Artificial Channels Research Articles

Velocity field and turbulence structure of the meandering flow produced by alternating deflectors

Meandering flow can be formed during the advance of natural rivers by the scouring of river banks. However, this phenomenon is not common in artificial cement channels. This study used experimental scouring terrain data for a numerical simulation to study the meandering flow pattern formed between double alternating deflectors in a straight channel. The numerical results showed that the path of the accelerated flow generated by the upstream deflector was changed by installing a downstream deflector while the flow rate remained unchanged. Thus, a meandering flow formed, and a stable, narrow, high-speed zone formed in the downstream area. The accelerated flow between the two deflectors hit the channel bank soon after its direction changed. Then, a strong downward flow formed in this area, which may have produced an elliptical scour hole. A large-scale vortex structure was formed in the elliptical scour hole, which was influenced by the horseshoe vortex system before the downstream deflector.

Concentration-Driven Evolution of Adaptive Artificial Ion Channels or Nanopores with Specific Anticancer Activities.

In nature, ceramides are a class of sphingolipids possessing a unique ability to self-assemble into protein-permeable channels with intriguing concentration-dependent adaptive channel cavities. However, within the realm of artificial ion channels, this interesting phenomenon is scarcely represented. Herein, we report on a novel class of adaptive artificial channels, Pn-TPPs, based on PEGylated cholic acids bearing triphenylphosphonium (TPP) groups as anion binding motifs. Interestingly, the molecules self-assemble into chloride ion channels at low concentrations while transforming into small molecule-permeable nanopores at high concentrations. Moreover, the TPP groups endow the molecules with mitochondria-targeting properties, enabling them to selectively drill holes on the mitochondrial membrane of cancer cells and subsequently trigger the caspase 9 apoptotic pathway. The anticancer efficacies of Pn-TPPs correlate with their abilities to form nanopores. Significantly, the most active ensembles formed by P5-TPP exhibits impressive anticancer activity against human liver cancer cells, with an IC50 value of 3.8 μM. While demonstrating similar anticancer performance to doxorubicin, P5-TPP exhibits a selectivity index surpassing that of doxorubicin by a factor of 16.8.

Concentration‐Driven Evolution of Adaptive Artificial Ion Channels or Nanopores with Specific Anticancer Activities

AbstractIn nature, ceramides are a class of sphingolipids possessing a unique ability to self‐assemble into protein‐permeable channels with intriguing concentration‐dependent adaptive channel cavities. However, within the realm of artificial ion channels, this interesting phenomenon is scarcely represented. Herein, we report on a novel class of adaptive artificial channels, Pn‐TPPs, based on PEGylated cholic acids bearing triphenylphosphonium (TPP) groups as anion binding motifs. Interestingly, the molecules self‐assemble into chloride ion channels at low concentrations while transforming into small molecule‐permeable nanopores at high concentrations. Moreover, the TPP groups endow the molecules with mitochondria‐targeting properties, enabling them to selectively drill holes on the mitochondrial membrane of cancer cells and subsequently trigger the caspase 9 apoptotic pathway. The anticancer efficacies of Pn‐TPPs correlate with their abilities to form nanopores. Significantly, the most active ensembles formed by P5‐TPP exhibits impressive anticancer activity against human liver cancer cells, with an IC50 value of 3.8 μM. While demonstrating similar anticancer performance to doxorubicin, P5‐TPP exhibits a selectivity index surpassing that of doxorubicin by a factor of 16.8.

Redox-Regulated Synthetic Channels: Enabling Reversible Ion Transport by Modulating the Ion-Permeation Pathway.

Natural redox-regulated channel proteins often utilize disulfide bonds as redox sensors for adaptive regulation of channel conformations in response to diverse physiological environments. In this study, we developed novel synthetic ion channels capable of reversibly switching their ion-transport capabilities by incorporating multiple disulfide bonds into artificial systems. X-ray structural analysis and electrophysiological experiments demonstrated that these disulfide-bridged molecules possess well-defined tubular cavities and can be efficiently inserted into lipid bilayers to form artificial ion channels. More importantly, the disulfide bonds in these molecules serve as redox-tunable switches to regulate the formation and disruption of ion-permeation pathways, thereby achieving a transition in the transmembrane transport process between the ON and OFF states.

Redox‐Regulated Synthetic Channels: Enabling Reversible Ion Transport by Modulating the Ion‐Permeation Pathway

AbstractNatural redox‐regulated channel proteins often utilize disulfide bonds as redox sensors for adaptive regulation of channel conformations in response to diverse physiological environments. In this study, we developed novel synthetic ion channels capable of reversibly switching their ion‐transport capabilities by incorporating multiple disulfide bonds into artificial systems. X‐ray structural analysis and electrophysiological experiments demonstrated that these disulfide‐bridged molecules possess well‐defined tubular cavities and can be efficiently inserted into lipid bilayers to form artificial ion channels. More importantly, the disulfide bonds in these molecules serve as redox‐tunable switches to regulate the formation and disruption of ion‐permeation pathways, thereby achieving a transition in the transmembrane transport process between the ON and OFF states.

Naphthalene Diimide-Based Metallacage as an Artificial Ion Channel for Chloride Ion Transport.

Developing synthetic molecular devices for controlling ion transmembrane transport is a promising research field in supramolecular chemistry. These artificial ion channels provide models to study ion channel diseases and have huge potential for therapeutic applications. Compared with self-assembled ion channels constructed by intermolecular weak interactions between smaller molecules or cyclic compounds, metallacage-based ion channels have well-defined structures and can exist as single components in the phospholipid bilayer. A naphthalene diimide-based artificial chloride ion channel is constructed through efficient subcomponent self-assembly and its selective ion transport activity in large unilamellar vesicles and the planar lipid bilayer membrane by fluorescence and ion-current measurements is investigated. Molecular dynamics simulations and density functional theory calculations show that the metallacage spans the entire phospholipid bilayer as an unimolecular ion transport channel. This channel transports chloride ions across the cell membrane, which disturbs the ion balance of cancer cells and inhibits the growth of cancer cells at low concentrations.

Phenotype‐dependent downstream dispersal under ordinary flow conditions in juvenile white‐spotted char

AbstractAnimal dispersal is often phenotype‐dependent and can exert evolutionary pressures on populations in which it occurs. The evolutionary pressure arising from phenotype‐dependent dispersal is called spatial sorting. We examined the evolutionary pressure arising from spatial sorting (sorting pressure) caused by downstream dispersal in juvenile white‐spotted char Salvelinus leucomaenis under ordinary flow conditions. We conducted outdoor experiments using an artificial channel with 10 steps to investigate the relationship between phenotypic characteristics and the occurrence or distance of downstream dispersal during five daytime hours. Six experiments were conducted using young‐of‐the‐year juveniles collected early in the morning of each experimental day. We focused on two phenotypes, fork length (body size) and station‐holding (SH) behavior, where juveniles remain sedentary on the substrate. Juveniles were assigned to the “SH group” if they exhibited SH behavior for more than 10 s during a 540‐s observation period, and to the “swimming group” if they exhibited SH behavior for less than 10 s. Juveniles in the swimming group had a higher occurrence of downstream dispersal than in the SH group. In addition, large juveniles in the SH group and small juveniles in the swimming group tended to show long dispersal distances. These results suggest an effective sorting pressure against juveniles with active swimming behavior. This sorting pressure may accumulate in isolated char populations located above a tall migration barrier and contribute to the creation and maintenance of the reported interpopulation variation in SH behavior.

Effect of equilibrium and non-equilibrium sediment transport flows on the shear velocity in an open channel.

Equilibrium and non-equilibrium sediment transport flow in natural rivers and artificial channels can result in degradation or aggradation of the river bed, which will affect many hydraulic parameters, one of which is shear velocity. This study evaluates the influence of sediment transport on shear velocity in open channels. In this study, laboratory experiments were carried out using a sediment-recirculating flume, and measurements of the velocity and Reynolds shear stress distributions were measured using a Sontek-acoustic Doppler velocimeter (ADV). This experimental study measured 120 velocity distributions, and Reynolds stress profiles, consisting of 12 different sets of measurements involving flow with sediment transport and movable sand bed. The results showed an average shear velocity, u*, difference between sediment feeding and without sediment feeding by 9.41%. For the integration constant Br value, the average difference between sediment feeding and without sediment feeding was 5.58%.

Advanced flow simulations of estuarine water resources responding to changes in societal demands

Water resources of rivers and estuaries have traditionally been managed for local societal demands, including municipal, agricultural, and industrial usages, as well as for transportation as navigational channels. However, as societal demands have changed including urban expansion, economic growth, cultural transition, etc., the land uses also should be changed, and the civil necessities of water have been diversified, and this has raised concerns about the ecology, environment, and water quality issues. This study attempted to address three water resource management issues in South Korean rivers and estuaries, which occurred recently due to the changes in societal demands for water and explained how the most advanced scientific research techniques had been applied. The main issues were 1) agricultural water security and ecological environment restoration in Nakdong River Estuary, 2) water and soil quality degradation due to industrial effluents in Hyeongsan River Estuary, and 3) utilization of rivers as waterways and water quality and ecology issues in the ARA waterway. To find solutions to conflicts of water resources, the series of numerical simulations validated by the field observations allowed 1) assessments of the impact and extent of salt intrusion upon the opening of estuary dam gates, 2) estuarine physical processes to investigate the influence of industrial effluent, and 3) analysis water quality variations resulting from changes in the function of artificial channels. These analyses are expected to provide appropriate and science-based strategies of regional water management.

Ultrahigh Lithium Selective Transport in Two-Dimensional Confined Ice.

Inspired by selective ion transport in biological membrane proteins, researchers developed artificial ion channels that sieve monovalent cations, catering to the increasing lithium demand. In this work, we engineered an ion transport channel based on the confined ice within two-dimensional (2D) capillaries and found that the permselectivity of monovalent cations depends on the anisotropy of the confined ice. Particularly, the 2D confined ice showed an anomalous lithium selective transport along the (002) direction in the vermiculite capillary, with the Li+/Na+ and Li+/K+ permselectivity reaching up to 556 ± 86 and 901 ± 172, respectively, superior to most ion-selective channels. However, the 2D confined ice along the (100) direction showed less Li+ permselectivity. Additionally, the anisotropy of 2D confined ice can be tuned by adjusting the interlayer spacing. By providing insights into the ion transport in the 2D confined ice, our work may inspire more design of monovalent ion-selective channels for efficient lithium separation.

Artificial Water Channel Promoting Depolymerization of Actin Filaments to Trigger Cancer Cell Apoptosis

Comprehensive SummaryActin filaments play important physiological functions, which have become potential targets of antitumor drugs. Using chemicals to intervene their polymerization‐depolymerization dynamics would generate new strategies for designing antitumor drugs. In this report, an artificial water channel appending acetazolamide moiety, a ligand that can selectively bind to carbonic anhydrase IX, has been prepared. We demonstrated that this conjugate can target colorectal cancer cells overexpressing carbonic anhydrase IX and trigger the depolymerization of actin filaments of the cancer cells by selectively mediating water transmembrane transport. Moreover, the conjugate‐promoted actin depolymerization led to tumor cell apoptosis and its high antitumor activity in vitro and in vivo against colorectal cancer. The method described herein represents a new and general strategy for designing antitumor drugs by using artificial channel‐mediated selective water transport to promote actin depolymerization.

Artificial DNA Framework Channel Modulates Antiapoptotic Behavior in Ischemia-Stressed Cells via Destabilizing Promoter G-Quadruplex.

Regulating folding/unfolding of gene promoter G-quadruplexes (G4s) is important for understanding the topological changes in genomic DNAs and the biological effects of such changes on important cellular events. Although many G4-stabilizing ligands have been screened out, effective G4-destabilizing ligands are extremely rare, posing a great challenge for illustrating how G4 destabilization affects gene function in living cells under stress, a long-standing question in neuroscience. Herein, we report a distinct methodology able to destabilize gene promoter G4s in ischemia-stressed neural cells by mitigating the ischemia-induced accumulation of intracellular K+ with an artificial membrane-spanning DNA framework channel (DFC). We also show that ischemia-triggered K+ influx is positively correlated to anomalous stabilization of promoter G4s and downregulation of Bcl-2, an antiapoptotic gene with neuroprotective effects against ischemic injury. Intriguingly, the DFC enables rapid transmembrane transport of excessive K+ mediated by the internal G4 filter, leading to the destabilization of endogenous promoter G4 in Bcl-2 and subsequent turnover of gene expression at both transcription and translation levels under ischemia. Consequently, this work enriches our understanding of the biological roles of endogenous G4s and may offer important clues to study the cellular behaviors in response to stress.

The rainstorm waterlogging resistance of a novel fiber-reinforced self-compacting recycled pervious concrete after freeze-thaw cycles

The poor permeability of pervious concrete after freeze-thaw (F-T) cycles is a difficult issue in the face of frequent extreme rainstorms, causing urban rainstorm waterlogging problems (stagnant water depth exceeds 150 mm). A novel fiber-reinforced self-compacting recycled pervious concrete (NSPC) with low tortuosity artificial pore channel (APC) is a pervious material with high permeability and strength, and has potential application in pervious pavement at the coupling action of F-T cycles and rainstorm. In this study, the frost resistance, mechanical properties and permeability of C60 NSPC (pore diameter of 3 mm, porosity of 1.13%) with various steel fiber contents (0 vol%, 0.5 vol%, 1 vol%, 1.5 vol% and 2 vol%) were investigated, and then the rainstorm waterlogging resistance of NSPC after 300 F-T cycles was examined under 20-, 50- and 100-year rainstorm. Results showed that the macroscopic destruction of NSPC surface after F-T cycles always started near the APCs, and the existence of APCs aggravated the mass loss and the decrease of the relative dynamic modulus of elasticity. As the increase of steel fiber content, the compressive strength loss of NSPC decreased first and then increased after F-T cycles. The use of steel fiber enhanced the integrality inside the APCs of NSPC and reduced the APC clogging rate, which improved hydraulic-conductivity properties after F-T cycles. After 300 F-T cycles, NSPC with 2% steel fiber achieved an excellent rainstorm waterlogging resistance (stagnant water depth of 0 mm), regardless of the rainstorm return period. Through F-T damage analysis, in order to cope with waterlogging, the maximum FT failure thresholds of NSPC to prevent stagnant water of 50, 70 and 100 mm are 0.097, 0.125 and 0.161 respectively, equivalent to 196, 243 and 264 F-T cycles. This study designed a NSPC that can dissipate stagnant water after F-T cycles, which provided a promising route towards solving urban rainstorm waterlogging.

Mimicking the Shape and Function of the ClC Chloride Channel Selective Pore by Combining a Molecular Hourglass Shape with Anion-π Interactions.

ClC is the main family of natural chloride channel proteins that transport Cl- across the cell membrane with high selectivity. The chloride transport and selectivity are determined by the hourglass-shaped pore and the filter located in the central and narrow region of the pore. Artificial unimolecular channel that mimics both the shape and function of the ClC selective pore is attractive, because it could provide simple molecular model to probe the intriguing mechanism and structure-function relevance of ClC. Here we elaborated upon the concept of molecular hourglass plus anion-π interactions for this purpose. The concept was validated by experimental results of molecular hourglasses using shape-persistent 1,3-alternate tetraoxacalix[2]arene[2]triazine as the central macrocyclic skeleton to control the conductance and selectivity, and anion-π interactions as the driving force to facilitate the chloride dehydration and movement along the channel.

Experimental Study on Scouring and Silting and Channel Planning Based on the Entrance Area of Shenqiu Wharf

China has a vast territory and a long history of inland navigation. This paper is based on the Shaying River Shenqiu hub project, and a normal physical model with a geometric scale of 65 was established to simulate the characteristics of water and sediment in the entrance area of the project. By setting different working conditions and measuring and analyzing the velocity flow pattern of the wharf area, planning suggestions for the artificial channel with straight cut-off can be given. Simultaneously, the study simulates the natural sediment deposition state in typical years, observing changes in terrain and evaluating their impact on navigation, thereby validating the rationality of scouring and desilting processes. The research findings indicate that in the reconstructed river wharf’s entrance area, the flow velocity is low, and the flow pattern is stable, ensuring that the transverse flow velocities along the recommended route meet the requirements for vessel navigation. Post-scouring from the regulating gate discharge, downstream deposition decreases, with a sediment flushing efficiency reaching 68.5%. Under the specified conditions, the thickness of sediment deposition after scouring does not negatively affect the water level for ships entering or departing the wharf. The results of this study may offer valuable reference insights for the planning of artificial rivers in similar terrains.

Self-cascade deoxynivalenol detoxification by an artificial enzyme with bifunctions of dehydrogenase and aldo/keto reductase from genome mining

Due to the severe health risks for human and animal caused by the intake of toxic deoxynivalenol (DON) derived from Fusarium species, elimination DON in food and feed has been initiated as a critical issue. Enzymatic cascade catalysis by dehydrogenase and aldo-keto reductase represents a fascinating strategy for DON detoxification. Here, one quinone-dpendent alcohol dehydrogenase DADH oxidized DON into less-toxic 3-keto-DON and NADPH-dependent aldo-keto reductase AKR13B3 reduced 3-keto-DON into relatively non-toxic 3-epi-DON were identified from Devosia strain A6-243, indicating that degradation of DON on C3 are two-step sequential cascade processes. To establish the bifunctions, fusion enzyme linking DADH and AKR13B3 was successfully assembled to promote one-step DON degradations with accelerated specific activity and efficiency, resulting 93.29 % of DON removal rate in wheat sample. Three-dimensional simulation analysis revealed that the bifunctional enzyme forms an artificial intramolecular channel to minimize the distance of intermediate from DADH to AKR13B3 for two-step enzymatic reactions, and thereby accelerates this enzymatic process. As the first report of directing single step DON detoxification by an interesting bifunctional artificial enzyme, this work revealed a facile and eco-friendly approach to detoxify DON with application potential and gave valuable insights into execute other mycotoxin detoxification for ensuring food safety.

PERANCANGAN JALUR SALURAN DRAINASE GUNA MENANGGULANGI BANJIR PADA PERUMAHAN WARGA

In the area of Jl. RE. Soemantadiredja No.351, Palasari, Kec. Cijeruk, Bogor Regency, West Java, drainage channel is a water outlet that is located below or above the surface naturally or artificially. This housing does not have a water outlet, so when it rains the moving water cannot pass and causes flooding in the area, because the water discharge is getting higher, the existing wall between community settlements & housing collapses leads to community settlements, agricultural land, and livestock. Public. After carrying out site management, we found a solution to the flood problem by making a drainage link for flood water disposal that leads to the pond, to prevent landslides in the community's rice fields, it is necessary to build water channels made of materials in line with the emergency artificial river channels made by society.

Quickest detection of bias injection attacks on the glucose sensor in the artificial pancreas under meal disturbances

Modern glucose sensors deployed in closed-loop insulin delivery systems, so-called artificial pancreas use wireless communication channels. While this allows a flexible system design, it also introduces vulnerability to cyberattacks. Timely detection and mitigation of attacks are imperative for device safety. However, large unknown meal disturbances are a crucial challenge in determining whether the sensor has been compromised or the sensor glucose trajectories are normal. We address this issue from a control-theoretic security perspective. In particular, a time-varying Kalman filter is employed to handle the sporadic meal intakes. The filter prediction error is then statistically evaluated to detect anomalies if present. We compare two state-of-the-art online anomaly detection algorithms, namely the χ2 and CUSUM tests. We establish a robust optimal detection rule for unknown bias injections. Even if the optimality holds only for the restrictive case of constant bias injections, we show that the proposed model-based anomaly detection scheme is also effective for generic non-stealthy sensor deception attacks through numerical simulations.

A sunflower-pith-based robust and efficient evaporator with enclosed cellular structure and ultralow vaporization enthalpy for round-the-clock steam generation

Solar interfacial evaporation (SIE) is a promising method to generate freshwater from unconventional water resources. Using hydrogel materials to activate water molecules has been demonstrated as a facile way to achieve high SIE performance. However, as for hydrogel and hydrogel-analogous evaporators, there is a trade-off between SIE performance and mechanical property due to their high water content and porous structure. Herein, we demonstrate a low-cost and robust sunflower-pith-based hydrogel-like evaporator by simple dip-coating and soaking process. The rigid cellular framework and water encapsulated inside endow this evaporator with excellent compressive strength, which achieves 400.3 ± 64.1 KPa at compressive strain of 80 %. In the meantime, natural ultralow water vaporization enthalpy and ability to capture thermal energy from surroundings enable this evaporator to achieve an outstanding water evaporation rate of 3.39 kg·m−2·h−1 with an energy efficiency of 100.2 % under 1 sun. Moreover, this evaporator exhibits a potential for round-the-clock operation since its evaporation rate can reach 1.14 kg·m−2·h−1 in dark. After introducing artificial open channels, this evaporator shows remarkable stability and durability even for 20 wt% brine. This work provides a sustainable choice for efficient desalination and freshwater production, and offers a guideline for the bionic design of SIE materials.

Unveiling the transport of water and ions in the nanocage of zeolitic imidazolate frameworks by molecular dynamics

Precise ion/water and ion/ion separation requires pores of size closely aligned with the dimension of filtering molecules or ions. Zeolitic imidazolate frameworks (ZIFs), a class of porous crystallizes with well-defined Å ngstrom pores and diverse structures, making them promising candidates for nanofluidic channels. In this work, we perform molecular simulations to explore the structures and kinetics of water and ions confined in 4 typical ZIFs, including ZIF-65, ZIF-8, SALEM-2 and ZIF-Cl. Our findings reveal that the structure of water molecules within these ZIFs closely resembles that of bulk water but two diffusion regimes are identified. Notably, the diffusion coefficients (D) of the water are one order of magnitude lower than bulk water while the order of D for different ZIFs cannot be simply attributed to steric effects. The ion diffusion barriers exhibit a distinct contrast between monovalent and divalent cations, closely mirroring ion-valence selectivity as biological channels. Additionally, the Å ngstrom-scale pores within ZIFs demonstrate exceptional capability of filtering alkali metal ions with the selectivity as high as 10–100. Further analysis underscores the substantial effects of pore flexibility. The comprehensive simulation results strongly indicate that ZIFs hold significant promise for utilization in development of artificial ion channels and precise ion separation membranes.