Impermeable Barrier Research Articles

Brain-targeted delivery of Valsartan using solid lipid nanoparticles labeled with Rhodamine B; a promising technique for mitigating the negative effects of stroke

The brain is a vital organ that is protected from the general circulation and is distinguished by the presence of a relatively impermeable blood brain barrier (BBB). Blood brain barrier prevents the entry of foreign molecules. The current research aims to transport valsartan (Val) across BBB utilizing solid lipid nanoparticles (SLNs) approach to mitigate the adverse effects of stroke. Using a 32-factorial design, we could investigate and optimize the effect of several variables in order to improve brain permeability of valsartan in a target-specific and sustained-release manner, which led to alleviation of ischemia-induced brain damage. The impact of each of the following independent variables was investigated: lipid concentration (% w/v), surfactant concentration (% w/v), and homogenization speed (RPM) on particle size, zeta potential (ZP), entrapment efficiency (EE) %, and cumulative drug release percentage (CDR) %. TEM images revealed a spherical form of the optimized nanoparticles, with particle size (215.76 ± 7.63 nm), PDI (0.311 ± 0.02), ZP (-15.26 ± 0.58 mV), EE (59.45 ± 0.88%), and CDR (87.59 ± 1.67%) for 72 hours. SLNs formulations showed sustained drug release, which could effectively reduce the dose frequency and improve patient compliance. DSC and X-ray emphasize that Val was encapsulated in the amorphous form. The in-vivo results revealed that the optimized formula successfully delivered Val to the brain through intranasal rout as compared to a pure Val solution and evidenced by the photon imaging and florescence intensity quantification. In a conclusion, the optimized SLN formula (F9) could be a promising therapy for delivering Val to brain, alleviating the negative consequences associated with stroke.

Nanoparticle-Based Techniques for Bladder Cancer Imaging: A Review

Bladder cancer is very common in humans and is often characterized by recurrences, compromising the patient's quality of life with a substantial social and economic impact. Both the diagnosis and treatment of bladder cancer are problematic due to the exceptionally impermeable barrier formed by the urothelium lining the bladder; this hinders the penetration of molecules via intravesical instillation while making it difficult to precisely label the tumor tissue for surgical resection or pharmacologic treatment. Nanotechnology has been envisaged as an opportunity to improve both the diagnostic and therapeutic approaches for bladder cancer since the nanoconstructs can cross the urothelial barrier and may be functionalized for active targeting, loaded with therapeutic agents, and visualized by different imaging techniques. In this article, we offer a selection of recent experimental applications of nanoparticle-based imaging techniques, with the aim of providing an easy and rapid technical guide for the development of nanoconstructs to specifically detect bladder cancer cells. Most of these applications are based on the well-established fluorescence imaging and magnetic resonance imaging currently used in the medical field and gave positive results on bladder cancer models in vivo, thus opening promising perspectives for the translation of preclinical results to the clinical practice.

Determination of water permeability through stress-free lipid membranes using time-resolved small angle neutron scattering.

The lipid bilayer, the basic unit of biological membranes, is an essentially impermeable barrier. Because of this, the environment inside the cell can be significantly different from the environment surrounding it, such as pH, ion compositions and biomolecular concentrations. Since several cellular functions require the fast transport of large or charged molecules through the membrane, the cell membrane contains specialized proteins that specifically transport these across the membrane. Notwithstanding permeation happens via passive diffusion as well. This type of transport, we imagine, is slow, even for small molecules, such as water. Indeed, the cell has active water transporters (aquaporin) to move water through its membranes faster. The time and energy required to move water across the lipid bilayer passively is still debated, however. Several techniques have been used to measure water permeation such as NMR, fluorescence, and micropipetting. Here we take advantage of contrast between H2O and D2O to investigate, through time-resolved SANS, the water permeability of stress-free membranes composed of different saturated lipids. The principle is to follow the scattering intensity of a hydrogenated vesicle solution, initially prepared in H2O, when diluted with D2O. The resulting changes in scattering are a result of the intake of D2O into the vesicle's interior without any induced stress on the membrane. Our results show that water permeation in membranes in the gel state is faster, by at least an order of magnitude, than previously reported. The water permeation changes due to cholesterol in liquid ordered phases is also discussed.

Use of Silica Fume, Bentonite, and Waste Tire Rubber as Impermeable Layer Construction Materials

To avoid the potential risks associated with all hazardous wastes, it is important that containment methods are intended to prevent the migration of liquid hazardous wastes or leaks containing hazardous components. Therefore, impermeable barriers were used to prevent contamination. In this study, geotechnical tests were performed on samples by mixing rubber and bentonite with silica fume at certain percentages. The aim of the experimental studies is to evaluate the applicability of certain proportions of silica fume, rubber, and bentonite mixtures as impermeable liner material. Possible cracks in bentonite during drying are reduced by the use of silica fume. Absorption of dynamic effects that may occur on the impermeable barrier layer is achieved by adding waste rubber in a uniform size. Several geotechnical tests were performed to examine the mixed rubber and bentonite with silica fumes. Looking at the results of the whole that mixed rubber and bentonite with silica fume yielded usable results and a blend for construction of a liner.

A semi-analytical solution for water wave scattering by partially immersed perforated and solid barriers with a quadratic pressure discharge condition

Partially immersed perforated and/or solid barriers in the ocean are often considered as important components of many marine applications, and they have received significant attentions by ocean engineering research community with potential flow methods. In this study, water wave interaction with a system that consists of a vertical perforated front barrier and a vertical impermeable rear barrier, as a representative unit, is investigated based on the linear potential flow theory. A semi-analytical solution for this problem is derived using an eigenfunction expansion method and an iterative resolution method. To model the flow passing through the perforated barrier, a quadratic pressure discharge condition of practical validity is applied. The reflection coefficient predicted by the present analytical model agrees well with the published theoretical result. The validated model is used to perform a parametric study to examine the effects of the width, submergence depth, porosity, incident wave steepness and wave frequency on the hydrodynamic characteristics of the perforated system. It is found that larger incident wave steepness can result in smaller transmission coefficient and dimensionless horizontal wave force acting on the impermeable rear barrier and larger dimensionless horizontal wave force acting on the perforated front barrier due to the nonlinear nature of the quadratic pressure discharge condition. By examination over a broad range of circumstances, we find that the partially immersed perforated system is more effective when the ratio of the width to the incident wavelength B/L is located between 0.2+0.5n and 0.35+0.5n (n=1,2,…). The present study can be utilized for a range of marine applications in wave preventing and wave energy absorption or conversion.

Sustained release of alginate hydrogel containing antimicrobial peptide Chol-37(F34-R) in vitro and its effect on wound healing in murine model of Pseudomonas aeruginosa infection.

Antibiotic resistance is a significant public health concern around the globe. Antimicrobial peptides exhibit broad-spectrum and efficient antibacterial activity with an added advantage of low drug resistance. The higher water content and 3D network structure of the hydrogels are beneficial for maintaining antimicrobial peptide activity and help to prevent degradation. The antimicrobial peptide released from hydrogels also hasten the local wound healing by promoting epithelial tissue regeneration and granulation tissue formation. This study aimed at developing sodium alginate based hydrogel loaded with a novel antimicrobial peptide Chol-37(F34-R) and to investigate the characteristics in vitro and in vivo as an alternative antibacterial wound dressing to treat infectious wounds. Hydrogels were developed and optimized by varying the concentrations of crosslinkers and subjected to various characterization tests like cross-sectional morphology, swelling index, percent water contents, water retention ratio, drug release and antibacterial activity in vitro, and Pseudomonas aeruginosa infected wound mice model in vivo. The results indicated that the hydrogel C proved superior in terms of cross-sectional morphology having uniformly sized interconnected pores, a good swelling index, with the capacity to retain a higher quantity of water. Furthermore, the optimized hydrogel has been found to exert a significant antimicrobial activity against bacteria and was also found to prevent bacterial infiltration into the wound site due to forming an impermeable barrier between the wound bed and external environment. The optimized hydrogel was found to significantly hasten skin regeneration in animal models when compared to other treatments in addition to strong inhibitory effect on the release of pro-inflammatory cytokines (interleukin-1β and tumor necrosis factor-α). Our results suggest that sodium alginate -based hydrogels loaded with Chol-37(F34-R) hold the potential to be used as an alternative to conventional antibiotics in treating infectious skin wounds.

Evaluating melting gel coatings for wearable metabolic sensors

New steps have been taken toward finalizing a novel wearable sensor for entirely non-invasive, continuous blood sugar monitoring via the low concentrations of acetone continuously emitted from human skin as a byproduct of metabolic activity. This sensor is based on a chemo-mechanical actuating polymer composite of the well-known conducting polymer polyaniline and cellulose acetate, which is a simple derivative of the incredibly proliferous and benign organic compound cellulose. The improvements reported here revolve around the application of a 65% methyltriethoxysilane – 35% dimethyldiethoxysilane melting gel to one side of the sensor, thereby isolating the sensor from ambient air and any interferents it might contain. Visual inspection shows that the melting gel does not prohibit functionality of the existing polyaniline-cellulose acetate sensor, and FTIR spectroscopy shows that no significant chemical changes are caused by application of the melting gel to the polyaniline-cellulose acetate sensor. • Composite-material wearable metabolic sensors continuously monitor skin-gas emissions. • Novel sensors are chemo-mechanical actuating polyaniline-cellulose acetate composite. • Organically modified siloxane melting gels create impermeable hydrophobic barrier. • Melting gel coatings are applied and consolidated without damaging composite sensors.

Leachate Characterization Generated from Municipal Solid waste at Landfill Site Ghazipur, New Delhi

Abstract: The management of municipal solid waste (MSW) is one of the key environmental issues facing Indian cities, mostly as a result of the country's growing industrialisation and urbanisation. According to numerous studies, open dumps and landfills are used to dispose of around 90% of solid waste in an improper manner. Pollutants can escape a poorly constructed landfill in a number of ways. Leachate can escape from a landfill or dumpsite and contaminate groundwater and surface water if the soil above or below it is porous. Therefore, In this paper an attempt is made to characterize the leachate produced by municipal solid waste dumping site of Ghazipur, New Delhi which is located at Latitude: 28° 37' 30.8784". Longitude: 77° 19' 40.764" near the Delhi-UP border. In this investigation, about 12 leachate parameters were identified. Three sample sites at the bottom of the landfill, spaced 7 metres apart, were used to characterise the leachate samples. All of the leachate samples had an acidic pH value ranging from 6.24 to 6.88, it is discovered. All of the sample’s conductivity and total dissolved solids ranged from 567 to 1945 S/cm and 513 to 1289 ppm respectively. Similar dissolved ions such chloride, calcium, sodium, nitrate, and potassium were found in the leachate sample. The majority of the ions were discovered to be above the standards-permitted level. The present study concludes that characterization of landfill leachate is important to identify the most critical pollutants present in the leachate and thereby to introduce suitable and applicable technologies such as in-situ impermeable barriers etc.

Electrical Shorting of Thermocouples in Flexible Thermal Protection System Materials

The flexible thermal protection system (FTPS) on NASA’s Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) vehicle will be instrumented with thermocouples to measure the in-depth thermal response during entry into Earth’s atmosphere. Accurate flight temperature measurements are critical for verifying vehicle performance during the flight test and reducing uncertainties in the thermal models, but the deployable nature of inflatable decelerator technology presents challenges. The thermocouples need to be compactable, cannot damage the FTPS or the inflatable structure, and need to be able to withstand high temperatures and large thermal gradients. The present paper details the developmental testing that was performed using a tube furnace to examine the potential error sources associated with instrumenting NASA’s FTPS with thermocouples insulated with either glass braid or ceramic braid. Large measurement errors occurred with both thermocouple insulation materials due to conductive deposits on the insulation electrically shorting the thermocouple leads. Two mechanisms were identified that contribute to this phenomenon: 1) the organic binder on the thermocouple insulation carbonizes in a high-temperature, low-oxygen environment and 2) decomposition products from the FTPS are able to permeate the braided insulation. The effect of heat cleaning the thermocouples to eliminate the first mechanism is presented, and the possibility of using a mica wrap as an impermeable barrier to mitigate the second mechanism is explored. Finally, the applicability of the ground-based tube furnace test results to the flight environment is discussed.

Something New about Radial Wave Functions of Fermions in the Repulsive Coulomb Field

An impermeable barrier at $r=r_{cl}$ in the effective potential of the relativistic Schr\"odinger-type equation leads to exclusion of the range $0 \leq r < r_{cl}$ from the wave function domain. Based on duality of the Schr\"odinger-type equation and the Dirac equation, a similar exclusion should be made in the wave functions domain of the Dirac equation. As a result, we obtain new solutions to the Dirac equation in the Coulomb repulsive field. Calculations show that depending on working parameters, at distances of several fractions or units of the Compton wavelength of the fermion from $r=r_{cl}$ new solutions almost coincide with the standard Coulomb functions of the continuous spectrum. Practically, matrix elements with new solutions will coincide to a good accuracy with standard matrix elements with the Coulomb functions of the continuous spectrum. Our consideration is methodological and helpful for discussing further development of quantum theory.

Spray coating for washout tooling by binder jet additive manufacturing

Washout tooling is a process in which a removable mold or fixture is disintegrated using a solvent. Binder Jet (BJ) additive manufacturing holds promise for creating customized washout molds from common materials. BJ-based washout tooling provides an advanced strategy in manufacturing fiber-reinforced composites (FRCs), especially for customized hollow FRCs. However, washout tools formed by BJ require an impermeable barrier between the porous tooling surface and the parts laid up on the surface to prevent the resin from infiltrating the tooling surface and bonding the tool to the FRC. The conventional method for preventing resin migration into the washout mold from the FRC is winding Teflon® tape over the entire surface, which is labor-intensive and very difficult to deploy for specific geometries. Here, we report the development of a polymer spray coating method to seal the tooling surface and prevent resin infiltration without affecting the washout properties needed for sacrificial tooling. Two water-soluble polymers, poly(sodium 4-styrenesulfonate) (PSS–Na) and poly(vinylsulfonic acid, sodium salt) (PVS–Na), were investigated for spray coating. PVS-Na maintained tighter geometric tolerances and provided excellent thermal stability with the onset of decomposition at 320 °C and glass transition temperature of 280 °C. Spray coating with PVS-Na streamlines the process of forming a protective layer for the washout molds by BJ, reduces migration of the resins from the FRC, and significantly improves the production efficiency of complex washout tools.

An insight into simultaneous phase transition phenomena and melt-rheology of low-density polyethylene/ethylene–vinyl acetate copolymer/expanded graphite nanocomposites through continuous extrusion foaming process

In the present article, the influences of expanded graphites (EGs) with small, medium, and large aspect ratios (SEG, MEG, and LEG, respectively) on the foamability of low-density polyethylene (LDPE)/ethylene–vinyl acetate copolymer (EVA) blend obtained from continuous extrusion foaming process were studied. The addition of EGs to the PE/EVA blend resulted in foams with smaller cells and higher cell densities. Among the different nanofillers used, EG with larger aspect ratio caused the formation of PE/EVA foams with higher void fraction, smaller cell size and larger cell density. EG nanoplatelets assisted bubble nucleation and acted as an impermeable barrier against the gas removal from the melt, where LEG behaved more successfully due to having a larger surface area with the melt. During the bubble nucleation and growth stages, PE/EVA liquid–liquid and solid–liquid phase separations took place concurrently. The presence of EG nanofillers influenced the PE/EVA phase separation and increased the mutual solubility of the polymeric constituents in each other. Besides, EG nanolayers enhanced the viscoelastic properties of PE/EVA melt, and thus prevented cell wall rupture and gas release from the melt.

Brain-Targeted Drug Delivery System: A Novel Approach

A targeted drug delivery system is based on a technique that continuously administers a predetermined dosage of a therapeutic agent to a sick location of the body. The targeted drug delivery goal is to raise the relative amount of the treatment in the target tissues while lowering it in the non-target tissues. This technique's intrinsic benefit has been reduced drug dose and adverse effects. Drug targeting in the brain is one of the most challenging issues in pharmaceutical research because the blood-brain barrier acts as an impermeable barrier for systemically delivered therapeutics and the brain extracellular matrix contributes to the poor distribution of locally delivered drugs. In the treatment of various Central nervous system (CNS) diseases, general approaches that can improve drug delivery to the brain are of great interest. Drugs are less harmful and more effective when they are administered close to where they would be most effective. Extreme research studies have recently concentrated on the development of fresh strategies for more successfully delivering medications to the brain in response to the shortcomings of the traditional delivery mechanism. This study thoroughly explains the obstacles involved in brain-targeted drug delivery, the process of drug transfer through Blood Brain Barrier, different techniques for brain-targeted drug delivery, and some recent breakthroughs in brain-targeted drug delivery.&#x0D; Keywords: Blood-brain barrier, Brain-targeted, Cerebrospinal fluid, Nanoparticles, Liposomes, Convection-enhanced drug delivery.

Advancement in microneedles as minimally invasive delivery system for pharmaceutical and biomedical application: A review

Microneedle expands as therapeutics and diagnostics thereby dramatically affecting the delivery system in health care. MN arrays are made of several micron-sized needles with a height usually between 25 and 2000 µm, of various forms and compositions such as silicon, metal, and biodegradable polymers. With the help of current developments in additive manufacturing procedures, such as two-photon polymerization fabrication and 3D printing, microneedle designs with feature sizes ranging from sub-micron to millimeters may be produced. The technology has the potential to provide feasible methods to deliver medications via impermeable barriers in addition to being minimally invasive and patient-compliant and having the capacity to cross many biological barriers. The method has been effective in removing the barriers to direct drug delivery to the targeted areas, increasing the efficiency and lowering the dose needed. A considerable quantity of MN-mediated vaccine candidates have reportedly demonstrated promising outcomes in preclinical and clinical studies. Vaccine delivery is used as an advanced technique. They are a better option since they may be self-administered, painless, and provide improved immunogenicity. In addition to providing an overview of microneedle drug delivery system, selection of materials, designs, manufacturing techniques, and possible safety implications, and applications, the current paper also sheds light on probable future developments in the area of microneedle innovation.

Performance and ecological impacts of benthic barriers for the control of an invasive plant in a small urban lake

Yellow Floating Heart (YFH), Nymphoides peltata, is a rooted aquatic plant that is not native to North America, and can quickly establish nuisance populations in shallow lakes, rivers, and wetlands. There are few documented methods for effectively eradiating or controlling YFH. Little Albro Lake is a small (3 ha), shallow (<5 m deep) meso-eutrophic lake in Dartmouth, Nova Scotia, Canada that experiences an annual YFH infestation covering >50% of the lake during the growing season. A pilot study was conducted during the 2021 growing season to: (i) assess the feasibility of using benthic barriers to control YFH growth, and (ii) investigate the potential impacts of benthic barriers on ecosystem components. Two commercially available benthic barriers (Aquascreen, a permeable barrier, and Lake Bottom Blanket, an impermeable barrier) were tested in shallow (1 m water depth) and deep (3 m water depth) areas of the lake. A total of 18 test plots (6 permeable, 6 impermeable, 6 control), each measuring 3 m × 3 m, were established in early May 2021, and monitored throughout the growing season (May–September). Both types of barriers were effective in reducing YFH growth, with barriered plots possessing significantly less YFH coverage than control plots. Inspection of the permeable barriers after their removal from the lake, however, revealed that YFH had been able to grow through this type of barrier material. Several maintenance issues were also noted with both barriers including: (i) gas build-up under the barriers, which caused billowing, and (ii) an accumulation of sediment on top of the barriers and growth of YFH through these sediment layers. Both issues would need to be managed during a full-scale benthic barrier application program. An environmental effects monitoring program was also undertaken to understand the lake ecosystem and impacts of the barriers on the chemical and biological properties of the lakebed. The barriers had measurable impacts on the lakebed and generated lower oxidation reduction potential (ORP) in sediments, as compared to control plots with no barriers. Reduced ORP in lake sediments could facilitate the mobilization of redox-sensitive metals, such as arsenic and iron. There were only minor differences in benthic macroinvertebrate populations when comparing barriered and control plots. The bacterial alpha-diversity of the lakebed sediment was shown to differ by depth, with the shallow zone having higher observed ASVs and diversity levels. However, within the two depth zones, the barriers did not appear to have a large impact on bacterial community composition and potential functionality. In conclusion, benthic barriers can be used to prevent YFH growth, however barrier installations require maintenance and may reduce sediment ORP, potentially leading to release of redox-sensitive metals and nutrients.

Structural properties of the Southern San Andreas fault zone in northern Coachella Valley from magnetotelluric imaging

SUMMARYThe Southern San Andreas fault (SSAF) poses one of the largest seismic risks in California. Yet, there is much ambiguity regarding its deeper structural properties around Coachella Valley, in large part due to the relative paucity of everyday seismicity. Here, we image a multistranded section of the SSAF using a non-seismic method, namely magnetotelluric (MT) soundings, to help inform depth-dependent fault zone geometry, fluid content and porosity. The acquired MT data and resultant inversion models highlight a conductive column encompassing the SSAF zone that includes a 2–3 km wide vertical to steeply northeast dipping conductor down to ∼4 km depth (maximum of ∼1 Ω·m at 2 km depth) and another prominent conductor in the ductile crust (∼1 Ω·m at 12 km depth and slightly southwest of the surface SSAF). We estimate porosities of 18–44 per cent for the conductive uppermost 500 m, a 10–15 per cent porosity at 2 km depth and that small amounts (0.1–3 per cent) of interconnected hypersaline fluids produce the deeper conductor. Located northeast of this conductive region is mostly resistive crust indicating dry crystalline rock that extends down to ∼20 km in places. Most of the local seismicity is associated with this resistive region. Located farther northeast still is a conductive region at &amp;gt;13 km depth and separate from the one to the southwest. The imaged anomalies permit two interpretations. The SSAF zone is vertical to steeply northeast dipping in the upper crust and (1) is near vertical at greater depth creating mostly an impermeable barrier for northeast fluid migration or (2) continues to dip northeast but is relatively dry and resistive up to ∼13 km depth where it manifests as a secondary deep ductile crustal conductor. Taken together with existing knowledge, the first interpretation is more likely but more MT investigations are required.

3D geological modeling for Yamama reservoir in Al-Nasiriyah oil field Southern Iraq

The geological modeling of an oil-bearing reservoir, which specifies the lithology and analyzes the petrophysical parameters of complex reservoir, its being created using Petrel software to construct reservoir models that describe and estimate porosity and water saturation distributions. 3D modeling of carbonate reservoirs has proven to be a highly effective technique for evaluate the economic benefit of the reservoir by estimating the formation petrophysical properties and calculating the oil reserves. The study aims constructed on evaluated Yamama formation in Four drilling wells (Nasiriyah-1, Nasiriyah-3, Nasiriyah-4, and Nasiriyah-5) entering the Yamama Formation of the Al-Nasiriyah field. In Al-Nasiriyah Oil field, and within the Lower Cretaceous Stratigraphic Column in the south of Iraq, the Yamama Formation is one of the most important reservoirs that deposited into shallow marine habitats throughout the (Valanginian- Early Hauterivian) period, that made up of reservoir and impermeable barrier units in the Al-Nasiriyah field, Yamama Reservoir units are divided into three reservoir units (YA, YB, and YC), with the YB reservoir unit subdivided into (YB1, YB2, and YB3) subunits. The main reservoir units are separated by four sharp impermeable barriers represented by (B1, B2, B3, and B4).

Melt-Quenched Glass Films of Coordination Polymers as Impermeable Barrier Layers and Protective Anticorrosion Coatings

Melt-Quenched Glass Films of Coordination Polymers as Impermeable Barrier Layers and Protective Anticorrosion Coatings

Effect of salt permeants on the consolidation and hydraulic behaviour of fibre treated black cotton soil for landfill application

Clay liner functions as an impermeable barrier between leachate and groundwater in landfills. In this work, naturally available black cotton (BC) soil is adopted as a liner material due to its high swelling and low hydraulic conductivity, which helps to eliminate the risk of groundwater pollution by preventing pollutant mobility. The liner's potential is threatened by two issues: shrinkage cracks and chemical attacks. BC soil induces desiccation cracks and high compressibility due to its high shrinkage potential upon drying, which severely impacts its hydraulic conductivity behaviour. In recent years, fibres have been used as reinforcing materials to control compressibility and shrinkage cracks of the liner. In this investigation, waste tire fibres, which were used as a reinforcing material, mixed with BC soil in the proportion of 5, 10 and 15% by their dry weight. Since the essential parameters of liner would change due to the interaction of chemicals in leachate, hence, this study examined the consolidation and hydraulic properties of fibre mixed BC soil in the presence of two inorganic salt permeants (NaCl and CaCl2) of two concentrations (0.1 and 1N) to mimic the leachate effect. The results revealed that when salt solutions were utilised as saturating pore liquids, the time to achieve the 90% of consolidation (t90) of fibre-treated BC soil was decreased, thereby increasing the coefficient of consolidation (cv). These changes were more significant at higher concentrations of pore liquids. The t90 value for 15% fibre-treated soil with DI water is 27.0 min, and it decreased drastically to 0.8 min (97.0% reduction) for 1N NaCl solution and 0.6 min (97.8% reduction) for 1N CaCl2 solution at the higher consolidation pressure of 784.5 kPa. Compression index (Cc) and void ratio (e) were reduced with the salt permeants irrespective of the fibre content. Finally, it was shown that salts substantially impact the hydraulic conductivity values of fibre-treated soil and that up to 10% fibre content is appropriate for landfill liner application.

Patterns of genetic diversity of brown trout in a northern Spanish catchment linked to structural connectivity

The alteration of structural connectivity in fluvial networks is important for the genetic dynamics of aquatic species. Exploring the effects of network fragmentation through genetic analysis is crucial to assess the conservation status of riverine species. In this study, we investigated the genetic consequences of the altered connectivity of brown trout in the Deva–Cares catchment (northern Spain). We investigated (1) genetic diversity, (2) genetic differentiation and genetic structure, (3) migration rates and effective population size and (4) genetic differentiation and riverscape characteristics. Analysis of the genetic variation among 197 individuals from the 13 study sites revealed a high degree of genetic differentiation (FST = 0.181). Below-barrier study sites had higher genetic diversity and lower FST values, while headwater and above-barrier study sites had lower genetic diversity and higher FST values. Most of the genetic groups identified were separated by one or more impermeable barriers. We reported an abrupt decrease in genetic diversity and effective population size in upper course tributaries and isolated reaches. Likewise, a downstream-biased gene flow was found, and it was most likely related to the fragmentation caused by barriers, since the results from migration indicated that gene flow between groups without impermeable barriers was higher bidirectionally. Isolation by impermeable barriers played a more important role than hydrological distance in determining the genetic structure. Most of the genetic groups showed small effective population sizes. Genetic analysis at the river network scale provides evidence for the role of barriers in determining genetic diversity patterns, highlighting the importance of maintaining and restoring river longitudinal connectivity.