Channel Blockage Research Articles

Hardware Realization of Long Range (LoRa) Based Telemetry System for Aquaculture Monitoring

Freshwater fish farming must pay attention to the condition of the water content in the pond and the water quality in the pond. Fish will feel comfortable if the efficiency of oxygen levels and pond water content is maintained. Freshwater fish farming needs to optimize crop yields so as not to get losses. The problem that is often encountered is that many fish die in the pond due to lack of water. Irrigation channels leading to fishponds experience blockages. The smoothness of the irrigation channel affects the volume of water in the pond. Blockage of irrigation channels is usually due to garbage trapped in irrigation, causing dirty water to settle and water sequestration to occur in the pond. This tool system aims to improve water quality and increase the efficiency of oxygen levels by using TDS and ultrasonic sensors. The parameter value on the sensor affects the work of the tool actuator. The tool actuator is a water pump that is used as a substitute for irrigation channels and an aerator motor to increase dissolved oxygen in water by moving the propeller on the surface of the pond water. Wireless technology is used for data communication. Because the land of freshwater fish farming ponds is a large area and is far from settlements, wireless communication is suitable for enabling easy and fast access to information and services. In this research, the testing methods used are functional testing and system performance testing. Functional testing is used to prove whether the system that has been implemented can meet the requirements of operational functions as planned. System performance testing is intended to monitor several parameters that can show the ability and reliability of the system in carrying out its operational functions. The result of the overall test is the LoRa communication distance that can communicate up to about 1000 meters, proving that LoRa technology has a strong enough ability in terms of range wireless communication. The PLE (Path Loss Exponent) of the LoRa module with 100 meters in LoS (indoor) conditions is 7.77, while in nLoS conditions in obstructed in-building, it is 10.13. The average error of the ultrasonic sensor type JSN SR-04T is 0.16% and has a difference of ± 1 cm. The TDS sensor with dissolved pool water content has an average value of 142.6 ppm with an error value of 1.05%. The PDAM water content has an average value of 112.1 ppm with a sensor value of 1.38%. The water content of the lime and detergent mixture has the highest observed ppm value, which is an average of 737.33 ppm, with a sensor error of 0.14%. The water pump activates when the pool water is low (when the ultrasonic distance reaches 60 cm), and the aerator activates when the water content is contaminated (when the TDS sensor value exceeds 500 ppm).

Intrinsic mechanism of influence of channel blocking and noise on response state of multicompartmental neurons

The fine structure of multi-compartment neurons can simultaneously capture both temporal and spatial characteristics, offering rich responses and intrinsic mechanisms. However, current studies of the effects of channel blockage and noise on neuronal response states are mainly limited to single-compartment neurons. This study introduces an analytical method to explore theintrinsic mechanism of channel blockage and noise effects on the response states of multi-compartment neurons, by using the smooth Pinsky-Rinzel two-compartment neuron model as a case study. Potassium, sodium, and calcium ion channel blockage coefficient are separately introduced to develop a smooth Pinsky-Rinzel neuron model with ion channel blockage. Methods such as single-parameter bifurcation analysis, double-parameter bifurcation analysis, coefficient of variation, and frequency characteristics analysis are utilized to examine the effects of various ion channel blockages on neuronal response states. Additionally, smooth Pinsky-Rinzel neuron Subunit noise model and conductance noise model are constructed to investigate their response characteristics by using interspike interval analysis and coefficient of variation indicators. Subthreshold stimulation is used to explore the presence of stochastic resonance phenomena. Single-parameter bifurcation analysis of the ion channel blockage model elucidates the dynamic processes of two torus bifurcations and limit point bifurcations in Pinsky-Rinzel neuron firing under potassium ion blocking. Double-parameter bifurcation analysis reveals a nearly linear increase in the Hopf bifurcation node of potassium ions with input current, whereas sodium ions exhibit a two-stage pattern of linear decline followed by exponential rise. The analysis of average firing frequency and coefficient of variation indicates that the moderate potassium channel blockage promotes firing, sodium channel blockage inhibits firing, and calcium channel blockage shows the complex characteristics but mainly promotes firing. Subthreshold stimulation of the channel noise model demonstrates the stochastic resonance phenomena in both models, accompanied by more intense chaotic firing, highlighting the positive role of noise in neural signal transmission. The interspike interval and coefficient of variation indicators show consistent variation levels for both noise models, with the conductance model displaying greater sensitivity to membrane area and stronger encoding capabilities. This study analyzes the general frequency characteristics of potassium and sodium ions in a multi-compartment neuron model through ion channel blocking model, providing special insights into the unique role of calcium ions. Further, the study explores stochastic resonance by using ion channel noise model, supporting the theory of noise-enhanced signal processing and offering new perspectives and tools for future studying complex information encoding in neural systems. By constructing an ion channel blockage model, the effects of potassium and sodium ions on the frequency characteristics of multi-compartment neurons are analyzed and the special influences of calcium ions are revealed. Using the ion channel noise model, the stochastic resonance is investigated, supporting the theory that the noise enhances signal processing. This research offers a new perspective and tool for studying the complex information encoding in neural systems.

Amide naphthotube as a novel supramolecular sequestration agent for tetracaine and decamethonium.

Anesthetics are widely used for optimizing surgical conditions, postoperative pain management, and treating various chronic pain conditions. Tetracaine and decamethonium are representative drugs of local anesthetics and neuromuscular blocking agents, respectively. However, overdose and toxicity of the drugs always lead to serious adverse events. Thus, there is a strong demand for effective antidotes. The binding interactions of amide naphthotubes with tetracaine and decamethonium were systematically studied using 1H NMR, ITC, and DFT calculations. The antidotal effects of amide naphthotube to tetracaine toxicity were assessed in vitro and in vivo, and the mechanism of detoxification was explored at a cellular level. Additionally, mouse models were established to evaluate the reversal activities of amide naphthotube on decamethonium-induced mortality and muscle relaxation, and the reversal mechanism was investigated through pharmacokinetic experiments. We have demonstrated that the anti-isomer of amide naphthotube exhibits significant binding affinities towards tetracaine (K a = 1.89×107 M-1) and decamethonium (K a = 1.01×107 M-1) in water. The host displayed good biocompatibility both in vitro and in vivo. The administration of amide naphthotube following tetracaine overdose in mouse models notably increased the overall survival rate, indicating its effective antidotal properties. The host could reverse the tetracaine-induced Na+ channels blockage at the cellular level. Moreover, the injection of amide naphthotube also reversed the mortality and paralysis induced by decamethonium in mouse models following a pharmacokinetic mechanism. An emerging artificial receptor, amide naphthotube, has strong binding affinities towards tetracaine and decamethonium. It functions as a supramolecular antidote for tetracaine poisoning and a reversal agent for decamethonium by selectively sequestering these compounds in vivo.

Role of Ayurveda in the Management of Becker Muscular Dystrophy: A Case Study

Abstract Muscular dystrophies are a group of genetic disorders that lead to a gradual weakening of muscles, resulting in increased disability over time. Becker muscular dystrophy (BMD) is one such condition and is inherited through an X-linked recessive pattern, primarily affecting males. Symptoms of BMD typically begin in the teenage years or late twenties. Initial signs may include muscle cramps during exercise and reduced stamina. Over time, there is a gradual loss of muscle bulk in the hips, pelvis, thighs, and shoulders, often leading to a tendency to walk on toes. In Ayurveda, the factors contributing to this disease are believed to be an aggravation of Vata (one of the three doshas), depletion of Mamsa (muscle tissue), and Meda (fat tissue), impaired digestive fire, and blockage of functional channels (Srotorodha). The present case involved a 15-year-old male with weakness in both lower limbs for 4 years, a decrease in muscle mass around the pelvic and thigh area for 3 years, and an increase in calf muscle size for 3 years. The patient exhibited pseudohypertrophy in both calf muscles and positive Gower’s sign, along with a positive family history and elevated creatine phosphokinase levels, leading to a diagnosis of BMD. The treatment approach incorporated Panchakarma therapies and internal Ayurvedic formulations in line with the management of Sarvang Vata disorder. The treatment was administered in four sessions, with a 3-month gap between each therapy session. After a year of treatment, there was not only a halt in the progression of the disease but also a notable improvement in lower limb strength, which increased from 4 to 4+. In addition, there was an increase in proximal muscle mass, from 12.5 inches to 13 inches, and a reduction in calf muscle size and tightness. This promising outcome suggests the potential for managing the disease using Ayurvedic principles and therapies.

Energy dissipation mechanism of tip-leakage cavitation in mixed-flow pump blades

Tip leakage flow is one of the significant factors influencing the internal flow stability of mixed-flow pumps, and in severe cases, it can lead to channel blockage and energy loss. In order to gain a deeper understanding of the energy dissipation mechanism induced by tip leakage vortex cavitation, this study is based on the Wray–Agarwal (WA) turbulence model and the homogeneous flow model, investigating the cavitation flow characteristics of mixed-flow pumps. Additionally, the entropy production theory is employed to evaluate the energy losses within the mixed-flow pump and analyze the components of energy loss in the impeller and guide vanes. The research results reveal that with increasing cavitation intensity, the low-pressure region at the leading edge of the blade extends toward the trailing edge, influencing the static pressure distribution on the blade's pressure side. Leakage flow and the spatial distribution of leakage vortices move closer to the suction side of the blade with increasing cavitation intensity. Cavitation primarily affects the energy losses in the impeller region, with turbulent dissipation being the main source of energy loss. High turbulent dissipation zones are concentrated at the trailing edge of the blade, correlating with recirculation vortices and trailing-edge vortices. This study provides theoretical insights with practical implications for enhancing the cavitation performance of mixed-flow pumps, offering valuable guidance for design and operation.

Effects of small marine energy deployments on oceanographic systems

The placement and operation of marine energy deployments in the ocean have the potential to change flow patterns, decrease wave heights, and/or remove energy from the oceanographic system. Changes in oceanographic systems resulting from harvesting marine energy, particularly tidal and wave energy, may be of concern. These changes include alterations in nearfield and farfield physical processes, as well as potential secondary environmental effects such as changes in sediment transport patterns, biological processes, or coastal erosion. Knowledge of changes in oceanographic systems associated with marine energy is primarily available from numerical modeling studies, informed by some laboratory tests and very few field measurements. A literature review was conducted using the Tethys knowledge base and other online sources, building on conclusions from the Ocean Energy Systems-Environmental State of the Science report. Potential changes in oceanographic systems that may be caused by marine energy differ between tidal and wave devices because of different extraction mechanisms and siting locations. Numerical models show that tidal extraction on the order of hundreds of megawatts or with significant channel blockage is required to create changes in oceanographic processes that exceed natural variability. Effects from wave energy extraction in arrays are localized and dependent on array spacing and proximity to the shore. Available evidence supports the conclusion that the risk of significant environmental effects from such changes could be retired (i.e., less investigation required for every project) for small deployments—those representative of the state of the industry in 2021. Determining changes in oceanographic systems to be low risk for small deployments can thereby streamline environmental consenting by reducing monitoring needs at this early stage in the industry.

Development of maldistribution of humid nitrogen condensing flow and the blockage in parallel channels

Maldistribution in parallel flow fields reduces the performance of proton exchange membrane fuel cells (PEMFCs) and heat exchangers. In this study, a condensing flow experiment was conducted in which water vapor condensed while humid nitrogen flowed through a parallel flow field with eight channels. The flow maldistribution across channels and blockage in channels induced by condensed water were investigated by measuring the flow rates in the channels and the pressure drop across the flow field. The results show that the development of the condensing flow can be divided into developing and quasi-steady stages according to the evolution of the flow rate and pressure drop. At a high nitrogen flow rate, the maldistribution was more severe during the developing stage than during the quasi-steady stage. In contrast, at a low nitrogen flow rate, the maldistribution was more severe in the quasi-steady stage, which can be attributed to the complete blockage induced by liquid water in the channels in this stage. Finally, at low nitrogen flow rates, the extent of maldistribution and duration of complete blockage decreased remarkably with an increase in the water molar fraction.

Identification Method of River Blocking by Debris Flow in the Middle Reaches of the Dadu River, Southwest of China

Debris flow is a typical natural disaster in the middle reaches of the Dadu River, which seriously threatens the safety of life and property of local residents. However, there is currently a lack of a comprehensive analysis methods applicable to the blockage of river channels by debris flow in the Dadu River basin, limiting disaster prevention and mitigation in this area. Based on previous large-scale model tests carried out in the middle reaches of the Dadu River, the debris flows are divided into dam-type debris flows and submerged debris flows. The calculation formulas for the maximum travel distance of the two kinds of debris flows entering the river are obtained via theoretical derivation. The formulas for calculating the length and volume of debris flow accumulation are derived, and the relationship between the debris flow loss coefficient and river blocking degree in the middle part of the Dadu River is analyzed. An identification method of river blocking by debris flow is put forward in this study. By calculating the maximum blocking degree, S (the ratio of the maximum driving distance of the debris flow to the width of the river), and the volume of the source materials needed to form a debris flow dam under the conditions that the debris flow does not reach the opposite bank (V1), reaches the opposite bank but does not block the river (V2), and reaches the opposite bank (V3), the form of debris flow blocking the river is distinguished. When S = 1, V > V3, complete blockage occurs; when S = 1, V > V2, the river is mostly blocked; when S < 1, V > V1, the river is half-blocked. This study established an identification method of river blocking by debris flow, providing a basis for early warning for river blocking and disaster prevention in the middle reaches of the Dadu River.

Safety analysis of pressurized water reactors with annular fuel during different transients

The dual-cooled annular fuel has two channels, with a shorter heat transfer path and a larger heat transfer area than solid fuel, which can effectively improve the safety of the reactor. It has excellent potential to improve the economy of the pressurized water reactor (PWR) and is considered to have a good development prospect. In this paper, the safety of the reactor with annular fuel assemblies under different transient conditions is analyzed using the system code NUSOL-SYS and the subchannel code NACAF, with the CPR1000 as the reference power plant. The analysis mainly includes the large break loss of coolant accident (LBLOCA), main steam line break accident (MSLB), loss of flow accident (LOFA), and rod ejection accident (REA) under nominal power and higher power density. The flow blockage accident and the combined accidents of LBLOCA and the flow blockage accident are also evaluated. The results show that during LBLOCA, the peak cladding temperature (PCT) of the core is only 833 K, much lower than that of the solid fuel. In addition, the departure from nucleate boiling ratio (DNBR) of annular fuel is larger during MSLB and LOFA, which means a more negligible risk of fuel damage. In REA, the average temperature of annular fuel is below 900 K, and the average enthalpy is below 200 kJ/kg, which is much lower than that of solid fuel. The results at 150 % power show that the performance of the core with annular fuel is still better than that of solid fuel at nominal power, except that the PCT during LBLOCA is slightly higher than solid fuel at nominal power. During the flow blockage accident, the results with different blockage areas show that a small proportion of blockage of the inner channel does not have a significant effect on the cladding temperature and that there is a risk of rupture when the inner channel is completely blocked. Finally, the results of the assumed combined accident show that the blockage of the inner channel before scram will significantly increase the PCT of the core and the time to complete the reflood during LBLOCA.

Iron diselenide/carbon black loaded mushroom-shaped evaporator for efficiently continuous solar-driven desalination

Solar-driven desalination is an environmentally sustainable method to alleviate the problems of freshwater scarcity and the energy crisis. However, how to improve the synergy between the photothermal material and the evaporator to achieve high photothermal conversion efficiency simultaneously, excellent thermal management system and good salt resistance remains a challenge. Here, a mushroom-shaped solar evaporation device is designed and fabricated with iron diselenide/carbon black (FeSe2/CB) coated cellulose acetate (CA) film as mushroom surface and cotton swab as mushroom handle, which presented high solar-driven evaporation and excellent salt resistance. Thanks to the unique photothermal effect and the synergistic effect, the FeSe2/CB composites enabled a promising photothermal conversion efficiency of up to 65.8 °C after 180 s. The mushroom-shaped evaporation device effectively overcomes water transport and steam spillage channel blockage caused by salt crystallization through its unique vertical transport water channels and conical air–water interface. When exposed to real sunlight, the solar evaporation rate of the steam generation structure reached as high as 2.03 kg m−2 h−1, which is more than 13 times higher than natural evaporation. This study offered new insights into the higher solar-driven evaporation rate and salt-blocking resistance of the FeSe2/CB mushroom-shaped solar evaporation device for solar-powered water production.

The Effect of Obstacle Number, Shape and Blockage Degree in Flow Field of PEMFC on its Performance

<p>Proton exchange membrane fuel cell (PEMFC) has received extensive attention as it is the most common hydrogen energy utilization device. This research not only investigated the effect of obstacle number and shape on PEMFC performance, but also studied the effect of the blockage degree in the channel of PEMFC on its performance. It was found that compared with traditional scheme, longitudinally distributed obstacles scheme can significantly promote reactants transfer to catalyst layer, and the blockage degree in the channel effect PEMFC performance most. The scheme with 10 rectangular obstacles in single channel and 60% channel blockage had the best output performance and the most uniform distribution of reactants and products. Obstacle height distribution can significantly affect PEMFC performance, the blockage degree in the whole basin was large, particularly as the channel was blocked to higher degree in region 2 and region 3, higher net power density and better mass transfer effect can be obtained. Among them, the fuel cell with the blockage degree of 40%, 60% and 60% in region 1, region 2 and region 3 have the best PEMFC output performance and mass transfer, the net power density was 29.8% higher than that of traditional scheme.</p>

Adaptive Gating Enhances Intelligent Membranes for Cellular Functions and Precise Separations

AbstractIntelligent membranes with adaptive gating channels play a crucial role in cellular functions and separation processes. This study introduces a novel approach to controlling channel expansion using biomimetic adaptive aggregates, fundamentally overcoming the drawbacks of existing methods relying on intertwined polyelectrolyte chains for channel blockage. Specifically, a pH‐responsive 2D material membrane is constructed through the self‐assembling of protein‐mimetic zwitterionic polydopamine (ZPDA) soft molecular aggregates within graphene oxide (GO) interlayers. Similar to the conformational switch of inserted proteins in cellular membranes, the embedded ZPDA in GO nanofluidic channels undergoes an adaptive conformational transformation in response to pH changes. This dynamic adjustment of ZPDA physicochemical properties allows for reversible regulation of GO nanofluidic channel size and charge by external pH modulation. The resulting GO/ZPDA membrane exhibits programmable separation performance for dye molecules (i.e., water permeance of 18.8–35.4 L m−2 h−1 bar−1 and molecular selectivity of 73.7–32.9) and salt ions (i.e., ionic permeance of 0.69–1.25 mol m−2 h−1 and ionic selectivity of 20.8–21.9). This work sheds new light on the engineering of intelligent stimuli‐responsive 2D nanofluidic channels with adaptive gating properties, holding promise across a wide range of applications including separation, drug delivery, sensing, and catalysis.

Weak Signal Detection in the Hodgkin–Huxley Neural Network with Channel Blocks under Electromagnetic Stimulus

Neurons can detect weak signals in noisy cellular environments and complex backgrounds. Channel blocks have a great impact on the initiation and propagation of action potentials for neurons. The effects of channel blocks and electromagnetic stimulus on weak signal detection are studied in Hodgkin–Huxley neuronal network. The results suggest that the weak signal detection and the neural discharge behaviors of the neural network can be suppressed by the sodium channel blockage, whereas the block of potassium channels will have a positive impact on the signal detection and neuronal firing. For moderate membrane patch size, there is an optimal ratio of non-blocked potassium channels that maximize improvement in the detection of weak signals and the regularity of the neuronal activities. The combined influence of the two channel blocks on weak signal detection can be modulated by the ratio between the number of the sodium channels and potassium channels that function properly. The electromagnetic stimulus can significantly ameliorate the damage caused by the poisoning of sodium ion channels. In addition, synchronization of the neural network can promote weak signal detection.

Enhancement of two-phase flow and mass transport by a two-dimensional flow channel with variable cross-sections in proton exchange membrane fuel cells

A novel two-dimensional flow channel (TDFCH) with variable cross-sections geometrically controlled by sinusoidal function is proposed for proton exchange membrane fuel cells (PEMFCs). Two-phase flow simulations and visualisation experiments are combined to reveal the mechanisms for improved water management and enhanced reactant transport. Results show that the centrifugal force generated by the vortex pushes the liquid water away from the central region of the flow channel, forming droplet and film flows to avoid blockage of the flow channel. The reactant gases accumulate on the windward side of the variable-diameter structures, leading to an increase of the local pressure and facilitating fuel diffusion into the porous electrode. The fluid inertia enhances mass transfer of reactants and removal of liquid water inside the porous electrode. The amplitude A of the flow channel based on sinusoidal curve plays a dominant role in improving the performance of the TDFCH. Under the same testing conditions, when amplitude A = 0.2 and period T = 2, the peak power density of the TDFCH-based cell reaches 517.9 mW cm−2, which is 26 % higher than the conventional straight flow channel. The newly designed TDFCH provides an efficient solution to realize performance improvement and long-term stable operation of PEMFCs.

Accident tolerant fuels behavior analysis for Pressurized Water reactor in steady state and transient conditions

Nuclear Fission Technology (NFT) is constantly developing to seek an increasingly safer operation and, consequently, increase the public acceptance of nuclear energy generation. Therefore, the development of new types of nuclear fuels and the search for different materials for cladding fuel rods has been the subject of research mainly to provide better efficiency in to carry energy in nuclear reactors and also to reduce possible damages in accident situations. In this way, this work aimed to compare the thermal response and behavior of Zircaloy 4, SiC reinforced with Hi-Nicalon type S (HNS) and FeCrAl alloy when they were considered as fuel cladding at steady state and transient conditions during operation of a PWR (Pressurized Water Reactor). Two thermal hydraulic models using the RELAP5 MOD3.3 and RELAP5-3D v. 4.3.4 codes and the reference data from the document Final Safety Analysis Report of Angra 2 PWR were used to perform the investigations. The work was developed in two steps. In the first one, the results of the Angra 2 nodalization in steady state conditions were compared with the Angra 2 reference data, obtaining good agreement. In the second step, the thermal response, when the cladding materials were changed, was evaluated in steady state and transient situations. The transients LOFA (Loss of Flow Accident), LBLOCA (Large Break - Loss of Coolant Accident), and coolant channel blockage were simulated in extreme conditions. The results have shown that substituting Zircalloy 4 alloy by FeCrAl or ceramic cladding SiC HNS presented a similar and better thermal response. Moreover, in another simulation, UO2 fuel has been replaced by U3Si2. The results showed lower temperatures at the fuel center in the rods with U3Si2 than those using UO2 as nuclear fuel, demonstrating the advantages of using U3Si2 fuel concerning the radial heat transfer in the rod.

Utilizing Heteroatom Types and Numbers from Extensive Ligand Libraries to Develop Novel hERG Blocker QSAR Models Using Machine Learning-Based Classifiers.

The human ether-à-go-go-related gene (hERG) channel plays a crucial role in membrane repolarization. Any disruptions in its function can lead to severe cardiovascular disorders such as long QT syndrome (LQTS), which increases the risk of serious cardiovascular problems such as tachyarrhythmia and sudden cardiac death. Drug-induced LQTS is a significant concern and has resulted in drug withdrawals from the market in the past. The main objective of this study is to pinpoint crucial heteroatoms present in ligands that initiate interactions leading to the effective blocking of the hERG channel. To achieve this aim, ligand-based quantitative structure-activity relationships (QSAR) models were constructed using extensive ligand libraries, considering the heteroatom types and numbers, and their associated hERG channel blockage pIC50 values. Machine learning-assisted QSAR models were developed to analyze the key structural components influencing compound activity. Among the various methods, the KPLS method proved to be the most efficient, allowing the construction of models based on eight distinct fingerprints. The study delved into investigating the influence of heteroatoms on the activity of hERG blockers, revealing their significant role. Furthermore, by quantifying the effect of heteroatom types and numbers on ligand activity at the hERG channel, six compound pairs were selected for molecular docking. Subsequent molecular dynamics simulations and per residue MM/GBSA calculations were performed to comprehensively analyze the interactions of the selected pair compounds.

Enhanced stability of Pt@S-1 with the aid of potassium ions for n-hexane and n-heptane aromatization

As a typical high-efficient alkane aromatization catalyst, Pt/KL is prone to deactivation due to the sintering growth of Pt on the outer surface of KL and the channel blockage caused by carbon deposition, which is further exacerbated by the one-dimensional channel structure of KL. Therefore, a series of encapsulated catalysts combining the three-dimensional channel structure advantages of S-1 with the role of potassium are prepared and evaluated. It is shown that the encapsulated catalyst KPt@S-1-02 modified by moderate potassium exhibits extremely superior stability and no significant deactivation is observable after n-heptane aromatization for 180 h under harsh conditions. On the one hand, encapsulation structure enables a strong anti-agglomeration ability of Pt and the topological structure of S-1 endows the encapsulation catalysts less susceptible to channel blockage, which has been demonstrated by HAADF-STEM and N2-adsorption. On the other hand, characterizations involving NH3-TPD, CO-DRIFT and HAADF-STEM verify that the modification by an appropriate amount of K can inhibit acid sites of catalysts and improve Pt dispersion and electron density, thus enhance the stability of catalysts. However, excessive K can serve as weak acid sites, poison of active sites and inhibitor of H2 adsorption on Pt surface, leading to deactivation of the catalyst.

Unveiling the Structural Characteristics of Intergrowth Zeolites Synthesized in the Presence of Isopropylimidazolium-Based Cations and Fluoride Anions.

Here, we present the synthesis of RTH/ITE and MEL/MFI intergrowth zeolites using 2-isopropylimidazolium-based cations as organic structure-directing agents (OSDAs) in concentrated fluoride media and their local structural properties. Phase selectivity in the synthesis of zeolite intergrowths was found to differ according to the concentration of OSDA cations and fluoride anions in the synthesis mixture as well as to the type of OSDA employed. Molecular modeling results suggest that the crystallization of intergrowth zeolites in fluoride media may be kinetically rather than thermodynamically controlled, as in ordered zeolites. Cs-corrected STEM analysis of MEL/MFI crystals synthesized at HF/OSDA = 2.0 in the presence of 2-isopropyl-1,3-dipropylimidazolium ions as an OSDA indicates the existence of previously unobserved MEL-MFI intergrowth along the [100] direction, leading to a partial blockage of MEL 10-ring channels.

Influence of the chordwise distribution of tip winglets on the stability of a high-load compressor stage

Compressor rotor blade tip winglet technology has been confirmed to be a passive flow control method that is effective in increasing the operating stability of compressors. As revealed by extensive research, the structural parameters of tip winglets are capable of affecting their stability expansion effect, whereas their mechanism and influence law of the compressor stage remains unclear. In this study, the effect exerted by the chordwise distribution of tip winglets on the stability of a high-load compressor stage was investigated. As indicated by the result of this study, the tip winglet exhibiting a proper widest position and an adequate chordwise length can effectively increase the stall margin. To be specific, the widest position was located at 25% chord, and the stall margin was increased by up to 25.39%. A winglet exhibiting a chordwise length of 50% achieved the stability expansion ability equivalent to winglet with a full chordwise length, which can be increased by 22.58%. The tip leakage flow turned out to be weakened as the axial momentum was increased, and the circumferential momentum of the flow that arose from the tip winglet was reduced. The result of this study also suggested that tip winglets can play a certain role in combing the inflow of the stator, such that the blockage of the stator channel can be reduced.

Atomistic insights into the effect of temperature on capillary transport of water molecules in epoxy-modified calcium silicate hydrate nanopore: diffusion, kinetics, and mechanism

The movement of water molecules at the atomic scale within the calcium silicate hydrate (C–S–H) gel pores serves a dual role: it creates an environment for harmful chemical reactions within the pores and functions as a carrier for the transport of detrimental ions, thereby affects the mechanical properties and durability of cementitious materials. However, direct experimental observation poses substantial challenges. This study offers new insights into how temperature (253 K, 273 K, 293 K, and 313 K) affects the capillary transport of water molecules in epoxy-modified C–S–H. The findings demonstrate that the pore size undergoes continuous changes during immersion due to epoxy clustering or detachment, resulting in three scenarios: narrowing of epoxy/C–S–H channels (253 K, 273 K), channel blockage (293 K), and complete detachment (313 K). Moreover, the interactions between water molecules and epoxy lead to epoxy detachment or cluster formation on the C–S–H surface. As the temperature increases, the interaction between C–S–H and cross-linked epoxy resin weakens. The coordination between C–S–H and epoxy resin decreases, while the coordination with water increases. This paper provides valuable insights into the transport behavior of liquids within the epoxy-modified C–S–H pores of cement-based materials. It contributes to a better understanding of how liquids move and interact within the modified pore structure, which is beneficial for enhancing the performance and properties of cement-based materials.