Dual Barrier Research Articles

Sequential Nano-Penetrators of Capillarized Liver Sinusoids and Extracellular Matrix Barriers for Liver Fibrosis Therapy.

During liver fibrogenesis, liver sinusoidal capillarization and extracellular matrix (ECM) deposition construct dual pathological barriers to drug delivery. Upon capillarization, the vanished fenestrae in liver sinusoidal endothelial cells (LSECs) significantly hinder substance exchange between blood and liver cells, while excessive ECM further hinders the delivery of nanocarriers to activated hepatic stellate cells (HSCs). Herein, an efficient nanodrug delivery system was constructed to sequentially break through the capillarized LSEC barrier and the deposited ECM barrier. For the first barrier, LSEC-targeting and fenestrae-repairing nanoparticles (named HA-NPs/SMV) were designed on the basis of the modification with hyaluronic acid and the loading of simvastatin (SMV). For the second barrier, collagenase I and vitamin A codecorated nanoparticles with collagen-ablating and HSC-targeting functions (named CV-NPs/siCol1α1) were prepared to deliver siCol1α1 with the goal of inhibiting collagen generation and HSC activation. Our in vivo results showed that upon encountering the capillarized LSEC barrier, HA-NPs/SMV rapidly released SMV and exerted a fenestrae-repairing function, which allowed more CV-NPs/siCol1α1 to enter the space of Disse to degrade deposited collagen and finally to achieve higher accumulation in activated HSCs. Scanning electronic microscopy images showed the recovery of liver sinusoids, and analysis of liver tissue sections demonstrated that HA-NPs/SMV and CV-NPs/siCol1α1 had a synergetic effect. Our pathological barrier-normalization strategy provides an antifibrotic therapeutic regimen.

Dual Poroviscoelastic Wave Barriers for Compliant Floating Platforms

Dual Poroviscoelastic Wave Barriers for Compliant Floating Platforms

Shielding Surfaces from Viruses and Bacteria with a Multiscale Coating.

The spread of viral and bacterial pathogens mediated by contact with surfaces is a leading cause of infection worldwide. COVID‐19 and the continuous rise of deaths associated with antibiotic‐resistant bacteria highlight the need to impede surface‐mediated transmission. A sprayable coating with an intrinsic ability to resist the uptake of bacteria and viruses from surfaces and droplets, such as those generated by sneezing or coughing, is reported. The coating also provides an effective microbicidal functionality against bacteria, providing a dual barrier against pathogen uptake and transmission. This antimicrobial functionality is fully preserved following scratching and other induced damage to its surface or 9 days of submersion in a highly concentrated suspension of bacteria. The coatings also register an 11‐fold decrease in viral contamination compared to the noncoated surfaces.

Anti-corrosion epoxy/modified graphene oxide/glass fiber composite coating with dual physical barrier network

Polymer matrix composite with a physical barrier network can efficiently inhibit corrosion on carbon steel. In this paper, 3-(2-Aminoethylamino) propyldimethoxymethylsilane modified graphene oxide (A-GO) and glass fiber (GF) were incorporated into Epoxy (EP) matrix, and EP/GF/A-GO composite coating with dual physical barrier network was prepared. The electrochemical impedance spectroscopy (EIS) showed that the impedance modulus of EP/GF/A-GO composite coating was highest among the different coatings, indicting EP/GF/A-GO composite coating with dual physical barrier network could significantly enhance the corrosion protection properties. Even after 45 days of immersion, the value of impedance modulus of the EP/GF/A-GO composite coating was above 3.9 × 107 Ω cm2. Moreover, the anti-corrosion protection mechanism of EP/GF/A-GO composite coating was investigated. EP/GF/A-GO composite coating has excellent anti-corrosion protection performance.

Boosting college prospects among low-income students: Using self-affirmation to trigger motivation and a behavioral ladder to channel it.

Access to college for students from low-income families is disproportionately low because of many factors. A targeted intervention that addresses social psychological factors is introduced in the present paper. It is hypothesized that the steps needed to go to college-applying for college and applying for financial aid-can be blocked by both psychological and behavioral friction. The psychological friction arises from the threats to self-integrity that low-income students experience when considering attending college. Behavioral friction takes the form of institutional and bureaucratic barriers that students must overcome to apply to college and for financial aid. Two interventions are tested separately and in combination to address these dual barriers. A self-affirmation intervention in which students wrote about important values aimed to alleviate threats to self-integrity; and a behavioral ladder intervention that provided a series of timely reminders or "nudges" and accompanying strategies to students through a mobile application (app) at key decision points along the college admissions process addressed behavioral friction. Students who received the behavioral ladder made further progress along the college admission pipeline based on official records, an effect that was apparent only in the affirmation condition. These results illustrate the efficacy of combining "wise" interventions to address discrete barriers, the importance of tailoring and timing intervention content to key points of friction, and the potential of mobile technology to facilitate both objectives. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Fully armed photodynamic therapy with spear and shear for topical deep hypertrophic scar treatment

5-aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) has emerged as a promising therapy for hypertrophic scar (HS). However, the poor permeability of ALA across biological barriers and pro-survival autophagy of fibroblasts largely restricted the efficacy of PDT. Herein, PDT was well equipped with spear and shear to overcome the therapeutic resistance. Specifically, hyaluronidase (HAase) based dissolving microneedles (MN)with improved stiffness and permeability were developed as a spear to deliver ALA into deep lesions by combating the dual barriers of stratum corneum and dense extracellular matrix (ECM). Besides, metformin (Met) MN was applied as a shear to intervene the respiration and autophagic process for amplified PDT. HAase significantly enhanced the in vitro and in vivo transdermal delivery efficiency of ALA, while the combination of HAase and Met successfully amplified the anti-scarring efficacy of PDT by elevating cytotoxicity, promoting permeation, activating signal pathways, and interdicting the autophagy process simultaneously. The pharmacodynamics study revealed that the combination therapy achieved the lowest scar elevation index (SEI), downregulated expression of collagen I and TGF-β1, and decreased LC3 II/I ratio, showing excellent therapeutic efficacy. Therefore, such a fully armed PDT integrating double-prolonged attack on the physiological and pathological barriers offers a promising topical treatment for deep HS.

Performance of Dual Viscoelastic Wave Barrier System with Unequal Draft

This work investigated the interaction of surface waves with a dual-barrier system comprising two vertical viscoelastic thin sheets with variable spacing in finite water depth without preassumption of its dynamic behavior. The two sheets were assumed to be made of the same material and under different tensions, and both penetrated into the water depth partially with unequal drafts. The viscoelastic behavior of the sheet material, which accounts for its elastic deformation and internal energy dissipation, is represented by the Voigt model. Using the eigenfunction expansion and least square determination, analytical solutions were obtained for the dual-barrier system, including the asymptotic case of a single sheet when the second sheet draft approaches zero. Subsequently, the effects of hydroelastic regimes and viscoelasticity were examined. With the single-sheet system, the wave transmission decreases as the tensioned sheet shifts from platelike to membranelike, and its material has higher internal energy dissipation (i.e., viscosity). When the size of the bottom opening increases to a gap ratio larger than ∼0.6, however, the wave transmission becomes dominated by the diffraction through the gap, and the influence of sheet material characteristics is no longer significant. With the double-sheet system, the results show that the performance of the wave barrier improves significantly by the presence of the second sheet, even with a small draft. Complex resonating patterns can be observed with increase in sheet spacing for the dual-barrier system, which reduces the wave transmission. The presence of viscosity of the double-sheet system dampens the resonance, but also reduces the wave transmission by itself through the viscous dissipation of the incident wave energy.

Effects of basal clearance on the impact dynamics of dry granular flow against dual rigid barriers

A basal clearance is usually designed beneath barriers to enable sufficient discharge to minimise the maintenance work over service life. Current design guidelines for multiple barriers usually neglect the influence of basal clearance, resulting in either an overconservative or a nonconservative design impact force acting on the subsequent barriers. In this study, physical model tests were carried out to investigate the effects of basal clearance height (Hc) beneath first barrier on the interaction between dry granular flow and dual rigid barriers. A new approach based on the hydrodynamic equation is proposed to estimate the impact force on the second barrier exerted by the basal discharge and overflow from the first barrier. The basal discharge can attenuate the impact force exerted on the second barrier by dissipating the kinetic energy of landing flow and apportioning the load contributions from basal discharge and overflow. For the first barrier with a barrier height HB1 that was twice the flow depth h0, the impact force on the second barrier was governed by overflow when Hc/h0 ≤ 0.6 and was dominated by basal discharge when Hc/h0 ≥ 0.8. These two criteria provide a basis for optimising the impact forces for multiple-barrier systems with basal clearances.

Epoxy-ester coating reinforced with cerium (III)-tannic acid-based hybrid pigment for effective mild-steel substrate corrosion protection

Epoxy ester coating with dual active inhibition and passive barrier anti-corrosion properties was constructed using a novel hybrid pigment based on the cerium nitrate and tannic acid (Ce-TAA). At first, the inorganic-organic pigment was synthesized and then characterized by FTIR, TGA, and Raman methods. Electrochemical measurements evidenced an inhibition degree of 81% for the metal sample exposed to the saline solution containing the Ce-TAA pigment extract. The polarization test showed significant corrosion current density reduction via a mixed corrosion retardation mechanism. According to the UV–visible and ICP analyses outcomes, the solubility of the hydrophilic tannic acid and cerium nitrate decreased in the cerium-tannate complex. EIS results evidenced that the |Z|at10 mHz and Rct values of the Ce-TAA containing coating with defect increased over time. Besides, up to 21 days of immersion, the Ө values near to −90° and the |Z|10 mHz > 107 Ω·cm2 were recorded for the intact coating containing Ce-TAA pigment. Via FE-SEM/EDS analyses the released inhibitive species were detected on the scratched areas of the coating.

The effects of upstream flexible barrier on the debris flow entrainment and impact dynamics on a terminal barrier

The destructive nature of debris flows is mainly caused by flow bulking from entrainment of an erodible channel bed. To arrest these flows, multiple flexible barriers are commonly installed along the predicted flow path. Despite the importance of an erodible bed, its effects are generally ignored when designing barriers. In this study, three unique experiments were carried out in a 28 m long flume to investigate the impact of a debris flow on both single and dual flexible barriers installed in a channel with a 6 m long erodible soil bed. Initial debris volumes of 2.5 and 6 m3 were modelled. For the test setting adopted, a small upstream flexible barrier before the erodible bed separates the flow into several surges via overflow. The smaller surges reduce bed entrainment by 70% and impact force on the terminal barrier by 94% compared to the case without an upstream flexible barrier. However, debris overflowing the deformed flexible upstream barrier induces a centrifugal force that results in a dynamic pressure coefficient that is up to 2.2 times higher than those recommended in guidelines. This suggests that although compact upstream flexible barriers can be effective for controlling bed entrainment, they should be carefully designed to withstand higher impact forces.

Membrane Distillation Provides a Dual Barrier for Coronavirus and Bacteriophage Removal.

The persistence of pathogenic microorganisms in treated wastewater effluent makes disinfection crucial to achieve wastewater reuse. Membrane processes such as ultrafiltration and reverse osmosis (RO) have shown promising results for virus and other contaminant removal from treated wastewater effluents for reuse application. However, RO produces a concentrate stream which contains high concentrations of pathogens and contaminants that often requires treatment and volume reduction before disposal. Membrane distillation (MD) is a treatment process that can reduce RO concentrate volume while augmenting the potable water supply. MD is also a dual barrier approach for virus removal as it operates at a high temperature and permeates only the vapor phase through the membrane interface. The effects of temperature on viable virus concentration and membrane rejection of viruses in MD are investigated in this study using two nonenveloped phages frequently used as enteric virus surrogates (MS2 and PhiX174) and an enveloped pathogenic virus (HCoV-229E). At typical MD operating temperatures (greater than 65 °C), viable concentrations of all three viruses were reduced by thermal inactivation by more than 6-log10 for MS2 and PhiX174 and more than 3-log10 for HCoV-229E. Also, membrane rejection was greater than 6-log10 for MS2 and PhiX174 and greater than 2.5-log10 for HCoV-229E.

Constructing robust chain entanglement network, well-defined nanosized crystals and highly aligned graphene oxide nanosheets: Towards strong, ductile and high barrier Poly(lactic acid) nanocomposite films for green packaging

It is a great challenge to develop a feasible strategy for reconciling barrier performance and mechanical ductility of environmentally friendly poly(lactic acid) (PLA) in the application of packaging industry. In the current study, the combination of manipulating the amorphous chain entanglement network of PLA and constructing “dual barrier walls” of highly aligned GONSs and well-defined PLA crystals simultaneously enhanced barrier properties and ductility of PLA nanocomposite films via “biaxial stretching-constrained annealing” method. The intense extensional field during biaxial stretching induced highly aligned GONSs as the first barrier wall and regulated the amorphous chain entanglement network. Constrained annealing promoted the growth and perfection of PLA crystals as the second effective barrier wall and strengthened amorphous chain entanglement network to some extent. More interestingly, GONSs were first verified as contributors to stabilize the enhanced amorphous chain entanglement network of PLA and benefited for the mechanical ductility of PLA nanocomposite films. As a result, this synergetic structure manifested excellent comprehensive ability in ameliorating the intrinsic drawbacks of brittle and poor barrier PLA films, exhibiting low oxygen permeability coefficient of 0.712 × 10−14 cm3 cm cm−2 s−1 Pa−1, excellent ductility with elongation at break of 147.8%, high yield strength of 83.1 MPa and good dimensional stability with deformation ratio of as low as 3%. The as-prepared PLA nanocomposite films with excellent comprehensive properties hold great potential prospects in the application of packaging industry. The methodology proposed here opens up a new avenue to fabricate environmentally friendly PLA films for promoting the sustainable development of packaging industry.

Performance evaluation of liner dual barrier system in CO2-rich geothermal wells

Geothermal well construction typically consists of a slotted production liner to support the wellbore and provide a conduit for produced reservoir fluids. To maintain the integrity of the well, the production liner is designed with a dual barrier system - a seal assembly at the top of the liner and a cement sheath between the formation and the liner. The integrity of barrier elements can compromise due to the degradation caused by acidic gases such as H2S and CO2 that usually exist in geothermal reservoirs. In this paper, experimental and numerical studies were conducted to evaluate dual barrier system's performance and identify its failure modes at various downhole conditions.In this study, an experimental setup was designed to replicate the production liner dual barrier system consisting of a cement sheath and elastomer O-rings. The hydraulic and mechanical integrity of the seal assembly and the cement sheath barriers were investigated by conducting pressure tests. EPDM elastomer and neat class H cement were used as the barrier materials. The performance of elastomer was investigated after aging in an autoclave at 1000 psi and 180°F under CO2 exposure. The performance of the cement was evaluated at different wait on cement (WOC) intervals. Verified finite element models (FEM) were developed to simulate the response of barrier elements under different conditions.Results indicated that exposure to CO2 compromised the hydraulic integrity of the seal element. The structural integrity of the elastomer was also jeopardized after CO2 aging, as evident by the blisters and cracks visually detected on elastomers’ surfaces. Verification by sealability test indicates that FEA modeling can be a reliable tool for estimating seal performance if elastomer material properties are known for the design conditions. Simulation results demonstrate that CO2 exposure can reduce the sealability of EPDM elastomer (measured in terms of contact stress) by up to 37%.For cement, the experimental results demonstrated insufficient interfacial bonding between cement and the inner pipe, as evidenced by the leak pathways observed during the hydraulic integrity tests. WOC time improves the hydraulic integrity of cement barrier element. Mechanical properties of cement cured at the elevated temperatures of up to 350°F were used in the FEA model to investigate the impact of temperature and wellbore pressure load on cement integrity. The results revealed that tensile hoop stress induced by the wellbore pressure loads is a likely failure mechanism that compromises the mechanical integrity of cement in geothermal wells. Results indicate that neat Class H cement may not serve as a reliable barrier in case of a defective seal assembly of a liner hanger. Overall, this paper identifies some of the barrier elements’ major limitations and provides recommendations for designing barriers and improving well integrity.

Virus-Mimicking Mesoporous Silica Nanoparticles with an Electrically Neutral and Hydrophilic Surface to Improve the Oral Absorption of Insulin by Breaking Through Dual Barriers of the Mucus Layer and the Intestinal Epithelium.

Protein and peptide drugs orally suffer from extremely low bioavailability principally for the complicated gastrointestinal environment along with the difficulty of passing through the mucus layer and the underlying epithelium. In our work, we fabricated mesoporous silica nanoparticles with modification groups (MSN-NH2@COOH/CPP5) that effectively penetrated the mucus layer and passed through the intestinal epithelium by mimicking the virus surface. Naked nanoparticles were prepared with inner pores of 6 nm diameter to allow efficient insulin loading and coated with the cationic cell-penetrating KLPVM peptide and the anionic glutaric anhydride to yield hydrophilic MSN-NH2@COOH/CPP5 with a ζ-potential of -0.49 mV. The apparent permeability coefficient of virus-mimicking nanoparticles was 14.61 × 10-5 cm/s. The virus-mimicking nanoparticles showed dramatically lower binding to mucin and faster penetration of the mucus layer than positively charged nanoparticles (MSN@NH2) with a ζ-potential of +35.00 mV. The KLPVM peptide enhanced the uptake of MSN-NH2@COOH/CPP5 by coculturing Caco-2 and E12 cells as an intestinal epithelium model. MSN-NH2@COOH/CPP5 enhanced apical-to-basal transcytosis for being internalized primarily through caveolae-mediated endocytosis. Indeed, for MSN-NH2@COOH/CPP5, the transepithelial transport of the Caco-2 cell monolayer was 2.4-fold higher than MSN@NH2 and 2.0-fold higher than MSN-NH2@COOH. In vitro, loading insulin into nanoparticles maintained the bioactivity of the protein under simulated intestinal conditions. Insulin loaded into MSN-NH2@COOH/CPP5 reduced the diabetic rats' blood glucose level by nearly 50%. The bioavailability of insulin encapsulated in the MSN-NH2@COOH/CPP5 nanoparticles was 2.1-fold more than insulin when administered directly into the jejunum. Nanoparticles with modifications indicated no significant toxicity in in vitro or in vivo preliminary studies. The obstacles of the mucus layer and intestinal epithelium may be effectively conquered by these virus-mimicking nanoparticles for oral delivery of protein and peptide drugs.

New impact equation using barrier Froude number for the design of dual rigid barriers against debris flows

In the design of multiple rigid barriers, the height of the first barrier governs the impact dynamics of debris flow on the next barrier in a channel. However, current design approaches neglect the height of the first barrier, and no specific guideline is given on the design of the impact load on the second barrier. In this study, a new impact equation that explicitly considers the effects of the height of the first barrier on the impact dynamics is proposed. This is achieved by adopting the barrier Froude number Frb, which is the ratio of inertia to barrier potential. Thereby, the new impact equation accounts for the static load as a function of the first barrier height. The equation is evaluated using physical experiments carried out in a 5-m-long flume. The experiments modelled dry sand and water flows impacting dual rigid barriers. These two idealised flow types represent extreme cases of frictional and viscous flows, which exhibit entirely different impact mechanisms. A comparison of the experimental results from this study shows that the proposed impact model using the barrier Froude number provides a reasonably conservative estimate for the normalised impact force on the first rigid barrier with overflow. Furthermore, a bilinear design envelop for the impact force exerted on the second barrier is proposed based on the barrier Froude number of the first barrier.

An algorithm for nonsymmetric conic optimization inspired by MOSEK

We analyse the scaling matrix, search direction, and neighbourhood used in MOSEK's algorithm for nonsymmetric conic optimization [J. Dahl and E.D. Andersen, A primal-dual interior-point algorithm for nonsymmetric exponential-cone optimization, preprint (2019)]. It is proven that these can be used to compute a near-optimal solution to the homogeneous self-dual model in polynomial time. This provides a theoretical foundation for MOSEK's nonsymmetric conic algorithm. The main steps in the analysis are sandwiching MOSEK's scaling matrix between the primal and dual barrier's Hessians, and using this information to carefully check all the neighbourhood conditions after a small, improving step is taken.

In Situ Formed Metal Oxide/Metal Interface Enhanced C–C Coupling in CO2 Reduction into CH3COOH over Hexagonal Closed-Packed Cobalt

Conversion of CO2 into value-added chemicals and fuels is one promising method for mitigating global warming and fossil fuel depletion. However, hindered by the dual barriers of CO2 activation and selective catalytic C–C coupling, hydrogenation of CO2 into multicarbon products, especially for organic acids, still remains a great challenge. In this work, an acetate yield of 9.5% from direct CO2 reduction was obtained via a specific hexagonal closed-packed cobalt (HCP-Co) catalyst under hydrothermal conditions. Results showed that the in situ formed CoO/Co interface was the key for the CO2 activation and subsequent C–C coupling. The unique properties of hydrothermal reactions were found to modulate the proportion of metal oxide/metal on the catalyst surface, which then gave a stable formation of CoO/Co interface. A plausible reaction pathway is also proposed based on the time-dependent experiments and DFT calculation, in which *CH2 and HCOO as the intermediates were combined to form CH3COO– through the carbene reaction. This study provides a robust approach for C–C coupling in CO2 hydrogenation without noble metal catalysts, which is essential for the practical application.

Dual Metal Gate Dielectric Engineered Dopant Segregated Schottky Barrier MOSFET With Reduction in Ambipolar Current

In this paper, to solve the problem of higher ambipolar leakage current (Iambipolar) of Dielectric Engineered (DE) Dopant Segregated (DG) Schottky Barrier (SB) MOSFET (DE DS SBMOS), we have incorporated dual metal gate (DMG) in place of single metal gate for the DE DS SBMOS. The proposed device is named as DMG DE DS SBMOS. In a proposed device, the gate is consisting of dual metal having different work functions. Therefore, the gate is divided in two parts named as auxiliary gate (AG) and tunneling gate (TG). AG and TG employed near the source and drain (S/D) ends, respectively. AG is mainly used to control the on-state performance and TG for the off-state performance by modulating the SB height and width at S/D end, respectively. Simulation results show that Iambipolar of the device has been successfully suppressed by choosing appropriate work functions for AG and TG without affecting the on-state current (Ion) of the device. The proposed device combines the advantage of dual metal gate and dielectric engineering to achieve improvement in the overall performance of the device. The proposed device exhibits high Ion, low Iambipolar and low subthreshold swing (SS). The simulations study verifies the use of the proposed device for low power applications.

Dual layer barrier functions based adaptive higher order sliding mode control

AbstractThis article presents an adaptive discontinuous higher order sliding mode control (HOSMC) strategy for a disturbed chain of integrators of order n. This strategy employs a barrier function‐based dual layer adaptation and it ensures the convergence of the sliding variable and its (n − 1) first derivatives to zero without requiring any information on the bounds of the disturbances or their derivatives. It consists in applying a barrier function‐based adaptive super‐twisting methodology compensating Lipschitz disturbances with some error, and a growing gain‐based adaptive HOSMC which just needs to counteract this error. Real‐time simulation platform is used to test the efficacy of the proposed strategy to control a linear induction motor considering dynamic end effects.

Effects of wait on cement, setting depth, pipe material, and pressure on performance of liner cement

An intact cement sheath between a liner and its host casing is critical for maintaining well integrity. The liner-casing overlap incorporates a cement sheath and a seal assembly that collectively establish a dual barrier system. This type of barrier provides a unique set of hydraulic and mechanical properties that are necessary to isolate fluids and prevent undesired communication between formations, wellbore, and environment. The hydraulic and mechanical integrity of the cement sheath can be compromised as a result of stresses induced by various drilling, completion, intervention, stimulation, production, and injection operations.The assessment of cement sheath integrity in the liner barrier system has been a major concern for both the industry as well as the regulators. The objective of this paper is to study the mechanical integrity and the risk of failure at the casing-cement and cement-liner interfaces. The evaluation was performed for various downhole pressure conditions, cement and pipe properties, wait-on-cement (WOC) intervals, and liner setting depths. Analytically and experimentally validated finite element modelling (FEM) approach was employed in this work. The simulation results indicate that tensile hoop stress generated by pressure loads, is one of the most dominant factors that compromises the cement mechanical integrity. This observation was supported by the radial cracks observed during the experimental pressure tests. This work advances design and performance evaluation guidelines for liner cements. Results presented will assist engineers in predicting cement failure modes and identifying operation limits to consider during a well's life cycle.