom reached by present VCs with either the layered or spaced configurations. Here, we demonstrated an extremely-thin VC (ETVC) with a three-region hybrid configuration fabricated via a facile laser micro/nano structuring approach, reaching a remarkable effective thermal conductivity of 12032 W/(m⋅K) with an overall thickness of only ∼ 0.22 mm. Cross-arrayed micro-protrusions were fabricated on both the evaporation and condensation regions of the lower plate of the VC, connected by water/vapor passages composed of parallel micro-channels. The micro-channels were designed to make a layered-spaced hybrid configuration to accommodate the fast flow of both water and vapor. The surfaces of both the micro-protrusions and micro-channels were covered with plentiful finer features to render them excellent wicking performances. Such a laser microstructured three-region hybrid configuration enhances all main processes inside a VC (i.e., water evaporation, water condensation, and water/vapor transportation), boosting the self-driven circulation of water/vapor to efficiently homogenize temperature under different heat fluxes. We believe this work can lay a promising rationale for designing and fabricating highly-efficient highly-compact VCs for the increasing thermal management demand within high-end optoelectronics.

Trader positions and aggregate portfolio demand

In electronic, liquid markets traders frequently change their positions. We posit that the asymmetry in the distribution of these position changes carries important information about portfolio demand in the market. We use skewness to capture the asymmetry in position changes and from this distribution, we construct a market-wide measure for portfolio demand. Using a rich regulatory data set on S&P 500 E-mini futures, we show that this portfolio demand measure has a positive impact on prices. Decomposing our measure of portfolio demand into aggressive, passive and mixed components, we show that a one standard deviation increase in passive liquidity demand is associated with a 0.5 tick rise in prices for S&P 500 E-mini futures. Finally, we show that the distribution of position changes is crucial for explaining the execution cost of large traders.

Patterning Wettability for Open-Surface Fluidic Manipulation: Fundamentals and Applications.

Effective manipulation of liquids on open surfaces without external energy input is indispensable for the advancement of point-of-care diagnostic devices. Open-surface microfluidics has the potential to benefit health care, especially in the developing world. This review highlights the prospects for harnessing capillary forces on surface-microfluidic platforms, chiefly by inducing smooth gradients or sharp steps of wettability on substrates, to elicit passive liquid transport and higher-order fluidic manipulations without off-the-chip energy sources. A broad spectrum of the recent progress in the emerging field of passive surface microfluidics is highlighted, and its promise for developing facile, low-cost, easy-to-operate microfluidic devices is discussed in light of recent applications, not only in the domain of biomedical microfluidics but also in the general areas of energy and water conservation.

Advanced hybrid thermal management system for LTO battery module under fast charging

Nowadays, the use of electric vehicles (EVs) equipped with lithium-ion (Li-ion) batteries, has been growing every day. Li-ion batteries' performance, effectiveness, and safety importantly depend on thermal management systems (TMSs). In this paper, a novel and advanced hybrid TMS for cooling the battery module, using phase change material (PCM) and liquid cooling, has been experimentally studied. Passive PCM heat buffer plate and liquid cooling plates are connected from down and lateral sides, respectively. Cooling with natural convection could not preserve the module temperature in the desired operational temperature at fast charging. The average module temperature for the charging and discharging process reaches 41.4 °C and 43 °C respectively. The results display the module temperature equipped with a PCM heat buffer plate at the end of the charging and discharging process reaches 35.8 °C and 36.2 °C which experience a 13.3% and 15.8% temperature reduction, respectively. Using the hybrid cooling system, the module temperature at the end of the charging and discharging process reaches 31.2 °C and 31.8 °C which experience a 24.6% and 26% temperature reduction compared with natural convection. Moreover, using the hybrid cooling system the temperature uniformity has been improved by 56% and 34.8% for the charging and discharging process, respectively.

Design of low-cost drive circuit for passive liquid crystal optical device

Design of low-cost drive circuit for passive liquid crystal optical device

A metaheuristic‐based optimum tuning approach for tuned liquid dampers for structures

SummaryThis study focuses on the optimization of tuned liquid dampers (TLDs) by using metaheuristic methods using a natural phenomenon as inspiration. Unlike tuned mass dampers (TMDs), TLDs consist of two parts of bodies that contain the passive liquid that is stationary and the active part of the liquid that involves in sloshing. To optimize the amount of optimum active and passive liquids by finding the best dimensional properties of the liquid tank, a two‐degree‐of‐freedom (DOF) model was used as TLD in the dynamic analysis used in the optimization that aims to reduce the maximum displacement of the structure under earthquake excitations. For this purpose, water, oil, and glycerin liquids were selected for TLD. TLD parameters were optimized with the help of Jaya algorithm, flower pollination algorithm (FPA), harmony search (HS) algorithm, and teaching–learning‐based optimization (TLBO). Total acceleration and maximum displacement were evaluated after optimization. The performance of TLD under earthquake excitations has been also compared with TMDs. According to the results, the optimized TLD has a better performance than TMD, and Jaya algorithm has a slightly better performance than the other algorithms.

Orientational Correlations in Active and Passive Nematic Defects.

We investigate the emergence of orientational order among +1/2 disclinations in active nematic liquid crystals. Using a combination of theoretical and experimental methods, we show that +1/2 disclinations have short-range antiferromagnetic alignment, as a consequence of the elastic torques originating from their polar structure. The presence of intermediate -1/2 disclinations, however, turns this interaction from antialigning to aligning at scales that are smaller than the typical distance between like-sign defects. No long-range orientational order is observed. Strikingly, these effects are insensitive to material properties and qualitatively similar to what is found for defects in passive nematic liquid crystals.

Thermal Analysis of a Forced Flow Diffusion Absorption Refrigeration System for Fishing-Boat Exhaust Waste Heat Utilization

Ammonia water absorption refrigeration systems are effective in utilizing fishing-boat exhaust waste heat for cryopreservation. However, the liquid level control and the use of a solution pump characterized by small flowrate and high-pressure head result in poor reliability in the traditional system. Besides, the system must necessarily be designed anti-swaying and anti-corrosion. This paper proposes a forced flow diffusion absorption refrigeration system, in which an inherently leak-free canned motor pump and an ejector are employed to provide the driving forces of the gas and liquid loops. The approximate single pressure operation allows for a simple passive liquid sealing control without throttling valves. The system adopts an integrated cooling strategy which allows the system to operate under swaying conditions, and the external seawater cooled heat exchanger avoids internal corrosion and leakage. The thermal analysis shows the system is valid to be operated under wide operating conditions, and the coupled gas and solution circulation ratios determined the performance of the novel system. There is an optimal ammonia mass fraction difference in the gas loop to obtain the optimal COP. The COP reaches 0.4 when the temperatures at the outlets of the generator, evaporator, absorber, and condenser are 160, −15, 35, and 35°C, respectively. The novel system provides a reliable absorption refrigeration system design for fishing-boat applications.

Dynamic-thermal modeling and motion analysis for deep-sea glider with passive buoyancy compensation liquid

The passive buoyancy compensation liquid (PBCL) has been widely used in underwater vehicles operating in deep-sea environments to reduce buoyancy loss caused by hull deformation and seawater density variation. The heat transfer process of PBCL is an important factor that affects the net buoyancy and motion performance of the deep-sea glider (DG), which was commonly neglected. A comprehensive dynamic-thermal model for Petrel-4000 deep-sea glider (PDG) with PBCL is established in this paper. A model which considers the heat transfer process is proposed to estimate the volume change of PBCL. These models are verified by comparing the numerical results with experimental data. The effect of the heat transfer process on the motion performance of PDG is fully analyzed by comparisons with those not considering heat transfer process. Then, the effect of PBCL distribution is discussed, which shows that the reasonable PBCL distribution can facilitate a more stable gliding attitude of PDG. Energy consumption analysis is carried out and the results indicate that the application of PBCL is beneficial for energy saving, especially under the lower power of the control system and measurement system. The results and conclusions would provide a valuable reference for the design and engineering applications of DG.

Paper-Based Carbon Dioxide Sensors: Past, Present, and Future Perspectives

Paper-based sensors are a new possible technology for fabricating easy, economical, portable, and expendable analytical devices for various application fields counting, diagnosis clinically, control of the quality of the food, and environmental monitoring. The distinctive characteristics of paper that enable the transport of the passive liquid and the affinity with chemicals/biochemical is the principal lead of employing paper as a sensing platform. Even if paper-based sensors are extremely favorable, they are quite abided due to undeniable constraints, namely, accuracy and sensitivity. Nevertheless, it is forecasted that in the coming times, with improvisation in the fabrication and analytical techniques, that there will be adding new and novel evolution in paper-based sensors. These sensors can meet the present-day intentions of being a cost-efficient and portable device besides contributing high sensitivity and selectivity and multiple analytes biasing. The present work is a review of paper-based sensors for sensing carbon dioxide.