Theoretical Simulation Research Articles

Economical and rapid mechanochemical synthesis of porous organic adsorbents with high hydrophilicity for ultra-fast removal of organic micro-pollutants from water

Various porous adsorbent materials have shown excellent adsorption performance for the removal of organic micro-pollutants in water. However, the practical application was hindered by the high cost or slow adsorption kinetics for most of porous adsorbents. Therefore, it is of great significance to develop economic adsorbent materials with characteristic like low-cost, easier preparation method, excellent adsorption kinetics etc.Herein, based on the Friedel-Crafts alkylation reaction, we reported three novel hydrophilic organic porous adsorbent frameworks (PAF-210, PAF-211 and PAF-212) with high Brunauer-Emmet-Teller (BET) surface area (956 ∼ 1384 m2/g) for phenolic micro-pollutants (bisphenol A (BPA), 2,4-dichlorophenol (2,4-DCP) and 2-naphthol (2-NO)) adsorption in water, which were prepared by using cheap trimethyl orthoformate (TMOF) as crosslinker and one-step simple ball milling synthetic method under room temperature within 15 min. Rich oxygen content promotes the resulting polymers to possess excellent hydrophilicity and wettability through water vapor adsorption and water contact angle analysis. The excellent hydrophilicity and proper porous properties made the resulting frameworks suitable as porous organic adsorbents to rapidly remove organic phenolic micro-pollutants from water. Among the resulting polymers, the PAF-210 exhibited ultra-fast adsorption (>94.0 % within 5 s), ultra-rapid adsorption kinetics with pseudo-second-order rate constants (K2, up to 7.72g/mg min−1 for 2,4-DCP), high pollutant adsorption capacity (up to 867.03 mg g−1 for BPA) and excellent recyclability (10 cycles with slight loss in adsorption capacity) through systematically characterization. The adsorption performances of PAF-210 are much better than these of the commercial activated carbons and β-cyclodextrin-based porous adsorbents (K2 = 1.50g/mg min−1 for P-CDP) etc. The favorable hydrophilicity, surface wettability, and adsorption performance of PAF-210 were significantly better than the comparative material constructed by using benzene and formaldehyde dimethyl acetal (FDA) through conventional thermal synthetic method, which is a very classic synthesis strategy in the field of porous materials. More importantly, the PAF-210 exhibited relatively superior adsorption performance on BPA, and it still presented excellent adsorption performance (removal efficiency ≥ 96.8 % within 5 s after 10 cycles) even at the safe range of BPA quantified in drinking water (BPA≤10 μg L−1, Standards for drinking water quality, GB5749-2022, China). XPS analysis and theoretical simulations proved that the excellent adsorption performance and ultra-fast adsorption rate stem from interactions including π-π interactions, hydrogen bonding and van der Waals interactions between PAF-210 and micro-pollutants.

A space-borne ultra-stable laser system with an excellent long-term frequency stability for gravitational wave detection

Abstract Ultra-stable lasers are pivotal in various scientific applications, notably in space gravitational wave detection projects. We develop a space-borne ultra-stable laser system based on a home-made non-planar ring oscillator (NPRO) laser and an ultra-stable cavity laser stabilization system. The ultra-stable cavity is a vertically mounted 8 cm long cavity, with tunable zero-crossing temperature and low vibrational sensitivity. To make a cavity with any standard grade ultra-low expansion glass (ULE) material, and tune the zero-crossing temperature to the satellite platform temperature, we design three ultra-stable cavities with different configurations to unambiguously explore their thermal properties. The measurement results meet the design goals well, and the zero-crossing temperature of the cavity can be tuned from − 19 ∘ C to 16.0 °C. We measure the temperature fluctuation noise through modulation experiment, and it agrees well with the theoretical simulations. The vibrational sensitivities in three directions are measured to be around 10−11 /g–10−10 /g. The total weight of the system is 14.0 kg, with a volume of about 18 L, and the power dissipation of the electrical system is 18.6 W. Finally, the prototype of the space-borne laser shows a frequency instability of 9.5 × 10 − 16 at 0.2 s, and the frequency noise is measured to be 3.6 Hz/Hz1/2 at 6 mHz over three months, satisfying the mission targets of all current space gravitational wave detection programs.

Programmable curvilinear self‐propelling of droplets without preset channels

AbstractCurvilinear self‐propelling of droplets has attracted great interest in the past few decades due to their irreplaceable roles in many areas. Conventional understanding is that a droplet moves only along a preset channel formed by morphology or chemical components. Achieving programmable curvilinear droplet motion independent of a preset channel remains greatly challenging. Here, we report a programmable curvilinear self‐propelling of droplets (circle, divergence, and convergence) based on the collaboration of the curvilinear wetting gradient and the Leidenfrost effect. This design achieves motion trajectory in a well‐controlled manner as well as high velocity and long distance of droplet transport independent of the preset channel. Moreover, the motion behaviors of droplets could be predicted accurately by theoretic simulation. We envision that our unique design could manifest extensive practical applications in fluidic devices, liquid transport, and heat transfer systems.

Effect of a uniform magnetic field on the nonlinear instability of double cylindrical interfaces concerning three magnetic liquids

The present manuscript relates to the movement of three immersed viscous magnetic liquids in porous media that are positioned between three concentric cylindrical interfaces. Every cylindrical layer has an axial extension that extends in both vertical directions to infinity. Moreover, the pressure gradients are the driving force behind the uniform motion of all fluids in a similar upward motion at varying velocities. Permanent magnetic fields are tangentially oriented exert stress on the system. The computations are rendered simpler by applying the viscous potential theory. The Maxwell equations are utilized for the magnetic field, while the Brinkman-Darcy equations define the fluid mobility. Moreover, the rise of the disturbance and the subsequent extraction of fuel from the tiny cracks of the reservoir stone can be managed through the implementation of engineering techniques such as electromagnetic field impacts and oil extraction engineering. Typically, the nonlinear strategy involves incorporating the applicable nonlinear boundary conditions and analyzing the linearized equations of motion. This research offers a framework for verifying theoretical models and simulations based on experimental observations. The inclusion of a homogeneous magnetic field introduces complexity to the system, rendering it a suitable candidate for validating and improving models in the field Magneto hydrodynamics. The originality of the problem lies in the dual nonlinear stability of cylindrical interfaces when subjected to uniform magnetic field. Accordingly, two nonlinear characteristic differential equations controlling the surface displacements are produced. The nonlinear stability prerequisite is met by applying the matrix concept and the multiple scale technique in conjunction with a theoretical analysis of stability. Additionally, the Routh-Hrutwitz criterion is encompassed to judge the stability cofiguration. A detailed examination of the associated nonlinear stability requirements is showed. Meanwhile, the estimated limited solutions of perturbed surfaces are achieved. For the cylindrical middle layer, it is found that the outer cylindrical interface has a more stabilizing effect than the inner one. The approximate solutions for displacements at the interface are calculated. The influence of Weber numeral of the problem on the stability profile is investigated.

Heteroatom-Doped Defects Anchoring Nano-Pt for High-Stability and Low-Humidity Proton Exchange Membrane Fuel Cell.

To meet the ever-increasing demand of proton exchange membrane fuel cell (PEMFC), it is necessary to carry out structure optimization for low-cost and high-stability oxygen reduction reaction (ORR) catalysts. Herein, a zeolitic imidazolate framework (ZIF)-derived carbon material with a mass of heteroatoms and defects is developed and serves as advanced support for nano-Pt-based ORR catalysts. This unique structure enhances the interaction between nano-Pt and support, leading to higher ORR intrinsic activity. During fuel cell applications, it demonstrates impressive water-retaining capacity and electrochemical stability. Under H2-O2 supply without cathode humidification, this catalyst achieves high mass activity of 0.475 A mgPt -1, with only 7.4% attenuation in maximum power density after 20 000 cycles of accelerated durability test, highlighting its remarkable potential for fuel cell applications. Physicochemical characterization and theoretical simulation reveal the crucial anchoring effect of heteroatom-doped defects to nano-Pt, providing valuable insights for further ORR catalyst design and PEMFC applications.

Selective Synthesis of Organonitrogen Compounds via Electrochemical C-N Coupling on Atomically Dispersed Catalysts.

The C-N coupling reaction demonstrates broad application in the fabrication of a wide range of high value-added organonitrogen molecules including fertilizers (e.g., urea), chemical feedstocks (e.g., amines, amides), and biomolecules (e.g., amino acids). The electrocatalytic C-N coupling pathways from waste resources like CO2, NO3-, or NO2- under mild conditions offer sustainable alternatives to the energy-intensive thermochemical processes. However, the complex multistep reaction routes and competing side reactions lead to significant challenges regarding low yield and poor selectivity toward large-scale practical production of target molecules. Among diverse catalyst systems that have been developed for electrochemical C-N coupling reactions, the atomically dispersed catalysts with well-defined active sites provide an ideal model platform for fundamental mechanism elucidation. More importantly, the intersite synergy between the active sites permits the enhanced reaction efficiency and selectivity toward target products. In this Review, we systematically assess the dominant reaction pathways of electrocatalytic C-N coupling reactions toward various products including urea, amines, amides, amino acids, and oximes. To guide the rational design of atomically dispersed catalysts, we identify four key stages in the overall reaction process and critically discuss the corresponding catalyst design principles, namely, retaining NOx/COx reactants on the catalyst surface, regulating the evolution pathway of N-/C- intermediates, promoting C-N coupling, and facilitating final hydrogenation steps. In addition, the advanced and effective theoretical simulation and characterization technologies are discussed. Finally, a series of remaining challenges and valuable future prospects are presented to advance rational catalyst design toward selective electrocatalytic synthesis of organonitrogen molecules.

Modulating Solvation Shell with Acrylamide Electrolyte Additives for Reversible Zn Anodes.

The reconsideration of aqueous zinc-ion batteries (ZIBs) has been motivated by the attractive zinc metal, which stands out for its high theoretical capacity and cost efficiency. Nonetheless, detrimental side reactions triggered by the remarkable reactivity of H2O molecules and rampant dendrite growth significantly compromise the stability of the zinc metal anode. Herein, a novel approach was proposed by leveraging the unique properties of acrylamide (AM) molecules to increase the driving force for nucleation and parasitic reactions. Combined with experimental data and theoretical simulations, it is demonstrated that the incorporation of AM additive can reconstruct the solvation shell around Zn2+ and reduce the number of active H2O molecules, thereby effectively reducing the H2O molecule decomposition. Consequently, the Zn//Zn symmetric batteries with AM-containing ZnSO4 electrolytes can attain excellent long-term performances over 2000 h at 1 mA cm-2 and nearly 500 h at 10 mA cm-2. The Zn//VO2 full batteries still display improved cycling performances and a high initial discharging capacity of 227 mA h g-1 at 3 A g-1 compared to the ZnSO4 electrolyte. This electrolyte optimization strategy offers new insights for achieving long-term ZIBs and advances the progress of ZIBs in energy storage.

Polarization Analysis of Vertically Etched Lithium Niobate-on-Insulator (LNOI) Devices

LNOI devices have emerged as prominent contributors to photonic integrated circuits (PICs), benefiting from their outstanding performance in electro-optics, acousto-optics, nonlinear optics, etc. Due to the physical properties and current etching technologies of LiNbO3, slanted sidewalls are typically formed in LNOI waveguides, causing polarization-related mode hybridization and crosstalk. Despite the low losses achieved with fabrication advancements in LNOI, such mode hybridization and crosstalk still significantly limit the device performance by introducing polarization-related losses. In this paper, we propose a vertically etched LNOI construction. By improving the geometrical symmetry in the waveguides, vertical sidewalls could adequately mitigate mode hybridization in common waveguide cross sections. Taking tapers and bends as representatives of PIC components, we then conducted theoretical modeling and simulations, which showed that vertical etching effectively exempts devices from polarization-related mode crosstalk. This not only improves the polarization purity and input mode transmittance but also enables lower polarization-related losses within more compact structures. As a demonstration of fabrication feasibility, we innovatively proposed a two-step fabrication technique, and successfully fabricated waveguides with vertical sidewalls. Such vertical etching technology facilitates the development of next-generation high-speed modulators, nonlinear optical devices, and other advanced photonic devices with lower losses and a smaller footprint, driving further innovations in both academic research and industrial applications.

Analysis and Design of an Airborne-Dangled Monopole-Antenna Symmetric Remote-Sensing Radiation Source for Airport Runway Monitoring

Traditional methods for monitoring the foundation settlement of airport runways predominantly employ equipment such as leveling instruments, total stations, layered settlement instruments, magnetic ring settlement instruments, ground-penetrating radar (GPR), and synthetic aperture radar. These methods suffer from low automation levels, are time-consuming, labor-intensive, and can significantly disrupt airport operations. An alternative electromagnetic detection technique, Controlled Source Audio-Frequency Magnetotellurics (CSAMT), offers deep-depth detection capabilities. However, CSAMT faces significant challenges, particularly in generating high signal-to-noise ratio (SNR) signals in the far-field region (FfR). Traditional CSAMT utilizes grounded horizontal dipoles (GHDs), which radiate symmetric beams. Due to the low directivity of GHDs, only a small fraction of the radiated energy is effectively utilized in FfR observations. Enhancing the SNR in FfR typically requires either reducing the transceiving distance or increasing the transmitting power, both of which introduce substantial complications. This paper proposes an airborne-dangled monopole-antenna symmetric remote-sensing radiation source for airport runway monitoring, which replaces the conventional GHD. The analytical, simulation, and experimental verification results indicate that the energy required by the airborne-dangled symmetric source to generate the same electric field amplitude in the FfR is only one-third of that needed by traditional CSAMT. This results in significant energy savings and reduced emissions, underscoring the advantages of the airborne-dangled monopole-antenna symmetric source in enhancing energy efficiency for CSAMT. The theoretical analysis, simulations, and experimental results consistently verify the validity and efficacy of the proposed airborne-dangled monopole-antenna symmetric remote-sensing radiation source in CSAMT. This innovative approach holds substantial promise for airport runway monitoring, offering a more efficient and less intrusive solution compared to traditional methods.

Highly reversible Zn anode by guiding uniform Zn deposition through LiF protective layer

Deep-seated issues such as ineluctable dendrite deposition and parasitic reaction of Zn anode pose a major obstacle to the commercialization of aqueous zinc ion batteries (AZIBs). Herein, we proposed LiF as a solid-electrolyte interphase for highly reversible Zn anode. Combining experimental analyses and theoretical simulation calculations, the electronegative fluorine atoms could provide uniform zincophilic nucleation sites to regulate Zn deposition behavior. Additionally, a ZnF2 layer with outstanding Zn2+ conductive can be formed insitu thus further shielding bulk water molecules and expediting the Zn2+ transfer kinetics. Therefore, the LiF@Zn symmetric cells manifest long-cycling stability with 650 h at 1.0 mA/cm2 and 1.0 mAh/cm2 and 1000 h at 2.0 mA/cm2 and 1.0 mAh/cm2. Meanwhile, the rate performance of Zn//MnO2 and Zn//NH4V4O10 full cells are also enhanced by the LiF coating. This work provides a horizon for the design of artificial protective layer and promotes the large-scale practical development of AZIBs.

Analysis of the Effect of Tilted Corner Cube Reflector Arrays on Lunar Laser Ranging

This paper primarily investigates the effect of the tilt of corner cube reflector (CCR) arrays on lunar laser ranging (LLR). A mathematical model was established to study the random errors caused by the tilt of the CCR arrays. The study found that, ideally, when the laser ranging pulse width is 10 picoseconds or less, it is possible to distinguish from which specific corner cubes within the CCR array each peak in the echo signal originates. Consequently, partial data from the echo can be extracted for signal processing, significantly reducing random errors and improving the single-shot precision of LLR. The distance obtained by extracting part of the echo can be reduced to the center position of the array, thereby providing multiple higher-precision ranging results from each measurement. This not only improves the precision of LLR but also increases the data volume. A simulation experiment based on the 1.2 m laser ranging system at Yunnan Observatories was conducted. By extracting one peak for signal processing, the single-shot precision improved from 32.24 mm to 2.52 mm, validating the theoretical analysis results. Finally, an experimental laser ranging system based on a 53 cm binocular telescope system was established for ground experiments. The experimental results indicated that the echo signal could identify the tilt state of the CCR array. By extracting the peak returned by the central CCR for signal processing, the ranging precision was greatly improved. Through theoretical analyses, simulation experiments, and ground experiments, a solution to reduce the random errors caused by the tilt of the CCR array was provided. This offers an approach to enhance the single-shot precision of future LLR and provides a reference for upgrading ground-based equipment at future laser ranging stations.

Second-sphere interactions promote antenna effects for selective sensing of DPA in TbIII-based organic frameworks

Investigating the emission patterns of Ln-metal-organic frameworks (MOFs) is crucial but challenging for rational design and selecting suitable MOFs. Firstly, theoretical calculation was used to predict the energy transfer efficiencies between the central ions (Eu3+/Tb3+) and the ligand (H3BTTC). The result indicates that Eu3+ can be completely sensitized and therefore Eu-BTTC with high energy transfer efficiency shows single-emission, whereas Tb3+ can only be partially sensitized and Tb-BTTC shows dual-emission due to reverse energy transfer. Subsequently, Eu-BTTC and Tb-BTTC with heterogeneous emission properties were successfully constructed. In order to investigate the emission modes of the two LnMOFs, 2,6-dipyridyl acid (DPA) was chosen as the second sphere and triggered the interaction between DPA and MOFs. In Eu-BTTC, the fluorescence remained constant before and after the addition of DPA due to the Eu3+ sensitized completely. In Tb-BTTC, the interaction between MOF and DPA improves the energy transfer efficiency from BTTC to Tb3+, resulting in the fully sensitization of Tb3+ and a significant enhancement of the fluorescence of Tb3+. In response to these results, a series of experiments as well as theoretical simulations were conducted to reveal the mechanism. A rational design mode and a novel sensing mechanism for the sensing platform of Ln-MOFs was provided by this study.

Preparation of tungsten-doped Ti-based lithium ion sieves with excellent adsorption performance by hydrothermal method

Ti-based Li-ion sieve (H2TiO3, HTO), is attractive for adsorbing lithium from salt lakes. Nevertheless, the titanium dissolution and limited adsorption capacity affect the cycling stability and adsorption performance. In this work, an atom engineering technique was employed by doping tungsten (W) into layered HTO via a hydrothermal method. Through experiments and theoretical simulation, it was demonstrated that the doped W in HTO results in expanded interplanar spacing, increased surface adsorption energy, and excellent adsorption performance. The optimized HTO-W exhibits an Ti dissolution rate of 0.73 % (in 2 mol L−1 HCl for 12 h, 5.6 % that of pristine HTO) and adsorption capacity of 43.01 mg g−1 (in 425 mg L−1 LiCl solution at 30 °C, 1.4 times that of undoped HTO). Furthermore, the HTO-W reaches adsorption equilibrium in about 3 h with exceptional selectivity and stability. This work demonstrates an effective enhancement of lithium adsorption by W doping, providing new avenues for developing lithium adsorbents with high performance.

Percolation Transitions in Edge-Coupled Interdependent Networks with Reinforced Inter-Layer Links.

Prior research on cascading failures within interdependent networks has predominantly emphasized the coupling of nodes. Nevertheless, in practical networks, interactions often exist not just through the nodes themselves but also via the connections (edges) linking them, a configuration referred to as edge-coupled interdependent networks. Past research has shown that introducing a certain percentage of reinforced nodes or connecting edges can prevent catastrophic network collapses. However, the effect of reinforced inter-layer links in edge-coupled interdependent networks has yet to be addressed. Here, we develop a theoretical framework for studying percolation models in edge-coupled interdependent networks by introducing a proportion of reinforced inter-layer links and deriving detailed expressions for the giant and finite components and the percolation phase transition threshold. We find that there exists a required minimum proportion of the reinforced inter-layer links to prevent abrupt network collapse, which serves as a boundary to distinguish different phase transition types of a network. We provide both analytical and numerical solutions for random and scale-free networks, demonstrating that the proposed method exhibits superior reinforcement efficiency compared to intra-layer link reinforcement strategies. Theoretical analysis, simulation results, and real network systems validate our model and indicate that introducing a specific proportion of reinforced inter-layer links can prevent abrupt system failure and enhance network robustness in edge-coupled interdependent networks.

The collective transportation of many self-propelled liquid metal droplets in Tesla valve

Gallium-based liquid metal droplet is active particle that maintains a liquid phase at room temperature and perform Self-propelled motion in electrolyte solutions. Unlike passive rigid particles, the collective transportation of swarming liquid metal droplets is strongly influenced by the surface tension, the shape deformation, the collision dynamics and the coalescence process of liquid metal droplets. We drive the swarming micron-sized Galinstan droplets to pass a Tesla microfluidic valve by applying external electric field, the diodicity of liquid metal droplet flow in Tesla valve is verified experimentally, which increases with respect to an increasing voltage. Theoretical simulations of flow field within the Tesla microfluidic valve suggested different turbulent flow field with opposite input flows. The coalescence of liquid metal droplets was enhanced when the Tesla valve blocks the flow. The collective transportation of swarming self-propelled liquid metal droplets has promising applications in biomedics, flexible electronics and swarm microrobotic technology.

Synergistic adsorption and UV degradation of perfluorooctanoic acid by amine-functionalized A-center sphalerite

Perfluorinated alkylated substances (PFAS), as a category of persistent organic pollutants, have garnered extensive concern due to their resilience against environmental degradation. Herein, we developed an amine-functionalized sphalerite (ZnS) with adjustable surface amine functional groups and Zn defects (ZnS-X%[N]) by in situ coprecipitation and simple hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). This material demonstrated efficient PFAS adsorption and subsequent photo-induced degradation under UV irradiation. The characterization results by TEM, BET, FTIR, XPS and EPR revealed that CTAB primarily influences ZnS by modulating surface amine functionalities, zinc defect density, and enhancing its photoreductive capacity. Adsorption and kinetic degradation experiments further showed that a medium CTAB concentration in ZnS-40%[N] achieves highest PFAS adsorption capacity (Cmax: 0.201 mol kg-1), and the corresponding decomposition rate was the fastest (kde: 1.53; kdf: 1.19). This efficacy is attributed to the ZnS-40%[N]'s ideal adsorptive sites and surface shallow defects. Moreover, theoretical simulation also supports the above experimental inference. Overall, ZnS-X%[N] exhibits a synergistic effect on PFAS adsorption and degradation, showcasing its potential for environmental adaptability and practical application.

A Host-Guest Approach to Engineering Oxidase-Mimetic Assembly with Substrate Selectivity and Dynamic Catalysis.

The creation of synthetic materials that emulate the complexity of natural systems, such as enzymes, remains a challenge in biomimicry. Here, we present a simple yet effective strategy to introduce substrate selectivity and dynamic responsiveness into an enzyme-mimetic supramolecular material. We achieved this by anchoring γ-cyclodextrin to a fluorene-modified Lys/Cu2+ assembly, which mimics copper-dependent oxidase. The binding affinity among the components was examined using 1H NMR, isothermal titration calorimetry (ITC), and theoretical simulation. The γ-cyclodextrin acts as a host, forming a complex with the fluorenyl moiety and aromatic substrates of specific sizes. This ensures the proximity of the substrate reactive groups to the copper center, leading to size-selective enhancement of aromatic substrate oxidation, particularly favoring biphenyl substrates. Notably, α- and β-cyclodextrins do not exhibit this effect, and the native oxidase lacks this selectivity. Additionally, the binding affinity of the aromatic substrate to the catalyst can be dynamically tuned by adding α-cyclodextrin or by irradiating with different wavelengths in the presence of competitive azo-guests, resulting in switched oxidative activities. This approach offers a new avenue for designing biomimetic materials with tailorable active site structures and catalytic properties.

Gel beads prepared by polyvinyl alcohol cross-linking with phytic acid and Fe as novel microbial carriers for simultaneous partial nitrification, anammox and denitrification

Enhancing the stability of biomass and ensuring a stable activity of anaerobic ammonia oxidizing bacteria are crucial for successful operation of the simultaneous partial nitrification, Anammox, and denitrification (SNAD) process. In this study, gel beads of polyvinyl alcohol/phytic acid (PVA/PA) and polyvinyl alcohol/phytic acid/Fe (PVA/PA/Fe) were prepared as innovative bio-carriers. Theoretical simulations and analyses revealed that these carriers are predominantly connected via hydrogen and borate bonds, with PVA/PA/Fe also featuring metal coordination bonds. The total nitrogen removal efficiency of reactors with PVA/PA/Fe and PVA/PA increased by 13.5 % and 9.0 %, respectively, compared to reactor without carriers. The iron-enriched PVA/PA/Fe carriers significantly improve SNAD by promoting Anammox, Feammox, and nitrate-dependent Fe2+ oxidation reactions, leading to faster nitrogen conversion and higher nitrogen removal rate than reactor without carriers and with PVA/PA. Using of PVA/PA and PVA/PA/Fe gel beads as bio-carriers offers benefits to the SNAD process, including cost-effective and low carbon requirement.

Research on Diffraction Patterns of Smartphone Screens

Smartphone screen is composed of pixels which are not of uniform size and arranged evenly. When illuminated by a laser, the reflected beam diffracts, producing a diffraction pattern with structure of mesh shape that exhibits characteristics similar to a two-dimensional reflection grating.In this paper, the general diffraction formula of a two-dimensional non-uniform grating is derived, while a simplified form in a special case is explored. The influence of laser incidence angle on the diffraction pattern is analyzed. The diffraction patterns by formula calculation and Fourier transform are obtained using MATLAB simulation. The rationality of the derived formula is verified through simulation and experiments. Also, the pixel density of the smartphone screen is calculated based on the diffraction pattern obtained from the experiment. The application scenarios of the research results are proposed.Comparing the discrepancy in diffraction patterns of different types of screens whose arrangements of sub pixels in smartphones are also different, the mechanism of grating diffraction is displayed directly. Theoretical calculations, simulations and experiments are applied for comparing and confirming each other.

Comparative review and novel design possibilities on solar-driven absorption LiBr-H2O refrigeration system

Solar energy is a promising source of energy because of its potential due to the reduction usage of non-renewable energy. As the demand for cooling increases, solar-powered cooling technologies are becoming increasingly promising. Among the different solar cooling systems, LiBr-H2O absorption chillers are commonly used due to their advantages over NH3-H2O systems. Multiple cycle LiBr-H2O chillers can be powered by easily available flat-plate, evacuated tubular or parabolic solar collectors. This paper reviews Theoretical Principles-Based Analysis and Simulations of solar LiBr-H2O absorption cooling systems, performance comparison of each types and introduces new design options related to auxiliary energy systems and cooling mode cycle. The paper also summarizes other main types of solar absorption cooling systems, including double-effect, half-effect, triple effect and give updates of new technology design of hybrid effect. The choice of water-cooled or air-cooled absorption refrigeration depends on the local climate and water availability. Recent advances have made air-cooled absorption refrigeration a viable option, with comparable COP to water-cooled systems and lower maintenance requirements. Additionally, geothermal heat rejection with low pressure drops can further reduce energy consumption. Solar-powered double-effect absorption cooling systems are recommended for buildings with high cooling loads, while half-effect are suitable for air-cooled solar absorption cooling systems in hot and dry regions with limited water. This paper is specifically intended for those interested in developing solar-driven LiBr-H2O absorption chillers, emphasizing the importance of establishing standardized design guidelines to specific regions and climates in order to promote and expand the usage of solar cooling systems.