Channel Modification Research Articles

Two classic mutations in the linker‐helix IIL45 and segment IIS6 of Apolygus lucorum sodium channel confer pyrethroid resistance

Pyrethroids are classified as type I and type II for distinct symptomology. Voltage-gated sodium channel is a primary target of pyrethroids. Mutations of the insect sodium channel have been identified to result in resistance to pyrethroids. Double mutation (L1002 F/M906 I) was detected in field-strain of Apolygus lucorum (Meyer-Dür). Although, it was illuminated the function of the same position mutation in other pests, it is necessary to demonstrate the role in A. lucorum . In this study, we examined the effects of mutations on channel gating and pyrethroid sensitivity in Xenopus oocytes. L1002 F, M906 I and L1002 F/M906 I all shifted the voltage dependence of activation in the depolarizing direction. L1002 F, M906 I and L1002 F/M906 I all reduced the amplitude of tail currents induced by type I (bifenthrin and permethrin) and type II (λ-cyhalothrin and deltamethrin). The double mutation, L1002 F/M906 I, reduced integral channel modification by 10-fold compared with the L1002 F and M906 I mutations alone, respectively. Computational analysis based on the model of dual pyrethroid receptors, the two resistance mutations, L1002 F and M906 I are facing two opposite sides of this newly identified pocket. Both mutations affect the optimal binding of the ligands by changing the shape of the pocket but in different ways. Our results illustrate the distinct effect of mutations on pyrethroids. It is predicted with computer modeling that these mutations allosterically affect pyrethroid binding. © 2020 Society of Chemical Industry.

Energy-exergy and enviro-economic survey of solar air heaters with various air channel modifications

Abstract Solar air heaters (SAHs) are generally used in different applications because of their simple structure, low setup cost, and also their higher energy conversion efficiency. In this study, a v-groove type SAH (VTPSAH) has been developed, manufactured and compared with parallel-pass SAH (PPSAH) and double-pass SAH (DPSAH) under same climatic conditions. In addition to the experimental analysis, CFD simulation of SAHs has been done to investigate heat and flow behavior inside the systems. The experiments have been performed in 0.015 kg/s, 0.013 kg/s and 0.011 kg/s mass flow rates on February and June to evaluate the performance of SAHs at various climatic conditions. According to the obtained results, annual average thermal efficiency for PPSAH, DPSAH and VTPSAH were obtained as 54–60.29%, 61.86–66.95% and 70.91–78.18%. The maximum instantaneous thermal efficiency was achieved in all tests as 90.65% in highest mass flow rate in VTPSAH in February. Exergy efficiency values for VTPSAH, DPSAH and PPSAH were obtained in the range of 14.62–18.95%, 12.28–15.68% and 6.68–9.74%, respectively. Moreover, Enviro-economic costs were found between 4.22 and 7.66 $/year. Also, the highest deviation between numerical and experimental results is 10%.

Macroinvertebrate metrics responses to morphological alteration in Italian rivers

The responses of river macroinvertebrates to hydromorphological alteration are often considered weak or unclear. It is therefore crucial to verify if and how existing invertebrate-based approaches can reveal the effects of hydromorphological modification. We analyzed the responses of benthic metrics to morphological impairment, with emphasis on the STAR_ICM index, legally required for macroinvertebrate-based ecological status assessment in Italy. A Principal Component Analysis (PCA) was run to condense information on morphological impairment. The major gradient (Component 1) expressed a combination of bank and channel modifications opposed to tree-related features indicating the presence of comparatively unmodified habitats. Jointly, habitat descriptors including Habitat Modification Score (HMS) derived from the application of a habitat survey method were calculated. Spearman rank correlations between biological metrics and morphological impairment indicators (PCA scores and HMS) were significant. A linear mixed-effects regression approach was applied to relate HMS and STAR_ICMi across a wide geographical context. HMS explained > 60% of STAR_ICMi variability, in the absence of apparent water pollution. Results demonstrated that morphological information resumed with habitat survey methods is meaningful for the biological community and that HMS can support the interpretation of ecological status across rivers’ types and in different environmental settings.

Modelbuilder and Unit Hydrograph for Flood Prediction and Watershed Flow Direction Determination at The West Branch of The Little River, Stowe, Lamoille County, Vermont, USA

The West Branch of the Little River in Stowe, Lamoille County, Vermont has been widely studied, and this area is regularly subject to flooding. The West Branch joins the Little River, which flows into the Winooski and drains into Lake Champlain. This area has undergone extensive development as an economic response to the ski resort industry over the past 50 years, and the recreational pathway is on the banks of the river. The Little River is adjusting to the loss of historic floodplain area, channel modifications (straightening and gravel mining), and runoff changes. In this project, a DEM with 10 and 30 meters resolution will be used to determine the watershed area for the outlet point at the south of Stowe for hydrological analysis. This project intends to describe the watershed flow direction with a unit hydrograph that shows when water discharge at the outlet is at its height during a rainfall event and produce the floods prediction map by predicting the nature of flood events to help in planning and responding to flood events effectively using ArcGIS Pro 2.0. The results show the time it takes water to flow to the outlet ranges from 0 seconds (rain that falls on the outlet itself) to over 8 hours and 46 minutes. The amount of water has accumulated, indicating that water will flow at its fastest when funneling toward the outlet point downstream of the town with no exception, indicating that water will flow at its fastest when funneling toward the outlet point downstream of the town.

Alternatives of flood control for the Linei river, city of Toboali (a case study of the Rawabangun region)

Rawabangun is one of the areas in the City of Toboali in South Bangka Regency that is often flooded. There is a main river that passes through the Rawabangun area, which is the Linei River. The aim of this study is to analyse alternatives that can be used in flood control in Rawabangun. The analysis was carried out with the 5.1 Storm Water Management Model (SWMM) and 5-year planned rainfall. There were 9 overflow points found on the channel, and the implementation of flood control is to be carried out with infiltration wells, retention ponds, and channel modification. The application of infiltration wells with a maximum of 1267 units can eliminate 8 overflow points. The application of 3 units of retention ponds with a maximum of 3 units can eliminate 5 overflow points. Changing the channel depth to 4 m can eliminate all overflow points but is not relevant to be applied.

Influence of anthropogenic landscape modifications and infrastructure on the geological characteristics of liquefaction

Abstract Many large cities worldwide are built on natural and engineered geological materials that are highly susceptible to liquefaction and associated ground failure in earthquakes. Constitutive equations describing relationships between sediment geotechnical characteristics, seismological parameters, and liquefaction susceptibility of natural and engineered sediments are well established. What is less understood is the role of anthropogenic landscape modifications (e.g., river channel modifications, sediment engineering and re-distribution) and infrastructure (e.g., buildings, buried infrastructure such as drainage systems) on the spatial distributions and severity of liquefaction and ground deformation. Here we use stratigraphic studies, ground penetrating radar (GPR), and analyses of high-resolution aerial photographs to evaluate surface and subsurface geological manifestations of recurrent liquefaction in anthropogenically-modified landscapes during the 2010–2011 Canterbury earthquake sequence in New Zealand. Engineered fill layers provided low density, high permeability traps that captured fluidized sediment and promoted the formation of a unique assemblage of liquefaction-induced sediment intrusions that differ from those preserved in proximal natural sediment. Subsurface drainage systems imparted significant influence on the location, size and orientations of liquefaction ejecta features. Sediments adjacent to engineered stream channels experienced large lateral strains that are unlikely to have occurred in the absence of channel modifications. Spatial variations in naturally-formed topography and liquefaction-susceptible sediments exerted strong influence on the characteristics of liquefaction hazards, even in highly engineered environments. Collectively, these observations highlight important interactions between natural and engineered environments that should be carefully considered when interpreting the geologic effects of contemporary earthquakes and / or using prehistoric geological records to forecast future hazards.

Impact of Riparian and Stream Restoration on Denitrification in Geomorphic Features of Agricultural Streams

HighlightsDenitrification enzyme activity (DEA) was measured in stream sediments of restored and unrestored agricultural streams.Nitrate, sediment characteristics, riparian vegetation, and geomorphology influenced DEA.Pools at restored sites had lower organic carbon, coarser sediment textures, and lower denitrification potential.Restoration strategies should increase organic carbon and residence times through complex flowpaths.Abstract. Agricultural land use, channel modifications, and riparian vegetation composition can affect instream denitrification by altering geomorphic features, such as sediment texture, organic matter, retention time, and hyporheic exchange. Stream and riparian restoration is widely implemented in agricultural watersheds to mitigate excess nutrient export to sensitive downstream waters; however, the cumulative impact of channel reconstruction and altered channel and near-stream morphology on nitrogen dynamics remains poorly understood. We measured denitrification enzyme activity (DEA) and environmental variables (e.g., water chemistry, sediment texture, and organic matter) in different geomorphic features in agriculturally influenced streams in North Carolina with varied channel and riparian zone characteristics. Our results indicate that denitrification is primarily influenced by increased transport of nitrate (NO3-) to the streams in wetter months. Secondarily, structural factors, including riparian vegetation and stream geomorphology, impact denitrification by controlling the distribution of sediment texture and organic carbon. In the newly restored stream, we observed coarser streambed sediments and low sediment organic carbon, especially in scour pools constructed downstream from cross-vanes. Lower DEA was observed in restored pools (39.1 ng N g-1 dry mass h-1) compared to naturally occurring pools (70.7 to 278.1 ng N g-1 dry mass h-1). These results highlight the need for restoration strategies to be directed at increasing organic carbon and residence times through complex flowpaths (e.g., meanders, root wads, artificial woody debris dams). Keywords: Denitrification, Freshwater, Nitrogen, Restoration, Riparian, Stream, Water quality.

A Waterbody Typology Derived from Catchment Controls Using Self-Organising Maps

Multiple catchment controls contribute to the geomorphic functioning of river systems at the reach-level, yet only a limited number are usually considered by river scientists and managers. This study uses multiple morphometric, geological, climatic and anthropogenic catchment characteristics to produce a single national typology of catchment controls in England and Wales. Self-organising maps, a machine learning technique, are used to reduce the complexity of the GIS-derived characteristics to classify 4485 Water Framework Directive waterbodies into seven types. The waterbody typology is mapped across England and Wales, primarily reflecting an upland to lowland gradient in catchment controls and secondarily reflecting the heterogeneity of the catchment landscape. The seven waterbody types are evaluated using reach-level physical habitat indices (including measures of sediment size, flow, channel modification and diversity) extracted from River Habitat Survey data. Significant differences are found between each of the waterbody types for most habitat indices suggesting that the GIS-derived typology has functional application for reach-level habitats. This waterbody typology derived from catchment controls is a valuable tool for understanding catchment influences on physical habitats. It should prove useful for rapid assessment of catchment controls for river management, especially where regulatory compliance is based on reach-level monitoring.

Prioritizing management goals for stream biological integrity within the developed landscape context

Stream management goals for biological integrity may be difficult to achieve in developed landscapes where channel modification and other factors constrain in-stream conditions. To evaluate potential constraints on biological integrity, we developed a statewide landscape model for California that estimates ranges of likely scores for a macroinvertebrate-based index that are typical at a site with the observed level of landscape alteration. This context can support prioritization decisions for stream management, like identifying reaches for restoration or enhanced protection based on how observed scores relate to model predictions. Median scores were accurately predicted by the model for all sites in California with bioassessment data (Pearson correlation r = 0.75 between observed and predicted for calibration data, r = 0.72 for validation). The model also predicted that 15% of streams statewide are constrained for biological integrity within their present developed landscape, particularly for urban and agricultural areas in the South Coast, Central Valley, and Bay Area regions. We worked with a local stakeholder group from the San Gabriel River watershed (Los Angeles County, California) to evaluate how the statewide model could support local management decisions. To achieve this purpose, we created an interactive application, the Stream Classification and Priority Explorer, that compares observed scores with predictions from the landscape model to assign priorities. We observed model predictions consistent with the land-use gradient from the upper to lower watershed, where potential limits to achieving biological integrity were more common in the heavily-urbanized lower watershed. However, most of the sites in the lower watershed scored within their predicted ranges, and were therefore given a low priority for restoration. In contrast, 2 low-scoring sites in the undeveloped upper watershed were prioritized for causal assessment and possible future restoration, whereas 3 high-scoring sites were prioritized for protection. The availability of geospatial and bioassessment data at the national level suggests that these tools can easily be applied to inform management decisions at other locations where altered landscapes may limit biological integrity.

Brook trout (Salvelinus fontinalis) movement and survival after removal of two dams on the West Branch of the Wolf River, Wisconsin

AbstractDam removals allow fish to access habitats that may provide ecological benefits and risks, but the extent of fish movements through former dam sites has not been thoroughly evaluated for many species. We installed stationary PIT antennas in 2016 and 2017 to evaluate movements and survival of brook trout Salvelinus fontinalis in the West Branch of the Wolf River (WBWR) in central Wisconsin following removal of two dams and channel modifications designed to promote fish movement. These changes provided access to lacustrine habitats that might provide suitable winter habitat or act as ecological sinks. We used multistate models to estimate transition probabilities between river sections, to determine whether brook trout: (a) moved between multiple river sections and (b) entered lacustrine habitats as seasonal refuges, but eventually returned to lotic habitat. We also used a Cormack‐Jolly‐Seber model to evaluate whether apparent survival of brook trout in the WBWR was comparable to other populations. Few fish moved among river sections or used lacustrine habitat (<5% of tagged fish); most brook trout remained in sections where they were initially tagged, potentially due to quality habitat located throughout the river. Like other studies, brook trout in the WBWR appear to experience high mortality based on low number of detections, few physical recaptures and an estimated eight‐month apparent survival rate of 0.27. In scenarios where fish can already access suitable habitat, removal of dams may not result in substantial increases in fish movement and colonisation of newly accessible habitat may not occur immediately.

Regulating ENaC's gate.

Epithelial Na+ channels (ENaCs) are members of a family of cation channels that function as sensors of the extracellular environment. ENaCs are activated by specific proteases in the biosynthetic pathway and at the cell surface and remove embedded inhibitory tracts, which allows channels to transition to higher open-probability states. Resolved structures of ENaC and an acid-sensing ion channel revealed highly organized extracellular regions. Within the periphery of ENaC subunits are unique domains formed by antiparallel β-strands containing the inhibitory tracts and protease cleavage sites. ENaCs are inhibited by Na+ binding to specific extracellular site(s), which promotes channel transition to a lower open-probability state. Specific inositol phospholipids and channel modification by Cys-palmitoylation enhance channel open probability. How these regulatory factors interact in a concerted manner to influence channel open probability is an important question that has not been resolved. These various factors are reviewed, and the impact of specific factors on human disorders is discussed.

Non-genomic effects of steroid hormones: role of ion channels

In animals, steroid hormones can act using genomic and non-genomic mechanisms. Plant steroid hormones, brassinosteroids, are capable of inducing the expression of some gene ensembles, however their non-genomic pathways for triggering the physiological effects are still unclear. In this paper, we propose the hypothesis on existence of brassinosteroid non-genomic effects in plant cells. This non-genomic pathway could due to modulation of ion channel activities and modification of membrane receptors.

Fabricating better metal-organic frameworks separators for Li–S batteries: Pore sizes effects inspired channel modification strategy

More and more researchers have realized the pores within metal-organic frameworks (MOFs) can suppress polysulfides shuttling and improve the performance of Li–S batteries. However, neither the initial “sulfur loss”, nor the related exacerbated voltage polarizations have raised enough attentions. Herein, these issues have been rationally demonstrated by the interactions between polysulfides and metal sites inside MOFs pores, and the sluggish lithium ions transportation pathway which are closely related to metal sites and pore sizes within MOFs. Moreover, as a channel modification strategy, decorating MOF channels with negatively charged sulfonic polymer (NSP) can concurrently turn the charge environment of the MOF channels (by forming sulfurphobic interaction between polysulfides and NSP) and facilitate the transportation of lithium ions, resulting in greatly relieved initial “sulfur loss” and largely reduced voltage polarizations of Li–S batteries. Simultaneously narrow the MOF channels and turn the charge environment of the MOF channels reveled a win-win situation, which we anticipate will provide a rational design strategy for fabricating functional MOFs used as membranes and even solid electrolytes for various energy storage systems.

Design of Monolithic Supports by 3D Printing for Its Application in the Preferential Oxidation of CO (CO-PrOx)

Honeycomb-shaped cordierite monoliths are widely used as supports for a large number of industrial applications. However, the high manufacturing cost of cordierite monoliths only justifies its use for high temperatures and aggressive chemical environments, demanding applications where the economic benefit obtained exceeds the manufacturing costs. For low demanding applications, such as the preferential oxidation of CO (CO-PrOx), alternative materials can be proposed to reduce manufacturing costs. Polymeric monoliths would be an interesting low-cost alternative; however, the limitations of the active phase incorporation to the polymeric support must be overcome. In this work, the implementation and use of polymeric monolithic structures obtained by three-dimensional printing to support CuO/CeO2 catalysts for CO-PrOx have been studied. Several approaches were used to anchor the active phase into the polymeric monoliths, such as adding inorganic materials (carbon or silica) to the polymer previous to the printing process, chemical attack with solvents of the printed resin before or during the active phase incorporation, and consecutive impregnation and modification of the channel wall design. Among those approaches, best results were obtained by the addition of silica and by channel modification. Independent of the strategy followed, a subsequent thermal treatment in N2 was required to soften the resin and favor the active phase anchoring. However, catalyst particles become embedded on the polymeric resin being not active, and thus, a final cleaning thermal treatment under air was needed to recover the active phase activity, after which the supported active phase demonstrated good catalytic activity, stability, and reusability.

How alternative urban stream channel designs influence ecohydraulic conditions

Streams draining urban catchments ubiquitously undergo negative physical and ecosystem changes, recognized to be primarily driven by frequent stormwater runoff input. The common management intervention is rehabilitation of channel morphology. Despite engineering design intentions, ecohydraulic benefits of urban channel rehabilitation are largely unknown and likely limited. This investigation uses an ecohydraulic modeling approach to investigate the performance of alternative channel design configurations intended to restore key ecosystem functioning in urban streams. Channel reconfiguration design scenarios, specified to emulate the range of channel topographic complexity often used in rehabilitation are compared against a reference ‘natural’ scenario using ecologically relevant hydraulic metrics. The results showed that the ecohydraulic conditions were incremental improved with the addition of natural oscillations to an increasing number of individual topographic variables in a degraded channel. Results showed that reconfiguration reduced excessive frequency of bed mobility, loss of habitat and hydraulic diversity particularly as more topographic variables were added. However, the results also showed that none of the design scenarios returned the ecohydraulics to their reference conditions. This indicate that channel-based restoration can offer some potential changes to hydraulic habitat conditions but are unlikely to completely mitigate the effects of hydrologic change. We suggest that while reach-scale channel modification may be beneficial to restore urban stream, addressing altered hydrology is critical to fully recover natural ecosystem processes.

Loss of Potential Aquatic-Terrestrial Subsidies Along the Missouri River Floodplain

The floodplains of large rivers have been heavily modified due to riparian development and channel modifications, both of which can eliminate shallow off-channel habitats. The importance of these habitats for aquatic organisms like fishes is well studied. However, loss of off-channel habitat also eliminates habitats for the production of emerging aquatic insects, which subsidize riparian consumers in terrestrial food webs. We used field collections of insect emergence, historical mapping, and statistical modeling to estimate the loss of insect emergence due to channel modifications along eight segments of the Missouri River (USA), encompassing 1566 river km, between 1890 and 2012. We estimate annual production of emerging aquatic insects declined by a median of 36,000 kgC (95% CrI: 3000 to 450,000) between 1890 and 2012 (a 34% loss), due to the loss of surface area in backwaters and related off-channel habitats. Under a conservative assumption that riparian birds obtain 24% of their annual energy budget from adult aquatic insects, this amount of insect loss would be enough to subsidize approximately 790,000 riparian woodland birds during the breeding and nesting period (May to August; 95% CrI: 57,000 to 10,000,000). Most of the loss is concentrated in the lower reaches of the Missouri River, which historically had a wide floodplain, a meandering channel, and a high density of off-channel habitats, but which were substantially reduced due to channelization and bank stabilization. Our results indicate that the loss of off-channel habitats in large river floodplains has the potential to substantially affect energy availability for riparian insectivores, further demonstrating the importance of maintaining and restoring these habitats for linked aquatic-terrestrial ecosystems.

A New Payload Partition Strategy in Color Image Steganography

In traditional steganographic schemes, RGB three channels payloads are assigned equally in a true color image. In fact, the security of color image steganography relates not only to data-embedding algorithms but also to different payload partition. How to exploit inter-channel correlations to allocate payload for performance enhancement is still an open issue in color image steganography. In this paper, a novel channel-dependent payload partition strategy based on amplifying channel modification probabilities is proposed, so as to adaptively assign the embedding capacity among RGB channels. The modification probabilities of three corresponding pixels in RGB channels are simultaneously increased, and thus the embedding impacts could be clustered, in order to improve the empirical steganographic security against the channel co-occurrences detection. The experimental results show that the new color image steganographic schemes, incorporated with the proposed strategy, can effectively make the embedding changes concentrated mainly in textured regions, and achieve better performance on resisting the modern color image steganalysis.

Atomic-scale identification of crystalline GaON nanophase for enhanced GaN MIS-FET channel

In this work, we demonstrate an easy channel-engineering method using oxygen-plasma treatment followed by in-situ annealing before gate dielectric deposition on GaN. A crystalline GaON nanophase was identified to serve as an optimized channel layer in the gate region of E-mode GaN metal-insulator-semiconductor field-effect transistors (MIS-FETs). The atomic-scale element distribution and crystalline structure of the GaON nanophase were revealed by aberration-corrected scanning transmission electron microscopy. First-principles calculations further correlate the enhanced thermal stability with the atomic observation of the refined structure in the GaON nanophase. Owing to the atomically sharp gate-dielectric/channel interface and low interface trap density (Dit), the boosted performance of the E-mode MIS-FET was achieved with the GaON channel. This study not only validates an approach of local channel modification for high-performance normally off GaN MIS-FETs but also opens possibilities of utilizing this crystalline GaON nanophase as a promising channel material in various GaN devices.

Bigger Tides, Less Flooding: Effects of Dredging on Barotropic Dynamics in a Highly Modified Estuary

AbstractSince the late nineteenth century, channel depths have more than doubled in parts of New York Harbor and the tidal Hudson River, wetlands have been reclaimed and navigational channels widened, and river flow has been regulated. To quantify the effects of these modifications, observations and numerical simulations using historical and modern bathymetry are used to analyze changes in the barotropic dynamics. Model results and water level records for Albany (1868 to present) and New York Harbor (1844 to present) recovered from archives show that the tidal amplitude has more than doubled near the head of tides, whereas increases in the lower estuary have been slight (<10%). Channel deepening has reduced the effective drag in the upper tidal river, shifting the system from hyposynchronous (tide decaying landward) to hypersynchronous (tide amplifying). Similarly, modeling shows that coastal storm effects propagate farther landward, with a 20% increase in amplitude for a major event. In contrast, the decrease in friction with channel deepening has lowered the tidally averaged water level during discharge events, more than compensating for increased surge amplitude. Combined with river regulation that reduced peak discharges, the overall risk of extreme water levels in the upper tidal river decreased after channel construction, reducing the water level for the 10‐year recurrence interval event by almost 3 m. Mean water level decreased sharply with channel modifications around 1930, and subsequent decadal variability has depended both on river discharge and sea level rise. Channel construction has only slightly altered tidal and storm surge amplitudes in the lower estuary.

Fish community response to in-channel woody debris in a channelized river system

Additions of large wood (LW) have become a go-to technique for recovering altered river ecosystems. However, successful applications of this technique are generally limited to unchannelized rivers and headwater streams. Channelization of rivers, that is, engineering river channels to reduce recruitment and retention of in-channel structure, may, by definition, limit success of this restoration technique. Moreover, sufficient time has passed (a century or more) since initial channelization of many large rivers that portions of the fish community associated with LW may have become extirpated. Thus, the maxim that LW leads to a positive fish community response may not hold true. We examined fish community associations in habitats with and without LW in the channelized Missouri River to gain an understanding of the role of LW in large, channelized rivers. There were some differences between habitats with wood present compared to those without, but the differences were not evident once year, season and channel modifications intended to create aquatic habitat were taken into account. We assert that careful planning is necessary to ensure that additions of LW in channelized rivers are made to appropriate locations such that it will be retained in-channel for use as fish habitat and that LW-associated species are found in the system.