Barrier Type Research Articles

The Drosophila Blood-Brain Barrier Adapts to Cell Growth by Unfolding of Pre-existing Septate Junctions

The blood-brain barrier is crucial for nervous system function. It is established early during development and stays intact during growth of the brain. In invertebrates, septate junctions are the occluding junctions of this barrier. Here, we used Drosophila to address how septate junctions grow during larval stages when brain size increases dramatically. We show that septate junctions are preassembled as long, highly folded strands during embryonic stages, connecting cell vertices. During subsequent cell growth, these corrugated strands are stretched out and stay intact during larval life with very little protein turnover. The G-protein coupled receptor Moody orchestrates the continuous organization of junctional strands in a process requiring F-actin. Consequently, in moody mutants, septate junction strands cannot properly stretch out during cell growth. To compensate for the loss of blood-brain barrier function, moody mutants form interdigitating cell-cell protrusions, resembling the evolutionary ancient barrier type found in primitive vertebrates or invertebrates such as cuttlefish.

Analysis of eosinophilic esophagitis in children with repaired congenital esophageal atresia

A high prevalence of eosinophilic esophagitis (EoE) has been preliminarily reported in patients after repair of esophageal atresia (EA), but the basis of this association is unknown. We aimed to (1) characterize the EoE transcriptome in patients with EA, (2) compare the EoE transcriptome in patients with EoE and EA with that in patients with EoE alone, and (3) identify transcripts that could predispose patients with EA to EoE. This single-center, population-based, retrospective study identified 4 EoE study cohorts: healthy control subjects, patients with EA and EoE (EA+EoE+), patients with EA without EoE (EA+EoE-), and patients with EoE without EA (EA-EoE+). Molecular signatures were assessed by using the EoE diagnostic panel, a 94-gene expression quantitative PCR array. In a cohort of 110 pediatric patients with surgically repaired EA, 20 (18%) patients were given a diagnosis of EoE, representing a 364-fold enrichment of EoE in patients with EA compared with the general pediatric population. EoE diagnostic panel analyses revealed a major overlap between the EA+EoE+ and EA-EoE+cohorts. Aproportion (approximately 25%) of EoE signature genes were dysregulated in patients with EA+EoE- compared with healthy control subjects, including those involved in epithelial barrier function and type 2-associated inflammatory responses. Patients with EA+EoE+exhibit a more severe EoE clinical phenotype than those with EA-EoE+ in terms of dysphagia and dilation need. Patients with EA have increased risk of EoE. Patients with EoE with EA have a similar molecular profile compared with that of patients with EoE without EA. Dysregulated baseline epithelial barrier and type 2-associated genes in EA monomorbidity might explain the higher EoE prevalence in patients with EA.

Adaptive Fuzzy Output Feedback Control for a Class of Nonlinear Systems With Full State Constraints

In the paper, the adaptive observer and controller designs based fuzzy approximation are studied for a class of uncertain nonlinear systems in strict feedback. The main properties of the considered systems are that all the state variables are not available for measurement and at the same time, they are required to limit in each constraint set. Due to the properties of systems, it will be a difficult task for designing the controller and the stability analysis. Based on the structure of the considered systems, a fuzzy state observer is framed to estimate the unmeasured states. To ensure that all the states do not violate their constraint bounds, the Barrier type of functions will be employed in the controller and the adaptation laws. In the stability analysis, the effect caused by the constraints for all the states can be overcome by using the Barrier Lyapunov functions. Based on the proposed control approach, it is proved that the system output is driven to track the reference signal to a bounded compact set, all the signals in the closed-loop system are guaranteed to be bounded, and all the states do not transgress their constrained sets. The effectiveness of the proposed control approach can be verified by setting a simulation example.

Dividends: From refracting to ratcheting

In this paper we consider an alternative dividend payment strategy in risk theory, where the dividend rate can never decrease. This addresses a concern that has often been raised in connection with the practical relevance of optimal classical dividend payment strategies of barrier and threshold type. We study the case where once during the lifetime of the risk process the dividend rate can be increased and derive corresponding formulas for the resulting expected discounted dividend payments until ruin. We first consider a general spectrally-negative Lévy risk model, and then refine the analysis for a diffusion approximation and a compound Poisson risk model. It is shown that for the diffusion approximation the optimal barrier for the ratcheting strategy is characterized by an unexpected relation to the case of refracted dividend payments. Finally, numerical illustrations for the diffusion case indicate that with such a simple ratcheting dividend strategy the expected value of discounted dividends can already get quite close to the respective value of the refracted dividend strategy, the latter being known to be optimal among all admissible dividend strategies.

Frequency Response of Barrier Type 2.6 µm In0.83 Ga0.17 As/In0.83 Al0.17 As Photodetectors on InP

Frequency Response of Barrier Type 2.6 µm In_0.83 Ga_0.17 As/In_0.83 Al_0.17 As Photodetectors on InP

Role of drainage and barriers in the genetic structuring of a tessellated darter population

While population genetic structuring is easily identified, the causes of the structure can be difficult to determine. Habitat fragmentation in aquatic systems has often been identified as a major source of increased population structure and decreased genetic diversity in fish, including benthic resident species such as darters. However, these findings are often not replicated across natural and manmade barriers and come from endangered or threatened populations where the genetic structure is likely already compromised due to small population size. To evaluate the factors involved in structuring a healthy darter population, we genotyped 506 tessellated darters from 18 sites in three different river drainages and one large lake. Sites were all in the same watershed but separated from one another by one or more of three different types of barriers: dams, natural fall lines and causeways. We found that while diversity and allele frequency varied largely by drainage, within drainage variation was minimal even across multiple barriers. No single barrier type appeared to be more formidable than any other. Our results indicate that healthy populations of darters may naturally be structured by drainage, but likely disperse across barriers enough to retain drainage-wide homogeneity.

Physical barrier type abuse-deterrent formulations: monitoring sintering-induced microstructural changes in polyethylene oxide placebo tablets by near infrared spectroscopy (NIRS)

Objective: The monitoring and evaluation of sintering-induced tablet strength of a polyethylene oxide (PEO) based placebo tables was accomplished using infrared spectroscopy (NIRS).Significance: Evaluation of high molecular weight PEO-based tablet matrices for abuse deterrent formulation applications is an analytical challenge. NIRS is one tool that can provide physical and chemical evaluation of this polymer and tablet system. In addition, the use of NIRS as a process analytical tool (PAT) to monitor oven sintering of pharmaceutical tablets has not been recorded in the literature. The multiplicative scattering correction (MSC) algorithm was also successfully applied as a new and fast way to calculate NIRS spectral slopes and intercepts to build models against tablet tensile strength with respect to sinter time.Methods: Both spectral slope regression (SSR) and spectral intercept regression (SIR) models were compared to commonly used partial least squares analysis (PLS) to evaluate placebo PEO based pharmaceutical tablets comprised of PEO at 70, 50, 30% w/w that were compressed at two solid fraction (SF) levels.Results: All three regression techniques, PLS, SSR, SIR, were evaluated for robustness and reliability and physical relevancy to the system studied. The methods were ranked in utility with SSR being the best method followed by SIR then PLS.Conclusions: The MSC algorithm was presented to quickly calculate spectral slopes and intercepts for use in SSR and SIR analysis. SSR models were successfully applied and assessed as the optimal modeling technique to monitor sintering of PEO-based matrix tablets.

The effect of hydrodynamic cavitation on performance of the alkaline aluminosilicate coatings for metal structures

Load-bearing metal structures working in atmospheric conditions are exposed to corrosion. Known-in-the art paint-and-lacquer protective coatings can provide protection of metal for rather short period of time (5…10 years). These structures can be effectively protected by more advanced coatings of new generation, namely: alkaline aluminosilicate binder-based coatings of barrier type. These binders differ from the known-in-the-art binding materials by formation in their hydration products of zeolite-like minerals and feldspathoids. The paper discusses principles laid down in formulating the binder composition in the (хК, уNa)2OAl2O3nSiO2mH2O system, target synthesis of hydration products of the binder matrix under influence of dynamic of the binder matrix in cavitation, optimal parameter order to synthesis of cavitation treatment aimed at nanostructuring of zeolite-like and hydromica phases after solidification. These coatings exhibit high corrosion resistance, high adhesion to metal substrate and durability results of restoration works that had been carried out in December 2010 of the Big Bell Tower of the Kiev Petchersk Lavra in order to protect corroded metal surfaces by applying the aluminosilicate binder-based coatings, the major constituent (binder) of which was represented by (0.72Na2O+0.28K2O)1.5Al2O3(4.56)SiO217.5H2O are discussed in details. In 2016, after 6 years of service in high humidity conditions and other aggressive exposures, the coated metal structures were examined and no sign of corrosion of metal substrate and damage of the applied coating was found.

Ultraviolet Detectors Based on Wide Bandgap Semiconductor Nanowire: A Review.

Ultraviolet (UV) detectors have attracted considerable attention in the past decade due to their extensive applications in the civil and military fields. Wide bandgap semiconductor-based UV detectors can detect UV light effectively, and nanowire structures can greatly improve the sensitivity of sensors with many quantum effects. This review summarizes recent developments in the classification and principles of UV detectors, i.e., photoconductive type, Schottky barrier type, metal-semiconductor-metal (MSM) type, p-n junction type and p-i-n junction type. The current state of the art in wide bandgap semiconductor materials suitable for producing nanowires for use in UV detectors, i.e., metallic oxide, III-nitride and SiC, during the last five years is also summarized. Finally, novel types of UV detectors such as hybrid nanostructure detectors, self-powered detectors and flexible detectors are introduced.

The impact of negative interest rates on optimal capital injections

In the present paper, we investigate the optimal capital injection behaviour of an insurance company if the interest rate is allowed to become negative. The surplus process of the considered insurance entity is assumed to follow a Brownian motion with drift. The changes in the interest rate are described via a Markov-switching process. It turns out that in times with a positive rate, it is optimal to inject capital only if the company becomes insolvent. However, if the rate is negative it might be optimal to hold a strictly positive reserve. We establish an algorithm for finding the value function and the optimal strategy, which is proved to be of barrier type. Using the iteration argument, we show that the value function solves the Hamilton–Jacobi–Bellman equation, corresponding to the problem.

CURRENT–VOLTAGE CHARACTERISTICS OF THERMALLY ANNEALED Ni/n-GaAs SCHOTTKY CONTACTS

The Schottky barrier type Ni/[Formula: see text]-GaAs contacts fabricated by us were thermally annealed at 600[Formula: see text]C and 700[Formula: see text]C for 1[Formula: see text]min. The apparent barrier height [Formula: see text] and ideality factor of the diodes were calculated from the forward bias current–voltage characteristic in 60–320[Formula: see text]K range. The [Formula: see text] values for the nonannealed and 600[Formula: see text]C and 700[Formula: see text]C annealed diodes were obtained as 0.80, 0.81 and 0.67[Formula: see text]eV at 300[Formula: see text]K, respectively. Thus, it has been concluded that the reduced barrier due to the thermal annealing at 700[Formula: see text]C promises some device applications. The current preferentially flows through the lowest barrier height (BH) with the temperature due to the BH inhomogeneities. Therefore, it was seen that the [Formula: see text] versus [Formula: see text] plots for the nonannealed and annealed diodes showed the linear behavior according to Gaussian distributions.

Dividends: From Refracting to Ratcheting

In this paper we consider an alternative dividend payment strategy in risk theory, where the dividend rate can never decrease. This addresses a concern that has often been raised in connection with the practical relevance of optimal classical dividend payment strategies of barrier and threshold type. We study the case where once during the lifetime of the risk process the dividend rate can be increased and derive corresponding formulae for the resulting expected discounted dividend payments until ruin. We first consider a general spectrally-negative Levy risk model, and then re fine the analysis for a diffusion approximation and a compound Poisson risk model. It is shown that for the diffusion approximation the optimal barrier for the ratcheting strategy is characterized by an unexpected relation to the case of refracted dividend payments. Finally, numerical illustrations for the diffusion case indicate that with such a simple ratcheting dividend strategy the expected value of discounted dividends can already get quite close to the respective value of the refracted dividend strategy, the latter being known to be optimal among all admissible dividend strategies.

A comparison of freeway median crash frequency, severity, and barrier strike outcomes by median barrier type

Median-crossover crashes are among the most hazardous events that can occur on freeways, often resulting in severe or fatal injuries. The primary countermeasure to reduce the occurrence of such crashes is the installation of a median barrier. When installation of a median barrier is warranted, transportation agencies are faced with the decision among various alternatives including concrete barriers, beam guardrail, or high-tension cable barriers. Each barrier type differs in terms of its deflection characteristics upon impact, the required installation and maintenance costs, and the roadway characteristics (e.g., median width) where installation would be feasible. This study involved an investigation of barrier performance through an in-depth analysis of crash frequency and severity data from freeway segments where high-tension cable, thrie-beam, and concrete median barriers were installed. A comprehensive manual review of crash reports was conducted to identify crashes in which a vehicle left the roadway and encroached into the median. This review also involved an examination of crash outcomes when a barrier strike occurred, which included vehicle containment, penetration, or re-direction onto the travel lanes. The manual review of crash reports provided critical supplementary information through narratives and diagrams not normally available through standard fields on police crash report forms. Statistical models were estimated to identify factors that affect the frequency, severity, and outcomes of median-related crashes, with particular emphases on differences between segments with varying median barrier types. Several roadway-, traffic-, and environmental-related characteristics were found to affect these metrics, with results varying across the different barrier types. The results of this study provide transportation agencies with important guidance as to the in-service performance of various types of median barrier.

Optimal dividends under Erlang(2) inter-dividend decision times

In the classical dividends problem, dividend decisions are allowed to be made at any time. Under such a framework, the optimal dividend strategies are often of barrier or threshold type, which can lead to very irregular dividend payments over time. In practice however companies distribute dividends on a periodic basis. In that spirit, “Erlangisation” techniques have been used to approximate problems with fixed inter-dividend decision times.When studying the optimality of such strategies, the existing literature focuses exclusively on the special case of exponential – that is, Erlang(1) – inter-dividend decision times. Higher dimensional models are surprisingly difficult to study due to the implicit nature of some of the equations. While some of this difficulty continues to exist in high dimensions, in this paper we provide a stepping stone to the general Erlang(n) problem by providing a detailed analysis of the optimality of periodic barrier strategies when inter-dividend-decision times are Erlang(2) distributed. Results are illustrated.

Introducing Meta-models for a More Efficient Hazard Mitigation Strategy with Rockfall Protection Barriers

The paper presents a new approach to assess the effecctiveness of rockfall protection barriers, accounting for the wide variety of impact conditions observed on natural sites. This approach makes use of meta-models, considering a widely used rockfall barrier type and was developed from on FE simulation results. Six input parameters relevant to the block impact conditions have been considered. Two meta-models were developed concerning the barrier capability either of stopping the block or in reducing its kinetic energy. The outcome of the parameters range on the meta-model accuracy has been also investigated. The results of the study reveal that the meta-models are effective in reproducing with accuracy the response of the barrier to any impact conditions, providing a formidable tool to support the design of these structures. Furthermore, allowing to accommodate the effects of the impact conditions on the prediction of the block–barrier interaction, the approach can be successfully used in combination with rockfall trajectory simulation tools to improve rockfall quantitative hazard assessment and optimise rockfall mitigation strategies.

Innovative Techniques/Technologies to Enhance the Durability of Civil Infra Structures PART 2: Corrosion Protection Techniques/ Technologies

Background: The durability of civil infrastructures is a severe problem faced by Scientists, Engineers and Technologies of 21st Century, due to the increasing pollution of our environments. This paper deals with innovative corrosion protection techniques/technologies to enhance the durability of civil infrastructures. Corrosion resistant rebars manufactured using Cu, P, Ni and Cr are capable of bearing the humid conditions of the coastal areas. TATA TISCON 500D rebars de-signed with diminished levels of impurities like S and P showed better corrosion resistance properties. Compared to CTD rebars, TMT rebars with tempered martensite zone showed improved corrosion re-sistance properties. Cement based coated steel rebars (inhibited cement slurry coated, cement polymer composite coated rebars) found to be more compatible for reinforcement corrosion control, in compari-son to galvinized and epoxy coated rebars. Fly ash, slag or silica fume, blended cements are finer as compared to OPC. The fineness reduced the permeability of blended cement concrete and improved the durability. Ternary blended cements, due to the fineness of the material and increased alumina, silica contents showed improved mechanical properties and better protection for steel in concrete. Owing to the unique molecular structure and high ion exchange capacity, chloride scavengers reduced the corro-sion susceptibility. Epoxy-polyurethane based surface coatings enhanced the durability as barrier type of coatings. Corrosion inhibiting admixtures such as calcium nitrite, citrate and stannate due to the for-mation of an insoluble film enhanced the corrosion resistance properties of reinforcements. Migrating corrosion inhibitors (MCI) based on amino alcohol, amines and nitrites showed superior corrosion resistance properties when compared to admixed inhibitor systems. Depending upon the environmental conditions, the implementation of corrosion protection technologies definitely enhanced the durability of civil infrastructures. Methods: The durability of the civil infrastructures such as National Highway Bridges, Nuclear Reactors, Elevated water tanks, On-shore and Off-shore concrete structures will be enhanced by adopting Innovative Corrosion protection Techniques/ Technologies such as i) Corrosion resistant rebars, ii)Coatings to steel rebars, iii) Blended cements, iv) Chloride scavengers for marine structures and v) Corrosion inhibiting admixtures for fresh structures. For existing structures, the following innovative technologies such as i). Coatings to concrete surface ii). Migrating corrosion inhibitors will be implemented. Results: After adopting the appropriate innovative corrosion protection techniques/technologies, the effect of treated structures will be monitored by conducting NDT techniques. Conclusion: Each and every innovative corrosion protection techniques/technologies have its own merits, demerits and limitations. Proper selection of method of corrosion protection strategies depending upon the environmental conditions can only lead to saving of money and enhancing the durability of civil infrastructures. In order to enhance the service life of civil infrastructures, it is essential to provide additional protective measures. Keywords: Protection strategies, corrosion resistant steel rebars, coatings to steel rebars, blended cements, admixtures, migrating corrosion inhibitors, chloride scavengers, repair/renovation strategy.

Selective Vulnerability to Transcellular Pathway of Blood-Brain Barrier in Chronic Stage of the Kainate Model of Temporal Lobe Epilepsy in Rats

1. Abstract 1.1. Background: The blood-brain barrier (BBB) integrity is severely affected in many epilepsy syndromes including temporal lobe epilepsy (TLE). 1.2. Aim: In the present study, we investigated the effects of acute and chronic seizures induced by kainic acid (KA) on the transport pathways of BBB in rats. 1.3. Methods: Electroencephalography (EEG) was recorded to evaluate seizure activity. Immunohistochemistry for claudin-5, a tight junction protein, caveolin-1, and the glial fibrillary acidic protein (GFAP), a marker of astrocyte activation, was performed. Electron microscopy was used to ultrastructurally assess the presence and route of extravasation of horseradish peroxidase (HRP), a permeability marker, in barrier type of brain capillary endothelial cells. 1.4. Results: The immunoreactivity of claudin-5 and caveolin-1 in hippocampus increased by both acute and chronic seizures (p 1.5. Conclusion: This study provides immunohistochemical and ultrastructural evidence of BBB disruption through a selective vulnerability of the transcellular transport via an increase in caveolar vesicles in the endothelial cells brain capillaries rather than activation of paracellular pathway in the KA-induced rat model of TLE. 2. Keywords: Blood-Brain Barrier; Caveolin-1; Claudin-5; Electron Microscopy; Kainic Acid; Temporal Lobe Epilepsy

Sensitivity Analysis of the Estimation of the Single-Number Sound Absorption Evaluation Index DLα

Abstract Acoustic barriers are assigned to the respective categories of sound absorbing properties on the basis of a single-number sound absorption evaluation index. Categories of absorbing properties play a significant role in selecting the barrier type for the given localisation. The estimation of the single-number sound absorption evaluation index is performed, among others, by means of measuring the sound absorption coefficient of the analysed acoustic barrier sample in the reverberation chamber. The sensitivity analysis of the determination of the single-number sound absorption evaluation index was performed in this work. The estimation of the input parameters uncertainty contribution to the expanded uncertainty of the sound absorption evaluation index, was done first. The Monte Carlo method and the reduction interval arithmetic were used for this aim. The relative sensitivity coefficients were determined by means of the author’s method based on the interval arithmetic. These coefficients contain information concerning the quantitative influence of the given input value on the final result.

Electric field tuned MoS2/metal interface for hydrogen evolution catalyst from first-principles investigations

Understanding the interfacial properties of catalyst/substrate is crucial for the design of high-performance catalyst for important chemical reactions. Recent years have witnessed a surge of research in utilizing MoS2 as a promising electro-catalyst for hydrogen production, and field effect has been employed to enhance the activity (Wang et al 2017 Adv. Mater. 29, 1604464; Yan et al 2017 Nano Lett. 17, 4109–15). However, the underlying atomic mechanism remains unclear. In this paper, by using the prototype MoS2/Au system as a probe, we investigate effects of external electric field on the interfacial electronic structures via density functional theory (DFT) based first-principles calculations. Our results reveal that although there is no covalent interaction between MoS2 overlayer and Au substrate, an applied electric field efficiently adjusts the charge transfer between MoS2 and Au, leading to tunable Schottky barrier type (n-type to p-type) and decrease of barrier height to facilitate charge injection. Furthermore, we predict that the adsorption energy of atomic hydrogen on MoS2/Au to be readily controlled by electric field to a broad range within a modest magnitude of field, which may benefit the performance enhancement of hydrogen evolution reaction. Our DFT results provide valuable insight into the experimental observations and pave the way for future understanding and control of catalysts in practice, such as those with vacancies, defects, edge states or synthesized nanostructures.

Effect of local elasticity of the matrix on magnetization loops of hybrid magnetic elastomers

To model magnetization loops of magnetorheological elastomers (MREs) with magnetically hard filler, we consider an assembly of single-domain particles possessing inversion-symmetrical shape and embedded in a soft polymer matrix. To describe the intrinsic behavior of the particle magnetic moments under an applied field, the Stoner-Wohlfarth approach is employed. Unlike the case of solid matrix, the particle in a MRE is able to rotate relative to its elastic environment, so that its equilibrium orientation results from the balance between the magnetic torque (exerted by the applied field at any magnetic moment that does not point along the field) and the elastic torque generated by the matrix. We assume that elastic resistance to the field-induced particle rotation could be presented as comprising of two contributions. The first one is valid for any not perfectly spherical particle and is independent of the particle–matrix adhesion. It reflects the fact that, when trying to rotate, the particle has to “shoulder its way” by deforming the adjoining regions of the matrix. In that case, for angular deviations up to 90° from the initial position, the resistance torque increases. However, as soon as the rotation angle grows up to the value but infinitesimally exceeding 90°, the elastic torque changes its sign and from now on forces the particle to rotate to 180°, where it attains the geometrical position that coincides with the initial one. Evidently, this process is of the barrier type: both orientations of the particle are equal in elastic energy. The second mechanism stems from the “memory” that a given particle has of its initial state and may be caused, for example, by some macromolecules grafted to its surface while curing the matrix of the MRE. This restoring force always tends to drag the particle to its 0° (initial) position. Therefore, the observed magnetization of a MRE sample comes out as a result of joint interplay of the Stoner-Wohlfarth and the two elastic mechanisms. In our simulations, we show that the proposed model in a natural way accounts for the two essential features observed (solely or together) in experiment, namely: (i) weak net coercivity of the MREs, whose filler particles as themselves are highly coercive, and (ii) asymmetric positions of the magnetization loops with respect to H=0 point at the (M-H) plane.