Optimum Aperture Research Articles

Optical parameter design model of hemispherical laser retroreflector arrays for satellite laser ranging

A laser retroreflector array (LRA) with multiple retroreflectors is used to directionally reflect an incident laser beam and aims to enhance the received signal strength into laser ranging ground stations. A comprehensive mathematical equation of the received photons is established by modelling the LRA far field diffraction intensity (FFDI) and the satellite velocity aberration position. Based on this received photon model, a novel method on designing the dihedral angle offset and the aperture of retroreflectors is proposed, which maximizes the received photon under the minimal elevation angle of the ground station. Taking the hemispherical structure parameters of Chinese HY-2 satellite LRA and the specification parameters of the Shanghai Astronomical Observatory, the optimal aperture and the dihedral angle offset of the HY-2 laser retroreflectors are 17 mm and 1.6″, respectively. These two optimal optical parameters make the received photon under the elevation angle of 0° reach ∼0.9 count per laser shot. Until now, ∼851,400 successful observations have been successfully obtained by global ground stations since the first launch of HY-2 satellite series in 2011, which guarantees the high-precise orbit determination of HY-2 satellite series.

Optimization of the Electron Spectrometer Telescope geometry for the PRESET satellite through Monte Carlo simulation

The Electron Spectrometer Telescope (EST) aboard the PRESET satellite mission aims to measure the pitch angle distribution of 0.3–4 MeV electrons in the outer Van Allen belts. The PRESET satellite is planned to launch into a sun-synchronous low Earth orbit in Q2, 2026. We present comprehensive Monte Carlo simulations to optimize the design and response of the EST instrument. The EST consists of a stack of silicon strip detectors and a collimator to take pitch-angle dependent electron spectral measurements with a target angular resolution of 6° while rejecting the proton, heavy ion and gamma detection events. Various collimator designs and detector stacking configurations are investigated using the Geant4 code to deduce an optimal design and configuration. For validation of the Geant4 simulations, a benchmark test spectrometer was set up using a stack of four silicon detectors and a good agreement between the measured and simulated responses was found for a beta spectrum from a 90Sr/90Y source. The collimator design was optimized by adjusting total length, aperture size, number of view-ports and collimator materials. The optimum aperture size and the number of view-ports were determined by varying them and selecting the best cases that meet the angular resolution and the geometric factor requirements. Moreover, to address the under-utilization of the front position-sensitive detector encountered in a typical pin-hole collimator, two offset collimators with tilted axes were employed. Extensive simulations were carried out by varying the number of silicon detectors and the thickness of each detector to optimize the configuration of the silicon detector stack. An optimum thickness of the front detector was found to be 140 µm, which can minimize the perturbation counts caused by the proton detection events. For the other detectors, a stack of four 1.5 mm thick detectors was chosen to achieve a good sensitivity to low energy electrons at a tolerable complexity of the system. The angular response simulated for the optimum design of the EST showed a resolution of 5.5°, which is slightly better than the target resolution of 6°. The response matrices of the final design simulated for isotropic electron and proton fields showed a high geometric factor, which is expected to produce an average electron counting rate of 230 cps within the trapped region with a negligible contamination of the electron spectrum by protons except for a mild contamination by the 1.0–1.1 MeV protons.

Computer simulation of the effect of focusing X rays by means of refractive-diffractive lens

The features of focusing X rays using a refractive-diffractive lens (RDL), which is a system of two asymmetrically reflecting crystals with asymmetry factors, the product of which is equal to unity, and a refractive lens with a large focal length, are theoretically studied. Crystals make it possible to shorten the focal length of the lens by b2 times, where b is the asymmetry factor of the second crystal. A detailed numerical simulation of the effect of radiation focusing using the RDL has been performed. The universal computer program XRWP was used which is created to calculate the effects of coherent X-ray optics. Analytical formulas are obtained for the optimal aperture and radius of curvature of the lens, as well as for the width of the radiation spectrum that can be focused.

Impact of corner radius of the aperture on the accuracy of phase retrieval analysis in single-frame CDI for nanomaterials

Numerous efforts have been developed to advance the process of Ptychography, leading to the emergence of a phenomenon known as single-frame Coherent X-ray Diffraction Imaging (CDI). It represents an advanced form of Ptychography in which a well-defined coherent X-ray beam is directed onto the sample to generate a diffraction image that includes intensity information but lacks phase details. However, phase retrieval in single-frame CDI faces challenges like overlapping loss, inadequate samples, or phase ambiguity due to the characteristics of this method. The optimising effort has been conducted in the form of aperture implementation to address these problems, particularly in the iterative phase retrieval domain. This study explores non-point symmetrical apertures, specifically triangles, to enhance image reconstruction quality in iterative phase retrieval. We developed a simulation methodology to explore the impact of corner radius on the apertures in performing single-frame CDI. Our simulator generates diffraction images for each shape, which are processed through iterative algorithms and deep learning to reconstruct images. The effectiveness of each shape is assessed by visualising the loss function results, providing insights into optimal aperture designs for diffraction imaging, and contributing to the resolution of phase retrieval challenges in single-frame CDI.

Development of single layer osmotic controlled release tablet for low soluble drug: Single Core Osmotic Pump (SCOP)

A novel Single Core Osmotic Pump (SCOP) pill has been created to administer high doses of the low solubility medication Rifaximin using osmosis. The formulations were evaluated using six comparative parameters: Q24 (total release after 24 hours), Q12 (total release after 12 hours), TL (lag time), RSQzero12 (R square of the zero-order equation for drug release in 12 hours), RR12 (in vitro release rate for 12 hours), and T80% (time required to deliver 80% of the drug). The drug release profile from osmotic devices shows that the choice of polymer and its concentration in the core formulation can significantly impact the release of the drug. Augmenting the osmogent quantity to an optimal level resulted in a substantial enhancement of Q12 and a notable improvement in the zero-order release pattern of rifaximin. In order to improve the bioavailability of the core formulation, an additive called citric acid was included. Citric acid has several properties that contribute to this enhancement, such as increased solubility of the active ingredient, the creation of a difference in osmotic pressure, regulation of the flow of the active ingredient, and making the composition containing the active ingredient more water-loving. Consequently, TL and T80% experienced a decline, whereas Q12 and RR12 saw a rise. The concentration of PEG 4000 in the semipermeable membrane of the SCOP was found to have a significant impact on TL, T80%, Q12, Q24, and RR12. Specifically, increasing the concentration of PEG 4000 led to a decrease in TL and T80%, while increasing Q12, Q24, and RR12. The optimal aperture diameter for achieving a zero-order release pattern was found to be 850 μm. This study also demonstrated that optimizing the thickness of SPM is crucial for achieving zero order kinetics. The invented SCOP technology has the potential to create a single layer osmotic controlled release tablet of a water insoluble medication with a high dosage.

New method for landslide susceptibility evaluation in alpine valley regions that considers the suitability of InSAR monitoring and introduces deformation rate grading

ABSTRACT Incorporating Interferometric Synthetic Aperture Radar (InSAR) data sources into the landslide susceptibility evaluation process has yielded favorable outcomes in some studies. However, there are fewer analyses of the applicability of InSAR data monitoring, and a framework of accurate and effective grading criteria needs to be developed. To overcome these limitations, this study presents a novel and precise approach for landslide susceptibility assessment in alpine valley regions. This method incorporates the suitability of InSAR monitoring and introduces a grading system based on deformation rates, enhancing accuracy and efficiency. Taking the Dongchuan district, the most typical high mountain valley area in southwest China, as the research object, the SAR is quantitatively simulated and analyzed in this study using the improved R-index shadow layover method. Then, the optimal Synthetic Aperture Radar (SAR) monitoring scheme is derived, calculate deformation rates using LiCSBA (small baseline subset with the automated sentinel-1 InSAR processor) technology, and accurately establish the extent of landslide hazards (including potential landslides) by incorporating high-resolution images. The criteria for grading susceptibility within the landslide hazard range are based on deformation rates. Evaluation factors for corresponding grid cells are obtained. The best evaluation factors are selected using covariance diagnosis and gray correlation analysis. The landslide susceptibility model is developed utilizing the Particle Swarm Optimization-Back Propagation (PSO-BP) algorithm. It includes evaluation techniques for regions without deformation rates. The study findings demonstrate that: (i) Analyzing SAR suitability in alpine and canyon areas is crucial. Complementary monitoring with SAR lift tracks may only sometimes resolve geometric distortion issues in all these regions. (ii) The InSAR deformation rate can be an essential evaluation factor for landslide susceptibility evaluation. (iii) The proposed method effectively addresses low coherence challenges in certain alpine valley regions, where grading based on deformation rate is complex. The landslide susceptibility evaluation model is validated using performance evaluation indexes (Mean Absolute Error (MAE), Root Mean Square Error (RMSE), Mean Absolute Percentage Error (MAPE), and R-Square (R2)), confirming its reliability and effectiveness. (iv) The proposed method improves the grading accuracy by 37.84 ~ 60.91%. Overall, our proposed new landslide susceptibility method brings a new way of evaluating landslide susceptibility in alpine valley regions.

Research on Damping Hole Optimization of Hydro-Pneumatic Suspension for Mining Trucks under Variable Load Conditions

The hydro-pneumatic suspension, known for enhancing vehicle ride comfort and stability, finds widespread use in engineering vehicles. Presently, the majority of mining trucks employ hydro-pneumatic suspension with a fixed damping hole, underscoring the critical importance of selecting appropriate damping hole parameters. Initially, an equilibrium mathematical model of the ¼ hydro-pneumatic suspension is established, and the influencing factors of the damping characteristics are analyzed. Subsequently, the simulation model and experimental bench for the hydro-pneumatic suspension are constructed. Sinusoidal signals with different frequencies and amplitudes serve as the excitation signals to analyze the variation trend of the force on the rod with displacement changes. The simulation and experimental results demonstrate a high degree of consistency, validating the rationality and validity of the simulation model. Building upon this foundation, various damping apertures are then selected to study the damping characteristics of the hydro-pneumatic suspension. The research indicates that as the damping aperture increases, the setting time of the hydro-pneumatic suspension system after excitation extends, accompanied by a decrease in the acceleration overshoot. As a result, a comprehensive evaluation index is developed, considering various factors, such as different weight setting times and peak longitudinal accelerations to assess the ride comfort of the suspension. This approach is then employed to determine the optimal damping aperture under both full-load and no-load conditions. The findings of this research offer valuable insights for the development of adaptive variable damping hydraulic suspensions, especially under variable load conditions.

Influence of Grid Aperture Ratio on Electron Transmittance and Electron Beam Spot Size in Field Emission Processes of Carbon Nanotubes

Field emission is an important work mode for electron sources, and carbon nanotubes (CNTs) have been extensively studied for their good emission properties. It is well known that the parameters of the grid deeply influence the field emission performance of CNTs, a relationship that requires further elucidation. Therefore, in this study, the relationship between the grid aperture ratio and electron transmittance was studied through simulations and experiments. This study’s results indicate that the electron transmittance improved as the grid aperture ratio increased. Meanwhile, electron beam spot simulations and imaging experiments indicate that an increased grid aperture ratio will expand the cathode electron divergence, leading to a larger electron beam spot size. These results demonstrate that there is a trade-off in maintaining the grid aperture ratio between high electron transmittance and relatively small electron beam spot size, and the optimum grid aperture ratio is between 75% and 85%. These results will provide a reference for the design and optimization of X-ray tubes and other electron sources.

Harnessing solar power in industry: Heuristic optimisation design and transient thermal modelling of parabolic trough solar collector networks

This study presents the development of a transient model for designing and optimising parabolic trough solar thermal plants for industrial processes. The model is validated against published experimental data and other models from the literature. A heuristic optimization methodology based on Particle Swarm Optimization (PSO) to maximise the Present Value of the Life Cycle Energy Savings (PVLCES) is employed. This methodology is applied to three case studies. The results highlight the versatility of PTC (parabolic trough collector) technology in handling a wide range of temperatures. Additionally, the study reveals the optimal PTC aperture width dimensions that maximise the capture of solar thermal energy while increasing the solar fraction. Specifically: For low-temperature processes, the optimum aperture width is 5.0 m; in medium-temperature processes, the optimum aperture width increases to 5.5 m; for high-temperature applications, the optimal value is 5.8 m. Finally, the optimised networks achieve the following heat load-to-area ratios: Low-temperature applications: 0.57 kW/m²; medium-temperature applications: 0.58 kW/m²; high-temperature applications: 0.6 kW/m².

Phycoremediation Potential of Salt-Tolerant Microalgal Species: Motion, Metabolic Characteristics, and Their Application for Saline-Alkali Soil Improvement in Eco-Farms.

Microalgae have great potential for remediating salt-affected soil. In this study, the microalgae species Coelastrella sp. SDEC-28, Dunaliella salina SDEC-36, and Spirulina subsalsa FACHB-351 were investigated for their potential to rehabilitate salt-affected soils. Nylon screens with optimal aperture sizes and layer numbers were identified to efficiently intercept and harvest biomass, suggesting a correlation between underflow capability and the tough cell walls, strong motility, and intertwining characteristics of the algae. Our investigations proved the feasibility of incorporating monosodium glutamate residue (MSGR) into soil extracts at dilution ratios of 1/200, 1/2000, and 1/500 to serve as the optimal medium for the three microalgae species, respectively. After one growth period of these three species, the electrical conductivities of the media decreased by 0.21, 1.18, and 1.78 mS/cm, respectively, and the pH remained stable at 7.7, 8.6, and 8.4. The hypotheses that microalgae can remediate soil and return profits have been verified through theoretical calculations, demonstrating the potential of employing specific microalgal strains to enhance soil conditions in eco-farms, thereby broadening the range of crops that can be cultivated, including those that are intolerant to saline-alkali environments.

Pinhole camera for electron beam size diagnostic at storage ring with an ultralow emittance

In this work, we propose to use a pinhole camera at high photon energies, specifically 200–300 keV, to measure ultra-small electron beam size by means of bending magnet radiation. We show that there is a sufficient photon flux at the detector position. Our theoretical analysis includes an examination of the applicability of the van Cittert-Zernike theorem for the bending magnet radiation generated by an ultralow emittance electron beam and a detailed analysis of the imaging properties of rectangular pinhole cameras. This led us to practical, universal formulas. We identify the optimal aperture size and resolution of the camera in the given geometry. The theoretical findings are further substantiated by wavefront propagation numerical simulations of partially coherent radiation. This study serves both as a practical guide for optical engineering and an educational resource for explaining the imaging properties of pinhole cameras. Published by the American Physical Society 2024

Enhancing Heat Transfer: Unraveling the Dynamics of Mixed Convection in a Vertical Porous Cavity

Mixed convection inside a vertical square porous cavity is investigated numerically, with special attention given to left-side heating. In the study, the importance of the problem, methods used, main results, conclusions, and novelty of the work are discussed. The Brinkmann-Forchheimer-Darcy coupled momentum equations and the Local Thermal Equilibrium energy (LTE) equation are solved using the finite volume technique. Several elemental parameters are investigated, including Reynolds number (50 × Re × 300), Darcy number (0.01 × Da × 100), Richardson number (0 × Ri × 30), and porosity (0.5 × ε ≥ 0.95). The thermal conductivity ratio of solid to liquid was (1<Kr<105), and the inlet port width between (0.05<d/H<0.3). Results show that Nusselt number increases with Reynolds number, Richardson number, and pore thermal conductivity. With increasing porosity, an inverse relationship was observed. Nusselt number was maximized by finding the optimal inlet aperture size (d/H = 0.25). It provides valuable insights into how different parameters affect mixed convection in vertical square porous cavities. Heat transfer processes in porous media are improved by these results. This work goes beyond previous efforts in the literature in exploring a wide parameter space and determining the optimal inlet aperture size.

Investigating effects of tire geo-scrap reinforcement on shear strength characteristics of railway ballast using large-scale direct shear test

ABSTRACT The utilization of geogrids used to ballast reinforcement has been widely investigated by researchers in the technical literature. This technique aims to enhance the load-bearing capacity of ballast while mitigating its degradation by minimizing breakage and settlement. This research proposes a novel approach to enhancing ballast shear behaviour in a large-scale direct shear test through the use of geogrids composed of waste tire strips, referred to as ‘geo-scraps’. In this study, the geo-scrap performance on ballast shear reinforcing was investigated to find the best laying depth in the ballast layer and the optimum aperture size of grids. To this aim, the geo-scraps were positioned at four different depths of the ballast (6, 12, 18, and 24 cm) and then the shear tests were carried out on geo-scraps with three different aperture sizes (5 cm x 5 cm, 10 cm x 10 cm, and 25 cm x 25 cm). All the large-scale shear tests were conducted under normal stresses of 50, 100, and 150 kPa. The findings of laboratory tests indicate that the 5 cm x 5 cm aperture positioned 12 cm from the bottom of the box yields the most desirable results for the ballast in terms of enhancing shear strength, augmenting the internal friction angle, and reducing the dilatancy angle. Compared to the non-reinforced (NR) state, the shear strength and internal friction angle experienced respective increases of 20% and 7%, while the dilatancy angle decreased by 30%. These outcomes show that the geo-scraps appropriately reinforced the ballast in terms of shear behaviour.

Fabrication of quartz microlenses using laser ablation

Various quartz microlenses were fabricated in two stages with two lasers. A fiber laser at 1.06 µm was employed for the laser ablation, while a CO2 laser at 10.6 µm was used for direct laser writing (DLW). The experimental data demonstrate the formation of spherical, cylindrical microlenses and microlens array (MLA) with an optimum numerical aperture (NA) of 0.55. Theoretical calculations and simulation were conducted to estimate the temperature at the quartz surface during ablation and simulation of the reshaping. A temperature of 2500 K is achieved in the ablation, and 2015 K was established during the reshaping. The ablation depth is 280 µm, the diameter is 150 µm, and the heat affected zone (HAZ) is approximately 1345 µm after 1 s. Due to the controllable laser micromachining, optoelectronics and biological imaging are viable applications for MLAs.

Optimized Integer Aperture Bootstrapping for High-Integrity CDGNSS Applications

Integer Aperture Bootstrapping (IAB) is a crucial method for testing ambiguity acceptance in carrier-phase differential global navigation satellite system (CDGNSS) positioning. It has the advantage that integrity parameters, such as the failure rate, can be analytically calculated, which is essential in safety-of-life applications. Although the IAB methods have been extensively studied, their threshold-determining method is still not well explained, theoretically. In this study, a new method, named Analytical Integer Aperture Bootstrapping (AIAB), is theoretically derived to determine the optimal IAB threshold. AIAB is novel in that: (1) a precise and easy-to-compute expression has been developed to describe the relationship between the IAB threshold and the failure rate, (2) an analytical function model has been derived from the expression to determine the IAB threshold; moreover, the function model is simplified, and (3) a data-constraint approach has been proposed to reduce the complexity of IAB. In the global CDGNSS simulations, AIAB is shown to outperform the existing IAB methods under both strong and weak models, particularly at low fix rates, which are 23% to 40% higher than the basic IAB method. The Monte Carlo simulation results show that AIAB can obtain almost theoretically the same performance as Optimal Integer Aperture (OIA).

Analytical Modeling of a Slit Collimator and Optimization for Small Animal Imaging Applications

Purpose: The collimator design and optimization are essential in small animal molecular imaging for preclinical studies. In this study, a mathematical model was derived and used to optimize the slit collimator for small animal imaging applications. Materials and Methods: The geometric efficiency was formulated as a source-to-detector distance for a certain amount of the collimator resolution ( ). The first-order derivative of the derived formula gives the optimized parameters. The detector performance was modeled in terms of intrinsic resolution . Furthermore, the edge penetration effect was considered using the validated model. Results: Optimum source-to-detector distance was found as . For an ideal detector, optimal , geometric efficiency and slit aperture width were found as , and , respectively. Where and are the source-to-collimator distance and detector length, respectively. For the fixed resolution of 1.0 mm, the sensitivity for different source-to-collimator distances of 50.0, 100.0, and 150.0 mm was calculated as , , and , respectively. In addition, for a sub-millimeter resolution of 0.5 mm at 15.0, 30.0, and 50.0 mm, the geometric efficiency was calculated as, , , and . For a typical source-to-collimator distance (15.0 mm), the optimal geometric efficiencies are , , , , and for the resolutions of 0.25, 0.50, 1.0, 1.5, and 2.0 mm, respectively. Conclusion: Based on the analytic model predictions, the performance characteristics of the slit collimator in terms of geometric efficiency and resolution were extracted. The importance of the proposed model lies both in its speed and ease of application.

Unlocking the potential of phosphogypsum waste: Unified synthesis of functional metal-organic frameworks and zeolite via a sustainable valorization route

Phosphogypsum (PG) is one of the hazardous wastes generated during phosphate fertilizers production. Valorizing PG into value-added materials is needed to overcome the environmental threat of accumulating PG stockpiles. The primary chemical constituents of PG are CaSO4·2H2O, SiO2, Al2O3, P2O5, and trace metals. Herein, we employed unified strategic synthesis method to transform the main components of PG into two classes of functional porous materials in subsequent steps. The alumina and silica components were isolated to fabricate cancrinite zeolite (CAN) while the residual calcium was directed to grow Ca-based metal–organic frameworks (Ca-MOFs) in the subsequent step. The resulting zeolite with a Si/Al ratio of ∼2.2 showed enhanced CO2 capture property, which, in many respects, is better than those achieved by similar frameworks from other precursors. The unveiled MOF synthesis approach was proven to be adaptable, allowing the preparation of different Ca-MOFs from organic linkers of diverse connectivity, namely Ca-BDC, Ca-BTC, and Ca-TCPB (SBMOF-2), using the linear ditopic benzene dicarboxylate, the tritopic benzene tricarboxylate, and tetracarboxylate-based linkers, respectively. The successful assembly of the porous materials was confirmed using various characterization techniques, including XRD, SEM-EDX, FTIR, and TGA-MS. The porosity of the materials was also probed using N2 at 77 K, CO2 at different temperatures, and H2O at 298 K sorption analyses. The Ca-BTC MOF with the optimal pore aperture size (∼3.4 Å) shows a potential for water/alcohol separation with a steep and fast moisture adsorption profile and negligible alcohol uptake. The synthetic transformation approach presented in this work represents the first example of a valorization route to form extended porous structures from PG waste.

Optimizing geometrical parameters of coherent beam combining in the near and far-field distance

Determining the characteristics of the laser array to improve the performance of a laser system based on coherent beam combination (CBC) has continuously garnered interest. To this end, the parameters of the Gaussian beam waist, array shape, and distance between adjacent beams were studied and numerically investigated in this study. Consequently, the combined beam quality was compared for hexagonal, circular, and square arrays. The observing plane’s location was fixed at 10 km and varied from 0.25 to 10 km to investigate the effect of beam waist on combined beam quality in two modes (near and far field) using the power in the 5 cm bucket metric (PIB5cm). Furthermore, the average PIB5cm was investigated to determine all observing plane distances. The simulation results in two states of fixed and variable observing plane distances demonstrated that the hexagonal array has an advantage in attaining PIB5cm and higher combined beam quality. In addition, the quality of the combined beam degrades as the space between the beams increases. Moreover, the optimal beam waist and aperture diameter are independent of the array geometry and the vacancy between adjacent beams.

Insight into the Isoreticularity of Li-MOFs for the Design of Low-Density Solid and Quasi-Solid Electrolytes.

Isoreticularity in metal organic frameworks (MOFs) allows the design of the framework structure and tailoring the pore aperture at the molecular level. The optimal pore volume, long-range order of framework expansion, and crystallite size (grain size) could enable improving Li-ion conduction, thereby providing a unique opportunity to design high-performance solid and quasi-solid electrolytes. However, definitive understanding of the pore aperture, framework expansion, and crystallite size on the Li-ion conduction and its mechanism in MOFs remains at the exploratory stage. Among the different MOF subfamilies, Li-MOFs created by the isoreticular framework expansion using dicarboxylates of benzene, naphthalene, and biphenyl building blocks emerge as low-density porous solids with exceptional thermal stability to study the solid-state Li+ transport mechanisms. Herein, we report the subtle effect of the isoreticularity in Li-MOFs on the performance of solid and quasi-solid-state Li+ conduction, providing new insight into Li+ transport mechanisms in MOFs for the first time. Our experimental and computational results show that the reticular design on an isostructural extended framework structure with the optimal pore aperture and crystallite size can influence the Li+ conductivity, exhibiting comparable ionic conductivities to solid polymer electrolytes at room temperature. Aligning with the computational studies, our experimental absorption spectral traces of solid electrolytes prepared by encapsulating lithium salt (LiClO4) and the plasticizer (ethylene carbonate) with Li-MOFs confirm the participation of the free and bound states of Li+ in a pore filling-driven ion conduction mechanism. We postulate that porous channels of Li-MOFs aid free Li+ to move through the pores via a vehicle-type mechanism, in which the pore-filled plasticizer acts as a carrier for mobile Li+ while the framework's functional sites transport the bound state of Li+ via an ion hopping mechanism from one crystallite site to another. Our computational studies performed on the Li+ conduction pathway validated the postulated pore filling mechanism and confirmed the involvement of bridging complexes, formed by binding Li+ onto the framework's functional sites as well as to the pore-filled ethylene carbonates. The Li+ diffusion energy barrier profiles along with the respective conformational changes during the diffusion of Li+ in solid electrolytes prepared from Li-BDC MOF and Li-NDC MOF strongly support the cooperative movement of Li+ ions via ion hopping along the framework's edges and vehicle-type transfer, involving the pore-filled plasticizer. Our findings suggest that cooperative function of the optimal pore volume, framework expansion, and crystallite size play a unique role in Li-ion conduction, thereby providing design guidelines for the low-density solid and quasi-solid electrolytes.

Rapid synthesis of ultra-microporous metal-organic framework tubular Ni-LAP membranes for H2 separation by linker salt method

Recently, the development of pillar-layered metal-organic frameworks (MOFs) is receiving more and more attention because of their pore surface chemistry tunability and designability. In this work, we firstly synthesized various sizes of high-quality Ni-LAP [Ni2(L-asp)2(pz)] (L-asp = l-aspartic acid, pz = pyrazine) crystals key for secondary growth by manipulating the crystal thermal dynamics and kinetics of Ni-LAP synthesis solution simply through choosing the Ni(OAc)2 as metal source and pretreatment at 40 °C, followed by the fabrication of defect-free Ni-LAP membranes as a model in a short time of 4 h using the linker salt method. It is found the pretreatment of Ni(OAc)2 precursor solution at 40 °C with continuous stirring for 6 h can effectively promote deprotonation to form 250 nm crystals. The linker salt method enables a greener and more rapid synthesis of Ni-LAP membranes, with continuous and compact Ni-LAP membranes, where soluble metal precursors and organic linking salts provide the synthesis solution a higher degree of supersaturation, both of which play an important role in the rapid preparation of Ni-LAP membranes. The preparation parameters of the Ni-LAP membranes were investigated in detail, and the results from the Ni-LAP membrane gas separation performance showed that the preferential (111) orientation membrane (M9) exhibited the best H2/CO2 separation performance with separation factor of 23.8 and H2 permeance of 2.11 × 10−7 mol m−2 s−1 Pa−1 compared to the preferential (002) orientations (M3), which may attributed to the preferential (111) orientation being at an angle to the optimal a-axis aperture perpendicular to the support thereby reducing the mass transfer resistance. Furthermore, the generation of corrosive nitric acid during the preparation process can be greatly reduced and replaced by eco-friendly potassium nitrate. The superiority of the pore structure and the remarkable stability of these MOF membranes show the potential for H2 purification. Moreover, our preparation route demonstrates the universality of preparing other isomorphs, such as Ni-LAB and Co-LAP membranes.