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.

Research progress on the water vapor channel within the Yarlung Zsangbo Grand Canyon, China

The Second Tibetan Plateau Scientific Expedition and Research Program tasked a research team with the“Investigation of the water vapor channel of the Yarlung Zsangbo Grand Canyon(INVC)”in the southeastern Tibetan Plateau(TP).This paper summarizes the scientific achievements obtained from the data collected by the INVC observation network and highlights the progress in investigating the development of heavy rainfall events associated with water vapor changes.The rain gauge network of the INVC can represent the impacts of the Yarlung Zsangbo Grand Canyon(YGC)topography on precipitation at the hourly scale.The microphysical characteristics of the precipitation in the YGC are different than those in the lowland area.The GPM-IMERG(Integrated MultisatellitE Retrievals for Global Precipitation Measurement)satellite precipitation data for the YGC region should be calibrated before they are used.The meridional water vapor flux through the YGC is more important than the zonal flux for the precipitation over the southeastern TP.The decreased precipitation around the YGC region is partly due to the decreased meridional water vapor flux passing through the YGC.High-resolution numerical models can benefit precipitation forecasting in this region by using a combination of specific schemes that capture the valley wind and water vapor flux along the valley floor.

Water Channels Are Involved in Stomatal Oscillations Encoded by Parameter-Specific Cytosolic Calcium Oscillations

Earlier studies have shown that various stimuli can induce specific cytosolic calcium （[Ca^2＋]cyt） oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca^2＋]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean （Vicia faba L.） was used and a rapid ion-exchange treatment with two shifting buffers differing in K^＋ and Ca^2＋ concentrations was applied. The treatment for fivetransients at a 10-min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some Irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation Is encoded by parameter-specific [Ca^2＋]cyt oscillation： the parameters of [Ca^2＋]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely Inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β-mercaptoethanol （an agent capable of reversing water channel inhibition by HgCl2）. Other Inhibitory treatments against Ion transport （i.e. the application of LaCIs, EGTA, or tetraethylammonlum chloride （TEACI）） weakly impaired stomatal oscillation when the compounds were added after rapid ion-exchange treatment. If these compounds were added before rapid-ion exchange treatment, the inhibitory effect was much more apparent （except In the case of TEACI）. The results of the present study suggest that water channels are involved In stomatal oscillation as a downstream element of [Ca^2＋]cyt oscillation signaling.

The role of water channel proteins and nitric oxide signaling in rice seed germination

Previous studies have demonstrated the possible role of several aquaporins in seed germination. But systematic investigation of the role ofaquaporin family members in this process is lacking. Here, the developmental regulation of plasma membrane intrinsic protein （PIP） expression throughout germination and post-germination processes in rice embryos was analyzed. The expression patterns of the PIPs suggest these aquaporins play different roles in seed germination and seedling growth. Partial silencing of the water channel genes, OsPIP1;1 and OsPIP1：3, reduced seed germination while over-expression of OsPIP1：3 promoted seed germination under water-stress conditions. Moreover, spatial expression analysis indicates that OsPIP1：3 is expressed predominantly in embryo during seed germination. Our data also revealed that the nitric oxide （NO） donors, sodium nitroprusside （SNP） and S-nitrosoglutathione （GSNO）, promoted seed germination; furthermore, the NO scavenger, 2-（4-carboxyphenyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, inhibited germination and reduced the stimulative effects of SNP and GSNO on rice germination. Exogenous NO stimulated the transcription of OsPIP1：1, OsPIP1：2, OsPIP1：3 and OsPIP2：8 in germinating seeds. These results suggest that water channels play an important role in seed germination, acting, at least partly, in response to the NO signaling pathway.

Comment on: Cloning and characterization of porcine aquaporin 1 water channel expressed extensively in the gastrointestinal system

TO THE EDITOR Sir, I read with great interest the recently published article in the World Journal of Gastroenterology by Jin and co-workers on the cloning and characterization of porcine aquaporin 1 water channel from the pig liver and studies on its expression in the porcine gastrointestinal system. The authors should be congratulated for making this important and valuable contribution to the field of aquaporin biology and porcine gastrointestinal physiology. However, there are a number of unresolved issues and controversies concerning the expression of aquaporins （especially aquaporin 1） in the gastrointestinal system that are worthy of additional comment and discussion by Jin and co-workers.

The structure and dynamics of water inside armchair carbon nanotube

In this paper we present some simulation results about the behaviour of water molecules inside a single wall carbon nanotube （SWNT）. We find that the confinement of water in an SWNT can induce a wave-like pattern distribution along the channel axis, similar phenomena are also observed in biological water channels. Carbon nanotubes（CNTs） can serve as simple nonpolar water channels. Molecular transport through narrow CNTs is highly collective because of tight hydrogen bonds in the protective environment of the pore. The hydrogen bond net is important for proton and other signal transports. The average dipoles of water molecules inside CNTs （7,7）, （8,8） and （9,9） are discussed in detail. Simulation results indicate that the states of dipole are affected by the diameter of SWNT. The number of hydrogen bonds, the water-water interaction and water-CNT interaction are also studied in this paper.

Some Physiological Processes Related to Water Use Efficiency of Higher Plants

Water use efficiency （WUE） of higher plants is of vital importance in the dry-land agricultural ecosystem in terms of the development of water-saving agriculture. Of all the approaches used to improve WUE, the intrinsic water use efficiency （WUET, the ratio of CO2 assimilation rate to transpiration rate） can be a right index, as the variation of WUET is correlated with the physiological and biochemical processes of higher plants. The measurements of leaf gas exchange and carbon isotope discrimination （D^13C） are the two ways to detect the variation in WUEr. This article reviewed some physiological processes related to WUEv, including the relationship between CO2 assimilation and stomatal conductance and WUET and water absorption. The relationship between WUE and aquaporin and the yield are discussed as well.

Uncertainty Analysis for Ship-Bank Interaction Tests in A Circulating Water Channel

This paper presents a systematic model test program to assess the uncertainty of the ship-bank interaction forces,using the planar motion mechanism(PMM)system in a circulating water channel(CWC).Therefore,the uncertainties due to ship-bank distance and water depth are considered,and they are calculated via the partial differentials of the regression formulae based on the test data.The general part of the uncertainty analysis(UA)is performed according to the ITTC recommended procedure 7.5-02-06.04,while the uncertainty of speed is identified as the bias limit due to the flow velocity maldistribution in the CWC.In each example test for the UA of ship-bank interaction forces,12 repeated measurements were conducted.Results from the UA show that the contribution of water depth error and flow velocity maldistribution to the total uncertainty is noticeable,and the paper explains how they increase with the change of the test conditions.The present study will be useful in understanding the uncertainty regarding the ship-bank interaction force measurement in a CWC.

NUMERICAL AND EXPERIMENTAL STUDY OF LURE MOVING IN WATER

The motion of a lure in water is investigated experimentally and numerically.The lure motion in water of apassing water tank is observed,and the periodic motion is found.From the Fourier analysis,it is found that the frequency with the largest amplitude in the lateral direction depends on the lip width of the lure.To understand the lure dynamics,a numerical simulation of the flow field around the lure is performed.The shape is measured using an X-ray computer tomography and converted into a voxel model.From visualization,it is found that vortex sheds from its lip correspond to the vibration frequency of the lure.

Distribution of chlorophyU a and estimation of primary productivity in the eastern waters of Balingtang Channel in summer

Oceanographical features on both sides of Balingtang Channel (17°55′-20°06′N, 122°55′-126°57′E) were comprehensively investigated on board of R/V "Experiment 3" in June. 1984. The pre-sent paper reports the chlorophyll data collected and primary productivity estimated there. Water sam-ples were taken with a glass bottle of Model HQMat the depth of 0, 10. 25, 50, 75, 100 and 150m, separately. Chlorophyll was determined according to the spectrophotometry proposed by UNESCO(1966) and calculated with the trichromatic equations of Jeffrey-Humphrey(1975). Estimations ofprimary productivity were carried out using a simplified equation (Q = 1.5) given by Cadee(1975).

Inter-comparison of the Infrared Channels of the Meteorological Imager Onboard COMS and Hyperspectral IASI Data

The successful launch and commissioning of the first geostationary meteorological satellite of Korea has the potential to enhance earth observation capability over the Asia Pacific region. Although the specifications of the payload, the mete- orological imager （MI）, have been verified during both ground and in-orbit tests, there is the possibility of variation and/or degradation of data quality due to many different reasons, such as the accumulation of contaminants, the aging of instrument components, and unexpected external disturbance. Thus, for better utilization of MI data, it is imperative to continuously monitor and maintain the data quality. As a part of such activity, this study presents an inter-calibration, based on the Global Space-based Inter-Calibration System （GSICS）, between the MI data and the high quality hyperspectral data from the In- frared Atmospheric Sounding Interferometer （IASI） of the Metop-A satellite. Both sets of data, acquired for three years from April 2011 to March 2014, are processed to prepare the matchup dataset, which is spatially collocated, temporally concurrent, angularly coincident, and spectrally comparable. The results show that the MI data are stable within the specifications and show no significant degradation during the study period. However, the water vapor channel shows a rather large bias value of -0.77 K, with a root-mean-square difference （RMSD） of around 1.1 K, which is thought to be due to the shift in the spectral response function. The shortwave channel shows a maximum RMSD of around 1.39 K, mainly due to the coarse digitization at the lower temperature. The inter-comparison results are re-checked through a sensitivity analysis with different sets of threshold values used for the matchup dataset. Based on this, we confirm that the overall quality of the MI data meets the user requirements and maintains the expected performance, although the water vapor channel requires further investigation.

Relationship between adjustment of low water level and utilization of water depth in Shashi Reach in middle Yangtze River

Hydrological,sediment,and bathymetric data of the Shashi Reach in the middle Yangtze River for the period of 1975-2018 were collected,and the characteristics of low water level changes and their impacts on utilization of water depth for navigation were investigated.The results showed that,during the study period,the Shashi Reach riverbed was significantly scoured and incised,with cross-sectional profiles showing overall narrowing and deepening.This indicated a strong potential to improve the water depth of the channel.The analysis of the temporal variation of in-channel topographical features showed that the Taipingkou diara underwent siltation and erosion,with its head gradually scoured and relocated downstream after 2008,and the Sanbatan diara continued to shrink and migrate leftwards.Low water levels with the same flow rate over the study period decreased.For instance,from 2003 to 2020,the water level at the Shashi hydrological station decreased to 1.37 m with a flow rate of 6000 m^(3)/s.Furthermore,the designed minimum navigable water level of the Shashi Reach was approximately 2.11m lower than the recommended level.In terms of utilization of the channel water depth,continuous scouring of the river channel is expected to result in a reduction in discharge at the Taipingkou mouth,which will improve the water depth conditions of the channel during the dry season in the Shashi Reach.With several channel regulation projects,the 3.5-m depth of the Shashi Reach would basically be unobstructed.This promotes utilization of the shipping route from the Taipingkou south branch to the Sanbatan north branch as the main navigation channel during the dry season.Considering the factors of current water depth and the clear width limitation of the navigation hole at the Jingzhou Yangtze River Bridge,this route can still be favored as the main navigation channel with a 4.5-m depth during the dry season.

Prospects for High-quality Development of Water Resources

The water resources of rivers and reservoirs with a five-meter drop are used to discuss the technical theory and the cost and practical value of equipment cases.The high-quality development technology of water resources explored in this paper provides a feasible plan for achieving the goal of innovation to zero.

Well-structured 3D channels within GO-based membranes enable ultrafast wastewater treatment

Graphene oxide(GO)-based membranes have been widely studied for realizing efficient wastewater treatment,due to their easily functionalizeable surfaces and tunable interlayer structures.However,the irregular structure of water channels within GO-based membrane has largely confined water permeance and prevented the simultaneously improvement of purification performance.Herein,we purposely construct the well-structured three-dimensional(3D)water channels featuring regular and negatively-charged properties in the GO/SiO_(2)composite membrane via in situ close-packing assembly of SiO_(2)nanoparticles onto GO nanosheets.Such regular 3D channels can improve the water permeance to a record-high value of 33,431.5±559.9 L·m^(−2)·h−1(LMH)bar−1,which is several-fold higher than those of current state-of-the-art GO-based membranes.We further demonstrate that benefiting from negative charges on both GO and SiO2,these negatively-charged 3D channels enable the charge selectivity well toward dye in wastewater where the rejection for positive-charged and negative-charged dye molecules is 99.6%vs.7.2%,respectively.The 3D channels can also accelerate oil/water(O/W)separation process,in which the O/W permeance and oil rejection can reach 19,589.2±1,189.7 LMH bar−1 and 98.2%,respectively.The present work unveils the positive role of well-structured 3D channels on synchronizing the remarkable improvement of both water permeance and purification performance for highly efficient wastewater treatment.

循环水通道阻塞效应对自主水下航行器水动力系数估算的影响

The Reynolds-averaged Navier–Stokes(RANS)equation was solved using computational fluid dynamics to study the effect of the circulating tank wall on the hydrodynamic coefficient of an autonomous underwater vehicle(AUV).Numerical results were compared with the experimental results in the circulating water tank of Harbin Engineering University.The numerical results of the model with different scale ratios under the same water in the flume were studied to investigate the effect of blockage on the hydrodynamic performance of AUV in the circulating flume model test.The results show that the hydrodynamic coefficient is stable with the scale reduction of the model.The influence of blocking effect on AUV is given by combining theoretical calculation with experiment.

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.

Aquaporins in spermatozoa and testicular germ cells： identification and potential role

Mammalian spermatozoa have relatively high water permeability and swell readily, as in the hypo-osmotic swelling test used in the andrology clinic. Physiologically, spermatozoa experience changes in the osmolality of the surrounding fluids in both the male and the female tracts on their journey from the testis to the ovum. Sperm volume regulation in response to such osmotic challenges is important to maintain a stable cell size for the normal shape and function of the sperm tail. Alongside ion channels for the fluxes of osmolytes, water channels would be crucial for sperm volume regulation. In contrast to the deep knowledge and numerous studies on somatic cell aquaporins （AQPs）, the understanding of sperm AQPs is limited. Among the 13 AQPs, convincing evidence for their presence in spermatozoa has been confined to AQP7, AQP8 and AQP 11. Overall, current findings indicate a major role of AQP8 in water influx and efltux for sperm volume regulation, which is required for natural fertilization. The preliminary data suggestive of a role for AQP7 in sperm glycerol metabolism needs further substantiation. The association of AQP 11 with the residual cytoplasm of elongated spermatids and the distal tail of spermatozoa supports the hypothesis of more than just a role in conferring water permeability and also in the turnover and recycling of surplus cellular components made redundant during spermiogenesis and spermiation. This would be crucial for the maintenance of a germinal epithelium functioning efficiently in the production of spermatozoa.

Enhanced Expression of Aquaporin-9 in Rat Brain Edema Induced by Bacterial Lipopolysaccharides

To investigate the role of AQP9 in brain edema, the expression of AQP9 in an infectious rat brain edema model induced by the injection of lipopolysaccharide （LPS） was examined. Immuno- histochemistry and reverse transcription-polymerase chain reaction （RT-PCR） analysis demonstrated that the expressions of AQP9 mRNA and protein at all observed intervals were significantly increased in LPS-treated animals in comparison with the control animals. Time-course analysis showed that the first signs of blood-brain barrier disruption and the increase of brain water content in LPS-treated animals were evident 6 h after LPS injection, with maximum value appearing at 12 h, which coincided with the expression profiles of AQP9 mRNA and protein in LPS-treated animals. The further correlation analysis revealed strong positive correlations among the brain water content, the disruption of the blood-brain barrier and the enhanced expressions of AQP9 mRNA and protein in LPS-treated animals. These results suggested that the regulation of AQP9 expression may play im- portant roles in water movement and in brain metabolic homeostasis associated with the pathophysi- ology of brain edema induced by LPS injection.

Physical Experiments to Investigate the Effects of Street Bottom Heating and Inflow Turbulence on Urban Street-Canyon Flow

The effects of street bottom heating and inflow turbulence on urbanstreet-canyon flow are experimentally investigated using a circulating water channel. Threeexperiments are carried out for a street canyon with a street aspect ratio of 1. Results from eachexperiment with bottom heating or inflow turbulence are compared with those without bottom heatingand appreciable inflow turbulence. It is demonstrated that street bottom heating or inflowturbulence increases the intensity of the canyon vortex. A possible explanation on how street bottomheating or inflow turbulence intensifies the canyon vortex is given from a fluid dynamicalviewpoint.

Enhancing the hydration reactivity of hemi-hydrate phosphogypsum through a morphology-controlled preparation technology

The distribution of water channels in the crystal morphology of type-α hemi-hydrated gypsum(α-HH) was theoretically detected to investigate the effect of water channels on the hydration reactivity of hemi-hydrate phosphogypsum(HPG). Results showed that water channels were mainly distributed in the cylinders of α-HH crystal,whereas no water channel existed in the conical surfaces parallel to the z-axis. Increasing the number of water channels was critical to enhance the hydration activity of HPG compared with the hydration reactivity of industrial HPG and type-α high-strength gypsum. Controlling the technological parameters of crystallization by concentration of liquid-phase SO_4^(2-) made it possible to obtain HPG which had the stumpy crystals of α-HH and high hydration reactivity.