Environmental Impact of Artificial Harbors in Tropic Pacific Oceanic Islands

For loading and unloading of boats or ships round the clock, the access channel and its expanded part-a port are excavated on the lagoon and ocean reef flats in the tropic Pacific oceanic islands. Without moles, the access channel port traps sediment and further transports it to the ocean or lagoon, resulting in coastal erosion. The wide uneven reef flat with a large catchment area tends to cause the formation of tide currents in the channel port, while strong waves on the narrow even reef flat can give rise to rip currents. An access channel port with a mole on one side or two moles on both sides results in less erosion. A model is recommended as an artificial harbor on the ocean coast, which is an excavated port surrounded by a mole, connected with the ocean by an access channel and with the shore by a bridge shaped pier.

Artificial Water Channels—Progress Innovations and Prospects

The design of artificialwater channels(AWCs)aims to mimic natural proteins that effectively mediate the selective transport of water across the bilayer and artificial polymeric membranes.Currently,impressive progress on synthetic backbones,including selfassembled channels,helical unimolecular,and other functional organic molecules,has been made to provide artificial alternatives and applications in real systems for promising product development.In this review,several synthetic channels exploited during the last fewyears are summarized according to their backbone architecture for water transport and ion transport respectively,showing their potential as natural transporter analogs and the importance of AWCs for industrial,environmental,and medical applications.

Pore Characteristic Design Method of High-strength Pervious Concrete Based on the Mechanical Properties and Rainstorm Waterlogging Resistance

High-strength pervious concrete(HSPC) with porosity ranging from 0.08% to 2.011% was prepared. The mechanical properties and rainstorm waterlogging resistance of HSPC were evaluated,and a design method of HSPC pore characteristics(porosity and pore diameter) based on the mechanical properties and rainstorm waterlogging resistance was proposed. The results showed that the reduction of effective cross-sectional area caused by artificial channels was the main factor affecting flexural strength but had limited influence on compressive strength. Compared with the concrete matrix without artificial channels,the compressive strength of HSPC with porosity of 2.011% decreased by 7.4%, while the flexural strength decreased by 48.3%. The permeability coefficient of HSPC can reach 16.35 mm/s even at low porosity(2.011%).HSPC can meet the requirements of no rainstorm waterlogging, even if exposed to 100-year rainstorms. When the mechanical properties and rainstorm waterlogging resistance are compromised, the recommended porosity ranges from 1.1% to 3.5%, and the recommended pore diameter ranges from 0.8 to 2.7 mm.

Self-assembled Supramolecular Artificial Transmembrane Ion Channels:Recent Progress and Application

Natural protein channels have evolved with fantastic spatial structures,which play pivotal physiological functions in all living systems.Learning from nature,chemical scientists have developed a myriad of artificial transmembrane ion channels by using various chemical strategies,among which the non-covalent supramolecular ion channels exhibit remarkable advantages over other forms(e.g.,single-molecule ion channel),which exhibited facile preparation methods,easier structural modification and functionalization.In this review,we have systematically summarized the recent progress of supramolecular self-assembled artificial transmembrane ion channels,which were classified by different self-assembly mechanisms,such as hydrogen bonds,π-πinteractions,etc.Detailed preparation process and self-assembly strategies of the supramolecular ion channels have been described.Moreover,potential biomedical applications of the supramolecular ion channels have also been carefully discussed in this review.Finally,future opportunities and challenges facing this field were also elaborately discussed.It is anticipated that this review could provide a panoramic sketch and future directions towards the construction of novel artificial ion channels with novel functions and biomedical applications.

Highly active artificial potassium channels having record-high K^(+)/Na^(+) selectivity of 20.1

Replicating extraordinarily high membrane transport selectivity of protein channels in artificial channel is a challenging task.In this work,we demonstrate that a strategic application of steric code-based social self-sorting offers a novel means to enhance ion transport selectivities of artificial ion channels,alongside with boosted ion transport activities.More specifically,two types of mutually compatible sterically bulky groups(benzo-crown ether and tert-butyl group)were appended onto a monopeptide-based scaffold,which can order the bulky groups onto the same side of a one-dimensionally aligned H-bonded structure.Strong steric repulsions among the same type of bulky groups(either benzo-crown ethers or tert-butyl groups),which are forced into proximity by H-bonds,favor the formation of hetero-oligomeric ensem-bles that carry an alternative arrangement of sterically compatible benzo-crown ethers and tert-butyl groups,rather than homo-oligomeric ensembles containing a single type of either benzo-crown ethers or tert-butyl groups.Coupled with side chain tuning,this social self-sorting strategy delivers highly ac-tive hetero-oligomeric K+-selective ion channel(5F12-BF12)_(n),displaying the highest K+/Na+selectivity of 20.1 among artificial potassium channels and an excellent ECso value of 0.50μmol/L(0.62 mo1%relative to lipids)in terms of single channel concentration.

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

Actin 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.

Investigating Ion Transport through Artificial Transmembrane Channels Containing Introverted Groups

The investigation on the relationship between structure and transport activity of artificial transmembrane channels has still re-mained a challenge because of lacking strategy to precisely arrange the functional group in the channel structures.Herein,we report a general strategy to monitor ion transport through the artificial channels by using unimolecular tubular molecules containing intro-verted groups.We found that the ion transport rate decreased with elongation of the introverted sidechains and the channel with propyl group as the introverted sidechain exhibited the longest opening duration time.Moreover,we have revealed that,comparing to the ion transport rate,the opening duration is a more important factor for determining the transport activity of the artificial channels.

Causes of Land Loss in Tuvalu,a Small Island Nation in the Pacific

Studies on land loss in Tuvalu reveal the following findings. Although both sea level rise and coastal erosion can cause land loss in the tropic Pacific oceanic islands, their mechanisms are different. When sea level rises, the low elevation coastal zone submerges and the erosion datum plane rises, the beach process progresses normally as always, resulting in no beach sediment coarsening. When the sea level is stable, coastal erosion removes finer sediment from reef flat, beach and land, resulting in beach sediment coarsening. The human-induced coastal erosion in the tropic Pacific oceanic islands has the following features. 1) Erosion occurs or intensifies immediately after inappropriate human activities. 2) It occurs near the places having human activities and places related to the above places in sediment supply. 3) It often occurs on original prograding or stable coasts (on lagoon coasts for atolls) because there are more coastal engineering projects and other human activities on such coasts. 4) It is chronic, covering a long period of time. The coastal geological events in Tuvalu islands do not accord with the features resulted from sea level rise but do accord with the features resulted from coastal erosion, particularly from human-induced erosion. The land loss in Tuvalu is mainly caused by inappropriate human activities including coastal engineering and aggregate mining, and partly caused by cyclones. Moreover, all recent measurements (satellite altimetry,thermosteric sea level data and tide observations) so far have not been able to verify any sea level rise around Tuvalu islands.

Artificial Water Channel that Couples with Cell Protrusion Formation

In natural systems,water transport across the cellular plasma membranes is mainly mediated by naturally occurring channel protein aquaporins(AQPs),which lead to a series of important physiological functions including cell migration.The construction of artificial analogs of the natural AQPs would generate a new strategy for treating AQP-related diseases.In this report,an artificial water channel has been developed from a unimolecular tubular molecule,which featured structural encapsulation of a single-file water wire composed of oppositely orientated dipolar water molecules.This AQP-like structure endowed the artificial channel in living cells with AQP-like water permeability and selectivity.Interestingly,the artificial channel coupled with cell protrusion formation by mediating water transmembrane transport,leading to cell shape change and migration acceleration.The artificial channel-facilitated cell migration showed application in enhancing in vivo healing of traumatic injury.

Artificial neural-network-based visible light positioning algorithm with a diffuse optical channel

Visible light positioning becomes popular recently. However, its performance is degraded by the indoor diffuse optical channel. An artificial neural-network-based visible light positioning algorithm is proposed in this Letter, and a trained neural network is used to achieve positioning with a diffuse channel. Simulations are made to evaluate the proposed positioning algorithm. Results show that the average positioning error is reduced about 13 times, and the positioning time is reduced about two magnitudes. Moreover, the proposed algorithm is robust with a different field-of-view of the receiver and the refiectivity of the wall, which is suitable for various position- ing applications.

Unimolecular Transmembrane Na^(+) Channels Constructed by Pore-Forming Helical Polymers with a 2.3A Aperture

To understand the relationships between channel size and ion selectivity,we have developed a new type of artificial ion channel based on pore-forming helical polymers consisting of phenanthrolineoxadiazole units with a pore aperture 2.3A close to the diameter of the Na^(+)ion(2.04A).Successful preparation of high molecular weight helical polymers(HP1)gives rise to a 4.6 nm long artificial unimolecular transmembrane channel.The transport property of artificial channel HP1 was elaborately investigated by means of vesicle-based kinetic assay and symmetry/asymmetry bilayer membrane(BLM)experiments as well.These results unambiguously demonstrate that HP1 is a Na^(+)-selective channel with extremely high transport activity(EC_(50)=0.017 mol% relative to lipid).Moreover,the Na^(+)/K^(+)selectivity ratio of HP1 reaches 1.9,as determined by asymmetry BLM experiments.Owing to the narrowest 2.3A size constraint so far,HP1 transport naked Na^(+)ion across the membrane,which represents a different Na^(+)transport mode from that of natural Na^(+)channels,which transports partially hydrated Na^(+)ions during transmembrane conduction.This study provides crucial insights on the chemical basis of ion selectivity in the field of ion channels.

Unimolecular artificial transmembrane channel with terminal dihydrogen phosphate groups showing transport selectivity for ammonium

A new artificial transmembrane channel molecule bearing dihydrogen phosphate groups has been synthesized.The terminal dihydrogen phosphate groups enable the channel to be highly negatively charged at both ends of the channel structures.The artificial channel could incorporate into the lipid bilayer efficiently under low concentration.The channel displays high NH4+/K+selectivity due to the electrostatic interaction and hydrogen bonding between NH4+and the terminal dihydrogen phosphate groups.

Porous metal-organic cage-based membranes

As a new class of porous solid materials with structural variability,notable porosity,and good dispersibility,metal-organic cages(MOCs)have shown great promise as filler components for separation membranes.Research into MOC-based membranes has blossomed over the last decade because of their high performance in separation,desalination,and artificial channel.In this review,we summarize current membranes based on MOCs including mixed matrix membranes,cross-linked membranes,composite membranes,bilayer lipid membranes,and liquid membranes,and provide a brief overview of their applications.The challenges and opportunities in future developments are also discussed.

Molecular rotaxane shuttle-relay accelerates K^(+)/Cl^(-) symport across a lipid membrane

Synthetic molecules that can mediate the coupled transport of Cl^(-) with K^(+) and/or Na+across the lipid bilayers have aroused great interest due to their potential as a novel therapeutic strategy by disrupting cellular ion homeostasis.Based on the structural advantages of molecular rotaxanes,we herein show that two rotaxane-based transporters[2]R and[3]R induce coupled K^(+)/Cl^(-) channel transport by introducing Cl^(-) recognition sites in the thread and K^(+) binding group in the wheel,respectively.The welldesigned molecular structures allow the insertion of unimolecular rotaxanes into the lipid bilayer,thus achieving effective ion transport by means of thermodynamically controlled movement and driven by the difference in ion concentration inside and outside the vesicles.In addition,the use of a three-component rotaxane can accelerate ion transport through a cooperative shuttlerelay mechanism in which two wheels move along the thread in the lipid membrane,thereby enabling[3]R to have higher ion transport capacity.This work represents a major advance in the use of rotaxane molecules to accomplish more complex and effective tasks.

Bioinspired and biomimetic membranes for water purification and chemical separation: A review

Bioinspired and biomimetic membranes that contain biological transport channels or attain their structural designs from biological systems have been through a remarkable development over the last two decades.They take advantage of the exceptional transport properties of those channels,thus possess both high permeability and selectivity,and have emerged as a promising solution to existing membranes.Since the discovery of biological water channel proteins aquaporins(AQPs),extensive efforts have been made to utilize them to make separation membranes–AQP-based membranes,which have been commercialized.The exploration of AQPs’unique structures and transport properties has resulted in the evolution of biomimetic separation materials from protein-based to artificial channelbased membranes.However,large-scale,defect-free biomimetic membranes are not available yet.This paper reviews the state-of-the-art biomimetic membranes and summarizes the latest research progress,platform,and methodology.Then it critically discusses the potential routes of this emerging area toward scalable applications.We conclude that an appropriate combination of bioinspired concepts and molecular engineering with mature polymer industry may lead to scalable polymeric membranes with intrinsic selective channels,which will gain the merit of both desired selectivity and scalability.